JP2003184699A - Fuel injection pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel injection pump for preventing backing between a roller pin and a tappet. <P>SOLUTION: A recess 46 is formed to a tappet 40. The recess 46 is communicated with a plunger receive chamber 44 for receiving a plunger 30 on one end, and communicated with a communication passage 47 on the other end. Lubricating oil filled in a tappet chamber 14 is supplied from the plunger receive chamber 44 via the recess 46 and the communication passage 47 to a supporting part 42 supporting both ends of a roller pin 52. The cross section area of the recess 46 is gradually reduced towards a driving shaft 12. Therefore, the lubrication oil in the recess 46 is pressurized, flows into the communication passage 47, and is supplied to the supporting part 42 by movement of the tappet 40. Thereby, the lubricating oil is surely supplied to the supporting part 42, so that the lubrication oil lubricates the space between the roller pin 52 and the supporting part 42. Thus, baking is prevented between the roller pin 52 and the support part 42. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an internal combustion engine (hereinafter,
An internal combustion engine is called an "engine." ) To a fuel injection pump for supplying high-pressure fuel.

[0002]

2. Description of the Related Art Conventionally, for example, as a fuel injection pump for a diesel engine, there is known a fuel injection pump that pumps fuel in a pressure chamber to a fuel injection device such as an injector by reciprocating movement of a plunger accompanying rotation of a drive shaft. As an example of the above fuel injection pump, there is one having a roller that abuts on a cam. In such a fuel injection pump, when the cam is rotated, the roller is rotated along the profile surface of the cam and is reciprocally driven in the axial direction of the plunger. A tappet is arranged between the plunger and the roller, and the plunger is accommodated on the side opposite to the roller of the tappet. Therefore, the tappet is reciprocally driven together with the reciprocally driven roller, and the plunger housed in the tappet is also reciprocally driven in the axial direction. When the plunger is reciprocally driven, fuel is sucked into the pressurizing chamber and pressurized. The roller rotates around a roller pin that is integrally formed, and the end portion of the roller pin is rotatably supported by the support portion of the tappet.

[0003]

Since the roller pin is rotatably supported by the supporting portion, the roller pin and the tappet slide on the supporting portion. Therefore, it is necessary to lubricate the sliding portion. In the case of the conventional fuel injection pump, the tappet has a plunger accommodating portion for accommodating the plunger and a roller accommodating portion for accommodating the roller. Therefore, a communication passage that connects the plunger storage portion and the roller storage portion is formed, and the lubricating oil is supplied to the roller storage portion via the communication passage.

However, the lubricating oil supplied through the communication passage is used for lubrication between the roller and the cam. Therefore, it is difficult to supply sufficient lubricating oil to the sliding portion formed between the roller pin and the tappet even if the 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 seizure may occur between the roller pin and the tappet.

Therefore, an object of the present invention is to provide a fuel injection pump which prevents seizure between the roller pin and the tappet.

[0006]

According to the fuel injection pump of the first or second aspect of the present invention, the tappet has a recess formed in the outer peripheral portion thereof. One end of the recess is in communication with the plunger accommodating portion, and the other end is in communication with the supporting portion via the communication passage. Therefore, the lubricating oil in the plunger accommodating portion flows into the hollow portion and is supplied to the support portion. As a result, the lubricating oil is supplied between the sliding roller pin and the supporting portion, and the formation of the oil film at the sliding portion is promoted.
Therefore, the seizure of the sliding portion formed between the roller pin and the tappet can be prevented.

Further, the cross-sectional area of the hollow portion decreases as it goes in the drive axis direction. When the tappet moves in the direction of the pressurizing chamber, a force that flows in the direction opposite to the pressurizing chamber, that is, the drive axis direction 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 recessed portion in the drive shaft direction, the pressure of the lubricating oil increases as the drive oil flows in the drive shaft direction. Therefore, the pressurized lubricating oil flows into the communication passage, and the supply of the lubricating oil to the support portion can be promoted.

According to the fuel injection pump of the third aspect of the present invention, the communication passage 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 passage in the tangential direction of the roller pin, the lubricating oil is sucked from the communication passage between the roller pin and the support portion. Therefore, the flow rate of the lubricating oil flowing into the sliding portion is increased, and seizure of the sliding portion can be prevented.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A plurality of embodiments showing the embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) FIG. 2 shows a fuel injection pump according to a first embodiment of the present invention. 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.

