SE1850640A1

SE1850640A1 - A cooling system for cooling of two objects to different temperatures

Info

Publication number: SE1850640A1
Application number: SE1850640A
Authority: SE
Inventors: Ola Hall; Zoltan Kardos
Original assignee: Scania Cv Ab
Priority date: 2018-05-28
Filing date: 2018-05-28
Publication date: 2019-11-29
Also published as: SE542873C2

Abstract

Cooling system for cooling of two objects to different temperatures. The cooling system comprises an first cooling circuit (A) which comprises a first coolant circulating member (9), a first radiator (17) and a first object (2) to be cooled, and a second circuit (B) which comprises a second coolant circulating member (6, 22), a second radiator (24) and a second object (6, 20) having capacity to have a higher temperature than the first object. The cooling system comprises a control valve (15, 31) which, in a first position, is configured to form separate flow paths for the coolant in first circuit (A) and in the second circuit (B), and in a second position configured to form a common flow path for the coolant through first circuit (A) and in the second circuit (B) such that the coolant flows in series through the first radiator (17) and the second radiator (24).

Description

A cooling system for cooling of two objects to different temperatures BACKGROUND OF THE INVENTION AND PRIOR ART The present invention relates to a cooling system for cooling of two objects to different temperatures according to the preamble of claim l.

Heavy vehicles may be equipped with a cooling system for cooling of objects withdifferent cooling demands to different temperatures. The cooling system can, forexample, be used to cool a combustion engine which may have an optimal operatingtemperature within a temperature range of 105- ll5°C and a hydraulic retarder whichmay have very large temporarily load on the cooling system when it is engaged. Such acooling system has to be dimensioned so that the coolant temperature does not risesabove ll5 °C even when the hydraulic retarder is engaged. The hydraulic retarder maybe of the kind which uses retarder oil as Working ﬂuid. In this case, the cooling systemis used to cool the oil in a retarder cooler. Altematively, the hydraulic retarder is a socalled water retarder which use coolant from the cooling system as cooling ﬂuid aswell as working ﬂuid. The cooling system for cooling of a combustion engine in avehicle may also be used to cool other components or mediums having differentcooling demands than the combustion engine. Such components or mediums may becharge air, recirculating exhaust gases, engine oil, gearbox oil, refrigerant in a condenser of an AC system etc.

Hybrid vehicles and pure electric vehicles may be powered by an electric power unitwhich may comprise an electric machine which altemately works as motor andgenerator, an electric energy storage for storing of electrical energy and powerelectronics for controlling the flow of electrical energy between the electrical energystore and the electric machine. The electrical energy storage may have an optimaloperating temperature within a temperature range of 20- 30°C while a maximumallowable temperature for the power electronics and the electric machine may be about60 °C. It is difficult to cool these components by a single cooling system with a high efficiency.

SUMMARY OF THE INVENTION The object of the present invention is to provide a cooling system able to cool two objects to different temperatures with a high efficiency.

This purpose is achieved with the features deﬁned in claim l. When a conventionalcooling system is used to cool two objects to different temperatures, the coolanttemperature is defined by the object to be cooled to the lowest temperature. Thepresent cooling system comprises a first coolant circuit provided with a first radiatorand a first object, and a second circuit provided with a second radiator and a secondobject which is capable to be heated to a higher temperature than the first object. Thecooling system comprises a control valve settable in a first position in which the firstcircuit and the second circuit form two separate ﬂow paths, and in a second position inwhich the first circuit and the second circuit form a common ﬂow path for the coolant in which the coolant ﬂows in series through the first radiator and the second radiator.

The cooling capacity of a cooling circuit is related to the temperature differencebetween the coolant and the cooling air stream in the radiator. A high coolanttemperature results in a larger coolant temperature drop in a radiator than a low coolanttemperature. During operating conditions when the control valve is in the first positionin which the first circuit and the second circuit are separated, it is possible to create ahigher coolant temperature in the second circuit than in the first circuit. This results ina larger coolant temperature drop in the second radiator and a more efficient cooling ofthe second object. During operating conditions when the cooling demand of the firstobject is high and the cooling demand of the second object is negligible, it is possibleto set the control valve in the second position. In this case, the coolant receives atemperature drop in the first radiator an in the second radiator. The coolant receives alower temperature before it enters the first object, which results in a more efficientcooling of the first object. During operating conditions when the coolant temperaturein the second circuit is high and the first object has a too low temperature, it is possible to set the control valve in the second position such that warrn coolant from the second Circuit is directed to the first circuit in order to heat the first object to a desiredoperating temperature. In this case, the cooling systern comprises two circuits eachcomprising a radiator and an object to be cooled. It is possible to provide coolingsystern comprising three a more such circuits which is temporarily separated and connected to each other by means of a control valve.

