SU1654671A1 - Torsion balance - Google Patents

Abstract

The invention relates to weighing technology, namely, devices for measuring small forces. The purpose of the invention is to improve the accuracy of the balance by increasing the sensitivity to small torsional displacements of the rocker arms, g also by reducing the influence of fluctuation horizontal plane-parallel movements of the rocker arms on the measurement result. The device includes a yoke 4 suspended from the bracket 2, a device 5 for fastening the sample 6 on the rocker arm, and a system for measuring the horizontal displacement of the rocker arm. New to the scale is that the horizontal displacement measurement system includes two parallel-connected capacitive displacement sensors. Electrically connected movable plates 8 and 9 of these sensors are arranged vertically and fixed on the yoke 4. Fixed plates fixed to support 1 are 10, 11 capacitive sensors located on opposite sides of a plane passing through movable plates 8 and 9. Thanks to this design of the displacement measurement system with the fluctuation plane displacement of the rocker, the readings of the sensors mutually compensate each other, and when the rocker turns around the vertical axis, their readings add up. This leads to an effective suppression of the contribution of plane oscillations to the measured displacement of the rocker arms and to an increase in the accuracy of the balance. 2 Il. with С ON СЛ Ј О XI

Description

The invention relates to weighing technology, namely torsional weights, and can be used to measure small forces acting on various objects in electric, magnetic and gravitational fields.

The aim of the invention is to increase the measurement accuracy by increasing the sensitivity of the balance to small torsional displacements of the rocker arms, as well as by reducing the influence of fluctuation horizontal plane-parallel movements of the rocker arms.

FIG. 1 shows a kinematic diagram and an electrical block diagram of torsional weights; Fig. 2 shows moving and stationary plates of capacitive sensors, top view (the principle of measuring the angular displacement of the rocker arm under the horizontal force and simultaneous flat displacement of the rocker arm is explained).

The balance contains a support platform 1 with a bracket 2. to which, using a weight 3, the beam 4 is freely suspended, equipped with a system 5 for fastening the sample 6 in the zone of external force created by an electromagnet 7. On the rocker arm on either side of its axis of rotation vertically Two grounded metal plates 8 and 9 are fixed and electrically interconnected. These plates are movable plates of two capacitive sensors. The corresponding fixed plates 0 and 11 of the same sensors are vertically mounted on platform 1, and one of the fixed plates is equipped with the device | 2, which allows the distance between the plates of one of the sensors to be adjusted. The balance is equipped with a switch 13, with which the inductor 14 can be connected to the plate 10 or to the plate 11, or both at the same time. The oscillatory circuit formed by the V4 coil with capacitive sensors connected to it is connected through the coupling coil 15 to the input of the capacitance measuring unit 16 of the LC circuit. The output of block 16 is connected to the input of system 17 of registration.

Scales work as follows.

In the initial state, the electromagnet 7 is turned off. After securing sample 6 on the rocker arm 4 and calming the latter in an equilibrium position (FIG. 2, dashed line), plates 10 and 11 are alternately connected using switch 13 to coil 14, thereby measuring using block 16 and the system 17 of the container flag Cf and C§. In tqm cl. If

C and CЈ are different from each other, using the device 12 to establish a position of the plate 11 such that

C and C. After that, the switch 13 is transferred to a position in which both plates 10 and 11 are connected to the coil 14, i.e. both sensors are connected in parallel. The system 17 registers the value

C 4 - C 2C. Then, an electromagnet 7 is turned on, the force of which acts on the sample 6 in the direction indicated by an arrow in FIG. 2 and causes the core 4 to twist at an angle a proportional to the external force, which leads to a change in the total capacitance of the sensors by the DS value recorded by the system 17. Since the initial distance between the plates (b) and inductance (L) are known device constants, the twist angle is calculated by the formula

d, AC d} 143 + c2. c + c d}

where the term containing the (horizontal displacement of the entire rocker due to the fluctuation processes) is zero due to the equality of the capacities

Claims (1)

C and C5 The magnitude of the external force acting on the sample is judged by the coefficient of proportionality between the external force and the angle of torsion of the rocker arm. Due to the low sensitivity of the balance to flat movements of the rocker, it becomes possible to detect extremely small torsional displacements, i.e., the measurement accuracy is improved. Claims of torsion scales, including a support platform, a bracket mounted on the platform with a rocker suspended on it, an orifice mounting device on the arm, and a horizontal displacement meter for the rocker arms, different in that. that, in order to increase accuracy, the device for measuring the displacement of the rocker arm is made in the form of two parallel-connected capacitive sensors equipped with movable and fixed plates, the movable plates of the sensors being fixed: on the ends of the rocker arm and the vertical plane, and under-sized plugins are mounted on a supporting platform on opposite sides of plane passing through the moving plates. FIG. 2