Buffer

Abstract

The present invention addresses the problem of providing a shock absorber that suppresses leakage of hydraulic fluid from between a disc valve and a sub-check valve provided at a passage opening of an orifice passage.　A sub-check valve (133) is urged toward an opening (126) of an orifice passage (130) by an urging disk (135) (urging member) having substantially the same diameter as the sub-check valve (133). As a result, when a piston speed in an extension stroke is low (0.1 m / s or less not including 0), hydraulic fluid in a first chamber (2A) is stopped from leaking from between a disc valve (121) and the sub-check valve (133) into a second chamber (2B), and the intended damping force can be obtained.

Description

Technical Field

[0001] The present invention relates to a shock absorber that controls the flow of working fluid with respect to the piston stroke to vary the damping force.

Background Art

[0002] Patent Document 1 discloses a damping force adjustable shock absorber 1 configured to close an opening 54 (passage opening) of an orifice passage formed in a check valve 13 (disk valve) with a sub-check valve disk 45 (sub-check valve).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the shock absorber described in Patent Document 1, when the sub-check valve disk 45 is in the closing stroke, the working fluid enters between the sub-check valve disk 45 and the seat disk 46, passes through the orifice passage, and leaks into the cylinder chamber, which may prevent the intended damping force from being obtained.

[0005] An object of the present invention is to provide a shock absorber that suppresses leakage of the working fluid from between a sub-check valve provided at the passage opening of the orifice passage and a disk valve.

Means for Solving the Problems

[0006] The shock absorber of the present invention includes a cylinder filled with working fluid, a reservoir filled with working fluid and gas, a piston slidably inserted into the cylinder and partitioning the inside of the cylinder into a first chamber and a second chamber, a base valve partitioning the second chamber and the reservoir, a first check valve provided on the piston and allowing the flow of the working fluid from the second chamber side to the first chamber side, a second check valve provided on the base valve and allowing the flow of the working fluid from the reservoir side to the second chamber side, a passage connecting the first chamber and the reservoir, and a damping force adjustment mechanism capable of adjusting the damping force from the outside from a soft characteristic with a low damping force to a hard characteristic with a high damping force by controlling the flow of the working fluid in the passage. An orifice passage is provided in parallel with the first check valve, and a sub-check valve is provided at the passage opening of the orifice passage. The sub-check valve is configured to open at a lower pressure than the check valve provided in parallel with the orifice passage and allow the flow of the working fluid in the same direction. The sub-check valve is provided with a biasing member having substantially the same diameter as the sub-check valve and biasing the sub-check valve toward the passage opening. The biasing member is formed with a protrusion that generates a biasing force toward the sub-check valve on the outer peripheral side of the biasing member and a hole provided radially inward of the protrusion. The Sub check valve is formed of a disk, A disk valve composed of a plurality of disks including the sub-check valve is provided. A part of the orifice passage extends radially inward from the outer peripheral edge of the disk The disks constituting the valve to form a notch, by and the passage opening is Among the plurality of disks, it is provided on the disk that abuts on the disk in which the notch is formed. The radially inner end of the hole is arranged to be located radially inward of the radially inner end of the passage opening, and the radially outer end of the hole is arranged to be located radially outward of the radially inner end of the passage opening. The protrusion is arranged to face the passage opening. [[ / END]]

[0007] According to an embodiment of the present invention, in a shock absorber in which an orifice passage is formed in a disk valve laminated on a piston, it is possible to suppress the leakage of the working fluid between the sub-check valve provided at the passage opening of the orifice passage and the disk valve.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Mode for Carrying Out the Invention

[0009] (First Embodiment) The first embodiment of the present invention will be described with reference to the attached drawings. The shock absorber 1 shown in FIG. 1 is a so-called control valve side-mounted type damping force adjustable hydraulic shock absorber in which the damping force adjustment mechanism 31 is mounted horizontally on the side wall of the outer tube 3. For convenience, the vertical direction in FIG. 1 is referred to as the "vertical direction". Also, the left direction (left side) in FIG. 2 is referred to as the "cylinder direction (cylinder side)", and the right direction (right side) is referred to as the "anti-cylinder direction (anti-cylinder side)".

[0010] The shock absorber 1 has a double-cylinder structure in which a cylinder 2 is provided inside the outer tube 3, and a reservoir 4 is formed between the cylinder 2 and the outer tube 3. Inside the cylinder 2, a piston 5 that divides the inside of the cylinder 2 into two chambers, a first chamber 2A and a second chamber 2B, is slidably inserted. The shock absorber 1 has a piston rod 6 whose lower end side (one end side) is connected to the piston 5 and whose upper end side (the other end side) extends outside the cylinder 2 through the first chamber 2A. The piston rod 6 is inserted through a rod guide 7 attached to the upper end of the cylinder 2. The first chamber 2A and the outside are sealed by an oil seal 9 joined to a washer 8.

[0011] The piston 5 is provided with an extending-side passage 11 and a contracting-side passage 12 that communicate the first chamber 2A and the second chamber 2B. The extending-side passage 11 is provided with a disk valve 121 that opens when the pressure on the first chamber 2A side reaches the set pressure and releases the pressure on the first chamber 2A side to the second chamber 2B side. On the other hand, the contracting-side passage 12 is provided with a disk valve 14 (first check valve) that allows the flow of the working fluid from the second chamber 2B to the first chamber 2A. The disk valve 121 and the disk valve 14 are clamped under pressure between the washers 38, 38 by tightening a nut 13 screwed onto the lower end of the piston rod 6.

