JP2012122789A - Wheel bearing with rotation detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wheel bearing with a rotation detection device capable of preventing a magnetic encoder from being damaged due to biting of a foreign matter and providing a sufficient rotation detection accuracy.SOLUTION: A wheel bearing has an outer member 1 and an inner member 2 which are relatively rotatable via a rolling element 5, and supports a wheel rotatably on a vehicle body. An annular magnetic encoder 22 in which a plurality of pairs of magnetic poles are circumferentially arranged at equal intervals is provided on one end part in an axial direction of a rotation side member among the outer member 1 and the inner member 2 so as to be concentric with the rotation side member. A sensor 23 for detecting the pairs of magnetic poles of the magnetic encoder 22 is provided confronting the magnetic encoder 22. A protective cover 18 is provided which is interposed between the magnetic encoder 22 and the sensor 23 and protects the magnetic encoder 22. Multiplication means 24 is provided which multiplies the phase of the pair of magnetic poles from the output of the sensor.

Description

  The present invention relates to a wheel bearing with a rotation detection device equipped with a rotation detection device.

As this type of wheel bearing with a rotation detection device, as shown in FIG. 6, among the outer member 101 and the inner member 102 that are relatively rotatable via a rolling element (not shown), An annular magnetic encoder 111 is attached concentrically to the inboard side end of the inner member 102 and the inboard side of the outer member 101 serving as a fixed member of the outer member 101 and the inner member 102. A device in which a protective cover 113 facing the magnetic encoder 111 on the outer side of the magnetic encoder 111 is attached to the end is proposed (for example, Patent Document 1). A sensor 112 for detecting the magnetic pole of the magnetic encoder 111 is opposed to the magnetic encoder 111 via a predetermined air gap with the protective cover 113 interposed therebetween, thereby detecting the rotational speed of the inner member 102.
As described above, by disposing the protective cover 113 on the outer side of the magnetic encoder 111, it is difficult for foreign matters such as stones to be caught between the magnetic encoder 111 and the sensor 112, and even if the biting occurs, the magnetic encoder 111 can be prevented from being damaged.

JP 2002-267680 A

  However, in the case of the above configuration, since the protective cover is interposed between the magnetic encoder and the sensor, the distance (air gap) from the surface of the magnetic encoder to the sensor increases, and the magnetic flux density of the magnetic encoder detected by the sensor increases. There is a problem of lowering. In order to avoid a decrease in the detected magnetic flux density, the air gap may be narrowed or the magnetic encoder magnetic flux density may be increased, but there is a limit to narrowing the air gap.

The following countermeasures can be considered to increase the magnetic flux density of the magnetic encoder.
(1) Increasing the amount of magnetic powder (ferrite magnet), which is a magnetic pole material of a magnetic encoder. (2) The magnetic powder that is the material of the magnetic encoder magnetic pole is changed to a rare earth magnet.
(3) Increase the size of the magnetic encoder.
(4) Reduce the number of magnetic encoder magnetic poles.
Among these, the countermeasures (1) to (3) are difficult to realize because they increase costs and increase the bearing size.
In the measure (4) for reducing the number of magnetic poles, the circumferential width (area) of one magnetic pole to be magnetized is increased, so that the magnetization intensity is increased. For example, if the number of magnetic pole pairs (N magnetic pole and S magnetic pole pairs) is 48 (N magnetic pole is 48, S magnetic pole is 48), the magnetization strength is improved by about 2.2 times. Thereby, even if an air gap spreads, the magnetic flux density detected with a sensor does not fall. However, when the number of magnetic poles is reduced in this way, the number of output pulses obtained by one rotation of the wheel is reduced, which causes a new problem that the detection accuracy of the wheel rotation speed is deteriorated.

  An object of the present invention is to provide a wheel bearing with a rotation detection device that can prevent damage to a magnetic encoder due to foreign object biting and can obtain sufficient rotation detection accuracy.

