Internal Gear Pump Saltwater Rust Prevention

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Solution Overview

Problem

Internal gear pumps experience reduced capacity efficiency due to saltwater ingress causing rusting between the housing and plate, leading to increased side clearance and reduced performance.

Innovation Solution

A pump design featuring an O-ring groove and discharge recess around the pump chamber formation surface, allowing rainwater to rinse off salt and prevent rusting, thereby maintaining close contact between the housing and plate and minimizing side clearance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the pump operates in a saltwater environment, then the pump can function in marine applications, but saltwater enters between the housing and plate causing rusting and increasing side clearance which reduces capacity efficiency

Engineering Contradiction:

Improvemarine application capabilityVSAvoidcapacity efficiency

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The pump chamber formation surface is segmented by forming a discharge recess that divides the surface into functional zones. This segmentation creates a dedicated drainage pathway that separates the sealing surface area from the saltwater accumulation zone, allowing saltwater to be discharged while maintaining the sealing function of the O-ring groove and close contact surface.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The discharge recess extracts and removes saltwater from the interface between the housing and plate by providing a dedicated drainage pathway. This extraction prevents saltwater from remaining in contact with the sealing surfaces, thereby preventing rusting and maintaining capacity efficiency in marine environments.

Inventive Principle:

Principle #2Taking out (Extraction)

2Reliability

If a discharge recess is formed in the pump chamber formation surface, then saltwater can be rinsed off and rusting prevented, but the area of close contact surface between housing and plate is reduced

Engineering Contradiction:

Improverust preventionVSAvoidclose contact surface area

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The pump chamber formation surface is designed with local quality variations: the discharge recess provides drainage functionality in specific zones while the O-ring groove and close contact surfaces maintain their sealing quality in other zones. This localized functional differentiation allows saltwater discharge without compromising the overall sealing performance.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The discharge recess converts the potentially harmful presence of saltwater into a beneficial drainage flow. By providing a controlled pathway for saltwater to exit, the design transforms saltwater from a rust-causing contaminant into a flow that actively rinses and cleans the sealing surfaces, then discharges away from the pump.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Reliability

If the O-ring groove is formed around the pump chamber, then the O-ring can seal the pump chamber, but saltwater can still enter between the housing and plate

Engineering Contradiction:

Improvepump chamber sealingVSAvoidsaltwater ingress

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The sealing system is segmented into two functional zones: the O-ring groove provides primary sealing around the pump chamber, while the discharge recess provides secondary drainage functionality. This segmentation allows the O-ring to maintain chamber sealing while the discharge recess handles saltwater removal from the housing-plate interface.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The discharge recess acts as an intermediary element between the sealed pump chamber and the external environment. It provides a controlled pathway that allows saltwater to be discharged from the housing-plate interface without compromising the O-ring seal of the pump chamber, thus mediating between sealing requirements and drainage needs.

Inventive Principle:

Principle #24Intermediary (Mediator)

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

The design effectively prevents rusting and maintains capacity efficiency by ensuring saltwater is rinsed off, reducing the force of rust and minimizing side clearance, even under saltwater spray tests, thus enhancing pump performance.

Implementation Method 1

an O-ring (14) placed in an O-ring groove (11i) formed around a pump chamber (11b) in a pump chamber formation surface (11f) of the housing (11) so as to close the pump chamber (11b)

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

salt water such as seawater enters between the housing and the plate from the outside due to capillary action

Methodology Applied

Scientific EffectCapillary action: Capillary Action

Data Source

PatentUS9745977B2Pump

Publication Date: 2017.08.29 JTEKT CORP

AI summary

A pump includes: a housing in which a pump chamber accommodating an inner rotor and an outer rotor is formed in a pump chamber formation surface, and an O-ring groove is formed around the pump chamber; an O-ring that is placed in the O-ring groove; and a plate that is attached to the pump chamber formation surface and closely contacts the O-ring to close the pump chamber. Inter-hole grooves connecting to an outer edge of the pump chamber formation surface are formed around the O-ring groove.