US2707242A

US2707242A - Inner-cooled generators with vertical coolers

Info

Publication number: US2707242A
Application number: US389349A
Authority: US
Inventors: Rene A Baudry
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1953-10-30
Filing date: 1953-10-30
Publication date: 1955-04-26
Anticipated expiration: 1972-04-26
Also published as: GB753114A; DE1033322B; JPS326460B1; FR1113911A; CH324043A

Description

April 26, 1955 R. A. BAUDRY 2,707,242

INNER-COOLED GENERATORS WITH VERTICAL COOLERS Filed Oct. so, 1953 2 Sheets-Sheet l INVENTOR Rene A. Baudry ATTORNEY April 26, 1955 R. A. BAUDRY INNER-COOLED GENERATORS WITH VERTICAL COOLERS 2 Sheets-Sheet 2 Filed. Oct.

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United States Patent INNER-COOLED GENERATORS WITH VERTICAL COOLERS Ren A. Baudry, Pittsburgh, Pa., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application October 30, 1953, Serial No. 389,349

19 Claims. (Cl. 310-57) My present invention relates to improvements in intier-cooled hydrogen-cooled turbine-generators, or other similar dynamoelectric machines, in which the heat generated in the stator and rotor conductors is directly removed through cooling-ducts which are in good thermal relation to the conductors. The present invention is an improvement which is particularly useful in, and in fact was made possible or practicable by, a single-direction ventilation-system which is described and claimed in the copending application of Paul R. Heller and myself, Serial No. 394,602, filed November 27, 1953. In this single-direction ventilation-system, the air gap of the machine is sufiiciently large to act as a hot-gas collectingchamber and as an axial duct for a substantial portion of the ventilating-gas of the machine. In my present invention, this feature is combined with other improvements to provide a very compact and efficient coolingsystem.

My present invention relates to a special vertical-cooler arrangement in such a single-direction ventilation-system. This vertical-cooler invention is characterized by the use of a pair of vertical coolers, disposed so as to receive the hot gas which is exhausted from the air gap by a blower at at least one end of the machine. This pair of vertical coolers is located axially between the stator Winding and the frame-bracket, and said coolers are located radially between the bearing-housing and the outer frame-shell. This placement of the vertical coolers avoids the introduction of unduly heavy bulbous frame-structures, which have heretofore been used with vertical coolers, and which have required rather complicated internal baflling, and have increased the outer frame-dimensions of the machine, besides being quite impracticable for withstanding the higher gas-pressures which are even now being used for hydrogen-cooled inner-cooled generators, with still higher gas-pressures in prospect.

Vertical coolers are of necessity shorter than horizontal coolers which are disposed between the outer periphery of the stator-core and the outer frame-housing; and hence it has not often been practicable, heretofore, to use vertical coolers, notwithstanding their many practical advantages. In the single-direction ventilation-system in which my present vertical coolers are used, the reduced cooler-length, and hence the reduced cooler-volume, which are entailed by the vertical disposition of the coolers, are made possible by the use of the air gap as a hotgas chamber exclusively, the increased gas-pressures, the increased fan-pressures, the resulting reduced quantity of cool gas which has to be moved, and the adoption of the latest designs of compact finned-tube arrangements. These features have all contributed to a reduction in the working-volume of the coolers, so that vertical coolerarrangements are now possible.

Among the many advantages of my vertical-cooler embodiment of the single-direction ventilation-system, I would emphasize the very important advantage that no hot gas now comes into contact with the frame, this eliminating the frame-distortion problem. This is because all of the hot gas of the machine is collected in the air gap and at one end of the stator-windings, and this hot gas is evacuated, in an axial direction, by a multistage blower, and then divided into two streams, one of which flows through each of the two vertical coolers at that end of the machine. Thus, it is only the cooled gas which comes into contact with the outer cylindrical frame-housing.

In the accompanying drawing, I have shown two illustrative alternative forms of embodiment of my invention. Figure l is a side-elevational view, the top half being in longitudinal section, showing a hydrogen-cooled turbine-generator embodying my invention in a form in which I use only a single pair of vertical coolers, disposed at only one end of the machine, and suitable for all except perhaps the very highest ratings of future machines which are larger than any machines thus far sold;

Figs. 2, 3, 4 and 5 are successive transverse sections on the section-planes indicated, in Fig. l, by the lines IIII, III-III, IV-IV and VV, respectively;

Fig. 6 is a partial horizontal sectional view, on the section-plane indicated at VI-VI in Fig. l; and

Figs. 7 and 8 are respectively vertical and horizontal longitudinal sections of an alternative machine-design in which the vertical coolers must be used at both ends of the machine, in order to meet the required ratings.

Fig. 1 shows a turbine generator, which is illustrative of a dynamoelectric machine having a stator member 15 and a rotor member 16, separated by an air gap 17.

The stator member 15 includes a substantially gastight machine-enclosing housing, which comprises an outer cylindrical frame-shell or core-surrounding housing-portion 18, and two

brackets

19 and 20, enclosing the respective ends of the outer frame-shell. The housing is filled with a gaseous filling, which is preferably hydrogen, at a gas-pressure which is adapted, at times, to be at least as high as 30 pounds per square inch, gauge, which may be regarded as a minimum pressure, as some what higher gas-pressure are contemplated. While hydrogen is preferred, it is possible to use other gases having a molecular weight lower than nitrogen, the low molecular weight being desirable in order to keep down the windage-losses resulting from the rotation of the rotor member 16 within the gas.