According to an embodiment of the invention, the control valve is, in the first position,configured to direct coolant from the first object towards the first radiator at the sametime as it direct coolant from the second radiator towards the second object. In thiscase, the control valve separates the coolant flow in the first circuit from the coolantﬂow in the second circuit. The control valve may, in the second position, be configuredto direct coolant from the first object towards the second object at the same time as itdirects coolant from the second radiator towards the first radiator. In this case, thecontrol valve directs the entire coolant ﬂow from the first circuit to the second circuitand the entire coolant ﬂow from the second circuit to the first circuit. The control unitmay have a first inlet receiving coolant from a first object outlet line and a second inletreceiving coolant from a second radiator outlet line. The control unit may have a firstoutlet directing coolant to a first radiator inlet line and a second outlet directing coolant to a second object inlet line.

According to an embodiment of the invention, the control valve comprises a valvebody movably arranged to the first position and the second position. Such a controlvalve may have a simple design. The valve body may, for example, be rotatablearranged to the first position and the second position. The control valve may besettable in at least one additional position in which it directs a part of the coolant ﬂowin the first circuit to the second circuit and a corresponding part of the coolant ﬂowfrom the second circuit to the first circuit. The control valve may include a therrnostat.In this case, the control valve directs the coolant ﬂow in the first circuit to the firstradiator or a first radiator bypass line in view of the coolant temperature in the first circuit.

According to an embodiment of the invention, the Cooling system comprises a controlunit configured to control the position of the control valve. In order to provide areliable and fast control of the control valve, it is advantageous to use an electriccontrol unit Which controls the control valve by means of inforrnation from relevant operating parameters.

According to an embodiment of the invention, the control unit is configured to controlthe positioning of the control valve by means of inforrnation about a parameter relatedto the temperature of the first object. The first object may for example have amaximum acceptable temperature Which ought not to be exceeded. In this case, thecontrol unit controls the control valve such that the temperature of the first object doesnot exceeds the maximum acceptable temperature. The control unit may altemativelyor in combination be configured to control the positioning of the control valve bymeans of inforrnation about a parameter related to the temperature of the coolantentering the first object. In order to provide a desired cooling of the first object, thecontrol unit may control the control valve such that the temperature of the coolant directed to the first object does not exceeds a predeterrnined temperature.

According to an embodiment of the invention, the control unit is configured to controlthe positioning of the control valve in order to create a maximum acceptabletemperature in the respective circuits. In this case, a maximum temperature differencebetween the coolant and the cooling air stream is achieved in the respective radiators such that the circuits receives a maximum coolant capacity.

According to an embodiment of the invention, the control unit is configured to controlthe positioning of the control valve by means of inforrnation about a parameter relatedto the temperature of the second object. The second object may for example have amaximum acceptable temperature Which ought not to be exceeded. In this case, thecontrol unit controls the control valve such that the temperature of the second objectdoes not exceeds the maximum acceptable temperature. The control unit mayaltematively or in combination be configured to control the positioning of the control valve by means of inforrnation about a parameter related to the temperature of the coolant entering the second object. In order to provide a desired cooling of the secondobject, the control unit may control the control Valve such that the temperature of the coolant directed to the second object does not exceeds a predeterrnined temperature.

According to an embodiment of the inVention, the second object is a component whichis temporarily engaged. The cooling system is particularly suitable to cool a secondobject which is temporarily engaged and which is able to withstand a highertemperature than the first object. The second object may be a hydraulic retarder suchas an oil retarder in which the coolant cools oil in a retarder cooler or a water retarder in which the coolant is used as cooling ﬂuid as well as working ﬂuid.According to an embodiment of the inVention, the first object is an engine. The firstobject may be a combustion engine such as a diesel engine or an Otto engine or another kind engine such as an electric engine.

The inVention is also related to a Vehicle comprising a cooling system according to the above.

