JP2007309759A - Rotation sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotation sensor having constantly stable output characteristics without being affected by wobbling caused by ease of assembly and component tolerance. <P>SOLUTION: The rotation sensor comprises a rotor under measurement 10 which rotates about a specific rotational center axis, an exciting coil 20 which is fixedly arranged independently of the rotor under measurement so that it surrounds the rotor under measurement, has a center axis which nearly coincides with the rotational center axis of the rotor under measurement, and is rotatably held by the rotor under measurement directly or through a bearing member, a stator shield 30 which is fixedly arranged around the exciting coil independently of the rotation of the rotor under measurement so that it surrounds the exciting coil by a predetermined angle in the circumferential direction, and a rotor shield 40 which is attached to the rotor under measurement and rotates with the rotation of the rotor under measurement. The area of the rotor shield which crosses the magnetic flux from the exciting coil to the stator shield can be changed in accordance with the rotation of the rotor under measurement. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a rotation sensor that is attached to a rotating body and used to detect the rotation angle of the rotating body.

  For example, a so-called rotation sensor is used to detect a rotation angle of a handle attached to a rotating shaft such as a steering shaft of an automobile and integrated with the shaft.

  As an example of such a rotation sensor, one in which a fixed core is disposed opposite to a rotor at a predetermined interval is known (see, for example, Patent Document 1).

  As shown in Patent Document 1, this rotation sensor is attached to a predetermined position in the axial direction of a rotating shaft, and includes a rotor having a sensing portion whose width changes along the circumferential direction, an excitation coil, and an insulating magnetic material. And having a core for holding an exciting coil, attached to a fixed member, and connected to a fixed core and an exciting coil that are opposed to the rotor at a predetermined interval in the axial direction of the shaft, and oscillate at a specific frequency. Oscillating means for transmitting a signal is included.

  The rotor includes a rotor mounting portion made of an insulating magnetic material or an insulating resin material and a sensing portion that is connected to the rotor via a stay and has a width that continuously changes in the circumferential direction. The sensing part is made of a conductive metal and has a narrow part with the smallest width in the circumferential direction of 360 degrees and a wide part with the largest width on the opposite side in the radial direction. Then, the sensing width changes in one cycle per 360 degrees in the circumferential direction, and an eddy current having a magnitude corresponding to the width accompanying rotation is induced by the alternating magnetic field on the surface of the sensing unit. The impedance of fluctuates.

Then, using the rotation sensor having such a configuration, the rotor rotation angle is detected by utilizing the impedance fluctuation of the exciting coil accompanying the generation of the eddy current.
JP 2003-202240 A (page 4-5, FIG. 1)

  A rotor having a sensing portion attached at a predetermined position in the axial direction of the rotating shaft and having a width varying along the circumferential direction, an excitation coil, and a core formed of an insulating magnetic material and holding the excitation coil. According to a rotation sensor having a configuration including a fixed core and an excitation coil that are mounted on a fixed member and are opposed to the rotor with an interval in the axial direction of the shaft, the rotation sensor is assembled. Because of ease of use and variations in component tolerances, if priority is given to assemblyability or allowance of component tolerances to some extent, there will be a backlash in the radial direction of the coil relative to the sensing part that rotates together with the shaft. The variation in detection output characteristics increases.

  An object of the present invention is to provide a rotation sensor that always has stable output characteristics without being affected by looseness due to ease of assembly or component tolerance.

In order to solve the above-mentioned problem, the rotation sensor according to the present invention is:
A rotating body to be measured that rotates about a specific rotation center axis;
The rotating body to be measured is fixedly arranged independently of the rotating body to be measured so as to surround the rotating body to be measured, and has a center axis that approximately matches the rotation center axis of the rotating body to be measured and is directly or first An exciting coil that is rotatably held by the rotating body to be measured via a bearing member;
A stator shield fixedly arranged independently of the rotation of the rotating body for measurement so as to surround the excitation coil by a predetermined angle in the circumferential direction of the excitation coil;
A rotor shield that is attached to the rotating body for measurement and rotates together with the rotation of the rotating body for measurement;
The area of the rotor shield that crosses the magnetic flux from the exciting coil to the stator shield is changed according to the rotation of the rotating body to be measured.

