JPH1123594A - Annular speed sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an annular wheel speed sensor capable of outputting an electric signal of high level even in the case of relative low wheel speed. SOLUTION: This speed sensor is constituted of a magnetic tone ring 32 having magnetic fields in the axial direction and in the radial direction, and a stator 34 having a detecting part detecting the magnetic fields in the axial direction and in the radial direction of the tone ring during rotation of the tone ring. In this sensor, because variation of a gap between the tone ring and the stator can be restrained to the minimum, wheel speed can be correctly measured, and because it can be built in a hub bearing device, a fitting space is hardly required. The hub bearing mechanism is provided with a seal means 62 protecting the sensor from an external adverse effect.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a rotational speed sensor,
In particular, the present invention relates to a sensor capable of detecting a rotation speed of a vehicle wheel.

[0002]

2. Description of the Related Art In various situations, it may be necessary to measure the relative rotational speed of a machine component. For example, a rotation sensor is used to measure the rotation speed of a main shaft of a jet engine or a spindle of a machine tool. A rotation sensor is also used in an anti-lock brake system (ABS), which is increasingly equipped on a recent automobile. The ABS prevents the wheels from locking when a sudden brake is applied, thereby maintaining the running stability and direction of the vehicle. The ABS always needs a wheel speed sensor that sends a signal indicating the rotation of the wheel to the ABS control unit. Most passenger cars have rotation sensors on all four wheels. Based on the signal from the rotation sensor,
The control unit of the ABS determines whether the wheels are locked or is about to be locked, and performs anti-lock control based on the determination. The wheel speed sensor is
It is also used as an input to a traction control device that prevents the drive wheels from spinning during acceleration.

[0003] A wide variety of wheel speed sensors for ABS are currently known. Among them, the most widespread is a sensor including a non-rotating portion (stator) and a rotating portion (rotor) provided close to the stator. The rotating part, also called a "tone ring," has a detected part that is detected by the non-rotating part during rotation. For example, ferromagnetic teeth formed on the gears, magnetic poles having opposite magnetism formed on the rotating portion, and the like are used as the detected portion. The non-rotating part detects passage of the detected part formed on the rotating tone ring, and outputs a detection result as a signal.

As transducers, there are a variable reluctance type device, a Hall effect device, a magnetostrictive device and the like. Most transducers detect a magnetic field (a changing magnetic field). Variable reluctance transducers are called "passive" sensors because they generate a voltage without receiving power from an external power source. On the other hand, "active" sensors, such as Hall effect devices, are activated by an externally applied alternating voltage and produce an output in response to a magnetic field passing through the device.

One problem with today's wheel speed sensors is that the strength of the magnetic field tends to change due to changes in the size of the air gap between the rotor and the stator. There is a magnetic field sensor in which a tone ring rotates together with a wheel bearing. Usually, the magnetic pole of the tone ring (rotor) of this type of sensor or the detection part made of ferromagnetic material is
It is formed so as to extend in the axial direction or the radial direction. The detection unit of the stator is provided so as to face the upper or lower surface of the tone ring to detect magnetic poles in the axial direction. In this case, since the tone ring rotates together with the wheel, the size of the gap between the tone ring and the stator tends to fluctuate due to vibration or the like. As the air gap increases, the strength of the magnetic field and the output of the stator corresponding to the strength of the magnetic field decrease. The size of the gap varies randomly due to random factors. Variations in the size of the air gap adversely affect the measurement accuracy of the wheel speed sensor.

[0006] Modern automotive parts are required to be compact, lightweight, easy to assemble, and highly reliable. While traditional sensors are sufficient to meet these demands, engineers are working hard to develop sensors that are more compact, easier to manufacture and assemble, and lower cost. Further, such a sensor needs to be provided with some means for preventing mud, dust, salt, water and the like jumping from the road surface from entering the inside. Further, since such a sensor is provided near the brake, it is exposed to abrasion powder and high temperature due to the brake operation. Many recent wheel speed sensors are integrated into a wheel bearing device. This is because the sensor can be tested before the vehicle manufacturing process, the vehicle can be easily assembled, and the reliability of the entire device can be increased.

Therefore, there is a need for a wheel speed sensor capable of minimizing the fluctuation of the air gap between the rotor and the stator. It is also desirable that such sensors be easy to manufacture and low in cost. Further, such a sensor preferably has a structure that can be firmly fixed to the bearing by press fitting or the like. It is also desirable to take up as little installation space as possible.