BRIEF DESCRIPTION OF THE DRAWINGS In the following preferred embodiments of the invention is described, as examples, with reference to the attached drawing, in which: Fig. l shows a cooling system according to a first embodiment of the inventionduring a first operating condition, Fig. 2 shows the cooling system in Fig. l during a second operating conditionand Fig. 3 shows a cooling system according to a second embodiment of the inVention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THEINVENTION Figs. 1 and 2 show a schematically indicated vehicle 1 Which may be a heavy vehicle.The vehicle 1 is driven by a combustion engine 2. The combustion engine 2 may be anOtto engine or a diesel engine. Altematively, another kind of engine is used such anelectrical engine. The vehicle 1 comprises a powertrain Which in addition to thecombustion engine 2 comprises a clutch mechanism 3, a gearbox 4 and a gearboxoutput shaft 5. The vehicle 1 is equipped With an oil retarder 6 comprising a stator unitWhich is stationary arranged in the vehicle and a rotor unit Which is, via a motiontransmitting mechanism 7, connected to the gearbox outlet shaft 5. Thus, the rotor unitis rotated by a speed defined by the speed of the gearbox outlet shaft 5 and the gearratio in the motion transmitting mechanism 7. The stator unit and the rotor unit definea toroidal space receiving oil during activation of the retarder. The stator unitcomprises stator vanes and the rotor unit comprises rotor vanes situated in the toroidalspace. A control unit 8 is adapted to control the activation of the oil retarder 6 bymeans of a retarder valve 6a in vieW of information from a schematically indicated brake activating member 8a, Which may be a brake pedal or a brake lever.

A cooling system is used to cool the combustion engine 2 and the oil retarder 6. Thecooling system comprises a first cooling circuit A Which is primary used to cool thecombustion engine 2. The first cooling circuit comprises an engine inlet line 10 inWhich a first coolant pump 9 is arranged. The first coolant pump 9 may be amechanical pump driven by the combustion engine 2. The first coolant pump 9 is ableto circulate coolant in the first circuit A. The first coolant pump 9 circulates coolantfrom the engine inlet line 10 to cooling channels in the combustion engine 2. Theengine circuit comprises an engine outlet line 11 receiving coolant from thecombustion engine 2. The engine outlet line 11 directs the coolant to a therrnostat 12.In this case, the therrnostat 12 is a valve controlled by the control unit 8. Thetherrnostat 12 directs coolant to a radiator bypass 13 and back to the engine inlet line10 When the coolant has a lower temperature than a regulating temperature of the therrnostat 12. The therrnostat 12 directs coolant, via a therrnostat outlet line 14, to a control valve 15, when the coolant has a higher temperature than the regulatingtemperature. The control valve 15 is arranged in a connection point between the firstcircuit A and the second circuit B. The control valve 15 is controlled by the controlunit 8. Fig. 1 shows the control valve 15 in a first position in which it directs thecoolant from the engine outlet line 11, via a first radiator inlet line 16, to a first radiator17. The coolant is cooled in the first radiator 17 by a cooling air ﬂow forced throughthe radiator 17 by ram air and a first radiator fan 17a. The coolant leaves the firstradiator 17 via a first radiator outlet line 18. The first radiator outlet line 18 directs the coolant back to the engine inlet line 10.

The cooling system comprises a second cooling circuit B which is primary used to coolthe oil retarder 6. The second circuit B comprises a retarder cooler inlet line 19directing coolant to an oil cooler 20 in which the coolant cools retarder oil which usedas Working ﬂuid in the oil retarder 6. A retarder cooler outlet line 21 receives coolantfrom the retarder cooler 20. The retarder outlet line 21 directs coolant to a secondcoolant pump 22. The second coolant pump 22 is able to circulate coolant in thesecond circuit. The control unit 8 controls the second coolant pump 22. The secondcoolant pump 22 may be an electric coolant pump. The second coolant pump 22 directsthe coolant, via a second radiator inlet line 23, to a second radiator 24. The secondradiator 24 and the first radiator 16 may be arranged in a common plane at a frontportion of the vehicle 1. The coolant is cooled in the second radiator 24 by a coolingair ﬂow forced through the second radiator 24 by ram air and a second radiator fan24a. The second cooling circuit B comprises a second radiator outlet line 25 directingcoolant from the second radiator 24 to the control valve 15. The control valve 15 directs the coolant to the retarder cooler inlet line 19 when it is in the first position.

