JP2000097607A - Rotation angle detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve miniaturization as a whole by guiding a magnetic flux in yokes to a signal output means to enhance the detection sensitivity of rotation angle while curtailing the number of parts. SOLUTION: First and second yokes 8 and 9 are composed of magnetic pole piece parts 8A and 9A formed being curved in a circular arc and overhang parts 8B and 9B. The first and second yokes 8 and 9 face each other in the diametrical direction sandwiching a magnet 7 and first and second Hall elements 13 and 14 are disposed between the overhang parts 8B and 9B. The height dimensions H1 and H2 of the yokes 8 and 9 are set 2-10 times the height dimension T of the magnet 7.

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 suitably used for detecting, for example, a rotation angle of a rotation shaft, and more particularly to a throttle valve opening and an accelerator pedal opening of an automobile engine. The present invention relates to a rotation angle detecting device used for detecting a rotation angle.

[0002]

2. Description of the Related Art Generally, a turning angle detecting device is widely used for detecting a throttle valve opening, an accelerator pedal opening, and the like of an automobile engine. Therefore, a case in which the opening angle of the throttle valve is detected by the rotation angle detection device will be described as an example.

[0003] In an automobile engine or the like provided with an electronically controlled fuel injection device, a throttle valve is provided in the middle of an intake passage of the engine, and the opening of the throttle valve is detected by a rotation angle detecting device. The signal from the rotation angle detecting device is output to the control unit as a signal corresponding to the intake air amount of the engine, and the control unit calculates the fuel injection amount according to the intake air amount. As a rotation angle detecting device used for such an automobile engine or the like, a non-contact type using a magnet, a yoke, or the like is known (for example, Japanese Patent Application Laid-Open Nos. 9-189508 and 9-189509).
No.).

[0004] Here, the prior art rotation angle detecting device includes a magnet provided on a rotation shaft that rotates according to the opening degree of a throttle valve, and surrounds the circumference of the magnet over substantially the entire circumference. It is composed of three or more yokes and a plurality of Hall elements disposed between the yokes.

[0005] In the conventional rotation angle detecting device,
A plurality of magnetic circuits are formed by a magnet and three or more yokes, and a Hall element is provided independently for each magnetic circuit. Thus, the magnetic flux densities of the plurality of magnetic circuits are detected by the plurality of Hall elements, and the rotation angle of the rotation shaft, that is, the opening degree of the throttle valve is detected by using signals from the Hall elements.

[0006]

However, in the above-described rotation angle detecting device according to the prior art, since the configuration is such that three or more yokes surround the entire circumference of the magnet, the yoke is provided between the yokes. There is a problem that a leakage magnetic flux in the circumferential direction is generated, which adversely affects the detection signal of the rotation angle.

Further, since three or more yokes are disposed in the casing, the rotation angle detecting device is increased in size as a whole, and the number of parts is increased, so that the manufacturing cost is increased.

The present invention has been made in view of the above-mentioned problems of the prior art. The present invention reduces the leakage magnetic flux, increases the detection sensitivity of the rotation angle, and reduces the number of parts to reduce the size of the whole. It is an object of the present invention to provide a rotation angle detecting device.

[0009]

According to a first aspect of the present invention, there is provided a rotation angle detecting apparatus, comprising: a rotatably provided magnet; A first and a second yoke formed by overlapping first and second overhang portions extending radially inward from opposed first and second pole piece portions on the center of rotation of the magnet; A signal output means provided between the first and second overhang portions constituting the first and second yokes, and for outputting a signal corresponding to an area of the magnet and the first and second yokes facing each other; And the height of the first and second yokes in the axial direction is set to be 2 to 10 times the height of the magnet.

With this configuration, the facing area between the magnet and the first and second magnetic pole pieces changes according to the rotation angle. Since the signal output means outputs a signal corresponding to the area of the magnet and the first and second yokes facing each other, the rotation angle can be detected by using the signal output from the signal output means.

Since the first and second yokes have a height in the axial direction that is 2 to 10 times the height of the magnet, the magnet can be securely attached to the first and second yokes. Can be opposed. Thereby, the magnetic flux from the magnet can be guided into the first and second yokes, and the magnetic flux from the magnet can be prevented from leaking to the outside.

