JPH09280297A - Hydraulic buffer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the number of parts and the assembly man-hour required for the assembly of a pump rod. SOLUTION: In a hydraulic cylinder having the self-pumping mechanism in which a case 21 is demarcated into upper and lower chamber by a partitioning member 22, a cylinder 26 containing a piston and a hollow piston rod is arranged in the upper case chamber, and a pump rod 31 to pump the oil in the lower case chamber 28 into a pump chamber in the piston rod is connected to the partitioning member 22, a base end part of the pump rod 31 is fitted in a recessed part 84 provided in the partitioning member 22, and a disk 91 in which an inner circumferential edge part is fitted in a circumferential edge part is fitted in a circumferential groove 90 provided in the pump rod 31 is loaded on a disk loading surface 22b of the partitioning member 22. The axial force of the cylinder 26 is applied thereto through a retainer 92 and a base valve 30, the inner circumferential edge part of the disk 91 is elastically deflected making use of the step δ between the disk loading surface 22b and the circumferential groove 90 of the pump rod 31, and the pump rod 31 is held to the partitioning member 22 by the deflection.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic shock absorber mounted on a suspension device of an automobile or the like, and more particularly to a hydraulic shock absorber having a self-pumping mechanism for controlling the extension length of a piston rod within a certain range. It is related to vessels.

[0002]

2. Description of the Related Art In this type of hydraulic shock absorber, a case having a bottomed cylindrical shape is divided into two chambers by a partition member, and an oil liquid is sealed in a bottom side chamber (oil tank) of the case.
A cylinder filled with oil is placed in the chamber on the opening side,
The inside of the cylinder and the reservoir chamber around the cylinder,
A piston having a damping force generating mechanism is slidably mounted in the cylinder so as to be communicated with each other through a base valve arranged between the cylinder and the partition member, and the piston is provided in the opening of the case and the cylinder. The base end of a hollow piston rod whose tip extends through the mounted sealing means to the outside of the cylinder is connected, and further, the piston rod is operated in accordance with the expansion and contraction movement of the piston rod, and the partition There is a self-pumping mechanism that lifts the oil liquid in the bottom chamber of the case into the cylinder through a pump rod extending from a member into the piston rod.

FIG. 10 shows the structure around the base valve of such a hydraulic shock absorber. In the figure, 1 is a case, 2 is a partition member, 3 is a cylinder, 4 is a base valve, 5 is a pump rod which constitutes a self-pumping mechanism, and an inner chamber (lower chamber) 6 of the cylinder 3 and its surroundings. The reservoir chamber 7 of the base valve 4
Is communicated with the oil passage 8 provided in the main body 4 a of the pump rod 5, and the internal passage 9 of the pump rod 5 and the bottom side chamber 10 of the case 1 are
The partition member 2 and the main body 4 a of the base valve 4 are communicated with each other by a through hole 12 of a retainer 11 interposed therebetween. The base valve 4 has a reservoir chamber 7 through an oil passage 8.
Check valve 1 that allows the flow of oil from the lower chamber 6 to the cylinder
3 has an orifice 14 that constantly connects the oil passage 8 with the oil passage 3.

The pump rod 5 is slidably fitted at its tip into a spherical recess 11a formed in the retainer 11 so that the pump rod 5 can be tilted in the radial direction during operation. The position is fixed to the retainer 11 by 16. This connecting means 16 is an engagement ring 17 that fits in an annular groove provided on the peripheral surface of the pump rod 5.
And a holding ring 18 for holding the outer surface of the engagement ring 17.
And a stopper plate 19a that is caulked to a nut 19 that is screwed into the retainer 11. According to such a connecting means 16, the stopper plate 17a presses the back surface of the presser ring 18 by tightening the nut 19 into the retainer 11, and the pressing force is transmitted to the pump rod 5 via the engagement ring 17. The pump rod 5 is fixed in position with respect to the retainer 11.

[0005]

However, according to the conventional hydraulic shock absorber with the self-pumping mechanism, the pump rod 5 constituting the self-pumping mechanism is used as the connecting means 16 for connecting the retainer 11, that is, the partition member 2. Not only many components such as the mating ring 17, the presser ring 18, the nut 19 and the stopper plate 19a are required, but also a troublesome procedure for crimping the stopper plate 19a to the nut 19 is required, which increases the number of assembly steps and the cost. There was a problem that was inevitable.

