JP2016114502A - Rotation sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotation sensor with which it is possible to detect a revolution speed with high accuracy using a simple configuration.SOLUTION: A rotation sensor 1 comprises: a hall element 10 for detecting a magnetic flux density perpendicular to the outer faces of magnets 101 and disposed facing the magnets 101 on the outer circumferential face 103 of a rotor 100 provided with a plurality of magnets 101 in the circumferential direction or on one axial end face 104 of the rotor 100; a magnetoresistance effect element 20 for detecting the strength of a magnetic field based on the line of magnetic force MH parallel to the outer faces of the magnets 101 and disposed facing the magnets 101 on the outer circumferential face 103 of the rotor 100 or on one axial end face 104 of the rotor 100 where the hall element 10 is disposed; and a phase difference arithmetic unit for calculating a phase difference between a detection signal outputted as detection result from the hall element 10 and a detection signal outputted as detection result from the magnetoresistance effect element 20.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a rotation sensor that detects a rotation speed of a rotating body.

  Conventionally, sensors have been used to detect the rotation angle and rotation speed of a rotating body. This type of sensor detects the rotation angle and rotation speed of a rotating body by detecting the magnetic flux density and the strength of the magnetic field caused by magnets arranged such that different magnetic poles are adjacent to each other along the circumferential direction of the rotating body. There is something to detect. As this type of sensor, there are sensors described in Patent Documents 1 and 2, which are cited below.

  The non-contact rotation angle detection device described in Patent Document 1 is configured to include at least two sensor elements. One sensor element is operated using the magnetoresistive effect and the other sensor element is operated using the Hall effect. The output signals of these two sensor elements are combined with each other, and the rotation angle is detected based on the combined signals.

  The rotation sensor described in Patent Document 2 includes two anisotropic magnetoresistive sensors and two Hall elements. The Hall element is disposed by being laminated on the magnetoresistive element of the anisotropic magnetoresistive sensor via an insulating film.

JP 2000-515639 A JP 2012-198180 A

  The non-contact rotation angle detection device described in Patent Document 1 detects an angle between a magnetic field and a rotation angle sensor using a sensor that uses a magnetoresistive effect, and identifies a region in which the angle sensor operates using a sensor that uses a Hall effect. . The rotation sensor described in Patent Document 2 measures a deviation from a reference angle included in the sine wave signal based on a sine wave signal output from one sensor, and a cosine wave output from the other sensor. Based on the signal, a deviation from a reference angle included in the cosine wave signal is measured. As described above, in the techniques described in Patent Documents 1 and 2, signals output from a plurality of sensors are used for identification of a region in which the angle sensor operates or for measurement of signal deviation. For this reason, when the rotation direction is detected, a processing unit for performing various signal analyzes is provided, resulting in a complicated structure.

  In view of the above problems, an object of the present invention is to provide a rotation sensor capable of accurately detecting a rotation speed with a simple configuration.

  In order to achieve the above object, the rotation sensor according to the present invention is characterized by facing the magnet on the outer peripheral surface of the rotating body provided with a plurality of magnets along the circumferential direction or on one end surface in the axial direction of the rotating body. And a Hall element that detects a magnetic flux density perpendicular to the outer surface of the magnet, and an outer peripheral surface of the rotating body on which the Hall element is disposed or one axial end surface of the rotating body is opposed to the magnet. A magnetoresistive effect element that detects the strength of a magnetic field based on a magnetic field line parallel to the outer surface of the magnet, a detection signal output as a detection result from the Hall element, and a detection result from the magnetoresistive element And a phase difference calculator that calculates a phase difference from the output detection signal.

  With such a characteristic configuration, the detection direction of the magnetic flux density of the Hall element is set perpendicular to the outer surface of the magnet, and the detection direction of the magnetic field strength of the magnetoresistive effect element is set to the outer surface of the magnet. It can be set in a parallel direction. For this reason, since the Hall element and the magnetoresistive effect element are arranged so that their detection directions are orthogonal to each other, the detection signals output as detection results from the Hall element and the magnetoresistive effect element have the same period and amplitude. In addition, the phase difference between the detection signal output as the detection result from the Hall element and the detection signal output as the detection result from the magnetoresistive effect element is a constant phase difference. Therefore, the reliability of the detection result is improved by detecting the rotation speed of the rotating body using one of the detection result of the Hall element and the detection result of the magnetoresistive element while confirming that the phase difference is constant. Therefore, it is possible to accurately detect the rotational speed of the rotating body with a simple configuration.

