Control Valve

Abstract

To provide a control valve capable of restraining clogging caused by impurities.SOLUTION: A control valve includes: a sleeve; a spool which is stored in the sleeve and is moved between a first position for opening a flow passage of fluid supplied to a device and a second position for closing the flow passage; and a coil spring which is stored in the sleeve and energizes the spool to the first position or the second position. The spool includes an engagement portion provided in an area which is brought into contact with one end of the coil spring, and the engagement portion is engaged with the end of the coil spring so that the spool is rotated together with the end of the coil spring in accordance with the change of a length of the coil spring at least either when the spool is moved from the first position to the second position or when the spool is moved from the second position to the first position.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] In hydraulic devices, a control valve may be used to control the hydraulic pressure. As the device is used, the liquid, such as oil, flowing through the control valve may contain impurities, such as metal particles caused by bearing wear. If such impurities become clogged in the control valve, the control valve may not operate normally (e.g., valve stick). Therefore, various configurations have been proposed to suppress clogging of the control valve by impurities (e.g., Patent Documents 1-3). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2005-226695 A [Patent Document 2] JP 2007-292162 A [Patent Document 3] JP 2000-303864 A Summary of the Invention [Problem to be solved by the invention]

[0004] As described above, it is desirable for the control valve to have a configuration capable of suppressing clogging by impurities.

[0005] An object of the present invention is to provide a control valve capable of suppressing clogging by impurities. [Means for solving the problem]

[0006] One embodiment of the present invention is a control valve for controlling hydraulic pressure supplied to a device, comprising: Sleeves and a spool received within the sleeve and configured to move between a first position that opens a flow path for liquid to be delivered to the device and a second position that closes the flow path; a coil spring received within the sleeve and biasing the spool toward the first position or the second position; Equipped with the spool includes an engagement portion provided at a portion that comes into contact with one end of the coil spring, The engagement portion engages the end of the coil spring such that the spool rotates with the end of the coil spring as the length of the coil spring changes when the spool moves from the first position toward the second position or when the spool moves from the second position toward the first position. Effect of the Invention

[0007] According to the present invention, clogging with impurities can be suppressed. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a cross-sectional view showing an embodiment of a control valve when a spool is in a first position. [Diagram 2] FIG. 2 is a cross-sectional view of the control valve when the spool is in a second position. [Diagram 3] FIG. 3 shows a side view and a front view of the coil spring when unloaded. [Figure 4] FIG. 4 shows a side view and a front view of a coil spring in compression. [Diagram 5] 5 is an enlarged cross-sectional view of the spool taken along the line VV in FIG. [Figure 6] FIG. 6 is an enlarged side view of the second seal land. [Figure 7] FIG. 7 is a schematic diagram illustrating the forces acting on an impurity. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. The specific dimensions, materials, values, etc. shown in the embodiment are merely examples for easy understanding, and do not limit the present invention unless otherwise specified. In the specification and drawings, elements having substantially the same functions and configurations are given the same reference numerals to avoid repeated explanation. In addition, elements not directly related to the present invention are not shown.

[0010] Fig. 1 is a cross-sectional view showing a control valve 100 according to an embodiment when a spool 2 is in a first position P1. Fig. 2 is a cross-sectional view showing a control valve 100 when a spool 2 is in a second position P2. Note that in Figs. 1 and 2, the spool 2 is shown in a side view.

[0011] Referring to FIG. 1, the control valve 100 is used to control hydraulic pressure in a hydraulic device. For example, the control valve 100 can be used for hydraulic devices, such as clutches, in automobiles. However, the application of the control valve 100 is not limited to automobiles, and it can also be used in various machines that use hydraulic pressure, such as heavy machinery, aircraft, ships, etc. In this embodiment, oil is used as the pressure transmission medium. However, in other embodiments, liquids other than oil may be used as the pressure transmission medium.

[0012] The control valve 100 includes a sleeve 1 , a spool 2 , a coil spring 3 , and a plate 4 .