[0008]

SUMMARY OF THE INVENTION The present invention provides an annular speed sensor that is capable of maintaining a high level of output even at relatively low wheel speeds, and is particularly suited as a vehicle wheel speed sensor. This wheel speed sensor is incorporated in the hub bearing device. The hub bearing device has sealing means for protecting the speed sensor.

One object of the present invention is to provide a wheel speed sensor capable of minimizing the fluctuation of the air gap between the rotor and the stator.

It is another object of the present invention to provide a wheel speed sensor that is easy to manufacture and has low manufacturing costs.

Still another object of the present invention is to provide a wheel speed sensor having a structure that can be firmly fixed to a bearing by press fitting or the like.

It is yet another object of the present invention to provide a wheel speed sensor that takes up little mounting space.

To achieve these objects, the present invention provides a multi-pole tone ring having an axial magnetic pole and a radial magnetic pole, and a first part for detecting the axial magnetic pole while the tone ring is rotating. And a stator having a second portion for detecting a magnetic pole in a radial direction. The sensor having this structure can accurately measure the wheel speed even when the wheel speed is relatively low because the fluctuation of the air gap between the rotor and the stator can be minimized. Also, even if the axial gap fluctuates, the possibility that the radial gap between the tone ring and the second portion of the stator fluctuates at the same time is low, so that accurate wheel speed measurement can be performed even in such a case. . Further, although a part of the gap between the magnetic pole of the tone ring and the plurality of first portions may fluctuate greatly, it is hardly considered that all of these gaps fluctuate simultaneously at the same time. Therefore, even if a part of the gap largely fluctuates, the whole gap substantially does not substantially change, and a wheel speed signal can be output with high accuracy.

The first and second portions of the stator are teeth formed on the stator. An axial magnetic field is detected by teeth facing the axial surface of the tone ring, and a radial magnetic field is detected by teeth facing the radial surface of the tone ring. With such a configuration, the influence of the variation in the air gap between the rotor and the stator on the sensitivity of the sensor can be minimized, so that the measurement accuracy can be further improved.

Further, since the stator of the present invention has an inner diameter portion or an outer diameter portion whose surface area is considerably larger than that of the conventional stator, the sensor is firmly fixed to the bearing or seal by press-fitting this portion into the bearing or seal. can do.

Further, as long as the teeth formed on the stator are arranged so as to be on the same line in the circumferential direction as the magnetic poles of the tone ring, strict accuracy in the circumferential direction is not required. Manufacturing cost can be reduced.

[0017]

1 and 2 show a hub bearing device 10 having an annular speed sensor according to the present invention. The hub bearing device 10 is normally mounted on a driven wheel axle of an automobile. However, the hub bearing device 10 can be mounted on a drive wheel axle or used on a rotating component other than an automobile component.

The hub 12 has a radial flange having a mounting surface to wheels (not shown). The hub 12 has a cylindrical inner peripheral surface 14 and a pair of roller bearing raceway surfaces, namely, an inboard raceway surface 16 and an outboard raceway surface 18. Further, the hub 12 has a large-diameter bore 20 for mounting a wheel rotation speed sensor described later.

A bearing inner ring 22 is provided inside the hub 12, and the inner ring 22 and a plurality of balls 24 rolling on the inner ring constitute an inboard bearing. The outboard-side bearing (not shown) is a conventional bearing provided with a plurality of balls rolling on the inner peripheral surface.
The inner ring 22 has a cylindrical inner peripheral surface 26 as a mounting surface for a fixed spindle 28. When the wheel rotates, the hub 12 fixed to the wheel rotates with respect to the inner ring 22 fixed to the spindle 28. The hub bearing device 10 of the present invention includes a sensor 30 for detecting the rotation speed of a wheel. As described above, the output of the sensor 30 is used for controlling the ABS and the traction control device of the vehicle. The sensor 30 includes a rotor or tone ring 32 and a stator or annular transducer. In addition to FIGS. 1 and 2, FIG.
The sensor 30 will be described with reference to 4, 5, 8, 9, and 10.

