Valve device

Abstract

A solenoid valve (1) comprises a sleeve (22), a spool (23), and a filter (31). The filter (31) has a first filter (32) and a second filter (33). The first filter (32) is wound around the outer peripheral surface of the sleeve (22) in a state in which a portion of the outer peripheral surface in the circumferential direction is exposed. The second filter (33) is wound around the outer peripheral side of the first filter (32), and both circumferential ends (33A, 33B) are affixed to the portion exposed by the first filter (32) on the outer peripheral surface of the sleeve (22).

Description

[Technical Field]

[0001] The present disclosure relates to a valve device incorporated in a hydraulic circuit of a construction machine such as a hydraulic excavator or a wheel loader. [Background technology]

[0002] In recent years, there has been an increasing demand for automated operation of construction machinery, such as hydraulic excavators, and the electronic control of construction machinery is being promoted. One known example of electronic control of construction machinery is a method of operating a control valve for controlling the actuators (hydraulic cylinders, hydraulic motors) of the construction machinery using hydraulic pressure controlled by a solenoid valve. Meanwhile, Patent Document 1 discloses a solenoid valve that advances or delays the valve timing of an engine. In the solenoid valve of Patent Document 1, the port of the sleeve (valve sleeve) is covered with a filter. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-22816 Summary of the Invention

[0004] The solenoid valve described in Patent Document 1 has one filter wound around the outer periphery of the sleeve at a position corresponding to the port. Alternatively, to ensure the strength of the filter or to improve the filtering performance of the filter, it is conceivable to wind multiple filters around the outer periphery of the sleeve. However, with a configuration in which multiple filters are wound one on top of the other, it is difficult to stably fix each filter.

[0005] An object of the present invention is to provide a valve device that allows a plurality of filters to be stably attached to a sleeve.

[0006] The present invention preferably provides a valve device comprising: a sleeve having a port and a valve element hole communicating with the port; a valve element inserted into the valve element hole of the sleeve and moving axially within the valve element hole; and a filter wrapped circumferentially around the outer periphery of the sleeve at a position corresponding to the port, wherein the filter comprises: a first filter wrapped around the outer periphery of the sleeve with a portion of the circumferential surface of the sleeve exposed, and both circumferential ends fixed to the outer periphery of the sleeve; and a second filter wrapped around the outer periphery of the first filter, and both circumferential ends fixed to portions of the outer periphery of the sleeve that are exposed from the first filter between the circumferential ends of the first filter.

[0007] According to the present invention, a plurality of filters can be stably attached to the sleeve. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a perspective view showing a valve device (solenoid valve) according to an embodiment. [Figure 2] FIG. 2 is a cross-sectional view showing the valve device in a state where it is assembled to a control valve. [Figure 3] FIG. 2 is a partial cross-sectional view showing a valve portion of the valve device. [Figure 4] FIG. 4 is an enlarged cross-sectional view of part (IV) in FIG. [Figure 5] FIG. 2 is a front view showing a sleeve to which a first filter is fixed. [Figure 6] FIG. 2 is a front view showing a sleeve to which a first filter and a second filter are fixed. [Figure 7] 7 is a cross-sectional view of the first filter, the sleeve, the spool, etc., as viewed from the direction of arrows VII-VI in FIG. 5. [Figure 8] 8 is a cross-sectional view of the first filter, the second filter, the sleeve, the spool, etc., as viewed from the direction of arrows VIII-VIII in FIG. 6. [Figure 9] FIG. 2 is an explanatory diagram showing a first filter and a second filter in an expanded state. [Figure 10]9 is a cross-sectional view taken in the same position as FIG. 8 and showing a first filter, a second filter, a sleeve, a spool, etc. according to a first modified example. [Figure 11] FIG. 5 is a cross-sectional view of a filter according to a second modified example taken from the same position as in FIG. 4. [Figure 12] FIG. 10 is a half cross-sectional view showing a valve device (relief valve) according to a third modified example. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, a valve device according to an embodiment will be described in detail with reference to the accompanying drawings, taking as an example a case where the valve device is applied to a solenoid valve incorporated in a hydraulic circuit of a construction machine.

[0010] 1 to 9 show an embodiment. In FIGS. 1 and 2, a solenoid valve 1 serving as a valve device is configured as a solenoid valve. The solenoid valve 1 opens and closes a flow path when a plunger 9 of a solenoid unit 2 drives a spool 23 of a valve unit 21 in the axial direction. The solenoid valve 1 is assembled to a control port of a device that controls the flow and pressure of a control fluid (e.g., hydraulic oil). For example, as shown in FIG. 2, the solenoid valve 1 is assembled to a control valve 41 of a hydraulic excavator (not shown), which is a representative example of construction machinery. In this case, the solenoid valve 1 is attached to a housing 42 of the control valve 41, for example.

[0011] The control valve 41 of the hydraulic excavator is a control valve group (control valve device) consisting of multiple directional control valves. The control valve 41 of the hydraulic excavator distributes pressure oil discharged from a hydraulic pump (not shown) to multiple hydraulic actuators (hydraulic cylinders, hydraulic motors) such as a boom cylinder, arm cylinder, bucket cylinder, traveling hydraulic motor, and swing hydraulic motor (none of which are shown) in response to the operation of the travel lever / pedal and work lever (neither of which are shown) operated by the operator. The solenoid valve 1 opens and closes the flow path based on the supply of power from a control device (not shown) that controls the solenoid valve 1. This allows the solenoid valve 1 to control the pilot pressure oil that displaces (moves) the spool (not shown) of the control valve 41.

[0012] 1 to 3, the solenoid valve 1 includes a solenoid unit 2 as an actuator, and a valve unit 21 driven by the solenoid unit 2. The solenoid valve 1 is configured as a three-port, two-position pressure control valve (proportional solenoid valve) in which the valve unit 21 is switched by the solenoid unit 2. The solenoid unit 2 and the valve unit 21 are arranged coaxially.

