Hybrid Gearbox Torque Control via Epicyclic Coupling

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Solution Overview

Problem

Existing gearboxes in hybrid vehicles face challenges such as torque interruption during gear changes, high weight and cost due to conventional clutch mechanisms, and limited reliability and dependability, especially in heavy vehicles requiring multiple gear steps and regenerative braking systems.

Innovation Solution

A gearbox design utilizing two epicyclic gears with controlled coupling units that allow for seamless torque transfer and electrical operation, eliminating the need for conventional clutches, and incorporating cogged wheel drives for compact, reliable, and dependable operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional clutch mechanisms are used for gear changes, then gear changing is possible, but torque interruption occurs during gear changes

Engineering Contradiction:

Improvecontinuous torque transmissionVSAvoidclutch mechanism

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent removes the conventional clutch mechanism from the hybrid vehicle gearbox. By extracting this component, the invention eliminates torque interruption during gear changes while also reducing device complexity and cost. The electric machine takes over the function previously performed by the clutch, enabling seamless gear transitions without mechanical disengagement.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the mechanical clutch system with an electrically controlled system. The electric machine, controlled by a control unit, manages torque transmission and gear changes through electrical signals rather than mechanical engagement. This substitution eliminates the inherent torque interruption of mechanical clutches while maintaining gear changing capability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If conventional clutch mechanisms are used, then gear changes can be performed, but weight and cost increase

Engineering Contradiction:

Improvegear changing capabilityVSAvoidclutch mechanism weight

Core Design Contradiction:

ReliabilityVSWeight of moving object

Solution Approach 1:

By removing the clutch mechanism entirely, the patent eliminates its weight from the vehicle. The extraction of this heavy mechanical component directly reduces the overall weight of the moving object while preserving gear changing functionality through the electric machine's control system.

Inventive Principle:

Principle #2Taking out (Extraction)

3Adaptability or versatility

If multiple gear steps are implemented for heavy vehicles, then adaptability improves, but device complexity increases

Engineering Contradiction:

Improvegear step optionsVSAvoidgearbox structure

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent makes the electric machine multi-functional, enabling it to perform both torque transmission and gear changing control across multiple gear steps. This universal approach allows heavy vehicles to access multiple gear ratios without proportionally increasing mechanical complexity, as the electrically controlled system manages all gear transitions centrally.

Inventive Principle:

Principle #6Universality (Multi-functionality)

4Use of energy by moving object

If regenerative braking is implemented, then energy recovery is achieved, but reliability of energy storage system decreases due to lifespan limitations

Engineering Contradiction:

Improveenergy recoveryVSAvoidenergy storage system lifespan

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The control unit continuously monitors the state of the energy storage system and adjusts the regenerative braking operation accordingly. By implementing feedback control, the system optimizes energy recovery while preventing conditions that would degrade the energy storage system, thereby extending its lifespan and improving overall reliability.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS10767736B2Gearbox for a hybrid powertrain and method to control such a gearbox

Publication Date: 2020.09.08 SCANIA CV AB

AI summary

A gearbox having an input shaft (8) and an output shaft (20); a first epicyclic gear (10) connected to the input shaft (8); a second epicyclic gear (12) connected to the first epicyclic gear (10); a first electrical machine (14) connected to the first epicyclic gear (10); a second electrical machine (16) connected to the second epicyclic gear (12); a first main shaft (34) connected to the first epicyclic gear (10); a second main shaft (36) connected to the second epicyclic gear (12). A first coupling unit (56) disengagingly connects two rotatable components (22, 26, 50) at the first epicyclic gear (10), and a second coupling unit (58) disengagingly connects two rotatable components (28, 32, 51) at the second epicyclic gear (12), such that at least one of the rate of revolution and the torque at the first and the second main shafts (34, 36) can be influenced by controlling at least one of the first and the second coupling units (56, 58) to a condition of the rotatable components (22, 26, 50; 28, 32, 51) that is engaged or disengaged. Also a vehicle (1) having such a gearbox (2), a method to control such a gearbox (2), a computer program (P) to control a gearbox, and a computer program product comprising program code for an electronic control unit (48) or another computer (53) in order to implement the method.