JP4702517B2 - Oil seal - Google Patents

Description

  The present invention relates to an oil seal which is a kind of a sealing device, and more particularly to an oil seal in which a bidirectional screw rib is provided on a sliding portion of a seal lip. The oil seal of the present invention is used for sealing oil in a bearing, for example.

  2. Description of the Related Art Conventionally, an oil seal having a screw rib that performs a fluid pumping action on a sliding portion of a seal lip in order to improve sealing performance against a sealing fluid such as oil has been known. In the case where the shaft (hereinafter simply referred to as a shaft) rotates in both the forward and reverse directions, a bidirectional screw rib 52 is provided on the sliding portion 51a of the seal lip 51 as shown in FIG.

  This bi-directional screw rib 52 has several forward screw ribs 53 that perform a sealing action by pumping when the shaft rotates in the forward direction and several reverse screw ribs 54 that perform a sealing action by pumping when the shaft rotates in the reverse direction. Each of the screw ribs 53 and 54 has a triangular cross section as shown in enlarged views in FIGS. 8A and 8B. And have pointed tips 53a and 54a.

  When the contact line CL with respect to the axis of the bi-directional screw rib 52 is observed, it is as shown in FIG. 9, and the reverse screw rib 54 on the right side of the drawing is a local gap at the back side portion (the portion on the positive rotation direction side of the shaft) 54b. (Small gaps) and stress reduction occurs. Therefore, when the forward rotational speed of the shaft is increased, oil leakage (splash leakage) occurs at the rear portion 54b of the reverse screw rib 54 (arrow B), and the leaked oil is scraped by the tip 54a of the reverse screw rib 54. Since it is put out (arrow C), there is an inconvenience that oil leakage is increased and sealing performance is lowered.

  In addition, although the front side part (part on the reverse rotation direction side of the shaft) 53b of the forward direction screw rib 53 is also in the same contact state, the fluid scraping is not in the leakage direction, and this causes a problem of deterioration in sealing performance. (However, when the shaft rotates in the opposite direction, the same problem occurs on the side of the forward screw rib 53).

  As another prior art for the present application, an oil seal in which a minute round is attached to the tip of the screw rib is shown in FIG. 2 of Japanese Utility Model No. 2555335 (Patent Document 1).

  However, this prior art exclusively defines the size of the apex angle of the screw rib having a triangular cross-section to 120 to 140 degrees, and the cross-sectional shape of the screw rib is positive at the tip of the screw rib as in the present invention. The shape is not round. In actual processing, it is difficult for the screw cutter itself to produce a perfect sharp angle, and when the rubber material is pushed into the mold, it is unavoidable that “sag” occurs and a minute round is attached to the tip of the screw rib. However, FIG. 2 of Patent Document 1 only shows such a minute radius (this radius is formed so that the radius of curvature is smaller than the height of the screw rib). It should be distinguished from the present invention.

No. 2553435 Utility Model Registration Gazette (Fig. 2)

  In view of the above, the present invention can reduce the fluid scraping force generated in the reverse screw rib when the shaft rotates in the forward direction in the oil seal in which the bidirectional screw rib is provided in the sliding portion of the seal lip. An oil seal capable of reducing the fluid scraping force generated in the forward direction screw rib when the shaft rotates in the opposite direction and reducing the amount of fluid leakage and improving the sealing performance. For the purpose.

In order to achieve the above object, an oil seal according to claim 1 of the present invention is an oil seal in which a bidirectional screw rib comprising a combination of a forward screw rib and a reverse screw rib is provided on a sliding portion of a seal lip, and the forward screw rib. Each of the reverse screw ribs is composed of a combination of a parallel screw disposed on the front end side of the seal lip and a ship bottom screw arranged in series on the atmosphere side of the parallel screw. The cross-sectional shape of the parallel screw is rounded at the tip, and a flat portion is formed in the central portion in the width direction of the rounded shape .

An oil seal according to a second aspect of the present invention is the oil seal according to the first aspect, wherein the round shape formed at the tip of the parallel screw has a radius of curvature larger than the height of the parallel screw. It is characterized by being set large.

