JP6338878B2 - Hydraulic shock absorber - Google Patents

Description

  The present invention relates to a hydraulic shock absorber, and more particularly, to a hydraulic shock absorber that has good response when a damping force is generated.

2. Description of the Related Art Conventionally, as disclosed in Patent Document 1, a two-wheeled hydraulic shock absorber includes a piston body attached to a piston rod inserted into a cylinder to form a buffer body, and a compression side oil chamber and an extension side oil sectioned by the piston. There is a hydraulic shock absorber configured such that hydraulic oil can flow between the chambers and the damping force generation site.
This damping force generator is configured to apply a damping force to hydraulic fluid that moves from the compression side oil chamber to the extension side oil chamber in the compression side stroke and from the extension side oil chamber to the compression side oil chamber in the extension side stroke. . That is, the damping force generating device causes the hydraulic fluid in the compression side oil chamber to flow toward the expansion side oil chamber in the compression side stroke and the hydraulic fluid in the expansion side oil chamber to flow toward the hydraulic oil chamber in the expansion side stroke. The pressure side damping valve is provided on the upstream side of the pressure side flow path, and the pressure side check valve is provided on the downstream side to generate the damping force of the pressure side stroke, and the extension side damping is provided on the upstream side of the extension side flow path. The extension side check valve is provided on the downstream side of the valve so as to generate a damping force in the extension side stroke. In this case, temperature compensation means is added to the damping force generator. This temperature compensation means is provided with an oil reservoir chamber whose pressure can be adjusted, and the volume of the oil reservoir chamber is reduced by the piston rod entering the cylinder by the damping operation of the damping force generator. Or the volume of the hydraulic oil expands due to the increase in the temperature of the hydraulic oil, so that the volume of the hydraulic oil increases. Therefore, it compensates for the piston rod entry volume and absorbs the thermal expansion of the hydraulic oil. It is provided for temperature compensation.

JP 2011-27255 A

  However, in the hydraulic shock absorber having the above configuration, the hydraulic oil flows unnecessarily into the oil reservoir chamber of the volume compensation means and the temperature compensation means even during the damping operation of the damping force generator, so that the damping operation is rarely in an insufficiently damped state. This causes a problem that the response of attenuation is deteriorated. That is, in the compression side stroke, the hydraulic oil does not sufficiently flow into the expansion side oil chamber and the flow rate becomes insufficient, and bubbles are generated and cavitation occurs, which adversely affects the next expansion side stroke and obtains a desired damping force. However, the responsiveness of the damping force may be deteriorated. This problem can occur not only in the compression side stroke but also in the extension side stroke.

  The present invention has been made in view of these problems, and an object of the present invention is to provide a hydraulic shock absorber that does not cause a deficiency of the dampening force when generating the dampening force and improves the response when the dampening force is generated.

As a configuration of the hydraulic shock absorber according to the present invention for solving the above-described problems, a vehicle body side tube, an axle side tube that is slidably fitted to the vehicle body side tube, and a bottom of the axle side tube are provided upright. A cylindrical cylinder tube formed in the cylinder tube and in close contact with the inner periphery of the axle side tube in a liquid-tight state, the vehicle body side of the inner space of the axle side tube is an air chamber, and the axle side is a hydraulic oil chamber A partition member that partitions the vehicle body side tube and the axle side tube so as to be movable together with the vehicle body side tube, and the inside of the cylinder tube extends toward the vehicle body side of the hydraulic oil chamber. A piston that divides the oil chamber and axle side into a pressure side oil chamber, and is attached to the piston and can move in and out of the cylinder tube along the axial direction of the cylinder tube A rod is provided, and the outer periphery of the rod is erected from the bottom of the axle-side tube so that the inner peripheral side communicates with the outside air, and extends from the piston toward the bottom of the axle-side tube in a liquid-tight state. A cylindrical guide tube, a space formed between an inner circumference of the axle side tube and an outer circumference of the cylinder tube, and a flow hole that allows mutual flow of the hydraulic oil in communication with the extension side oil chamber A fluid passage between oil chambers that allows the hydraulic oil to flow between the pressure side oil chamber and the extension side oil chamber, and an operation that is provided outside the fluid oil chamber and flows through the fluid passage between the oil chambers. A damping force generating device in which a compression side damping force generation unit and an extension side damping force generation unit that generate resistance by generating resistance in oil are provided in series along the flow direction; and the compression side damping force generation unit and the extension side Part of hydraulic oil flows in between the side damping force generation part And a temperature compensation means having a pressure adjusting oil reservoir that absorbs the temperature expansion generated in the hydraulic oil, in the pressure side stroke and the extension side stroke in the operation of the hydraulic buffer. Based on the pressure of the hydraulic oil flowing in the direction of the pressure adjusting oil reservoir chamber, the flow rate of the hydraulic oil flowing in the direction of the pressure adjusting oil reservoir chamber is changed to the hydraulic oil when the piston other than the pressure side stroke and the extension side stroke is not operating. Since the hydraulic oil flow rate control means for limiting the amount to a smaller amount than that at the time of outflow is further provided, the flow of the hydraulic oil into the pressure adjusting oil reservoir chamber is restricted by the hydraulic oil flow rate control means, so the pressure side oil chamber in the pressure side stroke Since there is no shortage of hydraulic oil flow rate from the flow path side to the extension side oil chamber flow direction or the flow direction of hydraulic oil in the opposite direction to the above-mentioned direction in the extension side stroke, the damping force is generated by the damping force generator. Damping force without causing power shortage Responsiveness at the time of occurrence can be improved.

  As another configuration of the hydraulic shock absorber according to the present invention, the hydraulic oil flow rate control means includes a return flow path that communicates between the damping force generator side and the pressure adjusting oil reservoir chamber, Since the flow switching device has a pressure suppression flow path having a smaller opening than the flow path and a check valve mechanism that opens the pressure suppression flow path and closes the return flow path, the pressure can be reduced with a simple configuration. The suppression channel and the return channel can be switched.

  As another configuration of the hydraulic shock absorber according to the present invention, the return flow path is opened by the outflow pressure of the hydraulic oil from the pressure adjusting oil reservoir chamber when the piston is not in operation, During operation, the hydraulic oil can flow smoothly from the pressure adjusting oil reservoir.

  Further, as another configuration of the hydraulic shock absorber according to the present invention, the pressure suppression flow path is closed when the return flow path is opened, so that the hydraulic oil can surely flow out from the return flow path.

  As another configuration of the hydraulic shock absorber according to the present invention, the damping force generator extends between the compression side damping force generation unit and the extension side damping force generation unit from the compression side oil chamber flow path side in the compression side stroke. A hydraulic fluid flowing in the direction of the side oil chamber, and an intermediate chamber through which the hydraulic oil flowing in the direction of the pressure side oil chamber from the side of the expansion side oil chamber passes in the extension side stroke; Since one end of the passage communicates with the intermediate chamber side, the hydraulic oil can be flowed into and out of the pressure adjusting oil reservoir chamber in both the compression side stroke and the extension side stroke.

  Further, as another configuration of the hydraulic shock absorber according to the present invention, the opening amount of the pressure suppression flow path opened and closed by the check valve mechanism is an amount corresponding to the expansion due to the temperature rise of the hydraulic oil in the damping force generator. Since the opening amount is set to allow the hydraulic oil to flow from the intermediate chamber side toward the pressure adjusting oil reservoir chamber, the hydraulic oil corresponding to the expansion when temperature expansion occurs in the hydraulic oil is pressure adjusted. Since it flows in the direction of the oil reservoir chamber, temperature compensation for the operation of the hydraulic shock absorber can be reliably obtained.

  As another configuration of the hydraulic shock absorber according to the present invention, a pressure adjusting oil reservoir chamber of the temperature compensation means is connected to an intermediate chamber via a hydraulic oil guide pipe, and the hydraulic oil passage of the guide pipe Since the check valve mechanism is provided inside, when temperature expansion occurs in the hydraulic oil with a simple configuration, temperature compensation can be reliably performed so that the internal pressure of the compression side oil chamber and the extension side oil chamber does not increase.

It is sectional drawing of a front fork. It is an enlarged view of a damping force generator. It is the enlarged view of a damping force adjustment part, and the elements on larger scale of the expansion side damping force adjustment part. It is a figure which shows a flow-path switching apparatus. It is a figure which shows operation | movement of a flow-path switching apparatus. It is a figure which shows the flow of the hydraulic oil in a damping force generator.

  FIG. 1 is a cross-sectional view showing an embodiment of a front fork constituting a hydraulic shock absorber main body according to the present invention. As shown in FIG. 1, the front fork 10 is an inverted front fork in which an outer tube 11 as a vehicle body side tube and an inner tube 12 as an axle side tube are arranged. The outer periphery of the inner tube 12 is slidably provided on the bearings 12A and 12B fitted to be spaced apart from each other. A suspension spring 14 is interposed above the front fork 10 and biased in a direction in which the outer tube 11 and the inner tube 12 are separated from each other.

