JPH08201015A - Angle of rotation detector - Google Patents

Abstract

PURPOSE: To obtain a detector which allows the minimizing of variations in output because of a change in outside temperature without using a temperature correction circuit by arranging a thermosensitive magnetic body in proximity to a magnet. CONSTITUTION: A thermosensitive magnetic body 14a is connected on the side of a magnet 4 between magnetized surfaces 4a and 4a. A magneto-electric transducer 1, a magnet 4, a rotating shaft 5 and the thermosensitive magnetic body 14a form a magnetic circuit. As the temperatures of the magneto-electric transducer 1, the magnet 4 and the thermosensitive magnetic body 14a rise with an external environment changing, a variation of a resistance value reduces with respect to the intensity of a magnetic field of the magneto-electric transducer 1. At the same time, the saturated flux density of the thermosensitive magnetic body 14a lowers. As a result, the flux density passing through the thermosensitive magnetic body 14a arranged on the side of the magnet 4 reduces to increase a leakage magnetic flux. The change in temperature is limited in the flux density of the magnet 4. Therefore, the flux density to be applied to a magnetoresistance effect element increases. This causes a larger variation of a resistance value thereby correcting a decrease in the variation of the resistance value associated with a rise in the temperature.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotation angle detecting device which outputs an electric signal corresponding to a rotation angle.

[0002]

2. Description of the Related Art Conventionally, as a rotation angle detecting device for detecting a rotation angle or a rotation position, a device using a magnetoresistive element has been put to practical use for constructing a non-contact mechanism or for reducing an inertial mass during rotation. Has been converted. Such a rotation angle detecting device is shown in FIGS. 5 is a sectional view and FIG. 6 is an explanatory view.

As shown in FIG. 5, the rotation angle detecting device 50 has a case 3 in which a magneto-electric conversion element 1, a temperature correction circuit 2, and a rotating shaft 5 having a magnet 4 are housed. Each component will be described in detail below.

The case 3 comprises a case lid portion 3a and a case bottom portion 3b, and a bearing portion 6 is provided at the center of the case lid portion 3a. The bearing 6 includes a ball bearing 6a,
The rotary shaft 5 is supported via 6a. The magnet 4 is attached to the tip of the rotating shaft 5 such that the direction perpendicular to the magnetizing surfaces 4a and 4a is parallel to the central axis 5a of the rotating shaft 5 and the center of the magnetizing surface 4a is displaced from the central axis 5a. Has been. On the bottom 3b of the case, the two-element one-chip type magneto-electric conversion element 1 is placed with its center aligned with the central axis 5a of the rotary shaft 5, and further connection terminals 11, 11, 11 for external connection. It has been derived.

The connection state of the magnetoelectric conversion element 1 and the temperature correction circuit 2 will be described with reference to FIG. The magnetoelectric conversion element 1 is a magnetoresistive effect element 8a, 8b having a pair of meander line shapes.
The respective ends are connected to each other, and the connection point 12 is connected to the connection electrode 7a. Magnetoresistive element 8
Connection electrodes 7b and 7b are connected to the other ends of a and 8b, respectively. One end of the temperature correction circuit 2 in which a resistor 9a and a thermistor 10 are connected in parallel is connected to the connection electrode 7a. The other end of the temperature correction circuit 2 and the connection electrodes 7b, 7b
Are respectively connected to the connection terminals 11, 11, 11 derived from the case bottom portion 3b shown in FIG. Furthermore, resistors 9b and 9b are connected between the connection terminals 11, 11 and 11.

Next, the operation of the rotation angle detecting device 50 will be described. When the rotating shaft 5 connected to an external rotating body (not shown) rotates, the magnet 4 attached to the rotating shaft 5 rotates,
Part of the magnetic field generated by the magnet 4 is applied to the magnetoresistive effect elements 8a and 8b, respectively. In FIG. 6, the resistance change portion 13 in which the magnetic field of the magnet 4 is applied to the magnetoresistive effect elements 8a and 8b is shown by a broken line. When the magnet 4 rotates, magnetic fields having different values H1 and H2 are applied to the magnetoresistive effect elements 8a and 8b, so that the resistance of the magnetoresistive effect elements 8a and 8b depends on the magnetic field strengths H1 and H2. Resistance values R1 and R2
Becomes Due to this difference in resistance value ΔR = R1-R2, the potential of the connecting portion 12 of the magnetoresistive effect elements 8a and 8b changes,
The potential corresponding to the rotation angle is output from the connection terminal 11 via the connection electrode 7a.

