EP1724536B1 - Heat exchanger with accumulator - Google Patents

Description

The invention relates to a device for the treatment of the refrigerant which circulates in an air conditioning circuit, comprising: compressor, gas cooler, evaporator and expansion element and thereby passes through a high pressure side and a low pressure side, in which the refrigerant has different temperature, wherein the device comprises a flat multi-chamber tube, through which the one side flows and which is disposed in a container through which the other side flows to serve as an intermediate heat exchanger, wherein in the container, an accumulator chamber, a heat exchange chamber and a wall therebetween are formed.

This device, which is often referred to as an internal heat exchanger in trans-critical air conditioning circuits, is from the DE 196 35 454A1 is known and can be considered advanced, because the achievable heat exchange rate meets the requirements and because it also includes a Akkumulatorkammer. However, the fabrication of this device - lying in the installation space of the motor vehicle - seems to be rather expensive, since the tubes are deformed as spirals and the insertion of the heat-conducting fins between the turns of the coils could also be complicated.

In the DE 103 22 028 B4 an intermediate heat exchanger was integrated as a coaxial tube in the manifold of the evaporator, creating a very compact design was created, which is apparently also cheaper to produce, but which has no accumulator.

In the German patent DE 199 18 617 C2 were an accumulator and - separately - and an internal heat exchanger combined with the gas cooler, creating a very compact design was created. The accumulator is connected to a manifold of the gas cooler. The inner heat exchanger is located at the upper or lower edge of the gas cooler, ie parallel to the tubes, and thus directly in the influence of the cooling air, which has a temperature of about 30 - 40 ° C in summer, whereby the intended effect of the inner heat exchanger is counteracted , The degree of intended cooling of the refrigerant on the high pressure side is somewhat reduced by the relatively high temperature of the cooling air. The inner heat exchanger is also quite expensive to produce. Its connection with the gas cooler also seems to be structurally difficult to carry out.

From the JP 2002 31 0537A It is known to combine an intermediate heat exchanger with a receiver and attach to the manifold of another heat exchanger. The high-pressure side refrigerant collects there in the receiver and a line carrying the low-pressure side refrigerant passes through the receiver.

From the DE 199 44 950A1 It is known to form an intermediate heat exchanger as a tube-in-tube heat exchanger, whereby an accumulator chamber was also provided on the low-pressure side. The heat exchanger function of this construction can be improved.

The object of the invention is to propose with other design features comparable in terms of compactness and functionality device that can be produced cheaper.

The solution according to the invention results in the device according to the preamble of claim 1 by the features in its characterizing part.

Because, according to the invention, the container containing the tube is connected to the manifold of the heat exchanger, preferably the gas cooler, to a structural unit, wherein the accumulator chamber and the heat exchanger chamber present in the container extend parallel to the manifold and over a substantial portion of the length of the container achieved a good result in terms of compactness. At the same time, the favorable possibility of arranging a dryer and optionally also a filter in the accumulator chamber and / or the heat exchanger chamber of the container, since the space available for this measure is sufficient. The filter and dryer ensure the desired drying and cleaning (treatment) of the transcritical refrigerant, which can be CO2, for example.

The accumulator serves the functionality of the system, since it contributes to the fact that only vaporous refrigerant reaches the compressor and thereby ensures its proper operation.

This is not precluded that the vaporous refrigerant shortly before leaving the heat exchanger chamber in the direction of the compressor via an opening in the longitudinal wall small amounts of oil and liquid refrigerant are supplied. The refrigerant vapor is at this point in such a state that the supply of oil and liquid refrigerant further cooling by Evaporative cooling has the consequence. The vaporous state of the refrigerant at the compressor is thereby assisted and the refrigerant inlet temperature at the compressor is lowered again. In the above-mentioned prior art, the refrigerant must overcome a more or less large slope after the return of the oil, resulting in losses. According to the present invention, the recirculation is made bypassing the inner heat exchanger directly into the suction line, whereby a more favorable heat transfer is present.

