JP2003035561A - Rotational position detector - Google Patents

Abstract

(57) [Problem] To provide an inexpensive rotational position detecting device that can improve the detection sensitivity without increasing the size of a magnetic field generator and that is not easily affected by an external magnetic field. SOLUTION: A magnetic sensor 1 and a rotator 2 having a magnetic field generator 3 and rotating together with a subject are provided, and rotation of the rotator is changed by an output change of the magnetic sensor according to a magnetic field direction from the magnetic field generator. In the rotational position detecting device for detecting a position, the rotating body has a cylindrical shape surrounding the magnetic sensor, and has two protruding portions protruding inside the cylinder and facing each other with the magnetic sensor interposed therebetween, and at least the It consists of a magnetic field generator and a magnetic material. Further, the shape of the cross section orthogonal to the rotation axis of the rotating body on the opposing surface of the protruding portion is a U-shape in which the central portion is depressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotational position detecting device for detecting the rotational position of a rotating body that rotates together with a subject, and more specifically, it outputs an electric signal corresponding to a magnetic field, such as a Hall element or a magnetoresistive element. The present invention relates to a rotational position detecting device including a magnetic sensor that operates.

[0002]

2. Description of the Related Art FIG. 8 shows, for example, Japanese Patent Application Laid-Open No. 8-201106.
2A and 2B show a configuration of a main part of a throttle opening sensor, which is a conventional rotational position detecting device disclosed in Japanese Patent Publication No. JP-A-2003-264, in which (a) is a perspective view and (b) is a plan view. In the figure, 31 is a rotating shaft, 32 is a rotor, 33 is a permanent magnet (magnetic field generator), 3
Reference numeral 4 is a Hall element (magnetic sensor). Rotor 3 that rotates in conjunction with a rotary shaft 31 of a throttle valve (not shown)
2 is provided with a concentric cylindrical permanent magnet 33 magnetized in a direction orthogonal to the rotation shaft 31.
A Hall element 34 for detecting the magnetic field direction of the permanent magnet 33 is disposed in the center of the hollow portion in parallel with the axial direction of the rotor 32. The Hall element 34 is fixed by a housing portion (not shown) of the throttle opening sensor.
As the throttle valve rotates, the permanent magnet 33 rotates around the Hall element 34 to change the magnetic field direction of the Hall element 34 with respect to the magnetically sensitive surface, and an electric signal corresponding to the changed angle θ, that is, the Hall voltage. Is output from the Hall element 34. In such a throttle opening sensor, the Hall voltage output from the Hall element 34 in this manner is processed as necessary, and an electric signal corresponding to the opening of the throttle valve is output.

[0003]

Although the conventional rotational position detecting device is constructed as described above and further improvement in detection sensitivity is required, development of a magnetic field generator which generates a higher magnetic field and higher sensitivity are required. There was a limit to the development of the improved magnetic sensor, and there was no choice but to cope with the magnetic field generator by making it larger or stronger. Further, since the Hall element 34, which is a magnetic sensor, is arranged in the center of the hollow portion of the concentric cylindrical permanent magnet 33, it is not easily affected by the external magnetic field, but in general, a cylindrical permanent magnet is difficult to manufacture and expensive. There was a problem.

The present invention has been made to solve the above-mentioned problems of the conventional ones, and can improve the detection sensitivity without increasing the size of the magnetic field generator.
Moreover, it is an object of the present invention to obtain a rotational position detecting device that is less susceptible to the influence of an external magnetic field at low cost.

[0005]

A rotational position detecting device according to the present invention comprises a magnetic sensor and a rotating body having a magnetic field generating body and rotating together with a subject, and is dependent on a magnetic field direction from the magnetic field generating body. In the rotational position detecting device that detects the rotational position of the rotating body by the change in the output of the magnetic sensor, the rotating body has a tubular shape surrounding the magnetic sensor, and protrudes inside the tube and faces the magnetic sensor. And has at least the above-mentioned magnetic field generator and a magnetic body.

Further, the shape of the cross section orthogonal to the rotation axis of the rotating body on the opposing surface of the projecting portion is a U shape having a hollow central portion.

