JPH10123158A - Rolling bearing unit with rotary speed detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve resolution while securing sensor output. SOLUTION: The number of protruding parts 38 provided at first and second stator elements 33 and 34 is made three fold the number of S or N pole being provided at a permanent magnet 22 that constitutes an encoder 20. Every time the encoder 20 rotates by the half pitch of the above protruding parts 38, the direction of the magnetic flux that flows in the first and second stator elements 33 and 34 changes, thus improving the resolution for detecting a rotary speed without increasing the number of S and N poles. Also, sensor output can be secured by increasing the distance between adjacent S and N poles and increasing the amount of magnetic flux that flows in the first and second stator elements 33 and 34.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The rolling bearing unit with a rotation speed detecting device according to the present invention is incorporated in a navigation system, an anti-lock brake system (ABS), or a traction control system (TCS) to rotate a wheel of a vehicle. Used to detect.

[0002]

2. Description of the Related Art In order to control an anti-lock brake system (ABS) or a traction control system (TCS) of a vehicle, it is necessary to detect a rotation speed of a wheel. Various types of rolling bearing units with a rotation speed detecting device for this purpose are known, for example, as described in US Pat. Nos. 5,2006,972, 5,231,391 and 5,438,260. FIG. 6 shows a rolling bearing unit with a rotation speed detecting device described in US Pat. No. 5,2006,976.

An encoder 1 including an annular permanent magnet is supported concentrically with a rotating wheel (not shown) and rotates with the rotating wheel. On the side surface of the encoder 1, S poles and N poles are alternately arranged at equal pitches in the circumferential direction. On the other hand, a sensor that is supported by a stationary wheel (not shown) concentrically with the rotating wheel and does not rotate includes a stator 2 made of a ferromagnetic material. Protrusions 3a, 3b are provided on both end edges of the stator 2, respectively.
And the notches 4a and 4b are alternately arranged in the circumferential direction, and at the same pitch as the S pole and the N pole (S
By providing them at a pitch of the combination of the poles and the N poles), the uneven edge portions 5a and 5b are formed. The phases of the two concavo-convex edges 5a and 5b in the circumferential direction are shifted from each other by a half pitch. Therefore, for example, one of the uneven edge portions 5a
At the moment when the protruding portions 3a and 3a confront the S pole, the protruding portions 3b and 3b forming the
Faces the N pole. As a result, an alternating magnetic flux flows through the stator 2 as the encoder 1 rotates.

[0004] A passive sensor is constructed by attaching a coil (not shown) to the stator 2. A voltage in the opposite direction is alternately induced in the coil in accordance with the alternating magnetic flux. The frequency at which this voltage changes is proportional to the rotation speed of the encoder 1. Therefore,
If the voltage induced in the coil is taken out as the output signal of the sensor and sent to the controller of the ABS or TCS, the ABS or TCS can be controlled. Note that the stator 2 is externally fitted and fixed to the end of the non-rotating inner race when assembled to the rolling bearing unit.

[0005]

In the case of the conventional structure constructed and operated as described above, it has been difficult to increase the resolution while securing the output of the sensor. The reason will be described with reference to FIG. In order to secure the output of the sensor, the protrusion 3a (3) provided on the stator 2 is provided in the magnetic flux flowing from the N pole to the S pole of the permanent magnet constituting the encoder 1.
b) must be present. On the other hand, the gap 6 between the tip of the protrusion 3a (3b) and the encoder 1
The thickness T of the (air gap) is a certain degree (for example, 0.5
(About 1 mm) or more. The reason for this is to prevent the tip of the protrusion 3a (3b) from rubbing against the encoder 1 irrespective of the dimensional error of the parts, the assembly error, and the elastic deformation accompanying the running of the automobile.

