Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Transmission control
Reexamination Certificate
2000-06-20
2001-07-17
Cuchlinski, Jr., William A. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Transmission control
C701S064000, C477S034000, C477S062000
Reexamination Certificate
active
06263274
ABSTRACT:
BACKGROUND OF THE INVENTION
(a) Field of the Invention
The present invention relates to a fail-safe control method for an automatic transmission having a one-way clutch in which, when one-way clutch roll-over occurs, shifting is performed into a second speed from a first speed after a forced downshift operation into the first speed is effected, thereby carrying out a fail-safe operation.
(b) Description of the Related Art
A one-way clutch is typically provided at two locations: between a planet carrier of a planetary gearset and a center support in a sprag configuration or on a stator of a torque converter. The one-way clutch transmits power in only one direction.
Since a long pinion of the one-way clutch of the planetary gearset rotates clockwise when in a first speed of a drive D range or a low 2 range, the counterclockwise rotation of the planet carrier of the planetary gearset is impeded such that drive power is transmitted to a ring gear of the planetary gearset. Accordingly, the planet carrier is able to rotate only clockwise and free-wheels in a clockwise direction during engine braking such that shifting into the second speed from the first speed is performed smoothly.
However, in the case where the one-way clutch of the transmission undergoes roll-over, driving in the first speed is not possible and a situation results in which engine rpm abruptly increase. In conventional vehicles, although there are systems which alert the driver that a malfunction has occurred, no internal countermeasure is taken when such a problem arises.
SUMMARY OF THE INVENTION
The present invention has been made in an effort to solve the above problems.
It is an object of the present invention to provide a fail-safe control method for an automatic transmission having a one-way clutch in which, when one-way clutch roll-over occurs, shifting is performed into a second speed from a first speed after a forced downshift operation into the first speed is effected, thereby carrying out a fail-safe operation.
To achieve the above object, the present invention provides a fail-safe control method for an automatic transmission having a one-way clutch comprising the steps of determining if shifting into a drive D range is completed; determining if synchronization into a first speed has occurred; and determining if roll-over of a one-way clutch has occurred, and if it has, controlling a friction element of a hydraulic control system so that forced shifting into the first speed is performed.
According to a feature of the present invention, the step of determining if synchronization into the first speed has occurred is performed by determining if engine rpm are greater than 450 rpm, transmission output rpm are greater than 350 rpm, and an inhibitor switch is performing input while not transmitting repeating signals, and if the inhibitor switch is performing normal output of signals, determining if a difference between a first turbine rpm when shifting into the drive D range and a second turbine rpm when a 0% duty ratio is output is greater than a predetermined value.
According to another feature of the present invention, in the step of determining if roll-over of the one-way clutch has occurred and controlling the friction element so that forced shifting into the first speed is performed, the friction element is a low-reverse brake and is controlled to a 100% duty ratio such that synchronization into the first speed occurs.
According to yet another feature of the present invention, a self-diagnostic test is performed if it is determined that synchronization into the first speed has not occurred.
According to still yet another feature of the present invention, the self-diagnostic test is performed three or more times.
According to still yet another feature of the present invention, if synchronization into the first speed is continuously not realized, it is determined that roll-over of the one-way clutch has occurred and a warning signal is output to the driver.
According to still yet another feature of the present invention, a signal to control the friction element of a 0% duty ratio is output if it is determined that shifting into the drive D range is completed.
REFERENCES:
patent: 5060158 (1991-10-01), Kono et al.
patent: 6002976 (1999-12-01), Hollstein et al.
Christie Parker & Hale LLP
Cuchlinski Jr. William A.
Hernandez Olga
Hyundai Motor Company
LandOfFree
Fail-safe control method for automatic transmission having... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Fail-safe control method for automatic transmission having..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Fail-safe control method for automatic transmission having... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2502842