solenoid

Abstract

The present invention provides a solenoid capable of improving the thrust of a movable element, a damping force adjustment mechanism, and a damping force adjustable shock absorber. [Solution] The solenoid 33 comprises a coil 34A, an armature 48, an anchor 41, a housing 36, a yoke 39, and a cover 51. The coil 34A is wound in a ring shape and generates a magnetic force when energized. The armature 48 is provided so as to be movable in the direction of the winding axis of the coil 34A. The anchor 41 is provided on one side in the direction of movement of the armature 48. The housing 36 houses the armature 48. The yoke 39 is to which the anchor 41 is attached. The cover 51 covers the coil 34A. At least one of the armature 48, anchor 41, housing 36, yoke 39, and cover 51 is not made of a single material, but is made of partially separate members 61A, 61B, 61C, 61D, 61E.

Description

Technical Field

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

Background Art

[0002] Vehicles such as four-wheeled automobiles are each provided with a shock absorber (damper) between the vehicle body (sprung) side and each wheel (unsprung) side. As such a vehicle shock absorber, for example, a damping force adjustable hydraulic shock absorber that variably adjusts the damping force according to traveling conditions, vehicle behavior, and the like is known. The damping force adjustable hydraulic shock absorber constitutes a semi-active suspension of a vehicle.

[0003] The damping force adjustable hydraulic shock absorber variably adjusts the generated damping force by, for example, adjusting the valve opening pressure of a damping force adjustment 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 actuator in which the saturation magnetic flux density of an extending portion extending from the main body portion of a fixed core toward a plunger is set lower than that of the main body portion. Patent Document 2 describes an electromagnetic drive device in which a demagnetized portion obtained by melting a demagnetizing element is formed in a magnetic flux limiting portion of a fixed core.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of Invention

Problems to be Solved by the Invention

[0005] According to the conventional art, since the magnetic flux density of the magnetically saturated region of the stator (fixed core) is reduced, the thrust of the mover (plunger) may decrease due to magnetic saturation.

[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 improve the thrust of a movable element. [Means for solving the problem]

[0007] One embodiment of the present invention is a solenoid, a damping force adjustment mechanism, or a damping force adjustment type shock absorber, comprising: a coil wound in an annular shape and generating a magnetic force when energized; a movable element made of a magnetic material and movably mounted in the direction of the winding axis of the coil; a stator provided on one side in the direction of movement of the movable element; a housing in which the movable element is housed; a yoke to which the stator is attached; and a cover that constitutes a magnetic circuit and covers the coil, wherein at least one of the movable element, the stator, the housing, the yoke, and the cover is not made of a single material but is made of partially different materials.

[0008] Furthermore, one embodiment of the present invention is a solenoid comprising: a coil wound in a ring shape and generating a magnetic force when energized; a movable element made of a magnetic material and movably mounted in the direction of the winding axis of the coil; a stator provided on one side in the direction of movement of the movable element; a housing in which the movable element is housed; a yoke to which the stator is attached; and a cover that constitutes a magnetic circuit and covers the coil, wherein at least one of the movable element, the stator, the housing, the yoke, and the cover is made of a single material, and the single material is a high saturation magnetic flux density material, a high permeability material, or a pure iron-based soft magnetic material. [Effects of the Invention]

[0009] According to one embodiment of the present invention, the thrust of the movable element can be improved. [Brief explanation of the drawing]

[0010] [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 mechanism 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 explanatory diagram (corresponding to the right half of Figure 3) showing the magnetic flux concentration point of the solenoid and the part that is a separate component. [Figure 5] This characteristic diagram shows seven examples of the relationship between the stroke of a movable element and thrust. [Figure 6] This characteristic diagram shows five other examples of the relationship between the stroke of a movable element and thrust. [Figure 7] This characteristic diagram shows four other examples of the relationship between the stroke of a movable element and thrust. [Modes for carrying out the invention]

[0011] The following description will refer to the attached drawings and use as an example the case in which the solenoid, damping force adjustment mechanism, and damping force adjustable shock absorber according to the embodiment are used in a damping force adjustable hydraulic shock absorber incorporated into a vehicle such as a four-wheeled automobile.

[0012] 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, and a damping force adjustment mechanism 17.

[0013] 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.

[0014] 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 oil 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 an oil liquid; for example, water mixed with additives may also be used.

[0015] An annular reservoir chamber A is formed between the inner cylinder 4 and the outer cylinder 2. Gas is sealed inside reservoir chamber A along with the oil. This gas may be air at atmospheric pressure, or a gas such as compressed nitrogen gas may be used. Reservoir chamber A compensates for the entry and exit of the piston rod 8. At a point along the length (axial direction) of the inner cylinder 4, an oil hole 4A is drilled radially, which constantly connects the rod-side oil chamber B to the annular oil chamber D.

[0016] The piston 5 is slidably mounted within the inner cylinder 4. The piston 5 is inserted into the inner cylinder 4, dividing the inside of the inner cylinder 4 into two chambers: a rod-side oil chamber B (rod-side chamber) and a bottom-side oil chamber C (bottom-side chamber). Multiple oil passages 5A and 5B are formed in the piston 5, spaced apart in the circumferential direction, enabling communication between the rod-side oil chamber B and the bottom-side oil chamber C.

[0017] Here, the lower end face of the piston 5 is provided with an extension-side disk valve 6. The extension-side disk valve 6 opens when the pressure in the rod-side oil chamber B exceeds a relief set pressure as the piston 5 slides upward during the extension stroke of the piston rod 8, and relieves the pressure at this time to the bottom-side oil chamber C side via each oil passage 5A. The relief set pressure is set to a pressure higher than the valve opening pressure when the damping force adjustment mechanism 17 is set to the hard mode.

[0018] The upper end face of the piston 5 is provided with 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 at other times. The check valve 7 allows the hydraulic fluid in the bottom-side oil chamber C to flow through each oil passage 5B toward the rod-side oil chamber B, and blocks the hydraulic fluid from flowing in the opposite direction. The valve opening pressure of the check valve 7 is set to a pressure lower than the valve opening pressure when the damping force adjustment mechanism 17 is set to the soft mode, and substantially no damping force is generated. The expression "substantially no damping force is generated" refers to a force equal to or lower than the friction of the piston 5 and the seal member 10, which does not affect the motion of the vehicle.

