Electric Actuator Screw Shaft Support Mechanism
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Solution Overview
Problem
Conventional electric actuators face issues with vibration and off-centering of the feed screw shaft due to inadequate support, leading to reduced precision and increased manufacturing complexity, especially when the screw shaft length varies with stroke length.
Innovation Solution
The electric actuator incorporates a support mechanism for the screw shaft in the radial direction, utilizing a connecting member and a rotation regulating mechanism to prevent rotational displacement, ensuring precise axial displacement and reducing manufacturing complications by eliminating the need for multiple screw shaft lengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the feed screw shaft is supported at only one location by a bearing, then the structure is simple, but the screw shaft becomes inclined and off-centered at high speeds, generating vibrations
Solution Approach 1:
The support structure is segmented into multiple bearing locations along the screw shaft. Instead of a single bearing, the patent employs bearings at both ends of the screw shaft, dividing the support function into separate segments that collectively provide stable support throughout the shaft's length, preventing off-centering and vibrations.
2Manufacturing precision
If the feed screw shaft length is varied to match different stroke amounts, then the actuator performance is optimized, but manufacturing complexity increases and productivity decreases
Solution Approach 1:
The screw shaft is designed with universal support at both ends that can accommodate various stroke lengths. The bearing support structure is configured to work effectively regardless of the specific screw shaft length, allowing a single standardized support design to serve multiple applications with different stroke requirements, thereby simplifying manufacturing while maintaining performance.
Solution Approach 2:
The patent changes the support configuration from a single-point bearing to a two-point bearing arrangement. This parameter change in the support structure allows the system to maintain stability across varying screw shaft lengths without requiring different support designs for each stroke amount, enabling standardized manufacturing processes.
3Device complexity
If the nut is allowed to move freely along the screw shaft, then the displacement mechanism is simple, but the nut may rotate together with the screw shaft, reducing precision
Solution Approach 1:
A groove structure is introduced as an intermediary element between the nut and screw shaft. The groove in the screw shaft engages with a corresponding protrusion on the nut, acting as a mediator that prevents rotational movement of the nut while allowing smooth axial displacement. This intermediary feature adds minimal complexity while significantly improving displacement precision.
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 design enhances precision and productivity by preventing off-centering and vibration, allowing for smooth and precise displacement of the displacement member even at high speeds, while simplifying manufacturing by eliminating the need for varied screw shaft lengths.
Implementation Method 1
a screw shaft (58), which is rotatably displaced by the drive force transmitted through the drive force transmission mechanism (22)
Implementation Method 2
a bearing (32, 72), which supports the screw shaft (58) in a radial direction
Implementation Method 3
a rotation regulating mechanism (50), which is disposed on an outer circumferential surface of the displacement member (48, 18), and is engaged in a groove (46) of the body (12)
Data Source
AI summary
In an electric actuator, a connector is coupled to one end of a screw shaft that makes up a displacement mechanism, the screw shaft being rotatably supported by first and second bearings. Further, on the other end of the screw shaft, a support ring is disposed through a holder, wherein the support ring is slidable along an inner circumferential surface of a piston rod. On the outer circumferential surface of a piston, a rotation-stopping member is provided, which includes projections thereon that project in a radial direction from the outer circumferential surface, the projections being inserted into grooves of said body.