JPH04169375A - Seal structure - Google Patents

Abstract

PURPOSE:To prevent the scars on a seal from being deepened by the scars on a rod by reciprocating a seal holder with the fluid pressure applied to the seal holder and the energizing force of an energizing member, and rotating the seal holder via the coupling of a long hole and a pin. CONSTITUTION:When pressure oil is fed to a chamber A on the right side of a piston 32 and the piston 32 is moved to the left, a seal holder 35 is moved to the right by the hydraulic force and retreated while compressing a rubber ball 44, and the seal holder 35 is rotated via the coupling of a pin 41 and a long hole 27. When pressure oil is fed to a chamber B on the left side of the piston 32 and the piston 32 is moved to the right, the pressure of the chamber A is low, the seal holder 35 is moved to the left by the elastic force of the rubber ball 44 and rotated via the coupling of the long hole 27 and the pin 41. When there are scars on the outer periphery of a rod 31, the range where scars are generated on a seal 38 is widened, however the depth of the scars is made shallow, and the occurrence of an oil leakage from the seal 38 is prevented.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a seal structure used in a hydraulic cylinder of a power steering device or the like.

[Conventional technology]

FIG. 5 is a schematic diagram of the power steering device. Fifth
In the figure, l is the handle, 2 is the steering shaft, 3 is the pinion provided on the steering shaft 2C, and 5 is the steering shaft.
is a hydraulic cylinder, 6 is a rod, and 7 is a rack formed at the tip of the rod 6 and meshes with the pinion 3. The outer periphery of the rod 6 is sealed by a seal structure 8.9 having a seal (not shown). Note that 11 is a switching valve fixed to the steering shaft, 12 and 13 are electromagnetic switching valves, 15 is an electromagnetic throttle valve, 16 is a motor, and 17 is a pump.

[Problem to be solved by the invention]

By the way, in the above-mentioned hydraulic cylinder 5, the rod 6 performs reciprocating motion, but does not perform rotational motion. Therefore, if the rod 6 is damaged, the same part of the seal of the seal structure 8° 9 can be replaced with the damaged part of the rod 6. Since the seals slide, the range of scratches on the seal is narrowed, but the depth of the scratches becomes deeper, resulting in oil leakage. In particular, in the case of a structure in which the rod 6 is provided with a rack 7 that engages with the pinion 3 at the end of the rod 6, such as the hydraulic cylinder 5 of the power steering device described above, so that the rod 6 does not rotate under any conditions, the depth of the seal damage There is a problem in that the oil leakage becomes deeper and causes oil leakage, which seriously impedes the power steering system. Therefore, the purpose of this invention is to create a seal structure that uses internal pressure to rotate the sole so that even if there is a scratch on the rod, the depth of the scratch on the seal becomes shallow, thereby preventing oil leakage. Our goal is to provide the following.

[Means to solve the problem]

In order to achieve the above object, the seal structure of the present invention consists of a main body part and an annular part continuous to one side of the main body part,
a cover having an elongated annular portion inclined with respect to the axial direction and open at an end face; a rod slidably fitted into the main body portion of the cover; and a rod fitted into the annular portion of the cover;
and a seal holder that is reciprocatably penetrated by the rod, a pin fixed to the seal holder and movably engaged with the elongated hole, and the seal held by the holder,
a seal for sealing between the rod and the inner peripheral surface of the seal holder; a seal for sealing between the annular part of the cover and the outer peripheral surface of the seal holder; The present invention is characterized by comprising a biasing member interposed between the seal holder and a biasing member that biases the seal holder in a direction away from the main body. Further, it is preferable that the biasing member is an elastic ball, and the elastic balls are held at predetermined intervals in the circumferential direction by a retaining ring.

[Effect]

When the fluid pressure that presses the seal holder becomes stronger, the seal holder is moved backward while compressing the biasing member due to the fluid pressure, and is also rotated by the engagement of the pin with the elongated portion that is inclined with respect to the axial direction. On the other hand, when the fluid pressure pressing the seal holder becomes weaker, the seal holder is moved forward by the urging force of the urging member and rotated by the engagement between the elongate part and the pin. Therefore, the seal held in the seal holder reciprocates a minute distance while rotating, so even if there is a scratch on the rod, the scratch will spread over a wide area without contacting only one spot on the seal. Contact. Therefore, the scratches on the seal become wider but shallower, and shallow scratches can be covered by the elasticity of the seal, preventing oil leakage. Since the elongated hole is open at the end surface, the pin is fitted into the elongated hole simply by positioning the pin at the elongated opening end and fitting the annular portion of the cover into the seal holder from the axial direction. Therefore, the cover and the seal holder can be easily assembled. When the biasing member is composed of elastic balls such as rubber balls, and the elastic balls are held at predetermined intervals in the circumferential direction by a retaining ring, as the seal holder rotates,
The elastic ball that is in contact with the main body of the cover revolves while rotating. The retaining ring also rotates with the elastic ball. In this way, since the elastic ball rotates in conjunction with the seal holder, no twisting force is applied to the elastic ball, increasing the durability of the elastic ball. In addition, since the elastic balls are held at regular intervals in the circumferential direction by a retaining ring,
The seal holder can be pressed evenly.

