Starting Device Drive Shaft Length Reduction via Plastic Deformation
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Solution Overview
Problem
Existing starter devices require unnecessarily long drive shafts and high-mass components, leading to excessive impact forces on the sprocket due to the use of hardened stop rings, which are expensive and inefficient.
Innovation Solution
A starting device with a drive end shield and a bearing that supports a drive shaft, featuring a snap ring with a plastic deformation collar that prevents axial displacement, allowing for secure torque transmission without the need for hardened stop rings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a hardened stop ring is used to secure the locking ring, then high loads can be absorbed, but the cost increases significantly and the drive shaft length increases
Solution Approach 1:
The patent changes the material parameter from hardened steel to soft steel, and changes the geometric parameter by adding a plastic deformation section with undercut to the collar. This allows the stop ring to achieve the necessary load absorption capability through plastic deformation and undercut geometry rather than through hardened material, thereby reducing manufacturing cost while maintaining strength
Solution Approach 2:
The patent creates a composite structure by combining soft steel material with a plastic deformation section that forms an undercut. This composite approach (soft material + geometric feature) replaces the need for fully hardened steel, achieving both cost reduction and sufficient load absorption capability
2Strength
If a hardened stop ring is used to secure the locking ring, then high loads can be absorbed, but the drive shaft length increases
Solution Approach 1:
The patent changes the material parameter from hardened steel to soft steel, and changes the geometric parameter by adding a plastic deformation section with undercut to the collar. This allows the stop ring to achieve the necessary load absorption capability through plastic deformation and undercut geometry rather than through hardened material, thereby reducing manufacturing cost while maintaining strength
Solution Approach 2:
The patent extracts the essential function of the stop ring (preventing axial displacement through undercut engagement) from the hardened material property. By separating the geometric feature (undercut) from the material property (hardening), the design achieves the necessary function with softer, cheaper material and shorter dimensions
3Reliability
If a sleeve-like stopper is used to hold the locking ring, then the locking ring can be secured against centrifugal load, but the drive shaft requires unnecessary length
Solution Approach 1:
Instead of using a sleeve-like stopper that extends axially to hold the locking ring (conventional approach), the patent inverts the approach by having the collar itself form the retaining structure through plastic deformation. The undercut in the plastic deformation section engages with the locking ring, eliminating the need for an extended sleeve-like structure and reducing drive shaft length while maintaining locking reliability
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 design reduces the length of the drive shaft, minimizes unnecessary mass, and lowers impact forces on the sprocket while providing cost-effective and efficient torque transmission.
Implementation Method 1
The collar of the stop ring is plastically deformed. The collar has at least one plastic deformation on its circumference.
Data Source
AI summary
The device has a drive end bearing housing (19) in which a bearing (122) e.g. ball bearing, is fixed. The bearing indirectly supports a drive shaft (142). A starting pinion (22) is fastened to the drive shaft such that torque is transferable from the drive shaft to the starting pinion. The starting pinion has a front side (203), which is provided away from a drive of the device. A securing clip (209) i.e. snap ring, is stationary arranged on the drive shaft. A stopper ring (218) overlaps the securing clip by a single-piece formed collar (220) that is plastically deformed.