Spool valve

Abstract

Provided is a spool valve capable of accurately controlling a flow rate.　A spool valve 1 comprises: a sleeve 2 in which a plurality of ports P1 to P4 is formed; and a spool 3 in which a land 30 is formed, at least a portion of which can be in sliding contact with an inner wall 23 of the sleeve 2. The land 30 and the inner wall 23 form a seal part S. The seal part S has a sliding contact area A1 and a fluid introduction area A2. The land 30 is formed so that the sliding contact area A1 of the seal part S is enlarged as the spool 3 moves from a stroke start position.

Description

Spool valve

[0001] The present invention relates to spool valves, for example, spool valves used in fluid control.

[0002] Valves used to control fluids in various industrial fields can control the pressure and flow rate of fluids by adjusting the valve opening by moving the valve disc. Typical valve configurations for such valves include the spool type, in which the valve disc moves parallel to the opening that serves as the valve seat, and the lift type, in which the valve disc moves perpendicular to the opening that serves as the valve seat. Spool types, in particular, have the advantage that they can accommodate a wide range of fluid pressures because no force from the fluid acts in the direction of movement of the spool, which serves as the valve disc, and they also have the advantage of being able to easily configure a multi-port structure.

[0003] One example of such a spool-type valve is the spool valve device disclosed in Patent Document 1. A spool, which is driven axially by a solenoid device, is inserted into a sleeve. The sleeve is provided with multiple ports. The spool has multiple lands that slide against the inner wall of the sleeve. The radially overlapping portions of the lands and the inner wall form a seal.

[0004] JP 2021-42828 A (pages 6 and 7, Figure 1)

[0005] In a spool valve device such as that described in Patent Document 1, multiple annular grooves are formed in a land at the end of the spool on the solenoid device side, and fluid is introduced into these annular grooves. When the spool becomes eccentric or tilts relative to the sleeve, some of the fluid in the annular grooves is compressed, generating a force that pushes back against the land. This reduces the locking force when hydraulic lock occurs.

[0006] In addition, the portion of the land closer to the solenoid device than the annular groove primarily contributes to sealing. However, because the area of ​​the land that is in sliding contact with the inner wall and closer to the annular groove is constant regardless of the spool stroke, there is a risk of leakage if the land tilts or shifts radially relative to the inner wall during the spool stroke.

[0007] The present invention has been made in view of the above-mentioned problems, and has as its object to provide a spool valve that can control the flow rate with high precision.

[0008] In order to solve the above problem, the spool valve of the present invention is a spool valve including: a sleeve having a plurality of ports formed therein; and a spool having a land formed therein, at least a portion of which can be in sliding contact with the inner wall of the sleeve; the land and the inner wall form a seal portion; the seal portion has a sliding contact area and a fluid introduction area; and the land is formed so that the sliding contact area of ​​the seal portion expands as the spool moves from the stroke start position. In this way, since the seal portion expands as the spool moves from the stroke start position, leakage associated with spool movement can be easily reduced. This makes it possible to control the flow rate with high precision.

[0009] The land may be stepped, having a sliding portion that forms the sliding contact area and a small-diameter portion that forms the fluid introduction area. This separates the sealing function of the sliding contact area from the locking force reduction function of the fluid introduction area, allowing the spool to move stably. This results in high-precision control of the spool valve.

[0010] The land may have a sliding portion that forms the sliding contact area and a polygonal portion that forms the fluid introduction area, thereby generating a force that quickly pushes back the land.

[0011] The land may have a sliding portion that forms the sliding contact area and a grooved portion that has a groove that forms the fluid introduction area, thereby generating a force that quickly pushes back the land.

[0012] A part of the sliding portion may be located outside the sleeve from the stroke start position to the stroke end position of the spool, thereby ensuring a sliding contact area that expands from the stroke start position to the stroke end position of the spool.

[0013] The length of the fluid introduction area at the stroke start position of the spool may be at least half of the length of the seal portion, which makes it possible to both prevent leakage when the spool is stopped at the stroke start position and reduce the locking force at the start of movement.

