JP5135277B2 - Rotary position detector - Google Patents

Description

The present invention relates to a rotary position detection apparatus including a coil that is AC-excited and a magnetic body or a conductor that is displaced relative to the coil.

  An inductive rotational position detection device that produces two-phase output (sine phase and cosine phase output) with one-phase excitation input is known as a “resolver”, and three-phase output (120 degrees with one-phase excitation input) What produces the three shifted phases) is known as “synchro”. The oldest conventional resolver has a secondary winding (sine pole and cosine pole) orthogonal to each other at a mechanical angle of 90 degrees on the stator side, and a primary winding on the rotor side. Is. This type of resolver is disadvantageous because it requires a brush to make electrical contact with the rotor primary winding. On the other hand, the existence of a brushless resolver that does not require a brush is also known. The brushless resolver is provided with a rotary transformer in place of the brush on the rotor side. However, since such a brushless resolver has a configuration in which a rotary transformer is provided on the rotor side, it is difficult to reduce the size of the device, and there is a limit to downsizing, and the configuration of the device is equivalent to that of the rotary transformer. Since the number of parts increases, the manufacturing cost will increase.

  On the other hand, primary windings and secondary windings are arranged on a plurality of convex poles on the stator side, and the rotor is made of a magnetic material having a predetermined shape (eccentric circular shape, elliptical shape, or shape having protrusions). Based on the fact that the gap between the convex pole and the rotor magnetic body changes according to the rotational position, it generates a magnetoresistive change according to the rotational position and obtains an output signal according to this change. 'Variable magnetoresistive rotational position detection device has long been known as the trade name "Micro Thin". Also, rotational position detectors based on the same variable magnetoresistive principle are disclosed in, for example, Japanese Patent Laid-Open Nos. 55-46862, 55-70406, 59-28603, and the like. In this case, the position detection method based on the output signal includes a phase method (a method in which the detected position data corresponds to the electrical phase angle of the output signal) and a voltage method (the detected position data is the voltage level of the output signal). Both of these methods are known. For example, when the phase method is adopted, the primary windings arranged at different mechanical angles, such as two-phase excitation input or three-phase excitation input, are excited with a plurality of phases shifted in phase, and electric is generated according to the rotational position. A one-phase output signal is generated with the target phase angle shifted. When the voltage method is adopted, the relationship between the primary winding and the secondary winding is opposite to that of the phase method, and a multi-phase output is generated by one-phase excitation input as in the “resolver”.

  A rotational position detection device that generates a plurality of phase outputs with one-phase excitation input, such as a “resolver”, is typically configured to generate a two-phase output of a sine phase output and a cosine phase output. For this reason, the conventional contactless type variable magnetoresistive resolver type rotational position detection device has at least a stator having four poles, each pole being disposed at a mechanical angle of 90 degrees, and the first If the pole is the sine phase, the second pole 90 degrees away from it is the cosine phase, the third pole 90 degrees further away is the minus sign phase, and the fourth pole 90 degrees further away is the minus cosine. It is considered a phase. In that case, the rotor is made of a magnetic material or a conductor in order to cause a change in magnetoresistance according to the rotation of each stator pole, and its shape is a periodic shape such as an eccentric circular shape, an elliptical shape, or a gear shape. Formed. Each stator pole is provided with a primary coil and a secondary coil. When the gap between each stator pole and the rotor changes corresponding to the rotational position of the rotor, the magnetic resistance of the magnetic circuit passing through the stator pole is reduced. Based on this, the degree of magnetic coupling between the primary coil and the secondary coil in the stator pole changes corresponding to the rotational position, and thus an output signal corresponding to the rotational position is induced in the secondary coil. Thus, the peak amplitude characteristic of the output signal of each stator pole shows a periodic function characteristic.

The conventional non-contact type 'variable magnetoresistive type resolver type rotational position detecting device as described above is a primary-secondary induction type in which a primary coil and a secondary coil are provided. Therefore, the number of coils increases. Therefore, there is a limit to downsizing the structure, and there is a limit to reducing the cost. Furthermore, since the conventional rotational position detecting device has a configuration in which a plurality of stator poles are arranged at equal intervals throughout the entire rotation, there is a limit to the applicable place and space due to the structural limitations. In addition, in the conventional rotational position detecting device, even when a two-phase output of sine and cosine is obtained, the stator cannot be a simple two-pole configuration, but has to be a four-pole configuration. There was a limit to downsizing the structure.
Further, Patent Document 1 below discloses a position detection device that obtains a position detection signal based on a change in impedance of a coil excited by an AC signal. However, the position detection device has a configuration in which a plurality of coils are mounted on a stator core formed as a single piece, and if the overall size or shape of the stator is different, a corresponding stator core must be manufactured. Lack of versatility and high cost.

