Spool valve

Abstract

To provide a spool valve capable of efficiently obtaining an alignment effect and an effect of suppressing a leak amount.SOLUTION: A spool valve 1 includes a valve hole forming body 2 formed with a valve hole 20 in an axial direction D, and a spool 3 capable of moving within a predetermined axial range within the valve hole 20. The spool 3 has at least one closing land having a portion that continues closing a fourth inter-port hole portion 25d of the valve hole 20, which is located between an input port 21 and a feedback port 24 in the valve hole 20, during movement from one end to the other end of the axial range. The at least one closing land is a variable closing land 300. On the outer peripheral portion of the variable closed land 300, groove portions 30 are formed at a plurality of locations in the axial direction D along the circumferential direction of the spool 3. Between when the spool 3 is positioned at one end of the axial range and when the spool 3 is positioned at the other end of the axial range, the number of the grooves 30 of the variable closing land 300, which fit within the fourth inter-port hole portion 25d, changes.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a spool valve. [Background technology]

[0002] Patent Document 1 discloses a solenoid valve comprising a solenoid unit, a valve sleeve, and a spool. The solenoid unit has a plunger that moves axially in response to the energization of a coil. The valve sleeve is formed with a valve orifice into which a spool that moves in conjunction with the movement of the plunger is inserted, a supply port that supplies hydraulic oil to the valve orifice, an output port that outputs hydraulic oil from the valve orifice, and a feedback port that returns a portion of the hydraulic oil output from the output port to the valve orifice. The spool has multiple lands for adjusting the flow rate of hydraulic oil between each port in the valve orifice.

[0003] Among the spool's multiple lands, the land provided in the inter-port hole portion, which is the portion of the valve hole between the input port and the feedback port, is a blocking land that continuously blocks the space between the input port and the feedback port in the valve hole while the spool moves. A groove is formed around the entire periphery of the blocking land. By forming a groove in the blocking land, the groove is filled with hydraulic oil, which acts to center the spool in the valve hole. This prevents the spool from becoming radially eccentric with respect to the valve hole, causing fluid sticking. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-197848 Summary of the Invention [Problem to be solved by the invention]

[0005] The greater the number of grooves that fit within the inter-port bore portion, the greater the alignment effect, but the greater the amount of hydraulic oil that leaks between the ports. Therefore, the solenoid valve described in Patent Document 1 has room for improvement in terms of efficiently obtaining the alignment effect and the effect of suppressing the amount of leakage.

[0006] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a spool valve that can efficiently obtain the effects of aligning and suppressing the amount of leakage. [Means for solving the problem]

[0007] In order to achieve the above object, the present invention provides a valve hole formation body having a valve hole formed in the axial direction and a plurality of ports formed at a plurality of axial locations for opening the valve hole to the outer periphery, and a spool movable within a predetermined axial range within the valve hole, wherein the spool has at least one blockage land having a portion that continues to block an inter-port hole portion of the valve hole located between two adjacent ports while the spool moves from one end to the other end of the axial range, and at least one of the blockage lands is a variable blockage land, and grooves are formed on the outer periphery of the variable blockage land at a plurality of axial locations along the circumferential direction of the spool, and the number of grooves of the variable blockage land that fit within the inter-port hole portion changes between when the spool is located at one end of the axial range and when the spool is located at the other end of the axial range. and when the spool is positioned at one end of the axial range and when the spool is positioned at the other end of the axial range, the plurality of grooves of the variable blocking land are contained within the inter-port hole. Provide a spool valve 。 Furthermore, in order to achieve the above-mentioned object, the present invention provides a valve hole formation body having a valve hole formed in the axial direction and a plurality of ports formed at a plurality of axial locations for opening the valve hole to the outer periphery, and a spool movable within a predetermined axial range within the valve hole, wherein the spool has at least one blockage land having a portion that continues to block an inter-port hole portion of the valve hole located between two adjacent ports while the spool moves from one end to the other end of the axial range, and at least one of the blockage lands is a variable blockage land, and grooves are formed on the outer periphery of the variable blockage land at a plurality of axial locations along the circumferential direction of the spool, so that the number of grooves of the variable blockage land that fit within the inter-port hole portion changes between when the spool is positioned at one end of the axial range and when the spool is positioned at the other end of the axial range, and the valve hole formation body is the port through which hydraulic oil is input to the valve hole. a spool valve having an input port, an output port that is the port for outputting hydraulic oil from the valve orifice, and a feedback port that is the port for returning a portion of the hydraulic oil output from the output port to the valve orifice, wherein the variably blocking land opens and closes the inter-port hole located between the input port and the output port in accordance with axial movement of the spool, and continues to block the inter-port hole located between the input port and the feedback port while the spool moves from one end to the other end of its axial range, and the number of grooves contained in the inter-port hole located between the input port and the feedback port is greater when the variably blocking land blocks the inter-port hole located between the input port and the output port than when the variably blocking land opens the inter-port hole located between the input port and the output port. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a spool valve that can efficiently obtain the effects of alignment and suppression of leakage amount. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 2 is a cross-sectional view of a spool valve according to the first embodiment. [Figure 2]FIG. 2 is a plan view of the spool valve according to the first embodiment. [Figure 3] 2 is a cross-sectional view showing a state in which a spool valve is attached to a transmission case in the first embodiment. FIG. [Figure 4] 2 is an enlarged view of a part of FIG. 1, showing a state in which the spool is at the reverse end position. [Figure 5] 2 is an enlarged view of a portion of FIG. 1, showing a state in which the spool is at the forward end position. [Figure 6] 10 is an explanatory diagram showing a force acting on a third land when no groove is formed in the third land. FIG. [Figure 7] 5 is an explanatory diagram showing a force acting on a third land in which a plurality of grooves are formed in the first embodiment. FIG. [Figure 8] FIG. 6 is a cross-sectional view of a spool valve according to a second embodiment. [Figure 9] 9 is an enlarged view of a portion of FIG. 8, showing the spool in the reverse end position. [Figure 10] 9 is an enlarged view of a portion of FIG. 8, showing the spool in a forward end position. DETAILED DESCRIPTION OF THE INVENTION

[0010] [First embodiment] A first embodiment of the present invention will be described with reference to Figures 1 to 7. The embodiment described below is shown as a preferred specific example for carrying out the present invention, and although various technically preferable technical matters are specifically exemplified, the technical scope of the present invention is not limited to this specific embodiment.