  Further, it is preferable that a rotation direction detection unit that detects a rotation direction of the rotating body based on the phase difference is provided.

  As described above, since the Hall element and the magnetoresistive effect element are arranged so that their detection directions are orthogonal to each other, the detection signal output as a detection result from the Hall element and the magnetoresistive effect element has a predetermined phase difference. Will have. Therefore, with this configuration, it is possible to detect whether the phase difference between the detection signal output as the detection result from the Hall element and the detection signal output as the detection result from the magnetoresistive effect element is an advance or a delay. Thus, it is possible to easily specify the rotation direction of the rotating body.

  An abnormality determination unit that determines whether the detection signal output as the detection result from the Hall element and the detection signal output as the detection result from the magnetoresistive effect element are abnormal based on the phase difference. It is suitable to provide.

  If there is no abnormality in the rotation sensor, detection signals output as detection results from the Hall element and the magnetoresistive effect element are output with a predetermined phase difference. For this reason, when the phase difference of the detection signal output as a detection result from the Hall element and the magnetoresistive effect element deviates from an intended value, it can be determined that the rotation sensor is abnormal. Therefore, as in this configuration, it is determined whether or not the phase difference between the detection signal output as the detection result from the Hall element and the detection signal output as the detection result from the magnetoresistive element deviates from the intended value. This makes it possible to easily determine whether or not the rotation sensor is abnormal.

It is the figure which showed the structure of the rotation sensor. It is an example of arrangement | positioning of a rotation sensor. It is a figure which shows the magnetic field and magnetic flux density which generate | occur | produce around a rotary body. It is the figure which showed the circuit structure of the rotation sensor. It is a figure which shows the output signal of a Hall element and a magnetoresistive effect element, and the output signal of a rotation sensor.

  The rotation sensor according to the present invention is simply configured with a function of detecting the rotation speed of the rotating body with high accuracy. Hereinafter, the rotation sensor 1 of the present embodiment will be described. In the rotation sensor 1, a Hall element 10, a magnetoresistive effect element 20, and a signal processing unit 30 are integrated as a sensor IC. The signal processing unit 30 includes a phase difference calculation unit 32, a rotation direction detection unit 33, and an abnormality determination unit 34, which will be described later. FIG. 1 shows a perspective view in which such an integrated rotation sensor 1 is made transparent.

  As shown in FIG. 1, the Hall element 10, the magnetoresistive effect element 20, and the signal processing unit 30 are encapsulated with resin while being mounted on a lead frame 70. Thus, the resin-encapsulated portion corresponds to the mold portion 72. The mold portion 72 is provided with a pair of lead terminals 71 that constitute the lead frame 70. One of the lead terminals 71 is used as a power supply terminal for supplying power, and the other is used as an output terminal for outputting a reference potential and an output result.

  Such a rotation sensor 1 is used to detect the rotation speed of the rotating body 100. As shown in FIG. 2, the rotating body 100 as the detection target is provided with a plurality of magnets 101 so that different magnetic poles are adjacent to each other along the circumferential direction. Accordingly, the lines of magnetic force caused by the magnet 101 generated around the rotating body 100 change according to the rotation of the rotating body 100 about the axis X as the rotation axis. The rotation sensor 1 is arranged so as to be able to detect the magnetic flux density and the magnetic field strength based on the magnetic field lines that change in accordance with the rotation of the rotating body 100 in this way.

  In the present embodiment, the magnet 101 is provided on the outer edge portion 102 of the rotating body 100. In order to easily detect the above-described magnetic flux density and magnetic field strength of the magnet 101, the rotation sensor 1 is arranged to face the magnet 101 on the outer peripheral surface 103 of the rotating body 100 or one end surface 104 in the axial direction of the rotating body 100. Is done. When the rotation sensor 1 is provided on the outer peripheral surface 103 of the rotating body 100 so as to face the magnet 101, the rotation sensor 1 has a magnetic flux density and a magnetic field strength based on the magnetic lines of force of the magnet 101 generated on the radially outer side of the rotating body 100. Will be detected. On the other hand, when the rotation sensor 1 is provided to face the magnet 101 on one end face 104 in the axial direction of the rotating body 100, the rotation sensor 1 is based on the magnetic force lines of the magnet 101 generated on one side in the axial direction of the rotating body 100. The magnetic flux density and the magnetic field strength are detected. In the example of FIG. 2, the rotation sensor 1 is provided to face one end face 104 in the axial direction of the rotating body 100.

