WO2008018764A1

WO2008018764A1 - Seal integrated with encoder

Info

Publication number: WO2008018764A1
Application number: PCT/KR2007/003831
Authority: WO
Inventors: Jong Soon Im; Ji Hun Park; Min Chul Park; Young Tae Kim
Original assignee: Iljin Global Co Ltd
Current assignee: Iljin Global Co Ltd
Priority date: 2006-08-09
Filing date: 2007-08-09
Publication date: 2008-02-14
Anticipated expiration: 2009-02-09
Also published as: KR100799643B1

Abstract

An encoder- integrated seal includes: a seal support 141 having a first cylindrical portion 141a mounted on the stationary ring; a slinger 147 having a first radial portion 147b spaced away from the seal support 141 outwardly and formed in the radial direction, a second radial portion 147c extending from the first radial portion 147b, and a second cylindrical portion 147 a extending directly from an end of the first radial portion in the axial direction; an elastic part 143 attached to the seal support 141; seal lips 145a, 145b and 145c extending from the elastic part 143; and an encoder 149 attached to at least one side of the first radial portion 147b and the second radial portion 147c. The second radial portion 147c is slanted into the opening, and a second cylindrical portion 147a is mounted on the rotary ring.

Description

Description SEAL INTEGRATED WITH ENCODER

Technical Field

[1] The present invention generally relates to an encoder-integrated seal, and more particularly to an encoder-integrated seal capable of detecting a magnetic field even when there is a mounting error of a sensor in a radial direction. The present invention also relates to an encoder-integrated seal that includes a slinger with a simple configuration to allow easy manufacture without any substantial manufacturing errors, to occupy less space and to improve sensitivity. Background Art

[2] Recently, a bearing for car suspensions has been equipped with an encoder- integrated seal. With this configuration, it is possible to control an anti-lock braking system (ABS) or a traction control system (TCS) by detecting a rotational speed of the bearing based on the change of a magnetic field generated from the encoder. Generally, the encoder has a ring shape and includes permanent magnets, of which N- poles and S -poles are alternately located at predetermined intervals in a circumferential direction. When the encoder is rotated, a magnetic field varies at a predetermined period, which is detected by a hall sensor, a magneto-resistive sensor, etc.

[3] Fig. 1 is a cross-sectional view of one example of a wheel bearing having a conventional encoder-integrated seal. Fig. 2 is an enlarged cross-sectional view of Part ¹A¹ in Fig. 1. Fig. 3 is an enlarged cross-sectional view of the encoder- integrated seal of Fig. 2. Fig. 4 is an enlarged cross-sectional view of another conventional encoder- integrated seal. Fig. 5 is an enlarged cross-sectional view of yet another conventional encoder-integrated seal.

[4] Referring to Figs. 1 and 2, a bearing 1 having an encoder-integrated seal includes an outer ring 20 having at least one outer ring race 21, an inner ring 10 having at least one inner ring race 11 , a plurality of rolling elements 30 disposed between the inner ring race 11 and the outer ring race 21, and a seal 40 sealing an opening between the inner ring 10 and the outer ring 20.

[5] A spline is located on an inner periphery 73 of a hub 70 and a seat 77 is formed at one side of an outer periphery thereof. The hub 70 includes a flange 75 having at least one hole 75a, into which a securing bolt 80 is inserted. A car wheel (not shown) is mounted on the securing bolt 80. In Fig. 1, a single inner ring 10 is mounted on the seat 77. However, the seat 77 may extend to the flange 75 such that a pair of inner rings 10 can be mounted thereon.

[6] A knuckle flange 25 is formed on an outer periphery of the outer ring 20 to fix a knuckle join (not shown) such that the knuckle joint can be connected to a suspension. A molding part 71 is formed to maintain the inner ring 10 on the seat 77 of the hub 70 and to apply preload to the bearing. A seal 90 is formed between the outer ring 20 and the hub 70 to seal the opening therebetween.

