Pump Bellows Wall Thickness for Low-Temperature Resetting
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Solution Overview
Problem
Handheld work apparatuses with pump bellows face challenges in achieving sufficient resetting forces, especially at low temperatures, due to the limitations of existing designs which often require additional components like helical compression springs.
Innovation Solution
The pump bellows is designed with a thickened main section between the fastening and dome-shaped sections, where the wall thickness is at least 10% greater than the dome-shaped section, allowing for increased resetting forces while maintaining a simple configuration and minimal actuation force requirement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the wall thickness of the pump bellows is increased to achieve sufficient resetting forces, then the resetting force is improved, but the actuating force required to push in the pump bellows increases
Solution Approach 1:
The pump bellows is designed with non-uniform wall thickness, where the main section has increased wall thickness to provide high resetting forces, while the dome-shaped section maintains smaller wall thickness to require minimal actuating force. This local differentiation of structural properties resolves the contradiction between needing strong resetting force and easy actuation.
2Force
If a helical compression spring is inserted into the pump bellows to assist resetting, then the resetting force is improved, but the device complexity increases
Solution Approach 1:
The helical compression spring commonly used in pump bellows is completely removed from the design. Instead, the resetting function is achieved through the elastic properties of the pump bellows material itself, specifically by utilizing the thickened main section that provides sufficient resetting force through its increased wall thickness, thereby simplifying the overall device structure.
Solution Approach 2:
The pump bellows structure itself provides the resetting force through its elastic deformation characteristics. The thickened main section is designed to store elastic energy during actuation and release it during resetting, making the system self-sufficient without requiring external springs or additional resetting mechanisms.
3Productivity
If the wall thickness in the main section is increased to achieve rapid resetting, then the resetting speed is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The pump bellows is divided into distinct sections with different wall thickness characteristics: the main section with increased and relatively uniform wall thickness for rapid resetting, and the dome-shaped section with smaller wall thickness for easy actuation. This segmentation allows each section to be optimized for its specific function while managing manufacturing precision requirements.
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 enables rapid resetting of the pump bellows into its unactuated state with high resetting forces, even at low temperatures, while keeping the actuation force for the dome-shaped section substantially the same, and increasing the force required for the main section.
Implementation Method 1
a thickening of the pump bellows in a main section of the pump bellows... The wall thickness of the pump bellows in the main section is greater than the wall thickness of the dome-shaped section... achieving large resetting forces, and, as a result, rapid resetting of the pump bellows into the unactuated state
Data Source
AI summary
A handheld work apparatus has a fuel supply system and a pump for delivering fuel from the fuel supply system. The pump has an elastic pump bellows which can be actuated by the operator. The pump bellows has a fastening section at which the pump bellows is fastened to a housing. The pump bellows has a main section and a roof section, wherein the roof section has a dome-shaped section adjoining the main section and a cap which adjoins the dome-shaped section and closes off the dome-shaped section. In order to achieve a rapid return of the pump bellows from the actuated position into the unactuated position, even at low temperatures, it is provided that the smallest wall thickness (g) of the main section is at least 10% greater than the smallest wall thickness (h) of the dome-shaped section.