The mentioned tube is preferably an extruded multi-chamber tube that extends substantially straight over at least a substantial length of the container, whereby u. a. the relatively inexpensive production of the device is effected. Preferably, the multi-chamber tube is covered around its entire circumference with the heat exchange rib.

A longitudinal wall is formed in the container, which divides the container into two parts, namely an accumulator chamber and a heat exchanger chamber. The longitudinal wall has at least one opening at one end to allow the refrigerant to flow from the accumulator chamber into the heat exchanger chamber. At the other end of the longitudinal wall, another opening is provided, via which accumulated in the accumulator oil can get into the refrigerant.

In the accumulator chamber, a drying agent and also a filter can be arranged. An inlet tube is disposed in the accumulator chamber to assist in the settling of any liquid refrigerant present in the low pressure phase. In or on the introduction tube, the dryer can be located and immediately below the filter can be arranged.

A plastic wall can be inserted into the container which suppresses the undesired heat transfer between the accumulator chamber and the heat exchanger chamber. The heat exchange should take place essentially in the heat exchanger chamber, since this was specially equipped for it. Overall, this results in slightly higher temperature differences between the low pressure side and the high pressure side in the heat exchange chamber itself, resulting in improved efficiency of heat exchange.

The device is characterized in that the container is designed as a slender, preferably produced by extrusion hollow body with a longitudinal wall or with holders for holding an inserted longitudinal wall, wherein the Longitudinal wall has at least one opening to flow the refrigerant from the accumulator chamber in the heat exchanger chamber, and that the tube is preferably made as a by the same extrusion process produced multi-chamber tube which extends through the heat exchanger chamber and is covered on all sides with heat exchange ribs. The device is particularly easy to manufacture and further distinguished by its slim design, which helps to accommodate a conventional air conditioning and transcritical refrigeration system, such as CO2, with substantially the same space requirements, which is a non-negligible benefit to automobile manufacturers. thus not forced to change their space concepts within a series of automobiles depending on the type of air conditioning. With global environmental regulations in mind, automobiles will want to equip one market with conventional air conditioning systems and another with CO2 air conditioning systems. Hereinafter, some embodiments will be described with reference to the accompanying drawings. This description includes other features and associated benefits that may prove particularly important.

Brief description of the pictures

The Fig. 1 shows a longitudinal section through a device according to the invention.

The Fig. 2 shows a cross section through the device according to the Fig. 1 or 3 ,

The Fig. 3 shows a longitudinal section in a preferred embodiment of the invention.

The Fig. 4 shows an alternative design in a cross section through the container. The Fig. 5 shows a flat multi-chamber tube in a cross section according to another alternative.

The Fig. 6 . 7 and 8th show different versions of the container in cross section. The Fig. 9-12 show purely schematically the connection of the device with a heat exchanger, preferably with the gas cooler.

The devices described in the exemplary embodiments are preferably intended for use in air conditioning systems of motor vehicles in an approximately vertical arrangement.

