Actuator Reference Position via Stop Spring and Angle Sensor
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Solution Overview
Problem
Existing automated clutch systems in vehicles lack a reliable structural arrangement for determining a precise reference position, which can lead to inaccuracies in clutch actuation due to mechanical resistance and misalignment.
Innovation Solution
An actuator with a planetary roller screw drive incorporating a stop spring and angle sensor to determine the reference position of an axially movable component, where the stop spring is coupled to the ring gear and can be arranged between the spindle and the gear housing, allowing for precise torque measurement and angle detection to establish the equilibrium point.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a planetary roller screw drive is used to convert rotary motion to axial motion, then the actuation force and precision are improved, but the determination of the reference position becomes complex due to mechanical resistance and misalignment
Solution Approach 1:
A stop spring is introduced as an intermediary element between the planetary roller screw drive components. The stop spring makes contact at a specific equilibrium point during operation, providing a reliable mechanical reference position. This intermediary element simplifies reference determination by creating a distinct, detectable state (when the stop spring contacts the opposing component) without requiring complex sensor systems or multiple measurement points.
2Measurement precision
If incremental travel measurement sensors are used for clutch position feedback, then the control precision is improved, but the system requires regular calibration which increases maintenance time
Solution Approach 1:
The stop spring is pre-configured to contact the opposing component at a predetermined equilibrium point that corresponds to a specific clutch position. This preliminary mechanical reference is established during manufacturing, eliminating the need for field calibration. The system automatically references itself to this pre-established mechanical stop, allowing the incremental sensors to be used without periodic recalibration.
3Measurement precision
If a stop spring is introduced to establish a reference position, then the reference accuracy is improved, but the device complexity increases due to additional components
Solution Approach 1:
The stop spring serves multiple functions simultaneously: it provides the mechanical reference position for the planetary roller screw drive, acts as a mechanical stop to prevent over-travel, and creates a detectable equilibrium point for the angle sensor. By combining these functions into a single element, the reference accuracy is improved without proportionally increasing device complexity.
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 provides a reliable method for determining the reference position, minimizing mechanical load and inertial forces, and allowing for easier adjustment of preload forces, thereby enhancing the accuracy and reliability of clutch actuation in vehicle systems.
Implementation Method 1
the means for determining the reference position of the axially movable component further contain a stop spring and an angle sensor for determining a change in the angle of the spindle
Implementation Method 2
several planetary rollers being engaged with a spindle, which mesh with a ring gear surrounding the planetary rollers
Implementation Method 3
a planetary roller screw drive (PWG), with a threaded spindle and with a nut arranged on the threaded spindle, and with several planets distributed over the circumference, arranged between the threaded spindle and the nut, which are arranged to be able to roll on the inner circumference of the nut and on the outer circumference of the threaded spindle
Data Source
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AI summary
The invention relates to an actuator with a planetary rolling threaded spindle drive (PWG), in particular for activating a clutch of a vehicle by means of an axially movable piston, wherein a plurality of planetary rollers engage with a spindle and mesh with a ring gear surrounding the plantary rollers, wherein the planetary rollers run axis-parallel with respect to the spindle, and are positioned in a planetary roller carrier so as to be rotatable about their own longitudinal axis, and wherein the actuator has at least one axially movable component for implementing a disengagement movement, which component is either the spindle or the transmission housing, and wherein means for determining a reference position of the axially movable component are integrated, and wherein, furthermore, the means for determining the reference position of the axially movable component contain a stop spring and an angle sensor for determining a change in angle of the spindle.