JPH1114471A - Micro torque measuring device - Google Patents

Abstract

(57) [Problem] To provide an apparatus for measuring a minute torque with good reproducibility. SOLUTION: A measured mechanism 10 whose torque is measured,
A load application portion 31 coupled to the rotation axis of the mechanism to be measured 10 to which a load is applied, and a liquid 2 whose viscosity value is known or measured in advance and applies a load to the load application portion 31
And a container 1 for storing the liquid 2, a load variable means 6 for changing a load by changing a viscosity coefficient of the liquid 2, and a rotation speed detector 5 for detecting a rotation speed of the load application portion 31. A minute torque measuring device that changes the load applied to the mechanism to be measured 31 by the means 6 and measures the torque based on the rotation speed of the load application portion 31 at that time. As a result, the fluctuation of the frictional force as a torque fluctuation factor is eliminated, so that a minute stress can be accurately measured.

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 torque of an arbitrary rotating mechanism, particularly, a minute torque.

[0002]

2. Description of the Related Art FIG. 11 shows a conventional apparatus for measuring the torque of a rotating mechanism. In this example, a thin wire 13 is wound around a pulley 12 of a motor rotating shaft 11 and the pulley 12 and the thin wire 13 are wound.
A load torque is applied to the motor by utilizing the slip at the motor. A weight 14 serving as a preload is attached in the direction of gravity of the wound fine wire 13, and a load converter 15 such as a precision balance is attached below the weight 14. As shown in FIG.
Are mounted at a certain angle θ, and by changing this angle θ, the load torque to the motor is made variable. In the state where the rotation torque is not applied, the load converter 15
Indicates the weight of the preload weight 14. Next, the thin wire 13 is attached at an appropriate angle θ, and when the motor is rotated in the direction of the arrow, the preload weight 14 obtains a lifting force. The minute load change is detected by the load converter 15. Further, by increasing the mounting angle θ of the thin wire 13, the load torque is increased and the motor rotation speed is reduced. By detecting the load change at each rotation speed, the torque at various rotation speeds can be measured. Further, Japanese Patent Application Laid-Open Nos.
No. 62039 discloses that a columnar weight rotatably suspended by a piano wire is immersed in a liquid in a container, the container is rotated at a constant speed, and the angle of the weight which is rotated by the viscosity of the liquid is measured. A torque sensor for measuring a minute torque applied to a weight or a viscosity of a liquid is disclosed.

[0003]

However, the former FIG.
In the prior art shown in FIG. 1, since the slip between the preload weight 14 and the thin wire 13 is used, a complicated phenomenon called friction is interposed. In particular, when a small torque of a small machine is measured, the reproducibility of the measurement is reduced. There were difficulties. Further, in the torque sensor disclosed in the latter publication, since the container connected to the motor of the object to be measured is rotated, the mass of the container generates a load torque on the motor. The load torque was too large, and there was a problem to apply. Accordingly, an object of the present invention is to provide a high-precision minute torque measuring device capable of measuring a minute torque with good reproducibility.

[0004]

In order to achieve the above object, a minute torque measuring device according to the present invention comprises a mechanism to be measured whose torque is to be measured, and a load coupled to a rotating shaft of the mechanism to be measured. The load application site, the value of the viscosity coefficient is known or measured in advance, and a liquid that applies a load to the load application site, a container that stores the liquid, and the load is changed by changing the viscosity coefficient of the liquid. A variable load means for changing, and a rotation detector for detecting the number of rotations of the load application part, wherein the load applied to the mechanism to be measured is changed by the load variable means, and the torque is determined by the number of rotations of the load application part at that time. It is to be measured.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A torque measuring method according to the present invention is a method for measuring a torque from a rotation speed when a load application portion connected to a rotating shaft of a mechanism to be measured is rotated in a liquid whose viscosity coefficient is measured in advance. Is what you want. In particular, the relationship between the number of rotations of the mechanism to be measured and the torque is measured by rotating in a liquid held at various values of the viscosity coefficient. Further, as means for changing the viscosity coefficient of the liquid, a heating / cooling device may be provided, or a liquid injection pipe and a liquid discharge pipe for changing the concentration of the liquid as a polymer aqueous solution are provided in the container. Is also good. In addition, when the shape of the load application portion to be rotated in the liquid is cylindrical or disk-shaped, the measurement range of the torque is widened. By such means, the fluctuation of the frictional force as a torque fluctuation factor is eliminated, so that a minute torque can be accurately measured.