The present invention has been made in view of the above-mentioned problems of the prior art. The problem is that the number of parts and the assembly of the pump rod constituting the self-pumping mechanism are necessary for connecting with the partition member. To reduce man-hours as much as possible.

[0007]

In order to achieve the above object, the present invention provides a cylinder in which an oil liquid is sealed, a piston that defines two chambers in the cylinder and has a damping force generating mechanism, and one end. And a hollow piston rod that projects from one end of the cylinder and has the other end connected to the piston, and a reservoir chamber that is connected to a chamber on the other end side of the cylinder via a base valve and compensates for the oil liquid in the cylinder. A hollow pump rod, one end of which is connected to a mounting member provided at the other end of the cylinder and the other end of which is inserted into the piston rod, an oil tank connected to one end of the pump rod, A hydraulic shock absorber provided with a self-pumping mechanism which operates in response to expansion and contraction of a piston rod and lifts oil liquid in the oil tank into a cylinder through the pump rod. The connecting means for connecting the pump rod and the mounting member includes an elastically deformable ring-shaped disc having an inner peripheral edge portion fitted in a circumferential groove provided in the pump rod, and an axially deformable ring-shaped disc for receiving the axial force of the cylinder. The disk is composed of a retainer that presses against the mounting member, and a bending force of the inner peripheral edge of the disk applies a pressing force to the mounting member side to the pump rod.

With this structure, the ring-shaped disc is fitted in the circumferential groove of the pump rod in advance, the retainer is overlapped with the disc and placed on the mounting member, and the cylinder side is assembled. The connection with the member is completed.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings.

1 to 9 show an embodiment of the present invention. As shown in the overall structure of FIG. 4, the hydraulic cylinder according to the present embodiment is provided with a bottomed cylindrical case 21, and the inside of the case 21 is divided into two chambers, an upper chamber and a lower chamber, by a partition member 22 as a mounting member. In the lower chamber (bottom side chamber), an inner cylinder 24 that forms an annular chamber 23 (FIG. 1) with the case 21 is arranged, and a cylinder 26 that forms a reservoir chamber 25 with the case 21 in the upper chamber. Are arranged. A free piston 27 is slidably fitted in the inner cylinder 24. An upper side of the free piston 27 is an oil chamber 28 as an oil tank filled with an oil liquid, and a lower side thereof is filled with a high pressure gas. Each of the gas chambers 29 is configured as a gas chamber 29. In addition, the gas chamber 29 is the inner cylinder 24.
By means of a passage (not shown) provided at the lower end of the annular chamber 2
3, the annular chamber 23 is filled with high-pressure gas.

The lower end of the cylinder 26 has a base valve 30.
And a connecting means 32 for connecting the pump rod 31 to the partition member 22 which will be described later, but abuts against the partition member 22. Then, the inside of the cylinder 26 and the reservoir chamber 25
As shown in FIG. 1, a plurality of oil passages 34 provided in the main body 33 of the base valve 30 and the main body 3 are provided.
3 and the pump rod 31 are communicated with each other by a slight (about 0.5 mm) fitting gap 35. Base valve 30
From the reservoir chamber 25 to the cylinder 2 through the oil passage 34.
It has a check valve 36 that allows the oil liquid to flow into the inside of the valve 6. The check valve 36 is a disc valve 36a that is seated on and separated from the upper surface of the main body 33 of the oil passage 34. The body 33
And a cylinder 36, and a spring 36b is disposed between the cylinder 26 and the cylinder 26, one end of which is in contact with the bottom of the cup member 37 and which normally biases the disc valve 36a in the valve closing direction.

The partition member 22 is provided with an oil passage 38 which connects the inside of the cylinder 26 (reservoir chamber 25) and the oil chamber 28, and a pressure reducing valve 39 is interposed in the oil passage 38. The pressure reducing valve 39 is a valve seat body 4 having a valve seat.
0, and a ball 41 that is seated on or off the valve seat of the valve seat body 40.
And a valve spring (leaf spring) 42 that normally urges the ball 41 in a direction to be seated on the valve seat. When the differential pressure between the cylinder 26 and the oil chamber 28 reaches a predetermined value,
The ball 41 moves away from the valve seat against the biasing force of the valve spring 42, which prevents the oil passage 38 from opening and the pressure in the cylinder 26 from rising excessively.

