US3564974A

US3564974A - Pressure-fluid systems

Info

Publication number: US3564974A
Application number: US802507*A
Authority: US
Inventors: Reginald Hector Painter
Original assignee: Gullick Ltd
Current assignee: Gullick Ltd
Priority date: 1968-03-22
Filing date: 1969-02-26
Publication date: 1971-02-23
Anticipated expiration: 1988-02-23
Also published as: DE1910505B2; DE1910505A1; GB1233188A

Abstract

The invention is a pressure-fluid system, comprising at least two pressure-fluid-operated devices, in which means is provided whereby when said devices are exhausting simultaneously the exhaust from one is prevented from affecting the desired operation of the other. One particular application of the invention is to self-advancing or walking mine roof supports in which the two pressure-fluid-operated devices are respectively the leg or prop means and the advancing ram of the support. The invention is particularly applicable where both pressure-fluidoperated devices are controlled from a single selection or control valve.

Description

United States Patent Reginald Hector Painter Ripley, England 802,507

Feb. 26, 1969 Feb. 23, 1971 Gullick Limited Wigan, England Mar. 22, 1968 Great Britain Inventor Appl. No. Filed Patented Assignee Priority PRESSURE-FLUID SYSTEMS 9 Claims, 8 Drawing Figs.

Int. Cl FlSb 11/16 Field of Search 91/413, 411, 4.04, 170 (MP); 60/97 (L), 97 (E) [56] References Cited UNlTED STATES PATENTS 1,824,062 9/1931 Winter 91/413X 2,416,373 2/1947 Brown 91/413 3,039,266 6/1962 Schenkelberger 60/97EX Primary ExaminerEdgar W. Geoghegan Att0rneylmirie and Smiley ABSTRACT: The invention is a pressure-fluid system, comprising at least two pressure-fluid-operated devices, in which means is provided whereby when said devices are exhausting simultaneously the exhaust from one is prevented from affecting the desired operation of the other. One particular application of the invention is to self-advancing or walking mine roof supports in which the two pressure-fluid-operated devices are respectively the leg or prop means and the advancing ram of the support. The invention is particularly applicable where both pressure-fluid-operated devices are controlled from a single selection or control valve.

PATENTED FEBZSIQ?! v I 1 35641974 SHEET 2 BF 4 INVENTOR:

REGINALD H. PAINTER PRESSURE-FLUID SYSTEMS This invention is for improvements in or relating to pressure-fluid systems and particularly hydraulic systems in which a number of devices in hydraulic circuits perform operations together and are controlled from a central control. With such systems there is the problem, when two or more of the circuits are open to common exhaust system, that fluid may be directed from one functional line or circuit to the other. This has the effect of operating one of the functions in reverse, i.e. the functioning device is fed with pressure-fluid whereas it is intended that it should be exhausting.

One particular application of the invention which is mentioned by way of example, is to self-advancing hydraulic mine roof supports of the well known kind comprising one or more hydraulically extendible legs or props and a hydraulic advancing ram. In this case the aforementioned problem is that when the props or legs are connected to exhaust, so as to release the support from between mine floor and roof, fluid-pressure is also exhausted from one side of the advancing ram as it is operated to advance the support. As a result pressure-fluid exhausted from the ram may be fed to the props or legs and said props or legs may be reset to the roof. Thus, the intended advance of the support is prevented. An object of the present invention is to overcome this problem.

According to the present invention there is provided a pressure-fluid system comprising at least two pressure-fluidoperated devices wherein means is provided whereby when said devices are exhausting simultaneously the exhaust from one is prevented from affecting the desired operation of the other.

The two pressure-fluid-operated devices may, for example, be the hydraulic advancing ram of a self-advancing or walking mine roof support.

In one preferred arrangement according to the invention means is provided whereby the exhaust from one of the devices is caused to bypass a control or selection valve of the system by which operation of the devices is controlled or selected.

