AU2013220787B2

AU2013220787B2 - Hydraulic circuit for longwall support

Info

Publication number: AU2013220787B2
Application number: AU2013220787A
Authority: AU
Inventors: Wilfried Weigel; Gerhard Wulfing
Original assignee: Tiefenbach Control Systems GmbH
Current assignee: Tiefenbach Control Systems GmbH
Priority date: 2012-02-18
Filing date: 2013-01-30
Publication date: 2016-12-08
Anticipated expiration: 2033-01-30
Also published as: WO2013120474A3; CN104169525B; CN104169525A; WO2013120474A2; AU2013220787A1; DE102013001581A1

Abstract

The invention relates to a hydraulic circuit for the longwall support in underground mining for supporting a longwall by means of a plurality of support shields, which hydraulic circuit comprises a pressure sensor (19) in the annular piston line (10) of each cylinder/piston unit (4). When a predetermined maximum pressure is reached, the pressure sensor (19) emits a pressure warning signal (28), by which the entire longwall can be depressurized by means of a longwall cut-off valve (11). The pressure warning signal (28) is locked with respect to any control signal for one of the hydraulic valves.

Description

2013220787 15 Nov 2016 1

Hydraulic Circuit for Longwall Support

TECHNICAL FIELD

[0001] The invention relates to a hydraulic circuit for supporting a longwall by means of a support device (support shield) in underground mining according to the preamble of Claim 1.

BACKROUND

[0002] A circuit of this type is known from PCT/DE2010/000685 = WO2011006461A2 (Claim 7). As a result of the pressure monitoring provided, unforeseen operating states are prevented, in which pressure conditions arise that are sufficient for hydraulic pilot control, i.e., for opening important valves, even in the event of disruptions of the pump system, and in the event of emergency shut-off of the entire electrical and hydraulic control, and also in the event of very high roof pressures that the load holding valves are unable to absorb.

[0003] In the embodiment of WO2011006461A2 according to Claim 7, the ring piston line of each cylinder/piston unit is also monitored by a pressure sensor. As a result of the pressure sensor, the entire longwall is depressurized when a pre-specified maximum pressure is reached, so that, in particular, the check valves holding the roof pressure can no longer be released. In such case, however, operating states may also arise, in which control of the system is necessary -whether it be by hand or automatic. It is desirable to design the hydraulic circuit in such a way that the system may be extensively monitored and any required control intervention remains possible. 2013220787 15 Nov 2016 2 [0003a] A reference herein to a matter which is given as prior art is not to be taken as an admission that the matter was known or that the information it contains was part of the common general knowledge as at the priority date of any of the claims.

SUMMARY OF THE INVENTION

[0004] According to the present invention there is provided a hydraulic circuit for longwall support for use in underground mining for supporting a longwall by means of a plurality of support shields where each support shield comprises: at least one hydraulic cylinder/piston unit configured to perform support functions such as removing timbering, progressing, and setting, wherein the at least one cylinder/piston unit is connected with a shield control valve by an unblockable check valve and a pressure line, wherein, upon demand by a shield control device that is assigned to each support shield, the at least one cylinder/piston unit is either connected by the shield control valve with a pump line, or when the check valve is simultaneously unblocked, is connected with a return line, or is blocked against the pressure line by the check valve, wherein an annular piston line of the at least one cylinder/piston unit is monitored by means of a pressure sensor which in turn activates a pressure deviation signal, when a predetermined maximum pressure is reached, which causes the hydraulic circuit to be depressurized by means of a longwall shut-off valve such that the check valve remains blocked, and wherein the pressure deviation signal is locked against a triggering signal of the shield control device such that the pressure deviation signal does not cause the longwall shut-off valve to become depressurized if the triggering signal is present.

[0005] In one embodiment there is provided a supplemental refinement, which makes possible a negative emergency operation, so to speak, that is, enables the control if, due to the pressure 2013220787 15 Nov 2016 2a signal of the pressure monitor according to Claim 1, an emergency signal would result in a system failure .

[0005a] Where the terms “comprise”, “comprises”, “comprised” or “comprising” are used in this specification (including the claims) they are to be interpreted as specifying the presence of the stated features, integers, steps or components, but not precluding the presence of one or more other features, integers, steps or components, or group thereto.

