Measuring and testing – Liquid level or depth gauge – Float
Reexamination Certificate
1998-12-31
2001-04-03
Larkin, Daniel S. (Department: 2856)
Measuring and testing
Liquid level or depth gauge
Float
C073S313000, C338S033000
Reexamination Certificate
active
06209392
ABSTRACT:
BACKGROUND OF THE INVENTION
Fuel level sensors are known for detecting the fuel level in gasoline tanks of automobiles, which include an arm having a buoyant member at the end. The arm is pivotally mounted to a frame assembly and at the end of the arm opposite the buoyant member is a contact member. Mounted below the contact member is a ceramic resistor card. The ceramic resistor card includes multiple traces that typically extend out like the spokes of a wheel in an arc that is approximately 120°. As the level of the fuel changes, the buoyant member moves up and down and causes the arm to which it is attached to change its angle and therefore move the contact along the arc shaped conductive traces of the ceramic resistor card, which then sends a signal to the fuel level indicator. Due to the simplified nature of the arm having the direct motion imparted to the ceramic resistor card, the card must be formed on a large scale with the circuit traces best being formed in an arc. The ceramic resistor card having resistors associated therewith is generally the most expensive component of the fuel level sensor. Therefore, it would be advantageous to provide for a fuel level sensor that has a smaller ceramic resistor card. A fuel level sensor that is orientated and assembled in a different manner would allow for the ceramic resistor card to be greatly reduced in size and therefore reduce the cost of this sensor.
Therefore, it is an object of the present invention to provide for a fuel level sensor having a miniaturized ceramic resistor card. It is another object of the present invention to provide for a fuel level sensor that does not require the ceramic resistor card to be best formed with conductive traces in an arc shape.
It is a further object of the present invention to provide for a fuel level sensor having a cam attached at the pivot end of the fuel level sensor arm in order to transform the arcing motion of the arm to a linear motion.
SUMMARY OF THE INVENTION
A fuel level sensor is provided having an arm pivotally mounted to a frame. A buoyant member is mounted at a first end of the arm. A cam member is mounted at the second end of the arm adjacent a pivot point for the arm. A cam member engages a contact arm that moves linearly. A contact finger is attached to the contact arm and makes contact to a ceramic resistor card mounted adjacent the contact arm. The ceramic resistor card includes conductive traces arranged in parallel lines along its length so that as the fuel level sensor arm pivots it will impart its motion to the contact arm which moves linearly and causes the contact figure to move linearly across the conductive traces of the ceramic resistor card and change the resistance measurement which is transmitted to the fuel level gauge. In an embodiment, the cam member has a helical shape so that when the arm is pivoted in a circular motion it is transferred to the contact arm. In an embodiment, the cam member includes a semi-circular shaped slot. The contact arm includes a cylindrical pin that is inserted within the slot and upon rotation of the cam member the pin is moved through the slot in order to transfer a linear motion to the contact arm.
REFERENCES:
patent: 1611480 (1926-12-01), Meroni
patent: 4557144 (1985-12-01), Lucchini
patent: 5341679 (1994-08-01), Walkowski et al.
patent: 965459 (1948-04-01), None
Evans Steven M.
Larkin Daniel S.
Methode Electronics Inc.
Newman David L.
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