Further, the invention of claim 2 provides the first and second inventions.
A magnetic flux blocking portion for blocking a magnetic flux directed in the circumferential direction between the first and second magnetic pole pieces is provided between the magnetic pole pieces.

[0013] Thus, the magnetic flux blocking unit suppresses the magnetic flux from the magnet from directly circling in the circumferential direction. Therefore, the leakage magnetic flux can be reduced, and more magnetic flux from the magnet can be guided to the signal output means.

According to a third aspect of the present invention, between the first and second overhang portions and the magnet, a magnetic flux from the magnet to the signal output means is cut off.
mm gap in the axial direction.

Thus, the first and second overhang portions are separated from the magnet by the axial gap, and the magnetic flux from the magnet reaches the first and second overhang portions without passing through the yoke. Can be prevented. For this reason, it is possible to prevent the short-circuit magnetic flux reaching the first and second overhang portions from the magnet without passing through the yoke from being detected by the signal output means disposed between the first and second overhang portions. it can.

Further, the invention of claim 4 is the first or second invention.
A radial gap of 2 to 5 mm is provided between the magnetic pole piece and the magnet.

With this configuration, it is possible to reduce the entry of the magnetic flux from the magnet into the yoke from the circumferential ends of the first and second pole pieces due to the radial gap. Thereby, a magnetic flux corresponding to the facing area between the magnet and the first and second pole piece portions can be guided into the yoke.

Further, according to a fifth aspect of the present invention, the magnet is formed such that both end surfaces having different magnetic poles with respect to the center of rotation of the magnet are formed as convex circular arc surfaces, and the first and second magnetic pole pieces are formed. The portion is formed with a concave arc surface portion coaxially opposed to each convex arc surface portion with respect to the rotation center of the magnet.

With this configuration, the facing area between the concave arc surface of the first pole piece and the convex arc surface of the magnet is reduced by the area of the concave arc surface of the second pole piece and the convex arc surface of the magnet. The opposing areas can be made substantially equal, the changes in the opposing areas of the first and second magnetic pole pieces with respect to the magnet can be made substantially equal to each other, and the magnetic flux density in the yoke can be changed more greatly with respect to the rotation angle.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a rotation angle detecting device according to the present invention will be described below in detail with reference to FIGS.

In FIG. 1, reference numeral 1 denotes a casing forming the outer shape of the rotation angle detecting device. The casing 1 has a cylindrical portion 1A extending in the axial direction, and a cover 18 provided in the axial direction of the cylindrical portion 1A and described later. A partition wall 1B defining an accommodation chamber A in the cylindrical portion 1A, and a cylindrical protrusion 1C protruding axially upward from the partition wall 1B to position a yoke support cylinder 3 described later.
And a cylindrical bearing holding portion 1D projecting axially downward from the partition wall portion 1B and having an inner peripheral side communicating with the accommodation chamber A, and projecting radially outward from the outer peripheral side of the cylindrical portion 1A. And two connector sections 1E, 1E. The lower portion of the partition wall 1B includes the cylindrical portion 1A and the bearing holding portion 1.
A space between the spring chamber D and a spring chamber B for a return spring 17 to be described later.

A plurality of pin terminals 2 (only one is shown) extending from the connector portion 1E into the housing chamber A are embedded in the casing 1, and, for example, 100
A notch (not shown) is provided over an angle range of about °, and the notch regulates a rotation range of a lever 16 described later.

Reference numeral 3 denotes a yoke support cylinder positioned on the partition wall 1B of the casing 1 by a cylindrical projection 1C. The yoke support cylinder 3 is formed of a nonmagnetic material such as a resin material into a closed cylindrical shape, which will be described later. The first and second yokes 8 and 9 are integrally held by means such as a resin mold. The yoke support cylinder 3 is removably fitted together with the first and second yokes 8 and 9 in the cylindrical projection 1C of the casing 1, and the first and second yokes 8, 9 for the magnet 7 described later. Is positioned.

