GB2205346A - Control system for mine roof support - Google Patents

Abstract

A control system for a mine roof support is provided, the control system having fluid distribution means 10, 11, at least one closed centre valve 18d attached thereto, at least two pilot pistons 57, 58, each operable by fluid from a fluid source to act on a valve closure member 39 of the valve and hence open the valve, and selection associated with said valve to select one of said pistons 57, 58 to open said valve, and hence direct fluid from the same fluid pressure source to perform an operation within the sequence of operations of the mine roof support. A novel control valve and rotary valve are also disclosed. <IMAGE>

Description

Control Systems and Valves Therefor The invention relates to control systems and valves therefor. The invention is particularly concerned with control systems for hydraulic mine roof supports.

Mine roof supports are required to perform a number of specific duties in underground mine workings. The primary duty is to support the mine roof during the mineral winning cycle and there may be up to 200 individual mine roof support units arranged in a side by side relationship. In addition to supporting the mine roof, each support provides an abutment to which other mining equipment may be attached and moved relative thereto.

In most modern roof supports the functions of each roof support are executed by means of hydraulic jacks which may be selectively operated by hydraulic or electro-hydraulic control devices. The functions referred to may be divided into two types, those requiring a large fluid supply for rapid operation and those where smaller hydraulic jacks may be used and consequently the fluid supply requirements are comparatively less for similar operating speeds.

The high fluid supply jack requirements may include the supporting jacks and the advancing jacks for each individual roof support assembly, whilst the low fluid supply jack requirements may include hydraulic jacks for operating face sprags, extension bars and side spacing functions. Functions controlled by electric signals may also be identified with high fluid supply requirements. Since low power sources must be used underground for safety reasons, the solenoid or motorised valves which can be operated from a low power source do not usually have a large flow capacity.

However these valves can act as pilot valves to operate other large flow main valves.

In practice, it has been difficult to design a single hydraulic valve which will meet both high and low demand requirements when due consideration is given to the operating pressures and conventionally, high fluid demand functions are controlled via pilot operated control valves. Thus at least two control valves have been used, and often two fluid supply lines for a single operation of a support function, namely the main supply line and the pilot supply line.

It is also known to have a further fluid supply on mine faces where two working pressures are required, for example where a coal winning machine known as a coal plough is used. A main working pressure may for example be of the order of 1,000 p.s.i., whereas the pressure required by pilot valves or by a coal plough may be of the order of 300 p.s.i.

It is therefore an object of the invention to provide a control system enabling the operation of an installation of mine roof supports with a minimum number of fluid pressure supply lines and a minimum number of control devices for the selection of the functions, preferably with a single return line serving the roof support installation.

Accordingly, the invention provides a control system for a mine roof support, the control system having fluid distribution means, at least one closed centre valve attached thereto, at least two pilot pistons each operable by fluid from a fluid source to act on a valve closure member of the valve and hence open the valve, and selection means associated with said valve to select one of said pistons to open said valve, and hence direct fluid from the same fluid pressure source to perform an operation within the sequence of operations of the support.

The control system may comprise a combination of modular elements meeting the operational requirements for a roof support installation.

The control system may enable adjacent control or bank control of the roof supports from a pre-determined end computer location, for example, from another support or from a face/ The control system may comprise a control module comprising a power valve manifold to which is attached a pilot manifold and the selection device.

The control module may include electro-hydraulically operated closed centre pilot valves.

The control module may include hydraulically operated closed centre pilot valves.

The control module may include pressure switches and electrical connections.

The control module may have a plurality of closed centre valves, for example from 3 to 7 valves, to suit the particular needs of a roof support.

The selection device may be arranged to select from a plurality of different functions, for example up to 12 different functions, either on a host support or an adjacent support.

Latch means may be provided so that after an operator has selected a particular function, the function will continue even if the operator leaves the selection device.

On at least some functions, a "dead man" control feature may be provided, so that if the operator leaves the selection device, these functions stop automatically.

