JP2010096205A - Shaft seal structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a shaft seal structure capable of securely preventing a sealed gas in a reservoir from leaking out of the space between the peripheral seal lip and an external cylinder by practically sufficiently securing sealing in the peripheral seal lip. <P>SOLUTION: The shaft seal structure includes a piston rod 3 reciprocally moving in a shaft direction, and an internal cylinder 2 and the external cylinder 5 provided on the same axis as that of the piston rod 3, and causes an annular support member 7 arranged between the piston rod 3 and the external cylinder 5 in a multiple cylinder shock absorber 1 sealed with a low pressure gas in the reservoir 6 partitioned with the internal cylinder 2 and the external cylinder 5 to closely bring an inner circumference seal lip 8 to be supported on the inner circumference side into contact with the piston rod 3 so as to be freely slid, and also to press an outer circumference seal lip 10 to be supported on the outer circumference side to the inner circumference face 5a of the external cylinder 5. In the shaft seal structure, the outer circumference seal lip 10 is arranged with an annular elastic member 11 capable of being elastically deformed in an outer circumference direction of the external cylinder 5 on the inner circumference side 10a and pushed to the inner circumference face 5a of the external cylinder 5 by utilizing elastic deformation of the elastic member 11. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a shaft seal structure that seals an annular space formed between a cylinder on the outer periphery of a shaft that reciprocally moves in the axial direction and an outer cylinder on the outer periphery of the cylinder, and is particularly mounted in a vehicle. In the multi-cylinder shock absorber, the outer peripheral side comes into contact with the inner peripheral surface of the outer cylinder while the inner peripheral side is in sliding contact with the outer peripheral surface of the piston rod, and the sealed gas or hydraulic oil leaks from the annular space to the outside. It is suitable for application to the structure of a shaft seal provided with a seal portion that prevents this.

  Conventionally, in a vehicle, a strut suspension device is mounted, and a strut mount composed of a rubber elastic body as a main element is interposed between the upper end of the strut having the shock absorber and the coil spring and the vehicle body. The vibration transmitted from the road through the tire is absorbed by the cooperative action of the shock absorber and the coil spring, and the vibration that cannot be absorbed by the shock absorber and the coil spring is absorbed by the strut mount. The vibration is prevented or suppressed from being transmitted to the body (see, for example, Patent Documents 1 to 5).

  Such shock absorbers, particularly double-tube shock absorbers, generally have the following structure. That is, the shock absorber is attached to the upper end portion of the inner cylinder (cylinder) so that the rod guide for guiding the piston rod is press-fitted or fitted to the outer periphery of the lower end portion of the ring-shaped rod guide. ing.

  A guide bush for smoothly guiding the piston rod in the thrust direction is provided on the inner periphery of the rod guide. Furthermore, the outer periphery of the upper end portion of the rod guide is fitted to the inner periphery of the upper end portion of an outer cylinder (outer shell) that covers the outer periphery of the cylinder.

  The rod guide is formed with an annular passage formed between the cylinder and the outer shell and enclosing the working oil (oil) and the low-pressure gas, that is, an oil passage as a passage means communicating with the reservoir.

  A support ring disposed coaxially with the piston rod is in contact with the upper portion of the rod guide, and an oil seal as an inner peripheral seal lip that is slidably contacted with the piston rod is provided on the inner peripheral side of the support ring. It is mated. At this time, a gap is formed between the oil seal and the upper surface of the rod guide.

  Here, the oil seal has a structure integrally having a dust lip on the upper side and an oil lip on the lower side of the piston rod. As a result, oil attached to the outer periphery of the piston rod with the oil lip is prevented from leaking to the outside, and dust and muddy water are prevented from entering the piston rod from the outside with the dust lip. Yes.

  Further, the outer periphery of the support ring in the oil seal is fitted into the outer shell so as to press against the inner peripheral surface of the outer shell, and is formed above the outer periphery of the support ring, outer shell, and rod guide. An outer peripheral seal lip (filled gas lip) is interposed between the inclined portions in a compressed state.

