JP4466842B2 - Sealing device - Google Patents

Description

  The present invention relates to a sealing device that seals the outer periphery of a rotating body, and more particularly to a device that seals with a sealing lip.

As a kind of sealing device that seals the shaft periphery of the rotating shaft, the inner peripheral surface of the seal lip made of synthetic resin with low friction coefficient such as PTFE mounted on the inner periphery of the housing can be slid on the outer peripheral surface of the rotating shaft There is something to close. However, since a synthetic resin such as PTFE is poor in elasticity, in order to compensate the tight force of the seal lip against the outer peripheral surface of the rotating shaft, for example, as disclosed in Patent Document 1, the seal lip is reduced in the diameter reducing direction. It is effective to provide a leaf spring for biasing.
JP 2001-65703 A

  That is, the sealing device (lip type seal) described in Patent Document 1 includes an annular leaf spring, and the leaf spring is divided into a large number of spring pieces in the circumferential direction by slits extending in the radial direction. The tip portions of the large number of spring pieces press the outer peripheral surface of the seal lip with an appropriate load, and compensate the tight force of the seal lip against the outer peripheral surface of the rotating shaft.

  However, in this type of sealing device, conventionally, a large number of spring pieces in the inner peripheral portion of the leaf spring are elastically deformed as a whole, and the seal lip is greatly displaced toward the inner peripheral side toward the tip, so that the outer peripheral surface of the rotary shaft The contact surface pressure of the seal lip with respect to the maximum becomes maximum on the tip end side, and there is a possibility that the wear progresses at an early stage. For this reason, if a spiral groove is formed on the inner peripheral surface of the tip of the seal lip to generate a pumping force that pushes the fluid back into the machine by hydrodynamic action during shaft rotation, this groove disappears early due to wear. And there exists a possibility that the sealing function by the pump force may be impaired.

  The present invention has been made in view of the above points, and the technical problem thereof is that the surface pressure is locally increased by the spring member that compensates for the tight force of the seal lip, resulting in early wear. It is to prevent.

As a means for effectively solving the technical problem described above, the sealing device according to the invention of claim 1 is such that the inner peripheral surface of the inner peripheral cylindrical portion extending in a cylindrical shape is slidable with the outer peripheral surface of the rotating body. A seal lip to be brought into contact, and a spring member for urging the inner peripheral cylindrical portion in the diameter reducing direction, and the spring member projects to the outer peripheral flange and the inner peripheral side thereof at predetermined intervals in the circumferential direction. Each of the spring protrusions extends from the inner periphery of the outer peripheral flange in a belt shape and can be elastically bent and deformed, and extends from the tip thereof to the outer peripheral surface of the inner peripheral cylindrical portion. Is formed of a non-deformable pressing piece that presses the inner peripheral cylindrical portion of the seal lip from the outer periphery over substantially the entire area in the axial direction and closely contacts the outer peripheral surface of the rotating body.

In the sealing device having the above configuration, the inner peripheral surface of the inner peripheral cylindrical portion of the seal lip mounted on the housing side is slidably in close contact with the outer peripheral surface of the rotating body, thereby sealing between the housing and the rotating body. This prevents fluid leakage from the space. The spring member compensates the tightening force of the inner peripheral cylindrical portion of the seal lip against the outer peripheral surface of the rotating body. The large number of spring protrusions formed on the spring member are elastically deformed by the leaf spring portion. Thus, the non-deformable pressing piece extending in the form of an arc from its tip is brought into close contact with the outer peripheral surface of the inner peripheral cylindrical portion of the seal lip and presses the inner peripheral cylindrical portion from the outer periphery over substantially the entire area in the axial direction. Therefore, almost uniform tension can be obtained.

  According to the sealing device of the first aspect of the present invention, since the pressing force applied to the inner peripheral cylindrical portion of the seal lip is made uniform by the spring member, early local wear of the seal lip due to an increase in local surface pressure is prevented. It can be effectively prevented.

  Hereinafter, a sealing device according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view of a preferred embodiment of a sealing device cut along a plane passing through its axis to show a partial appearance of a seal lip and a spring member, and FIG. 2 is a cross-sectional view of FIG. FIG. 3 is a perspective view showing a part of the spring member in FIG. 1 together with a part of the seal lip.

  First, as shown in FIG. 1, a sealing device according to this embodiment includes an outer ring 1 integrally having an elastic seal 2, an inner ring 3 press-fitted to the inner periphery thereof, and the inner ring 3 and the outer ring 1. The seal lip 4 is fixed between the inner peripheral cylindrical portion 41 and the inner peripheral surface of the inner peripheral cylindrical portion 41 is slidably brought into close contact with the outer peripheral surface of the rotating body (not shown). It consists of a spring member 5 that urges the circumferential tubular portion 41 in the direction of diameter reduction.

