Digital Displacement® Hybrid Transmission Benefits

Rather than using electric motors and batteries like most other hybrid cars, a Digital Displacement® Hybrid vehicle uses hydraulic motors to drive the wheels and compressed gas to store energy. The hydraulic transmission is potentially much more durable, lighter and cheaper than electric hybrids.

An enabling technology

Many other companies are investigating hydraulic hybrid technology, in both series and parallel configurations. The reasons for this haven't changed for a number of decades:

• hydraulic drives and energy storage have high power density compared to electric alternatives;
• hydraulic systems have a long-established reputation for robustness and longevity in countless industrial applications;
• hydraulic components tend to be relatively easy to manufacture and are well-suited to mass production - and therefore cheap.

The main problem has always been, until now, the part load efficiency of hydraulic pumps and motors, meaning that they are only seeing adoption in very specialised applications (refuse trucks, city buses and so on) - and even then, results are mixed at best. Digital Displacement machines is the enabling technology for hydraulic hybrids because its efficiency remains high throughout its operating range. Cars spend little of their lives at full power, so DD's part load efficiency is particularly suited to the automotive duty cycle.

• Regenerative braking with accumulator storage

  Storing reclaimed energy in a hydraulic accumulator greatly improves urban cycle efficiency.
  

• Engine off operation

The vehicle can start moving using energy stored in the accumulator without any engine power at all, allowing the engine to stop when in traffic yet retaining immediate response to accelerator pedal input.

All Wheel Drive and Rear Wheel Drive cars no longer need a driveshaft to transfer power from the front of the vehicle to the rear wheels, increasing the interior space and giving vehicle designers more freedom.