The control unit 8 controls the control valve 15 and the second coolant pump 22 inview of information about operating parameters related to the temperature of thecombustion engine 2 and the water retarder 6. In this case, the control unit 8 receivesinformation from a first temperature sensor 26 sensing the temperature in the engineoutlet line 11, from a second temperature sensor 27 sensing the temperature in the first radiator outlet line 18, a third temperature sensor 28 sensing the temperature of the coolant in the retarder Cooler Outlet line 21 and a fourth temperature sensor 29 sensing the temperature of the coolant in the second radiator outlet line 25.

Fig. 1 shows an operating condition when the control valve 15 is in the first position.In the first position, the first circuit A and the second circuits B forrn two separate ﬂowpaths for the coolant. Fig. 2 shows an operating condition when the control valve 15 ina second position. In the second position, the control valve 15 directs the coolant fromthe engine outlet line 11 of the first cooling circuit A to the retarder cooler inlet line 19of the second circuit B. At the same time, the control valve 15 directs coolant from thesecond radiator outlet line 25 of the second circuit B to the first radiator inlet line 16 ofthe first circuit A. In the second position, the coolant in the first circuit A is directed tothe second circuit B when it reaches the control valve 15 and the coolant in the secondcircuit B is directed to the first circuit A when it reaches the control valve 15. Thus,when the control valve 15 is in the second position, a common ﬂow path is formed forthe coolant in which it ﬂows in series through the first cooling circuit A and the second cooling circuit B.

The first coolant pump 9 starts the circulation of coolant in the first circuit A as soonas the combustion engine 2 starts. The control valve 15 in the first position. Duringfollowing operating conditions, the control unit 8 receives substantially continuouslyinformation from the brake control unit 8a indicating whether the retarder 6 is not to beengaged or not. Furthermore, the control unit 8 receives information from the firsttemperature sensor 26 about the temperature of the coolant leaving the combustionengine 2, from the second temperature sensor 27 about the temperature of the coolantleaving the first radiator 17, from the third temperature sensor 28 about thetemperature of the coolant leaving the retarder cooler 20 and the fourth temperature sensor 29 about the temperature of the coolant leaving the second radiator 24.

After a cold start of the combustion engine the coolant in the first circuit A has a lowertemperature than the regulating temperature of the therrnostat 12. In view of that fact,the therrnostat 12directs the coolant from the engine outlet line 11 to the first radiator bypass line 13. When the coolant in the engine outlet line 11 has been heated to a temperature corresponding to the regulating temperature of the therrnostat 12, thetherrnostat 12 directs the coolant, Via the control valve 15, to the first radiator 17. Thecontrol unit 8 deterrnines if the coolant temperature in the engine outlet line 11 isbelow a maximum acceptable temperature, which may be 115°C, and if the coolanttemperature in the engine line 10 is below a maximum acceptable temperature, whichmay be 105 °C. If this is the case, it is enough to use the first radiator 17 and the firstcircuit A for cooling the combustion engine 2. In this case, the cooling system operates in an engine low mode.

As soon as the first temperature sensor 26 or the second temperature sensor 27indicates that the temperature of the coolant has reached to any of the above mentionedmaximum acceptable temperature, it is necessary to increase the cooling capacity ofthe combustion engine 2. The control unit 8 sets the control valve 15 in the secondposition such that the coolant in the engine outlet line 11 of the first circuit A isdirected to the retarder cooler inlet line 19 of the second circuit B. The coolant flowsfrom the retarder cooler inlet line 19 to the retarder cooler 20. The coolant is not heatedin the retarder cooler 20 since the oil retarder 6 is disengaged. The coolant leaving theretarder cooler 20 enters a retarder outlet line 21. The retarder outlet line 21 directs thecoolant to the second coolant pump 22. The second coolant pump 22 circulates thecoolant, via the second radiator inlet line 23, to the second radiator 24 where thecoolant is cooled in a first step. The coolant leaving the second radiator 24 is directed,via the second radiator outlet line 25, to the control valve 15. The control valve 15directs the coolant back to the first circuit A. The coolant leaving the control valve 15enters, via the first radiator inlet line 16, the first radiator 17 where the coolant iscooled in a second step. The coolant leaving the first radiator 17 is directed, via thefirst radiator outlet line 18, the engine inlet line and the first coolant pump 9, to thecombustion engine 2. The cooling of the coolant in the first radiator 17 and the secondradiator 24 increases the cooling capacity of the cooling system during operatingconditions when the load on the combustion engine 2 is high and the retarder 6 is disengaged.

