ISG Shift Control Using Mechanical Oil Pump Pressure Adjustment
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Solution Overview
Problem
ISG vehicles using mechanical oil pumps experience a long time to supply hydraulic pressure to the solenoid after engine restart, resulting in variations in shift time due to the complete loss of hydraulic pressure when the engine is turned off.
Innovation Solution
A shift control method and apparatus that determines if the vehicle satisfies the ISG learning condition, measures the shift time from idling to restart, compares it with a reference time, and adjusts the oil pressure supplied to the transmission solenoid accordingly to minimize shift time variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If a mechanical oil pump is used in an ISG vehicle, then cost, weight, and fuel efficiency are improved, but hydraulic pressure supply time increases and shift time variation occurs
Solution Approach 1:
The control unit performs preliminary action by advancing the oil pump operation timing before the actual shift execution. When a shift command is received, the control unit activates the oil pump in advance to build up hydraulic pressure before the shift actuator needs to operate, thereby reducing the shift time variation caused by the mechanical oil pump's delayed pressure response.
2Ease of manufacture
If a mechanical oil pump is used in an ISG vehicle, then cost and fuel efficiency are improved, but shift time control precision deteriorates
Solution Approach 1:
The control unit implements feedback control by monitoring the actual shift time and comparing it with the target shift time. Based on this comparison, the control unit adjusts the oil pump operation duration and timing to compensate for the mechanical oil pump's inherent delays, thereby maintaining precise shift time control despite using a cost-effective mechanical pump.
3Adaptability or versatility
If hydraulic pressure is completely lost in the solenoid when the engine is turned off, then the ISG mode function is achieved, but the time to supply hydraulic pressure increases after restart
Solution Approach 1:
The control unit performs preliminary action by activating the oil pump before the shift operation when the engine is restarted after ISG mode. This advance activation ensures hydraulic pressure is built up in the solenoid before the shift actuator needs to operate, compensating for the complete pressure loss that occurs during engine shutdown and reducing the delay after restart.
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 shift time variations in ISG vehicles using mechanical oil pumps, improving restart efficiency and potentially reducing weight and costs compared to electrical oil pumps.
Implementation Method 1
a constant hydraulic pressure is supplied to the solenoid of a transmission by means of an electrical oil pump
Data Source
AI summary
A shift control method and apparatus for a vehicle is described. The shift control method for a vehicle having an oil pump includes determining whether the vehicle satisfies an Idle Stop and Go (ISG) learning condition, measuring, when the vehicle satisfies the ISG learning condition, a shift time of a transmission when a driving state of the vehicle is changed from an idling state to a restart state, comparing the measured shift time with a predetermined reference shift time, and adjusting a pressure of oil supplied to a solenoid of the transmission from the oil pump according to the compared result. Thus, it is possible to reduce a variation in shift time required when the ISG vehicle using a mechanical oil pump in place of an electrical oil pump is restarted.