[0007]

However, since the resistance value of the magnetoresistive effect element, which is a component of the rotation angle detecting device having the above-described structure, changes with temperature, the rotation angle detecting device shown in FIG. As shown, the temperature compensating circuit 2 in which the resistor 9a and the thermistor 10 are connected in parallel is required.

The present invention has been made in order to solve the above problems, and provides a rotation angle detecting device in which the fluctuation of the output due to the change of the external temperature is reduced without using the temperature correction circuit.

[0009]

According to a first aspect of the present invention, there is provided a rotation angle detecting device, which includes a rotating shaft rotatably supported and a magnetoelectric conversion element arranged axially of the rotating shaft. And a magnet arranged so that the direction of the line connecting the centers of the two opposing magnetic poles coincides with the axial direction of the rotating shaft and the line connecting the centers of the opposing magnetic poles is displaced from the center of the rotating shaft, And a temperature-sensitive magnetic body arranged close to the magnet.

A rotation angle detecting device according to a second aspect of the present invention is characterized in that the magnet is composed of a single magnet, and the temperature-sensitive magnetic body is arranged on a side surface or an end surface of the magnet.

A rotation angle detecting device according to a third aspect of the present invention is characterized in that the magnet is composed of a single magnet, and a temperature-sensitive magnetic material is arranged on each of a side surface and an end surface of the magnet. A rotation angle detecting device according to a fourth aspect of the present invention is characterized in that the magnet is composed of a plurality of magnets, and the temperature-sensitive magnetic body is arranged on a side surface or an end surface of at least one of the magnets.

According to a fifth aspect of the present invention, there is provided a rotation angle detecting device comprising a plurality of the magnets, and at least one of the magnets is provided with a temperature-sensitive magnetic material on an end surface and a side surface thereof. To do.

[0013]

In the rotation angle detecting device according to the first aspect of the invention, since the temperature-sensitive magnetic material is arranged in parallel with the magnet member, the temperature-corrected magnetic field can be applied to the magnetoelectric conversion element. Since the rotation angle detecting device according to claim 2 has a single magnet and the temperature-sensitive magnetic body arranged on the side surface or the end surface of the magnet, a temperature-corrected magnetic field can be applied to the magnetoelectric conversion element. it can.

In the rotation angle detecting device according to the third aspect of the invention, since the single magnet and the temperature-sensitive magnetic body are arranged on the side surface and the end surface of the magnet, the temperature-corrected magnetic field is applied to the magnetoelectric conversion element. can do.

In the rotation angle detecting device according to the fourth aspect of the present invention, since the plurality of magnets and the temperature-sensitive magnetic bodies are respectively arranged on the side surfaces or the end surfaces of these magnets, the temperature-corrected magnetic field is applied to the magnetoelectric conversion element. can do.

In the rotation angle detecting device according to the fifth aspect of the present invention, since the plurality of magnets and at least one of the magnets, the temperature-sensitive magnetic body is arranged on the side surface and the end surface, respectively,
A temperature-corrected magnetic field can be applied to the magnetoelectric conversion element.

[0017]

【Example】

(Embodiment 1) A rotation angle detecting device 20 according to an embodiment of the present invention will be described below with reference to the sectional view of FIG. The same parts as those in the conventional example are designated by the same reference numerals, and the description thereof will be omitted.

