JP3823819B2 - Fuel injection pump - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fuel injection pump that supplies high-pressure fuel to an internal combustion engine (hereinafter, the internal combustion engine is referred to as an “engine”).
[0002]
[Prior art]
2. Description of the Related Art Conventionally, for example, a fuel injection pump for a diesel engine is known in which fuel in a pressurizing chamber is pumped to a fuel injection device such as an injector by reciprocal movement of a plunger accompanying rotation of a drive shaft. As an example of the fuel injection pump as described above, there is one having a roller that comes into contact with a cam. In such a fuel injection pump, when the cam is rotated, the roller rotates along the profile surface of the cam and is reciprocated in the axial direction of the plunger. A tappet is disposed between the plunger and the roller, and the plunger is accommodated on the opposite side of the tappet. Therefore, the tappet is also reciprocated together with the reciprocating roller, and the plunger accommodated in the tappet is also reciprocated in the axial direction. By reciprocating the plunger, the fuel is sucked into the pressurizing chamber and pressurized. The roller rotates around a roller pin formed integrally, and the end of the roller pin is rotatably supported by a support portion of the tappet.
[0003]
[Problems to be solved by the invention]
Since the roller pin is rotatably supported by the support portion, the roller pin and the tappet slide on the support portion. For this reason, it is necessary to lubricate the sliding portion. In the case of a conventional fuel injection pump, the tappet is formed with a plunger accommodating portion that accommodates a plunger and a roller accommodating portion that accommodates a roller. Therefore, a communication path that communicates the plunger accommodating part and the roller accommodating part is formed, and lubricating oil is supplied to the roller accommodating part via the communication path.
[0004]
However, the lubricating oil supplied via the communication path is used for lubrication between the roller and the cam. For this reason, it is difficult to supply sufficient lubricating oil to the sliding portion formed between the roller pin and the tappet even if lubricating oil is supplied to the roller accommodating portion. Therefore, the oil film is not sufficiently formed in the sliding portion formed between the roller pin and the tappet, and there is a possibility that seizure occurs between the roller pin and the tappet.
[0005]
Therefore, an object of the present invention is to provide a fuel injection pump that prevents seizure between a roller pin and a tappet.
[0006]
[Means for Solving the Problems]
According to the fuel injection pump of the first or second aspect of the present invention, the recess is formed in the outer peripheral portion of the tappet. As for this hollow part, one edge part is connected with the plunger accommodating part, and the other edge part is connected with the support part via the communicating path. Therefore, the lubricating oil in the plunger accommodating portion flows into the recess and is supplied to the support portion. Thereby, lubricating oil is supplied between the sliding roller pin and the support part, and formation of the oil film of a sliding part is accelerated | stimulated. Therefore, seizure of the sliding portion formed between the roller pin and the tappet can be prevented.
[0007]
Further, the cross-sectional area of the hollow portion decreases in the direction of the drive shaft. When the tappet moves in the direction of the pressurizing chamber, a force that flows in the direction of the anti-pressurizing chamber, that is, the direction of the drive shaft, acts on the lubricating oil that has flowed into the recess due to the viscosity of the lubricating oil itself. Therefore, by reducing the cross-sectional area of the recess in the drive shaft direction, the pressure of the lubricating oil increases with the flow in the drive shaft direction. Therefore, pressurized lubricating oil flows into the communication path, and supply of the lubricating oil to the support portion can be promoted.
[0008]
According to the fuel injection pump of the third aspect of the present invention, the communication path is formed in the tangential direction of the roller pin. As the roller pin rotates, the pressure on the rear side in the rotation direction of the roller pin decreases. Therefore, by forming the communication path toward the tangential direction of the roller pin, the lubricating oil is sucked from the communication path between the roller pin and the support portion. Therefore, the flow rate of the lubricating oil flowing into the sliding portion increases, and seizure of the sliding portion can be prevented.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a plurality of examples showing embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
A fuel injection pump according to a first embodiment of the present invention is shown in FIG. The fuel injection pump 1 according to the first embodiment of the present invention is applied to a high-pressure pump used in a common rail fuel injection system of a diesel engine.