[0019] The piston rod 8 extends in the inner cylinder 4 in the axial direction (the vertical direction in Fig. 1). The lower end side of the piston rod 8 is inserted into the inner cylinder 4. The piston rod 8 is fixedly attached to the piston 5 by a nut 8A or the like. The upper end side of the piston rod 8 protrudes to the outside of the outer cylinder 2 and the inner cylinder 4 via a rod guide 9. That is, the piston rod 8 has its lower side (lower end) serving as one side (one end) connected to the piston 5, and its upper side (upper end) serving as the other side (the other end) extending to the outside of the inner cylinder 4 and the outer cylinder 2. Note that the lower end of the piston rod 8 may be further extended to protrude outward from the bottom portion (for example, the bottom cap 3) side to form a so-called double-rod structure.

[0020] 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.

[0021] 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.

[0022] 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 part of the flow path through which the working fluid flows as the piston rod 8 moves. 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] The damping force adjustment mechanism 17 generates damping force by controlling the flow of the working fluid (oil) produced by the sliding of the piston 5 inside the cylinder (inner cylinder 4), and also variably adjusts the damping force generated by the shock absorber 1. In Figure 2, the damping force adjustment mechanism 17 shows the state in which the armature 48, operating pin 49, and pilot valve body 32 have moved to the left side of Figure 2 by applying external current to the coil 34A of the solenoid 33 (for example, control to generate a hard damping force). In other words, the damping force adjustment mechanism 17 in Figure 2 shows the closed valve state in which the pilot valve body 32 is seated on the valve seat portion 26E of the pilot body 26.

[0028] 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) is provided to protrude 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 a damping force adjustment valve 18 (main valve 23, pilot valve body 32). Furthermore, the generated damping force is variably adjusted by adjusting the opening pressure of the damping force adjustment valve 18 (main valve 23, pilot valve body 32) with a solenoid 33 used as a variable damping force actuator.

[0029] Thus, 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. For this purpose, the damping force adjustment mechanism 17 is composed of a damping force adjustment valve 18 and a solenoid 33. The damping force adjustment valve 18 generates 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.

[0030] In other words, the damping force adjustment valve 18 is a valve whose opening and closing operation is adjusted by a solenoid 33, and is located in a passage (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 (pilot valve body 32, and consequently the main valve 23). In this case, the opening pressure of the damping force adjustment valve 18 (pilot valve body 32, and consequently the main valve 23) 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.

[0031] Here, the damping force adjustment valve 18 is composed of a valve case 19, a connecting pipe 20, and a valve member 21. The valve case 19 is formed in a substantially cylindrical shape, with its base end fixed around the opening 2B of the outer cylinder 2, and its tip end protruding radially outward from the outer cylinder 2. The connecting pipe 20 has its base end fixed to the connection port 12C of the intermediate cylinder 12, and its tip end is an annular flange portion 20A, which is disposed inside the valve case 19 with a gap. The valve member 21 is in contact with the flange portion 20A of the connecting pipe 20.

[0032] 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).

[0033] 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, which serve as radial oil passages to connect the oil chamber 19C and the reservoir chamber A. In this embodiment, the notches 22A for forming oil passages are provided on the spacer 22. 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.

[0034] 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 side 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. Each oil passage 21B of the valve member 21 serves as a flow path for pressurized oil, with a flow rate corresponding to the opening 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.

[0035] The main valve 23 is composed of a disc valve. The inner circumference of the main valve 23 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 receiving pressure from the oil passage 21B side (annular oil chamber D side) of the valve member 21 and separating from the annular valve seat 21D. 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 at this time is variably adjusted according to the opening degree of the main valve 23.

[0036] The pilot pin 24 is formed in a stepped cylindrical shape, with an annular large-diameter portion 24A provided in the axial middle. 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. In this state, the large-diameter portion 24A of the pilot pin 24 sandwiches the main valve 23 between itself and the valve member 21.

[0037] 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. 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.

[0038] 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.

[0039] 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.

[0040] 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).

[0041] 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 supplied to the solenoid 33.

[0042] In other words, the pilot valve (pilot body 26 and pilot valve element 32), which acts as a control valve, is controlled by the axial movement of the operating pin 49 of the solenoid 33 (more specifically, the armature 48 fixed to the operating pin 49). A flange portion 32A, which acts as a spring seat, is formed around the entire circumference of the base end of the pilot valve element 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 element 32 is displaced to the fully open position, which is furthest from the valve seat portion 26E.

[0043] 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 1 and 2, as well as Figure 3. Note that in Figure 3, the right side in the left-right direction of Figure 2 is considered the upper side, and the reference numerals are assigned accordingly. That is, the left-right direction in Figures 1 and 2 corresponds to the up-down direction in Figures 3 and 4.

[0044] 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 which serves as a storage member (magnetic member), a yoke 39 which serves as a case member, an anchor 41 which serves as a stator (fixed iron core), a cylinder 44 which serves as a connecting member (non-magnetic ring), an armature 48 which serves as a movable element (movable iron core), an operating pin 49 which serves as a shaft, and a cover 51 which serves as a cover member.

[0045] 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).

[0046] 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.

[0047] 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).

[0048] The housing 36 constitutes a first fixed iron core (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 as a storage section, a lid portion 36B, and a small-diameter cylinder portion 36C. The storage cylinder portion 36A extends in the direction of the winding axis of the molded coil 34 (coil 34A), and is open at one end (left side in Figure 2, lower side in Figure 3). The lid portion 36B closes the other end of the storage cylinder portion 36A (right side in Figure 2, upper side in Figure 3). The small-diameter cylinder portion 36C is located on the opening side (one side) of the storage cylinder portion 36A and is formed to reduce the outer diameter of the storage cylinder portion 36A.

[0049] 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. 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 has an opening at one end in the axial direction, and the armature 48 is housed therein. 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.

[0050] On the other hand, the lid portion 36B of the housing 36 is formed integrally 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. The fitting cylinder portion 51A of the cover 51 is fitted to 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 has 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 (first bearing) for slidably supporting the operating pin 49.

[0051] Furthermore, the lid portion 36B of the housing 36 is positioned opposite the lid plate 51B of the cover 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 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.

[0052] 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). That is, the yoke 39 is formed using a magnetic material (magnetic body) similar to the housing 36. The yoke 39 is composed of 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 being 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.

[0053] In other words, the yoke 39 has a fixing hole 39A, and the anchor 41 is positioned within the fixing hole 39A. Furthermore, an inward-facing flange portion 39D is provided within 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 the axial end face (one end face) of the cylinder 44. In addition, the outer circumference of the 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 portion 39C).

