Hydraulic valve

Abstract

To provide a hydraulic valve that can improve responsiveness while ensuring stability. [Solution] The hydraulic valve 2 comprises a solenoid, a sleeve 4 having a spool hole 41, a spool 5 that moves along the axial direction of the spool hole 41 in response to the thrust applied by the solenoid, and a biasing spring 6 that biases the spool 5 toward its initial position. The sleeve 4 has a supply port 42, a connection port 43, and a tank port 44. The spool 5 has a first oil passage 51 formed extending axially inside the spool 5, and a second oil passage 52 that connects the first oil passage 51 and the spool hole 41. When the connection port 43 communicates with the tank port 44, the hydraulic fluid discharged from the actuator and passing through the connection port 43 flows through the second oil passage 52 into the first oil passage 51, applying additional thrusts F1 and F2 to the spool 5 that move the spool 5 toward its initial position.

Description

Technical Field

[0001] The present invention relates to a hydraulic valve that controls the flow direction and flow rate of hydraulic oil by the operation of a spool.

Background Art

[0002] For example, in the gear shift of a tractor or the like, in many cases, an electromagnetic proportional valve mounted on a hydraulic valve is adopted as a control valve for switching a clutch. The electromagnetic proportional valve has a role of converting an electric signal sent from an operator into a hydraulic signal. The switching timing of clutches such as the main gear shift and the auxiliary gear shift affects the shock of the machine equipped with the clutch. Therefore, the responsiveness of the electromagnetic proportional valve is very important.

[0003] Here, Patent Document 1 discloses a hydraulic pilot-type electromagnetic proportional control valve that controls the flow direction and flow rate of hydraulic oil. Further, Patent Document 2 discloses a spool valve structure applied as a residual pressure release valve in a clutch hydraulic control circuit of a vehicle automatic transmission.

[0004] However, as described in Patent Document 1 and Patent Document 2, the stability and responsiveness of the operation of the electromagnetic proportional valve are in a trade-off relationship with each other. Therefore, there is a problem that it is difficult to achieve both stability and responsiveness in the electromagnetic proportional valve. Generally, stability is more important than responsiveness, and stability is ensured. Therefore, for example, there is a problem that the responsiveness when releasing the pressure of the clutch, that is, the responsiveness when returning the spool of the hydraulic valve to the initial position, is not sufficient for the requirements. Improvement of the responsiveness of the hydraulic valve is desired.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

[0006] This invention has been made in view of the above circumstances, and aims to provide a hydraulic valve that can improve responsiveness while ensuring stability. [Means for solving the problem]

[0007] One aspect of the present invention comprises a solenoid that converts electrical energy into mechanical energy of linear motion, a sleeve fixed to the solenoid and having a spool hole extending in the direction of the linear motion, a spool disposed inside the spool hole and moving along the axial direction of the spool hole in response to the thrust applied by the solenoid, and a biasing spring sandwiched between the sleeve and the spool and biasing the spool toward its initial position, wherein the sleeve has a supply port through which hydraulic fluid supplied from a hydraulic pump passes, and the hydraulic fluid and the The hydraulic valve has a connection port through which the hydraulic fluid discharged from the actuator passes, and a tank port through which the hydraulic fluid led to the tank passes, and the spool has a first oil passage formed inside the spool extending along the axial direction, and a second oil passage connecting the first oil passage and the spool hole, and when the connection port communicates with the tank port, the hydraulic fluid discharged from the actuator and passing through the connection port passes through the second oil passage and flows into the first oil passage, providing the spool with an additional thrust that moves the spool in the direction of the initial position. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a hydraulic valve that can improve responsiveness while ensuring stability. [Brief explanation of the drawing]

[0009] [Figure 1]This is a cross-sectional view showing a hydraulic valve according to this embodiment. [Figure 2] This is a cross-sectional view showing the sleeve of this embodiment. [Figure 3] This is a cross-sectional view showing the spool of this embodiment. [Figure 4] This is a cross-sectional view showing the connection port in communication with the supply port. [Figure 5] This is a cross-sectional view showing the state in which the first notch engages with the inner wall of the spool hole. [Figure 6] This is a cross-sectional view showing a state where the connection port is not in communication with the supply port and the tank port. [Figure 7] This is a cross-sectional view showing the second notch engaging with the inner wall of the spool hole. [Figure 8] This is a cross-sectional view showing the connection port in communication with the tank port. [Modes for carrying out the invention]

[0010] Embodiments of the present invention will be described below with reference to the drawings. The embodiments described below are preferred examples of the present invention and are subject to various technically preferred limitations. However, the scope of the present invention is not limited to these embodiments unless otherwise stated in the following description. In addition, similar components are denoted by the same reference numerals in the drawings, and detailed descriptions are omitted as appropriate.

