US2787721A

US2787721A - Dynamoelectric machines

Info

Publication number: US2787721A
Application number: US473587A
Authority: US
Inventors: Tudge Joseph
Original assignee: Metropolitan Vickers Electrical Co Ltd
Current assignee: Metropolitan Vickers Electrical Co Ltd
Priority date: 1954-01-19
Filing date: 1954-12-07
Publication date: 1957-04-02
Anticipated expiration: 1974-04-02
Also published as: BE534929A

Description

April 2, 1957 J. TUDGE DYNAMO ELECTRIC MACHINES 2 Sheets-Sheet 1 Filed Dec. 7, 1954 I .N'VENTOR ATTORNEYS A ril 2, 1957 Filed Dec. 7, 1954 J. TUDGE DYNAMO ELECTRIC MACHINES {/9 FIG. 2.

2 Sheets-Sheet 2 \NVENTOR M ATTORNEYS United States Patent DYNAMOELECTRIC MACHINES Joseph Tudge, Walkden, England, assignor to Metropolitan-Vickers Electrical Company Limited, London, England, a British company i Application December 7, 1954, Serial No. 473,587

Claims priority, application Great Britain January 19, 1954 3 Claims. (Cl. 310-61) This invention relates to dynamo-electric machines and has an important application in large size turbo-alternators.

It is well known that one of the main factors limiting the output of a large dynamo-electric machine, such as a turbo-alternator, is the rise in temperature. This in turn depends upon heat dissipation, the limiting temperature rise being of course the temperature rise of any individual part or component.

It is customary to cool machines by promoting a flow of gas, such as air or hydrogen, over the surfaces of the core of the conductors.

The present invention is concerned with improving the cooling of the rotor conductors.

. According to the present invention the rotor conductors are formed with longitudinal passages, axially extending inlet ports to said passages formed in the exposed end turns, together with axially extending subslots in the core extending beneath the winding slots and arranged to be fed with cooling gas at each end of the core, radially extending ports between the sub-slots and the conductor passages within the winding slots and discharge ports between the conductor passages in the winding slots and the rotor periphery.

With such an arrangement the coil ends and the embedded portions of the coils are separately and independently ventilated.

Preferably the conductor passages are blocked at or near the ends of the core so that the conductor passages along the mid-part of the core are supplied with gas wholly from the sub-slots.

The radial ports in the embedded parts of the coils may be graded to give a desired distribution of gas flow.

The individual conductors may conveniently each be formed of a pair of superimposed straps, which are channelled or grooved along their contacting faces, so that when placed together they form an internal duct.

In order that the invention may be more clearly understood reference will now be made to the accompanying drawing, in which:

Fig. 1 is a pictorial representation illustrating somewhat diagrammatically the underlying idea of the invention, and

Figs. 2, 3 and 4 are enlarged cross-sectional views of a coil taken on the lines IIlI, IIIIII, and IVIV, respectively.

In the drawing the reference 1 indicates the rotor core of a turboalternator. 2 are wedges closing the slot openings at the rotor periphery. In the drawing there are shown two of the slots between which is a core tooth 3. Extending through each slot is a coil 4, each coil comprising a number of superimposed conductors separated by insulation. In the arrangement shown each conductor comprises an upper strap 5, superimposed on a lower strap 6, the upper straps 5 are grooved along their under surfaces, whilst the lower straps 6 have corresponding grooves in their upper surfaces so that when the two straps are laid together, one over the other, the grooves will register and form longitudinal passages 7. These passages extend throughout the conductors.

It will be appreciated that in cooling conductors internally there are two main factors to consider. There is first the problem of cooling the exposed end turns, such as the end turn 8 shown in the drawing, and there is also the problem of cooling those parts of the conductors which extend through the slots in the core.

In accordance with the invention the external surfaces of the end turns are cooled in the normal manner by air flow over these surfaces whilst the interiors of the conductors are additionally cooled by cooling gas entering through axially extending ports 9 on the side faces of the coils, whilst those parts of the conductors which are located in the core slots are supplied with cooling gas through radial passages 10, fed from sub-slots 11. Thus the gas will enter through the ports 9 and then pass along the longitudinal passages 7 into the core slots, whence it will discharge through the two end radial ports 12, which extend radially outwards to the periphery of the rotor through the wedges 2. Stops 13 extend across the longitudinal passages beyond the radial discharge ports 12, and so prevent the cooling gas from the end turns passing further along the slots.