JP 2001-235307 A

The present invention has been made in view of the above points, has a small and simple structure, can be detected with high resolution even if the displacement of the detection target is minute, and is versatile and low-cost, It is an object of the present invention to provide a rotary position detection device.

The rotary position detection device according to the present invention is a coil unit including a plurality of coils excited by an AC signal, and each of the coils is mounted on an independent magnetic core, and each coil and magnetic The set of body cores is configured to be physically separated from the other sets, and each set of the coil and the magnetic core is in a predetermined relative positional relationship with a predetermined less than one rotation of the detection target rotating shaft. some of the rotation angle and the coil portion formed of a fixed place for the fixing member comprising a size within the range, the magnetic response members provided in the rotary shaft so as to relatively displace with respect to the coil portion of the The relative position between the magnetic response member and the coil portion changes in accordance with the rotational position of the rotary shaft , and the magnetism is configured to change the impedance of each coil in accordance with the relative position. Response part With the door, wherein the obtaining the rotation position detection data of the rotation shaft based on the output voltage corresponding to the impedance of each coil.
According to the present invention, has become the individual coils in the coil section are mounted on a respective independently of the magnetic core, a set of the respective coil and the magnetic core is physically separated from the other set configuration since each set of the coil and the magnetic core is a fixing member to the fixing arrangement and formed by arrangement at predetermined relative positional relationship, even if different shapes or sizes of the stator of the rotary position detecting device, the same A combination of type coil and magnetic core can be used. That is, different with respect to the fixed member of the structure, can be arranged mounting a set of coils and magnetic cores of the same type, rich in versatility, by sharing and mass production, the cost of manufacturing rotary position detecting device Can be greatly reduced. In addition, the coil portion is a fixing member having a size within a predetermined partial rotation angle range that is less than one rotation of the rotation shaft of the detection target with a predetermined relative positional relationship between the coil and the magnetic core. Therefore, it is effective when the rotary position detection device according to the present invention is installed later in an existing machine. For example, in the case where an obstacle already exists in a predetermined angle range on the rotation axis to be detected and it is impossible to install a stator coil over a full rotation, it is located at a position in the angle range where no obstacle exists. An excellent effect is obtained in that a coil portion in which a plurality of coils are fixedly arranged on a fixing member having a size within a predetermined partial rotation angle range can be installed.

  In the present invention, each coil and magnetic core group is configured to be physically separated from the other group, so that the coil portion is in an arbitrary range of a predetermined angle within one rotation. It is suitable for being provided in a region, and is suitable for detecting a rotational position in the limited predetermined angle range. In this case, as will be described in detail later, with respect to rotational displacement in a predetermined limited mechanical rotation angle range, a phase detection scale within a predetermined limited range is used instead of a full 360 degree phase detection scale (for example, 60 degree range) position detection data can be obtained. That is, although the detection scale is within a predetermined limited range, two AC output signals similar to the resolver, that is, a sine phase output signal (sin θ sin ωt) and a cosine phase output signal (cos θ sin ωt) can be obtained. Such an arrangement of the biased coil portion is effective when the rotary position detecting device according to the present invention is installed later in an existing machine. For example, in the case where an obstacle already exists in a predetermined angle range on the rotation axis to be detected and it is impossible to install a stator coil over a full rotation, it is located at a position in the angle range where no obstacle exists. This is advantageous because it is possible to install an unevenly arranged coil portion.

  When a non-magnetic good conductor such as copper, that is, a diamagnetic material is used as the magnetic response member, the coil inductance decreases due to eddy current loss, and the voltage across the coil terminal varies depending on the proximity of the magnetic response member. Will decrease. In this case, detection can be performed in the same manner as described above. As the magnetic response member, a hybrid type member in which a magnetic material and a nonmagnetic good conductor (diamagnetic material) are combined may be used.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 shows an embodiment of a rotary type position detection device according to the present invention, in which (A) is a schematic front view showing the structure of the rotary type position detection device, (B) is a schematic side sectional view, and (C) is the rotation. The expansion perspective view of the detection part in a type | mold position detection apparatus.

FIG. 3 is an electric circuit diagram related to a sensor coil in the rotary position detection apparatus shown in FIG. 1.

FIGS. 2A and 2B are explanatory diagrams of detection operation of the embodiment of FIG. 1, in which FIG. 1A shows an ideal curve of impedance change of each detection coil with respect to change of the rotation angle θ, and FIG. The figure which shows the amplitude change characteristic with respect to rotation angle (theta) of the output signal obtained by calculating a voltage.

