JPH08319947A - Piston type vacuum pump - Google Patents

Abstract

PURPOSE: To provide an increased life for a pump through prevention of running out of oil of the bearing of a piston rod. CONSTITUTION: A tubular member 32A coupled to an oil feed means 29 attached to a cylinder head 31 is fitted in a lower casing 2. An oil passage 33 is formed in the lower casing 2 in such a state to be communicated with the hole of the member 32a and the downstream part of the oil passage 33 is communicated with a hole formed in the intermediate part 11a of a bearing 11. A groove 10a, serving as an oil reservoir, formed in the outer periphery of a piston rod 10 is positioned facing a hole, formed in the intermediate part 11a of the bearing 11, at the top dead center of the piston rod 10 and lubrication oil is forcibly fed through the oil passage 33 to the groove.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art As a pump of this kind, 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. A roller provided at one end of the rod of the piston is driven by a disc cam that interlocks with the engine so that the working piston moves up and down so that this pump is driven by the vehicle engine.

A compression spring for urging the piston rod downward is provided so that the piston rod can follow the rotation of the disc cam, and the roller is pressed against the disc cam.

The vacuum pump described in the above-mentioned JP-A-5-106556 is shown in FIGS. A vacuum pump 1 includes a lower casing 2 and an upper casing 3, and is fixed to a cylinder head cover 4 of the engine at a lower portion of the lower casing 2.

Reference numeral 5 is a cylindrical 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. Have been combined. 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.

The central portion of the lower surface of the piston 6 is dented upward, and the mass of the piston 6 is reduced by setting the thickness of the central portion of the piston 6 to the minimum necessary strength. 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 6.

Reference numeral 12 denotes a Teflon seal ring provided in the lower casing 2 so as to be fitted to the piston rod 10. Particularly, as shown in an enlarged view in FIGS. 4 and 5, an oil passage 12a is formed at four inner circumferences thereof. Has been done.

Reference numeral 13 is 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).

A portion of the lower casing 2 forming the central portion of the bottom surface of the pump lower chamber 15 is formed in an upwardly bulging shape, and a sealing member such as the seal ring 12 or the O-ring 13 is provided at the center of the bulging portion. A shaft seal holding portion for holding is formed.

Intake valves 17 and 18 are provided between the pipe 16 and the pump upper chamber 14, and between the pipe 16 and the pump lower chamber 15, respectively.
It is arranged between and. The pump upper chamber 14 and the pump lower chamber 15 communicate with the space inside the cylinder 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 circumference of the small diameter roller 22. The large-diameter roller 23 is in contact with a disc cam 25 formed on the cam shaft of the engine. Reference numeral 25a indicates the axis of the camshaft.

Reference numeral 26 is a flange formed near the lower end of the piston rod 10, and 27A, 27B and 27C are compression coil springs arranged between the flange 26 and the lower casing 2, for urging the piston rod 10 downward. The large diameter roller 23 is pressed against the cam 25.

The large-diameter roller 23 thus constructed is
It functions as a pump drive unit that follows the cam 25. 24
Is a bearing opening located below the bearing 11, and 28 is a communication hole provided in the flange 26. Reference numeral 29 denotes an oil supply means, which is a bearing opening 24 and a large-diameter roller 2 which is a pump drive portion.
Oil nozzles 29a and 2 for supplying lubricating oil to the outer peripheral surface of 3
9b.

An oil nozzle 29 as an oil supply means
The lubricating oil ejected from a passes through the communication hole 28 of the flange 26, directly reaches the bearing opening 24, further passes through the gap between the bearing 11 and the piston rod 10, and is sucked into the pump lower chamber 15 through the oil passage 12a. It

In the above vacuum pump, when the disc cam 25 rotates counterclockwise as shown by the arrow in conjunction with the engine, the disc cam 25 causes the large-diameter roller 23, which is a pump drive portion.
Is driven to vertically move the piston rod 10 and the piston 6.

