JPH0425548Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field This invention relates to a variable damping force hydraulic shock absorber.

BACKGROUND TECHNOLOGY Among variable damping force hydraulic shock absorbers used in automobile suspensions, for example, there are
As shown in Japanese Patent Application Laid-open No. 109929 and Japanese Patent Application Laid-open No. 60-227031, there are known devices in which the damping force during the extension stroke and the compression stroke can be adjusted separately.

The damping force variable hydraulic shock absorber disclosed in the above-mentioned Japanese Utility Model Application Publication No. 61-109929 is designed as shown in FIG. That is, as shown in FIG. 6A, the piston 1 is inside the cylinder 101 of this variable damping force hydraulic shock absorber
02, the upper liquid chamber 10 is filled with hydraulic fluid.
3 and a lower liquid chamber 104 are defined. The piston 102 is supplied with hydraulic fluid during the extension stroke through the upper fluid chamber 10.
a damping force generating mechanism 105 that displaces the working fluid from the lower fluid chamber 104 to the lower fluid chamber 104; and a damping force generating mechanism 10 that displaces and circulates the working fluid from the lower fluid chamber to the upper fluid chamber during the pressure stroke.
6 is provided. The piston rod 107 to which the piston 102 is fixed has an upper liquid chamber 10 that bypasses the damping force generating mechanisms 105 and 106.
3 and the lower liquid chamber 104.
08 is formed. This bypass passage 108
Inside, an adjuster 110 of the variable damping force mechanism 109 is arranged so as to be rotatable in the circumferential direction. This regulator 110 has a plurality of extension side orifices 111 of different diameters for adjusting the amount of bypass of the working fluid, and a plurality of compression side orifices 112 of different diameters for adjusting the amount of bypass of the working fluid, formed in upper and lower stages. has been done.
The piston rod 107 has a growth side through hole 113 (sixth
(see Figure B), and a plurality of pressure side orifices 11
Pressure side through hole 1 selectively communicated with one of 2.
14 are formed. piston rod 107
An annular groove 115,
116 is formed. piston rod 107
A holder 117 that covers the annular grooves 115 and 116 is fitted and fixed on the outer peripheral surface of the holder 117 . A growth side through hole 118 and a compression side through hole 119 are formed in portions of the holder 117 corresponding to the annular grooves 115 and 116, respectively. The inner peripheral surface of this holder 117 and the annular groove 1
An expansion side check valve 122 and a compression side check valve 123 are provided in each of the expansion side valve chamber 120 and the compression side valve chamber 121, which are formed by the expansion side valve chamber 15 and 116. Extension side check valve 122
As shown in FIG.
07, and its outer circumferential surface is in contact with the inner circumferential surface of the holder 117, while the expansion side through hole 11 of the holder 117
8 is closed, and the upper liquid chamber 10 during the extension stroke.
3, it opens in the inner radial direction centering on the support point with the piston rod 107. Due to this valve opening operation of the expansion side check valve 122, a part of the working fluid in the upper liquid chamber 103 is transferred from the expansion side through hole 118 of the holder 117 to the expansion side valve chamber 120 to the expansion side through hole 113 of the piston rod 107. →By the rotation of the adjuster 110, the expansion side through hole 113 of the piston rod 107 is
Extension side orifice 111 that selectively communicates with →
Passing through the bypass passage 108 in order, the lower liquid chamber 104
It is now being distributed as a replacement. Further, as shown in FIG. 6B, the pressure side check valve 123 is formed into a substantially semi-circular plate shape, one end of which is fixed to the piston rod 107, and the inner circumferential surface of which is connected to the annular groove 116 of the piston rod 107. While contacting the bottom surface of the groove, the pressure side through hole 114 of the piston rod 107 is closed, and as the pressure of the lower liquid chamber 104 increases during the pressure stroke, it opens in the outer radial direction around the support point with the piston rod 107.
Due to this valve opening operation of the pressure side check valve 123, a part of the working fluid in the lower liquid chamber 104 is selectively communicated with the pressure side through hole 114 of the piston rod 107 through the rotation of the bypass passage 108→adjuster 110. The liquid is exchanged into the upper liquid chamber 103 through the pressure side orifice 112, the pressure side through hole 114 of the piston rod 107, the pressure side valve chamber 121, and the pressure side through hole 119 of the holder 117 in this order.

