JPH07217535A - Piston type fluid pump - Google Patents

Abstract

PURPOSE:To secure the compression quantity of a sealing O-ring between an upper casing and a lower casing so as to prevent the lowering of performance as a vacuum pump while being lightweight, and eliminate a gap between the upper casing and the flange part of the lower casing so as to heighten ultimate vacuum performance and simplify the fastening of both casings. CONSTITUTION:An upper casing 3 is compression-molded out of a metal sheet so as to form a hanging part at the outer periphery of the upper casing 3. The hanging part is provided with plural holes 31 being spaced circumferentially. The upper casing 3 is fitted to the flange part 50 of a lower casing, and the hanging part 32 below the hole 31 is plastically deformed in the center direction to fasten both casings. The compression quantity of an O-ring 51 is secured, and the upper casing 3 adheres closely to the upper face of the flange part 50.

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.

[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 (for example, Japanese Patent Laid-Open No. 4-134678).

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. A roller provided at one end of the rod of the piston is driven by a cam interlocking with the engine so that the pump is driven by the vehicle engine, and the working piston moves up and down.

The cylinder is fixed to the lower casing,
An O-ring for sealing is sandwiched between a flange portion on the outer periphery of the upper portion of the lower casing, and an upper casing is fastened with screws from above.

The upper part of the pump upper chamber is separated from the atmosphere by an upper casing, and the lower part of the pump lower chamber is partitioned by a lower casing. Further, the upper casing is composed of a substantially flat metal casing and has a thickness that does not deform so that it can be securely fastened with a plurality of screws. Further, the outer shapes of the upper casing and the flange portion of the lower casing were not circular but complex non-circular in plan view.

Furthermore, as another conventional technique, the actual exploitation Sho 63
There is a fuel pump disclosed in Japanese Patent Publication No. 162979. In this fuel pump, a diaphragm is sandwiched around the upper outer peripheral edge of the lower casing, and the outer peripheral edge of the upper casing is curled all around and fastened.

[0007]

In the former one of the above-mentioned conventional techniques, not only the mass of the entire pump is increased because the thickness of the upper casing is large, but also it is necessary to tap the lower casing for a plurality of taps. Therefore, there is a problem that the processing cost of the parts is high. or,
There is also a problem in that it is necessary to screw a plurality of screws to fasten the upper casing to the lower casing, which increases the number of assembling steps.

Therefore, when the upper casing is coupled to the lower casing of the piston type fluid pump in the fastening structure used in the latter of the prior art to solve the above problems, the outer shape of the flange portion of the lower casing is changed. Since it is a non-circular complicated shape, by curling the entire circumference of the upper casing to the back surface (lower surface) of the flange portion of the lower casing, an uneven gap is generated between the upper surface of the flange portion and the upper casing. .

Therefore, there is a problem in that the compression amount of the sealing O-ring cannot be ensured and a sealing failure occurs. Further, the volume of the upper chamber of the pump increases in accordance with the gap between the upper casing and the lower casing, which causes a problem that ultimate vacuum performance as the vacuum pump deteriorates. Further, a jig or a device for curling the entire circumference of the irregular shaped upper casing around the irregular shaped flange becomes oversized, which causes a problem of increased cost.

Therefore, an object of the present invention is to provide a piston type fluid pump which can solve these problems.

[0011]

In order to achieve the above object, a piston type fluid pump according to a first aspect of the present invention is sandwiched between a piston that moves up and down between an upper casing and a lower casing, and both casings. In a vacuum pump having a sealing O-ring, an upper casing press-molded into a cup shape having a hanging portion on the outer periphery and having a plurality of holes (31) provided at intervals in the circumferential direction at the hanging portion on the outer periphery. (3) and the lower surface of the flange portion (50) is closer to the center of the lower casing (2).
0) A lower casing (2) formed in a taper shape away from the upper surface is provided, and the upper casing (3) is fitted to the flange portion (50) of the lower casing (2),
Among the hanging parts of the upper casing (3), the holes (3
Both casings (3) by plastically deforming the portion (32) located under 1) toward the center of the upper casing (3).
It is characterized in that (2) is concluded.

A piston-type fluid pump according to a second aspect of the present invention is a vacuum pump having a piston that moves up and down between an upper casing and a lower casing, and a sealing O-ring sandwiched between the casings. A plurality of holes (31A) are formed in a cup shape having a portion and are provided in the hanging portion of the outer periphery at intervals in the circumferential direction, and the lower surface of the hole is inclined with respect to the circumferential direction of the outer periphery. An upper casing (3A) provided with an inclined surface (34A) is provided, and the upper casing (3A) is fitted to the flange portion (50A) of the lower casing (2),
Among the hanging parts of the upper casing (3A), the holes (3
It is characterized in that the portion (32A) located under 1A) is plastically deformed toward the center of the upper casing (3A) to fasten both casings (3A) (2).

