Apparatus and method for operating a clutch in a transmission

A control module-implemented method to control a clutch in a dual clutch transmission, comprising:

• monitoring a frequency response at a single location in the transmission comprising a point of engagement between mating surfaces of the clutch and a clutch housing when the clutch is cyclically loaded during a transition from a present gear number operation to a predicted next gear number operation, comprising:
• monitoring a first amplitude indicative of a number of occurrences the response repeats one time per revolution of the clutch, said response being indicative of a peak friction value between the mating surfaces;
• monitoring a second amplitude indicative of a number of occurrences the response repeats two times per revolution of the clutch;
• and
• monitoring a third amplitude indicative of a number of occurrences the response repeats three times per revolution of the clutch;
• determining a first ratio comprising a ratio of the second amplitude to the first amplitude;
• determining a second ratio comprising a ratio of the third amplitude to the first amplitude;
• and
• during the transition from the present gear number operation to the predicted next gear number operation
• comparing the first ratio to a first threshold ratio equal to fifty percent;
• indicating a first shudder condition based upon the comparing indicating the first ratio to be greater than the first threshold ratio, wherein the first shudder condition is indicative of clutch shudder requiring remedial action that includes modifying operation of the clutch;
• if the first ratio is not greater than the first threshold ratio, comparing the first ratio and the second ratio to a second threshold ratio equal to thirty percent;
• and
• indicating a second shudder condition based upon the comparing indicating either the first or second ratio to be greater than the second threshold ratio, wherein the second shudder condition is indicative of clutch shudder requiring remedial action that includes generating a service warning indicating a need to change transmission fluid.

Apparatus to control a clutch in a transmission, comprising:

• a transmission comprising a clutch;
• a torque sensor located to monitor a torque within the transmission;
• a control module:
• monitoring a signal from the torque sensor when the clutch is cyclically loaded during engagement between mating surfaces of the clutch and a clutch housing during a transition from a present gear number operation to a predicted next gear number operation;
• determining a frequency response at a single location in the transmission comprising a point of engagement between mating surfaces of the clutch and the clutch housing based on the monitored signal of the torque sensor, comprising
• determining a first amplitude indicative of a number of occurrences a response repeats one time per revolution of the clutch, said response being indicative of a peak friction value between the mating surfaces, and
• determining at least a second amplitude indicative of a number of occurrences a response repeats more than one time per revolution of the clutch;
• determining a ratio of at least the second amplitude to the first amplitude;
• and
• during the transition from the present gear number operation to the predicted next gear number operation, determining one of:
• a first shudder condition indicative of shudder requiring modifying operation of the clutch when the ratio of at least the second amplitude to the first amplitude is at least a first threshold ratio of fifty percent;
• and
• a second shudder condition indicative of shudder requiring generating a service warning indicating a need to change transmission fluid when the ratio of at least the second amplitude to the first amplitude is less than the first threshold ratio and at least a second threshold ratio of thirty percent.