JPS61122504A - Detecting device for rotating position - Google Patents

Abstract

PURPOSE:To improve detection accuracy still more by the multiplier effect of the magnetic reluctance variation by the displacement of a magnetic substance part and the magnetic reluctance variation corresponding to the eddy current loss by the displacement of an electric conductor part. CONSTITUTION:The more the electric conductor part 2b is in the state of facing the end faces of stator pole parts 1A-1D, the more the eddy current is flowed into the part 2b by which the magnetic reluctance of a magnetic circuit passing through the pole parts facing the part 2b is increased. On the other hand, in the state that the pole parts 1A-1D face the part 2b, a gap between the pole parts and the magnetic substance part 2a of a rotor part 2 is a maximum and the magnetic reluctance of the magnetic circuit passing through the pole parts is relatively increased. Accordingly, the magnetic reluctance is multiplicatively increased and a level of the induced voltage of secondary winding W2 is multiplicatively attenuated. Then, as the part 2b is separated from a certain pole part 1A-1D, the gap between the pole part and the part 2a is shortened and the magnetic reluctance is reduced. Then, when the gap between the pole 1A and the part 2a is a minimum, the magnetic reluctance becomes minimum and the level of the induced voltage of the winding W2 of the pole 1A becomes maximum.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention includes a primary winding and a secondary winding on the stator side,
Regarding the induction type (specifically, variable magnetic resistance type) rotational position detection device that does not have a winding on the rotor side, in detail, the induction type that uses both magnetic resistance change (magnetic permeability change) and eddy current loss as parameters. The present invention relates to a rotational position detection device that enables highly accurate detection by synergistically obtaining coefficient changes.

[Conventional technology]

An inductive rotational position detector that has a primary winding and a secondary winding on the stator side and no winding on the rotor side is a type that generates an output signal with a voltage level depending on the rotational position. A rotary dynamic transformer called Microsin is known as a rotary motion transformer, and on the other hand, a type of transformer that outputs an alternating current signal with an electrical phase angle depending on the rotational position is disclosed in Japanese Unexamined Patent Publication No. 1986-57 filed by the present applicant. The one disclosed in No.-70406 is known. In all of these conventional detection devices, the induction coefficient of the coil is changed only in response to changes in magnetic resistance (changes in magnetic permeability) caused by displacement of the magnetic body.

[Problem that the invention seeks to solve]

Therefore, there was a limit to detection accuracy.

This invention was made in view of the above points, and
It is an object of the present invention to provide a rotational position detection device that can further improve detection accuracy.

[Failure to solve the problem]

The rotational position detection device according to the present invention includes a stator section which is excited by a primary alternating current signal and includes a winding means for taking out a secondary output, and a stator section arranged to be rotationally displaceable relative to the stator section. and a rotor section, wherein the rotor section changes the reluctance (in other words, the magnetic permeability) of the magnetism traveling back through the winding means in accordance with the relative rotational displacement with respect to the stator section. The shaped magnetic material part and the part where the magnetic resistance is relatively increased (in other words, the part where the magnetic permeability or permeance is relatively decreased) form an eddy current path for the magnetic flux. It is characterized in that it includes a conductor part which is relatively weakly magnetic or non-magnetic than the magnetic part and made of a relatively good conductor.

[Effect]

In the rotor portion, by providing a conductor portion corresponding to a portion where the magnetic resistance is relatively increased, eddy current loss occurs in that portion, thereby further increasing the substantial magnetic resistance. In this way, the induction coefficient changes using not only the magnetic resistance change (magnetic permeability change) due to the displacement of the magnetic body part but also the eddy current loss due to the displacement of the conductive body part (because the number of turns of the winding means and other conditions are fixed). (substantially equivalent to a change in magnetoresistance) is obtained synergistically. In other words, in the range where the magnetic resistance is relatively reduced (the range where the permeance is relatively increased), the eddy current loss due to the conductor part does not affect the voltage, and therefore the voltage is at a relatively sufficiently high level. can be guided to the secondary side. On the other hand, in a range where the magnetic resistance is relatively increased, eddy current loss occurs due to the conductor portion, and the increase in magnetic resistance is added, thus making it possible to further reduce the voltage level induced on the secondary side. .

