Solenoid valve and damper

Abstract

A solenoid valve (V) has: a valve seat member (13); a ring-shaped first spool (14) that can be seated off to open and closed a port (13c) with respect to a ring-shaped valve seat (13d); a second spool (15) that can be axially moved with respect to the valve seat member (13) and the first spool (14) and can be seated off to open and closed the port (13c) with respect to the first spool (14); and a solenoid (S) that can apply a thrust to the second spool (15) to push press toward the valve seat member side; the first spool (14) and the second spool (15) are applied a force toward a direction away from the valve seat member (13) due to a pressure on one side of the port (13c), are applied a force toward a direction to separate from each other due to a pressure on the other side of the port (13c), and an area of a front side pressure receiving portion of the second spool (15) is larger than an area of a back side pressure receiving portion.

Description

Technical Field

[0001] This invention relates to a solenoid valve and a damper. Background Technology

[0002] Solenoid valves are used as variable damping valves for shock absorbers installed between the vehicle body and wheels. They adjust the damping force generated by the shock absorber in a way that is suitable for suppressing vehicle body vibration, thereby improving the ride comfort of the vehicle.

[0003] For example, as disclosed in JP2019-160994A, this solenoid valve, located in the piston portion of a buffer, includes: a main channel connecting the elongation-side chamber and the compression-side chamber; an annular valve seat component through which the main channel passes; a main valve body, seated relative to the valve seat component, applying resistance to the flow of liquid through the main channel; an elongation-side pressure inlet channel with a throttling section in the middle, reducing the pressure in the elongation-side chamber and introducing it into the back pressure chamber on the back of the main valve body; and a compression-side pressure inlet channel, introducing the compression-side pressure... The pressure in the chamber is reduced and introduced into the back pressure chamber; a control valve controls the pressure in the back pressure chamber; and a solenoid applies thrust to the control valve; the main valve body has an annular first valve core that is seated relative to the valve seat component, and a second valve core stacked on the opposite side of the valve seat component of the first valve core and seated relative to the first valve core, the first valve core and the second valve core are subjected to a force in the direction away from the valve seat component due to the pressure in the extended side chamber, and the second valve core is subjected to a force in the direction away from the first valve core due to the pressure on the inner circumferential side of the first valve core.

[0004] Furthermore, in this solenoid valve configuration, when hydraulic oil moves from the extension side chamber to the compression side chamber, the pressure in the extension side chamber causes the first and second valve cores to move away from the valve seat assembly together, opening the valve. However, by adjusting the pressure in the back pressure chamber according to the amount of current applied to the solenoid, the opening pressure can be adjusted, thus changing the damping force. Additionally, in the solenoid valve, when hydraulic oil moves from the compression side chamber to the extension side chamber, the pressure in the compression side chamber causes the first and second valve cores to separate, opening the main passage. However, by adjusting the thrust pushing the second valve core according to the amount of current applied to the solenoid, the opening pressure can be adjusted, thus changing the damping force.

[0005] Existing technical documents Patent documents Patent Document 1: JP2019-160994A Summary of the Invention The problem the invention aims to solve In this solenoid valve, when hydraulic oil flows from the compression side chamber to the extension side chamber in the main channel, the first valve core is pushed towards the valve seat component by the pressure of the compression side chamber, while the second valve core is pushed away from the valve seat component by the pressure of the compression side chamber.

[0006] Therefore, when the force pushing the second valve core away from the valve seat component exceeds the resultant force of the solenoid and the force pushing the second valve core towards the valve seat component, the solenoid valve opens and the main channel is opened.

[0007] However, in conventional solenoid valves, the seat diameter of the seat portion where the second valve core abuts against the first valve core is small, and the pressure area on the front side of the compression chamber, which acts to push the second valve core away from the valve seat component, is much smaller than the pressure area on the back side of the compression chamber, which acts to push the second valve core closer to the valve seat component.

[0008] Therefore, when hydraulic oil flows from the compression side chamber to the extension side chamber in the main channel, the force pushing the second valve core against the first valve core becomes excessive, making it difficult for the second valve core to separate from the first valve core. Consequently, in conventional solenoid valves, even when the solenoid thrust is reduced to an extremely low level to generate soft damping force, the damping force may still become large, thus affecting vehicle ride comfort.

[0009] The purpose of this invention is to provide a solenoid valve and damper that can reduce the damping force generated in soft mode and improve the ride comfort of the vehicle.

[0010] Problem-solving methods To solve the aforementioned problem, the solenoid valve of the present invention is characterized by comprising: a valve seat component having an annular valve seat surrounding a flow path; an annular first valve core axially movable relative to the valve seat component and capable of opening and closing the flow path relative to the annular valve seat; a second valve core axially movable relative to the valve seat component and the first valve core, stacked on the opposite side of the valve seat component of the first valve core, and capable of opening and closing the flow path relative to the first valve core; and a solenoid that can apply a pushing force to the second valve core towards the valve seat component; the first valve core and the second valve core, due to flow... The pressure on one side of the flow path is applied together with a force in the direction away from the valve seat component, and a force in the direction of separation is applied due to the pressure on the other side of the flow path. The second valve core has: a front-side pressure-bearing portion, which acts as a force away from the valve seat component due to the pressure in the flow path facing the valve seat component; a back-side pressure-bearing portion, which acts as a force in the direction of approaching the valve seat component due to the pressure acting on the opposite side facing the valve seat component; and a channel that guides the pressure in the flow path to the back-side pressure-bearing portion; the area of ​​the front-side pressure-bearing portion is larger than the area of ​​the back-side pressure-bearing portion.

[0011] In the solenoid valve constructed in this way, the area of ​​the front pressure-bearing part in the second valve core is larger than the area of ​​the back pressure-bearing part. Therefore, during the contraction action, the pressure acting on the second valve core in the flow path applies a force to the second valve core in a direction away from the first valve core. Thus, if the thrust of the solenoid is reduced and the opening pressure of the solenoid valve is reduced, the damping force generated in the soft mode can be reduced, thereby improving the ride comfort of the vehicle. Attached Figure Description

[0012] Figure 1 This is a longitudinal cross-sectional view of a buffer for a solenoid valve with one embodiment.

[0013] Figure 2 This is an enlarged longitudinal cross-sectional view of the piston portion of a buffer of a solenoid valve having one embodiment.

[0014] Figure 3 This is an enlarged cross-sectional view of a solenoid valve according to one embodiment.

[0015] Figure 4 This is a characteristic diagram showing the relationship between the supply current and thrust of the solenoid in a solenoid valve according to one embodiment.

[0016] Figure 5 This is a diagram showing the damping force characteristics of a buffer of a solenoid valve having one embodiment. Detailed Implementation

[0017] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Figure 1 As shown, in one embodiment of the present invention, the buffer D is constructed comprising the following components: a cylinder 1 serving as a housing; a piston rod 2 axially movable and inserted into the cylinder 1; a piston 3 connected to the piston rod 2 and axially movable and inserted into the cylinder 1; and a solenoid valve V housed within the cylinder 1, positioned between two chambers, an extension chamber R1 and a compression chamber R2, located within the cylinder 1. Furthermore, in the case of buffer D, it is used between the body and wheels of a vehicle (not shown) to suppress vibrations of the body and wheels.

[0018] The following will describe in detail the various parts of buffer D. For example... Figure 1 As shown, the buffer D includes a bottomed cylindrical cylinder 1 as an outer tube, a piston rod 2 movably inserted into the cylinder 1, and a piston 3 connected to the piston rod 2 and movably inserted into the cylinder 1, dividing the cylinder 1 into an elongated side chamber R1 and a compression side chamber R2 as a working chamber.

[0019] Moreover, in piston rod 2 Figure 1A bracket (not shown) is provided at the upper middle end, i.e., the base end, and the piston rod 2 is connected to the vehicle body (not shown) via the bracket. In addition, a bracket (not shown) is also provided at the bottom 1a of the cylinder 1, and the cylinder 1 is connected to the wheel (not shown) of the vehicle via the bracket.

[0020] Thus, the buffer D is installed between the vehicle body and the wheels. Moreover, when the vehicle is traveling on uneven roads or other surfaces that cause the wheels to vibrate up and down relative to the vehicle body, the piston rod 2 moves in and out of the cylinder 1 to extend and retract the buffer D, and the piston 3 moves up and down (axially) within the cylinder 1.

[0021] Furthermore, the buffer D has an annular guide 10 that blocks the upper end of the cylinder 1 and allows the piston rod 2 to slide freely through its inner circumference. Therefore, the cylinder 1 is a sealed space. Moreover, from the perspective of the piston 3 inside the cylinder 1, the free piston 11 slides freely into the cylinder on the side opposite to the piston rod 2.

[0022] A liquid chamber L is formed on the upper side of the free piston 11 inside the cylinder 1, and a gas chamber G is formed on the lower side. Furthermore, the liquid chamber L is divided by the piston 3 into an extension-side chamber R1 on the piston rod 2 side and a compression-side chamber R2 on the piston 3 side, both filled with liquid. Additionally, the liquid filled in the buffer D can be hydraulic oil, water, an aqueous solution, or other liquids. On the other hand, the gas chamber G is sealed with air or nitrogen in a compressed state.

[0023] Furthermore, during the extension of the buffer D, the piston rod 2 retracts from the cylinder 1. As the volume of the retracted piston rod 2 increases within the cylinder, the free piston 11 moves upward within the cylinder 1, causing the gas chamber G to expand. Conversely, during the contraction of the buffer D, the piston rod 2 retracts into the cylinder 1. As the volume of the retracted piston rod 2 decreases within the cylinder, the free piston 11 moves downward within the cylinder 1, causing the gas chamber G to contract.

[0024] Alternatively, an air bladder or bellows can be used instead of the free piston 11 to separate the liquid chamber L and the gas chamber G. The configuration of this movable partition wall as a separator can be appropriately modified.

[0025] Furthermore, in this embodiment, the buffer D is a single-rod, single-rod type buffer. When the buffer D extends or retracts, the free piston 11 expands or contracts the gas chamber G to compensate for the volume of the piston rod 2 entering and exiting the cylinder 1. However, the configuration used for this volume compensation can also be appropriately modified.

[0026] For example, when the free piston 11 and gas chamber G are eliminated, and an outer tube is installed around the outer periphery of the cylinder 1, forming a liquid storage chamber between the cylinder 1 and the outer tube, making the buffer a multi-cylinder type buffer, the volume compensation of the piston rod 2 entering and exiting the cylinder 1 can also be achieved through the liquid storage chamber. Alternatively, the liquid storage chamber can also be formed in a liquid storage tank that is separate from the cylinder 1. Furthermore, the buffer D can also be configured as a double-rod type buffer with a piston 3 installed in the center of the piston rod 2, and the ends of the piston rod 2 protruding outward from both ends of the cylinder 1.