The variable damping force type hydraulic shock absorber disclosed in Japanese Patent Application Laid-Open No. 60-227031 is designed as shown in FIG. In other words, cylinder 2 of this variable damping force type hydraulic shock absorber
01, an upper liquid chamber 203 and a lower liquid chamber 204 filled with hydraulic fluid are defined by a piston 202. The piston 202 includes a damping force generating mechanism 205 that displaces hydraulic fluid from the upper fluid chamber 203 to the lower fluid chamber 204 during the extension stroke, and a damping force generating mechanism 205 that displaces and circulates the hydraulic fluid from the lower fluid chamber 204 to the upper fluid chamber 203 during the compression stroke.
A damping force generating mechanism 206 is provided which allows the damping force to be replaced and circulated. The piston rod 207 to which the piston 202 is fixed has a damping force generating mechanism 20.
An adjuster 209 of the variable damping force mechanism 208 is disposed to be rotatable in the circumferential direction, bypassing the damping force variable mechanism 208 and displacing the hydraulic fluid into the upper liquid chamber 203 and the lower liquid chamber 204 by bypassing the hydraulic fluid. This regulator 209 has a plurality of extension side orifices 210 of different diameters for adjusting the bypass amount of the hydraulic fluid, and a plurality of compression side orifices 211 of different diameters for adjusting the bypass amount of the hydraulic fluid, which are formed in two stages, upper and lower. has been done. The piston rod 202 has a growth-side through hole 212 that selectively communicates with one of the plurality of growth-side orifices 201 and one of the plurality of compression-side orifices 211 through the rotation of the adjuster 209 . A pressure side through hole 213 is formed which communicates with the pressure side through hole 213. An extension check valve 214 is provided at the lower end of the piston rod 207. The extension side check valve 214 opens downward against the elastic force of the spring 215 due to the pressure increase in the upper liquid chamber 203 during the extension stroke. This expansion side check valve 21
4, a part of the hydraulic fluid in the lower fluid chamber 203 flows through the upper through hole 216 of the piston 202→
Oil passage 217 of piston 202 → piston rod 2
07 through the expansion side through hole 212 → the expansion side orifice 210 that selectively communicates with the expansion side through hole 212 of the piston rod 207 by rotation of the adjuster 209 → the expansion side oil passage 218 of the piston rod 207 in this order. The liquid is exchanged and distributed to the lower liquid chamber 204. Also, the piston 2 of the piston rod 207
A pressure side check valve 219 is provided on the outer periphery above 02. This pressure side check valve 219 opens upward against the elastic force of the spring 220 due to the pressure increase in the lower liquid chamber 204 during the pressure stroke. This pressure side check valve 21
9, a part of the hydraulic fluid in the lower liquid chamber 204 flows through the lower through hole 221 of the piston 202→
Oil passage 222 of piston 202 → piston rod 2
07 through the expansion side through hole 213 → the expansion side orifice 211 which selectively communicates with the expansion side through hole 213 of the piston rod 207 by rotation of the adjuster 209 → the upper liquid chamber through the upper compression side oil passage 223 in this order. 203 has been replaced and distributed.

Problems to be Solved by the Invention In the variable damping force type hydraulic shock absorber shown in FIG.
71 is fitted externally, and the inner circumferential surface of this holder 117 and the annular grooves 115, 116 of the piston rod 107 form a growth side valve chamber 120 and a pressure side valve chamber 121 in two stages, upper and lower. Inner and pressure side valve chamber 1
Since the expansion side check valve 122 and the compression side check valve 123 are individually arranged in each of the piston rods 21, a stopper (a meshed member provided on the holder 117 in FIG. 6) that regulates the stroke of the piston rod is provided. Since the piston rod 107 is provided above the holder 117, the stroke of the piston rod 107 becomes shorter, and the overall length of the variable damping force type hydraulic shock absorber becomes longer. Moreover, if there is an error in the radius of curvature between the expansion side check valve 122 and the inner circumferential surface of the holder 117, or if there is an error in the radius of curvature between the compression side check valve 123 and the groove bottom surface of the annular groove 116, the check valve Since the sealing performance as
3 and the groove bottom surface of the annular groove 116 requires a great deal of effort and time, and there is a limit to how much cost can be reduced.