In this way, the difference between the high level and low level of the secondary side induced voltage, that is, the change width of the secondary output with respect to displacement, can be made sufficiently large, which allows for highly accurate displacement detection. It becomes like this.

[Implementation row]

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

In FIG. 1, the stator part 1 is 90 mm along the circumferential direction.
It includes four pole portions 18 to 1D corresponding to four phases A-D arranged at intervals of degrees. Each pole part 1A to 1D has a primary winding W.
I and the secondary winding W2 are wound respectively. Stator part 1
The core material of each of the pole parts 1A to 1D is made of a common magnetic core material. The end portions of each of the pole portions 1A to 1D face inward, and the rotor portion 2 is disposed in a space surrounded by the end portions with a gap therebetween. The rotor portion 2 includes a cylindrical magnetic portion 2a that is eccentric with respect to the rotation axis B. Due to the eccentric shape of the magnetic body portion 2a, the magnetic resistance of the magnetic circuit passing through each pole portion 1A to 1D of the stator changes depending on the rotation angle. That is, the distance of the air gap between the cylindrical side surface of the magnetic body part 2a and the end of each pole part 1A to 1D changes according to the rotation angle θ, and due to the change in this gap, A change in magnetoresistance (or permeance) corresponding to one cycle of trigonometric functions is produced in each phase A-D.

The rotor part 2 is made of a weakly magnetic or non-magnetic material such as copper, and a part of the cylindrical side surface of the magnetic part 2a that is the shortest distance from the rotating shaft 6 (that is, a part where the magnetic resistance is relatively increased). It has a conductor portion 2b made of a conductor. As shown in the side view in FIG. 2, this conductor portion 2b has an area that is approximately the same as or somewhat larger than the area of the end portions of the stator pole portions 1A to 1D, and has a magnetic material portion. 2a, an eddy current path can be formed as shown by line E in FIG.

In a state in which the conductor portion 2b is more opposed to the end faces of the stator pole parts 1A to 1D (for example, in the state of phase C in FIG. 1 at the maximum), more eddy current is conducted than in the state (I) c)
The reluctance of the magnetic circuit passing through is increased. on the other hand,
As is clear from the foregoing, when the stator pole parts 1A to 1D face the conductor part 2b, the pole parts (first
In the figure, the gap between 1C) and the magnetic material portion 2a of the rotor portion 2 is the largest, and the magnetic resistance of the magnetic circuit passing through the pole portion is relatively increased. Therefore, the magnetic resistance is increased synergistically, and the level of the induced voltage in the secondary winding W2 at the pole portion is synergistically attenuated.

As the conductor portion 2b moves away from the stator pole portions 1A to 1D, the gap between the pole portion and the magnetic portion 2a narrows, and the magnetic resistance decreases.

Then, as in the A phase in FIG. 1, the magnetic resistance becomes the minimum when the gap between the pole part 1A and the magnetic body part 2a becomes the minimum, and the induced voltage of the secondary winding W2 in the pole part 1A decreases. level is maximum.

To schematically illustrate the above matter, the level of the induced voltage due to only the magnetic material portion 2a in the one-phase secondary winding W2 is as shown by the solid line in Fig. 3 with respect to rotational displacement in the range of one rotation (360 degrees). However, in a portion where this level is relatively attenuated, the level attenuation of the induced voltage due to the eddy current loss in the conductor portion 2b is multiplied as shown by the broken line. In this way, the range of change in the induced voltage level with respect to rotational displacement (for example, VLl, VL2) is greater when the synergistic effect of the magnetic portion 2a and the conductive portion 2b (VL2) occurs than when the magnetic portion 2a is present (VLl). becomes larger.

In the case of FIG. 2, the conductor portion 2b is planar, but it may also be ring-shaped as shown in FIG. All you have to do is stay there.

