GB2168410A

GB2168410A - Method and system of controlling the operation of a coal working machine

Info

Publication number: GB2168410A
Application number: GB08531051A
Authority: GB
Inventors: Wojciech Skoczynski; Antoni Kandzia; Wojciech Halota; Stanislaw Orchel; Zygmunt Jaromin
Original assignee: POLMAG; Komag Inc
Current assignee: POLMAG; WD Media LLC
Priority date: 1984-12-17
Filing date: 1985-12-17
Publication date: 1986-06-18
Also published as: GB8531052D0; DE3544272C2; PL251046A1; DE3544272A1; HUT43372A; CN85109637A; GB8531051D0; PL147277B1

Abstract

A method and system for controlling the operation of a working machine in the mining industry, and which can be employed in working coal by the longwall system, solves the problem of selecting the optimum operating parameters of the working machine with regard to working power consumption, coal cuttability and workability, and yield of coarse coal depending on the properties of the seam being worked. The method consists in predetermining the most advantageous value of the load of the drive unit and of the food rate of the working machine and then controlling these parameters during the working so that after at least one of the controlled parameters changes, the supporting capacity of a section of the hydraulic support and the feed rate is corrected to suit the existing load. According to this invention, the drive unit 16 of a working machine 17 is connected to an analyser 18 in the system which analyser is in turn connected to pressure relief valves 15 and prop displacement sensors 19 of the individual sections of the hydraulic support. <IMAGE>

Description

SPECIFICATION Method and system of controlling the operation of a coal working machine The present invention relates to a method and system for controlling the operation of a coal working machine, particularly one used in working coal by the longwall system.

A method of changing the cuttability and/or workability of a seam, particularly of coal, is known from Polish Patent Specification No. 121,273, involving adjusting the pressure of the hydraulic support against the roof. It is also known that the workability and cuttability of coal, when a seam is being worked mechanically, depends on the stresses in the seam.

The above-mentioned stresses also have great influence on the power consumption of the coal working operation and on the yield of coarse coal.

The stresses operating in the longwall face in the region being worked are decisive here. The stresses are in principle set up by roof pressure, undergoing changes under the influence of the action of the hydraulic support on the roof.

The most advantageous parameters are obtained only when the stresses set up in the region of the seam being worked are correct. An increase or decrease in these stresses will cause the working parameters to be impaired. In a known method, stresses in a seam are changed by changing the supporting capacity of the hydraulic support by changing the pressure of the space below each of the prop pistons.

A device for changing the cuttability and/or workability of a seam, particularly of a coal seam, is known from Polish Patent Specification No.

121,273 and comprises a hydraulic support of any type controlled by a set of valves and connected to supply and drain manifolds. The spaces below the pistons of the props of the hydraulic supports are connected to a drain manifold via a pressure relief valve. By suitably resetting the pressure relief valve, the hydraulic support can be made to exert a definite force on the roof so that the stresses in the seam will assume the most advantageous value from the point of view of the workability and cuttability of the coal.

The aim of this present invention has been to provide a method of selecting the operating parameters, depending on the properties of the seam, and a means of synchronising the change in the supporting capacity of the hydraulic support with the operation of the coal working machine.

According to one aspect of the present invention, there is provided a method of controlling the operation of a coal working machine by varying the supporting capacity of the hydraulic support, comprising presetting the optimum load of the coal working machine drive unit and the rate of feed of the coal working machine along a longwall, then.

controlling the actual values of these parameters during the operation of the coal working machine by comparing them with the preset values and, when at least one of the controlled parameters has deviated from the preset value, changing the support capacity of at least one section of the hydrualic support in the region corresponding to the operating region of the coal working machine, whereafter the feed rate of the coal working machine along the wall is corrected relative to the existing load of the drive unit and, after the passage of the coal working machine, the pressure of the rack on the sections of the hydraulic support is checked by measuring the extent of sink of the props, and the supporting capacity is increased in dependence on the sink determined in at least one section of the hydraulic support.

If at least one of the controlled parameters has deviated from the predetermined optimum value, the supporting capacity of at least one section of the hydraulic support in the region corresponding to the operating region of the coal working machine will change. After this operation has been performed, the feed rate of the coal working machine along the longwall is corrected relative to the existing load of the drive unit. After the coal working machine has passed, the pressure of the rocks on the sections of the hydraulic support is checked by measuring the sink of the props, and the supporting capacity of at least one section of the hydraulic support is increased accordingly.

A second aspect of the present invention provides a system for controlling the operation of a coal working machine and comprising a hydraulic support provided with a set of valves, the space under the pistons of the hydraulic props being connected via a pressure relief valve to a drain mains, the drive unit of the coal working machine being connected to an analyser connected in turn to pressure relief valves and prop displacement sensors of the individual sections of the hydraulic support. The advantage of the design according to this present invention is the possibility of determining the most advantageous operating parameters of the coal working machine by freely selecting the stresses along a longwall in the region to be worked, depending on the character of the seam.

In order that the present invention may more readily be understood the following description of one embodiment is given merely by way of example with reference to the accompanying drawing representing the control system for the operation of the coal working machine along a longwall.

