Buffer

Abstract

To provide a buffer capable of suppressing deterioration of assembling performance caused by an increase in the size of a baffle plate.SOLUTION: By providing a lightened part 41 on the outer side of a partition wall upper part 38, the volume of the partition wall upper part 38 is set equivalent to that of a partition wall upper part in a conventional baffle plate. This structure can suppress an increase in elastic reaction force of a partition wall part 37 in centering of an outer cylinder relative to a cylinder 2 to which a separator tube 20 is mounted when a rod guide 8 is attached, so as to make attachment load (elastic reaction force) equivalent to that of a conventional buffer, and can secure assembling performance of a buffer 1 without deteriorating performance of a baffle plate 31.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a damping force adjustable shock absorber that controls the flow of the working fluid generated by the stroke of the piston rod to adjust the damping force.

Background Art

[0002] Patent Document 1 discloses a control valve side-mounted type damping force adjustable hydraulic shock absorber (hereinafter referred to as "conventional shock absorber") including a baffle plate that controls the flow of the working fluid flowing from an opening provided in the side wall of the outer cylinder to the reservoir through a damping force adjustment mechanism.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Here, in the conventional shock absorber, by configuring the damping force adjustment mechanism (main body) to be connected to the separator tube (intermediate cylinder) without providing a connecting member, the axial length of the valve mechanism portion can be shortened and the damping force adjustment mechanism can be miniaturized. In this case, the aperture diameter of the opening formed in the outer tube becomes large, and accordingly, the baffle plate becomes large. When aligning the cylinder with respect to the outer cylinder during the assembly of the rod guide, the partition wall portion of the baffle plate is pressurized (compressed) between the outer tube and the separator tube attached to the cylinder. However, due to the increase in the elastic reaction force (assembly load) of the partition wall portion of the enlarged baffle plate, alignment becomes difficult and the assemblability deteriorates.

[0005] An object of the present invention is to provide a shock absorber capable of suppressing a decrease in assemblability due to an increase in the size of the baffle plate.

Means for Solving the Problems

[0006] The shock absorber of the present invention includes a cylinder in which a working fluid is enclosed, a piston slidably inserted into the cylinder and partitioning the inside of the cylinder into a cylinder upper chamber and a cylinder lower chamber, a piston rod having one end connected to the piston and the other end extending to the outside of the cylinder, an outer cylinder provided on the outer periphery of the cylinder, a reservoir formed between the cylinder and the outer cylinder, an intermediate cylinder provided on the outer periphery of the cylinder and having both ends fitted to the cylinder, an annular flow path formed between the cylinder and the intermediate cylinder, a communication path provided on the side wall of the cylinder and communicating the cylinder upper chamber and the annular flow path, a connection pipe provided on the side wall of the intermediate cylinder, an opening provided on the side wall of the outer cylinder and opening at a position facing the connection pipe, a damping force adjustment mechanism connected to the connection pipe, and a partition member provided in the reservoir and having a partition portion for controlling the flow direction of the working fluid flowing from the cylinder upper chamber, through the communication path, the annular flow path, the damping force adjustment mechanism, and into the reservoir from the opening. The partition portion includes an upper partition portion located above the center of the connection pipe and extending in an arc shape in a front view, and a pair of lower partition portions extending downward from both ends of the upper partition portion. The upper partition portion has a groove formed on the inner side, an upper end portion protruding outward, an outer surface inclined from the upper end portion, and an R portion formed between the upper end portion and the outer surface. and the lower part of the partition wall has a notch for adjusting the rigidity of the partition wall portion It is characterized by the above.

Effect of the Invention

[0007] According to the present invention, it is possible to suppress a decrease in the assemblability of the shock absorber due to an increase in the size of the baffle plate.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Mode for Carrying Out the Invention

[0009] An embodiment of the present invention will be described with reference to the attached drawings. As shown in FIG. 1, the shock absorber 1 according to this embodiment is a so-called control valve side-mounted type damping force adjustable hydraulic shock absorber in which the damping force adjustment mechanism 30 is mounted horizontally on the side wall of the outer tube 3 (outer cylinder). The shock absorber 1 is arranged vertically on the vehicle. In the following description, the vertical direction in FIG. 1 is referred to as the vertical direction in the shock absorber 1. Also, for convenience, the left side in FIG. 2 (the side where the cylinder 2 is arranged) is referred to as one side, and the right side in FIG. 2 (the side opposite to the side where the cylinder 2 is arranged) is referred to as the other side.

