JP4413260B2 - High pressure fuel pump - Google Patents

Description

  The present invention relates to a high-pressure fuel pump that supplies fuel to an internal combustion engine.

  A high pressure fuel pump having a passage for returning the fuel in the pressure accumulating chamber to the pressurizing chamber of the high pressure fuel pump by bypassing the discharge valve when the high pressure fuel pump is stopped is known (for example, see Patent Document 1).

  In the high-pressure fuel pump disclosed in Patent Document 1, a passage is formed by a clearance between a functional component of the high-pressure fuel pump, such as a discharge valve, and a mounting hole provided in the housing for mounting the functional component, and the passage is formed through the passage. The fuel in the accumulator is returned to the pressurization chamber. As a result, when the high-pressure fuel pump is stopped, the high-pressure fuel in the accumulator is returned to the pressurizing chamber, the fuel pressure in the accumulator is lowered, and the fuel discharged during the pump operation is passed through the passage through the pressurizing chamber. It is suppressed that it returns to, and the fall of the volumetric efficiency of a pump is suppressed.

On the other hand, a passage that communicates the upstream side and the downstream side of the valve body is provided in the valve body of the discharge valve, and a valve body that allows only the flow of fuel from the downstream side to the upstream side is closed inside the passage, and the valve body is closed. A high-pressure fuel pump is known that includes a biasing means that biases the valve in the valve direction so that the fuel pressure downstream of the discharge valve after stopping the high-pressure fuel pump is maintained at a predetermined pressure (for example, Patent Documents). 2).
JP 2006-307829 A JP-A-4-86370

  However, in the high-pressure fuel pump disclosed in Patent Document 1, since the passage is formed by the clearance between the parts, the flow rate through the passage is limited, but the passage is always open. There is a problem that the fuel pressure in the pressure accumulating chamber is lowered to the fuel pressure in the pressurizing chamber, which is relatively low.

  Therefore, if the inventor employs the valve body and the urging means disclosed in Patent Document 2 in the passage disclosed in Patent Document 1, the fuel pressure in the pressure accumulating chamber is increased by the action of the valve body and the urging means. The inventor has arrived at the idea that a predetermined fuel pressure can be maintained without lowering the fuel pressure.

  However, simply providing the valve body and urging means disclosed in Patent Document 2 in the passage disclosed in Patent Document 1 causes a problem that the structure becomes complicated.

  The present invention has been made to solve the above-described problems, and its purpose is to allow the fuel in the pressure accumulation chamber to escape to the pressurization chamber and to maintain the fuel pressure in the pressure accumulation chamber at a predetermined pressure when the high-pressure fuel pump is stopped. On the other hand, an object of the present invention is to provide a high-pressure fuel pump that can realize a high-pressure fuel pump that suppresses a decrease in volumetric efficiency of the pump with a very simple structure when the high-pressure fuel pump is in operation.

According to a first aspect of the present invention, there is provided a high-pressure fuel pump that pressurizes fuel and pumps the fuel toward a pressure accumulating chamber, and includes a housing having a pressurizing chamber and a first passage that communicates the pressurizing chamber and the pressure accumulating chamber. A plunger that is reciprocally accommodated in the housing and pressurizes the fuel sucked into the pressurizing chamber, and is provided in the first passage and opens when the pressure in the pressurizing chamber exceeds a predetermined pressure. Is a second passage that connects the pressure accumulation chamber side and the pressure chamber side of the discharge valve, and a second passage having a valve seat in the middle of the passage, and pressurization from the pressure accumulation chamber side A valve body seated on the valve seat so as to allow only the flow of fuel to the chamber side, an urging means for urging the valve body in the seating direction, and provided in the second passage, are pressurized from the pressure accumulating chamber side. A throttle part that restricts the flow of fuel to the chamber side, and the throttle part includes a side wall of the valve body and an inner wall of the second passage Gap Der formed between is, the housing, one of which communicates with the first passage of the accumulator chamber side than the discharge valve and the other in communication with the first passage of the pressurizing chamber side of the discharge valve A relief passage is formed, and a relief valve is provided in the relief passage to open the pressure in the pressure accumulation chamber to the pressurization chamber when the pressure accumulation chamber is in an abnormally high pressure state. It is characterized by being formed inside the body .

  The high-pressure fuel pump has a second passage that communicates the pressure accumulation chamber side and the pressurization chamber side of the discharge valve in addition to the first passage provided with the discharge valve. For this reason, even if the first passage is closed by the discharge valve after the high-pressure fuel pump is stopped, the fuel pressure in the pressure accumulating chamber can be released to the pressurizing chamber through the second passage. .

  The second passage has a valve seat. In the second passage, a valve body seated on the valve seat so as to allow only the flow of fuel from the pressure accumulating chamber side to the pressurizing chamber side, and biasing means for biasing the valve body in the seating direction, Is housed. Thereby, when the fuel pressure on the pressure accumulating chamber side is lower than the urging force of the urging means, the flow of fuel to the pressurizing chamber side is stopped. For this reason, the fuel pressure in the pressure accumulating chamber can be kept higher than the fuel pressure in the pressurizing chamber. As a result, the fuel pressure in the pressure accumulating chamber can be increased as quickly as possible when the high-pressure fuel pump is restarted.

Furthermore, since the throttle part is formed in the middle of the second passage, the flow rate of the fuel passing through the second passage can be limited. For this reason, at the time of a high-pressure fuel pump operation | movement, the fall of the volume efficiency of a high-pressure fuel pump by discharge fuel returning to a pressurization chamber through a 2nd channel | path can be suppressed.
The throttle portion is a gap formed between the side wall of the valve body and the inner wall of the second passage. That is, the throttle portion is formed by only the second passage and the valve body necessary for holding the fuel pressure in the pressure accumulating chamber at or above the fuel pressure in the pressurizing chamber when the pump is stopped. The diaphragm part is formed without using individual parts for forming the diaphragm part. According to this, the throttle part can be easily formed only by assembling the valve body to the second passage. Further, it is not necessary to process the aperture part separately.

In addition, since the second passage that accommodates the valve body, the urging member, and the throttle portion is formed inside the valve body of the relief valve, the second passage is connected to the high-pressure fuel without complicating the structure of the housing. It can be provided in the pump. Further, the relief valve does not operate until an abnormally high pressure state is reached. That is, in a normal state, the relief valve is in a stationary state. Therefore, the operation of the valve body provided inside the relief valve can be stabilized.

  The invention according to claim 2 of the present invention is characterized in that the side wall of the valve body is a sliding portion that slides with the inner wall of the second passage so that the valve body is guided in the seating direction.

  A sliding portion that slides with the inner wall of the second passage is formed on the side wall of the valve body. Further, the sliding portion slides with the inner wall so as to guide the valve body in the direction in which the valve body is detached and seated. For this reason, the operation of the valve body is stabilized.

  According to a third aspect of the present invention, the valve body includes a valve body portion that is seated on the valve seat, and a cylindrical portion that extends from the valve body portion along the axial direction of the second passage. Is characterized in that the outer diameter is smaller than that of the valve body part and a sliding part is formed on the side wall.

  The cylinder portion has an outer diameter smaller than that of the valve body portion, and has a sliding portion that guides the valve body portion in the axial direction of the second passage on the side wall. If the length of the sliding portion, that is, the length of the cylindrical portion is increased, the operation of the valve body portion is further stabilized. Further, since the outer diameter of the cylinder part is smaller than the outer diameter of the valve body part, even if the length of the cylinder part is lengthened to stabilize the operation of the valve body part, the weight increase of the valve body can be minimized. it can. Accordingly, it is possible to improve the stability of the operation of the valve body while suppressing a decrease in the responsiveness of the valve body as much as possible.

  The invention according to claim 4 of the present invention is characterized in that the cylindrical portion is disposed closer to the pressure accumulating chamber than the valve seat.

  The cylinder part moves while sliding on the inner wall of the second passage together with the valve body part. Accordingly, when the valve body portion moves in the direction away from the seated state on the valve seat, the sliding length between the sliding portion of the cylindrical portion and the inner wall decreases compared to the seated state. On the other hand, when the valve body portion moves in the seating direction from the separated state, the sliding length increases compared to the separated state. As the sliding length changes, the sliding resistance also changes. The longer the sliding resistance, the harder the valve body moves.

  By disposing the cylinder portion closer to the pressure accumulating chamber than the valve seat, the valve body is difficult to open and closes easily. For this reason, when the fuel pressure in the pressurizing chamber becomes lower than that in the accumulator chamber during the operation of the high-pressure fuel pump, the amount of fuel that flows back to the pressurizing chamber via the throttle portion can be minimized.

The fuel pressurized in the high-pressure fuel pump for pumping toward the accumulation chamber, pressure chamber, and a housing having a first passage connecting the pressurizing chamber and the accumulation chamber, is reciprocally movably accommodated in the housing A plunger that pressurizes the fuel sucked into the pressurizing chamber, a discharge valve that is provided in the first passage, opens when the pressure in the pressurizing chamber exceeds a predetermined pressure, and supplies the fuel in the pressurizing chamber to the pressure accumulating chamber; A passage member forming a second passage communicating the pressure accumulation chamber side of the discharge valve and the pressure chamber or the low-pressure portion side upstream of the pressure chamber,
The second passage is provided with a partition member that divides the second passage into a pressure storage chamber side and a pressurization chamber side, and the partition member is cylindrical with a columnar core member and a material richer in elastic force than the core member. The elastic member is formed so as to cover the outer peripheral wall surface of the core member, and can obtain a predetermined surface pressure between the inner peripheral wall and the outer peripheral wall of the core member, and between the outer peripheral wall and the inner peripheral wall of the second passage. You may have.

  According to this configuration, the partition member that divides the second passage into the pressure accumulating chamber side and the pressurizing chamber side or the low-pressure part side is composed of the core member and the elastic member having a higher elastic force than the core member. The core member and the elastic member are combined so that a predetermined surface pressure is obtained between the inner peripheral wall of the elastic member and the outer peripheral wall of the core member, and between the outer peripheral wall of the elastic member and the inner peripheral wall of the second passage. ing.

  According to the partition member having such a structure, when the high pressure fuel pump is stopped and a large differential pressure is generated between the pressure accumulating chamber side and the pressurizing chamber side or the low pressure portion side, the high pressure fuel on the pressure accumulating chamber side becomes the core. It penetrates into a gap formed between the member and the elastic member or between the second passage and the elastic member.

  Since the elastic member is richer in elasticity than the core member and the second passage, if the high-pressure fuel that has entered the gap overcomes the surface pressure generated between the core member and the elastic member or between the second passage and the elastic member, the elastic member The member is deformed, the gap is expanded by the fuel pressure, and the fuel flows out to the pressurizing chamber side or the low pressure part side.

  Thereby, even if the discharge valve is closed after the high-pressure fuel pump is stopped, the high-pressure fuel on the pressure accumulation chamber side is released to the pressurizing chamber side or the low-pressure portion side that is the low-pressure side through the gap. be able to.

  Further, since one member forming the gap is an elastic member, the differential pressure becomes a predetermined value or less, and the surface pressure between the core member and the elastic member, or between the second passage and the elastic member is on the pressure accumulation chamber side. If the fuel pressure is exceeded, the gap is automatically closed. As a result, the fuel flow from the pressure accumulating chamber side to the pressurizing chamber side or the low pressure part side can be stopped, the fuel pressure on the pressure accumulating chamber side can be kept near a predetermined value, and the pressure accumulating chamber when the high pressure fuel pump is restarted The fuel pressure can be increased as quickly as possible.

