JP2008128752A - Noncontact type angle sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve detection of a rotation angle in accuracy even in the case of being made compact. <P>SOLUTION: A noncontact type angle sensor for detecting a rotation angle of a rotating shaft 10 includes: a pair of magnets 54, 56 arranged in above rotation displacement direction; a magnetic sensor 6 disposed between the pair of magnets 54, 56; and a main-rotor core 50 and a sub-rotor core 52 which are made of a magnetic material and attached to the rotating shaft 10. The pair of magnets 54, 56 are magnetized opposite to each other in the direction of the axial center of the rotating shaft 10. The magnetic sensor 6 detects a magnetic field between the pair of magnets 54, 56, which is varied by the main-rotor core 50 being displaced rationally. The main-rotor core 50 and the sub-rotor core 52 are positioned so as to face the pair of magnets 54, 56, and a constant space is formed between the pair of magnets 54, 56 by using a spacer 60. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a non-contact type angle sensor used for a rotating actuator used for a robot or the like.

FIG. 1A is a perspective view of a conventional non-contact angle sensor 1. As shown in FIG. 1A, a pair of substantially semicircular magnets (permanent magnets) 42 and 44 are disposed on the upper surface of the fixed core 2 that is not movable. The fixed core 2 has a disk shape and is made of a magnetic material.
In this example, the magnetic sensor 6 is disposed between the pair of magnets 42 and 44. The magnets 42 and 44 are magnetized in directions opposite to each other in the axial direction of the rotary shaft 10. In this example, the magnet 42 is magnetized on the S pole on the upper side and the N pole on the lower side, and the magnet 44 is magnetized on the N pole on the upper side and the S pole on the lower side. Note that a movable body (not shown) as a target for detecting an angle is attached to the rotating shaft 10.
The rotor core 8 is made of a magnetic material and has a substantially semicircular flat plate shape like the magnets 42 and 44. A semicircular rotor core opening 8b into which the rotary shaft 10 is fitted is provided at the center of the rotor core 8. The rotor core 8 is attached to the rotary shaft 10 so that the end of the rotary shaft 10 and the rotor core opening 8b are fitted, the plate surface thereof is perpendicular to the axis of the rotary shaft 10 and is in close proximity to the magnets 42 and 44. It is attached. A space 4a is provided between the magnet 42 and the magnet 44, and the rotating shaft 10 is attached to the space 4a.

Next, the magnetic sensor 6 will be briefly described. FIG. 1B is a perspective view of an example of the magnetic sensor 6. The magnetic sensor 6 is, for example, a Hall IC configured using a Hall element, and a magnetic sensor terminal 6a is attached. The intensity of the magnetic field passing through the top surface 6A and the bottom surface 6B of the magnetic sensor 6 is detected, and a voltage corresponding to the detected magnetic field strength is output. Briefly, the intensity α of the magnetic field from the upper surface 6A to the bottom surface 6B and the intensity β of the magnetic field from the bottom surface 6B to the upper surface 6A are detected, and a voltage corresponding to the difference between α and β is output.
The magnetic sensor 6 is arranged so as to detect a change in the magnetic field in the direction perpendicular to the plate surface of the fixed core 2, that is, in the plate thickness direction of the magnets 42 and 44. Due to the rotational motion of the rotor core 8, the magnetic field between the magnets 42 and 44 changes, and as described above, the magnetic sensor 6 outputs a voltage corresponding to the strength of the magnetic field passing through the top surface 6A and the bottom surface 6B of the magnetic sensor. Accordingly, the output voltage of the magnetic sensor 6 also changes in accordance with the change in the magnetic field strength between the magnets 42 and 44. Therefore, by obtaining the change in the output voltage of the magnetic sensor 6, the rotational motion of the rotor core 8, that is, the rotational angle of the movable body attached to the rotary shaft 10 can be detected. Details of the non-contact type angle sensor 1 are described in Patent Document 1.

  FIG. 1C is a perspective view of a non-contact type angle sensor 9 which is a modification of the non-contact type angle sensor 1. In addition, the same reference number is attached to the same functional component, the duplicate description is omitted, and the same applies to the following description. The difference from the non-contact type angle sensor 1 is that the side planes of the magnets 42 and 44 that are not opposed to the magnetic sensor 6 are closer to each other, and the center portion of the magnet 42 and the magnet 44 is engaged with the rotating shaft 10. A shaft opening 4B is provided. By providing the rotation shaft opening 4B, the rotation shaft 10 can be fitted more firmly than the non-contact type angle sensor 1, so that stable angle detection can be performed. In FIG. 1C, these magnets are indicated as 421 and 441, respectively.

