JP2019184506A - Device and method for measuring variation in torque of motor - Google Patents

Abstract

To provide a device and a method for precisely measuring variations in the torque such as a wow flutter, a jitter, and a cogging torque of a rotational electric motor.SOLUTION: A variation measurement device includes: a sample motor (1); a torque detector (4); an energy absorption generator (2) connected to the rotational shaft of the sample motor by the torque detector, the energy absorption generator operating as a driving motor until the number of rotation becomes a set number and thereafter operating as a generation brake; and a fly wheel (3) between the generator and the torque detector, the fly wheel having a larger moment of inertia than the moment of inertia (I) of the sample motor.SELECTED DRAWING: Figure 1

Description

The present invention relates to a torque fluctuation measuring apparatus and measuring method for a rotating motor (motor), and more particularly to a torque fluctuation measuring apparatus and measuring method capable of accurately measuring torque fluctuation due to wow flutter, jitter, cogging and the like of a motor under measurement.
Rotating motors are widely used in close proximity, but rotational stability greatly affects performance (vibration, noise, efficiency, etc.), so it is extremely important for product development to accurately measure torque fluctuations. It is.

2. Description of the Related Art Conventionally, various types of torque characteristics testing apparatuses and measuring methods for rotary motors are known (see Patent Documents 1 to 3). The outline and problems of the conventional apparatus and method will be described below with reference to the contents described in these patent documents.
Conventionally, as a technique for giving a load torque in a pseudo manner in a torque characteristic test of a rotary motor, it is common to provide a brake on the power transmission shaft of the rotary motor to be measured. Examples of such a brake include a friction brake that obtains a braking force by a frictional force generated by a brake shoe, an electromagnetic powder brake in which magnetic powder (powder) is sealed between a driving portion and a driven portion, and Patent Document 1 The disclosed hysteresis brake for generating a hysteresis loss and applying load torque, and further, another rotating motor driven by the rotating operation of the rotating motor to be measured disclosed in Patent Document 2 and Patent Document 3, The power generation brake that gives load torque by doing the same) is known.

FIG. 7 is a conceptual diagram showing an example of a torque measuring device based on the hysteresis brake method described in FIG. In FIG. 7, the rotating shaft 13 of the object 12 to be measured fixed to the measuring table 17 is fixed to the disk 15 with a joint 14. The disk 15 rotates with the rotation of the object 12 to be measured, but generates a braking force corresponding to the current value by energizing the electromagnet 16. The measured object 12 is rotated to gradually increase the value of the current applied to the electromagnet 16, and the torque value corresponding to the torque value of the measured object 12 and the braking force are balanced and the corresponding torque value is obtained. It is a device that knows.
In the case of this type of device, the inertial force of the detectors such as the disk 15, the joint 14 and the like is relatively large, and (b) the torque that fluctuates, Torque at the time, (d) Torque at the time of reverse rotation of the rotating body including reverse rotation cannot be measured.
In the case of a hysteresis brake, as described in paragraph [0004] of Patent Document 1, when the load torque that can be applied is small with respect to the size of the device and the load torque to be applied is large, the test is performed. The overall size of the machine became large and the usability was poor, and there was a problem that residual torque was generated when excitation was turned off during low-speed rotation.

In addition, as a structure of a hysteresis brake, the following things are known as well-known in the catalog of Toyo Technica Co., Ltd., Ebara Corporation, etc., for example. This hysteresis brake has a configuration in which a cylindrical iron rotor and a stator having a tooth-shaped magnetic pole excited by a coil are combined in a non-contact manner. Hereinafter, such a hysteresis brake is referred to as a “cylindrical hysteresis brake” for convenience of explanation.
Here, when the magnetic pole is not excited, the rotor rotates freely supported by the ball bearing. When a current is supplied to the coil to excite the magnetic poles, a magnetic field is generated in a gap between the rotor and magnetic friction is generated when the rotor having a high permeability rotates. Therefore, it absorbs the rotational energy of the rotor as a loss of magnetic friction and acts as a brake. The consumption energy E (w) of the hysteresis brake is E = ωT. Here, T is torque (N · m), ω is angular velocity, and ω = (2π / 60) × n. n is the rotation speed (rpm).
The torque T can be controlled by the current flowing through the coil. Note that heat generated by consumed energy is cooled by air cooling or water cooling.

