CONTROL FUNCTIONS (CONT’D) General Speed sensor input
Figure 10-40-3
a）Speed signal from pulser Nrpm[min-1] = 10×fp、 （fp=1/T） 1/T
Speed sensor （magnetic type）
b）Processing of speed signal for one cylinder ・4 Cylinder Engine 12pulse：4 Cylinder
Nrpm[min-1] 1 Cylinder 12puls/rev
・3 Cylinder Engine 12pulse：3 Cylinder Crank
1 Cylinder Cam
The Eco-governor detects the engine speed with 12 pulsers attached to the camshaft [Figure 10-40-3]. Assuming that the frequency of pulses provided by the pulsers is fp [Hz], the engine speed N rpm [min-1] is given by item a [Figure 10-40-3].) Nrpm [min-1] = (fp x 2/12) x 60 = 10 x fp [Hz] The engine speed fluctuates periodically due to compression and explosion strokes. As to a 4-cylinder engine, 3 pulses represent cyclic fluctuation for one cylinder. As to a 3-cylinder engine, 4 pulses represent cyclic fluctuation for one cylinder. The Eco-governor averages cyclic fluctuations for one cylinder, thus minimizing the effect of cyclic fluctuations in engine speed and ensuring stable measurement (Item b, [Figure 10-40-3].)
10-40-3 51 of 182
E55W, E60, E80 Electronic Control System Manual
