JP2020101235A - Bearing sealing device - Google Patents

Abstract

To provide a bearing sealing device for putting a lip in contact with another member to seal a bearing space, thus achieving lower torque while maintaining sealability.SOLUTION: A bearing sealing device 12 includes a seal member 16 sealing the bearing space, fixed to a core metal 15 to be relatively and coaxially rotated for contacting a slinger 18, the seal member 16 having an outside seal lip 23 for contacting the slide surface of a rising plate part 22 of the slinger 18. In proportion as being apart from a contact region between the front edge of the outside seal lip 23 and the slide surface to a bearing space side, a clearance distance between the surface of the outside seal lip 23 and the slide surface increases. The increase rate of the clearance distance is higher in an area farther from the contact region than in an area nearer the contact region.SELECTED DRAWING: Figure 2

Description

The present invention relates to a contact type bearing sealing device having a lip, which is mounted between an inner member and an outer member to seal a bearing space.

Prevents grease from leaking from the bearing space between the inner and outer rings and the ingress of foreign matter such as water and dust from the outside, as in rolling bearings used in automobile accessory pulleys and electromagnetic clutches for air conditioner compressors. To achieve this, a bearing sealing device is used to seal the bearing space. Particularly, in a device that requires high sealing performance, a contact type bearing sealing device that seals a bearing space by bringing a seal member formed of an elastic member into contact with a sliding surface provided on an inner ring or an outer ring is used. There is.

The sealing property of the configuration in which the lip of the seal member is in contact with the sliding surface of the mating member is affected by the angle (contact angle) formed by the surface of the lip tip and the sliding surface of the mating member. For example, if this contact angle is small, the sealing performance will improve due to an increase in the contact area at the lip tip, but the shear resistance of grease will increase due to the increase in the contact area and the grease adhesion area near the contact area. , The torque also increases. On the other hand, when the contact angle is large, the torque is reduced, but it becomes difficult to secure the sealing property. Further, it is conventionally known that the magnitude relationship between the contact angle on the bearing space side (inner space side) and the contact angle on the opposite side (outer space side) also affects the sealability (see Non-Patent Document 1). ).

Based on these, for example, in Patent Document 1, there is provided a contact type bearing sealing device having a lip, which includes an end portion of the outermost diameter lip that contacts the counterpart member and a counterpart member that contacts the outermost diameter lip. The contact angle in the state where the tightening margin formed by the contacted surface is added is 40 to 90°. Further, the yield stress of the grease is set to a specific value or more in order to secure the sealing property while keeping the contact angle within the range.

Further, the sealing device of Patent Document 2 is a device in which the tip edge of the seal lip is slidably in contact with the surface of a mating member over the entire circumference, and the contact angle between the tip edge of these seal lip and the other member on the internal space side. Is from 13 to 45°.

Kawahara, "Sealing of Oil Seal and Friction and Wear", Journal of Japan Rubber Association, 1988, Vol. 61, No. 5, p. 355-362

JP, 2008-59586, A JP, 2007-239987, A

However, if the contact angle is increased in order to reduce the torque, the sealing property will deteriorate. Further, if the contact angle is changed to secure the sealing property, it will be difficult to maintain a low torque. There is room for further improvement in the technology of each of the above patent documents in terms of achieving both sealing performance and low torque.

The present invention has been made in view of the above problems, and in a bearing sealing device that seals a bearing space by bringing a lip into contact with a mating member, a bearing sealing device that achieves low torque while maintaining sealing performance. The purpose is to provide.

The bearing sealing device of the present invention seals a bearing space, is fixed to one member of an inner member and an outer member that relatively rotate coaxially, and is provided with a seal member that is in contact with a mating member that is the other member. In the device, the seal member has a lip that comes into contact with the sliding surface of the mating member, and the lip is separated from the contact area between the tip end edge of the lip and the sliding surface toward the bearing space side. The distance between the surface and the sliding surface is increased, and the increase rate of the distance in the clearance is larger in the distance from the contact area than in the vicinity of the contact area.

In the present invention, “near the contact area” means that, when the contact length of the contact area in the axial cross section of the bearing sealing device is used as a reference, the contact length is 3 times the contact length from the end on the bearing space side of the contact area. A part less than the length. As a concrete numerical value, when the contact length is 0.1 mm, it means a portion less than 0.3 mm from the end of the contact area on the bearing space side. Further, the "distance from the contact area" means a portion separated from the end on the bearing space side of the contact area by three times or more of the contact length. As a concrete numerical value, when the contact length is 0.1 mm, it means a portion separated by 0.3 mm or more from the end of the contact area on the bearing space side.

