JP2011117550A - Sealing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sealing device exerting favorable sealing performance over long periods by improving heat resistance and durability of a seal lip of an oil seal in a sealing device with a structure in which the oil seal is closely contacted and slid relative to a rotary shaft. <P>SOLUTION: The oil seal 1 is arranged between a housing 11 and the rotary shaft 21. The oil seal 1 includes the seal lip 4 arranged toward a sealed fluid side A and sealing a sealed fluid by closely contacting with the outer peripheral surface 21a of the rotary shaft 21 freely slidably. The rotary shaft 21 includes a spiral groove 22 at a part on an atmosphere side B relative to a sliding part with the seal lip 4 in the outer peripheral surface 21a. During rotation, the spiral groove 22 generates an air flow toward the seal lip 4, thereby cooling the seal lip 4 by the air flow, and applies pressure to the seal lip 4. Moreover, in the outer periphery of the spiral groove 22, a cylindrical guide 6 for narrowing the radial width of the flow passage of the air flow is arranged, and the cylindrical guide 6 is held by the oil seal 1. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a sealing device, and more particularly to a sealing device having a structure in which an oil seal slides in close contact with a rotating shaft. The sealing device of the present invention is used, for example, in the field related to automobiles or used in general general-purpose machines.

  Conventionally, as shown in FIG. 3, a seal lip 54 is fixed to the inner periphery of the shaft hole 51a of the housing 51 so as to seal between the housing 51 and the rotary shaft 52 inserted through the shaft hole 51a of the housing 51. A sealing device (oil seal) 53 having a structure slidably in close contact with the outer peripheral surface of 52 is widely known (see Patent Document 1).

  However, when this conventional sealing device 53 is used under poor lubrication conditions, high peripheral speed conditions, or conditions where the heat dissipation of the shaft is not good, such as a hollow shaft, the heat resistance of the seal lip 54 is insufficient and the seal There is a concern that cracks and the like occur on the sliding surface 54a of the lip 54, resulting in a decrease in sealing performance and leakage.

Japanese Patent Laid-Open No. 11-230363 (FIG. 4) JP-A-5-196147

  Further, the above-mentioned Patent Document 2 (Japanese Patent Laid-Open No. 5-196147) has a slinger in which the seal lip is slidably in close contact, and the slinger is provided with a spiral groove. A technique for improving the sealing performance by pushing back is described. However, this conventional sealing device is different from the present invention in that the spiral groove is provided at a position directly below the seal lip according to the difference in purpose from the present invention, and corresponds to the cylindrical guide of the present invention. The present invention is also different from the present invention in that it does not have the constituent elements.

  In view of the above, the present invention can improve the heat resistance and durability of the seal lip of the oil seal in a sealing device having a structure in which the oil seal slides in close contact with the rotating shaft. An object of the present invention is to provide a sealing device that can exhibit good sealing performance.

  To achieve the above object, a sealing device according to claim 1 of the present invention has an oil seal disposed between a housing and a rotating shaft, and the oil seal is disposed toward a sealing fluid side and rotates. A seal lip that is slidably in close contact with the outer peripheral surface of the shaft and seals the sealing fluid; and the rotating shaft has a spiral groove in a portion closer to the atmosphere than the sliding portion with the seal lip on the outer peripheral surface. The spiral groove, when rotating, generates an air flow toward the seal lip, cools the seal lip by the air flow and applies pressure to the seal lip, on the outer periphery of the spiral groove, A cylindrical guide for narrowing the radial width of the air flow channel is disposed, and the cylindrical guide is held by the oil seal.

  The sealing device according to a second aspect of the present invention is the sealing device according to the first aspect, wherein the cylindrical guide is a flange portion extending radially outward from one axial end of the cylindrical portion. The cylindrical portion is used as a guide portion for reducing the radial width of the flow path, and the flange portion is used as a held portion for being held by the oil seal. It is characterized by being.

  The sealing device according to a third aspect of the present invention is the sealing device according to the first or second aspect, wherein the cylindrical guide slides on the top of a screw thread whose inner peripheral surface forms the spiral groove. It is characterized by free contact.

  The sealing device according to a fourth aspect of the present invention is the sealing device according to the first or second aspect, wherein the cylindrical guide has a minute tip and a top of a screw thread whose inner peripheral surface forms the spiral groove. It is characterized by facing through a radial gap.

