JP6632923B2 - Shock absorber - Google Patents

Description

  The present invention relates to a hydraulic shock absorber.

  Conventionally, a cylinder filled with oil, a piston fitted slidably in the vertical direction on the inner circumference of the cylinder, a piston rod to which the piston is attached, and oil generated by sliding of the piston 2. Description of the Related Art A hydraulic shock absorber including a damping force generator that generates a damping force according to a flow is known. Generally, such a hydraulic shock absorber is provided with an oil reservoir for compensating oil for the volume integral of the piston rod and for the temperature expansion of the hydraulic oil when the piston rod enters and exits the cylinder. .

  When the oil reservoir is connected to a flow path branched from the flow path on the upstream side of the throttle that generates the damping force, the flow of oil generated by sliding of the piston is larger than that of the throttle having a large flow resistance. Head to the low resistance oil sump. Therefore, in order to allow only the oil corresponding to the volume of the piston rod to flow into the oil reservoir, it is necessary to provide a separate flow path resistance on the oil reservoir side. In this case, it is important to properly balance the flow path resistance between the oil reservoir and the throttle, and there is a problem that it is difficult to adjust the balance.

  Therefore, a hydraulic shock absorber provided with an oil reservoir downstream of the throttle has been realized. In such a hydraulic shock absorber, since the oil after being throttled by the throttle flows into the oil reservoir, it is not necessary to balance the flow path resistance between the oil reservoir and the throttle. Therefore, it becomes easy to flow the oil corresponding to the volume of the piston rod into the oil reservoir. Such a structure of the hydraulic shock absorber is referred to as a balance-free structure in this specification.

  A hydraulic shock absorber having a balance-free structure is described in, for example, Patent Document 1. The damping force generation device provided in the hydraulic shock absorber described in Patent Literature 1 generates a damping force when the oil flow generated by the movement of the piston passes through the compression side damping valve and the expansion side damping valve. The compression-side damping valve and the expansion-side damping valve are laminated valves, and the damping force characteristics when the moving speed of the piston is medium to high can be adjusted by changing the combination of the laminated valves. Further, the damping force generation device includes a compression side damping force adjustment valve and a growth side damping force adjustment valve that adjust the opening area of the bypass flow path that bypasses the compression side damping valve and the expansion side damping valve, respectively. The compression side damping force and the extension side damping force can be independently adjusted by the compression side damping force adjustment valve and the extension side damping force adjustment valve.

JP 2014-122710 A (released on July 3, 2014)

  In the damping force generation device described in Patent Literature 1, the entire adjustment can be performed for each of the compression-side damping force and the extension-side damping force as initial settings. However, according to the above adjustment, the entire curve of the damping force characteristic with respect to the speed of the piston changes. That is, the effect of the above adjustment affects both the case where the piston speed is high and the case where the piston speed is medium.

  Therefore, when the damping force is adjusted so that the damping force when the piston speed is high is appropriate, the damping force when the piston speed is medium speed may be insufficient. Conversely, when the damping force is adjusted so that the damping force when the piston speed is medium speed is appropriate, the damping force when the piston speed is high may be excessive.

  The present invention has been made in view of the above problems, and an object of the present invention is to increase the degree of freedom in setting a damping force for a hydraulic shock absorber having a balance-free structure.

In order to solve the above-described problems, a shock absorber according to the present invention includes:
A cylinder filled with oil,
A piston slidably fitted in the cylinder,
A piston rod connected to the piston and extending out of the cylinder;
When the piston rod enters the cylinder, an oil reservoir that compensates for the amount of oil corresponding to the volume of the piston rod,
A damping force generating device that generates a damping force in accordance with a flow of a fluid generated by sliding of the piston in the cylinder,
The damping force generator,
A compression damping valve that generates a damping force during the compression stroke,
A pressure-side check valve provided downstream of the pressure-side damping valve during a pressure-side stroke;
An extension damping valve that generates a damping force during the extension stroke,
An extension-side check valve provided downstream of the extension-side damping valve during the extension-side stroke;
A bypass flow path that branches off from the upstream side of the compression side damping valve during the compression side stroke and communicates with the oil sump chamber, and that branches off from the upstream side of the expansion side damping valve and communicates with the oil sump chamber during the expansion side stroke; ,
A compression-side damping force adjustment unit that adjusts the hydraulic pressure upstream of the compression-side damping valve during a compression-side stroke;
An extension-side damping force adjustment unit that adjusts the hydraulic pressure on the upstream side of the extension-side damping valve during the extension side stroke,
A space between the compression side damping valve and the compression side check valve is communicated with the oil reservoir,
A space between the extension side damping valve and the extension side check valve is communicated with the oil reservoir,
When the hydraulic pressure on the upstream side of the compression-side damping valve reaches a predetermined value during the compression-side stroke, the compression-side damping force adjustment unit increases the amount of oil flowing through the bypass flow path, and increases the oil amount in the expansion-side stroke. When the hydraulic pressure on the upstream side reaches a predetermined value, the extension-side damping force adjustment unit increases the amount of oil flowing through the bypass flow path ,
The bypass flow path has an opening into which oil branches off from the upstream side of the compression-side damping valve during the compression-side stroke, and into which oil flows, and oil flows into the expansion-side stroke from the upstream side of the expansion-side damping valve. ,
The compression-side damping force adjustment unit includes a compression-side adjustment valve that opens and closes and communicates with the upstream side of the compression-side damping valve by separating or seating in the opening of the bypass passage during the compression-side stroke,
The extension-side damping force adjustment unit has an extension-side adjustment valve that opens or closes and communicates with the upstream side of the extension-side damping valve by separating or sitting in the opening of the bypass flow path during the extension-side stroke. ,
The compression-side damping force adjustment unit further includes a compression-side air chamber that is filled with air and is set to an air pressure of a predetermined value that urges the compression-side adjustment valve in a valve closing direction. When the oil pressure on the upstream side is larger than the air pressure of the pressure side air chamber, the oil amount flowing through the bypass flow path is increased,
The expansion-side damping force adjustment unit is further filled with air, and further includes a expansion-side air chamber set to an air pressure of a predetermined value that urges the expansion-side adjustment valve in a valve closing direction, and the expansion-side stroke during the expansion-side stroke. hydraulic pressure in the upstream side of the extension side damping valve, if it becomes larger than the air pressure of the extension side air chamber, Ru increases the amount of oil flowing through the bypass passage.
Further, in order to solve the above problems, the shock absorber according to the present invention,
A cylinder filled with oil,
A piston slidably fitted in the cylinder,
A piston rod connected to the piston and extending out of the cylinder;
When the piston rod enters the cylinder, an oil reservoir that compensates for the amount of oil corresponding to the volume of the piston rod,
A damping force generating device that generates a damping force in accordance with a flow of a fluid generated by sliding of the piston in the cylinder,
The damping force generator,
A compression damping valve that generates a damping force during the compression stroke,
A pressure-side check valve provided downstream of the pressure-side damping valve during a pressure-side stroke;
An extension damping valve that generates a damping force during the extension stroke,
An extension-side check valve provided downstream of the extension-side damping valve during the extension-side stroke;
A bypass flow path that branches from the upstream side of the compression side damping valve during the compression side stroke and communicates with the oil sump chamber, and that branches off from the upstream side of the expansion side damping valve and communicates with the oil sump chamber during the expansion side stroke; ,
A compression-side damping force adjustment unit that adjusts the hydraulic pressure upstream of the compression-side damping valve during a compression-side stroke;
An extension-side damping force adjustment unit that adjusts the hydraulic pressure on the upstream side of the extension-side damping valve during the extension side stroke,
A space between the compression side damping valve and the compression side check valve is communicated with the oil reservoir,
A space between the extension side damping valve and the extension side check valve is communicated with the oil reservoir,
When the oil pressure on the upstream side of the compression side damping valve reaches a predetermined value during the compression side stroke, the compression side damping force adjustment unit increases the amount of oil flowing through the bypass flow path,
When the oil pressure on the upstream side of the expansion side damping valve reaches a predetermined value during the expansion side stroke, the expansion side damping force adjustment unit increases the amount of oil flowing through the bypass flow path,
The bypass flow passage has an opening into which oil branches off from the upstream side of the compression-side damping valve during the compression-side stroke, and into which oil flows in during the expansion-side stroke. ,
The compression-side damping force adjustment unit has a compression-side adjustment valve that opens and closes and communicates with the upstream side of the compression-side damping valve by being separated or seated in the opening of the bypass passage during the compression-side stroke,
The extension-side damping force adjustment unit has an extension-side adjustment valve that opens and closes and communicates with the upstream side of the extension-side damping valve by separating or sitting at the opening of the bypass flow path during the extension-side stroke. ,
The opening of the bypass flow path has a compression-side opening in which the compression-side adjustment valve can be seated during the compression-side stroke, and an extension-side opening in which the extension-side adjustment valve can be seated during the extension-side stroke,
The bypass flow path is formed in a tubular body,
The pressure side opening and the extension side opening are provided at both ends of the bypass flow path, respectively.