The tone ring 32 is a disk-shaped permanent magnet having a radial surface 36 and an axial inner peripheral surface 38. As shown in FIG. 2, the tone ring 32 is provided in the bore 20 of the hub.
Is attached to the tone ring holder 39 which is press-fitted. However, the holder 39 may be omitted and the tone ring 32 may be directly pressed into the bore 20 of the hub. The tone ring shown in FIGS. 4 and 9 has a plurality of regions extending radially from the center of rotation of the hub bearing device, and a magnetic pole opposite to the region adjacent to each region is formed. On the radial surface 36 and the axial surface 38, magnetic poles having opposite polarities are alternately formed in the circumferential direction.
An axial magnetic field 40 passes through the radial surface 36 and a radial magnetic field 42 passes through the axial surface 38. FIG. 4 shows the tone ring 3 when used in combination with the stator having first and second circumferentially offset teeth shown in FIG.
2 shows the magnetic field passing through FIG. FIG. 9 shows the magnetic field passing through the tone ring 32 when used in combination with the stator having first and second radially aligned teeth shown in FIG. There are various materials for the tone ring. In this embodiment, an Fe-Cr-Co alloy is used.

The annular transducer 34 has a case 44 consisting of a radial side wall 46 and a pair of cylindrical axial walls 48, 50 and having an open inner end. Wall 48,
50 are separated by an annular gap 52. Wall 4
A plurality of teeth 54, 56 are formed at the side ends of 8, 50. In the embodiment of FIG. 3, the teeth 54 are provided radially offset from the teeth 56, and in the embodiment of FIG.
4 are arranged on the same line in the radial direction with respect to the teeth 56. In FIG. 8, the bobbin 60 is omitted for easy understanding. As shown in FIGS. 1 and 3, a coil winding 58 wound around a bobbin 60 is housed in the gap 52. Tooth 5
The number of 4, 56 is equal to the number of magnetic poles alternately formed on the surface of the tone ring 32 in the circumferential direction.

When the tone ring 32 rotates (in the direction of the curved arrow A in FIGS. 3 and 8), the transducer teeth 5
4 and 56 are magnetically coupled to magnetic poles alternately formed in the tone ring, and an alternating magnetic field is generated in the case 44 of the transducer. Case 44 and tone ring 3 of FIG.
The arrows extending along the surface of No. 2 indicate the magnetic flux passing through the case 44 and the tone ring 32. Tone ring 3
When 2 rotates relative to the transducer, an alternating magnetic field is generated in the transducer case 44, resulting in an electromagnetic force (voltage) in the coil winding 58.
The magnetic poles 40, 42 and the teeth 54, 56 are provided such that the teeth 54 are magnetically coupled to the magnetic pole 40 and the teeth 56 are magnetically coupled to the magnetic pole 42. As shown in FIG. 3, the teeth 56 face the radially inner axial surface 38 of the tone ring 32 with a gap 55 therebetween. When the teeth 54 are magnetically coupled to one of the north and south poles,
Teeth 56 are arranged to couple to the other pole.
The tone ring 32 of FIG. 5 is used in combination with a transducer in which the teeth 54, 56 are circumferentially offset. In this case, when the teeth 54 are magnetically coupled to the N pole formed on the radial surface of the tone ring, the teeth 5 which are provided one pitch in the circumferential direction from the teeth 54 are provided.
Numeral 6 is magnetically coupled to the south pole of the axial plane, which is arranged one pitch in the circumferential direction from the north pole of the radial plane.
On the other hand, the tone ring 32 shown in FIG. 10 is used in combination with a transducer having radially aligned teeth 54 and 56. In this case, when the teeth 54 are magnetically coupled to the north pole formed on the radial surface, the teeth 56 arranged in a line in the radial direction with respect to the teeth 54 It is magnetically coupled to the south pole.

Since the tone ring of the present invention has a radial magnetic field on the axial surface and an axial magnetic field on the radial surface, the teeth 54 and 56 formed on the stator are respectively opposed to the opposite magnetic poles of the tone ring. What is necessary is just to be arrange | positioned so that it may oppose. The teeth 54, 56 may be circumferentially offset or radially aligned. Therefore tooth 5
4, 56 can be formed separately, and the manufacturing cost of the stator can be reduced.

The annular transducer 34 is press-fitted on the cylindrical outer peripheral surface of the inner race 22 shown in FIG. The bearing ball 24 and the sensor 30 are protected by a seal 62. The seal 62 includes a retaining ring 64 press-fitted to the hub 12 and the transducer case 4.
4 in contact with an elastic lip 66. The transducer is open at the inner end, i.e., the side facing the ball 24, and its walls 46, 48, 50 provide the ball 2 of the bearing.
4 are protected. Further, since the sensor 30 is mounted at a position easily accessible, repair and replacement can be easily performed.

