Fuel system[edit | edit source]
Diesel fuel injection equipment[edit | edit source]
There are a number of different methods that have been used to inject diesel fuel into the cylinder or combustion chamber of diesel engines.
Mechanical injection pump[edit | edit source]
Jerk Pump (or unit pump system)[edit | edit source]
In-line[edit | edit source]
An in-line injection pump is basically a number of jerk pumps combined into one unit.
Rotary[edit | edit source]
Rotary injection pumps have a rotor that distributes the fuel to each cylinder in turn. There are two basic designs one in which the rotor also reciprocates to pump the fuel, the other, radial piston type, uses plungers pushed in towards the center of the rotor by an internally lobed cam ring.
Reciprocating rotor type[edit | edit source]
- Bosch VE rotary injection pump and licenced copies by Diesel Kiki, Zexel, Denso
- Bosch VP 37 and Bosch VP34 Bosch VE type pump with electronic control
- Bosch VP 30 and Bosch VP29 Bosch VE type injection pump with electronic control
- Zexel Covec
Radial piston type[edit | edit source]
Unit injector[edit | edit source]
The injection pump and injector are one unit
- Bosch Pumpe Duse- PDE electronically controlled unit injector
Common rail[edit | edit source]
Cold start and running systems[edit | edit source]
A number of different methods are used to improve combustion at cold starting and running and low load operation.
Glow plugs[edit | edit source]
Glow plug technology has developed over the years the latest technologies offer very quick heat up times and glow plug longevity. Combined with suitable control these plugs offer almost instant start and are activated after starting to improve cold running and low load operation.
glow plugs are also available with integral combustion sensors which provide feedback on combustion to the ECU (see below)
Inlet air heaters[edit | edit source]
A number of different methods have been used to heat the inlet air to increase cylinder temperatures and provide improved combustion.
Flame start system[edit | edit source]
Filament glow plug[edit | edit source]
Installed in the inlet tract an open hot wire element heats passing air
Heating flange[edit | edit source]
Installed in the inlet tract these electrical matrix heaters raise the temperature of air being drawn into the engine.
Engine management[edit | edit source]
Engine control unit - ECU[edit | edit source]
Engine control units (ECUs) are electronic embedded systems designed to control internal combustion engines. Largely to comply with emissions and fuel economy standards ECU's are now fitted to all the latest generation of production road transport vehicles, and increasingly engines used in other applications.
The ECU takes signals from a number of sensors fitted to the engine and uses the information obtained to control parameters such as timing and fuelling.
Engine parameters, such as fuel quantity and timing, can be modified to better suit the combustion characteristics of a given fuel. A number of options are available:
- using chip tuning techniques code in the ECU can be modified
- the sensor signals to the ECU can be modified to fool the ECU to behave in the desired manner
- the signals from the ECU to the engine can be modified to provide a more desirable result
- replace the ECU with a programmable version. see
Sensors[edit | edit source]
Combustion Sensors[edit | edit source]
In order to optimise combustion a number of companies are beginning to offer engines with combustion sensors fitted.
- Toyota were first to market in 1993 with a cylinder pressure sensor fitted to one cylinder of a lean burn Toyota Carina petrol engine.
- Delphi Multec Diesel Common Rail system uses Accelerometer Pilot Control (APC) - a knock sensor to assess combustion timing. Introduced in 2005 an claimed to be the first closed loop combustion control marketed for a diesel engine. This technology has been used in Ford Duratorq TDCi engines and Renault DCi engines.
- General Motors plans to offer a 2.9 V6 diesel Cadillac CTS cylinder pressure in 2009 which it claims will be the first production engine with cylinder pressure sensors.
- Audi have announced that they will also be the first to market in 2008 with diesel cylinder pressure sensors fitted to a 3.0 V6 Tdi engine to be offered in both the A4 and Q7.