Hydraulic actuator sealing device

Abstract

To provide a sealing device of a hydraulic actuator capable of improving durability of a seal lip.SOLUTION: A piston seal 1 comprises a piston 10 annular around an axial line x, and an annular inner peripheral seal lip 20 that is an elastic body attached to the piston 10 in order to seal a drive pressure chamber P1. A lip attachment part 13 of the piston 10 to which the inner peripheral seal lip 20 is attached has a curved surface 14.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a sealing device for a hydraulic actuator, and more particularly to a sealing device for a hydraulic actuator having a piston that is movable by hydraulic pressure within an annular driving pressure chamber. [Background technology]

[0002] An example of a hydraulic actuator is a hydraulic clutch having an annular piston and used in an automatic transmission of a vehicle such as an automobile. In a hydraulic clutch, the hydraulic pressure in an annular driving pressure chamber is increased in an annular space to press an annular piston against the clutch, thereby engaging the clutch, and the hydraulic pressure to the piston is released and the piston is returned by the force of a spring to disengage the clutch. In such a clutch piston mechanism, the oil in the driving pressure chamber is pressed against the piston by centrifugal force during driving, and the force of the spring that returns the piston when the clutch is disengaged is affected, and the piston may not be returned properly by the spring. For this reason, there has been a conventional hydraulic clutch in which a cancel plate is provided and a cancel pressure chamber that faces the driving pressure chamber via the piston is provided. In such a hydraulic clutch, the centrifugal force also acts on the oil in the cancel pressure chamber, thereby canceling the pressing force of the oil in the driving pressure chamber against the piston due to the centrifugal force.

[0003] The hydraulic clutch as described above is provided with a sealing device having an annular seal lip, and the inside of the piston hydraulic chamber is sealed by the seal lips provided on the outer and inner sides of the piston, and the outer side of the cancel pressure chamber is sealed by a seal lip provided on the outer side of the cancel plate (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 4701560 Summary of the Invention [Problem to be solved by the invention]

[0005] In the above-mentioned hydraulic clutch, when the hydraulic pressure generated in the piston hydraulic chamber for clutch engagement becomes high, the high pressure is applied to the seal lip, and it is conceivable that the seal lip may be damaged. For this reason, there is a demand for a sealing device of a conventional hydraulic clutch to have a highly pressure-resistant structure that will not damage the seal lip even if the hydraulic pressure acting on the seal lip is high.

[0006] The present invention has been made in consideration of the above-mentioned problems, and an object of the present invention is to provide a sealing device for a hydraulic actuator that can improve the pressure resistance of the seal lip. [Means for solving the problem]

[0007] In order to achieve the above-mentioned object, the sealing device of a hydraulic actuator according to the present invention is a sealing device of a hydraulic actuator having a piston that can move along an axis by hydraulic pressure in a driving pressure chamber which is an annular space, the sealing device being characterized in that it comprises the piston which is annular about the axis, an elastic body which is attached to the piston in order to seal the driving pressure chamber, and an inner peripheral seal lip which is annular about the axis, and the portion of the piston to which the inner peripheral seal lip is attached has a curved surface.

[0008] In the sealing device for a hydraulic actuator according to one aspect of the present invention, the curved surface is created when the piston is subjected to drawing.

[0009] In order to achieve the above-mentioned object, a sealing device for a hydraulic actuator according to the present invention is a sealing device for a hydraulic actuator including a piston that is movable along an axis by hydraulic pressure in a driving pressure chamber that is an annular space, the sealing device including the piston that is annular about the axis, and an inner circumferential seal lip that is an elastic body attached to the piston to seal the driving pressure chamber and is annular about the axis, the piston has a pair of side surfaces that are a pair of mutually opposing surfaces of the piston, and an inner circumferential end surface that is a surface facing the inner circumferential side between the pair of side surfaces, the inner circumferential seal lip is attached to the pair of side surfaces and the inner circumferential surface of the piston, and a thickness of a portion of the inner circumferential seal lip that is attached to the inner circumferential end surface of the piston is thinner than a thickness of a portion of the inner circumferential seal lip that is attached to the side surfaces of the piston.

[0010] In a sealing device of a hydraulic actuator according to one embodiment of the present invention, the piston has a step surface which forms a step between one of the pair of side surfaces and the inner end face, and the inner seal lip has a base which is attached to the pair of side surfaces, the inner end face, and the step surface of the piston, and a lip portion which protrudes from the base toward the inner side, and the lip portion is connected to the portion of the base which is attached to the step surface. Effect of the Invention

[0011] According to the sealing device for a hydraulic actuator according to the present invention, the pressure resistance of the seal lip can be improved. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a partial cross-sectional view taken along an axis, showing a schematic configuration of a hydraulic clutch as a hydraulic actuator including a piston seal as a sealing device of a hydraulic actuator according to a first embodiment of the present invention, and a canceller seal. [Diagram 2]1 is a cross-sectional view taken along an axis of a piston seal according to a first embodiment of the present invention. [Diagram 3] 3 is a partial cross-sectional view showing a cross section of one side of the piston seal shown in FIG. 2 with respect to an axis line. [Figure 4] 4 is a partially enlarged cross-sectional view showing an inner circumferential seal lip portion of the piston seal shown in FIG. 3. [Diagram 5] FIG. 4 is a partially enlarged cross-sectional view showing a cross section taken along the axis of a modified example of the piston seal according to the first embodiment of the present invention. [Figure 6] FIG. 6 is a partially enlarged cross-sectional view showing a part of a cross section along the axis of a piston seal according to a second embodiment of the present invention. [Figure 7] FIG. 11 is a partially enlarged cross-sectional view showing a part of a cross section along the axis of a piston seal according to a third embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a partial cross-sectional view along the axis x showing a schematic configuration of a hydraulic clutch 100 as a hydraulic actuator including a piston seal 1 as a sealing device of a hydraulic actuator according to a first embodiment of the present invention and a canceller seal 2. Hereinafter, for convenience of explanation, in a direction perpendicular to the axis x direction (hereinafter also referred to as a radial direction), the side in the direction away from the axis x (arrow a direction in FIG. 1) is referred to as the outer circumferential side, and the side in the direction approaching the axis x (arrow b direction in FIG. 1) is referred to as the inner circumferential side. In addition, in the axis x direction, the side in the direction of the arrow c (see FIG. 1) is referred to as the disconnecting side, and the side in the direction of the arrow d (see FIG. 1) is referred to as the connecting side.

