Dishwasher Reversing Drive Control Without Position Feedback
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Solution Overview
Problem
Existing dishwasher technologies require complex and costly mechanisms to control the reversing device, which complicates the operation and increases the number of components, leading to reduced positioning accuracy and higher manufacturing costs.
Innovation Solution
A dishwasher design featuring a reversing device with an electric drive that uses a motor and control device to set predefined positions without the need for feedback mechanisms, utilizing zero crossings of counter-EMF to determine rotation angles and mechanical blocking means to ensure accurate positioning, thereby simplifying the operation and reducing component count.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If feedback mechanisms (microswitches) are used to control the reversing device position, then positioning accuracy can be maintained, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent removes the feedback mechanism (microswitch) from the system entirely. Instead of using a microswitch to detect and feedback the reversing device position, the system uses open-loop control where the control device directly commands the drive to rotate to predetermined angles based on stored position data, eliminating the need for physical feedback components while maintaining positioning accuracy through precise angle control
Solution Approach 2:
The patent implements internal feedback through the control device that stores predetermined angle data corresponding to different spray arm positions. The control device uses this stored information to command the drive to rotate the reversing device to the correct angle without needing external feedback sensors, creating a software-based feedback mechanism that replaces hardware microswitches
2Manufacturing precision
If microswitches and feedback devices are installed to control reversing device positions, then positioning can be achieved, but manufacturing cost increases
Solution Approach 1:
The patent replaces expensive, complex feedback hardware (microswitches, sensors, feedback circuits) with a simpler, more cost-effective solution using stored angle data and open-loop control. The system achieves the same positioning function using inexpensive components already present in the drive mechanism, eliminating the need for additional costly feedback devices
Solution Approach 2:
By removing the microswitch and feedback mechanism from the system, the patent eliminates associated manufacturing costs including component procurement, assembly, calibration, and maintenance. The positioning function is achieved through software control using predetermined angle data, significantly reducing manufacturing complexity and cost
3Ease of operation
If complex mechanisms with multiple components are used to control the reversing device, then positioning can be achieved, but operational complexity increases
Solution Approach 1:
The patent combines the control functions of position detection, position calculation, and drive activation into a single integrated control device. Instead of separate microswitches, position sensors, calculation units, and drive controllers, the system uses one control device that stores position data and executes the complete control sequence, simplifying operation and reducing mechanical complexity
Solution Approach 2:
The control device autonomously determines the correct reversing device position based on stored predetermined angle data corresponding to spray arm positions. The system self-regulates without requiring external feedback or manual intervention, automatically commanding the drive to rotate to the correct angle based on the current washing program requirements
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
This solution allows for cost-effective and accurate positioning of the reversing device, eliminating the need for additional feedback components and enhancing the dishwasher's operational efficiency and manufacturing cost-effectiveness.
Implementation Method 1
by determining zero crossings of a counter-EMF of the motor while it is rotating through the specified angle
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The invention relates to a dishwasher (1) and a method for operating said dishwasher (1). The dishwasher (1) comprises a washing receptacle (2), at least two spraying arms (5, 6) located inside the washing receptacle (2), a reversing device (14, 14a), an electric drive (19) that is designed to move the reversing device (14, 14a) into different positions by means of the motor (25) of the electric drive (19), a control device (18) for controlling the electric drive (19), and a circulation pump (7) which conveys liquid to one of the two and/or both spraying devices (5, 6) according to the set position of the reversing device (14, 14a). The control device (18) is designed to control the electric drive (19) in such a way that the electric motor (25) of the electric drive (19) first moves the reversing device (14, 14a) into a predefined starting position, whereupon the motor (25) rotates by a predefined angle and thereby moves the reversing device (14, 14a) into one of the positions without providing any feedback on the current position of the reversing device (14, 14a).