Direct fuel injection and injector detailing
Scheme of operation of injectors
Overview of electronic control systems for sensors, sensing elements and switches
1 – needle movement sensor (G 80); 2 – engine speed sensor (G 28); 3 – sensor for the amount of sucked air (G 70); 4 – coolant temperature sensor (G 62); 5 – temperature sensor in the suction line (G 72); 6 – Brake light switch and brake pedal switch (F 47); 7 – Clutch pedal switch (F 36); 8 – accelerator pedal position sensor (G 79); 9 – control valve trajectory sensor (G 149); 10 – additional signals: air conditioner and terminal + DF generator; 11 – engine glow plugs (Q 6) and glow plug relay (J 52); 12 – spark plugs for heating the coolant (Q 7) and high power heating relay N (J 359); 13 – spark plugs for heating the coolant (Q 7) and high-power heating relay (J 360); 14 – electromagnetic exhaust gas return valve (N 18); 15 – electromagnetic valve for boost pressure limitation (N 75); 16 – control lamp for pre-heating duration, control lamp (K 29); 17 – fuel quantity regulator; 18 – fuel shut-off valve (N 109); 19 – injection start valve (N 108); 20 – additional signals: engine speed signal, fuel consumption signal, air conditioner operation signal; 21 – Direct fuel injection control unit (J 248); 22 – diagnostic connector
Placement of electronic control elements in the engine compartment
Bracket Mounted Engine Accessories
1 – multi-groove belt; 2 – pulley mounting bolt; 3 – crankshaft pulley for multi-groove belt; 4 – belt tensioner housing mounting bolt; 5 – belt drive tensioner; 6 – generator; 7 – bracket; 8 – bracket mounting bolt (M = 45 Nm); 9 – power steering pump mounting bolt (M = 25 Nm); 10 – flow bolt (M = 30 Nm); 11 – sealing washer; 12 – pipeline eye; 13 – sealing washer; 14 – vane oil pump for power steering; 15 – bolt; 16 – pulley; 17 – pulley mounting bolt; 18 – generator mounting bolt
Trajectory of a multi-groove belt
A – belt trajectory in cars without air conditioning;
B – belt trajectory in cars with air conditioning
As already mentioned, the 1.9 TDI–66 kW engine has direct fuel injection into a chamber formed in the piston (see Fig. Direct fuel injection and injector detailing (sectional view)). The following figure, Injector Operation Diagram, shows the injectors in detail and how they work.
Five-hole injectors (hole diameter 0.17 mm) are screwed into the cylinder head and connected by steel tubes to the piston fuel pump. The pump is driven by a toothed belt transmission together with the timing gears and the coolant pump.
Control node
All functions listed in the electronic control system overview are controlled by the control unit via switches, namely based on signals and information from sensors and sensitive elements depending on the program and the driver's will. An overview of engine control elements is shown in Fig. An overview of electronic control systems for sensors, sensitive elements and switches, and their approximate placement is shown in Fig. Placement of electronic control elements in the engine compartment. The system has a self-learning adaptive control program; there is also a diagnostic program and, consequently, a terminal block for connecting diagnostic equipment.
The engine assembly also includes the following subassemblies:
The coolant pump, located in the crankcase cavity on the side of the timing gears, is driven by a toothed belt drive together with the timing gears. The pump is a compact assembly unit and, if damaged, is completely replaced at the service center. The impeller of the pump is of the turbine type. It is attached to the engine crankcase by a flange, which is part of the pump, screwed into the threaded holes in the block with two M8 bolts, which simultaneously fasten the protective casing behind the toothed belt drive of the pump drive. The pump is sealed to the block with a rubber washer. The pump bearings contain consistent grease.
Auxiliary equipment bracket (see Fig. Engine accessories mounted on bracket) is located on the left side of the engine (on the front side in the direction of travel). The bracket is equipped with: fuel pump, generator, power steering pump, belt tensioner, and air conditioning pump. The pulleys of the specified units are driven by a multi-groove belt. Its trajectory is shown in Fig. Multi-groove belt trajectory; A – version without air conditioning, B – version with air conditioning.