Integrated Motor-Transmission Housing With Shared Cooling Lubrication

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Solution Overview

Problem

Existing vehicle electric assemblies have a bulky and inefficient structure, leading to high weight, increased costs, and reduced endurance capabilities due to large, separate motor and transmission assemblies with inadequate cooling and space utilization.

Innovation Solution

An integrated electric assembly design where the motor and transmission share a compact box assembly, utilizing a mounting plate for cooling lubrication and an oil pump to circulate cooling lubricating liquid, reducing the need for multiple components and bolts, and enhancing heat dissipation through a combination of liquid and air cooling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If motor assembly and transmission assembly are individually disposed and connected through bolts, then each assembly can be independently manufactured and maintained, but the overall structure becomes bulky, occupies more space, and increases weight

Engineering Contradiction:
ImproveIndependent manufacturing capabilityVSAvoidOverall assembly volume
Core Design Contradiction:
Ease of manufactureVSVolume of moving object

Solution Approach 1:

The patent combines the motor assembly and transmission assembly into a single integrated electric assembly. The motor housing and transmission housing are merged into one unified structure, eliminating the need for separate bolt connections and reducing overall volume. This merging approach maintains manufacturing feasibility while significantly compacting the assembly footprint.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The integrated electric assembly housing performs multiple functions simultaneously: it serves as both the motor housing and transmission housing, provides structural support, and facilitates cooling fluid circulation. This multi-functionality reduces the number of separate components needed while maintaining ease of manufacture through standardized production processes.

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

2Strength

If box assemblies at connection locations have relatively large wall thicknesses, then structural strength is improved, but space is wasted and the structure becomes less compact

Engineering Contradiction:
ImproveConnection location strengthVSAvoidBox assembly volume
Core Design Contradiction:
StrengthVSVolume of moving object

Solution Approach 1:

The patent applies local quality by providing thicker wall sections only at specific connection locations where strength is required, while using thinner walls in non-critical areas. This localized reinforcement maintains necessary structural strength while minimizing overall volume and improving compactness of the electric assembly.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The integrated housing design redistributes structural strength across three dimensions by creating a unified shell structure that leverages the geometry of the entire assembly rather than relying on thick walls in single locations. This dimensional optimization reduces material usage while maintaining strength.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Adaptability or versatility

If multiple separate assemblies are used, then component modularity is achieved, but the number of components increases and mounting becomes difficult

Engineering Contradiction:
ImproveComponent modularityVSAvoidMounting ease
Core Design Contradiction:
Adaptability or versatilityVSEase of operation

Solution Approach 1:

The patent merges the motor and transmission into a single integrated assembly that functions as one modular unit. This eliminates the need for multiple separate mounting operations while maintaining the adaptability benefits of modularity at the system level. The integrated assembly can be mounted as a single component, significantly simplifying installation procedures.

Inventive Principle:
Principle #5Merging (Combining)

4Adaptability or versatility

If separate motor and transmission assemblies are used, then each assembly can be optimized independently, but the overall mass increases and affects vehicle endurance

Engineering Contradiction:
ImproveIndependent optimization capabilityVSAvoidElectric assembly weight
Core Design Contradiction:
Adaptability or versatilityVSWeight of moving object

Solution Approach 1:

The patent combines motor and transmission into one integrated assembly, eliminating redundant structural components, fasteners, and cooling systems. This merging reduces overall mass while maintaining the ability to independently optimize motor and transmission designs through separate engineering processes before integration.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The integrated design allows for feedback loops in the design process where weight savings from integration can be reinvested into performance optimizations, and vice versa. This iterative optimization process continues until the best balance between independent optimization capability and minimum weight is achieved.

Inventive Principle:
Principle #23Feedback

5Device complexity

If inadequate cooling system is used, then device complexity is reduced, but heat dissipation is insufficient and reliability decreases

Engineering Contradiction:
ImproveCooling system complexityVSAvoidHeat dissipation reliability
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent merges the cooling systems for the motor and transmission into a single integrated cooling circuit. This unified cooling system uses one set of cooling channels, pumps, and fluid circulation paths to cool both components, reducing system complexity while maintaining adequate heat dissipation for both the motor and transmission through shared cooling infrastructure.

Inventive Principle:
Principle #5Merging (Combining)

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 solution results in a more compact, lightweight, and efficiently cooled electric assembly with improved reliability, stability, and reduced energy loss, enhancing the vehicle's endurance and operational efficiency.

Implementation Method 1

The cooling lubricating liquid fills the transmission holding cavity and cools the box assembly through the mounting plate

Methodology Applied
Scientific EffectHeat transfer: Conduction (thermal)

Implementation Method 2

the oil pump is disposed on the box assembly and configured to transport the cooling lubricating liquid in the transmission holding cavity to the transmission and the mounting plate

Methodology Applied
Scientific EffectFluid transport: Pump

Data Source

PatentEP3751709B1Power assembly and vehicle provided with same
Publication Date: 2023.09.06 BYD CO LTD
  • EP3751709B1 patent drawingFigure 1
  • EP3751709B1 patent drawingFigure 2
  • EP3751709B1 patent drawingFigure 3

AI summary

This application discloses an electric assembly and a vehicle having the same. The electric assembly includes: a box assembly, where an mounting plate is disposed in the box assembly, and the mounting plate divides a space within the box assembly into a motor holding cavity and a transmission holding cavity; a motor, disposed in the motor holding cavity; a transmission, disposed in the transmission holding cavity, where the motor is power-coupled to the transmission; and a cooling lubricating liquid, filling the transmission holding cavity and cooling the box assembly.