GB2094864A

GB2094864A - Hydraulic control systems for mineral mining installations

Info

Publication number: GB2094864A
Application number: GB8207237A
Authority: GB
Original assignee: Gewerkschaft Eisenhutte Westfalia GmbH
Current assignee: Gewerkschaft Eisenhutte Westfalia GmbH
Priority date: 1981-03-17
Filing date: 1982-03-12
Publication date: 1982-09-22
Also published as: ES8303604A1; JPS57161298A; FR2502241A1; AU8124482A; ZA821609B; DE3110220A1; FR2502241B1; GB2094864B; DE3110220C2; AU544025B2; ES510539A0

Abstract

An electro-hydraulic control system for controlling a mineral mining installation employs a valve device 36 in the vicinity of the main pump supplying the pressure fluid. This valve device 36 is capable of creating a short circuit directly between the main fluid feed and return lines P, R to disable the entire installation. Emergency switches 44 are distributed along the working and are accessible to personnel. The operation of any one of these switches 44 serves to actuate the valve device 36 to create the short circuit condition. <IMAGE>

Description

SPECIFICATION Improvements in hydraulic control systems for mineral mining installations The present invention relates in general to mineral mining installations and, more particularly, to hydraulic and electro-hydraulic control systems which serve to selectively connect consumer appliances, such as props, shifting rams and the like, to pressure fluid feed and return lines.

Control systems providing local, remote and/or automatic control functions of various kinds are known in the art. Typically, support units arranged along the working are provided with individual hydraulic control valve devices which connect the consumer appliances associated with the unit to a common pressure fluid feed line and to a common pressure fluid return line. These common lines extend along the working and connect with a pump and fluid reservoir at one end of the working or in an adjacent roadway. Where remote control is to be effected a control station connects with electromagnetic valve devices, for example, associated with the hydraulic control valve devices via one or more control lines.In modern systems, the support units are provided with individual assemblies or valve blocks comprising the various valve devices and each assembly is adapted to enable direct manual control, sequential group control in alternate directions, conveyor shifting and similar functions to be carried out as desired.

Electronic programmable control circuits in conjunction with position and other monitoring equipment makes it possible to utilize the control system in a fully adaptive manner to change operations to cope with prevailing conditions either through control signals initiated remotely at the control station or locally at the mineral face. In the event of failure or break down or in dangerous situations it is possible to override the remote or automatic control functions by operating the individual valve blocks manually and thereby to interrupt the control operation which is taking place. Nevertheless situations can arise where such manual control is not sufficient to remedy the situation immediately. Indeed, when an automatic sequence is interrupted it is possible for hunting to occur.This is because it is not possible to reduce the pressure in the consumer appliances rapidly enough and there is some delay before the system responds to the manual override.

A general object of the present invention is to provide an improved control system.

In accordance with the present invention, additional valve means is connected between the main fluid feed or supply line and the main fluid return line. A plurality of switches are distributed along the working and each switch is capable of actuating the additional valve means to connect the feed and return lines together to create a hydraulic short circuit to disable the appliances in the working. These measure provide a simple yet reliable safety facility making it possible in an emergency to interrupt the operation of the appliances with very little delay avoiding the hunting hitherto encountered.

The valve means which establishes the short circuit condition is preferably located near to the main pump and associated fluid storage vessel and the valve means can be mounted on the pump itself. Thus, the short circuit can be established at the source of the hydraulic energy. By creating the short circuit condition at the source of hydraulic energy the main feed line along the working will experience a practically instantaneous reduction in pressure to disable the consumer appliances.

Since most, if not all, of the appliances will employ shut-off or non-return valves they will become effectively isolated from the supply and will lock in the position they adopted when the short circuit condition was created.

The switches which actuate the valve means can be connected to the valve means via one common line the continuity of which is interrupted by the operation of any one of the switches. The switches can be located in positions readily accessible to the mine personnel and one such switch can be allocated to each support unit along the working. In one preferred embodiment of the invention, the switches are connected in series to pass an energizing electrical current to the valve means to bias the latter into a normal operating state where there is no direct connection between the supply and return lines. Any switch can then be operated to establish an open circuit to disable the energizing current to permit the valve means to change automatically to a state wherein the short circuit is established. Failure of the electrical supply would also result in the short circuit condition.

