Fusing Unit Duct with Cul-de-sac for UFP Trapping
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Solution Overview
Problem
Conventional image forming apparatuses fail to adequately suppress the emission of ultrafine particles (UFPs) derived from silicone rubber in the fusing unit, which are released into the air and pose a challenge for further reduction.
Innovation Solution
An image forming apparatus with a duct system that includes an inlet and exhaust outlet, a blowing unit to direct air flow, and a cul-de-sac within the duct to enhance UFP trapping, utilizing the Coanda effect and turbulence to adhere particles to the duct walls, thereby reducing the amount of UFPs released outside the apparatus.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a conventional duct system is used to discharge air from the fusing unit, then the structure is simple, but ultrafine particles are released into the environment
Solution Approach 1:
The duct is segmented into multiple functional regions: an introduction channel for air intake, a main channel for air flow, and a cul-de-sac for particle trapping. This segmentation allows each section to perform a specific function, with the cul-de-sac specifically designed to trap UFPs while other sections handle air flow, thereby reducing overall emissions without requiring a completely complex new system design.
Solution Approach 2:
The cul-de-sac acts as an intermediary trap within the duct system. Air containing UFPs flows through the introduction channel and main channel, and the cul-de-sac intercepts and traps these particles before the air is discharged. This intermediary structure allows the system to maintain simple overall architecture while effectively reducing UFP emissions through the trapping mechanism.
2Object-affected harmful factors
If air flow is increased to remove particles, then particle removal efficiency improves, but energy consumption increases
Solution Approach 1:
The system converts the harmful high-velocity air flow that would otherwise directly carry particles outside into a beneficial force. The high-velocity flow from the blowing unit is directed through the cul-de-sac, where it creates turbulence and pressure changes that cause particles to adhere to the walls. The same air flow that could harmfully transport particles is thus converted into a mechanism that traps them, reducing energy consumption compared to continuous high-velocity discharge.
Solution Approach 2:
The system changes the flow parameters within the cul-de-sac region. As air enters the cul-de-sac from the main channel, the flow velocity and pressure distribution change, creating conditions favorable for particle trapping. The cul-de-sac geometry causes the air flow to slow down and create recirculation zones, changing the parameters from high-velocity transport to low-velocity trapping, thereby improving particle removal efficiency without proportionally increasing energy consumption.
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 described configuration effectively reduces UFP emission by two times compared to conventional systems, as demonstrated through measurements, by utilizing the duct's design to trap particles within the cul-de-sac and filter, minimizing their release into the environment.
Implementation Method 1
a blowing unit for causing a current of air toward the exhaust outlet within the duct
Implementation Method 2
utilizing the Coanda effect and turbulence to adhere particles to the duct walls
Implementation Method 3
utilizing the Coanda effect and turbulence to adhere particles to the duct walls
Data Source
AI summary
An image forming apparatus has a fusing unit including a first rotor provided with a heat-generating unit and an elastic layer, as well as a second rotor provided in direct contact with the first rotor, the fusing unit fixing a toner image on a sheet, and a duct for allowing an inlet and an exhaust outlet to communicate with each other, the inlet being adapted to allow a current of air derived from the fusing unit to flow in, the exhaust outlet facing toward the outside of the apparatus. The duct includes an introduction channel for guiding and jetting out air taken in from the inlet, a main channel for guiding the air jetted out of the introduction channel to the exhaust outlet, and a cul-de-sac provided in communication with the main channel at one end and closed at the other end.