Engine Management & Data Acquisition Systems

103 Pages·2008·0.5 MB·English

by  Shane Tecklenburg

Engine Management & Data
Acquisition Systems
Formula SAE Seminar
May 2004
Detroit
Engine Management Systems
Basics
Spark – Air - Fuel
4 stroke cycle
• Intake
• Compression
• Power
• Exhaust
• Requires 2 crankshaft revolutions for 1
cycle 720 degrees
Intake Phase
• Dependant on camshaft duration
• Typically starts before piston reaches TDC on
Exhaust stroke
• Typically ends well after BDC on Compression
stroke
• Represents the 1st half of the cycle
Compression Phase
• Begins when Intake Valve closes
• Typically begins about 40 degrees after
BDC
• Ends at TDC
• Represents the 1st half of the cycle
Power Phase
• Length depends on Exhaust valve opening
• Begins at TDC
• Ends typically 50 – 60 before BDC
• Represents the 2nd half of the cycle
Exhaust Phase
• Begins on Power Stroke
• Typically starts about 50 – 60 before BDC
• Ends usually 0 – 30 ATDC Intake Stroke
• Represents the 2nd half of the cycle
Overlap Phase
• Takes place as Exhaust Stroke changes to
Intake Stroke
• Duration depends on Cam Lobe
Separation Angle and Intake and exhaust
valve duration
• Can have a negative or positive effect
depending on operating conditions
Characterizing Fuel Injection
• We want to add fuel to the air in the right
proportion
• We will be matching air mass to fuel mass
on each cycle
• We need to know – Air Mass per Cycle
Sensing the Engine