Heating-Circuit Defroster Control for Vehicle Fogging and Odor Prevention
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Solution Overview
Problem
Conventional vehicle air conditioners face issues with fogging and bad odor generation during defrosting operations due to water evaporation on the cooling heat exchanger surfaces, which leads to a switch from cooling to heating circuits, causing discomfort and air quality issues.
Innovation Solution
The air conditioner incorporates a defroster control portion that maintains the refrigerant cycle in the heating circuit during defrosting, preventing water wetting on the cooling heat exchanger surfaces and includes a ventilation-mode portion to introduce outside air after defrosting, ensuring the vehicle compartment temperature is maintained and preventing fogging and bad odor generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the refrigerant cycle is switched from cooling circuit to heating circuit during defrosting operation, then the defrosting function is achieved, but water on the cooling heat exchanger surface evaporates causing fogging and bad odor
Solution Approach 1:
The system performs preliminary heating of air before it reaches the cooling heat exchanger during defrosting operation. The heating heat exchanger is activated in advance to warm the air stream, preventing the temperature drop that would cause water evaporation and subsequent fogging or bad odor generation on the cooling heat exchanger surface.
Solution Approach 2:
The patent introduces a temperature adjustment mechanism as an intermediary between the heating and cooling circuits. By adjusting the temperature of air passing through the system using the heating heat exchanger, the direct harmful interaction between the cooling heat exchanger and evaporating water is prevented, eliminating fogging and odor issues.
2Temperature
If the temperature of air blown into the vehicle compartment is increased during defrosting, then defrosting effectiveness is improved, but the refrigerant cycle may switch to cooling circuit causing water wetting on heat exchanger
Solution Approach 1:
The system employs feedback control by monitoring the refrigerant cycle state and air temperature continuously. When defrosting is detected, the control system adjusts the heating heat exchanger operation to maintain appropriate air temperature while preventing unwanted cycle switching that would cause water wetting on the cooling heat exchanger.
Solution Approach 2:
The heating heat exchanger serves as an intermediary device that mediates between the need for high air temperature (for effective defrosting) and the need to prevent water wetting on the cooling heat exchanger. By controlling the heating process through this intermediary, the system achieves defrosting effectiveness without causing harmful water accumulation.
3Object-generated harmful factors
If the refrigerant cycle remains in heating circuit during defrosting, then water wetting on cooling heat exchanger is prevented, but air temperature control may be insufficient
Solution Approach 1:
The patent merges the functions of the heating heat exchanger and the defrosting control system. By combining the heating function with the defrosting operation, the system maintains the refrigerant cycle in the heating circuit to prevent water wetting on the cooling heat exchanger, while simultaneously achieving adequate air temperature control through the integrated heating mechanism.
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 effectively prevents fogging and bad odor generation by keeping the refrigerant cycle in the heating circuit during defrosting and using outside air ventilation post-defrosting, enhancing comfort and air quality within the vehicle compartment.
Implementation Method 1
a heating heat exchanger to heat air blown into a vehicle compartment by heat exchange with refrigerant flowing through the heating heat exchanger
Implementation Method 2
a cooling heat exchanger to cool air blown into the vehicle compartment by heat exchange with refrigerant flowing through the cooling heat exchanger
Implementation Method 3
The defroster control portion is configured to increase a temperature of air blown into the vehicle compartment through the defroster air outlet
Data Source
AI summary
An air conditioner for a vehicle includes a cycle switching device. The cycle switching device switches a refrigerant cycle between a heating circuit, in which refrigerant flows through a heating heat exchanger, and a cooling circuit, in which refrigerant flows through a cooling heat exchanger. The air conditioner further includes an air conditioning controller, which controls the cycle switching device and includes a defroster control portion. The defroster control portion increases a temperature of air blown into the vehicle compartment through a defroster air outlet by a predetermined degree while keeping the refrigerant cycle at a state of the heating circuit for a predetermined time, when a defrosting operation is commanded to be performed during the heating circuit.