[0013] First, the solenoid unit 2 will be described. As shown in FIG. 2, the solenoid unit 2 includes a coil 3, a housing 4 as a stator, an anchor 5, a yoke 6, a contact member 7, a connecting member 8, a plunger 9 as a mover, an operating pin 10, a spring 11, and a socket 12. The coil 3 is formed by winding a conductive wire in a circular shape. The coil 3 generates a magnetic force when power is supplied (energized) from an external source. The housing 4 is formed in a cylindrical shape with a bottom. The housing 4 is disposed on the inner periphery of the coil 3. The housing 4 extends in the axial direction of the coil 3, and is open at one end in the axial direction (the right end in FIG. 2). A connecting member 8 is fixed to one end of the housing 4.

[0014] The anchor 5 is formed in a cylindrical shape with both axial ends open. The anchor 5 is provided on one side (the right end in FIG. 2) in the movement direction of the plunger 9. The sleeve 22 of the valve portion 21 is attached to one axial end (the right end in FIG. 2) of the anchor 5. That is, a female thread 5A is formed on the inner periphery of one end of the anchor 5. The male thread 22N of the sleeve 22 is screwed into the female thread 5A of the anchor 5. Meanwhile, the other end (the left end in FIG. 2) of the anchor 5 extends axially along the inner periphery of the coil 3 toward the housing 4. The connecting member 8 is fixed to the other end (the left end in FIG. 2) of the anchor 5.

[0015] The yoke 6 is formed in a cylindrical shape with both axial ends open. The yoke 6 is disposed radially outward of the housing 4 and the anchor 5. One axial end (the right end in FIG. 2 ) of the yoke 6 is attached to the housing 42 of the control valve 41. That is, a male thread 6A is formed on the outer periphery of the one end of the yoke 6. The male thread 6A of the yoke 6 is threadedly engaged with the female thread 42E of a control port portion 42A provided in the housing 42 of the control valve 41. The yoke 6 is fitted onto the inner periphery of the one end of the yoke 6. That is, the inner circumferential surface of the one end of the yoke 6 and the outer circumferential surface of the one end of the anchor 5 abut against each other.

[0016] Meanwhile, the other end side (the left end side in FIG. 2 ) of the yoke 6 extends axially toward the socket 12 on the outer periphery side of the coil 3. The yoke 6 is a magnetic member that, together with the housing 4, forms a magnetic circuit (magnetic path) between the inner and outer peripheries of the coil 3. In this case, an abutting member 7 is disposed on the other end side of the yoke 6, positioned between the inner periphery of the yoke 6 and the outer periphery of the housing 4 and constituting a magnetic circuit between the yoke 6 and the housing 4. The inner periphery of the abutting member 7 abuts against the outer periphery of the housing 4 over the entire periphery, and a portion of the outer periphery of the abutting member 7 in the circumferential direction abuts against the inner periphery of the yoke 6. This allows magnetic flux to be transferred between the yoke 6 and the housing 4.

[0017] The connecting member 8 is formed in a cylindrical shape with both axial ends open. The connecting member 8 is made of a non-magnetic material. One axial end (the right side in FIG. 2 ) of the connecting member 8 is fixed to the anchor 5, and the other axial end (the left side in FIG. 2 ) is fixed to the housing 4. The plunger 9 is formed in a cylindrical shape with both axial ends open. The plunger 9 is provided so as to be movable in the axial direction of the coil 3. That is, the plunger 9 is disposed inside the housing 4 and is movable in the axial direction between the housing 4 and the anchor 5. The actuating pin 10 is fixed to the plunger 9. The actuating pin 10 moves integrally with the plunger 9. The actuating pin 10 transmits the thrust of the plunger 9 to the spool 23 of the valve portion 21.

[0018] The spring 11 is provided between the bottom of the housing 4 and the plunger 9. The spring 11 presses the operating pin 10 toward the spool 23 via the plunger 9 so that one end (the right end in FIG. 2) of the operating pin 10 does not separate from the other end (the left end in FIG. 2) of the spool 23. A cable (not shown) that supplies power to the coil 3 of the solenoid unit 2 is connected to the socket 12. When power is supplied, the coil 3 magnetizes or demagnetizes the anchor 5, causing the plunger 9 to move toward or away from the anchor 5. As a result, the spool 23 of the valve unit 21 is driven axially by the solenoid unit 2 (plunger 9).

[0019] Next, the valve portion 21 will be described. As shown in Figures 2 and 3, the valve portion 21 includes a sleeve 22 that serves as a valve sleeve, a spool 23 that serves as a valve body, and a return spring 24. As shown in Figure 2, the valve portion 21 is attached to a housing 42 of a control valve 41 together with the solenoid portion 2. That is, the housing 42 of the control valve 41 is provided with a control port portion 42A to which the solenoid valve 1 is attached. The control port portion 42A is provided with a female thread 42E located on the opening side.

[0020] The valve portion 21 is inserted into the control port portion 42A. The valve portion 21 and the solenoid portion 2 are fixed to the housing 42 of the control valve 41 by threading the male thread 6A of the solenoid portion 2 into the female thread 42E of the control port portion 42A. That is, the solenoid valve 1 is fixed to the housing 42 of the control valve 41 by threading the male thread 6A of the solenoid portion 2 into the female thread 42E of the control port portion 42A. A seal ring 43 (O-ring) is provided between the inner circumferential surface of the control port portion 42A and the outer circumferential surface of the valve portion 21 to seal the gap therebetween.

[0021] As shown in Figures 2 and 3, the sleeve 22 is formed in a cylindrical shape with a bottom. That is, the sleeve 22 is provided with a slide hole 22A as a valve body hole into which the spool 23 is slidably inserted. The sleeve 22 has a large-diameter cylindrical portion 22B located on one axial side (the right side in Figures 2 and 3), a small-diameter cylindrical portion 22C located on the other axial side (the left side in Figures 2 and 3), and a bottom portion 22D that closes one end of the large-diameter cylindrical portion 22B. As a result, the sleeve 22 is formed in a stepped cylindrical shape with a bottom and extends in the axial direction. The end (one end) of the sleeve 22 opposite the solenoid portion 2 is closed by the bottom portion 22D.

[0022] The large-diameter cylindrical portion 22B is provided with a pump port 22E, a tank port 22F, and an actuator port 22G through which the control fluid passes. The pump port 22E, which serves as a supply port, is formed in the large-diameter cylindrical portion 22B as an oil passage extending in the radial direction of the large-diameter cylindrical portion 22B. One side of the pump port 22E opens to the outer diameter side of the large-diameter cylindrical portion 22B, and the other side opens to the slide hole 22A. One opening of the pump port 22E opens to an annular recess 22H provided on the outer circumferential surface of the large-diameter cylindrical portion 22B.

