JP2009085262A - Hydraulic shock absorber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the risk of oil leakage in a hydraulic shock absorber, improve setting and responsiveness of a damping force generator, and improve assemblability.
In a hydraulic shock absorber 10, a second chamber 38B in a cylinder 11 is closed, and a separator 50 having a fitting hole 51 into which an insertion end of a piston rod 12 into the cylinder 11 is fitted is provided. The volume compensation chamber 60 for the insertion end to be fitted into the separator 50 of the piston rod 12 is provided on the side opposite to the second chamber 38B.
[Selection] Figure 1

Description

  The present invention relates to a hydraulic shock absorber.

  As a motorcycle rear damper, etc., a piston rod is liquid-tightly inserted into the cylinder via a rod guide provided at one end of the cylinder, a piston is provided at the insertion end of the piston rod into the cylinder, and the rod guide is located in the cylinder rather than the piston. A first chamber (rod side chamber) on the side and a second chamber (piston side chamber) on the side opposite to the rod guide are partitioned, and a damping force is generated by controlling the flow of the oil liquid between the first chamber and the second chamber. There is a single rod type hydraulic shock absorber in which a damping force generating device is provided on a piston. In this single rod type hydraulic shock absorber, in order to compensate the hydraulic oil for the volume of the piston rod entering / exiting the cylinder, a volume compensation chamber (oil reservoir chamber) defined by a second chamber in the cylinder and a separator is used. The second chamber and the oil reservoir chamber of the volume compensation chamber are communicated with each other through a throttle hole provided in the separator.

As another rear damper or the like of a motorcycle, as described in Patent Document 1, the piston rod is liquid-tightly inserted into the cylinder via two rod guides provided at both ends of the cylinder, and the piston rod is inserted into the cylinder. A damping force generator that provides a piston, divides a first chamber and a second chamber on both sides of the piston in the cylinder, and generates a damping force by controlling the flow of the oil liquid between the first chamber and the second chamber. There is a double rod type hydraulic shock absorber provided with a piston. This double rod type hydraulic shock absorber does not require a volume compensation chamber in the single rod type hydraulic shock absorber.
Reality 5-19621

  (1) Single rod type hydraulic shock absorbers are those in which the piston rod is liquid-tightly inserted only into the rod guide provided at one end of the cylinder, and the piston rod is sealed only at one point, so there is a risk of oil leakage. Although it has a low merit, it has the following problems.

  Due to the flow resistance R1 caused by the bending rigidity of the compression side damping valve of the damping force generating device provided in the piston, the diameter of the throttle hole provided in the separator for constituting the volume compensation chamber, and the sealed pressure in the pressurized gas chamber There is difficulty in mutual setting of the flow path resistance R2. That is, when R1 is larger than R2, a larger amount of oil than the volume of the piston rod entering the cylinder in the compression side stroke enters (discharges) the oil reservoir chamber of the volume compensation chamber, and the oil transferred from the second chamber to the first chamber is discharged. As a result of the shortage, the generation of the compression side damping force by the compression side damping valve becomes insufficient, and the responsiveness at the time of extension side reversal becomes worse. If R2 is set to be large, the return (replenishment) of oil from the oil reservoir chamber of the volume compensation chamber to the second chamber becomes worse at the time of reversing the extension side.

  (2) Since the double rod type hydraulic shock absorber does not include a volume compensation chamber, there is no inconvenience in setting and responsiveness of the above-described damping force generating device in the single rod type hydraulic shock absorber, but there are the following problems.

  The piston rod is inserted in a liquid-tight manner into two rod guides provided at both ends of the cylinder, and two seals are required for the piston rod, which increases the risk of oil leakage.

  Since there is no discharge of oil corresponding to the volume of the piston rod entering the cylinder in the compression side stroke, it is not possible to add a compression side damping force generator using this discharged oil liquid.

  When the cylinder is filled with oil, the cylinder is completely closed by the rod guides at both ends, so there is no escape for oil in the cylinder. Push the rod guide into the cylinder filled with oil and stop it with a retaining ring. Assembling is not good.

  An object of the present invention is to reduce the risk of oil leakage in a hydraulic shock absorber, improve the setting and responsiveness of a damping force generator, and improve assembly.

  Another object of the present invention is to add a compression side damping force generator in addition to the damping force generator provided on the piston.

  According to the first aspect of the present invention, a piston rod is liquid-tightly inserted into a cylinder containing oil liquid through a rod guide, and a piston is provided at a portion where the piston rod is inserted into the cylinder. The first chamber and the second chamber on the side opposite to the rod guide are partitioned, and a damping force generating device that generates a damping force by controlling the flow of the oil liquid between the first chamber and the second chamber is provided. In the hydraulic shock absorber, a second chamber in the cylinder is closed, and a separator having a fitting hole into which the insertion end of the piston rod into the cylinder is fitted is provided. On the opposite side of the second chamber across the separator, A volume compensation chamber for a fitting end to be fitted into the separator is provided, and the volume compensation chamber is constituted by an oil reservoir chamber into which the fitting end of the piston rod enters and a gas chamber.

