Drive Assembly Housing with Integrated Ring Gear
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Solution Overview
Problem
Existing drive assemblies for transmitting rotational power have high manufacturing costs due to the need for extensive and heavy housings, precise machining, and expensive manufacturing techniques, particularly when using a two-piece assembly with a cast or ductile iron housing and steel ring gear, or a one-piece gear steel housing that requires shaper cutting for gear teeth formation.
Innovation Solution
A drive assembly design featuring a separate housing with an integrally formed ring gear interface around its internal circumference, which is press fit or shrink fit to an attachment lip, allowing for more cost-effective manufacturing and the use of less expensive techniques like broaching for gear formation, reducing material and manufacturing expenses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a two-piece assembly with cast or ductile iron housing and steel ring gear is used, then the structural strength and reliability are improved, but the manufacturing cost and device complexity increase
Solution Approach 1:
The patent combines the housing and ring gear into a single integrated component where the ring gear is formed directly as part of the housing structure. This merging eliminates the need for separate casting and assembly operations, reducing manufacturing complexity and cost while maintaining the structural strength of both components through unified material selection and formation processes.
Solution Approach 2:
The housing structure is designed to serve multiple functions simultaneously: it provides the structural enclosure for the planetary gear set, forms the ring gear teeth for gear engagement, and creates the mounting interface for the output hub. This multi-functionality reduces the number of separate parts needed while maintaining reliability.
2Ease of manufacture
If a one-piece housing manufactured out of gear steel is used, then the manufacturing process is simplified, but the manufacturing cost increases due to shaper cutting requirements
Solution Approach 1:
The patent segments the housing formation process into two distinct phases: first, casting or forming the basic housing structure from cost-effective materials, and second, adding the ring gear teeth through more economical processes such as broaching or rolling rather than expensive shaper cutting. This segmentation allows each feature to be created by the most appropriate and cost-effective method.
Solution Approach 2:
The housing base structure is prepared in advance through casting or forming operations that create the overall shape and mounting features before the ring gear teeth are added. This preliminary action allows the use of low-cost forming methods for the main structure, with the expensive tooth-cutting operation applied only to the specific gear engagement surfaces that require precision.
3Manufacturing precision
If extensive housing and precise machining are used, then the manufacturing precision and reliability are improved, but the manufacturing cost increases
Solution Approach 1:
The patent applies high-precision machining operations only to the specific localized areas where ring gear teeth are formed and where precision is critical for gear engagement, while the remainder of the housing structure is produced through more economical casting or forming processes. This local quality approach ensures precision where needed without incurring the cost of precision machining throughout the entire housing.
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 design significantly reduces material and manufacturing costs while enabling efficient power transmission from a motor to an output hub, using a planetary gear set within the housing to provide speed reduction, and allows for the use of less expensive materials and manufacturing methods.
Implementation Method 1
Rotational power may be transmitted from the planetary gear set to the output interface via the gear teeth and the connection between the attachment surfaces
Implementation Method 2
A planetary gear set is coupled to the motor and is disposed within the housing in order to provide a speed reduction of various ratios to rotational power received from the motor
Data Source
AI summary
A drive assembly is disclosed, including a housing cylinder having a cap end and an attachment end including a first attachment surface, with gear teeth being disposed around an inner circumference forming at least one ring gear. The housing cylinder encloses a planetary gear set including at least one sun gear and at least one set of planet gears. An output interface includes an interface body having an annular attachment lip including a second attachment surface. The first attachment surface contacts, and is connected, as by welding, to the second attachment surface, whereby rotational power may be transmitted from the planetary gear set to the output interface via the gear teeth and the contact between the attachment surfaces.