JP4325546B2 - Fuel injection valve - Google Patents

Description

  The present invention relates to a fuel injection valve, and is suitably applied to, for example, a fuel injection valve that injects and supplies fuel to an internal combustion engine.

  As a fuel injection device, for example, a fuel injection valve that directly or indirectly injects fuel into a combustion chamber of an internal combustion engine is known. The fuel supplied from the fuel injection valve is mixed with air in the intake pipe or the combustion chamber to form a combustible mixture in the combustion chamber. The combustible air-fuel mixture in the combustion chamber is compressed by piston motion, and then ignited and combusted by an ignition device, and is used as power for the internal combustion engine.

  This type of fuel injection valve includes a valve body, a valve portion having a needle as a valve member that can be seated on and separated from the valve seat, a movable core that cooperates with the needle, and electromagnetic generated in a drive coil An electromagnetic drive unit having a fixed core that magnetically attracts the movable core using force, and the fuel injection amount is a period during which the needle is separated from the valve seat, that is, a valve opening period, and between the movable core and the fixed core There is known one that is quantitatively controlled by a so-called needle lift amount corresponding to the air gap (see Patent Document 1).

  For example, when fuel is directly injected into the combustion chamber by means of a fuel injection valve, the fuel injection valve is generally arranged such that the tip side of the valve body faces the combustion chamber. On the other hand, an internal working member such as a needle is immersed in a fuel having a relatively small temperature change. For this reason, a temperature difference may occur between the needle side and the valve body side, that is, the inside and outside of the fuel injection valve, due to the influence of the ambient temperature such as the combustion temperature. In some cases, if the temperature difference between the valve body and the internal working member such as the needle increases, the lift amount changes due to the difference in thermal expansion, and the fuel injection amount changes. There is a demand for valves.

As a means for realizing this, in Patent Document 1, the temperature of an outer member such as a valve body that contacts the engine side is measured or predicted, and the deviation of the fuel injection amount due to the temperature is calculated by a control device such as an ECU to eliminate the deviation. A technique for correcting the fuel injection amount is disclosed.
Japanese Patent Laid-Open No. 10-274076

  In the prior art disclosed in Patent Document 1, it is possible to correct and control the deviation of the fuel injection amount due to the influence of the ambient temperature. In reality, however, the individual fuel injectors shipped from the factory vary in the amount of lift, the needles, the materials that make up the valve body, and so on. There is a problem that it is difficult to prevent a fuel injection amount change due to heat reception, that is, a lift amount change.

  The present invention has been made in consideration of such circumstances, and the object thereof is to include an internal working member of the valve member and an outer member such as a valve body, and the lift amount of the valve member and the valve opening period. An object of the present invention is to provide a fuel injection valve capable of preventing a change in lift amount even when the fuel injection amount is adjusted and the valve body and the like are affected by the ambient temperature due to heat reception.

  In order to achieve the above object, the present invention comprises the following technical means.

That is, according to the first to fourth aspects of the present invention, there is provided a valve body having a valve seat, which is used in an internal combustion engine having a combustion chamber in a cylinder and injecting and supplying fuel to the combustion chamber. A valve member that is accommodated so as to be movable in the axial direction and that is seated on and away from the valve seat, and an electromagnetic drive unit that is fixed to the valve body side and that drives the valve member by magnetic action, and is separated from the valve seat A fuel injection valve that determines a fuel injection amount to be supplied to the combustion chamber based on a lift amount of the valve
A lift correction mechanism for correcting a difference in thermal expansion between the valve body side and the valve member side, and defining a lift amount of the valve member;
The lift compensation mechanism is made up of a lift stopper that regulates the lift amount of the valve member and a material that has a smaller thermal expansion coefficient than the valve body, and one end abuts against the lift stopper and the other end abuts against the valve body. And a biasing member that maintains the contact state between the lift correction member and the valve body by biasing the lift stopper toward the lift correction member. In addition, the valve body side and the valve member side are corrected by following the valve body via the lift correction member, and the lift amount of the valve member is defined.

According to this, Ru with a lift correction mechanism for correcting the lift change in the difference in thermal expansion between the valve body side and the valve member. Lift correction mechanism, so defines the lift of the valve member, that Hakare alleviation or prevention of the lift change in the difference in thermal expansion between the valve body side and the valve member side by the internal combustion engine side effects such as combustion in the combustion chamber . The lift correction mechanism can maintain the lift amount of the valve member at a predetermined value even when the lift correction mechanism is affected by the ambient temperature due to heat received by the fuel injection valve.

