JP3496581B2 - Rotation angle detector - Google Patents

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 having improved output characteristics with respect to a rotation angle.

[0002]

2. Description of the Related Art For example, a rotation angle detecting device for detecting the opening of a throttle valve of an internal combustion engine (throttle opening) is
As shown in FIG. 15, on the inner peripheral side of the cylindrical rotor core 11 that rotates integrally with the throttle valve (not shown),
The stator core 12 is coaxially arranged. Two arc-shaped permanent magnets 13 are fixed to the inner peripheral portion of the rotor core 11 so as to face each other with the stator core 12 interposed therebetween. Each of the permanent magnets 13 is radially magnetized so that all the magnetic lines of force inside the magnets are in the radial direction (radial direction). Note that, in FIG. 15, the direction of the magnetic force lines in each component is indicated by an arrow (→). On the other hand, a magnetic flux detection gap portion 14 having a constant width is formed in the central portion of the stator core 12 so as to penetrate in the diametrical direction.
4, a magnetic detection element 15 such as a Hall IC is arranged.

In this configuration, as shown in FIG. 17, the magnetic flux density passing through the magnetic flux detecting gap portion 14 of the stator core 12 (the magnetic detecting element 1) according to the rotation angle of the rotor core 11.
The magnetic flux density linked to 5 changes, and the output of the magnetic detection element 15 changes according to the magnetic flux density. Therefore, from the output of the magnetic detection element 15, the rotation angle of the rotor core 11 (the rotation angle of the throttle valve) is calculated. I'm trying to detect.

[0004]

In the above-mentioned configuration, the output of the magnetic detection element 15 for detecting the rotation angle of the rotor core 11 changes according to the magnetic flux density of the magnetic flux detection gap portion 14, so that the rotation angle of the rotor core 11 changes. Accordingly, if the magnetic flux density of the magnetic flux detection gap portion 14 changes linearly, the output characteristic of the magnetic detection element 15 with respect to the rotation angle becomes linear (straight line), and the rotation angle detection characteristic improves.

However, in the above conventional structure, the permanent magnet 13 is used.
Is radially magnetized, so as shown in FIG.
According to the rotation angle of the rotor core 11, the magnetic flux detection gap portion 1
The range in which the magnetic flux density of 4 changes linearly is only about 80 °. Therefore, if the rotation angle exceeds 80 °,
There is a drawback in that a linear output with respect to the rotation angle cannot be obtained, and the detection accuracy of the rotation angle deteriorates.

Further, in order to uniformly radially magnetize the permanent magnets 13, it is necessary to make the density on the inner peripheral side of the permanent magnets 13 dense and the density on the outer peripheral side coarse, so that the permanent magnets 13 are different due to the density difference. There is also a drawback that the strength of the is easily weakened.

The present invention has been made in view of the above circumstances, and therefore an object thereof is to improve the linearity of the output characteristic with respect to the rotation angle and to improve the detection accuracy of the rotation angle. An object of the present invention is to provide a rotation angle detecting device that can increase the strength of a permanent magnet.

[0008]

In order to achieve the above object, the rotation angle detecting device according to claim 1 of the present invention has a radial gap type structure in which a stator core and a permanent magnet are opposed to each other in a radial direction, and A magnetic circuit is formed by a permanent magnet, a stator core and a rotor core, and a semi-annular or arc-shaped permanent magnet attached to the rotor core is
The magnets are magnetized so that the lines of magnetic force inside the magnet are parallel to each other (parallel magnetization). As described above, when the semi-annular or arc-shaped permanent magnets are magnetized in parallel, the range in which the magnetic flux density of the magnetic flux detection gap portion of the stator core linearly changes according to the rotation angle of the rotor core is conventionally set. It can be expanded more than radial magnetization. As a result, it becomes possible to obtain a linear output with respect to the rotation angle in a wider range than in the past, and it is possible to improve the detection accuracy of the rotation angle. Moreover, in the parallel magnetization, the density of the inner circumference side and the outer circumference side of the permanent magnet can be made uniform, and the strength of the permanent magnet can be increased.
Further, since the stator core and the permanent magnet have a radial gap type configuration in which they are opposed to each other in the radial direction, the coaxial accuracy of the stator core and the permanent magnet is secured, and the radial air gap between them is formed uniformly and small. Therefore, good linearity of the output characteristic of the magnetic detection element hole with respect to the rotation angle can be secured.