[0006]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a minute torque measuring device according to the present invention. First Embodiment FIG. 1 is an explanatory diagram showing a first embodiment of the present invention. In the liquid 2 in the container 1, a load application part 31 connected to the rotation shaft of the mechanism to be measured 10 via the connection shaft 4 is arranged. The rotation speed of the load application part 31 is detected by the rotation detector 5 as the rotation speed of the connection shaft 4. The container 1 is provided with a heating / cooling device 6 for changing the temperature of the liquid 2. In the container 1, a temperature sensor 9 for measuring the temperature of the liquid 2 is provided. If the load torque application site has a simple shape, a calibration curve can be created by hydrodynamic numerical calculation. For example, it is known that when a disk having a radius r ₀ is rotated at an angular velocity ω as shown in FIG. 5, the viscous torque M received by the disk is expressed by the following equation. ^{_{M = ρr 0 5 C f ·}} ω 2 , however, [rho: the density of the liquid, C _f: a constant. When the disk surface is smooth and sufficiently thin, rotates in a wide space, and the flow near the disk surface is laminar (La <flow when Re <(3 to 5) × 10 ⁵ ), C _f is It is expressed by an equation. C _f = 1.94 / √ (Re) where Reynolds number: Re = ωr ₀ ² / ν, ν = μ /
ρ: kinematic viscosity, μ: viscosity. For example, r ₀ = 10 ⁻² m ρ = 10 ³ kg / m ³ (water at 20 ° C.) μ = 1 × 10 ⁻³ N · s / m ² (water at 20 ° C.) ω = 2π × 20 s ⁻¹ (1200 rpm ), Re = 1.3 × 10 ⁴ M = 2.7 × 10 ⁻⁵ N · m. Using the values of such parameters, the relationship between the load torque generated by the disk and the rotational speed is determined as shown in FIG. When the temperature of the liquid is changed, the viscosity coefficient changes. Therefore, a calibration curve at a plurality of temperatures can be obtained as shown in FIG. For example, the viscosity coefficient of water is as follows. Temperature (° C) 0 20 40 60 80 μ (Ns / m ² ) 17.94 10.09 6.54 4.70 3.57

In this apparatus, the rotation speed of the mechanism to be measured 10 is measured. As shown in FIG. 8, the intersection of a straight line indicating the value of the rotational speed (a line extending perpendicularly from the measured value) and the calibration curve gives the torque generated by the mechanism 10 to be measured. By connecting the intersections at several temperatures, the torque-rotation speed characteristic (broken line) of the measured mechanism 10 can be obtained. The viscosity resistance can be changed by changing the composition of the liquid. In addition, by changing the shape of the load application portion to various shapes, a wide range of torque can be measured. If it is difficult to calculate the load torque when using something other than a disk as the load application part, prepare a plurality of standard torque generating mechanisms and use a disk for each standard torque generating mechanism. 8, the relationship between the generated torque and the rotation speed P ₁ , P ₂ ,
Determine the P _3. Next, change the disk to another shape,
Measure the number of rotations when combined with each standard torque generating mechanism. As shown in FIG. 10, the intersection of a straight line indicating the number of rotations (a straight line extending perpendicularly from the measured value) when each of the standard torque generating mechanisms is used and the corresponding generated torque characteristic curve is connected. A calibration curve (broken line) for the application site can be created. Further, if the same measurement is performed while changing the viscosity of the liquid, a calibration curve for different viscosities as shown in FIG. 7 can be obtained. As the liquid 2, water, an aqueous solution of a polymer, oil, or the like is used depending on the measurement target. When a small disk or round bar is used as the load application part 31, the applied load is small, and therefore, it is particularly suitable for measuring a minute torque. As the heating / cooling device 6, for example, a Peltier element is used. For example, when the liquid 2 is water, changing the temperature from 50 ° C. to 10 ° C. increases the viscosity coefficient to nearly three times, so that the magnitude of the load resistance can be approximately tripled. Thereby, the rotation speed of the rotation mechanism 10 changes, and the magnitude of the torque at different rotation speeds can be measured. When measuring a small torque, the liquid 2
There is also an advantage that the heat capacity is small and the temperature can be changed quickly because the amount of slag is small.

