Automatic Transmission Control for Pseudo D State Detection
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Solution Overview
Problem
Automatic transmissions experience a 'pseudo D' state where the manual valve is not at the traveling range position, leading to a mismatch between hydraulic pressure instruction and actual pressure, causing premature engagement and shock to the driver, and existing solutions require operation of the select lever to resolve, delaying smooth vehicle start.
Innovation Solution
A control apparatus and method that includes an operating unit, detecting unit, valve, and hydraulic pressure controller to detect the traveling range and determine if the friction elements are not engaged, distinguishing between pseudo D state and hydraulic pressure controller failure, allowing early detection and prevention of delay in engagement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the hydraulic pressure controller supplies hydraulic pressure to friction elements when traveling range is detected, then the friction elements engage rapidly, but this causes evil shock to the driver when the manual valve is not at the traveling range position (pseudo D state)
Solution Approach 1:
The system performs preliminary detection of the manual valve position using the manual valve position detection means before executing hydraulic pressure control. This preliminary action identifies the pseudo D state in advance, preventing the harmful rapid engagement shock from occurring while still allowing quick engagement when the system is in a normal state.
2Reliability
If the system waits for select lever operation to resolve pseudo D state, then the cause can be identified, but this results in a long determination period that interferes with smooth vehicle start
Solution Approach 1:
The system uses feedback from the manual valve position detection means to continuously monitor whether the manual valve is at the correct traveling range position. This real-time feedback allows the system to immediately identify the pseudo D state without waiting for select lever operation, enabling quick determination while maintaining accurate cause detection.
Solution Approach 2:
The system replaces the mechanical waiting-for-lever-operation approach with an electronic detection system that uses sensors and control units to automatically detect the manual valve position. This substitution eliminates the need for manual intervention and significantly reduces the determination period while maintaining reliable cause identification.
3Reliability
If the system detects hydraulic pressure controller failure by monitoring friction element engagement, then the failure can be identified, but this requires a long determination period that delays smooth vehicle start
Solution Approach 1:
The system performs preliminary detection of the manual valve position before initiating hydraulic pressure control. This preliminary action ensures that failure detection is only attempted when the system is in a normal state, allowing for immediate and accurate failure identification without extending the overall determination period.
Data Source
AI summary
A control apparatus includes a select lever, an inhibitor switch, a manual valve, a first SOL, a second SOL, and a controller. The controller controls the first SOL and the second SOL such that a hydraulic pressure is supplied to a first friction element and a second friction element when the inhibitor switch detects a D range. The controller determines that an operation position is at an intermediate position when operations of the first friction element and the second friction element are not detected. The controller determines that the first SOL has a failure when the operation of the first friction element is not detected.