DE102011109506B4 - Refrigerant circulation - Google Patents

Abstract

Refrigerant circuit (10) for cooling operation and heat pump operation, wherein the refrigerant circuit (10) has a high-pressure and a low-pressure region, comprising - at least one heat source / sink (26, 38), - a compressor (12), - an expansion element (18) - at least one thermal inner module (16, 34), - an inner heat exchanger (20, 30) having a high pressure side part (20) and a low pressure side part (30), the high pressure side part (20) of the inner heat exchanger operating in heat pump mode between the expansion member (18) and the heat source (26, 38), and at least one means (22, 36, 40, 42), with which the high pressure side portion (20) of the internal heat exchanger in heat pump operation at a medium pressure level (MD) is operable, wherein the medium pressure level (MD) between the pressure level in the high pressure region (HD) and the low pressure region (ND), wherein the means (22, 36, 40, 42) between the high pressure side part de s inner heat exchanger (20) and operated in the heat pump operation as a heat source heat source / sink (26, 38) is characterized in that as a heat source / sink (26, 38) a condenser / gas cooler (26) and a heat exchanger (38 ) are provided, wherein the heat exchanger (38) is integrated either in parallel or in series with the gas cooler (26).

Description

The invention relates to a refrigerant circuit for air conditioning of vehicles, according to the preamble of claim 1, and a method for operating an air conditioner according to the preamble of claim 9.

The DE 103 09 779 A1 discloses a dual-circuit air conditioner in which the refrigerant is heated in a heat pump operation either by the compression of the refrigerant and to a condenser in the interior module (hereinafter referred to as heating register) for heating the Innenraumzuluft emits. In addition, heat can be withdrawn from a coolant circuit of the engine and either supplied to the refrigerant via a heat exchanger or, in a conventional heating operation, the interior supply air can be heated via a heating core through which the coolant flows. In cooling mode, the interior air supply is deprived of heat from the condenser, which operates as an evaporator in this operating state. The heat given off to the refrigerant is then released to the environment via another condenser.

The DE 101 58 104 B4 discloses an air conditioner having a refrigerant circuit in which, in the heat pumping process, heat discharged on the high pressure side through a condenser (see explanation page 1, heating register) for heating the indoor air supply from an evaporator operating as a gas cooler in the cooling operation Ambient air is withdrawn.

In a known manner, has a refrigerant circuit, which is suitable for both the cooling and the heat pump operation, a high and a low pressure area. Such a refrigerant circuit comprises at least one heat source / sink, for example a gas cooler or condenser and / or a glycol heat exchanger, a compressor, an expansion module, at least one thermal interior module (evaporator / condenser = heating register), and a refrigerant storage.

In addition, an internal heat exchanger is provided, which has a high-pressure-side part and a low-pressure-side part, wherein the high-pressure-side part of the inner heat exchanger is in heat pump operation between the expansion module and the gas cooler. The low-pressure side part of the inner heat exchanger is arranged on the suction side to the compressor.

A refrigerant circuit of the type mentioned is for example from the JP 2009 - 270 822 A known. In this refrigerant circuit, in addition to an internal heat exchanger, an electric heating element is additionally provided in order to heat the refrigerant to the compressor on the suction side.

Other refrigerant circuits with internal heat exchanger, for example, from JP 2004 - 85 176 A or the DE 101 26 257 A1 known.

It is inter alia an object of the invention to provide the simplest possible design in order to ensure active operation of the internal heat exchanger even in heat pump operation. A further object is to appropriately store the refrigerant which is not required in the various operating states during cooling or heating operation and thus optimally adjust the circulating refrigerant.

One way to ensure the active operation of the internal heat exchanger is the relaxation of the refrigerant after the internal heat exchanger. However, this in turn has the disadvantage that the refrigerant storage device connected downstream of the inner heat exchanger in the heat pump mode is likewise subjected to high-pressure refrigerant. However, especially in the heat pump mode, the memory is too large due to the density of the refrigerant. A sufficient pressure build-up on the high pressure side can not be guaranteed.

To solve the above object, a refrigerant circuit according to claim 1 is proposed. Furthermore, a method for operating an air conditioning system with such a refrigerant circuit is proposed according to claim 9.

In this case, the refrigerant circuit comprises means by which the high-pressure-side part of the inner heat exchanger is operated in heat pump mode at a medium-pressure level which lies between the high and low pressure levels of the refrigerant circuit.

Due to the pressure loss from the high-pressure side part of the inner heat exchanger to the heat source, a pressure level of the relaxed two-phase refrigerant there, which is higher than that of the downstream heat source. In the extreme case, the range of the medium-pressure level can be exceeded or fallen below in this way and correspond to the high-pressure or low-pressure level.

