JP4022658B2 - Hydraulic shock absorber - Google Patents

Description

  The present invention relates to a hydraulic shock absorber mounted on a suspension device such as an automobile, and more particularly to a hydraulic shock absorber having a built-in self-pumping mechanism that controls the extension length of a piston rod within a certain range.

  In this type of hydraulic shock absorber, a bottomed cylindrical case is partitioned into two chambers by a partition member, and an oil solution is sealed in a bottom side chamber (oil tank) of the case, and an oil is stored in a chamber on the opening side. A cylinder filled with liquid is disposed, and the reservoir chamber around the cylinder communicates with the cylinder through a base valve disposed between the cylinder and the partition member, and a damping force is applied to the cylinder. A piston having a generating mechanism is slidably mounted, and a base end portion of a hollow piston rod extending through the sealing means attached to the case and the opening of the cylinder to the outside of the cylinder is provided in the piston. Further, in the piston rod, it operates according to the expansion and contraction of the piston rod, and through the pump rod extending from the partition member into the piston rod, the bottom side of the case There is an oil solution of the inner ones were provided with self-pumping mechanism to raise in the cylinder.

  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 constituting a self-pumping mechanism, and an inner chamber (lower chamber) 6 of the cylinder 3 and its surroundings. The reservoir chamber 7 is communicated with an oil passage 8 provided in the main body 4a of the base valve 4, and the internal passage 9 of the pump rod 5 and the bottom side chamber (oil tank) 10 of the case 1 are connected to the partition member 2 and the base valve. 4 is communicated with the through hole 12 of the retainer 11 interposed between the main body 4a. The base valve 4 has a check valve 13 that allows oil to flow from the reservoir chamber 7 to the cylinder lower chamber 6 through the oil passage 8 and an orifice 14 that allows the oil passage 8 to always communicate.

  The pump rod 5 is slidably fitted into a spherical concave hole 11 a provided in the retainer 11 so that the radial tilt during operation is allowed, and the retainer is connected by the connecting means 16. 11 is fixed in position. The connecting means 16 includes an engagement ring 17 that fits into an annular groove provided on the peripheral surface of the pump rod 5, a presser ring 18 that presses the outer surface of the engagement ring 17, and a nut 19 that is screwed into the retainer 11. The stopper plate 19a is caulked and stopped. According to such connecting means 16, the stopper plate 17 a presses the back surface of the presser ring 18 by tightening the nut 19 into the retainer 11, and the presser force is transmitted to the pump rod 5 through the engagement ring 17. The position of the pump rod 5 is fixed with respect to the retainer 11. Further, a seal member A that seals between the cylinder lower chamber 6 and the oil tank 10 is provided between the pump rod 5 and the retainer 11.

  However, according to the conventional hydraulic shock absorber with a self-pumping mechanism, the seal member A between the pump rod 5 and the retainer 11 constituting the self-pumping mechanism has a pressure in the chamber in the cylinder 3 where the pressure is highest. It is necessary to seal a portion with a large differential pressure between the low bottom side chambers 10 (oil tanks). Further, since the pump rod 5 is allowed to tilt in the radial direction during operation, this seal is quite difficult. There was a problem.

In order to solve the above problems, the present invention provides a cylinder in which oil is sealed, a case that is provided on the outer periphery of the cylinder and forms a reservoir chamber between the cylinder, and is slidable in the cylinder. A piston that is fitted and defines the inside of the cylinder in two chambers, and one end connected to the piston and the other end extended to the outside via a guide member that closes the case and the other end of the cylinder A hollow piston rod; a base valve main body having an oil passage communicating the inside of the cylinder and the reservoir chamber; a valve provided in the base valve main body for controlling the flow of oil in the oil passage; and an oil chamber transmural and the oil tank and a gas chamber, and a partition member for isolating the one end of the reservoir chamber and said base valve body in the case and the oil tank, one end of the base valve body While connecting the oil chamber of the engage and the oil tank to said partition member and being tiltably connected to the partition member, a hollow pump rod the other end is inserted into the piston rod, A gap formed between the pump rod and the base valve body to allow the pump rod to tilt, and between the partition member and the pump rod to seal between the cylinder and the oil tank . A seal member provided therebetween and a self-pumping mechanism that operates according to the expansion and contraction of the piston rod and lifts the oil in the oil tank into the cylinder through the pump rod are provided. .

