CA1185321A - Hydraulic motor driven electric generating unit - Google Patents
Hydraulic motor driven electric generating unitInfo
- Publication number
- CA1185321A CA1185321A CA000398274A CA398274A CA1185321A CA 1185321 A CA1185321 A CA 1185321A CA 000398274 A CA000398274 A CA 000398274A CA 398274 A CA398274 A CA 398274A CA 1185321 A CA1185321 A CA 1185321A
- Authority
- CA
- Canada
- Prior art keywords
- power unit
- machinery
- unit according
- generator
- housing
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K7/00—Arrangements for handling mechanical energy structurally associated with dynamo-electric machines, e.g. structural association with mechanical driving motors or auxiliary dynamo-electric machines
- H02K7/18—Structural association of electric generators with mechanical driving motors, e.g. with turbines
- H02K7/1807—Rotary generators
- H02K7/1823—Rotary generators structurally associated with turbines or similar engines
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F21—LIGHTING
- F21S—NON-PORTABLE LIGHTING DEVICES; SYSTEMS THEREOF; VEHICLE LIGHTING DEVICES SPECIALLY ADAPTED FOR VEHICLE EXTERIORS
- F21S9/00—Lighting devices with a built-in power supply; Systems employing lighting devices with a built-in power supply
- F21S9/04—Lighting devices with a built-in power supply; Systems employing lighting devices with a built-in power supply the power supply being a generator
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F21—LIGHTING
- F21V—FUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMS THEREOF; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHER ARTICLES, NOT OTHERWISE PROVIDED FOR
- F21V25/00—Safety devices structurally associated with lighting devices
- F21V25/12—Flameproof or explosion-proof arrangements
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K5/00—Casings; Enclosures; Supports
- H02K5/04—Casings or enclosures characterised by the shape, form or construction thereof
- H02K5/12—Casings or enclosures characterised by the shape, form or construction thereof specially adapted for operating in liquid or gas
- H02K5/136—Casings or enclosures characterised by the shape, form or construction thereof specially adapted for operating in liquid or gas explosion-proof
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F21—LIGHTING
- F21Y—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES F21K, F21L, F21S and F21V, RELATING TO THE FORM OR THE KIND OF THE LIGHT SOURCES OR OF THE COLOUR OF THE LIGHT EMITTED
- F21Y2103/00—Elongate light sources, e.g. fluorescent tubes
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Arrangement Of Elements, Cooling, Sealing, Or The Like Of Lighting Devices (AREA)
- Connection Of Motors, Electrical Generators, Mechanical Devices, And The Like (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
An electrical power unit is provided particularly for use in underground mining insulations, where fire risks are especially serious. The unit has an hydraulic motor adapted to be connected to a hydraulic circuit having a flow and return line, and an electric generator arranged to be driven by the motor, the motor and the generator being located within a flameproof housing and being arranged to provide a d.c. output of up to 24 volts and including a current limiter circuit for limiting the current supplied by the generator to 0.7A or less. Fluorescent light units are connected to the current limiter circuit by cables.
The hydraulic motor may with advantage be connected directly to the hydraulic circuit of a mining machine such as, for example, a powered roof support. The power unit and light units may be housed integrally within a powered roof sup-port, to provide light at a coal face, in a safe and re-liable manner.
An electrical power unit is provided particularly for use in underground mining insulations, where fire risks are especially serious. The unit has an hydraulic motor adapted to be connected to a hydraulic circuit having a flow and return line, and an electric generator arranged to be driven by the motor, the motor and the generator being located within a flameproof housing and being arranged to provide a d.c. output of up to 24 volts and including a current limiter circuit for limiting the current supplied by the generator to 0.7A or less. Fluorescent light units are connected to the current limiter circuit by cables.
The hydraulic motor may with advantage be connected directly to the hydraulic circuit of a mining machine such as, for example, a powered roof support. The power unit and light units may be housed integrally within a powered roof sup-port, to provide light at a coal face, in a safe and re-liable manner.
Description
3~
~his invention relates to electrical power units, and i8 particularly although not exclusively concerned with electrical power units tha-t are suitable for use in hazardous enviro~ments, such as9 ~r example, in underground mining.
Safety in mines has improved considerably over recent yearsO However~ developments in mining technolog~ led to the use of extremely large and powerful machiner~ at the coal face, and in the v~init~ thereo~.
Due to the nature of mining, ~uch machinery is regularly mo~ed~ Consequentlyj face workers in a modern mine can still face great hazards from the complex of machiner~, ancillary equipment~ cables~ etc.in and around the work areaO
Such hazards are aggravated by the fact thatt despite advances in technology7 it has not ~et been found possible t id lefftlC~ent 1 li hti f 1 f ~ f the potential dangers from moving machinery, regulations rescribe th t electric cab~Veesrl s~eclftl~ volta~eds d ithi specified distance of coal ~aces~ This is because of the high risk o~ rupturing such cables, with the consequent risk of electric shock9 and gas explosion from electric arcs~
~hUg7 face workers have to work in these extremely hazardous areas with virtually no lighting. The risks of accident are therefore gravely accentuated.