[0011] Figure 1 is a cross-sectional view showing a hydraulic valve according to this embodiment. Figure 2 is a cross-sectional view showing the sleeve of this embodiment. Figure 3 is a cross-sectional view showing the spool of this embodiment.

[0012] As shown in Figure 1, the hydraulic valve 2 according to this embodiment comprises a solenoid 3, a sleeve 4, a spool 5, and a biasing spring 6.

[0013] The solenoid 3 has a case 31, a coil 32, a plunger 33, a base 34, and a push pin 35. The case 31 houses the coil 32 and the plunger 33. Also, the case 31 houses at least a part of the base 34 and at least a part of the push pin 35.

[0014] At least a part of the plunger 33 is disposed inside the coil 32. The plunger 33 is magnetized by the magnetic field generated in the coil 32 when current flows through the conductor of the coil 32, and moves along the central axis of the coil 32. At least a part of the base 34 is disposed inside the coil 32. The base 34 is fixed to the case 31 and is magnetized by the magnetic field generated in the coil 32 when current flows through the conductor of the coil 32. Unlike the plunger 33, the base 34 does not move along the central axis of the coil 32.

[0015] The push pin 35 is fixed to the plunger 33 and moves along the central axis of the coil 32 together with the plunger 33 as the plunger 33 moves. Also, the push pin 35 is connected to the spool 5 at one end.

[0016] When current flows through the conductor of the coil 32, the plunger 33 and the base 34 are magnetized by the magnetic field generated in the coil 32 and attract each other. The plunger 33 receives a force in the direction in which the plunger 33 and the base 34 attract each other, and moves toward the base 34 along the central axis of the coil 32. Thereby, the plunger 33 applies a thrust to the spool 5 via the push pin 35 and moves the spool 5. Thus, the solenoid 3 converts electrical energy into mechanical energy of linear motion.

[0017] The thrust generated in the solenoid 3 changes according to the current value flowing through the conductor of the coil 32. Specifically, when the current value flowing through the conductor of the coil 32 is relatively large, the thrust generated in the solenoid 3 is relatively large.

[0018] As shown in FIG. 1, the sleeve 4 is fixed to the base 34 of the solenoid 3. As shown in FIG. 2, the sleeve 4 has a substantially cylindrical shape and has a spool hole 41 formed therein. The spool hole 41 extends in the direction of the linear motion generated by the solenoid 3, that is, the moving direction of the plunger 33, and penetrates the sleeve 4 in the axial direction (that is, the moving direction of the plunger 33).

[0019] The sleeve 4 has a supply port 42, a connection port 43, and a tank port 44. The supply port 42 penetrates the sleeve 4 in the radial direction. That is, the supply port 42 communicates the spool hole 41 formed inside the sleeve 4 with the outside of the sleeve 4. The supply port 42 is connected to the pump oil passage 91 (see FIGS. 4 to 8), and guides the hydraulic oil supplied from a hydraulic pump (not shown) through the pump oil passage 91 to the spool hole 41. That is, the hydraulic oil supplied from the hydraulic pump flows through the pump oil passage 91, passes through the supply port 42, and is guided to the spool hole 41.

[0020] The connection port 43 penetrates the sleeve 4 in the radial direction. That is, the connection port 43 communicates the spool hole 41 formed inside the sleeve 4 with the outside of the sleeve 4. The connection port 43 is connected to the actuator oil passage 92 (see FIGS. 4 to 8), and guides the hydraulic oil supplied from the hydraulic pump through the supply port 42 to an actuator (not shown). That is, the hydraulic oil sent to the actuator passes through the connection port 43, flows through the actuator oil passage 92, and is guided to the actuator. Further, the connection port 43 guides the hydraulic oil discharged from the actuator to the spool hole 41. That is, the hydraulic oil discharged from the actuator flows through the actuator oil passage 92, passes through the connection port 43, and is guided to the spool hole 41.

[0021] The tank port 44 penetrates the sleeve 4 radially. That is, the tank port 44 connects the spool hole 41 formed inside the sleeve 4 to the outside of the sleeve 4. The tank port 44 is connected to the tank oil passage 93 (see Figures 4 to 8), and guides the hydraulic fluid discharged from the actuator through the connection port 43 to a tank (not shown), such as a transmission case mounted on industrial machinery. In other words, the hydraulic fluid discharged to the tank passes through the tank port 44, flows through the tank oil passage 93, and is guided to the tank.

[0022] The sleeve 4 further has a groove 48. The groove 48 is formed as a recess extending radially inward from the outer circumferential surface of the sleeve 4. As shown in Figure 1, the O-ring 49 is fitted into the groove 48 of the sleeve 4.

