Hydraulic Multi-Plate Clutch VKP Setting for Precise Shift Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing control systems for hydraulic multi-plate clutches in vehicle transmissions face challenges in accurately setting the volumetric kiss point (VKP), leading to nonlinear relationships between control current and hydraulic pressure, which affects the precision of clutch engagement and disengagement.
Innovation Solution
A method involving a controller that generates a current-hydraulic model, sets a temporary VKP based on the maximum difference between the model and measured hydraulic pressure, and iteratively refines this value by adjusting pressures and observing pressure drops to determine a stable VKP, ultimately setting a final VKP for precise clutch control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the control current is increased to achieve desired hydraulic pressure, then the clutch engagement force is improved, but nonlinear pressure changes occur due to piston movement and spring compression
Solution Approach 1:
The system performs preliminary identification of the VKP point before normal operation. By pre-determining the volumetric kiss point where the piston stops moving and spring compression ends, the controller can switch control strategies at this critical threshold, maintaining linearity by adjusting solenoid valve control after the VKP is reached.
Solution Approach 2:
The controller dynamically changes control parameters based on the operating phase. Before VKP, it uses one control strategy; after VKP, it switches to a different strategy that accounts for the completed piston movement, thereby maintaining the linear relationship between control current and hydraulic pressure across different operating conditions.
2Measurement precision
If the solenoid valve is controlled to achieve precise hydraulic pressure, then clutch control precision is improved, but sticking phenomena occur causing pressure drops
Solution Approach 1:
The system implements feedback control by monitoring hydraulic pressure and comparing it with the identified VKP point. When pressure deviations or sticking phenomena are detected, the controller adjusts the solenoid valve control accordingly, using the feedback information to maintain stable pressure and prevent sticking.
Solution Approach 2:
The VKP point is identified in advance through a dedicated identification routine before normal clutch operation. This preliminary characterization of the system's nonlinear behavior allows the controller to compensate for sticking phenomena by adjusting control signals based on the known VKP characteristics.
3Measurement precision
If the control system accounts for nonlinear sections, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The control process is segmented into distinct phases: VKP identification phase and normal operation phase. By dividing the control strategy into these segments, the system handles nonlinear behavior in a structured way, applying different control algorithms appropriate to each phase rather than attempting a single complex solution.
Solution Approach 2:
The system performs self-characterization by automatically identifying its own VKP point through controlled operation and observation of pressure-current relationships. This self-service approach eliminates the need for manual calibration or complex external measurement equipment, reducing overall system complexity while maintaining precision.
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 method improves the accuracy of clutch control and enhances transmission quality by ensuring precise engagement and disengagement, reducing the influence of nonlinear pressure changes and sticking phenomena.
Implementation Method 1
a solenoid valve (510) electrically connected to the controller (508) and fluidically connected to the clutch (500)
Implementation Method 2
a piston (504) which is moved by hydraulic pressure pressurizes the overlapped clutch plates (500) and clutch disks (502)
Implementation Method 3
the elastic force of a spring (506) causes the piston (504) to return to the original position thereof
Implementation Method 4
a substantial frictional force starts to be generated between the clutch plate (500) and the clutch disk (502)
Data Source
AI summary
A method of setting a clutch control reference value may make it possible to more accurately learn the VKP of a hydraulic multi-plate clutch controlled by a solenoid valve, improving the accuracy of clutch control, and furthermore, to improve the quality of shifting a vehicle by the precise control of a transmission provided with such a clutch.