JP2001235307A - Rotary type position detecting apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make small and simplify a detecting apparatus. SOLUTION: Coils 11 and 12 which are excited by a predetermined ac signal are arranged in a stator portion 10 and no secondary coil is provided. A rotor portion 20 is provided with a magnetism-responsive member 21 made of a magnetic body or an electrical conductor of a predetermined shape such that the impedance of each of the coils 11 and 12 is varied depending on a rotational position θ. As the impedance varies, the terminal-to-terminal voltage of each of the coils 11 and 12 increases or decreases over a predetermined range of rotational angles. A reference voltage corresponding to the mid point of the increase or decrease is generated by an ac-excited coil 13 provided in a position where it is unaffected by the rotational position θ, and the reference voltage is computed with a voltage taken out of each of the coils 11 and 12, whereby first and second ac output signals, sinθsinωt and cosθsinωt, are generated having first and second periodical amplitude functions as amplitude factors which oscillate toward the positive and negative sides with a zero point serving as the center. The rotational position θ is detected from this amplitude phase component θ.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary type position detecting device comprising a coil which is AC-excited and a magnetic material or a conductor relatively displaced with respect to the coil. It is suitable for detecting a rotational position over an angle range. In particular, an output AC signal showing an amplitude function characteristic of a plurality of phases using only a primary coil excited by one-phase AC is used in accordance with a rotational position to be detected. And what it produces.

[0002]

2. Description of the Related Art As an inductive type rotational position detecting device, a device which generates a two-phase output (a sine phase and a cosine phase output) by a one-phase excitation input is known as a "resolver". Those that produce phase outputs (three phases shifted by 120 degrees) are known as "synchros". The oldest type conventional resolver has a secondary winding of two poles (sine and cosine) orthogonal to each other at a mechanical angle of 90 degrees on the stator side and a primary winding on the rotor side. Things. This type of resolver is disadvantageous because it requires a brush to make electrical contact with the primary winding of the rotor. On the other hand, a brushless resolver that does not require a brush is also known. The brushless resolver is provided with a rotary transformer instead of a 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 the reduction in size. The increase in the number of parts leads to an increase in manufacturing costs.

On the other hand, a primary winding and a secondary winding are arranged on a plurality of salient poles on the stator side, and the rotor is made of a magnetic material having a predetermined shape (an eccentric shape, an elliptical shape, or a shape having protrusions). Then, based on the gap between the stator salient pole and the rotor magnetic body changing according to the rotational position, a magnetoresistance change according to the rotational position is generated, and an output signal corresponding to this is obtained. 2. Description of the Related Art A non-contact type variable magnetic resistance type rotational position detecting device has been known as a product name “Micro Shin” in old times. Further, a rotational position detecting device based on the same variable magnetoresistance principle is disclosed in, for example, Japanese Patent Application Laid-Open No. 55-46862.
This is shown in JP-A-55-70406 and JP-A-59-28603. 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 indicates the voltage level of the output signal). ) Are known. For example, when the phase method is adopted, the primary windings arranged at different mechanical angles, such as a two-phase excitation input or a three-phase excitation input, are excited in a plurality of phases shifted in phase, and an electric power is supplied according to the rotational position. A single-phase output signal having a shifted phase angle is generated. When the voltage method is adopted, the relationship between the primary winding and the secondary winding is opposite to that of the above-mentioned phase method, and a single-phase excitation input produces a plurality of phase outputs as in the above-mentioned "resolver".

In a rotational position detecting device such as a "resolver" which generates a plurality of phase outputs by one-phase excitation input, it is typically configured to generate a two-phase output of a sine phase output and a cosine phase output. . Therefore, the conventional non-contact type
In the variable magnetic resistance type resolver type rotational position detecting device, at least the stator has a four-pole configuration, each pole is arranged at intervals of 90 degrees in mechanical angle, and the first pole is a sine phase. A second pole separated by 90 degrees is a cosine phase, a third pole further separated by 90 degrees is a minus sine phase, and a fourth pole further separated by 90 degrees is a minus cosine phase. In this case, the rotor is made of a magnetic material or a conductor, and the shape thereof is a periodic shape such as an eccentric circular shape, an elliptical shape, or a gear shape in order to cause a magnetic resistance change according to the rotation of each stator pole. Formed. And
Each stator pole is provided with a primary coil and a secondary coil,
When the gap between each stator pole and the rotor changes in accordance with the rotational position of the rotor, the magnetic resistance of the magnetic circuit passing through the stator pole changes, and based on this, the primary coil and the secondary coil in the stator pole change. The degree of magnetic coupling during the rotation varies in accordance with the rotational position, and an output signal corresponding to the rotational position is induced in the secondary coil. The peak amplitude characteristic of the output signal of each stator pole is periodic. Shows function characteristics.

[0005]

The above-mentioned conventional non-contact, variable reluctance type resolver type rotational position detecting device is a primary-secondary induction type in which a primary coil and a secondary coil are provided. Because of that, the number of coils increases, and therefore,
There is a limit in reducing the size of the structure and a limit in reducing the cost. Furthermore, since the conventional rotation position detecting device has a configuration in which a plurality of stator poles are arranged at equal intervals throughout one rotation, there is a limit in an applicable place and space due to a structural limitation. Further, in the conventional rotational position detecting device, even when a two-phase output of sine and cosine is obtained, the stator cannot have a simple two-pole configuration and must have a four-pole configuration. However, there is a limit in miniaturizing the structure.

SUMMARY OF THE INVENTION The present invention has been made in view of the above, and has as its object to provide a rotary type position detecting device having a small and simple structure. In addition, the present invention provides a rotary type position detection device that can widen the range of usable phase angles, and can detect with high resolution even when the displacement of a detection target is minute, and can easily compensate for temperature characteristics. What you want to do.

