JP2014092244A - Sealing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent dusts fed from an anti-sealing space side by a screw projection 24 formed on an anti-sealing space side conical face 23 of a seal lip 2 from being accumulated in the anti-sealing space side of a close contact area of a lip edge part 21 and caught in the close contact region.SOLUTION: A sealing device is provided with a seal lip 2 extending toward a close contact space side, and a lip edge part 21 that is slidably in close contact with an outer periphery of a rotation body, and an anti-sealing space side conical face 23 whose diameter gets larger toward the anti-sealing space side from the lip edge part 21 are formed on an inner periphery of the seal lip 2. Plural screw projections 24 for generating a screw pump action toward the lip edge part 21 are formed on the anti-sealing space side conical face 23 by rotating the rotation body in a constant direction. A notch 25 for splitting the screw projection 24 into a screw part 24a on the lip edge part 21 side and a screw part 24b on the anti-sealing space side is formed on each screw projection 24. Axial positions of the notches 25 of the screw projections 24 adjacent to each other in a circumferential direction are different from each other.

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 device in which a screw ridge is formed on the seal lip.

  FIG. 5 is a partial cross-sectional view showing an example of a sealing device according to the prior art in which a screw ridge for obtaining a sealing performance by a screw pump action is formed on a seal lip, together with a partial development view of an inner peripheral surface of the seal lip. 6 is a partial cross-sectional view shown together with a partial development view of a close contact region of the seal lip in the mounted state.

  A sealing device 100 shown in FIG. 5 includes a seal lip 110 formed of a rubber-like elastic material (rubber material or synthetic resin material having rubber-like elasticity), and the inner diameter of the seal lip 110 has the smallest diameter. The sealing space side conical surface 112 having a large diameter toward the sealed space (inside the machine) A side and the anti-sealing space having a large diameter toward the anti-sealed space (atmosphere) B side from the lip edge portion 111 of the A side conical surface 113 is formed, and a plurality of screw protrusions 114 extending at a predetermined inclination angle with respect to the circumferential direction are formed on the anti-sealed space side conical surface 113. Each screw protrusion 114 has a boat bottom shape that gradually changes so that the height and width become maximum in the middle portion in the longitudinal direction, and the tip is continuous or close to the lip edge portion 111. In addition, a garter spring 120 for compensating the tightening force is attached to the outer peripheral portion of the seal lip 110.

  In the sealing state shown in FIG. 6, the sealing device 100 is formed such that a close region (lip line) S of the lip edge portion 111 with respect to the outer peripheral surface of the rotating shaft 200 is continuously formed in the circumferential direction. The entire circumference of the edge portion 111 is slidably brought into close contact with the outer peripheral surface of the rotary shaft 200, thereby preventing the oil to be sealed in the sealed space A from leaking from the shaft circumference to the anti-sealed space B side. is there. In particular, the screw ridges 114, 114,... Cause a screw pump action with the rotation of the rotary shaft 200, that is, the oil to be sealed that leaks the shaft circumference to the anti-sealed space B side is sealed space A. Since it exerts the action of pushing back to the side, it exhibits excellent sealing performance (see, for example, the following prior art document).

Japanese Patent Laid-Open No. 10-19136 JP 7-55014 A

  However, as shown in FIG. 6, in an initial state in which the wear of the lip edge portion 111 in the seal lip 110 is small, the seal lip 110 passes through the tight contact region S between the outer peripheral surface of the rotary shaft 200 and the lip edge portion 111 from the sealed space A and is anti-sealed. It is only the vicinity of the tip 114a of the screw ridge 114 that is in contact with the outer peripheral surface of the rotating shaft 200 that exerts the action of pushing back the oil to be sealed, which is about to leak into the space B, to the sealed space A. The portion 114b other than the vicinity of the tip 114a of the strip 114 is not in contact with the outer peripheral surface of the rotating shaft 200, and there is no oil to be sealed in this portion 114b. However, this portion 114 b has an action of sending dust d such as solid particles from the anti-sealing space B side to the close region S side of the lip edge portion 111.