In this case, the Cooling system operates in an engine high mode. The increasedcooling capacity makes it possible to prevent that the temperature of the coolantdirected to the combustion engine does not exceed 105°C and the temperature of thecoolant leaving the combustion engine does not exceed 115°C. The control unit 8 canswitch the control valve 15 between the first position and the second position in orderto maintain a desired operating temperature of the combustion engine 2. The controlunit 8 may also control the speed of the second coolant pump 22 such that a desiredcoolant ﬂow is obtained through the radiators 17, 24. The control unit 8 may alsocontrol the speed of the radiator fans 22 such that the coolant receives a desired temperature drop the radiators 17, 24.

As soon as the control unit 8 receives information from the brake activating member8a indicating that the retarder is to be engaged, it sets the retarder valve 6a in an openposition such that an oil ﬂow is directed to the oil retarder 6. At the same time, thecontrol unit 8 sets the control valve 15 in the f1rst position such that the coolant ﬂowsin the first circuit A and the second circuit B are separated. When the retarder 6 isengaged, the combustion engine 2 operates at an idle speed and there is substantiallyno cooling demand of the combustion engine 2 in the first circuit A. On the other hand,the retarder may provide a high load on the second circuit B. Conventional coolants used in cooling system can be heated to temperature of about 160°C.

In view of that fact, it is possible to allow a coolant temperature in the retarder cooleroutlet line 21 up to 160 °C and a coolant temperature of about 140 °C in the retarderinlet line 19. The cooling capacity of the second circuit B is related to the coolanttemperature drop in the second radiator 24. The coolant temperature drop in the secondradiator 24 is related temperature difference between the coolant and ambient airforced through the second radiator 24. Since it is possible to allow a coolanttemperature of about 160°C in the second circuit, it is possible to provide an increasedcoolant temperature drop in the second radiator 24 and a more efficient cooling of theretarder oil in the retarder cooler 20. In order to further control the cooling capacity inthe second circuit B when the oil retarder 6 is engaged, the control unit 8 may control the speed of the second coolant pump 22 and thus the coolant ﬂow rate through the 11 second radiator 24 and the cooling air ﬂow rate through the second radiator 24 bymeans of the second radiator fan 24a. In this case, the cooling system operates in a retarder mode.

As soon as the control unit 8 receives information from the brake actiVating member8a indicating that the retarder is to be disengaged, it sets the retarder Valve 6a in aclosed position such that the oil ﬂow to the oil retarder 6 ceases. Furthermore, thecontrol unit 8 receives information from the first temperature sensor 26 about thetemperature of the coolant in the engine outlet line 11 which corresponds to thetemperature of the combustion engine 2. In case the retarder 6 has been engaged duringa long period of time, the temperature of the combustion engine 2 has probablydropped to a temperature below a desired operating temperature. In order to increasethe coolant temperature in the first circuit A and heat the combustion engine 2, thecontrol unit 8 sets the therrnostat 12 in the second position such that the control Valve15 directs Warm coolant from the second circuit B to the first circuit A and coldcoolant from the first circuit A to the second circuit B. Such a mixing of the coolants inthe first circuit A and the second circuit B results in a rapid heating of the coolant inthe first circuit A and the combustion engine 2 to a desired operating temperature.Furthermore, the temperature of the coolant in the second circuit B receives acorresponding rapid cooling. In this case, the cooling system operates in an afterretarder mode. During long periods of hard braking where maximum brake power isneeded, e. g. on long downhill slopes, the control Valve 15 should ensure that thetemperature in the outlet line should be held at approximately 115°C for maximumperformance. If the temperature in the outlet line 11 drops below 115°C, the controlvalve 15 should introduce a suitable amount of warrner coolant from circuit B to circuit A.