[0054] 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 main valve 23), an other-side section 39H extending from the outer circumference of the annular section 39B toward the other axial side (towards the cover 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 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 section 34E of the molded coil 34 to the outside of the other-side section 39H.

[0055] 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, 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.

[0056] 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 stator (second fixed core) fixed in the fixing hole 39A of the yoke 39 by means of press-fitting or other means. The anchor 41, like the housing 36 (first fixed core) 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 in the axial direction at its center. One axial side of the anchor 41 (the side facing the cap 31 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.

[0057] On the other axial side of the anchor 41 (the other side facing 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.

[0058] Specifically, the outer circumferential protrusion 41C, also called the corner portion, protrudes cylindrically from the outer circumferential side of the anchor 41 toward the other axial direction. The outer circumferential surface of the outer circumferential protrusion 41C (the outer circumferential 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). The anchor 41 also has an annular inner circumferential protrusion 41F that is located radially inward and protrudes axially toward the armature 48 side. Between the outer circumferential protrusion 41C and the inner circumferential protrusion 41F of the anchor 41, that is, in the recessed portion 41B of the anchor 41, an annular intermediate protrusion 41G with a roughly triangular cross-section is formed.

[0059] 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).

[0060] 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.

[0061] As shown in Figure 3, a second bush 43, which serves as a bearing (second 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, a pilot body 26, a return spring 28, a disc valve 29, a retaining plate 30, and a cap 31 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.

[0062] 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.

[0063] 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.

[0064] The armature 48, also called a plunger, is positioned between the housing cylinder 36A of the housing 36 and the recess 41B of the anchor 41. The armature 48 is a movable element (movable core) made of a magnetic material that is movable 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 36A of the housing 36, the recess 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 36A of the housing 36 and the recess 41B of the anchor 41. That is, the armature 48 is positioned on the inner circumference side of the housing cylinder 36A of the housing 36 and the recess 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.

[0065] 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 towards the recess 41B of the anchor 41. The armature 48 has an annular groove 48A with a substantially triangular cross-section that corresponds to the intermediate protrusion 41G of the anchor 41.

[0066] The actuation pin 49 is the shaft portion that transmits the thrust of the armature 48 to the pilot valve body 32, 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.

[0067] 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).

[0068] The cover 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 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 51 is formed as a whole in the shape of a covered cylinder, 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).

[0069] Here, the fitting cylindrical portion 51A of the cover 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 51 has an annular flange portion 51C on its outer circumference that extends radially outward from the fitting cylindrical portion 51A, 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 51 are pre-assembled (sub-assembled) with the molded coil 34 built inside, as shown in Figure 3.

[0070] 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 51, the lid portion 36B of the housing 36 is fitted into the fitting cylindrical portion 51A of the cover 51. This allows for the transfer of magnetic flux between the fitting cylindrical portion 51A of the cover 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 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 51 (fitting cylindrical portion 51A). This prevents rainwater and dust containing mud from entering the space between the cover 51 and the molded coil 34, the space between the housing 36 and the molded coil 34, and even the space between the housing 36 and the cover 51.

[0071] As shown in Figure 3, the yoke 39 and cover 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 cylindrical portion 39G on one side of the yoke 39.

[0072] 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.

[0073] Incidentally, conventional solenoids have a low magnetic flux density in the stator's magnetic saturation region. As a result, thrust performance may decrease due to magnetic saturation inside the movable element, housing, and plate. Therefore, in this embodiment, the magnetic material components of the solenoid are not made of a single material, but rather partially made of a material with high permeability and high saturation magnetic flux density. This makes it possible to mitigate magnetic saturation and improve thrust in this embodiment. Furthermore, by using dissimilar materials in parts, costs can be reduced compared to changing the material of the entire component. These points will be explained in detail below.

[0074] 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 (pilot valve body 32, and consequently the main valve 23). The damping force adjustment valve 18 (pilot valve body 32, and consequently the main valve 23) is located in the flow path where the working fluid flow is generated by the expansion and contraction of the piston rod 8, that is, between the annular oil chamber D and the reservoir chamber A. The damping force adjustment valve 18 (pilot valve body 32, and consequently the main valve 23) is driven by a solenoid 33.

[0075] Furthermore, 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, a housing 36, a yoke 39, a cover 51, and a damping force adjustment valve 18 (more specifically, a pilot valve body 32, and consequently, a main valve 23) as a control valve. The damping force adjustment valve 18 (pilot valve body 32, and consequently, the main valve 23) is controlled by the axial movement of the armature 48, which is fixed to the operating pin 49. Also, as shown in Figure 3, the solenoid 33 comprises a coil 34A, an armature 48, an anchor 41, a housing 36, a yoke 39, and a cover 51.

[0076] The coil 34A is wound in a ring shape and generates magnetic force (magnetic flux, magnetic field) when energized. The armature 48 is made of a magnetic material. The armature 48 is mounted to be movable in the direction of the winding axis of the coil 34A. The anchor 41 is mounted on one side of the armature 48 in the direction of movement (the lower side in the vertical direction of Figure 3). The housing 36 houses the armature 48. The housing 36 is mounted radially between the coil 34A and the armature 48. The housing 36 is open on one end of the coil 34A in the axial direction (the lower side in the vertical direction of Figure 3). The anchor 41 is attached to the yoke 39. The cover 51 covers the coil 34A. The cover 51 constitutes a magnetic circuit.

[0077] The solenoid 33, together with the pilot valve body 32, constitutes a solenoid valve (pressure control valve). When current is passed through the coil 34A of the solenoid 33, a magnetic flux is generated, and this flux passes through a magnetic circuit consisting of the armature 48, anchor 41, cover 51, housing 36, and yoke 39, causing the armature 48 to be attracted to the anchor 41. This becomes the thrust of the armature 48, which controls the opening and closing of the pilot valve body 32.

[0078] In this embodiment, at least one of the armature 48, anchor 41, housing 36, yoke 39, and cover 51 is not made of a single material, but is partially composed of separate components 61A, 61B, 61C, 61D, and 61E. Figure 4 shows the magnetic flux concentration areas and separate components of the solenoid 33. The areas A, B, C, and D enclosed by the dashed lines in Figure 4 correspond to the magnetic flux concentration areas. The areas marked with dots in Figure 4 correspond to the separate components 61A, 61B, 61C, 61D, and 61E. That is, areas A, B, C, and D in Figure 4 are prone to magnetic saturation.