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

[0013] A separator tube 20 is attached to the outer periphery of the cylinder 2. An annular oil passage 21 sealed by a pair of upper and lower seal members 19, 19 is formed between the cylinder 2 and the separator tube 20. A passage 22 that communicates the annular oil passage 21 and the first chamber 2A is provided in the upper side wall of the cylinder 2. A cylindrical connection port 23 that protrudes toward the non-cylinder side is provided in the lower side wall of the separator tube 20. A mounting hole 24 is provided in the side wall of the outer tube 3 coaxially with the connection port 23. A cylindrical case 25 that surrounds the mounting hole 24 is provided in the side wall of the outer tube 3.

[0014] As shown in FIG. 2, a damping force adjustment mechanism 31 is housed in the case 25. The damping force adjustment mechanism 31 includes a valve block 33 in which valve components are integrated, and a solenoid block 101 in which solenoid components are integrated. The valve block 33 has a back-pressure type main valve 41, a pilot valve 61 that controls the valve opening pressure of the main valve 41, and a fail-safe valve 91 provided downstream of the pilot valve 61. That is, the damping force adjustment mechanism 31 is a pilot type pressure control valve that controls the valve opening pressure of the pilot valve 61.

[0015] A joint member 28 is inserted into the mounting hole 24 of the outer tube 3. The joint member 28 has a cylindrical tube portion 29 whose cylinder-side end is inserted into the connection port 23, and a flange portion 30 (outer flange) provided at the peripheral edge of the opening on the side opposite to the cylinder of the tube portion 29 and disposed in the case 25. The tube portion 29 and the flange portion 30 are covered with a sealing material. The flange portion 30 has its cylinder-side end face abutted against the end face on the side opposite to the cylinder of the inner flange portion 26 of the case 25, and its end face on the side opposite to the cylinder abutted against the annular end face (reference numeral omitted) on the cylinder side of the main body 42. The flow path 35 on the outer periphery of the valve block 33 and the reservoir 4 are communicated with each other by a plurality of grooves 27 provided in the inner flange portion 26 of the case 25.

[0016] The valve block 33 includes an annular main body 42, an annular pilot body 62, and a pilot pin 63 that connects the main body 42 and the pilot body 62. An annular seat portion 43 protruding toward the side opposite to the cylinder is formed at the outer peripheral edge portion of the end face on the side opposite to the cylinder of the main body 42. The outer peripheral edge portion of the main disk 44 is detachably abutted against the seat portion 43.

[0017] The inner peripheral portion of the main disk 44 is clamped between the inner sheet portion 45 of the main body 42 and the large-diameter portion 64 of the pilot pin 63. An annular packing 46 is provided on the outer peripheral portion of the main disk 44 on the side opposite to the cylinder. An annular recess 47 is provided on the end face of the main body 42 on the side opposite to the cylinder. When the main disk 44 seats on the seat portion 43, an annular passage 48 is formed between the main body 42 and the main disk 44. The annular passage 48 communicates with the flow passage 35 through an orifice 52 formed in the main disk 44. A recess 49 is formed at the center of the end face of the main body 42 on the cylinder side. The recess 49 and the annular recess 47 (annular passage 48) on the side opposite to the cylinder are communicated with each other by a plurality of (only "two" are shown in FIG. 2) passages 50 formed in the main body 42.

[0018] The pilot pin 63 is formed in a bottomed cylindrical shape with an opening on the side opposite to the cylinder. An introduction orifice 65 is formed at the bottom of the pilot pin 63 on the cylinder side. The cylinder side of the pilot pin 63 is press-fitted into the shaft hole 51 of the main body 42. The side of the pilot pin 63 opposite to the cylinder is press-fitted into the shaft hole 66 of the pilot body 62. A plurality of grooves 67 extending in the axial direction (the "left-right direction" in FIG. 2) are formed on the outer peripheral surface of the pilot pin 63 on the side opposite to the cylinder.

[0019] The pilot body 62 is formed in a slightly bottomed cylindrical shape with an opening on the side opposite to the cylinder. A flexible disk 69 clamped by the inner peripheral portion 68 of the pilot body 62 and the large-diameter portion 64 of the pilot pin 63 is provided on the cylinder side of the pilot body 62. A cylindrical portion 70 coaxial with the pilot body 62 is formed on the outer peripheral portion of the pilot body 62 on the cylinder side. The packing 46 of the main valve 41 is slidably abutted against the inner peripheral surface (reference numeral omitted) of the cylindrical portion 70. Thereby, a pilot chamber 71 is partitioned on the side opposite to the cylinder (the back surface) of the main disk 44. The pressure in the pilot chamber 71 acts on the main disk 44 in the valve closing direction (the direction of pressing against the seat portion 43).

[0020] At the bottom of the pilot body 62, a plurality of axially extending passages 72 (only "two" are shown in FIG. 2) are provided at equal intervals in the circumferential direction. When the flexible disk 69 seats on the annular seat portion 73 provided on the cylinder-side end face of the pilot body 62, an annular chamber 74 is formed inside the seat portion 73. The cylinder side of the passage 72 opens into the chamber 74. The flexible disk 69 bends under the internal pressure of the pilot chamber 71, thereby imparting volume elasticity to the pilot chamber 71.

