An improved alternator for use with motor vehicles and for supplying AC current for the operation of the motor vehicle in response to a DC exciting current being supplied to the alternator from a source of exciting current, the improved alternator comprising:
- a rotor assembly;
- a rotor shaft that has a longitudinal axis that has a first end and a second end, with the first end having a distal end portion, that is rotatable about the longitudinal axis, that is connected with the rotor assembly so that the rotor assembly is disposed radially outwardly from the longitudinal axis of the rotor shaft and so that the rotor assembly and the rotor shaft rotate together about the longitudinal axis and that includes electric leads which are electrically conductive to the exciting current which are connected with the rotor assembly and which extend toward the distal end portion of the first end of the rotor shaft, with the first end of the rotor shaft being made of a non-electrically conductive material;
- a stator assembly disposed in relationship to the rotor assembly so that upon the supply of exciting current to the rotor assembly and the rotation of the rotor assembly relative to the stator assembly, AC current is generated by electromagnetic cooperation between the rotor assembly and the stator assembly;
- and
- a contact assembly including:
- first and second bearing assemblies that are disposed adjacent to the first end of the shaft, that are spaced longitudinally, along the longitudinal axis, from each other and that are electrically isolated from each other;
- each of the bearing assemblies having:
- an outer race member that is relatively fixed with respect to the rotor shaft, that is disposed radially adjacent to and radially outwardly from the first end of the rotor shaft, and that is electrically conductive to the exciting current;
- an inner race member that is mounted on and rotatable with the first end of the rotor shaft, that is disposed adjacent to and radially inwardly from the outer race member, and that is electrically conductive to the exciting current, with the inner and outer race members defining, radially therebetween, an annular volume;
- the contact assembly further including first and second electrically conductive members that are mounted on a first portion and a second portion, respectively, of the first end of the rotor shaft so that the first and second conductive members rotate with the rotor shaft and so that the first conductive member and the second conductive member are in electrical contact with the inner race member of the first bearing assembly and the inner race member of the second bearing assembly, respectively, with the first and second conductive members being connected with the electrical leads which are connected with the rotor assembly;
- and each of the bearing assemblies further including a plurality of rolling, relatively moveable members that are electrically conductive to the exciting current, that are radially disposed in the annular volume and that permit the inner race member, with the rotor shaft, to rotate relative to the outer race member with relatively minimal friction therebetween, with the inner and outer race members and the rolling members being radially aligned, with respect to the longitudinal axis, with the rolling members occupying a portion of the annular volume between the inner and outer race members, and with an electrically conductive grease being packed in the annular volume and about the rolling members so as to substantially fill portions of the annular volume not occupied by the rolling members and so that the rolling members and the grease provide the electrical connection for the exciting current between the inner and outer race members.