  Specifically, the outer ring 1 is manufactured by stamping and pressing a metal plate, and includes a sleeve 11 and an inward flange 12 extending from one end thereof to the inner peripheral side, that is, a plane passing through the axis. The cut cross-sectional shape (cross-sectional shape in FIG. 1) is substantially L-shaped. Similarly to the outer ring 1, the inner ring 3 is manufactured by stamping and pressing a metal plate. The inner ring 3 is press-fitted to the inner periphery of the sleeve 11 of the outer ring 1, and one end thereof is connected to the inner peripheral side. The cross-sectional shape (cross-sectional shape of FIG. 1) cut | disconnected by the plane which passes through the inward flange 32 extended to, ie, passes through an axial center, has comprised the substantially L shape.

  The elastic seal 2 is made of a rubber-like elastic material, and includes an outer peripheral seal portion 21 integrally vulcanized and bonded to the outer periphery of the sleeve 11 of the outer ring 1, and an inward flange 12 of the outer ring 1. It comprises a dust strip 22 integrally vulcanized and bonded to the inner peripheral portion, and an intermediate elastic layer 23 integrally vulcanized and bonded to both surfaces of the inward flange 12. That is, the elastic seal 2 is defined between the inner surface of the mold and the outer ring 1 in a clamped state by setting the outer ring 1 to which a vulcanized adhesive has been applied in advance in a predetermined mold (not shown). An unvulcanized rubber material is filled in the annular cavity thus formed and heated and pressurized so that it is integrally vulcanized and bonded to the outer ring 1 simultaneously with molding.

  The seal lip 4 is made of a synthetic resin material having a low coefficient of friction that is superior in heat resistance and wear resistance to a rubber-like elastic material, typically PTFE (Poly Tetra Fluoro Ethylene). And an inner peripheral cylindrical portion 41 extending in a cylindrical shape so as to face the inner side of the machine to be sealed in a mounted state from the outer peripheral portion 42 that forms a plane perpendicular to the shaft center and the curved portion 43 therefrom. Have. The seal lip 4 is formed at the outer peripheral portion 42 between the back surface 23 a of the intermediate elastic layer 23 bonded to the inward flange 12 of the outer ring 1 and the inward flange 32 of the inner ring 3. The inner peripheral surface of the inner peripheral cylindrical portion 41 is slidably in close contact with the outer peripheral surface of the rotating shaft (not shown). In addition, a spiral groove 41a is formed on the inner peripheral surface of the inner peripheral cylindrical portion 41. The spiral groove 41a generates a pumping force that pushes fluid toward the distal end side of the inner peripheral cylindrical portion 41 by a hydrodynamic action when the shaft rotates. .

  The spring member 5 is made of a metal plate such as spring steel or a synthetic resin material, and as shown in FIGS. 2 and 3, an outer peripheral flange 51 that forms a plane perpendicular to the axial center, It consists of a large number of spring protrusions 52 projecting circumferentially at predetermined intervals in the circumferential direction. Each spring protrusion 52 extends from the inner periphery of the outer peripheral flange 51 to bend in the axial direction and can be elastically bent and deformed, and extends from the tip thereof to the inner peripheral cylindrical portion of the seal lip 4. It consists of an undeformed pressing piece 522 that presses 41 from the outer periphery to bring it into close contact with the outer peripheral surface of the rotating shaft. The leaf spring portion 521 is preformed so as to bend in the axial direction from the inner periphery of the outer peripheral flange 51, and each pressing piece 522 is disposed on the outer peripheral surface of the inner peripheral cylindrical portion 41 of the seal lip 4 in the axial length. The tip of each pressing piece 522 is substantially flush with the tip of the inner peripheral cylindrical portion 41 of the seal lip 4.

  The outer peripheral flange 51 of the spring member 5 is sandwiched and fixed between the back surface 23 a of the intermediate elastic layer 23 of the elastic seal 2 and the inward flange 32 of the inner ring 3 in a state of being overlapped with the outer peripheral portion 42 of the seal lip 4. ing. The pressing piece 522 in each spring protrusion 52 forms an arc surface having a curvature corresponding to the outer peripheral surface of the inner peripheral cylindrical portion 41, and the entire surface can be in close contact with the outer peripheral surface of the inner peripheral cylindrical portion 41. The leaf spring portion 521 of each spring protrusion 52 extends in a band shape between the outer peripheral flange 51 extending in the radial direction and the pressing piece 522 extending in the axial direction and having a smaller width in the circumferential direction than the pressing piece 522. An appropriate spring load is generated by being bent and deformed.

