JP2012167698A - Shaft seal - Google Patents

Abstract

A shaft seal including a dust strip having excellent dust resistance is provided.
A shaft seal includes a reinforcing ring and a seal portion. The seal portion 220 includes an oil lip 230 and a dust lip 240. The dust lip 240 has a configuration in which a tip protrudes toward the outer peripheral surface of the shaft, and suppresses intrusion of dust from the atmosphere. In the dust lip 240, the reinforcement 300 having a rigidity lower than that of the reinforcement ring 210 is included, so that deterioration of the dust lip 240 with time is suppressed. Therefore, a reduction in dust resistance of the dust strip 240 can be suppressed.
[Selection] Figure 3

Description

  The present invention relates to a shaft seal comprising a dust strip.

  A shock absorber that attenuates the vertical vibration of the vehicle is filled with highly viscous oil for absorbing the vibration. The shaft seal that seals oil by moving in contact with the outer peripheral surface of the shaft is composed of an oil lip that suppresses oil leakage from the cylinder and a dust lip that suppresses dust intrusion from the atmosphere. . In order to improve dust resistance of a dust lip, a technique is disclosed in which a dust discharge path is provided for discharging dust radially outward along the atmosphere side surface of the dust lip. (For example, see Patent Document 1.)

JP-A-7-269712

  However, the dust lip is in contact with the shaft in a state of moving relative to the shaft, and deteriorates due to movement. As a result, the dusting force of the dust strip and the tightening allowance are lowered, and there is a risk that the dust resistance is lowered.

  The present invention has been made in view of the above problems, and one of its purposes is to provide a shaft seal including a dust strip excellent in dust resistance.

  In order to solve the above-mentioned problems, a shaft seal according to the present invention has a tip projecting toward the outer peripheral surface of the shaft, and is positioned on the outer side in the radial direction of the shaft with respect to the annular dust strip centering on the shaft. And an annular reinforcing ring centered on the shaft, and a reinforcing material having a rigidity lower than that of the reinforcing ring inherent in the dust lip.

  According to the present invention, it is possible to suppress a decrease in dust resistance by incorporating a reinforcing material in the dust lip.

It is a whole sectional view showing an example of composition of a shock absorber. It is a fragmentary sectional view showing an example of composition of a shock absorber. It is sectional drawing which shows the shaft seal concerning embodiment of this invention. It is a side view which shows the reinforcing material inherent in the dust lip concerning embodiment of this invention. It is a top view which shows the reinforcing material inherent in the dust lip concerning embodiment of this invention. It is a figure which shows the dust strip before deterioration with time. It is a figure which shows the dust strip after deterioration with time.

  Hereinafter, a shaft seal according to an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is an overall cross-sectional view showing an example of the configuration of a shock absorber. The shock absorber 100 is one device that constitutes the suspension of an automobile. The shock absorber 100 has a function of relaxing and converging the periodic vibration due to the characteristics of the spring in a system that absorbs vibration and shock by the spring.

  The shock absorber 100 includes a cylinder 110, a piston portion 120, a piston rod 130, a rod side oil chamber 140, a piston side oil chamber 150, an outer cylinder 160, a reservoir 170, a base valve 180, a cylinder head 190, and a shaft seal 200. . In the shock absorber 100, a piston rod 130 is movably inserted through a piston portion 120 provided with a damping force generation mechanism in a cylinder 110. The piston part 120 divides the rod side oil chamber 140 and the piston side oil chamber 150 in the cylinder 110.

  The outer cylinder 160 is coaxially disposed outside the cylinder 110, and a reservoir 170 including an oil chamber and a gas chamber is defined between the cylinder 110 and the outer cylinder 160. The reservoir 170 communicates with the piston-side oil chamber 150 through the base valve 180. The cylinder head 190 is attached to the upper end portion of the cylinder 110. The shaft seal 200 is attached to the outer peripheral surface of the cylinder head 190 at the upper end portion of the outer cylinder 160.

  FIG. 2 is a partial cross-sectional view showing an example of the configuration of the shock absorber 100 around the shaft seal 200. The shaft seal 200 includes, for example, a reinforcing ring 210 and a seal portion 220. The shaft seal 200 is provided coaxially with the piston rod 130 and seals the gap between the piston rod 130 and the outer cylinder 160 that reciprocally move relative to each other.

  The seal portion 220 has an annular shape, and the inner peripheral surface contacts the outer peripheral surface of the piston rod 130 in a moving state, and the outer peripheral surface is attached to the inside by the reinforcing ring 210. The seal part 220 is connected to the outer cylinder 200 via the reinforcing ring 210.

  The reinforcing ring 210 is provided to bring the seal portion 220 into contact with the piston rod 130 in a moving state, and a material having high rigidity is used.

