JPH11132156A - Fuel pressurising pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent fuel from leaking from a joint part of a pump body with a cylinder block without requiring steep rising of a manufacturing cost or enlarging of an entire pump. SOLUTION: A deformable plate-shaped member 31 equipped with a communicating hole 34 for communicating a cylinder hole 18 with a delivering port 7 is sandwiched and fixed between a cylinder block 12 and a pump body 8. By coating a soft member such as rubber material 33 on the surface of a board 32 made of hard material, the plate-shaped member 31 is formed. The soft member on the board deforms to tightly adhere to micro recessed and projecting parts on the surface of a joint of the cylinder block 12 with the pump body 8. Because the cylinder block 12 or the pump body 8 requires no groove machining, the pump can be manufactured at a low cost and miniaturized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plunger type fuel pressurizing pump used for a fuel injection device of an automobile, and more particularly to a pump body having an intake port and a discharge port, and a cylinder block for accommodating the plunger. The present invention relates to a fuel pressurizing pump formed in a body.

[0002]

2. Description of the Related Art As this kind of fuel pressurizing pump, a pump as disclosed in Japanese Patent Application Laid-Open No. 9-112408 has been conventionally devised.

This fuel pressurizing pump is an axial type plunger pump, in which a swash plate is attached to an end of a drive shaft which rotates by receiving engine power, and a plurality of plungers are provided at positions opposed to the swash plate. A cylinder block is provided for accommodating the cylinder in a freely movable manner. The plunger forms a pump chamber between the cylinder block and the cylinder hole,
The pump is continuously pressed by being pressed by the swash plate. Also, the cylinder block is formed separately from the pump body having the suction port and the discharge port,
It is bolted to the pump body when assembling the pump. Each pump chamber formed by the cylinder hole and the plunger communicates with a discharge port of the pump body via a coupling surface between the cylinder block and the pump body.

In this fuel pressurizing pump, a cylinder block having a cylinder hole is formed separately from a pump body. Therefore, only the cylinder block having a cylinder hole is formed of a material having high wear resistance to form the pump body. It can be made of low cost materials,
Processing of the cylinder hole and other passage holes is facilitated, and the assemblability of components such as the check valve is improved. Therefore,
In this pump, it is possible to manufacture the pump at lower cost than when the cylinder block is formed integrally with the pump body.

[0005]

The fuel pressurizing pump handles low-viscosity fuel such as gasoline and pressurizes the fuel to an extremely high pressure by a plunger. When the cylinder block and the cylinder block are formed separately, it is necessary to completely seal the space between the coupling surfaces, particularly the peripheral area of the communication connection portion between the pump chamber (cylinder hole) and the discharge port.

For this reason, in the conventional fuel pressurizing pump, an annular seal groove is formed on the connecting surface between the pump body and the cylinder block, and a seal ring is interposed in the seal groove, or the pump body and the cylinder are connected to each other. By increasing the processing accuracy of the joint surface of the block, leakage of fuel from the joint between the two is prevented.

However, in any case, the manufacturing cost is increased due to the necessity of groove processing and high-precision finishing processing.
Further, when a seal ring is used, the thickness of the pump body and the cylinder block must be increased in order to secure the depth of the seal groove, and there is a problem that the entire pump becomes large.

Accordingly, the present invention provides a fuel pressurizing pump capable of reliably preventing fuel from leaking from a joint between a pump body and a cylinder block without increasing manufacturing costs or increasing the size of the entire pump. What you want to do.

[0009]

According to a first aspect of the present invention, a cylinder block having a cylinder hole is coupled to a pump body having a suction port and a discharge port. A plunger that moves forward and backward by receiving external power is housed in the cylinder hole, and a pump chamber formed by the cylinder hole and the plunger is connected to a discharge port of the pump body via a coupling surface between the cylinder block and the pump body. In the communicating fuel pressurizing pump, a deformable plate member having at least a communication hole communicating the cylinder hole and the discharge port is sandwiched and fixed between the cylinder block and the pump body. The minute irregularities present on the connecting surfaces of the cylinder block and the pump body are absorbed by the deformation of the plate-like member, and the cylinder block and the pump body come into close contact with the plate-like member, respectively. As a result, leakage of fuel from the joint surface between the cylinder block and the pump body is prevented.