[0011] (Spool valve 1) Fig. 1 is a cross-sectional view of a spool valve 1 in this embodiment. Fig. 2 is a plan view of the spool valve 1 in this embodiment. Fig. 3 is a cross-sectional view showing the spool valve 1 attached to a transmission case 12.

[0012] The spool valve 1 of this embodiment is a solenoid valve that axially moves a spool 3 disposed in a valve hole 20 of a valve hole formation body 2 by energizing and deenergizing an electromagnetic solenoid 4. The spool valve 1 is used, for example, for hydraulic control of a hydraulic actuator in an automobile transmission.

[0013] As shown in FIG. 1, the spool valve 1 comprises a valve hole formation body 2, a spool 3, an electromagnetic solenoid 4, and a biasing member 5. The valve hole formation body 2 has an axial valve hole 20 formed therein. The spool 3 is configured to be movable within a predetermined axial range within the valve hole 20 of the valve hole formation body 2. The electromagnetic solenoid 4 is an actuator that, when energized, applies a moving force to the spool 3 to move the spool 3 to one side in the axial direction D. The biasing member 5 is a coil spring that biases the spool 3 to the other side in the axial direction D. Note that the term "axial direction D" simply refers to the axial direction of the spool 3. In addition, the side of the axial direction D where the electromagnetic solenoid 4 is located relative to the valve hole 20 is referred to as the rearward side Dr, and the opposite side is referred to as the forward side Df.

[0014] As shown in Fig. 3, in this embodiment, the valve hole formation body 2 is configured by a valve body and is attached to the transmission case 12, which is the attachment target. The valve hole formation body 2 is made of metal formed by casting using a mold. As shown in Fig. 2, six valve holes 20 are formed in parallel in the valve hole formation body 2. Each valve hole 20 is formed to pass through the valve hole formation body 2 in the axial direction D. A spool 3 is housed in each of the six valve holes 20.

[0015] As shown in FIGS. 1 to 3, the valve hole formation body 2 is formed with an input port 21, an output port 22, first to third discharge ports 23a to 23c, and a feedback port 24 corresponding to each valve hole 20. The input port 21 is a port for supplying hydraulic oil into the valve hole 20. The output port 22 is a port for outputting hydraulic oil from the valve hole 20 to a controlled object (e.g., a hydraulic actuator of a transmission). The first to third discharge ports 23a to 23c are ports for discharging hydraulic oil to a drain tank (not shown). The feedback port 24 is a port for returning a portion of the hydraulic oil output from the output port 22, thereby applying hydraulic pressure toward the rear Dr to the spool 3. Each port is a hole that opens the valve hole 20 to the outer circumferential side.

[0016] A first exhaust port 23a, a second exhaust port 23b, an output port 22, an input port 21, a feedback port 24, and a third exhaust port 23c are provided in order from the rear Dr corresponding to each valve hole 20. When there is no need to particularly distinguish between the input port 21, the output port 22, the first to third exhaust ports 23a to 23c, and the feedback port 24, they will simply be referred to as "ports."

[0017] Each port opens to a mounting surface 2a, which is the surface of the valve hole formation body 2 that is superimposed on the transmission case 12. The mounting surface 2a is a surface parallel to the axial direction D. Note that in FIG. 2, the opening shape of each port is hatched for convenience. As shown in FIG. 3, each port is connected to one of an input oil passage 12a, an output oil passage 12b, a feedback oil passage 12c, and a discharge oil passage 12d formed in the transmission. The input oil passage 12a is connected to an input port 21 and supplies hydraulic oil to the input port 21. The output oil passage 12b is connected to an output port 22 and guides the hydraulic oil output from the output port 22 to a hydraulic supply target such as a hydraulic actuator. The feedback oil passage 12c branches from the output oil passage 12b and is connected to a feedback port 24, and guides a portion of the hydraulic oil to the feedback port 24. The discharge oil passage 12d is connected to a discharge port and guides the hydraulic oil discharged from the discharge port to a drain tank.

[0018] 1 and 3, the valve hole 20 has, in order from the rear end Dr in the axial direction D, a first inter-port hole portion 25a, a second inter-port hole portion 25b, a third inter-port hole portion 25c, a fourth inter-port hole portion 25d, and a fifth inter-port hole portion 25e. Each of the first to fifth inter-port hole portions 25a to 25e is a portion between adjacent ports in the valve hole 20. The first inter-port hole portion 25a is located between the first exhaust port 23a and the second exhaust port 23b. The second inter-port hole portion 25b is located between the second exhaust port 23b and the output port 22. The third inter-port hole portion 25c is located between the output port 22 and the input port 21. The fourth inter-port hole portion 25d is located between the input port 21 and the feedback port 24. The fifth inter-port hole 25e is located between the feedback port 24 and the third exhaust port 23c.

[0019] Each of the first to fifth inter-port holes 25a to 25e is a portion of the valve hole 20 where the spacing between the land and the land is narrowed to suppress the flow of hydraulic oil between the first to fifth inter-port holes 25a to 25e and lands (first to fourth lands 31 to 34) of the spool 3, which will be described later. A small gap is formed between the outer diameter of the land and the inner diameter of the inner circumferential surface of each of the first to fifth inter-port holes 25a to 25e, allowing a small amount of hydraulic oil to flow through the gap. Each of the first to fifth inter-port holes 25a to 25e is formed in a straight cylindrical shape in the axial direction D.

[0020] The valve hole formation body 2 has first and second bolt holes 261, 262 formed therethrough in a direction perpendicular to the mounting surface 2a for fastening the valve hole formation body 2 to the transmission case 12. As shown in FIG. 3, the first and second bolt holes 261, 262 are bolt insertion holes for inserting bolts B1. As shown in FIG. 2, the first bolt hole 261 is formed so as to open to the outer periphery of the mounting surface 2a of the valve hole formation body 2. The second bolt hole 262 is formed so as to open to a region of the mounting surface 2a that is more inward than the first bolt hole 261. A plurality of first and second bolt holes 261, 262 are formed.

