Liquid Discharge Pressure Control for Precise Bubble-Free Ejection

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Solution Overview

Problem

Existing liquid discharge methods using syringes struggle with maintaining discharge pressure, continuous discharge, and controlling discharge amounts, while solenoid valve-based methods risk air bubble generation and contamination, and require sealing structures that complicate cleaning and system downtime.

Innovation Solution

A liquid discharge device utilizing a pump, pressure sensor, discharge solenoid valve, and control unit to maintain constant pressure and control discharge amount by adjusting the solenoid valve opening and closing times, with a flexible container and closed-system flow path to minimize contamination and system size.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a solenoid valve is opened and closed for a certain time to control discharge amount, then discharge control is achieved, but air bubbles are generated and liquid quality deteriorates

Engineering Contradiction:

Improvedischarge amount controlVSAvoidair bubble generation

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The patent uses a peristaltic pump to generate liquid flow through rhythmic compression and relaxation of tubing, eliminating the need for solenoid valve opening/closing operations. This hydraulic approach maintains continuous liquid flow without air bubble generation while achieving precise discharge control through pump speed and compression force regulation.

Inventive Principle:

Principle #29Pneumatics and hydraulics

Solution Approach 2:

The patent replaces the mechanical solenoid valve opening/closing mechanism with a peristaltic pumping mechanism. The peristaltic pump uses controlled mechanical compression of elastic tubing to propel liquid forward, substituting the solenoid valve's intermittent opening/closing action with continuous rhythmic compression, thereby preventing air bubble entrainment.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Stress or pressure

If a sealing structure with pressure resistance is used to store liquid, then pressure maintenance is improved, but cleaning becomes difficult and system downtime increases

Engineering Contradiction:

Improvepressure maintenanceVSAvoidcleaning accessibility

Core Design Contradiction:

Stress or pressureVSEase of repair

Solution Approach 1:

The patent uses flexible elastic tubing as the liquid containment structure instead of rigid sealed tanks. The tubing can be easily disconnected, removed, and cleaned without disassembling complex sealing structures. The elastic material maintains pressure through its inherent elasticity while allowing rapid access for cleaning by simply detaching the tubing from the pump.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The liquid containment system is segmented into discrete sections of tubing that can be independently removed and cleaned. Rather than a single large sealed tank requiring complex disassembly, the system uses multiple short tubing sections that can be quickly detached and cleaned separately, dramatically reducing system downtime.

Inventive Principle:

Principle #1Segmentation

3Productivity

If compressed air is constantly applied to the liquid tank, then liquid discharge is maintained, but contamination risk increases

Engineering Contradiction:

Improvecontinuous dischargeVSAvoidcontamination risk

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent uses a peristaltic pump to generate liquid discharge through rhythmic mechanical compression of the tubing, replacing the need for compressed air application. This hydraulic pumping action maintains continuous liquid flow without introducing compressed air into the system, thereby eliminating the contamination risk associated with air-liquid contact.

Inventive Principle:

Principle #29Pneumatics and hydraulics

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 solution provides improved processing efficiency by maintaining consistent discharge pressure, reducing contamination risk, and allowing rapid system recovery from pollution, while minimizing system size and cost.

Implementation Method 1

a peristaltic pump which feeds the liquid

Methodology Applied

Scientific EffectPeristalsis: Peristalsis

Implementation Method 2

a pressure sensor which detects liquid pressure

Methodology Applied

Scientific EffectPressure sensing: Pressure Gradient

Implementation Method 3

a discharge solenoid valve which controls discharge of the liquid in the discharge unit

Methodology Applied

Scientific EffectElectromagnetic actuation: Electromagnet

Data Source

PatentEP4644699A1Liquid ejection device

Publication Date: 2025.11.05 HITACHI HIGH TECH CORP

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AI summary

Performance of a liquid discharge device that performs discharge a liquid by a constant amount is improved. As a method thereof, used is a liquid discharge device including: a pump configured to feed a liquid; a discharge unit configured to discharge the liquid; a pressure sensor configured to monitor a pressure of the liquid; a discharge solenoid valve configured to control discharge of the liquid in the discharge unit; a control unit configured to control the pressure of the liquid to be constant; and a flow path of the liquid that connects the pump, the discharge unit, the pressure sensor, and the discharge solenoid valve to each other, in which a discharge amount of the liquid is controlled by an opening and closing time of the discharge solenoid valve in a state in which the pressure of the liquid is controlled to be constant by the control unit.