Refrigerant circuits- of said type are known from the prior art. The refrigerant is typically present in a vaporous state before it is conducted into the evaporator. This means that the refrigerant is partially liquid and partially gaseous. The problem now consists in distributing the refrigerant uniformly among the evaporation ducts arranged in parallel. In the prior art, for this purpose, use is made of a guide mechanism which is of complex construction and by means of which the refrigerant flowing into the distributor of the evaporator is distributed as uniformly as possible among the evaporation ducts by means of diverting plates. However, the greater the number of evaporation ducts is, the more complex is the construction of the diverting mechanism. From the aspect of cooling, it -is however advantageous for as many evaporation ducts as possible to be arranged in parallel, because in this way the pressure loss is reduced and the active surface area of the evaporator is increased. The main problem of the refrigerant circuits known from the prior art consists in that the refrigerant is present in a partially liquid and partially gaseous form, such that pressure differences and/or volume differences arise in the evaporation ducts because the homogeneous distribution of the liquid component of the refrigerant is very difficult to ensure. Specifically, the liquid component of the refrigerant does not distribute homogeneously among the evaporation ducts because the liquid does not react as sensitively to pressure differences as a gas. The disadvantage of the refrigerant circuits known from the prior art accordingly consists in that, although the gas can react to pressure differences in the evaporation ducts arranged in parallel, the liquid component of the refrigerant does not react to the pressure differences, as a result of which a homogeneous distribution of the gaseous and liquid components of the refrigerant in the evaporation ducts arranged in parallel is not provided. This has the effect that the evaporator operates in a non-optimal manner, and there is accordingly a demand for an increase in efficiency.

It is therefore the object of the invention to provide a refrigerant circuit which has a more efficient evaporator. To achieve said object, the invention provides a refrigerant circuit, in particular for a vehicle air conditioning unit, having at least one condenser, an evaporator with a distributor, wherein the evaporator has multiple evaporation ducts arranged in parallel, and having a compressor, wherein, upstream of the evaporation ducts, there is provided a separating device for separating refrigerant fluid into a liquid component and a gaseous component, and wherein at least the liquid component passes via the distributor into the evaporation ducts.

It is the basic concept of this invention for the refrigerant to be separated into its gaseous and liquid components before it passes into the evaporation ducts. Through the separation of the gaseous and liquid components, a completely novel concept is realized whereby it is ensured that a homogeneous distribution of the refrigerant is supplied to the evaporation ducts, both with regard to the gaseous component and also with regard to the liquid component of the refrigerant. For this purpose, use is made of the separating device which separates the refrigerant, composed of a gaseous component and of a liquid component, into its gaseous and liquid components. In one embodiment of the invention, not only the liquid component but also at least a partial volume of the gaseous component passes via the distributor into the evaporation ducts. The separating device preferably has outlets which are fluidically connected directly to the evaporation ducts. In this way, the liquid component of the refrigerant can be conducted directly into the evaporation ducts of the evaporator.

In particular, at least one secondary line is provided for a fraction of the separated refrigerant, which secondary line issues into the distributor proceeding from an outlet of the separating device. Via said secondary line, it is for example possible for the gaseous component or a partial volume of the gaseous component to be supplied to the distributor, wherein the distributor can correspondingly distribute the gaseous component of the refrigerant among the evaporation ducts.

In one particularly preferred embodiment, a bypass line is provided which extends in parallel with the evaporator proceeding from an outlet of the separating device and which issues into the circuit downstream of the evaporator. The bypass line can divert at least a partial volume of the gaseous component past the evaporator. Via said bypass line, a partial volume of the gaseous component, in particular the hot gas, can be introduced into the circuit downstream of the evaporator in order to evaporate any residual amount of the liquid component of the refrigerant that may be present. This is possible owing to the superheat of the hot gas.