[0023] The annular recess 22H is formed on the outer peripheral surface of the large-diameter cylindrical portion 22B as a full-circumferential recessed groove whose outer diameter is smaller than that of adjacent portions in the axial direction. The pump port 22E is connected to a hydraulic pump (not shown), for example, a pilot pump of a hydraulic excavator, via a pump oil passage 42B provided in the housing 42 of the control valve 41. As will be described later, a filter 31 is provided in the annular recess 22H where the pump port 22E opens, so as to cover the opening of the pump port 22E.

[0024] A tank port 22F, which serves as a drain port, is also formed in the large-diameter cylindrical portion 22B as an oil passage extending radially of the large-diameter cylindrical portion 22B. The tank port 22F is located closer to the small-diameter cylindrical portion 22C than the pump port 22E. One side of the tank port 22F opens to the outer diameter side of the large-diameter cylindrical portion 22B, and the other side opens to the slide hole 22A. One opening of the tank port 22F opens to an annular recess 22J provided on the outer circumferential surface of the large-diameter cylindrical portion 22B.

[0025] The annular recess 22J is formed on the outer peripheral surface of the large-diameter cylindrical portion 22B as a full-circumferential recessed groove whose outer diameter dimension is smaller than that of an axially adjacent portion. The tank port 22F is connected to a tank (not shown), for example, a hydraulic oil tank of a hydraulic excavator, via a tank oil passage 42C provided in the housing 42 of the control valve 41.

[0026] The actuator port 22G, which serves as an output port, is formed in the large-diameter cylindrical portion 22B as an oil passage extending in the axial direction of the large-diameter cylindrical portion 22B. One side of the actuator port 22G opens to the bottom portion 22D, and the other side opens to the slide hole 22A. The opening on the other side of the actuator port 22G opens to an annular recess 22K provided on the inner circumferential surface of the slide hole 22A. The annular recess 22K is formed in the slide hole 22A as a circumferential groove whose inner diameter is larger than that of adjacent portions in the axial direction.

[0027] The annular recess 22K is located between the pump port 22E and the tank port 22F. The actuator port 22G is connected to a hydraulic actuator (not shown), for example, a hydraulic pilot chamber of a control valve (directional control valve) of a hydraulic excavator, via an actuator oil passage 42D provided in the housing 42 of the control valve 41.

[0028] Furthermore, seal grooves 22L and 22M, which are full-circumferential grooves, are provided at two locations on the outer circumferential surface of large-diameter cylindrical portion 22B. That is, a tip-side seal groove 22L, into which a tip-side seal ring 44 (O-ring) is attached, is provided on the tip side (bottom 22D side) of large-diameter cylindrical portion 22B. A base-side seal groove 22M, into which a base-side seal ring 45 (O-ring) is attached, is provided on the base-end side (small-diameter cylindrical portion 22C side) of large-diameter cylindrical portion 22B between pump port 22E and tank port 22F.

[0029] The distal seal ring 44 seals between the actuator port 22G (actuator oil passage 42D) and the pump port 22E (pump oil passage 42B). The proximal seal ring 45 seals between the pump port 22E (pump oil passage 42B) and the tank port 22F (tank oil passage 42C).

[0030] The small diameter cylindrical portion 22C of the sleeve 22 is fixed to the anchor 5 of the solenoid portion 2. That is, a male thread 22N is formed on the outer periphery of the small diameter cylindrical portion 22C. The male thread 22N of the small diameter cylindrical portion 22C is screwed into the female thread 5A provided on the anchor 5 of the solenoid portion 2. This allows the valve portion 21 and the solenoid portion 2 to be connected together as a single unit with the spool 23 inserted into the sleeve 22.

[0031] The spool 23 is provided in a sliding hole 22A of the sleeve 22. The spool 23 is capable of moving in the axial direction within the sliding hole 22A. The spool 23 is formed as a long rod-like body, and extends in the axial direction on the inner circumferential side of the sleeve 22. An axial flow passage 23A extending in the axial direction is formed at the axial center position of the spool 23.

[0032] A flange portion 23B that protrudes radially outward over the entire circumference is provided on the other axial end side (the left end side in FIGS. 2 and 3) of the spool 23. The flange portion 23B faces the end face (opening end face) of the small-diameter cylindrical portion 22C of the sleeve 22. A return spring 24 is provided between the flange portion 23B of the spool 23 and the small-diameter cylindrical portion 22C of the sleeve 22.

[0033] The spool 23 is pressed against the anchor 5 of the solenoid unit 2 by the biasing force of the return spring 24. For example, when the solenoid unit 2 is in a de-energized state in which power is not supplied to the coil 3, the biasing force of the return spring 24 causes the other end face of the spool 23 to abut against the end face of the anchor 5. In this state, one end face of the operating pin 10 is abutted against the other end face of the spool 23 by the spring 11 of the solenoid unit 2. In other words, even when the solenoid unit 2 is in a de-energized state, the abutment between the other end face of the spool 23 and one end face of the operating pin 10 is maintained by the spring 11 of the solenoid unit 2.

[0034] Lands 23C and 23D are provided on the outer peripheral surface of the spool 23 and spaced apart in the axial direction. When the other end (other end face) of the spool 23 abuts against the anchor 5 of the solenoid unit 2 (de-energized state), the pump port 22E and the actuator port 22G are blocked by the land 23C, and the actuator port 22G and the tank port 22F are communicated with each other via the small diameter portion 23E between the lands 23C and 23D. In this case, the pressure oil in the actuator oil passage 42D is guided to the tank oil passage 42C via the actuator port 22G and the tank port 22F and returns to a tank (hydraulic oil tank) not shown.

[0035] In contrast, when power is supplied to the coil 3 of the solenoid unit 2, the spool 23 moves axially to one side (the right side in FIGS. 2 and 3) via the plunger 9 and the operating pin 10 against the biasing force of the return spring 24. At this time, that is, with the spool 23 moved axially to one side, the pump port 22E and the actuator port 22G communicate with each other via the small diameter portion 23E between the lands 23C and 23D, and the actuator port 22G and the tank port 22F are blocked by the land 23D. In this case, the pressure oil in the pump oil passage 42B is guided to the actuator oil passage 42D via the pump port 22E and the actuator port 22G and supplied to a hydraulic actuator (hydraulic pilot chamber of a control valve) not shown.

