Vehicle

Abstract

This vehicle comprises: a first force generation mechanism which is provided to a cylinder device disposed between a vehicle body and a wheel and in which a generated force is changeable by the relative movement of a cylinder and a rod; an elastic member which is disposed between the vehicle body and the wheel and which has rigidity that suppresses the transmission, to the vehicle body side, of high-frequency vibrations of 20 Hz and higher that are imparted to the wheel; and a second force generation mechanism which is provided to the cylinder device and which, when the movement speed of the rod relative to the cylinder is in a first speed range, operates in a state in which the first force generation mechanism is not operating, and when the movement speed of the rod relative to the cylinder is in a second speed range that is higher than the first speed range, operates together with the first force generation mechanism.

Description

Vehicle

[0001] The present disclosure relates to a vehicle.

[0002] A buffer (shock absorber) is provided between the vehicle body and the wheels of the vehicle (see, for example, Patent Document 1).

[0003] Japanese Patent No. 7168782

[0004] By the way, in a vehicle, there is a desire to improve the quietness in the vehicle interior and also improve the responsiveness of the vehicle behavior to steering input.

[0005] Therefore, an object of the present disclosure is to provide a vehicle capable of improving the quietness in the vehicle interior and improving the responsiveness of the vehicle behavior to steering input.

[0006] To achieve the above object, one aspect of the shock absorber of the present disclosure is provided in a cylinder device provided between the vehicle body and the wheels, a first force generation mechanism in which a force can be changed by relative movement between the cylinder and the rod, an elastic member provided between the vehicle body and the wheels and having a rigidity that suppresses transmission of high-frequency vibrations of 20 Hz or more transmitted to the wheels to the vehicle body side, and a second force generation mechanism provided in the cylinder device and operating in a state where the first force generation mechanism is not operating when the moving speed of the rod with respect to the cylinder is in a first speed region, and operating together with the first force generation mechanism when the moving speed of the rod with respect to the cylinder is in a second speed region higher than the first speed region.

[0007] According to the present disclosure, it is possible to improve the quietness in the vehicle interior and improve the responsiveness of the vehicle behavior to steering input.

[0008] This is a schematic front view showing the suspension structure for one wheel of a vehicle according to the embodiment of this disclosure. This is a mechanical model diagram of the suspension structure. This is a cross-sectional view showing the shock absorber of a vehicle according to the embodiment of this disclosure. This is a partial cross-sectional view showing the main part of the shock absorber. This is a partial cross-sectional view showing the main part of the shock absorber. This is a plan view showing the disc spring of the shock absorber. This is a plan view showing the flexible disc of the shock absorber. This is a partial cross-sectional view showing the operating state of the relief mechanism during the extension stroke of the shock absorber. This is a partial cross-sectional view showing the operating state of the relief mechanism during the compression stroke of the shock absorber. This is a system configuration diagram of a vehicle according to the embodiment of this disclosure. This is a characteristic diagram showing the ground load of the suspension structure as a function of time immediately after steering begins.

[0009] Figure 1 is a schematic front view showing the suspension structure 602 for one wheel 601 of a vehicle 600 in an embodiment that is in contact with the road surface R. The suspension structure 602 includes an axle 603 that rotates integrally with the wheel 601, a knuckle 604 that rotatably supports the axle 603, a shock absorber 1 (cylinder device) with one end connected to the knuckle 604 and the other end connected to the vehicle body 605, and a suspension spring 606 positioned between the shock absorber 1 and the vehicle body 605.

[0010] The shock absorber 1 has a cylinder 4 and a rod 25 that protrudes upward from the cylinder 4. The lower part of the cylinder 4 of the shock absorber 1 is connected to a knuckle 604. A spring support member 607 is fixed to the outer circumference of the cylinder 4. The spring support member 607 supports the lower end of the suspension spring 606. The upper end of the suspension spring 606 is connected to the vehicle body 605 via a spring retainer member 608. The upper end of the rod 25 is connected to the spring retainer member 608 via a cylindrical bush 610 (elastic member), and is connected to the vehicle body 605 via the spring retainer member 608. When the upper end of the rod 25 and the vehicle body 605 move relative to each other, the bush 610 undergoes elastic deformation.

[0011] Therefore, the shock absorber 1 is provided between the vehicle body 605 and the wheel 601. The bush 610 is also provided between the vehicle body 605 and the wheel 601. The suspension spring 606 is also provided between the vehicle body 605 and the wheel 601.

[0012] The wheel 601 has a metal wheel body 618 located radially inward and connected to the axle 603, and a rubber tire 619 located on the outer circumference that contacts the road surface R. The suspension structure 602 is a strut-type suspension structure for automobiles, but this is just one example, and various suspension structures can be applied as long as shock absorbers, bushings, and suspension springs are provided between the vehicle body 605 and the wheel 601.

[0013] Figure 2 is a mechanical model diagram of the suspension structure 602. The suspension structure 602 has a suspension spring 606, which is an elastic element, interposed between the vehicle body 605, which is a sprung mass component, and the unsprung mass component 622. The suspension structure 602 also has a shock absorber 1, which is a damper element, and a bush 610, which is an elastic element, arranged in series and interposed between the vehicle body 605 and the unsprung mass component 622. Here, the bush 610 is provided on the vehicle body 605 side of the shock absorber 1. The suspension structure 602 has a tire 619, which is an elastic element, between the unsprung mass component 622 and the road surface R. The unsprung mass component 622 includes a wheel 601, an axle 603, a knuckle 604, etc.

[0014] The bush 610 is an elastic member made of an elastic material, and its rigidity is set to suppress the transmission of high-frequency vibrations of 20 Hz or more transmitted from the road surface R to the wheel 601 to the vehicle body 605. The bush 610 is made of rubber material.

[0015] Next, the buffer 1 will be described mainly with reference to Figures 3 to 9. For the sake of explanation, in the following, the upper side in Figures 3 to 5, 8 and 9 will be referred to as "top," and the lower side in Figures 3 to 5, 8 and 9 will be referred to as "bottom" when describing the buffer 1.

[0016] <Configuration of buffer 1> As shown in Figure 3, buffer 1 is a double-cylinder type buffer comprising a cylinder 4 having a cylindrical inner cylinder 2 and a bottomed cylindrical outer cylinder 3 which has a larger diameter than the inner cylinder 2 and is provided radially outside the inner cylinder 2. The space between the outer cylinder 3 and the inner cylinder 2 is a reservoir chamber 5.

[0017] The outer cylinder 3 has a stepped cylindrical body member 8 whose axial ends are smaller in diameter than the axial middle section, and a bottom member 9 that closes one axial end of the body member 8. The side of the body member 8 opposite the bottom member 9 is an opening.

[0018] The shock absorber 1 includes an annular valve body 12 provided at one axial end of the inner cylinder 2, and an annular rod guide 13 provided at the other axial ends of the inner cylinder 2 and outer cylinder 3. The valve body 12 constitutes the base valve 15. The outer circumference of the base valve 15 is stepped. The outer circumference of the rod guide 13 is also stepped. The large diameter portion of the rod guide 13 is fitted into the body member 8.

[0019] One end of the inner cylinder 2 is fitted into the small-diameter portion of the outer circumference of the valve body 12. The inner cylinder 2 engages with the bottom member 9 of the outer cylinder 3 via the valve body 12. The other end of the inner cylinder 2 is fitted into the small-diameter portion of the outer circumference of the rod guide 13. The inner cylinder 2 engages with the body member 8 of the outer cylinder 3 via the rod guide 13. In this state, the inner cylinder 2 is positioned radially with respect to the outer cylinder 3. The space between the valve body 12 and the bottom member 9 communicates with the space between the inner cylinder 2 and the outer cylinder 3 via a passage groove 16 formed in the valve body 12, and, similar to the space between the inner cylinder 2 and the outer cylinder 3, constitutes the reservoir chamber 5.

[0020] The shock absorber 1 has an annular sealing member 18 on the side opposite to the bottom member 9 of the rod guide 13. This sealing member 18 is fitted to the inner circumference of the body member 8, similar to the rod guide 13. At the end of the body member 8 opposite to the bottom member 9, a locking portion 19 is formed by plastically deforming the body member 8 radially inward through crimping, such as curling. The sealing member 18 is sandwiched between this locking portion 19 and the rod guide 13. The sealing member 18 closes the opening of the outer cylinder 3. Specifically, the sealing member 18 is an oil seal.

[0021] The shock absorber 1 has a piston 21 provided inside the cylinder 4. The piston 21 is slidably mounted in the inner cylinder 2 of the cylinder 4. The piston 21 divides the inner cylinder 2 into two chambers: an upper chamber 22 and a lower chamber 23. The upper chamber 22 is provided between the piston 21 and the rod guide 13 inside the inner cylinder 2. The lower chamber 23 is provided between the piston 21 and the valve body 12 inside the inner cylinder 2. The lower chamber 23 is defined as a reservoir chamber 5 by the valve body 12. Inside the cylinder 4, the upper chamber 22 and the lower chamber 23 are sealed with oil liquid L as a working fluid. The reservoir chamber 5 is sealed with gas G as a working fluid and oil liquid L.

[0022] The shock absorber 1 is equipped with a rod 25. One end of the rod 25 is positioned inside the cylinder 4 and connected and fixed to the piston 21, while the other end extends outside the cylinder 4. The rod 25 is made of metal. The rod 25 passes through the upper chamber 22, but does not pass through the lower chamber 23. Therefore, the upper chamber 22 is the rod-side chamber through which the rod 25 passes, and the lower chamber 23 is the bottom-side chamber on the bottom member 9 side of the cylinder 4.

[0023] The piston 21 and rod 25 move together. During the extension stroke of the shock absorber 1, when the rod 25 increases the amount it protrudes from the cylinder 4, the piston 21 moves toward the upper chamber 22. During the contraction stroke of the shock absorber 1, when the rod 25 decreases the amount it protrudes from the cylinder 4, the piston 21 moves toward the lower chamber 23.

[0024] The rod guide 13 and the sealing member 18 are both annular in shape. The rod 25 is slidably inserted inside the rod guide 13 and the sealing member 18, respectively, and extends from the inside to the outside of the cylinder 4. One axial end of the rod 25 is fixed to the piston 21 inside the cylinder 4. The other axial end of the rod 25 protrudes outside the cylinder 4 via the rod guide 13 and the sealing member 18.

[0025] The rod guide 13 supports the rod 25 relative to the cylinder 4, allowing it to move axially while restricting its radial movement, and guides the movement of the rod 25. The outer circumference of the sealing member 18 is in close contact with the cylinder 4. The inner circumference of the sealing member 18 slides against the outer circumference of the rod 25 as it moves axially. As a result, the sealing member 18 prevents the oil L and gas G inside the cylinder 4 from leaking to the outside.

[0026] The rod 25 has a main shaft portion 27 and a mounting shaft portion 28 with a smaller diameter. The main shaft portion 27 is slidably fitted to the rod guide 13 and the sealing member 18. The mounting shaft portion 28 is located inside the cylinder 4 and connected to the piston 21, etc. The end of the main shaft portion 27 on the mounting shaft portion 28 side is a shaft step portion 29 that widens in a direction perpendicular to the axis.

[0027] A passage notch 30 extending in the axial direction is formed on the outer circumference of the mounting shaft portion 28 at an intermediate position in the axial direction, and a male thread 31 is formed at the tip position opposite to the main shaft portion 27 in the axial direction. The passage notch 30 is formed, for example, by cutting out the outer circumference of the mounting shaft portion 28 in a planar shape with a plane parallel to the central axis of the mounting shaft portion 28. The passage notch 30 can be formed in a so-called two-sided shape at two positions 180 degrees apart in the circumferential direction of the mounting shaft portion 28.

[0028] The shock absorber 1, for example, has a rod 25 with a protruding portion from the cylinder 4 positioned at the top and supported by the vehicle body, while the bottom member 9 of the cylinder 4 is positioned at the bottom and connected to the wheel side.

[0029] In the case of a single-tube type shock absorber in which a piston and a free piston are provided inside the cylinder, connected to a rod, the piston connected to the rod divides the inside of the cylinder into two chambers to which an oil liquid L is sealed, and the free piston divides one of these two chambers from a chamber to which gas is sealed, it is also possible to have the cylinder side supported by the vehicle body and the rod connected to the wheel side.

[0030] As shown in Figure 4, the piston 21 is composed of a metal piston body 36 that is in contact with and connected to the rod 25, and an annular synthetic resin sliding member 37 that is integrally mounted on the outer surface of the piston body 36 and slides inside the inner cylinder 2 of the cylinder 4.

[0031] The piston body 36 is provided with multiple passage holes 38 (only one is shown in Figure 4 due to the cross-sectional view) that can connect the upper chamber 22 and the lower chamber 23, and multiple passage holes 39 (only one is shown in Figure 4 due to the cross-sectional view).

[0032] Multiple passage holes 38 are formed at equal pitches in the circumferential direction of the piston body 36, with one passage hole 39 in between each, and constitute half of the total number of passage holes 38, 39. The multiple passage holes 38 have a crank shape with two bending points. The multiple passage holes 38 open radially inward on the lower chamber 23 side in the axial direction of the piston 21 compared to the upper chamber 22 side. The piston body 36 has an annular groove 55 formed on the lower chamber 23 side in the axial direction, which connects the multiple passage holes 38.

[0033] A first damping force generating mechanism 41 (first force generating mechanism) is provided on the lower chamber 23 side of the annular groove 55. The first damping force generating mechanism 41 opens and closes the passages in the annular groove 55 and the plurality of passage holes 38 to generate a damping force corresponding to the amount of valve opening. By positioning the first damping force generating mechanism 41 on the lower chamber 23 side, the passages in the plurality of passage holes 38 and the annular groove 55 become extension-side passages through which the oil liquid L flows from the upper chamber 22, which is the upstream side, to the lower chamber 23, which is the downstream side, during the movement of the piston 21 toward the upper chamber 22, that is, during the extension stroke. The first damping force generating mechanism 41 provided for these passages in the plurality of passage holes 38 and the annular groove 55 is an extension-side damping force generating mechanism that generates damping force by suppressing the flow of oil liquid L from the extension-side passages in the plurality of passage holes 38 and the annular groove 55 to the lower chamber 23. The first damping force generating mechanism 41 is provided in the shock absorber 1, and the generated force can be changed by the relative movement between the cylinder 4 and the rod 25.

