EP3521583B1 - Cooling device with at least two cooling circuits and a cooled supply line - Google Patents

Description

The invention relates to a cooling device with at least two cooling circuits which are connected to a common expansion tank for coolant. In particular, a cooling device with at least two cooling circuits that work at different temperature levels. The invention also relates to a vehicle, preferably a utility vehicle, and / or a stationary system with such a cooling device.

Cooling circuits are used to remove excess heat from self-heating or externally heated components. Driven by one or more coolant pumps, a coolant, e.g. oil, water or a water-cooling water additive mixture, circulates in a pipe and / or hose system in order to absorb heat from said components and then release it by means of a coolant cooler, e.g. to the Ambient air.

In the area of large-scale systems or in the vehicle area, several cooling circuits can often be provided, in particular several cooling circuits that operate at different temperature levels. For example, in hybrid vehicles it is customary to use a high-temperature circuit for cooling the internal combustion engine with a high temperature level of over 90 ° C. in normal operation and a low-temperature circuit for cooling the electric drive system with a low temperature level. It is also common, for example, in vehicles with indirect charge air cooling to use a high-temperature circuit to cool the internal combustion engine with a high temperature level of over 90 ° C in normal operation and a low-temperature circuit to cool the charge air at a low temperature level.

For a good and, in particular, efficient cooling performance of such cooling circuits, it is relevant that they are vented as completely as possible. This means that when the cooling circuit is filled, any air that may be present there can be displaced as completely as possible by the coolant and diverted away, and that gases produced by evaporation processes can be safely removed during operation. As a rule, this venting takes place via expansion tanks, which are connected to the corresponding cooling system by means of a vent line. In addition, expansion tanks have the task of providing a thermal to compensate for the expansion of the coolant, especially during operation. For this purpose, expansion tanks are partially filled with air, which is compressed when the coolant expands. The coolant that has accumulated in the expansion tank is returned to the corresponding cooling circuit via a filling line that connects the expansion tank with the corresponding cooling circuit. The documents are an example in this context DE 199 12 138 A1 , DE 10 2007 052 927 A1 , WO 03/042516 A2 and DE 10 2007 054 855 A1 referenced, all of which show such expansion tanks connected to several cooling circuits.

If, for reasons of cost and / or to make filling easier and / or for reasons of installation space, a common expansion tank is provided for several cooling circuits operating at different temperature levels, the different temperature coolants can be mixed in the expansion tank. Via the corresponding filling line, warmer coolant would then be introduced from the common expansion tank into a cooling circuit with a lower temperature level, which could restrict its functionality or lead to damage to the components contained therein.

In addition to the correspondingly larger dimensioning of the cooling circuit with a low temperature level, in order to better dissipate the additionally introduced amount of heat, the approach is also known in the prior art to modify the expansion tank in such a way as to avoid mixing of the coolants. For example, the laid-open specification discloses DE 2 063 298 A1 a common expansion tank for a motor vehicle with two separate cooling circuits, which has an absolutely tight partition. As a result, two separate areas for receiving coolant of a cooling circuit are formed and there is no exchange of coolant between the cooling circuits. However, this approach does not allow pressure equalization between the various cooling circuits and makes it more difficult to fill or introduce additives into the coolant, since all components (nozzles, silicate depot, etc.) have to be designed several times.

Instead of modifying the expansion tank, the prior art also uses the approach of mixing the coolant in the various cooling circuits and thus allowing the temperature levels to be adjusted in the common expansion tank, but precooling the coolant at a lower temperature level before it enters the cooling circuit. The laid-open specification discloses this DE 10 2015 212 554 A1 a motor vehicle with two Cooling circuits at different temperature levels, in which the coolant in the filling line is passed through a heat exchanger at a lower temperature before entering the cooling circuit. In the heat exchanger, heat is transferred from the coolant, which flows in the filling line from the expansion tank to the cooling circuit, to the coolant, which is in the The vent line from the cooling circuit to the expansion tank flows. Since the media flowing through the heat exchanger are therefore coolants in both cases, only a low cooling capacity is achieved due to the relatively small temperature difference between the two media. In addition, there is an undesirable introduction of heat into the overall system.