The stator member 15 also comprises a cylindrical stator-core 21, having a plurality of winding-receiving stator-slots 22 (Fig. 5). The stator member also comprises an inner-cooled stator winding 23 having coil-sides lying within the winding-receiving slots 22, and coil-ends lying beyond the respective ends of the stator-core 21. This stator winding 23 is an inner-cooled winding, having cooling-ducts 24 which are in good thermal relation to the stator-conductors, for substantially directly cooling said stator-conductors. The stator-winding cooling-ducts 24 have inlet-openings 24a at one end of the winding, and outlet-openings 24b at the other end.

A recirculating stator-winding cooling-system is necessarily provided, for recirculating a stator-winding coolingfiuid in said inner-cooling stator-winding ducts 24, said recirculating cooling-system including a means for cooling the stator-winding cooling-fluid. Although it is not necessary to use the gas which fills the machine-housing as the stator-winding cooling-fluid, I prefer to do so, in which case, the duct-inlets 24:: are open to an end-space 24 within the machine, at one end of the machine, while the duct-outlets 24b are open to another end-space 24" within the machine at the other end of the machine, thus cooling the stator winding 23 with the gas which is enclosed within the machine-housing, said gas being cooled by the subsequently described coolers. The stator winding 23 is usually a polyphase winding, and in the large machinesizes to which my present invention is particularly applicable, the stator winding 23 is provided with ground insulation 25 (Fig. 5) which is good for 10,000 volts, or higher.

The stator-core 21 is also provided with a plurality of core-ventilating stator-ducts, which may be eit ier radially disposed ducts or spaces 26, as shown in Figs. 1 to 8, or other suitable stator-core ventilating-ducts may be used.

The rotor member 16 has a cylindrical rotor core 28, which has a plurality of axially extending winding-receiving slots 29, and an inner-cooled rotor winding 30 having cooling-ducts 31 in good thermal relation to the rotorconductors for substantially directly cooling said rotorconductors. Preferably, or in practically every case in which my invention would be used, the rotor-winding cooling-ducts 31 have inlet-openings or means, 32, at

the respective ends of the rotor winding, and outlet-openings 33 at a plurality of intermediate discharge-points within the winding-receiving rotor-slots, these dischargepoints being commonly grouped together near the center of the rotor-core, and being connected to the air gap 17 by a plurality of radially extending rotor ducts or holes 34 which discharge the rotor-cooling gas to the rotorperiphery. The rotor windings 30 are insulated for a voltage which is considerably lower than the stator windings 23, so as to require a much thinner rotor-insulation, which is too thin to be shown on the scale to which my drawings are drawn.

The rotor core 28 is carried by a rotor shaft 35, which is supported by a pair of bearing housings 36 near the respective frame-

brackets

19 and 20. Associated with the bearing-housings 36, are suitable gland-seal members 37 for maintaining gas-tight joints around the respective shaft-ends. One end of the shaft is connected to a coupling 38, whereby the machine may be connected to a turbine or other prime mover; while the other end of the shaft carries two slip rings 39 for exciting the rotor winding 30, which serves as the field-winding for the machine.

The air gap 17 has a single gaplength of the order of from three and one half to five inches, more or less, so that the air gap is sufiiciently large to act as a hot-gas collecting chamber and as an axial duct for a substantial portion of the ventilating-gas of the machine, as will be evident from the subsequent explanations.

It is necessary to provide a gas-moving means, for maintaining a circulation of the gas within the machineenclosing housing 18 19-20. In the form of embodiment of my invention which is shown in Figs. 1 to 6. this gas-moving means comprises a single evacuating blower 41, carried by the rotor member at one end of the rotor core, and directed so as to evacuate hot gas from that end of the air gap 17, and also from the stator endspace 24" in which the stator-winding duct-outlets 24h discharge. The blower 41 includes a supporting-means of such nature that it provides one or more axially extending under-blower passages 42, extending axially underneath the blower 41. The blower 41 is preferably a multistage blower, which is capable of developing a considerable blower-pressure for rapidly moving the hot gases in an axial direction.

It is necessary to provide a heat-exchanging means. which is disposed within the machine-housing 1819 20, for cooling the circulated gas. In accordance with my invention, this heat-exchanging means comprises vertically disposed coolers. Figs. 1 to 6, the heat-exchanging means comprises a pair of vertical coolers 44 and 45. These coolers are located axially between the stator-winding duct-outlets 24b and the housing bracket 20 at that end of the machine, as

shown in Fig. 1. The blower 41 is disposed underneath,

or within the axial confines of, the stator-winding endturns which have the duct-outlets 2417, so that the blower 41 discharges the hot gas axially toward the portion of the housing which is occupied by the pair of coolers 44 and 45. The two vertical coolers 44 and 45 are located radially between the bearing housing 36 and the outer frame-shell 18, as shown in Fig. 6, so that the hot gas which is discharged axially from the blower 41 divides into two streams, one stream flowing to the right. through the vertical cooler 44, while the other stream flows to the left, through the vertical cooler 45, as shown in the horizontal sectional view, which is Fig. 6.

