JPS6085269A - Fluid pump of piston type - Google Patents

Abstract

PURPOSE:To facilitate work for assembling a piston part, by respectively providing annular retainers in a cylinder part and a rod part and interposing a compression spring between the both retainers. CONSTITUTION:A cylindrical retainer 26 is assembled between a flange part 22b in a rod part 22 and the bottom surface of a piston part 21 by a nut 27 through a gasket 25. Then a compression spring 17 of large contour is interposed between an inward facing flange part 12b formed in the bottom end of a cylinder liner 12 and an outward facing flange part 26b of the retainer 26. In this way, the piston part 21, causing no reaction force of the spring to act on the piston part 21 when it is fitted into the cylinder liner 12, can be easily assembled by only dropping down the piston part 21 into the cylinder liner 12.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a piston-type fluid pump that is installed in a vehicle such as an automobile, and that is driven by an engine or the like and functions as a vacuum pump or the like.

(Prior art) Generally, in this type of piston-type fluid pump, the piston part of the operating piston is slidably inserted in the axial direction into a cylinder part provided inside the housing body, and the pump is attached to one side of the piston part. A rod portion forming a chamber and having the piston portion assembled at one end thereof is engaged with a swinging end portion of a rocker arm that swings due to rotation of a pump drive shaft, and the actuating piston is inserted into the housing body. An interposed compression spring is biased against the pushing force of the rocker arm, and the swinging action of the rocker arm reciprocates the actuating piston in the axial direction to generate negative pressure or positive pressure in the pump chamber. It is composed of

By the way, regarding the conventional piston type fluid pump of this type, there is
As illustrated in No. 9 and shown in FIG. It is interposed between the retainer 3b and the actuating piston 3 is forced toward one end of the rod portion 3c. Therefore, when assembling the piston part 3a of the actuating piston 3 to the cylinder part 2a of the housing body 2, the piston part 3a is attached to one end of the cylinder part 2a while bending the compression spring 1 toward the other end of the rod part 3c. It is assembled by pushing the rocker arm 4 into the interior through the opening and bringing the swinging end 4a of the rocker arm 4 into contact with the seat portion 3d of the rod portion 3c. Therefore, in order to assemble the piston part 3a to the cylinder part 2a, it is necessary to push the piston part 3a parallel to the inner peripheral wall of the cylinder part 2a against the compression spring 1, but this is never possible. It's not easy.

(Object of the Invention) The present invention has been made to solve such problems, and its main purpose is to compress the piston part of the working piston against the cylinder part of the housing body by compressing the piston part of the piston part of the housing body in this type of piston type fluid pump. The purpose is to make it possible to easily assemble the piston part of the working piston to the cylinder part so that it is biased in the same direction as the biasing direction of the spring.

(Structure of the Invention) In order to achieve the above object, the present invention provides the piston type fluid pump described above, in which the cylinder portion 111! Ring retainers were provided on the first side and on the other end of the rod portion of the working piston, and the compression spring was interposed between these retainers to bias the rod portion of the working piston toward the other end side. Particularly noteworthy are its structural features.

(Operations and Effects of the Invention) Accordingly, in the present invention, the rod portion of the actuating piston can be pulled into the housing main body in a state in which the rod portion of the actuating piston is equally urged toward the other end by the compression spring, so that the rod portion of the actuating piston can be The piston part can be inserted into the interior of the cylinder part from the opening at one end thereof without any restriction, and can be inserted into one end of the rod part. Therefore, according to the present invention, the piston part can be easily assembled without requiring much attention, and the work of assembling the piston part can be significantly improved.

(Embodiment) Hereinafter, an embodiment of the present invention will be described based on the drawings. FIG. 1 shows a vacuum pump which is an embodiment of the piston type fluid pump according to the present invention. In this vacuum pump, a housing body 10 is attached to a cylinder head and a head cover (not shown) on the upper side of an engine in a vehicle, and an operating piston 20 is disposed within the housing body lo. Further, a rocker arm 30 is disposed in a space formed by the lower housing 11 of the housing body 10, the cylinder head, and the head cover, and one end of this rocker arm 30 is connected to an overhead camshaft 41 of the engine.
It is in contact with an eccentric cam 42 provided in the.