On the other hand, in order to improve the resolution of rotation speed detection, the S pole and N
It is necessary to increase the number of poles. In particular, when the output of the sensor is used for controlling a navigation system or TCS, it is necessary to accurately detect the rotation speed even when the vehicle is running at low speed. When the number of the S pole and the N pole is increased for such a purpose, the magnetic flux flowing from the N pole to the S pole of the permanent magnet is present only in the vicinity of the encoder 1. That is, as shown in FIG.
When the distance between the pole and the S pole is long, the magnetic flux flowing from the N pole to the S pole reaches a portion distant from the encoder 1. Therefore, even if the thickness T of the gap 6 is secured, a sufficient amount of magnetic flux flows through the protruding portions 3a (3b), and the output of the sensor can be secured. On the other hand, when the distance between the adjacent north pole and south pole is short as shown in FIG.
The magnetic flux flowing from the pole to the S pole does not reach the part distant from the encoder 1. Therefore, when the gap 6 is secured, a sufficient amount of magnetic flux does not flow through the protruding portions 3a (3b), and the output of the sensor cannot be secured. In view of such circumstances, the present invention has a structure in which a sufficient gap between the encoder and the sensor is secured to allow a sufficient magnetic flux to flow through the stator constituting the sensor, and sufficient detection of the rotational speed during low-speed running is performed. It is intended to realize a structure that can be performed with high accuracy.

[0007]

A rolling bearing unit with a rotation speed detecting device according to the present invention is provided with a rotating wheel and a rolling wheel, similarly to a conventionally known rolling bearing unit with a rotation speed detecting device.
The vehicle includes a stationary wheel, a plurality of rolling elements, an encoder, and a sensor. The rotating wheel has a rotating-side orbit on the rotating-side peripheral surface, and rotates during use. Further, the stationary wheel has a stationary-side track on the stationary-side peripheral surface opposite to the rotating-side peripheral surface, and does not rotate during use. In addition, the plurality of rolling elements are rotatably provided between the rotating-side track and the stationary-side track to allow rotation of the rotating wheel with respect to the stationary wheel. Further, the encoder includes an annular or disk-shaped permanent magnet in which S poles and N poles are alternately arranged at equal pitches in the circumferential direction, and a part of the rotating wheel is provided. , And is fixed concentrically with the rotating wheel. Further, the sensor is made of a ferromagnetic material such as iron and is arranged concentrically with the rotating wheel and the encoder, and has an annular or arc-shaped stator whose both end portions are opposed to the permanent magnet. And a coil for generating a voltage in response to a change in magnetic flux flowing in the stator. By providing a plurality of protrusions and notches at least on one edge of the stator alternately in the circumferential direction and at a pitch corresponding to the pitch of the S pole and the N pole provided on the encoder, An uneven edge is formed. Then, by alternately opposing the protruding portions constituting the concavo-convex edges to the S pole and the N pole, an alternating magnetic flux is caused to flow through the stator. In particular, in the rolling bearing unit with the rotation speed detecting device of the present invention, the number of the protruding portions constituting the concave and convex edge portions is determined by setting the number of S poles or N
The number of poles is an odd multiple that is three times or more.

Preferably, the concave and convex edge portions are provided at both end portions of the stator, and the circumferential phase of the projection and the notch constituting the concave and convex edge portions is set to the S pole. And in relation to the N pole. Then, at the moment when each protruding portion forming one concavo-convex edge faces the S pole or the N pole, each protruding portion composing the other concavo-convex edge is turned to the opposite pole (N pole or S pole). Make them face each other. More preferably, a non-magnetized portion is provided between adjacent S poles and N poles provided on the encoder, and the width of the non-magnetized portion is set to the width of the magnetized portions (S pole and N pole). Double or more.

[0009]

In the case of the rolling bearing unit with the rotation speed detecting device of the present invention configured as described above, when the permanent magnet forming the encoder rotates together with the rotating wheel, the uneven edge formed on the edge of the stator is formed. The magnetic poles facing the plurality of protrusions change alternately. Therefore, alternating magnetic flux flows in the stator as the rotating wheel rotates. As a result, the magnetic flux is less likely to be saturated in the stator. Then, an electromotive force is generated in the coil in accordance with the alternating magnetic flux flowing in the stator. In this way, an electromotive force is induced in the coil. The moment when a part of the protrusions forming the uneven edge faces the S-pole and the part of the protrusion forming the uneven edge becomes N As the flow direction of the magnetic flux is reversed at the moment when the magnetic flux is opposed to the pole, an electromotive force is alternately generated in the coil in the opposite direction. Therefore, the difference between the maximum value and the minimum value of the voltage can be made sufficiently large, and the reliability of the rotation speed detection can be improved.

