Segmented Heating Resistors for Vacuum Pump Thermal Management
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Solution Overview
Problem
Single-stage dry vacuum pumps, particularly in semiconductor processes, face challenges in maintaining gas temperatures to prevent condensation and mechanical malfunctions due to insufficient thermal energy at low pressures, and existing heating solutions like heating blankets are bulky, inefficient, and unsuitable for small pumps, affecting cooling and leading to deposit formation.
Innovation Solution
A pumping unit with two heating resistors, arranged in parallel planes perpendicular to the gas flow at the inlet and outlet, providing targeted thermal diffusion heating, integrated with temperature sensors and controllers to maintain optimal temperatures and ensure effective cooling of functional zones.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a heating blanket is used to maintain gas temperature in the pump body, then condensation and powder accumulation are prevented, but the pump body cannot be cooled in functional zones and lubricant areas, leading to temperature gradients and deposit formation
Solution Approach 1:
The heating system is segmented into multiple independent heating zones (first heating zone at inlet, second heating zone at outlet) that can be independently controlled. This allows different temperature profiles in different regions of the pump body, enabling gas heating in the compression stage while permitting cooling in functional zones, thus resolving the contradiction between preventing condensation and maintaining temperature gradients for proper lubrication.
Solution Approach 2:
Different regions of the pump body are assigned different thermal characteristics - the compression stage receives heating to prevent condensation, while functional zones (bearings, motor areas) are allowed to cool naturally or are actively cooled. This local differentiation of thermal properties enables simultaneous achievement of gas temperature maintenance and functional zone cooling, eliminating the need for a single blanket heating approach.
2Temperature
If thermal insulation blankets are used to heat the pump body, then gas temperature is maintained, but the heating is bulky and expensive, and installation is difficult on angular casings
Solution Approach 1:
The mechanical heating system (thermal insulation blankets) is replaced with an electrical heating system consisting of heating resistors integrated into the pump structure. These electric heating elements can be precisely positioned and controlled, eliminating the bulk and installation difficulties of blanket systems while providing more uniform and controllable heating.
Solution Approach 2:
The heating function is merged directly into the pump body structure through integrated heating zones and resistors. Rather than adding a separate blanket system, the heating elements are incorporated into the pump housing itself, eliminating the need for separate installation and reducing overall system bulk while improving manufacturing integration.
3Reliability
If heating is applied to the pump body to prevent condensation, then mechanical seizing is avoided, but cooling of bearings and lubricant is reduced, potentially causing thermal damage
Solution Approach 1:
The thermal management system is divided into separate heating zones that are spatially segmented from the bearing and lubricant areas. The first heating zone is positioned at the inlet and the second at the outlet, away from functional zones. This segmentation allows independent thermal control - heating the compression stage to prevent condensation while maintaining lower temperatures in bearing areas for proper lubrication.
Solution Approach 2:
Thermal insulation barriers are introduced as intermediaries between the heating zones and the functional zones (bearings, motor areas). These insulation layers prevent heat from the compression stage from transferring to the bearing areas, allowing the compression stage to be heated for condensation prevention while keeping bearing temperatures low enough for proper lubrication.
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 solution effectively prevents mechanical malfunctions by maintaining gases in a gaseous state, optimizing heating for the pump stage body while allowing controlled cooling of critical areas, reducing the risk of deposits and ensuring consistent operation.
Implementation Method 1
two heating resistors arranged respectively at the inlet and at the outlet of the gases, in planes parallel to each other and perpendicular to the direction of the gas to be pumped, so as to heat by thermal diffusion the stage body between inlet and outlet
Data Source
Figure 1
Figure 2~4
AI summary
The unit (1) has a single staged dry vacuum pump (2) e.g. single staged bilobed root pump, including a compression stage body (13) provided with gas inlet and outlet (15, 17). A heating unit has removable heating resistors (24, 29) arranged at the inlet and the outlet, respectively, in planes that are parallel between them and are perpendicular to directions (19, 21) of gas to be pumped to heat the body by thermal diffusion between the inlet and the outlet, where the resistors are in the form of circular arc shaped bands.