Automatic Transmission Idle Stop Control via Gradient Threshold Adjustment
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Solution Overview
Problem
Conventional automatic transmissions face challenges in supplying sufficient hydraulic pressure to the gear corresponding to the starting shift position, especially when the road surface gradient is large and oil temperature is either low or high, leading to potential vehicle backward movement during idle stop control.
Innovation Solution
An automatic transmission system that includes an electrical oil pump, oil temperature detection, gradient threshold value setting, and idle stop prohibition based on detected oil temperature and road surface gradient, adjusting the gradient threshold value to prevent excessive oil leakage and ensure hydraulic pressure supply.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If idle stop control is executed when road surface gradient is large, then fuel economy is improved, but hydraulic pressure cannot be sufficiently supplied to the gear causing vehicle backward movement
Solution Approach 1:
The patent applies parameter changes by adjusting the gradient threshold value based on oil temperature. When oil temperature is low or high, the gradient threshold is reduced, which dynamically changes the operating parameters to prevent hydraulic pressure insufficiency while still allowing idle stop control under appropriate conditions, thus resolving the contradiction between fuel economy and hydraulic pressure supply reliability
Solution Approach 2:
The patent implements feedback by detecting oil temperature and using it to adjust the gradient threshold value for idle stop control permission. This closed-loop control ensures that idle stop is only permitted when hydraulic pressure can be sufficiently supplied, preventing vehicle backward movement while maximizing fuel economy opportunities
2Loss of energy
If gradient threshold value is set high to allow more idle stop control, then fuel economy improves, but vehicle startability deteriorates when oil temperature is low or high
Solution Approach 1:
The patent dynamically changes the gradient threshold parameter based on oil temperature conditions. When oil temperature is within the normal range (40°C to 100°C), a higher threshold allows more idle stop opportunities for fuel economy. When oil temperature is low (below 40°C) or high (above 100°C), the threshold is reduced to ensure reliable hydraulic pressure supply, thus maintaining vehicle startability while maximizing fuel economy
3Quantity of substance
If oil temperature is low or high, then oil leakage increases, but hydraulic pressure supply becomes insufficient causing idle stop control to fail
Solution Approach 1:
The patent takes preliminary action by detecting oil temperature before permitting idle stop control. When oil temperature is low or high, the system proactively reduces the gradient threshold or prohibits idle stop control before hydraulic pressure insufficiency occurs, preventing control failure rather than reacting after the problem occurs
Solution Approach 2:
The patent uses oil temperature detection as feedback to adjust idle stop control permission. The detected oil temperature information is used to dynamically set the gradient threshold, creating a closed-loop control that prevents hydraulic pressure insufficiency and idle stop control failure under extreme temperature conditions
Data Source
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AI summary
When the temperature of oil supplied to an electrical oil pump is detected and the oil temperature is lower or higher than normal oil temperature, a gradient threshold value smaller than that at normal oil temperature is set, a gradient of a road surface on which a vehicle is stopped is detected, and an idle stop is prohibited when the detected gradient of the road surface is larger than the set gradient threshold value.