Plunger Stopper Nesting in High Pressure Pump Cylinder

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Solution Overview

Problem

Existing high pressure fuel pumps face issues with plunger fall-off during assembly and installation, and exposure of slide surfaces can lead to damage and malfunction due to contact with stoppers or foreign objects, particularly in designs like JP2008-525713A and JPH04-231673A.

Innovation Solution

A high pressure pump design featuring a plunger stopper that cooperates with a step portion of the plunger to limit movement, ensuring the slide surface remains protected within the cylinder hole and preventing exposure, thus preventing damage and malfunction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a stopper structure is used to limit plunger movement, then plunger fall-off is prevented, but the slide surface becomes exposed and vulnerable to damage

Engineering Contradiction:

Improveplunger retentionVSAvoidslide surface damage

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The stopper is nested inside the cylinder hole, with its protrusion extending into the cylinder hole to contact the plunger's step portion. This nested configuration allows the stopper to limit plunger movement while remaining concealed within the cylinder hole, preventing exposure of the plunger's slide surface to external damage or foreign object adhesion.

Inventive Principle:

Principle #7Nested doll (Nesting)

2Reliability

If the stopper is positioned at the cylinder end, then plunger movement is limited, but the slide surface is exposed from the cylinder hole

Engineering Contradiction:

Improvemovement limitationVSAvoidslide surface protection

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The stopper is nested inside the cylinder hole rather than positioned at the external end. The protrusion of the stopper extends into the cylinder hole to contact the plunger, creating a nested arrangement that limits plunger movement while keeping the stopper concealed within the cylinder hole structure, thereby protecting the slide surface.

Inventive Principle:

Principle #7Nested doll (Nesting)

3Reliability

If a circlip is used to limit plunger movement, then falling off is prevented, but the slide surface is exposed and may be damaged

Engineering Contradiction:

Improveplunger retentionVSAvoidforeign object adhesion

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The stopper is nested inside the cylinder hole with its protrusion contacting the plunger from within the cylinder hole. This nested configuration prevents plunger fall-off while keeping the stopper and plunger interface concealed within the cylinder hole, preventing foreign objects from adhering to the exposed slide surface.

Inventive Principle:

Principle #7Nested doll (Nesting)

Data Source

PatentUS9109560B2High pressure pump

Publication Date: 2015.08.18 DENSO CORP

AI summary

A plunger stopper is installed to a cylinder hole forming portion of a cylinder forming member. The plunger stopper cooperates with a step portion of a plunger to limit movement of the plunger in a state where a slide surface of the plunger contacts an inner peripheral wall surface of the cylinder hole.