EP1588034A2

EP1588034A2 - Cooling circuit of an internal combustion engine comprising a low-temperature radiator

Info

Publication number: EP1588034A2
Application number: EP04701951A
Authority: EP
Inventors: Klaus Hassdenteufel; Stefan Rogg
Original assignee: Behr GmbH and Co KG
Current assignee: Mahle Behr GmbH and Co KG
Priority date: 2003-01-16
Filing date: 2004-01-14
Publication date: 2005-10-26
Anticipated expiration: 2024-01-14
Also published as: DE10301564A1; JP4644182B2; US20060254538A1; EP2573354A1; US7406929B2; EP1588034B1; WO2004063543A2; JP2006515658A; WO2004063543A3

Abstract

The invention relates to a cooling circuit of an internal combustion engine of motor vehicles, comprising a main cooling circuit that encompasses a section located upstream of the radiator, a main radiator, a radiator return path, a coolant pump, a main thermostat, and a bypass or short circuit which is disposed between the main thermostat and the coolant pump. Said cooling circuit further comprises a low-temperature circuit encompassing a low-temperature radiator, a low-temperature radiator return path, a valve unit, and an additional heat exchanger.

Description

, BEHR GmbH & Co. KG Mauserstrasse 3, 70469 Stuttgart

Cooling circuit of an internal combustion engine with a low-temperature cooler

The invention relates to a cooling circuit of an internal combustion engine of motor vehicles according to the preamble of claim 1 and a coolant cooler of a cooling circuit of an internal combustion engine according to the preamble of claim 11 - both known from DE-A 196 37 817.

From DE-A 196 37 817 and the corresponding EP-B 861 368, a cooling circuit of an internal combustion engine with a low-temperature cooler is known, which is connected in series with a main cooler on the coolant side. Through the main condenser flows a main flow of coolant, of which ^'in an ^outlet' side collecting tank branched off a partial flow and is conveyed in the opposite direction to the main flow through the Niedertem- peraturkühler. The branching of the partial flow is brought about by a partition arranged in an inlet box of the coolant cooler. The entry box thus has two chambers, namely one

Main chamber for the main coolant flow and a secondary chamber for the

^• escaping partial flow, which flows through the entire cooler twice and is therefore cooled more. The partial flow emerging from the secondary chamber is used for cooling gear oil and, if necessary, mixed with coolant from an expansion tank. The two partial flows are mixed by a valve unit, from which the conditioned coolant is fed to the transmission oil cooler for cooling or preheating. The cooling circuit also contains a main or engine Mostaten, which is arranged in the cooler return, ie on the coolant side behind the main cooler. The known cooling circuit or the known coolant cooler have various disadvantages; First of all, the series connection in a cooler block results in a reduced thermodynamic effectiveness of the entire cooler. The average temperature difference between coolant and cooling air is lower in the low-temperature cooler than in the main cooler, and thus the average temperature difference between coolant and cooling air is smaller for the entire assembly. In addition, this assembly results in thermal tension because the average coolant temperature in the main cooler is higher than that in the low-temperature cooler. These thermal stresses due to different expansion of the coolant tubes affect the tube plate connections, which can lead to leaks. Finally, the hydraulic voting in the entire cooling circuit is associated with difficulties in so far is dependent than the partial coolant flow through the low-temperature cooler of ^'the pressure loss of the return flow of the main stream and the partial stream. In order to achieve a sufficient amount of coolant through the coolant cooler and thus also through the downstream transmission oil cooler, a certain pressure drop in the return flow of the main flow is required, which is done here by the arrangement of the main thermostat in the cooler return flow. The restriction to circuits with a main thermostat on the cooler outlet side is disadvantageous in that there is no general applicability.