  ADVANTAGE OF THE INVENTION According to the shock absorber which concerns on this invention, about the hydraulic shock absorber which has a balance free structure, the degree of freedom of the setting of damping force can be improved.

It is a figure showing a flow of oil in a pressure side stroke of a shock absorber concerning an embodiment. It is a figure which shows the flow of oil in the extension side stroke of the shock absorber concerning an embodiment. It is a figure showing the example of the concrete composition of the buffer concerning an embodiment. It is a figure which shows the flow of oil when the moving speed of a piston is middle-high speed in the compression side stroke. FIG. 7 is a diagram showing the flow of oil when the moving speed of the piston is medium to high in the extension stroke. FIG. 3 is an exploded perspective view showing the structure of a compression side adjustment valve and a compression side adjuster. It is a graph which shows the damping force characteristic with respect to the speed of a piston of the shock absorber which concerns on embodiment. It is a figure which shows another embodiment of a damping force generator.

  Hereinafter, embodiments of the present invention will be described in detail.

[Embodiment 1]
(Overview of shock absorber 1)
FIG. 1 is a diagram illustrating a flow of oil in a compression side stroke of the shock absorber 1 according to the present embodiment. FIG. 2 is a diagram illustrating the flow of oil in the extension stroke of the shock absorber 1 according to the present embodiment. As shown in FIGS. 1 and 2, the shock absorber 1 includes a cylinder 10, a piston 11, a piston rod 14, an oil reservoir 25, and a damping force generator 20.

  Hydraulic oil is sealed in the cylinder 10. The piston 11 is slidably fitted in the cylinder 10. The inside of the cylinder 10 is partitioned by a piston 11 into a piston-side oil chamber 12 and a rod-side oil chamber 13. One end of the piston rod 14 is connected to the piston 11, and the other end of the piston rod 14 extends outside the cylinder 10. The oil storage chamber 25 is a tank for storing oil for compensating for the volume of the piston rod 14 that enters and exits the cylinder 10 and the amount of oil for the temperature expansion of hydraulic oil.

(Damping force generator 20)
The damping force generator 20 generates a damping force in accordance with a fluid flow generated by sliding of the piston 11 in the cylinder 10. As shown in FIGS. 1 and 2, the damping force generator 20 includes a compression side damping valve 21, a compression side check valve 22, an expansion side attenuation valve 23, an expansion side check valve 24, a compression side adjustment valve 26, and an expansion side adjustment valve 27. Is provided.

  The compression side damping valve 21 is a valve that generates a damping force during the compression side stroke, particularly when the piston rod 14 operates at medium to high speed.

  The compression side check valve 22 is a check valve provided downstream of the compression side damping valve 21 during the compression side stroke.

  The compression side adjustment valve 26 is a valve for adjusting the damping force in the compression side stroke. By adjusting the degree of opening of the opening where the pressure-side adjustment valve 26 is arranged, it is possible to adjust the damping force generated when oil passes through the opening.

  The extension-side damping valve 23 is a valve that generates a damping force during the extension-side stroke, particularly when the piston rod 14 operates at a medium to high speed.

  The extension side check valve 24 is a check valve provided downstream of the extension side damping valve 23 during the extension side stroke.

  The extension side adjustment valve 27 is a valve for adjusting the damping force in the extension side stroke. By adjusting the degree of opening of the opening in which the extension side adjustment valve 27 is arranged, it is possible to adjust the damping force generated when oil passes through the opening.

  The oil storage chamber 25 is provided with a bladder (not shown) filled with a high-pressure gas, and by the contraction of the bladder, the amount of oil entering the piston rod 14 and the temperature expansion of the hydraulic oil increases. Compensated. The oil reservoir 25 is provided downstream of the compression-side damping valve 21 and the extension-side damping valve 23. That is, the shock absorber 1 has a balance-free structure. For this reason, it is possible to avoid the damping force from dropping during the reversal from the compression stroke to the extension stroke.

(Oil flow in compression side stroke)
The oil flow in the compression side stroke will be described with reference to FIG. In FIG. 1, the flow of the oil is indicated by solid arrows. The thickness of the arrow corresponds to the oil flow rate.

  In the compression stroke, when the piston rod 14 enters the cylinder 10, the oil in the piston-side oil chamber 12 is pushed out by the piston 11 and supplied to the damping force generator 20.

  The oil supplied from the piston side oil chamber 12 to the damping force generation device 20 flows into the rod side oil chamber 13 mainly through the pressure side flow path passing through the pressure side damping valve 21 and the pressure side check valve 22. A compression damping force is generated by the flow path resistance when the oil passes through the compression damping valve 21.

  In addition, a part of the oil supplied from the piston side oil chamber 12 to the damping force generator 20 bypasses the compression side damping valve 21 and passes through the compression side bypass flow path via the compression side regulating valve 26 and the compression side check valve 22. And flows into the rod side oil chamber 13. At this time, the compression side damping force is also generated by the flow path resistance when the oil passes through the compression side adjustment valve 26.

  Further, part of the oil that has passed through either the compression-side damping valve 21 or the compression-side adjustment valve 26 flows into the oil reservoir 25. As a result, the oil corresponding to the volume of the piston rod 14 that has entered the rod-side oil chamber 13 is compensated.

(Oil flow in the extension side stroke)
The flow of oil in the extension stroke will be described with reference to FIG. In FIG. 2, the flow of the oil is indicated by broken arrows. The thickness of the arrow corresponds to the oil flow rate.

  In the extension stroke in which the piston rod 14 withdraws from the cylinder 10, the oil in the rod-side oil chamber 13 is pushed out by the piston 11 and supplied to the damping force generator 20.

