Method and system to trigger release of a safety disconnect clutch

DETAILED DESCRIPTION In FIG.
1, the course of the torque curve of a machine system over time is shown in schematic form.
The course of the torque curve M(t) is representative of the torque transferred by a specific shaft portion.
The allowable torque limit value M.
sub.
Lim is shown above the curve of the torque course M(t).
The actual torque transferred by the machine part, for instance a measurement shaft, is measured continuously, and at an arbitrary time t.
sub.
1 the transferred torque has the magnitude M.
sub.
t1.
As the course of the torque curve shows, the actual torque transferred by the shaft portion is not constant, but instead fluctuates within certain limits.
At the time t.
sub.
1 selected for purposes of explanation, the course of the torque curve is still rising, and the angle of rising slope is described by the factor dM/dt which is also detected with the measuring circuit.
If this value dM/dt is multiplied by a firmly specified time .
DELTA.
t, then at time t.
sub.
1 the comparison signal that is available is not the value M.
sub.
t1, but rather the value M, which in the present example is higher.
Since this higher value M is still below the limit value, no positioning signal is generated.
Since the measurement of the torque and the detection of the value dM/dt are done continuously, the comparison signal M is also continuously available for comparison with the specified limit value.
If at some later time an interruption in the machine system causes an overload, with a sharp rise in the torque, then a torque monitoring system of the conventional type, which allows only a simple comparison of the actual torque value with the limit value, would trigger the positioning signal that releases the clutch at time t.
sub.
2.
In the case where the torque is rising this steeply, damage to the machine system can already be occurring by this time, if the allowable limit value is set as high as possible.
However, if the measurement function M=m(t)+dM/dt.
multidot.
.
DELTA.
t is specified for the monitoring function, then the extropolation dM/dt