Starter Device Coil Spring Axial Positioning
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Solution Overview
Problem
Existing starter devices for internal combustion engines in hand-held power tools have a complex configuration due to additional parts like pressure springs, leading to increased weight and size, which is undesirable for minimalistic designs.
Innovation Solution
The starter device employs a coil spring positioned between the drive and output elements with abutments having varying radial spacings to manage axial length changes during rotation, eliminating the need for additional parts and optimizing the coil spring's position for minimal size and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pressure spring is added to prevent coil spring movement, then the coil spring is secured against the drive element, but the number of parts increases and weight increases
Solution Approach 1:
The patent removes the pressure spring from the system entirely. Instead of adding a pressure spring to secure the coil spring, the invention uses the differential radial spacing of abutments (smaller spacing in radial outer area, larger spacing in radial inner area) to achieve the same securing function, thereby eliminating unnecessary parts and reducing weight
Solution Approach 2:
The patent combines the coil spring securing function with the existing abutment structure. The abutments serve dual purposes: they guide the coil spring during rotation and simultaneously secure it axially through their differential radial spacing, eliminating the need for a separate pressure spring component
2Reliability
If a pressure spring is added to prevent coil spring movement, then the coil spring is secured against the drive element, but the device complexity increases
Solution Approach 1:
The patent extracts and removes the pressure spring component from the system. The coil spring securing function is achieved through the differential radial spacing of existing abutments, reducing the number of parts and simplifying the device structure
Solution Approach 2:
The abutments are designed with differential radial spacing to perform multiple functions: guiding the coil spring during rotation, limiting axial play, and securing the coil spring in its operative position. This multi-functionality eliminates the need for separate pressure spring components
3Ease of operation
If the abutments have uniform spacing, then the coil spring can move axially during rotation, but the axial position of the coil spring cannot be limited
Solution Approach 1:
The patent applies different radial spacings to different radial areas of the abutments. The radial outer area has smaller spacing to limit axial play and secure the coil spring, while the radial inner area has larger spacing to allow sufficient rotation freedom. This local differentiation achieves both requirements simultaneously
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 simplifies the starter device, reduces weight, and minimizes size by using fewer parts, effectively compensating for coil spring length changes through differential radial spacings, ensuring efficient operation and compactness for hand-held power tools.
Implementation Method 1
A coil spring (13) is arranged between the drive element (9) and the output element (18) in operative connection... the abutments... in a radial outer area at a different spacing to one another than in a radial inner area... compensating for coil spring length changes
Data Source
AI summary
A starter device for an internal combustion engine has a drive element and a output element. The drive element enables driving the starter device in rotation. The output element is supported rotatably about an axis of rotation and has a coupling device for releasably coupling the starter device to the crankshaft. A coil spring is arranged operatively between drive element and output element in an axial direction between a first abutment at the drive element and a second abutment at the output element. The first and second abutments have a first spacing relative to one another at least at one circumferential location in a first area and a second spacing relative to one another in a second area. The first and second spacing are measured parallel to the axis of rotation. The first spacing is smaller than the second spacing. The first area is radially outside of the second area.