RU2819553C1 - Strain gage force sensor - Google Patents

Abstract

FIELD: instrumentation.

SUBSTANCE: invention relates to instrument making and can be used to create compact force sensors in the form of tumbler pillars. Elastic element of the sensor is made in the form of a shaped membrane, which is equipped with a power rod. On the membrane there are two bridges of foil tensoresistors, each is equipped with a rectangular insulating substrate, bridges are located in mutually perpendicular directions. Membrane rod rests against one of force-introducing hemispheres. Cylindrical support of the membrane rests on the second force-introducing hemisphere. Measured force is transmitted through the force-introducing hemisphere to the power rod, which deforms the membrane and the strain gauge bridges fixed on it. When voltage is supplied to inputs of bridges and its loading by force (weight) on output diagonals of bridges output signals are generated, which are proportional to measured force, which are supplied to two connectors located on opposite sides of the second hemisphere.

EFFECT: high accuracy and reliability of the sensor, as well as ease of manufacture.

3 cl, 5 dwg

Description

The invention relates to measuring technology, and specifically to sensors (D) for measuring weight and force.

A strain gauge force sensor (TSF) is known, containing an elastic element (UE) in the form of a membrane on which a strain gauge bridge (TP) is attached [1]. The disadvantages of such D are that they have significant nonlinearity and hysteresis errors caused by the tension of the middle surface of the membrane.

The closest in technical essence to the proposed invention is a TDS containing UE in the form of a profiled membrane [2]. For such D, the linearity of the characteristic is improved by leveling the deformation field of the membrane. Disadvantages include the difficulty of sticking TP onto curved membrane surfaces and poorly filtered errors from parasitic shear forces.

The objectives of the invention are to simplify the sticker and increase the accuracy of the location of the TP on the membrane, increase the accuracy and reliability of measurements due to the possibility of sticking two TP bridges and the inclusion in the design D of two force-receiving hemispheres and a force-transmitting rod that filter parasitic transverse forces, as well as by reducing temperature errors " zero" and sensitivity by manufacturing the main elements D from the same grade of steel.

The set goals are achieved by the fact that the UE is equipped with two TP bridges and a power rod, which rests on the first force-receiving hemisphere, and the cylindrical support of the elastic element rests on the second force-receiving hemisphere. In the support, to eliminate the effect on the accuracy of D of stretching the middle surface of the membrane, an elastic hinge is formed using two blind, annular, counter-directional grooves. And also by the fact that each bridge in the form of extended chains of sequentially located TP is fixed on a rectangular insulating substrate, the substrates are fixed on the flat surface of the membrane in mutually perpendicular directions, while the TP, precisely fixed on the substrate, when fixed to the membrane, are precisely located on it in zones with equal values of radial stresses of different signs, formed due to the calculated profile of the second side of the membrane. And also by the fact that the elastic element and two force-receiving hemispheres are made of the same grade of steel. In FIG. Figure 1 shows section D, where P is the measured force. In FIG. 2 - diagram of the arrangement of TP bridges on the membrane. In FIG. 3 - diagram of loading of a flat membrane with diameter D, constant thickness h const by force P, as well as a diagram of bending moments In FIG. 4 - loading diagram of a profiled membrane with a diameter D of variable thickness force P and diagram of bending moments In FIG. 5 - electrical diagram D, where R1, R2, R3, R4 are TP resistances in the bridge circuit, (1-3) - terminals for supplying supply voltage, (2-4) - terminals for recording the output signal.

Designations adopted in the figures: 1 - membrane UE; 2 - power rod; 3,4 - TP bridges; 5 - upper hemisphere radius 6 - lower hemisphere radius 7 - blind, circular, counter-directed grooves; 8 - substrates of two TP bridges; 9 - blind holes in the hemispheres on a turnkey basis for screwing them to the UE; 10 - sealing gaskets - seals; 11 - electrical connectors: out. 1, out. 2; 12 - adapter block for wiring leads from strain gauges and wires to connectors. The sensor operates as follows: when supply voltage is applied to the bridge diagonal (1-3) and the sensor is loaded with force P, an output signal proportional to the measured force is generated on the output diagonal (2-4).

The proposed design of the TDS makes it possible to increase the reliability and accuracy of measurements through the use of two bridges on the membrane and to simplify the precise sticking of TP in zones of equal mechanical stresses of different signs, as well as to reduce the temperature drift of the “zero” and temperature changes in sensitivity due to the manufacture of the main elements D from the same brand become.

Sources of information accepted by the author during the examination:

1. US Pat. No. 3095551 cl. 338-5, publ. 06.25.63.

2. US Pat. No. 3213400 Cl. 338-5, publ. date. 06.25.63.

Claims (3)

1. A strain gauge force sensor containing a membrane elastic element and a strain gauge bridge, characterized in that the elastic element is equipped with two strain gauge bridges and a force rod, which rests on the first force-receiving hemisphere, and the cylindrical support of the elastic element rests on the second force-receiving hemisphere; in the support, to eliminate the influence of stretching of the middle surface of the membrane, an elastic hinge is formed using two blind, annular, counter-directional grooves. 2. The strain gauge force sensor according to claim 1, characterized in that each bridge in the form of extended chains of sequential strain gauges is fixed on a rectangular insulating substrate, the substrates are fixed on the flat surface of the membrane in mutually perpendicular directions, while the strain gauges are precisely fixed on the substrate, at its fastening on the membrane are precisely located on it in zones with equal values of radial stresses of different signs, formed due to the calculated profile of the second side of the membrane. 3. The strain-resistive force sensor according to claim 1, characterized in that the membrane elastic element and two force-receiving hemispheres are made of the same grade of steel.

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