爆震控制课件.ppt

Electronic Spark Control (ESC) Vibration Based System Mechanization Integrator average (moving average of ADESC) Filtered Mean Average Deviation (MAD) Threshold Threshold Calculation and Knock Decision ADESC Knock event Multiplier High Octane Spark Table (deg before TDC) Low Octane Spark Table (deg before TDC) Scaler (0-1) moves up and down Octane Scaler (slow cell retard) If knocking is occurring, then the scaler will increase from zero to one. This will cause the system to move from using the values in the High Octane table towards using the values in the Low Octane table. MAP Breakpoint 90 kPa MAP Breakpoint 80 kPa RPM Breakpoint 2000 RPM Breakpoint 5000 Slow Cell Structure 15 cells Breakpoints are calibratible RPM Breakpoint 4000 RPM Breakpoint 3000 10 5 0 11 6 1 12 7 2 13 8 3 14 9 4 * Delphi/Confidential Delphi Dynamics Propulsion MT20 ESC Overview * Delphi/Confidential Delphi Dynamics Propulsion MT20 ESC Overview Courtesy of Shawn Han Factors Affecting Knock cylinder and head design base engine design Aging wear, carbon build-up carbon build-up hot spots start auto-ignition compression ratio higher CR increases knocking Temperature higher temperature increases knocking Humidity lower humidity increases knocking Octane higher octane decreases knocking Alcohol higher alcohol decreases knocking Supercharging (turbo) increases knocking Air-fuel ratio (altitude) leaner A/F increases knocking EGR may cause A/F imbalance between cylinders Spark plug heat range hotter increases knocking Engine load higher load increases knocking RPM lower RPM less engine noise easier to hear knocking TIP IN AF ratio goes lean. Trade off with emissions and driveability Equipment 4-channel oscilloscope with FFT checking windows, center frequency BNC cable, terminating resistors (100kΩ) listening device determine correct detection and no false detection/retard electrical toolkit co-axial (shielded) cable, soldering