JPH0532875U - Seal member for hydraulic cylinder - Google Patents

Abstract

(57) [Abstract] [Purpose] A cross section in a direction parallel to the axis has a substantially U-shape with an inner ring portion and an outer ring portion, and the U-shaped opening is on the liquid chamber side. A seal member for a hydraulic cylinder that is installed in a pre-pressed state between the bottom of the annular groove on the outer peripheral surface of the piston and the inner peripheral surface of the cylinder bore so that it is located on the outer peripheral side due to the negative pressure of the hydraulic chamber when filling the hydraulic fluid (EN) Provided is a seal member capable of preventing outside air from being sucked into a liquid chamber due to the ring portion being pulled toward the inner peripheral side and preventing liquid leakage due to fatigue of the outer peripheral side ring portion. A plurality of deformation suppressing portions 52 for suppressing deformation of the outer peripheral ring portion 48 toward the inner peripheral side are provided between the outer peripheral ring portion 48 and the inner peripheral ring portion 46 at predetermined circumferential intervals. It is provided integrally with.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a seal member used in a hydraulic cylinder, and in particular, it is mounted in a preloaded state between the bottom of an annular groove formed on the outer peripheral surface of the piston of the hydraulic cylinder and the inner peripheral surface of the cylinder bore. The present invention relates to an annular seal member whose cross section in a direction parallel to the axis is substantially U-shaped.

[0002]

[Prior Art]

 In a hydraulic cylinder, generally, when a hydraulic pressure is supplied to a liquid chamber in a cylinder bore, a piston slidably fitted in the cylinder bore is driven, and the inner circumference of those cylinder bores is driven. A seal member is provided to prevent liquid leakage between the surface and the outer peripheral surface of the piston. One type of this seal member has an inner peripheral side ring part and an outer peripheral side ring part located on the outer peripheral side thereof integrally, and has a substantially U-shaped cross section in a direction parallel to the axis. It is mounted in a preloaded state between the bottom of the annular groove formed on the outer peripheral surface of the piston and the inner peripheral surface of the cylinder bore so that the tips of the ring portion and the outer peripheral ring portion are located on the liquid chamber side. , The inner peripheral ring portion is pressed against the bottom of the annular groove by the liquid pressure supplied from the liquid chamber between the inner peripheral ring portion and the outer peripheral ring portion, and the outer peripheral ring portion contacts the inner peripheral surface of the cylinder bore. There is a type in which the outer peripheral surface of the piston and the inner peripheral surface of the cylinder bore are liquid-tightly sealed by being pressed. For example, a seal member for a wheel cylinder for a drum brake described in Japanese Utility Model Laid-Open No. 60-173729 previously filed and published by the present applicant is that.

[0003]

[Problems to be solved by the device]

 By the way, in a hydraulic cylinder such as a wheel cylinder for a drum brake as described above, the liquid chamber is evacuated in advance to a negative pressure, and the working liquid is filled in the liquid chamber in the negative pressure state. However, due to the negative pressure, the outer peripheral ring part of the seal member is pulled toward the liquid chamber side and the inner peripheral side, so that the sealability between the outer peripheral ring part and the inner peripheral surface of the cylinder bore is maintained appropriately. There was a risk that it could not be done and the outside air would be sucked into the liquid chamber.

Further, in the hydraulic cylinder provided with the seal member as described above, the ring portion on the outer peripheral side of the seal member is caused to settle toward the inner peripheral side due to long-term use, use conditions, and the like. The pressing force against the inner peripheral surface of the cylinder bore of the outer peripheral side ring part could not be obtained sufficiently, and as a result, the sealing effect of the outer peripheral side ring part was deteriorated and liquid leakage could occur.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a cross section in a direction parallel to an axis having an inner peripheral side ring portion and an outer peripheral side ring portion. Is substantially U-shaped, and is mounted in a pre-loaded state between the bottom of the annular groove on the outer peripheral surface of the piston and the inner peripheral surface of the cylinder bore so that the U-shaped opening is located on the liquid chamber side. A seal member for a vehicle, which can prevent intake of outside air into the liquid chamber due to negative pressure in the liquid chamber when the hydraulic fluid is filled, and the outer ring can be prevented from being sucked into the liquid chamber. It is to provide a seal member capable of preventing liquid leakage due to

