GB2077472A

GB2077472A - Improvements relating to control devices

Info

Publication number: GB2077472A
Application number: GB8111914A
Authority: GB
Original assignee: RICH ROY SERVICES Inc
Current assignee: RICH ROY SERVICES Inc
Priority date: 1980-04-24
Filing date: 1981-04-15
Publication date: 1981-12-16
Also published as: GB2077472B

Abstract

A control device, for use in a control system, e.g. of the kind used to control underground coal mining conveyor systems; comprises control members 12, (14) (not shown) each of which is adapted to be secured to a respective elongate control element 18, 20 such as a pull wire. Each of the control members is thus urged in one direction by the respective control element, and is urged in the opposite direction by a respective spring 16. The control device also comprises a switch mechanism 28 adapted to be actuated by movement of either of the control members 12, (14) whether in consequence of movement of either of the control members in the one direction in consequence of an increase in the tension in the respective control element, or in the opposite direction in consequence of a decrease in the tension in the respective control element. The control device also comprises a signalling switch 52 which is manually operated to signal to a control centre, independently from actuation of the switch mechanism 28. <IMAGE>

Description

SPECIFICATION Improvements relating to control systems Description of Invention This invention is concerned with improvements relating to control systems, as are used to control the operation of ancilliary apparatus. The invention will particularly be described in the context of the underground mining of coal, but it is to be appreciated that the invention is not limited to this context, and may be used in the control of apparatus in other fields.

In the underground mining of coal, a complex conveyor system is utilised to convey coal from the mine working to the surface. This involves complicated inter-relationships between the individual conveyor units, some of which may travel distances of one or more miles. It has therefore become the practice, to install alongside the main conveyor, at spaced intervals, control devices whereby an operative may temporarily or permanently stop the operation of the main conveyor, and (where necessary) stop the operation of associated conveyors.

Thus a conventional control system comprises a plurality of control devices, located at spaced intervals along the length of the main conveyor, and which are connected back to a control unit, which may be a local control unit, controlling operation of the conveyor or associated machinery, such as a rope haulage machine, orto a control centre exercising a controlling function over various aspects of the mining operation. Each control device comprises a manually operable switch member, depression of which by an operative causing operation of the conveyor to be terminated.

Additionally, since it may be necessary for an operative to stop the conveyor from any point along its length, conventionally the control devices are interconnected by elongate elements, conventionally in the form of control wires arranged in a manner such that the switch member may be actuated by the operator pulling on the control wire.

In this manner, an operative may stop operation of the conveyor anywhere along its length.

It is additionally conventional practice for the control devices to comprise signalling means, whereby simultaneous with operation to stop the conveyor, a signal may be sent to the control centre, identifying for example the reason for the operative taking action. Such signalling is conventionally effected, either by pulling on the control wire in code, or by repeated depression of the switch member, in code.

One of the problems encountered in existing control systems, is that the control wires may break, or become fouled, rendering them difficult or impossible to actuate.

Another of the problems encountered in conventional control systems is that their versatility is limited. For example, no existing system permits an operative to signal back to the control centre, without interfering with the operation of the conveyor.

According to a first aspect of this invention there is provided a control device, adapted for use with an elongate control element adapted to be secured to the device under tension, the control device comprising a housing, a control member to which the control element is in the use of the device connected in a manner whereby tension in the control element urges the control member in a first direction, resilient means to urge the control member in a second direction in opposition to the first direction, and switch mechanism adapted to be actuated in consequence of movement of the control member in either of the fi rst or the second directions.

Thus, where the control device is used to control operation of anciliary apparatus, e.g. to stop the apparatus, the switch mechanism may be interposed in circuitry controlling the apparatus, or may be interposed in a circuit branch extending back to a control centre, being operative either automatically or by the intervention of a control operative, to stop the apparatus. Thus the switch mechanism may be actuated to stop the apparatus either by movement of the control member in the first direction, as may be effected by increasing the tension in the control element, or by said resilient means.

Thus, the switch mechanism will be actuated by manual pulling of the control element, and will also be actuated in the event of a failure of the control element, such as by breakage thereof, or other reduction in the tension thereof, under the action of said resilient means. Preferably the control device comprises means to retain the switch mechanism actuated, for example when the control element has been released by an operative.

Preferably the control member is in the form of a cam, provided with a cam surface, and the control device comprises an actuating member, adapted to actuate the switch mechanism, and which is connected to a cam follower which is in engagement with the cam surface, movement of the cam follower being caused by movement of the cam. Preferably the cam follower is resiliently urged into engagement with the cam surface, such as by a spring.

