Fuel tank module control system

Abstract

A fuel tank module control system configured to measure fuel level and fuel tank vapor pressure, the system having an aspirator to use air or liquid fuel to vapor, an oscillator cyclically producing pressurized vapor, and a pressure sensor that alternately measures the pressurized vapor provided by the oscillator and the pressure of a fuel column. A check valve is provided downstream of the sensor to restrict the flow of vapor in a single direction. To determine the fuel level, the differential of the square wave output of the sensor is calculated. To determine if there are any leaks in the fuel tank, the tank vapor pressure is measured when the engine is off.

Description

FIELD OF THE INVENTION [0001] The present invention relates generally to sensors, and more particularly to a fuel tank module that utilizes a single sensor to measure fuel tank vapor pressure and fuel level. BACKGROUND OF THE INVENTION [0002] A fuel tank of a gasoline-powered passenger car typically includes a fuel level sensor and a fuel tank-pressure sensor. The fuel level sensor measures the amount of fuel remaining in the fuel tank so that the driver is alerted when the fuel level is low. By monitoring the fuel level measurements, the driver can refuel, as necessary, and can avoid the inconvenience of running out of fuel while driving. [0003] The fuel tank pressure sensor measures the fuel tank pressure with respect to the atmosphere and detects leaks in the fuel venting system. In the United States, leak detection devices are currently required under the Environmental Protection Agency's “OBD II” requirements. Although leak detection algorithms can vary, a typical leak detector...

AI Technical Summary

Benefits of technology

The system provides accurate and reliable fuel level and leak detection with minimal risk of damage, eliminating offset and slope errors, and enabling a single sensor to perform both functions, reducing costs and improving reliability.

Problems solved by technology

A disadvantage of such a sensor is that if the tube is immersed in liquid for an extended period of time, the air in the tube eventually dissolves in the surrounding liquid.

The liquid enters the tube and any resulting pressure measurement is compromised.

Given the limitation of such a sensor, it is only a viable option for appliances such as washing machines, were the sensor is immersed in the water for a relatively short period of time during each cycle, and thereafter the water drains from the washing machine tub.

Because the sensor would be immersed in gasoline continuously, the pressure reading could be compromised when air in the tube dissolved in the gasoline and the gasoline entered the tube.

Frequently, the sensor is bent and damaged during installation.

Furthermore, even if the sensor is threaded through the hole without damage, if the float hits the bottom of the tank, it may stick there, rendering it useless.

Images