[0010] In particular, in the case of the rolling bearing unit with the rotation speed detecting device of the present invention, the number of the protruding portions constituting the concave and convex edge portions is set to the number of the S pole or the N pole provided on the encoder, respectively. Therefore, since the number is set to an odd number of 3 times or more, the amount of magnetic flux flowing in the stator through each of the projecting portions can be ensured, and the accuracy of rotation speed detection at low speed can be improved.

[0011]

1 to 3 show an embodiment of the present invention. In this example, the non-drive wheels (front wheels of FR vehicles,
Rolling bearing unit to support the rear wheels of FF vehicles)
This is an application of the present invention. On the inner peripheral surface of the stationary wheel 7 that is the stationary peripheral surface, double rows of outer ring raceways 8 and 8 that are stationary stationary raceways are formed. The fixed wheel 7 can be supported on a suspension device by a flange 9 formed on the outer peripheral surface thereof. A rotating wheel 10 is arranged inside the fixed wheel 7. Inner ring raceways 11, 11, each of which is a rotating side track, are provided on the outer circumferential surface of the rotating ring 10, which is a rotating side circumferential surface.
And these two inner raceways 11 are opposed to the outer raceways 8. And the outer ring raceway 8,
8 and the inner ring raceways 11, 11, respectively.
A plurality of rolling elements 13 held rotatably by 2 and 12;
13 is provided, and the rotating wheel 10 is rotatably supported inside the fixed wheel 7.

In the illustrated example, balls are shown as rolling elements. However, in the case of a heavy-duty rolling bearing unit for an automobile, tapered rollers may be used as rolling elements. A flange 14 for fixing a wheel to the rotating wheel 10 is provided in a portion near the outer end of the outer peripheral surface of the rotating wheel 10 and protruding from an outer end opening of the fixed wheel 7. Also, between the outer peripheral surface of the rotating wheel 10 (the outer lateral end of the vehicle in the assembled state to the vehicle and the left end in FIG. 1) and the outer peripheral surface of the fixed wheel 7 Is fitted with a seal ring 15 to close the outer end opening of the space 16 where the rolling elements 13 and 13 are installed. In the case of the present example, the rotating wheel 10 is configured by externally fitting the inner ring 18 to the outer peripheral surface of the inner end portion of the hub 17. That is, while the inner ring 18 is externally fitted, a nut 41 is screwed and fastened to the male screw portion 19 formed at the inner end of the hub 17, and the inner ring 18 is fixed to the hub 17. Is composed.

On the other hand, the inner end of the rotating wheel 10 (the end in the width direction center side of the vehicle when assembled to the vehicle,
On the outer peripheral surface (right end in FIG. 1), the whole was formed in an annular shape.
The encoder 20 is externally fitted and fixed. This encoder 2
Reference numeral 0 denotes a support ring 21 formed into a cylindrical shape by press-forming a metal plate, and a permanent magnet 22 supported and fixed to a part of the support ring 21. Of these, the support ring 21
A cylindrical portion 23 and an axially outer edge of the cylindrical portion 23 (FIGS. 1 to 1)
2 from the left edge of the circle 2)
4 is provided. A fitting tube portion 25 is formed by folding the metal plate 180 degrees at an intermediate portion in the diametrical direction on the outer surface (left side surface in FIGS. 1 and 2) of the circular ring portion 24. The fitting cylindrical portion 25 is concentric with the cylindrical portion 23, and has an inner diameter in a free state slightly smaller than the outer diameter of the inner end of the inner ring 18. Accordingly, the support ring 21 can be freely fixed to the inner end of the rotating wheel 10 by fitting the fitting cylindrical portion 25 to the inner end of the inner ring 18 by interference fit.
Further, the cylindrical portion 2 of the support ring 21 is fixed in this manner.
3 is concentric with the rotating wheel 10.