[0014] As shown in Fig. 1, the hydraulic clutch 100 includes a piston mechanism 3 having a piston seal 1 and a canceller seal 2, a clutch cylinder 110 forming an annular space, an annular clutch hub 120, and a multi-plate clutch 130 for connecting or disconnecting the clutch cylinder 110 and the clutch hub 120. The clutch cylinder 110 is connected to the driving side and is rotatable around the axis x by the power of the driving side. The clutch hub 120 is connected to the driven side and is rotatable around the axis x by the power of the clutch cylinder 110 when the clutch 130 is connected. The piston mechanism 3 acts on the clutch 130 by moving the piston seal 1 in the direction of the axis x to connect and disconnect the clutch 130.

[0015] As shown in FIG. 1, the clutch cylinder 110 has an inner cylindrical portion 111 which is a cylindrical portion having an axis x as a central axis or an approximate central axis, a disk portion 112 which is a disk-shaped portion extending from the inner cylindrical portion 111 to the outer circumferential side and having the axis x as a central axis or an approximate central axis, and an outer cylindrical portion 113 which is a cylindrical portion extending from the disk portion 112 to the connection side on the outer circumferential side of the inner cylindrical portion 111 and having the axis x as a central axis or an approximate central axis. The clutch cylinder 110 also has an annular space 114 which extends along the axis x. The annular space 114 is a space surrounded by an outer circumferential surface 111a of the inner cylindrical portion 111, a side surface 112a of the disk portion 112 on the connection side, and an inner circumferential surface 113a of the outer cylindrical portion 113.

[0016] The clutch 130, which is a multi-plate clutch, has a plurality of drive plates 131 and a plurality of driven plates 132, and the drive plates 131 and the driven plates 132 are alternately arranged at intervals in the direction of the axis x. The drive plate 131 is supported at its outer circumferential portion by an inner circumferential surface 113a of the outer circumferential cylindrical portion 113 of the clutch cylinder 110. The driven plate 132 is supported at its inner circumferential portion by the clutch hub 120. The drive plate 131 is pushed in the connection direction by the action of the piston mechanism 3 and pressed against the driven plate 132, so as to be connected to the driven plate 132. When the drive plate 131 is no longer pressed by the piston mechanism 3, it moves in a direction away from the driven plate 132, and the connection with the driven plate 132 is cut off.

[0017] The clutch hub 120 is an annular member around the axis x, and has a cylindrical portion 121 that is a cylindrical portion with the axis x as its central axis or approximately its central axis. The driven plate 132 of the above-mentioned clutch 130 is fixed to the outer circumferential surface of this cylindrical portion 121 at its inner circumferential end.

[0018] A piston mechanism 3 is provided in a space 114 of the clutch cylinder 110, and the piston mechanism 3 forms an annular driving pressure chamber P1 and an annular cancel pressure chamber P2 in the space 114. As shown in FIG. 1, a piston seal 1 of the piston mechanism 3 is provided in the space 114 so as to be movable in the direction of the axis x within the space 114, and the piston seal 1 forms the driving pressure chamber P1 on its disconnecting side. Also, as shown in FIG. 1, the canceller seal 2 faces the piston seal 1 from the connecting side in the direction of the axis x, and forms a cancel pressure chamber P2, which is an annular space, between the canceller seal 2 and the piston seal 1. The cancel pressure chamber P2 is provided in the space 114 on the opposite side of the piston seal 1 from the driving pressure chamber P1.

[0019] As described later, the piston seal 1 has a seal lip, and the seal lip is in contact with the surface of the clutch cylinder 110 that forms the space 114 on the inner and outer circumferential sides, thereby sealing the driving pressure chamber P1. The seal lip is in contact with an inner peripheral surface 113a of an outer peripheral cylindrical portion 113 of the clutch cylinder 110 on its outer peripheral side, and in contact with an outer peripheral surface 111a of an inner peripheral cylindrical portion 111 of the clutch cylinder 110 on its inner peripheral side. The piston seal 1 is formed so as to be able to contact a drive plate 131 located on the disengagement side of the clutch 130 from the disengagement side when the piston seal 1 moves to the engagement side in the direction of the axis x.

[0020] The canceller seal 2 has a seal lip 2a, which contacts the piston seal 1 on the outer circumferential side, thereby sealing the outer circumferential side of the cancel pressure chamber P2. Specifically, the seal lip 2a of the canceller seal 2 contacts from the inner circumferential side with a cylindrically extending portion of the piston seal 1 on the outer circumferential side so as to contact the clutch 130. The canceller seal 2 is supported by the inner circumferential cylindrical portion 111 of the clutch cylinder 110 via a snap ring 141, and rotates together with the clutch cylinder 110.

[0021] The piston mechanism 3 has a return spring 140 which is a spring. The return spring 140 is provided in the cancel pressure chamber P2 and is sandwiched between the piston seal 1 and the canceller seal 2, biasing the piston seal 1 toward the cutting side in the direction of the axis x.

[0022] The clutch cylinder 110 is provided with a drive oil hole 115, which is a passage for supplying hydraulic oil into the drive pressure chamber P1 and discharging the hydraulic oil from the drive pressure chamber P1. The hydraulic oil is oil for controlling the hydraulic clutch 100, such as ATF (Automatic Transmission Fluid). The drive oil hole 115 opens to the drive pressure chamber P1 at the outer peripheral surface 111a of the inner cylindrical portion 111, and allows a supply source of hydraulic oil (not shown) to communicate with the drive pressure chamber P1. The clutch cylinder 110 is provided with a cancel oil hole 116, which is a passage for supplying hydraulic oil into the cancel pressure chamber P2 and discharging the hydraulic oil from the cancel pressure chamber P2. The cancel oil hole 116 opens to the cancel pressure chamber P2 at the outer peripheral surface 111a of the inner cylindrical portion 111, and allows a supply source of hydraulic oil (not shown) to communicate with the cancel pressure chamber P2.

