Hybrid Vehicle Fuel Cut Control via Motor Reaction Torque
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Solution Overview
Problem
Current fuel cut operations in hybrid electric vehicles are limited to restricted transmission regions, causing sudden engine torque changes that result in vehicle shaking and reduced fuel efficiency, especially at lower speeds and RPMs.
Innovation Solution
A control method that enables fuel cut operations in a wider transmission region by using a hybrid control unit to transmit enabling and cancellation signals to the engine control unit, coupled with motor reaction control to smooth torque input to the continuously variable transmission, thereby prolonging the fuel cut period and reducing torque impacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the fuel cut operation is cancelled at about 1500 RPM to revive the engine, then the engine can restart, but a sudden change in engine torque occurs causing vehicle shaking
Solution Approach 1:
The motor applies a preliminary counteracting torque before and during engine restart to offset the sudden torque change from fuel cut cancellation. This preliminary anti-action prevents the harmful effect of vehicle shaking while maintaining reliable engine restart capability.
Solution Approach 2:
The motor acts as an intermediary between the engine and the transmission system during fuel cut cancellation. By controlling the motor torque, it mediates the sudden torque change from the engine, smoothing the torque transmission to the wheels and eliminating vehicle shaking.
2Use of energy by moving object
If the fuel cut period is prolonged at lower speed and RPM to improve fuel efficiency, then fuel efficiency improves, but the impact at the moment when fuel cut operation is cancelled increases
Solution Approach 1:
The motor applies counteracting torque in advance of fuel cut cancellation to prepare for and offset the upcoming torque impact. This preliminary anti-action allows the fuel cut period to be prolonged for improved fuel efficiency while preventing harmful torque impacts during cancellation.
Solution Approach 2:
The control system continuously monitors engine torque and motor torque to dynamically adjust the motor's counteracting torque during fuel cut operation and cancellation. This feedback control ensures that the motor torque precisely offsets the engine torque changes, allowing prolonged fuel cut periods without harmful impacts.
3Use of energy by moving object
If the fuel cut operation is performed in a wider transmission region, then fuel efficiency improves, but the sudden change in engine torque occurs more frequently
Solution Approach 1:
The motor serves as an intermediary that continuously compensates for engine torque changes across a wider transmission region. By actively controlling motor torque to offset engine torque variations, it enables extended fuel cut operation across more gear ratios and vehicle speeds without causing frequent harmful torque changes.
Data Source
AI summary
The present invention provides a control method for a hybrid electric vehicle According to a control method of the present invention, the fuel efficiency is improved by extending a fuel cut operation in a wider transmission range and the impact caused by the extended fuel cut operation is reduced by reaction control of a motor operating in the opposite direction to engine torque.