Another design of a coolant cooler in connection with an additional heat exchanger, in particular a transmission oil cooler, has become known from DE-A 199 26 052. The transmission oil cooler is fastened to the outlet-side header of the cooler and is flowed through by a partial flow of the coolant, which is caused by a partition or throttle element arranged in the outlet-side header between the coolant connections for the transmission oil cooler. A pressure drop resulting from this presses the partial coolant flow through the transmission oil cooler. A disadvantage of this arrangement is that the transmission oil cooler is cut off from the coolant flow during engine warm-up, ie when the main thermostat is closed, so that neither the transmission oil is heated when Engine warm-up cooling is still possible in winter. In addition, no control of the amount of coolant is possible.

A further simplified form of transmission oil cooling is known from the arrangement of a transmission oil cooler in the outlet water tank of a coolant cooler. B. from DE-A 197 11 259. Again, no control of the coolant amount is possible, and during the warm-up phase of the engine, the transmission oil cooler is cut off from the coolant flow.

It is an object of the present invention to improve the heating and / or cooling of an additional fluid with the cooling circuit or coolant cooler mentioned at the outset by ensuring adequate cooling even in thermally critical operating states and an adequate supply of coolant even in engine warm-up, and the cooling medium cooler has a higher thermodynamic effectiveness and allows hydraulic integration with low pressure drops.

This object is achieved from the features of claims 1 and 11. Advantageous embodiments of the invention result from the respective subclaims.

The parallel connection of the main coolant flow and partial flow in the low-temperature range results in a strong reduction in the coolant temperature without pre-cooling, ie due to a lower coolant flow rate. The invention is applicable to cooling circuits in which the main thermostat is arranged either in the cooler flow or in the cooler return. Advantageously, the partial flow is separated from the main flow by a partition wall arranged in the outlet-side collecting box or a “leaky partition wall”, ie a partition wall which is provided with a throttle point The output of the low-temperature cooler is advantageously connected to the main thermostat, the bypass or the cooler flow, so that the transmission oil cooler is also connected to the engine in the warm-up phase, ie when the main thermostat is closed to supply sufficient amount of coolant. Advantageously, a mixing thermostat is used in the return of the low-temperature cooler, which regulates the mixing temperature from the return of the low-temperature cooler and from the inlet on the engine side for the transmission oil cooler inlet The supply of cold coolant is prevented. This can prevent excessive transmission oil cooling and excessive transmission oil heating during engine warm-up. This lowers fuel consumption and emissions, improves heating comfort and the life of the gear oil.

In the coolant cooler according to the invention, the main area and the low-temperature area consist of a common tube / fin block which is flowed through in parallel, i. H. there is no pre-cooling of the partial flow. This means a higher thermodynamic effectiveness for the entire cooler, since the mean temperature difference between coolant and cooling air increases. On the other hand, the mean temperature difference in the pipes of the main area and those of the low-temperature area is smaller, so that there are no harmful voltages for the radiator block. This also applies if the low-temperature section is flowed through a second time in the opposite direction by a so-called redirection in depth. This allows the outlet temperature of the partial flow to be reduced even further.

Exemplary embodiments of the invention are shown in the drawings and are described in more detail below. Show it

1 shows a first cooling circuit with a main thermostat on the cooler inlet side,

2 shows a second circuit with a main thermostat on the cooler outlet side, FIG. 3 shows a third, simplified circuit with a main thermostat on the cooler inlet side, FIG. 4 shows a fourth, simplified circuit with a cooler outlet side Main thermostat, Fig. 5 shows a coolant cooler with an integrated transmission oil cooler and Fig. 6 shows a coolant cooler with an outlet-side header box on which a transmission oil cooler is attached.

