JP2010035265A - Temperature-measuring device for rotor of electric motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a temperature-measuring device for rotor of motor, wherein accurate measurement of the temperature of a rotor can be estimated, using a simple configuration and estimate the temperature of a permanent magnet. <P>SOLUTION: The temperature measuring device is provided with: a transparent ring 18, that is formed into a cylindrical shape, fixed on an end face 14a of a rotor 14 in tight contact, transmits light, and is varied in refraction index according to temperature change; a light-emitting unit 19 that projects laser light 1 so that it is orthogonal to the direction of the axis of the transparent ring 18 and is incident on the outer circumferential surface 18a of the transparent ring 18, at a predetermined incident angle θi<SB>1</SB>; a light-receiving unit 20 that is so disposed as to receive the laser light 1 passed through the transparent ring 18 and outputs different electrical signals, according to the position where the laser light 1 enters; and an arithmetic processing unit 23 that determines the temperature of the rotor 14, based on an electrical signal output from the light-receiving unit 20. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a rotor temperature measuring device for an electric motor.

  In an electric motor having a structure in which a permanent magnet is embedded in the rotor, when the temperature of the permanent magnet embedded in the rotor rises as the motor is operated and the temperature of the permanent magnet exceeds a certain temperature, the magnetic force of the permanent magnet is increased. Demagnetized. Once a permanent magnet is demagnetized, its performance drops significantly. Therefore, the temperature information of the permanent magnet is always monitored for the motor in operation, and the temperature of the permanent magnet is adjusted to the temperature at which the magnetic force is demagnetized. Before reaching the temperature, it is necessary to adjust the temperature of the permanent magnet by limiting the current in advance.

  By the way, it is difficult to directly measure the temperature of the permanent magnet embedded in the rotor, which is a rotating body, using a wired sensor. Therefore, in the conventional electric motor, for example, the temperature of the stator coil is measured, and the temperature of the rotor is estimated without directly measuring the rotor temperature, such as estimating the temperature of the permanent magnet based on the temperature value. It was broken. The temperature of the stator coil is determined, for example, by fixing a thermistor to the coil.

  However, limiting the current to adjust the temperature of the permanent magnet may lead to a reduction in the performance and efficiency of the motor. In order to suppress such a decrease in the performance and efficiency of the electric motor, it is necessary to measure the temperature of the permanent magnet with high accuracy and minimize the current limit. When measuring the temperature and estimating the temperature of the permanent magnet based on the temperature of this coil, it has been difficult to obtain an accurate temperature of the permanent magnet.

  Therefore, conventionally, there is a technique for measuring the temperature of the rotor by attaching a thermocouple inside the rotor, connecting a light emitter to the thermocouple, and detecting the brightness of the light emitter in a contactless manner in a measurement circuit ( For example, see Patent Document 1 below).

  Further, the rotor body is fixed with two coils and a thermistor disposed between the two coils, and the current induced in one coil is supplied to the other coil via the thermistor, and the other coil Some of them measure the temperature of the rotor by detecting the generated magnetic field in a non-contact manner with a sensor coil fixed to the stator shaft (for example, see Patent Document 2 below).

JP-A-10-327561 JP 2002-39088 A

  However, in the above-described Patent Document 1, it is necessary to attach a thermocouple inside the rotor, so that the assembly work is considered to be complicated, and the position where the light emitter can be installed is the rotor. There is a problem that the convenience is not sufficient because it is only on the anti-load side.

  In addition, since the configuration described in Patent Document 2 described above is a configuration in which a coil unit composed of a plurality of members is fixed to the rotor, there is a problem that the configuration of the device becomes complicated, and further, if the rotor does not rotate. Since the temperature cannot be detected, the convenience is not sufficient, and it is necessary to correct the rotation speed, so that there is a problem that the temperature detection operation may be complicated.

  Accordingly, an object of the present invention is to provide a rotor temperature measuring device for an electric motor capable of measuring the temperature of the rotor with high accuracy and estimating the temperature of the permanent magnet with a simple configuration.