  The oil supplied from the rod-side oil chamber 13 to the damping force generator 20 flows into the piston-side oil chamber 12 mainly through the expansion-side flow path passing through the expansion-side damping valve 23 and the expansion-side check valve 24. An expansion damping force is generated by the flow path resistance when the oil passes through the expansion damping valve 23.

  A part of the oil supplied from the rod-side oil chamber 13 to the damping force generator 20 bypasses the extension-side damping valve 23 and extends through the extension-side adjustment valve 27 and the extension-side check valve 24. It flows into the piston side oil chamber 12 through the flow path. At this time, the extension damping force is also generated by the flow path resistance when the oil passes through the extension adjustment valve 27.

  Further, the oil from the oil reservoir 25 joins the oil that has passed through either the expansion-side damping valve 23 or the expansion-side adjustment valve 27, and flows into the piston-side oil chamber 12. As a result, the oil corresponding to the retreated volume of the piston rod 14 retreated from the rod-side oil chamber 13 is compensated.

(Specific configuration of damping force generator 20)
FIG. 3 is a diagram illustrating an example of a specific configuration of the damping force generation device 20. As shown in FIG. 3, the damping force generator 20 includes a cylindrical valve case 30 and a cap 35 fitted to one end of the valve case 30. The valve case 30 sequentially accommodates the extension-side damping force adjustment unit 50, the valve unit 60, and the compression-side damping force adjustment unit 40 in the axial direction from one end to the other end.

(Valve section 60)
The valve section 60 includes, in the axial direction of the valve case 30, in order from one end side to the other end side, the compression side check valve 22, the second flow path forming member 62, the extension side attenuation valve 23, the intermediate member 63, and the compression side attenuation valve. 21, a first flow path forming member 61, and an extension side check valve 24. In the present embodiment, the compression-side check valve 22, the expansion-side attenuation valve 23, the compression-side attenuation valve 21, and the expansion-side check valve 24 are disk valves. The oil flows from the other end to the one end in the compression side stroke, and flows from one end to the other end in the extension side stroke.

  The first flow path forming member 61 is a disk-shaped member that contacts the inner peripheral surface of the valve case 30. The gap between the valve case 30 and the first flow path forming member 61 is sealed by a seal member 61a (see FIG. 4). The first flow path forming member 61 includes a first pressure side flow path 61b through which oil flows in the pressure side stroke, and a first expansion side flow path 61c through which oil flows in the expansion side stroke. The compression side damping valve 21 is provided on the downstream side of the first pressure side flow path 61b. The extension side check valve 24 is provided downstream of the first extension side flow path 61c.

  The second flow path forming member 62 is a disk-shaped member that contacts the inner peripheral surface of the valve case 30. The gap between the valve case 30 and the second flow path forming member 62 is sealed by a seal member 62a (see FIG. 4). The second flow path forming member 62 includes a second pressure side flow path 62b through which oil flows in the pressure side stroke, and a second expansion side flow path 62c through which oil flows in the expansion side stroke. The pressure side check valve 22 is provided downstream of the second pressure side flow path 62b. The extension side damping valve 23 is provided downstream of the second extension side flow path 62c.

  The intermediate member 63 is a disk-shaped member provided between the extension side damping valve 23 and the compression side damping valve 21 and having a diameter smaller than the inner diameter of the valve case 30. The intermediate member 63 is provided with a plurality of intermediate communication paths 63a extending in the radial direction.

  In the valve case 30, a space on the other end side of the first flow path forming member 61 is a pressure side oil chamber S1. The space on one end side of the second flow path forming member 62 becomes the extension-side oil chamber S3. The space between the first flow path forming member 61 and the second flow path forming member 62 becomes the intermediate oil chamber S2.

  That is, the compression side oil chamber S1 is an oil chamber on the upstream side of the compression side damping valve 21 in the compression side stroke. The expansion side oil chamber S3 is an oil chamber on the upstream side of the expansion side damping valve 23 in the expansion side stroke. The intermediate oil chamber S2 is an oil chamber between the pressure side damping valve 21 and the pressure side check valve 22. The intermediate oil chamber S2 is also an oil chamber between the expansion-side damping valve 23 and the expansion-side check valve 24.

  The valve case 30 is provided with a pressure-side inlet 31, an extension-side inlet 32, and an oil reservoir communication port 33. The compression-side inflow port 31 allows the piston-side oil chamber 12 to communicate with the compression-side oil chamber S1. The extension-side inlet 32 connects the rod-side oil chamber 13 and the extension-side oil chamber S3. The oil reservoir communication port 33 communicates the intermediate oil chamber S2 with the oil reservoir 25.

  Further, the valve section 60 further includes the tubular body 34. The tubular body 34 is a tubular member, and has a bypass passage 34a formed therein. The bypass passage 34a has a compression side opening 34b at the other end side into which oil branched from the upstream side of the compression side damping valve 21 flows in the compression side stroke, and branches off from the upstream side of the expansion side damping valve 23 in the expansion side stroke. One end has an extension side opening 34c into which oil flows. The compression-side adjustment valve 26 can be seated in the compression-side opening 34b, and the extension-side adjustment valve 27 can be seated in the extension-side opening 34c.

  The tubular body 34 further includes an intermediate opening 34d communicating with the intermediate communication path 63a. The intermediate oil chamber S2 and the bypass flow path 34a communicate with each other via the intermediate communication path 63a and the intermediate opening 34d. For this reason, the bypass flow passage 34a communicates with the intermediate oil chamber S2 during the compression side stroke and the expansion side stroke, and the intermediate oil chamber S2 communicates with the oil reservoir 25.

  The tubular body 34 includes a compression-side check valve 22, a second flow path forming member 62, an expansion-side damping valve 23, an intermediate member 63, a compression-side attenuation valve 21, a first flow path forming member 61, and an expansion-side check valve 24 from one end. Each in turn penetrates. That is, the bypass passage 34a is provided so as to penetrate these valves in order. In addition, the extension side adjustment valve 27, the extension side opening 34c, the compression side check valve 22, the second flow path forming member 62, the extension side attenuation valve 23, the intermediate member 63, the compression side attenuation valve 21, the first flow path formation member 61, The extension-side check valve 24, the compression-side opening 34b, and the compression-side adjustment valve 26 are provided coaxially in this order from one end.

  Further, the tubular body 34 has a housing portion 34e having an enlarged diameter on one end side. The accommodating portion 34e is a portion for accommodating the extension-side damping force adjusting portion 50 described later. The accommodation portion 34e is fitted in the cap 35. Further, a hole 34f is provided in the housing 34e. For this reason, the oil can enter the inside of the housing portion 34e, and the extension side oil chamber S3 and the inside of the housing portion 34e communicate with each other.

(Compression side damping force adjustment unit 40)
The compression side damping force adjustment unit 40 has a function of increasing the amount of oil flowing through the bypass passage 34a when the oil pressure of the compression side oil chamber S1 becomes higher than a predetermined value in the compression side stroke. The compression side damping force adjustment unit 40 includes a compression side cap 41, a compression side support 42, a compression side adjuster 43, and a compression side adjustment valve 26.

  The compression-side adjustment valve 26 is a needle valve that opens and closes the communication between the compression-side oil chamber S1 and the bypass passage 34a by separating or seating the distal end portion 26a in the compression-side opening 34b. The pressure-side adjustment valve 26 has a part that protrudes in the radial direction in a part in the axial direction, and a male screw 26b is formed in the part.