There may be a plurality of control modules, each for location on a separate mine roof support, one of said pilot pistons of each module being connected to the selection means on the same module and the other pilot piston of the said module being connection to the selection means of another module such that in use, one pilot piston of a module can be operated from the host support while the other pilot piston of the module can be operated from a remote support.

A closed centrevalveimay have more than 2 pilot pistons, all the pilot pistons of a module abutting each other prior to selection of only one pilot piston.

A control module may be provided with a solenoid or motorised valve arranged to be opened by means of an electrical signal to allow pressurised fluid to act on one of the pilot pistons of the closed centre valve.

The other pilot piston of the closed centre valve may be actuated by pressurised fluid selected from the selection means of a different control module arranged at a different location, for example on an adjacent roof support.

control There may be a full hydraulic/system in which a hydraulic signal for one pilot piston can be generated at a host support, whilst a hydraulic signal for the other piston can be generated at a remote or adjacent support.

Preferably the closed centre valve of each module will have a measure of lost motion between the valve closure member of the valve and at least one of the pilot pistons.

When neither pilot piston is energised the valve closure member may be urged against one valve seat under the influence of resilient means to cut off pressurised fluid flow and at the same time connect a service support of the valve to exhaust.

The selection means of a control module may be arrangable to select fluid pressure for the operation of the associated closed centre valve, by directing fluid to one of the pilot valves, or it may be used to select a functional hydraulic actuator or a hydraulic jack by a direct connection which does not pass through a closed centre valve, thus avoiding the need for a separate main fluid supply line and a/pPilot pressure fluid supply line.

The control system according to the invention may be arranged to control the following functions, which are given by way of example : (a) An advancing jack, for connection between a conveyor and a mine roof support, to advance the conveyor and subsequently advance the roof support to a new position adjacent to the conveyor, may be controlled via a closed centre hydraulically operated provision of the pilot fluid for the VaLve, the/opening thevave being either manually or electrically initiated. While the advancing jack is active, other functions of the roof support need not be inhibited and can take place at the same time.

After advance of the conveyor, a pilot operated nonreturn valve may be used as part of a control system to prevent the conveyor being moved back towards the roof support under the influence of a passing mining machine or the influence of back pressure caused by the advance of an adjacent support. The locking function provided by the non-return valve may be cancelled on a subsequent operation in which the roof support is advanced adjacent to the conveyor.

(b) A latching function may be provided on the conveyor advance function. This feature allows an electro-hydraulic valve controlling the operation to have electrical power removed again after only a brief energisatnon. However once energised, the valve is latched in the open position so that the operation is sustained until the operation is completed or deliberately cancelled. Such cancellation may take place automatically when the roof support is lowered and/or advanced.

(c) When the advancing jack is used to advance the roof support adjacent to the conveyor, a trip and advance sequence may be adopted, whereby the roof support is automatically advanced upon its being released from its roof supporting condition. This sequence may be electrically or hydraulically initiated. By using this sequence the superstructure or canopy of a roof support may be maintained in close proximity to the mine roof during the advance of the support.

(d) Although it is unusual to retract a conveyor relative to a roof support, it is an advantage, for servicing and like operations, to have such a facility available within a roof control system. During such an exercise the trip or latch facilities may be rendered inoperable, and all the interconnections may be simply arranged in a single manifold or similar device such as a ported gasket plate.

(e) Ancillary circuits may be provided within the control system to service equipment often regarded as optional, the fitment thereof often being determined by mining considerations rather than as an enhancement of the roof support operation.