Second Embodiment FIG. 2 is an explanatory diagram showing a second embodiment of the present invention. In this embodiment, instead of the heating / cooling device 6 of the first embodiment,
This is an example in which the viscosity is changed by exchanging the liquid 2 with a liquid having a different composition. In order to exchange the liquid 2, the liquid injection pipe 7
And a discharge pipe 8. In order to change the viscosity coefficient of the liquid 2, the concentration of the aqueous polymer solution is changed. Further, if a configuration as shown in FIG. 3 in which the heating / cooling device 6 is added to the example in FIG. 2 is used, a wider viscosity range can be used. At this time, after the viscosity coefficient is roughly changed by changing the composition of the liquid 2, it can be finely changed by a temperature change.

Third Embodiment FIG. 4 is an explanatory view showing a third embodiment of the present invention. In the examples shown in FIGS. 1, 2, and 3, a round bar or a disk is used as a load application portion, and a configuration particularly suitable for measuring a minute torque is employed. On the other hand, by replacing the load application part 31 with a screw type load application part 32 as shown in FIG. Various other shapes such as a cylinder and a sphere can be applied as the shape of the load application site, and can be selected according to the measurement target.

[0010]

As described above, according to the present invention, a load application portion that transmits torque from a mechanism to be measured and rotates in a liquid, and a rotation detector that detects the number of rotations of the load application portion. Having a means for measuring the torque from the value of the known or pre-measured viscosity coefficient of the liquid with respect to the load application site and the number of rotations detected by the rotation detector, accurate minute torque, And easy measurement becomes possible.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a first embodiment of the present invention.

FIG. 2 is an explanatory diagram 1 of a second embodiment of the present invention.

FIG. 3 is an explanatory diagram 2 of the second embodiment of the present invention.

FIG. 4 is an explanatory diagram of a third embodiment of the present invention.

FIG. 5 is an explanatory diagram for explaining the principle of the present invention.

FIG. 6 is an explanatory diagram of load torque-revolution speed characteristics.

FIG. 7 is an explanatory diagram of load torque-revolution speed characteristics.

FIG. 8 is an explanatory diagram of a method for obtaining a torque-rotation characteristic of a mechanism to be measured from a load torque-revolution number characteristic.

FIG. 9 is a graph showing the relationship between the generated torque and the rotation speed obtained for a plurality of torque generating mechanisms.

FIG. 10 is an explanatory diagram of a method for obtaining a calibration curve for a load site.

FIG. 11 is a schematic diagram showing a configuration of a conventional torque measuring device.

[Explanation of symbols]

1 container, 2 liquids, 31 load application site (round bar type),
32 Load application site (screw type), 4 connecting shaft, 5
Rotation detector, 6 heating / cooling device, 7 liquid injection tube,
8 liquid discharge pipe, 9 temperature sensor, 10 measured mechanism,
11 motor rotation shaft, 12 pulley, 13 thin wire, 14
Weight, 15 load transducer, 20 motor, 21 container,
22 liquid, 23 load application part, 24 axis, 25 tachometer, 26 torque meter, 27 heating / cooling device

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tomohiro Matsuo 2-1 Kurosaki Castle Stone, Yawatanishi-ku, Kitakyushu-shi, Fukuoka Prefecture Yasukawa Electric Co., Ltd.

Claims (5)

[Claims] 1. A mechanism to be measured whose torque is to be measured, a load application site coupled to a rotation axis of the mechanism to be measured and to which a load is applied, and a value of a viscosity coefficient is known or measured in advance, and the load is A liquid that applies a load to an application site, a container that stores the liquid, a load variable unit that changes the load by changing a viscosity coefficient of the liquid, and a rotation detector that detects a rotation speed of the load application site. A minute torque measuring device, comprising: changing a load applied to the mechanism to be measured by the load varying means; and measuring a torque based on a rotation speed of the load application portion at that time. 2. The minute torque measuring device according to claim 1, wherein the load variable means is a heating / cooling device for changing a temperature of the liquid. 3. The microtorque measuring device according to claim 1, wherein the load variable means uses the liquid as a polymer aqueous solution, and a liquid injection pipe and a liquid discharge pipe for changing the concentration are provided in the container. . 4. The minute torque measuring device according to claim 1, wherein the shape of the load application portion is a column. 5. The minute torque measuring device according to claim 1, wherein the shape of the load application portion is a disk shape.