JP4960174B2 - Non-contact rotation angle detection sensor - Google Patents

Description

  The present invention relates to a non-contact rotational angle detection sensor using a magnetic sensitive element.

As a rotation angle detection sensor suitable for detecting the angle of depression of an accelerator pedal in a vehicle or detecting the rotation angle of a shaft that rotates in response to an operation of a shift lever, for example. There is a non-contact type rotational angle detection sensor using a magnetic sensitive element.
As a conventional example of such a non-contact type rotation angle detection sensor, there is one disclosed in Patent Document 1, for example.
JP 05-126512 A

In Patent Document 1, as shown in FIG. 10, a rotation angle detection sensor for detecting a rotation angle of a detection object, which is connected to a detection object (not shown) and rotates together with the detection object. Permanent magnets 101a and 101b are provided, and a change in the magnetic field due to the permanent magnets 101a and 101b when the rotating body 100 rotates is detected by the MR element 102, and the rotation angle of the detected object is detected based on the detected change in the magnetic field. Are disclosed.
In this rotational angle detection sensor, the rotating body 100 and the MR element 102 are accommodated in the housing 103, and in order to prevent the external magnetic field from affecting the detection of the change in the magnetic field by the MR element 102, the housing A shield member 104 such as a PC perm alloy is provided in 103.

In recent years, miniaturization of non-contact type rotation sensors has been demanded.
In the case of the rotation angle detection sensor having the configuration disclosed in Patent Document 1, a shield member 104 is formed inside the housing 103 so as to cover the periphery of the rotation sensor itself (permanent magnets 101a and 101b and the MR element 102). .
Therefore, the shield member 104 does not affect the detection of the change of the magnetic field by the MR element 102 so that, for example, the hysteresis, which is the output characteristic of the rotation angle detection sensor, the output fluctuation due to the fluctuation of the external magnetic field, the magnetic flux density, and the linearity do not change significantly. In addition, it is necessary to provide the shield member 104 at a predetermined distance from the rotation sensor itself.
However, even if the rotation sensor itself can be reduced in size, it is necessary to provide the shield member 104 at a predetermined distance from the rotation sensor itself, and the size of the housing 103 having the shield member 104 therein can be sufficiently reduced. Therefore, there is a problem that the sensor cannot be miniaturized.
In addition, since the shield member 104 formed integrally is adopted and the supply of the shield member 104 requires welding or drawing of a plate-like shield member or the like, in mass production of the rotation angle detection sensor, There is a problem that it is difficult to supply, assemble, and assemble the shield member in the manufacturing process.

  The present invention is a rotation angle detection sensor including a shield member that prevents the influence of an external magnetic field from affecting the detection of the rotation angle of a rotating body, so that the shield member does not affect the output characteristics of the rotation angle detection sensor. An object of the present invention is to provide a rotation angle detection sensor that can reduce the size of the sensor.

  The present invention relates to a ring-shaped permanent magnet that can rotate integrally with a detected object and whose magnetic poles change along the circumferential direction, a ring-shaped yoke that surrounds the outer peripheral surface of the ring-shaped permanent magnet with a certain gap, and a ring-shaped A non-contact rotational angle detection sensor comprising a magnetic sensitive element arranged in a gap formed by dividing a yoke into two along a diameter line, the outer circumferential surface of the ring-shaped yoke being spaced apart by a certain gap The surrounding ring-shaped magnetic shield, the upper magnetic shield disposed with a certain gap from the upper surface of the ring-shaped yoke, and the lower magnetic shield disposed with a certain gap from the lower surface of the ring-shaped yoke are separated from each other. The configuration was provided.

