Automatic friction clutches and controls therefor

For a motor vehicle having an engine and a friction clutch driven by the engine, a device for actuation of the friction clutch, comprising:

• an actuation element for said clutch;
• a positioning servo drive means for moving said actuating member between a disengagement position in which the clutch is disengaged and a full engagement position in which the clutch is completely engaged and through an adjustable slippage range of engagement positions between a threshold position at the start of torque conversion and the full engagement position;
• a speed sensor means for producing a speed signal corresponding to the positioning of the engine;
• a position control means for controlling the operation of said drive means;
• a function generator means for said position control for generating a predetermined speed-position characteristic between the engine speed and the engagement position;
• characterized in:
• the position control means being arranged to adjust said actuation member in the slippage range between said threshold position and said full engagement position in response to the speed of the engine according to a characteristic set by the function generator engine means as a function of the engine speed;
• the function generating means including a first function producer responsive to the engine speed and a second function producer responsive to the gear speeds, and above a predetermined engine speed, said control means causing said drive to adjust the engagement operation of the actuating member toward the full engagement position in response to the second function producer as a function of time and independent of the engine speed responsive first function producer;
• said first and second function producers being arranged to produce correction signals superimposed on one another for determining the position of the clutch.

For a motor vehicle driven by a combustion engine an apparatus for the automatic actuation of a friction clutch comprising:

• (a) a positioning servo drive responsive means to a position control signal for adjusting the position of the friction clutch, said drive means being movable in response to said position control signal between a disengaging position in which the clutch is completely disengaged and a fully engaging position in which the clutch is completely engaged and through a slippage region of engagement positions starting at a threshold position at the beginning of torque transmission,
• (b) a speed sensor for producing a speed signal corresponding to the speed of the combustion engine,
• (c) a position control means including a control signal generator for fixing a predetermined characteristic relationship between the speed signal and the position control signal, said position control means being arranged for producing the position control signal in the slippage region between the threshold position at the beginning of torque transmission and a fully engaging position corresponding to the predetermined characteristic relationship in dependence on the speed signal, said motor vehicle including a multi-gear transmission with a first gear and a reverse gear as well as high forward gears, a motor control member, speed indicating means for producing a signal indicating vehicle operating speed, a manual switch, an engine control member, and further comprising disengagement control means for producing a first control signal upon initiation for a gear change in the multiple gear transmission;
• a second control signal when forward gears higher than the first gear are engaged;
• a third signal upon operation of said manual switch, a fourth control signal when said engine control member is in the rest position, a fifth control signal when the engine speed drops below a predetermined value;
• and a sixth control signal when the vehicle speed drops below a predetermined value;
• said disengagement control means being arranged for switching the drive means into the disengagement direction when the first control signal occurs or when the fifth control signal occurs or when the third and fourth control signals occur together or when the second and sixth control signals occur together, said first control signal, said fifth control signal, said third and fourth signals occurring together, and said second and sixth control signals occurring together, each representing a disengagement condition.

A device for automatically operating a friction clutch of a motor vehicle driven by a combustion engine and capable of moving from a disengaged position to a plurality of slippage positions and a completely engaged position, comprising:

• (a) positioning serve drive means for detecting the position of the clutch and adjusting the clutch in response to a position control signal;
• (b) rotational speed transmitter means for generating a rotational speed signal corresponding to the rotational speed of the combustion engine;
• and
• (c) position control means for forming said position control signal in response to the rotational speed signal in accordance with a preselected characteristic relationship such that for each rotational speed signal there is a unique position control signal.