[0034] The remaining half of the total number of passage holes 38, 39, are formed at equal pitches in the circumferential direction of the piston body 36, with one passage hole 38 in between each of them. The multiple passage holes 39 have a crank shape with two bending points. The multiple passage holes 39 open radially inward on the upper chamber 22 side in the axial direction of the piston 21 compared to the lower chamber 23 side. The piston body 36 has an annular groove 56 formed on the upper chamber 22 side in the axial direction that connects the multiple passage holes 39.

[0035] On the upper chamber 22 side of the annular groove 56, a first damping force generating mechanism 42 (first force generating mechanism) is provided, which opens and closes the passages in the multiple passage holes 39 and the annular groove 56 to generate a damping force corresponding to the amount of valve opening. By positioning the first damping force generating mechanism 42 on the upper chamber 22 side, the passages in the multiple passage holes 39 and the annular groove 56 become compression-side passages through which the oil liquid L flows from the upper chamber 22, which is the upstream side, to the upper chamber 22, which is the downstream side, during the movement of the piston 21 toward the lower chamber 23, that is, during the compression stroke. The first damping force generating mechanism 42 provided for these passages in the multiple passage holes 39 and the annular groove 56 is a compression-side damping force generating mechanism that generates damping force by suppressing the flow of oil liquid L from the passages in the multiple passage holes 39 and the annular groove 56 on the compression side to the upper chamber 22. The first damping force generating mechanism 42 is provided in the shock absorber 1, and the generated force can be changed by the relative movement between the cylinder 4 and the rod 25.

[0036] The piston body 36 has a roughly disc shape. An insertion hole 44 is formed in the axial direction through the radial center of the piston body 36, into which the mounting shaft portion 28 of the rod 25 is inserted. The insertion hole 44 has a small diameter hole portion 45 on one axial side into which the mounting shaft portion 28 of the rod 25 is fitted, and a large diameter hole portion 46 on the other axial side which is larger in diameter than the small diameter hole portion 45. The small diameter hole portion 45 is provided on the axial upper chamber 22 side, and the large diameter hole portion 46 is provided on the axial lower chamber 23 side. The piston 21 is positioned radially relative to the rod 25 by fitting the mounting shaft portion 28 into the small diameter hole portion 45.

[0037] At the axial end of the piston body 36 on the lower chamber 23 side, an annular inner seat portion 47 is formed radially inward from the opening of the annular groove 55 on the lower chamber 23 side of the piston body 36. At the axial end of the piston body 36 on the lower chamber 23 side, an annular valve seat portion 48, which constitutes part of the first damping force generating mechanism 41, is formed radially outward from the opening of the annular groove 55 on the lower chamber 23 side of the piston body 36.

[0038] At the axial end of the piston body 36 on the upper chamber 22 side, an annular inner seat portion 49 is formed radially inward from the opening of the annular groove 56 on the upper chamber 22 side of the piston body 36. At the axial end of the piston body 36 on the upper chamber 22 side, an annular valve seat portion 50, which constitutes part of the first damping force generating mechanism 42, is formed radially outward from the opening of the annular groove 56 on the upper chamber 22 side of the piston body 36.

[0039] The insertion hole 44 of the piston body 36 has a large-diameter hole portion 46 located axially closer to the inner seat portion 47 than the small-diameter hole portion 45. The passage within the large-diameter hole portion 46 of the piston body 36 is in constant communication with the rod passage portion 51 within the passage notch portion 30 of the rod 25, with their axial positions aligned.

[0040] In the piston body 36, the radially outer portion of the piston body 36 is stepped, with a lower axial height than the valve seat portion 48. The opening of the compression passage hole 39 on the lower chamber 23 side is located in this stepped portion. Similarly, in the piston body 36, the radially outer portion of the piston body 36 is stepped, with a lower axial height than the valve seat portion 50. The opening of the extension passage hole 38 on the upper chamber 22 side is located in this stepped portion.

[0041] The compression-side first damping force generating mechanism 42 includes the valve seat portion 50 of the piston 21. The first damping force generating mechanism 42 has, in order from the axial piston 21 side, one disc 63, multiple discs 64 of the same inner and outer diameter (specifically two discs), multiple discs 65 of the same inner and outer diameter (specifically three discs), multiple discs 66 of the same inner and outer diameter (specifically two discs), one disc 67, one disc 68, and one annular member 69. The discs 63-68 and the annular member 69 are made of metal and are all perforated circular flat plates of a certain thickness. The discs 63-68 and the annular member 69 are all positioned radially relative to the rod 25 by fitting a mounting shaft portion 28 inside each of them. The discs 63-68 are plain discs (flat discs without projections in the axial direction).

[0042] Disc 63 has an outer diameter larger than the outer diameter of the inner seat portion 49 of the piston 21 and smaller than the inner diameter of the valve seat portion 50. Disc 63 is always in contact with the inner seat portion 49. Multiple discs 64 have an outer diameter equivalent to the outer diameter of the valve seat portion 50 of the piston 21. Multiple discs 64 can seat on the valve seat portion 50. Multiple discs 65 have an outer diameter smaller than the outer diameter of disc 64. Multiple discs 66 have an outer diameter smaller than the outer diameter of disc 65. Disc 67 has an outer diameter smaller than the outer diameter of disc 66 and equivalent to the outer diameter of the inner seat portion 49 of the piston 21. Disc 68 has an outer diameter equivalent to the outer diameter of disc 65. The annular member 69 has an outer diameter smaller than the outer diameter of disc 68 and larger than the outer diameter of the axial step portion 29 of the rod 25. The annular member 69 is thicker and more rigid than the disks 63-68 and is in contact with the axial step portion 29.

[0043] A plurality of disks 64, a plurality of disks 65, and a plurality of disks 66 constitute a main valve 71 on the contraction side that can be seated and unseated on the valve seat portion 50. When the main valve 71 is unseated from the valve seat portion 50, it communicates the passages in the plurality of passage holes 39 and the annular groove 56 with the upper chamber 22, and suppresses the flow of the hydraulic fluid L between the main valve 71 and the valve seat portion 50 to generate a damping force. The annular member 69, together with the disk 68, abuts against the main valve 71 to restrict deformation of the main valve 71 beyond a specified amount in the opening direction.

[0044] The passages in the plurality of passage holes 39 and the annular groove 56, and the passage between the main valve 71 and the valve seat portion 50 that appears during valve opening are formed in the piston 21, and when the piston 21 moves toward the lower chamber 23 side, the hydraulic fluid L flows out from the lower chamber 23, which becomes the upstream side in the cylinder 4, to the upper chamber 22, which becomes the downstream side, to form a first passage 72 on the contraction side. The first damping force generation mechanism 42 on the contraction side that generates a damping force includes the main valve 71 and the valve seat portion 50. Therefore, the first damping force generation mechanism 42 is provided in the first passage 72. The first passage 72 is formed in the piston 21 including the valve seat portion 50. When the rod 25 and the piston 21 move to the contraction side, the hydraulic fluid L passes through the first passage 72.

[0045] The first damping force generation mechanism 41 on the extension side includes the valve seat portion 48 of the piston 21. The first damping force generation mechanism 41 includes, in order from the piston 21 side in the axial direction, one disk 82, one disk 83, a plurality of disks 84 (specifically, four disks) having the same inner diameter and the same outer diameter, one disk 85, a plurality of disks 86 (specifically, three disks) having the same inner diameter and the same outer diameter, and one disk 87. The disks 82 to 87 are made of metal and are all plane disks having a perforated circular flat shape with a constant thickness. The disks 82 to 87 all have a mounting shaft portion 28 fitted inside and are positioned radially with respect to the rod 25.

[0046] The disc 82 has an outer diameter that is larger than the outer diameter of the inner seat portion 47 of the piston 21 and smaller than the inner diameter of the valve seat portion 48. The disc 82 is in constant contact with the inner seat portion 47. As shown in Figure 5, the disc 82 has a notch 90 that allows the passages in the annular groove 55 and the multiple passage holes 38 to be in constant communication with the passage in the large diameter hole portion 46 of the piston 21 and the rod passage portion 51 in the passage notch 30 of the rod 25. The notch 90 is formed from an intermediate position outside the radial inner seat portion 47 to the inner peripheral edge. The notch 90 is formed during the press molding of the disc 82. The notch 90 is adjacent to and facing the large diameter hole portion 46 of the piston 21. The disc 83 has the same outer diameter as the disc 82 and does not have a notch like the disc 82. The multiple discs 84 have an outer diameter equivalent to the outer diameter of the valve seat portion 48 of the piston 21. Multiple discs 84 can seat on the valve seat portion 48. Disc 85 has an outer diameter smaller than the outer diameter of disc 84. Multiple discs 86 have an outer diameter smaller than the outer diameter of disc 85. Disc 87 has an outer diameter smaller than the outer diameter of disc 86 and slightly larger than the outer diameter of the inner seat portion 47 of the piston 21.

[0047] Multiple discs 84, one disc 85, and multiple discs 86 constitute the extension-side main valve 91, which can seat and detach from the valve seat portion 48. By separating from the valve seat portion 48, the main valve 91 connects the passages within the annular groove 55 and the multiple passage holes 38 to the lower chamber 23, and suppresses the flow of oil L between itself and the valve seat portion 48, thereby generating a damping force.

[0048] As shown in Fig. 4, passages in a plurality of passage holes 38 and in an annular groove 55, and a passage between a main valve 91 and a valve seat portion 48 that appears when the valve is opened are formed in a piston 21, and constitute a first passage 92 on the extension side through which hydraulic fluid L flows out from an upper chamber 22 on the upstream side in a cylinder 4 to a lower chamber 23 on the downstream side when the piston 21 moves to the upper chamber 22 side. A first damping force generating mechanism 41 on the extension side that generates a damping force includes the main valve 91 and the valve seat portion 48. Therefore, the first damping force generating mechanism 41 is provided in the first passage 92. The first passage 92 is formed in the piston 21 including the valve seat portion 48. When the rod 25 and the piston 21 move to the extension side, the hydraulic fluid L passes through the first passage 92.

[0049] As shown in Fig. 5, on the side opposite to the piston 21 of the first damping force generating mechanism 41 on the extension side, in order from the first damping force generating mechanism 41 side, there are one cap member 95, one disc spring 116 (biasing member), one disc 97, one flexible disc 100, one valve seat disc 101, one disc 102, one disc 103, one disc 104, one spring member 105, one disc 106, one sub-valve 107, one valve seat member 109 provided with one O-ring 108 on the outer peripheral side, one sub-valve 110, one disc 111, one spring member 112, one disc 113, and one annular member 114, which are provided by fitting the mounting shaft portion 28 of the rod 25 inside each of them. By fitting the mounting shaft portion 28 inside each of them, the cap member 95, disc spring 116, disc 97, flexible disc 100, valve seat disc 101, discs 102 to 104, spring member 105, disc 106, sub-valve 107, valve seat member 109, sub-valve 110, disc 111, spring member 112, disc 113, and annular member 114 are positioned radially with respect to the rod 25.

[0050] As shown in Fig. 4, a male thread 31 is formed on a portion of the mounting shaft portion 28 of the rod 25 that protrudes beyond the annular member 114. A nut 119 is screwed onto the male thread 31. The nut 119 abuts against the annular member 114.

[0051] As shown in Figure 4, the annular member 69, discs 63-68, piston 21, discs 82-87, cap member 95, disc spring 116 shown in Figure 5, disc 97, flexible disc 100, valve seat disc 101, discs 102-104, spring member 105, disc 106, sub-valve 107, valve seat member 109, sub-valve 110, disc 111, spring member 112, disc 113, and annular member 114 are fixed to the rod 25 by being clamped axially by the axial step portion 29 of the rod 25 and the nut 119, at least on the radially inner circumference side. In this state, as shown in Figure 5, the disc spring 116, the disc 97, the flexible disc 100, the valve seat disc 101, the discs 102-104, the spring member 105, the disc 106, the sub-valve 107, the valve seat member 109, the sub-valve 110, the disc 111, the spring member 112, and the disc 113 are arranged inside the cap member 95.

[0052] The cap member 95, discs 97, 102-104, 106, 111, 113, flexible disc 100, valve seat disc 101, spring members 105, 112, sub-valves 107, 110, valve seat member 109, annular member 114, and disc spring 116 are all made of metal. The discs 97, 102-104, 106, 111, 113, flexible disc 100, valve seat disc 101, sub-valves 107, 110, and annular member 114 are all plain discs in the shape of perforated circular plates of a certain thickness. The cap member 95, valve seat member 109, and disc spring 116 are annular. The spring members 105 and 112 are annular.

[0053] The cap member 95 is a bottomed cylindrical integrally molded product. The cap member 95 is formed, for example, by plastic deformation or cutting of a metal plate. The cap member 95 has a perforated disc-shaped bottom portion 122 of a constant thickness, an intermediate curved portion 123 that extends from the outer peripheral edge of the bottom portion 122 while expanding in diameter on one side in the axial direction of the bottom portion 122, and a cylindrical tubular portion 124 that extends from the end edge of the intermediate curved portion 123 opposite to the bottom portion 122 in the direction opposite to the bottom portion 122.

[0054] The bottom portion 122 is a perforated circular plate with a constant radial width around its entire circumference. The mounting shaft portion 28 of the rod 25 is fitted into the inner circumference of the bottom portion 122. By fitting the mounting shaft portion 28 into the inner circumference of the bottom portion 122, the cap member 95 is positioned radially relative to the rod 25 and arranged coaxially. Multiple passage holes 126 are formed in the bottom portion 122 between its inner and outer circumferences, penetrating the bottom portion 122 in the axial direction. The multiple passage holes 126 are arranged at equal intervals in the circumferential direction of the bottom portion 122 at positions equidistant from the center of the bottom portion 122. The cap member 95 is positioned such that the bottom portion 122 is located on the piston 21 side of the cylindrical portion 124 and is in contact with the disc 87. The cap member 95 is fitted onto the mounting shaft portion 28 at the inner circumference of the bottom portion 122.

[0055] The intermediate curved portion 123 is an annular shape coaxial with the bottom portion 122. The intermediate curved portion 123 has a curved shape in which the cross-section of the plane containing its central axis is radially outward and convex toward the bottom portion 122 in the axial direction. The cylindrical portion 124 is also coaxial with the bottom portion 122 and the intermediate curved portion 123.

[0056] The cap member 95, along with its closed-bottom cylindrical shape, has higher rigidity than the discs 84-86. Therefore, the cap member 95 restricts deformation of the main valve 91, which is composed of multiple discs 84-86, in the opening direction beyond a specified limit by contacting the main valve 91.

