Apparatus to protect a clutch from overheating

An apparatus to determine friction values on a clutch and to detect an overload operating condition on such clutch disposed in an operating mechanism intermediate a motor and a drive train means, said apparatus comprising:

• (a) a means positioned on such mechanism for determining the rotational speed of such motor and for generating a first speed signal value representative of such motor rotational speed;
• (b) a means positioned on such mechanism for determining the speed of such drive train and for generating a second speed signal value representative of such drive train speed;
• (c) a slip determination means directly connected to receive said first speed signal value and said second speed signal value for determining an amount of slip in such clutch and for providing a clutch slip signal value .omega..sub.S representative of said amount of slip in such clutch;
• (d) a clutch transmitted torque determination means positioned on such operating mechanism for determining the amount of torque transmitted by such clutch and for generating a clutch transmitted torque signal value M representative of said amount of torque on such clutch;
• (e) a clutch friction value computing means connected to directly receive said clutch slip signal value .omega..sub.S and said clutch torque signal value M for computing a product of .omega..sub.S and M and for generating a product signal value representative of .omega..sub.S and M;
• (f) a memory storage means connected to receive said product signal value for assigning at least one allowable delay time and for generating an assigned delay time signal value;
• (g) a timing means connected to receive said clutch slip signal value for providing a signal value representative of current slip times, said timing means including a memory which stores slip times during periods of slip and provides a reduced current slip time during periods of no clutch slip in which said reduced current slip time during said period of no clutch slip corresponds to a cooling curve of such clutch;
• and
• (h) a comparator means connected to receive said signal value representative of said assigned delay time and said signal value representative of said current slip time for comparing said delay time with said current slip time, and providing an overload signal when said current slip time exceeds said delay time.