Heat Exchanger with Ventilation

The invention relates to a heat exchanger for at least one heat transport medium, as is used, for example, as a radiator for heating air flowing into the interior of a motor vehicle. The invention furthermore relates to a coolant circuit and to an air treatment device for vehicles using a heat exchanger of this type.

Heat exchangers are used, inter alia in motor vehicles, for different tasks. For example, heat exchangers for cooling the engine are used in a further sense, for example as coolant coolers, oil coolers, exhaust gas coolers and charge air coolers. A further customary field of use of heat exchangers in motor vehicles is the controlling of the temperature of the air supplied to the passenger compartment. Use is made here of heat exchangers, for example in the form of evaporators, condensers (or gas coolers), internal heat exchangers and radiators.

Currently, heat exchangers of this type exist in very different structural forms and types of installation. If at least one at least partially liquid heat transport medium is used in heat exchangers, as is the case, for example in coolant coolers or radiators, the problem may arise of accumulations of air in the heat exchanger which may possibly have a negative effect on the flow rate or the uniform distribution of the heat transport medium in the heat exchanger. This applies in particular in the case of heat exchangers which are installed upright.

In order to ensure a high flow rate, which is as uniform as possible, of the heat transport medium, it may therefore prove necessary to remove air which may accumulate in the heat exchanger. Different procedures have hitherto been used for this.

One possibility is to set up the heat exchanger, for example by means of a flat installation position or a corresponding arrangement of feed and return openings, in such a manner that air accumulating in the heat exchanger can escape from the heat exchanger or, for example when the system is at a standstill, does not accumulate at all. One problem with heat exchangers set up in such a manner is that certain types of installation (such as, for example, an upright installation of the heat exchanger) or certain designs of the supply openings for the heat transport medium are de facto excluded. However, particularly in the case of motor vehicles, this is often problematic, since the construction space in the front part of the motor vehicle generally has very constricted dimensions and certain configurations of the heat exchanger are sometimes unavoidable because of the other engine compartment subassemblies.

A further solution possibility is to permit a certain degree of accumulations of air in the heat exchanger and to trust that, at a certain flow rate of heat transport medium, the accumulations of gas in the heat exchanger will be carried along by the heat transport medium through the heat exchanger. A problem with this is that, in particular at low flow rates of heat transport medium, the effectiveness of the heat exchanger may be reduced by the accumulation of air both as seen from the aspect of absolute power and from the uniformity of the heat output. The latter, in particular, may lead to thermal distortions and, especially because of the non-uniform distribution of heat to the radiator surface, may be disadvantageous when treating air for the passenger compartment. A further problem is that, because of the accumulations of gas, the radiators have a tendency to form noise, which is disadvantageous especially with components arranged in the vehicle interior (such as, for example, in the case of the radiator of an air-conditioning system).

Finally, it has already been separately proposed to provide small ventilation openings adjacent to the return such that gas accumulating in the heat exchanger can pass through said ventilation openings and can therefore leave the heat exchanger. However, such ventilation openings may often only partially ventilate the heat exchanger. Furthermore, such ventilation openings have a tendency to form noise, which is disadvantageous in particular in the case of heat exchangers (such as, for example, radiators) which are arranged in the vehicle interior or adjacent to the vehicle interior.

The present invention therefore sets itself the object of developing a heat exchanger with at least one ventilation device in such a manner that the known problems with heat exchangers known from the prior art are at least partially eliminated or at least reduced. In particular, the invention makes it the object to propose a heat exchanger which is simple and cost-effective to construct and produce and nevertheless permits as extensive ventilation as possible without an excess amount of undesirable noises occurring.

These objects are achieved by the devices according to the independent claims.

It is proposed to develop a heat exchanger for at least one heat transport medium, with at least one feed, at least one return and at least one ventilation device, to the effect that the ventilation device is arranged at a distance from at least one return opening in the heat exchanger. It has surprisingly been shown that such an arrangement of the ventilation device can ensure particularly advantageous ventilation of the heat exchanger. It has hitherto been assumed that an arrangement of the ventilation devices in the direct vicinity of the return is advantageous, since the accumulations of gas can be particularly effectively sucked off as a result. However, this is unexpectedly not the case, since often accumulations of gas can also form which are located at a distance from the return of the heat exchanger. The proposed arrangement of the ventilation device can make it possible for even such accumulations of gas to be effectively removed. It is advantageous if at least one ventilation device is provided in each case at least in the regions in which a particularly large accumulation of gas occurs.