  A cap 13 for sealing the front fork 10 is screwed to the upper end of the outer tube 11. The cap 13 is composed of a base nut 24 whose outer periphery is screwed in an airtight manner with the inner periphery of the outer tube 11, and an adjustment bolt 21 is interposed in a hole in the center side of the base nut 24 in an airtight state. The adjusting bolt 21 is rotatably attached to the base nut 24 by a fixing means (not shown) so that the adjusting bolt 21 does not move up and down with respect to the base nut 24 even if the adjusting bolt 21 is rotated. The adjustment bolt 21 includes a small-diameter shaft portion 21 </ b> A having a hollow portion 21 </ b> B extending toward the inner tube 12 at the lower portion. The inner periphery of a cylindrical lifting nut 23 that moves up and down along the axis of the adjusting bolt 21 by the rotation of the adjusting bolt 21 is screwed into the outer peripheral side of the tip of the small-diameter shaft portion 21A. The elevating nut 23 includes an upper spring receiving portion 25 formed of a flange on which the suspension spring 14 is seated on the outer periphery.

  By moving the elevating nut 23 up and down by rotating the adjusting bolt 21, the upper spring receiving portion 25 is moved up and down in the axial direction, and the distance between the upper spring receiving portion 25 and a partition member 60 described later is changed. The initial spring length of the spring 14 is adjusted, and the spring force of the suspension spring 14 is adjusted. The small-diameter shaft portion 21 </ b> A of the adjusting bolt 21 is provided with an air vent hole 21 </ b> C that communicates with the hollow portion 21 </ b> B and the inner space of the outer tube 11. Further, a sealing screw 22 or the like for blocking communication between the outer tube 11 and the outside is attached to the upper end side of the hollow portion 21B.

  The outer periphery on the upper end side of the piston rod 15 is screwed and fixed to the lower inner periphery of the above-described threaded cylindrical lifting nut 23 so as to be coaxial with the outer tube 11. The piston rod 15 extends toward the inner tube 12 and has a length that reaches an inner space of a cylinder tube 51 (described later) provided upright on the inner tube 12. A piston 40 that slides in the cylinder tube 51 is attached to the lower end of the piston rod 15.

The piston 40 is configured to be movable along with the outer tube 11 in the cylinder tube 51 in the sliding operation of the outer tube 11 and the inner tube 12 by being attached to the piston rod 15.
The piston 40 is formed of a cylindrical body that is vertically partitioned by a wall 40E. The upper rod mounting portion 40A to which the lower end side outer periphery of the piston rod 15 is screwed is formed on the upper inner periphery, and the piston rod 15 is disposed on the lower inner periphery. Is provided with a lower rod mounting portion 40B on which the outer periphery of the upper end side of the extension rod 16 is screwed. The extension rod 16 has the same outer diameter as the piston rod 15 and is inserted into a guide tube 52 provided in the inner tube 12. A piston ring 40 </ b> C that maintains a liquid-tight state with the inner periphery of the cylinder tube 51 is provided on the lower outer periphery of the piston 40. The piston 40 in the present embodiment will be described assuming that it does not include a flow path hole through which the hydraulic oil K flows in the vertical direction as the piston 40 slides in the cylinder tube 51 as in the prior art.
Note that the piston rod 15 and the extension rod 16 may be constituted by a single piston rod without being divided into the piston rod 15 and the extension rod 16 as described above. In this case, the piston may be configured so that the piston rod can penetrate, and a fixing means for fixing the piston may be provided on the outer periphery of the piston rod.

Hereinafter, the inner tube 12 will be described.
The inner tube 12 is a cylinder of a predetermined length formed with a constant outer diameter from the upper end to the lower end, and a cylinder holder 50 that forms the bottom of the inner tube 12 and a cylinder on which the outer periphery of the piston 40 slides. A cylindrical tube 51, a guide tube 52 that guides the extension rod 16 extended from the piston 40, and a damping force generator 140 that generates a damping force in the front fork 10.

The axle holder 50 is a shaft body whose lower side is formed into a rectangular shape and whose upper side is formed into a cylindrical shape, and an axle support portion 50A that supports the axle on the lower side and an assembly portion 50B that is assembled to the inner tube 12. With.
The axle support portion 50 </ b> A is formed with an axle through hole 50 a that penetrates in the direction orthogonal to the axis of the axle holder 50. In the axle through hole 50a, a split portion 50b extends from the inner periphery toward the lower end surface of the axle holder 50. The cut portion 50b clamps and fixes the axle by tightening a bolt (not shown) screwed into a screw hole 50c formed so as to be orthogonal to the extending direction of the cut portion 50b below the axle through hole 50a.

The assembly portion 50B is formed in a substantially cylindrical shape, and has a screw portion 53a to be screwed to the outer periphery on the lower end side of the inner tube 12 on the outer periphery, and the axle holder 50 and the inner tube on the lower side of the screw portion 53a. When the inner tube 12 is screwed onto the axle holder 50, an annular abutment that abuts against the tip of the inner tube 12 is maintained. A portion 53c is provided.
Therefore, the axle holder 50 has the inner circumference of the inner tube 12 and the outer circumference of the axle holder 50 described above by screwing the inner tube 12 into the threaded portion 53a until the lower end of the inner tube 12 abuts against the abutting portion 53c. And is fixed to the axle holder 50 in a liquid-tight state.

A cylinder tube fixing portion 54a and a guide tube fixing portion 54b for fixing the lower end side of the cylinder tube 51 and the lower end side of the guide tube 52 are provided on the inner peripheral side of the assembly portion 50B.
The upper cylinder tube fixing portion 54a and the lower guide tube fixing portion 54b are formed as stepped holes that are concentric with the axis of the inner tube 12 and reduce in diameter toward the bottom.
The cylinder tube fixing portion 54a is a screw hole having a size smaller than the inner diameter of the axle holder 50 so as to have a gap e1 between the inner peripheral surface 53d of the assembly portion 50B of the axle holder 50 and the outer periphery 51a of the cylinder tube 51. Formed as.
The outer periphery of one end of the cylinder tube 51 is screwed into this threaded hole, and the lower end is abutted against the annular abutting portion 54c formed in an annular shape between the cylinder tube fixing portion 54a and the guide tube fixing portion 54b. 50. The annular abutment portion 54c is formed so as to be positioned below the abutment portion 53c of the axle holder 50 described above.

  The guide tube fixing portion 54b is formed as a screw hole having a size smaller than the inner diameter of the cylinder tube 51 so as to have a gap e2 between the inner peripheral surface of the cylinder tube 51 and the outer periphery of the guide tube 52. The outer periphery of one end of the guide tube 52 is screwed into this screw hole, and the end is abutted against the lowermost bottom portion 54d and is erected in the axle holder 50. The lowermost bottom portion 54d is formed so as to be positioned below the above-described annular abutting portion 54c.

  A guide collar 52 </ b> A that allows the extension rod 16 to penetrate is attached to the upper end side of the guide tube 52. On the inner periphery of the guide collar 52A, a sealing member 52a that enables sliding in a liquid-tight state with the outer periphery of the extension rod 16 is provided. The sealing member 52a is made of a rubber seal member such as an O-ring. The outer periphery of the guide collar 52 </ b> A has a petal shape in a sectional view and is supported on the inner periphery of the cylinder tube 51. The extension rod 16 is shorter than the cylinder tube 51 and is set to a length that does not come out of the guide tube 52 even when the front fork 10 is fully extended.

A through hole 55 that opens to the inner peripheral side of the guide tube 52 is formed on the lowermost bottom portion 54d side where the lower end of the guide tube 52 abuts. Through the through hole 55, the inner peripheral side of the guide tube 52 communicates with the outside air outside the front fork 10, and the pressure in the guide tube 52 becomes the same pressure as the atmospheric pressure.
That is, since the extension rod 16 inserted into the guide tube 52 penetrates into and out of the cylinder tube 51, even if the piston 40 moves in the cylinder tube 51, the piston rod 15 moves in and out of the cylinder tube 51. Since the extension rod 16 also moves in and out of the cylinder tube 51 by the amount, the volume in the cylinder tube 51 becomes constant regardless of the damping operation of the piston 40, and the pressure in the hydraulic oil chamber A does not change, so that the damping operation is performed. It can be stabilized.