At the longwall 1, section 2 of the hydraulic support are expanded and located transversely to longwall face 3. The hydraulic assemblies of section 2 are supplied with a hydraulic fluid from a unit via a supply mains 4. From section 2, the hydraulic fluid is drained back to the unit via a drain mains 5. The two mains 4, 5 are connected to a distributor valve 6 whose outlets are connected, via hoses 7, 8, to a valve block 9 which comprises a non-return valve and an overflow valve.

The space 10 under the piston of a vertical hydraulic prop 11 is connected via a hose 12 to the valve block 9 whose other outlet is connected via a hose 13 to the space 14 above the piston of the hydraulic prop 11. In this drawing the props are shown as horizontal in order to simplify the illustration.

A pressure relief valve 15 is installed between the drain mains 5 and the hose 12 supplying the space 10 under the piston.

On the other hand, the drive unit 16 of the coal working machine 17 is connected to an analyser 18 which is connected to the pressure relief valves 15 of the individual section 2 of the hydraulic support.

Also displacement sensors 19 are located on the hydraulic props 11 of the section 2 and are all connected to the analyser 18.

In the neutral position of the distributor valve 6, the two hoses 7, 8 are both connected to the drain mains 5 and the supply to the hydraulic prop 11 is cut off.

Prior to extending a section 2 of the hydraulic support, the pressure relief valves 15 are set to a pressure not lower than that prevailing in the system. When initially extending the hydraulic support, the hydraulic fluid is supplied from the unit, via the supply mains 4, to the respective distributor valve 6 which has been preset to a position enabling the hydraulic fluid to flow via the valve block 9, to the space 10 under the piston of the associated hydraulic prop 11. At the same time, the space 14 above the piston of that hydraulic prop 11 is connected to the drain mains 5, via the hose 13, the valve block 9 and the distributor valve 6.

After the support has been extended, the pressure of the roof against the hydraulic support causes the pressure in the space 10 under the piston to increase. The total closure of the space 10 under the piston causes the pressure in that space 10 to be capable of increasing to a value set by the overflow valve of the valve block 9. This overflow valve has been set to the maximum pressure permitted in the system.

The supporting capacity of the hydraulic support is changed by setting pressure relief valve 15. The pressure set on pressure relief valve 15 is lower than that set on the overflow valve of the valve block 9.

After a trial traversing operation of the coal working machine illustrated, the optimum torque resistance of the driving unit 16 and the rate of feed of the coal working machine 17 along the longwall 3 are determined with regard to the power consumption of coal working, the coal workability and cuttability, and the yield of coarse coal. The parameters thus determined are fed to the analyser 18 whose functions can be fulfilled by a microprocessor.

When a seam is being worked, the coal working machine moves along the longwall face from left to right. The analyser 18 controls and records the operating parameters of the coal working machine 17, and particularly the torque on the driving unit 16 and the feed rate of the coal working machine 17 along the longwall 3, by comparing each of those parameters with the predetermined value. As soon as the torque of the driving unit 16 has exceeded the preset value, the analyser 18 resets the pressure relief valves 15 of the section 2 located in the particular region being worked.

The supporting capacity of the section 2 of the hydraulic support is thus decreased and, therefore the stresses in the working region of the seam are changed. The analyser 18 checks the torque loading on the drive unit of the coal working machine 17. If the torque resistance has been decreased, the analyser 18 causes the feed rate of the coal working machine to be increased, and if no change in the torque has occurred the analyser 18 causes the feed rate of the coal working machine 17 to be decreased. After the passage of the coal working machine 17 beyond a section 2, the sensors 19 located on the piston ends of the hydraulic props 11 measure the sink, ie. contraction, of the hydraulic props 11 caused by the pressure of the roof.

The above result is transmitted to the analyser 18, if the predetermined limit, depending on the character of the rock, has been exceeded. The analyser 18 then resets the pressure relief valves 15 so that the supporting capacity of the section 2 of the hydraulic support will be increased.

Claims

1. A method of controlling the operation of a coal working machine by varying the supporting capacity of the hydraulic support, comprising presetting the optimum load of the coal working machine drive unit and the rate of feed of the coal working machine along a longwall, then controlling the actual values of these parameters during the operation of the coal working machine by comparing them with the preset values and, when at least one of the controlled parameters has deviated from the preset value, changing, the support capacity of at least one section of the hydraulic support in the region corresponding to the operating region of the coal working machine, whereafter the feed rate of the coal working machine along the wall is corrected relative to the existing load of the drive unit and, after the passage of the coal working machine, the pressure of the rack on the sections of the hydraulic support is checked by measuring the extent of sink of the props, and the supporting capacity is increased in dependence on the sink determined in at least one section of the hydraulic support.

2. A system for controlling the operation of a coal working machine and comprising a hydraulic support provided with a set of valves, the space under the pistons of the hydraulic props being connected via a pressure relief valve to a drain mains, the drive unit of the coal working machine being connected to an analyser connected in turn to pressure relief valves and prop displacement sensors of the individual sections of the hydraulic support.

3. A method of controlling the operation of a coal working machine, substantially as hereinbefore described with reference to the accompanying drawing.

4. A system for controlling the operation of a coal working machine, substantially as hereinbefore described with reference to, and as illustrated in, the accompanying drawing.