[0007]

According to a first aspect of the present invention, there is provided a rotary position detecting apparatus comprising: a coil portion having at least one coil excited by an AC signal; A magnetically responsive member arranged to be relatively rotationally displaced, wherein a relative rotational position between the member and the coil portion changes in accordance with the rotation of the detection target, and the coil rotates in accordance with the relative rotational position. A voltage between the terminals of the coil increases or decreases while the relative rotational position changes over a predetermined rotation angle range based on the impedance change, and a predetermined reference voltage is generated. A circuit and a voltage generated in the coil are extracted and calculated with the reference voltage to generate at least two AC output signals having a predetermined periodic amplitude function as an amplitude coefficient. A calculation circuit, wherein the periodic amplitude function of the AC output signal comprises a what is different by a predetermined phase in the cycle characteristics.

[0008] The magnetic response member typically includes at least one of a magnetic material and a conductor. When the magnetic response member is made of a magnetic material, as the degree of proximity of the member to the coil increases, the inductance of the coil increases, the electrical impedance of the coil increases, and the voltage (ie, terminal) generated in the coil increases. Voltage) increases. Conversely, as the degree of proximity of the magnetically responsive member to the coil decreases, the inductance of the coil decreases and the electrical impedance of the coil decreases,
The voltage between the terminals of the coil decreases. In this way, the voltage between the terminals of the coil increases or decreases while the relative rotation position of the magnetic response member with respect to the coil changes over a predetermined rotation angle range with the rotation of the detection target.

Here, the AC signal flowing through the coil is sin
When the amplitude coefficient component generated by the increase / decrease change is represented by a function A (θ) using the rotation angle θ as a variable, the voltage between the terminals of the coil can be represented by A (θ) sinωt. In this case, the amplitude coefficient component A (θ) increases or decreases with rotation, but its value is only a positive value. For example, assuming that the curve of the increase / decrease change of the amplitude coefficient component A (θ) shows a characteristic approximating a sine curve, and assuming that the peak value is P, a typical expression is A (θ) = P ₀ + Psin θ. Is shown. Where P
₀ ≧ P. That is, the characteristic is such that the value of Psin θ is offset in the plus direction by a certain offset value P ₀ .

According to a first aspect of the present invention, a predetermined reference voltage is generated, a voltage between terminals of the coil is taken out,
By calculating with the reference voltage, an AC output signal having a predetermined periodic amplitude function as an amplitude coefficient is generated. For example, if the reference voltage is P ₀ sin
if .omega.t, subtraction by, A (θ) sinωt-P 0 sinωt = (P 0 + Psinθ) sinωt-P 0 sinωt = Psinθsinωt is obtained by calculating the output signal and the reference voltage of one coil, An output signal indicating the amplitude coefficient characteristic of a true sine function sin θ (or cosine function) in which the amplitude coefficient component swings positive or negative can be obtained. Therefore, according to the present invention, the coil configuration is simple. Further, according to the present invention,
Since only the primary coil needs to be provided and the secondary coil is unnecessary, a rotary type position detecting device having a smaller and simpler structure can be provided.

According to one embodiment of the present invention, the coil section has two coils arranged at a predetermined angle along the direction of change of the relative rotational position, and generates the reference voltage. The reference circuit (for example, P ₀₎ corresponds to the midpoint of the increase or decrease in the voltage generated in the coil.
sinωt), and the arithmetic circuit comprises:
By subtracting the reference voltage from the voltage between the terminals of the first coil of the two coils, a voltage offset corresponding to the reference voltage is eliminated, and the first voltage swings positive or negative around the zero point.
A first AC output signal (for example, sinθsinωt) having a periodic amplitude function as an amplitude coefficient is generated, and the reference voltage is subtracted from a voltage between terminals of a second coil of the two coils, thereby obtaining the reference voltage. A second AC output signal (for example, cos θ sin ωt) having a second periodic amplitude function that swings positive and negative around the zero point as an amplitude coefficient by eliminating a voltage offset corresponding to the voltage is generated. In this case, the sine phase output signal (sin θ sin ωt) and the cosine phase output signal (cos θ sin ωt) can be obtained just by providing two coils.

In another embodiment of the present invention, the arithmetic circuit performs predetermined first and second arithmetic operations using a voltage generated in one coil and the reference voltage, respectively. A first having a first amplitude function as an amplitude coefficient
, And a second AC output signal having a second amplitude function as an amplitude coefficient. In this case, as will be described in detail later, with respect to the rotational displacement in the predetermined limited mechanical rotation angle range, instead of the 360-degree full phase detection scale, the phase detection scale within the predetermined limited range (for example, (Range of 90 degrees) Position detection data can be obtained. That is, although only one coil is used and 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.

[0013] In one embodiment, the circuit for generating the reference voltage may include a coil (dummy coil) having a predetermined impedance disposed at a position not affected by the displacement of the magnetic response member. The use of such a dummy coil is useful for compensating the temperature drift characteristics of the detection coil provided in the coil unit. Of course, the circuit that generates the reference voltage is not limited to a coil, and a voltage generation circuit having a suitable configuration such as a resistor may be used.

In one embodiment, the coil portion is provided in a limited predetermined angle range within one rotation, and is suitable for detecting a rotational position in the limited predetermined angle range. It may be. Such a biased arrangement of the coil portions is effective when the rotary position detecting device according to the present invention is installed later in an existing machine. For example, if an obstacle already exists in a predetermined angle range of the rotation axis to be detected and it is impossible to install the stator coil over one full rotation, a position in the angle range where no obstacle exists does not exist. This is advantageous because it is possible to install a coil part having a biased arrangement.

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 in accordance with the proximity of the magnetic response member. Will be. Again,
Detection can be performed in the same manner as described above. As the magnetic response member, a hybrid type in which a magnetic body and a conductor are combined may be used.

