JP2008224440A - Bearing rotation detecting apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bearing rotation detecting apparatus capable of significantly increasing the resolution of angle detection without increasing the number of magnetic poles. <P>SOLUTION: This bearing rotation detecting apparatus has a plurality of magnetic field detecting elements 51 and 52 arranged at mutually different angular positions in the circumferential direction of a pulsar ring 11, in the relation where phase difference smaller than 1/2-wavelength of a periodic waveform is generated between detection waveforms with respect to the same pulsar ring 11. Then, the detection waveform of each of the magnetic field detecting elements 51 and 52 is converted into a square waveform, the start-up edges and falling edges of the waveform are counted as angular information in the coming order in the mutually mixing form without distinguishing which element the edges belong to the detection wave form of. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a bearing rotation detection device.

JP 2004-198378 A JP 2000-249138 A JP 2002-40037 A

  Optical rotary encoders are widely used as rotation sensors, but magnetic rotation sensors are often used for detecting rotation of automobile undercarriage systems in order to prevent erroneous detection due to dirt adhesion and the like. . There are various types of magnetic rotation sensors. Magnetic field detection elements such as magnetic heads, magnetoresistive effect elements, or Hall elements are arranged through magnetic gaps on a magnetic object that rotates together with the object to be detected. A method of measuring the magnetic field fluctuation in the magnetic gap based on the rotation of the object to be detected and calculating the rotation angle using the detected waveform is widely used because the sensor structure is relatively simple and accurate.

  In recent years, in order to use the magnetic rotation sensor as described above for control of an anti-lock brake system (ABS) or the like, a rolling bearing in which a magnetic sensing element ring (for example, a pulsar ring) of the sensor is attached as a rolling bearing for supporting an axle. A bearing is employed (for example, Patent Documents 1 to 3). In this type of rolling bearing, a structure in which a pulsar ring is attached to an inner ring to which an axle that is a rotation detection target is attached, and a detection unit including a magnetic field detection element is attached to the non-rotating outer ring side.

  In recent years, in order to improve the control response of ABS, there has been a demand for higher detection accuracy of wheel lock / rotation, and a rotation sensor attached to a hub unit also needs to improve resolution of angle detection. In order to improve the resolution of the magnetic rotation sensor, it is necessary to further increase the number of magnetic poles of the pulsar ring. However, if the number of magnetized poles is increased unnecessarily, the width of each magnetized region becomes too small, the magnetic flux decreases, and the effect of demagnetization due to close proximity increases, so the magnetic field strength required for sensing is reduced. There is a problem that cannot be obtained.

  An object of the present invention is to provide a bearing rotation detection device that can greatly increase the resolution of angle detection without increasing the number of magnetic poles.

Means for Solving the Problems and Effects of the Invention

In order to solve the above problems, the bearing rotation detection device of the present invention is
A bearing having an inner ring, an outer ring disposed concentrically on the outer side of the inner ring, and a plurality of rolling elements disposed between the inner ring and the outer ring;
A pulsar ring that is configured as a permanent magnet member concentrically fixed to one of the inner ring and the outer ring, and in which first and second magnetized regions having different magnetic polarities are alternately formed at equal intervals;
The magnetic field fluctuations formed by the first and second magnetized regions that are arranged opposite to each other in a non-rotating manner so as to form a magnetic gap with respect to the pulsar ring and pass alternately with the rotation of the pulsar ring are adjacent to each other. Each pair of the first and second magnetized regions to be detected is detected as a periodic waveform formed repeatedly, and a phase difference smaller than ½ wavelength of the periodic waveform is generated between the detected waveforms. In relation, a plurality of magnetic field detection elements arranged at different angular positions in the circumferential direction of the pulsar ring,
A waveform shaping unit that squares the detection waveform of each magnetic field detection element;
The counting signals corresponding to the rising and falling edges of the plurality of detection waveforms that are square-shaped are output in the order of arrival in a mixed form in time series without distinguishing which detection waveform belongs to And an edge count signal output means.

  According to the above configuration, for the same pulsar ring, they are arranged at different angular positions in the circumferential direction of the pulsar ring in a relationship that causes a phase difference smaller than ½ wavelength of the periodic waveform between detection waveforms. A plurality of magnetic field detection elements are provided. Then, the detection waveform of each magnetic field detection element is squared, and the rising edge and falling edge of the waveform are mixed with each other in time series without distinguishing which element the detection waveform belongs to. Count as angle information in the order of arrival. Thereby, even if the number of magnetized regions (number of magnetized poles) of the pulsar ring is the same, the arrival intervals of the waveform rising edge and the falling edge representing the detection angle interval are increased by the increase in the number of magnetic field detection elements. The angle detection resolution can be greatly increased.