[0010] The shock absorber 1 has a double-cylinder structure in which a cylinder 2 is provided inside the outer tube 3. A reservoir 4 is formed between the outer tube 3 and the cylinder 2. Inside the cylinder 2, a piston 5 that partitions the inside of the cylinder 2 into a cylinder upper chamber 2A and a cylinder lower chamber 2B is slidably inserted. The lower end of a piston rod 6 is connected to the piston 5. The upper end side of the piston rod 6 passes through the cylinder upper chamber 2A, is inserted through a rod guide 8 and an oil seal 9 attached to the upper ends of the cylinder 2 and the outer tube 3, and protrudes outside the cylinder 2.

[0011] The piston 5 is provided with an extending-side passage 11 and a contracting-side passage 12 that communicate the upper cylinder chamber 2A and the lower cylinder chamber 2B. The contracting-side passage 12 is provided with a disk valve 13 (check valve) that allows the flow of the working fluid from the lower cylinder chamber 2B to the upper cylinder chamber 2A. On the other hand, the extending-side passage 11 is provided with a disk valve 14 (pressure regulating valve) that opens when the pressure on the upper cylinder chamber 2A side reaches the set pressure and releases the pressure on the upper cylinder chamber 2A side to the lower cylinder chamber 2B side.

[0012] At the lower end of the cylinder 2, a base valve 10 that partitions the lower cylinder chamber 2B and the reservoir 4 is provided. The base valve 10 is provided with an extending-side passage 15 and a contracting-side passage 16 that communicate the lower cylinder chamber 2B and the reservoir 4. The extending-side passage 15 is provided with a disk valve 17 (check valve) that allows the flow of the working fluid from the reservoir 4 side to the lower cylinder chamber 2B side. On the other hand, the contracting-side passage 16 is provided with a disk valve 18 (pressure regulating valve) that opens when the pressure on the lower cylinder chamber 2B side reaches the set pressure and releases the pressure on the lower cylinder chamber 2B side to the reservoir 4 side. Note that the working fluid is enclosed in the cylinder 2, and the working fluid and gas are enclosed in the reservoir 4.

[0013] Both ends of a separator tube 20 (intermediate cylinder) are slidably fitted to the outer periphery of the cylinder 2 via a pair of upper and lower seal members 19, 19. An annular flow path 21 is formed between the cylinder 2 and the separator tube 20. The annular flow path 21 communicates with the upper cylinder chamber 2A through a communication passage 22 provided in the side wall of the cylinder 2. A cylindrical connection tube 23 that protrudes laterally and has an open tip is provided at the lower end side of the side wall of the separator tube 20. An opening 24 that faces the connection tube 23 is provided in the side wall of the outer tube 3. A substantially cylindrical valve case 25 that is coaxially arranged with the opening 24 is provided in the side wall of the outer tube 3. A damping force adjustment mechanism 30 is housed in the valve case 25. The inner diameter of the valve case 25 and the hole diameter of the opening 24 are set to be the same.

[0014] As shown in FIG. 2, the damping force adjustment mechanism 30 has a back pressure type main valve 51 that generates a damping force. An annular packing 60 (elastic sealing member) is joined to the outer peripheral edge of the back surface (the other side surface) of the main valve 51. The damping force adjustment mechanism 30 further includes a main body 52 with which the main valve 51 abuts, a back pressure chamber 72 formed on the back of the main valve 51 and in which the internal pressure acts on the main valve 51 in the valve closing direction, a pilot case 73 that forms the back pressure chamber 72, a pilot valve 71 that adjusts the internal pressure of the back pressure chamber 72 to control the opening pressure of the main valve 51, a pilot body 74 against which the pilot valve 71 abuts, a fail-safe valve 111 provided on the downstream side of the pilot valve 71, and a solenoid 121 that controls the opening pressure of the pilot valve 71.