Each of the coolers 44 and 45 comprise a plurality of substantially straight, vertical, liquid-cooled, finned pipes, each end of each cooler terminating in a cooler-head 47. The outer frame-shell 18 is provided with cooler-accommodating perforations 48, having pressure-resistant reinforcing means 51, which are secured to the frame-shell around each perforation 48. The top and bottom coolerheads 47 of each cooler 44 and 45 are hermetically but removably secured to their own reinforcing-means 51; so that each cooler can be lifted vertically out of the machine, after disconnecting its two cooler-heads 47. The waterconnections, for circulating water or other coolant through the cooler-pipes, are preferably provided at the lower cooler-head 47, as shown in Figs. 2 and 3.

I provide suitable hot-gas guiding-means, for guiding the hot gases to and through the blower 41 and the coolers 44 and 45. Thus, the end-winding space 24" into which the stator-winding duct-outlets 24b discharge In the form of my invention shown in t is confined by an outer cylindrical or arcuate partition 53, a fiat transverse plate or disc 54 which extends vertically between the two coolers 44 and 45 on the sides thereof closest to the stator end-windings, and the shroud 55 of the blower 41. The transverse plate or disc 54 is provided with a central hole 54a which is more or less hermentically joined to the outer periphery of the blowershroud 55.

Surrounding the inner end of the bearing, in the space between the two vertically disposed coolers 44 and 45, there is a stationary funnel-like duct-member 56, the inner end of which comes into near contact with the rotating end of the blower 41, so that there is little gas-leakage at this point. This keeps the hot discharge-gases from the blower away from the inner end of the bearing, at the point where the discharged hot gases divided into two streams, flowing to the right and the left to enter the coolers 44 and 45, respectively.

Extending vertically between the two coolers 44 and 45, at their sides closest to the housing-bracket 20, there is a curved transverse plate or disc 57, which bulges or is curved, inwardly, toward the disc 54, and away from the housing-bracket 20. This curved transverse plate or disc 57 has a central hole 57a which is substantially hermetically sealed to the large end of the funnel-like member 56, so as to provide a separation between the hot gas which is flowing to the right and left between the two ver tical coolers 44 and 45, and cold gas which flows radially inwardly in the flat end-space 57b between the curved plate 57 and the bracket 20, and then axially inwardly through the funnel-like member 56, into the under-blower passages 42, to ventilate that end of the rotor-windings, as will be subsequently described.

The cold gas, which is delivered from the coolers 44 and 45, is used for the inner-cooling of the rotor winding 30, the inner-cooling of the stator winding 23, and the cooling of the stator-core 21. In the particular construction which is shown in Figs. 1 to 6, these functions are accomplished by a structure on which some of the cold gas is led into both ends of the rotor winding 30, some to the inlets 24a of the stator winding 23, and some to the outer peripheries of the radial cooling-ducts 26 of the stator core. An essential feature of this construction is the provision of an axially extending, peripherally disposed, through duct-means, such as a duct 58 (Fig. l), to provide an axial communication from one end of the machine to the other. In the form of embodiment shown in Fig. 1, the through-duct 58 is illustrated as being in the space between the outer periphery of the stator core 21 and the outer frame-shell 18.

In the construction which is shown in Fig. l, the stator member 15 provided, as is well known, with a plurality of axially spaced frame-rings 61 to 64, extending inwardly from the outer cylindrical frame-shell 18 in the axial length whlch is occupied by the stator core 21. The frame-ring 61 is secured to one end of the cylindrical or arcuate partition 53, which surrounds the hot-gas discharge-end space 24" of the stator-winding ventilation. The space 53a outside of this cylindrical or arcuate partrtion 53 1s filled with cooled gas which is delivered by the two coolers 44 and 45. The through-duct 58 in Fig. 1 extends from this cool-gas space 53a outside of the cylrndrlcal or arcuate partition 53, all the way through the machine, to discharge, beyond the frame-ring 64, in the end-space 24' which feeds said cool gas to the statorwlndlng duct-inlets 24a, and to the rotor-winding inletopenings 32 at that end of the machine.

As shown in the horizontal sectional view, Fig. 6, the cool-gas space 53a which is outside of the cylindrical or arcuate partition 53 is also in communication with the radial space 57b between the curved transverse plate 57 and the housing-bracket 20; and hence some of the cooled gas is supplied to the rotor-winding inlet-openings 32 at this end of the machine.

At the other end of the machine, the cold-gas endspace 24' is nearly altogether, or substantially, closed off from the end of the air gap 17, at that end of the machine, by means of a stationary cylindrical bafile-mernber 69, (Fig. I), which has a small clearance with that end of the rotor member 16, so as to limit, or substantrally stop, the escape of cool gas directly from the endspace 24' into that end of the air gap 17, as described in a patent of Paul R. Heller and myself, No. 2,626,365, granted January 20, 1953.

