WO2020196170A1

WO2020196170A1 - Bearing with seal

Info

Publication number: WO2020196170A1
Application number: PCT/JP2020/012035
Authority: WO
Inventors: 中尾　吾朗
Original assignee: Ntn株式会社
Priority date: 2019-03-25
Filing date: 2020-03-18
Publication date: 2020-10-01
Also published as: JP2020159382A

Abstract

A sealing lip (10) has: a circumferential protuberance (15) extending continuously in a circumferential direction without interruption throughout the entire circumference of a seal sliding contact surface (14) so as to tightly seal an annular space (4) by being in contact with the entire circumference; and a plurality of axial protuberances (16) that extend from an axial side surface of the circumferential protuberance (15) along the sliding contact surface (14) at the same height as the circumferential protuberance (15) or lower, and that are formed at a constant pitch in the circumferential direction.

Description

Bearing with seal

The present invention relates to a bearing with a seal in which a seal member is provided between the inner ring and the outer ring.

Generally, rolling bearings are used for rotating parts of automobiles and industrial machines. The rolling bearing has an inner ring, an outer ring coaxially provided on the radial outer side of the inner ring, and a plurality of rolling elements provided in an annular space between the inner ring and the outer ring.

Here, it is formed between the inner ring and the outer ring in order to prevent foreign matter from entering the inside from the outside of the rolling bearing and to prevent the lubricant from leaking from the outside to the outside of the rolling bearing. Sealed bearings may be used in which the end opening of the annular space is closed with an annular sealing member. The seal member has a seal lip that is in sliding contact with the seal sliding contact surface formed on the inner ring or the outer ring in the circumferential direction, and the contact between the seal lip and the seal sliding contact surface prevents foreign matter from entering and lubricant leakage. (Patent Documents 1 to 4).

Japanese Unexamined Patent Publication No. 2018-021632 JP-A-2007-107588 Japanese Unexamined Patent Publication No. 2017-155818 Japanese Unexamined Patent Publication No. 2017-032051

When using this bearing with a seal, the seal lip of the seal member is in contact with the seal sliding contact surface, so that a seal torque (rotational resistance due to the sliding contact of the seal lip) is generated. Here, the tightening allowance of the seal lip may change depending on the dimensional accuracy of the seal member, the inner ring, the outer ring, the temperature, and the like. If the tightening allowance of the seal lip becomes large, an excessive seal torque or abnormal heat generation of the bearing may occur.

In addition, bearings with seals may cause a seal lip adsorption phenomenon. In the adsorption phenomenon of the seal lip, when the temperature of the bearing rises once and then decreases, a pressure difference is generated between the inside and the outside of the bearing partitioned by the seal member, and the pressure difference causes the seal member to have a pressure difference. This is a phenomenon in which the seal lip sticks to the seal sliding contact surface. Even when this sealing lip adsorption phenomenon occurs, excessive sealing torque and abnormal heat generation of the bearing may occur.

On the other hand, in order to stabilize the seal torque of the bearing with a seal, by softening the waist of the seal lip, measures to suppress the increase in the seal torque when the tightening allowance increases, and the initial wear of the seal lip are used. It is conceivable to take measures such as reducing the tightening allowance of the seal lip to zero.

However, even if any of these measures is taken, it is possible to keep the sealing torque low, but there is a problem that the sealing performance deteriorates accordingly. In other words, there is a trade-off relationship between seal torque and seal performance, in which if one is pursued, the other must be sacrificed. Further, even if any of the above measures is taken, it is difficult to prevent the seal lip from becoming excessive when the seal lip adsorption phenomenon occurs.

Therefore, as a measure to prevent the sticking phenomenon of the seal lip, a slit penetrating in the axial direction is provided at the tip of the seal lip, and the slit is used as an air passage to make the inside and outside of the bearing partitioned by the seal member. It is conceivable to take a method of preventing the occurrence of a pressure difference between the bearing and the bearing.

However, if a slit that serves as an air passage is provided in the seal lip, there is a problem that the seal performance of the seal member deteriorates due to the slit.

The problem to be solved by the present invention is that the seal torque does not easily fluctuate even when the seal lip tightening allowance changes due to dimensional accuracy, temperature change, seal lip adsorption phenomenon, etc., and the seal has high sealing performance. To provide bearings.

