JPH0716104U - Magnetic resolver - Google Patents

Abstract

(57) [Abstract] [Purpose] To detect the rotational position with high resolution by increasing the amplitude change of the induced voltage in a magnetic resolver. [Structure] Conductive portion 1 which is a non-magnetic material and a good conductor
3, 14 are arranged so as to surround the pole teeth 50, 52 of the stator part 1.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a magnetic resolver used for detecting the position of a servomotor of a machine tool.

[0002]

[Prior art]

 5 is a diagram showing an example of a conventional magnetic resolver, FIG. 6 is a sectional view taken along the line CC ′ of FIG. 5, and FIG. 3 is a block diagram showing an example of an electric circuit of the magnetic resolver of FIG. Yes, and FIG. 4 is a timing chart thereof. In FIGS. 3 and 4, the timing generator 4 generates a clock signal CLK and a hold signal HD which are two synchronized signals. The excitation signal generator 5 generates an excitation signal e which is a rectangular wave signal synchronized with the clock signal CLK. The excitation signal e may be a signal corresponding to a trigonometric function. In FIG. 5, the lids 60 and 61 sandwich and fix the stator portion 1, and support the rotary shaft 3 through bearings 70 and 71. In FIG. 6, the stator portion 1 has four pole teeth 50 to 53 made of a magnetic material such as silicon steel plate corresponding to the four phases E to H arranged at intervals of 90 degrees along the circumferential direction. One. A primary winding 30-33 and a secondary winding 40-43 are wound around each pole tooth 50-53. The ends of the pole teeth 50 to 53 are directed inward, and the rotor portion 2 is arranged in the space surrounded by the ends via a gap. The rotor portion 2 is composed of a cylindrical magnetic body portion 2 a that is eccentric with respect to the rotating shaft 3. Due to the eccentric shape of the magnetic body portion 2a, when the rotor portion 2 rotates, the air gap between the cylindrical side surface of the magnetic body portion 2a and the end portions of the pole teeth 50 to 53 changes according to the rotation angle θ. The change in the gap causes a change in the magnetic resistance corresponding to a trigonometric function for one cycle per one rotation of the rotor portion 2 in each of the phases E to H. As a result, the amplitude of the induced voltage in the secondary windings 40 to 43 changes. For example, in the E phase of FIG. 6, the magnetic resistance becomes the minimum when the air gap between the pole tooth 50 and the magnetic body portion 2a becomes the minimum, and the induced voltage VE of the secondary winding 40 at the pole tooth 50 becomes small. Has the maximum amplitude. Then, as the rotor portion 2 rotates, the air gap widens, and the magnetic resistance increases accordingly, so that the amplitude of the induced voltage VE of the secondary winding 40 decreases as shown by the broken line in FIG. In this way, a change in the induced voltage corresponding to a trigonometric function for one cycle per rotation of the rotor portion 2 is introduced in the E phase.

The position detection signals a and b are amplified by the amplifiers 6 and 7 and input to the sample and hold circuits 8 and 9. The sample and hold circuits 8 and 9 hold the input signal when the hold signal HD is at "H" level, and sample when the hold signal HD is at "L" level. The A / D converters 10 and 11 convert the analog signals output from the sample and hold circuits 8 and 9 into digital signals A and B at the rising edge of the hold signal. The interpolation circuit 12 calculates and outputs the target angle θ by taking the arc tangent of the result of dividing the digital signals A and B.

[0004]

[Problems to be solved by the device]

 In recent years, miniaturization of servo motors has progressed, and there has been a demand for a thinner magnetic resolver built in the motor (downsizing in the axial direction). When the magnetic resolver is made thin, the magnetic resistance in the air gap between the cylindrical side surface of the rotor part 2 and the ends of the pole teeth 50 to 53 increases, and the magnetic flux that does not pass through the rotor part 2, that is, FIG. And leakage fluxes i and j as shown in FIG. 6 increase. Therefore, there is a problem in that the change in the amplitude of the induced voltage in the secondary windings 40 to 43 is small with respect to the magnetic flux generated by the excitation signal e, and the position detection resolution is reduced due to the noise component. The present invention has been made to solve such a problem, and an object thereof is to realize a small magnetic resolver capable of detecting a rotational position with high resolution by increasing a change in amplitude of an induced voltage. .

