JP7645167B2 - Adjustable damping shock absorber and solenoid - Google Patents

Description

The present invention relates to a damping force adjustable shock absorber that adjusts the damping force by controlling the flow of working fluid generated by the stroke of a piston rod, and a solenoid that adjusts the opening pressure of a damping valve in a damping force adjustable shock absorber.

Patent Document 1 describes a solenoid 33 in which a shaft portion 43 to which a movable iron core 38 is integrally fixed is supported by a pair of bushes 44, 45 so as to be movable in the axial direction, and a damping force adjustment shock absorber of a control valve side-mounted type equipped with the solenoid 33. The solenoid 33 has a bush 45 supporting the other end of the shaft portion 43, which is fitted into a bush fitting hole 46C formed on the inner periphery of a back pressure chamber forming member 46. The back pressure chamber forming member 46 is press-fitted into a small diameter portion 48C of a hat-shaped cap member 48.

JP 2017-211062 A

In the manufacturing process of the solenoid described in Patent Document 1, the back pressure chamber forming member 46 is press-fitted into the small diameter portion 48C of the cap member 48. If the back pressure chamber forming member 46 is tilted with respect to the axis of the cap member 48, the press-fit depth of the back pressure chamber forming member 46 into the cap member 48 becomes shallow.

In this case, the axial movement of the shaft portion 43 during the fail-safe state is restricted by the movable iron core 38 hitting the back pressure chamber forming member 46, so that the movement of the shaft portion 43 during the fail-safe state is stopped just before the flange portion 32A of the valve body 32 seats on the disk valve 29 (fail-safe disk). As a result, the working fluid flows through the gap between the valve body 32 and the disk valve 29, and the damping force during the fail-safe state is reduced.

The objective of the present invention is to provide a damping force adjustable shock absorber that prevents a decrease in damping force during fail-safe operation and a solenoid used in the damping force adjustable shock absorber.

The present invention provides a damping force control shock absorber comprising: a cylinder in which a working fluid is sealed; a piston fitted in the cylinder and dividing the interior of the cylinder into two chambers; a piston rod having one end connected to the piston and the other end protruding to the outside from an opening of the cylinder; a flow path in which a flow of the working fluid occurs as the piston rod expands and contracts; and a damping force adjustment mechanism provided in the flow path, in which a valve-opening pressure is adjusted by a thrust generated by a solenoid. The solenoid comprises a coil which generates a magnetic force when energized, a cylindrical cap member with a bottom disposed on the inner periphery of the coil, a movable iron core disposed on the inner periphery of the cap member and movable in the axial direction, a fixed iron core disposed axially opposite the movable iron core and attracting the movable iron core, and a damping force adjustment mechanism disposed in the cap member. the cap member has a large inner diameter portion into which the end of the fixed core facing the movable core is fitted, and a small inner diameter portion into which the bush support member is press-fitted, the bush support member having a large outer diameter portion formed on the valve body side, a small outer diameter portion formed on the bottom surface side of the cap member, and a tapered portion connecting the large outer diameter portion and the small outer diameter portion, and the small outer diameter portion has a chamfered portion formed on the bottom side of the cap member .
The solenoid of the present invention comprises a coil that generates a magnetic force when current is passed through it, a cylindrical cap member with a bottom arranged on the inner periphery of the coil, a movable iron core arranged on the inner periphery of the cap member and movable in the axial direction, a fixed iron core arranged axially opposite the movable iron core and attracting the movable iron core, a cylindrical bush support member with a bottom fitted to the bottom of the cap member, a pair of bushes arranged on the inner periphery of the bush support member and the fixed iron core, and an operating rod supported by the pair of bushes so as to be movable in the axial direction, wherein the cap member has a large inner diameter portion into which an end of the fixed iron core facing the movable iron core is fitted, and a small inner diameter portion into which the bush support member is press-fitted, and the bush support member has a large outer diameter portion formed on the fixed iron core side, a small outer diameter portion formed on the bottom surface side of the cap member, and a tapered portion connecting the large outer diameter portion and the small outer diameter portion, and the small outer diameter portion has a chamfered portion formed on the bottom side of the cap member .

The damping force adjustable shock absorber and solenoid of the present invention can prevent a decrease in damping force during fail-safe mode.

1 is a cross-sectional view of a damping force control shock absorber according to an embodiment of the present invention. FIG. 2 is an enlarged view of the damping force adjustment mechanism in FIG. FIG. 3 is an enlarged view of the fail-safe valve in FIG. 2 . FIG. 3 is a cross-sectional view of the cap member in FIG. 2 . 3 is a cross-sectional view of the bush support member shown in FIG. 2 .