The wheel bearing with a rotation detection device of the present invention includes an outer member and an inner member that are rotatable relative to each other via a rolling element, and in the wheel bearing that rotatably supports the wheel with respect to the vehicle body, An annular magnetic encoder in which a plurality of magnetic pole pairs arranged in the circumferential direction are equally arranged at one axial end portion of the rotation side member of the outer member and the inner member is provided concentrically with the rotation side member. A wheel bearing with a rotation detection device provided with a sensor for detecting the magnetic pole pair of the magnetic encoder opposite to the magnetic encoder, and provided with a protective cover interposed between the magnetic encoder and the sensor to protect the magnetic encoder. A multiplication means for multiplying the phase of the magnetic pole pair from the output of the sensor is provided.
According to this configuration, since the protective cover is provided between the magnetic encoder and the sensor to protect the magnetic encoder, it is difficult for foreign matter to be caught between the magnetic encoder and the sensor, and even if the biting occurs. It is possible to prevent the magnetic encoder from being damaged. In the rotation detector, the phase of the magnetic pole pair of the magnetic encoder is multiplied from the output of the sensor by the multiplication means. For this reason, the protective cover interposed between the magnetic encoder and the sensor increases the air gap between the magnetic encoder and the sensor, and the magnetic flux density of the magnetic encoder detected by the sensor decreases. Even if it is prevented by reducing the number of magnetic pole pairs of the encoder, sufficient rotation detection accuracy can be obtained. As a result, damage to the magnetic encoder due to foreign matter biting can be prevented, and sufficient rotation detection accuracy can be obtained.

  In this invention, the axial direction one end part of the rotation side member provided with the said magnetic encoder may be an inboard side edge part of the bearing for wheels.

  In the present invention, the protective cover may be provided on a fixed member of the outer member and the inner member.

  In the present invention, the number of magnetic pole pairs of the magnetic encoder may be 24, and the multiplication number of the multiplication means may be doubled. In this case, the magnetic flux density of the magnetic pole is about 2.2 times that when the number of magnetic pole pairs is 48. Therefore, the magnetic flux density detected by the sensor for the protective cover does not decrease, and the detection accuracy is reduced by half the number of magnetic pole pairs. Can be prevented by doubling the multiplication number of the multiplication means.

  In the present invention, there may be provided pulse output means for outputting a pulse having a predetermined magnification by inputting the output of the multiplication means or inputting the output of the multiplication means and the detection output of the sensor.

  The pulse output means may generate all the pulses to be output from the output of the multiplication means.

  Further, the multiplication factor of the pulse output from the pulse output means may be set to 2.

  In the present invention, a magnification changing means for changing the magnification setting of the pulse output from the pulse output means from the outside may be provided. Here, “external” is external to the pulse output means, and the pulse magnification setting of the pulse output means can be changed from the external to the rotation detection device, for example, means provided in an electric control unit mounted on the vehicle. You may do it. Thereby, for example, a pulse having a magnification corresponding to a change in the rotational speed due to a change in the vehicle traveling speed or the like can be output during use.

  In this invention, the sensor is composed of a line sensor in which sensor elements are arranged along the arrangement direction of the magnetic pole pairs of the magnetic encoder, and generates a two-phase sinusoidal signal by calculation to detect a phase in one magnetic pole. It may be what you do. In the case of this configuration, since the influence of distortion and noise of the magnetic pole pattern is reduced, the phase of the magnetic encoder can be detected with high accuracy.

In the present invention, the pulses of at least one type of magnification output from the pulse output means may be A phase and B phase difference signals having phases different from each other by 90 degrees.
As described above, by outputting the phase difference signals of the A phase and the B phase that are 90 degrees different from each other as the rotation pulse signal having the same magnification, it is possible to detect the rotation direction and to detect the forward / reverse of the vehicle. it can.

  In the present invention, the sensor, the multiplication unit, and the pulse output unit may be integrated and integrated in a common integrated circuit. This integrated circuit is an IC chip. As a result, the rotation detection device can be compactly mounted on the wheel bearing, and the weight can be reduced.