[0021] 3, the valve hole formation body 2 is fastened to the transmission case 12 by inserting a bolt B1 into the first or second bolt hole 261, 262 and screwing it into a female threaded hole (not shown) provided in the transmission case 12. In this embodiment, the first and second bolt holes 261, 262 are bolt insertion holes for inserting the bolt B1, but they may also be female threaded holes for screwing in the bolt B1. In this case, a bolt insertion hole is formed in the transmission case 12, and the bolt B1 is inserted into the bolt insertion hole from the transmission case 12 side and screwed into the first or second bolt hole 261, 262, thereby fixing the transmission case 12 and the valve hole formation body 2 to each other.

[0022] Of the ports formed corresponding to each valve hole 20, the shortest distance between at least one of the first and second bolt holes 261, 262 and the input port 21 is shorter than the shortest distance between the second bolt hole 262 and the feedback port 24. As an example, as shown in FIG. 2 , of the input port 21, the output port 22, the first to third exhaust ports 23a to 23c, and the feedback port 24 that communicate with the valve hole 20 adjacent to the second bolt hole 262, the shortest distance between the second bolt hole 262 and the input port 21 is shorter than the shortest distance between the second bolt hole 262 and the feedback port 24. Furthermore, of the multiple first bolt holes 261, the first bolt hole 261 formed at the end of the rear Dr is shorter than the shortest distance between the input port 21 and the feedback port 24, of the input port 21, the output port 22, the first to third exhaust ports 23a to 23c, and the feedback port 24 that communicate with each valve hole 20.

[0023] 1 and 3, the rear end Dr of the valve hole 20 is closed by a plug 11. The plug 11 has a screw thread on its outer periphery and is screwed into a female threaded hole provided on the inner periphery of the valve hole 20. An electromagnetic solenoid 4 is disposed in the front end Df of the valve hole 20.

[0024] The electromagnetic solenoid 4 includes a solenoid case 41, a bobbin 42, an electromagnetic coil 43, a solenoid core 44, a bracket 45, a plunger 46, and a shaft 47. The solenoid case 41 is made of a soft magnetic material such as iron and houses each of the components of the electromagnetic solenoid 4. The solenoid case 41 has a cylindrical shape with a bottom that opens toward the front Df. The bobbin 42 is made of an electrically insulating material and is held by the solenoid case 41. The electromagnetic coil 43 is wound around the bobbin 42.

[0025] The solenoid core 44 is made of a soft magnetic material and is fixed inside the case. The bracket 45 is fastened to the valve hole formation body 2 using bolts B2. The bracket 45 abuts against the front surface of the solenoid core 44. The bracket 45 has a protruding portion 451 that protrudes outward beyond the solenoid case 41, and is fastened to the valve hole formation body 2 at the protruding portion 451 using bolts B2. The solenoid core 44 and bracket 45 are fixed to the solenoid case 41 by crimping the open end of the solenoid case 41.

[0026] The plunger 46 is made of a soft magnetic material and is disposed at a position behind the solenoid core 44, Dr, when the electromagnetic coil 43 is de-energized. The plunger 46 is magnetically attracted toward the solenoid core 44 when the electromagnetic coil 43 is energized. A through-hole 461 penetrating the plunger 46 in the axial direction D is formed in the center of the plunger 46 when viewed from the axial direction D, and a shaft 47 is inserted and fitted into the through-hole 461. The shaft 47 is made of a non-magnetic material and moves axially together with the plunger 46 while pushing the spool 3 to move it axially. The shaft 47 is supported by the solenoid case 41 via a bush 13 so as to be slidable in the axial direction D, and is also supported by the solenoid core 44 via a bush 14 so as to be slidable in the axial direction D.

[0027] The front Df surface of the plunger 46 and the shaft 47 abuts against the solenoid core 44 via a front stopper 48, restricting movement of the plunger 46 and the shaft 47 in the forward direction Df, and the rear Dr surface of the plunger 46 abuts against the solenoid case 41 via a rear stopper 49, restricting movement of the plunger 46 in the rearward direction Dr. As the plunger 46 and the shaft 47 move, the spool 3 is pushed by the shaft 47 and moves in the axial direction. The spool 3 is disposed in front of the shaft 47 so that the ends of the spool 3 and the shaft 47 in the axial direction D abut against each other.

[0028] The spool 3 is formed in a shaft shape extending in the axial direction D, and is movable within an axial range between a forward end position where the plunger 46 abuts against the solenoid core 44 via a front stopper 48, and a reverse end position where the plunger 46 abuts against the solenoid case 41 via a rear stopper 49. Figures 1 and 3 show a state in which the spool 3 is in the forward end position below the central axis C of the spool 3, and a state in which the spool 3 is in the reverse end position above the central axis C.

[0029] The spool 3 has, in order from the rear end (Dr), a first land 31, a second land 32, a third land 33, and a fourth land 34. The first to fourth lands 31 to 34 are formed to protrude radially outward from adjacent portions of the spool 3 in the axial direction (D), and have cylindrical shapes with their outer surfaces formed straight along the axial direction (D). The first to third lands 31 to 33 have the same outer diameter, and the fourth land 34 has a smaller outer diameter than each of the first to third lands 31 to 33. Due to the difference in diameter between the third land 33 and the fourth land 34, when hydraulic oil is supplied into the valve hole 20 from the feedback port 24, the pressure of the hydraulic oil pushes the spool 3 toward the rear end (Dr).

[0030] The first land 31 opens and closes the first inter-port hole 25a in accordance with the movement of the spool 3. The second land 32 opens and closes the second inter-port hole 25b in accordance with the movement of the spool 3. The third land 33 opens and closes the third inter-port hole 25c in accordance with the movement of the spool 3, and continues to close the fourth inter-port hole 25d while the spool 3 is moving. The fourth land 34 continues to close the fifth inter-port hole 25e while the spool 3 is moving. As a result, as the spool 3 moves in the axial direction, the flow path areas between the first exhaust port 23a and the second exhaust port 23b, between the output port 22 and the second exhaust port 23b, and between the input port 21 and the output port 22 change sequentially, and the pressure of the hydraulic oil output from the output port 22 changes sequentially. The third land 33 and the fourth land 34 are blocking lands having portions that continue to block the inter-port holes as the spool 3 moves.