When the piston 6 rises, the pump upper chamber 14
The air inside is discharged into the space inside the cylinder 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 the pipe 16 and the suction valve 18. 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 the 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, and The oil is sucked into the pump lower chamber 15 through the oil passage 12a and diffuses into the pump lower chamber 15.

By repeating the reciprocating movement of the piston 6 up and down, the 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 movement of the piston 6, the 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 to maintain the lubricating state. In this way, 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 12a
It is possible to prevent unnecessary air from being sucked into the pump lower chamber 15. Further, the foreign matter attached to the root portion of the piston rod 10 in the flange 26 is naturally dropped to the outside from the communication hole 28 together with the lubricating oil and discharged.

The vacuum pump described in the above-mentioned Japanese Patent Laid-Open No. 5-106556 was proposed by the applicant of the present application, and the applicant has since produced the vacuum pump 1 having the shape shown in FIGS. 6 and 7.

The structure of the vacuum pump shown in FIGS. 6 and 7 is basically the same as that of the vacuum pump described in FIGS. 3, 4 and 5, but the pipe 16, the suction valves 17, 18 and the discharge valve 19, 20 is not shown and is not shown.

Further, since the direction of seeing the cross section is seen from the opposite direction to the axis 25a of the cam shaft, the rotation direction of the disc cam 25 is apparently the opposite clockwise direction. Similarly, the oil supply means 29 is the roller 22 in FIG.
It is drawn in the form arranged at the lower left of 23.

The substantially cylindrical portion of the lower casing 2 which holds the bearing 11 has a slight taper whose diameter becomes smaller as it goes downward as indicated by reference numeral 2a in FIG. 7, and reference numeral 2b. The lower end shown by has a convex cross section of R.

In FIGS. 6 and 7, 30 is an oil nozzle 29a.
The lubricating oil is discharged from the air and flies in the space toward the bearing opening 24. The lubricating oil 30 hits the lower end portion 2b of the lower casing 2 and most of the lubricating oil is tapered as indicated by reference numeral 30a in FIG. Scatter in the outer peripheral direction of the portion 2a,
As shown by the reference numeral 30b, only a part thereof flows horizontally along the lower end surface of the cylindrical portion of the lower casing 2 so as to go toward the clearance between the lower end of the bearing 11 and the piston rod 10.

A part of the lubricating oil 30b is sucked into the gap between the bearing 11 and the rod 10 by the negative pressure in the lower chamber 15 of the vacuum pump 1 to lubricate the sliding portion. 31 is a cylinder head.

Reference numeral 32 denotes a cylindrical rod having an upper end press-fitted and fixed to the lower casing 2, and a lower end thereof extends downward from the lower casing 2 and extends below the flange 26. The flange 26 extends downwardly through a notch 26a provided at one location on the outer periphery of the flange 26. By doing so, the rod 32 and the notch 26a are engaged, and the rod 32 acts as a detent pin that restricts the rotation of the flange 26, that is, the piston rod 10.

Therefore, the large diameter roller 23 and the disk cam 25 are
The relative posture of is maintained. That is, the parallel relationship between the axes of the large-diameter roller 23 and the disc cam 25 is maintained, and the engagement relationship between the outer peripheral cam surface of the disc cam 25 and the outer peripheral surface of the large-diameter roller 23 is favorably maintained.

[0031]

SUMMARY OF THE INVENTION In the above conventional technique,
The lubricating oil 30 discharged from the oil nozzle 29a hits the convex portion 2b of the cross section R of the lower casing 2, and most of the portion 30a scatters in a direction not useful for lubricating the sliding portion such as the bearing 11. Not only the bearing 1
The lubricating oil that has entered the gap between the piston rod 10 and the piston rod 10 is sucked upward by the negative pressure of the pump chamber and moves to the pump lower chamber 15, so that the oil film in the sliding portion between the bearing 11 and the piston rod 10 runs out. However, there is a problem in that the sliding portion is greatly worn and the durability of the vacuum pump is impaired.

Therefore, an object of the present invention is to provide a piston type vacuum pump which can prevent the oil film from running out in the gap between the bearing 11 and the piston rod 10 and solve such a problem.