  Therefore, the sealed gas lip is pressed against the inner peripheral surface of the outer shell by the inclined portion of the rod guide, and the surface pressure generated by being urged to the inner peripheral surface of the outer shell by a repulsive force due to contraction of its own volume. Thus, the sealing performance is ensured to prevent the low-pressure gas or oil sealed in the reservoir from leaking outward from the oil seal, that is, above the oil seal.

  Further, the oil seal is fitted and held in the outer shell together with the rod guide by caulking the upper end of the outer shell on the upper surface of the outer peripheral portion thereof.

  In the shock absorber having such a configuration, when the piston rod is guided by the rod guide and enters and exits the cylinder, the oil in the cylinder is guided into the gap above the rod guide through the gap between the rod guide and the piston rod. It will be.

The oil guided into the gap is sent into the reservoir through the oil passage as the pressure in the gap increases. At this time, the oil flowing from the gap to the reservoir Since the outer periphery and the inner periphery of the outer shell are in close fitting contact with each other, they do not flow into the sealed gas lip side.
JP 2002-295678 A JP 2001-330074 A JP-A-2005-24099 JP 2006-266290 A JP 2004-251415 A

  However, such shock absorbers prevent leakage of low-pressure gas or oil sealed in the reservoir by the surface pressure generated when the sealed gas lip is urged to the inner peripheral surface of the outer shell. There is a concern that the magnitude of the surface pressure at this time may greatly vary in the dimensional accuracy of the outer shape of the rod guide and the shape of the inner peripheral surface of the outer shell.

  Moreover, since the upper end of the outer shell is sealed by caulking, the surface pressure of the sealed gas lip against the inner peripheral surface of the outer shell is caused by distortion in the shape of the inner peripheral surface of the outer shell during caulking. There is no denying the risk of a decline.

  In addition, it is conceivable to increase the tightening margin of the sealed gas lip and increase the surface pressure against the inner peripheral surface of the outer shell. It is difficult to prevent a decrease in sealing performance due to a decrease in surface pressure.

  As known to those skilled in the art, if the leakage of low-pressure gas occurs due to such deterioration in sealing performance, abnormal noise will be generated or it will be difficult to exert sufficient damping force, reducing the impact from the road surface. This can cause chronic problems such as dysfunction.

  Therefore, the present invention has been made in view of such a problem, and by sealing the outer peripheral seal lip and the outer cylinder between the outer peripheral seal lip and the outer cylinder, the sealing in the outer peripheral seal lip is ensured practically sufficiently. The main object is to provide a shaft seal structure that can reliably prevent gas from leaking out.

  An aspect of the present invention for achieving the above object includes a piston rod that reciprocates in the axial direction, an inner cylinder that is provided coaxially with the piston rod, and an outer cylinder. An annular support member disposed between the piston rod and the outer cylinder in a multi-cylinder shock absorber in which low-pressure gas is sealed in a partitioned reservoir has an inner peripheral seal lip supported on the inner peripheral side. A shaft seal structure in which the outer peripheral seal lip supported on the outer peripheral side is pressed against the inner peripheral surface of the outer cylinder while being slidably brought into close contact with the piston rod. An annular elastic member that can be elastically deformed toward the outer peripheral direction of the cylinder is disposed, and is urged toward the inner peripheral surface of the outer cylinder using the elastic deformation of the elastic member.

  Therefore, according to one aspect of the present invention, the elastic force of the elastic member provided on the outer peripheral seal lip acts on the outer peripheral side of the outer cylinder, thereby ensuring the lip surface pressure between the outer peripheral seal lip and the outer peripheral surface of the outer cylinder. As a result, it is possible to reliably prevent deterioration of the sealing performance over time. For this reason, it is possible to reliably prevent the sealed gas in the reservoir from leaking between the outer peripheral seal lip and the outer cylinder.

  In one aspect of the present invention, the elastic member is preferably an annularly connected coil spring, and in another aspect of the present invention, the elastic member has a horizontal cross section with respect to the axial direction. A spring material having a C-shaped cylindrical shape is preferable. Thereby, in any case, it is possible to press the outer peripheral seal lip against the inner peripheral surface of the outer cylinder, and to ensure a surface pressure between the outer peripheral seal lip and the outer peripheral surface of the outer cylinder, thereby reducing the sealing performance. Can be prevented.