Examples of this type of equipment and the way in which the control system of the operation may operate are as follows (i) a face sprag is a device adapted to exert a force against a newly exposed mine face, after the passage of the cutting machine, and is used to retain the wall of mineral in position until the next cutting cycle takes place. To achieve the placement and retention of the sprag in its operative position, two closed centre pilot operated valves may be added to a main power manifold, one for setting the sprag in which a jack is usually extended, and a further similar valve for parking the sprag in which the sprag is usually retracted. The jack may be locked hydraulically whenever a selection operation is discontinued.A further safety feature may be built in in that the sprag may be left in its set position against the mineral bearing face when the roof support is advanced, and in such case the sprag will be parked when the roof support is reset to the mine roof when advanced to its new position.

(ii) to accommodate undulations in a mine roof, many mine roof supports are provided with articulated cantilever roof engaging structures at their leading ends, and such articulation is usually controlled by means of a vertically or horizontally acting hydraulic jack. This jack is normally released and/or reset to the mine roof with compatible operations taking place at the same time, although the cantilever structure is held in its working position by a pilot operated nonreturn valve and the locked circuit is protected by an overload or yield valve. A separate valve and circuit may be provided for the purpose of lowering the cantilever relative to the main roof engaging canopy.

According to a second aspect of the invention, a is provided fluid control valve /òur selectively controlling fluid from a pressure fluid supply to a service port and from said service port to a return port, said valve having a valve closure member normally biased to separate said fluid supply from said service port and connect said service port to said return port, and at least two fluid operable means which are selectively operable to act upon said valve closure member to isolate said service port from said return port prior to connecting the pressure fluid supply to said service port.

The valve closure member may have a fluid conduit to allow fluid to flow between the service port and the return port.

One of said fluid operable means may have a closure part which, upon operation of either fluid operable means serves to close said fluid conduit in the valve closure member.

The fluid operable means having the closure part and said valve closure member may be urged apart prior to the selection of the fluid operated means.

According to a third aspect of the invention, a rotary selection valve is provided, for the control of pressurised fluid, there being means to prevent the pressurised fluid from creating a frictional resistance to the turning of the rotor.

This may be achieved by isolation means which prevent the pressurised fluid from acting on the rotor.

Fluid passageways may'be provided to prevent a fluid lock in the valve which would otherwise inhibit the operation of the valve.

By way of example, a specific embodiment of the invention will now be described, with reference to the accompanying drawings in this : Figure 1 illustrates diagrammatically an embodiment of control system according to the invention; Figure 2 is a plan view of the control module of the system; Figure 3 is a front view of the control module; Figure 4 is a side view of the control module; Figure 5 is a cross-sectional view of a closed centre valve of the system; and Figure 6 is a cross-sectional view of part of a selection device of the system.

The system illustrated diagrammatically in Figure 1 consists of a control module comprising a selection device 10, a pilot manifold 11 and a power manifold 12.

The control module is extremely versatile and in this example is shown connected to various components of a mine roof support, namely two support legs 13 and 14, an advancing ram 15 and a compensating ram 16. The legs 13 and 14 and the advancing ram 15, require a substantial flow of pressurised fluid, and they are therefore connected to the power manifold 12 as will be described in more detail below.

The compensating ram 16 requires a lower level of flow, and so the compensating ram can be operated from the pilot manifold 11.

The selection device comprises a manual control handle 17 which has 12 different positions to control the flow of fluid to fluid passages within the pilot manifold 11, as will be described in more detail below.

The pilot manifold 11 simply directs fluid from the control module 10 to the power manifold 12 and to ancillary equipment such as the compensating ram 16.

The power manifold 12 comprises a plurality of closed centre valves 18a, 18b, 18c, and 18d. It also comprises a plurality of electrically operated valves l9a, 19b,19c, and 19d.

The closed centre valves 1Ba and 18b are used to control the advancing ram 15 via lines 20 and 21. The closed centre valves 18c and 18d are used to control the legs 13 and 14 via lines 22 and 23.

Each of the closed centre valves is connected by lines 24 and 25 to a common supply line 26 and a common return line 27. A non-return valve 28 is provided between the lines 24 and 27, and an isolating valve 29 is provided between the lines 25 and 26, making it possible to disconnect the support from the common supply line, should it be necessary to remove or replace the support.