  Further, a gap is provided in the pump rod penetrating portion of the base valve main body, and a passage communicating with the reservoir chamber is formed between the base valve main body and the partition member, and the inside of the cylinder is interposed via the passage and the gap. And the reservoir chamber are communicated with each other.

According to the hydraulic shock absorber of the present invention, the pump rod penetrates the base valve body and is tiltably connected to the partition member, and the oil tank is connected to one end side of the pump rod. Since the pressure in the intense cylinder and the pressure in the low-pressure oil tank are not directly sealed, sealing becomes easy.
According to the second aspect of the present invention, the pressure between the cylinder and the partition member is the pressure in the reservoir chamber, and the cylinder, the reservoir chamber, and the oil tank are arranged in order from the higher pressure. Easy and reliable.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  1 to 9 show an embodiment of the present invention. As shown in FIG. 4, the hydraulic cylinder according to the present embodiment includes a bottomed cylindrical case 21, and the inside of the case 21 is partitioned into two upper and lower chambers by a partition member 22 as an attachment member. An inner cylinder 24 that forms an annular chamber 23 (FIG. 1) between the lower chamber (bottom side chamber) and the case 21 is disposed, and a cylinder 26 that forms a reservoir chamber 25 between the upper chamber and the case 21. Is arranged. A free piston 27 is slidably fitted in the inner cylinder 24. An upper side of the free piston 27 serves as an oil chamber 28 serving as an oil tank filled with an oil liquid, and a lower side thereof is filled with high-pressure gas. The gas chambers 29 are respectively configured. The gas chamber 29 is communicated with the annular chamber 23 by a passage (not shown) provided at the lower end portion of the inner cylinder 24, and the annular chamber 23 is filled with high-pressure gas.

  The lower end of the cylinder 26 is abutted against the partition member 22 via a base valve 30 and a connecting means 32 for connecting a pump rod 31 described later to the partition member 22. As shown in FIG. 1, the cylinder 26 and the reservoir chamber 25 are divided into a plurality of oil passages 34 provided in a main body (base valve main body) 33 of the base valve 30, and the main body 33 and the pump rod 31. The small gap (about 0.5 mm) of the fitting gap 35 and the passage F formed between the main body 33 and the partition member 22 are communicated. The base valve 30 has a check valve (valve) 36 that allows oil to flow from the reservoir chamber 25 into the cylinder 26 through the oil passage 34. The check valve 36 is a disc valve 36 a that is seated on the upper surface of the main body 33 of the oil passage 34. One end is brought into contact with the bottom of the cup member 37 interposed between the main body 33 and the cylinder 26, and the spring 36b normally biases the disc valve 36a in the valve closing direction.

  The partition member 22 is provided with an oil passage 38 communicating 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 includes a valve seat body 40 on which a valve seat is formed, a ball 41 that is detachably seated on the valve seat of the valve seat body 40, and a valve that urges the ball 41 in a direction in which the ball 41 is normally seated on the valve seat. When the pressure difference between the cylinder 26 and the oil chamber 28 reaches a predetermined value, the ball 41 separates from the valve seat against the urging force of the valve spring 42 and As a result, the oil passage 38 is opened to prevent the pressure in the cylinder 26 from rising excessively.

  An annular piston 43 is slidably fitted in the cylinder 26, and the inside of the cylinder 26 is partitioned into a cylinder upper chamber 44 and a cylinder lower chamber 45 by the piston 43. As shown well 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 portion thereof. The lower end portion of the hollow piston rod 48 is screwed to the screw portion 46 a on the upper end side of the piston bolt 46, and the upper end side of the piston rod 48 is attached to the upper end openings of the case 21 and the cylinder 26, which will be described later. The seal device (sealing means) 49 is inserted and extended to the outside of the cylinder 26 and the case 21. An oil liquid is sealed in the cylinder 26, and an oil liquid and a high-pressure gas are sealed in the reservoir chamber 25.