In the above-described support ring 21, the cylindrical portion 2
The permanent magnet 22 is attached to the inner peripheral surface of the third magnet 3. This permanent magnet 22 which is a rubber magnet or a plastic magnet
S poles and N poles are arranged alternately in the circumferential direction and at the same pitch on the inner peripheral surface of. In the case of this example, the permanent magnet 22 has a sufficiently large interval between the S pole and the N pole adjacent in the circumferential direction, so that the magnetic flux coming out of the N pole and entering the S pole is formed in the permanent magnet 22. It is designed to reach the diametrically inner side sufficiently from the peripheral surface. Further, a non-magnetized region is provided in a portion between the S pole and the N pole which are adjacent in the circumferential direction to reduce the magnetic flux flowing directly from the N pole which is adjacent in the circumferential direction to the S pole. Is secured in the amount of magnetic flux flowing in the stator 27. In the case of this example, since the interval between the S pole and the N pole adjacent in the circumferential direction is sufficiently widened, the width of the non-magnetized region is set to the magnetized portion (S pole and N pole).
The magnetic flux flowing directly from the north pole to the south pole adjacent to each other in the circumferential direction can be sufficiently reduced.

In the present invention, by devising the structure of the sensor 26 in relation to the magnetization pitch of the permanent magnet 22,
Even if the magnetization pitch is not made very small, the accuracy of rotation speed detection is improved. In the case of the illustrated example, the S pole and the N pole are connected to the permanent magnet 22 for simplicity.
Are arranged at two places on the inner peripheral surface, respectively, for a total of four places. However, in the actual case, even if the number of the S poles and the N poles is increased, the magnetic flux coming out of the N pole and entering the S pole is sufficiently diametrically inner than the inner peripheral surface of the permanent magnet 22. To reach.

At the inner end opening (the right end opening in FIG. 1) of the fixed ring 7, an outer end opening of a bottomed cylindrical cover 28 formed by injection molding of a synthetic resin is fixed. This fixed wheel 7
The inner end opening is closed. The sensor 26 is embedded in the synthetic resin forming the cover 28. With the cover 28 fitted and fixed to the inner end opening of the fixed wheel 7, the outer peripheral surface of the sensor 26 is
0 faces the inner peripheral surface of the permanent magnet 22 via the gap 6. In addition, at the outer end opening of the cover 28,
By embedding a sleeve 29 having an L-shaped cross section and being formed in an annular shape as a whole, and fitting the sleeve 29 into an inner end opening of the fixed ring 7, the cover 2 for the fixed ring 7 is formed.
8 is maintained. In addition, an O-ring 30 is provided between the outer peripheral surface of the outer end opening of the cover 28 and the inner peripheral surface of the inner end opening of the fixed wheel 7 to ensure the sealing performance between these two peripheral surfaces. I have.

The sensor 26 includes an annular stator 27 made of a ferromagnetic material such as a mild steel plate and a U-shaped cross section, and an annular bobbin 31 made of a nonmagnetic material such as a synthetic resin.
And a coil 32 formed by winding a conductive wire.
The stator 27 is formed by combining the first stator element 33 and the second stator element 34. By forming protrusions and notches alternately and at equal intervals on the outer peripheral edges of these first and second stator elements 33 and 34, respectively, the first and second uneven edge portions 35 are formed. , 3
6 are formed. The pitches (center angle pitches) of the notches 37, 37 and the projections 38, 38 forming the two concave and convex edge portions 35, 36 are equal to each other.

The pitch of the notches 37, 37 and the projections 38, 38 is regulated by the relationship with the pitch of the S pole and the N pole disposed on the inner peripheral surface of the permanent magnet 22 constituting the encoder 20. doing. That is, the above-mentioned concave and convex edge portions 3
Protrusions 38, 38 and notches 3 constituting 5, 36
The numbers 7 and 37 are odd times (3, 3 times or more) with respect to the number of S poles or N poles provided in the encoder 20, respectively.
5, 7, 9, ... times. 3 times in the example shown. ). The number of protrusions 38, 38 and notches 37, 37
The higher the number, the higher the resolution. However, if the number increases, the facing area between the S and N poles and the respective protrusions 38, 38 decreases, and the amount of magnetic flux flowing in the stator 27 decreases.
When the amount of magnetic flux decreases, the voltage induced in the coil 32 constituting the sensor 26 decreases, and it becomes difficult to ensure detection accuracy. Therefore, the projections 38, 38 and the notches 37, 3
The number 7 is regulated to 3 or 5 times, more preferably 3 times the number of S poles or N poles.