  Moreover, in one aspect of the present invention, a ring member for preventing the coil spring from deforming toward the inner peripheral side of the outer peripheral seal lip is provided on the inner peripheral side of the outer peripheral seal lip. As a result, it is possible to prevent the coil spring from being deformed toward the inner peripheral side and falling off from the outer peripheral seal lip while being used.

  According to the present invention, the elastic force of the elastic member provided on the outer peripheral seal lip acts on the outer peripheral side of the outer cylinder, thereby ensuring the lip surface pressure between the outer peripheral seal lip and the outer peripheral surface of the outer cylinder, Aging deterioration can be surely prevented. Thus, it is possible to provide a shaft seal structure that can reliably prevent leakage of the sealed gas in the reservoir from between the outer peripheral seal lip and the outer cylinder.

  Hereinafter, the best mode for carrying out the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a schematic configuration diagram partially showing a cross section of an embodiment of a multi-cylinder shock absorber to which a shaft seal structure according to the present invention is applied, and FIG. 2 is an enlarged view of an oil seal portion in FIG. It is sectional drawing.

  In this shock absorber 1, the rod guide 4 for guiding the piston rod 3 is press-fitted or fitted to the outer periphery of the lower end portion of the ring-shaped rod guide 4 at the upper end portion of the cylinder 2 that is an inner cylinder. It is attached.

  A guide bush 4a that smoothly guides the piston rod 3 in the thrust direction is provided on the inner periphery of the rod guide 4. Further, the outer periphery of the upper end portion of the rod guide 4 is fitted to an inner peripheral surface 5 a of the upper end portion of the outer shell 5 as an outer cylinder covering the outer periphery of the cylinder 2.

  Also, the rod guide 4 is formed with an annular space formed between the cylinder 2 and the outer shell 5 and filled with hydraulic oil (oil) and low-pressure gas, that is, an oil passage 4 b as a passage means communicating with the reservoir 6. Yes.

  A support ring 7 as a support member disposed coaxially with the piston rod 3 is brought into contact with the upper portion of the rod guide 4, and is slidably contacted with the piston rod 3 on the inner peripheral side of the support ring 7. An oil seal 8 as an inner peripheral seal lip is fitted. At this time, a gap 9 is formed between the oil seal 8 and the upper surface of the rod guide 4.

  Furthermore, the support ring 7 is fitted and held in the outer shell 5 together with the rod guide 4 by caulking the upper end of the outer shell 5 on the upper surface of the outer peripheral portion thereof.

  Here, the oil seal 8 has a structure integrally including a dust lip 8 a on the upper side and an oil lip 8 b on the lower side of the piston rod 3. Thereby, oil attached to the outer periphery of the piston rod 3 is prevented from leaking to the outside by the oil lip 8b, and dust or muddy water is prevented from entering the piston rod 3 from the outside by the dust lip 8a. It is like that.

  Further, the outer periphery of the support ring 7 in the oil seal 8 is fitted into the outer shell 5 so as to be pressed against the inner peripheral surface 5 a of the outer shell 5, and the support ring 7, the outer shell 5, and the rod guide 4. A sealed gas lip 10 as an outer peripheral seal lip is provided between the inclined portions 4c formed on the upper periphery side of the outer peripheral side.

  In the case of the present embodiment, the sealed gas lip 10 is provided on the inner peripheral side 10a, unlike the conventional structure in which the inclined portion 4c of the rod guide 4 is pressed against the inner peripheral surface 5a of the outer shell 5. A coil spring 11 as an annular elastic member that can be elastically deformed toward the outer peripheral direction of the outer shell 5 is disposed in the recessed portion 10b, and the inner peripheral surface of the outer shell 5 is utilized by using the elastic deformation of the coil spring 11. It is energized to 5a.

  Thereby, the elastic force of the coil spring 11 provided on the sealed gas lip 10 acts on the outer peripheral side of the outer shell 5, thereby reducing the lip surface pressure between the sealed gas lip 10 and the inner peripheral surface 5 a of the outer shell 5. Optimum is ensured and the aging of the sealing performance of the lip surface can be surely prevented. Accordingly, it is possible to reliably prevent the sealed gas in the reservoir 6 from leaking between the sealed gas lip 10 and the outer shell 5.