[0010]
The fuel injection pump pressurizes fuel sucked from a fuel tank (not shown) via a low pressure pump (not shown) and supplies the pressurized fuel to a common rail (not shown).
As shown in FIG. 2, the fuel injection pump 1 includes a pump housing 10, and a cam chamber 11 is formed at one end of the pump housing 10. The cam chamber 11 houses a drive shaft 12 that is driven and rotated by the engine. A cam 13 is formed integrally with the drive shaft 12 on the drive shaft 12.
[0011]
A cylinder body 20 is attached to the pump housing 10 on the side opposite to the cam chamber, and a cylinder 21 is formed on the cylinder body 20. The pump housing 10 and the cylinder body 20 constitute the housing described in the claims. A plunger 30 is supported in the cylinder 21 so as to be slidable in the axial direction. A tappet chamber 14 is formed between the inner peripheral side of the pump housing 10 and the cylinder body 20, and a tappet 40 is accommodated in the tappet chamber 14 so as to be reciprocally movable.
[0012]
The plunger 30 is formed in a cylindrical shape. A pressurizing chamber 31 is formed from the upper end surface of the plunger 30 and the inner peripheral surface of the cylinder 21. The cylinder body 20 is formed with a fuel reservoir 23 through which fuel is supplied from a low-pressure pump (not shown) via an introduction pipe 22. The fuel reservoir 23 communicates with a fuel supply path 61 in the control valve 60. The control valve 60 includes an electromagnetic drive unit 62 and a valve member 63 driven by the electromagnetic drive unit 62. The valve member 63 can be seated on the valve seat portion 64. That is, the passage communicating with the pressurizing chamber 31 is opened and closed by controlling the electromagnetic drive unit 62.
[0013]
In the cylinder body 20, an electromagnetic drive unit 62 of a control valve 60 is screwed at a position facing the upper end surface of the plunger 30. The electromagnetic drive unit 62 communicates or blocks the fuel supply path 61 and the pressurizing chamber 31 by driving the valve member 63. By controlling the energization timing to the electromagnetic drive unit 62, the flow rate of fuel discharged from the fuel injection pump 1 to a common rail (not shown) is adjusted.
[0014]
A discharge valve 24 is installed in the cylinder body 20, and the discharge valve 24 communicates with the pressurizing chamber 31 through the discharge hole 25. The pressurized fuel in the pressurizing chamber 31 opens the valve member 241 of the discharge valve 24 against the urging force of the spring 242 and the pressure of the fuel in the discharge hole 26, and the pressurized high-pressure fuel is It is pumped from a discharge hole 26 into a common rail (not shown).
[0015]
A plunger head 32 is formed at the end of the plunger 30 on the side opposite to the pressure chamber. The plunger head 32 is connected to the lower seat 33. A spring 34 is in contact with the lower seat 33, and the plunger 30 is pressed against the tappet 40 by the urging force of the spring 34 through the lower seat 33. The other end of the spring 34 is in contact with the upper sheet 35, and movement of the spring 34 toward the pressurizing chamber 31 is restricted.
[0016]
The roller unit 50 includes a roller 51 and a roller pin 52. The roller 51 is in contact with the cam 13 and is rotatable about a roller pin 52 that is integrally formed. As shown in FIG. 1, a bush 53 is disposed between the roller 51 and the roller pin 52. The roller 51 is formed in an annular shape, and a roller pin 52 is inserted through a bush 53 on the inner peripheral side. The roller pin 52 is formed in a solid cylindrical shape. The roller part 50 is installed on the drive shaft 12 side of the tappet 40, and the roller 51 is rotatably accommodated in a roller accommodating part 41 formed on the tappet 40 as shown in FIG. The roller pin 52 is supported by the support portion 42 of the tappet 40. The roller pin 52 is rotatably supported by the support portion 42 of the tappet, and the outer wall 52a of the roller pin 52 and the inner wall 42a of the support portion 42 form a sliding portion.
