Hitachi ZW180, Technical Manual

Page: 54 / 374

SYSTEM / Control System
T2-1-12
Engine Torque Control
Purpose: To improve fuel consumption rate by
changing the torque curve in response to the
input signals from the work mode selector
switch, shift switch and vehicle speed sen-
sor
Operation:
1. When MC receives the signal of the selected work
mode, MC detects the shift point.
2. MC has programmed torque curves to be se-
lected in response to the combination of work
mode and speed shift. MC outputs the selection
command signal most suitable to each time to
ECM .
•
When light mode (L) is selected, torque curve 1 or
2 is used.
•
When normal mode (N) or power mode (P) is se-
lected, torque curve 1 is used.
3. ECM carries out alteration control of torque
curves in response to the input torque curve se-
lection command signal.
NOTE: In case the signal from the work mode se-
lector switch is not transmitted to MC,
backup control that the work mode is fixed
to the normal mode is made.
NOTE: In case the signal from the shift switch is
not transmitted to MC, backup control that
Torque Curve 1 is selected is made.
NOTE: Each mode switch of the work mode se-
lector switch is supplied with different volt-
ages for each from the monitor unit. When
the switch selects a mode, MC judges
which mode has been selected by the input
voltage.
NOTE: The shift switch has two switches, and the
combination of their ON varies depending
on each speed shift. The controller judges
which speed shift has been selected by the
combination of the two input signals.
Engine
Torque
Engine
Speed
1
2
Conceptual Diagram of
Engine Torque Curve