JP2001165609A - Angle sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate the influence of the magnetic field of one magnet provided within an angle sensor on a wheel element for detecting the displacement magnetic field of the other magnet to precisely detect a rotating angle. SOLUTION: When a second magnetic detecting element H2 is shielded by a magnetic shield member 70, the influence of the magnetic field of the first magnet and other external magnetic fields to pass the magnetic detecting surface H2a of the second magnetic detecting element H2 can be eliminated. Since the second magnetic detecting element H2 thus can detect only the magnetic field of a second magnet M2, the noise caused by the magnetic field of the first magnet M1 and other external magnetic fields can be prevented, and the rotating angle can be precisely detected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an angle sensor for detecting a steering angle (rotation angle) of a steering wheel of an automobile, and more particularly, to an angle sensor having improved detection accuracy of the rotation angle.

[0002]

2. Description of the Related Art FIG.
FIG. 3 is a plan view showing the internal structure of a conventional angle sensor proposed in No. 3115, for example, for detecting a steering angle of a steering wheel (detected shaft) of an automobile with high accuracy.
FIG. 5 is a diagram showing output characteristics of the angle sensor with respect to the rotation angle.

The angle sensor 1 shown in FIG. 4 has a rotating body 3 provided in a case 2 made of a synthetic resin material such as plastic. The rotating body 3 is formed of a synthetic resin material or the like in a cylindrical shape, and is rotatably supported by the case 2. The steering wheel of the automobile is inserted into the rotating body 3, and the rotating body 3 is rotated together with the steering wheel in clockwise and counterclockwise directions. A plurality of helical gears 3a are provided on the outer peripheral surface of the rotating body 3.
Are formed over the entire circumference.

In the case 2, a rotating shaft 9 having an X-axis as an axis is rotatably provided. A drive gear 8 and a first magnet 5A are coaxially provided on the rotating shaft 9. A plurality of helical gears 8 a are formed on the outer peripheral surface of the drive gear 8 over the entire circumference, and mesh with the helical gear 3 a of the rotating body 3. The rotating shaft 9 is made of a metal material such as brass or aluminum, and has a helical screw shaft 9a formed from the center to one end, and the detector 4 is provided on the screw shaft 9a.

[0005] The detection body 4 has a through hole 4a formed from one end surface to the other end surface in the movement direction (X direction). A female screw (not shown) that meshes with the screw shaft 9a formed on the rotating shaft 9 is formed on the inner peripheral surface of the through hole 4a. A second magnet 5B is attached to the lower surface of the detector 4 by insert formation or the like. The detection body 4 is guided in the case 2 so as to move linearly in the X direction, and the rotating body 3 rotates, and the driving gear 8
The rotation of the rotation shaft 9 causes the detection body 4 and the second
Is reciprocated in the X direction.

On the fixing member 7 of the case 2, first and second wheel elements (magnetic detection elements) 6A and 6B are provided on the sides facing the first and second magnets 5A and 5B, respectively. ing. The first Hall element 6A
Is composed of a pair of magnetic sensing elements. And
When the rotating shaft 9 is rotated, the first wheel element 6A
Outputs a sine wave having a different phase as shown in FIG. 5 by detecting the magnetic displacement of the first magnet 5A,
By combining them, the fine rotation angle of the steering wheel is detected. Further, when the second magnet 5B reciprocates in the X direction, its magnetic displacement is changed to the second wheel element 6B.
By detecting B, the value 103 that changes linearly linearly over the entire rotation angle range of the steering wheel as shown in FIG. 5 is output, and the coarse rotation angle of the steering wheel is detected.

Then, the first and second wheel elements 6
The rotation angle of the steering wheel is detected with high accuracy by the detection signals detected from A and 6B.

[0008]

However, in the conventional angle sensor 1, since the first magnet 5A is made of a ferromagnetic material having a high magnetic field strength, the magnetic field generated by the first magnet 5A is the second magnet. In some cases, the second wheel element 6B picks up not only the displacement magnetic field of the second magnet 5B but also the displacement magnetic field of the first magnet 5A.