Fig. 1 shows a cooling circuit of an internal combustion engine 1 of a motor vehicle, not shown. Heated coolant enters a main thermostat 2 from a motor return 1 a, to which a cooler flow 3 and a short circuit or bypass 4 are connected. The flow 3 opens into a cooler 5 with an inlet box 6 and an outlet-side header box 7. The cooler 5 has a main region 5a and a low-temperature region 5b, through which a coolant main flow and a coolant secondary or partial flow flow in parallel to one another , For this purpose, the outlet-side header box 7 has two chambers 7a, 7b, which are separated from one another by a partition 7c. In contrast, the inlet-side header box 6 is continuous, i. H. without partition. The main coolant flow enters the cooler return 8 from the main chamber 7a, merges with the bypass 4 at the union point 9 and is fed back into the internal combustion engine 1 via a coolant pump 10 via the engine flow 1b. A low-temperature cooler return 11 adjoins the low-temperature region 5b or the outlet-side secondary chamber 7b, which is fed into the cooler return 8 at the union point 12. In the low-temperature cooler return 11, a transmission oil cooler 13 is switched on. Between the secondary chamber 7b and the transmission oil cooler 13, a mixing thermostat 14 is connected to the return 11, which is connected to the main thermostat 2 via a branch line 15, into which an opening or warm-up thermostat 16 is connected.

The function of the cooling circuit is as follows: with a warm internal combustion engine. 1, the main thermostat to the cooler flow 3 is fully open and closed to the bypass line 4, ie the coolant flows into the cooler 5, where it flows through both areas, the main area 5a and the low-temperature area 5b, in parallel. The main stream returns to the internal combustion engine 1 via the cooler return 8 and the coolant pump 10. The partial flow cooled in the low-temperature region 5b passes via the return 11 into the mixing thermostat 9, where warm coolant from the engine outlet 1 a is mixed in via the branch line 15, if necessary, in order to regulate the transmission oil cooling.

In the case of a cold internal combustion engine, ie at the beginning of the warm-up phase, the main thermostat 2 is closed towards the radiator flow 3 and fully opened to the bypass line 4. No coolant flows through the radiator 5, but rather through the bypass line 4 to the engine inlet 1b. The mixing thermostat 14 and the downstream transmission oil cooler 13 thus do not receive any cold coolant. Rather, the mixing thermostat 14 receives only warm coolant from the engine outlet 1a. Since the coolant at the engine outlet 1 a has not yet reached the operating temperature in this operating state, the possibility of cooling the transmission oil is sufficient. At the start of engine warm-up, the situation arises that the gear oil is colder than the coolant. The gear oil will then _. heated in the transmission oil cooler 13 by the coolant flow. The heating of the gear oil makes sense within certain limits, as it quickly reaches the operating temperature and reduces friction losses in the gear. However, it is advantageous to start heating the transmission oil only after a certain period of time after the engine warm-up has started in order to limit the heat loss of the engine cooling circuit. The inflow of warm coolant from the engine outlet 1a to the mixing thermostat 14 and to the downstream transmission oil cooler 13 can be prevented by the warm-up thermostat 16. This only opens when the coolant at the engine outlet 1 a has reached a certain temperature.

If the main thermostat works in the control range, it is partially open towards the radiator flow 3 and the bypass line 4. The mixing thermostat 14 is then supplied with cold coolant from the low-temperature range 5b and with warm coolant from the engine outlet 1a, from which the coolant temperature suitable for the transmission oil temperature is mixed together.

FIG. 2 shows a variant of the first cooling circuit according to FIG. 1, the same reference numbers being used for the same parts. In contrast to 1, the main thermostat 2 is arranged here in the return 8 of the coolant cooler 5. In warm internal combustion engine 1 and the fully opened main thermostat 2, the coolant flow through the radiator 3 flows to the radiator 5, through which it flows in parallel ^'in a main flow and a partial flow. The partial flow occurs through the side chamber 7b into the return line 11, in which ^'the mixing thermostat 14 and the transmission oil cooler 13 are connected. The return 11 is fed to the bypass performance 4 or the flow of the coolant purge 10 at the union point 17. In the mixing thermostat 14, warm coolant from the engine outlet 1 a or from the radiator inlet 3 is mixed in, if necessary, via a branch line

18, in which the opening or warm-up thermostat 16 is connected.