[0013] The sleeve 1 includes a generally cylindrical inner wall 11. The inner wall 11 defines a generally cylindrical space 12. In this disclosure, unless otherwise indicated, the central axial direction, radial direction, and circumferential direction of the inner wall 11 may be simply referred to as the central axial direction, radial direction, and circumferential direction, respectively. In the central axial direction, a first end 1A of the sleeve 1 is open. In the central axial direction, a second end 1B of the sleeve 1 is closed.

[0014] The sleeve 1 includes a first opening 13, a second opening 14, and a third opening 15 in the order of proximity to the first end 1A in the central axis direction. Each of the openings 13, 14, and 15 radially penetrates a side wall of the sleeve 1 and connects the space 12 to the outside of the sleeve 1. The openings 13, 14, and 15 are spaced apart from each other along the central axis direction. The openings 13, 14, and 15 are provided between an approximate middle position of the sleeve 1 and the second end 1B in the central axis direction. The first opening 13 is connected to a device to which hydraulic pressure is supplied. Each of the second opening 14 and the third opening 15 is connected to a source of oil. The second opening 14 and the third opening 15 may be connected to the same source or may be connected to separate sources.

[0015] The sleeve 1 includes a slit 16. The slit 16 penetrates radially through both sides of the side wall of the sleeve 1 with the space 12 in between. In the central axial direction, the slit 16 is provided near the first end 1A. The plate 4 is inserted into the slit 16. The plate 4 divides the space 12 in the central axial direction.

[0016] The spool 2 is accommodated in the sleeve 1 and configured to move within the sleeve 1. The spool 2 includes a first shaft 21, a first seal land 22, a second shaft 23, a second seal land 24, and a protrusion 25, in that order from the first end 1A of the sleeve 1 in the central axial direction. For example, the first shaft 21, the first seal land 22, the second shaft 23, the second seal land 24, and the protrusion 25 are integrally formed and disposed on the same central axis. In other embodiments, at least one of the first shaft 21, the first seal land 22, the second shaft 23, the second seal land 24, or the protrusion 25 may be formed separately and later connected to the remaining portion.

[0017] The first shaft 21 has a generally cylindrical shape. The first shaft 21 has a diameter smaller than the diameter of the inner wall 11 of the sleeve 1. The first shaft 21 includes a first end 2A of the spool 2 in the central axial direction. A coil spring 3 is disposed around the first shaft 21.

[0018] The first seal land 22 is connected to the first shaft 21. The first seal land 22 has a cylindrical shape. The first seal land 22 has a diameter that is approximately the same as or slightly smaller than the diameter of the inner wall 11 of the sleeve 1. The first seal land 22 slides within the inner wall 11. The first seal land 22 seals the inner wall 11 and partitions the space 12 in the central axial direction.

[0019] In the central axial direction, the plate 4 and the first seal land 22 define a first space 12a. The first space 12a is a part of the space 12. The first space 12a accommodates the coil spring 3 and the first shaft 21.

[0020] The coil spring 3 is disposed concentrically on the inner wall 11. In this embodiment, the coil spring 3 is a compression coil spring. For example, the coil spring 3 has an outer diameter that is approximately the same as or smaller than the diameter of the first seal land 22.

[0021] The coil spring 3 biases the spool 2 toward the first position P1. Specifically, the first end 3A of the coil spring 3 contacts the plate 4, and the second end 3B contacts the end face of the first seal land 22. The coil spring 3 is constantly compressed in the central axial direction by the plate 4 and the first seal land 22, and biases the first seal land 22 and the entire spool 2 toward the second end 1B of the sleeve 1 in the central axial direction. The second end 2B of the spool 2, i.e., the protrusion 25, contacts the second end 1B of the sleeve 1 by the biasing force of the coil spring 3. In this embodiment, the position shown in FIG. 1 is the first position P1 of the spool 2.

[0022] The first end 3A of the coil spring 3 is rotationally constrained against the plate 4 by friction. For example, the surface of the plate 4 may be roughened to increase the coefficient of friction. In other embodiments, the first end 3A may be fixed against the plate 4.

[0023] The first seal land 22 includes a plurality of grooves (engagement portions) 22b on an end surface 22a that contacts the coil spring 3. The grooves 22b engage with the second end 3B of the coil spring 3. The engagement between the grooves 22b and the coil spring 3 will be described in detail later.

