Measuring and testing – Simulating operating condition – Marine
Reexamination Certificate
1997-09-12
2001-02-20
McCall, Eric S. (Department: 2855)
Measuring and testing
Simulating operating condition
Marine
Reexamination Certificate
active
06189376
ABSTRACT:
BACKGROUND
This invention relates to testing of electronic transfer case controllers, and more particularly, to a text fixture for use in testing electronic transfer case controllers.
Transfer cases, as is known, are used in four wheel drive vehicles to distribute power from the transmission to the four wheels. One conventional type of transfer case provides for four-wheel drive, where engine power is transferred to the front and rear axles of the vehicle, two-wheel drive, where engine power is transferred to the main driving axle of the vehicle, and neutral. Such a transfer case requires a shift mechanism to shift the transfer case between the four-wheel drive, two-wheel drive, and neutral positions.
Although mechanically actuated shift mechanisms have most commonly been used to shift such transfer cases, more recently, such transfer cases have been provided with eletro-mechanical shift mechanisms that are electronically controlled. In such an arrangement, an electronic control unit energizes a shift motor mechanism, typically consisting of a shift motor and gear train, which shifts the transfer case to the selected position (four-wheel drive, two-wheel drive or neutral).
As is known, it is desirable, sometimes necessary, to be able to test the operation of the electronic control unit without it being installed in a vehicle. However, to do so has typically required that the electronic control unit for the transfer case be connected to the eletro-mechanical shift mechanism and the eletro-mechanical shift mechanism be connected to the transfer case. The transfer case is, however, relatively large, bulky and heavy, making setting up a test stand for testing the transfer case electronic control unit a cumbersome process.
It is an objective of this invention to eliminate the disadvantages caused by using the transfer case in testing the transfer case electronic control unit by providing a device that simulates the characteristics of the transfer case needed to test the transfer case electronic control unit.
SUMMARY OF THE INVENTION
A text fixture for testing a transfer case electronic control unit according to this invention comprises an eletro-mechanical shift mechanism having an electronic input for coupling to an electronic output of the transfer case electronic control unit and an output shaft coupled to a transfer case load simulator. In a preferred embodiment, the transfer case load simulator comprises first and second oppositely wound torsion springs having identical torque characteristics coupled in opposed relation to the output shaft of the eletro-mechanical shift mechanism.
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Martin Chris
Morton Joe R.
Shock Karl W.
Yohman Rick
Chrysler Corporation
Fuller III Roland A.
McCall Eric S.
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