Typically, hydraulic hybrids are used for very heavy vehicles where the impact on drivability of the energy recovery is acceptable. Dana’s controls engineering expertise was engaged to develop controls to demonstrate good drivability on a light weight passenger car vehicle. Dana controls engineering implemented an energy blending strategy that provided a very smooth transition between the combustion engine, the energy storage device and the brakes.
In order to control the engine, an electronic throttle body was used, together with an OpenGateway intervention on the engine CAN bus to define the engine torque requirements based on available stored energy and driver demand.
To control the brakes, Dana implemented its own novel electro-hydraulic brake solution (a modification that can be used for any vehicle requiring regenerative braking) based the OpenECU™ rapid prototyping controller. This interfaced to some additional hydraulic parts, operating in conjunction with the foundation brake system.
The system is approximately 70% efficient so every time the system cycles it is saving 70% of the energy that would have been dumped as heat. This is immediately seen as a fuel saving.
However, the hidden benefits of much cleaner emissions (the petrol engine does less work at low RPM where it is inefficient and dirty), reduced brake wear, an apparently larger engine etc. are not insignificant either.
1 year+ / ongoing