A VARIABLE DISPLACEMENT MECHANISM FOR INTERNAL-COMBUSTION ENGINES

The concept of load control in internal combustion engines by eliminat ing the inlet throttle and replacing it by controlling the piston stro ke has gained great publicity recently. Nevertheless, certain design p arameters should be considered in order to make this concept worthwhil e. In this study, an optimized mechanism for varying engine stroke has been introduced. A criteria based upon the use of complex numbers tec hnique was used to analyze the mechanism kinematically and dynamically and the results were then verified using graphical solution. The mech anism was found to produce up to 56% stroke variation within the contr ol actuator capabilities. The compression ratio was found unchanged (w ithin +/- 6%) which helps maintain steady combustion process. The enti re mechanism is well tuned and no spark plug timing adjustment is requ ired during stroke variation. The piston side thrust due to connecting rod angularities was found fairly low and should not impose any wear problems in the engine cylinder walls.