[0031] Fig. 4 is an enlarged view of a portion of Fig. 1 when the spool 3 is at the rear end position. Fig. 5 is an enlarged view of a portion of Fig. 1 when the spool 3 is at the forward end position.

[0032] Grooves 30 are formed on the outer periphery of the third land 33 at multiple locations in the axial direction D, along the circumferential direction of the spool 3. In this embodiment, four grooves 30 are formed on the outer periphery of the third land 33 at different positions in the axial direction D. The four grooves 30 are formed in a front region Df of the third land 33 and are equally spaced in the axial direction D. Each groove 30 is formed around the entire circumference of the third land 33. Hydraulic oil passing through a small gap between the outer periphery of the third land 33 and the inner periphery of the fourth inter-port hole 25d fills the grooves 30 all around. This equalizes the hydraulic pressure acting on the spool 3 from the hydraulic oil in the grooves 30 in the circumferential direction, thereby providing an alignment effect that suppresses eccentricity between the central axis C of the spool 3 and the central axis of the valve hole 20. Note that the grooves 30 may be formed intermittently in the circumferential direction, for example.

[0033] As shown in FIG. 4, when the spool 3 is at the rearward end position, the four grooves 30 formed in the third land 33 are contained within the fourth inter-port hole 25d. On the other hand, as shown in FIG. 5, when the spool 3 is at the forward end position, the entirety of one groove 30 located at the most forward position Df is exposed forward from the fourth inter-port hole 25d, and the entirety of each of the other three grooves 30 is contained within the fourth inter-port hole 25d. Of the four grooves 30 formed in the third land 33, the remaining three grooves 30, excluding the groove 30 located at the most forward position Df, are contained within the fourth inter-port hole 25d whether the spool 3 is at the forward end position or the rearward end position. In this specification, a blocking land in which the number of grooves 30 contained within the inter-port hole changes between when the spool 3 is at the forward end position and when the spool 3 is at the rearward end position, is referred to as a variable blocking land 300. In this embodiment, the third land is a variable blocking land 300. The advantages of providing the variable blocking land 300 will be described later.

[0034] A positioning portion 35 for positioning the biasing member 5 at the front Df is formed at the end of the spool 3 at the front Df. The positioning portion 35 includes a support portion 351 that protrudes outward and supports the biasing member 5 from the rear Dr, and a protrusion 352 that protrudes forward Df from the support portion 351. The protrusion 352 is inserted inside the biasing member 5 and positions the biasing member 5 in the radial direction. The biasing member 5 is made of a coil spring that can expand and contract in the axial direction D, and is disposed between the support portion 351 and the plug 11 in a compressed state in the axial direction D, regardless of whether the spool 3 is in the forward end position or the rearward end position. The biasing member 5 elastically biases the spool 3 toward the rear Dr by its restoring force.

[0035] (Spool valve 1 operation) Next, the operation of the spool valve 1 will be described. First, when the electromagnetic coil 43 is de-energized, the restoring force of the biasing member 5 maintains the spool 3 in the reverse end position, as shown in FIG. 1 . In this state, the third inter-port hole 25c is closed by the third land 33 of the spool 3, thereby disconnecting the input port 21 from the output port 22. A spool valve 1 in which communication between the input port 21 and the output port 22 is blocked when the electromagnetic solenoid 4 as an actuator is in an inactive state is called a normally closed spool valve. Furthermore, when the spool 3 is in the reverse end position, the first land 31 opens the first inter-port hole 25a, and the second land 32 opens the second inter-port hole 25b, thereby connecting the output port 22 to the first and second exhaust ports 23a and 23b. As a result, when the spool 3 is disposed at the reverse end position, the hydraulic oil is not output from the output port 22 to the output oil passage 12b.

[0036] 4, when the spool 3 is maintained in the reverse end position, the input port 21 side of the fourth inter-port hole 25d is the high-pressure side, and the feedback port 24 side is the low-pressure side. Due to this, unless some special ingenuity is taken, a force is generated in which the hydraulic oil pushes the third land 33 arranged in the fourth inter-port hole 25d in a direction perpendicular to the axial direction D, which may cause the spool 3 to become eccentric with respect to the valve hole 20, resulting in a fluid locking phenomenon. This phenomenon is likely to occur more noticeably when the fourth inter-port hole 25d is tapered and the side of the fourth inter-port hole 25d with a smaller flow path area is the high-pressure side (the input port 21 side) and the side of the fourth inter-port hole 25d with a larger flow path area is the low-pressure side (the feedback port 24 side).

[0037] In this embodiment, as described above, at least one of the first and second bolt holes 261, 262 is formed at a position closer to the input port 21 than the feedback port 24. Therefore, even if the inner circumferential surface of the fourth inter-port hole portion 25d is designed to be straight in the axial direction D, the axial force of the bolt B1 (see FIG. 3 ) applied when the valve hole formation body 2 is fastened to the transmission case 12 may cause the flow path area on the input port 21 side to become smaller and the flow path area on the feedback port 24 side to become larger. Alternatively, due to manufacturing precision of the valve hole 20, the flow path area of the fourth inter-port hole portion 25d on the input port 21 side may become smaller and the flow path area on the feedback port 24 side may become larger.

[0038] 4, in this embodiment, when the spool 3 is in the maximum reverse position, all of the grooves 30 formed in the third land 33 are configured to fit within the fourth inter-port hole 25d. This equalizes the hydraulic pressure acting on the spool 3 from the hydraulic oil in each groove 30 in the circumferential direction, providing an aligning effect that suppresses eccentricity between the central axis C of the spool 3 and the central axis of the valve hole 20, thereby preventing fluid sticking.

[0039] The fact that the occurrence of the fluid sticking phenomenon can be suppressed by providing a plurality of grooves 30 in the third land 33 will be described in more detail below. First, as shown in Figure 6, it is assumed that the inner circumferential surface of the fourth inter-port hole 25d is tapered so that the diameter decreases toward the high-pressure side in the axial direction D, and that no groove is formed in the third land 933. For convenience, in Figure 6, the inclination of the fourth inter-port hole 25d is exaggerated, and the gap between the inner circumferential surface of the fourth inter-port hole 25d and the third land 933 is also exaggerated.