The apparatus for treating the refrigerant according to the Fig. 1 and 3 differs in the arrangement of a filter 23 in the accumulator 21 or in the heat exchanger chamber 22. They otherwise agree that they have a container 20 with a longitudinal wall 26 which was produced by extrusion molding. The longitudinal wall 26 divides the container 20 into the two mentioned chambers 21, 22 which extend in parallel and substantially over the entire length of the container 20. In the accumulator chamber 21 is a dryer 24, which was arranged outside of an insertion tube 25 in this embodiment. Through the heat exchanger chamber 22 extends a flat multi-chamber tube 10, which is equipped with a heat conducting rib 11 which largely fills the remaining cross section of the heat exchanger chamber 22 in order to achieve good results in terms of heat exchange efficiency can. Furthermore, an insulation 50 was provided in both embodiments, which covers the surface of the container 20 . This measure is particularly suitable where you would like to avoid temperature effects from the environment on the heat exchange in the container 20 . Usually these are too high outside temperatures. The lower-pressure side, cooler refrigerant flows through an opening 40 in the upper lid 80 into the accumulator chamber 21 a. In order to support the accumulator function or the settling of liquid and oil, an introduction tube 25 projects into the accumulator chamber 21 . In case of Fig. 1 This refrigerant flows through a filter basket 25 at the end of the introduction tube 25. Oil present in the refrigerant and residual liquid refrigerant settle in the accumulator chamber 21 at the bottom. The gaseous refrigerant flows above an inlet opening 31 in the longitudinal wall 26 in the heat exchanger chamber 22 to pass through the heat conducting rib 11 down in the direction of exit 41 , which is arranged in the wall of the container 20 . The high-pressure side and warmer refrigerant flows through a channel 70 in the upper lid 80 in the multi-chamber tube 10 , flows in the multi-chamber tube 10 down to the exit channel 71 in the lower lid 80, after heat release to the low-pressure side refrigerant and further cooled and therefore the performance-improving state of leaving the container 20 toward an expansion device (not shown) and the evaporator. Down in the longitudinal wall 26 is a channel 30 and a bore 32 to supply the low-pressure side refrigerant after passing through the heat exchanger chamber 22 in the accumulator 21 settled oil. ( Fig. 2 ) In the embodiment according to the Fig. 3 two flat filter elements 24 were provided. One of them was arranged in front of the channel 30 and the second is located in front of the already mentioned outlet 41 in the heat exchanger chamber 22. With this embodiment, it should be pointed out that the present invention with respect to the placement of such elements provides greater latitude for the designer than the prior art.

The Fig. 4 shows the cross section through the container 20 of another particularly notable embodiment. In some cases, a larger or specially designed accumulator chamber 21 is required, according to Fig. 4 has been achieved in that the flat multi-chamber tube 10 has been formed with a shape adapted to the contour of the container 20 shaping and thus extends along a portion of the container wall. Again, a longitudinal wall 26 was used, which is also adapted to the mentioned contour. On the inside of the container wall there are receiving grooves 27 into which the longitudinal edges of the longitudinal wall 26 can be inserted. The grooves 27 do not limit the manufacturability of the container 20 by means of extrusion molding, ie they can be realized by means of this method. The multi-chamber tube 10 is preferably, but not necessarily, also an extruded tube with, for example, two rows of apertures 12. More preferably, this design is then made when, as in the Fig. 5 is shown to be dispensed with the corrugated heat exchange ribs 11 as a single part by the multi-chamber tube 10 is equipped on the outside with rib-like channels. Here, according to a further development not shown, it is also possible to form the longitudinal wall 26 in one piece with the multi-chamber tube 10 , whereby the insertion of a longitudinal wall 26 and the requisite receiving grooves 27 or the like can be dispensed with. In this case all parts are made of metal, for example aluminum. However, it brings certain advantages already mentioned above for the heat exchange with it, when the longitudinal wall 26 is made of a material having a lower thermal conductivity, for example made of plastic, and used.

The Fig. 6 . 7 and 8th show further embodiments in cross-section through an extruded container 20 with two longitudinal walls 26, which then form three chambers or compartments in the container 20 . These chambers may be formed according to the desired application as a battery chamber 22 or as a heat exchanger chamber 21 . In the example according to the Fig. 6 was the middle chamber as a heat exchanger chamber 22 and the two other chambers formed as accumulator 21 . In the heat exchange chamber 22 is a multi-chamber tube 10 which with respect to the above Fig. 5 already described. The Fig. 7 shows another example in which all three chambers are designed as heat exchanger chambers 22 . By the reference numeral 90 , a design option has been pointed out, which is to partially increase the wall thickness of the container 20 to the cross-section of the chambers - while maintaining the circular cross-sectional shape of the container 20 - form such that the insertion of the tube 10 with the heat exchange fin 11 is facilitated. It can be used in this case conventional corrugated fins 11 , which are spirally wound around the tube 10 . In other cases, such a uniform cross-section also lends itself to the collecting chamber 21 Fig. 8 the "uniformed" cross-section was achieved by another measure, namely a slight deviation from the round shape of the container, which is still acceptable despite the high pressures in the system. As can be seen from the illustration, four graduations 60 distributed on the circumference of the container 20 have been provided, which result in that the cross section of the upper and the lower heat exchanger chamber 22 can be approximately rectangular. The middle chamber was designed here as an accumulator chamber 21 .

