Automatic door for dishwasher with multi-position sensing
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Solution Overview
Problem
Residential dishwashers require significant user effort to properly compress the door gasket for sealing during washing and venting during drying, and existing solutions are cumbersome or complex.
Innovation Solution
A mechanism using a DC motor and rack-and-pinion system with multipoint position sensing allows for automatic door opening and closing, reducing user effort and enabling 'soft close' functionality, with encoder tracks and sensors for precise position control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a vigorous pressing or lever-action latch is used to compress the door gasket, then the sealing force is sufficient, but the operation becomes cumbersome and requires adjustment over time
Solution Approach 1:
The door assembly performs self-service by automatically compressing the gasket through the weight and movement of the door itself, eliminating the need for external latches or vigorous user pressing. The door's own mass and controlled descent provide the necessary sealing force.
Solution Approach 2:
The mechanical latch system is replaced with an electric motor-driven plunger mechanism that uses controlled mechanical advantage through gears and a cam system to compress the gasket automatically, converting manual lever action into automated motor-driven compression.
2Productivity
If the door is opened for venting during drying, then drying efficiency improves, but noise transmission from the washing chamber increases
Solution Approach 1:
The door opening is segmented into multiple positions: fully closed for washing, partially open at a 45-degree angle for venting during drying, and fully open for loading. This segmentation allows the door to provide venting functionality while maintaining noise reduction during the drying cycle.
Solution Approach 2:
The door position is made dynamic and adjustable during operation, allowing it to transition between fully closed, partially open (45-degree), and fully open positions based on the washing cycle stage, enabling optimized noise control and venting performance.
3Device complexity
If a simple latch mechanism is used, then the device complexity is reduced, but the positioning precision and soft close control are insufficient
Solution Approach 1:
Mechanical position sensing mechanisms are replaced with electronic sensors including optical encoders and magnetic sensors that provide precise digital feedback on door position, enabling accurate control of the plunger movement and soft close functionality without complex mechanical linkages.
Solution Approach 2:
The system implements feedback control using optical encoders and magnetic sensors that continuously monitor door and plunger positions, allowing the control system to adjust motor output for precise positioning and controlled door closure, enabling soft close without excessive mechanical complexity.
4Speed
If the door is forced closed quickly, then the sealing action is rapid, but damage to entrapped cutlery or soft objects may occur
Solution Approach 1:
The door closing action is divided into periodic phases: initial rapid closure to achieve sealing, followed by a deceleration phase using the cam mechanism and spring damping, and finally a controlled soft close phase. This periodic speed variation enables rapid sealing while preventing damage to entrapped objects.
Solution Approach 2:
The system implements beforehand cushioning through the cam mechanism and spring-damper system that are pre-configured to engage before the door fully closes, providing progressive resistance and cushioning force to prevent sudden impact damage to cutlery or soft objects trapped in the door gap.
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 simplifies door operation, reduces user effort in sealing and venting, and provides improved drying efficiency while preventing damage to cutlery through precise control and position sensing.
Implementation Method 1
A DC motor communicates through at least one pinion gear with the gear rack to move the plunger along the axis in a first and second direction with different polarities of electrical current applied to the DC motor
Implementation Method 2
An encoder provides a signal distinguishing a position of the electric actuator among at least three different positions
Data Source
AI summary
A dishwasher (10) provides a motorized latch element extending to open the dishwasher door (18) for venting according to sense positions. A robust rack and pinion mechanism driven by a DC motor (50) provides flexible positioning of the door for different applications while ensuring sufficient force to compress the dishwasher gasket for sealing.