  Each of the plurality of magnetic field detection elements can be constituted by a Hall element. The Hall element is a small and highly sensitive magnetoelectric conversion element, which is convenient for incorporation into a bearing as a detection element.

  The plurality of magnetic field detection elements are arranged in the circumferential direction of the pulsar ring so that the rising edge and the falling edge of each square-shaped detection waveform are equally divided into one wavelength section of each detection waveform. It is desirable to arrange them at different angular positions. In this way, the arrival angle intervals of the rising and falling edges of the detection waveforms output one after another from the plurality of magnetic field detecting elements become uniform, and the calculation for obtaining the actual angular position or rotational speed from the edge count value Processing is greatly simplified. Geometrically, when the number of arranged magnetic field detection elements is n, the magnetic field detection elements are arranged such that the phases of the detection waveforms are sequentially shifted by (1 / 2n) wavelengths. Thus, the above configuration can be realized. For example, when the number of magnetic field detection elements to be arranged is 2, these magnetic field detection elements are preferably arranged so that the phase of each detection waveform is in a positional relationship shifted by (1/4) wavelength.

  The pulsar ring magnetized region is arranged with an angular span of ½ wavelength or less because the pair of the first magnetized region and the second magnetized region adjacent to each other corresponds to the rotation angle range for one wavelength of the detection waveform. The plurality of magnetic field detecting elements can be arranged adjacent to each other so as to be within one magnetized region. In this case, the magnetic field detection elements arranged adjacent to each other can be integrated by a common resin mold to form a detection module. In this way, a plurality of magnetic field detection elements can be collectively assembled to the bearing in the form of a detection module, the assembly process can be simplified, and the apparatus can be miniaturized. In particular, when a magnetoelectric conversion element is employed as the magnetic field detection element, a signal processing circuit (which can be constituted by an IC) of the element output can be incorporated into the resin mold, and further miniaturization can be achieved. In this configuration, it is advantageous to employ a relatively small magnetoelectric conversion element such as the Hall element described above.

  On the other hand, a plurality of magnetic field detection elements can obtain an equivalent detection waveform without necessarily being arranged adjacent to each other by using the periodicity of the magnetized region on the pulsar ring, and the periodicity of the detection waveform formed thereby. Can do. Specifically, it can be dispersedly arranged in the circumferential direction of the pulsar ring at an angular interval wider than the angular interval between the first and second magnetized regions adjacent to each other. In this way, even when it is difficult to place the magnetic field detection elements adjacent to each other in space, it can be handled without any problem, and the degree of design freedom related to the element layout can be greatly increased. Further, it is advantageous in increasing the number of magnetic field detection elements arranged, and contributes to further improvement in angle detection resolution.

  The bearing has a hub wheel in which an outer ring is mounted non-rotatably on the vehicle body side, is concentrically arranged with the outer ring, and a wheel mounting flange is formed in a circumferential direction. The inner ring is at least a vehicle inner side end of the hub wheel. Further, it can be configured as a vehicle hub unit that includes a rolling element row that is fitted to the outer peripheral surface of the portion and is arranged in the circumferential direction between the inner ring or the hub wheel and the outer ring. As a result, the bearing rotation detection device of the present invention can be applied to ABS control, traction control, etc. for vehicles (particularly for automobiles). For example, when applied to ABS control, detection of lock / rotation of wheels. The accuracy can be greatly increased.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing a hub unit 1 which is an example of a bearing to which the present invention is applied. In both figures, the left side is the vehicle outer side, and the right side is the vehicle inner side. As shown in FIG. 1, the hub unit 1 includes an outer ring 2 as a fixed ring having two rows of tracks, a hub shaft (hub wheel) 3 arranged concentrically with the outer ring 2, and a rotating wheel having a row of tracks. The inner ring 4, double row rolling element rows 5, 5, and crown-shaped cages 153, 153 are provided, and the large-diameter outer peripheral surface 3 b of the hub shaft 3 has a row of tracks.

  The outer ring 2 is a hot forged material of carbon steel for machine structure such as S55C, and has a cylindrical outer ring main body (main body) 20 having two rows of raceway surfaces on the inner periphery, and an outer periphery of the outer ring main body 20. And an outer ring flange portion 23 protruding in the radial direction from the surface. A portion of the main body portion 20 that protrudes further toward the vehicle inner side than the outer ring flange portion 23 is an outer ring inlay portion 21 that forms an attachment portion to the vehicle body. The outer ring flange portion 23 is formed with a bolt insertion hole 23h in the axial direction.

