JP2000045907A - Fuel pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel pump capable of maintaining the discharging ability for a longer period of time and improving the durability. SOLUTION: This fuel injection pump 10 includes a pump body 12, a fuel pressurizing chamber 15 formed within the pump body 12, and a plunger 17 for pressurizing fuel within the fuel pressurizing chamber 15. A barrel 13 is inserted into the pump body 12 and supports the plunger 17 to permit reciprocating motion. The barrel 13 is supported by an inner peripheral surface of the pump body 12 to permit reciprocating motion. A cylindrical portion 29 is screwed into the pump body 12 at the upper portion of the barrel 13. A rubber ring 26 is interposed in a clearance 27 between a lower end of the cylindrical portion 29 and an upper end of the barrel 13 and elastically supports the barrel 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel pump for supplying fuel to, for example, an internal combustion engine or the like. More specifically, the present invention relates to a plunger for pressurizing fuel in a fuel pressurizing chamber formed in a pump body, and a reciprocating pump. And a plunger barrel movably supported.

[0002]

2. Description of the Related Art FIG. 4 shows a schematic configuration of a conventional fuel pump. The fuel pump 100 supplies fuel to an internal combustion engine, and includes a fuel pressurizing chamber 112 formed in a pump main body 102 and a plunger 106 for pressurizing the fuel in the fuel pressurizing chamber 112. . The plunger 106 is reciprocally supported by a plunger barrel 104 fixed to the pump body 102. The plunger 106 is driven reciprocally by rotation of a cam formed on a camshaft, a crankshaft, or the like. The pump body 102 has a supply port 108 and a discharge port 1
The fuel is supplied from the supply port 108 to the fuel pressurizing chamber 112 with the reciprocation of the plunger 106, and the fuel pressurized in the fuel pressurizing chamber 112 is discharged from the discharge port 110. Discharged.

[0003]

By the way, as shown in FIG. 4, the reciprocating driving force that should originally act on the plunger 106 so as to coincide with the direction of the axis (dashed line) of the plunger 106 is the same. As shown by the two-dot chain line in the figure,
In some cases, it acts slightly inclined with respect to the coaxial line. Each of the sliding surfaces of the plunger 106 and the plunger barrel 104 usually has a plurality of convex portions when viewed microscopically. For this reason, this kind of fuel pump 100 has the following problems.

FIG. 5 shows a plunger barrel 10 as described above.
4 shows a state in which the plunger 106 reciprocates in a state of being inclined with respect to 4 (the inclination angle is exaggerated in the figure).

When the plunger 106 moves from the state shown in FIG. 1A to the state shown in FIG. 1B, a protrusion (exaggerated in size in FIG. Plunger 10 in FIG.
6 comes into contact with the plunger barrel 104,
Because the contact area is greatly reduced and the surface pressure increases rapidly,
An impact shear stress acts on the contact portion between the two 104 and 106. When such a shocking shear stress acts, not only does the abrasion of the sliding portion increase sharply, but also thermal damage such as seizure occurs.

In the conventional fuel pump 100, since fuel leakage occurs due to such wear of the sliding portion, it is difficult to maintain the discharge capability for a long period of time, and the fuel pump 100 has durability due to heat damage such as seizure. A decline in sex was unavoidable.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to maintain the discharge capability of a plunger and a plunger barrel for a long period of time by reliably suppressing the occurrence of wear and thermal damage in a sliding portion thereof. It is another object of the present invention to provide a fuel pump capable of improving durability.

[0008]

In order to achieve the above object, according to the present invention, there is provided a plunger for pressurizing fuel in a fuel pressurizing chamber formed in a pump body, and a plunger provided in the pump body. And a plunger barrel for reciprocally supporting the plunger, the plunger barrel is supported by the pump body so as to be movable in the reciprocating direction of the plunger.

According to this configuration, when an impact shear stress is applied to the sliding portion between the plunger and the plunger barrel, the plunger barrel moves in the same direction as the plunger and the shear stress is reduced. Become.
Therefore, the occurrence of wear and thermal damage in the sliding portion is suppressed. Further, since the sliding speed of the plunger and the plunger barrel is reduced by the movement of the plunger barrel, the amount of wear can be reduced in this respect as well.

When the plunger barrel is configured to be movable as described above, a sliding portion also exists between the plunger barrel and the pump body, and abrasion occurs at the sliding portion, and the fuel is removed. It is feared that will be leaked. However, even if the portion where fuel leakage occurs increases as described above, the discharge performance of the fuel pump does not decrease as compared with the conventional configuration for the following reason.

