Shift Control Hydraulic Circuit for Actuator Failure Evacuation
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Solution Overview
Problem
In shift-by-wire type shift control devices, malfunctions in electric actuators can prevent vehicles from being safely evacuated to a safe place due to the inability to switch hydraulic pressure supply paths.
Innovation Solution
A shift control device with a hydraulic circuit and multiple actuation valves that can switch positions or states in accordance with a shift position command, including a parking lock mechanism that restricts or permits axle rotation, and a control unit that manages these valves to ensure reliable vehicle evacuation, even in the event of actuator malfunctions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If a shift-by-wire type control device is used to control electric actuators, then the automation and convenience of shift control are improved, but the reliability of hydraulic pressure supply path switching deteriorates when electric actuators malfunction
Solution Approach 1:
A manual shift lever is introduced as an intermediary mechanism that can directly operate the hydraulic circuit independently of the electric actuator system. This manual operation path serves as a backup mediator when the electric shift-by-wire system fails, ensuring that hydraulic pressure can still be supplied to travel actuators for safe vehicle evacuation.
Solution Approach 2:
The system is designed with a manual shift lever that can be operated beforehand in case of electric actuator failure. This prior preparation allows the driver to manually switch hydraulic pressure supply paths when the automated system malfunctions, cushioning against the reliability deterioration caused by electric actuator failure.
2Reliability
If multiple actuation valves are added to the hydraulic circuit to ensure reliable operation, then the reliability of hydraulic pressure supply is improved, but the device complexity increases
Solution Approach 1:
The manual shift lever is designed to perform multiple functions: it serves as a normal shift control mechanism during regular operation and as a backup control mechanism when electric actuators fail. This multi-functionality allows the system to maintain reliability without adding completely separate redundant systems, thereby limiting the increase in device complexity.
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
Enables reliable vehicle evacuation to a safe place by ensuring hydraulic pressure supply path switching functionality, even when electric actuators malfunction, through the use of a hydraulic circuit with multiple actuation valves and a control unit that manages these valves to maintain essential vehicle operations.
Implementation Method 1
A hydraulic circuit 100a is provided with multiple actuation valves 110, 120, 106
Data Source
AI summary
A shift control device includes a hydraulic circuit and a control unit. The hydraulic circuit is provided with multiple actuation valves. The control unit is configured to switch positions or states of each of the multiple actuation valves in accordance with a shift position command by a shift operation device. The hydraulic circuit is configured to couples a hydraulic oil supply source to one of travel actuators in an automatic transmission in multiple circuit states where the position or the state of at least one of the multiple actuation valves differs.