Further, the magnetic sensor is arranged at a position deviated from the rotation axis of the rotating body, and the shape of the protruding portion or the arrangement of the magnetic field generating body is a surface passing through the rotating shaft of the rotating body and connecting the two protruding portions. It is asymmetric with respect to the plane perpendicular to.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1. 1 is a transverse cross-sectional view showing the configuration of a main part of a rotational position detecting device according to a first embodiment of the present invention. In the figure, 1 is a magnetic sensor,
For example, a Hall element, a magnetic resistance element, a ferromagnetic resistance element or the like is used. Reference numeral 1a denotes a magnetically sensitive surface of the magnetic sensor 1. Two
Is a rotating body that rotates together with a subject (not shown), and has magnetic field generators 3 arranged opposite to each other with the magnetic sensor 1 interposed therebetween. The rotating body 2 has a cylindrical shape (cylindrical shape) that surrounds the magnetic sensor 1 and projects inside the cylinder.
It has a pair of protrusions 20 that face each other across the protrusions. In this embodiment, the protrusions 20 are made of the magnetic field generator 3 and the cylindrical portion is made of the magnetic body 4. The magnetism generator 3 is, for example, a permanent magnet (sintered magnet, bond magnet, or the like) or an electromagnet, and the magnetic body 4 is, for example, a laminate of iron or silicon steel plates. The magnetic body 3 is fixed to the magnetic body 4 with, for example, an adhesive or an adhesive tape made of a glass material. Reference numeral 20a is a facing surface of the protrusion 20.
Reference numeral 5 denotes an auxiliary magnetic body, which is fixed in the vicinity of the magnetic sensor 1 between the magnetic sensor 1 and the magnetic field generator 3 and is fixed together with the magnetic sensor 1 at a position sandwiching the magnetic sensitive surface 1a of the magnetic sensor 1 from the side. There is. As the auxiliary magnetic body 5, for example, a laminate of iron or silicon steel plates is used. Further, the auxiliary magnetic body 5 has a cross-sectional shape such that the central portion is thicker and becomes thinner toward both ends. In the present embodiment, the auxiliary magnetic body 5 is shaped like a cylinder cut along a plane parallel to the central axis thereof. have. 6
Is the magnetic flux.

In such a structure, the rotating body 2 rotates together with the subject, and the rotation changes the angle of the magnetic flux 6 on the magnetically sensitive surface 1a of the magnetic sensor 1 to change the output of the magnetic sensor 1. The rotation angle is detected by utilizing this. Since the magnetic sensor 1 converts only the component of the magnetic flux generated by the magnetic field generator 3 that is perpendicular to the magnetic sensitive surface 1a into an output, the relationship between the rotation angle and the output is a trigonometric function. Therefore, the output of the magnetic sensor 1 is output from, for example, a microcomputer or a DSP (Digital Signal P).
CPU (Central P) such as
(processing unit) and an analog circuit section, and takes in the output angle conversion section, and converts it into a linear function with respect to the angular position to obtain position information.

As described above, in this embodiment, the rotating body 2 has a cylindrical shape that surrounds the magnetic sensor 1, and has the protruding portions 20 that protrude inside the cylinder and face each other with the magnetic sensor 1 interposed therebetween. Since at least a part (all in the present embodiment) of the magnetic field generator 20 is composed of the magnetic field generator 3 and the cylindrical part is composed of the magnetic body 4, the protrusion 20 enhances the density of the magnetic flux 6 at the position where the magnetic sensor 1 is located. Can, magnetic field generator 3
The detection sensitivity can be improved without increasing the size. Further, since the magnetic sensor 1 is surrounded by the cylindrical magnetic body 4, it is less susceptible to the external magnetic field, and compared with the case where the cylindrical permanent magnet 33 is used as in the conventional rotational position detecting device, The material cost is low and it is easy to manufacture.