[0017]
The tappet 40 is formed in a substantially cylindrical shape, and has a partition portion 43 near the central portion in the axial direction. The partition part 43 partitions the inner peripheral side of the tappet 40 into two spaces. Of the spaces partitioned by the partition portion 43, one space is a plunger housing portion 44 in which the plunger 30 is housed, and the other space is a roller housing portion 41 in which the roller 51 is housed. Support portions 42 for supporting the roller pins 52 are provided at both axial ends of the roller 51 of the roller accommodating portion 41. As shown in FIG. 2, the plunger 30 is accommodated in the plunger accommodating portion 44, and the plunger head 32 is in contact with the end surface of the partition portion 43 on the pressurizing chamber 31 side.
[0018]
As shown in FIG. 3, the partition portion 43 is formed with a through hole 45 that allows the plunger housing portion 44 and the roller housing portion 41 to communicate with each other. A part of the lubricating oil filling the tappet chamber 14 shown in FIG. 2 is supplied from the plunger housing part 44 to the roller housing part 41 via the through hole 45. Lubricating oil supplied to the roller accommodating portion 41 provides lubrication between the roller 51 and the cam 13 and between both end portions in the axial direction of the roller 51 and the inner wall of the roller accommodating portion 41.
[0019]
As shown in FIG. 2, the tappet 40 can reciprocate in the tappet chamber 14 formed inside the pump housing 10, and the outer wall of the tappet 40 slides with the inner wall of the pump housing 10. As shown in FIG. 3, a recess 46 is formed on the outer periphery of the tappet 40. As shown in FIG. 4, the recess 46 is formed in a substantially bell shape when viewed from the front, and the circumferential length of the tappet 40 is reduced from the upper end 46 a to the lower end 46 b on the pressurizing chamber 31 side. As shown in FIG. 3, the bottom 461 of the recess 46 is formed in an arcuate cross section along the axis of the tappet 40, and the recess 46 is shallow from the upper end 46a to the lower end 46b. Therefore, as shown in FIGS. 5A and 5B, the cross-sectional area of the recess 46 is larger toward the pressurizing chamber 31 and is reduced toward the drive shaft 12. The end of the recess 46 on the drive shaft 12 side, that is, the lower end 46 b communicates with the communication path 47.
[0020]
As shown in FIG. 3, the end on the pressurizing chamber 31 side of the recess 46, that is, the upper end 46 a communicates with the plunger accommodating portion 44. On the other hand, the lower end 46 b of the recess 46 communicates with the communication path 47. The communication passage 47 has one end communicating with the recess 46 and the other end communicating with the support 42. As shown in FIG. 4, the communication passage 47 is formed from the lower end 46 b of the recess 46 toward the central axis of the roller pin 52. On the other hand, the communication passage 47 is formed at a predetermined angle with the central axis of the tappet 40 in a cross section along the axis of the tappet 40 and the axis of the roller pin 52 as shown in FIG. That is, the communication passage 47 is formed to be inclined from the outer peripheral side of the tappet 40 to the inner peripheral side.
[0021]
When the tappet 40 ascends in the tappet chamber 14 toward the pressurizing chamber 31, the lubricating oil filled in the tappet chamber 14 flows from the plunger accommodating portion 44 of the tappet 40 into the recess 46. Since the tappet 40 and the pump housing 10 are slid, when the tappet 40 rises in the direction of the pressurizing chamber 31, the lubricating oil that has flowed into the recessed portion 46 has the tappet 40 due to the viscosity and inertia of the lubricating oil itself. A force is applied in the direction opposite to the moving direction, that is, in the direction of the drive shaft 12, and a force that flows in the direction of the lower end portion 46 b of the recess 46 acts. Since the cross-sectional area of the recess 46 is reduced in the direction toward the drive shaft 12, the pressure of the lubricating oil in the recess 46 increases as it flows in the direction of the drive shaft 12. Therefore, the lubricating oil in the recess 46 flows into the communication passage 47 in a pressurized state as the tappet 40 rises. As a result, the lubricating oil that has flowed into the recess 46 from the plunger housing 44 is supplied to the support 42 via the communication path 47.
