JPH08319950A - Piston type fluid pump - Google Patents

Abstract

PURPOSE: To prevent wear of two members due to the occurrence of a slide between a large roller and a disc cam through the generation of a rotation force at a compression spring during vertical movement of a piston rod, to improve reliability of a pump, and to provide an increased life. CONSTITUTION: A protrusion 20a formed on the outer periphery of a disc cam 20 is engaged with a recessed groove 18a formed in the outer periphery of a large roller 18 to suppress rotation of a piston rod 10 by a rotation force during compression and expansion of a compression coil spring 22.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piston type fluid pump mounted on a vehicle such as an automobile and driven by an engine or the like to function as a vacuum pump or the like.

[0002]

2. Description of the Related Art As a pump of this type, there is a vacuum pump used for a brake booster of a diesel engine (for example, Japanese Patent Laid-Open No. 5-106556).

This vacuum pump has a pump upper chamber and a pump lower chamber formed above and below the working piston, and a seal member fitted in an annular groove provided on the outer circumference of the piston is provided between the piston and the cylinder. Functions as a sliding part.

As the pump is driven by the vehicle engine, a roller provided at one end of the rod of the piston is driven by a disc cam which is interlocked with the engine, and the working piston moves up and down.

A compression coil spring is provided to urge the piston rod downward to press the roller against the outer peripheral cam surface of the disc cam so that the piston rod can move up and down following the rotation of the disc cam. There is.

The vacuum pump described in Japanese Patent Application Laid-Open No. 5-106556 is proposed by the applicant of the present application, and the applicant has since produced a vacuum pump having a structure shown in FIGS.

The structure of the vacuum pump shown in FIGS. 3 to 6 is basically the same as the structure of the vacuum pump described in the above-mentioned Japanese Patent Application Laid-Open No. 5-106556, but communicates with the upper chamber of the pump and the lower chamber of the pump. The suction valve and the discharge valve are not shown.

In these drawings, reference numeral 1 denotes a vacuum pump, which includes a lower casing 2 and an upper casing 3, and is fixed to a cylinder head cover 4 of an engine at a lower portion of the lower casing 2. Reference numeral 5 is a screw that fastens both casings.

Reference numeral 6 is a cylindrical cylinder fixed to the lower casing 2, 7 is a piston which moves up and down in the cylinder 6, and an O-ring 8 and a Teflon piston ring 9 are fitted in an annular groove provided on the outer periphery thereof. ing.

Reference numeral 10 denotes a piston rod, which is axially slidably supported by a bearing 11 provided in the lower casing 2, and the upper end thereof is fixed to the center of the piston 7. 1
Reference numeral 2 denotes a Teflon seal ring provided in the lower casing 2 so as to be fitted into the piston rod 10, and has oil passages formed by small cutouts at four inner circumferences thereof.

Reference numeral 13 denotes an O provided around the seal ring 12.
The ring presses the seal ring 12 against the outer periphery of the piston rod 10 by its elasticity. Reference numerals 14 and 15 denote a pump upper chamber and a pump lower chamber formed above and below the piston 7, respectively, and the pump upper chamber 14 is connected to a brake booster via an intake valve (not shown) and a discharge valve (not shown). It communicates with the space inside the head cover 4.

The pump lower chamber 15 also communicates with the brake booster via another suction valve not shown and with the space inside the cylinder head cover 4 via another discharge valve not shown.

Reference numeral 16 is a pin fixed to the lower end of the piston rod 10, 17 is a small-diameter roller rotatably fitted to the pin 16, and 18 is a large-diameter roller externally fitted to the small-diameter roller 17. The diameter roller 18 is the camshaft 1 of the engine.
It is in contact with the outer peripheral cam surface of the disk cam 20 formed in 9. Reference numeral 19a indicates the axis of the camshaft 19.

Reference numeral 21 is a flange formed near the lower end of the piston rod 10, and 22A and 22B are compression coil springs mounted between the lower casing 2 and the flange 21. The radial roller 18 is pressed against the disc cam 20.

