JP2020003055A - Bearing cap with sensor unit and hub unit bearing - Google Patents

Abstract

To obtain a bearing cap with a sensor unit, which can secure sealing performance between a holder insertion hole and a holder shaft part, and also can make attachment workability of a sensor holder satisfactory, and can improve rotation speed detection accuracy satisfactory by thinning a thickness of a bottom part of the holder insertion hole.SOLUTION: An O-ring 15 is arranged between an inner peripheral face of an intermediate part in an axial direction of a holder insertion hole 36 and an outer peripheral face of an intermediate part in an axial direction of a holder shaft part 48 in a state of being compressed in a radial direction. An annular recess 53 whose inside diameter dis larger than an outside diameter of the O-ring 15 which is externally fit to the holder shaft part 48 before the insertion of the O-ring into the holder insertion hole 36 is provided in a range reaching a position adjacent to the inside of an arrangement position P of the O-ring 15 in the axial direction from an inside opening in the axial direction out of the inner peripheral face of the holder insertion hole 36 over an entire periphery.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a bearing cap with a sensor unit in which a sensor unit is attached to a bearing cap for closing an opening of an outer ring constituting a hub unit bearing, and a hub unit bearing provided with the bearing cap with the sensor unit.

  Conventionally, a hub unit bearing for rotatably supporting wheels of an automobile or the like with respect to a suspension device is combined with a rotation speed detection device for detecting a wheel rotation speed required for control of ABS or the like. Has been done.

  For example, Japanese Patent Application Laid-Open No. 2013-53638 discloses that an annular encoder constituting a rotation speed detecting device is supported on an axially inner portion of a hub constituting a hub unit bearing, and an outer ring constituting a hub unit bearing is provided. A structure is described in which a sensor unit constituting a rotation speed detecting device is attached to a bearing cap that closes an axially inner opening. In the structure described in Japanese Patent Application Laid-Open No. 2013-53638, a holder insertion hole penetrating in the axial direction is provided in a portion of the bearing cap that is axially opposed to a part of the circumferential direction of the encoder. The holder shaft of the sensor holder constituting the sensor unit, which holds the sensor at the tip, is inserted into the holder insertion hole. As a result, the detection unit of the sensor is made to closely approach the detection surface of the encoder. An O-ring made of an elastic material is sandwiched between the outer peripheral surface of the holder shaft and the inner peripheral surface of the holder insertion hole.

  According to the above structure, when the encoder rotates together with the wheel, the S pole and the N pole disposed on the detection surface of the encoder alternately pass near the detection unit of the sensor. For this reason, the density of the magnetic flux flowing through the detection unit of the sensor changes, and the output signal of the sensor changes. Since the frequency at which the output signal of the sensor changes is proportional to the number of revolutions of the wheel, sending the output signal of the sensor to the controller makes it possible to appropriately control the ABS and TCS.

  However, when the hub unit bearing is used in a severe muddy water environment and the sealing performance by the O-ring is insufficient, the structure described in Japanese Patent Application Laid-Open No. 2013-53638 discloses a bearing cap through a holder insertion hole which is a through hole. Muddy water can enter the space inside the building.

  In view of such circumstances, for example, JP-A-2006-136064 discloses a structure in which a sensor is opposed to an encoder via the bottom of the holder insertion hole by making the holder insertion hole a bottomed hole. Have been. According to such a structure, it is possible to effectively prevent foreign matter such as muddy water from entering the space inside the bearing cap through the holder insertion hole.

  However, in the structure described in JP-A-2006-136064, when moisture that has entered between the holder insertion hole and the holder shaft freezes, the bottom of the holder insertion hole may be damaged. For this reason, it is necessary to secure the strength of the bottom of the holder insertion hole, and it becomes difficult to reduce the thickness of the bottom of the holder insertion hole. As a result, the distance (air gap) between the detection unit of the sensor and the detection surface of the encoder increases, and the amount of magnetic flux that enters and exits the detection surface of the encoder and passes through the detection unit of the sensor decreases. Accuracy of rotation speed detection may be reduced.

  Further, the structure described in JP-A-2006-136064 discloses a structure in which a holder insertion hole is provided in a portion located below the holder insertion hole in a use state in order to prevent moisture from staying inside the holder insertion hole. There is a drain ditch reaching the bottom of the. However, on the contrary, there is a possibility that the water may enter the holder insertion hole through the drain groove provided for discharging the water.

JP 2013-53638 A JP-A-2006-136064

  In order to solve problems that can occur in the structures described in JP-A-2013-53638 and JP-A-2006-136064, for example, it is conceivable to adopt a structure as shown in FIG. The illustrated structure is an undisclosed structure that the present inventors considered before completing the present invention. In the illustrated structure, the holder insertion hole 2 provided in the bearing cap 1 is a bottomed hole whose inner diameter does not change in the axial direction except for the back end. An O-ring 4 made of an elastic material is sandwiched between the inner peripheral surface of the intermediate portion in the axial direction of the holder insertion hole 2 and the outer peripheral surface of the intermediate portion in the axial direction of the holder shaft portion 3.