The fuel injection pump pressurizes the fuel sucked from a fuel tank (not shown) via a low pressure pump (not shown) and supplies it 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 on the drive shaft 12 integrally with the drive shaft 12.

A cylinder body 20 is mounted on the side opposite to the cam chamber of the pump housing 10, and a cylinder 21 is formed in 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 able to slide back and forth 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 reciprocally housed inside the tappet chamber 14.

The plunger 30 is formed in a cylindrical shape. A pressurizing chamber 31 is formed by the upper end surface of the plunger 30 and the inner peripheral surface of the cylinder 21. Cylinder body 2
At 0, a fuel reservoir 23 is formed in which fuel is supplied from a low-pressure pump (not shown) via an introduction pipe 22. The fuel pool 23 communicates with a fuel supply passage 61 in the control valve 60. The control valve 60 has 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, by controlling the electromagnetic drive unit 62, the passage communicating with the pressurizing chamber 31 is opened and closed.

The cylinder body 20 includes a plunger 30.
Of the control valve 60 at a position facing the upper end surface of the
Are fixed with screws. The electromagnetic drive unit 62 drives the valve member 63 to drive the fuel supply passage 61 and the pressurizing chamber 31.
Connect or disconnect with. The flow rate of the fuel discharged from the fuel injection pump 1 to the common rail (not shown) is adjusted by controlling the power supply timing to the electromagnetic drive unit 62.

A discharge valve 24 is installed in the cylinder body 20, and the discharge valve 24 is provided with a discharge hole 25 through which a pressure chamber 3 is provided.
It communicates with 1. The fuel pressurized in the pressurizing chamber 31 opens the valve member 241 of the discharge valve 24 against the biasing 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 pressure-fed from the discharge hole 26 into a common rail (not shown).

A plunger head 32 is formed at the end of the plunger 30 on the side opposite to the pressurizing chamber. The plunger head 32 is connected to the lower seat 33. The spring 34 is in contact with the lower seat 33, and the plunger 3
0 is pressed against the tappet 40 by the urging force of the spring 34 via the lower seat 33. Spring 3
The other end of No. 4 is in contact with the upper seat 35, and the movement of the spring 34 toward the pressurizing chamber 31 side is restricted.

The roller portion 50 has a roller 51 and a roller pin 52. The roller 51 contacts the cam 13,
The roller pin 52, which is integrally formed, can rotate about an axis. As shown in FIG. 1, a bush 53 is arranged between the roller 51 and the roller pin 52. The roller 51 is formed in an annular shape and has a bush 53 on the inner peripheral side.
The roller pin 52 is inserted through. The roller pin 52 is formed in a solid columnar shape. The roller portion 50 is installed on the drive shaft 12 side of the tappet 40, and the roller 51 is rotatably accommodated in a roller accommodating portion 41 formed in 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.

The tappet 40 is formed in a substantially cylindrical shape, and has a partition portion 43 near the center 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 part 43, one space is the plunger housing part 44 in which the plunger 30 is housed, and the other space is the roller housing part 41 in which the roller 51 is housed. A support portion 42 for supporting the roller pin 52 is provided at both axial ends of the roller 51 of the roller housing portion 41.
Is provided. As shown in FIG. 2, the plunger accommodating portion 44 accommodates the plunger 30.
A plunger head 32 is in contact with the end surface of the pressure chamber 3 on the side of the pressure chamber 31.

As shown in FIG. 3, the partition portion 43 has a through hole 4 for communicating the plunger accommodating portion 44 and the roller accommodating portion 41.
5 is formed. A part of the lubricating oil filling the tappet chamber 14 shown in FIG. 2 is supplied from the plunger accommodating portion 44 to the roller accommodating portion 41 via the through hole 45. The lubricating oil supplied to the roller accommodating portion 41 serves to lubricate between the roller 51 and the cam 13, and between both axial end portions of the roller 51 and the inner wall of the roller accommodating portion 41.

