Cheap oil is a thing of the past. That’s why everybody and their collective mothers are trying to figure out ways to make vehicles burn less fuel. Chrysler’s working with the EPA to make nifty hydraulic hybrid transmission . . . that’s actually been around for ages.
Chrysler, along with GM, Mercedes, and BMW, spent billions developing the Hemi-based Two-Mode V8 hybrid. The system uses complex computer-controlled transmission that determines how to split power between the engine and electric motor in real time. Two-Mode hybrid systems appeared in large Chrysler and GM SUVs. They worked well, but the behemoths didn’t deliver press-worthy MPG figures. Plus, the system isn’t used in tiny commuter cars.
Enter Chrysler’s partnership with the EPA. The dynamic, publicly funded duo are co-opting a hybrid system commonly used in industrial trucks. As you can see, from the nice illustration above, it’s a hydraulic system that captures energy from braking in the form of compressed hydraulic fluid. In stop-and-go traffic the system builds up a heap of pressure, which can be used to drive the car at low speeds. When the brake pressure wanes, the engine drives a pump to keep pressure up in the system. The system actually decouples the engine from the driveline. Hydraulic pressure alone spins the wheels. That means the engine can be stopped and stared while driving, just like an electric hybrid. But there’s a huge bonus: No batteries.
Hydraulic hybrid systems have been used for ages in delivery and refuse trucks and are proven to be rock-solid and very efficient.
Chrysler is testing their system in a Town & Country minivan with a 2.4-liter inline four. No word on how much gas the system saves, but Chrysler has high hopes. If it pans out, the system could be a great way to increase fuel economy without decreasing power or increasing cost (that much).