  FIG. 2 is a perspective view of a non-contact type angle sensor 12 in which the non-contact type angle sensor 9 shown in FIG. 1C is downsized. In order to reduce the size of the non-contact type angle sensor 9, for example, the rotation axis with the broken lines 8a, 421a, 441a drawn in the circumferential direction described in the rotor core 8 and magnets 421, 441 in FIG. 10A in the rotor core 8, the 421A in the magnet 42, and the 441A in the magnet 44 are deleted. In FIG. 2, the miniaturized rotor core and the pair of magnets are shown as a rotor core 8 ', a magnet 42', and a magnet 44 ', respectively. Further, in order to maintain the attachment strength between the movable body (not shown) and the rotating shaft 10, the length in the longitudinal direction of the rotating shaft 10 and the diameter of the cross-sectional circle are not changed, and the fixed core 2 is not changed in this example.

FIG. 3A is a perspective view of the non-contact type angle sensor 12, but the rotating shaft 10 is omitted and is slightly enlarged for ease of explanation. FIG. 4A is a plan view of the non-contact angle sensor 12 as viewed from directly above. As shown in FIGS. 3A and 4A, a line that bisects the rotor core 8 ′ perpendicular to the upper surface 8 ′ A of the rotor core 8 ′ is a center line 8 ′ C, and this center line 8 ′ C is the center of the magnetic sensor 6. The rotation angle is 0 degree when it is at a position immediately above. Further, when the magnetic sensor 6 is viewed from directly above, the clockwise direction is a positive direction rotation, and the opposite direction to the clockwise direction is a negative direction rotation.
3B is a perspective view of the non-contact type angle sensor 12 when the rotation angle of the rotor core 8 ′ is 80 degrees, and FIG. 4B shows the non-contact type angle sensor 12 when the rotation angle of the rotor core 8 ′ is 80 degrees. It is a top view at the time of seeing from right above.
3C is a perspective view of the non-contact type angle sensor 12 when the rotation angle of the rotor core 8 ′ is −80 degrees, and FIG. 4C is a non-contact type angle when the rotation angle of the rotor core 8 ′ is −80 degrees. It is a top view at the time of seeing the sensor 12 from right above. The details of the non-contact angle sensor 12 are described in a patent application (Japanese Patent Application No. 2005-289888) which is a patent application of the same inventor and the same applicant and which has not been published.
JP 2004-354237 A

The following are two problems that the invention is trying to solve.
(1) As described above, a magnetic field is formed by the magnet 42 'and the magnet 44'. Accordingly, a magnetic field passes through the rotor core 8 of the non-contact type angle sensor 12, and a magnetic saturation phenomenon occurs in a certain portion of the rotor core 8.
FIG. 5A is a diagram showing that a magnetic saturation phenomenon occurs in a certain portion (shaded portion) of the rotor core 8 in the non-contact type angle sensor 1 on the plane 8A when the rotor core 8 is viewed from directly above. As shown in FIG. 5A, when the rotor core 8 has a semi-doughnut shape, a magnetic saturation phenomenon occurs in a region R indicated by hatching that is substantially the central portion of the rotor core 8. In the following description, a region where the magnetic saturation phenomenon occurs is referred to as a magnetic saturation region.
FIG. 5B is a diagram showing a magnetic saturation region R ′ (shaded portion) of the rotor core 8 ′ in the plane 8′A when the rotor core 8 ′ is viewed from directly above. As shown in FIG. 5B, the magnetic saturation region R ′ of the miniaturized rotor core 8 ′ is enlarged. The reason for this will be described below.
As described above, the non-contact type angle sensor 12 is a miniaturized version of the non-contact type angle sensor 9. Therefore, the rotor core 8 ′ is a miniaturized version of the rotor core 8, and the magnets 42 ′ and 44 ′ are miniaturized versions of the magnets 42 and 44, respectively.

Generally, when a magnet is downsized, the magnetic force of the magnet, that is, the strength of the magnetic field is reduced. As described above, the magnetic sensor 6 outputs a voltage corresponding to the strength of the magnetic field. Accordingly, when the strength of the magnetic field generated in the magnets 42 ′ and 44 ′ is smaller than the strength of the magnetic field generated in the magnets 42 and 44, the accuracy of the magnetic sensor 6 is degraded. Therefore, it is desirable that the strength of the magnetic field generated in the magnets 42 ′ and 44 ′ is substantially equal to the strength of the magnetic field generated in the magnets 42 and 44.
The fact that the magnetic field strengths are substantially equal means that the number of magnetic fluxes passing through the rotor core 8 ′ is substantially equal to the number of magnetic fluxes passing through the rotor core 8, and the cross-sectional area of the rotor core 8 ′ is smaller than the cross-sectional area of the rotor core 8. . That is, the magnetic flux density is higher in the rotor core 8 ′. Therefore, the size of the magnetic saturation region R ′ of the rotor core 8 ′ is larger than that of the magnetic saturation region R of the rotor core 8.
When the magnetic saturation region is enlarged, a change in the magnetic flux density detected by the magnetic sensor 6 is swelled, the detection accuracy is lowered, and output dullness at both ends of the detection angle range becomes conspicuous.

