Continuously variable transmission control apparatus

Abstract

An apparatus for controlling a continuously variable transmission for use with an automotive vehicle. The transmission is operable at a variable speed ratio for transmitting a drive from its input shaft to its output shaft. A target value for the speed of rotation of the input shaft of the transmission is calculated based on the sensed vehicle operating conditions including vehicle acceleration. A correction factor per predetermined unit time is calculated based on the sensed vehicle acceleration when the sensed vehicle acceleration exceeds a threshold value with the accelerator pedal released. The correction factor is added to the target input shaft speed value to correct the target input shaft speed value in an increasing direction at intervals of the predetermined unit time. The threshold value is decreased as the vehicle speed increases. The speed ratio is controlled to bring the input shaft speed into coincidence with the corrected target value.

What is claimed is:  
     
       1. An apparatus for controlling a continuously variable transmission for use with an automotive vehicle including an accelerator pedal, the transmission having an input and output shaft, the transmission being operable at a variable speed ratio for transmitting a drive from the input shaft to the output shaft, comprising: 
       means for sensing vehicle operating conditions including vehicle acceleration and vehicle speed;  
       means for producing a released accelerator pedal indicative signal when the accelerator pedal is released;  
       means for calculating a target value for the speed of rotation of the input shaft based on the sensed vehicle operating conditions;  
       means for calculating a correction factor per predetermined unit time based on the sensed vehicle acceleration when the sensed vehicle acceleration exceeds a threshold value in the presence of the released accelerator pedal indicative signal;  
       means for adding the correction factor to the target input shaft speed value to correct the target input shaft speed value in an increasing direction at intervals of the predetermined unit time;  
       means for decreasing the threshold value as the vehicle speed increases; and  
       means for controlling the speed ratio to bring the input shaft speed into coincidence with the corrected target value.  
     
     
       2. A continuously variable transmission control apparatus as claimed in  claim 1 , further including means for setting the threshold value at a predetermined value greater than zero when the vehicle speed is equal to or higher than a first predetermined value and a predetermined value less than zero when the vehicle speed is equal to or higher than a second predetermined value, reducing the correction factor substantially to zero when the vehicle acceleration is equal to or less than a predetermined value less than the first predetermined value. 
     
     
       3. An apparatus for controlling a continuously variable transmission for use with an automotive vehicle including an accelerator pedal, the transmission having an input and output shaft, the transmission being operable at a variable speed ratio for transmitting a drive from the input shaft to the output shaft, comprising: 
       means for sensing vehicle operating conditions including vehicle acceleration and vehicle speed;  
       means for producing a released accelerator pedal indicative signal when the accelerator pedal is released;  
       means for calculating a target value for the speed of rotation of the input shaft based on the sensed vehicle operating conditions;  
       means for calculating a correction factor per predetermined unit time based on the sensed vehicle acceleration when the sensed vehicle acceleration is less than a threshold value in the presence of the released accelerator pedal indicative signal;  
       means for subtracting the correction factor from the target input shaft speed value to correct the target input shaft speed value in a decreasing direction at intervals of the predetermined unit time;  
       means for decreasing the threshold value as the vehicle speed increases; and  
       means for controlling the speed ratio to bring the input shaft speed into coincidence with the corrected, target value.  
     
     
       4. A continuously variable transmission control apparatus as claimed in  claim 3 , further including means for setting the threshold value at a predetermined value less than zero and close to zero when the vehicle speed is equal to or lower than a predetermined value. 
     
     
       5. An apparatus for controlling a continuously variable transmission for use with an automotive vehicle including an accelerator pedal, the transmission having an input and output shaft, the transmission being operable at a variable speed ratio for transmitting a drive from the input shaft to the output shaft, comprising: 
       means for sensing vehicle operating conditions including vehicle acceleration;  
       means for producing a released accelerator pedal indicative signal when the accelerator pedal is released;  
       means for producing a brake application indicative signal in response to application of braking to the vehicle;  
       means for calculating a target value for the speed of rotation of the input shaft based on the sensed vehicle operating conditions;  
       means for calculating a correction factor per predetermined unit time based on the sensed vehicle acceleration to bring the vehicle acceleration into a predetermined range in the presence of the released accelerator pedal indicative signal;  
       means for adding the correction factor to the target input shaft speed value to correct the target input shaft speed value at intervals of the predetermined unit time;  
       means for controlling the speed ratio to bring the input shaft speed into coincidence with the corrected target value; and  
       means for retaining the correction factor in the presence of the brake application indicative signal.  
     