[7] Referring to Figs. 2 and 3, the seal 40 disposed in the opening between the inner ring 10 and the outer ring 20 includes: a seal support 41 comprising a first cylindrical portion 41a inserted into the inner periphery 23 of the outer ring 20; a ring-shaped portion 41b extending perpendicularly from the first cylindrical portion 41a in the radial direction; a slinger 47 comprising a second cylindrical portion 47a inserted into an outer periphery 13 of the inner ring 10 and a radial portion 47b extending perpendicularly from the second cylindrical portion 47a in the radial direction; an elastic part 43 attached to the seal support 41 toward the slinger 47; an encoder 49 mounted on an outer side of the slinger 47; and a plurality of seal lips 45a, 45b and 45c extending from the elastic part 43 and contacting an opposite side of the slinger 47 to the encoder 39. In Fig. 2, a dotted line indicates a sensor 1000 for detecting the rotation of the bearing in association with the encoder 49.

[8] An outer surface 49a of the encoder 49 attached to the outer side of the slinger 47 is coplanar with a terminal surface 25 of the outer ring 20 and a terminal surface 15 of the inner ring 10.

[9] In such a conventional encoder- integrated seal 40, the encoder 49 has a fan shape centered on a rotational axis of the bearing. As such, since the width of the encoder 49 decreases toward the rotational axis, the width of the encoder 49 narrows down in the circumferential direction. As a result, depending on a mounting location of the sensor 1000 provided in the radial direction as indicated by the arrow in Fig. 2, the intensity of magnetic force applied to the sensor 1000 varies. In other words, if the sensor 1000 is not installed at a proper position, then the sensitivity of the sensor 1000 deteriorates so that the sensor 1000 inaccurately detects the rotation of the bearing 1 or fails to detect the rotation thereof.

[10] Fig. 4 shows a seal designed to solve the foregoing problems. In this seal, a slinger

47 comprises: a first radial portion 47b extending from a second cylindrical portion 47a in the radial direction; and a second radial portion 47c stepped at a predetermined gap (G) from the first radial portion 47b to an outside of the bearing (to the right side in Fig. 4). The encoder 49 is attached to outer surfaces of the first radial portion 47b and the second radial portion 47c. An outer surface 49a of the encoder 49 attached to the outer surfaces of the first and second radial portions 47b and 47c is coplanar with the terminal surface 25 of the outer ring 20 and the terminal surface 15 of the inner ring 10 shown in Fig. 2. Thus, a portion of the encoder 49 attached to the first radial portion 47b has an increased thickness by the gap (G) in a direction of the rotational axis than that of a portion of the encoder 49 attached to the second radial direction 47c, thereby counterbalancing a decrease in magnetic force due to a decrease in area.

[11] In such a conventional encoder- integrated seal 40, however, since an inner periphery 49b of the encoder 49 with a minimum area must have a predetermined thickness, the gap (G) becomes larger than is actually needed. Furthermore, the complicated shape of the slinger 47 formed by bending at least three times makes it difficult to manufacture the slinger 47 and increases the possibility of errors in manufacturing thereof. Moreover, the shape of the slinger 47 for generating a uniform magnetic force in the radial direction (i.e., the position of a step or the gap (G) of the step) is not standardized.

[12] Fig. 5 shows a seal designed to solve the foregoing problems. In this seal, a slinger

47 comprises a curved radial portion 47b extending radially from a second cylindrical portion 47a, and an encoder 49 is attached to an outer surface of the radial portion 47b. An outer surface 49a of the encoder 49 attached to the outer surface of the radial portion 47b is coplanar with the terminal surface 25 of the outer ring 20 and the terminal surface 15 of the inner ring 10 shown in Fig. 2, or is separated at a predetermined gap therefrom.