[0027] like Figure 2 As shown, the piston rod 2 is cylindrical, comprising a rod body 2a protruding from the inside of the guide member 10 to the outside of the cylinder 1 at its upper end, and a topped cylindrical outer shell 2b connected to the lower end of the rod body 2a and internally housing the solenoid valve V's solenoid S. The outer shell 2b is formed of a soft magnetic material, such as... Figure 2 As shown, it has a top 2b1 that is annular and whose inner periphery is connected to the lower end of the rod body 2a, and a cylindrical portion 2b2 that hangs down from the outer periphery of the top 2b1.

[0028] Furthermore, a valve core support 12 is threaded onto the inner circumference of the cylindrical portion 2b2 of the piston rod 2, thereby connecting the piston 3 to the valve core support 12. Moreover, the valve core support 12 houses all the components constituting the solenoid valve V, except for the solenoid S.

[0029] like Figure 2 As shown, the solenoid valve V includes a valve seat component 13, a first valve core 14, a second valve core 15, and a solenoid S. As previously described, the solenoid S is housed within the housing 2b at the lower end of the piston rod 2, and the valve seat component 13, the first valve core 14, and the second valve core 15 are housed within the valve core support 12.

[0030] like Figure 3 As shown, the valve core support 12 is cylindrical, and its upper end is threaded to the inner circumference of the cylindrical portion 2b2 of the piston rod 2 to connect it to the piston rod 2. Specifically, the inner diameter of the valve core support 12 gradually increases from the upper end. The inner circumference of the valve core support 12 includes an uppermost small inner diameter portion 12a, a middle inner diameter portion 12b connected to the lower part of the small inner diameter portion 12a and having an inner diameter larger than that of the small inner diameter portion 12a, a large inner diameter portion 12c connected to the lower part of the middle inner diameter portion 12b and having an inner diameter larger than that of the middle inner diameter portion 12b, and a protrusion 12d protruding axially towards the inner circumference from the middle of the large inner diameter portion 12c. A threaded portion 12e is formed below the protrusion 12d of the large inner diameter portion 12c of the valve core support 12.

[0031] Furthermore, the outer diameter of the valve core support 12 is the largest at the central portion. Around the outer periphery of the valve core support 12, there is a fitting portion 12f with a smaller outer diameter at the top, which inserts into the cylindrical portion 2b2 of the outer casing 2b and is threadedly engaged; a large outer diameter portion 12g connected to the lower part of the fitting portion 12f and having the largest outer diameter; and a piston fitting portion 12h connected to the lower part of the large outer diameter portion 12g and having a smaller outer diameter than the large outer diameter portion 12g, which fits into the piston 3. Furthermore, the valve core support 12 includes: a pilot channel 12i, which opens from the lower outer periphery of the fitting portion 12f and leads to the middle inner diameter portion 12b; and a connecting hole 12j, which opens from the outer periphery of the large outer diameter portion 12g and leads to the upper part of the protrusion 12d of the large inner diameter portion 12c. Additionally, the pilot channel 12i includes a throttling portion O1 that functions as a throttling orifice to resist the flow of liquid passing through the pilot channel 12i.

[0032] like Figure 3 As shown, the valve seat component 13 is annular and fits below the protrusion 12d of the large inner diameter portion 12c. Specifically, the valve seat component 13 includes: a fitting cylindrical portion 13a, which fits into the inner periphery of the protrusion 12d of the valve core support 12; and a flange 13b, which protrudes radially from the lower outer periphery of the fitting cylindrical portion 13a and abuts against the protrusion 12d. Figure 2 The lower end; port 13c, formed by the gap inside the fitting cylinder portion 13a; annular valve seat 13d, which protrudes axially from the upper end of the fitting cylinder portion 13a and surrounds the port 13c; step portion 13e, which is formed by making the inner diameter of the lower side of the fitting cylinder portion 13a larger than that of the upper side; and threaded portion 13f, which is formed on the inner circumference of the fitting cylinder portion 13a and is located further down than the step portion 13e.

[0033] The valve seat component 13 constructed in this manner is fixed inside the valve core support 12 by fitting the fitting sleeve portion 13a into the protrusion 12d of the large inner diameter portion 12c of the valve core support 12, and by threading the piston support 17 into the threaded portion 12e on the lower side of the large inner diameter portion 12c of the valve core support 12 while the flange 13b abuts against the lower end of the protrusion 12d.

[0034] Furthermore, a guide member 16 for guiding the first valve core 14 is threadedly engaged in a threaded portion 13f located on the inner periphery of the fitting cylindrical portion 13a of the valve seat component 13, further below the step portion 13e. The guide member 16 includes: a fixed portion 16a, which is annular and inserted into the lower end of the fitting cylindrical portion 13a, and whose outer periphery is threadedly engaged with the threaded portion 13f of the valve seat component 13; a guide cylinder 16b, which stands upright from the inner periphery of the fixed portion 16a, leaving an annular gap, and is inserted into the inner periphery of the fitting cylindrical portion 13a of the valve seat component 13; and a plurality of holes 16c, which radially penetrate the guide cylinder 16b to connect the inside and outside of the guide cylinder 16b.

[0035] like Figure 3As shown, when the guide member 16 threads the fixing part 16a with the threaded part 13f of the valve seat member 13, it is fixed to the valve seat member 13 and the upper end of the hole 16c of the guide cylinder 16b protrudes further upward toward the annular valve seat 13d. Alternatively, the guide member 16 can be integrated with the valve seat member 13, and together with the valve seat member 13, it can be constituted as a single part.

[0036] like Figure 3 As shown, the piston support 17 includes: a disc portion 17a, which is disc-shaped and threadedly engaged with a threaded portion 12e on the lower inner circumference of the valve core support 12; a piston retaining shaft 17b, which extends axially downward from the lower end of the axial center portion of the disc portion 17a and forms a threaded portion on the outer circumference of the front end; and a hole 17c, which axially penetrates the disc portion 17a and communicates with the inner space of the guide member 16. As described above, when the piston support 17 is fixed by threaded engagement with the lower inner circumference of the large inner diameter portion 12c of the valve core support 12, the valve seat member 13 and the guide member 16 fixed to the valve seat member 13 are cooperatively fixed with the protrusion 12d of the valve core support 12.

[0037] On the outer periphery of the piston retaining shaft 17b in the piston bracket 17, an extension-side soft valve 18 and a compression-side soft valve 19 are installed together with the piston 3. Specifically, the piston 3, the extension-side soft valve 18, and the compression-side soft valve 19 are annular and are fitted into the outer periphery of the piston retaining shaft 17b. They are then fixed to the piston retaining shaft 17b by a piston nut 23 that is threaded to the front end of the piston retaining shaft 17b.

[0038] The piston 3 includes: an annular body portion 3a, which is fitted to the outer periphery of the piston retaining shaft 17b; a cylindrical portion 3b, which is provided on the outer periphery of the body portion 3a and is fitted with a piston ring 3c that slides in contact with the inner periphery of the cylinder 1; and an extension side passage 3e and a compression side passage 3d, which axially penetrate the body portion 3a.

[0039] When piston 3 is mounted on piston support 17, the inner circumference of cylinder 3b is fitted into the lower outer circumference of valve core support 12, and the piston ring 3c mounted on the outer circumference of cylinder 3b slides into contact with the inner circumference of cylinder 1, dividing the cylinder 1 into... Figure 1 The upper side has an elongated side chamber R1, and the lower side has a compression side chamber R2. In addition, a sealing ring 12k installed on the outer periphery of the valve core support 12 and the outer periphery of the piston fitting part 12h and the cylinder part 3b of the piston 3 is used to seal the space between them, preventing liquid from bypassing the solenoid valve V and flowing back and forth between the elongated side chamber R1 and the compression side chamber R2.

[0040] Furthermore, the extension-side passage 3e and compression-side passage 3d of the piston 3 connect the compression-side chamber R2 with the space between the valve core support 12 and the piston 3 and piston support 17. The valve core support 12 is connected to the extension-side chamber R1 via a connecting hole 12j that opens from the large outer diameter portion 12g to the large inner diameter portion 12c. Additionally, the port 13c formed on the inner side of the valve seat component 13 is connected to the space between the piston 3 and piston support 17 via the hole 16c, the guide component 16, and the hole 17c, and is also open within the valve core support 12. The flow path F in the solenoid valve V is formed by the connecting hole 12j, the valve core support 12, the port 13c, the hole 16c, and the guide component 16. The extension-side chamber R1 and the compression-side chamber R2 are connected via the flow path F, the hole 17c, the extension-side passage 3e, and the compression-side passage 3d.

[0041] The extension-side soft valve 18 is an annular vane valve stacked below the main body 3a of the piston 3. Its inner circumference is fixed to the outer circumference of the piston retaining shaft 17b together with the piston 3, allowing the outer circumference to bend to open and close the extension-side passage 3e. For the flow of liquid from the extension-side chamber R1 to the compression-side chamber R2 in the extension-side passage 3e, the extension-side soft valve 18 bends its outer circumference to allow the flow and to resist the flow. Conversely, for the flow of liquid from the compression-side chamber R2 to the extension-side chamber R1 in the extension-side passage 3e, it closes the lower end of the extension-side passage 3e to prevent the flow.

[0042] The compression-side soft valve 19 is an annular vane valve stacked above the main body 3a of the piston 3. Its inner circumference is fixed to the outer circumference of the piston retaining shaft 17b together with the piston 3, allowing the outer circumference to bend to open and close the compression-side passage 3d. For the flow of liquid from the compression-side chamber R2 to the extension-side chamber R1 in the compression-side passage 3d, the compression-side soft valve 19 bends its outer circumference to allow the flow and applies resistance to the flow. Conversely, for the flow of liquid from the extension-side chamber R1 to the compression-side chamber R2 in the compression-side passage 3d, it closes the upper end of the compression-side passage 3d to prevent the flow.

[0043] The first valve core 14 is annular, extending along the axial direction. Figure 3 The guide cylinder 16b is movably mounted on the guide component 16 in the vertical direction. Figure 3The outer periphery of the upper middle part is axially aligned with the annular valve seat 13d of the valve seat component 13. The outer diameter of the first valve core 14 is larger than the outer diameter of the annular valve seat 13d, and the inner diameter of the first valve core 14 is smaller than the inner diameter of the annular valve seat 13d. The inner periphery of the first valve core 14 slides in contact with the outer periphery of the guide cylinder 16b, and can axially approach or move away from the valve seat component 13, and can be seated relative to the annular valve seat 13d. The first valve core 14 slides in contact with the outer periphery of the guide cylinder 16b of the guide component 16 fixed to the valve seat component 13, and is therefore positioned radially, and can be seated relative to the annular valve seat 13d in the valve seat component 13 without axial swinging.