In order to solve the above problems, the present invention provides a bearing with a seal having the following configuration.
Inner ring and
An outer ring coaxially provided on the outer side in the radial direction of the inner ring,
A plurality of rolling elements incorporated in an annular space formed between the inner ring and the outer ring,
It has an annular seal member that closes the end opening of the annular space.
In a bearing with a seal having a seal lip in which the seal member has a seal lip that is in sliding contact with a seal sliding contact surface that is continuous in the circumferential direction and is formed on one of the raceway rings of the inner ring and the outer ring.
The seal lip
Circumferential protrusions extending continuously in the circumferential direction without interruption over the entire circumference so as to seal the annular space by contacting the seal sliding contact surface on the entire circumference.
Axial protrusions extending axially from the axial side surface of the circumferential protrusion along the seal sliding contact surface at the same height as or lower than the circumferential protrusion, and a plurality of axial protrusions formed at a constant pitch in the circumferential direction. And, a bearing with a seal characterized by having.

In this way, even when the tightening allowance of the seal lip increases due to dimensional accuracy, temperature change, adhesion phenomenon of the seal lip, etc., an oil film due to the wedge effect between the axial protrusion of the seal lip and the seal sliding contact surface Is formed, and the oil film keeps the frictional resistance between the axial protrusion and the seal sliding contact surface small. Therefore, the seal torque is unlikely to increase even when the tightening allowance of the seal lip increases. Further, since the circumferential protrusions extending continuously in the circumferential direction over the entire circumference come into contact with the sealing sliding contact surface on the entire circumference, it is possible to seal the bearing space with high sealing performance.

It is preferable that the difference between the height of the axial protrusion and the height of the circumferential protrusion is set to less than 0.5 mm.

In this way, when the tightening allowance of the seal lip increases, the axial protrusion slides into contact with the seal sliding contact surface via the oil film to maintain the seal lip posture, and the circumferential protrusion covers the entire circumference of the circumferential protrusion. It is possible to maintain stable contact between the seal and the sliding contact surface.

The seal lip is preferably formed of rubber having a shore hardness of 65 Hs or more.

By doing so, it is possible to secure stable sealing performance even when dimensional accuracy, temperature change, adsorption phenomenon of seal lip, etc. occur.

It is preferable that the axial protrusion adopts an arc-shaped protrusion having an arc-shaped cross section along a surface extending in the circumferential direction orthogonal to the seal sliding contact surface.

In this way, the lubricating oil adhering to the seal sliding contact surface is easily introduced between the seal sliding contact surface and the axial protrusion of the seal lip, so that due to the wedge effect between the axial protrusion and the seal sliding contact surface. It is possible to stably form an oil film.

The circumferential pitch of the axial protrusion is preferably 3.0 mm or less.

In this way, it is possible to stably form an oil film due to the wedge effect between the axial protrusion and the seal sliding contact surface.

The seal sliding contact surface can be a cylindrical surface. In this case, it is possible to provide a garter spring that tightens the seal lip from the outer diameter side.

The bearing with a seal of the present invention has a wedge between the axial protrusion of the seal lip and the sliding contact surface of the seal even when the tightening margin of the seal lip increases due to dimensional accuracy, temperature change, adsorption phenomenon of the seal lip, or the like. An oil film is formed by the effect, and the oil film suppresses the frictional resistance between the axial protrusion and the sealing surface. Therefore, the seal torque is unlikely to increase even when the tightening allowance of the seal lip increases. Further, since the circumferential protrusions extending continuously in the circumferential direction over the entire circumference come into contact with the sealing sliding contact surface on the entire circumference, it is possible to seal the bearing space with high sealing performance.

Sectional drawing which shows the bearing with a seal which concerns on embodiment of this invention. Enlarged sectional view showing the vicinity of the seal lip of FIG. Sectional view taken along the line III-III of FIG. A view of the seal lip of FIG. 2 from the inside in the radial direction. The figure which shows another example of the seal member shown in FIG. A cross-sectional view showing a state in which the bearing with a seal shown in FIG. 1 is used as a rolling bearing that rotatably supports the rotating shaft of an automobile transmission.