[0079] Therefore, in this embodiment, the parts corresponding to sections A, B, C, and D, where magnetic saturation is likely to occur, are made of separate members 61A, 61B, 61C, 61D, and 61E, for example, a metal material having a high saturation magnetic flux density. This eliminates magnetic saturation and improves thrust. Figure 4 illustrates a case where the armature 48, anchor 41, housing 36, yoke 39, and cover 51 are not made of a single material, but are partially made of separate members 61A, 61B, 61C, 61D, and 61E. However, this is not an exception, and although not shown in the figure, for example, four, three, two, or one of the five parts of the armature 48, anchor 41, housing 36, yoke 39, and cover 51 may be partially made of a separate material (a metal material with a high saturation magnetic flux density).

[0080] As shown in Figure 4, the anchor 41 has an outer peripheral protrusion 41C which serves as a cylindrical portion into which the armature 48 fits. The outer peripheral protrusion 41C is a separate component 61A from the anchor main component 62A, which is the part of the anchor 41 other than the outer peripheral protrusion 41C, and is made of a different material. In this case, the separate anchor component 61A of the anchor 41 is made of a material with higher magnetic permeability or higher saturation magnetic flux density than the anchor main component 62A, which is the main component (stator main component) of the anchor 41. The anchor main component 62A can be made of, for example, carbon steel (S10C), which is a typical metallic material. In contrast, the separate anchor component 61A can be made of, for example, permendur, a pure iron-based soft magnetic material (for example, a pure iron-based soft magnetic material that satisfies JIS standard C2504), which is a high saturation magnetic flux density material, or permalloy (for example, 45% Ni), which is a high magnetic permeability material. For example, the main anchor member 62A may be made of a pure iron-based soft magnetic material, and the separate anchor member 61A may be made of Permendur. In other words, for example, the saturation magnetic flux density of the separate anchor member 61A shall be 1.1 times or more that of the main anchor member 62A. Also, the permeability of the separate anchor member 61A shall be 1.5 times or more that of the main anchor member 62A.

[0081] The anchor 41 can be formed, for example, by bonding, welding, or brazing an anchor main member 62A and an anchor separate member 61A, each molded from different materials. Alternatively, the anchor 41 may be formed by press-fitting the anchor separate member 61A into the anchor main member 62A, each molded from different materials. For example, the anchor 41 may be formed by fitting an annular (ring-shaped) anchor separate member 61A into the anchor main member 62A. Furthermore, the anchor 41 may be formed by integrally molding the anchor main member 62A and the anchor separate member 61A using, for example, additive manufacturing technology (3D printer).

[0082] The armature 48 has a groove 48A as an opposing portion that faces the anchor 41. The groove 48A is a separate component 61B from the armature main component 62B, which is the part of the armature 48 other than the groove 48A, and is made of a different material. In this case, the armature separate component 61B, which is a separate component of the armature 48, is made of a material with higher magnetic permeability or higher saturation magnetic flux density than the armature main component 62B, which is the main component (movable element main component) of the armature 48. The armature main component 62B can be made of, for example, carbon steel (S10C), which is a typical metallic material. In contrast, the armature separate component 61B can be made of, for example, a high saturation magnetic flux density material such as Permendur, a pure iron-based soft magnetic material (for example, a pure iron-based soft magnetic material that satisfies JIS standard C2504), or a high magnetic permeability material such as Permalloy (for example, 45% Ni). For example, the main armature member 62B may be made of a pure iron-based soft magnetic material, and the secondary armature member 61B may be made of Permendur. In other words, for example, the saturation magnetic flux density of the secondary armature member 61B shall be 1.1 times or more that of the main armature member 62B. Also, the permeability of the secondary armature member 61B shall be 1.5 times or more that of the main armature member 62B.

[0083] The armature 48 can be formed, for example, by bonding, welding, or brazing an armature main member 62B and an armature sub-member 61B, which are molded from different materials. Alternatively, the armature 48 may be formed by press-fitting the armature sub-member 61B into the armature main member 62B, which are molded from different materials. For example, the armature 48 may be formed by fitting an annular (ring-shaped) armature sub-member 61B into the armature main member 62B. Furthermore, the armature 48 may be formed by molding the armature main member 62B and the armature sub-member 61B as a single unit using, for example, additive manufacturing technology (3D printer).

[0084] The yoke 39 has an inward-facing flange portion 39D that serves as a stator contact portion that contacts the anchor 41. The inward-facing flange portion 39D is a separate component 61C, i.e., made of a different material, from the yoke main component 62C, which is the part of the yoke 39 other than the inward-facing flange portion 39D. In this case, the yoke separate component 61C, which is a separate component of the yoke 39, is made of a material with higher magnetic permeability or higher saturation magnetic flux density than the yoke main component 62C, which is the main component of the yoke 39. The yoke main component 62C can be made of, for example, carbon steel (S10C), which is a typical metallic material. In contrast, the yoke separate component 61C can be made of, for example, a high saturation magnetic flux density material such as Permendur, a pure iron-based soft magnetic material (for example, a pure iron-based soft magnetic material that satisfies JIS standard C2504), or a high magnetic permeability material such as Permalloy (for example, 45% Ni). For example, the main yoke member 62C may be made of a pure iron-based soft magnetic material, and the separate yoke member 61C may be made of Permendur. In other words, for example, the saturation magnetic flux density of the separate yoke member 61C shall be 1.1 times or more that of the main yoke member 62C. Also, the permeability of the separate yoke member 61C shall be 1.5 times or more that of the main yoke member 62C.

[0085] The yoke 39 can be formed, for example, by bonding, welding, or brazing a yoke main member 62C and a yoke separate member 61C, which are molded from different materials. Alternatively, the yoke 39 may be formed by press-fitting the yoke separate member 61C into the yoke main member 62C, which are molded from different materials. For example, the yoke 39 may be formed by fitting an annular (ring-shaped) yoke separate member 61C into the yoke main member 62C. Furthermore, the yoke 39 may be formed by molding the yoke main member 62C and the yoke separate member 61C as a single unit using, for example, additive manufacturing technology (3D printer).