An annular piston 43 is provided in the cylinder 26.
Is slidably fitted, and the inside of the cylinder 26 is moved by the piston 43 into the cylinder upper chamber 44 and the cylinder lower chamber 4
It is divided into 5 and. As shown in FIG. 5, a substantially cylindrical piston bolt 46 is inserted into the piston 43, and a piston nut 47 is screwed and fixed to the tip of the piston bolt 46. Threaded portion 46 on the upper end side of the piston bolt 46
A lower end portion of a hollow piston rod 48 is screwed into a, and the upper end side of the piston rod 48 is inserted with a sealing device (sealing means) 49, which will be described later, attached to upper end openings of the case 21 and the cylinder 26. Then, it is extended to the outside of the cylinder 26 and the case 21. The cylinder 26 is filled with oil liquid, and the reservoir chamber 25 is filled with oil liquid and high-pressure gas.

In the piston 43, oil passages 50 and 51 for connecting the cylinder upper chamber 44 and the cylinder lower chamber 45 to each other.
And a normally closed disc valve 52 (damping force generating mechanism) that is bent by a predetermined pressure on the cylinder upper chamber 44 side to allow the oil liquid in one of the oil passages 50 to flow to generate a damping force. There is. A notch 53 that forms an orifice passage (a damping force generating mechanism) is provided in the valve seat portion of the disc valve 52, and the notch 53 always communicates between the cylinder upper and lower chambers 44 and 45. Also, piston 4
3 is a normally closed disc valve 54 (damping force generating mechanism) which is bent by a predetermined pressure on the cylinder lower chamber 45 side to allow the oil liquid in the compression side passage 51 to flow and generate a damping force.
Is also provided.

As shown in FIG. 6, the sealing device 49 is fitted into the cylinder 26 and is fitted with a piston rod 48.
Rod guide 55 that slidably guides the case 21
And an intermediate ring 56 fitted to the piston rod 48 and pressing the rod guide 55 from above, and a tightening ring 5 screwed to the case 21 to press the intermediate ring 56 from above.
7 is provided. By tightening the tightening ring 57 into the case 21, the tightening force is transmitted to the cylinder 26 via the intermediate ring 56 and the rod guide 55, and the cylinder 26 is abutted against the partition member 22 with a predetermined axial force. Will be done.

An O-ring 58 for gas sealing and first and second sealing members 59, 60 for rod sealing are provided between the rod guide 55, the intermediate ring 56 and the tightening ring 57. A gas seal and an oil relief check valve 61 are supported. The first seal member 59 for rod seal is formed of a polytetrafluoroethylene ring having good sliding characteristics, and the second seal member 60 is formed of a rubber oil seal having good sealing properties. In particular, the seal member 60 of the check valve portion 6 that closes the escape passage 62 formed in the intermediate ring 56.
3 are provided integrally. This check valve unit 63 is
Although the oil liquid leaking from the cylinder upper chamber 44 is allowed to flow to the reservoir chamber 23, the gas in the reservoir chamber 23 is between the first seal member 59 and the second seal member 60, and the cylinder upper chamber 44. It plays a role of controlling the flow to.

On the other hand, inside the piston rod 48, a large diameter portion 64a and a small diameter portion 64 which are slightly smaller in diameter than the hollow portion 48a thereof.
A stepped pump tube 64 consisting of b and b is inserted. The upper end of the piston rod 48 is closed, and the pump tube 64 has its end on the small diameter portion 64b side pressed by the holding spring 65 near the closed end of the piston rod 48, as shown in FIG. The end on the large diameter portion 64a side is brought into contact with the piston bolt 46 to be fixed in position (FIG. 5). An annular oil passage 66 is formed between the inner surface of the piston rod 48 and the pump tube 64,
It communicates with the cylinder upper chamber 44 through an opening 67 (FIG. 5) provided in the side wall of the piston rod 48.

The tip side of the pump rod 31 connected to the partition member 22 via a connecting means 32 has a cylinder 26.
Of the pump tube 64, the piston tube 46 is inserted into the large diameter portion 64a of the pump tube 64, and the small diameter portion 64b is slidably fitted therein. A pump chamber 68 is formed on the upper side in the small diameter portion 64b of the pump tube 64 by the tip of the pump rod 31, and the pump chamber 68 has a through hole for the passage 31a in the pump rod 31 and the partition member 22. An oil passage 69 constituted by 22a communicates with the oil chamber 28 (FIG. 1).