According to a second aspect of the present invention, in the first aspect, the plate-like member is formed by coating a soft member on the surface of a substrate made of a hard member. The minute unevenness of each connecting surface between the cylinder block and the pump body is absorbed by the soft member on the surface, and the damage of the plate-like member due to the tightening load of the cylinder block and the pump body is prevented by the substrate which is a hard member.

According to a third aspect of the present invention, in the first or second aspect, a bead is formed in the plate-like member so as to surround the communication hole. The contact surface pressure in the peripheral area of the communication hole is increased by the bead, and leakage of fuel from the peripheral area of the communication hole is reliably prevented.

According to a fourth aspect of the present invention, in any one of the first to third aspects, the plate member is formed of an elastic body. Due to the elasticity of the elastic body, the plate-shaped member comes into close contact with the coupling surface of the cylinder block and the pump body.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the present invention will be described with reference to FIGS.
A description will be given based on FIG.

In this embodiment, an axial plunger pump is applied as a fuel pressurizing pump 1 according to the present invention. As shown in FIG. 1, a fuel tank 3 is supplied via a motor driven feed pump 2. The sent fuel such as gasoline is adjusted to a predetermined pressure by a low-pressure regulator 50, and then is pressurized to a high pressure by the pressurizing pump 1 and supplied to an injector 4 of a fuel injection device.

Pump housing 5 of fuel pressurizing pump 1
The bearing block 9 is connected to a pump body 8 having a suction port 6 and a discharge port 7 by bolts 10, and a cylinder block 12 is provided in a working chamber 11 formed between the pump body 8 and the bearing block 9. Main components of the pump, such as the pump and the swash plate 13, are accommodated. A drive shaft 14 is fitted into the bearing block 9, and in this state, the drive shaft 14 is rotatably supported via a metal bearing 15. At the end of the drive shaft 14 facing the inside of the working chamber 11, the swash plate 13 whose end surface is inclined at a predetermined angle with respect to the axis is integrally formed. A coupling 16 is provided for coupling with a camshaft (not shown).

The cylinder block 12 is formed of a material having high wear resistance separately from the pump body 8, and is connected to the bottom wall of the pump body 8 by bolts 17. The cylinder block 12 has three cylinder holes 18 formed at equal intervals in the circumferential direction along the axial direction. Each of the cylinder holes 18 has a plunger 20 urged by a spring 19 in the direction of the swash plate 13. It is housed so that it can move forward and backward. Each plunger 20 forms a pump chamber 51 together with the corresponding cylinder hole 18. Each plunger 20 has a hemispherical recess 21 on its top surface.
A shoe 22 whose end surface is in sliding contact with the swash plate 13 is slidably fitted and held in the recess 21. Accordingly, when the swash plate 13 rotates, each plunger 20 is sequentially pressed by the swash plate 13 via the shoe 22 and continuously advances and retreats in cooperation with the spring 19. A ball bearing 23 is interposed between the bottom wall of the bearing block 9 and the swash plate 13 so that a thrust load acting on the swash plate 13 is supported by the bearing block 9 via the ball bearing 23. Has become.

As shown in FIG. 2, the suction port 6 of the pump body 8 and the working chamber 1 are provided in the cylinder block 12.
An introduction passage 24 communicating with the inside of the fuel cell 1 is formed, and the fuel pressure regulated by the low-pressure regulator 50 is introduced into the working chamber 11 through the introduction passage 24.

The cylinder block 12 is formed with three suction passages 25 communicating between the bottom of each cylinder hole 18 (pump body 8 side) and the working chamber 11. An intake check valve 26 that allows only the fuel to flow toward the cylinder hole 18 is provided. Each of the suction passages 25 is, specifically, a through hole 25 a penetrating the cylinder block 12 in the axial direction, and a through hole 25 of the overlapping surface of the cylinder block 12 and the pump body 8.
a suction check chamber 25b formed at a position facing a, and a passage groove 25c formed on the overlapping surface of the pump body 8 of the cylinder block 12 so as to communicate the suction check chamber 25b with the cylinder hole 18. ing.

The pump body 8 is formed with three discharge passages 27 connecting the bottom of each cylinder hole 18 and the discharge port 7. In each of the discharge passages 27, a fuel discharge direction is formed. The discharge check valve 28 which allows only the flow is interposed.

