JP2003184682A - Fuel injection pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel injection pump for preventing reverse rotation of a feed pump and preventing leakage of fuel together with rising of fuel pressure in the feed pump. <P>SOLUTION: A one-way clutch 50 is installed between an inner rotor 41 of a feed pump 40 for supplying fuel to a pressure chamber and a driving shaft 15. The one-way clutch 50 transmits a driving force of the driving shaft 15 to the inner rotor 41 at the time of regular rotation of the feed pump 40 for supplying fuel to the pressure chamber. The one-way clutch 50 cancels transmission of the driving force from the driving shaft 15 to the inner rotor 41 at the time of reverse rotation of the feed pump 40. This prevents reverse rotation of the feed pump 40, and prevents pressure rising in the feed pump 40 caused by reverse rotation, and leakage of fuel caused by the temperature rising. <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." ) Fuel injection pump.

[0002]

2. Description of the Related Art A common rail type fuel injection system applied to, for example, a diesel engine includes a fuel injection pump for pressurizing fuel and feeding the fuel to the common rail.
The fuel injection pump includes a feed pump that feeds the fuel stored in the fuel tank to the pressurizing chamber. The fuel fed to the pressurizing chamber is pressurized by the movable member reciprocally driven by the drive shaft and fed to the common rail.
The feed pump is driven by the drive shaft similarly to the movable member. As the feed pump, for example, a trochoid type pump having an inner rotor and an outer rotor is used. An inner rotor is integrally attached to the drive shaft, and the inner rotor and the outer rotor rotate relative to each other as the drive shaft rotates. As a result, the fuel stored in the fuel tank is sucked into the feed pump and supplied to the pressurizing chamber.

[0003]

The feed pump is configured to supply fuel from the fuel tank to the pressurizing chamber when the relative rotation between the inner rotor and the outer rotor is in the predetermined forward direction. Therefore, when the inner rotor and the outer rotor rotate in reverse, which is the reverse of normal rotation, the fuel drawn into the feed pump is not discharged.

However, when the fuel injection pump is assembled, if the feed pump is installed in the wrong direction with respect to the housing of the fuel injection pump, the feed pump may rotate in the reverse direction. In addition, the diesel engine may reversely rotate due to its characteristics depending on operating conditions. In such a case, the fuel drawn into the feed pump is not discharged from the feed pump, and the pressure of the fuel inside the feed pump rises. Therefore, there is a problem that fuel is leaked from the feed pump.

Therefore, an object of the present invention is to provide a fuel injection pump which prevents reverse rotation of the feed pump and prevents fuel leakage due to increase in fuel pressure in the feed pump.

[0006]

According to the fuel injection pump of the first aspect of the present invention, a driving force connecting / disconnecting means for connecting / disconnecting the driving force depending on the rotating direction of the inner rotor is provided between the drive shaft and the inner rotor of the feed pump. I have it. The drive force connecting / disconnecting means transmits the drive force of the drive shaft to the inner rotor when the feed pump rotates forward. On the other hand, when the feed pump rotates in the reverse direction, the transmission of the driving force from the drive shaft to the inner rotor is released. In this specification, the forward rotation refers to the rotation direction of the feed pump when fuel is supplied from the feed pump to the pressurizing chamber. Reverse rotation means rotation in the opposite direction to normal rotation. By disposing the drive force connecting / disconnecting means between the drive shaft and the inner rotor, it is possible to prevent the fuel pressure from increasing in the feed pump due to the reverse rotation of the drive shaft or the reverse rotation of the feed pump. Therefore, it is possible to prevent the fuel from leaking due to the increase in the pressure of the fuel in the feed pump, and it is possible to improve the reliability.

According to the second aspect of the fuel injection pump of the present invention, the driving force connecting / disconnecting means has a one-way clutch. Therefore, it is possible to reliably release the driving force from the drive shaft to the inner rotor during reverse rotation.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment showing an embodiment of the present invention will be described below with reference to the drawings. A fuel injection pump according to an embodiment of the present invention is shown in FIG. Fuel injection pump 1
Is applied to a common rail fuel injection system.

