AU759965B2 - Shuttle car cable protection system - Google Patents

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT Name of Applicants: Address for Service: Invention Title: PAUL RONALD ZETTL and PETER KARL ZETTL CULLEN CO., Patent Trade Mark Attorneys, 240 Queen Street, Brisbane, QId. 4000, Australia.

SHUTTLE CAR CABLE PROTECTION SYSTEM Details of Associated Provisional Application: Nos. PP1967 filed 24 February 1998 The following statement is a full description of this invention, including the best method of performing it known to us.

SHUTTLE CAR CABLE PROTECTION SYSTEM BACKGROUND OF THE INVENTION This invention relates to a protection system for a shuttle car. In particular, the invention relates to a protection system for protecting a cable supplying power to a shuttle car.

The shuttle car in relation to which the invention will be described by way of example normally operates in an underground mine. Such cars are used for transporting coal or other payload from one location to another. Such cars have an electric traction drive for driving the vehicle and other functions of the vehicle are hydraulically controlled via a hydraulic pump which is electrically driven.

*Electrical power is supplied to the car via a cable typically several hundred metres in length and which carries 100V. The car has a cable reel which is hydraulically operated to pay out and reel in the cable as the car travels through a mine.

The reel is located in a reel compartment and that compartment must be periodically checked for loose components, the reel must be checked for excessive play in the spooling device which forms part of the reel and correct reel 20 tension must be maintained and the compartment must be kept free of debris.

The reel includes a spooling shaft and a shuttle with a cable guide.

The shuttle together with the guide move back and forth above the spooling shaft to ensure that the cable is neatly layered onto the reel when it is reeled in and to ensure that it is neatly pulled out from the reel.

At present the car operator must exercise due care to ensure that the reel is rotating, that the cable is not subjected to excess tension and that the cable is not subjected to overrun when being wound up onto the reel. When overrun occurs, slack cable remains on the ground and there is a danger of the shuttle car running over the cable and the cable may be damaged.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a protection system for protecting a cable supplying power to a shuttle car which at least minimises Z e disadvantages referred to above.

3 According to an aspect of the present invention there is provided a protection system for protecting a cable which supplies power to a shuttle car and which is wound round or unwound from a rotatable cable reel mounted on the car when the car moves, the system including a detecting means operable to detect whether or not the reel rotates at a rate which exceeds a predefined threshold value, and a control means communicating with the detecting means and operable to inhibit movement of the car and rotation of the reel in response to the detecting means detecting that the rate of rotation of the reel does not exceed the threshold value so that the cable is thereby prevented from becoming excessively slack or excessively taut.

Preferably, the detecting means includes a pulse generator which is operable to output a pulse during each rotation of the reel such that the rate at which the pulses are generated is proportional to the rate of rotation of the reel.

The detecting means may also include a first timer which is operable to time the interval between successive pulses, and the control means may be operable to inhibit movement of the car and rotation of the reel if the time interval between the pulses exceeds a predefined value. The detecting means may also include a second timer which is operable to time the duration of the pulses, and the control means may be operable to inhibit movement of the car and rotation of the reel if the duration of a pulse exceeds a predefined value. The detecting means may be operable to detect whether or not the reel rotates at a rate which exceeds the predefined threshold value after a driver initiates movement of the car.

The control means may be operable to inhibit movement of the car by causing a speed regulator of the car to be switched off or by causing a breaking mechanism of the car to stop the car. The control means may be operable to inhibit rotation of the reel by causing a pump associated with the reel to stop.

S•Preferably, the protection system includes an alarm device which is ooo* operable to output an alarm signal in response to the control means inhibiting movement of the car and rotation of the reel.

BRIEF DESCRIPTION OF THE DRAWINGS A particular preferred embodiment of the invention will now be ,S ,escribed with reference to the drawings in which: 3a Figure 1 is a diagram of a shuttle car cable protection system according to an embodiment of the invention; Figure 2 is a diagram of a siren and indication circuit which may be used in conjunction with the system of Figure 1; and Figure 3 is a diagrammatic view of a shuttle car fitted with the system of the invention.

