Type system «Common Rail» makes it possible to combine the diesel fuel injection system with various remotely performed functions, and at the same time allow to improve the accuracy of controlling the fuel combustion process. The purified outside air, after a variable geometry turbocharger with air-to-air intercooling, enters the cylinders under pressure. As a result, its temperature decreases, and the degree of filling in the cylinder increases.
A distinctive feature of the system with a pressure accumulator is the separation of the pressure generating unit and the injection unit, which makes it possible to increase the amount of fuel injection pressure and the degree of its atomization. The basis of the type system «Common Rail» makes up the high pressure fuel pump (NVD), hydraulic accumulator (ramp) fuel with its connections to the injectors (electromagnetic nozzles) and electronic control system type «DDE». Injectors provide the right amount of fuel to the combustion chamber at exactly the right time, which is calculated by the electronic control unit (ECU). The amount of injected fuel is determined by the time interval of the open state of the injector, at a constant pressure in the system.
The engine of this series is six-cylinder, in-line, installed vertically in the car. It uses a 24-valve gas distribution mechanism (timing), with overhead camshafts (DOHC system) and lever drive of vertically arranged valves. The clearance in the valve drive is compensated by supporting the lever on the hydraulic compensator. The shafts are driven by a roller chain through the crankshaft sprocket.
With severe engine overcooling and low ambient temperature, air compression cannot always provide the temperature for self-ignition of the fuel. When starting a cold engine, the volume of the combustion chambers is heated by a glow plug for 30 seconds. In parallel with the heating of the combustion chamber, automation provides earlier fuel injection at the time of start-up. With engine operating temperature setting (85 - 95°С) automation sets the optimal feed start angle (injection) fuel. Regulation of the start of fuel injection and its quantity is provided by the program of the electronic control unit «DDE» (Digitalt Diesel-Elektronik), digital engine management system (Tssud) based on a personal minicomputer. per system «DDE» tasks are also assigned to regulate the amount of boost pressure and ensure the standards of exhaust gas toxicity.
The fuel supply from the vehicle tank is provided by a fuel priming pump installed in the fuel tank. At increased loads, fuel is supplied to the HP from the main (intermediate) fuel pump, which provides a constant pressure in the system 1400 kgf / cm2 necessary for spraying the injected fuel. The amount of injected fuel and the order in which it enters the chambers is determined by the system ECU «DDE».
BMW X5 series diesel car model «M57» And «M57TU» has an index «530d». The design of the engines is identical, except for their control systems. The technical parameters of the engines are given below.