That is, the sum of the sliding speed between the plunger and the plunger barrel and the sliding speed between the plunger barrel and the pump body is the same as that in the conventional structure in which the plunger barrel is fixed to the pump body. Equal to the sliding speed between the plunger and the plunger barrel. Here, it is known that the clearance between the sliding surfaces increases due to wear of both sliding surfaces, and the increasing speed is proportional to the sliding speed of the sliding surfaces. Therefore, in the configuration of the present invention, the sum of the increase in the clearance between the plunger and the plunger barrel and between the plunger barrel and the pump body, and in the conventional configuration, the increase in the clearance between the plunger and the plunger barrel Is equal to

The amount of fuel leakage at the sliding portion changes according to the size of the clearance, and it is well known that the amount of fuel leakage is proportional to the cube of the size of the clearance. Therefore, if the amount of increase in the clearance is the same as described above, even if fuel leakage occurs between the plunger barrel and the plunger barrel by adopting a configuration in which the plunger barrel can be moved relative to the pump body, Obviously, the total amount of fuel leakage is smaller than in the conventional configuration in which the clearance between them can be excessive. Therefore, the adoption of the configuration of the present invention does not lower the discharge capacity of the fuel pump.

Further, when the plunger barrel is supported by the pump body so as to be movable in the reciprocating direction of the plunger, it is preferable that the pump body and the plunger barrel be moved in the reciprocating direction of the plunger. It is possible to employ a configuration in which an elastic member interposed therebetween and elastically supporting the plunger barrel is further provided.

According to such a configuration, in addition to the effect of the invention described in claim 1, the collision between the plunger barrel and the pump body due to the movement of the plunger barrel is reduced.

An elastic member interposed between the pump body and the plunger barrel in a direction perpendicular to the reciprocating direction of the plunger to elastically support the plunger barrel. Further comprising
If such a configuration is adopted, in addition to the effect of the invention described in claim 1 or 2, even if the plunger is inclined,
Since the plunger barrel can also be inclined in accordance with the inclination, it is possible to suppress uneven contact surface pressure between the two.

According to the invention described in claim 4, one end of the plunger barrel located on the same side as the movement direction of the plunger when pressurizing the fuel in the fuel pressurizing chamber is connected to the other end. A biasing member for biasing toward the side; a fuel pressure supply passage for supplying the fuel pressure of the fuel pressurizing chamber to the vicinity of the other end so as to bias the other end toward the one end. Is adopted, it becomes possible to reciprocate the plunger barrel more positively in accordance with the reciprocation of the plunger. That is, when the fuel pressure in the fuel pressurizing chamber increases with the forward movement of the plunger, the fuel pressure is supplied to the other end of the plunger barrel through the fuel pressure supply passage, and the plunger barrel is moved to one end by the fuel pressure. It moves in the same direction as the unit side, that is, the fuel pressurizing direction (forward direction) of the plunger. On the other hand, when the fuel pressure in the fuel pressurizing chamber decreases with the return of the plunger, the plunger barrel is moved to the other end side by the urging force of the urging member.
That is, the plunger moves in the same direction as the fuel suction direction (return direction).

Therefore, according to the above configuration, in addition to the function of the invention described in any one of the first to third aspects, the plunger barrel always reciprocates in the same direction in synchronization with the reciprocation of the plunger. Therefore, the sliding speed between the plunger and the plunger barrel is surely reduced, and the amount of wear between the two is further reduced.

According to the present invention, at least one of a supply passage for supplying fuel to the fuel pressurizing chamber and a discharge passage for discharging fuel from the fuel pressurizing chamber is formed on the outer peripheral surface of the plunger. If a configuration having an opening is adopted, fuel is supplied as lubricating oil between the plunger and the plunger barrel, and the sliding resistance between the two is reduced.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] A first embodiment in which the present invention is applied to a fuel injection pump of a direct injection gasoline engine will be described below.

FIG. 1 is a sectional view showing a fuel injection pump 10 according to this embodiment mounted on a cylinder head 20 of an engine. The fuel injection pump 10 includes a pump body 12 and a fuel pressurizing chamber 1 formed in the pump body 12.
5 and a plunger 17 for pressurizing the fuel in the fuel pressurizing chamber 15.

