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Speed ratio controller and control method of continuously transmisson

  • US 6,292,730 B1
  • Filed: 06/23/1999
  • Issued: 09/18/2001
  • Est. Priority Date: 06/23/1998
  • Status: Expired due to Term
First Claim
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1. A speed ratio control device for use with a continuously variable transmission for a vehicle, said transmission transmitting an output torque of an engine to a drive wheel at an arbitrary speed ratio, said device comprising:

  • a sensor for detecting a rotation speed of said engine, a sensor for detecting an input rotation speed of said transmission, a sensor for detecting an output rotation speed of said transmission, and a microprocessor programmed to;

    control the speed ratio of said transmission within a predetermined speed ratio range based on output signals from said sensors, perform a determination if any of said sensors has an abnormality based on the output signals from said sensors, and correct said predetermined speed ratio range to be narrower when any of said sensors has been determined to have an abnormality, wherein said transmission comprises a toroidal continuously variable transmission, said control device further comprises a sensor for detecting an intake air flowrate of said engine, and said microprocessor is further programmed to calculate a fuel injection amount of said engine from said intake air flowrate and the engine rotation speed, calculate an input torque of said transmission from said fuel injection amount and said engine rotation speed, calculate a torque shift error correction value from said input torque of said transmission and a predetermined target speed ratio, apply said torque shift error correction value to control of the speed ratio of said transmission when none of said sensors has been determined to have an abnormality, and prevent said torque shift error correction value from being applied to control of the speed ratio of said transmission when any of said sensors has been determined to have abnormality.

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