[0023] In the hydraulic clutch 100, hydraulic oil (driving oil pressure) is generated in the driving pressure chamber P1 by supplying hydraulic oil into the driving pressure chamber P1 through the driving oil hole 115. This driving oil pressure moves the piston seal 1 to the connection side against the biasing force of the return spring 140, and the piston seal 1 comes into contact with the drive plate 131 of the clutch 130 and presses the drive plate 131 to the connection side. As a result, the drive plate 131 of the clutch 130 is pressed to the connection side, and each drive plate 131 is pressed against the corresponding driven plate 132. As a result, the clutch 130 is brought into an engaged state, and the power of the clutch cylinder 110 is transmitted to the clutch hub 120 via the clutch 130.

[0024] When the hydraulic oil in the driving pressure chamber P1 is discharged through the driving oil hole 115 from this connected state of the clutch 130, the driving oil pressure in the driving pressure chamber P1 is released and reduced, the biasing force of the return spring 140 becomes greater than the driving oil pressure, the piston seal 1 is moved to the disengaged side by the biasing force of the return spring 140, the drive plate 131 moves away from the driven plate 132, and the clutch 130 enters a disengaged state.

[0025] When the clutch cylinder 110 rotates, centrifugal force is applied to the hydraulic oil in the driving pressure chamber P1, and if this centrifugal force acts on the piston seal 1 and moves the piston seal 1, unintended operation of the clutch 130 will occur. For this reason, by supplying hydraulic oil to the cancel pressure chamber P2 via the cancel oil hole 116, centrifugal force is applied to the hydraulic oil in the cancel pressure chamber P2 in the same way as the hydraulic oil in the driving pressure chamber P1. As a result, the centrifugal force acting on the hydraulic oil in the cancel pressure chamber P2 cancels out the centrifugal force acting on the hydraulic oil in the driving pressure chamber P1, preventing unintended operation of the clutch 130.

[0026] A piston seal 1 according to an embodiment of the present invention will be described in detail below.

[0027] Fig. 2 is a cross-sectional view of a piston seal 1 according to a first embodiment of the present invention taken along an axis x, Fig. 3 is a partial cross-sectional view showing one side of the piston seal 1 shown in Fig. 2 with respect to the axis x, and Fig. 4 is a partially enlarged cross-sectional view of the piston seal 1. As shown in Figs. 2 to 4, the piston seal 1 includes a piston 10 having an annular shape around the axis x, and an inner peripheral seal lip 20 having an annular shape around the axis x, which is an elastic body attached to the piston 10 to seal the driving pressure chamber P1. The portion (lip attachment portion 13) of the piston 10 to which the inner peripheral seal lip 20 is attached has a curved surface 14. The configuration of the piston seal 1 will be specifically described below.

[0028] The piston 10 is an annular member made of metal and centered or approximately on the axis x, and has a pressure receiving portion 11 and a clutch pressing portion 12 as shown in Figs. 2 and 3. The pressure receiving portion 11 is an annular portion centered or approximately on the axis x, and in the hydraulic clutch 100 (see Fig. 1), it is a portion that receives the driving hydraulic pressure in the driving pressure chamber P1. The clutch pressing portion 12 is an annular portion centered or approximately on the axis x, and in the hydraulic clutch 100, it is a portion that presses the drive plate 131 of the clutch 130 toward the connecting side when the piston seal 1 is moved toward the connecting side (in the direction of the arrow d). The clutch pressing portion 12 extends from the outer peripheral end of the pressure receiving portion 11 toward the connecting side.

[0029] The pressure receiving portion 11 of the piston 10 has a pair of opposing surfaces, one of which is a driving pressure surface 11a and the other is a cancel pressure surface 11b. The driving pressure surface 11a is a surface facing the driving pressure chamber P1 side (cutting side) of the pressure receiving portion 11 of the piston 10, and the cancel pressure surface 11b is a surface facing the cancel pressure chamber P2 side (connecting side) of the pressure receiving portion 11 of the piston 10. The pressure receiving portion 11 of the piston 10 also has an inner peripheral end surface 11c as an inner peripheral surface extending between the inner peripheral end of the driving pressure surface 11a and the inner peripheral end of the cancel pressure surface 11b.

[0030] 3 and 4, the lip attachment portion 13 to which the inner peripheral seal lip 20 of the piston 10 is attached is located at the end portion on the inner peripheral side of the piston 10, and is also located at the end portion on the inner peripheral side of the pressure-receiving portion 11. As described above, the lip attachment portion 13 has a curved surface 14.

[0031] Specifically, the lip mounting portion 13 has a driving pressure surface end 13a which is a part of the inner peripheral end of the driving pressure surface 11a, a cancel pressure surface end 13b which is a part of the inner peripheral end of the cancel pressure surface 11b, and an inner peripheral end surface 11c. The driving pressure surface end 13a is along a plane perpendicular to the axis x, and is parallel or approximately parallel to the plane perpendicular to the axis x, for example, as shown in Figs. 3 and 4. The cancel pressure surface end 13b is along a plane perpendicular to the axis x, and is parallel or approximately parallel to the plane perpendicular to the axis x, for example, as shown in Figs. 3 and 4. The inner peripheral end surface 11c extends annularly along a cylindrical surface centered on the axis x, and is a cylindrical surface or approximately cylindrical surface centered on the axis x, for example, as shown in Figs. 3 and 4.

[0032] As shown in FIG. 4, the driving pressure surface 11a and the inner peripheral end surface 11c of the pressure receiving portion 11 of the piston 10 are connected to each other via a curved surface 14, and the driving pressure surface end 13a and the inner peripheral end surface 11c are connected to each other via the curved surface 14. On the other hand, the inner peripheral end surface 11c is directly connected to the cancel pressure surface 11b, that is, the cancel pressure surface end 13b. As shown in FIG. 4, the shape of the curved surface 14 is a shape that draws a curve in cross section, for example, a shape that draws a curve with a constant curvature in cross section. The shape of the curved surface 14 may be a shape that draws a curve in which curves of multiple curvatures are smoothly combined in cross section, or a shape that draws a line in which curves and straight lines are smoothly combined in cross section. The curved surface 14 is smoothly connected to the driving pressure surface end 13a and the inner peripheral end surface 11c. This curved surface 14 is also a part of the lip mounting portion 13.