Preferably the control device comprises a manually-operable switch member, whereby the switch mechanism may be actuated directly by an operative. Conveniently the switch member comprises means to retain it in an operative position, once it has been actuated.

Conveniently the switch member is connected to the actuating member, whereby the same means may be used to retain the switch mechanism actuated, whether actuation is effected by movement of the control member, or manual actuation of the switch member.

However, if desired, the construction and arrangement may be such that, upon restoration of the control member to its rest position subsequent to actuation thereof by the control element, the switch mechanism returns to its rest position, whereas upon release of the switch member subsequent to manual actuation thereof, the switch mechanism is retained in its actuated position.

The control member may be mounted in the housing for rotary movement, being urged in one rotary direction by the tension in the control ele ment, and being urged in the opposite rotary direction by the resilient means. Preferably however the control member is mounted in the housing for linear movement in the first and second directions from a rest position, determined by a balance in the forces applied thereto by the elongate control element and the resilient means.

Preferably the control device comprises a second control member to which a second control element may be connected in a manner whereby the tension in said second control element urges said second control member in one direction, resilient means being provided to urge said second control member in an opposite direction, the or further switch mechanism of the control device being adapted to be actuated in consequence of movement of the said second control member in either of said directions thereof.

Where the first control member is mounted for rotary movement, most conveniently the second control member is also mounted for rotary movement. Said two control members may for example be mounted for rotary movement about a common axis, said one direction of the second control member being rotary movement in one direction about the axis, corresponding to rotary movement of the first control member in said second direction.

Alternatively the two control members may be provided by an assembly mounted integrally for rotary movement about an axis, tension in either of the control elements urging the assembly in one rotary direction (i.e. first control member in said first direction and second control member in said one direction) and the resilient means urging the assembly in the opposite rotary direction (i.e. first control member in said second direction and the second control member in said opposite direction.

Preferably however both control members are mounted in the housing for linear movement, said one direction of the second control member corresponding to the second direction of the first control member, and the said opposite direction of the second control member corresponds to the first direction of the first control member.

In this manner, an elongate control element will be connected to the first said control member, extending from the housing in one direction, and a second control element will be connected to the second control member, extending from the housing in the opposite direction.

Most conveniently the control device comprises a single switch mechanism adapted to be actuated by movement of either of said control members, in response to an increase or decrease in the tension of either of the elongate control elements.

According to another aspect of this invention there is provided a control device, adapted for use with an elongate control element secured thereto under tension, the device comprising a control switch which may be operated either by an alteration of the tension in the control element, or by manual operation of the control switch, wherein the control device comprises a signalling switch which may be operated manually, in isolation from the control switch, to transmit a signal to the control centre controlling the operation of the ancilliary apparatus.

In this manner, an operative tending to or being in the vicinity of said ancilliary apparatus may signal, e.g.(in code) to the control centre, without it being necessary to interfere with the continuing operation of the ancilliary apparatus.

Preferably the control device set out in the last preceding paragraph but one also comprises the features set out in any one of the last preceding paragraphs but two, to the last preceding paragraph but thirteen.

There will now be given a detailed description, to be read with reference to the accompanying drawings, of part a control system which is a preferred embodiment of this invention, and which has been selected to illustrate the invention by way of example.

In the accompanying drawings: Figure 1 is a schematic elevational view showing the control device which is the preferred embodiment of this invention in position on an upright post; Figure 2 is a first vertical sectional view of the control device taken along the line ll-ll of Figure 1; Figure 2a is a view of a modified part of the preferred embodiment; and Figure 3 is a second vertical sectional view of the control device, taken in a plane extending at right angles to that of the section shown in Figure 2.

The control device which is the preferred embodiment of this invention is adapted to be mounted at any convenient position alongside a conveyor roadway in an underground mine working, where it constitutes part of a system comprising a number of such control devices mounted at spaced intervals along the length of the roadway. In the preferred embodiment, the control devices are shown mounted on upright posts 6, but it is to be appreciated that they may be located in their desired positions by other means, such as by bolting to the roadway rings. The control device comprises a housing 8, and two generally cylindrical, elongate control members 12, 14 mounted side by side in a compartment 10 of the housing.Each of the control members 12, 14 affords a linear cam, and they are urged in opposite directions by resilient means, provided by springs, only one of which, numeral 16 in Figure 3, being shown. Each of the control members is adapted to be connected to an associated elongate control element, afforded by one of the control pull wires 18, 20, the tension in said pull wires urging the control members 12 and 14 in directions opposite to those in which they are urged by their associated springs.

The control member 12 is provided with a single V-shaped cam surface 22, and a cam surface 24 of single slope, inclined to the direction of the pull wire 18 (direction A). The control member 14 is provided with a cam surface (not shown) similar to the cam surface 22, and which, when the control device is at rest, will be in a position corresponding to (i.e.

alongside) that adopted by the cam surface 22.