  As described above, according to the shaft seal structure of this embodiment, the elastic force of the coil spring 11 provided on the sealed gas lip 10 acts on the outer peripheral side of the outer shell 5, whereby the sealed gas lip 10. And a lip surface pressure between the outer shell 5 and the inner peripheral surface 5a of the outer shell 5 can be ensured, and the aging of the sealing performance can be surely prevented. For this reason, it is possible to reliably prevent leakage of the sealed gas in the reservoir 6 from between the sealed gas lip 10 and the outer shell 5.

[Other Examples]
The best mode for carrying out the present invention has been described above with reference to the embodiments. However, the present invention is not limited to these embodiments, and various modifications can be made without departing from the scope of the present invention. And substitutions can be added.

  For example, in the shaft seal structure of the present invention, as shown in FIG. 3 (a) in which the same reference numerals are assigned to the portions corresponding to FIG. A backup ring 12 that is a ring member as shown in FIG. 3B for preventing the coil spring 11 from being deformed to the inner peripheral side of the sealed gas lip 10 may be provided on the peripheral side. . In this case, it is possible to obtain an advantage that the coil spring 11 can be prevented from being deformed toward the inner periphery 10a side of the sealed gas lip 10 and falling off from the recess 10b in advance. .

  Further, in the above-described embodiment, the case where the coil spring 11 connected in an annular shape is applied as the elastic member has been described. However, the present invention is not limited to this, and the above-described embodiment shown in FIG. The backup ring 12 made of a circular spring as a spring material having the same shape as the backup ring 12, that is, a cylindrical shape having a C-shaped horizontal cross section with respect to the axial direction of the piston rod 3 may be used. In short, any other elastic member may be used as the elastic member as long as it is urged toward the outer peripheral direction of the outer shell 5 so as to press the sealed gas lip 10 against the inner peripheral surface 5a of the outer shell 5. Can be widely applied.

  The present invention can be used in the automobile manufacturing industry, the automobile parts manufacturing industry, and the like.

It is a schematic block diagram which shows partially the cross section of the double cylinder type shock absorber in one Example to which the shaft seal structure of this invention is applied. (A) It is sectional drawing which expands and shows the oil seal part in FIG. 1, (b) It is a perspective view which expands and shows an elastic member. (A) It is sectional drawing which expands and shows the oil seal part of the double cylinder type shock absorber in the other Example to which the shaft seal structure of this invention is applied, (b) It is a perspective view which expands and shows an elastic member.

Explanation of symbols

1 ... Multi-cylinder shock absorber 2 ... Cylinder (inner cylinder)
3 ... Piston rod (shaft)
4 ... Rod guide 5 ... Outer shell (outer cylinder)
5a ... inner peripheral surface 6 ... reservoir 7 ... support ring (support member)
8 ... Oil seal (inner seal lip)
8a ... Oil lip 10 ... Sealed gas lip (peripheral seal lip)
11 ... Coil spring (elastic member)
12 ... Backup ring (elastic member)

Claims (4)

A multi-cylinder comprising a piston rod that reciprocates in the axial direction, an inner cylinder provided coaxially with the piston rod, and an outer cylinder, and low pressure gas sealed in a reservoir defined by the inner cylinder and the outer cylinder An annular support member disposed between the piston rod and the outer cylinder of the type shock absorber slidably contacts an inner peripheral seal lip supported on the inner peripheral side with the piston rod, and on the outer peripheral side. A shaft seal structure for pressing an outer peripheral seal lip supported on the inner peripheral surface of the outer cylinder,
An annular elastic member that is elastically deformable toward the outer peripheral direction of the outer cylinder is disposed on the inner peripheral side of the outer peripheral seal lip, and the inner peripheral surface of the outer cylinder is utilized using the elastic deformation of the elastic member. The shaft seal structure is characterized by being energized. The shaft seal structure according to claim 1, wherein the elastic member is a coil spring connected in an annular shape. The shaft seal structure according to claim 1, wherein the elastic member is a spring material having a C-shaped columnar cross section in the horizontal direction with respect to the axial direction. The ring member for preventing that the said coil spring deform | transforms into the inner peripheral side of the said outer periphery seal lip is provided in the inner peripheral side rather than the said coil spring in the said outer periphery seal lip. Shaft seal structure.

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