  According to the above-described structure, similarly to the structure described in JP-A-2006-136064, since the holder insertion hole 2 is a bottomed hole, muddy water or the like enters the space inside the bearing cap 1 through the holder insertion hole 2. It is possible to effectively prevent foreign matter from entering. Further, since the O-ring 4 is sandwiched between the inner peripheral surface of the holder insertion hole 2 and the outer peripheral surface of the holder shaft portion 3, the O-ring 4 is located deeper (axially outward) than the portion where the O-ring 4 is sandwiched. It can prevent moisture from entering. Therefore, it is possible to prevent the bottom portion 5 of the holder insertion hole 2 from being damaged due to the freezing of the water, so that the thickness of the bottom portion 5 can be reduced. As a result, the distance between the detection unit of the sensor 6 held at the tip of the holder shaft 3 and the detection surface of the encoder (not shown) can be shortened, and the detection accuracy of the sensor 6 can be improved.

  However, in the structure shown in FIG. 9, when the holder shaft 3 is inserted into the holder insertion hole 2, the outer peripheral surface of the O-ring 4 externally fitted to the holder shaft 3 is, as shown by a two-dot chain line, the holder. The air existing inside the holder insertion hole 2 cannot escape to the outside from the stage where it comes into contact with the opening edge of the insertion hole 2. For this reason, in order to insert the holder shaft portion 3 to the desired position shown by the solid line, it is necessary to greatly compress the air inside the holder insertion hole 2. Therefore, there is a possibility that the holder shaft portion 3 is pushed back and the workability of mounting the sensor holder 7 is deteriorated, and the bottom portion 5 of the holder insertion hole 2 is broken due to an increase in the pressure in the holder insertion hole 2. is there. In order to allow air existing inside the holder insertion hole 2 to escape to the outside, it is conceivable to provide the bearing cap 1 with an air hole communicating with the inside of the holder insertion hole 2. However, if such an air hole is provided so as to open on the axial side surface of the bearing cap 1, the air hole may be a path through which moisture enters. Further, in order to make it difficult for the water to enter the passage of water, it is conceivable to provide the air hole so as to open in the radial direction. However, such an air hole is formed by forming the bearing cap 1 by axial draw molding. In case it is difficult.

  In view of the circumstances described above, the present invention not only ensures the sealing performance between the holder insertion hole and the holder shaft portion, but also has a good workability in attaching the sensor holder to the bearing cap, and also has the holder insertion hole. The invention has been made to realize a structure of a bearing cap with a sensor unit, which can improve the rotational speed detection accuracy by reducing the thickness of the bottom of the bearing cap.

Among the bearing cap with a sensor unit and the hub unit bearing of the present invention, the bearing cap with a sensor unit includes a bearing cap, a sensor unit, and an elastic ring.
The bearing cap has a bottomed cylindrical shape, and is mounted on an axially inner portion of an outer ring that rotatably supports a hub having an encoder, and closes an axially inner opening of the outer ring. Further, the bearing cap is a fitting cylindrical portion fitted and fixed to the outer ring, and closes an inner diameter side of the fitting cylindrical portion, and is provided only on the axially inner side in a portion axially opposed to a part of the encoder. A synthetic resin bottom plate provided with an opened bottomed holder insertion hole.
The sensor unit has a holder shaft inserted into the holder insertion hole, and has a sensor holder attached to the bearing cap, and a sensor held at a tip of the holder shaft.
The elastic ring is arranged in a radially compressed state between an inner peripheral surface of an axially intermediate portion of the holder insertion hole and an outer peripheral surface of an axially intermediate portion of the holder shaft portion.
Further, in the present invention, the holder insertion hole is formed in at least a part of the inner peripheral surface in the circumferential direction, and in a range extending from the axially inner opening to a position adjacent to the elastic ring in the axially inward position. An inner radius is larger than an outer radius of the elastic ring fitted to the holder shaft before being inserted into the holder insertion hole.

  When implementing the bearing cap with a sensor unit of the present invention, for example, the relief portion may be an annular concave portion provided on the entire inner circumferential surface of the holder insertion hole, or the holder It may be a concave groove provided in a part of the inner peripheral surface of the insertion hole in the circumferential direction.

  In the case where the relief portion is the annular concave portion, the bottom surface of the annular concave portion may be a tapered surface inclined in a direction in which the inner diameter increases toward the inner side in the axial direction, or the inner diameter extends in the axial direction. May be a constant cylindrical surface.