Additionally however the control member 14 comprises a cam surface 26 of single slope, inclined to the direction of the pull wire 20: At rest, the cam surface 26 will adopt the position shown in dotted lines in Figure 3.

The control device comprises a switch mechanism comprising six microswitches a, b, c, d, e, and f. The switch mechanism also comprises a control switch comprising a switch member 28 in the form of a mushroom-shaped plastics moulding, said switch member being urged by a compression spring 30 into its inoperative position, as is shown in Figure 2.

A stem 32 of the switch member is hollow and connected within the hollow stem by an elongate actuating member 34 is the stem 36 of a cam follower 38 which is bifurcated, having arms 40 which are located within the V of the cam surface 22 of the control member 12, and and within the V of the corresponding cam surface of the control member 14.

In the position shown in Figure 2, with the switch member 28 in its inoperative position, the actuating member 34 is spaced from the microswitches a, b, c, and d.

The position adopted by the control members 12 and 14 is determined by the balance between the tension exerted thereon in a first direction by the pull wire, and the tension exerted thereon in the opposite direction by the associated compression spring, and at rest the position of the control members will be such that the arms 40 of the cam follower 38 will be located in the root of the cam surface 22, and in the root of the corresponding cam surface of the control member 14.

However in the event of an increase in the tension in the pull wire 18, the control member 12 will move in a first direction (A, Figure 3) causing the arm 40 of the cam follower 38 to ride up one side of the cam surface 24, pulling the switch member 28 downwardly, and the actuating member 34 towards the microswitches a, b, C and d. Alternatively, an increase in the tension of the pull wire 20 will cause the other arm to rise up one side of the corresponding cam surface of the control member 14, similarly causing the actuating member to approach the microswitches a, b, c and d.

Thus the four microswitches a, b, c and d may be actuated by an operative exerting adequate tension on either of the pull wires 18 and 20. The microswitch a may be effective to stop the ancilliary apparatus (e.g. conveyor), the microswitch b may be operative to stop associated apparatus (e.g. conveyors feeding the ancilliary conveyor), the microswitch c may signal back to the control centre that this control device has been actuated, and the microswitch d may be utilized for any other purpose.

The switch mechanism also comprises means 42 comprising a spring urged ball which is adapted to be received within a circumferential groove 44 of the stem of the switch member 28, which is operative to hold the switch member 28 in its actuated position, and to retain the actuating member 34 in engagement with the microswitches a, b, c and d until a deliberate releasing action is taken.

However alternate to actuation of the control device by an increase in the tension on either of the pull wires 18 and 20, should the tension on either of the pull wires decrease significantly, as may occur if there is a breakage in either of the pull wires, the control members 12 and 14 will move in their opposite directions, under the action of their associated springs, similarly causing actuation of the control device, the first said arm 14 of the cam follower 38 riding up the opposite side of the cam surface 24, or the said other arm 40 riding up the opposite side of the corresponding cam surface of the control member 14.

Alternate to actuation of the control device being caused by an increase or decrease in the tension of either of the pull wires 18 and 20, the control device may be similarly actuated by manual depression of the switch member 28.

The control device which is the preferred embodiment of this invention additionally comprises a signalling switch 50, which comprises a switch member 52 to which a cam follower 54 (similar to the cam follower 38) is secured by an actuating member 56. The cam follower 54 is similarly provided with bifurcated arms, and in the rest positions of the control members 12 and 14, these arms seat at the root of the cam surface 24 of the control member 12 and at the root of the cam surface 26 of the control member 14. Thus, movement of either of the control members 12 or 14, as may be effected by pulling of either of the pull wires 18 and 20, causes a similar movement of the actuating member 56 towards and into engagement with the microswitches e and f.

Thus, an operative may pull the control wire 18, moving the control member 12 to cause actuation of the switch member 28, actuating the microswitches a, b, c and d, and to cause actuation of the switch member 52, actuating the microswitches e and f.

Subsequent to such action, which locks out the associated conveyor, the operative may release the pull wire 18, allowing the actuating member 56 to separate from the microswitches e and f, whilst the switch member 28 is retained actuated by the means 42. The operative can then repeatedly pull the wire 18, moving the actuating member 56 towards and into contact with the microswitches e and f, to send a coded signal back to the control centre.

However, if it is not necessary for the operative to stop the conveyor, he may merely send a coded signal back to the control centre by manual depression of the switch member 52, without interfering with the operation of the ancillary apparatus.