  FIG. 3 is a sectional view showing a shaft seal 200 according to the embodiment of the present invention. The seal portion 220 is composed of an oil lip 230 that suppresses oil leakage from the cylinder and a dust lip 240 that suppresses intrusion of dust from the atmosphere while in contact with the outer peripheral surface of the piston rod 130. . The oil lip 230 and the dust lip 240 are integrally formed of rubber such as nitrile rubber (NBR) or fluorine rubber (FKM), and are installed coaxially with the piston rod 130.

  The oil lip 230 scrapes back the oil adhering to the outer peripheral surface of the piston rod 130 to the inside, and returns it to the reservoir 170 installed in the housing. On the inner peripheral surface of the oil lip 230, a main oil lip 230a and a sub oil lip 230b project from the cylinder in order to suppress oil leakage.

  The main oil lip 230a and the sub oil lip 230b are annular members extending toward the outer peripheral surface of the piston rod 130, and the cross sections of the main oil lip 230a and the sub oil lip 230b are triangular. The minimum inner diameter of the main oil lip 230 a and the sub oil lip 230 b is formed to be slightly smaller than the outer dimension of the piston rod 130. The main oil lip 230a and the sub oil lip 230b are in contact with the outer peripheral surface of the piston rod 130 while moving in a liquid-tight manner.

  The main oil lip 230a may be dragged and deformed by the piston rod 130 in accordance with the relative reciprocation of the piston rod 130 and the housing. When this deformation is repeated, the sealing performance of the main oil lip 230a is impaired. Therefore, in order to suppress deformation of the main oil lip 230a, the sub oil lip 230b is installed above (atmosphere side) when viewed from the side of the main oil lip 230a. The inner diameter dimension of the seal portion 220 at the distal end portion of the sub oil lip 230b is slightly larger than the inner diameter dimension of the seal portion 220 at the distal end portion of the main oil lip 230a.

  A spring ring 250 is attached to the outer peripheral surface of the oil lip 230 at a position corresponding to the main oil lip 230a. The spring ring 250 is a garter spring, for example, and may be attached to the dust lip 240. The spring ring 250 urges the tip end of the main oil lip 230a toward the outer peripheral surface of the piston rod 130 by a radial force. The tightening force is a radial force that tightens the shaft seal 200 (that is, the oil lip 230 and the dust lip 240) to the piston rod 130. Thereby, the adhesiveness of the oil lip 230 and the piston rod 130 can be improved. And by improving the liquid tightness of the shaft seal 200, the oil lip 230 can suppress oil leakage from the cylinder.

  The dust lip 240 is disposed above (atmosphere side) when viewed from the side of the oil lip 230. On the inner peripheral surface of the dust lip 240, a main dust lip 240a and a secondary dust lip 240b project from the atmosphere in order to suppress intrusion of dust from the atmosphere.

  The main dust strip 240a and the sub dust strip 240b are annular members extending toward the outer peripheral surface of the piston rod 130, and the cross sections of the main dust strip 240a and the sub dust strip 240b are triangular. The minimum inner diameter dimension of the main dust strip 240a and the auxiliary dust strip 240b is formed to be slightly smaller than the outer dimension of the piston rod 130. The main dust strip 240a and the secondary dust strip 240b are brought into contact with the outer peripheral surface of the piston rod 130 in a state of moving relative to each other by an annular reinforcing ring located radially outside the shaft.

  The main dust strip 240a has a configuration that protrudes obliquely upward when viewed from the radial inner side and side surface of the piston rod 130 and becomes thinner as viewed from the cross section. That is, the main dust strip 240a has a structure that becomes thinner as it goes upward when viewed from the side surface along the axial direction of the piston rod 130 and approaches the outer peripheral surface of the piston rod 130. That is, the main dust strip 240a is of a so-called scraper type. Accordingly, when viewed in cross section, the tip end side of the main dust strip 240 a can follow the piston rod 130. Further, the secondary dust strip 240b is installed on the cylinder side of the main dust strip 240a so that a large load is not applied to the main dust strip 240a. The inner diameter dimension of the seal portion 220 at the distal end portion of the sub dust strip 240b is slightly larger than the inner diameter dimension of the seal portion 220 at the distal end portion of the main oil lip 230a.

  As shown in FIG. 3, the main dust strip 240a has a reinforcing member 300 extending from the reinforcing ring 210 toward the tip of the main dust strip 240a. The reinforcing member 300 is a material having lower rigidity than the reinforcing ring 210, and for example, spring steel or resin is appropriate. However, unlike the reinforcing ring 210, the reinforcing member 300 requires appropriate elasticity. That is, the reinforcing member 300 is required to improve the elasticity of the main dust strip 240a.

  The reinforcing member 300 is shaped as shown in FIG. 4 when viewed from the side. Further, the reinforcing member 300 has a shape as shown in FIG. 5 when viewed from above. As shown in these drawings, the reinforcing member 300 includes an annular flat surface portion 300 a fixed to the reinforcing ring 210 and a spring portion 300 b protruding from the annular flat surface portion 300 a toward the piston rod 130. .

