JP2016040472A - Sealing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively prevent leakage, in a sealing device having a seal lip 2 in which screw ridges 24, 25 are arranged so as to reversely oppose each other in a circumferential direction.SOLUTION: A sealing device comprises a seal lip 2 which is oriented to a sealing space A side. A lip tip 21 which slidably and closely contacts with an external peripheral face of a rotating body, and an anti-sealing space-side conical face 23 which is enlarged in diameter toward an anti-sealing space B side from the lip tip 21 are formed at an internal peripheral face of the seal lip 2, a first screw ridge 24 which extends while inclining to a constant direction with respect to the circumferential direction, and a second screw ridge 25 which extends while inclining to a reverse direction of the first screw ridge 24 are formed at the anti-sealing space-side conical face 23, and necessary numbers of auxiliary ridges 26, 27 are formed at both side faces of the first screw ridge 24 and the second screw ridge 25. The auxiliary ridges 26, 27 extend to an opposite side of the lip tip 21 while forming an acute angle with respect to an extension direction of the first screw ridge 24, or the second screw ridge 25.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a sealing device that seals the outer periphery of a rotating body of a device with a seal lip, and particularly relates to a seal lip formed with a threaded ridge for obtaining a sealing performance by a screw pump action.

  FIG. 4 shows a typical conventional example of this type of sealing device. That is, the sealing device 100 shown in FIG. 4 includes a seal lip 110 integrally formed of a rubber-like elastic material (rubber material or synthetic resin material having rubber-like elasticity) on a metal reinforcing ring 120. On the inner peripheral surface of the lip 110, a conical surface 112 on the sealed space side having a large diameter toward the sealed space (inside the machine) A side with the lip tip 111 having the smallest diameter as a boundary, and the anti-sealed space B side (sealed space A The opposite sealing side conical surface 113 having a large diameter is formed, and a number of first screw protrusions 114 and second screw protrusions 115 are formed on the anti-sealing space side conical surface 113. ing. The first screw ridges 114 and the second screw ridges 115 are provided so as to be alternately opposite to each other in the circumferential direction with a plurality of sets as a set. In addition, a garter spring 130 for compensating the tight force is attached to the outer peripheral portion of the seal lip 110.

  That is, the sealing device having the above-described configuration is tightly fitted and fixed to the inner peripheral surface of a housing (not shown), and the lip tip 111 having the inner diameter of the seal lip 110 is slidably brought into close contact with the outer peripheral surface of the rotary shaft 200. It functions and prevents the oil in the sealed space A from leaking from the shaft periphery to the anti-sealed space B. Then, the screw pump action in which one of the first screw protrusion 114 and the second screw protrusion 115 is in the forward direction with respect to the rotation of the rotating shaft 200 with respect to the rotation of the rotating shaft 200 in either forward or reverse direction. Therefore, the oil that tries to leak the sliding portion between the lip tip 111 of the seal lip 110 and the rotary shaft 200 from the sealed space A to the anti-sealed space B is pushed back to the sliding portion side by the forward screw pump action. Therefore, a good sealing function can be exhibited.

Japanese Unexamined Patent Publication No. 1-312274

  However, according to the above conventional sealing device, the forward screw pump action in which one of the first screw ridge 114 and the second screw ridge 115 pushes the oil to be leaked back to the sealed space A side. However, the other threaded ridge inclined in the opposite direction has an action of scraping out the oil film interposed between the lip tip 111 and the sliding portion of the rotating shaft 200 slightly by the reverse screw pump action. There is concern about inducing leakage.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a sealing device in which screw ridges are provided on the seal lip so that the thread ridges are alternately reversed in the circumferential direction. It is to prevent effectively.

The present invention employs the following means in order to achieve the above-described object.
That is, the sealing device of the present invention includes a seal lip facing the sealed space side, a lip tip slidably in contact with the outer peripheral surface of the rotating body on the inner peripheral surface of the seal lip, and the lip tip opposite from the lip tip. An anti-sealing space side conical surface having a large diameter toward the sealed space side is formed, and a first threaded ridge extending on the anti-sealing space side conical surface in an inclined direction with respect to the circumferential direction, A second threaded ridge extending in the opposite direction to the first threaded ridge is formed, and a required number of auxiliary ridges are formed on both sides of the first threaded ridge and the second threaded ridge, The auxiliary ridge extends at an acute angle with respect to the extending direction of the first screw ridge or the second screw ridge to the side opposite to the lip tip (Claim 1).