At the upper end of the small diameter portion 64b of the pump tube 64, there is provided a check valve 70 which allows only the flow of the oil liquid from the pump chamber 68 to the oil passage 66 (FIG. 7). A check valve 71 is provided at the tip of the rod 31 to allow only the flow of the oil liquid from the oil chamber 18 to the pump chamber 68 through the oil passage 69 (FIG. 8). The check valve 70, as best shown in FIG.
The small-diameter portion 64 is formed by a valve spring 73 whose one end is locked to a substantially U-shaped retainer 72 fixed to the tip of the small-diameter portion 64b of No. 4 of FIG.
The valve body 74 is pushed to the open end of the valve b, and the valve body 74 is pushed up from the open end of the small diameter portion 64b against the elastic force of the valve spring 73 by the pressure on the pump chamber 68 side to open. I'm supposed to speak. In the figure, reference numeral 75 is a stopper that restricts the movement of the valve body 64. On the other hand, pump rod 3
As shown in FIG. 5, the check valve 71 at the front end of No. 1 is attached to the open end of the pump rod 31 by a valve spring 77 whose one end is locked to a substantially U-shaped retainer 76 fixed to the front end of the pump rod 31. It is provided with a pressed valve body 78, and the valve body 78 is pressed by the pressure on the oil passage 69 side communicating with the oil chamber 18.
Is pushed up from the open end of the pump rod 31 against the elastic force of the valve spring 77 to open the valve.

An annular passage 79 communicating with the lower cylinder chamber 45 is formed between the piston rod 46 and the large diameter portion 64a of the pump tube 64 and the pump rod 31 (FIG. 5). Further, the pump rod 31 is formed with a notch 80 extending axially from a tip end fitted to the pump tube 64 to a predetermined portion, and the notch 80 causes the pump rod 31 and the small diameter portion 64 of the pump tube 64 to be formed.
A liquid passage 81 is formed between it and b (FIG. 5). The cutout 80 overlaps only the small diameter portion 64b of the pump tube 64 when the extension length of the piston rod 48 is shorter than a predetermined standard range (when it is shorter than the first predetermined position which is the lower limit of the standard range), and the large diameter portion is formed. The communication between the liquid passage 81 and the annular passage 79 is cut off at a position not overlapping the 64a. Further, when the piston rod 48 extends to the predetermined standard range (when it extends to the first predetermined position which is the lower limit of the standard range), the pump tube 64 moves together with the piston rod 48 and the large diameter portion 64a becomes the notch 80. When overlapped, the liquid passage 81 is communicated with the annular passage 79 and the cylinder upper / lower chamber 4
It is designed to communicate with 4,45.

Further, on the side wall of the pump rod 31, there is provided an orifice passage 82 penetrating from the oil passage 69 to the wall surface (FIG. 5). The orifice passage 82 has a cutout 8
0 is arranged at a portion closer to the pump chamber 68 with respect to the lower end, and is located at a position overlapping the small diameter portion 64b of the pump tube 64 when the extension length of the piston rod 48 is within a predetermined standard range, and the orifice Passage 82 and circular passage 79
Communication with is interrupted. Also, the piston rod 48
When the extension length of the cylinder exceeds the predetermined standard range, the orifice passage 82 overlaps with the large diameter portion 64a of the pump tube 64, the orifice passage 82 communicates with the annular passage 79, and the upper and lower chambers 26, 27 of the cylinder are communicated. It is designed to communicate with. Reference numeral 83 is a rebound stopper that is mounted on the piston rod 48.

As shown in FIG. 1, the pump rod 31 has its base end portion loosely inserted into the main body 33 of the base valve 30 and extended to the partition member 22 side.
It is fitted in the concave portion 84 provided in 2. Connecting means 32 for connecting the pump rod 31 to the partition member 22
Is an elastically deformable ring-shaped disc 91 whose inner peripheral edge is fitted in a circumferential groove 90 provided in the pump rod 31, and the disc 91 by receiving the axial force of the cylinder 26 via the main body 33 of the base valve 30. The mounting surface 22b of the partition member 22
It is composed of a ring-shaped retainer 92 that is pressed against.

