JPH10274546A - Magnetic rotation detecting system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic rotation detecting system that can detect the rotating direction of a rotor by one output signal without using two output signals of an A-phase and a B-phase. SOLUTION: A magnetic rotation detecting system has a rotor 10 rotatory- driven around a reference axis (a), a magnetic sensor 11 arranged opposedly to the peripheral surface of the rotor 10 so as to detect magnetic flux density, and a magnetic field forming means 17 for forming the magnetic field between the rotor 10 and the magnetic sensor 11. The peripheral surface of the rotor 10 is provided with a plurality of detected parts 14, 14,... with spaces from each other, and each detected part 14 is so constituted that magnetic flux density detected by the magnetic sensor 11 is increased or decreased from one end in one direction around the reference axis (a) toward the other end.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic rotation detecting system.

[0002]

2. Description of the Related Art As is well known, in a vehicle such as an automobile, it is common practice to control the vehicle by measuring the number of revolutions, the direction of rotation, the angle of rotation, etc. of an axle. 2. Description of the Related Art Conventionally, a magnetic rotation detection system has been known as a device for measuring the rotation speed of an axle of this type. FIG. 7 shows an example of this magnetic rotation detection system. In the drawing, reference numeral 1 denotes a rotating shaft, 2 denotes a rotating body, and 3 denotes a magnetic sensor. The rotating shaft 1 is rotatably supported, and is rotated by driving means (not shown). The rotating body 2 is formed of a magnetic material, and is fixed to the rotating shaft 1. The peripheral surface of the rotating body 2 has a gear-shaped rotation angle detecting section 2a having peaks and valleys formed at regular intervals over the entire circumference, and a rotational speed detection section having only one peak formed over the entire circumference. A portion 2b is formed.

[0003] The magnetic sensor 3 is disposed opposite to the peripheral surface of the rotating body 2. This magnetic sensor 3 has a first magnetoresistive element section 6 and a second magnetoresistive element section 7. These magnetoresistive element sections 6 and 7 have I
A magnetoresistive element made of n-Sb, In-NiSb, InAs, or the like is used, and detects a change in magnetic flux density corresponding to a peak or a valley formed on a rotating body 2 made of a magnetic material. ing.

[0004] The first magnetoresistive element section 6 is provided with the rotating body 2.
The rotation angle detection unit 2a is disposed to face the rotation angle detection unit 2a.
It is configured to output signals A-phase and B-phase whose phases are shifted from each other by 90 ° in accordance with the cycle of the peaks and valleys of a (see FIG. 8). The first magnetoresistive element 6
Are of a differential type for improving the S / N ratio, and as shown in FIG. 8, signals A bar phase and B bar phase having opposite phases of A phase and B phase are obtained. Therefore, as shown in FIG. 9, the first magnetoresistive element section 6 is composed of eight magnetoresistive elements 6a.

As shown in FIG. 7, the second magnetoresistive element section 7 is disposed opposite to the rotational speed detecting section 2b of the rotating body 2, and each time the rotating body 2 makes one rotation, a signal, that is, Z It is configured to output a phase (see FIG. 8).

The magnetic rotation detecting system configured as described above detects a change in magnetic flux density in the magnetic sensor 3 according to the rotation of the rotating body 2 as follows. The rotating body 2 also rotates with the rotation of the rotating shaft 1. First magnetoresistive element section 6
Are arranged to face the rotation angle detection unit 2a of the rotating body 2, so that the output signals A corresponding to the peaks and valleys of the rotation angle detection unit 2a
The phase and the B phase are output (see FIG. 8). In this case, phase A,
The B phase is a sine wave corresponding to peaks and valleys formed at regular intervals in the rotation angle detection unit 2a, so that the rotation angles of the rotating shaft 1 and the rotating body 2 can be detected from the phase of the sine wave. I have. Furthermore, since the A-phase and the B-phase are configured to be output signals shifted by 90 °, the rotation direction can be detected by comparing the A-phase and the B-phase. Since the second magnetoresistive element unit 7 is arranged to face the rotation speed detection unit 2b of the rotating body 2, it outputs a Z phase corresponding to the peak of the rotation speed detection unit 2b (see FIG. 8). In this case, the number of rotations of the rotation shaft 1 and the rotation body 2 can be detected because one peak of the rotation number detection unit 2b is formed around the entire circumference of the rotation body 2.

[0007]

The conventional magnetic rotation detecting system has the following problems. The first magnetoresistive element section 6 needs a B phase whose phase is shifted by 90 ° with respect to the A phase for detecting the rotation direction of the rotating body 2, so that a total of eight magnetoresistive elements 6 a, 6 a ... had to be provided. Therefore, the number of magnetic resistance elements cannot be reduced, and the size of the magnetic sensor 3 cannot be reduced. Therefore, this is a factor that hinders the cost reduction of the magnetic rotation detection system.

