JP2536033Y2 - Piston type fluid pump - Google Patents

Description

[Detailed description of the invention]

[0001]

[Industrial application field] The present invention is installed in a vehicle,
The present invention relates to a piston type fluid pump that is driven by an engine or the like and functions as a vacuum pump or the like.

[0002]

2. Description of the Related Art As this type of pump, there is a vacuum pump used for a brake booster of a diesel engine.

This vacuum pump has an upper pump chamber and a lower pump chamber formed above and below a working piston, and a seal member fitted in an annular groove provided on the outer periphery of the piston is provided between the piston and the cylinder. Functions as a sliding part. Then, a roller provided at one end of the rod of the piston is driven by a cam linked to the engine so that the pump is driven by the vehicle engine, and the piston moves up and down.

Further, the rod has a structure in which the rod slides up and down in the rod seal, and a small amount of oil mist is sucked into the lower chamber of the pump through a small gap between the rod and the rod seal opened inside the engine. Had a structure.

[0005]

[Problems to be Solved by the Invention] In the above conventional technology,
Only a small amount of oil mist is sucked into the lower chamber of the pump from the minute gap between the rod and the rod seal. Therefore, when the pump is operated in a high-temperature atmosphere and the air introduced into the pump chamber is exhausted, a small amount of oil accumulated in the pump chamber is removed by the exhaust, and the piston sliding portion becomes poorly lubricated, and the piston ring Wear and cylinder seizure occur.

In addition, the sealability of the piston sliding portion is reduced due to the roughened surface of the piston ring and the sliding surface of the cylinder and the wear of the piston ring, and the pump performance is reduced due to the leakage of the seal.

In addition, the heat generated by sliding increases due to the surface roughness of the sliding surface, the volume of the piston, the O-ring and the like expands, and the surface pressure between the cylinder and the cylinder increases, so that the sliding resistance further increases. Creates a vicious cycle.

[0008] The increased sliding resistance between the piston and the cylinder causes abnormal wear of the piston sliding portion, increases the acting force of the contact portion between the roller and the cam, and the bearing load of the roller and the cam. There has been a problem that the contact portion between the roller and the cam and the sliding portions of these bearings are abnormally worn.

[0009] Therefore, the present invention is to reduce the operating vacuum pressure.
Eliminates poor lubrication of piston sliding parts without lowering
The purpose is to make it.

[0010]

To achieve the above object, a piston type fluid pump according to the present invention comprises a piston rod.
Oil passage in the inner periphery of the seal ring (12)
(12a) and the outer periphery of the piston (6)
Smell with elastic O-ring (8) fitted in groove
And the piston with the piston sliding part and the O-ring (8)
To reduce the interference (5a, 7a) at the bottom of the
And the O-ring (8) and the cylinder (5)
Flexible piston ring made of Teflon between (9)
Are interposed so as to fit on the open side of the piston outer peripheral groove .

[0011]

With the operation of the piston, lubricating oil flows from the oil supply source through the oil passage into one of the pump chambers, and the oil flowing into the one pump chamber lubricates the piston sliding portion with reduced interference. At the same time, the oil flows into and diffuses into the other pump chamber, causing the lubricating oil to adhere to the entire surface of the piston sliding portion.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the embodiments of FIGS. 1, 2 (a) and 2 (b), reference numeral 1 denotes a vacuum pump, which comprises a lower casing 2 and an upper casing 3, and a lower portion of the lower casing 2 is attached to a cylinder head cover 4 of an engine. Fixed.

Reference numeral 5 denotes a cylinder fixed to the lower casing 2, and 6 denotes a piston which moves up and down in the cylinder 5. An O-ring 8 and a Teflon piston ring 9 are provided in a substantially annular groove 7 provided on the outer periphery thereof. Mated. O-ring 8
Presses the piston ring 9 against the inner surface of the cylinder 5 with its elasticity and absorbs a dimensional change of the piston ring 9 due to a temperature change.

The bottom surface of the groove 7 of the piston 6 has a substantially circular shape as a whole, and has notches 7a at three circumferential positions.
The notch 7a functions as an interference reducing portion. 10
Is a rod, which is vertically slidably supported by a bearing 11 provided on the lower casing 2, and the upper end of which is a piston 6.
It is fixed in the center of.

Reference numeral 13 denotes an O-ring provided on the lower casing 2 so as to be fitted to the rod 10.
Absorbs dimensional changes in Reference numeral 12a denotes oil passages provided at four locations on the inner circumference of the seal ring 12 on the circumference.

Reference numerals 14 and 15 denote a pump upper chamber and a pump lower chamber formed above and below the piston 6, respectively. A pipe 16 fixed to the lower casing 2 communicates with a brake booster (not shown).

Reference numerals 17 and 18 denote suction valves which are disposed between the pipe 16 and the upper pump chamber 14 and between the pipe 16 and the lower pump chamber 15, respectively. Reference numerals 19 and 20 denote discharge valves, and the upper pump chamber 14 and the lower pump chamber 15 communicate with the space in the head cover 4 via the discharge valves 19 and 20, respectively.

Reference numeral 21 denotes a pin fixed to the lower end of the rod 10, reference numeral 22 denotes a small-diameter roller rotatably fitted to the pin 21, and reference numeral 23 denotes a large-diameter roller rotatably fitted to the roller 22. The roller 23 comes into contact with an eccentric cam 25 formed on a camshaft 24 of the engine.

26 is a flange formed on the rod 10,
Reference numeral 27 denotes a compression spring disposed between the flange 26 and the lower casing 2. The compression spring 27 urges the rod 10 downward to press the roller 23 against the cam 25.