The phase of the first uneven edge 35 formed on the outer peripheral edge of the first stator element 33 and the second uneven edge formed on the outer peripheral edge of the second stator element 34 The phases of the notches 37 and 37 and the projection 3
The pitches are shifted by half of the pitches 8 and 38 (the pitch between the adjacent notch 37 and the protruding portion 38). Therefore, at the moment when a part of the plurality of protrusions 38 constituting the first concave / convex edge 35 faces the S pole disposed on the inner peripheral surface of the permanent magnet 22, Second uneven edge 36
A part of the plurality of protrusions 38 constituting
Faces the N pole. Further, from this moment, at the moment when the encoder 20 is rotated by half the pitch of the notches 37, 37 and the protrusions 38, 38, the plurality of protrusions 38 forming the first concave / convex edge 35 are formed. Some of the protrusions 38 face the N pole disposed on the inner peripheral surface of the permanent magnet 22, and some of the protrusions 38 forming the second concave / convex edge 36. The portion 38 faces the south pole.

The first and second stator elements 33,
The inner peripheral edges of the second stator element 34 are tightly fitted to the first cylindrical section formed on the inner peripheral edge of the first stator element 33. Magnetic conduction is achieved by fitting inside. Accordingly, alternating magnetic flux flows in the first and second stator elements 33 and 34 as the encoder 20 rotates. still,
The second cylindrical portion is displaced axially inward from the maximum diameter portion of the nut 41 to prevent interference with the nut 41 and to effectively use a limited space. or,
The coil 32 is configured by winding a conductive wire around a bobbin 31 having an open outer peripheral side. In addition, this bobbin 31
An uneven engagement portion is provided between the first and second stator elements 33 and 34, and the phase of the first and second stator elements 33 and 34 is set via the bobbin 31 as described above. Regulations. An AC voltage is induced in the coil 32 formed by winding a wire around such a bobbin 31 in accordance with the alternating magnetic flux. Such an AC voltage can be taken out via a connector 39 formed integrally with the cover 28 on a part of the inner surface of the cover 28. This AC voltage is sent to the controller as a signal indicating the rotation speed of the hub 1 and used for controlling the ABS, TCS, or navigation system.

In the case of the rolling bearing unit with the rotation speed detecting device according to the present invention configured as described above, both ends of the stator 27 are formed with the rotation of the rotating wheel 10 to which the wheel is fixed.
Some of the plurality of protrusions 38, 38 constituting the concave and convex edge portions 35, 36 formed on the outer peripheral edges of the first and second stator elements 33, 34, respectively,
The magnetic poles (S pole, N pole) facing each other alternately change. Moreover, the magnetic poles facing the respective projecting portions 38, 38 constituting the both concave and convex edge portions 35, 36 are opposite to each other. As a result, an alternating magnetic flux flows in the stator 27.

The mechanism in which the alternating magnetic flux flows in the stator 27 will be described with reference to FIG.
In the case of an actual rotation speed detecting device, the stator 27
Is fixed, and the permanent magnets 22 constituting the encoder 20 are fixed.
3A to 3C, the circumferential position of the stator 27 is changed without changing the circumferential position of the encoder 20 for convenience of explanation. At a certain moment, as shown in FIGS. 3A and 3A, a plurality of protrusions 38, 38 forming a first uneven edge 35 formed on the outer peripheral edge of the first stator element 33. Part of the protruding portions 38, 38 shown by solid lines in FIG.
The projections 38, 38 of 3) oppose the N pole, and the second uneven edge 35 formed on the outer peripheral edge of the second stator element 34.
Of the plurality of projections 38, 38 {the projections 38, 38} shown by broken lines in FIG. Opposite the pole.
At this moment, a magnetic flux flows from the outer peripheral edge of the first stator element 33 toward the outer peripheral edge of the second stator element 34.