~ighting s~s~ems that have bee~ adopted in minin~
environments do tend to have a number of inherent problemsO
~or example, previously proposed wholly electrical systems 3~
have the disadvantage that a high voltage source is required near the point of use, and bulky transformers and converter units are required at frequent intervals along the power distribution system. It is possible only to run five single lamps each of seven watts output from one converter, and it is possible only to run a seven metre length of cable from each converter to each single lamp unit (thus limiting the positional capability of each lamp, with respect to the converter source~. Thus, there are numerous cables required, which can be severed and cause shock or sparking, the cables/liveYcugrrent at 110/125 volts. Such wholly electrical systems require a high consumption of electrical power, and -for transmission of power over 200 metres or more, there is inefficient striking of the lamps, due to power drop.
~15 Another system that has been proposed uses lamp units that are driven by pneumatic power, which power is converted to electrically energy by a generator within the lamp unit.
However9 such a system has not been adopted for a number of reasons. For example, the generators tend to be very bulky, causing the individual lamp units to be bulky, and only single lamp units are available, of relatively poor lighting capability. There is present a high noise level upon starting and during operation of such units, and a large amount of heat is gènerated from each unit in continuous use. There tends to be a rapid power drop of pneumatic power with distance, which severely restricts ~he distances over which light units can be used. Overall, such lamp units tend to be unreliable.
We have also become aware of lamp ~mits similar to the above, but in respect of which it is said that they may be driven by hydraulic power. However, the only design of such lamp units that we have seen can not possibly afford safe running in present day mining conditions, ;~. IL~53~
and has attendant disadvan-tages similar to -the pneumatically driven lamp units mentioned above.
Preferred embodiments of the present inven-tion aim to overcome these disadvantages, by providing reliable ligh-ting units that may be used safely in hazardous conditions.
However, the invention generally is of wider applica-tion.
According to the present invention, there is provided an electrical power unit which comprises an hydraulic mo-tor adap--ted to be connected to a hydraulic circuit having a flow and return line, and an electric generator arranged -to be driven by the motor, the motor and the generator being located wi-thin a flameproof housing and being arranged to provide a d.c. out-put of up to 24 volts and including limiting means, for limit-ing the curren-t supplied by the genera-tor to 0.7~ or less.
It may be appreciated that power units in accordance with the invention can be designed to be safe for use in hazardous areas - e.g. where there is a risk of cable severance or explosive gas. Then, severance of an hydraulic pipe can be of relatively minor consequence. Preferably, means is provided for blocking flow in an hydraulic pipe supplying a power unit in accordance with the invention, in the event of a loss in pressure greater than a predetermined value, as may occur, for example, in a pipe fracture.
Numerous advantages and optional features of the inven-tion will be apparen-t from the following descrip-tion of pre~
ferred embodiments -thereof.
In this specification, the expression "low voltage" is defined as a voltage which is low relative to -that employed previously in mines - i.e. low relative to a vol-tage of 110/125 volts. We believe tha-t the invention is particularly advan-tageous where the power unit provides an output of up to 6 volts, 12 volts, or at the most 24 vol-ts d.c., although the invention is not necessarily limited to these par-ticular figures.
For a better understanding of the invention, and to show how the same may be carried in-to effect, reference will now be made, by way of example, to the accompanying diagrammatic drawings, in which:
. ~
~S3;~
Figure 1 is anhydraulic flow diagram of a lighting system embodying the invention;
Figure ~. is an electrical circuit diagram of a lamp unit embodying the invention;
Figure 3 shows one example of a lamp unit, in cross~section;
Figure 4 shows an.other example of a lamp unit, in cross-section;
Figure 5 shows, in plan view, a coal face provided with a lighting system embodying the invention;
t5 - Figure 6 shows the coal face in front elevation;
Figures 7, 8 and 9 show lamp units fit~ed to respective roof supports or shields as seen respectively on the lines C-C,.B-B and A-A of Figure 5;
Figure 10 is a perspective view of one example of a lamp unit as used in Figures 5.to 9;
.
Figure 11 is a perspective view of another example of a lamp unit; an~
Figure 12 is a circuit diagram of a current limiting circuit of the lamp unit of Figure 11.
In the figures, like reference numerals denote like or corresponding parts.
~ ~ ~ 5 3~
The lighting system illustrated in Figure 1 is suitable for use in underground mining, where it can be used with relative safety. The system comprises a reservoir 1 of hydraulic fluid, and a pump 2 which is arranged to be driven by a motor 3 The motor 3 can be any suitable prime mover, such as/electric or diesel motor, and may be of 40 horse power or less. The pump 2 is arranged to pump hydraulic fluid around the system at a rate of 27.5 gallons per minute, at a pressure of about 1600 P.S.I. A relief valve assembly 6 is provided between flow and return lines 4 and 5, to relieve excess pressure in the system. The /
-53~
parts 1 to 6 thus described afford an hydraulic fluid supply system~ having flow and return ports 7 and 8~
In use, an hydraulic distribution system having flow and rt~urn pipe~ 9 and 10 i5 connected to the ports 7 and 8 of/suppl~ system. At desired intervals 7 there are provided pairs of tees 119 12, etc. in the pipes 9 and 10.
Each tee is provided with a respective non-return valve 139 to pro~ide a connection to the respective flow or return pipe 9 or 10 via the respective teeO A respective lamp unit 14, 15 etCu i8 connected between each pair of tees 11~ 12 etcO, via the one-way valves 13. Each lamp unit 14, 15 etcO compr~s an h~draulic motor which is arranged to drive an electriC generator9 which in turn supplies a respective light.
