GB2185551A

GB2185551A - A power transmission system

Info

Publication number: GB2185551A
Application number: GB08700809A
Authority: GB
Inventors: Mark Barnes Glossop; Andrew John Walker
Original assignee: Dowty Meco Ltd
Current assignee: Dowty Meco Ltd
Priority date: 1986-01-18
Filing date: 1987-01-15
Publication date: 1987-07-22
Also published as: GB8601192D0; AU6752487A; ZA87171B; GB8700809D0

Abstract

A power transmission system comprises a motor (11,111,211), a gearbox (14,114,214) having an input shaft (17,117,217) which is drivingly connected to the motor by means of a coupling (12,112,212), and a cooling means having a fan with an impeller (21,121,221) to cool the gearbox. The impeller (21,121,221) may be mounted on either the motor's rotor or the input shaft of the gearbox. In certain embodiments the impeller (21,121,221) is housed in the same casing (13,113,213) as the coupling (12,112,212). The system may further comprise a heat exchanger (30,40) which provides a high surface area for cooling off the gearbox directly or indirectly, through or over which air is caused to flow by the action of the impeller (21,121,221). <IMAGE>

Description

SPECIFICATION Power transmission system This invention relates to a powertransmission system and in particular to a powertranamission system for use with an armoured face conveyor in, for example, a mine.

It is well known to provide powertransmission systems having a gearbox which incorporates means for cooling lubricant used in the gearbox. One particular cooling means includes a heat exchanger against which the lubricant is splashed by the gearing of the gearbox during motion thereof. Cooling water is circulated around one side of this heat exchanger so as to extract heat from the lubricant and dissipate it by circulating it around the other side of the heat exchanger.

The use of water to effect the cooling of the gearbox in this manner increases the demand on water at the coal face and adds an extra complication to the water supplytherefor. ltwouldtherefor be advantageous to provide a powertransmission system in which cooling does not involve the use of water.

In accordance with the present invention there is provided a powertransmission system comprisng a gearbox having an input shaft; a motor which is driveably connected to said input shaft by a coupling and cooling means to cool the gearbox, wherein the cooling means is a fan connected to and driven by the motor. Preferably the coupling isaflexiblecoupi- ing.

By providing a power transmission system in ac cordance with the present invention air is used as the coolant and the demand forthewaterto fulfill this aspect is removed.

In mines in particular, it is advantageous to use a compact hig h high horsepowermininggearboxandare- latively small motor to drive the conveyors at or near the mine face. Several suitable motors are already availableto fulfill this function, and any ofthese motors can be used in the present powertransmission system. The motor preferably includes a rotor and may advantageously be a two (or more) speed motor.

Previously, the use of air as a coolant has been a problem with these high horse power mining gearboxes because bythevery nature oftheirfunction and use they must be small. Therefore at high horsepowers the surface area to volume ratio, which dictates the cooling characteristics of the gearbox, is too low to ensure sufficient cooling of the gearbox.

These problems are generally overcome in the present power transmission system.

The flexible coupling used with this type of power transmission system is present to ensure an efficient transfer of rotational power from the motor to the input shaft of the gearbox. This coupling is preferably, either a fluid coupling our a pin type flexible coupling.

The fan ofthe cooling means preferably includes an impeller which is mounted on and driven by the rotor of the motor. As an alternative to the direct motor drive mentioned, the impeller is preferably mounted on and driven by the input shaft of the gearbox.

By mounting the fan impeller in such a manner, it is possible to locate the cooling means in the same housing as the coupling and thereby save on space.

The cooling means mayfurther include a heat ex- changer means having at least one passageway formed therein through which oil from the gearbox may be passed before being returned to the gearbox.

In order for effective cooling of the gearbox oil to occur, it is necessary to provide the heat exchanger with a sufficiently large surface area and an adequate through-flowof coolant, in this case air.

The surface area required in any such cooling means is determined by the relative inefficiency of the gearbox and as a resultthe rotational energy dissipated in friction and therefore heat. If more suface area is required this is preferably provided in the form of a honeycomb structure radiatorthrough which air is caused to flow bythefan.

Any radiator employed may have the cooling air either sucked or blown therethrough, and is moun tedneartothefan impellertoensuremaximumflow efficiency.

The cooling surface area required is affected by the volume and speed of airflow, the requirement being reduced at higher airvolume flows. It is possible, therefore, to reduce the surface area required in the radiator, by increasing the fan impeller size and thereby the volume airflow. The exact combination of fan impeller size to surface area requirement of the radiator is therefore a careful balance of costs, and size of motor.In cases where the cooling surface area requirement is not large, a simple cooling coil may provide a large enough surface area for affective cooling The invention will now be described by way of example with reference to the accompanying drawings ofwhich:- Figure lisa partially cut-away plan view of a power transmission system according to a first embodiment of the invention, Figure 2 is a partially cut-away plan view of a power transmission system according to a second embodimentofthe invention, Figure3 is a partially cut-away plan view of a power transmission system showing minor amendments to the second embodiment of the invention as shown in Figure 2 and, Figure 4 is a partially cut-away view of an alternative airflow arrangement for a powertransmission system according to the second embodiment of the invention as shown in Figure 2.

With reference to Figure 1 there is shown a motor 11 having a rotatable rotor and stationary stator members (not shown), the output from the rotor being connected to input shaft 17 of a gearbox 14by afluid coupling 12. Thefluid coupling 12 is housed in a casing 13 which physically connects the motor to the gearbox 14. The casing 13 also houses a fan having an impeller21 which providesthecoolingforthe gearbox 14.

