Captive Sprocket Retention for Independent Engine Accessory Removal
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Solution Overview
Problem
Current engine manufacturing processes require suboptimal assembly sequences, leading to significant labor and downtime costs when removing engine components like fuel pumps or air compressors, as they necessitate disassembly of the entire engine and chain assemblies.
Innovation Solution
A captive sprocket system with a retaining disc and captivation screws allows for the sprocket to be retained within a cylinder block, enabling the engine component to be removed without disassembling the flywheel housing or chain assemblies, by using a sprocket with a central opening for the drive shaft and configured to mesh with chain assemblies driven by the crankshaft and camshaft.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of repair
If the engine component is removed using conventional methods, then the component can be removed from the engine, but the flywheel housing and chain assemblies must also be disassembled, resulting in significant labor and downtime costs
Solution Approach 1:
The sprocket is segmented into multiple independent parts: the sprocket body, retaining disc, and captivation screws. This segmentation allows the sprocket to be independently removable from the engine component, enabling component removal without disassembling the entire flywheel housing and chain assembly system.
Solution Approach 2:
The retaining disc and captivation screws are pre-installed on the sprocket before the sprocket is mounted to the engine component. This preliminary assembly creates a self-contained unit that can be easily removed from the engine component without requiring removal of the flywheel housing or chain assemblies.
2Strength
If the sprocket is permanently fixed to the engine component, then the component can be securely driven, but the component cannot be removed without removing the entire chain system and flywheel housing
Solution Approach 1:
The mounting system transitions from a permanent fixed connection to a dynamic, reversible connection. The captivation screws can be removed to detach the sprocket from the engine component, allowing the component to be freely removed and reinstalled as needed, changing the mounting state from static to dynamic.
Solution Approach 2:
The retaining disc provides localized support and positioning at the center of the sprocket, while the captivation screws provide localized securing at four points around the retaining disc. This distributed local quality approach ensures secure mounting while maintaining ease of removal.
3Ease of repair
If the sprocket is designed with a retaining disc and captivation screws, then the sprocket can be retained within the cylinder block, but the device complexity increases
Solution Approach 1:
The sprocket system is divided into separable components: the sprocket body, retaining disc, and captivation screws. This segmentation allows each component to be independently manufactured and assembled, simplifying the overall system while enabling easy removal of the engine component without disassembling the entire chain system.
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.