  According to a second aspect of the present invention, in the first aspect of the present invention, the volume compensation chamber is composed of an oil reservoir chamber and a gas chamber partitioned by a movable partition wall member.

  According to a third aspect of the present invention, in addition to the first or second aspect of the present invention, the insertion end of the piston rod is inserted into the insertion hole of the separator from the middle of the compression side stroke.

  According to a fourth aspect of the present invention, in any one of the first to third aspects of the present invention, the first oil reservoir chamber on the side where the piston rod insertion end enters the oil reservoir chamber of the volume compensation chamber and the movable partition wall member side. The second oil reservoir chamber is divided into two, and a compression-side damping force generator is interposed between the first oil reservoir chamber and the second oil reservoir chamber.

  According to a fifth aspect of the present invention, in the first aspect of the present invention, the first chamber and the second chamber are communicated with each other, bypassing the damping force generating device provided in the piston, and also communicated with the oil reservoir chamber. A connecting passage is provided in the piston rod, a throttle passage is provided between the first chamber side and the second chamber side of the connecting passage, and the first and second chamber sides of the connecting passage and the oil reservoir chamber side In the meantime, a check valve that is opened by the pressure of the oil reservoir is provided.

(Claims 1 and 2)
(a) The piston rod is liquid-tightly inserted into a rod guide provided at one end of the cylinder, and is put in and out of a separator provided at the other end of the cylinder, and the volume of oil in the cylinder changes as the piston rod moves. Never do. The insertion hole provided in the separator is used to enter and exit the piston rod through a minute clearance, and does not cause the fluid to flow under the normal moving speed of the piston. Therefore, since the insertion hole of the separator does not form the throttle hole of the separator in the conventional single rod type hydraulic shock absorber, the flow resistance caused by the bending rigidity of the damping valve in the damping force generator provided in the piston The setting of the damping force generator and the responsiveness can be improved without any difficulty in the setting.

  (b) The piston rod is inserted in a liquid-tight manner only in the rod guide provided at one end of the cylinder, and the piston rod is sealed only at one location, so the risk of oil leakage is low.

  (c) When the cylinder is filled with oil, the cylinder is completely closed by the rod guide at one end, but if the piston is at a very slow speed, the oil in the cylinder will be inserted into the separator insertion hole and the piston rod. It is possible to escape to the volume compensation chamber through a minute clearance with the end. Therefore, the rod guide can be pushed into the cylinder filled with oil and stopped by the retaining ring, and the assemblability is good. The minute clearance between the insertion hole of the separator and the insertion end of the piston rod does not allow oil to flow under the normal moving speed of the piston.

(Claim 3)
(d) Since the insertion end of the piston rod is inserted into the insertion hole of the separator in the middle of the compression side stroke, the initial response of the compression side stroke by the damping force generator provided on the piston is deteriorated, in other words, the compression side stroke. The initial compression-side damping force can be reduced, and a position-dependent damping force generator can be easily configured.

(Claim 4)
(e) The first oil reservoir chamber on the side where the piston rod insertion end enters the oil reservoir chamber of the volume compensation chamber for the insertion end inserted into the separator of the piston rod, and the second oil reservoir chamber on the movable partition member side. The pressure side damping force generator is interposed between the first oil reservoir and the second oil reservoir. That is, the compression-side damping force generating device is provided in a path in which oil liquid corresponding to the volume of the piston rod that fits into the separator and enters the first oil reservoir in the compression stroke is discharged from the first oil reservoir to the second oil reservoir. The compression side damping force can be generated by the compression side damping force generator.

(Claim 5)
(f) Bypassing the damping force generator provided in the piston, the first chamber and the second chamber are communicated, and a communication path communicating with the oil reservoir is provided in the piston rod, A throttle passage was provided between the second chamber side, and a check valve opened by the pressure of the oil reservoir chamber was provided between the first chamber and second chamber sides of the communication path and the oil reservoir chamber side. When the stroke of the piston and the moving speed of the piston are large in the compression side stroke, if the pressure in the oil reservoir increases, the pressure in the oil reservoir opens the check valve and the first and second chambers (the first chamber is throttled) The pressure in the second chamber is increased (through the passage) (there is no fluid flow), and the oil in the second chamber is quickly compressed, and the damping force instantly rises at the compression side damping valve. In the extension stroke, the check valve is closed and the pressure does not escape to the oil sump chamber where the pressure becomes low.

  Therefore, the pressure in the gas chamber is lowered, the pressure-side flow resistance of the pressure-side damping force generator is lowered, and the damping force when the piston moving stroke is small is lowered to improve the riding comfort. When the moving stroke amount and the moving speed are large, accentuation can be performed through a damping characteristic with a striking effect with a quick rise of the compression side damping force, and the operability can be improved.