  FIG. 3 shows a partially enlarged view of the rotation sensor 1 and the rotating body 100 shown in FIG. 2 as viewed in the Y direction. The Hall element 10 detects a magnetic flux density perpendicular to the outer surface of the magnet 101. Magnetic field lines corresponding to the magnetic poles (N pole and S pole) as shown in FIG. 3 are generated around the magnet 101. The outer surface of the magnet 101 is a surface on which the Hall element 10 faces, and corresponds to one end surface 104 in the axial direction of the rotating body 100 in the present embodiment. For this reason, the magnetic flux density perpendicular to the outer surface is the magnetic flux density based on the magnetic field lines in the Z direction to which the symbol MV is attached in the example of FIG. Therefore, the Hall element 10 is arranged so that the detection direction of the magnetic flux density coincides with the direction perpendicular to the outer surface of the magnet 101. Thereby, it becomes possible to detect the magnetic flux density based on the magnetic field lines MV in the direction perpendicular to the outer surface of the magnet 101 according to the rotation of the rotating body 100.

  Here, in the present embodiment, the magnetoresistive effect element 20 has four resistors constituting a bridge circuit. The magnetoresistive effect element 20 composed of these four resistors is provided so as to be laminated with the Hall element 10 as shown in FIGS. Therefore, the magnetoresistive effect element 20 is disposed to face the magnet 101 on the outer peripheral surface 103 of the rotating body 100 on which the Hall element 10 is disposed or on one end face 104 in the axial direction of the rotating body 100. In the present embodiment, as described above, the Hall element 10 is arranged opposite to the magnet 101 on the one end surface 104 in the axial direction of the rotating body 100, so that the magnetoresistive effect element 20 is also one end surface in the axial direction of the rotating body 100. In 104, it is arranged to face the magnet 101.

  The magnetoresistive effect element 20 detects the strength of the magnetic field based on the magnetic field lines parallel to the outer surface of the magnet 101. The magnetic force lines parallel to the outer surface of the magnet 101 correspond to magnetic force lines parallel to the X direction in FIG. In the example of FIG. 3, the magnetic field lines in the X direction to which the reference sign MH is attached correspond to the magnetic field lines MH. Therefore, the magnetoresistive effect element 20 is arranged so that the detection direction of the magnetic field coincides with the direction parallel to the outer surface of the magnet 101. Here, since the magnetoresistive effect element 20 is publicly known, detailed description thereof is omitted, but the magnetoresistive effect element 20 has an electric resistance according to the strength of the surrounding magnetic field where the magnetoresistive effect element 20 is disposed. It is a changing resistor. Therefore, the strength of the magnetic field can be detected by configuring a bridge circuit with such a resistor and measuring the output of the bridge circuit. By using such a magnetoresistive effect element 20, it is possible to detect the strength of the magnetic field based on the magnetic field lines MH parallel to the outer surface of the magnet 101 according to the rotation of the rotating body 100. As the magnetoresistive effect element 20, for example, a GMR element (giant magnetoresistive effect element) or a TMR element (tunnel magnetoresistive effect element) can be used.

  FIG. 4 is a diagram illustrating a circuit configuration of the signal processing unit 30 of the rotation sensor 1. The signal processing unit 30 is provided with the Hall element 10 and the magnetoresistive effect element 20 connected thereto. As described above, the Hall element 10 and the magnetoresistive effect element 20 are provided in the mold unit 72 together with the signal processing unit 30. It is done.

  The outputs of the Hall element 10 and the magnetoresistive effect element 20 are input to the preamplifier 30A, respectively. In the preamplifier 30A, the offset is adjusted by the offset adjustment circuit 30E according to the calculation result of the calculation unit 30D described later. The output of the preamplifier 30A is input to the main amplifier 30B, and the signal is amplified with a predetermined amplification factor. In the main amplifier 30B, the signal is amplified with the amplification factor set by the amplification factor adjustment circuit 30F in accordance with the computation result of the computation unit 30D described later.

