JP7723087B2 - sealing device - Google Patents

Description

The present invention relates to a sealing device.

A rolling bearing that supports the axle is installed in the hub of an automobile. This rolling bearing is called a hub bearing. A sealing device is installed between the inner and outer rings of the hub bearing. This sealing device seals in the lubricant (grease) inside the bearing and prevents foreign objects such as water and dust from entering the inside of the bearing from the outside.

There are two types of hub bearings: inner ring rotating type and outer ring rotating type (Patent Document 1). In the inner ring rotating type, the outer ring is fixed to the vehicle body, and the inner ring and hub fixed to the axle rotate together with the axle. This type rotates together with the wheel, so it is used both when the wheel is a driving wheel and when the wheel is a driven wheel. In the outer ring rotating type, the inner ring is fixed to a stationary axle, and the outer ring fixed to the wheel rotates together with the wheel. This type is used when the wheel is a driven wheel, because the axle is stationary.

International Publication No. 2015/182357

Some sealing devices installed in hub bearings have a seal member fixed to the outer ring, which is the outer component, and another seal member fixed to the inner ring, which is the inner component. These seal members are in sliding contact with each other.

Generally, to ensure the sealing performance of sealing devices installed in hub bearings, the lip of the sealing element that makes sliding contact with other sealing elements is designed with a large interference. However, designing the lip interference to be large increases the contact pressure of the lip, and therefore the torque applied to the rotating element. Furthermore, lip wear and temperature increases due to frictional heat may shorten the life of the sealing element. In sealing elements used in large hub bearings, the relative speed between the inner and outer rings is high, increasing the risk of lip wear and temperature increases.

Therefore, the present invention provides a sealing device that reduces the torque applied to the rotating members and suppresses lip wear and temperature increases due to frictional heat.

According to one aspect of the present invention, a sealing device is provided that is disposed between a fixed inner member and a rotating outer member and seals a gap between the inner member and the outer member. The sealing device includes a sleeve attached to the inner member, a first seal member having a flange extending radially outward from the sleeve, a tubular portion disposed radially outward from the flange and attached to the outer member, a disc portion extending radially inward from the tubular portion and facing the flange, a radial lip disposed radially inward from the disc portion and in slidable contact with the sleeve, and a side lip extending from the disc portion toward the flange. The side lip of the second seal member slidably contacts the flange when the rotational speed of the outer member is lower than a threshold value, and deforms to move away from the flange when the rotational speed of the outer member is higher than the threshold value.

In this configuration, the side lip of the second seal member attached to the rotating outer member slidably contacts the flange when the rotational speed of the outer member is below a threshold value, ensuring the sealing performance of the sealing device. On the other hand, when the rotational speed of the outer member is above the threshold value, the centrifugal force acting on the side lip itself causes the side lip of the second seal member to deform and move away from the flange. Therefore, the torque acting on the rotating outer member is small, suppressing wear on the side lip and temperature increases due to frictional heat.

According to one aspect of the present invention, there is provided a sealing device disposed between a rotating inner member and a fixed outer member for sealing a gap between the inner member and the outer member. The sealing device includes a first sealing member attached to the outer member and a second sealing member attached to the inner member. The first sealing member has a first rigid ring that is an annular member about an axis formed from a rigid material, and the second sealing member has a second rigid ring that is an annular member about the axis formed from a rigid material, and a second elastic ring that is an annular member about the axis formed from an elastic material. The second elastic ring of the second sealing member has a side lip that is an annular portion about the axis extending along the axis. The first rigid ring of the first sealing member is adapted to be in contact with a tip end of the side lip. The side lip of the second seal member slidably contacts the first rigid ring of the first seal member when the rotational speed of the inner member is less than a threshold value, and deforms to move away from the first rigid ring of the first seal member when the rotational speed of the inner member is greater than a threshold value.

1 is a partial cross-sectional view of an example of a rolling bearing in which a sealing device according to a first embodiment of the present invention is used. 3 is a partial cross-sectional view of the sealing device according to the first embodiment of the present invention when the outer member rotates at a low speed. FIG. 3 is a partial cross-sectional view of the sealing device according to the first embodiment of the present invention when the outer member rotates at high speed. FIG. 1 is a cross-sectional view of an example of an in-wheel motor unit in which a sealing device according to a first embodiment of the present invention is used. FIG. 6 is a partial cross-sectional view of a sealing device according to a second embodiment of the present invention. FIG. 10 is a cross-sectional view of a rolling bearing to which a sealing device according to a second embodiment of the present invention is attached. FIG. 10 is a partial cross-sectional view of a sealing device according to a third embodiment of the present invention. FIG. 10 is a partial cross-sectional view of a sealing device according to a fourth embodiment of the present invention.

Embodiments of the present invention will now be described with reference to the accompanying drawings. The drawings are not necessarily drawn to scale, and some features may be exaggerated or omitted.

Figure 1 shows a hub bearing for an automobile, which is an example of a rolling bearing in which a sealing device according to a first embodiment of the present invention is used. However, the application of the present invention is not limited to hub bearings, and the present invention can also be applied to other rolling bearings. Also, in the following description, the hub bearing is a ball bearing, but the application of the present invention is not limited to ball bearings, and the present invention can also be applied to other rolling bearings having other types of rolling elements, such as roller bearings and needle bearings. The present invention can also be applied to rolling bearings used in machines other than automobiles.

This hub bearing 1 is an outer ring rotating type, with the inner ring fixed to a stationary axle and the outer ring fixed to the wheel rotating with the wheel. Hub bearing 1 has an inner ring (inner member) 6 with a hole 2 into which the axle is inserted, an outer ring (outer member) 8 positioned outside the inner ring 6, a plurality of balls 10 arranged in a row between the inner ring 6 and outer ring 8, a plurality of balls 12 arranged in a row between the inner ring 6 and outer ring 8, and a plurality of cages 14, 15 that hold these balls in place.

The inner ring 6 is fixed to a stationary axle. The outer ring 8 acts as a hub that is fixed to the wheel. Therefore, the outer ring 8 is formed with a hub flange 18, to which the wheel can be attached using hub bolts 19. In this way, the outer ring 8 is fixed to the wheel and rotates together with the wheel. However, the outer ring 8 and hub flange 18 may also be formed as separate components and fixed together.

The common central axis Ax of the axle and hub bearing 1 extends vertically in Figure 1. In Figure 1, only one portion relative to the central axis Ax is shown. Although not shown in detail, the lower side of Figure 1 is the outer side (outboard side) where the wheels of the vehicle are located, and the upper side is the inner side (inboard side) where the differential gear and other components are located. The outer side and inner side shown in Figure 1 refer to the radial outer side and inner side, respectively.

A sealing device 20 that seals the gap between the outer ring 8 and the inner ring 6 is located near the inboard cylindrical end 8A of the outer ring 8. The sealing device 20 prevents grease, i.e., lubricant, from leaking from the internal space of the hub bearing 1, and also prevents foreign matter (including water (including muddy water or salt water) and dust) from entering the interior of the hub bearing 1 from the outside. In Figure 1, arrow F shows an example of the direction in which foreign matter may flow from the outside.

As shown in Figure 2, the sealing device 20 is disposed in the gap between the inboard end 8A of the outer ring 8 of the hub bearing 1 and the inner ring 6 of the hub bearing 1. The sealing device 20 is annular, but Figure 2 shows only one portion of it relative to its central axis. As is clear from Figure 2, the sealing device 20 has a composite structure comprising a first seal member 30 and a second seal member 40.

The first seal member 30 is a fixed seal member that is fixed to the stationary inner ring 6 and does not rotate. The first seal member 30 has a rigid ring 31 made of a rigid material, such as metal. Although not shown, an elastic ring made of an elastic material, such as an elastomer, may be attached to the rigid ring 31.

The rigid ring 31 has a substantially L-shaped cross section. Specifically, the rigid ring 31 comprises a cylindrical sleeve 31A and an annular flange 31B extending radially outward from the sleeve 31A. The sleeve 31A is attached to the inner ring 6. Specifically, the end of the inner ring 6 is fitted into the sleeve 31A by an interference fit. The flange 31B is a flat plate and lies in a plane perpendicular to the axis of the sleeve 31A. The flange 31B is located on the inboard side of the sleeve 31A.