That is, the second wheel element 6B detects a magnetic field in the vertical direction (Z direction) of the second magnet 5B and uses this as an output signal. On the other hand, the magnetic field of the first magnet 5A is composed of an N-pole magnetized on a part of the outer peripheral surface of the ring-shaped first magnet 5A and an S-pole magnetized at a position axially symmetric to the N-pole. Occur between. And the first magnet 5
When A is rotated about the rotation axis 9, the first magnet 5
The magnetic field of A may pass through the magnetic detection surface of the second wheel element 6B. For this reason, there is a problem that a signal caused by the first magnet 5A is superimposed as noise on an output signal of the second wheel element 6B, and detection accuracy of the rotation angle of the detected shaft (steering wheel) is reduced.

Conventionally, the above problem has been solved by securing a sufficient distance between the second wheel element 6B and the first magnet 5A so that the second wheel element 6B is not affected by the first magnet 5A. The method has a problem that the angle sensor becomes large.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and the rotation angle of a rotating body is reduced by preventing the magnetic field of a first magnet from affecting a second magnetic detection element (wheel element). It is an object of the present invention to provide an angle sensor capable of detecting with high accuracy.

[0012]

According to the present invention, there is provided a rotating body attached to a first rotating shaft and rotating integrally with the first rotating shaft; A second rotating shaft rotated in a corresponding direction, a first magnet provided coaxially with the second rotating shaft and rotating integrally with the second rotating shaft, and facing the first magnet A first magnetic detection element provided at a position and detecting a fine rotation angle of the first rotator; and a converter for converting the rotational force of the second rotary shaft into a linear movement of a second magnet. An angle sensor fixed to a position facing the second magnet and including a second magnetic detection element that detects a displacement magnetic field of the second magnet and detects a coarse rotation angle of the first rotation shaft. A magnetic shield member is provided around the second magnetic detection element. Field member is characterized in that the magnetically shielding said from the magnetic field other than the field where the second magnet is generated the second magnetic detecting element.

In the above, the magnetic shield member comprises:
Preferably, of the magnetic field generated by the first magnet, one that magnetically shields a magnetic field component that is going to pass through the magnetic detection surface of the second magnetic detection element.

In the present invention, the magnetic field detected by the second magnetic detecting element can be only the magnetic field of the second magnet.
That is, since the magnetic field of the first magnet and other external magnetic fields that pass through the magnetic detection surface of the second magnetic detection element can be shielded, the second magnetic detection element is affected by these magnetic fields. It becomes difficult. Therefore, since only the displacement magnetic field of the second magnet can be reliably detected, the coarse rotation angle of the detected shaft (steering wheel) can be detected with high accuracy.

Specifically, the magnetic shield member is provided in a plate shape at least above and below a magnetic detection surface of the second magnetic detection element.

Thus, it is possible to reliably shield the magnetic field of the first magnet and other external magnetic fields passing through the magnetic detection surface of the second magnetic detection element.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is a front sectional view showing the internal structure of an angle sensor, and detects a steering angle of a steering wheel of an automobile, for example, with high accuracy. FIG. 2 is an exploded perspective view showing a main part of the angle sensor, and FIG. 3 is a sectional view taken along line AA of FIG.

In the angle sensor 10 shown in FIG.
Denotes a lower case, and reference numeral 13 denotes a rotating body. The rotating body 13 is formed in a cylindrical shape from a synthetic resin material, and is disposed in the lower case 12 in a clockwise direction (α1
Direction) and counterclockwise (α2 direction). The center of the rotating body 13 is a hollow,
The steering wheel Sh (first rotation axis: detected axis) of the automobile is inserted therein (see FIG. 2). Rotating body 1
Protrusions 13a, 13b extending in the axial direction are formed on the inner peripheral surface of the steering wheel 3 so as to protrude therefrom, and can be fitted into concave portions (not shown) formed on the outer peripheral surface of the steering wheel Sh.
When the steering wheel Sh rotates, the rotating body 13 is rotated accordingly. As shown in FIG. 2, a helical gear 13 </ b> A is formed around the outer peripheral surface of the rotating body 13. I have.

