Shift control system in belt-type continuously variable transmission
AssigneeJATCO Ltd
InventorsMasahiro Yamamoto, Midori Yamaguchi, Shigeki Shimanaka, Hiroyasu Tanaka, Hironobu Waki
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Abstract
When a speed of a vehicle is less than 8 km/h, an upshift determination condition is established, an idle switch signal is turned off, and a downshift is detected, an operating speed of the step motor is limited. Thereby, since the operating speed of the step motor is limited even when the vehicle is rapidly decelerated and re-accelerated before a pulley ratio is returned to a lowest value Lo, a shift speed of the downshift performed in the re-acceleration is lowered, and no slippage occurs in a V-belt between pulleys.
Claims5
A shift control system for use with a V-belt type continuously variable transmission for a vehicle in which a V-belt is wound between a primary pulley of an input side connected to an engine and a secondary pulley of an output side, a primary pulley pressure acting on the primary pulley and a secondary pulley pressure acting on the secondary pulley are generated respectively by using a line pressure as an original pressure, and a shift actuator is operated to an operating position corresponding to a target gear ratio, whereby a differential pressure is generated between the primary pulley pressure and the secondary pulley pressure to change widths of V-shaped grooves of the primary pulley and the secondary pulley so that an actual gear ratio that is obtained from speed ratio of the primary pulley and the secondary pulley becomes equal to the target gear ratio, comprising:
- shift control means for controlling the shift actuator;
- speed detecting means for detecting a speed of the vehicle;
- downshift detecting means for detecting a downshift of the belt-type continuously variable transmission, and
- idle state detecting means for detecting an idle state of the engine,
- wherein when a speed detected by the speed detecting means is less than a first predetermined speed, the downshift detecting means detects the downshift, and the idle state detecting means does not detect the idle state of the engine, the shift control means limits an operating speed of the shift actuator.
Dependencies are inferred from the claim text.