  A rotor temperature measuring device for an electric motor according to a first invention for solving the above-mentioned problem is a device for measuring the temperature of the rotor of the electric motor, and is formed in a cylindrical shape and closely fixed to an end surface of the rotor, A translucent member that transmits light and whose refractive index changes according to a temperature change, and is incident on the outer peripheral surface of the translucent member at a predetermined incident angle so as to be orthogonal to the axial direction of the translucent member. Light emitting means for emitting laser light, light receiving means arranged to receive the laser light transmitted through the light transmissive member, and outputting different electrical signals depending on the position where the laser light is incident, and the light receiving means Arithmetic processing means for obtaining the temperature of the rotor based on an electrical signal output from the motor.

  According to a second aspect of the present invention, there is provided the rotor temperature measuring apparatus for an electric motor according to the first aspect, wherein the light receiving means includes a mask member in which a hole having the same diameter as the diameter of the laser beam is formed. The translucent member is arranged so that the center of the hole and the optical axis of the laser beam coincide with each other at a predetermined temperature set in advance.

  According to a third aspect of the present invention, in the first or second aspect of the invention, the light emitting means and the light receiving means are arranged so that the laser light is incident on the light receiving means after being refracted twice. The mutual position is set.

  According to a fourth aspect of the present invention, there is provided the electric motor rotor temperature measuring apparatus according to the first or second aspect, wherein the light emitting means and the light receiving means are configured so that the laser light undergoes refraction twice and reflection once by the shaft. The mutual positions are set so as to be incident on the light receiving means.

  According to the above-described rotor temperature measuring device for an electric motor according to the present invention, the temperature of the rotor is estimated based on the change in the temperature of the translucent member that is in direct contact with the rotor, and the permanent magnet is detected based on the obtained result. Since the temperature can be estimated, the temperatures of the rotor and the permanent magnet can be estimated with high accuracy with a simple configuration.

  The light emitting means and the light receiving means can be installed on either the load side or the anti-load side, and can detect the temperature even when the rotor is stationary, and Since there is no need to consider the rotational speed of the rotor, etc., this leads to improved convenience.

  Further, the light receiving means is provided with a mask member in which a hole having the same diameter as that of the laser beam is formed, and the mask member is placed at the center of the hole and the laser beam at a predetermined temperature set in advance by the translucent member. If the optical axes are aligned with each other, a change in the position of the laser light transmitted through the translucent member can be detected with high accuracy, and the temperature of the rotor can be estimated with high accuracy.

  Embodiments of the present invention will be described in detail in the following examples.

  The first embodiment of the present invention will be described in detail with reference to FIGS. 1 is a schematic sectional view showing the structure of a rotor temperature measuring device for an electric motor according to the present embodiment, FIG. 2 is a sectional view taken along the line AA in FIG. 1, and FIG. 3 is an optical path of light transmitted through the transparent ring of the present embodiment. 4 (a) to 4 (c) are enlarged views of portions D to F in FIG. 3, FIG. 5 is a front view of the mask, and FIGS. 6 (a) and 6 (b) are books. FIG. 7 is an explanatory view showing an example of laser light incident on the light receiving portion mask in another example of the present embodiment, and FIG. 7 is a front view of a light emitting portion mask and a light receiving portion mask according to another example of the embodiment. In addition, the one-dot chain line in a figure shows the straight line (normal line) orthogonal to the circumferential direction with respect to the position where the laser beam of a transparent ring surface enters / exits.

  As shown in FIGS. 1 and 2, a motor 1 to which a rotor temperature measuring device for an electric motor according to this embodiment is applied includes a shaft 13 that is rotatably supported by a motor frame 11 via a bearing 12, and a permanent inside. A stator 14 having a stator coil 17 embedded with a magnet 16 and fixedly disposed in the hollow portion of the motor frame 11 so as to have a predetermined gap between the rotor 14 and the rotor 14 in the circumferential direction. It has.

