Systems and methods for shifting multi-speed transmissions

A system for transmitting torque from a powerhead to a propulsor to operate a marine propulsion device, the system comprising:

• a multi-speed transmission having a first gear and a second gear each engageable to transmit the torque from the powerhead to the propulsor;
• a transmission output shaft rotatable by the first gear and by the second gear so as to transmit the torque to the propulsor;
• a transmission output shaft speed sensor operable to measure a transmission output shaft speed of the transmission output shaft;
• a shift schedule comprising a shift threshold corresponding to expected power levels for operating the marine propulsion device as a function of possible transmission output shaft speeds for the transmission output shaft;
• and
• a control system operatively coupled to the transmission output shaft speed sensor, wherein the control system is configured to:
• receive an actual power level requested for operating the marine propulsion device at a steady speed;
• receive the measured transmission output shaft speed;
• compare the actual power level to the shift threshold corresponding to the transmission output shaft speed;
• and
• control the multi-speed transmission to shift when the actual power level is outside the shift threshold.

A method for shifting a multi-speed transmission of a marine propulsion device between a first gear and a second gear each configured to transmit torque from a powerhead to a transmission output shaft, the method comprising:

• determining an actual power level requested for operating the marine propulsion device;
• determining which of the first gear and the second gear is engaged between the powerhead and the transmission output shaft;
• measuring a transmission output shaft speed at which the transmission output shaft is rotating;
• comparing, when the first gear is engaged between the powerhead and the transmission output shaft, the actual power level to one of a plurality of upshift thresholds each corresponding to expected power levels for operating the marine propulsion device as a function of the transmission output shaft speed of the transmission output shaft, the plurality of upshift thresholds being stored in an upshift schedule table;
• comparing, when the second gear is engaged between the powerhead and the transmission output shaft, the actual power level to one of a plurality of downshift thresholds each corresponding to expected power levels for operating the marine propulsion device as a function of the transmission output shaft speed of the transmission output shaft, the plurality of downshift thresholds being stored in a downshift schedule table;
• and
• controlling the multi-speed transmission to shift from the first gear to the second gear when the actual power level is less than the one of the plurality of upshift thresholds and controlling the multi-speed transmission to shift from the second gear to the first gear when the actual power level is greater than the one of the plurality of downshift thresholds.