Oil control valve

Abstract

This oil control valve is provided with: a housing (21) having a discharge port (21b) for discharging hydraulic oil to the outside; a spool (22) that is supported on the inner peripheral surface of the housing (21) so as to be movable in the axial direction and has, on the outer peripheral surface thereof, a discharge opening (22b) for discharging, to the discharge port (21b), the hydraulic oil supplied to the inside; and an annular groove (21d) formed on the inner peripheral surface of the housing (21) so as to face the discharge opening (22b).

Description

Oil Control Valve

[0001] The present disclosure relates to an oil control valve.

[0002] Patent Document 1 discloses an oil control valve. The oil control valve disclosed in Patent Document 1 movably supports a spool within a sleeve, which is a housing, and is capable of adjusting the flow rate of hydraulic oil according to the movement position of the spool.

[0003] Japanese Patent Application Laid-Open No. 2004-176895

[0004] The oil control valve disclosed in Patent Document 1 aims to reduce the pressure of hydraulic oil acting on the spool. Generally, the closer the angle of the hydraulic oil flowing out of the spool's discharge opening is to a right angle relative to the axial direction of the spool, the lower the pressure of the hydraulic oil acting on the spool. Therefore, the oil control valve disclosed in Patent Document 1 takes advantage of this characteristic by providing a port on the outside of the housing that extends perpendicular to the axial direction of the spool. However, adopting such a configuration requires providing a separate member for the port on the outside of the sleeve, which results in a problem of an increased outer diameter of the oil control valve.

[0005] The present disclosure has been made to solve the above-mentioned problems, and aims to provide a device that can reduce the pressure of hydraulic oil acting on a spool without increasing the outer diameter.

[0006] The device disclosed herein comprises a housing having a discharge port for discharging hydraulic oil to the outside, a spool supported on the inner surface of the housing so as to be movable axially and having a discharge opening on its outer surface for discharging hydraulic oil supplied to the interior to the discharge port, and an annular groove formed on the inner surface of the housing so as to face the discharge opening.

[0007] According to the present disclosure, the pressure of the hydraulic oil acting on the spool can be reduced without increasing the outer diameter of the oil control valve.

[0008] FIG. 5A is a longitudinal cross-sectional view of the oil control valve according to Embodiment 1. FIG. 5B is a longitudinal cross-sectional view of the oil control valve according to Embodiment 1 (not energized) when the spool has moved to the initial position. FIG. 5C is a longitudinal cross-sectional view of the oil control valve according to Embodiment 1 (energized) when the spool has moved to the full stroke position. FIG. 5D is a longitudinal cross-sectional view of the oil control valve according to Embodiment 1, showing a state in which a communicating portion is throttled. FIG. 5E is a diagram showing the flow velocity distribution of hydraulic oil in the oil control valve according to Embodiment 1. FIG. 5A is an overall view. FIG. 5B is an enlarged view of a main portion of FIG. 5A. FIG. 6A is a diagram showing the pressure distribution of hydraulic oil in the oil control valve according to Embodiment 1. FIG. 6B is an enlarged view of a main portion of FIG. 6A. FIG. 5D is a longitudinal cross-sectional view of a conventional oil control valve. FIG. 6E is a diagram showing the flow velocity distribution of hydraulic oil in the conventional oil control valve. FIG. 8A is an overall view. FIG. 8B is an enlarged view of a main portion of FIG. 8A. FIG. 9A is a diagram showing the pressure distribution of hydraulic oil in the conventional oil control valve. FIG. 9B is an overall view. FIG. 9B is an enlarged view of a main portion of FIG. 9A. 10A and 10B show modified examples of the supply opening;

[0009] In order to explain the present disclosure in more detail, embodiments of the present disclosure will be described below with reference to the accompanying drawings.

[0010] First Embodiment An oil control valve according to a first embodiment will be described with reference to FIGS.

[0011] First, the configuration of an oil control valve according to a first embodiment will be described with reference to Fig. 1. Fig. 1 is a longitudinal cross-sectional view of the oil control valve according to the first embodiment. Note that the arrows in Fig. 1 indicate the flow direction of hydraulic oil. Also, the gray portions in Fig. 1 indicate hydraulic oil.