Figure 2 is an electrical circuit diagram showing one example of a lamp unit 140 '~he lamp unit 14 comprises an hydraulic motor 16, through which h~draulic fluid passes via flow and return lines 17 and 18. The output shaft of th~e hydraulic motor 16 is connected to an electric generator 19 by means ~ a flexible coupling 20. Th0 output of generator 19 is regulated by a regulator 21, and is fed to three ballast units 229 in parallelO Each ballast unit 22 supplies a respective fluorescent tube 230 ~ he hydraulic motor may be of approximately ~ horse power rating~ and have a drive speed in the range 800 to 2000 r,p.mO ~he generator 19 may be a 12 volt - 60 watt DC dynamoO
3o Ballast units 22 and fluorescent tub~ 23 may be of about 8 watts rating.
Figures 3 and 4 show alternative example5 of const~1ction of a lamp unit 14. In ~igure 3, the flow and return hoses 17 and 18 make connection at one end of a housing 24~ to the _ 7 _ hydraulic motor 16. ~he hydraulic motor 16, coupling 20 and electric generator 19 are all mounted in one section of -the housing 24~ and the regulator 21, ballast 22, and tubes 23 are mounted within another section of the housing 24. ~he housing 24 is sealed by a cover 25, in a flameproof and fluid~ight manner.
In Figure 4, a fluorescent tube 23 extends perpendicularly to the axis of the generator 19~ rath~r than parallel to it. In ~igure 4~ there can be seen a glass 26, which seals the housing 24. In both Figures 3 and 4, the electrical circuitr~ ma~ be sunk within epoxy resin ~el~
to protect components from shock load or external vibration transmitted from local machinery, etcO
In the illustrated system, the hydraulic fluid may comprise exclusively oil, or of an emulsion of 60/40 or 95/5 mixture oi.l/water, for example. Alternatively9 the h~draulic fluid may be water alone. In the illustrated arrangement, the hydraulic supply system may be sufficient to light 100 lamp units spaced over a distance of 200 metres.
Within each lamp unit such as 14, it is possible to light either 10 six inch fluorescent tubes, each 4 watt; 5 twelve inch flu~escent tubes9 each 8 watt; 4 twenty-one inch flu~rescent tubes, each 12 watt, or 2 tungsten spotlight units, each 25 wattsO ~ach lamp unit has no external electric circuitry~ and operates on ver~ low voltage - for example, 18 volts maximum across each fluorescent tube.
~ach lamp unit such as 14 may be a hand held inspection lamp, or may be designed for securement to a surface~ ~amp units such as 14 may be fitted into any existing type of equipment which ~s a suitable hydraulic fluid system incorporated therein.
-- 8 ~
In the ~y,stem shown in ~lgure ~ each lamp unit 14~ etc~ may be removed safely from the system without switching off the other lamps in the system. ~lso, each lamp unit ~4 is so designed as to allow any one light within that unit to fail whilst the others within the unit remain lit.
Figures 5 to 9 show how a lighting system as illustrated in ~igure 1 may be installed at a coal face~
A pluralit~ of roof supports and/or roof shields 27 is arranged across a coal face 28, and at face ends 290 Various mining machinery is installed at the coal face, although this machiner~ is not shown in detailO Coal mined from the face 28 is carried away on a stage loader co~ve~or 30q at the main gate 31 to the face 280 An hydraulic pressure-fluid supply system, such as that shown in ~igure 1 (parts 1 to 6) is mounted on the stage loaderT
A lamp unit 3Z (equivalent to the lamp units 149 15, etc) is mounted o~ each of the roof supports 27, and is connected to flow and return pipes supplied by the hydraulic pressure-fluid suppl~ s~stem 330 ~ach lamp unit 32 is arranged to light both the gallery ~ and the coal face ~8~ A face conveyor 40 conveys coal from the face 28 to the stage loader conve~or Figure 10 illustrates one example of la~p units 32 ~ach lamp unit 32 has a totally sealed flameproof housing 35 At a centre part of the housing 359 there are provided flow, 3o and return ports 36 and 37~ which lead to an hydraulic motor and electrical generator within the housing 350 ~t one side 38 of the housing 35~ there are mounted two fluorescent tubes which are arranged to project light downwardly9 as shown by the arrow ~0 At an opposite side 39 of the housing 35~ there are mounted three fluorescent tubes~ which are respectively _ 9 _ arranged to project light horizontallyg obliquely downwardly9 and vertically downwardly, as shown by the arrows Bp C and Do ~he housing 35 is arranged to be secured to the canopy of a roof support 27, as shown in Figures 5 to 9~ such that the two tubes at the side 38 of the housing 35 project light downwardly into the gallery 34, whilst the three tubes at the opposite side 39 project light into the coal face 280 It may be appreciated that the illustrated arrangements pr~vide a lighting system which is inherently safe for use in hazardous areas, such as are found in mines9 chemical storage vessels, and areas where chemicals or gaseous elements existp Experiments have shown that lamp units as illustrated can have excellent light output, whilst being of relatively modest power consumption, and light in weight~ At any particular installation, an hydraulic fluid distrubution system may be supplied with tees such as 11 and 12 at any desired intervals, such that inspection lamp units or semi-permanent lamp units may be connected thereto as desired. Preferably~ the hydraulic pressure-fluid s`upply system is provided with means for blocking flow in the flow and return pipes9 in -the event of a loss in pressure greater than a predetermined value~ as may occur~
for`example, in a pipe fracture~ ~hus, in the event of a fracture of an hydraulic pipe in the illustrated system~
potentially the most serious event would simply be loss of light~ The arrangement may be such thatS in the event of such light loss9 associated m~hiner~ is automatically turned of~.