[0006]

[Means for Solving the Problems]

 The gist of the present invention for achieving the above object is to provide a hydraulic pressure for driving a piston slidably fitted in the cylinder bore when the hydraulic pressure is supplied to the hydraulic chamber in the cylinder bore. In the cylinder, the inner peripheral side ring portion and the outer peripheral side ring portion located on the outer peripheral side thereof are integrally formed, and the cross section in the direction parallel to the axis is substantially U-shaped. The outer peripheral surface of the piston is mounted between the bottom of the annular groove formed on the outer peripheral surface of the piston and the inner peripheral surface of the cylinder bore so that the tip of the side ring portion is located on the liquid chamber side in a preloaded state. A seal member for liquid-tightly sealing between the inner peripheral surface of the cylinder bore and the inner peripheral surface of the cylinder bore, the inner peripheral surface of the outer peripheral ring portion being provided between the outer peripheral ring portion and the inner peripheral ring portion. To suppress deformation to the side It is meant to include integrally form suppressing portion.

[0007]

[Effect of action and device]

 With this configuration, the deformation suppressing portion integrally provided on the seal member between the outer peripheral ring portion and the inner peripheral ring portion suppresses the outer peripheral ring portion from deforming toward the inner peripheral side. Therefore, when the negative pressure is created in the liquid chamber prior to filling the hydraulic chamber with the hydraulic fluid, the negative pressure deforms the outer ring portion being pulled inward. This can be effectively prevented by the restraining part, and thereby the sealing property between the outer peripheral side ring part and the inner peripheral surface of the cylinder bore can be suitably maintained, and suction of outside air into the liquid chamber due to negative pressure can be suitably prevented. On the other hand, the presence of the deformation suppressing portion can effectively suppress the outer peripheral side ring portion from sagging toward the inner peripheral side due to long-term use or use conditions. It can be maintained favorably, and it is It can preferably prevent liquid leakage by.

[0008]

【Example】

 An embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 3 is a view showing a main part of a drum brake equipped with a wheel cylinder as a hydraulic cylinder having a seal member of the present invention. In the figure, a pair of brake shoes 12 and 14 are supported on a backing plate 10 by shoe hold down devices 16 and 18 so as to be able to expand each other. The opposite ends of the brake shoes 12, 14 are in contact with the side surfaces of the anchor 20 fixed on the backing plate 10, and the other ends of the brake shoes 12, 14 are on the backing plate 10. Are engaged with both ends of the wheel cylinder 22 fixed to the. Incidentally, 24 is a shoe return spring.

The wheel cylinder 22 includes a cylinder body 28 having a cylinder bore 26 that opens in both axial directions, a pair of pistons 30 and 32 slidably fitted in the cylinder bore 26, and the pistons. And a compression coil spring 34 provided between the pistons 30, 32, and the ends of the pistons 30, 32 opposite to the compression coil spring 34 side engage with the other ends of the brake shoes 12, 14, respectively. The liquid chamber 36 is formed by the surfaces of the pistons 30 and 32 facing each other and the inner peripheral surface of the cylinder bore 26. The fluid chamber 36 is pre-filled with brake fluid, and when a brake operating force is applied to increase the fluid pressure in the fluid chamber 36, the pistons 30 and 32 are pushed out in a direction in which they are separated from each other. The shoes 12, 14 are expanded against each other against the urging force of the shoe return spring 24, so that the brake shoes 12, 14 are pressed against the inner peripheral surface of the rotating drum (not shown) for braking. When the above-mentioned brake fluid is filled in the fluid chamber 36, for example, the inside of the fluid chamber 36 is evacuated to a predetermined negative pressure, and the brake fluid is injected into the fluid chamber 36 in the negative pressure state. In addition, in FIG. 2, 38 and 40 are dust covers.