According to the present invention, the magnetic sensing element (ring-shaped magnetic shield, upper magnetic shield, and lower magnetic shield) that is a shield member disposed with a certain gap from the ring-shaped yoke rotates the detected object by the magnetically sensitive element. Angle detection can be prevented from being affected by an external magnetic field.
Further, since each magnetic shield is provided while being separated from each other with a predetermined gap, the magnetic resistance becomes larger than when the magnetic shields are integrally formed, and magnetism is difficult to pass. Therefore, depending on the amount of magnetic resistance that has increased and the magnetism has become difficult to pass, the magnetic flux goes around the magnetic shield to reduce the magnetic flux density of the ring-shaped yoke, and the output characteristics of the rotation angle detection sensor are affected by the magnetic shield. The magnetic shield can be arranged closer to the ring-shaped yoke than the conventional integrally formed magnetic shield.
Therefore, the rotation angle detection sensor can be further downsized.
Furthermore, since the ring-shaped magnetic shield, the upper magnetic shield, and the lower magnetic shield are separately arranged while being separated from each other, the magnetic shield is similar to a conventional rotation angle detection sensor in which these magnetic shields are integrated. There is no need for welding or drawing when supplying.
Accordingly, the supply and assembly of the shield member and the assembly of the sensor in the manufacturing process are not difficult, and the rotation angle detection sensor including the magnetic shield can be easily supplied, so that the rotation angle detection sensor suitable for mass production is obtained.

Examples of the present invention will be described below.
FIG. 1 is an overall configuration diagram of a non-contact type rotation angle detection sensor according to an embodiment, (a) is a top view seen from the axial direction, (b) is a cross-sectional view taken along line AA in (a), (C) is a BB arrow line view in (a). FIG. 2 is an exploded perspective view of the non-contact rotation angle detection sensor according to the embodiment. FIG. 3 is an enlarged plan view showing the permanent magnet.

  As shown in FIG. 2, the rotation angle detection sensor attached to the rotating body 10 that is the detection target of the rotation angle includes the permanent magnet 20 and the magnetism collecting yokes 30 a and 30 b (hereinafter, unless the two are particularly distinguished, And a Hall element 40, which are surrounded by magnetic shields 50a to 50d (hereinafter referred to as "magnetic shield 50" unless otherwise distinguished).

A flange-shaped magnet holding portion 11 is formed to extend in the radial direction in a predetermined range at a substantially central portion in the axial direction of the rotating body 10.
The permanent magnet 20 is fixed to the outer peripheral surface of the magnet holding part 11 and has a ring shape when viewed from above. The axial height of the permanent magnet 20 is the same as the axial height of the magnet holding part 11, and the axial height and radial thickness of the permanent magnet 20 are the same over the entire circumference.
As shown in FIG. 3, the permanent magnet 20 is divided into semicircles on the diameter line (180 ° position in the circumferential direction), and one magnet semicircular part 20 a is on the inner circumference side (side in contact with the magnet holding part 11). Is the N pole, the outer peripheral side is the S pole, and the other magnet semicircular portion 20b has the S pole on the inner peripheral side and the N pole on the outer peripheral side, and has a two-pole structure of N and S in the circumferential direction as a whole.

The first magnetism collecting yoke 30 a and the second magnetism collecting yoke 30 b are arranged so as to surround the outer peripheral surface of the permanent magnet 20 attached to the rotating body 10.
The first magnetism collecting yoke 30a and the second magnetism collecting yoke 30b have semicircular shapes that are the same in plan view when viewed from the axial direction. The ring-shaped yoke is divided into two along the diameter line. Formed.

  As shown in FIG. 1A, the first magnetism collecting yoke 30a and the second magnetism collecting yoke 30b are arranged facing each other with a gap X having a predetermined width. The first magnetism collecting yoke 30a and the second magnetism collecting yoke 30b arranged to face each other accommodate the rotating body 10 and the permanent magnet 20 of the rotation angle detection sensor in the space formed inside thereof. The inner peripheral surfaces of the first magnetic collecting yoke 30a and the second magnetic collecting yoke 30b are opposed to the outer peripheral surface of the permanent magnet 20 with a certain gap Ls.

The height in the axial direction of the first magnetism collecting yoke 30a and the second magnetism collecting yoke 30b is larger than the height in the axial direction of the permanent magnet 20, and the upper surfaces of the first magnetism collecting yoke 30a and the second magnetism collecting yoke 30b, It arrange | positions so that the upper surface of the permanent magnet 20 may correspond.
The thickness W1 in the radial direction of the first magnetism collecting yoke 30a and the second magnetism collecting yoke 30b is a magnetic flux in the magnetism collecting yoke 30 in consideration of the magnetic permeability of the material constituting the magnetism collecting yoke and the magnetic flux density of the permanent magnet 20. Is set to a size that does not saturate.

  In the gap X between the first magnetism collecting yoke 30a and the second magnetism collecting yoke 30b, a linear output type hall element 40 that is a magnetically sensitive element is installed. A signal corresponding to the amount of magnetic flux passing through is output.