  The wheel bearing with a rotation detection device of the present invention includes an outer member and an inner member that are rotatable relative to each other via a rolling element, and in the wheel bearing that rotatably supports the wheel with respect to the vehicle body, An annular magnetic encoder in which a plurality of magnetic pole pairs arranged in the circumferential direction are equally arranged at one axial end portion of the rotation side member of the outer member and the inner member is provided concentrically with the rotation side member. A wheel bearing with a rotation detection device provided with a sensor for detecting the magnetic pole pair of the magnetic encoder opposite to the magnetic encoder, and provided with a protective cover interposed between the magnetic encoder and the sensor to protect the magnetic encoder. Since the multiplication means for multiplying the phase of the magnetic pole pair from the output of the sensor is provided, it is possible to prevent damage to the magnetic encoder due to foreign matter biting and to obtain sufficient rotation detection accuracy. .

It is a figure showing combining the sectional view of the wheel bearing with a rotation detector concerning one embodiment of this invention, and the block diagram of the conceptual composition of the detection system. It is a partial expanded sectional view of the wheel bearing. (A) is a half front view of the magnetic encoder with 48 magnetic pole pairs, and (B) is a half front view of the magnetic encoder with 24 magnetic pole pairs. It is a block diagram which shows schematic structure of a rotation detection apparatus. It is a block diagram which shows the example of 1 structure of the magnetic sensor in the rotation detection apparatus. It is a partial expanded sectional view of a prior art example.

  An embodiment of the present invention will be described with reference to FIGS. This embodiment is a third generation inner ring rotating type and is applied to a wheel bearing for supporting a driven wheel. In this specification, the side closer to the outer side in the vehicle width direction of the vehicle when attached to the vehicle is referred to as the outboard side, and the side closer to the center of the vehicle is referred to as the inboard side.

  As shown in a sectional view in FIG. 1, the bearing for the wheel bearing with the rotation detecting device is opposed to the outer member 1 in which a double row rolling surface 3 is formed on the inner periphery, and the respective rolling surfaces 3. The inner member 2 has a rolling surface 4 formed on the outer periphery, and the outer member 1 and the double row rolling elements 5 interposed between the rolling surfaces 3 and 4 of the inner member 2. This wheel bearing is a double-row angular ball bearing type, and the rolling elements 5 are made of balls and are held by a cage 6 for each row. The rolling surfaces 3 and 4 have an arc shape in cross section, and are formed so that the ball contact angle is aligned with the back surface. The outboard side end in the bearing space between the outer member 1 and the inner member 2 is sealed by a seal 7.

  The outer member 1 is a fixed side member, and has a vehicle body mounting flange 1a attached to a knuckle (not shown) in the suspension device of the vehicle body on the outer periphery, and the whole is an integral part. The flange 1a is provided with screw holes 14 for attaching knuckles at a plurality of locations in the circumferential direction, and knuckle bolts (both not shown) inserted into the bolt insertion holes of the knuckle from the inboard side are screwed into the screw holes 14. Thus, the vehicle body mounting flange 1a is attached to the knuckle. The inner member 2 is a rotating side member, and includes a hub wheel 9 having a hub flange 9a for wheel mounting, and an inner ring 10 fitted to the outer periphery of the end portion on the inboard side of the shaft portion 9b of the hub wheel 9. And become. The hub wheel 9 and the inner ring 10 are formed with the rolling surfaces 4 of the respective rows. An inner ring fitting surface 12 having a small diameter with a step is provided on the outer periphery of the inboard side end of the hub wheel 9, and the inner ring 10 is fitted to the inner ring fitting surface 12. The hub flange 9a is provided with press-fitting holes 15 for the hub bolts 11 at a plurality of locations in the circumferential direction. In the vicinity of the base portion of the hub flange 9a of the hub wheel 9, a cylindrical pilot portion 13 for guiding a wheel and a braking component (not shown) protrudes toward the outboard side.