The pump body 12 has a substantially cylindrical shape.
A plurality of mounting portions 14 extending laterally are formed integrally at a substantially central portion in the longitudinal direction. Pump body 12
The lower end portion (lower portion in FIG. 1) of the mounting portion 14 is fixed to the cylinder head 20 with bolts 16 so that the mounting portion 14 is fixed to the mounting hole 20 of the cylinder head 20.
a and is attached to the cylinder head 20 in a state where it is inserted into the cylinder head 20.

A plunger barrel 13 is inserted into the pump body 12 from the upper end side (the upper side in FIG. 1). The plunger barrel 13 is supported by the inner peripheral surface of the pump body 12 so as to be able to reciprocate. Pump body 12
Is formed with an inner flange 19, by which the lower end of the plunger barrel 13 is locked. A cylindrical portion 29 is screwed above the plunger barrel 13 inside the pump body 12.

A rubber ring 26 is interposed in a gap 27 between the lower end of the cylindrical portion 29 and the upper end of the plunger barrel 13, and the plunger barrel 13 is elastically supported by the rubber ring 26. The rubber ring 26 is formed of a material having excellent fuel resistance such as NBR rubber, for example. The plunger barrel 13 can move toward the cylindrical portion 29 because the rubber ring 26 is elastically deformed and its thickness (the length in the vertical direction in FIG. 1) is reduced.

The plunger 17 has an upper end portion (an upper portion in FIG. 1) inserted into the plunger barrel 13 and is supported by the inner peripheral surface of the plunger barrel 13 so as to be able to reciprocate. The lower end of the plunger 17 extends below the inner flange 19 inside the pump body 12, and a retainer 23 is attached to the lowermost end thereof. The retainer 23 and the inner flange 19
A coil spring 25 is disposed between the two.

A bottomed cylindrical lifter 21 is inserted into the pump body 12 from the lower end thereof, and the lifter 21 is fixed to a retainer 23. A cam 24 for pump driving is formed on a cam shaft 22 rotatably supported by the cylinder head 20.
The bottom of the lifter 21 is provided on the outer peripheral surface of the coil spring 25.
Abuts on each other while being pressed by the urging force of

The fuel pressurizing chamber 15 is formed by a space in the plunger barrel 13 above the upper end surface of the plunger 17 and a space between the plunger barrel 13 and the cylindrical portion 29 on the inner peripheral side of the rubber ring 26. Have been. The cylindrical portion 29 includes a supply portion 30 for supplying fuel into the fuel pressurizing chamber 15 and a discharge portion 40 for discharging fuel pressurized in the fuel pressurizing chamber 15 to the outside. Is provided.

The supply section 30 is a supply pipe 3 connected to a fuel tank (both not shown) via a fuel feed pump or the like.
7 and a check valve 3 provided inside the cylindrical portion 29
2 and a bolt 31 for fixing the end of the supply pipe 37 to the column 29. An internal hole 31 a connecting the supply pipe 37 and the check valve 32 is formed inside the bolt 31. The check valve 32 regulates the flow of fuel from the fuel pressurizing chamber 15 to the supply unit 30 side.
3 is connected to the fuel pressurizing chamber 15.

The discharge part 40 includes a discharge pipe 43 connected to a delivery pipe (all not shown) for distributing fuel to a plurality of injectors, a check valve 44 provided inside the cylindrical part 29, and a cylindrical part 29. The union 42 is fixed and connected to the end of the discharge pipe 43. Inside the union 42, an internal hole 42a for connecting the discharge pipe 43 and the check valve 44 is formed. The check valve 44 is for restricting the flow of fuel from the discharge part 40 to the fuel pressurizing chamber 15 side, and
9 is connected to the fuel pressurizing chamber 15 by a passage 46 formed therein.

The fuel injection pump 1 constructed as described above
0, the coil spring 2
When the lifter 21 moves down by the urging force of 5, the plunger 17 moves down, and the fuel pressure in the fuel pressurizing chamber 15 decreases. As a result, the check valve 32 of the supply unit 30 is opened, and fuel is introduced from the supply unit 30 into the fuel pressurizing chamber 15.

On the other hand, as the cam 24 rotates, the lifter 21
Is pushed up by the cam 24 against the urging force of the coil spring 25, the plunger 17 moves upward and the fuel in the fuel pressurizing chamber 15 is pressurized. As a result, the discharge unit 40
Is opened, and the fuel in the fuel pressurizing chamber 15 is discharged from the discharge part 40 to the delivery pipe through the discharge pipe 43.