The lines 24 and 25 also supply fluid to a main valve 30 of the control module.

The main control valve 30 is shown in more detail in Figure 6. It has a central inlet port 31 and 12 service ports, one of which, 32, is shown in the figure.

The valve has a rotor 33 which can be turned by handle 17. The handle 17 comprises a lever pivoted at 34 and having an extension 35 for engagement in any one of a plurality of notches 36 provided by the castellated rotor housing 37.

In the inlet port 31, there is a valve seat 38 which.

is normally closed by a valve member 39. Abutting the valve member is a hollow spindle 40 and a push rod 41 engages against this spindle. When the handle 17 is turned until the extension 35 is in register with a selected notch 36 to select a particular function, then the handle 17 is raised, the push rod 41 and spindle 40 move the valve 39 off its seat 38 and pressurised fluid is able to flow through the passage 42, through a radial passage 43 and through a passage 44 in the rotor 33 to the selected output port 32. Sealing around the passage 42 is provided by a spring loaded pad 45 and when the valve 39 is closed, there is no fluid pressure acting on the rotor 33 or any part thereof, so that between operations, the rotor 33 can readily be manually rotated to select a desired position. Sealing around the passage 44 is provided by a further spring loaded sealing pad 46.A thrust race 47 is also provided to further reduce- the effort in turning the rotor.

However, because no force in the vertical direction, as viewed in the Figure, is applied by the pressurised fluid to the rotor during the selection of a desired radial position, the thrust race 55 may be replaced by a nylon, delrin or like low friction material thrust washer.

During operation of the valve all ports other than the selected port 32 are connected to exhaust via the rotor chamber 48.

After the valve has been closed again, the passage 42 is vented to exhaust since the hollow spindle 40 can lift off the tapered upper end of the valve number 39, and a passage is then formed between the passage 42, the centre of the hollow spindle 40, and radial passages 48 and 49.

The valve 30 is shown diagrammatically in Figure 1, and it will be appreciated the the handle 17 and associated parts provide a dead man control valve 50 such that if the handle 17 is released, it returns to the position shown in Figure 6, valve number 39 closes, and the selected port is isolated from the supply.

It will also be seen from Figure 1 that the various ports of the valve 30 are connected some to the compensating ram 16, via lines 51 and 52, and some to first pilot ports of the closed centre valves 18a to 18d, one such port being referenced 53 by way of example on the valve 18d. Each closed centre valve also has a second pilot port, that for valve 18d being referenced 54, and this second port is connected to an associated electrical valve.

The valve 18d is shown in more detail in Figure 5. It should be appreciated however that all the closed centre valves are identical.

The valve body 55 contains a passage 56 in which are mounted two pilot pistons 57 and 58. Port 54 communicates with the upper end of pilot piston 57 and port 53 communicates with the upper end of pilot piston 58.

The valve also has a feed port 59, a return port 60 and a service port 61. Adjacent to the service port 61, there is a sleeve member 62 in which there is slidably mounted a valve member 63. The valve member 63 has a valve face 64 which, as shown in the Figure is normally urged by a spring 65 into contact with a valve seat 66 thus isolating the service port 61 from the feed port 59. The service port 61 is connected to the return port 60 via radial holes 67 in the hollow upper part of the valve member 63.

If fluid pressure is applied to the port 53, the pilot piston 58 is urged downwardly against the action of the spring 68 until a chamfered portion 69 of the pilot piston seals the hollow upper part of the valve member 63, thus closing off the centre of the valve from the return line 60 before the central part of the valve is connected to the feed port 59.

Further movement of the pilot piston 58 moves the valve member 63 off its seat and allows pressurised fluid to flow from the feed port 59 to the service port 61.

When pressure to the port 63 is removed, the valve returns to the position shown in Figure 5. It will be seen that the valve can be operated equally well by the application of fluid pressure to the port 54 instead of to the port 53. In this case the pilot piston 57 applies pressure to the pilot piston 58 and moves the pilot piston 58 as before.

