Hybrid Vehicle Catalyst Warming Using Regenerative Braking Power
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Solution Overview
Problem
In hybrid vehicles, the catalyst temperature drops during engine combustion operation stoppages, such as during gentle downhill driving, leading to reduced fuel efficiency when traditional Electrical Heated Catalyst (EHC) systems use electric power from the power storage device, causing inefficiencies due to power conversion losses.
Innovation Solution
A control system that utilizes regenerative power from the rotating electric machine to maintain catalyst temperature by activating the warming-up device when specific conditions are met, such as engine stoppage and regenerative braking, ensuring the catalytic activation temperature is maintained without reducing overall vehicle efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the EHC is driven using electric power from the power storage device, then the catalyst temperature can be maintained at a predetermined temperature, but overall vehicle efficiency is reduced due to power conversion loss
Solution Approach 1:
The system uses regenerative power generated by the rotating electric machine during vehicle deceleration to directly drive the warming-up device, making the system self-sufficient by utilizing its own generated energy rather than drawing from the power storage device. This eliminates the power conversion loss associated with charging and discharging the power storage device while maintaining catalyst temperature.
2Use of energy by moving object
If the engine combustion operation is stopped during gentle downhill driving, then fuel consumption is reduced, but the catalyst temperature gradually decreases below activation temperature
Solution Approach 1:
The system proactively maintains catalyst temperature by utilizing regenerative power during deceleration events before the catalyst temperature drops below activation temperature. By anticipating the temperature drop that occurs during engine stoppage and using available regenerative power to prevent it, the system ensures the catalyst remains ready for immediate operation when the engine restarts.
3Power
If regenerative braking is used during gentle downhill driving, then driving torque is reduced, but electric power is generated that can be used to warm up the catalyst
Solution Approach 1:
The system converts the otherwise wasted energy during regenerative braking into a beneficial resource for catalyst warming. By capturing the electric power generated during deceleration and directing it to the warming-up device, the system transforms a situation with reduced driving torque into an opportunity to maintain catalyst temperature without consuming additional fuel or energy from the power storage device.
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 ensures catalytic activation temperature is maintained using regenerative power, preventing reductions in vehicle efficiency and minimizing heat loss, thus improving energy balance and reducing power conversion losses.
Implementation Method 1
the control device causes the warming-up device to raise the temperature of the catalyst using generated electric power by the rotating electric machine
Implementation Method 2
The rotating electric machine is coupled to a driving wheel of the vehicle to produce driving force for causing the vehicle to run and capable of generating electric power by rotary force of the driving wheel
Data Source
AI summary
A hybrid vehicle in which at least two shift ranges can be selected for a single running direction includes an engine, a motor generator, an EHC raising the temperature of a catalyst for cleaning up an exhaust gas from the engine, and an ECU. While the vehicle is running, if the engine is stopped and, of the two shift ranges, a shift range where larger decelerating force is produced by regenerative braking of the motor generator has been selected, the ECU causes the EHC to raise the temperature of the catalyst using electric power generated by the motor generator.