  In the sealing device having the above configuration, when the rotation shaft rotates, the spiral groove provided on the outer peripheral surface of the rotation shaft rotates, and an air flow is generated toward the seal lip by the rotation of the spiral groove. The air flow is blown onto the atmosphere side surface of the seal lip to cool the seal lip and suppress heat stored in the seal lip from sliding with the shaft. In addition, pressure is applied to the atmosphere side surface of the seal lip by the air flow to try to lift the seal lip from the rotating shaft, so that the pressing force on the shaft of the seal lip is reduced and sliding heat generation is reduced. Accordingly, since the seal lip is directly cooled and sliding heat generated in the seal lip is reduced, thermal deterioration and sliding wear of the seal lip are suppressed, and heat resistance and durability are improved. In the present invention, the rotating shaft includes components such as a slinger and a sleeve that are fixed to the rotating shaft and rotate together. In general, so-called outside air is used as the air.

  Since the air flow is generated by the pumping action by the spiral groove, it is desirable to make the flow path as narrow as possible in order to increase the flow rate or increase the flow velocity. Therefore, in the present invention, a cylindrical guide for narrowing the radial width of the airflow passage is arranged on the outer periphery of the spiral groove, thereby narrowing the passage. The cylindrical guide is held by an oil seal.

  As a preferable example of the cylindrical guide, an annular part having a substantially L-shaped cross section in which a flange portion is integrally formed from one end in the axial direction of the cylindrical portion outward in the radial direction. Of these, the cylindrical portion is a guide portion arranged on the outer periphery of the spiral groove to narrow the radial width of the flow path, and the flange portion is a held portion that is assembled to the oil seal to be held by the oil seal. The

  In order to narrow the flow path, it is preferable that the inner peripheral surface of the cylindrical guide is slidably brought into contact with the top of the screw thread forming the spiral groove. When there is a concern about the increase or the occurrence of sliding contact noise, the inner peripheral surface of the cylindrical guide is opposed to the top of the screw thread forming the spiral groove through a minute radial gap.

  In the present invention, since the spiral groove generates an air flow toward the seal lip, the spiral groove is provided on a portion closer to the atmosphere than the sliding portion with the seal lip on the outer peripheral surface of the rotating shaft. It is provided only on the side part. That is, the spiral groove is not provided in the sliding portion with the seal lip. In this respect, the present invention provides the spiral groove in the sliding portion with the seal lip and pushes back the sealing fluid by its pumping action. This is different from the prior art described in Patent Document 2. In the present invention, since the seal lip contacts the cylindrical surface of the rotating shaft not provided with the spiral groove, so-called stationary leakage (seal fluid leaks through the spiral groove when the rotating shaft is stopped) is effectively suppressed. It will be.

  The present invention has the following effects.

  That is, in the sealing device of the present invention having the above-described configuration, an air flow is generated toward the seal lip by rotating the spiral groove when the rotary shaft rotates, and this air flow is blown to the seal lip. As the lip cools, pressure acts on the seal lip to reduce the tension of the seal lip. Since the cylindrical guide for narrowing the radial width of the air flow channel is arranged on the outer periphery of the spiral groove, the air flow is blown to the oil seal in a state where the flow rate and flow velocity are large. Therefore, thermal deterioration and sliding wear of the seal lip can be suppressed, and its heat resistance and durability can be improved. Further, since the spiral groove is provided only on a part of the outer peripheral surface of the rotating shaft, so-called stationary leakage can be suppressed by the seal lip. Therefore, according to the present invention, it is possible to provide a sealing device that exhibits good sealing performance over a long period of time.

  Further, in the case where the cylindrical guide is formed by integrally forming the flange portion radially outward from one axial end portion of the cylindrical portion, the cylindrical guide and the flange portion have a substantially L-shaped cross section. Depending on the structure, the cylindrical portion takes charge of the guide portion and the flange portion takes charge of the held portion. Therefore, by adding one L-shaped part, it is possible to easily realize a structure that narrows the radial width of the flow path between the oil seal and the spiral groove.

  In addition, by making the inner peripheral surface of the cylindrical guide slidably contact the top of the screw thread, the flow rate and flow rate of the air flow can be further increased. Even if there is concern about the occurrence of sliding noise, increasing the sliding torque or generating sliding noise by making the inner peripheral surface of the cylindrical guide face the top of the thread via a small radial gap. It is possible to increase the air flow rate and flow velocity as much as possible.