By the way, the cylinder block 12 is not directly connected to the bottom of the pump body 8 and bolted, but a deformable plate-like member 31 is interposed between the cylinder block 12 and the pump body 8. . The plate-shaped member 31 is a hard metal circular substrate 3 having substantially the same diameter as the cylinder block 12.
2 is coated with a rubber material 33, and the rubber material 33 on the surface is brought into close contact with the coupling surfaces 12a, 8a of the cylinder block 12 and the pump body 8. As shown in FIG. 6, the plate member 31 is formed with three discharge-side communication holes 34 that communicate the cylinder holes 18 of the cylinder block 12 with the discharge passages 27 (discharge ports 7) of the pump body 8. In addition, a suction side communication hole 35 that communicates the introduction passage 24 of the cylinder block 12 with the suction port 6 of the pump body 8, a positioning pin insertion hole 36, and a bolt insertion hole 37 are respectively formed.

The discharge side communication holes 34 of the plate-shaped member 31 are formed so as to surround from the suction check chamber 25b to the passage groove 25c and the cylinder hole 18, and the respective discharge side communication holes 34 are formed. 6 and 7, an annular bead 38 as shown in FIGS. 6 and 7 is formed by embossing the circular substrate 32.

Reference numeral 29 denotes an annular sealing member for preventing fuel from leaking from a gap between the drive shaft 14 and the bearing block 9. Reference numeral 30 denotes a stopper for preventing the annular sealing member 29 from coming off. It is a ring.

In the above configuration, when the drive shaft 14 rotates with the start of the engine, the swash plate 13 sequentially presses each plunger 20 via the shoe 22, whereby the plunger 20 continuously pumps. Will do it. That is, when the plunger 20 projects from the cylinder hole 18 by the force of the spring 19, the fuel in the working chamber 11 regulated by the low-pressure regulator 50 opens the suction check valve 26 and is sucked into the pump chamber 51 (cylinder hole 18). When the plunger 20 is pushed into the cylinder hole 18 from this state, the fuel in the pump chamber 31 is pressurized to a high pressure, the discharge check valve 28 is opened, and the fuel is discharged to the discharge port 7.

Here, the fuel pressurized to a high pressure in each pump chamber 51 acts on a portion of the coupling surfaces 12a, 8a of the cylinder block 12 and the pump body 8 extending from the cylinder hole 18 to the suction check chamber 25b. However, since the peripheral area of this portion is securely sealed by the plate-shaped member 31 sandwiched and fixed between the cylinder block 12 and the pump body 8, fuel does not leak from this portion. That is,
Since the surface of the plate member 31 is coated with the rubber material 33, the cylinder block 12 is
When the bolt 17 is coupled to the rubber member 33, the rubber material 33 on the surface of the plate-like member 31 is elastically deformed by receiving the tightening load, and the coupling surfaces 12a, 12a,
8a are adhered so as to fill the minute irregularities. In particular, since the bead 38 is formed annularly in the peripheral region of the discharge-side communication hole 34 of the plate-shaped member 31, the contact surface pressure of the plate-shaped member 31 with respect to the cylinder block 12 and the pump body 8 reduces the discharge-side communication. The height is locally increased in the peripheral region of the hole 34, and leakage of fuel from the peripheral region is reliably prevented. The member for coating the circular substrate 32 of the plate-like member 31 is not limited to the elastic material such as the rubber material 33,
A soft material having no elasticity may be used.
As long as it has elasticity as shown in FIG. 3, it is possible to further increase the adhesion to the cylinder block 12 and the pump body 8 by the elasticity. Further, if the circular substrate 32 is formed of a material having elasticity such as spring steel, the adhesion at the bead 38 can be further improved.

Further, the plate-like member 31 is formed by coating a rubber material 33 on the surface of a circular substrate 32 made of a hard metal, so that the rubber material 33 having a small thickness is hardly plastically deformed.
Therefore, even if a large tightening load is applied by the bolt 17, there is no problem that the rubber material 33 is damaged by the load. Therefore, in the fuel pressurizing pump 1, the reliability of the seal by the plate-shaped member 31 is high, and stable performance can be assured for the shipped product.

In the fuel pressurizing pump 1 of this embodiment, the plate member 31 is simply sandwiched and fixed between the cylinder block 12 and the pump body 8 as described above. Since the leakage of fuel from the surfaces 12a and 8a can be reliably prevented, the coupling surfaces 12a and 8a of the cylinder block 12 and the pump body 8 can be prevented.
In comparison with the case where a seal groove is machined and a seal ring is interposed therein, the machining cost for the cylinder block 12 and the pump body 8 can be kept low, and the machining allowance for machining the seal groove is reduced. The cylinder block 12 and the pump body 8 can be reduced in size because they need not be secured.