FIGS. 6 and 7 show a hub bearing device 1 according to another embodiment.
Indicates 0 '. The hub bearing device 10 'has a sensor 30' for detecting the rotational speed of the wheel. Hub 12 '
Is provided with a radial flange portion 13 'having a mounting surface to a wheel (not shown). The wheel is fixed to the flange by a plurality of bolts 92 attached to the flange 13 '. The hub 12 'has a cylindrical inner peripheral surface 14'.
And a pair of roller bearing raceway surfaces, that is, an inboard raceway surface 16 'and an outboard raceway surface 18'. Further, a large-diameter bore 20 ′ for mounting a wheel rotation speed sensor is formed in the hub 12 ′.

A bearing inner ring 94 is provided inside the hub 12 ′, and the inner ring 94 and a plurality of balls 24 ′ rolling on the inner ring constitute an inboard bearing. When the wheels rotate, the inner ring 94 rotates with respect to the outer ring 96 fixed to a spindle (not shown). FIG.
As shown in the figure, the annular stator 98 of the sensor is
6, the tone ring 100 rotates together with the inner ring 94 fixed to the wheel.

FIGS. 11 and 12 show an embodiment in which the tone ring 110 and the annular transducer 112 are provided coaxially. The tone ring 110 is a ring-shaped member having a shaft 114 as a center. The annular transducer 112 is mounted radially inside the tone ring 110 about an axis 114 and includes an annular wall 120 and walls 116 and 118 extending radially outward from the annular wall 120. As in the other embodiments, the coil winding 12 wound on the bobbin 126
4 is a gap 12 inside the annular transducer 112.
2 The magnetic poles formed on the tone ring 110 and the teeth formed on the transducer may be provided on the same radial line or may be provided offset.

13 and 14, the tone ring 110 'and the annular transducer 112' are provided coaxially. The tone ring 110 'is a ring-shaped member centered on the shaft 114'. The annular transducer 112 'is centered on the axis 114' and the tone ring 11
0 ', radially outward, and an annular wall 120', and a wall 116 'extending radially inward from the annular wall 120',
118 '. As in the other embodiments, the bobbin 12
A coil winding 124 'wound on 6' is housed in a gap 122 'inside the annular transducer 112'. The magnetic poles formed on the tone ring 110 'and the teeth formed on the transducer may be provided on the same radial line or may be provided offset.

The present invention is not limited to the above embodiment, and various changes and improvements can be made to the above embodiment without departing from the scope of the claims.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a hub bearing device according to the present invention.

FIG. 2 is a partial longitudinal sectional view showing an assembled state of the hub bearing device of FIG. 1;

FIG. 3 is a diagram showing a part of an annular sensor in which a first tooth and a second tooth of a stator are formed so as to be circumferentially shifted.

FIG. 4 is a partially enlarged view of a tone ring of the present invention used in combination with a stator in which first teeth and second teeth are formed with circumferentially shifted first teeth.

FIG. 5 is a diagram showing magnetic poles in the radial direction of the tone ring of FIG. 4;

FIG. 6 is a longitudinal sectional view of a hub bearing device according to another embodiment of the present invention.

FIG. 7 is an enlarged view of a part of the sensor of FIG. 6;

FIG. 8 shows a portion of an annular sensor with first and second teeth of the stator radially aligned.

FIG. 9 is a partially enlarged view of the tone ring of the present invention used in combination with the stator of FIG. 8;

10 is a diagram showing magnetic poles in the radial direction of the tone ring of FIG. 9;

FIG. 11 is a perspective view of an embodiment in which a tone ring is provided on the outer periphery of the stator coaxially with the stator.

FIG. 12 is a sectional view taken along line 12-12 of FIG. 11;

FIG. 13 is a perspective view of an embodiment in which a tone ring is provided coaxially with the stator and inside the stator.

14 is a sectional view taken along the line 14-14 in FIG.

[Explanation of symbols]

30, 30 'wheel speed sensor 32, 100, 110, 110' tone ring (rotor) 34, 98, 112, 112 'transducer (stator) 44 case 54, 56 transducer teeth

Claims (18)