Here, the fuel injection pump 10 of the present embodiment
Here, the plunger barrel 13 is reciprocally supported by the pump body 12 and a rubber ring 26 is interposed between the lower surface of the cylindrical portion 29 and the upper surface of the plunger barrel 13. Therefore, when the shear stress in the sliding portion between the plunger 17 and the plunger barrel 13 increases when the plunger 17 moves upward, the rubber ring 26 is pressed between the plunger barrel 13 and the cylindrical portion 29. . As a result, the rubber ring 26 is elastically deformed and its thickness is reduced, and the plunger barrel 13 is moved upward with the decrease, so that an impact shearing is applied to the sliding portion between the plunger barrel 13 and the plunger 17. The stress is suppressed from acting.

(1) Therefore, according to the present embodiment, the occurrence of wear and thermal damage in the sliding portion between the plunger 17 and the plunger barrel 13 is suppressed. Furthermore, since the sliding speed between the plunger 17 and the plunger barrel 13 is reduced by the upward movement of the plunger barrel 13, the amount of wear can be reduced in this respect as well. As a result, the discharge capacity of the fuel injection pump 10 can be maintained for a long period of time, and the durability thereof can be improved.

The fuel injection pump 1 according to the present embodiment
In the case of 0, the sliding portion exists between the plunger barrel 13 and the pump body 12, but there is no possibility that the discharge capacity of the fuel injection pump 10 is reduced as described above.

(2) Further, in the present embodiment, the rubber ring 2 interposed between the plunger barrel 13 and the cylindrical portion 29
By virtue of 6, even when the plunger barrel 13 moves upward as described above, the upper surface of the plunger barrel 13 does not directly contact the pump main body 12, and the collision between the two 12, 13 is reduced. As a result, it is possible to suppress the generation of abnormal noise due to the collision between the plunger barrel 13 and the pump body 12. [Second Embodiment] Next, a second embodiment will be described focusing on differences from the first embodiment. The same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

As shown in FIG. 2, the plunger barrel 13
A gap 55 is formed between the rubber ring 26 and the inner flange 19.
A rubber ring 54 formed of a material having excellent fuel resistance such as R rubber is interposed. Plunger barrel 13
Is elastically supported by a rubber ring 26 disposed between the cylindrical portion 29 and the rubber ring 54, and the plunger barrel 13 moves up and down by elastic deformation of the rubber rings 26 and 54. It is possible.

The outer peripheral surface of the plunger barrel 13 is formed with two circumferential grooves 50 and 51 extending in the circumferential direction.
As in the rubber ring 26, N
Rubber rings 52 and 53 formed of a material having excellent fuel resistance such as BR rubber are fitted respectively. The plunger barrel 13 is elastically supported by the outer peripheral surfaces of the rubber rings 52 and 53 contacting the inner peripheral surface of the pump body 12. In the present embodiment, the rubber rings 52 and 53 slide on the inner peripheral surface of the pump body 12 and also undergo shear deformation in the vertical direction, thereby allowing the plunger barrel 13 to move up and down. I have.

The outer diameter of the plunger barrel 13 is slightly smaller than the inner diameter of the pump body 12, and a small gap is formed between the outer peripheral surface of the plunger barrel 13 and the inner peripheral surface of the pump body 12. ing.

The same effects as (1) and (2) described in the first embodiment can also be obtained by the fuel injection pump 10 of the present embodiment configured as described above.

(3) Further, in the present embodiment, since the rubber ring 54 is disposed between the plunger barrel 13 and the inner flange 19, not only when the plunger 17 moves up but also when it moves down. In the plunger 17
The impact of a shocking shear stress on the sliding portion between the piston and the plunger barrel 13 is suppressed. Therefore, according to the present embodiment, the effects described in the above (1) and (2) can be more reliably achieved.

In this embodiment, rubber rings 52 and 53 are also provided on the outer periphery of the plunger barrel 13, and the rubber rings 52 and 53 are used by the rubber rings 52 and 53.
Are elastically supported in the radial direction, in other words, in the direction perpendicular to the vertical movement direction of the plunger 17. Therefore, even if the axis of the plunger 17 is inclined, the plunger barrel 13 can also be inclined in accordance with the inclination.

