Planetary Wheel Assembly Bore for Fatigue-Resistant Gear Carriers
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Solution Overview
Problem
Existing planetary gears face challenges in achieving high fatigue strength and easy assembly while being cost-effective, particularly due to the sensitivity of plastic components to external influences during the injection molding process and the need for efficient torque transmission in small spaces.
Innovation Solution
A planetary wheel design featuring a wheel body with extended bearing sections and a coaxial bore for assembly, combined with a planetary carrier having elastic catching projections for quick assembly and stress distribution, along with ribs and stop projections for enhanced strength and wear resistance, allows for stable manufacturing and assembly processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If planetary gears are made of plastic using injection molding for mass production, then manufacturing cost and productivity are improved, but manufacturing precision and reliability deteriorate due to sensitivity to external influences during assembly
Solution Approach 1:
The patent introduces an assembly tool with a pin that interacts with a specifically designed assembly bore in the planetary wheel. This intermediary tool enables precise alignment and insertion of the planetary wheel into the carrier without direct handling of the sensitive bearing surfaces, thereby maintaining manufacturing precision while enabling mass production through standardized assembly processes
Solution Approach 2:
The patent separates the assembly interface into two distinct parts: the assembly bore in the planetary wheel and the corresponding assembly feature in the carrier. By extracting the assembly function from the bearing surfaces themselves, the design allows mass production with standardized tools while protecting the critical bearing surfaces from damage during assembly
2Reliability
If planetary gears are designed for high fatigue strength to withstand heavy loads, then reliability is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The planetary wheel is segmented into distinct functional zones: bearing sections for rotational support, tooth sections for torque transmission, and an assembly bore for manufacturing. This segmentation allows each zone to be optimized for its specific function while maintaining overall structural integrity and fatigue strength under heavy loads
Solution Approach 2:
The patent applies different structural characteristics to different parts of the planetary wheel: the bearing sections have smooth surfaces and specific geometries for rotational compatibility, the tooth sections have hardened surfaces for wear resistance, and the overall structure incorporates reinforcement features for fatigue strength. This local differentiation achieves high reliability without unnecessary overall complexity
3Ease of operation
If assembly processes are simplified for quick assembly, then ease of operation is improved, but manufacturing precision may deteriorate due to rough handling
Solution Approach 1:
The planetary wheel bore is pre-configured with specific geometric features that guide the assembly tool pin during insertion. This preliminary preparation of the assembly interface ensures that quick assembly can be performed without compromising alignment accuracy, as the geometry itself enforces proper positioning during the rapid assembly process
Data Source
AI summary
The present invention relates to a planetary wheel (10) for a planetary gear (14) with a planetary wheel bore (28) which runs coaxially or parallel to the planetary wheel axis of rotation (APR) and which at least partially runs through the planetary wheel axis (22). The invention also relates to a planetary carrier (44) for such a planetary wheel (10), comprising a carrier body (46) with a first disk-shaped body (48) which has at least one first bearing recess (60), which has at least one circumferentially extending first catching projection (64), and with a second disk-shaped body (50) having at least one second bearing recess (62), which has at least one circumferentially extending second catching projection (66).