[0040] 6, when the central axis C of the spool 3 is eccentric with respect to the central axis 20C of the valve hole 20, a relatively large amount of hydraulic oil enters the side of the third land 933 opposite the eccentricity, generating a force F1 that pushes the third land 933 toward the eccentric side. This increases the degree of eccentricity of the spool 3 with respect to the valve hole 20, and the third land 933 is pressed against the inner circumferential surface of the fourth inter-port hole 25d, potentially resulting in fluid locking. This phenomenon is unlikely to occur when the inner circumferential surface of the fourth inter-port hole 25d decreases in diameter toward the low-pressure side, but is more likely to occur when the inner circumferential surface of the fourth inter-port hole 25d decreases in diameter toward the high-pressure side.

[0041] Next, Fig. 7 shows an example (i.e., an example of this embodiment) in which multiple grooves 30 are provided in the third land 33, as compared to the state shown in Fig. 6. In the state shown in Fig. 7, hydraulic oil fills each groove 30 through a small gap between the outer peripheral surface of the third land 33 and the inner peripheral surface of the fourth inter-port hole 25d. This equalizes the force F2 acting on the spool 3 from the hydraulic oil in the grooves 30 in the circumferential direction, thereby providing an aligning effect that suppresses eccentricity between the central axis C of the spool 3 and the central axis 20C of the valve hole 20. It has been confirmed that this aligning effect is more pronounced when multiple grooves 30 are formed in the third land 33 than when a single wide groove is formed in the axial direction D.

[0042] As described above, when the spool 3 is in the rearward end position, all of the grooves 30 formed in the third land 33 are configured to fit within the fourth inter-port hole 25d, thereby effectively achieving the alignment effect.

[0043] When the spool 3 is in the rearward end position, energization of the electromagnetic coil 43 begins, generating a magnetic flux in a magnetic path including the solenoid core 44, the plunger 46, and the solenoid case 41 around the electromagnetic coil 43. This magnetic flux magnetically attracts the plunger 46 toward the solenoid core 44 (i.e., forward Df). Accordingly, the shaft 47, which moves axially together with the plunger 46, pushes the spool 3 forward Df against the biasing force of the biasing member 5, moving the spool 3 forward Df. As a result, as shown in FIG. 1 , the third land 33 opens the third inter-port hole 25c, thereby connecting the input port 21 and the output port 22. Furthermore, the first inter-port hole 25a is blocked by the first land 31, and the second inter-port hole 25b is blocked by the second land 32, blocking communication between the output port 22 and the first and second exhaust ports 23a and 23b. As a result, the hydraulic oil supplied to the input oil passage 12a is output to the output oil passage 12b through the input port 21, the third inter-port hole portion 25c, and the output port 22. As the third land 33 moves forward Df, the flow path area between the input port 21 and the output port 22 gradually increases, and the pressure of the hydraulic oil output from the output port 22 gradually increases.

[0044] A portion of the hydraulic oil output to the output oil passage 12b passes through the feedback oil passage 12c and is returned from the feedback port 24 to the valve hole 20. When the hydraulic oil flows from the feedback port 24 into the valve hole 20, a feedback force is generated, which is a force that the hydraulic oil pushes the spool valve 1 backward Dr. The spool 3 is positioned so that the magnetic attractive force generated between the plunger 46 and the solenoid balances with the biasing force and feedback force of the biasing member 5, depending on the value of the current passed through the electromagnetic coil 43. Therefore, by appropriately adjusting the value of the current passed through the electromagnetic coil 43, the position at which the magnetic attractive force balances with the biasing force and feedback force of the biasing member 5 can be adjusted, and the pressure of the hydraulic oil output from the output port 22 can be adjusted.

[0045] As described above, the feedback force affects the positioning of the spool 3 in the axial direction D, and therefore the pressure of the hydraulic oil output from the output port 22. However, hydraulic oil may leak from the input port 21 to the feedback port 24 through the small gap between the outer peripheral surface of the third land 33 and the inner peripheral surface of the fourth inter-port hole 25d. If this leakage amount becomes excessive, the feedback force becomes larger than the desired value. This may cause the position of the spool 3 in the axial direction D to deviate from the desired position, and the pressure of the hydraulic oil output from the output port 22 to deviate significantly from the desired value. The amount of hydraulic oil leaking from the input port 21 to the feedback port 24 increases as the number of grooves 30 accommodated in the fourth inter-port hole 25d increases. This is because the opposing area between the outer peripheral surface of the third land 33 (excluding the portion where the grooves 30 are formed) and the fourth inter-port hole 25d decreases as the number of grooves 30 accommodated in the fourth inter-port hole 25d increases.

[0046] 5, in this embodiment, when the spool 3 is in the forward end position, the entirety of one of the four grooves 30, which is located most forward (Df), is exposed forward (Df) from the fourth inter-port hole 25d. Therefore, as the spool 3 moves from the reverse end position to the forward end position, the groove 30 formed at the end of the forward (Df) is gradually exposed from the fourth inter-port hole 25d, and a portion of the third land 33 at the rear (Dr) is inserted into the fourth inter-port hole 25d relative to the groove 30 formed at the end of the rear (Dr). Therefore, as the spool 3 moves from the reverse end position to the forward end position, the opposing area between the outer circumferential surface of the third land 33 and the fourth inter-port hole 25d increases, reducing the amount of hydraulic oil leaking from the input port 21 to the feedback port 24. This prevents the axial position (D) of the spool 3 from deviating from the desired position, making it easier to maintain the hydraulic pressure of the hydraulic oil output from the output port 22 at a desired value.