The pump rod 31 is fixed in position by inserting its base end into the recess 84 of the partition member 22 until it bottoms out. In this fixed position, the pump rod 3 is fixed.
1 of the peripheral groove 90 and the mounting surface 22b of the partition member 22
A step having a predetermined size δ is formed between and. Then, a stepped escape portion 93 is formed on the lower surface of the retainer 92 on the inner peripheral side, and the disc 91
The inner peripheral edge portion is bent inside the escape portion 93 and is sandwiched between the partition member 22 and the retainer 92. That is, due to the bending of the disc 91, a pressing force from the disc 91 to the partition member 22 side, that is, a predetermined set load is applied to the pump rod 31. This set load is set to a value equal to or more than the tensile force applied to the pump rod 31 during the extension stroke of the piston rod 48, and therefore the disc 91 does not play in the circumferential groove 90 of the pump rod 31.

As shown in FIG. 2 as an example, the disc 91 has a central hole 94A smaller in diameter than the pump rod 31.
And a plurality of circumferential notches 94B located on the outer peripheral side and intermittently provided in the circumferential direction, and a plurality of radial notches 94C connecting the circumferential notches 94B and the central hole 91A. The claw piece 95 is provided, and the set load is generated by elastic deformation of the claw piece 95. To assemble the disc 91 to the pump rod 31, for example, as shown in FIG. 3, a thin-walled cap 96 is fitted in advance to the tip of the pump rod 31 (), and the tapered portion 96a at the tip of the cap 96 is used. Then, the disk 91 can be pushed up to fit into the circumferential groove 90 of the pump rod 31.

The disc 91 is assembled on the pump rod 31 in advance as described above, and then the retainer 92 and the base valve 30 are placed on the disc 91 and placed on the partition member 22. After that, when the cylinder 26 and the like are assembled and the assembly as a hydraulic shock absorber is completed, the disk 91 is sandwiched between the partition member 22 and the retainer 92 by the axial force applied to the cylinder 26, and as described above, the pump rod 31. A set load is applied to. The plate thickness of the disc 91 is sufficiently thinner than the width of the circumferential groove 90 of the pump rod 31 in consideration of the assembling property. However, in the assembled state of the hydraulic shock absorber, the disc 91 is set in the circumferential groove 90 by the set load. The play of the disc 91 is eliminated, so that no rattling noise is generated during operation.

The pump rod 31 is allowed to tilt in the radial direction during operation by the fitting gap 35 with the main body 33 of the base valve 30. Further, in the recess 84 of the partition member 22, the partition member 22 and the pump rod 3
Although an O-ring 97 and a backup ring 98 for sealing between the O-ring 97 and the No. 1 are arranged, the O-ring 97 of the backup ring 98 is deformed by the pressure difference between the inside of the cylinder 26 and the oil chamber 28, and the partition member. It is made of resin and has a role of preventing damage to the fitting gap 22 between the pump rod 31 and the pump rod 31.

In this hydraulic shock absorber, the upper end of the piston rod 48 is connected to the vehicle body side (not shown), and the lower end of the case 21 is connected to the wheel side (not shown).
As shown in FIG. 4, a wheel mounting bracket 100 is attached to the lower end of the case 21 and a suspension spring (not shown) is attached to the upper end of the case 21 as shown in FIG. The spring receivers 101 to be received are fixed.

The operation of the embodiment configured as described above will be described below.

During the extension stroke of the piston rod 48, the oil liquid on the cylinder upper chamber 44 side is pressurized as the piston 43 moves, and this pressure oil flows through the oil passage 50 to the cylinder lower chamber 45 side, and the notch 53 The damping force is generated by the orifice formed by. At this time, as shown in the right half of FIG. 9, the oil liquid that the piston rod 48 withdraws from the cylinder 26 passes from the reservoir chamber 25 through the oil passage 34 of the base valve 30 due to the expansion of the gas, and then the check valve 36. Is opened to replenish the lower cylinder chamber 45, and at the same time, it is replenished through the fitting gap 35 between the pump rod 31 and the main body 33 of the base valve 30. Further, when the piston speed increases and the hydraulic pressure on the cylinder upper chamber 44 side reaches a predetermined pressure, the disc valve 52 opens to suppress an excessive increase in the damping force.