The second seal member 40 is a rotating seal member that is fixed to the rotating outer ring 8 and rotates. The second seal member 40 is a composite structure having an elastic ring 41 and a rigid ring 42. The elastic ring 41 is formed from an elastic material, such as an elastomer. The rigid ring 42 is formed from a rigid material, such as a metal, and reinforces the elastic ring 41. The rigid ring 42 has a substantially L-shaped cross-sectional shape. A portion of the rigid ring 42 is embedded in the elastic ring 41 and is in close contact with the elastic ring 41.

The second sealing member 40 has a tubular portion 44, a disc portion 45, a grease lip (radial lip) 46, a sealing lip (radial lip) 47 and a side lip 48.

The tubular portion 44 is attached to the outer ring 8. Specifically, the tubular portion 44 is fitted into the end portion 8A of the outer ring 8 using an interference fit. The tubular portion 44 is composed of an elastic ring 41 and a rigid ring 42.

The disc portion 45 extends radially inward from the tubular portion 44 and faces the flange 31B of the rigid ring 31 of the first seal member 30. The disc portion 45 is located on the outboard side of the tubular portion 44. The disc portion 45 is also composed of an elastic ring 41 and a rigid ring 42.

The grease lip 46 and the seal lip 47 are positioned radially inside the disc portion 45 and are in sliding contact with the sleeve 31A. The grease lip 46 and the seal lip 47 are formed from an elastic ring 41.

Grease is placed in the space on the outboard side of the disc portion 45 (the internal space of the hub bearing 1) between the outer ring 8 and the inner ring 6. This grease reduces friction between the balls 10, 12, the outer ring 8, and the inner ring 6 (see Figure 1).

The grease lip 46 is a thin plate with a truncated cone or cylindrical cone shape that extends diagonally from the elastic portion at the radially inner end of the disc portion 45 toward the radially inward and outboard side. The tip of the grease lip 46 contacts the outer peripheral surface of the sleeve 31A. The grease lip 46 prevents grease from leaking from the internal space of the hub bearing 1 toward the inboard side.

The seal lip 47 is a protrusion formed on the annular portion 49 that extends inboard from the elastic portion at the radially inner end of the disc portion 45. The annular portion 49 is also composed of an elastic ring 41. In the initial state when the first seal member 30 and the second seal member 40 are not yet assembled, this protrusion has a triangular cross-section as shown by the imaginary lines. The seal lip 47 contacts the outer surface of the sleeve 31A and backs up the grease lip 46. In other words, it prevents grease that passes through the grease lip 46 from the outboard side from leaking to the inboard side.

A garter spring 50 is wound around the outer periphery of the annular portion 49. The garter spring 50 applies a radially inward compressive force to the seal lip 47, increasing the binding force of the seal lip 47 against the sleeve 31A.

The side lip 48 is a thin plate extending from the elastic portion of the disc portion 45 toward the flange 31B. The side lip 48 is composed of an elastic ring 41. The side lip 48 has a thick base portion 51 adjacent to the disc portion 45 and a thin tip portion 52 that extends diagonally from the base portion 51 radially outward and toward the flange 31B and has a truncated cone or cylindrical cone shape. When the outer ring 8 and second seal member 40 rotate at low speeds, the tip portion 52 of the side lip 48 comes into slidable contact with the flange 31B.

The tubular portion 44 is positioned further outward from the outer edge of the flange 31B of the first seal member 30. An annular gap 54 is provided between the tubular portion 44 and the flange 31B of the first seal member 30. Foreign matter can enter the space 55 between the flange 31B of the first seal member 30 and the disc portion 45 of the second seal member 40 from outside the hub bearing 1 through the gap 54. Conversely, foreign matter can be expelled from the space 55 to the outside through the gap 54.

When the outer ring 8 and second seal member 40 are rotating at low speeds (when the rotational speed is lower than the threshold value), the side lip 48 contacts the flange 31B of the first seal member 30, preventing foreign matter that has entered the space 55 from further penetrating toward the seal lip 47. Low-speed rotation includes when the outer ring 8 and second seal member 40 are not rotating. The threshold value is, for example, the rotational speed (or number of revolutions), and may be a constant value or a variable value. For example, the threshold value may change (change over time) depending on the length of use of the sealing device 20, or may change depending on the operating conditions of the sealing device 20, such as the ambient temperature. To reduce the torque applied from the flange 31B to the second seal member 40, the side lip 48 may be coated with grease. This grease is typically a different type from the grease that lubricates the balls 10, 12, outer ring 8, and inner ring 6.

On the other hand, when the outer ring 8 and second seal member 40 rotate at high speeds (when the rotational speed is greater than a threshold value), as shown in Figure 3, the centrifugal force acting on the side lip 48 itself causes the side lip 48, particularly the tip end 52, to deform and move away from the flange 31B of the first seal member 30. Therefore, an annular gap 56 is provided between the tip end 52 of the side lip 48 and the flange 31B. This is because, in the sealing device 20 used in the outer ring rotating hub bearing 1, centrifugal force is applied to the second seal member 40 fixed to the outer ring 8. In this way, the dimensions of the side lip 48 are designed so that when a large centrifugal force is applied to the side lip 48, the tip end 52 moves away from the flange 31B.

When the outer ring 8 and second seal member 40 rotate at high speed, the side lip 48 separates from the flange 31B. However, because the second seal member 40 itself is rotating at high speed, an airflow or centrifugal force is generated inside the space 55 that flows radially outward, expelling any foreign matter that has entered the space 55 to the outside through the gap 54. Furthermore, the airflow or centrifugal force also expels foreign matter from the space 57 radially inside the side lip 48 through the gap 56 into the space 55, and then further through the gap 54 to the outside.

As described above, the side lip 48 of the second seal member 40 attached to the rotating outer ring 8 slidably contacts the flange 31B when the rotational speed of the outer ring 8 is lower than a threshold value, thereby ensuring the sealing performance of the sealing device 20. In other words, the side lip 48 prevents foreign matter that has entered the space 55 from further infiltrating toward the seal lip 47.

On the other hand, when the rotational speed of the outer ring 8 is greater than the threshold value, the side lip 48 of the second seal member 40 is deformed away from the flange 31B due to the centrifugal force acting on the side lip 48 itself. Therefore, the torque acting on the rotating outer ring 8 is small, and wear of the side lip 48 and temperature increases due to frictional heat are suppressed.

Figure 4 is a diagram illustrating another use form of the sealing device 20 according to the first embodiment of the present invention. The sealing device 20 can also be used, for example, in an in-wheel motor unit as shown in Figure 4. An in-wheel motor unit is a drive unit consisting of a hub bearing and a motor integrated together. It is attached to the wheel of a vehicle, supplies motor output to the wheel via the hub bearing to power the wheel, and also converts the wheel's power into electric power via a motor generator to generate electricity.

For example, as shown in Figure 4, an in-wheel motor unit 100 comprises an inner ring rotating hub bearing 3, an outer casing 101 as an outer member attached to the hub bearing 3, an inner casing 102 as an inner member, and a motor generator 103. Specifically, the outer casing 101 is a cylindrical member that forms an inner space to house the hub bearing 3. The outer casing 101 is sandwiched between a hub flange 18 provided on the inner ring 7 of the hub bearing 3 and a brake disc 110 attached to the hub flange 18, and is fixed between the hub flange 18 and the brake disc 110 by fixing the wheel to the inner ring 7 with hub bolts 19.

The inner casing 102 has a cylindrical portion 102a, which is a cylindrical member that forms the inner space that houses the outer ring 9 of the hub bearing 3, and a disc portion 102b, which is a disc-shaped portion that extends radially outward from the inboard end of the cylindrical portion 102a. The cylindrical portion 102a is shaped so that the outer ring 9 is fitted and fixed in the inner space.

