Planetary Transmission Sun Shaft Integration for Lower Assembly Cost
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Solution Overview
Problem
The existing production methods for planetary gear transmissions with three coaxially coupled gearsets are costly due to separate manufacturing and assembly of sun gears, which increases production time and expenses.
Innovation Solution
Integrating the second and third sun gears with the driveshaft, allowing for a single-step milling process and shared tooling, reducing production costs by eliminating the need for separate gearwheel assembly and enabling a conjoint sun shaft for torque transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the second and third sun gears are manufactured as separate gearwheels and joined to the driveshaft, then the assembly allows for modular construction and replacement, but the production cost and manufacturing time increase due to multiple separate manufacturing steps and assembly operations
Solution Approach 1:
The patent merges the second and third sun gears directly into the driveshaft by integrating their tooth profiles during the driveshaft manufacturing process. This eliminates the need for separate gearwheel production and assembly operations, reducing both production cost and manufacturing steps while maintaining the functional requirements of the transmission system
2Productivity
If the second and third sun gears are manufactured as separate gearwheels and joined to the driveshaft, then the gears can be produced independently, but the production time and manufacturing expenses increase due to multiple separate manufacturing and assembly steps
Solution Approach 1:
The patent combines the manufacturing of the second and third sun gears with the driveshaft production into a single integrated process. The tooth profiles are cut directly into the driveshaft during its manufacturing, eliminating sequential production steps and reducing total production time while maintaining independent gear functionality
Solution Approach 2:
The driveshaft is designed to serve multiple functions simultaneously: it acts as the rotational shaft and as the carrier for both the second and third sun gears. This multi-functionality eliminates the need for separate gearwheel components and reduces the number of manufacturing operations required
3Adaptability or versatility
If the outer diameters of the two sun gears are made different, then the gears can be optimized for different gear ratios, but the production cost increases due to requiring different tools and manufacturing steps
Solution Approach 1:
The patent applies different tooth profile characteristics at different locations along the driveshaft while maintaining a uniform outer diameter. This allows optimization for different gear ratios through local variations in tooth geometry rather than overall diameter differences, enabling gear ratio flexibility while using the same manufacturing tooling
Data Source
AI summary
A motor vehicle transmission having a planetary gear system with three coaxially arranged gearsets (RS1, RS2, RS3) coupled to one another. The first gearset (RS1) includes a first sun gear (SR1), a first planet carrier (ST1) and a first ring gear (HR1). The second gearset (RS2) includes a second sun gear (SR2), a second planet carrier (ST2) and a second ring gear (HR2), and the third gearset (RS3) includes a third sun gear (SR3), a third planet carrier (ST3) and a third ring gear (HR3). The second and third gearsets (RS2, RS3) have the same stationary gear ratio and the second and third sun gears (SR2, SR3) are arranged in a rotationally fixed manner on a common driveshaft (AW). The second and third sun gears (SR2, SR3) are made integrally with the driveshaft (AW).