The hub unit bearing of the present invention has an outer ring raceway on the inner peripheral surface and does not rotate even during use, a hub that has an inner raceway on the outer peripheral surface and rotates during use, the outer raceway and the inner raceway. A plurality of rolling elements provided therebetween, an encoder supported coaxially with the hub at an axially inner portion of the hub, a bearing cap mounted at an axially inner portion of the outer ring, and a bearing cap. And an attached sensor unit.
In the hub unit bearing of the present invention, the bearing cap with the sensor unit, in which the sensor unit is attached to the bearing cap, is the bearing cap with the sensor unit of the present invention.

  ADVANTAGE OF THE INVENTION According to this invention, not only the sealing performance between a holder insertion hole and a holder shaft part can be ensured, but the mounting workability of the sensor holder with respect to a bearing cap can be made favorable, and the bottom of the holder insertion hole can be improved. By reducing the thickness, the rotation speed detection accuracy can be improved.

FIG. 1 is a cross-sectional view showing a hub unit bearing with a rotation speed detecting device according to a first example of an embodiment. FIG. 2 is an enlarged view of a portion corresponding to the upper right portion of FIG. FIG. 3 is a sectional view showing a bearing cap taken out from a hub unit bearing with a rotation speed detecting device according to the first example of the embodiment. FIG. 4 is a view of the bearing cap viewed from the left side of FIG. FIG. 5 is a view of the bearing cap viewed from the right side of FIG. 6A and 6B are diagrams illustrating a process of inserting a holder shaft portion having an O-ring externally fitted into a holder insertion hole, and FIG. 6A illustrates an initial stage in which the O-ring exists on the inner diameter side of the tapered surface; (B) shows a middle stage in which the O-ring exists on the inner diameter side of the guide taper surface, and (C) shows a final stage in which the O-ring exists on the inner diameter side of the supporting cylindrical surface. FIG. 7 is a diagram illustrating a second example of the embodiment and corresponding to FIG. 2. FIG. 8 is a diagram illustrating a third example of the embodiment and corresponding to FIG. 2. FIG. 9 is a view corresponding to FIG. 2 and showing a non-disclosed conventional structure.

[First Example of Embodiment]
A first example of the embodiment will be described with reference to FIGS.
The hub unit bearing 8 of the present embodiment supports the wheel rotatably with respect to the suspension device and detects the rotation speed of the wheel. The outer ring 9 does not rotate in the use state and rotates together with the wheel in the use state. The vehicle includes a hub 10, a plurality of rolling elements 11, an outer sealing member 12, a bearing cap 13, a rotational speed detecting device 14, and an O-ring 15 as an elastic ring.

  In addition, regarding the hub unit bearing 8, the outer side in the axial direction is the left side in FIG. 1 to FIG. 3 and FIG. 6, which is the outer side in the width direction of the vehicle when assembled to the vehicle. FIG. 7 is a right side of FIGS. 1 to 3 and FIG. 6 which is a center side in a width direction of the vehicle.

  The outer race 9 has double rows of outer raceways 16a and 16b on the inner peripheral surface, and has the stationary flange 17 on the outer peripheral surface. The stationary flange 17 is provided at an axially intermediate portion of the outer ring 9 so as to protrude radially outward. The outer ring 9 does not rotate in use in order to fix the stationary flange 17 to a suspension device such as a knuckle. The outer ring 9 is made of medium carbon steel such as S53C, for example, and at least the surfaces of the outer ring raceways 16a and 16b are subjected to hardening treatment such as induction hardening.

  The hub 10 is disposed coaxially with the outer ring 9 on the inner diameter side of the outer ring 9, and is configured by combining a hub wheel 18 and an inner ring 19. The hub wheel 18 is a shaft member that externally holds the inner ring 19, and has a shaft portion 20 and a rotating flange 21. The shaft portion 20 is provided in a range from the inside in the axial direction of the hub wheel 18 to the middle portion in the axial direction. The shaft portion 20 has a small-diameter stepped portion 22 for externally fitting the inner ring 19 on the inner side in the axial direction, and has an inner ring raceway 23a in the axially outer row on the outer peripheral surface of the axially intermediate portion. I have. A caulking portion 24 that is bent radially outward is formed on the inner side in the axial direction of the shaft portion 20, and the caulking portion 24 suppresses the axial inner end surface of the inner ring 19. The rotating flange 21 protrudes radially outward from the axially outer portion of the hub wheel 18 adjacent to the shaft portion 20 in the axial direction, and has a substantially circular shape. The inner ring 19 is externally fitted to the small-diameter step portion 22 of the hub wheel 18, and has an inner ring raceway 23b in an axially inner row on the outer peripheral surface. The hub 10 has a rotating flange 21 to which wheels constituting wheels and a rotating body for braking are fixed, and rotates during use. The hub wheel 18 is made of medium carbon steel such as S53C, for example, and a hardening process such as induction hardening is applied to at least the outer peripheral surface of the shaft portion 20 including the surface of the inner raceway 23a. On the other hand, the inner ring 19 is made of high-carbon chromium bearing steel such as SUJ2, for example, and is subjected to hardening treatment by soaking.