  1 is an overall sectional view showing a hydraulic shock absorber according to a first embodiment, FIG. 2 is a lower sectional view of FIG. 1, FIG. 3 is an upper sectional view of FIG. 1, FIG. 4 is an enlarged sectional view of an essential part of FIG. Is an overall sectional view showing a hydraulic shock absorber of Example 2, FIG. 6 is a lower sectional view of FIG. 5, FIG. 7 is an upper sectional view of FIG. 5, FIG. 8 is an enlarged sectional view of the main part of FIG. It is sectional drawing which shows a stop valve.

Example 1 (FIGS. 1 to 4)
As shown in FIGS. 1 to 4, the hydraulic shock absorber 10 has a hollow piston rod 12 inserted in a liquid-tight manner into a cylinder 11 containing oil and a suspension spring 13 is interposed between the cylinder 11 and the piston rod 12. is doing. The cylinder 11 includes a vehicle body side mounting portion 14, and the piston rod 12 includes an axle side mounting member 15 together with a lock nut 15 </ b> A. The piston rod 12 includes a base portion 12A that extends in and out of the cylinder 11 and is provided with an axle side attachment member 15, and an extension portion 12B that is screwed to the base portion 12A inside the cylinder 11 to make a coaxial.

  The hydraulic shock absorber 10 is provided with a spring load adjusting device 16 on the outer peripheral portion of the cylinder 11, and the spring load adjusting device 16 includes a spring receiver 17. The piston rod 12 is provided with a spring receiver 18 that is backed up and supported by the axle-side mounting member 15. A suspension spring 13 is interposed between the seat of the spring receiver 17 and the seat of the spring receiver 18.

  The hydraulic shock absorber 10 includes a rod guide 21 through which a piston rod 12 penetrates liquid-tightly at one end of a cylinder 11. The rod guide 21 is inserted in a liquid-tight manner into the cylinder 11 via an O-ring 22, and the piston rod 12 is slidable in a liquid-tight manner in an inner diameter portion including an oil seal 23, a bush 24, and a dust seal 25. The cylinder 11 is provided with a pressure side bumper 26 on the outside of the rod guide 21, and a bumper stopper 27 provided on the piston rod 12 abuts against the pressure side bumper 26 at the time of maximum compression to restrict the maximum compression stroke. Further, the cylinder 11 includes a washer 28 </ b> A and an extension side bump rubber 28 inside the rod guide 21.

  The hydraulic shock absorber 10 has a piston valve device (pressure side and extension side damping force generation device) 30. The hydraulic shock absorber 10 suppresses expansion and contraction vibrations of the cylinder 11 and the piston rod 12 due to the absorption of the impact force by the suspension spring 13 by the damping force generated by the piston valve device 30.

  In the piston valve device 30, a valve stopper 31, a pressure side damping valve 32, a piston 33, an extension side damping valve 34, and a valve stopper 35 are attached to the base 12A of the piston rod 12 inserted into the cylinder 11, and these are extended by an extension 12B. It is fixed.

  The piston 33 is in fluid-tight sliding contact with the inside of the cylinder 11 and divides the inside of the cylinder 11 into a first chamber 38A closer to the rod guide 21 than the piston 33 and a second chamber 38B closer to the anti-rod guide 21. The piston 33 includes a compression side damping valve 32 and a pressure side flow path 32A (not shown) that allows the first chamber 38A and the second chamber 38B to communicate with each other, and an extension side damping valve 34, and includes the first chamber 38A and the first chamber 38A. An extension-side flow path 34A that enables communication between the two chambers 38B is provided.

  The piston valve device 30 has an extension side damping force adjustment device 40. The extension-side damping force adjusting device 40 bypasses the piston valve device 30 (the compression-side damping valve 32 and the extension-side damping valve 34 provided on the piston 33) and establishes a communication path 41 that communicates the first chamber 38A and the second chamber 38B. It is provided on the piston rod 12. The extension side damping force adjusting device 40 is provided with a valve seat 42 on the opening end side of the communication path 41 to the second chamber 38B, and an adjustment rod 43 provided with a needle valve 43A facing the valve seat 42 at the tip of the piston rod 12. It is liquid-tightly inserted into the hollow part so that it can advance and retract in the axial direction. The extension side damping force adjusting device 40 pivotally supports the adjuster 44 on the axle side mounting member 15 so that the adjuster 44 can be screwed, and abuts the base end portion of the adjustment rod 43 on the tapered cam surface 44A of the adjuster 44. The adjusting rod 44 is screwed to advance and retract the adjusting rod 43 in the axial direction, the needle valve 43A of the adjusting rod 43 adjusts the opening area (throttle passage) of the valve seat 42 of the communication path 41, and the expansion side damping force can be adjusted. To.