In the rotation angle sensor 1 configured as described above, the magnetic flux generated from the permanent magnet 20 passes through the first magnetism collecting yoke 30a and the second magnetism collecting yoke 30b. Here, when the permanent magnet 20 rotates together with the rotating body 10, the ratio of the amount of magnetic flux that passes through the gap X in which the Hall element 40 is installed and the amount of magnetic flux that does not pass through the gap X changes. A different detection value corresponding to the rotation angle of the permanent magnet 20 is output.
Therefore, since the rotation angle of the permanent magnet 20 is known based on the detection value of the Hall element 40, the rotation angle of the detection target (rotary body 10) can be specified.

FIG. 4 is an exploded perspective view of the magnetic shield of the rotation angle sensor according to the embodiment.
FIG. 5 is an overall configuration diagram of the magnetic shield, (a) is a top view seen from the axial direction, (b) is a cross-sectional view taken along the line AA in (a), and (c) is a cross-sectional view along B-- in (a). FIG.
The magnetic shield 50 (the upper magnetic shield 50a, the lower magnetic shield 50b, the first side magnetic shield 50c, and the second side magnetic shield 50d) has an amount of magnetic flux that passes through the gap X in which the Hall element 40 is installed. In order to prevent the magnetic field from being affected by the magnetic field, it is made of perm alloy (PC, PB), electromagnetic copper plate (SUY), silicon steel or the like.
The magnetic shields 50a to 50d are arranged with a predetermined gap from each other while surrounding the permanent magnet 20 and the magnetism collecting yoke 30 of the rotation angle detection sensor.

As shown in FIG. 5 (b), the upper magnetic shield 50a is disposed at a position spaced a predetermined distance L1 upward from the upper ends of the first side magnetic shield 50c and the second side magnetic shield 50d, The magnetic shield 50b is disposed at a position separated by a predetermined distance L2 downward from the lower ends of the first side magnetic shield 50c and the second side magnetic shield 50d.
Here, in the rotation angle detection sensor according to the embodiment, the upper surface of the permanent magnet 20 and the upper surface of the magnetism collecting yoke 30 are arranged so as to coincide with each other (see FIG. 1B). The predetermined distance L1 is set to be larger than the predetermined distance L2 so that the separation distance to the upper magnetic shield 50a and the separation distance from the permanent magnet 20 to the lower magnetic shield 50b are substantially the same.
If the upper magnetic shield 50a and the lower magnetic shield 50b are positioned too close to the permanent magnet 20, a magnetic flux wraps around and the upper magnetic shield 50a and the lower magnetic shield 50b are affected. This is to prevent it.

As shown in FIG. 5A, the first side magnetic shield 50c and the second side magnetic shield 50d are arranged facing each other with a gap Y of a predetermined distance L3.
The first side magnetic shield 50c and the second side magnetic shield 50d have semicircular shapes having the same planar shape when viewed from the axial direction, and two ring-shaped magnetic shields are provided along the diameter line. It is divided and formed.
Here, if a ring-shaped magnetic shield in which the first side magnetic shield 50c and the second side magnetic shield 50d are integrally formed, the magnetic resistance of the magnetic shield is reduced and the magnetism easily passes. It increases and inhibits the function of the magnetism collecting yoke 30.
For this reason, the first side magnetic shield 50c and the second side magnetic shield 50c formed by dividing the ring-shaped magnetic shield into two along the diameter line so that the magnetic resistance does not hinder the function of the magnetic flux collecting yoke 30. A magnetic shield 50d is used.

Each of the upper magnetic shield 50a and the lower magnetic shield 50b has a thin disk shape. The rotating body 10 of the rotation angle sensor is inserted through the central portion, and the permanent magnet 20 of the rotation angle sensor and the first magnet Circular openings 51a and 51b that expose portions of the magnetism collecting yoke 30a and the second magnetism collecting yoke 30b are formed.
The openings 51a and 51b are larger than the inner diameter of the ring-shaped magnetism collecting yoke 30 formed by the first magnetism collecting yoke 30a and the second magnetism collecting yoke 30b arranged facing each other, and smaller than the outer diameter. Has a diameter.
Further, the diameter φ of the upper magnetic shield 50a and the lower magnetic shield 50b is such that the outer circumferential surface of the upper magnetic shield 50a and the outer circumferential surface of the lower magnetic shield 50b are respectively opposed to the first side magnetic shield 50c and the second magnetic shield 50c. The diameter is set to be flush with the outer peripheral surface of the side magnetic shield 50d.
As shown in FIG. 1B, the upper magnetic shield 50 a is disposed at a position away from the upper end of the permanent magnet 20 by a predetermined distance T <b> 1, and the lower magnetic shield 50 b is lower than the lower end of the permanent magnet 20. Are arranged at positions separated by a predetermined distance T2.

