US3521455A - Mining conveyor control means - Google Patents

Description

July 21, 1970 -F. TOWN MINING CONVEYOR CONTROL MEANS Original FiIed May 22, 196'? 3 Sheets-Sheet l July 21, 1970 F. TOWN 3,521,455

MINING CONVEYOR CONTROL MEANS Original Filed May 22', 1967 3 Sheets-$heet 2 FTl Q g L? t. l i a \n K :5 m I )/N L- UH July 21, 1970 F. TOWN 3,521,455

' MINING CONVEYOR CONTROL-MEANS Original Filed May 22, 1967 5 Sheets-$heet 5 United States Patent.

3,521,455 MINING CONVEYOR CONTROL MEANS Frank Town, Burton Joyce, England, assignor to W. E. & F. Dobson Limited Original application May 22, 1967, Ser. No. 640,280. Divided and this application Nov. 22, 1968, Ser. No. 778,177 Claims priority, application Great Britain, May 25, 1966, 23,301/66 Int. Cl. E21d 15/44 US. Cl. 61-45 4 Claims ABSTRACT OF THE DiSCLOSURE A mine roof support system having at least one hydraulic prop and an advance hydraulic jack connected with a conveyor for advancing the latter, the system including a hydraulic circuit connected to a pressurised fluid supply, a main valve being provided in the circuit and being operable to connect the supply on the one hand to extend the prop and on the other hand to retract both the prop and the hydraulic jack, the latter being connected to a pilot valve operable to extend the advance hydraulic jack for advancing the conveyor, the pilot valve having a fluid supply inlet and outlet and a fluid exhaust port, and including valve means movable between first and second positions wherein the outlet is respectively connected to the inlet and the exhaust port for extension and retraction of the advance hydraulic jack respectively, the pilot valve also having piston means actua'ble by a hydraulic pulse to act on a part of the valve means to move the latter to the first position, the valve means being so constructed that fluid flow through the pilot valve from the inlet to the outlet acts on said part of the valve means to hold the valve means in the first position; means also being provided to move the valve means back to the second position against the action of said fluid flow.

This application is a division of co-pending application Ser. No. 640,280 filed May 22, 1967, for Mine Roof Support Systems.

This invention is for improvements in or relating to hydraulic mine roof support systems of the type comprising a row of supports each having at least one hydraulic prop connected by an advancing hydraulic jack to a conveyor, the props being capable of hydraulic extension into roof supporting condition in which the advancing jacks can be hydraulically extended, a group at a time, to advance the conveyor with a snaking action, and also capable of hydraulic contraction into release condition in which the advancing jacks can be contracted one after another to advance the supports progressively. For this control it is known to have a main hydraulic control valve for each support and which is arranged by pilot fluid operation to direct pressure fluid to the annulus ends of the props for their release, also to the annulus ends of the advancing jacks for advancing the supports, and further to the piston ends of the props for re-setting them to the roof. Control to advancement of the advancing jacks is by pilot fluid operation of a latch valve for each advancing jack to direct pressure fluid to the piston ends of these jacks, in groups, for advancing the conveyor with its snaking action. This is followed by further operation of the main valves to again release the props and so on for repeat operation.

Since the snaking action of the conveyor entails movement of each section of it in turn from an inclined attitude to a straight attitude, this occupies a period of time during which it is known to hold on the pilot pressure to the latch valves of the group thereof until the conveyor section is fully advanced. One disadvantage of this is that during said period the pilot system is not available for any other use, another disadvantage is that in the event of the pilot signals being provided by electrical means, these electrical means can be a source of danger by being live for undesirably long periods, and a further disadvantage is that following the time of removing the pilot signals from the latch valves and before the props are operated to release, there is possibility of undesirable movement of the conveyor relative to the supports.

An object of the invention is to provide a mine roof system of the type referred to in such improved manner that said disadvantages are avoided.

The invention provides a mine roof support system comprising a mine roof support, at least one hydraulic prop in said support, a conveyor, an advancing hydraulic jack connected between said support and said conveyor, a main hydraulic control valve in said support, an auxiliary pilot-fiuid-operable hydraulic valve in said support, pressure and exhaust valve members in said auxiliary valve and which are pilot-fluid-operable in one direction for opening the auxiliary valve to a main pressure fluid feed, passage means in said auxiliary valve associated with the pressure and exhaust valve members and adapted for guiding the main pressure fluid to act on the valve members for maintaining the latter operated independently of the pilot fluid operation, enlarged piston means in said auxiliary valve and adapted for operation by the main fluid pressure to re-set the valve member, and also having in said auxiliary valve a service port connected to the piston end of said advancing hydraulic jack and a pressure port connected to said main control valve and to the annulus sides of the hydraulic props and of the advancing hydraulic jack. Conveniently there is a plurality of similar mine roof supports and advancing hydraulic jacks, and a plurality of similar valves connected to said supports and jacks and jointly connected to a common pilot system.