  A partition member 60 that partitions the inside of the inner tube 12 into an upper air chamber SA and a lower hydraulic oil chamber A is fixedly attached to the upper end of the cylinder tube 51 with respect to the cylinder tube 51. The partition member 60 includes a base portion 60D and a cylindrical portion 60C. The partition member 60 includes a guide portion 60A through which the above-described piston rod 15 penetrates at the inner periphery of the center hole of the base portion 60D. An annular body is provided that includes a sealing portion 60B that closely adheres along the inner peripheral surface and seals liquid-tightly. The guide portion 60A is provided with a seal member 60a that allows sliding in a liquid-tight state with the outer periphery of the piston rod 15, and the sealing portion 60B has a seal member that maintains liquid-tightness with the inner periphery of the inner tube 12. 60b is provided. A flow hole 61 is formed on the upper side of the cylindrical portion 60C. The flow hole 61 communicates from the space surrounded by the base portion 60 </ b> D of the partition member 60 and the cylinder tube 51 to the space surrounded by the inner periphery of the inner tube 12 and the outer periphery of the cylinder tube 51, and the mutual flow of the hydraulic oil K. Is acceptable. The flow hole 61 may be provided in the cylinder tube 51 as long as it is outside the moving range in which the piston 40 moves in the cylinder tube 51, that is, above the stroke range of the piston 40. Further, the inner tube 12 is provided with a lubricating hole 12 a that opens in a gap with the outer tube 11 above the partition member 60. This lubricating hole 12 a allows lubricating oil stored in the air chamber SA separately from the above-described hydraulic oil K to flow between the outer tube 11 and the inner tube 12.

  The partition member 60 is fixed to the cylinder tube 51 by screwing the inner periphery of the cylinder portion 60 </ b> C to the outer periphery on the upper end side of the cylinder tube 51. Between the bottom surface of the base portion 60D of the cylindrical portion 60C and the above-described piston 40, a buffer material for buffering the collision between the piston 40 and the partition member 60 when the front fork 10 is fully extended, for example, rebound A spring or the like is inserted.

Therefore, by attaching the partition member 60 to the cylinder tube 51 and closing the internal space of the cylinder tube 51, the hydraulic oil chamber A has a pressure side oil chamber 127 </ b> A at a lower portion than the piston 40 inside the cylinder tube 51 and an inner side. The cylinder 12 is divided into a portion defined by the inner periphery of the tube 12 and the outer periphery of the cylinder tube 51, and an extension side oil chamber 127 </ b> B that is an upper portion of the piston 40 inside the cylinder tube 51.
On the side of the axle holder 50, a pressure side oil chamber flow path 57A for flowing the working oil K from the pressure side oil chamber 127A and an extension side oil chamber flow path 57B for flowing the working oil K from the extension side oil chamber 127B are provided. And are open.
The pressure side oil chamber flow path 57A and the extension side oil chamber flow path 57B constitute a part of the external flow path that allows the working oil to flow outside the cylinder tube 51 described above.
In the front fork 10 of the present embodiment, the hydraulic oil K is sealed between the hydraulic oil chamber A, the pressure side oil chamber flow path 57A, and the extension side oil chamber flow path 57B.

  As shown in FIG. 2, the damping force generator 140 includes a cylinder Ma formed integrally with the axle holder 50 so as to protrude from the side of the axle holder 50 corresponding to the compression side oil chamber flow path 57 </ b> A, and an extension body. Corresponding to the side oil chamber flow path 57B, the communication path Mb is formed integrally with the axle holder 50, and a damping force generation unit 140A. The cylindrical body Ma is formed with a cylindrical valve accommodating hole 114A having one end opening. The valve housing hole 114A communicates with the pressure side oil chamber flow path 57A at the bottom 114b, and is connected to the communication path Mb having the extension side oil chamber flow path 57B at the upper side of the opening end side opposite to the bottom 114b. That is, the pressure side oil chamber flow path 57A, the valve housing hole 114A, and the extension side oil chamber flow path 57B constitute an oil chamber flow path that connects the pressure side oil chamber 127A and the extension side oil chamber 127B.

  The damping force generation unit 140A is provided on the compression side damping force generation unit 250 provided on the compression side oil chamber 127A side and on the extension side oil chamber 127B side in order to generate a damping force when the front fork 10 is compressed and extended. The extension side damping force generator 260 is disposed in series, and includes a damping force adjustment unit 270 that enables adjustment of the damping force during compression and extension.

The damping force generation unit 140A includes a cylindrical valve piece 141 as a base, and includes a compression side damping force generation unit 250, an extension side damping force generation unit 260, and a damping force adjustment unit 270.
The valve piece 141 has a large-diameter portion 142 made of a large-diameter cylinder and a small-diameter portion 143 made of a small-diameter cylinder that projects coaxially from one end of the large-diameter portion 142. In the following description, the large diameter portion side in the axial direction of the valve piece 141 will be described as one end side, and the distal end side of the small diameter portion 143 will be described as the other end side.
The valve piece 141 includes a through hole that extends from the tip of the small diameter portion 143 to the large diameter portion 142. The through hole is a bypass passage 141 </ b> A that bypasses a later-described compression-side damping force generation unit 250 and an extension-side damping force generation unit 260 provided on the outer periphery of the small-diameter portion 143. The large-diameter portion 142 of the valve piece 141 is provided with a plurality of flow passage holes 142A that penetrate in the thickness direction of the cylindrical wall portion and allow the hydraulic oil K to flow in and out through the wall portion. 143 includes a plurality of flow passage holes 143A penetrating inward and outward in the middle in the axial direction, a needle hole 143B constituting a later-described damping force adjusting portion 270 on the inner peripheral side, and a screw portion 143C on the outer periphery on the front end side. Provided.

On the outer periphery of the small diameter portion 143, an extension side damping force generation unit 260 is provided on one end side, and a compression side damping force generation unit 250 is provided on the other end side. For convenience of explanation, the extension side damping force generator 260 will be described.
The extension-side damping force generator 260 includes a disk-like extension-side flow restricting body 160 having an extension-side channel 160A and a compression-side channel 160B that regulate the flow in the compression-side stroke and the extension-side stroke, and the extension-side damping unit 260 extends in the compression-side stroke. The side flow path 160A is blocked, the expansion side damping valve 161 that generates a damping force by controlling the flow rate of the hydraulic oil K flowing out from the expansion side flow path 160A in the expansion side stroke, and the pressure side flow path 160B is closed in the expansion side stroke. And a pressure side check valve 152 for controlling the flow rate of the hydraulic oil K flowing out from the pressure side flow path 160B in the pressure side stroke and generating a damping force in the pressure side stroke.
The expansion side flow regulating body 160, the expansion side damping valve 161, and the pressure side check valve 152 are arranged in order from the large diameter portion 142 side of the valve piece 141, and the pressure side check valve 152, the expansion side flow restriction body 160, and the expansion side damping valve 161 have a small diameter. It is attached to the outer periphery of the part 143.

A collar 163, a spring 164, and a spring seat 165 are provided between the extension side flow regulating body 160 and the stepped surface 141 </ b> C on one end side of the valve piece 141.
The collar 163 is a cylindrical tube and is inserted in the outer periphery of the small diameter portion 143. The collar 163 passes through the pressure side check valve 152, one end abuts against the step surface 141C, and the other end contacts the expansion side flow regulating body 160. By contacting, the position in the small diameter part 143 of the expansion side flow regulating body 160 is positioned. One end of the spring 164 is seated on the pressure side check valve 152, and the other end is seated on the step surface 141 </ b> C via a spring seat 165 provided on the outer periphery of the collar 163. Energize towards.
The urging force of the spring 164 to the pressure side check valve 152 becomes a resistance of the hydraulic oil K flowing through the pressure side flow passage 160B of the extension side flow regulating body 160 in the pressure side stroke, and generates a damping force in the operation of the front fork 10. .

  A shim 166 is provided adjacent to the other end side of the valve piece 141 of the extension side damping valve 161. The shim 166 secures a margin for bending so that the center plate 145 provided adjacent to the extension side damping force generator 260 does not hinder the operation of the extension side damping valve 161. A center plate 145 is inserted adjacent to the other end of the valve piece 141 of the shim 166.

  The center plate 145 is an annular member that is inserted on the outer periphery of the small diameter portion 143. The center plate 145 has an annular recess 145A that is recessed in the outer diameter direction at the center portion in the thickness direction of the inner periphery, and a plurality that communicates from the annular recess 145A to the outer periphery. Channel passage hole 145B. The center plate 145 is assembled so that the annular recess 145A on the inner peripheral side surrounds the plurality of flow path holes 143A of the small diameter portion 143. This assembly position is adjusted by a shim 166, for example.

  A shim 167 is inserted into the small diameter portion 143 adjacent to the center plate 145 on the other end side of the valve piece 141 of the center plate 145. The shim 167 ensures a bending margin of the compression side damping valve 151 so that the center plate 145 does not interfere with the operation of the compression side damping valve 151 with respect to the compression side damping valve 151 of the compression side damping force generation unit 250. A compression-side damping force generator 250 is provided adjacent to the other end of the valve piece 141 of the shim 167.