3o As noted above, lamp units in accordance with the invention may be provided integrally on apparatus which has its own suitable supply of hydraulic pressure-fluid~ such as, for example, a powered roof support.
53~:~
Although the illustrated arrangements are concerned with lighting units, it ma~ be appreciated that the in-vention may be exten~ed to provide portable power units for any requirementO ~or example~ each housing 24 may contain any desired electricall~ driven device or apparatus~ Alternatively~
each housing 24 may be provided with electric terminals for connec-tion to electrically driven apparatusO Such units may advantageousl~ proyide an electrical suppl~ at low vo~ge, in ~ safe and convenient mannerO
As an alternative to the h~draulic pressuxe fluid suppl~ system shown in Figure 1~ there may be provided two 20 horse power motors, each driving a respective pump - and i~dependent hydraulic fluid distribution system? the two pumps being supplied ~rom the common reservoir 1.
The two hydraulic fluid distribution s~stems are preferabl~
interlaced in a lighting s~stemO ~hen~ in the event of failure of one of the distribution ~ystems, only a portion (e~gO a half) of the lights in the lighting system may be extinguished. ~his is p~rticularly advantageous from the aspect of safety.
The alternative lamp unit 40 which is shown in Figure 11 comprises an hydraulic motor 41 and an electric `25 generator 42, each of which is disposed within its own flameproof housing, which housings are bolted one to the other. Flow and return hoses 43 and 44 are connected to the hydraulic motor 410 A current regulator 45 is disposed in its own flameproof housing, which is secured directly to that of the generator 42. In the illustrated example, five fluorescent light units 46 are connected by respective cables 47 to the regulator 45.
Thus, the hydraulic motor 41, generator 42 and ~5 regulator 45 are all arranged in a completely fla~eproof manner, providing a high degree of safety. The cables 47 are connccted to the regulator 5 by conventional gland type 53~:~
connectors, and the regula~or 45 includes a current limiter CiTCUit to ensure that the current flowing through the cables 47 cannot exceed 0.7 amps, to ensure that the ca~les 47 and light units 46 are "intrinsically safe"
Limiting the current in the cables 47 to 0.7 amps ensureS
that any sparking cannot be sufficiently strong to cause an explosion in an atmosphere o-f methane.
In a variation of the arrangement shown in Figure 11, the regulator 45 may be connected to the generator 42 by a flexible electric cable, which again will be "intrinsically safe". The cable between the generator 42 and the regulator 45 will only carry low voltages - for example, 6 volts, 12 volts or, at the very most, 24 volts.
Figure 12 shows one example of a current limiter circuit 50, such as may be used in the regulator 45 of Figure 11.
The current limiter 50 has supply input terminals V+ and V-, across which a Zener diode ZD1 and a resistcr R2 are connected in series. A further resistor R1 is connected between the junction point of the resistor R 2 and Zener diode ZD1 and a control electrode of a Thyristor TH1, which is connected across the supply rails. In the illustrated example, there are provided seven pairs of output terminals OP1 to OP7. The positive terminal of each pair OP1 to OP7 is connected to the main positive rail via a respective fuse F1 to F7 and series diode D1 to D7.
In normal use, current flow simply from the positive supply terminal V+, through the respective fuses F1 to F7 and diode D1 to D7, to the output terminals OP1 to OP7. In the event of the supply voltage rising unacceptably ~5~
high, the Zener diode ZD1 breaks down, to pass currentthrough the resistor R2. The voltage at the control electrode of the Thyristor TH1 then rises, via the resistor R1, to cause the Thyristor TH1 to conduct, and thereby bypass the output terminals OP1 to OP7.
s In the event of serious external loading of the circuit, such that the output voltages at the terminals OP1 to OP7 fall , the fuses F1 to F7 will go open circuit.
If, due to induction3 surges are fed back into the circuit 50 via the output terminals OP1 to OP7, the Zener diode ac~ion will take place, as described above, to cause the Thyristor TH1 to conduct.
The illustrated circuit 50 offers a good degree of current overload protection, against both current and voltage surges, with a very rapid initial reaction time.
~his invention relates to electrical power units, and i8 particularly although not exclusively concerned with electrical power units tha-t are suitable for use in hazardous enviro~ments, such as9 ~r example, in underground mining.
Safety in mines has improved considerably over recent yearsO However~ developments in mining technolog~ led to the use of extremely large and powerful machiner~ at the coal face, and in the v~init~ thereo~.
Due to the nature of mining, ~uch machinery is regularly mo~ed~ Consequentlyj face workers in a modern mine can still face great hazards from the complex of machiner~, ancillary equipment~ cables~ etc.in and around the work areaO
Such hazards are aggravated by the fact thatt despite advances in technology7 it has not ~et been found possible t id lefftlC~ent 1 li hti f 1 f ~ f the potential dangers from moving machinery, regulations rescribe th t electric cab~Veesrl s~eclftl~ volta~eds d ithi specified distance of coal ~aces~ This is because of the high risk o~ rupturing such cables, with the consequent risk of electric shock9 and gas explosion from electric arcs~
~hUg7 face workers have to work in these extremely hazardous areas with virtually no lighting. The risks of accident are therefore gravely accentuated.