FIG. 2 shows an example having a housing that performs a magnetic shield function as another embodiment of the sensor head, (A) is a schematic sectional view showing an embodiment in which the entire sensor head is covered with a magnetic housing, and (B) is for a sensor. The cross-sectional schematic diagram which shows the example of a change of the magnetic body core of a coil, (C) is the cross-sectional schematic diagram which shows the example arrange | positioned so that the magnetic body core of the coil for sensors may be oriented in the radial direction of a sensor rotor plate.

The schematic perspective view which shows other Example of a sensor head.

The schematic perspective view which shows the Example of the rotational position detection apparatus provided with the magnetic shielding function in the rotor part.

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1A is a schematic front view showing the structure of a rotary position detecting device according to an embodiment of the present invention, FIG. 1B is a schematic side sectional view thereof, and FIG. 1C is the rotary position detecting device. It is an expansion perspective view of the detection part in. FIG. 2 is an electric circuit diagram related to a sensor coil in the apparatus.
The rotary position detection apparatus shown in this embodiment includes a separation type sensor head that can be disposed at an appropriate position of a rotating body (for example, a rotor) to be detected in order to detect the rotation angle of the motor. This is a rotary position detection device. The rotary position detecting device detects the rotation angle of the main body plate P, which is a rotating body attached to the rotary shaft MJ so as to rotate with the driving of the motor M or the like. A separate type sensor head SH, which is a coil portion including a plurality of detection portions S1 to S4, and a magnetic response member having a predetermined shape that is integrally attached to the main body plate P by a mounting screw T together with a shield ring SR. For example, the sensor rotor plate RP is composed of a magnetic response member made of a magnetic material such as iron). That is, in this rotary type position detecting device, the rotation of the sensor rotor plate RP that rotates around the rotation axis MJ together with the main body plate P is simultaneously detected by the plurality of detection units S1 to S4 of the sensor head SH. The rotation angle of the rotation axis MJ of the motor M can be detected.

  The sensor head SH includes a plurality (four in this embodiment) of detection units S1 to S4 as detection coils for detecting the rotation of the sensor rotor plate RP. Each of the detection units S1 to S4 is directed to the rotation center position of the rotation axis MJ in accordance with the curvature of the main body plate P, and the detection units S1 to S4 are spaced apart at predetermined intervals in the circumferential direction on the sensor head SH. For example, this interval is 15 ° with respect to the rotation center position of the rotation axis MJ. Each detector S1 (S2 to S4) includes two sensor coils L1 (L1 to L4) wound around different magnetic cores C1 (C2 to C4) so as to face each other. The magnetic flux Φ passing through the sensor coils L1 (L2 to L4) is directed in the axial direction of the rotation axis MJ. The magnetic core C1 (C2 to C4) in which the sensor coils L1 (L2 to L4) are arranged is formed by stacking a plurality of silicon steel plates formed in a “C” shape as shown in FIG. It consists of a laminated silicon steel sheet with a shape. When the magnetic core C1 (C2 to C4) is composed of laminated silicon steel plates, the eddy current generated when the magnetic flux generated in each of the sensor coils L1 (L2 to L4) changes can be reduced as much as possible. This is very preferable because current loss can be reduced. Further, by winding the sensor coils L1 to L4 around the magnetic cores C1 to C4 formed in the shape of “C”, a magnetic path (that is, a magnetic flux circuit) for passing the magnetic flux generated in the sensor coils L1 to L4 is formed. Since it is positively generated, the influence of other magnetic flux generated outside can be reduced, which is preferable.

  The sensor rotor plate RP is arranged on the detection units S1 to S4 of the sensor head SH by arranging and arranging each of the sensor coils L1 to L4 and the surface of the sensor rotor plate RP so that a gap is formed. Rotate in a non-contact state. The relative distance between the sensor rotor plate RP and the sensor head SH is determined via a mechanism (not shown) so that the distance of the gap is kept constant. In the case where the sensor rotor plate RP is made of a magnetic material, the sensor rotor plate RP formed in a predetermined shape, for example, a petal shape, according to the rotation position of the main body plate P rotates, thereby magnetizing the sensor coils L1 to L4. The degree of coupling changes. That is, the amount of each magnetic flux penetrating the sensor coils L1 to L4 through the magnetic cores C1 to C4 is changed by changing the facing gap area between the sensor coils L1 to L4 and the surface of the sensor rotor plate RP. As a result, the degree of magnetic coupling for each of the sensor coils L1 to L4 changes. As the degree of magnetic coupling to the sensor coils L1 to L4 increases, the inductance of the sensor coils L1 to L4 increases, so that the electrical impedance of the sensor coils L1 to L4 increases, The voltage generated in the sensor coils L1 to L4, that is, the voltage between terminals increases. On the contrary, as the degree of magnetic coupling to the sensor coils L1 to L4 decreases, the inductance of the sensor coils L1 to L4 decreases, so that the electrical impedance of the sensor coils L1 to L4 is reduced. The voltage generated in the sensor coils L1 to L4, that is, the voltage between terminals decreases. Thus, as the detection target rotates, the voltage between the terminals of the sensor coils L1 to L4 gradually increases while the relative rotation position of the sensor rotor plate RP with respect to the detection units S1 to S4 changes over a predetermined rotation angle range ( (Or gradually decrease).

