JP2008144861A - Bearing unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bearing unit in which the rotational speed of a wheel is accurately measured without being influenced by relative inclination between a stationary ring and a rotary ring. <P>SOLUTION: This bearing unit is provided with the stationary ring (outer ring) 2 normally maintained in non-rotating condition, the rotary ring (inner ring) 4 rotating together with the wheel, a plurality of rolling elements 6, 8 rotatably installed between the stationary ring and the rotary ring, and a rotation detecting mechanism for detecting the rotational speed of the wheel. The rotation detecting mechanism is provided with an encoder 20 coupled to the rotary ring and rotating together with the rotary ring, and a sensor 22 detecting information characteristics recorded in the encoder. With the sensor positioned opposingly to the encoder, the sensor is supported by a sensor supporting body 26. The sensor supporting body is coupled to the rotary ring through a bearing assembly (bearing 28) and also normally maintained in the non-rotating condition by detent structures (projecting part 32 and recessed part 34) constructed between the sensor supporting body and the stationary ring. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a bearing unit capable of rotatably supporting a wheel (for example, a disc wheel) of an automobile with respect to a vehicle body (for example, a suspension device (suspension device)) and detecting a rotation speed of the wheel.

  2. Description of the Related Art Conventionally, various bearing units (Patent Document 1) for rotatably supporting automobile wheels (for example, disc wheels) with respect to a vehicle body (for example, a suspension device (suspension)) are known. As an example, FIG. 3 shows a bearing unit for a driven wheel. The bearing unit is fixed to the vehicle body side and is always kept in a non-rotating state, and a stationary wheel 2. Between the stationary wheel 2 and the rotating wheel 4 so as to be rotatable in a double row (for example, two rows). And a plurality of rolling elements 6,8.

  In this case, the stationary wheel 2 has a hollow cylindrical shape and is disposed so as to cover the outer periphery of the rotating wheel 4, so that the inside of the bearing unit is sealed between the stationary wheel 2 and the rotating wheel 4. Are provided (lip seal 10a on the wheel side, cover (cap) 10b on the vehicle body side). The lip seal 10a is fixed to the stationary surface 2n-1 on the wheel side of the stationary wheel 2 and is slidably positioned with respect to the sliding surface 4n-1 of the rotating wheel 4. On the other hand, the cover (cap) 10b has a disk shape that can cover and seal the entire vehicle body side of the stationary wheel 2 and has a base end 10c formed on the vehicle body side of the stationary wheel 2. It is fixed to the side end 2n-2. In the drawings, balls are illustrated as the rolling elements 6 and 8, but rollers may be applied depending on the configuration and type of the bearing unit.

  The stationary ring (outer ring) 2 is integrally formed with a fixing flange 2a protruding outward from the outer peripheral side thereof, and a fixing bolt (not shown) is inserted into the fixing hole 2b of the fixing flange 2a. The stationary wheel 2 can be fixed to a suspension device (knuckle) (not shown). The rotating wheel (inner ring) 4 is provided with a substantially cylindrical hub (spindle) 12 that rotates together with, for example, a disc wheel (not shown) of an automobile, and the hub 12 has a disc wheel. A fixed hub flange 12a is projected.

  The hub flange 12a extends outward (outward in the radial direction of the hub 12) beyond the stationary ring (outer ring) 2, and is arranged at predetermined intervals along the circumferential direction in the vicinity of the extended edge. A plurality of hub bolts 14 are provided. In this case, by inserting a plurality of hub bolts 14 into bolt holes (not shown) formed in the disc wheel and tightening with hub nuts (not shown), the disc wheel can be positioned and fixed with respect to the hub flange 12a. it can. At this time, positioning in the radial direction of the wheel is performed by a pilot portion 12d protruding from the wheel side of the hub 12.