On the other hand, during the compression stroke of the piston rod 48, the oil liquid on the cylinder lower chamber 45 side is pressurized with the movement of the piston 43 and passes through the oil passage 50 to cause the cylinder upper chamber 4 to move.
A damping force is generated by the orifice formed by the notch 53 and flowing toward the 4th side. At this time, as much oil as the piston rod 48 has entered the cylinder 26, as shown in the left half of FIG. 9, the pump rod 31 and the main body 3 of the base valve 30.
Gas is compressed by flowing into the reservoir chamber 25 through the fitting gap 35 with the gas. When the piston speed increases and the hydraulic pressure in the cylinder lower chamber 45 reaches a predetermined pressure, the disc valve 54 opens to allow the oil liquid to flow through the contraction side passage 51, thereby suppressing an excessive increase in the damping force.

Next, the vehicle height adjusting function of the hydraulic shock absorber 1 will be described. When the vehicle is empty (at a standard vehicle height), the gas chamber 29 and the reservoir chamber 25 on the bottom side have the same pressure, and the extension length of the piston rod 48 is within a predetermined standard range. In this state, the notch 80 of the pump rod 31 overlaps with the large diameter portion 64a of the pump tube 64, the pump chamber 68 communicates with the cylinder upper and lower chambers 26 and 27 through the liquid passage 81 and the annular passage 79, and the pumping action is performed. Is not done.

When the vehicle load increases and the vehicle height becomes lower than the standard vehicle height, and the extension length of the piston rod 48 becomes shorter than the standard range, the notch 80 of the pump rod 31 becomes a small diameter portion of the pump tube 64. 64b is overlapped and closed. In this state, when the piston rod 48 expands and contracts due to the vibration of the suspension device during traveling, during the extension stroke, the pump rod 31 in the small diameter portion 64b of the pump tube 64 retracts, and the pressure in the pump chamber 68 decreases. The check valve 71 opens and the oil passage 1 passes through the oil passage 69.
8 is introduced into the pump chamber 68, and during the compression stroke, the pump rod 31 moves forward to pressurize the pump chamber 68, the check valve 70 opens, and the oil liquid in the pump chamber 68 is released. Is supplied to the cylinder upper chamber 44 through the oil passage 66 around the pump tube 64 and the opening 67 of the piston rod 48 to pressurize the cylinder upper / lower chambers 44 and 45 and the reservoir chamber 25 to extend the piston rod 48. Let
In this way, the vehicle height is increased by repeating the pumping operation by utilizing the vibration during traveling. When the vehicle height reaches the standard vehicle height and the extension length of the piston rod falls within the standard range, the notch 80 of the pump rod 31 overlaps with the large diameter portion 64a of the pump tube 64, and the pump chamber 68 is above the cylinder. The lower chambers 44 and 45 are communicated with each other and the pumping operation is released.

Further, when the vehicle load decreases and the vehicle height becomes higher than the standard vehicle height, and the extension length of the piston rod 48 becomes longer than the standard range, the notch 80 of the pump rod 31 and the orifice passage 82 are formed. The pump chamber 68 overlaps with the large diameter portion 64a of the pump tube 64, the pump chamber 68 communicates with the cylinder upper and lower chambers 44 and 45 to release the pumping operation, and the cylinder upper and lower chambers 44 and 45 are connected to the annular passage 79.
And the oil passage 69 in the pump rod 31 via the orifice passage 82, and the cylinder upper / lower chambers 44, 45
The pressure oil inside is returned to the oil chamber 18, and the cylinder upper / lower chambers 44 and 45 and the reservoir chamber 25 are decompressed and the vehicle height is lowered. The vehicle height drops to the standard vehicle height and the piston rod 48
When the extension length of the pump rod 31 falls within the standard range, the orifice passage 82 of the pump rod 31 becomes smaller than the small diameter portion 64 of the pump tube 64.
It is closed by overlapping with b, and the returning operation of the pressure oil in the cylinder upper / lower chambers 44 and 45 is stopped.

As described above, the vehicle height can be adjusted to be constant regardless of the load by repeating the pumping action and the returning action by utilizing the vibration of the suspension system during traveling.