  Positioning with respect to the bolt insertion hole formed on the vehicle body side is performed by the outer peripheral surface 21a on the vehicle inner side of the outer ring inlay part 21, and the bolt 26 is inserted into the bolt insertion holes 81h, 82h, and 23h, thereby the outer ring flange of the outer ring 2 A vehicle body side carrier (knuckle) 82 is fixed to the vehicle inner side main surface 23a of the portion 23 with a spacer 81 interposed therebetween. Thereby, the hub unit 1 is fixed to the vehicle body. A tire wheel (wheel) 6 is rotatably supported with respect to the vehicle body via the outer ring 2. A protective cap (cap portion) is attached to the vehicle inner side end opening 21h of the outer ring 2 so as to be able to rotate integrally with the outer ring 2 so as to cover the opening 21h.

  The hub shaft 3 includes a shaft portion 30 that rotates around the shaft center and an annular wheel mounting flange 33 that protrudes in the radial direction from the shaft portion 30, and is disposed concentrically with the outer ring 2. An outer ring 2 is mounted on the outer periphery of the shaft portion 30. The inner ring 4 is fitted on the outer peripheral surface 3 a of the vehicle inner side end portion (small diameter portion) 31 of the shaft portion 30. The wheel mounting flange 33 is for fixing the tire wheel 6 of the wheel and the brake disc rotor 7 of the brake device, and the tire wheel (wheel) 6 and the brake disc rotor 7 are attached to rotate integrally therewith. .

  Specifically, the main surface 34 of the wheel mounting flange 33 is an inlay portion that guides the radial mounting positions of the brake disc rotor 7 and the tire wheel 6 so as to protrude from the main surface 34 toward the vehicle outer side. 32 is formed, the brake disc rotor 7 abuts on the inlay portion 32 to position the brake disc rotor 7 with respect to the wheel mounting flange 33, and the tire wheel 6 abuts on the inlay portion 32 to Positioning with respect to the wheel mounting flange 33 is performed. A plurality of hub bolts inserted into the insertion holes 33 h of the hub shaft 3 are inserted into the respective mounting holes formed in the brake disc rotor 7 and the tire wheel 6, and a plurality of hub nuts 37 are inserted into the respective hub bolts 36. The tire wheel 6 is fixed to the hub shaft 3 together with the brake disc rotor 7 by being screwed.

  Next, a rotation sensor 10 is attached to the hub 1. The rotation sensor 10 detects a rotation state such as a rotation speed and a rotation direction of the hub shaft 3 and includes a pulsar ring 11 and a detection module 12. The pulsar ring 11 projects from the vehicle inner side end 41 of the inner ring 4 in the axial direction. The sensor (detecting body) 12 is arranged in the axial direction with respect to the pulsar ring 11 on the inner surface 9a side of the cap portion 9 that is attached to the outer ring 2 so as to be integrally rotatable so as to cover the vehicle inner side end opening 21h of the outer ring 2. They are arranged opposite to each other via a predetermined detection gap A.

  The pulsar ring 11 has a support portion 11b attached to the shoulder portion of the outer peripheral surface of the inner ring 4, and an annular permanent magnet member 11a attached to the support portion 11b. As shown in FIG. 2, the annular permanent magnet member 11a is composed of a ferrite-based bonded magnet in the form of a flat plate ring, and the first magnetized region N and the second magnetized magnets having different magnetic polarities by axial magnetization. The magnetic regions S are alternately arranged at equal intervals in the circumferential direction.

  3, the detection module 12 has the center of the detection module 12 coincident with the center of each magnetized region of the annular permanent magnet member 11a and the annular permanent magnet member 11a of the pulsar ring 11 Is attached to the inner side surface 9a of the protective cap 9 in a form opposed to the outer surface of the protective cap 9 through a predetermined detection gap A (air gap), corresponding to the rotational state of the annular permanent magnet member 11a. Outputs electrical signals. The protective cap 9 is fitted and fixed to the outer ring 2. The detection module 12 amplifies the magnetoelectric conversion elements that change the electrical output according to the magnetic field strength in the detection gap A, in this embodiment the Hall elements 51 and 52, and the detection outputs of the Hall elements 51 and 52, A signal processing output circuit IC that converts the amplified waveform into a square wave, converts it into a counting pulse for angle detection, and outputs it is integrated by a resin mold 12m.