  The piston 43 is bent by oil passages 50 and 51 that allow the cylinder upper chamber 44 and the cylinder lower chamber 45 to communicate with each other and a predetermined pressure on the cylinder upper chamber 44 side, and permits the fluid of one oil passage 50 to flow. And a normally closed disk valve 52 (a damping force generating mechanism) for generating a damping force. The valve seat portion of the disc valve 52 is provided with a notch 53 that forms an orifice passage (a damping force generating mechanism), and the upper and lower chambers 44 and 45 are always in communication with each other by the notch 53. The piston 43 is also provided with a normally closed disk valve 54 (a damping force generation mechanism) that is bent by a predetermined pressure on the cylinder lower chamber 45 side and allows a fluid flow in the contraction side passage 51 to generate a damping force. Is provided.

  As shown well in FIG. 6, the sealing device 49 is fitted to a rod guide (guide member) 55 that is fitted to the cylinder 26 and slidably guides the piston rod 48, and the case 21 and the piston rod 48. An intermediate ring 56 that presses the rod guide 55 from above and a tightening ring 57 that is screwed into the case 21 and presses the intermediate ring 56 from above. By tightening the tightening ring 57 into the case 21, the tightening force is transmitted to the cylinder 26 through the intermediate ring 56 and the rod guide 55, and the cylinder 26 abuts against the partition member 22 with a predetermined axial force. Will be.

  Between the rod guide 55, the intermediate ring 56 and the tightening ring 57, a gas seal O-ring 58, first and second seal members 59 and 60 for rod seal, and a gas seal are provided. An oil release check valve 61 is supported. The first seal member 59 for the rod seal is formed from a polytetrafluoroethylene ring having good sliding characteristics, and the second seal member 60 is formed from a rubber oil seal having good sealability. In particular, the seal member 60 is integrally provided with a check valve portion 63 for closing a relief passage 62 formed in the intermediate ring 56. The check valve portion 63 allows the fluid leaking from the cylinder upper chamber 44 to flow into the reservoir chamber 23, but the gas in the reservoir chamber 23 flows between the first seal member 59 and the second seal member 60. It plays a role of regulating the flow into the cylinder upper chamber 44.

  On the other hand, a stepped pump tube 64 composed of a large diameter portion 64a and a small diameter portion 64b that are slightly smaller in diameter than the hollow portion 48a is inserted into the piston rod 48. 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 well shown in FIG. The end of the large diameter portion 64a is brought into contact with the piston bolt 46 and 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, and communicates with the cylinder upper chamber 44 through an opening 67 (FIG. 5) provided on the side wall of the piston rod 48. Yes.

  The distal end side of the pump rod 31 connected to the partition member 22 via the connecting means 32 is extended along the axis of the cylinder 26 and is inserted into the large diameter portion 64a of the pump tube 64 through the piston bolt 46. Further, it is inserted into the small diameter portion 64b so as to be slidable. 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 passage 31a in the pump rod 31 and a through hole in the partition member 22. The oil chamber 69 communicates with the oil chamber 28 by an oil passage 69 constituted by 22a (FIG. 1).

  At the upper end of the small diameter portion 64b of the pump tube 64, there is provided a check valve 70 that allows only the flow of oil from the pump chamber 68 to the oil passage 66 (FIG. 7). At the tip, a check valve 71 is provided that allows only the flow of oil from the oil chamber 18 to the pump chamber 68 through the oil passage 69 (FIG. 8). As shown well in FIG. 7, the check valve 70 has an opening in the small diameter portion 64 b by a valve spring 73 whose one end is locked to a substantially U-shaped retainer 72 fixed to the distal end portion of the small diameter portion 64 b of the pump tube 64. The valve body 74 is held at the end, and the valve body 74 is pushed up from the opening 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 the valve. It has become. In the figure, reference numeral 75 denotes a stopper for restricting the movement of the valve body 64. On the other hand, as shown in FIG. 5, the check valve 71 at the tip of the pump rod 31 is pump rod 31 by a valve spring 77 whose one end is locked to a substantially U-shaped retainer 76 fixed to the tip of the pump rod 31. The valve body 78 is held by the opening end of the pump rod 31 from the opening end of the pump rod 31 against the elastic force of the valve spring 77 by the pressure on the oil passage 69 side communicating with the oil chamber 18. The valve is pushed up to open. The pump rod 31, the pump tube 64, the pump chamber 68, the check valves 70 and 71, etc. constitute a self-pumping mechanism.

