Solenoid, damping force adjustment mechanism, and damping force adjustable shock absorber

Abstract

Provided are a solenoid that can both ensure thrust for a movable element (movable iron core) and prevent vibration, a damping force adjustment mechanism, and a damping force adjustable shock absorber.　The solenoid comprises a coil, an armature, an anchor, and an actuation pin. The coil generates a magnetic field by being energized. At least a portion of the armature is on the inner circumferential side of the coil and is provided movably in the axial direction. The anchor faces the armature in the axial direction. The actuation pin is displaced integrally with the armature. The armature has a large diameter portion and a small diameter portion. In this case, the small diameter portion is provided on the anchor side.

Description

Technical Field

[0001] The present disclosure relates to, for example, a solenoid, a damping force adjusting mechanism, and a damping force adjustable shock absorber.

Background Art

[0002] A vehicle such as a four-wheel automobile is provided with a shock absorber (damper) between the vehicle body (above the spring) side and each wheel (below the spring) side. As such a shock absorber for a vehicle, for example, a damping force adjustable hydraulic shock absorber that variably adjusts the damping force according to driving conditions, vehicle behavior, etc. is known. The damping force adjustable hydraulic shock absorber constitutes a semi-active suspension of the vehicle.

[0003] The damping force adjustable hydraulic shock absorber variably adjusts the generated damping force, for example, by adjusting the opening pressure of a damping force adjusting valve with a damping force variable actuator. As the damping force variable actuator, for example, a solenoid is used. Here, for example, Patent Document 1 describes a solenoid provided with a notch portion that becomes a non-uniform portion in the circumferential direction of the mover by cutting the mover (movable iron core) diagonally. According to this solenoid, the mover is biased to an arbitrary position in the circumferential direction, and a non-uniform force in the circumferential direction is applied to the bearing. Thereby, the sway and vibration of the mover are suppressed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] When a notch is formed at a position where the mover (movable iron core) and the stator (fixed iron core) face each other, the attractive force (thrust of the mover) between the mover and the stator decreases, and there is a possibility that the mover becomes difficult to move particularly at low current.

[0006] An object of one embodiment of the present invention is to provide a solenoid, a damping force adjustment mechanism, and a damping force adjustable shock absorber that can achieve both securing the thrust of a movable element (movable iron core) and suppressing vibration. [Means for solving the problem]

[0007] One embodiment of the present invention is a solenoid comprising: a coil that generates a magnetic field when energized; a movable core that is at least a portion of which is located on the inner circumference side of the coil and is movable in the axial direction of the coil; a fixed core that faces the movable core in the axial direction and has a cylindrical outer peripheral projection that protrudes toward the movable core; a magnetic member disposed between the inner circumference side of the coil and the movable core and having a first end facing the outer peripheral projection; and a shaft that displaces integrally with the movable core, wherein the movable core has a large diameter portion and a small diameter portion, the small diameter portion is provided toward the fixed core side, the axial length of the large diameter portion is formed to be smaller than the axial length of the small diameter portion, the axial length of the small diameter portion is formed to be longer than the distance from the axial end on the fixed core side to the first end when the coil is energized, and the gap between the outer circumference of the large diameter portion and the inner circumference of the magnetic member is formed to be smaller than the gap between the outer circumference of the small diameter portion and the inner circumference of the fixed core. The large diameter portion has an axially elongated portion (L1) that extends in the axial direction. It is.

[0009] Furthermore, one embodiment of the present invention is a damping force adjustable shock absorber, the damping force adjustable shock absorber comprising: a cylinder in which a working fluid is sealed; a piston inserted into the cylinder and dividing the inside of the cylinder into a rod side chamber and a bottom side chamber; a piston rod, one end of which is connected to the piston and the other end of which extends to the outside of the cylinder; a flow path through which the working fluid flows as the piston rod expands and contracts; and a damping force adjustment valve provided in the flow path and driven by a solenoid, wherein the solenoid comprises: a coil that generates a magnetic field when energized; a movable iron core, at least a portion of which is on the inner circumference side of the coil and is provided to be movable in the axial direction of the coil; and the movable iron The device comprises a fixed core facing the core in the axial direction and having a cylindrical outer circumferential projection that protrudes toward the movable core, and a magnetic member disposed between the inner circumference of the coil and the movable core, with a first end facing the outer circumferential projection, wherein the movable core has a large diameter portion and a small diameter portion, the small diameter portion is provided toward the fixed core, the axial length of the large diameter portion is formed to be smaller than the axial length of the small diameter portion, the axial length of the small diameter portion is formed to be longer than the distance from the axial end on the fixed core side to the first end when the coil is energized, and the gap between the outer circumference of the large diameter portion and the inner circumference of the magnetic member is formed to be smaller than the gap between the outer circumference of the small diameter portion and the inner circumference of the fixed core. The large diameter portion has an axially elongated portion (L1) that extends in the axial direction. It is.

[0010] Furthermore, one embodiment of the present invention is a damping force adjustment mechanism comprising: a coil that generates a magnetic field when energized; a movable element located on the inner circumference side of the coil and movably mounted in the axial direction; a stator facing the movable element in the axial direction and having a cylindrical outer peripheral projection that protrudes toward the movable element; a control valve controlled by the axial movement of the movable element; and a magnetic member disposed between the inner circumference side of the coil and the movable element and having a first end facing the outer peripheral projection, wherein the movable element has a large diameter portion and a small diameter portion, the small diameter portion is provided on the stator side, the axial length of the large diameter portion is formed to be smaller than the axial length of the small diameter portion, the axial length of the small diameter portion is formed to be longer than the distance from the axial end on the stator side to the first end when the coil is energized, and the gap between the outer circumference of the large diameter portion and the inner circumference of the magnetic member is formed to be smaller than the gap between the outer circumference of the small diameter portion and the inner circumference of the stator. The large diameter portion has an axially elongated portion (L1) that extends in the axial direction. It is.

[0012] According to one embodiment of the present invention, it is possible to achieve both securing the thrust of the movable core (movable element) and suppressing vibration. [Brief explanation of the drawing]

[0013] [Figure 1] This is a longitudinal cross-sectional view showing a damping force adjustable shock absorber incorporating a solenoid and a damping force adjustment mechanism according to an embodiment. [Figure 2] This is an enlarged cross-sectional view showing the damping force adjustment valve and solenoid extracted from Figure 1. [Figure 3] This is an enlarged cross-sectional view showing the solenoid extracted from Figure 1. [Figure 4] This is an enlarged cross-sectional view of (IV) in Figure 1. [Figure 5] This is an enlarged cross-sectional view of the same position as Figure 4, showing a solenoid according to the first modified example. [Figure 6] This is an enlarged cross-sectional view of the same position as in Figure 4, showing a solenoid according to a second modification. [Figure 7] This is an enlarged cross-sectional view of the same position as in Figure 4, showing a solenoid according to a third modification. [Figure 8]This is a longitudinal cross-sectional view showing a movable core (movable element) according to the fourth to sixth modified example. [Figure 9] These are a longitudinal section view and a bottom view showing the movable core (movable element) according to the seventh and eighth modified examples. [Modes for carrying out the invention]

[0014] The following description will use the solenoid, damping force adjustment mechanism, and damping force adjustable shock absorber according to the embodiment as an example when used in a damping force adjustable hydraulic shock absorber, with reference to the attached drawings.

[0015] Figures 1 to 4 show embodiments. In Figure 1, the damping force adjustable hydraulic shock absorber 1 (hereinafter referred to as shock absorber 1) is equipped with a damping force adjustment mechanism 17 driven by a solenoid 33. That is, the shock absorber 1 as a damping force adjustable shock absorber is composed of an outer cylinder 2 and an inner cylinder 4 as cylinders, a piston 5, a piston rod 8, a rod guide 9, and a damping force adjustment mechanism 17.

[0016] The shock absorber 1, which is a hydraulic shock absorber, has a bottomed cylindrical outer cylinder 2 that forms the outer shell. The lower end of the outer cylinder 2 is closed by a bottom cap 3 using welding or the like. The upper end of the outer cylinder 2 is a crimped portion 2A that is bent radially inward. A rod guide 9 and a sealing member 10 are provided between the crimped portion 2A and the inner cylinder 4. On the other hand, an opening 2B is formed on the lower side of the outer cylinder 2, concentric with the connection port 12C of the intermediate cylinder 12. A damping force adjustment mechanism 17 is attached to the lower side of the outer cylinder 2, facing the opening 2B. The bottom cap 3 is provided with a mounting eye 3A, which is attached to the wheel side of the vehicle, for example.

[0017] An inner cylinder 4 is provided inside the outer cylinder 2, coaxially with the outer cylinder 2. The lower end of the inner cylinder 4 is fitted and attached to the bottom valve 13. The upper end of the inner cylinder 4 is fitted and attached to the rod guide 9. An oily liquid is sealed inside the outer cylinder 2 and inner cylinder 4, which function as cylinders, as a working fluid. The working fluid is not limited to oily liquid or oil; for example, water mixed with additives may also be used.

[0018] An annular reservoir chamber A is formed between the inner cylinder 4 and the outer cylinder 2. Gas is enclosed in the reservoir chamber A together with the oil. This gas may be air in an atmospheric pressure state, or a gas such as compressed nitrogen gas may be used. The reservoir chamber A compensates for the entry and exit of the piston rod 8. An oil hole 4A for constantly communicating the rod-side oil chamber B with the annular oil chamber D is drilled in the middle position in the length direction (axial direction) of the inner cylinder 4 in the radial direction.

[0019] The piston 5 is provided slidably in the inner cylinder 4. The piston 5 is inserted into the inner cylinder 4 and divides the inside of the inner cylinder 4 into two chambers, namely, the rod-side oil chamber B (rod-side chamber) and the bottom-side oil chamber C (bottom-side chamber). A plurality of oil passages 5A and 5B for communicating the rod-side oil chamber B and the bottom-side oil chamber C are formed at intervals in the circumferential direction on the piston 5.

[0020] Here, an extension-side disk valve 6 is provided on the lower end surface of the piston 5. The extension-side disk valve 6 opens when the pressure in the rod-side oil chamber B exceeds the relief setting pressure when the piston 5 slides upward during the extension stroke of the piston rod 8, and at this time, the pressure is relieved to the bottom-side oil chamber C side through each oil passage 5A. The relief setting pressure is set to a pressure higher than the opening pressure when the damping force adjustment mechanism 17 is set hard.

