JP3869321B2 - Rotation sensor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a rotation sensor.
[0002]
[Prior art]
As a rotation sensor including a rotating body (rotor) having an insulating magnetic material layer and a conductor and a fixed core having an exciting coil, for example, an automobile in which two rotating shafts that rotate relative to each other via a torsion joint are connected 2. Description of the Related Art A rotation sensor that detects rotational torque in a handle shaft is known.
[0003]
In such a rotation sensor, for example, a first rotor in which magnetic bodies and nonmagnetic metal bodies are alternately arranged at equal intervals in the circumferential direction in conjunction with a wheel-side rotation shaft of the handle shaft, and the handle shaft. The magnetic field changes depending on the relative rotational position of the second rotor formed by cutting the non-magnetic metal body at equal intervals in the circumferential direction in conjunction with the rotation axis on the handle side. Therefore, the effective inductance generated in the exciting coil of the fixed core is changed by the eddy current generated according to the area of the conductor crossing the magnetic field, and the angle of the relative rotational deviation between the two rotating shafts is detected as the rotational torque. There is something.
[0004]
[Problems to be solved by the invention]
By the way, in the rotation sensor, the forming accuracy of the rotor and the fixed core, the non-uniform distribution of the magnetic permeability in the circumferential direction of the rotor and the fixed core, the assembly accuracy of the fixed core, or the rotor and the fixed core when assembled to the handle shaft The difference in concentricity increases the accuracy change called Rotational Accuracy, and the desired performance cannot be obtained.
[0005]
Here, the change in accuracy means a change in the effective inductance of the exciting coil when the first and second rotors make one rotation without relative rotation.
Moreover, it is not feasible from the viewpoint of the manufacturing cost of the rotation sensor to optimally control each factor causing the change in accuracy to form, assemble, or assemble the rotor and the fixed core.
[0006]
In addition, the factors causing the change in accuracy are not determined uniquely because they act in a complex manner with each other. Therefore, it is very difficult to predict the performance of the rotation sensor as a product.
The present invention has been made in view of the above points, and an object thereof is to provide a rotation sensor capable of controlling a change in accuracy with respect to a product manufactured within a predetermined standard.
[0007]
[Means for Solving the Problems]
Since in the present invention to achieve the above object, a first rotor which is an insulating magnetic material layer and the conductive layer, attached to the predetermined axial position of the first shaft to rotate,
Is fixed to the fixing member, and a fixed core having an exciting coil,
Adjacent to the first rotor and attached to a second shaft that rotates relative to the first shaft, has shielding teeth, and is disposed between the first rotor and the fixed core. A second rotor ;
Is connected to the front Symbol exciting coil, an oscillating means for oscillating an oscillation signal of a specific frequency,
And adjusting means for adjusting the effective inductance of the previous Symbol excitation coil,
In the rotation sensor with
The fixed core has two excitation coils arranged symmetrically with respect to a plane orthogonal to the rotation axes of the first and second rotors, and a case that houses both the excitation coils, and the adjustment means includes at least is formed in a holding member for holding the one of the exciting coils, extending outward from the case, it is characterized by a flange portion for rotating the exciting coil to the rotation axis.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a torque sensor for detecting torque will be described in detail with reference to FIGS. 1 to 10 as an embodiment of the rotation sensor of the present invention.
First, as shown in FIGS. 1 and 2, the torque sensor 1 according to the first embodiment includes a first rotor 2, a fixed core 3, and a second rotor 5, and a first shaft SF <b> 1 and a second shaft that rotate relative to each other. Torque associated with relative rotation is detected based on the relative rotation angle of the shaft SF2 (see FIG. 2). The torque sensor 1 is used, for example, when the rotational torque of the steering shaft of an automobile is detected by transmitting the rotational torque from the main drive shaft to the driven shaft by a conversion joint (torsion bar) JT. The relative rotation angle varies within a range of ± 8 °.
[0010]
Here, in FIG. 1, Art is the rotation axis of the first rotor 2 and the second rotor 5. Both the x axis and the y axis are orthogonal to the rotation axis Art, and the x axis and the y axis are orthogonal to each other.
