Apparatus for measuring the fraction of liquid fuel in a fuel tank
First Claim
1. Apparatus for measuring the quantity of liquid fuel in a fuel tank for an internal combustion engine of a vehicle, said apparatus comprising a cylinder, a membrane in said cylinder dividing the cylinder into first and second chambers, means for connecting the first chamber to the fuel tank, means connecting the second chamber to the atmosphere, drive means acting on said membrane to produce displacement of the membrane in a direction to reduce the size of the first chamber, means for measuring displacement of said membrane from an initial defined position, to a displaced position produced by the drive means, sensor means for measuring gas pressure in a gas space in said fuel tank, means for closing communication of the fuel tank with ambient atmosphere during said measuring, the quantity of fuel in the fuel tank being determined from the pressure and displacement values measured, said drive means comprising an electric drive motor, a step-down transmission connected to said motor to be driven thereby, and a drive spindle mechanism drivingly connected to said transmission to produce displacement of the membrane in response thereto, a vent pipe connected to said fuel tank for venting the fuel tank to ambient atmosphere, said vent pipe including a first section connected to said first chamber and said fuel tank and a second section connected to ambient atmosphere and valve means for controlling communication between said first chamber and said second section of the vent pipe, said valve means comprising a valve member normally closing communication between said first chamber and said second section of said vent pipe, said valve member being openable in response to displacement of said membrane as produced by said spindle mechanism to provide communication between said first and second sections of said vent pipe.
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Accused Products
Abstract
The quantity of fuel in a fuel tank 1 is measured by determining the displacement of a membrane 19 and pressure values from a sensor 13. The displacement values of the membrane are representative of volume changes in a gas chamber in the tank 1 while the pressure values in the sensor 13 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 19, an electric motor 20 drives a step down transmission 25 which in turn drives a spindle mechanism 22 which is coupled to the membrane 19.
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Citations
24 Claims
- 1. Apparatus for measuring the quantity of liquid fuel in a fuel tank for an internal combustion engine of a vehicle, said apparatus comprising a cylinder, a membrane in said cylinder dividing the cylinder into first and second chambers, means for connecting the first chamber to the fuel tank, means connecting the second chamber to the atmosphere, drive means acting on said membrane to produce displacement of the membrane in a direction to reduce the size of the first chamber, means for measuring displacement of said membrane from an initial defined position, to a displaced position produced by the drive means, sensor means for measuring gas pressure in a gas space in said fuel tank, means for closing communication of the fuel tank with ambient atmosphere during said measuring, the quantity of fuel in the fuel tank being determined from the pressure and displacement values measured, said drive means comprising an electric drive motor, a step-down transmission connected to said motor to be driven thereby, and a drive spindle mechanism drivingly connected to said transmission to produce displacement of the membrane in response thereto, a vent pipe connected to said fuel tank for venting the fuel tank to ambient atmosphere, said vent pipe including a first section connected to said first chamber and said fuel tank and a second section connected to ambient atmosphere and valve means for controlling communication between said first chamber and said second section of the vent pipe, said valve means comprising a valve member normally closing communication between said first chamber and said second section of said vent pipe, said valve member being openable in response to displacement of said membrane as produced by said spindle mechanism to provide communication between said first and second sections of said vent pipe.
- 14. A method of controlling apparatus for measuring the quantity of liquid fuel in a fuel tank for an internal combustion engine of a vehicle having a cylinder, a membrane in said cylinder dividing the cylinder into first and second chambers, means for connecting the first chamber to the fuel tank, means connecting the second chamber to the atmosphere, drive means acting on said membrane to produce displacement of the membrane in a direction to reduce the size of the first chamber, means for measuring displacement of said membrane from an initial defined position, to a displaced position produced by the drive means, sensor means for measuring gas pressure in a gas space in said fuel tank, means for closing communication of the fuel tank with ambient atmosphere during said measuring, the quantity of fuel in the fuel tank being determined from the pressure and displacement values measured, said drive means comprising an electric drive motor, a step-down transmission connected to said motor to be driven thereby, and a drive spindle mechanism drivingly connected to said transmission to produce displacement of the membrane in response thereto, and control means connected to said drive means, said means for measuring displacement of said membrane and said pressure sensor means to evaluate the fraction of liquid fuel in the fuel tank, said method comprising the steps of:
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15. establishing a measurement readiness state by supplying the pressure in the tank to said pressure sensor means;
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2. determining internal tank pressure with respect to ambient atmosphere from said pressure sensor means; 3. closing the pressure sensor means to ambient atmosphere; 4. activating the drive motor; 5. allowing displacement of the membrane to proceed to approximately 5% of its maximum possible displacement; 6. establishing measurement time at zero, the pressure at the pressure sensor means as an initial pressure value, and the displacement of the membrane as an initial displacement value when the membrane has been displaced to approximately 5% of its maximum possible displacement; 7. measuring changes in pressure and displacement values as the membrane is displaced; 8. determining that the changes in pressure and displacement values exceed the initial values; 9. deactivating the electric motor; 10. determining measurement time, membrane displacement values, and pressure sensor values; 11. calculating fuel content in the tank based on said values and the general equation of state of an ideal gas; 12. producing an output signal indicative of fuel content; 13. reconnecting the pressure sensor means to ambient atmosphere and driving the electric motor in reverse to return the membrane to is measurement readiness position; and 14. re-establishing a measurement readiness state as in step 1.
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Specification