[0015] An annular seat portion 53 is provided at the outer peripheral edge of the other end surface of the main body 52, against which the outer peripheral edge of the main valve 51 can abut and separate. An annular recess 55 is formed on the inner peripheral side (upstream side of the main valve 51) of the seat portion 53. A connection portion 65 that fits (is inserted) into the connection pipe 23 of the separator tube 20 is formed at the center of one end surface of the main body 52. The connection between the connection portion 65 of the main body 52 and the connection pipe 23 of the separator tube 20 is sealed by a seal ring 58.

[0016] A recess 66 with a regular hexagonal cross section that opens into the annular flow path 21 is provided on one end surface of the connection portion 65 of the main body 52. The main body 52 has a plurality of (six in the second embodiment) passages 67 that communicate the recess 66 and the annular recess 55. A pin portion 85 that is inserted into the shaft hole 105 of the pilot case 73 is provided at the center of the other end surface of the main body 52. A passage 93 that is coaxially arranged with the axis of the solenoid 121 opens on the other end surface of the pin portion 85. The passage 93 communicates with the annular flow path 21 via a recess 66 and an introduction orifice 94 provided in the main body 52.

[0017] Between the inner peripheral portion 54 of the main body 52 and the inner peripheral portion 76 of the pilot case 73, a main valve 51, a retainer and a spacer (reference numerals omitted), and a back pressure introduction valve 81 are interposed. The tip (the other side) of the pin portion 85 projects into a small inner diameter portion 91 provided at the bottom of a large inner diameter portion 90 that opens to the other side end face of the pilot case 73. Then, by tightening a nut 87 screwed onto a thread portion (reference numerals omitted) formed at the tip of the pin portion 85, axial force is applied to an annular member interposed between the inner peripheral portion 54 of the main body 52 and the inner peripheral portion 76 of the pilot case 73, and the main body 52 and the pilot case 73 are integrated. When tightening the nut 87, a hexagon wrench is engaged with the recess 66 (hexagonal hole).

[0018] An annular recess 77 is provided on the outer peripheral side of one side end face of the pilot case 73. The annular recess 77 has an inner cylindrical surface 78 against which the packing 60 of the main valve 51 is slidably abutted. An annular seat portion 79 is formed at the inner peripheral edge of the annular recess 77. The outer peripheral edge portion of the back pressure introduction valve 81 is detachably seated and abutted against the seat portion 79. An annular recess 80 is formed on the inner peripheral side of the seat portion 79. The annular recess 80 communicates with the space inside the small inner diameter portion 91 through a plurality of (only "two" are shown in FIG. 2) passages 92. Note that a plurality of orifices (reference numerals omitted) for communicating the back pressure chamber 72 with the annular flow path 21 are provided at the outer peripheral edge portion of the back pressure introduction valve 81.

[0019] The pilot body 74 is formed in a substantially bottomed cylindrical shape with the other side open. One side of the pilot body 74 is fitted into the large inner diameter portion 90 of the pilot case 73. The pilot body 74 is axially positioned with respect to the pilot case 73 by being abutted against an annular surface 96 (step portion) formed between the large inner diameter portion 90 and the small inner diameter portion 91 of the pilot case 73. Note that the space between the pilot case 73 and the pilot body 74 is sealed by a seal ring 98.

[0020] Inside the pilot body 74, a valve chamber 100 for accommodating a pilot valve 71 and a fail-safe valve 111 is provided. In the valve chamber 100, hydraulic fluid is introduced from the annular flow path 21 through an introduction orifice 94, a passage 93 formed in the pilot case 73, and a passage 101 formed at the center of the bottom of the pilot body 74. At the peripheral edge of the other-side opening of the passage 101 in the pilot body 74, a seat portion 102 is provided against which the valve element 103 of the pilot valve 71 can abut and separate. The valve element 103 is formed in a substantially cylindrical shape, and one-side end portion is formed in a tapered shape. On the other side of the valve element 103, an outer flange-shaped spring receiving portion 104 is provided. The valve element 103 is biased in the valve-opening direction (the other-side direction) by a return spring 112 (non-linear spring) that integrates a pilot spring and a fail-safe spring.