^■ If the main thermostat 2 is closed to the radiator return 8 and is opened to the engine outlet 1 a, no coolant flows through the main part 5 a of the radiator 5. Instead, the main coolant flow is led directly to the coolant pump 10 via the short circuit 4. This condition occurs during engine warm-up or at least temporarily in winter operation. Depending on the position of the mixing thermostat .14, a partial coolant flow can also ^• pass through the low-temperature part 5b in this case. The mixed thermostat 14 then has cold coolant from the low-temperature part 5b and warm coolant from the engine outlet 1a or from the radiator inlet via the branch line 18, so that the temperature of the coolant flowing to the transmission oil cooler 13 can be regulated by the mixed thermostat 14.

At the beginning of the engine warm up, the situation arises that the transmission oil is colder than the coolant. The transmission oil is then heated in the transmission oil cooler 13 by the coolant flow. In order to allow the heating of the gear oil only after a certain period of time after the engine has warmed up, the inflow of the warm coolant from the engine outlet 1a or from the radiator inlet 3 to the mixing thermostat 14 can be prevented by the warm-up thermostat 16. The warm-up thermostat 16 only opens when the coolant at the engine outlet 1a or in the radiator inlet 3 has reached a certain temperature. The flow through the low-temperature part 5b would also result in heat loss for the coolant circuit represent. ^■ It is thereby prevented in this case that the mixing thermostat 14 is closed to the low-temperature part 5b, because the coolant temperature at the outlet of the low-temperature part 5b is significantly below the target temperature for exit of the mixing thermostat fourteenth ^■

If the main thermostat 2 operates in the control range, it is partially open to the radiator return 8 and to the engine outlet 1a. The mixing thermostat 14 is also supplied in this case with cold coolant from the low temperature part 5b and with warm coolant from the engine outlet 1 a or from the radiator inlet 3, whereupon the coolant temperature suitable for the transmission oil temperature is mixed together.

With regard to the cooling circuits according to FIGS. 1 and 2, it is found that the mixing thermostat 14 can be an expansion thermostat, a map thermostat or a control valve unit actuated by external energy. The control variable for the mixed thermostat 14 can be the temperature of the hot coolant from the engine outlet 1 a or from the radiator inlet 3, the coolant temperature at the outlet of the mixed thermostat 14 or the coolant temperature at the outlet of the transmission oil cooler 13. The warm-up thermostat 16 can optionally also be arranged between the mixing thermostat 14 and the transmission oil cooler 13 or - in the case of the main thermostat 2 arranged on the cooler inlet side - between the engine outlet 1 a and the radiator inlet 3. In the latter case, the warm coolant is supplied to the mixed thermostat 14 from the radiator inlet 3.

The cooling circuits with transmission oil cooler 13 _v according to FIGS. 1 and 2 can be simplified and thereby optimized in terms of cost, in that the mixing thermostats 14 are dispensed with and only one warm-up thermostat 16 is used in each case. Such cycles are described below.

Fig. 3 shows a simplified cooling circuit, in which the same reference numerals are used for the same parts. The main thermostat

2 is arranged in the radiator inlet 3. The transmission oil cooler 13 is arranged in the return 11 of the low-temperature region 5b. Via a branch line device 19 from the bypass 4 is fed through the warm-up thermostat 16 coolant into the return 11.

If the main thermostat 2 to the radiator inlet 3 is fully open and closed to the bypass line 4, the coolant flows into the coolant cooler 5. From the outlet of the low-temperature region 5b, the cooled coolant partial flow reaches the transmission oil cooler 13. Then the return 11 at the union point 12 in the cooler return 8 fed.

If the main thermostat 2 is closed towards the radiator inlet 3 and fully opened to the bypass line 4, no coolant flows through the cooler 5. Instead, the main coolant flow is led directly to the coolant pump 10 via the bypass line 4. This condition occurs during engine warm-up or at least temporarily during winter operation. In this case, no cold coolant is supplied to the transmission oil cooler 13. Via the branch 19 from the bypass line 4, warm coolant passes from the engine outlet 1 a to the warm-up thermostat 16 and from there to the inlet of the transmission oil cooler 13. Since the coolant at the engine outlet 1 a has not yet reached the operating temperature in this state, the possibility of cooling the Sufficiently given gear oil. At the beginning of engine warm-up, the situation arises that the transmission oil is colder than the coolant. The transmission oil is then heated in the transmission oil cooler 13 by the coolant flow. It is advantageous to allow the transmission oil to be heated only after a certain period of time after the engine has warmed up. This is achieved in that the warm-up thermostat 16 only opens when the coolant at the engine outlet 1 a or in the bypass line 4 has reached a certain temperature.