Further, according to this configuration , it is possible to control the flow and stop of the fuel only by the core member and the elastic member that form a gap that communicates the pressure accumulating chamber side with the pressurizing chamber side or the low pressure portion side. That is, no additional means for stopping the outflow of fuel (the urging means for seating the valve element on the valve seat) is required. Therefore , since there is no need to provide such means separately, the structure of the partition member (pressure holding mechanism) that reduces the fuel pressure on the pressure accumulating chamber side after the high-pressure fuel pump stops to a predetermined value and maintains the pressure value is further improved. It can be simple.

  Further, according to this configuration, the gap communicating between the pressure accumulation chamber side and the pressurizing chamber side, or the pressure accumulation chamber side and the low pressure portion side is such that the opening and closing of the gap can be controlled by the fuel pressure that enters. Therefore, the size of the gap can be made minute compared to the case where the gap is formed by providing the rigid objects close to each other. According to this, the amount of fuel leakage flowing out to the pressurizing chamber side or the low pressure part side through this gap can be limited as much as possible, and when the high pressure fuel pump is operated, the discharged fuel passes through the second passage through the pressurizing chamber. Or the fall of the volumetric efficiency of the high-pressure fuel pump by returning to a low-pressure part can be suppressed.

Elastic member, the tubular member whose inner peripheral wall is supported by the outer peripheral wall of the core member, and provided on the outer peripheral side of the tubular member, the inner peripheral wall of the second passage with close contact with the outer peripheral wall of the tubular member You may be comprised from the rubber | gum O-ring which closely_contact | adheres .

  According to this configuration, the elastic member includes a cylindrical tubular member supported by the outer peripheral wall of the core member, and a rubber O-ring that is in close contact with the cylindrical outer peripheral wall and the inner peripheral wall of the second passage. Therefore, the gap formed by the differential pressure between the pressure accumulating chamber side and the pressurizing chamber side or the low-pressure part side is between the outer peripheral wall of the core member and the cylindrical member disposed on the inner peripheral side with respect to the second passage. Limited to the inner wall. For this reason, the circumferential length of the gap formed can be shortened. According to this, it is possible to limit the leakage amount of the fuel flowing out from the pressure accumulating chamber side to the pressurizing chamber side or the low pressure portion side as much as possible, and the fuel on the pressure accumulating chamber side is more than intended. It is possible to suppress the outflow.

  By the way, there are various types of vehicles on which a fuel system including a high-pressure fuel pump is mounted or specifications of an internal combustion engine. For this reason, the length (volume) of the fuel piping of the fuel system, the heat received by the fuel piping from the internal combustion engine, and the state of heat dissipation of the fuel piping also vary depending on the type of vehicle and the specifications of the internal combustion engine.

  For this reason, the amount of fuel leakage required for the pressure holding mechanism varies depending on the type of vehicle on which the high-pressure fuel pump is mounted and the specifications of the internal combustion engine. Further, the value of the fuel pressure (holding pressure) that should be maintained after the fuel pressure is reduced also varies depending on the type of vehicle and the specifications of the internal combustion engine.

The Gu image member, the resistance adjusting unit for adjusting the flow resistance of fuel flowing through the gap formed between the core member and the tubular member may be provided.

  According to this configuration, by adjusting the flow resistance of the fuel flowing through the gap, it is possible to control the progress of the fuel that has entered the gap between the core member and the cylindrical member, and the leakage of the fuel flowing out from the gap The amount can be adjusted. In addition, when the fuel pressure on the accumulator side becomes a holding pressure determined by the type of vehicle, the specifications of the internal combustion engine, etc., the leakage amount can be made zero and the pressure is maintained. You can also.

Resistance adjusting unit may we contact pressure adjustment portion der to adjust the surface pressure between the core member and the tubular member.

  According to this configuration, the size of the gap formed between the core member and the cylindrical member can be adjusted by adjusting the surface pressure between the core member and the cylindrical member. The flow resistance of the flowing fuel can be adjusted. The flow resistance can be adjusted only with the member forming the gap.

As a specific means for adjusting the surface pressure, a space is formed between the core member and the cylindrical member by forming a groove in the outer peripheral wall surface of the core member or the inner peripheral wall surface of the cylindrical member. The surface pressure is reduced. And the surface pressure which generate | occur | produces between both can be adjusted by adjusting the width | variety of the axial direction or the circumferential direction of the groove | channel.

In addition , by setting the inner diameter d of the inner peripheral wall of the cylindrical member in a state before the core member is inserted into the cylindrical member to be smaller than the outer diameter D of the core member, the core member is formed on the inner peripheral wall of the cylindrical member. When inserted, a predetermined surface pressure is generated between the core member and the cylindrical member. Moreover, the surface pressure which generate | occur | produces can be adjusted by adjusting the interference margin calculated | required as the difference of the outer diameter D and the internal diameter d.

Furthermore , the surface pressure generated between the core member and the tubular member can also be adjusted by adjusting the tightening force of the O-ring that fastens the tubular member.

In this case, when the O-ring is installed between the cylindrical member and the second passage, if the O-ring protrudes from both ends in the axial direction of the cylindrical member, the tight force of the O-ring is appropriately applied to the cylindrical member. Can't give. On the other hand , the axial length of the O-ring is a length that does not protrude from both ends in the axial direction of the tubular member when the O-ring is installed between the tubular member and the second passage. May be.

  According to this configuration, it is possible to appropriately apply the tightening force of the O-ring to the cylindrical member.

Further , the O- ring tightening force can be appropriately applied to the tubular member by providing the core member with a stopper portion that prevents the axial end portions of the O- ring from protruding from both axial end portions of the tubular member. it can.

Resistance adjusting unit may it axial length Sadea the tubular member.

  According to this configuration, the flow resistance of the fuel flowing through the gap formed between the core member and the tubular member can be adjusted by adjusting the axial length of the tubular member. The flow resistance of the fuel can be adjusted by a simple means of adjusting the axial length of the cylindrical member.

Radial cross-section of the core member and the tubular member may be I-circular der.

  According to this structure, since the radial direction cross section of the core member and the cylindrical member constituting the partition member is circular, manufacture and procurement of each component are facilitated, and an increase in manufacturing cost can be suppressed.

Elastic member, the inner wall is supported by the outer peripheral wall of the core member, the outer peripheral wall may be composed of only the cylindrical member supported on the inner peripheral wall of the second passage.

According to this configuration, elastic member is composed of only the cylindrical member. For this reason, the number of parts of the partition member can be reduced, and the structure can be simplified.

The Gu image member, clearance, and the tubular member and the resistance adjusting unit for adjusting the flow resistance of fuel flowing through the gap formed between the second passage formed between the core member and the tubular member It may be provided .

According to this configuration, by adjusting the flow resistance of the fuel flowing through the gap formed between the core member and the cylindrical member and the gap formed between the cylindrical member and the second passage, The amount of fuel leaking from the gap can be adjusted by controlling the progress of the fuel that has entered the gap. In addition, when the fuel pressure on the accumulator side becomes a holding pressure determined by the type of vehicle, the specifications of the internal combustion engine, etc., the leakage amount can be made zero and the pressure is maintained. You can also.

Resistance adjusting unit may we contact pressure adjustment portion der to adjust the surface pressure between the surface pressure, and the tubular member and the second passage between the core member and the tubular member.

  According to this configuration, the size of both the gaps can be adjusted by adjusting the surface pressure between the core member and the cylindrical member and the surface pressure between the cylindrical member and the second passage. The flow resistance of the fuel flowing through both gaps can be adjusted. Since the flow resistance can be adjusted only by the member that forms the gap, the structure of the partition member can be simplified.

Specifically, as a means for adjusting the surface pressure, the inner diameter d1 of the inner peripheral wall of the cylindrical member is smaller than the outer diameter D1 of the core member in a state before the core member and the cylindrical member are assembled to the second passage. By setting the outer diameter d2 of the wall to be larger than the passage diameter D2 of the second passage, the core member is inserted into the tubular member, and when inserted into the second passage, the core member and the tubular member, A predetermined surface pressure is generated between the second passage and the cylindrical member. Further, the generated surface pressure can be adjusted by adjusting the inner peripheral side interference allowance and the outer peripheral side interference allowance obtained as the difference between the inner diameter d1 and the outer diameter D1, and the outer diameter d2 and the passage diameter D2.

When the elastic member composed only of the tubular member, the resistance adjusting unit may it axial length Sadea the tubular member.

  According to this configuration, by adjusting the axial length of the cylindrical member, the fuel flowing through the gap formed between the core member and the cylindrical member and between the cylindrical member and the second passage is arranged. Distribution resistance can be adjusted. The flow resistance of the fuel can be adjusted by a simple means of adjusting the axial length of the cylindrical member.

When the elastic member composed only of the tubular member, the radial cross section of the core member and the tubular member may be I-circular der.

  According to this structure, since the radial direction cross section of the core member and the cylindrical member constituting the partition member is circular, manufacture and procurement of each component are facilitated, and an increase in manufacturing cost can be suppressed.

The passing path member is said housing, one end of the second passage may be connected to the pressurizing chamber.

  According to this configuration, during the plunger intake stroke, the pressurizing chamber is in a lower pressure than the accumulator side, and the high-pressure fuel on the accumulator chamber flows out from the accumulator chamber side via the partition member of the second passage. Even so, the spilled fuel is returned to the pressurizing chamber. For this reason, the fall of the volumetric efficiency of a high-pressure fuel pump can be suppressed as much as possible.

The passing path member is said housing, one end of the second passage may be connected to the low pressure section.

  According to this structure, compared with the case where one edge part of a 2nd channel | path is connected to a pressurization chamber, the freedom degree of installation of a 2nd channel | path can be raised, and the raise of manufacturing cost can be suppressed.

Passing path member may me discharge valve der.

  According to this configuration, even when the second passage cannot be formed in the housing, the partition member can be provided in the high-pressure fuel pump.

The housings are connected to the first passage of the accumulator chamber side than the one end the discharge valve, it is a relief passageway other end is connected to the low pressure portion of the upstream side of the pressurizing chamber or the pressurizing chamber is formed, the relief passage relief valve is provided in which the fuel pressure in the accumulator chamber side is opened When an abnormal high pressure, the passage member may me relief valve der.

  According to this configuration, the partition member is formed on the relief valve. For this reason, it can suppress that the structure of a housing becomes complicated.

  Hereinafter, a plurality of embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
A fuel supply system using a high-pressure fuel pump according to a first embodiment of the present invention is shown in FIG. The fuel supply system according to the present embodiment is a so-called direct injection gasoline supply system that directly injects fuel into a cylinder of an internal combustion engine (for example, a gasoline engine).

  The fuel supply system 1 includes a low pressure fuel pump 2, a high pressure fuel pump 3, a delivery pipe 4, a fuel injection valve 5, and the like.

  The low-pressure fuel pump 2 is an electric pump that pumps up fuel in the fuel tank 6 and supplies it to the high-pressure fuel pump 3. The high-pressure fuel pump 3 is a plunger pump including a plunger 11 and a pressurizing chamber 18, and pressurizes the fuel supplied from the low-pressure fuel pump 2 in the pressurizing chamber 18 and supplies it to the delivery pipe 4. The high-pressure fuel pump 3 includes a discharge valve 20 that opens when the pressure of the fuel pressurized in the pressurizing chamber 18 exceeds a predetermined pressure and supplies high-pressure fuel to the delivery pipe 4. The delivery pipe 4 corresponds to the pressure accumulating chamber described in the claims.

  The high-pressure fuel pump 3 includes a relief valve 30 that returns the downstream fuel to the pressurizing chamber side when the pressure on the downstream side of the high-pressure fuel pump 3 exceeds the abnormal pressure. The relief valve 30 is accommodated in the housing of the high pressure fuel pump 3.