(2) When the rotation angle of the rotor core 8 ′ is 0 degree, the side plane above the magnet 44 ′ of the rotor core 8 ′ is 8′B, and the side plane above the magnet 42 ′ of the rotor core 8 ′ is 8′D. FIG. 6A is a diagram showing that the magnetic flux group 30 from the magnet 44 ′ enters the side plane 8′B and exits from the side plane 8′D.
Further, as shown in FIGS. 7A and 7B, a point B and a point B ′ are end points, and a curve tracing the magnet 44 ′ and the magnet 42 ′ (shown by a broken line) is a curve BB ′. FIG. 7B shows a case where the cross section of the curve BB ′ of the rotor core 8 ′, the magnet 42 ′, and the magnet 44 ′ is developed linearly and viewed from the terminal 6 a side of the magnetic sensor 6 when the rotation angle of the rotor core 8 ′ is 0 degree. It is the figure which showed the magnetic field in the case of. As shown in FIGS. 6A and 7B, the magnetic flux group 30 enters from the side plane 8′B, exits from the side plane 8′D on the magnet 42 ′ side, and proceeds to the S pole side of the magnet 42 ′.
As shown in FIG. 7B, not only the magnetic flux group 32 of the magnetic field formed by overlapping the rotor core 8 ′, the magnet 42 ′ and the magnet 44 ′ but also the magnetic flux group 30 entering from the side plane 8′B As a result, the magnetic flux density of the rotor core 8 ′ increases and the magnetic saturation region R ′ expands. Therefore, the accuracy of the magnetic sensor 6 deteriorates when the rotor core 8 ′ is at a position near 0 degrees.

FIG. 6B is a diagram showing the movement of magnetic flux near the side plane 8′B and the side plane 8′D of the rotor core 8 ′ when the rotation angle of the rotor core 8 ′ is 80 degrees. FIG. 7C is a diagram showing the curve BB ′ in the plan view of FIG. 4B (a plan view of the non-contact angle sensor when the rotation angle of the rotor core 8 ′ is 80 degrees). is there.
FIG. 7D is a diagram illustrating a magnetic field by developing a section of a curve BB ′ of the rotor core 8 ′, the magnet 42 ′, and the magnet 44 ′ linearly when the rotation angle of the rotor core 8 ′ is 80 degrees. In FIG. 7D, the description of magnetic flux that is not related to the magnetic flux shown in FIG. 7C is omitted. As shown in FIGS. 6B and 7D, a magnetic flux group 34 indicated by a one-dot chain line enters from the side plane 8′D. The magnetic flux group 34 cancels the magnetic field between the magnets 42 'and 44'. Therefore, the accuracy of the magnetic sensor 6 also deteriorates when the rotor core 8 'is located near 80 degrees.
An object of the present invention is to prevent intrusion of a magnet from a side plane and improve accuracy.

  The non-contact type angle sensor of the present invention includes a fixed part and a movable part, and detects the rotation angle of the rotating shaft. The fixed part includes a pair of magnets arranged in the rotational displacement direction and a magnetic sensor arranged between the pair of magnets. The movable part has a pair of rotor cores made of a magnetic material attached to a rotating shaft. The pair of magnets are magnetized in directions opposite to each other in the axial direction of the rotating shaft. The magnetic sensor detects a magnetic field between the pair of magnets that is changed by the rotationally displaced rotor core. The pair of rotor cores are positioned to face the pair of magnets, and a certain space is provided between the pair of magnets. Moreover, what is necessary is just to design the space | interval of a pair of said rotor core so that it may adapt to the detection accuracy calculated | required by a non-contact-type angle sensor. Further, a plurality of the magnetic sensors may be arranged.

With the above configuration, the conventional rotor core 8 ′ is used as a main rotor core, and a sub-rotor core made of the same material as the main rotor core is further added.
A constant interval is provided between the main rotor core and the sub-rotor core. By providing this interval, a magnetic flux group from the magnet is prevented from entering from both side planes of the main rotor core. Therefore, when the main rotor core is at the 0 degree position, the number of magnetic fluxes passing through the main rotor core can be reduced, and the magnetic saturation region can be reduced. Therefore, the accuracy of the magnetic sensor can be improved.
In addition, when the main rotor core is at a position of 80 degrees, the magnetic flux group is prevented from entering from the side plane, so that the magnetic flux group of the magnetic field generated between the magnets is prevented from canceling and the accuracy of the magnetic sensor is improved. I can do it.
As a result, highly accurate angle detection is possible even if the entire non-contact type angle sensor is downsized.