The first rotor 2 is formed in a cylindrical shape, and is attached to a predetermined position in the axial direction of the rotating first shaft SF1, as shown in FIGS. As shown in the figure, the first rotor 2 has a flange 2b that extends radially outward at the top of the cylindrical shaft 2a and is integrally formed of synthetic resin. An insulating magnetic member 2c is attached to the outer periphery of the cylindrical shaft 2a. Yes. The first rotor 2 has a plurality of copper foils 2d attached to the surface of the insulating magnetic member 2c along the circumferential direction at predetermined intervals, for example, central angle intervals of 60 °.
[0011]
However, the copper foil 2d may be provided not inside the surface of the insulating magnetic member 2c but inside. In addition to the copper foil 2d, the conductor layer may be made of a material such as aluminum, silver, iron, etc., as long as it is a conductor. Since the torque sensor 1 of the present embodiment has the plurality of copper foils 2d arranged at intervals of the central angle of 60 ° as described above, the maximum measurable angle range is about 30 °.
[0012]
As shown in FIGS. 1 and 2, the fixed core 3 is fixed to a fixing member (not shown) located in the vicinity of the handle shaft with a predetermined gap in the radial direction from the first rotor 2. The fixed core 3 has a core body 3a made of an insulating magnetic material, an exciting coil 3b that forms a magnetic circuit in cooperation with the insulating magnetic member 2c of the first rotor 2, and a coil bobbin 3c that holds the magnetic coil 3b. Is housed in an aluminum case 4. The exciting coil 3b is connected to a signal processing circuit (not shown) by an electric wire 3d (see FIG. 1) extended to the outside, and an alternating current is passed from the signal processing circuit.
[0013]
As shown in FIGS. 1 and 2, the case 4 has an upper cover 4b and a lower cover 4c attached to the top and bottom of the main body 4a. The main body 4a has an axis parallel to the x axis and an axis parallel to the y axis. Four adjustment screws 4d are provided at intervals of 90 degrees. Each adjustment screw 4d is an adjustment means for adjusting the effective inductance of the exciting coil 3b by changing the poloidal magnetic circuit by changing the radial position of the exciting coil 3b, and is fixed via the pressing member 4e. The core 4 and thus the exciting coil 3b are pressed in the radial direction and moved slightly.
[0014]
As shown in FIGS. 1 and 2, the second rotor 5 has a plurality of metal teeth 5 b that serve as shielding teeth arranged in a ring shape on a ring-shaped main body 5 a, and each metal tooth 5 b is a copper foil. It has an interval corresponding to 2d. The second rotor 5 is made of, for example, copper, copper alloy, aluminum, aluminum alloy, iron, or iron alloy. As shown in FIG. 1, the plurality of metal teeth 5b are equally arranged in a ring shape like the copper foil 2d. It is provided corresponding to the copper foil 2d. The second rotor 5 can also be configured as follows. That is, a cylindrical surface made of an insulating material that does not have magnetism or a certain thickness of a shielding layer (for example, 0.2 mm copper foil or aluminum, silver, iron, etc.) made of copper The same number as that of the foil 2d is made to correspond to the copper foil 2d and arranged in a ring shape evenly. The second rotor 5 is attached to a second shaft SF2 (see FIG. 2) adjacent to the first rotor 2 and rotating relative to the first shaft SF1, and the plurality of metal teeth 5b are as shown in FIG. The first rotor 2 and the fixed core 3 are disposed.
[0015]
The torque sensor 1 configured as described above is assembled by attaching the first rotor 2 to the first shaft SF1, the second rotor 5 to the second shaft SF2, and fixing the fixed core 3 to the fixing member. It is done.
And in the assembled torque sensor 1, the magnetic flux by the alternating current which flows through the exciting coil 3b flows along the said magnetic circuit formed between the insulating magnetic member 2c and the exciting coil 3b. Thereby, since the alternating magnetic field crosses the plurality of copper foils 2d of the first rotor 2, an eddy current is induced on the surface of the copper foil 2d. As a result, the magnetic resistance increases in the portion where the copper foil 2d is present.
[0016]
Accordingly, in the torque sensor 1, the copper foil 2 d exists in the gap G formed between the first rotor 2 and the fixed core 3, and the region Asp where the magnetic resistance is large and the copper foil 2 d do not exist. The regions Ade having a small magnetic resistance are alternately formed in the circumferential direction. As a result, in the torque sensor 1, a non-uniform magnetic field having a central angle of 60 ° is formed in the circumferential direction in the gap G between the first rotor 2 and the fixed core 3. Here, in FIG. 3, the cylindrical shaft 2 a of the first rotor 2 is omitted from illustration.