  According to this rotation sensor, the rotation center axis of the rotating body to be measured and the excitation coil are rotatably held directly or via a bearing member, the center axis coincides, and the magnetic flux from the excitation coil to the stator shield is crossed. Since the area of the rotor shield changes according to the rotation of the rotating body to be measured, the rotation sensor has always stable output characteristics without being affected by looseness due to ease of assembly and component tolerances. can do.

Moreover, the rotation sensor according to claim 2 of the present invention is the rotation sensor according to claim 1,
The rotating body for measurement consists of a shaft,
The excitation coil has a cylindrical body,
The stator shield is a partial cylindrical body having an arc shape when viewed from the rotational center axis direction of the rotating body to be measured, and surrounds the excitation coil around a predetermined angle in the circumferential direction and coincides with the rotational center axis line. It has a central axis of curvature of the arc,
The rotor shield is provided at at least one end of the shaft, and is composed of a partial disk formed at a predetermined angle in the circumferential direction.

  Since the rotating body to be measured, the excitation coil, the stator shield, and the rotor shield have such specific shapes, the rotation center axis of the rotating body to be measured and the excitation coil can be rotated directly or via a bearing member. And the center axis is easy to match, and the area of the rotor shield that crosses the magnetic flux from the exciting coil to the stator shield is easily changed according to the rotation of the rotating body to be measured. Stable output characteristics can always be obtained without being affected by backlash.

Moreover, the rotation sensor according to claim 3 of the present invention is the rotation sensor according to claim 1 or 2,
The stator shield is held by the exciting coil via a spacer.

  By arranging the stator shield in this way, the rotation center axis of the rotating body to be measured, the center axis of the excitation coil, and the center axis of curvature of the stator shield match, and cross the magnetic flux from the excitation coil to the stator shield. The area of the rotor shield is likely to change according to the rotation of the rotating body to be measured, and stable output characteristics can be obtained constantly without being affected by looseness due to ease of assembly and component tolerances.

  According to the present invention, it is possible to provide a rotation sensor that always has stable output characteristics without being affected by looseness due to ease of assembly or component tolerance.

  Hereinafter, a rotation sensor 1 according to an embodiment of the present invention will be described with reference to the drawings. In this embodiment, the rotation sensor is attached to the suspension arm with respect to a device for detecting the height of the automobile and the inclination of the vehicle body, and the vehicle height and the inclination of the vehicle body are detected by converting the vertical movement of the suspension arm into a rotation angle. Therefore, a case where a rotation sensor is used will be described.

  As shown in FIG. 1, the rotation sensor 1 includes, for example, a shaft 10 that forms a rotating body to be measured that is attached in series to a suspension arm shaft portion of an automobile, and the shaft 10 is spaced apart from the shaft 10 by a predetermined interval. An excitation coil 20 fixedly arranged independently of the rotation of the shaft 10 so as to surround it, a stator shield 30 surrounding the excitation coil 20 with a predetermined interval in the circumferential direction of the excitation coil 20, and A rotor shield 40 that is attached to the shaft 10 and rotates with the rotation of the shaft 10 is provided. The excitation coil 20 has a center axis CL2 that coincides with the rotation center axis CL1 of the shaft 10, and is fixed to a case of the rotation sensor 1 that is not shown in detail here, for example, independently of the rotation of the shaft 10. Has been. That is, each component shown in FIG. 1 is covered with a case made of a material that is not affected by external magnetism, and the shaft 10 is connected to the suspension arm shaft portion outside the case, and the suspension arm shaft portion rotates. At the same time, the inductance of the exciting coil 20 changes.

  The area of the rotor shield 40 that crosses the magnetic flux from the exciting coil 20 to the stator shield 30 changes according to the rotation of the shaft 10.

  The shaft 10 is made of, for example, iron, has a cylindrical shape, and semicircular cutout step portions 11 are formed at both ends, and the diameter direction end face 41 of the rotor shield 40 is formed in each cutout step portion 11. (See FIG. 2) are fixed against each other.

  The exciting coil 20 is wound around a coil holder that is rotatably held with respect to the outer periphery of the shaft in the circumferential direction of the shaft 10, and a large number of conducting wires are wound around the coil holder, and the outer shape forms a cylindrical body. As a result, the shaft 10 rotates inside the excitation coil 20 while the center axis of the excitation coil 20 matches the rotation center axis of the shaft 10 as described above. In FIG. 1, the gap between the shaft 10 and the excitation coil 20 is drawn larger, but in actuality, this gap is reduced, and the coil holder of the excitation coil 20 serves as a bearing member to the shaft 10. So that it can be rotated.

