Method and apparatus for providing synchronization of low to high shifts in a transfer case
First Claim
Patent Images
1. A method of synchronizing low to high shifts in a transfer case used in an automotive vehicle having a controller area network, which passes digital data signals over a digital data bus to a transfer case control unit, said method comprising:
- initiating an actuator to move a clutch from engagement with a gear set to a predetermined neutral synchronization point;
sensing the speed of the actuator and routing the signal to the control unit;
determining the time for the clutch to reach the predetermined neutral synchronization point as a function of the sensed speed of the actuator and the known rotational distance through which the actuator must move for the clutch to reach the predetermined neutral synchronization point;
maintaining the actuation of the clutch until it has reached the predetermined neutral synchronization point;
commanding the actuator to stop when the calculated time has elapsed for the clutch to reach the predetermined neutral synchronization point;
sensing the rotational speed of the transfer case input and output shafts;
comparing the input and output shaft rotational speed signals and determining a difference value;
commanding changes in engine RPM and automatic transmission gear settings through the control area network to bring the difference value within a predetermined range; and
, completing the shift from low to high by commanding further actuation of the clutch from the predetermined neutral synchronization point to a direct torque engagement of the input and output shafts when the calculated difference in the rotational speeds of the input and output shafts is determined to fall within a set predetermined range, indicating synchronization of the shafts.
1 Assignment
0 Petitions
Accused Products
Abstract
The present invention is directed toward a method to digitally control a transfer case through a digital data bus to provide synchronized low to high shift capabilities in vehicles that employ a controller area network (CAN) system. In addition, a transfer case that can be digitally controlled in a vehicle with a controller area network (CAN) system to provide synchronized low to high shifts is also disclosed.
-
Citations
20 Claims
-
1. A method of synchronizing low to high shifts in a transfer case used in an automotive vehicle having a controller area network, which passes digital data signals over a digital data bus to a transfer case control unit, said method comprising:
-
initiating an actuator to move a clutch from engagement with a gear set to a predetermined neutral synchronization point;
sensing the speed of the actuator and routing the signal to the control unit;
determining the time for the clutch to reach the predetermined neutral synchronization point as a function of the sensed speed of the actuator and the known rotational distance through which the actuator must move for the clutch to reach the predetermined neutral synchronization point;
maintaining the actuation of the clutch until it has reached the predetermined neutral synchronization point;
commanding the actuator to stop when the calculated time has elapsed for the clutch to reach the predetermined neutral synchronization point;
sensing the rotational speed of the transfer case input and output shafts;
comparing the input and output shaft rotational speed signals and determining a difference value;
commanding changes in engine RPM and automatic transmission gear settings through the control area network to bring the difference value within a predetermined range; and
,completing the shift from low to high by commanding further actuation of the clutch from the predetermined neutral synchronization point to a direct torque engagement of the input and output shafts when the calculated difference in the rotational speeds of the input and output shafts is determined to fall within a set predetermined range, indicating synchronization of the shafts. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
-
-
11. A transfer case having a synchronized low to high shift used in an automotive vehicle having a controller area network which passes digital data signals over a digital data bus, said transfer case comprising:
-
an input shaft, an output shaft, and a gear set selectively operable to translate torque between said input and output shafts at reduced speeds;
a clutch operable to translate torque between said input and said output shafts either directly or through said gear set, an actuator having a rotational output which is operatively coupled to said clutch for moving said clutch between predetermined positions;
a control unit which calculates the speed of said actuator as it moves said clutch to a neutral position, said control unit further determining the additional time until said clutch will reach a predetermined neutral synchronization point using the speed of said actuator and the remaining rotational distance through which said actuator must move for said clutch to reach said predetermined neutral synchronization point, said control unit further operable to stop said actuator when said clutch has reached said neutral synchronization point for no longer than a predetermined time, said control unit further sensing and comparing the rotational speeds of said input and output shafts and signaling said actuator to complete the shift from low to high by moving said clutch to provide direct torque translation between said input and output shafts when the difference in the rotational speeds of said input and output shafts is less than a predetermined value; and
,said controller area network including a digital data interface to allow the transfer of digital data between said control unit and other vehicle systems. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
-
Specification