EJBR02401Z Diesel Fuel Injector 33800-4X800 for Hyundai Terracan Kia Carnival Kia Sedona

Modelling the High-speed Injector for Diesel ICE （part 4）

The increase in the speed of the EHI ensures a shorter delivery time and, consequently, mean injection pressure and control flow, a reduction of the minimum stable delivery. At first glance, closing of the needle without the multiplier may be accelerated by tightening the spring, but the fundamental difference of this solution is the constant closing force, i.e. with the accelerated closing, opening will be decelerated as well. Therefore, an equally efficient structure may not be obtained by increasing the mechanical closing force of the needle as compared to the multiplier; and in case of low effort, the EHI becomes unstable.

According to the known results of the study [6] of the EHI the speed limitation is conditioned by a wide range of injection pressures, as well as by the deviation of the real supply conditions from the requirement. However, the above statement is invalid regarding the EHI operating at a constantly high pressure. Transition to a constant pressure allows considering several options for increasing the injector operating speed:

1 increasing the rigidity and tension of the return spring, which gives it an additional compensating function as applied to the growing needle opening force acting on the tip of the needle;

2 decreasing the diameter of the multiplier piston with the corresponding decrease in the volume of the control chamber;

3 reducing the cross-sections of the bypass throttle and the sealing section of the control valve, with a corresponding additional reduction in traction force and an increase in the operating speed of the solenoid valve.

To analyse the above possibilities for increasing the operating speed, the one-dimentional LMS Imagine.Lab AMESim [7,8] package was selected. Bosch 0445110190 electrohydraulic injector with a solenoid control valve and the dimensions of the seat, contact part of the needle and the outlets (Table 1), corresponding to the atomizer of the YAZDA 33.1112010-03 serial injector for the KamAZ-7409 engine was selected as the initial design of the model (Fig. 2). According to the assumed method, simulation was performed using models with an operating inlet pressure of 100 MPa.