The through-duct 58 is provided with lateral openings 70 for discharging the cooled gas into the annular spaces 70' between the successive frame-rings 61 to 64, these annular spaces 70' being disposed between the outer periphery of the stator-core 21 and the outer cylindrical frame-shell 18. Since the radial stator-core cooling-spaces 26 are in communication with these annular frame-ring spaces 70', the cooled gas is thus led radially inwardly, through all of these radial cooling-spaces or ducts 26 of the stator core, thereby cooling the stator core, and discharging the heated core-cooling gas into the air gap 17. A suitable resistance to the flow of this core-cooling gas is provided by a proper restriction of the size of the openings 70 in the through-duct 58, so as to properly control the division of the gas-flow, so that each part receives the quantity of gas which is required to cool the same.

The cool-gas space 5311 which is outside of the cylindrical or arcuate partition 53 may contain a fifth framering 71, which is provided with a plurality of openings 72 therethrough, as shown in Fig. 4, so that the entire space outside of this cylindrical or arcuate partition 53 is in effect a single space 53a, all portions of which are in communication with each other.

The operation of the form of embodiment of my invention which is shown in Figs. 1 to 6 may now be summarized. The blower 41 exhausts the hot gases from the air gap 17, and from the stator-Winding outlet-end 24" in the space inside of the cylindrical or arcuate partition 53. The blower delivers this hot gas, in two streams, so that it spreads to the right and to the left and flows laterally through the two vertical coolers 44 and 45, respectively.

The gas which is discharged from the coolers 44 and 45 is cold or cooled gas, which appears in the space 530 outside of the cylindrical or arcuate partition 53. A part of this gas flows into the side edges of the fiat endspace 57b between the curved transverse plate or disc 57 and the housing-bracket 20, and it flows radially inwardly through this space. As shown in the vertical sectional view, Fig. 1, this gas then flows axially through the funnel-like duct or partition 56, so that it passes through the under-blower passages 42 and enters the rotor-winding inlet-openings 32 at that end of the machine.

The remainder of the cool air in the space 530 outside of the cylindrical or arcuate partition 53 leaves that space through the through-duct 58. A part of this through-duct gas is discharged through the duct-openings 70 into the peripheral annular stator-core ventilating-spaces 70 between the successive frame-rings 61 to 64, thence flowing radially inwardly through all of the stator ventilating-spaces 26, and discharging into the air gap 17 which serves as a hot-gas collecting-chamber.

The portion of the cool gas which flows all the Way through the through-duct 58 is discharged into the coolair end-space 24, where most of its divides between the stator-winding duct-inlets 24a and the rotor-winding inlet-openings 32 at that end of the machine. A very small portion of the cool gas in this end-space 24' is admitted to that end of the air gap 17, by means of the baflie 69. In some machines, however, this baffle 69 may block substantially all gas-flow into that end of the air gap.

The inner-cooling gas, for the stator-windings 23 in Fig. 1, enters the inlets 24a from the end-space 24, and it passes all the way through the stator-winding coolingducts 24 from that end of the machine to the other end of the machine, where it is discharged, as hot gas, through the outlets 24b, into the space 24" inside of the cylindrical or arcuate partition 53, where it merges with the hot gas which is being delivered from the air gap 17. This merged hot gas is then picked up by the blower 41, and the recirculating process is continued.

The inner-cooling gas, for the rotor winding 30, in the form of my invention which is shown in Fig. 1, enters the rotor-winding inlet-openings 32 at both ends of the rotor winding 30. A small portion of this rotor-winding cooling-gas may be bypassed directly into the air gap 17, immediately after having cooled the end-winding portions of the rotor winding 30, as shown by the small openings 73 in Fig. 1. The major portion of the rotor-winding cooling gas flows axially through the rotor-winding innercooling ducts 31, from both ends, towards the center of the rotor core 28, at which point the heated gas is discharged to the air gap 17 through the discharge-openings 33 of the inner-cooling ducts 31 and through the radial rotor-ducts 34.

It will be observed that my use of vertically disposed coolers, as shown in Figs. 1 to 6, results in cooling the hot gases before they come into contact with the outer frame-shell 18, as distinguished from earlier systems in which the hot gases came into contact with portions of the outer frame-shell and was then drawn through the cooler before being directed into the cooling-passages of the machine. I thus provide a construction in which the expansion-and-contraction stresses in the outer frameshell and other frame-parts are almost completely avoided. This is a very important consideration in the giant-size machines for which my invention is particularly applicable.

My placement of the vertical coolers, in a place where they do not necessitate extra lateral bulges in the frame, to accommodate the coolers, produces a frame-design which more readily adapts itself for withstanding high gaseous pressures, besides resulting in a very considerable simplification of the internal batfiing which is necessary to route the gases through the cooler, and a reduction in the overall dimensions, which is important in meeting shipping-limitations in the large-size machines to which my invention is particularly applicable.

Other obvious advantages apply to vertical coolers, as distinguished from horizontal coolers, including better appearance, easier cleaning, easier removal and installation of the coolers, much better accessibility to the fans and windings through the cooler-openings, and smaller frame-ring depths which are permitted by the removal of the formerly used horizontal coolers from the framering spaces between the outer periphery of the stator core and the outer frame-shell.

There are many difierent forms of embodiment in which my invention may be applied.

