Systems and methods for rotor shaft grounding
Methods and systems for grounding a rotor of an electric machine. The electric machine system includes a rotor shaft, a grounding cover coupled to an end of the rotor shaft, and a cam aligned with a rotational axis of the rotor shaft and electrically coupled to the grounding cover. The electric machine system further includes an end plate of a housing and a spring extending between the cam and an interior surface of the housing, where the grounding cover, the cam, and the spring are electrically conductive.
1 . An electric machine system, comprising:
a rotor shaft;
a grounding cover coupled to an end of the rotor shaft;
a cam coaxially aligned with a rotational axis of the rotor shaft and electrically coupled to the grounding cover;
an end plate of a housing; and
a spring extending between the cam and an interior surface of the housing;
where the grounding cover, the cam, and the spring are electrically conductive;
where the rotational axis extends through a face of the cam and the spring; and
where the face of the cam is in face sharing contact with a portion of the grounding cover through which the rotational axis extends.
2 . The electric machine system of claim 1 , where the cam includes a recess that mates with an end of the spring.
3 . The electric machine system of claim 1 , where the grounding cover is splined to the rotor shaft.
4 . The electric machine system of claim 1 , where the grounding cover is interlocked to the rotor shaft.
5 . The electric machine system of claim 1 , where the grounding cover is staked to the rotor shaft.
6 . The electric machine system of claim 1 , where the grounding cover includes a metallic conduit that extends therethrough.
7 . The electric machine system of claim 1 , where:
the housing includes an inwardly protruding portion that includes a recess; and
an end of the spring is mated with the recess.
8 . The electric machine system of claim 1 , where the grounding cover and the housing form a sealed cavity.
9 . The electric machine system of claim 8 , further comprising a magnet positioned in the sealed cavity.
10 . The electric machine system of claim 1 , where the electric machine system is a traction motor.
11 . A method for operation of an electric machine system, comprising:
rotating a rotor shaft while the rotor shaft is electrically grounded;
where the electric machine system includes:
the rotor shaft;
a grounding cover coupled to an end of the rotor shaft;
a cam coaxially aligned with a rotational axis of the rotor shaft and electrically coupled to the grounding cover; and
a spring extending between the cam and an interior surface of a housing;
where the grounding cover, the cam, and the spring are electrically conductive;
where the rotational axis extends through the cam and the spring; and
where the face of the cam is in face sharing contact with a portion of the grounding cover through which the rotational axis extends.
12 . The method of claim 11 , where the grounding cover and the housing form a sealed cavity and the electric machine system further comprises a seal that is positioned between the rotor shaft and the housing.
13 . An electric motor, comprising:
a rotor shaft;
a grounding cover coupled to an end of the rotor shaft;
a cam electrically coupled to the grounding cover;
an end plate of a housing; and
a spring extending between the cam and an interior surface of the end plate and aligned with a rotational axis of the rotor shaft;
where the spring and the cam are aligned with a rotational axis of the rotor shaft;
where the grounding cover, the cam, and the spring are electrically conductive; and
where the spring includes:
a first end mated with a first recess in the cam; and
a second end mated with a recess in an inwardly protruding section of the end plate.
14 . The electric motor of claim 13 , where:
the end plate comprises a radially extending protrusion that has an inner surface with a first groove which has a first seal positioned therein and an outer surface with a second groove which has a second seal positioned therein; and
the first seal and the second seal contact an extension of an end of the rotor shaft.
15 . The electric motor of claim 13 , where the grounding cover is splined, interlocked, and/or staked to the rotor shaft.
16 . The electric motor of claim 13 , where the grounding cover is positioned outboard of a rotor shaft bearing.
17 . The electric motor of claim 13 , where the grounding cover and the end plate form a sealed cavity.
18 . The electric motor of claim 17 , further comprising a collection device positioned in the sealed cavity.
19 . The electric motor of claim 18 , where the collection device includes a magnet.