[0044] In addition, a hole 16c is provided on the guide cylinder 16b closer to the valve seat component than the first valve core 14. Even when the lower end of the first valve core 14 is seated on the upper end of the annular valve seat 13d, the space on the outer periphery of the guide cylinder 16b and the space on the valve seat component side of the first valve core 14, that is, the space between the fitting cylinder portion 13a of the valve seat component 13 and the guide cylinder 16b, is connected to the inside of the guide cylinder 16b.

[0045] like Figure 3 As shown, the second valve core 15 includes: a cylindrical main body portion 15a; an annular flange portion 15b, disposed on the outer periphery of the main body portion 15a and protruding radially outward; an annular protrusion 15c, protruding from the lower end of the valve seat component of the flange portion 15b; a valve hole 15d, opening axially downward from the axial center portion of the upper end of the valve seat component of the main body portion 15a; a control valve seat 15e, surrounding the upper end of the main body portion 15a and the area around the valve hole 15d; a main body passage 15f, opening from the lower end of the main body portion 15a, arranged linearly along the axial direction and leading to the upper end of the main body portion 15a; a flange passage 15g, opening from the lower end of the flange portion 15b and the inner side of the annular protrusion 15c, arranged linearly along the axial direction and leading to the upper end of the flange portion 15b; and a pressure control passage 15h, opening from the side of the main body portion 15a and leading into the valve hole 15d.

[0046] Furthermore, the second valve core 15 makes the outer periphery of the main body portion 15a slide in contact with the small inner diameter portion 12a of the inner periphery of the valve core support 12, and makes the outer periphery of the flange portion 15b slide in contact with the middle inner diameter portion 12b of the inner periphery of the valve core support 12, and is movably inserted into the inner periphery of the valve core support 12 along the axial direction, i.e., the up and down direction.

[0047] When the second valve core 15 is inserted into the valve core support 12, a back pressure chamber P is formed between it and the valve core support 12. This back pressure chamber P is divided by the back side end of the valve seat opposite to the flange portion 15b, the outer periphery of the main body portion 15a, the middle inner diameter portion 12b of the valve core support 12, and the stepped boundary between the middle inner diameter portion 12b and the small inner diameter portion 12a. The back pressure chamber P is connected to the elongated side chamber R1 through the pilot channel 12i that radially penetrates the valve core support 12. In addition, it is connected to the valve hole 15d through the pressure control channel 15h provided in the second valve core 15, and to the flow path F through the flange portion channel 15g.

[0048] Furthermore, the main body channel 15f opens from the lower end of the main body 15a, is linearly arranged parallel to the axis of the second valve core 15, and leads to the upper end of the main body 15a. Additionally, the flange channel 15g is the lower end of the flange 15b, opens from the inside of the annular protrusion 15c, is linearly arranged parallel to the axis of the second valve core 15, and leads to the upper end of the flange 15b.

[0049] Furthermore, the annular protrusion 15i rises from the outer periphery of the end on the back side opposite to the valve seat component of the main body portion 15a of the second valve core 15, ensuring the engagement length of the second valve core 15 relative to the small inner diameter portion 12a of the valve core support 12, thereby enabling the second valve core 15 to stably move relative to the valve core support 12 along... Figure 3 The vertical direction refers to axial movement.

[0050] Furthermore, a check valve 20 for opening and closing the flange passage 15g is installed on the outer periphery of the main body 15a of the second valve core 15. The check valve 20 includes: an annular valve body 20a, which is stacked on the opposite side of the valve seat component of the flange 15b of the second valve core 15, i.e., the back side end, and is slidably mounted on the outer periphery of the main body 15a; an annular spring seat 20b, which is disposed on the opposite side of the flange of the valve body 20a, fixed to the outer periphery of the main body 15a and facing the valve body 20a axially; and a wave washer 20c, which serves as a spring, is installed between the valve body 20a and the spring seat 20b.

[0051] Wave washer 20c pulls valve body 20a toward flange 15b. Figure 3The upper middle part, i.e., the back side, applies force. Furthermore, the valve body 20a, guided by the main body 15a, can move axially. When it abuts against the flange portion 15b, it closes the flange passage 15g; when it moves away from the flange portion 15b, it opens the flange passage 15g. Therefore, for the flow of liquid in the flange passage 15g from the valve seat member side towards the back pressure chamber P, the valve body 20a retracts from the flange portion 15b to open the flange passage 15g, allowing liquid flow. Conversely, for the flow of liquid in the flange passage 15g from the back pressure chamber P towards the valve seat member side, the valve body 20a abuts against the flange portion 15b to close the flange passage 15g, preventing liquid flow. Therefore, the flange passage 15g is configured as a one-way passage that only allows the flow of liquid from the valve seat member side towards the back pressure chamber P. In addition, the spring in the check valve 20 only needs to be able to apply force to the valve body 20a to close the valve, so it can also be an elastic body other than the wave washer 20c.

[0052] The annular protrusion 15c includes: an annular base 15c1, extending from the flange portion 15b. Figure 3 The lower end of the valve core 15b protrudes downward along the axial direction and its outer diameter is enlarged to be larger than that of the flange portion 15b; and the annular protrusion 15c2 protrudes downward from the outer periphery of the lower end of the base 15c1, and its lower end has a flat surface that can abut against the opposite side, i.e. the back side, of the valve seat of the first valve core 14.

[0053] After the first valve core 14 and the second valve core 15, constructed as described above, are inserted into the valve core bracket 12, and the valve seat component 13 and the guide component 16 are fixed to the valve core bracket 12 using the piston bracket 17, the first valve core 14 is axially movable and mounted on the outer periphery of the guide component 16, and can move axially relative to the valve seat component 13 and the valve core bracket 12. Figure 3 The second valve core 15 moves vertically and can be seated relative to the valve seat component 13. The second valve core 15 slides in contact with the inner circumference of the valve core support 12, forming a back pressure chamber P between itself and the valve core support 12. Guided by the valve core support 12, it can move axially (vertically and axially) relative to the valve core support 12 and the valve seat component 13, and the lower end face of the annular protrusion 15c can be seated relative to the back surface of the first valve core 14. Furthermore, even if the pressure acting on the first valve core 14 shifts due to uneven flow of liquid attempting to pass through the solenoid valve V around the first valve core 14, causing a lateral force that causes it to move radially, it will not axially oscillate due to the support of the guide component 16. Therefore, the lateral force acting on the first valve core 14 will not press the second valve core 15 against the valve core support 12, thus preventing increased sliding resistance and difficulty in axial movement.

[0054] When the first valve core 14 moves away from the annular valve seat 13d of the valve seat component 13, the port 13c of the valve seat component 13 connects with the connecting hole 12j in the valve core support 12, opening the flow path F and thus connecting the extension side chamber R1 and the compression side chamber R2. With the first valve core 14 seated on the annular valve seat 13d, when the second valve core 15 moves away from the first valve core 14, the port 13c of the valve seat component 13 connects with the connecting hole 12j in the valve core support 12, opening the flow path F and thus connecting the extension side chamber R1 and the compression side chamber R2.

[0055] Furthermore, when the first valve core 14 is seated on the annular valve seat 13d of the valve seat component 13, and the second valve core 15 is seated on the first valve core 14, the solenoid valve V closes, thus sealing the flow path F. A throttling orifice (not shown) is provided on the annular valve seat 13d or the annular protrusion 15c. When the solenoid valve V is closed, the port 13c of the valve seat component 13 and the connecting hole 12j in the valve core support 12 are connected only through the throttling orifice.

[0056] Thus, when the first valve core 14 leaves the annular valve seat 13d, or when the first valve core 14 is seated on the annular valve seat 13d and the second valve core 15 leaves the first valve core 14, the solenoid valve V opens, connecting the extension side chamber R1 and the compression side chamber R2 via the flow path F. On the other hand, when the first valve core 14 is seated on the annular valve seat 13d and the second valve core 15 is seated on the first valve core 14, the solenoid valve V closes the flow path F, but only prevents the connection between the extension side chamber R1 and the compression side chamber R2 through the throttling orifice.

[0057] Here, when the buffer D extends, and the liquid attempts to move in the flow path F along the direction from the extended side chamber R1, which is one side of the flow path F, toward the compression side chamber R2, which is the other side, the pressure of the extended side chamber R1 acts on the side of the valve seat component of the first valve core 14, i.e., the front side. Figure 3 The portion that is further outward from the annular valve seat 13d than the portion that abuts against it. Therefore, when the diameter of the first valve core 14 is set to φa, and the outer diameter of the upper end face of the annular valve seat 13d that abuts against the first valve core 14 is set to φb, the first valve core 14 is pushed towards... Figure 3 The magnitude of the force on the upper middle part, i.e., the opposite side of the valve seat component, is the area of ​​the circle with diameter φa minus the area of ​​the circle with diameter φb, and then the obtained area is multiplied by the pressure of the elongated side chamber R1.

[0058] On the other hand, the pressure of the elongated side chamber R1 acts on the opposite side, i.e., the back side, of the valve seat component of the first valve core 14. Figure 3 The upper middle part), and the opposite side, i.e. the back side, of the valve seat component of the annular protrusion 15c of the second valve core 15 (the upper middle part), and the back side. Figure 3 (Above). Therefore, when the diameter of the flange portion 15b is set to φc, the first valve core 14 and the second valve core 15 are pushed towards... Figure 3The magnitude of the force on the lower middle side, i.e., the valve seat component side, is the area of ​​the circle with diameter φa minus the area of ​​the circle with diameter φc, and then the obtained area is multiplied by the pressure of the elongation side chamber R1. In addition, the pressure of the elongation side chamber R1 also acts on the back of the annular protrusion 15c of the second valve core 15. Therefore, the second valve core 15 is pushed against the first valve core 14 due to the pressure of the elongation side chamber R1. Thus, when the buffer D attempts to elongate during the movement of the fluid in the elongation side chamber R1 to the compression side chamber R2, the first valve core 14 remains in contact with the annular protrusion 15c and does not separate.

[0059] In the above description, when the buffer D extends as the liquid attempts to flow from the extension chamber R1 to the compression chamber R2, the force pushing up the first valve core 14 is the area of ​​the circle with diameter φc minus the area of ​​the circle with diameter φb, multiplied by the pressure in the extension chamber R1. Here, the outer diameter φc of the flange 15b is larger than the outer diameter φb of the annular valve seat 13d. Therefore, when the buffer D extends as the liquid attempts to flow from the extension chamber R1 to the compression chamber R2, the force equal to the area obtained by subtracting the area of ​​the circle with diameter φb from the area of ​​the circle with diameter φc, multiplied by the pressure in the extension chamber R1, acts in the direction that causes both the first valve core 14 and the second valve core 15 to leave the valve seat component 13.