The device described so far has been as in the following Fig. 9-12 is shown combined with the gas cooler 3 in order to achieve a particularly compact design of the entire system. The container 20 may in principle be such as, for example, in the Fig. 3 shown and already described above.

As is customary in prior art air conditioning systems with two-phase refrigerant, the container 20 is arranged parallel to and connected to a header 30 of the condenser, here the gas cooler 3 . The difference further consists in that in the prior art it is only a collector, but in the present case an accumulator 21, combined with an internal heat exchanger 22, is connected to the gas cooler 3 . Specifically, in the illustrated embodiment, the container 20 is secured by means of two holders 5 on the manifold 4 . In the Fig. 9 the necessary components of the air conditioning circuit to the to have been - and Abströmstellen for the low-pressure side LP and the high-pressure side refrigerant HD indicated by appropriate labeling. The gas cooler 3 receives high temperature compressed gaseous HD refrigerant from the compressor, which is cooled in the gas cooler 3 by heat exchange with cooling air. The serpentine flow through the gas cooler 3 by groups of parallel flat tubes was indicated by arrows. In the headers 4 of the gas cooler 3 are partitions that cause the described flow. The HD - refrigerant into the heat exchanger chamber 22 occurs immediately after leaving the gas cooler 3, and indeed, as described in the extending through the chamber 22 multi-chamber tube 10th

In the Fig. 9 was provided to make the passage from the gas cooler 3 to the container 20 by means of a short line 6 from the manifold 4 in the multi-chamber tube 10 . As an alternative, the shows Fig. 12 a slightly more compact design, which consists in that the conduit 6 passes through one of the holder 5 and is connected to the multi-chamber tube 10 . The ND refrigerant coming from the evaporator is in the state of subcooling. It passes through the reaching in the accumulator 21 insertion tube 25 into the accumulator 21 a and passes the dryer 24 and a filter 23 at the end of the insertion tube 25. In contrast to the previously described embodiments, the opening of the oil in the longitudinal wall 26 directly in the area of the soil. At the upper end of the longitudinal wall 26, the inflow opening 31 is located for the gaseous ND refrigerant flowing into the heat exchange chamber 22 through the heat exchange fin 11, to flow out downward from the chamber 22 toward the compressor. It is enriched with oil and settled liquid refrigerant, which immediately goes into the gaseous state due to the heat absorbed in the heat exchanger and assumes a lower temperature, whereby the compressor is relieved. The Fig. 10 shows, also schematically, a section of a plan view of the device according to Fig. 9 ,

The Fig. 11 shows a further development idea, which consists in that the container 20 produced by extrusion has no integrated longitudinal wall 26 , but was equipped only with receiving grooves 40 . These receiving grooves 40 serve to be able to use a longitudinal wall made of plastic, which is otherwise formed as described. Such a design brings advantages in terms of the efficiency of the heat exchange, and it is executable despite the prevailing high pressure because it is between the Heat exchanger chamber 22 and the accumulator 21 are no significant pressure differences.

In the FIGS. 9 and 10 an additional plastic longitudinal wall was added directly to the metal longitudinal wall 26 , as indicated by the two parallel lines.

The container 20 of the proposed device is also characterized by its slim design. The ratio of its length L to its diameter D is at least 3: 1, preferably the ratio is about 6: 1.