In this case, by mounting the permanent magnet in the recess formed in the inner peripheral portion of the rotor core, the air gap between the permanent magnet and the stator core is aligned with the air gap between the rotor core and the stator core. It may be formed uniformly. If you do this, for example,
Even when only one permanent magnet is attached to one side of the rotor core, the air gap can be formed uniformly over the entire outer circumference of the stator core, and good linearity of output characteristics with respect to the rotation angle can be secured. Moreover, 1 permanent magnet
If you do it individually, the cost can be reduced accordingly.

Further, as in claim 3, two permanent magnets may be arranged so as to face each other with the stator core interposed therebetween. With this configuration, compared with the case where only one permanent magnet is attached to one side of the rotor core, the magnetic flux density passing through the magnetic flux detection gap portion of the stator core can be increased and the output of the magnetic detection element can be increased. The detection accuracy of the rotation angle can be improved. Further, if the magnetic flux density to be detected is increased, the amplification factor of the output signal of the magnetic detection element can be reduced accordingly, and the configuration of the signal amplification circuit can be simplified.

Although only one magnetic detection element may be provided, a plurality of magnetic detection elements are arranged in the direction of the magnetic flux passing through the magnetic flux detection gap portion of the stator core or in the direction perpendicular to the magnetic flux detection gap portion. It may be done. By doing so, the magnetic flux densities linked to the plurality of magnetic detection elements can be made substantially the same, so the outputs of the plurality of magnetic detection elements are compared with each other to check whether there is any abnormality. While being able to detect the rotation angle.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION [Embodiment (1)] An embodiment (1) of the present invention will be described below with reference to FIGS. 1 to 8.

First, the overall configuration of the rotation angle detecting device will be described with reference to FIGS. A rotation shaft 22 of an object to be detected such as a throttle valve is rotatably inserted and supported through a bearing 23 in a main body housing 21 of the rotation angle detection device. A cylindrical cup-shaped rotor core 24 is fixed to the tip end (right end) of the rotary shaft 22 by caulking or the like, and a stator core 25 is coaxially arranged on the inner peripheral side of the rotor core 24. Rotor core 24 and stator core 25
Are both made of a magnetic material such as iron.

Only one semi-annular permanent magnet 27 is attached to the inner peripheral portion of the rotor core 24. The permanent magnet 27 is fitted into a concave portion 26 formed in the inner peripheral portion of the rotor core 24 over a substantially half circumference and fixed by adhesion, resin molding, or the like, and an air gap is uniformly formed around the outer circumference of the stator core 25. There is. This permanent magnet 27 is shown in FIG.
As shown in, the magnetic fields are magnetized so that the magnetic lines of force inside the magnet are parallel to each other. When this permanent magnet 27 is attached to the rotor core 24, as shown in FIG. 5B, the magnetic flux of the permanent magnet 27 flows to the rotor core 24 in the state where the stator core 25 is not provided on the inner peripheral side of the rotor core 24, so that the permanent magnet 27 The direction of the magnetic field lines inside the will tilt outward. Further, when the stator core 25 is arranged on the inner peripheral side of the rotor core 24, the magnetic flux of the permanent magnet 27 flows into the stator core 25 as shown in FIG. Becomes
The state is almost parallel.

A plurality of through holes 28 for preventing a short circuit of magnetic flux are formed on the left side surface of the rotor core 24.
Are formed so as to surround (see FIG. 3). The outer peripheral portion of the rotor core 24 is molded with resin 29.