[0023] As shown in Figure 1, at least a portion of the spool 5 is located inside the spool hole 41. As shown in Figure 3, the spool 5 has a substantially cylindrical shape and has a first oil passage 51 formed inside. The first oil passage 51 extends in the axial direction of the spool hole 41 (i.e., the direction of movement of the plunger 33). The first oil passage 51 is closed at one end 58 of the spool 5. The one end 58 is the end of the spool 5 in the direction of the initial position of the spool 5. Details of the initial position of the spool 5 will be described later. On the other hand, the first oil passage 51 is open at the other end 59 of the spool 5. The other end 59 is the end of the spool 5 in the direction opposite to the direction of the initial position of the spool 5.

[0024] The spool 5 further includes a second oil passage 52 and a third oil passage 56. The second oil passage 52 penetrates the spool 5 radially. That is, the second oil passage 52 connects the first oil passage 51, which is formed inside the spool 5, with the outside of the spool 5. The third oil passage 56, similar to the second oil passage 52, penetrates the spool 5 radially and connects the first oil passage 51, which is formed inside the spool 5, with the outside of the spool 5.

[0025] The spool 5 moves along the axial direction of the spool hole 41 in response to the thrust applied by the solenoid 3. Specifically, the push pin 35 of the solenoid 3 is connected to one end 58 of the spool 5, transmitting the thrust generated in the solenoid 3 to the spool 5. The spool 5 moves along the axial direction of the spool hole 41 (i.e., the direction of movement of the plunger 33) in response to the thrust applied from the plunger 33 via the push pin 35. At this time, the outer circumferential surface of the spool 5 slides against the inner wall surface of the spool hole 41.

[0026] The spool 5 has a first land portion 53, a second land portion 54, and a third land portion 55. The first land portion 53 protrudes radially outward from a first rod portion 571 provided between the first land portion 53 and the third land portion 55. The first land portion 53 is fitted into the spool hole 41 so as to be movable along the axial direction of the spool hole 41. That is, the outer circumferential surface of the first land portion 53 slides against the inner wall surface of the spool hole 41. By moving along the axial direction of the spool hole 41, the first land portion 53 has a valve function that sets the supply port 42 and the connection port 43 to communicate with each other, or sets the supply port 42 and the connection port 43 to be disconnected from each other.

[0027] The second land portion 54 protrudes radially outward from the second rod portion 572, which is provided between the second land portion 54 and the third land portion 55. The second land portion 54 is provided apart from the first land portion 53 in the axial direction of the spool 5 (i.e., the axial direction of the spool hole 41), and is fitted into the spool hole 41 so as to be movable along the axial direction of the spool hole 41. That is, the outer circumferential surface of the second land portion 54 slides against the inner wall surface of the spool hole 41. By moving along the axial direction of the spool hole 41, the second land portion 54 has a valve function that sets the connection port 43 and the tank port 44 to communicate with each other, or sets the connection port 43 and the tank port 44 to be disconnected from each other.

[0028] The third land portion 55 is provided between the first land portion 53 and the second land portion 54, and protrudes radially outward from the first rod portion 571 and the second rod portion 572. The third land portion 55 is fitted into the spool hole 41 so as to be movable along the axial direction of the spool hole 41. That is, the outer circumferential surface of the third land portion 55 slides against the inner wall surface of the spool hole 41.

[0029] The aforementioned second oil passage 52 penetrates the third land portion 55 radially through the spool 5. As the third land portion 55 moves along the axial direction of the spool hole 41, the outer opening of the second oil passage 52 is either closed or left open by the sleeve 4 (specifically, the inner wall surface of the spool hole 41).

[0030] The diameter D1 of the first land portion 53 is smaller than the diameter D2 of the second land portion 54, and larger than the diameter D3 of the first rod portion 571 and the diameter D4 of the second rod portion 572. The diameter D2 of the second land portion 54 is larger than the diameter D1 of the first land portion, and larger than the diameter D3 of the first rod portion 571 and the diameter D4 of the second rod portion 572.

[0031] As shown in Figure 3, the first land portion 53 has a first notch 531, a first outer peripheral surface 532, and a first wall surface 533. The first wall surface 533 rises radially outward from the first rod portion 571 and faces the second land portion 54 and the third land portion 55. The first notch 531 is formed in a groove shape at the boundary between the first wall surface 533 and the first outer peripheral surface 532. The first land portion 53 in this embodiment has a plurality of first notches 531. The plurality of first notches 531 are spaced apart from each other and are evenly distributed in the circumferential direction of the first land portion 53.

