JP6442203B2 - Sealing device - Google Patents

Description

  The present invention relates to a sealing device that seals the outer periphery of a rotating body of a device such as an automobile with a seal lip, and more particularly to a device in which a protrusion for obtaining a sealing property by a screw seal action is formed on a seal lip.

  Conventionally, as shown in FIG. 4 and FIG. 5, a sealing device in which a protrusion for obtaining a screw sealing action is formed on a seal lip is known.

  4 includes a seal lip 100 formed of a rubber-like elastic material (rubber material or synthetic resin material having rubber-like elasticity), and the seal lip 100 has the smallest diameter on the inner peripheral surface thereof. With the lip edge 101 as a boundary, the sealed space side conical surface 102 having a larger diameter toward the sealed space (inside the machine) A side and the anti-sealed space side conical surface 103 having a larger diameter toward the anti-sealed space (outside the machine) B side. Are formed, and a plurality of first screw protrusions 104 and second screw protrusions 105 are formed on the conical surface 103 on the anti-sealing space side. The first screw ridge 104 and the second screw ridge 105 are provided such that the width and height are constant over the entire length, and a plurality of pairs are reversely arranged in the circumferential direction. (See, for example, Patent Document 1 below).

  Further, in the sealing device shown in FIG. 5, the first screw ridge 104 and the second screw ridge 105 are formed in a boat-bottom ridge shape in which the width and height are the largest in the middle portion in the longitudinal direction ( For example, see Patent Document 2 below).

  This type of sealing device is tightly fitted and fixed to the inner peripheral surface of a housing (not shown), and the lip edge portion 101 having the inner diameter of the seal lip 100 is slidably brought into close contact with the outer peripheral surface of the rotary shaft 200. It has a sealing function 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 104 and the second screw protrusion 105 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 the forward or reverse direction. Therefore, the oil that tries to leak the sliding portion of the seal lip 100 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, and a good sealing is achieved. Function can be demonstrated.

JP 2005-315398 A Japanese Patent No. 3278349

  However, in the sealing device shown in FIG. 4, the first screw protrusion 104 and the second screw protrusion 105 are worn together with the lip edge portion 101 of the seal lip 100, thereby reducing the forward screw pump action. There is concern.

  On the other hand, the sealing device shown in FIG. 5 can suppress a decrease in the forward screw pump action due to wear of the first screw ridge 104 and the second screw ridge 105, but on the other hand, the first screw ridge 104 and the second screw ridge 104. Of the screw ridges 105, the reverse screw pump action of the other screw ridge inclined in the direction opposite to that of the screw ridge having the forward screw pump action is enhanced. There is a risk of leakage due to the oil film scraping action.

  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 alternately provided in the circumferential direction in the seal lip so as to be opposite to each other in the circumferential direction. The purpose is to suppress a decrease in the forward screw pump action and to effectively prevent leakage due to the reverse screw pump action.

The sealing device of the present invention, the outer peripheral surface and a seal lip having a slidably brought into close contact with the lip edge, opposite to the sealed space side conical surface comprising a larger diameter toward the lip edge to the opposite sealed space side of the rotating body And extending from the lip edge in a fixed direction with respect to a circumferential direction in a sliding region in the vicinity of the lip edge in the anti-sealing space side conical surface. A first screw ridge having a substantially constant height, and a second screw having a substantially constant height from the lip edge extending in a direction opposite to the first screw ridge from the conical surface on the anti-sealing space side and ridges, is provided, wherein the anti-seal space side than the first screw projection in the anti-seal space side conical surface, so as to face an end portion on the first screw projection, the first threaded protrusion The height of the bulge from the conical surface on the side of the anti-sealing space extends in a direction opposite to The lip edge and larger third screw protrusion toward the opposite side is provided, wherein the anti-seal space side than the second screw ridges in the anti-seal space side conical surface, end to the second screw ridges A fourth threaded ridge that extends in a direction opposite to the second threaded ridge with the portion facing each other and the height of the bulge from the anti-sealed space side conical surface increases toward the opposite side of the lip edge. Is provided.

  In the above configuration, when the rotating body rotates in either the forward or reverse direction, one of the first threaded protrusion and the second threaded protrusion slides between the seal lip and the rotating body from the sealed space. A forward screw pumping action that pushes the fluid that is about to leak into the anti-sealed space back to the sealed space side is exhibited. The other screw ridge of the first screw ridge and the second screw ridge has a function of slightly scraping out oil intervening between the lip edge and the sliding portion of the rotating body by the reverse screw pump action. However, the fluid scraped out by this is pushed back to the lip edge side by the forward screw pump action of the third screw protrusion or the fourth screw protrusion formed on the anti-sealing space side from the other screw protrusion. . As the first screw ridge and the second screw ridge are worn along with the lip edge, the screw pump action by the first screw ridge and the second screw ridge is reduced, while the third screw ridge and the fourth screw ridge. The screw pump action due to the screw ridges is increasing, and the third screw ridge and the fourth screw ridge are increased in height toward the opposite side of the lip edge, so the contact length with the rotating body is long. Therefore, the required screw pumping action is maintained.

