US 4,373,619 AGranted

Transmission control system

AssigneeGrad-Line, Inc.

InventorsRenaldo F. Schritt, Martin J. Kenney

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Abstract

A control system for a shiftable multi-speed hydraulically operated transmission system. The transmission includes internal clutches which are selectively operated by the control system to effect shifting in neutral, reverse or forward speed ranges. The transmission system includes a manually operable multi-position speed range selector switch, sensing devices for ascertaining transmission input and output speeds, and other condition responsive switches. The control system includes logic circuits therein for receiving input signal information from the switches and sensing devices and for providing output signals to effect automatic shifting of the transmission to a selected speed range. The electronic controller provides operational safeguards, responds appropriately to system failures, and displays of relevant system information.

Claims8

Dependent claims

A control system for a multi-speed shiftable transmission, said transmission including a selectively operable speed range selector means for selecting a plurality of speed ranges, said plurality of speed ranges including a reverse speed range, a neutral range, and a plurality of forward speed ranges, a plurality of clutches selectively operable to provide different transmission output speed ranges, a transmission output shaft, and a torque convertor having a turbine and a lockup clutch therein, comprising:

first sensing means providing input signals indicative of a selected speed range for said transmission;
second sensing means providing input signals indicative of the actual speed range of said transmission;
third sensing means providing input signals indicative of the rotational speed of said turbine;
fourth sensing means providing input signals indicative of the rotational speed of said transmission output shaft;
means selectively actuating said plurality of clutches to shift transmission output speed ranges;
means for limiting the rotational speed of said transmission output shaft to a speed less than a predetermined speed;
means providing signals to selectively engage said lockup clutch to lock said torque convertor for direct drive;
and
control means responsive to said input signals for providing control signals to actuate said lockup clutch and said plurality of clutches according to preset conditions to effect shifting of said transmission to said selected speed range, said control means including digital computing means and encoding means for connecting said input signals to said digital computing means, and means for inhibiting shifting when said lockup clutch locks said torque convertor for direct drive and means for inhibiting shifting when said means for limiting the rotational speed of said transmission output shaft is engaged.

6 more elements

A control system for a multi-speed shiftable transmission, said transmission including a selectively operable speed range selector means for selecting a plurality of speed ranges, said plurality of speed ranges including a reverse speed range, a neutral range, and a plurality of forward speed ranges, a plurality of clutches selectively operable to provide different transmission output speed ranges, a transmission output shaft, and a torque convertor, said torque convertor having a turbine and a lockup clutch therein, comprising:

first sensing means providing input signals indicative of a selected speed range for said transmission;
second sensing means providing input signals indicative of the actual speed range of said transmission;
third sensing means providing input signals indicative of the rotational speed of said turbine;
fourth sensing means providing input signals indicative of the rotational speed of said transmission output shaft;
means selectively actuating said plurality of clutches to shift transmission output speed ranges;
means for limiting the rotational speed of said transmission output shaft to a speed less than a predetermined speed;
means providing signals to selectively engage said lockup clutch to lock said torque convertor for direct drive;
and
control means responsive to said input signals for providing control signals to actuate said lockup clutch and said plurality of clutches according to preset conditions to effect shifting of said transmission to said selected speed range, said control means including digital computing means and encoding means for connecting said input signals to said digital computing means, said encoding means including an expander for for multiplexing a plurality of signal inputs thereto into a plurality of signals for input into said digital computing means, means for inhibiting shifting when said lockup clutch locks said torque convertor for direct drive and means for inhibiting shifting when said means for limiting the rotational speed of said transmission output shaft is engaged.

6 more elements

Dependencies are inferred from the claim text.