The first side magnetic shield 50c and the second side magnetic shield 50d have semicircular shapes having the same planar shape when viewed from the axial direction. The permanent magnet 20 and the magnetic collecting yoke 30 of the rotation angle sensor are accommodated in the circular space.
At this time, the first side magnetic shield 50c and the second side magnetic shield 50d are separated from the outer peripheral surfaces of the first magnetic collecting yoke 30a and the second magnetic collecting yoke 30b by a predetermined interval T3. It arrange | positions so that 30a, 30b may be enclosed.
Here, the predetermined interval T <b> 3 is set to a distance at which the magnetic shield 50 does not interfere with the function of the magnetic collecting yoke 30 by collecting the magnetic shield 50 instead of the magnetic collecting yoke 30.

Furthermore, a line segment connecting the gaps X between the first magnetism collecting yoke 30a and the second magnetism collecting yoke 30b, and the gaps Y between the first side magnetic shield 50c and the second side magnetic shield 50d. The first side magnetic shield 50c and the second side magnetic shield 50d are arranged so that the line segment connecting the two intersects at an angle of approximately 90 degrees (orthogonal), and the position of the gap X is set to the gap Y Is offset by approximately 90 degrees around the rotation axis of the rotating body 10 (see FIG. 1A).
Since the gap Y between the first side magnetic shield 50c and the second side magnetic shield 50d is a place where external magnetism leaks inward, the gap Y is the first where the Hall element 40 is disposed. When the magnetic flux leaks from the magnetic flux collecting yoke 30a and the second magnetic flux collecting yoke 30b in the vicinity of the gap X, the leaked magnetism affects the measurement of the magnetic flux amount by the Hall element 40, and the rotation angle is accurately obtained. Can not be.
Therefore, in order to prevent this, the first side magnetic shield 50c and the second side magnetism are arranged so that the line connecting the gap X and the line connecting the gap Y intersect at an angle of approximately 90 degrees. The shield 50d is arranged so that the gap X and the gap Y are positioned farthest from each other.

Further, the height in the axial direction of the first side magnetic shield 50c and the second side magnetic shield 50d is larger than the height in the axial direction of the magnetism collecting yoke 30, and the first side magnetic shield 50c and the second side magnetic shield 50d. The lower surface of the magnetic shield 50d and the lower surface of the magnetism collecting yoke 30 are arranged so as to substantially coincide with each other.
If the thickness W2 of the first side magnetic shield 50c and the second side magnetic shield 50d is less than 1.0 mm, it is not possible to sufficiently prevent the external magnetic field from affecting the measurement of the magnetic flux amount by the Hall element 40. When the thickness is larger than 1.4 mm, the magnetic flux wraps around the first side magnetic shield 50c and the second side magnetic shield 50d, and the maximum magnetic flux density of the magnetic flux collecting yoke 30 near the Hall element 40 is rapidly reduced. End up. Therefore, the thickness W2 is preferably set to 1.0 mm to 1.4 mm, more preferably in the vicinity of 1.2 mm.

  In FIG. 6, each magnetic shield 50 (upper magnetic shield 50a, lower magnetic shield 50b, first side magnetic shield 50c, second side magnetic shield 50d) is arranged while being separated from each other by the support members 60 and 70. It is explanatory drawing explaining a state, (a) is the top view seen from the axial direction, (b) is the sectional view on the AA line in (a). In FIG. 6A, illustration of the support members 60 and 70 hidden under the upper magnetic shield 50a is omitted.

