Automatic control method used for defrosting a heat pump for a vehicle

Abstract

A control method for a heat pump system, or for a motor vehicle, which includes a compressor, an internal heat exchanger forming a condenser in a heating mode, an expansion valve, an outer heat exchanger forming an evaporator in the heating mode, and an accumulator. The defrosting of the outer exchanger is detected, the defrosting of the accumulator is detected, and depending on the case, defrosting the outer exchanger and / or defrosting the accumulator is started.

Description

TECHNICAL FIELD[0001]The present invention relates to the field of heat pump systems fitted to some types of motor vehicles, notably electric or hybrid vehicles. More specifically, it relates to a control method for the heat pump system of these vehicles, said method being used to defrost some components of said system when the external air temperature is low.PRIOR ART[0002]There is a known way of using a heat pump in vehicles for heating and / or air conditioning the passenger compartment of the vehicle. This heat pump is reversible so that it can operate in both heating mode and air conditioning mode. It conventionally comprises a compressor for heating and compressing a refrigerant fluid, an internal heat exchanger forming a condenser in heating mode for heating the internal air in the passenger compartment of the vehicle by heat exchange with the refrigerant fluid flowing from the compressor, an expansion valve for cooling the refrigerant fluid flowing from the internal heat excha...

AI Technical Summary

Benefits of technology

The patent describes a system for defrosting external parts of a vehicle's air conditioning system, such as the external exchanger and accumulator. Complete defrosting of these parts can require a lot of time and power, and can even increase the thickness of frost on other parts of the vehicle. By using a specific motor speed to circulate hot refrigerant fluid through the external exchanger and accumulator, the system can quickly melt the frost and ensure optimal performance. The defrosting operation is only started if the vehicle is going below a certain speed, to prevent unnecessary energy consumption. The technical effect of this patent is to provide an efficient and effective solution for defrosting external parts of an air conditioning system in a cost-effective way.

Problems solved by technology

This frosting of the external exchanger then leads to a decrease in the efficiency of the heat pump, which increases the electricity consumption for the same performance level, or reduces the performance for the same level of electricity consumption.

This also reduces the maximum power of the system.

This solution is not satisfactory, because it increases the total electricity consumption of the system, which has negative effects in the case of electric or hybrid vehicles.

However, other parts of the heat pump become frosted, notably the low pressure pipes and the accumulator, which is detrimental to the performance of the heat pump and which, because of the successive accumulation of frost on the walls of these elements and the proximity of other elements in the immediate environment, risks causing noise and may result in consequential damage.

Therefore, frost forms on the walls of these elements as well, when the external temperature is low.

Furthermore, during the defrosting of the external exchanger, the temperature of the fluid supplied to the accumulator has already fallen considerably because said fluid has already released much of its heat in the external exchanger to cause the melting of the frost present on the walls of the latter.

This presence of frost on the accumulator has the disadvantage that it not only lowers the performance of the heat pump by keeping the fluid contained in the accumulator at a low temperature, but also increases the proximity of the exchanger to other parts of the vehicle, thus increasing the risk of impact with these other parts, increasing the risk of noise due to these impacts, and increasing the risk of degradation of the accumulator and of these parts.

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