  The hydraulic shock absorber 10 closes the second chamber 38B in the cylinder 11 and extends the insertion end of the piston rod 12 into the cylinder 11, that is, an extension portion 12B (cylinder) screwed to the base portion 12A of the piston rod 12 in this embodiment. 11, the outer diameter of the base 12 </ b> A facing the first chamber 38 </ b> A in the cylinder 11 and the outer diameter of the extension 12 </ b> B facing the second chamber 38 </ b> B have the same diameter). 11 is held by a ridge provided on the inner diameter of 11. At this time, the separator 50 is fixed by a retaining ring 55 by loading a bush case 53 having a bush 52 forming the insertion hole 51 into the hole of the housing 50 </ b> A via the O-ring 54. The insertion hole 51 of the separator 50 forms a sufficiently small minute clearance with the extension portion 12B of the piston rod 12, and this minute clearance is connected to the volume compensation chamber 60 described later for the temperature expansion / contraction of the oil in the cylinder 11. Although this is circulated between to compensate for this, the oil liquid is not allowed to circulate under the normal moving speed of the piston 33.

  The hydraulic shock absorber 10 has a volume compensation chamber 60 for a fitting end fitted into the separator 50 of the extension 12B of the piston rod 12 on the opposite side of the second chamber 38B across the separator 50 on the other end side of the cylinder 11. Is provided. The volume compensation chamber 60 includes an oil reservoir chamber 61 into which the insertion end of the extension portion 12 </ b> B of the piston rod 12 enters, and a pressurized gas chamber 62 partitioned by the oil reservoir chamber 61 and the movable partition wall member 63. The movable partition member 63 of the present embodiment includes a free piston 63A, and the free piston 63A is in fluid-tight sliding contact with the inner periphery of the other end side of the cylinder 11 via an O-ring 63B. However, the movable partition member 63 is not necessarily provided.

  In the hydraulic shock absorber 10, when the piston rod 12 extends and contracts, the base portion 12 </ b> A on one end side of the piston rod 12 enters and exits the first chamber 38 </ b> A in the cylinder 11 through the rod guide 21 provided at one end of the cylinder 11. The extension portion 12B on the other end side of the cylinder 11 enters and exits the second chamber 38B of the cylinder 11 in the separator 50 provided on the other end side of the cylinder 11. Since the base portion 12 </ b> A and the extension portion 12 </ b> B have the same diameter, the volume of oil in the cylinder 11 is not changed by the movement of the piston rod 12. At this time, the fitting end fitted into the separator 50 of the extension portion 12B of the piston rod 12 enters the oil reservoir chamber 61 of the volume compensation chamber 60, and the oil corresponding to the entering volume displaces the movable partition member 63.

Therefore, the hydraulic shock absorber 10 performs a damping action as follows.
(When compressed)
The oil in the second chamber 38B flows to the first chamber 38A through the pressure side flow path 32A, and this oil deflects and deforms the pressure side valve 32 to obtain a compression side damping force.

(When stretched)
When the relative speed between the cylinder 11 and the piston rod 12 is low, the oil in the first chamber 38A passes through the connecting passage 41 of the piston rod 12 whose opening degree is adjusted by the needle valve 43A of the adjustment rod 43 and enters the second chamber 38B. The expansion side damping force is obtained by the flow resistance and the throttle resistance by the needle valve 43A during this time. Further, when the relative speed between the cylinder 11 and the piston rod 12 is medium to high, the oil in the first chamber 38A passes through the expansion side flow path 34A, bends and deforms the expansion side valve 34, flows to the second chamber 38B, and extends. Get the damping force.
The expansion and contraction vibration of the hydraulic shock absorber 10 is suppressed by the damping force on the compression side and the extension side.

According to the present embodiment, the following operational effects can be obtained.
(a) The piston rod 12 is inserted in a liquid-tight manner into a rod guide 21 provided at one end of the cylinder 11 and is put in and out of a separator 50 provided at the other end of the cylinder 11 so that the volume of oil in the cylinder 11 is reduced. It does not change with the movement of the piston rod 12. The insertion hole 51 provided in the separator 50 allows the piston rod 12 to enter and exit through a minute clearance, and does not cause the fluid to flow under the normal moving speed of the piston 33. Therefore, since the insertion hole 51 of the separator 50 does not constitute a separator throttle hole in a conventional single rod type hydraulic shock absorber, the bending rigidity of the compression side damping valve 32 in the damping force generating device 30 provided in the piston 33 is achieved. Therefore, the setting and response of the damping force generator 30 can be improved without causing any difficulty in setting the flow resistance due to the above.

  (b) Since the piston rod 12 is inserted in a liquid-tight manner only in the rod guide 21 provided at one end of the cylinder 11 and the piston rod 12 is sealed only at one place, the risk of oil leakage is low.