~ighting s~s~ems that have bee~ adopted in minin~
environments do tend to have a number of inherent problemsO
~or example, previously proposed wholly electrical systems 3~
have the disadvantage that a high voltage source is required near the point of use, and bulky transformers and converter units are required at frequent intervals along the power distribution system. It is possible only to run five single lamps each of seven watts output from one converter, and it is possible only to run a seven metre length of cable from each converter to each single lamp unit (thus limiting the positional capability of each lamp, with respect to the converter source~. Thus, there are numerous cables required, which can be severed and cause shock or sparking, the cables/liveYcugrrent at 110/125 volts. Such wholly electrical systems require a high consumption of electrical power, and -for transmission of power over 200 metres or more, there is inefficient striking of the lamps, due to power drop.
~15 Another system that has been proposed uses lamp units that are driven by pneumatic power, which power is converted to electrically energy by a generator within the lamp unit.
However9 such a system has not been adopted for a number of reasons. For example, the generators tend to be very bulky, causing the individual lamp units to be bulky, and only single lamp units are available, of relatively poor lighting capability. There is present a high noise level upon starting and during operation of such units, and a large amount of heat is gènerated from each unit in continuous use. There tends to be a rapid power drop of pneumatic power with distance, which severely restricts ~he distances over which light units can be used. Overall, such lamp units tend to be unreliable.
We have also become aware of lamp ~mits similar to the above, but in respect of which it is said that they may be driven by hydraulic power. However, the only design of such lamp units that we have seen can not possibly afford safe running in present day mining conditions, ;~. IL~53~
and has attendant disadvan-tages similar to -the pneumatically driven lamp units mentioned above.
Preferred embodiments of the present inven-tion aim to overcome these disadvantages, by providing reliable ligh-ting units that may be used safely in hazardous conditions.
However, the invention generally is of wider applica-tion.
According to the present invention, there is provided an electrical power unit which comprises an hydraulic mo-tor adap--ted to be connected to a hydraulic circuit having a flow and return line, and an electric generator arranged -to be driven by the motor, the motor and the generator being located wi-thin a flameproof housing and being arranged to provide a d.c. out-put of up to 24 volts and including limiting means, for limit-ing the curren-t supplied by the genera-tor to 0.7~ or less.
It may be appreciated that power units in accordance with the invention can be designed to be safe for use in hazardous areas - e.g. where there is a risk of cable severance or explosive gas. Then, severance of an hydraulic pipe can be of relatively minor consequence. Preferably, means is provided for blocking flow in an hydraulic pipe supplying a power unit in accordance with the invention, in the event of a loss in pressure greater than a predetermined value, as may occur, for example, in a pipe fracture.
Numerous advantages and optional features of the inven-tion will be apparen-t from the following descrip-tion of pre~
ferred embodiments -thereof.
In this specification, the expression "low voltage" is defined as a voltage which is low relative to -that employed previously in mines - i.e. low relative to a vol-tage of 110/125 volts. We believe tha-t the invention is particularly advan-tageous where the power unit provides an output of up to 6 volts, 12 volts, or at the most 24 vol-ts d.c., although the invention is not necessarily limited to these par-ticular figures.
For a better understanding of the invention, and to show how the same may be carried in-to effect, reference will now be made, by way of example, to the accompanying diagrammatic drawings, in which:
. ~
~S3;~
Figure 1 is anhydraulic flow diagram of a lighting system embodying the invention;
Figure ~. is an electrical circuit diagram of a lamp unit embodying the invention;
Figure 3 shows one example of a lamp unit, in cross~section;
Figure 4 shows an.other example of a lamp unit, in cross-section;
Figure 5 shows, in plan view, a coal face provided with a lighting system embodying the invention;
t5 - Figure 6 shows the coal face in front elevation;
Figures 7, 8 and 9 show lamp units fit~ed to respective roof supports or shields as seen respectively on the lines C-C,.B-B and A-A of Figure 5;
Figure 10 is a perspective view of one example of a lamp unit as used in Figures 5.to 9;
.
Figure 11 is a perspective view of another example of a lamp unit; an~
Figure 12 is a circuit diagram of a current limiting circuit of the lamp unit of Figure 11.
In the figures, like reference numerals denote like or corresponding parts.
~ ~ ~ 5 3~
The lighting system illustrated in Figure 1 is suitable for use in underground mining, where it can be used with relative safety. The system comprises a reservoir 1 of hydraulic fluid, and a pump 2 which is arranged to be driven by a motor 3 The motor 3 can be any suitable prime mover, such as/electric or diesel motor, and may be of 40 horse power or less. The pump 2 is arranged to pump hydraulic fluid around the system at a rate of 27.5 gallons per minute, at a pressure of about 1600 P.S.I. A relief valve assembly 6 is provided between flow and return lines 4 and 5, to relieve excess pressure in the system. The /
-53~
parts 1 to 6 thus described afford an hydraulic fluid supply system~ having flow and return ports 7 and 8~
In use, an hydraulic distribution system having flow and rt~urn pipe~ 9 and 10 i5 connected to the ports 7 and 8 of/suppl~ system. At desired intervals 7 there are provided pairs of tees 119 12, etc. in the pipes 9 and 10.