[0012] As shown in FIG. 1 , the oil control valve according to the first embodiment is attached to a valve mounting member 100. The valve mounting member 100 has an oil passage 101. This oil passage 101 is for supplying hydraulic oil to a target device. The oil passage 101 is formed so as to bend at a right angle. The oil control valve according to the first embodiment is provided in the valve mounting member 100 at a position corresponding to the bent portion of the oil passage 101. The oil control valve according to the first embodiment controls the flow rate of hydraulic oil supplied to the target device by adjusting the valve opening.

[0013] The oil control valve according to the first embodiment includes a solenoid unit 10 and a valve unit 20. The solenoid unit 10 and the valve unit 20 are attached to each other in the axial direction of the oil control valve. The solenoid unit 10 is exposed from the top surface of a valve mounting member 100. The valve unit 20 is fitted into the valve mounting member 100 and communicates with an oil passage 101.

[0014] The solenoid unit 10 includes a case 11, a terminal 12, a bracket 13, a coil 14, a core 15, a plunger 16, a shaft 17, and a boss 18. The core 15, the plunger 16, the shaft 17, and the boss 18 are arranged coaxially.

[0015] The case 11 forms the outer shell of the solenoid unit 10. The case 11 has a substantially cylindrical shape. A bracket 13, a coil 14, a core 15, a plunger 16, a shaft 17, and a boss 18 are arranged radially inside the case 11.

[0016] The coil 14 is formed by winding a copper wire around the outer peripheral surface of a cylindrical bobbin. One end of the coil 14 is connected to the terminal 12, and the other end of the coil 14 is connected to a terminal of the bobbin. The terminal 12 is disposed radially outside the case 11.

[0017] The bracket 13 is a member for fixing the oil control according to the first embodiment to the valve mounting member 100. The bracket 13 is provided at the bottom inside the case 11. The valve unit 20 is provided below the bracket 13.

[0018] The bracket 13 has a circular annular portion 13a and a mounting portion 13b. The circular annular portion 13a has a circular ring shape and is provided on the radially inner side of the case 11. Therefore, the inside of the case 11 communicates with the inside of a valve portion 20 (described later) via the inside of a boss 18 (described later).

[0019] The mounting portion 13b is formed to extend radially outward from the circular annular portion 13a and is disposed radially outward of the case 11. The mounting portion 13b also has a bolt-through hole at its tip. The oil control according to embodiment 1 is fixed to the valve mounting member 100 by fastening a bolt 110 through the bolt-through hole in the mounting portion 13b of the bracket 13 and into a threaded hole in the valve mounting member 100.

[0020] The core 15 is cylindrical and has a bottom. The core 15 has a bottom at its upper end and an opening at its lower end. The core 15 is disposed on the upper end side of the coil 14 and radially inward of the coil 14.

[0021] The plunger 16 has a cylindrical shape and is supported on the inner peripheral surface of the core 15 so as to be movable in the axial direction of the core 15, i.e., the axial direction of the plunger 16.

[0022] The shaft 17 is fixed to the lower part of the plunger 16. Therefore, the shaft 17 moves together with the plunger 16.

[0023] The boss 18 has a cylindrical shape. The boss 18 is disposed on the lower end side of the coil 14 and is disposed radially inward of the coil 14. A predetermined gap is formed in the axial direction between the upper surface of the boss 18 and the lower surface of the plunger 16. In this way, by providing a predetermined gap in the axial direction between the boss 18 and the plunger 16, the boss 18 does not come into contact with the plunger 16, which moves in the axial direction.

[0024] The lower end of the boss 18 is fitted into a circular hole in the circular annular portion 13a of the bracket 13. Therefore, the central hole of the boss 18 communicates with the interior of a valve portion 20 (described later). The shaft 17 fixed to the plunger 16 passes through the central hole of the boss 18 and enters the interior of the valve portion 20. In other words, the tip of the shaft 17 is located inside the valve portion 20.

[0025] The valve portion 20 includes a housing 21 , a spool 22 , and a compression spring 23 .

[0026] The housing 21 has a cylindrical shape. The upper end of the housing 21 is fixed to the bracket 13. The lower end of the housing 21 communicates with the oil passage 101.

[0027] The housing 21 also has a supply port 21a, discharge ports 21b and 21c, and an annular groove 21d.

