Refrigerant circuit with a low-pressure refrigerant storage tank for vapor content stabilization and motor vehicle

Abstract

The invention relates to a refrigerant circuit for a motor vehicle, comprising a refrigerant storage tank (10) arranged downstream of an evaporator of the refrigerant circuit and upstream of a compressor of the refrigerant circuit. The refrigerant storage tank (10) has an inlet pipe (26) with a discharge opening (28) through which the refrigerant coming from the evaporator can be introduced into a receiving chamber (30) of the refrigerant storage tank (10). The refrigerant storage tank (10) has a suction device (34) with an intake opening (36). Gaseous refrigerant from the receiving chamber (30) can be introduced into the suction device (34) via the intake opening (36). The refrigerant storage tank (10) has at least one filter element (70) which is permeable to the gaseous refrigerant and which is designed to retain liquid refrigerant (48).The extraction device (34) is protected from the ingress of liquid refrigerant (48) into the extraction device (34) via the intake opening (36) by at least one filter element (70). Furthermore, the invention relates to a motor vehicle with the refrigerant circuit.

Description

The invention relates to a refrigerant circuit for a motor vehicle, having a refrigerant accumulator which is arranged downstream of an evaporator of the refrigerant circuit and upstream of a compressor of the refrigerant circuit. The refrigerant accumulator has an inlet pipe with a discharge opening. Via the discharge opening, the refrigerant coming from the evaporator can be introduced into a receiving space of the refrigerant reservoir. The refrigerant accumulator has a suction device with a suction opening. Gaseous refrigerant originating from the receiving space can be introduced into the suction device via the suction opening. The invention furthermore relates to a motor vehicle having such a refrigerant circuit.A refrigerant accumulator, which is arranged downstream of the evaporator and upstream of the compressor as seen in the flow direction of the refrigerant through the refrigerant circuit, is also referred to as a low-pressure refrigerant accumulator. Depending on the quantity of refrigerant circulating in the refrigerant circuit, a level of liquid refrigerant in the refrigerant accumulator may vary.During operation of the refrigerant circuit, it is desirable if the refrigerant extracted from the receiving space of the refrigerant accumulator via the extraction device is predominantly gaseous. However, a certain proportion of liquid refrigerant in the two-phase mixture, which is supplied to the compressor from the refrigerant accumulator during operation of the refrigerant circuit, is expedient. This is because, on the one hand, cooling of the compressor can be effected by means of the liquid refrigerant fraction in the mixture. Secondly, liquid refrigerant is better suited to binding lubricating oil or, owing to a better solubility of lubricating oil in liquid fractions of refrigerant, to return the lubricating oil originating from the compressor and circulating in the system or in the refrigerant circuit back into the compressor. This is advantageous for ensuring a long-lasting operability of the compressor.On the other hand, it is disadvantageous if the mixture extracted from the refrigerant accumulator via the extraction device contains a comparatively large amount of liquid refrigerant and, accordingly, little gaseous refrigerant. This is because, with a constant mass flow of refrigerant conveyed by means of the compressor, a cooling capacity of the evaporator is thereby reduced. Namely, a difference in enthalpy of the refrigerant at the entrance to the evaporator and at the exit from the evaporator is smaller as the proportion of liquid refrigerant supplied to the compressor from the refrigerant accumulator increases. Such an enthalpy loss can be compensated for by increasing the mass flow of refrigerant conveyed by the compressor, but at the expense of system efficiency due to increased drive power consumption at the compressor.In particular, if the refrigerant circuit does not have an internal heat exchanger, in which a heat emission of the refrigerant compressed by means of the compressor to the expanded refrigerant supplied to the compressor takes place internally to the system, an increased suction of liquid refrigerant through the compressor can occur depending on the fill level of the liquid refrigerant in the refrigerant accumulator. This causes the unfavourable case of wet suction of refrigerant by the compressor and possibly even wet compression. This operating case can have a negative effect on bearing strengths due to a wash-out of lubricating oil, but also likewise disadvantageous effect on the mode of action of an oil separator of the compressor.DE 10 2009 020 844 A1 describes an accumulator for a motor vehicle air conditioning system comprising a housing with an inlet and an outlet for a refrigerant, a tube connected to the outlet and extending into the housing, and means for generating a swirling flow in the interior of the housing. In the housing, a hollow cylinder closed at the bottom is located. The tube is guided in the longitudinal axis direction of the cylinder as far as beyond the open cylinder side into an upper housing region. The upper end of the pipe guided through the cylinder has a membrane which is only or predominantly permeable to gaseous refrigerant.DE 103 55 496 A1 describes a hydraulic accumulator for a motor vehicle air conditioning system. A fluid inlet pipe assembly of the hydraulic accumulator includes a diverter portion configured to direct refrigerant flowing through a first portion of the fluid inlet pipe assembly on side walls and downwardly away from a top of an accumulator housing of the accumulator. This is intended to prevent turbulence from occurring in the hydraulic accumulator.Further refrigerant accumulators incorporated into a respective refrigerant circuit are described, for example, in EP 3 550 223 A1 and in U.S. Pat. No. 4,651,540 A.It is an object of the present invention to provide a refrigerant circuit of the type mentioned at the beginning, in which a vapor content of the refrigerant extracted from the refrigerant accumulator is particularly insensitive to different filling levels of refrigerant in the receiving space of the refrigerant accumulator, and to specify a motor vehicle having such a refrigerant circuit.This object is achieved by a refrigerant circuit having the features of claim 1 and by a motor vehicle having the features of claim 9. Advantageous embodiments with expedient developments of the invention are specified in the dependent patent claims and in the following description.The refrigerant circuit for a motor vehicle according to the invention comprises a refrigerant accumulator which is arranged downstream of an evaporator of the refrigerant circuit and upstream of a compressor of the refrigerant circuit. The refrigerant accumulator has an inlet pipe with a discharge opening. Via the discharge opening, the refrigerant coming from the evaporator can be introduced into a receiving space of the refrigerant reservoir. Furthermore, the refrigerant accumulator has a suction device with a suction opening. Gaseous refrigerant originating from the receiving