  The compression-side support 42 is a substantially cylindrical piston that supports the compression-side adjustment valve 26, and is disposed coaxially with the valve case 30. On the inner peripheral surface of the compression side support 42, a female screw 42b screwed with the male screw 26b of the compression side adjustment valve 26 is formed. A retaining ring 42 a is provided on the outer peripheral portion of the pressure-side support 42.

  The compression-side cap 41 is a member that is fitted into the other end of the valve case 30, and includes a compression-side annular groove 41 d into which the compression-side support 42 is fitted.

  A step 41b is formed in the compression-side annular groove 41d. The state in which the retaining ring 42a of the compression side support 42 is in contact with the step 41b is a state in which the compression side support 42 is inserted into the compression side cap 41 most deeply. In this state, the opening area of the pressure-side opening 34b is maximized.

  A retaining ring 41a is provided on the inner peripheral surface of the pressure-side cap 41 at a position facing the step 41b. The state where the retaining ring 42a of the compression side support 42 contacts the retaining ring 41a is the state where the compression side support 42 is fitted to the compression side cap 41 most shallowly.

  The compression-side annular groove 41d is sealed by seal members 41e and 41f (see FIG. 4) provided on the inner circumference and the outer circumference, respectively. A pressure side air chamber 44, which is a closed space surrounded by the pressure side annular groove 41 d and the pressure side support 42, is provided on the valve opening side of the pressure side adjustment valve 26. The compression side air chamber 44 is filled with air set to a predetermined value air pressure (high pressure) for urging the compression side adjustment valve 26 in the valve closing direction (the direction in which the compression side adjustment valve 26 is seated in the compression side opening 34b). ing. At the bottom of the pressure-side annular groove 41d, a pressure-side air adjustment portion 41c for adjusting the air pressure in the pressure-side air chamber 44 is provided. The air pressure in the compression-side air chamber 44 can be adjusted by the compression-side air adjustment unit 41c.

  Normally, the air pressure in the compression-side air chamber 44 is higher than the oil pressure in the compression-side oil chamber S1, so that the compression-side support body 42 is fixed with the retaining ring 42a in contact with the retaining ring 41a. When the oil pressure in the compression-side oil chamber S1 becomes higher than the air pressure in the compression-side air chamber 44, the retaining ring 42a separates from the retaining ring 41a, and the opening area of the compression-side opening 34b increases according to the oil pressure in the compression-side oil chamber S1. I do. That is, the opening of the compression-side adjustment valve 26 increases as the compression-side support 42 retreats. By this operation, the amount of oil flowing into the bypass passage 34a increases, and the amount of oil passing through the compression side damping valve 21 decreases. As a result, an increase in the damping force generated in the compression side damping valve 21 is suppressed.

  The opening area (opening degree) of the compression-side opening 34b is determined by the position of the tip 26a. By adjusting the opening area of the compression-side opening 34b, the compression-side damping force adjustment unit 40 can adjust the compression-side damping force.

  The compression side adjuster 43 is a member for the user to adjust the opening area of the compression side opening 34b. The compression side adjuster 43 is provided on the central axis of the valve case 30 of the compression side cap 41 so as to be exposed to the outside of the compression side cap 41. The compression-side adjuster 43 includes a seal member 43b (see FIG. 4) on an outer peripheral portion, and forms a seal surface between the compression-side adjuster 43 and the compression-side cap 41. A mechanism for adjusting the opening area of the compression-side opening 34b by the compression-side adjuster 43 will be described later.

(Extension side damping force adjustment unit 50)
The extension-side damping force adjustment unit 50 has a function of increasing the amount of oil flowing to the bypass passage 34a when the oil pressure in the extension-side oil chamber S3 becomes higher than a predetermined value in the extension-side stroke. The extension-side damping force adjustment unit 50 includes an extension-side cap 51, an extension-side support 52, an extension-side adjuster 53, and an extension-side adjustment valve 27.

  The extension side adjustment valve 27 is a needle valve that opens and closes the communication between the extension side oil chamber S3 and the bypass flow path 34a by separating or seating the distal end portion 27a in the extension side opening 34c during the extension side stroke. The extension-side adjustment valve 27 has a part that protrudes in the radial direction in a part in the axial direction, and a male screw 27b is formed in the part.

  The extension-side support 52 is a substantially cylindrical piston that supports the extension-side adjustment valve 27, and is disposed coaxially with the valve case 30. On the inner peripheral surface of the extension-side support member 52, a female screw 52b screwed with the male screw 27b of the extension-side adjustment valve 27 is formed. A retaining ring 52 a is provided on the outer peripheral portion of the extension-side support 52.

  The extension side cap 51 is a member that is fitted into the housing portion 34e, and includes a growth side annular groove 51d into which the extension side support 52 is fitted.

  A step 51b is formed in the extension-side annular groove 51d. The state in which the retaining ring 52a of the extension-side support 52 is in contact with the step 51b is a state in which the extension-side support 52 is inserted into the extension-side cap 51 most deeply. In this state, the opening area of the extension side opening 34c is maximized.

  A retaining ring 51a is provided on the inner peripheral surface of the extension side cap 51 at a position facing the step 51b. The state in which the retaining ring 52a of the extension-side support 52 is in contact with the retaining ring 51a is the state in which the extension-side support 52 is fitted to the extension-side cap 51 most shallowly.

  The extension-side annular groove 51d is sealed by seal members 51e and 51f (see FIG. 4) provided on the inner circumference and the outer circumference, respectively. A growth side air chamber 54, which is a closed space surrounded by the growth side annular groove 51 d and the growth side support 52, is provided on the valve opening side of the growth side adjustment valve 27. The expansion-side air chamber 54 is filled with air set at a predetermined air pressure that urges the expansion-side adjustment valve 27 in the valve closing direction (the direction in which the expansion-side adjustment valve 27 is seated in the expansion-side opening 34c). Have been. The predetermined value air pressure here may be the same as or different from the predetermined value air pressure in the pressure side air chamber 44. At the bottom of the extension-side annular groove 51d, an extension-side air adjustment portion 51c for adjusting the air pressure in the extension-side air chamber 54 is provided. The air pressure in the expansion-side air chamber 54 can be adjusted by the expansion-side air adjustment unit 51c.

  Normally, the air pressure in the expansion-side air chamber 54 is higher than the oil pressure in the expansion-side oil chamber S3, so that the expansion-side support 52 is fixed with the retaining ring 52a in contact with the retaining ring 51a. When the oil pressure in the extension-side oil chamber S3 becomes higher than the air pressure in the extension-side air chamber 54, the retaining ring 52a separates from the retaining ring 51a, and the opening area of the extension-side opening 34c increases the oil pressure in the extension-side oil chamber S3. Expand according to. That is, the extension of the extension-side adjustment valve 27 increases as the extension-side support 52 retreats. By this operation, the amount of oil flowing into the bypass flow passage 34a increases, and the amount of oil passing through the extension damping valve 23 decreases. As a result, an increase in the damping force generated in the extension side damping valve 23 is suppressed.

  The opening area (opening degree) of the extension side opening 34c is determined by the position of the tip 27a. By adjusting the opening area of the extension side opening 34c, the extension side damping force adjustment unit 50 can adjust the extension side damping force.