  As shown in FIG. 4, the magnetic field detection elements 51 and 52 both exhibit fluctuations in the magnetic field H formed by the first magnetization region N and the second magnetization region S that pass alternately with the rotation of the pulsar ring 11. , Each of the first and second magnetized regions N and S adjacent to each other is detected as a periodic waveform formed by repeated passage. FIG. 5 shows a case where a plurality of the angular positions different from each other in the circumferential direction of the pulsar ring 11 in the case of FIG. Two are arranged. Hereinafter, the first magnetic field detection element 51 is also referred to as element 1, and the second magnetic field detection element 52 is also referred to as element 2.

  As shown in FIG. 5, the magnetic field detection elements 51 and 52 are configured so that the rising edges UE1 and UE2 and the falling edges UD1 and UD2 of the detection waveforms of the square-waved elements 1 and 2 are individually detected waveforms. Are arranged at different angular positions in the circumferential direction of the pulsar ring 11 so that the one wavelength section λ is equally divided. Specifically, when the number of arranged magnetic field detection elements 51 and 52 is n, the magnetic field detection elements 51 and 52 are in a positional relationship in which the phases of the detection waveforms are sequentially shifted by (1 / 2n) wavelengths. Since n = 2 here, the arrangement interval of the magnetic field detection elements 51 and 52 is set so that the phases of the detection waveforms of the element 1 and the element 2 are shifted from each other by (1/4) λ. It has been established.

As shown in FIG. 4, the magnetized region of the pulsar ring 11 includes a first magnetized region N and a second magnetized region S adjacent to each other within a rotation angle range θ _{λ corresponding} to one wavelength (λ) of the detected waveform. Equivalent to. Therefore, the minimum value of the arrangement interval of the magnetic field detection elements 51 and 52 for shifting the phase of the detection waveform from each other by (1/4) λ is (1/4) _θλ , and one magnetization region (N or S ) Can be arranged adjacent to each other so as to be within. In FIG. 4, the arrangement interval of the magnetic field detection elements 51 and 52 is set to the minimum value, thereby realizing a configuration in which the magnetic field detection elements 51 and 52 are integrated by a common resin mold 12m. . In the configuration of FIG. 4, when the pulsar ring 11 rotates in the direction of the arrow, the waveform of the element 1 precedes the phase of the waveform of the element 2 by (1/4) λ.

As in the prior art, when there is only one magnetic field detecting element 51, the detected waveform is a square wave as shown in FIG. If the configuration is such that only the falling edges of the waveform are counted, the angle detection resolution is about the above-mentioned θ _λ determined by the length of the NS magnetized region pair, and the rising edge and the falling edge If both are counted, the resolution becomes θ _λ / 2. However, in the present invention, as shown in FIG. 4, it is determined to which detection waveform all the rising edges UE1 and UE2 and the falling edges UD1 and UD2 of the detection waveforms squared by the two elements belong. By counting in the order of arrival in a mixed manner in time series without distinction, the resolution becomes θ _λ / 4, which is doubled as compared with the prior art.

  FIG. 6 shows a configuration example of the signal processing output circuit 60. The analog original detection waveforms of the magnetic field detection elements 51 and 52 are amplified by an amplification circuit (not shown). The amplified analog original detection waveforms are squared by the Schmitt trigger circuits 61 and 62, respectively, and become waveforms such as A and B in the figure. Although this waveform may be directly output and signal processing for edge detection / counting may be performed in the system to which the rotation sensor is connected, in this embodiment, in order to reduce the signal processing burden in the connection destination system In addition, a circuit for converting the respective edges of the waveforms A and B into angle pulse signals corresponding one-to-one and outputting them is incorporated. With this circuit, a well-known digital counter circuit 88 using a T latch circuit or the like that counts up by the falling edge input of an angle pulse can be adopted in the connection destination system, and troublesome edge detection processing becomes unnecessary.

  Specifically, the waveforms A and B whose phases are shifted by λ / 4 are input to the exclusive OR gate 53. As a result of the output of the exclusive OR gate 53, both input waveforms are C like the first pulse P derived from the rising edge UE2 of the waveform B and the falling edge DE1 of the waveform A, and the falling edge DE2 of the waveform B. The second pulse S derived from the rising edge UE1 of the waveform A is synthesized into a pulse waveform having a frequency multiplied so that the second pulse S appears alternately. The output is distributed and input to the monostable circuits 65 and 66 while the level is inverted by the inverter 64 (waveforms C and E). The monostable circuit 65 outputs a pulse waveform corresponding to the rising edge DE3 of the composite pulse waveform C (waveform D). On the other hand, the monostable circuit 66 outputs a pulse waveform corresponding to the rising edge UE3 (waveform F) because the input level is inverted. Therefore, if these waveforms D and F are input to the OR gate 67, the output is obtained as the target angle pulse waveform G.

