US4876470A — Gas-cooled electric machine

Claim 1

Independent Claim 349 words

An electric machine comprising: a housing, a rotor, and a stator having a laminated body disposed in said housing, said stator having indirectly cooled stator winding conductors disposed in grooves on an inside circumference of said stator; the laminated body of said stator comprising stacks of laminations grouped in packages of laminations separated at intervals to define radial ducts; the radical ducts forming radially extending cooling slits, said cooling slits connecting annular air-gap cavities located at the inside circumference of said laminated stator body to chambers which are situated between an outside circumference of the laminated stator body and the housing; said chambers comprising cold-gas chambers from which cold cooling gas is forced into associated first air gap cavitites of said laminated stator body and hot gas chambers into which heated cooling gas flows from second air gap cavities of said laminated stator body in a radially outward direction, one of said hot gas chambers being located at one end of said machine, another of said hot gas chambers being located at a central section of said machine; cooling means which supply the cooling gas being located at least at one end of said machine, said cooling means supplying cooling gas as cold gas to the cold-gas chambers and extracting heated cooling gas from the hot gas chambers, said supply of cooling gas being cooled by at least one of said cooling means; wherein cooling gas lines connect said hot-gas chambers to said cooling means, said hot-gas chamber located at the central section of the machine having at least one separate cooling gas line which circumvents said hot-gas chamber located at one end of the machine and said cold gas chambers and establishes a direct connection between said hot-gas chamber located at the central section of the machine and the cooler, each of said cold gas chambers being connected by additional cooling gas lines to a discharge area of one of said cooling means located at one end of said machine, said additional cooling gas lines passing through said warm gas chamber located at one end of the machine.

Claim 2

Dependent Claim 349 words

An electric machine comprising: a housing, a rotor, and a stator having a laminated body disposed in said housing, said stator having indirectly cooled stator winding conductors disposed in grooves on an inside circumference of said stator; the laminated body of said stator comprising stacks of laminations grouped in packages of laminations separated at intervals to define radial ducts; the radical ducts forming radially extending cooling slits, said cooling slits connecting annular air-gap cavities located at the inside circumference of said laminated stator body to chambers which are situated between an outside circumference of the laminated stator body and the housing; said chambers comprising cold-gas chambers from which cold cooling gas is forced into associated first air gap cavitites of said laminated stator body and hot gas chambers into which heated cooling gas flows from second air gap cavities of said laminated stator body in a radially outward direction, one of said hot gas chambers being located at one end of said machine, another of said hot gas chambers being located at a central section of said machine; cooling means which supply the cooling gas being located at least at one end of said machine, said cooling means supplying cooling gas as cold gas to the cold-gas chambers and extracting heated cooling gas from the hot gas chambers, said supply of cooling gas being cooled by at least one of said cooling means; wherein cooling gas lines connect said hot-gas chambers to said cooling means, said hot-gas chamber located at the central section of the machine having at least one separate cooling gas line which circumvents said hot-gas chamber located at one end of the machine and said cold gas chambers and establishes a direct connection between said hot-gas chamber located at the central section of the machine and the cooler, each of said cold gas chambers being connected by additional cooling gas lines to a discharge area of one of said cooling means located at one end of said machine, said additional cooling gas lines passing through said warm gas chamber located at one end of the machine.

Claim 3

Dependent Claim 47 words

Electric machine as claimed in claim 1, wherein the hot-gas and cold-gas chambers are formed by radially extending partitions which are disposed in a cavity between the outside circumference of the laminated stator body and the housing, the cooling-gas lines being formed by tubes of various length.

Claim 4

Dependent Claim 113 words

Electric machine as claimed in claim 2, wherein the partitions separate said hot-gas chamber located at one end of the machine, one of said cold-gas chambers adjacent thereto and said hot-gas chamber located at the central section of the machine, cooling gas being fed to the hot-gas chamber located at one end of the machine through the cooling slits from the air gap of the machine radially outwards, and being fed from said one of said cold-gas chambers through the cooling slits radially inwards to the air gap of the machine and after deflection through said cooling slits radially outwards again into the hot-gas chamber located at the central section of the machine.

Claim 5

Dependent Claim 62 words

Electric machine as claimed in claim 3, wherein said cooling means comprises impelling means and with a specified impellant power of said impelling means, a volumetric flow through the hot-gas chamber located at the central section of the machine is adjusted by dimensioning the tubes so that their cross-section is more than 50% of a volumetric flow impelled by said impelling means.

Claim 6

Dependent Claim 68 words

Electric machine as claimed in one of claims 1, 2, 3 or 4, wherein the distribution of the volumetric flow produced by said impelling means can be set by varying an axial width of the cooling slits in a manner such that the slit width in a section of the laminated stator body at the end is less than in a central section of the laminated stator body.

Claim 7

Dependent Claim 97 words

Electric machine as claimed in claim 5, wherein the distribution of the volumetric flow produced by said impelling means can be set by a variable axial width of the laminated subassemblies of the laminated stator body and by a variable axial width of the cooling slits in a manner such that the width of the laminated subassemblies in the section at the end is less than in the central section of the laminated stator body and their mutual spacing in the section at the end is less than in the central section of the laminated stator body.

Claim 8

Dependent Claim 43 words

Electric machine as claimed in claim 7, wherein at least two of said cooling gas lines which connect the hot-gas chambers to the cooling means have different cross-sections to promote an increased gas flow to the cooling gas line having a larger cross-section.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1992-10-23	1993-04-24	1993-10-24	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1996-10-23	1997-04-24	1997-10-24	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2000-10-23	2001-04-24	2001-10-24	$7700.00	Window Closed / Lapsed

Gas-cooled electric machine

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