  The extension side adjuster 53 is a member for the user to adjust the opening area of the extension side opening 34c. The extension side adjuster 53 is located on the central axis of the valve case 30 of the extension side cap 51 and is provided so as to be exposed to the outside of the extension side cap 51. The extension-side adjuster 53 includes a seal member 53b (see FIG. 4) on the outer peripheral portion, and forms a seal surface between the extension-side adjuster 53 and the extension-side cap 51. A mechanism for adjusting the opening area of the extension side opening 34c by the extension side adjuster 53 will be described later.

(Oil flow when piston speed is lower than set value)
When the moving speed of the piston 11 is lower than the set value and the hydraulic pressures of the compression-side oil chamber S1 and the expansion-side oil chamber S3 are equal to or lower than the air pressures of the compression-side air chamber 44 and the expansion-side air chamber 54, respectively, the damping force generator 20 The flow of oil in the inside will be described with reference to FIG. Here, the “set value” of the moving speed of the piston 11 means that in the compression side stroke, the oil pressure in the compression side oil chamber S1 becomes larger than the air pressure in the compression side air chamber 44, and the retaining ring 42a of the compression side support 42 Is a speed at which the opening area of the pressure-side opening 34b starts to expand. Also, in the extension side stroke, the oil pressure in the extension side oil chamber S3 becomes larger than the air pressure in the extension side air chamber 54, the retaining ring 52a of the extension side support 52 separates from the retaining ring 51a, and the extension side opening. The speed at which the opening area of the portion 34c starts expanding. In FIG. 3, the oil flow in the compression stroke is indicated by a solid arrow, and the oil flow in the extension stroke is indicated by a broken arrow. The thickness of the arrow corresponds to the flow rate of the oil.

(Pressure side stroke)
In the compression side stroke, the oil in the piston side oil chamber 12 flows from the compression side inlet 31 into the compression side oil chamber S1. The oil flowing into the compression-side oil chamber S1 passes through the first pressure-side flow path 61b, pushes and opens the compression-side damping valve 21, and flows into the intermediate oil chamber S2. At this time, a damping force is generated by the flow path resistance in the compression side damping valve 21. In addition, a part of the oil flows from the pressure side oil chamber S1 to the intermediate oil chamber S2 via the pressure side opening 34b and the bypass flow path 34a. A damping force is generated when the oil passes through the gap between the compression side opening 34b and the compression side adjustment valve 26. In this compression side stroke, the compression side support 42 is fixed in a state where the retaining ring 42a is in contact with the retaining ring 41a.

  From the intermediate oil chamber S2, oil corresponding to the volume of the piston rod 14 that has entered the cylinder 10 flows to the oil reservoir 25 through the oil reservoir communication port 33. The other oil flows from the second pressure side flow path 62b through the pressure side check valve 22 to the expansion side oil chamber S3, and further flows through the expansion side inlet 32 to the rod side oil chamber 13.

(Extension side stroke)
In the extension side stroke, the oil in the rod side oil chamber 13 flows from the extension side inflow port 32 into the extension side oil chamber S3. The oil that has flowed into the expansion oil chamber S3 passes through the second expansion flow path 62c, pushes and opens the expansion damping valve 23, and flows into the intermediate oil chamber S2. At this time, a damping force is generated by the flow path resistance in the extension side damping valve 23. A part of the oil flows from the expansion-side oil chamber S3 to the intermediate oil chamber S2 via the expansion-side opening 34c and the bypass flow path 34a. A damping force is generated when the oil passes through the gap between the extension side opening 34c and the extension side adjustment valve 27. In the extension side stroke, the extension side support 52 is fixed with the retaining ring 52a in contact with the retaining ring 51a.

  At this time, the oil corresponding to the volume of the piston rod 14 retreated from the cylinder 10 flows from the oil reservoir 25 through the oil reservoir communication port 33 to the intermediate oil chamber S2. The oil in the intermediate oil chamber S2 flows from the first expansion side flow path 61c to the compression side oil chamber S1 through the expansion side check valve 24, and further flows to the piston side oil chamber 12 through the compression side inlet 31.

(Oil flow when piston speed is higher than set value)
The oil flow in the damping force generator 20 when the moving speed of the piston 11 is equal to or higher than the set value (medium speed) will be described with reference to FIGS.

  FIG. 4 is a diagram showing the flow of oil when the moving speed of the piston 11 is equal to or higher than a set value in the compression stroke. In this case, as shown in FIG. 4, the pressure-side adjustment valve 26 moves to the side (valve-opening side) that is separated from the pressure-side opening 34b, and the amount of oil flowing through the bypass passage 34a increases. As a result, the amount of oil flowing through the compression side damping valve 21 decreases, and the damping force generated in the compression side damping valve 21 decreases. Further, since the hydraulic pressure applied to the compression-side damping valve 21 is reduced, the possibility that the compression-side damping valve 21 is damaged is reduced. That is, the durability of the compression side damping valve 21 is improved.

  FIG. 5 is a view showing the flow of oil when the moving speed of the piston 11 in the extension stroke is equal to or higher than a set value. In this case, as shown in FIG. 5, the extension-side adjustment valve 27 moves to the side (valve-opening side) that is separated from the extension-side opening 34c, and the amount of oil flowing through the bypass flow path 34a increases. As a result, the amount of oil flowing through the extension side damping valve 23 decreases, so that the damping force generated in the extension side damping valve 23 decreases. Further, since the hydraulic pressure applied to the expansion-side damping valve 23 is reduced, the possibility that the expansion-side damping valve 23 is damaged is reduced. That is, the durability of the extension damping valve 23 is improved.

(Adjustment of the opening area of the compression side adjustment valve 26 and the extension side adjustment valve 27)
FIG. 6 is an exploded perspective view showing the structures of the compression side adjustment valve 26 and the compression side adjuster 43. A mechanism for adjusting the opening area of the compression side opening 34b by the compression side adjuster 43 will be described with reference to FIG.

  As shown in FIG. 6, the compression-side adjustment valve 26 has a fitting portion 26c that is fitted into the compression-side adjuster 43. The fitting portion 26c has a substantially flat plate shape. On the other hand, the pressure-side adjuster 43 includes a groove 43a into which the fitting portion 26c is fitted. The pressure-side adjustment valve 26 in which the fitting portion 26c is fitted into the groove 43a is freely movable in the axial direction, and the rotation of the pressure-side adjuster 43 around the axis is restricted. In other words, when the compression side adjuster 43 is rotated around the axis of the compression side adjustment valve 26, the compression side adjustment valve 26 also rotates.

  As described above, the compression side adjustment valve 26 is screwed to the compression side support 42. Therefore, when the user rotates the pressure-side adjuster 43, the pressure-side adjustment valve 26 moves in the axial direction with the rotation. Thereby, the relative position of the pressure side adjustment valve 26 with respect to the pressure side support 42 is adjusted, and the opening area of the pressure side opening 34b when the retaining ring 42a is in contact with the retaining ring 41a is adjusted. When the distal end 26a of the compression-side adjustment valve 26 is seated in the compression-side opening 34b, the compression-side opening 34b is closed, and the compression-side damping force generated by the compression-side damping valve 21 is maximized.