  The hub 12 (rotating wheel 4) is fitted (externally fitted) with an annular rotating wheel constituting body 16 (an inner ring constituting the rotating wheel 4 together with the hub 12) on the fitting surface 4n-2 on the vehicle body side. It has become so. In this case, for example, in a state where the rolling elements 6 and 8 are held by the cage 18 between the stationary wheel 2 and the rotating wheel 4, the rotating wheel component 16 is formed on the fitting surface 4n-2. After fitting (external fitting), the caulking region 12c at the end of the hub 12 on the vehicle body side is plastically deformed, and the caulking region 12c is caulked along the peripheral end 16s of the rotating wheel component 16 ( The rotating wheel constituting body 16 can be fixed to the rotating wheel 4 (hub 12).

  At this time, a predetermined preload is applied to the bearing unit, and in this state, the rolling elements 6 and 8 form a predetermined contact angle with each other so that the raceway surfaces of the stationary wheel 2 and the rotating wheel 4 (stationary). The raceway surface 2s and the rotary raceway surface 4s) are respectively brought into contact with and rotatable. In this case, an action line (not shown) connecting the two contact points is perpendicular to the raceway surfaces 2s and 4s and passes through the centers of the rolling elements 6 and 8, so that one point on the center line of the bearing unit (the action point). ) This constitutes a rear combination (DB) bearing.

  In such a configuration, all of the force acting on the wheel during traveling of the vehicle is transmitted from the disk wheel to the suspension device through the bearing unit. At that time, various loads (radial loads) are applied to the bearing unit. , Axial load, moment load, etc.). However, since the bearing unit is a back combination (DB) bearing as described above, high rigidity is maintained with respect to various loads.

  Further, the bearing unit described above is provided with a rotation detection mechanism for detecting the rotation speed of the wheel. As a rotation detection mechanism, a mechanism that detects rotation optically or magnetically is known. As an example, FIG. 3 shows a rotation detection mechanism that detects magnetic rotation. In this case, the rotation detection mechanism includes an annular encoder 20 that rotates together with the rotating wheel 4, and a sensor 22 that detects a magnetic characteristic (information characteristic) of the encoder 20. Here, the encoder 20 is concentrically attached to the rotating wheel 4 (the rotating wheel component 16) via the support member 24, while the sensor 22 is positioned facing the encoder 20, A cover (cap) 10 b fixed to the stationary wheel 2 is attached.

In this case, the encoder 20 is configured such that the magnetic characteristics are alternately changed along the circumferential direction (for example, the S pole and the N pole are alternately changed along the circumferential direction). The magnetic change per unit time of the encoder 20 that rotates with the sensor 4 is detected by the sensor 22. At this time, the detection signal output from the sensor 22 is sent to an ECU (Electronic on the vehicle body side) via a harness (not shown) or a radio wave (wireless), for example.
Control Unit: not shown), and the rotation speed of the wheel is measured by applying a predetermined calculation process to the detection signal.

  By the way, in order to measure the rotational speed of the wheel with high accuracy, it is necessary that the gap (gap) G between the encoder 20 and the sensor 22 is always kept constant. However, since the bearing unit having the axle structure always receives a moment load when the vehicle is traveling, the gap (gap) G may change depending on the magnitude of the moment load. A specific example will be described. When an external force is applied to the bearing unit from the wheel side when the vehicle is running, a relative inclination is generated between the stationary wheel (outer ring) 2 and the rotating wheel (inner ring) 4, thereby generating a moment. A load is generated. Since the moment load repeatedly fluctuates in accordance with the traveling state of the automobile, the relative inclination state between the stationary wheel (outer wheel) 2 and the rotating wheel (inner wheel) 4 also continues to fluctuate.

  Here, since the encoder 20 and the sensor 22 are fixed to the stationary wheel (outer ring) 2 and the rotating wheel (inner ring) 4, between the stationary wheel (outer ring) 2 and the rotating wheel (inner ring) 4. When a relative inclination occurs, a relative inclination also occurs between the encoder 20 and the sensor 22. If the relative inclination state between the stationary wheel (outer wheel) 2 and the rotating wheel (inner wheel) 4 continues to fluctuate according to the running state of the automobile, the gap between the encoder 20 and the sensor 22 is accordingly changed. The (gap) G also fluctuates repeatedly, which may make it difficult to keep the gap (gap) G constant.