The compression-side damping force generation unit 250 includes a disk-shaped compression-side flow restricting body 150 having a compression-side flow path 150A and an expansion-side flow path 150B that restrict the flow rate in the compression-side stroke and the extension-side stroke, and a pressure-side flow in the extension-side stroke. The pressure-side damping valve 151 that generates a damping force by controlling the flow rate of the hydraulic oil K flowing out from the pressure-side flow path 150A in the pressure-side stroke, and the expansion-side flow path 150B in the pressure-side stroke are closed. And an extension check valve 162 that generates a damping force in the extension stroke by controlling the flow rate of the hydraulic oil K flowing out of the extension passage 150B.
The compression side damping force generator 250 is equipped with a shim 167, a compression side damping valve 151, a compression side flow regulating body 150, and an extension side check valve 162 in order from the center plate 145 side.

  A cylindrical collar 153 penetrating the extension side check valve 162 is inserted on the distal end side of the pressure side flow regulating body 150 of the small diameter portion 143 and is provided so as to cover the outer periphery of the collar 153. A spring 154 on which one end side is seated and a spring seat 155 on which the other end side of the spring 154 is seated are provided. Then, the nut 200 is screwed into the screw portion 143C, and the nut 200 is tightened until it abuts against the collar 153, whereby the compression side damping force generation unit 250 and the extension side damping force generation unit 260 are integrated with the outer peripheral side of the valve piece 141. Assembled into. By the tightening of the nut 200, a biasing force is applied by which the spring 154 biases the extension side check valve 162 toward the compression side flow regulating body 150. The biasing force to the extension side check valve 162 by the spring 154 becomes a resistance of the hydraulic oil K flowing through the extension side flow path 150B of the pressure side flow regulating body 150 in the extension side stroke, and generates a damping force in the operation of the front fork 10. Let

  The damping force generation unit 140A that is assembled as described above is accommodated with the nut 200 facing the bottom 114b in the axial direction of the valve accommodation hole 114A. When the damping force generating unit 140A is housed in the valve housing hole 114A, the seal member 160C; 150C provided on the outer periphery of the extension side flow restricting body 160 and the outer periphery of the pressure side flow restricting body 150 is inside the valve housing hole 114A. Close contact with the circumference. Accordingly, all of the hydraulic oil K flowing from the pressure side oil chamber flow path 57A and the expansion side oil chamber flow path 57B to the valve accommodating hole 114A is transferred to the expansion side flow path 160A or the pressure side flow path 160B of the expansion side flow regulating body 160. It flows through the expansion side flow path 150B or the pressure side flow path 150A of the flow regulating body 150 and a bypass flow path 141A described later.

  In the present embodiment, the space between the pressure-side flow regulating body 150 and the pressure-side oil chamber passage 57A side in the valve housing hole 114A is defined as a pressure-extended flow passage 146A communicating with the pressure-side oil chamber 127A, and the extension-side flow rate in the valve housing hole 114A. The space between the regulating body 160 and the extension side oil chamber channel 57B side is defined as a pressure expansion common channel 146B communicating with the extension side oil chamber 127B, and the annular space around the center plate 145 is defined as an intermediate chamber 149. The intermediate chamber 149 is a space common to an intermediate portion between the compression side damping valve 151 and the compression side check valve 152 and an intermediate portion between the extension side attenuation valve 161 and the extension side check valve 162. In the intermediate chamber 149, one end side of a hydraulic oil passage 115m communicating with a pressure adjusting oil reservoir chamber (hereinafter referred to as an oil reservoir chamber) 132 for adjusting the pressure of the hydraulic oil chamber A is opened. In the intermediate chamber 149 formed in the damping force generator 140, the hydraulic oil K from the pressure side oil chamber channel 57A side in the compression side stroke to the extension side oil chamber channel 57B direction, and the above direction in the extension side stroke The hydraulic oil K in the opposite direction passes in common, and one end of the return flow path T and the pressure suppression flow path S communicates.

  Therefore, in the valve accommodating hole 114A, the pressure side flow path and the extension side flow as external flow paths through which the hydraulic oil K flows in the pressure side stroke and the extension side stroke by the pressure side damping force generation part 250 and the extension side damping force generation part 260. A road is formed. The pressure side flow path for moving the hydraulic oil K from the pressure side oil chamber 127A to the expansion side oil chamber 127B in the pressure side stroke is the pressure expansion common flow path 146A, the intermediate chamber 149, the pressure side flow path 150A, the pressure side flow path 160B, and the pressure expansion common use. The expansion side flow path formed by the flow path 146B and used to move the hydraulic oil K from the expansion side oil chamber 127B to the pressure side oil chamber 127A in the expansion side stroke is the pressure expansion common flow path 146B, the expansion side flow path 160A, and the intermediate chamber. 149, the expansion side flow path 150B, and the pressure expansion common flow path 146A.

  FIGS. 3A and 3B show an enlarged view of the damping force adjusting unit and a partially enlarged view of the extension side damping force adjusting unit constituting the damping force generating device 140. FIG. As shown in the figure, the damping force adjusting portion 270 is provided on the inner peripheral side of a valve piece 141 made of a cylindrical body. The valve piece 141 includes a cylindrical hollow portion (large diameter hollow portion) 142 a in the large diameter portion 142 and a cylindrical hollow portion (small diameter hollow portion) 143 a in the small diameter portion 143. In the large-diameter hollow portion 142a, an opening 144B of the small-diameter hollow portion 143a is formed in a step portion 143D formed on the small-diameter portion 143 side. The large-diameter hollow portion 142a and the small-diameter hollow portion 143a of the valve piece 141 bypass the compression-side damping force generation unit 250 and the expansion-side damping force generation unit 260, and the hydraulic oil is supplied to the compression-side oil chamber 127A and the expansion-side oil chamber 127B. A bypass channel 141A that allows K to flow is formed. The bypass channel 141A is provided with damping force adjusting means.

  The damping force adjuster 270 includes a needle valve mechanism formed of a needle hole 143B formed in the small-diameter hollow part 143a and a needle shaft 272 provided to be movable back and forth with respect to the needle hole 143B, and a large-diameter hollow part 142a. The needle valve mechanism is composed of an opening 144B in which the small-diameter hollow portion 143a is opened and a flow rate adjusting body 279 provided to be movable forward and backward with respect to the opening 144B. The needle hole 143B is formed as a through-hole whose inner diameter is smaller than the inner diameter of the small-diameter hollow portion 143a from the middle portion in the small-diameter hollow portion 143a to the tip, and an opening 144A is formed in the small-diameter hollow portion 143a. The opening 144A and the needle shaft 272 constituting the needle valve mechanism are inserted into the small diameter hollow portion 143a from the large diameter portion 142 side. The needle shaft 272 includes a needle valve 272A that is tapered on the front end side, and a needle shaft support 277 that supports the needle shaft 272 on the rear end side. The needle shaft support 277 has a needle shaft 272 passing through a needle shaft through hole 277A formed on the center side, and is engaged with a flange portion 274 formed at one end of the needle shaft 272 and an engagement groove 275. It is held between the members 276. The needle shaft support 277 is formed with a screw hole 277B and a guide hole 277C penetrating in the axial direction. The needle shaft 272 is provided with an opening 144B and a flow rate adjusting body 279 constituting a needle valve mechanism. The flow rate adjusting body 279 is formed of a needle shaft sliding hole 279A through which the needle shaft 272 penetrates with a slidable gap x while maintaining a liquid-tight state by the sealing member 280, and a taper whose tip direction is a small diameter. By providing the tapered surface 279B on the outer periphery and adjusting the gap n2 between the opening 144B and the tapered surface 279B, the flow rate flowing into the small-diameter hollow portion 143a from the large-diameter portion 142 side is adjusted. A disc-shaped base portion 278 having a screw hole 278B penetrating in the axial direction and a guide hole 278C is integrally provided on the rear end side of the flow rate adjusting body 279. In a state where the screw hole 278B of the base portion 278 and the shaft center of the guide hole 277C of the needle shaft support body 277 and the guide hole 278C of the base portion 278 and the shaft center of the screw hole 277B of the needle shaft support body 277 are aligned with each other, A compression side damping force adjustment bolt 170 that enables adjustment of the damping force and an extension side damping force adjustment bolt 180 that enables adjustment of the extension side damping force are mounted.

In the compression side damping force adjusting bolt 170, a guide shaft 171 formed on the distal end side is inserted into a guide hole 278C of the base portion 278, and a screw shaft 172 formed on the head portion 170A side is inserted into the screw hole 277B of the needle shaft support 277. Screwed.
In the extension side damping force adjusting bolt 180, a screw shaft 181 formed on the distal end side is screwed into a screw hole 278B of the base portion, and a guide shaft 182 formed on the head portion 180A side is a guide hole 278C of the needle shaft support 277. Is inserted. Thereby, the compression side damping force adjustment bolt 170 and the extension side damping force adjustment bolt 180 are integrated with the needle shaft 272 and the flow rate adjusting body 279, and the needle side shaft 272 is moved in the axial direction by rotating the compression side damping force adjustment bolt 170. The flow rate adjusting body 279 is configured to be able to advance and retract along the needle shaft 272 by rotating the extension side damping force adjusting bolt 180.