[0017]
Accordingly, when the first rotor 2 rotates relative to the second rotor 5 together with the first shaft SF1, the non-uniform magnetic field also rotates along the circumferential direction together with the first rotor 2. For this reason, in the gap G, the metal teeth 5b formed in the circumferential direction at intervals of the central angle of 60 ° cross the uneven magnetic field, and at this time, the metal teeth are caused by relative rotation between the first rotor 2 and the second rotor 5. The ratio of the area 5b located in the region Asp where the magnetic resistance is large and the ratio of the area located in the region Ade where the magnetic resistance is small changes, and the total amount of magnetic flux crossing the space between the first rotor 2 and the fixed core 3 is Change.
[0018]
As a result, in the torque sensor 1, the magnetic flux self-induced to the coil is different, and the inductance of the exciting coil 3 b varies depending on the relative rotation angle between the first rotor 2 and the second rotor 5. Therefore, if the torque sensor 1 measures the inductance using a known method in a signal processing circuit connected to the excitation coil 3b, the relative rotation angle between the first rotor 2 and the second rotor 5, and thus the torque can be easily obtained. Can be detected.
[0019]
The measurement of the accuracy change of the torque sensor 1 is carried out by rotating both of them relative to the fixed core 3 while making the relative rotation angle between the first rotor 2 and the second rotor 5 0 °. When the effective inductance of 3b is measured, a synthetic wave having a period of 360 ° / n corresponding to the number n of the shielding teeth 5b is obtained. Therefore, since the torque sensor 1 has the six shielding teeth 5b, a composite wave having a period of 360 ° / 6 = 60 ° can be obtained.
[0020]
Here, when the concentricity between the exciting coil 3b and the first rotor 2 or the second rotor 5 is extremely bad, a waveform with a period of 360 ° becomes remarkable, and the exciting coil 3b, the core body 3a, and the insulating magnetic member 2c When the shape is elliptic rather than circular, a waveform with a period of 180 ° becomes prominent.
For this reason, the torque sensor 1 measures the change in accuracy after manufacturing, and if there is a noticeable waveform, it is necessary to control the change in accuracy by making the waveform as small as possible to reduce the change range of the accuracy change. There is.
[0021]
An example in which the accuracy change of the torque sensor 1 is controlled by changing the position of the fixed core 3 will be described. First, the accuracy change of the manufactured torque sensor 1 is measured by rotating the first and second rotors 2 and 5 relatively once with respect to the fixed core 3 without rotating relative to the fixed core 3 to effectively measure the excitation coil 3b. This is done by measuring the change in inductance. Based on this result, when there is a remarkable waveform, the position of the fixed core 3 is shifted and finely adjusted by the adjusting screw 4d. The accuracy change of the torque sensor 1 is measured again to confirm that the change width has become smaller. If this cannot be confirmed, a series of operations for finely adjusting the position of the fixed core 3 with the adjusting screw 4d and measuring the accuracy change are repeated until this can be confirmed.
[0022]
A specific example will be described. The fixed core 3 is fixed to an appropriate fixing member, and the rotors 2 and 5 are rotated once without causing rotational deviation while an alternating current having a frequency of 100 kHz and a voltage amplitude of 2 V is supplied from the signal processing circuit to the exciting coil 3b. The change in accuracy of the torque sensor 1 before shipment was measured. At this time, the change in the effective inductance of the exciting coil 3b was measured with an LCR (Agilent Tech 4284A) meter. The result is shown by a dotted line in FIG.
[0023]
Based on the measurement result, the adjustment screw 4d is appropriately operated to move the position of the exciting coil 3b by 0.2 mm in the positive direction of the x-axis, and then the measurement result of the accuracy change of the torque sensor 1 measured in the same manner is obtained. This is indicated by a solid line in FIG.
Here, the torque sensor 1 can also control the accuracy change by changing the magnetic circuit in the poloidal direction by changing the shape of the upper cover 4b or the lower cover 4c of the case 4.