An embodiment of the present invention will now be described with reference to the accompanying drawings.
Fig. 1 is a cross-sectional view of a so-called control valve side-mounted type hydraulic shock absorber 1 with a damping force adjustment mechanism 31 mounted sideways on the side of an outer tube 3 (hereinafter referred to as "damping force adjustable shock absorber 1"). For convenience, the up-down direction in Fig. 1 will be referred to as the "up-down direction".

The damping force adjustable shock absorber 1 has a double-cylinder structure in which a cylinder 2 is provided inside an outer tube 3, and a reservoir 4 is formed between the cylinder 2 and the outer tube 3. A piston 5 is slidably fitted inside the cylinder 2, dividing the inside of the cylinder 2 into two chambers, a cylinder upper chamber 2A and a cylinder lower chamber 2B. The damping force adjustable shock absorber 1 is equipped with a piston rod 6 whose lower end (one end) is connected to the piston 5 and whose upper end (the other end) passes through the cylinder upper chamber 2A and protrudes to the outside from an opening of the outer tube 3. The piston rod 6 is inserted into a rod guide 7 fitted to the upper end of the cylinder 2. An oil seal 9 attached to a washer 8 seals between the cylinder upper chamber 2A and the outside. A spring seat 85 is provided on the outer periphery of the outer tube 3.

The piston 5 is provided with an extension passage 11 and a compression passage 12 that connect the cylinder upper chamber 2A and the cylinder lower chamber 2B. The extension passage 11 is provided with a disk valve 13 (relief valve) that opens when the pressure on the cylinder upper chamber 2A side reaches a set pressure to release the pressure on the cylinder upper chamber 2A side to the cylinder lower chamber 2B side. The compression passage 12 is provided with a disk valve 14 (check valve) that allows the flow of working fluid from the cylinder lower chamber 2B to the cylinder upper chamber 2A.

At the lower end of the cylinder 2, a base valve 10 is provided to separate the cylinder lower chamber 2B from the reservoir 4. The base valve 10 is provided with an extension side passage 15 and a compression side passage 16 that communicate the cylinder lower chamber 2B with the reservoir 4. The extension side passage 15 is provided with a disk valve 17 (check valve) that allows the flow of working fluid from the reservoir 4 to the cylinder lower chamber 2B. The compression side passage 16 is provided with a disk valve 18 (relief valve) that opens when the pressure on the cylinder lower chamber 2B side reaches a set pressure to release the pressure on the cylinder lower chamber 2B side to the reservoir 4 side. Note that oil is sealed in the cylinder 2 as the working fluid, and oil and gas are sealed in the reservoir 4.

A separator tube 20 is attached to the outer periphery of the cylinder 2 via a pair of upper and lower seal members 19, 19. An annular oil passage 21 is formed between the cylinder 2 and the separator tube 20. A passage 22 is provided in the upper side wall of the cylinder 2, connecting the annular oil passage 21 to the cylinder upper chamber 2A. A cylindrical connection port 23 that protrudes to the right in FIG. 2 (outward in the cylinder radial direction) is provided in the lower side wall of the separator tube 20. A mounting hole 24 that is coaxial with the connection port 23 is provided in the side wall of the outer tube 3. A cylindrical case 25 that surrounds the mounting hole 24 is provided in the side wall of the outer tube 3.

As shown in FIG. 2, the case 25 houses the damping force adjustment mechanism 31. The damping force adjustment mechanism 31 includes a valve mechanism unit 33 with integrated valve components, and a solenoid 101. The valve mechanism unit 33 includes a back pressure type main valve 41, a pilot valve 61 that controls the opening pressure of the main valve 41, and a fail-safe valve 91 that is provided downstream of the pilot valve 61.

The 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, the end of which on the left side in FIG. 2 (inner side in the cylinder diameter direction) is inserted into the connection port 23, and a flange portion 30 that is provided on the periphery of the opening on the right side in FIG. 2 of the tube portion 29 and is housed in the case 25. The tube portion 29 and the flange portion 30 are covered with a sealing material. The left end face of the flange portion 30 in FIG. 2 abuts against the right end face in FIG. 2 of the inner flange portion 26 of the case 25, and the right end face in FIG. 2 abuts against the left annular end face (reference numeral omitted) of the main body 42 in FIG. 2. The flow path 35 on the outer periphery of the valve mechanism portion 33 and the reservoir 4 are connected by a plurality of passages 27 (grooves) provided in the inner flange portion 26 of the case 25.