[0022]
Next, the operation of the fuel injection pump 1 of this embodiment will be described.
As the drive shaft 12 rotates, the cam 13 integrated with the drive shaft 12 also rotates. Therefore, the roller 51 in contact with the cam 13 reciprocates in the vertical direction in FIG. 2 along the profile surface of the cam 13 and rotates around the roller pin 52. As the roller 51 reciprocates in the vertical direction in FIG. 2, the tappet 40 supporting the roller 51 is reciprocated in the tappet chamber 14 in the vertical direction in FIG. As a result, the plunger 30 in contact with the tappet 40 is also reciprocated in the vertical direction in FIG.
[0023]
When the control valve 60 is opened, that is, when the valve member 63 is separated from the valve seat 64 when the plunger 30 descends in the cylinder 21, the fuel in the introduction pipe 22 and the fuel reservoir 23 is supplied to the fuel supply path 27 and the fuel supply path 61. Through the pressure chamber 31. When the control valve 60 is closed, that is, the valve member 63 is seated on the valve seat 64, the fuel sucked into the pressurizing chamber 31 can be pressurized. When no current is applied to the electromagnetic drive unit 62, the valve member 63 is separated from the valve seat 64, and the fuel in the pressurizing chamber 31 is supplied from the pressurizing chamber 31 as the plunger 30 is raised. It overflows into the fuel reservoir 23 via the path 61 and the fuel supply path 27. Therefore, the fuel sucked into the pressurizing chamber 31 is not pressurized.
[0024]
When the fuel is overflowing from the pressurizing chamber 31, when a control pulse is sent to the electromagnetic drive unit 62, the valve member 63 is seated on the valve seat portion 64, and the pressurizing chamber 31 is closed. As a result, pressurization of the fuel in the pressurizing chamber 31 is started as the plunger 30 is raised. When the fuel in the pressurizing chamber 31 is pressurized and the pressure of the fuel becomes larger than the urging force of the spring 242 of the discharge valve 24 and the pressure of the fuel in the discharge hole 26, the discharge valve 24 is opened and pressurized. The fuel is discharged through a discharge hole 26 to a common rail (not shown).
[0025]
As described above, according to the fuel injection pump 1 according to the first embodiment of the present invention, the lubricating oil that has flowed into the recessed portion 46 that communicates with the plunger housing portion 44 is supplied to the support portion 42 via the communication passage 47. The Thereby, since the lubricating oil is supplied from the communication path 47 to the sliding portion formed between the support portion 42 and the roller pin 52, formation of an oil film in the sliding portion is promoted. Therefore, seizure of the sliding portion formed between the support portion 42 of the tappet 40 and the roller pin 52 of the roller portion 50 can be prevented.
[0026]
Further, the cross-sectional area of the recess 46 decreases in the direction of the drive shaft 12. Therefore, as the tappet 40 rises, the lubricating oil in the recessed portion 46 is pressurized, and the lubricating oil pressurized in the recessed portion 46 flows into the communication path 47. Therefore, the flow of the lubricating oil from the recessed portion 46 to the support portion 42 can be promoted, and the lubricating oil can be reliably supplied to the sliding portion.
[0027]
(Second embodiment)
The tappet of the fuel injection pump according to the 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.
The tappet 40 of the fuel injection pump according to the second embodiment is different from the first embodiment in the formation position of the communication passage 48 as shown in FIG.
[0028]
Similarly to the first embodiment, the communication path 48 communicates the recessed portion 46 and the support portion 42 and is formed to be inclined from the outer peripheral side of the tappet 40 to the inner peripheral side. However, in the second embodiment, the communication passage 48 is formed at a predetermined angle with respect to the axis of the tappet 40 in the tangential direction of the roller pin 52. That is, the axis of the tappet 40 and the axis of the communication path 48 are in a twisted relationship. Further, the communication path 48 is open to the support portion 42 so as to be located on the rear side in the rotation direction of the roller pin 52. That is, when the roller pin 52 rotates in the arrow R direction, the end portion 48 a on the support portion 42 side of the communication path 48 is located on the rear side in the rotation direction of the roller pin 52.