【Example】

Hereinafter, the present invention will be explained in detail with reference to illustrated embodiments. FIG. 1 is a sectional view showing a part of a hydraulic cylinder of a power steering device. In the figure, 21 is a tube, and 22 is a cover fixed to the tube 21 with a key (not shown). The cover 22 includes a main body portion 23 and an annular portion 24 extending inward from the main body portion 23. An O-ring 26 provided on the outer periphery of the main body 23 seals between the main body 23 and the tube 21. As shown in FIGS. 1 and 2, the annular portion 24 of the cover 22 is provided with a long hole 27 that is inclined at 45 degrees with respect to the axial direction and is open at the end surface, and a through hole is provided in the center of the main body portion 23. There are 28. A rod 31 is slidably fitted into the through hole 28, and a tube 21 is fitted in the center of the rod 31.
A piston 32 that slides therein is connected to the rod 31, and a rack 33 that meshes with a pinion fixed to a steering shaft (not shown) is formed at the tip of the rod 31. A substantially cylindrical seal holder 35 is slidably fitted into the annular portion 24 of the cover 22. A rod 31 passes through a small diameter through hole 36 at the center of the seal holder 35 . In addition, the seal holder 35
A seal 38 is fixed inside the large diameter hole 37, and the seal 38 provides sole between the outer circumferential surface of the rod 31 and the inner circumferential surface of the seal holder 35. Further, a pin 41 is fixed to the outer periphery of the seal holder 35 so as to be movably engaged with the elongated hole 27 of the cover 22. Above pin 4
An O-ring 43 is attached to the outer periphery of the seal holder 35 so as to be located to the right in FIG. is sealed. Furthermore, a rubber ball 4, which is an example of an elastic ball as a biasing member, is provided between the inner end of the main body 23 of the cover 22 and the end of the seal holder 35.
4 are arranged at equal intervals circumferentially, and the seal holder 35 is attached to the first
It is biased to the left in the figure. The above seal structure operates as follows. Now, in the state shown in FIG. 1, if pressure oil is supplied from a port (not shown) to the chamber A on the right side of the piston 32 and the piston 32 and rod 31 are moving to the left, then the pressure oil is supplied to the chamber A on the right side of the piston 32. Due to the pressure of the oil, the seal holder 35 moves to the right in FIG. 1, that is, it moves backward while compressing the rubber ball 44. At this time, the seal holder 35 is rotated by the engagement between the pin 41 and the elongated hole 27. On the other hand, when pressure oil is supplied to chamber B on the left side of piston 32 and piston 32 and rod 31 move to the right, the pressure in chamber A is low, so seal holder 35
is moved to the left by the elastic force of the rubber ball 44, that is, moved forward, and rotated by the engagement between the elongated hole 27 and the pin 4I. Therefore, seal 38
The rod 38 rotates while reciprocating, and even if there is a scratch on the outer periphery of the rod 31, the scratch on the seal 38 will not become narrow or deep. That is, seal 3
Although the rotation of the seal 8 causes scratches over a wide range, the depth of the scratches becomes shallower, so that oil leakage from the seal 38 can be prevented. Note that since the O-ring 43 also reciprocates while rotating, durability is improved. Further, the elongated hole 2 provided in the annular portion 24 of the cover 22
7 is open at the end face of the annular portion 24, so the pin 4■ fixed to the seal holder 35 is positioned at the open end of the elongated hole 27, the cover 22 is fitted onto the seal holder 35, and the cover 22 is inserted into the seal holder 35 in the axial direction. The seal holder 35 can be assembled to the cover 22 by simply pushing the pin 41 into the elongated hole 27. In the above embodiment, the location where the elongated hole 27 and pin 41 are provided is O.
Since it is on the left side of the ring 43, that is, the side to which oil is supplied, oil is always supplied to the engagement portion between the elongated hole 27 and the pin 47, and the bottle 4 can be smoothly moved relative to the elongated hole 27. I can do it. Further, since the above embodiment is applied to a hydraulic cylinder of a power steering device, even if the rod 31 has the rack 33 at the tip and cannot rotate at all, the durability of the seal 38 can be increased by rotating the seal 38. Therefore, the reliability of the power steering device can be improved. Further, in the above embodiment, the rubber ball 44 is used as a biasing member.
This makes the structure simple and compact. Even if a disc spring is used in place of the rubber ball, a compact structure can still be achieved. If it is desired to increase the moving distance, a coil spring may be used as the biasing member. Figure 3.4 shows a second embodiment. The cover 52 consists of a main body portion 53 and an annular portion 54, and the annular portion 54 is provided with two elongated holes 57 that are inclined at 45 degrees with respect to the axial direction and open at the end surface of the annular portion 54. A seal holder 65 is slidably fitted into the annular portion 54 of the cover 52. Fixed to the seal holder 65 are pins 71 and 71 movably engaged with the elongated portions 57 and 57, respectively. A seal 68 is fixed to the inner circumferential surface of the seal holder 65, and the seal 68 seals between the inner circumferential surface of the seal holder 65 and the outer circumferential surface of the rod 31. Also, pin 7
1. There is a seal 73 on the right side of the elongated hole 57 in Figure 3.
is provided to seal between the inner peripheral surface of the annular member 54 and the outer peripheral surface of the seal holder 65. The above seal holder 65
A rubber ball 74 as an elastic ball is arranged between the end face of the cover 52 and the main body 53 of the cover 52. The rubber balls 74 are held at equal intervals around the circumference by a holding ring 75. This retaining ring 75 is disposed within a stepped portion 77 provided in the main body portion 53 of the cover 52, and its width is approximately half the diameter of the ball 74. In this structure as well, the seal holder 65 moves back and forth between the pin 71 and the elongated hole 55 while reciprocating from side to side due to the balance between the fluid pressure acting from the left side and the biasing force of the rubber ball 74.
The rotational movement is caused by the engagement with the seal 68, causing the seal 68 to perform the rotational movement while slightly reciprocating. therefore,
Even if there is a scratch on the rod 31, the scratch is on the seal 68.
There is no need to rub the seal 68, and the damage to the seal 68 is made shallow, thereby preventing oil leakage. Furthermore, since the elongated hole 57 is open at the end surface, the pin 71 can be easily inserted into the elongated hole 57 when assembling the seal holder 65 to the cover 52. In this embodiment, since the retaining ring 75 is disposed on the stepped portion 77, the rubber balls 74 can be easily retained at constant intervals. Furthermore, as the rubber ball 74 rotates and revolves together with the retaining ring 75 in conjunction with the rotation of the seal holder 65, there is no possibility that torsional force will be applied to the rubber ball 74 or that only one part will wear out. , the durability of the rubber ball 74 is increased. In addition, the retaining ring 75 is attached to a rubber ball 74.
are held at constant intervals in the circumferential direction, so that the seal holder 65 can be evenly pressed in the axial direction. Further, in the above embodiment, the cover and the tube are constructed as separate structures, but the cover and the tube may be constructed as an integral structure. In this case the tube becomes part of the cover. Further, in this specification, the term "long and large" is a concept that includes long grooves.