On the other hand, in the central portion of the stator core 25, a magnetic flux detecting gap portion 3 having a constant width for forming a parallel magnetic field is formed.
0 is formed so as to penetrate in the diametrical direction (specifically, the stator core 25 is divided into two so as to form the magnetic flux detection gap portion 30 having a constant width, and the width of the magnetic flux detection gap portion 30 is made by the resin spacer 32. (Regulated), two Hall ICs 31 are arranged in the magnetic flux detection gap portion 30. Each Hall IC 31 is an IC that integrates a Hall element (magnetic detection element) and an amplifier circuit, and outputs a voltage signal corresponding to the magnetic flux density passing through the magnetic flux detection gap section 30 (the magnetic flux density interlinking with the Hall IC 31). Output. Each Hall IC 31 is positioned by a spacer 32 made of resin, and the terminal of each Hall IC 31 is connected to the connector pin 33 through the spacer 32 by welding or the like.
The connector pin 33, the stator core 25, the spacer 3
The connector housing 34 is formed by molding 2 and the like with resin.

An annular recess 35 is formed on the left side surface of the connector housing 34 concentrically with the stator core 25, and the right end edge portion 36 of the main body housing 21 is fixed to the annular recess 35 by press fitting, bonding or the like. The coaxial accuracy of the rotor core 24 and the stator core 25 is ensured.

Next, the layout and connection method of the Hall IC 31 will be described. The two Hall ICs 31 are shown in FIG.
As shown in (a), they are arranged in an overlapping manner in the direction (vertical direction) of the magnetic flux passing through the magnetic flux detection gap portion 30. Or
As shown in FIG. 2B, the two Hall ICs 31 may be arranged side by side in the direction perpendicular to the direction of the magnetic flux passing through the magnetic flux detection gap portion 30. In any case, the position of the Hall element inside the Hall IC 31 is arranged within the range of 0.8 × D with respect to the diameter D of the stator core 25.
As a result, the magnetic flux densities linked to the Hall elements of the two Hall ICs 31 can be made substantially the same.

Further, as shown in FIG. 4A, when two Hall ICs 31 are arranged so as to be overlapped in the direction of the magnetic flux, the output terminals V1 and V2 of each Hall IC 31 and the ground terminal G are arranged.
It is preferable to arrange the two Hall ICs 31 in the same direction so as not to intersect the wirings of the ND and the power supply terminal VC. On the other hand, as shown in FIG. 4B, when the two Hall ICs 31 are arranged side by side in the direction perpendicular to the direction of the magnetic flux, if the two Hall ICs 31 are arranged opposite to each other, the output terminals of each Hall IC 31 may be reversed. It is possible to prevent the wirings of V1, V2, the ground terminal GND, and the power supply terminal VC from intersecting each other.

The Hall IC 31 may have a function of performing output gain adjustment, offset adjustment, temperature characteristic correction with respect to magnetic flux density by electrical trimming, or a self-diagnosis function of disconnection or short circuit.

In the rotation angle detecting device constructed as described above, as shown in FIG. 5 (a), the magnetic circuit has the permanent magnet 2
7 N pole → upper side of stator core 25 → magnetic flux detection gap 30 → lower side of stator core 25 → rotor core 24
→ It is formed by the path of the S pole of the permanent magnet 27. When the rotor core 24 rotates with the rotation of the object to be detected such as the throttle valve, the stator core 2 is rotated according to the rotation angle.
5, the magnetic flux density passing through the magnetic flux detection gap portion 30 (magnetic flux density interlinking with the Hall IC 31) changes, and the output of the Hall IC 31 changes according to this magnetic flux density. A control circuit (not shown) reads the output of the Hall IC 31 and detects the rotation angle of the rotor core 24 (the rotation angle of the detected object). At this time, the outputs V1 and V2 of the two Hall ICs 31
The rotation angle is detected while comparing with each other to check whether there is any abnormality.

In the comparative example shown in FIG. 6, the magnetization of the permanent magnet 27 is changed to the radial magnetization. In this comparative example, as shown in FIG. 8, the magnetic flux detection gap with respect to the rotation angle of the rotor core 24 is changed. The linearity of the magnetic flux density change of the portion 30 deteriorates, the linearity of the output characteristic of the Hall IC 31 deteriorates, and the detection accuracy of the rotation angle decreases.

