JPH0665966B2 - Rotational position detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention includes a primary winding and a secondary winding on the stator side,
The present invention relates to an inductive type (specifically, a variable reluctance type) rotational position detection device in which no winding is provided on the rotor side, and more specifically, a rotational position detection in which an induction coefficient change using eddy current loss as a parameter is obtained. Regarding the device.

[Conventional technology]

As an induction type rotational position detector of the type in which the primary winding and the secondary winding on the stator side are provided and the winding is not provided on the rotor side, a type that produces an output signal having a voltage level according to the rotational position is used. A rotary type differential transformer called a micro thin is known as one, and on the other hand, as a type that outputs an AC signal having an electrical phase angle according to the rotational position, the Japanese Patent Application Laid-Open No. Sho 57-57 The one disclosed in -70406 is known. All of these conventional detection devices change the magnetic resistance (change in permeability) due to the displacement of the magnetic body.
The induction coefficient of the coil was changed according to the above.

[Problems to be solved by the invention]

Therefore, the magnetic body must be processed into a predetermined shape to form the rotor, which is a troublesome process. Further, there is a problem in that there is a limit to miniaturization because the rotor is created by machining.

The present invention has been made in view of the above points, and it is an object of the present invention to provide a rotational position detection device which is easy to process and can be easily downsized.

[Means for solving problems]

A rotational position detecting device according to the present invention comprises a plurality of excitation phases excited by primary AC signals having a phase shift, and the primary AC signal is phased as a composite signal of induction signals in each excitation phase. A stator portion provided with winding means adapted to take out the shifted output signal, and provided so as to be relatively rotationally displaceable in the vicinity of the stator portion, and conductors are arranged in a predetermined pattern. The induction coefficient change with the eddy current loss caused by the body as a parameter is generated according to the relative rotational displacement in each phase of the stator, and the pattern of the conductor is formed and arranged by surface processing. And a rotor portion formed of the rotor portion. Is characterized in that said output signal indicating the phase shift is obtained.

[Action]

When a portion of the conductor pattern of the rotor portion enters the magnetic field generated by the winding means of the stator portion, eddy current flows in that portion,
The eddy current loss substantially increases the reluctance of the magnetic circuit of the winding means. The amount of eddy current changes according to the degree of penetration of the conductor pattern, and the magnetic resistance changes accordingly.
Therefore, the secondary output according to the relative rotational position of the conductor pattern of the rotor part with respect to the stator part is obtained in the winding means.

Since the eddy current has a property of flowing near the surface of the conductor, the conductor pattern to be provided in the rotor portion is not required to have a large thickness. Therefore, the conductor portion can be attached on the base material of the rotor portion in a predetermined pattern. This means that the rotor part is very easy to manufacture. That is, such a pattern of the relatively thin conductor portion can be formed relatively easily on the base material of the rotor portion by other appropriate surface processing technique such as plating, thermal spraying, pattern baking or etching. Therefore, it is possible to omit the tedious machining that is performed when the magnetic body is processed into a desired shape, and it is expected to reduce the manufacturing cost. Further, miniaturization becomes easy.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In FIG. 1, a stator part 1 has four pole parts corresponding to four phases A to D arranged at intervals of 90 degrees along the circumferential direction.
Includes 1A-1D. Primary winding W ₁ and secondary winding on each pole 1A-1D
W ₂ is wound respectively. Each pole part 1A to 1D of the stator part 1
The core material is made of a common magnetic core material. The end portions of the pole portions 1A to 1D face inward, and the rotor portion 2 is arranged in the space surrounded by the end portions with a gap. The rotor portion 2 includes a cylindrical base material 2a having a rotating shaft 3, and a conductor pattern 2b arranged on the cylindrical side surface of the base material 2a with a predetermined width. As shown in the side view in FIG. 2, the conductor pattern 2b has stator pole portions 1A to 1D.
Width that is approximately the same as or wider than the width of the edge of the (the wider one is preferable, but the width should not exceed approximately 180 degrees)
Consisting of a rectangular pattern with poles 1A to 1D and magnetic material
An eddy current path can be formed as shown by a line E in FIG.

