Abstract: A rotor assembly for a turbomachine having a permanent magnet electric motor that defines an axis of rotation includes a jacket member. The rotor assembly also includes a magnet member that is received within the jacket member. The magnet member has a first longitudinal end and a second longitudinal end that are separated along the axis of rotation. The rotor assembly also includes a first shaft structure that is attached to the first longitudinal end and a second shaft structure that is attached to the second longitudinal end.

Abstract: A tool system for stress relieving a turbocharger turbine wheel longitudinally welded to a hardened rotor shaft. The shaft has a journal bearing region and a turbine-end body forming an A datum surface for receiving an axial bearing. The tool system includes an induction coil and an electronic oscillator, and a tool. The tool forms an opening configured to receive the rotor shaft such that the journal bearing region of the shaft extends into the tool housing while the A datum surface adjoins an end of the tool housing. The induction coil is positioned around the turbine-end body. The housing forms an annular cooling chamber surrounding the journal bearing region of the shaft. The housing forms an inlet passage to provide cooling fluid to the annular chamber, and an outlet passage to remove cooling fluid from the annular chamber.

Abstract: A unit for a turbocharger can include a turbine wheel portion that includes a turbine wheel material and a turbine wheel axis; a shaft portion that includes a shaft material and a shaft axis; a first weld that includes a first average axial position over a first azimuthal span and first weld composition formed of a greater proportion of the turbine wheel material than the shaft material; and a second weld that includes a second average axial position over a second azimuthal span and second weld composition formed of a greater proportion of the turbine wheel material than the shaft material, where a sum of the first azimuthal span and the second azimuthal span is approximately 360 degrees, where the first average axial position differs from the second average axial position, and where the first weld composition differs from the second weld composition.

Abstract: A unit for a turbocharger can include a turbine wheel portion that includes a turbine wheel material and a turbine wheel axis; a shaft portion that includes a shaft material and a shaft axis where the shaft material includes a molybdenum content less than 0.5 percent by weight; and a weld that includes a nail shape in cross-section where a head portion of the nail shape includes an axial dimension of approximately 1 mm or less and wherein a shank portion of the nail shape includes an axial dimension of approximately 0.4 mm or less.

Abstract: A tool system for stress relieving a turbocharger turbine wheel longitudinally welded to a hardened rotor shaft. The shaft has a journal bearing region and a turbine-end body forming an A datum surface for receiving an axial bearing. The tool system includes an induction coil and an electronic oscillator, and a tool. The tool forms an opening configured to receive the rotor shaft such that the journal bearing region of the shaft extends into the tool housing while the A datum surface adjoins an end of the tool housing. The induction coil is positioned around the turbine-end body. The housing forms an annular cooling chamber surrounding the journal bearing region of the shaft. The housing forms an inlet passage to provide cooling fluid to the annular chamber, and an outlet passage to remove cooling fluid from the annular chamber.

Abstract: A method can include co-axially locating a turbine wheel and a shaft where a force applicator applies an axially directed force to the turbine wheel, where the turbine wheel transfers at least a portion of the force to shaft and where a rotatable shaft collet supports the shaft; rotating the rotatable shaft collet; energizing at least one laser beam; and, via the at least one laser beam, forming a weld between the turbine wheel and the shaft.

Abstract: A system can include a controller; a force applicator; a rotatable shaft centering collet; a drive mechanism that rotates the rotatable shaft centering collect; and a laser beam unit.

Abstract: A method can include co-axially locating a turbine wheel and a shaft where a force applicator applies an axially directed force to the turbine wheel, where the turbine wheel transfers at least a portion of the force to shaft and where a rotatable shaft collet supports the shaft; rotating the rotatable shaft collet; energizing at least one laser beam; and, via the at least one laser beam, forming a weld between the turbine wheel and the shaft.

Abstract: A unit for a turbocharger can include a turbine wheel portion that includes a turbine wheel material and a turbine wheel axis; a shaft portion that includes a shaft material and a shaft axis where the shaft material includes a molybdenum content less than 0.5 percent by weight; and a weld that includes a nail shape in cross-section where a head portion of the nail shape includes an axial dimension of approximately 1 mm or less and wherein a shank portion of the nail shape includes an axial dimension of approximately 0.4 mm or less.

Abstract: A unit for a turbocharger can include a turbine wheel portion that includes a turbine wheel material and a turbine wheel axis; a shaft portion that includes a shaft material and a shaft axis; a first weld that includes a first average axial position over a first azimuthal span and first weld composition formed of a greater proportion of the turbine wheel material than the shaft material; and a second weld that includes a second average axial position over a second azimuthal span and second weld composition formed of a greater proportion of the turbine wheel material than the shaft material, where a sum of the first azimuthal span and the second azimuthal span is approximately 360 degrees, where the first average axial position differs from the second average axial position, and where the first weld composition differs from the second weld composition.

Abstract: A system can include a controller; a force applicator; a rotatable shaft centering collet; a drive mechanism that rotates the rotatable shaft centering collect; and a laser beam unit.