SU1597615A1 - Magnetoelastic dynamometer - Google Patents

Abstract

The invention relates to load measuring technique and allows to improve the measurement accuracy of a magneto-resistant load measuring device. The force measuring device contains two magnetoelastic converters 1 and 11, the magnetizing windings of which are connected in parallel and connected to the power supply unit 7. Under the action of the measured force F in the measuring windings 18 and 24, the voltages U ₂ and U ₁ appear, respectively. The voltage U ₂ through the measuring rectifier 2 and the divider 4 is fed to one of the inputs of the adder 5. In the divider 4, the voltage is multiplied by an amount equal to 0.5 K, where КъU ₁ / U ₂ . The voltage through the measuring rectifier 3 is fed to another input of the adder 5. As a result, the voltage at the output of the adder is proportional to the measured force, and its value is determined from the expression U = U ₁ - 0.4 KU ₂ . 2 Il.

Description

The invention relates to a load measuring technique and can be used in devices intended for the automatic weighing of railway cars, automobiles, to automate the work of dosers and t

The purpose of the invention is povapenie accuracy by reducing the error of magnetic hysteresis and TV t

Fig. 1 shows an electrical circuit diagram of a magnetoelastic force-measuring device; on figv2 - magnetoelastic converters

The magnetoelastic force-measuring device (figOO contains two magnetoelastic transducers 1 and 1, measuring rectifiers 2 and 3, voltage divider 4, summator 5, digital measuring device 6 and power supply unit 7,

Magnetoelastic transducers (FGV2) have a core 8 that can measure the measured force F in the form of a plate pack of magnetostrictive material, in which eight through holes 9–16 are made for winding two magnetoelastic transducers

The converter 1, located in the upper part of the core 8, has a magnetizing winding 17 in openings 9 and 12, a signal winding 18 in openings 10 and 11 and four additional windings 19-22, located in one of the above four holes of the core The converter 1о1, pa: located in the lower part of the core, has only two windings: a magnetizer 23 in the holes 13 and 16 and a signal 24 in the holes 14 and 15,

The magnetizing windings 17 and 23 under W1CW to block 7 power. The signal winding 18 is connected to the input of the measuring rectifier 2, and the second signal winding 24 is connected to the input of the measuring rectifier. 3, The rectifier outputs, one through a voltage divider 4, the other directly, are connected to an accumulator 5, realizing the subtraction function, and the output of the adder is connected to the input of a digital measuring device 6o. and according to and closed on

d

five

0

5 o

lp

50

five

five

154

short. Similarly, windings 2 and 22 are included,

The principle of operation of magnetoelastic transducers is as follows.

Flowing through the magnetizing windings 17 and 23, the alternating currents create magnetic currents, closing around the holes in which these windings are located. With a measured force F 0 and in the absence of anisotropy of the magnetic properties of the core in mutually perpendicular directions, the magnetic fluxes are not coupled with the signal windings 18 and 24 and the voltage at the terminals of the latter is zero. Under the action of the measured force F, applied to the core 8, the magnetic resistances of the vertical passages in the core between the winding holes increase, the magnetic flux is redistributed in the plane of the plate and a part of it is coupled to the signal winding. Voltages on the signal windings 18 and 24 produce voltages depending on

SSh1y fo

The magnetizing windings 17 and 23 have an equal number of turns. Each of the additional windings occupies no more than 20% of the area of the winding hole. At the same time, additional resistance is introduced into the magnetic circuit of the upper converter, and magnetic resistance is introduced, exceeding 2-3 times that which this circuit has when opening additional windings.

The magnetic circuit of the magnetoelastic transducer is non-linear and has a bridge structure with sensitive elements and in the form of sections of the magnetic conductor forming the shoulders of the bridge. As the non-linearity of such a circuit grows, the inverter’s error decreases,

In the core of electrical steel with a magnetic induction between the holes for the magnetizing MOT1SH, equal to 1.5 T or more, short circuit of the additional windings linearis: JT magnetic circuit and increases the relative error of the magnetoelastic transducer by approximately two

.raza,

It is used in a magnetoelastic force-measuring device, in

. the basis of which is supposed to be

five

two magnetic-elastic converters with a common core, one of which has a linear magnetic circuit, and the second is non-linear,

The load device implements the calculation of the output value and of the following equation:

and and - 0.5 Ki.