Due to the high specific heat of the two-phase refrigerant and the constant temperature, the internal heat exchanger can be actively used to overheat the refrigerant flowing through the low-pressure side part of the internal heat exchanger during heat pump operation. As a result, a safe operation of the compressor is ensured in a simple manner and a suction reliably avoided by liquid refrigerant. The configuration and function of the refrigerant circuit can be used independently of the refrigerant used. Differences may be found in the respective pressure levels for low pressure, medium pressure and high pressure levels.

In addition, the interconnection can be used independently of the drive concept of the respective vehicle, for example conventionally, hybridically, electrically, etc., and thus independently of the type of compressor.

In a first advantageous embodiment, the means for operating the high-pressure-side part of the inner heat exchanger to medium-pressure level in the form of a throttle. In the heat pump mode, the throttle is connected downstream of the high-pressure-side part of the inner heat exchanger, preferably also behind a coolant reservoir.

Furthermore, the throttle is designed such that it generates a pressure loss due to a cross-sectional constriction only in the flow direction of the refrigerant in heat pump operation. In refrigeration system operation, the maximum cross-section is available in the opposite flow direction. From the expansion valve, a medium-pressure level is set in the heat pump operation, which is relaxed by the pressure relief generated by the fixed throttle after passing through the inner heat exchanger to low pressure.

Preferably, the means for realizing the medium-pressure level can also be designed in the form of a line adaptation of the line which lies between the heat source / sink and the expansion valve. The refrigerant storage and the high-pressure side part of the inner heat exchanger are then also in this area.

The cable cross-section and the wiring or line bends must be specifically determined for each vehicle, so that no significant pressure loss occurs in the cooling mode, but in the heat pump mode for the (additional) heating operation tuned pressure loss can be achieved.

In particular, the line cross-section is less common than in the prior art, since in this way material for piping and thus costs and weight can be saved. In addition, a reduced line cross-section results in a reduction in the quantity of fillings and a reduced need for refrigerants.

Furthermore, at least one further controllable expansion element can be provided in addition to the controllable expansion element, which lies in the flow direction in heat pump operation upstream of the high-pressure-side part of the inner heat exchanger. This is arranged in the aforementioned flow direction behind the high-pressure side part of the heat exchanger and after the refrigerant storage, but before the heat source.

This controllable expansion device can relax the low pressure level medium pressure level prevailing at its entrance.

According to the invention, an additional, in particular external, heat exchanger as a further heat source / sink for the transmission of heat between the engine and the refrigerant circuit can be provided in the refrigerant circuit in addition to a condenser as heat source / sink. This external heat exchanger is designed in particular as a water-glycol heat exchanger - also called a chiller.

The additional heat exchanger is integrated into the refrigerant circuit in such a way that it is essentially parallel but also in series with the condenser.

In any case, both the line leading to the condenser and the additional heat exchanger branch off from the line coming from the high-pressure-side part of the internal heat exchanger.

In a particularly advantageous embodiment, the two branches can be integrated into the process via a controllable expansion element. On the one hand can be determined by controlling the expansion organs by external control unit, whether and how the refrigerant flow flows, whereby switching valves are replaced. On the other hand, the controllable setting of the medium-pressure level in the internal heat exchanger and refrigerant storage is ensured for both branches.

It can be flexibly adjusted by an arrangement of the controllable expansion elements in the heat pump operation behind the refrigerant storage, the pressure level in the refrigerant storage, and in this Verschaltungsvariante also in the inner heat exchanger, that the amount of refrigerant available in the refrigerant circuit is optimal.

Furthermore, the invention relates to a method for operating an air conditioner, comprising a refrigerant circuit as described above, wherein at least one further controllable expansion element is provided in addition to the controllable expansion element, which lies in the flow direction in heat pump operation in front of the high-pressure side part of the inner heat exchanger. This is in the aforementioned flow direction behind the high-pressure side part of the heat exchanger and after the refrigerant storage arranged, but before the heat source.

According to the expansion organs are controlled so that they are tuned in their operation.

In particular, in the heat pump mode, the expansion elements are controlled in a single operation, in which they each work individually, and the other expansion organs are fully opened.

In another application, all expansion organs can be operated in combination mode. They are opened in dependence on each other to set a desired pressure level.

Preferably, the expansion devices can also be operated in an operating mode in which combined operation and individual operation are used as needed, in particular alternately.

Further advantages, features and possible applications of the present invention will become apparent from the following description in conjunction with the embodiments illustrated in the drawings.

• 1 eine grundlegende Darstellung eines erfindungsgemäßen Kältemittelkreislaufs im Kühlbetrieb;
• 1A eine grundlegende Darstellung eines erfindungsgemäßen Kältemittelkreislaufs im Wärmepumpenbetrieb;
• 2 eine vorteilhafte Ausgestaltung mit Leitungsquerschnittanpassung und
• 3 eine vorteilhafte Ausgestaltung mit steuerbaren Expansionsorganen und Reihenverschaltung der Wärmequellen Wasser (Chiller)und Luft (Kondensator).
• 4 zeigt eine vorteilhafte Ausgestaltung mit Parallelverschaltung.