[0021] The flexible disk 69 is composed of a plurality of disks laminated together. A notch 75 communicating the groove 67 and the pilot chamber 71 is provided in the inner peripheral portion of the disk that abuts against the large-diameter portion 64 of the pilot pin 63. Thereby, the working fluid in the first chamber 2A is introduced into the damping force adjusting mechanism 31 via the passage 22, the annular oil passage 21, and the flow passage 36 (axial hole) of the joint member 28, and is introduced into the pilot chamber 71 via the introduction passage, that is, the introduction orifice 65, the axial hole 76 of the pilot pin 63, the groove 67, and the notch 75. On the other hand, the first chamber 2A is connected to the reservoir 4 by a passage. That is, the working fluid in the first chamber 2A is introduced into the damping force adjusting mechanism 31 via the passage 22, the annular oil passage 21, and the flow passage 36 (axial hole) of the joint member 28, and further flows to the reservoir 4 through the plurality of grooves 27 formed in the case 25 and the mounting holes 24 formed in the outer tube 3.

[0022] A recess 77 is formed on the anti-cylinder side of the pilot body 62. At the center of the bottom of the recess 77, an annular seat portion 79 (valve seat) against which the valve body 78 can be detachably seated is formed. The seat portion 79 is provided at the opening periphery of the axial hole 66 of the pilot body 62 through which the working fluid passes. The valve body 78 is formed in a substantially cylindrical shape, and the end portion on the cylinder side is formed in a tapered shape. An outer flange-shaped spring receiving portion 80 is provided on the anti-cylinder side of the valve body 78. The valve body 78 is biased in a direction away from the seat portion 79 (anti-cylinder direction) by the pilot spring 83.

[0023] On the anti-cylinder side of the pilot body 62, a cylindrical portion 81 is formed. In the cylindrical portion 81, a pilot spring 83, a spacer 93, a fail-safe disk 94, a retainer 95, a spacer 96, and a washer 97 are laminated in order from the cylinder side. A cap 98 attached to the outer periphery of the cylindrical portion 81 is placed over the laminated components. A notch 99 serving as a passage communicating the concave portion 77 (valve chamber) and the flow path 35 is formed in the cap 98.

[0024] The solenoid block 101 is formed by integrating a coil 103, a core 104, a core 105, a plunger 106, and a hollow operating rod 107 connected to the plunger 106 into a solenoid case 102. A spacer 108 and a cover 109 are inserted on the anti-cylinder side of the solenoid case 102. By plastically processing the edge portion on the anti-cylinder side of the solenoid case 102, an axial force is applied to the components inside the solenoid case 102.

[0025] The plunger 106 is supported so as to be movable in the axial direction by sleeves 113 and 114 provided on the core 104 and the core 105. The plunger 106 generates a thrust corresponding to the current value when an electric current is applied to the coil 103. The thrust generated by the plunger 106 acts to move the valve body 78 in the direction (cylinder direction) toward the seat portion 79 against the biasing force of the pilot spring 83.

[0026] The solenoid case 102 has its cylinder side inserted into the opening on the anti-cylinder side of the case 25. The space between the solenoid case 102 and the case 25 is sealed by a seal member 110. The cylinder side of the operating rod 107 protrudes into the concave portion 77 (valve chamber). A valve body 78 is attached to the end portion on the cylinder side of the operating rod 107. By tightening a nut 111 screwed onto the case 25 to compress an annular retaining ring 112, the solenoid case 102 and the case 25 are fixed, and the valve block 33 and the solenoid block 101 are coupled (integrated).

[0027] When the coil 103 is de-energized, the valve body 78 is biased in the anti-cylinder direction by the pilot spring 83, and the spring receiving portion 80 of the valve body 78 abuts (seats) against the fail-safe disk 94. On the other hand, when the coil 103 is energized, a thrust in the cylinder direction is generated in the plunger 106, and the operating rod 107 moves in the cylinder direction against the biasing force of the pilot spring 83, so that the valve body 78 is seated on the seat portion 79. The opening pressure of the valve body 78 is controlled by changing the current value of the energization to the coil 103 (hereinafter referred to as the "control current value"). In the soft mode with a small control current value, the pilot valve 61 is opened with a constant opening amount when the biasing force of the pilot spring 83 and the thrust of the plunger 106 are balanced.

[0028] Next, the main part of the first embodiment will be described with reference to FIG. 3. The disk valve 121 is composed of a plurality of disks clamped between a washer 38 and an annular inner seat portion 122 formed on the inner peripheral edge portion of the second chamber 2B side (the "lower side" in FIG. 3) of the piston 5. The disk valve 121 has a disk 125 that is detachably seated on an annular outer seat portion 123 formed on the outer peripheral edge portion of the second chamber side of the piston 5. A plurality of circular openings 126 (only "1" is shown in FIG. 3) are provided at equal intervals in the circumferential direction on the disk 125. An annular recess 124 is formed between the inner seat portion 122 and the outer seat portion 123.

[0029] The disk valve 121 has a disk 127 stacked on the anti-piston side (the "lower side" in FIG. 3) of the disk 125. The disk 127 has the same outer diameter as the disk 125. A plurality (only "1" is shown in FIG. 3) of notches 128 extending radially inward (the "left direction" in FIG. 3) are provided at equal intervals in the circumferential direction at the outer peripheral edge of the disk 127. The number of notches 128 is the same as the number of openings 126 provided in the disk 125, and the disks 125 and 127 are positioned around the axis so that the openings 126 and the notches 128 coincide (communicate). Further, the disk valve 121 has a plurality (six in the first embodiment) of disks 129 stacked on the anti-piston side of the disk 127. The disks 129 have the same outer diameter as the disks 125 and 127. In the first embodiment, the above configuration is adopted, but the outer diameters of the disks 127 and 125 may be different, and the notches 128 may be provided at unequal intervals. Also, although it is desirable to position the disks 125 and 127, depending on the shape and size of the notches and openings, positioning may not be necessary.