  The rolling element 11 is rotatably held by a retainer (not shown), and is disposed between the double-row outer raceways 16a and 16b and the double-row inner raceways 23a and 23b. Thus, the hub 10 is rotatably supported on the inner diameter side of the outer ring 9. Although a ball is used as the rolling element 11 in the illustrated example, a tapered roller may be used in the case of a heavy hub unit bearing for an automobile.

  Grease (not shown) is sealed in a space 25 that is present between the inner peripheral surface of the outer race 9 and the outer peripheral surface of the hub 10 and in which the plurality of rolling elements 11 are installed. Then, in order to prevent the grease sealed in the space 25 from leaking to the outside, and to prevent foreign matter such as muddy water from entering the space 25, the outer opening in the axial direction of the space 25 is formed by the outer sealing member 12. I'm blocking. On the other hand, a bottomed cylindrical bearing cap 13 is attached to the inner side of the outer ring 9 in the axial direction to close the axially inner opening of the outer ring 9.

  The bearing cap 13 includes a substantially disc-shaped cap main body 26 made of synthetic resin, a metal ring 27 and a nut 28 molded and fixed to the cap main body 26, and has a substantially cylindrical fitting cylindrical portion 29. And a substantially disk-shaped bottom plate portion 30 that closes the inner diameter side of the fitting tube portion 29.

  The cap body 26 is made by injection molding (axial draw molding) of a synthetic resin. As the synthetic resin forming the cap body 26, for example, a fiber reinforced polyamide resin material obtained by appropriately adding glass fiber to polyamide 66 resin can be used. If necessary, an amorphous aromatic polyamide resin (modified polyamide 6T / 6I) and a low water-absorbing aliphatic polyamide resin (polyamide 11 resin, polyamide 12 resin, polyamide 610 resin, polyamide 612 resin) may be used as the polyamide resin. The water resistance may be further improved by adding as appropriate.

  A metal ring 27 made of a stainless steel plate, a rolled steel plate, or the like is molded and fixed to a radially outer portion of the cap body 26. The metal ring 27 has a substantially L-shaped cross-sectional shape, and includes a cylindrical portion 31 and an outward flange portion 32 bent radially outward from an axially inner portion of the cylindrical portion 31. The cylindrical portion 31 protrudes axially outward from a radially outer portion of the cap body 26, and forms a fitting cylindrical portion 29 of the bearing cap 13. The outward flange portion 32 is embedded inside a radially outer portion of the cap body 26 at a position axially overlapping a surface against which a pressing jig is pressed when the bearing cap 13 is pressed into the outer ring 9, The pressure input by the pressing jig is transmitted to the fitting cylinder 29. A locking groove 33 is formed over the entire circumference on the axially outer surface of the radially outer portion of the cap body 26. An O-ring 34 is locked in the locking groove 33.

  A portion of the cap body 26 that is located radially inward from the portion where the metal ring 27 is molded blocks the inner diameter side of the metal ring 27 and forms the bottom plate portion 30 of the bearing cap 13. The bottom plate portion 30 has a thick portion 35 having a greater thickness (thickness) in the axial direction than other portions. The thick portion 35 is provided at a portion located vertically above the bottom plate portion 30 and at the center in the front-rear direction with the hub unit bearing 8 assembled to the vehicle.

  In the upper part of the thick portion 35, a holder insertion hole 36, which is a bottomed hole opened only inside in the axial direction, is provided at a portion axially opposed to a part of a detection surface of the encoder 42 described later. . The inner part of the holder insertion hole 36 is closed by a bottom part 37. A bag-like nut 28 is molded and fixed radially inside the thick portion 35. The nut 28 has a female screw portion 38 formed on the inner peripheral surface, and an engagement groove 39 formed on the outer peripheral surface. A part of the synthetic resin constituting the thick portion 35 enters the inside of the engagement groove 39. At a radially intermediate portion of the thick portion 35, a portion between the holder insertion hole 36 and the nut 28 is provided with a thinned portion 40 that is opened only outward in the axial direction.

  A plurality of ribs 41a and 41b are provided on the axially outer surface of the bottom plate portion 30. The rib 41a has a flat plate shape, and is provided so as to extend in the radial direction from the center of the bottom plate portion 30. The rib 41b has a cylindrical shape and is arranged coaxially with the bottom plate 30. Such ribs 41a and 41b are provided to ensure the strength of the cap body 26 and to improve the flow of the molten resin when the cap body 26 is manufactured by injection molding.

