Active Aerostatic Bearing With Conical Gap Control
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Solution Overview
Problem
Aerostatic bearings face limitations in static stiffness and geometrical inaccuracies, leading to inaccuracies in high-precision machines, particularly in semiconductor manufacturing, due to their passive load compensation methods which increase manufacturing complexity and require pressurized chambers.
Innovation Solution
An active aerostatic bearing design featuring a first plate with a central recess and orifice for pressurized air, and a force actuator that causes conical deformation of the plate, allowing for improved mechanical stiffness and servo compliance without the need for gap measurement, using a parallelogram structure with pivoting points and a voice coil motor for actuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If passive load compensation methods are used (deformable membrane, pivoting membrane), then static stiffness is increased, but manufacturing complexity increases due to pressurized chambers
Solution Approach 1:
The patent replaces complex mechanical pressurized chamber systems with an electromagnetic actuator (voice coil motor) that directly deforms the plate to control gap geometry. This substitution of mechanical systems with electromagnetic actuation achieves high static stiffness without requiring additional pressurized chambers or complex mechanical structures.
Solution Approach 2:
The patent changes the physical state and geometry of the plate by applying electromagnetic force to create controlled deformation. By dynamically adjusting the plate's shape through the voice coil motor, the system achieves variable stiffness and gap geometry control without mechanical complexity.
2Ease of operation
If gap geometry control with plate deformation is used, then collocated actuation is achieved, but design complexity increases due to flexible plate requirements
Solution Approach 1:
The patent makes the plate dynamically deformable under electromagnetic actuation, allowing real-time adjustment of gap geometry. The plate transitions from a static component to a dynamic element that can be precisely controlled by the voice coil motor, enabling collocated actuation without rigid mechanical linkages.
Solution Approach 2:
The patent employs a thin, flexible plate structure that can be easily deformed by the electromagnetic actuator. This flexible plate design allows for simple implementation of gap geometry control without requiring complex mechanical mechanisms, achieving collocated actuation with minimal design complexity.
3Strength
If membrane-like thin plate is used for high mechanical stiffness, then local deformation occurs under point loading, but servo force impact on load capacity is limited
Solution Approach 1:
The patent transitions from point loading to distributed area loading by positioning the voice coil actuator beneath the plate. This dimensional change from a point source to an area source creates a more uniform pressure distribution, preventing local deformation while maintaining high mechanical stiffness and maximizing servo impact on load capacity.
Solution Approach 2:
The patent applies preliminary electromagnetic force to deform the plate into an optimal geometry before main loading occurs. By pre-shaping the gap geometry through the voice coil motor, the system prepares the plate to handle subsequent loads more effectively, preventing local deformation and maximizing the servo's impact on load capacity.
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 active aerostatic bearing achieves high passive mechanical stiffness for disturbance rejection and high servo compliance, enabling precise load capacity control with low actuator force, overcoming the limitations of prior art by maintaining position stability and compensating for geometrical inaccuracies.
Implementation Method 1
an electromagnetic actuator, in particular a voice coil motor
Implementation Method 2
pressurized air from a central nozzle. The pressurized air forms an air gap between a guiding surface and the first plate
Data Source
AI summary
An active aerostatic bearing comprises a first plate and a force actuator. The first plate has a central recess area including an orifice forming an inlet restrictor for pressurized air from a central nozzle. The pressurized air forms an air gap between a guiding surface and the first plate. The force actuator is configured to act to deform the first plate so as to change a shape of the air gap, wherein the actuator is configured to cause a conical deformation of the first plate.