The service port 61 is designed to be connected to any desired service via a staple type locking connection 70.

Turning now to the connections to the legs 13 and 14, and the compensating ram 16, in more detail, it will be seen that the legs 13 and 14 are fitted with conventional pilot operated release valves 71 and 72.

Between the release valves 71, 72 and the legs 13, 14, there are pressure overload valves 73 and 74, and also pressure gauges 75 and 76, The valves 71 and 72 normally trap fluid under pressure within the legs, unless fluid is applied in the direction to lower the legs. Line 23 is connected to the service port of closed centre valve 18d, so that if that valve is opened, fluid flows through the line 23 to raise the legs.

To lower the legs 13 and 14, pressurised fluid is supplied by means of the closed centre valve 18c to the line 22.

The lines communicating with the compensating ram 16 are provided with pressure relief valves 77 and 78.

There are also non-return valves 79 and 80.

The 12 possible positions of the valve 30 are referenced la to 12a.

If position la is selected, then the valve 30 supplies fluid to one of the pilot ports of close centre valve 18c and the legs 13 and 14 are lowered.

If the position 2a is selected, one of the pilot pistons of valve 18b is actuated and fluid is supplied to line 21 to advance the support.

If position 3a is selected, valve 18d is opened and the legs 13 and 14 are raised.

If position 4a is selected, valve 18a is opened and fluid is supplied to line 20 to advance a conveyor attached to the mine roof support.

If position 8a is selected, fluid is supplied via the pilot manifold 11 without the need for an intermediate pilot piston to extend the compensating ram 16.

If position lla is selected, then pressurised fluid is directed to the retract side of the same ram 16.

In other words, the ram 16 responds directly to the fluid flow from the pilot manifold and not indirectly through a closed centre valve since the high flow capacity associated with a closed centre valve is not required.

One operation of the selection valve 30 will now be described in detail, using the selection of position la as an example.

Immediately prior to selection of the position, pressurised fluid is present in line 25, via isolating valve 29, and is thus available at the inlet port 31 of the selection valve 30 and at the feed port 37 of the closed centre valve 18c. The handle 17 is turned until the extension 35 is in register with the notch associated with position la, and the handle is then lifted, forcing the push rod 41 and spindle 40 to move the valve member 39 of its valve seat 38. Thus pressurised fluid can flow from the inlet port 31 to the passages 42, 43 and 44, to reach the relevant outlet port 32. Pressurised fluid from the port 32 now acts as a pilot feed to port 53 of the closed centre valve 18c. This in turn pressurises the chamber between the two pilot pistons 57 and 58 and the lower piston 58 is urged into sealing engagements with the valve member 63.This then caps off any leak between the service port 61 and the return port 60. Continued movement of the pilot piston 58 moves the valve member 63 off its seat 66 and pressurised fluid passes from the feed port 59 to the service port 61. This opens the non-return valves 71 and 72 and allows fluid to be discharged from the legs through the line 22.

Each of the electric valves 19a to 19d is provided with a feed and return port, as can be seen from Figure 1, connected to the main lines 26 and 27 by lines 24 and 25. Each of the electric valves also has a service port, which, as can be seen from Figure 1, is connected to the second pilot port of an associated closed centre valve. For example the service of the electric valve 19d is connected to the pilot port 54 of closed centre valve 18d. This makes it possible for the closed centre valves to be actuated electrically, rather than manually, if desired. Signals are transmitted to the electric valves by means of a control cable 81 which is connected to a multi-terminal output jack 83.

To further assist in electrical control, the leg 14 and the advancing ram 15 are connected by lines 84 and 85 to pressure responsive electric switches 86 and 87. Thus, for example, various functions may be initiated electrically when the pressure in the advancing ram and/or in one of the legs indicates that a particular stage in the advancing or raising sequence has been reached. Electrical signals may be transmitted to the electrical valves from the host support on which the control module is mounted, or from an adjacent support, or from a remote support, as desired.