Even in the variable damping force type hydraulic shock absorber shown in FIG. 7, since the pressure side check valve 219 is provided on the outer periphery of the piston rod 207, the stopper that regulates the stroke of the piston rod is placed above the compression side check valve 219. This has the disadvantage that the stroke of the piston rod 207 becomes shorter and the overall length of the variable damping force type hydraulic shock absorber similar to the above becomes longer.

Means for Solving the Problems In order to solve these problems, this invention defines an upper liquid chamber and a lower liquid chamber filled with hydraulic fluid by means of a piston in a cylinder. The piston is provided with a damping force generating mechanism that exchanges and circulates working fluid between an upper fluid chamber and a lower fluid chamber during an extension stroke and a compression stroke, and a bypass passage communicating with the lower fluid chamber is provided in the piston rod to which the piston is fixed. The piston rod of the circumferential wall of the bypass passage is formed with an extension side through hole and a compression side through hole that communicate the bypass passage with the upper liquid chamber in two stages, upper and lower, and a plurality of expansion side orifices of different diameters are formed in the bypass passage. A regulator in which a plurality of compression side orifices of different diameters are formed in upper and lower two stages is rotatably arranged, and by rotation of this regulator, one of the plurality of extension side orifices is connected to the extension side through hole. By selectively communicating with the compression side orifice and selectively communicating with the compression side orifice, the damping force generating mechanism is bypassed during the extension stroke and the compression stroke, and the upper liquid is While configuring a damping force variable mechanism in which the bypass amount of the working fluid exchanged between the chamber and the lower fluid chamber can be adjusted individually,
An expansion side valve chamber that communicates with the expansion side orifice and a compression side valve chamber that communicates with the compression side orifice are defined inside the regulator by a partition wall, and the expansion side valve chamber has an expansion side valve chamber that opens in the axial direction during the compression stroke. A check valve is provided in the pressure side valve chamber, and the pressure side check valve opens in the axial direction during the pressure stroke.

Operation: By rotating the adjuster, one of the plurality of extension side orifices with different diameters is selectively communicated with the extension side through hole of the piston rod, and one of the plurality of compression side orifices with different diameters is selectively communicated with the extension side through hole of the piston rod. By selectively communicating with the compression side through hole of the piston rod, the damping force during the extension stroke and the compression stroke can be adjusted separately.

Moreover, by providing the rebound check valve and the compression check valve inside the regulator, the members necessary for storing and operating the rebound check valve and the compression check valve do not protrude outside the piston rod. This makes it possible to provide a stopper that regulates the stroke of the piston rod below the piston rod's expansion side through hole and compression side through hole, which lengthens the stroke of the piston rod and shortens the overall length of the variable damping force type hydraulic shock absorber. Become.

In addition, since the expansion side check valve and the compression side check valve are configured to open in the axial direction, the expansion side check valve is in flat contact with the expansion side valve seat portion, and the compression side check valve is in flat contact with the compression side valve seat portion. It is possible to adopt a simple valve mechanism that makes contact with the

Embodiments Hereinafter, embodiments of this invention will be described in detail based on the drawings.