[0057] The disc spring 116 is a perforated circular plate made of metal and is flexible. The disc spring 116 is formed from a single sheet of material by press forming, punching, and bending. As shown in Figure 6, the disc spring 116 has an inner annular portion 401, an intermediate annular portion 402, an outer conical portion 403, and a plurality of support portions 404, specifically two, that connect the inner annular portion 401 and the intermediate annular portion 402. The inner annular portion 401 is a perforated circular flat plate. The intermediate annular portion 402 is a perforated circular flat plate having an inner diameter larger than the outer diameter of the inner annular portion 401. The two support portions 404 are provided between the inner annular portion 401 and the intermediate annular portion 402. The inner annular portion 401, the intermediate annular portion 402, and the two support portions 404 are flat plates arranged on the same plane. The outer conical portion 403 is a conical cylinder that extends radially outward and axially in one direction from the outer peripheral edge of the intermediate annular portion 402. The outer diameter side of the disc spring 116 is the outer conical portion 403. The inner diameter side of the disc spring 116 is an inner planar portion 414 having an inner annular portion 401, an intermediate annular portion 402, and two support portions 404. The inner planar portion 414 is closer to a plane than the outer conical portion 403.

[0058] As shown in Figure 5, the outer diameter of the outer conical portion 403 of the disc spring 116, i.e., the outer diameter of the disc spring 116, is slightly smaller than the inner diameter of the cylindrical portion 124 of the cap member 95. The inner annular portion 401, the intermediate annular portion 402, and the two support portions 404 abut against the bottom portion 122 of the cap member 95. The outer conical portion 403 extends axially on the same side as the cylindrical portion 124. In this state, the disc spring 116 is positioned radially relative to the rod 25 by fitting the mounting shaft portion 28 to the inner circumference side of the inner annular portion 401. The disc spring 116 is formed so that its inner end abuts against the rod 25. The cylindrical portion 124 of the cap member 95 is positioned radially outward of the disc spring 116.

[0059] As shown in Figure 6, the inner annular portion 401, the intermediate annular portion 402, and the outer conical portion 403 all have a constant radial width around their entire circumference. The radial width of the outer conical portion 403 is wider than that of the inner annular portion 401. The radial width of the inner annular portion 401 is wider than that of the intermediate annular portion 402. The inner annular portion 401, the intermediate annular portion 402, and the outer conical portion 403 are arranged coaxially. Two support parts 404 connect the inner annular portion 401, the intermediate annular portion 402, and the outer conical portion 403 in a coaxial manner. The two support parts 404 connect the outer peripheral edge of the inner annular portion 401 and the inner peripheral edge of the intermediate annular portion 402.

[0060] The two support portions 404 have two outer connecting portions 411 that are arranged on the same straight line passing through the center of the inner annular portion 401, the intermediate annular portion 402, and the outer conical portion 403, in other words, the center of the disc spring 116. These outer connecting portions 411 are connected to the intermediate annular portion 402. The two outer connecting portions 411 are arranged with a 180-degree phase difference in the circumferential direction of the intermediate annular portion 402. Both outer connecting portions 411 protrude radially inward from the inner peripheral edge of the intermediate annular portion 402.

[0061] The two support portions 404 each have two inner connection portions 412 that are arranged on the same straight line passing through the center of the disc spring 116. These inner connection portions 412 are connected to the inner annular portion 401. The two inner connection portions 412 are arranged with a 180-degree phase difference in the circumferential direction of the inner annular portion 401. Both inner connection portions 412 protrude radially outward from the outer peripheral edge of the inner annular portion 401. In both cases, the circumferential distance of the disc spring 116 from the first inner connection portion 412 is shorter than the distance from the second inner connection portion 412. In other words, in both cases, the circumferential distance of the disc spring 116 from the first outer connection portion 411 is shorter than the distance from the second outer connection portion 411.

[0062] The circumferential distance between the outer connecting portion 411 and the inner connecting portion 412 on the first side of the disc spring 116 is the same as the circumferential distance between the outer connecting portion 411 and the inner connecting portion 412 on the second side of the disc spring 116.

[0063] The two support portions 404 are provided with two connecting arms 413 to connect the outer connecting portion 411 and the inner connecting portion 412. Specifically, the disc spring 116 is provided with a first connecting arm 413 that connects the outer connecting portion 411 and the inner connecting portion 412 on the first side in the circumferential direction of the disc spring 116. These outer connecting portion 411, inner connecting portion 412, and connecting arm 413 constitute the first support portion 404. The disc spring 116 is provided with a second connecting arm 413 that connects the outer connecting portion 411 and the inner connecting portion 412 on the second side in the circumferential direction of the disc spring 116. These outer connecting portion 411, inner connecting portion 412, and connecting arm 413 constitute the second support portion 404.

[0064] The first and second connecting arms 413 extend in an arc shape along the outer circumferential surface of the inner annular portion 401 and the inner circumferential surface of the intermediate annular portion 402. The first and second connecting arms 413 are arranged on the same circle, concentric with the inner annular portion 401, the intermediate annular portion 402, and the outer conical portion 403. Each of the first and second connecting arms 413 extends in an angular range slightly less than 180° in the circumferential direction of the disc spring 116. The radial distance of the first and second connecting arms 413 from the inner circumferential surface of the intermediate annular portion 402 is greater than the radial distance from the outer circumferential surface of the inner annular portion 401.

[0065] The disc spring 116, having the shape described above, is surrounded by the inner annular portion 401, the intermediate annular portion 402, and the two support portions 404, forming two stepped arc-shaped holes 415. The two holes 415 penetrate the disc spring 116 in the thickness direction (axial direction). The two holes 415 are provided between the inner annular portion 401 and the intermediate annular portion 402. Therefore, the disc spring 116 has two stepped arc-shaped holes 415 between the inner end and the outer end. The two stepped arc-shaped holes 415 are provided in the inner planar portion 414.

[0066] The two holes 415 are identical in shape. The two holes 415 have an arc-shaped small-diameter hole 421 formed between the inner annular portion 401 and the connecting arm portion 413, an arc-shaped large-diameter hole 422 formed between the intermediate annular portion 402 and the connecting arm portion 413, and a connecting hole 423 that connects the small-diameter hole 421 and the large-diameter hole 422. Both the small-diameter hole 421 and the large-diameter hole 422 are arc-shaped and coaxial with the inner annular portion 401 and the intermediate annular portion 402. The large-diameter hole 422 is an arc-shaped hole with a larger diameter than the small-diameter hole 421. The holes 415 are arranged so that the large-diameter hole 422 and the small-diameter hole 421 are adjacent to each other in the circumferential direction. The sides of the large-diameter hole 422 and the small-diameter hole 421 that are close to each other are connected by a connecting hole 423 that runs along the radial direction of the disc spring 116.

[0067] As shown in Figure 5, the inner diameter of the intermediate annular portion 402 of the disc spring 116 is smaller than twice the longest distance connecting the radial center of the cap member 95 and the passage hole 126, and larger than twice the shortest distance connecting the radial center of the cap member 95 and the passage hole 126. Therefore, the communication passage 425 in the hole portion 415 of the disc spring 116 is always in communication with the communication passage 148 in the passage hole 126 of the bottom portion 122. The portion of the communication passage 425 in the hole portion 415 of the disc spring 116 within the large-diameter hole portion 422 shown in Figure 6 is always in communication with the communication passage 148 in the passage hole 126. As shown in Figure 4, the outer diameter of the intermediate annular portion 402 of the disc spring 116, that is, the inner diameter of the outer conical portion 403, is larger than twice the longest distance connecting the radial center of the cap member 95 and the passage hole 126. The disc spring 116 has an intermediate annular portion 402 that abuts around the entire circumference of the bottom portion 122 of the cap member 95 at a position radially outward from all of the passage holes 126 of the bottom portion 122.

[0068] The disc 97 has a constant radial width around its entire circumference. The outer diameter of the disc 97 is smaller than the outer diameter of the inner annular portion 401 of the disc spring 116. The disc 97 is thicker than the thickness of the inner annular portion 401 of the disc spring 116, i.e., the plate thickness of the disc spring 116.

[0069] The inner annular portion 401 of the disc spring 116 is clamped axially by the bottom portion 122 of the cap member 95 and the disc 97 shown in Figure 5. This fixes the disc spring 116 to the rod 25. The two support portions 404 and the intermediate annular portion 402 shown in Figure 6 contact the bottom portion 122 of the cap member 95 shown in Figure 5, but do not contact the disc 97. Therefore, the two support portions 404 and the intermediate annular portion 402 are not clamped axially.

[0070] The flexible disc 100 is flexible. The inner circumference of the flexible disc 100 abuts against the rod 25. The outer diameter of the flexible disc 100 is larger than the outer diameter of the disc spring 116 and slightly smaller than the inner diameter of the cylindrical portion 124 of the cap member 95. The flexible disc 100 has a thickness equivalent to the plate thickness of the disc spring 116.

[0071] The flexible disc 100 is formed from a single sheet of material by press forming and punching. In its natural state before being assembled to the rod 25, the flexible disc 100 is flat. As shown in Figure 7, the flexible disc 100 has a constant radial width around its entire circumference. Multiple communication holes 501, specifically 15 in total, are formed in the flexible disc 100 at intermediate radial positions. All communication holes 501 are round holes of the same diameter and penetrate the flexible disc 100 in the thickness direction (axial direction). All communication holes 501 are formed at equidistant positions from the center of the flexible disc 100. All communication holes 501 are formed at equal intervals in the circumferential direction of the flexible disc 100.

[0072] The flexible disc 100 has multiple communication holes 501 formed therein, and has an inner annular portion 502 from the inner peripheral edge to the communication holes 501, an outer annular portion 503 from the outer peripheral edge to the communication holes 501, and a connecting portion 504 that extends radially across the flexible disc 100 and connects the inner annular portion 502 and the outer annular portion 503. The inner annular portion 502 has a constant radial width throughout its entire circumference. The outer annular portion 503 also has a constant radial width throughout its entire circumference. The outer annular portion 503 has a greater radial width than the inner annular portion 502.

[0073] The connecting portion 504 is located between adjacent communication holes 501 in the circumferential direction of the flexible disk 100. Therefore, multiple connecting portions 504 are formed at the intermediate radial positions of the flexible disk 100, specifically at 15 locations, the same number as the communication holes 501. All connecting portions 504 are the same shape and are formed at equidistant positions from the center of the flexible disk 100. All connecting portions 504 are formed at equal intervals in the circumferential direction of the flexible disk 100. As shown in Figure 5, the outer diameter of the inner annular portion 502 of the flexible disk 100 is larger than the outer diameter of the disk 97. Therefore, the communication holes 501 of the flexible disk 100 are not blocked by the disk 97.

[0074] The disc spring 116 has a circular edge on the side of the outer conical portion 403 that is opposite to the intermediate annular portion 402. This circular edge contacts the outer peripheral edge side of the outer annular portion 503 of the flexible disc 100 around its entire circumference.

[0075] The valve seat disc 101 has a constant radial width around its entire circumference. In its natural state before being assembled to the rod 25, the valve seat disc 101 is flat. The valve seat disc 101 is slightly thinner than the flexible disc 100. The outer diameter of the valve seat disc 101 is larger than the inner diameter of the outer annular portion 503 of the flexible disc 100, and smaller than the outer diameter of the outer annular portion 503. When the valve seat disc 101 makes surface contact with the outer annular portion 503 of the flexible disc 100 around its entire circumference, it closes all of the communication holes 501.

[0076] Disk 102 has the same shape as disk 97 and is interchangeable. Disk 102, together with disk 97, clamps the inner circumference of the flexible disk 100 and the valve seat disk 101 in the axial direction.

[0077] The disc 103 has a constant radial width around its entire circumference. The outer diameter of the disc 103 is larger than the outer diameter of the disc 102 and smaller than the outer diameter of the valve seat disc 101. The disc 103 has a thickness equivalent to that of the flexible disc 100.

[0078] The disc 104 has a constant radial width around its entire circumference. The outer diameter of the disc 104 is larger than that of the valve seat disc 101 and smaller than that of the flexible disc 100. The disc 104 has a thickness equivalent to that of discs 97 and 102. The disc 104 is thicker and more rigid than the flexible disc 100 and the valve seat disc 101.

[0079] The spring member 105 has a perforated circular flat base plate portion 331 that fits onto the mounting shaft portion 28, and a plurality of spring plate portions 332 that extend radially outward from the base plate portion 331 from equally spaced positions in the circumferential direction of the base plate portion 331. The spring plate portions 332 are inclined with respect to the base plate portion 331 such that they move further away from the base plate portion 331 in the axial direction of the base plate portion 331 as they extend toward the sub-valve 107. The spring member 105 abuts against the disk 104 at the base plate portion 331. The spring member 105 is attached to the mounting shaft portion 28 such that the spring plate portions 332 extend toward the sub-valve 107 side in the axial direction of the base plate portion 331.

[0080] The outer diameter of the disc 106 is smaller than the outer diameter of the base portion 331 of the spring member 105, but larger than the outer diameter of the disc 102. The base portion 331 of the spring member 105 abuts against the disc 106. Multiple spring plate portions 332 of the spring member 105 abut against the sub-valve 107.

[0081] As shown in Figure 4, the valve seat member 109 is a perforated disc. The valve seat member 109 has a through hole 131 in the radial center that extends axially and penetrates through the thickness direction for inserting the mounting shaft portion 28. The through hole 131 has a small diameter hole portion 132 on one axial side for fitting the mounting shaft portion 28 of the rod 25, and a large diameter hole portion 133 on the other axial side which is larger in diameter than the small diameter hole portion 132.

[0082] The valve seat member 109 has an annular inner seat portion 134 at the end on the axial side of the large diameter hole portion 133, surrounding the large diameter hole portion 133. The valve seat member 109 has a valve seat portion 135 that extends radially outward from this inner seat portion 134. The valve seat member 109 has an annular inner seat portion 138 at the end on the opposite axial side of the small diameter hole portion 132, surrounding the small diameter hole portion 132. The valve seat member 109 has a valve seat portion 139 that extends radially outward from this inner seat portion 138. The valve seat member 109 has a perforated disc-shaped main body portion 140 between its axial inner seat portion 134 and valve seat portion 135 and the inner seat portion 138 and valve seat portion 139.