FIG. 8 is a perspective view of an embodiment of the non-contact type angle sensor 51 of the present invention, and FIG. 9 is a plan view of the non-contact type angle sensor 51 of the present invention viewed from the right side when viewed from the magnetic sensor 6. FIG. 10 is an exploded view of the non-contact type angle sensor 51 of the present invention, and FIG. 11 is a perspective view in which the rotating shaft 10 of the non-contact type angle sensor 51 of the present invention and the spacer 60 described below are omitted. .
In the non-contact type magnetic sensor according to the present invention, the fixed portion includes at least a pair of magnets 54 and 56, and a magnetic sensor 6 disposed between the magnet 54 and the magnet 56. The fixed core 2 is also configured.
Further, the movable portion is composed of at least a pair of rotor cores that are a main rotor core 50 and a sub-rotor core 52.

As shown in FIGS. 8, 9, and 10, a pair of magnets 54 and 56 are disposed on the upper surface of the fixed core 2. The pair of magnets 54 and 56 are magnetized in directions opposite to each other in the axial direction of the rotary shaft 10. In this embodiment, the upper side of the magnet 54 is the S pole, the lower side is the N pole, the upper side of the magnet 56 is the N pole, and the lower side is the S pole (see FIG. 10). The pair of magnets 54 and 56 are bonded magnets, and powders of samarium cobalt and ferrite are used as permanent magnet powders mixed with the resin. In this embodiment, the magnets 54 and 56 have an arc shape centered on the rotation axis of the rotation shaft 10 and are arranged in a circumferential direction centering on the rotation axis.
The main rotor core 50 and the sub-rotor core 52 are arranged on the plane perpendicular to the rotation shaft 10 with a constant interval. When the main rotor core 50 is rotationally displaced, the sub-rotor core 52 is also rotationally displaced on the plane with the constant interval being provided. In this embodiment, the main rotor core 50 and the sub-rotor core 52 have an arc shape centered on the rotational axis of the rotary shaft 10 and are arranged in a circumferential direction centered on the rotational axis. The main rotor core 50 and the sub rotor core 52 are made of a soft magnetic material, and silicon steel or the like is used as the material.

The main rotor core 50 and the sub-rotor core 52 are disposed so as to face the magnet 54 and the magnet 56, and between the pair of rotor cores (the main rotor core 50 and the sub-rotor core 52) and the pair of magnets (the magnet 54 and the magnet 56). Has a certain space. As a method of providing this space, as shown in FIG. 8, FIG. 9, and FIG. 10, a spacer 60 that is a non-magnetic material may be provided, and a pair of rotor cores are provided so that a space is provided by a mounting portion (not shown). Also good. The details of the spacer 60 are described in the above-mentioned patent application (Japanese Patent Application No. 2005-289888).
In this embodiment, the rotary shaft 10 is cylindrical. As shown in FIGS. 8 to 10, the rotary shaft 10, the main rotor core 50, and the sub-rotor core 52 may be fitted through a supporter 62 that is a nonmagnetic material, or directly without using the supporter 62. You may make it fit. When the supporter 62 is used, the thickness of the rotating shaft 10 can be appropriately changed by adjusting the diameter of the rotating shaft hole 62a (see FIG. 10) to be fitted with the rotating shaft 10.
The magnetic sensor 6 is disposed between the magnet 54 and the magnet 56. The magnetic sensor 6 detects the magnetic field between the magnet 54 and the magnet 56 that are changed by the main rotor core 50 and the sub-rotor core 52 that are rotationally displaced, and outputs a voltage corresponding to the detected magnetic field. Therefore, the output voltage of the magnetic sensor 6 changes according to the change in the magnetic field strength, and as a result, the rotational motion of the main rotor core 50, that is, the rotational angle of the movable body attached to the rotary shaft 10 can be detected.