A rotary position detecting device according to a second aspect of the present invention is a coil section having at least two pairs of coils excited by an AC signal, wherein each coil in one coil pair is a predetermined coil. A magnetically responsive member that is disposed at a distance corresponding to a rotation angle and that is disposed so as to be rotationally displaced relative to the coil portion, and the member and the coil are disposed in accordance with rotation of a detection target. The relative rotational position of the coil changes in accordance with the relative rotational position, and the impedance of the coil changes in accordance with the relative rotational position. The coil changes while the relative rotational position changes over a predetermined rotational angle range based on the impedance change. And the voltage between terminals of one coil pair shows a differential characteristic, and the voltage between terminals of each coil in one coil pair shows a differential characteristic. A circuit for extracting an AC output signal having a predetermined periodic amplitude function as an amplitude coefficient for each coil pair, extracting the voltage difference between terminals of the coil, and the periodic amplitude function of each AC output signal is The phase characteristics differ from each other by a predetermined phase.

According to the second aspect of the present invention, for example, when one coil pair has a sine phase, a change in the voltage between terminals of each coil in the one coil pair exhibits a differential characteristic. If one is to (P ₀ + Psinθ) sinωt, the other is a (P ₀ -Psinθ) sinωt.
When the difference between the two is taken out, (P ₀ + P sin θ) sin ωt − ｛(P ₀ −P sin
θ) sinωt｝ = 2Psinθsinωt. Assuming that the other coil pair has a cosine phase, the change in the voltage between the terminals of each coil in the coil pair exhibits a differential characteristic. When the difference between the two is taken out, (P ₀ + Pcos θ) sinωt− ｛(P ₀ −Pcos
θ) sin ωt｝ = 2P cos θ sin ωt. Such a differential combining principle is common to a conventionally known resolver, but the conventional resolver has a primary and secondary resolver.
Although the secondary coil is required, according to the second aspect of the present invention, only the primary coil needs to be provided, and the secondary coil is not required. A mold position detecting device can be provided.

[0018]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 shows an embodiment in which an amplitude change in a full range of electrical angles from 0 to 360 degrees can be obtained in two AC output signals each having an amplitude indicating a sine and a cosine function characteristic. FIG. 1A shows detection coils 11 and 1 on the stator unit 10 side in the rotary position detection device according to this embodiment.
2 is a schematic front view showing an example of a physical arrangement relationship between the magnetic member 2 and the magnetic response member 21 on the rotor section 20 side. FIG. 2B is a schematic side sectional view thereof, and FIG. FIG. 3 is a block diagram illustrating an example of an electric circuit and an electronic circuit related to the coils 11 and 12. Rotary shaft 22 to be detected
A magnetic response member 21 having a predetermined shape, for example, an eccentric disk shape, is attached to the rotor section 20 to form the rotor section 20. As an example, description will be made on the assumption that the material of the magnetic response member 21 is made of a magnetic material such as iron. The stator unit 10 is arranged so as to face the rotor unit 20 in the thrust direction.

The stator section 10 has two coils as detection coils.
It includes two coils 11 and 12. Each coil 11,
Numerals 12 are arranged on the stator substrate 14 at predetermined intervals in the circumferential direction, and this interval is, for example, 90 degrees with respect to the rotating shaft 22. The coils 11 and 12 are iron cores (magnetic cores) 15 and 16 respectively.
The magnetic flux passing through the coil is directed in the axial direction of the rotating shaft 22. Iron core 15,1 of each coil 11,12
6, a gap is formed between the end face of the rotor section 20 and the surface of the magnetic response member 21 of the rotor section 20.
It rotates without contact. The relative distance between the rotor section 20 and the stator section 10 is determined via a mechanism (not shown) so that the distance of the gap is kept constant. Due to the predetermined shape of the magnetic response member 21 of the rotor section 20, for example, an eccentric disk shape, the area of the end faces of the coil cores 15, 16 facing the magnetic response member 21 via the air gap changes according to the rotational position. I do. Due to the change in the facing gap area, the amount of magnetic flux passing through the coils 11 and 12 through the iron cores 15 and 16 changes, thereby changing the self-inductance of the coils 11 and 12. This inductance change is caused by each coil 1
It is also a change in impedance of 1,12.

The predetermined shape of the magnetic responsive member 21 of the rotor section 20 is appropriately designed so that an ideal sine function curve is obtained. For example, in order to obtain a curve of a sine function with one cycle for one rotation of the rotating shaft 22, the shape may be generally close to an eccentric disk as described above. It is known that the shape can be appropriately distorted or a shape similar to a heart shape, depending on the design conditions such as the shape of the coil and the iron core. How to design this shape is not the object of the present invention, and the shape of the rotor used in this type of known / unknown variable reluctance type rotation detector may be adopted. No further mention will be made. What is important is that the magnetic responsive member 21
In other words, the change in the inductance of each of the coils 11 and 12, that is, the change in the impedance according to the change in the rotational position of the rotor section 20 is the same as the curve of the ideal sine function. What is necessary is just to be designed appropriately as much as possible.

FIG. 2A shows an ideal sine function curve of the impedance change of one coil 11 with respect to the change of the rotation angle θ by A (θ). The curve of the ideal sine function of the change in the impedance of the other coil 12 with respect to the change in the rotation angle θ is indicated by B (θ). As can be seen, the other coil 12 is 9
Due to the arrangement shifted by 0 degrees, the curve B (θ) corresponds to a cosine function. Thus, each curve A (θ), B
Assuming that the midpoint of the increase / decrease change of (θ) is P ₀ and the amplitude of the shake is P, A (θ) = P ₀ + Psin θ B (θ) = P ₀ + Pcos θ It should be noted that there is no inconvenience in the description even if P is regarded as 1 and omitted, so that it will be omitted in the following description.

