Computer-Controlled Cam Phasing System for the Formula SAE Engine

Photo of Troves Gilbert, Emaad Ismail, Sean Persons (TL) Students: Troves Gilbert, Emaad Ismail, Sean Persons (TL)

Sponsor: The University of Texas Society of Automotive Engineers

Date: Fall 2010

Requirements:
The original scope of this project was to perform dynamometer testing at wide open throttle on the intake camshaft at various phase angles and to develop an optimized torque vs. RPM curve. This curve needs to be as flat as possible having a maximum torque at every engine speed. However, due to problems with the engine misfiring, which significantly reduced our testing range, the project team shifted its attention to other topics that ultimately have to be addressed for the implementation of a cam phasing system on the racecar. These include oil plumbing to actuate the system and analysis of the solenoid valve that controls the system.

Problem:
A previous University of Texas Formula SAE project concluded that the implementation of a cam phasing system for increased performance looked promising. Our team quantified the benefits of cam phasing and provided both control and oil plumbing designs for future implementation. We also modified the previous teams' cam phaser design to deduce the thickness dimension.

Solution:
An optimized torque vs. RPM plot was developed for engine speeds between 3,500-7,250 RPM. It was found that the phase angles of 3° retarded and 7° advanced produced torque gains up to 19% higher than the factory setting. Furthermore, since the system is hydraulically actuated, sufficient pressurized engine oil must be supplied to the actuator to function properly. Oil plumbing feasibility calculations and justifications were completed to support both our findings and concept selection. In addition, the response time of the cam phaser was investigated. It was determined that the main factor affecting the response time is the 2-way oil solenoid valve that controls oil flow to the cam phaser. Lastly, several modifications were made to the original design. The overall thickness of the entire system was reduced by .17". New exit oil passage ways were designed to allow oil to drain through its natural drainage system. A new method to connect the system to the camshaft was developed. A camshaft insert was created to retain oil within the cam phaser.

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