  In the bearing cap 13 as described above, the fitting cylindrical portion 29 formed by the cylindrical portion 31 of the metal ring 27 is tightly fitted and fixed to the axially inner portion of the outer ring 9 in the axial direction of the outer ring 9. Mounted on the inside. In addition, the axial outer surface of the radially outer portion of the cap body 26 is abutted against the axial inner end surface of the outer ring 9, thereby positioning the bearing cap 13 with respect to the outer ring 9 in the axial direction. Further, the O-ring 34 is elastically sandwiched between the axial inner end surface of the outer ring 9 and the bottom surface of the locking groove 33 of the cap body 26, so that the axial outer surface of the radially outer portion of the cap body 26 is formed. Through the contact portion between the outer ring 9 and the inner end surface in the axial direction, foreign matter such as moisture is prevented from entering the inside of the bearing cap 13.

The rotation speed detection device 14 includes an encoder 42 and a sensor unit 43.
The encoder 42 has an annular shape, and is supported and fixed to the outer peripheral surface of the inner ring 19 of the hub 10 in the axial direction while being coaxial with the hub 10. The encoder 42 has a support ring 44 and an encoder body 45. The support ring 44 is made of a magnetic metal plate, and is formed by press working. The support ring 44 has a substantially L-shaped cross section, and is externally fitted and fixed to the axially inner portion of the inner ring 19 by interference fit. The encoder main body 45 is made of a permanent magnet such as a rubber magnet or a plastic magnet mixed with a magnetic substance such as a ferrite powder, and is fixed to an axial inner surface of the support ring 44. S poles and N poles are alternately arranged at equal pitches in the circumferential direction on the detection surface, which is the inner surface in the axial direction of the encoder body 45.

  The sensor unit 43 is attached to the bearing cap 13 and includes a sensor holder 46 made of a synthetic resin and a sensor 47. The sensor holder 46 has a columnar (rod-shaped) holder shaft 48 and a mounting flange 49 provided on the base end side of the holder shaft 48. The outer diameter of the holder shaft portion 48 does not change in the axial direction except for a portion where a locking groove 51 described later is formed. The sensor 47 is composed of an IC incorporating a magnetic sensing element such as a Hall IC, a Hall element, an MR element, a GMR element, and a waveform shaping circuit, and is held (molded) at the tip of a holder shaft 48.

  The sensor unit 43 is configured such that a male screw portion of a bolt (not shown) inserted through a through hole 50 provided in the mounting flange portion 49 is screwed into the female screw portion 38 of the nut 28 molded on the bottom plate portion 30 to thereby provide a bearing cap. 13 is attached. In such an attached state, the holder shaft portion 48 is inserted inside the holder insertion hole 36. The sensor 47 held at the distal end of the holder shaft 48 is axially close to the detection surface of the encoder 42 (encoder body 45) via the bottom 37 of the holder insertion hole 36.

  In order to ensure the sealing performance between the holder insertion hole 36 and the holder shaft 48, the gap between the inner peripheral surface of the holder insertion hole 36 in the axial middle and the outer peripheral surface of the holder shaft 48 in the axial middle is provided. The O-ring 15 is arranged in a state of being compressed in the radial direction, that is, an inner peripheral surface of the holder insertion hole 36 and an outer peripheral surface of the holder shaft portion 48 are provided with interference. In the present example, the O-ring 15 is attached to the intermediate position of the holder shaft 48 in the axial direction so that the operation of inserting the holder shaft 48 and the operation of arranging the O-ring 15 at the intended arrangement position P can be performed simultaneously. It is externally fitted (locked) to an annular locking groove 51 having a substantially rectangular cross-sectional shape formed on the outer peripheral surface of the portion. The O-ring 15 is made of an elastic material such as rubber, has a substantially circular cross-section in a free state, and has a wire diameter larger than the groove depth of the locking groove 51. Note that the arrangement position P of the O-ring 15 is an axial position where the center of the O-ring 15 is located in a state where the work of inserting the holder shaft portion 48 is completed.

In the present example, when the holder shaft portion 48 with the O-ring 15 fitted outside is inserted into the holder insertion hole 36, the air inside the holder insertion hole 36 is released to the outside, and the air inside the holder insertion hole 36 is excessively discharged. The shape of the inner peripheral surface of the holder insertion hole 36 is devised so as not to be compressed.
Specifically, in the inner peripheral surface of the holder insertion hole 36, a range from the axially outer portion to the intermediate portion including the arrangement position P of the O-ring 15 is a supporting cylindrical surface 52 whose inner diameter does not change in the axial direction. Then, the inner diameter d ₅₂ of the support cylindrical surface 52, slightly larger than the outer diameter D ₄₈ of the holder shaft 48, and, in prior to insertion into the holder insertion hole 36 of the O-ring 15 which is fitted to the holder shaft 48 It is smaller than the outer diameter D ₁₅ (hereinafter, referred to as “ring outer diameter D ₁₅ before reduced diameter”; see FIG. 6A) (D ₄₈ <d ₅₂ <D ₁₅ ). This allows the O-ring 15 to be compressed in a state where the O-ring 15 is disposed on the inner diameter side of the support cylindrical surface 52, and prevents the front end of the holder shaft 48 from rattling inside the support cylindrical surface 52. It is preventing.