In the embodiment shown in FIGS. 5 and 6, the ends of each pole section 4A to 4D, 4E of the stator section 4 are oriented in a direction parallel to the rotation axis B, and are oriented at 90 degrees in the circumferential direction. Only the primary winding W is wound around the pole parts 48 to 4D corresponding to each phase A-D arranged at intervals, and the secondary winding W is wound around the pole part 4E arranged at the center.
Only 2 is wound. The rotor portion 5 includes a disc-shaped magnetic material portion 5a having an inclined surface, and this inclined surface faces the ends of the stator pole portions 4A to 4E. Magnetic part 5
In the large gap between a and the pole parts 4A to 4E,
A conductor portion 5b is provided.

The magnetic flux flows from each pole part 4A to 4D through the rotor part 5 to the central pole part 4E. The eddy current path flowing through the conductor portion 5b is indicated by line E in FIG.

This configuration operates in the same manner as in FIG. 1, and allows a synergistic increase in magnetic resistance at locations where magnetic resistance increases.

In the embodiment shown in FIGS. 7 and 8, the pole portions 6A to 6D corresponding to each phase A to D of the stator portion 6 are independent magnets for one phase of a U-shape (or a 0-shape). Each body consists of a core. In the examples shown in FIGS. 1, 2, 5, and 6, the magnetic path of each pole passes through the rotor and connects to another pole, but in the examples shown in FIGS. When an independent core is used for each phase as in the example shown, a magnetic path is formed from one end of each pole through the rotor to the other end of the same pole. A primary winding HWt and a secondary winding Wz are wound around each of the pole parts 6A to 6D, respectively.

The rotor portion 7 includes a disc-shaped magnetic part 7a that is eccentric with respect to the rotation axis 6, and a disc-shaped conductor that is eccentric with respect to the rotation shaft 6 at a position 180 degrees shifted from the magnetic part 7a. part,
7 b. As shown in FIG. 8, the rotor section 7 is arranged such that its edge can enter between the two legs of each pole section 6A to 6D. Since the eccentricity of the magnetic part 7a and the conductive part 7b is shifted by 180 degrees, the polar parts 6A~
In 6D, when the magnetic material portion 7a has penetrated the most, the conductive material portion 7b has penetrated at all, and on the other hand, when the conductive material portion 7b has penetrated the most, the magnetic material portion 7a has not penetrated at all. Eddy currents flow most easily in the state where the conductor portion 7b penetrates the deepest between the two legs of the pole portions 6A to 6D (for example, the state where it penetrates into 60 in FIGS. 7 and 8). In this state, the magnetic material portion 7a completely penetrates into the leg portion of the pole portion 6C, and the magnetic resistance increases. Therefore, similar to the embodiments described above, the magnetic resistance is increased synergistically. Note that the conductor portion 7b does not need to be entirely made of a conductor, and may be used to form an eddy current path.
The conductor may be used partially (for example in a ring shape along the circumference of the disk) to obtain the desired result.

In the embodiment shown in FIGS. 9 and 10, the pole portions 8A to 8D corresponding to each phase A to D of the stator portion 8 are composed of independent U-shaped magnetic cores for one phase. A primary winding W and a secondary winding W2 are wound around each pole portion 8A to 8D, respectively. The rotor part 9 inserted into the space surrounded by the ends of the stator pole parts 8A to 8D has a cylindrical shape as a whole, and magnetic parts 9a and conductive parts 9b are arranged alternately in a single-thread arrangement. It is arranged in a spiral shape. The crests of the screw correspond to the magnetic portions 9a, and the troughs are provided with the conductive portions 9b. In FIG. 10, for convenience of illustration, the crests (magnetic material portions 9a) and troughs of the screw may be made of a magnetic material in a side view. The larger the opposing area between the end of each of the pole parts 8A to 8D and the magnetic part 9a of the rotor part 9, the more the magnetic resistance decreases, and the larger the opposing area between the end and the conductive part 9b, the more the magnetic resistance increases. do. Magnetic portion 9a and conductive portion 9
b are provided alternately in the form of a single thread, so the opposing area between these parts and each of the pole parts 8A to 8D changes depending on the rotational position, and the operation is similar to that of the previous embodiment, resulting in a synergistic effect. A change in magnetoresistance can be obtained.