Since the pistons 30 and 32 have the same configuration as each other, the following description will be given for only one piston 30. An annular groove 42 is formed on the outer peripheral surface of the piston 30, and an annular seal member 44 made of an elastic material such as rubber is provided in the annular groove 42 and the bottom of the annular groove 42 and the inner peripheral surface of the cylinder bore 26. It is installed in a pre-loaded state between and. As shown in FIGS. 1 and 2, the seal member 44 includes an inner peripheral side ring portion 46 whose length in a direction parallel to the axis is substantially the same as the width dimension of the annular groove 42, and the inner peripheral side ring portion 46. The outer peripheral side ring portion 48, which is provided on the outer peripheral side and whose length in the direction parallel to the axis is shorter than the inner peripheral side ring portion 46 by a predetermined dimension, is opposed to the inner peripheral side ring portion 46 and the outer peripheral side ring portion 48. And a connecting portion 50 that connects to each other on one end side facing each other, and has a substantially U-shaped cross section in a direction parallel to the axis. Between the inner peripheral side ring part 46 and the outer peripheral side ring part 48 of the seal member 44, for example, four deformation suppressing parts 52 are arranged at substantially equal intervals in the circumferential direction. It is provided integrally with the ring portion 48 and the connecting portion 50, and these deformation suppressing portions 52 can suppress the deformation of the outer peripheral ring portion 48 toward the inner peripheral side.

As shown in FIGS. 3 and 4, the sealing member 44 is arranged so that the other end portions (tip portions) of the inner peripheral side ring portion 46 and the outer peripheral side ring portion 48 are located on the liquid chamber 36 side. It is mounted in the annular groove 42, and the inner peripheral surface of the inner peripheral ring portion 46 is brought into close contact with the bottom portion of the annular groove 42 according to its elastic return force, and the outer peripheral surface of the outer peripheral ring portion 48 is attached to the cylinder bore. It is closely attached to the inner peripheral surface of 26. When the hydraulic pressure in the liquid chamber 36 is increased, the hydraulic pressure is transmitted to the annular space between the inner peripheral side ring portion 46 and the outer peripheral side ring portion 48 of the seal member 44, and the annular space is formed. By the hydraulic pressure of the inner peripheral side ring portion 46 being strongly pressed against the bottom of the annular groove 42 and the outer peripheral side ring portion 48 being strongly pressed against the inner peripheral surface of the cylinder bore 26, the outer peripheral surface of the piston 30 and the cylinder bore 26 are It is designed to be liquid-tightly sealed with the inner peripheral surface. When the ring portions 46 and 48 are thus pressed against the bottom of the annular groove 42 and the inner peripheral surface of the cylinder bore 26 by the hydraulic pressure, the deformation suppressing portion 52 is extended in the radial direction of the seal member 44. Accordingly, even in the portion where the deformation suppressing portion 52 is provided, the inner peripheral side ring portion 46 and the outer peripheral side ring portion 48 can be suitably pressed against the bottom portion of the annular groove 42 and the inner peripheral surface of the cylinder bore 26 by hydraulic pressure. It is possible to obtain a sufficient sealing property. The thickness dimension of the deformation suppressing portion 52 in the circumferential direction of the seal member 44 and the height dimension from the connecting portion 50, and the arrangement interval and the number of the deformation suppressing portions 52 in the circumferential direction of the seal member 44 are as described above. Even in the portion where the portion 52 is provided, sufficient sealing performance of the inner peripheral side ring portion 46 and the outer peripheral side ring portion 48 due to hydraulic pressure is obtained, and the inner peripheral surface of the outer peripheral side ring portion 48 due to a negative pressure described later is obtained. The material and hardness of the seal member 44, the negative pressure in the liquid chamber 36, the liquid chamber 36, and the inner wall of the outer ring portion 48 can be effectively prevented from being pulled inward and the inner ring of the outer ring portion 48 can be effectively prevented from being set. It is determined in advance in relation to the hydraulic pressure supplied to the valve, the preload in the mounted state of the seal member 44, and the like. Note that in FIG. 4, the gap between the outer peripheral surface of the piston 30 and the inner peripheral surface of the cylinder bore 26 is drawn larger than it actually is.