The housing 10 of the fuel injection pump 1 has a housing body 11 and cylinder heads 12 and 13. The housing body 11 is made of aluminum. The cylinder heads 12 and 13 are made of iron, and the plungers 2 as movable members are attached to the cylinders 12a and 13a formed inside.
0 is supported so that it can move back and forth. Cylinder head 1
A pressurizing chamber 30 is formed by the inner peripheral surfaces of 2 and 13, the end surface of the check valve 14, and the end surface of the plunger 20. In this embodiment, the cylinder head 12 and the cylinder head 13 are formed in substantially the same shape, but the forming positions of screw holes, fuel passages, etc. are different. On the other hand, it is also possible to form the screw holes and the fuel passages at the same position and to make the cylinder head 12 and the cylinder head 13 have the same shape.

The drive shaft 15 is rotatably supported by the housing 10 via a journal 16. Housing 1
An oil seal 17 seals between 0 and the drive shaft 15. As shown in FIG. 3, the cam 2 has a circular cross section.
1 is eccentrically formed with respect to the drive shaft 15 and is integrally formed.
The two plungers 20 are 180 ° across the drive shaft 15.
It is located on the opposite side. The cam ring 22 has a quadrangular outer shape, and a cam ring 22 and a bush 23 slidable on the cam 21 are interposed between the cam ring 22 and the cam 21. The outer peripheral surface of the cam ring 22 facing the plunger 20 and the end surface of the plunger 20 are formed in a flat shape and are in contact with each other. Drive shaft 15, cam 2
1, the cam ring 22 and the spring 24 constitute a driving means for driving the plunger 20.

The plunger 20 is reciprocally driven by a cam 21 via a cam ring 22 as the drive shaft 15 rotates, and passes from the fuel inflow passage 18 through the check valve 14 to the pressurizing chamber 30.
Pressurize the fuel drawn into. The check valve 14 is a valve member 141.
To prevent the fuel from flowing backward from the pressurizing chamber 30 to the fuel inflow passage 18.

The spring 24 urges the plunger 20 toward the cam ring 22. As the cam 21 rotates, the cam ring 22 slides on the cam 21 and revolves without rotating. As a result, the cam ring 22 and the plunger 20 that form the sliding portion slide while reciprocating in the left-right direction in FIG.

The fuel discharge passage 31 is provided in the cylinder head 12
The cylinder head 13 and the cylinder head 13 are linearly formed and communicate with the pressurizing chamber 30. Cylinder head 1
On the downstream side of the fuel discharge passage 31 formed in Nos. 2 and 13, an elongated hole-shaped fuel chamber 32 having a passage area larger than that of the fuel discharge passage 31 is formed, and a check valve 33 is accommodated in the fuel chamber 32. ing. An accommodation hole 34 having a larger passage area than the fuel chamber 32 is formed on the fuel downstream side of the fuel chamber 32. The connection member 35 for connecting the fuel pipe is housed in the housing hole 34 by screwing or the like. A fuel passage 36 is formed inside the connecting member 35, and the fuel passage 36 communicates with the fuel chamber 32. The fuel passage 36 is formed substantially on the same straight line as the fuel discharge passage 31.

The check valve 33 disposed on the fuel downstream side of the fuel discharge passage 31 of the cylinder heads 12 and 13 is a pressurizing chamber 30 from the fuel downstream side of the check valve 33 via the fuel discharge passage 31. Prevent backflow of fuel to the. Connection member 3
Reference numeral 5 is connected to a common rail (not shown), and the fuel pressurized by the fuel injection pump 1 is supplied to the common rail via a fuel passage 36 formed in the connecting member 35 and a fuel pipe (not shown). On the common rail, the fuel discharged from the fuel injection pump 1 is stored in a pressure-accumulated state. An injector (not shown) installed in each cylinder of the engine (not shown) is connected to the common rail, and the high-pressure fuel stored in the common rail is supplied to the injector. The injector is not shown in the ECU
The fuel supplied from the common rail is injected into each cylinder of the engine at a predetermined time and for a predetermined period in accordance with a command from.