[0028] The supply port 21a is for supplying hydraulic oil from the oil passage 101 into the housing 21 and the spool 22. The supply port 21a is provided at the lower end of the housing 21. The supply port 21a is in communication with the oil passage 101 and the lower end of the spool 22, respectively.

[0029] The discharge ports 21b and 21c are used to discharge the hydraulic oil supplied into the spool 22 to the oil passage 101. The discharge ports 21b and 21c are through holes that radially penetrate the outer peripheral surface of the housing 21. The discharge ports 21b and 21c are provided at two different positions in the axial direction of the housing 21. The discharge port 21b is located closer to the upper end of the housing 21 than the discharge port 21c.

[0030] The annular groove 21d is formed on the inner peripheral surface of the housing 21 along the circumferential direction of the housing 21. The annular groove 21d is disposed between the discharge ports 21b and 21c in the axial direction of the housing 21, and is formed so as not to overlap with the discharge ports 21b and 21c. The annular groove 21d is also disposed in a position that always faces a discharge opening 22b of the spool 22, which will be described later.

[0031] The spool 22 is supported on the inner peripheral surface of the housing 21 so as to be movable in the axial direction of the housing 21, i.e., the axial direction of the spool 22. The spool 22 has a cylindrical shape with a bottom. The spool 22 is disposed so that the bottom is the upper end and the opening is the lower end. The tip of the shaft 17 can abut against the upper surface of the spool 22.

[0032] The spool 22 has a supply opening 22a and a discharge opening 22b.

[0033] The supply opening 22a is for supplying hydraulic oil supplied from the oil passage 101 via the supply port 21a into the spool 22. The supply opening 22a forms a lower end opening of the spool 22. The diameter of the inner circumferential surface of the supply opening 22a is gradually reduced from the lower end side to the upper end side of the spool 22. In other words, the diameter of the inner circumferential surface of the supply opening 22a is gradually reduced toward the discharge opening 22b described below. For example, the inner circumferential surface of the supply opening 22a is a tapered surface whose inner diameter gradually reduces toward the discharge opening 22b of the spool 22.

[0034] The discharge opening 22b is for discharging the hydraulic oil supplied into the spool 22 by the supply opening 22a into the oil passage 101 via the discharge port 21b. The discharge opening 22b is a through-hole that radially penetrates the outer circumferential surface of the spool 22. The discharge opening 22b is positioned so as to face at least a portion of the annular groove 21d even when the spool 22 moves.

[0035] The compression spring 23 is interposed in a compressed state between the inner surface of the lower end of the housing 21 and the inner surface of the upper end of the spool 22. Therefore, the compression spring 23 constantly biases the spool 22 toward the solenoid unit 10.

[0036] Next, the operation of the oil control valve according to the first embodiment will be described with reference to FIGS. 2 and 3. FIG.

[0037] 2 and 3 are longitudinal cross-sectional views of the oil control valve (without current) according to the first embodiment when the spool 22 has moved to the initial position and the full stroke position, respectively.

[0038] The axial movement position of the spool 22 is determined primarily by the balance of forces among the magnetic attractive force of the plunger 16, the biasing force of the compression spring 23, and the pressure of hydraulic oil acting on each movable part (e.g., plunger 16, shaft 17, and spool 22). As shown in FIG. 1 , the interior and surrounding areas of the movable parts are constantly filled with hydraulic oil, indicated in gray. The oil control valve according to the first embodiment adjusts the magnitude of the current applied to the coil 14 to change the magnetic attractive force of the plunger 16, thereby moving the spool 22 to a predetermined position. Therefore, the oil control valve according to the first embodiment is capable of controlling the flow rate of hydraulic oil.

[0039] Specifically, as shown in FIG. 2 , when no current is applied to the coil 14, the coil 14 does not generate magnetic flux. Therefore, the plunger 16 does not generate a magnetic attraction force toward the boss 18. In contrast, the compression spring 23 urges the spool 22 upward. As a result, the spool 22 moves upward and ultimately to its initial position, which is the final position in the valve-opening direction. During this movement, the spool 22 also pushes up the plunger 16 and the shaft 17.