  FIG. 6 is a conceptual diagram showing an example of a torque measuring device using a power generation brake system described in FIG. The apparatus of FIG. 6 includes two motor groups, each motor group is provided with speed detecting means for detecting the respective rotation speeds, and the motor groups are connected via a torque meter. The group is a load device (generator), and the other motor group is a drive device that is a motor for driving electrical products, and the drive conditions of each of these motor groups are configured to be variable. FIG. 4 of Patent Document 3 describes an example of a graph showing the state of torque fluctuation of the drive side and load side electric motors.

  Regarding the problem of the power generation brake system, paragraph [0005] of Patent Document 1 describes as follows. That is, in the power generation brake, the electric power generated by the power generation operation is consumed as thermal energy by the electric resistance, and the braking torque is obtained to generate the load torque. In this case, the high speed rotation that generates a large amount of electric power is performed. In order to change the load torque, it is necessary to use an electric resistance that can consume a large amount of power, and it is also necessary to use a variable resistance, so that the load must be expensive. It was unsuitable for improving the test accuracy by making the torque correspond to the desired magnitude with high accuracy. "

  Eliminates the problems of the hysteresis brake system and power generation brake system as described above, and provides a pseudo-load torque generator that can apply various load torques at a high speed rotation of the rotating motor to be measured. For the purpose of “to do”, an apparatus as in Patent Document 1 has been proposed. FIG. 5 is an embodiment of the apparatus described as FIG. In the apparatus of FIG. 5, the pseudo load torque generator 1 and the measured rotary motor M are coupled to the power transmission shaft Ms of the measured rotary motor M via the drive side coupling 4. On the other hand, in the pseudo load torque generator 1, the drive side coupling 4 and one rotating shaft of the torque detector 3 are connected, and the driven side coupling 5 is connected to the other rotating shaft of the torque detector 3. The rotating shaft of the brushless DC motor 2 (power generation unit) is connected through the via.

  The rotary electric motor M to be measured is supplied with electric power from the power source P, is speed-controlled by the drive control unit Dv, and is driven at a predetermined rotational speed. Here, the brushless DC motor 2 driven by the measured rotary motor M acts as a generator, and acts as a so-called power generation brake that applies load torque to the measured rotary motor M. The load torque amount to be applied is controlled by controlling the current amount of the collector current Ic flowing between the collector C and the emitter E of the power transistor 11 provided in the power consumption unit 10 connected to the brushless DC motor 2. On the other hand, in the torque detector 3, since the brushless DC motor 2 acts as a brake on the rotating motor M to be measured during the rotation operation, the shaft connected to the driving side coupling 4 and the driven side coupling 5 are connected. Torsion occurs with the generated shaft, and the actual torque generated there is detected and output to the load torque setting unit 30.

The above-described hysteresis brake system, power generation brake system, and improved power generation brake system also have the following problems in common. When the motor to be measured is rotated, even if it is rotated at a constant speed, unevenness (unevenness) and fluctuations in rotational torque may occur in the rotation. These fluctuation phenomena are explained by terms such as wow and flutter, jitter, and cogging. However, with conventional measuring devices, it is impossible to accurately measure torque fluctuations based on the fluctuation phenomena in the motor under measurement. there were.
By the way, wow flutter (English: wowand flutter) is a change in frequency caused by, for example, unevenness in the rotating part of a recording / playback device. Jitter, which is particularly problematic in the telecommunications field, for example, is signal fluctuation in the time axis direction. Cogging is a phenomenon in which the magnetic attraction force between the armature and rotor of the motor pulsates finely depending on the rotation angle, and the rotational torque of the turntable fluctuates. Affect. If the wow and flutter are large, the sound can be heard.
In order to improve the stability and performance of rotation, it is important to accurately measure the torque fluctuation based on the fluctuation phenomenon in the rotary electric motor (motor). In particular, accurate measurement is required even at high frequencies.