As shown in Figure 4, the outer casing 101 and the inner casing 102 are shaped so that the radially inner surface of the outer casing 101 and the radially outer surface of the cylindrical portion 102a of the inner casing 102 face each other, forming an annular space between the outer casing 101 and the cylindrical portion 102a. Also, as shown in Figure 4, the outer casing 101 and the inner casing 102 are shaped so that the inboard end (end 101a) of the outer casing 101 faces the disc portion 102b of the inner casing 102 in the direction of the central axis Ax. An annular gap is formed between the end 101a of the outer casing 101 and the disc portion 102b.

The motor generator 103 is a cylindrical member extending along the central axis Ax and is provided in the annular space between the outer casing 101 and the cylindrical portion 102a of the inner casing 102. Specifically, the motor generator 103 includes a rotor 104 and a stator 105, with the rotor 104 fixed to the outer casing 101 and the stator 105 fixed to the cylindrical portion 102a of the inner casing 102.

In the in-wheel motor unit 100, the sealing device 20 is provided to prevent foreign matter from entering the interior of the in-wheel motor unit 100 through the annular gap between the end portion 101a of the outer casing 101 and the disc portion 102b of the inner casing 102. For example, as shown in FIG. 4, the sealing device 20 is attached between the end portion 101a of the outer casing 101 and the disc portion 102b of the inner casing 102. Specifically, the sleeve 31A of the first seal member 30 is attached to the mounting surface 102c of the disc portion 102b of the inner casing 102 by an interference fit, and the first seal member 30 is fixed to the disc portion 102b of the inner casing 102. Specifically, the tubular portion 44 of the second seal member 40 is tightly fitted onto a mounting surface 101b of the end portion 101a of the outer casing 101, thereby fixing the second seal member 40 to the outer casing 101. The mounting surface 102c of the disk portion 102b of the inner casing 102 is a cylindrical surface extending along the central axis Ax, and the mounting surface 101b of the end portion 101a of the outer casing 101 is a cylindrical surface extending along the central axis Ax. The mounting surfaces 101b and 102c face each other in the radial direction.

The sealing device 20 also functions in the in-wheel motor unit 100 in the same manner as when it is attached to the hub bearing 1 described above (see Figure 3). Specifically, when the outer casing 101 and second seal member 40 rotate at low speeds below a threshold, the side lip 48 of the second seal member 40 attached to the rotating outer casing 101 slidably contacts the flange 31B, ensuring the sealing performance of the sealing device 20. That is, the side lip 48 prevents foreign matter from entering the space 55 and moving further toward the seal lip 47. On the other hand, when the outer casing 101 and second seal member 40 rotate at high speeds above the threshold, the centrifugal force acting on the side lip 48 of the second seal member 40 deforms the side lip 48 away from the flange 31B, forming a gap 56. This reduces the torque applied to the rotating outer casing 101 and also suppresses wear on the side lip 48 and temperature increases due to frictional heat.

Furthermore, when the outer casing 101 and second seal member 40 rotate at high speed, the side lip 48 separates from the flange 31B, but because the second seal member 40 itself is rotating at high speed, an airflow or centrifugal force is generated inside the space 55 that flows radially outward, causing foreign matter that has entered the space 55 to be expelled to the outside through the gap 54. Furthermore, foreign matter is also expelled from the space 57 radially inside the side lip 48 through the gap 56 by the airflow or centrifugal force into the space 55, and then further expelled to the outside through the gap 54.

Some in-wheel motor units are driven at high speeds, and torque reduction through the sealing device is required for such in-wheel motor units. As described above, the sealing device 20 according to the first embodiment of the present invention can reduce the torque applied to the rotating outer casing 101 when the outer casing 101 rotates at a high speed greater than a threshold value. Furthermore, when the outer casing 101 rotates at a high speed greater than a threshold value, wear on the side lip 48 and temperature increases due to frictional heat can be suppressed, thereby preventing performance degradation and shortened lifespan of the sealing device 20. Meanwhile, during this high-speed rotation, airflow or centrifugal force directed radially outward is generated, thereby preventing the intrusion of foreign matter. Thus, the sealing device 20 according to the first embodiment of the present invention can also be suitably used in in-wheel motors.

Next, a sealing device 21 according to a second embodiment of the present invention will be described. The sealing device 21 according to the second embodiment of the present invention differs from the sealing device 20 according to the first embodiment of the present invention in the configuration of the second seal member. Furthermore, the sealing device 21 according to the second embodiment of the present invention is used for an inner ring rotating type application, and differs from the sealing device 20 described above in the application. Below, with regard to the configuration of the sealing device 21, components that are the same as or have similar functions to the sealing device 20 will be assigned the same reference numerals and their description will be omitted, and only different components will be described.

As shown in FIG. 5, the annular sealing device 21 includes a first seal member 30 of the sealing device 20 described above and a second seal member 60 that is different from the second seal member 40 of the sealing device 20 described above. The second seal member 60 has the rigid ring 42 of the second seal member 40 of the sealing device 20 described above, and also has an elastic ring 61 that is different from the elastic ring 41 of the second seal member 40 of the sealing device 20 described above. Note that FIG. 5 shows only one portion of the sealing device 21 relative to the axis x. Also, FIG. 5 shows the sealing device 21 in a state (position) during use, which will be described later.

The elastic ring 61, like the elastic ring 41 of the second seal member 40 of the sealing device 20, is formed of an elastic material, such as an elastomer. Like the elastic ring 41, the elastic ring 61 is attached to the rigid ring 42; specifically, the elastic ring 61 is in close contact with a portion of the rigid ring 42, and a portion of the rigid ring 42 is embedded in the elastic ring 61.

As shown in Figure 5, the elastic ring 61 of the second seal member 60 has a tubular portion 44, a disc portion 45, and a side lip 62, similar to the elastic ring 41 of the second seal member 40. However, unlike the elastic ring 41 of the second seal member 40, it does not have a grease lip (radial lip) 46 or a seal lip (radial lip) 47. Furthermore, unlike the second seal member 40, the second seal member 60 does not have a circular portion 49 or a garter spring 50.

The side lip 62 has a shape similar to the side lip 48 of the second seal member 40 and is a thin, plate-shaped elastic ring 61 portion extending from the elastic portion of the disk portion 45 toward the flange 31B. The side lip 62 has a thick, annular base portion 62a adjacent to the disk portion 45 and a thin, annular tip portion 62b that extends radially outward from the base portion 62a and obliquely toward the flange 31B, and has a truncated cone or cylindrical cone shape.

As shown in Figure 5, the first seal member 30 is positioned so as to cover the second seal member 60 from the radially outer side. Therefore, in use, the second seal member 60 is fixed radially inward of the first seal member 30. Furthermore, the flange 31B of the first seal member 30 faces outboard, and the disc portion 45 of the second seal member 60 faces inboard.

In the operating conditions of the sealing device 21 described below, the side lip 62 is designed so that the tip 62b of the side lip 62 comes into sliding contact with the flange 31B when the sealing device 21 is applied to the object and the side lip 62 is rotating at low speeds (when the rotational speed is below a threshold value). On the other hand, the side lip 62 is designed so that the side lip 62 deforms and the tip 62b of the side lip 62 moves away from the flange 31B when the sealing device 21 is applied to the object and the side lip 62 is rotating at high speeds (when the rotational speed is above a threshold value). However, the side lip 62 is designed so that contact between the tip 62b of the side lip 62 and the flange 31B is maintained even when the sealing device 21 is applied to the object and the side lip 62 is rotating at high speeds.

As shown in Figure 5, in the sealing device 21, an annular gap 54 is provided between the tubular portion 44 of the second seal member 60 and the outer edge 31Bt of the flange 31B of the first seal member 30. In other words, in use, the outboard end 44a of the tubular portion 44 faces the outer edge 31Bt of the flange 31B with a radial gap therebetween, and a gap 54 is formed between the end 44a of the tubular portion 44 and the outer edge 31Bt of the flange 31B. The gap 54 forms a labyrinth seal.

As shown in Figure 5, an annular gap 63 is provided between the disc portion 45 of the second seal member 60 and the sleeve 31A of the first seal member 30. In other words, in use, the outer edge 45a, which is the outer edge of the disc portion 45 of the second seal member 60, faces the inboard portion (portion 31Ap) of the sleeve 31A of the first seal member 30 at a distance in the radial direction, and a gap 63 is formed between the outer edge 45a of the disc portion 45 and portion 31Ap of the sleeve 31A. The gap 63 forms a labyrinth seal.

