Vacuum Pump Frequency Converter Cooling via Liquid-Cooled Air
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Solution Overview
Problem
Existing vacuum pump designs face challenges in reliably cooling frequency converters, particularly under high thermal loads, and often result in condensation issues and increased maintenance due to exposure to vibrations and contamination risks.
Innovation Solution
A vacuum pump design that integrates both an air cooler and a liquid cooler within a single frequency converter housing, where the liquid cooler surrounds the electric motor and cools the air flow, preventing condensation and reducing vibration exposure, while sharing a coolant circuit with the vacuum pump for simplified cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If air cooling is used for the frequency converter, then the cooling structure is simple, but high protection classes cannot be implemented and contamination risk increases
Solution Approach 1:
The cooling system is segmented into two independent parts: air cooling for the frequency converter and liquid cooling for the vacuum pump. This segmentation allows each component to be cooled according to its specific requirements while maintaining high protection classes. The frequency converter housing can be sealed (IP54) because the liquid cooling circuit is isolated in a separate heat exchanger system.
Solution Approach 2:
A heat exchanger acts as an intermediary between the liquid cooling circuit and the air cooling circuit. The liquid cooler cools the air flow that then cools the frequency converter, preventing direct water exposure to the frequency converter while still providing effective cooling. This intermediary approach resolves the contradiction between simple cooling structure and contamination protection.
2Temperature
If direct water cooling is used for the frequency converter, then cooling efficiency is high, but the frequency converter is exposed to vibrations and condensation risk
Solution Approach 1:
The cooling functions are segmented: liquid cooling handles the vacuum pump directly, while air cooling (mediated by liquid-cooled air) handles the frequency converter. This segmentation prevents the frequency converter from being exposed to vibrations and condensation risks associated with direct water cooling, while still maintaining high cooling efficiency through the liquid-cooled air pathway.
Solution Approach 2:
The liquid cooler serves as an intermediary that cools the air flow, which then cools the frequency converter. This indirect cooling approach maintains high cooling efficiency (comparable to direct water cooling) while eliminating the harmful effects of direct water exposure, including vibrations and condensation formation on the frequency converter.
3Reliability
If the frequency converter is arranged separately in a switch cabinet, then cooling and vibration protection are improved, but the system complexity and wiring requirements increase
Solution Approach 1:
The frequency converter housing is merged with the vacuum pump housing to form an integrated unit. This merging allows the frequency converter to benefit from the vacuum pump's vibration-isolated environment and integrated liquid cooling system, while avoiding the complexity of separate switch cabinets and extensive wiring. The frequency converter is protected from vibrations through the pump housing structure and from condensation through the sealed design with liquid-cooled air cooling.
4Device complexity
If cooling fins are provided on the frequency converter housing for natural convection, then no additional cooling device is needed, but the pump must be operated in a limited power range and ambient temperatures must be low
Solution Approach 1:
The liquid cooling system serves multiple functions: it cools the vacuum pump directly and also cools the air flow that cools the frequency converter. This multi-functionality allows the system to handle high thermal loads from both components simultaneously, enabling the pump to operate in a wider power range and higher ambient temperatures without requiring additional cooling devices.
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 ensures reliable cooling of the frequency converter, reduces condensation risks, and achieves a high protection class (IP54) by minimizing direct water exposure and using vibration-damping elements, thus enhancing operational reliability and reducing maintenance needs.
Implementation Method 1
The cooling takes place here by ambient air, which is sucked in by a fan and blown in the direction of the frequency converter. The cooling thus takes place through forced convection.
Implementation Method 2
both an air cooler and a liquid cooler are arranged in the frequency converter housing for cooling the frequency converter
Implementation Method 3
The liquid cooler at least partially surrounds the electric motor
Implementation Method 4
The liquid cooler is used on the one hand to cool the electric motor
Data Source
AI summary
The invention relates to a vacuum pump comprising pump elements (14) in a suction chamber (12). One of the pump elements (14) is driven by an electric motor (24). A frequency converter (30) is provided for changing the rotational speed of the electric motor (24). The frequency converter (30) is arranged in a frequency converter housing (32) connected directly to the pump housing (10). An air cooler (34) and a liquid cooler (36) are arranged inside the frequency converter housing (32), for cooling the frequency converter (30).