  The delivery pipe 4 accumulates fuel whose pressure has been increased by the high-pressure fuel pump 3. The delivery pipe 4 is connected with a fuel injection valve 5 provided for each cylinder of the internal combustion engine 7. The fuel injection valve 5 injects high-pressure fuel supplied from the delivery pipe 4 into a combustion chamber formed in each cylinder.

  Next, the configuration of the high-pressure fuel pump 3 will be described in detail with reference to FIGS. The high pressure fuel pump 3 includes a cylinder 80, a housing cover 90, a plunger 11, a metering valve 60, a discharge valve 20, a relief valve 30, and the like.

  The cylinder 80 and the housing cover 90 constitute a housing described in the claims. The cylinder 80 is made of stainless steel or the like. The cylinder 80 supports the plunger 11 so as to be able to reciprocate. The sliding portion 81 of the cylinder 80 is formed by being hardened by induction hardening or the like.

  2 and 3, the cylinder 80 is provided with a pipe joint and a metering valve 60 (not shown) connected to the low pressure fuel pump 2 on the fuel inlet side, and the discharge valve 20 and the relief on the fuel outlet side. A valve 30 is attached.

  In the cylinder 80, a suction passage 82, a pressurizing chamber 18, a discharge passage 83, a return passage 85, a relief passage 86, and the like are formed. A suction chamber 91 is formed above the cylinder 80 between the upper end portion of the cylinder 80 and the housing cover 90. An outlet portion 84 is formed on the fuel outlet side of the discharge passage 83.

  The suction passage 82 is a passage connecting the suction chamber 91 and the pressurization chamber 18. The discharge passage 83 is a passage connecting the pressurizing chamber 18 and the outlet portion 84. The discharge passage 83 corresponds to the first passage described in the claims. The return passage 85 is a passage connecting the pressurizing chamber 18 and the discharge passage 83. The escape passage 86 is a passage connecting the sliding portion 81 and the suction chamber 91.

  The plunger 11 is supported by the sliding portion 81 of the cylinder 80 so as to be able to reciprocate. The pressurizing chamber 18 is formed on one end side in the reciprocating direction of the plunger 11. A head 12 formed on the other end side of the plunger 11 is coupled to a spring seat 13. A spring 15 is provided between the spring seat 13 and the cylinder 80.

  The spring seat 13 is pressed against the bottom inner wall of the tappet 14 (see FIG. 1) by the urging force of the spring 15. When the bottom outer wall of the tappet 14 slides with the cam 16 by the rotation of the cam 16 (see FIG. 1), the plunger 11 reciprocates.

  An oil seal 17 is provided at the end of the sliding portion 81 opposite to the pressurizing chamber 18. The oil seal 17 prevents oil from entering the pressurizing chamber 18 from the internal combustion engine 7 and prevents fuel leakage from the pressurizing chamber 18 into the internal combustion engine 7. The fuel leaked from the sliding portion of the plunger 11 and the cylinder 80 to the oil seal 17 side is returned from the escape passage 86 to the suction chamber 91 on the low pressure side. Thereby, it can suppress that a high fuel pressure is added to the oil seal 17.

  As shown in FIG. 2, the metering valve 60 includes a valve seat member 61, a valve member 63, a valve closing spring 64, a spring seat 65, an electromagnetic drive unit 66, and the like. The metering valve 60 is a valve that controls the amount of fuel sucked into the pressurizing chamber 18 from the suction chamber 91. The valve seat member 61, the valve member 63, the valve closing spring 64 and the spring seat 65 are accommodated in an accommodation hole 87 formed in the cylinder 80. The accommodation hole 87 is formed in the middle of the suction passage 82. The bottom of the accommodation hole 87 is connected to the suction passage 82 on the pressurizing chamber 18 side, and the side wall of the accommodation hole 87 is connected to the suction passage 82 on the suction chamber 91 side.

  The valve seat member 61 is formed in a cylindrical shape and is supported on the side wall of the accommodation hole 87. The valve seat member 61 has a valve seat 62 on the inner peripheral wall on which the valve member 63 is seated. The valve member 63 is formed in a bottomed cylindrical shape, and is accommodated in the valve seat member 61 so that the bottom outer wall is seated on the valve seat 62. A valve closing spring 64 is accommodated on the inner peripheral wall side of the valve member 63.

  One end of the valve closing spring 64 is supported by a spring seat 65 attached to the valve seat member 61, and the other end is supported by the bottom inner wall of the valve member 63. The valve member 63 is pressed in the direction of seating on the valve seat 62 by the urging force of the valve closing spring 64. When the valve member 63 is seated on the valve seat 62, the communication between the suction chamber 91 and the pressurizing chamber 18 is blocked.

  The electromagnetic drive unit 66 includes a body 67, a fixed core 68, a movable core 70, a pin 71, a valve opening spring 72, a coil 73, a connector 74, and the like.

  The body 67 covers the opening of the accommodation hole 87 and supports a fixed core 68 made of a magnetic material. The fixed core 68 has a suction part 69.

  The movable core 70 is made of a magnetic material, and is provided on the fixed core 68 on the suction portion 69 side. The movable core 70 is coupled to a pin 71 provided so as to penetrate the body 67. The attracting unit 69 generates a magnetic attraction force that attracts the movable core 70 between the movable core 70. The pin 71 reciprocates together with the movable core 70 to move the valve member 63 in the seating direction.

  A valve-opening spring 72 is provided between the fixed core 68 and the movable core 70. The biasing force of the valve opening spring 72 is larger than the biasing force of the valve closing spring 64. For this reason, the movable core 70 moves away from the fixed core 68 when no magnetic attractive force is generated in the attracting portion 69. That is, the valve member 63 is moved in a direction away from the valve seat 62. As a result, the suction chamber 91 and the pressurizing chamber 18 communicate with each other.

  The coil 73 is provided on the outer peripheral side of the fixed core 68. A connector 74 that supplies electric power to the coil 73 is provided on the outer peripheral side of the coil 73. When electric power is supplied to the coil 73 from the outside, a magnetic flux passing through the fixed core 68 and the movable core 70 is generated, and a magnetic attraction force acts between the attraction unit 69 and the movable core 70. Due to the generation of the magnetic attractive force, the movable core 70 moves to the fixed core 68 side, and the valve seat 62 is seated on the valve member 63. As a result, the communication between the suction chamber 91 and the pressurizing chamber 18 is blocked.

  As shown in FIGS. 2 and 3, the discharge valve 20 includes a valve seat 21, a valve body 22, a stopper 27, and a spring 28, and is accommodated in the discharge passage 83. The valve seat 21 is formed on the inner wall of the discharge passage 83. The valve body 22 is formed in a substantially cylindrical shape, and is provided closer to the outlet portion 84 than the valve seat 21. The valve body 22 has a large diameter portion 23 and a small diameter portion 24. The large diameter portion 23 is slidably supported in the discharge passage 83. The small-diameter portion 24 is provided closer to the pressurizing chamber 18 than the large-diameter portion 23, and the tip of the small-diameter portion 24 is seated on the valve seat 21 when the valve body 22 moves to the pressurizing chamber 18 side.

  A plurality of through holes 26 communicating with a fuel passage 25 formed inside the valve body 22 are formed in the side wall of the small diameter portion 24. Thereby, when the valve body 22 is separated from the valve seat 21, the fuel that flows into the gap between the small diameter portion 24 and the discharge passage 83 passes through the through hole 26 and flows into the fuel passage 25, and the outlet portion. It flows toward 84.

  The stopper 27 is formed in a substantially cylindrical shape, and is provided closer to the outlet portion 84 than the valve body 22. The stopper 27 is fixed to the discharge passage 83 and restricts the movement of the valve body 22 toward the outlet portion 84. The spring 28 is provided between the stopper 27 and the large diameter portion 23 of the valve body 22. The spring 28 biases the stopper 27 and the valve body 22 so as to separate them. Thereby, the small diameter portion 24 of the valve body 22 is seated on the valve seat 21, and communication between the pressurizing chamber 18 and the outlet portion 84 is blocked.

  When a differential pressure is generated between the pressure chamber 18 side and the outlet portion 84 side of the valve body 22 and the force acting on the tip of the small diameter portion 24 of the valve body 22 exceeds the urging force of the spring 28, the valve body 22 The valve chamber 21 is separated from the valve seat 21 and the pressurizing chamber 18 and the outlet portion 84 communicate with each other.

  Here, the stopper 27 is fixed to the discharge passage 83 by press fitting or the like. By adjusting the position of the stopper 27 in the discharge passage 83, the moving amount of the valve element 22 and the set load of the spring 28 can be adjusted.

  As shown in FIG. 3, the relief valve 30 has a valve seat 31, a valve body 32, a stopper 35, a spring 36, and a pressure holding mechanism 40, and is accommodated in an accommodation hole 88 formed in the middle of the return passage 85. Yes. The return passage 85 is a passage connecting the discharge passage 83 and the pressurizing chamber 18, and one end thereof communicates with a gap formed between the small diameter portion 24 of the valve body 22 of the discharge valve 20 and the discharge passage 83. The other end is open to the pressurizing chamber 18. The bottom of the accommodation hole 88 is connected to the return passage 85 on the discharge valve 20 side, and the side wall of the accommodation hole 88 is connected to the return passage 85 on the pressurizing chamber 18 side.

  A valve seat 31 is formed at the periphery of the opening of the return passage 85 formed at the bottom of the accommodation hole 88. The valve body 32 is formed in a substantially cylindrical shape and is accommodated in the accommodation hole 88. The valve body 32 has a large diameter portion 33 and a small diameter portion 34. The large diameter portion 33 is slidably supported in the accommodation hole 88. The small diameter portion 34 is provided closer to the discharge valve 20 than the large diameter portion 33, and the tip of the small diameter portion 34 is seated on the valve seat 31 as the valve body 32 moves to the discharge valve 20 side.

  The stopper 35 is formed in a substantially cylindrical shape, and is provided closer to the opening of the accommodation hole 88 than the valve body 32. The stopper 35 is fixed to the accommodation hole 88 and closes the opening of the accommodation hole 88. The stopper 35 restricts the valve body 32 from moving toward the opening and prevents the valve body 32 from coming out of the accommodation hole 88.

  The spring 36 is provided between the stopper 35 and the large diameter portion 33 of the valve body 32. The spring 36 biases the stopper 35 and the valve body 32 so as to separate them. As a result, the small diameter portion 34 of the valve body 32 is seated on the valve seat 31 and the communication between the discharge passage 83 and the pressurizing chamber 18 is blocked. The urging force of the spring 36 is such that the valve can be maintained closed until the pressure in the discharge passage 83 on the outlet 84 side of the valve body 32, that is, the pressure in the delivery pipe 4 exceeds the abnormal pressure. Yes.

  When the fuel pressure in the delivery pipe 4 exceeds the abnormal pressure and the force acting on the tip of the small diameter portion 34 of the valve body 32 exceeds the urging force of the spring 36, the valve body 32 moves to the opening side of the accommodation hole 88. Then, it is separated from the valve seat 31. As a result, the discharge passage 83 and the pressurizing chamber 18 communicate with each other, and the high-pressure fuel in the delivery pipe 4 returns to the pressurizing chamber 18.

  Next, the structure of the valve body 32 of the relief valve 30 will be described in more detail with reference to FIG. The valve body 32 has a pressure holding mechanism 40 inside. The pressure holding mechanism 40 includes a fuel passage 41, a valve needle 47, a spring 51, and a stopper 52. The fuel passage 41 is formed through the large diameter portion 33 and the small diameter portion 34 of the valve body 32. The fuel passage 41 includes a large diameter passage 42 and a small diameter passage 43.

  The small diameter passage 43 is provided closer to the small diameter portion 34 than the large diameter passage 42. A valve seat 44 on which the valve needle 47 is seated is formed between the small diameter passage 43 and the large diameter passage 42. The small diameter portion 34 is formed with a through hole 45 that communicates the side wall of the small diameter portion 34 and the inner wall of the large diameter passage 42.

