US1522333A - Cooling of dynamo-electric machines - Google Patents

Description

Jan. 6, 1925. 1,522,333

G. SCHROEDER COOLING OF DYNAMO ELECTRIC MACHINES Filed Oct.- 30, 1920 2 Sheets-Sheet 1 2 Sheets-Sheet 2 G. SCHROEDER Filed Oct. 30. 1920 COOLING OF DYNAMO ELECTRIC MACHINES lJan. 6, 1925.

Patented Jan. 6, 1925e PATENT OFFICE.

GIULIO SCERCEDER, OI ENGLAND.

COOLING OF DYNAwO-ELECTRIG MACHINES.

Application tiled, october S30, i920.

To all whom t may] concern:

Be it known that I, GIULIO Sormornnr., a subject of the King of Italy, residing in Hale, Cheshire, England, have invented certain new and useful Improvements in the Cooling of Dynamo-Electric Machines, of which the following is a specilication.

This invention relates to the cooling arrangements of turbo 'alternators and other high speed electric machinery.

In machines of the kind to which this invention relates the limitations to the possibility of the cooling of the rotor greatly influence the output that can be obtained from a given size of machine. rl`his is due to the greater difliculty of supplying cooling fluid in suflicient quantities to the rotor than to the stator, and to the difficulty in applying the cooling fluid near those parts of the rotor where the heat is generated7 principally owing to the mechanical requirem ents of the structure.

In accordance with this invention the cooling arrangements are divided into two concentric systems and the gaseous cooling fluids supplied to the two systems are different in that the fluid for the inner system has a materially greater heat absorbing capacity per unit volume within the temperature limits permissible in the machine than the fluid supplied to the outer system. In general air will be the fluid employed and the heat absorbing capacity of the supply to the inner system will be increased by passing that air through a refrigerating plant so that its temperature at admission to the machine is reduced below the temperature of the surrounding atmosphere, After leaving the inner system the air or other gaseous fluid may be either discharged outside or circulated or passed into tie outer cooling system.

rI`he inner system will deal with the interior of the rotor and the intensified cooling which it provides will give the result that the rotor temperature need no longer be a limitation to the output of large high speed machines.

The invention will be further described by the aid of the accompanying drawings in which Figure l shows in vertical section a Serial No. 420,667.

machine to which the invention is applied; Figure 2 shows a transverse section through the rotor shown in Figure l; Figure 3 shows an inside elevation of the member in which the air inlet and outlet passages for the machine are formed; Figure 4l shows a section on the line IV-IV of Figure 3; Figure 5 shows in vertical section a machine similar to that shown in Figure 1 but embodying a modification at the outlet end of the rotor; Figure 6 shows in elevation an arrangement of apparatus for producing the cooling and compressing of the cooling fluid for the r0- tor.

In the form shown in Figures l-4 the cooling gaseous fluid for the rotor flows in a closed circuit through the rotor and through a refrigerator as indicated by the arrows so as to avoid the continual drawing in of large quantities of fresh fluid which may bring with them a considerable amount of dust which may accumulate in the rotor passages. In this circulation the air passes through a refrigerating chamber A in which it flows over cooling coils which may be arranged in two sets, to the first of which water at approximately atmospheric temperature from any convenient cold supply is delivered while in the second brine or other suitable liquid from a refrigerator flows. rEhe connections for the water supply are indicated at B and those for the` refrigerating liquid are shown at C. A centrifugal blower or compressor D takes the air as it comes from the chamber A and drives itforward through the duct E to the inlet end of the rotor, making connection with the admission chamber F. This chamber leads the air to the inlet end of axial passages through the rotor and from the other end of these passages the air passes into the outlet chamber G similar in form to the chamber F. To this chamber is attached a duct I-I which completes the circuit back to the chamber A.

In arranging the circulation of the fluid through the rotor the axial passages will preferably be so located as to produce an approximation to uniformity of temperature of the teeth and of the metal adjacent to the roots of the teeth. In the arrangey ment illustrated the axial passages are shown at .l as formed by continuations ot the slots so that the air flows directly in contact with the coils and with the metal at the roots oi the teeth.

As shown in Figures le and ti, the member in which the admission chamber F tor the rotor air is formed also provides in the usual way a passage for conducting air to the stator cooling system. This passage is lrept quite distinct from the chamber F but surrounds it on both sides so that the two streams oil cooling tluid tor rotor and stator respectively pass upward into the machine side by side but are kept apart. In the arrangement shown in Figure l the construction of this member is the same at each end of the machine, the only difference being that at the outlet end the rotor air is owing down and the stator air is flowing upward, the stator cooling system being ot a. type in which the air enters at both ends and flows axially and then radially, leaving by an out let at the top ot' the machine as indicated by the arrows.

