Dishwasher Spray Arm Rotation Detection Using Mechanical Switch
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Solution Overview
Problem
Current dishwasher spray arm arrangements face challenges in detecting blockages and maintaining precise rotation, leading to inefficient water and energy use, as well as inadequate cleaning of heavily soiled items, due to limitations in spray pressure and imprecise monitoring methods.
Innovation Solution
A dishwasher with a spray arm arrangement that includes a mechanical switch and an activating device with multiple activating structures to cyclically activate the switch, allowing for controlled detection of the spray arm's angular position and rotational speed, enabling adaptive cleaning intensity based on the location of items within the washing chamber.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a deflecting wall is used to detect spray arm rotation, then rotation detection is enabled, but the detection precision deteriorates when spray nozzles are clogged or multiple nozzles hit the wall simultaneously
Solution Approach 1:
The patent replaces the mechanical deflecting wall system with an optical detection system. A light source and light receiver are positioned such that the rotating spray arm periodically interrupts the light beam, creating detection signals. This optical system eliminates the problems of the mechanical deflecting wall, including sensitivity to spray pressure variations, clogging issues, and imprecise detection when multiple nozzles activate simultaneously. The optical beam provides consistent, reliable detection regardless of spray nozzle condition.
2Object-affected harmful factors
If spray pressure is limited to protect delicate items, then glass and delicate items are protected, but cleaning effectiveness on heavily soiled items deteriorates
Solution Approach 1:
The patent implements dynamic spray pressure control by coupling the spray nozzles with a controllable pump system. The pump can vary its output pressure in real-time based on detected conditions. When delicate items are detected in the washing chamber, the system reduces spray pressure to protect them. When only robust items like pots and pans are present, the system increases spray pressure to ensure thorough cleaning. This dynamic adjustment resolves the contradiction between protecting delicate items and effectively cleaning heavily soiled items.
3Reliability
If a rotation detection sensor is added to monitor spray arm rotation, then blocked spray arm detection is enabled, but device complexity increases
Solution Approach 1:
The patent makes the optical detection system multi-functional. The same light source and light receiver assembly that detects spray arm rotation is also used to detect the presence and type of items in the washing chamber. By positioning the optical components to detect both rotation signals and item characteristics, the system eliminates the need for separate sensors. This universal approach enables blocked spray arm detection, item classification, and spray pressure control using a single integrated optical system, thereby reducing overall device complexity.
Data Source
AI summary
A dishwasher may include a spray arm arrangement and a washing chamber. The spray arm arrangement may include a spray arm arranged to rotate around a first axis of rotation within said washing chamber. The spray arm may be provided with one or more spray nozzles arranged to spray washing liquid into said washing chamber. The dishwasher may also include a mechanical switch for detecting an angular position of said spray arm. The spray arm arrangement may further include an activating device arranged to rotate with said spray arm, which activating device may include at least one activating structure arranged to cyclically activate said mechanical switch during rotation of said spray arm.