[0021] Inside the other-side opening of the pilot body 74, the return spring 112, a spacer and a retainer (reference numeral omitted), and a washer 110 are laminated. These laminated components are fixed to the pilot body 74 by a cap 115 attached to the outer periphery of the other side of the pilot body 74. In the cap 115, a notch 116 (communication passage) for communicating the valve chamber 100 with an annular flow path 117 formed on the outer periphery of the cap 115 is formed. The valve chamber 100 communicates with the reservoir 4 through the notch 116 formed in the cap 115, the flow path 117 formed on the outer periphery of the cap 115, a passage 118 formed between the two-side width 89 of the pilot case 73 (only one side is shown in FIG. 2) and the cylindrical portion 123 of the yoke 122, and an annular flow path 26 formed on the outer periphery of the main valve 51.

[0022] Note that the pilot case 73 and the yoke 122 are fastened by a fastening portion 124 formed by screwing a screw portion (male screw) formed on the pilot case 73 into a screw portion (female screw) formed on the cylindrical portion 123 of the yoke 122. Thereby, an axial force is applied to the pilot body 74, the return spring 112, the spacer, the retainer, the washer 110, and the cap 115 provided between the pilot case 73 and the yoke 122. Here, when fastening the pilot case 73 and the yoke 122, a tool is engaged with a two-sided width 89 formed on the pilot case 73 and a two-sided width 138 formed on the yoke 122.

[0023] On the other side of the yoke 122, a coil 126, a core 127, a fixed core 128, a movable core 129, and a hollow operating rod 130 are assembled. Note that the operating rod 130 is configured integrally with the movable core 129, but may be configured separately. A valve body 103 of the pilot valve 71 is fixed to one end portion of the operating rod 130. A spacer 131 and a cover 132 are inserted into the other end portion of the yoke 122, and by plastically working (crimping) the other opening of the yoke 122, an axial force is applied to the solenoid internal components in the yoke 122.

[0024] The cylindrical portion 123 of the yoke 122 is fitted into the other opening of the valve case 25. The yoke 122 is positioned axially by abutting against a stepped portion 27 of the valve case 25. The space between the yoke 122 and the valve case 25 is sealed by a seal ring 134. The yoke 122 is fixed to the valve case 25 by tightening a nut 135 screwed onto the valve case 25 to compress a retaining ring 137.

[0025] When the coil 126 is de-energized, the valve body 103 is biased in the off-seat direction (the other side direction) by the spring force of the return spring 112. Thereby, the spring receiving portion 104 of the valve body 103 abuts (seats) against the fail-safe disk 113, and the fail-safe valve 111 is closed.

[0026] On the other hand, when the coil 126 is energized, the actuating rod 130 is biased in the seating direction (one-side direction) of the valve body 103 by the thrust of the movable iron core 129. As a result, the actuating rod 130 propels against the spring force of the return spring 112, and the valve body 103 is seated on the seat portion 102. Here, the opening pressure of the valve body 103 is controlled by the current value applied to the coil 126. In the soft mode where the current value applied to the coil 126 is small, the spring force of the return spring 112 and the thrust of the movable iron core 129 (actuating rod 130) are balanced, and the valve body 103 is kept in a state of being separated from the seat portion 102 by a certain distance (see FIG. 2).

[0027] Next, the baffle plate 31 (partition member) will be described. As shown in FIG. 2, the baffle plate 31 is provided in the reservoir 4 so as to face the opening 24. The baffle plate 31 controls the flow direction of the working fluid flowing from the flow path 26 of the damping force adjusting mechanism 30 through the opening 24 into the reservoir 4, and suppresses the aeration generated by the agitation of the working fluid and the gas in the reservoir 4.

[0028] The baffle plate 31 is attached to the outer periphery of the separator tube 20 (intermediate cylinder) and is curved in an arc shape along the outer peripheral surface 28 (curved surface) of the separator tube 20. As shown in FIGS. 3 to 5, the baffle plate 31 has a thin plate-shaped base portion 32 and a partition portion 37 provided at the edge of the base portion 32 excluding the lower end edge (lower side edge). The partition portion 37 projects from the edge of the base portion 32 to the other side ("right side" in FIG. 4), and the tip portion is brought into contact with the inner peripheral surface 7 of the outer tube 3.