[0021] A contraction-side check valve 7 that opens when the piston 5 slides downward during the contraction stroke of the piston rod 8 and closes otherwise is provided on the upper end surface of the piston 5. The check valve 7 allows the oil in the bottom-side oil chamber C to flow through each oil passage 5B toward the rod-side oil chamber B, and blocks the oil from flowing in the reverse direction. The opening pressure of the check valve 7 is set to a pressure lower than the opening pressure when the damping force adjustment mechanism 17 is set soft, and substantially no damping force is generated. This substantially no damping force means a force below the friction of the piston 5 and the seal member 10 and has no influence on the movement of the vehicle.

[0022] The piston rod 8 extends axially (up and down in Figure 1) within the inner cylinder 4. The lower end of the piston rod 8 is inserted into the inner cylinder 4. The piston rod 8 is fixed to the piston 5 by a nut 8A or the like. The upper end of the piston rod 8 protrudes to the outside of the outer cylinder 2 and inner cylinder 4 via a rod guide 9. That is, the lower end of the piston rod 8 is connected to the piston 5, and the upper end extends to the outside of the inner cylinder 4 and outer cylinder 2. Alternatively, the lower end of the piston rod 8 may be further extended to protrude outward from the bottom (for example, the bottom cap 3), creating a so-called double rod.

[0023] A stepped cylindrical rod guide 9 is provided on the upper end of the inner cylinder 4. The rod guide 9 positions the upper portion of the inner cylinder 4 in the center of the outer cylinder 2 and guides the piston rod 8 so that it can slide in the axial direction on its inner circumference. An annular sealing member 10 is provided between the rod guide 9 and the crimped portion 2A of the outer cylinder 2. The sealing member 10 is constructed, for example, by baking an elastic material such as rubber onto a metal ring plate with a hole in the center through which the piston rod 8 is inserted. The sealing member 10 seals the space between itself and the piston rod 8 by the inner circumference of the elastic material sliding against the outer circumference of the piston rod 8.

[0024] The sealing member 10 has a lip seal 10A formed on its lower surface, which acts as a check valve and extends to contact the rod guide 9. The lip seal 10A is positioned between the oil reservoir chamber 11 and the reservoir chamber A. The lip seal 10A allows the oil liquid in the oil reservoir chamber 11 to flow toward the reservoir chamber A through the return passage 9A of the rod guide 9, while preventing reverse flow.

[0025] An intermediate cylinder 12, made of a cylindrical body, is disposed between the outer cylinder 2 and the inner cylinder 4. The intermediate cylinder 12 is attached, for example, to the outer circumference of the inner cylinder 4 via upper and lower cylindrical seals 12A and 12B. The intermediate cylinder 12 forms an annular oil chamber D inside, which extends to surround the entire outer circumference of the inner cylinder 4. The annular oil chamber D is an oil chamber independent of the reservoir chamber A. The annular oil chamber D is in constant communication with the rod-side oil chamber B through a radial oil hole 4A formed in the inner cylinder 4. The annular oil chamber D constitutes a flow path through which the working fluid is generated by the movement of the piston rod 8. A connection port 12C is provided at the lower end of the intermediate cylinder 12, to which the connecting pipe 20 of the damping force adjustment valve 18 is attached.

[0026] The bottom valve 13 is located on the lower end side of the inner cylinder 4 and is provided between the bottom cap 3 and the inner cylinder 4. The bottom valve 13 consists of a valve body 14 that separates (partitions) the reservoir chamber A and the bottom oil chamber C between the bottom cap 3 and the inner cylinder 4, a retractable disc valve 15 provided on the lower side of the valve body 14, and an extension check valve 16 provided on the upper side of the valve body 14. The valve body 14 has oil passages 14A and 14B formed in it at circumferential intervals, allowing communication between the reservoir chamber A and the bottom oil chamber C.

[0027] The retracting disc valve 15 opens when the pressure in the bottom oil chamber C exceeds the relief setting pressure when the piston 5 slides downward during the retraction stroke of the piston rod 8, and relieves this pressure to the reservoir chamber A via each oil passage 14A. The relief setting pressure is set to a higher pressure than the valve opening pressure when the damping force adjustment mechanism 17 is set to hard.

[0028] The extension-side check valve 16 opens when the piston 5 slides upward during the extension stroke of the piston rod 8, and closes at all other times. The check valve 16 allows the oil in the reservoir chamber A to flow through each oil passage 14B toward the bottom-side oil chamber C, and prevents the oil from flowing in the opposite direction. The opening pressure of the check valve 16 is set to a pressure lower than the opening pressure when the damping force adjustment mechanism 17 is set to soft, and thus does not generate any damping force.

[0029] Next, the damping force adjustment mechanism 17 for variably adjusting the damping force generated by the shock absorber 1 will be explained, referring to both Figure 1 and Figure 2.

[0030] The damping force adjustment mechanism 17 controls the flow of the working fluid generated by the sliding of the piston 5 inside the cylinder (inner cylinder 4) to generate damping force, and is a mechanism that variably adjusts the damping force generated by the shock absorber 1. In Figure 2, the damping force adjustment mechanism 17 is shown in a state where the armature 48 (actuating pin 49) has moved to the left side of Figure 2 (i.e., in the closed direction where the pilot valve body 32 sits on the valve seat portion 26E of the pilot body 26) by externally energizing the coil 34A of the solenoid 33 (for example, controlling to generate a hard damping force).

[0031] As shown in Figure 1, the damping force adjustment mechanism 17 is positioned with its base end (left end in Figure 1) interposed between the reservoir chamber A and the annular oil chamber D, and its tip end (right end in Figure 1) protrudes radially outward from the lower side of the outer cylinder 2. The damping force adjustment mechanism 17 generates damping force by controlling the flow of oil from the annular oil chamber D to the reservoir chamber A using the damping force adjustment valve 18. Furthermore, the generated damping force is variably adjusted by adjusting the opening pressure of the damping force adjustment valve 18 with a solenoid 33 used as a variable damping force actuator. In this way, the damping force adjustment mechanism 17 generates damping force by controlling the flow of working fluid (oil) generated by the sliding of the piston 5 inside the inner cylinder 4.

[0032] In other words, the damping force adjustment mechanism 17 comprises a damping force adjustment valve 18 and a solenoid 33. The damping force adjustment valve 18 generates a damping force with hard or soft characteristics by variably controlling the flow of oil from the annular oil chamber D to the reservoir chamber A. The damping force adjustment valve 18 is driven by the solenoid 33. In other words, the damping force adjustment valve 18 is a valve whose opening and closing operation is adjusted by the solenoid 33, and is installed in a flow path (for example, between the annular oil chamber D and the reservoir chamber A) where the flow of working fluid is generated by the movement (extension and contraction) of the piston rod 8. The solenoid 33 adjusts the opening and closing operation of the damping force adjustment valve 18. In other words, the opening pressure of the damping force adjustment valve 18 is adjusted by the solenoid 33, which is used as a variable damping force actuator, thereby variably controlling the generated damping force to have hard or soft characteristics.

[0033] Here, the damping force adjustment valve 18 is composed of a substantially cylindrical valve case 19 whose base end is fixed around the opening 2B of the outer cylinder 2 and whose tip end protrudes radially outward from the outer cylinder 2, a connecting pipe body 20 whose base end is fixed to the connection port 12C of the intermediate cylinder 12 and whose tip end is an annular flange portion 20A and is disposed inside the valve case 19 with a gap, and a valve member 21 that abuts against the flange portion 20A of the connecting pipe body 20.

[0034] As shown in Figure 2, the base end of the valve case 19 has an annular inner flange portion 19A that extends radially inward. The tip end of the valve case 19 has a male threaded portion 19B to which a lock nut 53 is screwed, connecting the valve case 19 to the yoke 39 (one side cylindrical portion 39G) of the solenoid 33. The space between the inner circumferential surface of the valve case 19 and the outer circumferential surface of the valve member 21, and further, the space between the inner circumferential surface of the valve case 19 and the outer circumferential surface of the pilot body 26, etc., is an annular oil chamber 19C that is in constant communication with the reservoir chamber A. Note that in addition to connecting the valve case 19 and the solenoid 33 with the lock nut 53, the valve case 19 and the solenoid 33 may also be connected in a configuration where, for example, the tip end of the valve case is crimped to the yoke of the solenoid (a configuration without using a lock nut).

[0035] The inside of the connecting pipe 20 has an oil passage 20B on one side that communicates with the annular oil chamber D and on the other side that extends to the position of the valve member 21. An annular spacer 22 is provided sandwiched between the flange portion 20A of the connecting pipe 20 and the inner flange portion 19A of the valve case 19. Multiple notches 22A are provided radially on the spacer 22, forming radial oil passages that connect the oil chamber 19C and the reservoir chamber A. In this embodiment, the spacer 22 is configured to have notches 22A for forming oil passages. However, instead of the spacer 22, notches (grooves) for forming oil passages may be provided radially on the inner flange portion 19A of the valve case 19. By configuring it this way, the spacer 22 can be omitted and the number of parts can be reduced.

[0036] The valve member 21 is provided with a central hole 21A located at the radial center and extending axially. The valve member 21 also has multiple oil passages 21B spaced circumferentially around the central hole 21A. One side of each oil passage 21B (the left side in Figures 1 and 2) is constantly in communication with the oil passage 20B side of the connecting pipe 20. The other end face of the valve member 21 (the right side in Figures 1 and 2) is provided with an annular recess 21C formed to surround the other opening of the oil passage 21B, and an annular valve seat 21D located radially outside the annular recess 21C, on which the main valve 23 sits and unseats. Here, each oil passage 21B of the valve member 21 becomes a flow path through which pressurized oil flows at a flow rate corresponding to the opening degree of the main valve 23 between the oil passage 20B of the connecting pipe 20, which communicates with the annular oil chamber D, and the oil chamber 19C of the valve case 19, which communicates with the reservoir chamber A.

[0037] The main valve 23 is composed of a disc valve whose inner circumference is sandwiched between the valve member 21 and the large-diameter portion 24A of the pilot pin 24. The outer circumference of the main valve 23 seats away from the annular valve seat 21D of the valve member 21. An elastic seal member 23A is fixed to the outer circumference on the back side of the main valve 23 by means of seizing or other means. The main valve 23 opens by moving away from the annular valve seat 21D in response to the pressure on the oil passage 21B side (annular oil chamber D side) of the valve member 21. As a result, the oil passage 21B (annular oil chamber D side) of the valve member 21 is connected to the oil chamber 19C (reservoir chamber A side) via the main valve 23, and the amount (flow rate) of pressurized oil flowing in the direction of arrow Y is variably adjusted according to the opening degree of the main valve 23.