In the present embodiment, the magnetic sensor 1 is provided between the magnetic sensor 1 and the magnetic field generator 3 in the vicinity of the magnetic sensor 1.
Is provided so as to sandwich the magnetically sensitive surface 1a from the side, and the auxiliary magnetic body 5 having a shape in which the central portion is thick and becomes thinner toward both ends is provided between both poles of the magnetic field generator 3, particularly near the magnetic sensor 1. By changing the path of the magnetic flux 6 to change the vertical component of the amount of magnetic flux reaching the magnetic sensitive surface 1a of the magnetic sensor 1, that is, the magnetic flux 6 from the magnetic field generator 3 is assisted in the vicinity of the magnetic sensor 1. By bending so as to pass through the magnetic body 5, the vertical component of the magnetic flux entering the magnetically sensitive surface 1a of the magnetic sensor is reduced near the extreme value of the trigonometric function, and the relationship between the rotation angle of the rotating body 2 and the output of the magnetic sensor 1 is reduced. Can be approximated from a curvilinear trigonometric function to a more linear function.

It should be noted that the installation position and detailed shape of the auxiliary magnetic body 5 are such that, when the rotating body 2 rotates, the output of the magnetic sensor 1 is 1 with respect to the rotation angle position by the magnetic field calculation.
It was determined by designing to be the next function. By designing in this way, the output angle conversion unit is not required, the load on the analog circuit unit and CPU that are easily affected by temperature can be reduced, and the cost of the entire device can be reduced.

Although the figure shows the case where the magnetic body 4 is cylindrical, it is not limited to a circle and may be an ellipse or a polygonal cylinder.

It should be noted that the auxiliary magnetic body 5 is not always necessary, and in this case as well, the density of the magnetic flux at the portion where the magnetic sensor is located can be increased, and as a result, the detection sensitivity can be improved without increasing the size of the magnetic field generator. It is possible to obtain the rotational position detecting device that can be improved and is less susceptible to the influence of the external magnetic field at low cost.

Embodiment 2. FIG. 2 is a transverse cross-sectional view showing the configuration of the main part of the rotational position detecting device according to the second embodiment of the present invention. In the first embodiment, the case where the entire protrusion 20 is formed of the magnetic field generator 3 has been described, but in the present embodiment, a part of the protrusion 20 (the tip in the present embodiment) is a magnetic field. It is formed of the generator 3, and the remaining portion including the tubular portion is formed of the magnetic body 4. The magnetic field generator 3 is fixed to the magnetic body 4 with, for example, an adhesive or an adhesive tape made of a glass material. Even with such a configuration, the same effect as in the case of the first embodiment can be obtained.

Incidentally, the auxiliary magnetic body 5 is not always necessary, and in this case as well, the density of the magnetic flux at the site where the magnetic sensor is located can be increased, and as a result, the detection sensitivity can be improved without increasing the size of the magnetic field generator. It is possible to obtain the rotational position detecting device that can be improved and is less susceptible to the influence of the external magnetic field at low cost.

Embodiment 3. FIG. 3 is a transverse sectional view showing the configuration of the main part of a rotational position detecting device according to a third embodiment of the present invention. In the second embodiment described above, the case where the tip of the protrusion 20 is formed of the magnetic field generator 3 has been described, but in the present embodiment, the root of the protrusion 20 is formed of the magnetic field generator 3.
Such a rotating body 2 has a space provided in the magnetic body 4,
As the magnetic field generator 3, for example, a permanent magnet is embedded,
It is manufactured by injection-molding a bond magnet and then magnetizing it. By thus embedding the magnetic field generator 3 inside the magnetic body 4, the magnetic body 4 and the magnetic field generator 3 can be easily fixed to each other, and a rotational position detection device that can withstand high-speed rotation can be obtained.

Incidentally, it is preferable that the region 20b of the magnetic body 4 between the end of the magnetic field generator 3 and the void in the cylinder is as narrow as possible so that the leakage magnetic flux is small.

Further, in the above-mentioned first and second embodiments, the auxiliary magnetic body 5 has a cross-sectional shape such that the central portion is thick and becomes thinner toward both ends, such as a column cut by a plane parallel to its central axis. However, in the present embodiment, the auxiliary magnetic body 4 has a crescent shape, which is one of the cross-sectional shapes in which the central portion is thick and becomes thinner toward both ends. . Also in this case, the same effects as those in the first and second embodiments can be obtained.