  The fuel passage 41 communicates with the outlet portion 84 side of the discharge passage 83, that is, the delivery pipe 4 side with respect to the discharge valve 20 via the return passage 85 on the discharge passage 83 side. The fuel passage 41 communicates with the pressurizing chamber 18, that is, with respect to the pressurizing chamber 18 rather than the discharge valve 20 through the through hole 45 and the return passage 85 on the pressurizing chamber 18 side. The fuel passage 41 and the return passage 85 described above form the second passage described in the claims.

  The valve needle 47 has a valve body portion 48 and a cylindrical portion 49. The valve body 48 is formed so that the outer diameter is larger than the inner diameter of the small diameter passage 43 and smaller than the inner diameter of the large diameter passage 42, and is accommodated in the large diameter passage 42. The valve body portion 48 can be detached from and seated on the valve seat 44. When the valve body portion 48 is seated on the valve seat 44, the communication between the delivery pipe 4 side of the discharge valve 20 and the pressurizing chamber 18 side is cut off. The The valve needle 47 corresponds to the valve body described in the claims.

  The cylindrical portion 49 is formed in a substantially cylindrical shape, and is provided so as to extend along the axial direction of the small diameter passage 43 from the end of the valve body portion 48 on the small diameter passage 43 side. The cylindrical portion 49 has a sliding portion 50 that slides in the small diameter passage 43 on its side wall, and is slidably supported on the inner wall 46 of the small diameter passage 43. The sliding portion 50 formed in the cylindrical portion 49 corresponds to the side wall described in the claims, and the inner wall 46 of the small diameter passage 43 corresponds to the inner wall of the second passage described in the claims.

  A sliding gap S <b> 1 is formed between the sliding portion 50 and the inner wall 46. Since the sliding gap S1 is formed, the amount of fuel flowing from the small diameter passage 43 to the large diameter passage 42 can be limited. The sliding gap S1 corresponds to the throttle part described in the claims.

  By moving the cylindrical portion 49 in the small-diameter passage 43, the valve body portion 48 can be stably operated in the seating direction. Thereby, the valve body 48 can be reliably detached from the valve seat 44. If the length in the axial direction of the tube portion 49 is increased, the operation of the valve body portion 48 can be further stabilized. Since the cylinder portion 49 has an outer diameter smaller than that of the valve body portion 48, it is possible to improve the stability of the operation of the valve body portion 48 while suppressing a decrease in responsiveness due to an increase in the weight of the valve needle 47 as much as possible.

  Further, the axial distance L of the sliding gap S1 is the longest when the valve body 48 is seated on the valve seat 44 as shown in FIG. The further away the valve body 48 is from the valve seat 44, the shorter the axial distance L is. That is, the shorter the axial distance L, the smaller the sliding resistance between the cylindrical portion 49 and the inner wall 46 of the small diameter passage 43. Specifically, the valve body portion 48 moves in the seating direction from the separated state, rather than when the valve body portion 48 starts moving in the seating direction from the seated state from the valve seat 44. Sometimes responsiveness is better. That is, the valve body 48 has a structure that is difficult to open and easy to close.

  A stopper 52 is provided on the opposite side of the valve body 48 from the tube portion 49. A spring 51 is provided between the valve body 48 and the stopper 52. The spring 51 urges the valve body 48 in a direction in which the valve body 48 is pressed against the valve seat 44. The spring 51 corresponds to the urging means described in the claims. When a differential pressure is generated between the discharge passage 83 side and the pressurizing chamber 18 side of the valve needle 47 and the force acting on the cylinder portion 49 exceeds the urging force of the spring 51, the valve body portion 48 is separated from the valve seat 44. The delivery valve 20 side of the discharge valve 20 and the pressurizing chamber 18 side are communicated.

  The urging force of the spring 51 is such that when the high-pressure fuel pump 3 is stopped, the fuel pressure of the delivery pipe 4 is lower than the fuel pressure when the internal combustion engine 7 is operating normally, and the low-pressure fuel pump 2 The valve needle 47 can be closed when a predetermined fuel pressure higher than the discharge pressure (feed pressure) is reached.

  Next, the operation of the high pressure fuel pump 3 will be described.

(1) Suction stroke When the plunger 11 descends, power is not supplied to the coil 73 of the metering valve 60. When the plunger 11 is lowered, the fuel pressure in the pressurizing chamber 18 is reduced, and the fuel in the suction chamber 91 is sucked into the pressurizing chamber 18 through the suction passage 82. The energization of the coil 73 of the metering valve 60 is in a state of being turned off until the plunger 11 reaches the bottom dead center.

(2) Return stroke Even if the plunger 11 rises from the bottom dead center toward the top dead center, the energization to the coil 73 is in an off state. For this reason, the fuel in the pressurizing chamber 18 is returned to the suction chamber 91 via the metering valve 60.

(3) Pressurization stroke When energization of the coil 73 is turned on during the return stroke, a magnetic attractive force is generated in the attracting portion 69 of the fixed core 68, and the movable core 70 and the pin 71 are attracted to the attracting portion 69. As a result, the valve member 63 is seated on the valve seat 62, the communication between the pressurizing chamber 18 and the suction chamber 91 is blocked, and the flow of fuel from the pressurizing chamber 18 to the suction chamber 91 is stopped.

  In this state, when the plunger 11 further rises toward the top dead center, the fuel in the pressurizing chamber 18 is pressurized and the fuel pressure rises. Then, the fuel pressure in the pressurizing chamber 18 increases. When the fuel pressure in the pressurizing chamber 18 becomes equal to or higher than a predetermined pressure, the valve element 22 is separated from the valve seat 21 against the biasing force of the spring 24, and the discharge valve 20 is opened. As a result, the fuel pressurized in the pressurizing chamber 18 is discharged from the outlet portion 84. The fuel discharged from the outlet portion 84 is supplied to the delivery pipe 4 shown in FIG.

  By repeating the steps (1) to (3), the high pressure fuel pump 3 pressurizes and discharges the sucked fuel. The amount of fuel discharged is metered by controlling the timing of energizing the coil 73 of the metering valve 60.

  At least in the strokes (1) and (2), the fuel pressure in the pressurizing chamber 18 is lower than the fuel pressure in the delivery pipe 4, so the valve body of the valve needle 47 accommodated in the relief valve 30. The part 48 is separated from the valve seat 44. Therefore, the fuel on the delivery pipe 4 side returns to the pressurizing chamber 18 side via the return passage 85 and the fuel passage 41 of the relief valve 30.

  However, in the fuel passage 41, a sliding gap S1 is formed between the sliding portion 50 formed on the side wall of the cylindrical portion 49 of the valve needle 47 and the inner wall 46 of the small-diameter passage 43. The flow of fuel from the 4 side is restricted. For this reason, it is possible to suppress a decrease in the volumetric efficiency of the high-pressure fuel pump 3 due to the fuel discharged from the pressurizing chamber 18 being returned to the pressurizing chamber 18 again.

  When the process proceeds to step (3), the fuel pressure in the pressurizing chamber 18 temporarily becomes higher than the fuel pressure in the delivery pipe 4, so that the valve body 48 of the valve needle 47 is seated on the valve seat 44. For this reason, the flow of the fuel in the delivery pipe 4 to the pressurizing chamber 18 is stopped.

  As described above, when the steps (1) to (3) are repeated, the valve needle 47 repeats the on-off valve. As described above, the valve needle 47 has a structure in which the tube portion 49 is slidably supported by the small-diameter passage 43 on the delivery pipe 4 side than the valve body portion 48, so that the valve needle 47 is difficult to open and close. ing. For this reason, the valve needle 47 is difficult to open when the process moves to the process (1) after the process (3), so that the fuel in the delivery pipe 4 is prevented from returning to the pressurizing chamber 18 as much as possible. be able to.

  Further, immediately after the high-pressure fuel pump 3 is stopped, the fuel pressure in the delivery pipe 4 is higher than that in the pressurizing chamber 18, so that the valve needle 47 is opened. For this reason, the fuel in the delivery pipe 4 returns to the pressurizing chamber 18 through the sliding gap S1, and the fuel pressure in the delivery pipe 4 decreases.

  Since the valve needle 47 is biased in the valve closing direction by the spring 51, the valve needle 47 is closed when the fuel pressure in the delivery pipe 4 is lowered to a predetermined pressure. As a result, the fuel pressure in the delivery pipe 4 can be maintained above the feed pressure. According to this configuration, when the high-pressure fuel pump 3 is started again, the fuel pressure in the delivery pipe 4 can be increased to the fuel pressure during normal operation in a short time.

  In the present embodiment, a throttle function for limiting the amount of fuel returning from the delivery pipe 4 side to the pressurizing chamber 18 side is formed by the sliding portion 50 of the cylindrical portion 49 of the valve needle 47 and the inner wall 46 of the small diameter passage 43. The sliding gap S1 is provided. The sliding gap S1 is formed of components necessary for maintaining the fuel pressure in the delivery pipe 4 at a predetermined pressure when the high-pressure fuel pump 3 is stopped. In other words, the aperture function is added without adding unnecessary components. According to this, the sliding gap S <b> 1 can be formed by a simple assembly in which the cylindrical portion 49 of the valve needle 47 is inserted into the small diameter passage 43. Further, it is not necessary to separately process a portion having the function of a diaphragm.

  In the present embodiment, since the valve needle 47 and the like are built in the relief valve 30 that does not operate during normal operation of the high-pressure fuel pump 3, the valve needle 47 can be operated stably.

(Second Embodiment)
A second embodiment of the present invention is shown in FIG. Components that are substantially the same as those of the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  In the second embodiment shown in FIG. 5, the pressure holding mechanism 40 built in the relief valve 30 in the first embodiment is built in the discharge valve 20.

  The pressure holding mechanism 140 built in the discharge valve 20 includes a fuel passage 141, a valve needle 147, a spring 151, and a stopper 152. The fuel passage 141 is formed through the large diameter portion 23 and the small diameter portion 24 of the valve body 22 of the discharge valve 20. The fuel passage 141 includes a large diameter passage 142 and a small diameter passage 143.

  The small diameter passage 143 is provided closer to the outlet portion 84 than the large diameter passage 142. A valve seat 144 on which the valve needle 147 is seated is formed between the large diameter passage 142 and the small diameter passage 143. The small diameter portion 24 is formed with a through hole 145 that communicates the side wall of the small diameter portion 24 and the inner wall 146 of the small diameter passage 143.

  The fuel passage 141 communicates with the outlet 84 side of the discharge passage 83, that is, with the delivery pipe 4 side than the discharge valve 20. The fuel passage 141 communicates with the pressurizing chamber 18, that is, with respect to the pressurizing chamber 18 rather than the discharge valve 20 through the through hole 145 and a gap between the small diameter portion 24 and the discharge passage 83. In this embodiment, the fuel passage 141 corresponds to the second passage described in the claims.

  The valve needle 147 has a valve body portion 148 and a cylindrical portion 149. The valve body portion 148 has an outer diameter larger than the inner diameter of the small diameter passage 143 and smaller than the inner diameter of the large diameter passage 142. When the valve body portion 148 is seated on the valve seat 144, the delivery pipe of the discharge valve 20 is formed. Communication between the 4 side and the pressurizing chamber 18 side is blocked.

  The cylindrical portion 149 is formed in a substantially cylindrical shape, and is provided so as to extend along the axial direction of the small diameter passage 143 from the end of the valve body portion 148 on the small diameter passage 143 side. The cylindrical portion 149 has a sliding portion 150 that slides on the inner wall 146 of the small diameter passage 143 on the side wall thereof. The cylindrical portion 149 is slidably supported on the inner wall 146.