A piston type fluid pump according to a third aspect of the present invention is a vacuum pump having a piston that moves up and down between an upper casing and a lower casing, and a sealing O-ring sandwiched between the casings. The upper casing (3A) according to claim 2 and the lower casing (2) according to claim 1 are provided, and the upper casing (3A) is fitted into the flange portion (50A) of the lower casing (2), 3A) a portion (32) located below the hole (31A) in the hanging portion.
It is characterized in that both casings (3A) and (2) are fastened by plastically deforming (A) toward the center of the upper casing (3A).

[0014]

[Function] The upper casing is fitted to the flange portion of the lower casing, and among the hanging parts of the upper casing,
By plastically deforming the portion located below the hole toward the center of the upper casing, the inner surfaces of the lower casing facing each other are attracted and abutted against the upper surface of the flange portion of the lower casing.

In this way, both casings are fastened together even if they are non-circular irregular shapes, and the compression amount of the sealing O-ring is secured. Further, since the outer peripheral hanging portion is formed in the upper casing, rigidity can be easily obtained even when the upper casing is press-molded with a thin plate, and the weight can be reduced accordingly.

Further, the device / jig for plastically deforming the upper casing to fasten both casings is simpler than the above-mentioned case where the entire circumference is curled, and the man-hours are short.

[0017]

The first embodiment shown in FIGS. 1 to 6 corresponds to claim 1. 1 is a vacuum pump, lower casing 2
And an upper casing 3 fastened to the lower casing 2, and fixed to a cylinder head cover 4 of the engine at a lower portion of the lower casing 2.

Reference numeral 5 is a cylinder fixed to the lower casing 2, 6 is a piston which moves up and down in the cylinder 5, and an O-ring 8 and a Teflon piston ring 9 are fitted in an annular groove 7 provided on the outer periphery thereof. There is. The O-ring 8 presses the piston ring 9 against the inner peripheral surface of the cylinder 5 by its elasticity and absorbs the dimensional change of the piston ring 9 due to the temperature change.

Reference numeral 10 denotes a piston rod, which is axially slidably supported by a bearing 11 provided on the lower casing 2, and the upper end thereof is fixed to the center of the piston 6. 1
Reference numeral 2 is a Teflon seal ring provided in the lower casing 2 so as to be fitted to the rod 10, and oil passages 12a are formed 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 circumference of the piston rod 10 by its elasticity and absorbs the dimensional change of the seal ring 12 due to the temperature change.

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

Reference numeral 17 denotes a suction valve, which is arranged between the pipe 16 and the pump upper chamber 14. Further, another suction valve (not shown) is arranged between the pipe 16 and the pump lower chamber 15. The pump upper chamber 14 and the pump lower chamber 15 communicate with the space inside the head cover 4 via the discharge valves 19 and 20, respectively.

Reference numeral 21 is a pin fixed to the lower end of the piston rod 10, 22 is a small-diameter roller rotatably fitted to the pin 21, and 23 is a large-diameter roller fitted to the outer periphery of the small-diameter roller 22. Reference numeral 23 is in contact with a cam 25 formed on the cam shaft of the engine.

Reference numeral 26 is a flange formed near the lower end of the piston rod 10, and 27 is a compression spring disposed between the flange 26 and the lower casing 2. The compression spring 26 urges the piston rod 10 downward to move the roller 23. It is pressed against the cam 25.

The roller 23 thus constructed functions as a pump drive unit that follows the cam 25. 24 is a bearing opening located below the bearing 11, 28 is a flange 2
6 is a communication hole. Reference numeral 29 denotes an oil supply means, which has a bearing opening 24 and oil nozzles 29a and 29b for supplying lubricating oil to the outer peripheral surface of the roller 23, which is a pump drive section.

Reference numeral 40 denotes a rod-shaped detent pin fixed to the lower casing 2 by press fitting and mounted so as to descend downward from the lower casing 2. The lower end of the pin 40 is an outer peripheral engaging portion 26a of the flange 26 of the piston rod 10. Is loosely fitted into.

A sliding portion between the engaging portion 26a and the rotation preventing pin 40, that is, the piston rod 10 and the rotation preventing pin 40.
The sliding portions of and are arranged in the radial direction of the cam 25, as is apparent from FIGS. 1 and 6.

Oil nozzle 29 as oil supply means
Lubricating oil ejected from a is the communication hole 2 of the flange 26.
8 to reach the bearing opening 24 directly and further to the bearing 1
1 and the piston rod 10 pass through the oil passage 12
It is sucked into the pump lower chamber 15 via a.