Here, in the conventional case in which the deformation suppressing portion 52 as described above is not provided, a negative pressure is applied to the inside of the liquid chamber 36 prior to filling the brake fluid into the liquid chamber 36. At this time, the negative pressure in the liquid chamber 36 pulls the outer peripheral side ring portion 48 toward the inner peripheral side on the liquid chamber 36 side, so that the pressing force of the outer peripheral side ring portion 48 against the inner peripheral surface of the cylinder bore 26 is increased. As shown in FIG. 9, there is a slight gap between the outer peripheral side ring portion 48 and the inner peripheral surface of the cylinder bore 26, which causes a gap between the outer peripheral side ring portion 48 and the inner peripheral surface of the cylinder bore 26. There is a possibility that the sealability cannot be maintained properly and the outside air is sucked into the liquid chamber 36. Further, in the above-described conventional case, due to the long-term use of the seal member 44, the operating conditions, etc., the outer peripheral side ring portion 48 is depressed toward the inner peripheral side and the inside of the cylinder bore 26 of the outer peripheral side ring portion 48. A sufficient pressing force cannot be obtained on the peripheral surface, which may reduce the sealing effect of the outer ring portion 48 and cause liquid leakage.

On the other hand, according to the present embodiment, the outer peripheral ringing is performed by the four deformation suppressing portions 52 provided between the inner peripheral side ring portion 46 and the outer peripheral side ring portion 48 of the seal member 44. The deformation of the portion 48 is suppressed so that the outer ring portion 48 is pulled inward by the negative pressure in the liquid chamber 36 by the deformation suppressing portion 52. Since it can be effectively prevented, the sealability between the outer peripheral side ring portion 48 and the inner peripheral surface of the cylinder bore 26 can be preferably maintained, and the suction of the outside air into the liquid chamber 36 due to the negative pressure can be preferably prevented. On the other hand, the presence of the deformation suppressing portion 52 can effectively prevent the outer peripheral side ring portion 48 from sagging toward the inner peripheral side due to long-term use or use conditions. Therefore, the outer peripheral side ring portion 48 has a sealing effect. Can be maintained appropriately Therefore, it is possible to preferably prevent the liquid leakage due to the fatigue of the outer peripheral side ring portion 48.

Further, according to the present embodiment, since the deformation suppressing portion 52 can be integrally formed at the same time as the molding of the seal member 44, the above effect can be achieved without increasing the manufacturing man-hour and time of the seal member 44. There is an advantage that can be obtained.

In the above embodiment, the deformation suppressing portion 52 has substantially the same thickness in the radial direction of the seal member 44. However, as shown in FIG. 5, for example, as shown in FIG. A deformation suppressing portion 54 may be provided whose thickness decreases toward the ring portion 46, or, as shown in FIG. 6, from the inner peripheral side ring portion 46 and the outer peripheral side ring portion 48 toward the intermediate portion thereof. It is also possible to provide the deformation suppressing portion 56 whose thickness becomes smaller accordingly.

Further, in the above-described embodiment, as shown in FIGS. 7 and 8, for example, as shown in FIGS. 7 and 8, a portion located on the outer peripheral side ring portion 48 side of the deformation suppressing portion 52 of the seal member 44 and connected to the connecting portion 50. A groove 58 having a predetermined depth that penetrates the deformation suppressing portion 52 in the thickness direction is formed on the surface on the opposite side in consideration of the bending margin of the outer peripheral side ring portion 48 when the seal member 44 is attached, and the seal member 44 is formed. The groove 58 may be eliminated and the same state as in the case of FIG. 4 may be formed in a state in which the groove 58 is mounted between the bottom of the annular groove 42 and the inner peripheral surface of the cylinder bore 26. With this configuration, by providing the deformation suppressing portion 52, the preload in the mounted state of the seal member 44 and thus the pressing force of the outer peripheral side ring portion 48 against the inner peripheral surface of the cylinder bore 26 becomes unnecessarily large, and the piston 30 moves. It is possible to preferably prevent the sliding resistance from increasing, and by providing the deformation suppressing portion 52, the pressing force of the outer peripheral side ring portion 48 against the inner peripheral surface of the cylinder bore 26 is reduced by the hydraulic pressure. Can be prevented easily and surely.

