Blower Housing Radial Draft for Static Tap Manufacturing
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Solution Overview
Problem
Molded clamshell water heater blowers face challenges in incorporating an exhaust pressure static tap due to the need for a uniform axial gap between the impeller backplate and scroll back wall, which is impractical to manufacture and results in inefficiencies and noise from excessive peripheral air velocities.
Innovation Solution
The blower design features a molded clamshell housing with radial draft in the scroll back wall, allowing a uniform axial gap and positioning the impeller close to both scroll walls while maintaining adequate scroll volume for airflow, using a unique impeller shape with back and front rings to optimize airflow and reduce reflow losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a uniform axial gap is maintained between the impeller backplate and scroll back wall, then the exhaust pressure static tap can operate efficiently, but the manufacturing complexity increases and cost rises
Solution Approach 1:
The patent applies local quality by providing a uniform axial gap only in the specific region where the exhaust pressure static tap is located, rather than maintaining uniform gap throughout the entire impeller assembly. This localized approach ensures efficient static tap operation while reducing overall manufacturing complexity and cost.
2Productivity
If the impeller is positioned close to both scroll walls, then scroll volume for airflow is optimized, but manufacturing precision requirements increase
Solution Approach 1:
The patent optimizes the impeller positioning to be close to both scroll walls specifically in the region where it benefits airflow efficiency and scroll volume utilization, while allowing greater tolerance in other regions. This selective positioning approach maximizes productivity without uniformly increasing manufacturing precision requirements across the entire assembly.
3Ease of manufacture
If radial draft is incorporated in the scroll back wall, then the design becomes practical to manufacture, but the structural complexity increases
Solution Approach 1:
The patent incorporates radial draft in the scroll back wall by changing the geometric parameters of the wall structure. This parameter modification allows the component to be manufactured using standard molding processes, making the design practical for production while the increased structural complexity is offset by the ease of manufacturing.
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 design achieves efficient operation of the exhaust pressure static tap with reduced noise and inefficiency, maintaining a uniform axial gap and adequate scroll volume for airflow, while being cost-effective and practical to manufacture.
Implementation Method 1
The impeller is rotatable about an impeller axis, the impeller axis defining perpendicular axial and radial directions
Implementation Method 2
The backplate back surface region generally circumscribes the impeller axis, the backplate back surface region converging radially inwardly as the backplate back surface region extends axially rearwardly from the first axial end toward the second axial end
Implementation Method 3
The scroll back wall has an exhaust pressure static tap opening adjacent the axial gap. The exhaust pressure static tap is connected to the exhaust pressure static tap opening
Data Source
AI summary
A blower has a blower housing of clamshell construction, including two housing members having a scroll back wall molded with radial draft, an impeller and a motor within the housing, and a static tap connected to the housing. The impeller has a backplate with a backplate back surface region of substantially the same radially converging shape as that of a front surface region of the scroll back wall formed by the radial draft, providing a substantially uniform axial gap between the backplate back surface region and the scroll back wall. The impeller has a ring connected by a skirt to the back plate to define a stepped area behind the ring. The impeller includes impeller blades extending forwardly from the impeller backplate and the ring and back fins extending rearwardly from the ring. The blower has a scroll width of about twice an impeller exhaust width.