As shown in FIG. 1C, each coil 11,
Reference numeral 12 is excited with a constant voltage or a constant current by a predetermined one-phase high-frequency AC signal (tentatively indicated by sinωt) generated from an AC generation source 30. If the voltages between the terminals of the coils 11 and 12 are represented by Vs and Vc, respectively, these can be expressed as follows using the rotation angle θ to be detected as a variable. Vs = A (θ) sin ωt = (P ₀ + sin θ) sin
ωt Vc = B (θ) sin ωt = (P ₀ + cos θ) sin
ωt

The coil (dummy coil) 13 generates a reference voltage Vr.
(Θ) and B (θ) have a predetermined impedance corresponding to the midpoint P ₀ of increase / decrease change. For example, the coil 13 is shown in FIG.
As shown in FIGS. 3A and 3B, the detection coil 11 is disposed on the stator substrate 14 but is not affected by the displacement of the magnetic response member 21 of the rotor unit 20. , 12 have the same temperature drift conditions. This is useful for compensating for temperature drift errors of the detection coils 11 and 12. The coil (dummy coil) 13 is also AC-excited, and the voltage between its terminals, that is, the reference voltage Vr can be expressed as follows. Vr = P ₀ sinωt

The output voltage V of each of the coils 11, 12, 13
s, Vc, and Vr are input to the analog operation circuit 31,
The two AC output signals having amplitudes indicating the sine and cosine function characteristics corresponding to the detection target position θ from the analog arithmetic circuit 31 (that is, the amplitude functions shifted by 90 degrees from each other) 2 with characteristics
AC output signals) are generated. That is, the reference voltage Vr is subtracted from the output voltages Vs and Vc of the detection coils 11 and 12. Vs−Vr = (P ₀ + sin θ) sin ωt−P ₀ sin ωt = s
inθ sinωt Vc−Vr = (P ₀ + cos θ) sinωt−P ₀ sinωt = c
osθ sinωt

As described above, the detection coils 11, 1
By calculating the inter-terminal voltages Vs, Vc and the reference voltage Vr, the offset corresponding to the reference voltage Vr is eliminated, and two periodic amplitude functions (sin θ and cos θ) swinging positive and negative with the midpoint of the increase or decrease as a zero point. ) As an amplitude coefficient (sin θ sin ωt and cos θ si
nωt) can be generated. FIG. 2B schematically shows this state only for the θ component (the component at time t is not shown). As described above, the sine phase output signal (sin θ sin ω) similar to that of the conventionally known resolver is obtained only by providing the two detection coils 11 and 12.
t) and the cosine phase output signal (cos θ sin ωt) can be obtained.

The amplitude functions sin θ and co in the sine and cosine function AC output signals sin θ sin ωt and cos θ sin ωt output from the arithmetic circuit 31
The phase component θ of sθ is measured by a phase detection circuit (or amplitude phase conversion means) 32 to detect the rotational position θ to be detected.
Can be detected absolutely. The phase detection circuit 32 may be configured using, for example, a technique disclosed in Japanese Patent Application Laid-Open No. Hei 9-126809 filed by the present applicant. For example, the first AC output signal sinθsi
By electrically shifting nωt by 90 degrees, the AC signal s
inθcosωt is generated, and the second AC output signal cosθsinωt is added / subtracted and combined to obtain sin
(Ωt + θ) and sin (ωt−θ), two AC signals (signals obtained by converting the phase component θ into an AC phase shift) that are phase-shifted in the leading and lagging directions according to θ, By measuring θ, rotational position detection data can be obtained. Alternatively, an R-D converter used for processing a known 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, but may be performed by analog processing using an integration circuit or the like. Alternatively, after digital detection data indicating the rotational position θ is generated by the digital phase detection process, the digital detection data may be converted into analog data to obtain analog detection data indicating the rotational position θ. Of course, without providing the phase detection circuit 32, the output signal sin θ of the arithmetic circuit 31
sinωt and cosθsinωt may be output as they are. For example, in the case where the same three-phase signal as that of the synchro is output from the arithmetic circuit 31, such an application form is also possible. The block 33 on the back side of the substrate 14 of the stator unit 10 shown in FIG. 1B indicates that a necessary circuit may be mounted on this portion. For example, only the arithmetic circuit 31 or all the circuits in FIG. 1C including the AC generation source 30 and the phase detection circuit 32 may be mounted at the block 33. When the AC generation source 30 and the phase detection circuit 32 are constituted by digital circuits, they can be implemented as LSIs, so that the size can be reduced, and these circuits can be integrally mounted on the back side of the stator substrate 14.

Here, the compensation of the temperature drift characteristic will be described. The impedance of each of the coils 11, 12, 13 changes according to the temperature, and the output voltages Vs, Vc, V
r also fluctuates. For example, each voltage increases or decreases in one direction as shown by a broken line with respect to a solid curve in FIG. However, in the AC output signals sinθsinωt and cosθsinωt having the sine and cosine function characteristics obtained by arithmetically combining them, the temperature drift is completely compensated for by the calculation of “Vs−Vr” and “Vc−Vr”. As shown in (B), it is not affected by temperature drift. Therefore, in the embodiment in which the dummy coil 13 is used as the reference voltage Vr generation circuit, the value of the reference voltage Vr also changes (temperature drifts) according to the temperature change of the surrounding environment. The temperature drift characteristics of the detection coils 11, 12 are automatically compensated, and accurate position detection can be expected. Of course, the circuit for generating the reference voltage Vr is not limited to a coil, but may be a combination of a coil and a resistor, or only a resistor.
Other appropriate circuits may be used. For example, the curves A (θ) and B (θ) may be slightly troublesome before the detection operation.
Work to detect the maximum value and the minimum value of the curve A, to find the average value, to find the voltage corresponding to the midpoint P _{0 of the} increase and decrease of the values of the curves A (θ) and B (θ), Voltage Vr
May occur.

