Hybrid Drivetrain Reverse Gear Braking Torque Control
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Solution Overview
Problem
Conventional clutch mechanisms in hybrid vehicles lead to increased fuel consumption, wear, and space requirements, along with friction losses, when braking, as they disconnect the input shaft from the gearbox, and existing solutions do not efficiently regenerate brake energy.
Innovation Solution
A method that engages reverse gear during forward driving to allow the electric machine to brake with full torque, using a planetary gear system where the electric machine is connected to the ring gear, reducing weight and size, and allowing maximum brake energy regeneration without additional gear changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a conventional clutch mechanism is used to disconnect the input shaft from the gearbox during gearchanging, then the vehicle can change gears, but this results in heating of the clutch discs, increased fuel consumption, and wear of the clutch discs
Solution Approach 1:
The patent removes the conventional clutch mechanism from the drivetrain and replaces it with a planetary gear system that enables seamless gearchanging without mechanical disconnection. This extraction eliminates the source of energy loss (clutch disc friction and heating) while maintaining the essential function of gear changing through continuous planetary gear ratio transitions.
Solution Approach 2:
The patent substitutes the mechanical clutch-based gearchanging system with an electrically-controlled planetary gear system. The electric machine controls the planetary gear ratios without requiring mechanical disconnection, replacing the friction-based clutch mechanism with an electrically-actuated system that avoids energy loss through friction and heating.
2Ease of operation
If a conventional clutch mechanism is used for gearchanging, then gear changes can be made, but this causes wear of the clutch discs and requires regular maintenance
Solution Approach 1:
The patent extracts the clutch mechanism from the system entirely, eliminating the wear-prone friction surfaces. The planetary gear system performs gearchanging through controlled ratio changes without mechanical disengagement, removing the source of clutch disc wear and associated maintenance requirements.
Solution Approach 2:
The mechanically-intensive clutch-based gearchanging is replaced with an electrically-controlled planetary gear system. This substitution eliminates the wear mechanism inherent in clutch discs while maintaining reliable gear changing capability through electronic control of the planetary gear ratios.
3Ease of operation
If a conventional clutch mechanism is used, then the vehicle can disconnect the input shaft, but this requires a comparatively large space and increases the vehicle weight
Solution Approach 1:
The patent removes the heavy clutch mechanism from the drivetrain, eliminating unnecessary weight. The planetary gear system provides the same functional capability (input shaft disconnection/gearchanging) in a more compact and lighter configuration, directly reducing vehicle mass.
Solution Approach 2:
The patent merges the gearchanging function with the planetary gear system, combining multiple functions (gear ratio changes, input shaft disconnection, and torque transmission) into a single integrated mechanism. This consolidation eliminates the need for separate clutch components, reducing overall weight and space requirements.
4Ease of operation
If a conventional clutch mechanism is used, then the vehicle can change gears, but friction losses are created during the gearchanging process
Solution Approach 1:
The patent replaces the friction-based clutch mechanism with an electrically-controlled planetary gear system. This substitution eliminates friction losses by using electrically-actuated torque transfer through the planetary gears instead of friction-based clutch engagement, significantly reducing energy loss during gearchanging operations.
5Force
If forward gear is used during braking with electric machine, then the vehicle can brake, but the combustion engine gets increased rotational speed reducing braking efficiency
Solution Approach 1:
The patent inverts the conventional approach by using reverse gear during forward braking operations. This inversion allows the electric machine to operate as a generator at optimal speeds while the planetary gear system manages the torque direction, enabling full electric braking torque without increasing combustion engine speed and maintaining braking efficiency throughout the braking process.
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 approach reduces weight and size, maintains standardized interfaces, increases brake torque, and efficiently regenerates kinetic energy during braking, minimizing fuel consumption and wear, while enabling purely electric driving after braking.
Implementation Method 1
When the vehicle is braked the electric machine generates electrical energy which may be stored
Implementation Method 2
the output shaft of the combustion engine, the rotor of the electric machine and the input shaft of the gearbox are interconnected by a planetary gear
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
A method for braking a vehicle driving forward towards stop, said vehicle having a propulsion system comprising a combustion engine with an output shaft (2a), a gearbox (3) with an input shaft (3a), an electric machine (9) comprising a stator and a ro¬ tor, and a planetary gear comprising a sun gear (10), a ring gear (1 1 ) and a planet wheel carrier (12). When braking the vehicle a reverse gear of the gearbox is engaged and the electric machine is controlled to apply brake torque requested to the input shaft of the gearbox.