In this case, the output value of the detection signal output from the sensor 22 becomes unstable depending on the degree of fluctuation of the gap (gap) G. Further, it is necessary to set a gap (gap) G so that the encoder 20 and the sensor 22 do not interfere (contact) with each other even if they are relatively inclined. Depending on the size of the gap (gap) G at that time, The magnetic change of the encoder 20 cannot be reliably detected by the sensor 22. If it becomes so, it will become impossible to perform a calculation process with high precision in said ECU, As a result, there exists a possibility that the rotational speed of a wheel cannot be measured with high precision.
JP-A-2005-214300

  The present invention has been made to solve such problems, and its purpose is to measure the rotational speed of the wheel with high accuracy without being affected by the relative inclination between the stationary wheel and the rotating wheel. It is an object of the present invention to provide a bearing unit that can be used.

  In order to achieve such an object, the present invention provides a stationary wheel that is fixed to the vehicle body side and is maintained in a non-rotating state at all times, and is provided facing the stationary wheel and connected to the wheel side to rotate together with the wheel. A bearing unit comprising a rotating wheel that rotates, a plurality of rolling elements rotatably incorporated between the stationary wheel and the rotating wheel, and a rotation detection mechanism for detecting the rotation speed of the wheel. The mechanism is provided with an encoder that is connected to the rotating wheel and rotates together with the rotating wheel, and a sensor that detects information characteristics recorded in the encoder, and the sensor is supported by the sensor while being positioned facing the encoder. The sensor support is connected to the rotating wheel through a bearing assembly, and is always non-rotated by a detent structure constructed between the sensor support and the stationary wheel. It is maintained.

  In the present invention, the sensor support body has a disk shape that covers the entire hollow cylindrical body side end portion formed on the vehicle body side of the stationary wheel and can seal the inside of the bearing from the outside of the bearing. Yes. The detent structure includes at least one convex portion that protrudes from the sensor support toward the stationary wheel, and a concave portion that is formed on the stationary wheel so as to be able to accommodate the convex portion. The sensor support is always maintained in a non-rotating state during rotation of the rotating wheel. Furthermore, the bearing assembly includes a housing portion formed on the sensor support body so as to face the rotating wheel, and a bearing interposed between the housing portion and the rotating wheel. It is comprised so that relative rotation is possible via a bearing. A sealing member for sealing the gap is interposed in the gap between the sensor support and the vehicle body side end of the stationary wheel.

  According to the bearing unit of the present invention, even if a relative inclination occurs between the stationary wheel and the rotating wheel, the gap (gap) between the encoder and the sensor can always be maintained constant, so that the wheel Can be measured with high accuracy.

  Hereinafter, a bearing unit according to an embodiment of the present invention will be described with reference to the accompanying drawings. Since this embodiment is an improvement of the rotation detection mechanism of the bearing unit (FIG. 3) as described above, only the improved portion will be described below. In the drawings used in the description of the improved portion, the same components as those of the above-described bearing unit (FIG. 3) are denoted by the same reference numerals, and the description thereof is omitted.

  As shown in FIGS. 1A to 1C, in the rotation detection mechanism of the present embodiment, the encoder 20 is the same as the rotation detection mechanism of FIG. And is configured to rotate together with the rotating wheel 4. On the other hand, the sensor 22 is supported by the sensor support 26 in a state of being positioned facing the encoder 20. In this case, the sensor support 26 is connected to the rotating wheel 4 via a bearing assembly, and is always provided by a detent structure constructed between the sensor support 26 and the stationary wheel (outer ring) 2. It is maintained in a non-rotating state.

