Liquid Tank Flow Path Design for Air Trapping Prevention
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Solution Overview
Problem
In liquid ejecting apparatuses, when multiple liquid tanks are used with a single pump, the flow rate of the liquid in the liquid-communication flow path decreases, leading to potential air trapping and ejection defects due to air flowing into the liquid supply section, causing issues like failure to eject liquid from the head.
Innovation Solution
A liquid tank design with a liquid-communication flow path that includes an upward and downward flow path, a narrow portion, and an air-communication flow path, where the air-communication flow path is coupled above the liquid-communication flow path, allowing air to flow into the air path and preventing it from reaching the liquid supply section, and the narrow portion helps maintain pressure loss and prevent air from entering the liquid supply section.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the sectional area of the liquid-communication flow path is reduced to compensate for decreased flow rate when multiple liquid tanks are used with a single pump, then the liquid supply efficiency is improved, but air (bubbles) is likely to be trapped in the flow path when the liquid tank is tilted
Solution Approach 1:
The liquid-communication flow path is segmented into multiple sections with different cross-sectional areas. The flow path includes a first section with a larger cross-sectional area and a second section with a smaller cross-sectional area, creating a stepped configuration that prevents air trapping while maintaining liquid supply efficiency
Solution Approach 2:
The flow path cross-sectional area is made asymmetric along the flow direction, with a stepped configuration where the area changes from larger to smaller. This asymmetric design creates a geometry that allows liquid to flow through efficiently while preventing air bubbles from being trapped in the narrower sections
2Speed
If the sectional area of the liquid-communication flow path is uniformly reduced, then liquid supply speed is improved, but air may flow toward the liquid supply section at an unexpected time during print processing
Solution Approach 1:
Different sections of the flow path are given different local qualities in terms of cross-sectional area. The first section has a larger area for efficient liquid supply, while the second section has a smaller area that acts as a barrier to air flow, creating localized functional zones within the flow path
3Ease of operation
If air enters the liquid supply section and moves to the liquid ejecting head, then liquid ejection function is maintained, but ejection defects occur such as failure to eject liquid
Solution Approach 1:
The narrowed second section of the flow path acts as an intermediary barrier between the liquid chamber and the liquid supply section. This intermediate section with smaller cross-sectional area prevents air bubbles from the liquid chamber from reaching the liquid supply section and ejecting head, while still allowing liquid to pass through
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
This design effectively prevents air from entering the liquid supply section, reducing the likelihood of ejection defects and ensuring stable liquid supply to the ejecting head, even when the tank is tilted or during print processing.
Implementation Method 1
a liquid-communication flow path that couples the liquid chamber and the liquid supply section, through which the liquid stored in the liquid chamber can be supplied to the liquid supply section
Implementation Method 2
The liquid-communication flow path has, at an intermediate position thereof, a narrow portion in which the sectional area of the liquid-communication flow path is small
Data Source
AI summary
A liquid tank includes: a liquid supply section; a liquid chamber; a liquid-communication flow path an air-communication flow path. The liquid-communication flow path has, in a liquid flow direction from the liquid chamber toward the liquid ejecting head: an upstream end coupled to the liquid chamber; an upward flow path located downstream of the upstream end and extending upward in the attached state; a downward flow path located downstream of the upward flow path and extending downward in the attached state; and a downstream end located downstream of the downward flow path and coupled to the liquid supply section and the air-communication flow path. The liquid-communication flow path has, at an intermediate position thereof, a narrow portion in which the sectional area of the liquid-communication flow path is small.