Valve Actuation Using Dither to Reduce Hysteresis
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Solution Overview
Problem
Current cooling valve actuation systems in double-clutch transmissions face accuracy issues due to electromagnetic hysteresis and static friction, leading to potential transmission failures and discomfort for drivers.
Innovation Solution
A method for actuating a valve device using a characteristic curve with superimposed dither, where the frequency and amplitude of the dither are adjusted to flatten areas with high gradients, improving resolution and reducing the amplification of interfering influences, thereby increasing the accuracy of valve control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a pilot-operated distribution valve with electromagnetic pressure regulator is used for cooling control, then the adjustment range and regulation accuracy are improved, but electromagnetic hysteresis and static friction cause reduced actuation precision
Solution Approach 1:
The patent applies dither superimposition, which introduces high-frequency mechanical vibrations to the valve actuation system. This vibration prevents the valve components from settling into static friction states and reduces electromagnetic hysteresis effects, thereby improving actuation precision while maintaining control reliability
Solution Approach 2:
The patent implements periodic dither signals superimposed on the valve control signal. This periodic action continuously perturbs the valve actuation mechanism, preventing it from remaining stationary in positions where static friction would degrade precision, thus resolving the contradiction between precision and reliability
2Measurement precision
If dither with high frequency is applied to reduce hysteresis effects, then valve actuation accuracy is improved, but the system becomes more sensitive to interfering influences
Solution Approach 1:
The patent optimizes the dither frequency parameter to a specific range that balances two competing requirements: high enough to reduce hysteresis and friction effects, but not so high as to amplify the system's sensitivity to external interfering influences. This parameter optimization resolves the contradiction by finding the optimal operating point
3Speed
If the characteristic curve has high gradient areas for responsive control, then the system responds quickly to changes, but measurement and control accuracy deteriorates in these regions
Solution Approach 1:
In the high gradient regions of the characteristic curve where control accuracy would normally deteriorate, the patent applies dither superimposition to maintain precision. The vibration prevents the system from dwelling in sensitive regions where small signal variations would cause large output changes, thus maintaining both fast response and accuracy
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 approach enhances the accuracy of valve actuation, reducing the impact of hysteresis and friction effects, leading to improved cooling control and reduced wear on transmission components.
Implementation Method 1
a pilot pressure is set depending on an actuating current and an applied supply pressure, which in turn is applied to actuate the cooling valve
Implementation Method 2
the steady-state relationship is influenced by unit-specific tolerances in the area of the pilot stage or the electro-hydraulic pressure regulator, as well as geometric and mechanical tolerances of the electro-hydraulic transmission control system
Implementation Method 3
the steady-state relationship is influenced by unit-specific tolerances in the area of the pilot stage or the electro-hydraulic pressure regulator, as well as geometric and mechanical tolerances of the electro-hydraulic transmission control system
Data Source
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AI summary
The invention relates to a method for actuating a valve device on the basis of a characteristic curve (v_kk, v_kkD) via which a respective target value (i_EDS) that corresponds to an actuation variable of the valve device can be determined, said target value correlating to a characteristic curve (v_kk, v_kkD) starting value corresponding to a requested operating state of the valve device. The valve device is actuated using a dither which is superimposed with the target value (i_EDS) and which has such a frequency that the operating state of the valve device follows the actuation in a defined manner according to the characteristic curve (v_kk, v_kkD) and the characteristic curve (v_kk, v_kkD) is used to determine the respective starting values ("1", x) which correlate to the target values (i_EDS) present at the reversal points of the harmonic vibration imprinted onto the valve device by means of the dither and on the basis of which additional respective starting values are ascertained, wherein the actuation of the valve device is carried out on the basis of said additional starting values. The amplitude of the dither a specified such that during an actuation of the valve device, one of the reversal points lies in the vicinity of the transition region (i_EDS1, i_EDS2, i_EDS3, or i_EDS4) between a first characteristic curve region (v_kk1 or v_kk3) and a third characteristic curve region (v_kk2) or between a second characteristic curve region (v_kk3 or v_kk5) and a third characteristic curve region (v_kk4) in the first characteristic curve region (v_kk1 or v_kk3) or in the second characteristic curve region (v_kk3 or v_kk5) and the respective other reversal point lies in the third characteristic curve region (v_kk4).