The invention also provides long wall mining apparatus comprising a plurality of mine roof supports, having hydraulic props under control of main hydraulic contr l valves, and a conveyor adapted for relative advancements by advancing hydraulic jacks connected between them, and a plurality of auxiliary pilot-operable hydraulic valves in the hydraulic circuit, and wherein these valves have pressure and exhaust valve members operable from a pilot system for pressure fluid to pass to the piston ends of the advancing hydraulic jacks for advancing the conveyor, fluid chambers for the valve members in which the pressure fluid acts on the valve members to maintain them operated independently of the pilot system, and reset pistons of greater eflfective cross sectional areas than those of the valve members and operable for returning the valve members by fluid pressure applied to the reset pistons at the same time as to the annulus sides of the advancing hydraulic jacks and the hydraulic props by subsequent operation of the main control valves.

The above and other features of the invention set out in the appended claims are incorporated in the arrangement which will be hereinafter particularly described as a specific embodiment with reference to the accompanying drawings in which:

FIG. 1 is a general side view of a hydraulic mine roof support connected by a hydraulic circuit to an enlarged sectional view of an auxiliary pilot-operated hydraulic valve according to the invention.

FIG. 2 is a similar view to FIG. 1 showing the auxiliary valve operated.

FIG. 3 is a general diagrammatic plan view showing a series of mine roof supports in plan relationship with a working face conveyor.

Referring first to FIG. 3, the hydraulic mine roof supports 1 to 16 are all of a type having four hydraulic props indicated by the centre lines CL and two of which are indicated in FIGS. 1 and 2 at 17 and 18. Each support also has a roof plate such as 19, FIGS. 1 and 2, a pair of cantilevers such as 20 pivoted to the head plate 19, a pair of further hydraulic props such as 21 under the cantilevers 20, and bases such as 22 whereat the supports incorporate horizontal conveyor-advancing hydraulic jacks such as 23 and the rams 23a of which are connected by links such as 24 to spill plates 25 of a working face conveyor 26.

Although FIG. 3 shows that each of the supports incorporates an advancing hydraulic jack, by which the supports can be advanced relatively to the conveyor, only a selection of the hydraulic jacks may be operated for advance of the conveyor relatively to the supports.

Referring to FIG. 1 each support is provided with a known type of 4-way hydraulic main control valve 27 which is connected to hydraulic pressure and return lines and is also connected by line L to the lower piston ends of the props and by line L1 to the upper annulus ends of the props.

The line L1 is also connected by line L2 to the annulus end of the advancing hydraulic jack cylinder 23b, this arrangement being so that operation of the main control valve 27 in the known manner to admit pressure fluid to line L will cause the props to extend and become set with the head plates 19 and cantilevers 20 supporting the roof, and with the line L1 open to exhaust for return of fluid from the upper annulus ends of the props. With the valve 27 further operated in known manner to open line L1 to pressure this causes release of the head plates 19 and cantilevers 20 from the roof and contraction of the props, while the line L is open to exhaust so that fluid from the lower piston ends of the props goes to exhaust.

At the same time that line L1 is open to pressure line L2 is also open to pressure which causes contraction of the advancing hydraulic jack 23 whereby the release of the props is immediately followed by contraction of the hydraulic jack 23 to advance the support relatively to the stationary conveyor.

To provide for advance of the conveyor, after the main control valve 27 has been operated to set the props, there is provided an auxiliary pilot-operated hydraulic valve such as 28 for each of those advancing hydraulic jacks 23 which are required to be operated for advancing the conveyor.

Each auxiliary valve 28 comprises a suitable valve block in which there is a first pressure port 30 connected to a first pressure fluid feed, a service port 31 connected to the service which in this instance is the piston end of the cylinder 23b and an exhaust port 33 connected to exhaust.

A slide valve member 37 is slidable in a mounting 38 in a pressure passage 29 with sealing 0 rings 39, 40, and having an end valve head 41 for co-operation with a valve seat opening 34 at one side of a pressure valve chamber 41a. In an exhaust passage 32 is a slide valve member 42 slidable in a mounting 43 with suitable sealing O ring 44, and having an end valve head 45 for co-operating with a valve seat opening 36 at the end of through openings 36a in the mounting 43.

