Patent ID: 6338696
Filing Date: 2002-01-15
Classification: F16H,Y10T

Abstract:
A lock-up control device for a torque converter in a vehicle, said torque converter comprising an input element connected to an engine which rotates according to a depression of an accelerator and an output element connected to an automatic transmission, said control device comprising:a sensor for detecting a depression degree of the accelerator, a sensor for detecting a throttle opening, a sensor for detecting a vehicle speed, and a microprocessor programmed to: determine whether or not the vehicle is coasting based on the depression degree of the accelerator, determine whether or not the torque converter is in a lock-up state wherein said input and output elements are directly combined, calculate an accelerator depression speed from the depression degree of the accelerator, shift the torque converter to the lock-up state when a lock-up condition holds, said lock-up condition including that the vehicle speed is in a predetermined lock-up speed range and the throttle opening is in a predetermined lock-up opening range, shift the torque converter to an unlock state, in which said input and output elements are indirectly combined, when an unlock condition holds, said unlock condition including that the accelerator is depressed at a speed larger than a predetermined speed after a state where the vehicle has been coasting at a speed within said predetermined lock-up speed range with a throttle opening within said predetermined lock-up opening range and the torque converter has been in the lock-up state, determine whether or not the vehicle speed is within a predetermined re-lock-up prevention speed range, and prevent the torque converter from shifting to the lock-up state, irrespective of the accelerator depression, as long as the vehicle speed is within the predetermined re-lock-up prevention speed range, after the torque converter has been shifted to the unlock state in said unlock condition, while allowing the torque converter to shift to the lock-up state after the torque converter has been shifted to the unlock state in a condition other than said unlock condition.