GB2329428A

GB2329428A - Improvements in and relating to a hydraulic control system

Info

Publication number: GB2329428A
Application number: GB9719967A
Authority: GB
Inventors: Peter Elliot-Moore
Original assignee: JOY MINING MACHINERY Ltd
Current assignee: JOY MINING MACHINERY Ltd
Priority date: 1997-09-20
Filing date: 1997-09-20
Publication date: 1999-03-24
Also published as: DE19842717A1; AU8608798A; GB9719967D0

Abstract

The present invention provides a hydraulic control system for a roof support arrangement (2) having at least two hydraulically operated rams (18,20,22,24), each having an hydraulic input (72,74,76,78) and a corresponding valve (100,102,104,106) to control the flow of hydraulic fluid therethrough, wherein the valve (100,102,104,106) is proximate to the corresponding ram (18,20,22,24).

Description

2329428 IMPROVEMENTS IN AND RELATING TO A HYDRAULIC CONTROL SYSTEM

Field of the Invention

The present invention relates to hydraulic control systems for roof support arrangements and to roof support arrangements comprising such control systems.

Background to the Invention

Hydraulic mine roof supports are well known and generally comprise a ground engaging base, a roof engaging canopy and a plurality of support legs each comprising a is hydraulic jack extending between the base and the canopy. Each leg is controlled by a control unit coupled to a hydraulic system.

Typically four hydraulic rams are used in a conventional roof support: an advancing ram for advancing the roof support arrangement relative to the work face; a f irst leg driving ram, a second leg driving ram and a compensating ram for controlling the angle between the roof engaging canopy and a shield as is known in the art. The four rams are fed with hydraulic fluid from a central distribution unit containing solenoid controlled valves for each service line running to each ram.

Such a central distribution unit places restrictions on the design of the roof support due to the space it occupies and can require additional maintenance. Furthermore, the arrangement adds to the complexity of manufacture. In the context of the operating environment of a mine roof support, the central distribution unit is relatively distant from the relevant rams.

2 - It is an aim of preferred embodiments of the present invention to obviate or overcome disadvantages encountered in relation to the prior art, whether referred to herein or otherwise.

Summary of the Invention

According to the present invention in a first aspect, there is provided a hydraulic control system for a roof support arrangement having at least two hydraulically operated rams, each unit having a hydraulic input and a corresponding valve to control the flow of hydraulic fluid therethrough, wherein the valve is proximate to the corresponding ram.

Such an arrangement can dispense with the need for extensive service lines and a central distribution unit.

Suitably, the at least two valves are integral with the corresponding units. Alternatively, the at least two valves are provided in manifolds on the corresponding units.

Suitably, there is provided a source of hydraulic fluid forming a continuous loop from which at least one of the at least two hydraulically operated rams takes a feed line to its hydraulic input.

Suitably, the at least two valves are operated by a solenoid which solenoids are proximate to the corresponding valve. Suitably, the at least two solenoids are integral with the corresponding ram.

Suitably, there is provided a return line forming a continuous loop and a spur extending to at least one of the at least two rams.

is According to the present invention in a second aspect, there is provided a roof support leg arrangement comprising a hydraulic control system according to the first aspect of the invention.

Brief Description of the Drawings

The present invention will now be described, by way of example only with reference to the drawings that follow; in which:

Figure 1 is a schematic side elevation of a hydraulic mine roof support.

Figure 2 is a functional diagram of a known hydraulic 20 control system.

Figure 3 is a functional diagram of a hydraulic control system according to the present invention.

Description of the Preferred Embodiment

Referring to Figure 1 of the drawings that follow, there is shown a mine roof support 2 having a ground engaging base 4 and a roof engaging canopy 6, interconnected by a rear shield 8 and pivoting links 10. A pair of hydraulic support legs 12 act between the base 4 and the canopy 6. The angle between the canopy 6 and the shield 8 is controlled by a compensating ram 14 which can be hydraulically locked. Each base 4 includes an advancing ram (not shown).

