Research on the Electromagnetic Valve Used in Medium Pressure Common Rail Electronically Controlled Fuel Injection System

A new kind of electromagnetic valve [1], with great flow and fast speed, used in the medium pressure common rail electronically controlled fuel injection system of diesel engine is introduced for the first time. It is a kind of Two-position, Three-way Valve (TTV) that consists of a valve body, an outer valve rod and two inner valve rods. The electromagnet can generate great electromagnetic force because of its assembled magnetic fields. It actuates the outer valve rod from its closed-position to the open-position rapidly. A spring is used to push it back. Fuel injection begins when the outer rod is in the open position and ends in the closed. The inner and outer valve rods with taper valve port replace the traditional configuration and decrease the difficulties in machining. Finite element method has been used to analyze the electromagnet’s electromagnetic fields. Static characteristics of the electromagnet are calculated. Some factors such as working area, coil turns, core number, armature depth and iron material that influence the magnetic force are discussed in detail. The magnetic material and the electromagnet dimensions are optimized according to calculation results. Meanwhile, the leakage between the valve body and the outer valve rod, the leakage between the outer valve rod and left-inner valve rod and the leakage between the outer valve rod and the right-inner valve rod are also studied by the finite element method. Key part that causes the leak during operation has been found out and improvement is carried out. Influences of the TTV to the injection timing and the injection amount are analyzed in detail based on the Fuel Injection Test Platform (FITP) in the end.