[13] In other words, the encoder-integrated seal 40 of Fig. 5 has the radial portion 47b of the slinger 47 formed in a curved plane to maintain a constant magnetic force in the radial direction. However, it is substantially very difficult to form the radial direction in a curved plane. Moreover, this configuration is likely to suffer from manufacturing errors. Accordingly, manufacturing costs are significantly increased in order to make the encoder-integrated seal 40 capable of providing the constant magnetic force. Disclosure of Invention Technical Problem

[14] The present invention relates to solving the foregoing problems of the prior art. An aspect of the present invention is to provide an encoder- integrated seal, which can maintain a magnetic force from an encoder over a certain level in a radial direction and has a simple configuration to allow easy manufacture without any substantial manufacturing errors. Technical Solution

[15] According to an aspect of the present invention, there is provided an encoder- integrated seal mounted on a bearing including a rotary ring, a stationary ring, and a plurality of rolling elements disposed between the rotary ring and the stationary ring to be located in an opening defined between the rotary ring and the stationary ring and facing the rolling elements, including: a seal support having a first cylindrical portion mounted on the stationary ring; a slinger having a first radial portion spaced away from the seal support outwardly and formed in a radial direction, a second radial portion extending from the first radial portion and slanted into the opening, and a second cylindrical portion extending directly from an end of the first or second radial portion in an axial direction and mounted on the rotary ring; an elastic part attached to the seal support or the slinger; at least one seal lip extending from the elastic part and contacting one side of the slinger or the seal support; and an encoder attached to at least one portion of each of the first and second radial portions.

[16] Preferably, the second radial portion has an inclined angle in the range of 15-25 degrees with respect to the first radial portion.

[17] A height of the first radial portion in the radial direction may be within 55% to 65% of a height of the slinger in the radial direction. Further, a height of the second radial portion in the radial direction may be within 35% to 45% of the height of the slinger in the radial direction.

[18] The encoder attached to the at least one portion of each of the first and second radial portions may have an outer surface slanted in the radial direction to have a gradually increasing thickness in an axial direction toward a center of a rotational axis. Also, the outer surface of the encoder may have an inclined angle in the range of 1~5 degrees in the radial direction.

[19] According to another aspect of the invention, there is provided an encoder- integrated seal mounted on a bearing including a rotary ring, a stationary ring, and a plurality of rolling elements between the rotary ring and the stationary ring to be disposed in an opening defined between the rotary ring and the stationary ring and facing the rolling elements, including: a seal support having a first cylindrical portion inserted into the stationary ring; a slinger having a second cylindrical portion inserted into the rotary ring and a radial portion extending from the second cylindrical portion in a radial direction; an elastic part attached to the seal support or the slinger; at least one seal lip extending from the elastic part and contacting one side of the slinger or the seal support; and an encoder attached to an outer side of the radial portion and having an outer surface slanted to have a gradually increasing thickness toward a center of a rotational axis in the radial direction. Preferably, the outer surface of the encoder has an inclined angle in the range of 1~5 degrees.

Advantageous Effects

[20] The encoder-integrated seal 140 for a bearing 100 according to the present invention allows a sensor 1000, which is provided for detecting an magnetic field from an encoder, to detect a magnetic force even though the sensor 1000 is erroneously located in the radial direction, thereby lowering deviations in sensitivity of the sensor caused by positional errors of the encoder and sensor. Accordingly, it is possible to reduce time and problems for installing the sensor 1000. On the other hand, since the seal includes a slinger 147 constituted by a first cylindrical portion 147a mounted on a rotary ring, a first radial portion 147b in the radial direction and a second radial portion 147c slanted at a predetermined angle to the first radial portion 147b, the slinger 147 can be easily manufactured. As a result, the slinger 147 of the present invention can significantly reduce manufacturing errors. Further, since an inclined angle (θ ) is small, the volume of the seal 140 occupying in the bearing decreases. In particular, the encoder 149 has an outer surface 149a slanted in the axial direction such that the distance between the sensor 1000 and the encoder gradually decreases toward the center of the rotational axis, thereby significantly reducing variation of magnetic force due to mounting errors of the sensor 1000 in the radial direction. Brief Description of the Drawings

[21] Fig. 1 is a cross-sectional view of one example of a wheel bearing having a conventional encoder-integrated seal;

