Transmission control apparatus for an automatic transmission

Abstract

The improved CVT control apparatus for a vehicle is disclosed. By using the CVT control apparatus, it becomes possible that the drive feeling is constant independently of a running state, the vehicle is accelerated as the driver's intention if accelerated due to the actuation of an accelerator pedal, and the run of the vehicle is performed so as to improve the fuel consumption rate if the acceleration is not required. By always calculating a correct driving torque, the transmission gear ratio is calculated to obtain the target driving torque set based on the amount of actuation of an accelerator pedal, and the obtained target driving torque is corrected by the gradient of a road obtained from the calculated driving torque. Further, the gear ratio which aims at the improvement of acceleration and the gear ratio which aims at the improvement of the rate of fuel consumption are weighted and combined with each other, and the optimum gear ratio is obtained by using fuzzy inference.

What is claimed is:  
     
         1 . A control apparatus for an automatic transmission of a vehicle including a gear ratio calculating unit for controlling the automatic transmission to transfer an output of an engine of the vehicle to driven wheels after changing the gear ratio, and calculating the gear ratio, and a speed-change control unit for controlling the gear ratio based on the result of the calculation, comprising: 
 a target driving torque generating unit for generating a value of the target driving torque based on a adaptation coefficient indicative of a running state and a vehicle speed,    a driving torque calculating unit for calculating a value of driving torque based on the adaptation coefficient, the vehicle speed and the engine speed,    a correcting unit for obtaining a correcting value for correcting the value of the target driving torque based on the value of the driving torque calculated by said driving torque calculating unit and correcting the target driving torque,    a gear-ratio-change-command unit for generating a gear-ratio-change-command based on the correction value obtained by said correcting means and commanding the change in the gear ratio,    wherein said speed-change control unit changes the gear ratio based on the gear-ratio-change-command from the gear-ratio-change-command unit.    
     
     
         2 . A control apparatus for an automatic transmission of a vehicle according to    claim 1   , wherein the value of the target driving torque is determined due to the characteristics of the target driving torque predetermined based on the adaptation coefficient and the vehicle speed.  
     
     
         3 . A control apparatus for an automatic transmission of a vehicle according to    claim 1   , wherein the adaptation coefficient is throttle opening of a throttle valve for controlling the amount of air taken into the engine of the vehicle.  
     
     
         4 . A control apparatus for an automatic transmission of a vehicle including a gear ratio calculating unit for controlling the automatic transmission to transfer an output of an engine of the vehicle to driven wheels after changing the gear ratio, and calculating the gear ratio, and a speed-change control unit for controlling the gear ratio based on the result of the calculation, comprising: 
 a road gradient calculating unit for calculating gradient of a road,    a target driving torque generating portion for generating a value of the target driving torque based on a adaptation coefficient indicative of a running state, a vehicle speed and the road gradient,    a driving torque calculating unit for calculating a value of driving torque based on the adaptation coefficient, the vehicle speed and the engine speed,    a correcting means for obtaining a correcting value for correcting the value of the target driving torque based on the value of the driving torque calculated by said driving torque calculating unit and correcting the target driving torque,    a gear-ratio-change-command means for generating a gear-ratio-change-command based on the correcting value obtained by said correcting means and commanding the change in the gear ratio,    wherein said speed-change control unit changes the gear ratio based on the gear-ratio-change-command from the gear-ratio-change-command means.    
     
     
         5 . A control apparatus for an automatic transmission of a vehicle according to    claim 4   , wherein the value of the target driving torque is determined due to the characteristics of the target driving torque predetermined based on the adaptation coefficient, the vehicle speed and the road gradient.  
     
     
         6 . A control apparatus for an automatic transmission of a vehicle according to    claim 4   , wherein the road gradient is calculated based on the vehicle speed and the value of the driving torque calculated by the driving torque calculating unit.  
     
     
         7 . A control apparatus for an automatic transmission of a vehicle including a gear ratio calculating unit for controlling the automatic transmission to transfer an output of an engine of the vehicle to driven wheels after changing the gear ratio, and calculating the gear ratio, and a speed-change control unit for controlling the gear ratio based on the result of the calculation, comprising: 
 a fuel consumption amount calculating unit for calculating the amount of fuel consumption,    a first gear-ratio-change-command unit for generating a first gear-ratio-change-command, based on the value of the fuel consumption amount calculated by the fuel consumption amount calculating unit,    a road gradient calculating unit for calculating gradient of a road,    a target driving torque generating portion for generating a value of the target driving torque based on a adaptation coefficient indicative of a running state, a vehicle speed and the road gradient,    a driving torque calculating unit for calculating a value of driving torque based on the adaptation coefficient, the vehicle speed, the engine speed and a turbine speed,    a second gear-ratio-change-command unit for correcting the target driving torque based on the value of the driving torque calculated by said driving torque calculating unit and generating a second gear-ratio-change-command,    a means for recognizing driver's intention and running environment according to the adaptation coefficient and the vehicle speed,    a fuzzy inference means for generating a third gear-ratio-change-command based on an output value of the first gear-ratio-change-command means, an output value of the second gear-ratio-change-command means, an output value of the means for recognizing driver's intention and running environment and a predetermined rule for fuzzy inference,    wherein said speed-change control unit changes the gear ratio based on the third gear-ratio-change-command generatied by the fuzzy inference means.    
     
     
         8 . A control apparatus for an automatic transmission of a vehicle according to    claim 7   , wherein the fuzzy inference is performed by weighting the first gear-ratio-change-command as compared with the second gear-ratio-change-command.  
     
     
         9 . A method of controlling an automatic transmission for a vehicle, in which gear change of the automatic transmission is changed based on conditions of speed-change setting the values of the target driving torque to vehicle speeds in which a load of an engine for the vehicle is set as a parameter, comprising the steps of: 
 changing the conditions of speed-change based on an operation mode selected from at least two modes, a mode which aims at the improvement of acceleration and a mode which aims at the improvement of fuel consumption rate,    correcting a value of a target driving torque by using a driving torque obtained based on a value indicative of a running state of the vehicle, a vehicle speed, an engine speed and an turbine speed of a torque converter for the automatic transmission,    wherein the magnitude of variation of the engine speed to variation of the engine load is set so that the magnitude in a mode which aims at the improvement of acceleration may be larger than that in a mode which aims at the improvement of fuel consumption rate at an area of a low load, and the magnitude in a mode which aims at the improvement of fuel consumption rate may be larger than that in a mode which aims at the improvement of acceleration at an area of a high load.    
     
     
         10 . A method of controlling an automatic transmission for a vehicle according to    claim 9   , further comprising the steps of : 
 inferring a adaptation coefficient based on a predetermined rule for fuzzy inference, and    changing the conditions of speed-change by using the fuzzy inference for determining the adaptation coefficient based on the extent of the increase and decrease of the inferred adaptation coefficient.    
     
     
         11 . A method of controlling an automatic transmission for a vehicle according to    claim 9   , wherein the conditions of speed-change is changed by using the fuzzy inference for inferring the extent of the increase and decrease of a adaptation coefficient and determining the adaptation coefficient based on the extent of the increase and decrease.