The present invention has been made in view of the above problems, and it is possible to detect the rotation direction of a rotating body with one output signal without using two output signals of A phase and B phase. It is an object of the present invention to provide a magnetic rotation detection system that performs the following.

[0009]

The magnetic rotation detecting system according to the present invention employs the following means in order to solve the above problems. A magnetic rotation detection system according to claim 1, wherein the rotating body is driven to rotate about a reference axis, and a magnetic sensor that is disposed to face a peripheral surface of the rotating body and detects a magnetic flux density;
Magnetic field forming means for forming a magnetic field between the rotating body and the magnetic sensor, a plurality of detected parts provided at intervals on a peripheral surface of the rotating body, The portions are configured such that a magnetic flux density detected by the magnetic sensor increases or decreases from one end to the other end in one direction around the reference axis.

[0010] The magnetic flux density is detected by a magnetic sensor disposed opposite to the detected portion of the rotating body. In this case, the detected portion is configured so that the magnetic flux density detected by the magnetic sensor increases or decreases from one end in one direction around the reference axis to the other end. Therefore, whether the magnetic flux density detected by the magnetic sensor increases or decreases when the detected portion passes through the position corresponding to the magnetic sensor depends on the rotation direction of the rotary body. The direction of rotation will be determined.

According to a second aspect of the present invention, in the magnetic rotation detecting system according to the first aspect, the detected portion is made of a magnetic material, and a thickness of the detected portion with respect to an imaginary circle around the reference axis is equal to the reference value. It is characterized in that it is formed so as to be thicker or thinner in one direction around the axis.

The portion to be detected is formed so that the thickness of the portion to be detected becomes thicker or thinner in one direction of the reference axis with respect to a virtual circle around the reference axis. Therefore, when the detected portion passes through the position corresponding to the magnetic sensor, the distance between the magnetic sensor and the detected portion increases or decreases according to the thickness of the detected portion. Therefore, the magnetic flux density detected by the magnetic sensor increases or decreases.

According to a third aspect of the present invention, there is provided the magnetic rotating system, wherein the rotating body is driven to rotate about a reference axis, a magnetic sensor is arranged to face the peripheral surface of the rotating body, and the rotating body and the magnetic sensor are arranged between the rotating body and the magnetic sensor. Magnetic field forming means for forming a magnetic field, wherein a plurality of detected parts are provided at intervals on a peripheral surface of the rotating body, and one of the detected parts is used as a reference target. The detecting section is formed such that a valley dimension L between the detected sections on an imaginary circle extending in one direction around the reference axis from the reference detected section increases or decreases. .

Since the valley dimension L between the detected parts on the imaginary circle extending in one direction around the reference axis from the reference detected part is configured to increase or decrease, the detection signal from the magnetic sensor is increased. Is an output waveform corresponding to the increase or decrease of the trough dimension L. Therefore, the increase or decrease of the valley dimension L is determined depending on the rotation direction of the rotating body, and the rotating direction of the rotating body is determined based on the output waveform of the magnetic sensor.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a cross-sectional view showing a first embodiment of a magnetic rotation detection system according to the present invention, wherein reference numeral 10 is a rotating body, and 11 is a magnetic sensor. The rotating body 10 is configured to be rotationally driven by a driving source (not shown) about a reference axis a in a direction orthogonal to the paper surface. A plurality of detected parts 14 are formed on the peripheral surface of the rotating body 10 at regular intervals. The detected part 14 is made of a magnetic material, and is formed so that its thickness 14a becomes thicker in the direction of the arrow b (one direction) around the reference axis a with respect to the virtual circle C1 around the reference axis a. By forming the detected portion 14 in this manner, the magnetic flux density detected by the magnetic sensor 11 from one end to the other end in the direction (one direction) of the arrow b around the reference axis a in the detected portion 14 is reduced. It is going to decrease.

The magnetic sensor 11 is arranged to face the peripheral surface of the rotating body 10. The magnetic sensor 11 has a configuration including a magnetoresistive element 16 and a permanent magnet (magnetic field forming means) 17. The magnetoresistive element section 16 is disposed at the tip of the magnetic sensor 11 on the rotating body 10 side. The magneto-resistive element section 16 has an In-
A plurality of magneto-resistive elements made of Sb, In-NiSb, InAs or the like are arranged, and the magnetic flux density in the magneto-resistive element section 16 is detected.
The permanent magnet 17 is arranged behind the magnetoresistive element 16, that is, so as to sandwich the peripheral surface of the rotating body 10 and the magnetoresistive element 16. The permanent magnet 17 is used to generate a magnetic field between the rotating body 10 and the magneto-resistive element section 16.

The output of the magnetic sensor 11 is guided to an arithmetic unit 20 via a differentiating circuit 18 and a comparator 19.