On the other hand, below the lower case 12 (Z2 in FIG. 1)
(Direction), a unit case 17 is provided. The unit case 17 is formed from a synthetic resin obtained by injection molding or the like, and as shown in FIGS.
L-shaped locking pieces 17A and 17B are formed at both ends in two directions. The locking projections 17A1, 17 protruding in the X1 and X2 directions are provided outside the locking pieces 17A, 17B.
B1 are respectively formed.

On the X1 and X2 sides of the lower case 12, locking recesses 12A and 12B are formed, respectively. The engaging protrusions 17A1 and 17B1 of the unit case 17 are fitted into the engaging recesses 12A and 12B of the lower case 12 (concavo-convex fitting), whereby the unit case 17 is formed.
Can be locked and fixed to the lower case 12.

As shown in FIGS. 1 and 3, circular positioning recesses 17C and 17D are formed on the surface of the unit case 17 on the Y1 side in the drawing. Further, positioning projections 12C (not shown) and 12D protrude from the surface of the lower case 12 facing the positioning recesses 17C and 17D (see FIG. 3).
Therefore, the locking projections 17A1 and 17B1 can be
2A and 12B, the lower case 12
By fitting the positioning concave portions 17C and 17D of the unit case 17 into the positioning convex portions 12C and 12D, it is possible to accurately position and fix the unit case 17 at a lower position in the lower case 12.

X1 and X2 of the unit case 17
The support pieces 17a extending in the illustrated Z1 direction
17b, and a circular support portion 17a1 and a support portion 17b1 are formed at the tip thereof. The support part 17a
In the upper part of the first and the first parts 17b1, there are formed defective parts 17a2 and 17b2 each having an open end in the Z1 direction, and both ends of a rotating shaft 30 to be described later are supported through the defective parts 17a2 and 17b2. 17b1.

Between the support pieces 17a and 17b, a first
17d and a second pedestal portion 17e. As shown in FIG. 2, the first pedestal portion 17d is formed in a substantially V shape, and a pair of first magnetic members is provided on the back of the V-shaped inclined surface (inside the first pedestal portion 17d). Detection element H1
(See FIG. 1) is provided with the outer shape positioned. On the other hand, the second pedestal portion 17e has a rectangular parallelepiped shape extending in the X direction in the drawing, and rails (guide members) 17e1 and 17e2 having a convex cross section are provided on both sides of the upper surface thereof in the X direction. As shown in FIGS. 1 and 3, the second magnetic sensing element H2 is provided in the center of the inside of the second pedestal portion 17e.
Are provided with the outer shape positioned. And
The detection body 20 faces the upper part of the second base 17e. The first magnetic detection element H1 and the second magnetic detection element H2 are, for example, wheel elements, MR elements
An element, a magnetic flux detection coil, or the like can be used.

The detection body 20 mainly comprises a holder 21, an elastic support member 22, and a fitting member 23.
The holder 21 is made of a synthetic resin, and has a planar rectangular space area 21A formed therein. Four sliding pieces 21a, 21a, 21a, 2 protruding in the illustrated Y-axis direction are provided at four corners of the holder 21 surrounding the space area 21A.
1a are formed. The bottom surface of each sliding piece 21a is formed as a smooth surface having a small coefficient of friction.
The width interval of the bottom surface (a) (the interval in the Y direction) is the same as the width interval between the rails 17e1 and 17e2. Therefore, the holder 21 is capable of linearly reciprocating in the X direction in the drawing, with each sliding piece 21a being guided by the rails 17e1 and 17e2.

In the space area 21A of the holder 21,
A second magnet M2 made of a magnetic material such as ferrite magnetized to a pair of N and S poles along the axial direction is held. Then, the magnetically attached surface of the second magnet M2 and the second magnetic detection element H2 are in a relationship of facing each other. A fixed portion 21f is provided on the illustrated Y side of the holder 21.
The fixing portion 21f has a convex portion 21 protruding in the Z1 direction in the drawing.
g, 21h are formed.

