Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
1999-01-04
2001-06-12
Tamai, Karl I. (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C310S237000, C310S136000, C310S151000, C310S154090, C310S241000
Reexamination Certificate
active
06246146
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to an electric direct current machine.
2. Description of the Related Art
An electric direct current collector machine, which can be used as a motor as well as a generator, is known (for example, from DE 33 24 617 A1). For this collector machine, a rotor, carrying a plurality of non-ferrous coils of electrical conductors at uniform angular intervals on the same diameter, is rotatably mounted in one housing. On the inner sides of the end surface of the housing, rigidly disposed permanent magnets of polarity, differing consecutively in the circumferential direction, are located opposite to and on either side of the coils. The conductors, forming the coils, are connected in turn to commutator contact surfaces, which rotate with the rotor and are insulated electrically from one another and on which sliding contacts, which are provided in the housing and insulated from the wall of the housing and which are connected conductively with external electrical connections, are pressed. When connected to an electric direct current source, the machines, so constructed, act as a motor. On the other hand, when the rotor shaft is driven, they act as a generator, that is, electrical direct current can be collected from their terminals. These known direct current machines find use, for example, as small, very compact motors of low output, for example, as motors for driving recording devices for video signals. Because of the special arrangement of the rotor coils and the permanent magnets and the therefrom resulting course of the interacting fields of the permanent magnets and the rotor coils, such motors are also referred to as axial field machines. Because of the good efficiencies that can be attained with them and because of the basically good possibilities of regulating them, such axial field machines, with larger dimensions and a correspondingly higher output, have also been proposed, for example, as driving motors for vehicles (WO 95/17779).
SUMMARY OF THE INVENTION
It is an object of the invention to further the development of such an electric direct current machine with higher outputs, which makes it also suitable as driving motors for vehicles, so that the machine, while having a simple and therefore cost-effective construction, achieves a high efficiency.
Pursuant to the invention, this objective is accomplished by an electric direct current machine with a rotor, which is rotatably mounted in a housing, has a plurality of electromagnets mounted at a distance from the axis of rotation, with in each case a coil winding on a coil core carrying one or more electrical conductors, the ends of the electrical conductors, forming the coil, being taken radially inward and being connected in an electrically conductive manner with, in each case, assigned contact elements having in each case one contact surface and, taken together, forming a commutator, onto which contact elements sliding contacts are pressed, which are held in the housing and can be connected to a source of direct current or to a direct current consumer, and with pole faces of permanent magnets, which are disposed at regular angular distances on the inner sides of the end walls of the housing opposite the end faces of the coil cores and, consecutively in the circumferential direction, have opposite polarities, each coil core forming with the associated coil winding a separately produced electromagnet component, which is held in a hub support, which is connected with the shaft of the rotor so that there can be no mutual rotation, the pole faces of the permanent magnets extending so that they overlap in each case several opposite coil cores, the two sliding contacts of the commutator, assigned to a radially external permanent magnet, extending so far in the circumferential direction, that they overlap the contact surfaces, of in each case, about half of the contact elements assigned to a pole face of a permanent magnet, and contact surfaces being provided, which are offset to the contact surfaces of the contact elements forming the commutator and connected electrically with the respective contact surfaces on the commutator side and against which sliding contacts are pressed, which essentially correspond in the circumferential extension to the sliding contacts of the commutator and in turn are connected electrically with one another in each case in pairs.
The prefabrication of the electromagnet components and their subsequent mounting in the hub support ensures the desired simple construction and the cost-effective mounting. Due to the refinement that in each case several electromagnet components are assigned to each permanent magnet, it is possible to energize the electromagnet component, which runs into the field of a permanent magnet when the rotor is running, in such a manner, that they have an opposite polarity and thus are attracted by the electromagnet in the circumferential direction. As soon as the coil core of the respective electromagnet component is then aligned centrally to the permanent magnet, the polarity of the coil core is reversed over the contact surfaces opposite to the commutator contact surfaces, as a result of which the electromagnet component then has the same polarity as the opposite permanent magnet and is thrust further in the direction of rotation.
At the same time, it may be appropriate if the contact surfaces of the sliding contacts of the commutator and the contact surfaces of the sliding contacts, which are assigned to the commutator sliding contacts and connected electrically with one another in pairs, can be shifted relative to one another by a specified amount in the direction of rotation of the rotor. In this way, the effective contact surface of sliding contacts of the commutator in the circumferential direction and, with that, the characteristics of the direct current machine can be changed.
Preferably, the coil cores have the shape of essentially rectangular disks, which extend radially and parallel to the rotor axis and the edge regions of which protrude with the radially extending end edges over the coil winding carried by them. These protruding edge regions of the coil cores then act—particularly if they are aligned in the radial direction—like radial blades of a blower, which enables a motor to be cooled by aspirating from the surroundings in the radially inner region of the housing and blowing it out in the radially outer region of the housing. The radial and disk-shaped construction of the coil cores furthermore makes it possible to provide a large number of electromagnet components on a specified diameter, especially if the machine in question is developed on the axial field principle with a relatively large diameter and does not extend very far axially. Moreover, an optimum utilization of space is attained if the coil cores of a sectional plane, placed at right angles through the rotor shaft, has a cross section diverging from the radially inner boundary edge to the radially outer boundary edge.
The electrical conductors of an electromagnet component can be formed from an extended electrical conductor, such as a metal strip of a copper alloy, which is passed in at least a half turn around the coil core. A rotor, assembled from such electromagnet components, then has sufficient inherent stability, that is, it requires no or only a skeleton-like rotor framework, so that air can flow well through the electric conductors and the rotor can thus be cooled.
Alternatively, the electrical conductors of the electromagnet components can also be formed from a plurality of electrically conducting metal wires, which lie next to one another and are passed around the coil core in at least half of a winding.
The coil cores of the electromagnet components can be disposed at a radial distance from and essentially parallel to the axis of rotation of the rotor.
Alternatively, the coil cores of the electromagnet components can also be disposed at a radial distance from and inclined at such an angle to the axis of rotation of the rotor
Norris McLaughlin & Marcus P.A.
Tamai Karl I.
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