(1) to

de u: | - output voltage of the magneto-elastic converter without additional windings (voltage of the winding 24)

Uj is the output voltage of a magneto-elastic converter with additional windings (voltage 8); K is the average ratio of U to 11 found in graduation 20 in the range or in a predetermined part of the measurement range. since

25

TO

and 1 WedUf

about -

and

wed

and

(2)

and, and - average values of U ,, U1с 2

  in the range or in

this part of the measurement range 30, and and, - 0.5 K U2CiQ, 5 and,.

at graduation.

and. and,

working measurement

and,. and g +,;

Uj. Ujr + l,.

(3)

where L and nd are the absolute errors,

contained in the working measurement in the output. voltages U. and and, respectively.

Substituting (3) in (1) receive

and and, - 0.5 K L, - 0.5 K / 3i.

(four)

It is required to show that the difference in absolute errors

/ 3, - 0.5 Kl, entering into (4), is approximately equal to

but

15976156

to zero. Lp of this specified difference, taking into account the value of the coefficient K from (2), is converted to

to

s

0

five

0

five

0

five

0

five

And dr 0,5 and,.

The relative error j / U converter with a linearized magnetic circuit (with additional windings), which is twice the relative error / U of the second converter, being multiplied by half of the output voltage of the latter, i.e. 0.5 U, it will give the same error A, TaKiiM way

L, 0.5 K –l aO,

and the output value U of the device as a whole does not depend on the errors of the magnetoelastic transducers.

Therefore, when the working measurement in the output value (4) does not contain the error of the unit of magnetoelastic transducers 1, more precisely, the error contained in the output value is many times smaller compared to l, or j.

The device works as follows.

The measured force acts on the core 8 of the magnetoelastic transducers I and Ul, the output voltages U and and which from the terminals of the windings 24 and 18, respectively, are fed to the inputs of the rectifiers 3 and 2a. The voltage acting at the output of the voltage capacitor 2 and in the divider 4 is multiplied by an amount equal to -0.5K and is fed to the input of the adder 5, to the other input of which voltage U is fed from the output of the rectifier 3, In the adder, in accordance with by formula (1), Uj is subtracted from 0.5 K Uj and the voltage U is fed to the input of the measuring device 6, -C from which the measurement results are read or in a digital code are transmitted to the recording devices.

Formula a-of shade

A magnetoelastic force-measuring device containing two magnetoelastic transducers arranged one above the other, made in the form of a common core of electrical steel plates, mutually perpendicular magnetizing and signaling

Claims (1)

Claim Magnetoelastic force measuring device containing 55 OTHER FRIENDS on top of each other two magnetoelastic transducers made in the form of a common core from plates of electrical steel, the mutually perpendicular magnetizing and signal windings of each of the transducers are located in four through holes, the axes of which are perpendicular to the plane of the plates the four corners of a square whose diagonals intersect with the axis of symmetry of the plate and the direction of action of the measured force, the meter rectifiers in the circuits of the signal ed windings, the magnetization winding power supply unit, an adder, to the inputs of which are connected the signal winding circuits and a secondary measuring device connected to the output of the sum-editor, characterized in that, in order to increase accuracy by reducing the error from the mag -. filament hysteresis and temperature. it is additionally equipped with a voltage divider and four additional windings located in four holes together with the magnetizing and signal windings of one of the transducers, each of which covers a portion of the core between two adjacent holes, and additional windings located in parallel planes are interconnected sequentially and short-circuited ,but. the signal winding circuit of the magnetoelastic transducer with additional windings is connected to the adder input through a voltage divider.