FIG. 1 shows a variable damping force type hydraulic shock absorber according to a first embodiment. In the cylinder 1 of the variable damping force type hydraulic shock absorber shown in FIG. 1, an upper liquid chamber 3 and a lower liquid chamber 4 are defined by a piston 2. The piston 2 is provided with a damping force generating mechanism 5. The damping force generating mechanism 5 includes a plurality of passages 6 that are spaced apart in the circumferential direction of the piston 2 and penetrate in the vertical direction, and a plurality of passages 6 that are provided on the upper surface of the piston 2 and that connect at least one of the plurality of passages 6 to the upper surface of the piston 2. An upper slit 7 communicating with the liquid chamber 3 and a piston 2
a lower surface slit 8 provided on the lower surface to communicate at least one other of the plurality of passages 6 to the lower liquid chamber 4; and an extension side valve body arranged on the lower surface of the piston 2 to cover the plurality of passages 6. 9 and a pressure-side valve body 10 disposed on the upper surface of the piston 2 and covering the plurality of passages 6, the pressure side valve body 10 is arranged on the upper surface of the piston 2 and covers the plurality of passages 6. When this happens, the expansion side valve body 9 opens, and a part of the hydraulic fluid in the upper liquid chamber 3 passes through the upper slit 7 and the passage 6 in order, as shown by the arrow X, and is replaced and distributed to the lower liquid chamber 4. However, when the pressure in the lower liquid chamber 4 due to the downward movement of the piston 2 during the pressure stroke exceeds a predetermined value, the pressure side valve body 10 opens, and a part of the working liquid in the lower liquid chamber 4 is released as indicated by the arrow X ₂ As shown in , a fixed damping force is generated by passing through the lower slit 8 and the passage 6 in order and displacing the liquid into the upper liquid chamber 3. The piston 2 is fastened with a nut 15 to a stud 14 coaxially screwed into the lower end of the rod body 13 of the piston rod 12. A bypass passage 16 is formed extending from the axial center of the lower end surface of the stud 14 to the lower part of the rod body 13, bypassing the damping force generating mechanism 5 and communicating with the lower liquid chamber 4. Rod body 1 of this bypass passage 16
3, a covered cylindrical adjuster 18 of the variable damping force mechanism 17 is arranged so as to be rotatable in the circumferential direction with cylindrical bushes 19 and 20 interposed above and below. At the top of this adjuster 18, there is a rod body 13.
The lower ends of a control rod 22 which passes through the shaft center of the bush 19 and is driven by an actuator (not shown) are coupled to each other. On the circumferential wall of the regulator 18, there are a plurality of extension orifices 23 of different diameters for adjusting the amount of bypass of the working fluid, and a plurality of pressure side orifices 24 of different diameters for adjusting the amount of bypass of the working fluid, arranged in upper and lower stages. It is formed. The circumferential wall of the piston rod 12 located outside the adjuster 18 is selectively communicated with one of the plurality of expansion-side orifices 23 by rotationally driving the adjuster 18 via the control rod 22 by the actuator. A compression side through hole 25 that is selectively communicated with one of the plurality of compression side orifices 24 is formed. Inside the regulator 18, a growth side valve chamber 28 communicating with the growth side orifice 23 and a pressure side valve chamber 29 communicating with the compression side orifice 24 are defined by a partition wall 27. In the expansion side valve chamber 28, a growth side check valve 31 that opens axially downward is provided, and in this pressure side valve chamber 29, a compression side check valve 32 that opens axially upward is provided.

Specifically, the expansion side check valve 31 and the compression side check valve 32 are as shown in FIG. In other words, the expansion side check valve 31
The diameter of the expansion side valve chamber 28 and the diameter of the expansion side valve chamber 28 extend downward from the valve body 33 via an inclined step 34. A cylindrical skirt portion 3 that is connected to each other with approximately the same diameter and is slidable in the vertical direction on the circumferential surface of the expansion side valve chamber 28
5. A caulking portion 36 of the control rod 22 is attached to the axial center of the ceiling of the valve body portion 33.
A through hole 37 having a slightly larger diameter is formed.
The upper surface of the ceiling of the valve body part 32 is moved between the expansion side valve chamber 2 and
It is seated on an extension side valve seat portion 39 which is formed to bulge downward from the top surface of the valve 8 . This valve body part 32
The growth side check valve 31 is closed by the seated state on the growth side valve seat portion 39. During the extension stroke, the pressure in the upper liquid chamber 3 is transferred from the expansion side through hole 25 of the piston rod 12 to the expansion side through hole 25 of the piston rod 12, which is selectively communicated with the expansion side through hole 25 of the piston rod 12 by the rotation of the adjuster 18. Through the side orifice 23, the skirt portion 35 of the expansion side check valve 31 acts downwardly on the inclined step portion 34 of the expansion side check valve 31 exposed in the expansion side valve chamber 28.
slides on the circumferential surface of the expansion side valve chamber 28, the expansion side check valve 31 moves downward against the elastic force of the expansion side check spring 38, and the valve body portion 33 of the expansion side check valve 31 moves toward the expansion side. Moving away from the valve seat portion 38, the expansion side check valve 31 opens, and a portion of the hydraulic fluid in the upper fluid chamber 3 flows through the expansion side through hole 25 of the piston rod 12 → adjustment, as shown by arrow _X3 in FIG. Selected expansion side orifice 23 of child 18 → expansion side check valve 31 that was opened → expansion side check valve 31
through hole 37 → through hole 41 of partition wall 27 → center hole 49 of sheet member 46 → center hole 50 of bush 20
→By passing through the bypass passage 16 of the stud 14 and circulating to the lower liquid chamber 4, the regulator
A variable damping force is generated according to the amount of bypass corresponding to the expansion side orifice 23 selected in step 8.

