GB1593832A - Mine roof support control - Google Patents

Description

(54) MINE ROOF SUPPORT CONTROL (71) We, GULLICK DOBSON LIMITED, a British Company, of Ince, Wigan, Lancashire, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The invention relates to controlling mine roof supports.

It is common practice to support mine roofs by pressure fluid operated, usually hydraulic, ram or props, often in self-advancing support structures having a plurality of props connected between floor-engaging and roof-engaging structures. Generally mine roof support props are associated with control valve gear for setting them between floor and roof of a working using a locally available fluid pressure.

It is an object of this invention to enhance the roof-support capabilities and performance of pressure-fluid operated props and, to this end, there is provided mine roof support prop control apparatus comprising a prop setting selection control valve operable to provide floor-to-roof extension of an hydraulic prop or props, and means operative automatically in response to movement of the control valve away from a prop-setting or extension position to result in injection of further fluid into and/or increasing fluid pressure in one or more props after such extension thereof.

Thus, in preferred embodiments. the prop fluid injection and/or pressure increase does not require an additional operation of the selection valve following release or return of the selection valve from its prop extension, usually setting, position to some other position, say a neutral position.

This is readily achieved by use of a pressure intensifier that is deactivated on selection of prop-extension and activated or reactivated on movement of the selection valve from its prop extension selection position, or at least to one other selectable position. Such implementation allows a presently available floor-to-roof setting prop pressure to be achieved using a lower pressure supply than hitherto or, and usually, a further enhancement of the floor-to-roof prop setting pressure above what is available on present pressure supplies. In this way, not only may roof support capabilities be improved, but, and importantly on a self advancing mine roof support, improved anchorage is provided for relative advancement of supports themselves and an advanceable anchorage, such as a face-conveyor, to which such supports are coupled by pressure advancing rams.

One suitable pressure intensifier is of differential piston area type with a larger piston area for receiving the available fluid pressure supply and a smaller piston area facing the setting feed lines to the props, say with a pilot-operated flow control valve coupled to selection valve gear and switchable in response to the position thereof between states wherein pressure fluid supply is applied to the large piston area and wherein pressure fluid can drain from that large piston area to the pressure fluid return, preferably in a self-priming manner as normal prop setting is selected so that the intensifier is ready to operate immediately on completion of normal prop setting.

One embodiment of the invention will now be particularly described, by way of example with reference to the accompanying drawings, in which: Figure I shows a typical six prop selfadvancing support; Figure 2 is a block and line diagram of control apparatus embodying this invention as applied to a support of the type of Figure l; Figure 3 shows a typical dead-mans handle type selection valve; and Figure 4 is a section through a preferred pressure intensifier.

In Figure 1, a self-advancing mine roof support 10 has a floor-engaging structure or base 11, a roof-engaging structure 12 comprising a main roof bar or canopy 13 and an articulated forward cantilever 14, and rear, mid and forward pairs of hydraulically operated props 15, 16 and 17, respectively, by means of which the height of the roofengaging structure 12 above the base 11 is adjustable.

As shown in Figure 2, the props 15, 16 and 17 are connected by hydraulic fluid lines 25, 26 and 27, respectively, to control valve gear, specifically to striker-overridable non-return valves 28, 29 and 30, respectively, thereof.

Line 31 is provided for hydraulic pressure fluid to raise the rear and mid props 13 and 16 and set them to the roof, and also for permitting lowering thereof. Similarly, line 32 offers a hydraulic feed and return for the front props 17. Corresponding lines 33 and 34 serve to operate the strikers of valves 28 and 29, and 30, respectively, for prop release.

The lines 31 to 34 extend from different ports 35 of a pressure fluid supply selection vave 36 of conventional type wherein a cylindrical body 37 has a ring of such ports and a central supply passage 38 with a dead-man's handle control of a routing disc channelled and apertured to communicate between the central passage 38 and a selected one of the ports 35, the passage 38 being shown connected at 43 to a main hydraulic fluid feed line 44.