[0086] The housing 36 has a cover contact portion 36D that contacts the cover 51. The cover contact portion 36D corresponds to the connection portion between the storage cylinder portion 36A and the lid portion 36B. The cover contact portion 36D is a separate component 61D, i.e., made of a different material (different material), from the housing main component 62D, which is the part of the housing 36 other than the cover contact portion 36D. In this case, the housing separate component 61D, which is a separate component of the housing 36, is made of a material with higher magnetic permeability or higher saturation magnetic flux density than the housing main component 62D, which is the main component of the housing 36. The housing main component 62D can be made of, for example, carbon steel (S10C), which is a metal material. In contrast, the housing separate component 61D can be made of, for example, permendur, a pure iron-based soft magnetic material (for example, a pure iron-based soft magnetic material that satisfies JIS standard C2504), which is a high saturation magnetic flux density material, or permalloy (for example, 45% Ni), which is a high magnetic permeability material. For example, the main housing component 62D may be made of a pure iron-based soft magnetic material, and the separate housing component 61D may be made of Permendur. In other words, for example, the saturation magnetic flux density of the separate housing component 61D shall be 1.1 times or more that of the main housing component 62D. Also, the permeability of the separate housing component 61D shall be 1.5 times or more that of the main housing component 62D.

[0087] The housing 36 can be formed, for example, by bonding, welding, or brazing a housing main member 62D and a housing separate member 61D, each molded from different materials. Alternatively, the housing 36 may be formed by press-fitting the housing separate member 61D into the housing main member 62D, each molded from different materials. For example, the housing 36 may be formed by fitting an annular (ring-shaped) housing separate member 61D into the housing main member 62D. Furthermore, the housing 36 may be formed by integrally molding the housing main member 62D and the housing separate member 61D using, for example, additive manufacturing technology (3D printer). Although not shown in the figures, in order to ensure airtightness inside the housing, the inner diameter side of the housing may be molded from metal, and only the outer side may be fitted as a ring-shaped member made of a material having high magnetic permeability or high saturation magnetic flux density. In this case, the inner diameter side of the housing becomes the housing main member, and the outer diameter side of the housing becomes the housing separate member.

[0088] The cover 51 has a housing contact portion 51E that contacts the housing 36. The housing contact portion 51E corresponds to the connection portion between the fitting cylinder portion 51A and the cover plate 51B (more specifically, the flange portion 51C). The housing contact portion 51E is a separate component 61E from the main cover component 62E, which is the part of the cover 51 other than the housing contact portion 51E, and is made of a different material. In this case, the separate cover component 61E of the cover 51 is made of a material with higher magnetic permeability or higher saturation magnetic flux density than the main cover component 62E of the cover 51. The main cover component 62E can be made of, for example, carbon steel (S10C), which is a metal material. In contrast, the cover component 61E can be made of, for example, Permendur, a pure iron-based soft magnetic material (for example, a pure iron-based soft magnetic material that satisfies JIS standard C2504), or Permalloy (for example, 45% Ni), which is a high-saturation magnetic flux density material. Alternatively, for example, the main cover component 62E may be made of a pure iron-based soft magnetic material, and the cover component 61E may be made of Permendur. In other words, for example, the saturation magnetic flux density of the cover component 61E should be 1.1 times or more that of the main cover component 62E. Also, the permeability of the cover component 61E should be 1.5 times or more that of the main cover component 62E.

[0089] The cover 51 can be formed, for example, by bonding, welding, or brazing a main cover member 62E and a separate cover member 61E, each molded from different materials. Alternatively, the cover 51 may be formed by press-fitting the separate cover member 61E into the main cover member 62E, each molded from different materials. For example, the cover 51 may be formed by fitting an annular (ring-shaped) separate cover member 61E into the main cover member 62E. Furthermore, the cover 51 may be formed by integrally molding the main cover member 62E and the separate cover member 61E using, for example, additive manufacturing technology (3D printer).

[0090] Figure 5 shows the relationship between the stroke and thrust of the movable element (armature). In this case, Figure 5 shows five examples in which one of the five components—armature 48, anchor 41, housing 36, yoke 39, and cover 51—is partially made of a different material, and two examples in which all components are made of a single material. In Figure 5, characteristic line 71 shows the characteristics when only the armature 48 is partially made of a different material. In this case, the main armature component 62B is made of a pure iron-based soft magnetic material, and the separate armature component 61B is made of Permendur, a high saturation magnetic flux density material. In Figure 5, characteristic line 72 shows the characteristics when only the anchor 41 is partially made of a different material. In this case, the main anchor component 62A is made of a pure iron-based soft magnetic material, and the separate anchor component 61A is made of Permendur, a high saturation magnetic flux density material.

[0091] In Figure 5, characteristic curve 73 shows the characteristics when only the housing 36 is partially constructed from a different material. In this case, the main housing member 62D is made of a pure iron-based soft magnetic material, and the separate housing member 61D is made of Permendur, a high saturation magnetic flux density material. In Figure 5, characteristic curve 74 shows the characteristics when only the yoke 39 is partially constructed from a different material. In this case, the main yoke member 62C is made of a pure iron-based soft magnetic material, and the separate yoke member 61C is made of Permendur, a high saturation magnetic flux density material. In Figure 5, characteristic curve 75 shows the characteristics when only the cover 51 is partially constructed from a different material. In this case, the main cover member 62E is made of a pure iron-based soft magnetic material, and the separate cover member 61E is made of Permendur, a high saturation magnetic flux density material. In Figure 5, characteristic curve 76 shows the characteristics when each component is made from a single material, more specifically, when each component is made from a pure iron-based soft magnetic material. In Figure 5, characteristic curve 77 shows the characteristics when each component is made from a single material, more specifically, when each component is made from carbon steel (S10C) for machine structures.

[0092] As is clear from comparing characteristic lines 71, 72, 73, 74, and 75 in Figure 5 with characteristic line 77, if any one of the five components—armament 48, anchor 41, housing 36, yoke 39, and cover 51—is partially made of a different material, the thrust can be increased compared to when all components are made of a single material of the usual metallic material, machine structural carbon steel (S10C). Also, as is clear from comparing characteristic lines 73, 74, and 75 in Figure 5 with characteristic line 76, if any one of the housing 36, yoke 39, and cover 51 is partially made of a different material, the thrust can be increased compared to when all components are made of a single material of pure iron-based soft magnetic material. In this case, for example, comparing characteristic line 76 when made of a single material (pure iron-based soft magnetic material) with characteristic line 74 when the yoke 39 is partially made of a different material, characteristic line 74 shows that thrust can be improved for a stroke of 0.6 to 1.0 mm.