FIG. 1 shows a bearing 1 with a seal according to an embodiment of the present invention. The sealed bearing 1 is spaced apart in the circumferential direction in the inner ring 2, the outer ring 3 coaxially provided on the radial outer side of the inner ring 2, and the annular space 4 formed between the inner ring 2 and the outer ring 3. It has a plurality of incorporated balls 5, a cage 6 for holding the distance between the plurality of balls 5 in the circumferential direction, and a pair of sealing members 7 for closing the end openings on both sides of the annular space 4.

The seal member 7 is an annular member formed by vulcanizing and adhering a rubber material 9 (for example, nitrile rubber) to the surface of the annular core metal 8. A rubber seal lip 10 is provided at the inner diameter side end of the seal member 7. The seal lip 10 extends from the inside in the axial direction (the side closer to the ball 5) toward the outside in the axial direction (the side far from the ball 5), and has a tip on the outer side in the axial direction. As the rubber forming the seal lip 10, a rubber having a shore hardness of 65 Hs or more is used.

The inner circumference of the outer ring 3 is provided with a raceway groove 11 on which the ball 5 rolls and a seal fixing groove 12. The raceway groove 11 is formed so as to extend in the circumferential direction on the inner circumference of the outer ring 3. The ball 5 is in rolling contact with the inner surface of the raceway groove 11. The seal fixing grooves 12 are formed so as to extend in the circumferential direction on both sides of the track groove 11 in the axial direction. The outer diameter side end portion of the seal member 7 is fitted and fixed in the seal fixing groove 12.

On the outer circumference of the inner ring 2, a raceway groove 13 on which the ball 5 rolls and a seal sliding contact surface 14 on which the seal lip 10 of the seal member 7 slides are provided. The raceway groove 13 is formed so as to extend in the circumferential direction on the outer circumference of the inner ring 2. The ball 5 is in rolling contact with the inner surface of the raceway groove 13. The seal sliding contact surface 14 is formed so as to be continuous in the circumferential direction on both sides of the raceway groove 13 in the axial direction. Here, the seal sliding contact surface 14 is a cylindrical surface. The seal sliding contact surface 14 may be a conical surface (for example, the side surface of the seal sliding contact groove when the seal sliding contact groove that is in sliding contact with the seal lip 10 is formed on the outer periphery of the inner ring 2).

As shown in FIG. 2, on the surface of the seal lip 10 facing the seal sliding contact surface 14 (here, the inner end surface in the radial direction), a circumferential protrusion 15 extending continuously in the circumferential direction and an axial direction of the circumferential protrusion 15 Axial protrusions 16 extending in the axial direction from the side surface along the seal sliding contact surface 14 are formed at the same height as or lower than the circumferential protrusions 15. The ridgeline of the axial protrusion 16 is parallel to the seal sliding contact surface 14.

The circumferential protrusion 15 is formed without interruption over the entire circumference, and the annular space 4 is sealed by contacting the seal sliding contact surface 14 on the entire circumference. That is, the circumferential protrusion 15 is not provided with an air passage (slit or the like penetrating in the axial direction) that communicates between the inside and the outside of the annular space 4. The circumferential protrusion 15 is arranged at the axially outer end of the surface of the seal lip 10 facing the seal sliding contact surface 14, and the axial protrusion 16 is arranged adjacent to the inside of the circumferential protrusion 15 in the axial direction. .. The circumferential protrusion 15 is formed so that the cross-sectional shape (cross-sectional shape shown in FIG. 2) along the plane including the axial center is arcuate. When the seal member 7 is removed from the bearing 1 with a seal, the difference between the height of the axial protrusion 16 and the height of the circumferential protrusion 15 is less than 0.5 mm (preferably 0.3 mm or less, more preferably 0.2 mm). The following) is set.

As shown in FIGS. 3A and 3B, a plurality of axial protrusions 16 are formed at a constant pitch in the circumferential direction. The axial projection 16 is an arc-shaped projection having an arc-shaped cross section along a surface extending in the circumferential direction orthogonal to the seal sliding contact surface 14 (here, a plane perpendicular to the axial center of the bearing). Here, the case where the seal sliding contact surface 14 is a cylindrical surface has been described as an example, but when the seal sliding contact surface 14 is a conical surface, the axial projection 16 is the seal sliding contact surface 14. An arcuate protrusion having an arcuate cross section along a conical surface orthogonal to (conical surface) can be formed. The circumferential pitch of the axial protrusion 16 is 3.0 mm or less (preferably 2 mm or less). The height of the axial protrusion 16 is 0.04 mm or more.

