Captive Engine Sprocket Assembly for Easier Component Removal

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Solution Overview

Problem

Existing engine assembly and maintenance processes require disassembly of the flywheel housing and chain assemblies to remove engine components like fuel pumps or air compressors, leading to significant labor and downtime.

Innovation Solution

A sprocket system with a retaining disc and captivation screws that allows the engine component to be retained within the cylinder block, enabling removal without disassembling the flywheel housing or chain assemblies.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the engine component is installed prior to installing the chain system and flywheel housing, then the assembly sequence is optimized, but the component cannot be removed without disassembling the flywheel housing and chain assemblies

Engineering Contradiction:
Improveassembly sequenceVSAvoidcomponent removal
Core Design Contradiction:
Ease of manufactureVSEase of repair

Solution Approach 1:

The sprocket assembly is segmented into multiple functional parts: the sprocket body with gears, a retaining disc for axial positioning, and multiple captivation screws for radial securing. This segmentation allows the component to be installed in an optimized sequence while enabling independent removal of the engine component without disassembling the flywheel housing or chain assemblies, as the captivation screws can be independently accessed and removed.

Inventive Principle:
Principle #1Segmentation

2Reliability

If the sprocket is securely retained in the bore, then the reliability of power transmission is improved, but the complexity of the retention mechanism increases

Engineering Contradiction:
Improvepower transmissionVSAvoidretention mechanism
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The retention mechanism merges multiple functions into a unified structure: the retaining disc combines axial positioning with radial location features, while the captivation screws serve both as mounting fasteners and as access points for component removal. This merging provides reliable power transmission through secure retention while avoiding excessive complexity by using straightforward mechanical elements rather than complex locking or adjustment mechanisms.

Inventive Principle:
Principle #5Merging (Combining)

Data Source

PatentEP3797219B1System and method for a captive sprocket in an engine
Publication Date: 2026.04.08 CUMMINS INC
  • EP3797219B1 patent drawingFigure 1
  • EP3797219B1 patent drawingFigure 2
  • EP3797219B1 patent drawingFigure 3A~3B

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.