  For this reason, the dust d sent from the anti-sealing space B side is dammed up near the tip 114a of the threaded ridge 114 and accumulates on the anti-sealing space B side of the close region S of the lip edge portion 111, and a part thereof May be bitten in the close region S and may reduce the sealing performance.

  The present invention has been made in view of the above points, and its technical problem is that the screw ridge formed on the conical surface on the anti-sealing space side of the seal lip from the anti-sealing space side. The purpose is to prevent the dust that has been sent from accumulating on the anti-sealing space side of the lip edge and biting into the close area of the lip edge.

  As a means for effectively solving the technical problem described above, a sealing device according to the invention of claim 1 includes a seal lip extending toward the sealed space side, and an inner peripheral surface of the seal lip is provided with a rotating body. A lip edge portion slidably in contact with the outer peripheral surface, and an anti-sealing space side conical surface having a large diameter from the lip edge portion toward the anti-sealing space side are formed. When the rotating body rotates in a certain direction, a plurality of screw ridges that generate a screw pump action toward the lip edge portion side are formed, and each screw ridge is attached to the lip edge portion side. A notch that is divided into a threaded portion and a threaded portion on the anti-sealing space side is formed, and the axial positions of the notches of the threaded ridges adjacent in the circumferential direction are different from each other.

  According to a second aspect of the present invention, in the configuration of the first aspect, the sealing device is formed on a screw ridge relatively positioned on the rotational direction side of the rotating body among the screw ridges adjacent in the circumferential direction. The notch is located on the side opposite to the sealed space with respect to the notch formed in the screw protrusion relatively positioned on the opposite side to the rotation direction of the rotating body.

  According to the sealing device of the present invention, a part of the dust sent from the anti-sealing space side to the lip edge side by the screw pump action of the screw ridge is discharged through the notch formed in the screw ridge. Therefore, dust can be prevented from accumulating on the anti-sealing space side of the lip edge part, and even if the threaded ridge is worn from the lip edge part side due to wear of the lip edge part, By forming the notches at different axial positions, the screw seal effect by the screw ridges and the dust discharge effect by the notches are maintained, and as a result, the accumulated dust is bitten into the close area of the lip edge part. The deterioration of the sealing performance due to is prevented.

It is a fragmentary sectional view which shows preferable embodiment of the sealing device which concerns on this invention with the partial expanded view of the internal peripheral surface of a seal lip. In preferred embodiment of the sealing device which concerns on this invention, it is explanatory drawing which shows the axial direction positional relationship of the notch formed in the screw protrusion. It is a fragmentary sectional view of the mounting state which shows preferable embodiment of the sealing device which concerns on this invention. It is explanatory drawing which shows the effect | action by the notch formed in the screw protrusion in preferable embodiment of the sealing device which concerns on this invention. It is a fragmentary sectional view which shows an example of the sealing device by a prior art with the partial expanded view of the internal peripheral surface of a seal lip. It is a fragmentary sectional view which shows the sealing device of FIG. 5 with the partial expanded view of the close_contact | adherence area | region of the seal lip in a mounting state.

  Hereinafter, a preferred embodiment of a sealing device according to the present invention will be described with reference to FIGS.

  That is, in the sealing device according to this embodiment, as shown in FIGS. 1 and 3, a seal lip 2 made of a rubber-like elastic material (rubber material or a synthetic resin material having rubber-like elasticity) is formed on a metal reinforcing ring 1. The dust lip 3 is integrally formed. A garter spring 4 is mounted on the outer peripheral surface near the tip of the seal lip 2.

  The seal lip 2 extends from the inner diameter end of the reinforcing ring 1 in the direction of the sealed space A in the mounted state shown in FIG. 3, and is slidable with the outer peripheral surface 200a of the rotary shaft 200 on the inner periphery near the tip. A lip edge portion 21 having a mountain-shaped cross section in close contact with each other, a sealed space side conical surface 22 having a large diameter toward the sealed space A side from the lip edge portion 21, and an anti-sealed space B side An anti-sealed space side conical surface 23 having a large diameter is formed. The rotating shaft 200 corresponds to the rotating body described in claim 1.

