SU1416625A1 - Device for controlling electric drive of power shovel - Google Patents

Abstract

BACKGROUND OF THE INVENTION The invention relates to the control of electric drives of the mechanisms for lifting and heading of a single-bucket excavator. The goal is to increase the reliability of excavators under the complex effect of wind load, denial-. telny tp and speed of their change. For this, the device additionally contains a wind speed sensor 14, two adders (C) 8, 13, a converter (R) 15 analog-code, two analog keys 9, 10, an integrator 11 and a high-pass filter 16. With the first input C 8 is connected to the sensor 7 t-ry ambient air, with a second input C 8 and - the input of the functional P 12 through the integrator 11 is connected to the output of the key 9. The output of the key 10 through the filter 16 is connected to the first input of the second C 13, the second input of which is connected to the output L 12. Output C 8 is connected to the first inputs of the keys 9, 10, and output C 13 to the control input of the link 3 Neighboring connected to a current regulator 4. Since second inputs keys 9, 10 through 15 analog P-code sensor 14 is connected to the wind velocity. The C 8 coupled with the sensor 7 together with the key 9 and the integrator 11 makes it possible to take into account the thermal inertia of the metal structure (MK) and to change it in. time values of permissible loads on MJ as its t-ry changes. From the C 8 output, the signal is switched by the key. 10 is supplied to the filter 16. The key 10 is controlled by pulses P 15 connected to the sensor 14. The symmetric operation of the keys 9 and 10 allows the output of the filter 16 to select a signal proportional to the input voltage of the integrator P, which corresponds to the rate of change ry MK. 3 il. (L 05 & tsS 01

Description

1

1U

BACKGROUND OF THE INVENTION The invention relates to electric drive control systems for the mechanisms for lifting and heading a single-bucket excavator and. It is intended to limit the current of the core chain when excavators operate under extreme conditions at low temperatures down to minus 60 ° C.

The purpose of the invention is to improve the reliability of single-bucket excavators with the complex effect of wind load, negative temperatures and the speed of their change.

FIG. 1 shows a block diagram of the device; in fig. 2 is a functional diagram of the analog-code converter in FIG. 3 is a graph of load reduction versus level negative temperatures.

The device includes a main drive control system consisting of a series-connected controller 1, an EMF regulator 2 with a limiting link 3 in the feedback circuit, and a current regulator 4. The control system is connected to an electric power converter 5 with an engine 6 connected to it.

Air temperature sensor 7 is connected to the first input of the first totalizer 8 signals; the output of the first adder 8 signals connected to the first inputs of the first 9 and second 10 analog keys; the output of the first analog switch 9 is connected to the input of the integrator 1I; the output of the integrator 11 is connected to the second input of the first adder 8 of the signals and the input of a functional converter 12, the output of which is connected to the first input of the second sum of the 13 signals; the sensor 14 wind speed is connected to the input of the converter 15 analog-code; the output of the converter 15 analog-code is connected to the second inputs of the first 9 and second 10 analog keys; the output of the second analog key 10 is connected to the input of the filter 16 high frequencies; the output of the high-pass filter 16 is connected to the second input of the second cyi fMaTO pa 13 signals; the output of the second signal adder is connected to the input of link 3 of the limit.

With a complex effect on the metal structure of the excavator of extreme climatic conditions, the device operates as follows.

166252

At a low negative temperature and wind tension, the signal from the temperature sensor 7 is fed to the input of the sum-, mat 8, which, together with the analog key 9 and the integrator 11, allows to take into account the thermal inertia of the metal structure, which is described by the equation

ten

- DT uTg-,

(one)

where & t

temperature difference in the metalwork;

ТTd - the initial temperature difference; . temperature constant

metal construction time, and vary with time the magnitude of allowable loads on the metal structure as its temperature changes. Blocks 7-9 and I1 realize the dependence of CO and at the output of block 11 there is a signal proportional to the temperature of the inner layers of the metal structure.

The constant time Z depends on the wind speed V according to the formula

1 TO,

(TO

1 + V,

6

-).

