SEALING ASSEMBLY

Abstract: A sealing assembly is adapted to be disposed between a stationary part (2) and a rotary shaft (1) in the stationary part so as to provide a seal in the gap between the stationary (2) part and the rotary shaft (1). The sealing assembly has a slinger (3) capable of rotating as a unit with the rotary shaft (1), and a rubber seal (5) having a lip (5a) which makes a sliding contact with the slinger (3). The portion of the slinger (3) contacted by the lip (5a) of the rubber seal (5) is provided with apertures (7) which allow a lubricating oil to flow into the region of the sliding contact between the lip (5a) of the seal rubber (5) and the portion of the slinger (3).

Description: The present invention relates to a sealing assembly and, more particularly, to a sealing assembly which suffers from reduced wear and which is capable of improving sealing effect. A sealing assembly is known which is fixed to a stationary part such that a rotary shaft rotatably extends through the sealing assembly, thereby providing a seal in the gap between the stationary part and the rotary shaft. Figs. 4 to 6 illustrate the construction of a typical example of the sealing assembly of the kind described. The sealing assembly shown in these Figures has a slinger 43 composed of a tubular portion 43b through which the rotary shaft 41 extends and a radial portion 43a provided on one axial end of the tubular portion 43b and extending radially outwardly therefrom, and a rubber seal 45 which is disposed on the outer side of the tubular portion 43b of the slinger 43. The rubber seal 45 has a reinforcement member 44 embedded therein. The reinforcement member has a substantially L-shaped cross-section with one leg 44a thereof being directed towards the slinger 43. The rubber seal 45 has outer peripheral surface fitting in the bore in the stationary part 42, and is provided, at its portion adjacent the slinger 43, with a lip 45a contacting the radial portion 43a of the slinger 43 and a lip 45b which is directed towards the tubular portion 43b on the rotary shaft 41. In order to impart a high oil-gathering effect produced by the lips 45a and 45b, a spiral groove 46 starting at the center and terminating at the peripheral end is formed in the surface of the radial portion 43a of the slinger 43 facing the lip 45a. In operation, the slinger 43 rotates together with the rotary shaft 41 as a unit therewith, with the lip 45a of the rubber seal 45 kept in sliding contact with the radial portion 43a of the slinger 43 thereby attaining a sealing effect. This known sealing assembly, however, suffers from the following disadvantages. In operation, the spiral groove 46 formed in the radial portion 43a of the slinger 43 serves to displace the oil radially outwardly during rotation of the slinger 43 as shown in Fig. 6, with the result that the lubricating condition on the sliding surface of the lip 45a is impaired to adversely affect the durability. In addition, since the pressure at which the lip 45a contacts with the slinger 43 is kept constant regardless of the rotation speed 41 of the rotary shaft 41, the resistance torque is undesirably increased as the rotation speed increases. International Patent Publication No. WO 85/03990 discloses a sealing assembly in which a rubber seal is mounted on a rotary shaft and has a lip for contacting a slinger mounted on a stationary surface. Apertures are provided through the lip to regenerate a lubricant film. However, there is a large risk in this arrangement that the oil passage apertures are closed as a result of thermal expansion. Moreover, oil is discharged into an air chamber after lubrication. This arrangement cannot therefore provide a satisfactory seal. The present invention aims to provide a sealing assembly in which the sliding frictional resistance between the lip and the slinger is reduced to suppress the wear of the lip. The present invention also aims to provide a sealing assembly which is improved to prevent resistance torque from increasing when the rotation speed is increased. To this end, according to the present invention, there is provided a sealing assembly for disposal between a stationary part and a rotary shaft which extends through said stationary part, so as to provide a seal for the gap between said stationary part and said rotary shaft, said sealing device comprising a slinger having a radial portion, and a rubber seal having a lip for sliding contact with said radial portion of said slinger, characterised in that said slinger is attached to said rotary shaft for rotation as a unit therewith, said radial portion extending in the directions perpendicular to the axis of rotation of said rotary shaft, and said rubber seal is secured to said stationary part, and in that said radial portion of said slinger, which is