[0040] In this way, when spool 22 moves upward, a portion of discharge port 21b in housing 21 faces a portion of discharge opening 22b in spool 22. Furthermore, discharge port 21c in housing 21 is opened by the upward movement of spool 22. Therefore, the oil control valve according to the first embodiment is in an open state.

[0041] Therefore, the hydraulic oil supplied into the spool 22 is discharged from the discharge opening 22b via the discharge port 21b into the oil passage 101. Furthermore, after the hydraulic oil is supplied from the supply port 21a into the housing 21, the hydraulic oil that does not flow from the supply opening 22a into the spool 22 is discharged directly into the oil passage 101 via the discharge port 21c.

[0042] 3, when the oil control valve is energized, that is, when a predetermined amount of current is applied to the coil 14, the coil 14 generates a magnetic flux. As a result, the plunger 16 generates a magnetic attractive force that attracts it to the boss 18. As a result, the plunger 16 moves downward together with the shaft 17. At this time, the plunger 16 moves against the biasing force of the compression spring 23, and the spool 22 ultimately moves to the full stroke position, which is the final position in the valve closing direction.

[0043] As the spool 22 moves downward in this manner, the discharge opening 22b of the spool 22 moves downward from the discharge port 21b of the housing 21 and is blocked by the inner circumferential surface of the housing 21. In addition, the discharge port 21c of the housing 21 is blocked by the downward movement of the spool 22. Therefore, the oil control valve according to the first embodiment is in a closed state.

[0044] Therefore, hydraulic oil supplied into the spool 22 is not discharged from the discharge opening 22b through the discharge port 21b. Furthermore, hydraulic oil that is supplied from the supply port 21a into the housing 21 and does not flow from the supply opening 22c into the spool 22 is not discharged through the discharge port 21c.

[0045] Next, the effects achieved by the oil control valve according to the first embodiment will be described with reference to FIGS. 4 to 9, in comparison with a conventional oil control valve.

[0046] Fig. 4 is a longitudinal cross-sectional view showing a state in which the communicating portion 31 of the oil control valve according to the first embodiment is throttled. Fig. 5 is a diagram showing the flow velocity distribution of hydraulic oil in the oil control valve according to the first embodiment. Fig. 6 is a diagram showing the pressure distribution of hydraulic oil in the oil control valve according to the first embodiment. Fig. 7 is a longitudinal cross-sectional view of a conventional oil control valve. Fig. 8 is a diagram showing the flow velocity distribution of hydraulic oil in the conventional oil control valve. Fig. 9 is a diagram showing the pressure distribution of hydraulic oil in the conventional oil control valve.

[0047] 4, 5, and 6 correspond to states of the oil control valve according to the first embodiment. Also, FIGS. 7, 8, and 9 correspond to states of a conventional control valve. Also, FIG. 7 is a vertical cross-sectional view showing a state in which the communication portion 31 of the conventional oil control valve is throttled. FIGS. 4 and 7 illustrate the case in which the spool 22 moves to an intermediate position between the initial position and the full stroke position, i.e., the case in which the valve gradually transitions from an open state to a closed state.

[0048] The conventional oil control valve shown in Figure 7 has a solenoid unit 10 and a valve unit 20A. The conventional valve unit 20A has a configuration in which the annular groove 21d and the supply opening 22a are removed from the configuration of the valve unit 20 according to the first embodiment. In other words, the conventional oil control valve does not have the annular groove 21d or the supply opening 22a. The conventional valve unit 20A has a supply opening 22d instead of the supply opening 22a. The diameter of the inner peripheral surface of this supply opening 22d is uniform in the axial direction.

[0049] In a conventional oil control valve, when a large flow rate of hydraulic oil flows, the flow velocity increases near the discharge opening 22b, resulting in a large pressure drop of the hydraulic oil, as shown in Figures 7 to 9. Here, the vicinity of the discharge opening 22b refers to, for example, a localized portion where a portion of the discharge opening 22b communicates with a portion of the discharge port 21b (hereinafter referred to as a communication portion 31). A vortex 42 of the hydraulic oil is generated in the region located upstream of the communication portion 31 and between the discharge opening 22b and the inner circumferential surface of the housing 21. However, because this vortex 42 is small, the pressure drop caused by the vortex 42 is small.