[0033]

In order to achieve the above-mentioned object, a piston type vacuum pump according to a first aspect of the present invention uses a lubricating oil supplied to a gap between a bearing (11) and a piston rod (10) as a piston ( In the piston type vacuum pump which sucks into the pump chamber (15, 14) by the negative pressure generated by the reciprocating motion of 6) to lubricate the sliding portion of the piston (6) and the cylinder (5), the oil supply means (2
It is characterized in that an oil passage (33) for directly supplying lubricating oil is provided from 9) to the intermediate portion (11a) in the longitudinal direction of the bearing (11).

In the present invention, the lubricating oil is supplied from the oil supply means (29) through the oil passage (33) to the longitudinal intermediate portion (11a) of the bearing (11), and the bearing (11a) is fed from the longitudinal intermediate portion (11a). Lubricating oil is diverted toward both ends of (11), and the bearing (11) and the piston rod (1
An oil film is formed in all the gaps with 0).

According to a second aspect of the present invention, in the piston type vacuum pump according to the first aspect, the piston rod (1) facing the intermediate portion (11a) in the longitudinal direction of the bearing (11).
It is characterized in that a groove (10a) surrounding the outer circumference of the piston rod (10) is formed on the outer circumference of (0) to form an oil reservoir.

In the present invention, in addition to the action of the piston type vacuum pump described in claim 1, the groove (10a) acts as an oil reservoir. According to a third aspect of the present invention, in the piston type vacuum pump according to the second aspect, at the position of the top dead center or the bottom dead center of the piston rod (10), the bearing portion (11) is provided with the longitudinal intermediate portion (11a). Groove (1
0a) are opposed to each other.

In the present invention, since the groove (10a) is supplied with oil at the position of the top dead center or the bottom dead center of the piston rod (10), the fluid resistance of the oil passage (33) is less likely to be adversely affected. A sufficient amount of oil can be stored in the groove (10a).

According to a fourth aspect of the present invention, in the piston type vacuum pump according to the first aspect, the oil sump (34) is formed on the lower body (2) side of the longitudinal intermediate portion (11a) of the bearing (11). It is characterized by that.

In the present invention, the amount of oil supplied to the oil sump (34) does not change due to the vertical movement of the piston rod.
According to a fifth aspect of the present invention, in the piston type vacuum pump according to any one of the first to fourth aspects, a member (32A) forming an oil passage is engaged with a flange (26) of the piston rod (10). The feature is that it also serves as a detent for the piston rod.

In the present invention, the member (32A) forming the oil passage also serves as a rotation stopper for the piston rod (10), so that the structure can be made compact.

[0041]

1 is a first embodiment of the present invention. Parts (elements) having the same functions as those of the prior art shown in FIG. 6 are given the same reference numerals as those in FIG. 6 and their explanations are omitted.

The first embodiment differs from the prior art described in FIGS. 6 and 7 in the lubricating oil supply system for the sliding portion between the bearing 11 and the piston rod 10. In the first embodiment of FIG. 1, 29 is an oil supply means attached to the cylinder head 31, and supplies the lubricating oil discharged from the oil nozzle 29b to the outer peripheral surface of the large-diameter roller 23 which is the pump drive part.

The remaining lubricating oil of the oil supply means 29 passes through a member 32A forming a part of a pipe-shaped oil passage and an oil passage 33 provided in the lower casing 2,
Oil is forcibly fed into the annular groove 10a of the piston rod 10 through a hole formed in the intermediate portion 11a of the bearing 11 in the longitudinal direction (vertical direction in the drawing).

The state shown in the figure shows when the piston 6 is at the top dead center, and thus the piston 6 and the piston rod 10 are
Is located at the top dead center position, the groove 10a is provided so that the annular groove 10a just faces the hole opened in the longitudinal intermediate portion 11a of the bearing 11.