Thus, and as shown, the rear and mid props 15 and 16 are selectable together for raising or lowering and the front props 17 are independently selectable. If desired, of course, the props may be double acting with the lines 33 and 34 branched to feed pressure fluid to the other sides of the prop pistons.

For the purposes of the described embodiment of the present invention, a pressure intensifier 50 is shown with connection via non-return valves 5 1, 52 and 53 and lines 54, 55 and 56 to the hydraulic prop lines 25, 26 and 27, respectively. The valves 51, 52 and 53 communicate with a cylinder 57 in which runs a relatively small area piston part 58 of a differential area piston 59 having its other and large area piston part 60 in a larger cylinder 61 communicating over line 62 with port no. 2 of a pilot-operated flow control valve 63. The relatively small cylinder 57 also communicates via an oppositely directed non-return valve 65 with branch line 66 from the prop raise line 31 for the rear and mid props 15 and 16. Another branch 67 from line 31 is shown connected to port no. 4 of the pilot-operated flow control valve 63, ports nos.I and 3 thereof being coupled via lines 68 and 69 to main return and feed lines 70 and 44, respectively.

The operation of the pilot valves 63 is such that, when there is pressure in line 3 1 and thus at its port no. 4, ports nos. I and 2 are in communication so that hydraulic fluid will drain from the larger cylinder 61 of the intensifier 62. Otherwise. or at least in a neutral position of the selection valve 36, port no. 4 is not pressurised and ports nos. 2 and 3 are in communication so that pressurised fluid is applied to cylinder 61. This allows normal prop raising and setting to the roof of a mine working at the pressure available in line 44, followed by automatic increase of that pressure by injection of hydraulic fluid from the intensifier 62.

It will be noted that the pressure intensifier serves all of the props of the support but that it is itself primed only when the main roof bar props 15 and 16 are set to the roof. This allows independent release of the cantilever props 17 and resetting thereof without automatic boosting of pressure therein, say to avoid any tendency for the front edge of the canopy to dig into the roof. Also, of course, the automatic prop pressure boosting will be inoperative if the cantilever props 17 are not set to the roof in the normal manner prior to setting the main roof bar or canopy props 15 and 16.

In general it has been found satisfactory for the pressure intensifier to have a capacity sufficient to inject enough hydraulic fluid to raise all of the served props by about one inch and for the pressure intensifier to have a 2:1 ratio of differential piston areas.

Plainly, embodiments of the invention are applicable to some or all props of any selfadvancing support whether or not there is a base to roof cantilever prop or more than one such prop and regardless of the number of main roof bar props and whether all are concerned. Extended supports as at face ends may also have some or all of their props subject to automatic pressure boost and such boost might also be selectively or automatically applicable to side or rear support structures or shields or even to the advancing ram in addition to one or more base to roof props.

A particular construction of selection valve 36', is shown in greater detail in Figure 3 and has a dead man's handle 39 able to rotate a routing element 40 and, when lifted operate a plunger 41 to unseat a spring loaded poppet 42 to allow hydraulic fluid flow from line or part 43 in a body part 45 centrally through the routing element 40 into a cross bore 46.

The body 45 also has the ports 35 formed therein with communication to a ring of bores (not shown) registering with the path of travel of a spring loaded tubular valve pad 47 to establish selective communication with cross bore 46 and thus supply port 43.

Accurate registration is assisted by a spring loaded detent arrangement 48 cooperating with recesses on the casing for the routing element 40.

Also shown in Figure 3 is an exhaust port E in the valve body 45 and, which coperates with chamber 49 and restrictor 50 in the bore 46 to allow draining of pressure from the valve interior following an operation thereof and thus materially ease subsequent operation thereof. The restrictor 50 will be sized to ensure that predetermined pressures are maintained to selected port 35.