The compression side damping force adjustment bolt 170 and the extension side damping force adjustment bolt 180 are held by a cap 205 including an inner cap 210 and an outer cap 220. The inner cap 210 is formed with accommodation holes 211A and 211B for individually accommodating the head portion 170A of the compression side damping force adjustment bolt 170 and the head portion 180A of the extension side damping force adjustment bolt 180. The accommodation holes 211A and 211B of the inner cap 210 are provided on the same plane in a sectional view including the central axis. The head portion 170A of the compression side damping force adjustment bolt 170 and the head portion 180A of the extension side damping force adjustment bolt 180 are respectively provided with sealing members 173 and 183 that maintain a liquid-tight state with the accommodation holes 211A and 211B. Through holes 212A to 212C that penetrate from the outer periphery of the inner cap 210 in a direction orthogonal to the axial direction are formed in the accommodation holes 211A and 211B. The through holes 212A to 212C accommodate the spring 213 and the check ball 214, respectively, and the check ball 214 is provided so as to be positioned on the opening side of the accommodation holes 211A and 211B. A plurality of check balls 214 are formed along the circumferential direction on the outer periphery of the head portion 170A of the compression side damping force adjustment bolt 170 and the outer periphery of the head portion 180A of the extension side damping force adjustment bolt 180 by the biasing force of the spring 213. By fitting in one of the recesses 174; 184, the compression side damping force adjustment bolt 170 and the extension side damping force adjustment bolt 180 are supported, and the compression side damping force adjustment bolt 170 and the extension side damping force are adjusted to adjust the damping force. When the adjustment bolt 180 is rotated, a detent mechanism that maintains the adjustment positions of the compression side damping force adjustment bolt 170 and the extension side damping force adjustment bolt 180 is configured.
The damping force adjusting portion 270 integrated with the cap 205 is inserted into the small diameter hollow portion 143a of the valve piece 141 while inserting the needle shaft 272 into the outer peripheral screw portion of the large diameter portion 142 of the valve piece. To be integrated with the valve piece 141. At this time, the needle valve 272A of the needle shaft 272 creates a predetermined gap n1; n2 with respect to the opening 144A of the needle hole 143B, and the tapered surface 279B of the flow rate adjusting body 279 with respect to the opening 144B of the bypass channel 141A. Adjusted to
The damping force generation unit 140A is accommodated in the valve accommodation hole 114A as described above.

  Therefore, the damping force generation unit 140A is configured such that the flow rate from the extension side oil chamber 127B pressurized by the piston 40 in the cylinder during the extension stroke of the front fork 10 toward the compression side oil chamber 127A is the flow rate inserted in the needle shaft 272. By adjusting the advance / retreat amount of the tapered surface 279B of the adjusting body 279 with respect to the opening 144B with the expansion side damping force adjusting bolt 180, the adjustment is performed by changing the gap n2 between the tapered surface 279B and the opening 144B. That is, when the tapered surface 279B of the flow rate adjusting body 279 is close to the opening portion 144B of the small diameter portion 143, the gap between the two becomes small, the flow rate flowing through the bypass channel 141A is reduced, and a large damping force is obtained. On the other hand, the tapered surface 279B of the flow rate adjusting body 279 is separated from the opening 144B of the small diameter portion 143, so that the gap between the two becomes large and the flow rate flowing through the bypass channel 141A increases, and a small damping force is generated. Will be obtained.

As shown in FIG. 2, the intermediate chamber 149 of the valve accommodating hole 114A accommodating the damping force generating unit 140A is as shown in FIG.
One end of a hydraulic oil guide tube 115 projecting downward from the damping force generator 140 side is connected, and the intermediate chamber 149 and the oil reservoir chamber 132 are communicated with each other through the hydraulic oil flow passage 115m of the hydraulic oil guide tube 115. .
The oil reservoir chamber 132 is formed in a sub tank 130 provided in the axle holder 50 separately from the hydraulic oil chamber A and the valve housing hole 114A.

That is, the sub tank 130 is connected to the intermediate chamber 149 through the hydraulic oil guide pipe 115 for the hydraulic oil K. The hydraulic oil guide pipe 115 includes a hydraulic oil flow path 115 m that allows the hydraulic oil K to flow in and out from the intermediate chamber 149 toward the oil reservoir chamber 132. The hydraulic oil flow path 115m communicates with the oil reservoir chamber 132 through the lateral hole 115n. The sub-tank 130 constitutes a temperature compensation means Q, which is made of, for example, a cylindrical body, has an internal space formed in a cylindrical shape, and can be sealed with a cap (not shown). Inside the sub tank 130, a free piston 133 is provided that is movable along the axial direction while maintaining a liquid-tight state with the inner peripheral surface of the sub tank 130. The free piston 133 partitions the inside of the cylindrical sub tank 130 so that the oil reservoir chamber 132 is formed on the side of the horizontal hole 115n and the pressurizing chamber 134 is formed on the cap 135 side. The sub tank 130 absorbs expansion associated with the temperature rise of the hydraulic oil K. The lower end of the hydraulic oil guide tube 115 is opened and sealed with a seal member 306 of the flow path switching device 300 described later.
The pressurizing chamber 134 is a closed space formed between the free piston 133 and the cap, and a gas having a predetermined pressure is sealed therein.
The volume of the oil reservoir chamber 132 in the sub tank 130 changes depending on the position of the pressure adjusting free piston 133 that is displaced by the pressure balance between the pressure of the gas sealed in the pressurizing chamber 134 and the pressure of the intermediate chamber 149. The oil reservoir chamber 132 has a pressure adjustment function based on a change in volume, and the internal pressure is maintained at a positive pressure by the pressure pressurized from the pressurizing chamber 134 via the free piston 133. As a result, the intermediate chamber 149 communicating with the oil reservoir chamber 132, the hydraulic oil chamber A, and the like are also maintained at positive pressure, thereby preventing cavitation during the damping operation in the compression side stroke and the extension side stroke. Further, when the front fork 10 is operated, the temperature of the hydraulic oil K in the intermediate chamber 149 and the hydraulic oil chamber A rises and the volume of the hydraulic oil K expands. When the pressure due to the expansion of the hydraulic oil K becomes higher than the pressure in the pressurizing chamber 134, it flows into the oil reservoir chamber 132 and pushes the free piston 133 to increase the volume of the oil reservoir chamber 132. By absorbing the oil K, temperature compensation during operation is performed.
Further, when the front fork 10 is not operating, the temperature of the hydraulic oil K in the intermediate chamber 149 and the hydraulic oil chamber A decreases, and the volume of the hydraulic oil K contracts. When the pressure due to the contraction of the hydraulic oil K becomes lower than the pressure in the pressurizing chamber 134, the free piston 133 pressurizes the oil reservoir chamber 132 and flows the hydraulic oil K from the oil reservoir chamber 132 to the intermediate chamber 149. Thus, the volume of the oil reservoir chamber 132 is reduced. Although the pressure in the hydraulic oil chamber A is lower than the pressure in the pressurizing chamber 134, the free piston 133 pressurizes the hydraulic oil K in the oil reservoir chamber 132. Since the hydraulic oil K in the oil reservoir chamber 132 flows into the intermediate chamber 149 and the hydraulic oil chamber A while maintaining a positive pressure state, the occurrence of cavitation of the hydraulic oil K is always suppressed.

The hydraulic oil flow path 115m is communicated between a pressure suppression flow path S that allows the flow of the hydraulic oil K from the intermediate chamber 149 to the oil reservoir chamber 132, and the oil reservoir chamber 132 to the intermediate chamber 149. A flow path switching device 300 that switches the flow direction between the return flow path T that allows the flow of the hydraulic oil K and the pressure suppression flow path S and the return flow path T is provided. The flow path switching device 300 is configured to control the flow rate of the hydraulic oil K in front of other than the pressure side stroke and the extension side stroke based on the pressure of the hydraulic oil K flowing in the direction of the oil reservoir 132 in the pressure side stroke and the extension side stroke. It functions as hydraulic fluid flow rate control means Z that restricts the amount of hydraulic fluid when the fork is not operating to a smaller amount than when hydraulic fluid flows out .
The flow path switching device 300 as the hydraulic oil flow control means Z is provided in the flow path switching device accommodation hole 116 that extends from the outside of the axle holder 50 so as to communicate with the hydraulic oil flow path 115m. A threaded portion 116 </ b> A for fixing the flow path switching device 300 is formed on the inner periphery of the flow path switching device accommodation hole 116.