The valve mechanism 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 is formed on the outer peripheral edge of the end face of the main body 42 on the right side in FIG. 2. The outer peripheral edge of the main disk 44 abuts against the seat portion 43 so that it can be seated and removed from the seat. The inner peripheral portion of the main disk 44 is clamped between the inner peripheral portion of the main body 42 and the large diameter portion 64 of the pilot pin 63.

A ring-shaped packing 46 is provided on the outer periphery of the right end face of the main disk 44 in FIG. 2. A ring-shaped recess 47 is provided on the right end face of the main body 42 in FIG. 2. When the main disk 44 is seated on the seat portion 43, a ring-shaped passage 48 is formed between the main body 42 and the main disk 44. The ring-shaped passage 48 is connected to the flow passage 35 on the outer periphery of the main body 42 through an orifice (reference number omitted) formed in the main disk 44. A recess 49 is formed in the center of the left end face of the main body 42 in FIG. 2. The recess 49 and the ring-shaped recess 47 (ring-shaped passage 48) on the right end face in FIG. 2 are connected by multiple passages 50 (only "two" are shown in FIG. 2) formed in the main body 42.

The pilot pin 63 is formed in a cylindrical shape with a bottom that opens to the end face on the right side in FIG. 2. An introduction orifice 65 is formed in the bottom of the left side of the pilot pin 63 in FIG. 2. The left end of the pilot pin 63 in FIG. 2 is pressed into the axial hole 51 of the main body 42. The right end of the pilot pin 63 in FIG. 2 is pressed into a recess 66 formed in the end face on the left side of the pilot body 62 in FIG. 2. A plurality of passages 67 (grooves) (only one shown in FIG. 2) extending in the axial direction (the "left-right direction" in FIG. 2) are formed on the outer peripheral surface of the right end of the pilot pin 63 in FIG. 2.

The pilot body 62 is formed in a generally bottomed cylindrical shape with an opening on the right side in FIG. 2. A flexible disk 69 is provided on the left end face of the pilot body 62 in FIG. 2, which is clamped by the inner periphery of the pilot body 62 and the large diameter portion 64 of the pilot pin 63. A cylindrical portion 70 is formed coaxially with the pilot body 62 on the outer periphery of the left end of the pilot body 62 in FIG. 2. The packing 46 of the main valve 41 is slidably abutted against the inner periphery of the cylindrical portion 70 (reference numeral omitted). As a result, a pilot chamber 71 is formed on the right side (back side) of the main disk 44 in FIG. 2. The pressure of the pilot chamber 71 acts on the main disk 44 in the valve closing direction (direction pressing against the seat portion 43).

The bottom of the pilot body 62 is provided with multiple axially extending passages 72 (only two are shown in FIG. 2) spaced at equal intervals in the circumferential direction. A flexible disk 69 is seated on an annular seat portion 73 provided on the left end face of the pilot body 62 in FIG. 2, forming an annular passage (reference numeral omitted) on the inside (inner circumference) of the seat portion 73. The left end of the passage 72 in FIG. 2 opens into this annular passage. The flexible disk 69 flexes under the internal pressure of the pilot chamber 71, imparting volumetric elasticity to the pilot chamber 71.

The flexible disk 69 is constructed by stacking multiple disks. The inner periphery of the flexible disk 69 is provided with a notch 75 that connects the passage 67 to the pilot chamber 71. As a result, the oil in the annular oil passage 21 is introduced into the damping force adjustment mechanism 31 via the flow path 36 (axial hole) of the joint member 28, and is introduced into the pilot chamber 71 via the introduction passage, i.e., the introduction orifice 65, the axial hole 76 of the pilot pin 63, the passage 67, and the notch 75 of the flexible disk 69.

A recess 77 opens on the right end face of the pilot body 62 in FIG. 2. An annular seat portion 79 (valve seat) is provided at the bottom of the recess 77, against which the valve body 78 can be seated and removed. The seat portion 79 is provided on the periphery of the opening of the recess 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 left end portion in FIG. 2 is formed in a tapered shape. An outer flange-shaped spring receiving portion 80 (see FIG. 3) is provided at the right end portion of the valve body 78 in FIG. 2. The valve body 78 is biased by the pilot spring 68 in a direction away from the seat portion 79 (to the right in FIG. 2).

A cylindrical portion 74 is formed at the end of the pilot body 62 on the right side in FIG. 2. As shown in FIG. 3, the pilot spring 68, spacer 93, failsafe disk 94, retainer 95, spacer 96, and washer 97 are stacked on the cylindrical portion 74 in this order from the left side in FIG. 3. As shown in FIG. 2, the stacked parts are fixed by a cap 98 fitted onto the outer periphery of the cylindrical portion 74. A passage 99 (notch, see FIG. 3) is formed in the cap 98, which connects the recess 77 (valve chamber) with the flow passage 35 on the outer periphery of the valve mechanism portion 33.