Next, the operation of the sealing device 21 having the above-described configuration will be explained. The sealing device 21 is attached to an application object and put into use. An application object of the sealing device 21 is, for example, a hub bearing, and the hub bearing to which the sealing device 21 is applied is an inner ring rotating type hub bearing. Figure 6 is a cross-sectional view of a hub bearing 4 to which the sealing device 21 is attached, as an application object of the sealing device 21.

As shown in FIG. 6 , the hub bearing 4 comprises an inner ring 120 and an outer ring 130. Between the inner ring 120 and the outer ring 130, there are a plurality of balls 10 arranged in a row, a plurality of balls 12 arranged in a row, and a plurality of cages 14, 15 that hold the balls in place. The inner ring 120 and the outer ring 130 are provided with the balls 10, 12, which are rolling elements, allowing them to rotate relative to each other coaxially, indicated by the central axis Ax. Specifically, when the hub bearing 4 is mounted on a vehicle or the like, the outer ring 130 is fixed, for example, to the vehicle's suspension system, and the inner ring 120 is rotatable relative to the outer ring 130. The inner ring 120 specifically comprises an inner ring 121 and a hub ring 122. The hub ring 122 has a cylindrical shaft portion 123 extending along the central axis Ax and a hub flange 124. The hub flange 124 is a disk-like portion that extends radially outward from one end on the outboard side of the shaft portion 123, and is the portion to which a wheel (not shown) is attached by a plurality of hub bolts 19. The inner ring 121 is fitted onto the inboard end of the shaft portion 123 of the inner ring 120 to hold the balls 10, 12 in the space between the inner ring 120 and the outer ring 130.

The outer ring 130 has a through-hole 131 extending along the central axis Ax. The shaft 123 of the hub ring 122 of the inner ring 120 and the inner ring 121 are inserted into this through-hole 131, forming an annular space extending along the central axis Ax between the inner ring 121, shaft 123, and the through-hole 131. As described above, the balls 10 and 12 are housed within this space and held by the cages 14 and 15. A lubricant is also applied or injected into the space. A sealing device 21 is attached to the inboard-side opening 126 of the hub bearing 4, where the space between the inner ring 121, shaft 123, and the through-hole 131 forms an opening on the inboard side. Another sealing device 140 is attached to the outboard-side opening 127 of the hub bearing 4, where the space between the inner ring 121, shaft 123, and the through-hole 131 forms an opening on the outboard side. The sealing devices 21 and 140 seal the internal space of the hub bearing 4, preventing lubricant in the internal space from leaking out and preventing foreign matter from entering the internal space from the outside. The sealing device 140 is a conventionally known sealing device, and a detailed description thereof will be omitted. Note that the sealing device 21 can also be used as the sealing device 140. The configuration of the hub bearing to which the sealing device 21 is applied is not limited to the configuration of the hub bearing 4 described above.

Specifically, the sleeve 31A of the first seal member 30 of the sealing device 21 is attached to the inboard cylindrical end 130A of the outer ring 130, and the tubular portion 44 of the second seal member 60 of the sealing device 21 is attached to the inboard cylindrical end 121A of the inner ring 121 of the inner ring 120, and the sealing device 21 is then attached to the hub bearing 4 (see Figure 5). Specifically, the sleeve 31A of the first seal member 30 is interference-fitted to the end 130A of the outer ring 130, and the tubular portion 44 of the second seal member 60 is interference-fitted to the end 121A of the inner ring 121. The axis x of the sealing device 21 attached to the hub bearing 4 coincides or approximately coincides with the central axis Ax of the hub bearing 4.

As described above, the sealing device 21 is fixed to the hub bearing 4. The first seal member 30 is a fixed seal member that is fixed to the stationary outer ring 130 and does not rotate. On the other hand, the second seal member 60 is a rotary seal member that is fixed to the rotating inner ring 120 and rotates. In the hub bearing 4, the sealing device 21 acts differently depending on the rotational speed of the inner ring 120.

Specifically, when the inner ring 120 and second seal member 60 are rotating at low speeds (when the rotational speed is below a threshold), as shown in FIG. 5 , the side lip 62 contacts the flange 31B of the first seal member 30, preventing foreign matter that has entered the space 55 from penetrating further into the internal space of the hub bearing 4. Low-speed rotation includes when the inner ring 120 and second seal member 60 are not rotating. To reduce the torque applied from the flange 31B to the second seal member 60, the side lip 62 may be coated with grease. This grease is typically a different type from the grease that lubricates the balls 10, 12, inner ring 120, and outer ring 130.

On the other hand, when the inner ring 120 and second seal member 60 rotate at high speed (when the rotational speed is greater than the threshold value), as shown by the dotted line in Figure 5, the centrifugal force acting on the side lip 62 itself causes the side lip 62, particularly the tip end 62b, to deform and separate from the flange 31B of the first seal member 30. However, the side lip 62 is designed so that it does not completely separate from the flange 31B due to the centrifugal force acting during this high-speed rotation. Therefore, unlike the sealing device 20, an annular gap is not formed between the tip end 62b of the side lip 62 and the flange 31B when the inner ring 120 and second seal member 60 rotate at high speed. However, the centrifugal force acting on the side lip 62 reduces the interference between the tip end 62b and the flange 31B or the reaction force of the side lip 62. This reduces the sliding resistance between the side lip 62 and the flange 31B when the inner ring 120 rotates at high speed, thereby reducing the torque acting on the rotating inner ring 120. Furthermore, wear of the side lip 62 and an increase in temperature due to frictional heat can be suppressed.

As shown in Figure 5, an annular gap 54 is provided between the end 44a of the tubular portion 44 of the second seal member 60 and the outer edge 31Bt of the flange 31B of the first seal member 30, and the gap 54 functions as a labyrinth seal. This prevents foreign matter from entering the internal space of the hub bearing 4.

Meanwhile, the labyrinth seal formed by the gap 54 prevents the lubricant from leaking out of the internal space of the hub bearing 4, and the side lip 62 prevents the lubricant from leaking out of the hub bearing 4. In this way, the sealing device 21 can prevent the lubricant from leaking out of the internal space of the hub bearing 4 by means of the gap 54 and the side lip 62, regardless of the rotational speed of the inner ring 120.

Also, as shown in FIG. 5, an annular gap 63 is provided between the outer edge 45a of the disc portion 45 of the second seal member 60 and the portion Ap of the sleeve 31A of the first seal member 30, and the gap 63 functions as a labyrinth seal. This prevents foreign matter from entering the internal space 55 of the sealing device 21 from outside the hub bearing 4. In this way, the sealing device 21 can also prevent foreign matter from entering the internal space of the hub bearing 4 by using the gap 63. The gap 63 can also prevent lubricant from leaking out of the hub bearing 4.

As described above, the side lip 62 of the second seal member 60 attached to the rotating inner ring 120 slidably contacts the flange 31B when the rotational speed of the inner ring 120 is lower than a threshold value, thereby ensuring the sealing performance of the sealing device 21. In other words, during low-speed rotation, the side lip 62 prevents foreign matter that has entered the space 55 from entering further into the internal space of the hub bearing 4.

On the other hand, when the rotational speed of the inner ring 120 is greater than the threshold value, the centrifugal force acting on the side lip 62 of the second seal member 60 causes it to deform away from the flange 31B to the extent that contact with the flange 31B is maintained. Therefore, during high-speed rotation, the sealing device 21 reduces the torque acting on the rotating inner ring 120 while maintaining sealing performance, and also suppresses wear of the side lip 62 and temperature increases due to frictional heat.

Next, a sealing device 22 according to a third embodiment of the present invention will be described. The sealing device 22 according to the third embodiment of the present invention differs from the sealing device 20 according to the first embodiment of the present invention in the configuration of the first seal member and the second seal member. Furthermore, the sealing device 22 according to the third embodiment of the present invention is used for an inner ring rotation type application, similar to the sealing device 21 according to the second embodiment of the present invention, and differs from the sealing device 20 described above in the application. Below, with regard to the configuration of the sealing device 22, components that are the same as or have the same functions as the sealing device 20 will be assigned the same reference numerals and their description will be omitted, and only different components will be described.

