Communications: electrical – Condition responsive indicating system – Specific condition
Reexamination Certificate
1999-02-16
2001-03-20
Hofsass, Jeffery A. (Department: 2736)
Communications: electrical
Condition responsive indicating system
Specific condition
C340S683000, C340S682000, C340S440000, C340S441000, C340S438000
Reexamination Certificate
active
06204773
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus for detecting drive line system imbalances, and more particularly to a drive line vibration sensor which activates a warning when the drive line experiences a predetermined level of vibration.
A drive shaft typically includes an elongated tubular member which is operatively coupled to the transmission and axle assembly through a pair of universal joints or other similar coupling disposed on either end of the shaft. Alternatively, the drive shaft may include two or more elongated tubular members which are connected together by a universal joint or some other similar coupling device and connected between the transmission and wheel assembly.
The individual components of the drive line system discussed above often include inherent or residual imbalances due to variations in manufacturing tolerances. While steps can be taken to balance the individual components, residual imbalances often still remain. It is further known to balance the drive line system prior to, and after, installation into the vehicle. Typically, such balancing is effective to practically eliminate objectional vibration in the drive line system of a fully assembled vehicle. However, mechanical wear, residual imbalances, and road conditions may eventually lead to the disruption of the drive line balance. Vehicle drive line systems which become unbalanced are unacceptable as they produce drive line vibrations which could eventually lead to failure.
Accordingly, it is desirable to provide a vibration sensor which alerts an operator of the drive line imbalances as early as possible to prevent drive line damage from system vibration.
SUMMARY OF THE INVENTION
The vibration sensor of the present invention is preferably fabricated using micro machining technology such that the sensor is preferably fabricated as an integrated circuit chip. Accordingly, the micro machined vibration sensor can be readily located in many small inaccessible locations of a vehicle drive line. The vibration sensor of the present invention generally includes a mercury switch, a controller, and a warning device.
The mercury switch is preferably positioned such that it is minimally affected by radial acceleration yet remains sensitive to longitudinal accelerations along the longitudinal axis of a drive line. To minimize the affect of radial acceleration, the mercury switch is preferably attached to the drive line such that the mercury switch is tilted relative to the longitudinal axis such that the radial acceleration of the drive line does not activate the mercury switch. Further, the switch is positioned such that a predetermined amount of vibration, or acceleration, is necessary to activate the switch. When the switch experiences the predetermined vibration level, a circuit is completed. To further reduce the affect of radial acceleration causing false alarms, the controller is preferably programmed to communicate with the mercury switch above a predetermined radial acceleration.
In the mercury switch experiences a predetermined acceleration, the controller identifies that the mercury switch is activated and the controller activates a warning device. In the preferred embodiment, the controller awakes and activates a transmitter, such as a radio frequency (RF) transmitter which sends a signal to a remote warning device such as a warning light.
To maintain the vibration sensor in an operable state for long periods of inactivity, the transmitter is preferably maintained in a dormant state until the controller “awakens” the transmitter in response to the mercury switch activation.
REFERENCES:
patent: 4838077 (1989-06-01), Shifflet et al.
patent: 4953110 (1990-08-01), Chartrand
patent: 5033010 (1991-07-01), Lawrence et al.
patent: 5056237 (1991-10-01), Saunders
patent: 5197010 (1993-03-01), Andersson
patent: 5419192 (1995-05-01), Maxwell et al.
patent: 5561610 (1996-10-01), Schricker et al.
patent: 5621165 (1997-04-01), Miura et al.
patent: 5793649 (1998-08-01), Take et al.
Carlson & Gaskey & Olds
Hofsass Jeffery A.
Meritor Heavy Vehicle Systems LLC
Nguyen Hung
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