4A and 4B are an exploded perspective view and an assembled cross-sectional view of an embodiment of the flow path switching device 300 as the hydraulic oil flow control means Z. FIG.
The channel switching device 300 includes a check valve mechanism that switches between the pressure suppression channel S and the return channel T. The check valve mechanism includes a flow of hydraulic oil K through the pressure suppression flow path S from the intermediate chamber 149 toward the oil reservoir chamber 132 in accordance with the pressure difference between the intermediate chamber 149 and the oil reservoir chamber 132, and the oil reservoir chamber. The flow of the hydraulic oil K through the return flow path T from 132 to the intermediate chamber 149 is switched.
The flow path switching device 300 includes a valve case 301 that houses a check valve mechanism, a spring 302 that constitutes the check valve mechanism, a check valve 303, a guide pin 304 that guides the operation of the check valve 303, a spring 302 together with the valve case 301, A check valve 303 and a guide pin 304 are housed therein, and a valve bolt 305 that functions as an attachment member for attaching the flow path switching device 300 to the flow path switching device housing hole 116 is provided.

  The valve case 301 is a cylindrical tubular body fitted in a hydraulic oil guide tube 115 of hydraulic oil K that extends the top hole 301C of the valve case 301 in the vertical direction so as to face the intermediate chamber 149. A female screw part 301A is provided on the inner periphery on the opening end side, and a top hole 301C is provided on the center side of the top part 301B. The upper end of the spring 302 is seated on the top portion 301 </ b> B, and the lower end side is seated on the flange portion 303 </ b> B of the check valve 303.

The check valve 303 is provided with a flange portion 303B that protrudes outward from the lower end of a cylindrical tube portion 303A having an outer diameter that can be accommodated on the inner peripheral side of the spring 302.
A hole 303C having a diameter through which the guide pin 304 cannot pass is provided on the center side of the top portion 303D.
The lower end of the flange 303B is formed as a seal surface 303b of the check valve mechanism. The seal surface 303b is formed in a tapered shape or a spherical shape. The outer peripheral surface 303d of the collar portion 303B is formed into a petal shape that periodically repeats unevenness along the circumferential direction, and the return flow path T is formed by the recessed portion. As shown in FIGS. 4 (a) and 4 (c), the return flow path T of the recessed portion of the flange 303B causes the hydraulic oil K to flow out from the oil reservoir chamber 132 to the intermediate chamber 149 when the piston 40 is not operating. It is formed as a throttle channel that is opened by pressure and through which hydraulic oil K flows from the oil reservoir chamber 132 toward the intermediate chamber 149. As described above, the outline of the outer peripheral surface 303d when the collar portion 303B is viewed in the axial direction is formed in a petal shape, so that a minute gap between the outer periphery of the guide pin 304 and the inner peripheral surface 303a of the check valve 303 is formed. The hydraulic oil K flowing in the return flow path T can be made larger than the flow rate of the hydraulic oil K flowing through the pressure suppression flow path S formed by J. The sealing surface 303b is seated on the upper inner peripheral edge 319A of the seating cylinder 319.

  The guide pin 304 forms an annular minute gap J having a predetermined thickness between the outer peripheral surface 304 a and the inner peripheral surface 303 a of the check valve 303. The minute gap J is set to have an opening smaller than the flow passage cross section of the return flow passage T, and restricts the flow rate so that the pressure generated in the intermediate chamber 149 by the operation of the piston 40 is not transmitted to the oil reservoir chamber 132. Thus, a pressure suppression channel S that suppresses the transmission of pressure is configured. The pressure suppression flow path S formed by the minute gap J flows from the intermediate chamber 149 toward the oil reservoir chamber 132 at a static pressure by opening and closing the check valve 303, and from the intermediate chamber 149 to the oil reservoir chamber at a dynamic pressure. The cross-sectional area of the minute gap J and the length of the minute gap J in the axial direction are set so as not to flow toward 132. The static pressure refers to, for example, the pressure corresponding to the volume expansion of the hydraulic oil K when the hydraulic oil K in the hydraulic oil chamber A or the intermediate chamber 149 rises in temperature. Further, the dynamic pressure difference refers to the pressure transmitted to the intermediate chamber 149 by the operation of the piston 40. Therefore, on the intermediate chamber 149 side, the volume change due to the temperature change of the hydraulic oil K is transmitted to the oil reservoir chamber 132 via the hydraulic oil K in the minute gap J.

In the seating cylinder 319, a male thread part 312 at the upper outer periphery is screwed into a female thread part 301A of the valve case 301, and an abutting part 317 that abuts the lower end of the valve case 301 is formed in the middle part of the outer periphery of the seating cylinder 319. A through hole 318 that penetrates in the radial direction below the contact portion 317 of the seating cylinder 319 and faces the above-mentioned lateral hole 115n is formed. The bottom 316 of the seating cylinder 319 is fixed to the tip of the valve bolt 305. The valve bolt 305 is screwed into the screw portion 116A on the lower opening side of the hydraulic oil guide tube 115 and supports the seating cylinder 319, a seal groove 314, a flange portion 313, and a seal member 306. The nut portion 311 as a whole is formed so as to protrude in the central axis direction of the hydraulic oil guide tube 115.
In this case, the inner upper surface of the bottom portion 316 is recessed in a weight shape, and the lower end of the guide pin 304 is held in contact with the center side thereof. The inner periphery of the circular hole of the seating cylinder 319 is formed to have a dimension that allows insertion with a sufficient gap from the outer periphery of the guide pin 304.
The upper inner peripheral edge 319A (FIG. 4B) of the seating cylinder 319 has a circular shape, and the seal surface 303b of the check valve 303 can be in close contact therewith.
The cross-sectional shape in the depth direction of the circular hole of the seating cylinder 319 may be any shape such as a circle or a petal shape, and at least the upper inner peripheral edge 319A of the seating cylinder 319 is sealed with the seal surface 303b of the check valve 303. It suffices if it is formed in a circular shape as possible.

The flow path switching device 300 as the hydraulic fluid flow control means Z is assembled as follows as an example.
First, the upper end side of the spring 302 is seated and accommodated in the top portion 301 </ b> B of the valve case 301. Next, the cylindrical portion 303 </ b> A is inserted into the inner peripheral side of the spring 302 at the lower end side of the spring 302 accommodated in the valve case 301, and the flange portion 303 </ b> B of the check valve 303 is seated at the other end of the spring 302. Next, the guide pin 304 is inserted into the inner periphery of the check valve 303, and the male pin portion 312 of the valve bolt 305 is inserted into the valve case 301 while the guide pin 304 protruding from the check valve 303 is inserted into the seating cylinder 319 of the valve bolt 305. The flow path switching device 300 is integrally assembled by screwing into the female thread portion 301A. When the check valve 303 is integrally assembled as the flow path switching device 300 as described above, the check valve 303 is pressed against the upper inner peripheral edge 319A of the tip of the valve bolt 305 by the biasing force of the spring 302. Closed state. The guide pin 304 has a predetermined play in the axial direction of the check valve 303 in the check valve 303 and in the internal space of the valve bolt 305.

5A and 5B are operation diagrams of the flow path switching device 300. FIG. Hereinafter, the operation of the flow path switching device 300 will be described with reference to FIG.
In the flow path switching device 300 accommodated in the flow path switching device accommodating hole 116, the distal end side enters the hydraulic oil guide tube 115, and the outer periphery of the valve case 301 is in close contact with the inner periphery of the hydraulic oil guide tube 115. At this time, in the hydraulic oil guide pipe 115, the top hole 301C of the valve case 301 opens on the intermediate chamber 149 side of the hydraulic oil guide pipe 115, and the through hole of the valve bolt 305 on the oil reservoir chamber 132 side of the hydraulic oil guide pipe 115. The hydraulic oil K flowing between the intermediate chamber 149 and the oil reservoir chamber 132 flows through the pressure suppression flow path S or the return flow path T inside the flow path switching device 300.

