Shift control system for automatic transmissions

Claim 2

In an automatic transmission including a speed change gear and friction engagement unit with hydraulic servo means for accomplishing gear shifting engagements of the speed change gear and friction engagement unit, a shift control system comprising: shift valve means for changing fluid channels to selectively direct and exhaust the hydraulic pressure to said hydraulic servo means, shift point computing circuits for generating shift signals to control the fluid channel changing operations of said shift valve means, and means for delaying for a predetermined time interval the effective actual time of application of at least one of said shift signals produced by said shift point computing circuits to produce a smoother resultant gear shifting operation.

Claim 3

A shift control system according to claim 1, wherein there is further provided: a hydraulic pressure source for supplying hydraulic pressures to said hydraulic servo means, a shift range setting valve having at least a neutral position and a forward drive position for controlling fluid circuits between said hydraulic pressure source and said hydraulic servo means, vehicle engine torque responsive signal generating means, vehicle road speed responsive signal generating means, and a shift switch for detecting the forward drive position of said shift range setting valve said shift switch being connected To actuate said means for effecting predetermined time control.

Claim 4

A shift control system according to claim 2, wherein there is further provided: a pressure regulating valve for regulating the hydraulic pressure from said hydraulic pressure source to a predetermined pressure level when said hydraulic pressure is to be applied to said hydraulic servo means, a control fluid chamber in said pressure regulating valve for controlling the hydraulic pressure to be regulated to a relatively low pressure level in the presence of a controlling hydraulic pressure, and channel means for establishing a fluid connection between a channel to said hydraulic servo means used for accomplishing a high speed drive ratio in response to a preselected state of said shift valve means and said control fluid chamber in said pressure regulating valve, whereby when said shift range setting valve is moved from said neutral position to said forward drive position, said shift valve means is placed for a predetermined time in position for providing said high speed drive ratio by the action of said means for effecting predetermined time control, thereby controlling the hydraulic pressure produced by said pressure regulator valve.

Claim 5

In a vehicle automatic transmission shift control system including a speed changing gear and friction engaging unit having hydraulically controlled servo units and a source of hydraulic fluid at a normal regulated valve for effecting selective gear ratio changes in response to electrical shift point signals generated from a shift point computing circuit which is, in turn, responsive to at least one vehicle operating parameter and the position of a manual shift means having at least positions corresponding to a neutral and a forward drive condition, an improvement comprising: first means for detecting when said manual shift means is changed from the neutral to the forward drive condition, and second means connected to said source of hydraulic pressure fluid and to said first means, said second means being actuated by said first means for providing a lower pressure than said normal regulated hydraulic line pressure from said source for a predetermined time period immediately after actuation thereby relieving the degree of shock encountered when changing the transmission from a neutral to a driving status and thereafter providing said normal regulated hydraulic line pressure.

Claim 6

In a vehicle automatic transmission shift control system including a speed changing gear and friction engaging unit having hydraulically controlled servo units and a source of hydraulic fluid at a normal regulated valve for effecting selective gear ratio changes in response to electrical shift point signals generated from a shift point computing circuit which is, in turn, responsive to at least one vehicle operating parameter and the position of a manual shift means having at least positions corresponding to a neutral and a forward drive condition, an improvement comprising: first means for detecting when said manual shift means is changed from the neutral to the forward drive condition, and second means connected to said source of hydraulic pressure fluid and to said first means, said second means being actuated by said first means for providing a lower pressure than said normal regulated hydraulic line pressure from said source for a predetermined time period immediately after actuation thereby relieving the degree of shock encountered when changing the transmission from a neutral to a driving status and thereafter providing said normal regulated hydraulic line pressure.

Claim 7

An improvement as in claim 4 wherein said second means comprises a time delay means connected between said shift point computing circuit and said speed changing gear and friction engaging unit whereby, when actuated by said first means, at least one shift point signal is effectively blocked for a predetermined time period.

Claim 8

An improvement as in claim 4 wherein: the speed changing gear and friction engaging unit is normally biased to a relatively high speed ratio status and where a change from neutral to a forward drive condition in said manual shift means results in activation of an electromagnetically operated valve to change the status to a first low forward driving speed ratio, fluid control means are provided for reducing the normal regulated pressure valve of said source of hydraulic fluid when said relatively high speed ratio status exists, and said second means effectively delays the eventual change to said first low forward driving speed ratio status for an initial predetermined time period.

Claim 9

In a vehicle transmission providing at least low and high forward torque transmitting outputs, and having manually operable means for operating said transmission, a shift control system comprising: means for providing a first electrical signal which varies as a function of throttle position, means for providing a second electrical signal when said manually operable means is in a position associated with forward torque, control circuit means for providing an electrical output signal causing said transmission to be shifted between sTates providing said low and high forward torque outputs as a function of engine operating conditions, and logic means for receiving said first and second signals and causing said control circuit means to shift to a state other than the state providing said high torque output for a predetermined time before shifting to said high torque output when said second signal indicates said manually operable means has just been shifted to a position associated with forward torque and said first signal indicates the throttle setting is below a predetermined value so as to relieve the transmission shock resulting from shifting to a forward position at a low throttle position.

Claim 10

In a vehicle transmission providing at least low and high forward torque transmitting outputs, and having manually operable means for operating said transmission, a shift control system comprising: means for providing a first electrical signal which varies as a function of throttle position, means for providing a second electrical signal when said manually operable means is in a position associated with forward torque, control circuit means for providing an electrical output signal causing said transmission to be shifted between sTates providing said low and high forward torque outputs as a function of engine operating conditions, and logic means for receiving said first and second signals and causing said control circuit means to shift to a state other than the state providing said high torque output for a predetermined time before shifting to said high torque output when said second signal indicates said manually operable means has just been shifted to a position associated with forward torque and said first signal indicates the throttle setting is below a predetermined value so as to relieve the transmission shock resulting from shifting to a forward position at a low throttle position.

Claim 11

A system as in claim 7 wherein said transmission is automatic and includes low, intermediate and high torque transmitting outputs, wherein said control circuit means includes a first shift point computer for providing an electrical signal causing shifting between states providing said high and intermediate torque outputs and a second shift point computer for providing an electrical signal causing shifting between states providing said intermediate and low torque outputs and wherein said logic means includes means for delaying for a predetermined time interval operation of said second computer when said second signal indicates said manually operable means has just been shifted to a position associated with forward torque and said first signal indicates the throttle setting is below a predetermined value so that said transmission is shifted to a state providing said intermediate torque during said predetermined time interval and to said state providing said high torque following said predetermined time interval.

Claim 12

A system as in claim 8 wherein said transmission includes a hydraulic system for effecting shifting including a first solenoid which is actuated by said first computer and a second solenoid which is actuated by said second computer and wherein said delaying means include means connected between said second computer and said second solenoid for temporarily preventing said second computer for operating said second solenoid.