Reference numeral 4 denotes a rotating shaft rotatably provided in the casing 1, and the rotating shaft 4 uses a bearing 5 to support the bearing holder 1.
D, and the distal end side of the rotating shaft 4 is a bearing holding portion 1
A rotating plate 6, which protrudes from the inside of the housing D toward the housing chamber A and is described later, is integrally formed. The base end side of the rotating shaft 4 projects axially downward from the bearing holding portion 1D, and a lever 16 is attached thereto.

Reference numeral 6 denotes a rotating plate integrally formed on the distal end side of the rotating shaft 4. The rotating plate 6 is formed in a substantially disc shape, and a magnet 7 described later is formed on the rotating plate 6. It is fixed.

Reference numeral 7 denotes a magnet fixed on the rotating plate 6 with an adhesive or the like. The magnet 7 is formed in a rectangular or oval shape having magnetic poles on both sides in the length direction.
As shown in FIGS. 3 to 5, the magnet 7 has convex arcuate surfaces 7A and 7B at both ends in the length direction, and parallel surfaces 7C and 7D between the convex arcuate surfaces 7A and 7B.

Here, the convex arcuate surface portion 7A of the magnet 7
7B is, for example, 70 ° -1 ° with respect to the rotation center O1-O1.
It is formed with an angle α1 of 10 °, preferably 90 °. The angle α1 of the convex arc-shaped surface portions 7A, 7B is set to a value substantially equal to the angle α2 of the pole piece portions 8A, 9A of the yokes 8, 9 described later. Also, the magnet 7
Is formed with a height T in the axial direction of the rotating shaft 4 as shown in FIG.
It is set to 3 mm, preferably about 2 mm. The magnet 7 is disposed at the center of the pole pieces 8A and 9A in the height direction (axial direction).

The magnet 7 is formed of a material having a magnetic property of a maximum energy product of 20 × 10 ⁶ Gauss Oersted or less (for example, a rare-earth bonded magnet of Nd—Fe—Co or Sm—Co).

Numeral 8 designates a casing 1 by a yoke support cylinder 3.
The first yoke 8 provided in the first yoke 8
For example, it is formed of a magnetic material having a coercive force of 1 Oe or less, such as electromagnetic pure iron (SUYB, SUYP), Fe—Ni alloy, etc., and guides the magnetic flux by the magnet 7 to the Hall elements 13 and 14 described later. .

As shown in FIGS. 3 to 5, the yoke 8 has a curved plate-shaped first magnetic pole piece 8A opposed to the convex arcuate surface 7A of the magnet 7 with a constant radial gap Gr. A first overhang portion 8B which is formed by bending inward in the radial direction from the first pole piece 8A and extends in a plate shape so as to straddle the magnet 7 from above.

The first pole piece 8A is formed in an arc shape with a constant radius of curvature with respect to the center of rotation O1 -O1 of the magnet 7, and the inner peripheral side thereof has a center of rotation O1 of the magnet 7. Convex arc surfaces 7A, 7B with respect to -O1
And a concave arc-shaped surface portion 8A1 which is coaxially opposed. The first pole piece 8A has an angle α of, for example, 70 ° to 110 °, preferably 90 ° with respect to the rotation center O1 -O1.
Extending with two.

On the other hand, a radial gap Gr between the pole piece 8A of the yoke 8 and the convex arc-shaped surfaces 7A and 7B of the magnet 7 is provided.
Is set, for example, to 2 to 5 mm, preferably about 3 mm. The pole piece 8A has a height H1 in the axial direction of the rotating shaft 4. The height H1 is set to, for example, about 6 mm as a value of about 2 to 10 times the height T of the magnet 7 as shown in FIG.

The overhang portion 8B of the yoke 8
The magnet 7 faces the magnet 7 with a certain axial gap Gs in the axial direction, and partially covers the magnet 7 from above. The axial gap Gs between the overhang portion 8B and the magnet 7 is set to, for example, 1.5 to 10 mm, and preferably about 3 mm.

