Page 93 - Automotive Engineering Powertrain Chassis System and Vehicle Body

Digital engine control systems CHAPTER 4.1

Fig. 4.1-11 Cylinder pressure (knocking condition).

Fig. 4.1-12 Instrumentation and waveforms for closed-loop ignition control.

sensor. This sensor responds to the acoustical energy in knock sensor is proportional to the acoustical energy in
the spectrum of the rapid cylinder pressure oscillations, the engine block at the sensor mounting point. This
as shown in Fig. 4.1-11. voltage is sent to a narrow band-pass filter that is tuned to
Fig. 4.1-12 is a diagram of the instrumentation for the knock frequency. The filter output voltage V F is
measuring knock intensity. Output voltage V E of the proportional to the amplitude of the knock oscillations,

91