  For example, in a fuel injection valve that is arranged such that the front end side of the valve body faces the combustion chamber, a difference in thermal expansion occurs between the valve member inside and the valve body housing the valve member inside. Even if there is a case, the lift correction member prevents the lift amount from changing.

  Therefore, even when the valve body or the like is affected by the ambient temperature due to heat reception, it is possible to prevent the lift amount from changing.

Lift correction mechanism includes a lift correction member, a lift stopper for restricting the lift amount of the valve member, so and a biasing member for biasing the lift stopper to lift correction member side, the valve body side and the valve member side The axial position of the lift correction member is changed so as to reduce or prevent the thermal expansion difference, and the lift stopper can follow the change in the axial position of the lift correction member by the biasing force of the biasing member. Therefore, even if it is a case where it receives to the influence of ambient temperature, it can prevent that the lift amount of a valve member changes.

According to the second aspect of the present invention, the electromagnetic drive unit includes a movable core that cooperates with the valve member and a fixed core that magnetically attracts the movable core, and the movable core is formed so that the lift correction member can be inserted therethrough. It is characterized by being.

  In general, an electromagnetic drive unit that drives a valve member by a magnetic action includes a movable core that cooperates with the valve member and a fixed core that magnetically attracts the movable core. The maximum movement amount of the movable core, that is, the lift amount is determined by the movement amount sucked to the fixed core side.

On the other hand, in the invention according to claim 2 , since the lift correction member is arranged so that the movable core can be inserted, the lift movement of the movable core, that is, the lift amount of the valve member is regulated by the lift correction member. Can do.

The invention according to claim 3 is characterized in that a lift stopper is disposed between the movable core and the fixed core.

  According to this, since the lift stopper is disposed between the movable core and the fixed core, the maximum movement amount of the movable core, that is, the lift amount of the valve member can be defined by the axial position of the lift stopper. Therefore, even if it is affected by the ambient temperature, a change in the lift amount of the valve member can be prevented at the position of the lift stopper in which the difference in thermal expansion between the valve body side and the valve member side is corrected by the lift correction member. .

According to a fourth aspect of the present invention, the valve body has a housing connected to the electromagnetic drive unit, and the upper end of the valve body is disposed inside the housing.

  Generally, the valve seat of the valve body is required to have relatively high wear resistance because the valve member is repeatedly seated and separated for each fuel injection.

On the other hand, in the invention according to claim 4 , the valve body side portion of the valve body is made of a specific material having relatively high wear resistance, and the housing on the side connected to the electromagnetic drive unit is specified. For example, an inexpensive material other than the material can be used.

  Furthermore, since the upper end portion of the valve body is disposed inside the housing, for example, one of the axial end portions of the lift correction member can be brought into contact with the upper end portion of the valve body. As a result, the axial position of the lift correction member can be changed so as to reduce or prevent a change in lift due to a difference in thermal expansion between the valve body side and the valve member side.

  Hereinafter, the fuel injection device according to the present invention is applied to an apparatus that injects and supplies fuel to a gasoline engine, and a specific embodiment will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a cross-sectional view showing a schematic configuration of the fuel injection valve of the present embodiment. 2 is a partially enlarged view of FIG. 1. FIG. 2 (a) is a partial cross-sectional view showing the periphery of the movable core and the fixed core, and FIG. 2 (b) is a partial cross-sectional view showing the periphery of the valve member and the valve body. It is. FIG. 3 is a schematic cross-sectional view showing the positional relationship between the lift correction member and the movable core as viewed from III-III in FIG. FIG. 5 is a schematic cross-sectional view showing a state in which the fuel injection valve of the comparative example is mounted on the internal combustion engine. In the mounted state of the internal combustion engine in FIG. 5, both the fuel injection valve of the comparative example and the fuel injection valve of the present embodiment are mounted with a known structure. Hereinafter, the description of the internal combustion engine will be made with reference to FIG. 5 for the sake of convenience.