In the construction which is the preferred embodiment of this invention, the actuating member 34 passes through radial bores in the hollow stem 32 of the switch member, and through a bore in the stem 36 of the cam follower 38. Thus, movement of the cam follower 38 necessarily causes movement of the switch member 28. However, in an alternative construction, which may be utilised if desired, the actuating member 34 may pass through open slots in the stem 32 of the switch member, as is shown in Figure 2a. In this construction, actuative movement of the member 34 is permitted without causing movement of the switch member 28. In this manner, an operative may cause temporary actuation of the microswitches a, b, c and d by pulling of the wires 18 and 20, which will be released when the tension on the pull wire is released. However, permanent actuation of the microswitches, a, b, c and d may be caused by manual depression of the switch member 28, by virtue of said means 42.

Claims

1. A control device, adapted for use with an elongate control element adapted to be secured to the device under tension, the control device comprising a housing, a control member to which the control element is in the use of the device connected in a manner whereby tension in the control element urges the control member in a first direction, resilient means to urge the control member in a second direction in opposition to the first direction, and switch mechanism adapted to be actuated in consequence of movement of the control member in either of the first or the second directions.

2. A control device according to Claim 1 comprising retention means to retain the switch mechanism actuated, for example when the control element has been released by an operative.

3. A control device according to Claim 2 wherein said retention means is manually releasable.

4. A control device according to any one of the preceding claims wherein the control member is in the form of a cam, provided with a cam surface, and the control device comprises an actuating member, adapted to actuate the switch mechanism, and which is connected to a cam follower which is in engagement with the cam surface, movement of the cam follower being caused by movement of the cam.

5. A control device according to Claim 4 wherein the cam follower is resiliently urged into engage mentwith the cam surface.

6. A control device according to any one of the preceding claims comprising a manually-operable switch member whereby the switch mechanism may be actuated directly by an inoperative.

7. A control device according to Claim 6 wherein the switch member comprises means to retain it in an operative position, once it has been actuated.

8. A control device according to Claim 7 as appendantto Claim 4, wherein the switch member is connected to the actuating member whereby the same means may be used to retain the switch mechanism actuated, whether actuation is effected by movement of the control member, or actuation of the switch member

9. A control device according to Claim 7 wherein the construction and arrangement is such that, upon restoration of the control member to its rest position subsequent to actuation thereof by the control element, the switch mechanism returns to its rest position, whereupon release of the switch member subsequent to manual actuation of the switch member, the switch mechanism is retained in its actuated position.

10. A control device according to any one of the preceding claims, comprising a second control member to which a second control element may be connected in a manner wherebythe tension in said second control element urges said second control member in one direction, resilient means being provided to urge said second control member in an opposite direction, the or further switch mechanism of the control device being adapted to be actuated in consequence of movement of the said second control member in either of said directions thereof.

11. A control device according to Claim 10 wherein said one direction corresponds to the second direction of the first control element, and said opposite direction corresponds to the first direction of the first control member.

12. Acontrol device according to Claim 11, comprising a single switch mechanism which is adapted to be actuated by movement of either of said control members, in response to an increase or to a decrease in the tension of either of the elongate control elements.

13. A control device according to any one of the preceding claims, wherein the or each control member is mounted in the housing for rotary movement, being urged in one rotary direction by the tension in the control element, and being urged in the opposite rotary direction by the resilient means.

14. A control device according to Claim 13, as appendant to Claim 10 wherein the control members are afforded by part of an integral control assembly mounted in the housing for rotary movement, tension in either of the control elements urging the assembly in one rotary direction, being movement of the first control member in said first direction and the second control member in said one direction, and the resilient means urging the assembly in the opposite rotary direction, being movement of the first control member in said second direction and the second control member in said opposite direction.

15. A control device according to any one of Claims 1 to 12 wherein the or each control member is mounted in the housing for linear movement in said first and second directions from a rest position.

16. A control device, adapted for use with an elongate control element adapted to be secured under tension, the device comprising a control switch which may be operated either by an increase or a decrease in the tension in the control element, or by manual operation of the control switch, wherein the control device comprises a signalling switch which may be operated manually in isolation from the control switch, to transmit a signal to the control centre controlling the operation of the ancillary apparatus.

17. A control device according to Claim 16 wherein said signalling switch is adapted to be i operated to transmit a signal to the control centre in consequence of an increase in the tension in the control element, but not in consequence of a decrease in the tension in the control element.

18. A control device according to one of Claims 16 and 17, also comprising features set out in any one of Claims 1 to 13.

19. A control device constructed and arranged substantially as hereinbefore described with reference to the accompanying drawings.

20. Any novel feature, or any novel combination of features hereinbefore described and/or illustrated in the accompanying drawings.