Electronic Recoil Starter Control for Handheld Power Tools
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Solution Overview
Problem
Hand-held tools with internal combustion engines face challenges in simplifying the starting process and reducing operator errors, as existing mechanical starting devices require manual adjustment and reactivation after each use.
Innovation Solution
A hand-held tool with an electronic control device that automatically switches between starting and operating modes, controlling the spark plug and fuel valve to manage ignition and fuel supply, eliminating the need for mechanical components and allowing for automatic mode switching after engine shutdown, enabling seamless restarts without manual intervention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mechanical starting device with manual adjustment is used, then the starting process can be controlled, but the device complexity increases and operator errors occur due to manual reactivation requirements
Solution Approach 1:
The patent replaces the mechanical starting device with an electronic control system. The control device electronically actuates the choke element and throttle valve instead of using mechanical linkages, eliminating the need for manual adjustment mechanisms and reducing device complexity while improving reliability through automated electronic control.
Solution Approach 2:
The control device automatically manages the starting process without requiring manual intervention. After the engine starts, the control device autonomously adjusts the choke and throttle settings, and after engine shutdown, it automatically returns to the starting position, eliminating the need for operator reactivation and reducing potential for human error.
2Ease of operation
If mechanical components for starting mode are used, then the starting function can be achieved, but the ease of operation decreases due to manual adjustment requirements
Solution Approach 1:
The control device performs automatic self-service by returning to the starting position after engine shutdown without requiring manual intervention. This eliminates the time loss associated with manual reactivation and simplifies operation to merely pressing the start button, significantly improving ease of operation.
Solution Approach 2:
The control device prepares the engine for starting by automatically setting the choke and throttle to the correct starting positions before the start button is pressed. This preliminary automatic preparation eliminates the need for manual adjustment and reduces the time required for the starting process.
3Device complexity
If electronic control is used for mode switching, then the device complexity reduces and automation increases, but the manufacturing precision requirements increase
Solution Approach 1:
The patent substitutes mechanical control components with an electronic control system that manages the choke and throttle valves. This reduces overall device complexity by eliminating mechanical linkages and adjustment mechanisms, while the electronic system's ability to precisely control valve positions actually improves manufacturing tolerance requirements compared to mechanical systems.
Data Source
Figure 1
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AI summary
A hand-held power tool (1) comprises a tool, an internal combustion engine (10) for powering the tool, a manually operated recoil starter (13) for the internal combustion engine (10), and a stop button (11) operated by the user to switch off the internal combustion engine (10). A throttle element (30) is arranged in an intake port (25) of the internal combustion engine (10). The power tool (1) has a control unit (36) for controlling a spark plug (33) and a fuel valve (34) of the internal combustion engine (10). The control unit (36) has a starting mode in which the internal combustion engine (10) can be started via the recoil starter (13), and an operating mode in which the user can control the internal combustion engine (10) by adjusting the throttle element (30) to change the speed (n) of the internal combustion engine (10).The operating mode and the starting mode differ in the control of the ignition timing (ZZP) and the amount of fuel supplied via the control unit (36). When the internal combustion engine (10) is started from the switched-off state, the control unit (36) is automatically in starting mode, so that the implement (1) is immediately ready to be started again via the recoil starter (13) after the internal combustion engine (10) is switched off.