The auxiliary magnetic body 5 is not always necessary, and in this case as well, the density of the magnetic flux at the position where the magnetic sensor is located can be increased, so that the detection sensitivity can be improved without increasing the size of the magnetic field generator. It is possible to obtain the rotational position detecting device that can be improved and is less susceptible to the influence of the external magnetic field at low cost.

Fourth Embodiment FIG. 4 is a transverse sectional view showing the configuration of the main part of a rotational position detecting device according to the fourth embodiment of the present invention. In the figure, O is the rotation center of the rotating body 2, that is, the rotation axis. In any of the first to third embodiments, the magnetic sensor 1 is arranged at the rotation center (rotation axis) of the rotating body 2,
Moreover, the case where the shape of the protrusion 20 and the arrangement of the magnetic field generator 3 are symmetric with respect to a plane that passes through the rotation axis of the rotating body 2 and is perpendicular to the surface connecting the two protrusions 20 has been described. In the embodiment, as shown in FIG. 4, the magnetic sensor 1 is arranged at a position deviated from the rotation axis O of the rotating body 2, and the shape of the protrusion 20 and the arrangement of the magnetic field generating body 3 are different from each other. It is asymmetric with respect to a plane that passes through and is perpendicular to the plane connecting the two protrusions.

In the first to third embodiments described above, for example, as shown in FIGS. 1 and 2, the distribution of the magnetic flux 6 between the two poles of the magnetic field generator 3 is symmetrical with respect to the plane passing through the rotation axis of the rotor 2. However, in the present embodiment, the distribution of the magnetic flux 6 between the two poles of the magnetic field generator 3 is asymmetric with respect to the plane passing through the rotation axis O of the rotating body 2, and as shown in FIG. Position of the magnetic sensor 1 and the protruding portion 2 so that the distribution of the magnetic flux 6 of
By designing the shape of 0 and the arrangement of the magnetic field generator 3, it is possible to detect 360 degrees from the change of the polarity (±) of the magnetic flux sensed by the magnetic sensor 1 when rotated by 180 degrees and the change amount with respect to the angle of the magnetic flux. It will be possible.

Although FIG. 4 shows a case where both the shape of the protrusion 20 and the arrangement of the magnetic field generator 3 are asymmetric with respect to the plane passing through the rotation axis O of the rotor 2, the shape of the protrusion 20 is shown. And only one of the arrangements of the magnetic field generator 3 is the rotor 2
Of the magnetic field generator 3 may be asymmetric with respect to the plane passing through the rotation axis O of the magnetic field generator 3. , So that the distribution of the magnetic flux 6 between the two poles has a fan shape.
By designing the position and the shape of the protrusion 20 or the position of the magnetic sensor 1 and the arrangement of the magnetic field generator 3, the same effect as in the case of FIG. 4 can be obtained.

Although FIG. 4 shows the case where the auxiliary magnetic body is not provided, the auxiliary magnetic body may be provided as in the first to third embodiments. In this case, the output magnetic Linearity is further improved.

Embodiment 5. FIG. 5 is a transverse sectional view showing the configuration of the main part of a rotational position detecting device according to a fifth embodiment of the present invention. In any of the first to third embodiments, the magnetic sensor 1 is arranged at the rotation center (rotation axis) of the rotating body 2, and
The case where the two protrusions 20 and the magnetic field generator 3 are arranged at an angle of 180 degrees with respect to the rotation center O of the rotating body 2 has been described, but in the present embodiment, as shown in FIG.
The two protrusions 20 and the magnetic field generator 3 are arranged at a position of 120 degrees with respect to the rotation center O of the rotating body 2, and the magnetic sensor 1 is arranged on an arc connecting the two protrusions 20 (in FIG. 2 is arranged at the rotation center O).

In the present embodiment, as shown in FIG.
By designing the position of the magnetic sensor 1, the shape of the protruding portion 20 and the arrangement of the magnetic field generator 3 so that the distribution of the magnetic flux 6 between both poles becomes an arc shape, the detectable angular range can be widened.

