PNEUMATIC HYBRID ENGINE SYSTEMS

COŞKU KÖKE BAYRAMCAN İNCE

Components of Pneumatic Hybrid Engine System

• Conventional ICE

• Low pressure air tank (20 bar, 20 liter)

• Turbocharger(Compressor and Turbine)

• Variable valve actuation system for charge valve (e.g. EHVS in Fig.)

Pneumatic Hybridization

• Since the late 1990s, pneumatic hybridization of ICEs has been discussed.

• The key idea is the recuperation of some of the

energy that vehicle must lose.

• In addition to the recuperation capability, the idea offers the possibility of a rapid start/stop.

• This can be realized by connecting an air pressure tank to all cylinders via electronically controlled charge valves.

ECU Diagram

Modeling of Operation Modes

• Combustion Engine Mode

Conventional ICE mode

• Several Pneumatic Modes

Supercharged Mode

Undercharged Mode

Pump Mode

Motor Mode

Conventional ICE Mode

DUAL CYCLE

Pneumatic

Supercharged Mode

• For operating points at which the turbocharger does

not yet provide enough air.

• Combustion mode that additionally uses pressurized air and additional fuel to boost the engine.

• Amount of additional air in the cylinder is determined by the tank pressure and the timing of the short opening of the charge valve.

• Used for transients only to overcome the turbo lag.

Pneumatic Supercharged Mode

The shaded region above corresponds to the recuperated energy.

Pneumatic Undercharged Mode

• The excess air is used to fill the tank.

• Half of the cylinders combust, the other half is pumping air into the tank.

• Charge valve is opened when the cylinder pressure is equal to the tank pressure .

• Amount of air remaining in the cylinder is determined by the duration of the opening.

• For safety reasons a direct fuel injection system is crucial.

Pneumatic Pump Mode

• Recuperation of the kinetic energy during the braking.

• Engine is used as a pump.

• Air tank is filled.

• The timing of the charge valve closing is very important because of down stroke .

Why CoP?

• The increase of the internal energy is not only caused by the engine work output, but also by the free enthalpy of fresh air inducted by the engine.

• Higher torques would be possible but it became an optimization problem around the parameters:

Throttling

Backflow

Heat transfer

Pneumatic Motor Mode

• Uses compressed air only for propulsion .

• Enables a fast stop-start, stop&go operations .

No engine idling saves fuel

• !!! Load control is effected by varying CVC and EVC simultaneously.

• This modes thermodynamic cycle is the reverse of the pneumatic pump modes cycle.

• In contrast to the pump mode, we get the range of feasible torque much wider.

Advantages of HPE

Fuel saving > 30% proven (NEDC)

Cost Efficiency

Immediate Torque Response

No Turbo Lag

Low emissions

Driveability

Down-sized the engine

Fuel Economy

Technology Choices

THANKS A LOT

REFERENCES

• Lino Guzzella · Antonio Sciarretta

Vehicle Propulsion Systems

• Guzzella MTZ(Research)

• Paper-Pneumatic hybrid engine with exhaust heat recovery