【Effect of the invention】

As is clear from the above, according to the present invention, the seal holder is reciprocated by the fluid pressure acting on the seal holder and the biasing force of the biasing member, and the seal holder is rotated by the engagement between the elongated part and the pin. The seal held in this seal holder is rotated while reciprocating with respect to the rod, so even if there is a scratch on the rod, the scratch will not rub only one place on the seal (therefore, The scratches on the seal will be shallower and oil leakage can be prevented.Also, since the elongated hole mentioned above is open at the end, position the pin at the open end of the elongated hole and insert the annular part of the cover into the seal holder. The pin fits into the elongated hole by simply fitting the seal holder in the axial direction, and the cover and seal holder can be easily assembled.Also, the biasing member may be composed of an elastic ball such as a rubber ball. When the above elastic balls are held at predetermined intervals in the circumferential direction by a retaining ring, as the seal holder rotates, the elastic balls that are in contact with the main body of the cover revolve while rotating, so that the elastic balls are twisted. No force is applied, increasing the durability of the elastic balls.Furthermore, since the elastic balls are held at constant intervals in the circumferential direction by the retaining ring, the seal holder can be pressed evenly.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a seal structure according to an embodiment of the present invention used in a hydraulic cylinder of a power steering device, Fig. 2 is a front view of a seal holder, and Fig. 3 is a sectional view of a seal structure according to a second embodiment. FIG. 4 is a perspective view of the retaining ring, and FIG. 5 is a schematic diagram of the power steering device. 22.52...Cover, 23.5'3...Body part,
24゜54...Annular part, 35.65...Seal holder, 27゜57...Long size, 41.71...Pin, 3
8.68...Seal, 26,43.73...0
Ring, 44.74...Rubber ball, 75...Retaining ring.

Claims (2)

[Claims] (1) A cover consisting of a main body and an annular part continuous to one side of the main body, the annular part having an elongated hole that is inclined with respect to the axial direction and opened at the end surface, and the main body of the cover. a rod that is slidably fitted into the cover, a seal holder that is fitted into the annular portion of the cover and reciprocatably penetrated through the rod, and a seal holder that is fixed to the seal holder and movable into the elongated hole. a pin to engage; a seal held by the seal holder to seal between the rod and the inner peripheral surface of the seal holder; and a seal to seal between the annular portion of the cover and the outer peripheral surface of the seal holder. , interposed between the main body of the cover and the seal holder,
A seal structure comprising: a biasing member that biases the seal holder in a direction away from the main body. (2) The seal structure according to claim 1, wherein the biasing member is an elastic ball, and the elastic ball is held at a predetermined interval in the circumferential direction by a retaining ring.