  That is, due to the function of the bearing member, the rotation center axis CL1 of the shaft 10 and the center axis CL2 of the exciting coil 20 always coincide with each other during the rotation of the shaft 10. Instead of providing the coil holder of the exciting coil 20 as a bearing member in this way, the exciting coil 20 itself is rotatably held on the shaft 10 by impregnating or applying a lubricating substance on the inner diameter side thereof. You may let them. Further, a bearing member may be interposed in the gap with the shaft 10 separately from the coil holder. In this case, various bearing members such as a ball bearing, a roller bearing, a resin bush, a metal bush, and a material impregnated with a lubricating substance can be applied.

  The stator shield 30 is made of, for example, iron, and is formed of a half-divided cylindrical body that surrounds the periphery of the exciting coil 20 at a predetermined angle in the circumferential direction and has an arc shape when viewed from the rotation center axis direction of the shaft 10. The center axis CL3 of the arc of curvature coincides with the rotation center axis CL1. In addition to the rotation of the shaft 10, the stator shield 30 is fixedly disposed, for example, on the case of the rotation sensor 1 (not shown in detail here) in the same manner as the excitation coil 20.

  A spacer (not shown) having a certain thickness is interposed between the coil 20 and the stator shield 30. By inserting a spacer having such a constant thickness in the excitation coil 20 that is coaxial with the rotation center axis CL1 of the shaft 10, the curvature center axis CL3 of the stator shield 30 and the rotation center axis CL1 of the shaft 10 are matched. It becomes possible.

  That is, the stator shield 30 has an arc shape when viewed from the rotation center axis CL1 of the shaft 10, and the curvature center axis CL3 of the stator shield 30 always matches the rotation center axis CL1 of the shaft 10 during rotation of the shaft 10. It has become.

  The rotor shield 40 is made of, for example, a semicircular plate made of iron, and is abutted against the semicircular notch step portions 11 formed at both ends of the shaft 10 to be fastened with bolts or the like not shown here. It is fixed by tools or welding.

  Next, the operation of the rotation sensor 1 having such a configuration will be described.

  First, a method for assembling the rotation sensor 1 will be described. First, the shaft 10 provided with the rotor shield 40 at one end is prepared. And this shaft 10 is inserted in the exciting coil 20 which wound many copper wires in the cylindrical shape to the coil holder. At this time, a coil holder as a support member is interposed between the shaft 10 and the excitation coil 20 so that the coil holder functions as a bearing so that the shaft 10 is rotatably supported by the excitation coil 20. To do. Then, the rotor shield 40 is fixed to the other end of the shaft 10 protruding from the other opening of the exciting coil 20 by a fastener such as a screw or welding. At the same time, the stator shield 30 having a halved cylindrical shape is spaced from the outer peripheral surface of the exciting coil 20 by a predetermined distance, and an appropriate spacer (not shown) is interposed between them. Assemble. Then, the exciting coil 20 and the stator shield 30 are fixed to a case (not shown) of the rotation sensor 1.

  As described above, the rotation sensor 1 according to the present embodiment is assembled by a simple assembly process, and the rotation center axis CL1 of the shaft 10, the center axis CL2 of the exciting coil 20, and the curvature center axis CL3 of the stator shield 30 are matched. be able to. Therefore, it is possible to match these axes without being affected by ease of assembly and part tolerance.

  FIG. 3 shows output characteristics of the rotation sensor 1 assembled by such an assembling process. In this figure, the position of the rotor shield 40 of the rotation sensor 1 in FIGS. 1 and 2 corresponds to the portion having the largest inductance at an angle 180 in FIG. Then, when the shaft 10 is rotated, the rotor shield 40 is rotated in one circumferential direction or the other direction, whereby the rotor shield 40 is gradually reduced in the crossing area of the magnetic flux from the exciting coil 20 to the stator shield 30. The detection output characteristic of the rotation sensor 1 can be improved by linearly changing the inductance of the exciting coil 20 shown in FIG.

