Engine Vacuum System - As-Built Configuration - GF07.09-P-0800OM
ENGINES 651.9
Schematic representation of the vacuum system, engine 651.913/925
Function
The vacuum pump is driven by the crankshaft via the gear drive and generates the required vacuum. The exhaust gas recirculation cooler bypass switchover valve and the coolant pump switchover valve is connected with the vacuum pump via vacuum hoses and lines.
If the exhaust gas recirculation cooler bypass switchover valve is actuated by a pulse width modulated signal (PWM signal), performance map dependent, the vacuum acts on the exhaust gas recirculation cooler bypass vacuum unit and opens the bypass in the exhaust gas recirculation cooler via a linkage.
If the coolant pump switchover valve is actuated by means of a PWM signal, performance map dependent, the vacuum acts on a power diaphragm fitted in the coolant pump. This power diaphragm moves the regulating valve via control rods and closes the flow of coolant to the coolant pump.
Both switchover valves are ventilated with ambient pressure via the respective ventilation connection with filter.
Schematic representation of the vacuum system, except engine 651.913/925
Function
The vacuum pump is driven by the crankshaft via the gear drive and generates the required vacuum. The vacuum pump is connected to the vacuum reservoir via a vacuum hose.
The vacuum reservoir is connected to the following components via vacuum hoses and lines:
- - Boost pressure control pressure transducer
- - Boost pressure control flap pressure transducer
- - Exhaust gas recirculation cooler bypass switchover valve
- - Charge air bypass flap switchover valve (up to 06/10)
- - Coolant pump switchover valve
If the boost pressure control pressure transducer is actuated by means of a pulse width modulation (PWM) signal performance map dependent, the vacuum acts on the boost pressure control vacuum unit and opens the wastegate in the low-pressure turbocharger continuously so that part of the exhaust flow bypasses the low-pressure turbocharger and is fed into the exhaust system.
If the boost pressure control flap pressure transducer is actuated by means of a PWM signal according to a performance map, the vacuum acts on the boost pressure control flap vacuum unit and opens the boost pressure control flap in the high-pressure turbocharger steplessly so that part of the exhaust flow bypasses the high-pressure turbocharger and is fed to the low-pressure turbocharger.
If the exhaust gas recirculation cooler bypass switchover valve is actuated by means of a PWM signal according to a performance map, the vacuum acts on the exhaust gas recirculation cooler bypass vacuum unit and opens the bypass in the exhaust gas recirculation cooler via a linkage.
If the charge air bypass flap switchover valve is actuated by means of a PWM signal, performance map dependent, for vehicles up to 06/10 the vacuum acts on the charge air bypass flap vacuum unit and opens the bypass in the charge air pipe between the high-pressure and low-pressure turbocharger via a linkage so that part of the generated charge air of the low-pressure turbocharger bypasses the high-pressure turbocharger.
For vehicles as of 06/10 a modified turbocharger with a pressure-dependent self-regulating compressor bypass is used. The spring-loaded check valve takes on the work of the charge air bypass flap switchover valve with an associated vacuum aneroid capsule.
If the coolant pump switchover valve is actuated by means of a PWM signal, performance map dependent, the vacuum acts on a power diaphragm fitted in the coolant pump. This power diaphragm moves the regulating valve via control rods and closes the flow of coolant to the coolant pump.
The 2 pressure transducers are ventilated with ambient pressure via a common vent filter.
The 3 switchover valves are ventilated with ambient pressure via the respective ventilation connection with filter.