As shown in FIG. 1, a rotation angle detecting device 20 according to the present invention comprises a magnetoelectric conversion element 1, a magnet 4, a temperature-sensitive magnetic body 14a, and a rotary shaft 5 housed in a case 3. Has been done. The magnetoelectric conversion element 1 is attached to the center of the case bottom portion 3b. The rotating shaft 5 is attached to a bearing portion 6 formed at the center of the case lid portion 3a via a ball bearing 6a. At the lower end of the rotary shaft 5, the magnet 4 is at a position displaced from the central axis 5a of the rotary shaft 5, and the magnetized surface 4
It is attached so that the direction perpendicular to a and 4a coincides with the rotation axis direction. The temperature-sensitive magnetic body 14a is on the side surface of the magnet 4 and is connected between the magnetized surfaces 4a and 4a. The magnetoelectric conversion element 1, the magnet 4, the rotating shaft 5, and the temperature-sensitive magnetic body 14a are
A magnetic circuit is formed similarly to the conventional rotation angle detection device 50. Next, the operation of the rotation angle detection device 20 will be described.
When the rotating shaft 5 connected to the external rotating body (not shown) rotates, the magnet 4 attached to the rotating shaft rotates,
The strength of the magnetic field applied to the magnetoresistive effect element (not shown in FIG. 1) changes, and the resistance value of the magnetoresistive effect element changes. The rotation angle detection device 20 detects the change in the resistance value so that the rotation angle or the rotation speed of the rotating body attached to the outside can be detected.

When the external environment changes and the temperatures of the magnetoelectric conversion element 1, the magnet 4, and the temperature-sensitive magnetic substance 14a rise, as is widely known, the amount of change in the resistance value with respect to the magnetic field strength of the magnetoelectric conversion element 1. Becomes smaller. At the same time, the saturation magnetic flux density of the temperature-sensitive magnetic body 14a decreases. Therefore, the magnetic flux density passing through the temperature-sensitive magnetic body 14a arranged on the side surface of the magnet 4 becomes small, and the leakage magnetic flux increases. Further, the temperature change of the magnetic flux density of the magnet 4 is small. Therefore, the magnetic flux density applied to the magnetoresistive effect element increases. As a result, the amount of change in the resistance value becomes large, and the decrease in the amount of change in the resistance value due to the temperature rise is corrected. That is, the output of the rotation angle detection device 20 does not change with temperature.

Further, when the temperature of the rotation angle detecting device 20 decreases, a change in the magnetic flux density opposite to the above-mentioned change occurs, and the output of the rotation angle detecting device 20 also does not change with respect to the temperature.

The magnetoelectric conversion element 1 may be mounted on the case bottom portion 3b via a yoke made of a soft magnetic material in order to attract a magnetic flux.

(Embodiment 2) A rotation angle detecting device 30 according to another embodiment of the present invention will be described below with reference to the sectional view of FIG. The same parts as those in the conventional example are designated by the same reference numerals and the description thereof will be omitted.

As shown in FIG. 2, in the rotation angle detecting device 30 according to the present invention, the magnetoelectric conversion element 1, the magnets 4, 44, the temperature-sensitive magnetic body 14a, and the rotating shaft 5 are housed in the case 3. Is configured. The magnetoelectric conversion element 1 is attached to the center of the case bottom portion 3b. The rotating shaft 5 is attached to a bearing portion 6 formed at the center of the case lid portion 3a via a ball bearing 6a. At the lower end of the rotating shaft 5, a magnet 4,
44 is a position displaced from the central axis 5a of the rotary shaft 5,
The magnetized surfaces 4a and 4a are attached so that the direction perpendicular to the magnetized surfaces 4a and 4a coincides with the rotation axis direction. The temperature-sensitive magnetic body 14a is on the side surface of the magnet 4 and is connected between the magnetized surfaces 4a and 4a. The magnetoelectric conversion element 1, the magnets 4, 44, the rotating shaft 5, and the temperature-sensitive magnetic body 14a form a magnetic circuit like the conventional rotation angle detecting device 50.

Next, the operation of the rotation angle detecting device 30 will be described. When the rotating shaft 5 connected to the external rotating body (not shown) rotates, the magnet 4 attached to the rotating shaft 5 rotates, so that the strength of the magnetic field applied to the magnetoresistive effect elements 8a and 8b changes. However, the resistance values of the magnetoresistive effect elements 8a and 8b change. The rotation angle detection device 30 detects the change in the resistance value so as to detect the rotation angle or the rotation speed of the rotating body attached to the outside.

When the external environment changes and the temperatures of the magnetoelectric conversion element 1, the magnets 4, 44, and the temperature-sensitive magnetic material 14a rise, the amount of change in the resistance value with respect to the change in the magnetic flux density of the magnetoresistive effect elements 8a, 8b decreases. At the same time, the saturation magnetic flux density of the temperature-sensitive magnetic body 14a decreases.

