Clutch Control

ECVT Clutch Control Diagram:

CLUTCH CONTROL
The clutch is applied and released and power is transmitted by controlling the current to the clutch electromagnetic coil. Signals are input to the clutch control unit and clutch current which controls starting, stopping, and switching output.

Clutch control also controls damping of the shock when the clutch is directly coupled and recoupled and when the engine brake is applied in the "Ds" position.

Safety is increased by adding a hill holder function when stopping on small grades and with a function which prevents sudden starting when the choke is used. The circuit has a self-diagnosis function and a fail-safe function.

Engine speed signal
At starting, the ignition pulse from the minus terminal of the ignition coil is detected and a clutch current proportional to the engine speed is obtained.

Accelerator switch
Operation of the accelerator pedal is detected by a microswitch attached to the accelerator pedal and, at starting, the clutch current is turned on. At stopping, this signal is used with the vehicle speed pulse to prevent the engine from stalling.

Throttle Position Switch:

Throttle-position switch
The amount the accelerator is pressed [approximately 20 mm (0.79 in) stroke] is sensed and the current required to directly couple the clutch is determined.

"D," "Ds," and "R" position switches
These switches are used to sense the "D", "Ds", and "R" positions.

Vehicle speed pulse
This pulse is built into the speedometer and is used to sense the vehicle speed and obtains a clutch current proportiona to the engine speed. This signal also controls power to the slow cut valve.

Water temperature switch
When this switch senses a "cold" engine, clutch current "rise" characteristic is changed so that the stall point is changed to the high side.

Stall point
Point at which the clutch torque curve crosses the engine full speed torque curve. Below this point, the clutch slips. Above this point, the clutch is directly coupled.

High-altitude signals (1 and 2)
A signal which varies with atmospheric pressure is emitted by the EFC control unit. This signal changes the clutch current "rise" characteristic to provide a stall point equivalent to that obtained during low-altitude operation so that the starting ability of the engine is improved at high altitudes.

Air conditioner signal
This signal senses the air conditioner operation and changes the clutch current "rise" characteristic so that the stall point is changed to the high side.