[0060] Furthermore, the elongated side chamber R1 connects to the back pressure chamber P via the pilot channel 12i of the valve core support 12. Therefore, the second valve core 15 exerts force on the valve seat component 13 due to the pressure of the back pressure chamber P. When the diameter of the main body 15a of the second valve core 15 is set to φd, the magnitude of the force that presses down on the second valve core 15 under the pressure of the back pressure chamber P is the value obtained by multiplying the area of ​​the circle with diameter φc by the area of ​​the circle with diameter φd, and then multiplying it by the pressure of the back pressure chamber P.

[0061] The pressure in the back pressure chamber P is adjusted by the control valve 21 described below. Therefore, when the buffer D extends as the liquid attempts to flow from the extension side chamber R1 to the compression side chamber R2, if the force pushing up the first valve core 14 due to the pressure in the extension side chamber R1 exceeds the resultant force of the force pressing down the first valve core 14 and the second valve core 15 due to the pressure in the extension side chamber R1 and the force pressing down the second valve core 15 due to the pressure in the back pressure chamber P, the first valve core 14 and the second valve core 15 move away from the valve seat component 13, and the solenoid valve V opens. Thus, in the solenoid valve V of this embodiment, the opening pressure can be adjusted by adjusting the pressure in the back pressure chamber P during the extension operation of the buffer D.

[0062] Next, when the buffer D contracts and the liquid attempts to move in the flow path F from the compression side chamber R2 toward the extension side chamber R1, the pressure in the port 13c of the valve seat component 13 acts on the side, i.e., the front, of the valve seat component of the first valve core 14 via the hole 16c of the guide component 16. Figure 3 The portion located below the annular valve seat 13d and further inward on the inner circumference than the portion abutting against it. On the other hand, the pressure within the port 13c of the valve seat component 13 also originates from the opposite side of the valve seat of the first valve core 14, i.e., the back side (…). Figure 3 (Above) and the portion of the annular protrusion 15c2 that abuts against the flat surface of the first valve core 14, acting on the inner circumferential side. Here, the inner diameter of the portion of the annular valve seat 13d that abuts against the first valve core 14 is smaller than the inner diameter of the portion of the protrusion 15c2 that abuts against the flat surface of the first valve core 14. Therefore, the area of ​​pressure acting on the back side of the first valve core 14 within the port 13c is greater than the area acting on the front side of the first valve core 14. The first valve core 14 is pushed against the valve seat component 13 without moving away from the annular valve seat 13d.

[0063] On the other hand, even when the solenoid valve V is in the closed state, the flow path F is still connected to the valve core support 12, so the pressure in the flow path F also acts on the second valve core 15.

[0064] In detail, the pressure within the flow path F originates from the side, i.e., the front, of the valve seat component of the main body 15a and flange 15b of the second valve core 15. Figure 3 The portion of the second valve core 15 (located on the lower side) with an annular protrusion 15c abutting against the first valve core 14, with its inner circumferential portion acting as a front-side pressure-bearing portion, applies force to the second valve core 15 on the opposite side of the valve seat component. Therefore, when the inner diameter of the protrusion 15c2 of the second valve core 15 abutting against the flat surface of the first valve core 14 is set to φe, the second valve core 15 is forced towards... Figure 3 The magnitude of the force pushing up from the upper middle part, i.e., the opposite side of the valve seat component, is the value obtained by multiplying the area of ​​the circle with diameter φe by the pressure in the flow path F.

[0065] Furthermore, the pressure within the flow path F acts on the opposite side, i.e., the back side, of the valve seat component of the main body 15a through the main body channel 15f. Figure 3 (above), and acts on the opposite side, i.e., the back side, of the valve seat component of the flange portion 15b through the flange portion channel 15g. Figure 3 (Above). The main body channel 15f and the flange channel 15g constitute a channel that guides the pressure in the flow path F to the back-side pressure-receiving part. Thus, the pressure in the flow path F acts on the back side of the main body 15a and the back side of the flange 15b as the back-side pressure-receiving part, applying force to the second valve core 15 towards the valve seat component. Therefore, the diameter of the flange 15b is φc, thus the second valve core 15 is... Figure 3The magnitude of the force applied to the lower part of the valve seat component is the value obtained by multiplying the area of ​​the circle with diameter φc by the pressure in the flow path F.

[0066] The protrusion 15c2 in the annular protrusion 15c protrudes from the lower end of the base 15c1, whose diameter is larger than the outer diameter of the flange portion 15b. Therefore, the inner diameter φe of the protrusion 15c2 in the second valve core 15 abutting against the flat surface of the first valve core 14 is larger than the outer diameter φc of the flange portion 15b in the second valve core 15. As a result, the pressure in the flow path F always pushes the second valve core 15 upwards, away from the valve seat component 13 and the first valve core 14.

[0067] Therefore, when no force other than the pressure in the flow path F acts on the second valve core 15, the second valve core 15 is away from the valve seat component 13 and the first valve core 14, but will be subjected to a thrust from the downward direction of the solenoid S.

[0068] In the above-described manner, when the buffer D, which is attempting to flow from the compression chamber R2 to the extension chamber R1, contracts, if the force pushing up the second valve core 15 due to the pressure within the flow path F exceeds the thrust of the solenoid S pressing down on the second valve core 15, the second valve core 15 moves away from the first valve core 14, and the solenoid valve V opens. Thus, in the solenoid valve V of this embodiment, during the contraction of the buffer D, the opening pressure can be adjusted by adjusting the thrust applied by the solenoid S in the pressing direction of the second valve core 15.

[0069] Next, the control valve 21, which adjusts the pressure of the back pressure chamber P, includes: a control valve body 22, which is axially movable and inserted into the valve hole 15d of the second valve core 15; and a control valve seat 15e, which is formed at the upper end of the main body 15a, i.e., the back side end, and surrounding the valve hole 15d. The control valve body 22 of the control valve 21 is pushed to the control valve seat 15e by the thrust from the solenoid S, and the valve opening pressure can be changed by adjusting the thrust of the solenoid S.

[0070] Specifically, the control valve body 22 is cylindrical and includes a flange-shaped valve portion 22a located at the base end. Figure 3 The upper middle end; the front end 22b, is inserted into the valve hole 15d in the second valve core 15 and slides in contact with the inner circumference of the valve hole 15d; the annular groove 22c is provided on the outer circumference and between the valve part 22a and the front end 22b; and the throttling hole 22d is provided on the inner circumference.

[0071] The outer diameter of valve part 22a is larger than the inner diameter of valve hole 15d, and the outer diameter of valve part 22a is larger than the inner diameter of valve hole 15d. Figure 3 The lower end faces the control valve seat 15e of the second valve core 15 in the axial direction (vertical direction). Furthermore, when the control valve body 22 is inserted into the valve hole 15d, the outer periphery of the front end 22b slides in contact with the inner periphery of the valve hole 15d, allowing it to move relative to the second valve core 15 in the axial direction (vertical direction). Figure 3 It moves up and down, and aligns the annular groove 22c with the opening of the pressure control channel 15h that connects to the back pressure chamber P.

[0072] Therefore, the control valve 21 causes the valve part 22a to... Figure 3 When the lower end abuts against the control valve seat 15e and closes the opening of the valve orifice 15d, the valve closes, cutting off the back pressure chamber P from the second valve core 15. Figure 3 The connection of the upper and middle side space, the upward movement of the valve body 22 within the valve hole 15d, and the valve part 22a Figure 3 When the lower end is far from the control valve seat 15e, the valve opens and connects the back pressure chamber P with the second valve core 15 through the annular groove 22c. Figure 3 The space on the upper middle side.

[0073] Second valve core 15 Figure 3 The space on the upper middle side is connected to the flow path F through the main body channel 15f, so when the control valve 21 is opened, the back pressure chamber P is connected to the compression side chamber R2.

[0074] The back pressure chamber P is connected to the extension side chamber R1 via the pilot channel 12i. A check valve 20 is provided in the flange channel 15g. Therefore, when the buffer D extends, the pressure in the extension side chamber R1 is reduced through the pilot channel 12i and introduced into the back pressure chamber P. When the pressure in the back pressure chamber P reaches the opening pressure of the control valve 21, the control valve 21 opens, connecting the back pressure chamber P to the compression side chamber R2. Therefore, the pressure in the back pressure chamber P is controlled to be equal to the opening pressure of the control valve 21. The opening pressure of the control valve 21 is adjusted by the solenoid S, therefore the pressure in the back pressure chamber P is also controlled by the solenoid S.

[0075] On the other hand, during the retraction of the buffer D, the check valve 20 opens, thus the pressure within the valve core support 12 acts on the back pressure chamber P via the flange passage 15g. Furthermore, the pressure within the valve core support 12 acts on the second valve core 15 via the body passage 15f. Figure 3 The pressure within the valve core support 12 in the space above and in the middle also acts on the valve body 22 of the control valve. Figure 3 At the upper middle end, when the buffer D retracts, the control valve 21 causes the valve part 22a to sit on the control valve seat 15e and maintain the closed valve state.

[0076] Furthermore, a throttling orifice 22d is provided on the inner circumference of the control valve body 22. The space below the front end 22b of the valve orifice 15d opens to the outside of the valve orifice 15d through the throttling orifice 22d. Therefore, the control valve body 22 can move within the valve orifice 15d, and its rapid axial movement relative to the second valve core 15 is suppressed. Thus, in the buffer D of this embodiment, the pressure fluctuation of the back pressure chamber P caused by the repeated minute opening and closing of the control valve 21 can be suppressed.

[0077] Next, the solenoid S in this embodiment is composed of the following components: a coil 40, which is housed in the housing 2b of the piston rod 2 in an axial manner; a first fixed iron core 41, which is disposed above the coil 40; a second fixed iron core 42, which is disposed below the coil 40 at a distance from the first fixed iron core 41; a first movable iron core 43, which is disposed between the first fixed iron core 41 and the second fixed iron core 42 and is attracted by the first fixed iron core 41 when the coil 40 is energized; a second movable iron core 44, which is disposed between the first fixed iron core 41 and the second fixed iron core 42 and is attracted by the second fixed iron core 42 when the coil 40 is energized; and a spring 45, which applies force to the first movable iron core 43 toward the second fixed iron core 42.