It is to be noted, for reasons hereinafter to be given, that the slide valve members 37, 42 are disposed in parallel with their heads at like ends thereof but oppositely di rected to co-operate with their valve openings 34, 36.

For operating the valve members 37, 42 there is provided at the valve head ends of the valve members 37, 42, pilot operated pistons 46, 47 slidable in bearings 48, 49 with sealing 0 rings 50, 51 and disposed co-axially with the respective members 37, 42. The pistons 46, 47 project into an end chamber 52 which communicates via a connection 53 to a pilot power source as indicated by line L4.

This pilot system may be of hydraulic form or it may be of electric form operating a solenoid which in turn is adapted to cause the hydraulic pulses to be admitted at the connection 53.

At the other end of the valve member 37 there is a large area piston 54 with suitable O ring 55 and slidable in bearings 56, and at the equivalent end of the valve member 42 there is a large area piston 57 slidable in bearing 58 with suitable sealing O ring 59. The bearings communicate with an adjacent end chamber 60 which communicates by a second pressure port 61 to a line L5 extending to the main control valve 27 and to the annular ends of the props and the advancing hydraulic jack.

There also extends between the first pressure port 30 and the service port 31, a pressure passage which is formed by the valve chamber 41a accommodating the head 41 of the pressure valve member 37, the valve-seatopening 34 in the side of the pressure valve chamber 41a, an exhaust valve 'chamber 32a in which the head 45 of the exhaust valve member 42 is accommodated, and a pressure duct 35 which inter-communicates between the pressure valve-seat-opening 34 and the exhaust valve chamber 32a.

When it is required for the conveyor to be advanced it is necessary that the particular mine roof supports connected with the pushing operation be staked to the roof, and in this position, line L will be pressurised and line L1 and L5 will be open to exhaust. Thus when the conveyor is to be advanced by operation of a group of hydraulic jacks 23 which are required to advance a section of the conveyor, the auxiliary valves 28 associated with these hydraulic jacks 23 are all operated simultaneously by the pilot system. Each auxiliary valve operates by a hydraulic signal which can be of very short duration from the line L4 entering the connection 53 and acting in the chamber 52 to operate the pistons 46, 47 which in turn thrust against the heads 42, 45 of the valve members 37, 42 and displaces these members, together with the large area pistons 54, 57 from the position shown in FIG. 1 towards the left to the position shown in FIG. 2.

This causes the valve head 45 to close the valve-seatopening 36 whereby the piston end of the cylinder 23b is closed to the exhaust port 33. It also causes the valve head 41 to open the valve-seat-opening 34 thereby opening the first pressure port 30, via the pressure valve chamber 41a, the valve-seat-opening 34, the communicating duct '35, and the exhaust valve chamber 32a, to the service port 31 and via line L3 to the piston end of the cylinder 23. By this means pressure fluid passes to the piston end of the cylinder 23b to extend the hydraulic jacks 23 which consequently advances the conveyor 26 as shown in FIG. 2.

Since for this purpose the pressure fluid passes through the pressure valve chambers 41a and 32a at the right hand side of the valve heads 41, 45 in FIG. 2, the pressure fluid also functions to hold the valve members 37, 42 in their operated positions in substitution for the operation of the pistons 46, 47 by the pilot system.

Consequently the pilot system can be thereafter employed for any other purpose desired, and since the pilot Signal is of only short duration, it can be of electrical kind with little or no danger.

The valve members 37 and 42 are thus maintained operated by the fluid pressure until the group of hydraulic jacks 23 have all fully operated under control of their respective pilot-operated valves which have all been operated simultaneously. In other words the group of pilotoperated valves are maintained operated by the pressure fluid until a section of the conveyor such as shown inclined in FIG. 3 has been advanced into a position aligned with the next adjacent previously advanced section.

During the whole of this period the pilot system remains free to be employed for any other purpose desired.

When the conveyor section has been advanced the mine roof supports may be released singly from the roof and advanced to their new position adjacent to the conveyor.

This is accomplished when the main control valve 27 is operated to open the fluid pressure feed to line L1, and

to open line L to exhaust, thereby to cause lowering of the roof plate '19 from the roof. Fluid pressure from line L1 will also act, via line L5 and the second pressure port 61, in the chamber 60 to apply pressure to the large area pistons 54, 57.