[0024]
For example, as shown in FIGS. 4 and 5, the torque sensor 1 has an extending portion that protrudes radially inward in a sinusoidal manner at a cycle of 60 ° along the circumferential direction on the inner periphery of the upper cover 4 b of the case 4. 4f is formed. Then, an AC current having a frequency of 100 kHz and a voltage amplitude of 2 V is passed from the signal processing circuit to the exciting coil 3b, and the first and second rotors (not shown) are both relative to the fixed core 3 without causing rotational deviation. 1 revolution, and after measuring the change in the effective inductance of the exciting coil 3b and measuring the accuracy change (see the dotted line in FIG. 6), the upper cover 4b is rotated based on this result, and the torque before shipping. The accuracy change of the sensor 1 is controlled. This operation is performed until the change width of the accuracy change becomes small. Based on the above results, the accuracy change was measured after the upper cover 4b was rotated by 2 °. As shown by the solid line in FIG. 6, the amplitude of the waveform with a cycle of 60 ° was reduced by about 60%.
[0025]
Next, a double-coil torque sensor will be described with reference to FIGS. 7 to 9 as a torque sensor according to the second embodiment.
As shown in FIGS. 7 and 8, the torque sensor 10 includes a first rotor 11, a fixed core 12, a second rotor 13, and a relative rotation angle measurement device 14. Here, the main driving shaft rotates relative to the driven shaft within a range of ± 8 °.
[0026]
The first rotor 11 is made of a soft magnetic material powder made of Ni-Zn or Mn-Zn ferrite in a thermoplastic synthetic resin having electrical insulation properties such as nylon, polypropylene (PP), polyphenylene sulfide (PPS), ABS resin, etc. Is formed into a cylindrical shape by an insulating magnetic material mixed with a soft magnetic material content of 10 to 70% by volume, and is attached to a predetermined position in the axial direction of the rotating main driving shaft. The first rotor 11 is arranged on the innermost side, and as shown in FIG. 7, the first rotor 11 is arranged on the outer circumference in two stages in the direction of the rotation axis Art, and at a predetermined interval in the circumferential direction, for example, alternately shifted in the vertical direction. A plurality of copper foils 11a are provided at intervals of 30 ° of the central angle.
[0027]
Here, the copper foil 11a may be disposed on the outer periphery of at least one of the upper and lower parts divided in the upper and lower stages in the direction of the rotation axis Art and may be provided at a predetermined interval in the circumferential direction. Therefore, the copper foil 11a may be provided at a predetermined interval only on the upper side or the lower side, or provided at a predetermined interval on the upper side or the lower side, and may be provided on the lower side or the upper side over the entire circumference. Moreover, if it is a conductor layer, materials, such as aluminum and silver, can be used, for example, These conductor layers containing the copper foil 11a may be embedded in the inside of an insulating magnetic material.
[0028]
The fixed core 12 is disposed outside the first rotor 11 with a slight gap of about several millimeters in the radial direction, and is fixed to a fixing member (not shown) positioned in the vicinity of the steering shaft. As shown in FIG. 8, the fixed core 12 houses two core bodies 12a made of the same insulating magnetic material as the first rotor 11, a coil bobbin 12c housed in each core body 12a, and both core bodies 12a. And a shielding case (hereinafter simply referred to as “case”) 12d made of a conductive member. Each exciting coil 12b is connected to a signal processing circuit (not shown) by an electric wire 12e (see FIG. 7) extending from the case 12d to the outside, and an alternating current is passed from the signal processing circuit. The case 12d is made of a carbon-mixed plastic having a volume resistivity of about 10 ⁻¹ to 10 ⁻² Ω · cm, in which carbon is mixed in a synthetic resin such as aluminum, copper, or PPS (polyphenylene sulfide) that has an AC magnetic field shielding property. The conductive member is formed in a ring shape having two recesses 12f for accommodating each core body 12a.
[0029]
Here, as shown in FIGS. 7 and 8, the case 12 d has an opening 12 g formed in a range of a central angle of 90 ° above and below the side wall. Each coil bobbin 12c is wound with an exciting coil 12b, and a flange portion 12h extending from the core body 12a protrudes from the opening 12g to the outside of the case 12d.
Further, the fixed core 12 has a surface facing the case 12d as shown in FIG. 2 with respect to a surface orthogonal to the rotation axis Art between the upper core body 12a and the excitation coil 12b and the lower core body 12a and the excitation coil 12b. The upper core body 12a and the exciting coil 12b and the lower core body 12a and the exciting coil 12b are arranged symmetrically with respect to the plane. Further, the two exciting coils 12b each reverse the direction of the magnetic circuit formed between the first rotor 11 by setting the winding direction to be opposite or by reversing the direction in which an alternating current flows. .