[0030] As a result, a plurality (only "1" is shown in FIG. 3) of orifice passages 130 composed of the notches 128 of the disk 127 and the openings 126 of the disk 125 are formed in the disk valve 121 (a plurality of disks stacked on the piston 5). The orifice passages 130 are provided on the second chamber 2B side of the piston 5 and are arranged in parallel with the disk valve 14 (the first check valve) provided in the first chamber 2A of the piston 5. The orifice passages 130 allow the working fluid in the second chamber 2B to flow to the first chamber 2A through the extension side passage 11 when the piston speed in the compression stroke is low (0.1 m / s or less, not including 0). The orifice area of the orifice passages 130 is the area of the rectangular cross-section of the notches 128. A spacer 131 and a retainer 132 are stacked on the anti-piston side of the disk 129.

[0031] On the piston side (the "upper side" in FIG. 3) of the disk 125, a disk-shaped sub-check valve 133 is provided in a stacked manner. The outer diameter of the sub-check valve 133 is set to be able to close the opening 126 of the disk 125, and thus the opening 126 (passage opening) of the orifice passage 130. Also, the outer diameter of the sub-check valve 133 is set such that the outer peripheral edge does not contact the piston 5, that is, the valve opening (lifting off from the disk 125) is not inhibited. Note that the sub-check valve 133 as a valve body includes those that allow flow from one direction and slightly allow flow from the other direction, rather than completely not allowing flow from the other direction.

[0032] Here, the outer sheet portion 123 protrudes from the piston 5 more than the inner sheet portion 122. That is, a certain step is formed between the inner sheet portion 122 and the outer sheet portion 123. Therefore, the disk valve 121 is pushed up by the outer sheet portion 123 and bends (elastically deforms), and a setting load acts on the disk valve 121.

[0033] On the piston side of the sub-check valve 133, a biasing disk 135 (biasing member) is provided in a stacked manner. The biasing disk 135 biases the sub-check valve 133 toward the disk valve 121 in the anti-piston direction and presses (adheres) the sub-check valve 133 against the disk 125 to close the opening 126 (passage opening) of the orifice passage 130.

[0034] As shown in FIG. 4, the biasing disk 135 has a shaft hole 136 (insertion hole) through which the piston rod 6 is inserted. An inner peripheral portion 137 is formed at the periphery of the shaft hole 136 and is clamped between the inner sheet portion 122 of the piston 5 and the disk valve 121 together with the inner peripheral portion (reference numeral omitted) of the sub-check valve 133. Also, the biasing disk 135 is formed with protrusions 138 that extend annularly along the outer peripheral edge.

[0035] The protrusion 138 is formed in an arc shape protruding toward the anti-piston side (the "lower side" in FIG. 3) in the axial plane of the biasing disk 135. The protrusion 138 is arranged to face the opening 126 (passage opening) of the orifice passage 130 (disk 125). Thereby, the outer peripheral portion of the sub-check valve 133 is pressed toward the opening 126 of the orifice passage 130. The biasing disk 135 has substantially the same diameter as the sub-check valve 133. Here, "substantially the same diameter" is intended to mean the outer diameter of the biasing disk 135 such that the opening of the sub-check valve 133 is not inhibited and the protrusion 138 can be arranged to face the opening 126 of the orifice passage 130, including the same outer diameter as the sub-check valve 133.

[0036] The biasing disk 135 has a plurality (in the first embodiment, "four") of holes 139 formed on the inner peripheral side of the protrusion 138. The holes 139 extend along the protrusion 138 with a constant width and are arranged at equal intervals on the outer periphery of the axial hole 136. Here, the biasing force of the biasing disk 135 is set such that the sub-check valve 133 opens at a lower pressure with respect to the disk valve 14 (first check valve) provided on the first chamber 2A side of the piston 5. That is, the sub-check valve 133 generates a damping force of the orifice characteristic by the orifice passage 130 by opening at a lower pressure than the disk valve 14 during the compression stroke.

[0037] Next, the flow of the working fluid in the shock absorber 1 will be described. During the extension stroke, the disk valve 14 (first check valve) of the piston 5 closes due to the pressure increase in the first chamber 2A, and before the disk valve 121 opens, the working fluid in the first chamber 2A is pressurized. The pressurized working fluid is introduced into the damping force adjustment mechanism 31 through the passage 22, the annular oil passage 21, and the flow passage 36 (axial hole) of the joint member 28. At this time, the working fluid corresponding to the movement of the piston 5 flows from the reservoir 4 into the second chamber 2B by opening the check valve 17 of the base valve 10. When the pressure in the first chamber 2A reaches the opening pressure of the disk valve 121 of the piston 5 and the disk valve 121 opens, the pressure in the first chamber 2A is relieved to the second chamber 2B, and an excessive pressure increase in the first chamber 2A is avoided.