The pressurizing of one of the fluid-operated devices may be caused to influence the state of the other fluid-operated device by connecting said device to exhaust. If the back pressure in the exhaust line to one device is excessive a further exhaust line may be provided together with a device which, under such excessive pressure, operates to direct the exhaust of one device to a secondary return line.

One particular embodiment of the invention will now be described, by way of example, as applied to a self-advancing hydraulically-operated mine roof support. In the following description reference is made to the accompanying drawings in which:

FIG. 1 is a perspective view of the roof support,

FIG. 2 is a diagram of the hydraulic system,

FIG. 3 is a cross section on the line III-III of FIG. 4 of a control or selection valve embodied in the system,

FIG. 4 is a cross section on the line IV-IV of FIG. 3,

FIG. 5 is a perspective view of a rotary valve element of the valve shown in FIGS. 3 and 4,

FIG. 6 shows the relative positions of the ports in the control or selection valve when the ram of the support is being operated to push a conveyor towards the mineral face,

FIG. 7 shows the relative positions of the ports in the control or selection valve when said ram is being operated to pull the support towards the mineral face, and

FIG. 8 shows the relative positions of the ports in the control or selection valve when pressure fluid is being supplied to the props or legs of the support to extend them and secure the support between floor and roof.

The support, shown in FIG. 1, is of the well known kind comprising one or more hydraulically extensible telescopic legs or props 10 and a hydraulic double-acting advancing ram 11. Advance of the support may, for example, be effected by utilizing the ram 11 to advance a coal face conveyor C and then, retracting the ram to advance the support, the piston of the ram being anchored to the conveyor and the support being temporarily released from between floor and roof.

The hydraulic system for the props 10 and the ram 11 comprises a hydraulic supply line 12 and exhaust lines 13 and 14.

The supply to and exhaust of hydraulic fluid from the props 10 and the ram 11 is controlled from a central position by means of a rotary control or selection valve 15 having a port 16 connected to the props 10, a port 17 connected to a port 11a on the retract side of the ram 11, a port 18 connected to the exhaust line 13 and a port 19 connected, via a shuttle valve 20, to a port 11b on the advance side of the ram 11. The port 11b of the ram 11 is also connected, via the shuttle valve 20 and a nonretum valve 21, to the exhaust line 14.

The selection valve 15 has a fluid-tight casing or chest 15a and a rotor iSb provided with a port 22, for connecting the supply 12 with the selected port l6, 17 or 19, and with a cavity 23 of elongated form in its underface.

As shown in the diagram (FIG. 2) and in FIGS. 3 and 4, the selection valve 15 is in a neutral position, i.e. the port 22 does not register with any of the

ports

16, 17 or 19 and the port 16 is connected, via the cavity 23 and port 18 to the exhaust line 13.

When it is required to advance or extend the ram to push the conveyor C towards the mineral face, the control valve 15 (see FIG. 6) is turned so as to bring the feed port 22 into register with the port 19 and connect the port 11b of the ram to the supply 12 and the port lla'to the exhaust line 13 via the port 17, cavity 23 and port 18. During this stage the shuttle valve 20 is depressed so as to open the connection to the port 11b of the ram and close the connection from the port 11b to the exhaust line 14.

When it is required to retract the ram so as to advance the support, to which the cylinder of the ram is connected, the selection valve 15 (see FIG. 7) is turned into a position in which the port 22 registers with the port 17 so that the port 11a on the retract side of the ram 11 is connected to the supply 12. In this position of the control valve the props 10 are connected, via the cavity 23, to the exhaust line 13 and the port 11b on the advance side of the ram is connected via the shuttle valve 20 (which is in the position shown in FIG. 2) and the nonretum valve 21, to the exhaust line 14. During this stage the shuttle valve is raised so as to block off any connection via the port 19 to the props or legs 10. Thus, the exhaust from the advance or right hand side of the ram (i.e. from the port 11b) cannot act on the props 10 to interfere with the required lowering of the latter to enable the support to advance.