  The extension-side adjustment valve 27 and the extension-side adjuster 53 also have the same structure. When the user rotates the extension-side adjuster 53, the extension-side adjustment valve 27 moves in the axial direction with the rotation. Thereby, the relative position of the extension side adjustment valve 27 with respect to the extension side support body 52 is adjusted, and the opening area of the extension side opening 34c when the retaining ring 52a is in contact with the retaining ring 51a is adjusted. When the distal end 27a of the extension-side adjustment valve 27 is seated in the extension-side opening 34c, the extension-side opening 34c is closed, and the extension-side damping force generated by the extension-side damping valve 23 is maximized.

(Damping force characteristics of damping force generator 20)
FIG. 7 is a graph showing the damping force characteristics of the damping force generator 20. 7, the horizontal axis represents the piston speed of the piston 11, and the vertical axis represents the damping force. The moving speed of the piston 11 corresponds to the hydraulic pressure in the compression-side oil chamber S1 or the expansion-side oil chamber S3.

  The moving speed of the piston 11 at which the hydraulic pressure in the compression side oil chamber S1 or the expansion side oil chamber S3 becomes equal to the air pressure in the compression side air chamber 44 or the expansion side air chamber 54 is defined as Vth. When the movement speed of the piston 11 is in a low speed range, the magnitude of the damping force is determined mainly by the opening degree of the compression-side opening 34b or the extension-side opening 34c. When the moving speed of the piston 11 is in a middle to high speed range, the magnitude of the damping force is mainly determined by the compression-side damping valve 21 or the extension-side damping valve 23. That is, the value of the damping force generated by the compression-side damping valve 21 or the expansion-side damping valve 23 increases when the moving speed of the piston 11 is in a middle to high speed range. At this time, the influence of the degree of opening of the compression side opening 34b or the extension side opening 34c on the damping force is small.

  At this time, the hydraulic pressure in the compression-side oil chamber S1 or the expansion-side oil chamber S3 increases. However, when the moving speed of the piston 11 is lower than Vth, the compression-side support 42 and the extension-side support 52 do not move, and the opening areas of the compression-side opening 34b and the extension-side opening 34c do not increase.

  When a motorcycle or the like is running at a high speed, if the vehicle gets over a gap (projection) on the road surface, the moving speed of the piston 11 becomes higher than usual. In such a case, according to the conventional damping force generating device, as shown by (B) in FIG. 7, an excessive damping force is generated, and the riding comfort deteriorates. Further, at this time, the deflection of the compression-side damping valve 21 or the expansion-side damping valve 23 increases due to an increase in the pressure of the compression-side oil chamber S1 or the expansion-side oil chamber S3. Such a load becomes excessive. Therefore, the durability of the compression-side damping valve 21 and the extension-side damping valve 23 deteriorates.

  On the other hand, according to the damping force generating device 20 of the present embodiment, when the moving speed of the piston 11 becomes equal to or higher than Vth, the compression-side support 42 or the extension-side support 52 moves, and thereby the compression-side opening 34b or the compression-side opening 34b. The opening area of the side opening 34c increases, and more hydraulic fluid flows from the pressure side oil chamber S1 or the expansion side oil chamber S3 to the bypass flow path. Accordingly, the amount of oil passing through the compression-side damping valve 21 or the expansion-side damping valve 23 decreases, and the damping force generated in the compression-side damping valve 21 or the expansion-side damping valve 23 as shown in FIG. Is suppressed as compared with the case of FIG. 7B.

(Effect of the damping force generator 20)
As described above, according to the damping force generator 20, when the speed of the piston 11 has reached the predetermined value, that is, the hydraulic pressure on the upstream side of the compression-side damping valve 21 or the extension-side damping valve 23 has reached the predetermined oil pressure. Only in such a case can a part of the pressure be released (blown). For this reason, even if the damping force generated in the compression side damping valve 21 or the expansion side damping valve 23 is set so that the damping force when the speed of the piston 11 is medium speed is appropriate, the speed of the piston 11 is high. Excessive damping force in a certain case can be prevented. Therefore, the compression-side damping valve 21 or the extension-side damping valve 23 may be set so that the damping force generated when the speed of the piston 11 is medium speed becomes a preferable magnitude. That is, it is not necessary to consider the damping force when the speed is high.

  As described above, in the damping force generation device 20, it is possible to achieve both the setting of the damping force suitable for the case where the speed of the piston 11 is medium speed and the setting of the damping force suitable for the case where the speed is high. It is possible to increase the degree of freedom in setting the damping force.

  For example, when the load input to the shock absorber 1 is small due to unevenness of the road surface, that is, when the moving speed of the piston 11 is smaller than a predetermined value, a sufficient damping force can be obtained. On the other hand, when the load input to the shock absorber 1 from the road surface is large, that is, when the moving speed of the piston 11 is equal to or more than a predetermined value, the damping force generated in the compression-side damping valve 21 and the extension-side damping valve 23 is suppressed. You. For this reason, the riding comfort (absorption of unevenness) of a motorcycle or the like including the shock absorber 1 is improved.

  Further, according to the damping force generation device 20, when the load input to the shock absorber 1 is large, the load applied to the compression side damping valve 21 and the extension side damping valve 23 is suppressed. Thereby, the durability of the compression side damping valve 21 and the extension side damping valve 23 can be improved.

  In the shock absorber 1, the bypass flow path 34 a has openings (pressure side openings 34 b, growth side openings 34 c) into which oil branches off from the upstream side of the compression side damping valve 21 and the upstream side of the expansion side damping valve 23 and flows in. ). The compression-side damping force adjustment unit 40 is configured to open or close the upstream side of the compression-side damping valve 21 and the bypass passage 34a by separating or seating in the compression-side opening 34b of the bypass passage 34a during the compression-side stroke. 26. The extension-side damping force adjustment unit 50 opens and closes the upstream side of the extension-side damping valve 23 and the bypass passage 34a by separating or sitting in the extension-side opening 34c of the bypass passage 34a during the extension stroke. It has an extension-side adjustment valve 27 for making it extend.

  For this reason, the upstream side of the compression side damping valve 21 and the bypass flow passage 34a can be opened and closed freely by the compression side adjustment valve 26. Further, the upstream side of the expansion side damping valve 23 and the bypass flow passage 34a can be opened and closed freely by the expansion side adjustment valve 27.

  In the shock absorber 1, the opening of the bypass flow path 34a includes a compression-side opening 34b in which the compression-side adjustment valve 26 can be seated during the compression-side stroke, and an extension-side opening in which the extension-side adjustment valve 27 can be seated during the extension-side stroke. 34c.

  Therefore, the compression-side opening 34b and the extension-side opening 34c can be independently adjusted by the compression-side damping force adjustment unit 40 or the extension-side damping force adjustment unit 50.

  In the shock absorber 1, the bypass flow path 34a is formed in the tubular body 34, and the pressure side opening 34b and the extension side opening 34c are provided at both ends of the bypass flow path 34a, respectively. Therefore, the shock absorber 1 can have a simple structure.

  Further, in the shock absorber 1, the pressure side opening 34b and the extension side opening 34c in the bypass flow path 34a are provided coaxially. Therefore, the shock absorber 1 can have a simple structure.

  Further, in the shock absorber 1, the bypass flow path 34a is provided so as to penetrate therethrough in the order of the compression side check valve 22, the expansion side attenuation valve 23, the compression side attenuation valve 21, and the expansion side check valve 24. In addition, the extension side adjustment valve 27, the extension side opening 34c, the compression side check valve 22, the extension side attenuation valve 23, the compression side attenuation valve 21, the extension side check valve 24, the compression side opening 34b, and the compression side adjustment valve 26 are coaxially arranged in this order. It is provided in. Therefore, the shock absorber 1 can have a simple structure.