Further, the pressure side check valve 32 is slidable in the vertical direction on a support portion 42 formed in a cylindrical shape bulging downward from the periphery of a vertical through hole 41 formed in the axial center of the partition wall 27. It includes an externally fitted cylindrical guide part 43 and a closed annular valve body part 44 which is bent outward from the lower edge of this guide part 43 to have a diameter smaller than the diameter of the pressure side valve chamber 29. ing. The lower surface of this valve body part 44 is connected to a cylindrical seat connected to the lower part of the regulator 18 by the elastic force of a compression side check spring 45 disposed astride the upper surface of the valve body part 44 and the partition wall 27. It is seated on an extension side valve seat portion 47 formed on the upper outer side of the member 46 and located near the compression side orifice 24 . With the valve body portion 44 seated on the pressure side valve seat portion 47, the pressure side check valve 32 is closed. Inside the pressure side valve seat portion 47 of this seat member 46, there are a plurality of longitudinal grooves 4 spaced apart in the circumferential direction.
8 is formed. The plurality of vertical grooves 48 include
A corner of the pressure side check valve 32 where the valve body portion 44 and the guide portion 43 are connected is exposed. During the pressure stroke, the pressure within the lower liquid chamber 4 of the piston 2 is
From the bypass passage 16 of the stud 14, through the center hole 20 of the bush 20, to the longitudinal groove 4 of the seat member 46.
8 and acts upwardly on the valve body portion 44 of the compression side check valve 32 exposed in the vertical groove 48, while the guide portion 43 of the compression side check valve 32 slides on the support portion 42, the pressure side check valve 32 is moved upwardly. valve 32
moves upward against the elastic force of the pressure side check spring 45, the valve body portion 44 of the pressure side check valve 32 separates from the pressure side valve seat portion 47, the pressure side check valve 32 opens, and the hydraulic fluid in the lower fluid chamber 4 is released. Some of the
As shown by arrow _X4 in FIG. 1, the bypass passage 16 of the stud 14 → the center hole 50 of the bush 20
The pressure side check valve 32 that has been opened → the pressure side valve chamber 28 → the pressure side orifice 24 that selectively communicates with the pressure side through hole 26 of the piston rod 12 by the rotation of the regulator 18 → the pressure side through hole 26 of the piston rod 12 in this order. A variable damping force is generated according to the amount of bypass corresponding to the pressure side orifice 24 selected by the regulator 18 by displacing the liquid through the lower liquid chamber 4 .

Therefore, in this first embodiment, the regulator 18
, one of the plurality of extension-side orifices 23 having different diameters is selectively communicated with the extension-side through hole 25 of the piston rod 12, and one of the plurality of compression-side orifices 24 having different diameters By selectively communicating with the compression side through hole 26 of the piston rod 12, the fixed damping force of the damping force generating mechanism 5 and the individual damping force of the variable damping force generating mechanism 17 are generated during the extension stroke and the compression stroke. By summing the variable damping force depending on the amount of bypass, each variable damping force mode, for example, soft, medium, and hard, can be individually set.

