GB2099229A

GB2099229A - Rotary dynamoelectric machine

Info

Publication number: GB2099229A
Application number: GB8116049A
Authority: GB
Original assignee: MCCLURE DAVID Ltd
Current assignee: MCCLURE DAVID Ltd
Priority date: 1981-05-26
Filing date: 1981-05-26
Publication date: 1982-12-01

Abstract

A rotary dynamoelectric machine such as an electric motor has an armature or rotor provided with ducts through which fluid may be passed to cool the armature or rotor. The ducts may comprise an axial bore 8, radially extending passages 14, ducts 9 disposed near to the surface of a rotor, radial passages 15 and an axial outlet 16. <IMAGE>

Description

SPECIFICATION Rotary dynamoelectric machines This invention relates to rotary dynamoelectric machines and finds particular but not exclusive application to electric motors.

It is often important that rotary dynamoelectric machines are totally enclosed in a casing, for example in the mining industry where electrical sparks can ignite explosive gases in the atmosphere, or in corrosive or dust laden atmospheres where corrosion or occlusion of the components of the machine may occur. Cooling of such enclosed machines by conduction through their casings is often inadequate and external water-cooled jackets have been proposed for use with AC powered electric motors.

According to the present invention a rotary dynamoelectric machine has an armature or rotor which is provided with ducts through which fluid may be passed to cool the armature or rotor.

Provision of cooling ducts in accordance with the invention permits a reduction in size and weight compared to externally cooled machines.

A preferred arrangement of ducts incorporates a duct extending along the axis of the core communicating with a plurality of ducts extending near the surface of the core and parallel to its axis.

An alternative arrangement incorporates a duct extending along the axis of the core communicating with a plurality of ducts extending near to the surface of the core the latter ducts being disposed in a spiral configuration around said axis. The latter arrangement serves to pump the coolant fluid through the ducts when the armature is rotated but suffers from the disadvantage that pumping is only obtained when the armature is rotated in one direction depending on the direction of the spiral.

In a preferred embodiment of the invention an outer duct is disposed concentrically around said axially extending duct but has a greater diameter than the latter, the inner duct extending from an inlet to the end of the core remote from the inlet, and the outer duct extending from an outlet generally concentric with the inlet to the end of the core adjacent the inlet.

Communication between the axially extending ducts and the ducts near to the surface of the core is preferably by means of a plurality of radially extending ducts.

In an alternative preferred embodiment the axial ducts of the previous embodiment are omitted and replaced by a pair of ducts extending away from the core along the axis of the core, each from a respective end of the latter.

In this embodiment coolant fluid is circulated into one end of the core, through the core near to its surface and out of the other end.

The invention may be better appreciated from the following description by way of an example with reference to Figures 1 to 3 of the accompanying drawings, of a 30 HP DC electric motor constructed in accordance with the invention.

Figure 'shows a cross sectional view through an electric motor in accordance with the invention; Figure 2 is a cross sectional view along the line X-X of Figure 1 through the core of the armature of the electric motor; Figure 3 is a cross sectional view along the line Y-Y of Figure 1 through another portion of the core of the armature of the electric motor.

The motor illustrated in Figures 1 and 2 comprises field windings 1 disposed in a sealed casing 2. The armature comprises a core 3 and windings 4 and is mounted for axial rotation on bearings (5,6). A shaft (7) protrudes through the casing 2 to transmit the power produced by the motor.

A network of ducts is provided for conduction of coolant water through the core. Any other coolant fluid may be enmployed, for example oil or any other liquid, air, nitrogen or any other suitable gas.

The network comprises an axial bore 8 which extends from an input 12 through the bearing 6 remote from the shaft 7 along the length of the core.

Twelve ducts 9 extend parallel to the axial bore 8 close to the surface of the core and substantially along its entire length. Any other convenient number of ducts 9 may be provided. Communication between the ducts 9 is provided by annular ducts (10, 11) at each end thereof. This is illustrated in Figure 2.