In the pressure side stroke and the extension side stroke, the case where the pressure of the intermediate chamber 149 is higher than the pressure of the oil reservoir chamber 132, that is, the case where the hydraulic oil K flows from the intermediate chamber 149 to the oil reservoir chamber 132 will be described.
As shown in FIG. 5 (a), the hydraulic oil K that has flowed out of the pressure side oil chamber 127A and the extension side oil chamber 127B by the operation of the piston 40 in the pressure side stroke and the extension side stroke is the compression side damping valve 151 and the extension side. The damping valve 161 is pushed open and flows into the intermediate chamber 149. The pressure in the intermediate chamber 149 increases until the pressure side check valve 152 and the extension side check valve 162 located downstream of the pressure side damping valve 151 and the extension side damping valve 161 in the compression side stroke and the extension side stroke are opened, and the oil reservoir A flow toward the chamber 132 occurs. Part of the hydraulic oil K from the intermediate chamber 149 toward the oil reservoir chamber 132 flows to the hydraulic oil guide tube 115 on the intermediate chamber 149 side and reaches the check valve mechanism of the flow path switching device 300.
The hydraulic oil K that has reached the check valve mechanism of the flow path switching device 300 flows into the flow path switching device 300 from the top hole 301C of the valve case 301, as indicated by an arrow u1 in the figure, so that the spring 302 is attached. The check valve 303 is pressed toward the valve bolt 305 together with the force. That is, the check valve is closed (the return channel T is closed), and only the pressure suppression channel S is opened. That is, the hydraulic oil K that has flowed from the hole 303C of the check valve 303 is a pressure formed by a gap between the inner peripheral surface 303a of the check valve 303 and the outer peripheral surface 304a of the guide pin 304, as indicated by an arrow u2 in the figure. It tries to flow in the direction of the oil reservoir chamber 132 of the temperature compensation means Q only through the suppression channel S. This pressure suppression channel S has a high inflow resistance because the opening of the inflow portion is set small as will be described later. For this reason, the pressure suppression flow path S cannot flow while maintaining the high pressure of the intermediate chamber 149, and only a small amount of hydraulic oil K can flow. Since the pressure of the oil reservoir chamber 132 is loaded from the outflow side of the pressure suppression channel S, the hydraulic oil K that can actually flow through the pressure suppression channel S is the oil reservoir chamber 132 and the hydraulic oil chamber. A portion that keeps the pressure of A and the intermediate chamber 149 constant flows. That is, the hydraulic oil K that has expanded due to the temperature rise of the hydraulic oil K on the side of the hydraulic oil chamber A or the intermediate chamber 149 has a pressure suppression flow as shown by an arrow u2 in the drawing in order to maintain a balance with the oil reservoir chamber 132. Thus, temperature compensation is performed to maintain a constant pressure in the hydraulic oil chamber A during the damping operation. In this way, the amount of operating hot water flowing into the oil reservoir chamber 132 is limited to a small amount with respect to the operating oil K, and temperature compensation is performed.
Due to the inflow amount limiting function of the pressure suppression passage S, the pressure generated by the operation of the piston 40 while absorbing the temperature expansion is almost maintained in the intermediate chamber 149. The check valve 162 is smoothly pushed and opened, and moves to the pressure side oil chamber 127A and the extension side oil chamber 127B located on the downstream side of the intermediate chamber 149 in the pressure side stroke and the extension side stroke.

On the other hand, when the pressure in the intermediate chamber 149 is lower than the pressure in the oil reservoir chamber 132 when the front fork 10 is not in operation other than the compression side stroke and the extension side stroke, that is, the hydraulic oil is supplied from the oil reservoir chamber 132 to the intermediate chamber 149. The case where K flows will be described.
As shown in FIG. 5B, when the front fork 10 does not operate in the compression stroke or extension stroke, that is, when the vehicle stops, the temperature of the hydraulic oil K of the damping force generator 140 is As a result, the volume of the hydraulic oil K contracts. In the hydraulic oil chamber A and the intermediate chamber 149, the pressure is reduced to a negative pressure state, while in the oil reservoir chamber 132, the positive pressure is always maintained by the pressurization of the free piston 133. When the pressure in the oil reservoir chamber 132 becomes higher than the pressure in the intermediate chamber 149 in this way, the check valve 303 of the flow path switching device 300 is pushed up due to the pressure difference between the oil reservoir chamber 132 and the intermediate chamber 149, and the seal The surface 303b is separated from the upper inner peripheral edge 319A, and at this time, the upper end surface of the guide pin 304 closes the hole 303C, so that the pressure suppression flow path S is closed, the return flow path T is opened, and the flow path The path S is switched to the return path T. That is, the switching of the flow path is performed by the hydraulic oil K in the oil reservoir chamber 132 flowing from the lateral hole 115 n to the seating cylinder 319 through the through hole 318 of the flow path switching device 300. That is, the hydraulic oil K that has flowed into the seating cylinder 319 as indicated by the arrow v1 in the figure causes the check valve 303 that has been pressed against the seating cylinder 319 by the biasing force of the spring 302 to the seating cylinder as indicated by the arrow v3 in the figure. The check valve 303 is pushed open through the gap between the inner periphery of 319 and the outer periphery of the guide pin 304, and flows on the outer periphery of the flange 303B as indicated by the arrow v4. With the flow of the hydraulic oil K indicated by arrows v3 and v4, the flow indicated by the arrow v2 in the figure is generated, the guide pin 304 is pressed toward the check valve 303, and the check valve 303 is maintained while the hole 303C is closed. The valve 303 is pushed to the top portion 301 </ b> B side of the valve case 301. As a result, the guide pin 304 closes the hole 303 </ b> C of the check valve 303 to close the pressure suppression passage S and the check valve 303 is opened, so that the hydraulic oil that communicates the oil reservoir 132 and the intermediate chamber 149. The flow path 115m is switched from the pressure suppression flow path S to the return flow path T from the oil reservoir chamber 132 toward the intermediate chamber 149.
By switching to the return flow path T with a large flow rate, the gap between the inner periphery of the seating cylinder 319 of the valve bolt 305 and the outer periphery of the guide pin 304 is changed from the oil reservoir chamber 132 to the intermediate chamber as indicated by an arrow v4 in the figure. 149 flows into the intermediate chamber 149 from the top hole 301C of the valve case 301 through the hydraulic oil flow path 115m, so that the pressure in the hydraulic oil chamber A and the intermediate chamber 149 is increased in the oil reservoir chamber 132. The same pressure as the pressure.
Therefore, when the front fork 10 is not operating (non-operating state), the pressure side oil chamber 127A and the extension side oil chamber 127B constituting the hydraulic oil chamber A, and the pressure side oil chamber 127A and the extension side oil chamber 127B are communicated. The pressures in the external flow path, the intermediate chamber 149, and the oil reservoir chamber 132 are constant.

FIGS. 6A and 6B are views showing the flow of the hydraulic oil K in the damping force generator 140 in the compression side stroke and the extension side stroke of the front fork 10. Hereinafter, the operation of the front fork 10 in the compression side stroke and the extension side stroke will be described with reference to FIG.
[Pressure side stroke]
In the pressure-side stroke in which the front fork 10 contracts, the hydraulic oil K in the pressure-side oil chamber 127A pressurized by the pressure-side operation of the piston 40 flows through the pressure-sharing shared flow in the damping force generator 140 via the pressure-side oil chamber flow path 57A. As shown by the solid line arrow f1 and the broken line arrow f4 in FIG. 6A, it is pushed out to the path 146A, and flows from the pressure expansion common flow path 146A toward the compression side damping force generator 250 and the bypass flow path 141A.
The hydraulic oil K that has flowed into the pressure-side damping force generator 250 flows from the gap provided in advance between the pressure-side flow regulating body 150 and the extension-side check valve 162 to the pressure-side flow path 150A side of the pressure-side flow regulating body 150. Then, the pressure side damping valve 151 is pushed open and flows out into the intermediate chamber 149.
The hydraulic oil K that has flowed into the bypass channel 141A from the tip of the valve piece 141 flows along the needle shaft 272 through the gap n1 formed by the needle hole 143B and the needle valve 272A, and mainly has a small diameter portion of the valve piece 141. As shown by the broken line arrow f5 from the channel hole 143A provided in the middle of 143 through the channel hole 145B of the center plate 145, it flows into the intermediate chamber 149 and merges with the hydraulic oil K via the pressure side channel 150A. The hydraulic oil K merged in the intermediate chamber 149 wraps around the outer periphery of the center plate 145 and flows into the hydraulic oil flow path 115m and the pressure side flow path 160B of the extension side flow regulating body 160 as indicated by solid line arrows f2 and f3 in the figure. .
With the function of the flow path switching device 300, the hydraulic oil K that has flowed into one hydraulic fluid flow path 115 m flows to the oil reservoir chamber 132 through the pressure suppression flow path S of the flow path switching device 300 only by the temperature expansion.
The hydraulic oil K that has flowed into the pressure side flow path 160B of the other extension side flow restriction body 160 is restricted in flow by the pressure suppression flow path S, and the amount pressurized by the piston 40 flows, so that the pressure side flow path 160B The pressure side check valve 152 is pushed open and flows out to the expansion side oil chamber 127B through the expansion pressure common flow path 146B and the expansion side oil chamber flow path 57B. The hydraulic oil K that has moved from the pressure-side oil chamber 127A to the expansion-side oil chamber 127B in this pressure-side stroke becomes substantially equal to the volume of the movement of the piston 40, and the pressure-side stroke is attenuated without a response delay accompanying the movement of the piston 40. Power is obtained.

