Methods and systems for mobile carbon dioxide monitoring
View Patent ↗A telematics device coupled to vehicle onboard computer system calculates carbon dioxide output of the vehicle. The device uses inputs from existing vehicle performance and parameter sensors, such as speed, fuel efficiency, mass air flow and oxygen present in the vehicle's exhaust, to calculate carbon dioxide output. Speed divided by fuel efficiency results in gallons per hour. An emmission factor, EF, multiplied by the gallons per hour results in weight of carbon dioxide produced by the vehicle per hour. Dividing EF by the efficiency results in pounds per mile. Using input from the mass air flow and oxygen sensors, with an approximation of gasoline molecular weight may produce more accurate results without using EF. If the sensors do not provide values in the units needed, a calibration curve for the mass air flow sensor and oxygen sensor may be used. The telematics device can display the results or upload them.
1. A method for determining the weight of carbon dioxide produced by burning a mixture of air and fuel in an internal combustion engine using a value sampled from a mass air flow sensor signal and using a value sampled from an oxygen sensor signal, comprising:
A. dividing the value sampled from the mass air flow sensor signal by the value sampled from the oxygen sensor signal;
B. multiplying the quotient that results from performing step A by a chemical conversion factor; and
C. processing the product that results from performing step B by a computer processor.
2. The method of claim 1 wherein the value sampled from the oxygen sensor signal is converted to an O 2 value that is used to lookup a corresponding air to fuel ratio in a table, and the value sampled from the mass air flow sensor signal is divided by the air fuel ratio from the table corresponding to the value sampled from the O 2 sensor when performing step A.
3. The method of claim 1 wherein the calculation of the chemical conversion factor assumes a particular fuel and a corresponding molecular composition thereof.
4. The method of claim 3 wherein the calculation of the chemical conversion factor assumes the particular fuel is Octane.
5. The method of claim 1 wherein the chemical conversion factor is the molecular weight of carbon dioxide divided by the atomic weight of carbon times the atomic weight of the carbon atoms in a molecule of the fuel divided by the molecular weight of the fuel.
6. The method of claim 1 wherein the step of processing includes storing the product that results from performing step B to a memory.
7. The method of claim 6 wherein the step of processing includes displaying the product stored in memory with a display device.
8. The method of claim 3 wherein the calculation of the chemical conversion factor assumes that the engine burns Octane and that the chemical conversion factor is (44/12)×(96/114), or 3.0877.