BACKGROUND OF THE INVENTION

1. Field of the Invention

The present disclosure relates to electrical machines, and more particularly to winding separators for electrical machines such as motors, generators, and motor/generators.

2. Description of Related Art

For some types of electrical machines (motors and generators) the stator windings are subjected to extreme thermal conditions over long periods of time due to continuous duty cycle and self-heating. It is well understood that the insulation life of the windings (e.g., magnet wire enamel and impregnation) is inherently reduced with exposure to extreme temperature over long periods of time. General practice to extend winding insulation life is to reduce winding temperatures as much as practical through the management of heat rejection, e.g., through active and/or passive cooling.

Active cooling can include convection cooling. Examples of convection cooling include the use of cooling air directed over the machine housing, which can include heat transfer fins, from a shaft mounted fan or through the use of a cooling fluid routed through a sealed jacket mounted around the periphery of the machine housing. Passive cooling can include conduction through the various components of the machine to the outer frame and associated structure to which the machine is mounted. Generally, heat rejections schemes include both passive and active methods.

The conventional techniques have been considered satisfactory for their intended purpose. However, there is an ever present need for improved heat rejection in electric machines. This disclosure provides a solution for this need.

SUMMARY OF THE INVENTION

An electric machine includes a winding yoke defining a plurality of winding slots between circumferentially spaced apart teeth. A respective winding separator is mounted within each of the winding slots. The winding separator is mounted to a keying feature that extends from the winding yoke into the winding slot.

The winding yoke can be a laminated structure, wherein the teeth and keying features are part of a common laminated structure with the winding yoke. The winding yoke can be part of a stator, and a rotor can be mounted within the stator for rotary movement relative to the stator.

A first winding phase can be seated in each winding slot and a second winding phase can be seated in each winding slot. The first and second winding phases can be separated from one another by the respective winding separator. The winding separator can include at least one of thermally conductive ceramics and/or plastics.

The keying feature can be in intimate thermal contact with a keying receptacle of the winding separator. Thermal paste can be included between the keying feature and the keying receptacle. The keying feature can include a neck that extends radially into the winding separator and a head extending radially from the neck that is wider than the neck. The keying feature can have a constant cross-sectional shape as a function of position in an axial direction.

Each tooth can include a pair of circumferentially spaced apart walls that are parallel to one another, and the winding separator can have a triangular axial cross-sectional shape separating the winding slot into two sections with constant spacing between the winding separator and circumferentially adjacent teeth. It is also contemplated that each tooth can include a pair of circumferentially spaced apart walls that are not parallel, giving the tooth a trapezoidal axial cross-sectional shape, and the winding separator can have a rectangular axial cross-sectional shape separating the winding slot into two sections with constant spacing between the winding separator and circumferentially adjacent teeth.

A method includes punching a layer of material to form a layer of an electric machine yoke. The layer of an electric machine yoke is punched to include a keying feature circumferentially between each pair of a plurality of circumferentially spaced apart teeth of the layer of an electric machine yoke.

The method can include individually punching at least one additional layer of material to form a plurality of layers of an electric machine yoke, wherein each layer of an electric machine yoke is punched to include a keying feature circumferentially between each pair of a plurality of circumferentially spaced apart teeth of the layer of an electric machine yoke. The method can include joining the layers of the plurality of layers of an electric machine yoke to form a yoke lamination for an electrical machine. Joining the layers can include joining the layers to form a stator yoke for an electric machine.

These and other features of the systems and methods of the subject disclosure will become more readily apparent to those skilled in the art from the following detailed description of the preferred embodiments taken in conjunction with the drawings.