[0033] The piston 10 may have various configurations as long as it has the lip mounting portion 13 described above, and may have various configurations according to the configuration of the hydraulic clutch.

[0034] The inner seal lip 20 is attached to the piston 10 at the lip attachment portion 13 as described above. As shown in Figs. 2 to 4, the inner seal lip 20 is an annular or approximately annular portion that protrudes from the inner end of the pressure-receiving portion 11 to the inner circumferential side and has the axis x as its center or approximately center. In the hydraulic clutch 100 (see Fig. 1), the inner seal lip 20 is formed so as to come into contact with the outer circumferential surface 111a of the inner cylindrical portion 111 of the clutch cylinder 110. In the hydraulic clutch 100, the inner seal lip 20 is formed so as to slide on the outer circumferential surface 111a of the inner cylindrical portion 111 when the piston seal 1 moves in the direction of the axis x.

[0035] The inner circumferential seal lip 20 has, for example, a base portion 21 and a lip portion 22. The base portion 21 is a portion attached to the piston 10 at the lip attachment portion 13, and the lip portion 22 is a portion protruding from the base portion 21. As shown in Figs. 2 to 4, the lip portion 22 protrudes from the base portion 21 to the inner circumferential side and the cutting side, and is formed so as to be in slidable contact with the outer circumferential surface 111a of the inner circumferential cylindrical portion 111 of the clutch cylinder 110, as described above.

[0036] The lip portion 22 extends from a portion (curved surface portion 21a) attached to the curved surface 14 of the lip attachment portion 13 of the base portion 21, and a root 22a of the lip portion 22 is connected to the curved surface portion 21a.

[0037] In addition, the base 21 has a driving pressure side portion 21b, which is a portion attached to the driving pressure surface end 13a of the lip mounting portion 13, a cancel pressure side portion 21c, which is a portion attached to the cancel pressure surface end 13b of the lip mounting portion 13, and an inner peripheral portion 21d, which is a portion attached to the inner peripheral end face 11c of the lip mounting portion 13.

[0038] As shown in FIG. 4, the thickness of the base 21 is, for example, the thinnest at the inner periphery 21d, the thickness t2 of the cancel pressure side 21c is thicker than the thickness t1 of the inner periphery 21d, and the thickness t3 of the driving pressure side 21b is thicker than the thickness of the cancel pressure side 21c. The thickness of the curved surface 21a is thicker than the thickness of the corresponding part of the base attached to the lip attachment part not having the curved surface 14. Note that, as shown in FIG. 4, the thickness of each part of the base 21 is the thickness in the direction perpendicular to the corresponding surface of the lip attachment part 13 in the cross section. Note that the thickness t3 of the driving pressure side 21b and the thickness t2 of the cancel pressure side 21c may be the same or approximately the same. Also, the thickness t2 of the cancel pressure side 21c and the thickness t1 of the inner periphery 21d may be the same or approximately the same. The relationship of the thicknesses of each part of the base 21 is not limited to the above-mentioned thicknesses.

[0039] The outer circumferential seal lip 30 is an elastic body attached to the piston 10 to seal the driving pressure chamber P1, and is an annular or annular part having the axis x as a center or approximately center thereof, protruding from the outer circumferential side part of the pressure receiving part 11 toward the outer circumferential side, as shown in Figs. 2 and 3. The outer circumferential seal lip 30 is formed in the hydraulic clutch 100 (see Fig. 1) so as to come into contact with the inner circumferential surface 113a of the outer circumferential cylindrical part 113 of the clutch cylinder 110. In the hydraulic clutch 100, the outer circumferential seal lip 30 is formed so as to slide on the inner circumferential surface 113a of the outer circumferential cylindrical part 113 when the piston seal 1 moves in the direction of the axis x.

[0040] The piston 10 is made of metal, and examples of the metal material of the piston 10 include stainless steel and SPCC (cold rolled steel), and mainly SPFH (hot rolled steel) and SAPH (hot rolled steel). The piston 10 is manufactured, for example, by pressing or forging a metal plate.

[0041] As described above, the inner seal lip 20 and the outer seal lip 30 are elastic bodies, and examples of the elastic material of the inner seal lip 20 and the outer seal lip 30 include rubber-like elastic materials. Examples of the rubber-like elastic material of the inner seal lip 20 and the outer seal lip 30 include synthetic rubbers such as nitrile rubber (NBR), hydrogenated nitrile rubber (H-NBR), acrylic rubber (ACM), fluororubber (FKM), silicone rubber, and styrene-butadiene rubber (SBR).

[0042] Next, the operation of the piston seal 1 having the above-mentioned configuration will be described. In use, as shown in Fig. 1, the inner circumferential seal lip 20 of the piston seal 1 contacts the outer circumferential surface 111a of the inner circumferential cylindrical portion 111 of the clutch cylinder 110, and the outer circumferential seal lip 30 contacts the inner circumferential surface 113a of the outer circumferential cylindrical portion 113 of the clutch cylinder 110, thereby sealing the driving pressure chamber P1. In use, when hydraulic oil is supplied into the driving pressure chamber P1 and the inside of the driving pressure chamber P1 becomes high pressure, high pressure is applied to the inner circumferential seal lip 20, causing the inner circumferential seal lip 20 to deform.

[0043] This deformation causes distortion and stress in the inner circumferential seal lip 20. That is, the lip portion 22 of the inner circumferential seal lip 20 deforms, causing distortion and stress in the lip portion 22 and the base portion 21. It is considered that a particularly large stress will be generated in the curved surface portion 21a to which the lip portion 22 is connected, but as described above, since the curved surface portion 21a of the base portion 21 is attached to the curved surface 14 of the piston 10, the stress is dispersed and stress concentration in the curved surface portion 21a can be suppressed.