[0038] The pilot pin 24 is formed in a stepped cylindrical shape, with an annular large-diameter portion 24A provided in the axial middle section. The pilot pin 24 has a central hole 24B that extends axially on its inner circumference. A small-diameter hole (orifice 24C) is formed at one end of the central hole 24B (the end on the connecting pipe body 20 side). One end of the pilot pin 24 (the left end in Figures 1 and 2) is press-fitted into the central hole 21A of the valve member 21, and the main valve 23 is sandwiched between the large-diameter portion 24A and the valve member 21.

[0039] The other end of the pilot pin 24 (the right end in Figures 1 and 2) is fitted into the central hole 26C of the pilot body 26. In this state, an axially extending oil passage 25 is formed between the central hole 26C of the pilot body 26 and the other end of the pilot pin 24. This oil passage 25 communicates with the back pressure chamber 27 formed between the main valve 23 and the pilot body 26. In other words, multiple axially extending oil passages 25 are provided circumferentially on the side surface of the other end of the pilot pin 24, and the other circumferential positions are press-fitted into the central hole 26C of the pilot body 26.

[0040] The pilot body 26 is formed as a substantially bottomed cylindrical body and has a cylindrical portion 26A with a stepped hole formed on the inside and a bottom portion 26B that closes the cylindrical portion 26A. The bottom portion 26B of the pilot body 26 is provided with a central hole 26C into which the other end of the pilot pin 24 is fitted. A protruding cylindrical portion 26D is integrally provided on one end of the bottom portion 26B of the pilot body 26 (the left end in Figures 1 and 2), located on the outer diameter side and protruding towards the valve member 21 along its entire circumference. The elastic sealing member 23A of the main valve 23 is liquid-tightly fitted to the inner circumferential surface of the protruding cylindrical portion 26D, thereby forming a back pressure chamber 27 between the main valve 23 and the pilot body 26. The back pressure chamber 27 generates pressure (internal pressure, pilot pressure) that presses the main valve 23 in the closing direction, that is, in the direction that causes the main valve 23 to seat on the annular valve seat 21D of the valve member 21.

[0041] At the other end of the bottom portion 26B of the pilot body 26 (the right end in Figures 1 and 2), a valve seat portion 26E is provided so as to surround the central hole 26C, on which the pilot valve body 32 sits and unseats. Inside the cylindrical portion 26A of the pilot body 26, a return spring 28 is provided to bias the pilot valve body 32 away from the valve seat portion 26E of the pilot body 26. A disc valve 29 constitutes a fail-safe valve when the solenoid 33 is not energized (when the pilot valve body 32 is furthest away from the valve seat portion 26E). A retaining plate 30 with an oil passage 30A formed on its central side is also provided.

[0042] At the open end of the cylindrical portion 26A of the pilot body 26, a cap 31 is fitted and fixed with a return spring 28, a disc valve 29, a retaining plate 30, etc., arranged inside the cylindrical portion 26A. The cap 31 has, for example, four notches 31A formed at spaced apart in the circumferential direction. As shown by arrow X in Figure 2, the notches 31A serve as passages that allow the oil liquid that has flowed to the solenoid 33 side through the oil passage 30A of the retaining plate 30 to flow to the oil chamber 19C (reservoir chamber A side).

[0043] The pilot valve body 32, together with the pilot body 26, constitutes a pilot valve (control valve). The pilot valve body 32 is formed in a stepped cylindrical shape. The tip of the pilot valve body 32, that is, the tip that seats away from the valve seat portion 26E of the pilot body 26, is tapered. The operating pin 49 of the solenoid 33 is fitted and fixed inside the pilot valve body 32, and the opening pressure of the pilot valve body 32 is adjusted in accordance with the energization of the solenoid 33. Thus, the pilot valve (pilot body 26 and pilot valve body 32) as a control valve is controlled by the axial movement of the operating pin 49 (i.e., armature 48) of the solenoid 33. A flange portion 32A, which serves as a spring seat, is formed around the entire circumference of the base end of the pilot valve body 32. The flange portion 32A constitutes a fail-safe valve by contacting the inner circumference of the disc valve 29 when the solenoid 33 is de-energized, that is, when the pilot valve body 32 is displaced to the fully open position, which is the furthest distance from the valve seat portion 26E.

[0044] Next, the solenoid 33, which constitutes the damping force adjustment mechanism 17 together with the damping force adjustment valve 18, will be explained with reference to Figures 3 and 4, in addition to Figures 1 and 2. Note that in Figure 3, the right side of Figure 2 is considered the upper side, and the reference numerals are assigned accordingly. That is, the left and right directions in Figures 1 and 2 correspond to the up and down directions in Figures 3 and 4.

[0045] The solenoid 33 is incorporated into the damping force adjustment mechanism 17 as a variable damping force actuator. That is, the solenoid 33 is used in a damping force adjustable shock absorber to adjust the on-off valve operation of the damping force adjustment valve 18. The solenoid 33 comprises a molded coil 34, a housing 36 as a magnetic member (storage member), a yoke 39, an anchor 41 as a fixed core (stator), a cylinder 44 as a connecting member (non-magnetic ring), an armature 48 as a movable core (movable element), an operating pin 49 as a shaft, and a cover member 51.

[0046] The molded coil 34 is formed in a substantially cylindrical shape by winding a coil 34A around a coil bobbin 34B and then integrally covering (molding) them with a resin member 34C such as a thermosetting resin. A cable outlet 34E is provided on a part of the circumferential direction of the molded coil 34, protruding outward in the axial or radial direction, and an electric wire cable (not shown) is connected to this cable outlet 34E. The coil 34A of the molded coil 34 is wound in a ring around the coil bobbin 34B, and when power is supplied (energized) from an external cable, it becomes an electromagnet and generates a magnetic field (magnetic force).

[0047] A seal groove 34D is formed around the entire circumference of the resin member 34C of the molded coil 34 on the side (the end face on one axial side) facing the yoke 39 (annular portion 39B). A seal member (for example, an O-ring 35) is fitted inside the seal groove 34D. The O-ring 35 provides a liquid-tight seal between the molded coil 34 and the yoke 39 (annular portion 39B). This prevents rainwater and dust containing mud from entering the cylindrical projection 39C side of the yoke 39 through the gap between the yoke 39 and the molded coil 34.

[0048] The coil used in this embodiment is not limited to a molded coil 34 consisting of a coil 34A, a coil bobbin 34B, and a resin member 34C; other coils may also be used. For example, the coil may be wound around a coil bobbin made of an electrically insulating material, and the outer circumference of the coil may be covered by an overmolding (not shown) in which a resin material is molded on top of (the outer circumference side).

[0049] The housing 36 constitutes a magnetic member (storage member) positioned on the inner circumference side of the molded coil 34 (i.e., the inner circumference of the coil 34A). The housing 36 is formed as a covered cylindrical body from a magnetic material (magnetic body) such as low carbon steel or carbon steel for machine structures (S10C). The housing 36 is composed of a storage cylinder portion 36A that extends in the direction of the winding axis of the molded coil 34 (coil 34A) and has an open end (left side in Figure 2, lower side in Figure 3), a stepped lid portion 36B that closes the other end (right side in Figure 2, upper side in Figure 3) of the storage cylinder portion 36A, and a small-diameter cylinder portion 36C for joining that is formed on the open side (one side) of the storage cylinder portion 36A so as to reduce its outer diameter.

[0050] The inner circumference of the cylinder 44 is joined to the outer circumference of the small-diameter cylindrical portion 36C of the housing 36 by brazing. The inner diameter of the housing cylindrical portion 36A of the housing 36 is formed to be slightly larger than the outer diameter of the armature 48, and the armature 48 is housed within the housing cylindrical portion 36A so as to be movable in the axial direction. That is, the housing 36 is open at one end in the axial direction, and the armature 48 is housed there. The housing cylindrical portion 36A of the housing 36 has, in order from the inner circumference of the open end (from the inner diameter side to the outer diameter side), a first end portion 36D, a second end portion 36E, and a third end portion 36F.

[0051] The first end 36D faces the anchor 41, more specifically, the outer circumferential protrusion 41C (reduced diameter portion 41C1) of the anchor 41. The first end 36D constitutes a magnetic flux transfer portion for transferring magnetic flux with the armature 48. The second end 36E abuts against the other axial end 44A of the cylinder 44. By abutting against the other end 44A of the cylinder 44, the second end 36E constitutes a position fixing portion for aligning (positioning) the housing 36. The third end 36F faces the other end 44A of the cylinder 44 with a gap between them, and this gap serves as a brazing material storage portion where a brazing material (copper ring) that serves as a sealing material is stored. The housing 36 and the cylinder 44 form a pressure vessel by press-fitting the housing 36 (small diameter cylindrical portion 36C) into the inside of the cylinder 44 and brazing them together.

[0052] On the other hand, the lid portion 36B of the housing 36 is integrally formed with the storage cylinder portion 36A as a covered cylindrical body that closes the storage cylinder portion 36A from the other axial side. The outer diameter of the lid portion 36B is smaller than the outer diameter of the storage cylinder portion 36A and has a stepped shape, and the fitting cylindrical portion 51A of the cover member 51 is fitted and provided on the outer circumference of the lid portion 36B. In addition, the housing 36 has a bottomed stepped hole 37 located inside the lid portion 36B. The stepped hole 37 consists of a bush mounting hole portion 37A and a small-diameter hole portion 37B which is located further back than the bush mounting hole portion 37A and has a smaller diameter. A first bush 38 is provided inside the bush mounting hole portion 37A as a bearing for slidably supporting the operating pin 49.

[0053] Furthermore, the lid portion 36B of the housing 36 is positioned opposite the lid plate 51B of the cover member 51 with an axial gap between them. This axial gap prevents axial force from being directly applied to the housing 36 from the lid plate 51B side of the cover member 51 via the lid portion 36B. It should be noted that the lid portion 36B of the housing 36 does not necessarily have to be formed integrally with the storage cylinder portion 36A from the same material (magnetic material). In this case, the lid portion 36B can be formed from a material other than a magnetic material, such as a rigid metal material, ceramic material, or fiber-reinforced resin material. The joint between the storage cylinder portion 36A and the lid portion 36B of the housing 36 is positioned to allow for the transfer of magnetic flux.