In particular, the separating device has at least one outlet for the liquid component and at least two outlets for the gaseous component of the refrigerant. In this way, it is possible for the separating device to separate the refrigerant into the liquid and gaseous components and to divide the gaseous component into certain partial volumes or else separate the gaseous component into a hot fraction and a cold fraction. Ά partial volume of the gaseous component may for example be used for pressure compensation in the evaporation ducts. The two outlets of the separating device for the gaseous component preferably issue into the distributor at opposite ends, preferably at axial ends of the tubular distributor. In this way, it is ensured that the distributor is charged uniformly with the gaseous component of the refrigerant, such that the gas is distributed more homogeneously in the distributor and the homogeneous distribution of the gaseous component among the evaporation ducts is simplified. In a particularly preferred embodiment, the separating device is integrated in the evaporator, preferably in the head of the evaporator or in the distributor. This leads to a particularly compact design because the separating device need not be formed as a separate component but rather is already integrated in the evaporator, whereby the feed lines to the evaporator would also be omitted. Furthermore, the invention encompasses a separating device for separating a refrigerant into a liquid component and a gaseous component for a refrigerant circuit of the above-stated type, having an inlet for a refrigerant, in particular for a vaporous refrigerant, having at least one gas outlet for the gaseous component of the refrigerant, having at least one liquid outlet for the liquid component of the refrigerant, and having a tubular separating chamber for the separation of the refrigerant, wherein the refrigerant is introduced into the separating chamber via the inlet tangentially with respect to the inner side of the shell surface of said separating chamber, and the liquid outlet is formed by at least one opening in the shell surface. Such a separating device makes it possible for the refrigerant to be separated into its liquid and gaseous components, wherein this takes place in a simple manner, preferably without moving parts. The refrigerant, which is introduced into the separating chamber tangentially with respect to the inner side of the shell surface, becomes a swirling flow in the tubular separating chamber. As a result of said swirl, the liquid component is separated from the gaseous component of the refrigerant and is forced against the inner side of the separating chamber owing to the centrifugal forces. The liquid outlet for the liquid component of the refrigerant is provided on the inner side of the separating chamber, such that the liquid component can exit the separating chamber. The gaseous component continues to pass through the separating chamber in a swirling manner as far as the axial end of the tubular separating chamber. At least a fraction of the gas exits the separating chamber via the gas outlet. The separating device according to the invention may be used in an evaporator or else in a condenser that can be operated in the reverse direction, which condenser then operates as an evaporator.

In particular, the separating device for gas and liquid has integrated therein a gas separating device which separates hot and cold gas.

It is preferable for two axially opposite gas outlets to be provided. This has the advantage that the gaseous component can exit the separating chamber on both sides, whereby a more homogeneous distribution of the gas flow can be ensured.

In particular, at one axial end of the separating chamber, there is provided an in particular central diverting element, proceeding from which gas, in particular cold gas, is diverted in the direction of the opposite axial end. Here, use is made of the fact that the swirling gas in the tubular separating chamber is divided into a cold flow and a hot flow owing to the high centrifugal forces. Here, the cold flow of the gaseous component runs at the inside of the swirl, whereas the hot fraction of the gaseous component of the refrigerant runs at the outer edge of the swirl, that is to say in the vicinity of the inner wall of the separating chamber. By virtue of the fact that a diverting element is provided centrally at one axial end of the separating chamber, the cold gas impinges on said diverting element and is diverted or reflected at said diverting element.

In particular, at least one gas outlet for hot gas is provided between the diverting element and the shell surface. The hot gas, which runs at the outer edge of the swirl in the swirling flow of the gaseous component, can accordingly exit the separating chamber at the axial end by exiting the separating chamber via a gas outlet between the diverting element and the shell surface.

In a particularly preferred embodiment, at least one liquid reservoir is provided for the liquid component of the refrigerant, which liquid reservoir collects the liquid component of the refrigerant that emerges through the liquid outlet. The liquid reservoir serves for collecting the liquid component of the refrigerant in order to distribute said liquid component more uniformly among the evaporation ducts of the evaporator .

In particular, the shell surface has numerous liquid outlets distributed along its length. This has the advantage that the liquid component of the refrigerant can exit the separating chamber where said liquid component impinges on the shell surface. The liquid accordingly need not run along the shell surface in order to arrive at a single liquid outlet.

In particular, the liquid outlets issue into at least one liquid reservoir. In this way, it is ensured that the entire liquid component of the refrigerant is collected in a liquid reservoir, from which the liquid can be distributed homogeneously among the evaporation ducts when the liquid reservoir is filled.

