Air conditioning system

Abstract

An air conditioning system, in particular for a motor vehicle, comprising a refrigerant circuit having at least one compressor, and comprising a coolant circuit having an external heat exchanger which is arranged in a heat pump system, wherein a redundant heat source is provided which is integrated in the heat pump system.

Claims

1. An air conditioning system for a motor vehicle, comprising: a refrigerant circuit having at least one compressor; and a coolant circuit having an external heat exchanger that is arranged in a heat pump system, the external heat exchanger being a first heat source in the heat pump system, wherein a redundant heat source is integrated in the heat pump system, the redundant heat source being a second heat source in the heat pump system wherein the redundant heat source is arranged directly upstream of the external heat exchanger; and an internal heat exchanger arranged between a collecting tank and an evaporation unit of the refrigerant circuit.

2. The air conditioning system according to claim 1, wherein the compressor is operated with different rotational speeds.

3. The air conditioning system according to claim 1, wherein the coolant circuit includes a heater and wherein the redundant heat source is arranged in a flow of the coolant circuit downstream of the heater.

4. The air conditioning system according to claim 1, wherein the redundant heat source is an electrical heat source.

5. The air conditioning system according to claim 4, wherein the electrical heat source is an electric heating device.

6. The air conditioning system according to claim 1, wherein a volume flow through the external heat exchanger is less than a total volume flow of the coolant circuit.

7. A motor vehicle comprising an air conditioning system according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus, are not limitive of the present invention, and wherein:

(2) FIG. 1 shows an air conditioning system according to the invention with a redundant heat source, and

(3) FIG. 2 shows a diagram of air temperature values at the heater.

DETAILED DESCRIPTION

(4) FIG. 1 shows a heat pump system 10 of an air conditioning system, which is not illustrated in detail, of a motor vehicle which is not illustrated. The air conditioning system can serve for air-conditioning an interior of the motor vehicle. The heat pump system 10 has a coolant circuit 32 and a refrigerant circuit 12. The refrigerant circuit 12 is a closed circuit through which a refrigerant can flow. The refrigerant circuit 12 has, among other things, a compressor 14, an internal heat exchanger 18, an evaporation unit 20 that operates as a chiller, a collecting tank 22 and in indirect condenser 24. In addition to an external heat exchanger 16 and valves 28, 30, 34 and 36, a cooler 38 and a heater 40 are arranged in the coolant circuit 32. The expansion valve of the refrigerant circuit is designated with 26. A redundant heat source 42 can principally be arranged at three positions 37, 39 45. Position 37 is arranged in the flow of the external heat exchanger 16. The position having the reference number 39 marked in the Figure designates the position in the flow of the heater 40.

(5) The valves 28, 30 are preferably formed as three-way valves 28, 30. More preferably, they are formed as solenoid valves. The valves 34 and 36 are formed as shut-off valves.

(6) During operation of the air conditioning system, air that is designated with the arrows 44 and 46 flows past the external heat exchanger 16 thereby extracting heat from the air. Thus, the external heat exchanger 16 supplies the coolant circuit 32 with energy in the form of heat. The evaporation unit 20 and the indirect condenser 24 are also connected to the coolant circuit 32. Through this, energy can be transferred from the refrigerant circuit 12 to the cooling water in the cooling water circuit 32.

(7) The redundant heat source 42 can be an electric heating device 42, which can easily be connected and disconnected. For this purpose, a control and regulating device can be provided which operates by using measured temperatures of the coolant in the coolant circuit 32 or of the outside air at the motor vehicle as the input control variable, for example. The redundant heat source 42 serves as an additional heat source for providing energy in a thawing mode, in particular at low outside temperatures and/or when condensate has accumulated in the external heat exchanger 16. In the thawing mode 16, the external heat exchanger serving as a heat pump is virtually replaced in its function as an energy source by the redundant heat source 42. Hereby, the desired temperature of the cooling water at the location of the heater 40 can be maintained. Through this, the air temperature in the interior of the vehicle can remain the same even if the energy source air is no longer available.

(8) The position 37 of the redundant heat source 42 is the preferred position here. Here, the redundant heat source 42 is arranged directly upstream of the outside heat exchanger 16. If the redundant heat source 42 is arranged in position 39, it is additionally needed to reduce the volume flow of the cooling water flowing through the external heat exchanger 16. This, for example, can be carried out with proportional valves by means of which the volume flow can be adjusted.

(9) The redundant heat source 42 typically has an output of approximately 5 kW, preferably between 4 and 5 kW. However, heat sources, in particular electrical heat sources, which have a different output can also be used and can be controlled as needed. If the temperature is too low and/or the external heat exchanger is iced up, the temperature of the coolant is no longer sufficient and the redundant heat source 42 is connected. At position 37, directly upstream of the external heat exchanger 16, energy, for example in the form of heat energy, can be fed to the cooling water flowing through the external heat exchanger. There are no losses through or in the line system.

(10) The redundant heat source 42 is used when the air conditioning system is in the thawing mode since here the heat source air is not available at the external heat exchanger 16. The redundant heat source 42 is switched on exactly as long as the thawing mode is switched on. The air conditioning system can be operated in a mode in which a heating mode alternates with a thawing mode. Here, the redundant heat source 42 is then connected and disconnected accordingly.

(11) In FIG. 2, the air temperature at the heater 40 is plotted in a diagram on the y-axis as a function of time, plotted on the x-axis. A line with the reference number 48 describes the progression of the air temperature at the heater in the thawing process using the redundant heat source 42 at the position 39 without volume correction. Here, the entire volume flow flows through the external heat exchanger 16. As a result, the overall temperature at the heater 40 drops significantly. A line with the reference number 50 shows the temperature progression for a corrected volume flow at a position in the flow of the heater. It is apparent that the temperature drop is less significant here.

(12) The line with the reference number 51 represents the temperature progression which can be achieved when the heat source is arranged at the position 37. It is clearly visible that the position 39 for the arrangement of the redundant heat source 42 upstream of the external heat exchanger 16 leads to the best results for the air temperature at the heater 40.

(13) The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are to be included within the scope of the following claims.