Starter Pinion Retention via Elastic Ring
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Solution Overview
Problem
Conventional heat engine starters with outgoing pinions for motor vehicles have a high number of parts and axial bulk, which increases complexity and susceptibility to centrifugal forces, limiting the pinion's size and teeth count.
Innovation Solution
A heat engine starter design featuring a centrally perforated pinion with an elastic ring for axial immobilization, where the elastic ring is housed in a recess and mounted in a groove, reducing the number of parts and axial bulk, and preventing ejection due to centrifugal forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional starters use multiple parts (abutment, snap ring, cover, extra thickness) to retain the pinion, then the pinion is securely retained, but the axial bulk increases and the number of parts increases
Solution Approach 1:
The patent combines multiple retention functions into a single elastic ring component. The elastic ring simultaneously provides axial retention, radial retention, and centrifugal force resistance that previously required multiple separate parts (abutment, snap ring, cover). This merging reduces the number of parts while maintaining reliable pinion retention.
Solution Approach 2:
The elastic ring serves multiple functions: it acts as an abutment for axial retention, a snap ring for radial retention, and a centrifugal force-resistant component. This multi-functionality eliminates the need for separate components like the cover and extra thickness, reducing overall device complexity while maintaining retention reliability.
2Reliability
If conventional starters use multiple parts and extra thickness to retain the pinion, then the pinion is securely retained, but the axial bulk increases
Solution Approach 1:
The patent merges the functions of multiple axial retention components (abutment, cover, extra thickness) into the single elastic ring. This eliminates the need for additional axial space that would be required for separate components, thereby reducing axial bulk while maintaining secure pinion retention.
Solution Approach 2:
The elastic ring utilizes the radial dimension more effectively by expanding outward to engage with the pinion's outer periphery. This radial engagement provides retention without requiring additional axial space, thus reducing axial bulk while maintaining retention reliability.
3Productivity
If the pinion is made larger with more teeth, then the starter performance improves, but the pinion becomes more susceptible to centrifugal forces
Solution Approach 1:
The patent changes the material parameter of the retention component from rigid (metal abutment and snap ring) to elastic. The elastic ring can deform to accommodate centrifugal forces acting on a larger pinion with more teeth, while still maintaining retention. This parameter change allows the pinion to be made larger without being overly susceptible to centrifugal forces.
Solution Approach 2:
The elastic ring provides dynamic retention that can adapt to varying centrifugal forces. As the pinion rotates at higher speeds with more teeth, the elastic ring deforms to accommodate the increased centrifugal forces while maintaining retention, unlike rigid components that would require additional restrictive features.
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 simplifies assembly, increases the pinion's size and teeth count, enhances reliability, and maintains resistance while reducing axial bulk, allowing for higher speed operation and improved performance.
Implementation Method 1
the abutment is constituted by an elastic ring of height greater than its thickness
Implementation Method 2
preventing ejection due to centrifugal forces
Data Source
Figure 1~2
Figure 3~5
AI summary
The combustion engine starter with output pinion (18) comprises a front bearing (12) provided with a front face (120) having an opening (312), a drive assembly equipped with a bush (26) passing through the opening (312) and bearing the output pinion (18) outside the front bearing (12), complementary splines (67,167) which act between the front end of the bush (26) and at the internal periphery of the output pinion (18), a groove (64, 164) which interrupts the splines (67) of the bush (26) in order to mount a stop (60, 160) for immobilizing the pinion, a play-compensating spring (61) urging the pinion into contact with the stop (60, 160) formed by a spring ring which has a height greater than its thickness and which is housed with radial clearance at least partially in an annular recess (62) made in the front face (183) of the pinion (18); the internal periphery of the spring ring (60, 160) being mounted in the groove (64, 164) in the bush (26). Application: combustion engine starter of a motor vehicle.