Multistage Vacuum Pump Rotor Segmentation for Gas Evacuation

Solution Overview

Problem

Conventional evacuation apparatuses face challenges in evacuating large quantities of process gas while maintaining a vacuum state, leading to motor overload and potential pump rotor contact with the casing due to increased heat and power consumption.

Innovation Solution

The apparatus employs a first vacuum pump with multistage pump rotors, where the inlet-side rotor has a larger axial width than the outlet-side rotor, and a second vacuum pump, allowing for controlled rotational speeds based on gas temperature, pressure, and motor current to prevent motor overload and rotor expansion, with both pumps housed in a single enclosure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If large-sized pump rotors or increased rotational speed are used to evacuate large quantity of process gas, then pumping speed is improved, but motor becomes overloaded and power consumption increases

Engineering Contradiction:

Improvepumping speedVSAvoidpower consumption

Core Design Contradiction:

ProductivityVSUse of energy by moving object

Solution Approach 1:

The pump rotor is divided into multiple stages along the axial direction, with each stage having progressively smaller axial widths. This segmentation allows the rotor to process gas in multiple compression stages rather than requiring a single large rotor or high speed, thereby reducing motor load and power consumption while maintaining high pumping speed capability

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention changes the geometric parameters of the pump rotor by creating a multistage structure with varying axial widths. The inlet-side rotor has larger axial width for gas intake, while outlet-side rotors have progressively smaller axial widths, optimizing the compression process across stages and improving overall system efficiency

Inventive Principle:

Principle #35Parameter changes

2Productivity

If large-sized pump rotors or increased rotational speed are used to evacuate large quantity of process gas, then pumping speed is improved, but motor becomes overloaded

Engineering Contradiction:

Improvepumping speedVSAvoidmotor load

Core Design Contradiction:

ProductivityVSPower

Solution Approach 1:

The pump rotor is divided into multiple stages along the axial direction, with each stage having progressively smaller axial widths. This segmentation allows the rotor to process gas in multiple compression stages rather than requiring a single large rotor or high speed, thereby reducing motor load and power consumption while maintaining high pumping speed capability

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention changes the geometric parameters of the pump rotor by creating a multistage structure with varying axial widths. The inlet-side rotor has larger axial width for gas intake, while outlet-side rotors have progressively smaller axial widths, optimizing the compression process across stages and improving overall system efficiency

Inventive Principle:

Principle #35Parameter changes

3Productivity

If pump rotors are operated at high speed or for extended periods, then pumping performance is improved, but pump rotors expand due to heat and may contact rotor casing

Engineering Contradiction:

Improvepumping performanceVSAvoidrotor contact prevention

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The pump rotor is divided into multiple stages along the axial direction, with each stage having progressively smaller axial widths. This segmentation allows the rotor to process gas in multiple compression stages rather than requiring a single large rotor or high speed, thereby reducing motor load and power consumption while maintaining high pumping speed capability

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention changes the geometric parameters of the pump rotor by creating a multistage structure with varying axial widths. The inlet-side rotor has larger axial width for gas intake, while outlet-side rotors have progressively smaller axial widths, optimizing the compression process across stages and improving overall system efficiency

Inventive Principle:

Principle #35Parameter changes

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 enables efficient evacuation of large gas quantities while reducing motor load, preventing rotor contact and minimizing power consumption, thereby maintaining a stable vacuum state.

Implementation Method 1

a small gap is formed between the pump rotors and also between the pump rotors and an inner surface of the rotor casing, so that these pump rotors can be rotated in the rotor casing in a non-contact manner

Methodology Applied

Scientific EffectCompression: Compression

Implementation Method 2

a motor for driving the booster pump is overloaded

Methodology Applied

Scientific EffectElectromagnetic conversion: Electromagnetic Induction

Implementation Method 3

the pump rotors are likely to expand due to heat of compression of the process gas and heat generated by the motor

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentUS9541088B2Evacuation apparatus

Publication Date: 2017.01.10 EBARA CORP

AI summary

The present invention relates to an evacuation apparatus for evacuating a vacuum chamber of a substrate processing apparatus for processing a substrate such as a semiconductor wafer or liquid crystal panel. An evacuation apparatus according to the present invention includes a first vacuum pump connected to a vacuum chamber, and a second vacuum pump connected to the first vacuum pump. The first vacuum pump has a pair of multistage pump rotors.