It is preferable also to form the ventilation device at a distance from at least one feed opening in the heat exchanger. In this proposed embodiment, in addition to the actual passage of the heat transport medium through the heat exchanger, a type of additional “ventilation circuit” can be provided especially in the upper part of the radiator, said ventilation circuit running, in particular, through the critical regions of the heat exchanger and, as a result, being able to particularly effectively ventilate the heat exchanger. Of course, care has to be taken here to ensure that a relatively low flow rate is selected for this additional ventilation circuit such that the efficiency of the heat exchanger does not substantially decrease.

It is proposed that the distance between at least one ventilation device and at least one feed opening and/or between at least one ventilation device and at least one return opening is at least 10 mm, preferably at least 15 mm, particularly preferably at least 20 mm and, in particular, at least 25 mm. The proposed values have proven favorable. However, other numerical values are also conceivable. In particular—even with other figures occurring in this specification—in the case of (semi-)intervals and discrete values, all of the numerical values are to be regarded as disclosed and usable as desired.

It furthermore proves advantageous if at least one feed opening and at least one return opening are arranged adjacent to each other. This can ensure a compact construction and a simple installation, but also particularly effective ventilation.

Furthermore, it has proven advantageous if at least one ventilation device is arranged at a distance from the direct connecting section between at least one feed opening and at least one return opening. In particular, it may prove advantageous if the ventilation device is arranged as far as possible away from the direct connecting section between feed opening and return opening. With the aid of the proposed embodiment, it is possible to allow the “ventilation circuit” already mentioned to flow through most of or essentially through the entire region of the heat exchanger in which accumulations of gas can form, with the result that particularly effective ventilation is promoted.

It has been shown that the invention can be used particularly advantageously with heat exchangers which are arranged upright and have, advantageously, at least one coolant tank preferably located at the top. In particular in the case of heat exchangers of this type, accumulations of gas easily occur and, with the use of the present invention, they can be particularly effectively eliminated.

It has furthermore been shown that the invention is particularly effective in conjunction with heat exchangers which have a bottom depth deflection and/or are designed as radiators. A bottom depth deflection is a “deflection” of the heat transport medium taking place at the bottom at depth. The “depth” refers to the throughflow direction of the second fluid, such as, in particular, air to be heated for a vehicle interior.

A particularly advantageous development of the proposed invention arises if at least one ventilation device is designed in the form of one or more openings.

The openings can be configured, in particular, as recesses and are preferably formed in a heat exchanger partition which is customarily present in any case, preferably in an upper region of a partition. One or two openings, possibly also three, four, five or even more openings, have proven advantageous. The openings can have any desired shape. Recesses which are circular, semicircular, lenticular, square, rectangular, concave, semi-lenticular and/or slot-like (in each case guided horizontally, vertically and/or obliquely) have proven worthwhile. Dimensions of up to 5 mm, preferably 1 to 4 mm, particularly preferably 2 to 3 mm, have proven worthwhile as typical sizes. However, in particular in the case of slots, lengths of 5 to 15 mm, preferably 6 to 12 mm, in particular 8 to 10 mm, may also prove favorable.

It is also possible to design the openings as a molded configuration which is advantageously formed in a coolant tank, preferably in a coolant tank located at the top of the heat exchanger. The openings are particularly preferably provided in a contact region between partition and coolant tank wall, in particular in a region located at the top of the coolant tank. The opening may also be located in the region of an optionally present connecting seam of the coolant tank. By means of this design, it is possible that manufacturing steps can be saved and possible unnecessary material loadings can be reduced. Of course, a combination of an opening designed as a molded configuration and an opening designed as a recess is also possible, in particular when said openings lie adjacent to each other in such a manner that the entire opening cross section is enlarged.

A further advantageous constructional form can be produced if at least one ventilation device has at least one flow-limiting means which is designed, in particular, as a baffle, as a tube, as an integrally formed flange and/or as a hydrodynamic flow-limiting means. Very generally, the proposed radiators, at least in regions in which accumulations of gas may occur, should not, as far as possible, have any sharp edges and other constructional geometries which may lead to undesirable noises. The proposed development can also make it possible to reduce the noises further by it being possible for the flows which occur to be reduced in particular in terms of velocity and/or flow rate. A hydrodynamic flow-limiting means is understood quite generally as meaning means in which a hydrodynamic banking-up pressure of the heat transport medium flowing through the heat exchanger is used in order to limit other flow paths, in particular of the material flowing through the ventilation devices.