In the embodiment shown in FIG. 1, the ends of the iron cores (magnetic cores) 15 and 16 of the coils 11 and 12 are oriented in the thrust direction of the rotating shaft 22. However, it is needless to say that they may be arranged so as to be directed in the radial direction. FIG. 3 shows each of the coils 11, 1
2 shows an example in which two iron cores (magnetic material cores) 15 and 16 are arranged so as to be directed in the radial direction of the rotating shaft 22;
(A) is a schematic front view, and (B) is a schematic side sectional view. In FIG. 3, the same reference numerals as those in FIG. 1 denote elements having the same functions, and thus the above description will be referred to and the same description will not be repeated. In FIG.
The ends of the iron cores 15 and 16 of the coils 11 and 12 are
2 is directed inward in the radial direction, and faces the outer peripheral side surface of the magnetic response member 21 of the rotor section 20 via a gap. In this case, since the magnetic response member 21 of the rotor portion 20 has a predetermined shape (for example, an eccentric disk shape or a heart shape), the ends of the coil cores 15 and 16 and the outer peripheral side surface of the magnetic response member 21 are formed. The distance of the gap formed in the radial direction between the first and the second changes depending on the rotational position. Due to the change in the facing gap distance, the amount of magnetic flux passing through the coils 11 and 12 through the iron cores 15 and 16 changes, whereby the self-inductance of the coils 11 and 12 changes and the impedance of each coil 11 and 12 changes. . Therefore, the same operation as in FIG. 1 can be performed to detect the rotational position. In the case of FIG. 3, the axial length of the outer peripheral side surface of the magnetic response member 21 of the rotor section 20 is set to be somewhat longer. As a result, even if the detection target rotary shaft 22 slightly shakes in the thrust direction, the coil core 1
The distance of the air gap formed in the radial direction between the end of the magnetic response member 21 and the end of the magnetic response member 21 does not change, and the detection accuracy does not decrease. Therefore, the structure in which the air gap is formed in the radial direction as shown in FIG. 3 is used in an environment or a machine in which the detection target rotary shaft 22 is likely to mechanically shake in the thrust direction. This provides an advantage that a rotational position can be detected without being affected by mechanical shake. In other embodiments shown in FIG. 4 and subsequent drawings, it is needless to say that the same modifications as those in FIG. 3 can be made.

In each of the embodiments shown in FIGS. 1 and 3, the arrangement of the coils 11 and 12 is provided only in a limited predetermined angle range within one rotation (a range somewhat wider than 90 degrees). It is. Therefore, the size of the stator substrate 14 is as shown in FIG.
It is not necessary that the width be large enough to correspond to the full rotation of the rotor unit 20 as shown in FIG. 3, but to be a size corresponding to a limited range of approximately a half rotation quantile as shown in FIG. it can. Then, even if the obstacle 40 is located at a location as shown in FIG. 4, the detection device can be installed avoiding the obstacle 40. Such an uneven arrangement of the coils 11 and 12 in the stator section 10 is effective when the rotary position detecting device according to the present invention is installed in an existing machine later. That is, if the obstacle 40 already exists in the predetermined rotation angle range of the rotating shaft 22 and it is impossible to install the stator unit 10 having a size corresponding to one full rotation, the obstacle 40 exists. It is advantageous that the stator unit 10 in which the coils 11 and 12 having a biased arrangement are arranged can be installed in a place in an angle range where the coils are not arranged. Of course, in any of the embodiments, the detection target rotation shaft 22 itself may be capable of continuous rotation of one full rotation or more, or may be rotated only in a limited angle range of less than one rotation ( That is, reciprocating swing)
May be used.

In the example of FIGS. 1 to 4, each of the coils 11, 12
Output signal sinθsinω obtained based on the output of
The phase component θ in the amplitude function at t and cos θ sinωt corresponds one-to-one with the mechanical rotation angle θ of the rotating shaft 22. However, not limited to this, the phase component θ in the amplitude function is n times or 1 times the mechanical rotation angle of the rotation shaft 22.
/ N times. As an example, n =
FIG. 5 shows an example in which the frequency is doubled. FIG. 5 is a schematic front view similar to FIG. 1A, in which the arrangement interval between the two coils 11 and 12 is set to approximately 45 degrees with respect to the rotation shaft 22, and the shape of the magnetic response member 21A of the rotor unit 20 is changed. For example, each coil 11 and 12 is designed to have a sine function-like impedance increase / decrease change of two cycles per one mechanical rotation of the rotating shaft 22 such as an ellipse. Thereby, the AC output signal si obtained based on the outputs of the coils 11 and 12 with respect to the mechanical rotation angle θ ′ of the rotation shaft 22 is
The phase component θ in the amplitude function at nθsinωt and cosθsinωt indicates a double value. That is, θ = 2θ ′. Various modifications are possible without being limited to FIG.

FIG. 6 shows that only one detection coil 11 is provided in the stator section 10, and two AC output signals sinθ are provided based on the output of the one coil 11 and the reference voltage Vr.
FIG. 6A shows an embodiment for forming a signal equivalent to sinωt and cos θ sinωt. FIG. 7A shows the physical arrangement of the detection coil 11 on the stator unit 10 and the magnetic response member 21B on the rotor unit 20 according to this embodiment. FIG. 1B is a schematic side sectional view showing an example of the relationship by a schematic front view, and FIG. 1C is a block diagram showing an example of an electric circuit and an electronic circuit related to the detection coil 11 on the stator unit 10 side. It is. In the case of this example, the magnetic response member 21B of the rotor section 20
Has a spiral cam shape, for example, and is designed such that the phase component θ in the amplitude function of the AC output signal shows a change in a range of approximately 90 degrees with respect to the mechanical rotation angle range of the rotating shaft 22. Due to the spiral cam shape of the rotor portion 20, it is somewhat unsuitable for detecting one full rotation of the rotary shaft 22, but a predetermined mechanical rotation of less than one rotation excluding the spiral cam-shaped step portion of the magnetic response member 21B. It is suitable for detecting a rotation position in a rotation angle range.