  A sliding gap S <b> 2 is formed between the sliding portion 150 and the inner wall 146. Since the sliding gap S2 is formed, the amount of fuel flowing from the small diameter passage 143 to the large diameter passage 142 can be limited. The sliding gap S2 corresponds to the throttle portion described in the claims. If the axial length of the cylindrical portion 149 is increased, the amount of fuel passing through the sliding gap S2 can be further limited. Since the cylinder part 149 has an outer diameter smaller than that of the valve body part 148, even if the cylinder part 149 is extended in the axial direction, an increase in the weight of the valve needle 147 can be minimized.

  By moving the cylindrical part 149 in the small diameter passage 143, the valve body part 148 can be stably operated in the separation / seating direction. As a result, the valve body 148 can be reliably seated on and off from the valve seat 144.

  In addition, by configuring the pressure holding mechanism 140 in this way, the valve needle 147 is difficult to open and can be easily closed as with the pressure holding mechanism 40 of the first embodiment.

  A stopper 152 is provided on the opposite side of the valve body portion 148 from the cylinder portion 149. The stopper 152 is formed with a through hole 153 for allowing the fuel flowing into the large diameter passage 142 to flow into the discharge passage 83 on the pressurizing chamber 18 side. A spring 151 is provided between the valve body 148 and the stopper 152. The spring 151 urges the valve body portion 148 in a direction to press the valve seat 144 against the valve seat 144.

  As in the first embodiment, the urging force of the spring 151 is such that when the high-pressure fuel pump 3 is stopped, the fuel pressure of the delivery pipe 4 is lower than the fuel pressure when the internal combustion engine 7 is operating normally, and The valve needle 147 can be closed when a predetermined fuel pressure higher than the discharge pressure (feed pressure) of the low-pressure fuel pump 2 is reached.

  The pressure holding mechanism 140 configured as described above also has the same effect as the pressure holding mechanism 40 of the first embodiment. In the strokes (1) and (2), the fuel pressure in the pressurizing chamber 18 is lower than the fuel pressure in the delivery pipe 4, and therefore the discharge valve 20 is closed. In this state, the valve body 148 of the valve needle 147 is separated from the valve seat 144. For this reason, the fuel on the delivery pipe 4 side returns to the pressurizing chamber 18 side via the fuel passage 141.

  However, in the fuel passage 141, a sliding gap S2 is formed between the sliding portion 150 formed on the side wall of the cylindrical portion 149 of the valve needle 147 and the inner wall 146 of the small diameter passage 143. The flow of fuel from the 4 side is restricted. For this reason, a decrease in volumetric efficiency of the high-pressure fuel pump 3 can be suppressed.

  In the stroke (3), the fuel pressure in the pressurizing chamber 18 becomes higher than the fuel pressure in the delivery pipe 4, so that the discharge valve 20 is opened. In this state, the valve body 148 of the valve needle 147 is seated on the valve seat 144. For this reason, the flow of the fuel in the delivery pipe 4 to the pressurizing chamber 18 is stopped.

  As described above, also in the second embodiment, when the steps (1) to (3) are repeated, the valve needle 147 repeats the on-off valve. As described above, the valve needle 147 has a structure in which the cylindrical portion 149 is slidably supported by the small diameter passage 143 closer to the delivery pipe 4 than the valve body portion 148, so that the valve needle 147 is difficult to open and is easy to close. ing. For this reason, the valve needle 147 is difficult to open after the stroke of (3) to the stroke of (1), so that the fuel in the delivery pipe 4 is prevented from returning to the pressurizing chamber 18 as much as possible. be able to.

  Immediately after the high-pressure fuel pump 3 is stopped, the fuel pressure in the delivery pipe 4 is higher than that in the pressurizing chamber 18, so that the discharge valve 20 is closed and the valve needle 147 is opened. For this reason, the fuel in the delivery pipe 4 returns to the pressurizing chamber 18 through the sliding gap S2, and the fuel pressure in the delivery pipe 4 decreases.

  Since the valve needle 147 is biased in the valve closing direction by the spring 151, the valve needle 147 is closed when the fuel pressure in the delivery pipe 4 is lowered to a predetermined pressure. As a result, the fuel pressure in the delivery pipe 4 can be maintained above the feed pressure. According to this configuration, when the high-pressure fuel pump 3 is started again, the fuel pressure in the delivery pipe 4 can be increased to the fuel pressure during normal operation in a short time.

  A throttle function for limiting the amount of fuel returning from the delivery pipe 4 side to the pressurizing chamber 18 side is provided in a sliding gap S2 formed by the sliding portion 150 of the cylindrical portion 149 of the valve needle 147 and the inner wall 146 of the small diameter passage 143. I have it. Also according to this embodiment, the sliding gap S <b> 2 can be formed by a simple assembly in which the cylindrical portion 149 of the valve needle 147 is inserted into the small diameter passage 143, as in the first embodiment. Further, it is not necessary to separately process a portion having the function of a diaphragm.

  In addition, the type in which the pressure holding mechanism 140 is built in the discharge valve 20 as in this embodiment is particularly effective when the high-pressure fuel pump 3 is not provided with a relief valve.

  FIG. 6 shows a modification of the second embodiment. In this modification, the valve body 148 (see FIG. 5) of the valve needle 147a is a ball valve 148a. A cylindrical portion 149a is fixed to the end of the ball valve 148a on the small diameter passage 143 side by welding or the like. A sliding portion 150a that slides on the inner wall 146 of the small diameter passage 143 is formed on the side wall of the cylindrical portion 149a. A sliding gap S3 is formed between the sliding portion 150a and the inner wall 146. Other configurations are the same as those in FIG.

(Third embodiment)
A third embodiment of the present invention is shown in FIG. Components that are substantially the same as those of the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  In the third embodiment shown in FIG. 7, the pressure holding mechanism 240 is built in the accommodation hole 88 in which the relief valve 30 was accommodated in the first embodiment.

  The pressure holding mechanism 240 includes a valve seat 241, a valve needle 242, a spring 246 and a stopper 245. The valve seat 241 is formed at the periphery of the opening of the return passage 85 formed at the bottom of the accommodation hole 88. In this embodiment, the return passage 85 and the accommodation hole 88 correspond to the second passage described in the claims.

  The valve needle 242 is formed in a substantially cylindrical shape and has a valve body portion 243 and a cylindrical portion 244. The valve body portion 243 is accommodated in the accommodation hole 88, and the bottom side of the accommodation hole 88 is separated from the valve seat 241. The cylinder portion 244 is accommodated in the return passage 85 on the bottom side of the accommodation hole 88. A sliding portion 247 that slides with the inner wall 89 of the return passage 85 is formed on the side wall of the cylindrical portion 244. A sliding gap S4 is formed between the sliding portion 247 of the cylindrical portion 244 and the inner wall 89 of the return passage 85. The sliding gap S4 limits the amount of fuel that returns from the delivery pipe 4 side to the pressurizing chamber 18 side.

  The stopper 245 is formed in a substantially cylindrical shape, and is provided on the opening side of the accommodation hole 88 of the valve body portion 243. The stopper 245 is fixed to the accommodation hole 88 and closes the opening of the accommodation hole 88. The stopper 245 restricts the movement of the valve needle 242 toward the opening and prevents the valve needle 242 from coming out of the accommodation hole 88.

  The spring 246 is provided between the stopper 245 and the valve body portion 243. The spring 246 biases the valve body part 243 in a direction in which the valve body part 243 is pressed against the valve seat 241. As in the first embodiment, the urging force of the spring 246 is such that when the high-pressure fuel pump 3 is stopped, the fuel pressure of the delivery pipe 4 is lower than when the internal combustion engine 7 is operating normally, and the low-pressure fuel The valve needle 242 can be closed when a predetermined fuel pressure higher than the discharge pressure (feed pressure) of the pump 2 is reached.

  Since the operation of the valve needle 242 is the same as the operation of the valve needle 47 of the first embodiment, description thereof is omitted. Also according to this embodiment, the sliding gap can be formed by a simple assembly in which the cylindrical portion 244 of the valve needle 242 is inserted into the return passage 85 as in the first embodiment. Further, it is not necessary to separately process a portion having the function of a diaphragm.

  According to this embodiment, the pressure holding mechanism 240 is provided in the high-pressure fuel pump 3 using the accommodation hole 88 of the relief valve 30. For this reason, even when the relief valve 30 is provided outside the high-pressure fuel pump 3, the cylinder 80 having the accommodation hole 88 for accommodating the relief valve 30 can be used. For this reason, when the relief valve 30 is provided outside, there is no need to make a separate cylinder 80 in other cases. That is, the cylinder 80 can be shared.

(Fourth embodiment)
A fourth embodiment of the present invention is shown in FIGS. FIG. 8 shows a partial cross-sectional view of the high-pressure fuel pump 3 according to the fourth embodiment. 8 is a partial cross-sectional view corresponding to the line III-III in FIG. FIG. 9 shows a cross-sectional view of the pressure holding mechanism 340 built in the high-pressure fuel pump 3. FIG. 10 shows an exploded view of the pressure holding mechanism 340.

  The high pressure fuel pump 3 shown in FIG. 8 is provided with a pressure holding mechanism 340 as a partition member according to claim instead of the relief valve 30 accommodated in the accommodation hole 88 of the high pressure fuel pump 3 according to the first embodiment. It is a thing. In addition, in the high-pressure fuel pump 3 according to the fourth embodiment described below, the same reference numerals are given to substantially the same components as those in the first embodiment, and description thereof will be omitted.

  The pressure holding mechanism 340 includes a plug 341, a cylindrical member 349, an O-ring 352, a washer 353, and a clasp 354 and is accommodated in the accommodation hole 88. The pressure holding mechanism 340 is accommodated so as to partition the accommodation hole 88 into the delivery pipe 4 side and the pressurizing chamber 18 side. In this embodiment, the accommodation hole 88 and the return passage 85 correspond to the second passage described in the claims.

  As shown in FIGS. 8 and 9, the plug 341 is formed in a substantially cylindrical shape from a metal material. A constricted portion 342 is formed in the central portion, and a core portion 343 as a core member described in the claims is integrally formed at an end portion on the discharge passage 83 side. A male screw portion 346 is formed on the opening portion side of the receiving hole 88 to be engaged with a female screw portion 89 a formed on the inner peripheral wall of the opening end of the receiving hole 88. The return passage 85 on the pressurizing chamber 18 side communicates with a space formed by the constricted portion 342 in a state where the plug 341 is accommodated in the accommodation hole 88.

  A large-diameter portion 347 is formed between the core portion 343 and the constricted portion 342 of the plug 341. A concave groove 348 for fixing a stopper 354 for preventing a washer 353 attached to the core part 343 from coming off is formed at the tip of the core part 343.

  As shown in FIG. 9, an annular groove 345 is formed in the outer peripheral wall 344 of the core portion 343. A cylindrical member 349 is provided on the outer peripheral side of the core portion 343. The cylindrical member 349 is formed from a resin material that is more elastic than the core portion 343. In the present embodiment, the cylindrical member 349 is formed of, for example, Teflon (registered trademark). Teflon (registered trademark) is a material rich in fuel resistance, and is a material with little dimensional change due to fuel swelling. The resin material forming the cylindrical member 349 may be a material other than Teflon (registered trademark) as long as it is more elastic than the core portion 343 and less dimensional change due to fuel swelling.

  As shown in FIG. 9, a rubber O-ring 352 is provided outside the outer peripheral wall 350 of the cylindrical member 349. The O-ring 352 is in close contact with the outer peripheral wall 350 of the cylindrical member 349 on the inner peripheral side, and is in close contact with the inner peripheral wall 89 of the accommodation hole 88 on the outer peripheral side. Thereby, the space between the outer peripheral wall 350 of the cylindrical member 349 and the inner peripheral wall 89 of the accommodation hole 88 is sealed by the O-ring 352. In this embodiment, the core portion 343 corresponds to the core member recited in the claims, and the tubular member 349 and the O-ring 352 correspond to the elastic member recited in the claims.