  The sensor rotor plate RP is a magnetic response member, and its shape is designed to an appropriate shape so as to obtain an ideal sine function curve. The shape of the sensor rotor plate RP is 6 in order to obtain a sine function curve of one cycle per 1/6 rotation of the rotation axis MJ, for example, according to the design 'arrangement conditions of the sensor coils L1 to L4 and the like. In order to obtain a curve of a sine function of one cycle per quarter rotation of the rotation axis MJ, the shape of the sensor rotor plate RP can be a shape of four teeth or four petals. It is not the object of the present invention how to design the shape of the sensor rotor plate RP, and the shape of the rotor employed in this kind of known / unknown variable magnetoresistive rotation detector is the sensor rotor plate. Since it may be adopted as the shape of RP, here, the sensor rotor plate RP having the shape shown in FIG. 1A (that is, the shape of 6 teeth or 6 petals) will be briefly described.

The sensor rotor plate RP shown in the embodiment of FIG. 1A has a plurality of (N) cycles per rotation, such as a multi-tooth or multi-petal (in this embodiment, 6-tooth or 6-petal) that rotates with the rotation axis MJ. Each of the detecting portions S1 to S4 has a structure that is arranged within a narrow range corresponding to 1 / N rotation (that is, 360 degrees / N) of the sensor rotor plate RP. ing. In the embodiment of FIG. 1A, the four detection units S1 to S4 are within the mechanical angle range of 360 degrees / N = 360/6 = 60 degrees and the sensor head SH is spaced at intervals of “60 degrees / 4 = 15 degrees”. Is arranged. The sensor coils L1 to L4 of the detectors S1 to S4 arranged in the sensor head SH are oriented so as to face each other in the axial direction of the rotation axis MJ, and the sensor coils L1 to L4 have six cycles per rotation. It faces the surface of the sensor rotor plate RP having the unevenness variation. The sine function sin θ and the cosine function cos θ obtained thereby have an accuracy of N = 6 times the actual mechanical angle of the rotation axis MJ. For example, if the actual mechanical angle of the rotation axis MJ is ψ, sin θ = sin Nψ and cos θ = cos Nψ. In the present embodiment, since each of the detection parts S1 to S4 of the sensor head SH is arranged in a narrow range corresponding to 1 / N rotation (that is, 360 degrees / N), the mounting space for the sensor head SH Is very suitable for applications in which is limited to a narrow range.
From the above, what is important about the shape of the sensor rotor plate RP is not what the sensor rotor plate RP, that is, the predetermined shape of the magnetic response member is, but in short, the rotation of the sensor rotor plate RP. It is only necessary to design the sensor coils L1 to L4 according to the change in position in the most appropriate shape so that the inductance change, that is, the impedance change, becomes the same as the ideal sine function curve.

In the above-described embodiment, a four-pole configuration in which four detection units S1 to S4 are arranged in the sensor head SH is shown. However, the configuration is not limited to this, and a plurality of detection units S1 to S4 may be configured. That's fine. That is, any configuration may be used as long as an ideal sine function and cosine function can be obtained as the sensor rotor plate RP rotates.
In addition, an example in which two sensor coils L1 to L4 are arranged to face each other of each pole of the sensor head SH so as to sandwich the sensor rotor plate RP is shown. However, the sensor coils L1 to L4 are the same as those of the sensor head SH. One piece may be arranged for each pole on the side surface side. However, if the sensor coils L1 to L4 are arranged opposite to each other for each pole of the sensor head SH so as to sandwich the sensor rotor plate RP as described above, the sensor rotor plate P may be shaken due to the occurrence of calibration. It is preferable because the fluctuation of the magnetic flux accompanying the influence of the above can be canceled.
The main body plate P may be made of a magnetic material such as iron. If it carries out like this, the main body plate P will shield the magnetic flux which generate | occur | produces on the motor M side, and the magnetic flux which generate | occur | produced on the motor M side will not leak to the sensor head SH side. That is, since the sensor coils L1 to L4 of the sensor head SH are not affected by the magnetic flux generated on the motor M side, the rotational position can be accurately detected, which is preferable.
The shield ring SR is preferably made of a diamagnetic material having diamagnetic properties such as gold, copper or silver. In this way, the magnetic flux generated from each of the sensor coils L1 to L4 does not leak to the motor side M, so that an accurate rotation angle can be detected.