[0032] The second land portion 54 has a second notch 541, a second outer peripheral surface 542, and a second wall surface 543. The second wall surface 543 rises radially outward from the second rod portion 572 and faces the first land portion 53 and the third land portion 55. The second notch 541 is formed in a groove shape at the boundary between the second wall surface 543 and the second outer peripheral surface 542. The second land portion 54 in this embodiment has a plurality of second notches 541. The plurality of second notches 541 are spaced apart from each other and are evenly distributed in the circumferential direction of the second land portion 54.

[0033] The biasing spring 6 is positioned between the sleeve 4 and the spool 5. Specifically, the biasing spring 6 is sandwiched between one end 45 of the sleeve 4 and a flange portion 581 provided on one end 58 of the spool 5. The flange portion 581 protrudes radially outward from the outer circumferential surface of the spool 5 at one end 58 of the spool 5.

[0034] The biasing spring 6 biases the spool 5 in the direction of the initial position. In this specification, "initial position" refers to the position where the spool 5 is located when no current is flowing through the conductor of the coil 32, that is, when no magnetic field is generated in the coil 32 and the plunger 33 and base 34 are not magnetized. Therefore, "direction of the initial position" corresponds to the left direction in Figures 1 to 3. In other words, the biasing spring 6 biases the spool 5 to the left in Figures 1 to 3.

[0035] Next, the operation of the hydraulic valve 2 according to this embodiment will be described with reference to the drawings. Figure 4 is a cross-sectional view showing the connection port in communication with the supply port. Figure 5 is a cross-sectional view showing the state in which the first notch engages with the inner wall of the spool hole. Figure 6 is a cross-sectional view showing a state where the connection port is not in communication with the supply port and the tank port. Figure 7 is a cross-sectional view showing the state in which the second notch engages with the inner wall of the spool hole. Figure 8 is a cross-sectional view showing the connection port in communication with the tank port.

[0036] As shown in Figures 4 to 8, the hydraulic valve 2 according to this embodiment is inserted into and fixed in the valve block 9. Specifically, the sleeve 4 of the hydraulic valve 2 is inserted into the valve block 9 and fixed inside the valve block 9 via an O-ring 49.

[0037] The valve block 9 has a pump oil passage 91, an actuator oil passage 92, and a tank oil passage 93. The pump oil passage 91 leads hydraulic fluid supplied from a hydraulic pump (not shown) to the supply port 42 of the sleeve. The actuator oil passage 92 leads hydraulic fluid supplied through the connection port 43 of the sleeve 4 to the actuator. The actuator oil passage 92 also leads hydraulic fluid discharged from the actuator to the connection port 43 of the sleeve 4. The tank oil passage 93 leads hydraulic fluid discharged through the tank port 44 of the sleeve 4 to the tank.

[0038] For example, when pressure is applied to the actuator, such as when engaging a clutch, the control unit (not shown) increases the current flowing through the wires of the coil 32. As a result, as shown in Figure 4, the spool 5 moves in the opposite direction to its initial position (to the right in Figure 4) in response to the thrust applied from the plunger 33 via the push pin 35, while resisting the biasing force of the biasing spring 6. This causes the connection port 43 to communicate with the supply port 42, as shown in Figure 4. In the state shown in Figure 4, the first notch 531 is not engaged with the inner wall of the spool hole 41, but is separated from the inner wall of the spool hole 41. On the other hand, the connection port 43 is isolated from the tank port 44 by the second land portion 54.

[0039] When the connection port 43 communicates with the supply port 42, the hydraulic fluid supplied from the hydraulic pump through the pump oil passage 91 passes through the gap between the first land portion 53 of the spool 5 and the inner wall of the spool hole 41, as shown by arrows A21 and A22 in Figure 4. Subsequently, as shown by arrow A23 in Figure 4, the hydraulic fluid passes through the gap between the first rod portion 571 of the spool 5 and the inner wall of the spool hole 41. Subsequently, as shown by arrows A24 and A25 in Figure 4, the hydraulic fluid passes through the connection port 43 and flows through the actuator oil passage 92 to be supplied to the actuator. This applies pressure generated by the hydraulic fluid to the actuator.

[0040] Furthermore, as mentioned above with respect to Figure 3, the diameter D2 of the second land portion 54 is larger than the diameter D1 of the first land portion. Therefore, in the axial direction of the spool 5, the area of ​​the second land portion 54 that receives pressure from the hydraulic fluid is larger than the area of ​​the first land portion 53 that receives pressure from the hydraulic fluid. For the sake of explanation, the area of ​​each land portion that receives pressure from the hydraulic fluid in the axial direction of the spool 5 will be referred to as the "pressure-receiving area".