On the other hand, the temperature change of the saturation magnetic flux density of the magnets 4, 44 is smaller than the temperature change of the magnetic flux density of the temperature-sensitive magnetic substance 14a. Further, since the saturation magnetic flux density of the temperature-sensitive magnetic body 14a is lowered, the magnetoresistive effect element 8 is interposed via the temperature-sensitive magnetic body 14a.
The magnetic flux density due to the magnet 44 applied to a and 8b decreases. That is, of the resistance value changes of the magnetoresistive effect elements 8a and 8b, the change amount R1 by the magnet 4 does not change, but the change amount R2 by the magnet 44 becomes small. That is, since the resistance change amount ΔR = R1−R2 becomes large, the output of the magnetoelectric conversion element due to ΔR is corrected to increase.

Therefore, the output decrease due to the temperature rise is corrected by the temperature change of the magnetic flux density, and the output of the rotation angle detecting device is kept constant.

Further, when the temperature of the rotation angle detecting device 30 decreases, a change in the magnetic flux density opposite to the change described above occurs, and the output of the rotation angle detecting device 30 does not change with respect to the temperature.

The magnetoelectric conversion element 1 may be mounted on the case bottom portion 3b via a yoke made of a soft magnetic material in order to attract a magnetic flux.

(Third Embodiment) Another embodiment of the rotation angle detecting device 40 according to the present invention will be described below with reference to the sectional view of FIG. The same parts as those in the conventional example are designated by the same reference numerals and the description thereof will be omitted.

As shown in FIG. 3, in the rotation angle detecting device 40 according to the present invention, the magnetoelectric conversion element 1 is attached to the case bottom portion 3b, and the magnets 4 and 44 and the temperature-sensitive magnetic bodies 14a and 14b are used.
A rotary shaft 5 having the above is rotatably attached to the case lid portion 3a. The temperature-sensitive magnetic body 14a is located on the side surface of the magnet 4 and is connected between the magnetized surfaces 4a and 4a.
Is connected to the end surface of the magnet 44. Since the temperature-sensitive magnetic bodies 14a and 14b are attached to the magnets 4 and 44, magnetic fields of different magnitudes are applied to the magnetoelectric conversion element 1 by the magnets 4 and 44.

Next, the operation of the rotation angle detecting device 40 will be described. When the rotating shaft 5 connected to an external rotating body (not shown) rotates, the magnets 4 and 44 attached to the rotating shaft rotate, so that the strength of the magnetic field applied to the magnetoresistive effect elements 8a and 8b increases. It changes and its resistance value changes. The rotation angle detection device 40 detects the change in the resistance value,
It works so that the rotation angle or number of rotations of the rotating body attached to the outside can be detected.

When the external environment changes and the temperatures of the magnetoelectric conversion element 1, the magnets 4, 44 and the temperature sensitive magnetic bodies 14a, 14b rise, the saturation magnetic flux density of the temperature sensitive magnetic bodies 14a, 14b lowers.

The temperature change of the magnetic flux density of the magnet 4 is smaller than the temperature change of the magnetic flux density of the temperature-sensitive magnetic body 14a. Further, when the temperature rises, the magnetic flux density passing through the temperature-sensitive magnetic body 14a decreases, and the leakage magnetic flux increases. That is, the magnetic flux density applied to the magnetoresistive effect elements 8a and 8b by the magnet 4 increases. Further, the temperature-sensitive magnetic body 1 attached to the magnet 44
The saturation magnetic flux density of 4b decreases as the temperature rises, and the strength of the magnetic field generated by the magnet 44 decreases near the magnetoresistive effect elements 8a and 8b. That is, the strength of the magnetic field applied to the magnetoresistive effect elements 8a and 8b is reduced by the magnet 44. As a result, the resistance change R1 due to the magnet 4 increases and the resistance change R2 due to the magnet 44 decreases, so that the resistance change amount ΔR = R1−R2 increases, and the output of the magnetoelectric conversion element 1 due to ΔR increases. Is corrected to.