In the following description, a line that bisects the main rotor core 50 perpendicular to the upper surface of the main rotor core 50 is defined as a center line 50C, and the center rotor core 50C is located at a position directly above the center of the magnetic sensor 6. The rotation angle of 50 is assumed to be 0 degree. Further, when viewed from directly above, the rotation in the clockwise direction is defined as the positive rotation, and the rotation in the opposite direction to the clockwise is defined as the negative rotation.
FIG. 12A is a perspective view of the non-contact type angle sensor 51 when the rotation angle of the main rotor core 50 is 0 degree, and FIG. 13A shows the non-contact type angle sensor 51 when the rotation angle of the main rotor core 50 is 0 degree. It is a top view at the time of seeing from the top.
FIG. 12B is a perspective view of the non-contact type angle sensor 51 when the rotation angle of the main rotor core 50 is 80 degrees, and FIG. 13B is a perspective view of the non-contact type angle sensor 51 when the rotation angle of the main rotor core 50 is 80 degrees. It is a top view at the time of seeing from the top.
12C is a perspective view of the non-contact type angle sensor 51 when the rotation angle of the main rotor core 50 is −80 degrees, and FIG. 13C is a non-contact type angle sensor 51 when the rotation angle of the main rotor core 50 is −80 degrees. It is a top view at the time of seeing from right above. The angle detected by the non-contact type angle sensor 51 of the present invention is in the range of ± 80 degrees. In FIG. 12 and FIG. 13, the rotating shaft 10 and the spacer 60 are omitted for simplification of description.

Further, as shown in FIGS. 13A to 13C, a point B and a point B ′ are end points, and a curve (indicated by a broken line) tracing the magnet 56 and the magnet 54 is a curve BB ′. FIG. 14 shows a cross section of the curve BB ′ of the main rotor core 50, the sub-rotor core 52, the magnet 54, and the magnet 56 linearly developed when the rotation angle of the main rotor core 50 is 0 degree, and the terminal 6a side of the magnetic flux sensor 6 It is the figure which showed the main magnetic field seeing from. 15 and 16, which will be described below, are illustrated in the same manner as in FIG. 14, and a magnetic field that is not related to the description is omitted.
FIG. 15A is a diagram illustrating a main magnetic field when the rotation angle of the main rotor core 50 is 0 degrees. As shown in FIG. 15A, the strength of the magnetic field passing from the top surface of the magnetic sensor 6 is equal to the strength of the magnetic field passing from the bottom surface of the magnetic sensor 6, that is, substantially zero.
FIG. 15B is a diagram illustrating main magnetic fields when the rotation angle of the main rotor core 50 is 80 degrees. In this case, the intensity of the magnetic field passing from the bottom surface of the magnetic sensor 6 is maximized.
FIG. 15C is a diagram illustrating main magnetic fields when the rotation angle of the main rotor core 50 is −80 degrees. In this case, the intensity of the magnetic field passing from the upper surface of the magnetic sensor 6 is maximized.

  As described above, when the sub-rotor core 52 is not provided as in the conventional non-contact type angle sensor 51, that is, when the number of the main rotor core 50 is one, the extra magnetic flux group 30 from the side plane 52B of the main rotor core 50. (See FIGS. 6A and 7B). However, as shown in FIG. 15A, by providing the sub-rotor core 52 with a certain distance r from the main rotor core 50, the extra magnetic flux group 30 does not enter from the side plane 50B of the main rotor core 50, The excess magnetic flux group 30 enters from the bottom surface 52 </ b> A of the sub-rotor core 52. As a result, an extra magnetic flux group does not enter the main rotor core 50, and the magnetic saturation region R1 of the main rotor core 50 can be reduced as compared with the magnetic saturation region R ′ of the conventional rotor core. As a result, a decrease in output change at the end of the detection range can be prevented, and the angle detection accuracy of the non-contact type angle sensor 51 is improved.

Further, in the conventional non-contact angle sensor 51 in which the sub-rotor core 52 is not provided, as described above, when the rotation angle of the rotor core 8 ′ is at the position of 80 degrees, the function of the magnetic sensor 6 is adversely affected. The magnetic flux group 34 entered from the side plane 8′D (see FIGS. 6B and 7D).
However, as shown in FIG. 15B, when the rotation angle of the main rotor core 50 is 80 degrees, by providing the sub-rotor core 52 with a certain distance r from the main rotor core 50, the magnetic flux group 34 is separated from the side plane 50D. Since it does not enter, the magnetic sensor 6 is not adversely affected.
That is, in the present invention, in addition to the main rotor core 50, the sub-rotor core 52 is provided at a constant interval r, thereby preventing magnetic flux from entering from the side plane of the main rotor core 50, and the magnetic sensor 6 As a result, the angle detection of the non-contact type angle sensor 51 is also improved.