[0083] The inner seat portion 134 protrudes to one side along the axial direction of the main body portion 140 from the inner peripheral edge on the axial side of the large diameter hole portion 133 of the main body portion 140. The valve seat portion 135 also protrudes from the main body portion 140 to the same side as the inner seat portion 134, along the axial direction of the main body portion 140, radially outward from the inner seat portion 134. The inner seat portion 134 and the valve seat portion 135 have flat tip surfaces on the protruding side, that is, the tip surfaces opposite to the main body portion 140. The inner seat portion 134 and the valve seat portion 135 are arranged on the same plane, spreading out in a direction perpendicular to the axis of the valve seat member 109.

[0084] The inner seat portion 138 protrudes from the inner peripheral edge of the main body portion 140 on the side of the axially small diameter hole portion 132, along the axial direction of the main body portion 140, on the side opposite to the inner seat portion 134. The valve seat portion 139 also protrudes radially outward from the inner seat portion 138, along the axial direction of the main body portion 140, on the same side as the inner seat portion 138. The inner seat portion 138 and the valve seat portion 139 have flat tip surfaces on the protruding side, i.e., the tip surfaces opposite to the main body portion 140. The inner seat portion 138 and the valve seat portion 139 are arranged on the same plane, spreading out in a direction perpendicular to the axis of the valve seat member 109. The inner seat portions 134 and 138 have equivalent outer diameters.

[0085] The valve seat portion 135 is a petal-shaped irregular seat. The valve seat portion 135 has multiple valve seat components 201 (only one is shown in Figure 4 due to the cross-sectional view). These valve seat components 201 are the same shape and are arranged at equal intervals in the circumferential direction of the valve seat member 109. The inner seat portion 134 forms an annular shape with the central axis of the valve seat member 109 as the center.

[0086] Inside each valve seat component 201, surrounded by a part of the inner seat portion 134, a passage recess 205 is formed that recesses in the axial direction of the valve seat member 109 from the protruding end surface. The bottom surface of the passage recess 205 is formed by the main body portion 140. A passage recess 205 is formed inside all valve seat components 201.

[0087] A passage hole 206 is formed at the center of the passage recess 205 in the circumferential direction of the valve seat member 109, passing through the main body 140 in the axial direction and thus through the valve seat member 109 in the axial direction. The passage hole 206 is a straight hole parallel to the central axis of the valve seat member 109. The passage hole 206 is formed on the bottom surface of all passage recesses 205.

[0088] The valve seat portion 139 is also a petal-shaped irregular seat. The valve seat portion 139 has multiple valve seat components 211 (only one is shown in Figure 4 due to the cross-sectional view). These valve seat components 211 are the same shape and are arranged at equal intervals in the circumferential direction of the valve seat member 109. The valve seat components 211 are the same shape as the valve seat component 201. The inner seat portion 138 forms an annular shape with the central axis of the valve seat member 109 as the center.

[0089] Inside each valve seat component 211, surrounded by a part of the inner seat portion 138, a passage recess 215 is formed that recesses in the axial direction of the valve seat member 109 from the protruding end surface. The bottom surface of the passage recess 215 is formed by the main body portion 140. A passage recess 215 is formed inside all valve seat components 211.

[0090] A passage hole 216 is formed at the center of the passage recess 215 in the circumferential direction of the valve seat member 109, passing through the main body 140 in the axial direction and thus through the valve seat member 109 in the axial direction. The passage hole 216 is a straight hole parallel to the central axis of the valve seat member 109. The passage hole 216 is formed on the bottom surface of all passage recesses 215.

[0091] The circumferential arrangement pitch of the valve seat members 109 of the multiple valve seat components 201 is the same as the circumferential arrangement pitch of the valve seat members 109 of the multiple valve seat components 211. The valve seat components 201 and 211 are offset from each other by half a pitch. The passage hole 206 is located between adjacent valve seat components 211 in the circumferential direction of the valve seat member 109. Therefore, the passage hole 206 is located outside the range of the valve seat portion 139. The passage hole 216 is located between adjacent valve seat components 201 in the circumferential direction of the valve seat member 109. Therefore, the passage hole 216 is located outside the range of the valve seat portion 135.

[0092] The valve seat member 109 has a passage groove 221 formed on the side of the large-diameter hole 133 in the axial direction, which traverses the inner seat portion 134 radially. The passage groove 221 is formed as a recess in the axial direction of the valve seat member 109 from the end surface of the inner seat portion 134 opposite to the main body portion 140. The passage groove 221 also includes the space between adjacent valve seat components 201 in the circumferential direction of the valve seat member 109. The passage hole 216 opens to the bottom surface of the passage groove 221. The passage groove 221 connects the passage hole 216 to the large-diameter hole 133.

[0093] The passage hole 216 and the passage recess 215 into which the passage hole 216 opens form a first passage portion 161 provided in the valve seat member 109. Multiple first passage portions 161 are provided in the valve seat member 109 at equal intervals in the circumferential direction of the valve seat member 109. The passage groove 221 forms a radial passage 222 extending radially toward the first passage portion 161. Multiple radial passages 222 are provided in the valve seat member 109 at equal intervals in the circumferential direction of the valve seat member 109.

[0094] The valve seat member 109 has a passage groove 225 between adjacent valve seat components 211 in the circumferential direction of the valve seat member 109. The passage hole 206 opens to the bottom surface of the passage groove 225. Therefore, the passage groove 225 communicates with the passage hole 206.

[0095] The passage hole 206 and the passage recess 205 into which the passage hole 206 opens form a second passage portion 162 provided on the valve seat member 109. Multiple second passage portions 162 are provided on the valve seat member 109 at equal intervals in the circumferential direction of the valve seat member 109.

[0096] Multiple first passages 161 and multiple second passages 162 are provided on the valve seat member 109 and constitute a valve seat member passage 160 through which the oil liquid L flows.

[0097] The valve seat member 109 has an annular seal groove 141 formed at the axial midpoint of the outer circumference of the main body portion 140, which is recessed radially inward. An O-ring 108 is positioned within this seal groove 141. The valve seat member 109 is fitted onto the cylindrical portion 124 of the cap member 95 at its outer circumference, with the inner seat portion 138 and the valve seat portion 139 facing away from the bottom portion 122. In this state, the O-ring 108 seals the gap between the cylindrical portion 124 of the cap member 95 and the valve seat member 109.

[0098] The cap member 95, O-ring 108, and valve seat member 109 form a cap chamber 146 inside the cap member 95. The cap chamber 146 is located between the bottom 122 of the cap member 95 and the valve seat member 109. As shown in Figure 5, the discs 97, 102-104, 106, flexible disc 100, valve seat disc 101, spring member 105, sub-valve 107, and disc spring 116 are located within this cap chamber 146.

[0099] Within the cap chamber 146, a lower chamber communication chamber 149 is formed, surrounded by the flexible disc 100, the valve seat disc 101, the disc spring 116, the disc 97, and the bottom portion 122 of the cap member 95. This lower chamber communication chamber 149 is in constant communication with the communication passages 425 within the multiple holes 415 of the disc spring 116 and the communication passages 148 within the multiple passage holes 126 of the bottom portion 122 of the cap member 95.

[0100] Within the cap chamber 146, an upper chamber communication chamber 147 is formed, surrounded by a cap member 95, a disc spring 116, a flexible disc 100, a valve seat disc 101, discs 102-104, 106, a spring member 105, and a sub-valve 107. Communication between the lower chamber communication chamber 149 and the upper chamber communication chamber 147 is blocked by the disc spring 116, the flexible disc 100, and the valve seat disc 101.

[0101] As shown in Figure 4, the annular valve seat member 109 and the bottomed cylindrical cap member 95 are arranged in the lower chamber 23. In this configuration, the valve seat portion 135 of the valve seat member 109 is positioned on the cap chamber 146 side, and the valve seat portion 139 is positioned on the lower chamber 23 side. As shown in Figure 5, the communication passage 148 at the bottom portion 122 of the cap member 95 is in constant communication with the lower chamber 23.

[0102] The upper chamber communication chamber 147 is in constant communication with the upper chamber 22 shown in Figure 4 via the passage between the cylindrical portion 124 of the cap member 95 and the sub-valve 107, the radial passage 222 in the passage groove 221 of the valve seat member 109, the passage in the large diameter hole portion 133 of the valve seat member 109, the rod passage portion 51 in the passage notch portion 30 of the rod 25 and the passage in the large diameter hole portion 46 of the piston 21, the passage in the notch portion 90 of the disc 82, and the passages in the annular groove 55 and the multiple passage holes 38 of the piston 21.

[0103] As the flexible disk 100 flexes in the axial direction, the volumes of the lower chamber communication chamber 149 and the upper chamber communication chamber 147 change. In other words, the flexing of the flexible disk 100 gives the lower chamber communication chamber 149 and the upper chamber communication chamber 147 the function of an accumulator. The lower chamber communication chamber 149 decreases in volume to absorb the increase in volume of the upper chamber communication chamber 147, discharging the oil liquid L into the lower chamber 23, or increases in volume to absorb the decrease in volume of the upper chamber communication chamber 147, allowing the oil liquid L to flow in from the lower chamber 23. Conversely, the upper chamber communication chamber 147 decreases in volume to absorb the increase in volume of the lower chamber communication chamber 149, discharging the oil liquid L to the upper chamber 22 side, or increases in volume to absorb the decrease in volume of the lower chamber communication chamber 149, allowing the oil liquid L to flow in from the upper chamber 22 side. In this manner, the deformation of the flexible disk 100 is suppressed from being inhibited by the oil liquid L in the upper chamber communication chamber 147 and the lower chamber communication chamber 149.

[0104] Multiple passage grooves 225 of the valve seat member 109 are provided facing the lower chamber 23. Multiple second passage sections 162 are in constant communication with the lower chamber 23 via passages within the multiple passage grooves 225. As shown in Figure 5, the communication passage 425 formed in the disc spring 116 and the communication passage 148 formed in the bottom 122 of the cap member 95 are in constant communication with the lower chamber 23, which is one of the upper chamber 22 and the lower chamber 23.

[0105] The radial passage 222 within the passage groove 221 that opens into the first passage portion 161 of the valve seat member 109 is in constant communication with the upper chamber communication chamber 147. The radial passage 222 is in constant communication with the upper chamber communication chamber 147, the passage within the large-diameter hole portion 133 of the valve seat member 109, and the rod passage portion 51 within the passage notch portion 30 of the rod 25.

[0106] As shown in Figure 4, the sub-valve 107 is disc-shaped. The sub-valve 107 has an outer diameter equivalent to the outer diameter of the valve seat portion 135 of the valve seat member 109. The sub-valve 107 is always in contact with the inner seat portion 134 and can seat on and off the valve seat portion 135. By seating on the entire valve seat portion 135, the sub-valve 107 closes all of the second passage portions 162. By seating on the entire valve seat component 201 of the valve seat portion 135, the sub-valve 107 closes the second passage portion 162 inside the valve seat component 201. The spring member 105 causes the sub-valve 107 to come into contact with the valve seat portion 135 of the valve seat member 109. The sub-valve 107 seats on the valve seat portion 135 by the biasing force of the spring member 105 and closes the second passage portion 162.

[0107] A sub-valve 107, which can seat and detach from the valve seat portion 135, is provided in the cap chamber 146. By separating from the valve seat portion 135 within the cap chamber 146, the sub-valve 107 connects the multiple second passage portions 162 with the upper chamber communication chamber 147, thereby connecting the lower chamber 23 with the upper chamber 22. At this time, the sub-valve 107 suppresses the flow of oil liquid L between itself and the valve seat portion 135, generating a damping force. The sub-valve 107 is an inflow valve that opens when oil liquid L flows from the lower chamber 23 to the upper chamber communication chamber 147 side via the multiple second passage portions 162. The sub-valve 107 is a check valve that restricts the outflow of oil liquid L from the upper chamber communication chamber 147 to the lower chamber 23 via the second passage portions 162. Here, the passage hole 216 constituting the first passage portion 161 opens outward from the range of the valve seat portion 135 in the valve seat member 109. Therefore, the passage hole 216 is always in communication with the upper chamber communication chamber 147, independently of the sub-valve 107 seated on the valve seat portion 135.

[0108] The passages within the multiple passage grooves 225, the multiple second passage sections 162, the passage between the sub-valve 107 and valve seat section 135 that appear when the valve is opened, the upper chamber communication chamber 147, the radial passage 222 within the passage groove 221 of the valve seat member 109, the passage within the large-diameter hole section 133 of the valve seat member 109, the rod passage section 51 within the passage notch 30 of the rod 25 and the passage within the large-diameter hole section 46 of the piston 21, the passage within the notch 90 of the disc 82, and the passages within the annular groove 55 of the piston 21 and the multiple passage holes 38 constitute the second passage 172. As the piston 21 moves toward the lower chamber 23, the oil L flows through the second passage 172 from the lower chamber 23, which is the upstream side of the cylinder 4, to the upper chamber 22, which is the downstream side. The second passage 172 is a compression-side passage through which the oil liquid L flows from the lower chamber 23, which is upstream, to the upper chamber 22, which is downstream, during the movement of the piston 21 toward the lower chamber 23, that is, during the compression stroke. The compression-side second passage 172 is provided separately from the compression-side first passage 72.

[0109] The connecting passages 148 and 425 and the lower chamber connecting chamber 149 constitute the contraction-side third passage 511. The third passage 511 is always in communication with the lower chamber 23. The contraction-side third passage 511 is provided separately from the contraction-side second passage 172. The third passage 511 is arranged in parallel with the second passage 172.

[0110] The disc 104 is thicker and more rigid than the sub-valve 107. When the sub-valve 107 deforms, the disc 104 contacts the sub-valve 107 to suppress further deformation of the sub-valve 107. When the flexible disc 100 deforms, the disc 104 contacts the flexible disc 100 to suppress further deformation of the flexible disc 100. The sub-valve 107, the valve seat member 109 including the valve seat portion 135, the cap member 95, the communication passage 148 formed in the cap member 95, the disc spring 116, the discs 97, 102-104, 106 shown in Figure 5, the flexible disc 100, the valve seat disc 101, and the spring member 105 constitute the main body 173 of the compression-side second damping force generating mechanism. The main body 173 of the second damping force generating mechanism is provided in the compression-side second passage 172 shown in Figure 4. The second damping force generating mechanism body 173 opens and closes the second passage 172, thereby suppressing the flow of oil L from the second passage 172 to the upper chamber 22 and generating a damping force.