[0041] The spool 5 receives a thrust proportional to the difference between the pressure-receiving area of ​​the second land portion 54 and the pressure-receiving area of ​​the first land portion 53. Specifically, the magnitude of the thrust that the spool 5 receives from the hydraulic fluid is "(difference between the pressure-receiving area of ​​the second land portion 54 and the pressure-receiving area of ​​the first land portion 53) × (pressure generated by the hydraulic fluid (i.e., the pressure that the actuator receives from the hydraulic fluid))". Since the diameter D2 of the second land portion 54 is larger than the diameter D1 of the first land portion, the direction of the thrust that the spool 5 receives from the hydraulic fluid is in the direction of the initial position of the spool 5 (to the left in Figure 4).

[0042] As the amount of hydraulic fluid supplied to the actuator increases, the pressure generated by the hydraulic fluid (i.e., the pressure the actuator receives from the hydraulic fluid) increases. When the resultant force of the thrust that the spool 5 receives from the hydraulic fluid and the biasing force of the biasing spring 6 becomes greater than the thrust that the spool 5 receives from the solenoid 3, the spool 5 moves in the direction of its initial position (to the left in Figure 4).

[0043] As the spool 5 moves in the direction of its initial position, the first notch 531 engages with the inner wall of the spool hole 41, as shown in Figure 5. In other words, the connection port 43 communicates with the supply port 42 through the first notch 531. On the other hand, the connection port 43 remains isolated from the tank port 44 by the second land portion 54.

[0044] When the connection port 43 is in communication with the supply port 42 through the first notch 531, the hydraulic fluid supplied from the hydraulic pump through the pump oil passage 91 flows through the first notch 531, as shown by arrows A31 and A32 in Figure 5. Subsequently, as shown by arrow A33 in Figure 5, the hydraulic fluid that has flowed through the first notch 531 passes through the gap between the first rod portion 571 of the spool 5 and the inner wall of the spool hole 41. Subsequently, as shown by arrows A34 and A35 in Figure 5, the hydraulic fluid passes through the connection port 43 and flows through the actuator oil passage 92 to be supplied to the actuator.

[0045] In the state shown in Figure 5, the hydraulic fluid flows through the first notch 531 and is supplied to the actuator, so the amount of hydraulic fluid supplied to the actuator per unit time is less than in the state shown in Figure 4. Therefore, the pressure on the actuator from the hydraulic fluid increases more gradually compared to the state shown in Figure 4. Consequently, the thrust on the spool 5 from the hydraulic fluid increases more gradually compared to the state shown in Figure 4. As a result, the spool 5 moves at a lower speed than when the first notch 531 is not engaged with the inner wall of the spool hole 41 (for example, the state shown in Figure 4).

[0046] As shown in Figure 6, when the first notch 531 is closed by the inner wall of the spool hole 41, the connection port 43 is isolated from the supply port 42 by the first land portion 53. This stops the flow of hydraulic fluid supplied to the actuator. In the state shown in Figure 6, the second notch 541 is closed by the inner wall of the spool hole 41, similar to the first notch 531. In other words, the connection port 43 remains isolated from the tank port 44 by the second land portion 54.

[0047] If, in the state shown in Figure 6, the resultant force of the thrust that the spool 5 receives from the hydraulic fluid and the biasing force of the biasing spring 6 is greater than the thrust that the spool 5 receives from the solenoid 3, then the spool 5 will move further in the direction of its initial position (to the left in Figure 6). When this happens, the second notch 541 will open, as shown in Figure 7.

[0048] In the hydraulic valve 2 according to this embodiment, as shown in Figures 5 to 7, the timing at which the first notch 531 is completely closed by the inner wall of the spool hole 41 is the same as the timing at which the second notch 541 begins to open. Also, the timing at which the first notch 531 begins to open is the same as the timing at which the second notch 541 is completely closed by the inner wall of the spool hole 41.

[0049] As shown in Figure 7, when the second notch 541 is opened, the connection port 43 communicates with the tank port 44 through the second notch 541. On the other hand, the connection port 43 remains isolated from the supply port 42 by the first land portion 53.

[0050] When the connection port 43 is in communication with the tank port 44 through the second notch 541, as shown by arrows A51 and A52 in Figure 7, the hydraulic fluid is discharged from the actuator, flows through the actuator oil passage 92, and passes through the connection port 43. Subsequently, as shown by arrow A53 in Figure 7, the hydraulic fluid that has passed through the connection port 43 passes through the gap between the third land portion 55 of the spool 5 and the inner wall of the spool hole 41. Subsequently, as shown by arrow A54 in Figure 7, the hydraulic fluid passes through the gap between the second rod portion 572 of the spool 5 and the inner wall of the spool hole 41. Subsequently, as shown by arrow A55 in Figure 7, the hydraulic fluid flows through the second notch 541. Subsequently, as shown by arrows A56 and A57 in Figure 7, the hydraulic fluid passes through the tank port 44, flows through the tank oil passage 93, and is led to the tank.