[0014] The length of the fluid introduction area at the stroke terminal position of the spool may be at least half of the length of the seal portion, thereby achieving both leakage prevention and a reduction in locking force from the stroke start position to the stroke terminal position.

[0015] The fluid introduction region may be in communication with the in-port or out-port, which reduces fluid leakage and allows approximately the same amount of fluid to pass through the out-port as the amount of fluid that flows in from the in-port.

[0016] FIG. 4 is a cross-sectional view, partially cut away, showing the spool valve of embodiment 1 according to the present invention in a closed state. FIG. 5 is a cross-sectional view of the area surrounded by the dashed dotted line in FIG. 1. FIG. 6 is a cross-sectional view of the spool in FIG. 1 taken along line A-A. FIG. 7 is a cross-sectional view, partially cut away, showing the spool valve of embodiment 1 in an open state. FIG. 8 is a cross-sectional view for explaining modified example 1 of the land. FIG. 9 is a cross-sectional view for explaining modified example 2 of the land. FIG. 10 is a cross-sectional view, partially cut away, showing the spool valve of embodiment 2 according to the present invention in a closed state.

[0017] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A spool valve according to an embodiment of the present invention will be described below with reference to the accompanying drawings.

[0018] A solenoid valve as a spool valve according to a first embodiment will be described with reference to Figures 1 to 7. In the following description, the left and right sides of the spool valve as viewed from the front of Figure 1 will be taken as the left and right sides.

[0019] 1, the solenoid valve 1 is a normally closed spool valve in which the flow path between the inlet port P1 and the outlet port P2 is closed when the coil 12 of the solenoid device 10 is not energized and in an off state. The solenoid valve 1 is used in hydraulically controlled devices such as an automatic transmission of a vehicle. However, the solenoid valve 1 may also be applied to other devices.

[0020] The solenoid valve 1 includes a sleeve 2, a spool 3, a retainer 4, a spring 5, and a solenoid device 10 as a drive source. The sleeve 2, the spool 3, and the retainer 4 are made of a material such as aluminum, iron, stainless steel, or resin.

[0021] The sleeve 2 is formed in a stepped cylindrical shape. The spool 3 is also formed in a stepped columnar shape. The spool 3 is inserted into the sleeve 2 and is capable of reciprocating in the axial direction. The sleeve 2 and the spool 3 will be described in detail later.

[0022] The retainer 4 is fixed to the axial right end of the sleeve 2. The spring 5 is disposed in a compressed state between the spool 3 and the retainer 4.

[0023] The solenoid device 10 includes a solenoid case 11 , a coil 12 , a first fixed core 13 , a spacer 14 , a second fixed core 15 , an annular plate 16 , a movable core 17 , a rod 18 , and a stopper 19 .

[0024] The solenoid case 11 is made of a magnetic material and has a cylindrical shape. The left end of the sleeve 2 is fixed by crimping to the right end of the solenoid case 11. The sleeve 2 abuts against an annular plate 16 in the axial direction.

[0025] The coil 12 is disposed within the solenoid case 11. A first stationary core 13, a spacer 14, and a second stationary core 15 are disposed radially inward of the coil 12.

[0026] The first stator core 13 and the second stator core 15 are made of a magnetic material and are cylindrically formed. The spacer 14 is made of a non-magnetic material and is cylindrically formed. The first stator core 13 and the second stator core 15 are connected by the spacer 14.

[0027] The annular plate 16 is made of a magnetic material and has an annular plate shape, and is molded with resin together with the coil 12 .

[0028] The movable core 17 is made of a magnetic material and has a cylindrical shape. The movable core 17 is accommodated inside the first fixed core 13, the spacer 14, and the second fixed core 15 so as to be able to reciprocate in the axial direction.