(2)

where K, - at V;

I L1K

V - HC (m / s). 10 (m / s)

time constant at Vg, O.

The wind speed is measured by the wind speed sensor 14, and the analog-code converter 15 generates pulses arriving at the second input of the analog switch 9, the frequency f of which is determined by the dependence

45

R - t -4- V 17 DV

where f d, „c - the minimum frequency of pulses is 15 at Vg O; - the transmission coefficient of the 50-day wind speed.

The operation of the device 7-12, which implements the dependence (1) and (2) with the error S 10%, is determined by the following equation: 55

and,.

Cdt T in

t "(f

min Aw R

T p.

(3)

where k

D.T

.3141

sensor transmission coefficient; temperature; C - constant integration

integrator;

t J, is the pulse duration of the converter;

and y is the voltage at the output of the integrator,

Thus, the device allows us to consider when working excavators not only the level of negative temperature of the metal of the machine itself, but also the adverse effect of wind load.

From the output of the adder 8, the signal is switched by the analog key 10 and fed to the high-pass filter 16. The key 10 is controlled by the pulses of the converter 15. The symmetrical operation of the keys 9 and 10 allows the output of the filter 16 to produce a signal proportional to the input voltage of the integrator 11, which corresponds to the rate of change temperature of the metal excavator.

The signal If at the output of the filter 16 is associated with the output signal And the adder 8 expression

6625

where E is the modulus of normal elasticity; d is the linear expansion coefficient.

As follows from the expressions — the output-i signal of the Ecr of the filter 16 is proportional to the thermal stresses of the meta-structures (. This signal is fed to the second input of the adder 13.

The signal Hj, from the output of the integrator 11, is fed to the input of the functional converter 12, which, in accordance with the curve (Fig. 3), limits the load level of the drive, taking into account the magnitude of the signal AND. The output of the converter 12 is the voltage, the value of which is determined by the input signal AND ,. The temperature range up to minus 20 С block 13 realizes the dependence

and ,, „and, - and,

in the dangerous temperature range from minus 20 to 0 С the dependence is realized:

AND

BULL

 And, p - And

and and

(four)

The signal Hfl at the output of the integrator 11 is proportional to the temperature of the metalwork of the excavator and is associated with AND expression

-and

- with

dHu dt

(five)

dTv

dT

(6)

The temperature difference in the metal is proportional to the rate of temperature change.

 S g

(7)

and generates thermal stresses that increase the load on the metal structure and contribute to brittle fracture

ep ± 5 E ,,

(eight)

thirty

In the temperature range minus 40-50 ° C, the control device operates with the maximum limit, since

five

0

five

0

five

AND

V1

the accumulator becomes less than the value of the limiting voltage of the block 3 embedded in the circuit as recommended by the manufacturer. When the temperature reaches minus 50 ° C, the excavator is stopped in accordance with the manufacturer’s operating instructions.

The device allows you to differentiate automatically the magnitudes of the locking currents of the excavator's main drives, taking into account the extreme operating conditions.

Claims (1)

Invention Formula A control device for a single-bucket excavator, containing a control device connected through a parallel-connected EMF regulator and a limiting link to. a current controller connected to the electric drive, as well as an ambient temperature sensor and a functional converter, that is, in order to increase the reliability of the single With the complex effect of wind load, negative temperatures and speeds of their change, it additionally contains a wind speed sensor, two adders, a converter analog-code, two analog keys, an integrator and a high-frequency filter, and the ambient temperature sensor is connected to the first input of the first adder , the output of which is connected to the first inputs of analog switches, -, wind speed sensor through the transform + G55 0 118 25 The analog-code recipient is connected to the second inputs of analog switches, the output of the first analog switch is connected via an integrator to the second input of the first cy 1 mapper and to the input of a function converter, the output of the second analog switch is connected to the first input of a second adder via a high-frequency filter connected to the second input of the second adder, the output of which is connected to the control input of the limit link. + 155 -155 eight 0J Fm.2 4-5 -eight