On the other hand, from the state shown in FIG. 3A and FIG. 3A, the encoder 20 moves the notches 37 and 37 and the projections forming the first and second concave and convex edge portions 35 and 36. At the moment of rotation by half pitch of 38, 38, FIG.
(A) As shown in (b), a part of the plurality of protrusions 38, 38 constituting the uneven edge 35 formed on the outer peripheral edge of the first stator element 33, 38, 38. Are opposed to the south pole, and some of the projections 38, 38 of the plurality of projections 38, 38 forming the uneven edge 35 formed on the outer peripheral edge of the second stator element 34 are located on the north pole. opposite. At this moment, a magnetic flux flows from the outer peripheral edge of the second stator element 34 toward the outer peripheral edge of the first stator element 33.

Further, the encoder 20 is moved from the state shown in FIGS.
Notches 37, 37 and projecting portions 3 constituting 5, 36
At the moment of rotation by half pitch of 8, 38, FIG.
As shown in FIGS. 3A and 3C, similarly to the state shown in FIGS. 3A and 3A, a plurality of first concave and convex edge portions 35 formed on the outer peripheral edge portion of the first stator element 33 are formed. Some of the protrusions 38, 38 of the protrusions 38, 38 face the N-pole, and a plurality of protrusions forming a second uneven edge 36 formed on the outer peripheral edge of the second stator element 34. Some protruding portions 38 of the portions 38 face the south pole. At this moment, a magnetic flux flows from the outer peripheral edge of the first stator element 33 toward the outer peripheral edge of the second stator element 34.

Therefore, an alternating magnetic flux flows in the stator 27 with the rotation of the rotating wheel 10 to which the encoder 20 is fixed. Therefore, the magnetic flux is less likely to be saturated in the stator 27. Then, an electromotive force is generated in the coil 32 according to the alternating magnetic flux flowing in the stator 27 in this manner. The electromotive force is induced in the coil 32 in this manner. For example, a part of the protrusion 3 forming the first uneven edge 35 formed on the outer peripheral edge of the first stator element 33 is formed.
With the fact that the flow direction of the magnetic flux is reversed between the moment when the first and second electrodes 8 and 38 face the north pole and the moment when a part of the projections constituting the first concave / convex edge 35 faces the south pole, Coil 32
, An electromotive force in the opposite direction is generated alternately. For this reason, the difference between the maximum value and the minimum value of the voltage can be made sufficiently large, and the accuracy of rotation speed detection can be improved.

The period from the moment shown in FIGS. 3A and 3A to the moment shown in FIGS. 3A and 3C constitute one cycle of the AC voltage induced in the coil 32. In order to increase the resolution of the rotation speed detection device, it is necessary to increase the number (cycle number) at which the AC voltage changes while the encoder 20 makes one rotation. As in the illustrated example, the protrusions 38, 38
If the number of notches 37, 37 is three times the number of S poles or N poles, the number of cycles is increased even if the interval between the S poles and N poles adjacent in the circumferential direction is widened. , The resolution can be increased. That is, FIGS.
As can be seen from (c), even if the magnetization pitch of the encoder 20 is set to 180 degrees, the cycle at which the AC voltage changes is only 60 degrees. Accordingly, a resolution three times the magnetization pitch can be obtained.

On the other hand, FIG. 3B (a) to (c)
As shown in the figure, the protrusions 38, 38 and the notches 37, 37
Is the same as the number of S poles or N poles, the cycle in which the AC voltage changes is the same as the cycle of these S poles and N poles. Therefore, in the case of FIG. 3B, the cycle at which the AC voltage changes is 180 degrees. In other words, the protrusion 3
When the number of the notches 8, 38 and the notches 37, 37 is the same as the number of the S pole or the N pole, it is necessary to increase the number of the S pole and the N pole in order to increase the resolution. Figure 7 of
As shown in (B), it becomes difficult for the magnetic flux to reach a portion distant from the permanent magnet 22, and it becomes difficult to secure the output of the sensor 26.