[0051] In the state shown in Figure 7, the hydraulic fluid flows through the second notch 541 and is discharged into the tank. Therefore, the amount of hydraulic fluid discharged from the actuator per unit time is less than in the state where the second notch 541 is not applied to the inner wall of the spool hole 41 (for example, the state shown in Figure 8). Consequently, the pressure exerted on the actuator by the hydraulic fluid decreases more gently compared to the state shown in Figure 8. As a result, the thrust exerted on the spool 5 by the hydraulic fluid decreases more gently compared to the state shown in Figure 8. Consequently, the spool 5 moves at a lower speed than in the state where the second notch 541 is not applied to the inner wall of the spool hole 41 (for example, the state shown in Figure 8).

[0052] When the hydraulic fluid is discharged from the actuator, the pressure generated by the hydraulic fluid (i.e., the pressure the actuator receives from the hydraulic fluid) decreases. Then, if, in the state shown in Figure 7, the resultant force of the thrust that the spool 5 receives from the hydraulic fluid and the biasing force of the biasing spring 6 becomes smaller than the thrust that the spool 5 receives from the solenoid 3, the spool 5 will move in the opposite direction to its initial position (to the right in Figure 7).

[0053] When the spool 5 moves in the opposite direction to its initial position, the second notch 541 closes against the inner wall of the spool hole 41, as shown in Figure 6. This isolates the connection port 43 from the tank port 44 by the second land portion 54. As a result, the flow of hydraulic fluid discharged from the actuator stops. The state shown in Figure 6 is as described above.

[0054] In this way, the resultant force of the thrust that the spool 5 receives from the hydraulic fluid and the biasing force of the biasing spring 6 balances the thrust that the spool 5 receives from the solenoid 3, thereby generating the pressure that the hydraulic valve 2 applies to the actuator with the hydraulic fluid. At this time, as mentioned above, the thrust that the spool 5 receives from the hydraulic fluid when it is in operation rises and falls gently. As a result, the hydraulic valve 2 according to this embodiment can ensure the stability of the operation of the spool 5.

[0055] Next, we will explain the action of releasing the pressure that an actuator receives from the hydraulic fluid, such as when switching clutches. When the actuator pressure is released from a state where the resultant force of the thrust that the spool 5 receives from the hydraulic fluid and the biasing force of the biasing spring 6 balances the thrust that the spool 5 receives from the solenoid 3 (for example, the state shown in Figure 6), the control unit (not shown) reduces the current value flowing through the conductor of the coil 32.

[0056] As a result, the thrust applied to the spool 5 by the solenoid 3 decreases, and the spool 5 moves in the direction of its initial position (to the left in Figure 6). In other words, the thrust applied to the spool 5 by the solenoid 3 becomes smaller than the resultant force of the thrust received by the spool 5 from the hydraulic fluid and the biasing force of the biasing spring 6. As a result, the connection port 43 communicates with the tank port 44, as shown in Figure 8. In the state shown in Figure 8, the second notch 541 is not engaged with the inner wall of the spool hole 41, but is away from the inner wall of the spool hole 41. On the other hand, the connection port 43 remains isolated from the supply port 42 by the second land portion 54.

[0057] When the connection port 43 communicates with the tank port 44, as shown by arrows A61 and A62 in Figure 8, the hydraulic fluid is discharged from the actuator, flows through the actuator oil passage 92, and passes through the connection port 43. Subsequently, as shown by arrow A63 in Figure 8, the hydraulic fluid that has passed through the connection port 43 passes through the gap between the third land portion 55 of the spool 5 and the inner wall of the spool hole 41. Subsequently, as shown by arrow A64 in Figure 8, the hydraulic fluid passes through the gap between the second rod portion 572 of the spool 5 and the inner wall of the spool hole 41. Subsequently, as shown by arrow A65 in Figure 8, the hydraulic fluid passes through the gap between the second land portion 54 of the spool 5 and the inner wall of the spool hole 41. Subsequently, as shown by arrows A66 and A67 in Figure 8, the hydraulic fluid passes through the tank port 44, flows through the tank oil passage 93, and is led to the tank.

[0058] Furthermore, as shown in Figure 8, when the second notch 541 separates from the inner wall of the spool hole 41, that is, when the second land portion 54 separates from the inner wall of the spool hole 41, the second oil passage 52 of the spool 5 opens. In other words, the outer opening of the second oil passage 52, which was previously closed by the inner wall surface of the spool hole 41, opens.

