Engine Starting Device Ignition Switch Rattling Prevention
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Solution Overview
Problem
Conventional engine starting devices with press-fit ribs around the periphery of the ignition switch fail to completely prevent displacement and resulting rattling, leading to imperfect rattling prevention.
Innovation Solution
The engine starting device incorporates a housing with an ignition switch that uses snap-locking portions on both the fitting start and finish ends to prevent rattling by forming pressure contact with the peripheral wall surfaces, with ribs on the ignition switch and attachment recess positioned to avoid continuity and coincidence, ensuring simultaneous pressure contact at both ends during fitting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If press-fit ribs are disposed on a single circle around the periphery of the ignition switch, then the structure is simple, but displacement in the fitting direction cannot be completely prevented resulting in imperfect rattling prevention
Solution Approach 1:
The press-fit ribs are segmented into two separate circles: a first circle on the fitting start end side and a second circle on the fitting finish end side. This segmentation allows pressure contact to be distributed at both ends of the ignition switch, preventing displacement in the fitting direction more effectively than a single circular arrangement while maintaining structural simplicity.
Solution Approach 2:
The invention transitions from a single-dimensional (single circle) pressure contact arrangement to a two-dimensional distribution of pressure contact points along the axial direction of the ignition switch. By placing press-fit ribs at both the fitting start end and fitting finish end, the pressure contact is extended along the axial dimension, effectively preventing rattling without significantly increasing complexity.
2Ease of manufacture
If press-fit ribs are disposed on a single circle around the periphery of the ignition switch, then manufacturing is easier, but fitting precision is insufficient leading to displacement and rattling
Solution Approach 1:
The press-fit ribs are divided into two separate groups located at different axial positions (fitting start end and fitting finish end). This segmentation enables precise positioning at both ends of the ignition switch, ensuring accurate fitting without requiring complex single-circle rib arrangements, thus maintaining ease of manufacture while improving fitting precision.
Solution Approach 2:
The press-fit ribs at the fitting start end side engage with the attachment recess first during the fitting process, establishing preliminary pressure contact that guides and stabilizes the ignition switch as it is being inserted. This preliminary action ensures proper alignment and positioning before the final engagement at the fitting finish end, improving overall fitting precision.
3Reliability
If pressure contact is applied at both fitting ends simultaneously, then rattling is effectively prevented, but fitting force increases
Solution Approach 1:
The press-fit ribs at the fitting start end side engage first during insertion, providing preliminary pressure contact that stabilizes the ignition switch early in the fitting process. This preliminary action prevents rattling from the beginning, reducing the need for excessive fitting force to eliminate vibrations, while the second circle of ribs at the finish end completes the secure engagement.
Data Source
Figure 1(a)~1(c)
Figure 2(a)~2(d)
Figure 3(a)~3(d)
AI summary
An object of the present invention is to provide an engine starting device which can prevent rattling of an ignition switch in a coupled state. Provided is an engine starting device including: a housing 2 accommodating a rotational operation shaft 1; and an ignition switch 3 coupled to the housing 2 and configured to be actuated upon application of rotational operation force to the rotational operation shaft 1. The ignition switch 3 is fitted and held in an attachment recess 4 formed in the housing 2, in such a way as to be prevented from falling from the attachment recess 4 by appropriate snap-locking portion 5. The peripheral wall surfaces of the ignition switch 3 and the attachment recess 4 on the fitting start end side and the peripheral wall surfaces thereof on the fitting finish end side come into pressure contact with each other substantially simultaneously with each other when the depth of the fitting of the ignition switch 3 to the attachment recess 4 reaches a predetermined depth, to thereby reduce rattling in the radial direction.