Hydraulic Cut-Off Valve Line Pressure Detection
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Solution Overview
Problem
Existing hydraulic control devices for automatic transmissions face challenges in reliably confirming the operation of engagement mechanisms, particularly when a source pressure cut-off valve is stuck, which can lead to abnormal conditions and potential failures.
Innovation Solution
A hydraulic control device incorporating a cut-off valve with a valve element that switches between positions to control the supply of hydraulic fluid to frictional engagement mechanisms and a line pressure detection unit, allowing for detection of line pressure and confirmation of the cut-off valve's operation, thereby enabling fail-safe mechanisms and reducing additional costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a source pressure cut-off valve is added to prevent linear solenoid valve failure, then system reliability is improved, but device complexity increases
Solution Approach 1:
The patent combines the line pressure detection function with the cut-off valve operation confirmation. The same pressure detection unit serves dual purposes: monitoring line pressure and verifying cut-off valve operation, thereby reducing the need for separate detection systems and minimizing additional complexity while maintaining reliability
Solution Approach 2:
The pressure detection unit is designed to perform multiple functions: it detects line pressure for normal operation control and simultaneously confirms the operational status of the cut-off valve. This multi-functionality reduces the overall system complexity by eliminating the need for separate verification mechanisms
2Reliability
If hydraulic pressure is monitored by a hydraulic pressure sensor to perform operation confirmation, then operation confirmation reliability is improved, but device complexity and cost increase
Solution Approach 1:
The existing line pressure detection unit is utilized for dual purposes: normal line pressure monitoring and cut-off valve operation confirmation. This eliminates the need for dedicated hydraulic pressure sensors for verification, reducing device complexity while maintaining operation confirmation reliability
Solution Approach 2:
The system uses its own existing pressure detection capability to verify the operation of the cut-off valve. The line pressure detection unit essentially performs self-verification by detecting whether pressure is present or absent, confirming valve operation without requiring external or additional sensing components
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
The solution effectively detects line pressure and confirms the operation of the cut-off valve, preventing abnormal operations and maintaining essential functions even when the valve is stuck, thus ensuring reliable transmission performance while minimizing additional costs.
Implementation Method 1
a line pressure detection unit that detects a line pressure
Implementation Method 2
The cut-off valve has a valve element which is located at any one of a first position and a second position. The first position disables supply of a hydraulic fluid to the frictional engagement mechanism. The second position enables supply of the hydraulic fluid to the frictional engagement mechanism
Data Source
AI summary
A hydraulic control device for an automatic transmission includes a cut-off valve and a line pressure detector. The cut-off valve has a valve element located at one of a first position and a second position. The first position disables supply of a hydraulic fluid to a frictional engagement mechanism of the automatic transmission. The second position enables supply of the hydraulic fluid to the frictional engagement mechanism. The line pressure detector is configured to detect a line pressure. The cut-off valve is to control a hydraulic fluid passage so that the line pressure is supplied to the line pressure detector in a case where the valve element is at the first position and so that the line pressure is not supplied to the line pressure detector in a case where the valve element is at the second position.