Therefore, the output decrease due to the temperature rise is corrected by the temperature change of the magnetic flux density, and the output of the rotation angle detecting device is kept constant.

As shown in the sectional view of FIG. 4, the temperature-sensitive magnetic bodies 14a and 14b are provided on the side surface and the magnetized surface of one magnet 4, respectively.
The structure may be attached. In addition, the magnetoelectric conversion element 1
May be placed on the case bottom 3b via a yoke made of a soft magnetic material in order to attract a magnetic flux.

[0037]

According to the rotation angle detection device of the first aspect of the present invention, since the temperature-sensitive magnetic body is arranged in parallel with the magnet, the output of the magnetoresistive effect element is corrected with respect to the change of the external temperature. The output of the rotation angle detection device can be kept constant.

Since the rotation angle detecting device according to claim 2 of the present invention has a single magnet and a temperature-sensitive magnetic material arranged on the side surface or the end surface of the magnet, It is possible to correct the output of the magnetoresistive effect element and keep the output of the rotation angle detection device constant.

Since the rotation angle detecting device according to the third aspect of the present invention has the single magnet and the temperature-sensitive magnetic material arranged on the side surface and the end surface of these magnets, It is possible to correct the output of the magnetoresistive effect element and keep the output of the rotation angle detection device constant.

In the rotation angle detecting device according to the fourth aspect of the present invention, since the plurality of magnets and the temperature-sensitive magnetic bodies are arranged on the side surfaces and the end surfaces of these magnets respectively, It is possible to correct the output of the magnetoresistive effect element and keep the output of the rotation angle detection device constant.

Since the rotation angle detecting device according to the fifth aspect of the present invention has the plurality of magnets and the temperature-sensitive magnetic substance arranged on the end surface having the magnetic pole of at least one of the magnets, the external temperature It is possible to correct the output of the magnetoresistive effect element in response to the change of, and keep the output of the rotation angle detection device constant.

[Brief description of drawings]

FIG. 1 is a sectional view of a rotation angle detection device according to an embodiment of the present invention.

FIG. 2 is a sectional view of a rotation angle detection device according to another embodiment of the present invention.

FIG. 3 is a sectional view of a rotation angle detection device according to another embodiment of the present invention.

FIG. 4 is a sectional view of a rotation angle detection device according to another embodiment of the present invention.

FIG. 5 is a sectional view of a conventional rotation angle detection device.

FIG. 6 is a circuit diagram of a conventional rotation angle detection device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Magnetoelectric conversion element 2 Temperature correction circuit 3 Case 3a Case lid 3b Case bottom 4,44 Magnet 4a Magnetization surface 5 Rotating shaft 5a Central shaft 6 Bearing 6a Ball bearing 7a, 7b Connection electrode 8a , 8b Magnetoresistive effect element 9a, 9b Resistance 10 Thermistor 11 Connection terminal 12 Connection point 13 Resistance change part 14a, 14b Temperature-sensitive magnetic body 20, 30, 40 Rotation angle detection device

Claims (5)

[Claims] 1. A rotating shaft rotatably supported, a magnetoelectric conversion element arranged axially of the rotating shaft, and a line connecting the centers of both magnetic poles facing each other, the axis of the rotating shaft And a temperature-sensitive magnetic body disposed close to the magnet, the magnet being aligned with the direction, and the line connecting the centers of the opposing magnetic poles being displaced from the center of the rotation axis. A characteristic rotation angle detection device. 2. The rotation angle detecting device according to claim 1, wherein the magnet is composed of a single unit, and the temperature-sensitive magnetic body is arranged on a side surface or an end surface of the magnet. 3. The rotation angle detecting device according to claim 1, wherein the magnet is composed of a single magnet, and temperature-sensitive magnetic bodies are arranged on the side surface and the end surface of the magnet, respectively. 4. The rotation angle detecting device according to claim 1, wherein the magnet is composed of a plurality of magnets, and the temperature-sensitive magnetic body is arranged on a side surface or an end surface of at least one of the magnets. 5. The rotation angle detecting device according to claim 1, wherein the magnet is composed of a plurality of magnets, and a temperature-sensitive magnetic body is arranged on each of a side surface and an end surface of at least one of the magnets.