US3771830A

US3771830A - Mining machine sensing signal transmission connection

Info

Publication number: US3771830A
Application number: US00205694A
Authority: US
Inventors: D Hartley; N Plumpton; D Alford
Original assignee: Coal Industry Patents Ltd
Current assignee: Coal Industry Patents Ltd
Priority date: 1971-12-07
Filing date: 1971-12-07
Publication date: 1973-11-13
Anticipated expiration: 1990-11-13

Abstract

A mineral mining machine having a rotary cutter and a probe on the cutter head which senses the cutting horizon of the cutter head relative to boundaries of the mineral seam and which derives an electric signal which is fed to control means on the body of the machine for controlling the machine''s steering mechanism. The signal is conveyed from the rotating cutter to the non-rotating body via two spaced annular plates arranged as a capacitor.

Description

United States Patent 11-91 Hartley et al. v

1451 Nov. 13, 1973 MINING MACHINE SENSING SIGNAL TRANSMISSION CONNECTION Inventors: Dennis Hartley; Derek Alford;

Norman Albert Plumpton, all of Burton-on-Trent, England Assignee: Coal Industry (Patents) Limited,

London, England Filed: Dec. 7, 1971 Appl. No.: 205,694

us. Cl. 299/1, 339/5 R 1m. 01. E21c 35/24, HQ 1r 39/56 Field of Search 299/1; 339/5 R, 5 P,

References Cited UNITED STATES PATENTS Addison 299/1 Wachsman 339/5 P Snodgrass et al. 339/8 R Primary Examiner-Ernest R. Purser Attorney-Richard K. Stevens et a] [57] ABSTRACT .A mineral mining machine having a rotary cutter and a probe on the cutterhead which senses the cutting horizon of the cutter head relative to boundaries of the mineral seam and which derives an electric signal which is fed to control means on the body of the machine for controlling the machines steering mechanism. The signal is conveyed from the rotating cutter to the nonerotating body via two spaced annular plates arranged as a capacitor.

8 Claims, 2 Drawing Figures MINING MACHINE SENSING SIGNAL TRANSMISSION CONNECTION This invention relates to mineral mining machines and in particular to mining machines of the kind comprising rotary cutters from which it is necessary to conduct electric signals, for example a machine having means on the cutter which are sensitive to the mineral being cut by the cutter and which produce a signal indicative of the mineral being cut, the signal being conducted to the steering mechanism of the machine.

With known mining machines of this kind slip-rings were used to conduct the signal from the rotary cutter to the body of the machine. Unfortunately, such a technique was found to be unreliable, and liable to be affected by mineral particles which penetrated into the slip-ring chamber. Such a technique also suffered from the effect of electrical noise interference which tended to mask out any change in the signal due to a change in the mineral being cut by the cutter.

An object of the present invention is to provide a mining machine comprising improved means for conducting an electrical signal from the rotary cutter to the body of the machine.

According to the present invention a mineral mining machine comprises a body, a rotary drive shaft extending from the body, a rotary cutter mounted on the shaft, means sensitive to a characteristic feature existing adjacent to the cutter and adapted to produce an electric signal indicative of the feature, and first and second electrically conductive annular elements coaxial with the drive shaft and Spaced from, but adjacent to, each other, the first element being in electrical contact with the means and mounted for rotation with, but electrically insulated from, the cutter, the second element being mounted on, but electrically insulated from, the machine body and being in electrical contact with receiver-means adapted to receive electric signals.

Advantageously, the said first and second elements are located within a packed annular chamber the sides of which are formed partly by a rotary housing member secured to the cutter and partly by a stationary housing member-secured to the machine body.

Preferably the annular chamber is packed with an epoxy resin. Alternatively, the annular chamber may be packed with grease.

Preferably, the radially outer portions of the two housing members form a labyrinth.

An annular resiliently urged seal may be located so as to act between the two housing members.

Preferably, the said means are sensitive to the cutting horizon of the cutter and the receiver means are control means adapted to control the steering mechanism of the machine.

By way of example only, one embodiment of the invention will now be described with reference to the accompanying drawings in which i FIG. 1 is a diagrammatic sectional view along a drive shaft of a mining machine constructed in accordance with the present invention;

FIG. 2 is an incomplete diagrammatic sectional view along line II--Il of FIG. 1.

Referring to the drawings which show a part of a mining machine adjacent to the cutting end of the machine and in particular the part where the rotary cutting unit 2 is attached to the non-rotary body 4. The cutting unit 2 comprises a rotary drive shaft 6 and a cutter drum 8 drivably mounted onto the shaft 6.

The cutter drum 8 is provided with means 9 sensitive to the cutting horizon of the cutter drum 8, which comprise a flexibly mounted cutter tool 11 the vibrational movement of which with respect to its mounting depends upon the hardness of mineral momentarily being cut by the rotating tool, and a device which is sensitive to such movement and which produce an electrical signal having a frequency indicative of the movement. The signal is fed from the device along a cable (not shown) housed within passages 10 (only one of which is shown) provided on the drum 8, and a passage 12 provided in a rotary housing member 14 secured to the drum 8by bolts 15. The cable is connected to a terminal 16 rigidly attached to an annular plate18 which is secured to a ring 20 of electrically insulating material bolted by recessed bolts 22 to the housing member 14, the plate 18 being arranged co-axial with the drive shaft 6.

