EP1293736B1 - Coolant system for a vehicle air conditioner and cooling device for the coolant system - Google Patents

Abstract

The system has a cooling device (12) that passes a gaseous medium to be cooled containing oil and an oil separation unit (46). The oil separation unit is integrated into the cooling device. The oil separation unit is in the form of a wire and/or metal plate structure through which the gaseous medium can pass. AN Independent claim is also included for the following: a cooling device for an inventive system.

Description

The invention relates to a refrigeration system, in particular refrigeration cycle system for air conditioning of a vehicle, with a cooling device, which is enforceable by means of a gas medium to be cooled and oil (refrigeration oil) containing, and with a Ölabscheideeinheit which is integrated in the cooling device.

Refrigeration systems and cooling devices of the type mentioned are known. In particular, in refrigeration cycle systems for vehicle air conditioning compressors are used, which require a proportion of oil (refrigeration oil) in a self-enforcing refrigerant (gas medium) for their lubrication. Since, especially for cost reasons, such compressors do not have their own oil sump or oil separator to keep the refrigeration oil away from other refrigeration cycle components, relatively high refrigeration oil components circulate through the refrigerant through all components of the refrigeration cycle with correspondingly negative effects on the achievable refrigeration capacity or on the refrigeration capacity.

Furthermore, it is known to integrate an oil separator in a hot gas line between a compressor and a condenser of a refrigeration cycle system. Such external oil separators are relatively large and expensive and usually have a relatively high basic charge with refrigeration oil for controlling the Kälteölrückflusses means of a float valve. These oil separators are designed for a relatively high separation efficiency of over 95%.

It is also known to integrate an oil separator in a compressor with oil sump. However, this leads to an undesirable enlargement of the housing dimensions and the masses of the (engine-mounted) compressor. Furthermore, effective cooling of the refrigeration oil in such a compressor is not possible.

In refrigeration cycle systems without oil separation, the refrigerant oil component circulating with the refrigerant is relatively large and leads to various performance and efficiency-reducing effects. In particular, there is a deterioration of the refrigerant side heat transfer coefficient due to a formation of a poor heat-conducting cold oil film. Furthermore, there is an increase in the refrigerant side pressure loss due to a higher viscosity of the refrigerant-refrigerant mixture. It is also disadvantageous that an increase in the boiling temperature of the refrigerant is effected. Due to the good solubility of the refrigerant oil in the refrigerant remains in the evaporation of the mixture always a part of the refrigerant dissolved in the oil and does not contribute to the cooling.

From the US-A-1425246 is a cooling device with Ölabscheideeinheit out, which is designed as a zig-zag curved, impermeable plate and arranged vertically extending downwards. Separated oil must overflow over the edges of the plate formed by the zig-zag shape and collects at the lower end edge of the plate.

The US 6276 165 shows a cold system according to the preamble of claim 1.

It is an object of the invention to provide a refrigeration system of the type mentioned, in which an oil separation from a gas medium possible and at the same time a relatively simple design of the refrigeration system is feasible.

This object is achieved by a refrigeration system having the features of claim 1. The cooling device (heat-dissipating component) may be a condenser or else a gas cooler, for example in circuits with supercritical heat dissipation. The Ölabscheideeinheit is preferably integrated on the hot gas medium side in the cooling device and is a technically relatively easy to implement solution, since no additional screw or the like may be required, as would be necessary, for example, in an integration of a Ölabscheiders in an extended hot gas line. Advantageously, the integrated in the cooling device Ölabscheideeinheit requires virtually no additional space. According to the invention, the oil separation unit, which can be penetrated by the gas medium, contains at least one substantially vertically downwardly extending oil drainage edge, which has a U-shaped or V-shaped profile in cross-section with respect to an enforcement direction of the gas medium. As a result, a basically desired refrigeration oil drain on the oil separation unit is promoted or supported, and tearing off of cold oil droplets in the gas medium stream passing through the oil separation unit is prevented.

Advantageously, the Ölabscheideeinheit is formed as enforceable by means of the gas medium wire and / or metal plate structure. In this case, the Ölabscheideeinheit may be formed, for example, as a pack of a knitted wire, a wire mesh, a wire mesh or a stack of expanded metal plates. Such Ölabscheideeinheit can be integrated in a relatively simple manner in the cooling device and is for oil separation of a hot gas medium flows through (permeates). Of course, other suitable design possibilities of the oil separation unit are conceivable.