Each tee is provided with a respective non-return valve 139 to pro~ide a connection to the respective flow or return pipe 9 or 10 via the respective teeO A respective lamp unit 14, 15 etCu i8 connected between each pair of tees 11~ 12 etcO, via the one-way valves 13. Each lamp unit 14, 15 etcO compr~s an h~draulic motor which is arranged to drive an electriC generator9 which in turn supplies a respective light.
Figure 2 is an electrical circuit diagram showing one example of a lamp unit 140 '~he lamp unit 14 comprises an hydraulic motor 16, through which h~draulic fluid passes via flow and return lines 17 and 18. The output shaft of th~e hydraulic motor 16 is connected to an electric generator 19 by means ~ a flexible coupling 20. Th0 output of generator 19 is regulated by a regulator 21, and is fed to three ballast units 229 in parallelO Each ballast unit 22 supplies a respective fluorescent tube 230 ~ he hydraulic motor may be of approximately ~ horse power rating~ and have a drive speed in the range 800 to 2000 r,p.mO ~he generator 19 may be a 12 volt - 60 watt DC dynamoO
3o Ballast units 22 and fluorescent tub~ 23 may be of about 8 watts rating.
Figures 3 and 4 show alternative example5 of const~1ction of a lamp unit 14. In ~igure 3, the flow and return hoses 17 and 18 make connection at one end of a housing 24~ to the _ 7 _ hydraulic motor 16. ~he hydraulic motor 16, coupling 20 and electric generator 19 are all mounted in one section of -the housing 24~ and the regulator 21, ballast 22, and tubes 23 are mounted within another section of the housing 24. ~he housing 24 is sealed by a cover 25, in a flameproof and fluid~ight manner.
In Figure 4, a fluorescent tube 23 extends perpendicularly to the axis of the generator 19~ rath~r than parallel to it. In ~igure 4~ there can be seen a glass 26, which seals the housing 24. In both Figures 3 and 4, the electrical circuitr~ ma~ be sunk within epoxy resin ~el~
to protect components from shock load or external vibration transmitted from local machinery, etcO
In the illustrated system, the hydraulic fluid may comprise exclusively oil, or of an emulsion of 60/40 or 95/5 mixture oi.l/water, for example. Alternatively9 the h~draulic fluid may be water alone. In the illustrated arrangement, the hydraulic supply system may be sufficient to light 100 lamp units spaced over a distance of 200 metres.
Within each lamp unit such as 14, it is possible to light either 10 six inch fluorescent tubes, each 4 watt; 5 twelve inch flu~escent tubes9 each 8 watt; 4 twenty-one inch flu~rescent tubes, each 12 watt, or 2 tungsten spotlight units, each 25 wattsO ~ach lamp unit has no external electric circuitry~ and operates on ver~ low voltage - for example, 18 volts maximum across each fluorescent tube.
~ach lamp unit such as 14 may be a hand held inspection lamp, or may be designed for securement to a surface~ ~amp units such as 14 may be fitted into any existing type of equipment which ~s a suitable hydraulic fluid system incorporated therein.
-- 8 ~
In the ~y,stem shown in ~lgure ~ each lamp unit 14~ etc~ may be removed safely from the system without switching off the other lamps in the system. ~lso, each lamp unit ~4 is so designed as to allow any one light within that unit to fail whilst the others within the unit remain lit.
Figures 5 to 9 show how a lighting system as illustrated in ~igure 1 may be installed at a coal face~
A pluralit~ of roof supports and/or roof shields 27 is arranged across a coal face 28, and at face ends 290 Various mining machinery is installed at the coal face, although this machiner~ is not shown in detailO Coal mined from the face 28 is carried away on a stage loader co~ve~or 30q at the main gate 31 to the face 280 An hydraulic pressure-fluid supply system, such as that shown in ~igure 1 (parts 1 to 6) is mounted on the stage loaderT
A lamp unit 3Z (equivalent to the lamp units 149 15, etc) is mounted o~ each of the roof supports 27, and is connected to flow and return pipes supplied by the hydraulic pressure-fluid suppl~ s~stem 330 ~ach lamp unit 32 is arranged to light both the gallery ~ and the coal face ~8~ A face conveyor 40 conveys coal from the face 28 to the stage loader conve~or Figure 10 illustrates one example of la~p units 32 ~ach lamp unit 32 has a totally sealed flameproof housing 35 At a centre part of the housing 359 there are provided flow, 3o and return ports 36 and 37~ which lead to an hydraulic motor and electrical generator within the housing 350 ~t one side 38 of the housing 35~ there are mounted two fluorescent tubes which are arranged to project light downwardly9 as shown by the arrow ~0 At an opposite side 39 of the housing 35~ there are mounted three fluorescent tubes~ which are respectively _ 9 _ arranged to project light horizontallyg obliquely downwardly9 and vertically downwardly, as shown by the arrows Bp C and Do ~he housing 35 is arranged to be secured to the canopy of a roof support 27, as shown in Figures 5 to 9~ such that the two tubes at the side 38 of the housing 35 project light downwardly into the gallery 34, whilst the three tubes at the opposite side 39 project light into the coal face 280 It may be appreciated that the illustrated arrangements pr~vide a lighting system which is inherently safe for use in hazardous areas, such as are found in mines9 chemical storage vessels, and areas where chemicals or gaseous elements existp Experiments have shown that lamp units as illustrated can have excellent light output, whilst being of relatively modest power consumption, and light in weight~ At any particular installation, an hydraulic fluid distrubution system may be supplied with tees such as 11 and 12 at any desired intervals, such that inspection lamp units or semi-permanent lamp units may be connected thereto as desired. Preferably~ the hydraulic pressure-fluid s`upply system is provided with means for blocking flow in the flow and return pipes9 in -the event of a loss in pressure greater than a predetermined value~ as may occur~
for`example, in a pipe fracture~ ~hus, in the event of a fracture of an hydraulic pipe in the illustrated system~
potentially the most serious event would simply be loss of light~ The arrangement may be such thatS in the event of such light loss9 associated m~hiner~ is automatically turned of~.
