Control systems for continuously variable ratio transmissions (CVT)
AssigneeBL Technology Limited
InventorPeter W. R. Stubbs
Life of this patent
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Abstract
A transmission incorporating a continuously variable ratio unit connected to further gearing, such that a plurality of regimes are available with synchronous shifting between regimes, is controlled such that to avoid hunting between regimes when the transmission is running at or around the synchronous ratio, regime and ratio changing beyond the synchronous ratio is inhibited until the optimum ratio for the prevailing operating conditions differs from the synchronous by a predetermined value.
Claims11
In a transmission of the type having a continuously variable ratio unit, further gearing, clutch means for operating the transmission in two regimes with synchronous shifting between the regimes, and control means for varying the transmission ratio according to a predetermined control strategy ratio in dependence on load and engine speed, the improvement comprising, means to inhibit regime changing from the synchronous ratio until the synchronous ratio differs from the predetermined control strategy ratio by at least a predetermined value.
A method of controlling a transmission of the type having a continuously variable ratio unit, further gearing, clutch means for operating the transmission in two regimes with synchronous shifting between the regimes, and control means for varying the transmission ratio according to a predetermined control strategy including shifting from one regime to the other from a synchronous ratio of the transmission, said method comprising inhibiting shifting of the transmission from the synchronous ratio to either regime until an optimum ratio of vehicle speed to engine speed deviates from the synchronous ratio by at least a predetermined value.
Dependencies are inferred from the claim text.