  (c) When the cylinder 11 is filled with oil, the cylinder 11 is completely closed by the rod guide 21 at one end. However, when the piston 33 is extremely slow, the oil in the cylinder 11 is inserted into the separator 50. It is possible to escape to the volume compensation chamber 60 through a minute clearance between the hole 51 and the insertion end of the piston rod 12. Therefore, the rod guide 21 can be pushed into the cylinder 11 filled with oil and stopped by the retaining ring 21A, and the assemblability is good. The minute clearance between the insertion hole 51 of the separator 50 and the insertion end of the piston rod 12 does not allow oil to flow under the normal moving speed of the piston 33.

  In the hydraulic shock absorber 10, the extension portion 12 </ b> B of the piston rod 12 has a length that fits into the insertion hole 51 of the separator 50 even at the extended end. However, the extension 12B of the piston rod 12 is shortened as shown by two-dotted hatching in FIG. It can also be configured to. Thereby, the responsiveness at the initial stage of the compression side stroke by the damping force generation device 30 is deteriorated. In other words, the compression side damping force at the initial stage of the compression side stroke can be lowered, and the position-dependent damping force generation device 30 can be easily configured.

Example 2 (FIGS. 5 to 9)
As shown in FIGS. 5 to 8, the hydraulic shock absorber 110 has a hollow piston rod 112 inserted in a liquid-tight manner into a cylinder 111 containing oil and a suspension spring 113 is interposed between the cylinder 111 and the piston rod 112. is doing. The cylinder 111 includes a vehicle body side mounting portion 114, and the piston rod 112 includes an axle side mounting member 115 together with a lock nut 115A. The piston rod 112 includes a base portion 112A that extends in and out of the cylinder 111 and is provided with an axle-side mounting member 115, and an extension portion 112B that is screwed into the base portion 112A inside the cylinder 111 and is coaxial.

  The hydraulic shock absorber 110 is provided with a spring load adjusting device 116 on the outer peripheral portion of the cylinder 111, and the spring load adjusting device 116 includes a spring receiver 117. The piston rod 112 is provided with a spring receiver 118 that is backed up and supported by the axle-side mounting member 115. A suspension spring 113 is interposed between the seat of the spring receiver 117 and the seat of the spring receiver 118. A spring guide 119 is supported on the spring receiver 118.

  The hydraulic shock absorber 110 includes a rod guide 121 through which a piston rod 112 penetrates in a liquid-tight manner at one end of a cylinder 111. The rod guide 121 is inserted in a liquid-tight manner into the cylinder 111 through an O-ring 122, and the piston rod 112 is slidable in a liquid-tight manner in an inner diameter portion including an oil seal 123, a bush 124, and a dust seal 125. The cylinder 111 includes a pressure side bumper 126 outside the rod guide 121, and a bumper stopper 127 provided in the piston rod 112 abuts against the pressure side bumper 126 and restricts the maximum compression stroke at the time of maximum compression. Further, the cylinder 111 includes a washer 128 </ b> A and an extension side bump rubber 128 inside the rod guide 121.

  The hydraulic shock absorber 110 has a piston valve device (pressure side and extension side damping force generating device) 130. The hydraulic shock absorber 110 suppresses expansion and contraction vibration of the cylinder 111 and the piston rod 112 due to the absorption of the impact force by the suspension spring 113 by the damping force generated by the piston valve device 130.

  In the piston valve device 130, a valve stopper 131, a pressure side damping valve 132, a piston 133, an extension side damping valve 134, and a valve stopper 135 are attached to a base 112A of a piston rod 112 inserted into a cylinder 111, and these are extended by an extension 112B. It is fixed.

  The piston 133 is in fluid-tight sliding contact with the inside of the cylinder 111, and divides the inside of the cylinder 111 into a first chamber 138A on the rod guide 121 side and a second chamber 138B on the anti-rod guide 121 side with respect to the piston 133. The piston 133 includes a pressure-side damping valve 132 to allow communication between the first chamber 138A and the second chamber 138B, and an extension-side damping valve 134 to include the first chamber 138A and the second chamber 138B. And an extension-side flow path 134A (not shown) that can communicate with each other.

  The piston valve device 130 includes an extension side damping force generation device 140. The extension-side damping force generator 140 bypasses the piston valve device 130 (the compression-side damping valve 132 and the extension-side damping valve 134 provided on the piston 133) and establishes a communication path 141 that communicates the first chamber 138A and the second chamber 138B. It is provided on the piston rod 112. The extension side damping force generating device 140 is provided with a valve seat 142 on the opening end side of the communication path 141 to the second chamber 138B, and an adjustment rod 143 provided with a needle valve 143A facing the valve seat 142 at the tip of the piston rod 112. It is liquid-tightly inserted into the hollow part so that it can advance and retract in the axial direction. The extension-side damping force generator 140 pivotally supports the adjuster 144 on the axle-side mounting member 115 so that the adjuster 144 can be screwed, and abuts the base end portion of the adjust rod 143 on a tapered cam surface (not shown) of the adjuster 144. Adjustment rod 144 can be screwed to advance / retract adjustment rod 143 in the axial direction, and needle valve 143A of adjustment rod 143 can adjust the opening area (throttle passage) of valve seat 142 of connecting passage 141 to adjust the extension side damping force. To.