  The fuel injection device is used in an internal combustion engine, particularly a gasoline engine, and injects fuel into each cylinder of, for example, a multi-cylinder (for example, four-cylinder) gasoline engine (hereinafter referred to as an engine). As shown in FIG. 5, engine 100 includes a cylinder block (not shown), a cylinder head 102, a piston (not shown), an inner peripheral wall of the cylinder block, a piston, and a ceiling inner wall of cylinder head 102. This is a well-known internal combustion engine including a combustion chamber 106 that is defined. The volume of the combustion chamber 106 increases or decreases as the piston reciprocates. The cylinder head 102 includes an intake port (not shown) that is connected to an intake pipe (not shown) and guides intake and intake air, and an exhaust port (not shown) that is connected to an exhaust pipe (not shown) and discharges exhaust gas. Yes. Here, FIG. 5 shows only one of the four cylinders in the drawing, and FIG. 1 shows a fuel injection valve provided in the cylinder shown in FIG.

  The fuel injection device includes a fuel injection valve 2 that injects fuel. The fuel injection valve 2 is not limited to a cylinder head or the like attached to the cylinder as shown in FIG. 5 but may be attached to an intake pipe or an exhaust pipe such as an intake port of the engine 100.

  The fuel injection valve 2 is supplied with fuel pressurized by a fuel pump (not shown) via a fuel distribution pipe (not shown). The fuel injection valve 2 has a substantially cylindrical shape as shown in FIG. 1, receives fuel from one end, and injects fuel from the other end. The fuel injection valve 2 includes a valve portion B that stops and stops fuel injection, an electromagnetic drive portion S that drives the valve portion B, and a lift correction member 71. An inner hole is formed in the fuel inlet portion on one end side of the fuel injection valve 2 and communicates with an internal fuel passage for supplying fuel to the valve portion B in the fuel injection valve 2. A filter is attached to the inner hole to remove foreign matter. When the engine 100 is a direct injection engine, the fuel injection valve 2 directly supplies fuel to the combustion chamber 106 of the cylinder. In this case, in order to set the pressure of the fuel supplied to the combustion chamber 106 to about 2 MPa or more, a predetermined low pressure (for example, 0.2 MPa) fuel sucked up from the fuel tank by the fuel pump is further supplied by a high pressure pump (not shown). Pressurized, and this pressurized predetermined high-pressure fuel (for example, a fuel having a predetermined pressure in the range of 2 to 13 MPa) is supplied to the fuel injection valve 2 via the fuel distribution pipe. The fuel discharged from the fuel pump and the fuel discharged after being further pressurized from the high-pressure pump are regulated to a predetermined pressure by a pressure regulator as a fuel pressure regulator (not shown).

  Note that the fuel supplied to the fuel injection valve 2 is guided from a fuel tank that is disposed relatively far from a heat source such as a cylinder having the combustion chamber 106, so that the temperature change is relatively small.

  As shown in FIG. 1, the valve part B includes a valve body 12, a needle 30 as a valve member, and a housing 16. The valve body 12 is fixed to the inner wall of the end portion of the fuel injection side of a housing (hereinafter referred to as a valve housing) 16 by welding. The valve body 12 has a conical surface 13 as an inner peripheral surface that decreases in diameter toward the nozzle hole 21 side in the fuel flow direction. The needle 30 can be separated from and seated on the conical surface 13. Here, the conical surface 13 constitutes a valve seat 14 on which the needle 30 can be separated and seated. Specifically, the contact portion 31 of the needle 30 is separated from and seated on the valve seat 14. The needle 30 is formed in a substantially shaft shape, and can reciprocate in the valve body 12 in the axial direction. Here, the valve seat 14 and the contact portion 31 constitute a seat portion that functions as an oil tight function for the valve portion to stop fuel injection.

Here, the valve housing 16 constitutes a housing according to claim 4 . The housing 16 and the valve body 12 constitute a valve body according to claims 1 to 4. In general, the valve seat 14 of the valve body is required to have relatively strong wear resistance because the needle 30 is repeatedly seated and separated for each fuel injection. On the other hand, in the present embodiment, a portion of the valve body on the valve seat 14 side, that is, the valve body 12 is connected to the electromagnetic drive unit S (specifically, the cylindrical member 40) with a specific material having relatively high wear resistance. For example, an inexpensive material other than the specific material can be used for the valve housing 16 on the side to be operated.

  The valve body is not limited to the valve body 14 side portion (specifically, the valve body 12) and the valve housing 16 connected to the electromagnetic drive unit S, which are formed as separate members and integrally assembled. Instead, they may be integrally formed.

