Planetary gear transmission systems or components – Differential planetary gearing – Bevel gear differential
Reexamination Certificate
2000-02-15
2002-03-26
Marmor, Charles A (Department: 3681)
Planetary gear transmission systems or components
Differential planetary gearing
Bevel gear differential
C475S250000, C477S098000
Reexamination Certificate
active
06361466
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention generally relates to a control for a differential lock in a vehicle drive line. More particularly, this invention relates to a temperature-based control for a differential lock.
Modern day vehicles sometimes include a differential lock that is selectively engaged for off road driving. Typically, a driver is provided with a manual switch or lever that is moved to engage the differential lock when desired. The differential lock operates in a conventional manner.
One problem associated with conventional differential lock systems is that a driver or vehicle operator may engage the differential lock and then subsequently fail to disengage the differential lock. When the differential lock is engaged over long periods of time a potential exists for damage or undesirable wear to the differential lock.
Another issue associated with differential locks is monitoring them for potential operation difficulties. If such potential difficulties can be monitored or detected, then the vehicle can be serviced rather than waiting until the differential lock fails, which requires additional expenses for completing repairs.
Accordingly, there is a need for a differential lock control system that reduces the likelihood that a differential lock is engaged while it is not necessary. Additionally, it is desirable to provide a system that can detect potential differential lock difficulties prior to a failure of the device. This invention addresses those needs and provides a system and control methodology that avoids the shortcomings and drawbacks of previous attempts.
SUMMARY OF THE INVENTION
In general terms, this invention is a control for a differential lock in a vehicle drive line. The control preferably is a temperature-based control that utilizes an operating temperature of the differential lock to determine an appropriate operating condition.
A system designed according to this invention preferably includes a manually operable switch, that is activated by a driver of the vehicle, for selectively engaging the differential lock. A temperature sensor preferably is supported near the differential lock. A controller receives input from the temperature sensor and automatically disengages the differential lock whenever the temperature detected by the sensor exceeds a chosen threshold.
In the preferred embodiment, the controller preferably is programmed to monitor fluctuations in the detected temperature and to record data indicating the temperatures over time. The controller also preferably tracks that data over time. This data can then be utilized by a service technician, for example, to determine whether the differential lock has been operated in an appropriate manner. Additionally, the data over time can provide an indication when service may be necessary, which facilitates avoiding more expensive repairs if a condition is not remedied sooner rather than later.
The various features and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the currently preferred embodiments. The drawings that accompany the detailed description can be briefly described as follows.
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patent: 4895217 (1990-01-01), Hueckler et al.
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patent: 5125490 (1992-06-01), Suzumura et al.
patent: 5301769 (1994-04-01), Weiss
patent: 5373912 (1994-12-01), Haiki et al.
patent: 5451188 (1995-09-01), Kraft et al.
patent: 6174255 (2001-01-01), Porter et al.
Carlson & Gaskey & Olds
Ho Ha
Marmor Charles A
Meritor Heavy Vehicle Systems LLC
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