RU2170820C2 - Method of automatic regulation of load of coal shearer cutting drive - Google Patents

Abstract

FIELD: automatic control of load of cutting drive of coal shearers by regulation of feed speed. SUBSTANCE: regulation is effected in two ways. For this purpose, setting of nominal current value is preset and current instantaneous vale consumed by shearer cutting drive is continuously measured. Average current is found. Current scattering values are additionally determined and average current value is compared with setting of nominal current value and speed of shearer feed is regulated to maintain their equality. Novelty consists in that current scattering value setting is present and compared with determined above current scattering value, and speed of shearer feed is additionally regulated by maintaining their equality. EFFECT: higher reliability of control system of shearer feed speed and stabilization of loading of shearer cutting electric motor. 2 dwg

Description

 The invention relates to a system for automatically controlling the process of coal extraction by combines and, in particular, is intended for automatic control of a feed drive of a coal combine.

 A known control method by means of a load regulator of the type "Uranus" (B. Ya. Starikov, V.L. Azarh, Z.M. Rabinovich. Asynchronous electric drive of shearers. - M .: Nedra, 1981), including setting the rated current and cut-off current of the cutting drive electric motor and continuous change in the instantaneous value of the consumed current.

This method has significant disadvantages:
1. Does not protect the motor from overheating;
2. It causes self-oscillations of the feedrate of the combine due to the low speed of the feedrate control system and the presence of significant non-linearities in the hydraulic part of the feed mechanism.

 A known method of controlling a mountain combine (RF patent N 2057931, MKl. E 21 C 35/24, published April 10, 1996), which provides control of the load of the cutting drive by changing the feed rate of the coal processor, including setting the rated current and cutoff current and continuous measurement of the instantaneous current I (p) of the mining machine cutting drive used to determine the effective current, which is compared with the set current, and maintain their equality by changing the feed rate of the combine, compare the instantaneous values I cutter current of a mining machine cutting drive with a given cutoff current and when the instantaneous current exceeds the cutoff current, the feed rate is instantly reduced.

 The disadvantage is the low reliability of control due to the lack of prediction of maximum loads, which led to the presence of the second control channel - cutoff.

Closest to the proposed invention is a method for automatically controlling the feed rate of coal combines (RF patent N 2066757, MKl. E 21 C 35/24). The method includes setting the nominal current setting, continuously measuring the instantaneous current value of the coal processor cutting engine and determining the average current, determining the current dispersion, comparing the average current with the rated current setting and adjusting the feed rate of the combine by maintaining their equality. By the value of the current dispersion, the standard deviation of the consumed current is determined, and the probable value of the maximum motor current I _{max is} determined from it. Compare I _max with the cut-off setting, set automatically as a function of the magnitude of the voltage at the motor terminals. If I _{max is} exceeded, the cutoff settings reduce the current setting.

 This method allows you to adjust the load of the cutting engine, but does not reflect its heating, which is undesirable for coal combines.

 The technical result of the invention is to increase the reliability of the automatic control system for the feed rate and stabilize the loads of the cutting machine of a coal combine by predicting the maximum loads in the cutting drive.

 The technical result is achieved in that in a method for automatically controlling the load of a cutting drive of coal combines by adjusting the feed rate, including setting the nominal current setting, continuous measurement of the instantaneous current value consumed by the cutting engine of the coal combine and determining the average current, determining the current dispersion, comparing the average current with the setting rated current and regulating the feed rate of the harvester by maintaining their equality, set the current dispersion setting, compare e e with current dispersion and additionally regulate the feed rate of the combine by maintaining their equality.