[0029] The base 32 is formed such that, when viewed from the front (see Fig. 3), the upper part is substantially semi-circular and the lower part is rectangular. On the back surface 33 of the base 32, two seats 34, 34 (see Fig. 5) that abut against the reduced-diameter portion 29 of the separator tube 20 are provided at intervals in the circumferential direction. In the center of the base 32, a connection port 35 that protrudes to the other side is provided. The connection port 35 is fitted with a certain tightening allowance to the outer circumference of the connection tube 23 of the separator tube 20. Note that the baffle plate 31 of the present embodiment is an integrally molded product of a single material and is composed of an elastic body having flexibility such as NBR (nitrile rubber), but metal or plastic can be used as the material of the base 32.

[0030] Here, the upper part of the partition wall portion 37 above the center of the connection port 35 (the part located above the connection tube 23), that is, the semi-circular arch-shaped part above the line segment B-B in Fig. 3 when viewed from the front, is referred to as the upper partition wall 38.

[0031] As shown in Fig. 6, the upper partition wall 38 has a cross-section formed by the axial plane of the connection tube 23 being a right triangle. The upper partition wall 38 has an inner surface 39 provided perpendicular to the base 32 and facing the opening 24 (see Fig. 2) of the outer tube 3, and an outer surface 40 (corresponding to the hypotenuse of the right triangle) formed on the back of the inner surface 39. A groove 36 that is recessed toward the back surface 33 side of the base 32 (the "left side" in Fig. 6) is provided at the ridge portion between the inner surface 39 and the base 32. Note that the groove 36 is provided over the entire length of the partition wall portion 37 and acts such that the partition wall portion 37 falls inward when the partition wall portion 37 is pressed between the outer tube 3 and the separator tube 20.

[0032] Here, the dashed line 42 in Fig. 6 indicates the outer surface of the baffle plate in a conventional shock absorber, in other words, the outer surface of the baffle plate (hereinafter referred to as the "conventional baffle plate") in a conventional shock absorber where the aperture diameter of the opening of the outer tube is smaller than the inner diameter of the valve case. As shown in Fig. 6, the baffle plate 31 has a cutout in the hatched portion between the dashed line 42 and the outer surface 40. For the sake of convenience, the hatched portion is referred to as the cutout portion 41. In the present embodiment, the cutout portion 41 is provided outside the upper partition wall 38.

[0033] The tip angle θ1 of the upper partition 38 in the baffle plate 31, that is, the angle θ1 formed by the inner surface 39 and the outer surface 40 of the upper partition 38, is set to be less than 50 degrees, and is 40 degrees in this embodiment. On the other hand, the tip angle θ2 of the upper partition in the conventional baffle plate, that is, the angle θ2 formed by the inner surface and the outer surface of the upper partition, is generally 50 degrees or more, for example, 54 degrees. Note that the tip angle θ1 of the upper partition 38 is not limited to 40 degrees, and by adjusting the tip angle θ1 within a range where the function as the baffle plate 31 is not impaired, the amount of thinning of the upper partition 38 by the thinning portion 41, and thus the volume of the upper partition 38, is adjusted.

[0034] In this embodiment, by the tip angle θ1, the volume of the upper partition 38 is adjusted to be equivalent to the volume of the upper partition in the conventional baffle plate, so as to control the deformation (assembly load) of the upper partition 38 when the upper partition 38 is pressed between the outer tube 3 and the separator tube 20 during assembly. Note that an R portion 43 (outer R) is formed at the tip portion of the upper partition 38, that is, at the ridge portion between the inner surface 39 and the outer surface 40. Also, a portion of the upper end portion 44 of the base portion 32 projects above (outside) the upper partition 38. Further, an R portion 45 (inner R) is formed between the upper partition 38 and the upper end portion 44 of the base portion 32.

