Captive Engine Sprocket Retention for Easier Component Removal
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Solution Overview
Problem
Existing engine assembly and maintenance processes require disassembly of the engine component driven by a sprocket, such as a fuel pump or air compressor, necessitating removal of the flywheel housing and chain assemblies, leading to significant labor and downtime costs.
Innovation Solution
A captive sprocket system comprising a sprocket with a retaining disc and captivation screws, allowing the sprocket to be retained within a cylinder block bore, enabling the engine component to be removed without disassembling the flywheel housing or chain assemblies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the sprocket is permanently fixed to the engine component, then the sprocket is securely retained, but the engine component cannot be removed without removing the flywheel housing and chain assemblies
Solution Approach 1:
The sprocket is divided into two functional parts: a retention portion that remains permanently mounted in the flywheel housing, and a drive portion that is removably coupled to the engine component. This segmentation allows the retention portion to stay fixed while the drive portion can be removed with the engine component, enabling easy maintenance without removing the entire flywheel housing.
Solution Approach 2:
The sprocket transitions from a static, permanently fixed configuration to a dynamic, selectively removable configuration. The removable coupling mechanism allows the drive portion to be detached from the engine component when needed, providing operational flexibility while maintaining secure retention during normal operation.
2Ease of repair
If the sprocket is made removable from the engine component, then maintenance is easier, but the sprocket may become loose or misaligned
Solution Approach 1:
By separating the sprocket into a permanently retained portion and a removably coupled drive portion, the system ensures that the retention portion remains securely fixed in the flywheel housing while the drive portion can be easily removed for maintenance. The permanent retention portion maintains alignment and prevents loosening issues.
Solution Approach 2:
The problematic retention function is extracted from the removable drive portion and placed in a separate, permanently fixed retention portion. This extraction ensures that the reliability-critical retention function is isolated from the maintenance-critical removable coupling, allowing easy maintenance without compromising retention reliability.
3Ease of operation
If the flywheel housing is made accessible for sprocket removal, then component maintenance is simplified, but the housing structure becomes more complex
Solution Approach 1:
The sprocket drive portion is extracted from the permanently fixed retention portion, allowing it to be removed independently through the flywheel housing. This extraction eliminates the need for complex disassembly of the housing structure, as only the removable drive portion needs to be accessed and removed.
Solution Approach 2:
The flywheel housing transitions from requiring complete disassembly for sprocket removal to allowing selective access for drive portion removal. The dynamic design of the removable coupling enables maintenance personnel to access and remove the drive portion through the existing housing structure without adding complex access mechanisms.
Data Source
AI summary
The present disclosure provides a captive sprocket system for an engine, comprising: a sprocket including a first sprocket gear, a second sprocket gear and a retaining disc having a diameter and a thickness; a cylinder block having a bore with a central opening and a plurality of threaded bosses, the plurality of threaded bosses together forming an axial support surface and a radial location surface, the axial support surface and the radial location surface being sized to receive the retaining disc of the sprocket to support and locate the sprocket; and a plurality of captivation screws configured to be received by the plurality of threaded bosses, each captivation screw having a head with a lower surface which, when the captivation screw is received by a threaded boss, overlies the retaining disc and retains the sprocket in the bore.