Next, the distance r provided between the main rotor core 50 and the sub rotor core 52 will be described.
FIG. 16 is a diagram showing a magnetic field when the interval r is longer than a predetermined value when the rotation angle of the main rotor core 50 is 0 degrees. In this case, the magnetic flux group 30 enters the main rotor core 50 from the side plane 50B, and as a result, the conventional problem described above cannot be solved. That is, the accuracy of the magnetic sensor 6 is deteriorated.
FIG. 17 shows a case where the interval r is extremely shorter than a predetermined value when the rotation angle of the main rotor core 50 is 0 degree, or the interval r is 0 and the main rotor core 50 and the sub-rotor core 52 are connected. It is the figure which showed no magnetic field. In this case, the magnetic flux passes through the side planes of the main rotor core 50 and the sub-rotor core 52, and functions as if the main rotor core 50 and the sub-rotor core 52 are integrated. In this case, even if the main rotor core 50 rotates, the state of the magnetic flux hardly changes. Therefore, the change in the output voltage of the magnetic sensor 6 becomes small, and as a result, the detection accuracy of the rotation angle also decreases. Therefore, it is desirable to design the magnetic flux entering from the side plane 50B so that the interval r is as wide as possible without degrading the required angle detection accuracy. That is, the interval r is a design item required from detection accuracy. A specific value of the interval r will also be described in the following experimental results.

As a modification of this embodiment, a plurality of magnetic sensors 6 can be provided. FIG. 18 is a perspective view of the non-contact angle sensor 51 when two magnetic sensors are provided, that is, when the magnetic sensor 6 and the magnetic sensor 6 ′ are provided. 6′a represents a terminal of the magnetic sensor 6 ′.
Further, regarding the installation of three or more magnetic sensors, a plurality of desired magnetic sensors are built in the magnetic sensor 6 or the magnetic sensor 6 ′, as will be described with reference to FIG.
The compensation can be improved by increasing the number of magnetic sensors. In other words, even if one magnetic sensor breaks down and the output voltage value of the failed magnetic sensor shows an abnormal value compared to the output voltage value of the other magnetic sensor, the failed magnetic sensor is discovered early I can do it.
In addition, the non-contact angle sensor 51 can always be operated normally by switching to a normally operating magnetic sensor when the magnetic sensor fails.
In addition, a more accurate output voltage value can be obtained, for example, by obtaining an average value of voltage values output from a plurality of magnetic sensors.
Although the non-contact type angle sensor 51 using the fixed core 2 has been described above, the non-contact type angle sensor 51 of the present invention can be implemented even if the fixed core 2 is omitted. Further, the shapes of the main rotor core 50, the sub-rotor core 52, the magnet 54, the magnet 56, and the like are not limited to the shapes described above.

Experimental Results Hereinafter, experimental results showing that the non-contact angle sensor 51 of the present invention is superior to the conventional one will be described.
The dimension conditions of the non-contact type angle sensor 51 used in this experiment will be described. FIG. 19 is a plan view showing the dimensions of each part of the non-contact type angle sensor 51 used in this experiment as seen from directly above. FIG. 20 is a side view of the non-contact type angle sensor 51 used in this experiment. It is the top view which showed the dimension of each part seeing from.

  As shown in FIGS. 19 and 20, the outer diameter of the fixed core 2 is set to 12 mm. The direction parallel to the upper surface of the fixed core 2 and the terminal direction of the magnetic sensor 6 is the x-axis direction, and the direction parallel to the upper surface of the fixed core 2 and perpendicular to the x-axis direction is the y-axis direction. The length in the x-axis direction of the circle formed by the outer peripheral portions of the magnets 54 and 56 is 10 mm, the length in the y-axis direction is 9.8 mm, and the length in the x-axis direction of the circle formed by the inner peripheral portions of the magnets 54 and 56 Is 6 mm, and the length in the y-axis direction is 6.2 mm. The fixed core 2 is provided with a thickness of 0.5 mm, the magnets 54 and 56 are provided with a thickness of 1.0 mm, the main rotor core 50 and the sub-rotor core 52 are provided with a thickness of 1.0 mm, and a spacer 60 (not shown). The thickness of the space is 0.5 mm. When the non-contact angle sensor 51 has these dimensions, the interval r provided between the main rotor core 50 and the sub-rotor core 52 described above is preferably 1 mm.

The material of the fixed core 2 is electromagnetic soft iron, the magnet material is a coercive force Hc = 360 KA / m, the main rotor core 50 and the sub-rotor core 52 are electromagnetic soft iron, and the arc angle formed by the main rotor core 50 is 200. Degree. When the non-contact type angle sensor 51 has the above dimensions, the arc angle formed by the main rotor core 50 is preferably 200 degrees, and the arc angle formed by the sub-rotor core 52 is preferably about 160 degrees.
In addition, three types of conventional non-contact angle sensors 12 described above were used as objects to be compared. In these three types of non-contact angle sensors 12, the angles of arcs formed by the rotor core 8 '(hereinafter referred to as rotor core angles) are 180 degrees, 200 degrees, and 220 degrees, respectively.

