Vacuum Pump Exhaust Duct Thermal Coupling for Deposition Control
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Solution Overview
Problem
Vacuum pumps in semiconductor and liquid crystal manufacturing devices face product deposition issues, leading to reduced pump performance and shortened rotor life due to increased back pressure and heat generation, which existing solutions attempt to address with additional heating components.
Innovation Solution
A vacuum pump design featuring a stator and rotor with a second exhaust duct in thermal contact with the stator, which is heated through radiant and frictional heat, reducing product deposition without the need for additional heating components like electric heaters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a partition wall made of a heat transfer body is provided and a heating section is added to reduce product deposition, then product deposition is reduced, but device complexity increases due to additional heaters, temperature sensors, and controllers
Solution Approach 1:
The exhaust duct utilizes the pump's own operational heat (from gas friction and radiant heat from the stator) to prevent product deposition, eliminating the need for external heating systems. The system serves itself by converting waste heat into a useful function for maintaining duct temperature and preventing deposition.
Solution Approach 2:
The heating function is extracted from the pump body and transferred to the exhaust duct structure itself. The exhaust duct is designed to be thermally coupled with the stator, allowing it to independently utilize heat without requiring separate heating components mounted on the pump.
2Object-affected harmful factors
If the exhaust duct is heated to reduce product deposition, then product deposition is reduced, but manufacturing precision requirements increase due to thermal expansion and contraction
Solution Approach 1:
The design accepts and utilizes thermal parameter changes (expansion and contraction) as functional characteristics rather than errors to be eliminated. The exhaust duct is designed with thermal coupling to the stator, allowing it to expand and contract with temperature changes while maintaining proper fit and function through the thermal contact design.
3Object-affected harmful factors
If additional heating components are added to the exhaust duct, then product deposition is reduced, but maintenance frequency increases due to more components that can fail
Solution Approach 1:
The exhaust duct heating function is achieved through self-service by utilizing heat already present in the system (gas friction heat and radiant heat from the stator). No additional heating components are required, eliminating potential failure points and reducing maintenance needs.
4Productivity
If the pump back pressure rises due to duct blockage, then pump performance decreases, but the rotor creep life is lowered due to increased heat generation
Solution Approach 1:
The exhaust duct is pre-heated through thermal coupling with the stator to prevent product deposition before it can accumulate and cause blockages. This preliminary anti-action against deposition prevents the chain reaction that would lead to increased back pressure and rotor overheating.
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 improves maintainability by reducing product deposition on the exhaust ducts, extending the life of the rotor and maintaining pump performance without additional heating components, thus lowering maintenance frequency.
Implementation Method 1
the second exhaust duct is in thermal contact with the stator
Implementation Method 2
the stator and a rotor that rotates with respect to the stator
Implementation Method 3
heated through radiant and frictional heat
Data Source
AI summary
A vacuum pump comprises: a stator; a rotor that rotates with respect to the stator; a pump casing in which the stator and the rotor are contained, and a suction port and a through-hole for exhaust are provided; a first exhaust duct fixed to an outer circumference of the pump casing so as to communicate with the through-hole for exhaust; and a second exhaust duct that is inserted into at least the through-hole for exhaust with a gap interposed, an exhaust gas passing inside the second exhaust duct.