The seal member has a bending point on its surface, the inclination angle of which changes with respect to the sliding surface, and the angle formed by the surface of the lip on the root side of the bending point and the sliding surface is the bending point. It is characterized in that it is larger than the angle formed by the surface of the lip and the sliding surface on the tip side.

The mating member has, on its sliding surface, a bending point whose inclination angle with respect to the surface of the lip changes, and the angle between the sliding surface and the surface of the lip on the side opposite to the contact point from the bending point is The angle is larger than the angle formed by the sliding surface and the surface of the lip on the contact area side with respect to the bending point.

The sliding surface of the mating member has an arc-shaped cross section.

The bending point is formed at a position distant from the end of the contact area on the bearing space side by three times or more of the contact length of the contact area.

In the bearing sealing device of the present invention, the distance between the lip and the mating member is increased as the distance from the contact area increases, and the increase rate is made greater in the distance from the contact area than in the vicinity of the contact area. That is, the rate of increase is small near the contact area and large at positions away from the contact area. In this case, since the increase rate of the gap is small in the vicinity of the contact area, that is, the contact angle is small, the sealing performance can be secured. On the other hand, the gap increases as the distance from the contact area increases, so that the shear resistance of the grease is reduced and the torque can be reduced with a decrease in the grease adhesion area. As a result, it is possible to reduce the torque while maintaining the sealing property.

It is a longitudinal section showing an example of a rolling bearing to which a bearing sealing device of the present invention is applied. It is an expanded sectional view which shows the bearing sealing device by the side of the inboard of FIG. It is an expanded sectional view which shows the bearing sealing device by the side of the outboard of FIG. It is a longitudinal section showing another example of a rolling bearing to which the bearing sealing device of the present invention is applied. It is an expanded sectional view which shows the bearing sealing device of FIG. It is a figure which shows an example of a structure near the contact area of the seal lip of FIG. It is a figure which shows the other example of a structure near the contact area of the seal lip of FIG. It is a figure which shows the other example of a structure near the contact area of the seal lip of FIG. It is a figure which shows the structure near the contact area of the conventional seal lip.

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a longitudinal sectional view showing an example of a sealed type rolling bearing to which the bearing sealing device of the present invention is applied. This sealed type rolling bearing is applied to a wheel bearing that rotatably supports a drive wheel of an automobile with respect to a suspension device. This wheel bearing is a wheel bearing on the drive wheel side, and has a vehicle body mounting flange 2 integrally attached to a vehicle body (not shown) on the outer periphery, and double row outer raceway surfaces 8, 8 on the inner periphery. The formed outer member 1 and a wheel mounting flange 7 to which a wheel (not shown) is mounted at one end are integrally formed, and one inner raceway which opposes the outer raceway surfaces 8 of the above-mentioned double row on the outer circumference A surface 9a, a cylindrical small-diameter step portion 14 extending axially from the inner raceway surface 9a are formed, and a hub wheel 4 having a serration 6 for torque transmission formed on the inner periphery thereof and a small-diameter step portion 14 are press-fitted. , And the inner race 5 having the other inner raceway surface 9b formed on the outer circumference.

A double row rolling element (ball) 10 is accommodated between a double row outer raceway surface 8, 8 and inner raceway surfaces 9a, 9b facing each other so as to be rollable by a cage 11. Further, bearing sealing devices 12 and 26 are formed in the annular space formed between the inner member 3 serving as the rotating side member and the outer member 1 serving as the fixed side member, which is composed of the hub wheel 4 and the inner ring 5. It prevents the leakage of the lubricating grease that is installed in each bearing and sealed inside the bearing, and prevents rainwater and dust from entering the bearing from the outside.

Of these bearing sealing devices 12 and 26, the inboard side (the right side in the drawing) bearing sealing device 12 mounted between the outer member 1 and the inner ring 5 is installed in the outer member 1 as shown in FIG. A seal ring 17 which is fitted and formed in an L-shaped cross section, and a seal member 16 integrally vulcanized and adhered to the core bar 15, and an outer ring that is externally fitted to the inner ring 5 and also has an L-shaped cross section. And a slinger 18 formed into a shape. The slinger 18 and the core metal 15 of the seal ring 17 are formed by pressing austenitic stainless steel sheet (JIS standard SUS304 series, etc.) or rustproof cold rolled steel sheet (JIS standard SPCC series, etc.). It is formed in.