space can be introduced into the suction device via the suction opening. The refrigerant reservoir has at least one filter element, which is permeable to the gaseous refrigerant and which is designed to retain liquid refrigerant. The suction device is protected by the at least one filter element from penetration of liquid refrigerant into the suction device via the suction opening.The at least one filter element is formed by a wall material of a bag arranged in the receiving space, wherein the bag contains a desiccant. This is particularly advantageous since a dryer unit is arranged in the receiving space of the refrigerant reservoir by the bag containing the desiccant. The dryer unit advantageously ensures during operation of the refrigerant circuit a removal of potential water components or moisture from the refrigerant or from the interior of the system or refrigerant circuit.By using the wall material of the pouch as the at least one filter element, the at least one filter element can be provided with particularly low outlay. In addition, this makes use of the fact that the wall material of the bag has a nature which brings about the permeability for the gaseous refrigerant and the ability to retain liquid refrigerant.In the refrigerant circuit according to the invention, the at least one filter element is represented or functionally provided by a partial region of the bag free of the desiccant, which filter element rests on the suction opening of the suction device. Accordingly, when filling the bag with the desiccant, for example in the form of granules, it can be ensured that the bag is not filled in an impact manner, but that the partial region of the bag remains free of the desiccant. This empty partial region of the bag can be used particularly well as a filter element.In this way, it is also prevented that the refrigerant, which passes through the wall material of the bag via the suction opening into the suction device, has to flow around the desiccant or around the particularly granulate-like particles of the desiccant. As a result, the drying agent does not ensure an increase in the flow resistance during the extraction of the refrigerant from the refrigerant reservoir via the extraction device. This is advantageous.Accordingly, the at least one filter element ensures that during operation of the refrigerant circuit no or virtually no liquid refrigerant can enter or enter the suction device via the suction opening. This is because the at least one filter element retains the liquid refrigerant and, on the other hand, allows the gaseous refrigerant to pass through. This ensures that liquid refrigerant does not pass undefined into the suction device. This in turn leads to a desired vapor content, i.e. a desired fraction of gaseous refrigerant in a two-phase mixture, which is extracted from the refrigerant accumulator via the extraction device during operation of the refrigerant circuit, and which contains gaseous refrigerant with a certain fraction of liquid refrigerant, being adjustable very well and in a well reproducible manner.The vapor content of the two-phase mixture is understood in the present case to mean the gaseous fraction of refrigerant in the two-phase mixture. Thus, at a vapor content of 0% only liquid refrigerant is present and at a vapor content of 100% only gaseous refrigerant is present.The suction device preferably has an inlet for liquid refrigerant or a liquid refrigerant-oil mixture, which is arranged during operation of the refrigerant circuit below a liquid level of liquid refrigerant or refrigerant-oil mixture, which is located in the receiving space of the refrigerant reservoir. Via this inlet, a defined amount of liquid refrigerant can be added or mixed with the gaseous refrigerant. This amount can be adjusted very easily by presetting the size of the inlet. The suction device thus preferably has at least two suction sections spaced apart from one another, of which the first section is designed as the suction opening and brings about the introduction of the gaseous refrigerant, and of which the second section is designed as the inlet and brings about the admixture of the liquid refrigerant or refrigerant-oil mixture.By adding a certain proportion of liquid refrigerant to the gaseous refrigerant, which reaches the suction device via the suction opening, a two-phase refrigerant state is established. This is advantageous for several reasons. Firstly, by supplying the compressor with the two-phase mixture which contains gaseous and liquid refrigerant, the compressor can be cooled during operation. In addition, a lubricant, such as a lubricating oil or the like, can be returned to the compressor particularly effectively via the liquid refrigerant fraction in the two-phase mixture, wherein the lubricant lubricates movable parts of the compressor.However, since the at least one filter element ensures at least largely the suction of the refrigerant present in gaseous or gaseous phase and thus prevents liquid refrigerant from entering the suction device via the suction opening, uncontrolled entry of liquid refrigerant into the suction device is avoided. This in turn leads to the situation that, for example, even in the case of a high filling level of refrigerant in the receiving space of the refrigerant accumulator, the two-phase mixture of gaseous refrigerant and liquid refrigerant, which mixture is extracted from the refrigerant accumulator via the extraction device, has the desired vapor content.Accordingly, by providing the at least one filter element which protects the suction device from the penetration or entry of liquid refrigerant fractions into the suction device via the suction opening, the vapor content of the refrigerant extracted from the refrigerant reservoir can be adjusted particularly well. Consequently, in the refrigerant circuit, the vapor content of the refrigerant extracted from the refrigerant accumulator is particularly insensitive to different filling levels of refrigerant in the receiving space of the refrigerant accumulator.In particular, it can be achieved in this way that over a very large range of different masses stored in the cold accumulator and also different mass flows of refrigerant, which circulate in the refrigerant circuit during operation thereof, the vapor content of the two-phase mixture of gaseous refrigerant and liquid refrigerant extracted from the refrigerant accumulator is substantially constant. Accordingly, this vapor content is substantially constant even at different filling levels of refrigerant in the receiving space of the refrigerant accumulator. This is advantageous. The performance of an air conditioning system and / or heat pump comprising the refrigerant circuit is thus particularly good and particularly stable.In addition, it is thereby avoidable that an undesired washing out of oil or similar lubricant from the compressor or refrigerant compressor occurs during operation of the refrigerant circuit. This applies in particular to sections of the compressor which have a lubrication requirement which is satisfactory by a lubricant. In contrast, a wash-out of lubricant from the compressor can be more easily carried out if the proportion of liquid refrigerant in the two-phase mixture, which the compressor draws in during operation of the refrigerant circuit, is too high.In addition, an