Synchronous Meshing Pressure Control for Low-Temperature Engagement
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Solution Overview
Problem
The synchronous meshing mechanism in vehicles experiences increased resistance force due to drag torque at low hydraulic oil temperatures, leading to potential sleeve failure and collision noise issues during engagement transitions, as the thrust force required to overcome this resistance is not sufficient.
Innovation Solution
A control apparatus with an electronic control unit that adjusts the command pressure for the hydraulic actuator to an intermediate pressure after synchronization, reducing thrust force and collision noise, and switches to meshing completion pressure if the sleeve fails to move, ensuring engagement completion despite low oil temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the thrust force of the sleeve is reduced to lower collision noise, then collision noise is reduced, but the sleeve cannot overcome the resistance force at low temperatures
Solution Approach 1:
The control apparatus dynamically adjusts the command pressure for the hydraulic actuator based on real-time monitoring of sleeve position and engagement status. The system transitions between different pressure levels (intermediate pressure for noise reduction, meshing completion pressure for reliable engagement) rather than using a fixed pressure value, allowing optimal performance across varying temperature conditions.
Solution Approach 2:
The system implements a feedback mechanism where the electronic control unit continuously monitors whether the spline teeth are meshed and adjusts the command pressure accordingly. When synchronization is detected, the system switches to intermediate pressure to reduce noise; when meshing is not achieved within a predetermined time, it switches to meshing completion pressure to ensure engagement, creating a closed-loop control system that adapts to actual engagement status.
2Object-generated harmful factors
If the command pressure is set to intermediate pressure after synchronization, then collision noise is reduced, but engagement may not be completed at low temperatures
Solution Approach 1:
The control system employs periodic action by implementing a time-based monitoring mechanism. After switching to intermediate pressure upon detecting synchronization, the system waits for a predetermined time period to elapse. If engagement is not completed within this period, the system switches to meshing completion pressure, creating a staged, periodic approach to engagement that balances noise reduction with reliable completion.
Solution Approach 2:
The command pressure is dynamically adjusted based on the elapsed time since synchronization detection and the actual engagement status. The system transitions from intermediate pressure (for noise reduction) to meshing completion pressure (for ensuring engagement) based on real-time conditions, making the pressure profile adaptive rather than static.
3Reliability
If the command pressure is set to meshing completion pressure continuously, then engagement is ensured, but collision noise increases
Solution Approach 1:
The engagement process is segmented into distinct phases with different pressure requirements. The control system divides the engagement sequence into: (1) synchronization phase with high pressure, (2) post-synchronization phase with intermediate pressure for noise reduction, and (3) fallback phase with meshing completion pressure if engagement is not achieved. This segmentation allows optimal pressure selection for each phase, reducing overall collision noise while ensuring engagement completion.
Solution Approach 2:
The system applies partial action by using intermediate pressure (less than meshing completion pressure) during the post-synchronization phase when the sleeve is already moving toward engagement. This reduced pressure is sufficient to complete engagement under normal conditions while minimizing collision noise, applying full meshing completion pressure only when necessary (after predetermined time elapses without meshing).
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 solution effectively reduces collision noise and prevents sleeve failure by dynamically adjusting pressure settings based on oil temperature, ensuring reliable engagement of the synchronous meshing mechanism even at low temperatures.
Implementation Method 1
a hydraulic actuator that applies a thrust force to the sleeve and moves the sleeve in the axial direction of the rotary shaft
Implementation Method 2
a synchronizer ring that is interposed between the gear and the sleeve
Data Source
AI summary
A control apparatus for a synchronous meshing mechanism that is equipped with a gear, a sleeve, a synchronizer ring, and a hydraulic actuator is provided. When it is determined that the sleeve and the gear have been rotationally synchronized with each other in an engagement transition period of the synchronous meshing mechanism, an electronic control unit with which the control apparatus is equipped sets a command pressure for the hydraulic actuator to an intermediate pressure that is lower than a meshing completion pressure. Besides, when meshing has not been completed even after the lapse of a predetermined time from a timing when the command pressure for the hydraulic actuator is set to the intermediate pressure, the electronic control unit sets the command pressure for the hydraulic actuator to the meshing completion pressure.