(4) As a result, according to this embodiment, the contact surface pressure between the plunger 17 and the plunger barrel 13 is suppressed from becoming non-uniform, whereby
The occurrence of abrasion and thermal damage in the sliding portion between 7 can be more reliably suppressed. [Third Embodiment] Next, a third embodiment will be described focusing on differences from the first embodiment. The same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

As shown in FIG. 3, in this embodiment, the discharge section 40 is provided on the side of the pump body 12. The lower end portion of the cylindrical portion 29 has its central portion reduced in diameter and extended downward, and is inserted into the plunger barrel 13 from the upper end side. A fuel pressurizing chamber 15 is formed in the plunger barrel 13 between the extended portion of the cylindrical portion 29 and the plunger 17.

In the first embodiment, the rubber ring 26 provided between the plunger barrel 13 and the cylindrical portion 29 is omitted, and instead of the rubber ring 26, a coil spring is provided between the two. 60 are provided. The plunger barrel 13 is provided with the coil spring 60.
Thus, it is elastically supported while being urged toward the inner flange 19 side.

At the lower end of the plunger barrel 13, a portion surrounding the plunger 17 is cut off obliquely, and the cut surface of the inclined surface 61 a and the inner flange 19 are cut off.
The pressure chamber 61 is defined by an annular space surrounded by the upper surface of the pressure sensor and the outer peripheral surface of the plunger 17.
The inner peripheral surface of the inner flange 19 is in contact with the outer peripheral surface of the plunger 17 to prevent fuel from leaking from the pressure chamber 61.

The plunger 1 is provided inside the plunger 17.
7. A communication hole 62 having openings on the upper end surface and the outer peripheral surface, respectively.
Are formed, and the communication pressurizing chamber 1 is
5 and the pressure chamber 61 are communicated. A communication hole 67 is formed in the lower end portion of the plunger barrel 13 and opens to the outer peripheral surface, and a passage 66 communicating with the communication hole 67 is formed in the pump body 12. The pressure chamber 61 is connected to the check valve 44 through the communication hole 67 and the passage 66.

In the fuel injection pump 10 according to the present embodiment having the above-described configuration, when the fuel in the fuel pressurizing chamber 15 is pressurized by the upward movement of the plunger 17, the check valve 44 is opened. The fuel in the fuel pressurizing chamber 15 is introduced into the pressure chamber 61 through the communication hole 62 of the plunger 17. Further, the fuel introduced into the pressure chamber 61 is supplied to the communication hole 6.
The liquid is discharged from the discharge part 40 to the delivery pipe through the passage 7 and the passage 66.

When the fuel pressurized as described above is introduced into the pressure chamber 61, the fuel pressure acts on the inclined surface 61 a defining the pressure chamber 61. as a result,
The plunger barrel 13 is urged by the fuel pressure, and moves upward against the urging force of the coil spring 60.

On the other hand, when the fuel pressure in the fuel pressurizing chamber 15 decreases due to the downward movement of the plunger 17, the fuel pressure in the pressure chamber 61 also decreases. As a result, the plunger barrel 13 moves downward by the urging force of the coil spring 60.

According to the above-described embodiment, since the plunger barrel 13 is elastically supported by the coil spring 60, when the shear stress acting between the plunger 17 and the plunger barrel 13 increases, this coil When the spring 60 is elastically deformed and the plunger barrel 13 moves upward, it is possible to suppress a shock shear stress from acting between the two 13 and 17. Therefore, according to the present embodiment, the same effects as the effects (1) and (2) described in the first embodiment can be achieved.

In addition, according to the present embodiment, the following effects can be further obtained. (5) In other words, by constantly reciprocating the plunger barrel 13 in synchronization with the reciprocating movement of the plunger 17, the sliding speed between the plunger 17 and the plunger barrel 13 can be reliably reduced. 17 can further reduce the amount of wear. As a result, it is possible to more reliably suppress a decrease in the discharge capacity due to abrasion at the sliding portion between the plunger 17 and the plunger barrel 13.

(6) Further, in this embodiment, the fuel pressurizing chamber 1
Since the communication hole 62 of the plunger 17, which forms a part of the passage connecting the fuel cell 5 to the discharge unit 40, is opened on the outer peripheral surface of the plunger 17, fuel flows between the plunger 17 and the plunger barrel 13. It is supplied as lubricating oil, and the sliding resistance between the two 13 and 17 is reduced. As a result, the occurrence of wear and thermal damage in the sliding portion between the plunger 17 and the plunger barrel 13 can be more reliably suppressed, and a decrease in pump efficiency due to an increase in sliding resistance is also suppressed. Will be able to do it.

