Electric drive unit with encapsulated field windings and seal member
An electric drive unit having an electric motor, which has a rotor and a stator that includes a stator core and field windings, a housing assembly into which the electric motor is received, and a seal member. The stator core defines a plurality of stator cooling passages that extend longitudinally through the stator core. Each of the field windings has a protruding portion that extends from an axial end of the stator core. The protruding portions are encapsulated in a plastic material. The housing assembly has an annular wall member that defines a seal groove. The seal member is received in the seal groove and forms a seal between the annular wall member and the plastic encapsulation on the protruding portion of the field windings. A coolant is circulated through the stator cooling channels, and the seal member inhibits ingress of the coolant between the stator and the rotor.
1. An electric drive unit comprising:
an electric motor having a stator and a rotor, the stator including a stator core, and a plurality of field windings, the stator core defining a plurality of stator cooling passages that extend longitudinally through the stator core, each of the field windings being associated with a corresponding phase of electrical power, the field windings having a protruding portion that extend from an axial end of the stator core, the rotor being rotatable relative to the stator about a motor axis; and
a housing assembly into which the electric motor is received, the housing assembly having a motor housing and a motor housing cover, the motor housing having an annular wall member that is disposed about the stator core, the motor housing cover being mounted to the motor housing to close an end of the motor housing;
a bearing holder coupled to the motor housing cover;
a bearing received between the bearing holder and the rotor for supporting the rotor for rotation about the motor axis;
an inverter mount having an annular side wall, the annular side wall being coaxially disposed about a portion of the rotor and being received within the housing assembly along the motor axis between the stator core and the motor housing cover, the inverter mount defining a cooling fluid passage that is in fluid communication with the stator cooling passages;
a first seal member received on the bearing holder and forming a seal between the annular side wall and the bearing holder.
2. The electric drive unit of claim 1 , further comprising a second seal member disposed between and sealingly engaging the inverter mount and the annular wall.
3. The electric drive unit of claim 2 , wherein the inverter mount defines a seal groove into which the second seal member is received.
4. The electric drive unit of claim 1 , further comprising a plurality of power semiconductors and a plurality of heat sinks, each of the power semiconductors being mounted to the inverter mount and being disposed about the bearing holder, each of the heat sinks being mounted to a corresponding one of the power semiconductors and being disposed in the coolant chamber.
5. The electric drive unit of claim 4 , further comprising plurality of bus bars including a positive bus bar, a negative bus bar and a plurality of phase bus bars, the bus bars being electrically coupled to the power semiconductors, each of the phase bus bars being electrically coupled to an associated one of the field windings, wherein the inverter mount has a base that segregates the coolant chamber from an annular cavity into which the busbars are received.
6. The electric drive unit of claim 4 , wherein the power semiconductors are disposed radially outwardly of the protruding portion of the field windings.
7. The electric drive unit of claim 4 , wherein an annular field capacitor is disposed radially outwardly of the protruding portion of the field windings.
8. The electric drive unit of claim 1 , wherein the inverter mount defines a coolant standpipe through which the cooling fluid passage is formed.