  A washer 353 is provided at the tip of the core part 343. As shown in FIG. 9, the washer 353 is provided in the vicinity of the cylindrical member 349 and the O-ring 352, and the end of the O-ring 352 on the discharge passage 83 side protrudes from the axial end of the cylindrical member 349. It suppresses that. The large-diameter portion 347 of the plug 341 is provided in the vicinity of the cylindrical member 349 and the O-ring 352, and the end on the opening end side of the accommodation hole 88 of the O-ring 352 is the axial end of the cylindrical member 349. Suppresses overhanging. On the discharge passage 83 side of the washer 353, a stopper plate 354 formed in a substantially C shape that prevents the washer 353 from coming off is provided.

  Next, the assembly of the pressure holding mechanism 340 and the force acting between the parts constituting the pressure holding mechanism 340 will be described.

  As shown in FIG. 10, the pressure holding mechanism 340 is formed by assembling a cylindrical member 349, an O-ring 352, a washer 353, and a stopper 354 in order from the distal end side of the core portion 343 in the plug 341.

  As shown in FIG. 10, when the inner diameter of the inner peripheral wall 351 of the cylindrical member 349 is d and the outer diameter of the core portion 343 is D before the cylindrical member 349 is inserted into the core portion 343, the inner diameter d Is set smaller than the outer diameter D. For this reason, when the core part 343 is inserted into the inner peripheral wall 351 of the cylindrical member 349, the inner peripheral wall 351 of the cylindrical member 349 is pushed out by the outer peripheral wall 344 of the core part 343. As a result, a surface pressure corresponding to the difference between the outer diameter D and the inner diameter d is generated between the inner peripheral wall 351 of the cylindrical member 349 and the outer peripheral wall 344 of the core portion 343. Hereinafter, the difference between the outer diameter D and the inner diameter d is referred to as a fastening allowance.

  As shown in FIG. 10, the cross section of the O-ring 352 before being inserted into the accommodation hole 88 is circular. When the O-ring 352 is attached to the cylindrical member 349 and then inserted into the receiving hole 88, the O-ring 352 is sandwiched between the inner peripheral wall 351 of the cylindrical member 349 and the inner peripheral wall 89 of the receiving hole 88 and the cross section is deformed. To do. As a result, a repulsive force is generated in the O-ring 352, the surface of the O-ring 352 is brought into close contact with the outer peripheral wall 350 of the cylindrical member 349 and the inner peripheral wall 89 of the receiving hole 88, and the cylindrical member 349 and the receiving hole 88 are A sealing property between them is ensured. In addition, the above-described repulsive force tightens the tubular member 349 and extends between the tubular member 349 and the core portion 343 to further increase the surface pressure of both. Hereinafter, the force with which the O-ring 352 tightens the cylindrical member 349 is referred to as a tension force.

  Here, since the central portion in the axial direction of the tubular member 349 is a portion where the O-ring 352 provided on the outer peripheral side is in close contact, the largest of the O-ring 352 is exerted. . For this reason, the surface pressure in this part becomes the largest.

  As shown in FIG. 9, an annular groove 345 is provided at a position facing the axial central portion of the inner peripheral wall 351 of the cylindrical member 349 in the outer peripheral wall 344 of the core portion 343. The groove 345 is formed at a position where the surface pressure is maximized. The width of the groove 345 in the axial direction is a predetermined length.

  By forming the groove 345, a space is formed between the tubular member 349 and the core portion 343, and the influence of the tightening force and the tightening force is reduced, and the surface pressure in this portion is reduced. The surface pressure is smaller than the surface pressure generated when the O-ring 352 is in close contact with the outer peripheral wall 350 of the cylindrical member 349 and the inner peripheral wall 89 of the accommodation hole 88.

  Next, the operation of the pressure holding mechanism 340 will be described.

  According to the above-described configuration, immediately after the high-pressure fuel pump 3 is stopped, the fuel pressure in the pressurizing chamber 18 decreases, so that the pressure on the delivery pipe 4 side and the pressure on the pressurizing chamber 18 side in the pressure holding mechanism 340 are reduced. A large differential pressure is generated. At this time, the discharge valve 20 is maintained in a state where the discharge passage 83 is closed.

  As described above, the surface pressure generated between the cylindrical member 349 and the core portion 343 of the pressure holding mechanism 340 is smaller than the surface pressure applied to the cylindrical member 349 and the accommodation hole 88 in the O-ring 352. 4 flows into the accommodation hole 88 through the return passage 85 on the discharge passage 83 side, and further attempts to enter the gap between the cylindrical member 349 having a low surface pressure value and the core portion 343. To do.

  In the state where the differential pressure is large, the fuel pressure of the delivery pipe 4 is high, and the cylindrical member 349 is formed of a material richer in elastic force than the core portion 343, so that the fuel pressure of the high-pressure fuel is the cylindrical member. The cylindrical member 349 is elastically deformed by overcoming the surface pressure generated between the 349 and the core portion 343. As a result, the gap is expanded by the fuel pressure, and the high-pressure fuel in the delivery pipe 4 flows out to the pressurizing chamber 18 side through the gap.

  Thus, even after the high-pressure fuel pump 3 is stopped, the high-pressure fuel in the delivery pipe 4 is pressurized on the low-pressure side via the pressure holding mechanism 340 even when the discharge valve 20 closes the discharge passage 83. It can escape to the chamber 18.

  Further, since the cylindrical member 349 is formed of a material having a higher elastic force than the core portion 343 as described above, the surface where the differential pressure decreases and becomes a predetermined value or less is generated between the two. When the pressure exceeds the fuel pressure of the delivery pipe 4, the formed gap is automatically closed. By closing the gap, the fuel is prevented from progressing toward the pressurizing chamber 18 and the outflow of fuel is stopped. As a result, the fuel pressure on the delivery pipe 4 side is kept above the feed pressure. As a result, when the high-pressure fuel pump 3 is started again, the fuel pressure in the delivery pipe 4 can be increased to the fuel pressure during normal operation in a short time.

  In the present embodiment, since the core 343, the cylindrical member 349, and the O-ring 352 constituting the pressure holding mechanism 340 are all circular in cross section, it is easy to manufacture and procure each part, and the manufacturing cost is reduced. The rise can be suppressed.

  As described above, in this embodiment, the pressure holding mechanism 340 includes only the core portion 343, the cylindrical member 349, and the O-ring 352 that form a gap that communicates between the delivery pipe 4 side and the pressurizing chamber 18 side. The flow and stop of the fuel can be controlled. That is, in this embodiment, the springs 51 and 151 that urge the valve needles 47, 147, and 147a required in the first and second embodiments in the valve closing direction are not separately required. According to this embodiment, since it is not necessary to separately provide these parts, the structure of the pressure holding mechanism 340 can be simplified.

  Further, according to the structure of the pressure holding mechanism 340 of this embodiment, the gap communicating between the delivery pipe 4 side and the pressurizing chamber 18 side is such that the opening and closing of the gap can be controlled by the fuel pressure that enters. Therefore, the size of the gap can be made smaller than the gap formed by providing the rigid objects close to each other as in the first to third embodiments. According to this, the leakage amount of the fuel flowing out to the pressurizing chamber 18 side through the gap can be reduced as much as possible, and when the high-pressure fuel pump 3 is operated, the discharged fuel passes through the return passage 85 and is again in the pressurizing chamber. A reduction in volumetric efficiency of the high-pressure fuel pump 3 due to returning to 18 can be suppressed.

  In this embodiment, the elastic member of the claims is composed of a cylindrical member 349 and an O-ring 352, and the high-pressure fuel of the delivery pipe 4 is supplied from only between the core portion 343 and the cylindrical member 349 to the pressurizing chamber 18. Spilled into Thereby, the circumferential length of the clearance through which the high-pressure fuel flows can be shortened. Further, since the amount of fuel leaking from the delivery pipe 4 side to the pressurizing chamber 18 side can be limited as much as possible, the high-pressure fuel on the delivery pipe 4 side flows out to the pressurizing chamber 18 side more than intended. This can be suppressed.

  By the way, there are various types of vehicles on which the fuel system including the high-pressure fuel pump 3 is mounted or the specifications of the internal combustion engine 7. For this reason, the length (volume) of the fuel piping of the fuel system, the heat received by the fuel piping from the internal combustion engine 7 and the state of heat dissipation of the fuel piping also vary depending on the type of vehicle and the specifications of the internal combustion engine 7.

  For this reason, the amount of fuel leakage required for the pressure holding mechanism 340 differs depending on the type of vehicle on which the high-pressure fuel pump 3 is mounted and the specifications of the internal combustion engine 7. Further, the value of the fuel pressure (holding pressure) to be maintained after the fuel pressure is lowered also varies depending on the type of vehicle and the specifications of the internal combustion engine 7.

  In this embodiment, it is possible to easily adjust the amount of fuel leakage and the holding pressure that differ depending on the type of vehicle and the specifications of the internal combustion engine 7. Specifically, the leakage amount and the holding pressure can be easily adjusted by adjusting the surface pressure generated between the inner peripheral wall 351 of the cylindrical member 349 and the outer peripheral wall 344 of the core portion 343.

  According to the structure of the pressure holding mechanism 340 of the present embodiment, when the fuel pressure of the delivery pipe 4 exceeds the surface pressure generated between the cylindrical member 349 and the core portion 343, a gap is formed between the two. The fuel flows out into the pressurizing chamber 18. If the surface pressure relative to the fuel pressure of the delivery pipe 4 is small, the size of the gap formed will increase, the flow resistance of the fuel flowing through this gap will decrease, and the amount of fuel leakage flowing into the pressurizing chamber 18 will be Increase. On the contrary, if the surface pressure is large, the size of the gap formed is reduced, the flow resistance of the fuel flowing through the gap is increased, and the amount of fuel leakage is reduced.

  When the fuel pressure of the delivery pipe 4 is inferior to the surface pressure, the formed gap is automatically closed. When the gap is closed, the fuel is prevented from progressing toward the pressurizing chamber 18 and the fuel outflow stops. If the surface pressure is increased, even if the differential pressure between the delivery pipe 4 and the pressurizing chamber 18 is large, the outflow of fuel to the pressurizing chamber 18 side can be stopped, so the holding pressure is increased. Can do. On the other hand, if the surface pressure is reduced, the pressure difference between the delivery pipe 4 and the pressurizing chamber 18 becomes the fuel pressure in the pressurizing chamber 18 so that the holding pressure can be lowered.

  According to this configuration, a member that forms a gap (in this embodiment, only the surface pressure of the cylindrical member 349 and the core portion 343 is adjusted, and the amount of fuel leakage and the holding pressure are adjusted without using other members. be able to.

  Generally, when a fluid flows through a minute gap, the flow rate of the fluid flowing therethrough decreases as the flow path length is longer if the passage area and the viscosity coefficient of the fluid are the same. This is because if the flow path length is long, the flow resistance of the fluid flowing therethrough increases and restricts the flow of the fluid.

  In this embodiment, this is utilized to adjust the fuel leakage amount and holding pressure by adjusting the axial length of the cylindrical member 349. Specifically, by increasing the length of the cylindrical member 349, the amount of fuel leakage is reduced and the holding pressure is increased. According to this configuration, the amount of fuel leakage and the holding pressure can be adjusted by a simple means of adjusting the axial length of the cylindrical member 349.

  Hereinafter, a method for adjusting the surface pressure generated between the cylindrical member 349 and the core portion 343 will be specifically described.