[0029] The rod 18 is made of a non-magnetic material and has a cylindrical shape. The rod 18 is inserted into a through-hole in the second fixed core 15 so as to be able to move back and forth in the axial direction. The rod 18 receives the biasing force of the spring 5 via the spool 3 and is pressed against the movable core 17 in the axial direction.

[0030] The stopper 19 is made of a non-magnetic material and has an annular shape. The stopper 19 is fixed to the second stationary core 15.

[0031] In the solenoid device 10, magnetic flux generated by supplying power to the coil 12 from a power source (not shown) flows through a magnetic path mainly composed of the solenoid case 11, the annular plate 16, the second fixed core 15, the movable core 17, and the first fixed core 13. This generates an attractive force that attracts the movable core 17 to the second fixed core 15 side.

[0032] Next, a description will be given of the sleeve 2 and the spool 3. The sleeve 2 is formed in a stepped cylindrical shape with a through-hole 20 formed in the radial center thereof and penetrating in the axial direction.

[0033] The through hole 20 extends in the axial direction with approximately the same diameter. Two large diameter hole sections 21, 22 whose diameters are enlarged toward the outer diameter side are formed in the axial center of the through hole 20. The large diameter hole section 21 is spaced apart from the large diameter hole section 22 on the left side in the axial direction.

[0034] Additionally, multiple ports P1 to P4 through which a fluid can flow are formed in the sleeve 2. The ports P1 to P4 are arranged in the following order from left to right: inlet port P1 as an in-port, outlet port P2 as an out-port, discharge port P3, and feedback port P4. Note that the ports P1 to P3 are shown in dashed lines because they are formed at different circumferential positions from the feedback port P4.

[0035] The inlet port P1 communicates with the left end of the through hole 20 in the axial direction and the large diameter hole portion 21. The outlet port P2 communicates with the large diameter hole portion 21 on the left side. The discharge port P3 communicates with the large diameter hole portion 22 on the right side. The feedback port P4 communicates with the right end of the through hole 20 in the axial direction and the large diameter hole portion 22.

[0036] The portion of the sleeve 2 that defines the through hole 20 is referred to as an inner wall 23. The inner wall 23 is formed so that three lands 30 to 32 of the spool 3 can slide against it.

[0037] The spool 3 is formed in a stepped cylindrical shape having three lands 30 to 32 and four shaft portions 33a to 33d. The axes of the three lands 30 to 32 and the four shaft portions 33a to 33d are substantially aligned.

[0038] The lands 30 to 32 and shaft portions 33a to 33d are arranged in the following order from left to right: first shaft portion 33a, first land 30 as the land of the present invention, second shaft portion 33b, second land 31, third shaft portion 33c, third land 32, and fourth shaft portion 33d.

[0039] The shaft portions 33a to 33d each have a smaller diameter than the lands 30 to 32 and extend in the axial direction with approximately the same diameter.

[0040] The first shaft portion 33 a protrudes axially leftward from the left end of the first land 30 , and is pressed against the rod 18 of the solenoid device 10 by the biasing force of the spring 5 .

[0041] The second shaft portion 33b connects the right end of the first land 30 to the left end of the second land 31. The third shaft portion 33c connects the right end of the second land 31 to the left end of the third land 32.

[0042] The fourth shaft portion 33d protrudes axially to the right beyond the third land 32, and the spring 5 is fitted onto the outside thereof.

[0043] 2 and 3, the first land 30 has a stepped shape having a large diameter portion 34 as a sliding portion and a small diameter portion 35. In order to clearly show the stepped shape of the first land 30, the size of the small diameter portion 35 is exaggerated and shown smaller than the large diameter portion 34 in FIGS.

[0044] The large diameter portion 34 is cylindrical and extends in the axial direction with a substantially constant diameter. The large diameter portion 34 has an outer diameter that is slightly smaller than the inner diameter of the inner wall 23 of the sleeve 2.