Furthermore, it may prove advantageous to design at least one ventilation device as an external ventilation device outside the heat exchanger body and/or the coolant tank. The ventilation device here can be arranged, for example, as far as possible away from the passenger compartment or in regions in which only few noises occur or the noises which occur are transmitted only to a reduced extent into the motor vehicle interior.

It is conceivable in this connection to provide at least one external ventilation device in a flange region which is optionally formed separately. Said flange region can be provided in the feed or return line, for example at a certain distance from the heat exchanger. In the case of radiators, this distance between flange and radiator—and therefore the distance of the ventilation device from the radiator—is generally relatively small, and is customarily 10-50 mm, for example 10 mm, 15 mm, 20 mm, 25 mm, 30 mm, 40 mm or 50 mm.

Furthermore, it is proposed to provide a coolant circuit with at least one heat exchanger in accordance with one of the proposed embodiments. The coolant circuit has the corresponding advantages in analogous form.

It is also proposed to provide an air treatment device for motor vehicles with at least one heat exchanger in accordance with one of the abovementioned embodiments. The air treatment device, which can additionally have, for example, an evaporator for cooling inflowing air, then has the described advantages in analogous form.

Furthermore, it is advantageous to develop a heat exchanger, a coolant circuit or an air treatment device according to one of the above-described embodiment possibilities to the effect that at least one ventilation device is formed with respect to at least one subassembly of the heat transport medium circuit and/or with respect to the entire heat transport medium circuit in the region of a location which is mounted at a geodetically locally high point and/or essentially in the region of the location mounted at the geodetically highest point. The proposed device can be formed particularly effectively in this case.

The invention is explained in more detail with reference to preferred exemplary embodiments and with reference to the attached figures, in which:

FIG. 1 shows a radiator for heating a motor vehicle interior in a perspective view;

FIG. 2 shows a schematic cross section through the radiator shown in FIG. 1;

FIGS. 3A and 3B show possible radiator flat tubes in cross section;

FIGS. 4A to 4L show exemplary embodiments of partitions with different ventilation openings in plan view;

FIG. 5 shows a baffle for a ventilation device in cross section;

FIGS. 6A and 6B show a nose portion with a ventilation device in a schematic view and in cross section;

FIG. 7 shows a further embodiment of a ventilation device;

FIG. 8 shows part of a heating circuit with radiator and external ventilation device in a schematic view;

FIG. 9 shows a schematic cross section through a coolant tank provided with a molded configuration.

FIG. 1 illustrates a radiator 1, which is known per se, for heating air which, in the present case, is supplied to a motor vehicle interior. The direction of flow of the air is indicated schematically in FIG. 1 by an arrow A. The air flow can be guided in any desired manner in a cross parallel flow or in a cross counterflow. The radiator 1 illustrated is a “bottom depth radiator” which is arranged upright. At its upper end 2 and at its lower end 3, the radiator 1 has a respective coolant tank 4, 5 which serves at the same time as a collecting tube for the coolant flowing through it. The upper coolant tank 4 is divided by a partition 6 (indicated schematically) into a front region 7 at the front adjacent to the feed 9 and a rear region 8 at the back which has the return 10.

A plurality of coolant tubes, in the present case designed as flat tubes 11, are formed between the upper coolant tank 4 and the lower coolant tank 5. Respective corrugated fins 12 which improve the transfer of heat to the air A flowing through are located between the flat tubes 11. The corrugated fins 12 can be provided with texturing in a manner known per se in order to improve the transfer of heat to the air A flowing through.

FIG. 2 illustrates, schematically in cross section, the radiator 1 illustrated in FIG. 1, in order to explain in more detail the route of the coolant flowing through the radiator 1.