Numeral 9 denotes a second yoke provided in the casing 1 and formed of a magnetic material substantially similar to the first yoke 8. The second yoke 9 is a magnet as shown in FIGS. A magnetic circuit is formed by radially opposing the first yoke 8 with the intermediary 7 interposed therebetween, and the magnetic flux generated by the magnet 7 is guided to Hall elements 13 and 14 to be described later. Similarly to the yoke 8, the yoke 9 has a second magnetic pole piece 9A opposed to the convex arcuate surfaces 7A and 7B of the magnet 7 while keeping a constant radial gap Gr, and a second magnetic pole piece 9A. And a second overhang portion 9B which is formed by bending inward in the radial direction and extends in a plate shape so as to straddle the magnet 7 from above.

The second pole piece 9A is radially opposed to the first pole piece 8A with the magnet 7 interposed therebetween. The second pole piece 9A is formed in a circular arc shape with a constant radius of curvature with respect to the center of rotation O1 -O1 of the magnet 7, and the inner peripheral side thereof is connected to the center of rotation O1 -O1 of the magnet 7. On the other hand, a concave arc surface portion 9A1 coaxially opposed to the convex arc surface portions 7A and 7B. The second pole piece 9A extends at an angle .alpha.2 substantially equal to the first pole piece 8A with respect to the center of rotation O1 -O1.

On the other hand, the second overhang portion 9B has an inner peripheral end extending to a position exceeding the rotation center O1-O1 of the magnet 7, and has a constant gap 10 of about 1.7 mm, for example.
And partially overlap with the first overhang portion 8B. Then, the first and second overhang portions 8B,
9B, hall elements 13 and 14 described later are provided. Thereby, the first and second overhang portions 8 are formed.
B and 9B are configured to sandwich the Hall elements 13 and 14 from above and below.

The distance between the magnetic pole piece 9A of the yoke 9 and the convex arc surface portions 7A, 7B of the magnet 7 is determined by the radial gap Gr between the magnetic pole piece 8A of the yoke 8 and the convex arc surface portions 7A, 7B of the magnet 7. As a value approximately equal to, for example, 2 to 5
mm, preferably about 3 mm.

As shown in FIG. 6, the second pole piece 9A has a height H2 in the axial direction of the rotary shaft 4, and the height H2 is equal to the first pole piece. The height is set to be larger than the height H1 of the portion 8A by the dimension of the gap 10. Then, the height dimension H2 of the pole piece 9A
Is set to a value of about 2 to 10 times the height dimension T of the magnet 7, for example, about 7.7 mm.

Here, as shown in FIG. 7, the rotation angle ± θ of the magnet 7 is such that the central portion of the convex arc-shaped surface portion 7A is an intermediate point between the first magnetic pole piece portion 8A and the second magnetic pole piece portion 9A. When the magnet 7 is turned to the right, the magnet 7 is turned to the right. At this time, the magnet 7 (rotating shaft 4)
Is within a range of ± 45 °, and the rotation angle θ is +4.
5 ° corresponds to the maximum opening of the throttle valve (full throttle).

Reference numerals 11 and 11 denote first and second pole piece portions 8A,
9A, the magnetic flux blocking portions 11 are radially opposed to each other with the magnet 7 interposed therebetween, as shown in FIG. 3, and the first and second magnetic pole piece portions 8A, It extends in the circumferential direction between 9A and constitutes a part of the yoke support cylinder 3.
The magnetic flux interrupting section 11 has an angle α3 of, for example, 50 ° to 130 °, preferably 90 ° with respect to the rotation center O1 -O1. In particular, it is preferable that the angle α3 is set to a value substantially equal to the angle α1 of the convex arc-shaped surface portions 7A and 7B of the magnet 7.

Reference numeral 12 denotes a flexible substrate formed of a resin material or the like, and the flexible substrate 12 is accommodated in the accommodation chamber A with a part thereof being bent substantially in a V shape as shown in FIG. . Hall elements 13 and 14 are attached to one end of the flexible substrate 12, and the gap 10
It is arranged in. The other end of the flexible substrate 12 is connected to the pin terminal 2 by means such as soldering.