[0035] On the other hand, the partition portion 37 has lower partitions 46, 46 that extend downward along both end edges of the base portion 32 (the left and right side edges in FIG. 3) from both ends of the upper partition 38. The lower partitions 46, 46 have the same cross-sectional shape (see FIG. 6) as the upper partition 38, so as to be smoothly continuous with the upper partition 38. Note that the tip angles of the lower partitions 46, 46 are set to be the same as the tip angle θ1 of the upper partition 38. Also, no projecting portion like the upper end portion 44 is formed outside the lower partitions 46, 46.

[0036] Next, the operation of the shock absorber 1 will be described. The buffer 1 is vertically provided between the above-spring (vehicle body) and the below-spring (wheel) of a suspension device (not shown) of a vehicle. In a normal operating state, an in-vehicle controller (not shown) adjusts the opening pressure of the pilot valve 71 by controlling the energizing current to the coil 126 of the solenoid 121 of the damping force adjustment mechanism 30.

[0037] During the extension stroke of the piston rod 6, the disk valve 13 of the piston 5 closes due to the pressure increase in the upper cylinder chamber 2A, and the working fluid on the upper cylinder chamber 2A side is pressurized before the disk valve 14 opens. Thereby, the working fluid is introduced into the damping force adjustment mechanism 30 through the communication passage 22, the annular flow passage 21, and the connecting pipe 23. At this time, the working fluid corresponding to the movement of the piston 5 opens the disk valve 17 of the base valve 10 and flows from the reservoir 4 to the lower cylinder chamber 2B. When the pressure in the upper cylinder chamber 2A reaches the opening pressure of the disk valve 14 of the piston 5 and the disk valve 14 opens, the pressure in the upper cylinder chamber 2A is relieved to the lower cylinder chamber 2B, and an excessive pressure increase in the upper cylinder chamber 2A is avoided.

[0038] On the other hand, during the compression stroke of the piston rod 6, the disk valve 13 of the piston 5 opens due to the pressure increase in the lower cylinder chamber 2B, and the disk valve 17 of the passage 15 of the base valve 10 closes. Before the disk valve 18 opens, the working fluid flows from the lower piston chamber 2B to the upper cylinder chamber 2A. At this time, the working fluid corresponding to the volume of the piston rod 6 entering the cylinder 2 is introduced into the damping force adjustment mechanism 30 from the upper cylinder chamber 2A through the communication passage 22, the annular flow passage 21, and the connecting pipe 23. When the pressure in the lower cylinder chamber 2B reaches the opening pressure of the disk valve 18 of the base valve 10 and the disk valve 18 opens, the pressure in the lower cylinder chamber 2B is relieved to the reservoir 4, and an excessive pressure increase in the lower cylinder chamber 2B is avoided.

[0039] The working fluid introduced into the damping force adjustment mechanism 30 is introduced into the annular recess 80 through the introduction orifice 94, the passage 93 provided in the main body 52, the small inner diameter portion 91 of the pilot case 73, and the passage 92 provided in the pilot case 73. Here, when the pressure in the annular recess 80 reaches the valve opening pressure of the back pressure introduction valve 81, the back pressure introduction valve 81 opens, and the working fluid is introduced into the back pressure chamber 72.

[0040] And before the main valve 51 opens (in the low piston speed range), when the pressure upstream of the pilot valve 71 reaches the valve opening pressure of the valve body 103, the pilot valve 71 (valve body 103) opens, and the working fluid passes through the introduction orifice 94, the passage 93, the small inner diameter portion 91, and the passage 101 provided in the pilot case 73 and is introduced into the valve chamber 100 in the pilot body 74.

[0041] The working fluid introduced into the valve chamber 100 flows from the opening 24 formed in the outer tube 3 to the reservoir 4 through the notch 116 of the cap 115, the flow path 117 on the outer periphery of the cap 115, the passage 118, and the flow path 26 on the outer periphery of the main valve 51. Then, as the piston speed increases and the pressure upstream of the main valve 51, that is, the pressure in the annular recess 55 communicated with the annular flow path 21 through the plurality of passages 67, reaches the valve opening pressure of the main valve 51, the main valve 51 opens, and the working fluid in the annular flow path 21 passes through the recess 66, the plurality of passages 67, the annular recess 55, the main valve 51, and the flow path 26 on the outer periphery of the main valve 51 and flows (is discharged) from the opening 24 of the outer tube 3 to the reservoir 4.

