Locking Member Bearing Face Geometry for Coupler Retention
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Solution Overview
Problem
Quick coupler assemblies for public works machines face safety issues due to reduced friction between the locking member and connection device, particularly when lubricating agents are present, leading to potential tool disconnection and accidents.
Innovation Solution
The design incorporates an additional portion on the bearing face of the locking member with a specific shape that extends from the main portion, providing increased contact surface and a moment to counteract disconnection forces, ensuring the locking member remains engaged even under reduced friction conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the bearing face of the locking member has a convex shape with increasing engagement radius, then play between the coupler and connecting device is compensated, but friction is reduced when lubricant is present, leading to potential tool disconnection
Solution Approach 1:
The bearing face is segmented into two distinct portions: a main portion with a first convex shape that compensates for play, and an additional portion with a second convex shape that provides enhanced friction and mechanical interlocking. This segmentation allows each portion to perform its specific function independently, resolving the contradiction between play compensation and reliable retention.
Solution Approach 2:
Different portions of the bearing face are given different local qualities: the main portion has a larger radius of curvature optimized for play compensation, while the additional portion has a smaller radius of curvature optimized for maintaining friction and preventing disconnection. This local differentiation allows the bearing face to simultaneously address both requirements.
2Duration of action of moving object
If the bearing face is designed to compensate for wear and play, then the engagement radius increases from rear to front, but the friction force becomes insufficient under lubricated conditions
Solution Approach 1:
The bearing face is divided into a main portion for wear compensation and an additional portion for maintaining friction force. The additional portion's smaller radius of curvature creates higher contact pressure and friction, ensuring sufficient holding force even when the main portion experiences wear and play.
Solution Approach 2:
The two portions of the bearing face have asymmetric geometries with different radii of curvature. The additional portion's smaller radius creates a more aggressive contact profile that generates higher friction forces, compensating for the reduced friction in the main portion due to lubrication.
3Stability of the object's composition
If the locking member pivots towards the engaged position, then the engagement radius increases to compensate for play, but the moment created by normal force tends to rotate the locking member towards the disengaged position
Solution Approach 1:
The bearing face is segmented so that the additional portion creates a stabilizing moment that counteracts the destabilizing moment from the main portion. This segmentation allows the locking member to remain stably engaged despite the geometric tendency towards disengagement.
Solution Approach 2:
The additional portion of the bearing face acts as a counterweight to the destabilizing moment created by the main portion. By providing an opposing moment through its smaller radius of curvature, it balances the forces and maintains the locking member in the engaged position.
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 configuration enhances the safety and reliability of the connection by maintaining tool retention under normal and adverse conditions, such as the presence of lubricants, without compromising the locking member's ability to pivot between engaged and disengaged positions.
Implementation Method 1
The tangential component of this force, corresponding to friction between the bearing surface of the locking device and the functional face of the connecting device, prevents this rotation and ensures the equilibrium that retains the tool on the machine arm.
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The locking member (13), which is mounted on a coupler (5), can pivot about a transverse axis (23) between a disengaged position and an engaged position in which its bearing face (18) cooperates with a functional face (20) of a connecting device (4) fixed to a tool, to ensure the tool is retained on the arm of a machine. The bearing face has a convex main portion (30) allowing for play compensation during normal operation, and an additional portion (40) extending rearward from the main portion. The geometry of the additional portion (40) is designed to create an equilibrium position, then force the locking member to pivot toward its engaged position, in order to prevent the tool from disconnecting under the working forces exerted by the tool.