  As shown in FIG. 1, an injection hole 21 that can communicate with the internal fuel passage is disposed on the central side of the valve seat toward the downstream side of the fuel flow of the valve seat 14. The size of the nozzle hole 21, the direction of the nozzle hole axis, the nozzle hole arrangement, and the like are determined in accordance with the required fuel spray shape, direction, number, and the like. The opening area of the nozzle hole defines the flow rate when the valve is opened. The fuel injection amount of the fuel injection valve 2 is measured by the opening area of the opened nozzle hole, the lift amount of the needle 30 and the valve opening period. When the needle 30 is seated on the valve seat 14, fuel injection from the nozzle hole 21 is stopped, and when the needle 30 is separated from the valve seat 14, fuel is injected from the nozzle hole 21.

  As shown in FIG. 1, the electromagnetic drive unit S includes a cylindrical member 40, a movable core 50, a fixed core 54, a coil 60, and a compression spring 58. The cylindrical member 40 is inserted into the inner peripheral wall of the valve housing 16 on the side opposite to the injection hole, and is fixed to the valve housing 16 by welding. Further, the cylindrical member 40 includes a first magnetic cylindrical portion 42, a nonmagnetic cylindrical portion 44, and a second magnetic cylindrical portion 46 from the nozzle hole 21 side. The nonmagnetic cylinder portion 44 prevents a magnetic short circuit between the first magnetic cylinder portion 42 and the second magnetic cylinder portion 46. By preventing the magnetic short circuit, the magnetic flux generated by the electromagnetic force generated by energization of the coil 60 efficiently flows to the movable core 50 and the fixed core 54. The movable core 50 is formed of a magnetic material in a substantially cylindrical shape, and is fixed to the end portion 34 of the needle 30 on the side opposite to the injection hole by welding. The movable core 50 reciprocates with the needle 30. The outflow hole 52 that penetrates the cylindrical wall of the movable core 50 forms a fuel passage that communicates the inside and outside of the cylinder of the movable core 50. The fixed core 54 is made of a magnetic material and has a substantially cylindrical shape. The fixed core 54 is inserted into the cylindrical member 40 and is fixed to the cylindrical member 40 by welding. The fixed core 54 is installed on the side opposite to the injection hole with respect to the movable core 50 and faces the movable core 50. The adjusting pipe 56 is press-fitted into the inner periphery of the fixed core 54 and forms a fuel passage therein. The compression spring 58 is locked to the adjusting pipe 56 at one end and is locked to the movable core 50 at the other end. By adjusting the press-fitting amount of the adjusting pipe 56, the load of the compression spring 58 that biases the movable core 50 is changed. The movable core 50 and the needle 30 are biased toward the valve seat 14 by the biasing force of the compression spring 58. The coil 60 is wound around a spool 62. The terminal 65 is insert-molded in the connector 64 and is electrically connected to the coil 60. When the coil 60 is energized, a magnetic attractive force acts between the movable core 50 and the fixed core 54, and the movable core 50 is attracted toward the fixed core 54 against the urging force of the compression spring 58.

  Here, the valve body 12 and the needle 30 constitute a valve portion B. Of the valve part B, the valve seat 14 and the contact part 31 constitute a seat part. The nozzle hole 21 constitutes a fuel spray forming means for atomizing the fuel and forming a spray. When the fuel injection valve 2 having the above-described configuration supplies current from the connector 64 to the coil 60 and the needle 30 starts to lift, the fuel flowing into the fuel passage is injected from the valve portion B into the cylinder of the engine 100. The fuel injection valve 2 has a compression spring 58 that urges the needle 30 in the seating direction. When the supply of current to the coil 60 is stopped, the valve portion B is closed and the injection ends.

As shown in FIGS. 1 and 2A, the lift correction member 71 has a function of correcting a lift change due to a difference in thermal expansion between an internal operation member such as the needle 30 and an outer member such as the valve body 12, and is movable. The maximum movement amount of the core 50, that is, the lift amount L of the needle 30 is defined. For more information, includes a lift correction member 71, as shown in FIG. 2 (a), the lift stopper 72 for restricting the lift amount L of the needle 30, a spring 73 as a biasing member for urging the lift stopper 72 ing. The lift correction member 71 is formed in a substantially cylindrical shape as shown in FIGS. 1 and 2, and the shaft end portion 71b on the counter-injection hole 21 side of the lift correction member 71 has a lift stopper 72 as shown in FIG. The shaft end 71a on the nozzle hole 21 side is disposed so as to always abut against the upper end of the valve body 12 as shown in FIG. As a result, the internal members such as the lift correction member 71 and the needle 30 and the movable core 50 are immersed in the fuel in the internal fuel passage, so that the influence of the heat change on the engine 100 side is affected by the outer member such as the valve body 12. It is hard to receive than. Therefore, when the valve body 12 receives heat due to a heat change or the like on the engine 100 side, a temperature difference is generated between the outer member on the valve body 12 side and the internal working member such as the needle 30, thereby causing a thermal expansion difference. However, the valve body 12 side and the needle 30 are combined by a combination of the lift correction member 71 and the internal operation member on the needle 30 side (specifically, the needle 30 and the movable core 50) that are relatively less susceptible to the influence of the heat change on the engine 100 side. It is possible to reduce or prevent a lift change due to a difference in thermal expansion from the side.

