Thermal Flowmeter Heat Resistor Power Optimization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Thermal flowmeters face high power consumption issues when using power supply from an ECU, especially due to high airflow velocities in internal combustion engines, leading to increased power requirements for maintaining heat resistor temperature, which cannot be reduced without compromising sensitivity and resistance to contamination.
Innovation Solution
A thermal flowmeter design where the heat resistor is powered to maintain a temperature higher than the fluid temperature by a specific temperature increase ΔTh, with the length Wh of the heat resistor between 100 micrometers and 400 micrometers, satisfying the relationship 1.4≦ΔTh·Lh/Ph≦2.8, allowing for low power consumption without reducing the heating temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If power supply from ECU is used, then device complexity is reduced, but power consumption is limited
Solution Approach 1:
The patent changes the operating parameters of the thermal flowmeter by optimizing the heat resistor length to 100-400 micrometers and controlling the temperature increase to 20-100°C, enabling operation within the limited power constraints of ECU supply while maintaining measurement functionality
2Use of energy by moving object
If heating temperature is reduced, then power consumption is reduced, but sensitivity is decreased
Solution Approach 1:
The patent optimizes the heat resistor length parameter to a specific range (100-400 micrometers) that enables effective heat transfer and temperature detection at lower power consumption levels, maintaining sensitivity without requiring high heating temperatures
Solution Approach 2:
The patent dynamically adjusts the operating temperature increase to an optimal range (20-100°C) rather than using fixed high temperatures, allowing the system to maintain measurement precision while consuming less power
3Measurement precision
If heat resistor length is increased, then sensitivity is improved, but power consumption is increased
Solution Approach 1:
The patent identifies and implements an optimal parameter range for heat resistor length (100-400 micrometers) that balances sensitivity improvement with power consumption constraints, preventing excessive power usage while maintaining adequate measurement precision
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables low power consumption and maintains sensitivity and resistance to contamination, reducing power consumption while maintaining the heating temperature of the heat resistor, thus optimizing operational efficiency.
Implementation Method 1
a heat resistor 6 supplied with power so that a temperature of the heat resistor 6 is higher than a fluid temperature by a temperature increase ΔTh
Data Source
AI summary
To reduce power consumption by a thermal flowmeter while good flow-rate detection sensitivity is maintained, it is only necessary to reduce power consumption by a heat resistor under predetermined conditions. Specifically, provided that a width Wh of the heat resistor is between 100 micrometers and 400 micrometers inclusive (100≦Wh≦400), it is only necessary that a relationship among the length Lh of the heat resistor, a temperature increase ΔTh for the heat resistor, and a maximum permissible power Phmax to be supplied to the heat resistor be set so as to satisfy a formula 1.4≦ΔTh·Lh/Ph max≦2.8 in order to maintain good flow-rate detection sensitivity. Accordingly, the length of the heat resistor and the temperature increase in the heat resistor are set so that the maximum power consumption can be reduced within a range in which the formula is satisfied.