[0050] As a result, the pressure of the filled hydraulic oil that pushes the spool 22 toward the plunger 16 decreases. In contrast, the pressure of the filled hydraulic oil that pushes the spool 22 toward the compression spring 23 increases. At this time, if the pressure of the filled hydraulic oil that pushes the spool 22 toward the compression spring 23 exceeds the biasing force of the compression spring 23, it becomes difficult to control the movement of the spool 22.

[0051] To solve this problem, it is conceivable to make the magnetic attractive force of the plunger 16 sufficiently greater than the pressure of the filled hydraulic oil that pushes the spool 22 toward the compression spring 23. However, in order to increase the magnetic attractive force of the plunger 16, it is necessary to increase the number of turns of the coil 14 or increase the current applied to the coil 14. This makes it difficult to reduce the size or power consumption of the oil control valve.

[0052] In contrast, as shown in Figures 4 and 5, the oil control valve according to the first embodiment has an annular groove 21d provided at a position corresponding to where a vortex 42 of the hydraulic oil is generated when the communication portion 31 is formed. This facilitates the generation of the vortex 42, i.e., makes the vortex 42 larger. The vortex 41 shown in Figure 5 facilitates the generation of the vortex 42 shown in Figure 8. Therefore, the pressure of the large vortex 41 is lower than the pressure of the small vortex 42. As a result, the pressure in the communication portion 31 in the oil control valve according to the first embodiment is lower than the pressure in the communication portion 31 in a conventional oil control valve. This reduces the pressure of the hydraulic oil acting on the spool 22.

[0053] Here, the annular groove 21d is positioned at a position that makes the groove width largest when a vortex 42 (vortex 41) of the hydraulic oil is generated during the formation of the communication portion 31. Therefore, the annular groove 21d can easily promote the generation of the vortex 41.

[0054] Therefore, when the pressure of the filled hydraulic oil that pushes the spool 22 toward the plunger 16 decreases, the pressure of the filled hydraulic oil that pushes the spool 22 toward the compression spring 23 also decreases, thereby eliminating the imbalance in pressure in the filled hydraulic oil that acts in the operating direction of the movable parts.

[0055] Furthermore, the spool 22 has the supply opening 22a whose inner diameter decreases toward the discharge opening 22b, allowing the hydraulic oil to flow efficiently toward the annular groove 21d. This allows the spool 22 to promote the generation of the vortex 41, thereby increasing the pressure drop caused by the vortex 41.

[0056] That is, in the oil control valve according to the first embodiment, the formation of the communication portion 31 increases the flow rate of the hydraulic oil in the communication portion 31, and the pressure pushing the spool 22 upward (toward the plunger 16) is greatly reduced, but the generation of the vortex 41 is promoted by the annular groove 21d, which also greatly reduces the pressure pushing the spool 22 downward (toward the compression spring 23). As a result, the oil control valve according to the first embodiment can eliminate the imbalance in the balance of forces in the vertical or axial direction on the spool 22.

[0057] Therefore, the oil control valve according to the first embodiment can eliminate the imbalance in pressure acting in the operating direction of the movable parts in the filled hydraulic oil without increasing the number of turns of the coil 14 or the current applied to the coil 14. Therefore, the oil control valve according to the first embodiment can be made smaller and consume less power.

[0058] The groove shape of the annular groove 21d in the housing 21 may be adjusted as appropriate. Fig. 10 is a diagram showing a first modified example of the annular groove 21d. As shown in Fig. 10, the annular groove 21e is a V-shaped groove, and its groove shape is V-shaped. Fig. 11 is a diagram showing a second modified example of the annular groove 21d. As shown in Fig. 11, the annular groove 21f is a U-shaped groove, and its groove shape is U-shaped.

[0059] The shape of the inner peripheral surface of the supply opening 22a of the spool 22 may be adjusted as appropriate. Fig. 12 shows a modified example of the supply opening 22a. As shown in Fig. 12, the inner peripheral surface of the supply opening 22c is a curved surface whose diameter gradually decreases toward the discharge opening 22b of the spool 22.