The shape and the magnetization method of the permanent magnet 22 constituting the encoder 20 are not particularly limited. For example, the permanent magnet 22 shown in FIG. 4 is attached to the permanent magnet 22 by a magnetizing device 40 shown in FIG. If magnetized, the above-described encoder 20 can be manufactured efficiently. That is, the permanent magnet 22 which is a rubber magnet or a plastic magnet is molded on the inner peripheral surface of the cylindrical portion 23 constituting the support ring 21. The permanent magnet 22 has an even number of wide magnetized portions 42 at equal circumferential intervals. Further, the magnetized portions 42, 42 adjacent in the circumferential direction are non-magnetized portions 43, 43 having a narrow width.
The molding of the magnetized portions 42 and 42 and the non-magnetized portions 43 and 43 can be performed all at once.

On the other hand, the magnetizing device 40 forms an even number of protrusions 45 on the outer peripheral surface of the yoke 44 made of a ferromagnetic material at regular intervals with the magnetized portions 42, 42. A magnetizing coil 46 is wound around the parts 45, 45. When magnetizing the permanent magnet 22, each of the protrusions 45,
45, the outer peripheral end faces of the magnetized portions 42, 42,
The magnetizing coil 46 is energized. Each of the protrusions 45, 4
The width and length of the outer peripheral end face of the respective magnetized portions 42, 42
Since the entire body is regulated so as to be magnetized, the entire inner peripheral surface of each magnetized part 42 can be magnetized to the S pole or the N pole with the energization.

The first and second concave / convex edge portions 35, 3
Reference numeral 6 designates the widthwise ends of the respective magnetized portions 42, 42 so as to oppose only the portions protruding from the side edges of the non-magnetized portion 43. The reason for such a configuration is as follows.
Usually, the boundary between the magnetized part and the non-magnetized part is not clear,
As the widths of the magnetized portions 42, 42 are increased, the portions adjacent to the magnetized portions 42, 42 at the circumferential ends of the non-magnetized portions 43, 43 are slightly attached. Even if it is magnetized, the change in the magnetic flux density flowing in the first and second stator elements 33 and 34 increases. That is, the first and second concavo-convex edge portions 35 and 36, which are the peripheral portions of the first and second stator elements 33 and 34, are located at the widthwise ends of the magnetized portions 42 and 42, respectively. The first and second concave / convex edge portions 3 are opposed only to portions protruding from the side edges of the magnetized portion 43.
Reference numerals 5 and 36 alternately face the magnetized portions 42 and 42 of the permanent magnet 22 constituting the encoder 20 and portions where the permanent magnet 22 is not provided. For this reason, the boundary between the magnetized portions 42, 42 and other portions becomes clear, and the change in the density of the magnetic flux passing through the first and second stators 33, 34 increases with the rotation of the encoder 20. As a result, the output voltage induced in the coil 32 increases.

In order to increase the density change of the magnetic flux passing through the first and second stators 33 and 34 for the above purpose, the inner diameters of the magnetized portion and the non-magnetized portion are made different. But you can. That is, instead of making the widths of the magnetized portion and the non-magnetized portion the same, the thickness of the permanent magnet constituting the encoder is increased in the magnetized portion and reduced in the non-magnetized portion, and the inner diameter of the magnetized portion is reduced. Is smaller than the inner diameter of the non-magnetized portion. If you do this,
The gap between the first and second stators 33 and 34 and the inner peripheral surface of the permanent magnet is small in the magnetized portion and large in the non-magnetized portion. As a result, even if the circumferential edge of the non-magnetized portion is somewhat magnetized, the encoder rotates,
From the non-magnetized portion, the first and second stators 33, 34
The magnetic flux flowing through the first and second stators 33 and 34 is increased as in the case of the illustrated example, and the output voltage induced in the coil 32 is increased. it can.