[0078] The following is a detailed description of each part of the solenoid S constituting this embodiment. For example... Figure 2 As shown, the coil 40 is housed within a resin housing 50. The resin housing 50 includes a cylindrical portion 50a for housing the coil 40, and bridging members 50b spanning two points at the upper end of the cylindrical portion 50a, and internally containing wiring 51 connected to the coil 40. The resin housing 50 is formed by injection molding molding resin into the mold after housing the coil 40 within the mold, and internally contains the coil 40 and wiring 51 connected to both ends of the coil 40.

[0079] Wiring 51 extends upward from the center of the bridging member 50b. Although not shown in the figure, it passes through the rod body 2a of the piston rod 2 and is pulled out from the upper end of the rod body 2a to the buffer D. It is connected to the power supply outside the figure through an externally provided drive circuit.

[0080] The first fixed iron core 41 consists of the following two parts: a stop 41a, which is a soft magnetic material, is fitted into the inner circumference of the upper end side of the cylindrical portion 50a in the resin housing 50; and a disc-shaped base 41b, which is formed of a soft magnetic material, is stacked on the upper end of the cylindrical portion 50a and abuts against the stop 41a.

[0081] The stop block 41a is disc-shaped and has a flange 41a1 at the upper end of its outer periphery, an annular groove 41a2 at the outer periphery, and a recess 41a3 at the center of its lower end. The stop block 41a causes the outer periphery of the flange 41a1 to fit into the inner periphery of the cylindrical portion 50a of the resin housing 50, and is radially positioned by the resin housing 50 in a manner concentric with the coil 40.

[0082] The stop block 41a and the guide tube 46, which is made of a non-magnetic material and is located on the inner circumference of the coil 40 and fitted into the inner circumference of the cylindrical portion 50a, are inserted into the cylindrical portion 50a together. The lower side of the flange 41a1 is fitted into the guide tube 46. Figure 2 The upper inner circumference. The annular groove 41a2 of the stop block 41a accommodates the sealing ring 47, which is in close contact with the inner circumference of the guide tube 46, thus sealing the stop block 41a and the guide tube 46.

[0083] The base 41b is disc-shaped and has a cutout 41b1 that opens from the side to accommodate the bridging member 50b of the resin housing 50. The bridging member 50b is inserted into the cutout 41b1 from the side of the resin housing 50, overlapping with the upper end of the cylindrical portion 50a, and thus mounted on the resin housing 50. When the base 41b is stacked on the upper end of the cylindrical portion 50a, it abuts against the upper end face of the stop block 41a housed within the cylindrical portion 50a, and cooperates with the stop block 41a to form the first fixed iron core 41. When the first fixed iron core 41 is mounted on the resin housing 50, it is positioned axially above the coil 40. Furthermore, when the base 41b is housed within the outer casing 2b, its upper end abuts against the top 2b1 of the outer casing 2b.

[0084] The second fixed iron core 42 is formed of a soft magnetic material and is generally annular. It includes: a fitting portion 42a, which is inserted into the inner circumference of the cylindrical portion 50a containing the coil 40 of the resin housing 50 and fitted into the guide tube 46; a flange portion 42b, which is connected to the fitting portion 42a and abuts against the lower end of the cylindrical portion 50a; an annular groove 42c, which is formed on the outer circumference of the flange portion 42b; and an annular insertion port 42d, which protrudes from the inner circumference side of the fitting portion 42a toward the first fixed iron core side.

[0085] The fitting portion 42a is fitted into the lower inner circumference of the guide tube 46, which is fitted into the inner circumference of the cylindrical portion 50a. Thus, the second fixed iron core 42 is radially positioned concentrically with the coil 40 by the resin housing 50 via the guide tube 46. Furthermore, a sealing ring 48 is provided between the outer circumference of the socket 42d and the guide tube 46, and the sealing ring 48 is in close contact with both the outer circumference of the socket 42d and the inner circumference of the guide tube 46, thereby sealing the second fixed iron core 42 and the guide tube 46. Additionally, an annular protrusion 46a is provided on the inner circumference of the guide tube 46 to prevent the sealing ring 48 from falling out between the socket 42d and the guide tube 46.

[0086] The flange portion 42b abuts against the lower end of the cylindrical portion 50a of the resin housing 50 and is fitted into the cylindrical portion 2b2 of the outer casing 2b. Furthermore, a sealing ring 49 is accommodated within the annular groove 42c of the flange portion 42b. Because the sealing ring 49 is in close contact with the inner circumference of the cylindrical portion 2b2, a seal is formed between the second fixing core 42 and the outer casing 2b. Furthermore, within the inner circumference of the second fixing core 42, a sealing ring 49 is fitted into the cylindrical portion 2b2. Figure 2 The push rod 55 on the inner circumference of the upper middle part can be axially moved and inserted into the control valve body 22 in the control valve 21.

[0087] like Figure 2 As shown, the first movable iron core 43 includes: an outer cylinder 43a, having a cylindrical guide portion 43a1 that slides in contact with the inner circumference of the guide tube 46, and an annular bottom 43a2 extending radially inward from the inner circumference of the guide portion 43a1, formed of a soft magnetic material; and a cup-shaped inner cylinder 43b, formed of a non-magnetic material, fitted into the inner circumference of the bottom 43a2 in the outer cylinder 43a.

[0088] The inner cylinder 43b has a flange 43b1 on its upper outer periphery and a hole 43b2 at its bottom connecting the inside and outside of the inner cylinder 43b, fitting into the inner periphery of the bottom 43a2 of the outer cylinder 43a. An annular recess 43a3 is provided on the upper inner periphery of the bottom 43a2 of the outer cylinder 43a to fit the flange 43b1. When the inner cylinder 43b is installed on the outer cylinder 43a, the upper end of the flange 43b1 and the upper end of the bottom 43a2 are on the same plane.

[0089] Furthermore, when the first movable iron core 43 is inserted into the guide tube 46, the interior of the inner cylinder 43b of the first movable iron core 43 and the recess 41a3 of the stop block 41a in the first fixed iron core 41 are axially aligned. Moreover, a spring 45 is accommodated between the bottom of the inner cylinder 43b and the bottom surface of the recess 41a3 of the stop block 41a. In a compressed state, the spring 45 is installed between the first movable iron core 43 and the first fixed iron core 41, constantly applying force to the first movable iron core 43 towards the second fixed iron core 42.

[0090] Furthermore, the first movable iron core 43 slides in contact with the guide tube 46, but the space between the first fixed iron core 41 and the first movable iron core 43 communicates with the space further below the first movable iron core 43 through the hole 43b2 in the inner cylinder 43b. Therefore, when the first movable iron core 43 moves axially within the guide tube 46, the liquid filled in the cylinder 1 enters and exits through the hole 43b2 within the space between the first fixed iron core 41 and the first movable iron core 43. Thus, the space between the first fixed iron core 41 and the first movable iron core 43 is not sealed, allowing the first movable iron core 43 to move smoothly within the coil 40. Additionally, the hole 43b2 has a cross-sectional area designed to resist the flow of liquid, and it resists the flow of liquid as the first movable iron core 43 moves axially up and down, thereby suppressing rapid movement of the first movable iron core 43.

[0091] The second movable iron core 44 is formed of a soft magnetic material, such as Figure 2 As shown, the device is a bottomed cylindrical structure with a sliding cylinder 44a that slides in contact with the inner circumference of the guide portion 43a1 of the first movable iron core 43, and a cover portion 44b that closes the lower end of the sliding cylinder 44a. The outer circumference of the lower end is slidably inserted into the inner circumference of the insertion port 42d of the second fixed iron core 42, and can move axially within the coil 40 and between the first fixed iron core 41 and the second fixed iron core 42. Furthermore, the lower end of the cover portion 44b of the second movable iron core 44 abuts against the upper end of the push rod 55, which is axially inserted into the inner circumference of the second fixed iron core 42. When the coil 40 is energized to apply a pushing force to the second movable iron core 44, the pushing force is applied to the control valve body 22 in the control valve 21 via the push rod 55.

[0092] The second movable iron core 44 is radially aligned by the guide portion 43a1 of the first movable iron core 43, and the first movable iron core 43 is radially aligned by the guide tube 46. The guide tube 46 is fitted inside the cylindrical portion 50a containing the coil 40, so it can remain coaxial with the first movable iron core 43 relative to the coil 40 and move axially relative to each other.

[0093] Furthermore, the second movable iron core 44 has a connecting hole 44c in the cover portion 44b that connects the inside and outside of the second movable iron core 44, and the space between the second movable iron core 44 and the first movable iron core 43 communicates with the space further below the second movable iron core 44. Therefore, when the second movable iron core 44 moves axially relative to the first fixed iron core 41, the liquid filled in the cylinder 1 enters and exits through the connecting hole 44c in the space between the first movable iron core 43 and the second movable iron core 44. Therefore, the space between the first movable iron core 43 and the second movable iron core 44 is not sealed, and the second movable iron core 44 can move smoothly within the coil 40. In addition, the connecting hole 44c has a cross-sectional area set in a way that can apply resistance to the flow of liquid, and applies resistance to the flow of liquid when the second movable iron core 44 moves up and down axially, thus suppressing rapid movement of the second movable iron core 44.

[0094] Furthermore, in the buffer D of this embodiment, the inner circumference of the second fixed iron core 42 Figure 2 A stepped portion 42e is provided on the inner circumference of the second fixed iron core 42, with an expanded diameter on the upper side. A helical spring 52 is provided between the stepped portion 42e and the cover portion 44b of the second movable iron core 44. The helical spring 52 always applies force to the second movable iron core 44 towards the first fixed iron core 41, and is in a compressed state due to the force of the spring 45 when the coil 40 is not energized. Furthermore, when the coil 40 is not energized, the first movable iron core 43 and the second movable iron core 44 are sandwiched between the spring 45 and the helical spring 52, reaching their closest possible position.

[0095] Furthermore, an annular limiting member 53 is provided between the bottom 43a2 of the first movable iron core 43 and the sliding cylinder 44a of the second movable iron core 44 to prevent mutual adsorption. Even when the second movable iron core 44 and the first movable iron core 43 are closest to each other, the limiting member 53 prevents the bottom 43a2 from directly contacting the sliding cylinder 44a. The limiting member 53 can be installed on either the first movable iron core 43 or the second movable iron core 44. Additionally, an annular limiting member 54 is provided on the inner circumference of the upper end of the fitting portion 42a of the second fixed iron core 42 to prevent the second fixed iron core 42 and the second movable iron core 44 from adsorbing each other. The limiting member 54 can be installed on the second movable iron core 44. The limiting members 53 and 54 can be non-magnetic materials and can be formed of rubber or the like to function as cushioning materials.