[0054] The yoke 39 is provided on one side in the direction of movement of the armature 48. The yoke 39 is a magnetic member that, together with the housing 36, forms a magnetic circuit (magnetic path) across the inner and outer circumferences of the molded coil 34 (coil 34A). The yoke 39 is formed using a magnetic material (magnetic body) similar to the housing 36, and includes an annular portion 39B that extends radially on one axial side (one side in the winding axis direction) of the molded coil 34 (coil 34A), with its inner circumference having a stepped fixing hole 39A, and a cylindrical projection 39C that protrudes cylindrically from the inner circumference of the annular portion 39B toward the other axial side (coil 34A side) along the axial direction of the fixing hole 39A. The cylindrical projection 39C constitutes a projection (cylindrical portion) for joining with the cylinder 44, and the cylinder 44 is inserted into the inner diameter side of the cylindrical projection 39C.

[0055] In other words, the yoke 39 has a fixing hole 39A, and the inner circumferential surface of the fixing hole 39A faces a part of the side surface 41D of the anchor 41. Furthermore, an inward-facing flange portion 39D is provided inside the fixing hole 39A, projecting inward along its entire circumference. The side surface of the inward-facing flange portion 39D (the side surface on the coil 34A side) is in contact with one axial end surface of the cylinder 44. Also, the outer circumference of one axial side of the cylinder 44 is fitted into the inner circumference of the yoke 39, that is, the inner surface of the fixing hole 39A (in other words, the inner circumferential surface of the cylindrical projection 39C).

[0056] Furthermore, the yoke 39 is formed as a single unit including a cylindrical one-side section 39G extending from the outer circumference of the annular section 39B toward one axial side (towards the damping force adjustment valve 18), an other-side section 39H extending from the outer circumference of the annular section 39B toward the other axial side (towards the cover member 51) and formed to surround the molded coil 34 from the radially outer side, and a crimping section 39J provided at the tip of the other-side section 39H to hold the flange 51C of the cover member 51 in a non-detachable state. The other-side section 39H of the yoke 39 is provided with a notch 39K to expose the cable outlet 34E of the molded coil 34 to the outside of the other-side section 39H.

[0057] Between the one cylindrical portion 39G and the other cylindrical portion 39H of the yoke 39, there are engagement recesses 39L with a semicircular cross-section that open to the outer circumferential surface of the yoke 39 (either all around or at multiple locations spaced apart in the circumferential direction). A lock nut 53, which is screwed onto the valve case 19 of the damping force adjustment valve 18, engages with the engagement recesses 39L via a retaining ring 54 (see Figure 2). Furthermore, a seal groove 39M is provided all around the outer circumferential surface of the one cylindrical portion 39G. An O-ring 40 (see Figure 2) is fitted into the seal groove 39M as a sealing member. The O-ring 40 provides a liquid-tight seal between the yoke 39 (one cylindrical portion 39G) and the valve case 19 of the damping force adjustment valve 18.

[0058] The anchor 41 is provided on one side of the armature 48 in the direction of movement. The anchor 41 is positioned opposite the armature 48 in the axial direction. The anchor 41 is a fixed iron core (stator) fixed into the fixing hole 39A of the yoke 39 by means of press-fitting or other means. The anchor 41, like the housing 36 and the yoke 39, is formed from a magnetic material (magnetic body) such as low carbon steel or machine structural carbon steel (S10C) to fill the fixing hole 39A of the yoke 39 from the inside. The anchor 41 is formed as a short cylindrical annular body with a through hole 41A extending axially at its center. One axial side of the anchor 41 (the side facing the cap 31 of the damping force adjustment valve 18 in the axial direction as shown in Figure 2) is formed to be a flat surface, similar to one side of the annular portion 39B of the yoke 39.

[0059] On the other axial side of the anchor 41 (the side opposite the armature 48 in the axial direction), a circular recess 41B is provided, coaxial with the housing cylinder 36A of the housing 36. The recess 41B is formed as a circular groove slightly larger in diameter than the armature 48, so that the armature 48 can be inserted into and out of it by magnetic force. For this purpose, a cylindrical outer circumferential protrusion 41C is provided on the other side of the anchor 41. The outer circumferential surface on the opening side of the outer circumferential protrusion 41C is formed as a conical surface so that the magnetic properties between the anchor 41 and the armature 48 are linear.

[0060] In other words, the outer peripheral projection 41C, also called the corner portion, protrudes cylindrically from the outer peripheral side of the anchor 41 toward the other axial direction. The outer peripheral surface of the outer peripheral projection 41C (the outer peripheral surface on the opening side) is a conical surface that is tapered inclined so that the outer diameter gradually decreases toward the other axial direction (the opening side). In other words, the outer peripheral projection 41C of the anchor 41 is provided at a position facing the opening of the housing 36 (storage cylinder portion 36A) (more specifically, the first end portion 36D), and has a reduced diameter portion 41C1 whose outer diameter decreases as it approaches the opening of the storage cylinder portion 36A.

[0061] Furthermore, a side portion 41D is formed on the outer circumference of the anchor 41, extending away from the opening of the housing cylinder portion 36A of the housing 36 along the outer circumference of the outer peripheral protrusion 41C. The end of this side portion 41D that is away from the opening is an annular flange portion 41E that protrudes radially outward. The annular flange portion 41E is positioned at a location significantly separated in one axial direction from the opening end of the housing cylinder portion 36A of the housing 36 (i.e., the end opposite to the recessed portion 41B).

[0062] The annular flange portion 41E is fixed, for example, by means of press-fitting into the fixing hole 39A of the yoke 39. The annular flange portion 41E serves as the fixing portion of the anchor 41 (side portion 41D) to the fixing hole 39A of the yoke 39, and is also the portion where the flange portion 41E and the fixing hole 39A face each other in the radial direction. The side portion 41D of the anchor 41 (excluding the annular flange portion 41E) faces the inner circumferential surface of the cylinder 44 and the inner surface of the inward-facing flange portion 39D of the yoke 39 with a gap (radial gap) between them.

[0063] The anchor 41 has an outer peripheral projection 41C and a side portion 41D that are integrally formed from a magnetic material. The anchor 41 is positioned opposite the opening of the housing cylinder portion 36A of the housing 36. The outer peripheral projection 41C protrudes toward the opening of the housing cylinder portion 36A of the housing 36. The side portion 41D extends from the outer circumference of the outer peripheral projection 41C in a direction away from the opening of the housing cylinder portion 36A of the housing 36. The side portion 41D has a gap with respect to the inner circumferential surface of the cylinder 44 and the inner surface of the inward-facing flange portion 39D of the yoke 39.

[0064] As shown in Figure 3, a second bush 43, which serves as a bearing for slidably supporting the operating pin 49, is fitted into a stepped through hole 41A formed on the central (inner circumference) side of the anchor 41. On the other hand, as shown in Figure 2, the pilot body 26, return spring 28, disc valve 29, retaining plate 30, and cap 31 of the damping force adjustment valve 18 are inserted and provided on the inner circumference side of one side cylindrical portion 39G of the yoke 39. In addition, the valve case 19 of the damping force adjustment valve 18 is fitted (externally fitted) to the outer circumference side of one side cylindrical portion 39G.

[0065] The cylinder 44 is located between the yoke 39 and the anchor 41 in the radial direction. Furthermore, the cylinder 44 is located between the yoke 39 and the housing 36 in both the axial and radial directions. That is, the cylinder 44 is a non-magnetic connecting member (joining member) located between the small-diameter cylindrical portion 36C of the housing 36 and the cylindrical projection 39C of the yoke 39, and provided on the inner circumference side of the molded coil 34 (coil 34A). The cylinder 44 is made of a non-magnetic material. More specifically, the cylinder 44 is formed as a cylindrical body (simple cylindrical body) from a non-magnetic material such as austenitic stainless steel.

[0066] The cylinder 44 is joined to the inner circumference of the yoke 39 (fixing hole 39A, cylindrical projection 39C) at one end (yoke 39 side) in the winding axis direction of the molded coil 34 (coil 34A). In this way, the cylinder 44 is fixed to the yoke 39, which has one side in the axial direction as a stator. The other end (housing 36 side) of the cylinder 44 in the winding axis direction is joined to the outer circumference of the housing 36 (small diameter cylindrical portion 36C). That is, the cylinder 44 is fitted (press-fitted) to the outside (outer circumference side) of the small diameter cylindrical portion 36C of the housing 36, and the two are joined by brazing.

[0067] In this embodiment, the housing 36 and the cylinder 44, and the cylinder 44 and the yoke 39 are joined via brazing material. For example, pure copper brazing material can be used. That is, brazing can be performed using a brazing material (copper ring) made of pure copper brazing material, for example, by a brazing treatment at 1000°C or higher. Note that the brazing material may be something other than pure copper brazing material. For example, brass brazing material, nickel brazing material, gold brazing material, palladium brazing material, etc. may also be used. In any case, the cylinder 44 is joined to the small diameter cylindrical portion 36C of the housing 36 and the cylindrical projection portion 39C of the yoke 39 by brazing.

[0068] The armature 48 is positioned between the housing cylinder portion 36A of the housing 36 and the recessed portion 41B of the anchor 41. The armature 48 is a movable iron core (movable element) made of a magnetic material that is provided to move in the direction of the winding axis of the coil 34A. That is, the armature 48 is provided on the inner circumference side of the coil 34A so as to be movable in the axial direction. The armature 48 is positioned on the inner circumference side of the housing cylinder portion 36A of the housing 36, the recessed portion 41B of the anchor 41, the cylindrical projection 39C of the yoke 39, and the cylinder 44, and is movable in the axial direction between the housing cylinder portion 36A of the housing 36 and the recessed portion 41B of the anchor 41. That is, the armature 48 is positioned on the inner circumference side of the housing cylinder portion 36A of the housing 36 and the recessed portion 41B of the anchor 41, and is movable in the axial direction via the first and second bushings 38, 43 and the operating pin 49 due to the magnetic force generated in the coil 34A.

[0069] The armature 48 is fixed (integrated) to an actuation pin 49 that extends through its center and moves together with the actuation pin 49. The actuation pin 49 is axially slidable between the lid 36B of the housing 36 and the anchor 41 via first and second bushings 38 and 43. Here, the armature 48 is formed in a substantially cylindrical shape using an iron-based magnetic material, similar to the housing 36, yoke 39, and anchor 41. The magnetic force generated in the coil 34A generates a thrust (attractive force) in the direction that attracts the armature 48 toward the recess 41B of the anchor 41.

[0070] The actuation pin 49 is the shaft portion that transmits the thrust of the armature 48 to the pilot valve body 32 of the damping force adjustment valve 18 (control valve), and is formed of a hollow rod. The actuation pin 49 is displaced integrally with the armature 48. That is, the armature 48 is integrally fixed to the axial middle portion of the actuation pin 49 by means of press-fitting or other means, thereby sub-assemblying the armature 48 and the actuation pin 49. Both axial sides of the actuation pin 49 are slidably supported by the cover portion 36B on the housing 36 side and the yoke 39 (anchor 41) via first and second bushings 38 and 43.