[0093] In contrast, comparing the characteristic curve 76 when the armature 48 is constructed from a single component (pure iron-based soft magnetic material) with the characteristic curve 71 when the armature 48 is partially constructed from a different component, the thrust decreases in the characteristic curve 71 for strokes of 0.6 to 1.0 mm. This is thought to be because partially making the armature 48 from Permendur increases the saturation magnetic flux density, but at the same time decreases the permeability, which affects the thrust waveform on the low stroke side. Furthermore, comparing the characteristic curve 76 when the armature 48 is constructed from a single component (pure iron-based soft magnetic material) with the characteristic curve 73 when the housing 36 is partially constructed from a different component, the thrust can be improved in the characteristic curve 73 for strokes of 0.8 mm. In other words, in this case, the thrust can be greatly increased in the low stroke range.

[0094] Furthermore, comparing the characteristic curve 76 when the cover 51 is constructed from a single component (pure iron-based soft magnetic material) with the characteristic curve 75 when the cover 51 is partially constructed from a different component, the characteristic curve 75 can maintain a thrust waveform almost identical to that of the characteristic curve 74 of the yoke 39, thus improving thrust. On the other hand, comparing the characteristic curve 76 when the cover 51 is constructed from a single component (pure iron-based soft magnetic material) with the characteristic curve 72 when the anchor 41 is partially constructed from a different component, the characteristic curve 72 shows a decrease in thrust in the low stroke range. Specifically, the thrust decreases at a stroke of 0.8 mm. However, in the stroke range of 0.8 to 1.4 mm (at least 0.8 to 1.2 mm), it is possible to obtain a characteristic in which the thrust increases as the stroke increases.

[0095] Next, Figure 6 also shows the relationship between the stroke of the movable element (armature) and the thrust. In this case, Figure 6 shows three examples in which multiple parts (armature 48, housing 36, cover 51) are partially made of separate materials, and two examples in which all are made of a single material. In Figure 6, characteristic line 81 shows the characteristics when the main armature member 62B, the main housing member 62D, and the main cover member 62E are made of carbon steel for machine structures (S10C), and the separate armature member 61B, the separate housing member 61D, and the separate cover member 61E are made of pure iron-based soft magnetic material. In Figure 6, characteristic line 82 shows the characteristics when the main armature member 62B, the main housing member 62D, and the main cover member 62E are made of carbon steel for machine structures (S10C), and the separate armature member 61B, the separate housing member 61D, and the separate cover member 61E are made of Permendur.

[0096] In Figure 6, characteristic curve 83 shows the characteristics when the armature main member 62B, housing main member 62D, and cover main member 62E are made of pure iron-based soft magnetic material, and the armature separate member 61B, housing separate member 61D, and cover separate member 61E are made of Permendur. In Figure 6, characteristic curve 84 shows the characteristics when all parts are made of pure iron-based soft magnetic material. In Figure 6, characteristic curve 85 shows the characteristics when all parts are made of carbon steel for machine structures (S10C). As shown in Figure 6, for example, comparing characteristic curve 84 when made of a single member (pure iron-based soft magnetic material) with characteristic curve 83 when the armature 48, housing 36, and cover 51 are partially made of separate members (Permendur), characteristic curve 83 can improve thrust.

[0097] 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.

[0098] 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).

[0099] When the vehicle is in motion, if vertical vibrations occur due to unevenness in the road surface, the piston rod 8 is displaced so as to extend and 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 current value to the coil 34A of the solenoid 33 is controlled by the controller, and the opening pressure of the pilot valve body 32 is adjusted, thereby variably adjusting the damping force generated by the shock absorber 1.

[0100] 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.

[0101] 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.

[0102] 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.

[0103] 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.

[0104] 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.

[0105] 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.

[0106] In this embodiment, at least one of the armature 48, anchor 41, housing 36, yoke 39, and cover 51 is not made of a single material, but is partially made of different materials 61A, 61B, 61C, 61D, and 61E. Therefore, the magnetic flux concentration area can be made of different materials 61A, 61B, 61C, 61D, and 61E, for example, made of a material with high saturation magnetic flux density and high permeability. This makes it possible to alleviate magnetic saturation and improve thrust. Moreover, since it is possible to use different materials 61A, 61B, 61C, 61D, and 61E that are partially made of different materials, it is also possible to reduce costs compared to changing the material of the entire component.

[0107] According to this embodiment, the outer circumferential protrusion 41C of the anchor 41 is made of a separate component 61A from the anchor main member 62A, which is the part of the anchor 41 other than the outer circumferential protrusion 41C. Therefore, the outer circumferential protrusion 41C, which is the magnetic flux concentration part of the anchor 41, can be made of a separate component 61A made of a material with high saturation magnetic flux density and high permeability. This makes it possible to alleviate magnetic saturation and improve thrust. Moreover, since a separate component 61A made of a different material is used for the outer circumferential protrusion 41C, which is part of the anchor 41, costs can be reduced compared to changing the material of the entire anchor 41.

[0108] According to this embodiment, the groove 48A of the armature 48 is made of a separate member 61B from the main armature member 62B, which is the part of the armature 48 other than the groove 48A. Therefore, the groove 48A, which is the magnetic flux concentration area of ​​the armature 48, can be made of a separate member 61B made of a material with high saturation magnetic flux density and high permeability. This makes it possible to alleviate magnetic saturation and improve thrust. Moreover, since a separate member 61B made of a different material is used for the groove 48A, which is part of the armature 48, costs can be reduced compared to changing the material of the entire armature 48.

[0109] According to the embodiment, the inward flange portion 39D of the yoke 39 is made of a separate member 61C from the main yoke member 62C, which is the part of the yoke 39 other than the inward flange portion 39D. Therefore, the inward flange portion 39D, which is the magnetic flux concentration part of the yoke 39, can be made of a separate member 61C made of a material with high saturation magnetic flux density and high permeability. This makes it possible to alleviate magnetic saturation and improve thrust. Moreover, since a separate member 61C made of a different material is used for the inward flange portion 39D, which is part of the yoke 39, it is possible to reduce costs compared to changing the material of the entire yoke 39.

[0110] According to this embodiment, the cover contact portion 36D of the housing 36 is made of a separate member 61D from the main housing member 62D, which is the part of the housing 36 other than the cover contact portion 36D. Therefore, the cover contact portion 36D, which is the magnetic flux concentration area of ​​the housing 36, can be made of a separate member 61D made of a material with high saturation magnetic flux density and high permeability. This makes it possible to alleviate magnetic saturation and improve thrust. Moreover, since a separate member 61D made of a different material is used for the cover contact portion 36D, which is part of the housing 36, costs can be reduced compared to changing the material of the entire housing 36.

