Electric Vehicle Transmission with Variable Ratios for Motor Efficiency

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Solution Overview

Problem

Conventional electric vehicle driving systems face inefficiencies due to mismatched torque and rotational speed characteristics, leading to high power consumption and reduced driving range, especially under low-speed and high-speed conditions, making them unsuitable for complex driving conditions.

Innovation Solution

A driving system for electric vehicles featuring a transmission with multiple units, including a first and second transmission unit with distinct ratios, allowing selective power transmission to match torque and rotational speed characteristics, and a hydraulic system to engage and disengage clutches for gear shifting, optimizing energy use and range.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a reducer with a constant transmission ratio is used, then the structure is simple, but the driving motor efficiency is low under different driving conditions

Engineering Contradiction:
Improvetransmission structureVSAvoiddriving motor efficiency
Core Design Contradiction:
Device complexityVSUse of energy by moving object

Solution Approach 1:

The patent applies dynamics by replacing the constant transmission ratio with a variable transmission ratio that can be adjusted according to driving conditions. The transmission system switches between different transmission units (first transmission unit for low speed/high torque, second transmission unit for high speed/low torque) to match the driving motor's optimal efficiency range under varying operational requirements.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the transmission ratio parameter dynamically by providing at least two transmission units with different transmission ratios. The control system selects the appropriate transmission unit based on driving conditions, thereby changing the transmission ratio parameter to maintain the driving motor within its high-efficiency operating range.

Inventive Principle:
Principle #35Parameter changes

2Device complexity

If a single transmission ratio is used, then the device complexity is low, but the adaptability to different driving conditions is poor

Engineering Contradiction:
Improvetransmission systemVSAvoiddriving condition adaptability
Core Design Contradiction:
Device complexityVSAdaptability or versatility

Solution Approach 1:

The patent segments the transmission system into at least two separate transmission units, each with a different transmission ratio. The first transmission unit is optimized for low-speed high-torque conditions, while the second transmission unit is optimized for high-speed low-torque conditions. This segmentation allows the system to adapt to different driving conditions by selecting the appropriate transmission unit.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The transmission system achieves multi-functionality by incorporating multiple transmission units that can handle different driving scenarios. The system can switch between transmission units to satisfy both low-speed high-torque requirements (starting, climbing) and high-speed low-torque requirements (cruising), making it universally applicable to various driving conditions.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Duration of action of moving object

If the driving motor operates outside optimal efficiency range, then the driving range is extended, but the power consumption increases

Engineering Contradiction:
Improvedriving rangeVSAvoidpower consumption
Core Design Contradiction:
Duration of action of moving objectVSUse of energy by moving object

Solution Approach 1:

The control system monitors driving conditions and feedback signals to determine the appropriate transmission unit to engage. By continuously adjusting the transmission ratio based on real-time driving conditions, the system keeps the driving motor operating within its optimal efficiency range, thereby reducing power consumption and extending the driving range.

Inventive Principle:
Principle #23Feedback

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 solution enhances the efficiency of the driving motor under various conditions, reduces energy consumption, and extends the driving range by matching torque and speed characteristics, enabling the electric vehicle to handle complex driving scenarios effectively.

Implementation Method 1

a hydraulic system to engage and disengage clutches for gear shifting

Methodology Applied
Scientific EffectHydraulic pressure: Pressure Increase

Data Source

PatentEP2619025B1Driving system for electric vehicle
Publication Date: 2017.11.22 BYD CO LTD
  • EP2619025B1 patent drawingFigure 1
  • EP2619025B1 patent drawingFigure 2
  • EP2619025B1 patent drawingFigure 3

AI summary

A driving system of an electric vehicle is provided. The driving system comprises: a driving motor (1); a transmission which comprises an input shaft (2), a countershaft (13), an output shaft (5), a first transmission unit (Bl), a first clutch (15), a second transmission unit (B2) and a second clutch (11); and a hydraulic system connected to the first clutch (15) to engage or disengage the first clutch (15) and connected to the second clutch (11) to engage or disengage the second clutch (11).