[0036] The spool 23 is provided with radial passages 23F and 23G that penetrate radially and are spaced apart in the axial direction. Each of these radial passages 23F and 23G is connected to the axial passage 23A. As a result, the tank (hydraulic oil tank) is connected to the inner circumferential side of the anchor 5 of the solenoid unit 2 via the tank port 22F, the radial passage 23F, the axial passage 23A, and the radial passage 23G. Furthermore, the inner circumferential side of the anchor 5 is connected to the inside of the plunger 9 through a passage 10A provided in the actuating pin 10 and between the inner periphery of the anchor 5 and the outer periphery of the actuating pin 10. In this way, the interior of the solenoid unit 2 is connected to the tank via the valve unit 21 (the interior of the spool 23).

[0037] The solenoid valve described in the aforementioned Patent Document 1 has one filter wrapped around the outer periphery of the sleeve at a position corresponding to the port. Alternatively, to ensure the filter's strength against deformation or to improve its filtering performance, it is possible to wrap multiple filters around the outer periphery of the sleeve. However, simply wrapping the filter two or three times may result in an unstable attachment of the filter to the sleeve. In particular, when filters with different mesh sizes are attached to the sleeve by, for example, welding or adhesive, the overlap between the filters may differ depending on the attachment location, making the attachment unstable.

[0038] In contrast, in the embodiment, the filter 31 is configured with two filters 32, 33, namely, a first filter 32 located radially inside and a second filter 33 located radially outside. In this case, as shown in Fig. 7, the first filter 32 is wound around the outer periphery of the sleeve 22 in a segmented ring shape (C-shape). That is, as shown in Fig. 5, the first filter 32 is wound around the outer periphery of the sleeve 22 in a state where a circumferential portion of the outer periphery of the sleeve 22 is exposed.

[0039] More specifically, the first filter 32 is wound around the outer circumferential surface of the sleeve 22 (the bottom surface of the annular recess 22H) so that both circumferential ends 32A, 32B face each other and are spaced apart from each other in the circumferential direction. As a result, the outer circumferential surface of the sleeve 22 is exposed from the first filter 32 between the one end 32A and the other end 32B in the circumferential direction of the first filter 32.

[0040] 6 and 8, the second filter 33 is wound around the outer periphery of the first filter 32 radially outward of the first filter 32 in an annular (O-shaped) configuration. The second filter 33 may also be wound in a segmented annular (C-shaped) configuration, as in a first modified example shown in FIG. 10 (described later). In either case, both circumferential ends 33A and 33B of the second filter 33 are fixed to a portion of the outer circumferential surface of the sleeve 22 that is exposed from the first filter 32 between the circumferential ends 32A and 32B of the first filter 32 (a portion not covered by the first filter 32). This allows both the first filter 32 and the second filter 33 to be stably fixed to the outer circumferential surface of the sleeve 22 in this embodiment. This point will be described in detail below.

[0041] First, in this embodiment, solenoid valve 1 as a valve device includes sleeve 22, spool 23 as a valve element, and filter 31. Sleeve 22 is provided with ports 22E, 22F, and 22G, and slide hole 22A as a valve element hole communicating with ports 22E, 22F, and 22G. Spool 23 is inserted into slide hole 22A of sleeve 22. Spool 23 moves in the axial direction within slide hole 22A. In this case, spool 23 is displaced relative to sleeve 22 by solenoid unit 2 as an actuator driven by supply of electric power.

[0042] The filter 31 is provided on the outer circumferential side of the sleeve 22 at a position corresponding to the pump port 22E. In this case, the filter 31 is provided in the annular recess 22H into which the pump port 22E opens. The filter 31 is wound around the sleeve 22 in the circumferential direction within the annular recess 22H. In this embodiment, the filter 31 includes a first filter 32 and a second filter 33.

[0043] The first filter 32 is wrapped around the outer peripheral surface of the sleeve 22 (the bottom surface of the annular recess 22H) with a circumferential portion of the outer peripheral surface exposed. That is, when the first filter 32 is wrapped around the outer peripheral surface of the sleeve 22, both circumferential ends 32A, 32B of the first filter 32 face each other and are spaced apart from each other in the circumferential direction. The both circumferential ends 32A, 32B of the first filter 32 are fixed to the outer peripheral surface of the sleeve 22.

[0044] As a result, while the first filter 32 is fixed to the outer peripheral surface of the sleeve 22, the portion of the outer peripheral surface of the sleeve 22 between one end 32A and the other end 32B in the circumferential direction of the first filter 32 is exposed. In other words, the one end 32A and the other end 32B in the circumferential direction of the first filter 32 do not overlap in the radial direction on the outer peripheral surface of the sleeve 22. Therefore, as shown in Fig. 7, the cross section of the first filter 32 has a segmented ring shape (C-shape).

[0045] 6 and 8, the second filter 33 is wound around the outer circumferential side of the first filter 32. In this case, as shown in Fig. 6 and 8, both circumferential ends 33A, 33B of the second filter 33 are fixed to the outer circumferential surface of the sleeve 22 between both circumferential ends 32A, 32B of the first filter 32. As a result, both circumferential ends 33A, 33B of the second filter 33 are fixed to portions of the outer circumferential surface of the sleeve 22 that are exposed from the first filter 32.

[0046] In this case, the second filter 33 is wound around the entire outer periphery of the outer periphery of the sleeve 22 radially outside the first filter 32. That is, the second filter 33 is wound in an annular (O-shaped) shape around the outer periphery of the first filter 32. In other words, one end 33A and the other end 33B in the circumferential direction of the second filter 33 overlap in the radial direction on the outer periphery of the sleeve 22. As a result, as shown in FIG. 8 , the second filter 33 has an annular (O-shaped) cross-sectional shape.