increase in the performance, in particular of the evaporator of the refrigerant circuit, can be achieved in an advantageous manner by increasing the mass flow of refrigerant conveyed by the refrigerant compressor during operation of the refrigerant circuit, without this leading to appreciable fluctuations in the vapor content in the two-phase mixture leaving the refrigerant accumulator. The two-phase mixture, which comprises gaseous and liquid refrigerant, generally additionally contains oil or a lubricant of this type, which is fed back together with the mixture into the compressor or refrigerant compressor in order to lubricate the compressor. Therefore, when the term two-phase mixture is used herein, this term also applies to this refrigerant mixture containing oil or the like lubricant, which sucks into the compressor.Furthermore, this allows operation of a system which comprises the refrigerant circuit to be particularly stable in terms of thermodynamic and regulation technology.It is particularly advantageous if the at least one filter element is only permeable for the gaseous refrigerant and is designed for at least nearly complete retention of the liquid refrigerant fraction. This is because it is particularly securely avoidable that liquid refrigerant enters a first section of the suction device via the suction opening. This applies in particular if this property of the at least one filter element exists permanently and in all operating states of the refrigerant circuit, as is preferably the case in the present case.The at least one filter element preferably comprises a shielding device which is arranged in the receiving space of the refrigerant accumulator at a distance from the suction opening. By means of such a large-area shielding of the suction opening, it can be particularly effectively prevented that undesired entry of liquid refrigerant into the suction device via the suction opening occurs during operation of the refrigerant circuit. This applies even if, for example, owing to a high fill level in the refrigerant accumulator, turbulences or turbulences should occur in the receiving space. In addition, by arranging the filter element in the refrigerant reservoir at a distance from the suction opening and, accordingly, large-area shielding of the suction opening, a low flow resistance can be achieved when the gaseous refrigerant enters the suction device via the suction opening. This is advantageous.Additionally or alternatively, the at least one filter element can comprise a cover element which rests on the suction opening. By means of such a small-area shielding of the suction opening, it is possible to prevent liquid refrigerant from entering the suction device via the suction opening during operation of the refrigerant circuit. In addition, the provision of such a small-area cover element at the intake opening is very low in complexity.The filter element can thus be positioned on the one hand in a compact and thus locally on or in the direct environment of the suction opening. On the other hand, the filter element can also be implemented over a large surface area, i.e. it shields a larger volume or area lying around the intake opening and in turn provides a further formed and shielded intake space for the intake opening in this way.In the case of the large-area shielding of the suction opening, the suction opening can be arranged within a cup-like device which has a base part and a cover part, wherein a casing wall of the cup-like device can be formed by the filter element. The jacket wall connects the base part to the cover part. The jacket wall is accordingly preferably arranged circumferentially around an opening gap drawn or bounded by the base part and the cover part. And a portion of the suction device having the suction opening can be inserted through the base part into the cup-like device.By a suitable alignment of the suction opening relative to the filter element, in particular opposite to the force of gravity, it can furthermore be avoided that refrigerant components that are liquid due to the force of gravity penetrate the filter element. This is advantageous in particular if the filter element is not completely tight for liquid refrigerant.Preferably, with respect to a transverse direction of the refrigerant accumulator, a center point of the discharge opening and a center point of the suction opening are at a greater distance from one another than two side walls of the receiving space. Here, the side walls are opposite one another in a further transverse direction containing a center of gravity of the refrigerant accumulator. In other words, the further transverse direction runs through the center of gravity of the refrigerant accumulator. This ensures that the discharge opening and the suction opening are spaced apart from one another by a particularly large distance, preferably by a maximum distance, in a plane lying perpendicular to a vertical direction of the refrigerant accumulator. This is advantageous in order to prevent liquid refrigerant emerging from the discharge opening from easily and directly reaching the suction opening of the suction device and thus possibly forming a short circuit for flow.The large distance between the centers of the discharge opening and the suction opening can be realized particularly easily if the refrigerant accumulator has a shape which deviates from a rotationally symmetrical shape of the refrigerant accumulator. For example, the refrigerant reservoir can be rectangular in cross section, wherein the discharge opening and the suction opening can be arranged in diagonally opposite corner regions of the rectangle. This is conducive to providing a large distance of the centers of the discharge port and the suction port from each other. A further geometrically advantageously implementable cross section would be that of an ellipse or an oval with the position of the discharge opening and of the suction opening at a maximum distance from one another on the longitudinal axis of the cross section.An end region of the suction device preferably has an orifice opening, wherein the refrigerant originating from the receiving space of the refrigerant accumulator can be supplied or can be supplied to the compressor via the orifice opening. In this case, the end region of the suction device passes through a passage opening formed in a cover of the refrigerant accumulator, and the end region of the suction device is sealed off from a circumferential edge of the passage opening.By such a gap-free mounting of the end region when it is guided through the passage opening formed in the cover of the refrigerant accumulator, it is possible to prevent liquid refrigerant from being extracted from the refrigerant accumulator via gaps or leaks in a particularly reliable manner. Rather, it can be achieved in this way that the two-phase mixture, which contains portions of the gaseous and the liquid refrigerant, can only pass out of the refrigerant reservoir via the suction device. This is advantageous. If a gap-free implementation of the joint of the suction device in the cover cannot be ensured reliably due to manufacturing tolerances, these gaps can be sealed off in a flow-preventing and completely reliable manner by additionally provided sealing elements, such as an O-ring.In particular if the suction device is formed