The seal member 16 is made of an elastic member such as rubber, and is provided with three seal lips 23, 24, 25 on the outer side, the middle side, and the inner side. The tip edge of the outer seal lip 23 is provided on the inner surface of the standing plate portion 22 of the slinger 18. The leading edges of the remaining intermediate seal lip 24 and inner seal lip 25 are brought into sliding contact with the cylindrical portion 21 of the slinger 18.

On the other hand, the bearing sealing device 26, as shown in FIG. 3, is internally fitted to the outer member 1 and has a metal core 13 formed in an annular shape, and a seal member integrally vulcanized and bonded to the metal core 13. 27 and. The core metal 13 is formed by pressing an austenitic stainless steel plate (JIS standard SUS304 system or the like) or a rust-proof cold rolled steel plate (JIS standard SPCC system or the like). The seal member 27 is made of an elastic member such as rubber and is provided with two side lips (dust seals) 28a and 28b and a single radial lip (grease seal) 28c. Is directly in sliding contact with a sliding surface 19 formed in an arc shape on the inboard side base of the wheel mounting flange 7.

As the material of the seal members 16 and 27, nitrile rubber, acrylic rubber, silicone rubber, fluororubber or the like is used. If these rubbers are used in excess of the heat resistance, they may be thermally deteriorated and hardened to impair elasticity, and in extreme cases, lips may be cracked and sealing performance may be deteriorated. For this reason, it is preferable to select it appropriately according to the use environment (temperature).

Here, the contact state between the outer seal lip 23 and the sliding surface of the slinger 18 shown in FIG. 2 will be described using a conventional example. FIG. 9 shows a conventional structure in a portion corresponding to the area A in FIG. As shown in FIG. 9, the leading edge of the outer seal lip 23 is in contact with the sliding surface 22a of the standing plate portion of the slinger in the contact area D in a state in which the interference is applied. On the bearing space side, the surface 23a of the outer seal lip 23 and the sliding surface 22a are in contact with each other at a contact angle θ. The contact length of the contact area D in the axial section of the bearing is L.

In FIG. 9, a predetermined amount of grease 41 is attached to the gap between the outer seal lip 23 and the sliding surface 22a. The distance of the gap increases in proportion to the distance from the contact area D, and the increase rate of the distance of the gap is constant. Here, the distance of the gap (also referred to as the distance between the seal lip and the mating member) refers to the length of a perpendicular line drawn from the surface 23a of the outer seal lip to the sliding surface 22a, which will be described later with reference to FIGS. The same applies to FIG. When the bearing rotates, the shear resistance of the grease 41 may become a torque factor. In particular, when the adhesion area S _{4 of} the grease 41 to the sliding surface 22a becomes large, the torque increases.

Therefore, in the three examples of FIGS. 6 to 8 according to the present invention, in a configuration in which the distance between the seal lip and the mating member increases as the distance from the contact area increases, the increase rate of the distance is farther from the contact area than near the contact area. Is set to be larger. As a result, it is possible to reduce the adhesion area of grease while ensuring the contact length of the contact area. 6 to 8 show the case where the amount of grease 41 attached to the gap between the outer seal lip and the sliding surface is the same as that in FIG. 9. Each figure will be described below.

In FIG. 6, the outer seal lip 23 has, on its surface 23a, a bending point P ₁ at which the slant angle of the slinger with respect to the sliding surface 22a changes. The angle (contact angle) θ _1a formed with the sliding surface 22a is smaller on the tip side (contact area side) than the bending point P ₁ and is the sliding surface 22a on the root side (anti-contact area side) with respect to the bending point P _1. The angle θ _1b is increased. In this case, the angle between the surface 23a and the sliding surface 22a of the outer seal lip, towards the angle of the root side than the bending point P ₁ is larger than the angle of the tip side (θ _1b> θ _1a). As long as this magnitude relationship is satisfied, θ _1a and θ _1b are not particularly limited. For example, it is preferable that θ _1a is 10 to 50° and θ _1b is 20 to 90°.

Providing the bending point as shown in FIG. 6 increases the distance between the seal lip and the mating member on the root side from the bending point P ₁ as compared with the conventional configuration having no bending point (FIG. 9). As a result, the adhesion area S ₁ of the grease 41 to the sliding surface 22a, which is a torque factor, can be made smaller than the adhesion area S _{4 of} FIG. 9, and the torque is reduced.

Here, if the position of the bending point P _{1 is set to} a position that does not significantly affect the surface pressure distribution of the contact area D, it can be applied without changing the sealing property. The position of the bending point P ₁ that does not significantly affect the surface pressure distribution can be accurately obtained by finite element analysis or the like, but in a simple manner, from the end of the contact area D on the bearing space side to the contact length L It is preferable that the positions are three times or more. The reason why the number is three times or more will be described below.