  Here, the lift correction member 71 constitutes a reference member for correcting a difference in thermal expansion between the inner working member on the needle 30 side and the outer member on the valve body side. The lift correction member 71 is preferably made of a material such as a ceramic having a relatively small thermal expansion coefficient. In a heat change on the engine 100 side, for example, a heat change from a low temperature state to a high temperature state, the difference in thermal expansion between the inner working member on the needle 30 side and the outer member on the valve body 12 side also depends on the material of the lift correction member 71 itself. It is possible to suppress the influence.

  As shown in FIG. 2A, the lift stopper 72 is urged against the lift correction member 71 by a spring 73. Since the lift stopper 72 and the lift correction member 71 are biased toward the upper end portion of the valve body 12 by the biasing force of the spring 73, the shaft end portion 71 a on the injection hole 21 side of the lift correction member 71 is connected to the valve body 12. It is always in contact with the upper end.

  In the present embodiment, the biasing force of the spring 73 is such that the lift stopper 72 and the lift correction member 71 can maintain a contact state as shown in FIG. Specifically, when the movable core 50 is magnetically attracted by the fixed core 54 and the movable core 50 collides with and is locked with the lift stopper, the lift stopper 72 and the lift correction member 71 can be kept in contact with each other without being separated. Have a load of.

  Furthermore, as long as the spring 73 has the above urging force, the spring 73 may be a disc spring shape as shown in FIG. 1 and FIG. Any spring shape may be used.

  Further, in the present embodiment, the lift stopper 72 is disposed between the movable core 50 and the fixed core 54. Thereby, the maximum movement amount of the movable core 50, that is, the lift amount of the needle 30 can be defined by the axial position of the lift stopper 72. Therefore, even when the ambient temperature is affected, the lift correction member 71 lifts the needle 30 at the position of the lift stopper 72 in which the lift change due to the thermal expansion difference between the valve body 12 side and the needle 30 side is corrected. The change of quantity can be prevented.

  Furthermore, in this embodiment, the movable core 50 is formed so that the lift correction member 71 can be inserted as shown in FIG. Specifically, the movable core 50 has an insertion hole 51 having an inner periphery larger than the outer periphery along the outer periphery of the substantially cylindrical lift correction member 71. Thus, a predetermined radial gap can be provided between the movable core 50 (more specifically, the insertion hole 51) on which the magnetic force acts and the lift correction member 71, so that the gap between the movable core 50 and the lift correction member 71 can be provided. Thus, the influence of the magnetic flux acting in the radial direction can be reduced or prevented, that is, the influence of the so-called side force can be reduced or prevented. Therefore, the movable core 50, that is, the needle can be lifted smoothly.

  Furthermore, since the movable core 50 is formed so that the lift correction member 71 can be inserted therethrough, the position of the lift correction member 71 in the axial direction (specifically, the shaft end portion 71b on the anti-injection hole 21 side) due to the thermal expansion of the valve body 12. ) Changes, the movable core 50 can move in the axial direction along the lift correction member 71 to the shaft end portion 71b on the counter injection hole 21 side, and the maximum movement amount of the movable core 50 by the lift correction member 71 That is, the lift amount of the needle 30 can be regulated.

  Furthermore, when the lift correction member 71 is composed of a plurality of (four in this embodiment) substantially cylindrical members as in this embodiment, four lift correction members 71 are provided in the middle of the substantially cylindrical member in the axial direction. An annular member 71j that holds the substantially cylindrical member may be provided. The annular member 71j is formed to be movable in the axial direction on the inner periphery of the valve housing 16 and the inner periphery 40a of the tubular member 40.

