Freewheel Gear Countersunk Guide Unit Axial Play Reduction
Solution Overview
Problem
In existing starters for internal combustion engines, the axial play in freewheel gears leads to axial forces being transmitted radially, causing self-locking and freewheel slipping, resulting in functional failures due to the deformation of softer guide disks and retaining disks under assembly pressure.
Innovation Solution
A freewheel gear design where the guide unit is countersunk in the face geometry, reducing its tolerance contribution and eliminating the erecting effect during assembly, allowing a shorter closure cap and weight savings, with the guide unit not being directly contacted by the locking cap, thus preventing force transmission to the guide disk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the guide unit is arranged between the axial limit and outer part without countersinking, then the assembly is simpler, but the axial play increases and the guide disk deforms under assembly pressure
Solution Approach 1:
The guide unit is countersunk into a corresponding recess in the outer part, creating a nested arrangement where the guide unit is partially received within the outer part. This nesting reduces the guide unit's contribution to the tolerance chain and prevents deformation under assembly pressure while maintaining assembly simplicity.
2Force
If the closure cap is made longer to contact the guide unit, then force transmission is improved, but the guide disk deforms and axial play increases
Solution Approach 1:
The closure cap is designed to contact only specific local areas - the axial limit and the outer part - while deliberately avoiding contact with the guide unit. This localized contact strategy transmits assembly forces through harder components without deforming the softer guide disk, preventing axial play increase and functional failures.
3Length of moving object
If the guide unit is not countersunk, then the closure cap can be longer, but weight increases and the erecting effect occurs
Solution Approach 1:
The guide unit is extracted from the main assembly path by countersinking it into the outer part, removing it from the force transmission path. This allows the closure cap to be shortened without compromising force transmission, as the force is now transmitted through the axial limit and outer part rather than through the guide unit.
4Ease of operation
If the closure cap contacts the guide unit during assembly, then assembly is easier to monitor, but the guide disk deforms and axial play increases
Solution Approach 1:
The patent employs a non-contact monitoring method during assembly, likely using optical or sensor-based detection to monitor the assembly process without physical contact. This allows assembly monitoring while preventing force transmission to the guide unit that would cause deformation and axial play.
Data Source
Figure 1
Figure 2
AI summary
The device (100) has a freewheel gear box (33) arranged on forehead geometry of an axial confinement. A guide unit is provided in forehead geometry of an outer part and a sinking part e.g. inner recess, ribs, slots and grooves. An outer rim is connected with the guide unit. A closure cap is provided on the axial confinement, the guide unit and the outer part. Outer dimension of the guide unit is less than that of the outer part. An independent claim is also included for a method for manufacturing a turning device.