Shock absorber

Abstract

A shock absorber (10) comprises: fluid chamber forming members (15, 41, 44) that form a fluid chamber (51); a moving member (19) capable of adjusting the position of an elastic member (19) when moved by the pressure of a fluid; and a sealing member (60) that is fixed to the moving member (19) and seals a gap between the fluid chamber (51) and a side surface (15a) of the fluid chamber forming members (15, 41, 44). A recessed relief part is formed on the side surface (15a) of the fluid chamber forming members (15, 41, 44). A discharge hole (73) for discharging the fluid from the fluid chamber (51) is formed in a bottom portion (71) of the relief part (70). A valve-shaped part (62) of the sealing member (60) of the relief part (70) does not come into contact with the bottom portion (71).

Description

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[0001] The present disclosure relates to a shock absorber in which the position of an elastic member can be adjusted by fluid pressure.

[0002] Between the body and wheels of a vehicle, there is a shock absorber that includes a shock absorber body that absorbs impact and a compression coil spring (elastic member) that applies force to the shock absorber body in a direction that extends the length of the shock absorber body when the overall length of the shock absorber body is shortened by an impact. Furthermore, some shock absorbers allow the vehicle height to be adjusted by adjusting the position of a spring bearing that supports the end of the compression coil spring. Prior art related to such a shock absorber is disclosed in Patent Document 1.

[0003] The shock absorber disclosed in Patent Document 1 includes two cylindrical members (fluid chamber forming members) that form a cylindrical jack chamber (fluid chamber) filled with oil as hydraulic fluid, and a jack (moving member) that has a spring bearing that receives a compression coil spring and is movable by the pressure of the oil. The jack can be moved by adjusting the oil pressure in the jack chamber with a hydraulic pump, thereby adjusting the vehicle height.

[0004] JP 2014-69640 A

[0005] The jack is provided with an O-ring as a sealing member that seals the gap between the jack and the side surface of the cylindrical member. A drain hole is formed on the side surface of the cylindrical member to drain oil from the jack chamber. As the jack moves, the O-ring slides to the position where the drain hole is formed, and the O-ring comes into contact with the edge of the drain hole. Furthermore, when oil flows from the jack chamber to the drain hole, a force is also applied to the O-ring that sucks the O-ring into the drain hole. Repeated forward and backward movements of the jack place a load on the O-ring, so there is room for improvement in the sealing member and the drain hole.

[0006] An object of the present disclosure is to provide a shock absorber in which the sealing member has high sealing properties and can have a long life.

[0007] After extensive research, the inventors discovered that it is possible to provide a shock absorber that has high sealing performance and a long service life, the shock absorber including: an elastic member that applies a force to the shock absorber in a direction that extends the shock absorber's overall length; a fluid chamber-forming member that forms a cylindrical fluid chamber filled with fluid; a movable member that moves in response to fluid pressure to adjust the position of the elastic member; a sealing member that has a fixed portion fixed to the movable member and a valve-shaped portion formed integrally with the fixed portion and sliding against the side surface of the fluid chamber-forming member, thereby sealing a gap between the fluid chamber and the side surface of the fluid chamber-forming member; a recessed portion formed in the side surface of the fluid chamber-forming member and having a bottom that does not come into contact with the valve-shaped portion; and a drain hole formed in the bottom of the recessed portion that drains fluid from the fluid chamber when the movable member moves toward the elastic member. The present invention was completed based on these findings.

[0008] According to the present disclosure, there is provided a shock absorber comprising: an elastic member that applies a force to the shock absorber in a direction that extends the overall length of the shock absorber; a fluid chamber forming member that forms a cylindrical fluid chamber that is filled with fluid; a movable member that moves due to the pressure of the fluid to adjust the position of the elastic member; a fixed portion fixed to the movable member and a sealing member that is formed integrally with the fixed portion and has a valve-shaped portion that slides against the side of the fluid chamber forming member, sealing the gap between the fluid chamber and the side of the fluid chamber forming member; a recess that is formed in a recessed shape on the side of the fluid chamber forming member and has a bottom that does not come into contact with the valve-shaped portion; and a discharge hole that is formed at the bottom of the recess that discharges the fluid from the fluid chamber when the movable member moves in a direction approaching the elastic member.