The more the conductor pattern 2b faces the end faces of the stator pole portions 1A to 1D (for example, the state of phase C in FIG. 1 at the maximum), the more eddy current flows in the conductor 2b, and eddy current loss causes The magnetic resistance of the magnetic circuit passing through the pole portion (1c in the state of FIG. 1) facing the conductor 2b is increased. On the contrary, when the conductor pattern 2b is farthest from the magnetic field (for example, the state of phase A in FIG. 1), almost no eddy current flows. In this way, an eddy current flows in the conductor pattern 2b according to the proximity of the conductor pattern 2b to the magnetic field of each phase, and a magnetic resistance change due to this eddy current loss is generated in the magnetic circuit of each phase. An AC signal of a level corresponding to this magnetic resistance is induced in the secondary winding W _{2 of} each phase.

Since the magnetic poles 1A to 1D corresponding to the respective phases A to D are arranged at intervals of 90 degrees, the magnetic resistance change phases of the respective phases A to D caused by the change of the conductor pattern 2b are between adjacent phases. It is shifted by 90 degrees. Further, this change in magnetic resistance occurs in one cycle per one rotation of the rotor section 2. Therefore, each phase A to D
The level of the voltage induced in the secondary winding W ₂ of the rotor is expressed by the following formula depending on the rotation angle θ of the rotor: cos θ for A phase, sin θ for B phase, −sin θ for C phase, −sin θ for D phase. be able to.

To obtain an output signal corresponding to the rotational position of the rotor portion 2 by the phase shift system, A, a primary winding W ₁ and B Phase C electrical phase and a primary winding W ₁ of the D phase is 90 degrees Excitation is performed by alternating AC signals (for example, the A and C phases are sinusoidal signals sinωt
Respectively, and the B and D phases are respectively excited by the cosine wave signal cosωt). Then, the output signal of the secondary winding W ₂ is differentially added for A and C relative, and the secondary winding W ₂ is also for B and D relative.
_{The two} outputs are differentially added, and the differential output signals of each pair are added and combined to obtain the final output signal Y. Then, the output signal Y can be substantially expressed by the following simplified formula.

Y = sinωt cosθ− (−sinωt cosθ) + cosωt sinθ− (−cosωt sinθ) = 2sinωt cosθ + 2cosωt sinθ = 2sin (ωt + θ) A constant that is conveniently determined in accordance with various conditions in the above formula. If replaced by K, it can be expressed as Y = K sin (ωt + θ). Here, since θ corresponds to the rotational position of the rotor unit 2, the primary AC signal sinωt (or cosω)
The rotational position can be detected by measuring the phase shift θ of the output signal Y with respect to t).

In the case of FIG. 2, the conductor pattern 2b has a plane shape, but it may have a ring shape as shown in FIG. 3 and, in short, can form an eddy current path as shown by a line E. If you have.

In the embodiment shown in FIGS. 4 and 5, the end portions of the respective pole portions 4A to 4D and 4E of the stator portion 4 are oriented in the direction parallel to the rotation axis 3 and are 90 degrees in the circumferential direction. Each phase A to D arranged at intervals
Only the primary winding W ₁ is wound around the pole portions 4A to 4D corresponding to
Only the secondary winding W ₂ is wound around the pole portion 4E arranged in the center. In the rotor portion 5, a conductor pattern 5b is arranged at a predetermined position on a disk-shaped substrate 5a. The conductor pattern 5b has a fan-like shape with an angle of about 90 degrees, for example. The end portions of the stator pole portions 4A to 4E face the surface of the rotor portion 5 on which the conductor pattern 5b is arranged,
The magnetic flux passes from the pole parts 4A to 4D through the rotor part 5 and the central pole part
It flows to 4E. The eddy current path through conductor 5b is shown by line E in FIG. With this configuration, the operation is similar to that of FIG.