[0042] In this way, the damping force adjustment mechanism 30 generates a soft characteristic damping force according to the valve opening pressures of the introduction orifice 94 and the pilot valve 71 (valve body 103) before the main valve 51 opens (in the low piston speed range) during both the extension stroke and the contraction stroke of the piston rod 6, and generates a hard characteristic damping force according to the opening degree of the main valve 51 after the main valve 51 opens (in the medium piston speed range).

[0043] By controlling the energization of coil 126 to adjust the opening pressure of pilot valve 71, the damping force can be directly controlled regardless of the piston speed. Also, by controlling the energization of coil 126 to adjust the opening pressure of pilot valve 71, it is possible to open back pressure introduction valve 81 and adjust the pressure of the working fluid introduced into back pressure chamber 72, and the damping force characteristics can be adjusted over a wide range.

[0044] Also, when a fail occurs such as a disconnection of coil 126 or a failure of the in-vehicle controller, if the thrust of movable iron core 129 (operating rod 130) is lost, the valve body 103 is retracted by the spring force of return spring 112 to open pilot valve 71, and the spring receiving portion 104 of valve body 103 is brought into contact with fail-safe disk 113, thereby blocking the communication between valve chamber 100 and flow path 26 inside valve case 25.

[0045] In this way, the fail-safe valve 111 controls the flow of the working fluid flowing from the annular flow path 21 to the reservoir 4 via the introduction orifice 94, passage 93, small inner diameter portion 91, passage 101, valve chamber 100, notch 116, flow path 117, passage 118, flow path 26, and opening 24. By varying the opening pressure of the fail-safe valve 111, it is possible to obtain a damping force corresponding to the opening pressure. At the same time, since the internal pressure of the back pressure chamber 72, and thus the opening pressure of the main valve 51, can be adjusted, it is possible to obtain a certain damping force even when a fail occurs.

[0046] The working fluid flowing from the opening 24 to the reservoir 4 is enclosed in the space inside the partition portion 37 of the baffle plate 31 (partition member), so it is isolated from the liquid level of the working fluid in the reservoir 4. Further, the baffle plate 31 suppresses the movement of the working fluid flowing from the opening 24 to the reservoir 4 in the upward direction and the circumferential direction of the separator tube 20, so it is possible to prevent the jet flow of the working fluid flowing from the opening 24 to the reservoir 4 from generating vortices and bubbles near the liquid level of the working fluid in the reservoir 4.

[0047] In this way, the baffle plate 31 suppresses the generation of aeration caused by the stirring of the gas and the working fluid, so that a stable damping force can be obtained. Further, the baffle plate 31 alleviates the sudden expansion of the flow path area of the working fluid flowing from the damping force adjustment mechanism 30 to the reservoir 4, so that a sudden increase in the flow velocity of the working fluid flowing into the reservoir 4 is suppressed, and the generation of vortices can be suppressed. As a result, the generation of cavitation due to the generation of vortices is also suppressed, so that a stable damping force can be obtained.

[0048] Here, in a conventional shock absorber, by connecting the main body of the damping force adjustment mechanism to a separator tube (intermediate cylinder) without providing a connecting member, the axial length of the valve mechanism portion can be shortened and the damping force adjustment mechanism can be miniaturized. In this case, in order to avoid interference between the main body and the outer tube (outer cylinder), the aperture diameter of the opening formed in the outer tube becomes large, and accordingly, the baffle plate becomes large. When the cylinder is centered with respect to the outer tube during the assembly of the rod guide, the partition wall portion of the baffle plate is pressurized (compressed) between the outer tube and the separator tube attached to the cylinder, but due to the increase in the elastic reaction force (assembly load) of the partition wall portion of the enlarged baffle plate, centering becomes difficult and the assemblability deteriorates.