The solenoid 101, which functions as a variable damping force actuator of the damping force adjustment mechanism 31, is composed of a coil 102, a movable iron core 103, a fixed iron core 104, an overmold 105, an actuating rod 106, a pair of bushes 107, 108, a back pressure chamber forming member 131 (bush support member), a back pressure chamber 109, a cap member 141, etc. The solenoid 101 is, for example, a proportional solenoid.

The solenoid case 110 is formed in a cylindrical shape coaxial with the axis of the actuating rod 106 (the axis of the solenoid 101, hereafter referred to as the "axis"). The solenoid case 110 is formed as a substantially cylindrical yoke member made of a magnetic body (magnetic material) and forms a magnetic path when current is applied. The case 25 is fitted to the outer periphery of the end of the solenoid case 110 on the left side in FIG. 2 (inner side in the cylinder diameter direction). The gap between the solenoid case 110 and the case 25 is liquid-tightly sealed by a seal ring 111. The solenoid 110 and the case 25 are connected by multiple crimping parts 114 (only two are shown in FIG. 2) formed using a crimping jig (not shown).

The overmold 105 is inserted into the cylindrical portion 112 of the solenoid case 110. A seal ring 113 provides a liquid-tight seal between the opening of the cylindrical portion 112 and the overmold 105. The large diameter portion 142 of the cap member 141 is fitted into the inner flange portion 115 of the solenoid case 110. A seal ring 116 provides a liquid-tight seal between the inner flange portion 115 and the cap member 141.

The bobbin 117 that covers the coil 102 is provided on the outer periphery of the cap member 141. The bobbin 117 is formed from a resin material such as a thermosetting resin, and covers the inner periphery of the coil 102 by molding. The small diameter portion 144 of the cap member 141 is fitted into the open end of the bobbin 117 on the right side in FIG. 2. The insert core 118 is embedded in the inner periphery of the bobbin 117. Here, the inner diameter of the bobbin 117 and the inner diameter of the insert core 118 are approximately the same, and are set slightly larger than the outer diameter of the medium diameter portion 143 of the cap member 141.

The movable core 103 is disposed on the inner periphery of the cap member 141, and is fixed integrally to the actuation rod 106 so as to be movable in the axial direction. The movable core 103 is a so-called armature, and is formed, for example, in a cylindrical shape with a bottom, from an iron-based magnetic material. When magnetic force is generated by energizing the coil 102, the movable core 38 is attracted to the fixed core 104 and generates thrust. The outer diameter of the movable core 103 is formed slightly smaller than the inner diameter of the medium diameter portion 143 ("d2" in FIG. 5) of the cap member 141 so as to be able to move in the axial direction within the cap member 141.

The fixed core 104 is a so-called anchor, and is disposed on the inner periphery of the cap member 141. The fixed core 104 has a boss portion 119 through which the operating rod 106 is inserted, and a flange portion 120 formed on the left end of the boss portion 119 in FIG. 2. The fixed core 104 generates a magnetic force when the coil 102 is energized, thereby attracting the movable core 103 to the left in FIG. 2.

The right end face of the boss portion 119 in FIG. 2 is provided with a recess 121 into which the movable core 103 attracted to the fixed core 104 fits. The inner periphery of the fixed core 104 is provided with a bush fitting portion 122 into which the bush 108 supporting the operating rod 106 is fitted. The right end of the fixed core 104 in FIG. 2 is formed with a conical portion 123 having a tapered surface with a reduced diameter toward the movable core 103. The conical portion 123 functions to make the magnetic characteristics between the fixed core 104 and the movable core 103 linear.

The operating rod 106 is disposed on the inner periphery of the movable iron core 103, the fixed iron core 104, and the back pressure chamber forming member 131. The right end of the operating rod 106 in FIG. 2 is supported so as to be movable in the axial direction by a bush 107 press-fitted into the back pressure chamber forming member 131. A passage 124 is formed on the inner periphery of the operating rod 106, passing through the operating rod 106 in the axial direction and connecting the valve body 78 and the back pressure chamber forming member 131.