  Further, in the present embodiment, a transparent ring 18 as a translucent member is provided on one end surface 14a of the rotor 14. The transparent ring 18 is made of a light transmitting member, is formed in a cylindrical shape, is tightly fixed to the end portion 14 a of the rotor 14, and is configured to rotate integrally with the shaft 13 and the rotor 14. A light emitting unit 19 as a light emitting unit and a light receiving unit 20 as a light receiving unit are disposed in the hollow portion of the motor frame 11 and at a position facing the outer peripheral surface 18 a of the transparent ring 18.

The light emitting section 19 is a means for emitting the laser beam 1. In this embodiment, the laser beam 1 is predetermined on the outer peripheral surface 18 a of the transparent ring so that the optical axis of the laser beam 1 is orthogonal to the axial direction of the shaft 13. It is set to that position so that it is incident at an incident angle theta _i1 of. The incident angle θ _i1 is an angle at which the laser beam 1 enters the light receiving unit 20 after being refracted twice as shown in FIG. Due to the double refraction, the laser beam 1 incident on the transparent ring 18 travels inside the transparent ring 18 at a refraction angle θ _n1 and is emitted to the outside of the transparent ring 18 at an emission angle θ _o1 .

  In addition, the light receiving unit 20 includes a light receiving unit main body 21 and a mask 22 as a mask member. The light receiving unit main body 21 is a unit that receives the laser light (transmitted light) 1 emitted from the light emitting unit 19 and transmitted through the transparent ring 18 and outputs an electrical signal corresponding to the amount of received light. The position of the light receiving unit main body 21 is set so that the laser light 1 refracted in the A part and the B part shown in FIG. 2 can be received.

  On the other hand, the mask 22 is made of a light shielding member that does not transmit light, and is provided so as to cover the light receiving surface 21 a of the light receiving unit main body 21. As shown in FIG. 5, a pinhole 22a having a diameter substantially the same as the diameter of the laser beam 1 is formed in the mask 22, and the mask 22 has, for example, a predetermined temperature Ta at which the temperature of the transparent ring 18 is set in advance. At this time, the position is set so that the laser beam 1 passes through the center of the pinhole 22a. In the present embodiment, the predetermined temperature Ta may be set according to the environment in which the electric motor is used.

  And the electric signal output from the light-receiving-part main body 21 is input into the arithmetic processing part 23 as an arithmetic processing means. The arithmetic processing unit 23 calculates the temperature of the transparent ring 18 based on the output value of the electrical signal output from the light receiving unit main body 21, and further calculates the temperature of the rotor 14 based on the calculated temperature of the transparent ring 18. This is a means for estimating the temperature of the permanent magnet 16 from the obtained temperature of the rotor 14.

  In this embodiment, as a method for obtaining the temperature of the rotor 14, for example, a relationship between the temperature of the transparent ring 18 and the temperature of the rotor 14 is acquired in advance as a reference value, and the reference value is used to determine the rotor 14. A method such as obtaining the temperature can be considered. In addition, since the permanent magnet 16 is embedded in the rotor 14 and firmly adhered to the rotor 14 with an adhesive, the temperature of the permanent magnet 16 is estimated to be substantially the same as the temperature of the permanent magnet 16 and the temperature of the rotor 14. I do.

  Hereinafter, a rotor temperature measuring method by the rotor temperature measuring apparatus for an electric motor according to the present embodiment will be described with reference to FIGS. 3 to 5.

As shown in FIGS. 3 and 4, for example, when the temperature of the transparent ring 18 is the above-described predetermined temperature Ta (for example, 25 ° C.), the laser beam emitted from the light emitting unit 19 and incident on the transparent ring 18 at the incident angle θ _i1. The light 1 passes through the transparent ring 18 at the refraction angle θ _n1a , is emitted from the transparent ring 18 at the emission angle θ _o1a , and enters the light receiving unit main body 21 through the mask 22 as indicated by the solid line in the figure. .

  Here, as described above, the pinhole 22a formed in the mask 22 has its position set so that the center and the optical axis of the laser beam 1 coincide when the temperature of the transparent ring 18 is Ta. The laser beam 1a passes through almost 100% of the pinhole 22a and is converted into an electric signal in the light receiving unit main body 21.

