Electric Drive Transmission with Variable Reduction for Highway Torque
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Solution Overview
Problem
Existing electrically-driven vehicles consume more energy on highways than in cities due to the need for high rotational speeds of the electric machine to maintain torque, reducing the mileage range.
Innovation Solution
An electrically-driven vehicle with an epicyclic train architecture and an irreversible reduction mechanism, comprising a regulating motor and worm and wheel system, adjusts torque transmission to the drive wheels based on accelerator pedal input, using an electronic control unit to modulate rotational speed and torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a constant power reducer with high reduction ratio is used to provide sufficient torque to the drive wheels, then the torque transmission capability is improved, but the electric machine must operate at high rotational speed which increases energy consumption
Solution Approach 1:
The patent applies a variable reduction ratio mechanism that dynamically adjusts the reduction ratio based on operating conditions. The mechanism includes a movable planet carrier that can change its position relative to the sun gears, enabling the reduction ratio to vary continuously. This allows the system to use higher reduction ratios when high torque is needed (low speed) and lower reduction ratios when high speed is needed (high speed), resolving the contradiction between torque capability and energy consumption.
Solution Approach 2:
The invention changes the reduction ratio parameter dynamically rather than using a fixed value. By adjusting the position of the planet carrier and changing the engagement state of the clutch elements, the system modifies the transmission characteristics in real-time. This parameter change enables optimal matching between motor operating point and load requirements, reducing energy consumption while maintaining torque capability.
2Force
If the electric machine operates at high rotational speed to maintain torque on highways, then the torque delivery is maintained, but the mileage range is reduced
Solution Approach 1:
The variable reduction ratio mechanism enables the electric machine to operate at lower rotational speeds while delivering the same torque to the wheels. By increasing the reduction ratio when needed, the system allows the motor to run at more efficient operating points, extending the duration of action (mileage range) without sacrificing torque delivery capability.
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
Enhances torque delivery to the drive wheels while reducing energy consumption, particularly at high speeds, thereby increasing the vehicle's mileage range.
Implementation Method 1
the irreversible reduction mechanism being a worm and wheel system whose worm is coupled in rotation with an output shaft of the regulating motor and whose wheel is coupled in rotation with the planet carrier of one stage of said at least one stage of the main reducer
Implementation Method 2
the power transmission mechanism comprising a main reducer interposed between the power motor and the drive wheels, said main reducer having an epicyclic train architecture with at least one stage
Data Source
AI summary
The invention relates to a vehicle with electric drive (1), comprising driven wheels (3); a propulsion unit (10) including at least one electric power motor (11) and a power transmission mechanism (20) transmitting power between said power motor (11) and the driven wheels (3): and a regulator mechanism (30) comprising a regulating motor (31) and an irreversible reduction mechanism (33) interposed between the regulating motor (31) and the power transmission mechanism (20) and acting on the power transmission mechanism (20) in such a way as to allow the value of the mechanical torque transmitted by the power transmission mechanism (20) to the driven wheels (3) to be adjusted as a function of the rotational speed of the regulating motor (31). The invention also relates to a method for controlling such an electrically driven vehicle (1).