It is therefore an object of the invention to provide a device that is improved compared to the prior art in order to avoid the introduction of large amounts of heat into a cooling circuit which is in contact via a filling line with a common expansion tank used by several cooling circuits.

This object is achieved by a device with the features of the independent claim. Advantageous embodiments and applications of the invention emerge from the dependent claims and are explained in more detail in the following description with partial reference to the figures.

A basic idea of the invention is to use an air-cooled heat exchanger for cooling the filling line, which achieves a higher cooling capacity due to the higher temperature difference between ambient air and coolant, and to integrate this heat exchanger into existing components of the cooling circuit in a space-saving manner.

According to the invention, a cooling device with at least two cooling circuits is provided for this purpose, each of which is connected to a common expansion tank for coolant via at least one ventilation line and at least one filling line. Two of the cooling circuits preferably work at different temperature levels. An air-cooled heat exchanger is provided on at least one of the filling lines, by means of which the coolant is precooled before it enters the cooling circuit assigned to this filling line. The air-cooled heat exchanger can be provided at any point on the filling line, preferably in a central area of the filling line. This means that coolant can first enter a first area of the filling line, then pass through the air-cooled heat exchanger, then flow through a second area of the filling line until it finally enters the cooling circuit.

The term “cooling circuit” can be understood in this context to mean that it consists of a system connected via corresponding pipes, hoses or lines comprises several coolant pumps, coolant coolers and heat exchangers, in which coolant, preferably water, oil or a water-cooling water additive mixture, driven by the coolant pump, circulates almost closed. According to this design, the existing filling lines, expansion tanks and ventilation lines are primarily not understood as part of the cooling circuit. The cooling circuit preferably absorbs excess heat from self-heating or externally heated components, such as an internal combustion engine, electric motor or battery, via the heat exchanger and releases it to the ambient air by means of the coolant cooler.

A ventilation line is understood to be a fluid line, e.g. a pipe or hose connection, which connects a cooling circuit, preferably at its geodetically highest point, with the expansion tank, which is preferably arranged at an even higher level. Gases, vapors, expanding coolant and / or a coolant-air mixture can be conveyed from the cooling circuit to the expansion tank via the vent line. In other words, the diverted coolant is mainly transported from the cooling circuit to the expansion tank in the vent line. The vent line can consist of a plastic, metal or other suitable material.

Expansion tanks for coolants are known per se in the prior art and are used, on the one hand, to vent a cooling circuit. In addition, they can compensate for thermally induced changes in the volume of the coolant in a cooling circuit by temporarily storing expanding and thus excess coolant there. For this purpose, an expansion tank can have a coolant reservoir in the form of one or more coolant chambers for receiving the expanding coolant. The expansion tank can comprise an overpressure and / or underpressure valve for pressure regulation as well as a filler opening for coolant with an associated closure cap. Furthermore, the expansion tank can comprise devices for introducing additives into the coolant, for example a silicate deposit.

A filling line is understood to be a fluid line, for example a pipe or hose connection, which leads from the expansion tank, preferably from a geodetically lower area of the expansion tank, back to the, preferably lower lying, cooling circuit. The filling line is used to guide the coolant that has accumulated in the expansion tank back into the cooling circuit, whereby the substance transport in the filling line mainly takes place from the expansion tank to the cooling circuit. The cooling circuit is also preferably filled for the first time or re-filled with coolant via the filling line. The filling line can be turned off a plastic, metal or other suitable material and preferably flows into the cooling circuit at a point shortly before, ie upstream, the coolant pump.

