JPH08319951A - Piston type vacuum pump - Google Patents

Abstract

PURPOSE: To provide a prolonged life for a pump by improving lubrication of the slide part of the interior of a pump. CONSTITUTION: Lubrication oil 30 delivered from the oil nozzle 29a of an oil feed means 29 is collided with a recess 2d formed in the conical surface of a lower casing 2 and concentrated to the lower end part 11a of a bearing 11. The lubrication oil 30 is sucked in a gap between a bearing 11 and a piston rod 10 by a pump negative pressure generated through vertical reciprocating movement of a piston 6. Further, the lubrication oil flows through the oil passage 12a of a seal ring 12 and is diffused in a pump chamber 15 and a pump upper chamber 14.

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.

[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. 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 pump is driven by a vehicle engine, and the working piston moves up and down.

A compression coil 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 is a Teflon seal ring provided on the lower casing 2 so as to be fitted to the rod 10.
In particular, as shown in an enlarged view in FIGS. 6 and 7, oil passages 12a are formed at four locations on the inner circumference thereof.

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 periphery of the small-diameter roller 22. The radial 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, which urge the piston rod 10 downward. The large-diameter roller 23 is pressed against the disk cam 25.

The compression coil springs 27A, 27
In B and 27C, the load is reduced as the mass of the piston 6 is reduced. The large-diameter roller 23 thus configured functions as a pump drive unit that follows the disc cam 25. Reference numeral 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 has a bearing opening 24 and oil nozzles 29a and 29b for supplying lubricating oil to the outer peripheral surface of the large-diameter roller 23 which is a pump drive portion.

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 pump 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 cylinder head cover 4 via the discharge valve 20, and the air is sucked into the pump upper chamber 14 from the brake booster via the pipe 16 and the suction valve 17. Further, 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 enters the pump upper chamber 14 inside. Spread.

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 1
It is possible to prevent unnecessary air from being sucked into the pump lower chamber 15 from 2a.

Further, the foreign matter attached to the root portion of the piston rod 10 in the flange 26 is naturally dropped from the communication hole 28 to the outside together with the lubricating oil and discharged. JP-A-5
The vacuum pump described in Japanese Patent Laid-Open No. 106556 is proposed by the applicant of the present application, and the applicant has since produced the vacuum pump 1 having the shape shown in FIGS. 8 and 9.

The structure of the vacuum pump shown in FIGS. 8 and 9 is basically the same as that of the vacuum pump described in FIGS. 5, 6 and 7, but the pipe 16, the suction valve 17, 1
8 and the discharge valves 19 and 20 are not shown and are not shown.

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

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. 9, and reference numeral 2b. The lower end shown by has a convex cross section of R.

In FIGS. 8 and 9, 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 indicated by reference numeral 30a in FIG. Is scattered in the outer peripheral direction of the tapered portion 2a,
As shown by 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 face the clearance between the lower end of the bearing 11 and the rod 10.

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

[0029]

SUMMARY OF THE INVENTION In the above conventional technique,
The lubricating oil 30 discharged from the oil nozzle 29a is intended to be aimed near the lower end of the bearing 11, but in reality, the lubricating oil 30 hits the convex portion 2b of the cross section R of the lower casing 2 and most of it 30a Since it scatters in a direction that is not useful for lubrication of the sliding part, the lubrication inside the vacuum pump such as the sliding part between the bearing 11 and the rod 10 is not sufficient, and wear due to oil shortage occurs and pump life is extended. There was a problem that it had an adverse effect.

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

[0031]

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 (30) discharged from an oil nozzle (29a) provided in an engine as a piston ( 6) Due to the negative pressure generated by the reciprocating motion of the piston rod (10) and its bearing (1
In the piston type vacuum pump (1) that sucks through the gap between the piston (1) and the inside of the pump to lubricate the inside of the pump, it is a part of the casing (2) that holds the bearing (11) and is discharged from the oil nozzle (29a). The feature is that the portion (2d) against which the lubricating oil (30) hits is formed in a concave shape.

According to the present invention, the lubricating oil (30) discharged from the oil nozzle (29a) flows so as to enter the recessed portion (2d) of the casing (2), and the bearing (11 ) Is guided to the end (11a).

According to a second aspect of the invention, in the piston type vacuum pump according to the first aspect, the concave portion (2d) is a conical surface which is concave upward.

