Power Tool Injection Valve Cooling via Fan Housing Opening
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Solution Overview
Problem
In power tools with internal combustion engines, especially two-stroke engines in hand-guided tools, vapor bubble formation in the fuel system due to high temperatures and low fuel pressure impairs fuel supply, leading to engine operation issues.
Innovation Solution
A connecting opening in the fan wheel housing allows cooling air to flow directly into a targeted cooling area where the injection valve is positioned, preventing vapor bubble formation and ensuring effective cooling of the injection valve, which is indirectly cooled through a holder attached to the crankcase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the injection valve is cooled by arranging it above the fan wheel on the suction side, then the fuel valve and engine block are cooled by sucked-in air, but the cooling action is not targeted enough and vapor bubbles still form in the injection valve
Solution Approach 1:
The patent creates a dedicated cooling area with a connecting opening in the fan wheel housing that allows cooling air to flow directly into the region surrounding the injection valve. This localized cooling approach ensures that the injection valve receives sufficient cooling air to prevent vapor bubble formation, while other components like the engine block receive cooling through different pathways. The holder made of thermally insulating material further localizes the cooling effect to the injection valve area.
Solution Approach 2:
The patent introduces a holder made of thermally insulating material (such as plastic) as an intermediary between the injection valve and the crankcase. This holder serves as a thermal barrier that prevents heat from the crankcase from transferring to the injection valve, while still allowing the injection valve to be cooled by the cooling air flowing through the connecting opening. The air guiding component also acts as an intermediary to direct cooling air flow to the injection valve area.
2Ease of operation
If the engine is designed to be compact for simple handling, then space is limited, but high temperatures and low fuel pressure cause vapor bubble formation
Solution Approach 1:
The patent combines the cooling functions for different components into a unified fan wheel housing structure. The housing integrates the fan wheel, the connecting opening for injection valve cooling, and air guiding passages into a single compact assembly. This merging allows efficient space utilization while providing targeted cooling to the injection valve without increasing the overall size of the engine, thus maintaining compactness for simple handling.
3Reliability
If cooling air is conveyed continuously to the injection valve, then vapor bubble formation is prevented, but energy consumption increases
Solution Approach 1:
The patent designs the cooling system to be self-regulating, where the injection valve cooling is achieved using the same cooling air flow that is already being generated by the fan wheel for engine cooling. The connecting opening allows the injection valve to utilize this existing cooling air flow without requiring an additional cooling source or increasing fan wheel power consumption. The system essentially uses itself to cool the injection valve, preventing vapor bubble formation without additional energy input.
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 maintains the injection valve at a lower temperature, preventing vapor bubble formation and ensuring reliable fuel supply to the engine, even when the engine is turned off, by using a thermally insulating air guiding component and radial sealing to minimize heat transfer.
Implementation Method 1
a connecting opening is provided in the fan wheel housing by means of which cooling air that is conveyed by the fan wheel flows into the cooling area
Implementation Method 2
by using a thermally insulating air guiding component and radial sealing to minimize heat transfer
Data Source
AI summary
A power tool has an internal combustion engine with an injection valve through which fuel is supplied to the internal combustion engine; a crankcase; and a crankshaft arranged in the crankcase so as to be rotatable about an axis of rotation. A fan wheel housing is provided and a fan wheel is arranged in the fan wheel housing and conveys cooling air to the internal combustion engine. In the fan wheel housing a connecting opening is formed. The injection valve is arranged in a cooling area, wherein cooling air is supplied by the fan wheel through the connecting opening to the cooling area.