     
       6. An apparatus for controlling a continuously variable transmission for use with an automotive vehicle including an accelerator pedal, the transmission having an input and output shaft, the transmission being operable at a variable speed ratio for transmitting a drive from the input shaft to the output shaft, comprising: 
       means for sensing vehicle operating conditions including vehicle acceleration;  
       means for sensing an operator's demand for vehicle cruising;  
       means for sensing an operator's demand for vehicle acceleration;  
       means for calculating a target value for the speed of rotation of the input shaft based on the sensed vehicle operating conditions;  
       means responsive to the sensed operator's demand for vehicle cruising for correcting the calculated target input shaft speed value to bring the vehicle acceleration into a predetermined range;  
       means responsive to the operator's demand for vehicle acceleration sensed during the target input shaft speed value correction for changing the target input shaft speed value at a predetermined rate toward the calculated target value; and  
       means for controlling the speed ratio to bring the input shaft speed into coincidence with the corrected target value.  
     
     
       7. A continuously variable transmission control apparatus as claimed in  claim 6 , wherein the means for correcting the calculated target input shaft speed value includes means for subtracting a predetermined value from the corrected target value at uniform time intervals when the corrected target value is equal to or greater than the calculated target value. 
     
     
       8. An apparatus for controlling a continuously variable transmission for use with an automotive vehicle including an accelerator pedal, the transmission having an input and output shaft, the transmission being operable at a variable speed ratio for transmitting a drive from the input shaft to the output shaft, comprising: 
       means for sensing vehicle operating conditions including vehicle acceleration;  
       means for sensing a degree to which the accelerator pedal is depressed;  
       means for calculating a target value for the speed of rotation of the input shaft based on the sensed vehicle operating conditions;  
       means for correcting the calculated target input shaft speed value to bring the vehicle acceleration into a predetermined range when the sensed degree indicates the accelerator pedal released;  
       means for changing the target input shaft speed value at a predetermined rate toward the calculated target value when the sensed degree indicate the accelerator pedal depressed during the target input shaft speed value correction; and  
       means for controlling the speed ratio to bring the input shaft speed into coincidence with the corrected target value.  
     
     
       9. A continuously variable transmission control apparatus as claimed in  claim 8 , wherein the means for correcting the calculated target input shaft speed value includes means for subtracting a predetermined value from the corrected target value at uniform time intervals when the corrected target value is equal to or greater than the calculated target value. 
     
     
       10. An apparatus for controlling a continuously variable transmission for use with an automotive vehicle including an accelerator pedal, the transmission having an input shaft and an output shaft, the transmission being operable at a variable speed ratio for transmitting a drive from the input shaft to the output shaft, comprising: 
       
         means for sensing vehicle operating conditions including vehicle speed;  
       
       
         means for calculating a target value for the speed of rotation of the input shaft based on the sensed vehicle operating conditions;  
       
       
         means for producing a released accelerator pedal indicative signal when the accelerator pedal is released;  
       
       
         means for determining a vehicle acceleration;  
       
       
         means for calculating a correction factor per predetermined unit time based on the determined vehicle acceleration when the determined vehicle acceleration exceeds a threshold value in the presence of the released accelerator pedal indicative signal;  
       
       
         means for adding the correction factor to the target input shaft speed value to correct the target input shaft speed value in an increasing direction at intervals of the predetermined unit time;  
       
       
         means for decreasing the threshold value as the vehicle speed increases; and  
       
       
         means for controlling the speed ratio to bring the input shaft speed into coincidence with the corrected target value. 
       
     
     
       11. A continuously variable transmission control apparatus as claimed in  claim 10 , further including means for setting the threshold value at a predetermined value greater than zero when the vehicle speed is equal to or higher than a first predetermined value and a predetermined value less than zero when the vehicle speed is equal to or higher than a second predetermined value, reducing the correction factor substantially to zero when the vehicle acceleration is equal to or less than a predetermined value less than the first predetermined value. 
     
     
       12. An apparatus for controlling a continuously variable transmission for use with an automotive vehicle including an accelerator pedal, the transmission having an input shaft and an output shaft, the transmission being operable at a variable speed ratio for transmitting a drive from the input shaft to the output shaft, comprising: 
       
         means for sensing vehicle operating conditions including vehicle speed;  
       
       
         means for calculating a target value for the speed of rotation of the input shaft based on the sensed vehicle operating conditions;  
       
       
         means for producing a released accelerator pedal indicative signal when the accelerator pedal is released;  
       
       
         means for determining a vehicle acceleration;  
       
       
         means for calculating a correction factor per predetermined unit time based on the determined vehicle acceleration when the determined vehicle acceleration is less than a threshold value in the presence of the released accelerator pedal indicative signal;  
       
       
         means for subtracting the correction factor from the target input shaft speed value to correct the target input shaft speed value in a decreasing direction at intervals of the predetermined time unit;  
       
       
         means for decreasing the threshold value as the vehicle speed increases; and  
       
       
         means for controlling the speed ratio to bring the input shaft speed into coincidence with the corrected target value. 
       