Moreover, according to this first embodiment, the adjuster 18
The expansion side valve chamber 28 which communicates with the expansion side orifice 23 of the regulator 18 and the pressure side valve chamber 29 which communicates with the compression side orifice 24 of the regulator 18 are defined inside by the partition wall 27, and the expansion side valve chamber 28 Since the expansion side check valve 31 is provided inside the engine and the compression side check valve 32 is installed inside the compression side valve chamber 29, the expansion side check valve 31 is installed within the compression side valve chamber 29.
The members necessary for housing and operation of the piston rod 12 and the pressure side check valve 32 do not protrude outside the piston rod 12. Therefore, it is possible to provide a stopper (not shown) for regulating the stroke of the piston rod 12 on the shoulder of the stud 14 located below the compression side through hole 26. Moreover, since the outer diameter of the portion of the piston rod 12 where the expansion side through hole 25 and the compression side through hole 26 are provided is narrow, even if the stopper comes into contact with a rod guide (not shown), the expansion side through hole 25 This means that the pressure side through hole 26 is in communication with the upper liquid chamber 3 without being blocked by the rod guide. Therefore, the stroke of the piston rod 12 becomes longer, and the overall length of the variable damping force type hydraulic shock absorber becomes shorter. Further, since the expansion side check valve 31 and the compression side check valve 32 are configured to open in the axial direction, the expansion side check valve 31 contacts the expansion side valve seat portion 38 in a plane, and the compression side check valve 32 It is possible to adopt a normal valve mechanism that contacts the pressure side valve seat portion 47 in a plane, and therefore, it is possible to adopt a conventional valve mechanism that contacts the pressure side valve seat portion 47 in a plane, and therefore, it is possible to use a complicated valve mechanism that matches the radius of curvature of the valve body and the valve seat, as in the conventional example shown in FIG. Cost reduction can be achieved without using a valve mechanism.

FIG. 3 shows a variable damping force type hydraulic shock absorber according to a second embodiment. The variable damping force type hydraulic shock absorber shown in FIG. 3 is characterized in that the growth side valve seat portion 39A is disposed below the growth side check valve 31A. Specifically, as shown in FIG.
A cylindrical skirt portion 35A that has approximately the same diameter as the expansion-side valve chamber 28 defined by the expansion-side valve chamber 28 and can slide vertically on the circumferential surface of the expansion-side valve chamber 28; A disc-shaped valve body portion 33A is formed. A through hole 52 is formed in the axial center of the valve body portion 33A. The lower surface of the valve body portion 33A is controlled by the elastic force of the expansion side check spring 38A, which is disposed across the upper surface of the valve body portion 33A and the top surface in which the through hole 53 of the expansion side valve chamber 28 is formed. It is seated on an extension side valve seat portion 39A that is formed to bulge upward from the partition wall 27 into a cylindrical shape.
Further, the lower part of the support part 42 bulging downward from the partition wall 27 into a cylindrical shape is fitted into the upper part of the center hole 49 of the cylindrical sheet member 46 connected to the adjuster 18, and this support Sheet member 4 of member 42
A vertical hole 55 is formed in the fitting portion with 6, which communicates the center hole 49 with an annular recess 54 formed inside the pressure side valve seat portion 47A. Furthermore, an expansion side orifice 23 and a compression side orifice 24 are formed on the peripheral wall of the regulator 18 so as to approach the partition wall 27. In addition, in FIG. 3 of this second embodiment, it is possible to set the shoulder of the stud 14 lower than the illustrated position and provide a stopper for regulating the stroke of the piston rod 12 at this shoulder.

Therefore, according to the second embodiment, since the vertical distance between the expansion side orifice 23 and the compression side orifice 24 is set to the minimum dimension L shown in FIG.
The vertical separation between the compression side through hole 25, which communicates in the radial direction of the piston rod 12, and the compression side through hole 26, which communicates with the compression side orifice 24 in the radial direction of the piston rod 12, is also minimized, so the stroke of the piston rod is maximized, and damping is achieved. The overall length of the variable force hydraulic shock absorber can be significantly shortened.

FIG. 5 shows a regulator 18 as a third embodiment. In the adjuster 18 shown in FIG. 5, the vertical distance between the expansion side orifice 23 and the compression side orifice 24 is formed on the peripheral wall of the adjuster 18 to be the same as the minimum dimension L shown in FIG. , the extension side check valve 31B is formed in substantially the same shape as the extension side check valve 31 shown in FIG. 2, and the length of the skirt portion 35B of this extension side check valve 31B is
It is formed to have a shorter dimension than the skirt portion 35 of the expansion side check valve 31 shown in FIG.
By using the one shown in FIG. 4 for 6A, it is possible to obtain the same effects as in the second embodiment.

