Switching Valve Hydraulic Control for Automatic Transmission Tie-Up Prevention
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Solution Overview
Problem
Conventional hydraulic control apparatuses for automatic transmissions face tie-up issues due to failed solenoid valves, leading to shifts that impair driveability, such as drastic downshifts, when a solenoid valve remains engaged, causing additional hydraulic frictional engagement devices to be locked, which affects gear mechanisms.
Innovation Solution
A hydraulic control apparatus with a switching valve device that includes a first output port, a first input port, and a first drain port, allowing communication between these ports to disengage the faulty solenoid valve and achieve a specific shift speed, thereby preventing tie-up without requiring engagement of the faulty solenoid valve's corresponding hydraulic frictional engagement device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the shift speed is changed to another shift speed that is achieved on the condition that the hydraulic frictional engagement device corresponding to the failed solenoid valve is engaged, then tie-up is prevented, but a shift that may impair driveability may be executed
Solution Approach 1:
A switching valve device is introduced as an intermediary component between the solenoid valve and the hydraulic frictional engagement device. This switching valve includes a first output port connected to the solenoid valve, a first input port receiving original pressure, and a first drain port. When a failure is detected, the switching valve redirects hydraulic pressure from the first output port to the first drain port instead of allowing it to reach the solenoid valve, thereby preventing the faulty engagement device from being activated while maintaining normal operation of other components.
Solution Approach 2:
The hydraulic control system is segmented into separate controllable pathways. The switching valve creates distinct hydraulic circuits: one pathway (first output port to first input port) for normal operation and another pathway (first output port to first drain port) for failure conditions. This segmentation allows independent control of the faulty engagement device while preserving the functionality of other engagement devices, enabling tie-up prevention without drastic shift changes.
2Reliability
If a given solenoid valve remains in the position to output the hydraulic pressure due to a failure, then the hydraulic frictional engagement device is constantly maintained in the engaged state, but the gear mechanisms may be locked causing tie-up
Solution Approach 1:
The switching valve device is pre-configured with failure detection and response capabilities before actual failures occur. The valve includes predetermined pathways (first input port, first output port, first drain port) and control logic that automatically activates when a solenoid valve failure is detected. This preliminary setup enables immediate response to failures without requiring complex real-time analysis or manual intervention, simplifying the overall control system while maintaining high reliability.
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 configuration allows for the prevention of shifts that impair driveability by disengaging the faulty hydraulic frictional engagement device and maintaining a specific shift speed, reducing the likelihood of drastic downshifts and ensuring smoother vehicle operation.
Implementation Method 1
a first output port, a first input port, and a first drain port. The first output port is connected to an input port of a solenoid valve among the plurality of solenoid valves... When there is a failure that may cause tie-up, communication is provided between the first output port and the first drain port
Data Source
AI summary
In a hydraulic control apparatus for a vehicular automatic transmission, if it is determined that there is a failure that may cause tie-up in an automatic transmission, communication is provided between a first output port and a first drain port in a switching valve. As a result, a hydraulic frictional engagement device, which should be disengaged when there is a failure, is disengaged. Also, a specific shift speed is achieved by controlling the switching valve. Therefore, it is not necessary to select a shift speed that is achieved on the condition that the hydraulic frictional engagement device, which should be disengaged when there is a failure, is engaged. Thus, it is possible to prevent a shift that may impair driveability when there is a failure that may cause tie-up in the automatic transmission.