[0045] The large diameter portion 34 is capable of reciprocating axially while in sliding contact with the inner wall 23. The region where the large diameter portion 34 and the inner wall 23 overlap in the radial direction and are capable of sliding contact is the sliding contact region A1 of the present invention. The sliding contact region A1 functions as a seal portion S that inhibits the flow of fluid together with the fluid introduction region A2.

[0046] The outer diameter of the large diameter portion 34 is approximately the same as the outer diameter of each of the second land 31 and the third land 32. The portions of the second land 31 and the third land 32 that overlap with the inner wall 23 in the radial direction and are capable of sliding contact with the inner wall 23 function as sealing portions.

[0047] The outer diameters of the lands 30 to 32 do not have to be approximately the same, but it is preferable that any two lands have approximately the same diameter but are larger than the other one. The inner diameter of the inner wall may be changed as appropriate depending on the outer diameter of the land.

[0048] The small diameter portion 35 is cylindrical and has a smaller diameter than the large diameter portion 34 , and extends axially rightward from the right end of the large diameter portion 34 with substantially the same diameter.

[0049] The axis of the small diameter portion 35 is substantially aligned with the axis of the large diameter portion 34. The stepped shape of the first land 30 is formed by an outer circumferential surface of the large diameter portion 34, a right side surface that extends radially inward and is substantially perpendicular to the right end of the outer circumferential surface, and an outer circumferential surface of the small diameter portion 35 that extends axially rightward and is substantially perpendicular to the right side surface. The stepped shape of the first land 30 extends in the circumferential direction (see FIG. 3).

[0050] The corner formed by the right side surface of the large diameter portion 34 and the outer peripheral surface of the small diameter portion 35 may be smoothly connected, or the right side surface itself may be curved.

[0051] A small gap that allows fluid to be introduced is formed in the circumferential direction between the small diameter portion 35 and the inner wall 23. The region where the gap is formed in the radial direction between the small diameter portion 35 and the inner wall 23 is the fluid introduction region A2 of the present invention.

[0052] The fluid introduction area A2 is open to the right in the axial direction and communicates with the inlet port P1. Although the fluid introduction area A2 can introduce fluid, its radial length is extremely small, and it functions as a seal portion S that can suppress the flow of fluid together with the sliding contact area A1.

[0053] That is, the seal portion S has a sliding contact area A1 and a fluid introduction area A2. The sliding contact area A1 has a radial length that is even smaller than that of the fluid introduction area A2, and therefore has a higher sealing performance than the fluid introduction area A2.

[0054] Next, the operation of the spool 3 will be described. First, the operation when de-energized will be described. When de-energized, as shown in FIG. 1, the first land 30 of the spool 3 is pressed against the second fixed core 15 by the biasing force of the spring 5. In other words, the spool 3 is stationary in the state where it has moved to the leftmost position. This position of the spool 3 when de-energized is the stroke start position in the present invention.

[0055] At the stroke start position, the inlet port P1 and the outlet port P2 are not in communication with each other due to the seal formed by the second land 31 and the inner wall 23. In addition, because the third land 32 is located axially to the right of the inner wall 23 between the large-diameter hole portions 21 and 22, the outlet port P2 and the discharge port P3 are in communication with each other.

[0056] When current is applied, the movable core 17 moves axially to the right when the attractive force acting on the movable core 17 exceeds the biasing force of the spring 5. Following this movable core 17, the rod 18 and the spool 3 also move axially to the right.

[0057] 1, when the spool 3 moves axially to the right, the inlet port P1 and the outlet port P2 communicate with each other (see FIG. 4), and the outlet port P2 and the discharge port P3 do not communicate with each other.

[0058] Furthermore, when the annular groove formed in the third land 32 communicates with the feedback port P4 (see FIG. 4), the fluid pressure in the annular groove becomes substantially the same as the fluid pressure in the external flow path (not shown) connected to the outlet port P2 outside the solenoid valve 1. This is because the external flow path connected to the outlet port P2 is connected to a bypass flow path (not shown) connected to the feedback port P4.