The elastic support member 22 is formed by pressing and / or punching a thin metal plate. A base end 22 of the elastic support member 22 on the Y1 side in the drawing.
In A, holes 22a, 2 provided with a cross-shaped notch are provided.
2b are formed, and the convex portions 21g and 21h of the holder 21 are inserted into the holes 22a and 22b, so that the base end 22A which is one end of the elastic support member 22 is formed.
However, it is fixed to the fixing portion 21f of the holder 21A in a cantilever state. The other end (fixed end side) on the Y2 side in the drawing of the elastic support member 22 is a support portion 22B. When the base end portion 22A is fixed to the fixing portion 21f to be in a cantilevered support state, the support portion 22B becomes a free end and is elastically supported in the Z direction in the figure. Holes 22c, 2 are provided in the support portion 22B.
2d is provided, and between the hole 22c and the hole 22d, support arms 22f and 22f extending in the Y1 and Y2 directions are shown.
22f, 22f, 22f are integrally formed.

As shown in FIG. 2, a fitting member 23 is fixed on the support portion 22B of the elastic support member 22. The fitting member 23 is formed of a resin material. Through holes are formed at both ends of the base 23A in the X1 and X2 directions from one end surface to the other end surface of the cylinder, and the cylinder is formed by a surface parallel to the XY plane. A pair of cut semi-hollow cylindrical fitting portions 23
a and 23b are formed. The fitting portions 23a, 23
Female threads are formed on the inner surfaces 23c, 23c of the U-shaped cross section b. The base 23 of the fitting member 23
Projections 23d and 23e similar to the projections 21g and 21h formed on the holder 21 are formed on the bottom surface of A (the surface on the Z2 side) so as to protrude in the Z2 direction (not shown). The projections 23d and 23e are inserted into the holes 22c and 22d formed in the support portion 22B of the elastic support member 22, so that the fitting member 23 is supported on the free end side support portion 22B of the elastic support member 22. Is held. And the fitting member 2
By deforming and holding the distal end of each support arm 22f so as to wind each support arm 22f around the base 23A of No. 3,
The fitting member 23 is firmly held by the support portion 22B.
As described above, when the fitting member 23 is fixed to the support portion 22B of the elastic support member 22, the fitting member 23 is installed directly above the space area 21A of the holder 21, and is shown by the elastic force of the elastic support member 22. It is elastically supported in the Z direction and is pressed against a screw shaft 30a described later.

A drive gear 36 is fixed to the rotary shaft 30, and the drive gear 36 is firmly fitted to the rotary shaft 30 and rotates together.
On the outer peripheral surface of the drive gear 36, a helical gear 36A of the same module as the helical gear 13A formed on the outer peripheral surface of the rotating body 13 is provided. A spiral screw shaft 30 a is formed on the rotating shaft 30 from a position adjacent to the drive gear 36 to the left end of the rotating shaft 30. The pitch of the screw groove of the screw shaft 30a is determined by the inner surfaces 23c and 23 of the fitting portions 23a and 23b.
It is formed at the same pitch as the female screw formed in c.

When both ends of the rotary shaft 30 are supported between the support portion 17a1 of the support piece 17a and the support piece 17b1 of the support piece 17b, the screw shaft 30a is
The fitting members 23 provided at the two free ends are set so as to be located on an elastic movement trajectory. Therefore, the screw shaft 30a and the fitting portions 23a and 23b of the fitting member 23 provided at the free end of the elastic support member 22 mesh with each other. Thus, a conversion unit that converts the rotation of the rotation shaft 30 into a linear motion of the detection body 20 is configured.

The right end of the drive gear 36 in the figure is a thick shaft extension 36 extending from the shaft center of the drive gear 36 in the X1 direction.
a and a thin shaft extension 36b are formed. The thin shaft extension 36b is connected to the thick shaft extension 36a in the drawing X
It is formed in one direction. The thick shaft extension 36a includes:
The auxiliary gear 40 is rotatably extrapolated. A biasing member 50A is provided between the right end surface of the drive gear 36 and the auxiliary gear 40.
Is provided. The urging member 50A in the embodiment shown in FIGS. 1 and 2 is, for example, a torsion spring 50, and can urge the auxiliary gear 40 in the β1 direction. One end 50a of the urging member 50A is connected to the
1, and is inserted into an insertion hole 36c formed inside the drive gear 36 as shown in FIG. The other end 50b of the urging member 50A is hooked on a hook 40a formed in the opposing surface of the auxiliary gear 40.

