Linear Drive Nut Mechanism for Rattle-Free Wide Travel
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing linear drive device experiences rattling issues due to clearance between the lead screw and nut, limiting the movable range and increasing manufacturing costs with a complex structure and high component count, which complicates the suppression of rattling during motor operation.
Innovation Solution
A linear drive device design featuring a nut mechanism with a first nut portion not relatively movable and a second nut portion relatively movable, along with a spring biasing the second nut portion, to reduce rattling while maintaining a wide movable range, and utilizing a guide shaft and lead screw for stable load application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single nut mechanism is used to reduce rattling, then the structure becomes simpler, but the movable range is limited due to interference with the motor and surrounding members
Solution Approach 1:
The nut mechanism is segmented into a first nut portion and a second nut portion that are disposed at different positions in the axial direction of the lead screw. The first nut portion is configured to reduce rattling while the second nut portion is positioned to avoid interference with the motor and surrounding members, thereby maintaining a wide movable range. This segmentation allows each nut portion to perform its specific function independently without compromising the overall system performance.
2Reliability
If a spring is added to bias the nut portion to suppress rattling, then rattling is reduced, but the device complexity and component count increase
Solution Approach 1:
The spring is integrated into the nut mechanism assembly, where it is disposed between the first nut portion and the second nut portion. This merging approach allows the spring to bias the nut portions against the lead screw to suppress rattling while being part of the existing nut mechanism structure, rather than adding a separate, independent component. The spring's function is combined with the nut portions to achieve rattling suppression without significantly increasing device complexity.
3Length of moving object
If the nut portion is made relatively movable to avoid interference, then the movable range increases, but rattling occurs during motor operation
Solution Approach 1:
The first nut portion is configured with specific local qualities: it is disposed at a position where it can effectively contact the lead screw to suppress rattling, while the second nut portion is positioned at a different location to avoid interference with the motor and surrounding members. Each nut portion has optimized local characteristics that allow the system to achieve both wide movable range and effective rattling suppression simultaneously.
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 effectively suppresses rattling and widens the movable range by stabilizing the load application through the guide shaft and lead screw, reducing the complexity and cost of the structure while maintaining accurate positioning and reducing errors during motor operation.
Implementation Method 1
a first spring that biases the second nut portion in the axial direction
Data Source
AI summary
In a linear drive device, a movable member is driven using a guide shaft and a lead screw supported by a bracket. Since a nut mechanism, which with the lead screw configures a feed screw mechanism, is provided with a first spring between two nuts, it is possible to limit rattling of the nuts with respect to the lead screw. Of the two nuts, the first nut provided on the side opposite a motor and a first plate is not able to move relative to the movable member in the axis direction. As a result, when a member to be driven is loaded on the movable member and the movable member is driven in the direction approaching the first plate, the first plate and members disposed therearound are not susceptible to interference by the member being driven.