  Here, the lift correction member 71, the lift stopper 72, and the spring 73 correct the change in lift due to the difference in thermal expansion between the internal working member such as the needle 30 and the outer member such as the valve body 12, and the lift amount L of the needle 30 is corrected. The lift correction mechanism 70 is configured to maintain the value at a predetermined value.

  Next, the operation of the fuel injection valve of the present embodiment having the above-described configuration will be described. When the vehicle engine key is set to the IG position and an ignition switch (not shown) is turned on, the fuel pump is driven, and the fuel is sucked into the fuel tank by the fuel pump. The sucked fuel is regulated by a pressure regulator, and a predetermined low pressure fuel is supplied to the high pressure pump. The predetermined low pressure fuel is pressurized by the high pressure pump, and the pressurized fuel is supplied to the fuel distribution pipe. The fuel supplied to the fuel distribution pipe is regulated to a predetermined high pressure fuel by a pressure regulator and supplied to the fuel injection valve 2 from each distribution port in the fuel distribution pipe.

  At the time of fuel injection of the fuel injection valve 2, when a current is supplied to the coil 60 of the fuel injection valve 2 and the needle 30 starts to lift, the valve portion B is opened and fuel injection is started. The fuel is injected from the injection hole 21, atomized, and supplied to the combustion chamber 106. On the other hand, when the fuel injection is stopped, the current supply to the coil 60 is stopped, and the lift of the needle 30 is reduced by the spring 58. When the needle 30 is seated on the valve seat 14, the injection is finished. By adjusting the energization period to the coil 60, the fuel injected from the fuel injection valve 2, that is, the fuel injection amount is adjusted.

  Here, the fuel injection valve 2 of the present embodiment is arranged so that the tip end side of the valve body 12 and the like is directed to the combustion chamber 106 as in the fuel injection valve 902 of the comparative example shown in FIG. . In the fuel injection valve 902 of the comparative example, as shown in FIG. 5, a part of the valve body 12 and the valve housing 16 is accommodated in the stepped communication hole of the cylinder head 102 via the gasket 103 as a seal member. The tip of the valve body 12 and the valve housing 16 on the lower side in the figure from the gasket 103 may be exposed to the flame and combustion gas generated in the combustion chamber 106. The valve body 12 and the valve housing 16 may be heated to about 100 to 150 ° C. The cylinder head 102 is cooled and kept at about 80 ° C. (in some cases 60 to 100 ° C.) by the effect of a water cooling type cooling device such as a water jacket on the engine 100 side. In a wide range of operating states such as a cold state such as a driving state where the vehicle stops idling from traveling in a high load state, there is a possibility of changing from outside air temperature to 100 ° C.

  Therefore, like the fuel injection valve 902 of the comparative example, the fixed core 954 of the electromagnetic drive unit is fixed to the valve housing 916, and the maximum movement amount of the movable core 950 due to the air gap L between the fixed core 954 and the movable core 950. In other words, in the structure that determines the lift amount of the needle 930, if a heat change on the engine side, for example, a heat change from a low temperature state to a high temperature state due to combustion occurs, the lift amount may change in an increasing direction and the fuel injection amount may change. It was. Specifically, the valve valve 12 and the valve housing 16 are thermally expanded due to a high temperature and extend in the arrow direction in FIG. When the valve body 12 side extends downward, the valve body 12 itself (specifically, the valve seat 14) also moves downward, so that the valve seat, that is, the initial lift position of the needle 30 also moves downward. As a result, since the air gap, that is, the lift amount L increases, the fuel injection amount may change (specifically, increase) by the increase in the lift amount.

  On the other hand, in the fuel injection valve 2 of the present embodiment, the lift correction member 71 in contact with the upper end portion of the valve body 12 also moves downward, so that the lift stopper 72 is lift-corrected by the biasing force of the spring 73. It is possible to follow the change in the axial position of the member 71 (specifically, the shaft end portion 71b on the anti-injection hole 21 side). Therefore, even when the temperature of the engine 100 side W is affected by the ambient temperature due to the heat received on the valve body 12 side, the lift amount of the needle 30 can be prevented from changing.

