A method for controlling hydraulic line pressure of a hydraulic control system in transmission includes determining an available flow from a plurality of hydraulic pumps, determining a flow consumption of functions served by the hydraulic control system, determining an estimated hydraulic line pressure based upon the flow from the pumps and the flow consumption, determining a desired hydraulic line pressure, and controlling the hydraulic pumps based upon the desired hydraulic line pressure and the estimated hydraulic line pressure.

Method and apparatus to control hydraulic line pressure in an electro-mechanical transmission

In one embodiment, an oil pressure control apparatus includes a belt-driven continuously variable transmission, a lockup clutch provided in a torque converter, a primary regulator valve that regulates a line oil pressure that becomes a source pressure of oil pressure of various parts, and a lockup control valve that performs switching when controlling engagement/release of the lockup clutch. Control of the primary regulator valve and control of the lockup control valve are performed with a single linear solenoid valve. In this case, control of the primary regulator valve and control of the lockup control valve are performed in different ranges.

Oil pressure control apparatus

A system and method involves a machine having a power train including a continuously variable transmission (CVT) associated with a plurality of virtual gear ratios. To shift between the plurality of virtual gear ratios, the machine may include an operator input device that may be movable between a plurality of distinct positions. A first position may be associated with a neutral position in which no shifting of virtual gear ratios occurs. A second position of the operator input device may be associated with a first incremental rate for shifting between the virtual gear ratios. A third position may be associated with a second incremental rate for shifting between the virtual gear ratios which is different than the first incremental rate.

Shifting virtual gears associated with a continuously variable transmission

A transmission controller determines whether a shift is a kickdown, and when the shift is determined as the kickdown, the target line pressure is increased to a first target pressure corresponding to an input torque to a continuously variable transmission increased by the kickdown; the transmission controller then determines whether the line pressure has reached the first target pressure, and if determined that the line pressure has reached the first target pressure, the target line pressure is increased to a second target pressure higher than the first target pressure.

Continuously variable transmission and a hydraulic control method thereof

A hydraulic control device has: a modulator valve using oil pressure from a hydraulic source for adjusting a modulator pressure; driving and driven-side hydraulic actuator control valves controlling hydraulic oil from the source to driving and driven-side hydraulic actuators; a driving-side control oil pressure adjusting electromagnetic valve using the modulator pressure for outputting a control oil pressure controlling the driving-side control valve; and a driven-side control oil pressure adjusting electromagnetic valve for outputting a control oil pressure controlling the driven-side control valve, the hydraulic control device including a failsafe valve switched from a normal to a failure position based on a failure disabling electric control for the driving-side and driven-side electromagnetic valves, the modulator valve making the modulator pressure lower than a value at the normal position based on an output switching pressure generated due to switching the failsafe valve from the normal to the failure position.

Hydraulic control device of continuously variable transmission for vehicle

In a line pressure control apparatus of a belt-drive CVT, a shift is achieved by varying V-groove widths of primary and secondary pulleys by a differential pressure between primary and secondary pulley pressures, originating from line pressure. The differential pressure is created by bringing a shift actuator, such as a step motor, into a control position corresponding to a target transmission ratio. The target transmission ratio is calculated based on a theoretical transmission ratio based on engine-and-vehicle operating conditions, taking account of a hardware response delay and a disturbance. The target transmission ratio is converted into a reference-model operative position, corresponding to a reference-model number-of-steps of the shift actuator. An actual transmission ratio is converted into an actual-transmission-ratio related operative position. Line pressure is corrected in a manner so as to reduce the positional deviation between the reference-model operative position and the actual-transmission-ratio related operative position.

Iida Toshiji

Papers

Line pressure control apparatus for belt-drive continuously variable transmission