from at least two parts which are coupled to one another in order to provide the suction device, it is advantageous if the parts are connected to one another in a materially integral manner at a corresponding coupling point and / or are connected to one another in a sealing-tight contact. Thus, even in the multi-part construction of the suction device, it can be ensured that liquid refrigerant enters the suction device only at a defined location such as the inlet for the liquid refrigerant, i.e. the above-described and preferably provided second suction section. This is advantageous.In particular, by sealing the end region toward the circumferential edge of the passage opening and / or by tightly joining the suction device in the multi-part construction of the suction device, it can be achieved that internal leaks are avoided. Therefore, such a minimization of joints is advantageous with regard to a stable formation of a vapor content to be set and provided at the outlet of the refrigerant accumulator.Preferably, a bottom of the refrigerant reservoir is at least partially funnel-shaped. It can thus easily be achieved that oil and / or similar lubricant collects in the funnel-shaped region of the base. In this case, the suction device has an inlet for liquid refrigerant in the vicinity of the base. Accordingly, the inlet or second suction section is placed as far as possible in this partial region of the refrigerant reservoir, and the oil can be introduced from the region of the funnel very easily together with the liquid refrigerant into the suction device.The lubricant can accordingly be introduced into the gaseous refrigerant via the inlet together with the liquid refrigerant, wherein the two-phase mixture formed in this way is extracted from the refrigerant accumulator via the extraction device during operation of the refrigerant circuit. The application of the lubricant or oil to the compressor and with the liquid refrigerant fraction in the two-phase mixture is advantageous for stable operation of the refrigerant circuit.The suction device can be designed in particular as a tube which has a U-shape. In this case, the inlet for the liquid refrigerant or refrigerant-oil mixture can be formed in particular at a reversal point of the U-shaped tube. It can thus be ensured that the inlet for the liquid refrigerant-oil mixture is generally below a liquid level which the liquid refrigerant forms together with the oil fraction dissolved in the refrigerant in the refrigerant accumulator during operation of the refrigerant circuit. This is advantageous for ensuring a defined suction of liquid refrigerant via the inlet of the suction device.Alternatively, the suction device can be provided by two coaxially arranged tubes, wherein the outer tube has the suction opening and the inner tube has the opening opening. Such a design of the suction device is advantageous in particular when the space conditions in the receiving space of the refrigerant reservoir make it difficult to accommodate a suction device which is designed as a U-shaped tube.Preferably, the receiving space of the refrigerant accumulator is divided by means of a partition into a first subspace and a second subspace. Here, the partition wall has at least one first passage for liquid refrigerant, and the partition wall has at least one second passage for gaseous refrigerant. By providing the partition wall, it can be ensured particularly well that turbulences occurring in the first subspace do not have any effects on the second subspace.Preferably, the inlet pipe is arranged in the first compartment and the suction device is arranged in the second compartment. As a result, the suction device is accommodated in the refrigerant reservoir particularly unaffected by events in the first subspace. This is advantageous in order to particularly largely avoid entry or penetration of liquid refrigerant into the suction device via the suction opening. The settling effect brought about by means of the separating wall has an advantageous influence on the quality of the refrigerant gas phase passing into the suction opening. In particular, the second passage can be provided, if required, with a flow-smoothing element such as a further filter element in order to separate out any entrained liquid components.Preferably, the first passage provided for the liquid refrigerant is arranged in the region of a base of the refrigerant accumulator, wherein the second passage provided for the vapor refrigerant is arranged in the region of a cover of the refrigerant accumulator. On the one hand, it is thus ensured that there is a fluidic connection between the two subspaces. In addition, this ensures that a liquid level of liquid refrigerant-oil mixture in the two subspaces is always the same and, as a result, the inlet or second suction section is always surrounded by liquid refrigerant-oil mixture.Preferably, with respect to a vertical direction of the refrigerant accumulator, the discharge opening of the inlet pipe is located lower than the suction opening of the suction device. This is also advantageous with regard to preventing the suction opening from being acted upon by liquid refrigerant or by liquid refrigerant fractions which can emerge from the discharge opening of the inlet pipe during operation of the refrigerant circuit.It has been found to be further advantageous if the refrigerant reservoir has, in the region of the inlet pipe, means for reducing the application of liquid refrigerant to the suction opening. These means can be provided by a corresponding shape or design of the inlet pipe.In particular, the design of the inlet pipe can ensure that the refrigerant flow entering the receiving space via the inlet pipe is guided along the inner side of a wall of the refrigerant accumulator. This prevents, on the one hand, foaming and swirling of the liquid refrigerant located in the refrigerant accumulator. In addition, centrifugal effects can be used in this way in order to achieve a liquid separation in the incoming refrigerant. Both are advantageous in order to prevent the suction opening from being acted upon as far as possible by liquid refrigerant.Furthermore, it is advantageous if a direct impingement of refrigerant entering the receiving space via the inlet pipe on refrigerant already stored in the refrigerant accumulator is omitted. This is because foaming and swirling of the refrigerant located in the refrigerant accumulator are prevented in this way.Accordingly, the means can comprise decentrally placing the inlet pipe on the refrigerant accumulator and / or an alignment of at least a partial region of the inlet pipe, which avoid an inflow of the refrigerant in the vertical direction of the refrigerant accumulator or in the vertical direction as far as possible. Furthermore, the means may comprise at least one baffle plate and / or baffle cap, which may be arranged downstream of the discharge opening of the inlet pipe in the receiving space.Additionally or alternatively, the discharge opening of the inlet pipe may have a shape in cross section that deviates from a round shape. For example, the discharge opening can be flat, in particular elliptical in cross section. This is also advantageous in order to prevent vortices from occurring in the receiving space when the refrigerant flows into the refrigerant accumulator. In