Control device for continuously variable transmission

Abstract

Disclosed is a control device for a continuously variable transmission ( 4 ) that has, as forward speed change stages, a first speed change stage ( 32 ) and a second speed change stage ( 33 ). The control device comprises a coordinated speed change means ( 12 a ) that carries out a coordinated speed changing in such a manner that when the speed change stage of an auxiliary transmission mechanism ( 30 ) is about to be changed, a speed change speed of the auxiliary transmission mechanism ( 30 ) is coordinated with a variator ( 20 ) and the variator ( 20 ) is controlled to carry out a speed change in a direction opposite to that of the auxiliary transmission mechanism ( 30 ) while carrying out the speed change operation of the auxiliary transmission mechanism ( 30 ), and a torque control means ( 12 b ) that carries out a torque regulating control during the coordinated speed changing under up-shifting by the coordinated speed change means, the torque regulating control being a control for effecting a torque-up operation to a driving source ( 1 ) after effecting a torque-down operation to the driving source and including a timing through which a starting time point of a drive force gap caused by the coordinated speed changing is advanced and a timing through which an ending time point of the drive force gap is delayed.

The invention claimed is: 
     
       1. A control device for a continuously variable transmission that comprises a continuously variable transmission mechanism that steplessly varies a rotation speed given from a driving source and an auxiliary transmission mechanism that is connected in series to the continuously variable transmission and has as forward speed change stages a first speed change stage and a second speed change stage whose speed change ratio is smaller than that of the first speed change stage,
 the control device further comprising: 
 a coordinated speed change means that carries out a coordinated speed changing in such a manner that when the speed change stage of the auxiliary transmission mechanism is about to be changed, a speed change speed of the auxiliary transmission mechanism is coordinated with the continuously variable transmission mechanism and the continuously variable transmission mechanism is controlled to carry out a speed change in a direction opposite to that of the auxiliary transmission mechanism while carrying out the speed change operation of the auxiliary transmission mechanism; and 
 a torque control means that carries out a torque regulating control during the coordinated speed changing under up-shifting by the coordinated speed change means, the torque regulating control being a control for effecting a torque-up operation to the driving source after effecting a torque-down operation to the driving source and including a timing through which a starting time point of a drive force gap caused by the coordinated speed changing is advanced and a timing through which an ending time point of the drive force gap is delayed. 
 
     
     
       2. A control device for a continuously variable transmission, as claimed in  claim 1 , in which:
 the coordinated speed change means carries out the coordinated speed changing by causing the up-shift operation to experience a preparatory phase, a torque phase, an inertia phase and an ending phase in order; and 
 the torque control means carries out the torque regulating control in a period consisting of the preparatory phase and the torque phase, and carries out the torque regulating control in a period consisting of the inertia phase and the ending phase. 
 
     
     
       3. A control device for a continuously variable transmission, as claimed in  claim 2 , in which:
 the torque control means controls a torque down amount of the driving source to take a value that is equal to or greater than 0 (zero) at the point in time when the phase is shifted from the torque phase to the inertia phase. 
 
     
     
       4. A control device for a continuously variable transmission, as claimed in  claim 2 , in which:
 the torque control means controls the torque down amount to take a value of 1 (one) at the point in time when the phase is shifted from the preparatory phase to the torque phase. 
 
     
     
       5. A control device for a continuously variable transmission, as claimed in  claim 2 , in which:
 the torque control means starts the torque regulating control at the point in time when a given time passes from the time of shifting to the inertia phase.