[0111] According to this embodiment, the housing contact portion 51E of the cover 51 is made of a separate member 61E from the main cover member 62E, which is the part of the cover 51 other than the housing contact portion 51E. Therefore, the housing contact portion 51E, which is the magnetic flux concentration area of ​​the cover 51, can be made of a separate member 61E made of a material with high saturation magnetic flux density and high permeability. This makes it possible to alleviate magnetic saturation and improve thrust. Moreover, since a separate member 61E made of a different material is used for the housing contact portion 51E, which is part of the cover 51, it is possible to reduce costs compared to changing the material of the entire cover 51.

[0112] According to the embodiment, the separate members 61A, 61B, 61C, 61D, and 61E are made of a material with higher permeability or higher saturation magnetic flux density than the main members 62A, 62B, 62C, 62D, and 62E. For example, the saturation magnetic flux density of the separate members 61A, 61B, 61C, 61D, and 61E is set to 1.1 times or more that of the main members 62A, 62B, 62C, 62D, and 62E. Also, the permeability of the separate members 61A, 61B, 61C, 61D, and 61E is set to 1.5 times or more that of the main members 62A, 62B, 62C, 62D, and 62E. Therefore, the magnetic flux concentration area can be made of separate members 61A, 61B, 61C, 61D, and 61E with high permeability or high saturation magnetic flux density. This makes it possible to alleviate magnetic saturation and improve thrust.

[0113] In the embodiment, the example described was one in which at least one of the armature 48, anchor 41, housing 36, yoke 39, and cover 51 is not made of a single material, but is partially made of separate components 61A, 61B, 61C, 61D, and 61E. However, the invention is not limited to this, and for example, at least one of the movable element (armature), stator (anchor), housing (storage member), yoke (case member), and cover (cover member) may be made of a single material, and the single material may be a high saturation magnetic flux density material, a high permeability material, or a pure iron-based soft magnetic material. That is, at least one of the armature, anchor, housing, yoke, and cover may be made of a high saturation magnetic flux density material, a high permeability material, or a pure iron-based soft magnetic material that forms the material of the entire component. In this case, magnetic saturation can be mitigated for the entire component, and thrust can be improved.

[0114] Figure 7, like Figures 5 and 6, shows the relationship between the stroke of the movable element (armature) and the thrust. In this case, Figure 7 shows four examples where all parts—armature, anchor, housing, yoke, and cover—are made from a single material. In Figure 7, characteristic line 91 shows the characteristics when all parts (armature, anchor, housing, yoke, and cover) are made from a pure iron-based soft magnetic material that is a high saturation magnetic flux density material (for example, a pure iron-based soft magnetic material that satisfies JIS standard C2504). Characteristic line 92 shows the characteristics when all parts are made from Permendur, which is a high saturation magnetic flux density material. Characteristic line 93 shows the characteristics when all parts are made from Permalloy (for example, 45% Ni), which is a high permeability material. In Figure 7, characteristic line 94 shows the characteristics when all parts are made from carbon steel (S10C), which is a typical metallic material for machine structures.

[0115] As shown in Figure 7, when all components are made of pure iron-based soft magnetic material, Permendur, or Permalloy, the overall thrust increases compared to when all components are made of machine structural carbon steel (S10C). The width of the proportional region is largely influenced by the component shape, so the change due to material change is small. Compared to machine structural carbon steel (S10C), thrust improvements are observed by approximately 35% with Permendur, 15% with pure iron-based soft magnetic material, and approximately 44% with Permalloy. From this, it is considered that permeability contributes more to thrust improvement than saturation magnetic flux density.

[0116] In this embodiment, an intermediate protrusion 41G is provided in the recessed portion 41B of the anchor 41, and a groove 48A is provided in the armature 48 corresponding to this intermediate protrusion 41G. However, the embodiment is not limited to this, and for example, the recessed portion of the anchor may be made into a flat bottom surface, and the opposing portion of the armature (the portion facing the anchor) may also be made flat accordingly.

[0117] In the embodiment, the case in which the housing 36 and the cylinder 44, and the cylinder 44 and the yoke 39 are joined via brazing material was described as an example. However, the embodiment 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.

[0118] In this embodiment, the case in which the anchor 41 is fixed by press-fitting into the fixing hole 39A of the yoke 39 was 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.

[0119] In this embodiment, 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.

[0120] In this embodiment, the example described was one in which one side of the cylinder 44 is fixed to the yoke 39. However, the invention is not limited to this, and for example, one side of the cylinder (jointing member) may be fixed to an anchor.

[0121] In the embodiment, an example was described in which the yoke 39 is provided with the other cylindrical portion 39H, and the tip side (the other side in the axial direction) of the other cylindrical portion 39H is fixed to the outer circumference of the cover 51 by a crimping portion 39J. However, the embodiment 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.

[0122] In this embodiment, the case in which the solenoid 33 is configured as a proportional solenoid was used as an example. However, it is not limited to this, and for example, it may be configured as an ON / OFF type solenoid.

[0123] In this embodiment, 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.

[0124] In this embodiment, the example described was when the solenoid 33 is used as a variable damping force actuator for the shock absorber 1, that is, when the pilot valve body 32, which constitutes the pilot valve of the damping force adjustment valve 18, is the object to be driven by the solenoid 33. 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.

[0125] According to the embodiments described above, at least one of the movable element, stator, housing, yoke, and cover is not made of a single material, but is made of partially different materials. Therefore, the magnetic flux concentration area can be made of a different material, for example, a different material made of a material with high saturation magnetic flux density and high permeability. This makes it possible to alleviate magnetic saturation and improve the thrust of the movable element. Moreover, since partially different materials (different materials) can be used, costs can be reduced compared to changing the material of the entire component.

[0126] According to this embodiment, the cylindrical portion of the stator is made of a separate material from the main stator member, which is the part of the stator other than the cylindrical portion. Therefore, the cylindrical portion, which is the magnetic flux concentration part of the stator, can be made of a separate material with high saturation magnetic flux density and high permeability. This makes it possible to alleviate magnetic saturation and improve the thrust of the movable part. Moreover, since a separate material (different material) is used for the cylindrical portion, which is part of the stator, costs can be reduced compared to changing the material of the entire stator.

