Air conditioning device for a motor vehicle and method for operating same
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Solution Overview
Problem
Existing air conditioning devices for motor vehicles lack independence in the operation of the first evaporator and coupling heat exchanger, leading to inflexible cooling capacity adjustments that affect climate comfort and require expensive electronic expansion valves.
Innovation Solution
A branch line is introduced in the refrigerant circuit upstream of the first expansion element, allowing for additional refrigerant flow through a controllable branch line expansion element, which increases evaporable refrigerant to the coupling heat exchanger during high cooling demand without affecting the first evaporator's cooling capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an electronic expansion valve is used to control the first evaporator for flexible refrigerant flow adjustment, then the adaptability of the system is improved, but the manufacturing cost is increased
Solution Approach 1:
The control function is segmented between two expansion elements: a thermostatic expansion valve for the main circuit and a controllable expansion element for the branch line. This segmentation allows the cheaper thermostatic valve to handle the primary refrigerant distribution while the branch line handles flexible adjustments, reducing overall system cost while maintaining adaptability.
Solution Approach 2:
Instead of using an expensive electronic expansion valve in the main circuit, the invention creates a parallel branch line with its own expansion element that replicates the flow control function specifically for electronics cooling. This copying approach provides the needed flexibility without requiring expensive components in the main circuit.
2Adaptability or versatility
If multiple evaporators are connected in parallel for zone air conditioning, then the versatility of the system is improved, but the risk of oil trapping in unused evaporators increases, reducing reliability
Solution Approach 1:
The electronics cooling function is extracted from the parallel evaporator configuration and placed in a separate branch line. This extraction ensures that the branch line serving the coupling heat exchanger remains actively circulated even when the first evaporator is unused, preventing oil trapping while maintaining the versatility of having multiple cooling zones.
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 provides flexible cooling capacity adjustments in the coolant circuit without compromising passenger compartment comfort, using a cost-effective thermostatic expansion valve for the main circuit and a controllable expansion element for the branch line.
Implementation Method 1
the refrigerant circuit and the coolant circuit are thermally coupled to one another by means of a coupling heat exchanger designed as a coolant/refrigerant heat exchanger
Implementation Method 2
there is still a residual amount of vaporizable refrigerant at its outlet, which can vaporize in the downstream coupled heat exchanger
Implementation Method 3
an air/refrigerant heat exchanger that can be operated as a first evaporator
Data Source
Figure 1
AI summary
The invention relates to an air conditioning device for a motor vehicle, comprising: - a refrigerant circuit (10) with a refrigerant main circuit (12) comprising a compressor (20), a condenser/gas cooler (30), a first expansion element (51) and an air/refrigerant heat exchanger operable as a first evaporator (41), which are arranged in the refrigerant main circuit (12) in this order in the direction of refrigerant flow, and - a coolant circuit (70) with a coolant pump and a heat exchanger thermally coupled to a heat source, wherein the refrigerant circuit (10) and the coolant circuit (70) are thermally coupled to each other by means of a coupling heat exchanger (60) designed as a coolant/refrigerant heat exchanger, which is connected downstream of the first evaporator (41) in the direction of refrigerant flow and can also be operated as an evaporator.The invention is characterized in that a branch line (14), which branches off from the main refrigerant circuit in the direction of flow of the refrigerant upstream of the first expansion device (51), opens back into the main refrigerant circuit (12) between the first evaporator (41) and the coupling heat exchanger (60) and has a controllable branch line expansion device (141).