In the embodiment shown in FIG. 6 and FIG. 7, the pole portions 6A to 6D corresponding to the respective phases A to D of the stator portion 6 are U-shaped (or C).
Each of them is composed of an independent magnetic core for one phase. In the example of FIGS. 1 to 5, the magnetic path of each pole portion is connected to another pole portion through the rotor portion.
When an independent core is used for each phase as in the example of Fig. 7 and Fig. 7, a magnetic path is formed so as to connect from one end of each pole to the other end of the same pole through the rotor. To be done. Each pole
Primary and secondary windings W ₁ and W ₂ are wound around 6A to 6D, respectively.

The rotor portion 7 is composed of a disc-shaped conductor 7b that is eccentric with respect to the rotating shaft 3. As shown in FIG. 7, the rotor portion 7 is arranged such that its edge portion can enter between the two leg portions of each of the pole portions 6A to 6D. A state in which the conductor 7b penetrates deepest between the two legs of the pole portions 6A to 6D (for example, 6c in FIGS. 6 and 7).
Eddy current), the most eddy current flows and the magnetic resistance increases. Due to the eccentricity of the conductor 7b, the degree of penetration into each of the pole portions 6A to 6D changes according to the rotational position, whereby the same operation as in the embodiment of FIG. 1 is performed. Note that the eccentric disc of the rotor portion 7 does not need to be the conductor 7b as a whole, and is partially (for example, in a ring shape along the circumference of the disc) conductor so as to form an eddy current path. 7b may be used.

In the embodiment shown in FIGS. 8 and 9 as well, the stator portion 8
The pole portions 8A to 8D corresponding to the respective phases A to D are composed of an independent magnetic core for one phase having a U shape, and the pole portions 8A to 8D
A primary winding W ₁ and a secondary winding W ₂ are wound around each. The rotor portion 9 inserted in the space surrounded by the ends of the stator pole portions 8A to 8D includes a cylindrical base material 9a and a conductor arranged around the base material 9a in a spiral shape with a single-thread screw arrangement. 9b and. Ends of the stator pole portions 8A to 8D and the conductor of the rotor portion 9
The larger the area facing 9b, the more eddy current flows and the magnetic resistance increases. Since the conductor 9b is a spiral, the rotor portion 9
The area facing the stator pole portion changes according to the rotational position of the magnetic field, and the magnetic resistance changes accordingly. Therefore, the operation is similar to that of the embodiment shown in FIG.

In each of the above-mentioned embodiments, the cycle of magnetic resistance change in each stator pole portion is one cycle per one revolution, but in the embodiments shown in FIGS. 10 and 11, it is three cycles per one revolution. Each of the pole portions 10A to 10D of the stator portion 10 is composed of an independent magnetic material core for each phase of a U-shape, as described above, and has primary and secondary windings W ₁ and W _{2 respectively.} Is wound. The rotor portion 11 inserted in the space surrounded by the ends of the stator pole portions 10A to 10D has a cylindrical base material 11a.
And three conductors 11b arranged on its side surface with a width of about 60 degrees and spaced at intervals of about 60 degrees. Rotor part 11
Due to the three pieces of conductors 11b arranged on the circumferential surface of, the magnetic resistance change occurs in each of the stator pole portions 10A to 10D with a rotation range of 120 degrees as one cycle. Therefore, three cycles of magnetic resistance change occur per rotation.