(7) Further, in this embodiment, the pressure chamber 6
1 and a communication hole 67 for connecting the check valve 44
Is opened to the outer peripheral surface of the plunger barrel 13, so that the fuel is also supplied between the plunger barrel 13 and the pump body 12 as lubricating oil. Therefore, the occurrence of wear in the sliding portion between the plunger barrel 13 and the pump body 12 can also be suppressed, and a decrease in the discharge capacity due to fuel leakage in the sliding portion can be suppressed. Become.

Although the embodiments embodying the present invention have been described above, these embodiments can also be implemented by changing the configuration as described below. In the first embodiment, the rubber ring 26 is provided on the upper end side of the plunger barrel 13, but the rubber ring 26 may be omitted.

In the second embodiment, the rubber rings 26 and 54 are provided on the upper and lower ends of the plunger barrel 13. For example, the rubber rings 26 provided on the upper end of the plunger barrel 13 are used. May be omitted. Further, a spring made of a metal material may be provided instead of the rubber rings 26 and 54.

In the second embodiment, the rubber rings 26, 54 disposed on the upper and lower ends of the plunger barrel 13
May be omitted, and a configuration in which the plunger barrel 13 is elastically supported only by the rubber rings 52 and 53 provided on the outer periphery thereof may be adopted.

In the third embodiment, a part of the passage connecting the fuel pressurizing chamber 15 and the discharge portion 40 (communication hole 62) is opened on the outer peripheral surface of the plunger 17, so that the plunger 17 and the plunger barrel are opened. Although the fuel is supplied as the lubricating oil to the plunger 13, a part of the passage connecting the fuel pressurizing chamber 15 and the supply unit 30 may be opened to the outer peripheral surface of the plunger 17.

In the third embodiment, a passage connecting the fuel pressurizing chamber 15 and the discharge section 40 and a hydraulic pressure supply passage for supplying the oil pressure of the fuel pressurizing chamber 15 to the lower end of the plunger barrel 13 are provided. However, the hydraulic supply passage may be formed separately in the pump body 12 and the plunger barrel 13.

In the third embodiment, the coil spring 60 is provided between the cylindrical portion 29 and the plunger barrel 13, but a rubber ring is used instead of the coil spring 60 as in the first embodiment. You may do so.

In the third embodiment, the outer peripheral surface of the plunger barrel 13 and the inner peripheral surface of the pump body 12 are slid. However, as in the second embodiment, the two members 12, 13 are slid. An elastic member such as rubber may be provided between the elastic members, and the elastic deformation of the elastic member may allow the plunger barrel 13 to incline according to the inclination of the plunger 17.

In the above embodiments, the fuel injection pump 10
Is driven by the cam 24 formed on the camshaft 22, but the fuel injection pump 10 is driven by a cam formed on a crankshaft or a member that rotates in conjunction with the crankshaft. You may do so.

[0061]

According to the first aspect of the present invention, since the plunger barrel is supported by the pump body so as to be movable in the reciprocating direction of the plunger, an impact acting on a sliding portion between the plunger and the plunger barrel is provided. Shear stress is reduced by the plunger barrel moving in the same direction as the plunger, thereby suppressing the occurrence of wear and thermal damage in the sliding portion. Further, since the relative speed between the plunger and the plunger barrel is reduced by the movement of the plunger barrel, the amount of wear can be reduced in this respect as well. As a result, the discharge capacity of the fuel pump can be maintained for a long time, and the durability of the fuel pump can be improved.

In particular, according to the second aspect of the present invention, the plunger is provided with an elastic member interposed between the pump body and the plunger barrel in the reciprocating direction of the plunger and elastically supporting the plunger barrel. The collision between the plunger barrel and the pump body due to the movement of the barrel is reduced. As a result, in addition to the effect of the invention described in claim 1, it is possible to suppress the generation of abnormal noise due to the collision between the plunger barrel and the pump body.

According to the third aspect of the present invention, there is provided an elastic member interposed between the pump body and the plunger barrel in a direction perpendicular to the reciprocating direction of the plunger to elastically support the plunger barrel. Therefore, even if the plunger is inclined, the plunger barrel can also be inclined in accordance with the inclination, so that the contact surface pressure between the two can be suppressed from becoming uneven. As a result, in addition to the effects of the invention described in claim 1 or 2, the occurrence of wear and thermal damage in the sliding portion between the plunger and the plunger barrel can be suppressed more reliably.