In the description, the claims, and the drawing, the terms and associated reference numerals used in the list of reference numerals below are used. In the drawing:

• 1 a basic representation of a refrigerant circuit according to the invention in the cooling operation;
• 1A a basic representation of a refrigerant circuit according to the invention in heat pump operation;
• 2 an advantageous embodiment with line cross-section adaptation and
• 3 an advantageous embodiment with controllable expansion organs and series connection of the heat sources water (chiller) and air (condenser).
• 4 shows an advantageous embodiment with parallel connection.

Identical or equivalent components are denoted by the same reference numerals in the following embodiments.

1 shows a schematic representation of a refrigerant circuit 10 a vehicle air conditioning. This embodiment of a refrigerant circuit is suitable for the cooling operation and heat pump operation, however, sketched for the cooling operation. Here, the high-pressure refrigerant flows from the compressor 12 over the three-way valve 14 through a condenser / gas cooler 26 and through the throttle 22 , 14 is preferably designed as a 3-2-way valve, but the implementation of the interconnection can also be done in the form of 2 individual controllable shut-off valves. However, the throttle is designed such that it generates a pressure loss only in heat pump operation. In cooling mode, on the other hand, it generates no or slight pressure loss, as a result of which the refrigerant stores the refrigerant 24 and the high-pressure side part of the internal heat exchanger 20 also flows through at high pressure level and only in the main expansion valve 18 is relaxed at low pressure level. By opening the shut-off valve 32 The low-pressure refrigerant flows through the evaporator 34 and then the low-pressure side part of the inner heat exchanger 30 what it is in the compressor 12 is compressed again to high pressure level. By so designed throttle 22 arise for the cooling operation no changes to the prior art.

1A shows a schematic representation of a refrigerant circuit 10 a vehicle air conditioning after 1 , in heat pump mode, starting from the compressor 12 the refrigerant via a three-way valve 14 , via a heating register 16 to a main expansion valve 18 flows. The refrigerant is located up to the main expansion valve 18 at high pressure level HD , The main expansion valve 18 relaxes the refrigerant, which is the high-pressure side part of an internal heat exchanger 20 flows through to a medium pressure level MD , In the further course is after a refrigerant storage 24 a throttle 22 provided, which in the flow direction of the heat pump operation, the refrigerant to a low pressure level ND relaxed. At this pressure level, the refrigerant flows through a working as an evaporator condenser / gas cooler 26 ,

Subsequently, the refrigerant flows due to the open shut-off valve 28 through the low-pressure side part of the inner heat exchanger 30 and then into the compressor 12 in which it is compressed again to high pressure level.

In accordance with the invention, the refrigerant which flows through the high-pressure-side part of the internal heat exchanger 20 flows, is brought to a medium pressure level, the possibility of heat transfer with the low-pressure side of the heat exchanger is created in heat pump mode. This has the advantage that this is due to the low-pressure-side part of the internal heat transfer 30 flowing refrigerant before entering the compressor 12 can be reheated or overheated.

Overheating of the refrigerant reliably prevents aspiration of liquid refrigerants. This will ensure safe operation of the compressor 12 guaranteed.

2 shows a refrigerant circuit 10 a vehicle air conditioning in heat pump mode, in this embodiment, the medium-pressure level, which is located between the main expansion valve 18 and the gas cooler 26 results, by adjusting the cable cross-section 36 is guaranteed. The cable cross-section 36 is in 2 only indicated schematically. The cable cross-section 36 is designed such that it generates a pressure loss in heat pump operation, but not in the cooling mode. This can be achieved due to the different states of the refrigerant in the two modes.

To ensure this effect, a line analysis must be determined separately for each vehicle and is particularly dependent on the wiring or the existing bends.

In a further advantageous embodiment, as in 3 is shown, the refrigerant circuit comprises 10 next to the condenser / gas cooler 26 in addition at least one chiller 38 for heat exchange with a coolant circuit, for example a vehicle engine. Other sources of heat could be the exhaust system or the different coolant circuits of a partially or fully electrified vehicle.

With this embodiment, besides the main expansion valve 18 to ensure the medium pressure level in the high pressure side part of the internal heat exchanger 20 further controllable expansion organs 40 . 42 intended. In this case, the flow can be via either the glycol heat exchanger / chiller 38 , the condenser / gas cooler 26 or both. In passage position of the controllable expansion organ 40 . 42 the medium pressure level is relaxed in the heat pump mode to low pressure to below in glycol heat exchanger / chiller 38 and / or gas cooler 26 To be able to absorb energy. In this case, the advantages of the medium-pressure level, high-pressure-side part of the inner heat exchanger can be eliminated 20 to overheat the suction side of the compressor 12 use adjacent refrigerant.