[0047] The first filter 32 and the second filter 33 are fixed to the outer peripheral surface of the sleeve 22 by welding. That is, one circumferential end 32A of the first filter 32 is fixed to the outer peripheral surface of the sleeve 22 (the bottom surface of the annular recess 22H) by spot welding 34. The other circumferential end 32B of the first filter 32 is fixed to the outer peripheral surface of the sleeve 22 (the bottom surface of the annular recess 22H) by spot welding 35, in a state where it is circumferentially spaced from the one end 32A (in other words, in a state where it faces the one end 32A with a circumferential gap therebetween). The second filter 33 is fixed to the outer peripheral surface of the sleeve 22 (the bottom surface of the annular recess 22H) by spot welding 36, in a state where both ends 33A, 33B overlap radially. The spot welds 34, 35, and 36 correspond to the fixed portions of the filter 31 (the first filter 32 and the second filter 33).

[0048] 9 shows the first filter 32 and the second filter 33 in an unfolded state, i.e., before being wrapped around the outer peripheral surface (the bottom surface of the annular recess 22H) of the sleeve 22. As shown in Fig. 9, the length L1 of the first filter 32 is shorter than the length L2 of the second filter 33. The length L1 of the first filter 32 is shorter than the circumferential length of the outer peripheral surface of the sleeve 22, more specifically, the length of the outer periphery of the annular recess 22H.

[0049] Therefore, when the first filter 32 is wound inside the annular recess 22H, both circumferential ends 32A, 32B of the first filter 32 face each other with a gap in the circumferential direction. In contrast, the length dimension L2 of the second filter 33 is longer than the circumferential length of the outer circumferential surface of the sleeve 22, more specifically, the outer periphery length of the annular recess 22H. Therefore, when the second filter 33 is wound inside the annular recess 22H, both circumferential ends 33A, 33B of the second filter 33 overlap each other in the radial direction.

[0050] Furthermore, the first filter 32 and the second filter 33 are configured as mesh filters. In this case, the first filter 32 has a coarser mesh than the second filter 33 and is more resistant to deformation. Conversely, the second filter 33 has a finer mesh than the first filter 32 and is less resistant to deformation. Here, the mesh size (e.g., filtering performance, filtering accuracy) of the second filter 33 is set according to the size of the particles (contaminants) to be captured in the hydraulic oil, pressure loss, etc. Compared to this second filter 33, the first filter 32 has a coarser mesh.

[0051] That is, the first filter 32 has lower filtering performance (filtration accuracy) and smaller pressure loss than the second filter 33. For example, if the particle size of the particles (contaminants) captured by the second filter 33 is 1, the particle size of the particles (contaminants) captured by the first filter 32 is 2 to 5 (more preferably, 4 to 5). Also, for example, if the pressure loss of the second filter 33 is 1, the pressure loss of the first filter 32 is 0.2 to 0.4 (more preferably, 0.25 or less).

[0052] The strength of the first filter 32 can be set so as to ensure the necessary strength for both the first filter 32 and the second filter 33. In this case, when the strength of the second filter 33 is 1, the strength of the first filter 32 is set to 15 to 25 (more preferably, 20 or more). Furthermore, the thickness of the filter material (component) of the first filter 32 can be greater than the thickness of the filter material (component) of the second filter 33. In this case, when the thickness of the filter material of the second filter 33 is 1, the thickness of the filter material of the first filter 32 is set to 2 to 5 (more preferably, 2.5 or more). Furthermore, the first filter 32 may use a filter material made of a different material from that of the second filter 33.

[0053] As a result, in this embodiment, the first filter 32 serves as a reinforcing filter that reinforces the second filter 33 on the inner diameter side of the second filter 33. In contrast, the second filter 33 serves as a filtering filter that prevents foreign matter in the hydraulic oil from passing through on the radially outer side of the first filter 32, which serves as a reinforcing filter. That is, the hydraulic oil (control fluid) flows from the pump oil passage 42B side to the pump port 22E in which the first filter 32 and the second filter 33 are provided.

[0054] As a result, the pressure upstream of the second filter 33 is higher than the pressure downstream of the first filter 32, and the difference between these pressures (differential pressure) generates a pushing force from the second filter 33 toward the first filter 32. Because the second filter 33 is made of a fine mesh filter (filter material), the force resulting from the differential pressure can cause the second filter 33 to deform excessively, resulting in a decrease in filtering performance or even damage. In contrast, the first filter 32 has greater resistance to deformation than the second filter 33. Therefore, the first filter 32 can suppress deformation of the second filter 33 and prevent damage to the second filter 33. This allows the second filter 33 to be installed in a stable state while maintaining its filtering performance.

[0055] The solenoid valve 1 according to the embodiment has the configuration described above, and the operation of the solenoid valve 1 will be described below.

[0056] First, the solenoid valve 1 is connected to a control device (not shown) that controls the solenoid valve 1. That is, a plug (not shown) of a cable extending from the control device is connected to the socket 12 of the solenoid valve 1. When power is not supplied to the coil 3 of the solenoid unit 2, the spool 23 of the valve unit 21 is urged toward the solenoid unit 2 by the return spring 24, and the other end face of the spool 23 abuts against one end face of the solenoid unit 2 (anchor 5). As a result, the pump port 22E and the actuator port 22G of the sleeve 22 are blocked, and the actuator port 22G and the tank port 22F are maintained in a state in which they are communicated (initial state).

[0057] When power is supplied from the control device to the coil 3, a magnetic field (excitation force) is generated by the coil 3, and the plunger 9 is attracted to the anchor 5 with an attractive force corresponding to the value of the current supplied to the coil 3. At this time, the plunger 9 moves toward the anchor 5 within the housing 4. The plunger 9 then stops at a position where the hydraulic force acting on the spool 23, the spring force of the return spring 24, and the attractive force of the anchor 5 are balanced.

[0058] This displacement of the plunger 9 is transmitted to the spool 23 via the actuation pin 10, causing the spool 23 to move within the slide hole 22A of the sleeve 22. As a result, the pump port 22E of the sleeve 22 communicates with the actuator port 22G, and the actuator port 22G is blocked from the tank port 22F.

[0059] As a result, pressure oil is supplied to a hydraulic actuator (for example, a hydraulic pilot chamber of a directional control valve) via the solenoid valve 1. At this time, hydraulic oil that has passed through filters 31 (first filter 32 and second filter 33) flows from the radial outside to the inside of the sleeve 22 into the pump port 22E. When power supply to the coil 3 is stopped, the magnetic field generated by the coil 3 disappears, and the spring force of the return spring 24 returns the spool 23 to its initial state.