  The outputs of the main amplifier 30B are input to the AD converter 30C, respectively. The detection signal output as the detection result from the Hall element 10 and the detection signal output as the detection result from the magnetoresistive effect element 20 are analog signals, respectively. In the AD converter 30C, such an analog signal is converted into a digital signal. The signal converted into a digital signal by the AD converter 30C is transmitted to the arithmetic unit 30D described later.

  The calculation unit 30D includes a threshold setting unit 31, a phase difference calculation unit 32, a rotation direction detection unit 33, and an abnormality determination unit 34. Here, in the present embodiment, the rotation sensor 1 includes the Hall element 10 and the magnetoresistive effect element 20, but the rotational speed of the rotating body 100 is the same as that of one of the Hall element 10 and the magnetoresistive effect element 20. It is possible to detect only by the detection result. In the present embodiment, the rotational speed of the rotating body 100 is detected using the detection result of the magnetoresistive effect element 20. Therefore, the output of the main amplifier 30B that amplifies the signal from the magnetoresistive effect element 20 is input to the comparator 30G. In this embodiment, the detection signal of the magnetoresistive effect element 20 after amplification is input to the non-inverting terminal of the comparator 30G, and the signal to be compared with the signal is set by the threshold setting unit 31 and input to the inverting terminal. The threshold value set by the threshold value setting unit 31 can be set to an arbitrary value. For example, it is preferable to set the threshold value to 30% or 70% with respect to the amplitude of the detection signal of the magnetoresistive effect element 20. . Thereby, the output of the comparator 30G is output from one of the pair of lead terminals 71, and the rotational speed of the rotating body 100 can be detected according to the output. The comparator 30G is preferably a Schmitt trigger type in order to prevent malfunction.

  The phase difference calculator 32 calculates the phase difference between the detection signal output as the detection result from the Hall element 10 and the detection signal output as the detection result from the magnetoresistive effect element 20. In the present embodiment, as described above, the Hall element 10 detects the magnetic flux density based on the magnetic force lines MV in the direction perpendicular to the outer surface of the magnet 101, and the magnetoresistive effect element 20 is in a direction parallel to the outer surface of the magnet 101. The strength of the magnetic field based on the magnetic field lines MH is detected. Therefore, a predetermined phase difference is generated between the detection signal output from the Hall element 10 and the detection signal output from the magnetoresistive effect element 20. The phase difference calculation unit 32 calculates such a phase difference.

Here, in the present embodiment, as described above, the magnetoresistive effect element 20 is provided by being stacked on the Hall element 10. Therefore, the phase difference between the detection signal output from the Hall element 10 and the detection signal output from the magnetoresistive effect element 20 is approximately 90 degrees as shown in FIG.

  Therefore, it is confirmed that the phase difference between the detection signal output as the detection result from the Hall element 10 calculated by the phase difference calculation unit 32 and the detection signal output as the detection result from the magnetoresistive effect element 20 is constant. By doing so, it can be recognized that the detection result of the Hall element 10 and the detection result of the magnetoresistive effect element 20 are accurate, and the reliability of the detection result can be improved.

  The rotation direction detection unit 33 detects the rotation direction of the rotating body 100 based on such a phase difference. That is, when the detection signal of the Hall element 10 is detected with a delay of 90 degrees from the detection signal of the magnetoresistive effect element 20 as shown in FIG. 5A, the rotating body 100 rotates in the positive direction, and the magnetoresistance When the detection signal of the Hall element 10 is detected 90 degrees ahead of the detection signal of the effect element 20, the rotation direction is specified on the assumption that the rotating body 100 is rotating in the reverse direction. As described above, the rotation sensor 1 can easily detect the rotation direction of the rotating body 100 even when only one rotation sensor 1 is used.

  In addition, the abnormality determination unit 34 determines whether the detection signal output as the detection result from the Hall element 10 and the detection signal output as the detection result from the magnetoresistive effect element 20 are abnormal based on the phase difference. judge. That is, as described above, the detection signal of the Hall element 10 and the detection signal of the magnetoresistive effect element 20 are detected with a predetermined phase difference. Therefore, when the phase difference is greatly deviated or when the detection signal of the Hall element 10 and the detection signal of the magnetoresistive effect element 20 do not follow the previous detection signal with the intended phase difference. It can be determined that any part of the rotation sensor 1 is abnormal, that is, the rotation sensor 1 has failed.