JP 2016-23997 A Japanese Patent Laid-Open No. 61-111433 Japanese Patent Laid-Open No. 3-212194

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a torque fluctuation measuring apparatus capable of accurately measuring torque fluctuations due to wow flutter, jitter, cogging, etc. in the motor under measurement. And providing a measuring method.

In order to solve the above-mentioned problems, the measuring apparatus of the present invention is solved by the following. That is, a torque fluctuation measuring device for a rotary motor, which is a test motor (1) as a motor to be measured, a torque detector (4) for detecting torque by twisting of the shaft, and a rotation shaft of the test motor. Torque fluctuation measurement provided with an energy absorbing generator (2) connected to the motor via the torque detector (4) and operating as a drive motor up to a set number of revolutions and thereafter acting as a power generation brake In the apparatus, a flywheel having a larger moment of inertia between the energy absorbing generator (2) and the torque detector (4) than the moment of inertia (I ₁ ) of the motor under test (1). (3) is provided. Preferably, the inertia moment (I _f ) of the flywheel is a sufficiently large inertia moment so that the fluctuation of the angular velocity of the rotating shaft based on the rotation of the energy absorbing generator (2) can be ignored. And

As a preferred embodiment of the invention, the rotating shaft of the energy absorbing generator (2) and the rotating shaft of the flywheel (3) are connected via a vibration removing coupling (5). Is preferred.

Furthermore, the measurement method of the present invention can be solved by using the following method. That is, in the method of measuring the torque characteristics of the rotary motor using the torque fluctuation measuring apparatus as described above, the torsion spring constant (K _n ) of the rotating shaft system including the spring constant of the torque detector (4) is increased. Thus, the natural frequency f _n ≈½π × √ (K _n / I ₁ ) of the measurement system is increased, thereby enabling measurement when the measurement frequency is high.

Further, the vibration removal coupling (5) in the torque fluctuation measuring device according to the preferred embodiment is a rubber coupling having a relatively small spring constant, and the spring constant of the torque detector (4) is relatively large. As a matter of fact, by making the torsion spring constant (K _n ) of the rotating shaft system relatively large as a whole, the natural frequency f _n ≈½π × √ (K _n / I ₁ ) of the measurement system is increased. It is characterized by doing.

  According to the present invention, it is possible to provide a torque fluctuation measuring device and a measuring method capable of accurately measuring the torque fluctuation caused by the wow flutter, jitter, cogging, etc. in the motor under measurement. It is also possible to accurately measure the torque fluctuation not only when the measured motor rotates at a constant speed but also when the measured motor is accelerated, decelerated, and during alternating rotation in which forward rotation and reverse rotation are alternately performed. . Further, in the case of the hysteresis brake system, the influence of heat by the brake may affect the torque detector, but such a problem does not occur in the apparatus of the present invention. Further, in the measurement method of the present invention, since the spring constant of the measurement system (torsional vibration system) is large, there is an advantage that measurement can be performed with high accuracy even when the measurement frequency is high.

1 is a schematic block diagram of a measuring apparatus according to the present invention. 1 is a block diagram of a measurement system including a measurement device according to the present invention. It is a figure which shows the Example of the measuring device which concerns on this invention, Comprising: (a) is a top view, (b) is a front view, (c) is a side view. The schematic block diagram of the conventional measuring device. The conceptual diagram which shows an example of the torque measuring apparatus by the improved electric power generation brake system described in FIG. The conceptual diagram which shows an example of the torque measuring device by the power generation brake system described in FIG. 1 of patent document 3. FIG. The conceptual diagram which shows an example of the torque measuring apparatus by the hysteresis brake system described in FIG. 5 of patent document 2. FIG.

  The measuring apparatus and method of the present invention will be described in detail with reference to FIGS. First, in describing the configuration and operational effects of the present invention, the conventional system configuration and operation related thereto will be described based on the schematic block diagram of the conventional measuring apparatus in FIG.