The embodiment shown in FIGS. 12 and 13 produces two cycles of magnetoresistance change per revolution. Stator part
12 is eight pole parts 12A to 12D, 12 at intervals of 45 degrees in the circumferential direction.
It consists of ~ 12, and the same phase faces each other at intervals of 180 degrees. The rotor portion 13 includes an elliptic cylinder-shaped (this may be a true cylinder) base material 13a, and a ring-shaped conductor 13b wound around the longitudinal direction along the major axis of the elliptic cylinder. I am. Since the conductor 13b forms a short ring along the major axis of the elliptic cylinder, a certain pole portion (12A in the example of FIG. 12) is formed.
And 12) correspond to the short diameter part of the elliptic cylinder, the most eddy current flows according to the magnetic flux passing through the pole part.

The embodiment shown in FIGS. 14 and 15 also produces a change in magnetic resistance for two cycles per revolution. Stator part
Reference numeral 14 denotes eight pole portions 14A to 14D, 1 composed of independent magnetic cores.
4 to 14 are arranged at intervals of 45 degrees, and primary and secondary windings W ₁ and W ₂ are wound around each pole portion. As in Figure 12, 1
Two phases facing each other at an interval of 80 degrees are the same phase.
In the example of FIG. 12, the magnetic circuit is formed through the rotor portion 13 between two opposite phases (for example, the magnetic flux flowing from the pole portion 12A to the pole portion 12 through the rotor portion 13). In the example of FIG. 14, the magnetic circuit is formed so as to flow from one end of the same pole portion through the rotor portion 15 to the other end.

The rotor portion 15 inserted into the space surrounded by the stator pole portions 14A to 14 includes a cylindrical base material 15a and a conductor around the base material 15a which is spirally arranged in a two-thread screw arrangement. 15
b is provided. Due to the double thread structure, the change in the magnetic resistance due to the change in the facing area of the conductor 15b at a certain pole portion occurs in two cycles per rotation.

In each of the above-described embodiments, the conductor arranged in the rotor portion is made of a material having a relatively good conductivity as compared with the base material (for example, copper, aluminum, brass, or the like, or a material having a good conductivity such as those). A mixture of substances). Further, the base material of the rotor part may be either a magnetic material or a non-magnetic material, but if it is a magnetic material, it is convenient because the passage of magnetic flux is improved.

When the detection device of the present invention is operated by the phase shift method as described above, means for obtaining the phase shift θ between the output combined signal Y of the secondary coil and the reference AC signal sinωt (or cosωt) can be appropriately configured. . FIG. 16 shows an example of a circuit in which the phase shift θ is calculated by a digital amount. Although not shown in particular, the phase shift θ is obtained by calculating the time difference of the phase angle 0 ° between the reference AC signal sinωt and the output signal Y = K sin (ωt + θ) using an integrating circuit.
Can also be calculated in analog quantity.

In FIG. 16, the oscillator 32 is a circuit for generating the reference sine signal sinωt and the cosine signal cosωt, and the phase difference detection circuit 37 is a circuit for measuring the phase shift θ. The clock pulse CP oscillated from the clock oscillator 33 is the counter 30.
Is counted in. The counter 30 is, for example, modulo M (M
Is an arbitrary integer), and the count value is given to the register 31. A pulse Pc obtained by dividing the clock pulse CP by 4 / M is extracted from the 4 / M divided output of the counter 30,
It is given to the C input of the flip-flop 34 for frequency division. The pulse Pb output from the Q output of the flip-flop 34 is added to the flip-flop 35, the pulse Pa output from the output is added to the flip-flop 36, and the outputs of these 35 and 36 are supplied to the low-pass filters 38, 39 and the amplifiers 40, 41. Via, a cosine signal cos ωt and a sine signal sin ωt are obtained and applied to the primary winding W ₁ of each phase A to D. The M count in the counter 30 corresponds to the phase angle of 2π radians of these reference signals cosωt, sinωt. That is, one count value of the counter 30 is The phase angle in radians is shown.

