I know how to adjust fuel injection timings of MC engines.
But, In CR(Common rail engine) I don't know how to adjust it.
The only thing that I know is it is controlled by solenoid valve.

and, It is possible to control fuel injection timing on engine side? Is there any cam shaft or fuel rack in high pressure pump?

The high-pressure pump on a common-rail system does only one thing ... pressurize the fuel in the fuel rail. It has nothing to do with injection timing, it just pressurizes the rail and holds the pressure at a regulated setting.

Injection timing on a common-rail engine is done purely by controlling the timing of the pulses to the injectors, and therefore, the only way to "adjust" it is to change the mapping in the computer. It is otherwise non-adjustable. Same situation as ignition timing in newer gasoline engines with no distributors.

The original poster's question was a valid one.  And since he mentioned "fuel rack", it's safe to assume he's talking about a diesel CR high-pressure injection pump.

Controlling rail pressures and flows in a mass-produced 180 bar fuel injection system is actually quite complex.  The rail pressures are very high, the flow volumes are very low, the working fluid is incompressible, and the pump output flows must be continuously varied and corrected at a very high frequency rate. 

High pressure CR diesel pumps are mostly variable displacement piston pumps.  With the displaced volume (per cycle) being controlled by a PW modulated, high-frequency solenoid inlet valve, and a check valve on the discharge side.

Rail pressure control is critical with these very high pressure injection systems, since a small change in relative rail pressures (ie. 26KSI versus 28KSI) can have a huge impact in injector nozzle mass flows.  Rail pressures, nozzle orifice diameters and edge geometries, all can have a big impact on fuel mass flows when the injection pressures are 28KSI.

Diesel engines don't require the stringent A/F ratios that a gasoline engine needs.  But they still have very sophisticated ECU's and software control laws.  A modern piezo-actuated diesel automotive injector is capable of producing up to five separate injection events per cycle, at over 180 bar.  Thus each injection event must occur in less than 0.20 milliseconds and is sequential.  Pretty impressive.

The typical diesel DI injector control basically has two parameters: Beginning of Injection (BOI) and injection duration (PW).  These parameters are controlled by the ECU which uses sensor inputs such as engine temps, air temps, engine speeds, engine loads, manifold pressures, rail pressures, etc., and calculates the correct injector driver values based on mapped software tables, algorithms, and control laws.  Some of the more sophisticated ECU's are even capable of modifying these values based on data acquired over the life of the engine.

High pressure CR pumps are basically operating with the same controls as the injectors.  The main difference between diesel injection controls and gasoline injection controls, is that gasoline injection systems really require a closed loop type system.  Where there is instrumentation feedback from devices like O2 sensors in the exhaust, and air mass flow sensors in the intake, to correct the A/F ratios.

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