Thus, the groove 10a functions as a kind of oil reservoir. In this way, the annular groove 1 at the top dead center position is
When the relative position is determined so that 0a faces the hole opened in the longitudinal intermediate portion 11a of the bearing 11, the oil passage 33 supplies oil to the annular groove 10a as an oil reservoir at the top dead center position where the moving speed is the slowest. Therefore, the oil passage 33
Even if the passage cross-sectional area of
Sufficient lubricating oil can be filled.

The lubricating oil filled in the groove 10a is
Flows in both the upper and lower directions of the bearing to form an oil film in the gap between the bearing 11 and the piston rod 10. In the first embodiment of FIG. 1, the groove 1 is formed at the bottom dead center position of the piston rod 10.
0a is made to face the hole of the intermediate portion 11a, but even if both of them face each other at the top dead center position of the piston rod 10, oil is supplied to the groove 10a as an oil reservoir when the speed of the piston rod is zero. The advantages of being done are the same.
However, in this case, it is necessary to shift the position of 10a downward in the drawing, which is disadvantageous to the first embodiment in terms of forming the downstream portion of the oil passage 33.

FIG. 2 shows a second embodiment of the present invention, which is different in that an annular groove as an oil reservoir is formed in the lower casing 2 around the piston rod 10. An annular groove is shown at 34, in order to do this, the bearing 11 is
1A and the lower portion 11B were divided into two, and an annular groove 34 was formed between them to communicate with the oil passage 33.

In the second embodiment, the piston rod 10
This is different from the first embodiment in that the relationship between the groove as an oil reservoir and the oil passage does not change due to the vertical movement of the. In both of the embodiments, the member 32A engages with the notch 26a on the outer periphery of the flange 26 to prevent the piston rod 10 from rotating.
By arranging at the position of the rotation stop 32 in the above, even if a member 32A for the oil passage is newly provided, the whole is made compact.

[0049]

Since the piston type vacuum pump of the present invention is constructed as described above, the lubricating oil can be forcibly pumped and supplied to the sliding portion between the bearing and the piston rod, so that the amount of oil in the bearing portion increases. And the lubrication is improved,
The oil will not run out easily. Therefore, there are effects such that the reliability of the vacuum pump is improved and the durability is extended.

[Brief description of drawings]

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

FIG. 2 is a vertical sectional view of a second embodiment of the present invention.

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

FIG. 4 is an enlarged view of a part of FIG.

5 is a cross-sectional view of the seal ring of FIG.

FIG. 6 is a vertical cross-sectional view of another prior art.

FIG. 7 is an enlarged view of a portion of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Piston type vacuum pump 2 ... Lower casing 5 ... Cylinder 6 ... Piston 10 ... Piston rod 10a ... Groove 11 ... Bearing 11a ... Intermediate part 14 ... Pump upper chamber (pump chamber) 15 ... Pump lower chamber (pump chamber) 26 ... Flange 29 ... Oil supply means 32A ... Member 33 ... Oil passage 34 ... Oil sump

Claims (5)

[Claims] 1. A piston-type vacuum that lubricates a sliding portion between a piston and a cylinder by sucking lubricating oil supplied to a gap between a bearing and a piston rod into a pump chamber by negative pressure generated by reciprocating motion of the piston. A piston-type vacuum pump, characterized in that an oil passage for directly supplying lubricating oil from an oil supply means is provided to an intermediate portion in the longitudinal direction of the bearing. 2. The piston type vacuum pump according to claim 1, wherein a groove surrounding the outer circumference of the piston rod is formed in the outer circumference of the piston rod facing the intermediate portion in the longitudinal direction of the bearing to form an oil reservoir. . 3. The piston type vacuum pump according to claim 2, wherein the groove faces the intermediate portion in the longitudinal direction of the bearing at the position of the top dead center or the bottom dead center of the piston rod. 4. An oil reservoir is formed on the lower body side of the intermediate portion in the longitudinal direction of the bearing.
Piston type vacuum pump described. 5. The piston type according to claim 1, wherein the member forming the oil passage engages with the flange of the piston rod and also serves as a rotation stopper for the piston rod. Vacuum pump.