Static Pressure Seal Motor for Semiconductor Processes
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Solution Overview
Problem
Existing static pressure seal-equipped motors in semiconductor manufacturing processes face challenges in compactness, complexity, and size due to the need for increased axial length for sealing and exhaust ports, which can lead to foreign matter leakage and corrosive gas infiltration.
Innovation Solution
The motor design incorporates first and second static pressure seal portions with seal rings on the rotating motor shaft, an encoder cover, and a partition plate communication path, allowing for external sealing gas supply and exhaust, reducing motor complexity and size while preventing foreign matter and corrosive gas infiltration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sealed spaces are formed on both sides of motor bearings and static pressure seals are provided on the motor case, then sealing performance is improved, but the structure becomes more complex and the motor size increases
Solution Approach 1:
The patent extracts the sealing function from the motor case structure and relocates it to the rotating motor shaft. By providing static pressure seals directly on the shaft at the front and rear end surfaces, the sealing function is separated from the case, reducing structural complexity while maintaining effective sealing performance.
Solution Approach 2:
The patent introduces a sealed space formed by the side surface of the rotating motor shaft as an intermediary between the external environment and the motor chamber. This sealed space, pressurized by sealing gas supplied through supply ports, acts as a mediator to prevent foreign matter infiltration without requiring complex seal structures on the motor case.
2Object-generated harmful factors
If an exhaust port is provided on the motor case to exhaust gas from the motor chamber, then gas exhaustion is achieved, but the axial length of the motor increases
Solution Approach 1:
The patent changes the dimension of the exhaust port from the radial direction (on the motor case) to the axial direction (on the encoder cover). By providing the exhaust port on the encoder cover at the rear end of the motor shaft, gas can be exhausted axially without increasing the radial dimensions or requiring additional axial space in the motor case, thus avoiding motor enlargement.
3Reliability
If the distance from bearing position to seal position is increased to ensure sealing performance, then sealing reliability is improved, but shaft vibration increases
Solution Approach 1:
The patent applies preliminary action by pressurizing the sealed space with sealing gas before foreign matter can infiltrate through the static pressure seal. The sealing gas is supplied in advance through supply ports to maintain positive pressure in the sealed space, preventing foreign matter entry without requiring increased distance between bearing and seal positions, thus avoiding shaft vibration.
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 configuration effectively seals gaps between motor and rotating parts, prevents foreign matter and corrosive gas leakage, and allows for direct exhaust from the encoder cover, enhancing motor compactness and reliability without increasing axial length.
Implementation Method 1
the internal pressure within the sealed space is higher than the internal pressure within the motor chamber formed between the motor bearings
Implementation Method 2
a first seal ring for forming a first sealing gap with an outer circumferential surface of the first shaft end portion, the first sealing gap being sealed by a sealing gas supplied from the exterior
Data Source
AI summary
A static pressure seal-equipped motor in which front and rear gaps are sealed by first and second static pressure seal portions disposed at first and second axial end portions of a motor rotating shaft protruding toward front and rear. Sealing gas supplied to sealing gaps of the first and second static pressure seal portions is caused to diverge and flow to chemical liquid atmospheres and a motor chamber or an encoder chamber into the chemical liquid atmospheres, and also prevent entry of chemical liquid-containing gas from the chemical liquid atmospheres into the motor chamber or encoder chamber.