The outer peripheral surface of the auxiliary gear 40 is formed in a helical gear shape. Further, the auxiliary gear 40 has a bevel gear shape having a small outer diameter on the side facing the drive gear 36 and a large outer diameter on the opposite side. That is, as shown in FIG. 1, the auxiliary gear 40 has a bevel gear shape in which the teeth are inclined (tapered) along the circumferential direction of the rotating body 13 in the axial cross-sectional shape. Therefore, the auxiliary gear 40 has a helical gear shape and a bevel gear shape (helical gear 40
A).

A ring-shaped washer 55 and a first magnet M1 are provided on the right end side of the auxiliary gear 40 in the figure. The inner diameter of the first magnet M1 is formed to be substantially the same as the outer diameter of the small shaft extension 36b of the drive gear 36, and the first magnet M1 is fitted to the small shaft extension 36b. Thereby, it can be fixed to the rotating shaft 30.

The outer peripheral surface of the first magnet M1 has an N-pole and an S-pole once or twice each time the first magnet M1 makes one rotation. It is magnetized so as to pass through H1.

The both surfaces of the washer 55 are formed as smooth surfaces having a small coefficient of friction. By inserting the washer 55 between the auxiliary gear 40 and the magnet M1, the end surface of the auxiliary gear 40 and the magnet M1 are formed. The sliding friction generated between the end face and the end face can be reduced. Further, by providing the speed nut 56 so as to contact the end face of the magnet M1 and the end face of the drive gear 36, the auxiliary gear 40, the magnet M1
Is prevented from falling out.

The rotating shaft 30 including the driving gear 36, the auxiliary gear 40, the urging member 50A, the washer 55, and the first magnet M1 is connected to the supporting portion 17a1 of the supporting piece 17a and the supporting portion 17b1 of the supporting piece 17b. Supported between. At this time, bearing members 60 are mounted on both ends of the rotating shaft 30, respectively. The bearing member 60 is formed of a synthetic resin material, and includes a cylindrical bearing 61 and a flange 62 provided on one surface of the bearing 61. Then, both ends of the rotating shaft 30 are
The outer peripheral surfaces of the bearing portions 61, 61 are supported by the support portion 17a1 and the support piece 17b1, respectively, in a state where the outer peripheral surfaces of the bearing portions 61, 61 are inserted through the defective portions 17a2 and 17b2 through the 0, 60. This prevents the rotational shaft 30 from being displaced in the radial direction (the direction perpendicular to the rotational shaft 9).

As shown in FIG. 1, when the rotary shaft 30 is mounted inside the unit case 17, the first magnet M1 faces the inclined surface of the first pedestal portion 17d formed in a substantially V shape. It is installed in the position where it does. Also, the first pedestal portion 17
The drive gear 36 is disposed between the second seat 17d and the second pedestal 17e.

Further, the fitting portions 23a, 23 of the fitting member 23
3b is engaged with the screw shaft 30a.
At this time, the urging force of the elastic support member 22 causes the fitting portion 2
3a and 23b press the screw shaft 30a in the Z1 direction, so that the screw shaft 30a and the fitting portions 23a and 23
b can reduce backlash between the inner surfaces 23c and 23c.

Since the elastic support member 22 is integrally formed of a single metal plate, the entire fitting member 23 can be urged horizontally in the Z1 direction. Thus, no biasing force is generated on both ends of the fitting portion 23a and the fitting portion 23b with respect to the screw shaft 30a. Therefore, since the fitting portion 23a and the fitting portion 23b can repress the screw shaft 30a with a uniform urging force, the screw shaft 3
0a and the inner surfaces 23c, 23c of the fitting portions 23a, 23b can be evenly brought into close contact with each other, and the play between them can be suppressed.

