Hydraulic control method for continuously variable speed change gear mechanism for a vehicle and a drive control method for a pressure valve thereof
First Claim
1. A hydraulic control method for a continuously variable speed change gear mechanism including a pulley having a fixed pulley member fixed to a rotary shaft and a movable pulley member movable toward and away from the fixed pulley member in response to an oil pressure so that a groove width between said fixed and movable pulley members is respectively decreased and increased to thereby respectively increase and reduce the effective rotational radius of a belt extending between said fixed and movable pulley members to thus change a gear ratio and thereby control a gear change, pressure control valve means for controlling said oil pressure, and control unit means for controlling the operation of said pressure control valve means, said method including the step of causing said control unit means to switch a driving frequency of the pressure control valve means in accord with an oil temperature, said step of causing said control unit means to switch said driving frequency including the step of selectively operating said control unit in first and second modes in which it switches said driving frequency according to respective first and second schedules which are different and which each define said driving frequency as a function of said oil temperature.
2 Assignments
0 Petitions
Accused Products
Abstract
A hydraulic control method is applied to a continuously variable speed change gear mechanism including a pulley having a fixed pulley member fixed to a rotary shaft and a movable pulley member movable by oil pressure toward and away from the fixed pulley member so that a groove width between the fixed and movable pulley members is decreased or increased to thereby reduce or increase the effective rotational radius of a belt extending between the pulley members and thus change a change gear ratio and control the gear change. In this method, first to third three-way electromagnetic pressure control valves control the oil pressure and an electronic control unit (ECU) controls the electromagnetic valves, and driving frequencies of the valves are switched by the ECU in accord with the oil temperature and/or vehicle speed so that the hydraulic clutch is smoothly and effectively operated, the lifetime of the electromagnetic valves is extended, and vibration of the vehicle body due to pressure fluctuation in the hydraulic circuit is prevented.
11 Citations
17 Claims
- 1. A hydraulic control method for a continuously variable speed change gear mechanism including a pulley having a fixed pulley member fixed to a rotary shaft and a movable pulley member movable toward and away from the fixed pulley member in response to an oil pressure so that a groove width between said fixed and movable pulley members is respectively decreased and increased to thereby respectively increase and reduce the effective rotational radius of a belt extending between said fixed and movable pulley members to thus change a gear ratio and thereby control a gear change, pressure control valve means for controlling said oil pressure, and control unit means for controlling the operation of said pressure control valve means, said method including the step of causing said control unit means to switch a driving frequency of the pressure control valve means in accord with an oil temperature, said step of causing said control unit means to switch said driving frequency including the step of selectively operating said control unit in first and second modes in which it switches said driving frequency according to respective first and second schedules which are different and which each define said driving frequency as a function of said oil temperature.
- 7. A method of controlling a gear change mechanism responsive to the fluid pressure in a fluid line using electrically actuable valve means for selectively supplying a pressurized fluid to said fluid line, comprising the steps of supplying to said valve means an electrical signal at a selected frequency to control actuation of said valve means, varying a duty ratio of said electrical signal to adjust the fluid pressure within said fluid line, measuring the temperature of the fluid, and adjusting said selected frequency as a function of the measured temperature of the fluid, wherein said step of adjusting said selected frequency includes the step of setting said selected frequency to a frequency specified by a respective one of first and second schedules which are different, which are respectively utilized under first and second operational conditions which are different, and which each define said selected frequency as a function of the measured fluid temperature.
- 15. A method of controlling a gear change mechanism responsive to the fluid pressure in a fluid line using electrically actuable valve means for selectively supplying a pressurized fluid to said fluid line, comprising the steps of supplying to said valve means an electrical signal at a selected frequency to control actuation of said valve means, varying a duty ratio of said electrical signal to adjust the fluid pressure within said fluid line, measuring the temperature of the fluid, and adjusting said selected frequency in response to variation of the measured temperature of the fluid, said step of adjusting said selected frequency including the step of providing hysteresis in said selected frequency by using a first frequency value until said measured fluid temperature exceeds a first predetermined temperature and by thereafter using a second frequency value different from said first frequency value until said measured fluid temperature is below a second predetermined temperature less than said first predetermined temperature.
Specification