In each of the above embodiments, the cycle of magnetic resistance change at each stator pole is one cycle per rotation, but the 11th
In the embodiment shown in the figure and FIG. 12, there are three cycles per revolution. Each pole part 10A of the stator part 10~
10D, as described above, consists of an independent U-shaped magnetic core for each phase, and each has a primary and secondary winding W.
,, W2 is wound. Stator pole part 10A-10
The rotor part 11 inserted into the space surrounded by each end of D has a cylindrical shape as a whole, and has a gear-shaped magnetic part 11a having three teeth, and a recess between each tooth is filled. 3
It consists of a piece of conductor portion 11b. Rotor part 11
Looking at the circumferential surface of , the magnetic material portions 11a and the conductive material portions 11b are arranged alternately with a width of 60 degrees, and the magnetic resistance change in each stator pole portion 10A-jOD is determined by assuming that the rotation range of 120 degrees is one cycle. arise. Therefore, three cycles of magnetoresistance change occur per revolution. In the embodiment shown in FIGS. 13 and 14, the magnetic resistance changes in two cycles per revolution in the conductive portion at the location where the magnetic resistance increases due to the recess of the magnetic portion 11a. Stator part 12
has eight pole parts 12A to 12 at intervals of 45 degrees in the circumferential direction.
D, 12A to 12D, and the same phases face each other at an interval of 180 degrees. The rotor portion 13 has an elliptical cylindrical shape as a whole, and includes an elliptical cylindrical i-conductor portion 13a and a ring-shaped conductor portion 13b wound around the longitudinal direction along the major axis of the elliptical cylinder. It is growing. Since the magnetic portion 13a has an elliptical cylindrical shape, each pole portion 12A to 12D, 12A to
At 12D, a magnetic resistance change occurs in which one rotation is one cycle. On the other hand, since the conductor portion 13b forms a short ring along the long axis of the elliptical cylinder,
In the example of FIG. 3, when 12A and 12A) correspond to the short diameter portion of the magnetic body portion 13a, the largest amount of eddy current flows depending on the magnetic flux passing through the pole portion. At the pole portion corresponding to this short diameter portion, the gap with the magnetic material portion 13a is maximum, and the magnetic resistance increases. Therefore, similarly to each of the above embodiments,
Magnetic resistance is increased synergistically.

The embodiments shown in FIGS. 15 and 16 also produce two cycles of magnetic resistance change per rotation. The stator section 14 has eight pole sections 14 each consisting of an independent magnetic core.
A to 14D and 14A to 14D are arranged at intervals of 45 degrees, and primary and secondary windings W, , W are wound around each pole. Similar to Figure 13, K, 2 facing each other at an interval of 180 degrees.
The two phases are the same phase. In the example of FIG. 13, the magnetic circuit is formed between two opposing identical phases through the rotor section 16 (for example, the magnetic circuit flows from the pole section 12A to the pole section 12A via the rotor section 16). In the example of FIG. 15, a magnetic circuit is formed such that the magnetic flux flows from one end of the same pole section through the rotor section 15 to the other end.

The rotor part 15 inserted into the space surrounded by the ends of each of the stator pole parts 14A to '14D has a cylindrical shape as a whole, and a magnetic part 15a and a conductive part 15b are arranged in a double-threaded arrangement. They are arranged alternately in a spiral pattern. The crests of the double thread screw correspond to the magnetic portions 15a, and the conductor portions 15b are provided at the troughs. In FIG. 16, for convenience of illustration,
The crests (magnetic material portions 15a) and troughs of the screw are shown in a side view, and may be composed of this body. Since it has a double-threaded screw structure, the change in magnetic resistance due to the change in the area facing the magnetic material portion 15a at the pole portion occurs two cycles per rotation. Furthermore, since the conductor portion 15b is provided in the portion where the magnetic resistance relatively increases, the magnetic resistance is increased synergistically.

In each of the above embodiments, the magnetic portion of the rotor portion is preferably made of iron or other ferromagnetic material;
The conductive part is relatively weakly magnetic or non-magnetic than the magnetic part, and is made of a relatively good conductive material (for example, copper, aluminum, brass, etc., or a good conductive material such as these and other materials). It is sufficient if it consists of a mixture of substances).