Where the switches are electrical switches the valve means may be composed of a hydraulic valve device connected between the fluid lines and an electromagnetic control valve device which is connected through a control line or cable to the switches. The electromagnetic control valve device then serves to control the operation of the hydraulic valve device according to whether the switches are open or closed as is desired.

Conveniently, the electromagnetic control valve device would be held in one state by the energizing current passed along the control line or cable against the restoring force of a spring. In this one state the electromagnetic valve device would provide a path for pressure fluid to act an operating piston of the hydraulic valve device to bias this device into a state where the supply and return lines are not connected together. The operating piston of the hydraulic valve device can then also be opposed by spring force. In the event of a fault or emergency the electromagnetic valve device would then automatically change state to cause the hydraulic valve device to change state likewise automatically to establish the hydraulic short short circuit.

The control system may also employ a low pressure fluid supply line which is used for control purposes to operate valve devices pertaining to the consumer appliances or which is used to drive some of these appliances or which is used to drive some of these appliances. In this case, it is desirable to provide further valve means similar to the additional valve means which can connect this low pressure line to the return line in an emergency. This further valve means can be identical to the additional valve means and operated by the same emergency switches. Both the short-circuit valve means can be structurally combined as a unitary assembly.

The invention may be understood more readily, and various other aspects and features of the invention may become apparent, and consideration of the foliowing description.

An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawing which is a block schematic diagram depicting part of a hydraulic control system constructed in accordance with the invention.

For the sake of clarity, the accompanying drawing represents only part of a complete control system in association with just one roof support unit of a longwall mining installation. This single unit can take a variety of forms but is exemplified as having four hydraulic props: namely two front props 1, 2 and two rear props 3, 4: relative to a mineral face (not shown). The props 1 to 4 are mounted in known manner between a floor-sill structure and a roof-engaging structure. The structures are single or multipart components and the props 1 to 4 are each preferably articulated to the floor-sill structure and the roof-engaging structure.

A doubel-acting ram 6 is mounted between the unit and a conveyor (not shown) and serves to effect relative movement therebetween and to advance the conveyor and the unit in incremental steps as a mineral winning process progresses in known manner.

Typically, the roof-engaging structure of the unit may be provided with a forward bar extension - the so-called advance lining -- which is conveniently pivotably mounted to the main roof engaging structure supported directly by the props 1 to 4. A double-acting piston and cylinder unit 5 serves to adjust the forward roof bar extension between operative and inoperative positions.

Finally the support unit is provided with additional double-acting piston cylinder units 7, 8 which serve to adjust the positions of gap-sealing covers at the sides of the roof-engaging structure by extending or retracting these covers laterally outwardly of the unit.

The support unit thus has a number of hydraulic-energy consuming appliances 1 to 8. As is known a plurality of such support units each with their own hydraulic appliances would be arranged adjacent with one another along the mine working and the gap-sealing covers at the sides of the roof-engaging structures of the units would then engage on one another.

A hydraulic control system pertaining to the installation has a high-pressure fluid feed line P, a high-pressure fluid return line R, a low-pressure fluid feed line ND and a low-pressure fluid return line Rst. The lines P, R and NDR serve to drive the hydraulic appliances of each support unit under the control of various devices which selectively connect the various appliances to these lines. The lines P, R, ND, Rst can take the form of pipes or conduits extending along the working and connected to one or more pumps and a storage vessel conveniently located at the end region of the working or in an adjacent roadwork gallery.

Each support unit of the installation has a block or housing incorporating a number of individual hydraulic control valve devices 9-1 3 as well as electromagnetically operated control devices 14-1 9 and pressure relief valves 20-23. The valve devices 9-13 have similar ports connected via lines 24,25 to the lines PR as shown.