Reference numerals 13 and 14 denote first and second signal output means.
In the second Hall element, the Hall elements 13 and 14 are attached to the flexible substrate 12, and are arranged at different positions in the gap 10 between the first and second overhang portions 8B and 9B. The magnetic detection directions of the Hall elements 13 and 14 are parallel to the axial direction of the rotating shaft 4 and perpendicular to the magnetic pole lines of the magnet 7. The Hall elements 13 and 14 include a magnet 7, a first yoke 8,
The first and second detection signals are output in proportion to the magnetic flux density passing through the magnetic circuit including the second yoke 9.

The Hall elements 13 and 14 are connected to a circuit component 15 described later. Therefore, for example, the first and second detection signals can be compared by the circuit component 15 to determine whether or not a failure has occurred in the Hall elements 13 and 14. Further, for example, the circuit component 15 can calculate the average value of the first and second detection signals, and can detect the rotation angle θ more accurately.

Reference numerals 15 and 15 denote circuit components mounted on the flexible substrate 12, and the input side of each circuit component 15 is connected to the Hall elements 13 and 14. The circuit component 15 compares and amplifies two detection signals from the Hall elements 13 and 14, and calculates an average value of the two detection signals. And the circuit component 15
The output side is connected to the pin terminal 2 and outputs a signal corresponding to the rotation angle θ to the outside.

Reference numeral 16 denotes a lever integrally fixed to the lower end of the rotating shaft 4. The central portion of the lever 16 is caulked and fixed to the rotating shaft 4, and extends outward in the radial direction. The tip is engaged with a lever (not shown) on the throttle valve side. The lever 16 rotates the rotating shaft 4 in response to opening and closing operations of the throttle valve.

Reference numeral 17 denotes a return spring disposed in the spring chamber B of the casing 1. The return spring 17 is formed by a coil spring or the like, one end of which is hooked to the bottom of the partition wall 1B, and the other end thereof. It is hooked on a lever 16. The return spring 17 always urges the lever 16 together with the rotating shaft 4 and the rotating plate 6 to the initial position O2 shown in FIG.

Reference numeral 18 denotes a cover for covering the cylindrical portion 1A of the casing 1. The cover 18 closes the accommodation room A of the casing 1 and protects the accommodation room A from external dust and the like. Also,
The cover 18 is in contact with the upper surface of the yoke support tube 3, and fixes the yoke support tube 3 between the yoke support tube 3 and the partition wall 1 </ b> B of the casing 1.

The turning angle detecting device according to the present embodiment comprises a two-pole type turning angle detecting device composed of the two yokes 8 and 9 as described above.
This will be described with reference to FIG.

First, when the magnet 7 is at the initial position O2, the convex arcuate surface 7A of the magnet 7 is located at the center between the first magnetic pole piece 8A and the second magnetic pole piece 9A which are circumferentially separated. I have. At this time, since the convex circular arc surface portions 7A and 7B of the magnet 7 do not face any of the pole piece portions 8A and 9A, the magnetic flux from the magnet 7 hardly passes through the yokes 8 and 9.

Next, when the throttle valve is opened, the convex arc portions 7A and 7B of the magnet 7 are moved to the initial position O.
2 to the right in the circumferential direction with a rotation angle + θ. At this time, the convex arc surface 7A of the magnet 7 faces the concave arc surface 8A1 of the first pole piece 8A, and the convex arc surface 7B faces the concave arc surface 9A1 of the second pole piece 9A. Thereby, the magnetic flux of the magnet 7 is transmitted to the first yoke 8 and the second yoke 8.
And the first and second Hall elements 13, 1 through the yoke 9
It is led to 4. At this time, each of the Hall elements 13 and 14 outputs a positive detection signal corresponding to the magnetic flux density passing through the yokes 8 and 9.

On the other hand, when the throttle valve is closed, the convex arcuate surface portions 7A and 7B of the magnet 7 are in the initial position O.
2 and turns to the left in the circumferential direction at a turning angle of -θ. At this time, the convex arc surface 7A of the magnet 7 faces the concave arc surface 9A1 of the second pole piece 9A, and the convex arc surface 7B faces the concave arc surface 8A1 of the first pole piece 8A. Thereby, the magnetic flux of the magnet 7 is transmitted to the first yoke 8 and the second yoke 8.
And the first and second Hall elements 13, 1 through the yoke 9
It is led to 4. At this time, each of the Hall elements 13 and 14 outputs a negative detection signal corresponding to the magnetic flux density passing through the yokes 8 and 9.