  In the present embodiment, the surface pressure generated between the two is determined by the outer diameter D of the core portion 343 and the inner diameter d of the inner peripheral wall 351 of the tubular member 349, the tightening force of the O-ring 352, and the core. It is adjusted by adjusting the size of the groove 345 formed in the outer peripheral wall 344 of the portion 343.

  The surface pressure can be increased by increasing the tightening allowance. Further, the surface pressure can be increased by increasing the tightening force of the O-ring 352. The tightening force can be increased by increasing the wire diameter or inner diameter of the O-ring 352.

  Further, the O-ring 352 has a wire diameter and an inner diameter that are inserted into the receiving hole 88 and sufficiently immersed in fuel, so that both ends of the O-ring 352 in the axial direction extend from both ends of the cylindrical member 349 in the axial direction. The size does not protrude. According to this, both end portions in the axial direction of the O-ring 352 protrude from both end portions in the axial direction of the cylindrical member 349, so that it is impossible to appropriately apply the tightening force of the O-ring 352 to the cylindrical member. This can be suppressed.

  Further, in the present embodiment, as shown in FIG. 9, the washer 353 and the large-diameter portion 347 of the plug 341 are disposed so as to be close to both ends of the cylindrical member 349 and the O-ring 352 in the axial direction. According to this, it can suppress that the axial direction edge part of O-ring 352 protrudes from the axial direction both ends of the cylindrical member 349, and gives the cylindrical member 349 the compression force of O-ring 352 appropriately. Can do. The washer 353 and the large-diameter portion 347 of the plug 341 correspond to the stopper portion described in the claims.

  The surface pressure can be reduced by increasing the axial width of the groove 345. In this embodiment, since the groove 345 is formed in an annular shape, the position to be adjusted is only the width in the axial direction, but if the groove 345 is not annular and has a predetermined length in the circumferential direction, The surface pressure can be adjusted by adjusting both the axial and circumferential widths. At this time, the surface pressure can be reduced by increasing the axial and circumferential widths.

  Hereinafter, a plurality of modifications of the method for adjusting the surface pressure generated between the cylindrical member 349 and the core portion 343 will be described in detail.

(Modification 1)
FIG. 11 shows an example in which the groove 345 formed in the core portion 343 of the fourth embodiment is eliminated. In this case, as described above, the surface pressure is adjusted by adjusting the tightening allowance between the cylindrical member 349 and the core portion 343 or the tightening force of the O-ring 352.

(Modification 2)
FIG. 12 shows an example in which the groove 345 formed in the core portion 343 of the fourth embodiment is eliminated and a groove 351a is formed in the inner peripheral wall 351 of the cylindrical member 349 instead. Even in this case, as in the fourth embodiment, the surface pressure is adjusted by adjusting the tightening allowance, the tightening force of the O-ring 352, or the axial or circumferential width of the groove 351a.

(Modification 3)
FIG. 13 shows an example in which an O-ring 352a having a rectangular cross section is used instead of the O-ring 352 having a circular cross section in the fourth embodiment. Since the cross section of the O-ring 352a is rectangular, the distribution of the tension force can be made uniform as compared with a circular cross section.

  As described above, the fuel leakage amount and the holding pressure can be adjusted by the methods of the fourth embodiment and the first to third modifications. The method for adjusting the leakage amount and the holding pressure is not limited to the individual methods described in the fourth embodiment and the first to third modifications. For example, modification 2, modification 3, and modification 4 may be combined with the fourth embodiment, or modifications may be combined.

(Fifth embodiment)
FIG. 14 shows a fifth embodiment of the present invention. In addition, in the high-pressure fuel pump 3 according to the fifth embodiment described below, the same reference numerals are given to substantially the same components as those in the fourth embodiment, and description thereof will be omitted.

  In the fifth embodiment shown in FIG. 14, the washer that regulates the protruding from the axial end of the cylindrical member 349 of the cylindrical member 349 of the cylindrical member 349 and the O-ring 352 and the cylindrical member 349 of the fourth embodiment. 353 is integrated. Thereby, the number of parts of the pressure holding mechanism 440 can be reduced as compared with that of the fourth embodiment, and the pressure holding mechanism 440 can be easily assembled.

  In this embodiment, the plug 441 and the core portion 446 are separate. An insertion hole 444 for inserting the core portion 446 is formed in the axial direction at the end portion of the plug 441 on the core portion 446 side. The constricted portion 442 of the plug 441 is formed with a through hole 445 that penetrates the insertion hole 444 in the radial direction.

  The core portion 446 extends in the axial direction, and extends in the radial direction from the insertion portion 447 inserted into the insertion hole 444, and a circle that restricts the protrusion of the O-ring 352 from the axial end portion of the cylindrical member 349. And a plate portion 448. The cylindrical member 349 and the O-ring 352 are disposed between the disc portion 448 and the large diameter portion 443 of the plug 441. Note that the relationship between the insertion hole 444 and the insertion portion 447 is a clearance fit.

  The fuel that has flowed into the accommodation hole 88 from the delivery pipe 4 passes through a gap formed between the cylindrical member 349 and the insertion part 447 in the core part 446, and further passes through a gap between the insertion hole 444 and the insertion part 447. , Flows out into the through hole 445. The fuel that has flowed into the through hole 445 returns to the pressurizing chamber 18 from the constricted portion 442 through the return passage 85 on the pressurizing chamber 18 side. Also in this embodiment, the amount of fuel leakage and the holding pressure of the pressure holding mechanism 440 can be adjusted by the same method as in the fourth embodiment and its first to third modifications.

  According to this configuration, it is not necessary to prepare a stopper 354 that prevents the washer 353 having the same function as the disc portion 448 of the present embodiment from being provided as in the fourth embodiment, so that the components of the pressure holding mechanism 440 are eliminated. The score can be reduced.

  Further, according to this configuration, the pressure holding mechanism 440 can be easily assembled only by inserting the core portion 446 in which the cylindrical member 349 and the O-ring 352 are assembled into the insertion portion 447 into the insertion hole 444 of the plug 441. it can.

(Sixth embodiment)
A sixth embodiment of the present invention is shown in FIGS. In the high-pressure fuel pump 3 according to the sixth embodiment described below, the same reference numerals are given to substantially the same components as those in the fourth embodiment, and description thereof will be omitted.

  The sixth embodiment shown in FIGS. 15 and 16 is a relief that protects the fuel system by allowing a part of the fuel in the delivery pipe 4 to escape to the pressurizing chamber 18 when the fuel pressure in the delivery pipe 4 becomes an abnormally high pressure state. The example which accommodated the pressure holding mechanism 540 in the valve 30 is shown.

  As shown in FIGS. 15 and 16, the relief valve 30 includes a valve seat 31, a valve body 32, a stopper 35, a spring 36, and a pressure holding mechanism 540, and is provided in an accommodation hole 88 formed in the middle of the return passage 85. Contained. In this embodiment, the accommodation hole 88 and the return passage 85 correspond to the relief passage described in the claims.

  The valve seat 31 is formed at the periphery of the opening of the return passage 85 formed at the bottom of the accommodation hole 88. The valve body 32 is supported in the housing hole 88 so as to be slidable in the axial direction. The stopper 35 is formed in a substantially cylindrical shape, is provided closer to the opening of the housing hole 88 than the valve body 32, and closes the opening of the housing hole 88.

  The spring 36 is provided between the stopper 35 and the valve body 32 and biases the valve body 32 in the valve closing direction. The biasing force of the spring 36 is such that the valve can be kept closed until the fuel pressure in the delivery pipe 4 exceeds the abnormal pressure.

  When the fuel pressure of the delivery pipe 4 exceeds the abnormal pressure and the force acting on the tip of the valve body 32 exceeds the urging force of the spring 36, the valve body 32 moves to the opening side of the accommodation hole 88 and the valve seat 31. Get away from. As a result, the discharge passage 83 and the pressurizing chamber 18 communicate with each other, and the high-pressure fuel in the delivery pipe 4 returns to the pressurizing chamber 18.

  Next, the structure of the valve body 32 of the relief valve 30 will be described in more detail with reference to FIG. The valve body 32 includes a valve member 131 and a spring receiving member 541, and houses a pressure holding mechanism 540 therein.

  The valve member 131 is formed in a substantially cylindrical shape, and has a large diameter portion 132 and a small diameter portion 133 having different outer diameters. A through hole 134 is formed in the valve member 131. The inner diameter of the through hole 134 is smaller on the small diameter portion 133 side than on the large diameter portion 132 side.

  A spring receiving member 541 is fitted into the opening of the through hole 134 on the large diameter portion 132 side by press-fitting. The spring receiving member 541 has a seat portion 542 that receives one end of the spring 36, and a core portion 543 that supports the tubular member 349 and the O-ring 352.

  The seat portion 542 is formed in a substantially disc shape, and is fitted into the opening of the through hole 134 on the large diameter portion 132 side by press-fitting. The seat 542 is formed with a passage hole 544 that penetrates both end faces.

  The core portion 543 extends toward the through hole 134 from the end surface of the seat portion 542 on the valve member 131 side. The tip of the core part 543 reaches the opening of the through hole 134 on the small diameter part 133 side. The relationship between the through hole 134 on the small diameter portion 133 side and the core portion 543 is a clearance fit.

  A cylindrical member 349 and an O-ring 352 are accommodated in a space formed between the seat portion 542 and the through hole 134. The O-ring 352 seals between the outer peripheral wall 350 of the cylindrical member 349 and the inner peripheral wall 135 of the through hole 134.

  The fuel that has flowed into the accommodation hole 88 from the delivery pipe 4 passes through a gap formed between the core portion 543 and the through hole 134 of the valve member 131 and enters the space in which the cylindrical member 349 and the O-ring 352 are accommodated. Inflow. The fuel that has flowed into the space flows out to the opening side of the accommodation hole 88 of the valve body 32 through the gap formed between the tubular member 349 and the core portion 543 and the passage hole 544. The fuel that has flowed out returns to the pressurizing chamber 18 through the return passage 85 on the pressurizing chamber 18 side. Also in this embodiment, the amount of fuel leakage and the holding pressure of the pressure holding mechanism 540 can be adjusted by the same method as in the fourth embodiment and its first to third modifications.

  In this embodiment, the passage from the through hole 134 formed in the valve member 131 to the passage hole 544 formed in the seat portion 542 of the spring receiving member 541 corresponds to the second passage described in the claims. .

(Seventh embodiment)
A seventh embodiment of the present invention is shown in FIG. In the high-pressure fuel pump 3 according to the seventh embodiment described below, the same reference numerals are given to substantially the same components as those in the first and fourth embodiments, and the description thereof will be omitted.

  The seventh embodiment shown in FIG. 17 shows an example in which a pressure holding mechanism 640 is accommodated in the discharge valve 20. As shown in FIG. 17, the valve body 121 of the discharge valve 20 is formed in a substantially cylindrical shape, and has an outer wall having a bottom portion 122 that is attached to and detached from the valve seat 21 of the discharge passage 83. The valve body 121 is supported by the discharge passage 83 so as to be slidable in the axial direction. The pressure holding mechanism 640 is accommodated in the valve body 121.

  On the inner peripheral side of the valve body 121, a fuel passage 126 communicating with the outlet portion 84 is formed by the side wall 124 of the valve body 121. The side wall 124 is formed with a through hole 125 that communicates the outer wall of the valve body 121 and the fuel passage 126. Thereby, when the bottom 122 is separated from the valve seat 21, the high-pressure fuel that has flowed from the pressurizing chamber 18 to the outer wall side of the side wall 124 flows into the fuel passage 126 through the through hole 125. Then, the high-pressure fuel that has flowed into the fuel passage 126 is supplied to the delivery pipe 4 from the outlet 84 (see FIG. 3).