[0044] Furthermore, since the thickness of the curved portion 21a is thicker than the thickness of the corresponding portion of the base attached to a lip attachment portion that does not have a conventional curved surface 14, even if the lip portion 22 deforms under high pressure and distortion occurs in the base 21, the distortion is dispersed in the thick curved portion 21a, and stress concentration can be suppressed.

[0045] In this way, the piston seal 1 can suppress the generation of large stress in the inner circumferential seal lip 20 even if the inner circumferential seal lip 20 is subjected to high pressure and deformed, thereby reducing the stress generated in the inner circumferential seal lip 20. Therefore, the inner circumferential seal lip 20 is less likely to be damaged even when subjected to high pressure, and the pressure resistance of the inner circumferential seal lip 20 is improved.

[0046] In addition, since the lip mounting portion 13 has a curved surface 14, the contact area between the base 21 and the piston 10 can be increased, and the strength of the inner seal lip 20 can be improved. This also increases the pressure resistance of the inner seal lip 20.

[0047] In addition, when the thickness t1 of the inner peripheral portion 21d of the base portion 21 is thinner than the other portions of the base portion 21 and the thickness t1 of the inner peripheral portion 21d is thin, the deformation of the lip portion 22 when the inner peripheral seal lip 20 is subjected to high pressure can be suppressed. This is because the thickness t1 of the inner peripheral portion 21d on the deformation direction side of the lip portion 22 is thin, so that the inner peripheral portion 21d is less likely to deform even when the lip portion 22 is subjected to high pressure, and acts as a resistance to the deformation of the lip portion 22. This reduces the distortion generated in the curved surface portion 21a to which the lip portion 22 is connected, reduces the stress generated in the curved surface portion 21a, and increases the pressure resistance of the inner peripheral seal lip 20. In this way, when the thickness t1 of the inner peripheral portion 21d is thin, the pressure resistance of the inner peripheral seal lip 20 can be increased.

[0048] As described above, according to the piston seal 1 according to the first embodiment of the present invention, the pressure resistance of the inner circumferential seal lip 20 can be improved.

[0049] Next, a modified example of the piston seal 1 according to the first embodiment of the present invention will be described. Fig. 5 is a partially enlarged cross-sectional view showing a modified example of the piston seal 1 according to the first embodiment of the present invention. In the piston seal 1 according to this modified example, the shape of the lip attachment part of the piston is different from the lip attachment part 13 described above, and the piston 10 has a pressure-receiving part 15 instead of the pressure-receiving part 11, and also has a lip attachment part 16 instead of the lip attachment part 13. In addition, in the piston seal 1 according to this modified example, the shape of the base part of the inner circumferential seal lip 20 is different from the base part 21 described above, and has a base part 23 instead of the base part 21.

[0050] As shown in FIG. 5, the lip attachment portion 16 of the piston seal 1 according to this modification is located at a curved portion 17 formed by drawing when the material is drawn to form the piston 10. As shown in FIG. 5, the curved portion 17 is a curved portion of the pressure receiving portion 15, and is a portion where the material is bent by drawing. The curved portion 17 is formed, for example, at the end of the inner circumference side of the pressure receiving portion 15. That is, the driving pressure surface 15a of the pressure receiving portion 15 is a curved surface at the end of the inner circumference side, and the cancel pressure surface 15b of the pressure receiving portion 15 is a curved surface at the end of the inner circumference side. An inner circumference end surface 15c extends between the end of the driving pressure surface 15a on the inner circumference side and the end of the cancel pressure surface 15b on the inner circumference side. The inner circumference end surface 15c is a surface along a plane perpendicular to the axis x, as shown in FIG. 5, for example, and more specifically, is a surface parallel or approximately parallel to the plane perpendicular to the axis x.

[0051] As shown in FIG. 5, the lip attachment portion 16 is an area formed by a curved surface 18, which is a part of the driving pressure surface 15a in the curved portion 17 of the pressure receiving portion 15, and a part of the inner peripheral end surface 15c. The shape of the curved surface 18 is a shape that draws a curve in cross section, similar to the shape of the curved surface 14 described above, for example, a shape that draws a curve with a constant curvature in cross section. The shape of the curved surface 18 may be a shape that draws a curve in which curves of multiple curvatures are smoothly combined in cross section, or a shape that draws a line in which curves and straight lines are smoothly combined in cross section. The curved surface 18 is a part on the tip side of the driving pressure surface 15a in the curved portion 17.

[0052] The base 23 of the inner circumferential seal lip 20 has a curved surface portion 23a which is a portion attached to the curved surface 18, and an inner circumferential portion 23b which is a portion attached to the inner circumferential end surface 15c. The lip portion 22 protrudes from the curved surface portion 23a. The inner circumferential portion 23b may be attached to the entire inner circumferential end surface 15c of the pressure receiving portion 15, or may extend beyond the inner circumferential end surface 15c to the cancel pressure surface 15b side.

[0053] In this modification, similarly to the above-described inner seal lip 20, the lip portion 22 is connected to the curved surface portion 23a, which is the portion attached to the curved surface 18 of the lip attachment portion 16, and even if high pressure is applied to the inner seal lip 20 in use, it is possible to suppress stress concentration in the inner seal lip 20. Also, the contact area between the base portion 23 and the lip attachment portion 16 is increased. Therefore, similarly to the above-described piston seal 1, it is possible to increase the pressure resistance of the inner seal lip 20.

[0054] Next, a piston seal 5 according to a second embodiment of the present invention will be described. Fig. 6 is a partially enlarged cross-sectional view showing a part of a cross section along the axis of the piston seal 5 according to the second embodiment of the present invention. The piston seal 5 according to the second embodiment of the present invention differs from the piston seal 1 according to the first embodiment of the present invention in the shape of the pressure-receiving part of the piston and the shape of the inner peripheral seal lip. Hereinafter, the same reference numerals will be used to designate the same configurations as the piston seal 1 according to the first embodiment of the present invention, and the description of those configurations having similar functions will be omitted, and different configurations will be described.