On the other hand, when the temperature of the transparent ring 18 is Tb (≠ Ta, for example, 75 ° C.), the refractive index n (= sin (incident angle) / sin (refractive angle)) of the transparent ring 18 depends on the temperature of the transparent ring 18. Therefore, the laser light 1 emitted from the light emitting unit 19 and incident on the transparent ring 18 at an incident angle θ _i1 is refracted as indicated by a two-dot chain line in the figure, unlike when the temperature of the transparent ring 18 is Ta. through the transparent ring 18 at the angular theta _n1b, it is emitted from the transparent rings 18 at the exit angle _θ o1b. Therefore, the optical axis of the laser beam 1b is shifted by Δd1 with respect to the center of the pinhole 22a, and a part of the laser beam 1b is shielded by the mask 22 as shown in FIG. 5, and the oblique line of the laser beam 1b in FIG. Only the marked part passes through the mask 22.

  As a result, the amount of light received by the light receiving unit main body 21 decreases as compared with the case where the temperature of the transparent ring 18 is Ta, and the electric signal input to the arithmetic processing unit 23 changes. The arithmetic processing unit 23 compares the input electrical signal with a previously obtained reference value to obtain the temperature of the transparent ring 18 and estimates the temperature of the rotor 14 and further the permanent magnet 16 from the temperature of the transparent ring 18.

  As described above, in this embodiment, the refractive index of the transparent ring 18 is changed with the temperature change of the transparent ring 18 and based on the change in the position where the light transmitted through the transparent ring 18 is incident. The temperature of the transparent ring 18 is obtained, and thereby the temperature of the rotor 14 and the temperature of the permanent magnet 16 are estimated.

  According to the above-described rotor temperature measuring device for an electric motor according to this embodiment, the temperature of the rotor 14 can be estimated by sensing using light, and therefore the temperature of the rotor 14 can be estimated with high accuracy. Further, since the temperature of the rotor 14 is estimated based on the temperature of the transparent ring 18 that is in direct contact with the rotor 14, and the temperature of the permanent magnet is estimated based on the estimated temperature of the rotor 14, high accuracy with a simple configuration. In addition, the temperature of the permanent magnet 16 can be estimated, and the performance and efficiency of the motor 1 can be improved.

  In the above-described embodiment, the predetermined temperature Ta has been described as 25 ° C., but the present invention is not limited to this. For example, various changes such as setting to a temperature that is considered to be the lowest in an environment where the electric motor is used are performed. Is possible.

  In the present embodiment, an example in which a circular pinhole 22a is provided in the mask 22 constituting the light receiving unit 20 has been shown. However, as shown in FIG. 6, for example, a position facing the laser light emitting surface of the light emitting unit 19 6A is provided with a light emitting portion mask 24 having a rectangular hole 24a as shown in FIG. 6A, while the light receiving portion 20 has a triangular shape as shown in FIG. 6B as a mask member instead of the mask 22 described above. Various modifications can be made without departing from the gist of the present invention, such as providing the light receiving portion mask 25 having the holes 25a.

  In the case of the above configuration, for example, the temperature of the transparent ring 18 changes from a low temperature to a high temperature, whereas the laser beam is set to move from the bottom side of the triangular hole 25a of the light receiving portion mask 25 to the apex side. Then, as shown in FIG. 7, the laser beam 1a is irradiated at a position indicated by a solid line at a low temperature, and the laser beam 1b is irradiated at a position indicated by a broken line at a high temperature, and each is hatched. When the portion passes through the hole 25a, the amount of light received incident on the light receiving unit main body 21 changes.

  As described above, the amount of light received measured at the light receiving unit main body 21 changes with the temperature change of the transparent ring 18, so that the obtained light reception amount is converted into an electric signal, and the arithmetic processing unit 23 determines from the light receiving unit main body 21. The temperature of the transparent ring 18 can be obtained by comparing the input electric signal with a reference value obtained in advance, and the temperature of the rotor 14 and further the permanent magnet 16 is estimated from the temperature of the transparent ring 18. Can do.