As already mentioned, according to the invention at least two, preferably differently tempered, cooling circuits are each connected to a common expansion tank for coolant via at least one vent line and at least one filling line. However, it can also be provided that all cooling circuits connected to the common expansion tank operate at almost the same temperature level. In addition, further cooling circuits with their own expansion tanks, filling and venting lines can also be present in the cooling device. The exact structural embodiment of the expansion tank (s) is not relevant for the device according to the invention. Thus, the expansion tank can be designed in one piece or in several parts and comprise one or more coolant chambers. The coolant chambers can be connected via through openings and thus enable the coolant of the different cooling circuits to be mixed, or they can be separated from one another by tight partition walls, so that there can be no exchange of coolant between the different cooling circuits in the expansion tank. However, the invention is particularly advantageous if several cooling circuits at different temperatures are connected to an expansion tank and the coolant flows are mixed there. To prevent the associated introduction of "too warm" coolant from the common expansion tank into a cooling circuit with a lower temperature level, an air-cooled heat exchanger is provided, preferably on the filling line of the cooling circuit with a lower temperature level, which pre-cools the coolant before it enters the cooling circuit .

The air-cooled heat exchanger can be designed in a form known per se in the prior art, the heat extracted from the coolant being released to the ambient air at the end. For example, the air-cooled heat exchanger can be a tube bundle cooler or a tube cooler. The air-cooled heat exchanger can also include cooling fins and / or heat sinks. Since the operating temperature of the cooling circuits in common applications, e.g. in the automotive sector, is usually well above the ambient air temperature - for example, the temperature of a cooling circuit of an internal combustion engine in normal operation is> 90 ° C - the use of air as the heat exchange medium advantageously results in a high temperature difference and thus achieves a high cooling capacity.

In order to integrate the air-cooled heat exchanger into the existing installation space, according to the invention the air-cooled heat exchanger is designed as a first sub-area of a coolant cooler, which is separated from a second sub-area of the coolant cooler. Both the first and the second sub-area have their own inlet and outlet for coolant. The coolant cooler can be designed in a form known per se in the prior art, for example as a downdraft or cross-flow cooler. The coolant cooler can comprise a plurality of cooling passages or cooling tubes that are cooled by the ambient air flowing past. The term separated is to be understood in such a way that the two areas within the coolant cooler are not fluidically connected on the coolant side. This means that there is no exchange of coolant between the two areas within the coolant cooler. The separation can be achieved by means of partitions or ribs. Overall, the coolant cooler, understood as a component, can thus assume a double function. On the one hand, a partial area of the coolant cooler is used to cool coolant before it enters the cooling circuit. On the other hand, a partial area of the coolant cooler is used to cool the coolant that circulates in the cooling circuit. Furthermore, the volumes of the two areas of the coolant cooler outside the coolant cooler can be fluidically connected via corresponding lines or the expansion tank. That is to say, coolant can first pass through the first area of the coolant cooler, then enter the cooling circuit and, in the course of the circulation, get there into the second area of the coolant cooler. However, there cannot be any fluidic connection between the two areas of the coolant cooler, that is, neither inside nor outside of the coolant cooler.

A further development of the embodiment provides that the coolant cooler comprises a plurality of tubes, preferably flat tubes. Of these pipes, a first subset is assigned to the first sub-area and a second subset is assigned to the second sub-area, the two pipe sub-sets in the coolant cooler not being fluidically connected and the first sub-set being smaller than the second sub-set. For example, the coolant cooler can be designed as a downdraft or cross-flow cooler and can comprise a soldered cooler network consisting of a plurality of flat tubes and cooling fins. A small portion of these flat tubes can be used to cool the coolant in the filling line, while the remaining flat tubes of the coolant cooler are used to cool the coolant in the cooling circuit. For example, 10% of the tubes can be used to cool the filling line and the remaining 90% of the tubes can be used to cool the coolant circulating in the cooling circuit. The advantage of this embodiment is that a coolant cooler required for the proper functioning of the cooling circuit can be expanded to the dual function according to the claims without great loss of cooling performance.

Alternatively, the coolant cooler comprises a first cooling section, which is assigned to the first sub-area, and a second cooling section, which is assigned to the second sub-area, the two cooling sections in the coolant cooler not being fluidically connected and the first cooling section being shorter than the second cooling section. This embodiment is particularly advantageous if it is a heat exchanger with two or more cooling sections or if the coolant cooler comprises meandering channels. However, the first and second cooling sections can also be of the same length, which is particularly advantageous if the coolant cooler is a downward or cross-flow cooler.