  The support members 60 and 70 arrange the upper magnetic shield 50a, the lower magnetic shield 50b, the first side magnetic shield 50c, and the second side magnetic shield 50d with a predetermined gap therebetween. The support members 60 and 70 are made of a non-permeable material, and are disposed on the diameter line of the upper magnetic shield 50a having a disk shape in a top view and facing each other with the rotating body 10 in between.

The main body 61 of the support member 60 is attached to, for example, a frame (not shown) via a bolt or the like, and is fixed to the frame while holding the support member 60 in a predetermined position.
An upper magnetic shield 50a is fixed on the upper surface of the upper support portion 62 formed to extend from the upper portion of the main body portion 61 in the direction of the rotating body 10.
A state in which the second side magnetic shield 50d and the magnetism collecting yoke 30 (30a, 30b) are placed on the upper surface of the lower support part 63 formed to extend from the lower part of the main body part 61 in the direction of the rotating body 10. The lower magnetic shield 50b is attached to the lower surface.

The main body 71 of the support member 70 connects the upper support 72 and the lower support 73.
An upper magnetic shield 50a is fixed on the upper surface of the upper support portion 72 formed to extend from the upper portion of the main body portion 71 in the direction of the rotating body 10.
A state in which the first side magnetic shield 50c and the magnetism collecting yoke 30 (30a, 30b) are placed on the upper surface of the lower support portion 73 formed to extend from the lower portion of the main body portion 71 toward the rotating body 10. The lower magnetic shield 50b is attached to the lower surface.

The extension lengths of the lower support portions 63 and 73 of the support members 60 and 70 are set longer than the extension lengths of the upper support portions 62 and 72 in order to place the magnetism collecting yoke 30 (30a, 30b). Has been. Further, the thickness in the height direction of the lower support portions 63 and 73 is set to the same thickness as the separation distance L2 between the lower magnetic shield 50b, the first side magnetic shield 50c, and the second side magnetic shield 50d. .
Further, the separation distance from the lower end of the lower support portions 63 and 73 to the upper end of the upper support portions 62 and 72, that is, the thickness in the height direction of the support members 60 and 70 is determined by the upper magnetic shield 50a. 50c and the second side magnetic shield 50d are set to a length that is arranged at a position separated by a predetermined distance L1 from the upper end to the upper side.
By using the support members 60 and 70 having such a configuration, the magnetic shields 50 can be easily arranged while being separated from each other by a predetermined distance, so that the assembly of the rotation angle detection sensor including the magnetic shield is facilitated.

  The extension length of the upper support portions 62 and 72 in the direction of the rotary body 10 is the upper magnetic shield 50a, and the extension length of the lower support portions 63 and 73 in the direction of the rotary body 10 is the extension length of the magnetic collecting yoke 30. It is preferable that (30a, 30b) is set to a minimum length that can be supported. This is to prevent the measurement of the amount of magnetic flux by the Hall element 40 from being affected.

Each of the magnetic shields 50 (the upper magnetic shield 50a, the lower magnetic shield 50b, the first side magnetic shield 50c, and the second side magnetic shield 50d) is formed inward by the support members 60 and 70 having such a configuration. The permanent magnet 20, the magnetic flux collecting yoke 30 (30a, 30b), and the Hall element 40 are accommodated in the space with a predetermined gap therebetween. This prevents the detection of the rotation angle of the rotating body 10 from being affected by the external magnetic field.
Further, since the magnetic shields 50 are arranged with a predetermined gap from each other, the magnetic resistance becomes larger than when the magnetic shields are integrally formed, and magnetism is difficult to pass.
Therefore, even if the magnetic shield is placed closer to the ring-shaped yoke by the amount that the magnetic resistance is larger and the magnetism is harder to pass than in the case of the integrally formed magnetic shield, the magnetic flux wraps around the magnetic shield and rings. The magnetic flux density of the yoke is not reduced, and the output characteristics of the rotation angle detection sensor are not affected by the magnetic shield. Therefore, the rotation angle detection sensor can be further downsized.

