The shutdown procedure function is described using engine 926.9 (6 cylinders) as an example.
G07.15-A024-79
0 | Ignition OFF | Y49 | Hydraulic constant throttle solenoid valve (only for 6 cylinder engines) | |
1 | Circuit 15R ON | Y600 | Cylinder 1 single injection pump | |
2 | Circuit 15 On | Y601 | Cylinder 2 single injection pump | |
3 | Circuit 50 | Y602 | Cylinder 3 single injection pump | |
A3 | Drive control (CPC) control unit | Y603 | Cylinder 4 single injection pump | |
A6 | Engine management (MR) control unit | Y604 | Cylinder 5 single injection pump | |
B15 | Crankshaft position sensor | Y605 | Cylinder 6 single injection pump | |
B16 | Camshaft position sensor | Y617 | Pneumatic constant throttle solenoid valve | |
CAN 4 | Drive train CAN | A | Input signals | |
S1a | Ignition lock | B | Output signals | |
S11 | Engine stop button |
General
The engine can be stopped:
Via an appropriate shutdown request over the drive train CAN
With the ignition lock
Using the engine stop button
Function
As soon as the engine management (MR) control unit receives an appropriate shutdown request over the drive train CAN or the engine stop button or the ignition lock is actuated while the engine is running, it interrupts the actuation of the single injection pumps for cylinders 1 to 6 and the fuel is delivered directly to the fuel return. Since no further injection takes place, the engine cuts out.
To prevent the engine from switching off accidentally, the engine stop button must be held down until the engine stops. If the engine stop button is released before the engine speed has fallen below 50 rpm, the engine starts up again. The engine management (MR) control unit detects the engine speed on the basis of the signals from the crankshaft position sensor and the camshaft position sensor.
To accelerate the shutdown procedure, the engine management (MR) control unit also actuates the hydraulic constant throttle solenoid valve, which is only installed with 6 cylinder engines.
At the same time, the engine management (MR) control unit transmits the request to actuate the pneumatic constant throttle solenoid valve to the drive control (CPC) control unit over the drive train CAN. The drive control (CPC) control unit actuates the pneumatic constant throttle solenoid valve directly.
6 cylinder engine
Through the actuation of the hydraulic constant throttle solenoid valve, the throttle valves in the cylinder head are opened hydraulically.
Through the actuation of the pneumatic constant throttle solenoid valve, the engine brake flap is closed via a pneumatic cylinder downstream of the exhaust gas turbocharger.
4 cylinder engine
Through the actuation of the pneumatic constant throttle solenoid valve, the throttle valves in the cylinder head are opened pneumatically and the engine brake flap is closed via a pneumatic cylinder downstream of the exhaust gas turbocharger.
After the shutdown procedure, the engine management (MR) control unit is supplied with voltage for at least another 10 s. This period, the so-called run-on phase, is used to write information to the permanent fault memory.
For engines with BlueTEC, the AdBlue® metering device is ventilated by the engine management (MR) control unit in the run-on phase (max. 300 s), which prevents frost damage as a result of the AdBlue® freezing.
Engine management (MR) control unit, component description | A6 | ||
Component description for the crankshaft position sensor | B15 | ||
Component description for camshaft position sensor | B16 | ||
Engine stop button, component description | S11 | ||
Hydraulic constant throttle solenoid valve, component description | 6 cylinder engine | ||
Single injection pump, component description | Y600, Y601, Y602, Y603, Y604, Y605 | ||
Pneumatic constant throttle solenoid valve, component description | Y617 |