FIG. 3A shows an ideal sine function curve of the impedance change of one sensor coil L1 with respect to the change of the rotation angle θ, as A (θ). An ideal sine function curve of the impedance change of the other sensor coil L2 with respect to the change of the rotation angle θ is indicated by B (θ). The impedance change curve B (θ) of the other sensor coil L2 corresponds to a cosine function having a phase shifted by 90 degrees with respect to the sensor coil L1. Thus, if the midpoint of the increase / decrease change of each curve A (θ), B (θ) is P0 and the amplitude of shake is P,
A (θ) = P0 + Psinθ
B (θ) = P0 + Pcosθ
It can be expressed.

Further, the above-described embodiment shows an embodiment in which two differentially changing coil pairs are provided. In this configuration, every other sensor coil is combined to form one set of coil pairs (that is, the sensor coils L1 and L3 and the sensor coils L2 and L4 are combined to form one set of coil pairs). Thus, the impedance of each of the sensor coils L1 to L4 in the one coil pair changes differentially, and therefore the change in the voltage between the terminals of each of the sensor coils L1 to L4 exhibits a differential characteristic. It will be a thing. That is, in the pair of sine phase sensor coils L1 and L3, if the impedance change of the sensor coil L1 exhibits the function characteristic of “P0 + Psinθ” as described above with respect to the rotation angle θ of the rotation axis MJ, The change in impedance of the sensor coil L3 exhibits a function characteristic of “P0−Psinθ” with respect to the rotation angle θ of the rotation axis MJ. Similarly, in the pair of cosine phase sensor coils L2 and L4, assuming that the impedance change of the sensor coil L2 exhibits the function characteristic of “P0 + Pcos θ” as described above with respect to the rotation angle θ of the rotation axis MJ, The change in impedance of the sensor coil L4 shows a function characteristic of “P0−Pcos θ” with respect to the rotation angle θ of the rotation axis MJ. That is,
A ′ (θ) = P0−Psinθ
B ′ (θ) = P 0 −P cos θ
It can be expressed.
It should be noted that even if P is regarded as 1 and omitted, there is no inconvenience in the description, so this will be omitted in the following description.

As shown in FIG. 2, each of the sensor coils L1, L2, L3, and L4 is excited with a constant voltage or a constant current by a predetermined one-phase high-frequency AC signal (indicated by sin ωt) generated from the AC generation source 30. Is done. When the voltage between the terminals of each of the sensor coils L1, L2, L3, and L4 is indicated by Vs, Vc, Vsa, and Vca, respectively, these can be expressed as follows using the rotation angle θ as a variable to be detected.
Vs = A (θ) sinωt = (P0 + sinθ) sinωt
Vsa = A ′ (θ) sin ωt = (P0−sin θ) sin ωt
Vc = B (θ) sinωt = (P0 + cosθ) sinωt
Vca = B ′ (θ) sin ωt = (P0−cos θ) sin ωt
In the arithmetic circuit 31, as described below, an AC output signal having a predetermined periodic amplitude function as an amplitude coefficient is obtained for each coil pair by taking out the difference in voltage between the terminals of each of the sensor coils L1, L2, L3, and L4. Is generated for each coil pair. That is, the output voltages Vs, Vc, Vsa, and Vca of the sensor coils L1, L2, L3, and L4 are input to the arithmetic circuit 31, and are calculated from the arithmetic circuit 31 according to the following arithmetic expression. Two AC output signals each having an amplitude indicating sine and cosine function characteristics corresponding to (that is, two AC output signals having amplitude function characteristics that are 90 degrees out of phase with each other) are generated.
Vs−Vsa = (P0 + sin θ) sin ωt− (P0−sin θ) sin ωt
= 2sinθsinωt
Vc−Vca = (P0 + cos θ) sin ωt− (P0−cos θ) sin ωt
= 2 cos θ sin ωt