In the prior art, a relatively large fluid scraping force is generated in the screw ribs 53 and 54 because the screw ribs 53 and 54 have a triangular cross-sectional shape and the pointed tips 53a and 54a are pointed at the screw ribs 53 and 54, respectively. This is considered to be due to the occurrence of the scraper phenomenon due to the sharp edges 53a and 54a. According to the present invention, on the other hand, since the cross-sectional shape of the parallel screw of Nejiribu comprising a combination of parallel screw and the ship bottom screw is Earl shape at its distal end, reduces the scraper phenomenon that occurs Therefore, the fluid scraping force by the screw rib can be reduced accordingly. In addition, as described in claim 2, it is preferable to set the radius of curvature of the round shape larger than the height dimension of the parallel screw . In addition, by providing a flat portion at the central portion in the width direction of the round shape, the contact area with respect to the axis of the parallel screw is expanded and the contact state is stabilized. Therefore, the back side portion of the reverse screw rib and the front side portion of the forward screw rib It is possible to reduce local gaps (minute gaps) and stress reduction itself.

  The present invention has the following effects.

That is, in the oil seal according to claim 1 or 2 of the present invention having the above-described configuration, the cross-sectional shape of the parallel screw of the screw ribs formed by the combination of the parallel screw and the ship bottom screw is rounded at the tip portion. Therefore, the generated scraper phenomenon can be reduced, and accordingly, the fluid scraping force by the screw rib can be reduced accordingly. Therefore, when the shaft rotates in the forward direction, the fluid scraping force generated in the reverse screw rib can be reduced, and when the shaft rotates in the reverse direction, the fluid scraping force generated in the forward screw rib. In any case, the amount of fluid leakage can be reduced and the sealing performance can be improved.

In addition to this, in the oil seal according to claim 1 or 2 of the present invention having the above-described configuration, since a flat portion is provided in the central portion in the width direction of the round shape, the contact area with respect to the shaft of the parallel screw is provided. Is enlarged and the contact state is stabilized, whereby local gaps (minute gaps) and stress reduction itself occurring at the back side portion of the reverse screw rib and the front side portion of the forward screw rib can be reduced. Therefore, it is possible to reduce oil leakage (splash leakage) that occurs at the back side portion of the reverse screw rib and the front side portion of the forward screw rib during high-speed rotation of the shaft, so that the sealing performance is also improved from this point. Can do.

  The present invention includes the following embodiments.

Related to Claims 1 and 2
An oil seal having a bi-directional screw rib in which forward screw ribs and reverse screw ribs are alternately arranged on the circumference of the sliding portion of the main lip. sticker. Both side portions (bottom portions) of the thread tip portion having a rounded cross-sectional shape are linear in cross section, but may be curved in cross section.

(1) As a measure against splash leakage, the tip of the thread is rounded (parallel screw). Further, in order to improve durability against lip wear and shaft wear, a combination of a parallel screw and a ship bottom screw is adopted.
(2) By making the thread tip into a round shape, the contact area is increased, the generation of a minute gap between the lip tip and the thread is suppressed, and the contact state with the shaft is made continuous and linear. . If necessary, a flat portion is formed in the central portion in the width direction of the round shape. Both side portions (bottom portions) of the thread tip having a rounded cross section may be linear in cross section or curved in cross section.

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

First embodiment ...
FIG. 1 shows a cross section of the main part of an oil seal 1 according to a first embodiment of the present invention. 2A shows an enlarged cross-sectional view of the main part of the oil seal 1, and FIG. 2B shows an enlarged cross-sectional view taken along the line DD in FIG. 2A.

  As shown in FIG. 1, an oil seal 1 according to this embodiment has a seal lip 2 made of rubber-like elastic material bonded to a metal ring 3 by vulcanization. Bidirectional screw ribs indicated by reference numeral 5 as a whole are provided on the sliding surface 2a which is slidably in close contact with the peripheral surface, and on the atmosphere-side inclined surface 2b.

  The bidirectional screw rib 5 includes a forward screw rib 6 that performs a sealing action by pumping when the shaft 4 rotates in the forward direction, and a reverse screw rib 7 that performs a sealing action by pumping when the shaft 4 rotates in the reverse direction. It consists of a combination, and both screw ribs 6 and 7 are alternately arranged on the circumference every several to several tens. Both screw ribs 6 and 7 are provided so as to incline in directions opposite to each other, and are respectively provided so as to reach the tip top 2c of the seal lip 2 and intersect the tip top 2c.

