Dual-Motor Planetary CVT for EV Torque and Energy Balance
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Solution Overview
Problem
Existing electric vehicles face challenges in maintaining high energy efficiency and driving performance, particularly on complex roads and steep inclines, due to the consumption of excessive electrical energy and the need for large, high-output motors, which increase weight and reduce efficiency.
Innovation Solution
A continuously variable transmission drive system using two motors and a planetary gear train, with a gear shifter that selectively controls the rotation of an idler gear, allowing for variable torque and speed adjustments based on road conditions, and includes a gear shifter to physically fix the idler gear when power to the second motor is cut off, reducing energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If high-output motors are used to achieve high torque for steep roads and high speeds, then driving performance is improved, but electrical energy consumption increases and vehicle weight increases
Solution Approach 1:
The patent divides the single motor system into two separate motors (first motor and second motor), each capable of operating independently or in combination. This segmentation allows the system to use only the necessary motor power for current driving conditions, avoiding the continuous high energy consumption of a single high-output motor. The first motor can handle moderate torque requirements while the second motor provides additional torque when needed for steep roads or high speeds.
Solution Approach 2:
The patent implements a dynamically adjustable transmission system using a planetary gear train with variable gear ratios. The gear shifter can continuously change the gear ratio to match driving conditions, allowing the motors to operate at optimal efficiency points. This dynamic adjustment enables the system to deliver high torque when needed while maintaining low energy consumption during normal driving conditions.
2Force
If high-output motors are used to achieve high torque, then driving performance is improved, but the size and weight of the motor and reducer increase
Solution Approach 1:
By splitting the power delivery function across two smaller motors rather than one large motor, the system achieves the same or greater torque capability while reducing individual motor sizes. The first motor and second motor can be more compact than a single high-output motor, and when not fully engaged, their combined weight is less than a continuously high-capacity motor would require.
Solution Approach 2:
The patent employs a planetary gear train where gears are nested within each other (sun gear, planetary gears, ring gear). This nested configuration allows for compact transmission of torque multiplication without requiring a large reducer housing, thus reducing the overall size and weight of the powertrain system while maintaining high torque output capability.
3Use of energy by moving object
If a planetary gear train with two motors is used to vary torque and speed, then energy efficiency is improved, but device complexity increases
Solution Approach 1:
The planetary gear train serves multiple functions simultaneously: it provides torque multiplication, speed variation, and acts as a mechanical coupling between the two motors. The same gear components (sun gear, planetary gears, ring gear, carrier) perform both torque transmission and speed ratio adjustment, reducing the need for separate mechanisms and thereby limiting the increase in complexity despite the added functionality.
4Use of energy by moving object
If the gear shifter physically fixes the idler gear to cut off second motor power, then energy consumption is reduced, but the system requires additional control mechanisms
Solution Approach 1:
The gear shifter mechanism extracts or removes the load path to the second motor by physically fixing the idler gear when the second motor should not be operating. This mechanical disconnection prevents energy waste from driving a motor that shouldn't be active, and uses a relatively simple locking mechanism rather than complex electronic control systems to achieve the power cutoff.
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
The system enables efficient energy use by varying torque and speed without gear shift shocks, reduces the vehicle's size and weight, and extends driving distance by optimizing motor power usage, enhancing overall driving performance and energy efficiency.
Implementation Method 1
a first gear assembly (240) including a sun gear (241) built into the housing (210) and having a main input shaft (241a) connected to the rotational shaft of the first motor (220), an inner ring gear (242) arranged to surround the sun gear (241) in a circumferential direction, a plurality of planetary gears (243) arranged between the sun gear (241) and the inner ring gear (242)
Data Source
AI summary
The invention of continuously variable transmission drive system for electric vehicles comprises a housing 210, a first motor 220, a second motor 230, a first gear assembly 240 including a sun gear 241 having a main input shaft 241a connected to a first motor 220, an inner ring gear 242 arranged around the sun gear 241, planetary gears 243 arranged between the sun gear 241 and the inner ring gear 242, and a carrier 244 having an output shaft 244a connected to the shafts of the planetary gears 243, and a second gear assembly 250 including a sub-drive gear 251 having a sub-input shaft 251a connected to a second motor 230, an outer ring gear 252 forming one body with the outer side of the inner ring gear 242, and an idler gear 253 transmitting the driving force of the second motor 230 to the outer ring gear 252.