The operating piston 20 has a disk-shaped piston part 21 and a rod part 22 as main components, and the lower housing 1
The piston part 21 is airtightly and slidably fitted into the cylinder part 12a formed by the cylinder liner 12 press-fitted into the cylinder liner 12, and the lower end of the rod part 22 is slid axially onto the bottom of the lower housing 11. It is assembled within the lower housing 11 by movably supporting it. The operating piston 20 is urged downward in the figure by a second compression spring 17, which will be described later, and its rod portion 22 is supported by a fork portion 31, which is a swinging end portion of a rocker arm 30. The contact portion 32 resiliently contacts the outer periphery of the eccentric cam 42 from its lower part. As a result, a pump chamber R1 is formed on the upper surface side of the piston portion 21 of the working piston 20, and this pump chamber R1 is connected to the suction check valve 1 in the suction chamber R2 provided in the upper housing 13.
4, and is intermittently connected to the atmosphere via a discharge check valve 15 of the piston portion 21.

Therefore, in the working piston 2° in this embodiment, the lower end side of the rod portion 22 is formed into a step-shaped rod shape, and the collar 23 is fitted into the small diameter portion 22a so as to be slidable in the axial direction. There is. The collar 23 has an outward flange portion 23a at its lower end.
A first compression spring 24 having a small diameter is interposed between the outer flange portion 3a and the outward flange portion 22b provided on the rod portion 22. As a result, the collar 23 is attached to the fork portion 3 of the rocker arm 30.
The first compression spring 24 is received by the rocker arm 1 and abuts against the stepped portion 22c of the rod portion 22, and the first compression spring 24 always biases the rocker arm 30 in the counterclockwise direction in the drawing via the collar 23. Further, a cylindrical retainer 26 is connected between the flange portion 22b of the rod portion 22 and the lower surface of the piston portion 21 via a gasket 25.
is assembled with a nut 27. The cylindrical portion 26a of the retainer 26 extends downward by a predetermined length, and an outward flange portion 26b is formed at a portion between its lower ends. On the other hand, an inward flange portion 12b that functions as a retainer is formed at the lower end of the cylinder liner 12 forming the cylinder portion 12a. A second compression spring 17 with a large diameter is interposed. The second compression spring 17 constantly urges the actuating piston 20 downward via the retainer 26 to bring the stepped portion 22C of the rod portion 22 into contact with the collar 23, and the negative pressure in the pump chamber R1 is maintained at a predetermined pressure. When the pressure exceeds this level, it is compressed upward in response to this negative pressure. The filter 16 is made of a porous material such as a wire mesh, and prevents sludge generated in the crankcase and the like and mixed into the engine oil from flowing into the cylinder portion 2a.

The vacuum pump configured in this manner is in the state shown in FIG. 1 when not driven, and when the camshaft 41 rotates in the direction of the arrow due to engine drive, the rocker arm 3
0 repeatedly swings vertically about the support shaft 33 due to the action of the eccentric cam 42, and the working piston 20 moves to the second position.
It is repeatedly slid in the vertical direction by the downward biasing action of the compression spring 17 and the upward pushing action of the rocker arm 3o. During this period, when the working piston 20 moves upward, the suction check valve 14 closes and the discharge check valve 15 opens, and the air in the pump chamber R1 is discharged through the discharge check valve 15. Further, when the operating piston 20 moves downward, negative pressure is generated in the pump chamber R1, and the suction check valve 14
When the discharge check valve 15 opens, the discharge check valve 15 closes, and the negative pressure generated in the pump chamber R1 is applied to a negative pressure actuator such as a brake booster through the suction chamber R2.