The combined output signal Y of the secondary coils 2A to 2D is applied to the comparator 43 via the amplifier 42, and a square wave signal according to the positive / negative polarity of the signal Y is output from the comparator 43. In response to the rise of the output signal of the comparator 43, the rise detection circuit 44 outputs a pulse Ts, and the count value of the counter 30 is loaded into the register 31 in response to the pulse Ts.
As a result, the digital value Dθ corresponding to the phase shift θ is taken into the register 31. In this way, it is possible to obtain the data Dθ that indicates the rotational position within one rotation as an absolute value.

FIG. 16 is suitable for the four-pole type stator as shown in FIGS. 1 to 9, but the embodiment of FIGS. 10 to 15 similarly obtains rotational position data by the phase shift method. be able to. However, since the magnetic resistance change of 3 cycles per rotation occurs in the embodiment of FIGS. 10 and 11, the actual rotation angle θ
, Y = K sin (ωt + 3θ) is obtained, and the digital value Dθ absolutely specifies the rotational position within 1/3 rotation. Also, from FIG.
Since the embodiment shown in FIG. 15 causes the magnetic resistance change of two cycles per rotation, the output signal Y is Y = K sin (ωt + 2).
θ), and the digital value Dθ absolutely specifies the rotational position within 1/2 rotation.

The signal processing method is not limited to the phase shift method as described above,
Like a normal operation transformer, the differential output of the secondary coil may be rectified to obtain an analog voltage of a level according to the rotational position. In that case, the primary AC signals of the respective phases A to D may be common, and the pole portion may be only one of the A and C phases or the B and D phases.

The form of the conductor pattern arranged in the rotor portion is not limited to the above-mentioned one, and can be set arbitrarily in design. Further, the formation of the conductor pattern in the rotor portion may be performed by using an appropriate surface processing technique (for example, plating, thermal spraying, baking, painting, welding, vapor deposition, electroforming, photoetching, etc.). Recently, a microfabrication technique capable of forming even a fine pattern by using such a machining technique has been established, and thus a precise pattern can be formed by using such a technique. Further, in order to finish the surface of the rotor portion, it is advisable to coat the entire rotor portion with a suitable non-magnetic and non-conductive material on the conductor pattern.

FIG. 17 shows an example in which a pattern 2b is formed of a good conductor material such as copper around the base material 2a of the rotor part 2 and a surface coating 2c such as chrome plating is provided on the pattern 2b. As a pattern forming method in this case, a desired pattern 2b is formed by copper plating on the entire circumference of the base material 2a and then removing unnecessary parts by a removal technique such as etching to leave the copper plated parts remaining. To do so. Finally, a surface coating 2c such as chrome plating is applied for surface finishing. It is preferable to use a magnetic material such as iron for the base material 2a because it allows the magnetic flux to pass better. However, it is also possible to use a resin such as plastic or the like as the base material 2a. In that case, a metal film of copper or the like may be plated on the surface of the preformed plastic substrate 2a, or a metal film of copper or the like may be preformed by electroforming in the mold cavity, and then the plastic may be used. May be injection molded to be integrated with the metal film.

By the way, when the surface coating 2c is filled in the recesses between the patterns 2b as shown in FIG. 17, the coating 2c inevitably sinks at that portion, and the finished surface often does not become smooth. Therefore, as shown in FIG.
The depressions between the patterns 2b may be filled with an appropriate filling material 2d, and the surface coating 2c may be applied from above. As the filling material 2d, for example, nickel plating or the like can be used.

When the base material 2a is plated with a metal film such as copper and then etched in a desired pattern, the surface of the base material 2a may be attacked by the etching agent. Especially, when the base material 2a is a metal such as iron, the problem is large. In order to solve such a problem, as shown in FIG. 19, a predetermined substance having resistance to an etching agent is formed on the entire surface of the base material 2a.
It is preferable that a thin film of 2e (for example, resin) is formed, copper plating or the like is performed on the thin film, and then predetermined etching is performed to form the pattern 2b.