[0059] In the hydraulic valve 2 according to this embodiment, as shown in Figures 7 to 8, the timing at which the second land portion 54 separates from the inner wall of the spool hole 41 is the same as the timing at which the second oil passage 52 of the spool 5 begins to open. In other words, when the connection port 43 is not in communication with the tank port 44, the outer opening of the second oil passage 52 is closed by the sleeve 4 (specifically, the inner wall of the spool hole 41). For example, as shown in Figures 4 to 7, when the hydraulic valve 2 is controlling the pressure applied to the actuator by the hydraulic fluid, the outer opening of the second oil passage 52 is closed by the inner wall of the spool hole 41.

[0060] When the outer opening of the second oil passage 52 opens, as shown by arrows A71 and A72 in Figure 8, the hydraulic fluid that has passed through the connection port 43 passes through the gap between the third land portion 55 of the spool 5 and the inner wall of the spool hole 41, and also passes through the second oil passage 52, and is guided to the first oil passage 51 formed inside the spool 5. The hydraulic fluid guided to the first oil passage 51 flows through the first oil passage 51 and imparts additional thrusts F1 and F2 to the spool 5 that move the spool 5 in the direction of its initial position (to the left in Figure 8).

[0061] To explain in more detail, as shown by arrow A73 in Figure 8, the hydraulic fluid guided into the first oil passage 51 flows toward one end 58 of the spool 5, and acts on the inner wall surface of the first oil passage 51 at one end 58 of the spool 5, thereby imparting an additional thrust F1 to the spool 5 in the direction of the initial position (leftward in Figure 8). As shown by arrows A75 and A76 in Figure 8, the hydraulic fluid that has flowed toward one end 58 of the spool 5 passes through the third oil passage 56 of the spool 5 and flows through the gap between the spool 5 and the inner wall of the spool hole 41, and merges with the hydraulic fluid that has passed through the gap between the second land portion 54 of the spool 5 and the inner wall of the spool hole 41 (see arrow A65). As shown by arrows A66 and A67 in Figure 8, the merged hydraulic fluid passes through the tank port 44 and flows through the tank oil passage 93 to the tank.

[0062] Furthermore, as shown by arrow A74 in Figure 8, the hydraulic fluid guided into the first oil passage 51 flows toward the other end 59 of the spool 5, passes through the opening at the other end 59 of the spool 5, and flows out into the spool hole 41. The hydraulic fluid that flows out of the spool 5 into the spool hole 41 acts on the outer end surface of the spool 5 at the other end 59 of the spool 5, thereby imparting an additional thrust F2 to the spool 5 in the direction of the initial position (leftward in Figure 8).

[0063] In this way, the hydraulic fluid that has passed through the second oil passage 52 and been guided into the first oil passage 51 acts on the entire cross-section of the spool 5 that intersects (specifically, is perpendicular to) the axis of the spool 5, and imparts additional thrusts F1 and F2 to the spool 5 in the direction of the initial position (to the left in Figure 8).

[0064] As described above, according to the hydraulic valve 2 of this embodiment, when the connection port 43 communicates with the tank port 44, the hydraulic fluid discharged from the actuator and passing through the connection port 43 flows through the second oil passage 52 and into the first oil passage 51. The hydraulic fluid that flows into the first oil passage 51 then imparts additional thrusts F1 and F2 to the spool 5, moving it in the direction of its initial position. Specifically, the hydraulic fluid guided into the first oil passage 51 flows toward one end 58 of the spool 5 and acts on the inner wall surface of the first oil passage 51 at one end 58 of the spool 5, thereby imparting additional thrust F1 to the spool 5. Furthermore, the hydraulic fluid guided into the first oil passage 51 flows toward the other end 59 of the spool 5, passes through the opening and flows out into the spool hole 41, and acts on the outer end surface of the spool 5 at the other end 59, thereby imparting additional thrust F2 to the spool 5.

[0065] As a result, the thrust of the solenoid 3 decreases, and when the connection port 43 communicates with the tank port 44, the spool 5 receives a biasing force from the biasing spring 6 and additional thrusts F1 and F2 from the hydraulic fluid flowing through the first oil passage 51, causing it to move in the direction of its initial position. Therefore, the hydraulic valve 2 according to this embodiment can improve responsiveness by increasing the speed at which the spool 5 moves in the direction of its initial position, while ensuring stability by maintaining the gap (i.e., opening) between the sleeve 4 and the spool 5, which affects the stability of the spool 5's operation.

[0066] Furthermore, the hydraulic valve 2 according to this embodiment applies additional thrusts F1 and F2 to the spool 5 by utilizing the pressure of the actuator, which is the target for improving responsiveness, i.e., the actuator that accelerates release. Therefore, no special mechanism is required to generate the additional thrusts F1 and F2 that move the spool 5 in the direction of its initial position. As a result, the hydraulic valve 2 according to this embodiment can improve responsiveness while simplifying its structure.