On the other hand, in the present embodiment (1), since the permanent magnet 27 is magnetized in parallel, as shown in FIG. 7, the magnetic flux density change of the magnetic flux detecting gap portion 30 with respect to the rotation angle of the rotor core 24 is changed. Is improved, and the range of the rotation angle in which the magnetic flux density of the magnetic flux detection gap portion 30 linearly changes according to the rotation angle of the rotor core 24 is about 120 ° or more. As a result, it becomes possible to obtain a linear output with respect to the rotation angle in a wider range than in the past, and it is possible to improve the detection accuracy of the rotation angle. Moreover, the permanent magnet 2
When 7 is magnetized in parallel, the densities of the inner and outer peripheral sides of the permanent magnet 27 can be made uniform, and the strength of the permanent magnet 27 can be increased.

In the present embodiment (1), the permanent magnet 2
7 is attached to the recess 26 formed in the inner peripheral portion of the rotor core 24, the permanent magnet 27 is attached to the rotor core 24.
Although only one is attached to one side of the stator core 25, the air gap around the entire outer circumference of the stator core 25 can be formed uniformly, and good linearity of output characteristics with respect to the rotation angle of the rotor core 24 can be secured. Moreover, the permanent magnet 2
Since only one 7 is used, it is possible to meet the requirements for reduction in the number of parts and cost reduction.

Further, in this embodiment (1), the two Hall ICs 31 are arranged in the magnetic flux detection gap portion 30 in the direction of the magnetic flux or in the direction perpendicular thereto, and the position of the Hall element of the Hall IC 31 is the diameter D of the stator core 25. Since they are arranged so as to be within the range of 0.8 × D, the magnetic flux densities linked to the Hall elements of the two Hall ICs 31 can be made substantially the same, and the outputs of the two Hall ICs 31 can be compared with each other. Then, the rotation angle can be detected while checking whether there is any abnormality, and the reliability of the rotation angle detection device can be improved.

By the way, an axial gap type structure is conceivable in which the permanent magnet is opposed to the stator core in the axial direction (axial direction), and the magnetic flux is allowed to pass in the axial direction between the permanent magnet and the stator core. Therefore, in order to secure good linearity of the output characteristics of the Hall IC with respect to the rotation angle, it is necessary to form the air gap in the thrust direction between the permanent magnet and the stator core uniformly and small. Magnet (rotor core)
It is necessary to precisely control the flatness and parallelism of the facing surfaces of the stator core and the stator core, which increases the cost.

In this regard, in the present embodiment (1), since the stator core 25 and the permanent magnet 27 have a radial gap type structure in which they are opposed to each other in the radial direction, the right end edge portion 36 of the main body housing 21 is an annular shape of the connector housing 34. By the simple method of fixing the rotor core 24 (permanent magnet 27) and the stator core 25 in the concave portion 35, the radial air gap between the rotor core 24 (permanent magnet 27) and the stator core 25 can be made uniform and small. Good linearity of the output characteristics of the Hall IC 31 with respect to the corner can be ensured.

[Embodiment (2)] Next, FIG. 9 and FIG.
The embodiment (2) of the present invention will be described with reference to FIG. However, parts that are substantially the same as in the above embodiment (1) are assigned the same reference numerals and explanations thereof are omitted.

In the present embodiment (2), the rotor core 24 and the permanent magnet 27 are molded with resin to form the rotary lever 37 for connecting with the object to be detected. The rotary lever 37 is molded with the rotor core 24. A resin portion is rotatably fitted and supported on the outer periphery of the stator core 39.
In this case, the mold resin portion on the inner peripheral side of the rotor core 24 functions as a bearing portion (sliding portion) for the stator core 39. Therefore, the magnetic gap on the outer circumference of the stator core 39 with respect to the rotor core 24 and the permanent magnet 27 is ensured by the thickness of the molded resin portion. Rotating lever 37
Is urged in a predetermined rotational direction by the torsion coil spring 41, and is automatically returned to the initial position by the urging force.

An insertion hole 38 is formed at the center of the rotary lever 37.
Is formed, and the insertion hole 38 is inserted into the small diameter portion 40 provided at the left end portion of the stator core 39.
By the stopper plate 43 fixed to the tip of
The rotating lever 37 is prevented from coming off from the stator core 39. A spring washer 42 that restricts the movement of the rotary lever 37 in the thrust direction is sandwiched between the stopper plate 43 and the rotary lever 37.