  In the above configuration, when the rotating body rotates in either the forward or reverse direction, one of the first screw protrusion and the second screw protrusion anti-seal the seal lip and the sliding portion of the rotating body from the sealed space. A forward screw pumping action that pushes the fluid that is about to leak into the space back to the sealed space side is achieved. The other of the first screw ridge and the second screw ridge has the effect of slightly scraping off the oil present in the sliding portion of the lip tip and the rotating body by the reverse screw pump action. The fluid scraped out by is easily trapped by the auxiliary ridges formed on both side surfaces of one screw ridge having a forward screw pump action, and the captured fluid is transferred to the screw ridge having a forward screw pump action. Since it is guided, it is returned to the sealed space side by the forward screw pump action of this screw ridge.

The present invention may further employ the following means in order to achieve the above object.
That is, in the sealing device having the above configuration (Claim 1), the first screw ridge and the second screw ridge are increased in width and height from the anti-sealing space side conical surface toward the opposite side of the lip tip. The auxiliary ridge extends from the flange portion of the first screw ridge or the second screw ridge toward the skirts on both sides thereof. (Claim 2).

  By forming the first screw ridge and the second screw ridge in a boat bottom shape, the contact area of the flange portion of the first screw ridge and the second screw ridge with respect to the outer peripheral surface of the rotating body becomes long. The directional screw pumping action can be enhanced, and for this reason, the fluid trapping action by the auxiliary protrusion extending from the flange portion can also be enhanced.

  According to the sealing device according to the present invention, even if leakage fluid is generated by the screw ridge that causes the reverse screw pump action during rotation of the rotating body among the first screw ridge and the second screw ridge, Leakage fluid is captured by the auxiliary ridge formed on the screw ridge that causes the forward screw pump action, and is returned to the lip tip by the forward screw pump action. Excellent sealing performance can be achieved.

1 is a half sectional view showing a preferred embodiment of a sealing device according to the present invention by cutting along a plane passing through its axis. FIG. 2 is a partial development view of an inner peripheral surface of a seal lip in FIG. 1. FIG. 2 is a partial development view showing a close region of a seal lip with respect to an outer peripheral surface of a rotating shaft in FIG. It is a half sectional view which cuts and shows an example of the sealing device by a prior art by the plane which passes along the axial center.

  Hereinafter, preferred embodiments of a sealing device according to the present invention will be described with reference to the drawings. In the sealing device shown in FIG. 1, a seal lip 2 made of a rubber-like elastic material (rubber material or synthetic resin material having rubber-like elasticity), a dust lip 3 and an outer peripheral seal portion 4 are integrated with a metal reinforcing ring 1. It is molded. Further, a garter spring 5 is mounted on the outer periphery in the vicinity of the tip of the seal lip 2.

  The reinforcing ring 1 is manufactured by punching and stamping a steel plate or the like, and has an outer diameter cylindrical portion 11 and an inner diameter side from the end that is the anti-sealing space B side of the outer diameter cylindrical portion 11 in the mounted state. It has an inwardly extending flange portion 12 extending to the end, that is, has a substantially L-shaped cross section.

  The seal lip 2 extends from the inner diameter end of the inward flange portion 12 of the reinforcing ring 1 in a direction toward the sealed space A in the mounted state, and slides on the inner periphery near the tip with the outer peripheral surface 200a of the rotary shaft 200. A lip tip 21 movably brought into close contact, a sealed space side conical surface 22 having a large diameter toward the sealed space A with the lip tip 21 as a boundary, and a large diameter toward the opposite side of the sealed space A An anti-sealed space side conical surface 23 is formed. Accordingly, the lip tip 21 positioned between the conical surfaces 22 and 23 has a substantially V-shaped cross section. The rotating shaft 200 corresponds to the rotating body described in claim 1.