[0059] As shown in Figure 4, when the movable core 17 moves further to the right and abuts against the stopper 19, the movement of the movable core 17 is restricted. At this time, the spool 3 is stationary in the state where it has moved to the farthest right. This position of the spool 3 is the stroke terminal position in the present invention.

[0060] Next, the change in the seal portion S accompanying the movement of the spool 3 will be described.

[0061] 2, the first land 30 is located at the leftmost position at the stroke start position. The first land 30 also protrudes from the left end of the large diameter portion 34 to the axial center thereof to the left, i.e., outward, of the sleeve 2. This protruding portion is located within the solenoid device 10, and more specifically, is located inside the annular plate 16.

[0062] The dimension of the large diameter portion 34 protruding outward from the sleeve 2 at the stroke start position is the maximum within the stroke range of the spool 3. Also, the axial length L11 of the sliding contact area A1 at the stroke start position is the shortest. In other words, the sliding contact area A1 is at its smallest.

[0063] At the stroke start position, the entire small diameter portion 35 overlaps the inner wall 23 in the radial direction, so the axial length L12 of the fluid introduction region A2 is at its longest.

[0064] The axial length L1 of the seal portion S at the stroke start position is the sum of the axial length L11 of the sliding contact area A1 and the axial length L12 of the fluid introduction area A2 (L1 = L11 + L12), which is the shortest. In other words, the area of ​​the seal portion S, or in other words, the area of ​​the seal portion S, is the smallest.

[0065] At the stroke start position, the axial length L12 of the fluid introduction area A2 is approximately three-quarters of the axial length L1 of the seal portion S.

[0066] When the spool 3 moves to the right in the axial direction, the first land 30 also moves to the right in the axial direction. That is, the portion of the large diameter portion 34 that protrudes axially leftward beyond the sleeve 2 is inserted into the through hole 20. That is, the sliding contact area A1 expands.

[0067] 5, at the stroke terminal position, the first land 30 is located at the rightmost position. Also, the dimension of the first land 30 that protrudes outward from the sleeve 2 is the smallest. In other words, the large diameter portion 34 of the first land 30 protrudes outward from the sleeve 2 even at the stroke terminal position.

[0068] The axial length L21 of the sliding contact area A1 at the stroke end position is the longest. In other words, the sliding contact area A1 is at its maximum.

[0069] 2, the axial length from the small diameter portion 35 at the stroke start position to the communicating passage 24 having the inlet port P1 is defined as La. Also, with reference to FIG. 5, the distance traveled by the first land 30 from the stroke start position to the stroke end position, i.e., the axial length of the stroke range of the spool 3, is defined as Ls.

[0070] The axial length La is set to be longer than the axial length Ls (La>Ls), so that the entire small diameter portion 35 overlaps the inner wall 23 in the radial direction over the stroke range of the spool 3. In other words, the axial length L12 of the fluid introduction region A2 is constant over the stroke range of the spool 3.

[0071] The axial lengths La and Ls may be changed as appropriate, but from the viewpoint of keeping the axial length L12 of the fluid introduction area A2 constant within the stroke range of the spool 3 and preventing a large amount of fluid from flowing in or out between the fluid introduction area A2 and the inlet port P1, it is preferable that the axial length La be greater than or equal to the axial length Ls (La≧Ls).

[0072] As a result, the area of ​​the seal portion S is expanded by the amount that the axial length of the sliding contact area A1 is expanded as the spool 3 moves axially to the right from the stroke start position.

[0073] 5, the axial length L2 of the seal portion S at the stroke end position is the sum of the axial length L21 of the sliding contact area A1 and the axial length L12 of the fluid introduction area A2 (L2 = L21 + L12), which is the longest. In other words, the area of ​​the seal portion S is the largest.

[0074] At the stroke end position, the axial length L12 of the fluid introduction area A2 is approximately half the axial length L2 of the seal portion S.