[0047] (Functions and Effects of the First Embodiment) In this embodiment, the number of grooves 30 of the third land 33 (variably blocking land 300) accommodated within the fourth inter-port hole 25d varies between when the spool 3 is positioned at one end of its axial range and when the spool 3 is positioned at the other end of its axial range. Therefore, when an alignment effect is desired (when the spool 3 is at the extreme reverse position in this embodiment), the alignment effect can be effectively achieved by increasing the number of grooves 30 of the third land 33 accommodated within the fourth inter-port hole 25d. On the other hand, when leakage amount is desired to be suppressed (when the input port 21 and the output port 22 are in communication in this embodiment), the amount of hydraulic oil leakage from the input port 21 to the feedback port 24 can be suppressed by reducing the number of grooves 30 of the third land 33 accommodated within the fourth inter-port hole 25d. In other words, in this embodiment, the alignment effect and the leakage amount suppression effect can be efficiently obtained when needed.

[0048] Furthermore, whether the spool 3 is positioned at one end of its axial range or the other end of its axial range, the plurality of (preferably three or more, but may be two or more) grooves 30 of the third land 33 are contained within the fourth inter-port hole 25d. Therefore, even if the spool 3 is maintained at the forward end position for a long period of time, for example, the plurality of grooves 30 of the third land 33 are contained within the fourth inter-port hole 25d, making it easy to achieve an alignment effect.

[0049] Furthermore, the number of grooves 30 contained within the fourth inter-port hole 25d located between the input port 21 and the feedback port 24 is greater when the third land 33 closes the third inter-port hole 25c located between the input port 21 and the output port than when the third land 33 opens the third inter-port hole 25c. When the third land 33 closes the third inter-port hole 25c (for example, when the spool 3 is at the reverse end position), the pressure difference between the input port 21 and the feedback port 24 increases, making the aligning effect particularly important. On the other hand, when the third land 33 opens the third inter-port hole 25c (for example, when the spool 3 is at the forward end position), it is particularly important to suppress the amount of hydraulic oil flowing from the input port 21 to the feedback port 24 in order to obtain the desired feedback force, as described above. Therefore, when the input port 21 and the output port 22 are not connected, the number of grooves of the third land 33 that fit within the fourth inter-port hole portion 25d is increased, and when the input port 21 and the output port 22 are connected, the number of grooves of the third land 33 that fit within the fourth inter-port hole portion 25d is decreased, thereby making it possible to efficiently obtain the alignment effect and the effect of suppressing the amount of leakage when needed.

[0050] Furthermore, for at least one of the first and second bolt holes 261, 262, the shortest distance to the input port 21 is shorter than the shortest distance to the feedback port 24. Therefore, the axial force of the bolt B1 when the valve-hole formation body 2 is fastened to the transmission case 12 can deform the inner circumferential surface of the fourth inter-port hole 25d so that the diameter decreases toward the input port 21. When the inner circumferential surface of the fourth inter-port hole 25d is deformed in this manner, the pressure difference between the input port 21 and the feedback port 24 across the fourth inter-port hole 25d increases when the third inter-port hole 25c is closed, making it more likely that fluid will stick, as described above. Therefore, in this embodiment, when the third inter-port hole 25c is closed, a relatively large number of grooves 30 are accommodated in the fourth inter-port hole 25d, thereby suppressing the occurrence of fluid sticking, even in a state in which fluid sticking is more likely to occur.

[0051] As described above, according to this embodiment, it is possible to provide a spool valve that can efficiently obtain the effects of alignment and suppression of leakage amount.

[0052] [Second embodiment] Fig. 8 is a cross-sectional view of the spool valve 1 in this embodiment. Fig. 9 is an enlarged view of a portion of Fig. 8 when the spool 3 is in the rearward end position. Fig. 10 is an enlarged view of a portion of Fig. 8 when the spool 3 is in the forward end position. Fig. 8 shows a state in which the spool 3 is in the forward end position below the central axis C, and a state in which the spool 3 is in the rearward end position above the central axis C of the spool 3.

[0053] In this embodiment, the valve hole formation body 2 is configured by a sleeve. The sleeve is separate from the valve body attached to the transmission case and is inserted into the valve body. The valve hole formation body 2 is provided with, in order from the rear Dr, a first exhaust port 23a, a feedback port 24, an input port 21, an output port 22, a second exhaust port 23b, and a third exhaust port 23c.

[0054] In this embodiment, the valve hole formation body 2 has, in order from the rear end Dr in the axial direction D, a first inter-port hole portion 25a, a second inter-port hole portion 25b, a third inter-port hole portion 25c, a fourth inter-port hole portion 25d, and a fifth inter-port hole portion 25e. The first inter-port hole portion 25a is located between the first exhaust port 23a and the feedback port 24. The second inter-port hole portion 25b is located between the feedback port 24 and the input port 21. The third inter-port hole portion 25c is located between the input port 21 and the output port 22. The fourth inter-port hole portion 25d is located between the output port 22 and the second exhaust port 23b. The fifth inter-port hole portion 25e is located between the second exhaust port 23b and the third exhaust port 23c.

[0055] The spool 3 is formed with a first land 31, a second land 32, and a third land 33, in that order from the rear Dr. The first and second lands 31, 32 have the same outer diameter, and the third land 33 has a smaller outer diameter than the first and second lands 31, 32. Due to the difference in diameter between the first land 31 and the second land 32, when hydraulic oil is supplied from the feedback port 24 into the valve hole 20, the pressure of the hydraulic oil pushes the spool 3 forward Df.

[0056] The first land 31 continues to close the first inter-port hole 25a while the spool 3 moves. The second land 32 continues to close the second inter-port hole 25b while the spool 3 moves, and opens and closes the third inter-port hole 25c as the spool 3 moves. The third land 33 opens and closes the fourth inter-port hole 25d as the spool 3 moves, and continues to close the fifth inter-port hole 25e while the spool 3 moves. As a result, the flow path areas between the input port 21 and the output port 22 and between the output port 22 and the second discharge port 23b change sequentially as the spool 3 moves in the axial direction, and the pressure of the hydraulic oil output from the output port 22 changes sequentially. The first to third lands 31 to 33 are closed lands having portions that continue to close the inter-port holes as the spool 3 moves.