[0111] The second damping force generating mechanism body 173 is provided on the rod 25. The valve seat portion 135 of the second damping force generating mechanism body 173 is provided on the valve seat member 109. The second damping force generating mechanism body 173 is arranged separately from the first damping force generating mechanism 42, which generates damping force in the same compression stroke. The sub-valve 107 that constitutes the compression-side second damping force generating mechanism body 173 is a compression-side sub-valve. The cap member 95 covers one end face of the second damping force generating mechanism body 173 and the outer circumferential surface of the valve seat member 109. The cap member 95 only needs to cover one end face of the second damping force generating mechanism body 173 and at least a part of the outer circumferential surface of the valve seat member 109.

[0112] As shown in Figure 5, a communication passage 148 is formed at the bottom portion 122 on one axial end of the cap member 95, connecting the inside and outside of the cap member 95. The disc spring 116 is positioned so that one axial end face abuts against the outer circumference of the cap member 95, beyond the communication passage 148. The flexible disc 100 is positioned so as to abut against the other axial end face of the disc spring 116.

[0113] As shown in Figure 4, in the second passage 172, when the second damping force generating mechanism body 173 is in the open state, the passage within the notch 90 of the disc 82 has the narrowest flow path cross-sectional area among the fixed parts, and the flow path cross-sectional area is narrower than on its upstream and downstream sides, forming an orifice 175 in the second passage 172. The orifice 175 is located downstream of the sub-valve 107 in the flow of oil liquid L when the sub-valve 107 is open and oil liquid L flows in the second passage 172. The orifice 175 may also be located upstream of the sub-valve 107 in the flow of oil liquid L when the sub-valve 107 is open and oil liquid L flows in the second passage 172. The orifice 175 is formed by cutting out the disc 82 that contacts the piston 21 in the first damping force generating mechanism 41.

[0114] The compression-side second damping force generating mechanism body 173 does not have a fixed orifice formed in either the valve seat portion 135 or the sub-valve 107 that abuts against it, which would connect the upper chamber 22 and the lower chamber 23 even when they are in contact. In other words, the compression-side second damping force generating mechanism body 173 does not connect the upper chamber 22 and the lower chamber 23 when the valve seat portion 135 and the sub-valve 107 are in contact around their entire circumference. To put it another way, the second passage 172 does not have a fixed orifice formed to constantly connect the upper chamber 22 and the lower chamber 23, and is not a passage that constantly connects the upper chamber 22 and the lower chamber 23.

[0115] The second compression-side passage 172, which connects the upper chamber 22 and the lower chamber 23, is in parallel with the first compression-side passage 72, which also connects the upper chamber 22 and the lower chamber 23. The first damping force generating mechanism 42 is provided in the first passage 72. The second damping force generating mechanism body 173 is provided in the second passage 172. Therefore, the first compression-side damping force generating mechanism 42 and the second damping force generating mechanism body 173 are arranged in parallel.

[0116] As shown in Figure 5, the sub-valve 110 is disc-shaped. The sub-valve 110 has an outer diameter equivalent to the outer diameter of the valve seat portion 139 of the valve seat member 109. The sub-valve 110 is always in contact with the inner seat portion 138 and can seat and detach from the valve seat portion 139. By seating the entire valve seat portion 139, the sub-valve 110 closes all of the first passage portions 161. By seating the entire valve seat component 211 of the valve seat portion 139, the sub-valve 110 closes the first passage portion 161 inside the valve seat component 211. The sub-valve 110 can be interchangeable with the sub-valve 107 by having the same shape.

[0117] Disc 111 has the same shape as disc 106 and is interchangeable. The outer diameter of disc 111 is smaller than the outer diameter of sub-valve 110 and smaller than the outer diameter of inner seat portion 138.

[0118] The spring member 112 has a perforated circular flat base plate portion 341 that fits onto the mounting shaft portion 28, and a plurality of spring plate portions 342 that extend radially outward from the base plate portion 341 at equally spaced positions in the circumferential direction of the base plate portion 341. The outer diameter of the base plate portion 341 is larger than the outer diameter of the disc 111. The spring plate portions 342 are inclined with respect to the base plate portion 341 such that they move further away from the base plate portion 341 in the axial direction of the base plate portion 341 as they extend from the base plate portion 341 toward the sub-valve 110. The base plate portion 341 of the spring member 112 abuts against the disc 111. The plurality of spring plate portions 342 of the spring member 112 abut against the sub-valve 110. The spring member 112 causes the sub-valve 110 to come into contact with the valve seat portion 139 of the valve seat member 109. The sub-valve 110 seats on the valve seat portion 139 due to the biasing force of the spring member 112, thereby closing the first passage portion 161.

[0119] The sub-valve 110 is located in the lower chamber 23. By moving away from the valve seat portion 139, the sub-valve 110 connects the upper chamber 22 and the upper chamber communication chamber 147 with the lower chamber 23. At this time, the sub-valve 110 suppresses the flow of oil L between itself and the valve seat portion 139, thereby generating a damping force. The sub-valve 110 is a discharge valve that opens when the oil L is discharged from the upper chamber 22 and the upper chamber communication chamber 147 to the lower chamber 23 via the multiple first passage portions 161 of the valve seat member 109. The sub-valve 110 is a check valve that restricts the inflow of oil L from the lower chamber 23 into the upper chamber 22 and the upper chamber communication chamber 147 via the first passage portions 161. As shown in Figure 4, the passage holes 206 constituting the second passage portion 162 open outward from the range of the valve seat portion 139 in the valve seat member 109. Therefore, the passage hole 206 is always in communication with the lower chamber 23, independently of the sub-valve 110 seated on the valve seat portion 139.

[0120] The passages within the multiple passage holes 38 and annular groove 55 of the piston 21, the passage within the notch 90 of the disc 82, the rod passage 51 within the passage notch 30 of the rod 25, the passage within the large diameter hole 46 of the piston 21, the passage within the large diameter hole 133 of the valve seat member 109, the radial passage 222 within the passage groove 221 of the valve seat member 109, the multiple first passage portions 161 of the valve seat member 109, and the passage between the sub-valve 110 and valve seat portion 139 that appear when the valve is opened constitute the second passage 182. As the piston 21 moves toward the upper chamber 22, the oil L flows from the upper chamber 22, which is the upstream side of the cylinder 4, toward the lower chamber 23, which is the downstream side, through the second passage 182. The second passage 182 is the extension-side passage through which the oil L flows from the upper chamber 22, which is the upstream side, toward the lower chamber 23, which is the downstream side, during the movement of the piston 21 toward the upper chamber 22, that is, during the extension stroke.

[0121] The second extension passage 182, which connects the upper chamber 22 and the lower chamber 23, runs parallel to the first extension passage 92, which connects the upper chamber 22 and the lower chamber 23, except for the passages within the annular groove 55 on the upper chamber 22 side and the passages within the multiple passage holes 38. The parallel sections of the first passage 92 and the second passage 182 are provided separately from each other.

[0122] The upper chamber communication chamber 147, along with the passage between the cylindrical portion 124 of the cap member 95 and the sub-valve 107, constitutes the extension-side third passage 512. The extension-side third passage 512 branches off from the extension-side second passage 182 and is provided separately from the second passage 182.

[0123] The outer diameter of the disc 113 is the same as the outer diameter of the sub-valve 110. The disc 113 is thicker and more rigid than the sub-valve 110. When the sub-valve 110 deforms, the disc 113 comes into contact with the sub-valve 110, suppressing further deformation of the sub-valve 110. The annular member 114 has a smaller outer diameter than the outer diameter of the disc 113. The annular member 114 is a common part with the same shape as the annular member 69.

[0124] The sub-valve 110, the valve seat member 109 including the valve seat portion 139, the discs 111 and 113, and the spring member 112 constitute the extension-side second damping force generating mechanism body 183. The second damping force generating mechanism body 183 is provided in the extension-side second passage 182. The second damping force generating mechanism body 183 opens and closes the second passage 182, suppressing the flow of oil L from the second passage 182 to the lower chamber 23 and generating damping force. In other words, this second damping force generating mechanism body 183 is provided on the rod 25. The valve seat portion 139 of the second damping force generating mechanism body 183 is provided on the valve seat member 109. The second damping force generating mechanism body 183 is arranged separately from the first damping force generating mechanism 41 which generates damping force in the extension stroke. The sub-valve 110 that constitutes the extension-side second damping force generating mechanism body 183 is an extension-side sub-valve.

[0125] As shown in Figure 5, the flexible disc 100, the valve seat disc 101, the disc spring 116, the disc 97, the bottom portion 122 of the cap member 95, and the lower chamber communication chamber 149 constitute a lower chamber volume variable mechanism 185 that can change the volume of the lower chamber communication chamber 149. The lower chamber volume variable mechanism 185 is provided in the contraction-side third passage 511 which includes the lower chamber communication chamber 149. In the flow path, the lower chamber communication chamber 149 is provided between the flexible disc 100 and the sub-valve 110, via the lower chamber 23 and communication passages 148 and 425.

[0126] The lower chamber volume variable mechanism 185 changes the volume of the lower chamber communication chamber 149 by having the flexible disc 100 and the valve seat disc 101 deform and move together so as to move away from the bottom 122. At that time, if the flexible disc 100 maintains contact with the disc spring 116 around its entire circumference, the space between it and the outer conical portion 403 of the disc spring 116 is closed. In other words, if the flexible disc 100 maintains contact with the disc spring 116 around its entire circumference when it deforms to move away from the bottom 122, the closed state between the lower chamber communication chamber 149 and the upper chamber communication chamber 147 is maintained.

[0127] The lower chamber volume variable mechanism 185 modifies the volume of the lower chamber communication chamber 149 by having the flexible disc 100 and the valve seat disc 101 deform and move together so as to approach the bottom portion 122. At that time, the flexible disc 100 maintains a state in which it is in contact with the disc spring 116 as a whole, and the space between it and the outer conical portion 403 of the disc spring 116 is closed.

[0128] As shown in Figure 4, the extension-side third passage 512, which includes the upper chamber communication chamber 147 communicating with the upper chamber 22, branches off from the extension-side second passage 182 and is provided separately from the second passage 182. As shown in Figure 5, the flexible disc 100, the valve seat disc 101, the disc spring 116, the discs 102-104, the spring member 105, the disc 106, the sub-valve 107, the cap member 95, and the upper chamber communication chamber 147 constitute the upper chamber volume variable mechanism 186, which can change the volume of the upper chamber communication chamber 147. The upper chamber volume variable mechanism 186 is provided in the extension-side third passage 512, which includes the upper chamber communication chamber 147. In the flow path, the upper chamber communication chamber 147 is provided between the flexible disc 100 and the sub-valve 107.

[0129] The upper chamber volume variable mechanism 186 changes the volume of the upper chamber communication chamber 147 by having the flexible disk 100 and the valve seat disk 101 deform and move together so that they move away from disk 104. At that time, if the valve seat disk 101 maintains a state in which it is in contact with the flexible disk 100 as a whole, it closes the communication passage 505 in the communication hole 501 of the flexible disk 100. In other words, it maintains a state of separation between the lower chamber communication chamber 149 and the upper chamber communication chamber 147.

[0130] The upper chamber volume variable mechanism 186 changes the volume of the upper chamber communication chamber 147 by deforming and moving the flexible disk 100 and the valve seat disk 101 so that they move closer to the disk 104. At that time, the valve seat disk 101 maintains a state in which it is in contact with the flexible disk 100 as a whole, closing the communication passage 505 in the communication hole 501 of the flexible disk 100.

[0131] The flexible disc 100, valve seat disc 101, and disc spring 116 are shared between the lower chamber volume variable mechanism 185 and the upper chamber volume variable mechanism 186. The lower chamber volume variable mechanism 185, which includes the lower chamber communication chamber 149, and the upper chamber volume variable mechanism 186, which includes the upper chamber communication chamber 147, constitute an accumulator mechanism 190 that stores oil liquid as the working fluid. The accumulator mechanism 190 is provided on the rod 25. The flexible disc 100 of the accumulator mechanism 190 deforms before the second damping force generating mechanism body 183 opens during the extension stroke, and deforms before the second damping force generating mechanism body 173 opens during the compression stroke.

[0132] The accumulator mechanism 190, together with the extension-side second damping force generating mechanism body 183, constitutes the extension-side second damping force generating mechanism 631 (second force generating mechanism). In other words, the second damping force generating mechanism 631 comprises the second damping force generating mechanism body 183 and the accumulator mechanism 190.

[0133] The accumulator mechanism 190, together with the compression-side second damping force generating mechanism body 173, constitutes the compression-side second damping force generating mechanism 632 (second force generating mechanism). In other words, the second damping force generating mechanism 632 comprises the second damping force generating mechanism body 173 and the accumulator mechanism 190.

[0134] In the second passage 182, when the second damping force generating mechanism body 183 is in the open state, the passage within the notch 90 of the disc 82 has the narrowest flow path cross-sectional area among the fixed parts, and the flow path cross-sectional area is narrower than on its upstream and downstream sides, thus becoming an orifice 175 in the second passage 182 as well. The orifice 175 is common to the second passages 172 and 182. The orifice 175 is located upstream of the sub-valve 110 in the flow of oil liquid L when the sub-valve 110 is open and oil liquid L flows in the second passage 182. The orifice 175 may also be located downstream of the sub-valve 110 in the flow of oil liquid L when the sub-valve 110 is open and oil liquid L flows in the second passage 182. The sub-valve 110 and the sub-valve 107 described above open and close independently.

[0135] The extension-side second damping force generating mechanism body 183 does not have a fixed orifice formed in either the valve seat portion 139 or the sub-valve 110 that abuts against it, which would connect the upper chamber 22 and the lower chamber 23 even when they are in contact. In other words, the extension-side second damping force generating mechanism body 183 does not connect the upper chamber 22 and the lower chamber 23 when the valve seat portion 139 and the sub-valve 110 are in contact around their entire circumference. To put it another way, the second passage 182 does not have a fixed orifice formed to constantly connect the upper chamber 22 and the lower chamber 23, and is not a passage that constantly connects the upper chamber 22 and the lower chamber 23. The annular member 114, together with the disc 113, restricts deformation of the sub-valve 110 in the opening direction beyond a specified limit by abutting against the sub-valve 110.

[0136] The shock absorber 1 allows the oil liquid L to pass through in the axial direction at least within the range of the piston 21, and the upper chamber 22 and lower chamber 23 can communicate only through the first damping force generating mechanisms 41, 42 and the second damping force generating mechanism bodies 173, 183.

