GB2190453A - Driving system for protection against overload of chain driven face working mining equipment - Google Patents

Abstract

A driving motor is followed by a planetary transmission including a disc clutch (1) which in the stationary position transmits the reaction torque of a component of the transmission, e.g. the outer central gear wheel to the transmission housing (3). The pressure in hydraulic or pneumatic cylinder (2) of the clutch (1) is controlled and/or the motor speed is varied according to signals from a speed measuring probe (6) indicating slip, the signal being processed in an electronic control circuit. The clutch (1) may also include a wear measuring probe. Instead of the plant carrier being driven and the ring gear being acted on by the clutch (1) as shown, the clutch may act on the carrier, whose speed is measured. The system may have several such drives controlled to regulate a scraper chain speed. <IMAGE>

Description

SPECIFICATION Adriving system for installations liable to overload, wffhsingle and multiple drives The Invention retesto a driving system for control of behavi:Esrin operation and for protection of installations liable to slhocks,oscillations andover- loads, particularly for cin-ain-driven face-working equipment in underground mining, in which each driving unit ofthe driving system possesses for speed reduction orfortorque increase a normally multiplestage distribution trnnsmissjon with concentricallylocated central gear wheels and distribution gear wheels located between them.

The disc clutch concentrically located within the transmission chain transmits solidly and without motion the reaction moment of each attached trans mission member-- preferably the outer central gear wheel ofthe faster-running transmission stage or its distribution gearwheels carrier directlyto the transmission housing.

According to the present invention, pressure-loading ofthe clutch piston takes place directly via the clutch cylinder which is rigidly connected to the transmission housing, whilst by suitable construction ofthe piston-cylinder combination the flame-resistant hydraulicfluid available underground attheface can be employed.

With the driving system according to the invention disc clutches can be used as protection against overload,evenwith highoutputsandhighoutput torques, as the clutch is so located within the transmission chain that medium torques are to be transmitted at medium rotational speeds. Also with the arrangement of the disc clutch according to the invention and by exploiting the constructional space available in spite of the compact construction of the distribution transmission, the specific loading ofthe clutch discs is kept low which has a favourable effect on the wearto be anticipated and also on the accuracy of response ofthe overload clutch when unacceptable overloads occur.

In known equipmentforthewinning andlorcon- veyance of coal with a drive assembly and a slipping clutch, an overload clutch is located in the path of the torque between the main stage and the preceding stage to connect the torque-transmitting shafts together.

The overload clutch, constructed as a slipping clutch, consists of two clutch halves rotating at the speed ofthe shafts to be connected together, which transmit the torque byfrictin:'via the discs from one clutch halfto the other.

The pressure medimtoto load the piston-cylinder device is introdexedviaian! intermediate so-called rotary transmission.

To ddexltstiptlle rotational speeds ofthe clutch halves are deteanined by at least two inductive proximityswitchesanci passed into a monitoring equipment.

In contrast with th is, in the driving system according to the invention considerable advantages in respect of the high operating reiiability required of such driving systems result from the possibility of direct pressure loading on the clutch through the outerwall ofthe clutch cylinder. Atthe same time the axial movements ofthe piston relatively to the cylinder are small so that practically no wear of the seal and consequent loss by leakage are to be expected over the whole working life. If the disc clutch, in addition to its function as overload protector, is used to control the starting-up and reversing processes of e.g. coal plough drives, then with the very frequent actuations to be expected two seals can be provided, one behind the other, with intermediate feedback holes for the direct extraction of leaked fluid.

Also the so-called "unloaded running-up" of motors followed byswitching-on or engagement of the clutch during the running-up process, and if required a successive engagement of the clutches when there is a multi-motordrive, requires particularly accurate determination ofthe variation of temperature and the condition ofwear of the clutch discs.

With the driving system according to the invention permanentlywired-in measuring probes can be inserted directly into the outer discs ofthe clutch.

Similarly the condition of wear ofthe clutch can be accurately determined by means of permanently wired-in proximity switches providing measured values ofthe changed piston position when the clutch is engaged. The measured values arethen submitted for evaluation to the measuring appliance in the electronic control.

