Title: Development of a variable-profile cam to enhance the volumetric efficiency of IC engines

Authors: Ali Sürmen; Rıdvan Arslan; Osman Kopmaz; Atakan Avcı; İrfan Karagöz; M. İhsan Karamangil

Addresses: Faculty of Natural Sciences, Architecture and Engineering, Department of Mechanical Engineering, Bursa Technical University, Bursa, 16190, Turkey ' Vocational School of Technical Sciences, Department of Automotive, Uludağ University, Bursa, 16059, Turkey ' Faculty of Engineering, Department of Mechanical Engineering, Uludağ University, Bursa, 16059, Turkey ' Faculty of Engineering, Department of Mechanical Engineering, Uludağ University, Bursa, 16059, Turkey ' Faculty of Engineering, Department of Mechanical Engineering, Uludağ University, Bursa, 16059, Turkey ' Faculty of Engineering, Department of Automotive Engineering, Uludağ University, Bursa, 16059, Turkey

Abstract: In this study, it is aimed to develop a new concept camshaft for continuously variable valve timing (CVVT). The concept is based on obtaining a curvilinear cam surface by integrating a number of conventional cam contours. Thirteen unworked camshafts, with arbitrary different contours, i.e., valve opening and closing times, were machined and tested on a four-stroke single-cylinder diesel engine to determine their volumetric efficiency at varied engine speeds. Then with suitable axial arrangement of these individual contours on a camshaft and integration of them, a single curvilinear cam surface was obtained. It is expected to get the same volumetric efficiency, with a ball contact follower when it follows a specific contour, as obtained when the specific cam of the same contour individually yielded. By giving an axial motion to the camshaft, allowing the follower to follow different contours, continuous variation of valve timing will be achieved.

Keywords: volumetric efficiency; continuously variable valve timing; CVVT; variable valve action; variable cam profile; IC engines; camshafts; camshaft design; vehicle design; curvilinear cam surface; cam contours; valve opening times; valve closing times; diesel engines; engine speeds; axial motion.

DOI: 10.1504/IJVD.2017.082581

International Journal of Vehicle Design, 2017 Vol.73 No.1/2/3, pp.63 - 75

Available online: 22 Feb 2017 *

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