GB2214722A - Conjoint cooling of electric motor and its controller - Google Patents

Abstract

An electric motor arrangement including an electronic controller (7) mounted on the motor (1) and including means, e.g. a fan (23), for directing a flow of cooling air over both a surface of the motor (1) and a surface of the controller (7). The fan (23) is suitably mounted at one end of the motor (1) and directs the air flow along a space extending axially between the motor casing (3) and the controller casing (9). The motor casing (3) is suitably of cylindrical form and coaxially surrounded by a tubular member (17) spaced from the motor casing (3) so as to provide in the space between the motor casing (3) and the controller casing (9) a first axial channel (27) between the motor casing (3) and a tubular member (17) and a second such channel (29) between the tubular member (17) and the contoller casing (9). <IMAGE>

Description

Electric motor arrangements This invention relates to electric motor arrangements.

More particularly the invention relates to electric motor arrangements comprising an electric motor and an electronic controller mounted on the motor, e.g. for controlling the speed of the motor.

It is an object of the present invention to provide such an electric motor arrangement further including means for cooling both the motor and the controller.

According to the present invention there is provided an electric motor arrangement comprising: an electric motor; an electronic controller mounted on the motor; and means for directing a flow of fluid from an ambient atmosphere both over a first surface in good thermal contact with said motor and over a second surface in good thermal~conta-c't~-wit} said contr6l 1 er.

Normally~'said'flu'id is'~äir.

Said first and second surfaces are~suitably an external surface of a casing for the motor and an external surface of a housing for the controller respectively.

Preferably said means for directing includes fan means for producing said flow of said fluid.

In one particular embodiment of the invention said motor has a casing of generally cylindrical form; and said means for directing comprises a tubular member coaxially surrounding the motor casing so as to define a first channel between the external surface of the casing and the internal surface of said tubular member and a second channel between the external surface of said tubular member and the external surface of part of a housing for said controller; and fan means for producing a flow of said fluid through both said first channel and said second channel.

Alternatively or additionally said part of said housing may be provided with at least one aperture to allow said fluid to flow through said housing.

In the above-mentioned particular embodiment of the invention said tubular member helps to shield the controller from heat produced by the motor, more especially when the controller Is mounted on top of the motor. This can be particularly advantageous if the fan means ceases to operate for any reason.

The fan means is suitably driven by an electric motor separate from the main motor. Alternatively, the fan means may be driven by the main motor itself.

One electric motor arrangement in accordance with the invention will now be described, by way of example, with reference to the accompanying drawings in which: Figure 1 is a partly cut away side view of the arrangement; and Figures 2 and 3 are views of the opposite ends of the arrangement.

Referring to the drawings, the arrangement includes an electric motor 1 having a cylindrical casing 3 and an output drive shaft 5 extending from both ends of the motor casing 3.

An electric controller 7-for controlling the speed of the motor 1 is mounted on top of the motor 1 by means of a mounting plate 9 which is bolted by way of flanges 9A to brackets 11 which in turn are bolted to the motor casing 3. The mounting plate 9 also constitutes the base of a rectangular housing 13 for the controller 7, and is made sufficiently massive to serve as a heat sink for the controller. The brackets 11, together with further brackets 15 serve to support a tubular member 17 coaxially surrounding the curved part of the external surface of the motor casing 3 and spaced therefrom, the member 17 having secured to it a base plate 19 for mounting the whole motor arrangement.

At one end the member 17 extends beyond the corresponding end of the motor casing 3, as does the mounting plate 9. At this end the mounting plate 9 and member 17 are closed off by an end plate 21. In an aperture extending through the upper part of the end plate 21, above the motor drive shaft 5, there is mounted an axial flow fan 23 driven by an electric motor separate from the motor 1, the fan 23 being provided with a replaceable dust filter 25 at its inlet end.

To accommodate the fan 23, a part of the member 17 Is cut away.

