Dual-Motor Dolly Propulsion With Split Gear Ratios Across Speed Range
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Solution Overview
Problem
Existing self-powered dolly vehicles face challenges in generating sufficient torque across a wide range of vehicle speeds, from standstill to highway cruising, which affects their performance and efficiency in cargo transport.
Innovation Solution
A propulsion arrangement featuring two electric machines with different gear ratios, one fixed and one configurable, connected via a gearbox and open differential, allowing for adaptable torque generation and regenerative braking, controlled by a processing unit that adjusts gear ratios based on vehicle speed to optimize performance across various driving scenarios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single electric machine with fixed gear ratio is used, then the device complexity is reduced, but the adaptability to different vehicle speeds and torque requirements deteriorates
Solution Approach 1:
The propulsion arrangement is segmented into two separate electric machines (first and second electric machines), each with its own gearbox and gear ratio configuration. This segmentation allows each machine to specialize in different speed ranges, with the first machine handling low-speed high-torque scenarios and the second machine handling high-speed cruising, thereby improving overall adaptability without requiring a single complex variable-ratio system
Solution Approach 2:
The system dynamically switches between different electric machines and gear ratios based on vehicle speed requirements. The control unit monitors vehicle speed and selectively engages the first electric machine with first gear ratio for low-speed operation, or the second electric machine with second gear ratio for high-speed operation, providing dynamic adaptability to varying driving conditions
2Adaptability or versatility
If two electric machines with different gear ratios are used, then the adaptability to different vehicle speeds is improved, but the device complexity increases
Solution Approach 1:
Both electric machines are connected to the same driven axle through respective gearboxes, creating a universal propulsion system that can handle both starting from standstill and highway cruising. The control unit selectively activates the appropriate machine based on speed requirements, allowing the system to perform multiple functions (low-speed torque delivery and high-speed cruising) without requiring separate propulsion systems for each function
Solution Approach 2:
The system changes the gear ratio parameter by selecting between the first gear ratio (higher ratio for torque multiplication) and the second gear ratio (lower ratio for high-speed efficiency). This parameter change allows the propulsion arrangement to optimize performance across different speed ranges, with the control unit automatically selecting the appropriate gear ratio based on real-time speed measurements
3Productivity
If a configurable gear ratio system is implemented, then the productivity across different driving scenarios is improved, but the ease of operation deteriorates
Solution Approach 1:
The control unit automatically monitors vehicle speed and selects the appropriate electric machine and gear ratio configuration without requiring manual intervention. The system self-adjusts by engaging the first electric machine for low-speed scenarios and the second electric machine for high-speed scenarios, thereby improving productivity across different driving scenarios while maintaining ease of operation through automated control
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 configuration enhances the dolly vehicle's startability and cruising capabilities, providing flexible torque delivery and energy management, thereby improving overall vehicle performance and fuel efficiency across a wide range of speeds.
Implementation Method 1
a first electric machine, a second electric machine, a gearbox, and an open differential for driving first and second wheels of a driven axle
Implementation Method 2
connected to the open differential via the gearbox at respective gear ratios
Implementation Method 3
open differential for driving first and second wheels of a driven axle
Data Source
Figure 1~2
Figure 3A~3B
Figure 4~5B
AI summary
A propulsion arrangement (400) for a self-powered dolly vehicle unit, the propulsion arrangement comprising a first electric machine (410), a second electric machine (420), a gearbox (430), and an open differential (450) for driving first and second wheels (310l, 310r) of a driven axle (470), wherein the first (410) and second (420) electric machines are arranged in parallel and connected to the open differential (430) via the gearbox (430) at respective gear ratios (g1, g2, g3).