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Toroidal continuously variable transmission control apparatus

  • US 6,931,316 B2
  • Filed: 05/13/2003
  • Issued: 08/16/2005
  • Est. Priority Date: 06/05/2002
  • Status: Active Grant
First Claim
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1. A toroidal continuously variable transmission control apparatus for an automotive vehicle comprising:

  • a variator unit comprising;

    (i) input and output disks coaxially arranged and opposing each other and having a common rotation axis;

    (ii) a power roller interposed between the input and output disks to transmit torque from the input disk to the output disk via a traction oil film formed between the power roller and each of the input and output disks, using a shearing force in the traction oil film; and

    (iii) a trunnion that supports a backface of the power roller so that the power roller is rotatable about a power-roller rotation axis;

    the trunnion being movable in a direction of a trunnion axis perpendicular to the common rotation axis of the input and output disks and the power-roller rotation axis to cause a tilting motion of the power roller and to continuously vary a transmission ratio;

    a ratio control hydraulic system comprising;

    (i) a hydraulic actuator producing a displacement of the trunnion in the trunnion-axis direction from an initial position at which the power-roller rotation axis intersects the common rotation axis of the input and output disks;

    (ii) a control valve hydraulically controlling operation of the hydraulic actuator;

    (iii) a ratio control actuator mechanically linked to the control valve to adjust a valve position of the control valve by changing a displacement of the ratio control actuator; and

    (iv) a mechanical feedback device compensating for a difference of a tilt angle of the power roller between forward and reverse operating modes and serving as a positive feedback device in the reverse operating mode and also serving as a negative feedback device in the forward operating mode during which a ratio-control-actuator displacement versus transmission ratio characteristic is relatively stable in comparison with the reverse operating mode; and

    a control unit comprising;

    (a) a desired transmission ratio setting section (100) setting a desired transmission ratio;

    (b) a transmission ratio detection section detecting a transmission ratio;

    (c) a normal-period ratio control section electronically feedback-controlling the transmission ratio based on a deviation of the transmission ratio from the desired transmission ratio so that the transmission ratio is brought closer to the desired transmission ratio, and generating a normal-period command signal to be input to the ratio control actuator for compensating for the deviation;

    (d) a ratio deviation compensation enabled/disabled state determination section determining whether or not the deviation can be compensated for by the normal-period ratio control section; and

    (e) an abnormal-period ratio control section generating an abnormal-period command signal to be input to the ratio control actuator to realize a ratio-control-actuator displacement capable of shifting the transmission ratio to a speed-reduction side, while keeping the trunnion out of contact with a stopper in the direction of the trunnion axis, when the ratio deviation compensation enabled/disabled state determination section determines that the deviation cannot be compensated for by the normal-period ratio control section.

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