By the way, during this time, the negative pressure in the pump chamber R1 increases, and the suction force acting on the piston portion 21 of the working piston 20 becomes second.
When the second compression spring 17 overcomes the biasing force of the compression spring 17, it is compressed upward according to the negative pressure in the pump chamber R1. Therefore, the bottom dead center of the operating piston 20 is at the second
The compression spring 17 moves upward in accordance with the amount of compression, that is, the value of the negative pressure in the pump chamber R1, and accordingly, the stepped portion 22c of the rod portion 22 and the upper end portion of the collar 23 are separated. As a result, when the negative pressure in the pump chamber R1 exceeds a predetermined value, the operation and the force acting on the rocker arm 30 of the stone 20 are reduced. Therefore, wear of each sliding part in the vacuum pump is reduced, and power loss of the engine is reduced.

In this vacuum pump, in order to assemble the working piston 20 into the housing body 10, the cylinder liner 12, the filter 16, the second compression spring 1
The cylinder liner 12 is press-fitted into the lower housing 11 by inserting all the components of the operating piston 20 except for the piston 7 and the piston part 21 into the lower housing 11 from the upper end opening in a temporarily assembled state. Next, the piston part 2
1 is fitted into the inside of the cylinder liner 12 from the upper end opening thereof, and is fitted to the upper end of the rod portion 22, and a nut 27 is screwed onto the upper end of the rod portion 22 and tightened. This completes the assembly of the actuating piston 20, but when the piston part 21 is inserted into the cylinder liner 12, the spring reaction force does not act on the piston part 21 as in the conventional case, so the piston part 21 is simply inserted. Cylinder liner 12
It can be easily assembled (=J) by dropping the piston part 21 into the body. Accordingly, according to this embodiment, it is not necessary to be very careful when assembling the piston part 21, Workability can be significantly improved.In addition, when assembling the piston portion 21 1j, it goes without saying that the inner circumferential wall of the cylinder liner 12 will not be damaged, and the above damage will impair pump performance and the piston ring. Durability is not compromised.

(Modification) FIG. 2 shows a modification of the above embodiment. This modification is formed in the same manner as in the above embodiment except that the cylinder liner 12A and the retainer 12B of the second compression spring 17 are formed from separate members. This retainer 12B is the cylinder liner 12 of the above embodiment.
Like the inward flange portion 12b in , it is configured in an annular plate shape. However, in this modified example,
This is convenient when a material with poor moldability is used as the molding material for the cylinder liner 12A.

In addition, in the above embodiment, an example of a vacuum pump equipped with a pump chamber functioning as a negative pressure chamber was shown, but the present invention can also be applied to a fluid pump such as a fuel pump equipped with a pump chamber functioning as a positive pressure chamber. It can be implemented.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view of a vacuum pump that is an example of a fluid 71 according to the present invention, FIG. 2 is a vertical cross-sectional view of a modified example of the same vacuum pump, and FIG. It is a longitudinal cross-sectional view showing.Explanation of symbols 10...Housing main body, 12.12A...Cylinder liner, 12B, 12b...Retainer, 17...
Second compression spring, 20... Operating piston, 21.
...Biss) N part, 22...Rod part, 26...Retail arm, 30...Port/linker arm, R1...Pump chamber. Applicant Toyota Motor Corporation (and 1 other person) Agent Patent attorney Teru Hase −

Claims (1)

[Claims] A lot in which the piston part of the operating piston is slidably inserted in the cylinder part provided inside the housing body in the axial direction to form a pump chamber on one side of the piston part, and the piston part is assembled at one end. a swinging end of a rocker arm that swings due to rotation of a pump drive shaft, and the actuating piston is biased against the pushing force of the rocker arm by a compression spring interposed in the housing main body. In the piston type fluid pump, the actuating piston is reciprocated in the axial direction by the rocking action of the rocker arm to generate negative pressure or positive pressure in the pump chamber, the curved end of the cylinder portion of the housing body Annular retainers are provided on one side and the other end of the rod portion of the actuating piston, and the compression spring is interposed between these retainers to bias the rod portion of the actuating piston toward the other end. Piston type fluid pump.