[0030]
As shown in FIG. 7, the second rotor 13 has a plurality of blades 13b that are parallel to the rotation axis Artt on the outer periphery of the flange 13a by using a synthetic resin having electrical insulation and excellent moldability. Is formed. The plurality of blades 13b are disposed between the first rotor 11 and the fixed core 12 when viewed in the radial direction. Each wing plate 13b is formed at intervals corresponding to each copper foil 11a, and a copper foil 13c is provided on the outer surface.
[0031]
At this time, the second rotor 13 has a conductor layer (for example, a 0.2 mm copper foil, aluminum, or the like) on the inner surface of each slat 13b or the inner surface or the inside of a cylinder made of an insulating material. A material such as silver) may be evenly arranged corresponding to the copper foil 11a, and this also applies to a torque sensor described later. The second rotor 13 is disposed between the first rotor 11 and the fixed core 12 and is attached to the driven shaft that rotates relative to the main driving shaft.
[0032]
The relative rotation angle measuring device 14 is attached to the lower part of the fixed core 12 in the form of a wiring board. As shown in FIG. 9, an oscillation circuit 14a that oscillates an oscillation signal and a pulse of a specific frequency by dividing the oscillation signal. A frequency dividing circuit 14b for outputting a signal, a phase shift unit 14c for shifting the phase of the pulse signal generated in each of the two excitation coils 12b, and first and second shifts for detecting each detected phase shift amount Amount detectors 14d and 14e, first and second converters 14f and 14g for converting the detected shift amounts into corresponding voltage values, and first and second shifts for adjusting the shift levels of the voltage values. The level adjustment units 14h and 14i obtain the difference between the voltage corresponding to the shift amount from the first converter 14f and the adjusted voltage from the second shift level adjustment unit 14i. One differential amplifier 14j, a second differential amplifier 14k for obtaining a difference between the adjusted voltage from the first shift level adjusting unit 14h and the voltage corresponding to the shift amount from the second converter 14g, And a relative rotation angle measuring unit 14m that measures the relative rotation angle from the obtained voltage of each difference.
[0033]
The oscillation circuit 14a outputs a pulse signal having a specific frequency to the phase shift unit 14c via the frequency dividing circuit 14b.
The phase shift unit 14c is configured by exciting coils 12b and 12b connected in series, and a capacitor C1, resistor R1, and capacitor C2 connected in series are connected in parallel with the exciting coils 12b and 12b. The exciting coils 12b and 12b are wound around a fixed core to allow an alternating current to flow, and form a magnetic circuit in cooperation with the first rotor. The phase shift unit 14c shifts the phase of the pulse signal input from the frequency dividing circuit 14b connected between the exciting coils 12b and 12b according to the magnitude of the eddy current generated in the second rotor.
[0034]
The first and second shift amount detectors 14d and 14e are respectively connected to one end of each exciting coil 12b, and the first shift amount detector 14d detects the phase shift amount of the pulse signal between the points A and B. Then, the second shift amount detector 14d detects the phase shift amount by detecting the phase shift amount of the pulse signal at the points A and C.
The first and second converters 14f and 14g convert the detected shift amounts into corresponding voltage values S1 and S2, and the shift level adjusting units 14h and 14i are voltages of pulse signals input from the converters 14f and 14g. The shift levels of the values S1 and S2 are adjusted and output to the first and second differential amplifiers 14j and 14k. The first differential amplifier 14j obtains a difference between the voltage value S1 of the pulse signal from the converter 14f and the voltage value S2 of the pulse signal from the shift level adjustment unit 14i, and a signal having an output level twice as high as the original signal. T1 (voltage value) is output to the relative rotation angle measurement unit 14m. Further, the differential amplifier 14k obtains a difference between the voltage value S2 of the pulse signal input from the converter 14g and the voltage value S1 of the pulse signal from the shift level adjustment unit 14h, and a signal having an output level that is twice that of the original signal. T2 (voltage value) is output to the relative rotation angle measurement unit 14m.
[0035]
As shown in FIG. 5, the relative rotation angle measurement unit 14m can measure the relative rotation angles of the two rotors with high accuracy in the range of −8 ° to + 8 ° based on the voltage values of the signals T1 and T2.
The torque sensor 10 configured as described above has a first rotor 11 attached to the main driving shaft, a second rotor 13 attached to the driven shaft, and a fixed core 12 fixed to the fixing member, to the steering device. The rotational torque of the handle shaft is detected as the steering handle is assembled.
