Vacuum Pump Heat-Insulating Wall for By-Product Buildup
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Solution Overview
Problem
By-products such as chlorine-based or fluorine-based gases tend to precipitate and accumulate in the flow path downstream of the thread groove pump, leading to reduced performance in vacuum pumps used in semiconductor manufacturing, due to temperature differences and stagnation of gas flow.
Innovation Solution
A vacuum pump design featuring a heat insulating wall with specific corner and tubular shapes to minimize gas stagnation, coupled with a heater to maintain high temperatures and a smooth flow path, reducing the likelihood of by-product accumulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thread groove stator is heated to high temperature to prevent by-product precipitation, then by-product accumulation is suppressed, but the gas flow may stagnate in low temperature portions and by-products still accumulate
Solution Approach 1:
The patent applies local quality by creating different temperature zones in specific locations. The heat insulating wall is strategically placed to maintain high temperature in the thread groove stator while allowing other portions to remain at lower temperatures. This localized thermal management prevents by-product accumulation in the thread groove area without causing stagnation in other flow path regions.
Solution Approach 2:
The heat insulating wall segments the flow path into distinct thermal zones. By dividing the flow path with this insulating structure, the patent prevents mixed temperature effects that would cause stagnation while maintaining the necessary high temperature in the thread groove stator for by-product prevention.
2Ease of operation
If a ring-shaped heat insulating wall is formed to transfer gas to the outlet port, then gas flow is directed, but recessed portions cause gas stagnation and by-product accumulation
Solution Approach 1:
The patent applies spheroidality by forming arc-shaped corner portions instead of recessed angles in the heat insulating wall. The curved surfaces eliminate dead zones where gas could stagnate, ensuring continuous flow while maintaining the ring-shaped structure's ability to direct gas toward the outlet port.
3Temperature
If the flow path is formed between heated high temperature portion and cooled portion, then temperature control is achieved, but gas precipitates as by-products in low temperature portion
Solution Approach 1:
The patent extracts the low temperature cooled portion from direct contact with the gas flow path by placing the heat insulating wall between them. This separation removes the harmful cold zone that would cause by-product precipitation while preserving the temperature control function in other areas.
Solution Approach 2:
The heat insulating wall acts as an intermediary barrier between the heated high temperature portion and the cooled portion. It prevents direct thermal interaction that would create temperature gradients causing by-product precipitation, while still allowing the system to maintain necessary temperature control.
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 design effectively suppresses the precipitation and accumulation of by-products, maintaining the vacuum pump's performance by ensuring a continuous flow and reducing thermal conduction, thereby preventing flow path narrowing.
Implementation Method 1
the thread groove stator is heated to a high temperature by a heater or the like so that the flow path is not blocked by the precipitation of by-products in the exhaust gas
Implementation Method 2
a stator column, which encloses electrical components such as an electromagnet and a motor that drive the rotor to rotate, is cooled to a predetermined temperature or lower by a water cooling pipe or the like
Implementation Method 3
a part of a low temperature member adjacent to the flow path downstream of the thread groove is covered with a high temperature heat insulating wall. The heat insulating wall restricts the exhaust gas downstream of the thread groove from coming into contact with the low temperature portion
Data Source
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AI summary
Provided is a vacuum pump capable of suppressing the precipitation and accumulation of by-products in a flow path downstream of a thread groove of the vacuum pump provided with the thread groove. The vacuum pump includes a casing having an inlet port or an outlet port, a rotor provided with a plurality of rotor blades and a rotor cylinder portion, a driving portion, a bearing, stator blades, a thread groove stator that is disposed downstream of the stator blades and has an inner peripheral surface facing an outer peripheral surface of the rotor cylinder portion, and a heat insulating wall disposed downstream of the thread groove. The heat insulating wall includes a ring-shaped annular portion, and a substantially cylindrical wall portion extending from an inner portion of the annular portion in the radial direction to the upstream side and forming a flow path on the outer peripheral surface side. A first corner portion is formed between an upstream-side surface of the annular portion and the outer peripheral surface of the wall portion, the first corner portion being formed in an arc shape.