[0024] The second shaft 23 is connected to the first seal land 22. The second shaft 23 has a cylindrical shape. The second shaft 23 has a diameter smaller than the diameter of the inner wall 11 of the sleeve 1.

[0025] The second seal land 24 is connected to the second shaft 23. The second seal land 24 has a cylindrical shape. The second seal land 24 has a diameter that is approximately the same as or slightly smaller than the diameter of the inner wall 11 of the sleeve 1. The second seal land 24 slides within the inner wall 11. The second seal land 24 seals against the inner wall 11 and separates the space 12.

[0026] In the central axial direction, the first seal land 22 and the second seal land 24 define a second space 12b. The second space 12b is a part of the space 12. The second space 12b accommodates a second shaft 23. In addition, at the first position P1, the second space 12b communicates with the second opening 14. Therefore, the second space 12b is filled with oil supplied through the second opening 14.

[0027] In the central axial direction, the second seal land 24 and the second end 1B of the sleeve 1 define a third space 12c. The third space 12c is a part of the space 12. The third space 12c accommodates the protrusion 25. The third space 12c is also in constant communication with the third opening 15. Therefore, the third space 12c is filled with oil supplied through the third opening 15.

[0028] The protrusion 25 is connected to the second seal land 24. The protrusion 25 has a generally frusto-conical shape. The protrusion 25 has an outermost diameter that is smaller than a diameter of the inner wall 11 of the sleeve 1. The protrusion 25 contacts the second end 1B of the sleeve 1 in the central axial direction at a first position P1.

[0029] The lengths of the second shaft 23, the second seal land 24, and the projection 25 in the central axial direction are determined so that the first seal land 22 does not overlap the first opening 13 or at least partially opens the first opening 13 at the first position P1. Also, the lengths of the second seal land 24 and the projection 25 in the central axial direction are determined so that the second seal land 24 at least partially opens the second opening 14 at the first position P1.

[0030] 1 opens a flow path for oil to be supplied to a device (not shown) to which hydraulic pressure is to be supplied. Specifically, in the first position P1, the second seal land 24 at least partially opens the second opening 14. Thus, in the first position P1, the oil supply source communicates with the device to which hydraulic pressure is to be supplied via the second opening 14, the second space 12b, and the first opening 13. Thus, in the first position P1, oil is supplied from the supply source to the second opening 14 and then sent to the device via the second space 12b and the first opening 13. With this configuration, hydraulic pressure is supplied to the device.

[0031] When the control valve 100 as described above stops the supply of hydraulic pressure, the hydraulic pressure to the second opening 14 is reduced, and the hydraulic pressure to the third opening 15 is increased. Therefore, the hydraulic pressure in the third space 12c increases, and the hydraulic pressure in the second space 12b decreases. When the hydraulic pressure in the third space 12c exceeds the biasing force of the coil spring 3, the spool 2 further compresses the coil spring 3 from the initial compressed state, and the coil spring 3 slides toward the first end 1A of the sleeve 1.

[0032] 2, when the first end 2A of the spool 2 comes into contact with the plate 4, the spool 2 stops. In this embodiment, the position shown in FIG. 2 is the second position P2 of the spool 2. The second position P2 closes the flow path of the oil supplied to the device. Specifically, as shown in FIG. 2, in the second position P2, the second seal land 24 opens the second opening 14. Therefore, the flow path connecting the supply source and the device is blocked by the second seal land 24. With this configuration, the supply of hydraulic pressure to the device is stopped.

[0033] Next, a detailed description will be given of the engagement between the groove 22b and the coil spring 3. First, the coil spring 3 will be described in detail.

[0034] 3 is a side view and a front view showing the coil spring 3 when unloaded. As described above, the coil spring 3 includes a first end 3A and a second end 3B. For example, in FIG. 3, as shown in the front view on the right, the second end 3B is located on a horizontal axis.