contacted by said lip of said rubber seal, is provided with oil passage apertures which allow a lubricating oil to flow into the region of the sliding contact, the surface of said radial portion contacted by said lip being provided with a spiral groove. Said rubber seal may be provided with a reduced-diameter peripheral surface at which said rubber seal is fitted in said stationary part. Said radial portion of said slinger may include a tab portion which is folded back from the radial end of said radial portion towards said rotary shaft and away from said lip. The lubricating oil supplied through the apertures well lubricates the sliding surfaces so that the undesirable increase in the resistance torque due to increase in the rotation speed is suppressed. Embodiments of the present invention will now be described by way of example only with reference to the accompanying drawings, in which:- Fig. 1 is a sectional view of a first embodiment of the sealing assembly in accordance with the present invention, taken at a plane which includes the axis of a rotary shaft on which the sealing assembly is set; Fig. 2 is a bottom plan view of a slinger incorporated in the sealing assembly of Fig. 1; Fig. 3 is a longitudinal sectional view of another embodiment of the sealing device in accordance with the present invention; Fig. 4 is a sectional view of a known sealing assembly; Fig. 5 is an end view of a slinger incorporated in the sealing assembly of Fig. 4; and Fig. 6 is an illustration of the relationship between the slinger and the rubber seal lip in she sealing assembly of Fig. 3. Figs. 1 and 2 show a first embodiment of the sealing assembly in accordance with the present invention. The sealing assembly is composed of a slinger 3 and a rubber seal 5. The slinger 3 has a tubular portion 3b through which a rotary shaft 1 extends, and a radial portion 3a provided on one end of the tubular portion 3b and extending radially outwardly therefrom. The rubber seal 5, which is secured to a stationary portion 2, is provided with a reinforcement member 4 embedded therein. The reinforcement member 4 has a substantially L-shaped cross-section with its one leg 4a directed towards the tubular member 14 of the slinger 3. The rubber seal 5 surrounds the tubular portion 3b of the slinger 3. The rubber seal 5 has a stepped outer peripheral surface the reduced-diameter portion 5d of which fits in the stationary part 2. The rubber seal 5 is provided at its portion adjacent to the slinger 3 with a lip 5a which resiliently contacts with radial portion 3a of the slinger 3 and also with a lip 5b which is directed towards the tubular portion 3a of the slinger 3. The surface of the radial portion 3a of the slinger 3 facing the lip 5a is provided with a spiral groove 6 which starts at the inner peripheral end and terminates in the outer peripheral end of the radial portion 3a. A plurality of apertures 7 are formed in an annular region of the radial portion 3a contacted by the lip 5a. In operation, the rotation of the rotary shaft 1 causes lubricating oil to be displaced radially outwardly in the sliding region between the lip 5a of the rubber seal 5 and the radial portion 3a of the slinger 3, by the effect of the spiral groove 6 formed in the radial portion 3a of the slinger 3. However, in the sealing assembly of the present invention, new lubricating oil is supplied into the sliding region through the apertures 7 formed in the radial portion 3a of the slinger 3. Thus, according to the invention, new portion of lubricating oil is supplied through the apertures 7 through the apertures 7 so as to compensate for radially outward displacement of the oil caused by the action of the groove 6 formed in the slinger, so that a good lubricating condition is maintained in the region of the sliding contact between the radial portion 3a of the slinger 3 and the lip 5a, whereby the wear-resistance characteristics of the sealing assembly is remarkably improved. This good lubricating condition obtained in the region of the sliding contact between the lip 5a of the rubber seal 5 and the radial portion 3a of the slinger 3 effectively suppresses substantial increase in the resistance torque even when the rotary shaft rotates at a high speed. In addition, since only the reduced-diameter portion 5d of the rubber seal 5 fits in the stationary part 2 while the large-diameter portion 5c contacts with a side surface of the stationary part 2, the rubber seal 5 is prevented from moving axially even when a force is generated in the axial direction of the rotary shaft 1, thus preventing undesirable axial shift of the sealing assembly. The provision of the step on the outer peripheral surface of the rubber seal 5 is not essential. Namely, the rubber seal 5 may have a straight outer peripheral surface, i.e., only the