  Further, in the shock absorber 1, the compression-side damping force adjustment section 40 further includes a compression-side air chamber 44 filled with air and set to a predetermined air pressure that urges the compression-side adjustment valve 26 in the valve closing direction, When the oil pressure on the upstream side of the compression-side damping valve 21 becomes larger than the air pressure of the compression-side air chamber 44 during the compression-side stroke, the amount of oil flowing through the bypass flow passage 34a is increased. The expansion-side damping force adjustment unit 50 further includes an expansion-side air chamber 54 filled with air and set to a predetermined value air pressure that urges the expansion-side adjustment valve 27 in the valve closing direction. When the oil pressure on the upstream side of the expansion damping valve 23 becomes larger than the air pressure of the expansion air chamber 54 during the stroke, the amount of oil flowing to the bypass flow passage 34a is increased.

  Therefore, according to the damping force generation device 20, by adjusting the air pressure of the compression side air chamber 44, it is possible to easily adjust the predetermined value of the oil pressure of the compression side oil chamber S1 at which the compression side adjustment valve 26 opens. . Further, by adjusting the air pressure of the expansion-side air chamber 54, it is possible to easily adjust the predetermined value of the oil pressure of the expansion-side oil chamber S3 in which the expansion-side adjustment valve 27 opens.

[Embodiment 2]
In the above-described damping force generating device 20, the bypass flow path 34a has two openings, the compression-side opening 34b and the extension-side opening 34c. However, in the damping force generating device provided in the shock absorber according to the present invention, the bypass passage may have only a single opening.

  In the above-described damping force generator 20, the bypass flow path 34a is formed in the tubular body 34. However, in the damping force generating device provided in the shock absorber according to the present invention, the bypass passage may be formed other than the tubular body.

[Embodiment 3]
Further, the above-described shock absorber 1 includes a single cylinder 10. However, the shock absorber according to the present invention may be a shock absorber including an inner cylinder and an outer cylinder. In that case, the cylinder 10 in the above description corresponds to the inner cylinder. When the shock absorber 1 includes an inner cylinder and an outer cylinder, the inner cylinder may be provided on the axle side and the outer cylinder may be provided on the vehicle body, or vice versa. Such a shock absorber 1 is used for a front fork or a rear cushion of a motorcycle, for example.

[Embodiment 4]
FIG. 8 is a diagram showing another embodiment of the damping force generator provided in the shock absorber according to the present invention. The damping force generation device 20A shown in FIG. 8 is provided on the valve-opening side of the pressure-side adjustment valve 26 instead of the pressure-side air chamber 44, and closes the pressure-side adjustment valve 26 in the valve closing direction (the pressure-side adjustment valve 26 is placed in the pressure-side opening 34b). It has a compression-side metal spring 44A (pressure-side elastic body) that urges in the direction of seating. Further, the damping force generator 20A is provided on the valve-opening side of the extension-side adjustment valve 27 instead of the extension-side air chamber 54, and closes the extension-side adjustment valve 27 in the valve closing direction (when the extension-side adjustment valve 27 is extended The extension side metal spring 54A (extension side elastic body) that urges in the direction of being seated on the portion 34c).

  During the compression side stroke, the load acting on the valve opening side of the compression side adjustment valve 26 due to the oil pressure upstream of the compression side damping valve 21 becomes larger than the load (biasing force) acting on the valve closing side due to the elastic force of the compression side metal spring 44A. In this case, the opening degree of the pressure-side adjustment valve 26 increases, and the amount of oil flowing through the bypass passage 34a increases. Also, during the extension side stroke, the load acting on the valve opening side of the extension side adjustment valve 27 due to the oil pressure on the upstream side of the extension side damping valve 23 is the load acting on the valve closing side due to the elastic force of the extension side metal spring 54A. When the force becomes larger than the force, the opening of the extension-side adjustment valve 27 increases, and the amount of oil flowing through the bypass flow passage 34a increases.

  In the damping force generation device 20A, the compression side damping force adjustment unit 40 has a compression side metal spring 44A that urges the compression side adjustment valve 26 in the valve closing direction. The compression-side damping force adjustment unit 40 is configured to apply a load acting on the valve-opening side of the compression-side adjustment valve 26 due to the oil pressure upstream of the compression-side damping valve 21 during the compression-side stroke to a load acting on the valve closing side due to the elastic force of the compression-side metal spring 44A. When it becomes larger than the above, the amount of oil flowing to the bypass passage 34a is increased.

  Further, in the damping force generator 20A, the extension side damping force adjustment unit 50 has an extension side metal spring 54A that urges the extension side adjustment valve 27 in the valve closing direction. During the extension stroke, the load acting on the valve-opening side of the extension-side adjustment valve 27 due to the oil pressure upstream of the extension-side damping valve 23 is greater than the load acting on the valve-closing side due to the elastic force of the extension-side metal spring 54A. In this case, the amount of oil flowing to the bypass passage 34a is increased.

  In the shock absorber provided with the damping force generator 20A, by selecting a metal spring having an appropriate elastic force as the compression-side metal spring 44A and the extension-side metal spring 54A, the compression-side adjustment valve 26 and the extension-side adjustment valve 27 are opened. The respective predetermined values of the oil pressures of the pressure side oil chamber S1 and the expansion side oil chamber S3 at which the degree starts to increase can be adjusted. The damping force generating device provided in the shock absorber according to the present embodiment has a configuration in which the compression-side adjustment valve 26 and the extension-side adjustment valve 27 are urged in the valve closing direction by an elastic body made of a material different from a metal spring. Good.

  The present invention is not limited to the embodiments described above, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Cushion 10 Cylinder 11 Piston 14 Piston rod 20 Damping-force generator 21 Compression-side damping valve 22 Compression-side check valve 23 Extension-side attenuation valve 24 Extension-side check valve 25 Oil reservoir 26 Compression-side adjustment valve 27 Extension-side adjustment valve 34 Tubular body 34a Bypass flow path 34b Pressure side opening (opening)
34c extension side opening (opening)
40 compression side damping force adjustment section 44 compression side air chamber 44A compression side metal spring (compression side elastic body)
50 Extension side damping force adjustment unit 54 Extension side air chamber 54A Extension side metal spring (extension side elastic body)

Claims (7)