[0005]

[Means for Solving the Problems]

 The present invention relates to a magnetic resolver used for position detection of a servomotor of a machine tool, and the above object of the present invention is to provide a secondary winding for extracting a primary winding and a secondary output excited by an AC signal. A stator part having pole teeth made of a magnetic material with a winding, and a stator part arranged so as to be relatively rotatable and displaceable relative to the stator part. In a magnetic resolver having a rotor portion having a magnetic body portion shaped to change the magnetic resistance of a magnetic circuit passing through a winding, a conductive portion that is a non-magnetic body and a good conductor is It is achieved by arranging so as to surround the pole teeth of.

[0006]

[Action]

 In the present invention, an eddy current is generated in the conductive part to make it difficult for the magnetic flux to enter and the leakage magnetic flux to be reduced, so that the change in the amplitude of the induced voltage becomes large, resulting in a small noise ratio and high resolution. The rotational position can be detected with.

[0007]

【Example】

 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a view showing an example of the magnetic resolver of the present invention, and FIG. 2 is a sectional view taken along the line D-D 'of FIG. 1 and 2 that are the same as those in FIGS. 5 and 6 are denoted by the same reference numerals. In FIG. 1, the conductive portions 13 and 14 are made of a metal such as aluminum, and are arranged close to each other so as to surround the pole teeth 50 of the stator portion 1. In such a magnetic resolver, magnetic flux easily flows from the pole teeth 50 toward the rotor portion 2 as shown in FIGS. 1 and 2, but from the primary winding 30 or the pole teeth 50 to the conductive portions 13 and 14. It is difficult for the magnetic flux to flow in. This will be described in more detail. When the leakage magnetic fluxes i and j try to pass from the primary winding 30 and the pole teeth 50 toward the conductive portions 13 and 14, eddy currents are generated in the conductive portions 13 and 14 through which the leakage magnetic fluxes i and j pass. Occurs. Due to the eddy current, magnetic fluxes m and n are generated in a direction that cancels the leakage magnetic fluxes i and j. As a result, the leakage magnetic fluxes i, j and the magnetic fluxes m, n cancel each other, so that it becomes difficult for the magnetic flux to flow from the primary winding 30 or the pole teeth 50 toward the conductive portions 13, 14. Therefore, most of the magnetic flux will flow into the rotor, and the leakage flux will be small. When the leakage magnetic flux decreases, the magnetic flux passing through the secondary winding in the state where the air gap between the pole tooth 50 and the magnetic body portion 2a is minimized and the air gap when the rotor portion 2 is rotated The difference in the magnetic flux passing through the secondary winding increases, and the change in the amplitude of the induced voltage increases.

[0008]

[Effect of device]

 As described above, according to the magnetic resolver of the present invention, an eddy current is generated in the conductive portion to make it difficult for the magnetic flux to enter and the leakage magnetic flux to be reduced, resulting in a large change in the amplitude of the induced voltage. The ratio becomes smaller, and a small magnetic resolver that detects the rotational position with high resolution can be realized, and the applicable range can be expanded. Although the magnetic resolver that detects the rotational position has been described here, the same effect can be obtained for the magnetic resolver that detects the linear position by disposing the conductive portion so as to surround the pole teeth of the stator. Needless to say.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of a magnetic resolver of the present invention.

FIG. 2 is a diagram showing a D-D ′ cross section of FIG. 1;

FIG. 3 is a block diagram showing an example of an electric circuit of the present invention and a conventional magnetic resolver.

FIG. 4 is a timing chart of FIG.

FIG. 5 is a diagram showing an example of a conventional magnetic resolver.

6 is a diagram showing a cross section taken along the line C-C ′ of FIG. 5;

[Explanation of symbols]

 1 Stator part 2 Rotor part 3 Rotating shaft 4 Timing generator 5 Excitation signal generator 6, 7 Amplifier 8, 9 Sample and hold circuit 10, 11 A / D converter 12 Interpolation circuit 13, 14 Conductive part 30- 33 primary winding 40-43 secondary winding 50-53 pole teeth 60, 61 lid 70, 71 bearing

Claims (1)

[Scope of utility model registration request] 1. A stator portion having pole teeth made of a magnetic material, which has a primary winding excited by an AC signal and a secondary winding for taking out a secondary output, and a stator portion relative to the stator portion. A magnetic resolver having a rotor portion that is arranged so as to be rotationally displaceable and that has a magnetic body portion having a shape that changes the magnetic resistance of a magnetic circuit that passes through the secondary winding in accordance with relative rotational displacement with respect to the stator portion. A magnetic resolver characterized in that a conductive portion which is a non-magnetic material and is a good conductor is arranged so as to surround the pole teeth of the stator portion.