Shift lever position logic
AssigneeDaimlerChrysler AG
InventorsGerald L. Holbrook, Andrew J. Harkenrider, Michael J. McNeil
Life of this patent
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Abstract
A method of determining the shift lever position of an electronic automatic transmission system by identifying the mode of transmission operation selected by the driver of the vehicle to provide hysteresis between the park, reverse, neutral, drive and low positions, to permit improved performance and response of the controller and to permit limited operation of the controller upon the occurrence or detection of a fault effecting the performance of the transmission. Such faults include the loss of a PRND2L sensor and the loss of one or more sensors indicative of the dynamics of the vehicle or hydraulic circuit.
Claims19
In a vehicle having an engine and a transmission including an input member, an output member, a gear assembly for changing the ratio of torque between said input and output members, a plurality of selectively engagable clutches for shifting said gear assembly, a plurality of sensors providing signals indicative of measurement data for predetermined conditions, a controller having memory for processing and storing the signals and predetermined values and providing signals to control said plurality of clutches, at least one PRND2L sensor sensing the position of a manually operated shift lever to select between a plurality of predetermined operating modes of said transmission such as park (P), reverse (R), neutral (N), drive (D), second (2) and low (L), and a plurality of temporary positions such as T1, T2, T3, T4 and T5 and providing a PRND2L code indicative of each of said predetermined operating mode and temporary positions, said PRND2L code having a plurality of data bits, a method of identifying a plurality of operating modes of said transmission and allowing operation of said transmission with a temporary or invalid PRND2L code utilizing signals from said plurality of sensors, said method comprising the steps of:
- generating a PRND2L code indicative of a current position of said shift lever;
- determining if said PRND2L sensor has produced invalid PRND2L codes for a time exceeding a predetermined time threshold;
- determining if said PRND2L code is valid;
- determining if hydraulic pressure above a predetermined pressure level is available;
- setting a current shift lever logic position to a previous shift lever logic position if said PRND2L sensor has not produced invalid PRND2L codes for a time exceeding said predetermined time threshold and said PRND2L code is invalid;
- otherwise, setting said current shift lever logic position based upon said previous shift lever logic position, said PRND2L code and a first predetermined schedule if said PRND2L sensor has not produced invalid PRND2L codes for a time exceeding said predetermined time threshold, said PRND2L code is not invalid and hydraulic pressure above said predetermined pressure level is not available;
- otherwise, setting said current shift lever logic position based upon said previous shift lever logic position, said PRND2L code, said signals from said plurality of sensors and a second predetermined schedule if said PRND2L sensor has not produced invalid PRND2L codes for a time exceeding said predetermined time, said PRND2L code is not invalid and hydraulic pressure above said predetermined pressure level is available;
- otherwise, setting said current shift lever logic position based upon said previous shift lever logic position, said PRND2L code and a third predetermined schedule if said PRND2L sensor has produced invalid PRND2L codes for a time exceeding said predetermined time threshold and said PRND2L code is invalid;
- otherwise, setting said current shift lever logic position based upon said previous shift lever logic position and said signals from said plurality of sensors and a fourth predetermined schedule if hydraulic pressure above said predetermined pressure level is available and said PRND2L sensor has produced invalid PRND2L codes for a time exceeding said predetermined time threshold and said PRND2L code is not invalid;
- and
- otherwise, setting said current shift lever logic position to previous shift lever logic position.