[0036]
In the torque sensor 10, similarly to the torque sensor 1, when controlling the change (precision change) of the effective inductance of the exciting coil 3b, the flange 12h protruding from the case 12d is rotated in the circumferential direction along the opening 12g. Manipulate.
Here, in the torque sensor 10, each of the upper and lower exciting coils 12 b when the first and second rotors 11 and 13 are rotated once relative to the fixed core 12 without causing rotational deviation. It is necessary to make the change in effective inductance (change in accuracy) as identical as possible. Therefore, based on the measurement result of each effective inductance, the position of each of the upper and lower fixed cores 12 is shifted as necessary to control the change in accuracy of both.
[0037]
Specifically, in the same manner as the torque sensor 1, the change in effective inductance of each exciting coil 12b in the torque sensor 10 before shipment was measured with an LCR meter. The result is shown in FIG. 10A by the solid line for the upper exciting coil 12b and by the dotted line for the lower exciting coil 12b.
Then, after the upper excitation coil 12b was rotated 5 ° by the flange 12h, the change in effective inductance of each excitation coil 12b was measured with an LCR meter in the same manner. The result is shown in FIG. 10B by the solid line for the upper exciting coil 12b and by the dotted line for the lower exciting coil 12b.
[0038]
10A and 10B, the change in the phase of the waveform having a period of 60 ° was read. As a result, the phase of the torque sensor 10 was changed by about 3.8 ° by rotating the excitation coil 12b by 5 °.
[0039]
【The invention's effect】
According to the first aspect of the present invention, it is possible to provide a rotation sensor capable of controlling a change in accuracy with respect to a product manufactured within a predetermined standard.
[Brief description of the drawings]
FIG. 1 shows an embodiment of a rotation sensor according to the present invention, and is an exploded perspective view of a torque sensor according to a first embodiment.
FIG. 2 is a cross-sectional view on the left half side of the state where the torque sensor shown in FIG. 1 is attached to a relatively rotating shaft.
3 is a diagram showing a change in effective inductance of an exciting coil before and after adjustment in the manufactured torque sensor of FIG. 1; FIG.
4 is a plan view of an upper cover showing a modification of the torque sensor in FIG. 1. FIG.
5 is a cross-sectional view of the left half side of the fixed core in the torque sensor provided with the upper cover of FIG. 4;
6 is a diagram showing a change in effective inductance of the exciting coil before and after adjustment in the torque sensor using the fixed core of FIG. 5;
FIG. 7 is an exploded perspective view of a torque sensor according to a second embodiment, showing an embodiment of the rotation sensor of the present invention.
8 is a cross-sectional view of the left half side of a fixed core used in the torque sensor of FIG.
9 is a circuit diagram showing an example of a relative rotation angle measuring device used in the torque sensor of FIG. 7;
10 is a diagram showing a change in effective inductance of the exciting coil before and after adjustment in the torque sensor of FIG. 7;
[Explanation of symbols]
1 Torque sensor (rotation sensor)
2 First rotor 3 Fixed core 4 Case 4
4b Upper cover 4c Lower cover 4d Adjustment screw (adjustment means)
4f Extension part (adjustment means)
5 2nd rotor 10 Torque sensor 11 1st rotor 12 Fixed core 12c Coil bobbin 12h A collar part (adjustment means)
13 Second rotor 14 Relative rotation angle measuring device Art Rotation axis SF1 First shaft SF2 Second shaft

Claims (1)

An insulating magnetic material layer and the conductive layer, a first rotor mounted in the predetermined axial position of the first shaft to rotate,
Is fixed to the fixing member, and a fixed core having an exciting coil,
Adjacent to the first rotor and attached to a second shaft that rotates relative to the first shaft, has shielding teeth, and is disposed between the first rotor and the fixed core. A second rotor ;
Is connected to the front Symbol exciting coil, an oscillating means for oscillating an oscillation signal of a specific frequency,
And adjusting means for adjusting the effective inductance of the previous Symbol excitation coil,
In the rotation sensor with
The fixed core has two excitation coils arranged symmetrically with respect to a plane orthogonal to the rotation axes of the first and second rotors, and a case that houses both the excitation coils, and the adjustment means includes at least A rotation sensor that is formed on a holding member that holds one excitation coil and that extends outward from the case and rotates the excitation coil around the rotation axis .

Images