  The anti-sealed space side conical surface 23 of the seal lip 2 has a first screw protrusion 24 extending at a predetermined inclination angle with respect to the circumferential direction (extension direction of the lip tip 21), and the first screw protrusion. A second threaded ridge 25 extending obliquely in the direction opposite to 24 is formed.

  The first screw ridge 24 and the second screw ridge 25 each have a boat-shaped raised shape, and one end thereof reaches the lip tip 21. Specifically, each of the first screw protrusion 24 and the second screw protrusion 25 has a chevron-shaped cross section perpendicular to the extending direction, and has flange portions 24a and 25a at the center in the width direction as shown in FIG. The width and the height of the flanges 24a and 25a (the height of the protrusion from the conical surface 23 on the anti-sealing space side) are gradually changed so as to become maximum at the intermediate portion in the longitudinal direction, that is, the length from the lip tip 21 side In the middle of the direction, the height and width of the bulge increase toward the opposite side of the lip tip 21. The first screw protrusions 24 and the second screw protrusions 25 are provided alternately in the circumferential direction with a plurality of threads as a set.

  Each of the first screw ridges 24 is formed with a plurality of auxiliary ridges 26 extending on both side inclined surfaces 24c, 24c from the flange portion 24a toward the skirt portions 24b, 24b on both sides thereof. Similarly, a plurality of auxiliary protrusions 27 are formed extending from the flange portion 25a toward the skirt portions 25b and 25b on both sides thereof on both inclined surfaces 25c and 25c. These auxiliary protrusions 26 and 27 extend at an acute angle with respect to the extending direction of the first screw protrusion 24 or the second screw protrusion 25 on the side opposite to the lip tip 21.

  The dust lip 3 extends in the shape of a conical cylinder from the position on the inner peripheral side of the inward flange portion 12 of the reinforcing ring 1 to the side opposite to the seal lip 2 (the direction facing the anti-sealing space B in the mounted state). The inner diameter of the part is slightly larger than the outer peripheral surface 200 a of the rotating shaft 200, that is, a slight gap δ is formed between the outer peripheral surface 200 a of the rotating shaft 200. This gap δ is a negative pressure caused by the forward screw pump action of the first screw protrusion 24 or the second screw protrusion 25 in the annular space C defined by the seal lip 2 and the dust lip 3 on the outer periphery of the rotating shaft 200. It is to prevent becoming.

  The fixed seal portion 4 is continuous with the seal lip 2 and the dust lip 3 and is formed on the outer peripheral side of the outer diameter cylindrical portion 11 of the reinforcing ring 1. It is tightly fitted and fixed in a compressed state.

  The garter spring 5 is formed by connecting metal coil springs in an annular shape, and is fitted on the outer peripheral side of the lip tip 21 of the seal lip 2.

  In the sealing device having the above configuration, the fixed seal portion 4 is press-fitted and attached to the inner peripheral surface of the housing (not shown) so that the seal lip 2 faces the sealed space A side, and the lip tip 21 of the seal lip 2 is The oil in the sealed space A is prevented from leaking from the shaft periphery to the anti-sealed space B side by being slidably in contact with the outer peripheral surface 200a of the rotating shaft 200.

  Here, assuming that the outer peripheral surface 200a is moved in the R direction of FIG. 2 due to the normal rotation of the rotating shaft 200, the fluid existing on the outer periphery of the rotating shaft 200 is also the outer peripheral surface 200a of the rotating shaft 200. The first screw ridge 24 and the second thread 24 formed on the anti-sealing space side conical surface 23 on the side of the anti-sealing space B from the lip end 21 of the sealing lip 2 Among the screw ridges 25, the first screw ridge 24 has a forward screw pump action in the R direction, that is, a screw pump action that feeds fluid that rotates in the R direction to the sealed space A side as indicated by a broken arrow F 1. Provoke. For this reason, even if a part of the sealing target oil existing in the sealed space A passes through the sliding portion of the lip tip 21 and leaks to the anti-sealed space B side, this leaked oil is in the order of the first screw ridge 24. It is pushed back to the sealed space A side by the directional screw pump action.