particular, this applies when the inlet pipe has a curved shape in which a portion having the discharge opening is oriented obliquely with respect to a further portion of the inlet pipe.The motor vehicle according to the invention has a refrigerant circuit according to the invention. This ensures that during operation of the refrigerant circuit, the vapor content of the refrigerant extracted from the refrigerant accumulator is particularly insensitive to different filling levels of refrigerant in the receiving space of the refrigerant accumulator.The refrigerant circuit is preferably part of a refrigeration system designed for cooling and / or for heating a passenger compartment of the motor vehicle without or with heat pump functionality. Thus, during operation of the refrigerant circuit, a high driving comfort for occupants of the passenger compartment of the motor vehicle can be achieved.The advantages and preferred embodiments described for the refrigerant circuit according to the invention also apply to the motor vehicle according to the invention and vice versa.Accordingly, the invention also includes developments of the motor vehicle according to the invention, which have features as have already been described in connection with the developments of the refrigerant circuit according to the invention. For this reason, the corresponding developments of the motor vehicle according to the invention are not described again here.The motor vehicle according to the invention is preferably designed as a motor vehicle, in particular as a passenger car or truck, or as a passenger bus.The invention also includes the combinations of the features of the described embodiments. The invention therefore also comprises implementations which each have a combination of the features of a plurality of the described embodiments, provided that the embodiments have not been described as mutually exclusive.Exemplary embodiments of the invention are described below. The following shows: FIG. 1 schematically shows a low-pressure refrigerant accumulator for a refrigerant circuit of a motor vehicle, wherein the refrigerant accumulator has a high and slender structure in the manner of a tube; FIG. 2 schematically shows the refrigerant accumulator, in which a base is funnel-shaped; FIG. 3 shows the refrigerant accumulator in a plan view, from which the widely spaced arrangement of an inlet pipe and a suction opening of a U-shaped suction pipe can be seen; FIG. 4 shows a detail and schematically of the arrangement of a filter element arranged as a shielding device in the region of the suction opening, wherein the shielding device is spaced apart from the suction opening; FIG. 5 schematically shows the arrangement of a filter element configured as a cover element at the suction opening, wherein the cover element rests on the suction opening and is formed by a wall material of a bag which contains a desiccant; FIG. 6 schematically shows a possible design of the inlet pipe and a baffle plate arranged downstream of a discharge opening of the inlet pipe; FIG. 7 schematically shows a variant in which an impact cap is arranged downstream of the discharge opening of the inlet pipe; FIG. 8 schematically shows a curved configuration of the inlet pipe; FIG. 9 schematically shows a further curved configuration of the inlet pipe, wherein the discharge opening of the inlet pipe is configured in an ellipsoidal shape in cross section; FIG. 10 schematically shows an inlet pipe designed in the manner of a helical tube, by means of which the refrigerant entering a receiving space of the refrigerant accumulator is guided along an inner side of a wall of the refrigerant accumulator; FIG. 11 schematically shows the refrigerant accumulator, in which the receiving space is divided into a first subspace and a second subspace by means of a dividing wall; and FIG. 12 schematically shows the motor vehicle having the refrigerant circuit in which the low-pressure refrigerant accumulator is arranged.The exemplary embodiments explained below are preferred embodiments of the invention. In the exemplary embodiments, the described components of the embodiments each represent individual features of the invention that are to be considered independently of one another and that also develop the invention independently of one another. Therefore, the disclosure is intended to include combinations of the features of the embodiments other than those illustrated. Furthermore, the described embodiments can also be supplemented by further features of the invention that have already been described.In the figures, identical reference numerals designate functionally identical elements.FIG. 1 shows a schematic sectional view of a refrigerant accumulator 10, which is designed as a low-pressure accumulator. Accordingly, the refrigerant accumulator 10 is disposed in a refrigerant circuit 12 (see FIG. 12 ) downstream of an evaporator 14 of the refrigerant circuit 12 and upstream of a compressor 16 of the refrigerant circuit 12. The refrigerant circuit 12 further comprises a refrigerant cooler 18, which can be designed as a condenser or as a gas cooler depending on the refrigerant used. The refrigerant coming from the compressor 16 is cooled in the refrigerant cooler 18 and then expanded by means of an expansion device 20. The expanded refrigerant is then fed to the evaporator 14.According to FIG. 12, the refrigerant circuit 12 can be used in a motor vehicle 22. In this case, the refrigerant circuit 12 can be part of a refrigeration system designed for cooling and / or for heating a passenger compartment 24 of the motor vehicle 22, with or without a heat pump function.By using the subsequently described refrigerant accumulator 10 in the refrigerant circuit 12, it is particularly largely ensured that a vapor content in a two-phase mixture, which is drawn in by the compressor 16, lies in a predetermined range of possible vapor contents of refrigerant.The two-phase mixture contains, in addition to the gaseous refrigerant, liquid refrigerant or liquid refrigerant components and a lubricant, which circulates in the refrigerant circuit 12 together with the refrigerant, for lubricating the compressor 16.Referring to FIG. 1, the refrigerant accumulator 10 includes an inlet pipe 26 having a discharge port 28. Via the discharge opening 28, the refrigerant coming from the evaporator 14 can enter or be introduced into a receiving space 30 of the refrigerant accumulator 10. The inflow of the refrigerant coming from the evaporator 14 via the inlet pipe 26 into the receiving space 30 of the refrigerant accumulator 10 is illustrated in FIG. 1 by a first arrow 32.Furthermore, the refrigerant accumulator 10 has a suction device 34, which can be designed in particular as a U-shaped tube. The suction device 34 or the suction pipe has a suction opening 36, via which gaseous refrigerant originating from the receiving space 30 can be introduced into the suction device 34. Furthermore, the intake pipe or the suction device 34 has an end region 38 with an opening 40. The refrigerant originating from the receiving space 30 of the refrigerant accumulator 10 can be supplied to the compressor 16 via the orifice 40.The two-phase refrigerant-oil mixture, which is extracted from the refrigerant accumulator 10 via the extraction device 34 and contains gaseous refrigerant and liquid