DESCRIPTION OF PREFERRED EMBODIMENT The operation of the system of Figure 1 controls the drive of a shuttle car for use in a mine such as a coal mine. Such shuttle cars are well known in the mining industry and are used to transport coal away from a coal face or seam in an underground mine. The car is a heavy duty unit designed to carry a payload such as coal or other material. The car has four wheel positive drive and four wheel hydraulic servo operated steering. A chain and flight conveyor driven at a discharge end may be elevated by hydraulic cylinders to discharge the payload. A hydraulic pump driven by an electric motor powers a cable reel, steering and conveyor functions. Two wheels on each side of the car are driven by separate traction motors through appropriate gearing. Rear drive units are coupled to similar units at the front of the car. Power is supplied to the car by an electric cable of a suitable length, typically about 200m and a take up reel for the cable is carried by the car.

20 As the car progresses through a mine the cable is either paid out from or retrieved and wound onto the reel. It is important that the cable is not damaged by the vehicle as the vehicle moves in the mine. The system of the invention provides and automatic way of controlling the car and the operation of the reel to ensure that the cable is not damaged.

The system includes a plurality of relays, timers and controlled contacts which together with the car drive controls ensure that the cable is paid out at a desired rate as the car travels in one direction and that the cable is rewound onto the reel when the car travels in the opposite direction.

The system is supplied with power, typically 110V. A protection on/maintenance/reset switch allows the system to be energised. When this reset switch is closed and a pump start switch is closed, a trip relay TR is energised and normally open contacts TR1, TR2 and TR3 of the relay, TR, are then closed.

Once contact TR1 is closed, the pump start switch may be opened and the trip Srelay remains energised by contact TR1.

Figure 1 shows other switching elements which form part of the normal control circuitry of the shuttle car.

The maintenance contact in the shuttle control circuitry is interlocked with the reset switch previously mentioned and when the reset switch is closed the maintenance contact is opened. Contact TR3 is closed when the trip relay TR is energised and as a consequence the pump coil for the pump which provides hydraulic power in the shuttle is energised.

Contact TR2 is closed when relay TR is energised and when TR2 is closed, power is supplied to the forward/reverse control switches in the shuttle car circuitry.

When a driver of the car selects forward motion (or reverse motion) using a foot operated switch, the appropriate traction contact closes energising the protection operation relay P0. When relay P0 is energised contact P01 in the shuttle car circuit closes to supply power to the shuttle car regulator which controls the speed of the shuttle car. Power is also supplied to a proximity detector relay and a sensor fail timer SF.

The internal contact of the proximity detector relay closes because the sensor relay has a normally closed contact. The proximity detector relay opens the internal contact when a metal tag moves past the sensor causing the sensor i: 20 contact to periodically open and then close in response to rotation of the cable reel on the shuttle car. This occurs and is indicative of either reeling in or paying out of cable. The metal tag is attached to a spooling shaft of the cable reel. This opening and closing of the internal contact in the proximity detector relay causes periodic energising and de-energising of the sensor relay SR. Sensor relay SR has associated contacts SR1 and SR2. When contact SR1 opens, the sensor fail timer SF is reset. When contact SR2 closes, the sensor timer ST is energised and timer ST starts timing.

When the metal tag does not move past the sensor coupled to the proximity detector relay because of reel jamming, the compartment carrying the reel being full of debris, cable jam or other reel malfunction the sensor relay SR is not reset and the sensor timer ST times out causing: a trip contact ST1 to close; the protection trip relay PTR to be energised; the alarm timer AMT to time for and an alarm to be sounded.

6 Contact PTR1 is caused to open when relay PTR is energised and this causes the trip relay TR to become de-energised opening contacts TR1, TR2 and TR3 which causes the electric/hydraulic pump to stop and the car brakes to be applied to stop the car and to prevent the car from running over and damaging the cable. The protection trip relay PTR is held in by contact PTR2 If the sensor contact fails remains open), the proximity detector relay internal contact stays open and the sensor relay SR isn't energised and contact SR1 remains closed. This causes the sensor fail timer SF to time out.

