GB2169022A

GB2169022A - Control valve and control system for multi-leg mine roof supports

Info

Publication number: GB2169022A
Application number: GB08531101A
Authority: GB
Inventors: Russell Stuart Turner
Original assignee: Fletcher Sutcliffe Wild Ltd
Current assignee: Fletcher Sutcliffe Wild Ltd
Priority date: 1984-12-22
Filing date: 1985-12-18
Publication date: 1986-07-02
Also published as: GB8432568D0; GB8531101D0

Abstract

A control valve 6 for hydraulic fluid comprising a valve body 9 having first and second ports 10, 11, the first port 10 housing a poppet valve member 12 which is spring loaded into a closed position and displaceable to an open position against the action of the spring 13 under the influence of fluid pressure, the first port 10 being intersected by an inlet port 16 connectable to a pressure fluid supply line 7, the second port 11 housing two opposed, spring-loaded check valves 18, a transfer port 17 connecting the first port 10 downstream of the valve member 12 thereof to a zone of the second port 11 common to portions of both check valves 18, which are openable upon fluid passing through the first port 10 to the second port 11 via the transfer port 17. The invention also includes a control system for a multi-leg mine roof support comprising a main valve (2, Fig. 1), two leg circuits 4A and 4B for controlling respectively actuation of forward and rearward, hydraulically extensible chock legs 1A and 1B, and a valve 6 as defined above. <IMAGE>

Description

SPECIFICATION Control valve and control system for multileg mine roof supports This invention relates to a control valve for hydraulic fluid and to a control system for a multi-leg mine roof support of the self-advancing, hydraulically powered kind, as are used extensively in longwall mining operations.

In GB Patent 2042035 is described a control system in which maintenance of a connection between a hydraulically extensible chock leg along a pressure fluid feed line connected between the leg and a conventionally provided mains pressure line extending along a mineral face is ensured via an auxilliary valve, irrespective of how long a main, manually operable valve is kept open by the support operator, until the leg pressure stabilises at the mains pressure. However, with a chock having two forward and two rearward legs for example, with the legs extending between a base means seated on the mine floor and a common canopy engaging the mine roof, the front legs are, by regulation, on a different leg circuit from the rear legs, thus necessitating the presence of two auxilliary valves.Because of irregularities in the mine roof, it is frequently the case that the front of the canopy strikes the mine roof before the rear, or vice versa, and in this circumstance, it is often difficult for the operator to appreciate whether the front legs or the rear legs are urging the canopy into roof engagement, and hence which legs have first set, or are in the process of being set, to the roof by fluid pressure supply from the mains via the auxiliary valve of the leg circuit, while furthermore the "non-set" leg circuit may be at a fluid pressure below the nominal mains pressure e.g. 800 p.s.i., and the main valve of this low pressure leg circuit may be released prematurely by the chock operator before the auxilliary valve has been triggered and hence before chock leg pressure stabilisation at the mains pressure can be ensured by the auxilliary valve.

According to a first aspect of the present invention, there is provided a control valve for hydraulic fluid comprising a valve body having first and second ports the first port housing a poppet valve member which is spring loaded into a closed position and displaceable to an open position against the action of the spring under the influence of fluid pressure, the first port being intersected by an inlet port connectable to a pressure fluid supply line, the second port housing two opposed, spring-loaded check valves, a transfer port connecting the first port downstream of the valve member thereof to a zone of the second port common to portions of both check valves, which are openable upon fluid passing through the first port to the second port via the transfer port.

According to a second aspect of the present invention, there is provided a control system for a multi-leg mine roof support comprising a main control valve, for hydraulic fluid, at least two leg circuits, for controlling respectively actuation of at least one forward and at least one rearward, hydraulically extensible chock leg and a control valve for the leg circuits comprising a valve body having first and second ports the first port housing a poppet valve member which is spring-loaded into a closed position and displaceable to an open position against the action of the spring under the influence of fluid pressure, the first port being intersected by an inlet port connectable to a pressure fluid supply line, the second port housing two opposed, spring-loaded check valves, a transfer port connecting the first port downstream of the valve member thereof to a zone of the second port common to portions of both check valves, which are openable upon fluid passing through the first port to the second port via the transfer port, each check valve controlling admission of pressure fluid to one leg circuit.