[0009] According to the present disclosure, it is possible to provide a shock absorber in which the sealing member has high sealing performance and can have a long life.

[0010] Fig. 2 is a cross-sectional view of a shock absorber according to an embodiment in which a cross section of the inside of a cylinder is disclosed. Fig. 3 is a schematic diagram of the shock absorber and a vehicle height control device shown in Fig. 1. Fig. 4 is a cross-sectional view of the periphery of the vehicle height control device. Fig. 5 is an enlarged view of a region surrounded by line 4 in Fig. 1. Fig. 6 is a diagram illustrating the angle of the valve-shaped portion of the sealing member, the angle of the connection portion of the discharge hole, and the angle of the opening edge of the discharge hole.

[0011] The embodiment will be described with reference to the accompanying drawings, in which "Up" indicates the top and "Dn" indicates the bottom.

[0012] 1 shows one hydraulic shock absorber 10 (shock absorber) of a pair of hydraulic shock absorbers provided between the body and wheel of a motorcycle, where Up indicates the body side and Dn indicates the axle side.

[0013] The hydraulic shock absorber 10 comprises a shock absorber body 11 that generates a damping force to absorb impact, and a compression coil spring 19 (elastic member) that applies force to the shock absorber body 11 in a direction to extend the length of the shock absorber body 11 whose overall length has been shortened by the impact.

[0014] (Shock absorber body 11) The shock absorber body 11 includes a cylindrical cylinder 12 filled with oil, a piston 13 movable inside the cylinder 12, and a rod 14 to which the piston 13 is fixed and part of which protrudes from the cylinder 12 toward the axle. Note that a well-known shock absorber capable of generating a damping force can be used instead of the shock absorber body 11.

[0015] The opening at the upper end of the cylinder 12 is closed by a cylinder lid 16. A vehicle body side fixing member 17 capable of fixing the shock absorber body 11 to the vehicle body is fixed to the cylinder lid 16 and the upper part of the cylinder 12.

[0016] An axle-side fixing member 18 capable of fixing the hydraulic shock absorber 10 to the axle is provided at the lower end of the rod 14. The axle-side fixing member 18 supports a lower end 19a of a compression coil spring 19. The hydraulic shock absorber 10 may be oriented in either an inverted or upright position.

[0017] (Oil Chambers 21-23) See Figures 1 and 2. The piston 13 divides the interior of the cylinder 12 into a first oil chamber 21 on the vehicle body side and a second oil chamber 22 on the axle side. The cylinder 12 is surrounded by an outer tube 15 that is coaxial with the cylinder 12. The outer tube 15 and the cylinder 12 form a cylindrical third oil chamber 23.

[0018] (Damping force generator 24) The third oil chamber 23 is in communication with the second oil chamber 22. Furthermore, the third oil chamber 23 is in communication with the first oil chamber 21 via the damping force generator 24, which can be operated from the outside. The damping force generator 24 includes a compression-side check valve 25 that opens when the shock absorber body 11 is compressed, and an extension-side check valve 26 that opens when the shock absorber body 11 is extended.

[0019] (Compensation device 27) The damping force generator 24 is in communication with a compensation device 27, which is capable of compensating for a volume of oil equivalent to the volume of the rod 14, via a communication passage 24a. The compensation device 27 includes an oil reservoir chamber 28 for storing oil, an air chamber 29 filled with air, and a bladder 27a that is capable of pressurizing the oil in the oil reservoir chamber 28 by the pressure of the air chamber 29. A description of the specific configurations of the damping force generator 24 and the compensation device 27 will be omitted.

[0020] (Vehicle Height Adjusting Device 30) Please refer to Fig. 3. The hydraulic shock absorber 10 is equipped with a vehicle height adjusting device 30 that can adjust the vehicle height by adjusting the position of a vehicle body side spring bearing portion 32 that can support the upper end portion 19b of the compression coil spring 19.

[0021] The vehicle height adjustment device 30 has a vehicle body side spring bearing portion 32 in one part and is equipped with a cylindrical jack 31 (movable member) that can move in the direction of the axis AX (see Figure 1) of the hydraulic shock absorber 10, and three guide members 41, 44, 47 that can guide the movement of the jack 31.

