Air Flow Measuring Device Recess Design for Injection Molding
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Solution Overview
Problem
Conventional air flow measuring devices face deformation issues during secondary formation due to pressure from injected resin, which can alter the shape of the bypass flow passage, compromising the desired output characteristics of the flow sensor.
Innovation Solution
The air flow measuring device incorporates a first housing with a recessed outer surface and a second housing formed through secondary formation, where the first housing is held on the lower side, allowing for increased die cramp area contact during resin injection, thereby reducing deformation and maintaining the bypass flow passage shape.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If secondary formation is performed with the first housing as a primary formed part, then the second housing can be formed integrally with the first housing, but the first housing may be deformed or damaged due to the pressure of injected resin
Solution Approach 1:
A recess is formed on the upper side of the hollow part in the first housing before the secondary formation process. This recess serves as a preliminary structural feature that increases the die cramp area during injection molding, providing enhanced support to the hollow part before the resin injection pressure is applied, thereby preventing deformation of the bypass flow passage
Solution Approach 2:
The recess is strategically positioned only on the upper side of the hollow part where the resin injection pressure is most likely to cause deformation. This localized structural modification provides targeted reinforcement exactly where needed, rather than uniformly thickening the entire first housing, thus maintaining manufacturing precision in the critical bypass flow passage area while enabling integral formation
2Ease of manufacture
If the first housing is deformed, then the shape of the bypass flow passage changes, but the desired output characteristics of the flow sensor cannot be obtained
Solution Approach 1:
The recess is formed in advance on the first housing to provide structural reinforcement before the secondary formation process occurs. This preliminary structural preparation ensures that the bypass flow passage maintains its designed shape during resin injection, thereby preserving the flow characteristics needed for accurate flow sensor measurements
Solution Approach 2:
The recess structure creates a counteracting effect against the resin injection pressure by increasing the die cramp area. This preliminary anti-action prevents the pressure from deforming the hollow part and bypass flow passage, ensuring that the flow passage shape remains consistent with the design requirements for accurate flow sensing
Data Source
AI summary
An air flow measuring device is adapted to be attached to a duct. The device includes a first housing, a second housing, and a flow sensor. The first housing defines a bypass flow passage which takes in a part of air flowing in the duct, and includes a hollow part and a recess. The bypass flow passage is formed in the hollow part. The recess is formed on an upper side of the hollow part in a vertical direction of the device, and at the recess, an outer surface of the first housing is recessed inward of the first housing. The second housing is formed through secondary formation with the first housing as a primary formed part. The first housing is held on a lower side of the second housing in the vertical direction. The flow sensor is disposed in the bypass flow passage.