In the present invention, the lubricating oil (30) discharged from the oil nozzle (29a) flows along the inner surface of the conical surface (2d) of the casing (2), and the end portion (11a) of the bearing (11). Be led to.

According to the invention of claim 3, the lubricating oil (30) discharged from the oil nozzle (29a) provided in the engine.
In the piston-type vacuum pump (1) that sucks the oil from the gap between the piston rod (10) and its bearing (11) by the negative pressure generated by the reciprocating motion of the piston (6) to lubricate the inside of the pump, the bearing (11 ) Is a part of the casing (2), and the portion (2e) against which the lubricating oil (30) discharged from the oil nozzle (29a) hits is formed into a flat surface.

In the present invention, the lubricating oil (30) discharged from the oil nozzle (29a) hits the plane (2e) of the casing (2) to change its direction, and flows along the plane (2e) to cause the bearing. It is guided to the end (11a) of (11).

[0037]

1 and 2 show a first embodiment of the present invention, in which the pipe, suction valve and discharge valve are not shown in the same manner as in FIG. 8 of the prior art.

In FIGS. 1 and 2, 1 is a piston type vacuum pump, 2 is a lower casing, 3 is an upper casing, and this vacuum pump 1 is below the lower casing 2 and has a cylinder head cover 4 of an engine.
It is fixed to.

Reference numeral 5 is a cylindrical cylinder fixed to the lower casing 2, 6 is a piston that reciprocates up and down in the cylinder 5, and an O-ring 8 and a Teflon piston ring 9 are provided in an annular groove 7 provided on the outer periphery thereof. Are fitted. 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 cylindrical bearing 11 provided in the lower casing 2, and the upper end thereof is fixed to the center of the piston 6. 11a is the lower end of the bearing 11.

Reference numeral 12 is a Teflon seal ring provided in the lower casing 2 so as to be fitted into the piston rod 10. As described with reference to FIGS.
Oil passages 12a are formed at four locations on the inner circumference 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, respectively.
Respectively communicate with the brake booster and the space inside the cylinder head cover 4 via an intake valve and a discharge valve (not shown). The pump lower chamber 15 communicates with the space inside the brake booster and the cylinder head cover 4 via another intake valve and a discharge valve, which are not shown.

Reference numeral 21 is a pin fixed to the lower end of the piston rod 10, 22 is a small-diameter roller fitted to the pin 21 so as to be able to rotate, and 23 is a large-diameter roller fitted to the outer periphery of the small-diameter roller 22. The radial roller 23 is in contact with the outer peripheral cam surface of a disc cam 25 formed on the cam shaft of the engine.
Reference numeral 25a indicates the axis of the camshaft.

Reference numeral 24 is a bearing opening located below the bearing 11, 26 is a flange formed near the lower end of the piston rod 10, and 27 is a compression coil spring arranged between the flange 26 and the lower casing 2. , Two compression coil springs 27A and 27B arranged concentrically, and urges the piston rod 10 downward to press the large diameter roller 23 against the outer peripheral cam surface of the disc cam 25.

The large-diameter roller 23 thus constructed is
It functions as a pump drive unit that follows the disc cam 25.
Reference numeral 28 is a communication hole provided in the flange 26. Reference numeral 29 denotes an oil supply means provided in the cylinder head 31, which has bearing openings 24 and oil nozzles 29a and 29b for supplying lubricating oil to the outer peripheral surface of the large-diameter roller 23 which is a pump drive section.

Reference numeral 32 denotes a columnar 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 relative postures of the large diameter roller 23 and the disc cam 25 are maintained. That is, the parallel relationship between the axes of the large diameter roller 23 and the disc cam 25 is maintained, and the disc cam 25
The engagement relationship between the outer peripheral cam surface and the outer peripheral surface of the large diameter roller 23 is favorably maintained.

Reference numeral 30 denotes the lubricating oil discharged from the oil nozzle 29a and flying in the space toward the bearing opening 24. Reference numeral 2c denotes a cylindrical portion that constitutes a bearing holding portion of the lower casing 2, and the lower end of the cylindrical portion 2c is formed as a conical surface portion 2d that is recessed upward.

