JPH0135980Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to an endless ring for backup that increases pressure resistance and prevents damage to sealing rings used in sealing devices for hydraulic equipment such as pistons and cylinders.

2. Description of the Related Art In sealing devices for hydraulic equipment such as pistons and cylinders, the oil side of the lip around which an elastic tightening member such as a coil spring of a sealing ring fitted on the inner periphery of the cylinder is wound, is generally used for radial and axial direction. Due to the large hydraulic pressure acting on the piston, in conventional sealing devices where the sealing ring is formed only from an elastic material such as rubber, the lip is pressed against the piston shaft, deforming and damaging the piston, resulting in insufficient sealing. unable to perform functions. Therefore, conventionally, the air-side back of the lip of the sealing ring,
Specifically, it has been proposed that a back-up ring made of a rigid material such as metal or plastic is fitted onto the inner diameter surface of the sealing ring in order to prevent the lip from deforming. Since it is necessary to pass a shaft having an outer diameter larger than the inner diameter of the ring, it has been proposed that the ring is made expandable in the radial direction by cutting one point on the circumference of the ring.

Further, both ends formed by cutting the annular body engage each other in a concave and convex manner, so that relative displacement in the radial direction does not occur between the two ends when the outer peripheral side is restrained. A back-up spring is known from Japanese Utility Model Application Publication No. 58-65464.

However, with a back-up spring cut at one point on the circumference, there is a relative shift in the radial or axial direction, and the back-up spring may fall off when the back-up spring is attached to the seal ring or when the seal ring is assembled into the piston. When the sealing ring is used, the sealing ring may be damaged by biting into the sealing ring due to the relative deviation of the cut surface, and sometimes it may come into abnormal contact with the piston and wear out, impairing its sealing function. Further, even if the back-up spring is constructed as described in Japanese Utility Model Application Publication No. 58-65464, it is difficult to process the uneven portions at both ends, and damage to the sealing ring due to axial displacement cannot be prevented.

Means for Solving the Problem The above-mentioned problem is solved by an endless ring for backup in which a notch is formed on the circumferential surface of the annular body at at least one location on the circumference so that the annular body can expand and contract in the circumferential direction. .

Function: When the endless ring for back-up is assembled into a shaft while attached to a sealing ring, the notch extends in the circumferential direction to enlarge the inner diameter of the shaft so as to pass through the large diameter portion of the shaft. When the sealing device is completely installed in the sealing ring, the notch retracts to its original, substantially complete annular shape and exhibits pressure resistance against the hydraulic pressure acting on the sealing ring.

Examples The present invention will be explained in examples. In FIGS. 1 and 2, reference numeral 1 denotes an endless ring for back-up made of synthetic resin, and a notch 3 is formed on the circumferential surface of the annular body 2 at one location on the circumference so that the annular body 2 can expand and contract in the circumferential direction. is formed. The notches 3 are alternately provided on both end surfaces 2a and 2b of the annular body 2 so as to be offset in the circumferential direction. The depth H of the cut 3 is
By making the size smaller than the width W of the annular body 2 and appropriately changing the depth H of each cut 3 and the circumferential interval P, the amount of expansion in the circumferential direction is adjusted.

When the endless backup ring 1 is assembled into the shaft B with the sealing ring A attached as shown in FIG. It extends in the circumferential direction to enlarge its inner diameter, and when the sealing device is installed on the device, the cut portion contracts in the circumferential direction to form a part of the original substantially complete annular body 2, and the sealing Demonstrates pressure resistance against the hydraulic pressure acting on ring A.

FIG. 5 shows another embodiment in which the notches 3 are molded at the same time as the endless ring 1 for back-up is molded. In this case, the notch extends from the beginning in the circumferential direction as shown in the figure, and
a, 2b, and when the backup endless ring 1 is attached to the sealing ring, it is contracted in the circumferential direction and forms a part of an almost complete annular body 2 in the attached state.

FIG. 6 shows still another embodiment, in which notches 3 are provided alternately in the inner diameter surface 2c and outer diameter surface 2d at one location on the circumference of the annular body 2 so as to be offset in the circumferential direction. It can be expanded and contracted in the circumferential direction. The cut 3 may be molded at the same time when the endless backup ring 1 is molded so that it extends in the circumferential direction from the beginning.

The cut portion in each of the above embodiments is the annular body 2
Although it is formed at one location on the circumference, it may be formed at several locations, and the cross-sectional shape of the endless backup ring is not limited to that shown in the drawings.

Effects The present invention is an endless ring for back-up, in which a notch is formed on the circumferential surface of at least one place on the circumference of the annular body so that the annular body can expand and contract in the circumferential direction, and therefore has the following effects.

(a) Since it is an annular body without a cut part, the endless backup ring does not easily fall off when attaching the endless backup ring to the sealing ring or assembling the sealing ring into the shaft, making the work easier.

(b) Due to the stress that is applied when handling the sealing ring and the endless back-up ring, the two ends of the ring may become misaligned in the radial and axial directions as in the past.
It is possible to prevent the endless backup ring from deforming and damaging the sealing ring.

(c) When attached to the sealing ring, the notch contracts in the circumferential direction and forms part of an almost complete annular body, so the endless back-up ring does not deform due to the hydraulic pressure acting on the sealing ring. It is possible to exhibit sufficient pressure resistance with a small amount.

(d) It is easy to manufacture endless rings for backup.

[Brief explanation of the drawing]

Fig. 1 is a front view of the embodiment of the present invention, Fig. 2 is a side view of the embodiment of Fig. 1, Fig. 3 is a longitudinal cross-sectional view showing the state in which it is attached to a sealing ring, and Fig. 4 shows the notch. An enlarged view of the main part showing the state stretched in the circumferential direction,
FIG. 5 is a front view of a modified embodiment of the present invention, and FIG. 6 is a side view of essential parts of another embodiment. 1... Endless ring for backup, 2... Annular body, 3... Notch.

Claims (1)

[Claims for Utility Model Registration] (1) An endless ring for back-up, in which a notch is formed in at least one circumferential surface of the annular body so that the annular body can expand and contract in the circumferential direction. (2) The endless ring for backup according to claim 1, wherein the cuts are alternately formed on both end faces of the annular body so as to be offset in the circumferential direction. (3) The endless ring for backup according to claim 1, wherein the cuts are alternately formed on the inner peripheral surface and the outer peripheral surface of the annular body so as to be shifted in the circumferential direction.