[0071] One end of the actuation pin 49 (the left end in Figure 2, the lower end in Figure 3) protrudes axially from the anchor 41 (yoke 39), and the pilot valve body 32 of the damping force adjustment valve 18 is fixed to this protruding end. Therefore, the pilot valve body 32 moves integrally in the axial direction together with the armature 48 and the actuation pin 49. In other words, the opening pressure of the pilot valve body 32 is a pressure value corresponding to the thrust of the armature 48 based on the energization of the coil 34A. The armature 48 moves axially due to the magnetic force from the coil 34A, thereby opening and closing the pilot valve of the buffer 1 (i.e., the pilot valve body 32 relative to the pilot body 26).

[0072] The cover member 51 is a magnetic cover that covers the molded coil 34 from the outside together with the other cylindrical portion 39H of the yoke 39. This cover member 51 is made of a magnetic material (magnetic body) as a lid that covers the molded coil 34 from the other axial side, and together with the other cylindrical portion 39H of the yoke 39, it forms a magnetic circuit (magnetic path) on the outside of the molded coil 34 (coil 34A). The cover member 51 is formed as a covered cylindrical shape and is generally composed of a cylindrical fitting cylinder portion 51A and a disc-shaped lid plate 51B that closes the other end of the fitting cylinder portion 51A (the right end in Figure 2, the upper end in Figure 3).

[0073] Here, the fitting cylindrical portion 51A of the cover member 51 is inserted onto the outer circumference of the lid portion 36B of the housing 36, and in this state, the lid portion 36B of the housing 36 is housed inside. On the other hand, the lid plate 51B of the cover member 51 has an annular flange portion 51C that extends radially outward from the fitting cylindrical portion 51A on its outer circumference, and the outer edge of the flange portion 51C is fixed to a crimping portion 39J provided on the other cylindrical portion 39H of the yoke 39. As a result, the other cylindrical portion 39H of the yoke 39 and the lid plate 51B of the cover member 51 are pre-assembled (sub-assembled) with the molded coil 34 built inside, as shown in Figure 3.

[0074] In this configuration, with the molded coil 34 housed inside the other cylindrical portion 39H of the yoke 39 and the lid plate 51B of the cover member 51, the lid portion 36B of the housing 36 is fitted into the fitting cylindrical portion 51A of the cover member 51. This allows for the transfer of magnetic flux between the fitting cylindrical portion 51A of the cover member 51, the lid plate 51B, and the yoke 39. Furthermore, a seal groove 51D is formed around the entire circumference of the fitting cylindrical portion 51A of the cover member 51, on the outer circumference where the resin member 34C of the molded coil 34 is fitted. A sealing member (for example, an O-ring 52) is installed in this seal groove 51D. The O-ring 52 provides a liquid-tight seal between the molded coil 34 and the cover member 51 (fitting cylindrical portion 51A). This prevents rainwater and dust containing mud from entering the space between the cover member 51 and the molded coil 34, and further into the space between the housing 36 and the molded coil 34, and even between the housing 36 and the cover member 51.

[0075] As shown in Figure 3, the yoke 39 and the cover member 51 have a molded coil 34 built inside, and as shown in Figure 2, they are fastened to the valve case 19 of the damping force adjustment valve 18 using a lock nut 53 and a retaining ring 54 as fastening members. In this case, the retaining ring 54 is attached to the engagement recess 39L of the yoke 39 before the lock nut 53. This retaining ring 54 partially protrudes radially outward from the engagement recess 39L of the yoke 39 and transmits the fastening force from the lock nut 53 to the one side cylindrical portion 39G of the yoke 39.

[0076] The lock nut 53 is formed as a stepped cylindrical body and has a female threaded portion 53A located on one axial side and on its inner circumference that screws into the male threaded portion 19B of the valve case 19, and an engaging cylindrical portion 53B that is bent radially inward so that its inner diameter is smaller than the outer diameter of the retaining ring 54 and engages with the retaining ring 54 from the outside. The lock nut 53 is a fastening member that integrally connects the damping force adjustment valve 18 and the solenoid 33 by screwing the female threaded portion 53A and the male threaded portion 19B of the valve case 19 together with the inner surface of the engaging cylindrical portion 53B in contact with the retaining ring 54 which is mounted in the engaging recess 39L of the yoke 39.

[0077] Incidentally, the solenoid described in Patent Document 1 above has a notch formed in the circumferential direction at a position where the movable element (movable core) and the stator (fixed core) face each other. In this case, the axial attractive force between the movable element and the stator (thrust of the movable element) decreases, and the movable element may become difficult to move, especially at low currents. In addition, the notch in the circumferential direction may cause a large change in the thrust characteristics. For this reason, in the case of the conventional technology, in order to secure thrust while suppressing vibration, it is necessary to change the solenoid structure, such as extending the shaft length or increasing the outer diameter, which may increase additional costs.

[0078] In any case, it is undesirable for the thrust of the movable element to decrease and for the thrust characteristics to change as a result of forming a notch in the movable element. Furthermore, it is undesirable for the vibration suppression effect to be insufficient due to insufficient radial attraction force (radial bias of attraction force) on the movable element. Therefore, the embodiment employs the following configuration. That is, the armature 48, which is the movable element (movable iron core), has a large diameter section 48A and a small diameter section 48B, and the small diameter section 48B is positioned on the anchor 41 side, which is the fixed iron core (stator). This ensures both radial attraction force (vibration suppression force) and axial attraction force (thrust) between the anchor 41 and the armature 48. These points will be explained below.

[0079] First, as shown in Figure 1, the shock absorber 1 comprises an inner cylinder 4 and an outer cylinder 2 as cylinders, a piston 5, a piston rod 8, an annular oil chamber D that serves as a flow path (more specifically, the flow path between the annular oil chamber D and the reservoir chamber A), and a damping force adjustment valve 18 driven by a solenoid 33. Also, as shown in Figure 2, the damping force adjustment mechanism 17 comprises a coil 34A, an armature 48 as a movable element, an anchor 41 as a stator, and a pilot valve (pilot body 26 and pilot valve body 32) and consequently the damping force adjustment valve 18 as a control valve. Furthermore, as shown in Figure 3, the solenoid 33 comprises a coil 34A, an armature 48 as a movable core, an anchor 41 as a fixed core, and an operating pin 49 as a shaft. The solenoid also comprises a housing 36 as a magnetic member.

[0080] The coil 34A generates a magnetic field when energized. The armature 48 is located on the inner circumference of the coil 34A, at least in part, and is axially movable. In other words, the armature 48 is located on the inner circumference of the coil 34A and is axially movable. The anchor 41 is axially opposite to the armature 48. The actuation pin 49 displaces integrally with the armature 48. The housing 36 is located radially between the coil 34A and the armature 48.

[0081] As shown in Figures 3 and 4, the armature 48 has a large-diameter portion 48A and a small-diameter portion 48B. In this case, the small-diameter portion 48B is located on the anchor 41 side. That is, the radial gap between the armature 48 and the housing 36 is larger on the anchor 41 side compared to other locations. The large-diameter portion 48A has the same diameter (outer diameter D) at all positions in the circumferential direction, i.e., it has a continuous circular periphery in the circumferential direction. The small-diameter portion 48B has the same diameter (outer diameter d) at all positions in the circumferential direction, i.e., it has a continuous circular periphery in the circumferential direction. The large-diameter portion 48A and the small-diameter portion 48B have a circular cross-sectional shape at all positions in the axial direction. The large-diameter portion 48A and the small-diameter portion 48B, which have different outer diameters, are connected by a stepped surface 48C.

[0082] The large-diameter portion 48A, which faces the bottom (lid portion 36B) of the housing 36, is larger in diameter than the small-diameter portion 48B, which faces the anchor 41. That is, the large-diameter portion 48A has a larger outer diameter than the small-diameter portion 48B. If the outer diameter of the large-diameter portion 48A is D and the outer diameter of the small-diameter portion 48B is d, then for example, D can be set to 1.01d to 1.02d. In this case, for example, the outer diameter d of the small-diameter portion 48B maintains the same dimension as a configuration in which the outer diameter of the movable core (armature) is the same across the entire axial direction (for example, the current product). On the other hand, the outer diameter D of the large-diameter portion 48A is enlarged by about 1 to 2% of the outer diameter d of the small-diameter portion 48B.

[0083] The large-diameter section 48A has a magnetic force that is strongest at the point where the gap between it and the housing 36 on the outer diameter side of the armature 48 is smallest, depending on the manufacturing tolerance of the large-diameter section 48A. Therefore, the large-diameter section 48A can create a bias in the circumferential direction of the radial attractive force, and can absorb vibrations of the armature 48. On the other hand, the small-diameter section 48B can ensure axial attractive force (thrust of the armature 48) by having the same diameter (circular cross-section) at all positions in the circumferential direction. The shorter the axial length L1 of the large-diameter section 48A, for example, the lower the vibration suppression effect. If the axial length L1 of the large-diameter section 48A and the axial length L2 of the small-diameter section 48B are, for example, the same, the vibration suppression effect is high. Conversely, if the axial length L1 of the large-diameter section 48A is longer than the axial length L2 of the small-diameter section 48B, the impact on the thrust characteristics will be greater (for example, the change in thrust characteristics will be larger compared to the current product).

[0084] In this embodiment, the axial length L1 of the large-diameter section 48A is the same as, or shorter than, the axial length L2 of the small-diameter section 48B. This suppresses vibration based on the radial attractive force bias caused by the large-diameter section 48A, while suppressing a decrease in thrust and a change in characteristics. The actuation pin 49, which displaces integrally with the armature 48, is provided by extending axially from the inner circumference of the armature 48 and anchor 41. The actuation pin 49 is equipped with bushings 38 and 43 as bearings at both axial ends.

[0085] On the other hand, a housing 36, which acts as a magnetic element, is provided on the outer circumference of the armature 48. Furthermore, the gap between the large-diameter portion 48A of the armature 48 and the housing 36 is made larger than the gap between the bushes 38, 43 and the operating pin 49. That is, the difference between the outer diameter of the large-diameter portion 48A and the inner diameter of the housing 36 is greater than the difference between the outer diameter of the operating pin 49 and the inner diameters of the bushes 38, 43. Therefore, contact between the large-diameter portion 48A and the housing 36 can be suppressed.