2 of the actuation rod 106 protrudes from the fixed iron core 104, and the valve body 78 of the valve mechanism 33 is fixed to the protruding end. That is, the valve body 78 is provided at the end of the actuation rod 106 on the fixed iron core 104 side, and moves (displaces) integrally with the movable iron core 103 and the actuation rod 106. In other words, the opening and opening pressure of the valve body 78 correspond to the thrust of the movable iron core 103 based on the energization of the coil 102. That is, the pilot valve 61 of the valve mechanism 33 is opened and closed by the axial movement of the movable iron core 103.

The back pressure chamber forming member 131 (bush support member) is made of a non-magnetic body (non-magnetic material), and the cross section taken along a plane perpendicular to the axis is formed by concentric circles. The back pressure chamber forming member 131 relatively reduces the pressure acting on the valve body 78 when the back pressure chamber 109 is filled with the working fluid that has flowed in through the passage 124 of the working rod 106. The back pressure chamber 109 is formed by a space defined by a back pressure chamber forming portion 140 (recess, see FIG. 4) of the back pressure chamber forming member 131, the working rod 106, and the bush 107, which will be described later. The pressure receiving area of the back pressure chamber 109 is set to be smaller than the pressure receiving area when the valve body 78 receives hydraulic force between the valve seat 79.

As shown in FIG. 4, a concave bush press-in portion 133 into which the bush 107 is press-fitted is opened on the end face 132 of the back pressure chamber forming member 131 on the movable core 103 side (the "left side" in FIG. 2). A concave back pressure chamber forming portion 140 into which the operating rod 106 protrudes is opened on the annular bottom portion 134 of the bush press-in portion 133. The inner peripheral surfaces of the bush press-in portion 133 and the back pressure chamber forming portion 140 are cylindrical surfaces (with a constant inner diameter), and the inner diameter of the back pressure chamber forming portion 140 is smaller than the inner diameter of the bush press-in portion 133.

A large outer diameter portion 135 having a cylindrical surface is formed on the movable core 103 side ("left side" in Figs. 2 and 4) of the back pressure chamber forming member 131. A small outer diameter portion 136 having a cylindrical surface is formed on the opposite side of the movable core 103 side ("right side" in Figs. 2 and 4) of the back pressure chamber forming member 131. The large outer diameter portion 135 and the small outer diameter portion 136 are smoothly connected via a tapered portion 137 having a small gradient with respect to the axis. An outer R portion 139 is formed at the ridge between the small outer diameter portion 136 and the abutment surface 138 opposite the end surface 132. The R dimension of the outer R portion 139 is set larger than the R dimension of the inner R portion 145 of the small diameter portion 144 (bottom) of the cap member 141. This prevents the outer R portion 139 of the back pressure chamber forming member 131 from interfering with the inner R portion 145 of the bottom of the cap member 141.

2, the cap member 141 is provided to surround the movable iron core 103, the fixed iron core 104, the back pressure chamber forming member 131, etc. Referring to FIG. 5, the cap member 141 is formed into a stepped cylindrical shape with a bottom from a thin plate made of a non-magnetic material. The cap member 141 is arranged, in order from the left in FIG. 5, with a large diameter portion 142, a medium diameter portion 143, and a small diameter portion 144 (bottom). The large diameter portion 142 is arranged on the outer periphery of the boss portion 119 of the fixed iron core 104 so as to face the boss portion 119 in the radial direction. The medium diameter portion 143 is arranged on the outer periphery of the movable iron core 103 so as to face the movable iron core 103 in the radial direction.

A flange portion 152 is formed on the periphery of the opening of the large diameter portion 142. The flange portion 152 is clamped by the flange portion 120 of the fixed core 104 and the inner flange portion 115 of the solenoid case 110. A tapered portion 146 is formed between the large diameter portion 142 and the medium diameter portion 143. The tapered portion 146 is disposed with a certain gap between it and the conical portion 123 of the fixed core 104. The medium diameter portion 143 and the small diameter portion 144 (bottom) are smoothly connected via a tapered portion 147 that has a small gradient with respect to the axis.

A large inner diameter portion 148 is formed on the inner circumference of the large diameter portion 142, into which the boss portion 119 of the fixed core 104 is fitted. A medium inner diameter portion 149 is formed on the inner circumference of the medium diameter portion 143, into which the movable core 103 is slidably fitted. A small inner diameter portion 150 is formed on the inner circumference of the small diameter portion 144 (bottom), into which the back pressure chamber forming member 131 (bush support member) is press-fitted. In addition, a bottom surface 151 is formed on the bottom of the small diameter portion 144, against which the abutment surface 138 of the back pressure chamber forming member 131 (small outer diameter portion 136) abuts.