Further, a magnetic flux detecting gap portion 30 penetrating in the diametrical direction is formed in the central portion of the stator core 39,
As shown in FIG. 10A, this magnetic flux detection gap portion 3
Two Hall ICs 31 are arranged so as to overlap with each other in the direction of the magnetic flux passing through the magnetic flux detection gap portion 30. Alternatively, FIG.
As shown in (b), the two Hall ICs 31 may be arranged side by side in the direction perpendicular to the direction of the magnetic flux passing through the magnetic flux detection gap portion 30. A cylindrical cover portion 44 is integrally formed with the connector housing 34 so as to surround the rotary lever 37 and the rotor core 24.

Also in the present embodiment (2) described above, the permanent magnets 27 are magnetized in parallel as in the above-mentioned embodiment (1). As a result, the range in which the magnetic flux density of the magnetic flux detection gap portion 30 changes linearly according to the rotation angle of the rotor core 24 can be expanded, and a linear output with respect to the rotation angle can be obtained in a wider range than in the past. Therefore, the detection accuracy of the rotation angle can be improved.

[Embodiment (3)] Next, FIGS.
Embodiment (3) of the present invention will be described with reference to FIG. Since this embodiment (3) has many parts in common with the above-mentioned embodiment (1), the substantially same parts as the above-mentioned embodiment (1) are:
The same reference numerals are given and the description is omitted.

In the embodiment (1), only one permanent magnet 27 is attached to one side of the rotor core 24, but in the embodiment (3), as shown in FIGS. Two arc-shaped permanent magnets 45 and 46 are attached to both sides of the stator core 24 so as to face each other. As shown in FIG. 14 (c), the upper permanent magnet 45 is magnetized in parallel so that the outer peripheral side has an S pole and the inner peripheral side has an N pole, and the lower permanent magnet 46 has an outer peripheral side with an N pole. The magnets are parallel magnetized so that the peripheral side becomes the S pole. When these permanent magnets 45 and 46 are attached to the rotor core 24, as shown in FIG.
In the state where the stator core 25 is not provided on the inner peripheral side of 4, the direction of the magnetic force lines inside the upper permanent magnet 45 is inclined outward, and the direction of the magnetic force lines inside the lower permanent magnet 46 is inclined inward. Further, in the state where the stator core 25 is arranged on the inner peripheral side of the rotor core 24, as shown in FIG.
Since the magnetic flux of the upper permanent magnet 45 flows through the stator core 25 to the lower permanent magnet 46, the permanent magnets 45, 46
The inclination of the magnetic lines of force inside becomes smaller and the state becomes almost parallel.

Further, as in the above embodiment (1),
The magnetic flux detection gap section 30 has two Hall ICs 31.
Are arranged so as to overlap in the direction of the magnetic flux [see FIG. 12 (a)], or are arranged side by side in the direction perpendicular to the direction of the magnetic flux [see FIG. 12 (b)].

The conventional example shown in FIG. 15 has two permanent magnets 1.
3 is radially magnetized, but in this conventional example,
As shown in FIG. 17, the range of the rotation angle in which the magnetic flux density of the magnetic flux detection gap portion 14 linearly changes according to the rotation angle of the rotor core 11 is only about 80 °. For this reason,
When the rotation angle exceeds 80 °, a linear output with respect to the rotation angle cannot be obtained and the detection accuracy of the rotation angle deteriorates.

On the other hand, in the present embodiment (3), the permanent magnets 45 and 46 are magnetized in parallel.
As shown in (a), the range of the rotation angle in which the magnetic flux density of the magnetic flux detection gap portion 30 linearly changes according to the rotation angle of the rotor core 24 can be set to about 100 ° (FIG. 12).
(When the circumferential angle θ of the permanent magnets 45 and 46 is about 100 °), it is possible to obtain a linear output with respect to the rotation angle in a wider range than before, and improve the detection accuracy of the rotation angle. You can

Further, when the circumferential angle θ of the permanent magnets 45 and 46 is increased to nearly 180 °, as shown in FIG. 16 (b), the range of the rotation angle in which the magnetic flux density changes linearly with respect to the rotation angle. Can be expanded to about 120 °, and a linear output with respect to the rotation angle can be obtained in a wider range.