  Further, in the present embodiment, the vehicle body side end 2n-2 formed on the vehicle body side of the stationary wheel (outer ring) 2 has a hollow cylindrical shape, and the sensor support 26 has the vehicle body side end portion. 2n-2 is covered so that the inside of the bearing can be sealed from the outside of the bearing. Specifically, the sensor support 26 has a disk shape that can be disposed inside the hollow cylindrical body-side end 2n-2, and the sensor support 26 and the vehicle-side end 2n-2 Are positioned in a non-contact state with each other along the circumferential direction.

  In this case, in a state where the sensor support body 26 is disposed inside the vehicle body side end portion 2n-2, a gap between the outer periphery of the sensor support body 26 and the inner periphery of the vehicle body side end portion 2n-2 extends along the circumferential direction. A continuous gap H is formed, but by reducing the gap H, a kind of labyrinth can be configured. Thus, foreign matter (for example, water, dust, etc.) does not enter the bearing through the gap H, and lubricant (for example, oil, grease) does not leak to the outside of the bearing.

  Moreover, as a material of the sensor support body 26, for example, a metal material or a resin material can be applied. However, the bearing unit in which the sensor support body 26 is used is used in an environment that is directly exposed to a difference in temperature. Is done. Therefore, in such an environment, the sensor support 26 is preferably made of a material having excellent durability and heat resistance so that the inside of the bearing can be sealed from the outside of the bearing for a long time. In addition, since it can select arbitrarily as a material excellent in durability and heat resistance, for example according to the intended purpose and use environment of a bearing unit, it does not specifically limit here.

  Here, the bearing assembly includes a housing portion 26 h formed on the sensor support 26 so as to face the rotating wheel 4, and a bearing 28 interposed between the housing portion 26 h and the rotating wheel 4. In the present embodiment, a shaft body 30 extending along the center of rotation is fixed to the hub (spindle) 12, and the shaft body 30 together with the hub 12 and the rotating wheel component 16 has a rotating shaft 4. Is configured. The shaft body 30 is also a component of the bearing assembly. In this case, as a method of fixing the shaft body 30 to the hub 12, for example, a method such as screwing, welding, fitting, or adhesion can be applied. Here, as an example, one end 30 t of the shaft body 30 is connected to the hub 12. The shaft body 30 is fixed to the hub 12 by being press-fitted into the fixing hole 12 h formed in FIG.

  The housing portion 26h has a hollow annular shape that is continuous in the circumferential direction so as to face the outer periphery of the rotating shaft 4 (that is, the shaft body 30), and the housing portion 26h is interposed between the housing portion 26h and the shaft body 30. A plurality of (for example, two) bearings 28 are interposed. In this case, each bearing 28 rotates between the inner ring 28a fixed to the outer periphery of the shaft body 30, the outer ring 28b fixed to the inner periphery of the housing portion 26h so as to face the inner ring 28a, and the inner and outer rings 28a, 28b. And a plurality of rolling elements 28c incorporated in a freely movable manner. Note that balls or rollers can be applied as the rolling element 28c, but balls are illustrated in the drawings.

  On the other hand, the detent structure includes a convex portion 32 protruding from the sensor support 26 toward the stationary ring (outer ring) 2 and a concave portion 34 formed in the stationary ring 2 so as to be able to accommodate the convex portion 32. Has been. In this case, in a state where the convex portion 32 is accommodated in the concave portion 34, the convex portion 32 is prevented from being detached from the concave portion 34. Therefore, the sensor support 26 is always kept during rotation of the rotating shaft 4 (shaft body 30). It is maintained in a non-rotating state.

  Here, the number and position of the convex portions 32 can be arbitrarily set according to the size and shape of the sensor support 26, for example, and thus are not particularly limited. The structure which protruded from the outer periphery of the support body 26 is shown. In addition, as the shape of the convex portion 32, for example, a rectangular shape, a triangular shape, a truncated cone shape, an arc shape, or the like can be applied, but here, as an example, the convex portion 32 having a rectangular cross section is assumed. . On the other hand, the recesses 34 are arbitrarily set according to the number, position, or shape of the projections 32, and are not particularly limited. In short, the projections 32 are not easily detached from the recesses 34. Any configuration is acceptable.