A cylinder filled with oil,
A piston slidably fitted in the cylinder,
A piston rod connected to the piston and extending out of the cylinder;
When the piston rod enters the cylinder, an oil reservoir that compensates for the amount of oil corresponding to the volume of the piston rod,
A damping force generating device that generates a damping force in accordance with a flow of a fluid generated by sliding of the piston in the cylinder,
The damping force generator,
A compression damping valve that generates a damping force during the compression stroke,
A pressure-side check valve provided downstream of the pressure-side damping valve during a pressure-side stroke;
An extension damping valve that generates a damping force during the extension stroke,
An extension-side check valve provided downstream of the extension-side damping valve during the extension-side stroke;
A bypass flow path that branches off from the upstream side of the compression side damping valve during the compression side stroke and communicates with the oil sump chamber, and that branches off from the upstream side of the expansion side damping valve and communicates with the oil sump chamber during the expansion side stroke; ,
A compression-side damping force adjustment unit that adjusts the hydraulic pressure upstream of the compression-side damping valve during a compression-side stroke;
An extension-side damping force adjustment unit that adjusts the hydraulic pressure on the upstream side of the extension-side damping valve during the extension side stroke,
A space between the compression side damping valve and the compression side check valve is communicated with the oil reservoir,
A space between the extension side damping valve and the extension side check valve is communicated with the oil reservoir,
When the oil pressure on the upstream side of the compression side damping valve reaches a predetermined value during the compression side stroke, the compression side damping force adjustment unit increases the amount of oil flowing through the bypass flow path,
When the oil pressure on the upstream side of the expansion side damping valve reaches a predetermined value during the expansion side stroke, the expansion side damping force adjustment unit increases the amount of oil flowing through the bypass flow path ,
The bypass flow path has an opening into which oil branches off from the upstream side of the compression-side damping valve during the compression-side stroke, and into which oil flows, and oil flows into the expansion-side stroke from the upstream side of the expansion-side damping valve. ,
The compression-side damping force adjustment unit includes a compression-side adjustment valve that opens and closes and communicates with the upstream side of the compression-side damping valve by separating or seating in the opening of the bypass passage during the compression-side stroke,
The extension-side damping force adjustment unit has an extension-side adjustment valve that opens or closes and communicates with the upstream side of the extension-side damping valve by separating or sitting in the opening of the bypass flow path during the extension-side stroke. ,
The compression-side damping force adjustment unit further includes a compression-side air chamber that is filled with air and is set to an air pressure of a predetermined value that urges the compression-side adjustment valve in a valve closing direction. When the oil pressure on the upstream side is larger than the air pressure of the pressure side air chamber, the oil amount flowing through the bypass flow path is increased,
The expansion-side damping force adjustment unit is further filled with air, and further includes a expansion-side air chamber set to an air pressure of a predetermined value that urges the expansion-side adjustment valve in a valve closing direction, and the expansion-side stroke during the expansion-side stroke. shock absorber oil pressure of the upstream side of the extension side damping valve, if it becomes larger than the air pressure of the extension side air chamber, characterized Rukoto increase the amount of oil flowing through the bypass passage. The opening of the bypass passage has a compression-side opening on which a compression-side adjustment valve can be seated during a compression-side stroke, and an extension-side opening on which the extension-side adjustment valve can be seated during an extension-side stroke. 2. The shock absorber according to 1 . A cylinder filled with oil,
A piston slidably fitted in the cylinder,
A piston rod connected to the piston and extending out of the cylinder;
When the piston rod enters the cylinder, an oil reservoir that compensates for the amount of oil corresponding to the volume of the piston rod,
A damping force generating device that generates a damping force in accordance with a flow of a fluid generated by sliding of the piston in the cylinder,
The damping force generator,
A compression damping valve that generates a damping force during the compression stroke,
A pressure-side check valve provided downstream of the pressure-side damping valve during a pressure-side stroke;
An extension damping valve that generates a damping force during the extension stroke,
An extension-side check valve provided downstream of the extension-side damping valve during the extension-side stroke;
A bypass flow path that branches off from the upstream side of the compression side damping valve during the compression side stroke and communicates with the oil sump chamber, and that branches off from the upstream side of the expansion side damping valve and communicates with the oil sump chamber during the expansion side stroke; ,
A compression-side damping force adjustment unit that adjusts the hydraulic pressure upstream of the compression-side damping valve during a compression-side stroke;
An extension-side damping force adjustment unit that adjusts the hydraulic pressure on the upstream side of the extension-side damping valve during the extension side stroke,
A space between the compression side damping valve and the compression side check valve is communicated with the oil reservoir,
A space between the extension side damping valve and the extension side check valve is communicated with the oil reservoir,
When the oil pressure on the upstream side of the compression side damping valve reaches a predetermined value during the compression side stroke, the compression side damping force adjustment unit increases the amount of oil flowing through the bypass flow path,
When the oil pressure on the upstream side of the expansion side damping valve reaches a predetermined value during the expansion side stroke, the expansion side damping force adjustment unit increases the amount of oil flowing through the bypass flow path,
The bypass flow path has an opening into which oil branches off from the upstream side of the compression-side damping valve during the compression-side stroke, and into which oil flows, and oil flows into the expansion-side stroke from the upstream side of the expansion-side damping valve. ,
The compression-side damping force adjustment unit includes a compression-side adjustment valve that opens and closes and communicates with the upstream side of the compression-side damping valve by separating or seating in the opening of the bypass passage during the compression-side stroke,
The extension-side damping force adjustment unit has an extension-side adjustment valve that opens or closes and communicates with the upstream side of the extension-side damping valve by separating or sitting in the opening of the bypass flow path during the extension-side stroke. ,
The opening of the bypass passage has a compression-side opening in which the compression-side adjustment valve can be seated during the compression-side stroke, and an extension-side opening in which the extension-side adjustment valve can be seated during the extension-side stroke,
The bypass flow path is formed in a tubular body,
Slow衝器and the pressure side opening and the extension side opening, you wherein each is provided on both ends of the bypass passage. The shock absorber according to claim 3 , wherein the compression side opening and the extension side opening in the bypass flow path are provided coaxially. The bypass flow path, the compression side check valve, the expansion side damping valve, the compression side attenuation valve, is provided to penetrate each in the order of the expansion side check valve,
The extension side adjustment valve, the extension side opening, the compression side check valve, the extension side damping valve, the compression side attenuation valve, the extension side check valve, the compression side opening, and the compression side adjustment valve are provided coaxially in this order. The shock absorber according to claim 4 , wherein the shock absorber is provided. The compression-side damping force adjustment unit has a compression-side elastic body that urges the compression-side adjustment valve in a valve closing direction, and acts on the valve-opening side of the compression-side adjustment valve by a hydraulic pressure upstream of the compression-side damping valve during a compression-side stroke. When the load to be applied is larger than the load acting on the valve closing side due to the elastic force of the compression-side elastic body, the amount of oil flowing through the bypass flow path is increased,
The extension-side damping force adjustment unit includes an extension-side elastic body that urges the extension-side adjustment valve in a valve-closing direction, and the extension-side adjustment valve that is driven by oil pressure upstream of the extension-side damping valve during an extension stroke. When the load acting on the valve-opening side becomes larger than the load acting on the valve-closing side due to the elastic force of the extension-side elastic body, the amount of oil flowing through the bypass flow path is increased. The shock absorber according to any one of claims 3 to 5 . The compression-side damping force adjustment unit further includes a compression-side air chamber that is filled with air and is set to an air pressure of a predetermined value that urges the compression-side adjustment valve in a valve closing direction. When the oil pressure on the upstream side is larger than the air pressure of the pressure side air chamber, the oil amount flowing through the bypass flow path is increased,
The expansion-side damping force adjustment unit is further filled with air, and further includes a expansion-side air chamber set to an air pressure of a predetermined value that urges the expansion-side adjustment valve in a valve closing direction, and the expansion-side stroke during the expansion-side stroke. hydraulic pressure in the upstream side of the extension side damping valve, if it becomes larger than the air pressure of the extension side air chamber, any claim 3-5, characterized in that increasing the amount of oil flowing through the bypass passage 2. The shock absorber according to claim 1.

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