Also in accordance with the present invention, the driving system is equipped with a slip monitor ofthe disc clutch, wherebythe slip is detected by direct mechanical contact or, preferably, determined by inductive approach switches to provide measured values and conductthem to the electronic measurement and control appliance for evaluation, i.e. recognition of slip. These functions can be ensured merely by a single measurement unit, which can be installed as part ofthe slip monitoring either in the immediate vicinity ofthe rotating part ofthe clutch or in the neighbourhood ofthe transmission component, e.g.

the outer central gearwheel, that is attached to the rotating part.

The electronic measurement and control appliance preferably evaluates the test data according to period of slip, extent of slip and also the series of occurrences of slip at intervals of time, compares these with the desired values, and when these associated desired values are exceeded operates the electro-hydraulic or electro-pneumatic control of the dise clutch and initiates the switching-on ofthe motor.

With multiple drives the driving system according to the invention can be adapted to ensure simultaneous actuation of all the disc clutches and simultaneous actuation of allthe motors, initiated by the electronic measurement and control appliance of a single drive.

The clutch characteriscs and thereby the behaviour ofthe driving system as a whole can be influenced to a considerable extent by the clutch pressure selected, the course of pressure-reduction in the clutch and the residual clutch pressure selected. The values can be pre-set "by hand" via the control appliance, orthe control appliance can be set to produce the desired system behaviour by means of so-called "Programme Modules" which are e.g. plug-in modules that either determine the behaviour of the system by means of their external shape or act electronically upon the control appliance.

A programmable alteration of clutch characteristics with the time may also be provided and brought into operation e.g. to obtain equalization of load on the individual drives of chain-driven face-working equipment driven by multiple drives. According to this programme the clutch torque of a single drive is reduced for a short time to such an extent that the clutch begins to slip, and this is repeated for each of the drives in succession.

In the following description an embodiment ofthe invention is explained, byway of example only, and with reference to the accompanying drawings, showing: Figure 1-The schematic representation of a distribution transmission with a multiple disc clutch 1 attached to the outer central gearwheel of the fast-running transmission stage, its clutch cylinder2 being rigidly connected to the transmission housing 3 via the carrier of the outer clutch discs 7. Pressure loading ofthe clutch piston is effected directly via the clutch cylinder 2. The clutch cylinder 2 is pressurized in the engaged position of the clutch. In the case illustrated release ofthe clutch takes place mechanically by retracting springs 8, after decrease of the clutch pressure.Withdrawal of the piston could also be effected hydraulically or pneumatically with appropriate constructional design. The inductive pro ximity switch 6, as part ofthe slip monitor 5, serves for contactless slip detection, and can as shown in Figure 1 be effected directly on the rotating part ofthe clutch 4 or on the transmission components that are rigidly attached to that part ofthe clutch 4.

Figure la-The schematic representation of a distribution transmission with a disc clutch 1 attached to the carrier of the distribution gearwheels ofthe fast-funning transmission stage. A possible constructional variation ofthe multiple disc clutch is also shown. In this case the clutch piston, contrary to the clutch construction of Figure 1, is engaged bythe resilience ofthe compression springs 9. Control and release ofthe clutch takes place by direct pressure loading of clutch cylinder2. The slip monitor 5with proximity switch 6 is here by way of example located in the area of the distributor gear wheels carrier, a transmission element attached to the rotatable part of the clutch 4.

Figure 2 shows the basic construction of a driving unit of the drive system consisting ofthe distributor transmission with integrated multiple discclutch as an actuating clutch, overload clutch, or equalization clutch. As is shown in Figure 2, a chain wheel forthe direct drive of chain-actuated machines, e.g. coal ploughs, can be located on the output side ofthe distribution transmission, which in the representation selected is connected to the driving motor via a motor distance-piece. The measurement and control appliance loins also shown.Whilst the hydraulic or pneumatic control 12 ofthe measurement and control appliance 10 is advisably located in the immediate vicinity of the driving unit or directly on the distribution transmission, the electronic control 11 of the measurement and control appliance can be located at a greater distance, e.g. in the control pulpit of the machine. With multiple drives the electronic controls ofthe individual drive units can be brought together in the control pulpit or even be combined in a single electronic control.

