Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
2001-04-30
2002-10-01
Dougherty, Thomas M. (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C310S156350, C310S156380, C310S266000
Reexamination Certificate
active
06459185
ABSTRACT:
A first subject matter of the invention is an electric machine comprising the following features:
(a) an outer, first stator part and an inner, second stator part, the two stator parts being coaxial and being radially spaced apart by an intermediate space;
(b) each stator part has, facing the intermediate space, a circumferential series of stator poles, at least a partial number of which carries a winding;
(c) a rotor part disposed in the intermediate space;
(d) the rotor part has a circumferential series of alternating permanent magnets and magnetic flux conducting pieces, said permanent magnets being magnetized in circumferential direction;
(e) the width of the permanent magnets—measured in circumferential direction—is larger on the central radius of the rotor part than radially outside and radially inside on the rotor part and the width of the magnetic flux conducting pieces—measured in circumferential direction—is correspondingly smaller on the central radius of the rotor part than radially outside and radially inside on the rotor part;
(f) a first circumferential series of magnetic circuits which—as seen in a plane perpendicular to the rotor axis—each extend through two adjacent stator poles of the first stator part in the plane considered and through two adjacent magnetic flux conducting pieces of the rotor part in the plane considered and through the permanent magnet between the two adjacent magnetic flux conducting pieces in the plane considered, and a second circumferential series of magnetic circuits which—as seen in a plane perpendicular to the rotor axis—each extend through two adjacent stator poles of the second stator part in the plane considered and through two adjacent magnetic flux conducting pieces of the rotor part in the plane considered as well as through the permanent magnet between the two adjacent magnetic flux conducting pieces in the plane considered.
A second subject matter of the invention is an electric machine comprising the following features:
(a) a first stator part and a second stator part, the two stator parts being arranged along a common axis and being axially spaced apart by an intermediate space;
(b) each stator part has, facing the intermediate space, a circumferential series of stator poles, at least a partial number of which carries a winding;
(c) a rotor part disposed in the intermediate space;
(d) the rotor part has a circumferential series of alternating permanent magnets and magnetic flux conducting pieces, said permanent magnets being magnetized in circumferential direction;
(e) the width of the permanent magnets—measured in circumferential direction—is larger in the axially central portion of the rotor part than at the axial faces of the rotor part and the width of the magnetic flux conducting pieces—measured in circumferential direction—is correspondingly smaller in the axially central portion of the rotor part than at the axial faces of the rotor part;
(f) a first circumferential series of magnetic circuits which—as seen in a developed circumferential area—each extend through two adjacent stator poles of the first stator part in the circumferential area considered and through two adjacent magnetic flux conducting pieces of the rotor part in the circumferential area considered and through the permanent magnet between the two adjacent magnetic flux conducting pieces in the circumferential area considered, and a second circumferential series of magnetic circuits which—as seen in a developed circumferential area—each extend through two adjacent stator poles of the second stator part in the circumferential area considered and through two adjacent magnetic flux conducting pieces of the rotor part in the circumferential area considered as well as through the permanent magnet between the two adjacent magnetic flux conducting pieces in the circumferential area considered.
The electric machine according to the second subject matter of the invention differs from the electric machine according to the first subject matter of the invention in that the two air gaps (one air gap between the first stator part and the rotor part and a second air gap between the rotor part and the second stator part) are in two planes perpendicular to the rotor axis, whereas in the first subject matter of the invention there are provided two circumferential air gaps in radially spaced apart manner.
The electric machines according to the invention distinguish themselves by very high power density. This results from the presence of two stator parts and a common rotor part therebetween, but also from the geometry indicated of the magnetic flux conducting pieces and the permanent magnets. In addition thereto, the mutual “self-anchoring effect” of the components of the rotor parts is to be emphasized.
The electric machines according to the invention in particular may be machines outputting mechanical power (i.e. electric motors) or machines taking up mechanical power (i.e. generators). They are preferably electronically commutated electric motors or generators with take-off of electric power via active current converters.
In the first subject matter of the invention, the width mentioned of the magnetic flux conducting pieces radially inside on the rotor part and radially outside on the rotor part each is preferably smaller than the radial dimension of the particular magnetic flux conducting piece. In the second subject matter of the invention, the width mentioned of the magnetic flux conducting pieces on the axial faces of the rotor part each is analogously preferably smaller than the axial dimension of the particular magnetic flux conducting piece. This measure in both cases has the effect that the rotor part is designed in accordance with the magnetic flux concentration principle, i.e. a higher magnetic flux density is present at the exit of the magnetic flux conducting pieces to the corresponding air gap than in the respective magnetic flux generating permanent magnet.
In case of the first subject matter of the invention, the rotor part preferably is a constituent part of a cup-shaped portion of the rotor. In this case, the rotor can be designed so as to be supported on one axial side of the machine only, which has practical advantages for many fields of application.
Preferably, the cup-shaped portion of the rotor has a rotor base wall and the rotor part is mounted to the base wall via circumferentially distributed tie rods, with the tie rods being mounted on the one hand on the base wall and on the other hand extending through bores in the magnetic flux conducting pieces and/or the permanent magnets. This way of mounting by means of tie rods is particular advantageous in terms of production technology. It is pointed out that, due to the geometry mentioned of the permanent magnets and the magnetic flux conducting pieces, it is basically sufficient to directly fix either only the magnetic flux conducting pieces or the permanent magnets by means of the tie rods, since the respective other constituent parts, permanent magnets/magnetic flux conducting pieces, are held indirectly via positive engagement. On the other hand, it is indeed possible as well to secure both constituent parts, i.e. permanent magnets and magnetic flux conducting pieces, to the rotor base wall by means of tie rods each.
The magnetic flux conducting pieces and/or the permanent magnets may be subdivided, in the direction of the rotor axis, into a plurality of electrically isolated sections, which is preferred. These sections preferably can be adhesively joined to each other and/or be held together by tie rods. This reduces eddy current losses.
The magnetic flux conducting pieces and the permanent magnets preferably are subdivided, in the direction of the rotor axis, into a plurality of sections which are separated by intermediate rings of magnetically non-conducting material, which best should be electrically non-conducting as well. By means of this construction, it is possible to build rotor parts with increased mechanical strength. Between the respective intermediate rings, the magnetic flux cond
Dougherty Thomas M.
Kinberg Robert
Lam Thanh
Magnet-Motor Gesellschaft für magnetmotorische Technik mbH
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