According to the experimental results of the present inventors, when the circumferential angle θ of the permanent magnets 45, 46 is set to 90 ° or more, the magnetic flux density of the magnetic flux detecting gap portion 30 changes linearly according to the rotation angle. It was confirmed that the range of rotation angle can be 100 ° or more.

Further, in this embodiment (3), since the two permanent magnets 45 and 46 are arranged so as to sandwich the stator core 25, as compared with the case where only one permanent magnet is attached to one side of the rotor core. The magnetic flux density passing through the magnetic flux detection gap portion 30 of the stator core 25 can be increased to increase the output of the Hall element, and the detection accuracy of the rotation angle can be improved. Moreover, if the magnetic flux density to be detected is increased, the amplification factor of the output signal of the Hall element can be reduced accordingly, and the configuration of the signal amplification circuit can be simplified. As a result, the cost of the Hall IC 31 can be reduced. In addition, one of the permanent magnets 45 and 46
Since the required magnetic flux density can be ensured even if the thickness of each piece is reduced, the outer diameter of the rotor core 24, and thus the outer diameter of the rotation angle detection device, can be reduced by thinning the permanent magnets 45 and 46. It is also possible to convert.

[Embodiment (4)] Next, FIG. 18 and FIG.
Embodiment (4) of the present invention will be described with reference to FIG. Since this embodiment (4) has many parts in common with the above-mentioned embodiment (2), the substantially same parts as the above-mentioned embodiment (2) are:
The same reference numerals are given and the description is omitted.

In the embodiment (2), only one permanent magnet 27 is attached to one side of the rotor core 24, but in the embodiment (4), two permanent magnets 45, 4 which are magnetized in parallel are attached.
6 are attached to both sides of the rotor core 24 so as to face each other with the stator core 39 interposed therebetween. The other structure is the same as that of the embodiment (2). Also in this embodiment (4), the same effect as that of the above-mentioned embodiment (3) in which the two parallel magnetized permanent magnets 45 and 46 are arranged can be obtained.

In each of the embodiments described above, the number of Hall ICs 31 arranged in the magnetic flux detection gap portion 30 is two, but it may be only one. Further, if there is a space in the space, three or more Hall ICs 31 may be arranged in the direction of the magnetic flux or in the direction perpendicular thereto. Further, as a magnetic detection element for detecting the magnetic flux density of the magnetic flux detection gap portion 30, instead of a Hall IC (Hall element),
A magnetic resistance element or the like may be used.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a rotation angle detection device showing an embodiment (1) of the present invention.

2A and 2B are cross-sectional views taken along the line AA of FIG. 1 showing different placement methods of Hall ICs.

FIG. 3 is a sectional view taken along line BB of FIG.

4A and 4B are circuit diagrams for explaining different arrangements and connection methods of Hall ICs, respectively.

5A and 5B are views for explaining the relationship between parallel magnetization and the flow of magnetic flux in the embodiment (1). FIG. 5A is a diagram showing the flow of magnetic flux in the state where all components are assembled, and FIG. The figure which shows the flow of the magnetic flux of the state, (c) the figure which shows the flow of the magnetic flux of the magnet single item state

FIG. 6 illustrates the relationship between radial magnetization and the flow of magnetic flux in a comparative example, showing the flow of magnetic flux,
(A) is a figure which shows the flow of the magnetic flux in the state with all components assembled, (b)
Is a diagram showing the flow of magnetic flux without a stator core,
(C) is a diagram showing the flow of magnetic flux in the state of a single magnet

FIG. 7 is a diagram showing change characteristics of the magnetic flux density of the magnetic flux detection gap portion with respect to the rotation angle of the rotor core in the embodiment (1).

FIG. 8 is a diagram showing a change characteristic of a magnetic flux density of a magnetic flux detection gap portion with respect to a rotation angle of a rotor core in a comparative example.

FIG. 9 is a vertical sectional view of a rotation angle detection device showing an embodiment (2) of the present invention.

10A and 10B are cross-sectional views taken along line CC of FIG. 9 showing different placement methods of Hall ICs.

FIG. 11 is a vertical cross-sectional view of a rotation angle detection device showing an embodiment (3) of the present invention.

12A and 12B are cross-sectional views taken along the line DD of FIG. 11, showing different placement methods of Hall ICs.