[0060] As described above, the oil control valve according to the first embodiment includes a housing 21 having a discharge port 21b for discharging hydraulic oil to the outside, a spool 22 supported on the inner peripheral surface of the housing 21 so as to be movable in the axial direction and having a discharge opening 22b opening on its outer peripheral surface for discharging hydraulic oil supplied to the interior to the discharge port 21b, and annular grooves 21d, 21e, and 21f formed on the inner peripheral surface of the housing 21 so as to face the discharge opening 22b. Therefore, the oil control valve according to the first embodiment can reduce the pressure of hydraulic oil acting on the spool 22 without increasing the outer diameter of the oil control valve. As a result, the oil control valve according to the first embodiment can eliminate imbalances in the balance of forces in the vertical or axial direction on the spool 22.

[0061] In the oil control valve according to the first embodiment, the annular grooves 21d, 21e, and 21f are positioned so that the groove width is greatest at the surface of the discharge opening 22b when the discharge port 21b and the discharge opening 22b are in communication with each other. Therefore, the oil control valve according to the first embodiment can easily promote the generation of the vortex 41 by using the annular grooves 21d, 21e, and 21f.

[0062] In the oil control valve according to the first embodiment, the inner circumferential surface of the supply opening 22 a is a tapered surface whose inner diameter gradually decreases toward the discharge opening 22 b. Therefore, the oil control valve according to the first embodiment can efficiently flow the hydraulic oil supplied through the supply opening 22 a toward the discharge opening 22 b and the communication portion 31. As a result, the oil control valve according to the first embodiment can further promote the generation of the vortex 41.

[0063] In the oil control valve according to the first embodiment, the inner peripheral surface of the supply opening 22c is a curved surface whose inner diameter gradually decreases toward the discharge opening 22b. Therefore, the oil control valve according to the first embodiment can efficiently flow the hydraulic oil supplied through the supply opening 22c toward the discharge opening 22b and the communication portion 31. As a result, the oil control valve according to the first embodiment can further promote the generation of the vortex 41.

[0064] In the oil control valve according to the first embodiment, the annular groove 21e is a V-shaped groove. Therefore, the oil control valve according to the first embodiment can easily promote the generation of the vortex 41 by using the annular groove 21e.

[0065] In the oil control valve according to the first embodiment, the annular groove 21f is a U-shaped groove. Therefore, the oil control valve according to the first embodiment can easily promote the generation of the vortex 41 by using the annular groove 21f.

[0066] It should be noted that within the scope of the present disclosure, the embodiments may be freely combined, or any component in each embodiment may be modified, or any component in each embodiment may be omitted.

[0067] The oil control valve according to the present disclosure is suitable for use in oil control valves and the like, because it can reduce the pressure of hydraulic oil acting on the spool by forming an annular groove on the inner peripheral surface of the housing.

[0068] 10 solenoid portion, 11 case, 12 terminal, 13 bracket, 13a annular portion, 13b mounting portion, 14 coil, 15 core, 16 plunger, 17 shaft, 18 boss, 20, 20A valve portion, 21 housing, 21a supply port, 21b, 21c discharge port, 21d, 21e, 21f annular groove, 22 spool, 22a, 22c, 22d supply opening, 22b discharge opening, 23 compression spring, 41, 42 vortex, 100 valve mounting member, 101 oil passage, 110 bolt.

Claims

1. A housing having a discharge port for discharging hydraulic fluid to the outside, A spool is supported on the inner circumferential surface of the housing so as to be movable in the axial direction, and has a discharge opening on its outer circumferential surface for discharging the hydraulic fluid supplied to the inside to the discharge port, The housing comprises an annular groove formed on the inner circumferential surface so as to face the discharge opening, The spool has a supply opening provided at the end of the spool for supplying hydraulic fluid into the spool, The inner diameter of the supply opening gradually decreases as it approaches the discharge opening. An oil control valve characterized by the following features.

2. The aforementioned annular groove is When the discharge port and the discharge opening are in communication, the discharge opening is positioned to surface in such a way that its groove width is maximized. The oil control valve according to feature 1.

3. The inner circumferential surface of the supply opening is a tapered surface in which the inner diameter gradually decreases as it approaches the discharge opening. The oil control valve according to feature 1.

4. The inner circumferential surface of the supply opening is a curved surface whose inner diameter gradually decreases as it approaches the discharge opening. The oil control valve according to feature 1.

5. The aforementioned annular groove is a V-shaped groove. The oil control valve according to feature 1.

6. The aforementioned annular groove is a U-shaped groove. The oil control valve according to feature 1.