Further, among the inner circumferential surface of the holder insertion hole 36, the range extending position adjacent axially inner position P of the O-ring 15 from the axially inner opening, the inner diameter d ₅₃ is reduced diameter front ring outer diameter D ₁₅ (inner radius _{d 53/2} is the outer radius _D 15/2 of the O-ring 15) is greater than is provided an annular recess 53 is a relief portion over the entire circumference. In addition, the bottom surface (inner peripheral surface) of the annular concave portion 53 is a tapered surface 54 that is inclined in such a direction that the inner diameter increases toward the inner side in the axial direction (the opening side of the holder insertion hole 36). The axial length (depth from the opening) of the annular concave portion 53 (tapered surface 54) is determined by the relationship with the arrangement position P of the O-ring 15, but, for example, the axial depth of the holder insertion hole 36 is determined. It can be about 20% to 40%. In addition, since the thickness (outer wall) around the holder insertion hole 36 is small, the inclination angle of the tapered surface 54 cannot be made too steep. 48, the diameter of the O-ring 15 locked in the locking groove 51 is larger than the outer diameter of the O-ring 15, the holder shaft portion 48 locking the O-ring 15 can be smoothly inserted into the holder insertion hole 36, and From the viewpoint that a sufficient squeeze allowance is given to the O-ring 15 after the insertion operation of the holder shaft portion 48 is completed, for example, the angle can be about 0.5 ° to 5 °.

Further, a guide tapered surface 55 is provided at a portion between the support cylindrical surface 52 and the tapered surface 54 at an axially intermediate portion of the inner peripheral surface of the holder insertion hole 36. The guide taper surface 55 is a portion where the outer peripheral surface of the O-ring 15 externally fitted to the holder shaft portion 48 comes into contact when the holder shaft portion 48 is inserted inside the holder insertion hole 36, as described later. It has the same inclination angle as the tapered surface 54 and is smoothly continuous with the tapered surface 54. The inner diameter d ₅₅ of the guide tapered surface 55 is smaller toward the axially outward. That is, the guide taper surface 55 has an axially outer portion connected to the support cylindrical surface 52, and the inner diameter d ₅₅ of the axially outer end portion is the same as the inner diameter d ₅₂ of the support cylindrical surface 52. On the other hand, the guide taper surface 55 is connected to the taper surface 54 at the inner side in the axial direction, and the inner diameter d ₅₅ at the inner end in the axial direction is the same as the outer diameter D _{15 of the} pre-reducing ring. Note that the inclination angle of the guide taper surface 55 can be different from the inclination angle of the taper surface 54.

  According to the hub unit bearing 8 of the present embodiment as described above, the wheels can be rotatably supported by the suspension device, and the rotation speed of the wheels can be detected. Therefore, ABS and TCS can be appropriately controlled.

  In particular, in this example, not only the sealing performance between the holder insertion hole 36 and the holder shaft portion 48 can be ensured, but also the workability of attaching the sensor holder 46 to the bearing cap 13 can be improved, and the holder insertion hole can be improved. By reducing the thickness of the bottom portion 37 of 36, the accuracy of rotation speed detection by the sensor 47 can be improved.

  That is, since the O-ring 15 is arranged in a manner having a margin between the inner peripheral surface of the axially intermediate portion of the holder insertion hole 36 and the outer peripheral surface of the axially intermediate portion of the holder shaft portion 48. In addition, it is possible to prevent moisture from penetrating deeper (axially outside) than the portion where the O-ring 15 is sandwiched. Therefore, it is possible to prevent the bottom portion 37 of the holder insertion hole 36 from being damaged due to the freezing of water.