[0086] Furthermore, the gap between the armature 48 (large diameter portion 48A) and the housing 36 is smaller than the gap (radial gap) between the armature 48 (small diameter portion 48B) and the anchor 41 (outer peripheral protrusion 41C of the recessed portion 41B). In other words, the difference between the outer diameter of the large diameter portion 48A and the inner diameter of the housing 36 is smaller than the difference between the outer diameter of the small diameter portion 48B and the inner diameter of the outer peripheral protrusion 41C. Therefore, contact between the small diameter portion 48B and the anchor 41 (recessed portion 41B) can be suppressed.

[0087] In other words, the solenoid 33 of this embodiment drives the armature 48, which is a movable core consisting of at least a first magnetoresistance section, in the axial direction by the magnetic action when the coil 34A is energized. The solenoid 33 includes an operating pin 49 as a shaft portion mounted on the armature 48, and bushings 38 and 43 as bearings that support both ends of the armature 48. Furthermore, the solenoid 33 includes a second magnetoresistance section that exerts an action to move at least the armature 48 radially by magnetic action. This second magnetoresistance section consists of a notch that cuts out one side of the armature 48 in the axial direction, extending in the circumferential direction. This notch corresponds to a small diameter portion 48B formed on the anchor 41 side of the armature 48 by cutting out the entire circumference in the circumferential direction.

[0088] The solenoid 33, damping force adjustment mechanism 17, and shock absorber 1 according to this embodiment have the configuration described above, and their operation will now be explained.

[0089] First, when the shock absorber 1 is installed in a vehicle such as an automobile, for example, the upper end (protruding end) of the piston rod 8 is attached to the vehicle body, and the mounting eye 3A on the bottom cap 3 is attached to the wheel. In addition, the solenoid 33 of the damping force adjustment mechanism 17 is connected to a control device (controller) installed on the vehicle body via electrical wiring cables (neither of which are shown).

[0090] When the vehicle is in motion, if vibrations occur in the upward or downward direction due to unevenness in the road surface, the piston rod 8 is displaced so as to extend or contract from the outer cylinder 2, and damping force can be generated by the damping force adjustment mechanism 17, etc., thereby mitigating the vibrations of the vehicle. At this time, the damping force generated by the shock absorber 1 can be variably adjusted by controlling the current value to the coil 34A of the solenoid 33 with the controller and adjusting the opening pressure of the pilot valve body 32.

[0091] For example, during the extension stroke of the piston rod 8, the movement of the piston 5 inside the inner cylinder 4 closes the compression-side check valve 7 of the piston 5. Before the disc valve 6 of the piston 5 opens, the oil in the rod-side oil chamber B is pressurized and flows into the oil passage 20B of the connecting pipe 20 of the damping force adjustment valve 18 through the oil hole 4A of the inner cylinder 4, the annular oil chamber D, and the connection port 12C of the intermediate cylinder 12. At this time, the amount of oil that has moved due to the piston 5 flows from the reservoir chamber A into the bottom-side oil chamber C by opening the extension-side check valve 16 of the bottom valve 13. When the pressure in the rod-side oil chamber B reaches the opening pressure of the disc valve 6, the disc valve 6 opens and relieves the pressure in the rod-side oil chamber B to the bottom-side oil chamber C.

[0092] In the damping force adjustment mechanism 17, the oil that flows into the oil passage 20B of the connecting pipe 20 passes through the central hole 21A of the valve member 21, the central hole 24B of the pilot pin 24, and the central hole 26C of the pilot body 26, as shown by arrow X in Figure 2, before the main valve 23 opens (in the low piston speed range), pushing open the pilot valve body 32 and flowing into the inside of the pilot body 26. The oil that has flowed into the inside of the pilot body 26 then flows through the space between the flange portion 32A of the pilot valve body 32 and the disc valve 29, the oil passage 30A of the retaining plate 30, the notch 31A of the cap 31, and the oil chamber 19C of the valve case 19 to the reservoir chamber A. As the piston speed increases, when the pressure in the oil passage 20B of the connecting pipe 20, i.e., the pressure in the rod-side oil chamber B, reaches the opening pressure of the main valve 23, the oil that has flowed into the oil passage 20B of the connecting pipe 20 passes through the oil passage 21B of the valve member 21, as shown by arrow Y in Figure 2, pushes open the main valve 23, and flows through the oil chamber 19C of the valve case 19 to the reservoir chamber A.

[0093] On the other hand, during the compression stroke of the piston rod 8, the movement of the piston 5 inside the inner cylinder 4 opens the compression-side check valve 7 of the piston 5, and the extension-side check valve 16 of the bottom valve 13 closes. Before the bottom valve 13 (disc valve 15) opens, the oil from the bottom-side oil chamber C flows into the rod-side oil chamber B. At the same time, the amount of oil equivalent to the amount the piston rod 8 has entered inside the inner cylinder 4 flows from the rod-side oil chamber B to the reservoir chamber A via the damping force adjustment valve 18, following the same path as during the extension stroke. When the pressure inside the bottom-side oil chamber C reaches the opening pressure of the bottom valve 13 (disc valve 15), the bottom valve 13 (disc valve 15) opens, relieving the pressure in the bottom-side oil chamber C to the reservoir chamber A.

[0094] As a result, during the extension and compression strokes of the piston rod 8, before the main valve 23 of the damping force adjustment valve 18 opens, a damping force is generated by the orifice 24C of the pilot pin 24 and the opening pressure of the pilot valve body 32. After the main valve 23 opens, a damping force is generated according to the opening degree of the main valve 23. In this case, by adjusting the opening pressure of the pilot valve body 32 by energizing the coil 34A of the solenoid 33, the damping force can be directly controlled regardless of the piston speed.

[0095] Specifically, reducing the current supplied to coil 34A and decreasing the thrust of armature 48 lowers the opening pressure of pilot valve body 32, generating a soft damping force. On the other hand, increasing the current supplied to coil 34A and increasing the thrust of armature 48 increases the opening pressure of pilot valve body 32, generating a hard damping force. At this time, the opening pressure of pilot valve body 32 changes the internal pressure of the back pressure chamber 27, which is connected to it via the oil passage 25 upstream of it. As a result, by controlling the opening pressure of pilot valve body 32, the opening pressure of the main valve 23 can be adjusted simultaneously, widening the adjustment range of the damping force characteristics.

[0096] Furthermore, if the thrust of the armature 48 is lost due to a break in the coil 34A or the like, the pilot valve body 32 is retracted by the return spring 28 (displaced away from the valve seat 26E), and the flange portion 32A of the pilot valve body 32 comes into contact with the disc valve 29. In this state, damping force can be generated by the opening pressure of the disc valve 29, and the necessary damping force can be obtained even in the event of a malfunction such as a broken coil.

[0097] In this embodiment, the armature 48 has a large-diameter portion 48A and a small-diameter portion 48B, and the small-diameter portion 48B is provided on the anchor 41 side. Therefore, the small-diameter portion 48B on the anchor 41 side of the armature 48 (i.e., the side facing the anchor 41 in the axial direction) has the same diameter at all positions in the circumferential direction (a circular periphery that is uniformly continuous in the circumferential direction), thereby ensuring axial attractive force. This ensures the thrust of the armature 48. On the other hand, the large-diameter portion 48A on the opposite side of the armature 48 (opposite the anchor 41) has a magnetic force that is greatest at the point where the gap between it and the housing 36 is smallest, depending on the manufacturing tolerance of the large-diameter portion 48A. Therefore, a circumferential bias can be generated in the radial attractive force, and vibrations of the armature 48 can be absorbed. This makes it possible to achieve both ensuring the thrust of the armature 48 and suppressing vibrations. In this case, by making the outer diameter of the small-diameter section 48B the same as, for example, the outer diameter of the current product (a configuration in which the outer diameter of the armature is the same throughout the entire axial direction), the same thrust as the current product can be secured by enlarging the diameter of the large-diameter section 48A without changing the shaft length (L1+L2) of the armature 48. Therefore, it is possible to secure thrust while suppressing vibration without requiring major structural changes from the current product. Moreover, since the small-diameter section 48B (and the large-diameter section 48A) can be formed by turning, for example, on a lathe, additional costs can be reduced.

[0098] According to this embodiment, the actuation pin 49 is provided extending axially from the inner circumference of the armature 48 and anchor 41. This allows for the provision of a long actuation pin 49 on the inner circumference of the armature 48 and anchor 41, while also ensuring sufficient thrust for the actuation pin 49 and suppressing vibration.

[0099] According to this embodiment, the actuation pin 49 is equipped with bushings 38 and 43 that act as bearings at both axial ends. Therefore, the bushings 38 and 43 can smoothly and stably support the actuation pin 49, which is displaced integrally with the armature 48, together with the armature 48.

[0100] According to this embodiment, the second magnetoresistive portion that exerts the effect of moving the armature 48 radially consists of a small-diameter portion 48B formed by cutting out one side of the armature 48 in the axial direction along the circumferential direction. Therefore, the small-diameter portion 48B, which is cut out along the entire circumference of the armature 48, can generate a force that moves the armature 48 radially in the uncut large-diameter portion 48A. This ensures thrust for the armature 48 and suppresses vibration.

[0101] According to this embodiment, the gap between the large-diameter portion 48A of the armature 48 and the housing 36 is larger than the gap between the bushings 38, 43 and the operating pin 49. Therefore, contact between the large-diameter portion 48A of the armature 48 and the housing 36 can be suppressed.

[0102] According to the embodiment, the axial length L1 of the large-diameter section 48A is smaller than the axial length L2 of the small-diameter section 48B. Therefore, by making the outer diameter of the small-diameter section 48B the same as, for example, the outer diameter of the current product (a configuration in which the outer diameter of the armature is the same throughout the entire axial direction), the same thrust as the current product can be secured. Furthermore, by making the axial length L1 of the large-diameter section 48A smaller than the axial length L2 of the small-diameter section 48B, it is possible to suppress vibration based on the radial attractive force (bias of radial attractive force) of the large-diameter section 48A while suppressing a decrease in thrust and a change in characteristics. This improves the robustness of the design.

[0103] According to this embodiment, the damping force adjustment valve 18 of the shock absorber 1 is driven by a solenoid 33. Furthermore, the armature 48 of the solenoid 33 has a large diameter portion 48A and a small diameter portion 48B, and the small diameter portion 48B is provided on the anchor 41 side. This makes it possible to ensure the thrust of the solenoid 33 and suppress vibrations, and to suppress vibrations (abnormal noises) caused by cavitation of the damping force adjustment valve 18 driven by the solenoid 33. As a result, the stability of the shock absorber 1 can be improved.