DETAILED DESCRIPTION

[0006] The invention is described below with reference to an exemplary embodiment. In so doing, express reference is made to the drawing description for Figures ΙΑ, IB and 2 of WO2011006461A2 and, in particular, for Figure IB and its description.

[0007] The terms and related reference numerals used are adopted in this application; differences are expressly mentioned in the following description of Figure 1 of this application.

[0008] The electrical/hydraulic circuit of a support shield in a longwall according to WO2011006461A2 includes the following elements, which are also depicted or indicated in the drawings.

[0009] The longwall supply line (pumps - collective line, supply), which extends over a portion of the longwall or over the entire length of the longwall, and which is connected to the pumping station - minus reference numeral. 2013220787 15 Nov 2016 2b [0010] The collecting return line 2 (return - collective line, return), which extends over a portion of the longwall or over the entire length of the longwall and is connected to the tank - minus reference numeral - of the pumping station. 3 [0011] The hydraulic control line of the shield control device for a support shield. One of the power sources 4 is shown. The hydraulic control device 3 is connected via the supply- branch line 12 to the supply and via the return - branch line 13 to the return.

[0012] A power source, depicted here as a cylinder/piston unit 4.

[0013] The electric control unit 5 of the shield control device for controlling the hydraulic control unit 3. The hydraulic control unit 3 and the electric control unit 5 together form the support control unit, which itself is configured for inputting switch and control commands, but which may also receive its control and switch commands from the central longwall control unit 15.

[0014] Auxiliary valves also present, in particular check valves, are not depicted or further described.

[0015] The hydraulic control unit includes multiple valves. In principle, the connection of each power source 4 to the pump collecting line of the longwall between the output of the power source loaded by the roof pressure and the hydraulic control device 5 is locked by a load holding valve 14 designed as a releasable check valve, so that if the pump pressure fails or is switched off, the load pressure of the power source directly impacts the tightly sealing check valve 14. This check valve 14 may be released by hydraulic pilot controlling as a result of the system pressure, if the pressure difference between load pressure and pilot control pressure falls below a value pre-specified by the design of the valve. The check valve 14 is hydraulically switched so 4 that when hydraulically released, the operating space of the power source is connected to the collective return line via outlet 6 and the branch return line. A releasable check valve of this type is known, for example, from DE 38 04 848 Al.

[0016] The pressure monitoring device 19 prevents the pressure between the releasable check valve 14 and the cylinder/ring-space or the hydraulic control unit 3 from reaching a level that may lead to an unintentional release (opening up) of the check valve 14 functioning as a load holding valve, see WO2011006461A2. Depicted in the detailed sketch according to Figure 1 are the individual valves of the hydraulic control unit 3.

[0017] The pilot control valve 16.1 for setting the power source and pilot control valve 16.2 for robbing the power source are controlled via bus line 20 by the electric control unit 5 of the support shield or by the central longwall control unit 15 via the signal line 21 and hydraulically switch the main valve 17.1 between the two positions for setting the power source and main valve 17.2 for robbing the power source.

[0018] By encoding the switch signals, the magnets of the pilot control valve are interlocked in the following manner: • during hydraulic control in the sense of setting (raising): o Main valve 17.1 opens the connection (branch supply line 12, setting-line 22) between longwall supply line (pump line, pressure line) 1 and power source input 6; 5 o Main valve 17.2 releases the connection (ring piston line 10, branch return line 13) of the ring space 24 to the collective return line 2. o The piston of the power source 4 and the load exerted thereon are raised. • during standstill: o Main valve 17.1 blocks the connection between terminal 6 of the power source and longwall supply line (pump line, pressure line) 1 and opens the connection to the collective return line 2 o Main valve 17.2 releases the connection of the ring space 23 to the collective return line 2. o The load exerted on the piston of the power source is maintained by the locked check valve 14/load holding valve. • during hydraulic control in the sense of robbing (lowering of the piston): o Main valve 17.1 blocks the connection between the longwall supply line (pump line, pressure line ) 1 and opens the connection to the collective return line 2 o Main valve 17.2 releases the connection of the ring space 23 to the longwall supply line (pump line, pressure line) 1. o The load exerted on the piston of the power source is maintained by the locked check valve 14/load holding valve, until the check valve 14 is released via the branch line 24 as a result of the rising pressure in the ring piston line 10. o The load exerted on the piston of the power source is reduced. 6 [0019] Standstill is a critical state, since there is personnel in the longwall that could be endangered by undesirable movements of the support devices. Such endangerment is avoided by the pressure sensor 19, which is switched into the ring piston line 10 of each cylinder/piston unit 4. Each of these pressure sensors 19 is connected via another bus line 20 to the longwall shut-off valve 11 via the central longwall control unit 15 in such a way that when a pre-specified maximum pressure in the ring piston line 10 is reached, the entire longwall may be depressurized. This also ensures that an inherent pressure, which could release the check valve that maintains the roof pressure, is no longer present. Thus, the permissible maximum pressure at which all support units of the long wall are depressurized, is clearly set, specifically, at least 20%, lower to 50 bar pressure, than the inherent pressure of, for example, 80 bar sufficient for releasing the check valve.

