JPH06129920A - Micro torque measuring instrument - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a micro torque measuring instrument capable of highly accurate measurement without variation in torque measurement values. [Structure] A motor (6) to be measured is attached to a torque measuring shaft (7) supported in a non-contact manner with an air bearing (8), and an electromagnetic brake (9) capable of applying an arbitrary load in a non-contact manner is used. The torque acting on the stator side is detected by a load detector (5) such as an electronic balance, and the rotation speed of the motor is measured by a rotation sensor (10) fixed in a non-contact manner.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for measuring a small torque of a small motor.

[0002]

2. Description of the Related Art Conventionally, there is a minute torque measuring device as shown in FIG. In this rotational torque measuring device, a motor rotating shaft 1 and a pulley 2 are fixed, a thin wire 3 is wound around this pulley 2, and a slip between the pulley 2 and the thin wire 3 is used to generate a load rotating torque in a motor. In the direction of gravity of the wound thin wire 3, a weight 4 is added as a load to be preliminarily applied.
Is attached, and the load detector 5 such as a spring balance is attached in the upward direction. As shown in FIG. 2, the load detector 5 is attached at a certain angle θ, and the load torque to the motor is changed by changing this angle θ. The load detector 5 indicates the weight of the weight 4 when no rotational torque is applied. Next, thin line 3
The weight 4 gains the force to be lifted when is mounted at an appropriate angle θ. The load detector 5 detects the minute load change. Further, by increasing the mounting angle θ of the thin wire 3, the load torque and the motor rotation speed are changed, and the torque at the motor rotation is measured by detecting the load at each rotation speed.

[0003]

In the prior art, since the frictional force acting between the yarn and the pulley can be changed to maintain a constant load condition relatively easily, it is used for a relatively large rotary motor. Was there. However, in this motor torque measuring method, when the motor itself is made smaller,
Since the motor torque is also miniaturized, the motor cannot rotate even with a slight change in frictional force, it is difficult to detect the torque, and it is difficult to apply a small amount of frictional force to a certain amount, which causes variations in the rotational torque measurement results. There was a problem. Therefore, an object of the present invention is to provide a micro torque measuring device that can measure a torque measurement value with high accuracy without variation.

[0004]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention mounts a motor to be measured on a torque measuring shaft which is supported in a non-contact manner with an air bearing so that an arbitrary load can be applied in a non-contact manner. A brake is used, and as the motor torque at that time, the torque acting on the stator side of the motor is detected by a load detector such as an electronic balance.

[0005]

Since the stator side of the motor is attached to the torque measuring shaft using the air bearing by the above means, torque loss due to friction is eliminated, and a small load can be applied in a contactless manner by the electromagnetic brake. Therefore, it is possible to eliminate variations in the load torque in the minute rotational torque range.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A concrete embodiment of the present invention will be described below with reference to FIG. In the figure, 6 is a motor to be measured,
It is composed of a stator 61, a rotor 62, and a motor rotating shaft 63. Reference numeral 7 is a torque measuring shaft, 8 is an air bearing, and the torque measuring shaft 7 is supported in a non-contact and frictionless state. Reference numeral 9 is an electromagnetic brake, 91 is a disk fixed to the shaft end of the motor rotating shaft 63 for generating a load, and 92 is an exciting coil for generating an eddy current in the disk 91 to control the rotation speed of the motor. Reference numeral 10 is a rotation sensor that measures the rotation speed of the disk 91 in a non-contact manner, and reference numeral 4 is a weight, which is suspended by a thin wire 3 on a rod 71 extending from the torque measuring shaft 7. Reference numeral 5 is a load detector, which uses an electronic balance.
It is balanced with. Now, the stator 6 of the motor 6
No. 1 exciting coil (not shown) is applied with a voltage to rotate the rotor 62.
Rotate with no load. The coil of the stator 61 is held so as to move freely, and when torque is generated, a reaction force corresponding to the torque acts on the stator 61. At this time, the torque measuring shaft 7 to which the stator 61 of the motor is attached is supported by the non-contact support mechanism of the air bearing 7 in a state in which there is no frictional force, and therefore the rotational force is obtained by the reaction force of the rotational torque of the motor 6. . When the stator 61 rotates, the torque measuring shaft 7 connected thereto rotates, the rod 71 rotates, and the weight 4 is lifted in the direction opposite to the direction of gravity. Weight 4
Is lifted, the load of the balanced load detector 5 changes. The torque can be obtained by multiplying the change of the load by the radius of the rod 71. If the rotation speed at this time is read by the rotation sensor 10, the torque at this rotation speed can be measured. Next, if a constant current is applied to the exciting coil 92 of the electromagnetic brake 9 so as to reach the set rotation speed, a restraining force based on the generation of an eddy current is applied to the disk 91, and the rotation speed of the rotor 62 is lowered to set the rotation speed. It becomes the number of rotations. At this time, the torque increases on the stator 61 and a reaction force corresponding thereto acts, so that the load of the load detector 5 also changes accordingly. The torque can be obtained from the value of this load in the same manner as above. If the rotation speed at this time is also read by the rotation sensor 10 in the same manner as above, the torque at that rotation speed can be known. In the same manner, the rotation speed-torque curve can be obtained by sequentially increasing the current of the exciting coil 92 of the electromagnetic brake 9 and measuring the torque at each rotation speed. The rotation speed is set by an externally attached rotation sensor 11 which detects the rotation speed and feeds back a current value to be applied to the electromagnetic brake 10 so that the rotation speed can be set to an arbitrary rotation speed by using a control circuit (not shown). In this way, a constant number of rotations is controlled.
It was found that the rotation speed-torque curve obtained in this manner had a significantly reduced variation, good reproducibility, and high accuracy as compared with the conventional method. Further 1500 rp
It has been found that even in a high speed region of m or more, a minute torque is detected.

[0007]

As described above, according to the present invention, the electromagnetic brake is used for non-contact braking, and the air bearing is used to eliminate the loss due to friction. Therefore, it is possible to provide a torque detector that can accurately measure the torque and can detect a minute torque with high accuracy.

[Brief description of drawings]

FIG. 1 is a sectional view of a micro torque measuring device of the present invention.

FIG. 2 is a sectional view of a conventional torque measuring device.

[Explanation of symbols]

1 Motor Rotating Shaft 7 Torque Measuring Shaft 2 Pulley 8 Air Bearing 3 Thin Wire 9 Electromagnetic Brake 4 Weight 91 Disc 5 Load Detector 92 Excitation Coil 6 Motor 10 Rotation Sensor 61 Motor Stator 62 Motor Rotor 63 Motor Rotating Shaft

Claims (3)

[Claims] 1. A torque measuring shaft for mounting a stator of a motor to be measured, an air bearing for supporting the torque measuring shaft in a non-contact manner, and a load for detecting a load based on a torque provided at a shaft end of the torque measuring shaft. A detector, an electromagnetic brake including a disk fixed to the shaft end of the motor to be measured, an exciting coil provided on both surfaces of the disk in a non-contact manner, and a rotation sensor for detecting the number of rotations of the motor in a non-contact manner. A micro torque measuring instrument characterized by 2. The minute torque according to claim 1, further comprising a control device that feeds back the current of the electromagnetic brake so that the rotation speed of the measured motor becomes constant based on the signal of the rotation sensor. Measuring instrument. 3. The load detector is configured to detect the load by balancing a weight hung on the outer circumference of the shaft end of the torque measuring shaft through a thin wire by an electronic balance. And the micro torque measuring device described in 2.