As shown in FIG. 5, the sealed bearing 1 can be used as a rolling bearing that rotatably supports the rotating shafts (here, the input shaft 20 and the output shaft 21) of an automobile transmission. The transmission shown in FIG. 5 includes an input shaft 20 to which the rotation of the engine is input, an output shaft 21 provided parallel to the input shaft 20, and a plurality of gear trains 22 for transmitting rotation from the input shaft 20 to the output shaft 21. _{1 to} 22 _4, and a clutch (not shown) incorporated between the input shaft 20 or output shaft 21 and the gear train 22 1 _to 22 _4, used by selectively engaging the clutches switching the gear train 22 1 _to 22 _4, thereby, thereby changing the gear ratio of the rotation to be transmitted from the input shaft 20 to the output shaft 21. The rotation of the output shaft 21 is output to the output gear 23, and the rotation of the output gear 23 is transmitted to the differential gear 24. The input shaft 20 and the output shaft 21 are rotatably supported by bearings 1 with seals, respectively. Further, in this transmission, the transmission oil is supplied to the side surface of each sealed bearing 1 by the splash of the transmission oil accompanying the rotation of the gear 24 or by the injection of the transmission oil from the nozzle provided inside the housing 25. It is supposed to be done.

By the way, the tightening allowance of the seal lip 10 may change due to the dimensional accuracy and temperature change of the seal member 7, the inner ring 2, and the outer ring 3, the internal clearance of the bearing, the angular runout of the bearing, and the like. Further, when the temperature of the bearing rises once and then falls, a pressure difference is generated between the inside and the outside of the bearing partitioned by the seal member 7, and the pressure difference causes the seal lip 10 of the seal member 7. May occur on the seal sliding contact surface 14 (adhesion phenomenon of the seal lip 10). In this case, the tightening allowance of the seal lip 10 becomes large, which may cause an excessive seal torque or abnormal heat generation of the bearing.

On the other hand, in this bearing 1 with a seal, even when the tightening allowance of the seal lip 10 increases due to dimensional accuracy, temperature change, adsorption phenomenon of the seal lip 10, etc., the axial protrusion 16 of the seal lip 10 and the seal friction An oil film due to the wedge effect is formed between the contact surface 14 and the oil film, and the frictional resistance between the axial protrusion 16 and the seal sliding contact surface 14 is suppressed to be small. That is, when the tightening allowance of the seal lip 10 is increased, the seal torque is increased by the circumferential protrusion 15, but the increase in the seal torque by the axial protrusion 16 is due to the increase in the seal torque contact surface between the axial protrusion 16 and the seal sliding surface. Since it is suppressed to be small by the effect of the oil film formed by the wedge effect between the 14 and 14, the increase in the sealing torque is suppressed as a whole. Further, since the circumferential protrusion 15 extending continuously in the circumferential direction over the entire circumference comes into contact with the seal sliding contact surface 14 on the entire circumference, it is possible to seal the bearing space with high sealing performance.

Further, in the bearing 1 with a seal, the difference between the height of the axial protrusion 16 and the height of the circumferential protrusion 15 is set to less than 0.5 mm (preferably 0.3 mm or less, more preferably 0.2 mm or less). Therefore, when the tightening allowance of the seal lip 10 is increased, the axial protrusion 16 slides into contact with the seal sliding contact surface 14 via the oil film to maintain the posture of the seal lip 10 and covers the entire circumference of the circumferential protrusion 15. It is possible to maintain stable contact between the circumferential protrusion 15 and the seal sliding contact surface 14.

Further, since the seal lip 10 is formed of rubber having a shore hardness of 65 Hs or more, the bearing 1 with a seal is stable even when dimensional accuracy, temperature change, adsorption phenomenon of the seal lip 10 or the like occurs. It is possible to secure the sealed performance.

Further, since the bearing 1 with a seal employs an arcuate projection 16 having an arcuate cross section along a surface extending in the circumferential direction orthogonal to the seal sliding contact surface 14, the seal sliding Lubricating oil adhering to the contact surface 14 is likely to be introduced between the seal sliding contact surface 14 and the axial protrusion 16 of the seal lip 10. Therefore, it is possible to stably form an oil film due to the wedge effect between the axial protrusion 16 and the seal sliding contact surface 14.