refrigerant 48 originating from the receiving space 30 and mixed with oil components, is illustrated in FIG. 1 by a further arrow 42.In addition, FIG. 1 shows the entry of the gaseous refrigerant into the suction device 34 via the suction opening 36 by means of a curved arrow 44.In the present case, it is to be ensured that only gaseous refrigerant reaches the suction device 34 via the suction opening 36. This is because a desired fraction of liquid refrigerant 48 is added to the gaseous refrigerant during operation of the refrigerant circuit 12 via an inlet 46 of the suction device 34, which can be designed, for example, as a bore.In the refrigerant accumulator 10 shown in FIG. 1, this inlet 46 is arranged in a reversal region of the U-shaped tube, through which the suction device 34 can be provided. Via the inlet 46, a definedly adjusted proportion of liquid refrigerant 48 or of liquid refrigerant 48 with a proportion of oil or similar lubricant reaches the suction device 34.The inlet 46 of the suction device 34 is preferably located in the vicinity of a base 50 of the refrigerant reservoir 10, and it can thus be ensured that even in the case of low filling levels of the liquid refrigerant 48 in the receiving space 30 of the refrigerant reservoir 10, some liquid refrigerant 48 always reaches the suction device 34 via the inlet 46.Together with the liquid refrigerant 48, the oil or similar lubricant also reaches the suction device 34. The lubricant contained in particular in the liquid refrigerant 48 is sucked together with the two-phase refrigerant mixture from the compressor 16 via the suction device 34 out of the refrigerant reservoir 10.In FIG. 1, a vertical direction z of the refrigerant accumulator 10 is illustrated by an arrow. It can therefore be seen from FIG. 1 that, with respect to the vertical direction z of the refrigerant reservoir 10, the discharge opening 28 of the inlet pipe 26 is preferably located lower than the suction opening 36 of the suction device 34.Furthermore, it is favorable if the suction opening 36 and the discharge opening 28 are positioned at the greatest possible distance from one another with respect to their respective center points. In this regard, reference is made to FIG. 3. Accordingly, a housing 52 of the refrigerant accumulator 10 can have a shape deviating from a rotationally symmetrical shape. For example, FIG. 3 shows that the housing 52 of the refrigerant accumulator 10 can be rectangular in cross section.Accordingly, with respect to a transverse direction y of the refrigerant accumulator 10, centers of the discharge opening 28 and of the suction opening 36 are at a greater distance from one another than two side walls 54, 56 of the receiving space 30. In particular, the discharge opening 28 of the inlet pipe 26 and the suction opening 36 of the suction device 34 can be arranged in corner regions of the rectangle, wherein the corner regions are opposite one another in the diagonal direction of the rectangle.In addition, by means of components arranged in the receiving space 30, a shielding of the suction opening 36 from the discharge opening 28 can be achieved. As an example of such a component, a baffle plate 58 is shown in FIG. 6, on which the refrigerant exiting from the inlet pipe 26 impinges. In addition, the baffle plate 58 ensures that the refrigerant emerging from the inlet pipe 26 does not flow into the receiving space 30 along the vertical direction z, but rather is deflected as far as possible toward an inner side of walls of the housing 52.It can further be seen from FIG. 1 that the extraction of the refrigerant from the refrigerant accumulator 10 and thus the extraction opening 36 is placed comparatively far above in the vertical direction z, for example close to a cover 60 of the refrigerant accumulator 10; this also advantageously entails that the storage volume for the liquid refrigerant 48 in the receiving space 30 is particularly large.According to FIG. 1, the refrigerant accumulator 10 can preferably have a high, slender structure in the manner of a tube. This ensures that the refrigerant entering the receiving space 30 via the inlet pipe 26 does not lead to a swirling of already stored, preferably liquid refrigerant 48. This is because a particularly large distance of the refrigerant inlet, i.e. the discharge opening 28, from a liquid level of the liquid refrigerant 48 can be achieved in this way.In order to prevent the refrigerant entering the receiving space 30 from directly impinging on the already stored refrigerant, the refrigerant flow can be guided along an inner side of a wall of the housing 52, for example. A corresponding shape of the inlet pipe 26 designed in the manner of a helical tube is schematically illustrated in FIG. 10. Accordingly, the inlet pipe 26 may be formed as a pipe bend which is laid along the inner side of a wall of the housing 52 in order to bring the refrigerant 48 specifically into the edge zone of the receiving space 30. Furthermore, centrifugal effects can be used in this way in order to separate the liquid refrigerant 48 or the liquid portion of the refrigerant 48 from the refrigerant flow flowing into the receiving space 30.A further example of a shielding element for preventing the refrigerant entering the receiving space 30 via the inlet pipe 26 from directly impinging is shown in FIG. 7 in the form of an impact cap 61 onto which the refrigerant exiting from the discharge opening 28 impinges.It is also clearly evident from FIG. 1 and from FIG. 3 that preferably no central entry of the refrigerant into the receiving space 30 via the inlet pipe 26 is provided. Rather, the discharge opening 28 of the inlet pipe 26 is preferably arranged decentrally.The introduction of the refrigerant close to an edge of the housing 56 or close to the inner side of the housing 56 is preferably effected substantially along a plane spanned by the two transverse directions x, y (compare FIG. 3 ). This also serves to avoid a vertical refrigerant flow in the receiving space 30 and thus reduces a risk of swirling, in particular in the vertical direction z of the refrigerant accumulator 10.In order to realize such an introduction of the refrigerant into the receiving space 30 oriented in the plane spanned by the transverse directions x, y, the inlet pipe 26 can have a curved shape, as is shown, for example, in FIG. 8 and in FIG. 9. Accordingly, an end portion 62 of the inlet pipe 26 may be oriented inclinedly with respect to an inlet portion 64 of the inlet pipe 26.In the configuration of the curved inlet pipe or inlet pipe 26 shown in FIG. 9, a free end 66 of the end section 62 is additionally flatter than the region of the end section 62 arranged upstream. For example, by providing such a quasi-squeezed end region or end 66 of the inlet pipe 26, the discharge opening 28 can have substantially an ellipse shape or an ellipse profile.It is readily apparent from FIG. 2 that the bottom 50 of the refrigerant reservoir 10 can be funnel-shaped at least in regions. This is advantageous in particular in order to collect in the funnel the oil or the lubricant, which together with the liquid refrigerant 48 reaches the suction device 34 via the inlet 46.It can also be seen from FIG. 2 that the end region 38 of the suction device 34, which has the opening opening 40, preferably passes through a passage opening 68 