The oil separation unit preferably contains a surface-enlarging geometric macrostructure. In this context, macrostructuring means a geometric structuring of the oil separation unit superimposed on the enforcement structure of the gas medium on the front and / or rear surface (boundary surface) of the oil separation unit, superimposed on the enforcement structure (for example wire mesh). The Ölabscheideeinheit can be formed, for example, as a longitudinally pleated pack, by means of which an improved separation effect of the refrigerant oil from the oil separation unit passing through the gas medium and an optimized cooling oil drain from the Ölabscheideeinheit can be achieved. Alternatively, a curved configuration of the front and / or rear side (entrance or exit surface) of the Ölabscheideeinheit to achieve the said effects possible.

Advantageously, the Ölabscheideeinheit is integrated in an enforceable by the gas medium collecting tube of the cooling device, which is connected to a cooling device connecting the cooling device with an evaporator suction line of the refrigeration system. In such a manifold is a manifold or an inlet-side portion of a manifold of the cooling device, in which in a relatively simple and effective manner, the Ölabscheideeinheit is integrated. In this embodiment, it is advantageously possible to insert the oil separation unit, for example in the form of a wire and / or metal plate structure during the manufacturing process of the cooling device and in particular before a soldering process for producing the same in the collecting tube in a montage-favorable manner or use.

Advantageously, by means of the oil separation unit arranged in the collection pipe, a first chamber upstream of the gas medium in the direction of penetration and a second, downstream chamber are formed. In this case, the upstream chamber of the pre-distribution of hot gas medium-refrigerant oil mixture is used on the entire face of the Ölabscheideeinheit, while the downstream chamber further homogenization of the self-adjusting velocity distribution of the now largely free of refrigerant oil gas medium via the associated cooling lines (for example, capacitor lines) of the cooling device, so that a largely equal gas medium mass flow (refrigerant mass flow) can be achieved in all cooling tubes (condenser tubes) which are connected to the collecting tube.

The Ölabscheideeinheit is frontally preferably spaced from the respective inlet opening of gas medium cooling lines arranged. This avoids that in the formed, for example, as a wire and / or metal plate structure Ölabscheideeinheit separated and along selbiger down running refrigerant oil can get into the cooling lines due to capillary action.

Advantageously, the manifold in the first chamber in a lower region to an oil drain opening. By means of such an oil drain opening a reliable cooling oil discharge from the manifold and optionally a cooling oil return in the refrigeration system is ensured in a simple manner.

According to a preferred embodiment, the collecting tube has a boundary wall in the lower region, whose edge facing the oil drain opening is arranged lower than its edge directed toward the gas-medium cooling lines. In order to prevent significant amounts of refrigerant oil can reach the bottom cooling line of the cooling device (for example, condenser), the oil drain opening is preferably mounted lower than the lowest, connected to the manifold cooling line, said pointing to the oil drain opening edge of the boundary wall for this lower is as edge directed to the gas medium cooling lines.

The boundary wall can be formed as a flat, obliquely arranged sheet metal or as a stepped shaped sheet metal. Optionally, the boundary wall may be a partition wall integrated within the cooling device, which in the case of a shaped sheet is preferably designed as a deep-drawn part or as a flow-press part.

Advantageously, the oil drain opening is connected to an oil return line, in particular designed as a capillary tube. In a Kapillarrohrausbildung the oil return line with respect to pressure loss (diameter, length) is designed so that at usual pressure differences between high pressure and low pressure side separated by means of the Ölabscheideeinheit Kälteölmassenstrom completely from the manifold (manifold) of the cooling device (condenser) can be dissipated, but in the presence a gas medium at the oil drain opening of the gas medium mass flow (hot gas mass flow) remains negligibly small due to the lower density of the gas medium and due to the relatively small cross section of the oil drain opening or the oil return line.

According to an alternative embodiment, the oil drain opening can be connected to the oil return line with the interposition of a throttle tube be. In this case, a reduction in pressure to a present Saugdruckniveau in the particular short throttle tube ("Orifice") takes place immediately before a point of confluence in a suction line. In this embodiment, the oil return line can thus be designed with a slightly larger diameter. Furthermore, this variant allows a more effective cooling of the refrigeration oil during its return through the oil return line, as a temperature-lowering expansion process only in an end (seen in oil return direction) of the oil return line and thus a larger temperature difference between the respective recirculating refrigeration oil in the oil return line and the ambient temperature can be used can. In addition, a more favorable control of the recirculating cold oil mass flow according to the principle of the throttle tube ("orifice") is possible.

Further advantageous embodiments of the invention will become apparent from the description.

Figur 1

ein Kältesystem in Form eines Kältekreislauf- systems anhand eines Blockschaltbildes;

Figur 2

eine schematische, teilweise geschnittene Seitenansicht einer detailliert dargestellten Kühleinrichtung des Kältesystems der Fi- gur 1;

Figur 3

ein Detail der Kühleinrichtung der Figur 2 in vergrößertem Maß- stab;

Figur 4

eine alternative Ausführungsform eines Details der Kühleinrich- tung der Figur 2 in vergrößertem Maßstab;

Figur 5

eine schematische Draufsicht einer alternativen Ölabscheideein- heit und

Figur 6

eine schematische Draufsicht einer weiteren, alternativen Ölab- scheideeinheit.