  Thus, two AC output signals (sin θ sin ωt and cos θ sin ωt) similar to the resolver having two periodic amplitude functions (sin θ and cos θ) corresponding to the rotation angle θ of the detection target rotation axis MJ are generated. be able to. That is, it is possible to generate two AC output signals (sin θ sin ωt and cos θ sin ωt) having two periodic amplitude functions (sin θ and cos θ) that swing positively and negatively with the middle point of the increase / decrease change as a zero point. FIG. 3B schematically shows this state only for the θ component (here, the component at time t is not shown). Thus, compared with a conventional resolver, in the present invention, only a primary coil needs to be provided, and a secondary coil for induction output is unnecessary, so the coil configuration is simple and the rotation of a simple structure is achieved. A mold position detecting device can be provided. In addition, in order to take out the voltage difference between the terminals of each coil for each coil pair, the sensor coils L1 and L3 are differentially connected without using the special arithmetic circuit 31, and the sensor coil L2 is used. And L4 may be differentially connected to each other so that output AC signals corresponding to the respective differences “Vs−Vsa” and “Vc−Vca” are obtained.

  A phase detection circuit (or amplitude phase conversion means) 32 measures the phase component θ of the amplitude functions sin θ and cos θ in the AC output signals sin θ sin ωt and cos θ sin ωt output from the arithmetic circuit 31 and detected by the phase detection circuit (or amplitude phase conversion means) 32. The rotational position θ can be detected by absolute. The phase detection circuit 32 may be configured using, for example, the technique disclosed in Japanese Patent Application Laid-Open No. 9-126809 related to the applicant's application. For example, the first AC output signal sin θ sin ωt is electrically shifted by 90 degrees to generate the AC signal sin θ cos ωt, and by adding and subtracting the second AC output signal cos θ sin ωt, sin (ωt + θ) and sin (ω ωt−θ), and two AC signals (signals obtained by converting phase component θ into AC phase shifts) that are phase-shifted in the leading and lagging directions according to θ are generated, and the phase θ is measured. Rotational position detection data can be obtained. Alternatively, a known RD converter used for processing the resolver output signal may be used as the phase detection circuit 32. The detection processing of the phase component θ in the phase detection circuit 32 is not limited to digital processing, and may be performed by analog processing using an integration circuit or the like. Further, after digital detection data indicating the rotational position θ is generated by the digital phase detection process, this may be converted to analog to obtain analog detection data indicating the rotational position θ. Of course, the output signals sin θ sin ωt and cos θ sin ωt of the arithmetic circuit 31 may be output as they are without providing the phase detection circuit 32. For example, when a three-phase signal similar to synchro is output from the arithmetic circuit 31, such an application form is possible.

  In the embodiment described above, the arrangement of the sensor coils L1, L2, L3, and L4 is only provided within a limited predetermined angular range (60 degree range) within one rotation. Therefore, the size of the sensor head SH does not have to be as shown in FIG. 1, and can be a size corresponding to a narrower range. Then, even if there is an obstacle in a predetermined range of the sensor rotor plate RP, the detection device can be installed avoiding this. Moreover, since the rotational position can be detected simply by attaching the sensor rotor plate RP as described above to the rotating body and arranging the sensor head SH in accordance with the sensor rotor plate RP, even with an existing rotating body, It becomes possible to easily provide a rotary position detecting device. As described above, the rotary type position detecting device according to the present invention is installed in a case where the rotary type position detecting device is installed later in an existing machine, or in an automobile engine motor or the like in which machinery is densely packed within a predetermined range. This is particularly effective when That is, when an obstacle already exists in a predetermined rotation angle range of the rotation axis MJ and it is impossible to install a conventional rotary position detecting device having a size corresponding to one full rotation, the obstacle It is advantageous because it can be dealt with by installing the rotary type position detecting device according to the present invention to a place in an angular range where no exists. Of course, in any of the embodiments, the detection target rotation axis MJ itself may be capable of continuous rotation of one full rotation or more, or only in a limited angular range of less than one rotation ( That is, it may be one that reciprocates.

