Method and system to trigger release of a safety disconnect clutch

System of triggering release of a safety clutch between a driving shaft portion and a driven shaft portion, particularly to isolate a drive motor (2) from a driven apparatus (3), including a release system having

• torque transducer means (9) continuously measuring torque being transferred between the driving shaft portion and the driven shaft portion, and providing a continuous torque signal (M(t));
• means (16) for furnishing a torque limit signal;
• comparator means (15) coupled to receive the limit torque signal and providing a trigger release positioning signal (17) when the limit signal is exceeded, said clutch (4) having a fixed part (5) and a movable part (6) and positioning means (7) coupled to the movable clutch part to disconnect the clutch under control of said comparator means (15) and based on said positioning signal (17)
• and comprising,
• means 11, 12, 14 generating a comparison signal, for application to the comparator means (15) for comparison with the limit signal, and for generating a signal in accordance with the relationship
• M=M(t)=dM/dt.multidot..DELTA.t
• wherein M(t) is the continuously varying torque signal, and
• .DELTA.t is the signal representative of a predetermined time interval,
• said comparison means including differentiator means (11) for continuously differentiating the torque signal (M(t)) to provide a time-derivative of the torque and generate a rate-of-torque-change siganl (dM/dt);
• means (13) for providing a signal representative of a predetermined time interval (.DELTA.t);
• multiplier means (12) coupled to receive said time interval signal (.DELTA.t) and the rate-of-torque-change signal (dM/dt) to provide a theoretical value of change in torque during said predetermined time interval;
• adder means (14) adding said theoretical change in torque during said time interval to the then existing torque, receiving said torque signal (M(t) ) and the output from said multiplier means to provide a signal representative of the theoretical value of torque based on the rate of change of the torque signal upon elapse of said predetermined time interval, said adder means being connected to control the input to the comparator means (15) for comparison with said torque limit signal;
• and coupling means (17) for controlling the positioning means (7) of the movable clutch portion (6) if the output from the comparator means indicates that the theoretical torque value signal exceeds the limit signal.