Actuator Anti-Backlash Transmission Using Cam-Controlled Torque
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Solution Overview
Problem
Backlash occurs in transmission systems due to clearances and tolerances between components, leading to control issues with the motion and position of targets in actuators.
Innovation Solution
The implementation of an anti-backlash mechanism in actuators, which includes an extended section such as a cam or gear segment, coupled with a spring and cam follower or pinion gear, to provide a controllable torque over a target range of angles, thereby eliminating play at interfaces and maintaining controlled contact between surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If clearance and tolerance are reduced between transmission components, then backlash is reduced, but manufacturing complexity and cost increase
Solution Approach 1:
A cam mechanism is introduced as an intermediary element between the drive screw and the output components. The cam surface profile is specifically designed to compensate for clearances and tolerances in the transmission path, maintaining consistent contact and eliminating backlash without requiring tighter manufacturing tolerances on the standard transmission components.
Solution Approach 2:
The cam surface geometry is designed with specific curvature and profile parameters that change throughout the rotation cycle. These parameter variations in the cam surface allow for dynamic compensation of transmission clearances, providing backlash elimination through geometric design rather than through reduced component tolerances.
2Reliability
If a rigid connection is used between transmission components, then backlash is eliminated, but the system cannot accommodate tolerance variations
Solution Approach 1:
The cam mechanism provides a dynamic connection that adapts to tolerance variations. As the cam rotates, its surface profile continuously adjusts the contact position and force distribution, maintaining rigid effective connection for backlash elimination while accommodating dimensional variations in the connected components through its geometric compliance.
Solution Approach 2:
The cam surface is pre-designed with a profile that anticipates and counteracts the effects of clearance and tolerance. The geometry is configured to apply corrective forces and maintain proper alignment before backlash can manifest, preventing the harmful effects of clearances rather than reacting to them.
3Ease of manufacture
If standard transmission components are used, then ease of manufacture is maintained, but backlash control precision is insufficient
Solution Approach 1:
The backlash control function is segmented from the standard transmission components and embodied in the separate cam mechanism. This allows the use of conventional, easily manufactured transmission components (drive screw, nut, gears) while the specialized precision function is isolated to the cam surface, which can be manufactured and adjusted independently.
Solution Approach 2:
The cam acts as an intermediary that bridges the gap between standard components with inherent clearances and the requirement for precise backlash control. It mediates the interaction between components, providing the necessary precision through its surface geometry while allowing the standard components to maintain their easier-to-manufacture tolerances.
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 anti-backlash mechanism effectively reduces backlash in transmission systems, allowing for precise control of torque and motion over a defined range, enhancing the accuracy and reliability of actuator performance.
Implementation Method 1
The load may comprise a cam follower and a spring. One end of the spring is anchored and the other end is connected to the cam follower. The cam follower contacts the cam surface and exerts a force on the cam surface.
Implementation Method 2
The extended section may comprise a cam. The load may comprise a cam follower and a spring. The cam follower contacts the cam surface and exerts a force on the cam surface. This causes a controllable torque when the at least one of the plurality of components or the output shaft rotates and the cam follower contacts different portions of the cam surface.
Implementation Method 3
The extended section may comprise a gear segment. The load may comprise a spring, a pinion gear lever and a pinion gear. The pinion gear is connected to the pinion gear lever, where the pinion gear meshes with the gear segment and exerts a force on the gear segment, causing the controllable torque.
Data Source
AI summary
Apparatuses and techniques for reducing backlash between components in a transmission system are provided. The apparatuses and techniques provide a controllable torque over a target range of motion of a component in the transmission system. This eliminates the play at the interfaces between components and forces the components to maintain a controlled contact between the interfacing surfaces.