  The hydraulic shock absorber 110 closes the second chamber 138B in the cylinder 111 and extends to the insertion end of the piston rod 112 into the cylinder 111, in this embodiment, the extension 112B (cylinder) screwed to the base 112A of the piston rod 112. 111, the outer diameter of the base portion 112A facing the first chamber 138A and the outer diameter of the extension portion 112B facing the second chamber 138B have the same diameter). Retained. At this time, the separator 150 is fixed by a nut 155 that is loaded into the inner diameter of the cylinder 111 via the O-ring 154 with a bush case 153 having a bush 152 that forms the insertion hole 151 and screwed into the inner diameter of the cylinder 111. The The insertion hole 151 of the separator 150 forms a sufficiently small minute clearance with the extension part 112B of the piston rod 112, and this minute clearance allows the temperature expansion / contraction of the oil liquid in the cylinder 111 to be compared with the volume compensation chamber 160 described later. Although this is made to circulate between and compensate for this, the circulation of the oil liquid under the normal moving speed of the piston 133 is not allowed.

  The hydraulic shock absorber 110 has a volume compensation chamber 160 for a fitting end fitted into the separator 150 of the extension 112B of the piston rod 112 on the opposite side of the second chamber 138B across the separator 150 on the other end side of the cylinder 111. Is provided. The volume compensation chamber 160 includes an oil reservoir chamber 161 into which the insertion end of the extension 112B of the piston rod 112 enters, and a pressurized gas chamber 162 partitioned by the oil reservoir chamber 161 and the movable partition member 163. However, the movable partition member 163 is not necessarily provided.

  The hydraulic shock absorber 110 includes an oil reservoir chamber 161 of the volume compensation chamber 160, a first oil reservoir chamber 161 </ b> A on the side where the insertion end of the extension 112 </ b> B of the piston rod 112 enters, and a second oil on the movable partition wall member 163 side. The reservoir chamber 161B is divided into two, and a compression-side damping force generator 170 is interposed between the first oil reservoir chamber 161A and the second oil reservoir chamber 161B. In the present embodiment, a first oil reservoir chamber 161 </ b> A is provided in the cylinder 111, and a second oil reservoir chamber 161 </ b> B and a pressurized gas chamber 162 are provided in a sub tank 171 attached to the cylinder 111. As the compression side damping force generator 170, for example, the one described in JP-A-3-292429 can be adopted. In the hydraulic shock absorber 110, when the extension 112B of the piston rod 112 is fitted into the separator 150 and enters the first oil reservoir 161A in the compression side stroke, the oil corresponding to the entry volume of the extension 112B is the first. The compression side damping force generator 170 is provided in the path discharged from the oil reservoir chamber 161A to the second oil reservoir chamber 161B, and the compression side damping force generator 170 generates a compression side damping force. The compression-side damping force generator 170 includes a compression-side damping force adjustment device 180 operated by an adjuster 181 and can adjust the above-described compression-side damping force generated by the compression-side damping force generation device 170.

  The hydraulic shock absorber 110 is provided with the communication path 141 that bypasses the piston valve device 130 and communicates the first chamber 138A and the second chamber 138B as described above, and the first chamber 138A side and the second chamber of the communication path 141 are provided. The above-mentioned throttle passage formed by the needle valve 143A and the valve seat 142 is provided between the side of 138B, and this connecting passage 141 is extended at the piston rod 112 (hollow portion of the extension portion 112B) to form the oil reservoir chamber 161. It communicates with (first oil reservoir 161A). The pressure in the oil reservoir chamber 161 (oil reservoir chamber 161A) is between the first chamber 138A and second chamber 138B side of the communication path 141 and the oil reservoir chamber 161 (first oil reservoir chamber 161A) side. A check valve 190 is provided. As shown in FIG. 9, the check valve 190 can seal the hollow valve case 191 that is press-fitted into the hollow portion of the extension 112 </ b> B, the hollow valve seat 192 that is fitted to the valve case 191, and the valve seat 192. Valve body 193, a spring 194 that biases the valve body 193 toward the valve seat 192, and an inner member that is inserted into the valve case 191 so as to accommodate the spring 194 and restrict the open end of the valve seat 193 Case 195 is formed. Thus, in the hydraulic shock absorber 110, during compression, the valve body 193 is opened by the pressure of the oil reservoir chamber 161, and the pressure of the oil reservoir chamber 161 passes through the communication path 141, the passage of the valve case 191 and the passage of the valve seat 192. , Extending to the first chamber 138A and the second chamber 138B. At the time of extension, the valve body 193 is closed, and the oil in the first chamber 138A is transferred to the second chamber 138B through the communication path 141 and the passage of the valve case 191.