Next, a method of using the magnetic rotation detection system having the above-described configuration will be described. The rotating body 10 is rotationally driven in the direction of arrow b by a driving source (not shown). Each of the detected parts 14, 14... Formed on the rotating body 10 is provided with a magnetic sensor 11.
Approach and separate from the position corresponding to. This detected part 1
When the portion 4 passes through the position corresponding to the magnetic sensor 11, the detected portion 14 is formed so that its thickness 14a is increased in the direction of the arrow b (one direction) around the reference axis a. The distance between the magnetic sensor 11 and the detection target 14) increases, so that the magnetic flux density detected by the magnetic sensor 11 decreases. Therefore, the magnetic sensor 1
As shown in FIG. 2A, the output waveform of No. 1 once rises and then gradually decreases. When the detected part 14 does not exist at a position corresponding to the magnetic sensor 11, the magnetic flux density in the magnetic sensor 11 does not change, and the output of the magnetic sensor 11 does not change. When the detected part 14 approaches the position corresponding to the magnetic sensor 11 again,
The magnetic flux density in the magnetic sensor 11 changes, and the output of the magnetic sensor 11 changes. Due to the repetition of the approach and separation of the detected part 14 described above, the output of the magnetic sensor 11 becomes as shown in FIG.
A forward rotation waveform 22 having the shape shown in FIG.

On the other hand, when the rotating body 10 is driven to rotate in the direction opposite to the arrow b, the magnetic flux density detected by the magnetic sensor 11 is increased, contrary to the case where the rotating body 10 is driven to rotate in the direction of the arrow b. Therefore, a reverse rotation waveform 23 shown in FIG.

These outputs 22 and 23 are guided to a calculation unit 20 via a comparator 19. Comparator 19
In, the forward rotation waveform 22 and the reverse rotation waveform 23 are processed into rectangular waves by setting a threshold value Va shown in FIG. As described above, since the position of each detected part 14 is detected, the rotation angle of the rotating body 10 is calculated by the calculation part 20.

A forward rotation waveform 22 and a reverse rotation waveform 2
3 is also led to the differentiating circuit 18. This forward rotation waveform 22
Since the output rises larger than the reverse rotation waveform 23, the waveform 22a shown in FIG. On the other hand, the rising of the output of the reverse rotation waveform 23 is gentler than that of the forward rotation waveform 22, so that the waveform 23a shown in FIG. 2B is obtained. Therefore, when the threshold value Vb is set as shown in FIG. 2B, it is possible to determine the forward rotation waveform 22 and the reverse rotation waveform 23, that is, determine the rotation direction of the rotating body 10.

As described above, in the magnetic rotation detecting system according to the present embodiment, the thickness 14a of the detected portion 14 is
Since it is formed so as to be thicker in the direction, the magnetic flux density detected by the magnetic sensor 11 can be reduced from one end to the other end in the direction of the arrow b. Therefore, the output waveform of the magnetic sensor 11 at the time of normal rotation and at the time of reverse rotation differ according to the change of the magnetic flux density detected by the magnetic sensor 11, so that the rotation direction of the rotating body 10 can be determined. Therefore, the magnetic sensor 11
The rotation direction of the rotating body 10 can be detected by using only one output signal. Further, since the detected parts 14 are arranged at regular intervals, the rotation angle of the rotating body 10 can be detected at the same time.

In the present embodiment, the rotating body 10
The shape of the detected part 14 is not limited to FIG. For example, as shown in FIG. 3, a groove 25 which is missing from the virtual circle C1 around the reference axis a is formed.
The groove depth of No. 5 may be made deeper or shallower in one direction of the reference axis a. Further, as shown in FIG. 4, a plurality of detected parts 27 protruding from the peripheral surface of the rotating body are formed, and Fe or Ni is formed.
Of the detected part 27
The magnetic permeability μ may be increased or decreased from one end to the other end in one direction around the reference axis a. Also,
The number of the detected parts 14 is not limited to the number shown in the present embodiment.

Next, a second embodiment of the magnetic rotation detecting system according to the present invention will be described with reference to FIGS. In these figures, the same reference numerals are given to the same parts as those in FIG. 1 shown in the first embodiment, and the description thereof will be omitted. FIG. 5 is a sectional view showing a second embodiment, in which reference numeral 30 denotes a rotating body,
Is a detected part. The plurality of detected parts 31 are formed on the peripheral surface of the rotating body 30. These detected parts 31, 31 ...
Are formed so that the valley dimension L between the detected parts 31 on the virtual circle C1 from the reference detected part 31a toward the direction of the arrow b (one direction) around the reference axis line a increases.