  According to such a configuration, the sensor support 26 and the rotating wheel 4 (shaft body 30) are coupled to each other via the bearings 28 of the bearing assembly so as to be relatively rotatable, but the convex portion 32 is accommodated in the concave portion 34. Even if a rotational force is applied to the sensor support 26 via the bearings 28 during rotation of the rotating shaft 4 (shaft body 30), the sensor support 26 is always kept in a non-rotating state. Can do.

  As described above, according to the present embodiment, both the encoder 20 and the sensor 22 are connected to the rotating wheel (inner ring) 4, so that an external force acts on the bearing unit from the wheel side when the vehicle travels, and the stationary wheel (outer ring). Even when a relative inclination occurs between the rotating wheel (inner ring) 4 and the rotating wheel (inner ring) 4, the gap (gap) G between the encoder 20 and the sensor 22 is always kept constant without being affected by it. Can do.

  For example, when the rotating wheel (inner ring) 4 is tilted, the encoder 20 fixed to the rotating wheel 4 (rotating wheel component 16) by the support member 24 is inclined at the same angle in the same direction as the rotating wheel 4 is tilted. Tilt. On the other hand, since the sensor 22 is connected to the rotating wheel 4 from the sensor support 26 via the bearing assembly, the sensor 22 is inclined at the same angle in the same direction as the encoder 20 as the rotating wheel 4 is inclined. In this case, since the positional relationship between the encoder 20 and the sensor 22 does not change at all, the gap (gap) G between the two can always be kept constant. This makes it possible to measure the rotation speed of the maintenance wheel with high accuracy.

  Further, according to the present embodiment, the sensor support 26 can be used as the cover (cap) 10b of the above-described bearing unit (FIG. 3), so that the sealability inside the bearing can be kept constant without increasing the number of parts. At the same time, it is possible to realize a low-cost bearing unit capable of measuring the rotational speed of the wheel with high accuracy. Depending on the environment during rotation of the rotating shaft 4 (shaft body 30), foreign matter may enter from the gap H between the outer periphery of the sensor support 26 and the vehicle body side end 2n-2 of the stationary wheel (outer ring) 2. There is also a risk that the lubricant may leak. In that case, it is preferable to interpose a sealing member 36 for sealing the gap H. In this case, as the sealing member 36, for example, an existing seal such as an O ring or an X ring may be applied.

In addition, this invention is not limited to embodiment mentioned above, The same effect is realizable also as each following modification.
As a first modification, the bearing unit shown in FIG. 2A is configured by covering a gap H between the outer periphery of the sensor support 26 and the inner periphery of the vehicle body side end 2n-2 with a diaphragm 38. Yes. In this case, the diaphragm 38 is formed by continuously expanding and contracting elastically deformable rubber or resin, for example, in the form of a hollow cylinder, one side of which is connected to the outer periphery of the sensor support 26 and the other side. Is connected to the inner periphery of the vehicle body side end 2n-2, so that the gap H can be completely sealed.

  According to this modification, by using the diaphragm 38, a waterproof effect can be secured at the same time as an anti-rotation effect. Further, since it is not necessary to form the rotation prevention mechanism (the convex portion 32 and the concave portion 34) as in the above-described embodiment, it is possible to realize a lower-cost bearing unit. Since other configurations and effects are the same as those of the above-described embodiment, description thereof is omitted.