- 4 is Referring" to Figure 2 of the drawings that follow, there is shown a known hydraulic control system for a roof support arrangement comprising an advancing ram 18, a first leg driving ram 20, a second leg driving ram 22 and a compensating ram 24. Hydraulic fluid under pressure is provided from a hydraulic source (not shown) via main pressure line 26 to a central distribution unit 28 from which service lines extend to each of the rams 18-24..Specifically, from a first central valve 30, a first service line 32 extends to first leg driving ram 20, from a second central valve 34, a second service line 36 extends to first leg driving ram 20 and to second leg driving ram 22; from third central valve 38 a third service line 40 extends to compensating ram 24; from fourth central valve 42 a fourth service line 44 also extends to compensating ram 24; from fifth central valve 46, a fifth service line 48 extends to second leg driving ram 22; from sixth central valve 50; a sixth service line 52 extends to advancing ram 18 and from seventh central valve 54 a seventh service line 56 also extends to advancing ram 18. An eighth central valve 58 is used in conjunction with central valve 54. Each central valve has a corresponding solenoid (not shown) to open and close it, which solenoids are controlled by a control unit 60. Control unit 60 is electrically connected via electrical lines 62 to first leg driving ram 20, second leg driving ram 22 and advancing ram 18 to receive monitoring signals therefrom for control purposes. The electrical lines 62 run through central distribution unit 28.

A main return pressure line 64 connects compensating ram 24 to return via central distribution unit 28 along line 65.

Referring to Figure 3 of the drawings that follow, a hydraulic control arrangement according to the present invention is shown.

A generally similar advancing ram 18, first leg driving ram 20, second leg driving ram 22 and compensating ram 24 as in Figure 2 are shown in Figure 3. A main pressure line manifold 66 provides a main pressure line 67 as an inter-support supply, leading in each roof support to a pressure loop 68 fed via arm 70. Pressure loop 68 forms a continuous supply loop from which first pressure feed spur 72 extends to first leg driving ram 20, second pressure spur line 74 extends to advancing ram 18, third pressure feed spur 76 extends to compensating ram 24 and is fourth pressure spur line 78 extends to second leg driving ram 22.

Each ram 18-24 has at least one corresponding solenoid to control a valve each of which are built into the ram integrally. The solenoids and valves for each of the advancing ram 18, first leg driving ram 20, second leg driving ram 22 and compensating ram 24 are indicated schematically by reference numerals 100, 102, 104 and 106 respectively. A control unit 80 controls each solenoid via a control loop 82. Although shown as a loop 82 with spurs 84, the electrical control is via separate wires (or optical links) to each solenoid. Conveniently, the electrical control wires 82, 84 can run alongside the hydraulic lines.

A main return line manifold 86 is provided as to supply a return line 87 an inter-leg line leading in each roof support to a pressure return loop 88 connected via arm 90. Pressure return loop 88 forms a continuous return loop from which first return spur 92 extends to first leg - 6 driving ram 20, second return spur 94 extends to advancing ram 18, third return spur 96 extends to compensating ram 24 and fourth return spur 98 extends to second leg driving ram 22.

To incorporate the valves/solenoids, the outer cylinders of the rams may either be made from special extrusions or be fabricated to accept the control valves/solenoids. The valves/ solenoids could either be directly assembled into the cylinder or manifold mounted thereon.

It is noted that there is no significant requirement for service lines in the arrangement according to the is preferred embodiment of the present invention, nor for a central distribution unit.

Where we have referred to hydraulic spool valves, other valves can be used as well.

The reader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

7 Each feature disclosed in this specification (including any accompanying claims, abstract and drawings), may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not restricted to the details of the foregoing embodiment (s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

1. A hydraulic control system for a roof support arrangement having at least two hydraulically operated rams, each unit having a hydraulic input and a corresponding valve to control the flow of hydraulic fluid therethrough, wherein the valve is proximate to the corresponding ram.

2. A hydraulic control system in accordance with Claim 1, wherein said valve is integral with the corresponding unit.

3. A hydraulic control unit in accordance with Claim 2, wherein said valve is provided in a manifold on the corresponding unit.

4. A hydraulic control unit in accordance with Claims 1, 2 or 3, wherein there is provided a source of hydraulic fluid forming a continuous loop from which at least one of said at least two hydraulically operated rams takes a feed line to its hydraulic input.

5. A hydraulic control unit in accordance with any of the preceding claims, wherein said valve is operated by a solenoid, which solenoid is proximate to the corresponding valve.

6. A hydraulic control unit in accordance with Claim 6, wherein said solenoid is integral with the corresponding ram.

7. A hydraulic control unit in accordance with any of the preceding claims, wherein there is provided a return line forming a continuous loop and a spur extending to at least one of said at least two rams.

8. A hydraulic control unit, substantially as described herein and with reference to figures 1 and 3 of the drawings hereof.

9. A roof support arrangement comprising a hydraulic control system in 5 accordance with any of the preceding claims.