Assuming that the seal lip is a semi-infinite elastic body, the effect of the stress acting on a point on the displacement of another point of interest is inversely proportional to the distance between the point and the point of interest. In consideration of this, if the position of the bending point is located at a position more than three times the contact length L from the end of the contact area D, the influence on the contact surface pressure will be about 1/3 or less, and the sealing property will be reduced. It is thought that it will not have a large effect on. The position of the bending point P ₁ is more preferably a position of 3 times or more and 5 times or less of the contact length L from the end of the contact area D on the bearing space side, and a position of 3 times or more and 4 times or less of the contact length L. More preferable.

The contact length L may vary depending on the material of the seal member, the tightening margin, and the size of the seal, but is 0.03 to 1 mm, for example. Considering this, the bending point P ₁ is formed, for example, at a position 0.09 to 3 mm away from the end of the contact area D on the bearing space side.

In FIG. 7, the sliding surface 22a of the slinger has a bending point P ₂ where the inclination angle of the outer seal lip with respect to the surface 23a changes. The inflection point angle formed between the surface 23a in the contact area side than P ₂ (contact angle) theta _2a a small and by increasing the angle theta _2b formed with the root side (counter-contact area side) the surface 23a than the bending point P ₂ .. In this case, the angle between the surface 23a and the sliding surface 22a of the outer seal lip, towards the angle of the root side than the bending point P ₂ is greater than the angle of the tip side (θ _2b> θ _2a). As long as this magnitude relationship is satisfied, θ _2a and θ _2b are not particularly limited. For example, it is preferable that θ _2a is 10 to 50° and θ _2b is 20 to 90°.

Also in the configuration of FIG. 7, the distance between the seal lip and the mating member increases on the root side from the bending point P ₂ as compared with the conventional configuration (FIG. 9). As a result, the adhesion area S ₂ of the grease 41 on the sliding surface 22a, which is a torque factor, can be made smaller than the adhesion area S _{4 of} FIG. 9, and the torque is reduced. Further, the position of the bending point P ₂ is preferably set to a position that is apart from the end of the contact area D on the bearing space side by 3 times or more of the contact length L, similarly to the bending point P ₁ .

In the example of FIG. 8, the sliding surface 22a of the slinger has an arcuate cross section. This arc has a center of curvature opposite the outer seal lip surface 23a. In the configuration of FIG. 8 as well, the distance between the seal lip and the mating member increases at a distance from the contact area as compared with the conventional configuration (FIG. 9). Therefore, the adhesion area S ₃ of the grease 41 to the sliding surface 22a, which is a torque factor, can be made smaller than the adhesion area S _{4 of} FIG. 9, and the torque is reduced.

In the examples of FIGS. 6 and 7, the bending point is provided only on one side (bearing space side), but it may be provided on both sides (bearing space side and external space side). Even when the bending point is provided on the external space side, the angle formed by the surface of the seal lip and the sliding surface of the mating member on the root side of the bending point is larger than that on the tip side. preferable. Further, in the examples of FIGS. 6 to 8, the contact angle on the external space side is made larger than that on the bearing space side in order to prevent the entry of foreign matter from the outside, but the configuration is not limited to this. For example, in order to prevent leakage of grease, the contact angle on the bearing space side may be made larger than the contact angle on the external space side.

6 to 8, the configuration around the contact area of the present invention has been described using the outer seal lip 23, but the invention is not limited to this, and the intermediate seal lip 24, the inner seal lip 25, the side lips 28a, 28b, the radial. A similar configuration can be applied to the lip 28c. In the case of a bearing sealing device having a plurality of lips like the bearing sealing devices 12 and 26, the configuration in the vicinity of the contact area of at least one sealing lip among the plurality of sealing lips increases the distance between the sealing lip and the mating member. It suffices that the ratio be larger in the far side of the contact area than in the vicinity of the contact area. Preferably, all seal lips are of this construction.

FIG. 4 is a vertical cross-sectional view showing another example of a sealed type rolling bearing to which the bearing sealing device of the present invention is applied. The hermetically sealed rolling bearing 20 is a deep groove ball bearing, and has an outer ring 30 having an outer raceway surface 29 formed on the inner circumference, an inner race 32 having an inner raceway surface 31 formed on the outer circumference, and between the raceway surfaces 29, 31. A pair of seal rings 35, 35 are mounted in a ball 34 rotatably housed by a cage 33 and an annular space formed between the inner and outer rings 32, 30. The pair of seal rings 35, 35 prevent leakage of the grease filled in the bearing and prevent rainwater, dust and the like from entering the bearing from the outside.