Figs. 7 and 8 show a form of embodiment of the invention, which is useful where coolers must be used at both ends of the machine, either in order to meet the required ratings, either because of cooler-limitations or ventilation-characteristics, or in order to make two different blower-pressures available, one for the inner-cooled

windings

23 and 30, and the other for the stator core 21, as described and claimed in a copending application of Kilgore, Baudry and Heller, Serial No. 394,622, filed November 27, 1953.

In the machine shown in Figs. 7 and 8, the pair of vertical coolers 44, which are located at the machine-end which is bounded by the bracket 20, is duplicated by another pair of vertical coolers 74 at the machineend which is bounded by the bracket 19. This second pair of coolers, 74, may be of the same description as the first pair, 44, except that the second coolers may sometimes be somewhat smaller. The second pair of coolers, 74, use the same kind of bafliing or partition-members as the first pair of coolers, 44, as shown at 54, 55', 56 and 57, these parts corresponding to the correspondingly nltxrmbered unprimed parts at the other end of the mac me.

In Figs. 7 and 8, the air-gap bafile 69 of Figs. 1 to 6 is omitted, and is replaced by a second exhaust-blower 76, which is disposed to exhaust some of the hot gases out of that end of the air gap 17. This second blower 76 develops a much lower blower-pressure than the firstdescribed multistage blower 41. In the illustrative example in Figs. 7 and 8, this second blower 76 is shown as a single-stage blower. Otherwise, the second blower 76 is of the same description as the first blower 41, and it is provided with the same under-blower passages 42. In order to segregate the suction-side of the second blower 76 from the high-pressure cool-gas end space 24 which services the inner-cooled

windings

23 and 30, the rotormember is provided with a cylindrical baflie 77 which is secured to the periphery of the stator core 21 at that end of the machine, and which extends close to the blower-shroud 55' which surrounds the blower 76.

As shown in the horizontal sectional view, Fig. 8, the cool-gas discharge-sides of the second pair of vertical coolers, 74, are partitioned off from the high-pressure cool-gas end-space 24 by transversely disposed vertical barrier-plates 78. As a consequence of the addition of these barrier-plates 78 as shown in Fig. 8, it is necessary to provide a communication-means between the high-pressure cool-gas end-space 24' and the underblower passages 42 at that end of the machine, by a means which is shown in the vertical sectional view, Fig. 7, this means including a plurality of ducts 79 between the plates 54' and 57', so that some of the high-pressure cooled gas is diverted or discharged from the end-space 24' which services the stator-winding duct-inlets 24a, and this high-pressure cooled gas is delivered through the ducts 79 to the flat end-space 57b between the curved transverse plate or disc 57 and the housing-bracket 19, being thence delivered to the large end of the funnel-like member 56', and thence delivered to the under-blower passages 42 under the blower 76, to service that end of the inner-cooled rotor-windings 30.

In the large machine which is shown in Figs. 7 and 8, the stator-frame has six frame-rings 81 to 86, instead of the four frame-rings 61 to 64 of Figs. 1 to 6. These six frame-rings 81 to 86 are axially spaced from each other, within the axial length which is occupied by the stator core 21, the frame-

rings

81 and 86 being more or less hermetically sealed with respect to the respective ends of the stator core. As in Figs. 1 to 6, these six frame-rings 81 to 86 are traversed by a through-duct 88, as shown in Fig. 7. This through-duct 88 carries the high-pressure cool gas, from the space 53a outside of the cylindrical or arcuate partition 53, to the end-space 24' which surrounds the stator-winding duct-inlets 24a.

However, unlike the through-duct 58 of Fig. l, the through-duct 88 of Fig. 7 is imperforate along its sidewalls, so that it does not deliver any gas to the annular spaces 70" between successive frame-rings 81 to 86. These annular spaces 70" between successive frame-rings 81 to 86, as shown in Fig. 8, are in communication with each other, through openings 82 to 85' in the intermediate frame-rings 82 to 85, and the whole group of these annular spaces 70 is placed in communication with the output-sides of the low-pressure coolers 74, by means of ducts 89 (Fig. 8), extending from the barrier-plates 78 to the frame-ring 86.

The operation of the machine which is shown in Figs. 7 and 8 will now be apparent. The hot gas, from the discharge-end space 24" of the stator windings 23, and from the same end of the air gap 17, is compressed to a high blower-pressure by the multistage exhaust-blower 41, and is delivered through the pair of coolers 44 to the high-pressure cool-gas space 53a which is outside of the cylindrical or arcuate partition 53 at that end of the machine. This high-pressure cool-gas space 53:: is in communication with the rotor-winding inlet-openings 32 at that end of the machine, through the inwardly curved portion of the transverse plate or disc 57, as shown in Figs. 7 and 8; this air passing radially inwardly between this curved plate 57 and the housing-bracket 20, to the funnel-like member 56.

The high-pressure cool-gas end-space 5311 which is fed by the discharge-sides of the coolers 44, is placed in communication with the high-pressure cool-gas end-space 24' at the other end of the machine, as shown by the throughduct 88 in Fig. 7. This high-pressure cool-gas end-space 24' encloses the stator-winding duct-inlets 24a, so as to feed gas into these inlets. It is also in communication with the rotor-winding inlet-openings 32 at that end of the machine, through the ducts 79 and the flat end-space 57b between the curved plate 57' and the housingbracket 19. It will be noted that this high-pressure cool gas, for inner-cooling both the stator and

rotor windings

23 and 30, is kept separate from the cool gas which ventilates the stator-core 21.

