Hybrid Vehicle Deceleration Control for Delayed Engine Braking
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Solution Overview
Problem
The existing method for managing the deceleration phase of hybrid motor vehicles leads to early engagement of the heat engine, resulting in excessive fuel consumption and emissions due to premature application of braking torque by the thermal engine.
Innovation Solution
A method that delays the application of braking torque by the heat engine by accounting for mechanical losses, allowing the electric motor to recharge the battery first, and then engaging the heat engine only when the battery is fully recharged and additional mechanical losses are considered, ensuring the desired braking torque is maintained.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the heat engine is started and coupled to the gearbox as soon as the battery reaches maximum recharge capacity, then the desired braking torque can be maintained, but fuel consumption and emissions increase due to premature engine engagement
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing the mechanical loss torque value before the deceleration phase begins. The computer pre-determines the sum of mechanical losses (friction, pumping, auxiliary components) and prepares this data for use during braking, enabling optimized engine engagement timing without real-time calculation delays
Solution Approach 2:
The patent implements feedback by continuously monitoring the battery's charge state and comparing it against the maximum recharge capacity threshold. The computer receives feedback on battery charge level and uses this information to determine the precise moment when regenerative braking should transition to thermal engine braking, ensuring optimal engagement timing
2Force
If the heat engine is engaged early to provide braking torque, then the braking torque requirement is met, but carbon dioxide emissions increase due to unnecessary fuel usage
Solution Approach 1:
The computer pre-calculates the threshold braking torque value (sum of mechanical losses and previously applied electric torque) before deceleration begins. This preliminary preparation allows the system to make an informed, delayed engagement decision that minimizes emissions while ensuring braking torque requirements are met
Solution Approach 2:
The patent changes the engagement parameter from a simple battery charge threshold to a composite threshold that includes both battery charge state and calculated mechanical loss torque. This parameter modification allows the system to delay engine engagement until the precise moment when it becomes necessary, reducing emissions
3Loss of energy
If the electric motor operates in generator mode to recharge the battery during deceleration, then energy recovery is achieved, but the braking torque capacity is limited by battery recharge capacity
Solution Approach 1:
The patent merges two different braking mechanisms - regenerative braking (electric motor in generator mode) and thermal engine braking - into a coordinated hybrid braking system. The system seamlessly transitions from electric to thermal braking when the battery reaches maximum charge, combining the energy recovery benefits of regenerative braking with the unlimited torque capacity of thermal engine braking
Solution Approach 2:
The computer acts as an intermediary that manages the transition between regenerative and thermal braking modes. It monitors battery charge state, calculates optimal engagement timing considering mechanical losses, and controls the engine interconnection clutch to seamlessly switch between the two braking mechanisms, ensuring continuous braking torque delivery
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 fuel consumption and carbon dioxide emissions by optimizing the timing of heat engine engagement during deceleration phases, thereby minimizing unnecessary fuel usage and emissions.
Implementation Method 1
the electric motor operating in generator mode to recharge the battery
Implementation Method 2
the heat engine by starting and coupling the heat engine to the gearbox
Data Source
Figure 1~2
Figure 3
AI summary
The invention relates to a method for managing a deceleration phase of a motor vehicle (10') comprising a traction chain (10) which comprises an electric motor (12) and a heat engine (11), the method comprising, during a deceleration phase: - a step of applying a first resistive torque corresponding to a negative torque of the electric motor (12) operating in generator mode to recharge the battery (24), then - a step of applying a second resistive torque corresponding to a negative torque of the heat engine (11) by controlling the motor interconnection clutch (16), - the second resistive torque being applied as soon as a braking torque is reached which is equal to a sum of a torque previously applied by the electric motor (12), when a maximum recharging capacity of the battery (24) has been reached, and a mechanical loss torque of the heat engine (11).