3o As noted above, lamp units in accordance with the invention may be provided integrally on apparatus which has its own suitable supply of hydraulic pressure-fluid~ such as, for example, a powered roof support.
53~:~
Although the illustrated arrangements are concerned with lighting units, it ma~ be appreciated that the in-vention may be exten~ed to provide portable power units for any requirementO ~or example~ each housing 24 may contain any desired electricall~ driven device or apparatus~ Alternatively~
each housing 24 may be provided with electric terminals for connec-tion to electrically driven apparatusO Such units may advantageousl~ proyide an electrical suppl~ at low vo~ge, in ~ safe and convenient mannerO
As an alternative to the h~draulic pressuxe fluid suppl~ system shown in Figure 1~ there may be provided two 20 horse power motors, each driving a respective pump - and i~dependent hydraulic fluid distribution system? the two pumps being supplied ~rom the common reservoir 1.
The two hydraulic fluid distribution s~stems are preferabl~
interlaced in a lighting s~stemO ~hen~ in the event of failure of one of the distribution ~ystems, only a portion (e~gO a half) of the lights in the lighting system may be extinguished. ~his is p~rticularly advantageous from the aspect of safety.
The alternative lamp unit 40 which is shown in Figure 11 comprises an hydraulic motor 41 and an electric `25 generator 42, each of which is disposed within its own flameproof housing, which housings are bolted one to the other. Flow and return hoses 43 and 44 are connected to the hydraulic motor 410 A current regulator 45 is disposed in its own flameproof housing, which is secured directly to that of the generator 42. In the illustrated example, five fluorescent light units 46 are connected by respective cables 47 to the regulator 45.
Thus, the hydraulic motor 41, generator 42 and ~5 regulator 45 are all arranged in a completely fla~eproof manner, providing a high degree of safety. The cables 47 are connccted to the regulator 5 by conventional gland type 53~:~
connectors, and the regula~or 45 includes a current limiter CiTCUit to ensure that the current flowing through the cables 47 cannot exceed 0.7 amps, to ensure that the ca~les 47 and light units 46 are "intrinsically safe"
Limiting the current in the cables 47 to 0.7 amps ensureS
that any sparking cannot be sufficiently strong to cause an explosion in an atmosphere o-f methane.
In a variation of the arrangement shown in Figure 11, the regulator 45 may be connected to the generator 42 by a flexible electric cable, which again will be "intrinsically safe". The cable between the generator 42 and the regulator 45 will only carry low voltages - for example, 6 volts, 12 volts or, at the very most, 24 volts.
Figure 12 shows one example of a current limiter circuit 50, such as may be used in the regulator 45 of Figure 11.
The current limiter 50 has supply input terminals V+ and V-, across which a Zener diode ZD1 and a resistcr R2 are connected in series. A further resistor R1 is connected between the junction point of the resistor R 2 and Zener diode ZD1 and a control electrode of a Thyristor TH1, which is connected across the supply rails. In the illustrated example, there are provided seven pairs of output terminals OP1 to OP7. The positive terminal of each pair OP1 to OP7 is connected to the main positive rail via a respective fuse F1 to F7 and series diode D1 to D7.
In normal use, current flow simply from the positive supply terminal V+, through the respective fuses F1 to F7 and diode D1 to D7, to the output terminals OP1 to OP7. In the event of the supply voltage rising unacceptably ~5~
high, the Zener diode ZD1 breaks down, to pass currentthrough the resistor R2. The voltage at the control electrode of the Thyristor TH1 then rises, via the resistor R1, to cause the Thyristor TH1 to conduct, and thereby bypass the output terminals OP1 to OP7.
s In the event of serious external loading of the circuit, such that the output voltages at the terminals OP1 to OP7 fall , the fuses F1 to F7 will go open circuit.
If, due to induction3 surges are fed back into the circuit 50 via the output terminals OP1 to OP7, the Zener diode ac~ion will take place, as described above, to cause the Thyristor TH1 to conduct.
The illustrated circuit 50 offers a good degree of current overload protection, against both current and voltage surges, with a very rapid initial reaction time.
Claims (26)
1. An electrical power unit comprising an hy-draulic motor adapted to be connected to a hydraulic circuit having a flow and return line, and an electric generator arranged to be driven by the motor, the motor and the gen-erator being located within a flameproof housing and being arranged to provide a d.c. output of up to 24 volts and including limiting means for limiting the current supplied by said generator to 0.7A or less.
