Fuel Consumption Calculation Unit Using Dynamic Exhaust Gas Density
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Solution Overview
Problem
Existing fuel consumption measurement methods, such as the carbon balance method, suffer from response delays and measurement errors due to the use of constant exhaust gas density, particularly when the air-fuel ratio is in the rich region, and are unsuitable for instantaneous measurements in vehicles with frequent fuel cuts and electrical driving.
Innovation Solution
A fuel consumption calculation unit and program that directly measure exhaust gas flow rate and air-fuel ratio, adjusting exhaust gas density based on the air-fuel ratio to reduce measurement errors, eliminating the need for a sampling flow path and dilution devices, thereby allowing for high-response, accurate fuel consumption measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a constant value for exhaust gas density is used in fuel consumption calculation, then the calculation is simplified, but measurement error increases when air-fuel ratio is in the rich region
Solution Approach 1:
The exhaust gas density is changed dynamically based on the air-fuel ratio. When the air-fuel ratio is in the lean region, a constant density value is used, but when it enters the rich region, the density is adjusted according to the actual air-fuel ratio to maintain measurement accuracy
Solution Approach 2:
The exhaust gas density parameter is changed from a constant value to a variable value that depends on the air-fuel ratio. The calculation unit adjusts the density parameter based on whether the air-fuel ratio is in the lean or rich region, thereby improving measurement accuracy without significantly complicating the calculation process
2Measurement precision
If diluted exhaust gas is introduced through a sampling flow path to an exhaust gas analyzer, then component concentrations can be measured, but response delay occurs due to gas congestion
Solution Approach 1:
The invention extracts only the necessary measurement functions (flow rate and air-fuel ratio) directly from the exhaust gas flow path, eliminating the need for dilution and complex sampling systems. This allows direct measurement without response delay while maintaining sufficient measurement capability for fuel consumption calculation
Solution Approach 2:
The measurement function is segmented into two separate sensors: a flow rate sensor for measuring exhaust gas flow rate and an air-fuel ratio sensor for measuring air-fuel ratio. This segmentation allows each sensor to perform its specific function directly in the exhaust gas flow path without the need for dilution and complex sampling, achieving both measurement accuracy and fast response
3Measurement precision
If a fuel flowmeter is used to directly measure fuel consumption, then instantaneous fuel consumption can be measured, but it is difficult to install in a completed vehicle without disturbing the fuel system
Solution Approach 1:
The invention uses exhaust gas parameters (flow rate and air-fuel ratio) as intermediaries to calculate fuel consumption indirectly. Instead of directly measuring fuel flow, the system measures exhaust gas properties and uses these as mediators to derive the fuel consumption value, avoiding the need to install sensors in the fuel system
Solution Approach 2:
The mechanical fuel flow measurement system is replaced with a sensor-based measurement system that uses exhaust gas analysis. Instead of using a mechanical fuel flowmeter that requires physical installation in the fuel line, the invention substitutes this with non-intrusive sensors (flow rate sensor and air-fuel ratio sensor) installed in the exhaust gas flow path, eliminating the need for fuel system modifications
Data Source
AI summary
The present invention is intended to, at the time of directly measuring a flow rate of exhaust gas flowing through an exhaust gas flow path and an air-fuel ratio of the exhaust gas, and on the basis of the flow rate and air-fuel ratio of the exhaust gas, calculating fuel consumption, reduce a measurement error of the fuel consumption. Also, the invention is a fuel consumption calculation unit that, with use of an exhaust gas flow rate obtained by a flow rate sensor provided in an exhaust gas flow path through which exhaust gas of an engine flows, and an air-fuel ratio obtained by an air-fuel ratio sensor provided in the exhaust gas flow path, calculates fuel consumption of the engine, and on the basis of the air-fuel ratio obtained by the air-fuel ratio sensor, changes a value of exhaust gas density used for the calculation of the fuel consumption.