Hydraulic hybrid

Principle of the hydraulic hybrid

The vehicle has a conventional internal combustion engine, the torque or drive power provides. In addition, in the drive train, at least one hydraulic motor is integrated, which is powered by a pressure accumulator (accumulator) refers. The pressure accumulator is filled with compressed gas and hydraulic fluid. Upon expansion of the gas, the oil is forced to flow through the hydraulic motor and into a container ( low-pressure accumulator ). During braking of the vehicle, a part of kinetic energy is recovered ( recuperated ) are integrated in the drive train by a pump pumps the oil from the low pressure reservoir back into the pressure accumulator. The gas bubble is recompressed in the pressure accumulator. Typically a hydrostatic piston machine is used as a motor. The same hydrostatic unit can be operated for the recovery of energy as a pump.

Take advantage of the hydraulic hybrid drive

Compared to a conventional vehicle having only an internal combustion engine the fuel consumption and the exhaust emissions can be reduced. This is achieved firstly by the recovery of the kinetic energy and on the other hand by the avoidance of unfavorable operating conditions for the engine. The energy recovery also reduces brake wear.

Types of hydraulic hybrid drive

As with the electric hybrid is possible to distinguish between serial, parallel or hybrid leistungsverzweigtem.

Advantages and disadvantages compared to the hybrid electric vehicles

The development of hydraulic hybrid vehicles always stood in the shadow of the development and market introduction of electric hybrid vehicles. Hydrostatic drive components are of comparable size and weight compared to electrical systems consisting of electric motor, inverter and battery is a very high performance, but they can provide for a very short time. The hydraulic hybrid thus has advantages when heavy vehicles need to be special frequently accelerated and decelerated again. Consequently, it was in the first production-based vehicles from different manufacturers to garbage trucks. A driving over longer distances without internal combustion engine is hardly possible in the hydraulic hybrid. Particularly in view of the expensive batteries of the electric hybrid hydraulic hybrid will be awarded cost advantages.