  An annular passage 79 communicating with the cylinder lower chamber 45 is formed between the piston bolt 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 from the tip end fitted to the pump tube 64 to a predetermined portion in the axial direction, and the notch 80 allows the pump rod 31 and the small diameter portion 64b of the pump tube 64 to be connected. A liquid passage 81 is formed between them (FIG. 5). 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 that is the lower limit of the standard range), the notch 80 overlaps only with the small diameter portion 64b of the pump tube 64, and the large diameter portion The communication between the liquid passage 81 and the annular passage 79 is cut off at a position that does not overlap with 64a. When the piston rod 48 extends to a predetermined standard range (when the piston rod 48 extends to the first predetermined position that 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. Overlappingly, the liquid passage 81 is communicated with the annular passage 79 so as to communicate with the cylinder upper / lower chambers 44 and 45.

  Further, an orifice passage 82 penetrating from the oil passage 69 to the wall surface is provided on the side wall of the pump rod 31 (FIG. 5). The orifice passage 82 is disposed at a position near the pump chamber 68 with respect to the lower end of the notch 80, and when the extension length of the piston rod 48 is not more than a predetermined standard range, the small diameter portion 64b of the pump tube 64 is provided. And the communication between the orifice passage 82 and the annular passage 79 is blocked. When the extension length of the piston rod 48 exceeds a predetermined standard range, the orifice passage 82 overlaps the large diameter portion 64a of the pump tube 64, and the orifice passage 82 is communicated with the annular passage 79 so that the The lower chambers 26 and 27 are communicated with each other. Reference numeral 83 denotes a rebound stopper externally mounted on the piston rod 48.

  Here, as shown well in FIG. 1, the pump rod 31 has a base end portion that is loosely inserted into the main body 33 of the base valve 30 and extends toward the partition member 22, and is inside a recess 84 provided in the partition member 22. Is inserted. The connecting means 32 for connecting the pump rod 31 to the partition member 22 includes an elastically deformable ring-shaped disk 91 having an inner peripheral edge fitted in a circumferential groove 90 provided in the pump rod 31, and a shaft of the cylinder 26. The ring-shaped retainer 92 is configured to receive a force through the main body 33 of the base valve 30 and press the disk 91 against the mounting surface 22 b of the partition member 22.

  The position of the pump rod 31 is fixed by fitting the base end of the pump rod 31 into the recess 84 of the partition member 22 until it is bottomed. In this position fixed state, the pump rod 31 and the lower wall surface of the circumferential groove 90 of the pump rod 31 are fixed. A step having a predetermined size δ is formed between the partition member 22 and the mounting surface 22b. Accordingly, a stepped relief portion 93 is formed on the lower surface on the inner peripheral side of the retainer 92, and the disk 91 is bent with its inner peripheral edge portion into the relief portion 93, and the partition member 22, the retainer 92, Is sandwiched between. That is, due to the bending of the disk 91, a pressing force from the disk 91 toward the partition member 22, that is, a predetermined set load is applied to the pump rod 31. This set load is set to a value equal to or greater than the tensile force applied to the pump rod 31 during the extension stroke of the piston rod 48, so that the disk 91 does not play in the circumferential groove 90 of the pump rod 31.

  As shown in FIG. 2 as an example, the disk 91 includes a center hole 94A having a smaller diameter than the pump rod 31, a circumferential notch 94B located on the outer circumferential side and provided intermittently in the circumferential direction, It has a plurality of claw pieces 95 divided by a circumferential cutout 94B and a radial cutout 94C connecting the central hole 91A, and the set load is generated by elastic deformation of the claw pieces 95. ing. In order to assemble the disk 91 to the pump rod 31, for example, as shown in FIG. 3, a thin cap 96 is fitted in advance to the tip of the pump rod 31 ((1)), and the tapered portion of the tip of the cap 96 is attached. A method of pushing up the disk 91 using 96a and fitting it into the circumferential groove 90 of the pump rod 31 ((2)) can be employed.