One suitable fluid injection and pressure intensifier 62' is shown in the sectional view of Figure 4, wherein a tubular casing 72 closed at one end by a welded-on plate 73 having a fluid inlet passage 73 for the line 62 of Figure 2 forms a cylinder 74 housing a telescopic piston assembly 75, 76. Outer hollow piston 75 is sealed against the cylinder 74 at 77 and 78 and receives fluid pressure from inlet passage 73. Inner hollow piston 76 is sealed at 79 against bore 80 in outer piston 74 with its enlarged head 81 slidable in the cylinder 74 and retained by ring 82. Interior bore 83 of the inner piston 76 is in open communication with the outer piston bore 80 forming therewith a variable volume chamber 84 which receives fluid via passage 85 from the one-way valve 65 in a valve housing well 86 let into the head end of the inner piston 76.Only valve 51 of the oppositely operating one-way valves 51, 52, 53 is shown in another housing well 87 also let into the head-end of inner piston 76 communication with the chamber 84 for fluid outflow via a passage 88. It will be understood that three such passageways 88 will be provided at spaced intervals, are for each of the valves 51, 52, 53.

In operation, when the props extension position is selected by the valve 36 of Figure 2, the pressure fluid supply to the inlet passage 73 will be cut off and return connected thereto by the valve 63 with prop extension fluid pressure supplied via the valve 65 to prime the intensifier 62' to the state shown in Figure 4. After the valve 36 is moved from the props extension position, pressure fluid supply will be reconnected via valve 63 to the passage 73 and will force the outer piston 75 along the cylinder 74 to inject fluid into the props via the valves 51, 52 and 53 thereby increasing the extension thereof or at least the pressure therein.

Clearly, the inner piston 76 may be fixed relative to the casing 72 without affecting operation, though dismantling may be less easy.

WHAT WE CLAIM IS:- 1. Mine roof support prop control apparatus comprising a prop setting selection control valve operable to provide floor-toroof extension of an hydraulic prop or props.

and means operative automatically in response to movement of the control valve away from a prop-setting or extension position to result in injection of further fluid into and/or increasing fluid pressure in one or more props after such extension thereof.

2. Apparatus according to claim 1, wherein the last-mentioned means includes a pressure intensifier.

3. Apparatus according to claim 2, wherein the pressure intensifier is operative from a pressure fluid supply for normal prop setting purposes.

4. Apparatus according to claim 2 or claims 3, wherein the pressure intensifier is deactivated on control valve selection of prop-setting or extension.

5. Apparatus according to claim 4, wherein the pressure intensifier is activated or reactivated after cessation of such selection.

6. Apparatus according to claim 3, 4 or 5, wherein the pressure intensifier comprises a differential area piston with a larger area piston part for receiving pressurised fluid and a smaller area piston part facing extension feed lines of the prop or props.

7. Apparatus according to claim 6, wherein one-way valving to the smaller area piston part allows normal prop setting or extension pressure fluid to prime the pressure intensifier.

8. Apparatus according to any one of claims 3 to 7, further comprising pilotoperated flow control valve means for determining whether fluid pressure supply or exhaust is coupled thereto.

9. Apparatus according to claim 8, wherein the pilot-operated valve means is connected to be responsive to pressure fluid applied to the props on normal prop-setting or extension as selected by the control valve.

10. Apparatus according to any preceding claim incorporated in a self-advancing mine roof support.

I I. Apparatus according to claim 10, wherein the control valve also serves to select for support advance operations.

12. Apparatus according to claim 11, wherein the means for injecting further fluid and/or increasing fluid pressure is deactivated only when prop release is selected by the control valve.

13. Apparatus according to claim 10,11 or 12, wherein the support has main roof bar or canopy support props and one or more cantilever support props.

14. Apparatus according to claim 13, wherein the means for injecting further fluid and/or increasing fluid pressure is made subsequently operative only on selection of the main roof bar or canopy support props.

15. Apparatus according to claim 13, wherein the means for injecting further fluid and/or increasing fluid pressure is subsequently operative both with respect to the main roof bar or canopy props and the or each cantilever support prop.