  According to the sealing device according to the present invention, the first screw protrusion and the second screw protrusion are good because the fluid scraping by the screw protrusion that causes the reverse screw pump action during rotation of the rotating body is suppressed. Initial sealability is ensured, and the screw pump action by the third and fourth screw ridges becomes prominent with the wear of the first and second screw ridges. be able to.

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 state in which wear on the inner peripheral surface of the seal lip in FIG. 1 has progressed. 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. It is a half sectional view which cuts and shows the other 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 edge 21 that is movably brought into close contact, a sealed space side conical surface 22 that increases in diameter toward the sealed space A with the lip edge 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. Therefore, the lip edge 21 located 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.

  A sliding region in the vicinity of the lip edge 21 on the anti-sealing space side conical surface 23 of the seal lip 2 extends from the lip edge 21 in an inclined direction with respect to the circumferential direction from the anti-sealing space side conical surface 23. The first threaded ridge 24 having a substantially constant height and width, and the height and width from the anti-sealed space side conical surface 23 extending from the lip edge 21 inclining in the opposite direction to the first threaded ridge 24. A substantially constant second threaded ridge 25 is formed, and the anti-sealed space B side of the anti-sealed space side conical surface 23 is positioned on the side opposite to the first threaded ridge 24 in a direction opposite to the first threaded ridge 24. A third threaded ridge 26 having a boat-bottomed bulge shape is formed to extend incline and the height and width of the bulge from the conical surface 23 on the side of the anti-sealing space increase toward the side opposite to the lip edge 21. Relative to the second threaded ridge 25 in the space-side conical surface 23 On the sealed space B side, a boat bottom shape that extends in the opposite direction to the second threaded ridge 25 and has a raised height and width from the anti-sealed space side conical surface 23 toward the opposite side of the lip edge 21. A fourth threaded ridge 27 having a raised shape is formed.

  The first threaded ridge 24 and the second threaded ridge 25 have a cross section perpendicular to each extending direction, and extend at a symmetric inclination angle with respect to each other. Compared to the maximum raised height of the threaded ridge 26 and the fourth threaded ridge 27, the height is sufficiently small. 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. For this reason, when the rotating shaft 200 is rotating in the direction of arrow R in FIG. 2, the sealing target oil in which the first screw protrusion 24 leaks out the sliding portion S with the outer peripheral surface 200 a of the rotating shaft 200. As shown by an arrow F1 in FIG. 2, a forward screw pump action is pushed back to the sliding portion S side, and when the rotation direction is opposite to the arrow R, the sliding portion S leaks out. The forward thread pump action is caused to cause the second thread protrusion 25 to push the oil to be sealed back to the sliding portion S side.

  The end on the lip edge 21 side of the third screw ridge 26 faces the direction intersecting the side surface of the first screw ridge 24, and the end on the lip edge 21 side of the fourth screw ridge 27 is the second screw. It faces the direction intersecting the side surface of the ridge 25. The third screw protrusions 26 and the fourth screw protrusions 27 are provided alternately in the circumferential direction with a plurality of threads as a set. For this reason, when the rotating shaft 200 is rotating in the direction of arrow R in FIG. 2, the fourth screw protrusion 27 causes a forward screw pump action to send the oil to be sealed to the sliding portion S side. When the rotation direction is opposite to the direction of the arrow R, the third screw protrusion 26 causes a forward screw pump action to send the oil to be sealed to the sliding portion S side.

  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, so that a slight gap δ is formed between the outer peripheral surface 200 a of the rotating shaft 200. The gap δ is negative pressure due to the forward screw pump action generated in one of the screw ridges 24 to 27 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. Is to prevent.

  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 edge 21 in the seal lip 2.

  In the sealing device having the above configuration, the fixed seal portion 4 is press-fitted 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 edge 21 in 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. When the lip edge 21 wears in a small amount during initial use, the inner surface of the seal lip 2 is opposite from the sliding portion S with the outer peripheral surface 200a of the rotary shaft 200. On the sealed space B side, out of the first screw ridge 24 and the second screw ridge 25 formed on the conical surface 23 on the anti-sealed space side, the first screw ridge 24 is a forward screw pump action in the R direction, that is, As shown by the broken line arrow F1, a screw pump action for feeding the fluid co-rotating in the R direction to the sliding portion S side is caused. For this reason, even if a part of the sealing target oil existing in the sealed space A passes through the lip edge 21 and the sliding portion S of the rotating shaft 200 and leaks to the anti-sealed space B side, The protrusion 24 is pushed back to the sliding portion S side by the forward screw pump action.

  On the other hand, the second threaded ridge 25 is the anti-sealed space B as shown by the broken arrow F2 in FIG. Invoke the screw pump action to scrape to the side. However, such a reverse screw pump action is smaller than the forward screw pump action of the first screw ridge 24. This is because the forward screw pumping action occurs in the direction of constricting the fluid to the lip edge 21 side (sliding portion S side) like a wedge, whereas the reverse screw pumping action occurs in the diffusion direction. Therefore, as a whole, the forward screw pump action of the first screw ridge 24 is dominant and effectively acts on the seal.