[0075] As described above, the solenoid valve 1 of this embodiment is formed with the fluid introduction area A2 into which fluid can be introduced. As a result, when the spool 3 becomes eccentric or tilts relative to the sleeve 2, a portion of the fluid in the fluid introduction area A2 is compressed, generating a force that pushes back the first land 30. This makes it possible to reduce the locking force when hydraulic lock occurs.

[0076] Furthermore, in the solenoid valve 1, the seal portion S expands as the sliding contact area A1 expands due to movement from the stroke start position, making it easier to reduce leakage caused by movement of the spool 3. This allows for accurate flow control.

[0077] Furthermore, the sliding contact area A1 of the solenoid valve 1 is minimized at the stroke start position, which facilitates reducing the sliding friction force that occurs at the start of movement in the sliding contact area A1 when the spool 3 is stopped at the stroke start position.

[0078] The first land 30 has a stepped shape with a large diameter portion 34 that forms the sliding contact area A1 and a small diameter portion 35 that forms the fluid introduction area A2. This separates the sealing function of the sliding contact area A1 from the locking force reduction function of the fluid introduction area A2, allowing for stable movement of the spool 3. This results in high accuracy of flow rate control in the solenoid valve 1.

[0079] Furthermore, since the first land 30 has a stepped shape, it is less likely to become entangled with contaminants, compared to a configuration in which a tapered small diameter portion that expands in diameter toward the large diameter portion 34 is connected to the large diameter portion 34, instead of a small diameter portion whose outer peripheral surface extends parallel to the axial direction.

[0080] The small diameter portion may be tapered, and such a configuration can improve the centering effect of the spool when the spool moves from the stroke start position to the stroke end position.

[0081] Furthermore, a portion of the large diameter portion 34 is located outside the sleeve 2 from the stroke start position to the stroke end position of the spool 3. This ensures that the sliding contact area A1 that expands from the stroke start position to the stroke end position of the spool 3 is secured.

[0082] Furthermore, at the stroke start position of the spool 3, the length of the fluid introduction area A2 is approximately three-quarters of the length of the seal portion S. This makes it possible to both prevent leakage when the spool 3 is stopped at the stroke start position and reduce the locking force when the spool 3 starts to move.

[0083] The length of the fluid introduction area A2 relative to the seal portion S at the stroke start position may be changed as appropriate, but it is preferable that it be at least half, and more preferably at least three-quarters, of the length, in order to be able to prevent leakage when the spool 3 is stopped at the stroke start position and to reduce the locking force when movement begins.

[0084] Furthermore, the length of the fluid introduction area A2 at the stroke terminal position of the spool 3 is approximately half the length of the seal portion S. This makes it possible to prevent leakage and reduce the locking force from the stroke start position to the stroke terminal position.

[0085] The length of the fluid introduction area A2 relative to the seal portion S at the stroke end position may be changed as appropriate, but it is preferable that it be more than half and less than three-quarters, in order to achieve both leakage prevention and reduction of locking force from the stroke start position to the stroke end position.

[0086] The fluid introduction area A2 is also connected to the inlet port P1, which reduces fluid leakage and allows approximately the same amount of fluid as that flowing in from the inlet port P1 to pass through to the outlet port P2.

[0087] Furthermore, since a portion of the large diameter portion 34 of the first land 30 is disposed inside the solenoid device 10, the sliding contact area A1 can be varied without affecting the control of the fluid.

[0088] A portion of the large diameter portion 34 is disposed inside the annular plate 16. The second stationary core 15 and the sleeve 2 abut axially on the left and right sides of the annular plate 16, respectively. The annular plate 16, the second stationary core 15, and the left end of the sleeve 2 are surrounded by the solenoid case 11. In other words, a portion of the large diameter portion 34 is isolated from the space outside the solenoid valve 1. This makes the first land 30 less susceptible to the external atmosphere in the solenoid valve 1, thereby stabilizing the movement of the spool 3.

[0089] Furthermore, since a portion of the large diameter portion 34 of the solenoid valve 1 is disposed inside the solenoid device 10, the structure can be made compact.

