Liu Fushui

Gasoline engine idle speed control system development based on PID algorithm

One of the often-running modes for a gasoline engine is idling, and idle speed stability is one of the key aspects to evaluate a vehicles performance when it is equipped with a gasoline engine. Therefore, it is very important to control the idle speed stability and to keep the idle speed constant in spite of the various engine load disturbances. In order to reach this goal, usually the closed loop control is applied. Among various control algorithms, traditional PID algorithm has been used successfully for many applications. The key advantages of PID control are its simplicity and practicality. Its control parameters can be tuned on line; the flexibility of its software development makes it easier to get a better control result. In this paper, based on PID control algorithm, an idle speed control system for 462Q electronic controlled gasoline engine is developed. The hardware design of this system, the design of the digital PID controller, the selection of the sample interval and the method for tuning the control parameters are introduced in detail.

A micro-processor based adaptive ignition control system

An adaptive ignition control system can adjust ignition angle automatically, so the power of the SI engine is improved while preventing it from knock. This paper describes an ignition control system, whose core is a micro-processor (80C552). The inputs include intake manifold pressure sensor, throttle position sensor, water temperature sensor, crankshaft position (speed) sensor, synchronization sensor and knock sensor. The software of the system includes main flow program and several interruption programs. The article describes how the knock signal acquisition, knock condition judgment, ignition-signal, etc. are controlled by the software. The peak-value of the knock signal is recorded in a circuit during one cycle, and accordingly this value of the knock is detected. A new two-parameter ignition angle adjusting method is used, which is according to the peak-value of knock signal during one cycle and the mean value of several cycle peak-values. This method effectively resolved the contrast of the high response and small cycle fluctuation of ignition angle control. The experiments on 368Q engine shows that the design of the system hard-and-software is feasible and the engine is prevented from knock effectively, the torque of the engine is improved.

Experimental Researches on the Characteristics of Dense Spray of Diesel Engine

The mean methods of improving performance of modern diesel engine include increasing speed, increasing cycle fuel injection quantity, increasing fuel injection pressure and intake boosting technology, so that more fuel quickly mixing with in cylinder air in shorter time is requested. For solving these problems, the spray characteristics under the high injection pressure and high ambiance density must be detailedly studied. A series of experiment researches of dense spray characteristics were presented in this paper. The experiments were carried out in a constant volume chamber specially designed, which can hold a high ambiance pressure and temperiture. The high-speed photography was used to study the macroscopic characteristics of spray, including the spray penetration and cone angle. The Particle Image Velocimetry was used to study the spray velocity field.

Optical Experimental Study on Knock Characteristics of Hydrogen-Air Pre-mixture

By means of schlieren method and gas pressure measurement, knock characteristics of hydrogen-air pre-mixture has been studied in constant volume combustion chamber. The effects of initial temperature, initial pressure and equivalence ratio on flame development process and pressure characteristics have been investigated. The experimental results show that knock caused by auto-ignition of unburned gas appears firstly in the angle region between the spherical flame front and the wall of combustion chamber on this paper’s condition, detonation occurs easilier with higher temperature, higher pressure and higher equivalence ratio, the higher the initial temperature is, the faster the pressure rises, but the lower the peak pressure is, pressure increases faster and meanwhile peak pressure is higher according to higher initial pressure, severe knock emerges on the conditions of low temperature and high pressure.

On the Evaporation Characteristics of Multi-droplets of Diesel by Experimentation

In order to study the mutual influence in the process of droplets evaporation, the evaporation phenomena of single droplet, double-droplets and multi-droplets were studied experimentally in this paper. Firstly, the influence of background temperature on single droplet evaporation rate was contrasted to verify the reasonableness of the experimental system. And then, the influence of number of droplets was studied by comparing the value of evaporation rate for each experimental condition. It can be found that when the number of droplets increases, the evaporation rate of droplets decreases.

Experimental Study on the Match between Electronic Unit Pump and Diesel Engine

An injection system of Delphi Electronic Unit Pump (EUP) matched speed-down cam profile was employed to study on the effect of EUP pre-lift on the match between EUP and diesel engine. It can be found that the EUP pre-lift has direct effect on the match between EUP and diesel engine as the prelift determines the effective operation range of the constant pressure segment (CPS) of EUP. When the EUP works in the CPS, the two items of the maximum injection pressure (MIP) and the fuel delivery per cycle (FDPC) keep the same. If not, both of them decrease significantly. In addition, it is found the pre-lift of 11.5mm is more suitable of the match between the EUP and a V-type eight-cylinder turbocharged diesel engine according to its variation laws of the specific fuel consumption (SFC) and the maximum combustion pressure (MCP) with the injection advance angle (IAA).

Design for Control System of Wastegate Valve Actuator in Turbocharger

This paper has designed a set of control system of waste gate valve actuator in turbocharger, it enables the waste gate valve regulate the exhaust flow before turbo automatically according to the operating condition of engine, so it can lower the pressure ratio and prevent the compressor surge occurrence when the compressor is in small flow. In this paper, it elaborated the regulation principles using waste gate valve, designed the electronic control unit and simulation system and tested the function and reliability of the whole control system.

Simulation Investigation on the Multiple Injections of Two-Actuator Controlled Fuel Injection System

The multiple injection characteristics of two-actuator controlled fuel injection system(two-actuator system) were investigated in this paper, which was established by the Electronic Unit Pump and Common Rail injector to realize the way to independently control the pumping and injection processes. The two-actuator system simulation model was validated and the results indicated consistency between the calculative and the experimental one. Consequently, the model is capable of predicting the characteristics of two-actuator system and plays an extension and complementarity role for experiments, The simulation results of multiple injections illustrated that two-actuator system enables to generate different nozzle opening pressure efficiently and produce a very flexible control of injection rate through changing control parameters of both SCV and NCV.

Experimental Analysis on the Characteristics of Two-Actuator Controlled Fuel Injection System

The characteristics of two-actuator controlled fuel injection system which is established by the Electronic Unit Pump and Common Rail injector to realize independent controlling the pumping and injection processes are investigated from the point of experimental analysis. The experimental results indicate that high pressure up to 130Mpa can be generated on the advance two-actuator system at low camshaft speed. Meanwhile, synchronous variations of the pumping and injection timing have little influence on the fuel pressure and injection rates, the reason for this phenomenon is that fuel injection characteristics here are mainly determined by the cam lift and velocity. Two-actuator system enables to generate the desired Nozzle Opening Pressure timely and produce a very flexible control of injection rate through changing control parameters of both Spill Control Valve and Nozzle Control Valve, which have great capabilities on fuel atomization and air-fuel mixture formation.

An Improved Constant Volume Combustion Bomb with Built-in Adaptor

In this article an improved constant volume combustion bomb with built-in adaptor is developed for improving the performances of ventilation and fire resistance. The adaptor contains an array of vias. By changing the tightening torque between the small bolt of each via and the corresponding nut the flow area of adaptor can be adjusted. With using the equipment, the auto-ignition characteristics of hydrogen is studied by means of schlieren method and gas pressure measurement, which is used to verify its good performances. The experimental results show that the bomb can efficiently block the flame propagation from the upper combustion chamber to the lower one under the promise of ensuring that the pressure and unburned gas of the upper one transmit successfully to the lower one, and the evident spontaneous combustion can be more intuitively simulated in the lower combustion chamber.