[0137] As described above, the second passage 182 and the first passage 92 are parallel to each other, except for the passages within the annular groove 55 and the passages within the multiple passage holes 38. In the parallel section, the first damping force generating mechanism 41 is provided in the first passage 92. The second damping force generating mechanism body 183 is provided in the second passage 182. Therefore, the extension-side first damping force generating mechanism 41 and the second damping force generating mechanism body 183 are arranged in parallel.

[0138] The second damping force generating mechanism bodies 173, 183 include a valve seat member 109, a sub-valve 110 provided on one side of the valve seat member passage portion 160, which is the portion of the second passage 172, 182 provided on the valve seat member 109, and a sub-valve 107 provided on the other side of the valve seat member passage portion 160, and a bottomed cylindrical cap member 95 provided between the piston 21 and the valve seat member 109 in the second passage 172, 182. The valve seat member 109 is provided inside the cap member 95. The sub-valve 110 is provided on the lower chamber 23 side of the valve seat member 109. The sub-valve 107 is provided in the cap chamber 146 between the bottom 122 of the cap member 95 and the valve seat member 109.

[0139] The upper chamber volume variable mechanism 186 of the accumulator mechanism 190 changes the volume of the upper chamber communication chamber 147 by deforming and moving the flexible disk 100 so that it moves away from the disk 104. When the pressure difference between the upper chamber communication chamber 147 and the lower chamber communication chamber 149 exceeds a predetermined value while the second damping force generating mechanism body 183 is open, the flexible disk 100 deforms on its outer circumference toward the bottom 122, while elastically deforming the outer conical portion 403 of the disc spring 116 toward the bottom 122, as shown in Figure 8. As a result, the flexible disk 100 moves axially away from the valve seat disk 101, and connects the upper chamber communication chamber 147 and the lower chamber communication chamber 149 via the communication passage 505 in the communication hole 501. The communication passage 505 within the communication hole 501 and the passage between the flexible disk 100 and the valve seat disk 101 are the fourth passage 521 on the extension side that connects the upper chamber communication chamber 147 and the lower chamber communication chamber 149 during the extension stroke. The fourth passage 521 is provided separately from the third passage 512 which includes the upper chamber communication chamber 147. The fourth passage 521 is provided to communicate in series with the third passage 512 when it is open.

[0140] The flexible disc 100 and the valve seat disc 101 constitute an extension-side relief mechanism 522 that allows oil liquid L to flow from the upper chamber communication chamber 147 to the lower chamber communication chamber 149, or in other words, from the upper chamber 22 to the lower chamber 23, via the fourth passage 521. The relief mechanism 522 is provided in the extension-side fourth passage 521. The relief mechanism 522 is set to open after the extension-side second damping force generating mechanism body 183 opens.

[0141] The upper chamber volume variable mechanism 186 includes a flexible disc 100 that can be bent and a disc spring 116. The flexible disc 100 deforms before the second damping force generating mechanism body 183 opens. The flexible disc 100 has a communication hole 501 that connects the upstream side and the downstream side, between its inner end and outer end. The disc spring 116 contacts the end face of the flexible disc 100 and biases the flexible disc 100. The relief mechanism 522 is arranged so that the communication hole 501 of the flexible disc 100 can be opened and closed depending on the amount of deflection of the flexible disc 100.

[0142] The variable lower chamber volume mechanism 185 of the accumulator mechanism 190 changes the volume of the lower chamber communication chamber 149 by deforming and moving the flexible disc 100 so that it approaches the disc 104. When the pressure difference between the upper chamber communication chamber 147 and the lower chamber communication chamber 149 exceeds a predetermined value while the second damping force generating mechanism body 173 is open, the amount of deformation on the outer circumference of the flexible disc 100 increases, as shown in Figure 9. As a result, the flexible disc 100 moves axially away from the disc spring 116, connecting the lower chamber communication chamber 149 and the upper chamber communication chamber 147 through the disc spring 116. In other words, the portion of the disc spring 116 that abuts the end face of the flexible disc 100 moves at least partially away from the end face of the flexible disc 100 due to the amount of deflection of the flexible disc 100. The passage between the flexible disc 100 and the disc spring 116 is the fourth passage 531 on the compression side, which connects the lower chamber communication chamber 149 and the upper chamber communication chamber 147 during the compression stroke. The fourth passage 531 is provided separately from the third passage 511, which includes the lower chamber communication chamber 149. The fourth passage 531 is provided so as to communicate in series with the third passage 511 when it is open.

[0143] The flexible disc 100 and the disc spring 116 constitute a compression-side relief mechanism 532 that flows oil liquid L from the lower chamber communication chamber 149 to the upper chamber communication chamber 147, or in other words, from the lower chamber 23 to the upper chamber 22, via the fourth passage 531. The relief mechanism 532 is provided in the compression-side fourth passage 531. The relief mechanism 532 is set to open after the compression-side second damping force generating mechanism body 173 opens.

[0144] In its assembled state on the rod 25, the main valve 71 is clamped on its inner circumference by discs 63 and 67, while its outer circumference contacts the valve seat portion 50 of the piston 21 over its entire circumference. In this state, the main valve 91 is clamped on its inner circumference by discs 83 and 87, while its outer circumference contacts the valve seat portion 48 of the piston 21 over its entire circumference.

[0145] In this state, the inner circumference of the sub-valve 107 is clamped between the inner seat portion 134 of the valve seat member 109 and the disc 106, and it abuts against the valve seat portion 135 of the valve seat member 109 all around. In this state, the inner circumference of the sub-valve 110 is clamped between the inner seat portion 138 of the valve seat member 109 and the disc 111, and it abuts against the valve seat portion 139 of the valve seat member 109 all around.

[0146] In this state, as shown in Figure 5, the flexible disc 100 is clamped on its inner circumference by discs 97 and 102 together with the valve seat disc 101, while its outer circumference contacts the outer conical portion 403 of the disc spring 116 over its entire circumference. At this time, the flexible disc 100 elastically deforms in a tapered shape so that the portion radially outside of disc 97 moves further away from the bottom 122 in the axial direction as it moves radially outward. At this time, the disc spring 116's outer conical portion 403 elastically deforms and contacts the flexible disc 100 over its entire circumference. In this state, the valve seat disc 101 also elastically deforms in a tapered shape so that the portion radially outside of disc 102 moves further away from the bottom 122 in the axial direction as it moves radially outward, following the shape of the flexible disc 100.

[0147] As shown in Figure 3, the valve body 12 has fluid passages 251 and 252 that penetrate in the axial direction. Fluid passages 251 and 252 can communicate the lower chamber 23 and the reservoir chamber 5. The base valve 15 has a compression-side damping force generating mechanism 255 on the axial bottom member 9 side of the valve body 12 that can open and close the fluid passage 251. The base valve 15 has an extension-side damping force generating mechanism 256 on the side opposite to the axial bottom member 9 of the valve body 12 that can open and close the fluid passage 252.

[0148] The base valve 15 operates as follows: when the rod 25 moves to the compression side and the piston 21 moves in a direction that narrows the lower chamber 23, causing the pressure in the lower chamber 23 to become higher than a predetermined value than the pressure in the reservoir chamber 5, the damping force generating mechanism 255 opens the fluid passage 251, allowing the oil L from the lower chamber 23 to flow into the reservoir chamber 5, thereby generating damping force. In other words, when the rod 25 moves to the compression side and moves the piston 21, the oil L flows out of the fluid passage 251 into the reservoir chamber 5. The damping force generating mechanism 255 is a damping force generating mechanism for the compression side. This damping force generating mechanism 255 does not obstruct the flow of oil L in the fluid passage 252.

[0149] When the rod 25 moves in the extension direction and the piston 21 moves towards the upper chamber 22, causing the pressure in the lower chamber 23 to drop below the pressure in the reservoir chamber 5, the damping force generating mechanism 256 opens the fluid passage 252, allowing the oil L from the reservoir chamber 5 to flow into the lower chamber 23, thereby generating a damping force. In other words, when the rod 25 moves in the extension direction and moves the piston 21, the oil L flows out of the fluid passage 252 into the lower chamber 23. The damping force generating mechanism 256 is an extension-side damping force generating mechanism. This damping force generating mechanism 256 does not obstruct the flow of oil L in the fluid passage 251. The damping force generating mechanism 256 may also function as a suction valve that flows oil L from the reservoir chamber 5 into the lower chamber 23 without substantially generating a damping force.

[0150] <Operation of shock absorber 1> Hereinafter, the axial movement speed of the rod 25 and piston 21 relative to the cylinder 4 will be referred to as the piston speed.

[0151] As shown in Figure 4, the main valve 91 of the first damping force generating mechanism 41 has higher rigidity and a higher opening pressure than the sub-valve 110 of the second damping force generating mechanism body 183. Therefore, in the extension stroke, in the extremely low-speed region (first speed region) where the piston speed is lower than a predetermined value, the first damping force generating mechanism 41 remains closed while the second damping force generating mechanism body 183 opens. In the normal speed region (second speed region) where the piston speed is above this predetermined value, both the first damping force generating mechanism 41 and the second damping force generating mechanism body 183 open. In other words, the second damping force generating mechanism body 183 of the extension-side second damping force generating mechanism 631 provided in the shock absorber 1 operates in the extension stroke when the piston speed is in the extremely low-speed region (first speed region) while the extension-side first damping force generating mechanism 41, also provided in the shock absorber 1, is not operating. When the piston speed is in the normal speed region (second speed region), which is faster than the extremely low-speed region (first speed region), it operates together with the first damping force generating mechanism 41. The sub-valve 110 is an extremely low-speed valve that opens in the extremely low-speed region of the piston speed to generate damping force.

[0152] In other words, during the extension stroke, the piston 21 moves toward the upper chamber 22, increasing the pressure in the upper chamber 22 and decreasing the pressure in the lower chamber 23. As a result, the oil L in the upper chamber 22 flows into the upper chamber communication chamber 147 via the passages in the multiple passage holes 38 and annular groove 55 of the piston 21, the orifice 175, the passage in the large-diameter hole portion 46 of the piston 21, the rod passage portion 51 in the passage notch 30 of the rod 25 and the passage in the large-diameter hole portion 133 of the valve seat member 109, the radial passage 222 in the passage groove 221 of the valve seat member 109, and the third passage 512. This causes the upper chamber communication chamber 147 to be pressurized. Therefore, before the second damping force generating mechanism body 183 opens, the upper chamber volume variable mechanism 186 causes the portion of the flexible disc 100 radially inward from the contact position with the outer conical portion 403 of the disc spring 116 to bend towards the bottom 122, thereby increasing the volume of the upper chamber communication chamber 147. As a result, the upper chamber volume variable mechanism 186 suppresses the rise in pressure in the upper chamber communication chamber 147. At this time, the valve seat disc 101 deforms in accordance with the flexible disc 100, maintaining the closed state of the fourth passage 521. Also, at this time, as the flexible disc 100 bends and moves towards the bottom 122, the lower chamber volume variable mechanism 185 reduces the volume of the lower chamber communication chamber 149.

[0153] Here, during the extension stroke when the shock absorber 1 is subjected to low-frequency input (large-amplitude excitation), the amount of oil L flowing from the upper chamber 22 to the upper chamber communication chamber 147 becomes large, causing the flexible disc 100 to deform significantly. As the amount of deformation of the flexible disc 100 increases, the reaction force due to the support rigidity on the clamped inner circumference side increases, limiting the amount of deformation. As a result, the upper chamber communication chamber 147 becomes pressurized. Consequently, the second passage 182 becomes pressurized to the point where the second damping force generating mechanism body 183 opens.

[0154] In this case, since neither the second damping force generating mechanism body 173 nor 183 has a fixed orifice that keeps the upper chamber 22 and the lower chamber 23 in constant communication, the damping force rises rapidly during the extension stroke when the piston speed is below the first predetermined value at which the second damping force generating mechanism body 183 opens. Furthermore, in the region where the piston speed is faster than the first predetermined value, and slower than the second predetermined value, the first damping force generating mechanism 41 remains closed while the second damping force generating mechanism body 183 opens.

[0155] In other words, the sub-valve 110 separates from the valve seat portion 139, and the extension-side second passage 182 connects the upper chamber 22 and the lower chamber 23. As a result, the oil L in the upper chamber 22 flows into the lower chamber 23 through the passages in the multiple passage holes 38 and annular groove 55 of the piston 21, the orifice 175, the passage in the large-diameter hole portion 46 of the piston 21, the rod passage portion 51 in the passage notch 30 of the rod 25 and the passage in the large-diameter hole portion 133 of the valve seat member 109, the radial passage 222 in the passage groove 221 of the valve seat member 109, the first passage portion 161 in the valve seat member 109, and the passage between the sub-valve 110 and the valve seat portion 139. This allows the damping force of the valve characteristics (a characteristic in which the damping force is approximately proportional to the piston speed) to be obtained even in the extremely low-speed region where the piston speed is lower than the second predetermined value.

[0156] During the extension stroke, a relief mechanism 522 is provided that opens after the second damping force generating mechanism body 183 opens. Therefore, in the normal speed range where the piston speed is above a second predetermined value, when the pressure in the upper chamber communication chamber 147 increases, the relief mechanism 522 opens the fourth passage 521 while the second damping force generating mechanism body 183 remains open, as shown in Figure 8, allowing the oil L from the upper chamber communication chamber 147 to flow into the lower chamber 23. Subsequently, while the second damping force generating mechanism body 183 and the relief mechanism 522 remain open, the first damping force generating mechanism 41 opens. In other words, as described above, the sub-valve 110 separates from the valve seat portion 139, allowing the oil liquid L to flow from the upper chamber 22 to the lower chamber 23 through the extension-side second passage 182. Then, with the second damping force generating mechanism body 183 remaining open, the relief mechanism 522 opens the fourth passage 521, allowing the oil liquid L to flow from the upper chamber 22 to the lower chamber 23 through the fourth passage 521. At this time, the flow of the oil liquid L is restricted by the orifice 175 located downstream of the main valve 91 in the second passage 182, increasing the pressure applied to the main valve 91 and raising the differential pressure. This causes the main valve 91 to separate from the valve seat portion 48, allowing the oil liquid L to flow from the upper chamber 22 to the lower chamber 23 through the extension-side first passage 92. Therefore, the oil liquid L in the upper chamber 22 flows to the lower chamber 23 through the passages in the multiple passage holes 38 and the annular groove 55, and the passage between the main valve 91 and the valve seat portion 48.