Figure 3 shows the "measurement and control appliance" assembly 10 of the driving system, the arrangements of which can be effected as described under Figure 2. The electronic signals of slip monitor 5 of Figure 1 or Figure 1 a are conducted as measured data signals to the electronic control for recognition and evaluation of slip, which according to the programmed desired values in the construction of the measurement and control appliance according to a preferred feature ofthe invention can for example lead to the following reactions ofthe electronic control: The slip displacement of the clutch exceeds the pre-programmed vaule, e.g. ifthe coal plough stalls; this results in a reaction ofthe electronic control whereby operation ofthe clutch by means ofthe hydraulic or pneumatic control and that of the driving motor can take place simultaneousiy or in succession.

If there is a succession of occurrences of slip at intervals oftime, e.g. with impact loading of the machine, a single slip of which has not led to any reaction by the electronic control, or if there is inadmissible slow slip ofthe clutch a reaction of the electronic control will take place when the total amount of slip exceeds that of the desired value of an electronic shift register in a prescribed time-interval.

Further measured values, e.g. those resulting from temperature and wear observation of the clutch or temperature observation of the distribution transmits sion, and additional measured values that are of importancetothe running ofthe machineasawhole can be appropriate design of the measurement and control appliance be processed and, in comparison with desired values, be converted into reactions of the control.

Figure 4 shows a multiple drive. Afour-fold drive of a scraper-chain conveyor is represented, with direct installation ofthe hydraulic or pneumatic control on each distribution transmission. The electronic con trolsarecombined in a joint control.

Claims (6)

1. A driving system for control of behaviour in operation and forthe protection of installations liable to overloads, such as chain-driven face-working equipment in underground mining, with single or multiple drives, in which each drive consists of a driving motor, followed by a distribution transmission with concentricaily-located central gear wheels and distribution gear wheels located between them, and a hydraulically or pneumatically operated disc clutch, concentrically located within the transmission chain, which transmits to the transmission housing the supporttorque ofthe outer central gearwheel or the distribution gear wheels carrier and a measurement and control appliance for electro-hydraulic or electropneumatic control ofthe clutch and control ofthe driving motor, and in which the clutch piston is directly loaded with pressure via the clutch cylinder which is rigidly connected to the transmission housing and the rotatable part of the clutch is provided with a slip monitor whereby the slip is detected either by directmechanicalcontactorwithoutcontactbyone or more inductive approach switches the electrical sig nals which are conducted to the measurement and control applianceforslip recognition.

2. Adriving system according to Claim 1 ,wherein the period slip, the extent of slip, and the series of occurrences of slip at intervals oftime are electronically evaluated in the control appliance, compared with the desired values, and whentheassociated desired values are exceeded the control appliance operates the motor via the electronic control and further operates the clutch via the electro-hydraulic or electropneumatic control.

3. A driving system according to Claim 1 orClaim 2, wherein when there are multiple drives actuation of the clutches and motors of all the drives occurs simultaneously, initiated by the control appliance of a single drive.

4. A driving system according to any one of Claims 1 to 3, wherein the clutch characteristics in respect of responsetorque and torque curve is adjustable by the clutch pressure selected, the course of pressure reduction and the residual clutch pressure selected, via the electro-hydraulic or electro-pneumatic control ofthecontrol appliance.

5. A driving system according t6 Claim 1, wherein the clutch characteristic can be varied in accordance with time by control appliance, and particularly that when there are multiple drives the clutch torque of a single drive is so controlled by adjusting the clutch pressure that by means of a deliberate amount of slip that is induced in succession by the control appliances of the individual drives continuous balancing of loads on the individual drives of a multiple drive is achieved.

6. A driving system for control of behaviour in operation and forthe protection of installations liable to overloads substantially as hereinbefore described with reference to the accompanying drawings.