[0055] Like the piston seal 1, the piston seal 5 has a piston 40, an inner circumferential seal lip 50, and an outer circumferential seal lip 30. The piston 40 has a pressure-receiving portion 41 having a shape different from that of the pressure-receiving portion 11 of the piston 10 of the piston seal 1, but the other configuration is the same as that of the piston 10. As shown in FIG. 6, the pressure-receiving portion 41 of the piston 40 differs from the pressure-receiving portion 11 of the piston 10 in the shape of its tip, but the other configuration is the same as that of the pressure-receiving portion 11.

[0056] Specifically, as shown in Fig. 6, the pressure receiving portion 41 of the piston 40 has a driving pressure surface 41a and a cancel pressure surface 41b which are a pair of opposing surfaces (side surfaces). The driving pressure surface 41a is a surface facing the driving pressure chamber P1 side of the pressure receiving portion 41, and the cancel pressure surface 41b is a surface facing the cancel pressure chamber P2 side of the pressure receiving portion 41. The pressure receiving portion 41 also has an inner peripheral end surface 41c which is a surface facing the inner peripheral side between the driving pressure surface 41a and the cancel pressure surface 41b. Specifically, the inner peripheral end surface 41c extends between the inner peripheral end of the driving pressure surface 41a and the inner peripheral end of the cancel pressure surface 41b.

[0057] The inner seal lip 50 is attached to the driving pressure surface 41a, the cancel pressure surface 41b, and the inner end surface 41c of the piston 40. That is, the lip attachment portion 42, which is the portion to which the inner seal lip 50 of the piston 40 is attached, is located on the driving pressure surface 41a, the cancel pressure surface 41b, and the inner end surface 41c. Specifically, as shown in FIG. 6, the lip attachment portion 42 is located at the end portion on the inner periphery side of the pressure receiving portion 41, and is an area of ​​the driving pressure surface end 42a, which is the inner end portion of the driving pressure surface 41a, the cancel pressure surface end 42b, which is the inner end portion of the cancel pressure surface 41b, and the inner end surface 41c. The driving pressure surface end 42a is along a plane perpendicular to the axis x, and is parallel or approximately parallel to the plane perpendicular to the axis x, as shown in FIG. 6, for example. The cancel pressure surface end 42b is along a plane perpendicular to the axis x, and is parallel or approximately parallel to the plane perpendicular to the axis x, as shown in FIG. 6, for example. The inner peripheral end surface 41c extends annularly along a cylindrical surface centered on the axis x, and is, for example, as shown in FIG. 6, a cylindrical surface or a substantially cylindrical surface centered on the axis x.

[0058] The piston 40 may have various configurations as long as it has the lip mounting portion 42 described above, and may have various configurations according to the configuration of the hydraulic clutch.

[0059] The inner circumferential seal lip 50 has, for example, a base portion 51 and a lip portion 52. The base portion 51 is a portion attached to the lip attachment portion 42 of the piston 40, and the lip portion 52 is a portion protruding from the base portion 51.

[0060] The base 51 has a driving pressure side portion 51a, which is a portion attached to the driving pressure surface end 42a of the lip mounting portion 42, a cancel pressure side portion 51b, which is a portion attached to the cancel pressure surface end 42b of the lip mounting portion 42, and an inner peripheral portion 51c, which is a portion attached to the inner peripheral end face 41c of the lip mounting portion 42.

[0061] The lip portion 52 has a similar shape to the lip portion 22 described above, protrudes from the base portion 51 to the inner peripheral side and the cut side, and is formed so as to be in slidable contact with the outer peripheral surface 111a of the inner cylindrical portion 111 of the clutch cylinder 110. As shown in Fig. 6, the lip portion 52 extends from the inner peripheral end of the driving pressure side portion 51a of the base portion 51 and the cut side end of the inner peripheral portion 51c.

[0062] As shown in FIG. 6, the thickness (thickness t6) of the inner peripheral portion 51c, which is the portion attached to the inner peripheral end surface 41c of the inner peripheral seal lip 50, is thinner than the thickness (thickness t4) of the driving pressure side portion 51a, which is the portion attached to the driving pressure surface end 42a of the inner peripheral seal lip 50, and is also thinner than the thickness (thickness t5) of the cancel pressure side portion 51b, which is the portion attached to the cancel pressure surface end 42b of the inner peripheral seal lip 50. The thickness t4 of the driving pressure side portion 51a is thicker than the thickness t5 of the cancel pressure side portion 51b. The relationship of the thicknesses of the various portions of the base 51 is not limited to the above-mentioned thicknesses. Note that the thickness of each portion of the base 51 is the thickness in the direction perpendicular to the corresponding surface of the lip attachment portion 42 in the cross section, as shown in FIG. 6.

[0063] Next, the operation of the piston seal 5 having the above-mentioned configuration will be described. The piston seal 5 is attached as shown in Fig. 1 and in use, similarly to the piston seal 1. In use, as shown in Fig. 1, the inner circumferential seal lip 50 of the piston seal 5 contacts the outer circumferential surface 111a of the inner circumferential cylindrical portion 111 of the clutch cylinder 110, and the outer circumferential seal lip 30 contacts the inner circumferential surface 113a of the outer circumferential cylindrical portion 113 of the clutch cylinder 110, thereby sealing the driving pressure chamber P1. In use, when hydraulic oil is supplied into the driving pressure chamber P1 and the inside of the driving pressure chamber P1 becomes high pressure, high pressure is applied to the inner circumferential seal lip 50, causing the inner circumferential seal lip 50 to deform.

[0064] 6, the inner circumferential part 51c of the base 51 of the inner circumferential seal lip 50 is thin, which makes it possible to suppress deformation of the lip part 52. In this way, even if the inner circumferential seal lip 50 is deformed due to high pressure, the piston seal 5 suppresses deformation of the lip part 52, so that it is possible to suppress the generation of large stress in the inner circumferential seal lip 50 and reduce the stress generated in the inner circumferential seal lip 50. Therefore, the inner circumferential seal lip 50 is less likely to break even when subjected to high pressure, and the pressure resistance of the inner circumferential seal lip 50 is improved.

[0065] In this way, according to the piston seal 5 according to the second embodiment of the present invention, the pressure resistance of the inner circumferential seal lip 50 can be improved.