As described above, a detection signal is output from each of the Hall elements 13 and 14 substantially in proportion to the rotation angle θ.
Using this detection signal, the rotation angle θ of the rotation shaft 4, that is, the opening degree of the throttle valve can be detected.

Thus, according to the rotation angle detecting device of the present embodiment, the heights H1 and H2 of the first and second magnetic pole pieces 8A and 9A are set to two to two times the height T of the magnet 7. 1
Since the magnification is set to 0 times, the magnet 7 is arranged at the center in the height direction of the first and second magnetic pole piece portions 8A and 9A, and the convex arc-shaped surface portions 7A and 7B are formed on the first and second magnetic pole piece portions 8A. , 9A can be surely opposed to the concave arc surface portions 8A1, 9A1. Thereby, the magnetic flux from the magnet 7 can be prevented from leaking to the outside from the lower side in the axial direction or the like, and the magnetic flux from the magnet 7 can be guided to the Hall elements 13 and 14 through the yokes 8 and 9. For this reason, the Hall elements 13 and 14
Is hardly affected by an external magnetic field or the like and the SN ratio is improved, so that the detection sensitivity of the rotation angle θ can be increased.

Since the two-pole type rotation angle detecting device is constituted by the two yokes 8 and 9, the whole rotation angle detecting device is reduced in size as compared with the case where three or more yokes are used. In addition to this, the structure can be simplified and the manufacturing cost can be reduced.

Further, since the magnetic flux blocking portions 11, 11 are provided between the first and second magnetic pole piece portions 8A, 9A,
The magnetic flux generated by the magnet 7 is suppressed from flowing around the outer periphery of the magnet 7 as shown in the direction of arrow C in FIG. can do. This allows
The magnetic flux that has entered the yokes 8, 9 from the portion where the magnet 7 and the pole piece portions 8A, 9A face each other is applied to the pole piece portions 8A, 9A.
A is prevented from leaking from the circumferential end of the Hall element A, and more magnetic flux is passed through the overhang portions 8B and 9B.
3, 14 and the detection sensitivity of the rotation angle θ can be increased.

The first yoke 8 is composed of an arc-shaped first magnetic pole piece 8A and a plate-like overhang 8B extending radially inward from the magnetic pole piece 8A. Similarly to the first yoke 8, the yoke 9 also includes an arc-shaped magnetic pole piece 9A and a flat overhang 9B. Therefore, the shapes of the yokes 8, 9 can be simplified, and the leakage of the magnetic flux passing through the yokes 8, 9 to the outside can be reduced. Thereby, the Hall elements 13 and 14
Can output a larger detection signal, and can increase the detection sensitivity of the rotation angle θ.

Further, between the magnet 7 and the first and second overhang portions 8B and 9B, 1.5 to 10 mm is provided as a sufficient interval for blocking magnetic flux from the magnet 7 to the Hall elements 13 and 14. Is provided in the axial gap Gs. Therefore, it is possible to prevent the magnetic flux from the magnet 7 from reaching the first and second overhang portions 8B and 9B without passing through the yokes 8 and 9 as shown in the direction of arrow D in FIG. Such a short-circuit magnetic flux can be prevented from being detected by the Hall elements 13 and 14 disposed between the first and second overhang portions 8B and 9B.

When the short-circuit magnetic flux is generated, the Hall elements 13 and 14 detect the short-circuit magnetic flux in addition to the magnetic flux passing through the first and second yokes 8 and 9. , The detection signal increases in the direction of arrow F as shown by the characteristic line b in FIG.
There is a problem that the characteristics tend to be non-linear with respect to the rotation angle θ, and it is difficult to detect the rotation angle θ with high accuracy.

