JPS59212731A - Torque detector - Google Patents

Abstract

PURPOSE:To eliminate the unbalanced weight of the whole body of a torque detector and to prevent the detector from vibrating by installing the 1st and 2nd springs having the same number of turns and different diameters under a condition where they are fitted concentrically with their fitting position being displaced by 180 deg. from each other and setting the moment of the unit angle of each spring so as to become equal to each other. CONSTITUTION:The 1st spring 20 and 2nd spring 30 have the same winding direction and number of turns and different winding diameters. The springs 20 and 30 are arranged concentrically and fixed to adapter plates 5 and 6 in such a way that their beginning ends 21 and 31 are fitted to the adapter plate 5 at positions which are displaced by 180 deg. from each other and their ending ends 22 and 32 are fitted to the adapter plate 6 at position which are displaced by 180 deg. from each other. Moreover, their cross-sectional areas are set so that the areas are in inverse proportion to the square of the winding radius. When such an arrangement is made, flexure is produced in the springs in accordance with torque and, even when the weight distribution of each spring is changed, the change in the weight distribution denies each other and the unbalanced weight of the whole body is eliminated, and thus, occurrence of vibrations can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to the configuration of a spring in a torque detector that detects one-rotation torque based on the deflection angle of a coil spring.

(Prior technology) A coil spring is inserted between the drive side and output side of the rotating shaft,
In a torque detector that causes a coil spring to deflect due to load torque, and detects torque by the amount of mutual deviation between spring mounting plates attached to both ends of the spring, the weight distribution of the coil spring changes due to the deflection of the coil spring. 6
It has the drawback that unbalanced vibration occurs due to rotation, making it unsuitable for use in high-speed machinery and precision equipment.

That is, as shown in FIG. Provide mounting plates 5 and 6 to face each other.

Both ends of the coil spring 7 are fixed to this mounting plate, and the displacement between the mounting plates due to the deflection of the coil spring 7 is detected by 1-position detectors 8 and 9, and the torque is detected based on the amount of displacement. Teral a 10 and 11 are position detection pieces of the spring mounting plate, and 12 and 13 are bearings.

(Problems with conventional technology) In the electric motor with a torque detector configured as described above,
The rotation system is balanced by keeping the output shaft 4 in an unloaded state, but when a load torque is applied to the output shaft 4, the spring 7 is deflected, and as shown in FIG.
B (the number of turns is shown as one for simplicity) is expanded into A' and B', and torque is detected from this deflection angle of 0. However, since the space between A' and 37 becomes a gap, the weights of the left and right sides of the coil spring are unbalanced, and one rotation induces unbalanced vibration.

(Structure of the present invention) In view of these points, the present invention has three drive shafts and four output shafts.
Using coil springs of different diameters having the same number of turns and having the same moment per unit angle, the mounting positions of the coil springs are offset by 180 degrees from each other.

They are arranged concentrically.

(Embodiment of the present invention) In the embodiment of the main parts shown in FIG. 3 and FIG. It is fixed.

10 and 11 are detection pieces, for example, permanent magnet pieces, and 20 is a coil-shaped piece (in the example, the number of turns is approximately 1) with one end 21 fixed to the spring mounting plate 5 and the other end 22 fixed to the spring mounting plate 6. The first spring 30 is a coil-shaped second spring having one end 31 fixed to the spring mounting plate 5 and the other end 32 fixed to the spring mounting plate 6. Therefore, the first spring 20 and the second spring 30 are arranged concentrically with the same winding direction and the same number of windings, and each winding diameter is different.
The ends 22 and 32 are fixed to the spring mounting plate 6 at a position offset by 180°, and their cross-sectional areas are inversely proportional to the square of the winding radius. .

(Function) When the spring retaining plate 6 fixed to the output shaft 4 deviates at an angle of 0 in the direction of the arrow in FIG. 6 side end 22 (for convenience of explanation, spring ends 21, 22 and 31, 32 in the no-load state)
are at the same angular position. ) moves to a position 22' deviated by θ, creating a gap 22-22 between it and the end 21.
, and the spring radius r1 increases to (r1+Δr1).

At the same time, the end 82 of the second spring 30 moves into the air gap 32-
32', and the spring radius r2 increases to r2+Δr2.

By the way, there is a relationship between the amount of deviation θ and the amount of increase △r in the spring radius, and 2π.
2)...Represented by (2). Here Wl・1～
・2 is the weight of the part that became a gap due to the deformation of the first spring and the second spring, W2-82. ・Sl, S2: cross-sectional area of the spring r: specific weight of the spring. If the unbalanced weight wr shown in equation (2) is O, then 81 r2+Δr2 82 r1+Δr1 By substituting and rearranging equations (1) and (3), the relationship 51r2 2 82 rl is established.

Therefore, the cross-sectional area S1 of the first spring 20 and the second spring 30
By changing the cross-sectional area S2 of , so that it is inversely proportional to the square of the radius of each splash.

The unbalance caused by the deflection of the spring can be reduced to O.

Note that the number of turns of the coil spring is not limited to one, and it goes without saying that the present invention can also be applied to a case where the coil spring is bent in a direction that reduces its diameter. Also.

Unbalance can also be eliminated if the coil is installed with both ends open at a certain angle under no load.

(Effects of the present application) In this way, the present invention provides the first and second springs with the same number of turns and different diameters concentrically and with their mounting positions offset by 180°, so that the moment of unit angle of each spring is In order to be equal, the tfi area is inversely proportional to the square of the diameter and proportional to the specific weight, so even if the springs are deflected in response to torque and the weight distribution of each spring changes, they cancel each other out. It is possible to eliminate the overall unbalanced weight, prevent the occurrence of vibration, and when used in precision machinery, there is no influence of vibration, and it is possible to perform highly accurate torque detection.

[Brief explanation of drawings]

Fig. 1 is a side sectional view of the upper half of a motor with a torque detector showing a conventional example, Fig. 2 is an explanatory view showing the state of deflection of a coil spring, and Fig. 3 is a main part showing an embodiment of the present invention. The upper half is shown in cross section in a side view. FIG. 4 is a cross-sectional view taken along line XX in FIG. 3, and FIG. 5 is an explanatory view showing the deflected state of the coil spring in the present invention. 3 is the drive shaft, 4 is the output shaft, and 5 and 6 are the spring mounting plates. 7 is a coil spring, 8 and 9 are position detectors, 20 is a first spring, 30 is a second spring, and 21, 22, 31, and 32 are spring ends. Figure 1 J4 Figure 5 n

Claims (1)

[Scope of Claims] 1. A torque detection device that detects rotational torque by inserting a coil spring between a drive side and an output side and using a deflection angle of the coil spring, which has the same number of turns and has a moment of unit angle. A first spring and a second spring having different diameters are provided, and the first spring and the second spring are arranged concentrically between a drive side and an output side, respectively. A torque detector characterized in that the mounting position is offset by 1800 degrees. 2. The torque detector according to claim 1, wherein the first spring and the second spring have the same stiffness and a cross-sectional area that is inversely proportional to the square of the diameter.