If the main thermostat 2 works in the control range, it is partially open towards the cooler flow 3 and the bypass line 4. The transmission oil cooler 13 is then supplied with a mixture of cold coolant from the low temperature range 5b and warm coolant from the engine outlet 1 a.

FIG. 4 shows a simplified cooling circuit, in which the same reference numbers are used for the same parts. The main thermostat is 2 arranged here in the cooler run 8. The warm-up thermostat 16 and the transmission oil cooler 13 are arranged in the return 11 of the low-temperature region 5b or the low-temperature cooler 5b. After its exit from the transmission oil cooler 13, the return 11 is brought together with the short-circuit line 4 at the union point 20 and is fed from there to the coolant pump 10.

If the main thermostat 2 is closed towards the radiator return 8 and fully opened towards the engine outlet 1a, no coolant flows through the main region 5a of the radiator 5. Instead, the main coolant flow is led directly to the coolant pump 0 via the short circuit 4. This condition occurs during warm-up or at least partially during winter operation. Depending on the position of the opening or warm-up thermostat 10, a partial coolant flow can also pass through the low-temperature cooler 5b in this case. Cold coolant flows into the transmission oil cooler 13 from the opening thermostat 16. The opening thermostat 16 ensures that the coolant has a minimum temperature, so that an excessive cooling of the transmission oil is prevented. At the beginning of engine warm-up, the situation arises that the transmission oil is colder than the coolant. The gear oil is then heated in the gear oil cooler 13 by the coolant flow. It is advantageous to allow the transmission oil to be heated only after a certain period of time after the engine has warmed up. This is achieved in that the warm-up thermostat 16 only opens when the coolant at the outlet of the low-temperature cooler 5b has reached a certain temperature.

If the main thermostat 2 operates in the control range, it is partially open towards the radiator return 8 and the engine outlet 1 a. The transmission oil cooler 13 is also supplied in ^this' case of the low temperature part 5b with cold coolant, which, however, has a minimum temperature due to the warming-up thermostat sixteenth

In addition to the cooling circuits described above in accordance with FIGS. 1 to 4, it is found that these are shown in simplified form insofar as, for example, an expansion tank and a heating circuit are not shown. represents are. Warm coolant can also be supplied to the mixing thermostat or the transmission oil cooler from the expansion tank. Incidentally, in the aforementioned cooling circuits, a transmission oil cooler was selected only as an example as an additional heat exchanger. The latter can also be replaced by another consumer, ie another heat exchanger or an electronic component to be cooled. The opening thermostat 16 can - like the mixing thermostat 9 - be an expansion thermostat, a map thermostat or a valve unit actuated by external energy. This also applies to the main thermostat 2.

Finally, the warm-up thermostat 16 can also be arranged between the transmission oil cooler 13 and the union 12, 17, 20. The opening time of the warm-up thermostat 16 then also depends essentially on the transmission oil temperature. At low temperatures of the transmission oil and the coolant, the warm-up thermostat 16 is closed and the transmission oil is neither heated nor cooled. When the coolant temperature is high and the transmission oil temperature is low, the warm-up thermostat 16 is opened and the transmission oil is heated. At low or high temperature of the coolant and high temperature of the transmission oil, the warm-up thermostat 16 is opened and the transmission oil is cooled.