A feed pump 40 is provided at the end of the drive shaft 15.
Is provided. The feed pump 40 has an inner rotor 41 and an outer rotor 42. The inner rotor 41 and the outer rotor 42 are provided so as to be relatively rotatable. The inner rotor 41 and the outer rotor 42 that form the feed pump 40 are housed in a pump cover 43. As shown in FIG. 1, the inner rotor 41
Is installed on the drive shaft 15 via a one-way clutch 50 as a drive force connecting / disconnecting means. Feed pump 40
Is a trochoidal pump,
The outer peripheral side has an inner gear 41a formed by a trochoid curve, and the inner peripheral side of the outer rotor 42 has an outer gear 42a formed by a trochoid curve. As the inner rotor 41 and the outer rotor 42 rotate relative to each other, the inner gear 41a and the outer gear 4
The volume between 2a and 2a is changed. As a result, the feed pump 40 draws fuel from a fuel tank (not shown) and discharges it into the pressurizing chamber 30.

As shown in FIG. 2, a transmission portion 15a is formed at the end of the drive shaft 15 on the side opposite to the feed pump.
The transmission portion 15a is connected to a crankshaft of an engine (not shown). As a result, the drive shaft 15 is rotationally driven by the drive force transmitted from the crankshaft of the engine.

As shown in FIG. 1, the feed pump 40 has a suction port 44 and a discharge port 45. The intake port 44 communicates with the fuel tank, and the fuel pumped up from the fuel tank flows. Discharge port 4
5 communicates with the pressurizing chamber 30 via the fuel inflow path 18, and the fuel pressurized by the feed pump 40 flows.

The one-way clutch 50 transmits a driving force from the drive shaft 15 to the inner rotor 41 when the feed pump 40 is rotated in a predetermined rotation direction, that is, forward rotation. On the other hand, the one-way clutch 50 releases the transmission of the driving force from the drive shaft 15 to the inner rotor 41 when the feed pump 40 is reversely rotated in the opposite direction to the normal rotation.

The one-way clutch 50 has a structure as shown in FIGS. 4 and 5, for example. A spherical or cylindrical rotating member 53 is provided between an inner ring 51 mounted on the outer peripheral side of the drive shaft 15 and an outer ring 52 mounted on the inner peripheral side of the inner rotor 41. The outer ring 52 has a recess 5 that forms a housing chamber 54 in which the rotating member 53 is housed between the outer ring 52 and the inner ring 51.
5 is formed. The concave portion 55 projects outward in the radial direction of the outer ring 52 and forms a housing chamber 54 having a different size in the circumferential direction between the outer ring 52 and the inner ring 51. Containment room 5
4 has a large diameter portion 541 on one side and a small diameter portion 542 on the other side. The large diameter portion 541 of the accommodation chamber 54 is
The rotating member 53 is formed to have a diameter larger than the outer diameter of the rotating member 53.
3 is rotatably accommodated. The small diameter portion 542 of the accommodation chamber 54 is formed in a wedge shape in which the distance between the inner ring 51 and the outer ring 52 decreases in the circumferential direction. Further, the small diameter portion 542 is formed smaller than the outer diameter of the rotating member 53, and the rotation member 53 is housed in the wedge-shaped small diameter portion 542, so that the rotation is restricted.

Therefore, when the feed pump 40 is normally rotated with the rotation of the drive shaft 15, the inner ring 51 attached to the drive shaft 15 rotates in the direction of arrow A shown in FIG. Along with this, the rotating member 53 is housed in the small diameter portion 542 of the housing chamber 54, and the rotation of the rotating member 53 is restricted. As a result, the driving force of the drive shaft 15 is transmitted to the inner ring 51 via the rotating member 53. Therefore, when the feed pump 40 is rotating normally, the drive shaft 1
With the rotation of 5, the inner rotor 41 is rotationally driven.

On the other hand, when the feed pump 40 is rotated in the reverse direction, the inner ring 5 mounted on the drive shaft 15 is rotated.
1 rotates in the direction of arrow B shown in FIG. Along with this, the rotating member 53 is rotatably housed in the large diameter portion 541 of the housing chamber 54. As a result, the rotating member 53 rotates in the direction of arrow C shown in FIG. 5, and the driving force of the drive shaft 15 is not transmitted to the inner rotor 41. Therefore, the feed pump 4
When 0 is the reverse rotation, the transmission of the driving force to the inner rotor 41 is released, and the inner rotor 41 is not rotationally driven.

