Compound Linear Motion Rotary Actuator Friction Reduction
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Solution Overview
Problem
Conventional compound linear motion and rotary actuators face issues with frictional resistance from sealing portions, inadequate sealing capabilities, complex manufacturing processes, and insufficient lubrication due to the integration of spline shafts and pistons, which affect the longevity and functionality of the actuator.
Innovation Solution
A compound linear motion and rotary actuator design where an inside cylinder tube is concentrically provided within an outside cylinder tube, with a piston driven by pressurized fluid and a holder supported by a bearing for rotary motion, allowing the output shaft to move linearly without rotating, and eliminating the need for a sealing member fitting the spline's cross-section, thus separating the sealing functions and maintaining ambient air pressure for the rotary unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the spline shaft and piston are integrally formed to transmit rotation force, then the rotary motion can be transmitted to the output shaft, but frictional resistance increases due to the sealing portion rotating during linear motion
Solution Approach 1:
The patent divides the integral spline shaft-piston structure into separate components: a piston rod for linear motion and a spline shaft for rotary motion. The piston rod transmits only linear motion to the spline shaft, which then transmits rotary motion to the output shaft. This segmentation eliminates the rotation of the sealing portion during linear motion, reducing frictional resistance and energy loss.
2Device complexity
If the sealing portion serves both linear motion and rotary motion functions, then the structure is simplified, but sealing capability and lifespan are reduced
Solution Approach 1:
The patent separates the sealing functions into distinct sealing portions: a first sealing portion on the piston rod for linear motion sealing, and a second sealing portion on the spline shaft for rotary motion sealing. Each sealing portion is optimized for its specific motion type, improving sealing capability and lifespan while maintaining reasonable structural complexity.
Solution Approach 2:
The patent applies different sealing designs to different locations based on the specific motion requirements. The piston rod sealing is designed for linear reciprocating motion, while the spline shaft sealing is designed for rotary motion. This localized optimization ensures each sealing portion performs its function effectively without compromising the other.
3Device complexity
If the spline shaft penetrates the cylinder chamber, then the rotary drive can be integrated, but a specialized sealing member is required to prevent fluid escape
Solution Approach 1:
The patent separates the rotary drive components (spline shaft and holder) from the pressurized cylinder chamber. The spline shaft is positioned in the holder which is located in the atmosphere, not inside the pressurized chamber. This segmentation eliminates the need for complex specialized sealing members while maintaining integrated rotary drive functionality.
4Speed
If the piston rod with spline is moved in and out of the cylinder chamber, then linear motion is achieved, but lubrication of the sliding bearing becomes insufficient
Solution Approach 1:
The patent separates the high-speed linear motion function (performed by the piston rod in the cylinder chamber) from the rotary motion function (performed by the spline shaft in the holder). The sliding bearing on the piston rod only handles linear motion without rotary components, improving lubrication conditions and reliability while maintaining linear motion speed.
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 eliminates the need for a rotation drive mechanism to combat frictional resistance, ensures effective sealing, prolongs the actuator's lifespan, and stabilizes lubrication by keeping the rotary unit in an ambient air pressure environment, simplifying the construction and operation of the actuator.
Implementation Method 1
a piston which is driven by means of pressurized fluid is fit into a cylindrically shaped cylinder chamber
Implementation Method 2
a holder which is supported by means of a bearing in the inside cylinder tube and which is capable of being rotated
Data Source
AI summary
To eliminate necessity for rotating a rotation drive mechanism against frictional resistance originated by a sealing portion of a piston when an output shaft is rotated in a component linear motion and rotary actuator. An inside cylinder tube is concentrically provided in an outside cylinder tube and a piston that is driven by means of fluid pressure is fit into a cylinder chamber having a cylindrical shape formed between both the cylinder tubes in a manner so as to be slidable in an axial direction of the piston. A holder, which is rotatably supported by means of a bearing and which is capable of being rotated by means of rotation drive mechanism, is provided in the inside cylinder tube. An output shaft is inserted into the holder, in which the output shaft slides in the axial direction whereas the same does not rotate relative to the holder, and the output shaft is connected to the rod of the piston in a manner such that output shaft is rotatable by means of a bearing whereas the same integrally moves in the axial direction.