[0096] The coil 40, the first fixed iron core 41, the second fixed iron core 42, the first movable iron core 43, the second movable iron core 44, and the spring 45 constituting the solenoid S constructed in the above manner are housed in the outer casing 2b of the piston rod 2. When the valve core bracket 12 is threadedly engaged with the threaded portion 2b3 located on the lower inner circumference of the cylindrical portion 2b2 of the outer casing 2b, it is clamped and fixed in the outer casing 2b by the top 2b1 and the valve core bracket 12.

[0097] When the coil 40 is not energized, the helical spring 52 contracts due to the force of the spring 45, and the first movable iron core 43 and the second movable iron core 44 are closest to each other and are positioned at the lowest position closest to the second fixed iron core 42.

[0098] On the other hand, when the coil 40 is energized, the magnetic flux passes through the magnetic circuit formed by the first fixed iron core 41, the first movable iron core 43, the second movable iron core 44, the second fixed iron core 42, and the outer casing 2b, generating a magnetic force that attracts the first movable iron core 43 and the first fixed iron core 41, thus applying an upward force to the first movable iron core 43, and generating a magnetic force that attracts the second movable iron core 44 and the second fixed iron core 42, thus applying a downward force to the second movable iron core 44. Moreover, the magnitude of the upward force on the first movable iron core 43 and the downward force on the second movable iron core 44 can be adjusted according to the amount of current flowing through the coil 40. In addition, the lower outer periphery of the second movable iron core 44 slides in contact with the inner side of the annular socket 42d provided on the second fixed iron core 42. Therefore, when the coil 40 is energized, the second movable iron core 44 is attracted by the second fixed iron core 42 and will not move toward the first fixed iron core 41 together with the first movable iron core 43.

[0099] The limiting member 53 prevents the bottom 43a2 of the first movable iron core 43 from directly contacting the sliding cylinder 44a of the second movable iron core 44, and prevents the first movable iron core 43 and the second movable iron core 44 from attracting each other when energizing the coil 40 begins. Therefore, when the coil 40 is energized, the first movable iron core 43 and the second movable iron core 44 can quickly move in a direction separating from each other. When the coil 40 is energized and the second movable iron core 44 is attracted by the second fixed iron core 42, the limiting member 54 prevents the upper end of the fitting portion 42a of the second fixed iron core 42 from directly contacting the lower end of the second movable iron core 44, preventing the second fixed iron core 42 and the second movable iron core 44 from attracting each other. Therefore, if the current flowing through the coil 40 is reduced, the second movable iron core 44 can quickly move away from the second fixed iron core 42. Furthermore, the close-fitting length of the helical spring 52 is less than the axial length from the upper end of the limiting member 54 to the step 42e. Even when the coil 40 is energized and the second movable iron core 44 is attracted by the second fixed iron core 42 and the limiting member 54 is clamped by the two, it will not fully retract, thus not hindering the second movable iron core 44 from abutting against the limiting member 54. Although the helical spring 52 can be omitted, by providing the helical spring 52, when the coil 40 is energized and the first movable iron core 43 is attracted by the first fixed iron core 41, the rapid displacement of the second movable iron core 44 towards the second fixed iron core 42 can be suppressed, thereby suppressing the vibratory opening and closing of the solenoid valve V caused by the rapid movement of the second movable iron core 44.

[0100] Next, the operation of solenoid S will be explained. Figure 4 This indicates the relationship between the current supplied to the solenoid S and the force exerted by the solenoid S on the control valve body 22. Figure 4 In this context, Ia represents the minimum current required from the state where the coil 40 is not energized, the first movable iron core 43 and the second movable iron core 44 are closest to each other and furthest from the first fixed iron core 41, to the minimum current required to energize the coil 40 so that the first movable iron core 43 is attracted to the first fixed iron core 41. Ib represents the minimum current required to maintain the attraction between the first fixed iron core 41 and the first movable iron core 43 after the coil 40 is energized and the first movable iron core 43 is attracted to the first fixed iron core 41. Furthermore, Ic will be described below.

[0101] First, when the current supplied to coil 40 is zero, that is, when solenoid S is not energized, the first movable iron core 43 is pressed down by the force of spring 45 and contacts the second movable iron core 44 via limiting member 53. The second movable iron core 44 is pressed down together with push rod 55, thus solenoid S provides a force in the closing direction to control valve body 22. Thus, when solenoid S is not energized, the force of spring 45 exerts a downward force on control valve body 22 via push rod 55, second movable iron core 44, limiting member 53, and first movable iron core 43. In the buffer D of this embodiment, the force pushing control valve body 22 downward becomes the direction for closing control valve body 22. Therefore, when solenoid S is not energized, the force of spring 45 exerts a force on control valve body 22 in the direction for closing control valve body 22.

[0102] Secondly, when the current supplied to the coil 40 is increased, the upward force attracting the first movable iron core 43 to the first fixed iron core 41 increases, and the downward force attracting the second movable iron core 44 to the second fixed iron core 42 also increases. In this case, in the region where the current supplied to the solenoid S is less than Ia, although the force of the spring 45 is transmitted to the control valve body 22, part of the downward force of the spring 45 on the first movable iron core 43 is offset by the upward force attracting the first movable iron core 43 (on the side of the first fixed iron core 41). Therefore, in the region where the current is less than Ia, the greater the current supplied to the solenoid S, the less the downward thrust exerted by the solenoid S on the control valve body 22.

[0103] On the other hand, when the current supplied to the coil 40 is increased, in the region where the current is Ia or higher, the first movable iron core 43 will resist the force of the spring 45 and be attracted to the first fixed iron core 41 and attached thereto. In this state, the force of the spring 45 will not be transmitted to the second movable iron core 44; only the force that attracts the second movable iron core 44 to the second fixed iron core 42 acts as a downward thrust to the control valve body 22. The downward force attracting the second movable iron core 44 increases proportionally to the current supplied to the coil 40. Therefore, in the region where the current supplied to the coil 40 is Ia or higher, the more the current supplied to the coil 40 is increased, the more proportionally the downward thrust exerted by the solenoid S on the control valve body 22 increases.

[0104] Conversely, when the current supplied to the coil 40 decreases, the upward force attracting the first movable iron core 43 to the first fixed iron core 41 decreases, and the downward force attracting the second movable iron core 44 to the second fixed iron core 42 also decreases. Even in this case, in the region where the current supplied to the coil 40 is Ib or more, the first movable iron core 43 is attracted by the first fixed iron core 41, maintaining the state where the force of the spring 45 is not transmitted to the second movable iron core 44. Therefore, in the region where the current supplied to the coil 40 is Ib or more, the more the current supplied to the coil 40 is reduced, the more proportionally the downward thrust exerted by the solenoid S on the control valve body 22 decreases.

[0105] On the other hand, when the current supplied to the coil 40 is reduced, in the region where the current is less than Ib, the attraction between the first movable iron core 43 and the first fixed iron core 41 is released due to the force of the spring 45, and the force of the spring 45 is transmitted to the second movable iron core 44. Therefore, in the region where the current is less than Ib, the more the current supplied to the coil 40 is reduced, the more the downward thrust exerted by the solenoid S on the control valve body 22 increases.

[0106] Depend on Figure 4 It is known that the minimum current required to maintain the adsorption of the first movable iron core 43 and the first fixed iron core 41, i.e., Ib, is less than the minimum current required to adsorb the first movable iron core 43, which is in a separated state, onto the first fixed iron core 41, i.e., Ia (Ia>Ib). Therefore, the force applied by the solenoid S to the control valve body 22 has a hysteresis characteristic relative to the current supplied to the coil 40. Furthermore, Figure 4 In the text, for ease of understanding, the area where the current supplied to the solenoid S is relatively small is exaggerated.

[0107] Furthermore, in this embodiment, when attempting to control the amount of current supplied to the coil 40 to control the thrust applied by the solenoid S to the control valve body 22, a current of Ia or higher is first supplied to cause the first movable iron core 43 to adhere to the first fixed iron core 41, and then the amount of current supplied to the coil 40 is controlled within a range greater than Ib and greater than Ic. Thus, under normal conditions of controlling the current flow to the solenoid S, the first movable iron core 43 will remain adhered to the first fixed iron core 41. Therefore, the amount of current supplied to the solenoid S is proportional to the downward thrust applied by the solenoid S to the control valve body 22; the greater the current supplied to the coil 40, the greater the thrust.

[0108] Thus, in the buffer D of this embodiment, the current supplied to the coil 40 is proportional to the thrust applied by the solenoid S to the control valve body 22. The greater the supply current, the greater the thrust, and the less the supply current, the smaller the thrust.

[0109] On the other hand, during a fault where the energization of the solenoid S is cut off, the control valve body 22 is subjected to a downward force by the spring 45 of the solenoid S. This force is predetermined based on the spring constant and other specifications of the spring 45. Furthermore, during a fault (when no energization is applied), the direction of the force exerted on the control valve body 22 by the spring 45 is the same as the direction of the thrust exerted on the control valve body 22 by the solenoid S during normal operation.

[0110] Next, the operation of the buffer D in this embodiment will be explained. When the buffer D extends, the piston 3 moves relative to the cylinder 1... Figure 1 When moving upwards, as piston 3 moves relative to cylinder 1, the liquid in the compressed elongated side chamber R1 attempts to move through flow path F to the enlarged compression side chamber R2.

[0111] When the pressure in the extension chamber R1 of the solenoid valve V reaches the opening pressure during the extension action of the buffer D, the first valve core 14 and the second valve core 15 leave the valve seat component 13, thus connecting the connecting hole 12j with the port 13c. The opening pressure of the solenoid valve V, as previously described, varies according to the pressure change in the back pressure chamber P controlled by the control valve 21. More specifically, the solenoid S can change the thrust exerted on the control valve body 22 in the closing direction according to the current supplied to the coil 40. Therefore, when the current supplied to the solenoid S is Ib, the solenoid valve V will minimize the opening pressure of the control valve 21 and control the pressure in the back pressure chamber P as much as possible, thus minimizing the opening pressure when the first valve core 14 leaves the valve seat component 13.

[0112] In this state, the liquid in the extension chamber R1 passes through the connecting hole 12j, the solenoid valve V, and the port 13c, pushes open the extension soft valve 18, and moves towards the compression chamber R2 through the extension side channel 3e of the piston 3. Therefore, during the extension action of the buffer D, when the solenoid valve V has its opening pressure minimized, the extension soft valve 18 mainly exerts resistance on the flow of liquid from the extension chamber R1 towards the compression chamber R2, generating a soft damping force that hinders the extension action of the buffer D.