Further, in the invention described in claim 4, one end of the plunger barrel located on the same side as the direction of movement of the plunger when pressurizing the fuel in the fuel pressurizing chamber is directed toward the other end. And a fuel pressure supply passage for supplying the fuel pressure of the fuel pressurizing chamber to the vicinity of the other end so as to urge the other end toward the one end. I am preparing for it. Therefore, the plunger barrel always reciprocates in the same direction in synchronization with the reciprocation of the plunger, so that the sliding speed between the plunger and the plunger barrel is surely reduced, and the amount of wear between the two is further reduced. I will be. As a result, in addition to the effect of the invention described in any one of the first to third aspects, it is possible to more reliably suppress a decrease in the discharge capacity due to wear in the sliding portion between the plunger and the plunger barrel. .

Further, according to the invention described in claim 5,
Since at least one of the supply passage for supplying fuel to the fuel pressurizing chamber and the discharge passage for discharging fuel from the fuel pressurizing chamber has an opening on the outer peripheral surface of the plunger,
Fuel is supplied as lubricating oil between the plunger and the plunger barrel, and the sliding resistance between the two is reduced. As a result, in addition to the effect of the invention described in any one of claims 1 to 4, the occurrence of wear and thermal damage in the sliding portion between the plunger and the plunger barrel can be more reliably suppressed, and the sliding resistance can be reduced. , It is also possible to suppress a decrease in pump efficiency due to an increase in the pressure.

[Brief description of the drawings]

FIG. 1 is a sectional view of a fuel injection pump according to a first embodiment.

FIG. 2 is a sectional view of a fuel injection pump according to a second embodiment.

FIG. 3 is a sectional view of a fuel injection pump according to a third embodiment.

FIG. 4 is a sectional view of a conventional fuel injection pump.

FIG. 5 is a sectional view showing a contact state between a plunger and a plunger barrel.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Fuel injection pump, 12 ... Pump body, 13 ... Plunger barrel, 14 ... Mounting part, 15 ... Fuel pressurization chamber, 16
... bolt, 17 ... plunger, 19 ... inner flange, 20
... Cylinder head, 20a ... Mounting hole, 21 ... Lifter, 2
2 camshaft, 23 retainer, 24 cam, 25
... Coil spring, 26 ... Rubber ring, 27 ... Gap,
29 ... Cylinder part, 30 ... Supply part, 31 ... Bolt, 31a ...
Internal hole, 32: check valve, 33: passage, 37: supply pipe, 40: discharge section, 44: check valve, 42: union, 42a: internal hole, 43: discharge pipe, 46: passage,
50, 51: circumferential groove, 52 to 54: rubber ring, 55: gap, 60: coil spring, 61: pressure chamber, 61a ...
Inclined surface, 62: communication hole, 66: passage, 67: communication hole.

Claims (5)

[Claims] 1. A fuel pump comprising: a plunger configured to pressurize fuel in a fuel pressurized chamber formed in a pump body; and a plunger barrel provided in the pump body to support the plunger so as to reciprocate. A fuel pump, wherein the barrel is supported by the pump body so as to be movable in a reciprocating direction of the plunger. 2. The fuel according to claim 1, further comprising an elastic member interposed between the pump body and the plunger barrel in a reciprocating direction of the plunger and elastically supporting the plunger barrel. pump. 3. The apparatus according to claim 1, further comprising an elastic member interposed between said pump body and said plunger barrel in a direction perpendicular to a reciprocating direction of said plunger to elastically support said plunger barrel. Item 3. The fuel pump according to item 1 or 2. 4. An urging device for urging one end of the plunger barrel located on the same side as the movement direction of the plunger when pressurizing the fuel in the fuel pressurizing chamber toward the other end. A member, and a fuel pressure supply passage for supplying a fuel pressure of the fuel pressurizing chamber to the vicinity of the other end so as to urge the other end toward the one end. The fuel pump according to any one of claims 1 to 3, wherein: 5. The fuel supply system according to claim 1, wherein at least one of a supply passage for supplying fuel to the fuel pressurizing chamber and a discharge passage for discharging fuel from the fuel pressurizing chamber has an opening on an outer peripheral surface of the plunger. The fuel pump according to any one of claims 1 to 4, wherein: