System and method for the control of shifting of vehicle automatic transmission
First Claim
1. A shift control system for a vehicle automatic transmission in which desired one of plural speed ranges is achieved by selectively changing over a state of engagement of plural engaging elements, comprising:
- an engine load sensor for detecting an opening of a throttle valve or an amount of depression of an accelerator pedal arranged to control an output of an engine connected to said automatic transmission;
detecting means for detecting, based on output of said engine load sensor, a rate of change in the opening of said throttle valve or a rate of change in said amount of depression of said accelerator pedal;
determining means for determining a state of driving of a vehicle by a fuzzy inference;
setting means for setting an optimal speed range from said plural speed ranges on a basis of results of determination by said determining means; and
controlling means for selectively controlling a state of engagement of said plural engaging elements, whereinsaid setting means is provided with means for setting as said optimal speed range a speed range lower than a current speed range when said vehicle has been determined to be running on a downhill road by said determining means, andsaid controlling means is provided with means for reducing a value of an engagement parameter relating to a change-over of said state of engagement of a desired engaging element for achieving said optimal speed range when said vehicle has been determined to be running on said downhill road and also when said detected opening of said throttle valve or said detected amount of depression of said accelerator pedal is not greater than a first predetermined value and said detected rate of change in said opening of said throttle valve or said detected rate of change in said amount of depression of said accelerator pedal is not greater than a second predetermined value.
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Accused Products
Abstract
This invention relates to a shift control system and method for a vehicle automatic transmission, in which control of a downshift on a downhill road is performed by fuzzy inference. When a vehicle has been determined to be running on a downhill road by a driving state determining device, a speed range setting device sets as an optimal speed range a speed range lower than a current speed range. In the automatic transmission, the state of engagement of a desired engaging element is changed over to achieve the optimal speed range. When the vehicle has been determined to be running on the downhill road by the driving state determining device so that the speed range lower than the current speed range has been set as the optimal speed range and also when no change has been determined in engine load by an engine load detecting device, an engagement state control device reduces engaging force to be produced upon changing over the state of engagement of a desired engaging element for achieving the optimal speed range. This makes it possible to eliminate a sense of incogruity, which would otherwise occur upon shifting to a higher speed range, while assuring a good shifting response.
42 Citations
8 Claims
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1. A shift control system for a vehicle automatic transmission in which desired one of plural speed ranges is achieved by selectively changing over a state of engagement of plural engaging elements, comprising:
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an engine load sensor for detecting an opening of a throttle valve or an amount of depression of an accelerator pedal arranged to control an output of an engine connected to said automatic transmission; detecting means for detecting, based on output of said engine load sensor, a rate of change in the opening of said throttle valve or a rate of change in said amount of depression of said accelerator pedal; determining means for determining a state of driving of a vehicle by a fuzzy inference; setting means for setting an optimal speed range from said plural speed ranges on a basis of results of determination by said determining means; and controlling means for selectively controlling a state of engagement of said plural engaging elements, wherein said setting means is provided with means for setting as said optimal speed range a speed range lower than a current speed range when said vehicle has been determined to be running on a downhill road by said determining means, and said controlling means is provided with means for reducing a value of an engagement parameter relating to a change-over of said state of engagement of a desired engaging element for achieving said optimal speed range when said vehicle has been determined to be running on said downhill road and also when said detected opening of said throttle valve or said detected amount of depression of said accelerator pedal is not greater than a first predetermined value and said detected rate of change in said opening of said throttle valve or said detected rate of change in said amount of depression of said accelerator pedal is not greater than a second predetermined value. - View Dependent Claims (2, 3, 4)
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5. A method for controlling a shift of a vehicle automatic transmission in which desired one of plural speed ranges is achieved by selectively changing over a state of engagement of plural engaging elements, comprising:
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(a) detecting an opening of a throttle valve or an amount of depression of an accelerator pedal arranged to control an output of an engine connected to said automatic transmission; (b) detecting, based on said detected opening of said throttle valve or said detected amount of depression of said accelerator pedal, a rate of change in said opening of said throttle valve or a rate of change in said amount of depression of said accelerator pedal; (c) determining a state of driving of a vehicle by a fuzzy inference; (d) setting an optimal speed range from said plural speed ranges on a basis of said determination by said step (c); and (e) selectively controlling said state of engagement of said plural engaging elements, wherein said step (d) comprises the substep of setting as said optimal speed state a speed range lower than a current speed range when said vehicle has been determined to be running on a downhill road in said step (c), and wherein said engagement state control step (e) comprises the substep of reducing a value of an engagement parameter relating to a change-over of said state of engagement of a desired engaging element for achieving said optimal speed range when said vehicle has been determined to be running on said downhill road and also when said detected opening of said throttle valve or said detected amount of depression of said accelerator pedal is not greater than a first predetermined value and said detected rate of change in said opening of said throttle valve or said detected rate of change in said amount of depression of said accelerator pedal is not greater than a second predetermined value. - View Dependent Claims (6, 7, 8)
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Specification