  Next, operations and effects of the present embodiment will be described. (1) In the present embodiment, a lift correction member 71 is provided. The lift correction member 71 includes an internal operation member such as the needle 30 and an outer member such as the valve body 12. It has a function of correcting a lift change due to a difference in thermal expansion, and defines a maximum movement amount of the movable core 50, that is, a lift amount L of the needle 30. Accordingly, even if there is a difference in thermal expansion between the needle 30 side inside and the valve body 12 that houses the needle 30 side due to the influence on the engine 100 side such as combustion in the combustion chamber 106, the lift correction member 71 prevents the lift amount from changing. In other words, the lift change due to the difference in thermal expansion between the valve body 12 side and the needle 30 side can be mitigated or prevented, and the lift correction member 71 is affected by the ambient temperature due to the heat received by the fuel injection valve 2. Also, the lift amount of the needle 30 is caused to act at a predetermined value. Therefore, even when the valve body 12 and the like are affected by the ambient temperature due to heat reception, the change in the lift amount of the needle 30 can be prevented.

(2) The present embodiment is provided with a lift correction member 71, the lift stopper 72 for restricting the lift amount L of the needle 30, a spring 73 for urging the lift stopper 72 to lift correction member 71 side . Thus, the axial position of the lift correction member 71 (specifically, the shaft end portion 71b on the anti-injection hole 21 side) is changed so as to reduce or prevent the difference in thermal expansion between the valve body 12 side and the needle 30 side. The lift stopper 72 can be made to follow the change in the axial position of the lift correction member 71 by the biasing force of the spring 73. Therefore, even if it is a case where it receives to the influence of ambient temperature, it can prevent that the lift amount of the needle 30 changes.

  More specifically, the shaft end portion 71b on the counter injection hole 21 side faces the lift stopper 72 and the shaft end portion 71a on the injection hole 21 side is the upper end of the valve body 12 among the shaft end portions of the lift correction member 71. It arrange | positions so that it may always contact | abut. As a result, the internal members such as the lift correction member 71 and the needle 30 and the movable core 50 are immersed in the fuel in the internal fuel passage, so that the influence of the heat change on the engine 100 side is affected by the outer member such as the valve body 12. It is hard to receive than. Therefore, when the valve body 12 receives heat due to a heat change or the like on the engine 100 side, a temperature difference is generated between the outer member on the valve body 12 side and the internal working member such as the needle 30, thereby causing a thermal expansion difference. However, the combination of the lift correction member 71 and the needle 30 side, which is relatively insensitive to the heat change on the engine 100 side, can alleviate or prevent the lift change due to the difference in thermal expansion between the valve body 12 side and the needle 30 side. it can.

  (3) Furthermore, in this embodiment, the movable core 50 is formed so that the lift correction member 71 can be inserted. As a result, a predetermined radial gap can be provided between the movable core 50 on which the magnetic force acts and the lift correction member 71, so that the side acting in the radial direction between the movable core 50 and the lift correction member 71 can be provided. The influence of the force can be reduced or prevented. Therefore, the movable core 50, that is, the needle can be lifted smoothly.

  Further, since the movable core 50 is formed so that the lift correction member 71 can be inserted, the movable core 50 can move in the axial direction along the lift correction member 71 to the shaft end portion 71b on the side of the anti-injection hole 21. The maximum movement amount of the movable core 50 by the member 71, that is, the lift amount of the needle 30 can be regulated.

  (4) Furthermore, in this embodiment, the lift stopper 72 is disposed between the movable core 50 and the fixed core 54. Thereby, the maximum movement amount of the movable core 50, that is, the lift amount of the needle 30 can be defined by the axial position of the lift stopper 72. Therefore, even when the temperature is affected by the ambient temperature, the lift amount of the needle 30 changes at the position of the lift stopper 72 where the difference in thermal expansion between the valve body 12 side and the needle 30 side is corrected by the lift correction member 71. Can be prevented.

  (5) In general, the valve seat 14 of the valve body is required to have relatively strong wear resistance because the needle 30 is repeatedly seated and separated for each fuel injection. On the other hand, in the present embodiment, a portion of the valve body on the valve seat 14 side, that is, the valve body 12 is connected to the electromagnetic drive unit S (specifically, the cylindrical member 40) with a specific material having relatively high wear resistance. For example, an inexpensive material other than the specific material can be used for the valve housing 16 on the side to be operated.

  Further, since the upper end portion of the valve body 12 is disposed inside the valve housing 16, the shaft end portion 71 a on the injection hole 21 side of the lift correction member 71 is brought into contact with the upper end portion of the valve body 12. It is done. Thereby, the axial position of the lift correction member 71 can be changed so as to reduce or prevent the difference in thermal expansion between the valve body 12 side and the needle 30 side.

