Counter-Rotating Output Shafts in Vehicle Drive Assembly
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Solution Overview
Problem
Existing drive arrangements for motor vehicles, particularly commercial vehicles, face challenges with reaction torques that cause stress and overload in the drivetrain, especially in low gear ratios, which are not effectively managed by current designs.
Innovation Solution
The differential in the drive unit drives two counter-rotating output shafts, which are connected to cardan shafts that drive the wheels, allowing the reaction moments to cancel each other out, reducing the complexity and load on the unit bearings and enabling a more efficient distribution of torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the differential drives a single output shaft in conventional drive arrangements, then the drive torque is transmitted to the wheels, but high reaction torques cause stress and overload in the drivetrain components
Solution Approach 1:
The single output shaft is segmented into two counter-rotating output shafts, each driving a separate cardan shaft. This segmentation divides the reaction torque into two opposing directions, causing the moments to cancel each other out and significantly reducing the stress on drivetrain components while maintaining full power transmission capability
Solution Approach 2:
The second output shaft rotates in the opposite direction to the first, creating counterbalancing reaction moments that neutralize each other. This anti-weight principle eliminates the net reaction torque that would otherwise overload the drivetrain components, allowing high power transmission without corresponding stress increases
2Power
If conventional drive arrangements are used with single output shafts, then the drivetrain can transmit power, but the unit bearings and transmission elements must be designed to handle high reaction moments
Solution Approach 1:
The power transmission path is segmented into two separate counter-rotating shafts, each handling half of the reaction moment. This allows the unit bearings to be designed for lower individual loads while collectively supporting the same total power, reducing bearing complexity and design requirements
3Power
If high drive torques occur in low gear ratios, then the vehicle can achieve high starting torque, but the reaction torques cause tension and overload in the drive train
Solution Approach 1:
The counter-rotating output shafts create opposing reaction moments that cancel each other out, even when high drive torques are generated in low gear ratios. This allows the vehicle to maintain high starting torque capability while the reaction forces neutralize each other, preventing drive train overload
Data Source
Figure 1~2
Figure 3~4
AI summary
The assembly has an internal combustion engine (2), a downstream arranged speed change gear (3) and a differential gear (4) e.g. intermediate axle differential gear, bevel differential gear and planetary drive, assembled in a drive unit (1), where the gear drives a driven axis of a motor vehicle. The gear has beveled wheels (9) and intermediate shafts (12) acting on two driven shafts (10, 14) that are rotatably supported in the drive unit. The driven shafts are driven opposite to each other and connected with hinge shafts (11, 15) that drive rear wheels (21) of the vehicle.