Automatic shift control system for automatic transmission

Claim 2

In an automatic transmission for an engine-driven vehicle having a hydraulic torque converter, a gear unit and frictionally engaging means for accomplishing the selective meshing engagement of the gears in said gear unit, an automatic shift control system comprising means for producing ratio changes by selectively actuating said frictionally engaging means, means for generating at least one electrical signal for establishing the shifting conditions including means for generating an electrical signal representing vehicle speed, at least one discriminating circuit for generating a shift signal for actuating said ratio-change producing means when the electrical signals generated by said signal generating means satisfy a predetermined condition, and at least one safEty circuit means for forcedly maintaining said gear unit in its high gear ratio when said vehicle speed exceeds a predetermined setting higher than the upshifting speed of said gear unit.

Claim 3

An automatic shift control system as claimed in claim 1 in which said safety circuit means includes means for producing a reference voltage, a second discriminating circuit having a comparator circuit for comparing the said speed representative electrical signal with said reference voltage, and a switching circuit disposed between said first mentioned discriminating circuit and said ratio-change producing means and operated by the output of said second discriminating circuit to cut off the supply of the electrical signal from said first discriminating circuit to said ratio-change producing means when said predetermined vehicle speed setting is exceeded.

Claim 4

The shift control system of claim 1 wherein said signal generating means responsive to rotational speed comprises a toothed disc of magnetic material securely mounted coaxially on the output shaft of said vehicle transmission and a coil located adjacent to the outer periphery of said toothed disc the axis of said coil being located on a line radial to said disc whereby a voltage having a frequency proportional to the rotational speed of said output shaft is induced in said coil.

Claim 5

The shift control system of claim 3 further including a digital to analog converter electrically connected between said coil and said establishing circuit.

Claim 6

The shift control system of claim 3 wherein said ratio producing and actuating means comprises a source of pressurized liquid an a hydraulic system having at least one valve for controlling the flow of liquid within said hydraulic system and at least one hydraulic operator in liquid connection with said hydraulic system and in mechanical connection with said engaging means for operating said engaging means.

Claim 7

The shift control system of claim 5 wherein said engaging means comprises at least one clutch and said hydraulic operator comprises a servo chamber mechanically adapted to cause the engagement of said clutch.

Claim 8

The shift control system of claim 5 wherein said engaging means comprises at least one brake band and said hydraulic operator comprises a servo chamber mechanically adapted to cause the engagement of said brake band.

Claim 9

The shift control system of claim 1 wherein said signal generating means is responsive to throttle position and comprises a movable contact mechanically connected with the carburetor throttle of said vehicle, a plurality of fixed contacts arranged to engage with said movable contact, each of said fixed contacts being connected through a separate resistance to a source of electrical power, and a voltage tap line connected in common between said resistances and said power source wherein the movement of said carburetor throttle causes said movable contact to engage a varying number of fixed contacts and thus to vary the output voltage on said voltage tap line proportional to the setting of said carburetor throttle.

Claim 10

The shift control system of claim 1 wherein said discriminating means comprises a comparator having first and second input leads and an output lead, and two electrical signals are generated one of said two signals being applied to said first input lead and the other of said two signals being applied to said first input lead said comparator producing an output on said output lead only when said first signal exceeds said second signal.

Claim 11

The shift control system of claim 9 further including a feedback circuit connected between said output lead of said comparator and said first input lead thereof for adding a portion of the output signal produced by said comparator to the input signal at said first input lead whereby signals on said output lead are stabilized.

Claim 12

The shift control system of claim 9 wherein said safety circuit means comprises a second comparator which is electrically identical to the first comparator and has electrically iDentical input and output leads but differs from said first comparator in that a reference signal is applied to the second input lead of said second comparator whereby said second comparator produces an output only when said reference signal exceeds said first signal, and a switching circuit to which the output lead extends which is connected to said electrical operator.

Claim 13

In a shift control system for a vehicle transmission which includes a transmission gear assembly, engaging means for effecting gear shifting engagement of said transmission gear assembly, and shifting means for operating said engaging means, the improvement comprising, signal generator means for producing electrical signals representative of the operating conditions of the vehicle, a circuit connected to the output of said signal generator means for acting upon the output signals therefrom to establish a shift condition and an electrical operator connected to the output of said establishing circuit for actuating said shifting means and safety circuit means for controlling said electrical operator and maintaining said shifting means in its high speed position when the rotational speed of the output shaft of said transmission exceeds a predetermined setting regardless of the output from said establishing circuit.