FIG. 5 is an enlarged view of the inner diameter side end portion of the seal member of the rolling bearing of FIG. As shown in FIG. 5, the seal ring 35 is a disc-shaped core metal 36 formed by pressing cold-rolled steel sheet (JIS standard SPCC system, etc.), and is integrally added to the core metal 36. It is composed of a sealing member 37 which is adhesively bonded with sulfur. The seal member 37 has a main lip 37a and a sub-lip 37b whose tip is branched into two branches. The seal ring 35 is fitted to the inner periphery of the end portion of the outer ring 30 via the seal member 37, and the seal member 37 is inserted into the seal groove 38 formed in the outer periphery of the end portion of the inner ring 32 and having a substantially U-shaped cross section. It is in direct sliding contact. Specifically, the main lip 37a is in contact with the slanted sliding surface 39 of the seal groove 38, and the sub lip 37b is in contact with the small-diameter portion (ridge portion of the seal groove) 40.

The configurations shown in FIGS. 6 to 8 can be applied to the main lip 37a and the sub lip 37b in FIG. For example, in the case of the main lip 37a, a bending point is provided on the surface of the main lip 37a, and the angle formed by the surface of the main lip 37a and the sliding surface 39 is closer to the tip side than the bending point. It can be larger than the angle.

In the examples of FIGS. 4 and 5, a deep groove ball bearing is exemplified as the hermetically sealed rolling bearing, but the bearing sealing device of the present invention is a cylindrical roller bearing, a tapered roller bearing, a self-aligning roller bearing, a needle roller other than the above. It can also be used as bearings, thrust cylindrical roller bearings, thrust tapered roller bearings, thrust needle roller bearings, thrust self-aligning roller bearings, and the like.

INDUSTRIAL APPLICABILITY Since the bearing sealing device of the present invention can achieve low torque while maintaining the sealing property, it can be widely used as a bearing sealing device for a sealed rolling bearing that seals grease in the bearing space.

1 Outer member (outer member)
2 Body mounting flange 3 Inner member (inner member)
4 Hub wheel (inner member)
5,32 Inner ring (inner member)
6 Serration 7 Wheel Mounting Flange 8, 29 Outer Raceway Surface 9a, 9b, 31 Inner Raceway Surface 10 Rolling Element 11, 33 Cage 12, 26 Bearing Sealing Device 13, 15, 36 Core Bar 14 Small Diameter Step 16, 27, 37 Seal member 17, 35 Seal ring 18 Slinger 19, 39 Sliding surface 20 Sealing type rolling bearing 21 Cylindrical part 22 Standing plate part 23 Outer seal lip 24 Intermediate seal lip 25 Inner seal lip 28a, 28b Side lip 28c Radial lip 30 Outer ring ( Outer member)
34 Ball 37a Main Lip 37b Sub Lip 38 Seal Groove 40 Small Diameter Part 41 Grease

Claims (5)

A bearing sealing device comprising a seal member that seals a bearing space, is fixed to one member of an inner member and an outer member that relatively rotate coaxially, and is in contact with a mating member that is the other member,
The seal member has a lip that comes into contact with the sliding surface of the mating member,
As the distance from the contact area between the tip edge of the lip and the sliding surface increases toward the bearing space side, the distance between the lip surface and the sliding surface increases, and the increase ratio of the distance in the clearance makes contact. A bearing sealing device, characterized in that it is larger in the contact area farther than in the vicinity of the area. The seal member has, on its surface, a bending point at which an inclination angle with respect to the sliding surface changes.
An angle formed by the surface of the lip on the root side of the bending point and the sliding surface is larger than an angle formed by the surface of the lip on the tip side of the bending point and the sliding surface. The bearing sealing device according to claim 1. The mating member has, on its sliding surface, a bending point at which the angle of inclination with respect to the surface of the lip changes.
An angle formed by the sliding surface and the surface of the lip on the side of the contact area opposite to the bending point is larger than an angle formed by the sliding surface and the surface of the lip on the side of the contact area from the bending point. The bearing sealing device according to claim 1, wherein: The bearing sealing device according to claim 1, wherein the sliding surface of the mating member has an arcuate cross section. 4. The bending point is formed at a position distant from the end of the contact area on the bearing space side by 3 times or more of the contact length of the contact area. Bearing sealing device.

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