Here, the inner diameter d2 (see FIG. 5) of the medium inner diameter portion 149 of the cap member 141 is set slightly larger than the inner diameter d1 (see FIG. 5) of the small inner diameter portion 150 (d2>d1). On the other hand, the outer diameter D1 (see FIG. 4) of the large outer diameter portion 135 of the back pressure chamber forming member 131 is set slightly smaller than the inner diameter d2 of the medium inner diameter portion 149 of the cap member 141 (d2>D1). As a result, the back pressure chamber forming member 131 is guided by the medium inner diameter portion 149 of the cap member 141 during press-fitting, and can move axially relative to the cap member 141.

The outer diameter D2 (see FIG. 4) of the small outer diameter portion 136 of the back pressure chamber forming member 131 is set to be slightly smaller than the inner diameter d1 (see FIG. 5) of the small inner diameter portion 150 of the cap member 141 (d1>D2). As a result, when the back pressure chamber forming member 131 is fitted (pressed) into the small diameter portion 144 (bottom) of the cap member 141, the fit between the small outer diameter portion 136 of the back pressure chamber forming member 131 and the small inner diameter portion 150 of the cap member 141 is a clearance fit. On the other hand, the fit between the large outer diameter portion 135 of the back pressure chamber forming member 131 and the small inner diameter portion 150 of the cap member 141 is an interference fit.

When the coil 102 is not energized, the valve body 78 is urged to the right in FIG. 2 (outward in the cylinder diameter direction) by the pilot spring 68, 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 102 is energized, a thrust force is generated in the movable iron core 103 in the left direction in FIG. 2. This causes the operating rod 59 to move to the left in FIG. 2 (inward in the cylinder diameter direction) against the biasing force of the pilot spring 68. In the soft mode, in which the current value of the current applied to the coil 102 is small, the biasing force of the pilot spring 68 and the thrust of the movable iron core 103 are balanced, and the pilot valve 61 opens to a constant valve opening amount (valve opening amount during soft characteristics).

During the extension stroke, the disk valve 14 of the piston 5 closes due to the pressure rise in the cylinder upper chamber 2A, and before the disk valve 13 opens, the hydraulic fluid in the cylinder upper chamber 2A is pressurized. The pressurized hydraulic fluid is introduced into the damping force adjustment mechanism 31 via the passage 22, the annular flow path 21, the connection port 23, and the joint member 28. At this time, the hydraulic fluid moved by the piston 5 flows from the reservoir 4 to the cylinder lower chamber 2B by opening the disk valve 17 of the base valve 10. When the pressure in the cylinder upper chamber 2A reaches the opening pressure of the disk valve 13 of the piston 5 and the disk valve 13 opens, the pressure in the cylinder upper chamber 2A is relieved to the cylinder lower chamber 2B. This prevents excessive pressure rise in the cylinder upper chamber 2A.

During the compression stroke, the pressure rises in the cylinder lower chamber 2B, opening the disc valve 14 of the piston 5, and closing the disc valve 17 of the extension passage 15 of the base valve 10. Before the disc valve 18 opens, the hydraulic fluid in the piston lower chamber 2B flows into the cylinder upper chamber 2A, and the hydraulic fluid equivalent to the volume of the piston rod 6 that has entered the cylinder 2 is introduced from the cylinder upper chamber 2A through the passage 22, the annular passage 21, the connection port 23, and the passage 36 to the damping force adjustment mechanism 31. When the pressure in the cylinder lower chamber 2B reaches the opening pressure of the disc valve 18 of the base valve 10 and the disc valve 18 opens, the pressure in the cylinder lower chamber 2B is relieved to the reservoir 4. This prevents excessive pressure rise in the cylinder lower chamber 2B.

The hydraulic fluid introduced into the damping force adjustment mechanism 31 passes through the inlet orifice 65, the shaft hole 76, the recess 77, and the passage 72, and is introduced into the pilot chamber 71 by opening the flexible disk 69. Before the main valve 41 opens (when the piston speed is in the low speed range), the hydraulic fluid that has flowed into the recess 77 flows to the reservoir 4 through the pilot spring 68, the failsafe disk 94, the washer 97, the passage 99, the flow path 35 on the outer periphery of the valve mechanism 33, and the multiple passages 27 formed in the inner flange portion 26 of the case 25.

When the pressure of the hydraulic fluid introduced into the annular passage 48 via the annular oil passage 21, the flow passage 36, and the passage 50 reaches the opening pressure of the main valve 41 due to an increase in piston speed, and the main valve 41 opens, the hydraulic fluid introduced into the annular passage 48 flows to the reservoir 4 via the flow passage 35 on the outer periphery of the valve mechanism 33 and the multiple passages 27 formed in the inner flange portion 26 of the case 25.