Next, the operation of the fuel injection pump 1 according to one embodiment of the present invention will be described. The inner rotor 41 of the feed pump 40 rotates as the drive shaft 15 rotates. The inner rotor 41 and the outer rotor 42 of the feed pump 40 rotate relative to each other, so that the feed pump 40 pumps up the fuel stored in the fuel tank. The pumped fuel is pressurized when being fed from the intake port 44 to the discharge port 45. The pressurized fuel is supplied from the discharge port 45 to the pressurizing chamber 30 via a metering valve (not shown) and the fuel inflow passage 18. A metering valve installed between the feed pump 40 and the pressurizing chamber 30 adjusts the flow rate of the fuel flowing into the pressurizing chamber 30.

The fuel which has passed through the metering valve is sucked into the pressurizing chamber 30 when the plunger 20 descends in the cylinder 12a or the cylinder 13a as the drive shaft 15 rotates. Then, the plunger 20 is connected to the cylinder 12a or 1
The fuel in the pressurizing chamber 30 is pressurized by ascending in 3a. When the fuel in the pressurizing chamber 30 reaches a predetermined pressure, the check valve 33 in the fuel discharge passage 31 communicating with the pressurizing chamber 30 opens, and the fuel in the pressurizing chamber 30 is discharged to a common rail (not shown). In the common rail, the fuel supplied from the fuel injection pump 1 is kept at a constant pressure in a pressure accumulation state. The fuel stored in the common rail is supplied to an injector (not shown) and is injected from the injector into each cylinder of the engine.

As described above, in the fuel injection pump 1 according to the embodiment of the present invention, the one-way clutch 50 is installed between the drive shaft 15 and the inner rotor 41 to prevent the feed pump 40 from rotating in the reverse direction. There is. Therefore, when the feed pump 40 rotates in the reverse direction, the drive shaft 1
The transmission of the driving force from 5 to the inner rotor 41 is released. As a result, the pressure increase of the fuel in the feed pump 40 due to the reverse rotation of the feed pump 40 is prevented. Therefore, it is possible to prevent fuel leakage due to increase in fuel pressure in the feed pump 40 and damage to the feed pump 40. Also, the one-way clutch 50
By installing, it is possible to reliably release the transmission of the driving force from the drive shaft 15 to the inner rotor 41 when the feed pump 40 rotates in the reverse direction.

In the above-described embodiment of the present invention, the one-way clutch using the rotating member has been described.
Other types of one-way clutches can be applied. Further, the driving force transmitting means is not limited to the one-way clutch as long as it discontinues the driving force depending on the rotation direction.

[Brief description of drawings]

FIG. 1 is a schematic arrow view showing a fuel injection pump according to an embodiment of the present invention as viewed in the direction of arrow I in FIG. 2, showing a state in which a part of a pump cover is cut off.

FIG. 2 is a schematic cross-sectional view showing a fuel injection pump according to an embodiment of the present invention.

FIG. 3 is a sectional view taken along line III-III in FIG.

FIG. 4 is a schematic view showing a one-way clutch of the fuel injection pump according to the embodiment of the present invention, and is a view showing a state in which the feed pump is in the normal rotation and the driving force is transmitted.

FIG. 5 is a schematic view showing a one-way clutch of the fuel injection pump according to the embodiment of the present invention, showing a state in which the feed pump is reversely rotated and the transmission of the driving force is released.

[Explanation of symbols]

1 Fuel injection pump 15 drive shaft 20 Plunger (movable member) 21 cam (driving means) 22 Cam ring (driving means) 24 Spring (drive means) 30 pressure chamber 40 feed pump 41 Inner rotor 42 Outer rotor 50 One-way clutch (Driving force connecting / disconnecting means)

Claims (2)

[Claims] 1. A movable member for pressurizing fuel sucked into a pressurizing chamber, a driving unit having a drive shaft for driving the movable member, an inner rotor rotatably driven together with the drive shaft, and the inner rotor. A feed pump that has an outer rotor that is relatively rotatable, and that can supply fuel to the pressurizing chamber by rotating the inner rotor and the outer rotor relative to each other, and is disposed between the inner rotor and the drive shaft. When the feed pump supplies the fuel to the pressurizing chamber in the forward rotation, the driving force is transmitted from the drive shaft to the inner rotor, and in the reverse rotation in the direction opposite to the forward rotation, the drive shaft transmits the drive force to the inner shaft. A fuel injection pump, comprising: a driving force connecting / disconnecting means for canceling the transmission of the driving force to the inner rotor. 2. The fuel injection pump according to claim 1, wherein the driving force connecting / disconnecting means has a one-way clutch.