  In the hydraulic shock absorber 110, when the piston rod 112 extends and contracts, a base portion 112 </ b> A on one end side of the piston rod 112 enters and exits the first chamber 138 </ b> A in the cylinder 111 through a rod guide 121 provided at one end of the cylinder 111. The extension portion 112B on the other end side of the cylinder 111 enters and exits the second chamber 138B in the cylinder 111 at the separator 150 provided on the other end side of the cylinder 111. Since the base 112 </ b> A and the extension 112 </ b> B have the same diameter, the volume of oil in the cylinder 111 is not changed by the movement of the piston rod 112. At this time, the fitting end of the extension portion 112B of the piston rod 112 fitted into the separator 150 enters the first oil reservoir chamber 161A of the volume compensation chamber 160, and the oil corresponding to the entry volume passes through the compression side damping force generator 170. The movable partition member 163 is displaced by being transferred to the second oil reservoir 161B.

Accordingly, the hydraulic shock absorber 110 performs a damping action as follows.
(When compressed)
The oil in the second chamber 138B flows to the first chamber 138A through the pressure side flow path 132A, and this oil deflects and deforms the pressure side damping valve 132 to obtain the pressure side damping force.

  At this time, the fitting end fitted into the separator 150 of the extension part 112B of the piston rod 112 enters the first oil reservoir 161A of the separator 160, and the oil corresponding to this entry volume passes through the compression-side damping force generator 170 to the second. During the transfer to the oil reservoir chamber 161 </ b> B, the compression side damping force generator 170 generates the compression side damping force set by the compression side damping force adjusting device 180.

(When stretched)
When the relative speed between the cylinder 111 and the piston rod 112 is low, the oil in the first chamber 138A passes through the communication path 141 of the piston rod 112 whose opening is adjusted by the needle valve 143A of the adjustment rod 143 and enters the second chamber 138B. The expansion side damping force is obtained by the flow and the throttle resistance by the needle valve 143A during this period. Further, when the relative speed between the cylinder 111 and the piston rod 112 is medium to high, the oil in the first chamber 138A passes through the expansion-side flow path 134A, and the expansion-side damping valve 134 is bent and deformed to flow into the second chamber 138B. Get side damping force.

According to the present embodiment, the following operational effects can be obtained.
(a) The piston rod 112 is liquid-tightly inserted into a rod guide 121 provided at one end of the cylinder 111, and is inserted into and exited from a separator 150 provided at the other end of the cylinder 111, so that the volume of oil in the cylinder 111 is reduced. It does not change with the movement of the piston rod 112. The fitting hole 151 provided in the separator 150 allows the piston rod 112 to enter and exit through a minute clearance, and does not cause the fluid to flow under the normal movement speed of the piston 133. Therefore, since the fitting hole 151 of the separator 150 does not constitute a separator throttle hole in a conventional single rod type hydraulic shock absorber, the bending rigidity of the compression side damping valve 132 in the damping force generating device 130 provided in the piston 133 is reduced. The setting and response of the damping force generator 130 can be improved without any difficulty in setting the flow resistance due to the above.

  (b) The piston rod 112 is inserted into the rod guide 121 provided at one end of the cylinder 111 in a liquid-tight manner, and the piston rod 112 is sealed only at one location, so that the risk of oil leakage is low.

  (c) When the cylinder 111 is filled with oil, the cylinder 111 is completely closed by the rod guide 121 at one end. However, when the piston 133 is at a very low speed, the oil in the cylinder 111 is inserted into the separator 150. It is possible to escape to the volume compensation chamber 160 side through a minute clearance between the hole 151 and the insertion end of the piston rod 112. Therefore, the rod guide 121 can be pushed into the cylinder 111 filled with oil and stopped by the retaining ring 121A, and the assemblability is good. The minute clearance between the insertion hole 151 of the separator 150 and the insertion end of the piston rod 112 does not allow oil to flow under the normal movement speed of the piston 133.

  (d) The oil reservoir chamber 161 of the volume compensation chamber 160 for the insertion end to be fitted into the separator 150 of the piston rod 112 is connected to the first oil reservoir 161A and the movable partition wall member 163 on the side where the insertion end of the piston rod 112 enters. The second oil reservoir chamber 161B is divided into two, and the compression side damping force generator 170 is interposed between the first oil reservoir chamber 161A and the second oil reservoir chamber 161B. That is, in the path through which oil corresponding to the volume of the piston rod 112 inserted into the separator 150 and entering the first oil reservoir 161A in the pressure side stroke is discharged from the first oil reservoir 161A to the second oil reservoir 161B. The compression side damping force generator 170 is provided, and the compression side damping force generator 170 can generate the compression side damping force.

