Dishwasher Air-Extraction Duct Layout for Compact Drying
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Solution Overview
Problem
Existing dishwashers with open-circuit drying systems are often complex and costly to produce, with challenges in compact design and efficient air extraction due to the placement and configuration of air extraction components.
Innovation Solution
A dishwashing machine with a compact air-extraction system featuring a radial fan and a discharge duct with a tapered shape, where the duct's intermediate portion decreases in height and increases in width towards the outlet, ensuring direct airflow and improved air change within the tub, while maintaining a compact and flexible design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the air extraction system is placed in the door of the machine, then the damp air can be extracted from the tub, but the construction of the machine becomes complicated
Solution Approach 1:
The air extraction system is extracted from the door assembly and relocated to the rear wall of the washing chamber. This separation simplifies the door construction by removing the fan, ductwork, and associated components from the door structure, while maintaining effective air extraction functionality through the rear wall outlet configuration.
Solution Approach 2:
The air extraction outlet is positioned on the rear wall at a height above the maximum water level, utilizing the vertical dimension to ensure effective air extraction without interfering with the door mechanism. This spatial repositioning in the vertical dimension resolves the conflict between extraction efficiency and door construction simplicity.
2Productivity
If a radial fan with centrifugal impeller is used for air extraction, then damp air can be effectively removed from the tub, but the system becomes more complex and expensive to produce
Solution Approach 1:
The system utilizes the natural buoyancy and thermal rise of hot, moist air generated during the washing cycle. The air extraction outlet positioned above the maximum water level allows hot air to rise naturally and be extracted without requiring complex mechanical fans, thereby maintaining high air extraction effectiveness while simplifying the system and reducing production costs.
Solution Approach 2:
The mechanical fan system is replaced with a passive air extraction system that relies on thermal convection and buoyancy forces. The duct configuration and outlet positioning work together with natural air flow patterns to achieve effective moisture removal without mechanical assistance, reducing system complexity and manufacturing cost.
3Productivity
If the discharge duct has a tapered shape with decreasing height and increasing width, then airflow efficiency is improved, but manufacturing precision requirements increase
Solution Approach 1:
The tapered discharge duct is divided into multiple linear sections with discrete angle changes rather than a continuous curve. This segmentation into manageable angular zones simplifies the manufacturing process while maintaining the overall tapered geometry that promotes efficient airflow from the washing chamber to the external environment.
Solution Approach 2:
The duct geometry transitions from a complex continuous taper to a series of discrete angular sections with standardized dimensions. This parameter discretization maintains the functional benefits of the tapered shape for airflow efficiency while making the duct easier to manufacture using standard fabrication techniques and tolerances.
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 enhances air extraction efficiency, prevents condensation, and allows for a more compact and cost-effective design, enabling efficient drying with reduced encumbrance and increased flexibility in machine sizing.
Implementation Method 1
a system for extraction of damp air or steam from the tub (3), which comprises a radial fan (7) and a discharge duct (8)
Implementation Method 2
the discharge duct (8) comprises a hollow body (9) with a generally flattened shape, having an inlet portion (10) and an outlet portion (11)... an intermediate portion (12) with a height (H) that decreases, preferably in a substantially progressive way, towards the outlet portion (11)
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A dishwashing machine has a load-bearing structure that comprises a base supporting a washtub (3), there being articulated to the load-bearing structure a front door (4) of the washtub (3), the machine (1) moreover having a system for extraction of damp air from the tub (3), which comprises a fan (7) and a discharge duct (8) having a hollow body (9) with a width dimension and a height dimension. The fan (7) is a radial fan having a fan housing (7a), housed in which is a centrifugal impeller (7b), and the discharge duct (8) has an inlet portion (10) and an outlet portion (11). The intake mouth (7c) of the fan (7) is in fluid communication with an outlet opening (15) of the tub (3), the inlet portion (10) of the discharge duct (8) is in fluid communication with the delivery (7d) of the fan (7) and the outlet portion (11) of the discharge duct (8) is at the front of the machine (1). The discharge duct (8) has a portion (12) intermediate with respect to the inlet and outlet portions (10, 11) having a height (H) that decreases towards the outlet portion (11) and a width (W) that increases towards the outlet portion (11). At least the outlet portion (11) and the intermediate portion (12) of the discharge duct (8) extend over an upper wall (3a) of the tub (3), with the outlet portion (11) above an upper edge of the door (4). The outlet opening (15) is formed in one of the upper wall (3a) and a stationary side wall (3 c) of the tub (3), with the fan housing (7a) that is mounted on the aforesaid wall with the respective intake mouth (7c) that is at the outlet opening (15) and is substantially coaxial thereto. The damp air is drawn in from the outlet opening (15) substantially in the direction of the axis (A) of the impeller (7b) and forced in a radial direction into the discharge duct (8), and then expelled from the outlet portion (11) at the front of the machine (1) above the upper edge of the door (4).