As shown in FIG. 2, the tappet 40 is a tappet chamber 14 formed inside the pump housing 10.
It can reciprocate inside, and the outer wall of the tappet 40 slides on the inner wall of the pump housing 10. As shown in FIG.
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 bell shape in a front view, and the length of the tappet 40 in the circumferential direction of the pressurizing chamber 31 is reduced from the upper end 46a to the lower end 46b. In addition, as shown in FIG.
61 has a bow-shaped cross section taken along the axis of the tappet 40, and has a recess 46 from the upper end 46a to the lower end 46b.
Is shallow. Therefore, FIG. 5 (A) and (B)
As shown in, the cross-sectional area of the recess 46 is larger toward the pressurizing chamber 31 side and decreases toward the drive shaft 12 direction. The end of the recess 46 on the drive shaft 12 side, that is, the lower end 4
6b communicates with the communication passage 47.

As shown in FIG. 3, the pressurizing chamber 3 of the recess 46 is shown.
The end portion on the first side, that is, the upper end portion 46a is the plunger housing portion 4
It communicates with 4. On the other hand, the lower end portion 46 b of the recess 46 communicates with the communication passage 47. One end of the communication passage 47 communicates with the recess 46, and the other end communicates with the support 42. As shown in FIG. 4, the communication passage 47 has a recess 46.
It is formed from the lower end portion 46b of the roller pin 52 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 so as to be inclined from the outer peripheral side of the tappet 40 to the inner peripheral side thereof.

When the tappet 40 rises in the tappet chamber 14 toward the pressurizing chamber 31, the lubricating oil filled in the tappet chamber 14 is filled with the plunger accommodating portion 44 of the tappet 40.
Flows into the recess 46. Since the tappet 40 and the pump housing 10 are sliding, when the tappet 40 rises in the direction of the pressurizing chamber 31, the lubricating oil that has flowed into the recess 46 has the tappet 4 due to the viscosity and inertia of the lubricating oil itself.
A force is applied in the direction opposite to the moving direction of 0, that is, in the direction of the drive shaft 12, and a force that flows in the direction of the lower end 46b of the recess 46 is exerted. Since the cross-sectional area of the recess 46 decreases in the direction of the drive shaft 12, the lubricating oil in the recess 46 increases in pressure 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 while being pressurized as the tappet 40 moves up. As a result, the lubricating oil that has flowed into the recess 46 from the plunger accommodating portion 44 is supplied to the support portion 42 via the communication passage 47.

Next, the operation of the fuel injection pump 1 of this embodiment will be described. By the rotation of the drive shaft 12, the drive shaft 1
The cam 13 integrated with 2 also rotates. Therefore, the roller 51 contacting the cam 13 reciprocates in the vertical direction of FIG.
Rotate around 2. As the roller 51 reciprocates in the vertical direction in FIG. 2, the tappet 40 supporting the roller 51 reciprocates 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 cylinder 21 in the vertical direction in FIG.

When the control valve 60 opens when the plunger 30 descends in the cylinder 21, that is, when the valve member 63 separates from the valve seat portion 64, the introduction pipe 22 and the fuel sump 23.
Is sucked into the pressurizing chamber 31 via the fuel supply passage 27 and the fuel supply passage 61. When the control valve 60 is closed, that is, when the valve member 63 is seated on the valve seat portion 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 unit 64, and the fuel in the pressurizing chamber 31 is supplied from the pressurizing chamber 31 as the plunger 30 moves up. It overflows to the fuel reservoir 23 via the passage 61 and the fuel supply passage 27.
Therefore, the fuel sucked into the pressurizing chamber 31 is not pressurized.

When fuel overflows 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, the fuel in the pressurizing chamber 31 starts to be pressurized as the plunger 30 moves up. When the fuel in the pressurizing chamber 31 is pressurized and the pressure of the fuel becomes larger than the biasing 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 opens and is pressurized. Fuel is discharged from the discharge hole 26
Is discharged to a common rail (not shown).

As described above, according to the fuel injection pump 1 according to the first embodiment of the present invention, the plunger accommodating portion 4 is provided.
The lubricating oil that has flowed into the recess 46 communicating with No. 4 communicates with the communication passage 47.
Is supplied to the support portion 42 via. As a result, the lubricating oil is supplied from the communication passage 47 to the sliding portion formed between the support portion 42 and the roller pin 52, so that the formation of the oil film on the sliding portion is promoted. Therefore, the tappet 40
It is possible to prevent the seizure of the sliding portion formed between the support portion 42 and the roller pin 52 of the roller portion 50.

Further, the recess 46 has a cross-sectional area that decreases in the direction of the drive shaft 12. Therefore, as the tappet 40 rises, the lubricating oil in the recess 46 is pressurized, and the lubricating oil pressurized in the recess 46 flows into the communication passage 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.