Fig 3 shows an altemative cooling system. In this case, the second object is a waterretarder 6. Thus, coolant is used as cooling ﬂuid as well as working ﬂuid in theretarder 6. A retarder Valve 6a directs the coolant from a retarder inlet line 19 to aretarder bypass line 30 when the retarder is disengaged and to the water retarder 6 when the retarder is engaged. When the water retarder 6 is engaged, it acts as a pump 12 with a high pump capacity. In this case, there is no need to use a coolant pump 22 inthe second circuit B. Furthermore, the cooling system comprises a multi control Valve31 which is controlled by the control unit 8. The multi control Valve 31 is able to bemoved to a first position and a second position in a corresponding manner as thecontrol Valve in Figs 1 and 2. Furthermore, the multi control Valve 31 is also able to beset in additional positions between the first position and the second position such that itdirects Variable amounts of coolant between the circuits A, B in a stepless manner.Finally, the multi control Valve 31 is also able to operate as a therrnostat and directcoolant to the first radiator bypass line 13 or the first radiator 17 by means of thecontrol unit 8. Except the above mentioned differences, the cooling system in Fig. 3 has a corresponding design and function as the cooling system shown in Figs. 1 and 2.

The invention is not restricted to the described embodiment but may be Varied freelywithin the scope of the claims. It is possible that the cooling system comprises three ormore circuits, which each comprises a radiator and a component to be cooled, which are temporarily separated or connected in series by means of a control Valve.

Claims

13 Claims

1. l. Cooling system for cooling of two objects to different temperatures, wherein thecooling system comprises an first cooling Circuit (A) Which comprises a first Coolantcirculating member (9), a first radiator (17) and a first object (2) to be cooled, and asecond Circuit (B) which comprises a second Coolant circulating member (6, 22), asecond radiator (24) and a second object (6, 20) capable to be heated to a highertemperature than the first object, characterized in that the cooling system comprises acontrol Valve (l5, 3 l) which, in a first position, is configured to form separate ﬂowpaths for the Coolant in first Circuit (A) and in the second Circuit (B), and in a secondposition configured to form a common ﬂow path for the Coolant through first Circuit(A) and in the second Circuit (B) such that the Coolant ﬂows in series through the first radiator (l7) and the second radiator (24).

2. Cooling system according to claim l, characterized in that the control Valve (l5, 3 l)is, in the first position, configured to direct Coolant from the first object (2) towards thefirst radiator (l7) at the same time as it direct Coolant from the second radiator (24) towards the second object (6, 20).

3. Cooling system according to claims l or 2, characterized in that the control Valve is,in the second position, configured to direct Coolant from the first object (2) towards thesecond object (6, 20) at the same time as it directs Coolant from the second radiator (24) towards the first radiator (l7).

4. Cooling system according to any one of the preceding claims, characterized in thatthe control Valve (l5, 3 l) comprises a Valve body (l5a) movably arranged to the first position and the second position.

5. Cooling system according to any one of the preceding claims, characterized in thatthe control Valve (3 l) is settable in at least one additional position in which it directs apart of the Coolant ﬂow from the first Circuit (A) to the second Circuit (B) and a correspond part of the Coolant from the second Circuit (B) to the first Circuit (A). 14

6. Cooling system according to any one of the preceding claims, characterized in that the control valve (3 l) includes a therrnostat.

7. Cooling system according to any one of the preceding claims, characterized in thatthe cooling system comprises a control unit (8) conf1gured to control the position of the control Valve (15 , 3 l).

8. Cooling system according to claim 7, characterized in that the control unit (8) isconfigured to control the positioning of the control Valve (l5, 3 l) by means of inforrnation about a parameter related to the temperature of the first object (2).

9. Cooling system according to claim 7 or 8, characterized in that the control unit (8) isconfigured to control the positioning of the control Valve (l5, 3 l) by means ofinforrnation about a parameter related to the temperature of the coolant entering the first object (2).

10. l0. Cooling system according to any one of the preceding claims 7 to 9, characterizedm that the control unit (8) is conf1gured to control the positioning of the control Valve (l5, 3 l) by a parameter related to the temperature of the second object (6, 20).

11. ll. Cooling system according to any one of the preceding claims 7 to l0, characterizedm that the control unit (8) is conf1gured to control the positioning of the control Valve(l5, 3 l) by means of inforrnation about a parameter related to the temperature of the coolant entering the second object (6, 20).

12. l2. Cooling system according to any one of the preceding claims 7 to ll, characterizedm that the control unit (8) is configured to control the positioning of the control Valve(l5, 3 l) in order to create a maximum acceptable temperature in the respective circuits (A, B).

13. Cooling system according to any one of the preceding clainis, characterized in that the second object (6) is an object Which is teniporarily engaged.

14. Cooling system according to system according to any one of the preceding clainis, characterized in that the first object is an engine (2).

15. A Vehicle coniprising a cooling systeni according to any one of the preceding clainis 1-14.