Electric PTO Transmission Shifting for Low-Speed Reverse Drive
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Solution Overview
Problem
Existing electric power take-off systems in vehicles face limitations in providing power at low speeds and in reverse drive modes, requiring higher motor speeds and specific gear and clutch arrangements to accommodate these conditions, which can reduce efficiency and increase complexity.
Innovation Solution
A dual-motor electrical transmission system with two optional gear sets and clutches that allows power take-off to be coupled to either of two electric motors, enabling power delivery in both forward and reverse drive modes at low speeds, and allowing independent operation of the motors to maximize efficiency and maintain output torque during gear shifting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the power take-off is coupled to a single electric motor in first gear at low speed, then the motor speed is limited, but the power take-off necessitates a minimum speed that is higher than the motor speed
Solution Approach 1:
The system dynamically switches between two different gear sets (first and second gear sets) depending on operating conditions. When in first gear at low speed, the system engages the second gear set which provides a different gear ratio, allowing the power take-off to receive sufficient rotational speed even when the motor operates at low speed. This dynamic reconfiguration of the transmission path resolves the speed mismatch between motor output and PTO requirements.
2Device complexity
If the power take-off requires forward drive only, then the gear and clutch arrangements are simplified, but the system cannot operate in reverse drive mode
Solution Approach 1:
The transmission system is designed with two gear sets that enable the power take-off to be coupled to the motor through different transmission paths. One gear set is optimized for forward drive while the other enables reverse drive operation. This multi-functionality allows the same PTO system to operate effectively in both forward and reverse drive modes without requiring separate systems, thereby achieving versatility while maintaining reasonable complexity.
3Adaptability or versatility
If additional gear sets and clutches are added to enable low speed and reverse operation, then the drive capability is improved, but the transmission complexity increases
Solution Approach 1:
The patent integrates two gear sets into a single transmission housing, sharing common components such as the motor coupling, output shaft, and control mechanisms. The first and second gear sets are arranged to share space and functional elements, allowing the system to achieve enhanced drive capability (forward and reverse operation at various speeds) while minimizing the increase in overall complexity through compact integration and component sharing.
Data Source
AI summary
A method and system for operating a transmission that includes a power take off is described. The transmission selectively delivers mechanical power to the power take off from one of two electric traction motors via selective engagement of either a first or a second power take off clutch based on drive mode. The transmission also allows for powershifting between a first and second operating gear.