The embodiments of the present invention are not limited to those described above. For example, the plate-like member 31 interposed between the cylinder block 12 and the pump body 8 is entirely made of aluminum, copper, or the like. It may be formed of a soft resin such as a soft metal or rubber. Also, the driving method of the plunger may be driven by a cam other than the swash plate.

[0028]

As described above, according to the first aspect of the present invention, a deformable plate-like member having at least a communication hole communicating a cylinder hole and a discharge port is sandwiched and fixed between a cylinder block and a pump body. As a result, the surface of the plate-shaped member is brought into close contact with the connecting surface between the cylinder block and the pump body, so that the fuel does not leak from these connecting surfaces without performing special processing on the connecting surface between the cylinder block and the pump body. Can be reliably prevented. Therefore, it is possible to reliably prevent the fuel from leaking without increasing the manufacturing cost. Also, since the plate-shaped member is merely sandwiched between the cylinder block and the pump body, there is no need to form a groove or the like on the cylinder block or the pump body side,
The size of the cylinder block and the pump body can be reduced accordingly, and the size of the pump as a whole can be reduced.

According to a second aspect of the present invention, in the first aspect of the present invention, the plate-like member is formed by coating a soft member on the surface of a substrate made of a hard member. By using the member, it is possible to achieve both the securing of the sealing property of each connecting surface of the cylinder block and the pump body and the improvement of the durability.

According to a third aspect of the present invention, in the first or second aspect, a bead surrounding the peripheral area of the communication hole is formed in the plate member, so that the contact surface pressure in the peripheral area of the communication hole is reduced. By increasing the bead, it is possible to more reliably prevent the fuel from leaking from the peripheral area of the communication hole.

According to a fourth aspect of the present invention, in any one of the first to third aspects of the present invention, the plate-like member is formed of an elastic body. It is possible to further enhance the adhesion of the plate-shaped member and more reliably prevent leakage of fuel.

[Brief description of the drawings]

FIG. 1 is a sectional view taken along line AA of FIG. 2 showing one embodiment of the present invention.

FIG. 2 is a sectional view of the embodiment, taken along line BB of FIG. 1;

FIG. 3 is a sectional view of the embodiment, taken along the line CC in FIG. 1;

FIG. 4 is a cross-sectional view of the same example taken along the line DD in FIG. 1;

FIG. 5 is a sectional view of the same example taken along line EE of FIG. 3;

FIG. 6 is a plan view showing the embodiment.

FIG. 7 is a sectional view of the embodiment, taken along line FF of FIG. 6;

[Description of Signs] 1 ... Pump for fuel pressurization, 6 ... Suction port, 7 ... Discharge port, 8 ... Pump body, 12 ... Cylinder block, 8a, 12a ... Coupling surface, 18 ... Cylinder hole, 20 ... Plunger, 31 ... Plate-shaped member, 34: discharge side communication hole (communication hole), 38: bead, 51: pump chamber.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Yoshio Okubo 1370 Onna, Atsugi-shi, Kanagawa Prefecture Inside Unisia Gex Co., Ltd. 72) Inventor Hirokazu Akiba 1370 Onna, Atsugi-shi, Kanagawa Prefecture

Claims (4)

[Claims] A cylinder block having a cylinder hole is coupled to a pump body having a suction port and a discharge port, and a plunger which moves forward and backward by receiving external power is accommodated in the cylinder hole. And a plunger, wherein a pump chamber formed by the fuel pressurization pump communicates with a discharge port of the pump body via a coupling surface of the cylinder block and the pump body, and has a communication hole that communicates at least the cylinder hole with the discharge port. A fuel pressurizing pump, wherein a deformable plate-shaped member is sandwiched and fixed between the cylinder block and a pump body. 2. The fuel pressurizing pump according to claim 1, wherein the plate member is formed by coating a soft member on a surface of a substrate made of a hard member. 3. The fuel pressurizing pump according to claim 1, wherein a bead is formed in the plate-like member to surround a peripheral area of the communication hole. 4. The fuel pressurizing pump according to claim 1, wherein the plate member is formed of an elastic body.