formed in the cover 60 of the refrigerant accumulator 10. In this case, the end region 38 is preferably sealed off from a circumferential edge of the passage opening 68.This is advantageous in particular when the orifice opening 40 extends into a connecting piece (not shown), which can be arranged on the cover 60. The suction device 34 can be connected via this connecting piece to a corresponding line via which the refrigerant originating from the refrigerant accumulator 10 can be supplied to the compressor 16 (compare FIG. 4 ).If a leak exists at the circumferential edge of the passage opening 68, for example in the form of an annular gap or the like, gaseous and / or liquid refrigerant could be sucked directly from the receiving space 30 of the refrigerant accumulator 10 via the connecting piece. This can be avoided to a particularly great extent if the end region 38 is arranged without gaps or in a sealing-fit manner in the passage opening 68 which is formed in the cover 60.In the present case, the refrigerant reservoir 10 has at least one filter element for shielding the suction opening 36 from undesired entry of refrigerant 48 from the receiving space 30 via the suction opening 36 into the suction device 34. The at least one filter element is permeable to gaseous refrigerant, but is designed to retain liquid refrigerant 48.According to FIG. 3, the suction opening 36 can have a cover element 70 as the filter element, which rests on the suction opening 36. When the filter element is provided as the cover member 70 (see FIG. 3 ) directly covering the suction port 36, a small-area and thus local separation device for separating the liquid refrigerant 48 is provided by the filter element. According to FIG. 3, the covering element 70 is flowed through axially with respect to the suction opening 36 of the suction device 34.As a further variant (not shown in detail in the present case), the filter element can be designed in the manner of an extended tube element of the suction device 34, so that the gaseous refrigerant enters the suction opening 36 in the radial direction. In addition to the aforementioned axial or vertical flow and the radial flow through the cover element 70, intermediate layers or other alignments of the cover element 70 or alignments between them and the associated flows through this filter element are also conceivable.Additionally or alternatively, it is possible to shield the entire suction environment of the suction device 34 over a large area. Such a filter element, which is designed as a large-area shielding device 72, is shown schematically in FIG. 4. Here, the filter element in the form of the shielding device 72 is arranged in the receiving space 30 of the refrigerant accumulator 10 at a distance from the suction opening 36.According to FIG. 4, the suction opening 36 can be arranged within a cup-like device 90 which is arranged in the receiving space 30 of the refrigerant accumulator 10. The cup-shaped or pot-shaped device 90 has a base part 92 and a cover part 94. A jacket wall of the cup-like device 90 is formed by the filter element according to FIG. 4. In other words, the filter element in the form of the shielding device 72 spaced apart from the suction opening 36 is designed as the casing wall of the cup-like device 90.The jacket wall connects the base part 92 to the cover part 94, wherein these surface elements can be aligned in particular substantially parallel to one another. In the variant of the refrigerant accumulator 10 shown in FIG. 4, a section of the suction device 34 having the suction opening 36 is also introduced into the cup-like device 90 through an opening formed in the base part 92.However, other configurations of the shielding device 72 are also possible. For example, the filter element in the form of the shielding device 72 can span over a large area over the suction opening 36 and in this case be fastened to an inner side of at least one wall of the housing 52 of the refrigerant reservoir 10. By means of such a large-area shielding in the vicinity of the suction opening 36, an undesired penetration of liquid refrigerant 48 into the suction device 34 via the suction opening 36 can likewise be very effectively prevented.A further variant in the use of the at least one filter element will be explained with reference to FIG. 5. The filter element is formed by a wall material 74 of a bag 76 arranged in the receiving space 30, wherein the bag 76 contains a desiccant, for example in the form of granules 78. The individual grains or pellets of the granulate 78 are schematically indicated in FIG. 5, wherein for the sake of simplicity only some of the pellets of the granulate 78 are provided with a reference sign.According to FIG. 5, the bag 76 is not filled with the granulate 78 in an impact manner. Rather, a partial region of the bag 76 which is free of the desiccant in the form of the granulate 78 provides the filter element which rests on the suction opening 36 of the suction device 34.Additionally or alternatively, a dryer unit separate from the filter element in the form of the bag 76 can be provided for drying the refrigerant located in the receiving space 30, for example in the form of a further bag 76 with a desiccant, for example in the form of the granulate 78. Consequently, the dryer unit may be placed at any location in the refrigerant accumulator 10 or refrigerant collector.In order to avoid gravity effects and thus penetration of liquid coolant parts through the filter element in the form of the wall material 74 into the suction opening 36, an adapted position of the suction opening 36 can be realized if necessary. In this case, it can be provided that the gaseous refrigerant is sucked into the suction device 34 via the suction opening 36 counter to the vertical direction z of the refrigerant accumulator 10 illustrated by an arrow in FIG. 1. Likewise, the suction opening 36 provided with the wall material 74 can be oriented at an inclination for this purpose, in particular perpendicular, to a plane spanned by the transverse directions x, y of the refrigerant accumulator 10.A further possibility, which can additionally or alternatively be realized, of preventing as far as possible an ingress of liquid refrigerant 48 via the suction opening 36 into the suction device 34 is to be explained with reference to FIG. 11. Accordingly, the receiving space 30 of the refrigerant accumulator 10 can be divided into a first subspace 82 and a second subspace 84 by means of a dividing wall 80. Here, the inlet pipe 26 is arranged in the first subspace 82 and the suction device 34 in the second subspace 84. The first passage 86 is preferably disposed near the bottom 50 of the refrigerant accumulator 10.Furthermore, the partition 80 has at least one second passage 88 for gaseous or vapor refrigerant. The second passage 88, which is arranged in the present case in the vicinity of the cover 60 of the refrigerant accumulator 10, provides a fluidic connection of the vapor spaces or gas spaces of the two subspaces 82, 84. and the first passage 86 ensures that the liquid level of the liquid refrigerant 48 is of the same height throughout the refrigerant accumulator 10.Overall, the examples show how advantageously design options for stabilizing the vapor content can be provided in the low-pressure refrigerant accumulator 10 or accumulator.

