Hybrid Vehicle Mode Switching for Gradient-Based Deceleration
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Solution Overview
Problem
Hybrid electric vehicles face challenges in providing a stable feeling of deceleration while descending a downward slope, as existing regeneration control systems do not effectively utilize engine braking to provide a sensory feedback of deceleration to the driver, leading to potential battery overcharging and fluctuations in deceleration sensation.
Innovation Solution
Incorporating an internal combustion engine, a motor-generator, and a control system that uses an inclination sensor to determine the road gradient and switch between electric vehicle (EV) and engine (ENG) driving modes based on the gradient, ensuring the internal combustion engine provides braking force during ENG driving, thereby providing a consistent auditory feedback of deceleration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If regeneration control is performed by activating the motor as a generator during deceleration, then the battery can be charged from regeneration energy, but the battery may become charged full and prevent regenerative braking from being performed on downward slopes
Solution Approach 1:
The control portion changes the operational parameters of the motor by switching between generator mode (for charging) and motor mode (for driving). When the battery reaches full charge on downward slopes, the system transitions from regenerative braking to engine-driven mode, adjusting the parameter of energy recovery to prevent battery overcharging while maintaining deceleration capability.
Solution Approach 2:
The system dynamically switches between different driving modes (EV mode, ENG mode, and hybrid mode) based on real-time conditions including battery charge state and vehicle speed. This dynamic adaptation allows the system to optimize energy recovery while ensuring regenerative braking remains available when needed, resolving the contradiction between charging efficiency and braking availability.
2Use of energy by moving object
If the motor operates as a generator for regenerative braking on downward slopes, then energy can be recovered, but the driver cannot obtain a feeling of deceleration through hearing
Solution Approach 1:
The system merges the functions of energy recovery and driver feedback by combining motor-generator operation with engine operation. When regenerative braking is active, the engine can simultaneously operate to provide auditory feedback, creating a hybrid mode that achieves both energy recovery and maintains driver awareness of deceleration through the engine sound.
Solution Approach 2:
The engine acts as an intermediary that provides auditory feedback to the driver during regenerative braking events. When the motor operates as a generator, the engine's operational sound serves as a mediator to communicate deceleration status to the driver, compensating for the lack of traditional brake noise while maintaining energy recovery.
3Reliability
If the battery state of charge is managed to prevent overcharging, then regenerative braking can be maintained, but fluctuations in deceleration sensation occur
Solution Approach 1:
The system maintains continuous useful action by seamlessly transitioning between different power sources. When the battery approaches full charge, the engine smoothly takes over to provide driving force, ensuring continuous deceleration without interruption. This continuity prevents fluctuations in deceleration sensation while maintaining the ability to perform regenerative braking when the battery has capacity.
Solution Approach 2:
The control portion anticipates battery charge state changes and proactively adjusts the driving mode before regenerative braking becomes unavailable. By monitoring battery state of charge in advance and switching to engine-driven mode before the battery reaches full capacity, the system cushions against the potential disruption to deceleration sensation, maintaining stability throughout the transition.
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 allows drivers to experience a stable and sporty feeling of deceleration by maintaining the ENG driving mode on downward slopes, preventing battery overcharging and reducing fluctuations in deceleration sensation, while also managing the state of charge of the battery.
Implementation Method 1
a regeneration control apparatus activates a motor to operate as a generator when the hybrid electric vehicle which uses an engine and the motor as power sources is decelerated to charge a motor driving battery based on regeneration energy
Implementation Method 2
the internal combustion engine provides braking force when the hybrid electric vehicle which is running on the second driving is decelerated
Data Source
AI summary
A hybrid electric vehicle including a gradient acquiring portion which acquires a gradient of a road surface on which the vehicle is running, and a control portion which determines whether the vehicle runs on a first driving by means of power from the motor by releasing the engagement and disengagement portion, or on a second driving by means of power from at least the internal combustion engine by applying the engagement and disengagement portion. The control portion restricts a switch from the second driving to the first driving when the gradient of the downward slope is equal to or greater than a threshold value. The control portion holds the second driving when the switch from the second driving to the first driving is restricted, even though the control portion obtains a request for a switch to the first driving while the vehicle runs the downward slope on the second driving.