  An annular magnetic encoder 22 having an L-shaped cross section is fitted to the outer periphery of the end portion on the inboard side of the inner member 2 that is a rotation side member. As shown in an enlarged view in FIG. 2, the magnetic encoder 22 has a circumferential direction of a side surface facing the inboard side of the upright plate portion 29 b extending from one end of the cylindrical portion 29 a of the L-shaped cored bar 29 a to the outer diameter side. In addition, a plurality of magnetic pole pairs 22c (FIG. 4) are magnetized by arranging them at equal positions, and the cylindrical portion 29a of the core metal 29 is fitted to the outer periphery of the inboard side end portion of the inner member 2. It is done. The magnetic sensor 23 that detects the magnetic poles N and S of the magnetic encoder 22 faces the magnetic pole surface of the magnetic encoder 22 (that is, the standing plate portion 29b of the core metal 29) in the axial direction via a predetermined air gap G. The magnetic encoder 22 is disposed on the inboard side of the mounting position. That is, here, the magnetic encoder 22 is an axial type. The magnetic sensor 23 detects the rotation of the inner member 2 by detecting the magnetic poles N and S of the magnetic encoder 22. However, the magnetic encoder 22 is not limited to such an axial type, but may be a radial type in which magnetic pole pairs are arranged at equal positions on the circumferential surface. In this case, the magnetic sensor 23 is disposed on the outer diameter side of the inner member 2 so as to face the magnetic pole surface of the magnetic encoder 22 in the radial direction via a predetermined air gap.

  As shown in FIG. 4, the magnetic encoder 22 and the magnetic sensor 23, and a multiplication means 24 for generating a multiplied pulse b by multiplying the phase in the magnetic pole pair 22c of the magnetic encoder 22 by a multiplication number N from the output of the magnetic sensor 23. And rotation for detecting rotation of the inner member 2 of the wheel bearing, that is, rotation of the wheel, by the pulse output means 25 for outputting a rotation pulse having a magnification determined based on the multiplication pulse b generated from the multiplication means 24. A detection device 21 is configured.

  A protective cover 18 made of a non-magnetic material facing the magnetic pole surface of the magnetic encoder 22 is disposed on the bearing outer side of the magnetic encoder 22, that is, between the magnetic encoder 22 and the magnetic sensor 23. The protective cover 18 made of nonmagnetic material may be a metal plate such as nonmagnetic stainless steel or a resin material, for example. The magnetic sensor 23 detects the magnetic pole of the magnetic encoder 22 through the protective cover 18. As shown in FIG. 2, the protective cover 18 is formed into a bottomed cap shape having a disk-like bottom plate portion 18 a and a cylindrical portion 18 b on the outer periphery thereof, and the cylindrical portion 18 b is formed on the inboard side of the outer member 1. The outer member 1 is attached by being fitted into the inner diameter surface of the end portion in a press-fitted state.

  Here, the magnetic sensor 23 includes line sensors 23A and 23B and an operational amplifier 30 as shown in FIG. The line sensors 23 </ b> A and 23 </ b> B are configured by arranging a plurality of magnetic sensor elements 23 a so as to be aligned along the arrangement direction of the magnetic poles of the magnetic encoder 22. The operational amplifier 30 includes a plurality of adder circuits 31, 32, 33, 34 and an inverter 35. FIG. 5A is a waveform diagram in which one magnetic pole section of the magnetic encoder 22 is converted into a magnetic field strength. In this case, the first line sensor 23A is arranged in association with the 90-degree phase section of the 180-degree phase section in FIG. 5A, and the second line sensor 23B is the remaining 90-degree phase section. It is arranged in association with. With such an arrangement, the signal S1 obtained by adding the detection signal of the first line sensor 23A by the addition circuit 31 and the signal S2 obtained by adding the detection signal of the second line sensor 23B by the addition circuit 32 are added separately. By adding in the circuit 33, a sin signal corresponding to the magnetic field signal as shown in FIG. 5C is obtained. Further, the signal S1 and the signal S2 via the inverter 35 are added by another adding circuit 34 to obtain a cos signal corresponding to the magnetic field signal as shown in FIG. The position in the magnetic pole can be detected from the two-phase output signal thus obtained.