FIG. 21 shows the relationship between the rotation angle and the magnetic flux density detected by the magnetic sensor 6 when the main rotor core 50 (rotor core 8 ′) is at the position of the rotation angle. The horizontal axis is the rotation angle, and the vertical axis is It is a graph showing magnetic flux density. The horizontal axis represents the rotation angle, and the vertical axis represents the magnetic flux density. Further, the non-contact type angle sensor 51 of the present invention is represented by the thickest solid line, and the non-contact type angle sensor 12 having the rotor core angles of 180 degrees, 200 degrees, and 220 degrees is represented by a broken line, an alternate long and short dash line, and a thin solid line, respectively. The The same applies to FIG. 21 described below.
As described above, a voltage is output according to the intensity of the magnetic field detected by the magnetic sensor 6, and the rotation angle of the main rotor core 50 (rotor core 8 ′) is obtained from the output voltage. That is, if the magnetic flux density proportional to the rotation angle can be detected, the non-contact angle sensor 51 can accurately detect the angle. Therefore, in the graph shown in FIG. 20, a non-contact type angle sensor having accurate linearity can perform accurate angle detection. As can be seen from FIG. 21, the non-contact angle sensor 51 of the present invention has the most accurate linearity and is more accurate than the other conventional non-contact angle sensors 12.

FIG. 22 is a graph showing the relationship between the rotation angle and deviation of the main rotor core 50 (rotor core 8 ′), with the horizontal axis representing the rotation angle and the vertical axis representing the deviation. Here, the deviation will be described with reference to FIG. As shown in FIG. 23, the deviation means the main rotor core 50 or the sub-rotor core 8 ′ using the graph A indicated by the arbitrary non-contact type angle sensor shown in FIG. 21 and the graph B having completely linearity. The magnetic flux densities of graphs A and B at an arbitrary rotation angle ω are yA and yB, and Δy = yA−yB. Further, the absolute difference between the magnetic flux density when the rotation angle of the main rotor core 50 (rotor core 8 ′) is 80 degrees and the magnetic flux density when the rotation angle of the main rotor core 50 (rotor core 8 ′) is −80 degrees. When the value is y, the deviation D at the rotation angle ω is expressed by D = | Δy | / y.
As apparent from FIG. 22, the deviation value of the non-contact type angle sensor 51 of the present invention is smaller than the deviation value of the other conventional non-contact type angle sensor 12 and has linearity. ing. Thereby, it will be understood that the non-contact type angle sensor 51 of the present invention is superior to other conventional non-contact type angle sensors 12.

