Planetary helical gear train for a transmission assembly of a washing machine appliance
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Solution Overview
Problem
Conventional washing machine transmissions using spur gears are noisy, particularly when their rotation direction is reversed, which is undesirable for consumer preferences seeking quieter operation.
Innovation Solution
A vertical axis washing machine employs a planetary helical gear transmission system with a sun gear, ring gear, and planetary gears, along with ball bearings to manage axial thrust loads and prevent gear shuttling, reducing noise and improving operational quietness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If spur gears are used in the gear train, then the transmission can be simpler and less expensive, but the washing machine generates noisy operation and clicking noise when rotation direction is reversed
Solution Approach 1:
The patent changes the gear tooth geometry from straight spur gears to helical gears with angled teeth. This parameter change in the gear design allows for gradual engagement of teeth during rotation, which eliminates the sudden impact and clicking noises characteristic of spur gears, especially during direction reversals. The helical configuration distributes contact across multiple teeth simultaneously, reducing noise and vibration while maintaining the same basic gear train structure.
2Object-generated harmful factors
If helical gears are used instead of spur gears, then noise is reduced, but axial thrust loads are generated that require additional bearing support
Solution Approach 1:
The patent introduces ball bearings as intermediary components between the helical gears and the gear train housing. These bearings serve as mediators that support and manage the axial thrust loads generated by the helical gear engagement. By placing bearings at strategic locations, the patent enables the use of quiet helical gears while providing the necessary mechanical support to handle the additional axial forces, effectively decoupling the noise reduction benefit from the load management requirement.
3Volume of moving object
If a planetary gear system is implemented, then gear reduction is achieved with a compact design, but the structure becomes more complex with multiple moving parts
Solution Approach 1:
The patent merges multiple gear functions into a single planetary gear system. The planetary arrangement combines the sun gear, planet gears, and ring gear into one integrated unit that provides gear reduction while occupying minimal space. By combining the functions of multiple gear stages into this single compact planetary assembly, the patent achieves high gear reduction ratios without proportionally increasing the overall transmission size, as all components work simultaneously rather than in sequence.
Solution Approach 2:
The planetary gear system employs a nested configuration where planet gears are positioned around and engage with both the central sun gear and the outer ring gear. This nesting arrangement allows multiple gear elements to occupy the same radial space, creating a compact transmission unit. The sun gear is nested within the planet gears, which are in turn nested within the ring gear, maximizing the use of available space and achieving compact design without excessive structural complexity.
Data Source
AI summary
A vertical axis washing machine appliance having a transmission assembly with a planetary helical gear train is provided. The transmission assembly transmits mechanical power from a torque source to an agitation element so that oscillatory motion may be imparted to laundry articles within a wash basket of the washing machine appliance, e.g., during a wash cycle. The transmission assembly includes features that manage axial thrust loads created by helical gears of the gear train. The transmission assembly also includes features that prevent shuttling of the gears and other components of the transmission assembly.