[22] Fig. 2 is an enlarged cross-sectional view of Part 'A' in Fig. 1 ;

[23] Fig. 3 is an enlarged cross-sectional view of the encoder-integrated seal of Fig. 2;

[24] Fig. 4 is an enlarged cross-sectional view of another conventional encoder- integrated seal;

[25] Fig. 5 is an enlarged cross-sectional view of yet another conventional encoder- integrated seal;

[26] Figs. 6 and 7 are partially cross- sectional views of a mounting state of an encoder- integrated seal according to one embodiment of the present invention;

[27] Fig. 8 is a cross-sectional view of the encoder-integrated seal of Fig. 6; and

[28] Fig. 9 is a cross-sectional view of an encoder-integrated seal according to another embodiment of the present invention. Best Mode for Carrying Out the Invention

[29] Exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In describing an encoder-integrated seal according to the present invention, like terms as those of a conventional technique will be used to designate like components. Thus, repetitious descriptions will be omitted.

[30] Figs. 6 and 7 are partially cross- sectional views of a mounting state of an encoder- integrated seal according to one embodiment of the present invention. Fig. 8 is a cross- sectional view of the encoder-integrated seal of Fig. 6. Specifically, Fig. 6 is a partially enlarged cross- sectional view of a bearing 100 including a rotary inner ring 110 and a stationary outer ring 120. Further, Fig. 7 is a partially enlarged cross-sectional view of another bearing 100 including a stationary inner ring 110 and a rotary outer ring 120.

[31] First, an encoder- integrated seal 140 for the bearing 100 including the rotary inner ring 110 and the stationary outer ring 120 will be described.

[32] Referring to Fig. 6, according to one embodiment of the present invention, the bearing 100 includes the rotary inner ring 110 having an inner ring race 111 formed therein, the stationary outer ring 120 having an outer ring race 121 formed thereon, and a rolling element 130 disposed between the inner ring race 111 and the outer ring race 121. The seal 140 is mounted in an opening formed between the inner ring 110 and the outer ring 120 to communicate with the rolling element 130.

[33] Referring to Figs. 6 to 8, the seal 140 according to this embodiment includes: a seal support 141 having a first cylindrical portion 141a mounted on an inner periphery 123 of the outer ring 120 and a ring-shaped portion 141b extending from the first cylindrical portion 141a in the radial direction; a slinger 147 having a second cylindrical portion 147a mounted on an outer periphery 113 of the inner ring 110, a first radial portion 147b extending directly from the second cylindrical portion 147 a in the radial direction, and a second radial portion 147c extending directly from the first radial portion 147b and slanted at a predetermined angle into the opening with respect to the first radial portion 147b; an elastic part 143 attached to the seal support 141 toward the slinger 147; an encoder 149 attached to an outer side of the slinger 147; and a plurality of seal lips 145a, 145b and 145c extending from the elastic part 143 and contacting an opposite side of the slinger 147 to the encoder 149.

[34] The second radial portion 147c is slanted at a predetermined angle(θ ) into the opening with respect to the first radial portion 147b in the radial direction. As such, with the second radial portion 147c slanted with respect to the first radial portion 147b, the encoder 149 has a gradually increasing thickness toward the center of a rotational axis on the outer side of the first radial portion 147b and the second radial portion 147c. Accordingly, a gradual decrease in magnetic force toward the center of the rotational axis is counterbalanced by a gradual increase in thickness of the encoder 149 in the axial direction.

[35] In order to keep a constant magnetic force from the encoder 149, the inclined angle of the first radial portion 147c with respect to the first radial part 147b is preferably in the range of 15-25 degrees, and more preferably 20 degrees. When the second radial portion 147c is formed to have the inclined angle as described above, a sensor 1000 can detect a predetermined magnetic force regardless of its position in the radial direction. Due to the slanted second radial portion 147c, the seal 140 has a significantly smaller volume than that of the conventional seal shown in Fig. 4.

