Borgwarner Inc.

Ecomotors, Inc.

Christopher Meszaros

Tyler R Garrard

Will Robert Nielsen Hippen

Diana D Brehob

Will R Hippen

A system and method is provided for controlling an electric machine rotatably coupled to a rotatable shaft of an electronically-controlled one of a turbocharger and an exhaust-driven turbo supercharger fluidly coupled to an exhaust duct of an internal combustion engine. An operating temperature of a component of the engine is determined or estimated an operating temperature of a component of the engine or coupled to the engine, which is compared to a threshold temperature. The electric machine is controlled to operate as a motor in response to the determined or estimated temperature of the component being below a threshold temperature.

System and method for controlling an electronically-controlled turbocharger

By relieving the shaft of an electronically-controlled turbocharger (ECT) in a central region of where a rotor of an electric machine couples with the shaft eases assembly of the electric machine onto the shaft. On either side of the relieved section, the fit between the shaft and the rotor may be a slip fit or an interference fit. Alternatively, the rotor is relieved in a central section. In some embodiments, the shaft is welded to the rotor. In yet other embodiments, the outside of the shaft and the inside of the rotor are threaded with a nut or a pin to secure the shaft to the rotor or the rotor itself has threads to engage with threads on the shaft. Such arrangements ease assembly and allow adjustment of dynamic characteristics of the rotor system.

Electric rotor fit onto a turbomachine shaft

It is common in electric machines to use the housing as a heat sink to remove energy from the electric machine. In some applications, however, the housing receives energy from a hot element. For example, in an electronically controlled turbocharger, the very hot turbine housing radiates and conducts energy to the electric machine housing exacerbating the heating within the electric machine. To reduce the heat transfer into the electric machine, a gap is provided between the stator and the housing outside the stator. In one alternative, the gap is filled with an insulating material. In another embodiment, the gap is an air gap with the stator located within the housing by circumferential rings or axial rods in corresponding grooves. In yet another embodiment, coolant is provided to the gap at the top and drained away at the bottom under the action of gravity.

Insulation in an electric machine

Performance of an electric motor can be improved if coolant is provided to the coils of the stator. An electric motor is disclosed that has a shaft onto which the rotor is secured. The motor has a stator that is mounted on bearings that are mounted on the shaft. The stator has a plurality of coils. A coolant guide is provided that fills voids between the groups of windings. The coolant guide has a plurality of fingers with the fingers arranged between adjacent pairs of coils. The coolant guide has internal passages to accept pressurized coolant and outlet holes to spray coolant onto the coils. In other embodiments, the fingers guide coolant to reach all coils under the force of gravity.

Cooling stator coils of an electric motor

An electronically-controlled turbocharger (ECT) includes a rotor (of an electric motor) on the shaft of the turbomachine. There are a variety of embodiments for securing the rotor onto the shaft including, but not limited to: having a taper on both the shaft on the rotor and using a nut engaging with threads in the shaft to put the two tapers together; a press fit; splines and grooves also using a nut; and a shoulder on the shaft that the rotor abuts when a nut is engaged with threads on the shaft. To accommodate these retaining features, the diameter of the shaft is greater near the turbine end of the shaft. A first bearing installed on the shaft near the turbine end of the shaft has a larger inside diameter than a second bearing installed on the other side of the rotor.

Bearings for a turbomachine having an electric motor

In an electric machine, there may be lubrication and cooling needs, such as lubricating bearings and cooling coils of the electric machine. When lubricant is used for both, it is desirable to prioritize the lubrication to the bearings. By providing check valves between a pressurized oil manifold and the cooling coils, lubricant is diverted to the coils only when pressure in the system is sufficient to satisfy both lubrication and cooling. In some embodiments, an oil gallery is provided on an outside surface of a back iron of the stator of the electric machine and orifices are provided in the back iron so that oil drips onto the coils of the electric motor. In some embodiments, the current commanded to the electric motor is based on whether or not lubricant (or other coolant) is being provided to the coils.

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Brighton, MI, United States of America

Christopher Meszaros