In the detection apparatus according to the present invention, the position detection is performed by the magnetic action in the sensor head SH. Therefore, when undesired magnetism is exerted from the outside, the position detection accuracy may be adversely affected. In order to cope with this point, according to one embodiment, a magnetic shield member that shields magnetism from the outside is provided around the sensor head SH. In particular, when the position detection device according to the present invention is applied to an engine motor for an electric vehicle as described above, the vehicle engine motor has a large output and has a large amount of magnetic leakage to the outside. Magnetic shield measures need to be taken. 4 and 5 show an embodiment in which such a magnetic shield measure is taken.
FIG. 4A is a cross-sectional view showing an embodiment in which the entire sensor head SH including a plurality of detection units S1 to S4 (shown simply as S in FIG. 4) as shown in FIG. 1 is covered with a housing K made of a magnetic material. It is a schematic diagram. In this case, an external magnetic circuit is formed through the magnetic body of the housing K, and can be shielded so that the external magnetism does not enter the internal detection unit S. In this case, the entire magnetic core C of each detection unit S may be covered with a diamagnetic material (nonmagnetic good conductor such as copper, aluminum, or brass) A. The external magnetism that leaks into the detection unit S is attenuated by the external magnetism being attenuated by eddy current loss at the location of the diamagnetic material (non-magnetic good conductor). Therefore, it becomes possible to detect the accurate rotational position. FIG. 4B is a schematic cross-sectional view showing a modification of the magnetic coil C, and shows an example in which a magnetic core C independent of the sensor coil L is arranged. As shown in FIG. 4B, without using the magnetic core C formed in the shape of the letter “C” (see FIG. 1C) as the magnetic core C, it simply has a cylindrical shape or a rectangular parallelepiped shape. A magnetic core C formed in a shape may be used, and in this way, the sensor head SH can be made smaller and simpler, so that it is advantageous to detect the rotational position by installing in a narrow place. There is an advantage that it can be a device.

  The end of the magnetic core C of the detection unit S in the sensor head SH described above is directed in the thrust direction of the sensor rotor plate RP. However, the present invention is not limited thereto, and is directed in the radial direction. You may arrange in. FIG. 4C is a schematic cross-sectional view showing an example in which the magnetic core C of the sensor coil L is arranged and oriented so as to be oriented in the radial direction of the sensor rotor plate RP. In FIG. 4C, the same reference numerals as those in FIGS. 4A and 4B denote elements having the same function, and thus the above description is used and the same description is not repeated. 4C, the end of the magnetic core C of the sensor coil L is directed inward in the radial direction of the sensor rotor plate RP and faces the outer peripheral side surface of the sensor rotor plate RP through a gap. . In this case, because of the predetermined shape of the sensor rotor plate RP (for example, an appropriately designed shape such as 6 teeth or 6 petals as shown in FIG. 1A), the end of the magnetic core C and the sensor rotor plate The distance of the air gap formed in the radial direction with the outer peripheral side surface of the RP changes according to the rotational position. Due to the change in the opposing gap distance, the amount of magnetic flux penetrating the sensor coil L through the magnetic core C changes, so that the self-inductance of the sensor coil L changes and the impedance of the sensor coil L changes. Therefore, the rotation position can be detected in the same manner as in the embodiment shown in FIG. In the case of FIG. 4C, the axial length of the outer peripheral side surface of the sensor rotor plate RP is made somewhat longer. As a result, even if the sensor rotor plate RP is somewhat mechanically shaken in the thrust direction, the distance of the gap formed in the radial direction between the end of the magnetic core C and the outer peripheral side surface of the sensor rotor plate RP is as follows. It does not change and detection accuracy does not decrease. Therefore, even in this case, in an environment or machine in which the sensor rotor plate RP is likely to cause mechanical shake in the thrust direction, it is possible to detect the rotational position without being affected by mechanical shake in the thrust direction. There is.

  In the above-described example, each detection unit S is individually covered with the diamagnetic material (nonmagnetic good conductor) A. However, as another configuration example of the magnetic shield member, the housing K made of a magnetic material is used. The entire surface may be covered with a diamagnetic material such as copper. In this case, a thin layer made of a diamagnetic material may be formed on the surface of the housing K, for example, by plating the surface of the housing K made of a magnetic material with copper. An example in which such a magnetic shield measure is taken is shown in FIG. The entire sensor head SH including the plurality of detection units S1 to S4 is covered with a housing K made of a magnetic material K1, and a thin layer of a diamagnetic material K2 such as copper is applied to the surface of the housing K by plating or the like. In the example of FIG. 5, the base K3 of the housing K is formed of a nonmagnetic nonconductive material such as plastic, and the magnetic body K1 can be made light and thin by increasing the strength. The magnetic cores of the detectors S1 to S4 are of the same type as that shown in FIG. 4B, such as a cylindrical shape or a rectangular shape, or a “C” shape (FIG. 4A). Any of the types formed in the reference) may be used. Note that a nonmagnetic good conductor layer may be formed on the rear surface of the housing K, that is, between the housing K and the casing portion K3. In the example shown in FIGS. 4A and 4B, the housing K may be covered with a nonmagnetic and highly conductive material (eg, copper-plated).