[0066] Next, a piston seal 6 according to a third embodiment of the present invention will be described. Fig. 7 is a partially enlarged cross-sectional view showing a part of a cross section along the axis of the piston seal 6 according to the third embodiment of the present invention. The piston seal 6 according to the third embodiment of the present invention differs from the piston seal 1 according to the first embodiment of the present invention in the shape of the pressure-receiving part of the piston and the shape of the inner peripheral seal lip. Hereinafter, the same reference numerals will be used to designate the same configurations as the piston seal 1 according to the first embodiment of the present invention, and the description of those configurations having similar functions will be omitted, and only different configurations will be described.

[0067] Like the piston seal 1, the piston seal 6 has a piston 45, an inner circumferential seal lip 55, and an outer circumferential seal lip 30. The piston 45 has a pressure-receiving portion 46 having a shape different from that of the pressure-receiving portion 11 of the piston 10 of the piston seal 1, but the other configuration is the same as that of the piston 10. As shown in FIG. 7, the pressure-receiving portion 46 of the piston 45 differs from the pressure-receiving portion 11 of the piston 10 in the shape of its tip, but the other configuration is the same as that of the pressure-receiving portion 11.

[0068] 7, the pressure receiving portion 46 of the piston 45 has a driving pressure surface 46a and a cancel pressure surface 46b which are a pair of opposing surfaces (side surfaces). The driving pressure surface 46a is a surface facing the driving pressure chamber P1 of the pressure receiving portion 46, and the cancel pressure surface 46b is a surface facing the cancel pressure chamber P2 of the pressure receiving portion 46. The pressure receiving portion 46 also has an inner peripheral end surface 46c which is a surface facing the inner peripheral side between the driving pressure surface 46a and the cancel pressure surface 46b.

[0069] As shown in FIG. 7, the pressure receiving portion 46 has a step surface 46d which is a portion (surface) forming a step between the driving pressure surface 46a and the inner peripheral end surface 46c. Specifically, the step surface 46d defines a portion recessed from the inner peripheral end surface 46c toward the inner peripheral side, and has, for example, a side surface 46e which is an annular surface extending along a plane perpendicular to the axis x, and a bottom surface 46f which is an annular surface around the axis x. The bottom surface 46f extends from the end of the outer peripheral side of the side surface 46e. The side surface 46e is, for example, a surface parallel or approximately parallel to the plane perpendicular to the axis x, and the bottom surface 46f is, for example, a cylindrical surface or an approximately cylindrical surface with the axis x as the central axis. The end of the inner peripheral side of the driving pressure surface 46a does not reach the position of the inner peripheral end surface 46c in the radial direction, and is connected to the end of the cut side of the bottom surface 46f of the step surface 46d. The inner peripheral end surface 46c is connected at its cut-side end to the inner peripheral end of the side surface 46e of the step surface 46d, and is connected at its connected-side end to the inner peripheral end of the cancel pressure surface 41b.

[0070] The inner circumferential seal lip 55 is attached to the driving pressure surface 46a, the cancel pressure surface 46b, the inner circumferential end surface 46c, and the step surface 46d of the piston 45. In other words, the lip attachment portion 47, which is the portion of the piston 45 where the inner circumferential seal lip 55 is attached, is located on the driving pressure surface 46a, the cancel pressure surface 46b, the inner circumferential end surface 46c, and the step surface 46d.

[0071] Specifically, as shown in FIG. 7, the lip attachment portion 47 is located at the end of the inner periphery of the pressure receiving portion 46, and is an area including a driving pressure surface end 47a which is an inner periphery end portion of the driving pressure surface 46a, a cancel pressure surface end 47b which is an inner periphery end portion of the cancel pressure surface 46b, an inner periphery end surface 46c, and a step surface 46d. The driving pressure surface end 47a is along a plane perpendicular to the axis x, and is parallel or approximately parallel to the plane perpendicular to the axis x, as shown in FIG. 7, for example. The cancel pressure surface end 47b is along a plane perpendicular to the axis x, and is parallel or approximately parallel to the plane perpendicular to the axis x, as shown in FIG. 7, for example. The inner periphery end surface 46c extends annularly along a cylindrical surface centered on the axis x, and is a cylindrical surface or approximately cylindrical surface centered on the axis x, as shown in FIG. 7, for example.

[0072] The piston 45 may have various configurations as long as it has the lip attachment portion 47 described above, and may have various configurations according to the configuration of the hydraulic clutch.

[0073] The inner circumferential seal lip 55 has, for example, a base portion 56 and a lip portion 57. The base portion 56 is a portion attached to the lip attachment portion 47 of the piston 45, and the lip portion 57 is a portion protruding from the base portion 56.

[0074] The base 56 has a driving pressure side portion 56a which is a portion attached to the driving pressure surface end 47a of the lip mounting portion 47, a cancel pressure side portion 56b which is a portion attached to the cancel pressure surface end 47b of the lip mounting portion 47, an inner peripheral portion 56c which is a portion attached to the inner peripheral end face 46c of the lip mounting portion 47, and a step portion 56d which is a portion attached to the step surface 46d of the lip mounting portion 47.

[0075] The lip portion 57 has a similar shape to the lip portion 22 described above, protrudes from the base portion 56 to the inner peripheral side and the cutting side, and is formed so as to be in slidable contact with the outer peripheral surface 111a of the inner peripheral tube portion 111 of the clutch cylinder 110. As shown in Fig. 7, the lip portion 57 is connected to the step portion 56d of the base portion 56, and for example, a root 57a of the lip portion 57 is connected to the cutting side end of the step portion 56d and the inner peripheral side end of the driving pressure side portion 56a.