(Second Embodiment) FIG. 6 shows a tappet of a fuel injection pump according to a second embodiment of the present invention. The same components as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted. In the tappet 40 of the fuel injection pump according to the second embodiment, the communication passage 48 is formed at the first position as shown in FIG.
Different from the embodiment.

Similar to the first embodiment, the communication passage 48 connects the recess 46 and the support 42 and is formed so as to be inclined from the outer peripheral side to the inner peripheral side of the tappet 40. 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 shaft of the tappet 40 and the shaft of the communication passage 48 have a twisted relationship. In addition, the communication passage 48 has the roller pin 5
The opening is formed in the support portion 42 so as to be located on the rear side in the rotation direction of the No. 2. That is, when the roller pin 52 rotates in the direction of the arrow R, the end portion 48 a of the communication passage 48 on the side of the support portion 42 is located on the rear side in the rotation direction of the roller pin 52.

By the rotation of the roller pin 52, the supporting portion 42
The lubricating oil between the inner wall 42a of the roller pin 52 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 passage 48 is sucked toward the rear side in the rotational direction of the roller pin 52 whose pressure has decreased, and the roller pin 52 and the support portion 42 are then sucked.
Supplied between and.

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 by utilizing the effect of sucking the lubricating oil by the rotation of the roller pin 52. Therefore, the lubricating oil in the communication passage 48 smoothly flows into the support portion 4
2 can flow into the sliding portion between the roller pin 52 and the roller pin 52 to form an oil film. Therefore, it is possible to reliably prevent the seizure of the sliding portion formed between the supporting portion 42 and the roller pin 52.

In the above-described embodiments of the present invention, the fuel injection pump of the present invention is applied to the high pressure pump of the common rail fuel injection system. But,
The present invention is not limited to the common rail fuel injection system,
It can be applied to a high-pressure pump that pressurizes fuel in other fuel injection systems.

[Brief description of drawings]

FIG. 1 is a cross-sectional view taken along line I-I of FIG. 2 and is an enlarged view of the vicinity of a tappet.

FIG. 2 is a schematic sectional view showing a fuel injection pump according to the 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.

FIG. 4 is a view of the tappet as viewed from the direction of arrow IV in FIG.

5A is a schematic diagram showing a cross section of the dent portion taken along the line AA of FIG. 4, and FIG. 5B is a schematic diagram showing a cross section of the dent portion taken along the line BB of FIG. It is a figure.

FIG. 6 is a schematic view showing a tappet according to a second embodiment of the present invention, as viewed from the same direction as the arrow IV in FIG.

[Explanation of symbols]

1 Fuel injection pump 10 Pump housing (housing) 11 cam room 12 drive shaft 13 cams 20 Cylinder body (housing) 21 cylinders 30 Plunger 31 Pressurizing chamber 40 tappets 41 Roller housing 42 Support 43 partition 44 Plunger housing 46 recess 47, 48 communication passage 50 Roller part 51 Laura 52 Roller pin

Claims (3)

[Claims] 1. A plunger for pressurizing fuel sucked into a pressurizing chamber, a cam chamber at one end, and a plunger reciprocally supported at the other end for supporting the pressurizing chamber together with the plunger. A housing having a cylinder to be formed, a cam housed in the cam chamber and rotating with a drive shaft, a roller contacting with the cam, and a roller pin in which the roller is integrally assembled, the roller being the cam. By moving along the profile surface of
A roller portion that moves in the reciprocating direction of the plunger while rotating around the roller pin, a plunger accommodating portion that accommodates the plunger, a support portion that rotatably supports the roller pin, and a roller that rotatably accommodates the roller. The housing portion, a recess portion formed in the outer peripheral portion and communicating with the plunger housing portion and having a cross-sectional area that decreases in the drive axis direction, and an end portion of the recess portion on the side opposite to the plunger housing portion and the support portion. A fuel injection pump, comprising: a tappet having a communication passage communicating with each other and transmitting a reciprocating movement of the roller portion to the plunger. 2. The fuel injection pump according to claim 1, wherein the communication passage is formed toward a central axis of the roller pin. 3. The communication passage is formed in a tangential direction of the roller pin, and an end portion of the communication passage on the side of the support portion communicates with a rear side in a rotation direction of the roller pin. The fuel injection pump described.