Machine Design

Squeezing power from brakes

One of the benefits of electric cars and some hybrids is that they can use regenerative breaking to recapture and store some of the power used in bringing cars and trucks to a stop.

 

Engineers at Shep Technologies Inc., in the U.K. (www.infinitebang.com/shepinc.com), have devised the Shep system (stored hydraulic energy propulsion) to do the same for conventional internal-combustion-powered vehicles. The system also provides the stored energy when it is needed most, when the vehicle accelerates from a dead stop (when the engine is at its least efficient and emitting the most pollutants).

The Shep system has three major components: a pump, tank, and controller. The Ifield motor-pump attaches to the driveshaft. The pump "grabs" the spinning driveshaft to slow the vehicle during braking. According to Ford Motor Co., this alone should boost brake life by 77%. The pump transfers the energy to a unitized accumulator, a hydraulic tank that stores pressurized fluid. Energy is sent back to the pump, helping it turn the driveshaft when the vehicle accelerates from a dead stop. An electronic controller uses software to determine when to run the pump and in which direction. In a test vehicle, a 2001 Lincoln Navigator, Shep improved fuel economy by 38% going from 13 to 18 mpg, added 85 hp to its dead-stop acceleration, taking it from 275 to 360 hp, and cut dirty emissions by 50%. The company is tight-lipped on when consumers might see it in the showrooms.

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