Clutch Actuator Sensing for Precise Release and Pushrod Load Relief
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Solution Overview
Problem
Existing clutch actuators for motor vehicles face challenges in achieving precise actuation while simultaneously allowing for wear adjustment and load relief on the pushrod in the coupled mode, leading to increased wear due to vibration transfer.
Innovation Solution
Incorporation of a stroke sensor associated with the guide component and a rotation angle sensor with a controller to determine the start of the release stroke, enabling precise zero point determination and decoupling of the tappet from the pushrod, using Hall-effect or GMR sensors for high accuracy detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the pushrod is kept in contact with the tappet for precise actuation, then actuation precision is improved, but vibration is transferred to the pushrod causing increased wear
Solution Approach 1:
The system dynamically adjusts the coupling state between pushrod and tappet based on operational phase. During actuation, the pushrod maintains contact for precision; during idle/coupled state, the pushrod is decoupled (retracted 1-4mm) to eliminate vibration transfer, with sensors and control logic managing the transition between these states
2Reliability
If the pushrod is retracted further for load relief, then vibration transfer is reduced, but actuation precision deteriorates
Solution Approach 1:
The system performs preliminary positioning of the pushrod to the exact decoupling point (1-4mm retraction) before the coupled state is reached. The stroke sensor detects when the tappet reaches its forward limit, and the control logic commands the pushrod to retract to the precise load-relief position, ensuring both wear protection and subsequent actuation precision
3Adaptability or versatility
If wear adjustment range is increased to 90mm, then adaptability is improved, but device complexity increases
Solution Approach 1:
The patent replaces complex mechanical wear adjustment mechanisms with an electric motor-driven system. The motor rotates the pushrod via a spindle mechanism, and electronic sensors (stroke sensor, rotation angle sensor) with a control unit manage the 90mm adjustment range, simplifying the mechanical structure while enabling precise, programmable wear compensation
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 allows for precise clutch actuation and load relief, reducing long-term wear by accurately detecting movements and adjusting the zero point, thereby minimizing vibration transfer and wear.
Implementation Method 1
the guide component is provided with a permanent magnet, thus enabling the stroke of the guide component and hence of the tappet to be detected very precisely by means of the stroke sensor
Implementation Method 2
As sensors, it is possible, in particular, to use Hall-effect sensors or GMR sensors, which make it possible to detect the desired movement with a very high accuracy
Data Source
AI summary
A clutch actuator for actuating a clutch in the drive train of a motor vehicle, having a housing, a drive, a pushrod, which can be adjusted in an axial direction by the drive, a tappet, which is coupled to the pushrod, and a guide component which is accommodated movably in the housing and receives that end of the tappet which faces the pushrod. At least one stroke sensor, which is associated with the guide component, and a rotation angle sensor, which is associated with the drive, are provided. Embodiments relate to an assembly having a clutch actuator of this kind and a controller, the controller is set up and designed to determine the start of the release stroke of a clutch actuated by the clutch actuator from a comparison of the signal of the stroke sensor and the signal of the rotation angle sensor.