[0060] In the embodiment, the second filter 33, which is wound around the outer circumferential side of the first filter 32, has both circumferential ends 33A, 33B fixed to the outer circumferential surface of the sleeve 22 (the bottom surface of the annular recess 22H). In this case, the both circumferential ends 33A, 33B of the second filter 33 are fixed between the both circumferential ends 32A, 32B of the first filter 32, i.e., to a portion of the outer circumferential surface of the sleeve 22 that is exposed from the first filter 32. Therefore, in addition to being able to stably fix the first filter 32 to the outer circumferential surface of the sleeve 22, the second filter 33 can also be stably fixed to the outer circumferential surface of the sleeve 22.

[0061] This allows the two filters 32, 33 to be stably attached to the sleeve 22. That is, in this embodiment, the two filters 32, 33, which have different mesh sizes, can be fixed to the outer peripheral surface of the sleeve 22 at locations where these filters 32, 33 do not overlap. Therefore, the two filters 32, 33 can be stably attached to the outer peripheral surface of the sleeve 22.

[0062] According to the embodiment, the second filter 33 is wound around the entire outer peripheral surface of the sleeve 22 in an annular (O-shaped) shape. Therefore, both ends 33A, 33B of the second filter 33 in the circumferential direction can be collectively fixed to the outer peripheral surface of the sleeve 22. This reduces the effort (procedure) required for fixing the second filter 33 compared to fixing both ends 33A, 33B of the second filter 33 in the circumferential direction separately.

[0063] In particular, according to the embodiment, the second filter 33 has a component (filter material) that is sufficiently fine and has a finer mesh than the first filter 32. Therefore, even when both ends 33A, 33B of the second filter 33 are overlapped and fixed to the outer peripheral surface of the sleeve 22 by spot welding, the second filter 33 can be stably fixed to the outer peripheral surface of the sleeve 22.

[0064] According to the embodiment, the first filter 32 has a coarser mesh and is stronger than the second filter 33. Therefore, when liquid flows into the pump port 22E from the outside to the inside in the radial direction of the sleeve 22, the first filter 32 located on the inner diameter side can prevent the second filter 33 located on the outer diameter side from being deformed. This makes it possible to prevent damage to the second filter 33 while ensuring the filtering performance of the second filter 33.

[0065] According to the embodiment, the first filter 32 and the second filter 33 are fixed by welding to the outer peripheral surface of the sleeve 22. Therefore, the first filter 32 and the second filter 33 can be stably fixed to the outer peripheral surface of the sleeve 22 by welding.

[0066] According to the embodiment, the valve element of the solenoid valve 1 (valve portion 21) that serves as the valve device is the spool 23. Therefore, in a valve device (spool valve) that uses the spool 23 as the valve element, multiple filters 32, 33 can be stably attached to the sleeve 22.

[0067] According to the embodiment, the spool 23 serving as a valve element is displaced relative to the sleeve 22 by an actuator (solenoid unit 2) that is driven by a supply of electric power. Therefore, a valve device (solenoid valve, electromagnetic valve, motor-operated valve) that includes an actuator (solenoid) that is driven by a supply of electric power can stably attach multiple filters 32, 33 to the sleeve 22.

[0068] In the embodiment, the first filter 32 has a coarser mesh than the second filter 33 and is more resistant to deformation. However, this is not limiting. For example, the second filter may have a coarser mesh than the first filter and be more resistant to deformation. That is, the relationship (characteristics) between the mesh size (e.g., filtering performance, filtering accuracy), strength, and thickness of the filter material (component) of the first and second filters may be reversed from that of the embodiment. In this case, the first filter and the second filter may be provided in the annular recess 22J into which the tank port 22F opens, so as to cover the opening of the tank port 22F.

[0069] That is, the second filter serves as a reinforcing filter that reinforces the first filter on the outer diameter side of the first filter. The first filter serves as a filtering filter that prevents foreign matter in the hydraulic oil from passing through on the radially inner side of the second filter, which serves as a reinforcing filter. This allows the second filter to prevent the first filter from deforming toward the outer diameter side when hydraulic oil flows from the tank port 22F from the radially inner side toward the outer side of the sleeve 22.

[0070] In this way, if the second filter has a coarser mesh and is stronger than the first filter, the second filter located on the outer diameter side can prevent the first filter located on the inner diameter side from being deformed when liquid flows out of the port from the inner side to the outer side in the radial direction of the sleeve, thereby ensuring the filtering performance of the first filter and preventing damage to the first filter.

[0071] In the embodiment, the second filter 33 is wound around the entire outer periphery of the outer periphery of the sleeve 22 (the bottom surface of the annular recess 22H) in an annular (O-shaped) shape. However, the present invention is not limited to this, and the second filter 33 may be wound around the outer periphery of the sleeve 22 in a segmented annular (C-shaped) shape, as in a first modified example shown in FIG.

[0072] That is, the second filter 33 may be wrapped around the outer peripheral surface of the sleeve 22 (the bottom surface of the annular recess 22H) with a circumferential portion of the outer peripheral surface exposed. In this case, when the second filter 33 is wrapped around the outer peripheral side of the first filter 32, both circumferential ends 33A, 33B face each other and are spaced apart in the circumferential direction. As a result, the outer peripheral surface of the sleeve 22 is exposed between one end 33A and the other end 33B of the second filter 33 in the circumferential direction.

[0073] According to the first modified example, the second filter 33 is wound around the outer peripheral surface of the sleeve 22 (the bottom surface of the annular recess 22H) in a state where a portion of the outer peripheral surface is exposed in the circumferential direction. Therefore, when a third filter is further wound around the outer peripheral side of the second filter 33, the third filter can also be stably fixed to the outer peripheral surface of the sleeve 22.

[0074] 11, the filter 31 includes a third filter 37 in addition to the first filter 32 and the second filter 33. In this case, the second filter 33 is wound around the outer peripheral surface of the sleeve 22 in a state where a circumferential portion of the outer peripheral surface is exposed, as in the first modified example shown in FIG. 10. In addition, the third filter 37 is wound around the outer peripheral side of the second filter 33.