[36] In forming the first and second radial portions 147b and 147c, even when the encoder 149 has a constant thickness to a predetermined portion toward the first cylindrical portion 141a of the seal support 141, a magnetic force does not decrease as much as the sensor 1000 cannot detect the magnetic force due to a decrease in width of the encoder 149 in the circumferential direction. Thus, a height (H ) of the first radial portion 147b in the radial direction is preferably within 35-45% of the total height (H) of the slinger 147. Also, a height (H ) of the second radial portion 147c in the radial direction is preferably within 55% to 65% of the total height (H) of the slinger 147.

[37] If the height (H ) of the second radial portion 147b is 55% or less, then the magnetic force from the encoder 149 weakens near the boundary between the first radial portion 147b and the second radial portion 147c. Thus, since it is necessary to increase the overall thickness of the encoder 149 attached to the first radial portion 147c, the thickness of the seal 140 becomes increased at a portion occupied by the encoder 149.

[38] On the other hand, if the height (H ) of the second radial portion 147c is 65% or more, then a portion of the encoder 149 attached to the second radial portion 147c increases in volume than is actually needed.

[39] The encoder 149 attached to at least one portion of each of the first radial portion

147b and the second radial portion 147c may have an outer surface 149a slanted at a predetermined angle (θ ) outwardly with respect to the opening. When defining the angle (θ ), it is desirable that the encoder 149 approaches the sensor 1000 with a decrease in distance to the second cylindrical portion 147a. The angle (θ ) is preferably in the range of 1~5 degrees. With such an inclined angle (θ ) as described above, it is possible to further reduce the effect of the decrease in volume of the encoder 149. Mode for the Invention

[40] Referring to Fig. 7, for the bearing including the stationary inner ring 110 and the rotary outer ring 120, an encoder-integrated seal 140 according to one embodiment of the present invention includes: a seal support 141 having a first cylindrical portion 141a mounted on an outer periphery 113 of the inner ring 110 and a ring-shaped portion 141b extending from the first cylindrical portion 141a in the radial direction; a slinger 147 having a first radial portion 147b spaced away from the seal support 141 outward the opening and formed in the radial direction, a second radial portion 147c extending from the first radial portion 147b and inclined toward the center of the rotational axis, and a second cylindrical portion 147a extending directly from the second radial portion 147c and mounted on the inner periphery 123 of the outer ring 120; an elastic part 143 attached to the seal support 141 toward the slinger 147; an encoder 149 provided at an outer side of the slinger 147; and a plurality of seal lips 145a, 145b and 145c extending from the elastic part 143 and contacting an opposite side of the slinger 147 to the encoder 149.

[41] The second radial portion 147c is slanted at a predetermined angle (θ ) with respect to the first radial portion 147b. Therefore, the encoder 149 attached to at least one outer portion of each of the first radial portion 147b and the second radial portion 147c has an increasing thickness toward the center of the rotational axis. Accordingly, a decrease in magnetic force due to a decreasing width of the encoder 149 in the circumferential direction is counterbalanced by an increase in thickness of the encoder 149.

[42] The inclined angle (θ ) of the second radial portion 147c with respect to the first radial portion 147b, the height (H ) of the first radial portion 147b, and the height (H ) of the second radial portion 147c are similar to those in the aforementioned description. Thus, descriptions thereof will be omitted herein.

[43] Fig. 9 is a cross-sectional view of an encoder-integrated seal 150 having improved sensitivity according to another embodiment of the present invention. Referring to Fig. 9, the encoder- integrated seal 150 includes: a seal support 141 having a first cylindrical portion 141a mounted on the inner periphery 123 of the outer ring 120 and a ring- shaped portion 141b extending from the first cylindrical portion 141a in the radial direction; a slinger 147 having a second cylindrical portion 147a mounted on the outer periphery 113 of the inner ring 110 and a radial portion 147b extending from the second cylindrical portion 147a in the radial direction; an elastic part 143 attached to the seal support 141 toward the slinger 147; an encoder 149 attached to an outer side of the radial portion 147b and having an outer surface slanted in the radial direction so as to have an increasing thickness toward the center of the rotational axis; and a plurality of seal lips 145a, 145b and 145c extending from the elastic part 143 and contacting an opposite side of the slinger 147 to the encoder 149.

