Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Transmission control
Reexamination Certificate
1998-11-20
2001-04-24
Cuchlinski, Jr., William A. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Transmission control
C192S111400, C361S052000, C361S016000, C074S335000, C074S336001, C477S043000, C477S168000
Reexamination Certificate
active
06223113
ABSTRACT:
TECHNICAL FIELD
This invention relates generally to a control system for use in a transmission having electro-hydraulically actuated clutches and more particularly to a system to engage specific electro-hydraulically actuated clutches in an event of a fault condition.
BACKGROUND ART
In some machines used today, it is beneficial to keep the transmission in a predetermined gear in the event of an electrical malfunction or power failure. It is known to proportionally control the engagement of hydraulically actuated clutches by directing an electrical signal from a microprocessor to an electro-hydraulic proportional valve. Various other arrangements are known which use hydraulic valves in combination with electrically controlled solenoids to maintain fluid actuators in their engaged position in the event of an electrical system failure. Many of these known arrangements are complicated and use many different components and/or specialized components. It is desirable to provide a system that is simple in construction and effective to maintain a machine in a predetermined gear in the event there is an electrical malfunction or failure in the electrical system.
The present invention is directed to overcoming one or more of the problems as set forth above.
DISCLOSURE OF THE INVENTION
On one aspect of the present invention, in machines having electro-hydraulic transmission controls, it is desirable to ensure that in the event of an electrical malfunction or power failure the transmission responds appropriately. In the subject invention, a system is provided utilizing a transmission, which in the event of a clutch solenoid short-to-battery fault keeps the machine in a gear that utilizes a faulted clutch. If there is a short-to-ground or open circuit clutch solenoid fault then the transmission will attempt to latch the current gear or will shift to a predetermined gear that does not utilize a faulted clutch. In some cases, the selected gear may be neutral to prevent large downshifts.
In another aspect of the present invention, in machines having electro-hydraulic transmission controls, it is desirable to ensure that in the event of an electrical malfunction or power failure the transmission responds appropriately. In the subject invention, a method is provided utilizing a transmission, which in the event of a clutch solenoid short-to-battery fault keeps the machine in a gear that utilizes a faulted clutch. If there is a short-to-ground or open circuit clutch solenoid fault then the transmission will attempt to latch the current gear or will shift to a predetermined gear that does not utilize a faulted clutch. In some cases, the selected gear may be neutral to prevent large downshifts.
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McCunn Brad K.
Menke Gregory A.
Meyer Kevin G.
Caterpillar Inc.
Cuchlinski Jr. William A.
Hernandez Olga
Kercher Kevin M.
McPherson III W. Bryan
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