SU746216A1 - Apparatus for measuring torque - Google Patents

Description

; 54) DEVICE FOR MEASURING THE TORQUE The invention relates to force measuring technique and can be used, for example, for measuring the torque of rotary switches. The tensometric dynamometer for measuring the torque containing a sensing element located between two parts of a twisting rod, made in the form of longitudinal plates, radially spaced and equidistant from the axis of the rod, and strain gages, does not provide the required accuracy of measurement 1. The closest in technical essence and the achieved result to the proposed is a device for measuring torque, containing a sensitive element in the form of an elastic plate, cantilever mounted on the shaft of an adjustable electric drive and. connected through the receiving half coupling with the axis of the test product and indicator 2. The disadvantage of this device is the low measurement accuracy associated with the lack of compensation for the parasitic bending moment due to the action of the own weight of the elastic plate. The purpose of the invention is to improve the measurement accuracy. This goal is achieved by the fact that a parasitic bending moment is inserted into the device from the action of the own weight of an elastic plate with a continuous ring resistive element and a slider, kinematically connected to the shaft of the electric drive and installed with the possibility of in-phase rotation with an elastic plate, and the indicator is made with an adjustable zero of reference, with the tap point of the resistive element and the slider connected to the input of the zero adjustment of the indicator. FIG. 1 shows a block diagram of the device; in fig. 2 (a, b, b, d) are the phase positions of the elements of the device; in fig. 3 (a, 6, b, d) are diagrams of dependences of the device parameters on the phase positions of the elements of the device. The device for measuring the torque (Figs. 1 and 2) contains an adjustable electric drive in the form of the electric drive 1 itself and a regul74741fi

power source 2, the input of which is connected to the sensor 3 of the angle of rotation of the electric drive shaft 1. On the shaft of the electric drive 1, the sensitive element in the form of a cantilever elastic plate 4 is fixed with stencil resistors 5. The free end of the elastic plate 4 is connected through the receiving coupling half 6 to the axis of the test product 7 The strain gages 5 are connected to a torque indicator 8 which is made with an adjustable zero reference. With the shaft of the electric drive 1, kinematically coupled the slider 9 of the rheostat-10 kOMYendatsy parasitic bending moment from the action of the own weight of the elastic plate4 having a continuous ring resistive element with one point, retraction 11. The slider 9 of the rheostat 10 has an infinite (over 3.60 °) angle of rotation and is in phase with the elastic plate 4, and the outlet point 11 is located on the horizontal line 12 passing through the geometric center 13 of the ring resistive element of the rheostat 10, and on that side relative to this center 13, from which r An orientally oriented elastic plate 4 with tensor resistors 5 produces (in the course of the device operation) a sign with a negative error signal.

The retraction point 11 and the slider 9 of the rheostat 10 are connected to the input of the zero reference of the torque indicator 8.

FIG. 2 (a, 5, 6, d) some phase positions of the elastic plate 4 and the slider 9 of the device rheostat 10 are shown; the direction of rotation 14 of the elastic plate and slider; force vector 15 acting on the elastic plate 4, as a response from the driven half-coupling b weight vector of gravity (weight) 16 of the elastic plate 4, reduced to the center of gravity of this plate; conditional reference point 17 of the angle of rotation of the elastic plate 4 and the slider 9; shoulder L strength 15 and shoulder strength 16.

Points 18-21 (see Fig. 3a, 5, b, d) show the values of the parasitic bending moment M and the corresponding electric output signal U with the resistance strain gages, the equivalent moment (the sum of the measured and the parasitic moment) and the corresponding output equivalent electrical signal Uekv from strain gauges, resistor R resistors and reference zero displacements for the phase positions (rotation angles) of the elements shown in FIG. 2 and point 18, in FIG. 26 by point 19, in FIG. 2b by point 20 and in FIG. 2g point 21.

The device works as follows.

From the regulated power supply 2, the drive 1 is supplied with a rising supply voltage from zero. Under the action of an increasing current through the windings of the electric drive, its torque increases accordingly. Upon reaching a certain critical level of torque, the shaft of the electric drive 1 begins to turn through the elastic plate 4 and the receiving coupling half b of the axis of the test product 7.

When the shaft of the electric drive 1 is rotated, the sensor 3 of the angle of rotation of the electric drive shaft issues a command to the adjustable power supply 2 to stop the increase in the supply voltage of the electric drive 1.