Although FIG. 5 shows the case where the protrusion 20 and the magnetic field generator 3 are arranged at an angle of 120 degrees with respect to the rotation center O of the rotating body 2, the angle is not always 12 degrees.
It does not need to be 0 degree, and may be appropriately designed depending on the magnetic field generated by the magnetic field generator 3. Further, only the protrusions 20 are arranged at an angle that is not 180 degrees with respect to the rotation center O of the rotating body 2, and the magnetic field generator 3 is arranged so that the magnetic flux is generated more efficiently than the protrusions 20 inside the magnetic body 4. In this case as well, the position of the magnetic sensor 1 and the shape of the protruding portion 20, or the position of the magnetic sensor 1 and the magnetic field generator 3 are set so that the distribution of the magnetic flux 6 between the two poles is also an arc shape. By designing the arrangement of, the same effect as in the case of FIG. 5 can be obtained. Furthermore, in FIG. 5, when the shapes of the two protrusions 20 and the arrangement of the magnetic field generators 3 are symmetrical with respect to a plane that passes through the rotation axis of the rotating body 2 and is perpendicular to the plane connecting the two protrusions 20. However, even if the shape of the two protrusions 20 or the arrangement of the magnetic field generators 3 is asymmetric with respect to a plane that passes through the rotation axis O of the rotating body 2 and is perpendicular to the surface connecting the two protrusions 20. Good.

Further, the magnetic sensor 1 does not necessarily have to be near the rotation center O of the rotating body 2, and the vertical component of the arc-shaped magnetic flux that enters the magnetic sensitive surface 1a of the magnetic sensor with respect to the rotation angle. If the linear arrangement is possible, the effect of improving the linearity of the output can be obtained.

Sixth Embodiment FIG. 6 is a transverse sectional view showing the configuration of the main part of a rotational position detecting device according to a sixth embodiment of the present invention. In any of the above second to fifth embodiments, the protruding portion 20 is used.
In the present embodiment, the shape of the cross section orthogonal to the rotation axis of the rotating body 2 in the facing surface 20a is a U shape with a depressed central portion.

In this way, by making the cross section of the facing surface 20a of the protruding portion 20 orthogonal to the rotation axis O of the rotating body 2 into a U-shape with the central portion depressed, the magnetic field generator 3 is separated from the magnetic body. Since the direction of the magnetic flux emitted to the air layer can be finely adjusted via 4 and the amount of the vertical component of the magnetic flux reaching the magnetically sensitive surface 1a of the magnetic sensor can be changed, the rotation angle of the rotating body 2 and the magnetic field can be changed. The relationship with the output of the sensor 1 can be approximated from a curved trigonometric function to a more linear function.

The detailed shape of the facing surface 20a of the protruding portion 20 is determined by the magnetic field calculation when the rotating body 2 rotates.
It was determined by designing the output of the magnetic sensor 1 to be a linear function with respect to the rotational angle position. By designing in this way, the output angle conversion unit becomes unnecessary,
It is possible to reduce the load on the analog circuit section and the CPU that are easily affected by temperature, and reduce the cost of the entire apparatus.

In the case of the first embodiment shown in FIG. 1 as well, the shape of the cross section of the facing surface 20a of the projecting portion 20 orthogonal to the rotation axis of the rotating body 2 is a U-shape having a depressed central portion. Therefore, similarly, the relationship between the rotation angle of the rotating body 2 and the output of the magnetic sensor 1 can be made closer to a linear function from a curvilinear trigonometric function.

Embodiment 7. FIG. 7 is a transverse sectional view showing the configuration of the main part of a rotational position detecting device according to a seventh embodiment of the present invention. In any of the first to sixth embodiments, the protrusion 20
, At least a part of which is the magnetic field generator 3,
Although the case where the magnetic field generator 3 is arranged in the vicinity of the projecting portion 20 is shown, it may be arranged in the cylindrical portion of the rotating body 2 as shown in FIG. Is obtained.