  As shown in an enlarged view in FIG. 2 (B), each of the screw ribs 6, 7 has a cross-sectional shape (a cross-sectional shape in a direction perpendicular to the longitudinal direction of each screw rib 6, 7) based on a triangle. The front end portion is rounded and formed into a round shape 6a, 7a having a circular arc cross section. The screw ribs 6 and 7 are not formed with sharp tips as in the above prior art, and the rounded shapes 6a and 7a having a size larger than that of the fine round as in the above-mentioned Patent Document 1 are formed. Therefore, it is not formed. In addition, since the said micro round is generally a magnitude | size of less than R0.01mm, if the round shape 6a, 7a which concerns on this invention is specified numerically, the magnitude | size will be R0.01mm or more, R0.02 mm or more from the viewpoint of more clearly discriminating the difference between them (in the past, a minute radius of about R0.01 mm may be attached due to processing, but the present invention achieves the intended purpose. In addition, a radius of R 0.02 mm or more is actively provided).

Also, the when describing the magnitude of the radius from the comparison of the height h ₂ of Nejiribu 6,7, micro Earl according to Patent Document 1 has a radius of curvature has been formed smaller than the height dimension of the Nejiribu respect, in this embodiment, is set larger than the radius shape 6a, the height h ₂ of the curvature radius R Nejiribu 6,7 7a.

  The contact line CL itself with respect to the shaft 4 of the oil seal 1 having the above-described configuration is the same as that in FIG. 9, and a small amount of oil leaks (arrow B However, since the cross-sectional shape of the screw rib 7 is the round shape 7a at the tip of the screw rib 7, the scraper phenomenon that occurs can be reduced. It is possible to reduce the fluid scraping force. Therefore, the amount of fluid leakage can be reduced, and the sealing performance can be improved. Further, when the shaft 4 rotates in the reverse direction, the same phenomenon occurs in the forward direction screw rib 6, and thus the same effect is exhibited.

In addition, since this inventor performed the performance comparison test of the said oil seal 1, the content and result are demonstrated below.
Contents of Example Products (1) Rubber material of the oil seal 1: Fluorine rubber (2) Angle θ _{1 of the} screw ribs 6 and 7 with respect to the seal lip tip apex 2c: 20 degrees (3) Width w of the screw ribs 6 and 7: 0 .10mm
(4) Apex angle θ _{2 of the} screw ribs 6 and 7: 120 degrees (5) Height of the screw ribs 6 and 7 before the formation of the round shapes 6a and 7a (the height of the basic triangle) h ₁ : 0.029 mm
(6) Curvature radius R of round shape 6a, 7a: 0.06mm
(7) Height h ₂ of the screw ribs 6 and 7 after forming the round shapes 6a and 7a: 0.02 mm
Contents of Comparative Example Product (6) Curvature radius R of round shapes 6a and 7a: less than 0.01 mm The above (1) to (5) are the same as the example product
Test conditions (A) Shaft diameter: 170 mm
(B) Number of rotations: 1850 rpm (forward rotation, reverse rotation)
(C) Sealing fluid: Turbine oil (D) Test temperature: 100 ° C
(E) Test time: 20h
Results While the test result of the comparative example product was “with splash leakage”, the example product was “no leak”, and thus the effect of the present invention could be confirmed.

Second embodiment ...
FIG. 3 shows a cross section of the main part of the oil seal 1 according to the second embodiment of the present invention. 4 shows an enlarged cross-sectional view of the main part of the oil seal 1, and FIG. 5 shows an enlarged cross-sectional view taken along line EE in FIG.

  As shown in FIG. 3, the oil seal 1 according to this embodiment has a seal lip 2 made of rubber-like elastic material that is vulcanized and bonded to a metal ring 3. Bidirectional screw ribs indicated by reference numeral 5 as a whole are provided on the sliding surface 2a which is slidably in close contact with the peripheral surface, and on the atmosphere-side inclined surface 2b.

  The bidirectional screw rib 5 includes a forward screw rib 6 that performs a sealing action by pumping when the shaft 4 rotates in the forward direction, and a reverse screw rib 7 that performs a sealing action by pumping when the shaft 4 rotates in the reverse direction. It consists of a combination, and both screw ribs 6 and 7 are alternately arranged on the circumference every several to several tens. Both screw ribs 6 and 7 are provided so as to incline in directions opposite to each other, and are respectively provided so as to reach the tip top 2c of the seal lip 2 and intersect the tip top 2c.