[44] The encoder 149 has an outer surface 149a slanted at a certain angle(θ ) outward the opening in the radial direction. In order to keep a constant magnetic force from the encoder 149 regardless of mounting errors of the sensor 1000 in the radial direction, the inclined angle (θ ) of the outer surface 149a is preferably in the range of 15-25 degrees.

[45] When the outer surface 149a is slanted, not only does the encoder 149 have an increasing thickness in the axial direction, but it also becomes close to the sensor 1000. Thus, it is possible to have a significantly smaller inclined angle (θ ) than in the case of inclining the slinger 147.

[46] In this embodiment, the elastic part 143 is disposed on the seal support 141 and the seal lips extend from the elastic part 143 to contact the slinger 147. It should be noted, however, that the present invention is not limited to this configuration. Alternatively, the elastic part 143 may be disposed on the slinger 147 and the seal lips may extend from the elastic part 143 to contact the seal support 141.

[47] As shown in Figs. 6 to 9, the slinger 147 may have a third cylindrical portion 147d spaced away from the second cylindrical portion 147a and extending in the axial direction such that a seal lip 145d contacts the third cylindrical portion 147d to improve sealing performance of the seal 140.

[48] Although the present invention has been described in connection with the preferred embodiments and the drawings, it should be noted that the present invention is not limited to these embodiments and drawings. It will be apparent to those skilled in the art that modifications and variations can be made without departing from the spirit and scope of the present invention as defined by the appended claims.

Claims

[1] An encoder-integrated seal mounted on a bearing comprising a rotary ring, a stationary ring and a plurality of rolling elements between the rotary ring and the stationary ring to be located in an opening defined between the rotary ring and the stationary ring and facing the rolling elements, comprising: a seal support having a first cylindrical portion mounted on the stationary ring; a slinger having a first radial portion spaced away from the seal support outwardly and formed in a radial direction, a second radial portion extending from the first radial portion and slanted into the opening, and a second cylindrical portion extending directly from an end of the first or second radial portion in an axial direction and mounted on the rotary ring; an elastic part attached to the seal support or the slinger; at least one seal lip extending from the elastic part and contacting one side of the slinger or the seal support; and an encoder attached to at least one portion of each of the first and second radial portions.

[2] The seal according to claim 1, wherein the second radial portion has an inclined angle in the range of 15~25 degrees with respect to the first radial portion.

[3] The seal according to claim 2, wherein a height of the first radial portion in the radial direction is within 55% to 65% of a height of the slinger in the radial direction, and wherein a height of the second radial portion in the radial direction is within 35% to 45% of the height of the slinger in the radial direction.

[4] The seal according to claim 1, wherein the encoder attached to the at least one portion of each of the first and second radial portions has an outer surface slanted in the radial direction to have a gradually increasing thickness in an axial direction toward a center of a rotational axis, and wherein the outer surface of the encoder has an inclined angle in the range of 1-5 degrees in the radial direction.

[5] An encoder-integrated seal mounted on a bearing comprising a rotary ring, a stationary ring, and a plurality of rolling elements between the rotary ring and the stationary ring to be located in an opening defined between the rotary ring and the stationary ring and facing the rolling elements, comprising: a seal support having a first cylindrical portion mounted on the stationary ring; a slinger having a second cylindrical portion mounted on the rotary ring and a radial portion extending from the second cylindrical portion in a radial direction; an elastic part attached to the seal support or the slinger; at least one seal lip extending from the elastic part and contacting one side of the slinger or the seal support; and an encoder attached to an outer side of the radial portion and having an outer surface slanted to have a gradually increasing thickness toward a center of a rotational axis in the radial direction.

[6] The seal according to claim 5, wherein the outer surface of the encoder has an inclined angle in the range of 1-5 degrees in the radial direction.