The stator-core ventilation, in Figs. 7 and 8, is obtained from the single-stage exhaust-blower 76, which draws the necessary quantity of hot gas out of that end of the air gap 17, and compresses it to a much lower blower-pressure than is obtained in the multistage blower 41. This compressed hot gas from the single-stage blower 76 is delivered through the second pair of vertical coolers, 74, and the discharge-sides of these coolers are placed in communication, by the ducts 89 in Fig. 8, with the annular spaces 70 between the successive frame-rings 81 to 86, these annular spaces 70" being in communication with the outer peripheries of all of the radial stator-core ventilating-spaces 26, which discharge their hot gases into the air gap, after cooling the stator core 21. In this way, the necessary low pressure-difierential, which is needed to provide the relatively small amount of stator-core cooling, which is necessary, in obtained from a low-pressure blower 76, thus avoiding the expense of first compressing that quantity of gas to the same high pressuredifferential which is needed for the inner-cooling of the windings, and then throttling it down to the pressure-differential which is needed by the statorsc0re coolingspaces 26.

At the same time, the form of my invention which is shown in Figs. 7 and 8 retains the same vertical-cooler advantages which have been pointed out in connection with Figs. 1 to 6, while providing, also, a convenient means whereby four vertical coolers may be used, instead of just two, in order to obtain more cooler-capacity, to meet the requirements of very large future machines, or to make possible a reduction in the space-requirements of each cooler.

It is to be understood that my invention is not limited to the precise forms of embodiment which have been choosen for the illustration of the principles of the invention; as many changes can be made, in the way of adding refinements, omitting unnecessary features, changes in shape and arrangements, and the substitution of equivalents, without departing from the essential spirit of the invention.

1 claim as my invention:

1. A dynamoelectric machine having a stator member and a rotor member separated by an air gap; (a) said stator member including: a substantially gas-tight machine-enclosing housing, comprising an outer frame-shell and two brackets closing the respective ends of the outer frame-shell; a gaseous filling for said housing; a cylindrical stator core having a plurality of winding-receiving stator-slots; an inner-cooled stator winding, having coilsides lying within the winding-receiving stator-slots and coil-ends lying beyond the respective ends of the stator core, said stator winding having stator-winding coolingducts in good thermal relation to the stator-conductors for substantially directly cooling said stator-conductors; said stator core also having a plurality of core-ventilating stator-ducts; and a means for providing a through duct-means extending axially from one end of the machine to the other; (b) said rotor member having a cylindrical rotor core having a plurality of axially extending winding-receiving rotor-slots; and an innercooled rotor winding having coil-sides lying within the winding-receiving rotor-slots; said rotor winding having rotor-winding cooling-ducts in good thermal relation to the rotor-conductors for substantially directly cooling said rotor-conductors; said rotor-winding cooling-ducts having inlet-openings at the respective ends of the rotor winding and having outlet-openings at a plurality of intermediate discharge-points within the winding-receiving rotor-slots; said rotor windings being insulated for a voltage which is considerably lower than said stator windings; and said rotor core having a plurality of radially extending rotor-ducts extending between the respective outletopenings of the rotor-winding cooling-ducts and the air gap; (6) a pair of bearing-housings for supporting the rotor shaft near the respective brackets of item (a); (d) said air gap being sufiiciently large to act as a hot-gas collecting-chamber and as an axial duct for a substantial portion of the ventilating-gas of the machine; (e) a gas moving means, for maintaining a circulation of the gas within the machine-enclosing housing of item (a), said gas-moving means including an evacuating blower, carried by the rotor member at at least one end of the rotor core of item (b), and directed so as to evacuate hot gas fromthat end of the air gap, said evacuating blower including a supporting-means which provides an axially extending under-blower passage near the rotor-shaft, the inner end of said under-blower passage being in communication with the rotor-winding inlet-openings of item (b) at that end of the machine; (f) heat-exhanging means, for cooling the circulated gas, said heat-exchanging means comprising a pair of vertical coolers located axially between the stator winding of item (a) and the bracket of item (a), at the machine-end at which said evacuating blower (e) is located, said vertical coolers being located radially between the bearing-housing (c) and the outer frame-shell of item (a); each cooler comprising a plurality of substantially straight, vertical, liquid-cooled, finned pipes; each end of each cooler terminating in a cooler-head; said outer frame-shell of item (a) being provided with cooler-accommodating perforations having pressure-resistant reinforcing-means secured to said outer frame-shell around each cooler-accommodating perforation; and means for removably securing each cooler-head hermetically to its own pressure-resistant reinforcing-means; (g) a recirculating rotor-winding and stator-core cooling-system, comprising a gas-circulation guiding-means, including: a hot-gas guiding-means,

for guiding the heated gas of the machine into at least a portion of said gas-moving means (e), and for thence delivering said heated gas first through said heat-exchanging means (f) for cooling said gas, said hot-gas guidingmeans including a means for guiding hot gas from said evacuating blower (e) in two streams flowing through the two vertical coolers (f) at that end of the machine; a first cool-gas guiding-means, for guiding a first portion of the cooled gas from the heat-exchanging means (f) through the inner-cooling ducts of at least the rotor winding of item (12), said first cool-gas guiding-means including a gas-communication means, at one end of the machine, for placing said first portion of the cooled gas in communication with that end of the through duct-means of item (a), and a gas-communication means, at each end of the machine, for placing its end of the through ductmeans in communication with the rotor-winding inletopenings of item (12) at its end of the machine; and a second cool-gas guiding-means, for guiding a second portion of the cooled gas from the heat-exchanging means (f) through the core-ventilating stator-ducts of item (a); and (h) a recirculating stator-winding cooling-system, comprising: a means for recirculating a stator-winding cooling-fluid in said stator-winding coolingducts; and a means for cooling said stator-winding cooling-fiuid.

