Vehicle HVAC Compressor Control for Refrigerant Oil Freeze Prevention
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Solution Overview
Problem
Existing vehicle HVAC systems face challenges in maintaining effective cabin heating performance, especially in low outdoor temperatures, due to refrigerant oil freezing and reduced compressor RPM, leading to increased energy consumption.
Innovation Solution
A vehicle HVAC system and method that control the inverter of the compressor based on refrigerant temperature, refrigerant oil freezing temperature, and compressor component temperature, allowing the compressor to operate in a heat generating mode to prevent refrigerant oil freezing and enhance cabin heating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the HVAC system operates in heating mode at low outdoor temperatures, then cabin heating is provided, but refrigerant oil freezing occurs and compressor RPM is restricted
Solution Approach 1:
The patent converts the harmful effect of low compressor RPM (which limits heating performance) into a beneficial heat source. By operating the compressor at reduced speed when refrigerant oil temperature approaches freezing point, the system generates heat through compression that warms the refrigerant oil, preventing freezing while maintaining acceptable heating performance.
Solution Approach 2:
The patent changes the operational parameters of the compressor by restricting maximum RPM when refrigerant oil temperature is low. The control unit adjusts compressor speed based on refrigerant oil temperature sensors, creating a parameter change that prevents oil freezing while maintaining system functionality.
2Reliability
If the compressor RPM is restricted to prevent refrigerant oil freezing, then refrigerant oil freezing is prevented, but cabin heating performance is reduced
Solution Approach 1:
The patent converts the restricted compressor operation (which would normally reduce heating capacity) into a beneficial heating source. The compression process itself generates heat that warms the refrigerant oil, and this heat is then transferred to the cabin through the HVAC system, turning a limitation into an advantage.
Solution Approach 2:
The compressor serves dual functions: it continues to circulate refrigerant for heating while simultaneously generating heat through compression that warms the refrigerant oil. The system uses its own compression heat to prevent oil freezing, making the compressor self-serving for both its primary function and the protective function.
3Use of energy by moving object
If the inverter operates in efficiency mode, then energy consumption is reduced, but heat generation is insufficient to prevent refrigerant oil freezing
Solution Approach 1:
The patent implements dynamic switching between efficiency mode and lossy mode in the inverter based on real-time refrigerant oil temperature conditions. When oil temperature is above the threshold, efficiency mode operates to save energy. When temperature approaches freezing point, the system dynamically switches to lossy mode to generate heat, preventing oil freezing.
Solution Approach 2:
The patent changes the operational parameters of the inverter by switching between different efficiency levels based on temperature conditions. The control unit monitors refrigerant oil temperature and adjusts inverter efficiency mode accordingly, creating a parameter change that balances energy consumption with heat generation needs.
4Reliability
If the inverter operates in lossy mode to generate heat, then refrigerant oil freezing is prevented, but energy consumption increases
Solution Approach 1:
The patent implements dynamic mode switching that allows the inverter to operate in lossy mode only when necessary (when refrigerant oil temperature approaches freezing point). This dynamic adjustment ensures heat generation occurs only when needed for protection, minimizing unnecessary energy consumption while maintaining reliability.
Solution Approach 2:
The patent applies partial action by using lossy mode only partially - specifically when temperature conditions require heat generation. The system doesn't continuously operate in lossy mode but applies it selectively based on temperature thresholds, using just enough excess energy consumption to prevent freezing without wasteful continuous operation.
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 solution effectively prevents refrigerant oil freezing and improves cabin heating performance by allowing the compressor to generate additional heat, thereby maintaining efficient operation and reducing energy consumption.
Implementation Method 1
a heat generating mode in which an inverter 32c controls a motor section 32b of the compressor 32 to operate in a lossy mode, thereby additional heat is generated from the compressor 32
Data Source
AI summary
A vehicle heating, ventilation, and air conditioning (HVAC) system is provided. The system includes a compressor having: a compression section; a motor section configured to drive the compression section; and an inverter configured to allow the motor section to operate in any one of an efficiency mode and a lossy mode. The system also includes a controller configured to control the inverter of the compressor based on a minimum temperature of a refrigerant and a freezing temperature of refrigerant oil contained in the refrigerant.