Lubricating oil ejected from the oil nozzle 29b and supplied to the roller 23, which is a pump drive section, adheres to the cam 25, and is scattered by the centrifugal force of the cam 25 so that the engagement section 26a and the detent pin 40 are separated. Lubricate the sliding parts.

The upper casing 3 is formed by pressing a thin metal plate into a cup shape having a hanging portion on the outer periphery,
A plurality of holes 31 are provided in the hanging portion on the outer circumference at intervals in the circumferential direction. Reference numeral 32 denotes a portion of the hanging portion of the upper casing 3 located below the hole 31.

Reference numeral 50 denotes a flange portion formed on the outer periphery of the upper portion of the lower casing 2, and the lower surface of the flange portion 50 is closer to the center of the lower casing 2 (that is, the rod 10).
It is formed in a taper shape that is farther from the upper surface of the flange portion 50.

51 is a flange portion 50 of the lower casing.
The O-ring fitted in the groove provided on the upper surface of the
1 is inserted into the groove on the upper surface of the flange portion 50 of the lower casing 2 as shown in FIG. 2A, and the upper case 3 is fitted from above the lower casing 2.

Then, the upper casing 3 is pushed down until the facing portion of the upper casing 3 comes into contact with the upper surface of the flange portion 50 of the lower casing 2, and the portion 32 located below the hole 31 is moved toward the center of the upper casing 3 (that is, Pushing toward the rod 10) to cause plastic deformation,
The flange 50 is engaged with the tapered lower surface.

By deforming the portion 32 and engaging the tapered lower surface of the flange portion 50 in this manner, the upper casing 3 is fixed to the flange portion 50 of the lower casing 2.
The upper casing 3 does not necessarily have to be pushed down so as to come into contact with the lower lower casing 2 before the portion 32 is plastically deformed.

FIG. 2A shows a state in which the casing 32 is fastened by plastically deforming the portion 32 in a convex shape. The O-ring 51 is reliably compressed. In the above embodiment, when the cam 25 rotates in conjunction with the engine,
The cam 25 drives the roller 23, which is a pump drive unit,
The pump rod 10 and the piston rod 6 are moved up and down.

When the piston 6 rises, the pump upper chamber 14
The air inside is discharged into the space inside the head cover 4 through the discharge valve 19, and the air is sucked into the pump lower chamber 15 from a brake booster (not shown) through a pipe 16 and an intake valve (not shown). At the same time, the lubricating oil directly supplied to the bearing opening 24 through the communication hole 28 from the oil nozzle 29a serving as an oil supply means is generated by the negative pressure in the pump lower chamber 15, and the gap between the bearing 11 and the piston rod 10 is generated.
And is sucked into the lower pump chamber 15 through the oil passage 12a and diffused into the lower pump chamber 15.

As the piston reciprocates up and down, lubricating oil flows into the pump lower chamber 15 and adheres to the sliding surface between the piston ring 9 and the cylinder 5 to maintain the lubrication state.

When the piston 6 descends, the pump lower chamber 15
The air inside is discharged to the space inside the head cover 4 through the discharge valve 20, and the air is sucked into the pump upper chamber 14 from the brake booster through the pipe 16 and the suction valve 17. or,
The lubricating oil attached to the vicinity of the cylinder 5 and the piston ring 9 on the pump lower chamber 15 side flows into the pump upper chamber 14 side from the pump lower chamber 15 due to the negative pressure of the pump upper chamber 14, and diffuses into the pump upper chamber 14. .

By repeating the reciprocating motion of the piston 6, lubricating oil further flows into the pump upper chamber 14 and adheres to the sliding surfaces of the piston ring 9 and the cylinder 5.
The sliding surface of the piston is lubricated.

Oil passage 12 communicating with the lower pump chamber 15
The inflowing lubricating oil adheres to a, and the oil passage 1
It is possible to prevent unnecessary air from being sucked into the pump lower chamber 15 from 2a.

Since the upper casing 3 is formed in a cup shape having a hanging portion, it has a high rigidity even if it is a thin plate, and it is in close contact with the upper surface of the flange portion 50 of the lower casing 2 over the entire circumference. The amount of compression is secured, and no gap is created between the upper casing 3 and the upper surface of the flange portion 50 of the lower casing 2.

Therefore, the sealing action of the sealing O-ring 51 is reliable, and the space in the pump upper chamber 14 does not become large due to the gap. Further, the foreign matter in the lubricating oil discharged from the oil nozzle 29a flows downward through the communication hole 28 formed in the flange 26 at the lower portion of the piston rod 10 and does not accumulate, so that the bearing 11 and the piston rod 1
It is not sucked into the sliding part with 0.

7 and 8 show a second embodiment corresponding to claim 2, in which the lower surface of the flange portion 50A of the lower casing 2 is formed in a horizontal plane, unlike the tapered shape of the first embodiment, and the flange is formed. It is parallel to the upper surface of the portion 50A.