Likewise, the valve devices 14-1 9 have similar ports connected via the lines 24, 27 to the lines P, Rst as shown. The valve device 1 3 has another port connected by a line 26 to the line ND. The device 9 has further ports connected via lines 28, 29 to the pressure chambers of the front props 1, 2. The device 10 has further ports connected via lines 30, 31 to the pressure chambers of the rear props 3, 4. The devices 9, 10 can adopt one of three operative states as represented in the drawing to connect the chambers of the props to the lines P or R thereby to extend or retract the props 1 to 4, or to lock the props 1 to 4. The device 11 has further ports connected via lines 32, 33 to the working chambers of the unit 5.The device 11 can also adopt one of three operative states as represented in the drawing to connect the working chambers of the unit 5 to the line P or R thereby to extend or retract the unit 5 and adjust the operative position of the roof-bar extension.

The device 12 also has further ports connected via lines 34, 35 to the working chambers of the units 7,8. The device 12 can adopt one of three operative states as presented in the drawing to connect the working chambers of the unit 7, 8 to the lines P, R thereby to adjust the position of the gap-sealing covers. The device 1 3 has further ports connected via lines 50, 51 to the working chambers of the shifting ram 6. The device 13 can also adopt one of three operative states represented in the drawing to connect the working chambers of the ram 6 to the lines PR or ND, R to extend or retract the ram 6 to shift the entire unit or the conveyor towards the mineral face.

The valve devices 9-1 3 are adapted to be operated both hydraulically and manually to change their operative states. The hydraulic operation of the devices 9-1 3 is effected by way of the devices 14-1 9. The devices 14-1 9 have further ports connected to operating pistons or the like of the devices 9-1 3 as represented by the dotted lines in the drawing. The devices 14-1 9 are actuated by electrical signals, i.e.

electromagnetically in a manner not shown in the drawing but known per se, and are preferably linked together to form a cascade arrangement providing sequential control.

A valve device 36 is preferably located at the end zone of the working or in the adjacent roadway gallery near the pump. This valve device 36 has ports connected to the main pressure line P and the main return line R via lines 37, 38, 39 as shown. The valve device 36 is capable of adopting one of two operative states as represented in the drawing and in one state (that shown in the drawing) the device 36 provides a hydraulic short circuit connecting the line P directly to the line R.

The valve device 36 is itself controlled with a control valve device 40 which takes the form of an electromagnetic valve device similar to the valve devices 14 :0 1 9 provided on the support units.

The valve device 40 has ports connected via the lines 37, 38 with the return line R and the high pressure line P and a port connected via a line 41 to a control piston of the device 36. A non-return valve 42 is incorporated in the line connecting the valve device 40 to the return line R. The device 40 is capable of adopting one of two operative states as presented in the drawing. The device 40 is operated by way of an electrical signal in a similar manner to the valve devices 1 4-1 9. An electrical control line leading to the valve device 40 is designated by reference numeral 43. Conveniently this electrical control line extends along the mine working and a number of isolating switches 44 are distributed over the length of the mine working and connected serially in the control line 43.

Preferably, the switches 44 are allocated individually to each support unit and are mounted in a readily accessible position, such as on the floor-sill structure of the unit or on the valve control block or housing. The valve device 40 is arranged to be held in a normal working state by means of a steady current passing along the control line 43. In this normal state, the line 41 is connected via the line 38 to the main pressure line P. As a result, the valve device 36 is held by the pressure in the line 41, which opposes the restoring force of a spring, in its normal operative state where the lines 38, 39 are disconnected from one another. In an emergency condition, an operator can immediately disable the hydraulic control system by actuating any one of the emergency switches 44 to disconnect the electrical supply from the valve device 40.In this event, the device 40 changes state under the restoring force of a spring and the line 41 is connected to the return line R. A spring restoring force in the valve device 36 then changes the state of this valve device 36 to the position shown in the drawing in which the lines 38, 39 are connected together to thereby short circuit the hydraulic fluid supply. It is apparent that in the event of a failure of the electrical supply system a similar short circuit operation would occur. When the valve device 36 is operated in this manner to short circuit the hydraulic supply, the line P extending along the mine working loses pressure and all the hydraulic consuming appliances will become non-operative.