  Further, as described above, each spring protrusion 52 is bent and deformed by the elongated strip-shaped leaf spring portion 521 to generate a spring load, and the pressing piece 522 is wider than the leaf spring portion 521 and is sealed. Since it forms a circular arc surface corresponding to the outer peripheral surface of the inner peripheral cylindrical portion 41 of the lip 4, it is hardly bent and deformed. For this reason, the pressing piece 522 that receives the spring load of the leaf spring portion 521 presses the inner peripheral cylindrical portion 41 almost uniformly from the outer periphery to compensate for the pressing force on the rotating shaft.

  In the sealing device of the present invention configured as described above, the inner peripheral cylindrical portion 41 of the seal lip 4 faces the inside of the machine to be sealed between the housing (not shown) and the rotary shaft inserted therethrough. The outer peripheral seal portion 21 of the elastic seal 2 reinforced by the outer ring 1 is press-fitted to the inner peripheral surface of the housing with an appropriate crushing margin, and the inner peripheral cylindrical portion 41 of the seal lip 4 is fitted. The inner peripheral surface of this is slidably brought into close contact with the outer peripheral surface of the rotating shaft, thereby providing a sealing function. In addition, the pump groove pressure in which the spiral groove 41a formed on the inner peripheral surface of the inner peripheral cylindrical portion 41 feeds the fluid toward the distal end side (in-machine space side) of the inner peripheral cylindrical portion 41 by the rotation of the rotation shaft. (Screw pump action) is generated, and the sealing target fluid that passes through the space between the seal lip 4 and the rotating shaft and leaks to the atmosphere outside the machine is pushed back to the inside of the machine. Can do.

  On the other hand, the dust lip 22 is slidably close to or close to the rotating shaft, thereby preventing dust from entering the space inside the machine.

  Further, the inner peripheral cylindrical portion 41 of the seal lip 4 made of PTFE having poor elasticity is compensated for the pressing force against the rotating shaft by the spring member 5, so that the contact surface pressure of the inner peripheral cylindrical portion 41 due to the settling or the like is reduced. It is possible to prevent the deterioration, maintain the required sealing performance, and obtain good followability to the eccentric motion (axial runout) of the rotating shaft.

  In addition, the large number of spring protrusions 52 formed on the spring member 5 are such that the leaf spring portion 521 is elastically bent and deformed, so that the undeformed wide pressing piece 522 becomes the inner peripheral tubular portion 41 of the seal lip 4. Is pressed from the outer periphery over the entire region in the axial direction, so that a substantially uniform tightening force can be obtained. For this reason, the surface pressure distribution with respect to the outer peripheral surface of the rotating shaft becomes uniform, and it is possible to effectively prevent the early local wear due to the local surface pressure increase and the early disappearance of the spiral groove 41a.

FIG. 3 is a cross-sectional view of a preferred embodiment of the sealing device, cut along a plane passing through its axis, showing a partial appearance of the seal lip and the spring member and partially omitting it. It is an axial direction projection view of the spring member in FIG. It is a perspective view which shows a part of spring member in FIG. 1 with a part of seal lip.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Outer ring 11, 31 Sleeve 12, 32 Inward flange 2 Elastic seal 21 Outer peripheral seal part 22 Dustrip 23 Intermediate elastic layer 3 Inner ring 4 Seal lip 41 Inner peripheral cylindrical part 41a Spiral groove 42 Outer peripheral part 43 Curved part 5 Spring member 51 Outer peripheral flange 52 Spring protrusion 521 Leaf spring portion 522 Pressing piece

Claims (1)

A seal lip (4) in which the inner peripheral surface of the inner peripheral cylindrical portion (41) extending in a cylindrical shape is slidably brought into close contact with the outer peripheral surface of the rotating body, and the inner peripheral cylindrical portion (41) is reduced in diameter. A spring member (5) for biasing to the outer peripheral flange, and the spring member (5) comprises an outer peripheral flange (51) and a plurality of spring protrusions (52) protruding toward the inner peripheral side at predetermined intervals in the circumferential direction. The spring protrusions (52) extend from the inner periphery of the outer peripheral flange (51) in a strip shape and can be elastically bent and deformed, and the spring protrusions (52) extend from the tip of the inner peripheral cylindrical portion ( 41) is a non-deformable pressing piece that forms an arc surface whose entire surface is in intimate contact with the outer peripheral surface, and presses the inner peripheral cylindrical portion (41) from the outer periphery over substantially the entire area in the axial direction to closely contact the outer peripheral surface of the rotating body. (522) The sealing device characterized by comprising.

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