  As described above, the rotation sensor 1 according to the present embodiment has the magnetic shaft 10 at the center of the cylindrical excitation coil 20, and the stator shield 30 having a half-divided cylindrical body surrounds the excitation coil 20. The semi-disc shaped rotor shield 40 is fixed to the shaft 10 and arranged on both sides of the exciting coil 20. As the shaft 10 rotates, the rotor shield 40 rotates. As the area where the rotor shield 40 shields the magnetic flux from the exciting coil 20 to the stator shield 30 changes linearly, the inductance of the exciting coil 20 also becomes linear. To change.

  That is, by arranging the shaft 10, the excitation coil 20, the stator shield 30, and the rotor shield 40 on the same central axis, the semicircular rotor shield 40 rotates on both sides of the excitation coil 20. The inductance can be changed linearly.

  Further, by arranging the rotor shield 40 on the outside of the exciting coil 20 and arranging the parts on the same central axis, the backlash between the parts can be reduced, and the rotor shield 40 can prevent the stator shield 30 from the exciting coil 20. As the area shielded by the magnetic flux changes linearly, the inductance of the exciting coil 20 can also be changed linearly.

  On the other hand, the modification concerning the rotation sensor 1 of this embodiment as shown in FIG. 4 is also considered. In the rotation sensor 2 according to this modification, the rotor shield 50 does not have a semicircular plate shape as in the above-described embodiment, but has an irregular semicircular shape when viewed from the rotation center axis direction of the shaft 10. . The other components, that is, the shape and material of the shaft 10, the exciting coil 20, and the stator shield 30 are the same as those in the above-described embodiment, and accordingly, the corresponding reference numerals are given here and detailed description thereof is omitted. .

  Since this rotation sensor 2 also has such a configuration, it can be easily assembled in the same manner as the rotation sensor 1 described above, and without being affected by ease of assembly and component tolerances, the rotation center axis CL1 of the shaft 10, The curvature rotation center CL3 of the stator shield and the rotation center CL5 of the rotor shield 50 can be matched.

  FIG. 5 is a diagram showing the output characteristics of the rotation sensor 2 having such an unusual rotor shield 50. The position of the rotor shield 50 of the rotation sensor shown in FIG. 4 corresponds to the 0 ° position in FIG. As the shaft 10 rotates in one circumferential direction, the rotor shield 50 integrated with the shaft 10 changes the area crossing the magnetic flux from the excitation coil 20 to the stator shield 30 in the same manner as in the above-described embodiment. The amount of change in the inductance of the coil 20 also changes as shown in FIG.

  As is apparent from FIG. 5, the amount of change in inductance of the exciting coil 20 has an increase characteristic and a decrease characteristic different from the amount of change in inductance shown in FIG. 3 when the shaft 10 rotates 360 °. By changing the shape of the rotor shield 50 in this way, the characteristic of the inductance change amount of the exciting coil 20 accompanying the rotation of the shaft 10 can be made a desired characteristic, for example, within a certain rotation angle range of 360 °. When the rotation angle is required to be measured accurately in the above-mentioned range, and the rotation angle measurement is not so accurate in the other rotation angle ranges, the rotor shield 50 is obtained so as to obtain an output characteristic having an inductance change amount corresponding thereto. The shape can be changed as appropriate.

  As described above, the rotation sensor according to the present embodiment and the modification thereof has the above-described configuration, so that the rotation center axis of the shaft and the center axis of the excitation coil always coincide with each other during the rotation of the shaft. During the rotation of the shaft, the rotation center axis of the shaft, the center axis of the rotor shield, and the curvature center axis of the stator shield always coincide with each other.

  As a result, even if the rotation sensor is easy to assemble, there is a variation in the tolerances of each part, priority is given to assemblyability, and even if some tolerance is allowed, the sensing unit rotates with the shaft. As a result, there is no variation in the characteristics of the detection output without causing a fluctuation in the radial direction of the coil, and a rotation sensor having always stable output characteristics can be obtained.

  In addition, the material of a shaft, a stator shield, and a rotor shield is not limited to the material of embodiment mentioned above. Therefore, for example, materials such as iron, copper, brass, aluminum, and silver are conceivable as materials for the shaft, the stator shield, and the rotor shield.

  Next, a specific example according to the embodiment of the rotation sensor according to the present invention will be described with reference to FIGS. In addition, about the structure equivalent to the rotation sensor 1 of embodiment mentioned above, a corresponding code | symbol is attached | subjected and detailed description is abbreviate | omitted.