[0104] According to this embodiment, the armature 48 of the damping force adjustment mechanism 17 has a large-diameter portion 48A and a small-diameter portion 48B, and the small-diameter portion 48B is provided on the anchor 41 side. Therefore, it is possible to achieve both securing the thrust of the armature 48 and suppressing vibration, and to suppress vibration (abnormal noise) due to cavitation of the pilot valve (pilot body 26 and pilot valve body 32) and consequently the damping force adjustment valve 18 controlled by the armature 48.

[0105] According to the embodiment, the radial gap between the armature 48 and the housing 36 is larger on the anchor 41 side compared to other areas. Therefore, on the anchor 41 side (i.e., the side where the armature 48 and anchor 41 face each other in the axial direction), the radial gap is the same width throughout the circumferential direction, thereby ensuring axial attractive force. This ensures the thrust of the armature 48. On the other hand, on the opposite side of the anchor (opposite to the anchor 41), the magnetic force is greater in the area where the radial gap is smallest due to manufacturing tolerances. Therefore, a circumferential bias can be created in the radial attractive force, and vibrations of the armature 48 can be absorbed. This makes it possible to achieve both ensuring the thrust of the armature 48 and suppressing vibrations.

[0106] According to this embodiment, the inner diameter of the housing 36 (storage cylinder portion 36A) is the same, and the outer diameter of the armature 48 is smaller on the anchor 41 side compared to other parts. Therefore, by making the outer diameter of the armature 48 on the anchor 41 side smaller, the radial gap between the armature 48 on the anchor 41 side and the housing 36 can be made larger compared to other parts.

[0107] In this embodiment, the example described was one in which the armature 48 is provided with one large-diameter section 48A and one small-diameter section 48B. However, the invention is not limited to this, and for example, a configuration in which at least one of the large-diameter section and the small-diameter section is provided in multiples is also possible. For example, as shown in the first modified example in Figure 5, the armature 61 may have one large-diameter section 61A and multiple (two) small-diameter sections 61B, 61B. In this case, the armature 61 is arranged in the following order from the anchor 41 side: first small-diameter section 61B, large-diameter section 61A, and second small-diameter section 61B. The outer diameter dimension d of the small-diameter sections 61B, 61B is maintained at the same dimensions as the current product, for example. The outer diameter dimension D of the large-diameter section 61A is enlarged by, for example, about 1-2% of the outer diameter dimension d of the small-diameter section 48B.

[0108] Furthermore, if the first small-diameter portion 61B and the second small-diameter portion 61B have the same outer diameter, and the axial lengths of the large-diameter portion 61A and the small-diameter portions 61B, 61B are the same, then the direction in which the armature 61 is assembled is no longer restricted. That is, in this case, the first small-diameter portion 61B may be on the anchor 41 side, or the second small-diameter portion 61B may be on the anchor 41 side. This eliminates the need for a determination mechanism to distinguish between the large-diameter portion and the small-diameter portion when assembling the armature 61 into the solenoid 33, thereby suppressing incorrect assembly. Although not shown in the figures, multiple small-diameter portions and large-diameter portions (for example, two or more) may be provided.

[0109] In the embodiment, the inner diameter of the housing 36 (storage cylinder portion 36A) is the same, and the outer diameter of the armature 48 is smaller on the anchor 41 side compared to other parts. However, the embodiment is not limited to this, and for example, as shown in the second modified example in Figure 6, the diameter (outer diameter) of the armature 62 is the same, and the inner diameter of the housing 63 as a magnetic member may be larger on the anchor 41 side compared to other parts. That is, in the second modified example in Figure 6, the housing 63 is provided radially between the coil 34A and the armature 62. The radial gap between the armature 62 and the housing 63 (storage cylinder portion 63A) is larger on the anchor 41 side compared to other parts. In this case, the outer diameter of the armature 62 is the same, and the inner diameter of the housing 63 (storage cylinder portion 63A) is larger on the anchor 41 side compared to other parts. In other words, the inner diameter side of the housing 63's storage cylinder portion 63A has a large diameter portion 63B with a larger inner diameter and a small diameter portion 63C with a smaller inner diameter than the large diameter portion 63B, with the large diameter portion 63B being located on the anchor 41 side.

[0110] The outer diameter of the armature 62 is maintained at the same dimensions as the current product, for example. The inner diameter of the large-diameter section 63B of the housing 63 (storage cylinder section 63A) is also maintained at the same dimensions as the current product. On the other hand, the inner diameter dimension d of the small-diameter section 63C of the housing 63 (storage cylinder section 63A) is reduced by about 1-2% compared to the inner diameter dimension D of the large-diameter section 63B, for example. If the inner diameter of the housing (storage cylinder section) is reduced over the entire axial direction (i.e., only the small-diameter section), the change in thrust characteristics compared to the current product will be large. For this reason, in the second modification, the inner diameter is changed by the large-diameter section 63B and the small-diameter section 63C. With this second modification, by increasing the inner diameter of the housing 63 (storage cylinder section 63A) on the anchor 41 side, the radial gap between the armature 62 on the anchor 41 side and the housing 63 can be increased compared to other parts.

[0111] In the embodiment, the small-diameter portion 48B of the armature 48 was described using the example where the outer diameter dimension d is the same along the axial direction. However, it is not limited to this, and for example, as shown in the third modified example in Figure 7, the outer circumferential surface of the small-diameter portion 64B of the armature 64 may be tapered. That is, the small-diameter portion 64B of the armature 64 may be an inclined surface that is inclined in a direction in which the diameter becomes smaller as it approaches the anchor 41. In this case, for example, the outer diameter dimension of the small-diameter portion 64B closest to the anchor 41 will be the same as the outer diameter dimension of the movable core (armature) which is the same along the entire axial direction (for example, the current product). On the other hand, the outer diameter dimension D of the large-diameter portion 64A can be, for example, about 1-2% larger than the outer diameter dimension of the small-diameter portion 64B closest to the anchor 41. Also, the axial length L1 of the large-diameter portion 64A can be smaller than the axial length L2 of the small-diameter portion 64B.

[0112] In the third modified example shown in Figure 7, the axial length L1 of the large-diameter portion 64A is made smaller than the axial length L2 of the small-diameter portion 64B. However, the axial lengths of the large-diameter portion 64A and the small-diameter portion 64B may be made the same, for example, as in the fourth modified example shown in Figure 8(A). Also, in the third modified example shown in Figure 7, the outer surface of the small-diameter portion 64B is a straight inclined surface. However, the small-diameter portion 64B may be a concave curved surface (concave curved surface), for example, as in the fifth modified example shown in Figure 8(B). Furthermore, the small-diameter portion 64B may be a convex curved surface (convex curved surface), for example, as in the sixth modified example shown in Figure 8(C).

[0113] In the fourth modified example shown in Figure 8(A), the center (central axis) of the large-diameter portion 64A and the center of the small-diameter portion 64B closest to the anchor 41 are concentric. However, as in the seventh modified example shown in Figure 9(D), the center (central axis) of the large-diameter portion 64A and the center of the small-diameter portion 64B closest to the anchor 41 may be eccentric. In this case, as in the eighth modified example shown in Figure 9(E), a portion of the circumferential direction of the large-diameter portion 64A and a portion of the circumferential direction of the small-diameter portion 64B may coincide axially. That is, the circumference (arc of the cross-section) of the small-diameter portion 64B closest to the anchor 41 may be inscribed with the circumference (arc of the cross-section) of the large-diameter portion 64A. In summary, as shown in the seventh modified example in Figure 9(D) and the eighth modified example in Figure 9(E), the small diameter portion 64B may be shifted radially relative to the large diameter portion 64A (the shape may be non-uniform on one side and the other side in the circumferential direction).

[0114] In the embodiments and modifications, the case in which the housing 36 and the cylinder 44, and the cylinder 44 and the yoke 39 are joined via brazing material has been described as an example. However, the invention is not limited to this, and for example, the housing 36 and the cylinder 44, and the cylinder 44 and the yoke 39 may be joined by welding.

[0115] In the embodiments and modifications, the case in which the anchor 41 is fixed by press-fitting into the fixing hole 39A of the yoke 39 has been described as an example. However, the invention is not limited to this, and the anchor may be fixed inside the yoke using, for example, screw fastening means such as screws, crimping means, etc.

[0116] In the embodiments and modifications, the case in which the anchor 41 and the yoke 39 are configured as separate components was used as an example. However, the invention is not limited to this, and for example, the anchor and the yoke may be configured as a single unit.

[0117] In the embodiments and modifications, the case in which one side of the cylinder 44 is fixed to the yoke 39 was described as an example. However, the invention is not limited to this, and for example, one side of the cylinder (jointing member) may be fixed to the anchor.

[0118] In the embodiments and modifications, the yoke 39 is provided with an other cylindrical portion 39H, and the tip side (the other axial side) of the other cylindrical portion 39H is fixed to the outer circumference of the cover member 51 by a crimping portion 39J. However, the invention is not limited to this, and for example, the annular portion of the yoke and the other cylindrical portion may be formed separately, and the other cylindrical portion may be formed integrally with the cover member.

[0119] In the embodiments and modifications, the case in which the solenoid 33 is configured as a proportional solenoid was described as an example. However, it is not limited to this, and for example, it may be configured as an ON / OFF type solenoid.

[0120] In the embodiments and modifications, a double-tube type shock absorber 1 consisting of an outer tube 2 and an inner tube 4 was used as an example. However, the invention is not limited to this, and may also be used in a damping force adjustable shock absorber consisting of a single-tube cylindrical member (cylinder), for example.

[0121] In the embodiments and modifications, the case in which the solenoid 33 is used as a variable damping force actuator for the shock absorber 1, that is, the case in which the pilot valve body 32 constituting the pilot valve of the damping force adjustment valve 18 is the object to be driven by the solenoid 33, was described as an example. However, the solenoid is not limited to this, and can be widely used as an actuator incorporated into various mechanical devices such as valves used in hydraulic circuits, that is, as a drive device that drives an object to be driven linearly.

[0122] The embodiments and variations are illustrative, and it goes without saying that partial substitutions or combinations of the configurations shown in different embodiments and variations are possible.