  A spring 28 is provided between the stopper 27 and the valve body 121 to urge the valve body 121 in the valve closing direction. When a differential pressure is generated between the pressurizing chamber 18 side and the outlet portion 84 side of the valve body 121 and the force acting on the bottom portion 122 of the valve body 121 exceeds the urging force of the spring 28, the valve body 121 moves to the valve seat 21. The pressurizing chamber 18 and the outlet 84 communicate with each other.

  A spring receiving member 641 is fitted into the valve body 121 by press fitting. The spring receiving member 641 is press-fitted on the inner peripheral side of the side wall 124 of the valve body 121, and a seat 642 that receives one end of the spring 28 that urges the valve body 121 in the valve closing direction, and a tubular member 349. And a core portion 643 that supports the O-ring 352.

  The seat portion 642 is formed in a substantially disc shape, and is fitted into the inner peripheral side of the side wall 124 of the valve body 121 by press-fitting. The seat portion 642 is formed with a passage hole 644 that penetrates both end surfaces.

  The core portion 643 extends from the end surface of the seat portion 642 on the bottom portion 122 side toward the through hole 123 formed in the bottom portion 122. The leading end of the core portion 643 reaches the through hole 123. In addition, the relationship between the through-hole 123 and the core part 643 is a clearance fit.

  A cylindrical member 349 and an O-ring 352 are accommodated in a space formed between the seat portion 642 and the bottom portion 122. The O-ring 352 seals between the outer peripheral wall 350 of the cylindrical member 349 and the inner peripheral wall 127 of the side wall 124.

  The fuel that has flowed into the fuel passage 126 from the delivery pipe 4 passes through the passage hole 644 of the seat portion 642 and flows into the space in which the tubular member 349 and the O-ring 352 are accommodated. The fuel that has flowed into the space passes through the gap formed between the cylindrical member 349 and the core portion 643 and the gap formed between the core portion 643 and the through hole 123 from the bottom portion 122 to the pressurizing chamber 18. To the side. The fuel that has flowed out returns to the pressurizing chamber 18 through the discharge passage 83. Also in this embodiment, the fuel leakage amount and holding pressure of the pressure holding mechanism 640 can be adjusted by the same method as in the fourth embodiment and its first to third modifications.

  In this embodiment, the through hole 123 formed in the bottom 122 of the valve body 121 passes through the passage hole 644 formed in the seat 642 of the spring receiving member 641 and is formed on the inner peripheral side of the valve body 121. The passage to the fuel passage 126 is equivalent to the second passage described in the claims.

(Eighth and ninth embodiments)
Eighth and ninth embodiments of the present invention are shown in FIGS. Note that, in the high-pressure fuel pump 3 according to the eighth and ninth embodiments described below, the same reference numerals are given to substantially the same components as those of the fourth and sixth embodiments, and description thereof will be omitted.

  In the eighth and ninth embodiments shown in FIGS. 18 and 19, instead of the return passage 85 on the pressurizing chamber 18 side where the accommodating hole 88 and the pressurizing chamber 18 are connected, the accommodating hole 88 and the pressurizing chamber are used. 18 shows an example in which a low-pressure passage 85a that connects a low-pressure portion (for example, the suction chamber 91 and the fuel tank 6) disposed on the upstream side of 18 is shown. The fuel that has flowed out of the pressure holding mechanisms 340 and 540 when the high-pressure fuel pump 3 is stopped returns to the low-pressure portion through the low-pressure passage 85a.

  According to these embodiments, the low pressure passage 85a is not connected to the pressurizing chamber 18, but is connected to the suction chamber 91 and the fuel tank 6, so that the degree of freedom of installation of the low pressure passage 85a is increased. Can do. Thereby, an increase in manufacturing cost can be suppressed.

(10th Embodiment)
A tenth embodiment of the present invention is shown in FIGS. Note that, in the high-pressure fuel pump 3 according to the tenth embodiment described below, the same reference numerals are given to substantially the same components as those in the fourth embodiment, and description thereof will be omitted.

  10th Embodiment shown in FIG. 20 has shown the example comprised only by the cylindrical member 749 as an elastic member as described in a claim. FIG. 21 is an exploded view of the pressure holding mechanism 740 of this embodiment.

  Also with this configuration, the same effect as in the fourth embodiment can be obtained. Specifically, the cylindrical member 749 supported by the outer peripheral wall 744 of the core portion 743 is also supported by the inner peripheral wall 89 of the accommodation hole 88. Predetermined surface pressure is generated between the inner peripheral wall 751 of the cylindrical member 749 and the outer peripheral wall 744 of the core portion 743 and between the outer peripheral wall 750 of the cylindrical member 749 and the inner peripheral wall 89 of the accommodation hole 88. is doing.

  In this embodiment, unlike the fourth embodiment, the fuel passing through the pressure holding mechanism 740 flows between the inner peripheral wall 751 of the cylindrical member 749 and the outer peripheral wall 744 of the core portion 743, and the outer peripheral wall of the cylindrical member 749. It passes between 750 and the inner peripheral wall 89 of the accommodation hole 88.

  In this embodiment, as shown in FIGS. 20 and 21, the inner diameter of the inner peripheral wall 751 of the cylindrical member 749 is d1 and the outer diameter of the outer peripheral wall 750 is the state before the cylindrical member 749 is assembled to the core 743. d2, the outer diameter of the core portion 743 is D1, and the inner diameter of the inner peripheral wall 89 of the accommodation hole 88 is D2, the inner diameter d1 is smaller than the outer diameter D1, and the outer diameter d2 is larger than the inner diameter D2. .

  Thereby, predetermined surface pressure can be generated between the cylindrical member 749 and the core portion 743 and between the cylindrical member 749 and the accommodation hole 88, respectively. Further, these surface pressures are adjusted by adjusting an inner peripheral side allowance that is a difference between the outer diameter D1 and the inner diameter d1 and an outer peripheral side allowance that is a difference between the outer diameter d2 and the inner diameter D2. Can do. Thereby, the amount of fuel leakage and the holding pressure can be adjusted. The amount of fuel leakage and the holding pressure can also be adjusted by adjusting the axial length of the cylindrical member 749.

  In addition, although this embodiment demonstrated as other embodiment in 4th Embodiment, you may apply the pressure holding mechanism 740 which has this structure to 6th-9 embodiment.

1 is a system configuration diagram of a fuel supply system including a high-pressure fuel pump according to a first embodiment of the present invention. It is sectional drawing of a high pressure fuel pump. It is a fragmentary sectional view of the III-III line in FIG. It is sectional drawing of the relief valve of the high pressure fuel pump shown in FIG. 2 and FIG. It is sectional drawing of the discharge valve of the high pressure fuel pump by 2nd Embodiment of this invention. It is sectional drawing which shows the modification of the discharge valve of the high pressure fuel pump by 2nd Embodiment. It is a fragmentary sectional view of the high-pressure fuel pump by a 3rd embodiment of the present invention. It is a fragmentary sectional view of the high-pressure fuel pump by a 4th embodiment of the present invention. It is sectional drawing of the pressure holding mechanism in the high pressure fuel pump by 4th Embodiment. FIG. 10 is an exploded view of the pressure holding mechanism shown in FIG. 9. It is sectional drawing which shows the modification 1 of the pressure holding mechanism in the high pressure fuel pump by 4th Embodiment. It is sectional drawing which shows the modification 2 of the pressure holding mechanism in the high pressure fuel pump by 4th Embodiment. It is sectional drawing which shows the modification 3 of the pressure holding mechanism in the high pressure fuel pump by 4th Embodiment. It is sectional drawing of the pressure holding mechanism in the high pressure fuel pump by 5th Embodiment of this invention. It is a fragmentary sectional view of the high pressure fuel pump by a 6th embodiment of the present invention. It is sectional drawing of the relief valve and pressure holding mechanism in the high pressure fuel pump by 6th Embodiment. It is sectional drawing of the discharge valve and pressure holding mechanism in the high pressure fuel pump by 7th Embodiment of this invention. It is a fragmentary sectional view of the high pressure fuel pump by an 8th embodiment of the present invention. It is a fragmentary sectional view of the high pressure fuel pump by a 9th embodiment of the present invention. It is sectional drawing of the pressure holding mechanism of the high pressure fuel pump by 10th Embodiment of this invention. FIG. 21 is an exploded view of the pressure holding mechanism shown in FIG. 20.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Fuel supply system, 2 Low pressure fuel pump, 3 High pressure fuel pump, 4 Delivery pipe (accumulation chamber), 5 Fuel injection valve, 6 Fuel tank, 7 Internal combustion engine, 11 Plunger, 15 Spring, 18 Pressurization chamber, 20 Discharge valve , 21 Valve seat, 22 Valve body, 25 Fuel passage, 26 Through hole, 27 Stopper, 28 Spring, 30 Relief valve, 31 Valve seat, 32 Valve body, 35 Stopper, 36 Spring, 40 Pressure holding mechanism, 41 Fuel passage, 42 Large-diameter passage, 43 Small-diameter passage, 44 Valve seat, 45 Through hole, 46 Inner wall, 47 Valve needle, 48 Valve body portion, 49 Tube portion, 50 Sliding portion, 51 Spring, 52 Stopper, 60 Metering valve, 61 Valve seat member, 62 Valve seat, 63 Valve member, 64 Valve closing spring, 65 Spring seat, 66 Electromagnetic drive, 80 (Housing), 81 sliding portion, 82 suction passage, 83 discharge passage (first passage), 84 outlet portion, 85 return passage, 86 escape passage, 87 housing hole, 88 housing hole, 90 housing cover (housing), 91 Suction chamber

Claims (4)

In the high-pressure fuel pump that pressurizes the fuel and pumps it toward the pressure accumulator chamber,
A housing having a pressurizing chamber and a first passage communicating the pressurizing chamber and the pressure accumulating chamber;
A plunger that is accommodated in the housing so as to be reciprocally movable and pressurizes the fuel sucked into the pressurizing chamber;
A discharge valve that is provided in the first passage and opens when the pressure in the pressurizing chamber becomes equal to or higher than a predetermined pressure, and supplies a fuel in the pressurizing chamber to the pressure accumulating chamber;
A second passage communicating the pressure accumulation chamber side and the pressure chamber side of the discharge valve, the second passage having a valve seat in the middle of the passage;
A valve body seated on the valve seat so as to allow only the flow of fuel from the pressure accumulating chamber side to the pressurizing chamber side;
A biasing means for biasing the valve body in a seating direction;
A throttle part that is provided in the middle of the second passage and restricts the flow of fuel from the pressure accumulating chamber side to the pressurizing chamber side,
The diaphragm portion is Ri gap der formed between the side wall and the inner wall of the second passage of the valve body,
The housing has a relief passage in which one is communicated with the first passage closer to the pressure accumulation chamber than the discharge valve, and the other is communicated with the first passage closer to the pressurization chamber than the discharge valve. Formed,
A relief valve is provided in the relief passage to open the pressure in the pressure accumulating chamber to the pressurizing chamber when the pressure accumulating chamber is in an abnormally high pressure state.
The high-pressure fuel pump , wherein the second passage is formed inside a valve body of the relief valve .   2. The high-pressure fuel according to claim 1, wherein the side wall of the valve body is a sliding portion that slides with the inner wall of the second passage so that the valve body is guided in a seating direction. 3. pump. The valve body has a valve body portion seated on the valve seat, and a cylinder portion extending from the valve body portion along the axial direction of the second passage,
The high-pressure fuel pump according to claim 2, wherein the cylindrical portion has an outer diameter smaller than that of the valve body portion, and the sliding portion is formed on a side wall.   4. The high-pressure fuel pump according to claim 1, wherein the cylindrical portion is disposed closer to the pressure accumulating chamber than the valve seat. 5.

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