Importance

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Abstract

A method and apparatus for dispensing natural gas into the natural gas vehicle cylinder of a motor vehicle is disclosed. The natural gas dispensing system includes a pressure transducer and a temperature transducer for measuring the pressure and temperature, respectively, of the supply gas as it is passed toward a dispenser, a second pressure transducer for measuring the pressure within the natural gas vehicle cylinder, an ambient air temperature transducer for measuring ambient air temperatures at the dispensing site, and a mass flow meter for measuring the gas mass injected into the vehicle cylinder. Each transducer and the mass flow meter emits a data signal to a control processor which automatically dispenses compressed gas to the vehicle cylinder, as well as maximizing the amount of gas mass injected into the cylinder. The control processor maximizes the mass of compressed gas injected into the vehicle cylinder by injecting a first mass of compressed gas into the cylinder and calculating a first volume estimate in response thereto, estimating a second mass of compressed gas required to fill the cylinder to a first predetermined fill state, and then estimating a third mass of compressed gas required to fill a reference gas cylinder to the first predetermined fill state in response thereto. Thereafter, the second mass of compressed gas is injected into the cylinder, the gas mass being injected into the cylinder from the initial state being measured, as well as the pressure of the compressed gas within the container resulting from the injection of the second gas mass being measured, whereupon the control processor estimates a second volume of the gas container in response thereto. Thereafter, the control process may be used to either perform a final fill step to complete the gas mass injection into the cylinder, or may perform a second intermediate fill step prior to the final fill step for greater accuracy in determining tank volume during the fill process.

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First Claim