The concept of a hydraulic hybrid powertrain is not a new one, and a number of companies have developed prototypes. The latest to show off a vehicle so equipped is Artemis Intelligent Power in the UK. The company has put together a BMW 530i demonstrator using its Digital Displacement pump/motor technology. The layout is very similar, in principal, to that used by FEV on its experimental UPS delivery vans. In this configuration, there is no direct connection between the engine and drive wheels. Instead, the engine drives a hydraulic pump that charges a hydraulic pressure accumulator in a series hybrid layout. The pressurized fluid stored in the accumulator is used to drive a pair of hydraulic motors at the rear axle that actually drive the wheels.

Like an electric hybrid, under braking, the drive motors are used to pressurize the accumulator. The company claims this is a more cost-effective solution than batteries. While the system can capture kinetic energy quickly - like an ultracapacitor - the energy storage capacity of the accumulators is unfortunately limited, making this configuration less useful for cars, particularly in highway driving. The series hydraulic hybrid is best suited to urban-use trucks like delivery vans or buses where there is more room for the accumulators. Artemis claims a 50 percent reduction in urban fuel consumption on its demonstrator vehicle. The key difference that Artemis is claiming for its version is the design of the hydraulic pump motor which is claimed to provide greater efficiency and more precise control. You can check out a video after the jump.

[Source: Artemis Intelligent Power]

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