It is preferable for at least one guide element to be provided, by means of which the liquid emerging from the liquid outlet is guided into the evaporation ducts. By means of the guide element, it is ensured that the entire liquid component of the refrigerant passes into the evaporation ducts, regardless of the installation situation of the separating device.

Furthermore, according to the invention, there is provided an evaporator for a refrigerant circuit of the above-stated type, having a distributor and having multiple evaporation ducts arranged in parallel, wherein a separating device is provided for separating a refrigerant into a liquid component and a gaseous component. According to the invention, provision is accordingly made for the separating device to be integrated directly into the evaporator, thus making a compact construction possible. In particular, the separating device is designed as described above. In this way, the advantages mentioned above are likewise realized in the evaporator according to the invention. The liquid outlets on the shell surface are preferably connected directly to the evaporation ducts arranged in parallel. This constitutes a particularly space-saving and compact evaporator with a separating device, because the liquid component of the refrigerant can pass directly into the evaporation ducts.

In a particularly preferred embodiment, the distributor has a distributor chamber which surrounds the separating chamber, wherein the liquid outlets in the shell surface of the separating chamber issue into the distributor chamber. This offers the advantage that the liquid component of the refrigerant can be distributed homogeneously among the evaporation ducts by means of the distributor, whereby the efficiency of the evaporator is increased.

In particular, the distributor chamber has an uneven cross section with a wide portion, into which separated-off gas flows, and a relatively narrow portion, in which there is provided a transition to the evaporation ducts, in particular with the interposition of the liquid reservoir. This has the advantage that the refrigerant gas flowing out of the separating chamber is distributed homogeneously among the evaporation ducts via the distributor chamber, and the liquid component can be temporarily stored or collected in the liquid reservoir in order to then be supplied homogeneously to the evaporation ducts. The parallel ducts can accordingly be supplied with homogeneous fractions of gaseous component and liquid component. The evaporator according to the invention may also be a combined evaporator-condenser which, when operated in one flow direction, acts as a condenser and which, when operated in the opposite flow direction, acts as an evaporator .

Further features and advantages of the invention will emerge from the following description and from the subsequent drawings, to which reference is made and in which : - Figure 1 is a schematic illustration of the refrigerant circuit according to the invention, as per a first embodiment.

Figure 2 is a schematic illustration of the refrigerant circuit according to the invention as per a second embodiment,

Figure 3 shows a partial sectional view of an evaporator according to the invention in the region of the separating device according to the invention, as per a first embodiment,

- Figure 4 shows a partial sectional view of an evaporator according to the invention in the region of the separating device according to the invention, as per a second embodiment, - Figure 5 shows a perspective view of the separating device according to the invention,

- Figure 6 shows a perspective sectional view of the evaporator in the region of the separating device according to the invention,

- Figure 7 shows a perspective view of an axial end of the separating device according to the invention,

- Figure 8 shows the axial end of the separating device from figure 7, without a cover,

- Figure 9 shows the other axial end of the separating device according to the invention in relation to figure

8,

- Figure 10 shows the axial end of the separating device from figure 9, with diverting element,

- Figure 11 shows a partial sectional view through the evaporator according to the invention in the region of the separating device according to the invention, - Figure 12 shows a partial sectional view of the evaporator according to figure 11 in the region of the separating device according to the invention along its longitudinal axis, - Figure 13 shows an enlarged perspective view of the transition region in the separating device to the liquid reservoir, and

- Figure 14 shows a perspective view of the region shown in figure 13, from a different perspective.

Figure 1 shows a refrigerant circuit 10 of a vehicle air conditioning unit, which refrigerant circuit has a separating device 12, a compressor 14, a condenser 16, an expansion device 18 and an evaporator 20. A refrigerant 22 flows through the components and the lines that connect the abovementioned components of the refrigerant circuit 10 to one another. The refrigerant 22 is present in a gaseous state in the compressor 14. The compressor 14 compresses the refrigerant 22, whereby the already gaseous refrigerant 22 undergoes intense heating. The now heated refrigerant 22 passes to the condenser 16, in which said refrigerant condenses and thus becomes, for the most part, liquid. In this embodiment, the refrigerant 22 is conveyed from the condenser 16 to the separating device 12, which separates the refrigerant 22 into a gaseous component 24 and a liquid component 26. The gaseous component 24 of the refrigerant 22 can be supplied via a secondary line 28 directly to the evaporator 20, whereas the liquid component 26 optionally passes initially through the expansion device 18. In the expansion device 18, the virtually boiling liquid 26 is expanded, whereby the liquid component 26 expands and is cooled. After passing through the expansion device 18, the liquid component 26 is (likewise) supplied to the evaporator 20. In the evaporator 20, the liquid component 26 is evaporated, whereby an evaporative cooling action is generated which can be used for cooling purposes, for example for cooling a vehicle interior.