In the case of FIG. 6, the voltage V between terminals of the coil 11 is
As shown in FIG. 7, for example, s ′ has a characteristic that increases (or decreases) substantially linearly in one direction in a predetermined mechanical rotation angle range of less than one rotation of the rotation shaft 22. Of the changes in the voltage Vs 'between the terminals of the coil 11, a value that is twice the minimum value or a value Vm close to the minimum value is set as the reference voltage Vr', and is generated by the dummy coil 13. FIG.
As shown in (C), the output voltages of the coils 11 and 13 are input to the arithmetic circuit 31. Operation circuit 3 shown in FIG.
In FIG. 7, by subtracting half the voltage of the reference voltage Vr ′ (that is, Vm) from the voltage Vs ′ between the terminals of the coil 11 as described below, the voltage is reduced from a substantially zero level as indicated by a symbol Va in FIG. A first AC output signal having an increasing characteristic of the amplitude function is formed, and a reference voltage Vr ′ (that is, 2V
By subtracting the voltage Vs' between the terminals of the coil 11 from m), a second AC output signal having an amplitude function characteristic of a characteristic substantially decreasing from Vm as shown by a symbol Vb in FIG. 7 is formed. Va = Vs ′ − (Vr ′ / 2) Vb = Vr′−Vs ′

The amplitude function characteristics of these AC output signals in the range W shown in FIG. 7 can be equivalently associated with one quadrant (a range of 90 degrees) of the sine function and the cosine function. For example, the first AC output signal Va can be associated with a sine function, and equivalently, sin θs
inωt. Further, the second AC output signal Vb can be associated with a cosine function, and can be equivalently treated as cos θ sin ωt. However, the range of the phase component θ with respect to the predetermined mechanical rotation range W of the rotation shaft 22 is a range of 90 degrees. Therefore, the phase angle θ detected by the phase detection circuit 32 shown in FIG. 6C takes a value in the range of 0 to 90 degrees,
The rotation position in the second predetermined mechanical rotation range W is indicated by an absolute value.

As shown in FIG. 7, assuming that the first and second AC output signals Va and Vb exhibiting substantially linear amplitude change characteristics are associated with sin θ sin ωt and cos θ sin ωt, the amplitude characteristics sin θ and cos θ
Shows some non-linearity with respect to the mechanical rotation angle of the rotating shaft 22. That is, it does not show true sine and cosine function characteristics. However, the phase detection circuit 22 apparently converts the AC output signals Va and Vb into a signal sin having amplitude characteristics of sine and cosine functions, respectively.
The phase detection processing is performed using θ sin ωt and cos θ sin ωt. As a result, the detected phase angle θ does not show linearity with respect to the rotation angle of the rotation shaft 22 to be detected. However, in detecting the rotational position, the non-linearity between the detected output data (the detected phase angle θ) and the actual position to be detected often does not become a very important problem. In other words, it suffices if the position can be detected with a predetermined reproducibility. If necessary, the output data of the phase detection circuit 22 is subjected to data conversion using an appropriate data conversion table so that accurate linearity is obtained between the detected output data and the actual detection target position. Can be easily performed. Therefore, the AC output signals sinθsinωt and cosθsinωt having the amplitude characteristics of the sine and cosine functions referred to in the present invention do not have to indicate the true sine and cosine function characteristics, and as shown in FIG. It may be something like a triangular wave shape (having a linear slope). In short, it is only necessary to show such a tendency.

FIG. 8 shows an embodiment in which the reference voltage generation circuit is omitted and a coil pair that changes differentially is provided instead. FIG. 8A shows each coil on the side of the stator section 10 according to this embodiment. FIG. 1B is a schematic front view showing an example of the physical arrangement relationship between the magnetic response member 21 and the magnetic response member 21 on the rotor section 20 side.
3 is a schematic side sectional view thereof, and FIG. 3C is a block diagram showing an example of an electric or electronic circuit related to each coil on the stator section 10 side. In this embodiment, the stator 1
0, the coil 11A is provided around the iron core 15A at an angular position 180 degrees opposite to the sine output coil 11, and the coil 12A is inserted at an angular position 180 degrees opposite to the cosine output coil 12 at the 180 ° angle. The coil 13 is wound around 16A, and the reference voltage generating coil 13 is omitted. The shape of the magnetic response member 21 on the rotor section 20 side may be the same as the example of FIG. With this configuration, the impedance of each coil in one coil pair changes differentially, so that the increase or decrease in the voltage between terminals of each coil exhibits differential characteristics. That is, in the pair of the sine-phase coils 11 and 11A, the impedance change of the coil 11, that is, the output amplitude change is represented by “P ₀ + Ps
In θ ”, the other coil 1
The change in impedance of 1 A, that is, the change in output amplitude shows a function characteristic of “P ₀ −Psin θ” with respect to the rotation angle θ of the rotation shaft 22. Similarly, the cosine phase coils 12 and 1
In the pair of 2A, the impedance change of the coil 12, that is, the output amplitude change is “P ₀
+ Pcos θ ”, the impedance change of the other coil 12A, that is, the output amplitude change is“ P ₀ −Pcos θ ”with respect to the rotation angle θ of the rotating shaft 22.
It shows the function characteristic. Hereinafter, as described above, for convenience,
P is regarded as 1 and the description is omitted.

As shown in FIG. 8C, each coil 11,
11A, 12 and 12A are excited by a predetermined AC signal, and the respective terminal voltages Vs, Vsa, Vc and Vca are applied.
Indicates a magnitude corresponding to each impedance corresponding to the rotation angle θ as described below. Vs = the _{(P 0 + sinθ) sinωt Vsa} = (P 0 -sinθ) sinωt Vc = (P 0 + cosθ) sinωt Vca = (P 0 -cosθ) sinωt arithmetic circuit 31, as described below, each for each coil pair The voltage difference between the terminals of the coils is extracted, and an AC output signal having a predetermined periodic amplitude function as an amplitude coefficient is generated for each coil pair. _{Vs-Vsa = (P 0 +} sinθ) sinωt- (P 0 -sinθ) sinωt = 2sinθsinωt Vc-Vca = (P 0 + cosθ) sinωt- (P 0 -cosθ) sinωt = 2cosθsinωt

Therefore, similarly to the above-described embodiment, two alternating currents having two periodic amplitude functions (sin θ and cos θ) corresponding to the rotation angle θ of the rotation shaft 22 to be detected as amplitude coefficients, similar to a resolver. Output signal (sin θ sin
ωt and cosθsinωt) can be generated. Compared with the conventional resolver, in the present invention, only the primary coil needs to be provided, and the secondary coil for inductive output is not required. Therefore, the coil configuration is simple, and the rotary type position detecting device having a simple structure is provided. Can be provided. In order to take out the voltage difference between the terminals of each coil for each coil pair, the coils 11 and 11A are differentially connected without using the special arithmetic circuit 31, and the coils 12 and 12A are connected.
Are differentially connected to each other to obtain the difference “Vs−Vsa”.
And a circuit may be simply configured to obtain an output AC signal corresponding to “Vc−Vca”.