  Next, the detection result of the rotation sensor 1 will be described. FIG. 5A shows the detection signal of the Hall element 10, the detection signal of the magnetoresistive effect element 20, and the threshold signal set by the threshold setting unit 31. When the rotation direction detection unit 33 specifies that the rotation direction of the rotating body 100 is the positive direction based on the phase difference between the detection signal of the Hall element 10 and the detection signal of the magnetoresistive effect element 20, FIG. ), A high signal is output for a predetermined period (eg, T1) after the detection signal of the Hall element 10 exceeds the threshold signal, and the rotation direction detection unit 33 detects the detection signal of the Hall element 10. And the detection signal of the magnetoresistive effect element 20, when it is specified that the rotation direction of the rotating body 100 is the reverse direction, as shown in FIG. It may be configured to output a high signal only for a predetermined period (for example, T2) different from when the rotation direction is the positive direction after the signal exceeds the threshold signal. Thereby, the rotational speed of the rotating body 100 can be detected by calculating the period of the high signal in the output signal of the comparator 30G. It is also possible to indicate the rotation direction of the rotating body 100 according to the length of the high signal.

  Further, when the abnormality determination unit 34 determines that the rotation sensor 1 is abnormal, as shown in FIG. 5D, a period (for example, T3) longer than the above-described period (T1 or T2). During this time, a high signal may be output, or a signal may not be output at all as shown in FIG.

[Other Embodiments]
In the above embodiment, in FIG. 2, the rotation sensor 1 is illustrated as being disposed opposite to the magnet 101 on one end surface 104 in the axial direction of the rotating body 100, but the rotation sensor 1 is illustrated on the outer peripheral surface 103 of the rotating body 100. You may arrange | position facing the magnet 101. FIG.

  In the above embodiment, the rotation direction detection unit 33 has been described as detecting the rotation direction of the rotating body 100 based on the phase difference between the detection result of the Hall element 10 and the detection result of the magnetoresistive effect element 20. 10 and the magnetoresistive effect element 20 may be provided in two pairs, and the rotational direction may be detected by the phase difference between the two. Thereby, detection sensitivity can be increased.

  In the above embodiment, the abnormality determination unit 34 has been described as determining whether or not the rotating body 100 is abnormal based on the phase difference between the detection result of the Hall element 10 and the detection result of the magnetoresistive effect element 20. It is also possible to configure the rotation sensor 1 without providing the abnormality determination unit 34 and not to determine whether or not the rotation sensor 1 is abnormal.

  The present invention can be used for a rotation sensor that detects the rotation speed of a rotating body.

DESCRIPTION OF SYMBOLS 1: Rotation sensor 10: Hall element 20: Magnetoresistive effect element 32: Phase difference calculating part 33: Rotation direction detection part 34: Abnormality determination part 100: Rotating body 101: Magnet 103: Outer peripheral surface 104: One axial end surface MH : Magnetic field lines

Claims (3)

A hole for detecting a magnetic flux density perpendicular to the outer surface of the magnet, arranged on the outer peripheral surface of the rotating body provided with a plurality of magnets along the circumferential direction or on one end surface in the axial direction of the rotating body. Elements,
Detecting the strength of the magnetic field based on the magnetic field lines arranged opposite to the magnet on the outer peripheral surface of the rotating body on which the Hall element is disposed or one axial end surface of the rotating body and parallel to the outer surface of the magnet. A magnetoresistive element;
A phase difference calculation unit for calculating a phase difference between a detection signal output as a detection result from the Hall element and a detection signal output as a detection result from the magnetoresistive element;
A rotation sensor.   The rotation sensor according to claim 1, further comprising a rotation direction detection unit that detects a rotation direction of the rotating body based on the phase difference.   An abnormality determination unit that determines whether the detection signal output as a detection result from the Hall element and the detection signal output as a detection result from the magnetoresistive element based on the phase difference is abnormal. The rotation sensor according to claim 1 or 2.

Images