Heat Pump Defrost Initiation Using Coolant Temperature Detection
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Solution Overview
Problem
Existing methods for initiating defrosting processes in heat exchangers of vehicle heat pumps are prone to false triggers due to external influences and temporary changes in suction pressure, leading to unnecessary defrosting cycles.
Innovation Solution
A method that determines the state of icing on a heat exchanger by monitoring the coolant outlet temperature from a coolant heat exchanger arranged in a common air path, initiating defrosting only when icing is confirmed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If suction pressure of the heat pump is monitored to initiate defrosting, then defrosting can be triggered when ice forms, but false triggers occur during motor vehicle start-up causing unnecessary defrosting processes
Solution Approach 1:
The patent introduces a coolant heat exchanger as an intermediary element that indirectly detects icing conditions. Instead of directly measuring parameters that are sensitive to external influences (suction pressure, fan current), the system uses the coolant heat exchanger's outlet temperature as a mediator that reflects icing conditions without being directly affected by temporary external disturbances during start-up.
Solution Approach 2:
The patent extracts the detection function from the heat pump system itself and places it in the coolant heat exchanger. By monitoring the coolant outlet temperature from a separate cooling circuit, the system separates the detection mechanism from the components (suction pressure sensor, fan motor) that are directly affected by start-up transients and external influences.
2Measurement precision
If additional sensor systems are used to measure ice layer thickness, then measurement precision improves, but device complexity increases
Solution Approach 1:
The patent makes the coolant heat exchanger serve multiple functions: it continues to cool the motor vehicle components (original function) while simultaneously acting as an icing detection sensor (new function). By monitoring the coolant outlet temperature, the same component provides both cooling and detection capabilities, eliminating the need for separate ice thickness measurement sensors.
Solution Approach 2:
The coolant heat exchanger performs self-detection of icing conditions by monitoring its own outlet temperature. The system uses the thermal state of the coolant after passing through the heat exchanger to infer icing conditions on the heat pump's ambient heat exchanger, allowing the system to monitor itself without additional external sensors.
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 reduces the sensitivity to external influences and allows for more accurate detection of icing, thereby minimizing unnecessary defrosting processes and ensuring efficient operation of the heat pump.
Implementation Method 1
a coolant outlet temperature of a coolant from the coolant heat exchanger is determined
Implementation Method 2
If the outside air falls below its dew point, frost forms on the surface of the heat exchanger
Implementation Method 3
frost forms on the surface of the heat exchanger, preventing the air from flowing through the heat exchanger
Data Source
AI summary
A method for initiating a defrosting process of a heat exchanger of a heat pump of a motor vehicle, wherein the heat exchanger and a coolant heat exchanger of a cooling circuit of the motor vehicle are arranged in a common air path, involves determining a coolant outlet temperature of a coolant from the coolant heat exchanger, determining a state of icing of the heat exchanger using the coolant outlet temperature, and initiating a defrosting process of the heat exchanger if icing of the heat exchanger is determined.