  In the system shown in FIG. 4, the test motor 31 and the hysteresis brake 21 are connected via a torque detector 41, and this system forms one torsional vibration system. The natural frequency of such a torsional vibration system will be discussed below. The hysteresis brake 21 is described as the above-described cylindrical hysteresis brake for the sake of convenience of explanation, but the same description holds true for other types of hysteresis brakes and power generation brakes that also function as drive motors.

In the system shown in FIG. 4, when the brake is operating, the angular velocity ω need not be considered, so only the angular acceleration dω / dt is considered. Here, I ₁ is the moment of inertia of the test motor 31, I ₂ is the moment of inertia of the hysteresis brake 21, K is the torsion spring constant of the rotating shaft system including the spring constant of the torque detector 41, and the hysteresis brake coil The natural frequency of the system is examined for the case where the current flowing in the system is controlled and the case where it is not controlled.

  In general, the rotating body has characteristics with respect to angular velocity ω and angular acceleration dω / dt, but the hysteresis brake has a control function with respect to angular velocity ω, and does not have a control function with respect to angular acceleration dω / dt. Therefore, the brake connected to the rotating body controls ω, but when the shaft torque changes due to dω / dt, dω / dt cannot be suppressed unless the current flowing in the coil is controlled.

In the system shown in FIG. 4, when the current flowing through the coil is controlled, dω / dt = 0 on the axis on the hysteresis brake 21 side, so the natural frequency f ₁ of the system is f ₁ = 1 / 2π × √. (K / I ₁ ). In this case, the test motor 31 rotates at the average angular velocity ω while vibrating at the frequency of f ₁ .

Next, in the system of FIG. 4, when the current flowing through the coil is not controlled, the natural frequency f ₃ of the system is f ₃ = 1 / 2π × √ (K / I ₃ ). Here, I ₃ = 1 / {(1 / I ₁ ) + (1 / I ₂ )}.
In this case, part of dω / dt is transmitted to the hysteresis brake side, and the test motor 31 and the hysteresis brake 21 rotate at an average angular velocity ω while vibrating with a phase difference of 180 °. Therefore, in the system of FIG. 4, the fluctuation of the angular velocity of the rotating shaft based on the rotation of the hysteresis brake 21 cannot be ignored, and the torque detector has such a relationship that the hysteresis brake 21 absorbs the energy fluctuation generated by the test motor 31. 41 is measured. That is, it is impossible to accurately measure the torque fluctuation described above.

Next, the measurement apparatus and method of the present invention will be described with reference to FIG. As in FIG. 4, the system of FIG. 1 operates as a drive motor up to the test motor 1 and the rotation speed set at the start of the test, and acts as a power generation brake while controlling the rotation speed during the test. Although the absorption generator 2 is connected via the torque detector 4, the point that the flywheel 3 is provided between the energy absorption generator 2 and the torque detector 4 is the same as FIG. Is different. The inertia moment (I _f ) of the flywheel 3 has a large inertia moment compared to the inertia moments (I ₁ ) and (I ₂ ) of the motor under test 1 and the energy absorbing generator 2. The inertia moment (I _f ) of the flywheel is an inertia moment that is sufficiently large so that the fluctuation of the angular velocity of the rotating shaft based on the rotation of the energy absorbing generator (2) can be ignored. For example, the inertia moment (I _f ) of the flywheel is 2.33 × 10 ³ kg · cm ^2, which is 233 times the value of the inertia moment (I ₁ ) of the test motor 1 (for example, 10 kg · cm ² ). . When the inertia moment (I _f ) of the flywheel 3 is large, only the fluctuation of the test motor 1 is transmitted to the torque detector 4, and the above-described torque fluctuation of the test motor 1 itself can be accurately measured.

In the system of FIG. 1, when the spring constant twist of the rotating shaft system that includes a spring constant of the torque detector 4 and K _n, the natural frequency f _n of the _{system, f n ≒ 1 / 2π ×} √ (K n / I ₁ ). Accordingly, by increasing the spring constant (K _n ), the natural frequency f _n of the measurement system can be increased, thereby enabling measurement when the measurement frequency is high.