  The second embodiment of the present invention will be described in detail with reference to FIGS. 8 is a cross-sectional view of the electric motor of the present embodiment, FIG. 9 is an explanatory diagram showing changes in the optical path of light transmitted through the transparent ring of the present embodiment, and FIGS. It is an enlarged view of the L section. The present embodiment is an example in which the positions of the light emitting unit 19 and the light receiving unit 20 are changed in the first embodiment. Hereinafter, the same members as those shown in FIGS. A duplicate description is omitted.

As shown in FIG. 8, in the present embodiment, the light emitting unit 19 is configured so that the optical axis of the laser beam 1 is orthogonal to the axial direction of the shaft 13 and the laser beam 1 is incident on the outer peripheral surface 18a of the transparent ring at a predetermined incident angle θ _i2. The position is set so as to be incident. The incident angle θ _i2 is an angle at which the laser beam 1 enters the light receiving unit 20 after being refracted twice and reflected once as shown in FIG. The laser light 1 incident on the transparent ring 18 travels through the inside of the transparent ring 18 at a refraction angle θ _n2 and is emitted to the outside of the transparent ring 18 at an emission angle θ _o2 due to twice refraction and one reflection.

  In addition, the position of the light receiving unit main body 21 is set so that the laser beam 1 refracted or reflected by the F unit, the G unit, and the H unit shown in FIG. 8 can be received. Further, the mask 22 is arranged so that the optical axis of the laser beam 1 coincides with the center of the pinhole 22a when the transparent ring 18 is at a predetermined temperature Ta, as in the first embodiment.

  A rotor temperature measuring method using the rotor temperature measuring apparatus for an electric motor according to this embodiment will be described with reference to FIGS. 9 and 10.

As shown in FIGS. 9 and 10, for example, when the temperature of the transparent ring 18 Ta (for example 25 ° C.), the laser beam 1 that is incident on the transparent ring 18 is emitted incident angle theta _i2 from the light emitting unit 19 has a refractive The light passes through the transparent ring 18 at the angle θ _n2a , is reflected by the rotor 14, is then emitted from the transparent ring 18 at the emission angle θ _o2a , and is incident on the light receiving unit main body 21 through the mask 22. Here, as described above, the pinhole 22a formed in the mask 22 has its position set so that the center and the optical axis of the laser beam 1 coincide when the temperature of the transparent ring 18 is Ta. The laser beam 1a passes through almost 100% of the pinhole 22a and is converted into an electric signal in the light receiving unit main body 21.

On the other hand, the temperature Tb (≠ Ta, for example, 75 ° C.) of the transparent ring 18 when, for the refractive index n of the transparent ring 18 that varies depending on the temperature of the transparent rings 18, at an incident angle theta _i2 emitted from the light emitting portion Unlike the case where the temperature of the transparent ring 18 is Ta, the laser beam 1 incident on the transparent ring 18 is transmitted through the transparent ring 18 at a refraction angle θ _n2b , reflected by the rotor 14, and then at an emission angle θ _o2b . The light is emitted from the transparent ring 18.

  Therefore, the optical axis of the laser beam 1b is shifted by Δd2 with respect to the center of the pinhole 22a, and a part of the laser beam 1b is shielded by the mask 22. As a result, the amount of light received by the light receiving unit main body 21 decreases as compared with the case where the temperature of the transparent ring 18 is Ta, and the electric signal input to the arithmetic processing unit 23 changes. The arithmetic processing unit 23 compares the input electrical signal with a previously obtained reference value to obtain the temperature of the transparent ring 18 and estimates the temperature of the rotor 14 and further the permanent magnet 16 from the temperature of the transparent ring 18.

  Thus, according to the rotor temperature measuring device for an electric motor according to the present embodiment, the temperature of the rotor 14 can be estimated by sensing using light, and therefore the temperature of the rotor 14 can be estimated with high accuracy. . Further, since the temperature of the rotor 14 is estimated based on the temperature of the transparent ring 18 that is in direct contact with the rotor 14, and the temperature of the permanent magnet is estimated based on the estimated temperature of the rotor 14, high accuracy with a simple configuration. In addition, the temperature of the permanent magnet 16 can be estimated, and the performance and efficiency of the motor 1 can be improved.

