Control system for automatic transmissions of automotive vehicles

Claim 2

A control system for controlling hydraulic pressure in a hydraulic control circuit for an automotive vehicle automatic transmission, said hydraulic control circuit including means for automatically shifting gear ratios in said automatic transmission and means for manually selecting an operating range for said transmission, said transmission including clutch and brake means for determining gear ratios for said transmission, hydraulic servo means responsive to hydraulic pressure for operating said clutch and brake means, and conduit means for transmitting hydraulic fluid from said hydraulic control circuit to said servo means, said control system comprising a pump for supplying hydraulic fluid under pressure to said hydraulic control circuit, means for driving said pump, and a pump drive control circuit for controlling said pump drive means to vary the output of said pump in accordance with operation of said automatic transmission, said pump drive control circuit including means for maintaining said pump output at a lower level when no gear ratio shifting and no range shifting is occurring in said transmission, and means increasing the output of said pump to a higher level for a time period during operation of said servo means when gear ratio shifting or range shifting are occurring.

Claim 3

A system according to claim 1 wherein said means for driving said pump comprises an electric motor having an electrical circuit for controlling operation thereof, and wherein said drive control circuit includes a parallel circuit having a first resistor connected in one leg thereof and a second resistor and a transistor connected in another leg thereof, means connecting said parallel circuit in series with said electrical circuit controlling said motor, and logic circuit means responsive to operation of said automatic transmission for switching said transistor between a conductive and a non-conductive state to vary the resistance in said electrical circuit controlling said motor whereby the operating speed of said motor may be varied to increase or decrease the output of said pump in accordance with the operating state of said transmission.

Claim 4

A system according to claim 1 wherein said pump drive control circuit includes logic circuit means for applying a signal derived from automatic shifting means to said logic circuit means, means for applying a signal derived from said manual selecting means to said logic circuit means, said logic circuit means including means for coordinating said signals applied thereto and for applying a control signal representative of the operating condition of said automatic shifting means and of said manual selecting means as a control function to said pump drive means.

Claim 5

A system according to claim 3 wherein said automatic shifting means include a shift signal generator comprising means for sensing the velocity of said vehicle and for generating a signal representative thereof, means for sensing the load upon an engine powering said vehicle and for generating a signal representative thereof, and means for comparing said signals generated by said velocity and load sensing means and for applying a control signal representative of said compared signals as a control function to both said hydraulic control circuit and to said logic circuit means.

Claim 6

A system according to claim 4 wherein said transmission includes means defining a first, a second and a third gear ratio, wherein said automatic shifting means include first means for shifting said transmission between said first and said second gear ratios and second means for shifting said transmission between said second and said third gear ratios, and wherein said shift signal generator includes means for generating a pair of signals and for applying said pair of signals to said automatic shifting means, with one of said pair of signals being effective to control shifting of said transmission between said first and said second gear ratios and with the other of said pair of signals being effective to control shifting of said transmission between said second and said third gear ratios, said system further including first and second logic circuit elements formed as part of said logic circuit means, and means for applying one of said pair of signals to said first logic circuit element and the other of said pair of signals to said second logic circuit element.

Claim 7

A system according to claim 5 including switch means for generating a signal representative of the range setting of said manual selecting means, and wherein said logic circuit means include a third logic circuit element connected to receive signals from said switch means and gate means connected to receive signals from said first, said second and said third logic circuit elements to derive therefrom a resultant control signal and to apply said resultant signal as a control function to said pump driving means.

Claim 8

In an automotive vehicle powered by an internal combustion engine, a control system for controlling hydraulic pressure in a hydraulic control circuit for an automatic transmission of said vehicle, said hydraulic control circuit including electrically actuated means for controlling flow of hydraulic fluid in said hydraulic control circuit in response to electrical control signals applied thereto to effect automatic shifting of said transmission, said control system comprising: shift signal generating means for applying electrical control signals to said electrically actuated means to effect automatic shifting of said transmission in accordance with the operating conditions of said vehicle, said shift signal generating means including vehicle velocity detecting means for generating signals representative of the velocity of said vehicle, engine load detecting means for generating signals representative of the load of said internal combustion engine, and comparator means for comparing the signals emitted from said vehicle velocity detecting means and said engine load detecting means and for applying said signals to said electrically actuated means to control shifting of the gear ratios of said transmission in accordance with the operating conditions of said vehicle; range signal generating means including manual transmission range setting means for applying to said comparator means signals representative of a desired shift range setting for said transmission to control application of the control signals from said shift signal generating means to said electrically actuated means in accordance with said shift range setting; fluid pump means including electrical drive circuit means for supplying hydraulic fluid under pressure to said hydraulic control circuit; logic circuit means responsive to the control signals applied from said shift signal generating means to said electrically actuated means for applying fluid pressure control signals to said electrical drive circuit means to control the output of fluid supplied to said hydraulic control circuit by said fluid pump means; said logic circuit means including means for maintaining the output of said fluid pump means at a predetermined lower level when no transmission gear ratio shifting and no change in said shift range setting is occurring and to increase the output of said fluid pump means to a higher level during the occurrence of changes in said transmission gear ratio and in said shift range setting.

Claim 9

In an automotive vehicle powered by an internal combustion engine, a control system for controlling hydraulic pressure in a hydraulic control circuit for an automatic transmission of said vehicle, said hydraulic control circuit including electrically actuated means for controlling flow of hydraulic fluid in said hydraulic control circuit in response to electrical control signals applied thereto to effect automatic shifting of said transmission, said control system comprising: shift signal generating means for applying electrical control signals to said electrically actuated means to effect automatic shifting of said transmission in accordance with the operating conditions of said vehicle, said shift signal generating means including vehicle velocity detecting means for generating signals representative of the velocity of said vehicle, engine load detecting means for generating signals representative of the load of said internal combustion engine, and comparator means for comparing the signals emitted from said vehicle velocity detecting means and said engine load detecting means and for applying said signals to said electrically actuated means to control shifting of the gear ratios of said transmission in accordance with the operating conditions of said vehicle; range signal generating means including manual transmission range setting means for applying to said comparator means signals representative of a desired shift range setting for said transmission to control application of the control signals from said shift signal generating means to said electrically actuated means in accordance with said shift range setting; fluid pump means including electrical drive circuit means for supplying hydraulic fluid under pressure to said hydraulic control circuit; logic circuit means responsive to the control signals applied from said shift signal generating means to said electrically actuated means for applying fluid pressure control signals to said electrical drive circuit means to control the output of fluid supplied to said hydraulic control circuit by said fluid pump means; said logic circuit means including means for maintaining the output of said fluid pump means at a predetermined lower level when no transmission gear ratio shifting and no change in said shift range setting is occurring and to increase the output of said fluid pump means to a higher level during the occurrence of changes in said transmission gear ratio and in said shift range setting.