Car A/C Evaporator Valve Timing for Cold Accumulator Charging
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Solution Overview
Problem
Air conditioning systems with cold accumulators face issues such as incomplete charging, reduced cooling capacity, and increased risk of frosting due to limited temperature switching ranges and delayed evaporation, leading to inefficient operation and uneven temperature distribution.
Innovation Solution
The method involves controlling the stop valve of the primary consumer branch with a predetermined opening time based on air inlet temperature and air mass flow, allowing for alternating charging and cooling modes, and independently managing the stop valve of the auxiliary consumer branch to optimize charging and prevent frosting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the temperature limit for switching from cooling to charging is increased to achieve 100% cold accumulator charging, then the charging efficiency is improved, but the cooling capacity is reduced and evaporator temperature becomes too high
Solution Approach 1:
The patent implements periodic switching between cooling and charging modes using multiple temperature thresholds. The system alternates between these modes based on temperature measurements, creating a rhythmic cycle that allows the cold accumulator to charge to 100% while maintaining adequate cooling capacity through proper timing and threshold selection.
Solution Approach 2:
The patent introduces multiple temperature parameters (minimum limiting value of 1-5°C, maximal limiting value of 4-10°C, and intermediate values of 8-12°C) to control the switching between cooling and charging modes. By changing these temperature parameters dynamically, the system resolves the contradiction between achieving complete charging and maintaining cooling capacity.
2Reliability
If the stop valve to the primary consumer branch is closed during charging mode, then the cold accumulator charging efficiency is improved, but the evaporator temperature drops too low causing frosting risk
Solution Approach 1:
The patent employs feedback control by continuously monitoring the evaporator temperature and using this information to determine when to switch between cooling and charging modes. The temperature measurement provides feedback that triggers mode switching at appropriate moments, preventing both over-charging (which would cause frosting) and under-charging (which would reduce efficiency).
Solution Approach 2:
The system uses periodic switching between cooling and charging modes based on temperature thresholds. This rhythmic alternation allows the evaporator temperature to be maintained within safe limits while still achieving efficient cold accumulator charging over complete cycles.
3Object-affected harmful factors
If the change from cooling to charging is delayed to avoid evaporator frosting, then the frosting risk is reduced, but the cooling performance is reduced and temperature distribution becomes uneven
Solution Approach 1:
The patent performs preliminary action by switching to charging mode at an intermediate temperature (8-12°C) before the evaporator temperature drops to the dangerous level (1-5°C). This advance switching prevents frosting from occurring in the first place, eliminating the need to delay the mode change and preserving cooling performance.
Solution Approach 2:
The patent replaces the simple binary switching mechanism with a more sophisticated temperature-based control system that uses multiple thresholds and intermediate states. This substitution allows for smoother transitions and better temperature management, maintaining cooling performance while preventing frosting.
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 enables full charging of the cold accumulator while maintaining cooling capacity, reducing the risk of frosting, and achieving a more homogeneous temperature distribution at the evaporator, thereby improving operational efficiency and reliability.
Implementation Method 1
an evaporator (20) from which the refrigerant returns again to the compressor (10) by way of a suction line (22). The air to be climatized of the operator's cab flows through the evaporator (20) and is thus cooled off
Implementation Method 2
at least one auxiliary consumer branch that is connected in parallel and has a cold accumulator (30) and its own evaporator (28)
Data Source
AI summary
In an air conditioning unit for a car, which air conditioning unit has a refrigerant circuit with a primary consumer branch having a compressor, condenser, and an evaporator, which air conditioning unit also has at least one auxiliary consumer branch that is connected parallel to the primary consumer branch and has a cold accumulator and its own evaporator, a stop valve is arranged in front of each evaporator. After operational phases charging the cold accumulator, the stop valve of the primary consumer branch is regularly opened for only a predetermined opening time that depends on particular operating parameters. The substantial operating parameters are the air inlet temperature and the air mass flow at the evaporator of the primary consumer branch.