MAN - Continuously Variable Engine Braking

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MAN Truck & Bus Press Release  /  May 11, 2016

Maximum engine braking power for demanding drivers The MAN Turbo EVBec engine brake is a special further development of the engine brake for the D38 engine series. Variable exhaust valves upstream of the turbo chargers ensure higher backpressure when braking and enable a targeted air flow to the turbo charger blades to increase the turbine speed of the turbo charger on the exhaust side and thus also on the intake side. The pressure level in the engine is raised and the brake output increases.

Background:

MAN EVB (exhaust valve brake) enables powerful, wear-free braking and controlled downhill driving at high speeds with up to 290 kW of braking power. The engine braking power increases when the exhaust valves are opened briefly. A further improvement is the pressure-controlled MAN EVBec. This provides an even greater braking torque at lower speeds.

MAN EVBec extends the normal EVB function to enable continuously variable brake output. This is achieved by regulating the exhaust back-pressure with the butterfly valve in the exhaust pipe. The air-actuated engine brake valve closes the exhaust pipe in a stepless process depending on the desired brake output, thus generating the exhaust back-pressure required for the cylinders. The vehicle management computer (FFR) measures the current exhaust back-pressure from a sensor and uses a proportional valve to ensure that the servo-cylinder is accordingly triggered by pressure. The staged response of the sustained-action braking equipment permits regulated use when driving. Smooth, jerk-free braking can be achieved in this way.

The impressive combination of the powerful EVBec engine brake and the MAN PriTarder^® water retarder creates an efficient and economical brake system. In contrast to a conventional retarder the water retarder works directly with the water from the cooling circuit.

As is the case with the intarder, the MAN PriTarder^® is incorporated into the MAN BrakeMatic^® sustained-action braking management system. When shifting/declutching, the service brake is activated so that the braking power is not interrupted during gear changes (reblending).

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