  The flat surface portion 300a is fixed to the reinforcing ring 210 by welding or the like, and is then vulcanized and molded with rubber forming the seal portion 220. Thus, the seal portion 220 does not need to fix the reinforcing ring 210 and the reinforcing material 300, and can be easily formed. In addition, since the reinforcing ring 210 and the reinforcing material 300 are integrated in the seal portion 220, the rigidity can be improved.

  The spring portion 300b protrudes from the flat portion 300a toward the outer peripheral surface of the piston rod 130, and has a tapered triangle toward the tip. As shown in FIGS. 4 and 5, the reinforcing member 300 includes a flat portion 300 a and eight spring portions 300 b extending from the flat portion 300 a to the piston rod 130. However, the spring portion 300b only needs to be less rigid as it approaches the tip of the dust strip 240 from the reinforcing ring 210, and may be a single cylindrical member that is trapezoidal when viewed from the side.

  Since the reinforcing member 300 included in the dust lip 240 is composed of the flat surface portion 300a and the spring portion 300b, even if the tip of the dust lip 240 moves in contact with the piston rod 130 while moving, it prevents deterioration over time. Can do. Thus, dust resistance can be improved by minimizing the shape change of the dust lip 240.

  As shown in FIG. 6, the known dust lip 1240 is arranged so that the allowance between the dust lip 1240 and the piston rod is a predetermined amount (length indicated by an arrow A). However, the alternate long and short dash line in the figure indicates the outer peripheral surface of the piston rod as viewed from the side. The tightening allowance is the length of the portion where the piston rod and dust strip 1240 overlap in the radial direction when viewed from the side. As a result, by bringing the dust lip 1240 into contact with the piston rod in a moving state, it is possible to suppress the intrusion of dust into the cylinder due to the generation of a tightening force.

  However, as shown in FIG. 7, by using the shock absorber for a predetermined period, the dust lip 1240 deteriorates (deforms) over time from the initial shape (chain line) (solid line). As a result, the tightening margin of the dust strip 1240 is reduced from the predetermined amount (the length indicated by the arrow A) (the length indicated by the arrow B). Therefore, when the tightening margin is reduced, the tightening force may be reduced and the dust resistance may be reduced.

  On the other hand, the present invention can suppress the deterioration over time of the dust lip 240 by providing the reinforcing material 300 in the dust lip 240. As a result, it is possible to suppress a reduction in dust resistance of the dust strip 240.

  In addition, this invention is not limited to the said embodiment, A various modification can be employ | adopted within the scope of the present invention.

  For example, according to the above-described embodiment, the reinforcing member 300 includes the flat portion 300a and the spring portion 300b. However, the reinforcing member 300 may include only the spring portion 300b without the flat portion 300a. The spring portion 300b may be a spring ring 250, that is, a garter spring.

  Further, according to the above embodiment, the oil lip 230 and the dust lip 240 of the seal portion 220 are constituted by the main oil lip 230a and the auxiliary oil lip 230b, respectively, the main dust lip 240a and the auxiliary dust lip 240b. 230 and the dust lip 240 may be composed only of the main oil lip 230a and the main dust lip 240a, respectively.

  DESCRIPTION OF SYMBOLS 200 ... Shaft seal, 210 ... Reinforcement ring, 220 ... Seal part, 230 ... Oil seal, 230a ... Main oil seal, 230b ... Sub oil seal, 240 ... Dust seal, 240a ... Main dust seal, 240b ... Sub dust seal, 300 ... Reinforcing material , 300a ... plane part, 300b ... spring part

Claims (5)

An end of the shaft projects toward the outer peripheral surface of the shaft, and an annular dust strip centered on the shaft;
An annular reinforcing ring located on the outer side in the radial direction of the shaft from the dust lip and centered on the shaft;
A reinforcing material that is less rigid than the reinforcing ring inherent in the dust lip,
A shaft seal comprising: The shaft seal according to claim 1, wherein the reinforcing material is a reinforcing material extending from the reinforcing ring toward a tip of the dust lip. 3. The shaft seal according to claim 1, wherein the reinforcing member is a reinforcing member whose rigidity decreases as it approaches the tip of the dust strip from the reinforcing ring. 4. The shaft seal according to claim 1, wherein the reinforcing member is a spring ring. An annular first duster having a tip projecting toward the outer peripheral surface of the shaft and having the shaft as a center;
An annular second duster centered on the shaft, with a tip projecting toward the outer peripheral surface of the shaft, an inner diameter dimension at the distal end portion being smaller than an inner diameter dimension at the distal end portion of the first dust strip;
An annular reinforcing ring that is positioned radially outward of the shaft from the first dust strip and the second dust strip;
A reinforcing material that is less rigid than the reinforcing ring inherent in the first dust lip;
A shaft seal comprising:

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