[0123] According to the embodiments and / or modifications described above (hereinafter simply referred to as "embodiments"), the movable core has a large-diameter portion and a small-diameter portion, and the small-diameter portion is provided on the fixed core side. Therefore, the small-diameter portion on the fixed core side of the movable core (i.e., the side facing the fixed core in the axial direction) is made into a small-diameter portion of the same diameter at all positions in the circumferential direction (a small-diameter portion of a circular periphery that is uniformly continuous in the circumferential direction), thereby ensuring axial attractive force. This ensures thrust of the movable core. On the other hand, on the large-diameter portion side of the movable core opposite the fixed core, the magnetic force becomes larger at the point where the gap between the large-diameter portion and the magnetic member provided on the outer diameter side of the movable core is smallest, depending on the manufacturing tolerance of the large-diameter portion. Therefore, a bias in the circumferential direction can be generated in the radial attractive force, and vibrations of the movable core can be absorbed. This makes it possible to achieve both securing thrust of the movable core and suppressing vibrations. Moreover, since the small-diameter portion can be formed by turning, for example, on a lathe, additional costs can be reduced.

[0124] According to this embodiment, the shaft portion is provided extending axially from the inner circumference of the movable core and the fixed core. Therefore, in addition to being able to provide a long shaft portion on the inner circumference of the movable core and the fixed core, the thrust of this shaft portion can be secured and vibration can be suppressed.

[0125] According to this embodiment, the shaft portion is equipped with bearings at both axial ends. Therefore, the bearings allow the shaft portion, which is displaced integrally with the movable core, to be smoothly and stably supported together with the movable core.

[0126] According to this embodiment, the second magnetoresistive section, which exerts the effect of moving the movable core radially, consists of a notch that cuts out one side of the movable core in the axial direction along the circumferential direction. Therefore, the notch that cuts out along the entire circumference of the movable core can generate a force that moves the movable core radially in the uncut portion. This ensures thrust for the movable core and suppresses vibration.

[0127] According to this embodiment, the gap between the large-diameter portion of the movable core and the magnetic member is larger than the gap between the bearing and the shaft. Therefore, contact between the large-diameter portion of the movable core and the magnetic member can be suppressed.

[0128] According to this embodiment, the axial length of the large-diameter section is smaller than the axial length of the small-diameter section. Therefore, by making the outer diameter of the small-diameter section the same as, for example, the outer diameter of a movable core that is the same diameter throughout its entire axial direction, the same thrust can be secured as in that configuration. Furthermore, by making the axial length of the large-diameter section smaller than the axial length of the small-diameter section, it is possible to suppress the reduction in thrust and the change in characteristics while obtaining a vibration suppression effect based on the bias of radial attractive force by the large-diameter section. This improves the robustness of the design.

[0129] According to this embodiment, the damping force adjustment valve of the damping force adjustment shock absorber is driven by a solenoid. Furthermore, the movable core of the solenoid has a large diameter section and a small diameter section, and the small diameter section is located on the fixed core side. This makes it possible to ensure the thrust of the solenoid and suppress vibrations, and to suppress vibrations (abnormal noises) caused by cavitation of the damping force adjustment valve driven by the solenoid. As a result, the stability of the damping force adjustment shock absorber can be improved.

[0130] According to this embodiment, the movable element of the damping force adjustment mechanism has a large-diameter portion and a small-diameter portion, and the small-diameter portion is provided on the stator side. Therefore, it is possible to achieve both securing the thrust of the movable element and suppressing vibration, and vibration (abnormal noise) caused by cavitation of the control valve controlled by the movable element can be suppressed.

[0131] According to the embodiment, the radial gap between the movable core and the magnetic member is larger on the fixed core side compared to other areas. Therefore, on the fixed core side (i.e., the side where the movable core and the fixed core face each other in the axial direction), the radial gap is the same width throughout the circumferential direction, thereby ensuring axial attractive force. This ensures thrust for the movable core. On the other hand, on the side opposite the fixed core (opposite the fixed core), the magnetic force is greater in the area where the radial gap is smallest due to manufacturing tolerances. Therefore, a circumferential bias can be created in the radial attractive force, absorbing vibrations of the movable core. This makes it possible to achieve both securing thrust for the movable core and suppressing vibrations.

[0132] According to the embodiment, the diameter of the movable core is the same, and the inner diameter of the magnetic member is larger on the fixed core side compared to other parts. Therefore, by increasing the inner diameter of the magnetic member on the fixed core side, the radial gap between the movable core and the magnetic member on the fixed core side can be increased compared to other parts.

[0133] Furthermore, the present invention is not limited to the embodiments described above, and various modifications are included. For example, the embodiments described above are described in detail to make the present invention easier to understand, and are not necessarily limited to those having all the configurations described. Also, it is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. In addition, it is possible to add, delete, or replace parts of the configuration of each embodiment with other configurations.

[0134] This application claims priority under Japanese Patent Application No. 2022-022763, filed on 17 February 2022. The entire disclosure of Japanese Patent Application No. 2022-022763, filed on 17 February 2022, including the specification, claims, drawings, and abstract, is incorporated into this application by reference. [Explanation of Symbols]

[0135] 1: Shock absorber (adjustable damping shock absorber), 2: Outer cylinder, 4: Inner cylinder, 5: Piston, 8: Piston rod, 17: Damping force adjustment mechanism, 18: Damping force adjustment valve (control valve), 32: Pilot valve body (control valve), 33: Solenoid, 34A: Coil, 36, 63: Housing (magnetic component), 38: First bush (bearing), 41: Anchor (fixed core, stator), 43: Second bush (bearing), 48, 61, 62, 64: Armament (movable core, movable element, first magnetic resistance section), 48A, 61A, 62A, 64A: Large diameter section, 48B, 61B, 62B, 64B: Small diameter section (notch, second magnetic resistance section), 49: Actuating pin (shaft section)

Claims

1. A solenoid, said solenoid is A coil that generates a magnetic field when an electric current is passed through it, A movable iron core, at least a portion of which is located on the inner circumference side of the coil and is provided to be movable in the axial direction of the coil, A fixed iron core facing the movable iron core in the axial direction, with a cylindrical outer circumferential projection formed thereon that protrudes toward the movable iron core, A magnetic member is disposed between the inner circumference of the coil and the movable iron core, and has a first end facing the outer circumferential protrusion. It comprises a shaft portion that is displaced integrally with the movable core, The movable core has a large diameter portion and a small diameter portion. The small diameter portion is provided on the fixed core side. The axial length of the large-diameter portion is formed to be smaller than the axial length of the small-diameter portion. The axial length of the small-diameter portion is formed to be longer than the distance from the axial end on the fixed core side to the first end when the coil is energized. The gap between the outer circumference of the large-diameter portion and the inner circumference of the magnetic member is formed to be smaller than the gap between the outer circumference of the small-diameter portion and the inner circumference of the fixed iron core. The large-diameter portion has an axially elongated portion (L1) that extends in the axial direction, thus forming a solenoid.

2. In the solenoid according to claim 1, The shaft portion is a solenoid, provided by extending axially from the inner circumference of the movable core and the inner circumference of the fixed core.

3. A solenoid, wherein the solenoid is A coil that generates a magnetic field when an electric current is passed through it, A movable iron core, at least a portion of which is located on the inner circumference side of the coil and is provided to be movable in the axial direction of the coil, A fixed iron core facing the movable iron core in the axial direction, with a cylindrical outer circumferential projection formed thereon that protrudes toward the movable iron core, A magnetic member is disposed between the inner circumference of the coil and the movable iron core, and has a first end facing the outer circumferential protrusion. It comprises a shaft portion that is displaced integrally with the movable core, The movable core has a large diameter portion and a small diameter portion. The small diameter portion is provided on the fixed core side. The axial length of the large-diameter portion is formed to be smaller than the axial length of the small-diameter portion. The axial length of the small-diameter portion is formed to be longer than the distance from the axial end on the fixed core side to the first end when the coil is energized. The gap between the outer circumference of the large-diameter portion and the inner circumference of the magnetic member is formed to be smaller than the gap between the outer circumference of the small-diameter portion and the inner circumference of the fixed iron core. The shaft portion is a solenoid equipped with bearings at both axial ends of the shaft portion.

4. In the solenoid described in claim 3, The magnetic member is provided on the outer circumference of the movable core. A solenoid in which the gap between the large-diameter portion of the movable core and the magnetic member is larger than the gap between the bearing and the shaft portion.

5. A damping force adjustable shock absorber, the damping force adjustable shock absorber is, A cylinder in which the working fluid is sealed, A piston inserted into the cylinder and dividing the inside of the cylinder into a rod side chamber and a bottom side chamber, A piston rod, one end of which is connected to the piston and the other end of which extends to the outside of the cylinder, A passage through which the flow of the working fluid is generated by the extension and retraction of the piston rod, The flow path includes a damping force adjustment valve driven by a solenoid, The solenoid mentioned above is A coil that generates a magnetic field when an electric current is passed through it, A movable iron core, at least a portion of which is located on the inner circumference side of the coil and is provided to be movable in the axial direction of the coil, A fixed iron core facing the movable iron core in the axial direction, with a cylindrical outer circumferential projection formed thereon that protrudes toward the movable iron core, The system includes a magnetic member disposed between the inner circumference of the coil and the movable iron core, with a first end formed facing the outer circumferential protrusion, The movable core has a large diameter portion and a small diameter portion. The small diameter portion is provided on the fixed core side. The axial length of the large-diameter portion is formed to be smaller than the axial length of the small-diameter portion. The axial length of the small-diameter portion is formed to be longer than the distance from the axial end on the fixed core side to the first end when the coil is energized. The gap between the outer circumference of the large-diameter portion and the inner circumference of the magnetic member is formed to be smaller than the gap between the outer circumference of the small-diameter portion and the inner circumference of the fixed iron core. The large-diameter portion has an axially extended axial length portion (L1), and is a damping force adjustable shock absorber.

6. A damping force adjustment mechanism, A coil that generates a magnetic field when an electric current is passed through it, A movable element located on the inner circumference side of the coil and movably mounted in the axial direction of the coil, A stator facing the movable element in the axial direction and having a cylindrical outer circumferential projection that protrudes toward the movable element, A control valve controlled by the axial movement of the movable element, The magnetic member is positioned between the inner circumference of the coil and the movable element, and has a first end portion facing the outer circumferential projection. The movable element has a large diameter portion and a small diameter portion. The small diameter portion is provided on the stator side. The axial length of the large-diameter portion is formed to be smaller than the axial length of the small-diameter portion. The axial length of the small-diameter portion is formed to be longer than the distance from the axial end on the stator side to the first end when the coil is energized. The gap between the outer circumference of the large-diameter portion and the inner circumference of the magnetic member is formed to be smaller than the gap between the outer circumference of the small-diameter portion and the inner circumference of the stator. The large-diameter portion has an axially extended axial length portion (L1), which is a damping force adjustment mechanism.

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