In this way, during both the extension stroke and compression stroke of the piston rod 6, before the main valve 41 opens (when the piston speed is in the low-speed range), the damping force adjustment mechanism 31 generates a damping force by passing the hydraulic fluid through the inlet orifice 65 and the pilot valve 61. After the main valve 41 opens (when the piston speed is in the medium-speed range), a damping force is generated according to the opening degree of the main valve 41. At this time, the damping force generated by the damping force adjustment mechanism 31 can be directly controlled by controlling the current supply to the coil 102 to adjust the opening pressure of the pilot valve 61.

If thrust from the movable core 103 is lost due to a failure such as a break in the coil 102 or a malfunction of the on-board controller, the biasing force of the pilot spring 68 (which also serves as a fail-safe spring) moves the valve body 78 to the right in FIG. 2, opening the pilot valve 61. In addition, the spring receiving portion 80 of the valve body 78 is brought into contact with the fail-safe disk 94, blocking communication between the flow path (reference number omitted) inside the valve mechanism 33 and the flow path 35 outside the valve mechanism 33.

By adjusting the opening pressure of the fail-safe valve 91 and controlling the flow of hydraulic fluid from the annular oil passage 21 to the reservoir 4 via the flow passage 36 of the joint member 28, the introduction orifice 65 of the pilot pin 63, the axial hole 76, the recess 77 of the pilot body 62, the axial hole of the washer 97, the passage 99 (notch) formed in the cap 98, the flow passage 35 on the outer periphery of the valve mechanism 33, and the multiple passages 27 formed in the inner flange portion 26 of the case 25, a constant damping force can be generated even when a failure occurs. At the same time, it is possible to adjust the internal pressure of the pilot chamber 71 and therefore the opening pressure of the main valve 41, and to obtain a constant damping force even when a failure occurs.

In conventional damping force adjustment mechanisms, when the backpressure chamber forming member is pressed into the small diameter portion (bottom) of the cap member during the manufacturing process of the solenoid, if the axis of the backpressure chamber forming member is inclined with respect to the axis of the cap member, the abutment surface of the backpressure chamber forming member (the end surface opposite the movable core side) cannot abut (make surface contact with) the bottom surface of the cap member, and the press-in depth of the backpressure chamber forming member becomes shallow.
In this case, the axial movement of the actuating rod during the fail-safe state is restricted by the movable iron core hitting the back pressure chamber forming member, so that the movement of the actuating rod during the fail-safe state is stopped before the spring receiving portion of the valve body seats on the fail-safe disk. As a result, the actuating fluid flows through the gap between the valve body and the fail-safe disk, and the damping force during the fail-safe state is reduced.

In contrast to this, in the present embodiment, a large outer diameter portion 135 is formed on the valve body 78 side (movable core 103 side) of the back pressure chamber forming member 131 (bush support member), and a small outer diameter portion 136 is formed on the bottom surface 151 side of the cap member 141 of the back pressure chamber forming member 131, and the large outer diameter portion 135 and the small outer diameter portion 136 are connected by a gentle tapered portion 137.
The large outer diameter portion 135 of the back pressure chamber forming member 131 and the small inner diameter portion 150 of the small diameter portion 144 (bottom) of the cap member 141 are fitted together by an interference fit, and the small outer diameter portion 136 of the back pressure chamber forming member 131 and the small inner diameter portion 150 of the cap member 141 are fitted together by a clearance fit.
Therefore, in this embodiment, during the manufacturing process of the solenoid 101, when the back pressure chamber forming member 131 (bush support member) is pressed into the small diameter portion 144 (bottom) of the cap member 141, first, the small outer diameter portion 136 of the back pressure chamber forming member 131 is inserted into the small inner diameter portion 150 of the cap member 141.
At this time, the fit between the small outer diameter portion 136 of the back pressure chamber forming member 131 and the small inner diameter portion 150 of the cap member 141 is a clearance fit, so that the back pressure chamber forming member 131 can be prevented from tilting relative to the cap member 141 (small diameter portion 144) due to the small outer diameter portion 136 being gouged out by the small inner diameter portion 150, for example.
Thereafter, the back pressure chamber forming member 131 is guided by the tapered portion 137 and the small inner diameter portion 150 of the cap member 141, so that the large outer diameter portion 135 of the back pressure chamber forming member 131 is press-fitted into the small inner diameter portion 150 of the cap member 141 while maintaining the coaxiality of the back pressure chamber forming member 131 and the cap member 141. This allows the back pressure chamber forming member 131 to be press-fitted into the cap member 141 until the abutment surface 138 of the back pressure chamber forming member 131 abuts against (comes into surface contact with) the bottom surface 151 of the cap member 141.
According to this embodiment, in the fail-safe state, the spring receiving portion 80 of the valve body 78 can be reliably seated on the fail-safe disk 94, and a decrease in the damping force in the fail-safe state can be prevented.
Furthermore, according to this embodiment, coaxiality is ensured between the cap member 141 and the bush 107 held in the back pressure chamber forming member 131, and by extension, coaxiality is ensured between the bush 107 and the bush 108 held in the fixed iron core 104, so that it is possible to reduce the sliding resistance between the operating rod 106 and the bushes 107, 108 and improve the hysteresis characteristics of the solenoid 101.
Furthermore, since the axis of the back pressure chamber forming member 131 and the axis of the cap member 141 are prevented from tilting during press-fitting, it is possible to prevent the back pressure chamber forming member 131 from being scratched or deformed during press-fitting.