After passing through the evaporator 20, the now practically completely evaporated refrigerant 22 passes to the compressor 14 again, and the circuit begins again.

Figure 2 shows an alternative embodiment of the refrigerant circuit 10, wherein the same components are illustrated. In this embodiment, the optional expansion device 18 is arranged upstream of the separating device 12. Furthermore, a bypass line 30 extends from the separating device 12, which bypass line runs parallel to the evaporator 20 and issues into the circuit again downstream of the evaporator 20. The bypass line 30 is provided for refrigerant circuits 10 with a separating device 12 which not only divides the refrigerant 22 into a gaseous component 24 and a liquid component 26 but also divides the gaseous component 24 into a hot fraction of the gas 32 and a cold fraction of the gas 34. The hot gas 32 separated in the separating device 12 is conducted past the evaporator 20 via the bypass line 30 and is first reintroduced into the circuit downstream of the evaporator 20. The idea behind this is that the hot gas 32 exhibits superheat which can be utilized to evaporate a liquid component 26 that may possibly remain after passing through the evaporator 20. In this way, the refrigerant 22 is supplied only in gaseous form to the compressor 14. Liquid components 26 of the refrigerant 22 in the compressor 14 would have an adverse effect on the service life of the compressor 14, for which reason the bypass line 30 is to be regarded as an additional safety element for the compressor 14.

Alternatively, the entire gaseous component 24 may also be conducted past the evaporator 20 via the bypass line 30, such that only the liquid component 26 is supplied to the evaporator 20. It is thus possible for the efficiency of the evaporator 20 to be improved, because the pressure within the evaporator 20 can be controlled by means of the bypass line 30 and the gaseous component 24 supplied. It is preferably also provided that the separating device 12 is integrated in the evaporator 20.

Furthermore, the expansion device 18 may optionally be combined with the separating device 12. The exact mode of operation of the separating device 12 for the division of the refrigerant 22 into a gaseous component 24 and a liquid component 26, and in particular the separation of the gaseous component 24 into hot gas 32 and cold gas 34, will be explained on the basis of the subsequent figures.

Figure 3 shows a sectional view of an evaporator 20 according to the invention in the region of its head, which comprises the separating device 12 and a distributor 35, wherein the separating device 12 is arranged in the distributor 35 of the evaporator 20. The separating device 12 has a separating chamber 36 which is preferably of tubular form. The separating chamber 36 has a shell surface 38 which closes off the separating chamber 36 to the outside. Furthermore, the separating chamber 36 has an inlet 40 close to a first axial end of the separating chamber 36, through which inlet the refrigerant 22 is introduced into the separating chamber 36 tangentially with respect to the shell surface 38. The separating chamber 36 has, at the opposite axial end, a gas outlet 42 through which the gaseous component 24 of the refrigerant 22 separated by the separating device 12 can exit the separating chamber 36. In the embodiment shown, the gaseous component 24 can exit the separating chamber 36 via the gas outlet 42 into a distributor chamber 44 of the distributor 35.

From the distributor chamber 44, the gaseous component 24 or a partial volume of the gaseous component 24 can be conducted in homogeneous form to numerous, in particular flat evaporation ducts 46 which are arranged adjacent one another. Alternatively, the gaseous component 24 may exit the distributor chamber 44 via the gas outlet line 28 ' . The ducts 46 are only partially illustrated here. The liquid component 26 of the refrigerant 22 collects on the shell surface 38 of the separating chamber 36, because the refrigerant 22 is introduced through the inlet 40 such that a swirling flow is formed, and the more dense liquid component 26 is forced against the inner side of the separating chamber 36, that is to say against the shell surface 38. The shell surface 38 has, over its longitudinal extent, liquid outlets 48 which enable the liquid component 26 to exit the separating chamber 36. Arranged so as to directly adjoin the liquid outlets 48 is a liquid reservoir 50 which, in this embodiment, is formed as part of the distributor chamber 44. The liquid reservoir 50 collects the liquid component 26, emerging through the liquid outlets 48, of the refrigerant 22 and distributes said liquid component homogeneously among the evaporation ducts 46. Thus, figure 3 shows a separating device 12 which separates the refrigerant 22 into a liquid component 26 and a gaseous component 24 and which is furthermore integrated in the evaporator 20.