  The rotation sensor 1 according to the above-described embodiment and the rotation sensor 3 have the same basic configuration, and the rotation sensor 3 is shown in a configuration in which the portion of the excitation coil 121 in FIG. 6 and FIG. Has been. That is, the shape and material of the shaft 110, the stator shield 130, and the rotor shield 140 of the rotation sensor 3 are the same as those of the rotation sensor 1 of the above-described embodiment.

  The coil holder 122 is made of, for example, a nonmagnetic resin material such as PBT (polybutylene terephthalate), and has flange portions 122a and 122b whose diameters are enlarged at both ends, and at the one end, the winding start and end of the exciting coil 121 are provided. It has a cylindrical shape with a protruding portion 122c that forms a terminal holding portion. In addition, a large number of copper wires are wound around the outer periphery of the coil holder 122 in a cylindrical shape to form an exciting coil 121. Further, the inner peripheral surface of the coil holder 122 can slide with the shaft 100 as a bearing member.

  The exciting coil 121 is held by the stator shield 130 via a part of the flanges 122a and 122b of the coil holder 122. That is, in this case, part of the flanges 122a and 122b of the coil holder 122 serves as a spacer. Thus, the spacer may have other functions.

  Since the rotation sensor 3 according to this specific example has such a configuration, the assembly procedure of the rotation sensor 3 is the same as the assembly procedure of the rotation sensor 1 according to the above-described embodiment. As for the third action, the same action as that of the rotation sensor 1 described above can be exhibited.

  The rotation sensor according to the present invention is suitable for detecting the vehicle height and the inclination of the vehicle body. However, the rotation sensor according to the present invention can be applied to any sensor as long as it obtains the relative rotation angle and rotation torque between shafts that rotate with each other, such as a robot arm.

It is sectional drawing which cut | disconnected along the longitudinal direction and showed roughly the rotation sensor concerning one Embodiment of this invention. It is the end elevation seen from the rotation center axis direction of the shaft of the rotation sensor concerning one embodiment of the present invention shown in FIG. It is a detection output characteristic figure of the rotation sensor concerning one embodiment of the present invention shown in FIG. It is the end elevation which looked at the modification of the rotation sensor shown in FIG. 1 from the rotation center axis line direction of the shaft. It is a detection output characteristic figure of a rotation sensor concerning a modification of the present invention shown in FIG. It is sectional drawing along the longitudinal direction of the shaft of the specific example of the rotation sensor concerning this invention. It is the end elevation seen from the rotation center axis direction of the shaft of the rotation sensor shown in FIG.

Explanation of symbols

1, 2 and 3 Rotation sensor 10 Shaft 11 Notch step 20 Excitation coil 30 Stator shield 40 Rotor shield 41 Diameter end face 50 Rotor shield 100 Shaft 121 Excitation coil 122 Coil holder 130 Stator shield 140 Rotor shield 122a, 122b Flange CL1 Center axis of rotation CL2 Center axis CL3 Center axis of curvature of stator shield CL5 Center axis of rotor shield 50

Claims (3)

A rotating body to be measured that rotates about a specific rotation center axis;
A rotation axis that is fixedly arranged independently of the rotation body to be measured so as to surround the rotation body to be measured, has a central axis that approximately matches the rotation center axis of the rotation body to be measured, and directly or a bearing member. An excitation coil rotatably held by the rotating body to be measured via,
A stator shield fixedly arranged independently of the rotation of the rotating body for measurement so as to surround the excitation coil by a predetermined angle in the circumferential direction of the excitation coil;
A rotor shield that is attached to the rotating body for measurement and rotates together with the rotation of the rotating body for measurement;
A rotation sensor characterized in that the area of the rotor shield that crosses the magnetic flux from the exciting coil to the stator shield changes according to the rotation of the rotating body to be measured. The rotating body for measurement consists of a shaft,
The excitation coil has a cylindrical body,
The stator shield is a partial cylindrical body having an arc shape when viewed from the rotational center axis direction of the rotating body to be measured, and surrounds the excitation coil around a predetermined angle in the circumferential direction and coincides with the rotational center axis line. It has a central axis of curvature of the arc,
2. The rotation sensor according to claim 1, wherein the rotor shield is formed of a partial disk body provided at at least one end of the shaft and formed at a predetermined angle in a circumferential direction. The rotation sensor according to claim 1, wherein the stator shield is held by the exciting coil via a spacer.

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