The invention will be explained in more detail in an embodiment with reference to an accompanying drawing:

FIG. 1

a refrigeration system in the form of a refrigeration cycle system based on a block diagram;

FIG. 2

a schematic, partially sectioned side view of a detail illustrated cooling device of the refrigeration system of Figure 1;

FIG. 3

a detail of the cooling device of FIG. 2 on an enlarged scale;

FIG. 4

an alternative embodiment of a detail of the cooling device of FIG. 2 on an enlarged scale;

FIG. 5

a schematic plan view of an alternative Ölabscheideein- unit and

FIG. 6

a schematic plan view of another, alternative Ölab- separation unit.

FIG. 1 shows a block diagram of a generally designated 10 refrigeration system, in particular a refrigeration cycle system, for example for air conditioning of a vehicle. The refrigeration system 10 includes a cooling device 12, which is operatively connected to an evaporator 14 to form a closed circuit. From the evaporator 14, a refrigerant line shown as arrow 22 leads to an expansion valve 16, from which a refrigerant line shown as arrow 24 leads to a connection point 26. The refrigerant is in particular a gas medium and, in the present embodiment, hot gas. In the connection point 26, oil (refrigeration oil) separated from the cooling device 12 is supplied to the refrigerant coming from the evaporator 14 by means of an oil return line shown as arrow 28 to form a refrigerant-oil mixture which is fed to a compressor 18 through a corresponding supply line according to arrow 30 becomes. From the compressor 18, a feed line shown as arrow 32 leads to the cooling device 12 to act on the same with the now under higher pressure refrigerant-oil mixture. Within the cooler 12 -in an integrated oil separator unit 46- takes place a later described in detail oil separation from the refrigerant-oil mixture, wherein the separated oil, as already mentioned, is passed through the oil return line shown as arrow 28 from the cooling device 12 to the connection point 26. The refrigerant is passed through the cooling device 12 and passed through a refrigerant return line (arrow 34) to a collector or dryer 20, from which a refrigerant return line shown as arrow 36 leads to the expansion valve 16. The expansion valve 16 is finally connected to the evaporator 14 by means of a return line shown by arrow 38. The lines 22, 24, 28, 30 are suction lines, while the lines 32, 34, 36, 38 are pressure lines.

FIG. 2 shows a schematic representation of a possible embodiment of a cooling device 12, which in the refrigeration system 10 of FIG. 1 can be used. In FIG. 3 is a detail of the cooling device 12 of FIG. 2 shown on an enlarged scale. The cooling device 12 of FIGS. 2 and 3 is connected to the supply line 32 for supplying the refrigerant-oil mixture according to arrow 40 in the cooling device 12. For this purpose, the cooling device 12 a collecting tube 48 which is bounded by a lower boundary wall 62 (partition). In the collecting pipe 48, the oil separation unit 46 is arranged such that a first upstream chamber 50 and a second downstream chamber 52 are formed with respect to the feeding direction (arrow 40) of the refrigerant-oil mixture. The Ölabscheideeinheit 46 is formed for example as a wire and / or metal plate structure and the refrigerant (gas medium) enforceable. In this case, the oil separation unit 46 is arranged spaced apart from the end face to a plurality of inlet openings 54 of refrigerant cooling lines 56 (gas medium cooling lines). In the first chamber 50 of the collecting tube 48 is located in the lower region of an oil drain opening 60, which lies directly above the boundary wall 42. The oil drain opening 60 is connected to an oil return line 28 designed in particular as a capillary tube for oil return according to arrow 44. The guided through the cooling device 12 refrigerant (gas medium) is returned through the refrigerant return line 34 according to arrow 42 back to the evaporator 14 (see also FIG. 1 ).

According to the in the FIGS. 2 and 3 illustrated embodiment of the cooling device 12, the boundary wall 62 is formed as a flat, obliquely arranged sheet. In this case, the side facing the oil drain opening 60 edge 64 of the boundary wall 62 is located lower than her to the refrigerant cooling lines 56 directed edge 66. This arrangement of the oil drain opening 60 below the bottom, connected to the manifold 48 cooling line 56 is possible, at the same time by means of Limiting wall 62 a reliable oil drain into the oil return line 28 can be achieved.