  (e) Bypassing the damping force generator 130 provided in the piston 133, the first chamber 138A communicates with the second chamber 138B, and the communication path 141 communicating with the oil reservoir 161 is provided in the piston rod 112, and the communication path 141, a throttle passage (needle valve 143A) is provided between the first chamber 138A side and the second chamber 138B side, and the first chamber 138A and second chamber 138B side of the communication path 141 and the oil reservoir chamber 161 side. The check valve 190 that is opened by the pressure of the oil reservoir 161 is provided therebetween. When the moving stroke amount and moving speed of the piston 133 are large in the pressure side stroke, when the pressure of the oil reservoir chamber 161 is increased, the pressure of the oil reservoir chamber 161 opens the check valve 190 and the first chamber 138A and the second chamber 138B. The pressure in the first chamber 138A is increased (through the throttle passage) (there is no oil flow), the oil in the second chamber 138B is quickly compressed, and the damping force rises instantaneously in the compression side damping valve 132. In the extension stroke, the check valve 190 is closed, and the pressure does not escape to the oil reservoir chamber 161 where the pressure becomes low.

  Accordingly, the sealing pressure of the gas chamber 162 is lowered, the pressure side flow resistance of the compression side damping force generator 170 is lowered, and the damping force when the moving stroke amount of the piston is small is lowered to improve the riding comfort. When the moving stroke amount and moving speed of the piston are large, accentuation can be provided through a damping characteristic with a striking effect with a quick rise of the compression side damping force, and the operability can be improved.

  In the hydraulic shock absorber 110, the extension 112B of the piston rod 112 has a length that fits into the fitting hole 151 of the separator 150 at the extended end. However, the extension 112B of the piston rod 112 is shortened as shown by two-dotted hatching in FIG. It can also be configured to. Thereby, the responsiveness at the initial stage of the compression side stroke by the piston valve device 130 is deteriorated. In other words, the compression side damping force at the initial stage of the compression side stroke can be lowered, and the position-dependent damping force generator 130 can be easily configured.

  Although the embodiments of the present invention have been described in detail with reference to the drawings, the specific configuration of the present invention is not limited to these embodiments, and even if there is a design change or the like without departing from the gist of the present invention. It is included in the present invention.

1 is an overall cross-sectional view showing a hydraulic shock absorber according to a first embodiment. FIG. 2 is a lower cross-sectional view of FIG. FIG. 3 is a top sectional view of FIG. FIG. 4 is an enlarged cross-sectional view of the main part of FIG. FIG. 5 is an overall sectional view showing the hydraulic shock absorber according to the second embodiment. 6 is a lower cross-sectional view of FIG. FIG. 7 is a top sectional view of FIG. FIG. 8 is an enlarged cross-sectional view of the main part of FIG. FIG. 9 is a cross-sectional view showing a check valve.

Explanation of symbols

10, 110 Hydraulic shock absorber 11, 111 Cylinder 12, 112 Piston rod 21, 121 Rod guide 30, 130 Damping force generator 33, 133 Piston 38A, 138A First chamber 38B, 138B Second chamber 41, 141 Communication path 43A, 143A Needle valve (throttle passage)
50, 150 Separator 51, 151 Insertion hole 60, 160 Volume compensation chamber 61, 161 Oil reservoir chamber 62, 162 Gas chamber 63, 163 Movable partition member 161A First oil reservoir chamber 161B Second oil reservoir chamber 190 Check valve

Claims (5)

The piston rod is inserted into the cylinder containing the oil liquid in a fluid-tight manner via the rod guide, the piston is provided at the insertion portion of the piston rod into the cylinder, the first chamber on the rod guide side of the piston and the anti-rod in the cylinder In the hydraulic shock absorber having a damping force generating device that divides the second chamber on the guide side and generates a damping force by controlling the flow of the oil liquid between the first chamber and the second chamber,
The second chamber in the cylinder is closed, and a separator having a fitting hole into which the insertion end of the piston rod into the cylinder is fitted is provided.
On the opposite side of the second chamber across the separator, a volume compensation chamber for the insertion end that fits into the separator of the piston rod is provided,
The volume compensation chamber is composed of an oil reservoir chamber into which a fitting end of the piston rod enters and a gas chamber.   The hydraulic shock absorber according to claim 1, wherein the volume compensation chamber includes an oil reservoir chamber and a gas chamber partitioned by a movable partition wall member.   The hydraulic shock absorber according to claim 1 or 2, wherein the insertion end of the piston rod is fitted into the insertion hole of the separator in the middle of the compression stroke.   The oil reservoir chamber of the volume compensation chamber is divided into a first oil reservoir chamber on the side where the piston rod insertion end enters and a second oil reservoir chamber on the movable partition member side, and the first oil reservoir chamber and the second oil reservoir chamber. The hydraulic shock absorber according to any one of claims 1 to 3, wherein a compression side damping force generator is interposed between the reservoirs. Bypassing the damping force generator provided in the piston to communicate the first chamber and the second chamber, and providing a communication path to the oil reservoir chamber in the piston rod;
A throttle passage is provided between the first chamber side and the second chamber side of the communication path,
The hydraulic shock absorber according to any one of claims 1 to 4, wherein a check valve is provided between the first chamber and the second chamber side of the communication path and the oil reservoir chamber side, and the check valve is opened by the pressure of the oil reservoir chamber.

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