[0157] As a result, even in the normal speed range where the piston speed is above the second predetermined value, a damping force with valve characteristics (where the damping force is approximately proportional to the piston speed) can be obtained. The rate of increase in the extension damping force with respect to an increase in piston speed in the normal speed range is lower than the rate of increase in the extension damping force with respect to an increase in piston speed in the extremely low speed range. In other words, the slope of the rate of increase in the extension damping force with respect to an increase in piston speed in the normal speed range can be made flatter than in the extremely low speed range.

[0158] Here, in the extension stroke, in the normal speed range where the piston speed is above the second predetermined value, the differential pressure between the upper chamber 22 and the lower chamber 23 is greater than in the low-speed range where it is above the first predetermined value but below the second predetermined value. However, since the first passage 92 does not have an orifice for throttling, the main valve 91 opens, allowing the oil liquid L to flow through the first passage 92 at a large flow rate. By throttling the second passage 182 with the orifice 175, and by the relief mechanism 522 opening the fourth passage 521 to allow the oil liquid L from the upper chamber communication chamber 147 to flow into the lower chamber 23, deformation of the sub-valve 110 can be suppressed.

[0159] At this time, the closed sub-valve 107 is subjected to opposing pressures from the lower chamber 23 and the upper chamber communication chamber 147. Even if the pressure difference between the upper chamber 22 and the lower chamber 23 becomes large, the pressure rise in the upper chamber communication chamber 147 is slower than the pressure rise in the upper chamber 22 because the orifice 175 is formed upstream of the sub-valve 107 in the second passage 182. Furthermore, the relief mechanism 522 opens the fourth passage 521, allowing the oil liquid L from the upper chamber communication chamber 147 to flow into the lower chamber 23. This suppresses the increase in the pressure difference between the upper chamber communication chamber 147 and the lower chamber 23. Therefore, it is possible to suppress the increase in the pressure difference between the upper chamber communication chamber 147 and the lower chamber 23 that the closed sub-valve 107 experiences, and to suppress the application of a large back pressure to the sub-valve 107 from the upper chamber communication chamber 147 side to the lower chamber 23 side.

[0160] The buffer 1 has a flow path for the oil liquid L to flow from the upper chamber 22 to the lower chamber 23 during the extension stroke, with a first passage 92 and a second passage 182 arranged in parallel, and a main valve 91 and a sub-valve 110 arranged in parallel. The orifice 175 is connected in series with the sub-valve 110.

[0161] As described above, in the extension stroke, in the normal speed range where the piston speed is above the second predetermined value, the main valve 91 opens, allowing the oil liquid L to flow at a large flow rate through the first passage 92. As a result, the flow rate through the passage between the sub-valve 110 and the valve seat portion 139 is reduced. Therefore, for example, the rate of increase of the damping force with respect to the increase in piston speed in the normal speed range (above the second predetermined value) can be reduced. In other words, the slope of the rate of increase of the extension damping force with respect to the increase in piston speed in the normal speed range (above the second predetermined value) can be made flatter than in the extremely low speed range (below the second predetermined value). This expands the degree of design freedom.

[0162] During the extension stroke when a higher frequency is input to the buffer 1 than during the low-frequency input described above (during small-amplitude excitation), the amount of oil L flowing from the upper chamber 22 to the upper chamber communication chamber 147 is small. As a result, the deformation of the flexible disc 100 is small, and the upper chamber volume variable mechanism 186 can absorb the volume of oil L flowing into the upper chamber communication chamber 147 with the amount of deflection of the flexible disc 100, resulting in a small increase in pressure in the upper chamber communication chamber 147. Therefore, during the rise of the extremely low-speed damping force, it is possible to create a state as if the flexible disc 100 were absent and the upper chamber communication chamber 147 were constantly in communication with the lower chamber 23 through the communication passage 425 of the disc spring 116 and the communication passage 148 of the cap member 95, that is, the same state as a structure without the second damping force generating mechanism body 183.

[0163] Therefore, during the extension stroke at high frequency input, the rise of the extremely low-speed damping force becomes gentler compared to low-frequency input. Or, compared to the conventional damping force characteristics, the rise of the extremely low-speed damping force becomes gentler. In other words, during the extension stroke, when the frequency of the piston 21 exceeds a predetermined frequency, the variable upper chamber volume mechanism 186, which includes the flexible disc 100, limits the flow rate of the oil liquid L to the sub-valve 110 of the second damping force generating mechanism body 183. Furthermore, by changing the rigidity (plate thickness, etc.) of the flexible disc 100, the change in damping force until the valve of the second damping force generating mechanism body 183 opens (the slope of the damping force with respect to piston speed) can be adjusted.

[0164] The main valve 71 of the first damping force generating mechanism 42 has higher rigidity and a higher opening pressure than the sub-valve 107 of the second damping force generating mechanism body 173. Therefore, in the compression stroke, in the extremely low-speed region (first speed region) where the piston speed is lower than a predetermined value, the first damping force generating mechanism 42 remains closed while the second damping force generating mechanism body 173 opens. In the normal speed region (second speed region) where the piston speed is above this predetermined value, both the first damping force generating mechanism 42 and the second damping force generating mechanism body 173 open. In other words, the second damping force generating mechanism body 173 of the compression-side second damping force generating mechanism 632 provided in the shock absorber 1 operates in the compression stroke when the piston speed is in the extremely low-speed region (first speed region) while the compression-side first damping force generating mechanism 42, also provided in the shock absorber 1, is not operating. When the piston speed is in the normal speed region (second speed region), which is faster than the extremely low-speed region (first speed region), it operates together with the first damping force generating mechanism 42. The sub-valve 107 is an extremely low-speed valve that opens in the extremely low-speed region of the piston speed to generate damping force.

[0165] In other words, during the compression stroke, the piston 21 moves towards the lower chamber 23, increasing the pressure in the lower chamber 23 and decreasing the pressure in the upper chamber 22. As a result, the oil L from the lower chamber 23 flows into the lower chamber communication chamber 149 through the communication passage 148 of the cap member 95 and the communication passage 425 of the disc spring 116, into both the first damping force generating mechanisms 41, 42 and the second damping force generating mechanism bodies 173, 183. This causes the lower chamber communication chamber 149 to become pressurized. Therefore, before the second damping force generating mechanism body 173 opens, the flexible disc 100 of the lower chamber volume variable mechanism 185 bends towards the disc 104, increasing the volume of the lower chamber communication chamber 149. This allows the lower chamber volume variable mechanism 185 to suppress the rise in pressure in the lower chamber communication chamber 149. At this time, the valve seat disc 101 deforms in accordance with the flexible disc 100, maintaining the closed state of the fourth passage 521. Furthermore, at this time, as the flexible disk 100 bends and moves toward the disk 104, the upper chamber volume variable mechanism 186 reduces the volume of the upper chamber communication chamber 147.

[0166] During the compression stroke when the shock absorber 1 is subjected to low-frequency input (large-amplitude excitation), the amount of oil L flowing from the lower chamber 23 to the lower chamber communication chamber 149 becomes large. As a result, the flexible disc 100 deforms significantly. When the amount of deformation of the flexible disc 100 becomes large, the reaction force due to the support rigidity on the clamped inner circumference side becomes large, limiting the amount of deformation. This causes the lower chamber communication chamber 149 to become pressurized. Consequently, the second passage 172 becomes pressurized to the point where the second damping force generating mechanism body 173 opens.

[0167] In this case, neither the second damping force generating mechanism body 173 nor 183 has a fixed orifice that keeps the lower chamber 23 and the upper chamber 22 in constant communication. For this reason, during the compression stroke when the piston speed is below the third predetermined value at which the second damping force generating mechanism body 173 opens, the damping force rises rapidly. Also, in the region where the piston speed is faster than the third predetermined value but slower than the fourth predetermined value, the first damping force generating mechanism 42 remains closed while the second damping force generating mechanism body 173 opens.

[0168] In other words, the sub-valve 107 moves away from the valve seat portion 135, and the second passage 172 on the compression side connects the lower chamber 23 and the upper chamber 22. As a result, the oil L in the lower chamber 23 flows to the upper chamber 22 via the second passage portion 162 in the valve seat member 109, the passage between the sub-valve 107 and the valve seat portion 135, the upper chamber connecting chamber 147, the radial passage 222 in the passage groove 221 of the valve seat member 109, the passage in the large diameter hole portion 133 of the valve seat member 109, the rod passage portion 51 in the passage notch portion 30 of the rod 25, the passage in the large diameter hole portion 46 of the piston 21, the orifice 175, and the passages in the multiple passage holes 38 and annular groove 55 of the piston 21.

[0169] Furthermore, a relief mechanism 532 is provided that opens after the second damping force generating mechanism body 173 opens during the compression stroke. Therefore, in the normal speed range where the piston speed is above the fourth predetermined value, when the pressure in the lower chamber communication chamber 149 increases, the relief mechanism 532 opens the fourth passage 531 while the second damping force generating mechanism body 173 remains open, as shown in Figure 9, allowing the oil L from the lower chamber 23 and the lower chamber communication chamber 149 to flow to the upper chamber 22 via the upper chamber communication chamber 147. Subsequently, while the second damping force generating mechanism body 173 and the relief mechanism 532 remain open, the first damping force generating mechanism 42 opens. That is, as described above, the sub-valve 107 separates from the valve seat portion 135, allowing the oil L to flow from the lower chamber 23 to the upper chamber 22 through the compression-side second passage 172. Subsequently, with the second damping force generating mechanism body 173 in the open state, the relief mechanism 532 opens the fourth passage 531, allowing the oil liquid L to flow from the lower chamber 23 to the upper chamber 22 through the fourth passage 531. At this time, the flow of the oil liquid L is restricted in the second passage 172 by the orifice 175 located downstream of the sub-valve 107 and the relief mechanism 532, increasing the pressure applied to the main valve 71 and raising the differential pressure. This causes the main valve 71 to separate from the valve seat portion 50, allowing the oil liquid L to flow from the lower chamber 23 to the upper chamber 22 through the compression-side first passage 72. As a result, the oil liquid L in the lower chamber 23 flows to the upper chamber 22 through the passages in the multiple passage holes 39 and the annular groove 56, and the passage between the main valve 71 and the valve seat portion 50.

[0170] As a result, even in the normal speed range where the piston speed is above the fourth predetermined value, a damping force with valve characteristics (where the damping force is approximately proportional to the piston speed) can be obtained. The rate of increase in compression damping force with respect to an increase in piston speed in the normal speed range is lower than the rate of increase in compression damping force with respect to an increase in piston speed in the extremely low speed range. In other words, the slope of the rate of increase in extension damping force with respect to an increase in piston speed in the normal speed range can be made flatter than in the extremely low speed range.

[0171] Here, in the compression stroke, in the normal speed range where the piston speed is above the fourth predetermined value, the differential pressure between the lower chamber 23 and the upper chamber 22 is greater than in the low-speed range where it is above the third predetermined value and below the fourth predetermined value. However, since the first passage 72 does not have an orifice for throttling, the main valve 71 opens, allowing the oil liquid L to flow through the first passage 72 at a large flow rate. By doing this, along with throttling the second passage 172 with the orifice 175, and by having the relief mechanism 532 open the fourth passage 531, allowing the oil liquid L from the lower chamber 23 and the lower chamber communication chamber 149 to flow into the upper chamber communication chamber 147, deformation of the sub-valve 107 can be suppressed.

[0172] At this time, the sub-valve 110 in the closed state is subjected to pressures in opposite directions from the lower chamber 23 and the upper chamber communication chamber 147. Even if the differential pressure between the lower chamber 23 and the upper chamber 22 becomes large, the orifice 175 is formed downstream of the sub-valve 110 in the second passage 172, and the relief mechanism 532 opens the fourth passage 531, allowing the oil liquid L from the lower chamber 23 and the lower chamber communication chamber 149 to flow into the upper chamber communication chamber 147, thereby suppressing an increase in the pressure difference between the lower chamber 23 and the upper chamber communication chamber 147. Therefore, it is possible to suppress an increase in the pressure difference between the lower chamber 23 and the upper chamber communication chamber 147 that the sub-valve 110 experiences in the closed state, and to suppress a large back pressure being applied to the sub-valve 110 from the lower chamber 23 side to the upper chamber communication chamber 147 side.

[0173] The shock absorber 1 has a flow path for the oil liquid L to flow from the lower chamber 23 to the upper chamber 22 during the compression stroke, with the first passage 72 and the second passage 172 arranged in parallel. The shock absorber 1 also has a main valve 71 and a sub-valve 107 arranged in parallel. The orifice 175 is connected in series with the sub-valve 107.

[0174] As described above, in the compression stroke, in the normal speed range where the piston speed is above the fourth predetermined value, the main valve 71 opens, allowing the oil liquid L to flow at a large flow rate through the first passage 72. As a result, the flow rate through the passage between the sub-valve 107 and the valve seat portion 135 is reduced. Therefore, for example, it is possible to reduce the rate of increase of the damping force with respect to the increase in piston speed in the normal speed range (above the fourth predetermined value). In other words, the slope of the rate of increase of the compression-side damping force with respect to the increase in piston speed in the normal speed range (above the fourth predetermined value) can be made flatter than in the extremely low speed range (below the fourth predetermined value). This expands the degree of design freedom.

[0175] During the compression stroke when a higher frequency is input to the buffer 1 than during the low-frequency input described above (during small-amplitude excitation), the amount of oil L flowing from the lower chamber 23 to the lower chamber communication chamber 149 is small. Therefore, the deformation of the flexible disk 100 is small. Thus, the deformation of the flexible disk 100 is small, and the lower chamber volume variable mechanism 185 can absorb the volume of oil L flowing into the lower chamber communication chamber 149 with the amount of deflection of the flexible disk 100, resulting in a small increase in pressure in the lower chamber communication chamber 149. Therefore, during the rise of the extremely low-speed damping force, it is possible to create a state as if the flexible disk 100 were absent and the lower chamber communication chamber 149 were constantly in communication with the upper chamber communication chamber 147, that is, the same state as a structure without the second damping force generating mechanism body 173.

[0176] Therefore, during the compression stroke at high frequency input, the rise of the extremely low-speed damping force becomes gentler compared to low-frequency input or conventional damping force characteristics. In other words, when the frequency of the piston 21 exceeds a predetermined frequency, the variable lower chamber volume mechanism 185, which includes the flexible disc 100, limits the flow rate of the oil liquid L to the sub-valve 107 of the second damping force generating mechanism body 173. Furthermore, the change in damping force until the valve of the second damping force generating mechanism body 173 opens (the slope of the damping force with respect to the piston speed) can be adjusted by changing the rigidity (plate thickness, etc.) of the flexible disc 100.