  In addition, the oil to be sealed scraped out from the sliding portion S by the reverse screw pump action of the second screw ridge 25 is the fourth screw ridge located relatively to the anti-sealing space B side from the second screw ridge 25. Since it is pushed back to the sliding portion S side by the forward screw pump action of the strip 27, leakage due to the reverse screw pump action of the second screw protrusion 25 can be effectively reduced.

  As the first screw ridge and the second screw ridge are worn along with the lip edge 21, the screw pump action by the first screw ridge and the second screw ridge is reduced, whereas the third screw ridge and the second screw ridge are reduced. The screw pump action by the four screw ridges increases. FIG. 3 shows a state in which the first screw protrusion and the second screw protrusion disappear due to the progress of wear of the seal lip 2, that is, in this state, the seal lip 2 passes through the sliding portion S from the sealed space A. The oil to be sealed that is about to leak to the anti-sealing space B side is the sliding portion S side by the forward screw pump action of the fourth screw protrusion 27 with respect to the rotation of the rotating shaft 200 in the R direction as indicated by the broken arrow F3. Pushed back. In addition, since the raised height of the fourth screw protrusion 27 increases toward the side opposite to the sliding portion S, the contact length with the rotating shaft 200 is increased, and thus the required forward screw pump action is maintained.

  On the other hand, the third screw protrusion 26 is a reverse screw pump action with respect to the rotation R direction of the rotary shaft 200, that is, a screw pump that scrapes the oil film of the sliding portion S toward the anti-sealing space B as shown by the broken line arrow F4. Invoke action. However, such a reverse screw pump action is smaller than the forward screw pump action of the fourth screw protrusion 27. This is because, as described above, the forward screw pump action occurs in the direction in which the fluid converges to the sliding portion S side like a wedge, whereas the reverse screw pump action occurs in the diffusion direction. Therefore, as a whole, the forward screw pump action of the fourth screw ridge 27 is dominant, and acts effectively on the seal.

  When the rotary shaft 200 rotates in the direction opposite to the R direction, the second screw protrusion 25 acts as a forward screw pump when the lip edge 21 is worn at the initial use, contrary to the above. That is, a screw pumping action that feeds the co-rotating fluid to the sealed space A side and a first screw projection 24 reverse screw pumping action, that is, a screw pump action that scrapes the co-rotating fluid to the anti-sealing space B side. In the state in which the first screw protrusion and the second screw protrusion disappear due to the progress of wear of the seal lip 2, the third screw protrusion 26 acts as a forward screw pump, that is, the co-rotating fluid is sealed in the sealed space. In addition to inducing a screw pumping action to send out to the A side, the fourth screw protrusion 27 causes a reverse screw pumping action, that is, a screw pumping action to scrape the co-rotating fluid to the anti-sealing space B side.

  Therefore, regardless of the rotation direction of the rotating shaft 200, leakage of the oil to be sealed to the anti-sealing space B side is effectively prevented, and excellent sealing performance can be ensured over a long period of time.

DESCRIPTION OF SYMBOLS 1 Reinforcement ring 2 Seal lip 21 Lip edge 23 Anti-sealing space side conical surface 24 First screw protrusion 25 Second screw protrusion 26 Third screw protrusion 27 Fourth screw protrusion 200 Rotating shaft (Rotating body)
A Sealing space B Anti-sealing space S Sliding part

Claims (2)

A seal lip having an outer peripheral surface slidably brought into close contact with the lip edge of the rotating body,
An anti-sealing space side conical surface having a large diameter from the lip edge toward the anti-sealing space side ;
With
In the sliding region near the lip edge in the conical surface on the anti-sealing space side,
A first threaded ridge extending from the lip edge in a constant direction with respect to the circumferential direction and having a substantially elevated height from the conical surface on the anti-sealing space side;
A second threaded ridge extending from the lip edge in a direction opposite to the first threaded ridge and having a raised height from the conical surface on the anti-sealing space side being substantially constant ;
Is provided,
Wherein the anti-seal space side than the first screw projection in the anti-seal space side conical surface, so as to face an end portion on the first screw projection, extends inclined to the first screw projection in the opposite direction A third threaded ridge is provided in which the raised height from the conical surface on the side of the anti-sealing space increases toward the opposite side of the lip edge ;
The end of the second screw ridge is opposed to the second screw ridge on the side opposite to the second screw ridge on the conical surface of the anti- sealing space, and the second screw ridge is inclined in the opposite direction. A fourth threaded ridge is provided in which the raised height from the conical surface on the side of the anti-sealing space increases toward the side opposite to the lip edge ;
A sealing device characterized by that. The first protrusion and the third protrusion correspond one-to-one,
The second protrusion and the fourth protrusion correspond one-to-one.
The sealing device according to claim 1.

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