Sectional drawing of the principal part of the sealing device which concerns on the Example of this invention. Sectional drawing of the principal part of the sealing device which concerns on the other Example of this invention. Sectional drawing of the principal part of the sealing device which concerns on a prior art example

The present invention includes the following embodiments.
(1) A spiral screw groove is installed on the atmosphere side shaft of the lip, and external air is supplied to lower the lip temperature, and the lip is raised by raising the internal pressure on the lip atmosphere side by supplying air. , Tension force decreases and sliding heat generation decreases.
(2) Cool air is supplied by a spiral screw to lower the temperature near the lip. By supplying air, the internal pressure on the lip atmosphere side is made higher than that on the lip oil side, and the lip tension force during high rotation is lowered to keep sliding heat generation low.

  Next, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1: has shown the principal part cross section of the sealing device which concerns on the Example of this invention, and the sealing device which concerns on the said Example is comprised as follows.

  That is, the sealing device has an oil seal 1 disposed between the housing 11 and the rotating shaft 21, and the oil seal 1 is disposed toward the sealing fluid side A and the outer peripheral surface 21 a of the rotating shaft 21. And a sealing lip 4 for slidably and closely sealing the sealing fluid. The rotating shaft 21 is a hollow shaft. A spiral groove 22 is provided in a portion of the outer peripheral surface 21a of the rotating shaft 21 that is closer to the atmosphere B than the sliding portion with the seal lip 4, and this spiral groove 22 generates an air flow toward the seal lip 4 when the shaft rotates. The seal lip 4 is cooled by this air flow and pressure is applied to the seal lip 4. Further, a cylindrical guide (slinger / fixing flange) 6 for narrowing the radial width of the air flow passage 7 is disposed on the outer periphery of the spiral groove 22, and this cylindrical guide 6 is held by the oil seal 1. Projects radially inward from the oil seal 1.

  Hereinafter, details will be described for each component.

  First, the oil seal 1 is obtained by attaching (vulcanizing and bonding) a rubber-like elastic body 3 to a metal ring 2 and is fitted to the inner peripheral surface of the shaft hole 11a of the housing 11 with a predetermined fitting allowance. Yes. Of these, the metal ring 2 has a flange portion (inward flange portion) 2b extending radially inward from the end of one of the cylindrical portions (outer peripheral tube portion) 2a in the axial direction (left side or the atmosphere side B in the figure). Are integrally formed and have an L-shaped cross section. The rubber-like elastic body 3 is attached to the outer peripheral surface of the cylindrical portion 2a of the metal ring 2 to seal between the metal ring 2 and the housing 11, and to one end surface in the axial direction of the flange portion 2b. The outer end surface rubber portion 3b that is attached, the inner end surface rubber portion 3c that is attached to the end surface of the flange portion 2b in the other axial direction (right side, ie, the sealing fluid side A), and the inner peripheral surface of the cylindrical portion 2a The seal lip 4 is integrally formed from the inner peripheral end portion of the inner end face rubber portion 3c toward the other in the axial direction. The seal lip 4 has its lip end 4a slidably brought into close contact with the outer peripheral surface 21a of the rotary shaft 21 to seal the sealing fluid. The outer periphery of the lip end 4a is used for adjusting the tightening margin for the rotary shaft 21. The garter spring 5 is fitted.

  The rotating shaft 21 has a cylindrical outer peripheral surface 21a having a predetermined axial length, and a spiral groove 22 is provided in a portion of the outer peripheral surface 21a closer to the atmosphere B than a sliding portion with the seal lip 4. . The spiral groove 22 is spirally cut in such a direction as to generate an air flow toward the seal lip 4 when the shaft is rotated. The air flow cools the seal lip 4 and applies a high pressure to the seal lip 4. Note that the spiral groove 22 is provided only in a portion of the outer peripheral surface 21a of the rotating shaft 21 that is closer to the atmosphere B than the sliding portion with the seal lip 4, and the sliding portion with the seal lip 4 is provided with a screw. There is no cylindrical surface left.

  The cylindrical guide 6 is formed by integrally forming a flange portion (outward flange portion) 6b from one end in the axial direction of the cylindrical portion (inner peripheral cylindrical portion) 6a toward the radially outer side, and has a cross-section L. It is formed in a letter shape. Of these, the cylindrical portion 6 a is a guide portion that is coaxially disposed on the outer periphery of the spiral groove 22 in order to narrow the radial width of the flow path 7, while the flange portion 6 b is to be held by the oil seal 1. It is a held portion assembled to the oil seal 1, and is specifically held in a state of being sandwiched between the flange portion 2b of the metal ring 2 and the inner end rubber portion 3c in the oil seal 1.