2. The invention as defined in claim 1, characterized by the gaseous filling of item (a) being a gas having a molecular weight lower than nitrogen, at a gas pressure which is adapted, at times, to be at least as high at 30 pounds per square inch, gauge.

3. The invention as defined in claim 1, characterized as follows: (2) the gas-moving means (e) comprising only a single blower which is present at only one end of the rotor-core, as described in item (e); and (g") the gas-circulation guiding-means (g) including a means for substantially closing the air gap at the other end of the machine.

4. The invention as defined in claim 1, characterized as follows: (e") the gas-moving means (e) also including a second blower, carried by the rotor member at the second end of the rotor core of item (b), said second blower also including a supporting-means which provides an axially extending under-blower passage near the rotorshaft, the inner end of said under-blower passage being in communication with the rotor-winding inlet-openings of item (b) at that end of the machine; (f") the heatexchanging means (f) also including a second pair of vertical coolers, having the same description as the firstmentioned pair (f), except that they are disposed at the second end of the machine; and (g) said hot-gas guiding-means of item (g) also including a means for using the second blower (e") to cause at least a portion of the circulated gas to fiow in two streams through said second pair of coolers (f") to cool said gas.

5. The invention as defined in claim 1, characterized as follows: (a') the core-ventilating stator-ducts of item (a) including a plurality of radially extending coreventilating stator-ducts having their outer ends extending to the outer periphery of the stator-core; and the stator member including a means for providing an axially extending peripherally disposed core-ventilating passage in a space between the outer periphery of the stator core and said outer frame-shell of item (a), and means for placing said passage in communication with the outer peripheral ends of substantially all of the radially extending stator-ducts; and (g') the second cool-gas guiding-means of item (g) including a means for feeding the cooled gas into the peripherally disposed passage of item (a'), and a means for returning hot gas from the inner ends of said radially extending stator-ducts of item (a') to the suction side of at least a portion of said gas-moving means (e).

6. The invention as defined in claim 5, characterized as follows: (e") the gas-moving means (2) comprising only a single blower which is present at only one end of the rotor-core, as described in item (e); and (g) the gas-circulation guiding-means (g) including a means for substantially closing the air gap at the other end of the machine.

7. The invention as defined in claim 5, characterized as follows: (2) the gas-moving means (e) also including a second blower, carried by the rotor member at the second end of the rotor core of item (b), said second blower also including a supporting-means which provides an axially extending under-blower passage near the rotorshaft, the inner end of said under-blower passage being in communication with the rotor-winding inlet-openings of item (b) at that end of the machine; (f") the heatexchanging means (1) also including a second pair of vertical coolers, having the same description as the firstmentioned pair except that they are disposed at the second end of the machine; and (g") said hot-gas guiding-means of item (g) also including a means for using the second blower (e) to cause at least a portion of the circulated gas to flow in two stream through said second pair of coolers .(f') to cool said gas.

8. The invention as defined in claim 1, characterized as follows: (a') the core-ventilating stator-ducts of item (a) including a plurality of radially extending coreventilating stator-ducts extending between the outer periphery of the stator core and the air gap; and the stator member including a means for providing an axially extending peripherally disposed core-ventilating passage in a space between the outer periphery of the stator core and said outer frame-shell of item (a), and a means for placing said passage in communication with the outer peripheral ends of substantially all of the radially extending stator-ducts; and (g') the second cool-gas guidingmeans of item (g) including a means for feeding the cooled gas into the peripherally disposed passage of item (a).

9. The invention as defined in claim 8, characterized as follows: (e) the gas-moving means (e) comprising only a single blower which is present at only one end of the rotor-core, as described in item (e); and (g") the gas-circulation guiding-means (g) including a means for substantially closing the air gap at the other end of the machine.

10. The invention as defined in claim 8, characterized as follows: (e") the gasmoving means (e) also including a second evacuating blower, having the same description as the first-mentioned evacuating blower (2), except that it is disposed at the second end of the rotor core; (f) the heat-exchanging means (f) also including a second pair of vertical coolers, having the same description as the first-mentioned pair (f), except that they are disposed at the second end of the machine; and (g") said hot-gas guiding-means of item (g) also including a means for guiding the hot gas from the second blower (e) in two streams flowing through said second pair of coolers (f") to cool said gas; said first cool gas guiding-means of item (g) drawing its cooled gas from the first pair of coolers (f); and said said second cool-gas guidingmeans of item (g) drawing its cooled gas from the second pair of coolers (f").

