Hybrid Vehicle Deceleration Control Under Fuel Cut Restriction
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Solution Overview
Problem
In hybrid vehicles, restricting fuel cut to maintain high deceleration during downhill control can increase the load on the motor, leading to potential overheating and inefficiencies.
Innovation Solution
A control device that includes a deceleration control unit, fuel cut control unit, downhill control unit, and deceleration limit unit to manage deceleration by restricting or permitting fuel cut based on conditions, and limiting deceleration to prevent motor overload, with additional features to estimate filter temperature and notify the driver.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If fuel cut is restricted to maintain smooth deceleration, then deceleration smoothness is improved, but motor load increases
Solution Approach 1:
The control device changes the deceleration parameter dynamically by limiting deceleration to a predetermined value when fuel cut is restricted, rather than allowing unrestricted deceleration. This parameter adjustment resolves the contradiction by accepting reduced deceleration performance in exchange for maintaining smooth operation without excessive motor load.
2Speed
If downhill control is executed to increase deceleration, then deceleration performance is improved, but motor load increases
Solution Approach 1:
The control device applies deceleration limitation as a parameter change to resolve the contradiction. When downhill control is executed with fuel cut restriction, the deceleration is capped at a predetermined level, preventing excessive motor load while maintaining controlled deceleration performance.
3Force
If deceleration is limited when fuel cut is restricted, then motor load is reduced, but deceleration performance decreases
Solution Approach 1:
The control device applies partial action by implementing deceleration limitation only under specific conditions (when fuel cut is restricted), rather than applying it universally. This allows the system to maintain normal deceleration performance when fuel cut is permitted, while only limiting deceleration when necessary to protect the motor.
Data Source
AI summary
A control device for a hybrid vehicle, includes a deceleration control unit configured to control an engine and a motor as traveling power sources to control deceleration of the hybrid vehicle, a fuel cut control unit configured to restrict or permit fuel cut in the engine based on establishment or non-establishment of a predetermined condition, a downhill control unit configured to execute downhill control for increasing deceleration during downhill traveling higher than deceleration during flat traveling, and a deceleration limit unit configured to limit deceleration in restricting the fuel cut and in executing the downhill control lower than deceleration in permitting the fuel cut and in executing the downhill control.