In each of the above-mentioned embodiments, the primary winding and the secondary winding for each phase in the stator part do not necessarily have to be separate windings. Sho 58-3950
It may be common, such as the one shown in No. 7.

Further, the stator portion is not limited to the 4-pole type or 8-pole type as described above, but may be any other suitable integer such as 3-pole type, 6-pole type or 12-pole type. In that case, because of the phase shift method, the primary coil exciting AC signal is
It is not a signal that is 90 degrees out of phase like a sine signal and a cosine signal, but sin ωt and sin (ωt-60) or sin (ωt−1)
20) or sin (ωt-240), such as an AC signal that is 60 degrees out of phase or an AC signal that is out of phase by a multiple of that,
In addition, an AC signal that is appropriately shifted by a phase angle is used.

〔The invention's effect〕

As described above, according to the present invention, the conductor pattern is arranged in the rotor portion, and the rotational position detection signal is obtained using the magnetic resistance change corresponding to the eddy current loss caused thereby as a parameter. It is possible to achieve the simplification and simplification of processing, and it can be expected to reduce the manufacturing cost.

[Brief description of drawings]

FIG. 1 is a radial sectional view showing an embodiment of a rotational position detecting device according to the present invention, FIG. 2 is a side view showing an example of a rotor portion in the embodiment, and FIG. 3 is a rotor in the embodiment. 4 is a side view showing a modified example of the portion, FIG. 4 is a schematic front view showing another embodiment of the present invention, FIG. 5 is a sectional view taken along the line VV of FIG. 4, and FIG. Fig. 7 is a schematic front view showing another embodiment, Fig. 7 is a sectional view taken along the line VII-VII in Fig. 6, Fig. 8 is a radial sectional view showing another embodiment of the present invention, and Fig. 9 is a sectional view. 8 is a sectional view taken along the line IX-IX of FIG. 8, FIG. 10 is a radial sectional view showing still another embodiment of the present invention, FIG. 11 is a side view of the rotor portion of FIG. 10, and FIG. FIG. 13 is a radial sectional view showing another embodiment of the present invention, FIG. 13 is a perspective view of the rotor portion shown in FIG. 12, and FIG. 14 is a radial sectional view showing yet another embodiment of the present invention. Figure 15 FIG. 14 is a sectional view taken along the line IV-IV in FIG. 14, and FIG. 16 is a circuit for operating the rotational position detecting device of the present invention by a phase shift method to measure the electrical phase shift amount according to the rotational position. 17 is a block diagram showing an example, and FIGS. 17 to 19 are cross-sectional views showing specific examples of a method of forming a conductor pattern in a rotor portion. 1,4,6,8,10,12,14 ...... Stator part, 1A ~ 1D, 4A ~ 4D, 6A ~
6D, 8A to 8D, 10A to 10D, 12A to 12,14A to 14 ...... Stator pole part, W ₁ …… Primary winding, W ₂ …… Secondary winding, 2,4,7,9,11 , 1
3,15 …… Rotor part, 2a to 15a …… Rotor part base material, 2b to 1
5b ... Conductor pattern of rotor part, 3 ... Rotating shaft.

Claims (1)

[Claims] 1. An output signal comprising a plurality of excitation phases excited by phase-shifted primary AC signals, and an output signal obtained by phase-shifting the primary AC signals as a composite signal of induction signals in each excitation phase. An eddy current generated by the conductor, which is provided with a winding unit that is designed to be taken out, and is provided so as to be capable of relatively rotational displacement in the vicinity of this stator unit and in which a conductor is arranged in a predetermined pattern. A rotor part formed by causing a change in an induction coefficient with a loss as a parameter in each phase of the stator in accordance with the relative rotational displacement, and forming and arranging the pattern of the conductor by surface processing. And a phase shift corresponding to a relative rotational position of the rotor portion in response to a change in induction coefficient of each phase of the stator corresponding to a relative rotational displacement of the rotor portion. Rotational position detecting device, characterized in that the force signal.