Claim 14

In a shift control system for a vehicle transmission which includes a transmission gear assembly, engaging means for effecting gear shifting engagement of said transmission gear assembly, and shifting means for operating said engaging means, the improvement comprising, signal generator means for producing electrical signals representative of the operating conditions of the vehicle, a circuit connected to the output of said signal generator means for acting upon the output signals therefrom to establish a shift condition and an electrical operator connected to the output of said establishing circuit for actuating said shifting means and safety circuit means for controlling said electrical operator and maintaining said shifting means in its high speed position when the rotational speed of the output shaft of said transmission exceeds a predetermined setting regardless of the output from said establishing circuit.

Claim 15

In an automatic transmission for an engine-driven vehicle having a hydraulic torque converter, a gear unit and frictionally engaging means for accomplishing the selective meshing engagement of the gears in said gear unit, an automatic shift control system, comprising: means for producing ratio changes by selectively actuating said frictionally engaging means, means for generating electrical signals for establishing the shifting conditions including means for generating an electrical signal responsive to the engine torque or throttle position and means for generating an electrical signal responsive to the r.p.m. of the output shaft or vehicle speed, at least one discriminating circuit for generating a shift signal for actuating said ratio-change producing means when the electrical signals generated by said signal generating means satisfy a predetermined condition, and at least one safety circuit means for disconnecting said ratio-change producing means from said discriminating circuit when the output shaft r.p.m. or vehicle speed exceeds a predetermined setting to cut off the supply of the electrical signal from said discriminating circuit to said ratio-change producing means so as thereby to forcedly maintain said frictionally engaging means in the high speed position, said safety circuit means including means for producing a reference voltage, a second discriminating circuit having a comparator circuit for comparing the electrical signal from said output shaft r.p.m. responsive signal generating means with said reference voltage, and a switching circuit disposed between said first discriminating circuit and said ratio-change producing means and operated by the output of said second discriminating circuit to cut off the supply of the electrical signal from said first discriminating circuit to said ratio-change producing means when the output shaft r.p.m. exceeds the predetermined setting.

Claim 16

In an automatic transmission for an engine-driven vehicle having a hydraulic torque converter, a gear unit and frictionally engaging means for accomplishing the selective meshing engagement of the gears in said gear unit, an automatic shift control system, comprising: means for producing ratio changes by selectively actuating said frictionally engaging means, means for generating electrical signals for establishing the shifting conditions including means for generating an electrical signal responsive to the engine torque or throttle position and means for generating an electrical signal responsive to the r.p.m. of the output shaft or vehicle speed, at least one discriminating circuit for generating a shift signal for actuating said ratio-change producing means when the electrical signals generated by said signal generating means satisfy a predetermined condition, and at least one safety circuit means for disconnecting said ratio-change producing means from said discriminating circuit when the output shaft r.p.m. or vehicle speed exceeds a predetermined setting to cut off the supply of the electrical signal from said discriminating circuit to said ratio-change producing means so as thereby to forcedly maintain said frictionally engaging means in the high speed position, said safety circuit means including means for producing a reference voltage, a second discriminating circuit having a comparator circuit for comparing the electrical signal from said output shaft r.p.m. responsive signal generating means with said reference voltage, and a switching circuit disposed between said first discriminating circuit and said ratio-change producing means and operated by the output of said second discriminating circuit to cut off the supply of the electrical signal from said first discriminating circuit to said ratio-change producing means when the output shaft r.p.m. exceeds the predetermined setting.

Claim 17

The shift control system of claim 13 wherein said signal generating means comprises a toothed disc of magnetic material securely mounted coaxially on the output shaft of said vehicle transmission and a coil located adjacent to the outer periphery of said toothed disc the axis of said coil being located on a line radial to said disc whereby a voltage having a frequency proportional to the rotational speed of said output shaft is induced in said coil, and a movable contact mechanically connected with the carburetor throttle of said vehicle, a plurality of fixed contacts arranged to engage with said movable contact each of said fixed contacts connected through a separate resistance to a source of electrical power and a voltage tap line connected in common between said resistAnces and said power source wherein the movement of the carburetor throttle causes said movable contact to engage a varying number of said contacts and thus to vary the output voltage on said voltage tap line proportional to the carburetor throttle setting.