FIG. 4 shows an alternative embodiment with respect to the geometric configuration of the boundary wall 62. In this embodiment, the boundary wall 62 is formed as a stepped shaped sheet, wherein here the oil drain opening 60 facing edge 64 is located lower than the directed to the cooling lines 56 edge 66th

The oil separation unit 46 according to FIGS. 2 to 4 is formed as a wire and / or metal plate structure and has a substantially planar front structure (adjacent to the first chamber 50) and a correspondingly formed structure rear side (adjacent to the second chamber 52) on. According to the illustrated embodiments of the FIGS. 5 and 6 For example, the oil separation unit 46 may also have a surface-enlarging geometric macrostructure. In this case, the macrostructuring of the oil separation unit 46 proceeds in a plan view FIG. 5 zigzag (longitudinally pleated structure) while in FIG. 6 a concavely curved configuration of the oil separation unit 46 with respect to the refrigerant supply direction (arrow 40) is shown in a plan view thereof. In the embodiment according to FIG. 5 a downstream boundary surface 57 of the Ölabscheideeinheit 46 includes a plurality, in the present embodiment two, vertically downwardly extending oil drainage edges 58 having a cross-sectionally U- or V-shaped profile. By means of such oil drainage edges 58, a reliable and effective oil separation from the refrigerant-oil mixture is made possible. The oil separated in the oil separation unit 46 is discharged from the header through the oil return line 28 48 directed and the junction 26 (see also FIG. 1 ) supplied to form a closed oil circuit.

Compared with a traditional refrigeration system without oil separation resulting in overheating setting of the expansion valve 16 of about 7 K and a reduction of the circulating oil content of 6% to 1%, the thermodynamic advantages that the cooling capacity increased by about 2.5%, the cooling capacity at the same time Improved performance of about 11% and the compressor drive power in part-load operation (ie at the same cooling capacity) can be reduced by up to 18%.

Advantageously, the Ölabscheideeinheit 46, apart from a relatively thin and preferably flexible and therefore relatively easy to install oil return line 28, no additional space. In this case, takes place in the oil return line 28, an automatic cooling of the recirculating oil (refrigeration oil). When executing the oil separation unit 46 (deposition package) made of aluminum, the purity of the variety of the cooling device 12 (capacitor or capacitor module) is maintained.

Claims (12)

1. Coolant system, in particular a coolant circulation system for the air-conditioning of a vehicle, comprising a cooling device which can be penetrated by means of an oil-containing gaseous medium to be cooled, and comprising an oil separating unit which is integrated in the cooling device, characterized in that the oil separating unit (46), which can be penetrated by gaseous medium, contains at an interface (57) which is downstream in relation to a direction of penetration (40) of the gaseous medium at least one oil run-off rim (58) which extends substantially perpendicularly downward and has a profile which is U or V-shaped in cross section.
2. Coolant system according to claim 1, characterized in that the oil separating unit (46) is configured as a wire and/or metal plate structure which can be penetrated by means of the gaseous medium.
3. Coolant system according to any one of the preceding claims, characterized in that the oil separating unit (46) has a geometric macrostructure which increases the surface area.
4. Coolant system according to any one of the preceding claims, characterized in that the oil separating unit (46) is arranged at the end face so as to be set apart from the respective opening (54) for the entry of gaseous medium cooling lines (56).
5. Coolant system according to any one of the preceding claims, characterized in that the oil separating unit (46) is integrated in a collector pipe (48), which can be penetrated by the gaseous medium, of the cooling device (12), which collector pipe is connected to a suction line (32), connecting the cooling device (12) to an evaporator (14), of the coolant system (10).
6. Coolant system according to claim 5, characterized in that a first chamber (50), which is upstream in relation to the direction of penetration (40) of the gaseous medium, and a second, downstream chamber (52) are formed by means of the oil separating unit (46) which is arranged in the collector pipe (48).
7. Coolant system according to one of claims 5 and 6, characterized in that the collector pipe (48) in the first chamber (50) has an oil run-off opening (60) in a lower region.
8. Coolant system according to claim 7, characterized in that the collector pipe (48) has in the lower region a delimiting wall (62), of which the edge (64) facing the oil run-off opening (60) is arranged lower than its edge (66) directed toward the gaseous medium cooling lines (56).
9. Coolant system according to claim 8, characterized in that the delimiting wall (62) is configured as a planar, obliquely arranged metal sheet or as a stepped profiled metal sheet.
10. Coolant system according to any one of claims 7 - 9, characterized in that the oil run-off opening (60) is connected to an oil return line (28) which is configured, in particular, as a capillary tube.
11. Coolant system according to claim 10, characterized in that the oil run-off opening (60) is connected to the oil return line (28), a throttle pipe being inserted therebetween.
12. Coolant system according to any one of the preceding claims, characterized in that the cooling device (12) is a condenser.

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