16. A self-advancing mine roof support arranged and adapted to operate substantially as herein described with reference to and as shown in Figures I and 2 of the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (16)

**WARNING** start of CLMS field may overlap end of DESC **. intensifier 62' is shown in the sectional view of Figure 4, wherein a tubular casing 72 closed at one end by a welded-on plate 73 having a fluid inlet passage 73 for the line 62 of Figure 2 forms a cylinder 74 housing a telescopic piston assembly 75, 76. Outer hollow piston 75 is sealed against the cylinder 74 at 77 and 78 and receives fluid pressure from inlet passage 73. Inner hollow piston 76 is sealed at 79 against bore 80 in outer piston 74 with its enlarged head 81 slidable in the cylinder 74 and retained by ring 82. Interior bore 83 of the inner piston 76 is in open communication with the outer piston bore 80 forming therewith a variable volume chamber 84 which receives fluid via passage 85 from the one-way valve 65 in a valve housing well 86 let into the head end of the inner piston 76.Only valve 51 of the oppositely operating one-way valves 51, 52, 53 is shown in another housing well 87 also let into the head-end of inner piston 76 communication with the chamber 84 for fluid outflow via a passage 88. It will be understood that three such passageways 88 will be provided at spaced intervals, are for each of the valves 51, 52, 53. In operation, when the props extension position is selected by the valve 36 of Figure 2, the pressure fluid supply to the inlet passage 73 will be cut off and return connected thereto by the valve 63 with prop extension fluid pressure supplied via the valve 65 to prime the intensifier 62' to the state shown in Figure 4. After the valve 36 is moved from the props extension position, pressure fluid supply will be reconnected via valve 63 to the passage 73 and will force the outer piston 75 along the cylinder 74 to inject fluid into the props via the valves 51, 52 and 53 thereby increasing the extension thereof or at least the pressure therein. Clearly, the inner piston 76 may be fixed relative to the casing 72 without affecting operation, though dismantling may be less easy. WHAT WE CLAIM IS:-

1. Mine roof support prop control apparatus comprising a prop setting selection control valve operable to provide floor-toroof extension of an hydraulic prop or props.

and means operative automatically in response to movement of the control valve away from a prop-setting or extension position to result in injection of further fluid into and/or increasing fluid pressure in one or more props after such extension thereof.

2. Apparatus according to claim 1, wherein the last-mentioned means includes a pressure intensifier.

3. Apparatus according to claim 2, wherein the pressure intensifier is operative from a pressure fluid supply for normal prop setting purposes.

4. Apparatus according to claim 2 or claims 3, wherein the pressure intensifier is deactivated on control valve selection of prop-setting or extension.

5. Apparatus according to claim 4, wherein the pressure intensifier is activated or reactivated after cessation of such selection.

6. Apparatus according to claim 3, 4 or 5, wherein the pressure intensifier comprises a differential area piston with a larger area piston part for receiving pressurised fluid and a smaller area piston part facing extension feed lines of the prop or props.

7. Apparatus according to claim 6, wherein one-way valving to the smaller area piston part allows normal prop setting or extension pressure fluid to prime the pressure intensifier.

8. Apparatus according to any one of claims 3 to 7, further comprising pilotoperated flow control valve means for determining whether fluid pressure supply or exhaust is coupled thereto.

9. Apparatus according to claim 8, wherein the pilot-operated valve means is connected to be responsive to pressure fluid applied to the props on normal prop-setting or extension as selected by the control valve.

10. Apparatus according to any preceding claim incorporated in a self-advancing mine roof support.

I I. Apparatus according to claim 10, wherein the control valve also serves to select for support advance operations.

12. Apparatus according to claim 11, wherein the means for injecting further fluid and/or increasing fluid pressure is deactivated only when prop release is selected by the control valve.

13. Apparatus according to claim 10,11 or 12, wherein the support has main roof bar or canopy support props and one or more cantilever support props.

14. Apparatus according to claim 13, wherein the means for injecting further fluid and/or increasing fluid pressure is made subsequently operative only on selection of the main roof bar or canopy support props.

15. Apparatus according to claim 13, wherein the means for injecting further fluid and/or increasing fluid pressure is subsequently operative both with respect to the main roof bar or canopy props and the or each cantilever support prop.

16. A self-advancing mine roof support arranged and adapted to operate substantially as herein described with reference to and as shown in Figures I and 2 of the accompanying drawings.