Thus, the control valve and system in accordance with the invention, by providing two check valves on the fluid delivery side ensures the setting of both the forward leg(s) and the rearward leg(s) at the supply line pressure.

One embodiment of control valve in accordance with the first aspect will now be described in greater detail, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a diagrammatic arrangement of a control system in accordance with the second aspect of the invention; and Figure 2 is a sectional view through a control valve in accordance with the first aspect of the invention.

In the drawings, a control system for a multi-leg mine roof support (not shown), having at least one forwardly located, hydraulically extensible chock leg 1A, and at least one rearwardly located, hydraulically extensible chock leg 1 B, comprises a main control valve 2 supplied with pressure fluid from a line 3 connected to a source of pressurised fluid, and two leg circuits being a forward leg circuit 4A fior the forward leg(s) 1A and a rearward leg circuit 4B for the rearward leg(s) 1B. A line 5 extends between the main valve 2 and an auxillary valve 6 which is detailed in Fig. 2, from which valve 6 the leg circuits 4A and 4B extend.In accordance with the proposals of our GB Patent 2042035, a by-pass line 7 is connected between the auxillary valve 6 and to the line 3 at a location upstream of the main valve 2, the by-pass line 7 incorporating a shut-off valve 8.

The auxillary valve 6 comprises a valve body 9 having first and second ports 10, 11 respectively, the first port 10 housing a poppet valve member 12 which is loaded by a spring 13 into a closed position against a seat 14 and is displaceable to an open position, against the action of its spring 13, under the influence of fluid pressure in line 4A acting on a head 15 of the valve member 12. The first port 10 is intersected by an inlet port 16 connected to the line 7, while a transfer port 17 connects the first port 10, downstream of its valve member 12, to a zone of the second port 11 intermediate a pair of opposed, spring-loaded check valves 18 located in the second port 11, each check valve 18 being urged by a spring 19 into a closed position against a seat 20, and being displaced from such closed position upon fluid passing through the first port 10 to the second port 11 via the transfer port 17, with both check valves 18 thus insuring fluid delivery and hence setting of both the forward legs 1A, and the rearward legs 1B, at the pressure of the supply line 3.

Claims

1. A control valve for hydraulic fluid comprising a valve body having first and second ports the first port housing a poppet valve member which is spring loaded into a closed position and displaceable to an open position against the action of the spring under the influence of fluid pressure, the first port being intersected by an inlet port connectable to a pressure fluid supply line, the second port housing two opposed, spring-loaded check valves, a transfer port connecting the first port downstream of the valve member thereof to a zone of the second port common to portions of both check valves, which are openable upon fluid passing through the first port to the second port via the transfer port.

2. A control system for a multi-leg mine roof support comprisng a main control valve, for hydraulic fluid, at least two leg circuits, for controlling respectively actuation of at least one forward and at least one rearward, hydraulically extensible chock leg and a control valve for the leg circuits comprising a valve body having first and second ports the first port housing a poppet valve member which is spring-loaded into a closed position and displaceable to an open position against the action of the spring under the influence of fluid pressure, the first port being intersected by an inlet port connectable to a pressure fluid supply line, the second port housing two opposed, spring-loaded check valves, a transfer port connecting the first port downstream of the valve member thereof to a zone of the second port common to portions of both check valves, which are openable upon fluid passing through the first port to the second port via the transfer port, each check valve controlling admission of pressure fluid to one leg circuit.

3. A control valve substantially as hereinbefore described with reference to the accompanying drawings.

4. A control system substantially as hereinbefore described with reference to the accompanying drawings.