Claims (19)

1. Device for the treatment of the refrigerant which circulates in a transcritical air-conditioning circuit, containing: a compressor (1), gas cooler (3), evaporator and expansion member, and at the same time runs through a high-pressure side and low-pressure side, in which the refrigerant has a different temperature, the device comprising a flat multi-chamber tube (10), through which one side flows and which is arranged in a container (20) through which the other side flows, in order to serve as an intermediate heat exchanger, an accumulator chamber (21), a heat exchanger chamber (22) and, between them, a wall being formed in the container (20), characterized in that the container (20) containing the multi-chamber tube (10) is connected to a header tube (4) of the gas cooler (3) to form a structural unit, a longitudinal wall (26), the accumulator chamber (21) and the heat exchanger chamber (22) extending in parallel with and at least over a substantial portion of the length of the narrow container (20), the high-pressure-side refrigerant, immediately after it leaves the gas cooler, entering the flat, essentially non-deformed multi-chamber tube (10) which extends through the heat exchanger chamber (22), and flowing through the said multi-chamber tube, and the gaseous low-pressure-side refrigerant flowing through the accumulator chamber (21) into the heat exchanger chamber (22) and through a heat exchange rib (11) which approximately fills the remaining cross section of the heat exchanger chamber (22).
2. Device according to Claim 1, characterized in that an introduction tube (25) for the low-pressure side is arranged in the accumulator chamber (21).
3. Device according to Claim 2, characterized in that a dryer (24) is arranged in or on the introduction tube (25).
4. Device according to one of the preceding claims, characterized in that at least one inflow orifice (31) is present at one end of the longitudinal wall (26), in order to bring the low-pressure side out of the accumulator chamber (21) into the heat exchanger chamber (22) of the container (20).
5. Device according to one of the preceding claims, characterized in that at least one orifice (32) for oil contained in the refrigerant is present at the other end of the longitudinal wall (26).
6. Device according to Claim 4 or 5, characterized in that the longitudinal wall (26) is preferably arranged outside the mid-plane of the container (20), so that the accumulator chamber (21) is larger than the heat exchanger chamber (22).
7. Device according to one of the preceding claims, characterized in that the heat exchanger chamber (22) located inside the container (20) extends around a part-radius of the latter.
8. Device according to one of the preceding claims, characterized in that the container (20) and the flat multi-chamber tube (10) are produced by the extrusion method.
9. Device according to one of the preceding claims, characterized in that the container (20) with longitudinal wall (26) is a tube which is produced by the extrusion method and the ends of which are closed by covers (80).
10. Device according to one of the preceding claims, characterized in that an insulating plate or the like is arranged adjacently to the longitudinal wall (26).
11. Device according to one of the preceding claims 1-8, characterized in that, instead of the longitudinal wall, an insulating plate can be inserted into the tube.
12. Device according to Claim 11, characterized in that grooves or similar receptacles (27), into which the insulating plate can be inserted, are integrally formed on opposite sides of the tube wall.
13. Device according to one of the preceding claims, characterized in that the container (20) is shielded with respect to the cooling-air stream flowing through the heat exchanger, preferably through the gas cooler.
14. Device according to one of the preceding claims, characterized in that the header tube (4) of the gas cooler and the container (20) are arranged at a slight distance from one another.
15. Device according to one of the preceding claims, characterized in that the container (20) is arranged behind an air guide plate in the air flow direction.
16. Device according to one of Claims 1-15, characterized in that the container (20) is provided on its outside at least partially with insulation (50).
17. Device according to one of the preceding claims, characterized in that one or more filters (23) for treating the refrigerant is or are provided in the container (20).
18. Device according to one of the preceding claims, characterized in that the multi-chamber tube (10), including the heat conduction ribs (11), can be produced as an extruded product.
19. Device according to one of the preceding claims, characterized in that the ratio of the length (L) to the diameter (D) of the container (20) is ≥ 3:1.

Images