  A plurality of threaded ridges 24, 24,... Whose tip ends reach the lip edge portion 21 are formed on the anti-sealing space side conical surface 23 of the seal lip 2 at a predetermined pitch in the circumferential direction. As shown in FIG. 2, the screw ridges 24, 24,... Extend at a predetermined inclination angle α in the rotation direction (R direction) of the rotation shaft. As the outer peripheral surface 200a moves in the R direction by the rotation, it causes a screw pump action that feeds the fluid that is dragged together with the outer peripheral surface 200a of the rotating shaft 200 to the lip edge portion 21 side. is there.

  Specifically, each thread protrusion 24 has a tip portion, that is, a portion in the vicinity of the lip edge portion 21, in which the cross section perpendicular to the extending direction forms a mountain shape, and the height and width of the protrusion from the conical surface 23 on the anti-sealing space side The bottom of the boat has a small shape, and the portion from the position slightly away from the lip edge portion 21 to the end portion on the anti-sealing space side gradually increases while drawing a gentle arc toward the anti-sealing space side. I am doing. And the ridge part of the part which makes the boat bottom shape in the screw protrusion 24 is non-contact with respect to the outer peripheral surface 200a of the rotating shaft 200 in the initial mounting state, and the gap between the two is opposite to the lip edge part 21 ( The larger the anti-sealing space B side).

  Each screw ridge 24 is formed with a notch 25 that divides the screw ridge 24 into a screw portion 24a on the lip edge portion 21 side and a screw portion 24b on the anti-sealing space B side. The bottom surface of the notch 25 is flush with the anti-sealed space side conical surface 23.

  As shown in FIG. 2, the notch 25 extends in the extending direction (circumferential direction) of the lip edge portion 21, and the shafts of the notches 25, 25 formed in the threaded ridges 24, 24 adjacent in the circumferential direction. The direction positions are different from each other, and the notches 25 and 25 adjacent in the circumferential direction partially overlap in the axial direction as indicated by reference numeral δ. Specifically, the notch 25 formed in the screw protrusion 24 positioned relatively on the rotation direction (R direction) side of the rotation shaft among the screw protrusions 24 and 24 adjacent in the circumferential direction is relatively R It is located on the anti-sealing space B side with respect to the notch 25 formed in the screw protrusion 24 located on the opposite side to the direction. Therefore, as shown also in FIG. 1, the notches 24, 24,... Are formed so as to gradually move away from the lip edge portion 21 in the rotation direction (R direction) of the rotation shaft.

  The garter spring 4 is formed by connecting metal coil springs in an annular shape, and is fitted in an annular groove 26 formed on the outer peripheral surface of the seal lip 2 near the tip.

  The sealing device configured as described above is press-fitted to the inner peripheral surface of a housing (not shown) so that the seal lip 2 faces the sealed space A side, and the lip edge portion 21 of the seal lip 2 is shown in FIG. The oil to be sealed 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 shown in FIG.

  A part of the oil to be sealed existing in the sealed space A intervenes in the close region S between the lip edge 21 of the seal lip 2 and the outer peripheral surface 200a of the rotary shaft 200. Even if it passes and leaks to the anti-sealing space B side, this oil is caused by the screw pump action formed on the screw ridges 24, 24, ... formed on the anti-sealing space side conical surface 23 of the seal lip 2. It is pushed back to the close area S side. This is because when the outer peripheral surface 200a moves in the R direction in FIG. 2 due to the rotation of the rotating shaft 200, the oil to be sealed that is present in the vicinity of the close contact region S is also dragged by the outer peripheral surface 200a of the rotating shaft 200 in the R direction. In order to rotate, a screw pump that feeds the oil to be sealed that is rotating in the R direction in the vicinity of the tip of each screw protrusion 24 that is in close contact with the outer peripheral surface 200a of the rotating shaft 200 to the lip edge 21 side. Invoke action. For this reason, leakage of the oil to be sealed is effectively prevented, and a lubricating oil film made of the oil to be sealed is formed in the intimate region S to ensure good lubricity.