The gearbox 14 includes a housing 15 supporting gearing of the gearbox, said gearing being in the form of a number of gears 16 which transmit rotati onal energy supplied to the input shaft 17 bythe motor 1 1.The gears 16 therefore operably connect the input shaft 17 ofthe gearbox 14to an outputshaft 18, which may be used to connect the gearbox 14via sprockets (not shown) to the chain or chains of an armoured face conveyor (not shown) in a mine.

The input shaft 17 of the gearbox 14 is connected to the output ofthe fluid coupling 12 to form a driveable connection between the motor 11 and the gearbox 14.

The housing 15 is provided with a number of ribs orfins 19 which extend therefrom so as to increase its external surface area and thereby improve the cooling characteristics ofthe gearbox. Further, the housing has a duct 20 provided in the walithereof.

The gearbox 14 is provided with cooling means in the form ofafan,which has an impeller21 which is mounted on and driven by the input shaft 17 ofthe gearbox 14.

Rotation of the in put shaft 17 rotates the impeller 21 and causes airto be drawn into the casing 13 through an aperture 22. The air is caused to circulate around the gearbox to provide cooling and is eventually exhausted from the casing 13, via the duct 20, at a point near the fins 19 to provide a cooling effect thereto.

A second embodiment ofthe invention is shown in Figure 2 in which the last two digits of the reference numerals correspond to the numerals shown in Figure 1 forthesameorsimilarcomponents.

The embodiment of Figure 2 has a motor 111 ,fluid coupling 112, casing 113which housesthefluid coupling, gearbox 114, input shaft 1 to the gearbox and fan impeller 121. The powertransmission system is assembled in the similar mannerto that described with reference to Figure 1 and comprises a motor 111 which drives a fluid coupling 112 housed within a casing 113, the fluid coupling 112 being driveably connectedtothe inputshaft 117 of a gearbox 114. The sytem further comprises a heat ex changer in the form of a honeycomb structured radiator 30 which has several pipes, each of which fluid mayflowthrough,forming one side of the heat ex changer and is shaped so asto allowairto pass around side pipes to effect cooling.

This radiator is connected to the motor 111 buy a cowl 31 which encircles thefan impeller 121 mounted onthe rotorofthe motor 111 and guidestheflow ofairthrough said radiator.

Oil from the gearbox 114 is fed to the pipes ofthe radiator 30 by means of a supply pipe 32 and after passing through the radiator is returned to the gearbox 114 by return pipe33. Circulation of oil around the radiator is encouraged by a circulation pump 34.

During operation ofthe powertransmission system the fan impeller 121 will drawairthroughthe radiator30 as well as causing the flow ofairoverthe motor 111 with the cowl 31 guiding this airflow, The air drawn through the radiator 30 cools the oil which is passed through the pipes of the radiator and con sequentlythe operating temperature ofthe gearbox 114 is reduced.

Referring now to Figures 3 and 4, which show minor amendments to the second embodiment of the invention and in which the last two digits of the reference numerals correspond to the numerals shown in Figures 1 and2forthesameorsimilar parts.

The embodiment of Figure 3 and 4 has motor 211, fluid coupling 212, casing 213 which houses the fluid coupling, inputshaft2l7 ofthe gearbox 214 andfan impellar221.

The power transmission comprises a motor 211 driving a fluid coupling 212 housed within a casing 213, the fluid coupling drivingly connects the 211 to an input shaft 217 of a gearbox 214. Afan having an impellar 221 is mounted upon and driven bythe inputshaft217.

A heat exchanger in the form of a cooling coil 40 which is made from finned tube is also housed within and supported by the casing 213. One end of the cooling coil 40 is connected to a suppiy pipe 42 and the other end is connected to a return pipe 43 through a manifold block (not shown). The oil used in the gearbox is encouraged to flow through the cooling coil 40 by a circulation pump 44.

In the assembly shown in Figure 3, the casing 213 has an aperture 222 to allowairto enterand afurther aperture 41 to allowairto exitthe casing 213 after passing around the coil 40.

In the assembly shown in Figure 4, two independent sets of apertures 45,46 are provided in the wall ofthe casing 213. Underthefan impeller 221 air is drawn into the casing via the action of apertures 45 and caused to circulate around the cooling 40 before being forced out of apertures 46. In this arrangement the airflow is iocalised around the cooling coil whereas in the arrangement shown in Figure 3 air must traverse the casing to exit.

During operation ofthe powertransmission system the fan 221 will draw air over the cooling coil 40 through which oil from the gearbox 214 is passed.

The passages of air over the cooling coil 40 coolsthe oil passing through the coil and consequently the operating temperature of the gearbox 214 is reduced.

Claims

1. A powertransmission system comprising a gearbox having an input shaft; a motor which is driveably connected to said input shaft by a coupling and cooling meanstocoolthegearboxwhereinthe cooling means is a fan connected to and driven by the motor.

2. A powertransmission system as claimed in claim 1,wherein the coupling is a flexible coupling.

3. Apowertransmission system as claimed in claim 2, wherein the flexible coupling is a fluid coupling.

4. A power transmission system as claimed in claim 2, wherein the flexible coupling is a pin type flexible coupling.

5. A power transmission system as claimed in any one of claims 1 to 4 wherein the motor has a rotorandthefan comprises an impellerwhich is mounted on and driven by said rotor

6. A power transmission system as claimed in any one of claims 1 to 4 wherein the fan comprises an impellerwhich is mounted on and driven by the inputshaftofthegearbox.

7. A power transmission system as claimed in any one ofthe preceding claims wherein the cooling means includes a heat exchanger means having at least one passageway formed therein through which oil from the gearbox may be passed before being returned to the gearbox.

8. A powertransmission as claimed in claim 7 in which the heat exchanger means is a honeycomb structure radiatorthrough which air is caused toflow bythefan.

9. Apowertransmission as hereinbeforedescribed with reference to any one of figures 1 -4.