System structure

(Continued)

System structure

The automatic clutch system features a control unit which collects information on the status and operation of the vehicle and processes the controls to be transmitted to an electric-mechanic actuator. This device shifts the clutch disengagement lever located on the gearbox by means of an hydraulic circuit.

The system components are:

ELECTRONIC CONTROL UNIT

The control unit contains a microprocessor, a ROM (where the program resides) and external component interface circuits.

SENSORS

The automatic clutch system features some sensors which transmit the signals required by the control unit to operate correctly.

The sensors are:

• Gear lever pressure sensor (push-pull): this sensor detects the driver's intention to shift gear by means of a switch built into the gear lever;
• Potentiometer gear recognition sensors.

The purpose of these sensors is:

• to indicate the engaged gear;
• to signal the engagement/disengagement of a gear and to detect neutral.

The automatic clutch system uses a specific throttle position sensor and an engine rev signal (shared with the fuel supply system) to define the engine load.

ELECTRIC-MECHANIC ACTUATOR

Consists of:

• DC electric motor;
• Screw/nut screw reducer;
• Compensation spring which - by means of a specific movement - balances the diaphragm spring and assists the electric motor during disengagement;
• potentiometer sensor which informs the control unit on the position of the pump cylinder.

This unit transforms the electric signals from the control unit in power signals to operate the electric motor (electric-mechanic actuator).

TRADITIONAL HYDRAULIC CONTROL

Controls the movement of the disengagement lever located on the gearbox.

It consists of:

• master cylinder;
• union pipes;
• actuator cylinder;
• oil reservoir;
• solenoid valve to: engage the clutch in the event of a severe automatic clutch system fault.

ALARM AND SAFETY COMPONENTS

These devices inform the driver of incorrect or dangerous manoeuvres, faults, and failures and inhibit ignition where not allowed by the circumstances.

They are:

• warning light;
• buzzer;
• engine ignition inhibition relay.

Performance and operation

The automatic clutch system detects the exact moment when the clutch is engaged/disengaged and optimises start and end time to avoid racing.

The control unit processes the signals received from:

• the throttle potentiometer and the engine rev sensor to compute the engine load;
• the gear selection/engagement potentiometers to detect the gear in use.

The control unit compares the detected values with those mapped in its memory and defines the clutch engagement time which best suits safety and comfort parameters.

When the vehicle is still and the ignition switch is turned to OFF, the clutch is always engaged. When the ignition switch is turned to MAR and the gear is in neutral, the clutch is disengaged. If, on the other hand, a gear is engaged, the clutch is also engaged.

(Cont.)