According to a further development, the first sub-area of the coolant cooler adjoins the second sub-area of the coolant cooler or is arranged adjacently. The first and second sub-areas can be in direct mechanical contact with one another, i.e. they can abut one another and thus be regarded as one component, as it were. For example, the two areas can only be separated from one another via a partition. The advantage of this is that space-saving precooling of the filling line can be achieved. In addition, due to the adjacent arrangement of the sub-areas, the cooling fan, which is usually installed on the coolant cooler, can also ensure a circulation of the ambient air and thus efficient cooling on the filling line.

According to one embodiment, coolant from the expansion tank is supplied to the inlet of the first sub-region of the coolant cooler via the filling line of the associated cooling circuit. In other words, coolant from the expansion tank first runs through the filling line and then enters the air-cooled heat exchanger, which is designed as a first sub-area of a coolant cooler, via the inlet. By passing through the heat exchanger or the first sub-area of the coolant cooler, the coolant is cooled, which then enters the cooling circuit after exiting the heat exchanger, whereby it can pass a further section in the filling line beforehand.

Furthermore, it is preferably provided that the outlet of the first sub-area of the coolant cooler is upstream of the inlet of the second sub-area of the coolant cooler. That is, in normal operation, coolant flows from the outlet of the first sub-region of the coolant cooler to the Inlet of the second sub-region of the coolant cooler, the coolant being able to flow through or along further components, for example a coolant pump or the components to be cooled, in the meantime.

In order to ensure a reliable and stable hose connection between the filling line and the heat exchanger, a preferred embodiment provides that the inlet and / or outlet of the heat exchanger is designed as a hose connector or as a hose coupling. The opening for supplying the coolant into the heat exchanger is understood as the inlet, and the opening for the coolant to escape from the heat exchanger as the outlet. The heat exchanger can also comprise more than one inlet and more than one outlet. Furthermore, the inlet and / or outlet of the heat exchanger can also comprise a pipe coupling and / or flange connection.

According to a further embodiment (not according to the invention), the air-cooled heat exchanger is designed as a separate component which is only provided for cooling the coolant in the filling line. This means that the heat exchanger is explicitly not designed as a sub-area of a coolant cooler. The heat exchanger can be designed as an air-cooled tube bundle cooler, tube cooler or heat exchanger. Furthermore, the heat exchanger can comprise cooling fins and / or heat sinks. This embodiment is further characterized in that a coolant cooler of the associated cooling circuit is arranged downstream of the filling line. In other words, the coolant in the filling line passes through an air-cooled heat exchanger at one point on its way from the expansion tank to the entry into the cooling circuit and then a coolant cooler in the cooling circuit, which is not identical to the aforementioned air-cooled heat exchanger. The advantage of this variant is that, due to the spatial separation of the heat exchanger and coolant cooler, no heat transfer can occur between the two components. In contrast to the embodiment of the heat exchanger and coolant cooler as an assembly in direct contact, an undesired heat flow of the coolant, which is initially warm when entering the heat exchanger, is effectively prevented via the heat exchanger and coolant cooler wall to the cold cooling circuit.

According to one embodiment of the invention, exactly two cooling circuits operating at different temperature levels are each connected to a common expansion tank for coolant via at least one vent line and at least one filling line.

The air-cooled heat exchanger is provided on the filling line of the cooling circuit with a lower temperature level in order to precool the coolant from the common expansion tank before it enters the cooling circuit with a lower temperature level. In this way, warm coolant is advantageously prevented from being introduced into the cooling circuit at a lower temperature level.

The invention also relates to a motor vehicle, preferably a commercial vehicle, with a cooling device as described in this document. The cooling device can be used for fuel, oil, charge air, engine and / or battery cooling. Furthermore, the motor vehicle can comprise an internal combustion engine and / or electric motor and / or a fuel cell.

The invention also relates to a stationary system with a cooling device as described in this document. The stationary system can also include an internal combustion engine and / or electric motor and / or a fuel cell.