[0076] As shown in FIG. 7, the thickness (thickness t9) of the inner peripheral portion 56c, which is the portion attached to the inner peripheral end surface 46c of the inner peripheral seal lip 55, is thinner than the thickness (thickness t7) of the driving pressure side portion 56a, which is the portion attached to the driving pressure surface end 47a of the inner peripheral seal lip 55, and is also thinner than the thickness (thickness t8) of the cancel pressure side portion 56b, which is the portion attached to the cancel pressure surface end 47b of the inner peripheral seal lip 55. The thickness t7 of the driving pressure side portion 56a is thicker than the thickness t8 of the cancel pressure side portion 56b. The thickness (thickness t10) of the step portion 56d, which is the portion attached to the step surface 46d of the inner peripheral seal lip 55, is thicker than the thickness t7 of the driving pressure side portion 56a. The relationship of the thicknesses of the various portions of the base portion 56 is not limited to the above-mentioned thicknesses. For example, the thickness t10 of the step portion 56d may be the same as or approximately the same as the thickness t7 of the driving pressure side portion 56a. The thickness of each portion of the base 56 is measured in a direction perpendicular to the corresponding surface of the lip attachment portion 47 in cross section, as shown in FIG.

[0077] Next, the operation of the piston seal 6 having the above-mentioned configuration will be described. The piston seal 6 is attached as shown in Fig. 1 and in use, similarly to the piston seal 1. In use, as shown in Fig. 1, the inner circumferential seal lip 55 of the piston seal 6 contacts the outer circumferential surface 111a of the inner circumferential cylindrical portion 111 of the clutch cylinder 110, and the outer circumferential seal lip 30 contacts the inner circumferential surface 113a of the outer circumferential cylindrical portion 113 of the clutch cylinder 110, thereby sealing the driving pressure chamber P1. In use, when hydraulic oil is supplied into the driving pressure chamber P1 and the inside of the driving pressure chamber P1 becomes high pressure, high pressure is applied to the inner circumferential seal lip 55, causing the inner circumferential seal lip 55 to deform.

[0078] The base 56 of the inner seal lip 55 has a step portion 56d, and the step portion 56d is supported by the step surface 46d of the piston 45. Therefore, when the lip portion 57 deforms, the lip portion 57 is supported by the step surface 46d of the piston 45 via the step portion 56d of the base 56. The support of the step surface 46d can suppress the deformation of the lip portion 57. In this way, even if the inner seal lip 55 is subjected to high pressure, the piston seal 6 suppresses the deformation of the lip portion 57, so that it is possible to suppress the generation of large stress in the inner seal lip 55 and reduce the stress generated in the inner seal lip 55. Therefore, the inner seal lip 55 is less likely to break even when subjected to high pressure, and the pressure resistance of the inner seal lip 55 is high.

[0079] In this way, according to the piston seal 6 according to the third embodiment of the present invention, the pressure resistance of the inner circumferential seal lip 55 can be improved.

[0080] Although the embodiment of the present invention has been described above, the present invention is not limited to the piston seals 1, 5, and 6 as sealing devices for hydraulic actuators according to the above-mentioned embodiment of the present invention, but includes all aspects included in the concept of the present invention and the scope of the claims. In addition, each configuration may be appropriately and selectively combined so as to achieve at least a part of the above-mentioned problems and effects. For example, the shape, material, arrangement, size, etc. of each configuration in the above-mentioned embodiment may be appropriately changed depending on the specific use of the present invention.

[0081] The piston seals 1, 5, and 6 as sealing devices for a hydraulic actuator according to the present invention are applied to a hydraulic clutch, but the application of the sealing device for a hydraulic actuator according to the present invention is not limited to this, and the present invention is applicable to all other configurations in which the effects of the present invention can be utilized. [Explanation of symbols]

[0082] 1, 5, 6... piston seal, 2... canceller seal, 2a... seal lip, 3... piston mechanism, 4... elastic body portion, 10, 40, 45... piston, 11, 15, 41, 46... pressure receiving portion, 11a, 15a, 41a, 46a... driving pressure surface, 11b, 15b, 41b, 46b... cancel pressure surface, 11c, 15c, 41c, 46c... inner peripheral end surface, 12... clutch push Pressure portion, 12a... inner peripheral surface, 13, 16, 42, 47... lip mounting portion, 13a, 42a, 47a... driving pressure surface end, 13b, 42b, 47b... cancel pressure surface end, 14, 18... curved surface, 17... curved portion, 20, 50, 55... inner peripheral seal lip, 21, 23, 51, 56... base portion, 21a, 23a... curved surface portion, 21b, 51a, 56a... driving pressure side portion, 21c, 51b, 56b...cancel pressure side portion, 21d, 23b, 51c, 56c...inner peripheral portion, 22, 52, 57...lip portion, 22a, 57a...root, 30...outer peripheral seal lip, 46d...step surface, 46e...side surface, 46f...bottom surface, 56d...step portion, 100...hydraulic clutch, 110...clutch cylinder, 111...inner peripheral cylindrical portion, 111a...outer peripheral surface, 112...disk portion, 112a...side surface, 113...outer peripheral cylindrical portion, 113a...inner peripheral surface, 114...space, 115...drive oil hole, 116...cancel oil hole, 120...clutch hub, 121...cylindrical portion, 130...clutch, 131...drive plate, 132...driven plate, 140...return spring, 141...snap ring, P1...drive pressure chamber, P2...cancel pressure chamber, t1 to t10...thickness

Claims

[Claim 1] A sealing device for a hydraulic actuator having a piston that is movable along an axis by hydraulic pressure in a driving pressure chamber that is an annular space, The piston is annular about the axis; an elastic body attached to the piston to seal the driving pressure chamber, the elastic body having an annular inner peripheral seal lip around the axis; The piston has a pair of side surfaces which are a pair of surfaces of the piston facing away from each other, and an inner peripheral end surface which is a surface facing the inner peripheral side between the pair of side surfaces, The inner circumferential seal lip is attached to the pair of side surfaces and the inner circumferential surface of the piston, a thickness of a portion of the inner circumferential seal lip attached to an inner circumferential end surface of the piston is thinner than a thickness of a portion of the inner circumferential seal lip attached to the side surface of the piston, the piston has a step surface that forms a step between one of the pair of side surfaces and the inner circumferential end surface, the inner circumferential seal lip has a base portion which is attached to the pair of side surfaces, the inner circumferential end surface, and the step surface of the piston, and a lip portion which is a portion which protrudes from the base portion to the inner circumferential side, A sealing device for a hydraulic actuator, characterized in that the lip portion is connected to a portion of the base that is attached to the step surface.

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