[0022] (Jack 31) In addition to the vehicle-body-side spring bearing portion 32, the jack 31 includes a base 33 having an inner peripheral surface 34 that is slidable against the outer peripheral surface 15a of the outer tube 15, a vehicle-body-side extension 35 that extends from the base 33 toward the vehicle body, and an axle-side extension 37 that extends from the base 33 toward the axle and has the compression coil spring 19 positioned on its outer periphery. A cover 39 is attached to the tip of the axle-side extension 37 to cover the annular opening between the outer tube 15 and the axle-side extension 37.

[0023] (First guide member 41) The first guide member 41 is a cylindrical member that is fixed to the upper end of the outer tube 15 and can also be considered a part of the outer tube 15. A female thread 15b is formed on the outer peripheral surface of the upper end of the outer tube 15. A female thread 42 that can be fastened to the male thread 15b is formed on the inner peripheral surface of the first guide member 41. The inner peripheral surface 36 of the vehicle body side extension portion 35 is slidable relative to the outer peripheral surface 43 of the first guide member 41.

[0024] (Second guide member 44) The second guide member 44 is a cylindrical member that surrounds the first guide member 41. The upper end of the second guide member 44 is fitted into and fixed to the upper end of the first guide member 41. The outer peripheral surface 35a of the vehicle body side extension portion 35 is slidable relative to the inner peripheral surface 45 of the second guide member 44.

[0025] (Third guide member 47) The third guide member 47 is an annular member located below the first guide member 41 and the second guide member 44. The third guide member 47 is fixed to the outer peripheral surface 15a of the outer tube 15. The inner peripheral surface 38 of the axle-side extension portion 37 is slidable relative to the outer peripheral surface 48 of the third guide member 47.

[0026] (Jack Chamber 51) The area surrounded by the outer tube 15, the first guide member 41, the second guide member 44, the base 33, and the vehicle-side extension 35 forms the jack chamber 51. When the oil pressure in the jack chamber 51 increases, the jack 31 moves in a direction approaching the compression coil spring 19 (toward the axle, downward) (the jack 31 advances).

[0027] (Back pressure chamber 52) The area surrounded by the outer tube 15, the third guide member 47, the base 33, and the vehicle body side extension 35 becomes the back pressure chamber 52. When the oil pressure in the back pressure chamber 52 increases, the jack 31 moves in a direction away from the compression coil spring 19 (toward the vehicle body, upward) (retraction of the jack 31).

[0028] (Hydraulic Pump) Please refer to Figure 2. The operation of the vehicle height control device 30 will be described. The vehicle height control device 30 further has a hydraulic pump 80 that supplies and discharges oil to and from the jack chamber 51. The hydraulic pump 80 has a pump chamber 81 formed inside the hollow rod 14 (see Figure 1) and a hollow pipe 82 that can advance and retreat relative to the pump chamber 81, and performs a pumping operation by expanding and contracting the shock absorber body 11.

[0029] The hydraulic pump 80 further includes a discharge check valve 83 that discharges oil toward the jack 31 , and a suction check valve 84 that draws oil from the cylinder 12 into the pump chamber 81 .

[0030] (Switching Valve) The jack chamber 51 and the oil sump chamber 28 are selectively connected by an electromagnetic switching valve 91. The switching valve 91 opens to stop the oil supplied to the jack chamber 51, or closes to discharge the oil into the oil sump chamber 28.

[0031] (Control Unit) The vehicle height control device 30 includes an ECU 93 that receives a detection signal from the vehicle height detection means 92 and controls the advance and retreat of the solenoid of the switching valve 91 .

[0032] (Sealing member 60) See Figure 3. An annular groove 33a is formed on the inner circumferential surface 34 of the base 33, extending around the entire circumference of the inner circumferential surface 34. A lip packing is provided in the groove 33a as an annular sealing member 60 that seals the gap between the outer circumferential surface 15a of the outer tube 15 and the inner circumferential surface 34 of the base 33. Note that an O-ring, which has a circular cross section and deforms uniformly throughout, is not used as the sealing member 60.