[0075] The third filter 37 has both circumferential ends (not shown) fixed to portions of the outer circumferential surface of the sleeve 22 that are exposed from the first filter 32 and the second filter 33. The third filter 37 may be wrapped around the entire outer circumferential surface of the sleeve 22 in an annular (O-shaped) shape. The third filter 37 may also be wrapped around the outer circumferential surface of the sleeve 22 in a state where a circumferential portion of the outer circumferential surface is exposed (a partial annular or C-shaped shape).

[0076] In this case, first filter 32 and third filter 37 can be filters that are coarser and more resistant to deformation than second filter 33. For example, if the particle size of particles (contaminants) captured by second filter 33 is 1, the particle size of particles (contaminants) captured by first filter 32 and third filter 37 can be 2 to 5 (more preferably, 4 to 5). For example, if the pressure loss of second filter 33 is 1, the pressure loss of first filter 32 and third filter 37 can be 0.2 to 0.4 (more preferably, 0.25 or less).

[0077] For example, if the strength of second filter 33 is 1, the strengths of first filter 32 and third filter 37 can be 15 to 25 (more preferably, 20 or more). For example, if the thickness of the filter material of second filter 33 is 1, the thickness of the filter material of first filter 32 and third filter 37 can be 2 to 5 (more preferably, 2.5 or more).

[0078] According to the second modified example, the third filter 37, which is wound around the outer peripheries of the first filter 32 and the second filter 33, can have both circumferential ends fixed to the outer circumferential surface (the bottom surface of the annular recess 22H) of the sleeve 22. In this case, both circumferential ends of the third filter 37 can be fixed between both circumferential ends 33A, 33B of the second filter 33 shown in FIG. 10 , i.e., to portions of the outer circumferential surface of the sleeve 22 that are exposed from the first filter 32 and the second filter 33.

[0079] Therefore, in addition to being able to stably fix the first filter 32 and the second filter 33 to the outer peripheral surface of the sleeve 22, the third filter 37 can also be stably fixed to the outer peripheral surface of the sleeve 22. This allows the three filters 32, 33, 37 to be stably attached to the sleeve 22.

[0080] Furthermore, according to the second modification, the first filter 32 and the third filter 37 have coarser meshes and greater strength than the second filter 33. Therefore, when liquid flows into the port 22E from the outside to the inside in the radial direction of the sleeve 22, the first filter 32, which is located on the innermost side, can prevent the second filter 33 from deforming. Furthermore, when liquid flows out of the port 22E from the inside to the outside in the radial direction of the sleeve 22, the third filter 37, which is located on the outermost side, can prevent the second filter 33 from deforming. This ensures the filtering performance of the second filter 33 while preventing damage to the second filter 33, regardless of the flow direction of the liquid in the port 22E.

[0081] 11, the case where port 22E is covered with three filters 32, 33, and 37 has been described as an example. However, this is not limiting, and four or more filters may be used. In such a case, the outer filter positioned at the outermost radial position can be fixed to the outer peripheral surface of the sleeve, and the remaining filters positioned inside this outer filter can be wound around the outer periphery of the sleeve in a segmented ring shape (C-shape).

[0082] In the second modified example shown in FIG. 11 , the first filter 32 and the third filter 37 have a coarser mesh and higher strength than the second filter 33. However, this is not limiting. For example, the first filter may have a coarser mesh and higher strength than the second and third filters. The third filter may have a coarser mesh and higher strength than the second and first filters. That is, the characteristics of each filter wound around the sleeve, such as mesh size, strength, thickness, and material, can be set to ensure the required filtration performance, pressure loss, strength, and the like. The same applies to a case where four or more filters are used.

[0083] In the embodiment, an example has been described in which the valve element of the solenoid valve 1, which is the valve device, is the spool 23. Also, in the embodiment, an example has been described in which the valve device is the solenoid valve 1 in which the spool 23, which is the valve element, is displaced relative to the sleeve 22 by a solenoid unit 2 (actuator) that is driven by a supply of power. However, the present invention is not limited to this, and the valve device may be a relief valve 51, for example, as in a third modified example shown in Fig. 12. That is, Fig. 12 shows the third modified example.

[0084] In Fig. 12, a relief valve 51 serving as a valve device includes a sleeve 52, a main poppet 53 serving as a valve body, and a filter 31. The relief valve 51 in Fig. 12 is a relief valve that prevents overload of a hydraulic cylinder 71. The sleeve 52 is provided with a port 54 and a valve body hole 55 that communicates with this port 54. The main poppet 53 is inserted into the valve body hole 55 of the sleeve 52. The main poppet 53 moves in the axial direction within the valve body hole 55. The filter 31 is wrapped circumferentially around the outer periphery of the sleeve 52 at a position corresponding to the port 54.

[0085] The filter 31 includes a first filter 32, a second filter 33, and a third filter 37. The first filter 32 and the second filter 33 are wound around the outer circumferential surface of the sleeve 52 with a circumferential portion of the outer circumferential surface exposed. Both circumferential ends of the first filter 32 and the second filter 33 are fixed to the outer circumferential surface of the sleeve 52. The third filter 37 is wound around the outer circumferential sides of the first filter 32 and the second filter 33. Both circumferential ends of the third filter 37 are fixed to the portions exposed from the first filter 32 and the second filter 33. In this case, both circumferential ends of the third filter 37 are fixed to the outer circumferential surface of the sleeve 52 between the circumferential ends of the first filter 32 and the second filter 33.

[0086] As shown in FIG. 12 , for example, an opening on one axial end side (the right end side in FIG. 12 ) of the sleeve 52 is connected to a bottom-side oil passage 72 serving as an actuator oil passage. The bottom-side oil passage 72 connects a bottom-side oil chamber 71A of the hydraulic cylinder 71 and a directional control valve 73. The directional control valve 73 is switched by supplying pilot pressure to hydraulic pilot chambers 73A, 73B. This causes the directional control valve 73 to supply or discharge pressure oil discharged from the hydraulic power source to or from the bottom-side oil chamber 71A or the rod-side oil chamber 71B of the hydraulic cylinder 71. Although not shown, a relief valve 51 similar to that of the bottom-side oil passage 72 is also connected to a rod-side oil passage 74 serving as an actuator oil passage that connects the rod-side oil chamber 71B of the hydraulic cylinder 71 and the directional control valve 73.