[Claims] 1. A circle having a plurality of axially arranged magnetic poles having opposite polarities and a plurality of radially arranged magnetic poles having opposite polarities alternately co-rotating with a rotating member. An annular stator comprising: a plate-shaped member; a first portion magnetically coupled to the axial magnetic pole; and a second portion magnetically coupled to the radial magnetic pole. Rotates
A magnetic flux is formed in the stator, and the magnetic flux generates an AC voltage representing the rotation speed of the disk member and the rotating member.The annular stator has a case made of a ferromagnetic material. An annular speed sensor for detecting a rotation speed of a rotating member, in which a conductive winding is accommodated in a case. 2. The first and second parts are teeth formed on the ferromagnetic case, and the teeth constituting the first part are axial magnetic poles having one of magnetism. 2. The sensor of claim 1, wherein the teeth comprising the second portion are magnetically coupled to radial poles of opposite magnetism when magnetically coupled to the magnetic pole. 3. The disk member has an axial surface and a radial surface, the radial magnetic pole is formed on the axial surface, and the axial magnetic pole is 3. The sensor according to claim 2, wherein teeth formed on a surface and constituting the second portion are provided across the radial surface and adjacent to the axial surface. 4. The case comprises a radial wall, an inner cylindrical wall and an outer cylindrical wall connected to the radial wall, and the teeth forming the first portion are formed on the inner cylindrical wall. The sensor according to claim 1, wherein the teeth forming the second portion are formed on the outer cylindrical wall. 5. The case comprises a radial wall, an inner cylindrical wall and an outer cylindrical wall connected to the radial wall, and the teeth forming the second portion are formed on the inner cylindrical wall. The sensor according to claim 1, wherein the teeth forming the first portion are formed on the outer cylindrical wall. 6. The disk member is mounted coaxially with the stator on the inner peripheral side of the stator, and the stator extends from the outer wall toward the disk member radially inward from the outer wall. The sensor according to claim 1, comprising two radial side walls, wherein teeth forming the first portion and the second portion are respectively formed on the two side walls. 7. The disk member is mounted coaxially with the stator on the outer peripheral side of the stator. The stator has a cylindrical inner wall, and extends radially outward from the inner wall toward the disk member. The sensor according to claim 1, comprising two radial side walls, wherein teeth forming the first portion and the second portion are respectively formed on the two side walls. 8. A bearing device comprising an outer race, an inner race inside the outer race, and a plurality of rolling elements provided between the inner and outer races so that the inner and outer races can rotate relative to each other. The sensor according to claim 1, wherein the sensor is fixed to one of the inner and outer rings, and the stator is fixed to the other of the inner and outer rings. 9. An outer ring, an inner ring inside the outer ring, a plurality of rolling elements provided between the inner and outer rings such that the inner and outer rings can rotate relative to each other, and a plurality of axial directions having opposite polarities alternately arranged. Magnetic poles, having a plurality of radially oriented magnetic poles having opposite polarities arranged alternately, a tone ring fixed to one of the inner and outer rings, and an annular transducer fixed to the other of the inner and outer rings. Wherein the transducer is formed of a ferromagnetic material having first teeth magnetically coupled to the axial magnetic poles and second teeth magnetically coupled to the radial magnetic poles. Wherein the axial and radial magnetic poles face the first and second teeth when the tone ring rotates relative to the transducer; In case made of magnetic material Contains a conductive winding, and when the tone ring rotates relative to the transducer, an alternating magnetic flux is generated in the transducer, and the magnetic flux generates an alternating voltage in the winding that indicates the speed of the relative rotation. Bearing device that is designed to produce 10. The bearing device according to claim 9, which is attached to a wheel. 11. The bearing device according to claim 10, wherein the inner ring is fixed to a non-rotating vehicle spindle, and the outer ring is fixed to the wheel. 12. The bearing device according to claim 11, wherein the tone ring is inserted into a cylindrical inner peripheral surface of an outer ring. 13. The bearing device according to claim 10, wherein the outer ring is fixed to a non-rotating vehicle spindle, and the inner ring is fixed to the wheel. 14. The bearing device according to claim 13, wherein the tone ring is inserted into a cylindrical outer peripheral surface of an inner ring. 15. The case comprises a radial wall, an inner cylindrical wall and an outer cylindrical wall connected to the radial wall, wherein the first teeth are formed on the inner cylindrical wall. , The second teeth are formed on the outer cylindrical wall,
The first and second teeth extend toward the rolling element, the tone ring is provided between the rolling element and the first tooth, and the second tooth is adjacent to the tone ring. The bearing device according to claim 9, wherein the bearing device is provided. 16. The bearing device according to claim 9, wherein a seal having a seal lip portion in contact with the transducer is fixed to a bearing outer ring to which the tone ring is attached. 17. The bearing device according to claim 9, wherein a seal having a seal lip portion that contacts the transducer is fixed to the bearing inner ring to which the tone ring is attached. 18. The bearing device according to claim 9, further comprising a seal having a seal lip surrounding the rolling element and the tone ring.