11. The invention as defined in claim 1, characterized as follows: (an) the stator-winding cooling-ducts of item (a) having outlet-openings at a first end of the machine, and inlet-openings at the second end of the machine; (gg) the gas-circulation guiding-means (g) also including a third cool-gas guiding-means, using at least a portion of the through duct-means of item (a), for guiding a third portion of the cooled gas from the heat-exchanging means (f) through the inner-cooling ducts of the stator winding of item (a), said third cool-gas guiding-means including a gas-communication means, at the second end of the machine, for placing said third portion of the cooled gas in communication with the stator-winding inlet-openings of item (an) at that end of the machine, and a gascornmunication means for placing the stator-winding outlet-openings of item (an) in communication with the suction side of the evacuating blower (e) at that end of the machine; and (hh) the recirculating statorwinding cooling-system (It) being a part of the gas-circulation guidirw-means (g) and (gg).

12. The invention as defined in claim 11, characterized as follows: (6) the gas-moving means (2) comprising only a single blower which is present at only one end of the rotor-core, as described in item (6); and (g") the gas-circulation guiding-means (g) and (gg) including a means for substantially closing the air gap at the other end of the machine.

13. The invention as defined in claim 11, characterized as follows: (e") the gas-moving means (2) also including a second blower, carried by the rotor member at the second end of the rotor core of item (b), said second blower also including a supporting-means which provides an axially extending under-blower passage near the rotorshaft, the inner end of said under-blower passage being in communication with the rotor-winding inlet-openings of item (b) at that end of the machine; (f") the heat-exchanging means (1) also including a second pair of vertical coolers, having the same description as the first-mentioned pair (1), except that they are disposed at the second end of the machine; and (g") said hot-gas guiding-means of item (g) also including a means for using the second blower (e) to cause at least a portion of the circulated gas to flow in two streams through said second pair of coolers (f") to cool said gas.

14. The invention as defined in claim 11, characterized as follows: (a) the core-ventilating stator-ducts of item (a) including a plurality of radially extending core-ventilating stator-ducts having their outer ends extending to the outer periphery of the stator-core; and the stator member including a means for providing an axially extending peripherally disposed core-ventilating passage in a space between the outer periphery of the stator core and said outer-frameshell of item (a), and means for placing said passage in communication with the outer peripheral ends of substantially all of the radially extending stator-ducts; and (g) the second cool-gas guiding-means of item (g) including a means for feeding the cooled gas into the peripherally disposed passage of item (a), and a means for returning hot gas from the inner ends of said radially extending stator-ducts of item (a') to the suction side of at least a portion of said gas-moving means (e).

15. The invention as defined in claim 14, characterized as follows: (e) the gas-moving means (2) comprising only a single blower which is present at only one end of the rotor-core, as described in item (2); and (g") the gas-circulation guiding-means (g) and (gg) including a means for substantially closing the air gap at the other end of the machine.

16. The invention as defined in claim 14, characterized as follows: (e") the gas-moving means (e) also including a second blower, carried by the rotor member at the second end of the rotor core of item (b), said second blower also including a supporting-means which provides an axially extending under-blower passage near the rotor-shaft, the inner end of said under-blower passage being in communication with the rotor-winding inletopenings of item (b) at that end of the machine; (f") the heat-exchanging means (1) also including a second pair of vertical coolers, having the same description as the first-mentioned pair (1), except that they are disposed at the second end of the machine; and (g) said hot-gas guiding-means of item (g) also including a means for using the second blower (e") to cause at least a portion of the circulated gas to flow in two streams through said second pair of coolers (f") to cool said gas.

17. The invention as defined in claim 11, characterized as follows: (a') the core-ventilating stator-ducts of item (0) including a plurality of radially extending core-ventilating stator-ducts extending between the outer periphery of the stator core and the air gap; and the stator member including a means for providing an axially extending peripherally disposed core-ventilating passage in a space between the outer periphery of the stator core and said outer frame-shell of item (a), and a means for placing said passage in communication with the outer peripheral ends of substantially all of the radially extending stator-ducts; and (g') the second cool-gas guiding-means of item (g) including a means for feeding the ?oo)led gas into the peripherally disposed passage of item 18. The invention as defined in claim 17, characterized as follows: (e") the gas-moving means (e) comprising only a single blower which is present at only one end of the rotor-core, as described in item (e); and (g") the gas-circulation guiding means (g) and (gg) including a means for substantially closing the air gap at the other end of the machine.

19. The invention as defined in claim 17, characterized as follows: (e") the gas-moving means (e) also including a second evacuating blower, having the same description as the first-mentioned evacuating blower (e), except that it is disposed at the second end of the rotor core; (f) the heat-exchanging means (1) also including a second pair of vertical coolers, having the same description as the first-mentioned pair (f), except that they are disposed at the second end of the machine; and (g") said hot-gas guiding-means of item (g) also including a means for guiding the hot gas from the second blower (2") in two streams flowing through said second pair of coolers (f) to cool said gas; said first and third coolgas guiding-means of items (g) and (gg) drawing their cooled gas from the first pair of coolers (f) and said second cool-gas guiding-means of item (g) drawing its cooled gas from the second pair of coolers (f').

Baudry Oct. 8, 1940 Moses Oct. 30, 1951