Combustion Engine Starter Coupling Layout for Compact Axial Space
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing starting devices for combustion engines have complex constructions that occupy valuable axial space, making them less ergonomic and usable in handheld work apparatuses.
Innovation Solution
A starting device with a first coupling unit that creates a rotationally conjoint connection between the rope pulley and spring housing during starting, acting as a freewheel in the opposite direction, allowing the tension spring to be tightened over multiple starts, and featuring coupling elements with a radial spacing to the rotational axis, reducing the device's axial size by allowing the spring housing to be positioned closer to the rope pulley.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the coupling unit is arranged close to the rotational axis in the structural space formed between rope pulley and spring receiving space, then the starting device has a compact radial design, but the axial structural space is increased making the device less ergonomic for handheld work apparatuses
Solution Approach 1:
The coupling unit is repositioned from a radial arrangement (close to rotational axis) to an axial arrangement (at the end of spring receiving space). This dimensional shift moves the coupling elements along the axial direction, allowing the spring housing to be positioned closer to the rope pulley axially, thereby reducing the overall axial structural space while maintaining radial compactness.
2Force
If the coupling elements are dimensioned to transmit predefined torque with large lever arm, then the torque transmission capability is sufficient, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The design optimizes the lever arm length of coupling elements to a specific range (5mm to 15mm) that provides sufficient torque transmission capability while avoiding excessive complexity. The contact location is positioned at the end of the spring receiving space, creating an optimal lever arm that balances torque requirements with manufacturing simplicity and compactness.
3Reliability
If the spring housing is positioned farther from the rope pulley to accommodate the coupling unit, then the coupling elements can interact properly, but the axial structural space is increased reducing ergonomics
Solution Approach 1:
The coupling unit is nested within the axial space at the end of the spring receiving space, allowing the spring housing to be positioned as close as possible to the rope pulley. The coupling elements are arranged to interact within the available axial space, with the first coupling element on the spring housing and the second coupling element on the rope pulley, creating a compact nested arrangement that maintains reliable coupling interaction while minimizing axial length.
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 results in a compact, simplified construction that saves axial space, enhancing the ergonomic handling and usability of handheld work apparatuses by reducing the structural size while maintaining the ability to transmit a predefined torque.
Implementation Method 1
a tension spring (40) which is arranged in a spring housing (7) and acts on the entrainer (8)
Implementation Method 2
US 2002/0121258 has disclosed a starting device for a combustion engine. The starting device has a spring store which has a spiral spring arranged in an inner housing
Data Source
AI summary
A starting device for a combustion engine includes a housing relative to which a rope pulley, a spring housing and an entrainer can rotate about a rotation axis. A coupling unit produces a rotationally-fixed connection between the rope pulley and the spring housing in response to a rotational movement of the rope pulley in a starting direction. The spring housing has a spring receiving space for a tension spring and is connected to an entrainer by the spring. The coupling unit has a first coupling element and a second coupling element, which interact at a contact location which is at a spacing (d) to the rotation axis and is at least as large as the maximum spacing (c) of the tension spring to the rotation axis.