In the illustrated example, the sensor 26 is disposed on the inner diameter side of the encoder 20. However, the sensor may be disposed on the outer diameter side of the encoder, or the sensor and the encoder may extend in the axial direction. It is also possible to face each other. In short,
The arrangement state of the sensor and the encoder is designed in accordance with the structure of the rolling bearing unit in which the rotation speed detecting device is to be incorporated. In addition, if the uneven edge portions are formed at both end portions of the stator so as to be shifted from each other by a half pitch, the amount of change in the magnetic flux flowing through the stator can be increased, and the output of the sensor can be increased. However, if at least one of the edge portions is provided on the concave and convex edge, it is possible to exert a tentative function. In this case, the other edge is a straight edge, for example, in a portion other than the permanent magnet constituting the encoder, such as a part of a rotating wheel made of a ferromagnetic material, in a portion which is magnetically conductive with the permanent magnet. Make them face each other.

[0033]

Since the present invention is constructed and operates as described above, a rolling bearing unit with a rotation speed detecting device having a large output and a high resolution can be realized.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a first example of an embodiment of the present invention.

FIG. 2 is an enlarged view of the right part of FIG.

3A and 3B are schematic front views showing a mechanism in which alternating magnetic flux flows through a stator, wherein FIG. 3A shows a case of the structure of the present invention, and FIG. 3B shows a case of a conventional structure.

FIG. 4 is a cross-sectional view showing an example of an encoder used for implementing the present invention.

FIG. 5 is a schematic front view of a magnetizing device.

FIG. 6 is a partially cut perspective view showing one example of a conventional structure.

FIG. 7 is a schematic diagram for explaining an effect of a magnetized pitch on an output of a sensor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Encoder 2 Stator 3a, 3b Projection 4a, 4b Notch 5a, 5b Irregular edge 6 Gap 7 Fixed ring 8 Outer ring raceway 9 Flange 10 Rotating ring 11 Inner ring raceway 12 Cage 13 Rolling member 14 Flange 15 Seal ring 16 Space 17 Hub 18 Inner Ring 19 Male Thread 20 Encoder 21 Support Ring 22 Permanent Magnet 23 Cylindrical Part 24 Circular Ring 25 Fitting Tube 26 Sensor 27 Stator 28 Cover 29 Sleeve 30 O-ring 31 Bobbin 32 Coil 33 First Stator Element 34 Second Stator element 35 First uneven edge 36 Second uneven edge 37 Notch 38 Projection 39 Connector 40 Magnetizer 41 Nut 42 Magnetizer 43 Non-magnetizer 44 Yoke 45 Projector 46 Magnetizing coil

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI G01D 5/245 G01D 5/245 V

Claims (1)

[Claims] 1. A stationary wheel having a rotating raceway on a rotating peripheral surface and rotating during use, and a stationary raceway having a stationary raceway on a stationary peripheral surface opposite to the rotating peripheral surface during use. A wheel, a plurality of rolling elements rotatably provided between the rotating-side track and the stationary-side track, and S poles and N poles arranged alternately and at equal pitch in the circumferential direction. It is configured to include a ring-shaped or disk-shaped permanent magnet, and part of the rotating wheel,
An encoder supported and fixed concentrically with the rotating wheel, and a sensor supported by the stationary wheel and opposed to a permanent magnet constituting the encoder, the sensor is made of a ferromagnetic material, and includes the rotating wheel and the encoder. An annular or arc-shaped stator concentrically arranged and having both ends facing the permanent magnet, and a coil attached to the stator and generating a voltage in response to a change in magnetic flux flowing through the stator; A plurality of protrusions and notches are respectively provided at least at one edge of the stator, the pitches corresponding to the pitches of the S pole and the N pole provided in the encoder alternately in the circumferential direction. By forming the uneven edge portion by providing the protrusions, the protrusions constituting the uneven edge portion are alternately opposed to the S pole and the N pole, so that the stator has an alternating magnetic field. In the rolling bearing unit with the rotation speed detecting device for flowing the fluid, the number of the projecting portions constituting the concave and convex edge portions is an odd number which is three times or more as large as the number of S poles or N poles provided in the encoder, respectively. A rolling bearing unit with a rotation speed detection device, characterized in that it is doubled.