On the other hand, at a position slightly away from the close region S of the lip edge 21 toward the anti-sealing space B, there is no oil to be sealed on the outer periphery of the rotating shaft 200, and the flange portion of the screw protrusion 24 is the outer peripheral surface of the rotating shaft 200. 200a is non-contact, and the gap between the two is larger toward the anti-sealing space B side, so the screw pump function is weak, but the flange portion of the screw protrusion 24 and the outer peripheral surface of the rotary shaft 200 large dust particle size than the clearance between the 200a is captured by the screw ridge 24, as shown at d ₁ in FIG. 2, it is fed to the lip edge portion 21 side.

However, some d ₂ of the dust is sent to the lip edge portion 21 side by the screw ridge 24, it flows to the circumferential direction through a cutout 25 formed to the screw ridge 24, opposite to the sealed space by the centrifugal force It is discharged to the large diameter side (anti-sealed space B side) of the side conical surface 23. The notches 25 and 25 adjacent in the circumferential direction, since it is arranged such that a portion overlapping in the axial direction, the flow of dust d ₂ to such circumferential direction is generated smoothly. Some d ₃ of the dust passing through the notch 25 is to be sent is captured on the threaded portion 24a of the lip edge part 21 side in the circumferential direction next to the screw ridge 24 to the lip edge portion 21 side The amount is reduced by the discharging action by the notch 25.

  For this reason, it suppresses that dust accumulates in the anti-sealing space B side of the close_contact | adherence area | region S of the lip edge part 21, and also prevents the fall of the sealing performance by the accumulated dust being bitten by the said close_contact | adherence area | region S. be able to.

Further, as the lip edge portion 21 wears, the close contact area S with the outer peripheral surface 200a of the rotating shaft 200 spreads as shown in FIG. I wear out. Then, for example, as the leftmost screw ridges 24 ₁ in FIG. 4, when the cutout 25 than as screw portion 24a of the lip edge portion 21 side is fully worn, the screw pumping action is lost in this part However, since the screw ridges 24 ₂ , 24 ₃ ,... On the right side thereof have the screw portion 24a on the lip edge portion 21 side, the screw pump action as a whole is not impaired.

Then, for example, the leftmost dust which has been deposited on the tip of the screw ridges 24 ₁ in FIG. 4, with the wear of the tip of the screw ridges 24 _1, gradually circumferentially adjacent the notch 25 screw moves to ridge 24 ₂ of the front end portion, but as a part of which shown at d _4, flows to the circumferential direction through a plurality of notches 25, as described above, opposite to the sealed space side cone It is discharged to the large diameter side (anti-sealed space B side) of the surface 23.

  And by these effects | actions, the fall of the sealing performance by the accumulated dust biting into the close_contact | adherence area | region S is prevented effectively.

2 Seal lip 21 Lip edge part 23 Anti-sealing space side conical surface 24 Screw protrusion 24a Screw part 24b on the lip edge part 21 side Screw part 25 on the anti-sealing space B side Notch 200 Rotating shaft (rotating body)
A Sealed space B Anti-sealed space S Close area

Claims (2)

  A seal lip extending toward the sealed space side is provided, and a lip edge portion slidably in contact with the outer peripheral surface of the rotating body is provided on the inner peripheral surface of the seal lip, and the lip edge portion is directed to the anti-sealed space side. A conical surface on the anti-sealing space side having a large diameter is formed, and a plurality of screw pumping actions are generated on the anti-sealing space side conical surface toward the lip edge portion side by rotating the rotating body in a certain direction. A screw protrusion is formed, and a notch for dividing the screw protrusion into a screw portion on the lip edge portion side and a screw portion on the anti-sealing space side is formed in each screw protrusion, and the screw protrusions adjacent in the circumferential direction are formed. A sealing device characterized in that the axial positions of the notches of the strips are different from each other.   Among the thread ridges adjacent to each other in the circumferential direction, the thread ridge in which the notch formed in the screw ridge relatively positioned on the rotational direction side of the rotating body is relatively positioned on the opposite side to the rotational direction of the rotating body. 2. The sealing device according to claim 1, wherein the sealing device is located on a side opposite to the sealed space with respect to a notch formed in the strip.

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