  The details of the measurement system of the present invention will be described in detail with reference to FIGS. FIG. 2 is a block diagram of a measurement system including the measurement device according to the present invention, FIG. 3 is a diagram showing an embodiment of the measurement device according to the present invention, (a) is a top view, and (b) is a front view. FIG. 3C is a side view. 1 to 3, members having the same function are denoted by the same reference numerals and redundant description is omitted.

  2 is a schematic block diagram of the measuring apparatus of the present invention shown in FIG. 1 with other members necessary for measurement added, where 1 is a test motor and 2 is a drive. Motor (energy absorbing generator), 3 is flywheel, 4 is a torque detector, 5 is a coupling for removing vibration, 6 is a controller for generator control, 7 is a rotation speed indicator, 8 is a regenerative resistor, Reference numeral 10 denotes a data logger for measuring the motor characteristics under test, a recorder, 11 a controller for rotating the motor, and 12 a computer for system control. Among the above, the members 1 and 9 to 12 are prepared by a user who performs measurement using the measurement apparatus.

An additional description relating to the present invention will be given with respect to some of the additional recording members in FIG. First, the regenerative resistor 8 will be described. When the energy absorbing generator 4 itself cannot absorb the energy generated by the test motor 1, the energy is absorbed by the external resistance, that is, the regenerative resistor 8. Recently, a method of returning power to the original power source has also been adopted.

Next, the vibration removing coupling 5 will be described. The energy absorbing generator 2 and the flywheel 4 are connected via a vibration removing coupling 5, and this vibration removing coupling 5 is a rubber having a relatively small spring constant (K _d ). Coupling is preferred. The reason will be described below.
As described above, the inertia moment of the flywheel 3 is (I _f ), the inertia moments of the test motor 1 and the energy absorbing generator 2 are (I ₁ ) and (I ₂ ), respectively, and the torque detector The rotational shaft system having the members 1 to 5 in FIG. 2 is assumed to have the torsion spring constant of the rotating shaft system including the spring constant of 4 as (K _n ) and the spring constant of the vibration removal coupling 5 as (K _d ). Consider the vibration system.
The vibration system is a two-degree-of-freedom vibration system and has two natural frequencies (f _t , f _d ). The reason is that there are two spring systems having different spring constants between the test motor 1 and the flywheel 3 and between the flywheel 3 and the energy absorbing generator 2. Here, considering the extreme case where the inertia moment (I _f ) of the flywheel 3 is assumed to be infinite, the two natural frequencies f _t and f _d are as follows.
f _t = 1 / 2π × √ (K _n / I ₁ )
f _d = 1 / 2π × √ (K _d / I ₂ )

In the above, since K _n is relatively large, f _t is large, i.e., a large natural frequency. On the other hand, since K _d is relatively small, f _d is small, that is, a small natural frequency.
Since test the vibration of the motor 1 itself, the natural frequency f _t is large, the vibration force almost all through rotating shaft system including a spring constant of the torque detection device 4, but transmitted to the flywheel 3, the moment of inertia Since (I _f ) is very large, there is almost no influence of the vibration force.
On the other hand, the drive motor which is the energy absorbing generator 2 also has a vibration source and generates vibration. However, since the vibration (K _d ) is small, this vibration is hardly transmitted to the flywheel 3 and is used to vibrate the drive motor itself.
Therefore, if the rotary shaft system is configured as described above, vibration from the drive motor that is the energy absorbing generator 2 can be eliminated, and the torque fluctuation of the test motor 1 can be accurately detected by the torque detector 4. It becomes possible to measure.
That is, when the vibration removal coupling 5 is a rubber coupling having a relatively small spring constant, the torsion spring constant (of the rotating shaft system) is increased by making the spring constant of the torque detector 4 relatively large. K _n ) can be made relatively large as a whole, which can increase the natural frequency f _n ≈½π × √ (K _n / I ₁ ) of the measurement system, and the measurement frequency is It is possible to measure at a high case.