Further, the reason why the mounting workability of the sensor holder 46 can be improved and the thickness of the bottom portion 37 of the holder insertion hole 36 can be reduced to improve the rotation speed detection accuracy by the sensor 47 is described. The mounting operation of 46 will be described in detail with reference to FIG.
As shown in FIG. 6A, when the holder shaft portion 48 with the O-ring 15 fitted thereinto is inserted into the inside of the holder insertion hole 36, the O-ring 15 is tapered on the bottom surface of the annular recess 53. In the stage located on the inner diameter side of the O-ring 15, a gap 56 can be provided between the outer peripheral surface of the O-ring 15 and the tapered surface 54. For this reason, the holder shaft portion 48 is further inserted, and the air inside the holder insertion hole 36 is maintained until the outer peripheral surface of the O-ring 15 contacts the guide tapered surface 55 as shown in FIG. Through the gap 56 to the outside. In addition, since the tapered surface 54 is provided up to a position adjacent to the inside of the O-ring 15 in the axial direction of the disposition position P, as shown in FIG. The amount of insertion of the holder shaft 48 between the time when the holder shaft 55 is brought into contact with the position 55 and the time when the holder shaft 48 is moved to the arrangement position P is sufficiently short. Therefore, it is possible to prevent the air inside the holder insertion hole 36 from being excessively compressed. Thereby, the holder shaft portion 48 can be prevented from being pushed back, and the mounting workability of the sensor holder 46 can be improved. Further, since it is not necessary to increase the strength (thickness) of the bottom portion 37 of the holder insertion hole 36 in order to withstand the compressed air pressure, the thickness of the bottom portion 37 is reduced, and the rotation speed detection accuracy by the sensor 47 is improved. Can be planned.

  In addition, since the tapered surface 54 has a function of guiding the tip of the holder shaft 48, the holder shaft 48 can be smoothly inserted into the opening of the holder insertion hole 36. Further, the diameter of the O-ring 15 passing through the tapered surface 54 can be gradually reduced by the guide tapered surface 55 having the same inclination angle as the tapered surface 54. Therefore, the O-ring 15 can be smoothly pushed into the inner diameter side of the support cylindrical surface 52. Therefore, also from this aspect, the mounting workability of the sensor holder 46 can be improved.

[Second Example of Embodiment]
A second example of the embodiment will be described with reference to FIG.
In this example, the inner diameter d _{53a of} the inner diameter d _53a of the inner peripheral surface of the holder insertion hole 36a extends from the inner opening in the axial direction to a position adjacent to the inner side in the axial direction of the arrangement position P of the O-ring 15. D is greater than ₁₅ (the outer radius _D 15/2 of internal radius _{d 53a} / 2 is O-ring 15) is provided an annular recess 53a over the entire circumference. Further, the bottom surface (inner peripheral surface) of the annular concave portion 53a is a cylindrical surface 57 having a constant inner diameter in the axial direction. Further, the support cylindrical surface 52 and the cylindrical surface 57 are continuous via a step surface 58.

Also in the case of the present embodiment as described above, when the holder shaft portion 48 with the O-ring 15 fitted outside is inserted into the holder insertion hole 36a, the outer peripheral surface of the O-ring 15 is A gap 56 can be provided between the annular concave portion 53a and the cylindrical surface 57 that is the bottom surface of the annular concave portion 53a. Therefore, the air inside the holder insertion hole 36a can escape to the outside through the gap 56. Further, the inner diameter _{d 53a} of the cylindrical surface 57 if slightly larger than the reduced diameter front ring outer diameter _{D 15,} the cylindrical surface 57 centering the O-ring 15 (the holder insertion hole 36a and the holder shaft 48 It can also be used as a guide surface for performing (centering).
When the present embodiment is carried out, the supporting cylindrical surface 52 and the cylindrical surface 57 are formed by a guide taper surface whose inner diameter becomes smaller toward the inside in the axial direction as in the structure of the first example of the embodiment. It can be continuous or can be continuous by a convex curved surface having an arc-shaped cross section.
Other configurations and operational effects are the same as those of the first example of the embodiment.

[Third Example of Embodiment]
A third example of the embodiment will be described with reference to FIG.
In this example, a part of the inner circumferential surface of the holder insertion hole 36b in the circumferential direction is radially outwardly recessed in a range from the axially inner opening to a position adjacent to the O-ring 15 disposed position P in the axial direction. A concave groove 59 extending in the axial direction in the state is provided. Inner radius _{d 53b} of the groove 59 is larger than the outer radius _{D 15/2} in prior to insertion into the holder insertion hole 36b of the elastic ring 15 which is fitted to the holder shaft 48. The bottom surface of the concave groove 59 is a partial cylindrical surface 57a having a constant inner diameter in the axial direction. Further, the support cylindrical surface 52 and the partial cylindrical surface 57a are connected by a step surface 58a. In addition, a ridge (continuous portion) between the support cylindrical surface 52 and the step surface 58a, and a ridge between a circumferential side surface of the concave groove 59 and a portion deviated in the circumferential direction from the concave groove 59. Has a convex curved surface 60 having an arc-shaped cross section to prevent the O-ring 15 from being damaged by the ridge. Instead of the convex curved surface 60, an inclined surface whose inner diameter gradually changes can be provided.

Also in the case of the present embodiment as described above, when the holder shaft portion 48 with the O-ring 15 externally fitted therein is inserted into the holder insertion hole 36b, a part of the outer peripheral surface of the O-ring 15 (the lower part of FIG. A gap 56 can be provided between the side portion) and the partial cylindrical surface 57a which is the bottom surface of the concave groove 59. Therefore, the air inside the holder insertion hole 36b can escape to the outside through the gap 56.
Other configurations and operational effects are the same as those of the first example of the embodiment.