[0033] (Fixed portion 61) Referring to Fig. 4, the seal member 60 has a fixed portion 61 that is fitted into and fixed in the groove 33a. The fixed portion 61 has a shape that matches the shape of the groove 33a.

[0034] (Valve-shaped portion 62) The seal member 60 further has a valve-shaped portion 62 formed integrally with the fixing portion 61. The valve-shaped portion 62 protrudes from a part of the inner circumferential surface 60b of the seal member 60 toward the outer circumferential surface 15a of the outer tube 15. The valve-shaped portion 62 is slidable relative to the outer circumferential surface 15a of the outer tube 15. Note that the inner circumferential surface 60b of the seal member 60 is spaced apart from the outer tube 15 regardless of the position of the jack 31.

[0035] (Relief Portion 70) A recessed relief portion 70 is formed on the outer peripheral surface 15a of the outer tube 15 around the entire circumference of the outer peripheral surface 15a. The relief portion 70 has a bottom portion 71 spaced apart from the valve-shaped portion 62, a vehicle body-side connection portion 72 connecting the bottom portion 71 to the outer peripheral surface 15a, and an axle-side connection portion 75. The connection portions 72, 75 are inclined relative to a direction perpendicular to the bottom portion 71 (the left-right direction in FIG. 4 ). In other words, the distance between the connection portions 72, 75 increases as they extend radially outward (to the right) of the axis. The diameter of the bottom portion 71 is smaller than the diameter of the outer peripheral surface 15a.

[0036] (Drain hole 73) A drain hole 73 is formed in the bottom portion 71 to drain oil from the jack chamber 51 when the jack 31 moves in a direction (downward) approaching the compression coil spring 19. The drain hole 73 communicates with the oil reservoir chamber 28 (see FIG. 2) via the third oil chamber 23 (see FIG. 2).

[0037] (Distal portion 63, proximal portion 64) The following describes the configuration when the valve-shaped portion 62 is located within region R of the relief portion 70 and the tip 60a of the valve-shaped portion 62 is not in contact with the relief portion 70. See Figure 5. The valve-shaped portion 62 has a distal portion 63 on the side away from the compression coil spring 19 (upper side) and a proximal portion 64 on the side closer to the compression coil spring 19 (lower side), with the tip 60a of the valve-shaped portion 62 as the boundary.

[0038] With the direction of the axis AX of the hydraulic shock absorber 10 (vertical direction) as a reference, the inclination of the distal portion 63 with the tip 60a as the base point is defined as a distal portion angle θ1. The inclination of the proximal portion 64 with the tip 60a as the base point is defined as a proximal portion angle θ2. The inclination of the connecting portion 72 is defined as a connecting portion angle θ3. The connecting portion angle θ3 is set smaller than the distal portion angle θ1 and the proximal side angle θ2 (θ3<θ1, θ3<θ2).

[0039] (Opening Edge 74 of Recess 70) The opening edge 74 of the discharge hole 73 formed in the bottom 71 of the recess 70 is chamfered. With respect to the direction of the axis AX of the hydraulic shock absorber 10 as a reference, the chamfering angle θ4 of the opening edge 74 is set to be larger than the connection portion angle θ3, which is the inclination of the connection portion 72.

[0040] Effects of the embodiment The first hydraulic shock absorber 10 (shock absorber) comprises: a compression coil spring 19 (elastic member) that applies force to the shock absorber body 11 in a direction that extends the entire length of the shock absorber body 11; an outer tube 15, a first guide member 41, and a second guide member 44 (fluid chamber forming members) that form a cylindrical jack chamber 51 (fluid chamber) filled with oil (hydraulic oil which is a fluid); a jack 31 (moving member) that moves by the pressure of the oil to adjust the position of the compression coil spring 19; a fixing portion 61 fixed to the moving member; and a sealing member 60 that has a valve-shaped portion 62 that is formed integrally with the fixing portion 61 and slides against an outer peripheral surface 15 a (side surface of the fluid chamber forming member) of the outer tube 15, and that seals a gap between the jack 31 and the outer peripheral surface 15 a (side surface of the fluid chamber forming member). The outer tube 15 has a recessed annular portion 70 formed in the outer peripheral surface 15a thereof and having a bottom 71 spaced apart from the valve-shaped portion 62, and a discharge hole 73 formed in the bottom 71 of the recess 70 for discharging oil from the jack chamber 51 when the jack 31 moves in a direction approaching the compression coil spring 19.