FIG. 5 shows a coolant cooler 50, which corresponds to the coolant cooler 5 shown in FIG. 1, the gear oil cooler 13 shown there and the mixing thermostat 14 being combined with the coolant cooler to form a structural unit 50. The coolant cooler 50 has a uniform tube / fin block, consisting of a main area 50a and a secondary or partial area 50b. The pipes (not shown) of this pipe / finned view 50a, 50b lead on the one hand into a coolant inlet box 51 with a coolant inlet 52 and. into an outlet-side header box 52 with a coolant outlet 53. The header box 52 is divided by a partition 54 into a main chamber 55, which opens into the outlet 53, and a secondary chamber 56. The dividing wall 54 is sealed in the exemplary embodiment shown, but it can also have a throttle point or a valve (not shown ⁾ , so that both chambers 55, 56 can communicate with one another Longitudinal partition wall 57 divided, so that there is a mixing chamber 58, which communicates with the main chamber 55 in the region of the outlet opening 53. A gear oil cooler 59 with two gear oil connections 59 a, 59 b leading to the outside is arranged in the mixing chamber 58. In the area of the secondary chamber 56, a mixing thermostat 60 is integrated in the mixing chamber 58, which is in fluid communication with an inlet 60a with the secondary chamber 56 and with an outlet 60b with the mixing chamber 58. A second input 60c of the mixing thermostat 60 can be connected to the coolant circuit described above. The thermostatic cartridge 60 is sealed with seals against the receptacle in the header box. In one embodiment, the longitudinal partition 57 can be an integral part of the collecting box 52 or an additional component. In order to simplify the production of the collecting tank 52, it is advantageous to attach the longitudinal partition 57 to the transmission oil cooler 59. The longitudinal partition 57 is then to be designed in such a way that it seals when the transmission oil cooler 59 is installed in the collecting box 52. Corresponding sealing surfaces are to be provided in the collecting box 52 and on the longitudinal partition 57. A seal or the design of the partition as a hard / soft part with a molded sealing lip may also have to be provided.

As a result of the partition wall 54 arranged in the outlet-side collecting box 52, the main area 50a and the low-temperature area 50b of the cooler 50 are flowed through in parallel, i. H. a main coolant flow is formed which exits into the main chamber 55 and leaves the cooler 50 via the outlet 53, and a partial flow which exits into the secondary chamber 56 and enters the mixing chamber 58 via the outlet 60b of the mixing thermostat 60. If necessary, coolant is admixed to this partial coolant stream via the further inlet 60 c. The coolant that has entered the mixing chamber 58 flows through the transmission oil cooler 59 and is then mixed into the main flow in the region of the outlet opening 53.

The main flow and the partial flow are dimensioned in such a way that the coolant partial flow through the low-temperature part 50b accounts for approximately 4% to 15% of the total coolant flow that enters the cooler 50 through the coolant inlet 52. The size of the low temperature part 50b is advantageously dimensioned such that the end face of the low-temperature part 50b makes up between 10% and 40% of the end face of the cooler 50. In between, in the range of 20% to 30% area, there is a preferred range. The coolant cooler 50 is preferably installed in the motor vehicle as a cross-flow cooler, that is to say with horizontally running pipes (not shown). The low temperature part 50b can be above or below, which depends on the cooling air flow in the vehicle. For example, in the lower area of the coolant cooler, further heat exchangers, e.g. B. intercooler, which heat the cooling air. An arrangement in the upper region would then be advantageous for better cooling of the low-temperature region 50b. As already mentioned, due to the relatively small temperature differences, the main area 50a and the low temperature area 50b can be produced in a tube / fin block with common tube sheets and header boxes. However, it can also be advantageous for the main chamber 55

And to design the secondary chamber 56 as separate chambers or to completely separate the two cooling areas 50a and 50b, i. H. into a separate main cooler and a separate low-temperature cooler, both of which are acted upon in parallel on the coolant side. The low-temperature part 50b can also be flowed through twice or more, for. B. by deflecting the coolant in depth, d. H. in the direction of the cooling air flow. This further reduces the coolant temperature. The low-temperature part can also be formed from a partial area of the cooler and additionally by a separate component. The two segments of the low-temperature part, which result in this design, can be flowed through in parallel or in succession by the partial coolant flow. The low-temperature part segment, which is a separate component, can be arranged in the cooling air flow in front of the cooler unit which contains the other low-temperature part segment. If the coolant partial flow flows through the two segments in succession, the thermodynamic effectiveness of the low-temperature part is similar to that

• with a redirection of the coolant at depth.