Further, in the above embodiment, the deformation suppressing portion 52 is formed integrally with the seal member 44, but the seal member including the inner peripheral side ring portion 46, the outer peripheral side ring portion 48, and the connecting portion 50. The member that constitutes the deformation suppressing portion may be integrally fixed to the main body.

Further, in the above-described embodiment, four deformation suppressing portions 52 are provided in the circumferential direction of the seal member 44, but it is not always necessary, and for example, a plurality of deformation suppressing portions 52 other than four may be provided. Alternatively, it is possible to provide one annular deformation suppressing portion. When this annular deformation suppressing portion is provided, an annular groove is formed in the portion located on the outer peripheral side ring portion side of the annular deformation suppressing portion in the same manner as in the case of FIG. 7 and FIG. The Rukoto.

Further, in the above embodiment, the case where the present invention is applied to the sealing member of the wheel cylinder of the leading trailing type drum brake has been described, but the sealing member of the wheel cylinder of the drum brake other than the leading trailing type is described. Of course, the present invention can also be applied to a seal member for a hydraulic cylinder other than the drum brake wheel cylinder.

In addition, the present invention can be variously modified without departing from the spirit thereof.

[Brief description of drawings]

1 is a cross-sectional view of the seal member of FIG. 2 taken along line I-I.

FIG. 2 is a view showing an example of a sealing member for a hydraulic cylinder of the present invention.

3 is a view showing a main part of a drum brake provided with a wheel cylinder that is an example of a hydraulic cylinder having the seal member of FIG. 2, and is a view in which a part is cut away.

FIG. 4 is a view corresponding to an enlarged view of a main part of the wheel cylinder of FIG.

5 is a view showing another example of the seal member of the present invention and is a view corresponding to the main part of FIG. 2. FIG.

FIG. 6 is a view showing still another example of the seal member of the present invention and is a view corresponding to the main part of FIG. 2.

FIG. 7 is a view showing still another example of the seal member of the present invention and corresponds to FIG.

8 is a cross-sectional view of the seal member of FIG. 7 taken along line VIII-VIII.

9 is a view showing an example of a state in which the outer peripheral side ring portion is pulled in due to the negative pressure of the liquid chamber in the conventional hydraulic cylinder seal member, and is a diagram corresponding to FIG. 4. FIG.

[Explanation of symbols]

 22 Wheel Cylinder (Hydraulic Cylinder) 26 Cylinder Bore 30, 32 Piston 36 Liquid Chamber 42 Annular Groove 44 Sealing Member 46 Inner Circumferential Side Ring Part 48 Outer Peripheral Side Ring Part 52, 54, 56 Deformation Suppression Section

Claims (1)

[Scope of utility model registration request] 1. In a hydraulic cylinder in which a piston slidably fitted in the cylinder bore is driven by supplying hydraulic pressure to a liquid chamber in the cylinder bore, an inner peripheral side ring portion and an outer peripheral side thereof. Has an outer peripheral side ring portion integrally located at, and has a substantially U-shaped cross section in a direction parallel to the axis,
In a preload state between the bottom of the annular groove formed in the outer peripheral surface of the piston and the inner peripheral surface of the cylinder bore so that the tips of the inner peripheral side ring portion and the outer peripheral side ring portion are located on the liquid chamber side. A seal member that is mounted to seal the outer peripheral surface of the piston and the inner peripheral surface of the cylinder bore in a liquid-tight manner, and is provided between the outer peripheral side ring portion and the inner peripheral side ring portion. A sealing member for a hydraulic cylinder, which integrally includes a deformation suppressing portion for suppressing deformation of the outer peripheral side ring portion toward the inner peripheral side.