Reference numeral 23 is a detent pin whose upper portion is press-fitted and fixed to the lower casing 2. The lower end extends below the flange 21, and the notch 2 provided on the outer periphery of the flange 21.
1a, piston rod 10 and flange 2
The angular position (phase) of 1 is regulated so as not to unnecessarily shift.

The lower end opening of the bearing 11 and the outer periphery of the large-diameter roller 18 are supplied with lubricating oil which is pumped from a cylinder head (not shown) and discharged from an oil nozzle to be supplied to the sliding portion inside the pump and the pump drive. Lubricate the large-diameter roller 18 as a part.

[0017]

SUMMARY OF THE INVENTION In the above conventional technique,
Lower casing 2 and flange 2 of piston rod 10
Compression coil springs 22A, 22 mounted between
The piston rod 10 is urged downward by B to press the large diameter roller 18 against the outer peripheral cam surface of the disc cam 20, and
When the disc cam 20 is driven by the engine to rotate in one direction, the large-diameter roller 18 as a pump driving unit resists the compression coil springs 22A and 22B and the piston rod 10 is rotated.
And the piston 7 is moved up and down to operate the pump.

Therefore, as the piston rod 10 moves up and down, the compression coil springs 22A and 22B are compressed.
Extend, and each time, both compression coil springs 22A, 22
B is rolled in or unrolled to generate a rotational force, and the flange 21 reciprocally rotates integrally with the piston rod 10 as shown by arrows B and C in FIGS.

Since the piston rod 10 moves up and down and reciprocally rotates in this manner, the large-diameter roller 18 is aligned with the disc cam 20 about the axis of the piston rod 10, as shown in FIG. The phenomenon of reciprocating rotation relatively occurs around.

This relative reciprocal rotation causes a sliding component between the outer peripheral cam surface of the disc cam 20 and the large diameter roller 18,
Originally, the large-diameter roller 18 is not only moved up and down while rolling while being driven by the outer peripheral cam surface of the disc cam 20, but the wear of the large-diameter roller 18 and the disc cam 20 due to a sliding component (sliding) is vacuumed. There is a problem that the performance of the pump is deteriorated and the life of the pump is shortened.

Therefore, an object of the present invention is to solve the above problems and provide a highly reliable piston type fluid pump.

[0022]

In order to achieve the above object, a piston type fluid pump according to claim 1 has a large diameter roller (18) provided on a piston rod (10) and a disc cam (2).
0) is provided with a compression coil spring (22) for urging the piston rod (10) in one direction so that the large diameter roller (18) is rotated by rotation of the disc cam (20).
In a piston type fluid pump that drives a piston rod (10) to reciprocate in the axial direction, a large diameter roller (1
8) an annular groove (18a, 18b) or a ridge is provided on the outer circumference of the disk cam (20), and a ridge (20) engaging with the groove (18a, 18b) or the ridge on the outer circumference of the disc cam (20).
a, 20b) or a groove is provided.

In the present invention, the concave grooves (18a, 18b) or ridges provided on the outer circumference of the large diameter roller (18) and the ridges (20a, 20b) or dents provided on the outer circumference of the disc cam (20). The groove engages with the rotation surface of the large-diameter roller (18),
The rotating surface of the disc cam (20) is held in parallel, and the piston rod (1) is generated by the rotating force of the compression coil spring (22) generated when the piston rod (10) reciprocates.
Rotation around the axis 0) is suppressed.

According to a second aspect of the present invention, in the piston type fluid pump according to the first aspect, the concave groove (18a) has a valley shape having a triangular cross section, and the ridge (20a) engaging therewith has a mountain shape having a triangular cross section. It is characterized by being.

According to the present invention, in addition to the action of the piston type fluid pump according to the first aspect, the engagement position of the concave groove (18a) and the ridge (20a) at the time of assembly becomes easy.

