Starter Apparatus Damping Spring Gap Compensation
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Solution Overview
Problem
Existing starter apparatus for internal combustion engines in portable handheld tools face issues with operational reliability and durability due to gaps between components, leading to damping spring fracture, caused by tilting and manufacturing tolerances.
Innovation Solution
The starter apparatus incorporates recesses on the supports' outer periphery to ensure uniform damping spring contact, a disc between supports to compensate for tolerances and prevent gap formation, and a helical damping spring with inwardly bent ends for secure assembly and high resistance torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the supports are designed with smooth outer periphery, then the damping spring can be easily manufactured, but contamination on the support surface causes non-uniform contact leading to spring fracture
Solution Approach 1:
The support surface is designed with recesses that create a porous-like structure, allowing contamination to be collected in these recesses rather than on the contact surface. This maintains uniform contact between the damping spring and support while being easy to manufacture using standard machining processes.
Solution Approach 2:
The recesses act as an intermediary element between the support surface and the damping spring, capturing contaminants and preventing them from interfering with the contact interface. This mediator structure ensures reliable spring contact without complicating the manufacturing process.
2Reliability
If manufacturing tolerances are reduced to eliminate gaps between entrainer and rope reel, then the damping spring cannot force into gaps improving reliability, but manufacturing cost and complexity increase
Solution Approach 1:
Instead of trying to eliminate gaps through tighter tolerances, the invention accepts the presence of gaps and designs the support with recesses that specifically address the problem. The recesses capture contaminants and prevent spring damage even when gaps exist, converting the harmful effect of gaps into a manageable condition.
Solution Approach 2:
The invention changes the geometric parameters of the support surface by adding recesses, rather than changing the dimensional tolerances of the components. This parameter change allows the system to tolerate gaps while maintaining reliability.
3Force
If the damping spring is designed with high tension force to ensure reliable engagement, then the spring provides sufficient force for starting, but the spring is more susceptible to fracture from non-uniform contact
Solution Approach 1:
The recessed structure of the support creates a porous-like surface that protects the high-tension damping spring from point loads and non-uniform contact. Contaminants are captured in the recesses, allowing the spring to maintain high tension forces without being susceptible to fracture from surface irregularities.
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 enhances operational reliability and durability by maintaining consistent contact and preventing damping spring fracture, ensuring reliable engine starting in portable handheld tools.
Implementation Method 1
a damping spring connecting the actuating unit and the entrainer to each other; the damping spring having a first end connected to the actuating unit and a second end connected to the entrainer
Data Source
AI summary
A starter device for an internal combustion engine (10) has an actuating device and an entrainer (24) can be coupled to the crankshaft (13) of the engine (10). The entrainer (24) and the actuating device are rotatably journalled about a rotational axis (14). The entrainer (24) and the actuating device are connected to each other via a damping spring (23). The damping spring (23) is connected with a first end (26) to the actuating device and with a second end (27) to the entrainer (24). The entrainer (24) and the actuating device have respective supports (21, 42). The damping spring (23) is mounted on the outer periphery of the two supports (21, 42). In the direction of the rotational axis (14), a disc (22) is mounted between the two supports (21, 42) in order to avoid the situation that the damping spring (23) can force itself into a gap between the two supports (21, 42) which gap can arise during operation.