In each of the embodiments described above, it is possible to obtain an output signal according to the rotational position of the rotor section using a phase shift method. First, in the embodiments shown in Figures 1 to 1O, a change in magnetic resistance occurs in each phase A-D, with one rotation being one cycle, and the phase of this change in magnetic resistance is shifted by 90 degrees between adjacent phases. There is. Therefore, the level of the voltage induced in the secondary winding W2 of each phase A-D is determined by the rotation angle θ of the rotor section.
Depending on the A phase, cos θ, B phase, sin θ,
It can be expressed simply as -5 in θ for the phase and -5 in θ for the D phase. Primary windings Wl and B of A and C phases.

The primary windings HW and of the D phase are excited by alternating current signals whose air phases are shifted by 90 degrees (for example, the A and C phases are each excited by a sine wave signal sinωt, and the B and D phases are excited by a cosine wave signal cosωt). ). Then, for A and C relative, the output signals of the secondary winding W2 are added differentially, and B
, D relative also differentially add the outputs of the secondary windings W2, and add and synthesize the differential output signals of each village to obtain the final output signal Y. Then, the output signal Y can be substantially expressed in the following informal formula.

Y=sinωt cosθ−(−sinωt Cogθ
)+CO5ωt sinθ−(−cos ωt s
inθ) = 2 sin ωt COsθ+2 cos
Qlt sin θ== 2 sin (ωt+θ) If the coefficient indicated as “2” in the above formula is replaced with a constant determined according to various conditions, then Y=K sin (
ωt+θ) can be expressed as Here, since θ corresponds to the rotational position of the rotor, the primary AC signal sinωt (or cos
The rotational position can be detected by measuring the phase shift θ of the output signal Y with respect to ωt).

Secondary coil output composite signal Y and reference AC signal sinωt
(or cosωt) can be configured as appropriate. FIG. 17 shows an example of a circuit in which the phase shift θ is determined as a digital quantity. still,
Although not particularly shown, the reference AC signal si is calculated using an integrating circuit.
The phase shift θ can also be determined as an analog quantity by determining the time difference at a phase angle of 0 degrees between nωt and the output signal Y=1 (sin (ω is 10)).

In FIG. 17, the oscillator 62 generates a reference sine signal sin
A circuit for generating ωt and a cosine signal cosω[, and a phase difference detection circuit 67 is a circuit for measuring the phase shift θ. Clock pulse C generated from clock oscillator 66
P is counted by the counter 60. The counter 60 is, for example, modulo M (M is any integer), and its count value is given to the C input of the register. this flip 7
The pulse Pb output from the Q output of the 0 knob 64 is the flip 70
The pulse Pa output from the Q output is applied to the flip-flop 66, and the outputs of these 65 and 66 pass through the low-pass filters 38, 69 and amplifiers 40 and 41, and the cosine signal cosωt and the sine signal sinωt are generated. is applied to the primary winding W1° of each phase A-D. The M count in the counter 60 corresponds to the phase angle of 2π radians of these reference signals cosωt and sinωt. That is, the count value of the counter 602π −1 01 indicates the phase angle of −Fugian.

Combined output signal Y & amplifier 42 of secondary coils 2A to 2D
A square wave signal corresponding to the positive/negative polarity of the signal Y is outputted from the comparator 46 via the comparator 46. In response to the rise of the output signal of the controller 46, a pulse T is output from the rise detection circuit 44, and the count value of the counter 60 is loaded into the register 61 in response to this Noculus T. As a result, a digital value Dθ corresponding to the phase shift θ is taken into the register 61. In this way, it is possible to obtain data Dθ that indicates the rotational position within one rotation in absolute terms.

In the embodiments shown in FIGS. 11 to 16, rotational position data can be similarly obtained using the phase shift method.