The shape of the hole 31A provided on the outer periphery of the upper casing 3A is different from that of the first embodiment. In the second embodiment, the lower surface of the hole 31A is provided with inclined surfaces 34A and 34A that are lowered downward toward the center of the hole in the circumferential direction, and when both casings are fastened, the inclined surfaces 34A and 34A are The upper casing 3A is brought into contact with the upper surface of the flange portion 50A by engaging with the ridge line portion of the outer peripheral lower end of the flange portion 50A of the lower casing 2.

Although the assembly drawing of the embodiment corresponding to claim 3 is not shown, a lower casing having the flange portion 50 of the first embodiment is used, and an upper casing is inclined as in the second embodiment. Using 3A with surface 34A,
It is configured by combining these lower casing and upper casing.

When the two are fastened together, the portion 33A of the upper casing 3A is moved to the upper casing 3A.
To push it toward the center of and plastically deform it into a convex shape,
This is similar to the case of the second embodiment.

[0047]

Since the piston type fluid pump of the present invention is constructed as described above, not only can the weight be reduced, but also the compression amount of the O-ring can be secured and the sealing performance can be secured.

Even if the lower casing flange portion is a non-circular irregular shape, a gap between the upper casing and the lower casing flange portion, which has a great influence on the ultimate vacuum, does not occur, so that the pump upper chamber corresponding to the gap is formed. No increase in volume occurs. Therefore, a vacuum pump with good performance can be realized by reducing the weight.

Furthermore, since screws are not used for fastening the upper casing, the number of man-hours for processing parts and the number of assembling steps can be reduced, and the caulking jig / device can be simplified.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a first embodiment of the present invention.

2A is an enlarged view of a main part of FIG. 1, and FIG. 2B is an enlarged view of a main part before the upper casing is caulked.

FIG. 3 is a side view of an upper casing used in the first embodiment of FIG.

FIG. 4 is a plan view of the first embodiment of FIG.

5 is a side view of the lower portion of the first embodiment of FIG. 1 broken away.

6 is a bottom view of the first embodiment of FIG. 1. FIG.

FIG. 7 is an enlarged vertical sectional view of an essential part of the second embodiment of the present invention.

FIG. 8 is a side view of an upper casing used in the second embodiment shown in FIG.

[Explanation of symbols]

2 Lower casing 3, 3A Upper casing 5 Cylinder 6 Piston 31, 31A Hole 32, 32A Part of hanging part located below hole 31, 31A 34A Inclined surface 50, 50A Flange 51 O ring

Front Page Continuation (72) Inventor Issei Hanai 1-1-1, Kyowa-cho, Obu-shi, Aichi Aisan Industry Co., Ltd.

Claims (3)

[Claims] 1. A vacuum pump having a piston that moves up and down between an upper casing and a lower casing, and a sealing O-ring sandwiched between the casings, which is press-formed into a cup having a hanging portion on the outer circumference. And an upper casing (3) having a plurality of holes (31) provided in the hanging portion of the outer periphery at intervals in the circumferential direction, and a lower surface of the flange portion (50) close to the center of the lower casing (2). A lower casing (2) formed in a taper shape that is more distant from the upper surface of the flange portion (50), and the upper casing (3) is fitted into the flange portion (50) of the lower casing (2), A portion (32) of the hanging portion of (3) located below the hole (31) is plastically deformed toward the center of the upper casing (3) to form both casings. A piston type fluid pump, characterized in that the (3) and (2) are fastened. 2. A vacuum pump having a piston that moves up and down between an upper casing and a lower casing, and a sealing O-ring sandwiched between the casings, which is press-formed into a cup having a hanging portion on the outer periphery. And a plurality of holes (31A) provided at intervals in the circumferential direction at the hanging portion of the outer circumference, and an inclined surface (34A) inclined with respect to the circumferential direction of the outer circumference is provided at the lower surface of the holes. The upper casing (3A) is provided, the upper casing (3A) is fitted to the flange portion (50A) of the lower casing (2), and the lower portion of the hanging portion of the upper casing (3A) is located below the hole (31A). A piston characterized in that the casing (3A) (2) is fastened by plastically deforming the portion (32A) to be formed in the center direction of the upper casing (3A). Fluid pump. 3. A vacuum pump having a piston that moves up and down between an upper casing and a lower casing, and a sealing O-ring sandwiched between the casings, and the upper casing (3A) according to claim 2. The lower casing (2) according to claim 1, wherein the upper casing (3A) is fitted to the flange portion (50A) of the lower casing (2), and the hole is provided in the hanging portion of the upper casing (3A). A piston type fluid pump, characterized in that a portion (32A) located below (31A) is plastically deformed toward the center of the upper casing (3A) to fasten both casings (3A) and (2).