[0020] However, operating states may occur in which an intervention in the control is desirable or even necessary. For this reason, it is provided that the longwall system shut-off valve 11 is shut off only if no control signal for the main valves 16.1, 16.2 is present. For this reason, the central longwall control unit 15 is activated via an AND gate 26, which emits a positive output signal only if the pressure signal of the pressure sensor 19 is positive and, at the same time, the signal for controlling the pilot control valve 16.1, 16.2 is negative. This is depicted here by a negative (NAND) gate 26, which is connected to the signal line 21, and emits a positive output signal to the AND gate 25 of the longwall control unit 15 only in the event of a negative input signal. This prevents the pressure sensor 19 from intervening in an intended, operating state or movement sequence of the power source, whether controlled by hand or automatically. Such a situation could namely again become dangerous. 7 [0021] It is also provided that the function of the pressure sensor 19 may be switched off completely. A pushbutton switch 28, which is connected in the line between longwall control unit 15 and longwall shut-off valve 11, may be used for such purpose. If needed, this pushbutton switch may be opened if an unintended switch-off of the entire longwall is undesirable. It is equally possible to circumvent the pressure sensor by a circuit not depicted herein. 8

List of Reference Numerals 1. Longwall supply line 1 2. Collective return line 2 3. Shield control unit, hydraulic control unit, shield control valve, control block 3 4. Power source, cylinder/piston unit 4 5. Electric control unit, shield control unit 5 6. Pressure line, output, outlet 6 7. Pressure monitoring device, pressure sensors 7 8. Monitoring unit, monitoring component 8 9. Monitoring bus line 9 10. Ring piston line 11. Longwall shutoff valve, shield control unit 11 12. Branch supply line 12 13. Branch return line 13 14. Load holding valve, releasable check valve 15. Central longwall control unit 15 16. Pilot control valve 16 17. Main valve 17 18. Pressure safety valve 18 19. Pressure sensor 20. Bus line 20 21. Signal line, control signal 21 9 22. Setting line 22 23. Ring space 23 24. Branch line 24 25. AND gate 25 26. Negative (NAND) gate 27. Pushbutton switch 27 28. Pressure warning signal 28

Claims

The Claims defining the invention are as follows:

1. A hydraulic circuit for longwall support for use in underground mining for supporting a longwall by means of a plurality of support shields where each support shield comprises: at least one hydraulic cylinder/piston unit configured to perform support functions such as removing timbering, progressing, and setting, wherein the at least one cylinder/piston unit is connected with a shield control valve by an unblockable check valve and a pressure line, wherein, upon demand by a shield control device that is assigned to each support shield, the at least one cylinder/piston unit is either connected by the shield control valve with a pump line, or when the check valve is simultaneously unblocked, is connected with a return line, or is blocked against the pressure line by the check valve, wherein an annular piston line of the at least one cylinder/piston unit is monitored by means of a pressure sensor which in turn activates a pressure deviation signal, when a predetermined maximum pressure is reached, which causes the hydraulic circuit to be depressurized by means of a longwall shut-off valve such that the check valve remains blocked, and wherein the pressure deviation signal is locked against a triggering signal of the shield control device such that the pressure deviation signal does not cause the longwall shut-off valve to become depressurized if the triggering signal is present.
2. The hydraulic circuit according to claim 1, wherein the pressure deviation signal can be deactivated manually or the pressure sensor can be bypassed.