13 is a sectional view taken along line EE of FIG.

14A and 14B are views for explaining the relationship between parallel magnetization and the flow of magnetic flux in embodiment (3). FIG. 14A is a diagram showing the flow of magnetic flux in the state where all components are assembled, and FIG. The figure which shows the flow of the magnetic flux of the state, (c) the figure which shows the flow of the magnetic flux of the magnet single item state

FIG. 15 is a view for explaining the relationship between radial magnetization and the flow of magnetic flux in a conventional example, showing the flow of magnetic flux,
(A) is a figure which shows the flow of the magnetic flux in the state with all components assembled, (b)
Is a diagram showing the flow of magnetic flux without a stator core,
(C) is a diagram showing the flow of magnetic flux in the state of a single magnet

16 (a) and 16 (b) are diagrams showing the relationship between the change characteristic of the magnetic flux density of the magnetic flux detection gap portion and the circumferential angle θ of the permanent magnet with respect to the rotation angle of the rotor core in the embodiment (3).

FIG. 17 is a diagram showing a change characteristic of the magnetic flux density of the magnetic flux detection gap portion with respect to the rotation angle of the rotor core in the conventional example.

FIG. 18 is a vertical cross-sectional view of a rotation angle detection device showing an embodiment (4) of the present invention.

19 (a) and 19 (b) are cross-sectional views taken along line F-F of FIG. 18, showing different placement methods of Hall ICs.

[Explanation of symbols]

21 ... Main body housing, 22 ... Rotating shaft, 24 ... Rotor core, 25 ... Stator core, 26 ... Recessed part, 27 ... Permanent magnet, 30 ... Magnetic flux detection gap part, 31 ... Hall IC (magnetic detection element), 37 ... Rotation lever, 39 ... stator core, 41 ... torsion coil spring, 42 ... spring washer, 43 ... stopper plate, 45, 46 ... permanent magnet.

─────────────────────────────────────────────────── ─── Continuation of front page (56) Reference JP-A-11-83422 (JP, A) JP-A-6-249608 (JP, A) JP-A-8-5312 (JP, A) JP-A-5- 203403 (JP, A) JP-A-5-26610 (JP, A) JP-A-56-107119 (JP, A) Special table 11-514747 (JP, A) Special table 2001-526382 (JP, A) International Publication 99/013296 (WO, A1) International publication 98/008060 (WO, A1) German patent application publication 19753776 (DE, A 1) (58) Fields investigated (Int.Cl. ⁷ , DB name) G01B 7 / 30 G01D 5/14

Claims (4)

(57) [Claims] 1. An annular rotor core that rotates according to the rotation of an object to be detected, a stator core that is coaxially arranged on the inner peripheral side of the rotor core, and is attached to the rotor core so as to face the outer peripheral surface of the stator core. And a semi-annular or arc-shaped permanent magnet, and a magnetic flux detection gap portion formed to create a parallel magnetic field inside the stator core, and outputs a signal according to the magnetic flux density passing through the magnetic flux detection gap portion. And a magnetic gap that has a radial gap type structure in which the stator core and the permanent magnet face each other in the radial direction, and detects the rotation angle of the detected object based on the output signal of the magnetic detection element. A rotation angle detecting device, wherein a magnetic circuit is formed by the permanent magnet, the stator core and the rotor core, and the permanent magnet is a magnet. A rotation angle detecting device, characterized in that the lines of magnetic force inside are magnetized so as to be parallel to each other. 2. The permanent magnet is attached to a recess formed in the inner peripheral portion of the rotor core so that the air gap between the permanent magnet and the stator core is aligned with the air gap between the rotor core and the stator core to be uniform. The rotation angle detection device according to claim 1, wherein the rotation angle detection device is formed. 3. The rotation angle detecting device according to claim 1, wherein two permanent magnets are provided, and the two permanent magnets are arranged so as to face each other with the stator core interposed therebetween. . 4. A plurality of the magnetic detecting elements are provided, and the plurality of magnetic detecting elements are arranged in a direction of a magnetic flux passing through the magnetic flux detecting gap portion or in a direction perpendicular thereto. The rotation angle detecting device according to any one of 3 above.