[0035] FIG. 4 shows a side view and a front view of the coil spring 3 during compression. As described above, the first end 3A of the coil spring 3 is constrained in the rotational direction relative to the plate 4 by friction. When the coil spring 3 is compressed in this state, the pitch angle of the coil spring 3 is reduced, so that the second end 3B of the coil spring 3 is rotated clockwise around the central axis as shown in the front view on the right. Note that for better understanding, the rotation angle of the second end 3B is exaggerated in FIG. 4 and may not be accurate. In contrast, when the coil spring 3 returns from the compressed state shown in FIG. 4 to the unloaded state shown in FIG. 3, the second end 3B rotates counterclockwise. Note that if the coil spring 3 is wound in the reverse direction, the second end 3B rotates in the opposite direction to the above direction.

[0036] In this embodiment, by utilizing this property of the coil spring 3, the spool 2 is rotated together with the second end 3B of the coil spring 3 at least when the spool 2 moves from the first position P1 toward the second position P2 or when the spool 2 moves from the second position P2 toward the first position P1.

[0037] FIG. 5 is an enlarged cross-sectional view of the spool 2 taken along the line VV in FIG. 2, showing the end face 22a of the first seal land 22. FIG. 6 is an enlarged side view of the first seal land 22. Referring to FIG. 5, the end face 22a includes a plurality of grooves (engagement portions) 22b as described above. For example, in this embodiment, 18 grooves 22b are formed. However, the number of grooves 22b is not limited to this, and for example, a single groove 22b may be formed, or a plurality of grooves 22b other than 18 may be formed. The plurality of grooves 22b are formed along the circumferential direction.

[0038] In this embodiment, the groove 22b is configured to engage with the second end 3B of the coil spring 3 when the spool 2 moves from the first position P1 to the second position P2, and not to engage with the second end 3B when the spool 2 moves from the second position P2 to the first position P1. Specifically, referring to Fig. 6, each groove 22b includes a first surface 22c and a second surface 22d.

[0039] The first surface 22c is, for example, a plane. In other embodiments, the first surface 22c may be a curved surface. As shown in FIG. 5, the first surface 22c is parallel or approximately parallel to the radial direction. Also, as shown in FIG. 6, the first surface 22c is parallel or approximately parallel to the central axis direction. That is, the first surface 22c is perpendicular or approximately perpendicular to the circumferential direction. Therefore, the first surface 22c engages with the second end 2B of the coil spring 3 in the circumferential direction. In this embodiment, the first surface 22c is formed in a direction that contacts the rotating second end 3B of the coil spring 3 when the spool 2 moves from the first position P1 to the second position P2, that is, when the coil spring 3 is further compressed from the initial compressed state. For example, the second end 3B of the coil spring 3 may be bent parallel to the central axis direction so that the first surface 22c can easily capture the second end 3B.

[0040] The second surface 22d is, for example, a flat surface. In other embodiments, the second surface 22d may be a curved surface. As shown in FIG. 5, the second surface 22d is parallel or approximately parallel to the radial direction. In contrast, as shown in FIG. 6, the second surface 22d is inclined with respect to the central axis direction. That is, the second surface 22d is inclined with respect to the circumferential direction. The angle of the second surface 22d with respect to the central axis is designed so that when the spool 2 returns from the second position P2 to the first position P1, that is, when the coil spring 3 returns to the initial compressed state, the second end 3B of the coil spring 3 is not captured by the second surface 22d. Therefore, when the spool 2 returns from the second position P2 to the first position P1, the second end 3B of the coil spring 3 slides on the second surface 22d.

[0041] For example, the dimensions of the groove 22b can be determined so as to adequately capture the second end 3B of the coil spring 3. For example, these dimensions may be determined based on at least one parameter such as the diameter and spring constant of the material of the coil spring 3.

[0042] As described above, a plurality of sawtooth grooves 22b are continuously formed in the circumferential direction on the end face 22a of the first seal land 22 of the spool 2. The grooves 22b are configured to engage with the second end 3B of the coil spring 3 when the spool 2 moves from the first position P1 to the second position P2, and not to engage with the second end 3B when the spool 2 returns from the second position P2 to the first position P1. That is, the grooves 22b function like a ratchet.

[0043] 1, when the control valve 100 stops supplying hydraulic pressure as described above, the hydraulic pressure in the third space 12c is increased. When the hydraulic pressure in the third space 12c exceeds the biasing force of the coil spring 3, the spool 2 further compresses the coil spring 3 from the initial compressed state, and the coil spring 3 slides toward the first end 1A of the sleeve 1.