Figure 4 shows a second embodiment of the evaporator 20, wherein said evaporator 20 differs from the evaporator 20 of the first embodiment in that the separating device 12 has two oppositely directed gas outlets 42.

At the first axial end of the separating device 12, at which the inlet 40 is also arranged, there is provided a second gas outlet 42 which, in the embodiment shown here, is connected in terms of flow to the distributor chamber 44.

Furthermore, a diverting element 52 is arranged in the separating chamber 36 of the separating device 12. Here, the diverting element 52 is preferably arranged at the second axial end, which is situated opposite the inlet 40, of the separating chamber 36. The diverting element 52 is in particular of conical design.

As already described above, the refrigerant 22 is introduced into the separating chamber 36 tangentially through the inlet 40, whereby a swirling flow forms. Here, firstly, the liquid component 26 is separated from the gaseous component 24 such that the liquid component 26 collects on the inner side of the separating chamber 36, preferably of the shell surface 38, in order to exit the separating chamber 36 through the liquid outlets 48. Here, the liquid component 26 is collected by the liquid reservoir 50 and, from there, is distributed homogeneously among the evaporation ducts 46. The gaseous component 24 of the refrigerant 22, which gaseous component swirls through the separating chamber 36, is caused by the swirling motion to take on a form in which the relatively cold gas 34 collects at the inside of the swirl, whereas the hot gas 32 is present in the outer region of the swirl. The swirling gaseous component 24 now moves from the first axial end, at which the inlet 40 is provided, to the opposite, second axial end of the separating chamber 36.

Provided at the second axial end is the diverting element 52, on which the gaseous component 24 impinges. Owing to the conical design of the diverting element 52, the hot gas 32 can exit the separating chamber 36 through the gas outlet 42 which is provided between the shell surface 38 and the diverting element 52. By contrast, the cold gas 34 which is arranged at the inside of the swirl impinges on the diverting element 52 and is diverted by the latter such that the cold gas 34 passes along the separating chamber 36 to the first axial end at which the inlet 40 is arranged. Provided at said axial end is the second gas outlet 42, through which the cold gas 34 can exit the separating chamber 36 and is conducted into the distributor chamber 44.

In the embodiment shown, both gas outlets 42 are connected to the distributor chamber 44 and issue into the distributor chamber 44 at axially opposite ends. It may also be provided that the first gas outlet 42 for the hot gas 32 does not issue into the distributor chamber 44, but rather, as per the refrigerant circuit 10 described in figure 2, is conducted past the evaporator 20 via a bypass line 30 which proceeds from the outlet 42 for hot gas 32. In this way, the hot gas 32 is not conducted into the evaporation ducts 46 but rather is first fed in again downstream of the evaporator 20. The hot gas 32 exhibits superheat owing to its high temperature, which superheat can be utilized downstream of the evaporator 20 to evaporate a liquid component 26 that remains after passing through the evaporation ducts 46.

Figure 5 shows the separating device 12, without evaporation ducts 46, from the outside, wherein it is possible to see the inlet 40 for the refrigerant 22 and the housing of the distributor chamber 44. The axial ends of the separating device 12 have flanges 53 by which they can be fastened. Furthermore, in figure 5, it is possible to see into the separating chamber 36 through one axial end, wherein two liquid outlets 48 are visible. Figure 6 shows the separating device 12 together with distributor 35 in a sectional perspective view, wherein the evaporator 20 has been rotated through 180° in relation to figure 5, because in this figure the inlet 40 for the refrigerant 22 is illustrated on the right- hand side. The figure shows the known features of the evaporator 20 from figure 4, wherein this figure shows fin-like guide elements 54 which are arranged downstream of the liquid outlets 48 and which guide the liquid component 26 of the refrigerant 22 into the evaporation ducts 46 (of which only the inlet is shown here) if the evaporator 20 is installed in an upright position rotated through 90° in relation to the horizontal position shown. The liquid component 26 exits the separating chamber 36 of the separating device 12 through the liquid outlets 48 and, in so doing, impinges on the guide elements 54. The liquid component 26 runs along said guide elements 54 and ultimately passes into the evaporation ducts 46.