In a vehicle having an engine and a transmission including an input member, an output member, a gear assembly for changing the ratio of torque between said input and output members, a plurality of selectively engagable clutches for shifting said gear assembly, a plurality of sensors providing signals indicative of measurement data for predetermined conditions, a controller having memory for processing and storing the signals and predetermined values and providing signals to control said plurality of clutches, at least one PRND2L sensor sensing the position of a manually operated shift lever to select between a plurality of predetermined operating modes of said transmission such as park (P), reverse (R), neutral (N), drive (D), second (2) and low (L), and a plurality of temporary positions such as T1, T2, T3, T4 and T5 and providing a PRND2L code indicative of each of said predetermined operating mode and temporary positions, said PRND2L code having a plurality of data bits, a method of identifying a plurality of operating modes of said transmission and allowing operation of said transmission with a temporary or invalid PRND2L code utilizing signals from said plurality of sensors, said method comprising the steps of:
- generating a PRND2L code indicative of a current position of said shift lever;
- determining if said PRND2L sensor has produced invalid PRND2L codes for a time exceeding a predetermined time threshold;
- determining if said PRND2L code is valid;
- determining if hydraulic pressure above a predetermined pressure level is available;
- setting a current shift lever logic position to a previous shift lever logic position if said PRND2L sensor has not produced invalid PRND2L codes for a time exceeding said predetermined time threshold and said PRND2L code is invalid;
- otherwise, setting said current shift lever logic position based upon said previous shift lever logic position, said PRND2L code and a first predetermined schedule if said PRND2L sensor has not produced invalid PRND2L codes for a time exceeding said predetermined time threshold, said PRND2L code is not invalid and hydraulic pressure above said predetermined pressure level is not available;
- otherwise, setting said current shift lever logic position based upon said previous shift lever logic position, said PRND2L code, said signals from said plurality of sensors and a second predetermined schedule if said PRND2L sensor has not produced invalid PRND2L codes for a time exceeding said predetermined time, said PRND2L code is not invalid and hydraulic pressure above said predetermined pressure level is available;
- otherwise, setting said current shift lever logic position based upon said previous shift lever logic position and said signals from said plurality of sensors and said third predetermined schedule if hydraulic pressure above said predetermined pressure level is available and said PRND2L sensor has produced invalid PRND2L codes for a time exceeding said predetermined time threshold.
In a vehicle having an engine and a transmission including an input member, an output member, a gear assembly for changing the ratio of torque between said input and output members, a plurality of selectively engagable clutches for shifting said gear assembly, a plurality of sensors providing signals indicative of measurement data for predetermined conditions, a controller having memory for processing and storing the signals and predetermined values and providing signals to control said plurality of clutches, at least one PRND2L sensor sensing the position of a manually operated shift lever to select between a plurality of predetermined operating modes of said transmission such as park (P), reverse (R), neutral (N), drive (D), second (2) and low (L), and a plurality of temporary positions such as T1, T2, T3, T4 and T5 and providing a PRND2L code indicative of each of said predetermined operating mode and temporary positions, said PRND2L code having a plurality of data bits, a method of identifying a plurality of operating modes of said transmission and allowing operation of said transmission with a temporary or invalid PRND2L code utilizing signals from said plurality of sensors, said method comprising the steps of:
- generating a PRND2L code indicative of a current position of said shift lever;
- determining if said PRND2L sensor has produced invalid PRND2L codes for a time exceeding a predetermined time threshold;
- determining if said PRND2L code is valid;
- determining if hydraulic pressure above a predetermined pressure level is available;
- setting said current shift lever logic position based upon said previous shift lever logic position, said PRND2L code, said signals from said plurality of sensors and a first predetermined schedule if said PRND2L sensor has not produced invalid PRND2L codes for a time exceeding said predetermined time, said PRND2L code is not invalid and hydraulic pressure above said predetermined pressure level is available;
- otherwise, setting said current shift lever logic position based upon said previous shift lever logic position, said PRND2L code and a second predetermined schedule if said PRND2L code is not invalid and hydraulic pressure above said predetermined pressure level is not available;
- otherwise, setting said current shift lever logic position based upon said previous shift lever logic position and said signals from said plurality of sensors and a third predetermined schedule if hydraulic pressure above said predetermined pressure level is available and said PRND2L code is invalid;
- and
- otherwise, setting said current shift lever logic position to previous shift lever logic position.
Dependencies are inferred from the claim text.