Abstract A system for controlling the hydraulic pressure of a hydraulic control circuit of an automatic, variable speed transmission during a shift operation is provided. The hydraulic control circuit includes a plurality of hydraulic pressure control valves, a plurality of flow path switching means and a plurality of solenoid valves for controlling the engagement and disengagement of clutches and brakes in the transmission. The energization of the solenoid valves disposed in the hydraulic control circuit is controlled by an electronic system, which comprises a large scale integrated semiconductor logic unit, a semiconductor read-only memory, a semiconductor read-write memory and as required, input/output ports. The semiconductor read-only memory stores, inter alia, hydraulic pressure control program data which become operative during a selected one of the shift modes, each of which comprises a combination of the current speed stage and the speed stage to be established, and which controls the hydraulic pressure of the hydraulic control circuit by a repeated deenergization and energization of the solenoid valve for a given time interval during the shift operation. A signal indicative of a shift lever position is applied to the electronic system from a shift lever detecting means. Also a signal indicative of the current vehicle speed is applied thereto from a vehicle speed signal generating means. Finally, a signal indicative of a throttle opening is applied to the system from a throttle opening detecting means. In response to these signals and based on the constants data and the program data which are stored in the read-only memory, the electronic system determines a speed stage to be established. The hydraulic pressure in the hydraulic control circuit is controlled, simultaneously with a switching of the speed stage, on the basis of the hydraulic pressure controlling program data, thus reducing any rapid fluctuation of the vehicle speed or impulses during a shift operation.
A system for controlling an automatic variable speed transmission including an hydraulic circuit having a plurality of oil pressure control valves and flow path switching means for selectively engaging or disengaging clutches and brakes of the transmission, one or more shift controlling solenoid valves and at least one pressure controlling solenoid valve, said system comprising electronic control means responsive to shift lever position, vehicle speed and throttle opening and having memory means with gear ratio change reference data for providing control signals to said solenoid valves to thereby control the operation of the transmission wherein: said electronic control means controls the hydraulic pressure in the hydraulic control circuit by performing a repeated energization and deenergization of said pressure controlling solenoid valve for a given time interval which is dependent on the shift mode during a shift operation.
Claim 2
Independent Claim
137 words
A system for controlling an automatic variable speed transmission including an hydraulic circuit having a plurality of oil pressure control valves and flow path switching means for selectively engaging or disengaging clutches and brakes of the transmission, one or more shift controlling solenoid valves and at least one pressure controlling solenoid valve, said system comprising electronic control means responsive to shift lever position, vehicle speed and throttle opening and having memory means with gear ratio change reference data for providing control signals to said solenoid valves to thereby control the operation of the transmission wherein: said electronic control means controls the hydraulic pressure in the hydraulic control circuit by performing a repeated energization and deenergization of said pressure controlling solenoid valve for a given time interval which is dependent on the shift mode during a shift operation.
Claim 3
Dependent Claim
38 words
A system as claimed in claim 1, wherein said memory means of said electronic control means stores constants data which includes "on" and "off" time data for the repeated energization and deenergization of the pressure controlling solenoid valve.
Claim 4
Dependent Claim
48 words
A system as claimed in claim 2, wherein said constants data additionally include programmed timer data which sets a limit of the given time interval and in which "on" and "off" time data is given in the form of a number of times the programmed timer is operated.
Claim 5
Dependent Claim
46 words
A system as claimed in claim 2, wherein the "on" and "off" time data which correspond to a repeated energization and deenergization of the pressure controlling solenoid valve has a different length of time at an earlier point in a time sequence than a later point.
Claim 6
Dependent Claim
49 words
A system as claimed in claim 4, wherein the constants data additionally include programmed timer data which sets a limit of the given time interval and in which the "on" and "off" time data is given in the form of a number of times the programmed timer is operated.