It is to be noted that where the air passes from a stationary to a rotating part. and vice versa, a lioint is made having small clearance or rubbing contact so as to minimize leakage from the rotor coolingsystemeither to the stator cooling' srstcru or lo the external air. 'llo take care oit small un avoidable leakage an inlet in: be provided on the suction side of the s v n rontroliefl by a non-return valve .l wliieh iieriuitfa ihh iniow of makeup air when the pressure falls below a determined value.

In many cases it will be preterable to pro fide that the coolingy tluid be sont through the rotor under a pressure considerably above atmospheric so as to obtain an increased heat transn'iitting capacit)v for a given area ot rotor duet surface.

Figure 5 illustrates an alternative ar rangement; in which a closed circulation system tor the rotor air not used. ln it the air coming from the outlet end o t the rotor 'Hows indicated by the arrows to join the incoming' air at that end ot the stator and passes with it into the stator cooling system leaving` that system by the outlet shown at the top ot the ligure. lith suoli a construction it is unnecessary to provide an outlet chamber such an indicated at Gr in Figure l, and accordiuglyY the stator air inlet is ot an ordinary construction at this end, that is to say, it has the torni shown in Figures Il and 13, except tor the omission ot the wall separating the part F trom the rest o't the space enclosed by the cover. As the duet Hot Figure Yl is on'iitted in Figure it will he obviousl that the refrigerator inlet (H oit' Figure til will i ceive air from the atmosphere.

By the terni refrigeration used herein,

it is intended to indicate the lowering of the temperature of the gaseous Huid to a point materially below the temperature ot' the surrounding atniospherc.

lt will be understood that the illustrations given are only by way ot example and. that the relative arrangement and proportions of the plant shown in the figures are only diagrammatic.

that I claim as my invention and desire to secure by Letters Patent is:

l. The combination ot a dynamo electric machine having Ventilating passages ar ranged in the machine structure to torm two concentric systems, the outer system serving lor the exterior ot' the rotor and for the stator and the inner system tor the interior ol" the rotor and con'iprising ducts in the rotor body and an inlet chamber toi-ming part ot the stationary structure of the machine adjiacent one end otthe rotor, the, said chamber enclosingl the inlet ends ot' the ducts and separating them trom the outer system, and means for supplying the two systems with gaseous fluid at ditlerent telnperatures, the colder fluid being ted to the inner system.

2. The combination of a dynamo electric machine having Ventilating passages arranged in its structure to 'form inner and outer concentric systems. the inner system serving tor the interior ot the rotor and the outer system 'tor the exterior ot the rotor and tor the stator and each system comprisv ing an inlet chamber formed in one and the same .stationary end part ot the inachine structure, the inlet chamber for the inner system lying` inside that tor the outer :"ivstem` and means tor supplying the two systems with gaseous fiuids (littering in teuiperature, the colder tluid being ted into the inner inlet chamber.

3. The combination of a dynamo-electric machine having ii'entilating passages arU ranged in the machine structure to torni two concentric systems. the outer system serving for the exterior ot thc rotor and tor the stator and the inner system for the interior of the rotor and comprising ducts in the rotor body and an inlet chamber Atorming 5 part ot the stationary structure ot the luachine adjacent one end of the rotor. the said chamber enclosing the inlet ends ot'A the ducts and separating them trom the outer system. means tor supplying the two systems 130 with separate bodies ot gaseous tluid` and means tor rirfrigerating one ot such bodies so that the fluid 'ted to the inner svsten'l is colder than that iled to the outer s stem or than the adjacent atmosphere.

4. The conibination ot a (.l \uiamo-elertrie machine having ventilating passages :ir ranged in its structure to form inner and outer concentric systems, the outer system having an inlet chamber at each end of the u machine, and the inner system having an inlet Chamber at one end of the machine, nieans 'for leading the discharge from the inner system into an inlet chamber for the outer system, means for supplying to the two systems 'from two external sources separate bodies of gaseous cooling uid, and

means for refrigeratng one of said bodies so that the fluid fed to the inner system is colder than that fed to the outer system or 10 than the adjacent atmosphere.

In testimonyv whereof I afix iny signature.

GIULIO SCHROEDER.

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