Therefore, the lubricating oil 30 discharged from the oil nozzle 29a to the space obliquely above is propelled toward the bearing opening 24, and has a concave shape formed by the lower conical surface of the cylindrical portion 2c of the lower casing 2. The concave portion 2d is formed along the inner surface of the conical surface by hitting the concave portion 2d.
The flow is guided so as to enter the inner part of the bearing 11 and concentrates on the lower end 11 a of the bearing 11.

Then, the negative pressure of the pump lower chamber 15 due to the reciprocating vertical movement of the piston 6 is sucked into the gap between the bearing 11 and the piston rod 10, and further passes through the oil passage 12a to pass through the pump lower chamber 15 and the pump upper chamber. It diffuses in 14 and adheres to the sliding portion between the piston ring 9 and the cylinder 5.

In this way, the lubricating oil 30 is used inside the pump 1 such as the sliding portion between the bearing 11 and the piston rod 10, the sliding portion between the seal ring 12 and the piston rod 10, and the sliding portion between the piston ring 9 and the cylinder 5. Lubricate.

In the first embodiment, the lower end portion 11a of the bearing 11 is aligned with the innermost portion of the upper end of the concave portion 2d formed by the conical surface formed at the lower end of the cylindrical portion 2c of the lower casing 2. is there. By doing this, the conical surface 2
The lubricating oil 30 concentrates on the lower end portion 11a of the bearing 11 along d, and is effectively sucked into the gap between the bearing 11 and the piston rod 10.

Next, a second embodiment of the present invention shown in FIGS. 3 and 4 will be described. In the second embodiment, the lower end portion 2e of the cylindrical portion 2c of the lower casing 2 has the piston rod 1
The first embodiment described with reference to FIGS. 1 and 2 is that the length (position) of the lower end portion 11a of the bearing 11 is set in a plane perpendicular to the axis center of 0 and aligned with the position of this plane. Different from the example.

In the second embodiment, the lubricating oil 30 discharged from the oil nozzle 29a into the space flies toward the bearing opening 24 and hits the flat surface 2e to change its direction.
It flows to the lower end 11a of the bearing 11 along e, is sucked by the negative pressure of the pump into the gap between the bearing 11 and the piston rod 10, and lubricates the inside of the pump.

[0055]

Since the piston-type vacuum pump of the present invention is constructed as described above, the lubricating oil discharged from the oil nozzle and propelled toward the bearing opening is in the cylindrical portion of the lower casing. Since it is guided to the lower end of the bearing by hitting the concave part formed at the lower end or the flat surface, the ratio of the lubricating oil utilized for lubricating the inside of the pump due to the negative pressure of the pump increases and the sliding part of the pump slides. Lubrication is improved and pump life can be extended.

[Brief description of drawings]

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

FIG. 2 is an enlarged view of a part of FIG.

FIG. 3 is a vertical sectional view of a second embodiment of the present invention.

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

FIG. 5 is a vertical cross-sectional view of a conventional technique.

FIG. 6 is an enlarged view of a part of FIG.

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

FIG. 8 is a vertical cross-sectional view of a conventional technique.

9 is an enlarged view of a part of FIG. 8. FIG.

[Explanation of symbols]

 1 Piston type vacuum pump 2 Lower casing 2a Cylindrical part 2d Recessed conical surface 2e Plane 6 Piston 10 Piston rod 11 Bearing 11a Lower end of bearing 11 29a Oil nozzle 30 Lubricating oil

Claims (3)

[Claims] 1. A piston-type vacuum that lubricates the inside of a pump by sucking lubricating oil discharged from an oil nozzle provided in an engine from a gap between a piston rod and its bearing by negative pressure generated by reciprocating motion of a piston. In the pump, a piston-type vacuum pump characterized in that a part of a casing that holds a bearing and a part of the casing that is in contact with the lubricating oil discharged from an oil nozzle is formed in a concave shape. 2. The piston type vacuum pump according to claim 1, wherein the concavely formed portion is a conical surface which is recessed upward. 3. A piston-type vacuum that lubricates the inside of the pump by sucking the lubricating oil discharged from an oil nozzle provided in the engine from the gap between the piston rod and its bearing by the negative pressure generated by the reciprocating motion of the piston. In the pump, a piston-type vacuum pump is characterized in that a part of a casing that holds a bearing and a part of the casing that is in contact with the lubricating oil discharged from an oil nozzle is formed into a flat surface.