  As described above, the disk 91 is mounted on the partition member 22 with the retainer 92 and the base valve 30 superimposed thereon after being assembled to the pump rod 31 in advance. Thereafter, when the cylinder 26 or the like is assembled and the assembly as the 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 the pump rod 31 as described above. A set load is applied. The thickness of the disk 91 is sufficiently smaller 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 thickness of the disk 91 in the circumferential groove 90 is increased. The play of the disk 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 between the base valve 30 and the main body 33. Further, an O-ring (seal member) 97 and a backup ring 98 for sealing between the partition member 22 and the pump rod 31 are disposed in the recess 84 of the partition member 22. The O-ring 97 is deformed by the pressure difference between the cylinder 26 and the oil chamber 28 and prevents the O-ring 97 from entering into the fitting gap between the partition member 22 and the pump rod 31 and being damaged. Has been. The pressure applied to the O-ring 97 is a differential pressure between the reservoir chamber 25 and the oil chamber 28.

  The hydraulic shock absorber is mounted as a vehicle suspension device by connecting the upper end of the piston rod 48 to the vehicle body (not shown) and the lower end of the case 21 to the wheel (not shown). As shown in FIG. 4, a bracket 100 for mounting on the wheel side is fixed to the lower end portion of the case 21, and a spring receiver 101 for receiving a suspension spring (not shown) is fixed to the upper end portion of the case 21, respectively. ing.

  Hereinafter, the operation of the embodiment configured as described above will be described.

  During the extension stroke of the piston rod 48, the hydraulic fluid on the cylinder upper chamber 44 side is pressurized with the movement of the piston 43, and this pressurized oil flows to the cylinder lower chamber 45 side through the oil passage 50 to form a notch 53. A damping force is generated by the orifice. At this time, as shown in the right half of FIG. 9, the oil liquid corresponding to the withdrawal of the piston rod 48 from the cylinder 26 passes through the oil passage 34 of the base valve 30 from the reservoir chamber 25 due to gas expansion, and then the check valve 36. Is supplied to the cylinder lower chamber 45, and at the same time, it is supplied 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 damping force.

  On the other hand, during the contraction 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, flows through the oil passage 50 to the cylinder upper chamber 44 side, and is formed by the orifice formed by the notch 53. Damping force is generated. At this time, the oil liquid that the piston rod 48 has entered into the cylinder 26 is separated from the fitting gap 35 between the pump rod 31 and the main body 33 of the base valve 30 and the main body 33 as shown in the left half of FIG. It flows into the reservoir chamber 25 through the passage F between the member 22 and compresses the gas. Further, when the piston speed increases and the hydraulic pressure in the cylinder lower chamber 45 reaches a predetermined pressure, the disc valve 54 is opened to allow the oil liquid to flow through the contraction side passage 51, thereby suppressing an excessive increase in damping force.

Next, the vehicle height adjustment function of the hydraulic shock absorber 1 will be described.
When the vehicle is empty (standard vehicle height), the gas chamber 29 on the bottom side and the reservoir chamber 25 are at 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 the large-diameter portion 64a of the pump tube 64, and the pump chamber 68 is communicated with the cylinder upper and lower chambers 26 and 27 via the liquid passage 81 and the annular passage 79, thereby pumping. 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 overlaps the small diameter portion 64b of the pump tube 64. Closed. In this state, when the piston rod 48 expands and contracts due to the vibration of the suspension device during traveling, the pressure in the pump chamber 68 decreases due to the pump rod 31 in the small diameter portion 64b of the pump tube 64 retreating during the extension stroke. The check valve 71 is opened and the oil in the lower oil chamber 18 is introduced into the pump chamber 68 through the oil passage 69. In the contraction stroke, the pump rod 31 is advanced to pressurize the pump chamber 68, The check valve 70 is opened, and the oil in the pump chamber 68 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, and the cylinder upper / lower chamber 44. 45 and the reservoir chamber 25 are pressurized to extend the piston rod 48. In this way, the vehicle height is raised by repeating the pumping operation using the vibration during traveling. When the vehicle height reaches the standard vehicle height and the extension length of the piston rod is within the standard range, the notch 80 of the pump rod 31 overlaps the large diameter portion 64a of the pump tube 64, and the pump chamber 68 is placed on the cylinder. The pumping operation is released by communicating with the lower chambers 44 and 45.

  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 and the orifice passage 82 of the pump rod 31 are connected to 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 via the annular passage 79 and the orifice passage 82. The pressure oil in the cylinder upper and lower chambers 44 and 45 is returned to the oil chamber 18 and the cylinder upper and lower chambers 44 and 45 and the reservoir chamber 25 are depressurized. Vehicle height decreases. When the vehicle height decreases to the standard vehicle height and the extension length of the piston rod 48 falls within the standard range, the orifice passage 82 of the pump rod 31 is closed to overlap the small diameter portion 64b of the pump tube 64, and the cylinder upper / lower chamber 44 is closed. , 45 stops the return operation of the pressure oil.

