Single-Bushing Pneumatic Actuator for Stable Compact Shaft Support
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Solution Overview
Problem
Conventional slotted crank pneumatic actuators require two bushings for support, leading to increased size and weight, and potential shaft tilting due to frictional forces, which limits their ability to fit within smaller envelopes and reduces efficiency.
Innovation Solution
A pneumatic actuator design utilizing a single bushing with a length-to-diameter ratio greater than 1, positioned centrally to support the actuator shaft, allowing motion while constraining actuator force within operational limits, and eliminating the need for an intermediate link, thereby reducing size and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two bushings are used to support the actuator shaft, then the shaft is more stable and supported at multiple locations, but the actuator size and weight increase
Solution Approach 1:
The patent removes one of the two traditional bushings, retaining only a single bushing at one end of the actuator shaft. This extraction of the redundant support element reduces the actuator weight and component count while the remaining single bushing is designed with optimized dimensions (length-to-diameter ratio between 2-3) to provide sufficient support stability for the application.
2Reliability
If two bushings are used to support the actuator shaft, then the shaft is supported at multiple locations, but the overall actuator envelope size increases
Solution Approach 1:
By eliminating the second bushing and its associated mounting structure, the actuator's overall envelope area is reduced. The single bushing configuration allows for a more compact actuator design that can fit within smaller spatial constraints while maintaining adequate shaft support through proper bushing dimensioning.
Solution Approach 2:
The function of supporting the actuator shaft is consolidated into a single bushing element rather than being distributed across two separate support points. This merging of support function into one location reduces the spatial footprint while the bushing's optimized length-to-diameter ratio ensures it provides sufficient structural support.
3Weight of stationary object
If a single bushing is used to support the actuator shaft, then the actuator size and weight are reduced, but shaft tilting may occur due to frictional forces
Solution Approach 1:
The patent addresses shaft tilting concerns by optimizing the bushing's geometric parameters, specifically setting the length-to-diameter ratio between 2 and 3. This parameter optimization ensures the single bushing has sufficient length to provide stable support and minimize tilting while maintaining a compact design. The bushing material and friction coefficients are also considered in the design to prevent excessive friction that could cause shaft tilting.
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 single-bushing design enables actuator shaft motion without shaft tilting, reduces the overall size and weight of the actuator, and enhances reliability by separating the actuator and crank cavities, allowing for a controlled environment and improved sealing.
Implementation Method 1
pneumatic cup at a first end... allowing actuator motion under set operating conditions
Implementation Method 2
The single bushing can be configured to support the actuator shaft... allowing actuator motion under set operating conditions
Data Source
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AI summary
A pneumatic actuator can include a housing (101) and an actuator shaft (103) disposed within the housing (101) and configured to actuate between a first position and a second position. The pneumatic actuator can include a single bushing located within the housing (101) between the housing (101) and the actuator shaft (103). The single bushing can be configured to support the actuator shaft (103) without the actuator shaft (103) being supported at a second location while allowing actuator motion under set operating conditions.