However, in the embodiments shown in FIGS. 11 and 12, the magnetic resistance changes by 3 cycles per rotation, so the actual rotation angle θ
, the rotational position within the rotation of Y=Ksin(ωt+3θ) is specified in an absolute manner. Also,
In the embodiments shown in FIGS. 13 to 16, two cycles of magnetic resistance change occur per rotation, so they are specified neatly.

The signal processing method is not limited to the phase shift method mentioned above.
Like a normal differential transformer, the differential output of the secondary coil may be rectified to obtain an analog voltage with a level corresponding to the rotational position. In that case, the primary AC signals of each phase A-D may all be common, and the pole part may be the A, C phase or B phase.
, only one of the D phases may be used.

The conductor portion in the rotor portion may be formed by plating, thermal spraying, pattern baking, etching, or any other suitable surface treatment technique.

Further, the structures of the stator section and the rotor section are not limited to those shown in the embodiments, and various modifications can be made within the scope of the claims.

In addition, it is not necessary to provide the primary winding and the secondary winding separately, and it is not necessary to provide the primary winding and the secondary winding separately.
It may be common as shown in No.-39507.

〔Effect of the invention〕

As described above, according to the present invention, due to the synergistic effect of the magnetic resistance change due to the displacement of the magnetic body part and the isometric magnetic resistance change according to the eddy current loss due to the displacement of the conductive body part, the secondary output voltage with respect to the displacement is The level change range can be increased, and rotational position detection can be performed with high precision.

[Brief explanation of drawings]

FIG. 1 is a radial cross-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 same embodiment, and FIG. A graph illustrating the relationship between the next output voltage level and the rotational position, FIG. 4 is a side view showing a modification of the rotor section in the same embodiment, and FIG. 5 is a schematic front view showing another embodiment of the present invention.
6 is a sectional view taken along line VI-VI in FIG. 5, FIG. 7 is a schematic front view showing still another embodiment of the invention, and FIG. 8 is a sectional view taken along line VIII-VIII in FIG. 7. , FIG. 9 is a radial sectional view showing another embodiment of the present invention, FIG. 10 is a sectional view taken along the line X-X in FIG. 9, and FIG. 11 is a sectional view showing still another embodiment of the invention. 12 is a side view of the rotor section shown in FIG. 11, FIG. 13 is a radial sectional view showing another embodiment of the present invention, and FIG. 14 is a side view of the rotor section shown in FIG. 13. FIG. 15 is a radial cross-sectional view showing still another embodiment of the invention, il! 16 Figure C 15th m
(D, V-VIW1 cross-sectional view, FIG. 17 shows an example of a circuit for operating the rotational position detection device of the present invention by a phase shift method and measuring the amount of electrical phase shift according to the rotational position. 1. 4, 6, 8, 10, 12, 14... stator section,
1A~ID, 4A~4D, 6A~6D, 8A~
8D, IOA~IOD, 12A~12D, 14A~14
D... Stator pole portion corresponding to A-D phase, Wl...
・Primary winding, W2...Secondary winding, 2. b, 7,9゜1
1, 16, 1500. Rotor part, 2a, 5a, 7a
. 9a, 11. a, 13a, 15a...magnetic material part, 2
b, 5b, 7b, 9b, 11b, 16b, 15b...
Conductor part, 3...rotating shaft.

Claims (1)

[Claims] 1. A stator section which is excited by a primary alternating current signal and is provided with a winding means for taking out a secondary output; a rotor portion, the rotor portion comprising: a magnetic material portion having a shape that changes the magnetic resistance of the magnetic circuit passing through the winding means in accordance with relative rotational displacement with respect to the stator portion; It is provided so as to form an eddy current path for the magnetic flux at a location where the magnetic resistance is relatively increased, and is relatively weakly magnetic or non-magnetic than the magnetic material portion, and is made of a relatively good conductor. 1. A rotational position detection device comprising: a conductor portion consisting of; 2. The winding means includes a plurality of primary windings and a secondary winding, and excites each primary winding using a plurality of phase-shifted primary AC signals, thereby 2. The rotational position detection device according to claim 1, wherein a signal obtained by shifting the phase of a secondary alternating current signal according to the rotational position of the rotor portion is obtained on the side of the secondary winding.