SU756216A1 - Method and apparatus for weighing loads under dynamic conditions - Google Patents

Description

The invention relates to weighing equipment and can be used when weighing goods moved by cranes, when weighing goods on floating vehicles (ships, barges, etc.). _five

There are known methods and devices for weighing goods under dynamic conditions, in which the weighing error decreases due to the effect of inertial forces on a load due to the presence of a primary and secondary channel of power converters with 10 unknown and known loads for extracting signals, which determine the mass of an unknown load [1. ].

The closest to the invention by the technical essence is a method of weighing a cargo oscillation conditions at Ko ^'5 torus use channels of the main and additional tenzorezistornyh silopreobrazovateley from which additional balanced to zero static to dynamic allocation of interference of _two superimposed test load thereon and a device containing a power source of bridge power converters of the main and additional channels [2].

2

The disadvantage of this method is the relatively low accuracy and long duration of measurement.

The aim of the invention is to improve the accuracy and speed of weighing.

The goal is achieved by the fact that the dynamic disturbance voltage from the additional power converter is summed up with the supply voltage of both power converters in antiphase of the dynamic interference in the channel of the main power converter.

A device for implementing the method is equipped with a scaling node, the input of which is connected with the output diagonal of the additional power converter, and the output is connected in series with the power source of the power converters.

The drawing shows a diagram of the device.

The main tensoresistance silopreobrazovatel 1 is located on the crane hook 2 with attached to it the weighed load of 3 _x mass m. The additional strain gauge power converter 4, which is rigidly connected to the power transducers 1, is loaded with a control weight 5. This power transducer with a control weight of

756216

t l is balanced to zero in statics for the possibility of highlighting the voltage of the noise V .ι in terms of the movement of goods. The output voltage of the power converter 1 Uh is measured by the measuring device 6. To supply the power converters 1 and 4, the power source 7 with the voltage Е _{о is used} . The main and additional power converters are characterized by strain-transfer coefficients K _x and, respectively.

The method of weighing goods in dynamic conditions and the operation of the device implementing this method is as follows.

When lifting (lowering and other movements), weighed 3 and control 5 loads experience the same dynamic effects, as a result of which voltages arise at the outputs of the power converters

ν _χ = EK «-t _x (d + a), (,)

ν ₀ = Е-К ₈ с-т _о- а, (2.)

where £ is the acceleration of gravity; a is the acceleration characterizing the dynamic effect;

E is the supply voltage acting directly on the power converters.

Since the additional power converter 4 is balanced to zero in statics, there is no static component of voltage in voltage V ₀ .

The voltage from the output of the power converter 4 ν ₀ is fed to the input of the scaling node 8, having a Kum transmission coefficient, which to a certain extent reflects the reciprocal of the strain-transfer coefficient. Consequently, the voltage at the output of the scaling node is

Uum = U ₀ -Kum = E-Kum-K ^ -gpo-a.

This voltage (Uum) is summed with the voltage of the power source E _o so that the change in the total voltage E acting directly on the power converters 1 and 4 is obtained with a phase that is opposite in sign to the phase of the dynamic effect of interference on the main power converter,

E - E $ - Uum = E o - E-Kum-Ku t is?

or

1+ cuM’C ^ e.'HLo'D '’

The opposite of the phase signs means that with a positive sign, the acceleration and the supply voltage at the power converters decreases, and with a negative sign, it increases.

If in (1) to substitute (3), then we get the voltage at the output of the power converter 1

V - P,. Κκ, τηχ a (1 + -g) ______

^x 1 + Qom. (four)

By setting the scaling node's gain value to

Qom = - „

(Qom depends on the specific type of additional power converter and the magnitude of the mass of the control load), from expression (4) we get

ν _χ = Eo-K ^ m ^ e

Consequently, the output voltage ν _χ , coming to the input of the measuring device 6, does not contain a dynamic disturbance for any point in time. This not only improves the accuracy, but also the speed of weighing, which can be done during the lifting (lowering) of the load.

Claims (2)

Claim 1. The method of cargo weighing in dynamic conditions, in which the channels of the main and additional strain gauge power converters are used, of which the additional is balanced to zero in statics to isolate dynamic interference from the control weight imposed on it, characterized in that in order to increase the accuracy and speed of weighing , the voltage of the dynamic disturbance from the additional power converter is summed up with the supply voltage of both power converters in antiphase of the dynamic disturbance in the fundamental channel power converter. 2. A device for implementing the method of π. 1, containing a power source of bridge power converters of the main and additional channels, characterized in that it is provided with a scaling node, the input of which is connected to the output diagonal of the additional power converters, and the output is connected in series with the power supply of the power converters.