[0044] Referring to FIG. 2, when the coil spring 3 is further compressed from the initial compressed state, the first end 3A of the coil spring 3 is constrained in the rotational direction by the frictional force between the first end 3A and the plate 4 and does not rotate. In contrast, the second end 3B of the coil spring 3 is a free end and rotates around the central axis. The rotating second end 3B is captured by any of the grooves 22b of the first seal land 22 and abuts against the first surface 22c of the groove 22b. Therefore, the second end 3B applies a rotational force to the first seal land 22. Therefore, the first seal land 22 and the entire spool 2 rotate together with the second end 3B of the coil spring 3. That is, the spool 2 rotates while sliding toward the first end 1A of the sleeve 1.

[0045] FIG. 7 is a schematic diagram illustrating the forces Fa and Fc applied to the impurities C, showing a part of the sleeve 1 and the spool 2. When the oil contains impurities C, such as metal particles of microns due to the wear of the bearing, the impurities C can get stuck between the sleeve 1 and the sliding spool 2. However, in the control valve 100, the spool 2 rotates together with the second end 3B of the coil spring 3 while sliding, so that the impurities C are subjected to a circumferential force Fc in addition to the force Fa in the central axis direction. Therefore, the force Fa in the central axis direction that draws the impurities C between the spool 2 and the sleeve 1 is dispersed. Therefore, the impurities C are less likely to be drawn between the spool 2 and the sleeve 1 along the central axis direction. Therefore, the clogging of the impurities C can be suppressed. In addition, the plastic deformation of the sleeve 1 and the spool 2 can be suppressed.

[0046] Referring to FIG. 1, when the control valve 100 resumes the supply of hydraulic pressure, the hydraulic pressure to the third opening 15 is reduced. Therefore, the hydraulic pressure in the third space 12c is reduced. When the hydraulic pressure in the third space 12c is reduced below the biasing force of the coil spring 3, the spool 2 slides toward the second end 1B of the sleeve 1 due to the biasing force of the coil spring 3. In this case, the second end 3B of the coil spring 3 slides on the second surface 22d and is not captured by the groove 22b, and therefore does not apply a rotational force to the first seal land 22. Therefore, although the second end 3B of the coil spring 3 rotates, the first seal land 22 does not rotate. Therefore, the spool 2 slides toward the second end 1B without rotating. In this case, only the force Fa in the central axis direction is applied to the impurity C. Therefore, the impurity C is subjected to a force in a different direction when the spool 2 moves from the first position P1 to the second position P2 and when the spool 2 returns from the second position P2 to the first position P1. Therefore, the impurity C moves along a different path when the spool 2 moves from the first position P1 to the second position P2 and when the spool 2 returns from the second position P2 to the first position P1. This makes it possible to reduce the impurity C from repeatedly damaging the same places of the sleeve 1 and the spool 2.

[0047] The control valve 100 according to the embodiment described above includes a sleeve 1, a spool 2 accommodated in the sleeve 1 and configured to move between a first position P1 for opening a flow path of oil supplied to the device and a second position P2 for closing the flow path, and a coil spring 3 accommodated in the sleeve 1 and biasing the spool 2 toward the first position P1. The spool 2 includes a groove 22b provided in a portion that contacts the second end 3B of the coil spring 3. The groove 22b engages with the second end 2B of the coil spring 3 such that the spool 2 rotates together with the second end 2B of the coil spring 3 as the length of the coil spring 3 changes when the spool 2 moves from the first position P1 to the second position P2. Therefore, since the spool 2 rotates together with the second end 3B of the coil spring 3 when moving from the first position P1 to the second position P2, a force Fc in the circumferential direction is applied to the impurities C in the oil in addition to a force Fa in the central axis direction. Therefore, the impurities C are less likely to be drawn into the gap between the spool 2 and the sleeve 1 along the central axial direction, and thus clogging of the gap with the impurities C can be suppressed.

[0048] Furthermore, in the control valve 100, the engagement portion between the spool 2 and the coil spring 3 is the groove 22b provided in the spool 2. Therefore, the spool 2 can be rotated with a simple structure.