Six, or any other convenient number, of radially extending ducts 14 are disposed near the end of the core adjacent the output shaft 7, between the axial bore 8 and the annular duct 10. An output duct 13 concentric with and having a greater diameter than the inlet of the axial bore 12, extends from the inlet 12 to six or any other convenient number of radially extending ducts (15) which communicate with the annular duct (11) (Figure 2).

The network through which coolant may be circulated therefore consecutively comprises an input 12, the axial bore 8, radial ducts 14, annular duct 10, the twelve ducts (9), annular duct 11, radial ducts 15, the output duct 13 leading to an outlet 16. The inlet 12 and outlet 16 communicate with a gland (not shown) of any convenient construction, which facilitates connection of the rotatable core to a source and receiver of the coolant fluid.

The outlet 16 is disposed at a greater radius from the axis of rotation than is the inlet 12. The action of centrifugal force on a fluid disposed in the network of ducts will, during use of the motor urge fluid to flow from the inlet to the outlet with the effect of pumping fluid around the network of ducts, thereby reducing the need for an external pumping means.

In an alternative embodiment of the invention which is not illustrated, the axial ducts 13 and 8 are omitted and are replaced by axial bores extending respectively through the bearings 6 to the radial ducts 15 and through the bearings 5 to the radial ducts 14. Coolant may therefore be circulated through the axial duct passing through the bearing 5,throughthenetwork14,10,9,11,15andthrough the bore passing through the bearing 6 or vice versa.

The outlet may be arranged at a greater distance from the axis than the inlet so that a pumping action analogous to that described with reference to Figure 1 is obtained.

In further alternative embodiments the ducts 9 do not extend parallel to the axis of the core but extend in spiral configuration near to the surface of the core.

Such embodiments may only be used for rotation in one direction.

A 30 HP DC electric motor constructed in accordance with the accompanying drawings having a core 30 cm in length and 12 cm in diameter may dissipate approximately 2.5kw from the surrounding aramture.

The invention finds similar application to the armatures of dynamos, alternators, AC motors or other dynamoelectric machines.

Claims

1. A rotary dynamoelectric machine including an armature or rotor provided with ducts through which fluid may be passed in use to cool the armature or rotor.

2. A rotary dynamoelectric machine as claimed in claim 1, wherein a duct extends along the axis of the rotor and communicates with one or more ducts extending near to the surface of the rotor.

3. A rotary dynamoelectric machine as claimed in claim 2, wherein said one or more ducts extending near to the surface of the rotor extend parallel to the axis of the rotor.

4. A rotary dynamoelectric machine as claimed in claim 2, wherein said ducts extending near the surface of the rotor, are disposed in a spiral configuration.

5. A rotary dynamoelectric machine as claimed in any preceding claim, wherein fluid is pumped through the ducts when the rotor rotates.

6. A rotary dynamoelectric machine as claimed in any preceding claim, wherein an outer duct is disposed concentrically around an axially extending duct.

7. A rotary dynamoelectric machine as claimed in claim 6, wherein said outer duct has a greater diameter than said axially extending duct.

8. A rotary dynamoelectric machine as claimed in any preceding claim, wherein the axially extending duct extends from an inletto an end ofthe rotor remote from said inlet.

9. A rotary dynamoelectric machine as claimed in claim 8, wherein said outer duct extends from an outlet generally concentric with said inlet to the end of the core remote from the inlet.

10. A rotary dynamoelectric machine as claimed in any of the claims 2 to 9, wherein the axially extending duct and the ducts near to the surface of the rotor communicate by means of a plurality of radially extending ducts.

11. A rotary dynamoelectric machine as claimed in claim 1, wherein a duct extends axially through a bearing from a respective end of the rotor.

12. A rotary dynamoelectric machine as claimed in claim 11, in use of which coolant fluid is circulated into one end of the rotor, through the rotor near to the surface and out of the other end of the rotor.

13. An electric motor as claimed in any preceding claim.

14. A DC electric motor as claimed in claim 13.

15. A rotary dynomoelectric machine substantially as hereinbefore described with reference to and as illustrated in Figures 1 to 3 ofthe accompanying drawings.