[0049] On the other hand, in the present embodiment, by providing the cutout portions 41 on the outside of the upper partition wall 38 located above the center of the connecting pipe 23 of the separator tube 20, which generates most of the elastic reaction force of the partition wall member 37, and on a pair of lower partition walls 46 extending downward from both ends of the upper partition wall 38, the volume of the upper partition wall 38 is set to be equal to the volume of the upper partition wall in the conventional baffle plate. According to the present embodiment, when the outer tube is centered with respect to the cylinder 2 to which the separator tube 20 (intermediate cylinder) is attached during the assembly of the rod guide 8, an increase in the elastic reaction force of the partition wall portion 37 of the baffle plate 31 is suppressed, so that the assembly load (elastic reaction force) can be made equivalent to that of the conventional shock absorber, and the assemblability of the shock absorber 1 can be ensured without impairing the performance of the baffle plate 31.

[0050] Note that this embodiment is not limited to the above-described aspects, and can be configured as follows, for example. In the above-described aspect, the cutout portion 41 is provided on the outer side (outer surface 40) of the upper partition wall 38 and the lower partition wall 46. However, as shown in FIG. 7, the cutout portion 41 may be provided on the inner side (inner surface 39) of the upper partition wall 38 and the lower partition wall 46, and the baffle plate 31 may be configured such that the volumes of the upper partition wall 38 and the lower partition wall 46 are set to be equal to the volumes of the upper partition wall and the lower partition wall 46 in the conventional baffle plate. The broken line 42 in FIG. 7 is the inner surface of the baffle plate in the conventional shock absorber. Alternatively, cutout portions 41 may be provided on both the outer and inner sides of the upper partition wall 38 and the lower partition wall 46, and the baffle plate 31 may be configured to adjust the volume of the upper partition wall 38. In this embodiment, the cutout portion 41 is provided on the upper partition wall 38 and the lower partition wall 46. However, the cutout portion 41 may be provided on either the upper partition wall 38 or the lower partition wall 46 to configure the baffle plate 31. Any of these aspects can achieve the above-described effects. Also, as shown in FIG. 8, a notch 48 (cutout portion) may be provided in the lower partition wall 46, and the baffle plate 31 may be configured to adjust the rigidity (elastic reaction force) of the entire partition wall portion 37. The number, shape, and position of the notch 48 can be set as appropriate.

Explanation of Reference Numerals

[0051] 1 Shock absorber, 2 Cylinder, 2A Upper cylinder chamber, 2B Lower cylinder chamber, 3 Outer tube (outer cylinder), 4 Reservoir, 5 Piston, 20 Separator tube (intermediate cylinder), 21 Annular flow path, 22 Communication path, 23 Connecting tube, 24 Opening, 30 Damping force adjustment mechanism, 31 Baffle plate (partition member), 38 Upper partition wall, 41 Cutout portion, 46 Lower partition wall

Claims

1. a cylinder in which a working fluid is enclosed; a piston slidably inserted into the cylinder and partitioning the inside of the cylinder into an upper cylinder chamber and a lower cylinder chamber; a piston rod having one end connected to the piston and the other end extending to the outside of the cylinder; an outer cylinder provided on the outer periphery of the cylinder; a reservoir formed between the cylinder and the outer cylinder; an intermediate cylinder provided on the outer periphery of the cylinder and having both ends fitted to the cylinder; an annular flow path formed between the cylinder and the intermediate cylinder; a communication path provided on the side wall of the cylinder and communicating the upper cylinder chamber and the annular flow path; a connecting pipe provided on the side wall of the intermediate cylinder; an opening provided on the side wall of the outer cylinder and opening at a position facing the connecting pipe; a damping force adjusting mechanism connected to the connecting pipe; a partition member provided in the reservoir and having a partition portion for controlling the flow direction of the working fluid flowing from the upper cylinder chamber, through the communication path, the annular flow path, the damping force adjusting mechanism, and into the reservoir through the opening; a shock absorber comprising: the partition portion includes an upper partition portion located above the center of the connecting pipe and extending in an arc shape in a front view, and a pair of lower partition portions extending downward from both ends of the upper partition portion; the upper partition portion has a groove formed on the inner side, an upper end portion protruding outward, an outer surface inclined from the upper end portion, and an R portion formed between the upper end portion and the outer surface; the lower partition portion has a notch for adjusting the rigidity of the partition portion. A shock absorber characterized by this.

2. The shock absorber according to claim 1, wherein the groove is provided inside the lower partition portion. A shock absorber characterized by this.

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