[0087] The port 54 of the sleeve 52 is connected to a tank 76 via a tank oil passage 75. When the pressure in a back pressure chamber 58, which is connected to an oil chamber 56 of a main poppet 53 via a restrictor 57 serving as an orifice, is lower than a set relief pressure, one axial end side (the right end side in FIG. 12) of the main poppet 53 abuts (seats) against a cylindrical main valve seat member 59. Also, one axial end side (the right end side in FIG. 12) of the pilot poppet 60 abuts (seats) against a cylindrical pilot valve seat member 61. In this case, the bottom-side oil passage 72 and the tank oil passage 75 are blocked.

[0088] In response to this, the pressure in the oil chamber 56 and the back pressure chamber 58 of the main poppet 53 increases, and the pilot poppet 60 is displaced toward the other axial direction (to the left in FIG. 12 ) against the pilot poppet spring 62, causing the pilot poppet 60 to separate from (unseat) the pilot valve seat member 61. Accordingly, when the main poppet 53 separates from (unseats) the main valve seat member 59 toward the other axial direction (to the left in FIG. 12 ), the pressurized oil in the bottom-side oil passage 72 is guided to the port 54 through the gap between the main poppet 53 and the main valve seat member 59. This allows the pressurized oil in the bottom-side oil passage 72 to be released (relieved) to the tank oil passage 75.

[0089] The relief valve 51 also functions as a negative pressure prevention valve for the hydraulic cylinder 71 (hydraulic actuator). For example, when the tank oil passage 75 becomes higher in pressure than the bottom-side oil passage 72 and the hydraulic force acting on the main valve seat member 59 overcomes the biasing force of the biasing spring 63, the main valve seat member 59 moves away from the main poppet 53. This allows hydraulic oil to be drawn from the tank 76 side to the hydraulic cylinder 71 side (bottom-side oil passage 72) through the tank oil passage 75 and the port 54. Because the relief valve 51 also has a negative pressure prevention function, the direction of hydraulic oil flowing through the port 54 is reversed during relief operation and negative pressure prevention operation. That is, a bidirectional flow occurs through the port 54. Therefore, in the third modified example, the filter 31 has a three-layer structure including a first filter 32, a second filter 33, and a third filter 37.

[0090] In the third modified example, similarly to the embodiment, the first modified example, and the second modified example, the plurality of filters 32, 33, and 37 can be stably attached to the sleeve 52. In particular, according to the third modified example, the relief valve 51 serving as the valve device has a poppet (main poppet 53) as the valve element. Therefore, the plurality of filters 32, 33, and 37 can be stably attached to the sleeve 52 in a valve device (poppet valve) that uses a poppet (conical poppet, spherical poppet) as the valve element.

[0091] In the embodiment and each modified example, the solenoid valve 1 and the relief valve 51 are shown as examples of valve devices to which the filter 31 is attached. However, the present invention is not limited to these, and the filter 31 in the embodiment and each modified example can be attached to various valve devices (spool valves, poppet valves) such as pressure control valves, flow control valves, relief valves, and throttle valves. Furthermore, the valve device is not limited to solenoid valves equipped with an actuator driven by a power supply, and may also be a valve device without an actuator. Furthermore, the port covered by the filter may be any port through which a liquid flows. In other words, the ports covered by the filter are not limited to pump ports, tank ports, and actuator ports.

[0092] The embodiments and modifications are merely examples, and it goes without saying that partial substitution or combination of the configurations shown in different embodiments and modifications is possible. [Explanation of symbols]

[0093] 1. Solenoid valve (valve device) 2 Solenoid section (actuator) 21 Valve section 22 sleeve 22A sliding hole (valve body hole) 22E pump port 23 Spool (valve body) 31 filters 32 First filter 33 Second filter 32A one end 32B other end 33 Second filter 33A One end 33B other end 34, 35, 36 Spot welding (welding) 37 Third Filter 51 Relief valve (valve device) 52 Sleeve 53 Main poppet (poppet, valve body) 54 ports 55 Valve body hole

Claims

1. a sleeve provided with a port and a valve body hole communicating with the port; a valve element inserted into the valve element hole of the sleeve and moving axially within the valve element hole; a filter wound circumferentially around the outer circumferential side of the sleeve at a position corresponding to the port; In a valve device comprising: The filter is a first filter wound around the outer peripheral surface of the sleeve with a circumferential portion of the outer peripheral surface exposed, and both circumferential ends of the first filter fixed to the outer peripheral surface of the sleeve; a second filter wound around the outer circumferential side of the first filter, with both circumferential ends fixed to portions of the outer circumferential surface of the sleeve that are exposed from the first filter between both circumferential ends of the first filter; A valve device comprising:

2. 2. The valve device according to claim 1, wherein the second filter is wrapped around the outer peripheral surface of the sleeve in a state where a part of the outer peripheral surface in the circumferential direction is exposed.

3. 2. The valve device according to claim 1, wherein the second filter is wrapped around the entire outer circumferential surface of the sleeve.

4. 2. The valve device according to claim 1, wherein the first filter has a larger mesh size and a higher strength than the second filter.

5. 2. The valve device according to claim 1, wherein the second filter has a larger mesh size and a higher strength than the first filter.

6. The filter is the first filter; the second filter; a third filter that is wrapped around the outer periphery of the second filter over the entire periphery of the outer periphery of the sleeve or in a state in which a circumferential portion of the outer periphery of the sleeve is exposed, and both circumferential ends of the third filter are fixed to portions of the outer periphery of the sleeve that are exposed from the first filter and the second filter; 3. The valve device according to claim 2, further comprising:

7. 7. The valve device according to claim 6, wherein the first filter and the third filter have coarser meshes and greater strength than the second filter.

8. 2. The valve device according to claim 1, wherein the first filter and the second filter are fixed to the outer peripheral surface of the sleeve by welding.

9. 2. The valve device according to claim 1, wherein the valve element is a spool or a poppet.

10. 2. The valve device according to claim 1, wherein the valve element is displaced relative to the sleeve by an actuator that is driven by a supply of electric power.

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