As shown in FIG. 7, the annular sealing device 22 includes a first seal member 70 that is different from the first seal member 30 of the sealing device 20 described above, and a second seal member 65 that is different from the second seal member 40 of the sealing device 20. The first seal member 70 includes the rigid ring 42 of the second seal member 30 of the sealing device 20 described above and an elastic ring 71. The second seal member 65 includes the rigid ring 31 of the first seal member 30 of the sealing device 20 described above and an elastic ring 66. Note that FIG. 7 only shows one portion of the sealing device 22 relative to the axis x. Also, FIG. 7 shows the sealing device 22 in a state (position) during use, which will be described later.

As shown in Figure 7, the first seal member 70 is positioned so as to cover the second seal member 65 from the radially outer side. Therefore, in use, the second seal member 65 is fixed radially inward of the first seal member 70. Furthermore, the flange 31B of the second seal member 65 faces inboard, and the disc portion 45 of the first seal member 70 faces outboard.

The elastic ring 71 of the first seal member 70 is formed of an elastic material, such as an elastomer. The elastic ring 71 is attached to the rigid ring 42; specifically, the elastic ring 71 is in intimate contact with a portion of the rigid ring 42, and a portion of the rigid ring 42 is embedded in the elastic ring 71. As shown in FIG. 7 , the elastic ring 71 includes a portion of the tubular portion 44 of the elastic ring 41 of the second seal member 40 of the sealing device 20, an inner end portion 72 that is the radially inner end portion of the disc portion 45 of the elastic ring 41 of the second seal member 40, a grease lip 46, and a seal lip 47. The elastic ring 71 also includes the annular portion 49 of the second seal member 40 extending from the inner end portion 72. Like the second seal member 40, the first seal member 70 also includes a garter spring 50.

The grease lip 46 and seal lip 47, like the grease lip 46 and seal lip 47 of the second seal member 40 of the sealing device 20, are disposed radially inward of the disc portion 45 and are formed to slidably contact the sleeve 31A. Specifically, the grease lip 46 extends from the inner end portion 72, and the seal lip 47 is formed on the annular portion 49 extending from the inner end portion 72.

As shown in Figure 7, the elastic ring 71 of the first seal member 70 is not formed in the portion of the disc portion 45 of the first seal member 70 that is radially outward from the inner end portion 72. Therefore, in the disc portion 45 of the first seal member 70, the portion radially outward from the inner end portion 72 of the rigid ring 42 is exposed, and the rigid ring 42 has a contact surface 73, which is an annular surface facing the inboard side, in the portion of the disc portion 45 radially outward from the inner end portion 72.

The elastic ring 66 of the second seal member 65 is formed of an elastic material, such as an elastomer. As shown in Figure 7, the elastic ring 66 is attached to the rigid ring 31. Specifically, the elastic ring 66 is in close contact with a portion of the rigid ring 31, and a portion of the rigid ring 31 is embedded in the elastic ring 66.

As shown in Figure 7, the elastic ring 66 of the second seal member 65 has a base 67, which is attached to the outboard surface of the flange 31B of the rigid ring 31, and a side lip 68 and a labyrinth slip 69, which extend from the base 67. The base 67 extends annularly around the axis x and is formed so as to cover the radially outer end of the flange 31B on the radially outer side.

As shown in Figure 7, the side lip 68 extends from the outboard-facing surface (surface 67a) of the base 67 of the elastic ring 66 and has a shape similar to the side lip 48 of the sealing device 20 described above. It is a thin plate-shaped portion of the elastic ring 66 that extends toward the contact surface 73 of the rigid ring 42 of the first seal member 70. As shown in Figure 7, for example, the side lip 68 has a thick annular base 68a adjacent to the base 67 and a thin annular tip 68b that extends radially outward from the base 68a and obliquely toward the contact surface 73, and has a truncated conical or cylindrical conical shape.

In the operating conditions of the sealing device 22 described below, when the object to which the sealing device 22 is applied and the second seal member 65 are rotating at low speeds (when the rotational speed is below a threshold), the side lip 68 is designed so that its tip 68b slidably contacts the contact surface 73 of the rigid ring 42. On the other hand, when the object to which the sealing device 22 is applied and the second seal member 65 are rotating at high speeds (when the rotational speed is above a threshold), the side lip 68 is designed so that its tip 68b deforms and moves away from the contact surface 73 of the rigid ring 42, similar to the side lip 48 of the sealing device 20 described above. The side lip 68 may also be designed so that when the object to which the sealing device 22 is applied and the second seal member 65 are rotating at high speeds, the tip 68b moves away from the contact surface 73 of the rigid ring 42, but does not move away from the contact surface 73.

Also, as shown in Figure 7, the outer end 67b, which is the portion of the base 67 that covers the radially outer end of the flange 31B of the second seal member 65, faces, with a gap in the radial direction, the labyrinth receiving portion 71a, which is the portion of the elastic ring 71 at the inboard end of the tubular portion 44 of the first seal member 70. Therefore, a gap 74 is formed between the outer end 67b of the base 67 and the labyrinth receiving portion 71a of the tubular portion 44.

As shown in Figure 7, the labyrinth slip 69 extends from the outer end 67b of the base 67 toward the labyrinth receiving portion 71a, and the tip end 69a of the labyrinth slip 69 faces the labyrinth receiving portion 71a with a radial gap therebetween. Thus, in the gap 74, an annular gap 74a is formed between the tip end 69a of the labyrinth slip 69 and the labyrinth receiving portion 71a, further narrowing the gap 74. The gaps 74 and 74a form a labyrinth seal.

Next, the operation of the sealing device 22 having the above-described configuration will be explained. The sealing device 22 is attached to an application object and put into use. An application object of the sealing device 22 is, for example, a hub bearing, and the hub bearing to which the sealing device 22 is applied is an inner ring rotating type hub bearing. The sealing device 22 is attached to, for example, the hub bearing 4 to which the above-described sealing device 21 is attached (see Figure 6). Note that the hub bearing 4 to which the sealing device 22 is attached is not shown in the illustration.

Similar to the sealing device 21, the sealing device 22 is attached to the inboard opening 126 of the hub bearing 4. Specifically, the tubular portion 44 of the first seal member 70 of the sealing device 22 is attached to the inboard end 130A of the outer ring 130, and the sleeve 31A of the second seal member 65 of the sealing device 22 is attached to the inboard end 121A of the inner ring 121 of the inner ring 120, and the sealing device 22 is then attached to the hub bearing 4 (see Figures 6 and 7). Specifically, the tubular portion 44 of the first seal member 70 is interference-fitted to the end 130A of the outer ring 130, and the sleeve 31A of the second seal member 65 is interference-fitted to the end 121A of the inner ring 121. The axis x of the sealing device 22 attached to the hub bearing 4 coincides or approximately coincides with the central axis Ax of the hub bearing 4.

As described above, the sealing device 22 is fixed to the hub bearing 4. The first seal member 70 is a fixed seal member that is fixed to the stationary outer ring 130 and does not rotate. On the other hand, the second seal member 65 is a rotary seal member that is fixed to the rotating inner ring 120. In the hub bearing 4, the sealing device 22 functions differently depending on the rotational speed of the inner ring 120.

Specifically, when the inner ring 120 and second seal member 65 are rotating at low speeds (when the rotational speed is lower than a threshold), as shown in FIG. 7 , the side lip 68 contacts the contact surface 73 of the rigid ring 42 of the first seal member 70, preventing foreign matter that has entered the space 55 from penetrating further into the internal space of the hub bearing 4. Low-speed rotation includes when the inner ring 120 and second seal member 65 are not rotating. To reduce the torque applied to the second seal member 65 from the contact surface 73 of the rigid ring 42, the side lip 68 may be coated with grease. This grease is typically a different type from the grease that lubricates the balls 10, 12, inner ring 120, and outer ring 130.