  In practicing the present invention, the shape of the bottom surface of the annular concave portion and the concave groove formed on the inner peripheral surface of the holder insertion hole is not limited to a tapered surface or a cylindrical surface (partial cylindrical surface), and other shapes may be employed. Is also good. Further, when forming a concave groove on the inner peripheral surface of the holder insertion hole, the number of concave grooves is not limited to one, and a plurality of concave grooves can be formed. Further, in the embodiment, the bearing cap has been described by taking as an example a structure in which a cap body made of a synthetic resin and a member made of a material other than the synthetic resin such as a metal metal ring are combined. In practicing the invention, the bearing cap may be entirely made of synthetic resin. Further, the structures of the respective embodiments of the embodiments can be implemented in appropriate combinations.

DESCRIPTION OF SYMBOLS 1 Bearing cap 2 Holder insertion hole 3 Holder shaft part 4 O-ring 5 Bottom part 6 Sensor 7 Sensor holder 8 Hub unit bearing 9 Outer ring 10 Hub 11 Rolling element 12 Outer sealing member 13 Bearing cap 14 Rotational speed detector 15 O-ring 16a, 16b Outer ring raceway 17 Stationary flange 18 Hub wheel 19 Inner ring 20 Shaft part 21 Rotating flange 22 Small diameter stepped part 23a, 23b Inner ring raceway 24 Caulking part 25 Space 26 Cap body 27 Metal ring 28 Nut 29 Fitting cylinder part 30 Bottom plate part 31 Cylindrical part 32 Outward flange part 33 Lock groove 34 O-ring 35 Thick part 36, 36a, 36b Holder insertion hole 37 Bottom part 38 Female screw part 39 Engagement concave groove 40 Lightening part 41a, 41b Rib 42 Encoder 43 Sensor unit 44 Support ring 45 Encoder Main body 46 Sensor holder 7 Sensor 48 Holder Shaft 49 Mounting Flange 50 Through Hole 51 Locking Groove 52 Support Cylindrical Surface 53, 53a Annular Recess 54 Tapered Surface 55 Guide Tapered Surface 56 Gap 57 Cylindrical Surface 57a Partial Cylindrical Surface 58, 58a Step Surface 59 Concave Groove 60 convex surface

Claims (6)

A fitting cylindrical portion mounted on an axially inner portion of an outer ring rotatably supporting a hub having an encoder to close an axially inner opening of the outer ring, and fitted and fixed to the outer ring; A synthetic resin bottom plate portion that closes the inner diameter side of the combined tube portion and has a holder insertion hole with a bottomed hole opened only in the axial direction at a portion facing the part of the encoder in the axial direction; A bottomed cylindrical bearing cap,
A sensor unit having a holder shaft inserted into the holder insertion hole, having a sensor holder attached to the bearing cap, and a sensor held at a tip end of the holder shaft;
An elastic ring arranged in a radially compressed manner between an inner peripheral surface of an axial intermediate portion of the holder insertion hole and an outer peripheral surface of an axial intermediate portion of the holder shaft portion,
The holder insertion hole has at least a part of the inner peripheral surface in the circumferential direction, and has an inner radius in a range from the axial inner opening to a position adjacent to the inner side in the axial direction of the disposition position of the elastic ring. Having a relief portion that is larger than the outer radius of the elastic ring externally fitted to the holder shaft before being inserted into the holder insertion hole,
Bearing cap with sensor unit.   The bearing cap with a sensor unit according to claim 1, wherein the relief portion is an annular concave portion provided on the entire inner peripheral surface of the holder insertion hole.   The bearing cap with a sensor unit according to claim 2, wherein a bottom surface of the annular concave portion is a tapered surface inclined in a direction in which an inner diameter increases toward an inner side in the axial direction.   The bearing cap with a sensor unit according to claim 2, wherein the bottom surface of the annular concave portion is a cylindrical surface having a constant inner diameter in the axial direction.   The bearing cap with a sensor unit according to claim 1, wherein the relief portion is a concave groove provided on a part of an inner peripheral surface of the holder insertion hole in a circumferential direction. An outer ring having an outer raceway on an inner peripheral surface and not rotating even during use, a hub having an inner raceway on an outer peripheral surface and rotating during use, and a plurality of hubs provided between the outer raceway and the inner raceway. A rolling element, an encoder coaxially supported by the hub on the axially inner portion of the hub, a bearing cap mounted on the axially inner portion of the outer ring, and a sensor unit mounted on the bearing cap. A hub unit bearing provided with
A hub unit bearing, wherein a bearing cap with a sensor unit obtained by attaching the sensor unit to the bearing cap is the bearing cap with a sensor unit according to any one of claims 1 to 5.

Images