However, in the present embodiment, the axial gap G
Since the occurrence of the shortcut magnetic flux is prevented by s, the Hall elements 13 and 14 can detect the magnetic flux density passing through the yokes 8 and 9 without being affected by the shortcut magnetic flux. As a result, the detection signals output from the Hall elements 13 and 14 can be made closer to a linear characteristic with respect to the rotation angle θ as shown by the characteristic line a in FIG. 8, and the detection accuracy of the rotation angle θ can be improved. Can be improved.

Further, a radial gap G of 2 to 5 mm is provided between the magnet 7 and the first and second pole piece portions 8A and 9A.
r is provided. As a result, the magnetic flux from the magnet 7 is transferred from the circumferential ends of the first and second pole piece portions 8A and 9A into the yokes 8 and 9 by the radial gap Gr as shown in the direction of arrow E in FIG. And the magnetic flux in the magnetic circuit can be rectified. As a result, the detection signals from the Hall elements 13 and 14 can be made closer to linear characteristics with respect to the rotation angle θ, and the detection accuracy of the rotation angle θ can be improved.

The first and second pole piece portions 8A, 9A
Are formed as concave arc portions 8A1 and 9A1 having substantially the same angles as the convex arc portions 7A and 7B of the magnet 7, so that the concave arc portions 8A1 of the first pole piece 8A and the convex arc portions 7A of the magnet 7 are formed. The facing area of the concave arc surface 9A1 of the second pole piece 9A and the convex arc surface 7 of the magnet 7
It can be made substantially equal to the area facing B. Thereby, the first and second pole piece portions 8 with respect to the magnet 7 are formed.
The changes in the opposing areas of A and 9A can be made substantially coincident with each other, and the two opposing areas can be changed corresponding to the rotation angle θ. For this reason, the magnetic flux density in the yokes 8 and 9 can be changed more greatly according to the rotation angle θ, and the detection sensitivity of the rotation angle θ can be improved.

The convex arc surface portions 7A, 7 of the magnet 7
Since the angle .alpha.1 of B and the angle .alpha.2 of the first and second pole pieces 8A and 9A are set at 70.degree. To 110.degree., Preferably 90.degree., The magnet 7 is connected to the first and second pole pieces 8A. , 9
When the magnet 7 is disposed at the initial position O2 between A, the facing area between the magnet 7 and the first and second pole pieces 8A and 9A can be minimized. When the magnet 7 is rotated from the initial position O2 rightward and leftward in the circumferential direction, the rotation angle θ at this time is obtained.
And the first and second pole piece portions 8A, 9
The area facing A can be increased. For this reason,
The magnetic flux density in the yokes 8 and 9 can be increased in accordance with the rotation angle θ, and the Hall elements 13 and 14 allow the rotation angle θ
Can be output.

In the above-described embodiment, two Hall elements 13 and 14 are provided between the first and second overhang portions. However, one Hall element 13 and 14 are provided between the first and second overhang portions.
A configuration may be employed in which a plurality of Hall elements are provided, and the magnetic flux passing between the first and second overhang portions is detected by the one Hall element.

[0064]

As described above in detail, according to the first aspect of the present invention, the height of the first and second yokes is set to be 2 to 10 times the height of the magnet. The first and second yokes are arranged at the center in the height direction,
The second yoke can be reliably faced. Accordingly, it is possible to prevent the magnetic flux from the magnet from leaking from the lower side in the axial direction to the outside, and to guide more magnetic flux from the magnet to the signal output unit. For this reason, the signal output from the signal output means can be increased, and the detection sensitivity of the rotation angle can be increased.

Further, according to the first aspect of the present invention, the two-pole type rotation angle detecting device is constituted by two yokes.
Compared with the case where more than two yokes are used, the whole rotation angle detecting device can be reduced in size, the structure can be simplified, and the manufacturing cost can be reduced.

Further, according to the second aspect of the present invention, since the magnetic flux blocking portion is provided between the first and second yokes, the magnetic material is surrounded almost all around the magnet by a magnetic material. Further, it is possible to suppress the generation of the leakage magnetic flux in which the magnetic flux by the magnet goes around the outer periphery of the magnet. Thereby, the magnetic flux of the yoke can be prevented from leaking to the outside, more magnetic flux can be guided to the signal output means, and the detection sensitivity of the rotation angle can be increased.