A second annular plate 24 is mounted adjacent to, but spaced from, the plate 18 and is secured to a ring 26 of electrically insulating material bolted by recessed bolts 28 to a stationary housing member 30 which is bolted by bolts 32 to the machine body 4. A cable (-not shown) is connected to a terminal 34 rigidly attached to the plate 24 and extends along a passage 36 in the housing member 30 and the casing of the machine body 4 to receiver means 37 adapted to receive the electric signals and to feed the signals to control means (not shown) which control the steering mechanism of the machine.

The rotary and

stationary housing members

14, 30 form an annular chamber 38 having two

portions

39, 41 within which are housed the

plates

18 and 24, respectively, and which are packed with a suitable nonelectrically conductive material, as for example an epoxy resin or grease which tends to prevent moisture and particles of mineral entering the chamber 38.

In the case of the chamber 38 being packed with epoxy resin, the

housing members

14, 30 are laid on the ground with their

respective chamber portions

39, 41 uppermost. Next the

plates

18, 24 arellocated in position within the chamber portions '39, 41, respectively, and the cables connected to the terminals, 16, 34 and passed along the

passages

12, 36 which are then plugged by resilient stoppers. Molten epoxy resin is then poured into the

chamber portions

39, 41 until the portions are full with the

plates

18, 24 completely covered by the resin which is then allowed to set. When the epoxy resin is set the

housing members

14, 30 are assembled and connected to the cutter drum 8 and the body of the machine, respectively, with the two exposed faces of the epoxy resin adjacent to each other. A thin layer of grease may be provided between the two faces of the epoxy resin. In addition before the epoxy resin is poured into the

chamber portions

39, 41 the inside walls of the portions may be sprayed with a nonelectrically conductive varnish which ensures that during any subsequent operation of the machine, if any water should enter the chamber 38 it cannot cause an electrical short circuit.

1 The radially outer portions of the two

housing members

14, 30 form a labyrinth which assists in preventing particles of mineral entering the chamber 38.

Two resiliently loaded

annular seals

40, 42 are located in grooves formed in the rotary housing member l4, and arranged to act between the two

housing members

14, 30. Each

seal

40, 42 comprises a nylon pad 44 which is urged towards the stationary housing member 30 by a spring 46, the force of which can be adjusted by screw adjustments 48.

In alternative arrangements of the invention one or both of the

seals

40, 42 are dispensed with.

Grease nipples 50 are provided for feeding grease into the labyrinth.

In operation the electrical signal which has a frequency proportional to the hardness of the mineral being cut by the cutting drum 8 is fed from the previously mentioned means 9 to the annular plate 18 via the terminal 16. The two

annular plates

18, 24 form a capacitor coupling and an electrical signal having a lower amplitude, but the same frequency as the signal fed to the plate 18 is conducted from the plate 24 via the terminal 34 to the receiver means 37 an in turn to the control means.

Upon the cutter drum cutting a mineral of differing hardness, the frequency of the signal fed to the plate 18 and consequently of that conducted from the plate 24, is changed by a proportional amount. Thus the control means is informed of the change in cutting horizon of the cutter drum 8 and the steering mechanism is actuated to suitably steer the machine and adjust the cuttin horizon.

Typical spacing of the

plates

18, 24 is betwee 1/ The invention provides a means of conducting electrical signals from the rotating cutter unit 2 to the body 4 of the machine which is reliable, robust and relatively free from electrical noise. Thus any change in signal due to change in the cutting horizon of the cutter and hardness of mineral being cut can be easily recorded.

The invention can be also used with other sensitive means mounted on the rotary cutter unit which produce an electric signal, for example with nucleonic probes mounted on the unit and arranged to detect the boundary of a mineral adjacent to the cutter unit, or a probe sensitive to the gaseous atmosphere around the cutter unit.

We claim:

1. A mineral mining machine comprising a body, a rotary drive shaft extending from the body, a rotary cutter mounted on the shaft, means sensitive to a characteristic feature existing adjacent to the cutter and adapted to produce an electric signal indicative of the feature, receiver means mounted on the body and adapted to receive electric signals, and first and second electrically conductive annular elements co-axial with the drive shaft and spaced from, but adjacent to, each other, the first element being in electrical contact eith the means and mounted for rotation with, but electrically insulated from, the cutter, the second element being mounted on, but electrically insulated from, the machine body being in electrical contact with the receiver means.

2. A machine as claimed in claim 1, comprising two housing members which form a housing within which the first and second elements are located, one of the housing members being secured to the cutter and the other housing member being secured to the machine body.

3. A machine as claimed in claim 2, in which the housing is packed with an epoxy resin.

4. A machine as claimed in claim2, in with the housing is packed with grease.

5. A mineral mining machine comprising a body, a rotary drive shaft extending from the body, a rotary cutter mounted on the shaft, means sensitive to the cutting horizon of the cutter relative to the mineral seam and adapted to produce an electric signal indicative of the cutting horizon, receiver means mounted on the body and adapted to receive the electric signals, first and second electrically conductive annular elements co-axial with the drive shaft and spaced from, but adjacent to, each other, the first element being in electrical contact with the means and mounted for rotation with, but electrically insulated from, the cutter, the second element being mounted on, but electrically insulated from, the mahcine body and being in electrical contact with the receiver means, and two housing members which form a housing within which the first and second elements are located, one of the housing members being secured to the cutter and the other housing member being secured to the machine body.

6. A machine as claimed in claim 5, in which the housing is packed with a non-electrically conductive material.

7. A machine as claimed in claim 5, in which the radially outer portions of the two housing members form a labyrinth.

8. A machine as claimed in claim 6, in which at least one resiliently urged seal is located so as to act between the two housing members.

Claims

4. A machine as claimed in claim 2, in with the housing is packed with grease.