The output of the magnetic sensor 11 of the magnetic rotation detecting system having the above configuration has a waveform as shown in FIG. 6A when the rotating body 30 is rotated in the direction of arrow b in FIG. In this waveform, the interval L1 between the local maximum values of the waveform becomes wider as the dimension L of the valley increases. On the other hand, when the rotating body 30 is rotated in the direction opposite to the direction of the arrow b in FIG.
The waveform is as shown in FIG. In the case of this rotation direction, when viewed from the magnetic sensor 11, it is observed that the valley dimension L decreases. Accordingly, the waveform of FIG. 6B becomes a waveform in which the interval L2 between the maximum values becomes narrower.

As described above, the interval L1 of the maximum value in the output waveform of the magnetic sensor depends on the rotation direction of the rotating body 30.
L2 is different. Therefore, the rotation direction of the rotating body 30 can be detected. If the valley dimension L is set to a known value, the rotation angle of the rotating body 30 can be detected at the same time.

[0027]

As described above, according to the magnetic rotation detecting system of the present invention, the following effects can be obtained. According to the first aspect of the present invention, the magnetic flux density detected by the magnetic sensor increases or decreases from one end in the one direction around the reference axis to the other end of the detected portion.
It is determined whether the magnetic flux density detected by the magnetic sensor increases or decreases according to the rotation direction of the rotating body, and the rotation direction can be determined. Further, if the detected parts are arranged at predetermined intervals, the rotation angle of the rotating body can be detected, so that the rotation angle and the rotation angle can be detected by one output signal without using two output signals such as A phase and B phase. The direction can be detected. Therefore, the number of magnetic resistance elements used in the magnetic sensor can be reduced, so that the size of the magnetic sensor can be reduced and the cost of the magnetic rotation detecting device can be reduced.

According to a second aspect of the present invention, in the magnetic sensor, the detected portion is formed so that the thickness of the portion to be detected becomes thicker or thinner in one direction of the reference axis with respect to a virtual circle around the reference axis. The detected magnetic flux density increases or decreases depending on the rotation direction, and the rotation direction of the rotating body can be determined.

According to a third aspect of the present invention, the valley dimension L between the detected parts on the virtual circle extending from the reference detected part in one direction around the reference axis is increased or decreased. Therefore, the increase or decrease in the valley dimension L is determined by the rotation direction of the rotating body, and the rotation direction of the rotating body can be determined.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a first embodiment of a magnetic rotation detection system according to the present invention.

2A and 2B show detection outputs of the magnetic sensor of FIG. 1; FIG. 2A shows a detection output immediately after the magnetic sensor;
FIG. 4 is a diagram showing an output after a waveform is processed by a differentiating circuit.

FIG. 3 is a cross-sectional view showing a modification of the detected part in FIG.

FIG. 4 is a cross-sectional view showing a modification of the detected part in FIG.

FIG. 5 is a sectional view showing a second embodiment of the magnetic rotation detection system according to the present invention.

6A and 6B show detection outputs of the magnetic sensor of FIG. 5, wherein FIG. 6A shows an output when the rotating body is rotated in the direction of arrow b, and FIG. Shows the output when rotated.

FIG. 7 is a front view showing a conventional magnetic rotation detection system.

8 is a diagram showing a detection output of the magnetic sensor of FIG.

FIG. 9 is a plan view showing an arrangement state of magnetoresistive elements of the magnetic sensor.

[Explanation of symbols]

 Reference Signs List 10 Rotating body 11 Magnetic sensor 14 Detected part 14a Thickness 17 Magnetic field forming means 27 Detected part 30 Rotating body 31 Detected part a Reference axis L Valley dimension C1 Virtual circle

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI G01P 13/04 G01P 13/04 C

Claims (3)

[Claims] A rotating body that is driven to rotate about a reference axis; a magnetic sensor arranged to face a peripheral surface of the rotating body to detect a magnetic flux density; and a magnetic field between the rotating body and the magnetic sensor. A plurality of detected parts are provided at intervals on the peripheral surface of the rotating body, and each of the detected parts is disposed in one direction around the reference axis. A magnetic rotation detection system, wherein a magnetic flux density detected by the magnetic sensor increases or decreases from one end to the other end. 2. The magnetic rotation detection system according to claim 1, wherein the detected portion is made of a magnetic material, and a thickness of a virtual circle around the reference axis is increased in one direction around the reference axis. A magnetic rotation detection system, which is formed so as to be thin. 3. A rotating body driven to rotate about a reference axis, a magnetic sensor arranged to face a peripheral surface of the rotating body, and a magnetic field forming means for forming a magnetic field between the rotating body and the magnetic sensor. A plurality of detected parts are provided at intervals on the peripheral surface of the rotating body, and one of the detected parts is a reference detected part,
A magnetic rotation detection system, wherein a valley dimension L between each of the detected parts on an imaginary circle extending in one direction around the reference axis from the reference detected part is increased or decreased. .