[0177] In this case, during the compression stroke, the damping force characteristics are combined with those of the damping force generation mechanism 255.

[0178] Figure 10 is a schematic block diagram showing the configuration of the driving system 650 installed in the vehicle 600 of the embodiment. This driving system 650 is an ADAS (Advanced Driver-Assistance Systems) or AD (Autonomous Driving) system, and is a system that enables autonomous driving (hands-free driving) of the vehicle with the driver taking their hands off the steering wheel. In other words, the driving system 650 can completely automate steering operations and the like on the vehicle 600 side. The driving system 650 assumes such driving as, for example, Level 2 or higher driving as defined by the Society of Automotive Engineers (SAE). Therefore, the vehicle 600 is a vehicle capable of driving at Level 2 or higher as described above, and may be a vehicle capable of partial autonomous driving or a fully autonomous driving vehicle.

[0179] The driving system 650 includes an in-vehicle camera 660, a positioning information receiver 661, a vehicle control device 662, a wireless terminal 663, one or more sensors 664, a navigation device 665, an image display device 666, an audio output device 667, an operation input device 668, a storage device 669, an automatic driving control unit 670, and a vehicle control unit 671. These are connected to communicate via an in-vehicle network compliant with standards such as Controller Area Network (CAN).

[0180] The in-vehicle camera 660 has a two-dimensional detector such as a CCD or C-MOS and an imaging optical system. The in-vehicle camera 660 captures images of the area around the vehicle 600 (for example, the front, side, or rear of the vehicle) and generates an image representing the area around the vehicle 600.

[0181] The positioning information receiver 661 acquires positioning information representing the current position and attitude of the vehicle 600. For example, the positioning information receiver 661 can be a GPS (Global Positioning System) receiver.

[0182] The vehicle control equipment 662 consists of various devices related to vehicle control, including an engine 681 and motor 682 as drive sources for moving the vehicle, a friction brake device 683, a steering device 684, and a transmission (not shown).

[0183] The wireless terminal 663 communicates with other vehicles via vehicle-to-vehicle communication. For example, DSRC (Dedicated Short Range Communications) is used for vehicle-to-vehicle communication. Communication with other surrounding vehicles may be conducted via an external server.

[0184] One or more sensors 664 include sensors for monitoring the surroundings of the vehicle 600, such as lidar (Light Detection and Ranging) and radar sensors.

[0185] The navigation device 665 determines the planned route from the vehicle 600's current location to its destination according to a predetermined route search method, such as Dijkstra's algorithm.

[0186] The image display device 666 is composed of, for example, a liquid crystal display (LCD) and is installed on the exterior panels, windows, etc., of the vehicle 600. The image display device 666 displays the vehicle 600's planned actions when the vehicle 600 is being driven autonomously. The voice output device 667 is installed outside the vehicle 600, similar to the image display device 666, and announces the planned actions audibly to those outside the vehicle. The image display device 666 and the voice output device 667 may be integrated to form an HMI device.

[0187] The operation input device 668 is a device that receives operation information from the driver and consists of buttons, touch sensors, etc. The operation input device 668 receives input from the driver, such as settings to put the vehicle 600 into automatic driving mode.

[0188] The storage device 669, for example, has a hard disk drive or an optical recording medium and an access device thereof, and stores various types of information such as high-resolution maps.

[0189] The automatic driving control unit 670 determines the planned actions of the vehicle 600 while the vehicle is being driven in automatic driving mode. Specifically, the automatic driving control unit 670 applies the position information representing the current position of the vehicle 600 obtained from the positioning information receiver 661 and the planned route to the destination obtained from the navigation device 665 to a high-precision map, and determines the planned actions at merging points, intersections, etc., that exist on the planned route obtained from the high-precision map. Then, the automatic driving control unit 670 adds information from the onboard camera 660 and sensors 664, etc., to create control commands and outputs them to the vehicle control unit 671, which drives the vehicle autonomously.

[0190] The vehicle control unit 671 controls the vehicle control equipment 662 to enable the vehicle 600 to drive autonomously. Based on control commands from the automatic driving control unit 670, the vehicle control unit 671 controls the engine 681 and motor 682, friction brake device 683, steering device 684, transmission (not shown), etc. of the vehicle control equipment 662. For example, the vehicle control unit 671 receives a control command from the automatic driving control unit 670 to determine the steering amount of the steering wheels and controls the steering device 684 so that the steering wheels are turned by this amount.

[0191] Furthermore, the shock absorber 1 is configured such that the second damping force generating mechanism body 183 of the second damping force generating mechanism 631 and the second damping force generating mechanism body 173 of the second damping force generating mechanism 632 operate and generate damping force even when the control command from the automatic driving control unit 670 to the vehicle control unit 671 is in the on-center region. Here, the on-center region is the region from straight-line driving with a steering angle of 0 degrees to a yaw rate (angular velocity) of 1 deg / s generated in the vehicle 600.

[0192] Patent Document 1, mentioned above, discloses a shock absorber installed between the vehicle body and the wheels. However, there is a need to improve the quietness inside the vehicle cabin and to improve the responsiveness of the vehicle's behavior to steering input.

[0193] In the embodiment, the vehicle 600 is provided with a bush 610 that has rigidity to suppress the transmission of high-frequency vibrations of 20 Hz or more transmitted to the wheel 601 to the vehicle body 605. As a result, the vehicle 600 can improve the quietness inside the vehicle cabin.

[0194] Here, if the rigidity of the bush 610 is set to a level that suppresses the transmission of high-frequency vibrations of 20 Hz or more transmitted to the wheel 601 to the vehicle body 605, then while it is possible to improve the quietness inside the vehicle cabin, a delay occurs in the rise of axial force (ground load) due to the deflection of the bush 610 when the suspension structure 602 starts to move. In particular, this may lead to a decrease in the responsiveness of the vehicle behavior to small steering inputs, which are frequent in the normal operating range. In contrast, the vehicle 600 of the embodiment is provided with a shock absorber 1 installed between the vehicle body 605 and the wheel 601. In the extension stroke, the first damping force generating mechanism 41 operates in a state where it is not operating when the piston speed is in the first speed range, and a second damping force generating mechanism 631 operates together with the first damping force generating mechanism 41 when the piston speed is faster than in the second speed range. Furthermore, the shock absorber 1 is provided with a second damping force generating mechanism 632 that operates in the compression stroke when the piston speed is in the first speed range, while the first damping force generating mechanism 42 is not operating, and operates together with the first damping force generating mechanism 42 when the piston speed is higher than the first speed range, in the second speed range. As a result, the vehicle 600 of this embodiment can generate the axial force (ground load) when the suspension structure 602 starts to move using the second damping force generating mechanisms 631 and 632, thereby compensating for the delay in the axial force (ground load) due to the deflection of the bush 610 and improving the responsiveness of the vehicle's behavior to steering input. Thus, the vehicle 600 can suppress the delay in the vehicle's response to steering input, especially during fine steering, which is frequent in the normal operating range and has a particularly significant impact, and improve the responsiveness of the vehicle's behavior to steering input.

[0195] Figure 11 shows the ground contact load of the suspension structure as time from the start of steering. The dashed line X1 in Figure 11 shows the characteristics of the first suspension structure, which has no bushings and no second damping force generating mechanism in the shock absorber. This first suspension structure has a fast rise in ground contact load when starting to move. However, because this first suspension structure has no bushings, the quietness inside the vehicle cabin cannot be improved. The dashed line X2 in Figure 11 shows the characteristics of the second suspension structure, which has bushings with a rigidity higher than the rigidity required to suppress the transmission of high-frequency vibrations of 20 Hz or more transmitted to the wheels to the vehicle body, and no second damping force generating mechanism in the shock absorber. This second suspension structure has a slower rise in ground contact load when starting to move than the first suspension structure. However, this second suspension structure can improve the quietness inside the vehicle cabin compared to the first suspension structure. The dashed line X3 in Figure 11 shows the characteristics of a third suspension structure that has a rigid bushing 610 to suppress the transmission of high-frequency vibrations of 20 Hz or more transmitted to the wheel to the vehicle body, and does not have a second damping force generating mechanism in the shock absorber. In this third suspension structure, the rise of the ground contact load at the start of movement is slower than in the second suspension structure. However, in this third suspension structure, the bushing 610 can improve the quietness inside the vehicle cabin compared to the second suspension structure. The solid line X4 in Figure 11 shows the characteristics of a suspension structure 602 in an embodiment that has a rigid bushing 610 to suppress the transmission of high-frequency vibrations of 20 Hz or more transmitted to the wheel 601 to the vehicle body 605, and the shock absorber 1 has second damping force generating mechanisms 631 and 632. In this suspension structure 602, the rise of the ground contact load at the start of movement is as fast as in the first suspension structure. Also, the quietness inside the vehicle cabin can be improved by the bushing 610, similar to the third suspension structure.

[0196] The vehicle 600 in this embodiment is equipped with a vehicle control unit 671 that receives a control command from the automatic driving control unit 670 to determine the amount of steering of the steering wheels and makes the vehicle 600 drive autonomously. The second damping force generating mechanism body 183 of the second damping force generating mechanism 631 and the second damping force generating mechanism body 173 of the second damping force generating mechanism 632 operate when the steering wheels are turned. This makes it easier to control when making small steering inputs when the vehicle 600 is driven autonomously hands-free, enabling more precise control, such as improved control accuracy for driving on narrow roads or dynamic obstacle avoidance. In other words, generally, the effect of bush deflection is not taken into consideration in control models for autonomous vehicles in order to reduce the computational load. This is because making the physical model complex makes it impossible to issue control commands in real time. Also, if the steering start angle is increased to take into account the effect of bush deflection, the roll of the vehicle increases, leading to a decrease in ride comfort. In contrast, the vehicle 600 of the embodiment can generate the axial force (ground load) when the suspension structure 602 starts moving using the second damping force generating mechanism body 183 of the second damping force generating mechanism 631 and the second damping force generating mechanism body 173 of the second damping force generating mechanism 632. Therefore, without complicating the control of autonomous driving, it is possible to suppress the delay in the vehicle 600's response to steering input, especially during fine steering, which is frequent in the normal operating range and has a particularly significant impact, and to improve the responsiveness of the vehicle 600's behavior to fine steering input. As a result, the vehicle 600 can improve the accuracy of its autonomous driving control during fine steering, which is frequent in the normal operating range. Furthermore, since the vehicle 600 can generate a high damping force from the start of steering using the second damping force generating mechanism body 183 of the second damping force generating mechanism 631 and the second damping force generating mechanism body 173 of the second damping force generating mechanism 632, it is possible to suppress the feeling of roll and suppress the deterioration of ride comfort.

[0197] In the embodiment, the vehicle 600 operates the second damping force generating mechanism body 183 of the second damping force generating mechanism 631 and the second damping force generating mechanism body 173 of the second damping force generating mechanism 632 when the control command from the automatic driving control unit 670 is in the on-center region. Therefore, it is possible to reliably suppress the delay in the vehicle 600's response to steering input, especially during fine steering, which is frequent in the normal operating range and has a particularly significant impact. Here, during automatic driving, the occupants are not driving themselves, so they become highly sensitive to minute vehicle movements (roll), which can cause motion sickness, discomfort, and fatigue. For this reason, there is a great need to improve the accuracy of corrective fine steering, especially during straight-line driving. In response to this, the vehicle 600 can generate a high damping force from the start of steering using the second damping force generating mechanism body 183 of the second damping force generating mechanism 631 and the second damping force generating mechanism body 173 of the second damping force generating mechanism 632, so the feeling of roll can be suppressed, and as a result, motion sickness, discomfort, and fatigue experienced by the occupants can be suppressed.

[0198] In the embodiment of the vehicle 600, since the second damping force generating mechanisms 631 and 632 have an accumulator mechanism 190, it is possible to suppress changes in the force of the shock absorber 1 when the second damping force generating mechanism body 183 of the second damping force generating mechanism 631 and the second damping force generating mechanism body 173 of the second damping force generating mechanism 632 are operating. Therefore, it is possible to further improve ride comfort and suppress the generation of abnormal noises.

[0199] Furthermore, the shock absorber may be the shock absorber 1 described above, with the addition of a damping force adjustment mechanism that is electrically controlled to control the oil L flowing from the upper chamber 22 to the reservoir chamber 5, thereby switching the damping force between hard and soft. If this damping force adjustment mechanism has a pilot valve that is electrically controlled to control the oil L flowing from the upper chamber 22 to the reservoir chamber 5, and a main valve that opens after the pilot valve to control the oil L flowing from the upper chamber 22 to the reservoir chamber 5, then the second damping force generating mechanism body 183 of the second damping force generating mechanism 631 and the second damping force generating mechanism body 173 of the second damping force generating mechanism 632 are set to open at a piston speed lower than the piston speed at which the main valve opens.

[0200] According to the vehicle 600 described above, it is possible to improve the quietness inside the passenger compartment and to improve the responsiveness of the vehicle's behavior to steering input.

[0201] 1... Shock absorber (cylinder device), 4... Cylinder, 25... Rod, 41... First damping force generating mechanism (first force generating mechanism), 42... First damping force generating mechanism (first force generating mechanism), 190... Accumulator mechanism, 600... Vehicle, 601... Wheel, 605... Vehicle body, 610... Bushing (elastic member), 631... Second damping force generating mechanism (second force generating mechanism), 632... Second damping force generating mechanism (second force generating mechanism), 670... Automatic driving control unit, 671... Vehicle control unit.

Claims

A first force generating mechanism is provided in a cylinder device located between the vehicle body and the wheels, and the force generated can be changed by the relative movement of the cylinder and the rod. An elastic member having rigidity is provided between the vehicle body and the wheel, which suppresses the transmission of high-frequency vibrations of 20 Hz or more transmitted to the wheel to the vehicle body side. A second force generating mechanism is provided in the cylinder device, which operates in a first speed range where the movement speed of the rod relative to the cylinder is faster than the first speed range, and operates together with the first force generating mechanism in a second speed range where the movement speed of the rod relative to the cylinder is faster than the first speed range. A vehicle equipped with the following features. 　 The vehicle control unit receives control commands from the automatic driving control unit to determine the amount of steering of the steering wheels and enables the vehicle to drive autonomously. The second force generating mechanism operates when the steering wheel is turned. The vehicle according to claim 1. 　 The second force generation mechanism operates when the control command from the automatic driving control unit is in the on-center region. The vehicle according to claim 2. 　 The second force generation mechanism includes an accumulator mechanism. The vehicle according to claim 1.

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