In this manner the ventilation of the embedded parts of the coil is entirely independent of that of the coil ends and different suctions may be employed.

As above mentioned, the conductors within the slots, i. e., to the right of the stops 13, are fed with cooling gas through a sub-slot 11, which extends axially below each of the winding slots. Cooling gas enters at each end 14 of a sub-slot and from the sub-slot passes radially outwards, i. e. upwards in the drawing, through the radial ports it), which extend upwardly as far as the uppermost conductor passage, but do not extend as far as the periphery. The ports 10 are uniformly spaced along the rotor and between each pair of ports 10 is a discharge port 15, which extends to the periphery of the rotor in a similar manner to the ports 12 at the end of the rotor. Thus, cooling gas from the sub-slots 11 passes up the ports 10, then along the conductor passages and finally discharges through the ports 15.

It will be appreciated that with such an arrangement all parts of the rotor winding are subjected to cooling, and the possibility of hot spots is substantially avoided.

If desired the ports 10 and also the ports 15 may be graded to give a desired distribution of gas flow.

Whilst, in the actual arrangement shown, the gas from the end turns discharges through the two ports 12 in the slots, clearly more than two ports may be so employed if desired or even a single port.

The stops 13 may conveniently corn-prise insulating blocks extending across the passageway or, alternatively, they may be of conducting material and may, for example, be formed of the actual material of the conductors, by omitting a short length of channelling.

Whilst in the actual arrangement shown the longitudinal passages are formed internally of the conductors, clearly other arrangements could be employed, for instance, longitudinal channels could be formed in the external face or faces of the conductors and could be closed by insulation over the top of the channel.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A dynamo-electric machine having a stator and a rotor having a core provided with winding slots, a winding having portions embedded in slots in the rotor core and exposed end turns and comprising conductors having longitudinal passages form-ed therein, means formed in the exposed end turns of the winding and defining axially extending inlet ports leading to said longitudinal conductor passages, means defining radially extending outlet ports situated within and close to the ends of the rotor core and providing discharge means for said conductor passages in the end turns of the winding to the rotor periphery, walls defining axially extending sub-slots in the rotor core beneath the winding slots therein, means for feeding cooling gas to said sub-slots at each end of the rotor core, means defining radially extending ports between said subslots and said longitudinal conductor passages, and means defining ports between the conductor passages in the embedded portions of the winding and the rotor periphery.

2. A dynamo-electric machine having a stator and a rotor having a core provided with winding slots, a winding having portions embedded in slots in the rotor core and exposed end turns and comprising conductors having longitudinal passages formed therein, a cooling circuit for the exposed end turns of the winding including means defining axially extending inlet ports to said conductor passages in the exposed end turns of the winding, and means defining radially extending outlet ports situated within and close to the ends of the rotor core and discharging to the rotor periphery, a cooling circuit for the embedded portions of the winding comprising walls defining axially extending sub-slots in the rotor core beneath the winding slots therein, means for feeding said sub-slots with cooling gas at each end of the rotor core, means defining radially extending ports between said subslots and said longitudinal conductor passages, means defining discharge ports between the conductor passages in the embedded portions of the winding and the rotor periphery, and blocks in said longitudinal conductor passages separating said cooling circuit for the embedded portions of the winding from said cooling circuit for the exposed end turns of the winding.

3. A dynamo-electric machine having a stator and a rotor having a slotted core, a winding having portions embedded in slots in the rotor core and exposed end turns and comprising conductors having longitudinal passages formed therein, a cooling circuit for the exposed end turns of the winding including means defining axially extending inlet ports to said conductor passages formed in the exposed end turns and means defining radially extending outlet ports situated within and close to the ends of the rotor core and discharging to the rotor periphery, together with a cooling circuit for the embedded portions of said winding comprising walls defining axially extending subslots in the rotor core beneath the winding slots, means for feeding said sub-slots with cooling gas at each end of the rotor core, means defining radially extending ports between said sub-slots and said longitudinal conductor passages, said radially extending ports being graded in cross-section to give a desired distribution in gas flow, means defining discharge ports between the longitudinal conductor passages and the rotor periphery, and blocks in said conductor passages and separating said cooling circuit for the embedded portions of the winding from said cooling circuit for the exposed end turns thereof.

References Cited in the file of this patent UNITED STATES PATENTS 2,653,255 Baudry Sept. 22, 1953 2,664,512 Huntley Dec. 29, 1953 FOREIGN PATENTS 714,319 France Sept. 1, 1931