On the other hand, when the inner ring 120 and second seal member 65 rotate at high speed (when the rotational speed is greater than the threshold value), as shown by the dotted line in Figure 7, the centrifugal force acting on the side lip 68 itself causes the side lip 68, particularly the tip 68a, to deform and move away from the contact surface 73 of the rigid ring 42 of the first seal member 70. Therefore, similar to the sealing device 20, an annular gap 56 is formed between the tip 68a of the side lip 68 and the contact surface 73 of the rigid ring 42 when the inner ring 120 and second seal member 65 rotate at high speed. This eliminates sliding resistance between the side lip 68 and the contact surface 73 of the rigid ring 42 when the inner ring 120 rotates at high speed, thereby reducing the torque applied to the rotating inner ring 120. Furthermore, wear on the side lip 68 and temperature increases due to frictional heat can be suppressed.

Also, as shown in FIG. 7, annular gaps 74, 74a are provided between the labyrinth slip 69 of the second seal member 65 and the labyrinth receiving portion 71a of the tubular portion 44 of the first seal member 70, and the gaps 74, 74a function as a labyrinth seal. This prevents foreign matter from entering the internal space 55 of the sealing device 22 from outside the hub bearing 4. In this way, the sealing device 22 can also prevent foreign matter from entering the internal space of the hub bearing 4 through the gaps 74, 74a. It can also prevent lubricant from leaking to the outside of the hub bearing 4.

The grease lip 46 and seal lip 47 also function in the same manner as the grease lip 46 and seal lip 47 of the sealing device 20 described above. In other words, the grease lip 46 prevents lubricant from leaking from the internal space of the hub bearing 4 to the inboard side. The seal lip 47 also backs up the grease lip 46, preventing lubricant that has passed through the grease lip 46 from leaking from the outboard side to the inboard side.

It is preferable that the grease lip 46 be formed in a shape that can exert a sufficient tightening force (binding force) on the sleeve 31A so that the grease lip 46 does not come off the sleeve 31A when the inner ring 120 of the hub bearing 4 rotates. This prevents the tip of the grease lip 46 from coming off the sleeve 31A when the inner ring 120 of the hub bearing 4 rotates, particularly at high speeds, and suppresses leakage of lubricant from the internal space of the hub bearing 4 to the inboard side.

On the other hand, the tightening force (binding force) of the seal lip 47 to the sleeve 31A is increased by the garter spring 50, so that when the inner ring 120 of the hub bearing 4 rotates, especially at high speeds, the seal lip 47 is prevented from separating from the sleeve 31A, thereby preventing leakage of lubricant to the inboard side.

As described above, the side lip 68 of the second seal member 65 attached to the rotating inner ring 120 slidably contacts the contact surface 73 of the rigid ring 42 when the rotational speed of the inner ring 120 is lower than a threshold value, thereby ensuring the sealing performance of the sealing device 22. In other words, during low-speed rotation, the side lip 68 prevents foreign matter that has entered the space 55 from entering further into the internal space of the hub bearing 4.

On the other hand, when the rotational speed of the inner ring 120 is greater than the threshold value, the side lip 68 of the second seal member 65 is deformed away from the contact surface 73 of the rigid ring 42 due to the centrifugal force acting on the side lip 68 itself. Therefore, during high-speed rotation, the sealing device 22 reduces the torque applied to the rotating inner ring 120 and also suppresses wear of the side lip 68 and temperature increases due to frictional heat.

When the inner ring 120 rotates at high speed, the side lip 68 separates from the contact surface 73 of the rigid ring 42. However, because the second seal member 65 itself is rotating at high speed, an airflow or centrifugal force directed radially outward is generated within the space 55, causing foreign matter that has entered the space 55 to be expelled to the outside through the gaps 74 and 74a. If the labyrinth lip 69 extends obliquely radially outward and inboard as shown in Figure 7, foreign matter that has entered the space 55 can be more easily expelled to the outside through the gaps 74 and 74a, as described above. Furthermore, foreign matter is expelled from the space 57 radially inside the side lip 68 by the airflow or centrifugal force through the gap 56 between the side lip 68 and the contact surface 73 into the space 55, and then further expelled to the outside through the gaps 74 and 74a.

Next, a sealing device 23 according to a fourth embodiment of the present invention will be described. The sealing device 23 according to the fourth embodiment of the present invention differs from the sealing device 22 according to the third embodiment of the present invention in the configuration of the first seal member and the second seal member. Below, with regard to the configuration of the sealing device 23, components that are the same as those of the sealing device 22 or have similar functions will be assigned the same reference numerals and their description will be omitted, and only different components will be described.

As shown in FIG. 8, the annular sealing device 23 includes a first seal member 75 that is different from the first seal member 70 of the sealing device 22 described above, and a second seal member 80 that is different from the second seal member 65 of the sealing device 22 described above. The first seal member 75 includes the rigid ring 42 of the first seal member 70 of the sealing device 22 described above, and an elastic ring 76 that is different from the elastic ring 71 of the first seal member 70. The second seal member 80 includes a rigid ring 81 that is different from the rigid ring 31 of the second seal member 65 of the sealing device 22 described above, and an elastic ring 82 that is different from the elastic ring 66 of the second seal member 65. Note that FIG. 8 only shows one portion of the sealing device 23 relative to the axis x. Also, FIG. 8 shows the sealing device 23 in a state (position) during use, which will be described later.

As shown in Figure 8, the first seal member 75 is positioned so as to cover the second seal member 80 from the radially outer side. Therefore, in use, the second seal member 80 is fixed radially inward of the first seal member 75. Furthermore, the flange 81B (described later) of the second seal member 80 faces the inboard side, and the disc portion 45 of the first seal member 75 faces the outboard side.

As shown in Figure 8, the elastic ring 76 of the first seal member 75 differs from the elastic ring 71 of the first seal member 70 of the sealing device 22 in that it does not have the inner end portion 72, which is part of the disc portion 45, the grease lip 46, or the annular portion 49 on which the seal lip 47 is formed. Therefore, the first seal member 75 does not have a garter spring 50.

The rigid ring 81 of the second seal member 80 is formed from a rigid material, such as metal, and as shown in FIG. 8, has a sleeve 81A that corresponds to the sleeve 31A of the rigid ring 31 of the second seal member 65 of the sealing device 22, and a flange 81B that corresponds to the flange 31B of the rigid ring 31. As shown in FIG. 8, for example, the rigid ring 81 has a shape similar to that of the rigid ring 42, the sleeve 81A has a shape similar to that of the tubular portion 44 of the rigid ring 42, and the flange 81B has a shape similar to that of the disc portion 45 of the rigid ring 42.

The elastic ring 82 of the second seal member 80 is formed of an elastic material, such as an elastomer. As shown in Figure 8, the elastic ring 82 is attached to the rigid ring 81. Specifically, the elastic ring 82 is in close contact with a portion of the rigid ring 81, and a portion of the rigid ring 81 is embedded in the elastic ring 82.

As shown in Figure 8, the elastic ring 82 of the second seal member 80 has a base 83 that is attached to the outboard surface of the flange 81B of the rigid ring 81 and the radially outer surface of the sleeve 81A of the rigid ring 81, and a side lip 68 and a labyrinth slip 69 that extend from the base 83. Furthermore, as shown in Figure 8, the elastic ring 82 has a seal projection 84 that extends from the base 83.

The base 83 extends annularly around the axis x and is formed so as to cover the radially outer end of the flange 81B on the radially outer side, and so as to cover the outboard end of the sleeve 81A on the outboard side.

As shown in Figure 8, the side lip 68 extends from the outboard-facing surface (surface 83a) of the base 83 of the elastic ring 82 and has a shape similar to that of the side lip 68 of the second seal member 65 of the sealing device 22 described above. It is a thin plate-shaped portion of the elastic ring 82 that extends toward the contact surface 73 of the rigid ring 42 of the first seal member 75. As shown in Figure 8, for example, the side lip 68 has a thick annular base portion 68a adjacent to the base 83 and a thin annular tip portion 68b that extends obliquely from the base portion 68a radially outward and toward the contact surface 73 and has a truncated conical or cylindrical conical shape.