[0038] During the compression stroke, due to the pressure increase in the second chamber 2B, the check valve 17 (second check valve) of the disk valve 121 and the base valve 10 of the piston 5 closes, and before the disk valve 18 of the base valve 10 opens, the hydraulic fluid in the second chamber 2B is pressurized. When the piston speed during the compression stroke is low (0.1 m / s or less excluding 0), the hydraulic fluid in the second chamber 2B opens the sub-check valve 133 against the biasing force of the biasing disk 135 (biasing member), and passes through the orifice passage 130 formed in the disk valve 121, the annular recess 124, the extension side passage 11, and the piston orifice 300 formed by coining, and flows into the first chamber 2A with the disk valve 14 closed. As a result, the shock absorber 1 generates a damping force with orifice characteristics due to the orifice passage 130.

[0039] When the disk valve 14 (first check valve) of the piston 5 opens and the hydraulic fluid in the lower chamber 2B of the piston flows into the first chamber 2A, the hydraulic fluid corresponding to the volume of the piston rod 6 that has entered the cylinder 2 is introduced from the first chamber 2A through the passage 22, the annular oil passage 21, and the flow passage 36 (axial hole) of the joint member 28 to the damping force adjustment mechanism 31. When the pressure in the second 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 second chamber 2B is relieved to the reservoir 4, and an excessive pressure increase in the second chamber 2B is avoided.

[0040] The hydraulic fluid introduced into the damping force adjustment mechanism 31 is introduced into the pilot chamber 71 through the introduction passage, that is, the introduction orifice 65, the axial hole 76 of the pilot pin 63, the groove 67, and the notch 75. On the other hand, the hydraulic fluid introduced into the damping force adjustment mechanism 31 flows to the reservoir 4 through the introduction orifice 65, the axial hole 76 of the pilot pin 63, the recess 77 (valve chamber) of the pilot body 62, the notch 99 formed in the cap 98, the flow passage 35 on the outer periphery of the valve block 33, the plurality of grooves 27 formed in the case 25, and the mounting hole 24 formed in the outer tube 3 before the main valve 41 opens (when the piston speed is in the low speed range).

[0041] When the piston speed increases and the pressure of the working fluid introduced into the damping force adjustment mechanism 31 reaches the valve opening pressure of the main valve 41, the working fluid opens the main valve 41 and flows to the reservoir 4 through the flow path 35 on the outer periphery of the valve block 33, the plurality of grooves 27 formed in the case 25, and the mounting holes 24 formed in the outer tube 3.

[0042] In this way, the damping force adjustment mechanism 31 generates a damping force when the working fluid passes through the introduction orifice 65 and the pilot valve 61 before the main valve 41 opens (when the piston speed is in the low speed range) during both the extension stroke and the contraction stroke of the piston rod 6. Also, after the main valve 41 opens (when the piston speed is in the medium speed range), a damping force with valve characteristics corresponding to the opening degree of the main valve 41 is generated. And by controlling the energization of the coil 103 and adjusting the valve opening pressure of the pilot valve 61, the damping force generated by the damping force adjustment mechanism 31 can be directly controlled.

[0043] Also, when the thrust of the plunger 106 is lost in the event of a failure such as a disconnection of the coil 103 or a failure of the in-vehicle controller, the valve body 78 is moved toward the anti-cylinder side by the biasing force of the pilot spring 83 (which also serves as a fail-safe spring), opening the pilot valve 61 and bringing the spring receiving portion 80 of the valve body 78 into contact with the fail-safe disk 94 to block the communication between the inner flow path (reference numeral omitted) of the valve block 33 and the outer flow path 35.

[0044] At this time, by adjusting the valve opening pressure of the fail-safe valve 91 and controlling the flow of the working fluid flowing from the first chamber 2A through the passage, that is, the passage 22, the annular oil passage 21, the flow path 36 (axial hole) of the joint member 28, the damping force adjustment mechanism 31, the plurality of grooves 27 formed in the case 25, and the mounting holes 24 formed in the outer tube 3 to the reservoir 4, a certain damping force can be generated in the event of a failure. At the same time, it is possible to adjust the internal pressure of the pilot chamber 71 and thus the valve opening pressure of the main valve 41, and a certain damping force can be obtained even in the event of a failure.

[0045] Here, in a conventional shock absorber (hereinafter referred to as the "conventional shock absorber") in which a sub-check valve 133 is provided at an opening 126 (passage opening) of an orifice passage 130 formed in a disk valve 121 (a plurality of disks laminated on a piston 5), the outer sheet portion 123 is higher than the inner sheet portion 122 (the protruding amount from the piston 5 is large), and the sub-check valve 133 is not seated on the outer sheet portion 123 (the outer diameter is smaller than that of the outer sheet portion 123). Therefore, in the conventional shock absorber, when the piston speed in the extension stroke is low (0.1 m / s or less excluding 0), the working fluid in the first chamber 2A may leak from between the disk valve 121 (disk 125) and the sub-check valve 133 to the second chamber 2B, and there is a possibility that the intended damping force (predetermined damping force) cannot be obtained.