[0090] While the first land 30 has been described as having the large diameter portion 34 and the small diameter portion 35 that is circular in cross section, the present invention is not limited to this. As in the first land 130 of Modification 1 shown in Fig. 6 , a polygonal portion 135 that is polygonal in cross section may be connected to the large diameter portion 34. Each corner 136 of the polygonal portion 135 is disposed on approximately the same plane as the outer circumferential surface of the large diameter portion 34. Even with this configuration, a fluid introduction region into which a fluid can be introduced can be formed radially between the polygonal portion 135 and the inner wall 23.

[0091] Furthermore, the fluid introduction region formed radially between the polygonal portion 135 and the inner wall 23 is partitioned in the circumferential direction by each corner 136. As a result, when the spool 3 is eccentric or tilted relative to the sleeve 2, the fluid introduced between the two corners 136 located at the target location is easily compressed. This makes it possible to quickly generate a force that pushes back the first land 130.

[0092] Moreover, each corner 136 of the polygonal portion 135 is slidable against the inner wall 23. Therefore, the sliding friction force generated by the first land 130 sliding against the inner wall 23 is slightly larger than that of the first land 30 of the first embodiment, and is about the same as that of the first land 230 of the second modification example described below.

[0093] 7 , a grooved portion 235 having a plurality of grooves 236 extending in the axial direction may be connected to the large diameter portion 34. The grooved portion 235 has an outer peripheral surface extending in the circumferential direction between two grooves 236 and disposed on approximately the same plane as the outer peripheral surface of the large diameter portion 34. Even with this configuration, a fluid introduction region into which a fluid can be introduced can be formed between the grooved portion 235 and the inner wall 23 in the radial direction.

[0094] Furthermore, since the groove 236 has ends in the circumferential direction, when the spool 3 is eccentric or tilted relative to the sleeve 2, the fluid introduced into the groove 236 located at the target location is easily compressed. This allows a force to quickly push back the first land 230 to be generated.

[0095] Furthermore, the grooved portion 235 has an outer peripheral surface extending in the circumferential direction remaining between the two grooves 236. Therefore, the first land 230 can improve the sealing performance compared to the first land 30 of the first embodiment and the first land 130 of the first modification.

[0096] Next, a spool valve according to a second embodiment will be described with reference to Fig. 8. Note that the configuration is the same as that of the first embodiment, and therefore a description of the configuration that overlaps with the first embodiment will be omitted.

[0097] As shown in FIG. 8, the solenoid valve 301 includes a sleeve 2 , a spool 303 , a retainer 4 , a spring 5 , and a solenoid device 310 .

[0098] The spool 303 is formed with a flange 338 that projects radially outward from the left end of the large diameter portion 334 of the first land 330 .

[0099] The flange 338 is disposed on the inner diameter side of the annular plate 316 of the solenoid device 310 so as to be able to move back and forth in the axial direction. In this embodiment, the axial dimension of the annular plate 316 is made longer by the thickness of the flange 338, i.e., the axial dimension, so that the stroke range of the spool 303 is substantially the same as in the first embodiment.

[0100] As a result, the solenoid valve 301 can restrict the spool 303 from moving leftward from the stroke start position by the flange 338 moving axially leftward coming into contact with the second fixed iron core 15.

[0101] Furthermore, the solenoid valve 301 can restrict the spool 303 from moving to the right from the stroke end position by the flange 338 moving axially rightward and coming into contact with the sleeve 2 .

[0102] Therefore, the solenoid valve 301 can omit the stopper 19 described in the first embodiment.

[0103] Although the embodiments of the present invention have been described above with reference to the drawings, the specific configuration is not limited to these embodiments, and the present invention also includes modifications and additions that do not deviate from the gist of the present invention.

[0104] For example, in the first and second embodiments, the spool valve is described as being driven by a solenoid, but the invention is not limited to this and may be driven by other methods such as manual or hydraulic.

