Automatic electronic control for a power shift transmission

In a vehicle having selectable first and second modes of operation, a transmission system including a selectively lockable and unlockable torque converter with an input and output, a throttle controlled engine drivingly connected to the torque converter input, a shiftable transmission drivingly connected to the output of the torque converter and shiftable among a plurality of speed ratios to provide a variable speed transmission output and wherein direct drive and torque converter drive are provided from the engine to the transmission when the torque converter is locked and unlocked, respectively, and speed sensor means responsive to the speed of the transmission output to provide a speed signal proportional thereto, an automatic shift control comprising:

• electrically operated shifting means for shifting the transmission;
• first means for selecting either the first or second mode of operation;
• second means for sensing whether selected engine speed is above or below a predetermined speed and providing a selected speed signal indicative thereof;
• and
• electronic control means operatively associated with the first and second means and the speed sensor means for operating the shifting means to shift the transmission among a first range of speed ratios at a first set of speed signals and for unlocking the torque converter when the second mode of operation is selected by the first switch means, for operating the shifting means to shift the transmission among a second range of speed ratios at a second set of speed signals and selectively locking and unlocking the torque converter at a third set of speed signals when the first mode is selected and the selected speed signal indicates selected engine speed is below the predetermined speed, and for operating the shifting means to shift the transmission among a range of speed ratios at a corresponding set of speed signals and locking the torque converter for direct drive while the transmission is shifted among said range when the first mode is selected and the selected speed signal indicates selected engine speed is below the predetermined speed.

In a vehicle having a transmission system including a torque converter driven by a selectively variable speed engine, selectively activatable lockup means for locking and unlocking the torque converter to provide, respectively, direct drive and torque converter drive therethrough, a transmission operably connected to the torque converter, said transmission shiftable up and down among a plurality of gear ratios, selectively activatable shifting means operably associated with the transmission for shifting the transmission among the gear ratios, and a speed sensor responsive to the speed of the transmission output to provide a speed signal indicative of the speed thereof, a control comprising:

• first means for sensing whether a selected engine speed is above or below a predetermined speed and providing a first signal indicative thereof;
• and
• electronic control means operably associated with the shifting means and responsive to the first signal for operating the shifting means to shift the transmission among a first range of gear ratios at a first set of speed signals and for locking the torque converter to provide direct drive when the first signal indicates the selected engine speed is below the predetermined speed, and for operating the shifting means to shift the transmission among a second range of gear ratios at a second set of speed signals and for locking and unlocking the torque converter at a third set of speed signals when the first signal indicates the selected engine speed is above the predetermined speed.

In a transmission having a plurality of solenoid operated valves selectively activatable individually or in preselected combinations to shift the transmission up and down among a plurality of gear ratios, an electronic control comprising:

• storage means for storing first signals indicative of the valve or combination of valves required to be activated for shifting to each of the gear ratios;
• first circuit means operably associated with the solenoid operated valves for automatically sensing whether each of said solenoid operated valves is in an operable or inoperable condition;
• and
• means responsive to the first signals from said storage means and to the condition sensed by first circuit means for determining unusable gear ratios, said means responsive determining those gear ratios which require a valve which has been sensed by the first circuit means to be in an inoperable condition, and means for providing an indication of the gear ratios which are either usable or unusable.

A method of automatically shifting a multiple gear ratio transmission having a plurality of selectively activatable solenoids wherein the gear ratio of the transmission is determined by the state of the solenoids, the method including the steps of:

• deriving a speed signal indicative of the output speed of the transmission;
• selecting a gear ratio based on the speed signal;
• determining the solenoid or solenoids required to be activated for achieving the selected gear ratio;
• automatically checking the operating condition of the solenoids and identifying those gear ratios that are unusable because of one or more inoperable solenoids;
• and
• after the step of checking, activating the required solenoid or solenoids for the selected gear ratio if said ratio has not been identified as unusable or alternatively preventing an attempted shift to the selected gear ratio if said ratio is identified as unusable.

A method of activating a plurality of solenoid operated control valves of a controllable shift transmission, wherein the valves activated determine the gear ratio of the transmission, the method including the steps of:

• (a) storing an indication of the valves activated for each gear ratio;
• (b) selecting a gear ratio;
• (c) selecting the valves to be activated from the gear ratio selected and the stored indication;
• (d) initially pulsing the solenoids of the valves selected in step (c) with a pull-in voltage pulse of at least a pre-selected duration and thereafter pulsing the solenoids of the selected valves with a pulse train having a variable pulse amplitude depending on supply voltage;
• (e) detecting the voltage level of the supply voltage;
• and
• (f) varying the duty cycle of the pulse train in accordance with variations in the supply voltage level to limit power variations in the solenoids due to supply voltage fluctuations.

A method of automatically shifting a controllable shift transmission and locking and unlocking a selectively variable speed engine driven torque converter drivingly connected to the transmission, said transmission having a plurality of solenoid valves, wherein the solenoid valves actuated determine the gear ratio of the transmission, said transmission having a plurality of gear ratios, the method including the steps of:

• providing a speed signal indicative of the transmission output speed;
• storing at least first and second shift patterns defining transmission shift points corresponding to two pre-selected sets of speed signals;
• sensing whether selected engine speed is above or below a predetermined speed;
• shifting the transmission up and down among the gear ratios at the shift points defined by the first shift pattern when selected engine speed is below the predetermined speed, and at the shift points defined by the second shift pattern when selected engine speed is above the predetermined speed;
• and
• locking the torque converter for direct drive when the transmission is shifted according to the first shift pattern, and selectively locking and unlocking the torque converter when the transmission is shifted according to the second shift pattern.

A method of activating a plurality of electrically operated control valves of an engine-driven shiftable transmission, wherein the engine includes a control input for selecting a desired operating condition and wherein the valves activated determine the gear ratio of the transmission, the method including the steps of:

• providing a speed signal indicative of the transmission output speed;
• sensing a control input and providing a first or a second control signal if a first or a second operating condition, respectively, of the engine is selected;
• storing first and second sets of shift point locations, each set of shift point locations corresponding to a set of preselected speed signals;
• automatically selecting the first set of shift point locations when the first signal is sensed and the second set when the second signal is sensed;
• after the step of automatically selecting, comparing the speed signal with the shift point locations of the selected set and selecting an optimum gear ratio from the set based on the speed signal;
• storing a plurality of valve select signals, each valve select signal indicative of the valve or valves necessary to shift the transmission to a given gear ratio;
• and
• activating the valves indicated by the valve select signal for the selected gear ratio.

In a transmission having a plurality of solenoid operated valves selectively activatable to shift the transmission up and down among a plurality of gear ratios, including forward, reverse and neutral gear ratios, an electronic control comprising:

• solenoid driving circuits connected to the valve solenoids;
• gear selecting means for selecting a desired gear ratio;
• solenoid activating means connected to the solenoid driving circuits and responsive to the selected gear ratio for operating the driving circuits to power the solenoid or solenoids required to shift to said selected gear ratio;
• solenoid check circuit means for determining whether any of said required solenoid or solenoids are inoperable to shift to said selected gear ratio;
• indicator means for providing a problem mode indication when a required solenoid is determined to be inoperable;
• and
• means responsive to the problem mode indication for shifting to a preselected gear ratio, regardless of the desired gear ratio selected, and preventing an attempted shift to a gear ratio for which a required solenoid has been determined to be inoperable.