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

  By the way, when the piston rod 48 is contracted and pumped, the hydraulic pressure in the upper and lower chambers 44 and 45 increases, and the oil liquid tends to leak from the sealing device 49. However, in this embodiment, since the rod seals are provided in two stages, even if oil leakage occurs from the first seal member 59 that places importance on sliding characteristics, the second seal made of a rubber oil seal is used. Leakage to the outside is prevented by the member 60. When the pressure of the leaked oil increases, 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, and therefore the oil liquid to the outside. Spillage is completely prevented. In addition, in this embodiment, since the pressure reducing valve 39 is provided in the partition member 22, when the pressure in the cylinder upper / lower chambers 44 and 45 is extremely increased, the pressure reducing valve 39 is opened and the oil liquid in the cylinder 26 is opened. Flows out into the lower oil chamber 28, so that safety is ensured.

  In the above-described embodiment, the case 21 is provided with the reservoir chamber 25, the cylinder 26, and the oil chamber 28 as an oil tank. However, the present invention is not limited to this. Alternatively, the oil chamber and the through hole 22a of the partition member 21 may be connected by piping.

It is sectional drawing which shows the principal part structure of the hydraulic shock absorber which concerns on this invention. It is a top view which shows an example of the shape of the disk which comprises the connection means of this invention. It is a front view which shows the assembly | attachment method and assembly state of the disc with respect to a pump rod. It is sectional drawing which shows the whole structure of this hydraulic shock absorber. It is sectional drawing which shows the piston part of this hydraulic shock absorber, and the structure around it. It is sectional drawing which shows the seal structure of this hydraulic shock absorber. It is sectional drawing which shows the non-return valve of a pump tube, and the structure around it. It is sectional drawing which shows the non-return valve of a pump rod, and the structure around it. It is sectional drawing which shows the operating state of the principal part of this hydraulic shock absorber. It is sectional drawing which shows the connection structure of the pump rod and partition member of the 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 rod 32 Connecting means 33 Base valve body (base valve body)
34 Oil passage 35 Fitting gap 36 Check valve (valve)
43 piston 48 piston rod 49 sealing device (sealing means)
52 Disc valve (Damping force generation mechanism)
53 Orifice passage (damping force generation mechanism)
55 Rod guide (guide member)
64 Pump tube (self-pumping mechanism)
68 Pump room (self-pumping mechanism)
70 Check valve for pump tube (self-pumping mechanism)
71 Pump rod check valve (self-pumping mechanism)
90 Circumferential groove of pump rod 91 Disc 92 Retainer 97 O-ring (seal member)
F passage

Claims (2)

A cylinder filled with oil, a case provided on the outer periphery of the cylinder to form a reservoir chamber between the cylinder, and a slidably fitted into the cylinder so that the inside of the cylinder is divided into two chambers. A piston that has one end connected to the piston and a hollow piston rod that extends to the outside through a guide member that closes the other end of the case and the cylinder, and the cylinder and the reservoir A base valve body having an oil passage communicating with the chamber; a valve provided in the base valve body for controlling the flow of oil in the oil passage; an oil tank comprising an oil chamber and a gas chamber; a partition member reservoir chamber within the case and one end of the base valve body is isolated from the said oil tank, engage and the O in the partition member one end through the base valve body While connecting the oil chamber of Rutanku, is tiltably connected to the partition member, the pump rod to permit a hollow pump rod the other end is inserted into the piston rod, the inclination of the pump rod And a gap formed between the base valve body, a seal member provided between the partition member and the pump rod for sealing between the cylinder and the oil tank, and the piston rod And a self-pumping mechanism that operates according to the expansion and contraction movement of the oil and raises the oil in the oil tank into the cylinder through the pump rod. A gap is provided in the pump rod penetrating portion of the base valve body, and a passage communicating with the reservoir chamber is formed between the base valve body and the partition member, and the cylinder and the cylinder are interposed via the passage and the gap. 2. The hydraulic shock absorber according to claim 1, wherein the reservoir chamber is communicated with the hydraulic shock absorber.

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