Figur 1

eine schematische Darstellung einer Kühlvorrichtung mit zwei Kühlkreisläufen, die mit einem gemeinsamen Ausgleichsbehälter verbunden sind, nach einem bevorzugten Ausführungsbeispiel der Erfindung, wobei einer der Kühlkreisläufe einen luftgekühlten Wärmeübertrager zur Vorkühlung der Füllleitung nach einer Ausführungsform der Erfindung umfasst;

Figur 2

eine Ausführungsform des luftgekühlten Wärmeübertragers zur Vorkühlung der Füllleitung als einen ersten Teilbereich eines Kühlmittelkühlers, gemäß eines Ausführungsbeispiels der Erfindung; und

Figur 3

eine Ausführungsform des luftgekühlten Wärmeübertragers als ein separates Bauteil zur Vorkühlung der Fülllleitung (nicht erfindungsgemäss).

The preferred embodiments and features of the invention described above can be combined with one another as desired. Further details and advantages of the invention are described below with reference to the accompanying drawing. Show it:

Figure 1

a schematic representation of a cooling device with two cooling circuits, which are connected to a common expansion tank, according to a preferred embodiment of the invention, wherein one of the cooling circuits comprises an air-cooled heat exchanger for pre-cooling the filling line according to an embodiment of the invention;

Figure 2

an embodiment of the air-cooled heat exchanger for pre-cooling the filling line as a first sub-region of a coolant cooler, according to an embodiment of the invention; and

Figure 3

an embodiment of the air-cooled heat exchanger as a separate component for pre-cooling the filling line (not according to the invention).

In Figure 1 an exemplary embodiment of the claimed cooling device 100 is shown schematically. This comprises two cooling circuits 10a, 10b, each of which has a ventilation line 1a, 1b and a filling line 2a, 2b with a, designed as a chamber, common expansion tank 3 for coolant are connected. In addition, however, the two cooling circuits 10a and 10b have no further fluidic connection to one another. The individual cooling circuits 10a and 10b, shown here greatly reduced for the sake of clarity, each include a coolant cooler 5a, 5b, a coolant pump 8a, 8b and a heat exchanger 9a, 9b, these components being connected via corresponding pipes 11a, 11b. During operation, the coolant pumps 8a, 8b pump coolant to the heat exchangers 9a, 9b, which are in contact with self-heating or externally heated components, for example an internal combustion engine. The pipes 11a, 11b lead in a manner known per se past the components to be cooled, for example engine components, or are led through them (not shown). In the heat exchangers 9a, 9b, heat is transferred from these components to the coolant, which is then pumped on to the respective coolant coolers 5a, 5b, for example a downdraft cooler. In the coolant coolers 5a, 5b, the heat stored in the coolant is finally given off to the ambient air. The coolant then flows again to the respective coolant pumps 8a, 8b and the cycle begins again.

If the coolant in the cooling circuits 10a, 10b is heated and thus expands during operation, this excess coolant is fed to the common expansion tank 3 by means of the ventilation lines 1a, 1b. Mixing of the coolants from the two cooling circuits 10a and 10b then takes place in the expansion tank 3. In the present case, the cooling circuit 10a has a lower operating temperature T ₁ than the cooling circuit 10b, as a result of which the coolant present in the expansion tank 3 will also have a mixed temperature between the operating temperatures of the two cooling circuits 10a and 10b. Because of this mixing of coolant in the expansion tank 3, coolant that is “too warm” would consequently be returned to the cooling circuit 10a with a lower temperature level via the filling line 2a. In order to prevent this, an air-cooled heat exchanger 4 is provided in the area of the filling line 2a of the cooling circuit 10a with a lower temperature level. This is designed as a first partial area 51 of a coolant cooler 5a, which is separated from a second partial area 52 of the coolant cooler 5a. Both the first and the second sub-area 51, 52 have their own inlet 61, 62 and outlet 71, 72 for coolant. In a manner that saves space, a pre-cooling of the coolant which is conducted via the filling line 2a into the cooling circuit 10a and which is "too warm" due to the previous mixing in the expansion tank 3 is achieved.

