Electromagnetic Clutch Control for Hysteresis Compensation
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Solution Overview
Problem
Existing driving force transmission devices in four-wheel-drive vehicles face accuracy issues due to magnetic hysteresis in the yoke and armature, causing variations in transmitted force even when current adjustments are made based on I-T characteristics.
Innovation Solution
A driving force transmission control apparatus that includes a storage unit for hysteresis values, a torque command calculator, a current command calculator, and a current control unit to perform feedback control, ensuring accurate current supply to the electromagnetic coil, accounting for differences in current requirements during increasing and decreasing energization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current is supplied to the electromagnetic coil based on I-T characteristics measured after assembly, then the driving force transmission is controlled, but the driving force accuracy deteriorates due to magnetic hysteresis causing variation between increasing and decreasing current states
Solution Approach 1:
The patent measures and stores hysteresis values during the assembly process before the device is put into service. These hysteresis characteristics are predetermined and stored in memory, allowing the control system to compensate for magnetic hysteresis effects during operation by using the pre-measured characteristics to calculate appropriate current values.
Solution Approach 2:
The patent implements a control mechanism that uses the stored hysteresis values to adjust the current supplied to the electromagnetic coil. The control unit calculates the required current by referencing the predetermined hysteresis characteristics, effectively compensating for the hysteresis effect and maintaining accurate driving force transmission.
2Ease of operation
If the same current is supplied to the electromagnetic coil, then the electromagnetic clutch mechanism operates, but the transmitted driving force varies due to magnetic hysteresis in the yoke and armature
Solution Approach 1:
The patent changes the control parameter from simple current magnitude to current magnitude adjusted by hysteresis compensation. By incorporating hysteresis values into the current calculation, the system accounts for the magnetic material's history-dependent behavior, ensuring that the same driving force is achieved regardless of whether the current is increasing or decreasing.
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 improves the accuracy of driving force transmission by reducing variations caused by magnetic hysteresis, ensuring consistent torque delivery and enhanced travel stability in four-wheel-drive vehicles.
Implementation Method 1
an electromagnetic clutch mechanism configured to attract an armature toward a yoke by a magnetic force generated by energization of an electromagnetic coil held by the yoke
Implementation Method 2
due to the magnetic hysteresis of the yoke and armature each made of a magnetic material, even when the same current is supplied to the electromagnetic coil, the driving force transmitted by the driving force transmission device varies depending on whether the current supplied is increasing or decreasing
Implementation Method 3
generate a frictional force between a plurality of clutch plates by moving the armature
Data Source
AI summary
A driving force transmission control apparatus includes: a driving force transmission device that includes an electromagnetic clutch mechanism configured to generate a frictional force between clutch plates by energization of an electromagnetic coil and transmits a driving force by actuating the electromagnetic clutch mechanism; and a control device that controls the driving force transmission device. The control device includes a storage unit storing a hysteresis value representing the difference between a current value required to transmit a predetermined torque when an energization current to the electromagnetic coil is gradually increased and a current value required to transmit the predetermined torque when the energization current is gradually reduced, a torque command value calculator that calculates a torque command value, and a current command value calculator that calculates a current command value representing a target value of a current to be supplied to the electromagnetic coil based on the torque command value and the hysteresis value.