[0034]

As described above, according to the present invention, the magnetic sensor includes the magnetic sensor and the rotating body having the magnetic field generator and rotating together with the subject, and the magnetic sensor according to the magnetic field direction from the magnetic field generator. In the rotational position detecting device that detects the rotational position of the rotating body by the change in the output of the rotating body, the rotating body has a cylindrical shape surrounding the magnetic sensor, and the rotating body protrudes inside the cylinder and faces each other with the magnetic sensor interposed therebetween. Since it has a protrusion and is composed of at least the magnetic field generator and the magnetic body, it is possible to increase the density of the magnetic flux at the position where the magnetic sensor is located. As a result, the detection sensitivity is improved without increasing the size of the magnetic field generator. It is possible to obtain the rotation position detecting device that can be realized and is less susceptible to the influence of the external magnetic field at low cost.

Further, since the shape of the cross section orthogonal to the rotation axis of the rotating body on the facing surface of the protruding portion is U-shaped with the central portion depressed, the output characteristic of the magnetic sensor is linear with respect to the rotation angle of the rotating body. It is possible to improve the sex.

Further, the magnetic sensor is arranged at a position deviated from the rotation axis of the rotating body, and the shape of the protruding portion or the arrangement of the magnetic field generator is such a surface that passes through the rotating shaft of the rotating body and connects the two protruding portions. Since it is asymmetric with respect to the plane perpendicular to, it is possible to make the detection angle of the rotating body 360 degrees.

[Brief description of drawings]

FIG. 1 is a transverse cross-sectional view showing a configuration of a main part of a rotational position detection device according to a first embodiment of the present invention.

FIG. 2 is a transverse cross-sectional view showing the configuration of a main part of a rotational position detecting device according to a second embodiment of the present invention.

FIG. 3 is a transverse cross-sectional view showing a configuration of a main part of a rotation position detecting device according to a third embodiment of the present invention.

FIG. 4 is a cross-sectional view showing the configuration of the main part of a rotational position detecting device according to a fourth embodiment of the present invention.

FIG. 5 is a transverse cross-sectional view showing the configuration of the main part of a rotational position detection device according to a fifth embodiment of the present invention.

FIG. 6 is a transverse cross-sectional view showing the configuration of the main part of a rotational position detection device according to a sixth embodiment of the present invention.

FIG. 7 is a cross-sectional view showing the configuration of the main parts of a rotational position detecting device according to a seventh embodiment of the present invention.

8A and 8B show a configuration of a main part of a conventional rotational position detecting device, in which FIG. 8A is a perspective view and FIG. 8B is a plan view.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Magnetic sensor, 1a Magnetic sensitive surface of magnetic sensor, 2 Rotating body, 20 Projection part, 20a Opposite surface of projection part, 3 Magnetic field generator, 4 Magnetic body, 5 Auxiliary magnetic body, 6 Magnetic flux, 31
Rotating shaft, 32 rotor, 33 permanent magnet (magnetic field generator), 34 Hall element (magnetic sensor).

Continued front page    (72) Inventor Toshiyuki Yoshizawa             2-3 2-3 Marunouchi, Chiyoda-ku, Tokyo             Inside Ryo Electric Co., Ltd. F-term (reference) 2F063 AA35 BA06 CA34 DA05 GA52                       KA01                 2F077 CC02 JJ01 JJ08 JJ09 JJ23                       VV02

Claims (3)

[Claims] 1. A magnetic sensor and a rotating body having a magnetic field generator and rotating together with a subject, wherein a rotational position of the rotating body is determined by a change in output of the magnetic sensor depending on a magnetic field direction from the magnetic field generator. In the rotational position detecting device for detecting, the rotating body is a tubular shape surrounding the magnetic sensor,
A rotational position detecting device having two projecting portions that project inside a cylinder and face each other across the magnetic sensor, and that is composed of at least the magnetic field generator and a magnetic body. 2. The rotational position detecting device according to claim 1, wherein a shape of a cross section of the surface facing the projection portion, which is orthogonal to the rotation axis of the rotating body, is a U shape having a depressed central portion. 3. A magnetic sensor is arranged at a position deviated from the rotation axis of the rotating body, and the shape of the protrusion or the arrangement of the magnetic field generator passes through the rotation axis of the rotating body and connects the two protrusions. The rotational position detecting device according to claim 1, wherein the rotational position detecting device is asymmetric with respect to a plane perpendicular to the plane.