FIG. 9 shows that the stator 10 has four
An embodiment consisting of a coil configuration is shown. However, in FIG.
Iron core 15 of each coil 11, 11A, 12, 12A,
15A, 16 and 16A face the radial direction of the rotating shaft 22, that is, face the cam-like cylindrical side surface of the magnetic response member 21. On the other hand, FIG.
A circuit configuration similar to that described above may be applied.

FIG. 10 shows an embodiment in which the stator portion 10 has a four-coil configuration as in FIGS. 8 and 9, but the magnetic response member 21 which rotates together with the rotating shaft 22 has multiple teeth (4 in FIG. 9). Each of the coils 11, 11A, 1A has a shape such as a tooth) or a multi-petal (four petals in the figure) that causes a plurality of (N) cycles of magnetoresistance change per rotation.
2, 12A has a structure arranged within a narrow range of 1 / N rotation (that is, 360 degrees / N). In the example of the figure, four coils 11, 12, 11A, and 12A are set to “90” within the mechanical angle range of 360 degrees / N = 360/4 = 90 degrees.
Degrees / 4 = 22.5 degrees ". As in FIG. 9, the magnetic cores 15, 15 A, 16, and 16 A of the coils 11, 12, 11 A, and 12 A are oriented in the radial direction of the rotating shaft 22, and have a four-period change in unevenness per rotation 21 facing the side surface of the cam-shaped cylinder. A circuit configuration similar to that in FIG. 8C may be applied to this.
However, the obtained sine function sinθ and cosine function c
osθ has an accuracy of N = 4 times the actual mechanical angle of the rotating shaft 22. For example, assuming that the actual mechanical angle of the rotating shaft 22 is ψ, sin θ = sinNψ, cos θ = co
sNψ. The example of FIG. 10 has a structure in which the coils 11, 11A, 12, and 12A of the stator unit 10 are arranged in a narrow range of 1 / N rotation (that is, 360 degrees / N). Similarly, it is very suitable for applications where the stator mounting space is limited to a narrow range.

FIG. 11 is a view similar to FIG.
This embodiment has a two-coil configuration, and the cores 15, 16 of the coils 11, 12 are oriented in the radial direction of the rotating shaft 22, that is, opposed to the cam-like cylindrical side surface of the magnetic response member 21. . FIG. 8
A circuit configuration similar to (C) may be applied. In this example,
There is only a limited space between the gear 41 provided on the rotating shaft 22 and the obstacle 42 extending from below where the stator unit 10 is disposed. In view of this point, since the stator unit 10 has a configuration having only two coils 11 and 12 arranged at intervals of 90 degrees mechanical angle, as in the example of FIG. Upon
The limited mounting space can be easily accessed from the direction of arrow R, avoiding the obstacle 42.
As shown by the dotted line, a core for the dummy coil 13 may be arranged in the middle of the stator unit 10. In this case, in order to prevent the dummy coil 13 from being affected by the magnetic response member 21 of the rotor section 20, the dummy coil 13 is provided with a fixed inductance for generating a predetermined reference voltage. The core end of the coil 13 is masked with a magnetically responsive material such as iron or copper.

When a good conductor such as copper is used as the magnetic response member 21, the inductance of the coil is reduced due to eddy current loss, and the voltage between the terminals of the coil is reduced according to the proximity of the magnetic response member 21. Will decrease. Also in this case, the position detection operation can be performed in the same manner as described above. Further, as the magnetic response member 21, a hybrid type in which a magnetic body and a conductor are combined may be used.
In the case of the type that detects the rotational position of the swinging motion in a rotation range of less than one rotation, in each of the above embodiments, the magnetic response member 21 is fixed and the detection coil 1 is fixed.
You may make it move 1 and 12 according to the displacement of the detection target. In each of the above embodiments, the number of output AC signals (the number of phases) is two phases of sine and cosine (that is, resolver type), but is not limited to this. For example, three phases (the amplitude function of each phase is, for example, sin θ, sin
(Such as (θ + 120), sin (θ + 240))
It may be.

The method of AC excitation of the coil is as follows.
Each of at least two coils is sinωt and cosω
It is also possible to use a known two-phase excitation method in which excitation is separately performed at t. However, the one-phase excitation as described in the above embodiment has a simplified configuration and a temperature drift compensation characteristic.
Excellent in various aspects.

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, but should be interpreted in a broad sense. Those adopting a circuit configuration are also included in the scope. In short, an analog voltage or current is generated according to the change in coil impedance,
Any circuit configuration that can detect this can be used.

[0044]

As described above, according to the present invention, only the primary coil needs to be provided, and the secondary coil is not required. Therefore, it is possible to provide a rotary type position detecting device having a small and simple structure. it can. By calculating the output signal of one coil and the reference voltage, it is possible to obtain an output signal indicating the amplitude coefficient characteristic of a true sine function or cosine function in which the amplitude coefficient component swings positive and negative, so that the coil configuration is It is possible to provide a rotary type position detecting device that is simple, has a smaller size, and has a simpler structure.

[Brief description of the drawings]

FIG. 1 shows an embodiment of a rotary position detecting device according to the present invention, in which (A) shows an example of a physical arrangement relationship between a detecting coil on a stator part side and a magnetic response member on a rotor part side. (B) is a schematic side sectional view thereof,
(C) is a block diagram showing an example of a circuit related to the detection coil on the stator section side.

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

3A and 3B show another embodiment of the rotary position detecting device according to the present invention, wherein FIG. 3A is a schematic front view, and FIG.