In the operating conditions of the sealing device 23 described below, when the object to which the sealing device 23 is applied and the second seal member 80 are rotating at low speeds (when the rotational speed is below a threshold), the side lip 68 is designed so that the tip 68b of the side lip 68 slidably contacts the contact surface 73 of the rigid ring 42. On the other hand, when the object to which the sealing device 23 is applied and the second seal member 80 are rotating at high speeds (when the rotational speed is above a threshold), the side lip 68 is designed so that the tip 68b of the side lip 68 deforms and moves away from the contact surface 73 of the rigid ring 42, similar to the side lip 68 of the sealing device 22 described above. The side lip 68 may also be designed so that the tip 68b moves away from the contact surface 73 of the rigid ring 42, but does not move away from the contact surface 73, when the object to which the sealing device 23 is applied and the second seal member 80 are rotating at high speeds.

Also, as shown in Figure 8, the outer end 83b, which is the portion of the base 83 that covers the radially outer end of the flange 81B of the second seal member 80, faces the labyrinth receiving portion 71a of the elastic ring 76 of the tubular portion 44 of the first seal member 75 at a radial distance. Therefore, a gap 74 is formed between the outer end 83b of the base 83 and the labyrinth receiving portion 71a of the tubular portion 44.

As shown in Figure 8, the labyrinth slip 69 extends from the outer end 83b of the base 83 toward the labyrinth receiving portion 71a, and the tip end 69a of the labyrinth slip 69 faces the labyrinth receiving portion 71a with a radial gap therebetween. Thus, in the gap 74, an annular gap 74a is formed between the tip end 69a of the labyrinth slip 69 and the labyrinth receiving portion 71a, further narrowing the gap 74. The gaps 74 and 74a form a labyrinth seal.

The seal projection 84 is an annular portion around the axis x. As shown in FIG. 8, the seal projection 84 extends from the outboard end 83c, which is the portion of the base 83 that covers the outboard end of the sleeve 81A. The seal projection 84 extends from the outboard end 83c toward the inner edge 45b, which is the radially inner edge of the disc portion 45 of the rigid ring 42 of the first seal member 75. As shown in FIG. 8, the inner edge 45b of the rigid ring 42 is located, for example, radially outward and outboard relative to the outboard end 83c of the base 83. The seal projection 84 extends obliquely from the outboard end 83c radially outward and outboard. The seal projection 84 is shaped so that its tip portion (tip 84a) contacts the inner edge 45b of the rigid ring 42.

Next, the operation of the sealing device 23 having the above-described configuration will be explained. The sealing device 23 is attached to an application and put into use. An application of the sealing device 23 is, for example, a hub bearing, and the hub bearing to which the sealing device 23 is applied is an inner ring rotating type hub bearing. The sealing device 23 is attached to the hub bearing 4 to which the above-described sealing device 21 is attached, for example, in the same way as the sealing device 22 (see Figure 6). Note that the hub bearing 4 to which the sealing device 23 is attached is not shown in the illustration.

Like the sealing device 22, the sealing device 23 is attached to the inboard opening 126 of the hub bearing 4. Specifically, the tubular portion 44 of the first seal member 75 of the sealing device 23 is attached to the inboard end 130A of the outer ring 130, and the sleeve 81A of the second seal member 80 of the sealing device 23 is attached to the inboard end 121A of the inner ring 121 of the inner ring 120, and the sealing device 23 is then attached to the hub bearing 4 (see Figures 6 and 8). Specifically, the tubular portion 44 of the first seal member 75 is interference-fitted to the end 130A of the outer ring 130, and the sleeve 81A of the second seal member 80 is interference-fitted to the end 121A of the inner ring 121. The axis x of the sealing device 23 attached to the hub bearing 4 coincides or approximately coincides with the central axis Ax of the hub bearing 4.

As described above, the sealing device 23 is fixed to the hub bearing 4. The first seal member 75 is a fixed seal member that is fixed to the stationary outer ring 130 and does not rotate. On the other hand, the second seal member 80 is a rotary seal member that is fixed to the rotating inner ring 120. In the hub bearing 4, the sealing device 23 functions differently depending on the rotational speed of the inner ring 120.

Specifically, as shown in FIG. 8 , when the inner ring 120 and second seal member 80 are rotating at low speeds (when the rotational speed is lower than a threshold), the side lip 68 acts similarly to the side lip 68 of the sealing device 22, contacting the contact surface 73 of the rigid ring 42 of the first seal member 75 and preventing foreign matter that has entered the space 55 from penetrating further into the internal space of the hub bearing 4. Low-speed rotation includes when the inner ring 120 and second seal member 80 are not rotating. To reduce the torque applied to the second seal member 80 from the contact surface 73 of the rigid ring 42, the side lip 68 may be coated with grease. This grease is typically different from the grease that lubricates the balls 10, 12, inner ring 120, and outer ring 130.

On the other hand, when the inner ring 120 and second seal member 80 rotate at high speeds (when the rotational speed is greater than the threshold value), as shown by the dotted line in Figure 8, the side lip 68, particularly the tip 68b, acts in the same manner as the side lip 68 of the sealing device 22, and the centrifugal force acting on the side lip 68 itself causes it to deform away from the contact surface 73 of the rigid ring 42 of the first seal member 75. Therefore, similar to the sealing device 22, an annular gap 56 is formed between the tip 68b of the side lip 68 and the contact surface 73 of the rigid ring 42 when the inner ring 120 and second seal member 80 rotate at high speeds. This eliminates sliding resistance between the side lip 68 and the contact surface 73 when the inner ring 120 rotates at high speeds, thereby reducing the torque applied to the rotating inner ring 120. Furthermore, wear on the side lip 68 and temperature increases due to frictional heat can be suppressed.

Also, as shown in FIG. 8, annular gaps 74, 74a are provided between the labyrinth slip 69 of the second seal member 80 and the labyrinth receiving portion 71a of the tubular portion 44 of the first seal member 75. Similar to the gaps 74, 74a of the sealing device 22, the gaps 74, 74a function as labyrinth seals. This prevents foreign matter from entering the internal space 55 of the sealing device 23 from outside the hub bearing 4. In this way, the sealing device 23 can also prevent foreign matter from entering the internal space of the hub bearing 4 through the gaps 74, 74a. It can also prevent lubricant from leaking to the outside of the hub bearing 4.

The tip 84a of the seal projection 84 contacts the inner edge 45b of the rigid ring 42 of the first seal member 75, and the seal projection 84 fills the annular gap between the inner edge 45b of the rigid ring 42 of the first seal member 75 and the outboard end 83c of the elastic ring 82 of the second seal member 80. Therefore, the seal projection 84 prevents lubricant from leaking from the internal space of the hub bearing 4 to the inboard side. The seal projection 84 also prevents foreign matter from entering the internal space of the hub bearing 4.

The tip 84a of the seal projection 84 contacts the inner edge 45b of the rigid ring 42 from the radially inner side. Therefore, when centrifugal force is applied to the seal projection 84 due to rotation of the inner ring 120 of the hub bearing 4, this centrifugal force presses the tip 84a of the seal projection 84 further against the inner edge 45b of the rigid ring 42. This prevents the tip 84a of the seal projection 84 from separating from the inner edge 45b of the rigid ring 42 when the inner ring 120 of the hub bearing 4 rotates, particularly at high speeds, further suppressing leakage of lubricant from the internal space of the hub bearing 4 to the inboard side.

As described above, the side lip 68 of the second seal member 80 attached to the rotating inner ring 120 slidably contacts the contact surface 73 of the rigid ring 42 when the rotational speed of the inner ring 120 is lower than a threshold value, thereby ensuring the sealing performance of the sealing device 23. In other words, during low-speed rotation, the side lip 68 prevents foreign matter that has entered the space 55 from entering further into the internal space of the hub bearing 4.

On the other hand, when the rotational speed of the inner ring 120 is greater than the threshold value, the centrifugal force acting on the side lip 68 of the second seal member 80 causes the side lip 68 to deform away from the contact surface 73 of the rigid ring 42. Therefore, during high-speed rotation, the sealing device 23 reduces the torque applied to the rotating inner ring 120 and suppresses wear of the side lip 68 and temperature increases due to frictional heat.