reduced-diameter portion 5d which fits in the stationary part 2. Fig. 3 shows another embodiment of the sealing assembly in accordance with the present invention. This embodiment has a slinger 33 and a rubber seal 35. The slinger 33 has a tubular portion 33b through which the rotary shaft 31 extends, a radial portion 33a provided on one end of the tubular portion 33b and extending radially outwardly therefrom, and a tab portion 33c inwardly bent from the radially outer end of the radial portion 33a. The rubber seal 35, which is secured to a stationary part 32, has a reinforcement member 34 embedded therein having an L=shaped cross-section, one leg of which is directed towards the slinger 33. The rubber seal 35 is disposed so as to surround the tubular portion 33b of the slinger 33. The rubber seal 35 is provided at its portion adjacent to the slinger 33 with a lip 35a contacting with the radial portion 33a of the slinger 33 and a lip 35b which is directed towards the tubular portion 33b of the slinger 33. Furthermore, as in the case of the preceding embodiment, the surface of the radial portion 33a of the slinger 33 facing the lip 35a of the rubber seal 35 is provided with a spiral groove which starts at the inner peripheral end and terminates in the outer peripheral end of the radial portion 33a and a plurality of apertures 37 are formed in the annular region of the radial portion 33a which contacts with the lip 35a. In operation of this sealing assembly, rotation of the rotary shaft 31 causes lubricating oil to be displaced radially outwardly along the radial portion 33a of the slinger 33. In order to compensate for the radially outward displacement of the lubricating oil, new portion of the lubricating oil is supplied to the sliding contact region between the lip 35a of the rubber seal 35 and the radial portion 33a of the slinger 33. In this embodiment, lubricating oil is accumulated and pooled in an annular recess which is formed by the radial portion 33a and the tab portion 33c which is folded back from the radial outer end extremity of the radial portion 33a. This oil is caused to flow through the apertures 37 as indicated by arrows so as to come into the region of the sliding contact between the lip 35a of the seal rubber 35 and the radial portion 33a of the slinger 33. By virtue of the continuous supply of the lubricating oil, a good lubricating condition is maintained in the region of the sliding contact between the lip 35a of the seal rubber 35 and the radial portion 33a of the slinger 33, so that the wear resistance can be remarkably improved. This good lubricating condition also suppresses any undesirable increase in the resistance torque which may otherwise be increased considerably when the speed of rotation of the rotary shaft 32 is increased. The rubber seal 35 may have a stepped outer peripheral surface such that only a reduced-diameter portion fits in the bore formed in the stationary part while a large-diameter portion rests on one side of the stationary member, so that any risk for the sealing assembly to undesirably move axially is prevented.

Claims: A sealing assembly for disposal between a stationary part (2;32) and a rotary shaft (1;31) which extends through said stationary part (2;32), so as to provide a seal for the gap between said stationary part (2;32) and said rotary shaft (1;31), said sealing device comprising a slinger (3;33) having a radial portion (3a;33a), and a rubber seal (5;35) having a lip (5a;35a) for sliding contact with said radial portion of said slinger, characterised in that said slinger (3;33) is attached to said rotary shaft (1;31) for rotation as a unit therewith, said radial portion (3a;33a) extending in the directions perpendicular to the axis of rotation of said rotary shaft (1;31) and said rubber seal (5;35) is secured to said stationary part, and in that said radial portion of said slinger, which is contacted by said lip of said rubber seal (5;35), is provided with oil passage apertures (7;37) which allow a lubricating oil to flow into the region of the sliding contact, the surface of said radial portion (3a;33a) contacted by said lip (5a;35a) being provided with a spiral groove (6). A sealing assembly according to claim 1, wherein said rubber seal (5) is provided with a reduced-diameter peripheral surface (5d) at which said rubber seal (5) is fitted in said stationary part (2). A sealing assembly according to Claim 1, wherein said radial portion (33a) of said slinger (33) includes a tab portion which is folded back from the radial end of said radial portion (33a) towards said rotary shaft (31) and away from said lip (35a).

Inventors: ANZUE, KAORU, ISOMOTO, JUN, TAKEI, NOBUO
Applicants: MITSUBISHI JIDOSHA KOGYO KABUSHIKI KAISHA, NOK CORPORATION
Application year: 1989
Main classification: F16J15
IPC codes: F16J15