     
     
       13. A continuously variable transmission control apparatus as claimed in  claim 12 , further including means for setting the threshold value at a predetermined value less than zero and close to zero when the vehicle speed is equal to or lower than a predetermined value. 
     
     
       14. An apparatus for controlling a continuously variable transmission for use with an automotive vehicle including an accelerator pedal, the transmission having an input shaft and an output shaft, the transmission being operable at a variable speed ratio for transmitting a drive from the input shaft to the output shaft, comprising: 
       
         means for sensing vehicle operating conditions including vehicle speed;  
       
       
         means for calculating a target value for the speed of rotation of the input shaft based on the sensed vehicle operating conditions;  
       
       
         means for producing a released accelerator pedal indicative signal when the accelerator pedal is released;  
       
       
         means for producing a brake application indicative signal in response to application of braking to the vehicle;  
       
       
         means for determining a vehicle acceleration;  
       
       
         means for calculating a correction factor per predetermined unit time based on the determined vehicle acceleration to bring the vehicle acceleration into a predetermined range in the presence of the released accelerator pedal indicative signal;  
       
       
         means for adding the correction factor to the target input shaft speed value to correct the target input shaft speed value at intervals of the predetermined unit time;  
       
       
         means for controlling the speed ratio to bring the input shaft speed into coincidence with the corrected target value; and  
       
       
         means for retaining the correction factor in the presence of the brake application indicative signal. 
       
     
     
       15. An apparatus for controlling a continuously variable transmission for use with an automotive vehicle including an accelerator pedal, the transmission having an input shaft and an output shaft, the transmission being operable at a variable speed ratio for transmitting a drive from the input shaft to the output shaft, comprising: 
       
         means for sensing vehicle operating conditions including vehicle speed;  
       
       
         means for sensing an operator's demand for vehicle cruising;  
       
       
         means for calculating a target value for the speed of rotation of the input shaft based on the sensed vehicle operating conditions;  
       
       
         means for sensing an operator's demand for vehicle acceleration;  
       
       
         means for determining a vehicle acceleration;  
       
       
         means responsive to the sensed operator's demand for vehicle cruising for correcting the calculated target input shaft speed value to bring the vehicle acceleration into a predetermined range;  
       
       
         means responsive to the operator's demand for vehicle acceleration sensed during the target input shaft speed value correction for changing the target input shaft speed value at a predetermined rate toward the calculated target value; and  
       
       
         means for controlling the speed ratio to bring the input shaft speed into coincidence with the corrected target value. 
       
     
     
       16. A continuously variable transmission control apparatus as claimed in  claim 15 , wherein the means for correcting the calculated target input shaft speed value includes means for subtracting a predetermined value from the corrected target value at uniform time intervals when the corrected target value is equal to or greater than the calculated target value. 
     
     
       17. An apparatus for controlling a continuously variable transmission for use with an automotive vehicle including an accelerator pedal, the transmission having an input shaft and an output shaft, the transmission being operable at a variable speed ratio for transmitting a drive from the input shaft to the output shaft, said apparatus comprising: 
       
         means for sensing vehicle operating conditions including vehicle speed;  
       
       
         means for calculating a target value for the speed of rotation of the input shaft based on the sensed vehicle operating conditions;  
       
       
         means for sensing a degree to which the accelerator pedal is depressed;  
       
       
         means for determining a vehicle acceleration;  
       
       
         means for correcting the calculated target input shaft speed value to bring the vehicle acceleration into a predetermined range when the sensed degree indicates the accelerator pedal released;  
       
       
         means for changing the target input shaft speed value at a predetermined rate toward the calculated target value when the sensed degree indicate the accelerator pedal depressed during the target input shaft speed value correction; and  
       
       
         means for controlling the speed ratio to bring the input shaft speed into coincidence with the corrected target value. 
       
     
     
       18. A continuously variable transmission control apparatus as claimed in  claim 17 , wherein the means for correcting the calculated target input shaft speed value includes means for subtracting a predetermined value from the corrected target value at uniform time intervals when the corrected target value is equal to or greater than the calculated target value.