By the way, during the compression stroke of the piston rod 48 and during the pumping operation, the cylinder upper / lower chamber 4
The hydraulic pressure of 4, 45 rises, and the oil liquid tries to leak from the sealing device 49. However, in the present embodiment, since the rod seals are provided in two stages, even if oil leakage occurs from the first seal member 59 that emphasizes sliding characteristics, the second seal made of a rubber oil seal is used. The member 60 prevents leakage to the outside. Further, when the pressure of the leaked oil rises, the check valve portion 63 of the second seal member 60 opens, and the oil liquid flows into the reservoir chamber 25 through the escape passage 62. Spillage is completely prevented. Moreover, in this embodiment, the pressure reducing valve 3 is attached to the partition member 22.
9 is provided, when the pressure in the cylinder upper / lower chambers 44, 45 rises extremely, the pressure reducing valve 39 opens and the oil liquid in the cylinder 26 flows out to the lower oil chamber 28, which is more safe. It has been secured.

In the above embodiment, the case where the reservoir chamber 25, the cylinder 26, and the oil chamber 28 as an oil tank are provided in the case 21 has been shown, but the present invention is not limited to this, and for example, an oil chamber may be provided. It may be provided separately from the case 21, and the oil chamber and the through hole 22a of the partition member 21 may be connected by piping.

[0037]

As described above in detail, according to the hydraulic shock absorber of the present invention, the disc is fitted in the circumferential groove of the pump rod which constitutes the pumping mechanism, and the axial force for generating the disc in the cylinder is provided. The pump rod can be assembled by a simple means of pressing by the receiving retainer, the number of parts and the number of assembling steps can be reduced, and a significant cost reduction can be achieved. Further, since the set load is applied to the pump rod by utilizing the flexure of the disc, it is possible to prevent the abnormal noise from being generated due to the rattling of the pump rod, and the utility value thereof is generally high.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a main structure of a hydraulic shock absorber according to the present invention.

FIG. 2 is a plan view showing an example of the shape of a disk that constitutes the connecting means of the present invention.

FIG. 3 is a front view showing an assembling method and an assembling state of a disc with respect to a pump rod.

FIG. 4 is a sectional view showing the overall structure of the present hydraulic shock absorber.

FIG. 5 is a cross-sectional view showing a piston portion of the hydraulic shock absorber and a structure around the piston portion.

FIG. 6 is a cross-sectional view showing a seal structure of the present hydraulic shock absorber.

FIG. 7 is a cross-sectional view showing a check valve of a pump tube and a structure around it.

FIG. 8 is a cross-sectional view showing a check valve of a pump rod and a structure around it.

FIG. 9 is a cross-sectional view showing an operating state of a main part of the hydraulic shock absorber.

FIG. 10 is a cross-sectional view showing a connection structure between a pump rod and a partition member of a conventional hydraulic shock absorber.

[Explanation of symbols]

 21 Case 22 Partition Member 25 Reservoir Chamber 26 Cylinder 28 Oil Chamber (Bottom Side Chamber) 30 Base Valve 31 Pump Unit 32 Connecting Means 36 Check Valve 43 Piston 48 Piston Rod 49 Seal Device (Seal Means) 52 Disc Valve (Damping Force Generating Mechanism) ) 53 orifice passage (damping force generating mechanism) 64 pump tube 68 pump chamber 70 pump tube check valve 71 pump rod check valve 90 pump rod circumferential groove 91 disc 92 retainer

Claims (1)

[Claims] 1. A cylinder in which an oil liquid is sealed, a piston having two chambers defining the inside of the cylinder and having a damping force generating mechanism, one end protruding from one end of the cylinder, and the piston connected to the other end. Hollow piston rod, a reservoir chamber that is connected to a chamber on the other end side of the cylinder via a base valve to compensate for oil liquid in the cylinder, and one end of a mounting member provided on the other end of the cylinder. Is connected and the other end is inserted into the piston rod, a hollow pump rod, an oil tank connected to one end of the pump rod, and the piston rod is actuated in response to expansion and contraction of the piston rod. In a hydraulic shock absorber provided with a self-pumping mechanism for pumping the oil liquid in the oil tank into a cylinder, a coupling hand for coupling the pump rod and the mounting member. The step is composed of an elastically deformable ring-shaped disc whose inner peripheral edge portion is fitted in a circumferential groove provided in the pump rod, and a retainer that receives the axial force of the cylinder and presses the disc against the mounting member. A hydraulic shock absorber, wherein a pressing force to the mounting member side is applied to the pump rod by bending of an inner peripheral edge portion of the disk.