An advantage of designing the low-temperature part as a separate component or with a segment of the low-temperature part as a separate component is the reduced temperature change stress. The cooler main part can be simply flowed through or have a deflection.

FIG. 6 shows a further exemplary embodiment of a coolant cooler 61, which is constructed similarly to the coolant cooler 50 according to FIG. 5, namely with a main cooling area 61 a and a low temperature area 61 b, each with an inlet box 62 with a coolant inlet opening 63 and an outlet box 64 communicate with an outlet opening 65. A partition 66 is arranged in the outlet box 64 and divides it into a main chamber 67 and a secondary chamber 68. The main area 61 a and the partial area 61 b are thus flowed through in parallel by the coolant. The secondary chamber 68 is followed by a mixing chamber 69, into which a mixing thermostat 70 is inserted, which communicates both with the secondary chamber 68 and with the mixing chamber 69 on the output side and on the input side with the cooling circuit, not shown here. A mounting plate 71 is arranged on the outside of the outlet-side header box 64, by means of which a gear oil cooler 72 is attached to the coolant cooler 61 and is connected on the coolant side to the mixing chamber 69 and the main chamber 67, specifically via a coolant inlet channel 73 and a coolant outlet channel 74. The gear oil circuit, not shown is connected via the connecting pieces 72a, 72b, in contrast to the transmission oil cooler 59 according to FIG. 5, this transmission oil cooler 72 has its own housing for guiding the coolant. The housing is flange-shaped on its fastening side, clamped to the mounting plate 71 and sealed against the mounting plate 71 via a sealing plate 73. Conventional coolant inlet and outlet connections can thus be omitted. The mounting plate 71 is advantageously molded onto the header box 64 and contains the two coolant channels 73, 74. However, the recirculation of the partial coolant flow via the outlet channel 74 is only recommended for arranging the main thermostat in the cooler flow.

The gear oil cooler can be attached to the water tank, the fan frame or the module frame with or without a mounting plate. Other mounting locations on the cooling module or away from the cooling module are also possible. The transmission oil cooler can be designed with or without its own housing for guiding the coolant. In the version with a housing for guiding the coolant, there may be inlet and outlet connections for the coolant and gear oil. When used with a mounting plate, the coolant-side sockets can be dispensed with in whole or in part.

The mixing thermostat can be integrated into the mounting plate or attached directly to the transmission oil cooler. Further design options result from the arrangement of the mixing thermostat in the coolant guides, whereby the mixing thermostat can also be attached to the cooler, the fan frame, the module frame or at another location. The opening thermostat can be integrated in the mounting plate or attached directly to the transmission oil cooler. Further design options result from the arrangement of the opening thermostat in the coolant guides, the opening thermostat also being able to be attached to the cooler, the fan frame, the module frame or at another location. It is also possible to integrate the opening thermostat in the water tank. The design options correspond in this case to the integration of the mixing thermostat in the water tank.

Claims

P atent claims

1. Cooling circuit of an internal combustion engine of motor vehicles with a main cooling circuit, consisting of a radiator flow (3), a main cooler (5a), a radiator return (8), a coolant pump (10), a main thermostat (2) and a bypass or short circuit (4 ) between the main thermostat (2) and coolant pump (10), and with a low-temperature circuit consisting of a

Low-temperature cooler (5b), a low-temperature cooler return (11), a valve unit and an additional heat exchanger, characterized in that the low-temperature cooler (5b) is connected in parallel to the main cooler (5a).

Cooling circuit according to claim 1, characterized in that the main thermostat

(2) is arranged in the cooler flow (3).

