Liquid Pump Gas Accumulation Area for Cavitation Prevention

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Solution Overview

Problem

Conventional liquid pumps in Rankine cycle systems are prone to damage due to cavitation and the introduction of gas-liquid two-phase states, leading to inconsistent output and vibrations, and require complex pressure and temperature sensors to prevent damage, increasing manufacturing costs.

Innovation Solution

A liquid pump design featuring a casing with a suction space that includes a gas accumulation area above the feed pipe opening, separating gas from liquid and preventing gas from entering the pump mechanism, along with a discharge space to manage pulsations and a shaft for adjusting liquid flow, ensuring only liquid reaches the pump mechanism.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional liquid pumps are used in Rankine cycle systems, then the pump can operate with liquid working fluid, but gas may enter the pump mechanism causing cavitation and component damage

Engineering Contradiction:
Improvepump reliabilityVSAvoidgas introduction and cavitation
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The suction chamber is segmented into a gas accumulation area and a liquid suction area by a partition wall. This segmentation prevents gas from mixing with the liquid suction, ensuring that only liquid enters the pump mechanism while gas is directed to the discharge side, thereby preventing cavitation and component damage.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The partition wall acts as an intermediary structure between the gas accumulation area and the liquid suction area. It selectively allows liquid to pass through to the suction hole while blocking gas, serving as a mediator that separates the harmful gas phase from the pump mechanism.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If pressure sensors and temperature sensors are installed to detect cavitation and adjust pump output, then pump damage can be prevented, but the device complexity and manufacturing cost increase

Engineering Contradiction:
Improvepump damage preventionVSAvoidsensor system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The pump system performs self-protection by using the partition wall to automatically separate gas from liquid at the suction side. This passive structural design eliminates the need for active sensor-based control systems, reducing device complexity while maintaining reliability through inherent gas-liquid separation.

Inventive Principle:
Principle #25Self-service

3Productivity

If a suction chamber is disposed beneath the suction part, then liquid suction is improved, but gas accumulation may occur affecting pump performance

Engineering Contradiction:
Improveliquid suction efficiencyVSAvoidgas accumulation
Core Design Contradiction:
ProductivityVSObject-affected harmful factors

Solution Approach 1:

The suction chamber is segmented into distinct gas and liquid zones using a partition wall. The liquid suction area maintains its position for efficient liquid intake, while the gas accumulation area is separated and directed away from the suction hole, allowing both functions to operate simultaneously without interference.

Inventive Principle:
Principle #1Segmentation

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 enhances pump reliability by preventing gas from entering the pump mechanism, reducing the risk of cavitation and maintaining consistent output, while simplifying the system configuration and reducing manufacturing costs by eliminating the need for complex sensors.

Implementation Method 1

a gas accumulation area which accumulates the gas brought into the casing through the feed pipe together with liquid to separate the gas from the liquid

Methodology Applied
Scientific EffectGas accumulation and separation: Density Gradient

Data Source

PatentEP2937569B1Liquid pump and rankine cycle device
Publication Date: 2019.05.15 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD
  • EP2937569B1 patent drawingFigure 1
  • EP2937569B1 patent drawingFigure 2
  • EP2937569B1 patent drawingFigure 3

AI summary

A liquid pump includes: a casing (10); a feed pipe (21) bringing liquid from outside the casing (10) to inside the casing (10); a pump mechanism (12) provided in the casing (10) and including a suction hole (22) for sucking in the liquid and a discharge hole (23) for discharging the liquid sucked in via the suction hole (22); a suction space (19) positioned in the casing (10) on a suction-hole inlet side (22i) and making a flow path formed by the feed pipe (21) and the suction hole (22) communicate with each other; and a discharge space (18) positioned on a discharge-hole outlet side (23o) in the casing (10) and communicating with the discharge hole (23). The suction space (19) includes a gas accumulation area (19c) that is positioned above a center (21c) of an opening at casing-side end of the feed pipe (21), when viewed vertically and that accumulates gas brought into the casing (10) through the feed pipe (21) together with the liquid to separate the gas from the liquid.