If the separating device 12 is installed in a horizontal position, the guide elements 54 do not perform a guiding function for the liquid component 26 of the refrigerant 22. The separating device 12 illustrated in figure 6 is the embodiment that has also been shown in figure 4, because the separating device 12 has two gas outlets 42 for the hot gas 32 and for the cold gas 34. The gaseous component 24 formed by the hot gas 32 and the cold gas 34 is conducted into the distributor chamber 44, from where the gaseous component 24 can optionally be conducted past the evaporation ducts 46 via the gas outlet line 28' or passes directly into the evaporation ducts 46. Figure 7 shows that axial end of the evaporator 20 at which the inlet 40 of the separating device 12 is arranged. Shown on said axial end is the gas outlet line 28' which extends through a cover 58 which sealingly closes off the axial end of the evaporator 20.

Figure 8 shows the axial end from figure 7 without the cover 58, whereby it is possible to see laterally into the distributor chamber 44 and into the separating chamber 36.

Figure 9 shows the opposite axial end of the evaporator 20, wherein no cover is illustrated, such that it is possible to see laterally into the separating chamber 36 and into the distributor chamber 44 from the other axial side of the separating device 12. In the illustration shown here, the diverting element 52 is not installed, wherein a mounting part 60 for the diverting element 52 is however shown.

Figure 10 shows the axial end of the evaporator 20 from figure 9 with the diverting element 52 installed, said diverting element being held by the mounting part 60 such that the gas outlet 42 is realized between the shell surface 38 and the diverting element 52. The hot gas 32 can exit the separating chamber 36 and flow into the distributor chamber 44 through said gas outlet 42.

Figure 11 shows a sectional view of the evaporator 20, illustrating the arrangement of the separating device 12 with the separating chamber 36 within the distributor chamber 44. It is also clear from the figure how the liquid component 26 of the refrigerant 22 can exit the separating chamber 36 through the liquid outlets 48 and flow into the liquid reservoir 50 arranged in the distributor chamber 44. From said liquid reservoir 50, the liquid component 26 of the refrigerant 22 flows into the evaporation ducts 46.

It is also possible from said figure to see the geometric dimensions of the separating chamber 36 and of the distributor chamber 44 relative to one another, wherein it is clear that the distributor chamber 44 has an uneven cross section, because it has a wide portion, into which the gaseous component 24 flows, and a relatively narrow portion, in which the liquid reservoir 50 is arranged.

Figure 12 shows a sectional view along the longitudinal axis of the evaporator 20. It can be seen from the figure how the guide elements 54 guide the liquid component 26 into the evaporation ducts 46 if the separating device 12 is installed in a vertical arrangement. The liquid component 26 passes out of the separating chamber 36 through the liquid outlets 48 and impinges on the guide elements 54. The liquid component 26 is guided by said guide elements 54 such that the liquid component 26 can enter the evaporation ducts 46.

Figures 13 and 14 are perspective views of figure 12, wherein it is the intention to illustrate the mode of operation of the guide elements 54 and the interaction with the liquid outlets 48. The separating chamber 36 has the liquid outlets 48 through which the liquid component 26 exits the separating chamber 36. Here, the liquid component 26 flows into the trough-shaped liquid reservoir 50, from where the liquid component 26 passes to the evaporation ducts 46 when the respective reservoir 50 is full. In the case of a construction rotated through 90°, the guide elements 54 would have the effect that the liquid component 26 runs along the guide elements 54 and passes into the liquid reservoir 50 or directly into the evaporation ducts 46. Provision is thus made of a refrigerant circuit 10, a separating device 12 and in particular an evaporator 20 with integrated separating device 12, which make it possible for the evaporator 20 to be operated efficiently or for the efficiency of the evaporator 20 to be increased by virtue of the refrigerant 22 being separated into a gaseous component 24 and a liquid component 26 before it enters the evaporation ducts 46.