Hereinafter, the effect of the embodiment will be described in comparison with a comparative example using a sensor having a configuration of a conventional example that employs an integrally formed magnetic shield.
In the following description, as shown in FIG. 1B, the diameter of the upper magnetic shield 50a and the lower magnetic shield 50b having a disk shape with a thickness of 0.5 mm is 40 mm (φ = 40 mm). The gap between the outer peripheral surface of the yoke 30 and the inner peripheral surfaces of the first side magnetic shield 50c and the second side magnetic shield 50d is 2 mm (T3 = 2 mm), and the magnetism collecting yoke 30 having a thickness of 1.2 mm. And the upper magnetic shield 50a are 4.7 mm (T1 = 4.7 mm), and the gap between the lower surface of the magnetism collecting yoke 30 and the lower magnetic shield 50b is 1.8 mm. A rotation angle detection sensor is used.
The gap between the upper magnetic shield 50a and the first side magnetic shield 50c and the second side magnetic shield 50d is 3.7 mm (L1 = 3.7 mm), and the lower magnetic shield 50b and the first side The gap between the side magnetic shield 50c and the second side magnetic shield 50d is 0.8 mm (L2 = 0.8 mm), and the gap between the first side magnetic shield 50c and the second side magnetic shield 50d The case where Y is 1.0 mm (L3 = 1.0 mm) is taken as an example, and there is no gap between the upper magnetic shield, the first side magnetic shield, the second side magnetic shield, and the lower magnetic shield (gap). : 0 mm) The case of joining was used as a comparative example.

FIG. 7 is a diagram showing the effect of the embodiment in comparison with the comparative example of the conventional example.
Here, the line connecting the N pole and the S pole of the permanent magnet 20 having a two-pole structure as a whole (diameter line perpendicular to the line connecting the opposing surfaces of the ends of the magnet semicircular portions 20a and 20b) is the first. The position of the permanent magnet 20 when passing through the gap X in which the Hall element 40 is disposed between the first magnetism collecting yoke 30a and the second magnetism collecting yoke 30b is set to a rotation angle of 0 °, as shown in FIG. When the rotation angle is −42.5 ° to 42.5 °, the output voltage of the Hall element 40 is −4.5 V (−42.5 °) and 4.5 V (42.5 °). The line is an ideal straight line.
FIG. 7B shows hysteresis due to the rotation direction of linearity (% FS), which is the deviation of the actual output value from the ideal straight line in the comparative example, and FIG. 7C shows the linearity (% FS) in the example. The hysteresis according to the rotation direction is shown.

As shown in FIG. 7B, in the comparative example, the difference between the linearity when the rotation direction is one direction (outward path) and the linearity when the rotation direction is the reverse direction (return path) is 0 at the maximum. whereas the .58% FS, as shown in (c) of FIG. 7, in the embodiment, a maximum 0.11% FS.
Therefore, it can be seen that the hysteresis is improved by about 0.5% FS (90%) in the example than in the comparative example.

FIG. 8 is a diagram showing the effect of the embodiment in comparison with the comparative example according to the conventional example, and shows the output of the Hall element 40 that changes according to the rotation angle of the permanent magnet 20.
As shown in FIG. 8, in the example, the magnetic flux density detected by the Hall element 40 is 92.7 mTFS, whereas in the comparative example, the magnetic flux density detected by the Hall element 40 is 69.5 mTFS. .
Therefore, it can be seen that the embodiment improves the magnetic flux density detected by the Hall element 40 by about 20.0 mTFS (30%) than the comparative example.
Further, since the magnetic flux density B (mT) when the rotation angle is 0 ° is not shifted in the increasing or decreasing direction, the magnetic shield 50 prevents the external magnetic field from affecting the detection by the Hall element 40. You can see that

FIG. 9 is a diagram showing the effect of the embodiment in comparison with the comparative example according to the conventional example, and shows the linearity of the fluctuation of the output of the Hall element 40 that changes according to the rotation of the permanent magnet 20.
As shown in FIG. 9, in the example, the linearity is 0.45% FS, whereas in the comparative example, it is 0.60% FS.
Therefore, it can be seen that the linearity is improved in the example by about 0.15% FS (25%) than in the comparative example.

