Hyundai Yanmar 3TNV82A-B, Manual

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CONTROL SYSTEM
TNV Application Manual 2-29
General
Speed sensor input
The Eco-governor detects the engine speed with 12 pulsers attached to the camshaft. See Figure 2-13 .
Assuming that the frequency of pulses provided by the pulsers is fp [Hz], the engine speed N rpm [min
-1
] is
given by
Nrpm[min
-1
]=(fp×2/12)×60=10×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.
The E-ECU uses a counter with a resolution of 0.125
μ
s to measure the number of pulse signals. Assuming
that the measured number of pulse signals is N and the number of cylinders is C, the actual engine speed is
given as follows:
fp[Hz]=(12÷C)/N×0.125×10
-6
)
Nrpm[min
-1
]=960×10
6
/C/N
Figure 2-13 Detection of engine speed
Cr a nk
C a m
12p u l s /rev
S peed s en s or
(m a gnetic type)
1/T
Nrpm[min -1 ]
(1) Nrpm[min -1 ] = 10×fp, (fp=1/T)
(2) 4 Cylinder Engine
1 Cylinder
( 3 ) 3 Cylinder Engine
1 Cylinder
(4) Co u nter Clock(ex: 4 Cylinder Engine)
N[p u l s e]
0.125[
μ
s ]
fp= 3 /(N×0.125e -6 )
Nrpm[min
-1 ] = 240e 6 /N
12p u l s e: 4 Cylinder
12p u l s e: 3 Cylinder
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