SU1747960A1 - Dynamometer - Google Patents

Abstract

The invention relates to load measuring technology. The goal is to increase gear ratio and accuracy. Device; .. -:;. ;; 2 contains a force element, made in the form of a lever 1 suspended on force-measuring elements 2 and 3, which ensures their preliminary expansion. the force is applied to the lever 1, the load cell 2 is load-s, and the load cell 3 is unloaded, which makes it possible to realize a pavement measuring circuit with four active tensor strasses. The selected stiffness ratio of the force-measuring elements 2.3, depending on the distance between their points of attachment on the lever 1 and the distance from the point of application of force to the point of attachment of the nearest force-measuring element, provides the maximum signal. 1 il. о С с с с 2 SI ю о о

Description

The invention relates to load measuring technique and can be used in measuring static forces and masses. A load measuring device is known in which a load measuring element in the form of a strip with unresponsive strain gauges attached to measuring springs, made in the form of two symmetrically arranged trapezoid brackets rigidly connected by open large bases.

However, in this device, the force-measuring element works only for stretching, which prevents the implementation of a bridge circuit with four active tensor-eistor, as well as to obtain a strictly linear characteristic in the low-load version of the sensor.

The closest in the proposed measuring device, which uses two compression sensors, preloaded with axial force due to pressing to the power receiving plate using studs and working in a differential circuit with additional load-unloading of sensors with the application of the measured force to the power receiving device.

The device has the ability to implement a bridge circuit with four active strain gauges.

 However, in the known device, the preload force of the sensors and the power plate must be at least 50% of the measured force, which limits the possibility of obtaining high transmission ratios. The design of the device is difficult to create high-precision, low-speed sensors.

The purpose of the invention is to increase the transmission coefficient and measurement accuracy.

The goal is achieved in that the force-sensing element in the force-measuring device is made in the form of a lever, one end of which is suspended from the body on the measuring and measuring elements, at the other end of which there is a point of application of force, the center of gravity of the lever arm is located stiffness of the force-measuring elements are selected from the ratio

Sd C2

1 +

where C.1 and Ca, respectively, the rigidity of the force-bearing elements;

L is the distance between the attachment points of the load cells on the lever;

I is the distance from the point of application of the force to the point of attachment of the nearest force gauge.

The drawing shows the construction of the measuring device.

The input element 1 is suspended on the force-measuring elements 2 and 3 to the housing 4. From the external environment, the working area of the strain resistors is sealed with a membrane 5.

The principle of operation of the measuring device is as follows.

Suspended, for example, on load-bearing elements 2 and 3, lever 1 of mass m causes the preliminary stretching of load-bearing element 2 by a force of Рг mg

i

and load cell 3 force

I

Ps mg -g-.

When a measured force P is applied to the lever, force-measuring element 2 is reloaded by

35

AFfc-P-ktL,

(one)

and the force-measuring element 3 is unloaded by

40

DRZ-R "-,

(2)

those. Under the action of the measured load by the force, the measuring elements are incremented by deformations of different signs, which makes it possible to realize a bridge circuit with four active strain gauges.

To obtain the maximum signal and improve the metrological characteristics according to the nonlinearity criterion, it is necessary that the increments of relative deformations of the strain gauges be equal in absolute value:

I egy 1 i ez i. (3)

Since the force-bearing elements work for stretching,

(four)

where c | - rigidity i-ro load cell.

Taking into account expressions (1), (2) and (4), condition (3) can be represented as

-CL-14-L Sz 1 + G

The advantage of the proposed device in comparison with the known one is an increase in the transmission coefficient and accuracy of force measurement.

Claims (1)

Claims of Invention A force-measuring device comprising two preloaded load cells and a force-receiving element placed in a housing with a protective membrane, characterized in that, in order to increase the coefficient five 0 transmission and accuracy of measurement, the power receiving element is designed as a lever, one end of which is suspended from the body on the load cells, at the other end of which there is a point of application of force, the center of gravity of the load arm is chosen from the ratio with - oh. L C2I where Ct and C2 are, respectively, the rigidity of the force-measuring elements; L is the distance between the attachment points of the load cells on the lever; I is the distance from the point of application of force to the point of attachment of the nearest force measuring element.