Leak detection in a closed vapor handling system using pressure, temperature and time

A method of leak detection in a closed vapor handling system of an automotive vehicle, wherein an engine is shut off, comprising:

• determining whether the engine is off;
• closing a shut off valve;
• providing a pressure sensing element, a temperature sensing element, and an engine management system to receive pressure and temperature signals from the pressure sensing element and temperature sensing element;
• obtaining a start temperature and start pressure;
• providing an evaluation temperature;
• calculating a temperature differential between the start temperature and the evaluation temperature;
• comparing the temperature differential to a temperature control value;
• incrementing a time counter if the temperature differential is greater than the temperature control value;
• setting the time counter to zero if the temperature differential is less than or equal to the temperature control value;
• computing a pressure differential between the start pressure and an evaluation pressure;
• comparing the pressure differential to a pressure control value;
• and
• comparing the time counter to a time control value if the pressure differential is not greater than the pressure control value.

An automotive evaporative leak detection system comprising:

• a pressure sensing element;
• a temperature sensing element;
• and
• a processor operatively coupled to the pressure sensing element and the temperature sensing element and receiving, respectively, pressure and temperature signals therefrom;
• wherein the processor calculates a temperature differential between a start temperature and an evaluation temperature, increments a time counter, computes a pressure differential between a start pressure and an evaluation pressure, and compares a time counter to the time control value.

An automotive evaporative leak detection system comprising:

• a differential tank pressure sensor located on a conduit between a fuel tank and a canister, the canister communicating with an engine and an atmosphere, the fuel tank communicating with the engine;
• a temperature sensor mounted on the fuel tank;
• a shut off valve located between the canister and the atmosphere;
• a control valve located between the canister and the engine;
• and
• a processor operatively coupled to the shut off valve, the control valve, the pressure sensor and the temperature sensor, the processor receiving pressure and temperature signals from the pressure and temperature sensors, respectively;
• wherein the processor opens and closes the shut off valve and control valve, calculates a temperature differential between a start temperature and an evaluation temperature, increments a time counter, computes a pressure differential between a start pressure and an evaluation pressure, and compares the time counter to a time control value.