Compact Hybrid Transmission with Offset Electric Machine

Solution Overview

Problem

Existing hybrid transmissions for motor vehicles are too large in dimensions, particularly in length and transverse size, making them unsuitable for small vehicles, and lack flexibility in gear ratio independence between thermal and electric sources.

Innovation Solution

The hybrid transmission design features a solid primary shaft connected to the heat engine and a concentric hollow primary shaft connected to the electric machine, with a single differential pinion on the secondary shaft, allowing for independent gear ratios and a more compact layout by removing one differential pinion, and includes a second electric machine coupled to the transfer shaft for enhanced control and flexibility.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a conventional hybrid transmission architecture with two secondary shafts and multiple differential pinions is used, then the transmission can provide multiple thermal and hybrid gears, but the total length and transverse size become too large for small vehicles

Engineering Contradiction:

Improvegear ratio flexibilityVSAvoidtransmission length

Core Design Contradiction:

Adaptability or versatilityVSLength of stationary object

Solution Approach 1:

The patent merges the functions of two secondary shafts into a single secondary shaft. The transfer shaft couples the primary shafts and transfers movement to the single secondary shaft, eliminating the need for a second secondary shaft while maintaining the ability to provide multiple thermal and hybrid gears through the coupling devices on the primary shafts.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent removes one differential pinion from the conventional architecture. By using a single secondary shaft with one differential pinion instead of two secondary shafts with two pinions, the transverse size and front overhang are reduced, making the transmission suitable for small vehicles while maintaining gear ratio flexibility through alternative coupling mechanisms.

Inventive Principle:

Principle #2Taking out (Extraction)

2Adaptability or versatility

If a conventional hybrid transmission architecture is used, then multiple gears can be provided, but the transverse size and front overhang are too large

Engineering Contradiction:

Improvegear ratio flexibilityVSAvoidtransmission transverse size

Core Design Contradiction:

Adaptability or versatilityVSArea of stationary object

Solution Approach 1:

The patent merges the functions of two secondary shafts into a single secondary shaft. The transfer shaft couples the primary shafts and transfers movement to the single secondary shaft, eliminating the need for a second secondary shaft while maintaining the ability to provide multiple thermal and hybrid gears through the coupling devices on the primary shafts.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent removes one differential pinion from the conventional architecture. By using a single secondary shaft with one differential pinion instead of two secondary shafts with two pinions, the transverse size and front overhang are reduced, making the transmission suitable for small vehicles while maintaining gear ratio flexibility through alternative coupling mechanisms.

Inventive Principle:

Principle #2Taking out (Extraction)

3Adaptability or versatility

If the electric machine and heat engine are coupled through a complex multi-shaft architecture, then torque can be combined in hybrid mode, but the device complexity increases

Engineering Contradiction:

Improveoperational mode flexibilityVSAvoidtransmission architecture complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent merges the functions of two secondary shafts into a single secondary shaft. The transfer shaft couples the primary shafts and transfers movement to the single secondary shaft, eliminating the need for a second secondary shaft while maintaining the ability to provide multiple thermal and hybrid gears through the coupling devices on the primary shafts.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The transfer shaft serves multiple functions: it couples the solid primary shaft to the hollow primary shaft, transfers movement from the primary shafts to the secondary shaft, and enables both thermal and hybrid gear ratios. This multi-functionality reduces the number of separate components needed while maintaining operational mode flexibility.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentEP3160786B1Hybrid transmission with offset electric machine and method for controlling gear changes

Publication Date: 2022.03.23 RENAULT SA

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AI summary

The invention relates to a hybrid transmission for a motor vehicle provided with a heat engine and a main drive electric machine (8), comprising two concentric input shafts (3, 4) connected to the crankshaft (1) of the heat engine and to the electric machine (8) with no disconnect clutch, an output shaft (5) connected to the wheels of the vehicle by a differential (7), and a shaft (6) for transferring movement from an input shaft (3) to the output shaft (5) and for coupling the input shafts (3, 4), characterised in that the electric machine (8) is arranged at the end opposite the input shafts (3, 4) relative to the heat engine.