  The cylindrical guide 6 is formed of a predetermined resin material having excellent wear resistance, and its inner peripheral surface 6c is slidably in contact with the top of the screw thread forming the spiral groove 22. .

  The sealing device having the above-described configuration is for sealing so that the sealing fluid does not leak from the sealing fluid side A to the atmosphere side B. When the rotating shaft 21 rotates, the spiral groove provided on the outer peripheral surface 21a of the rotating shaft 21 is provided. The rotation of the spiral groove 22 generates an air flow toward the seal lip 4. The seal lip 4 is slidably in close contact with the outer peripheral surface 21 a of the rotating shaft 21, and an air flow is blown onto the atmosphere side surface of the seal lip 4 to cool (air-cool) the seal lip 4. It is possible to prevent the heat generated by sliding with the rotary shaft 21 from being stored. Further, since a high pressure acts on the atmosphere side surface (slope) of the seal lip 4 due to the air flow and tries to lift the seal lip 4 from the rotary shaft 21, the force of the seal lip 4 against the rotary shaft 21 is reduced, and the sliding Dynamic fever itself is also reduced. Since the cylindrical guide 6 is disposed on the outer periphery of the spiral groove 22, the flow path 7 is set to be narrow, and thus the air flow is increased in flow rate and flow velocity. The effect is great. Accordingly, since the seal lip 4 is directly cooled and the sliding heat generated in the seal lip 4 itself is reduced in this way, it is possible to suppress the heat deterioration and the sliding wear on the seal lip 4, Durability is improved. In addition, the spiral groove 22 is provided only in a portion of the outer peripheral surface 21a of the rotary shaft 21 on the atmosphere side B from the sliding portion with the seal lip 4, and the seal lip 4 is provided on the rotary shaft 21 in which the spiral groove 22 is not provided. Since it contacts the cylindrical surface, so-called stationary leakage is suppressed. Therefore, good sealing performance is exhibited over a long period of time.

  In the above embodiment, the cylindrical guide 6 is formed of a predetermined resin material having excellent wear resistance, and its inner peripheral surface 6c is slidably in contact with the top of the thread forming the spiral groove 22. In the case where the cylindrical guide 6 is formed of, for example, a metal material and there is a concern about an increase in sliding torque or generation of sliding contact noise, as shown in FIG. It is preferable that the inner peripheral surface 6c of the guide 6 is opposed to the top of the screw thread via a minute radial gap d (non-contacting), thereby increasing sliding torque and generating sliding contact noise. In addition, the cooling effect and the tension reducing effect can be exhibited.

DESCRIPTION OF SYMBOLS 1 Oil seal 2 Metal ring 2a, 6a Cylindrical part 2b, 6b Flange part 3 Rubber elastic body 3a Outer rubber part 3b, 3c End surface rubber part 3d Inner peripheral rubber part 4 Seal lip 4a Lip end 5 Gutter spring 6 Cylindrical guide 6c Inner peripheral surface 7 Flow path 11 Housing 11a Shaft hole 21 Rotating shaft 21a Outer peripheral surface 22 Spiral groove

Claims (4)

Having an oil seal disposed between the housing and the rotating shaft;
The oil seal has a seal lip that is arranged toward the sealing fluid side and seals the sealing fluid in close contact with the outer peripheral surface of the rotating shaft in a slidable manner,
The rotating shaft has a spiral groove in a portion closer to the atmosphere than a sliding portion with the seal lip on an outer peripheral surface thereof, and the spiral groove generates an air flow toward the seal lip when rotating. Cooling the seal lip with the air flow and applying pressure to the seal lip;
A sealing device, wherein a cylindrical guide for narrowing a radial width of the air flow channel is disposed on an outer periphery of the spiral groove, and the cylindrical guide is held by the oil seal. The sealing device according to claim 1.
The cylindrical guide is formed by integrally forming a flange portion radially outward from one axial end of the cylindrical portion, and the cylindrical portion narrows the radial width of the flow path. And a flanged portion to be held by the oil seal. The sealing device according to claim 1 or 2,
The cylindrical guide has its inner peripheral surface slidably in contact with the top of a screw thread that forms the spiral groove. The sealing device according to claim 1 or 2,
The cylindrical guide has a sealing device characterized in that an inner peripheral surface of the cylindrical guide is opposed to a top of a screw thread forming the spiral groove through a minute radial gap.

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