A description will be given of making the spring constant of the torque detector 4 relatively large. Various structures of torque detectors are known in the market. In principle, the torque detector detects torsion of the torsion bar, but the so-called torsional differential is detected by coupling both ends of the torsion bar to the motor and the load device via the coupling. The spring constant of the differential torque detector is relatively small.
On the other hand, for example, a torque detector manufactured by Kyowa Denki Co., Ltd. does not use a coupling that lowers the spring constant. The so-called high-rigidity torque transducer of the type that measures as a direct strain has a large spring constant.
As described above, the spring constant of the torque detector is determined by design, and in the case of the same design concept, the detector output and the spring constant are inversely proportional. Considering selection of the natural frequency of the measurement system, it is determined as a design specification at the request of the user. An example of the main design specifications of the torque detector is shown below.
Rated load ± 15N ・ m,
The natural frequency f _n ≈1 / 2π × √ (K _n / I ₁ ) is about 2 kHz (target)
In the above, the moment of inertia I ₁ of the test motor shall be 10 kg · cm ^2.

  Next, an embodiment of the measuring apparatus according to the present invention shown in FIG. 3 will be described. FIG. 3 shows a state in which the drive motor (energy absorbing generator) 2, the vibration removing coupling 5, the flywheel 3, the torque detector 4, and the test motor mounting portion 61 are assembled on the gantry 60. , (A) is a top view, (b) is a front view, and (c) is a side view.

  According to the present invention, it is possible to provide a torque fluctuation measuring device and a measuring method capable of accurately measuring the torque fluctuation caused by the wow flutter, jitter, cogging and the like in the motor under measurement. Further, by increasing the spring constant of the measurement system (torsional vibration system), it is possible to measure with high accuracy even when the measurement frequency is high.

1: Test motor, 2: Drive motor (energy absorption generator), 3: Flywheel, 4: Torque detector, 5: Coupling for vibration removal, 6: Controller for generator control, 7: Speed display 8: regenerative resistor, 9, 10: data logger for measuring the motor characteristics of the test, recorder, 11: controller for rotating the motor, 12: computer for system control, 60: mount, 61: mounting part of the test motor.

Claims (5)

A torque fluctuation measuring device for a rotary motor, comprising a test motor (1) as a motor to be measured, a torque detector (4) for detecting torque by twisting of the shaft, and a rotating shaft of the test motor In a torque fluctuation measuring device comprising an energy absorbing generator (2) connected via a torque detector (4) and operating as a drive motor up to a set number of revolutions and thereafter acting as a power generation brake ,
A flywheel (3) having a larger moment of inertia than the moment of inertia (I ₁ ) of the motor under test (1) between the energy absorbing generator (2) and the torque detector (4). A torque fluctuation measuring device comprising: The inertial moment (I _f ) of the flywheel is an inertial moment that is sufficiently large so that the fluctuation of the angular velocity of the rotating shaft based on the rotation of the energy absorbing generator (2) can be ignored. 1. The torque fluctuation measuring device according to 1.   The rotation shaft of the generator (2) for energy absorption and the rotation shaft of the flywheel (3) are connected via a coupling (5) for vibration removal. Torque fluctuation measuring device. A method for measuring torque characteristics of a rotary motor using the torque fluctuation measuring device according to any one of claims 1 to 3, wherein the torsion spring constant of the rotating shaft system including the spring constant of the torque detector (4). By increasing K _n ), the natural frequency f _n ≈1 / 2π × √ (K _n / I ₁ ) of the measurement system is increased, thereby enabling measurement when the measurement frequency is high. Torque fluctuation measurement method characterized by The vibration removal coupling (5) in the torque fluctuation measuring device according to claim 3 is a rubber coupling having a relatively small spring constant, and the spring constant of the torque detector (4) is relatively large. The torsion spring constant (K _n ) of the rotating shaft system is relatively large as a whole, thereby increasing the natural frequency f _n ≈½π × √ (K _n / I ₁ ) of the measurement system. Torque fluctuation measurement method.