1 Damping force adjustable shock absorber, 2 Cylinder, 5 Piston, 6 Piston rod, 31 Damping force adjustment mechanism, 36 Flow path, 78 Valve body, 101 Solenoid, 102 Coil, 103 Movable core, 104 Fixed core, 107, 108 Bush, 131 Back pressure chamber forming member (bush support member), 135 Large outer diameter portion, 136 Small outer diameter portion, 141 Cap member, 144 Small diameter portion (bottom), 148 Large inner diameter portion, 150 Small inner diameter portion, 151 Bottom surface

Claims (4)

A cylinder in which a working fluid is sealed;
A piston that is fitted in the cylinder and divides the inside of the cylinder into two chambers;
a piston rod having one end connected to the piston and the other end protruding to the outside through an opening of the cylinder;
a flow path in which a flow of a working fluid occurs as the piston rod expands and contracts;
a damping force adjustment mechanism provided in the flow path, the damping force adjustment mechanism adjusting a valve opening pressure by a thrust generated by a solenoid,
The solenoid is
A coil that generates magnetic force when energized;
a bottomed cylindrical cap member disposed on an inner circumferential side of the coil;
a movable core disposed on an inner circumferential side of the cap member and movable in an axial direction;
a fixed core arranged axially opposite to the movable core and attracting the movable core;
a bushing support member having a bottom and a cylindrical shape that is fitted to a bottom portion of the cap member;
A pair of bushes disposed on the inner circumferential side of the bush support member and the fixed core;
an actuation rod supported by the pair of bushes so as to be movable in the axial direction;
a valve body of the damping force adjustment mechanism is provided at an end of the actuation rod on the fixed core side,
the cap member has a large inner diameter portion into which an end portion of the fixed core facing the movable core is fitted, and a small inner diameter portion into which the bush support member is press-fitted,
the bush support member has a large outer diameter portion formed on the valve body side, a small outer diameter portion formed on a bottom surface side of the cap member, and a tapered portion connecting the large outer diameter portion and the small outer diameter portion ,
4. A shock absorber with adjustable damping force, comprising: a cap member having a bottom surface on which a chamfer is formed; and a cap member having a bottom surface on which a chamfer is formed . 2. The damping force control shock absorber according to claim 1,
A damping force adjustable shock absorber characterized in that the bush support member has a bush press-in portion that opens on the valve body side and into which the bush is press-in, and a recess that opens at the bottom of the press-in portion and into which the operating rod protrudes. 3. The damping force control shock absorber according to claim 1 or 2,
2. A shock absorber with adjustable damping force, comprising: a tapered portion formed between the large outer diameter portion and the small outer diameter portion of the bush support member. A coil that generates magnetic force when energized;
a bottomed cylindrical cap member disposed on an inner circumferential side of the coil;
a movable core disposed on an inner circumferential side of the cap member and movable in an axial direction;
a fixed core arranged axially opposite to the movable core and attracting the movable core;
a bushing support member having a bottom and a cylindrical shape that is fitted to a bottom portion of the cap member;
A pair of bushes disposed on the inner circumferential side of the bush support member and the fixed core;
an actuation rod supported by the pair of bushes so as to be movable in the axial direction;
the cap member has a large inner diameter portion into which an end portion of the fixed core facing the movable core is fitted, and a small inner diameter portion into which the bush support member is press-fitted,
the bush support member has a large outer diameter portion formed on the fixed core side, a small outer diameter portion formed on a bottom surface side of the cap member, and a tapered portion connecting the large outer diameter portion and the small outer diameter portion ,
A solenoid , wherein the small outer diameter portion has a chamfer formed on a bottom side of the cap member .

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