On the front side 13 of the radiator 1, the coolant flows at the feed 9 via a feed opening 15 into the front part 7 of the upper coolant tank 4. As already explained, the coolant tank 4 has a partition 6 which separates the coolant tank 4 into a front region 7 and a rear region 8. Starting from the front region 7, the coolant flows along the arrow direction B through regions, located at the front 13, of the flat tubes 11 in the direction of the lower side 3 of the radiator 1. The flat tubes 11 are designed—as explained in more detail below—in such a manner that, in the region of the flat tubes 11, essentially no flow takes place transversely with respect to the longitudinal extent of the flat tubes 11. At the lower end 3 of the radiator 1, the coolant emerges from the front part 13 of the flat tubes 11 into the lower coolant tank 5. In this coolant tank 5, the coolant is deflected at the “depth” C and enters the rear region 14 of the flat tubes 11 where it flows in the opposite direction D upward 2 to the upper coolant tank 4. The course of the flow is indicated by arrows C, D. After the coolant from the rear region 14 of the flat tubes 11 has been released into the rear part 8 of the coolant tank 4, it finally emerges via the return opening 16 out of the radiator 1 and is guided via the return 10 to the other components of the coolant circuit (not illustrated specifically in the present case).

FIGS. 3A and 3B illustrate, for the sake of completeness, possible embodiments of flat tubes 11 as can be used for the radiator 1 shown in FIGS. 1 and 2. The flat tube 11 illustrated in FIG. 3A has a plurality of passages 17 for the coolant and can be produced, for example, by means of extrusion.

The flat tube 11 shown in FIG. 3B can be produced, for example, by bending or forming and subsequent welding or soldering of a solder-plated flat material. This flat tube 11 is divided by a central web 19 into two chambers 18 separated from each other.

Gas bubbles can accumulate, especially in the upper region 2 of the upper coolant tank 4, for example after a prolonged shut-down phase or else during the operation of a heat exchanger, such as the radiator 1 shown in FIGS. 1 and 2. Without corresponding ventilation devices, in particular gas bubbles which form in the front part 7 of the coolant tank 4, which part faces the feed 9, are not removed or are scarcely removed from this front region 7 of the upper coolant tank 4. The gas bubbles may interfere with the operation of the radiator 1. The flow cross section for the coolant flowing through in the front region 7 of the upper coolant tank 4 may firstly be constricted for the coolant flowing through, and therefore the heating power of the radiator 1 can decrease. Furthermore, a different distribution of heat along the radiator surface 20 may occur, which accordingly leads to different heating of the air A flowing through, which is correspondingly disadvantageous.

In order to remove the gas bubbles accumulating in the upper coolant tank 4, suitable ventilation devices are therefore to be provided.

A plurality of suitable partitions 6 which are provided with corresponding ventilation devices are illustrated in FIG. 4.

First of all, FIG. 4A illustrates a partition 6 which is of continuous design and can be used, for example, in conjunction with an external ventilation device 21 (see FIG. 8). By contrast, in the case of the exemplary embodiments of partitions 6 according to FIGS. 4B to 4L, the ventilation device is designed in each case in the form of a differently designed recess 22.

In FIGS. 4B to 4E, the recesses 22 are designed as round, half round, oval or semi-oval recesses 22. Even if the figures each only illustrate a single recess 22, it is also possible for a plurality of recesses which are preferably arranged along the upper edge of the partition 6 to be provided. Diameters of 1, 2, 3 or 4 mm (round or half-round) or 1, 2 or 3 mm for the shorter axis and 2, 3, 4 mm for the longer axis (oval or semi-oval) are appropriate typical dimensions.

In FIGS. 4F and 4G, a rectangular and square recess 22 are provided. Also in this case—described in the case of round, half-round, oval or semi-oval recesses—a plurality of recesses 22 can be provided, with it also being possible for different shapes to be mixed. This also includes, of course, the following exemplary embodiments. 1, 2, 3 or 4 mm are typical appropriate dimensions for the longitudinal sides.

Of course, in this connection, n-cornered recesses, in particular triangles, with differing position and orientation are also conceivable. However, in particular the values 5, 6, 7, 8, 9 and 10 have proven worthwhile for the number of corners. The n-corners can be not only regular (equal-angled) n-corners, but also any desired, general n-corners.

In FIG. 4H, the recess is designed as a concave, lenticular formation 22 which can be formed particularly preferably in the radius region of the partition. The radius of the lens preferably corresponds essentially to the radius of the partition. However, other radii—even a straight line in an extreme case—are also conceivable in this connection.

It is also possible, as illustrated in FIGS. 4I and 4J, that only part of the lens according to FIG. 4H is detached from the partition 6 and, for example, only the lower half (FIG. 4I) or the upper half (FIG. 4J) is removed.