Further, in the bearing 1 with a seal, the pitch in the circumferential direction of the axial protrusion 16 is 3.0 mm or less (preferably 2 mm or less), so that a wedge effect is formed between the axial protrusion 16 and the seal sliding contact surface 14. It is possible to stably form an oil film.

As shown in FIG. 4, it is also possible to adopt a seal member 7 having a garter spring 17 that tightens the seal lip 10 from the outer diameter side. The garter spring 17 is a spring member in which both ends of an elongated coil spring are connected to form an annular shape.

In the above embodiment, the sealed bearing 1 used as a rolling bearing that rotatably supports the rotating shaft of the transmission of the automobile has been described as an example, but the present invention has been described by exemplifying the differential gear, the constant velocity joint, and the propeller of the automobile. It can also be applied to bearings 1 with seals used for rotating parts such as shafts, turbochargers and hubs, and rotating parts of machine tools and wind generators.

Further, in the above embodiment, a bearing of a type using a ball 5 as a rolling element has been described as an example, but the present invention may be applied to a bearing of a type using a cylindrical roller or a tapered roller as a rolling element. Good.

Further, in the above embodiment, the bearing 1 with an oil-lubricated seal lubricated by the lubricating oil supplied from the outside of the bearing has been described as an example, but the present invention has described the bearing space with grease sealed in the grease-lubricated seal. It can also be applied to the attached bearing 1.

Further, in the above embodiment, the bearing 1 with a seal in which the seal sliding contact surface 14 is formed on the inner ring 2 and the seal member 7 is fixed to the outer ring 3 has been described as an example, but the present invention has described the seal sliding on the outer ring 3. It can also be applied to a bearing 1 with a seal having a contact surface 14 formed and a seal member 7 fixed to the inner ring 2.

Further, in the above embodiment, the bearing 1 with a seal in which the seal members 7 are provided on both sides of the annular space 4 has been described as an example, but the seal member 7 may be provided only on one side of the annular space 4. ..

It should be considered that the embodiments disclosed this time are exemplary in all respects and not restrictive. The scope of the present invention is shown by the scope of claims rather than the above description, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

1 Bearing with seal 2 Inner ring 3 Outer ring 4 Circular space 5 Ball 7 Seal member 10 Seal lip 14 Seal sliding contact surface 15 Circumferential protrusion 16 Axial protrusion 17 Garter spring

Claims

Inner ring (2) and
An outer ring (3) coaxially provided on the outer side in the radial direction of the inner ring (2),
A plurality of rolling elements (5) incorporated in an annular space (4) formed between the inner ring (2) and the outer ring (3),
It has an annular seal member (7) that closes the end opening of the annular space (4).
A seal in which the seal member (7) is in sliding contact with a seal sliding contact surface (14) continuous in the circumferential direction formed on one of the bearing rings of both the inner ring (2) and the outer ring (3). In a sealed bearing with a lip (10)
The seal lip (10) is
Circumferential protrusions (15) extending continuously in the circumferential direction without interruption over the entire circumference so as to seal the annular space (4) by contacting the seal sliding contact surface (14) on the entire circumference.
It extends axially from the axial side surface of the circumferential protrusion (15) along the seal sliding contact surface (14) at the same height as or lower than the circumferential protrusion (15) and is constant in the circumferential direction. A bearing with a seal characterized by having a plurality of axial protrusions (16) formed at a pitch.
The bearing with a seal according to claim 1, wherein the difference between the height of the axial protrusion (16) and the height of the circumferential protrusion (15) is set to less than 0.5 mm.
The bearing with a seal according to claim 1 or 2, wherein the seal lip (10) is made of rubber having a shore hardness of 65 Hs or more.
The aspect according to any one of claims 1 to 3, wherein the axial protrusion (16) is an arc-shaped protrusion having an arc-shaped cross section along a surface extending in the circumferential direction orthogonal to the seal sliding contact surface (14). Bearing with seal.
The bearing with a seal according to any one of claims 1 to 4, wherein the axial pitch of the axial protrusion (16) is 3.0 mm or less.
The bearing with a seal according to any one of claims 1 to 5, wherein the seal sliding contact surface (14) is a cylindrical surface.
The bearing with a seal according to claim 6, which has a garter spring (17) for tightening the seal lip (10) from the outer diameter side.