As described above, in this embodiment, the ring-shaped permanent magnet 20 that can rotate integrally with the rotating body 10 that is the detection target and whose magnetic poles change along the circumferential direction, and the outer peripheral surface of the ring-shaped permanent magnet 20 Ring-shaped magnetism collecting yoke 30 surrounding the magnet with a certain gap, and first magnetism collecting yoke 30a and second magnetism collecting yoke formed by dividing the ring-shaped magnetism collecting yoke 30 into two along the diameter line A non-contact rotation angle detection sensor including a Hall element 40 disposed in a gap X of 30b, and a first side that is substantially ring-shaped as a whole surrounding the outer peripheral surface of the magnetism collecting yoke 30 with a certain gap. The magnetic shield 50c and the second side magnetic shield 50d, the upper magnetic shield 50a arranged with a certain gap from the upper surface of the magnetism collecting yoke 30, and the lower part arranged with a certain gap from the lower surface of the magnetism collecting yoke 30 Magnetic shield 5 And b has a structure which is provided while separated from each other.
As a result, the magnetic shields (upper magnetic shield 50a, lower magnetic shield 50b, first side magnetic shield 50c, and second side magnetic shield 50d) arranged with a certain gap from the ring-shaped magnetic collecting yoke 30 are provided. The external magnetic field can be prevented from affecting the detection of the rotation angle of the rotating body 10 by the Hall element 40.
In addition, each magnetic shield 50 is disposed separately from the ring-shaped magnetic flux collecting yoke 30 while being spaced apart from each other by a predetermined gap, and the magnetic resistance becomes larger than when the magnetic shields are integrally formed, and the magnetism is reduced. It becomes difficult to pass.
Therefore, depending on the amount of magnetic resistance that has increased and the magnetism has become difficult to pass, the magnetic flux goes around the magnetic shield to reduce the magnetic flux density of the ring-shaped yoke, and the output characteristics of the rotation angle detection sensor are affected by the magnetic shield. The magnetic shield can be disposed closer to the ring-shaped yoke than in the case of the conventional integrally formed magnetic shield. Therefore, the rotation angle detection sensor can be further downsized.
Furthermore, since the magnetic shields are arranged separately while being separated from each other, welding and drawing are not required when providing the magnetic shields as in the case where the magnetic shields are integrally formed. Therefore, unlike the conventional rotation angle detection sensor that employs an integrally formed magnetic shield, assembly and assembly in the manufacturing process do not become difficult.

Here, for example, when one of the upper magnetic shield and the lower magnetic shield is a cup-shaped magnetic shield formed integrally with the first side magnetic shield and the second side magnetic shield, the magnetic shield is joined by welding. In addition, it is necessary to form a cup-shaped magnetic shield by drawing a plate-like member or the like.
However, in the embodiment, since the upper magnetic shield, the lower magnetic shield, and the side magnetic shield are provided so as to be separated from each other, welding or drawing is not required. Therefore, the rotation angle detection sensor according to the embodiment can be easily manufactured.

Further, a line segment connecting the gap Y between the first side magnetic shield 50c and the second side magnetic shield 50d arranged facing each other, and the first magnetism collecting yoke 30a and the second magnetism collecting yoke 30b arranged facing each other. The first side magnetic shield 50c and the second side magnetic shield 50d are arranged so that the line connecting the gap X intersects at an angle of approximately 90 degrees.
Since the gap Y between the first side magnetic shield 50c and the second side magnetic shield 50d is a place where external magnetism leaks inward, if the gap Y is in the vicinity of the gap X, the leakage The generated magnetism affects the measurement of the amount of magnetic flux by the Hall element 40.
Here, when the first side magnetic shield 50c and the second side magnetic shield 50d are arranged so that the line connecting the gap X and the line connecting the gap Y intersect at an angle of approximately 90 degrees, the gap X and the gap Y are located farthest away. Therefore, it is possible to prevent the magnetism leaking from the gap Y from affecting the measurement of the magnetic flux amount by the Hall element 40.

Further, the upper magnetic shield 50a and the lower magnetic shield 50b are larger than the inner diameter of the overall magnetic flux collecting yoke 30 formed by the first magnetic flux collecting yoke 30a and the second magnetic flux collecting yoke 30b arranged to face each other. As a structure having openings 51a and 51b each having a diameter smaller than the outer diameter, the permanent magnet 20 of the rotation angle detection sensor and a part of the first and second magnetic flux collecting yokes 30a and 30b have openings 51a and 51b. It was exposed inside.
Thereby, since the upper magnetic shield 50a and the lower magnetic shield 50b are not positioned in the vertical direction of the permanent magnet 20 where the magnetic collecting yoke 30 is not located, the upper magnetic shield 50a and the lower magnetic shield 50b are placed on the permanent magnet 20. To prevent the influence.
Further, a part of the magnetic flux collecting yoke 30 is exposed in the openings 51a and 51b, and the magnetic flux collecting yoke 30 is located closer to the permanent magnet 20 than the edges of the openings 51a and 51b. Therefore, it is possible to prevent the magnetic flux from entering the upper magnetic shield 50a and the lower magnetic shield 50b. Therefore, since the magnetic flux density of the magnetic flux collecting yoke 30 does not decrease, the output characteristics of the rotation angle detection sensor do not change.