3. Cooling circuit according to claim 1, characterized in that the main thermostat (2) is arranged in the radiator return (8).

4. Cooling circuit according to claim 1, 2 or 3, characterized in that the additional heat exchanger is designed as a transmission oil cooler (13). ^'

5. Cooling circuit according to claim 2, characterized in that the valve unit is designed as a mixing thermostat (14) with two inputs and one output, that the first input and the output are connected to the return line (11) of the low-temperature cooler (5b) and the second Input is connected to the main thermostat (2).

6. Cooling circuit according to claim 5, characterized in that a warm-up thermostat (16) is connected between the second input and the main thermostat (2).

7. Cooling circuit according to claim 2, characterized in that the valve unit is designed as a warm-up thermostat (16) which is connected between the return line (11) of the low-temperature cooler (5b) and the bypass (4).

8. Cooling circuit according to claim 3, characterized in that the valve unit is designed as a mixing thermostat (14) with two inputs and one output, that the first input and the output are connected to the return line (11) of the low-temperature cooler (5b) and the second input is connected to the cooler flow (3).

9. Cooling circuit according to claim 8, characterized in that a warm-up thermostat (16) is connected between the cooler flow (3) and the second input.

10. Cooling circuit according to claim 3, characterized in that the valve unit is designed as a warm-up thermostat (16) which is connected to the return line (11) of the low-temperature cooler (5b).

11. Coolant cooler of a cooling circuit of an internal combustion engine of a motor vehicle, consisting of a tube/fin block, a coolant inlet box (51, 62) with a coolant inlet (52, 63), a collecting box (52, 64), which are in coolant connection with the tube/fin block , wherein the tube/fin block is divided into a main area (50a, 61a) and a low temperature area (50b,

61 b), and with coolant outlets for a main coolant flow and a partial coolant flow, characterized in that the main area (50a, 61 a) and the low temperature area (50b, 61 b) are connected in parallel.

12. Coolant cooler according to claim 11, characterized in that a separating element (54, 66) is arranged in the collecting box (52, 64), which divides the tube/fin block into the main area (50a, 61a) and the low-temperature area (50b, 61 b ) and the collecting box (52, 64) are divided into a main chamber (55, 67) and a secondary chamber (56, 68).

13. Coolant cooler according to claim 12, characterized in that the separating element is designed as a tight partition (54, 66).

14. Coolant cooler according to claim 12, characterized in that the separating element is designed as a leaky partition with a throttle point.

15. Coolant cooler according to claim 12, characterized in that the separating element is designed as a partition with a valve.

16. Coolant cooler according to one of claims 11 to 15, characterized in that the low temperature region (50b, 61b) can be flowed through by a partial coolant flow which amounts to approximately 4% to 15% of the total coolant flow.

17. Coolant cooler according to one of claims 12 to 16, characterized in that an additional heat exchanger, in particular a transmission oil cooler (59, 72), is integrated into or with the collecting box (52, 64) and the coolant partial flow can flow through it.

18. Coolant cooler according to claim 12 and 17, characterized in that an open longitudinal partition (57) is arranged in the main chamber (55), which divides a mixing chamber (58) in which the additional heat exchanger (59) is arranged.

19. Coolant cooler according to claim 18, characterized in that a mixing thermostat (60) is integrated into the mixing chamber (58), which also the secondary chamber (56) and the mixing chamber (58) are in coolant connection and can be connected to the cooling circuit.

20. Coolant cooler according to claim 17, characterized in that the additional heat exchanger (72) is attached to the collecting box (64) by means of a mounting plate (71).

21. Coolant cooler according to claim 20, characterized in that in the area of the secondary chamber (68) a mixing chamber (69) is arranged, in which a mixing thermostat (70) is integrated, which is connected to the secondary chamber (68) and the mixing chamber (69). is in coolant connection and can be connected to the coolant circuit, and that the additional heat exchanger (72) is in coolant connection with the mixing chamber (69) and the main chamber (67).