CONTROL FUNCTIONS (CONT’D)

Figure 10-40-3 a）Speed signal from pulser

Nrpm[min-1] = 10×fp、（fp=1/T） b）Processing of speed signal for one cylinder

・4 Cylinder Engine

Nrpm[min-1]

1 Cylinder

12pulse：4 Cylinder

・3 Cylinder Engine

12pulse：3 Cylinder

1 Cylinder

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].)

CONTROL FUNCTIONS (CONT’D)

General (Cont’d)

Rack position sensor input

The Eco-governor controls the fuel injection quantity by adjusting the rack position of the fuel injection pump. The rack position is converted into voltage by the rack position sensor, and the voltage signal is applied to E-ECU terminal RPS and sent to an AD converter. The AD converter converts the input voltage of 0 to 5 volts into an AD value of 0 to 1023. See [Figure 10-40-4].The Eco-governor controls the maximum and minimum rack positions and calculates the load factor on the basis of this AD value.

CONTROL FUNCTIONS (CONT’D)

General (Cont’d)

Coolant temperature sensor input

The input characteristics of the coolant temperature sensor are shown in [Figure 10-40-5] below. As in the case of the rack position sensor, the input voltage of 0 to 5 volts is converted into an AD value of 0 to 1023. As is clear from the figure, the thermistor resistance decreases with increasing temperatures. The measurement error of the coolant temperature sensor (129927-44900) newly adopted in the Gen2 Eco-governor is approximately ±3°C at 0°C, ±2°C at 20°C, and ±2°C at 110°C. Therefore, the conventional coolant temperature switch (121250-44901, etc.) is not featured in the Gen2 Eco-governor specification TNV as a standard coolant temperature high alarm function. The E-ECU coverts the input voltage into temperature by mapping. Connecting a thermistor with different characteristics to the sensor or connecting an unintended load to the thermistor circuit will affect the relationship between input voltage and temperature, resulting in failure to perform correct temperature measurement. Do not connect a coolant temperature sensor other than the genuine sensor to terminal RET (E16 – E28) of the E-ECU.

CONTROL FUNCTIONS (CONT’D)

General (Cont’d)

Accelerator sensor input

The Eco-governor uses the input voltage from the accelerator sensor or the input value through CAN communication to calculate the target engine speed, which is to become the standard of control (the actual engine speed is decided by the relationship between maximum engine torque and load torque, so it doesnít necessarily match the target engine speed).

The input voltage from the accelerator sensor is converted into a speed value between the low idling speed and the high idling speed. See [Figure 10-40-6]. By default, 0.7 V signal is converted into the low idling speed and 3.0V signal into the high idling speed. Input voltages corresponding to the low and high idling speeds can be adjusted in the range where the later described accelerator sensor failure cannot be detected.The input voltages can also be selected so that the gradient of the input voltage line segment between the high and low idling speed points is reversed.

See "Application interface outline" for details on accelerator sensor setting.

If the input voltage from the accelerator sensor is lower than 0.2 V or higher than 4.6 V, the E-ECU detects an accelerator sensor failure.