[0127] According to this embodiment, the opposing portion of the movable element is made of a separate material from the main movable element, which is the part of the movable element other than the opposing portion. Therefore, the opposing portion, which is the magnetic flux concentration point of the movable element, can be made of a separate material with high saturation magnetic flux density and high permeability. This makes it possible to alleviate magnetic saturation and improve the thrust of the movable element. Moreover, since a separate material (different material) is used for the opposing portion, which is part of the movable element, costs can be reduced compared to changing the material of the entire movable element.

[0128] According to this embodiment, the stator contact portion of the yoke is made of a separate material from the main yoke member, which is the part of the yoke other than the stator contact portion. Therefore, the stator contact portion, which is the magnetic flux concentration area of ​​the yoke, can be made of a separate material with high saturation magnetic flux density and high permeability. This makes it possible to alleviate magnetic saturation and improve the thrust of the movable part. Moreover, since a separate material (different material) is used for the stator contact portion, which is part of the yoke, costs can be reduced compared to changing the material of the entire yoke.

[0129] According to this embodiment, the cover contact portion of the housing is made of a separate material from the main housing component, which is the part of the housing other than the cover contact portion. Therefore, the cover contact portion, which is the magnetic flux concentration area of ​​the housing, can be made of a separate component made of a material with high saturation magnetic flux density and high permeability. This makes it possible to alleviate magnetic saturation and improve the thrust of the movable element. Moreover, since a separate component (different material) is used for the cover contact portion, which is part of the housing, costs can be reduced compared to changing the material of the entire housing.

[0130] According to this embodiment, the housing contact portion of the cover is made of a separate material from the main cover component, which is the part of the cover other than the housing contact portion. Therefore, the housing contact portion, which is the magnetic flux concentration area of ​​the cover, can be made of a separate component made of a material with high saturation magnetic flux density and high permeability. This makes it possible to alleviate magnetic saturation and improve the thrust of the movable element. Moreover, since a separate component (different material) is used for the housing contact portion, which is part of the cover, costs can be reduced compared to changing the material of the entire cover.

[0131] According to the embodiment, the separate component is made of a material with higher magnetic permeability or higher saturation magnetic flux density than the main component, which is the part other than the separate component. Therefore, the magnetic flux concentration area can be made of a separate component with high magnetic permeability or high saturation magnetic flux density. This makes it possible to alleviate magnetic saturation and improve the thrust of the movable element.

[0132] According to the embodiment, at least one of the movable element, stator, housing, yoke, and cover is made of a single material, which is a high saturation magnetic flux density material, a high permeability material, or a pure iron-based soft magnetic material. This allows for the mitigation of magnetic saturation throughout the entire component, thereby improving the thrust of the movable element. [Explanation of Symbols]

[0133] 1 Buffer (damping force adjustable buffer) 2. Outer cylinder 4. Inner cylinder 5 pistons 8 Piston rods 17. Damping force adjustment mechanism 32 Pilot valve body (control valve) 33 Solenoid 34A coil 36 Housing 36D Cover contact area 39 York 39D Inward-facing flange (stator contact area) 41 Anchor (stator) 41C Outer circumference protrusion (tubular part) 48 Amateur 48A Groove section (opposing section) 51 Cover 51E Housing contact area 61A, 61B, 61C, 61D, 61E Separate components 62A, 62B, 62C, 62D, 62E Main components

Claims

1. A coil that is wound in a ring shape and generates a magnetic force when an electric current is passed through it, A movable element made of a magnetic material is provided so as to be movable in the winding axis direction of the coil, A stator provided on one side of the movable element in the direction of movement, A housing in which the movable element is housed, The yoke to which the stator is attached, A magnetic circuit comprising a cover that covers the coil, A solenoid in which at least one of the movable element, the stator, the housing, the yoke, and the cover is not made of a single material but is made of partially different components.

2. The stator has a cylindrical portion into which the movable part enters, The solenoid according to claim 1, wherein the cylindrical portion is made of a separate material from the stator main member, which is a part of the stator other than the cylindrical portion.

3. The movable element has a portion facing the stator, The solenoid according to claim 1, wherein the opposing portion is made of a separate material from the main movable member which is a part of the movable element other than the opposing portion.

4. The yoke has a stator contact portion that contacts the stator, The solenoid according to claim 1, wherein the stator contact portion is made of a separate member from the yoke main member which is a portion of the yoke other than the stator contact portion.

5. The housing has a cover contact portion that contacts the cover, The solenoid according to claim 1, wherein the cover contact portion is made of a separate material from the main housing member which is a part of the housing other than the cover contact portion.

6. The cover has a housing contact portion that contacts the housing, The solenoid according to claim 1, wherein the housing contact portion is made of a separate material from the main cover member which is a part of the cover other than the housing contact portion.

7. The solenoid according to claim 1, wherein the separate member is made of a material having higher magnetic permeability or higher saturation magnetic flux density than the main member which is a part other than the separate member.

8. A coil that is wound in a ring shape and generates a magnetic force when an electric current is passed through it, A movable element made of a magnetic material is provided so as to be movable in the winding axis direction of the coil, A stator provided on one side of the movable element in the direction of movement, A housing in which the movable element is housed, The yoke to which the stator is attached, A magnetic circuit comprising a cover that covers the coil, A solenoid in which at least one of the movable element, the stator, the housing, the yoke, and the cover is made of a single material, the single material being a high saturation magnetic flux density material, a high permeability material, or a pure iron-based soft magnetic material.

9. A damping force adjustment mechanism, wherein the damping force adjustment mechanism is A coil that is wound in a ring shape and generates a magnetic force when an electric current is passed through it, A movable element made of a magnetic material is provided so as to be movable in the winding axis direction of the coil, A stator provided on one side of the movable element in the direction of movement, A housing in which the movable element is housed, The yoke to which the stator is attached, A magnetic circuit is formed, and a cover covers the coil, The system comprises a control valve controlled by the axial movement of the movable element, A damping force adjustment mechanism in which at least one of the movable element, the stator, the housing, the yoke, and the cover is not made of a single material but is made of partially separate components.

10. 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 is wound in a ring shape and generates a magnetic force when an electric current is passed through it, A movable element made of a magnetic material is provided so as to be movable in the winding axis direction of the coil, A stator provided on one side of the movable element in the direction of movement, A housing in which the movable element is housed, The yoke to which the stator is attached, A magnetic circuit comprising a cover that covers the coil, A damping force adjustable shock absorber in which at least one of the movable element, the stator, the housing, the yoke, and the cover is not made of a single material but is made of partially different components.

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