2. A power unit according to claim 1, wherein said output is up to 12v d.c.
3. A power unit according to claim 1, wherein said output is up to 6v d.c.
4. A power unit according to claim 1, 2 or 3, wherein said limiter means is disposed within a flameproof housing.
5. A power unit according to claim 1, 2 or 3, wherein said limiter means is disposed in a housing separate from that of said generator, to which said limiter means is connected by means of a cable extending between the res-pective housings.
6. A power unit according to claim 1, 2 or 3, having electrical components which are sunk in resin within a housing of said unit.
7. A power unit according to claim 1 including an electric light connected to said generator.
8. A power unit according to claim 7, wherein said light comprises at least one fluorescent light element.
9. A power unit according to claim 8, wherein said light element is disposed within a flameproof housing.
10. A power unit according to claim 9, including a flameproof housing, wherein said light element is disposed within said common flameproof housing with said motor and generator.
11. A power unit according to claim 1 including a plurality of discrete electric lights each supplied via a respective cable.
12. A power unit according to claim 11, wherein said lights include at least one hand held lamp.
13. A power unit according to claim 12, wherein said lights include at least one lamp unit mounted in or on an hydraulically operated machine.
14. A power unit according to claim 11, wherein said lights include at least one lamp unit having at least three fluorescent tubes, arranged to project light res-pectively horizontally, obliquely downwardly, and vertically downwardly.
15. A power unit according to claim 1, 2 or 3, including an electrical connector for connecting said gen-erator to external electrical apparatus.
16. An hydraulic fluid distribution system pro-vided with a plurality of power units according to claim 1, the system having a plurality of connection points to any one of which any one of the power units may be selec-tively connected.
17. A system according to claim 16, having two independent hydraulic circuits each having a plurality of said connection points, the connection points of one cir-cuit being interlaced with those of the other.
18. A system according to claim 17 including means for blocking flow in at least part of the system in the event of a loss of pressure greater than a predeter-mined value.
19. A system according to claim 18 including control means adapted to inhibit operation of associated machinery in the event of a power drop in the system.
20. A system according to claim 19, wherein the hydraulic fluid is water which is free from additives, apart from impurities.
21. Hydraulically operated machinery provided with or in combination with a power unit according to claim 1.
22. Hydraulically operated machinery provided with or in combination with an hydraulic fluid distribution system according to claim 16.
23. Machinery according to claim 21, wherein a respective said power unit is disposed in at least one housing provided integrally on said machinery.
24. Machinery according to claim 23, wherein said machinery is mining machinery.
25. Machinery according to claim 24, wherein said machinery comprises a powered roof support.
26. Machinery according to claim 24, wherein at least one said power unit is connected to the hydraulic circuit of the machinery.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB81.07844 | 1981-03-12 | ||
| GB8107844 | 1981-03-12 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1185321A true CA1185321A (en) | 1985-04-09 |
Family
ID=10520348
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000398274A Expired CA1185321A (en) | 1981-03-12 | 1982-03-12 | Hydraulic motor driven electric generating unit |
Country Status (5)
| Country | Link |
|---|---|
| EP (1) | EP0073785A1 (en) |
| CA (1) | CA1185321A (en) |
| GB (1) | GB2113015B (en) |
| WO (1) | WO1982003260A1 (en) |
| ZA (1) | ZA821685B (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB8820140D0 (en) * | 1988-08-24 | 1988-09-28 | Mcginn T | Electrical supply system for low current loads |
| GB2230392A (en) * | 1989-02-04 | 1990-10-17 | Ruder Oscar Younge | Power supply system for use in a hazardous environment |
| FR2703132B1 (en) * | 1993-03-24 | 1995-06-09 | Siraga Sa | CAROUSEL FOR FILLING GAS BOTTLES, COMPRISING MEANS OF PRODUCING ELECTRIC CURRENT. |
| US6568493B2 (en) * | 2001-07-13 | 2003-05-27 | Mark Joesph Parkert | Skid-steer loader power source attachment and method of manufacture |
| WO2014035373A1 (en) | 2012-08-28 | 2014-03-06 | Micro Motion, Inc. | Flameproof housing with display |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2203867A (en) * | 1938-01-12 | 1940-06-11 | Luis G Legorreta | Protective device for electric circuits |
| US3317792A (en) * | 1964-03-20 | 1967-05-02 | Westinghouse Electric Corp | Load protection circuit |
| GB1215885A (en) * | 1968-03-06 | 1970-12-16 | Oldham & Son Ltd | Improvements in or relating to lighting units for use with hydraulic equipment |
-
1982
- 1982-03-12 WO PCT/GB1982/000085 patent/WO1982003260A1/en not_active Ceased
- 1982-03-12 ZA ZA821685A patent/ZA821685B/en unknown
- 1982-03-12 EP EP82900655A patent/EP0073785A1/en not_active Withdrawn
- 1982-03-12 CA CA000398274A patent/CA1185321A/en not_active Expired
- 1982-03-12 GB GB08231471A patent/GB2113015B/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| EP0073785A1 (en) | 1983-03-16 |
| ZA821685B (en) | 1983-09-28 |
| GB2113015B (en) | 1985-06-05 |
| WO1982003260A1 (en) | 1982-09-30 |
| GB2113015A (en) | 1983-07-27 |
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| Date | Code | Title | Description |
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| MKEX | Expiry |