Due to overbalance of the efiective cross sectional areas of the pistons 54, 57 in relation to the valve heads 41, 45 of the valve members37, 42, the pressure acting on the piston 54 will operate it to return the valve member 37 from the position of FIG. 2 to the position of FIG. 1 so as to close the valve seat opening 34. Pressure acting on the piston 57 operates it to return the valve member 42 so as to open the valve seat opening 36.

It will thus be seen that the re-setting of the auxiliary valves is effected through the operations of releasing the props, i.e. by virtue of the line L5, and consequently, throughout the interim period, the auxiliary valves have been held operated by the main fluid pressure thus causing the rams 23a to be continuously pushing against the conveyor throughout the same period.

Since the valve member 37 .is now in closed position and the valve member 42 is in open position the piston end of the cylinder 23b will be open to exhaust, and fluid pressure acting from line L1 via line L2 in the annulus end of the cylinder 23b will retract the ram 23a. This will, in turn, pull the mine roof support up to the conveyor.

It will be noted that when the support has been moved fully forward, and the valve 27 has been operated to reset the support to the roof, the lines L1, L5 and the second pressure port 61 will be open to exhaust, but the valve members 37, 42 will remain in their respective closed and open positions due to fluid pressure through the first pressure port 30 acting against the rear of the valve heads 41, 45.

These operations occur singly until the supports of the whole batch have been moved forward to their new position.

What I claim is:

1. A mine roof support system comprising a mine roof support, at least one hydraulic prop in said support, a conveyor, an advancing hydraulic jack connected between said support and said conveyor, a main hydraulic control valve for said support, an auxiliary pilot-fluidoperable hydraulic valve in said support, pressure and exhaust valve in said support, pressure and exhaust valve members in said auxiliary valve and which are pilot-fluidoperable in one direction for opening the auxiliary valve to a main pressure fluid feed, passage means in said auxiliary valve associated with the pressure and exhaust valve members and adapted for guiding the main pressure fluid to act on the valve members for maintaining the latter operated independently of the pilot fluid operation, enlarged piston means in said auxiliary valve and adapted for operation by the main fluid pressure to reset the valve member, and also having in said auxiliary valve a service port connected to the piston end of said advancing hydraulic jack and a pressure port connected to said main control valve and to the annulus sides of the hydraulic props and of the advancing hydraulic jack.

2. A system according to claim (1 wherein there is a plurality of similar mine roof supports and advancing hydraulic jacks, and a plurality of similar valves connected to said supports and jacks and jointly connected to a common pilot system.

3. Long wall mining apparatus comprising a plurality of mine roof supports, having hydraulic props under control of main hydraulic control valves, and a conveyor adapted for relative advancements by advancing hydraulic jacks connected between them, and a plurality of auxiliary pilot-operable hydraulic valves in the hydraulic circuit, and wherein these valves have pressure and exhaust valve members operable from a pilot system for pressure fluid to pass to the piston ends of the advancing hydraulic jacks for advancing the conveyor, fluid chambers for the valve members in which the pressure fluid acts on the valve members to maintain them thus operated independently of the pilot system, and reset pistons of greater eifective cross sectional areas than those of the valve members and operable for returning the valve members by fluid pressure applied to the reset pistons at the same time as to the annulus sides of the advancing hydraulic jacks and the hydraulic props by subsequent operation of the main control valves.

4. A mine roof support system comprising a roof support having at least one hydraulic prop and an advance hydraulic jack; a conveyor connected with the jack, and a hydraulic circuit including a pressure liquid supply line, a main valve connected with the supply line, flow lines connecting the main valve with a retraction side of the advance hydraulic jack and with extension and retraction sides of the prop, the main valve being operable to connect the supply line alternately with the extension side of the prop and with the retraction sides of the prop and the advance hydraulic jack, and a pilot valve, said pilot valve having a pressure liquid inlet, a pressure liquid outlet connected with the extension side of the advance hydraulic jack, an exhaust port, valve means movable between first and second positions wherein the valve means connects the inlet with the outlet and the outlet with the exhaust port respectively, hydraulic pulse responsive means actuable to act on a part of the valve means so as to move the latter from the second position to the first position, said part of the valve means being responsive to hold the valve means in said first position, and liquid pressure responsive means actuable to move the valve means from the first position to the second position wherein liquid pressure applied at the inlet is not elfective on said part of the valve means.

References Cited UNITED STATES PATENTS 2,778,378 1/1957 Presnell 91412 X 2,952,244 9/1960 Krauss et al. 9l361 X 3,309,880 3/1967 Potts et al. 61-45 3,437,011 4/ 1969 Van Gelder 91--412 DENNIS L. TAYLOR, Primary Examiner.

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