[0046] Therefore, in the first embodiment, the shock absorber 1 is configured such that a biasing disk 135 (biasing member) having substantially the same diameter as the sub-check valve 133 biases the sub-check valve 133 toward the opening 126 of the orifice passage 130. Thereby, when the piston speed in the extension stroke is low (0.1 m / s or less excluding 0), leakage of the working fluid in the first chamber 2A from between the disk valve 121 and the sub-check valve 133 to the second chamber 2B is suppressed, and the intended damping force can be obtained. Further, in the first embodiment, the annular protrusion 138 formed on the biasing disk 135 biases (presses) the outer peripheral side of the sub-check valve 133 in the anti-piston direction to bring it into close contact with the disk valve 121, so that a gap between the disk valve 121 and the sub-check valve 133 can be reliably suppressed from occurring. Further, in the first embodiment, a plurality of holes 139 extending along the inner periphery of the protrusion 138 are provided between the protrusion 138 and the shaft hole 136 (insertion hole) of the biasing disk 135, so that the biasing disk 135 can be made to have low rigidity. Thereby, when the piston speed in the contraction stroke is low, the sub-check valve 133 can be opened before the disk valve 14 (first check valve) provided on the first chamber 2A side of the piston 5 is opened, and the damping force of the orifice characteristic by the orifice passage 130 can be obtained.

[0047] Furthermore, with reference to FIG. 5, the operation and effect of the biasing disk 135 (biasing member) used in the first embodiment will be described. Here, FIG. 5(A) shows a Lissajous waveform in a conventional shock absorber not provided with the biasing disk 135, and FIG. 5(B) shows a Lissajous waveform in the shock absorber 1 according to the first embodiment provided with the biasing disk 135.

[0048] First, the damping force F0 (see FIG. 5(A)) generated by a conventional shock absorber and the damping force F1 (see FIG. 5(B)) generated by the shock absorber 1 according to the first embodiment when the piston speed in the extension stroke is extremely low (for example, "0.05 m / s") are compared. From FIG. 5, it is clear that the damping force F1 generated by the shock absorber 1 according to the first embodiment is greater than the damping force F0 generated by the conventional shock absorber (F1 > F0). Here, if the damping force F0 generated by the conventional shock absorber is set to "1", the damping force F1 generated by the shock absorber 1 according to the first embodiment is approximately "2".

[0049] From this, it is presumed that in a conventional shock absorber not provided with the biasing disk 135, when the piston speed in the extension stroke is low, the working fluid in the first chamber 2A leaks from between the disk valve 121 (disk 125) and the sub-check valve 133 to the second chamber 2B, resulting in a loss of damping force (the intended damping force is not obtained).

[0050] On the other hand, in the shock absorber 1 according to the first embodiment, by biasing the sub-check valve 133 toward the opening 126 (passage opening) of the orifice passage 130 with the biasing disk 135, leakage of the working fluid from between the disk valve 121 and the sub-check valve 133 is suppressed, and it can be seen that the intended damping force is obtained even when the piston speed in the extension stroke is extremely low. Thus, in the first embodiment, the ride comfort of the vehicle when the piston speed is extremely low can be improved.

[0051] Next, when the piston speed is low (for example, "0.5 m / s"), compare the rising waveform S0 of the extension-side damping force generated by the conventional shock absorber at the time of piston stroke reversal (see Fig. 5(A)) with the rising waveform S1 of the extension-side damping force generated by the shock absorber 1 according to the first embodiment at the time of piston stroke reversal (see Fig. 5(B)).

[0052] From Fig. 5, it can be seen that the rising waveform S0 of the extension-side damping force generated by the conventional shock absorber at the time of piston stroke reversal is missing. That is, in the conventional shock absorber without the biasing disk 135, when the piston speed is low and the piston stroke is reversed, the working fluid in the first chamber 2A leaks from between the disk valve 121 (disk 125) and the sub-check valve 133 to the second chamber 2B, and it is presumed that the rise of the extension-side damping force is delayed.

[0053] On the other hand, in the shock absorber 1 according to the first embodiment, by biasing the sub-check valve 133 toward the opening 126 (passage opening) of the orifice passage 130 with the biasing disk 135, leakage of the working fluid from between the disk valve 121 and the sub-check valve 133 is suppressed. When the piston stroke is reversed at a low piston speed, it can be seen that there is no notch in the waveform S1 and the rise of the damping force is not delayed, and the intended damping force is obtained. Thus, in the first embodiment, the riding comfort of the vehicle when the piston speed is low can be improved.

[0054] Next, comparing the reserve waveform during the compression stroke in the conventional shock absorber with the reserve waveform during the compression stroke in the shock absorber 1 according to the first embodiment, the reserve waveform during the compression stroke in the conventional shock absorber and the reserve waveform during the compression stroke in the shock absorber 1 according to the first embodiment are substantially the same. That is, it can be seen that the damping force during the compression stroke in the shock absorber 1 according to the first embodiment does not change due to the provision of the biasing disk 135 on the sub-check valve 133 compared to the damping force during the compression stroke in the conventional shock absorber. Thus, in the first embodiment, during the compression stroke, damping force characteristics equivalent to those of the conventional shock absorber can be obtained.

[0055] Note that the embodiments are not limited to the forms described above, and for example, they can be configured as follows. In the first embodiment, a valve structure including an orifice passage 130, a sub-check valve 133, and a biasing disk 135 (biasing member) provided on the second chamber 2B side of the piston 5 (hereinafter referred to as the "valve structure of the first embodiment") can be provided on the first chamber 2A side of the piston 5 to constitute the shock absorber 1. That is, in the first embodiment, the sub-check valve 133 is arranged on the second chamber 2B side of the piston 5, but the disk valve 121 is provided on the first chamber 2A side of the piston 5, and the biasing disk 135 (biasing member) arranged on the side farthest from the piston biases the sub-check valve 133 toward the opening 126 (passage opening) of the orifice passage 130 formed in the disk valve 121 toward the piston side, so that the shock absorber 1 can be configured. At that time, the piston orifice 300 formed by coining is not provided. In this case, when the piston speed in the extension stroke is low, the working fluid in the second chamber 2B is prevented from leaking from between the disk valve 121 and the sub-check valve 133 into the first chamber 2A, and the intended damping force can be obtained. Note that in the first embodiment, a configuration in which the working fluid in the second chamber 2B is prevented from leaking from between the disk valve 121 and the sub-check valve 133 into the first chamber 2A when the piston speed in the extension stroke is low is shown, but the present invention may be applied to the compression stroke.