[0057] Grooves 30 are formed on the outer periphery of the second land 32 at four locations in the axial direction D, along the circumferential direction of the spool 3. In this embodiment, the four grooves 30 are formed on the outer periphery of the second land 32 at different positions in the axial direction D. The four grooves 30 are formed in a rear region Dr of the second land 32 and are equally spaced in the axial direction D. Each groove 30 is formed around the entire circumference of the second land 32. Hydraulic oil passing through a small gap between the outer periphery of the second land 32 and the inner periphery of the second inter-port hole 25b fills the entire grooves 30. This equalizes the hydraulic pressure acting on the spool 3 from the hydraulic oil in the grooves 30 in the circumferential direction, providing an alignment effect that suppresses eccentricity between the central axis C of the spool 3 and the central axis of the valve hole 20.

[0058] As shown in Fig. 9, when the spool 3 is at the rearmost drive position, the entirety of one groove 30 located at the rearmost drive direction (Dr) is exposed to the rearward drive direction through the second inter-port hole 25b, and the entirety of each of the other three grooves 30 is contained within the second inter-port hole 25b. On the other hand, as shown in Fig. 10, when the spool 3 is at the forward drive position, the four grooves 30 formed in the second land 32 are contained within the second inter-port hole 25b. Of the four grooves 30 formed in the second land 32, three grooves 30 excluding the groove 30 located at the rearmost drive direction (Dr) are contained within the second inter-port hole 25b whether the spool 3 is at the forward drive position or the rearward drive position. That is, in this embodiment, the second land 32 is a variable blocking land 300.

[0059] The spool valve 1 of this embodiment does not have the bracket (see reference numeral 45 in FIGS. 1 and 3) described in the first embodiment. In this embodiment, the open end of the solenoid case 41 is crimped to the solenoid core 44 and the valve hole formation body 2, thereby fixing the solenoid case 41, the solenoid core 44, and the valve hole formation body 2.

[0060] (Spool valve 1 operation) Next, the operation of the spool valve 1 will be described. First, as shown in FIG. 8 , when the electromagnetic coil 43 is de-energized, the restoring force of the biasing member 5 maintains the spool 3 in the reverse end position. In this state, the third inter-port hole 25c is opened by the second land 32 of the spool 3, thereby communicating between the input port 21 and the output port 22. When the spool 3 is in the reverse end position, the third land 33 closes the fourth inter-port hole 25d, thereby blocking communication between the output port 22 and the second exhaust port 23b. As a result, hydraulic oil supplied from the input port 21 to the valve bore 20 passes through the input port 21 and the third inter-port hole 25c and is output from the output port 22. A spool valve 1 in which communication between the input port 21 and the output port 22 is maintained when the electromagnetic solenoid 4 serving as the actuator is in a non-operating state is called a normally open spool valve.

[0061] A portion of the hydraulic oil output from the output port 22 is returned to the valve hole 20 through the feedback port 24. The hydraulic oil flowing into the valve hole 20 from the feedback port 24 generates a feedback force, which is a force that pushes the spool valve 1 forward Df. The spool 3 is positioned so that the magnetic attractive force and feedback force generated between the plunger 46 and the solenoid and the biasing force of the biasing member 5 are balanced according to the value of the current passed through the electromagnetic coil 43. Therefore, by appropriately adjusting the value of the current passed through the electromagnetic coil 43, the position where the magnetic attractive force and feedback force and the biasing force of the biasing member 5 are balanced can be adjusted, and the pressure of the hydraulic oil output from the output port 22 can be adjusted.

[0062] As described above, the feedback force affects the positioning of the spool 3 in the axial direction D, and therefore the pressure of the hydraulic oil output from the output port 22. However, hydraulic oil may leak from the input port 21 to the feedback port 24 through the small gap between the outer circumferential surface of the second land 32 and the inner circumferential surface of the second inter-port hole 25b. If this leakage amount becomes excessive, the feedback force becomes larger than the desired value. This may cause the position of the spool 3 in the axial direction D to deviate from the desired position, and the pressure of the hydraulic oil output from the output port 22 to deviate significantly from the desired value. The amount of hydraulic oil leaking from the input port 21 to the feedback port 24 increases as the number of grooves 30 accommodated in the second inter-port hole 25b increases. This is because the opposing area between the outer circumferential surface of the second land 32 (excluding the portion where the grooves 30 are formed) and the second inter-port hole 25b decreases as the number of grooves 30 accommodated in the second inter-port hole 25b increases.

[0063] 9, in this embodiment, when the spool 3 is in the reverse end position, the entirety of one of the four grooves 30, which is located furthest rearward (Dr), is exposed to the rearward (Dr) from the second inter-port hole 25b. Therefore, when the spool 3 is in the reverse end position, a sufficient opposing area is ensured between the outer circumferential surface of the second land 32 and the inner circumferential surface of the second inter-port hole 25b, reducing the amount of hydraulic oil leaking from the input port 21 to the feedback port 24. This prevents the position of the spool 3 in the axial direction D from shifting from the desired position, making it easier to maintain the hydraulic pressure of the hydraulic oil output from the output port 22 at a desired value.

[0064] When the spool 3 is in the reverse end position, energization of the electromagnetic coil 43 begins, generating a magnetic flux in a magnetic path including the solenoid core 44, the plunger 46, and the solenoid case 41 around the electromagnetic coil 43. This magnetic flux magnetically attracts the plunger 46 toward the solenoid core 44 (i.e., forward Df). Accordingly, the shaft 47, which moves axially together with the plunger 46, pushes the spool 3 forward Df against the biasing force of the biasing member 5, moving the spool 3 forward. As a result, as shown in FIG. 8 , the second land 32 closes the third inter-port hole 25c, blocking communication between the input port 21 and the output port 22. At the same time, the third land 33 opens the fourth inter-port hole 25d, connecting the output port 22 and the second discharge port 23b. As a result, when the spool 3 is in the forward end position, hydraulic oil is not output from the output port 22.

[0065] 10, when the spool 3 is maintained in the forward end position, the input port 21 of the second inter-port hole 25b is the high-pressure side, and the feedback port 24 side is the low-pressure side. Due to this, unless some special ingenuity is taken, a force is generated in which the hydraulic oil pushes the second land 32 arranged in the second inter-port hole 25b in a direction perpendicular to the axial direction D, which may cause the spool 3 to become eccentric with respect to the valve hole 20, resulting in a fluid locking phenomenon. This phenomenon is likely to occur more noticeably when the second inter-port hole 25b is tapered and the side of the second inter-port hole 25b with a smaller flow path area is the high-pressure side (the input port 21 side) and the side of the second inter-port hole 25b with a larger flow path area is the low-pressure side (the feedback port 24 side).

