Self-adjusting clutch actuator with positive locking transmission
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Solution Overview
Problem
Existing self-adjusting clutch actuators require high forces for reliable frictional engagement and precise component dimensions, making them complex and unreliable due to high precision requirements and potential failures in hydraulic systems.
Innovation Solution
A self-adjusting clutch actuator with a positive locking transmission mechanism that converts length adjusting movements into relative movements between components, achieving a gear ratio greater than 1, allowing for lower force engagement and increased reliability through frictional contact, using a lead screw and nut arrangement with a disc-shaped frustoconical locking body for efficient space use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a frictional engagement mechanism is used for locking, then the compensating mechanism can maintain locked state under adverse conditions, but high forces are required and precise component dimensions are needed
Solution Approach 1:
A positive locking transmission mechanism is introduced as an intermediary between the compensating mechanism components. This transmission includes a lead screw, nut, and disc-shaped frustoconical locking body that converts length adjusting movements into relative movements between components. The positive locking transmission mediates the force transmission and enables reliable locking with reduced force requirements compared to direct frictional engagement.
Solution Approach 2:
The patent changes the physical state and geometric parameters of the locking components. The disc-shaped frustoconical locking body with specific angle and dimensions transforms the engagement characteristics. By adjusting the cone angle and dimensional parameters of the locking surfaces, the mechanism achieves reliable locking with lower forces while maintaining precision under adverse conditions like oil entrainment.
2Reliability
If high precision component dimensions are used for reliable frictional engagement, then the locking is reliable, but the device complexity and manufacturing cost increase
Solution Approach 1:
The positive locking transmission acts as an intermediary mechanism that reduces sensitivity to component dimension variations. The lead screw and nut arrangement with frustoconical locking body provides mechanical advantage and self-centering effects, thereby reducing the criticality of manufacturing tolerances while maintaining reliable engagement.
Solution Approach 2:
The locking function is segmented into multiple independent components: the lead screw for movement conversion, the nut for mechanical advantage, and the disc-shaped frustoconical locking body for positive engagement. This segmentation allows each component to be manufactured with standard tolerances while achieving reliable overall performance, reducing device complexity.
3Manufacturing precision
If a positive locking transmission with gear ratio greater than 1 is used, then manufacturing tolerance criticality is reduced, but the device structure becomes more complex
Solution Approach 1:
The lead screw and nut arrangement serves multiple functions simultaneously: it converts axial movements to rotational movements, provides mechanical advantage through gear ratio greater than 1, enables self-centering of components, and facilitates the locking action. This multi-functionality reduces the need for additional separate mechanisms, thereby limiting the increase in device complexity.
Solution Approach 2:
The patent merges the movement conversion function, mechanical advantage function, and locking function into a single integrated positive locking transmission mechanism. The lead screw, nut, and frustoconical locking body work together as a unified system, combining multiple functions that would otherwise require separate components, thus limiting complexity increase.
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
The solution reduces the criticality of manufacturing tolerances and frictional engagement requirements, ensuring high-force transmission capability with a safety margin, maintaining locked state even under adverse conditions like oil entrainment, and allowing for length compensation after each actuation.
Implementation Method 1
using a lead screw and nut arrangement with a disc-shaped frustoconical locking body for efficient space use
Implementation Method 2
achieving a gear ratio greater than 1, allowing for lower force engagement and increased reliability through frictional contact
Data Source
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AI summary
The invention relates to a self-adjusting clutch actuator for operating a vehicle clutch of the type that is permanently biased to a fully engaged position, comprising a servo drive device (1), a piston (2) slidably mounted for linear movement in an axial direction, the piston being arranged to act on the vehicle clutch via a transfer member (8), the clutch actuator being arranged such that upon activation of the servo drive device (1) the piston (2) moves the transfer member (8) to move the vehicle clutch to its disengaged position, whereas upon deactivation of the servo drive the biased movement of the vehicle clutch back to its engaged position drives movement of the transfer member and thereby of the piston in the axial direction back to an end stop position thereof, wherein a compensating mechanism is disposed between piston (2) and transfer member (8) and is capable of changing between an unlocked state in which it is able to adjust its length to follow the axial position of the transfer member (8) in the engaged state of the vehicle clutch, and a locked state in which it is locked to a fixed length, characterized in that the compensating mechanism comprises a positive locking transmission (12, 14) which converts any length adjusting movement into a corresponding relative movement of a first and a second component of the compensating mechanism and vice versa, wherein the compensating mechanism is arranged such that its locked state is effected by moving the first and second components into frictional engagement with each other to thereby prevent length adjusting movements of the compensating mechanism by preventing said relative movement of the first and second components, wherein the transmission has a gear ratio of larger than 1.