When torque is transmitted from the shaft of the electric drive 1 to the axis of the test article 7, the elastic plate 4 with the strain gages 5 is deformed. The degree of deformation of the elastic plate 4 is determined by the magnitude of the transmitted torque. Depending on the magnitude of the torque, the strain gages 5 emit the corresponding electrical signal to the torque indicator 8, which shows the result of the measurement.

In the process of rotating the elastic plate 4 with the strain gages 5, depending on the phase position of the elastic plate, the measurement result is affected by the parasitic bending moment M from the action of the own weight 16 of the elastic plate 4.

FIG. 2 (a, s, b, d) it can be seen that the magnitude and sign of the measured torque (product of force 15 by arm L) has a constant value and a constant sign, regardless of the phase position ynpyrofi of plate 4.

Since both moments, both measurable (constant in magnitude and sign) and parasitic (variable in magnitude and sign) act on one common elastic plate 4, the latter reacts to the equivalent moment Meq / equal to the algebraic sum of the acting moments.

Accordingly, the electrical output signal U from the strain gauges 5 is the algebraic sum of the signals from each of the moments.

Simultaneously, with the rotation of the elastic plate 4, the synchronous and in-phase rotation of the slider 9 of the rheostat 10 is carried out.

The nature of the change in the resistance of the rheostat from the phase position (angle of rotation H) of the slider 9 is shown in Fig. 3b, and the displacement of the zero reference point of the torque indicator 8 caused by it is shown in FIG. Sg.

Claims (2)

With the above structural design of the rheostat, the kinematic connections of its engine and the corresponding orientation of the retraction point during operation of the device, the resistance of the rheostat 1Q is periodically changed from zero (point 21, fig. 3b) when its engine 9 is rotated every 180. At that resistance corresponds to each horizontal position of the elastic plate, 4, in which the signal from the parasitic bending moment causes the maximum rise of the indications of the torque indicator 8 (point 19, fig. ZB and min m of resistance (zero) corresponds to each other horizontal position of the elastic plate at which the signal from the parasitic bending moment causes the maximum decline of the indicator readings (point 21 of Fig. 38). The maximum s1 of the resistance of the rheostat 10 is chosen such that its zero offset of the indicator to the negative side is equal the absolute value of the signal from the parasitic bending moment, causing the maximum rise of the readings. With synchronous and in-phase rotation of the slider 9 of the rheostat 10 and the oyrugy plate 4 with the strain gages 5, mutual compensation of these two factors influencing the readings of the torque indicator 8 is ensured. From the mapping shown in FIG. CSA - FIG. 3 g it can be seen that an increase in the parasitic bending moment (section 21-18-19, fig. In) corresponds to an increase in the equivalent electrical signal USKB (section 21-18-19, fig. 35 to which, in turn, corresponds to an increase in resistance (section 21-18-19, fig. 3b), causing the zero of the indicator 8 to shift to the negative side (section 21-1 of fig. 3g). And, conversely, to reduce the parasitic bending moment (section 19-20-21, fig. Over ) corresponds to a decrease in the equivalent electrical signal (section 1920-21, fig. 3b), which, in turn, corresponds to a decrease in resistance of the rheostat (section 19-20-21, fig. 3b) causing the zero of the indicator 8 to shift towards the half (section 19-21, fig. 3g). Such an embodiment of the device will ensure that the indicator readings are independent of the parasitic bending moment and consequently, an increase in measurement accuracy. Formula of Invention A device for measuring torque, containing a sensitive element in the form of an elastic plate, cantilever mounted on the shaft of an adjustable electric drive and coupled through a receiving the coupling half with the axis of the tested product, and the indicator that differs from the fact that, in order to increase the measurement triciness, a rheostat of compensation of the parasitic bending moment from its own action is introduced into the device; about the weight of the elastic plate with a continuous ring resistive element and a slider, kinematically connected to the shaft of the electric drive and installed with the possibility of in-phase rotation with an elastic plate, and the indicator is made with an adjustable zero point, the tap point of the resistive element and the slider are connected to the input Gulirovka zero readout indicator. And (Stochniki information taken into account during the examination 1. USSR author's certificate 474713, cl. G 01 L 3 / JO, 1973. 2. Vysotsky A.A. Dynamometer of agricultural machines. M., Mashinostroenie, 1968, p. 125 (prototype). // x / x / w // v Vvy Fig-l