[0066] Therefore, in this embodiment, when the spool 3 is at the forward end position, all of the grooves 30 formed in the second land 32 are configured to fit within the second inter-port hole 25b. This equalizes the hydraulic pressure acting on the spool 3 from the hydraulic oil in each groove 30 in the circumferential direction, providing an aligning effect that suppresses eccentricity between the central axis C of the spool 3 and the central axis of the valve hole 20, thereby preventing fluid sticking.

[0067] The rest is the same as in the first embodiment. It should be noted that, among the symbols used in the second and subsequent embodiments, the same symbols as those used in the previously described embodiments represent the same components, etc. as those in the previously described embodiments, unless otherwise specified.

[0068] (Functions and Effects of the Second Embodiment) This embodiment also has the same effects as the first embodiment.

[0069] (Addendum) Although the present invention has been described above based on the embodiments, the invention according to the claims is not limited to these embodiments. It should be noted that not all of the combinations of features described in the embodiments are necessarily essential to the means for solving the problems of the invention.

[0070] Furthermore, the present invention can be implemented in various ways, such as by omitting some components or adding or substituting components, without departing from the spirit of the invention.

[0071] In each of the above embodiments, the spool valve is an electromagnetic valve, but the present invention is not limited to this. For example, the spool may be moved axially by an actuator such as a motor. [Explanation of symbols]

[0072] 1... Spool valve 2... Valve hole formation body 20...Valve hole 21...Input port 22...Output port 23a...First discharge port 23b...Second discharge port 23c...Third discharge port 24...Feedback port 25a...First inter-port hole portion 25b... second inter-port hole portion 25c... third inter-port hole portion 25d...Fourth port hole portion 25e...Fifth port hole portion 261...First bolt hole 262...Second bolt hole 3...Spool 30...Groove 300...Variable Blockage Land 31...First Land 32...Second Land 33...Third Land 34...4th land 4...Electromagnetic solenoid (actuator) 5... Urging member B1... Bolt D…Axis direction

Claims

1. a valve hole forming body having a valve hole formed in an axial direction and a plurality of ports formed at a plurality of locations in the axial direction to open the valve hole to the outer circumferential side; a spool movable within a predetermined axial range within the valve hole, the spool has at least one blocking land having a portion that continues to block an inter-port hole portion of the valve hole located between two adjacent ports during movement from one end to the other end of the axial range, at least one of the occluding lands is a variable occluding land; The variable blocking land has grooves formed at a plurality of locations in the axial direction on its outer periphery, the grooves extending in the circumferential direction of the spool, the number of grooves of the variable blockage land that fit within the port bore varies between when the spool is at one end of the axial range and when the spool is at the other end of the axial range; the plurality of grooves of the variable blocking land are contained within the inter-port bore when the spool is positioned at one end of the axial range and when the spool is positioned at the other end of the axial range. Spool valve.

2. a valve hole forming body having a valve hole formed in an axial direction and a plurality of ports formed at a plurality of locations in the axial direction to open the valve hole to the outer circumferential side; a spool movable within a predetermined axial range within the valve hole, the spool has at least one blocking land having a portion that continues to block an inter-port hole portion of the valve hole located between two adjacent ports during movement from one end to the other end of the axial range, at least one of the occluding lands is a variable occluding land; The variable blocking land has grooves formed at a plurality of locations in the axial direction on its outer periphery, the grooves extending in the circumferential direction of the spool, the number of grooves of the variable blockage land that fit within the port bore varies between when the spool is at one end of the axial range and when the spool is at the other end of the axial range; the valve orifice formation body has an input port which is the port for inputting hydraulic oil into the valve orifice, an output port which is the port for outputting hydraulic oil from the valve orifice, and a feedback port which is the port for returning a portion of the hydraulic oil output from the output port to the valve orifice, the variable blocking land opens and closes the inter-port hole located between the input port and the output port in accordance with axial movement of the spool, and continues to block the inter-port hole located between the input port and the feedback port while the spool moves from one end to the other end of the axial range; a number of the grooves contained in the inter-port hole located between the input port and the feedback port is greater when the variable blocking land blocks the inter-port hole located between the input port and the output port than when the variable blocking land opens the inter-port hole located between the input port and the output port; Spool valve.

3. the valve orifice formation body has an input port which is the port for inputting hydraulic oil into the valve orifice, an output port which is the port for outputting hydraulic oil from the valve orifice, and a feedback port which is the port for returning a portion of the hydraulic oil output from the output port to the valve orifice, the variable blocking land opens and closes the inter-port hole located between the input port and the output port in accordance with axial movement of the spool, and continues to block the inter-port hole located between the input port and the feedback port while the spool moves from one end to the other end of the axial range; a number of the grooves contained in the inter-port hole located between the input port and the feedback port is greater when the variable blocking land blocks the inter-port hole located between the input port and the output port than when the variable blocking land opens the inter-port hole located between the input port and the output port; 2. The spool valve of claim 1.

4. a biasing member that biases the spool toward one axial side; an actuator that moves the spool toward the other axial side against the biasing force of the biasing member, the variably closing land closes the inter-port hole located between the input port and the output port when the actuator is not in operation, and opens the inter-port hole located between the input port and the output port when the actuator is in operation.

4. A spool valve according to claim 2 or 3.

5. a biasing member that biases the spool toward one axial side; an actuator that moves the spool toward the other axial side against the biasing force of the biasing member, the variably closing land opens the inter-port hole located between the input port and the output port when the actuator is not in operation, and closes the inter-port hole located between the input port and the output port when the actuator is in operation.

4. A spool valve according to claim 2 or 3.

6. The valve hole formation body has a plurality of bolt holes formed in a direction intersecting the axial direction for inserting or screwing bolts for attaching the valve hole formation body to an attachment object, a shortest distance between at least one of the plurality of bolt holes and the input port is shorter than a shortest distance between at least one of the plurality of bolt holes and the feedback port; A spool valve according to any one of claims 2 to 5.

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