When sensor fail timer SF times out, contact SF2 closes and the protection trip relay PTR is energised which trips the shuttle car as explained above. When the sensor fail timer SF times out, contact SF2 closes and this keeps the sensor fail timer SF energised and contacts PTR3 and TR2 are opened.

Contact PTR3 when open prevents backfeeding of 11 0V power to the proximity detector relay. Contact TR2 when open ensures that an alarm does not sound when the driver of the car depresses a foot switch.

If a trip occurs and an alarm sounds, the driver must return the protection on/maintenance/reset switch to its off position to reset the protection system.

Following this, the switch may be closed again after the cause of the 20 trip has been rectified. The car may be restarted and traction selected. If the l switch is left in its open position, the shuttle car pump may be operated to allow the cable to be replaced but traction is locked out.

The pilot switch shown in Figure 1 detects when the enclosure 30 in Figure 3 is open and disables the shuttle car and renders the car inoperative.

Figure 2 shows detail of a siren and indication circuit. The 110V power is applied to the primary winding of a step down transformer and 24V is available at the secondary winding of the transformer this may be converted to DC. A siren provides the alarm signal previously mentioned whenever contact AMT1 is closed. When contact PTR4 is closed, the red indicator light is lit to indicate a protection trip/sensor fail condition. When the maintenance protection switch is shut, the green indicator light is lit to show that the protection system is on. Load resistors may be present in series with the indicator lights.

When contact P02 is closed, the green indicator light is lit to show that rotection is operative.

The system of the invention automatically checks for rotation of the reel and disables the drive for the shuttle car in the event that malfunction of the reel is detected. In this way, damage to the cable may be avoided.

Resistors R1, R2 and R3 are load resistors in series with the indicator lights.

Figure 3 shows the front 20 of a shuttle car. The car has an operator's cab 21 and a main control box 22 to a housing 24 which houses the system of the invention. The cable 25 which supplies power to the shuttle car is received between guide rollers 26, 27 and wound onto reel 28. Sensor 29 detects rotation of the reel 28 and the protection on maintenance switch 30 are shown coupled to the system in the housing 24. Siren 31 provides an audible output indicative of operation of the system.

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Claims (9)

1. A protection system for protecting a cable which supplies power to a shuttle car and which is wound round or unwound from a rotatable cable reel mounted on the car when the car moves, the system including a detecting means operable to detect whether or not the reel rotates at a rate which exceeds a predefined threshold value, and a control means communicating with the detecting means and operable to inhibit movement of the car and rotation of the reel in response to the detecting means detecting that the rate of rotation of the reel does not exceed the threshold value so that the cable is thereby prevented from becoming excessively slack or excessively taut.

2. The protection system of claim 1, wherein the detecting means includes a pulse generator operable to output a pulse during each rotation of the reel such that the rate at which the pulses are generated is proportional to the rate of rotation of the reel.

3. The protection system of claim 2, wherein the detecting means includes a first timer operable to time the interval between successive pulses, and the control means is operable to inhibit movement of the car and rotation of the reel if the time interval between the pulses exceeds a 20 predefined value.

4. The protection system of claim 2, wherein the detecting means includes a second timer operable to time the duration of the pulses, and the control means is operable to inhibit movement of the car and rotation of the reel if the duration of a pulse exceeds a predefined value.

5. The protection system of any one of the preceding claims, wherein the detecting means is operable to detect whether or not the reel rotates at a rate which exceeds the predefined threshold value after a driver initiates movement of the car.

6. The protection system of any one of the preceding claims, wherein 30 the control means is operable to inhibit movement of the car by causing a speed regulator of the car to be switched off. 9

7. The protection system of any one of the preceding claims, wherein the control means is operable to inhibit movement of the car by causing a braking mechanism of the car to stop the car.

8. The protection system of any one of the preceding claims, wherein the control means is operable to inhibit rotation of the reel by causing a pump associated with the reel to stop.

9. The protection system of any one of the preceding claims further including an alarm device operable to output an alarm signal in response to the control means inhibiting movement of the car and rotation of the reel. A protection system substantially as herein described with reference to the accompanying drawings. Dated this 18 of February 2003 PETER KARL ZETTL and PAUL RONALD ZETTL by their Patent Attorneys CULLEN CO o* 0