As shown in an enlarged view in FIG. 4, the forward screw rib 6 includes a parallel screw 8 disposed on the tip top 2 c side of the seal lip 2 and a bottom screw 9 disposed in series on the atmosphere side of the parallel screw 8. Of which the cross-sectional shape of the parallel screw 8 (the cross-sectional shape in the direction orthogonal to the longitudinal direction of the parallel screw 8) is rounded at the tip as shown in FIG. The round shape 8a is formed. Further, the contact area relative to the axis 4 in the width direction central portion of the rounded shape 8a, the flat part 8b having a predetermined width w ₁ consisting a straight line parallel section and the air-side slope 2b is formed, thereby Has been realized.

Further, as shown in an enlarged view in FIG. 4, the reverse screw rib 7 is similarly arranged in series on the parallel screw 10 arranged on the tip top 2 c side of the seal lip 2 and on the atmosphere side of the parallel screw 10. The cross-sectional shape of the parallel screw 10 (the cross-sectional shape in a direction perpendicular to the longitudinal direction of the parallel screw 10) is rounded at the tip as shown in FIG. The round shape 10a has a circular arc shape in cross section. Further, the contact area relative to the axis 4 in the width direction central portion of the rounded shape 10a, the flat portion 10b having a predetermined width w ₁ consisting a straight line parallel section and the air-side slope 2b is formed, thereby Has been realized.

  The parallel screws 8 and 10 mean that the screw shape is formed by two parallel lines 8c, 8c, 10c and 10c when the surface of the atmosphere side inclined surface 2b of the seal lip 2 is viewed (cross-sectional shape). Does not matter). Further, the ship bottom screws 9 and 11 have a ship bottom shape as the name suggests, and are formed in such a shape that the cross-sectional shape gradually increases and decreases along the longitudinal direction. The cross-sectional shape of the ship bottom screws 9 and 11 is generally triangular, and has ridge line portions 9a and 11a and slope portions 9b and 11b on both sides thereof.

  The contact line CL for the shaft 4 of the oil seal 1 having the above configuration is as shown in FIG. 6 and, as can be seen from the comparison with FIG. Local gaps (minute gaps) generated in the front portion of the screw rib 6 and stress reduction itself are reduced (the recesses forming the local gaps (minute gaps) have disappeared). Therefore, oil leakage (splash leakage) occurring at the back side portion of the reverse screw rib 7 and the front side portion of the forward screw rib 6 during high-speed rotation of the shaft 4 can be reduced, so that the sealing performance can be improved. it can.

  Further, the screw ribs 6 and 7 formed by combining the parallel screws 8 and 10 and the ship bottom screws 9 and 11 have an advantage that durability against lip wear and shaft wear can be improved.

Sectional drawing of the principal part of the oil seal which concerns on 1st Example of this invention. 2A is an enlarged cross-sectional view of the main part of the oil seal, and FIG. 2B is an enlarged cross-sectional view taken along the line DD in FIG. 2A. Sectional drawing of the principal part of the oil seal which concerns on 2nd Example of this invention. The main part enlarged sectional view of the oil seal EE expanded sectional view in FIG. Explanatory drawing showing the contact line for the shaft of the oil seal Half cut sectional view of oil seal according to conventional example 8A is an enlarged cross-sectional view of the main part of the oil seal, and FIG. 8B is an enlarged cross-sectional view taken along line AA in FIG. 8A. Explanatory drawing showing the contact line for the shaft of the oil seal

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Oil seal 2 Seal lip 2a Sliding part 2b Atmosphere side slope 2c Tip top part 3 Metal ring 4 Axis 5 Both direction screw rib 6 Forward direction screw rib 6a, 7a, 8a, 10a Earl shape 7 Reverse direction screw rib 8, 10 Parallel screw 8b, 10b Flat part 8c, 10c Parallel line 9, 11 Ship bottom screw 9a, 11a Ridge part 9b, 11b Slope part

Claims (2)

In an oil seal in which a bidirectional screw rib composed of a combination of a forward screw rib and a reverse screw rib is provided on the sliding portion of the seal lip,
The forward screw rib and the reverse screw rib are each composed of a combination of a parallel screw arranged on the tip side of the seal lip and a bottom screw arranged in series on the atmosphere side of the parallel screw,
Of the parallel screw and the ship bottom screw, the cross-sectional shape of the parallel screw is rounded at the tip thereof, and a flat portion is formed at the center in the width direction of the rounded shape. . The oil seal of claim 1.
The round shape formed at the tip of the parallel screw has a radius of curvature that is set larger than the height of the parallel screw .

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