[Stretching process]
In the extension side stroke in which the front fork 10 extends, the hydraulic oil K in the extension side oil chamber 127B pressurized by the extension side operation of the piston 40 is extended by the damping force generator 140 through the extension side oil chamber channel 57B. As shown by the solid line arrow g1 and the broken line arrow g4 in FIG. 6B, the pressure is shared by the pressure common flow path 146B and flows from the pressure common flow path 146B toward the extension side damping force generation unit 260 and the bypass flow path 141A. .
The hydraulic oil K that has flowed from the pressure expansion common flow path 146B to the expansion side damping force generation unit 260 extends from the gap provided in advance between the expansion side flow path 160A of the expansion side flow regulating body 160 and the pressure side check valve 152. It flows into the flow path 160 </ b> A, pushes open the expansion side damping valve 161, and flows out into the intermediate chamber 149.
Further, the hydraulic oil K that has flowed into the bypass flow path 141A from the large diameter portion 142 side through the flow passage hole 142A of the large diameter portion 142 of the valve piece 141 from the pressure expansion common flow path 146B is a tapered surface of the flow rate adjusting body 279. It flows along the needle shaft 272 through a gap n2 between 279B and the opening 144B on the inner peripheral side of the small diameter portion 143. The hydraulic oil K that has flowed along the needle shaft 272 through the gap n2 mainly passes through the flow path hole 143A provided in the middle of the valve piece 141 through the flow path hole 145B of the center plate 145, as indicated by a broken line arrow g5. It flows into the intermediate chamber 149 and merges with the hydraulic oil K that passes through the expansion side flow path 160A of the expansion side damping force generation unit 260. The hydraulic oil K merged in the intermediate chamber 149 wraps around the center plate 145 and enters the hydraulic oil flow path 115m and the expansion side flow path 150B of the pressure side flow regulating body 150 as indicated by solid line arrows g2 and g3 in the figure. Flowing.
As for the hydraulic oil K that has flowed into one hydraulic oil flow path 115 m, due to the function of the flow path switching device 300, only the hydraulic oil K for the temperature expansion is transferred to the oil reservoir chamber 132 through the pressure suppression flow path S of the flow path switching device 300. Flowing.
The hydraulic oil K that has flowed into the pressure side flow path 160B of the other extension side flow restriction body 160 is restricted in flow by the pressure suppression flow path S, and the amount pressurized by the piston 40 flows, so that the pressure side flow path 160B The pressure side check valve 152 is pushed open and flows out to the expansion side oil chamber 127B through the expansion pressure common flow path 146B and the expansion side oil chamber flow path 57B. The hydraulic oil K that has moved from the expansion side oil chamber 127B to the compression side oil chamber 127A in this expansion side stroke is substantially equal to the volume of the movement of the piston 40.

  As described above, the hydraulic oil K is allowed to flow from the intermediate chamber 149 to the oil reservoir chamber 132, and the pressure generated in the intermediate chamber 149 by the operation of the piston 40 is not transmitted to the oil reservoir chamber 132. By providing the pressure suppression passage S that suppresses the pressure of the hydraulic oil K flowing through the hydraulic oil guide pipe 115 of the hydraulic oil K, the hydraulic oil K corresponding to the temperature expansion of the hydraulic oil K in the hydraulic oil chamber A and the intermediate chamber 149 Since only the flow from the intermediate chamber 149 to the oil reservoir chamber 132 flows through the pressure suppression flow path S, the operation of the piston 40 causes the compression side oil chamber 127A to the extension side oil chamber 127B, or the extension side oil chamber 127B to the pressure side oil chamber 127A. Since the hydraulic oil K to be moved moves without delay, a damping force is generated without causing a response delay in the compression side stroke and the extension side stroke, so that the responsiveness during the damping operation can be improved. That.

In the above-described embodiment, the hydraulic shock absorber according to the present invention has been described using the front fork 10, but the present invention is not limited to the front fork 10 and may be used for a rear cushion of a motorcycle.
Further, the pressure suppression channel S has been described as being closed when the return channel T is opened, but may remain open.
Further, the hydraulic oil flow passage 115m that connects the intermediate chamber 149 and the oil reservoir chamber 132 is described as being connected by the hydraulic oil guide tube 115, but the intermediate chamber 149 and the oil reservoir chamber 132 communicate with each other in the axle holder 50. You may form as a hole.

10 front fork, 11 outer tube, 15 piston rod,
40 piston, 51 cylinder tube, 52 guide tube,
60 partition members, 115 hydraulic oil guide tube, 115 m hydraulic oil flow path, 115 n lateral hole,
116 channel switching device accommodation hole,
127A compression side oil chamber, 127B extension side oil chamber,
140 damping force generator, 250 compression side damping force generator, 260 extension side damping force generator,
300 channel switching device, 303 check valve, S pressure suppression channel, T return channel,
Q Temperature compensation means, Z hydraulic fluid flow control means.

Claims (7)

Body side tube,
An axle side tube that is slidably fitted to the vehicle body side tube; and
A cylindrical cylinder tube erected from the bottom of the axle side tube;
A partition member provided in the cylinder tube, in close contact with the inner periphery of the axle-side tube in a liquid-tight state, and partitioning the vehicle body side of the inner space of the axle-side tube so as to serve as an air chamber and the axle side as a hydraulic oil chamber; ,
In the sliding movement of the vehicle body side tube and the axle side tube, it is provided so as to be movable together with the vehicle body side tube. Inside the cylinder tube, the vehicle body side of the hydraulic oil chamber is an extension side oil chamber, and the axle side is a pressure side oil chamber. A partitioning piston;
A rod attached to the piston and provided movably in and out of the cylinder tube along the axial direction of the cylinder tube;
A cylindrical guide tube that stands upright from the bottom of the axle-side tube so that the inner peripheral side communicates with the outside air, and that guides the outer periphery of the rod extending from the piston toward the bottom of the axle-side tube in a liquid-tight state. When,
A flow hole communicating with the space formed between the inner periphery of the axle side tube and the outer periphery of the cylinder tube and the extension side oil chamber and allowing mutual flow of hydraulic oil;
A fluid passage between oil chambers that enables the flow of hydraulic oil between the pressure side oil chamber and the extension side oil chamber;
A compression-side damping force generation unit and an extension-side damping force generation unit that are provided outside the hydraulic oil chamber and generate a damping force by generating resistance in the hydraulic oil flowing through the flow path between the oil chambers are arranged in series along the flow direction. A damping force generator provided in
Temperature compensation means having a pressure adjusting oil reservoir that absorbs temperature expansion generated in the hydraulic oil by allowing a part of the hydraulic oil to flow in and out between the compression-side damping force generator and the extension-side damping force generator. A hydraulic shock absorber comprising:
Based on the pressure of the hydraulic oil flowing in the direction of the pressure adjusting oil reservoir in the pressure side stroke and the extension side stroke in the operation of the hydraulic shock absorber, the flow rate of the hydraulic oil flowing in the direction of the pressure adjusting oil reservoir chamber is changed to the pressure side stroke. The hydraulic shock absorber further comprises hydraulic fluid flow rate control means for limiting the amount to a smaller amount than when the hydraulic fluid flows out when the piston other than the extension stroke is not operating. The hydraulic oil flow rate control means includes a return flow path communicating between the damping force generator side and the pressure adjusting oil reservoir chamber;
A pressure suppression channel having a smaller opening than the return channel;
2. The hydraulic shock absorber according to claim 1, wherein the hydraulic shock absorber is configured by a flow path switching device having a check valve mechanism that opens the pressure suppression flow path and closes the return flow path.   3. The hydraulic shock absorber according to claim 2, wherein the return flow path is opened by a hydraulic oil outflow pressure from the pressure adjusting oil reservoir chamber when the piston is not operating. 4.   4. The hydraulic shock absorber according to claim 3, wherein the pressure suppression channel is closed when the return channel is opened. The damping force generator is
Between the compression side damping force generation part and the extension side damping force generation part,
There is an intermediate chamber through which the hydraulic oil flowing from the pressure side oil chamber flow path side to the expansion side oil chamber flow path direction in the compression side stroke and the hydraulic oil flowing from the expansion side oil chamber flow path side to the pressure side oil chamber flow path direction in the expansion side stroke pass. And
The hydraulic shock absorber according to claim 2 or 3, wherein one end of the return flow path and the pressure suppression flow path communicates with the intermediate chamber side.   The amount of opening of the pressure suppression channel that is opened and closed by the check valve mechanism is such that the hydraulic oil that has expanded due to a rise in the temperature of the hydraulic oil in the damping force generator is from the intermediate chamber side to the pressure adjusting oil reservoir chamber. The hydraulic shock absorber according to claim 5, wherein the hydraulic shock absorber is set to an opening amount that allows the flow in the direction. The pressure adjusting oil reservoir chamber of the temperature compensation means is connected to an intermediate chamber through a hydraulic oil guide pipe, and a check valve mechanism is provided in the hydraulic oil flow path of the guide pipe. The hydraulic shock absorber according to claim 5 or claim 6.

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