Effects of the invention As described above, according to this invention, in a variable damping force hydraulic shock absorber in which the damping force during the extension stroke and the compression stroke are individually adjusted, an extension side orifice is installed in the piston rod. A damping force variable mechanism adjuster is rotatably arranged in which the compression side orifice is formed in two stages, upper and lower, and inside this adjuster, the compression side valve chamber and the compression side orifice are connected to the expansion side valve chamber which communicates with the expansion side orifice through a partition wall. The compression side valve chamber communicates with the compression side valve chamber, and the expansion side check valve and the compression side check valve that open in the axial direction are individually provided in the expansion side valve chamber and the compression side valve chamber, respectively, so that the expansion side check valve and the compression side check valve The members necessary for storing and operating the valve do not protrude outside the piston rod, and therefore, the stopper for regulating the stroke of the piston rod is provided below the expansion side through hole and the compression side through hole of the piston rod. This makes it possible to lengthen the stroke of the piston rod and shorten the overall length of the variable damping force type hydraulic shock absorber.

Further, according to this invention, the expansion side check valve and the compression side check valve are configured to open in the axial direction, so that the expansion side check valve contacts the expansion side valve seat portion in a flat manner, and the compression side check valve Since it is possible to use a normal valve mechanism that makes two-dimensional contact with the pressure side valve seat, there is no need to use a complicated valve mechanism that matches the radius of curvature of the valve body and valve seat as in conventional examples, reducing costs. can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view showing a variable damping force type hydraulic shock absorber according to the first embodiment of this invention, FIG. 2
FIG. 4 is a longitudinal sectional view showing a variable damping force type hydraulic shock absorber according to an embodiment, FIG. 4 is a longitudinal sectional view showing an adjuster according to a second embodiment, and FIG. 5 is a longitudinal sectional view showing an adjuster according to a third embodiment of this invention. The sectional view and FIG. 6 show a conventional variable damping force type hydraulic shock absorber, where A is the overall longitudinal sectional view and B is the cross-sectional view.
7 is a sectional view taken along the line BB of A, C is a sectional view taken along the line C-C of A, and FIG. 7 is a longitudinal sectional view showing a different conventional variable damping force type hydraulic shock absorber. 1... Cylinder, 2... Piston, 3... Upper hydraulic pressure, 4... Lower liquid chamber, 5... Damping force generation mechanism,
12... Piston rod, 16... Bypass passage, 17... Damping force variable mechanism, 18... Adjuster,
23... Growth side orifice, 24... Compression side orifice, 25... Growth side through hole, 26... Compression side through hole, 27
. . . Partition wall, 28 . . . Growth side valve chamber, 29 .

Claims (1)

[Scope of utility model registration request] A piston defines an upper liquid chamber and a lower liquid chamber filled with hydraulic fluid in the cylinder, and the piston supplies hydraulic fluid to the upper liquid chamber and the lower liquid chamber during an extension stroke and a pressure stroke. A damping force generation mechanism for displacing the fluid is provided, a bypass passage communicating with the lower liquid chamber is formed in the piston rod to which the piston is fixed, and an extension side through hole is provided in the piston rod on the circumferential wall of the bypass passage, communicating the bypass passage with the upper liquid chamber. and compression side through holes are formed in upper and lower two stages, and a plurality of extension side orifices with different diameters and a plurality of compression side orifices with different diameters are formed in upper and lower two stages in the bypass passage, and a regulator is rotatably arranged. By rotating this adjuster,
By selectively communicating one of the plurality of extension side orifices with the extension side through hole and selectively communicating one of the plurality of compression side orifices with the compression side through hole, during the extension process. The damping force variable mechanism constitutes a damping force variable mechanism in which the bypass amount of the hydraulic fluid that bypasses the damping force generation mechanism and is exchanged and circulated to the upper liquid chamber and the lower liquid chamber during the pressure stroke can be individually adjusted. An expansion side valve chamber that communicates with the expansion side orifice and a compression side valve chamber that communicates with the compression side orifice are defined inside by a partition wall, and an expansion side check valve that opens in the axial direction during the compression stroke is provided in the expansion side valve chamber. A variable damping force type hydraulic shock absorber, characterized in that a pressure side check valve that opens in the axial direction during a pressure stroke is provided in the pressure side valve chamber.