Где I(p) - мгновенное значение тока двигателя резания,
I_ср - средний ток,
k₁ - коэффициент передачи апериодического звена, определяемый необходимой чувствительностью системы управления,
Т - постоянная времени, которая должна быть в 10...20 раз больше времени затухания корреляционной функции графика потребляемого двигателем резания тока.To calculate the variance D ₁ can be applied the formula

Where I (p) is the instantaneous value of the current of the cutting motor,
I _cf - average current,
k ₁ - transfer coefficient of the aperiodic link, determined by the necessary sensitivity of the control system,
T is the time constant, which should be 10 ... 20 times the decay time of the correlation function of the graph of the current cutting consumed by the motor.

 The method is illustrated by drawings, where in FIG. 1 shows a block diagram of a device that can be used to implement the method, and FIG. 2 - the results of mathematical modeling of the system.

 In FIG. 1 shows a block diagram of a device. The device comprises, on the first channel, a current sensor 1, an aperiodic link 2 for averaging the current consumption value, and the second channel, a current sensor 1, an aperiodic link 2, an adder 3, a quadrator 4, an aperiodic link 5, a feed mechanism 7, a cutting motor 8 The outputs of both channels are connected by the first and second inputs of the elements to the dead zones of the adder 6.

 Aperiodic links 2 and 5 are made with a time constant T, which should be 10 ... 20 times the decay time of the correlation function of the graph of the current consumed by the motor cutting, which is T = (5 ... 10) seconds. The deadband in the first channel is equal to the set value of the average load current of the cutting motor. The deadband at the second input is equal to the permissible current dispersion of the cutting motor.

 Feedback signals are supplied to two inputs of adder 6, and a signal proportional to the specified feed rate of the coal processor is fed to the third input.

In FIG. 1 also shows the elements of a functional diagram of a coal processor:
K, K _m are the proportionality coefficients between, respectively, the feed rate V _p and the moment of resistance M _s (p) and the current of the cutting motor I (p) and the moment developed by the latter.

 All computing units are run on serial chips.

 The achievement of the task is confirmed by the results of mathematical modeling of the proposed system, shown in FIG. 2. Here the following notation occurs.

I is the instantaneous value of the load current,
I _cf - the average value of the load current,
(II _cf. ) ² - the square of the difference between the instantaneous and average load current,
D ₁ - dispersion of the load current.

The essence of the method is to use automatic control of the feed rate of the combine through two channels. During normal operation of the combine, the average current consumption of the cutting motor must not exceed the rated current. Automatic regulation consists in the fact that when the average current consumed exceeds the rated current, which corresponds to the setting in the form of a dead zone of the second input of the adder 6, negative feedback is activated, which affects the decrease in the feed rate. On the second channel, the dispersion D _{1 of the} consumed current is calculated on the circuit elements 1, 2, 3, 4, 5. When the dispersion exceeds its setting, determined by the dead zone of the first input of adder 6, negative feedback is activated, which affects the decrease in the feed rate to a value corresponding to a given dispersion value.

The automatic control system does not require on-site adjustment and is determined only by the parameters of the cutting motor and can be carried out at the factory of coal combines. In addition, the regulation of the dispersion of the consumed current allows you to predict the magnitude of the current loads and limit them to a value that does not cause the motor to tip over, and also predict the heating of the cutting motor, since the dispersion of the consumed current is
D = (I _e ² -I _cf ² ) = ² (k _f ² -1)
where I _e - equivalent (heating) current,
I _cf - average current consumption,
k _f - coefficient of the form of the current graph, showing how many times the heating current of the motor exceeds the average current.

 Using the proposed method will improve the reliability of the drive of the combine, since to a greater extent compared with the prototype meets the random nature of the load of the coal processor - coal seam system.

Claims (1)

 A method of automatically controlling the load of a drive for cutting coal combines by adjusting the feed rate, including setting the nominal current setpoint, continuously measuring the consumed cutting engine of the coal processor for instantaneous current values and determining the average current, determining the current dispersion, comparing the average current with the nominal current setting and adjusting the feed rate of the combine by maintaining their equality, characterized in that they set the current dispersion setting, compare it with the current dispersion and add They carefully adjust the feed rate of the combine by maintaining their equality.

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