  The technical idea of installing a magnetic shield member made of a material having non-magnetic good conductivity and shielding external magnetism by eddy current loss at the location of the magnetic response member is the housing K of the sensor head SH as described above. However, the present invention is not limited to the example in which the magnetic shield is provided, and can be realized by applying the magnetic shield to the rotor portion 21 as shown in FIG. In FIG. 6, the rotational position detection device includes a stator portion 23 including a coil portion, a rotary shaft 20 made of a magnetic material to which a rotational motion to be detected is given, and a predetermined magnetic response member attached to the rotary shaft 20. A rotor portion 21 having a shape, and the distance of the gap between the rotor portion 21 and the coil portion changes according to the rotation position according to the rotation of the rotary shaft 20, and according to the change, the distance The impedance of the coil section is changed, and an output signal corresponding to the impedance change is generated. As the specific configuration of the rotational position detection device, any known configuration may be used. The characteristic feature of this embodiment is that a joining portion for fixing the rotor portion 21 to the rotating shaft 20 is constituted by a magnetic shield member 22 made of a diamagnetic material (for example, copper). Thus, the external magnetic Φ leaking to the rotor portion 21 through the rotating shaft 20 is attenuated by eddy current loss at the magnetic shield member 22 and leaks to the magnetic circuit for detection of the rotor portion 21 and the stator portion 23. The external magnetism is shielded. Therefore, accurate position detection without being affected by external magnetism is possible. Also in the apparatus as shown in FIG. 6, a magnetic shield member for shielding magnetism from the outside to the coil portion may be further provided around the coil portion of the stator portion 23.

When a good conductor such as copper is used as the magnetic response member, the inductance of the coil decreases due to eddy current loss, and the voltage between the terminals of the coil decreases according to the proximity of the magnetic response member. . In this case, the position detection operation can be performed in the same manner as described above. Moreover, you may use the hybrid type thing which combined the magnetic body and the conductor as a magnetic response member.
In the type that detects the rotational position of the movement that swings within a rotation range of less than one rotation, the magnetic response member (the sensor rotor plate RP in the above-described embodiments) is used in each of the above embodiments. The sensor head SH that is fixed and on which the sensor coils L1, L2, L3, and L4 are arranged may be moved according to the displacement of the detection target.
In the above embodiment, the number of output AC signals (number of phases) is two phases of sine and cosine (that is, resolver type), but it is of course not limited to this. For example, there may be three phases (the amplitude function of each phase is, for example, sin θ, sin (θ + 120), sin (θ + 240)).

As a method of AC excitation of the sensor coil, a known two-phase excitation method in which at least two sensor coils are separately excited with sin ωt and cos ωt can be used. However, the one-phase excitation as described in the above embodiment is superior in various aspects such as simplification of the configuration and temperature drift compensation characteristics.
In the present invention, the voltage generated in the coil or the voltage between the terminals of the coil is not necessarily limited to the voltage detection type circuit configuration, and should be interpreted broadly. The range to be adopted is also included in the scope. In short, any circuit configuration that can generate and detect an analog voltage or current corresponding to a change in the impedance of the coil may be used.

  As described above, according to the present invention, it is sufficient to provide only the primary coil, and the secondary coil is not necessary. Therefore, it is possible to provide a rotary position detecting device having a small and simple structure. Also, by calculating the output signal of the coil, it is possible to obtain an output signal indicating the amplitude coefficient characteristic of the true sine function or cosine function in which the amplitude coefficient component swings positively or negatively, so that the coil configuration is simple, It is possible to provide a rotary position detecting device having a small and simple structure. In addition, it is possible to provide a rotary position detecting device capable of accurate position detection without being affected by external magnetism.

SH Sensor heads S, S1, S2, S3, S4 Detectors L, L1, L2, L3, L4 Sensor coils C, C1, C2, C3, C4 Magnetic core P Body plate RP Sensor rotor plate (magnetic response member)
T Mounting screw M Motor MJ Rotating shaft K Housing SR Shield ring 20 Rotating shaft 21 Rotor 22 Magnetic shield member 23 Stator 30 AC source 31 Arithmetic circuit 32 Phase detection circuit

Claims (1)

A coil unit including a plurality of coils excited by an AC signal, wherein each of the coils is mounted on an independent magnetic core, and each coil and magnetic core set is physically separated from another set. The coil and the magnetic core are each separated from each other in a predetermined relative positional relationship, from a predetermined partial rotation angle range of less than one rotation of the detection target rotation shaft. said coil portion formed by fixedly arranged against the fixing member comprising,
A magnetic response member provided on the rotation shaft so as to be displaced relative to the coil portion, wherein a relative position of the magnetic response member and the coil portion changes according to a rotation position of the rotation shaft. And a magnetic response member configured to change the impedance of each coil in accordance with the relative position, and obtaining rotational position detection data of the rotating shaft based on an output voltage corresponding to the impedance of each coil. A rotary type position detecting device.

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