The magnetic field detection elements 51 and 52 are not necessarily arranged adjacent to each other by utilizing the periodicity of the magnetization regions N and S on the pulsar ring 11 and the periodicity of the detection waveform formed thereby. A detection waveform equivalent to that in FIG. 5 can be obtained. For example, the minimum value of the arrangement interval between the magnetic field detection elements 51 and 52 is (1/4) θ _{λ as} described above, but when the position of the magnetic field detection element 51 is considered as a reference, the position of the magnetic field detection element 52 has a waveform. from the period of, from which (1/4) besides spaced theta _lambda, as indicated by the solid line arrows in FIG. 7, by adding an integer multiple of the wavelength _{θ λ + (1/4) θ λ} , 2θ λ + (1/4) θ _λ ,..., Nθ _λ + (1/4) θ _λ (n is an integer) is possible, and as a result, between the adjacent first and second magnetized regions N and S. The pulsar ring 11 can be distributed in the circumferential direction at an angular interval θ2 wider than the angular interval θ1. Further, in the example of FIG. 4, had positional relationship of each element is defined so that only advanced waveform element 1 (1/4) θ _λ, as shown by the broken line in FIG. 7, the element 2 waveform _(1/4) θ λ to only advance it is determined layout relations of the elements are possible.

  In addition, the number of magnetic field detection elements is not limited to two, and may be three or more. As the number increases, the resolution of angle detection can be increased. FIG. 8 shows an example in which four magnetic field detection elements 51, 52, 53 are arranged in a distributed manner. The magnetic field detection elements 51, 52, and 53 are arranged so that the phases of the detection waveforms are sequentially shifted by (1/8) wavelength.

Sectional drawing which shows an example of the hub unit used as the application object of this invention. The figure explaining pulsar ring. The figure explaining the structure of a rotation sensor. The perspective view which shows the principal part of this invention typically. FIG. 5 is a waveform diagram showing a square wave output of each magnetic field detection element of FIG. 4. FIG. 5 is a circuit diagram illustrating an example of a signal processing output circuit corresponding to the configuration of FIG. 4 together with output waveforms of respective units. Explanatory drawing which shows the 1st modification of FIG. 4 with the square wave output of each magnetic field detection element. Explanatory drawing which similarly shows a 2nd modification with the square wave output of each magnetic field detection element. The perspective view which shows the structure of the conventional bearing rotation detection apparatus. Explanatory drawing which shows the square wave output of the magnetic field detection element.

Explanation of symbols

1 Hub unit (bearing)
2 Outer ring 3 Hub axle (hub wheel)
4 Inner ring 5 Rolling element 6 Tire wheel 7 Brake disc rotor 11 Pulsar ring N First magnetized area S Second magnetized area 60 Signal processing output circuit (edge count signal output means)
61, 62 Schmitt trigger circuit (waveform shaping unit)

Claims (2)

A bearing having an inner ring, an outer ring disposed concentrically outside the inner ring, and a plurality of rolling elements disposed between the inner ring and the outer ring;
A pulsar ring that is configured as a permanent magnet member concentrically fixed to one of the inner ring and the outer ring, and in which first and second magnetized areas having different magnetic polarities are alternately formed at equal intervals; ,
The magnetic field fluctuations formed by the first and second magnetized regions that are opposed to each other in a non-rotating manner to form a magnetic gap with respect to the pulsar ring and pass alternately with the rotation of the pulsar ring. , Detecting each as a periodic waveform formed by repeatedly passing a pair of first and second magnetized regions adjacent to each other, and smaller than ½ wavelength of the periodic waveform between the detected waveforms A plurality of magnetic field detection elements arranged at different angular positions in the circumferential direction of the pulsar ring in relation to generate a phase difference,
A waveform shaping unit that squares the detection waveform of each of the magnetic field detection elements;
The counting signals corresponding to the rising and falling edges of the plurality of detection waveforms that are square-shaped are output in the order of arrival in a mixed form in time series without distinguishing which detection waveform belongs to Edge counting signal output means;
A bearing rotation detection device comprising:   The plurality of magnetic field detection elements are arranged so that a rising edge and a falling edge of each square-shaped detection waveform have a relationship in which one wavelength section of each detection waveform is equally divided from each other. The bearing rotation detection device according to claim 1, wherein the bearing rotation detection devices are arranged at different angular positions in the direction.

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