[0113] Furthermore, when the current supplied to the solenoid S is increased during the extension action of the buffer D, the thrust exerted by the solenoid S on the control valve 21 is increased, thereby increasing the pressure in the back pressure chamber P. In other words, the buffer D will generate a damping force corresponding to the opening pressure of the solenoid valve V. Figure 5 As shown, if the current supplied to the solenoid S is increased, the resistance exerted by the solenoid valve V on the flow of liquid from the extension side chamber R1 to the compression side chamber R2 increases. Therefore, the damping force generated by the buffer D can be adjusted according to the current supplied to the solenoid S. In the buffer D of this embodiment, when the buffer D extends, increasing the current supplied to the solenoid S increases the pressure in the back pressure chamber P. Therefore, the damping force that hinders the extension of the buffer D can increase with the increase of the current supplied to the solenoid S. Furthermore, even when the solenoid valve V is closed, the liquid can pass through the flow path F through the throttling orifice provided in the annular valve seat 13d or the annular protrusion 15c. During the period when the solenoid valve V is closed, the buffer D generates a damping force through the throttling orifice.

[0114] Furthermore, if the extension speed of the buffer D is increased while increasing the damping force during the extension action, the flow rate of the liquid from the extension side chamber R1 through the connecting hole 12j through the narrow gap between the first valve core 14 and the annular valve seat 13d tends to increase and the pressure in the gap decreases. This reduces the force with which the first valve core 14 leaves the valve seat component 13 and narrows the gap between the first valve core 14 and the annular valve seat 13d, potentially generating a damping force higher than the required damping force. To address this issue, in the solenoid valve V of this embodiment, the area of ​​the hole 16c provided on the guide cylinder 16b of the guide member 16 is reduced. When the flow rate of the liquid passing through the hole 16c is high, pressure loss occurs, increasing the pressure on the outer periphery of the guide cylinder 16b and the space between the valve seat member 13 and the first valve core 14. This increases the force pushing the first valve core 14 away from the valve seat member 13, thus preventing the gap between the first valve core 14 and the annular valve seat 13d from decreasing even if the liquid flow rate increases. According to the solenoid valve V constructed in this way, even with increased damping force during the extension action of the buffer D, the gap between the first valve core 14 and the annular valve seat 13d does not decrease as the extension speed of the buffer D increases. Therefore, even with high-speed extension, excessive damping force of the buffer D can be prevented, thereby improving vehicle ride comfort. Furthermore, instead of providing the hole 16c in the guide cylinder 16b, such as... Figure 3 As shown, an axially penetrating slit 14a can be provided on the inner circumferential side of the portion of the first valve core 14 that abuts against the annular valve seat 13d. Through this slit 14a, the space on the outer circumferential side of the guide cylinder 16b, which is closer to the valve seat component than the first valve core 14, is connected to the interior of the guide cylinder 16b via the space above the first valve core 14. Even so, when the extension speed of the buffer D is accelerated while increasing the damping force during the extension action of the buffer D, pressure loss occurs when the liquid passes through the slit 14a, causing the pressure in the space to rise and increasing the force of the first valve core 14 leaving the valve seat component 13. The gap between the first valve core 14 and the annular valve seat 13d does not decrease. Therefore, even with high-speed extension action, excessive damping force of the buffer D can be suppressed, thereby improving the ride comfort of the vehicle. Additionally, as mentioned earlier, a hole 16c is provided in the guide cylinder 16b to connect the space on the outer periphery of the guide cylinder 16b, which is closer to the valve seat component than the first valve core 14, with the interior of the guide cylinder 16b. However, in addition to the hole 16c, the connection can also be made through a cut. Furthermore, a cut 14a is provided in the first valve core 14 to connect the space on the outer periphery of the guide cylinder 16b, which is closer to the valve seat component than the first valve core 14, with the interior of the guide cylinder 16b. However, in addition to the cut 14a, the connection can also be made through a hole.

[0115] In addition, when the buffer D extends, the piston rod 2 exits from the cylinder 1, and the volume pushed open by the piston rod 2 in the cylinder 1 decreases. However, the gas chamber G is expanded by the free piston 11 moving upward in the cylinder 1, thereby compensating for the reduction in volume.

[0116] Furthermore, when the buffer D retracts, the piston 3 moves relative to the cylinder 1. Figure 1 When moving downwards, due to the movement of piston 3 relative to cylinder 1, the liquid in the compressed side chamber R2 attempts to move through the flow path F to the enlarged elongated side chamber R1.

[0117] When the buffer D contracts, the liquid in the compression chamber R2 flows into the flow path F through the compression side soft valve 19 pushed open by the compression side channel 3d of the piston 3. As a result, the pressure in the compression chamber R2 decreases and is transmitted into the flow path F.

[0118] During the retraction of the buffer D, the pressure within the valve core support 12 acts on the first valve core 14, pressing it against the valve seat component 13. Simultaneously, the pressure within the valve core support 12 acts on both the front side of the second valve core 15 on the valve seat component side and the back side on the opposite side of the valve seat component. The pressure-bearing area (area of ​​diameter φe) on the front side of the second valve core 15 is larger than the pressure-bearing area (area of ​​a circle with diameter φc) on the back side. Therefore, due to the pressure within the flow path F, the second valve core 15 is subjected to pressure in a direction away from the valve seat component 13 and the first valve core 14. Figure 2 The force (upper middle).

[0119] Regardless of whether coil 40 is energized, solenoid S directs... Figure 2 The lower middle part, i.e., the side of the second valve core 15, applies a thrust to the control valve body 22. During the retraction of the buffer D, the pressure within the valve core support 12 is transmitted through the main body channel 15f to the back side of the second valve core 15. The control valve body 22 is pushed towards the second valve core 15 by the pressure within the valve core support 12, resulting in the valve part 22a abutting against the control valve seat 15e of the second valve core 15. The solenoid S applies a thrust to the control valve body 22 both when energized and when not energized. Figure 3 The downward thrust of the solenoid S is thus applied to the second valve core 15 via the control valve body 22.

[0120] Therefore, under the pressure within the valve core support 12, the second valve core 15... Figure 3 When the force pushing up exceeds the thrust of the solenoid S, the second valve core 15 moves away from the first valve core 14, and the solenoid valve V opens, allowing port 13c to connect with the connecting hole 12j, thus allowing the flow of liquid from the compression side chamber R2 toward the extension side chamber R1.

[0121] Thus, during the contraction of the buffer D, when the compression-side soft valve 19 opens, and the pressure in the flow path F connected to the compression-side chamber R2 reaches the opening pressure of the solenoid valve V, the solenoid valve V opens, and the second valve core 15 leaves the first valve core 14, connecting the connecting hole 12j to the port 13c. As mentioned above, the opening pressure of the solenoid valve V changes according to the thrust of the solenoid S. More specifically, the thrust of the solenoid S can be changed according to the amount of current supplied to the coil 40. Therefore, when the amount of current supplied to the solenoid S is set to Ib, the thrust of the solenoid valve V is minimized, thereby reducing the opening pressure when the second valve core 15 leaves the first valve core 14 to the lowest level. In addition, before the solenoid valve V opens, the liquid in the compression-side chamber R2, after passing through the compression-side channel 3d and the compression-side soft valve 19, will move towards the extension-side chamber R1 through the flange channel 15g, the check valve 20, and the pilot channel 12i. When the buffer D contracts at a very low speed, the throttling section O1 of the pilot channel 12i exerts minimal resistance on the liquid flow. Therefore, a damping force is generated by the soft valve 19 on the compression side. If the contraction speed of the buffer D increases, the liquid has difficulty passing through the throttling section O1, thus the pressure in the flow path F rises, and the solenoid valve V opens. Therefore, the pilot channel 12i has a small effect on the soft damping force, and the pilot channel 12i also has no significant effect on the damping force adjusted in the solenoid valve V.

[0122] In this state, the liquid in the compression chamber R2 moves towards the extension chamber R1 through the flow path F and the solenoid valve V after passing through the compression soft valve 19. However, the resistance exerted by the solenoid valve V on the liquid flow is reduced. Therefore, when the buffer D retracts, when the solenoid valve V has its opening pressure minimized, the compression soft valve 19 mainly exerts resistance on the flow of liquid from the compression chamber R2 towards the extension chamber R1, generating a soft damping force that hinders the retraction of the buffer D. Furthermore, in the solenoid valve V of this embodiment, the area of ​​the front pressure-bearing portion of the second valve core 15 is larger than the area of ​​the back pressure-bearing portion. Therefore, when the buffer D retracts, the second valve core 15 will inevitably be subjected to a force away from the first valve core 14 due to the pressure acting through the flow path F. Therefore, according to the solenoid valve V of this embodiment, when the thrust of the solenoid S is reduced and the opening pressure of the solenoid valve V is reduced, the damping force generated in soft mode can be reduced compared with conventional solenoid valves, thereby improving the ride comfort of the vehicle.

[0123] Furthermore, if the current supplied to solenoid S is increased during the retraction of buffer D, and the thrust of solenoid S is increased, then buffer D will generate a damping force corresponding to the opening pressure of solenoid valve V. In other words, if... Figure 5As shown, if the current supplied to the solenoid S is increased, the resistance exerted by the solenoid valve V on the flow of liquid from the compression chamber R2 to the extension chamber R1 increases. Therefore, the damping force generated by the buffer D can be adjusted according to the current supplied to the solenoid S. In the buffer D of this embodiment, if the current supplied to the solenoid S is increased during the contraction action of the buffer D, the opening pressure of the solenoid valve V can be increased. Therefore, as the current supplied to the solenoid S increases, the damping force that hinders the contraction action of the buffer D can be increased. In addition, even when the solenoid valve V is closed, the liquid can pass through the flow path F through the throttling orifice provided in the annular valve seat 13d or the annular protrusion 15c. During the closure of the solenoid valve V, the buffer D generates a damping force through the throttling orifice.

[0124] In addition, during the retraction action of the buffer D, the piston rod 2 enters the cylinder 1, and the volume pushed open by the piston rod 2 in the cylinder 1 increases. However, the increase in volume is compensated by the downward movement of the free piston 11 in the cylinder 1 to shrink the gas chamber G.

[0125] The solenoid valve V of this embodiment includes: a valve seat component 13 having an annular valve seat 13d surrounding the flow path F; an annular first valve core 14 axially movable relative to the valve seat component 13 and capable of opening and closing the flow path F by disengaging from and repositioning relative to the annular valve seat 13d; a second valve core 15 axially movable relative to the valve seat component 13 and the first valve core 14, stacked on the opposite side of the valve seat component of the first valve core 14, and capable of opening and closing the flow path F by disengaging from and repositioning relative to the first valve core 14; and a solenoid S capable of applying a pushing force to the second valve core 15 towards the valve seat component; the first valve core 14 and the second valve core 15 are affected by the pressure (one) on the extended side chamber R1 of the flow path F. The second valve core 15 is subjected to a force in the direction away from the valve seat component 13, which is applied together with the pressure on the compression side chamber R2 side of the flow path F (the other side pressure), and is subjected to a force in the direction of separation from each other. The second valve core 15 has: a front side pressure-bearing portion, which acts as a force away from the valve seat component 13 due to the pressure in the flow path F facing the valve seat component; a back side pressure-bearing portion, which acts as a force in the direction of approaching the valve seat component due to the pressure acting on the opposite side facing the valve seat component; and a main body channel 15f and a flange channel 15g, which guide the pressure in the flow path F to the back side pressure-bearing portion; the area of ​​the front side pressure-bearing portion is larger than the area of ​​the back side pressure-bearing portion.