  Incidentally, in the above-described embodiment and the first modification, the encoder 20 and the sensor 22 are opposed to each other in the axial direction. Instead, this is shown in FIG. 2B as a second modification. In the bearing unit, the encoder 20 and the sensor 22 are opposed to each other in the radial direction. In this case, the configuration in which the encoder 20 and the sensor 22 are opposed to each other can be arbitrarily set, and is not particularly limited. However, as an example in the drawing, the encoder 20 is disposed outward along the circumferential direction. The sensor 22 is positioned on the side periphery of the sensor support 26 so as to face each other.

  Further, in the bearing assembly of this modification, the above-described shaft body 30 (FIGS. 1A and 2A) is not required, and the housing portion 26h is formed to face the rotating wheel component 16 of the rotating wheel 4. In addition, a plurality of (for example, two) bearings 28 are interposed between the housing portion 26 h and the rotating wheel component 16. In this case, although not particularly illustrated, each bearing 28 is provided between an inner ring fixed to the outer periphery of the rotating wheel component 16, an outer ring fixed to the inner periphery of the housing portion 26h so as to face the inner ring, and the inner and outer rings. And a plurality of rolling elements incorporated so as to freely roll. In addition, a ball or a roller can be applied as the rolling element. According to this modification, since the shaft body 30 is not required, the number of parts can be reduced, and the trouble of fixing the shaft body 30 to the hub (spindle) 12 is not required. It can be realized. Since other configurations and effects are the same as those of the above-described embodiment, description thereof is omitted.

(a) is a cross-sectional view showing the configuration of a bearing unit according to an embodiment of the present invention, (b) is a plan view of the bearing unit of FIG. Sectional drawing which expands and shows the positional relationship of an encoder and a sensor. (a) is sectional drawing which shows the structure of the bearing unit which concerns on the 1st modification of this invention, (b) is sectional drawing which shows the structure of the bearing unit which concerns on the 2nd modification of this invention. Sectional drawing which shows the structure of the conventional bearing unit.

Explanation of symbols

2 Stationary wheel (outer ring)
4 Rotating wheel (inner ring)
6,8 Rolling element 20 Encoder 22 Sensor 26 Sensor support 28 Bearing (Bearing assembly)
32 Convex (non-rotating structure)
34 Concavity (non-rotating structure)

Claims (5)

Between the stationary wheel and the rotating wheel, a stationary wheel that is fixed to the vehicle body and is maintained in a non-rotating state at all times, a rotating wheel that is provided opposite to the stationary wheel and that is connected to the wheel side and rotates together with the wheel. A bearing unit comprising a plurality of rolling elements incorporated rotatably and a rotation detection mechanism for detecting the rotation speed of the wheel,
The rotation detection mechanism is provided with an encoder that is connected to the rotating wheel and rotates together with the rotating wheel, and a sensor that detects information characteristics recorded in the encoder, and the sensor is positioned facing the encoder. Supported by the sensor support,
The sensor support is connected to the rotating wheel via a bearing assembly, and is always kept in a non-rotating state by a detent structure constructed between the sensor support and the stationary wheel. Features bearing unit.   The sensor support body has a disk shape that covers the entire hollow cylindrical body side end portion formed on the vehicle body side of the stationary wheel and can seal the inside of the bearing from the outside of the bearing. The bearing unit according to claim 1.   The anti-rotation structure includes at least one convex portion that protrudes from the sensor support toward the stationary wheel, and a concave portion that is formed on the stationary wheel so as to be able to accommodate the convex portion. 3. The bearing unit according to claim 1, wherein the sensor support is always kept in a non-rotating state during rotation of the rotating wheel in the state of being accommodated in the bearing unit.   The bearing assembly includes a housing portion formed on the sensor support so as to face the rotating wheel, and a bearing interposed between the housing portion and the rotating wheel. The sensor support and the rotating wheel include a bearing. The bearing unit according to any one of claims 1 to 3, wherein the bearing unit is configured to be relatively rotatable.   The bearing unit according to any one of claims 2 to 4, wherein a sealing member for sealing the gap is interposed in the gap between the sensor support and the vehicle body side end of the stationary wheel. .

Images