The invention is not restricted to the details of the foregoing example. For instance there need not be four groups of valves. There may be three, six, or any desired number.

As can be seen from Figure 4, the control module has two hose connections 88 and 89. If the module is required to communication hydraulically with a plurality of other items, e.g., adjacent supports, a multi core hose coupling may be provided.

Claims (20)

1. A control system for a mine roof support, the control system having fluid distribution means, at least one closed centre valve attached thereto, at least two pilot pistons each operable by fluid from a fluid source to act on a valve closure member of the valve and hence open the valve, and selection means associated with said valve, to select one of said pistons to open said valve and hence direct fluid from the same fluid pressure source to perform an operation within the sequence of operations of the support.

2. A control system as claimed in Claim 1, comprising a combination of modular elements.

3. A control system as claimed in Claim 2, having a control module comprising a power valve manifold to which is attached a pilot manifold and the selection means.

4. A control system as claimed in Claim 3, in which the control module comprises electro-hydraulically operated closed centre pilot valves.

5. A control system as claimed in Claim 3, in which the control module comprises hydraulically operated closed centre pilot valves.

6. A control system as claimed in any one of Claims 3 to 5 in which the control module includes pressure switches and electrical connections.

7. A control system as claimed in any one of Claims 3 to 6, in which there is a plurality of control modules, each for location on a separate mine roof support, a first pilot piston of each module being connected to the selection means on the same module and a second pilot piston of the said module being arranged for connection to the selection means of another module such that in use, one pilot piston of a module can be operated from a host support while the other pilot piston of the module can be operated from a remote support.

8. A control system as claimed in any one of the preceding Claims, comprising a closed centre valve having more than two pilot pistons, all the pilot pistons of a module abutting each other prior to selection of only one pilot piston.

9. A control system as claimed in Claim 8, having a control module provided with a solenoid or motorised valve arranged to be opened by means of an electrical signal to allow pressurised fluid to act on one of the pilot pistons of the closed centre valve.

10. A control system as claimed in Claim 9, in which a second pilot piston of the closed centre valve may be actuated by pressurised fluid selected from the selection means of a different control module arranged at a different location, for example on an adjacent roof support.

11. A fluid control valve for selectively controlling fluid from a pressure fluid supply to e service port and from said service port to a return port, said valve comprising a valve closure member normally biased to separate said fluid supply from said service port and connect said service port to said return port, and at least two fluid operable means which are selectively operable to act upon said valve closure member to isolate said service port from said return port prior to connecting the pressure fluid supply to said service port.

12. A fluid control valve as claimed in Claim 11, in which the valve closure member has a fluid conduit to allow fluid to flow between the service port and the return port.

13. A fluid control valve as claimed in Claim 11 or Claim 12, in which one of said fluid operable means has a closure part which, upon operation of either fluid operable means serves to close said fluid conduit in the valve closure member.

14. A fluid control valve as claimed in Claim 13, in which the fluid operable means having the closure part and said valve closure member may be urged apart prior to the selection of the fluid operated means.

15. A rotary selection valve for the control of pressurised fluid, comprising a rotor and means to prevent the pressurised fluid from creating a frictional resistance to the turning of the rotor.

16. A rotary selection valve as claimed in Claim 15, having isolation means which prevent the pressurised fluid from acting on the rotor.

17. A rotary selection valve as claimed in Claim 15 or Claim 16, in which fluid passageways are provided to prevent a fluid lock in the valve which would otherwise inhibit the operation of the valve.

18. A control system constructed and arranged substantially as herein described, with reference to the accompanying drawings.

19. A fluid control valve constructed and arranged substantially as herein described, with reference to the accompanying drawings.

20. A rotary selection valve constructed and arranged substantially as herein described, with reference to the accompanying drawings.