  (6) The lift correction member 71 is preferably made of a material such as ceramic having a relatively small coefficient of thermal expansion. In a heat change on the engine 100 side, for example, a heat change from a low temperature state to a high temperature state, the difference in thermal expansion between the inner working member on the needle 30 side and the outer member on the valve body 12 side also depends on the material of the lift correction member 71 itself. It is possible to suppress the influence.

The lift correction member 71 constitutes a reference member for correcting a lift change due to a difference in thermal expansion between the inner working member on the needle 30 side and the outer member on the valve body side .

(Second Embodiment)
Hereinafter, other embodiments to which the present invention is applied will be described. In the following embodiments, the same or equivalent components as those in the first embodiment are denoted by the same reference numerals, and description thereof will not be repeated.

  In the second embodiment, in the shape of the movable core 50 that allows the lift correction member 71 described in the first embodiment to be inserted, instead of the insertion hole 51, as shown in FIG. The groove 151 is formed. FIG. 4 is a schematic cross-sectional view showing the positional relationship between the lift correction member and the movable core according to this embodiment.

  As shown in FIG. 4, a groove portion 151 having a groove width larger than the outer periphery of the lift correction member 71 is formed on the outer peripheral portion of the movable core 50.

  Even if it is such a structure, the effect similar to 1st Embodiment can be acquired.

(Other embodiments)
In the present embodiment described above, the valve body according to claim 1 is a separate member for the valve seat 14 side (specifically, the valve body 12) and the valve housing 16 connected to the electromagnetic drive unit S. However, the present invention is not limited to being integrally formed and may be integrally formed.

It is sectional drawing which shows schematic structure of the fuel injection valve of the 1st Embodiment of this invention. FIG. 2A is a partially enlarged view of FIG. 1, FIG. 2A is a partial cross-sectional view showing the periphery of the movable core and the fixed core, and FIG. 2B is a partial cross-sectional view showing the periphery of the valve member and the valve body. It is typical sectional drawing which shows the arrangement | positioning relationship of the lift correction member and movable core seen from III-III of Fig.2 (a). It is typical sectional drawing which shows the arrangement | positioning relationship between the lift correction member and movable core concerning 2nd Embodiment. It is typical sectional drawing which shows the mounting state to the internal combustion engine of the fuel injection valve of a comparative example.

Explanation of symbols

2 Fuel Injection Valve 12 Valve Body 14 Valve Seat 16 Valve Housing (Housing)
21 injection hole 30 needle (valve member)
40 cylindrical member 50 movable core 54 fixed core 60 coil 71 lift correction member 71a, 71b shaft end 72 lift stopper 73 spring (biasing member)
100 engine (internal combustion engine)
102 Cylinder head 106 Combustion chamber B Valve part S Electromagnetic drive part

Claims (4)

Used in an internal combustion engine having a combustion chamber in a cylinder and injecting fuel to the combustion chamber;
A valve body having a valve seat;
A valve member housed in the valve body so as to be axially movable, and seated and separated from the valve seat;
An electromagnetic drive unit fixed to the valve body side and driving the valve member by magnetic action;
A fuel injection valve that determines a fuel injection amount to be supplied to the combustion chamber based on a lift amount of the valve member that is separated from the valve seat and a valve opening period that is separated from the valve seat;
A lift correction mechanism for correcting a difference in thermal expansion between the valve body side and the valve member side and defining a lift amount of the valve member;
The lift correction mechanism is formed of a lift stopper that regulates the lift amount of the valve member and a material having a smaller thermal expansion coefficient than the valve body, one end abutting the lift stopper, and the other end of the valve body The lift correction member that contacts the lift correction member, and the lift stopper and the lift correction member are biased toward the lift correction member side, thereby maintaining the respective contact states of the lift stopper, the lift correction member, and the lift correction member and the valve body. An urging member, and correcting the difference in thermal expansion between the valve body side and the valve member side by causing the lift stopper to follow the valve body via the lift correction member. A fuel injection valve that defines a lift amount. The electromagnetic drive unit includes a movable core that cooperates with the valve member, and a fixed core that magnetically attracts the movable core,
The fuel injection valve according to claim 1, wherein the movable core is formed so that the lift correction member can be inserted therethrough.   The fuel injection valve according to claim 2, wherein the lift stopper is disposed between the movable core and the fixed core. The valve body has a housing connected to the electromagnetic drive unit,
The fuel injection valve according to any one of claims 1 to 3, wherein an upper end portion of the valve body is disposed inside the housing .

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