In the same locality as the devices 36, 40 another valve device 36' with a control valve device 45 is also connected in a similar manner to the devices 36, 40.

The valve device 36' has ports connected to the main return line R and to the control pressure line ND as shown. The valve device 36' is capable of adopting one of two operative states as represented in the drawing and in one state (that shown in the drawing) the device 36' provides a hydraulic short circuit connecting the line ND directly to the line R. The associated control valve device 45 is again an electromagnetic valve device. The valve device 45 has ports connected to the main pressure line P and to the return line R.

The latter connection is established via a line 47 in which a non-return valve is provided. The valve device 45 has a port connected via a line 46 to a control piston of the device 36'. The device 45 is capable of adopting one of two operative states as represented in the drawing. The device 45 is operated by the electrical control line 43. The device 45 is held in a normal working state by the electrical current passing along the control line 43.

In this normal state, the line 47 is connected to the pressure line P. The valve device 36' is held by the pressure in the line P, which opposes the restoring force of a spring, in its normal operative state where the lines ND and R are disconnected from one another when any one of the switches 44 is actuated to disconnect the electrical supply from the valve device 40 the valve device 45 is similarly operated change state under the restoring force of a spring and the line 47 is connected to the return line R. A spring restoring force in the valve device 36' then changes the state of the valve device 36' to the position shown in the drawing in which the line ND is connected to the return line R. This inhibits the control devices and appliances along the mine working from operating. Preferably the valve devices 36, 36' and their control devices 40, 45 are combined to form one or more assemblies as indicated by the chain dotted line 48, 49.

Claims

1. A control system comprising pressure fluid supply and return lines and valve devices for selectively connecting the lines to hydraulic energy consumer appliances of a mineral mining installation in an underground mine working wherein additional valve means is connected between the supply and return lines and a plurality of switches are distributed along the working and each switch is capable of actuating the valve means to connect the supply line directly to the return line to create a hydraulic short circuit to disable the appliances.

2. A system according to claim 1, wherein the switches are connected in a control line and interrupt the continuity of the control line to actuate the valve means.

3. A system according to claim 1, wherein the switches are electrical switches.

4. A system according to claim 3, wherein the switches are connected in series with a control line providing electrical energy to the additional valve means, the operation of any one of the switches or the failure of the electrical supply serving to actuate the additional valve means to establish the short circuit condition.

5. A system according to claim 4, wherein the additional valve means comprises an electromagnetic valve device connected to said control line and a hydraulic valve device connected to the supply line and return lines and controlled by the electromagnetic valve device.

6. A system according to claim 5, wherein the electromagnetic valve device of the additional valve means is held in one state by energizing current passed along the control line against the restoring force of a spring and provides a path for pressure fluid to act on an operating piston of the associated hydraulic valve device against the restoring force of a spring to bias this device into a state where the supply and return lines are not connected together.

7. A system according to any one of claims 1 to 6, and further comprising another fluid supply line for supplying fluid at a lower pressure than that of the first-mentioned supply line and further valve means connected between the other fluid supply line and the return line and also actuated by said switches to connect the other supply line directly to the return line.

8. A system according to claim 7, when appended to claim 4, wherein the further valve means comprises an electromagnetic valve device connected to said control line and a hydraulic vavie device connected to the other supply and return lines and controlled by the electromagnetic valve device.

9. A system according to claim 8, wherein the electromagnetic valve device of the further valve means is held in one state by energizing current passed along the control line against the restoring force of a spring and provides a path for pressure fluid to act on an operating piston of the associated hydraulic valve device against the restoring force of a spring to bias the device into a state where the other supply and the return lines are not connected together.

10. A system according to claim 7, 8 or 9, wherein the further valve means is combined with the additional valve means to form a common assembly.

11. A system according to any one of claims 1 to 10 wherein the switches are mounted on individual support units of the installation.

12. A system according to any one of claims 1 to 11, wherein the additional valve means and/or the further valve means is, or are, mounted on a pump unit supplying the pressure fluid to said supply line or lines.

13. A control system substantially as described with reference to and as illustrated in the accompanying drawing.