According to the third aspect of the present invention, since an axial gap is provided between the first and second overhang portions and the magnet, the magnet reaches the overhang portion without passing through the yoke from the magnet. The occurrence of a short-circuit magnetic flux can be prevented. Accordingly, the Hall element can detect the magnetic flux density passing through the yoke and output a signal proportional to the rotation angle, thereby improving the detection accuracy of the rotation angle.

According to the fourth aspect of the present invention, a radial gap is provided between the first and second magnetic pole pieces and the magnet, so that the magnetic flux from the magnet is supplied to the first and second magnetic poles. It is possible to reduce the entry into the yoke from the circumferential end or the like of the one part. Accordingly, the signal output unit can output a detection signal having a more linear characteristic with respect to the rotation angle, and can improve the detection accuracy of the rotation angle.

According to the fifth aspect of the present invention, the first and second magnetic pole piece portions are formed with concave arc surface portions coaxially opposed to the convex arc surface portions of the magnet. The area facing the magnet can be made substantially equal to the area facing the second pole piece and the magnet. Therefore, the two opposing areas can be changed in accordance with the rotation angle, and the magnetic flux density in the yoke can be changed more greatly in accordance with the rotation angle, and the detection sensitivity of the rotation angle can be increased. .

[Brief description of the drawings]

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

FIG. 2 is a plan view showing a part of a cover of the rotation angle detection device according to the embodiment, which is cut away.

FIG. 3 is a cross-sectional view showing a first yoke, a second yoke, a magnet, and the like according to the embodiment, as viewed from a direction indicated by arrows III-III in FIG.

FIG. 4 shows a magnet, a first yoke,
It is a perspective view showing a 2nd yoke etc.

FIG. 5 shows a magnet, a first yoke,
It is a top view which shows a 2nd yoke etc.

FIG. 6 shows a magnet, a first yoke,
It is a longitudinal section showing a 2nd yoke and a hall element.

FIG. 7 is a schematic configuration diagram showing an arrangement relationship among a magnet, a first yoke, a second yoke, and a Hall element used in the rotation angle detection device.

FIG. 8 is a characteristic diagram showing a relationship between a rotation angle and a detection signal output from a Hall element.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Casing 7 Magnet 7A, 7B Convex arc surface part 8 1st yoke 8A 1st pole piece 8A1 1st concave arc surface 8B 1st overhang part 9 2nd yoke 9A 2nd pole piece 9A1 2nd 9B Second overhang portion 11 Magnetic flux cut-off portion 13, 14 Hall element (signal output means) Gs axial gap Gr radial gap

Claims (5)

[Claims] 1. A magnet rotatably provided, and first and second overhangs extending radially inward from first and second magnetic pole pieces radially opposed to each other with the magnet interposed therebetween. A first and a second yoke, which are formed by overlapping each other on the center of rotation of the magnet, and a first and a second overhanging portion that constitute the first and the second yokes, Signal output means for outputting a signal corresponding to the facing area of the magnet and the first and second yokes, wherein the height of the first and second yokes in the axial direction is set to A rotation angle detection device configured to be set to 2 to 10 times. 2. A structure in which a magnetic flux blocking portion for blocking a magnetic flux directed in a circumferential direction between the first and second magnetic pole pieces is provided between the first and second magnetic pole pieces. 3. The rotation angle detection device according to 1. 3. An axial gap of 1.5 to 10 mm is provided between the first and second overhang portions and the magnet to block a magnetic flux from the magnet to the signal output means. 3. The rotation angle detection device according to 1 or 2. 4. The rotation angle detecting device according to claim 1, wherein a radial gap of 2 to 5 mm is provided between the first and second magnetic pole pieces and the magnet. 5. The magnet according to claim 5, wherein both end surfaces having different magnetic poles with respect to a center of rotation of the magnet are formed as convex arcuate surface portions, and the first and second magnetic pole pieces are formed by turning the magnet. 3. A method according to claim 1, wherein said concave arc surface portion coaxially opposing each convex arc surface portion with respect to the moving center.
The rotation angle detection device according to 3 or 4.