Vehicle Coolant Circuit Layout for Heating Temperature Limitation
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Solution Overview
Problem
Existing vehicle refrigerant circuits face high material stress on the housing during heating operations, especially when using R744, and inefficient refrigerant extraction from dead volumes in AC and heating modes, leading to potential system inefficiencies and component damage.
Innovation Solution
A method and refrigerant circuit design that limits refrigerant temperature at the inlet of the inner heating condenser to a maximum value, using existing lines and shut-off elements to prevent refrigerant flow through the heating condenser during AC operation and employing a temperature and pressure monitoring system to manage refrigerant flow, and implementing a suction process from dead volumes using existing lines and expansion elements to prevent refrigerant loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If refrigerant flows through the inner heating condenser during heating operation, then heating function is achieved, but material stress on the housing increases due to high temperatures
Solution Approach 1:
The patent extracts the heating function from the inner heat exchanger by routing refrigerant flow through an external heating condenser instead. The inner heat exchanger is isolated from high-temperature refrigerant flow during heating operation, preventing material stress on the housing while the external condenser handles the thermal load.
Solution Approach 2:
The patent introduces an external heating condenser as an intermediary component between the refrigerant circuit and the heating application. This mediator absorbs the high-temperature refrigerant energy away from the inner heat exchanger and housing, protecting the housing materials while still providing the necessary heating function.
2Productivity
If refrigerant is extracted from dead volumes during mode switching, then system efficiency improves, but additional components and complexity are required
Solution Approach 1:
The patent makes existing components multi-functional by enabling them to perform refrigerant extraction in addition to their primary functions. The expansion elements and shut-off elements are used for both normal refrigerant flow control and for extracting refrigerant from dead volumes during mode transitions, eliminating the need for dedicated extraction components.
Solution Approach 2:
The system performs self-service by using its own existing infrastructure (lines, expansion elements, shut-off elements) to extract refrigerant from dead volumes. No external or additional components are needed - the system repurposes its own components to handle the extraction function that would otherwise require separate dedicated equipment.
3Loss of substance
If refrigerant remains in dead volumes during AC operation, then system simplicity is maintained, but refrigerant loss and underfilling occur
Solution Approach 1:
The patent performs preliminary action by extracting refrigerant from dead volumes before AC operation begins or before mode switching occurs. The control unit initiates extraction sequences that actively pull refrigerant out of inactive areas and redirect it to the active cooling circuit, preventing refrigerant loss and ensuring proper system filling before operation starts.
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
Prevents material damage to the air conditioning unit housing and ensures efficient refrigerant circulation by limiting refrigerant temperature and utilizing existing components for refrigerant extraction, thereby enhancing system performance and reducing the risk of underfilling.
Implementation Method 1
the refrigerant, which is compressed and heated by means of a refrigerant compressor
Implementation Method 2
the refrigerant, which is compressed and heated by means of a refrigerant compressor
Implementation Method 3
Thermal energy can be transferred via the two gas coolers to the air flowing through the air conditioning unit
Implementation Method 4
A first expansion valve is connected downstream of the first heat exchanger, which allows the refrigerant to pass unthrottled during heat pump operation
Implementation Method 5
an evaporator, a refrigerant compressor, a first refrigerant condenser/gas cooler, a first expansion element assigned to the evaporator
Data Source
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AI summary
The invention relates to a method for operating a coolant circuit (2) of a vehicle air-conditioning system (1) in an AC mode and in a heating mode, implemented by means of a heat pump function, having an evaporator branch (2.1), comprising an evaporator (3) and a first expansion element (6.1), a coolant compressor (4), an AC and heat pump branch (2.2), having an outer condenser or gas cooler (5), as a heat pump evaporator having a second expansion element (6.2), wherein the AC and heat pump branch (2.2) is connected to the coolant compressor (4) via a first blocking element (A1) and to the evaporator branch (2.1) via the second expansion element (6.2), a heating branch (2.3) having an inner heating condenser or heating gas cooler (7) and a second blocking element (A2), connected downstream thereto, wherein the heating branch (2.3) is connected to the coolant condenser (4) via a third blocking element (A3) and to the evaporator branch (2.1) via the second blocking element (A2), a third expansion element (6.3), by means of which the heating branch (2.3) is connected to the AC and heat pump branch (2.2), and a temperature measuring means (T, pT1) for determining the coolant temperature at the inlet (E) of the inner heating condenser or heating gas cooler (7), wherein, in heating mode, the coolant temperature on the inlet (E) of the inner heating condenser or heating gas cooler (7) is restricted to a maximum temperature value.