[0105] Furthermore, in the first and second embodiments, the spool valve has been described as being of a normally closed type, but this is not limitative and the spool valve may be of a normally open type.

[0106] In addition, in the first and second embodiments, the land of the present invention is described as the first land, but this is not limited thereto and other lands may be used. However, it is preferable that the land be provided at the end of the spool, as this will have less of an effect on fluid control. For example, if the land is provided at the third land in the first and second embodiments, by disposing a portion of the large diameter portion inside the retainer, it will have less of an effect on fluid control.

[0107] In addition, in the first and second embodiments, the land of the present invention is described as being only the first land, but this is not limitative, and there may be a plurality of lands of the present invention.

[0108] Furthermore, in the first and second embodiments, the large diameter portion and the small diameter portion are described as being connected to each other, but this is not limited to this. A medium diameter portion having a diameter smaller than that of the large diameter portion and a diameter larger than that of the small diameter portion may be provided between the large diameter portion and the small diameter portion, or a polygonal portion as in the first modified example or a grooved portion as in the second modified example may be provided, and modifications may be made as appropriate.

[0109] In addition, in the first and second embodiments, the large diameter portion and the small diameter portion capable of forming a seal are described as being connected to each other, but this is not limiting and they do not have to be connected. For example, the large diameter portion and the small diameter portion may be separated by an annular groove that cannot function as a seal.

[0110] In addition, in the first and second embodiments, the inlet port is the inlet port and the outlet port is the outlet port, but this is not limiting, and for example, if the fluid flows from the feedback port to the outlet port, the inlet port may be the feedback port and the outlet port may be the outport. In other words, if the port on the upstream side in the fluid flow direction is the inlet port and the port on the downstream side is the outport, the types of ports may be changed as appropriate.

[0111] Furthermore, in Examples 1 and 2, it was explained that the fluid introduction area is constant throughout the stroke range, but this is not limited to this, and the axial length of the fluid introduction area may change, for example, by overlapping radially with the large diameter hole portion.

[0112] REFERENCE SIGNS LIST 1 Solenoid valve 2 Sleeve 3 Spool 10 Solenoid device 20 Through hole 23 Inner wall 30 First land (land) 34 Large diameter portion (sliding portion) 35 Small diameter portion 80 Rod 130 First land 135 Polygonal portion 136 Corner 230 First land 235 Grooved portion 236 Groove 301 Solenoid valve 303 Spool 310 Solenoid device 330 First land 334 Large diameter portion 338 Flange A1 Sliding contact area A2 Fluid introduction area P1 Inlet port P2 Outlet port P3 Discharge port P4 Feedback port S Sealing portion

Claims

1. A spool valve comprising a sleeve having a plurality of ports formed therein, and a spool having a land formed thereon, at least a portion of which can slide against the inner wall of the sleeve, wherein the land and the inner wall form a seal portion, the seal portion having a sliding area and a fluid introduction area, and the land is formed so that the sliding area of ​​the seal portion expands as the spool moves from the stroke start position.

2. A spool valve as set forth in claim 1, wherein said land is stepped and has a sliding portion that forms said sliding contact area and a small diameter portion that forms said fluid introduction area.

3. A spool valve according to claim 1, wherein said land has a sliding portion that forms said sliding contact area and a polygonal portion that forms said fluid introduction area.

4. A spool valve as set forth in claim 1, wherein said land has a sliding portion that forms said sliding contact area, and a grooved portion that has a groove formed therein that forms said fluid introduction area.

5. A spool valve as set forth in any one of claims 2 to 4, wherein a part of said sliding portion is located outside said sleeve from the stroke start position to the stroke end position of said spool.

6. A spool valve as set forth in claim 1, wherein the length of said fluid introduction area at the stroke start position of said spool is at least half the length of said seal portion.

7. A spool valve according to claim 6, wherein the length of said fluid introduction area at the stroke end position of said spool is at least half the length of said seal portion.

8. The spool valve of claim 1, wherein the fluid introduction region communicates with an in-port or out-port.

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