SPEED RATIO CONTROL DEVICE FOR CONTINUOUSLY VARIABLE TRANSMISSION

摘要

PURPOSE:To allow a speed ratio to be positively controlled by correcting fluid flow depending on the characteristics of a flow control valve used in such a way that the relation between the deviation of an actual revolution from the target one, and the rate of change in revolution with time of either an input side or an output side revolution, is linear within an entire control range. CONSTITUTION:In a continuously variable transmission mechanism CVT, an effective diameter of a variable diameter V-shaped pulley is controlled by means of a hydraulic servo device, and fluid flow Q to the servo device is controlled by a flow control valve 30. In addition, line pressure PL in fluid passages is controlled by a pressure regulating valve 24, and both valves 30 and 24 are controlled by an electronic control device 38. And in the electronic control device 38 of this type, a comparison revolution Nin' is computed based on the deviation epsilon0 of an actual revolution Nin from a target input side revolution Nin<0> computed based on a throttle opening thetath. Then, the above said flow Q is computed in variables such as the deviation epsilon' which is the product of the deviation of Nin' from Nin and a feed back gain Kp, a speed ratio 'e', an input side revolution Nin, and a ratio of change in an output side revolution Nout.