[0041] That is, a so-called lip packing composed of a fixed portion 61 and a valve-shaped portion 62 is used as the sealing member. Compared to an O-ring, a lip packing has higher sealing properties. Therefore, the surface roughness precision of the outer peripheral surface 15a of the outer tube 15, which is the sealing counterpart, can be relaxed, thereby reducing manufacturing costs. Furthermore, the valve-shaped portion 62 of the sealing member 60 does not contact the bottom 71 of the relief portion 70. In particular, when oil is discharged from the jack chamber 51 through the drain hole 73, a flow occurs in which the valve-shaped portion 62 is sucked into the drain hole 73. However, the fixed portion 61 fixes the sealing member 60 to the jack 31, preventing the valve-shaped portion 62 from being sucked into the drain hole 73. Furthermore, damage to the valve-shaped portion 62 due to contact with the opening edge 74 of the drain hole 73 can be suppressed, thereby improving both sealing properties and durability compared to an O-ring. Therefore, the durability of the sealing member 60 is improved. As described above, a hydraulic shock absorber 10 can be provided in which the sealing member 60 has high sealing properties and a long life.

[0042] The second hydraulic shock absorber 10 is the same as the first hydraulic shock absorber 10 in that the fluid chamber forming member includes an outer tube 15, a first guide member 41 (inner cylindrical portion), and the outer tube 15 and first guide member 41 (outer cylindrical portion) surrounding the outer tube 15 and first guide member 41, the space between the outer tube 15 and first guide member 41 is a jack chamber 51 (fluid chamber), the outer peripheral surface 15a of the outer tube 15 (outer peripheral surface of the inner cylindrical portion) is the side of the fluid chamber forming member, and the recess 70 has connecting portions 72, 75 that connect the bottom 71 and the outer peripheral surface, and the connecting portions 72, 75 are inclined with respect to a direction perpendicular to the bottom 71.

[0043] The connecting portion 72 may be, for example, a wall surface perpendicular to the bottom portion 71. In this case, the outer peripheral surface 15a of the outer tube 15 and the connecting portion 72 intersect at right angles to form an angle. Compared to the relief portion 70 that forms such an angle, tilting the connecting portion 72 reduces the load applied to the valve-shaped portion 62 of the seal member 60 that slides relative to the connecting portion 72 when the jack 31 moves. Furthermore, the above configuration is one example of a fluid chamber-forming member, and the number, shape, and other characteristics of the fluid chamber-forming members can be changed as appropriate as long as a cylindrical jack chamber 51 (fluid chamber) is formed.

[0044] The third hydraulic shock absorber 10 is the second hydraulic shock absorber 10, wherein the valve-shaped portion 62 has a distal portion 63 on the side away from the compression coil spring 19 and a proximal portion 64 on the side approaching the compression coil spring 19, with the tip 60a of the valve-shaped portion 62 as the boundary; and when, with the direction of the axis AX of the shock absorber 10 as the reference, the inclination of the distal portion 63 from the tip 60a as the base point is defined as a distal portion angle θ1, the inclination of the proximal portion 64 from the tip 60a as the base point is defined as a proximal portion angle θ2, and the inclination of the connection portion 72 is defined as a connection portion angle θ3, the connection portion angle θ3 is set to be smaller than the distal portion angle θ1 and the proximal portion angle θ2.

[0045] The connection portion angle θ3 may be set larger than the distal portion angle θ1 (θ3 > θ1), but compared to this case, the contact area of ​​the valve-shaped portion 62 with the vehicle body-side connection portion 72 is smaller, thereby reducing the load applied to the valve-shaped portion 62. The inclination of the axle-side connection portion 75 (see FIG. 4) is the same as the inclination of the vehicle body-side connection portion 72, and provides the same effects as those described above. Furthermore, as long as these effects are achieved, the angle of the vehicle body-side connection portion 72 and the angle of the axle-side connection portion 75 may be different from each other.