[0056] In addition, the valve structure of the first embodiment can be provided in the base valve 10 to constitute the shock absorber 1. That is, in the first embodiment, an orifice passage 130 is provided in parallel with the disk valve 14 (first check valve) provided on the piston 5, and a sub-check valve 135 is provided at the opening 126 (passage opening) of the orifice passage 130. However, the disk valve 121 is provided on the reservoir 4 side of the base valve 10, and an orifice passage 130 is provided in parallel with the check valve 17 (second check valve) provided in the base valve 10. The shock absorber 1 can be configured such that the sub-check valve 133 is biased toward the anti-base valve side toward the opening 126 (passage opening) of the orifice passage 130 formed in the disk valve 121 by the biasing disk 135 (biasing member). In this case, when the piston speed in the compression stroke is low, the working fluid in the second chamber 2B is prevented from leaking from between the disk valve 121 and the sub-check valve 133 to the reservoir 4, and the intended damping force can be obtained.

[0057] In addition, in the first embodiment, the mode in which the valve structure is applied to the shock absorber 1 provided with a damping force adjustment mechanism 31 (pilot type pressure control valve) that adjusts the opening pressure of the pilot valve 61 by energizing the coil 103 has been described. However, the valve structure of the first embodiment can be applied to a shock absorber (not shown) provided with a damping force adjustment mechanism (pilot type flow control valve) that adjusts the opening area of the pilot valve 61 by energizing the coil 103. In this case, the same operational effects as those of the first embodiment described above can be obtained.

[0058] (Second Embodiment) Next, the second embodiment will be described with reference to FIGS. 3 and 6. Here, the differences from the first embodiment will be described. For the common parts with the first embodiment, the same names and reference numerals are used.

[0059] In the first embodiment, a damping force adjustment mechanism 31 is applied to a double-tube shock absorber 1 horizontally attached to the side wall of an outer tube 3, that is, a so-called control valve horizontally attached type damping force adjustable hydraulic shock absorber, and the valve structure shown in FIG. 3 is applied. On the other hand, in the second embodiment, the valve structure (see FIG. 3) of the first embodiment is applied to a single-tube shock absorber 100.

[0060] The shock absorber 100 includes a cylinder 2 filled with a working fluid, a piston 5 and a free piston 117 slidably inserted into the cylinder 2. The piston 5 divides the inside of the cylinder 2 into a first chamber 2A and a second chamber 2B. On the other hand, the free piston 117 defines a gas chamber 118 at the bottom of the cylinder 2. A disk valve 14 (first damping valve) that allows the flow of the working fluid from the second chamber 2B to the first chamber 2A is provided on the first chamber 2A side of the piston 5.

[0061] Also, a disk valve 121 composed of a plurality of disks is laminated on the second chamber 2B side of the piston 5. As shown in FIG. 3, an orifice passage 130 provided in parallel with the disk valve 14 (first damping valve) is formed in the disk valve 121. A sub check valve 133 that opens at a lower pressure than the disk valve 14 and allows the flow of the working fluid in the same direction (from the second chamber 2B to the first chamber 2A) is provided at an opening 126 (passage opening) of the orifice passage 130. An urging disk 135 (urging member) that urges the sub check valve 133 toward the opening 126 (passage opening) of the orifice passage 130 is provided on the sub check valve 133.

[0062] In the second embodiment, when the piston speed in the extension stroke is low, the leakage of the working fluid in the first chamber 2A to the second chamber 2B between the disk valve 121 and the sub check valve 133 is suppressed, and it is possible to obtain an intended damping force, and the same operational effects as those of the first embodiment described above can be obtained. In the present embodiment, an urging disk 135 is provided separately from the sub-check valve 133. However, for example, by forming an R portion that protrudes toward the annular recess 124 side at least near the opening 126 of the sub-check valve, the sub-check valve 133 itself may be configured to generate an urging force toward the disk valve 121 side without providing a separate urging disk. Also, an urging seat portion for urging the sub-check valve 133 may be provided between the inner seat portion 122 and the outer seat portion 123 of the piston 5, and the sub-check valve 133 may be urged toward the disk valve 121 side by the urging seat portion. In that case, it is preferable that the urging seat portion is positioned and has a protruding height that does not obstruct the opening of the sub-check valve 133. Also, the urging disk 135 does not necessarily have to be disk-shaped as in the second embodiment, and may be a star spring or a coil spring.

[0063] Note that the present invention is not limited to the above-described embodiments, and includes various modifications. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Also, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Also, for a part of the configuration of each embodiment, addition, deletion, or replacement with other configurations is possible.

[0064] This application claims priority based on Japanese Patent Application No. 2021-066573 filed on April 9, 2021. The entire disclosure content including the specification, claims, drawings, and abstract of Japanese Patent Application No. 2021-066573 filed on April 9, 2021 is incorporated herein by reference in its entirety.