With arrangements as adopted heretofore, during retraction of the ramll, pressure fluid exhausted through the ports 11b and 19 to the return line 13 interfered with the lowering of the props or legs 10 of the support and with the advance of the latter. With the arrangement according to the present invention, however, despite the fact that both the legs 10 and the ram 11 are controlled from the same valve 15, pressure-fluid discharging through the port 11b is prevented by the shuttle valve 20 from acting on the legs or props 10 of the support and is bypassed via the valves 20 and 21, to the secondary return line 14.

To extend the legs and reset the support between floor and roof, after it has been advanced, the rotor 15b of the control valve is turned to the position shown in FIG. 8 in which the port 16 registers with the port 22 and thereby communicates, via the casing 15a, with the pressure fluid supply port 12, the retract side of the ram 11 being connected via the port 17, cavity 23 and port 18 to the exhaust line 13 ready for the next conveyor advancing stroke of the ram.

The system may be modified by combining the return lines 13 and 14 particularly if the back pressure is relatively small.

It will be understood that in known systems the valve 15 controls the legs or props 10 of the support as well as the advancing ram 11 and all fluid, both feed and exhaust, for all functions of the roof support, passes through this valve whereas, with the arrangement according to the invention fluid exhausted from the ram via the port 11b is caused to bypass the valve 15.

I claim:

1. A pressure fluid system comprising at least two pressure fluid operated devices and means which is operative, when said devices are exhausting simultaneously, to prevent the exhaust from one device affecting the desired operation of the other device, wherein said means is a pressure sensitive valve in a connection between one of said pressure fluid operated devices and an operation-selection valve for the devices and an exhaust line, said pressure sensitive valve being operative to close said connection said selection valve and open the connection to said exhaust line when said one pressure fluid operated device is exhausted through said connection.

2. A system as claimed in claim 1 wherein said pressure sensitive valve is a shuttle valve.

3. A system as claimed in claim 1 wherein a nonreturn valve is provided in said connection between said pressure sensitive valve and said exhaust line.

4. A system as claimed in claim 1 wherein both pressure fluid operated devices are controlled from a single operation selection valve.

5. A system as claimed in claim 1 wherein there are two exhaust lines one for one of said pressure-fluid-operated devices and one for the other of said pressure fluid operated devices.

6. A system as claimed in claim 1 wherein said operationselection valve has a cavity and a plurality of ports arranged so as to be connected selectively by relative movement between them and said cavity.

7 A system as claimed in claim 1 wherein the two pressurefluid-operated devices are respectively the hydraulically extensible prop means and the hydraulically operated advancing rarn of a self-advancing mine roof support.

8. A system as claimed in claim 1 wherein the two pressure fluid-operated devices are respectively the hydraulic prop means and the double acting hydraulic advancing ram of a self-advancing mine roof support and wherein a single operation-selection valve controls the operation of said prop means and said ram and wherein a shuttle valve controls connections between said operation-selection valve, the side of said ram, which is exhausted during advance of the support, and an exhaust line, the arrangement being such that when pressure fluid is being exhausted from said side of the ram the operation-selection valve is isolated from that side of the ram.

9. A system as claimed in claim 8 wherein there is nonreturn valve between said shuttle valve and said exhaust line.

Claims

6. A system as claimed in claim 1 wherein said operation-selection valve has a cavity and a plurality of ports arranged so as to be connected selectively by relative movement between them and said cavity.

7. A system as claimed in claim 1 wherein the two pressure-fluid-operated devices are respectively the hydraulically extensible prop means and the hydraulically operated advancing ram of a self-advancing mine roof support.

8. A system as claimed in claim 1 wherein the two pressure-fluid-operated devices are respectively the hydraulic prop means and the double acting hydraulic advancing ram of a self-advancing mine roof support and wherein a single operation-selection valve controls the operation of said prop means and said ram and wherein a shuttle valve controls connections between said operation-selection valve, the side of said ram, which is exhausted during advance of the support, and an exhaust line, the arrangement being such that when pressure fluid is being exhausted from said side of the ram the operation-selection valve is isolated from that side of the ram.