US 3,938,409 A · Control system for automatic transmissions of automotive vehicles

Abstract

An hydraulic control circuit for an automotive vehicle automatic transmission includes an oil pump driven by a motor and shift valves for applying hydraulic pressures to hydraulic servos for engaging or disengaging clutches and for applying or releasing brake bands causing upshift or downshift of the transmission. The oil pump motor drive control circuit is provided with a detector for detecting traveling velocity of the vehicle, a detector for detecting the load of the vehicle engine, a range signal generator for generating a signal representative of a selected range position, a shift signal generator adapted to determine, in response to a signal from the range signal generator, a shift point and for generating a shift signal, a motor drive circuit adapted to vary the rotational speed of the motor for driving the oil pump in two stages, and a motor drive control circuit adapted to control said motor drive circuit so as to cause said motor to drive at a high speed for a time interval required for completely engaging the clutches and applying the brake bands when the upshift, downshift or shift from N or P range occur.

Claims7

Dependent claims

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.

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.

8 more elements

Dependencies are inferred from the claim text.

Control system for automatic transmissions of automotive vehicles

Life of this patent

Control system for automatic transmissions of automotive vehicles

Life of this patent

Abstract

Claims7