FIG. 1A is a perspective view of a conventional non-contact type angle sensor 1, FIG. 1B is a perspective view of a magnetic sensor 6, and FIG. 1C is a perspective view of a non-contact type angle sensor 9. The perspective view of the non-contact type angle sensor 12. FIG. FIG. 3A is a perspective view in which the rotation shaft 10 of the non-contact type angle sensor 12 is omitted, FIG. 3A shows a case where the rotation angle of the rotor core 8 ′ is 0 degree, and FIG. 3B shows a case where the rotation angle of the rotor core 8 ′ is 80 degrees. Is the case where the rotation angle of the rotor core 8 'is -80 degrees. 4A is a plan view of the non-contact type angle sensor 12 as viewed from directly above, FIG. 4A shows a case where the rotation angle of the rotor core 8 ′ is 0 degree, FIG. 4B shows a case where the rotation angle of the rotor core 8 ′ is 80 degrees, and FIG. This is a case where the rotation angle of the rotor core 8 ′ is −80 degrees. FIG. 5A is a plan view of the rotor core 8 or the rotor core 8 ′ viewed from directly above, showing that a magnetic saturation phenomenon occurs in a certain portion (shaded portion), FIG. 5A is a diagram showing the rotor core 8, and FIG. It is a figure shown about rotor core 8 '. 6A is a diagram showing that the magnetic flux group 30 from the magnet 44 ′ enters the side plane 8′B on the magnet 44 ′ side of the rotor core 8 ′ when the rotation angle of the rotor core 8 ′ is 0 degree, FIG. These are figures which showed the motion of the magnetic flux of side surface 8'B vicinity and side surface 8'D vicinity of rotor core 8 'when the rotation angle of rotor core 8' is 80 degree | times. FIG. 7A is a diagram in which a curve BB ′ is attached to a plan view of the non-contact type angle sensor viewed from directly above when the rotation angle of the rotor core 8 ′ is 0 degree, and FIG. 7B is a diagram in which the rotation angle of the rotor core 8 ′ is 0 degree. FIG. 7C is a diagram showing a magnetic field by linearly developing the cross section of the curve BB ′ of the rotor core 8 ′, the magnet 42 ′, and the magnet 44 ′ in the case of FIG. FIG. 7D is a plan view of the contact-type angle sensor as viewed from directly above, and FIG. 7D is a curve BB of the rotor core 8 ′, the magnet 42 ′, and the magnet 44 ′ when the rotation angle of the rotor core 8 ′ is 80 degrees. It is the figure which expand | deployed the cross section of 'to linear form, and showed the magnetic field. The perspective view of the non-contact type angle sensor 51 of this invention. In the non-contact type angle sensor 51 of this invention, it is the top view seen from the right side seeing from the magnetic sensor 6. FIG. The figure which decomposed | disassembled the non-contact-type angle sensor 51 of this invention. The perspective view which abbreviate | omitted the rotating shaft 10 and the spacer 60 of the non-contact-type angle sensor 51 of this invention. FIG. 12A is a perspective view in which the rotation shaft 10 and the spacer 60 of the non-contact type angle sensor 51 of the present invention are omitted. FIG. 12A shows a case where the rotation angle of the main rotor core 50 is 0 degree, and FIG. In the case of degrees, FIG. 12C shows a case where the rotation angle of the main rotor core 50 is −80 degrees. FIG. 13A is a plan view of the non-contact type angle sensor 51 of the present invention as viewed from directly above, and a curve BB ′ is attached. FIG. 13A shows a case where the rotation angle of the main rotor core 50 is 0 degree, and FIG. When the rotation angle is 80 degrees, FIG. 13C shows the case where the rotation angle of the main rotor core 50 is −80 degrees. The figure which showed the main magnetic field by developing the cross section of curve BB 'of the main rotor core 50, the subrotor core 52, the magnet 54, and the magnet 56 linearly when the rotation angle of the main rotor core 50 is 0 degree | times. FIG. 15A is a diagram illustrating a main magnetic field by developing a section of a curve BB ′ of the main rotor core 50, the sub rotor core 52, the magnet 54, and the magnet 56 in a straight line, and FIG. 15B shows a case where the rotation angle of the main rotor core 50 is 80 degrees, and FIG. 15C shows a case where the rotation angle of the main rotor core 50 is −80 degrees. The figure which showed the main magnetic field at the time of providing the space | interval r of the main rotor core and the subrotor core 52 longer than predetermined value, when the rotation angle of the main rotor core 50 is 0 degree | times. The figure which showed the main magnetic field in case the rotation angle of the main rotor core 50 is 0 degree | times, and the space | interval r of the main rotor core and the subrotor core 52 is very short, or is zero. The perspective view at the time of providing the two magnetic sensors 6 in the non-contact-type angle sensor 51 of this invention. The top view which described the dimension of each part seeing the non-contact type angle sensor 51 of this invention used in experiment from right above. The top view which showed the dimension of each part seeing the non-contact type angle sensor 51 used in experiment from the side. 6 is a graph showing the relationship between the rotation angle of the main rotor core 50 (rotor core 8 ′) and the magnetic flux density detected by the magnetic sensor 6 in the non-contact angle sensor 51 of the present invention and the conventional non-contact angle sensor. The graph which shows the relationship between the rotation angle of the main rotor core 50 (rotor core 8 '), and deviation in the non-contact type angle sensor 51 of this invention and the conventional non-contact type angle sensor. A graph for explaining the deviation.

Claims (4)

It is a non-contact type angle sensor that consists of a fixed part and a movable part and detects the rotation angle of the rotating shaft,
The fixed portion includes a pair of magnets arranged in the rotational displacement direction, and
A magnetic sensor disposed between the pair of magnets,
The movable part has a pair of rotor cores made of a magnetic material attached to a rotating shaft,
The pair of magnets are magnetized in opposite directions in the axial direction of the rotating shaft,
The magnetic sensor detects a magnetic field changed by the rotor core that is rotationally displaced,
The pair of rotor cores are positioned so as to face the pair of magnets, and a fixed space is provided between the pair of magnets. The non-contact type angle sensor according to claim 1,
The non-contact angle sensor, wherein the distance between the pair of rotor cores is within a range that does not deteriorate the detection accuracy required for the non-contact angle sensor. The non-contact type angle sensor according to claim 1 or 2,
A non-contact angle sensor, wherein a plurality of the magnetic sensors are arranged. The non-contact type angle sensor according to claim 1,
The non-contact type angle sensor, wherein the space is provided by a spacer.

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