When the unit case 17 to which the above-described rotary shaft 30 is mounted is fixed to a lower position in the lower case 12, and the rotating body 13 is further provided in the lower case 12,
The helical gear 13A of the rotating body 13 and the helical gear 36A of the drive gear 36 mesh with each other in a screw gear relationship. Then, as shown in FIG. 3, when the upper case 11 is mounted from above the lower case 12, the unit case 17 and the rotating body 30 can be sealed between the upper case 11 and the lower case 12. At this time, as shown in FIGS. 1 to 3, between the lower case 12 and the upper case 11, a magnetic shield member (magnetic shield member) 70 having a U-shaped cross section that covers the second magnetic detection element H2 is provided. Is provided.
The magnetic shield member 70 is formed by bending a thin plate-shaped magnetic material, and includes an upper surface 71, a lower surface 72, and an abutting surface 7.
3 has a three-sided structure. As the magnetic material, for example, iron (Fe) is generally used. In addition, for example, the iron (Fe) is mainly used, and for example, cobalt (Co),
Nickel (Ni), silicon (Si), carbon (C) and the like may be contained in appropriate amounts. The lower surface 72 is locked between locking portions 12 a provided in the lower case 12, and the upper surface 71 is locked on the locking protrusion 12 of the lower case 12.
b. Thus, the magnetic detection surface H2a of the second magnetic detection element H2 is sandwiched from above and below (Z).

As shown in FIGS. 2 and 3, the magnetic shield member 70 has a leaf spring 74 formed by stamping a part of the contact surface 73. Then, the leaf spring 74 abuts on the upper case 11 and presses the magnetic shield member 70 in the illustrated Y1 direction,
The magnetic shield member 70 includes the upper case 11 and the lower case 1
2 is fixed.

The operation of the angle sensor will be described below.
The angle sensor 10 is mounted on a steering wheel (first axis) Sh of an automobile, and the steering wheel Sh
Is rotated in the illustrated α1 or α2 direction, the driving gear 36 and the auxiliary gear 40 meshing with the rotating body 13
It is rotated in the 1 or β2 direction. At this time, the rotating shaft 30 and the first magnet M1 fixed to the rotating shaft 30 are simultaneously rotated in the β1 or β2 direction.

By this rotation, the N pole and the S pole magnetized on the outer peripheral surface of the first magnet M1 pass through the first magnetic detecting element H1. The pair of first magnetic detecting elements H1 detect the displacement magnetic field of the first magnet M1 and generate sine waves 101 and 102 having different phases similar to the conventional example shown in FIG. The fine rotation angle position of the rotator 13 (steering wheel Sh) is output by alternately using the areas in which the output voltage changes greatly with respect to the rotation angle. The number and waveform of the signals are not limited to the above, and it is sufficient that a waveform having a large output value change with respect to the rotation amount within a specific period can be obtained.

When the rotating shaft 30 is rotated in the β1 or β2 direction, a feeding force in the X1 or X2 direction (thrust direction) is applied to the fitting portions 23a and 23b of the holder 21 by the screw shaft 30a. Given. As a result, each sliding piece 21a of the holder 21 is
e slides on the rails 17e1 and 17e2, and is moved linearly in the X1 or X2 direction in the figure. That is, the screw shaft 30a of the rotating shaft 30 and the fitting portions 23a and 23b of the fitting member 23 are converting portions that convert the rotating motion of the rotating shaft 30 in the β1 or β2 direction into linear motion.
The conversion unit moves the detection body 20 in the X1 or X2 direction. Then, the second magnetic detecting element H2 detects a change in the component of the magnetic field of the second magnet M2 in the Z direction, and at least over the moving range, a value 103 (see FIG. 5) that changes linearly in a linear manner as in the related art. ) Is detected, and the coarse rotation angle position of the rotating body 13 is output.

In the above, the second magnetic sensing element H2
, A magnetic shield member 70 is provided around the upper plate 7.
The first and lower plates 72 are arranged above and below the second magnetic sensing element H2. Thereby, an external magnetic field that is going to pass through the magnetic detection surface H2a of the second magnetic detection element H2 can be shielded. In particular, of the magnetic field of the first magnet M1,
It is possible to effectively magnetically shield a magnetic field component that is going to pass vertically through the magnetic detection surface H2a of the second magnetic detection element H2.

