scholarly journals An Investigation into In-Cylinder Tumble Flow Characteristics with Variable Valve Lift in a Gasoline Engine

2014 ◽  
Vol 94 (2) ◽  
pp. 285-304 ◽  
Author(s):  
Tianyou Wang ◽  
Daming Liu ◽  
Bingqian Tan ◽  
Gangde Wang ◽  
Zhijun Peng
2007 ◽  
Author(s):  
Hiroshi Tagami ◽  
Yuji Yasui ◽  
Masahiro Sato ◽  
Hisashi Ito

Author(s):  
Shiqiang Zhang ◽  
Chunshu Li ◽  
Ruilin Liu ◽  
Jingyang Bao ◽  
Miao Chi

The in-cylinder gas flow is an important factor that affects the engine performance. The appropriate swirl can reduce cycle-to-cycle variations, increase flame propagation speed, and improve the combustion efficiency. Many technologies can induce significant swirl, but lead to intake flow loss. In this research work, the variable valve lift difference adjustment mechanism is developed to obtain and adjust in-cylinder swirl without weakening flow capacity in a four-valve gasoline engine. The in-cylinder swirl and tumble characteristics generated by the variable valve lift difference adjustment mechanism are studied by means of experiment and simulation. The results of the experiment and simulation show the intensity of tumble and swirl under the larger lift valve is increased with the increase in the phase difference between two intake cams at same camshaft angle, and a large-scale swirl is formed in the cylinder when the camshaft angles change from 40° to 80°, and another large scale swirl is formed during the camshaft angles change from 100° to 140°, but the rotating direction of the secondary swirl is inverse to that of first swirl. The scale and shape of the in-cylinder tumble and swirl are not changed significantly with the increase in the phase difference between two intake cams when the camshaft angles change from 80° to 100°. A brief discussion on the research results that improve the performance of actual gasoline engine is given.


2004 ◽  
Author(s):  
Frank Himsel ◽  
Christof Faria ◽  
Peter Solfrank ◽  
Ulrich Grau ◽  
Uwe Geiger

Author(s):  
Burak Gecim ◽  
Madhusudan Raghavan

We review variable valve actuation (VVA) concepts and also present the results of our work in the creative synthesis of these devices. We begin with a comprehensive survey of existing VVA devices. We then describe our work on four VVA concepts which we have explored in considerable detail. These include hydraulic lost-motion variable-lift systems, in both the direct acting and the roller-finger-follower configurations, several valve deactivation mechanisms with unique features, a variable valve-lift mechanism, and a variable-lift and duration concept. These devices differ in their complexity and versatility but offer a spectrum of design solutions applicable to a range of products. The strengths and weaknesses of these different approaches are discussed and analyzed, and some test results are presented.


Sign in / Sign up

Export Citation Format

Share Document