When the inner ring 120 rotates at high speed, the side lip 68 separates from the contact surface 73 of the rigid ring 42. However, because the second seal member 80 itself is rotating at high speed, an airflow or centrifugal force directed radially outward is generated within the space 55, causing foreign matter that has entered the space 55 to be expelled to the outside through the gaps 74 and 74a. If the labyrinth lip 69 extends obliquely radially outward and inboard as shown in Figure 8, foreign matter that has entered the space 55 can be more easily expelled to the outside through the gaps 74 and 74a, as described above. Furthermore, foreign matter is expelled from the space 57 radially inside the side lip 68 by the airflow or centrifugal force through the gap 56 between the side lip 68 and the contact surface 73 into the space 55, and then further expelled to the outside through the gaps 74 and 74a.

The threshold rotational speed during high-speed rotation of the hub bearings 1, 3, 4 at which the side lips 48, 62, 68 respectively deform can be adjusted, for example, by the shape of the base portions 51, 62a, 68a and tip portions 52, 62b, 68b of the side lips 48, 62, 68, and the properties of the elastic material of the elastic rings 41, 61, 66, 82. The shapes of the base portions 51, 62a, 68a and tip portions 52, 62b, 68b include, for example, the thickness and hardness of the base portions 51, 62a, 68a and tip portions 52, 62b, 68b. The properties of the elastic material include, for example, the elastic modulus of the elastic material. In addition, the threshold rotational speed during high-speed rotation of the hub bearings 1, 3, 4 at which the side lips 48, 62, 68, respectively, deform can also be adjusted by the distance (spacing) between the first seal member 30, 70, 75 and the second seal member 40, 60, 65, 80 in the direction of the central axis Ax.

While the present invention has been shown and described with reference to preferred embodiments thereof, those skilled in the art will recognize that changes in form and detail may be made therein without departing from the scope of the invention as set forth in the claims. Such changes, modifications, and alterations are intended to be included within the scope of the invention.

For example, multiple side lips may be provided.

A protrusion may be provided in the space 55 to reduce the intrusion of foreign matter toward the side lip 48, 62, 68. The protrusion may be formed on the first seal member 30, 70, 75 or the second seal member 40, 60, 65.

1, 3, 4...hub bearing, 2...hole, 6, 120...inner ring (inner member), 8, 130...outer ring (outer member), 20, 21, 22, 23...sealing device, 30, 70, 75...first seal member, 31, 81...rigid ring, 31A, 81A...sleeve, 31Ap...portion, 31B, 81B...flange, 31Bt...outer edge, 40, 60, 65, 80...second seal member, 41, 61, 66, 82...elastic ring, 4 2...rigid ring, 44...tubular portion, 44a...end portion, 45...disk portion, 45a...outer end edge, 45b...inner end edge, 46...grease lip (radial lip), 47...seal lip (radial lip), 48, 62, 68...side lip, 49...annular portion, 50...garter spring, 51, 62a, 68a...base portion, 52, 62b, 68b...tip portion, 54, 63, 74, 74a...gap, 67, 83...base portion, 67 a, 83a...surface, 67b, 83b...outer end, 69...labyrinth slip, 69a...tip portion, 71, 76...elastic ring, 71a...labyrinth receiving portion, 72...inner end, 73...contact surface, 83c...outboard side end, 84...seal projection, 84a...tip portion, 100...in-wheel motor unit, 101...outer casing, 101a...end, 101b...mounting surface, 102...inner casing, 102a...cylinder portion, 102b...disc portion, 102c...mounting surface, 103...motor generator, 104...rotor, 105...stator, 110...brake disc, 121...inner ring, 121A...end portion, 122...hub ring, 123...shaft portion, 124...hub flange, 126...inboard side opening, 127...outboard side opening, 130A...end portion, 131...through hole, 140...other sealing device, Ax...central axis, x...axis

Claims (9)

A sealing device disposed between a fixed inner member and a rotating outer member to seal a gap between the inner member and the outer member, comprising:
a first seal member having a sleeve attached to the inner member and a flange extending radially outward from the sleeve;
a second seal member including a tubular portion disposed radially outward of the flange and attached to the outer member, a disc portion extending radially inward from the tubular portion and facing the flange, a radial lip disposed radially inward of the disc portion and in slidable contact with the sleeve, and a side lip extending from the disc portion toward the flange,
the side lip of the second seal member slidably contacts the flange when the rotational speed of the outer member is less than a threshold value, and deforms to move away from the flange when the rotational speed of the outer member is greater than a threshold value;
the tubular portion and the flange form an annular gap on a side farther from the sealed space of the gap between the inner member and the outer member than the side lip,
A sealing device characterized in that the gap formed by the tubular portion and the flange allows foreign matter to be discharged to the outside through the gap formed by the tubular portion and the flange . A sealing device disposed between a rotating inner member and a fixed outer member to seal a gap between the inner member and the outer member, comprising:
a first seal member attached to the outer member;
a second seal member attached to the inner member;
The first seal member has a first rigid ring that is an annular member around an axis formed from a rigid material,
the second seal member has a second rigid ring which is an annular member around the axis and is made of a rigid material, and a second elastic ring which is an annular member around the axis and is made of an elastic material,
the second elastic ring of the second seal member has a side lip that is an annular portion around the axis line and extends along the axis line,
the first rigid ring of the first seal member is adapted to be in contact with a tip end of the side lip,
the side lip of the second seal member slidably contacts the first rigid ring of the first seal member when the rotational speed of the inner member is less than a threshold value, and deforms to move in a direction away from the first rigid ring of the first seal member when the rotational speed of the inner member is greater than a threshold value;
the first seal member and the second seal member form an annular first gap on a side of the side lip that is closer to the sealed space of the gap between the inner member and the outer member,
the second elastic ring has an annular sealing protrusion around the axis that closes the first gap,
A sealing device characterized in that the seal projection protrudes along the axis and is formed to contact the radially inner edge of the first rigid ring from the axis side. A sealing device disposed between a rotating inner member and a fixed outer member to seal a gap between the inner member and the outer member, comprising:
a first seal member attached to the outer member;
a second seal member attached to the inner member;
The first seal member has a first rigid ring that is an annular member around an axis formed from a rigid material,
the second seal member has a second rigid ring which is an annular member around the axis and is made of a rigid material, and a second elastic ring which is an annular member around the axis and is made of an elastic material,
the second elastic ring of the second seal member has a side lip that is an annular portion around the axis line and extends along the axis line,
the first rigid ring of the first seal member is adapted to be in contact with a tip end of the side lip,
the side lip of the second seal member slidably contacts the first rigid ring of the first seal member when the rotational speed of the inner member is less than a threshold value, and deforms to move in a direction away from the first rigid ring of the first seal member when the rotational speed of the inner member is greater than a threshold value;
the first seal member and the second seal member form an annular first gap on a side of the side lip that is closer to the sealed space of the gap between the inner member and the outer member,
the first seal member has a first elastic ring that is an annular member around the axis and is made of an elastic material;
the first elastic ring has an annular seal lip around the axis that closes the first gap,
A sealing device characterized in that a garter spring is wound around the outer periphery of the seal lip. A sealing device as described in claim 2 or 3, characterized in that the side lip of the second seal member deforms away from the first rigid ring of the first seal member when the rotational speed of the inner member is greater than a threshold value. A sealing device as described in any one of claims 2 to 4, characterized in that a second annular gap is formed on the side of the side lip that is farther from the sealed space in the gap between the inner member and the outer member. A sealing device as described in claim 5, characterized in that the second elastic ring has a labyrinth slip, which is an annular portion around the axis that protrudes toward the second gap and forms a labyrinth seal. The sealing device described in claim 5, wherein the second gap forms a labyrinth seal. A sealing device as described in claim 1, wherein a garter spring is wound around the outer periphery of the radial lip. The sealing device according to claim 6, wherein the labyrinth slip extends radially outward and obliquely in the axial direction toward a side away from the sealed space of the gap between the inner member and the outer member.