  Note that the shape of the pinhole is not limited to a circle, and may be any shape that changes the amount of received light incident on the light receiving unit main body 20 according to the position where the laser beam 1 is incident, and the refractive index is derived. Needless to say, changes can be made to the extent possible.

  The present invention is applicable to a rotor temperature measuring device for an electric motor.

It is a schematic sectional drawing of the rotor temperature measuring apparatus of the electric motor which concerns on Example 1 of this invention. It is XX arrow sectional drawing of FIG. It is explanatory drawing which shows the example of the change of the optical path in the rotor temperature measuring apparatus of the electric motor which concerns on Example 1 of this invention. 4A is an enlarged view of a C portion shown in FIG. 3, FIG. 4B is an enlarged view of a D portion shown in FIG. 3, and FIG. 4C is an enlarged view of an E portion shown in FIG. It is a front view which shows the example of the mask which concerns on Example 1 of this invention. FIG. 6A is a front view showing an example of a light-emitting portion mask according to Embodiment 1 of the present invention, and FIG. 6B is a front view showing another example of a light-receiving portion mask according to Embodiment 1 of the present invention. FIG. It is explanatory drawing which shows the example of the laser beam which injects into the mask for light-receiving parts shown in FIG. It is XX arrow sectional drawing of FIG. 1 of the rotor temperature measuring apparatus of the electric motor which concerns on Example 2 of this invention. It is explanatory drawing which shows the example of the change of the optical path in the rotor temperature measuring apparatus of the electric motor which concerns on Example 2 of this invention. 10 (a) is an enlarged view of the I part shown in FIG. 9, FIG. 10 (b) is an enlarged view of the J part shown in FIG. 9, FIG. 10 (c) is an enlarged view of the K part shown in FIG. FIG. 10 is an enlarged view of a portion L shown in FIG. 9.

Explanation of symbols

1 Laser beam (optical axis)
1a Laser light (at low temperature)
1b Laser light (at high temperature)
DESCRIPTION OF SYMBOLS 11 Motor frame 12 Bearing 13 Shaft 14 Rotor 14a Rotor end 15 Stator 16 Permanent magnet 17 Stator coil 18 Transparent ring 19 Light emitting part 20 Light receiving part 21 Light receiving part main body 22, 25 Mask 23 Arithmetic processing part

Claims (4)

A device for measuring the temperature of a rotor of an electric motor,
A light-transmitting member that is formed in a cylindrical shape and is closely fixed to the end face of the rotor, transmits light, and changes its refractive index in accordance with a temperature change;
A light emitting means for emitting laser light so as to be perpendicular to the axial direction of the light transmissive member and to be incident on the outer peripheral surface of the light transmissive member at a predetermined incident angle;
A light receiving means arranged to receive the laser light transmitted through the light transmissive member, and outputting different electrical signals depending on the position where the laser light is incident;
An apparatus for measuring a rotor temperature of an electric motor, comprising: arithmetic processing means for obtaining a temperature of the rotor based on an electric signal output from the light receiving means.   The light receiving means includes a mask member in which a hole having the same diameter as the diameter of the laser beam is formed, and the mask member has a center of the hole when the light transmitting member has a predetermined temperature set in advance. The rotor temperature measuring device for an electric motor according to claim 1, wherein the rotor temperature measuring device is arranged so as to coincide with an optical axis of the laser beam.   The rotor of an electric motor according to claim 1 or 2, wherein the light emitting means and the light receiving means are mutually positioned so that the laser light enters the light receiving means after being refracted twice. Temperature measuring device.   2. The position of the light emitting means and the light receiving means is set so that the laser light is incident on the light receiving means after being refracted twice and reflected once by the shaft. Or the rotor temperature measuring apparatus of the electric motor of 3.

Images