[0046] In the fourth hydraulic shock absorber 10, in the second hydraulic shock absorber 10, only the distal portion 63 and the proximal portion 64 are able to slide relative to the connecting portion 72. In other words, the inner circumferential surface 60b of the seal member 60 does not slide relative to the outer circumferential surface 15b or the connecting portion 72, thereby improving the durability of the seal member 60.

[0047] The fifth hydraulic shock absorber 10 is different from the second hydraulic shock absorber 10 in that the opening edge 74 of the discharge hole 73 formed in the bottom 71 of the recess 70 is chamfered, and the chamfering angle θ4 of the opening edge 74 is set to be larger than the connection angle θ3, which is the inclination of the connection portion 72, based on the direction of the axis AX of the hydraulic shock absorber 10.

[0048] Since the edge of the opening hole of the discharge hole 73 is chamfered, the flow path area of ​​the oil flowing from the jack chamber 51 to the discharge hole 73 gradually becomes smaller, preventing sudden changes in the oil flow rate and preventing load from being placed on the valve-shaped portion 62.

[0049] It should be noted that the present invention is not limited to the examples provided that the functions and effects of the present invention are achieved.

[0050] DESCRIPTION OF SYMBOLS 10... Hydraulic shock absorber (shock absorber) 11... Shock absorber body 15... Outer tube (fluid chamber forming member) 15a... Outer peripheral surface of outer tube (side surface of fluid chamber forming member) 19... Compression coil spring (elastic member) 31... Jack (moving member) 41... First guide member (fluid chamber forming member) 44... Second guide member (fluid chamber forming member) 51... Jack chamber (fluid chamber) 60... Seal member 61... Fixing portion 62... Valve-shaped portion 63... Distal portion 64... Proximal portion 70... Relief portion 71... Bottom portion 72... Connection portion 73... Discharge hole 74... Opening edge of discharge hole θ1... Distal portion angle θ2... Proximal portion angle θ3... Connection portion angle θ4... Chamfering angle of opening edge AX... Axial direction

Claims

1. A shock absorber, comprising: an elastic member that applies a force to the shock absorber in a direction to extend the overall length of the shock absorber; a fluid chamber forming member that forms a cylindrical fluid chamber filled with fluid; a moving member that moves by the pressure of the fluid and can adjust the position of the elastic member; a fixing portion fixed to the moving member, and a valve-shaped portion integrally formed with the fixing portion and sliding with respect to the side surface of the fluid chamber forming member, the valve-shaped portion being a sealing member that seals a gap between the fluid chamber and the side surface of the fluid chamber forming member; a relief portion formed in a concave shape on the side surface of the fluid chamber forming member and having a bottom portion that the valve-shaped portion does not contact; and a discharge hole formed in the bottom portion of the relief portion, the discharge hole discharging the fluid from the fluid chamber when the moving member moves in a direction approaching the elastic member.

2. According to claim 1, the fluid chamber forming member includes an inner cylinder portion and an outer cylinder portion surrounding the inner cylinder portion, a space between the inner cylinder portion and the outer cylinder portion is the fluid chamber, an outer peripheral surface of the inner cylinder portion is a side surface of the fluid chamber, the relief portion has a connecting portion connecting the bottom portion and the outer peripheral surface of the inner cylinder portion, and the connecting portion is inclined with respect to a direction orthogonal to the bottom portion.

3. According to claim 2, the valve-shaped portion has a distal portion on a side away from the elastic member and a proximal portion on a side approaching the elastic member with a tip of the valve-shaped portion as a boundary. When an inclination of the distal portion with the tip of the valve-shaped portion as a reference point is defined as a distal portion angle, an inclination of the proximal portion with the tip of the valve-shaped portion as a reference point is defined as a proximal portion angle, and an inclination of the connecting portion is defined as a connecting portion angle with respect to a direction of an axis of the shock absorber, the connecting portion angle is set smaller than the distal portion angle and the proximal portion angle.

4. According to claim 3, only the distal portion and the proximal portion are slidable with respect to the connecting portion.

5. According to claim 2, an opening edge of the discharge hole formed in the bottom portion of the relief portion is chamfered, and an angle of the chamfer of the opening edge is set larger than a connecting portion angle which is an inclination of the connecting portion with respect to a direction of an axis of the shock absorber.

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