Numerical evaluation of idle parameters of novel throttle body for internal combustion engines

Abstract

The paper investigates and evaluates the idle speed parameters of a novel throttle body for internal combustion gasoline engines. Where the classic throttle bodies utilize a butterfly type valve, a new design has been investigated utilizing a completely different approach in an attempt to eliminate the drawbacks of butterfly type valves. The advantages of the novel design include no obstructions or resistances in the flow-path at fully open throttle position, flow jet centered in the channel cross-section and a slight one-way valve effect at partial throttle openings. Other changes required for the new design include a slightly altered fuel injector angle, a different idle air bypass system and increased leakage at fully closed throttle position. The aim of this study is to evaluate the effects of these design changes on a Honda CRF450R motorcycle at idle speed or fully closed throttle position. Steady state computational fluid dynamics analysis at constant pressure differential was carried out in SolidWorks Flow Simulation environment, where idle speed leakage values were compared between the original butterfly type and the novel design, particle studies were conducted to determine the fuel injection properties. It was found that the novel throttle body is theoretically capable of providing normal idle operation, however, the manufacturing processes should be carefully considered due to the increased leakage at fully closed throttle position. The fuel droplets injected at idle speed tend to travel with greater velocity compared to the original butterfly type throttle body.