As a result, the detection signal of the second magnetic detection element H2 is hardly affected by an external magnetic field other than the second magnet M2, in particular, by the noise of the first magnet M1. The coarse rotation angle can be detected with high accuracy.

In the above embodiment, the second magnetic sensing element H2 is shown as being magnetically shielded. However, by covering the first magnet M1 with a magnetic shielding member, the second magnetic sensing element H2 is shielded. May not be affected by the magnetic field of the first magnet M1.

However, it is generally difficult to magnetically shield the magnetic field of the rotating first magnet M1 from the viewpoint of a margin in the case. Further, if a magnetic shield member is provided on the second magnetic detection element H2 side, it is possible to magnetically shield an external magnetic field other than the magnetic field of the first magnet M1, so that the rotation angle can be detected with higher accuracy. Can be.

Further, by providing the magnetic shield member 70, the second magnetic transducer H2 does not need to have a sufficient distance so as not to affect the first magnet M1, so that the size of the angle sensor 10 is reduced. Will be able to do it.

In the above description, the magnetic shield member 70 having a three-sided structure having a U-shaped cross section is shown, but the present invention is not limited to this. That is, by sandwiching the magnetic detection surface H2a of the second magnetic transducer H2 from above and below, it is sufficient that an external magnetic field that passes through the magnetic detection surface H2a can be shielded, and therefore at least opposes the magnetic detection surface H2a. It suffices that the magnetic shield plates are provided on the upper and lower surfaces, respectively.

[0050]

According to the present invention described in detail above, the effect of the magnetic field of the first magnet and the like can be reduced by magnetically shielding the second magnetic sensing element. Accordingly, the second magnetic detection element can detect only the displacement magnetic field of the second magnet, and thus can detect the rotation angle of the steering wheel with high accuracy.

[Brief description of the drawings]

FIG. 1 is a front sectional view showing the internal structure of an angle sensor;

FIG. 2 is an exploded perspective view showing a main part of the angle sensor,

FIG. 3 is a sectional view taken along line AA of FIG. 1;

FIG. 4 is a plan view showing the internal structure of a conventional angle sensor;

FIG. 5 is a diagram showing output characteristics of an angle sensor with respect to a rotation angle;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Angle sensor 13 Rotating body 17 Unit case 20 Detecting body 21 Holder 22 Elastic support member 23 Fitting member 23a, 23b Fitting part 30 Rotating shaft 30a Screw shaft 36 Driving gear 40 Auxiliary gear 50A Biasing member H1 First magnetic detection Element H2 Second magnetic detection element H2a Magnetic detection surface M1 First magnet M2 Second magnet 70 Magnetic shield member

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2F063 AA36 BA08 CA16 DA05 DC04 DD03 EA03 GA52 KA01 KA02 2F077 CC02 JJ03 JJ07 JJ23 NN19 NN24 PP11 QQ05 VV02 3D030 DB19

Claims (3)

[Claims] A first rotating shaft attached to the first rotating shaft;
A rotating body that rotates integrally with the rotating shaft, a second rotating shaft that rotates in a direction corresponding to the rotating direction of the rotating body in conjunction with the rotating body, and is provided coaxially with the second rotating shaft. A first magnet that rotates integrally with the second rotation shaft, and a first magnetic detection element that is provided at a position facing the first magnet and detects a coarse rotation angle of the first rotating body. A converter for converting the rotational force of the second rotating shaft into a linear movement of a second magnet; and a converter fixed to a position facing the second magnet,
A second magnetic detecting element for detecting a displacement magnetic field of the magnet and detecting a coarse rotation angle of the first rotating shaft, wherein a magnetic shield is provided around the second magnetic detecting element. A member is provided, and the magnetic shield member is provided in the second
An angle sensor for magnetically shielding the second magnetic detection element from a magnetic field other than the magnetic field generated by the magnet. 2. The magnetic shield member according to claim 1, wherein a magnetic field component of the magnetic field generated by the first magnet that passes through a magnetic detection surface of the second magnetic detection element is magnetically shielded. The angle sensor according to 1. 3. The angle sensor according to claim 1, wherein the magnetic shield member is provided in a plate shape at least above and below a magnetic detection surface of the second magnetic detection element.