  When the magnetic sensor 23 is configured by the line sensors 23A and 23B as described above, the influence of the distortion and noise of the magnetic field pattern is reduced, so that the phase of the magnetic encoder 22 can be detected with high accuracy.

  As another example of the magnetic sensor 23, when the pitch λ of one magnetic pole pair of the magnetic encoder 22 is one cycle, the magnetic sensors 23 are arranged apart from each other in the arrangement direction of the magnetic poles so that the phase difference is 90 degrees (λ / 4). The magnetic pole phase (φ = tan-1 (sinφ / cos φ)) is multiplied from the two-phase signals (sinφ, cosφ) obtained by these two magnetic sensor elements. It is good also as what calculates.

  In FIG. 4, a pulse output means 25 is a means for outputting a rotation pulse having a magnification determined from a multiplication pulse b which is phase data in the magnetic pole pair 22c inputted from the multiplication means 24. When the multiplication number N in the multiplication means 24 is, for example, twice, the pulse output means 25 outputs a rotation pulse having a multiplication factor (× 2) as it is. That is, the position (phase) within the magnetic pole pair 22c of the magnetic encoder 22 is detected by two rotation pulses. In this case, assuming that the number of magnetic pole pairs of the magnetic encoder 22 is 24 (an example is shown in FIG. 3B), the pulse output means 25 outputs 48 rotation pulses. In this example, the magnetic flux density of the magnetic poles is about 2.2 times that when the number of magnetic pole pairs is 48 (an example is shown in FIG. 3A), and therefore the magnetic flux detected by the magnetic sensor 23 for the protective cover 18. The density does not decrease, and a decrease in detection accuracy due to halving of the number of magnetic pole pairs can be prevented by doubling the multiplication number N of the multiplication means 24.

  The pulse output means 25 may output a rotation pulse having a predetermined magnification by inputting the detection output of the magnetic sensor 22 in addition to the output of the multiplication means 24. Further, a plurality of types of rotation pulses having different magnifications may be output from the pulse output means 25. Alternatively, the A-phase rotation pulse and the B-phase rotation pulse whose phases are different from each other by 90 degrees may be individually output from the pulse output means 25 as rotation pulse signals having the same magnification. As described above, the rotation direction can be detected by outputting the phase difference signals of the A phase and the B phase, which are 90 degrees different from each other as the rotation pulse signal having the same magnification, and the vehicle can be detected as moving forward or backward. it can.

  Here, the magnification of the rotation pulse output from the pulse output means 25 is fixed to 2 times. However, as indicated by a virtual line in FIG. It is also possible to change the magnification of the rotation pulse output by the command from Thereby, for example, a rotation pulse with a magnification corresponding to a change in the rotation speed due to a change in the vehicle running speed or the like can be output during use.

  The magnetic sensor 23, the multiplication unit 24, and the pulse output unit 25 are integrated and integrated in a common integrated circuit 28, and an output terminal from which a rotation pulse is output is provided. The integrated circuit 28 consists of an IC chip. As a result, the rotation detector 21 can be mounted compactly on the wheel bearing, and the weight can be reduced.

  According to this wheel bearing with a rotation detection device, the protective cover 18 is provided between the magnetic encoder 22 and the magnetic sensor 23 so as to protect the magnetic encoder 22. It is difficult for foreign matter to bite into the magnetic encoder 22, and even if the biting occurs, the magnetic encoder 22 can be prevented from being damaged. Further, in the rotation detection device 1, the multiplication unit 24 generates a high-magnification multiplied pulse b obtained by multiplying the phase in the magnetic pole pair 22 c of the magnetic encoder 22 from the output of the magnetic sensor 23, and a pulse corresponding to the multiplied pulse b. A high-magnification rotation pulse is output from the output means 25. For this reason, because of the protective cover 18 interposed between the magnetic encoder 22 and the magnetic sensor 23, the air gap G between the magnetic encoder 22 and the magnetic sensor 23 becomes large, and the magnetic encoder detected by the magnetic sensor 23 is detected. Even if the decrease in the magnetic flux density of 22 is prevented by reducing the number of magnetic pole pairs of the magnetic encoder 22, sufficient rotation detection accuracy can be obtained.