[0049] Also, in the control valve 100, the groove 22b engages with the second end 3B of the coil spring 3 only when the spool 2 moves from the first position P1 to the second position P2. Therefore, when the spool 2 returns from the second position P2 to the first position P1, the spool 2 does not rotate, and only the force Fa in the central axis direction is applied to the impurities C in the oil. Therefore, the impurities C are applied with forces in different directions when the spool 2 moves from the first position P1 to the second position P2 and when the spool 2 returns from the second position P2 to the first position P1. Therefore, the impurities C move along different paths in these cases. This can reduce the impurities C from repeatedly damaging the same parts of the sleeve 1 and the spool 2.

[0050] Furthermore, in the control valve 100, the groove 22b engages with the second end 3B when the spool 2 moves from the first position P1, which opens the flow path, to the second position P2, which closes the flow path. The impurities C are likely to be drawn between the sleeve 1 and the spool 2 when the flow path is closed. In the above case, the spool 2 rotates when the flow path is closed, so clogging by the impurities C can be efficiently suppressed.

[0051] Although the embodiments have been described above with reference to the accompanying drawings, the present invention is not limited to such embodiments. It is clear that a person skilled in the art can think of various modified or altered examples within the scope of the claims, and it is understood that such examples also naturally belong to the technical scope of the present invention.

[0052] For example, in the above embodiment, the control valve 100 is configured so that the coil spring 3 biases the spool 2 toward the first position P1 at which the oil flow path is opened. However, in other embodiments, the control valve 100 may be configured so that the coil spring 3 biases the spool 2 toward the second position P2 at which the oil flow path is closed.

[0053] In the above embodiment, the groove 22b engages with the second end 3B of the coil spring 3 only when the spool 2 moves from the first position P1 to the second position P2. However, in another embodiment, the groove 22b may engage with the second end 3B of the coil spring 3 both when the spool 2 moves from the first position P1 to the second position P2 and when the spool 2 moves from the second position P2 to the first position P1. In this case, for example, the second end 3B of the coil spring 3 may be bent parallel to the central axis, and the groove 22b may be formed to include a pair of opposing flat surfaces parallel to the central axis. Alternatively, the second end 3B of the coil spring 3 may be fixed to the end surface 22a of the first seal land 22 by a known fixing method such as crimping.

[0054] In another embodiment, the groove 22b may engage with the second end 3B of the coil spring 3 only when the spool 2 returns from the second position P2 to the first position P1. In this case, for example, the second end 3B of the coil spring 3 may be bent parallel to the central axis, the first surface 22c may be inclined with respect to the central axis, and the second surface 22d may be formed parallel or approximately parallel to the central axis.

[0055] Also, in the above embodiment, the engagement portion includes the groove 22b provided in the end face 22a of the first seal land 22. However, in other embodiments, the engagement portion may include a protrusion protruding from the end face 22a in the central axis direction. [Explanation of symbols]

[0056] 1 Sleeve 2 Spools 3 Coil spring 3B Second end of coil spring 22b Groove (engaging part) 100 Control valve P1 1st position of spool P2 spool second position

Claims

1. A control valve for controlling the hydraulic pressure supplied to the device, Sleeves and a spool received within the sleeve and configured to move between a first position that opens a flow path for liquid to be delivered to the device and a second position that closes the flow path; a coil spring received within the sleeve and biasing the spool toward the first position or the second position; Equipped with the spool includes an engagement portion provided at a portion that comes into contact with one end of the coil spring, the engagement portion engages the end of the coil spring such that the spool rotates together with the end of the coil spring as a length of the coil spring changes at least one of when the spool moves from the first position toward the second position and when the spool moves from the second position toward the first position. Control valve.

2. The control valve according to claim 1 , wherein the engagement portion includes a groove or a protrusion provided on the spool.

3. 3. The control valve according to claim 1, wherein the engagement portion engages with the end of the coil spring either when the spool moves from the first position toward the second position or when the spool moves from the second position toward the first position.

4. 4. The control valve of claim 3, wherein the engagement portion engages the end of the coil spring when the spool moves from the first position toward the second position.

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