Machine element or mechanism – Control lever and linkage systems – Multiple controlled elements
Reexamination Certificate
1999-09-08
2001-03-06
Footland, Lenard A. (Department: 3682)
Machine element or mechanism
Control lever and linkage systems
Multiple controlled elements
Reexamination Certificate
active
06196078
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a shift system adapted to shift an automatic transmission of a passenger vehicle, and more particularly relates to an electronic modular unit adapted to attach to a casing of an existing transmission and that is adapted to shift the transmission based on electronic inputs.
Traditional automatic transmissions for passenger vehicles include an actuator rod or “D rod” that extends from the transmission and that can be rotated to different angular positions to shift the transmission between gear positions, such as park, reverse, neutral, and drive. Historically, the actuator rod is controlled by manually manipulating a shifter in the passenger compartment of the vehicle, with the shifter being operably connected to the actuator rod by a mechanical linkage, such as a telescoping Bowden cable or a rigid rod. Many vehicle manufacturers desire to change from the mechanical linkage to an electronically controlled shifting arrangement. One reason is to eliminate assembly problems associated with routing and connecting a stiff Bowden cable or rigid linkage between the shifter and the transmission. Another reason is to take advantage of wiring, which is easier to route and connect, requires less space, is more flexible, and is more forgiving of product variation. Also, wiring does not require a large passageway through the vehicle floor pan or firewall, thus reducing the noise and environmental problems (e.g., corrosion, water leaks, etc.) associated with large passageways through or holes in the floor pan or firewall. Also, more and more manufacturers are incorporating electrical components and electronically controlled systems into vehicles in order to take advantage of advancements in electronics for improved vehicle control, in order to meet customer demands and in order to achieve cost savings.
Despite the advantages of an electronic shifting system, another problem is that manufacturers have already made large investments in existing transmission designs and in the related tooling, fixturing, and manufacturing operations. It would require substantial lead time and huge new capital investments in order to redesign, tool up, and begin producing transmissions that are adapted to be shifted entirely and solely by an electronic signal. Thus, a system that is retrofittable and/or useable on or with existing transmissions is desired.
At least one manufacturer is considering using a DC motor attached to the actuator rod of an existing transmission to selectively rotate the actuator rod between gear positions. However, there are problems and disadvantages associated with using a DC motor in the harsh environment under a vehicle, since DC motors are not well suited for harsh environments since DC motors tend to be relatively complex and high warranty. For example, DC motors include brushes and rotating armature windings. Further, DC motors tend to be heavier and larger than desired, which can be problematic given today's stringent gas mileage requirements for vehicles. Further, space is always a problem, particularly with front wheel drive vehicles where both the motor and the transmission are located at a front of the vehicle. Another problem with DC motors is their relatively slow response time, their low torque per unit weight, and their relatively high current usage and requirements. Further, DC motors require a separate detent to hold them in a selected position after being moved, which results in extra parts and a more complicated assembly.
In addition to the above, vehicle manufactures are considering replacing traditional hand-operated shift levers, and instead using different driver interface modules (e.g. pushbuttons, miniaturized control levers or joysticks, and the like) for receiving driver inputs to control shifting transmissions. It is important that whatever interface module is used, the shifting system must be able to incorporate the same.
Accordingly, a simplified yet durable electronic shifting system for shifting existing transmissions is desired that solves the aforementioned problems and that has the aforementioned advantages.
SUMMARY OF THE INVENTION
In one aspect of the present invention, an apparatus includes an automatic transmission for a vehicle. The automatic transmission includes gearing movable to a plurality of different gear positions, and further includes an actuator rod operably coupled to the gearing and rotatable to selectively shift the gearing between the gear positions. A driver interface module is provided and a control unit is operably connected to the driver interface module that is programmed to generate signals to control shifting of the transmission based on inputs from the driver interface module. A stepper motor unit is mechanically attached to the actuator rod and electrically operably connected to the control unit, with the stepper motor unit being configured to selectively rotate the actuator rod to shift the transmission in response to the signals received from the control unit.
In another aspect of the present invention, an electronic transmission shift system is provided that is adapted to shift an existing automatic transmission for a vehicle, where the existing automatic transmission includes gearing movable to a plurality of different gear positions, and further includes an actuator rod connected to the gearing and rotatable to selectively shift the gearing between the gear positions. The shift system includes a control unit programmed to generate signals to control shifting of the transmission, and a stepper motor unit configured for mechanical attachment to the actuator rod and electrically connected to the control unit. The stepper motor unit is configured to selectively rotate the actuator rod to shift the transmission in response to the signals received from the control unit.
In yet another aspect of the present invention, an electronic transmission shift system is adapted to cooperate with a vehicle control unit for shifting an existing automatic transmission for a vehicle, where the existing automatic transmission includes a casing, and further includes gearing movable to a plurality of different gear positions, and still further includes an actuator rod connected to the gearing and rotatable to selectively shift the gearing between the gear positions, with the actuator rod having a male end. The control unit is programmed and configured to generate signals to control shifting of the transmission. The improvement includes a stepper motor unit having a housing, an end configured to matingly engage the male end of the actuator rod, and a stepper motor connected to the connector for moving the actuator rod selectively to the different gear positions.
These and other features, advantages, and objects of the present invention will be further understood and appreciated by those skilled in the art by reference to the following specification, claims, and appended drawings.
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DeJonge Robert A.
Wexall Stephen D.
Footland Lenard A.
Grand Haven Stamped Products
Hansen Colby
Price Heneveld Cooper DeWitt & Litton
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