Thermal Flowmeter Sub-Passage Sensor Segmentation
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Solution Overview
Problem
Conventional thermal flowmeters experience increased pressure loss and decreased flow velocity sensitivity due to sensor placement, which can lead to fluid turbulence and deteriorated noise performance and pulsation characteristics.
Innovation Solution
A thermal flowmeter design where a sub-passage is integrated into a circuit substrate with the flow rate measuring unit, and other sensors are placed in a separate space on the rear surface, reducing pressure loss and fluid obstruction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If various sensors are installed in the sub-bypass flow channel, then connection to circuit module is unified and assembly is simplified, but pressure loss inside the sub-bypass is increased
Solution Approach 1:
The patent divides the sensor installation space into two separate locations: the sub-bypass flow channel (for flow rate sensor) and the housing body (for inlet air temperature sensor and humidity sensor). This segmentation allows the flow rate sensor to be positioned where it won't obstruct fluid flow, eliminating pressure loss while maintaining simplified assembly through integrated housing design.
Solution Approach 2:
The patent transitions from arranging all sensors in a single linear flow path to distributing them across different spatial dimensions - sensors are placed in the housing body rather than all in the sub-bypass channel. This dimensional redistribution eliminates flow obstruction while preserving manufacturing simplicity.
2Device complexity
If various sensors are arranged side by side in the sub-bypass flow channel, then wiring connection is simplified, but flow velocity sensitivity of flow rate sensor is decreased
Solution Approach 1:
The patent segments the sensor group, placing the flow rate sensor in the sub-bypass flow channel where it can accurately measure flow velocity without obstruction, while other sensors are positioned in the housing body. This spatial segmentation preserves measurement precision while wiring is simplified through integrated circuit board design.
Solution Approach 2:
The patent introduces a circuit board as an intermediary that consolidates the wiring connections for all sensors. This allows sensors to be distributed in optimal positions for their respective functions while maintaining simplified wiring architecture through the centralizing role of the circuit board.
3Object-affected harmful factors
If various sensors are installed in the sub-bypass flow channel, then sensor protection from dust is improved, but noise performance or pulsation characteristic of flow rate sensor is deteriorated
Solution Approach 1:
The patent segments sensor placement so that the flow rate sensor remains in the sub-bypass flow channel where it benefits from protected positioning away from dust sources, while other sensors are placed in the housing body. The flow rate sensor's position in the bypass channel actually reduces exposure to dust and disturbances in the main flow path, improving noise performance.
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
This configuration improves flow velocity sensitivity and noise performance by minimizing pressure loss and fluid turbulence, while maintaining accurate measurement capabilities.
Implementation Method 1
a flow rate measuring unit that measures a flow rate of the measured gas in the sub-passage
Implementation Method 2
The flow rate sensor generates heat by a heater element
Data Source
AI summary
A thermal flowmeter includes a plurality of measuring units for stabilizing air flowing in a sub-passage, and improves noise performance or a pulsation characteristic of a flow rate sensor. The thermal flowmeter includes a flange fixed to an attachment part of a main passage, a sub-passage takes in a part of measured gas flowing in the main passage, a flow rate measuring unit measures a flow rate of the measured gas in the sub-passage, a circuit component controls the flow rate measuring unit, and the flow rate measuring unit and an electronic component are mounted on a circuit substrate. The sub-passage is formed in a substrate of the circuit substrate, the sub-passage on a surface side of the circuit substrate and a second space on a rear surface side are separated by the circuit substrate, and a pressure measuring unit and the circuit component are arranged in the second space.