In addition, through the coordinated control of the main controllable expansion valve 18 and the other controllable expansion organs 40 . 42 the pressure level in the refrigerant reservoir 24 be adjusted so that the storage of the refrigerant is ensured at a density that ensures both an efficient heating and a safe and reliable operation of the system.

4 shows an embodiment that in its operation substantially the 3 equivalent. In contrast to 3 is a connecting line is provided, which the flow channels through the condenser / gas cooler 26 and the glycol heat exchanger / chiller 38 in heat pump operation in the flow direction behind the said organs via a shut-off valve 44 combines. This results in the possibility of parallel operation of the condenser / gas cooler 26 and glycol heat exchangers / chillers 38 , whereas in 3 the possibility of a serial operation is shown.

LIST OF REFERENCE NUMBERS

10

Refrigerant circulation

12

compressor

14

Three-two-way valve

16

heater

18

controllable main expansion organ

20

internal heat exchanger (high pressure)

22

throttle

24

Refrigerant storage

26

Condenser / gas cooler

28

shut-off valve

30

internal heat exchanger (low pressure)

32

shut-off valve

34

Evaporator

36

Wire Gauge

38

Glycol heat exchanger / chiller

40

Controllable expansion organ

42

Controllable expansion organ

44

shut-off valve

ND

Low pressure level

MD

Medium pressure level

HD

High pressure level

Claims (12)

Refrigerant circuit (10) for cooling operation and heat pump operation, wherein the refrigerant circuit (10) has a high-pressure and a low-pressure region, comprising - at least one heat source / sink (26, 38), - a compressor (12), - an expansion element (18), - at least one thermal interior module (16, 34), - an internal heat exchanger (20, 30) having a high-pressure-side part (20) and a low-pressure-side part (30), the high-pressure-side part (20) the internal heat exchanger in heat pump operation between the expansion member (18) and the heat source (26, 38), and - at least one means (22, 36, 40, 42), with which the high pressure side portion (20) of the internal heat exchanger in the heat pump operation a medium pressure level (MD) is operable, wherein the intermediate pressure level (MD) between the pressure level in the high pressure area (HD) and the low pressure area (ND), wherein the means (22, 36, 40, 42) between the high pressure side portion of the internal heat exchanger ( 20) and operated in the heat pump operation as a heat source heat source / sink (26, 38) is characterized in that as a heat source / sink (26, 38), a condenser / gas cooler (26) and a Heat exchanger (38) are provided, wherein the heat exchanger (38) is integrated either in parallel or in series with the gas cooler (26). Refrigerant circuit (10) after Claim 1 , characterized in that the high-pressure side part of the inner heat exchanger (20) in the heat pump mode, a fixed throttle (22) is connected downstream, which generates a pressure loss only in the flow direction of the heat pump operation. Refrigerant circuit (10) after Claim 1 , characterized in that in the cooling operation between the heat source / sink (26, 38) and the expansion member (18) is provided a conduit which has a reduced cross-section compared to the other conduits, whereby no appreciable pressure loss is generated in the cooling operation, but in Heat pump operation the medium pressure level (MD) is ensured. Refrigerant circuit (10) after Claim 1 , Characterized in that between the high pressure side portion of the internal heat exchanger (20) and operated in heat pump mode as a heat source heat source / sink (26, 38) at least one controllable expansion member (40, 42) is arranged. Refrigerant circuit (10) according to one of Claims 1 to 4 , characterized in that between the high-pressure side part of the inner heat exchanger (20) and gas cooler (26), a controllable expansion element (42) is provided. Refrigerant circuit (10) according to one of Claims 1 to 5 , characterized in that a refrigerant reservoir (24) is provided, which is arranged in the medium-pressure region (MD) of the refrigerant circuit. Refrigerant circuit according to one of Claims 1 to 6 , characterized in that shut-off valves are configured such that the operation of the refrigerant circuit in the mode of cooling is preset. Refrigerant circuit according to one of Claims 1 to 7 , characterized in that the heat source / sink (26, 38) interact with the media water, air, exhaust gas, electronics, storage heat and / or solar heat / solar power. A method of operating an air conditioning system comprising a refrigerant circuit according to any one of Claims 4 to 8th , characterized in that the expansion members (18, 40, 42) are tuned in their operation. Method according to Claim 9 , characterized in that in the heat pump operation, the expansion elements (18, 40, 42) in each case operate individually, with the respective other expansion elements (18, 40, 42) are fully opened. Method according to Claim 9 , characterized in that all the expansion elements (18, 40, 42) are opened in combination operation, in dependence on each other. Method according to one of Claims 9 to 11 , characterized in that a combination operation and a single operation are used as needed alternately.

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