Figure 2 shows an embodiment of the air-cooled heat exchanger 4 for pre-cooling the filling line 2a as a first partial area 51 of a coolant cooler 5a. The coolant cooler 5a known per se in the prior art, for example in the form of a downdraft cooler, is subdivided via a vertical partition 12 into two subregions 51 and 52 that are separated from one another, that is, are not fluidically connected within the coolant cooler 5a. Coolant flows through each of the two sub-areas 51 and 52, which enters the respective sub-area 51, 52 via the corresponding inlet 61, 62 and leaves the respective sub-area 51, 52 via the corresponding outlet 71, 72 without mixing in between of coolant of the two circuits can take place.

In Figure 3 an embodiment (not according to the invention) is shown in which the air-cooled heat exchanger 4 is designed as a separate component 40 for pre-cooling the filling line 2a. It is therefore explicitly not part or sub-area 51 of a coolant cooler 5a. In the cooling circuit 10a itself, however, there is a coolant cooler 5a, which, however, only serves to cool the coolant in the cooling circuit 10a, while the air-cooled heat exchanger 4 pre-cools the coolant in the filling line 2a before it enters the cooling circuit 10a.

List of reference symbols

1a, 1b

Vent line

2a, 2b

Filling line

3

surge tank

4th

Air-cooled heat exchanger

5a, 5b

Coolant cooler

8a, 8b

Coolant pump

9a, 9b

Heat exchanger

10a, 10b

Cooling circuit

11a, 11b

Pipeline

12th

partition wall

40

Separate air-cooled heat exchanger

51, 52

First / second sub-area

61, 62

inlet

71, 72

Outlet

100

Cooling device

T1, T2

Cooling circuit operating temperature

Claims (8)

1. A cooling device (100) with at least two cooling circuits (10a, 10b), which are respectively connected via a venting line (1a, 1b) and a filling line (2a, 2b) to a common equalizing vessel (3) for coolant, characterized in that at least one of the filling lines (2a) is provided with an air-cooled heat exchanger (4), by means of which coolant is precooled before it enters the cooling circuit (10a) assigned to this filling line (2a), wherein the air-cooled heat exchanger (4) is designed as a first subregion (52) of a coolant cooler (5a), which is separated from a second subregion (52) of the coolant cooler (5a), wherein both the first and the second subregion (51, 52) have their own inlet (61, 62) and outlet (71, 72) for coolant.
2. The device according to Claim 1, characterized in that the coolant cooler (5a)

   a) comprises a plurality of tubes, preferably flat tubes, of which a first subset is assigned to the first subregion (51) and a second subset is assigned to the second subregion (52), wherein the two subsets of tubes in the coolant cooler (5a) are not fluidly connected and the first subset is smaller than the second subset, and/or

   b) comprises a first cooling section, which is assigned to the first subregion (51), and a second cooling section, which is assigned to the second subregion (52), wherein the two cooling sections in the coolant cooler (5a) are not fluidly connected and the first cooling section is shorter than the second cooling section.
3. The device according to one of the preceding claims, characterized in that the first subregion (51) of the coolant cooler (5a) is arranged adjacent to or alongside the second subregion (52) of the coolant cooler (5a).
4. The device according to one of the preceding claims, characterized in that coolant from the equalizing vessel (3) is supplied to the inlet (61) of the first subregion (51) of the coolant cooler (5a) via the filling line (2a) of the assigned cooling circuit (10a).
5. The device according to one of the preceding claims, characterized in that the outlet (71) of the first subregion (51) of the coolant cooler (5a) lies upstream of the inlet (62) of the second subregion (52) of the coolant cooler (5a).
6. The device according to one of the preceding claims, characterized in that the inlet and/or outlet (61, 71) of the air-cooled heat exchanger (4) is configured as a hose connector or as a hose coupling.
7. The device according to one of the preceding claims, characterized in that precisely two cooling circuits (10a, 10b), operating at different temperature levels, are respectively connected via at least one venting line (1a, 1b) and at least one filling line (2a, 2b) to a common equalizing vessel (3) for coolant, wherein the air-cooled heat exchanger (4) is provided on the filling line (2a) of the cooling circuit (10a) with a lower temperature level in order to precool coolant from the common equalizing vessel (3) before it enters the cooling circuit (10a) with the lower temperature level.
8. A motor vehicle, preferably a commercial vehicle, and/or a stationary installation with a cooling device (100) according to one of Claims 1 to 7.

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