  Moreover, the first screw protrusion 24 and the second screw protrusion 25 have a boat bottom shape, and the heights of the flange portions 24a and 25a are directed from the end portion on the lip tip 21 side toward the longitudinal intermediate portion. Since it gradually increases, the contact lengths of the flange portions 24a and 25a with respect to the outer peripheral surface 200a of the rotating shaft 200 become relatively long, and as a result, it is possible to enhance the oil leakage push-back effect by the forward screw pump action. .

  On the other hand, the second threaded ridge 25 is a screw that scrapes the fluid that rotates in the reverse direction with respect to the rotation direction of the rotating shaft 200, that is, the fluid that rotates in the R direction, to the anti-sealing space B side as indicated by the arrow F2. Induces pumping action. However, the oil thus scraped from the sliding portion of the lip tip 21 toward the anti-sealing space B side is captured by the auxiliary protrusion 26 on the first screw protrusion 24 side that causes the forward screw pump action. The first screw protrusion 24 is pushed back to the sealed space A side by the forward screw pump action.

  This will be described in more detail. FIG. 3 shows a close region of the seal lip with respect to the outer peripheral surface 200a of the rotating shaft 200, that is, as indicated by a broken arrow F2 in FIG. 3, the rotating shaft 200 in the R direction. The oil scraped from the sliding portion 21S of the lip tip 21 by the reverse screw pump action of the second screw protrusion 25 during rotation is dragged to the outer peripheral surface 200a of the rotating shaft 200 and rotates together with the forward screw. The auxiliary ridge 26 on the side of the first screw ridge 24 causing the pump action is captured as indicated by a broken arrow F3, and further guided to the flange portion 24a of the first screw ridge 24 by the auxiliary ridge 26. The forward screw pump action returns to the sliding portion 21S of the lip tip 21 as indicated by the dashed arrow F1.

  Further, when the outer peripheral surface 200a is moved to the opposite side to the R direction in FIG. 2 due to the rotation of the rotary shaft 200, the second screw protrusion 25 acts as a forward screw pump, The screw pumping action that feeds the co-rotating fluid to the sealed space A side is caused, and the first screw protrusion 24 causes the reverse screw pump action, that is, the screw pump action that scrapes the co-rotating fluid to the anti-sealing space B side. .

  In this case as well, even if oil is scraped out from the sliding portion 21S of the lip tip 21 to the anti-sealing space B side by the reverse screw pump action by the first screw protrusion 24, this oil leakage will be caused by the second screw protrusion. It is captured by the auxiliary ridge 27 on the side of the ridge 25, and further guided to the flange portion 25a of the second screw ridge 25 by the auxiliary ridge 27, and to the sliding portion 21S of the lip tip 21 by its forward screw pump action. Returned.

  Therefore, leakage of the oil to be sealed to the anti-sealing space B side is effectively prevented regardless of the rotation direction of the rotating shaft 200.

DESCRIPTION OF SYMBOLS 1 Reinforcement ring 2 Seal lip 21 Lip tip 23 Anti-sealing space side conical surface 24 First screw ridges 24a, 25a ridges 24b, 25b skirt 25 Second screw ridges 26, 27 Auxiliary ridges

Claims (2)

  A seal lip facing the sealed space side is provided, and a lip tip that is slidably in contact with the outer peripheral surface of the rotating body is provided on the inner peripheral surface of the seal lip, and a large diameter from the lip tip toward the anti-sealed space side. An anti-sealing space-side conical surface is formed, and the anti-sealing space-side conical surface extends in a predetermined direction with respect to the circumferential direction, and a first screw protrusion, and a direction opposite to the first screw protrusion A second threaded ridge is formed extending in a slanted direction, and a required number of auxiliary ridges are formed on both side surfaces of the first threaded ridge and the second threaded ridge, respectively. A sealing device characterized by extending at an acute angle with respect to the extending direction of the first screw projection or the second screw projection to the opposite side. The first screw ridge and the second screw ridge have a boat bottom shape that gradually changes so that the width and the height of the bulge from the anti-sealed space side conical surface increase toward the opposite side of the lip tip. The auxiliary ridge extends from the flange portion of the first screw ridge or the second screw ridge toward the skirts on both sides thereof.

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