Recent GM Patent Application Reveals Electric Turbochargers
General Motors has filed a patent application for a turbocharging system with electric motors.
The American automaker isn’t the first one to express interest in electric turbochargers, but the extensive patent details benefits of the technology. The application involves a two-turbo setup: a low-flow turbocharger driven by the post-combustion gasses from the first outlet to pressurize the airflow and a high-flow turbocharger driven by the post-combustion gasses from the second outlet. From there, the turbocharging system includes a motor-generator to selectively assist the post-combustion gasses in driving either the low-flow or the high-flow turbocharger, while generating electric current when driven by the subject turbocharger.
In addition, the patent application notes an additional second motor-generator that could be configured to selectively assist the post-combustion gasses in driving the other of the low-flow turbocharger or high-flow turbocharger and to generate electric current when driven via the other turbocharger. So essentially, a two-stage turbocharging system with two electric motors isn’t out of the question.
What’s most interesting about the patent application is the ability for the electric motors to generate electrical power, possibly to charge a battery pack.
“Once the rotational speed of the engine has reached a value at which the flow of post-combustion gasses is sufficient to drive the low-flow turbocharger, the operation of the low-flow turbocharger will be sustained by the exhaust flow and the first motor-generator can be switched off,” it says in the patent application. “On the other hand, once operation of the low-flow turbocharger can be sustained by the exhaust flow, the first motor-generator can be operated in the generator mode, such as during highway cruising of the vehicle. Additionally, because the high-flow turbocharger is sized for operation at higher flow rates of the post-combustion gasses, electrical assist to the high-flow turbocharger for transient engine/vehicle maneuver is likely to be less frequent, as compared with the above-described electrical assist to the low-flow turbocharger. However, the second motor-generator in the low-pressure turbocharger can be operated more frequently in the generator mode for electrical power generation.”
The patent application was filed on August 27, 2015 but wasn’t published until March 2, 2017. In 2015, AutoGuide.com detailed how the Volkswagen Group has been working on developing electric turbochargers, and it’s possible Audi will still be one of the first automakers with a production vehicle using the technology. But now the German automaker has competition and it’s likely GM isn’t the only one.