Claims

Refrigerant circuit (12) for a motor vehicle (22), having a refrigerant accumulator (10) which is arranged downstream of an evaporator (14) of the refrigerant circuit (12) and upstream of a compressor (16) of the refrigerant circuit (12), wherein the refrigerant accumulator (10) has an inlet pipe (26) with a discharge opening (28) via which the refrigerant coming from the evaporator (14) can be introduced into a receiving space (30) of the refrigerant accumulator (10), wherein the refrigerant accumulator (10) has a suction device (34) with a suction opening (36), and wherein gaseous refrigerant coming from the receiving space (30) can be introduced into the suction device (34) via the suction opening (36), wherein the refrigerant accumulator (10) has at least one filter element (70, 72, 74) which is permeable to the gaseous refrigerant and which is designed for retaining liquid refrigerant (48), wherein the suction device (34) is protected by the at least one filter element (70, 72, 74) from penetration of liquid refrigerant (48) into the suction device (34) via the suction opening (36), characterized in that the at least one filter element is formed by a wall material (74) of a bag (76) arranged in the receiving space (30), wherein the bag (76) contains a drying agent (78), and wherein a partial region of the bag (76) free of the drying agent (78) provides the at least one filter element which rests on the suction opening (36) of the suction device (34).Refrigerant circuit (12) according to Claim 1, characterized in that the at least one filter element comprises a shielding device (72) which is arranged in the receiving space (30) of the refrigerant accumulator (10) at a distance from the suction opening (36).Refrigerant circuit (12) according to one of the preceding claims, characterized in that the at least one filter element comprises a cover element (70) which rests on the suction opening (36).Refrigerant circuit (12) according to one of the preceding claims, characterized in that, with respect to a transverse direction (y) of the refrigerant accumulator (10), a centre point of the discharge opening (28) and a centre point of the suction opening (36) are at a greater distance from one another than two side walls (54, 56) of the receiving space (30) which are opposite one another in a further transverse direction (x) containing a centre of gravity of the refrigerant accumulator (10), and / or the refrigerant accumulator (10) has a shape deviating from a rotationally symmetrical shape.Refrigerant circuit (12) according to one of the preceding claims, characterized in that an end region (38) of the suction device (34), which end region has an orifice opening (40) via which the refrigerant originating from the receiving space (30) of the refrigerant accumulator (10) can be fed to the compressor (16), passes through a passage opening (68) formed in a cover (60) of the refrigerant accumulator (10), wherein the end region (38) of the suction device (34) is sealed off from a circumferential edge of the passage opening (68).Refrigerant circuit (12) according to one of the preceding claims, characterized in that a base (50) of the refrigerant reservoir (10) is at least regionally funnel-shaped, wherein the suction device (34), which is in particular designed as a tube having a U-shape, has an inlet (46) for liquid refrigerant (48) in the vicinity of the base (50).Refrigerant circuit (12) according to one of the preceding claims, characterized in that the receiving space (30) of the refrigerant accumulator (10) is divided by means of a dividing wall (80) into a first subspace (82) and into a second subspace (84), wherein the dividing wall (80), in particular in the region of a base (50) of the refrigerant accumulator (10), has at least one first passage (86) for liquid refrigerant (48), wherein the dividing wall (80), in particular in the region of a cover (60) of the refrigerant accumulator (10), has at least one second passage (88) for gaseous refrigerant, and wherein the inlet pipe (26) is arranged in the first subspace (82) and the suction device (34) is arranged in the second subspace (84).Refrigerant circuit (12) according to one of the preceding claims, characterized in that, with respect to a vertical direction (z) of the refrigerant accumulator (10), the discharge opening (28) of the inlet pipe (26) is located lower than the suction opening (36) of the suction device (34) and / or the refrigerant accumulator (10) has, in the region of the inlet pipe (26), means for reducing impingement of the suction opening (36) with liquid refrigerant (48).Motor vehicle (22) having a refrigerant circuit (12) according to one of the preceding claims, wherein the refrigerant circuit (12) is part of a refrigeration system designed for cooling and / or for heating a passenger compartment of the motor vehicle (22), in particular having a heat pump functionality.

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