[0029]
Due to the rotation of the roller pin 52, the lubricating oil between the inner wall 42 a of the support portion 42 and the roller pin 52 is pressurized on the front side in the rotation direction of the roller pin 52 and depressurized on the rear side in the rotation direction. Therefore, the pressure of the lubricating oil decreases on the rear side in the rotation direction of the roller pin 52. As a result, the lubricating oil in the communication path 48 is sucked to the rear side in the rotation direction of the roller pin 52 whose pressure has decreased, and is supplied between the roller pin 52 and the support portion 42.
[0030]
In the second embodiment, the lubricating oil in the communication passage 48 can be supplied between the support portion 42 and the roller pin 52 using the suction effect of the lubricating oil by the rotation of the roller pin 52. Therefore, the lubricating oil in the communication passage 48 can smoothly flow into the sliding portion between the support portion 42 and the roller pin 52 to form an oil film. Therefore, seizure of the sliding portion formed between the support portion 42 and the roller pin 52 can be reliably prevented.
[0031]
As described above, in the embodiments of the present invention, the example in which the fuel injection pump of the present invention is applied to the high-pressure pump of the common rail fuel injection system has been described. However, the present invention is not limited to a common rail fuel injection system, but can be applied to a high pressure pump that pressurizes fuel in another fuel injection system.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view taken along line II in FIG. 2, and is an enlarged view of the vicinity of a tappet.
FIG. 2 is a schematic cross-sectional view showing a fuel injection pump according to a first embodiment of the present invention.
FIG. 3 is a sectional view showing a tappet and a roller member of the fuel injection pump according to the first embodiment of the present invention.
4 is an arrow view of the tappet viewed from the direction of arrow IV in FIG. 3;
5A is a schematic diagram showing a cross section of a dent portion cut along the line AA in FIG. 4, and FIG. 5B is a schematic diagram showing a cross section of the dent portion cut along a line BB in FIG. 4; FIG.
6 is a schematic view showing a tappet according to a second embodiment of the present invention, viewed from the same direction as the arrow IV in FIG. 3. FIG.
[Explanation of symbols]
1 Fuel Injection Pump 10 Pump Housing (Housing)
11 Cam chamber 12 Drive shaft 13 Cam 20 Cylinder body (housing)
21 Cylinder 30 Plunger 31 Pressurizing chamber 40 Tappet 41 Roller accommodating portion 42 Supporting portion 43 Partitioning portion 44 Plunger accommodating portion 46 Recessed portion 47, 48 Communication path 50 Roller portion 51 Roller 52 Roller pin

Claims (3)

A plunger for pressurizing the fuel sucked into the pressurizing chamber;
A housing having a cam chamber at one end, and a cylinder that supports the plunger in a reciprocating manner at the other end and forms the pressure chamber together with the plunger;
A cam housed in the cam chamber and rotating together with the drive shaft;
A roller abutting on the cam; and a roller pin on which the roller is integrally assembled. The roller moves along the profile surface of the cam so that the plunger reciprocates while rotating around the roller pin. A roller section that moves in the moving direction;
Plunger accommodating portion for accommodating the plunger, a support portion for rotatably supporting the roller pin, a roller accommodating portion for rotatably accommodating the roller, and an outer peripheral portion communicating with the plunger accommodating portion and going in the direction of the drive shaft And a tappet that transmits a reciprocating movement of the roller portion to the plunger. When,
A fuel injection pump comprising: The fuel injection pump according to claim 1, wherein the communication path is formed toward a central axis of the roller pin. 2. The fuel injection pump according to claim 1, wherein the communication path is formed in a tangential direction of the roller pin, and an end portion of the communication path on the support portion side is in communication with a rear side in the rotation direction of the roller pin. .

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