Method for operating an air conditioner for a motor vehicle
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Solution Overview
Problem
Existing air conditioning systems for vehicles struggle to efficiently heat and dehumidify the passenger compartment, especially at low ambient temperatures, leading to inadequate heating and misting issues, and inefficient operation due to reliance on waste heat from the engine cooling circuit, which affects fuel consumption and emissions.
Innovation Solution
A method for operating an air conditioner with a refrigerant circuit that switches between two heat sources (ambient air and engine coolant) based on temperature and pressure regulation, allowing for efficient heating, cooling, and dehumidification by determining and comparing temperature and pressure limits to optimize the air conditioner's operational mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If waste heat from the engine cooling circuit is used for heating the passenger compartment, then heating is provided, but at low ambient temperatures the temperature level is insufficient for comfortable heating
Solution Approach 1:
The refrigerant circuit is designed to perform multiple functions: it can operate as a cooling system, as a heat pump with ambient air as heat source, and as a heat pump with engine coolant as heat source. This multi-functionality allows the system to adapt to different ambient temperature conditions and provide sufficient heating temperature even at low ambient temperatures by switching between heat sources.
Solution Approach 2:
The system uses the engine coolant not only for engine cooling but also as a heat source for the refrigerant circuit when ambient temperature is not sufficiently low. The coolant serves dual purposes: cooling the engine and providing thermal energy for cabin heating, thereby making the system self-sufficient across a wider temperature range.
2Use of energy by moving object
If a heat pump with air as heat source is used, then heating efficiency is improved, but the system cannot simultaneously heat and dehumidify the air
Solution Approach 1:
The refrigerant circuit is configured to perform multiple functions including cooling, heating, and dehumidification. By having two distinct heat pump modes (one with ambient air, another with engine coolant), the system can select the appropriate mode based on whether dehumidification is required, thus maintaining both heating efficiency and the capability for simultaneous heating and dehumidification.
Solution Approach 2:
The system dynamically switches between different operational modes of the refrigerant circuit based on environmental conditions and cabin requirements. The control system adjusts the operating mode (cooling, heating with ambient air, heating with engine coolant) to meet the dynamic needs for heating and dehumidification simultaneously or separately.
3Temperature
If the internal combustion engine is run longer at low temperature to provide heat, then heating is maintained, but exhaust emissions and fuel consumption increase
Solution Approach 1:
The engine coolant serves dual purposes: it cools the engine and provides thermal energy to the refrigerant circuit for cabin heating. By utilizing the coolant's thermal energy that would otherwise be wasted, the system reduces the need to run the engine longer for heating purposes, thereby reducing fuel consumption and emissions while maintaining heating capability.
Solution Approach 2:
The system converts the waste heat from the engine coolant into useful heating energy for the passenger compartment. By capturing and utilizing this otherwise wasted thermal energy through the refrigerant circuit, the system reduces the need for additional fuel consumption and minimizes exhaust emissions while maintaining comfortable cabin temperature.
4Use of energy by moving object
If the internal combustion engine operates intermittently in hybrid vehicles, then fuel efficiency is improved, but the coolant temperature does not become sufficiently high for effective heat pump operation
Solution Approach 1:
The refrigerant circuit is designed with two heat pump modes: one using ambient air as heat source and another using engine coolant as heat source. This universality allows the system to switch to ambient air as heat source when the engine operates intermittently and coolant temperature is insufficient, thereby maintaining effective heat pump operation without compromising fuel efficiency.
Solution Approach 2:
The system changes the heat source parameter based on operating conditions. When the engine operates intermittently in hybrid vehicles and coolant temperature is insufficient, the system switches the heat source from engine coolant to ambient air, thereby adapting to the changed thermal conditions while maintaining heating effectiveness and fuel efficiency.
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 approach ensures high-efficiency operation across various modes, providing quick warm air delivery, minimizing energy consumption, and maintaining comfort by efficiently switching between heat sources and reducing the impact of low coolant temperatures on the engine.
Implementation Method 1
a refrigerant circuit for a combined cooling device and heat-pump mode as well as for a post-heating mode
Implementation Method 2
heat is transferred via the heating warmth exchanger to the air flowing into the passenger compartment
Implementation Method 3
a compressor for compressing the refrigerant
Implementation Method 4
an expansion valve with a bypass channel
Data Source
AI summary
The invention relates to a method for operating an air conditioner (1) for treating the air of a passenger compartment of a motor vehicle. The air conditioner (1) exhibits a refrigerant circuit (2) configured for a combined cooling unit and heat-pump mode and for a post-heating mode. In the heat-pump mode with a first and a second heat source, two heat sources differing from each other can be used. A temperature of the first heat source, a temperature of the second heat source, and a regulation characteristic number and a maximum pressure are taken into account in the refrigerant circuit (2) for operating the air conditioner (1) in a heat-pump mode. The invention additionally relates to a method for switching between the two heat-pump modes.