Clutch Actuator Positioning Using Coil Resistance Temperature Sensing
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Solution Overview
Problem
In vehicle drive trains with form-fitting clutches, temperature-dependent viscosity of transmission fluid complicates accurate determination of piston position, leading to delayed torque transmission and increased costs due to the need for additional sensors and complex temperature modeling.
Innovation Solution
The method employs the electromagnetic actuator's coil as a temperature sensor, using electrical resistance changes to determine transmission fluid temperature and viscosity, allowing for accurate piston position determination and faster clutch engagement without additional sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a temperature sensor is installed in the transmission housing to determine transmission fluid temperature, then the accuracy of piston position determination is improved, but the device complexity and installation costs increase
Solution Approach 1:
The electromagnetic actuator's coil is made to serve dual functions: actuating the clutch and sensing transmission fluid temperature. By measuring the coil's electrical resistance, which varies with temperature, the system eliminates the need for a separate temperature sensor while maintaining measurement accuracy
Solution Approach 2:
The electromagnetic actuator performs self-diagnosis by using its own coil's electrical properties to determine transmission fluid temperature. This self-service approach allows the actuator to compensate for temperature-dependent viscosity effects without external sensing components
2Measurement precision
If additional temperature sensors and complex temperature modeling are implemented, then the accuracy of clutch engagement determination is improved, but the manufacturing costs and installation space increase
Solution Approach 1:
The electromagnetic actuator's coil is made to serve dual functions: actuating the clutch and sensing transmission fluid temperature. By measuring the coil's electrical resistance, which varies with temperature, the system eliminates the need for a separate temperature sensor while maintaining measurement accuracy
Solution Approach 2:
Instead of implementing expensive temperature sensors and complex modeling systems, the invention uses the existing electromagnetic coil's electrical resistance property, which is already present in the actuator. This approach uses readily available components to achieve temperature sensing without additional cost
3Device complexity
If the piston position is determined without temperature compensation, then the device complexity is reduced, but the accuracy of clutch engagement timing deteriorates
Solution Approach 1:
The electromagnetic actuator performs self-diagnosis by using its own coil's electrical properties to determine transmission fluid temperature. This self-service approach allows the actuator to compensate for temperature-dependent viscosity effects without external sensing components
Solution Approach 2:
The system uses real-time measurement of the electromagnetic coil's electrical resistance to obtain feedback on transmission fluid temperature. This feedback is then used to compensate for viscosity changes and accurately determine piston position and clutch engagement timing
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 enables quicker and more accurate determination of clutch engagement, reducing the time required for torque transmission and eliminating the need for additional sensors, thus saving costs and installation space.
Implementation Method 1
employing the actuator's coil as a temperature sensor, using electrical resistance changes to determine transmission fluid temperature and viscosity
Implementation Method 2
The actuating unit includes an electromagnetic actuator having a piston, the piston being moved from a starting position into an end position in order to actuate the clutch
Implementation Method 3
The transmission fluid has a temperature-dependent viscosity; the movement of the piston and/or the displacement of the clutch components may be influenced by the viscosity
Implementation Method 4
The clutch includes at least a first clutch component and a second clutch component that are connected to one another in a form-fitting manner when the clutch is actuated
Data Source
AI summary
A vehicle drive train, has a clutch unit actuatable by an actuating unit, and a sensor for determining the coupling status. The actuating unit includes an electromagnetic actuator having a piston movable from a starting to an end position. At least the piston and the clutch are acted on by a transmission fluid. Operating the drive train can include:a) actuating the actuator and moving the piston from the starting position;b) ascertaining a measured sensor value;c) ascertaining a temperature of the transmission fluid by measuring an electrical resistance of the actuator and/or measuring a first time interval between actuation of the actuator according to step a) and the detection by the sensor of an intermediate position that is reached by the piston;d) determining an actual position of the piston based on the measured sensor value and the temperature; ande) moving the piston, starting from the determined actual position, into the end position.