[0026]

1 (a) and 1 (b) show a first embodiment of the present invention.
It is sectional drawing which cut | disconnected the same cut surface as the said FIG.

In the figure, the parts denoted by the same reference numerals as those in the prior art shown in FIGS. 3 to 6 perform the same functions, and therefore the description thereof may be omitted. In the figure, reference numeral 22 is the only compression coil spring for urging the piston rod 10 downward, and corresponds to the two compression coil springs 22A and 22B in the prior art.

Reference numeral 24 is an intake valve provided in a passage communicating between the pump upper chamber 14 and a vehicle brake booster (not shown), and 25 is the pump lower chamber 15 and the cylinder head cover 4.
It is a discharge valve provided in a passage that communicates the inner space. In addition,
Another suction valve (not shown) communicates with the pump lower chamber 15, and another discharge valve (not shown) communicates with the pump upper chamber, but these valves are not shown.

Reference numeral 18a is an annular groove provided on the outer periphery of the large-diameter roller 18 and is formed in a valley shape having a triangular cross section. 20a
Is a convex strip formed on the outer periphery of the disc cam 20 and having a triangular cross section, and engages with the concave groove 18a to determine the relative position of the large diameter roller 18 and the disc cam 20 in the horizontal direction in the drawing. Hold.

In this embodiment, the groove 18a and the ridge 20a are formed.
Since the cross sections of and are triangular and mountain-shaped to engage with each other, when the pump 1 is mounted on the cylinder head cover 4 of the engine, the positioning of the engagement between the groove 18a and the ridge 20a is easy and the assembling work is performed. Can be done easily.

Instead of the above embodiment, the large diameter roller 1
A ridge may be provided on the outer periphery of 8 and a groove may be provided on the outer periphery of the disc cam 20 to engage both. FIG. 2 shows the essential part of the second embodiment of the present invention. A groove 18b having a rectangular cross section is provided on the outer circumference of the large diameter roller 18, and a ridge 20b having a rectangular cross section is provided on the outer circumference of the disc cam 20. Both are engaged.

[0032]

Since the piston type fluid pump of the present invention is constructed as described above, the engaging groove and ridge regulate the relative movement of the large diameter roller and the disc cam in the axial direction. Since the positional relationship is determined, even if the compression coil spring generates a rotational force when the piston rod reciprocates, the piston rod does not rotate by this rotational force. Therefore, the large-diameter roller and the disk cam do not slip, and the large-diameter roller ideally rolls.

Therefore, the wear of the large diameter roller and the disc cam is reduced, the reliability of the pump is improved, and the durability is extended.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of a piston type fluid pump according to the first embodiment of the present invention, and FIG. 1 (b) is an enlarged view of a main part indicated by a symbol B in FIG. 1 (a).

FIG. 2 is an enlarged vertical cross-sectional view of essential parts of a second embodiment of the present invention.

FIG. 3 is a vertical sectional view of a conventional technique.

4 is a cross-sectional view taken along the line AA showing a part of the conventional technique of FIG.

5 is a bottom view of the prior art of FIG.

FIG. 6 is a bottom view of FIG. 3 for explaining the relationship with the disc cam when the piston rod rotates.

[Explanation of symbols]

 10 piston rod 18 large diameter roller 18a, 18b concave groove 20 disk cam 22a, 22b convex line 22 compression coil spring

Claims (2)

[Claims] 1. A large-diameter roller provided on a piston rod is provided with a compression coil spring for urging the piston rod in one direction so that the large-diameter roller presses and abuts on the disc cam, and the large-diameter roller is driven by rotation of the disc cam. In a piston type fluid pump that reciprocates the piston rod in the axial direction, an annular groove or ridge is provided on the outer circumference of the large diameter roller, and the groove or ridge is engaged on the outer circumference of the disc cam. A piston type fluid pump having a ridge or a groove. 2. The piston type fluid pump according to claim 1, wherein the concave groove has a valley shape having a triangular cross section, and the convex strip engaging with the groove has a mountain shape having a triangular cross section.