Lower Spray Arm Position Control for Zonal Dishwasher Washing
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Solution Overview
Problem
Traditional dishwasher spray arms rely on hydraulic drive, which is dependent on pump flow rate and pressure, limiting control over rotational speed and direction, and often stall during cycles, impacting cleaning performance.
Innovation Solution
A motor-driven lower spray assembly with a controller that adjusts recirculation pump motor speed for optimal water flow and pressure, allowing independent control of rotation speed and direction, and includes a sensor system to accurately determine and control the spray arm's position relative to the filter for focused cleaning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If hydraulic drive is used for spray arms, then the system is simple and relies on pump flow, but rotational speed and direction control are limited and stalling occurs
Solution Approach 1:
The patent replaces the hydraulic drive system with an electric motor-driven system. The motor provides direct mechanical drive to the spray arm, enabling precise control of rotational speed and direction through electrical signals. This substitution eliminates the dependency on pump flow rate and pressure, preventing stalling issues that occur in hydraulic systems when flow conditions vary.
2Adaptability or versatility
If motor-driven spray assembly is used, then independent control of rotation is achieved, but device complexity increases
Solution Approach 1:
The electric motor serves multiple functions: it drives the spray arm rotation, allows variable speed control, enables bidirectional rotation, and can be precisely positioned. By consolidating these multiple functions into a single motor-driven system with electronic control, the patent achieves high adaptability without proportionally increasing complexity, as the motor and controller replace what would otherwise require multiple separate mechanical components.
3Productivity
If spray arm rotates continuously, then wash coverage is maintained, but water is wasted and energy is consumed
Solution Approach 1:
The spray arm operates with periodic motion patterns rather than continuous rotation. The controller programmed the motor to rotate the spray arm through specific arcs and pause at predetermined positions to concentrate spraying on heavily soiled areas. This periodic action with variable speed and position allows maintaining effective wash coverage while reducing overall water consumption and energy use compared to continuous rotation.
4Manufacturing precision
If spray arm lingers at filter location, then focused cleaning of filter is achieved, but rotation control complexity increases
Solution Approach 1:
The system uses feedback control to achieve precise positioning of the spray arm at the filter location. Sensors detect the position of the spray arm and provide feedback to the controller, which adjusts the motor operation to achieve and maintain the desired position. This feedback mechanism enables accurate positioning and lingering at specific locations without requiring overly complex mechanical positioning mechanisms.
Data Source
AI summary
A dishwasher for treating dishes according to at least one cycle of operation and methods for operating a dishwasher. The dishwasher may have a tub at least partially defining a treating chamber, a rotatable sprayer, a drive system operably coupled to the rotatable sprayer to effect movement of the rotatable sprayer, and a liquid recirculation system for recirculating sprayed liquid. The dishwasher may have a sump including a sensor enclosure, a first sensor element located within the sensor enclosure and configured to sense at least a portion of the rotatable sprayer, and a controller configured to receive output from the first sensor element and control the drive system and the liquid recirculation system to rotate the rotatable sprayer while selectively supplying liquid to the rotatable sprayer.