The fan 23 is positioned so that it drives air both through an annular first channel 27 formed between the external surface of the motor casing 3 and the internal surface of the member 17, and through a second channel 29 formed between the bottom of the mounting plate 9 and the external surface of the upper part of the member 17, as indicated by arrows in Figure 1. Fins 31 formed on the bottom of the mounting plate 9 extend downwardly into the second channel 29. In addition, an aperture 33 Is provided in the mounting plate 9 to allow air from the second channel 29 to pass through the controller housing 13.

Connection of the controller 7 to an electric supply is made by way of a cable 35 passing through a gland 37 provided in a flange 9A of the mounting plate 9, and electrical connections between the controller 7 and the motor 1 and the fan 23 are made by way of further cables 39 and 41.

A further gland 39 is provided in the other flange 9A to accommodate a cable (not shown) connecting the controller 7 with a remote control unit (not shown) for the arrangement, if required.

In operation the motor 1 is cooled by the flow of ambient air produced by the fan 23 through the first channel 27 over the external surface of the motor casing 3, and the controller 7 is cooled by the flow of ambient air produced by the fan 23 through the second channel over the fins 29 and through the interior of the controller housing 13. The tubular member 17 serves to shield the controller 7 from heat produced in the motor 1 which is particularly advantageous if for any reason the fan 23 should stop operating.

If the arrangement is operated in a reasonably safe environment, part of the controller housing 13, e.g. the top, may be dispensed with to assist in cooling the controller 7.

To Improve cooling of the motor fins (not shown) may be provided on the external surface of the motor casing 3 so as to project into the space 27. Furthermore, if the motor 1 Is not required to be totally enclosed, apertures (not shown) may be provided in the motor casing 3 to improve cooling of the motor.

In alternative arrangements according to the invention the controller may be mounted underneath, or to one side of the motor, instead of on top of the motor.

In such arrangements the air flow may be directed across the surface of a wall or walls of the controller housing other than the base of the housing.

In other alternative arrangements the controller may be mounted at one end of the motor and the air flow directed so as to cool the controller before or after flowing over the external surface of the motor casing.

The fan may be of the circumferential flow type, instead of the axial flow type. Moreover, the fan may be driven from the shaft of the motor 1, instead of by a separate electric motor, e.g. where the motor speed range is small.

Claims (11)

1. An electric motor arrangement comprising: an electric motor; an electronic controller mounted on the motor; and means for directing a flow of fluid from an ambient atmosphere both over a first surface in good thermal contact with said motor and over a second surface in good thermal contact with said controller.

2. An arrangement according to Claim 1 wherein said controller is mounted on top of said motor.

3. An arrangement according to Claim 1 or Claim 2 wherein said first and second surfaces are an external surface of a casing for the motor and an external surface of a housing for the controller respecti vely.

4. An arrangement according to any one of the preceding claims wherein said means for directing includes fan means for producing said flow of said fluid.

5. An arrangement according to Claim 3 wherein said motor casing is of generally cylindrical form; and said means for directing comprises a tubular member coaxially surrounding the motor casing so as to define a first channel between the external surface of the casing and the internal surface of said member and a second channel between the external surface of said tubular member and the external surface of said housing for the controller; and fan means for producing a flow of said fluid through bpth said first channel and said second channel.

6. An arrangement according to Claim 5 wherein said part of said housing is provided with fins extending into said second channel.

7. An arrangement according to Claim 5 or Claim 6 wherein said part of said housing is provided with at least one aperture to allow said fluid to flow through said housing.

8. An arrangement according to any one of Claims 4 to 7 wherein said fan means is driven by an electric motor separate from said first-mentioned electric motor.

9. An arrangement according to any one of Claims 4 to 7 wherein said fan means is driven by said electric motor.

10. An arrangement according to any one of Claims 4 to 9 wherein said fan means is an axial flow fan.

11. An electric motor arrangement according to Claim 1 substantially as hereinbefore described with reference to the accompanying drawings.