Explanation of Reference Numerals

[0065] 1 Buffer, 2 Cylinder, 2A First Chamber, 2B Second Chamber, 4 Reservoir, 5 Piston, 6 Piston Rod, 10 Base Valve, 14 Disc Valve (First Check Valve), 17 Check Valve (Second Check Valve), 31 Damping Force Adjustment Mechanism, 126 Opening (Passage Opening), 130 Orifice Passage, 133 Sub Check Valve (Valve Body), 135 Biasing Disc (Biasing Member)

Claims

1. a cylinder filled with hydraulic fluid; a reservoir filled with hydraulic fluid and gas; a piston slidably inserted into the cylinder and partitioning the inside of the cylinder into a first chamber and a second chamber; a base valve partitioning the second chamber and the reservoir; a first check valve provided on the piston and allowing the flow of hydraulic fluid from the second chamber side to the first chamber side; a second check valve provided on the base valve and allowing the flow of hydraulic fluid from the reservoir side to the second chamber side; a passage connecting the first chamber and the reservoir; a damping force adjustment mechanism capable of adjusting the damping force from the outside from a soft characteristic with a low damping force to a hard characteristic with a high damping force by controlling the flow of the hydraulic fluid in the passage; and an orifice passage is provided in parallel with the first check valve, and a sub-check valve is provided at the passage opening of the orifice passage; the sub-check valve is configured to open at a lower pressure than the check valve provided in parallel with the orifice passage and allow the flow of hydraulic fluid in the same direction; the sub-check valve is provided with a biasing member having substantially the same diameter as the sub-check valve and biasing the sub-check valve toward the passage opening; the biasing member is formed with a protrusion that generates a biasing force toward the sub-check valve on the outer peripheral side of the biasing member and a hole provided radially inward of the protrusion; the sub-check valve is formed of a disk; a disk valve composed of a plurality of disks including the sub-check valve is provided; a part of the orifice passage is formed by a notch extending radially inward from the outer peripheral edge of the disk constituting the disk valve; the passage opening is provided in the disk that abuts against the disk in which the notch is formed among the plurality of disks; the radially inner end of the hole is arranged to be located radially inward of the radially inner end of the passage opening; the radially outer end of the hole is arranged to be located radially outward of the radially inner end of the passage opening; the protrusion is arranged to face the passage opening, and a shock absorber characterized by this.

2. a cylinder filled with hydraulic fluid; a reservoir filled with hydraulic fluid and gas; a piston slidably inserted into the cylinder and partitioning the inside of the cylinder into a first chamber and a second chamber; a base valve partitioning the second chamber and the reservoir; a first check valve provided on the piston and allowing the flow of hydraulic fluid from the second chamber side to the first chamber side; A second check valve provided in the base valve and allowing the flow of the working fluid from the reservoir side to the second chamber side; A passage connecting the first chamber and the reservoir; A damping force adjusting mechanism capable of adjusting the damping force from the outside, by controlling the flow of the working fluid in the passage, from a soft characteristic with a low damping force to a hard characteristic with a high damping force; An orifice passage is provided in parallel with the first check valve, and a sub-check valve is provided at the passage opening of the orifice passage; The sub-check valve is configured to open at a lower pressure than the check valve provided with the orifice passage in parallel, and allow the flow of the working fluid in the same direction; The first check valve is disposed in the first chamber, and the sub-check valve is disposed in the second chamber; The sub-check valve is provided with a biasing member that biases the sub-check valve toward the passage opening; On the outer peripheral side of the biasing member, a protrusion that generates a biasing force toward the sub-check valve and a hole provided radially inward of the protrusion are formed; The sub-check valve is formed of a disk; A disk valve composed of a plurality of disks including the sub-check valve is provided; A part of the orifice passage is formed by a notch extending radially inward from the outer peripheral edge of the disk constituting the disk valve; The passage opening is provided in the disk that abuts against the disk in which the notch is formed among the plurality of disks; The radially inner end of the hole is arranged to be located radially inward of the radially inner end of the passage opening; The radially outer end of the hole is arranged to be located radially outward of the radially inner end of the passage opening; The buffer, characterized in that the protrusion is arranged to face the passage opening.

3. In the buffer according to claim 2, The orifice passage is constituted by a plurality of disks laminated on the piston; The buffer, characterized in that the biasing member generates a biasing force toward the anti-piston side.

4. In the buffer according to any one of claims 1 to 3, The buffer, characterized in that the biasing member is an annular disk, and a hole is formed on the inner peripheral side of the protrusion.

5. In the buffer according to claim 4, The buffer, characterized in that the protrusion extends annularly along the outer periphery of the biasing member.

6. In the buffer according to claim 4 or 5, The biasing member has a plurality of the holes, and an insertion hole for clamping and fixing to the piston is provided on the inner peripheral side of the holes. A shock absorber characterized by this.

7. In the shock absorber according to any one of Claims 1 to 6, The damping force adjusting mechanism is a pilot type pressure control valve that controls the opening pressure of a pilot valve. A shock absorber characterized by this.

8. In the shock absorber according to any one of Claims 1 to 6, The damping force adjusting mechanism is a pilot type flow control valve that controls the opening area of a pilot valve. A shock absorber characterized by this.

9. In the shock absorber according to any one of Claims 1 to 8, The piston speeds when the first and second check valves open are 0.1 m / s or less, not including 0. A shock absorber characterized by this.

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