Data processing: measuring – calibrating – or testing – Measurement system in a specific environment – Mechanical measurement system
Reexamination Certificate
2002-01-09
2003-07-22
Lefkowitz, Edward (Department: 2856)
Data processing: measuring, calibrating, or testing
Measurement system in a specific environment
Mechanical measurement system
C702S100000, C073S001730, C073S149000, C073S29000R
Reexamination Certificate
active
06597998
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is generally related to a method for determining the amount of liquid in a reservoir as a function of a linear measurement provided by a depth determining device and, more particularly, to a method for automatically calibrating the relationship between the liquid depth and the volume of the liquid remaining in the reservoir notwithstanding the potentially non uniform shape of the liquid reservoir.
2. Description of the Prior Art
Many different types of fuel tanks and fuel depth sensors are known to those skilled in the art. Most fuel tanks are provided with a sensor that determines, either directly or indirectly, the amount of liquid fuel remaining in the fuel tank. Most typically, a float mechanism is used to measure the depth of the liquid in the reservoir and that measured depth is used to determine or represent the amount of liquid remaining in the reservoir. These types of devices are most commonly used in fuel tanks, such as the fuel tanks of automobiles, boats, and other vehicles.
When a fuel tank, or other liquid reservoir, has an irregular shape, the relationship between the depth of the fluid within the reservoir and the volume of fluid remaining in the reservoir is not always linear. In other words, each decrease in the depth, by a particular incremental magnitude, does not always represent the same change in the liquid volume remaining in the reservoir. Most fuel tanks are not purely parallelepipeds, with six parallel faces. If the tank is a parallelepiped, the volume remaining in the tank generally has a linear relationship with the depth of the liquid actually remaining in the tank. However, this is rarely the case in actual practice since most fuel tanks have irregular shapes, particularly when used in marine vessels.
Many different approaches have been used to address the accuracy of fuel measurement in these types of situations.
U.S. Pat. No. 5,485,740, which issued to Lippmann et al on Jan. 23, 1996, describes a method of calibration for gauging fuel in an automotive tank. The maximum fuel level is determined in a fuel tank of undetermined size using a fuel level sender which is referenced to the tank bottom. A minimum full value is selected for a given type of tank and when the sender signal goes below a percentage of that value and subsequently goes above the minimum full value, a fueling event is recognized and the current fuel sender value is adopted as the maximum full value. Where a heavily filtered signal is used to minimize the effect of fuel slosh, the maximum full value is subject to increasing to higher values occurring during a short period after fueling to allow recovery of the filtered signal. An empty value is calibrated before the vehicle is initially fueled. A maximum empty level is initially set and if a lower level is measured when the ignition is turned on, the lower level is set as the empty value. This calibration is terminated when the tank is fueled above the minimum full value.
U.S. Pat. No. 5,752,409, which issued to Lippmann et al on May 19, 1998, describes a method of accurately gauging fuel in an automotive tank. This patent is generally related to U.S. Pat. No. 5,485,740.
U.S. Pat. No. 6,289,728, which issued to Wilkins on Sep. 18, 2001, describes an apparatus and method for determining the amount of liquid contained in a storage tank. A tube has a closed bottom end and is disposed within the tank in a substantial vertical orientation with the closed end of the tube immersed in the liquid and the open end of the tube protruding from the top of the tank. An elongate member has a longitudinal edge defining a varying profile corresponding to the predetermined relationship between the liquid level and the barometric content. This member is slidably received within the tube. A float is slidable vertically along the exterior of the tube and is magnetically coupled to the elongate member such that as the float rises or falls in response to a change in liquid level, the elongate member will be vertically displaced within the tube. A measuring device position proximate the open end of the tube measures the distance between the longitudinal edge of the elongate member and a reference plane aligned substantially parallel to the longitudinal axis of the elongate member, the distance being directly proportional to the volumetric content of liquid contained in the tank.
U.S. Pat. No. 4,731,730, which issued to Hedrick et al on Mar. 15, 1988, describes a universal fuel quantity indicator apparatus. The apparatus includes a digital fuel quantity indicator having an internal microprocessor control unit and a removably connectable digital calibration trim interface which enables the fuel quantity indicator to be reconfigured for different fuel tanks by varying selectable fuel tank parameters, such as constants associated with a fuel quantity determination based on calculations of capacitance of a tank capacitor array and a compensator capacitor. The interface includes up/down steering control buttons which control selection and storage and of the selected parameters, a mode selection jumper which selects between a RUN mode a CALIBRATE mode for the indicator, and an alternate static memory which stores the configured parameters for loading to the indicator internal static memory associated with the microprocessor in the CALIBRATE mode to configure the indicator for a specific fuel tank.
U.S. Pat. No. 4,724,705, which issued to Harris on Feb. 16, 1988, describes a fuel gauge. The apparatus is provided for determining the quantity of fuel in a fuel tank having a contoured interior wall. The apparatus includes a buoyant member for floating on the top surface of fuel in the fuel tank, a conductor supported on the buoyant member to float therewith, and a pattern of resistance in electrical contact with the floating conductor. The pattern of resistance is selected to correspond to the contour of the interior wall. Thus, the resistance pattern is coded to represent the volume profile of the fuel tank. A voltage is applied across the conductor and the pattern of resistance. The floating conductor and the pattern of resistance cooperate to provide a value of resistance corresponding to the depth of fuel in the fuel tank at the measurement location. An indicator interprets that value of resistance to determine the instantaneous quantity of fuel in the fuel tank.
U.S. Pat. No. 4,358,947, which issued to Greene et al on Nov. 16, 1982, describes a method and apparatus for volumetric calibration of liquid flow sensor output signals. A liquid flow sensor produces output signals which are monitored over a known volume of flowing liquid. That monitored signal value is scaled according to a predetermined volume of liquid to provide a correction factor, whereby the output signal of the flow sensor is continually corrected to provide an expected number of flow sensor pulses per unit volume.
U.S. Pat. No. 5,315,867, which issued to Hartel et al on May 31, 1994, describes an apparatus for measuring the fraction of liquid fuel in a fuel tank. The quantity of fuel in a fuel tank is measured by determining the displacement of a membrane and pressure values from a sensor. The displacement values of the membrane are representative of volume changes in a gas chamber in the tank while the pressure values in the sensor are representative of the pressure of the gas chamber. With these values, the fuel content in the gas tank can be determined from the general equation of state of an ideal gas. In order to displace the membrane, an electric motor drives a step down transmission which in turn drives a spindle mechanism which is coupled to the membrane.
U.S. Pat. No. 4,840,064, which issued to Fudim on Jun. 20, 1989, describes a liquid volume monitoring apparatus and method. The apparatus is disclosed for determining the volume of liquid in a container which is being provided with an in flow and an out flow of liquid such that there normally remains an ullage volume in the container filled with gas. A time
Brunswick Corporation
Cygan Michael
Lanyi William D.
Lefkowitz Edward
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