CAT HEUI System Introduction - F-DIESEL FUEL INJECTION ELECTRONIC SYSTEM

CAT HEUI System Introduction

F-DIESEL FIE SYSTEM 8/1/2021 3:03:01 am

[Key Words] CAT repair kit CAT HEUI System

The HEUI fuel system is mainly composed of fuel delivery pump, first and second class fuel filter, fuel pressure regulating valve, hydraulic drive electronic control unit injection pump, hydraulic oil supply pump, hydraulic oil line, electronic control unit and Fuel return pipe, hydraulic oil pipe and other components, in addition, hydraulic oil pressure sensor, hydraulic oil temperature sensor, fuel temperature sensor, throttle position sensor, fuel pump control valve signal sensor, etc. are also used in the system.

1. The working principle of HEUI system engine
The hydraulic electronic control fuel injection system is the HEUI system. The system is mainly composed of fuel supply pump unit, electronic control unit ECM, throttle controller, speed, formal sensor, fuel injector, temperature sensor and pressure sensor.
The hydraulic oil supply pump group provides driving pressure to the fuel injector. Under normal conditions, the oil is pressurized to 50~21.5MPa by the high pressure oil pump to drive the fuel injector. The pressure level is controlled by the ECM used to send a signal to the pump.
The electronic control unit ECM is the core component of the engine. The ECM has functions such as speed regulation, timing and fuel limitation, and at the same time reads the signal of the sensor through the data line and connects to the instrument display system. The throttle sensor provides the driver with engine speed control. The engine is set to run at a low idle speed for 2 seconds when starting, so that the oil pressure rises before the engine accelerates. This system eliminates all the mechanical connections between the speed control and the governor and eliminates the possibility of wear of the traditional linkage system.
The speed/timing sensor includes two sensors, the main and the auxiliary, which are used to detect the engine speed, timing, identify the cylinder and top dead center TDC. If the primary timing sensor fails, the system will immediately activate the secondary timing sensor and generate a fault code at the same time.
The electronic fuel injector is ECM controlled and driven by high-pressure hydraulic oil. The maximum fuel pressure can reach 150MPa. The fuel injection quantity determines the length of the fuel injection time and the size of the fuel injection driving pressure.

2. Features of HEUI system
(1) Medium-pressure common rail electronically controlled hydraulic injection system, the common rail oil pressure is 4~23MPa, the oil pump outputs low pressure oil 300KPa to the high-pressure oil pump (swash plate axial piston pump), and the common rail is controlled by ECU The pressure regulating valve in the middle reaches the best performance value;
(2) Diesel engine lubricating oil is used instead of fuel in the system, and there are two sets of lubricating oil and fuel oil circuits;
(3) The fuel supercharger piston is driven by the common rail oil pressure of the engine oil to boost the fuel and achieve high-pressure fuel injection. The size of the supercharger piston is 7:1 and the injection pressure can reach 150MPa;
(4) Use the high-speed switch solenoid valve to control the oil in and out of the supercharger piston in the common rail oil passage to realize the increase and decrease of fuel pressure, so as to realize the timing control of fuel injection;
(5) Pre-injection is achieved by using preset injection holes to control the initial injection rate;
(6) Fuel injection pressure has nothing to do with diesel engine speed and load.

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