In the above-described embodiment, the case where the magnetic encoder 22 is provided on the inboard side of the wheel bearing has been described. However, the present invention also applies to the case where the magnetic encoder 22 is provided on the outboard side of the wheel bearing. Can be applied to.
In the above-described embodiment, the case where the inner member 2 is a rotation side member has been described. However, the present invention can also be applied to a wheel bearing in which the outer member is a rotation side member. The magnetic encoder 22 is provided on the outer member.
In the above-described embodiment, the case where the present invention is applied to a third generation type wheel bearing has been described. However, the present invention is for a first or second generation type wheel in which the bearing portion and the hub are independent parts. The present invention can also be applied to a bearing or a fourth-generation type wheel bearing in which a part of the inner member is composed of an outer ring of a constant velocity joint. Moreover, this wheel bearing with a rotation detection device can be applied to a wheel bearing for a driving wheel, and can also be applied to each generation type tapered roller type wheel bearing.

DESCRIPTION OF SYMBOLS 1 ... Outer member 2 ... Inner member 5 ... Rolling body 18 ... Protective cover 21 ... Rotation detection apparatus 22 ... Magnetic encoder 22c ... Magnetic pole pair 23 ... Magnetic sensor 23A, 23B ... Line sensor 24 ... Multiplication means 25 ... Pulse output means 27: Magnification changing means 28 ... Integrated circuit

Claims (11)

In a wheel bearing that includes an outer member and an inner member that are rotatable relative to each other via a rolling element, and that rotatably supports the wheel with respect to the vehicle body,
An annular magnetic encoder in which a plurality of magnetic pole pairs arranged in the circumferential direction are equally arranged at one axial end portion of the rotation side member of the outer member and the inner member is provided concentrically with the rotation side member. A wheel bearing with a rotation detection device provided with a sensor for detecting the magnetic pole pair of the magnetic encoder opposite to the magnetic encoder, and provided with a protective cover interposed between the magnetic encoder and the sensor to protect the magnetic encoder. ,
A wheel bearing with a rotation detection device, characterized in that a multiplication means for multiplying the phase of the magnetic pole pair from the output of the sensor is provided.   The wheel bearing with a rotation detecting device according to claim 1, wherein one end portion in the axial direction of the rotation side member provided with the magnetic encoder is an inboard side end portion of the wheel bearing.   The wheel bearing with a rotation detector according to claim 1 or 2, wherein the protective cover is provided on a fixed side member of the outer member and the inner member.   The wheel bearing with a rotation detector according to any one of claims 1 to 3, wherein the number of magnetic pole pairs of the magnetic encoder is 24 and the multiplication number of the multiplication means is twice.   5. The pulse according to claim 1, wherein an output of the multiplying unit is input, or an output of the multiplying unit and a detection output of the sensor are input to output a pulse having a predetermined magnification. Wheel bearing with rotation detector provided with output means.   6. The wheel bearing with rotation detection device according to claim 5, wherein the pulse output means generates all the pulses to be output from the output of the multiplication means.   The wheel bearing bearing with a rotation detecting device according to claim 6, wherein a multiplication factor of a pulse output from said pulse output means is 2.   The wheel bearing with a rotation detecting device according to any one of claims 5 to 7, further comprising a magnification changing means for changing a magnification setting of a pulse output from the pulse output means from outside.   9. The sensor according to claim 1, wherein the sensor is configured by a line sensor in which sensor elements are arranged along an arrangement direction of magnetic pole pairs of the magnetic encoder, and generates a two-phase sinusoidal signal by calculation. A wheel bearing with a rotation detection device that detects a phase in one magnetic pole.   10. The rotation detection device according to claim 5, wherein at least one type of magnification pulse output from the pulse output means is used as an A-phase and B-phase phase difference signal having a phase difference of 90 degrees. Bearings with wheels.   11. The wheel bearing with a rotation detecting device according to claim 5, wherein the sensor, the multiplying unit, and the pulse output unit are integrated and integrated in a common integrated circuit.

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