[0126] In the solenoid valve V constructed in this manner, the area of ​​the front-side pressure-bearing portion of the second valve core 15 is larger than the area of ​​the back-side pressure-bearing portion. Therefore, during the contraction action, due to the pressure acting on the second valve core 15 through the flow path F, the second valve core 15 is subjected to a force in a direction away from the first valve core 14. Thus, when the thrust of the solenoid S is reduced, thereby reducing the opening pressure of the solenoid valve V, the damping force generated in soft mode can be reduced, improving the vehicle's ride comfort. Furthermore, by increasing the area of ​​the front-side pressure-bearing portion of the second valve core 15, the inner diameter of the portion of the second valve core 15 that abuts against the first valve core 14 becomes larger. Therefore, during the opening period when the second valve core 15 moves away from the first valve core 14, the area of ​​the gap formed between the first valve core 14 and the second valve core 15 becomes larger. Therefore, according to the solenoid valve V of this embodiment, during the opening period when the second valve core 15 leaves the first valve core 14, the area of ​​the gap formed between the first valve core 14 and the second valve core 15 increases, so the resistance of the liquid passing through the gap is effectively reduced, thereby generating a soft damping force.

[0127] Furthermore, in the solenoid valve V of this embodiment, the second valve core 15 has a main body portion 15a, a flange portion 15b provided on the outer periphery of the main body portion 15a, and an annular protrusion 15c protruding from the front side of the flange portion 15b and abutting against the first valve core 14. The back side pressure-bearing portion includes the valve seat component opposite end of the main body portion 15a and the valve seat component opposite end of the flange portion 15b. The channel has a straight main body channel 15f connecting the front side of the main body portion 15a and the back side of the main body portion 15a, and a straight flange portion channel 15g connecting the front side of the flange portion 15b and the inner side of the annular protrusion 15c and the back side of the flange portion.

[0128] According to the solenoid valve V constructed in this manner, by providing a straight main body channel 15f and a flange channel 15g in the second valve core 15, pressure is guided to the back side pressure-bearing portion of the second valve core 15. Therefore, the formation of the channel becomes easier, and the processing cost of the second valve core 15 can be reduced. Furthermore, in the solenoid valve V of this embodiment, a back pressure chamber P is provided on the back side of the flange portion 15b. When the buffer D contracts, the pressure on the compression side chamber R2 is guided to the back pressure chamber P via the flange channel 15g. The back pressure chamber P is connected to the extension side chamber R1 via the pilot channel 12i. By increasing the cross-sectional area of ​​the flange channel 15g relative to the throttling portion O1 in the pilot channel 12i, the damping force deviation caused by dimensional deviation can be reduced.

[0129] Furthermore, in the solenoid valve V of this embodiment, the main body channel 15f and the flange channel 15g are arranged parallel to the axis of the second valve core 15. Therefore, it is easier to process the opening of the main body channel 15f and the flange channel 15g in the second valve core 15. Compared with the case where the main body channel 15f and the flange channel 15g are inclined relative to the axis, the main body channel 15f and the flange channel 15g are shorter, and the space occupied by the main body channel 15f and the flange channel 15g in the second valve core 15 is also smaller. Therefore, the second valve core 15 can be miniaturized.

[0130] Furthermore, the solenoid valve V of this embodiment includes: a back pressure chamber P, which exerts pressure (one-sided pressure) on the extended side chamber R1 of the flow path F on the back side of the flange portion 15b; and a control valve 21, which receives thrust from the solenoid S to adjust the pressure of the back pressure chamber P; the second valve core 15 has a valve hole 15d opening from the back side of the main body portion 15a, and an annular control valve seat 15e provided on the back side of the main body portion 15a; the control valve 21 has a control valve body 22 that can be axially moved into the valve hole 15d and can be seated relative to the control valve seat 15e; the solenoid S applies thrust to the second valve core 15 when the control valve body 22 is seated in the control valve seat 15e.

[0131] According to the solenoid valve V constructed in this manner, when liquid flows from one side to the other in the flow path F, in this embodiment, when the buffer D extends, the pressure of the back pressure chamber P can be controlled by applying the thrust of the solenoid S to the control valve 21, so that the opening pressure of the solenoid valve V can be changed, thereby adjusting the damping force when the buffer D extends. And when liquid flows from one side to the other in the flow path F, in this embodiment, when the buffer D contracts, the opening pressure of the solenoid valve V can be changed by applying the thrust of the solenoid S to the second valve core 15 via the control valve body 22, thereby adjusting the damping force when the buffer D contracts.

[0132] Furthermore, the specific shape and structure of the valve seat component 13, the first valve core 14, and the second valve core 15 in the solenoid valve V can be designed and modified, provided that the effect of the invention is not compromised. In addition, the solenoid S in the solenoid valve V has a first movable iron core 43 and a second movable iron core 44, but is not limited to these, as long as it can generate a thrust for adjusting the opening pressure of the second valve core 15. Furthermore, in the solenoid valve V of this embodiment, when liquid flows from one side to the other through the flow path F, the pressure of the back pressure chamber P acting on the second valve core 15 is controlled by applying the thrust of the solenoid S to the control valve 21 to adjust the valve opening pressure. When liquid flows from the other side to one side through the flow path F, the pressure of the solenoid S acts on the second valve core 15 to adjust the valve opening pressure. However, the valve opening pressure can also be adjusted by applying the thrust of the solenoid S to the control valve 21 to control the pressure of the back pressure chamber P acting on the second valve core 15, regardless of the flow direction of the liquid through the flow path F. Alternatively, the valve opening pressure can be adjusted by applying the thrust of the solenoid S to the second valve core 15.

[0133] In addition, the first valve core 14 in the solenoid valve V of this embodiment is formed by an annular plate, so the axial length of the first valve core 14 is shortened, thus shortening the overall length of the solenoid valve V, improving the mounting performance on the buffer D, and the shape of the first valve core 14 is simplified, thus reducing manufacturing costs.

[0134] Furthermore, the buffer D of this embodiment includes: a cylinder (housing) 1; a piston rod 2 that is axially movable and inserted into the cylinder (housing) 1; a piston 3 that is connected to the piston rod 2 and is axially movable and inserted into the cylinder (housing) 1; and a solenoid valve V that is housed in the cylinder (housing) 1 and disposed between the extension side chamber (working chamber) R1 and the compression side chamber (working chamber) R2 disposed in the cylinder (housing) 1.

[0135] In the buffer D constructed in this manner, a solenoid valve V is provided as described above. Therefore, when a soft damping force is generated, the damping force will not be excessive and affect the ride comfort of the vehicle. In addition, as shown in the figure, the buffer D of this embodiment is set as a single-rod type buffer with the cylinder 1 as the outer shell. However, it can also be a multi-cylinder type buffer with an outer shell covering the outer periphery of the cylinder 1 and a liquid reservoir between the cylinder 1 and the outer shell. As long as the solenoid valve V can be accommodated in the outer shell, the compression side chamber R2 and the liquid reservoir can be arranged as working chambers between these working chambers, except between the extension side chamber R1 and the compression side chamber R2.

[0136] The preferred embodiments of the present invention have been described in detail above, but modifications, variations and alterations can be made without departing from the scope of the claims.

[0137] Symbol Explanation 1 cylinder (outer shell) 2 piston rods 3-piston 13 Valve seat components 13d annular valve seat 14 First valve core 15 Second valve core 15a Main body 15b flange portion 15c annular protrusion 15d valve orifice 15e control valve seat 15f Main Body Passage (Passage) 15g flange channel (channel) 21 Control Valve 22 Control Valve Body D buffer F flow path P back pressure chamber R1 elongated side chamber (working room) R2 compression side chamber (working chamber) S-Solenoid V-type solenoid valve

Claims

1. A solenoid valve, comprising: Valve seat component, having an annular valve seat surrounding the flow path; The annular first valve core is axially movable relative to the valve seat component and can be seated relative to the annular valve seat to open and close the flow path; The second valve core is axially movable relative to the valve seat component and the first valve core, stacked on the opposite side of the valve seat component of the first valve core, and can be seated relative to the first valve core to open and close the flow path; and The solenoid can apply a thrust to the second valve core, pushing it towards the valve seat component. The first valve core and the second valve core are subjected together to a force moving away from the valve seat component due to pressure on one side of the flow path, and are subjected to a force moving apart from each other due to pressure on the other side of the flow path. The second valve core has: a front-side pressure-receiving portion, which acts as a force away from the valve seat component when facing the valve seat component; and a rear-side pressure-receiving portion, which acts as a force approaching the valve seat component when facing the opposite side of the valve seat component. And channels that guide the pressure within the flow path to the pressure-bearing portion on the back side; The area of ​​the front-side pressure-bearing part is larger than the area of ​​the back-side pressure-bearing part.

2. The solenoid valve according to claim 1, wherein... The second valve core has a main body, a flange portion disposed on the outer periphery of the main body, and an annular protrusion protruding from the front side of the flange portion and abutting against the first valve core. The pressure-bearing portion on the back side includes the opposite end of the valve seat component of the main body and the opposite end of the valve seat component of the flange. The channel has a straight main body channel connecting the front side of the main body and the back side of the main body, and a straight flange channel that is the front side of the flange and connects the inner side of the annular protrusion and the back side of the flange.

3. The solenoid valve according to claim 2, comprising: A back pressure chamber directs the pressure from one side of the flow path to the back side of the flange; and The control valve receives thrust from the solenoid and adjusts the pressure in the back pressure chamber. The second valve core has a valve hole opening from the rear side of the main body and an annular control valve seat disposed on the rear side of the main body. The control valve has a control valve body that can be axially movable into the valve orifice and can be seated relative to the control valve seat. The solenoid applies a thrust to the second valve core when the control valve seat is seated on the control valve seat.

4. The solenoid valve according to claim 2, wherein... The main body channel and the flange channel are arranged parallel to the axis of the second valve core.

5. A buffer, comprising: shell; The piston rod is axially movable and inserted into the housing; A piston, connected to the piston rod, is axially movable and inserted into the housing; as well as The solenoid valve according to any one of claims 1 to 4 is housed within the housing and disposed between two working chambers disposed within the housing.

Images