Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Transmission control
Reexamination Certificate
2000-07-07
2002-08-13
Arthur, Gertrude (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Transmission control
C701S051000, C701S058000, C701S062000, C701S064000, C180S170000, C180S179000
Reexamination Certificate
active
06434468
ABSTRACT:
BACKGROUND OF THE INVENTION
(a) Field of the Invention
The present invention relates to a shift control method for an automatic transmission, and more particularly, to a shift control method for an automatic transmission that prevents unnecessary shifting following the re-positioning of the accelerator pedal by the driver such that shift shock is reduced and acceleration performance improved.
(b) Description of the Related Art
Shifting is generally performed in an automatic transmission in accordance with changes in throttle valve opening. That is, throttle valve opening is varied through driver manipulation of the accelerator pedal, and such changes in throttle valve opening correspond to different locations on a shift pattern such that shifting is performed.
There are instances when the driver may depress and release (or release then again depress) the accelerator pedal during a short interval of time. With the use of the conventional shift control method, shifting is automatically performed as dictated by the shift pattern. For example, if the driver releases the accelerator pedal during upshifting, the upshift operation is completed then shifting is directly performed back into the lower speed. This greatly reduces shift feel as shock is generated with such frequent shifting over a short time interval. Also, responsiveness deteriorates in the case where, for example, the accelerator pedal is again depressed during a downshift operation.
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 shift control method for an automatic transmission that prevents unnecessary shifting following the re-positioning of the accelerator pedal such that shift shock is reduced and acceleration performance improved.
To achieve the above object, the present invention provides a shift control method for an automatic transmission comprising the steps of determining if upshift conditions are satisfied; determining if throttle valve opening is below a power on/off check line if upshift conditions are satisfied; determining, if throttle valve opening is below the power on/off check line, whether a change in throttle valve opening in a closed direction is less than a predetermined value; and preventing upshifting if the change in throttle valve opening in the closed direction is less than the predetermined value.
According to a feature of the present invention, the method further comprises the steps of establishing a hold time for each shift range and determining if the hold time has elapsed if throttle valve opening is above the power on/off check line or the change in throttle valve opening in the closed direction is greater than the predetermined value; and performing upshift control if the hold time has elapsed and preventing upshifting if the hold time has not elapsed.
According to another feature of the present invention, in the step of performing upshift control if the hold time has elapsed, a control duty is determined by adding a compensation duty to a shift duty and upshift control is performed according to the control duty.
According to yet another feature of the present invention, in the step of performing upshift control if the hold time has elapsed, four different levels of compensation duties according to each shift range and throttle valve opening are determined.
REFERENCES:
patent: 4486838 (1984-12-01), Itoh et al.
patent: 4823643 (1989-04-01), Koshizawa
patent: 5058014 (1991-10-01), Saitou et al.
patent: 5468198 (1995-11-01), Holbrook et al.
patent: 5800307 (1998-09-01), Choi
patent: 5806009 (1998-09-01), Horiguchi
patent: 6070118 (2000-05-01), Ohta et al.
Arthur Gertrude
Hyundai Motor Company
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