The above embodiment has been described by taking as an example the case where the inner diameter side region of the magnet-collecting yoke 30 having a ring shape as a whole is exposed in the opening 51a of the upper magnetic shield 50a and the opening 51b of the lower magnetic shield 50b. .
However, the sizes of the openings 51a and 51b are within a range in which the rotating body 10 of the rotation angle sensor can be inserted and the upper magnetic shield 50a and the lower magnetic shield 50b do not affect the magnetism of the permanent magnet 20. These can be changed as appropriate.
Therefore, as long as this condition is satisfied, the sizes of the openings 51a and 51b can be set such that the first magnetic flux collecting yoke 30a and the second magnetic flux collecting yoke 30b are not exposed inward.

  Furthermore, in the above-described embodiment, the upper magnetic shield 50a, the lower magnetic shield 50b, the first side magnetic shield 50c, and the second side magnetic shield 50d are supported by the support members 60 and 70 arranged to face each other with the rotating body 10 interposed therebetween. Although a configuration is adopted in which they are arranged with a predetermined gap therebetween, they may be supported by a plurality of support members 60 and 70 arranged in the circumferential direction around the rotating body 10. In this case, the number of support members 60 fixed to a frame (not shown) can also be appropriately changed according to the stability of each magnetic shield 50 and the like.

It is a figure which shows the whole structure of the rotation angle detection sensor concerning an Example. It is a disassembled perspective view of the rotation angle detection sensor concerning an Example. It is a top view which expands and shows a permanent magnet. It is a disassembled perspective view of the shield of the rotation angle detection sensor concerning an Example. It is a figure which shows the whole structure of the shield of the rotation angle detection sensor concerning an Example. It is a figure which shows the state by which the shield of the rotation angle detection sensor concerning an Example is arrange | positioned by the support member. It is a figure which shows the effect | action of an Example compared with a prior art example. It is a figure which shows the effect | action of an Example compared with a prior art example. It is a figure which shows the effect | action of an Example compared with a prior art example. It is a figure which shows the whole structure of the rotation angle detection sensor of a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Rotating body 11 Magnet holding part 20 Permanent magnet 20a Magnet semicircle part 20b Magnet semicircle part 30 Magnet collection yoke 30a 1st magnetism collection yoke 30b 2nd magnetism collection yoke 40 Hall element 50 Magnetic shield 50a Upper magnetic shield 50b Lower magnetic shield 50c First side magnetic shield 50d Second side magnetic shield 51a opening 51b opening

Claims (3)

A ring-shaped permanent magnet that can rotate integrally with the object to be detected and whose magnetic poles change along the circumferential direction;
A ring-shaped yoke surrounding the outer peripheral surface of the ring-shaped permanent magnet with a certain gap;
A non-contact rotational angle detection sensor comprising a magnetic sensitive element arranged in a gap formed by dividing the ring-shaped yoke into two along a diameter line,
A ring-shaped magnetic shield surrounding the outer peripheral surface of the ring-shaped yoke with a certain gap, an upper magnetic shield arranged with a certain gap from the upper surface of the ring-shaped yoke, and a certain gap from the lower surface of the ring-shaped yoke A non-contact rotational angle detection sensor characterized in that a lower magnetic shield disposed in the space is provided apart from each other. The ring-shaped magnetic shield is divided into two along a diameter line. In the ring-shaped magnetic shield, a diameter line that divides the ring-shaped magnetic shield and a diameter line that divides the ring-shaped yoke are orthogonal to each other. The contactless rotation angle detection sensor according to claim 1, wherein the sensor is arranged as described above. 3. The upper magnetic shield and the lower magnetic shield are ring-shaped members in which openings having a diameter larger than an inner diameter of the ring-shaped yoke and smaller than an outer diameter are formed. The non-contact type rotation angle detection sensor described.

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