Very generally, use can advantageously also be made of shapes which are composed of straight lines and/or optionally a plurality of curves with the same, different and also changing radius, and are provided in a different number and in different orientations.

Of course, slot-shaped recesses are also possible, as indicated in FIGS. 4K and 4L. 1, 2, 3 or 4 mm is appropriate as the slot width, and 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12 mm as the length. The angle of 45° shown in FIG. 4K may also, of course, assume different values.

Quite generally, a value of 1, 2, 3, 4 or 5 has proven particularly worthwhile for the number of openings. Of course, the partitions 6 which are provided with openings 22 may also be combined with external ventilation devices 21. It is also possible to combine different opening shapes 22 with one another.

FIG. 9 illustrates a ventilation device which is designed as a molded configuration 37 in the upper wall 39 of the upper coolant tank 4. The molded configuration 37 can be produced, for example, by deformation of the wall 39. An opening 38 between the partition 6 and the upper wall 39 of the coolant tank 4 is located in the region of the molded configuration 37. On account of the opening 38, there is a connection between the front region 7 and rear region 8 through which accumulating gas bubbles can be removed.

The abovementioned, preferred dimensioning proposals can be used in an analogous manner for the dimensioning of the molded configuration 37 and of the opening, produced by the latter, between coolant tank wall 39 and partition 6.

In the exemplary embodiment illustrated in FIG. 9, the partition 6 does not have a recess in the region of the molded configuration 37 of the upper wall 39 of the coolant tank 4. Of course, it is also possible, in this region, to provide an additional opening in the partition 6.

FIG. 5 illustrates a flow-limiting device, which is designed in the present case as a baffle 23. A strip material 25, which runs parallel to the partition 6 and is held, for example, via a retaining web 24, is arranged in the region of an opening 22 formed in the partition 6. It is also possible for side walls (not illustrated here) to be arranged in one or in both side regions of the baffle 23, thus resulting in an overall trough-like design of the baffle 23. It is pointed out that the baffle 23, in particular if it is arranged in the rear region 8 of the upper coolant tank 4, can also use a hydrodynamic back pressure. The latter is produced by the flow which emerges from the flat tubes 11 and is indicated by an arrow E. An advantage of said flow E is that it depends on the flow rate of coolant through the radiator 1. In the case of a large flow rate 1 of coolant, a relatively high difference in pressure is produced between feed 9 and return 10 and therefore between front part 7 and rear part 8 of the upper coolant tank 4, which would result in a correspondingly high flow rate through the recess 22. This high flow rate can be reduced by the hydrodynamic effect described. In every case, the flow rate through the recess 22 can be reduced with the aid of the baffle 23 and therefore, in particular, the velocity of gas and/or coolant passing through can be reduced. This may, in particular, have a noise-reducing effect.

FIG. 6A, 6B illustrate a further flow-limiting device in the form of a flange or projection 26, at the lower end 27 of which a ventilation device 28 is formed. Advantages can also arise here, in particular on account of the above-described hydrodynamic effect which may occur. Furthermore, the projection 26 can optionally be produced in a particularly simple and cost-effective manner by shaping the material of the partition 6 by deformation.

FIG. 7 shows a further conceivable embodiment of a flow-limiting device in the form of a tube 29 provided with a centrally arranged recess (not visible in the figure). In the present case, the tube 29 is bent in the form of a “twisted S”, and therefore the entry 31 of the tube 29 runs horizontally, while by contrast the exit 32 of the tube 29 runs vertically, such that hydrodynamic effects can be used particularly advantageously. A retaining web 30 for the tube 29 can be provided for stabilization purposes.

Finally, FIG. 8 outlines a further part of a cooling circuit in which an external ventilation device 21 is provided which, in the present case, is arranged at the (optionally locally) highest location 33 of the cooling circuit. The radiator 1 can be designed in any desired manner with inner ventilation devices (for example according to FIGS. 4B to 4L) or without inner ventilation devices (according to FIG. 4A). In the exemplary embodiment illustrated in the present case, the external ventilation device 21 has a thin connecting channel 36 which connects the feed line 34 to the return line 35.

However—as customary in radiators—the flange may also be arranged at a shorter distance, such as, for example, at a distance of 10-50 mm, from the radiator. If appropriate, the flange may also be integrated in the radiator. Generally, only the distance between feed opening and/or return opening 15, 16 and the connecting channel 36 is essential.

Heat Exchanger with Ventilation

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