[0067] Furthermore, without changing the shape of the mating component (e.g., valve block 9) to which the hydraulic valve 2 is mounted, the hydraulic valve 2 according to this embodiment can improve responsiveness while ensuring stability. Therefore, it is possible to prevent the mating component (e.g., valve block 9) to which the hydraulic valve 2 is mounted from becoming larger.

[0068] Furthermore, when the connection port 43 is not in communication with the tank port 44, the outer opening of the second oil passage 52 is closed by the sleeve 4 (specifically, the inner wall of the spool hole 41). Therefore, when the connection port 43 is not in communication with the tank port 44, it is possible to prevent the hydraulic fluid from passing through the second oil passage 52 to the first oil passage 51. As a result, it is possible to prevent the first oil passage 51 and the second oil passage 52 from affecting the control of the actuator's operation.

[0069] Furthermore, as the hydraulic fluid flows through at least one of the first notch 531 and the second notch 541, the thrust that the spool 5 receives from the hydraulic fluid during operation rises and falls gently. As a result, the hydraulic valve 2 according to this embodiment can further ensure the stability of the spool 5's operation.

[0070] Embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the claims. The configurations of the above embodiments can be partially omitted or combined in any way different from those described above. [Explanation of Symbols]

[0071] 2: Hydraulic valve, 3: Solenoid, 4: Sleeve, 5: Spool, 6: Biasing spring, 9: Valve block, 31: Case, 32: Coil, 33: Plunger, 34: Base, 35: Push pin, 41: Spool hole, 42: Supply port, 43: Connection port, 44: Tank port, 45: End, 48: Groove, 49: O-ring, 51: First oil passage, 52: Second oil passage, 53: First land section, 54: Second land section, 55: Third land section, 56: Third oil passage, 58: End, 59: End, 91: Pump oil passage, 92: Actuator oil passage, 93: Tank oil passage, 531: First notch, 532: First outer surface, 533: First wall surface, 541: Second notch, 542: Second outer surface, 543: Second wall surface, 571: First rod section, 572: Second rod section, 581: Flange section

Claims

1. A solenoid converts electrical energy into mechanical energy for linear motion, A sleeve fixed to the solenoid and having a spool hole extending in the direction of the linear motion, A spool is disposed inside the spool hole and moves along the axial direction of the spool hole in response to the thrust applied by the solenoid, A biasing spring is positioned between the sleeve and the spool and biases the spool in the direction of its initial position. Equipped with, The aforementioned sleeve is A supply port through which the hydraulic fluid supplied from the hydraulic pump passes, A connection port through which the hydraulic fluid supplied to the actuator and the hydraulic fluid discharged from the actuator pass, A tank port through which the hydraulic fluid, which is led to the tank, It has, The aforementioned spool is A first oil passage is formed inside the spool, extending along the axial direction, A second oil passage connects the first oil passage and the spool hole, It has, A hydraulic valve characterized in that, when the connection port communicates with the tank port, the hydraulic fluid discharged from the actuator and passing through the connection port flows through the second oil passage to the first oil passage, providing the spool with an additional thrust that moves the spool in the direction of the initial position.

2. The first oil passage is closed at one end of the spool in the direction of the initial position, The hydraulic valve according to claim 1, characterized in that the hydraulic fluid flowing through the first oil passage acts on the inner wall surface of the first oil passage at one end, thereby providing the additional thrust to the spool.

3. The first oil passage opens at the other end of the spool in the direction opposite to the direction of the initial position, The hydraulic valve according to claim 1, characterized in that the hydraulic fluid flowing through the first oil passage flows out through the opening into the spool hole and acts on the outer end surface of the spool at the other end to provide the additional thrust to the spool.

4. The hydraulic valve according to claim 1, characterized in that when the connection port is not in communication with the tank port, the outer opening of the second oil passage is closed by the sleeve.

5. The aforementioned spool is A first land portion is fitted into the spool hole so as to be movable along the axial direction, A second land portion is provided at a distance from the first land portion in the axial direction and is fitted into the spool hole so as to be movable along the axial direction, A rod portion provided between the first land portion and the second land portion, having a diameter smaller than the diameters of the first land portion and the second land portion, It has, The first land section is, The first wall surface rising radially outward from the rod portion, A first notch formed at the boundary between the first wall surface and the outer peripheral surface of the first land portion, It has, The second land portion is, A second wall surface rising radially outward from the rod portion, A second notch formed at the boundary between the second wall surface and the outer peripheral surface of the second land portion, The hydraulic valve according to claim 1, characterized by having the following features.

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