Dishwasher Diverter Valve Drive With Rotor-Level No-Back Mechanism
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Solution Overview
Problem
Dishwasher AC synchronous motors face inefficiencies and excessive force on components due to asymmetry in stator parts and the need for strong no-back features to prevent unwanted rotor direction changes.
Innovation Solution
A dishwasher diverter valve drive with a no-back feature integrated near the rotor, featuring a motor cup with apertures for the no-back component, allowing it to oscillate in the desired direction and stop in the undesired direction, eliminating the need for excessive force resistance and asymmetrical stator design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the no-back feature is positioned in the gear train to prevent unwanted rotor direction changes, then the motor can operate in a single rotational direction, but the no-back feature must withstand excessive force applied farther down the gear train
Solution Approach 1:
The no-back feature is extracted from the gear train and repositioned to engage directly with the rotor assembly. This removes the mechanical disadvantage of force multiplication through the gear train, allowing the no-back feature to withstand the required forces without excessive stress on gear components.
2Strength
If the no-back feature is made stronger to withstand excessive force, then it can prevent unwanted rotor direction changes effectively, but other components in the gear train may be weakened by comparison
Solution Approach 1:
By extracting the no-back feature from the gear train and positioning it at the rotor assembly, the system eliminates the need for the no-back feature to be excessively strong. The force is applied directly at the source rather than being amplified through gear multiplication, creating a more balanced strength distribution across all components.
3Force
If the no-back feature is located at or near the rotor, then it reduces force on other components, but it requires positioning in an area less affected by force which may limit design options
Solution Approach 1:
The motor cup is designed with multiple apertures that can accommodate the no-back feature at various angular positions. This universal positioning capability allows the no-back feature to be located in areas less affected by force while maintaining design flexibility and adaptability for different operational requirements.
4Reliability
If the stator is designed with asymmetry to enable single rotational direction operation, then the motor achieves desired directional control, but the design becomes more complex compared to symmetrical designs
Solution Approach 1:
The patent employs asymmetry in the stator design with unequal pole pitches to inherently bias the motor toward single-direction rotation. This asymmetric configuration, combined with the no-back feature, provides reliable directional control while maintaining a relatively simple overall design by using the motor's electromagnetic characteristics rather than complex mechanical asymmetries.
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 reduces component stress and improves motor efficiency by allowing the no-back feature to oscillate and stop effectively without additional modifications, enhancing the motor's operational reliability and reducing force on components.
Implementation Method 1
An AC synchronous motor is an electric motor driven by an alternating current (AC). Such a motor is synchronous when a rotation period of the motor is equal to a number of AC cycles.
Implementation Method 2
A no-back component is configured to oscillate when the synchronous motor is rotating in a desired direction, and the no-back component is configured to move to a stopping position when the synchronous motor is rotating in an undesired direction.
Data Source
AI summary
An AC motor, and method of operation, including a synchronous motor with a magnetic rotor, and a stator positioned at a fixed distance from the magnetic rotor. A no-back mechanism is configured to oscillate when the synchronous motor is rotating in a desired direction, and the no-back component is configured to move to a stopping position when the synchronous motor is rotating in an undesired direction.