4A and 4B show still another embodiment of the rotary position detecting device according to the present invention, wherein FIG. 4A is a schematic front view and FIG.

FIG. 5 is a schematic front view showing still another embodiment of the rotary position detecting device according to the present invention.

FIG. 6 shows one embodiment of a rotary position detecting device according to the present invention in which one detecting coil is used. FIG. 6 (A) shows a detecting coil on a stator part side and a magnetic response member on a rotor part side. An example of the physical arrangement relationship of the front schematic diagram,
(B) is a schematic side sectional view, and (C) is a block diagram showing an example of a circuit related to a detection coil on a stator portion side.

FIG. 7 is a diagram illustrating a detection operation of the embodiment of FIG. 1;

8A and 8B show an embodiment of a rotary type position detecting device according to the present invention of a type not using a reference voltage, wherein FIG. FIG. 4B is a schematic front view illustrating an example of a physical arrangement relationship, FIG. 4B is a schematic side sectional view, and FIG. 4C is a block diagram illustrating an example of a circuit related to a detection coil on a stator unit side.

FIG. 9 is a perspective view schematically showing the structure of another embodiment of the rotary position detecting device according to the present invention which does not use a reference voltage.

FIG. 10 is a perspective view schematically showing the structure of another embodiment of a high-resolution rotary type position detecting device according to the present invention.

FIG. 11 is a perspective view schematically showing a rotary type position detecting device according to another embodiment of the present invention in a state where it is attached to a target portion.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Stator part 11, 12, 11A, 12A Detection coil 13 Coil for generating reference voltage (dummy coil) 14 Stator substrate 15, 16, 15A, 16A Iron core (magnetic core) 20 Rotor part 21, 21A, 21B Magnetism Response member 22 Rotary axis AC generator 30 Analog operation circuit 31 Phase detection circuit 32

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2F063 AA35 CA34 CB01 CC04 DA05 DD03 DD05 EA03 GA03 GA33 GA36 KA01 LA03 2F077 CC02 FF03 FF13 FF39 QQ03 QQ13 TT06 TT52 TT82 UU07 VV02

Claims (9)

[Claims] 1. A coil unit having at least one coil excited by an AC signal, and a magnetic responsive member arranged to be rotationally displaced relative to the coil unit, The relative rotation position between the member and the coil portion changes in accordance with the rotation, and the impedance of the coil changes in accordance with the relative rotation position. A voltage generated in the coil that increases or decreases during a change over an angular range; a circuit that generates a predetermined reference voltage; and a voltage generated in the coil that is extracted and calculated with the reference voltage to obtain a predetermined voltage. An arithmetic circuit for generating at least two AC output signals having the periodic amplitude function as an amplitude coefficient, wherein the periodic amplitude function of each AC output signal is A rotation type position detection device comprising a phase characteristic that differs by a predetermined phase. 2. The coil unit according to claim 2, wherein the coil unit is disposed so as to be shifted by a predetermined angle along a direction in which the relative rotational position changes.
A circuit for generating the reference voltage, wherein the circuit for generating the reference voltage generates a reference voltage corresponding to a midpoint of increase or decrease in the voltage generated in the coil; By subtracting the reference voltage from the voltage generated in the first coil, a first AC output signal having an amplitude coefficient of a first periodic amplitude function swinging positive and negative at the midpoint of increase and decrease is generated, By subtracting the reference voltage from the voltage generated in the second coil of the two coils, a second AC output signal having, as an amplitude coefficient, a second periodic amplitude function that swings positive and negative at the midpoint of increase and decrease is generated. The rotary position detection device according to claim 1, wherein 3. The arithmetic circuit according to claim 1, wherein a predetermined first operation and a second operation are performed using a voltage of one coil and the reference voltage.
Are respectively generated to generate a first AC output signal having a first amplitude function as an amplitude coefficient and a second AC output signal having a second amplitude function as an amplitude coefficient. The rotary position detecting device according to claim 1. 4. The rotary position according to claim 1, wherein the circuit for generating the reference voltage includes a coil having a predetermined impedance disposed at a position not affected by the displacement of the magnetic response member. Detection device. 5. The coil unit according to claim 1, wherein the coil unit is provided in a limited predetermined angle range within one rotation, and detects a rotational position in the limited predetermined angle range. 3. The rotary position detecting device according to claim 1. 6. Each coil of the coil section includes a magnetic core, and the gap or the area of the gap between the magnetic core and the magnetic response member changes according to the rotation, so that the impedance of the coil changes. The rotary position detection device according to claim 1, wherein the rotation type position detection device is generated. 7. An end of the magnetic core of each coil of the coil portion is oriented in a thrust direction of a rotating shaft, and a gap with the magnetic response member is formed in the thrust direction of the rotating shaft. A rotary position detecting device according to claim 6. 8. An end of a magnetic core of each coil of the coil unit is oriented in a radial direction of a rotation axis, and a gap with the magnetic response member is formed in a radial direction of the rotation axis. 7. The apparatus according to claim 6, wherein the rotational axis of the detection target is less susceptible to mechanical shake in the thrust direction.
3. The rotary position detecting device according to claim 1. 9. A coil section comprising at least two pairs of coils excited by an AC signal, wherein each coil in one coil pair is arranged at a distance corresponding to a predetermined rotation angle. A magnetically responsive member arranged to be rotationally displaced relative to the coil portion, wherein a relative rotational position between the member and the coil portion changes in accordance with the rotation of the detection target; The impedance of the coil is changed in accordance with the rotational position, and the voltage generated in the coil increases or decreases while the relative rotational position changes over a predetermined rotation angle range based on the impedance change. The difference between the voltage change of each coil in the pair showing the differential characteristic and the voltage difference generated in each coil for each coil pair is taken out. A circuit for generating an AC output signal having a periodic amplitude function as an amplitude coefficient for each coil pair, wherein the periodic amplitude function of each AC output signal differs by a predetermined phase in its periodic characteristic. Rotary position detection device equipped.