Since the lubricating oil is forcibly ejected to the contact portion between the roller 23 and the cam 25 by a well-known mechanism, the inside of the head cover 4 is filled with oil mist, and the space between the outer periphery of the flange 26 and the head cover 4 is formed. From spring 27
After that, the oil is also diffused to the vicinity 28 of the lower end of the bearing 11, and this part 28 serves as an oil supply source to the bearing 11.

In the above embodiment, the cam 2 is linked with the engine.
5 rotates, and the rod 10 and the piston 6 move up and down via the roller 23, so that the vacuum pump 1 operates.
When the piston 6 rises, the air in the upper pump chamber 14 is discharged to the space in the head cover 4 via the discharge valve 19, and the air from the brake booster (not shown) passes through the pipe 16 and the suction valve 18 to lower the pump chamber. Inhaled to 15.

At this time, the oil mist of the oil supply source 28 is sucked into the pump lower chamber 15 through the gap between the bearing 11 and the rod 10 and the oil passage 12a by the negative pressure of the pump lower chamber 15 suction, and It diffuses into the chamber 15.

By repeating the reciprocating motion, the oil mist sufficiently flows into the lower pump chamber 15 and adheres to the sliding surface between the piston ring 9 and the cylinder 5 to maintain a good sliding state.

When the piston 6 is lowered, the pump booster chamber 14 passes through the pipe 16 and the suction valve 17 from the brake booster.
Air is sucked in, and the air in the pump lower chamber 15 is discharged. At this time, the lubricating oil adhering to the vicinity of the cylinder 5 and the piston ring 9 on the side of the pump lower chamber 15 reduces the pressing force on the inner surface of the cylinder 5 by the bottom cutout (interference reduction portion) 7a of the groove 7 of the piston 6. Through the weak part, the negative pressure of the upper pump chamber 14 causes the lower pump chamber 15 to
4 and diffuses into the entire upper surface of the pump chamber 14.

By repeating the reciprocating motion, the oil mist sufficiently flows into the upper pump chamber 14, adheres to the entire sliding surface of the piston ring 9 and the cylinder 5, and maintains a good sliding state. FIG. 2B and FIG.
It is extremely drawn, and is actually almost circular. So
Therefore, the notch is not shown in FIG. Therefore
Notches (5a) and (7a) are elastic O-rings when assembled.
(8) Teflon piston ring with flexibility
(9) is in close contact with the cylinder.
Can be between ton rings.

In the embodiment shown in FIGS. 2C and 2D, oil passages 12a are formed at four locations on the inner periphery of the seal ring 12 .

Further, the cylinder 5 having the notch 5a and the piston 6 having the notch 7a may be used together. Further, instead of providing the notch 5a of the cylinder 5 and the notch 7a of the groove 7 of the piston 6, the thickness of the O-ring 8 is partially reduced to about three places on the circumference to reduce the interference. Alternatively, the substantial thickness of the piston ring 9 may be partially reduced (for example, at three locations on the circumference) to function as a reduced interference portion.

Although the above-described embodiment is a backward-acting piston type fluid pump, similar effects can be obtained with a single-acting piston type fluid pump.

[0029]

[Effect of the Invention] As described above, the piston type fluid pump of the present invention reduces the interference in the piston sliding portion and the O-ring groove bottom.
Part, the lubricating oil is affected by the pressure difference between the upper and lower chambers of the pump.
The flexible piston ring deforms and the O-ring
Is contracted, so that the inner circumferential surface of the cylinder and the outer
Weak part of the pressing force between the peripheral surface, that is, squeezing
Through the reduced portion to prevent lubrication failure.
The oil is supplied to the upper and lower chambers as an oil mist. Again
When the lubricating oil passes, the reduced interference portion is
Piston compared to the gap between the outer cylinder and the piston ring
The deformation of the ring and the shrinkage of the O-ring
The gap between the pump upper and lower chambers is not extremely large,
It is possible to minimize the amount of air leakage including luminous mist.
And there is almost no reduction in vacuum pressure.

[0030]

[0031]

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an embodiment of the present invention.

FIG. 2A is an enlarged longitudinal sectional view of a main part of the embodiment of FIG. 1,
(B) is an AA sectional view of the piston of FIG. 1, (c) is an enlarged vertical sectional view of a main part of another embodiment, and (d) is a transverse sectional view of the seal ring of the embodiment of (c).

FIG. 3 is a cross-sectional view of a cylinder according to another embodiment of the present invention, corresponding to a cross section taken along line AA of FIG. 1;

[Explanation of symbols]

 Reference Signs List 5 Cylinder 6 Piston 5a, 7a Reduced interference (notched portion) 14 Upper pump chamber 15 Lower pump chamber 12 Seal ring 12a Oil passage 28 Oil supply source

Continuation of the front page (72) Inventor Kazuya Ando 1-1-1 Kyowa-cho, Obu City, Aichi Prefecture Inside Aisan Industry Co., Ltd. (56) References JP-A-59-206685 (JP, A) 12987 (JP, U) Jikken 43-18930 (JP, Y1)

Claims (1)

(57) [Scope of request for utility model registration] 1. A seal ring fitted to a piston rod.
An oil passage (12a) is formed on the inner periphery of (12).
In addition, O-phosphorus having elasticity is provided on the outer peripheral groove of the piston (6).
(8), the piston sliding portion and the O-ring (8)
Provision of reduced interference (5a, 7a) at the bottom of the outer circumferential groove
And Teflon between the O-ring (8) and the cylinder (5).
Flexible piston ring (9) made of stainless steel
A piston type fluid pump interposed so as to fit on an open side of a groove .