SE535564C2 - Cooling system in a vehicle - Google Patents

Abstract

A cooling system with a circulating coolant for cooling a combustion engine in a vehicle (1) includes a first radiator (13), a first line circuit (14, 15, 16) which leads coolant from the first radiator (13) to the engine (2); a second line circuit (17, 18) which leads coolant from the engine (2) to the first radiator (13); a second radiator (20) upstream of the first radiator (13) in air flow through radiators; a third line circuit (21, 22, 24) including at least one line (21, 24) to lead coolant from a line (16) in the first line circuit to the second radiator (20), and a fourth line circuit (25, 26a-d, 27) which leads coolant from the second radiator (20) to the first line circuit (15) and which contains at least one cooler (29, 30, 31) for cooling a medium or component of the vehicle (1).

Description

535 564 is led to the internal combustion engine. The compressed air is usually cooled in a charge air cooler located at a front of a vehicle. Thus, the compressed air can be cooled to a temperature which substantially corresponds to the ambient temperature. Under cool weather conditions, the compressed air in the charge cooler is cooled to a temperature that may be lower than the dew point temperature of the air. This precipitates water vapor in the liquid form in the charge cooler. As the ambient air temperature is lower than 0 ° C, there is also a risk that the precipitated water freezes to ice inside the charge air cooler. Such icing means that the flue channels' flow channels inside the charge cooler are more or less clogged, which results in a reduced flow of flue to the internal combustion engine with operating disturbances or stops as a result.

Through the technology called EGR (Exhaust Gas Recirculation), it is known to recirculate some of the exhaust gases from a combustion process in an internal combustion engine.

The recirculating exhaust gases are mixed with the inlet hood of the internal combustion engine before being led to the internal combustion engine. The addition of exhaust gases in the air gives a lower combustion temperature, which i.a. results in a reduced content of nitrogen oxides NOX in the exhaust gases. This technology is used for both otto engines and for diesel engines. The recirculating exhaust gases are cooled in at least one EGR cooler before being mixed with the inlet hood. It is known to use EGR coolers in which the recirculating exhaust gases are cooled to a temperature which substantially corresponds to the ambient temperature.

Exhaust gases contain water vapor that condenses inside the EGR cooler when the exhaust gases are cooled to a temperature that is lower than the dew point of the water vapor. In cases where the ambient air temperature is below 0 ° C, there is also a risk that the condensed water freezes to ice inside the EGR cooler. Such icing means that the exhaust ducts 'flow channels inside the EGR cooler are more or less clogged, which results in the exhaust gases' content of nitrogen oxides increasing.

SUMMARY OF THE INVENTION The object of the present invention is to provide a cooling system in a vehicle which enables a cooling of a large number of components in the vehicle to a low temperature.

Another purpose of the cooling system is that it should be able to withstand instantaneous peak loads. An additional feature of the cooling system is that it should be able to prevent ice formation in coolers that contain water vapor. The first of said objects is achieved with the cooling system of the kind mentioned in the introduction, which is characterized by the features stated in the characterizing part of claim 1. In the part of the cooling system referred to here as the first line circuit, the coolant has a relatively low temperature since it has been cooled in the coolant cooler. In the part of the cooling system referred to herein as the second line circuit, the coolant has a relatively high temperature because it has cooled the internal combustion engine. The cooling system of the present invention includes an additional conduit loop. The additional line loop comprises a second coolant cooler which is arranged in a position upstream of the ordinary coolant cooler and a third line circuit with which it is possible to lead relatively cold coolant from the first line circuit to the second coolant cooler. The first coolant cooler and the second coolant cooler are advantageously mounted in an area located at a front portion of the vehicle. The second coolant cooler is here located at least partially in front of the first coolant cooler. A lcylar fl genuine and the vehicle wind speed here produces an air flow in one direction so that it first passes through the second coolant cooler before passing through the first coolant cooler.

Thus, in this case, relatively cold coolant is taken from the first conduit circuit and led to a second coolant cooler where the coolant is cooled in a further step of air having a lower temperature than the air cooling the coolant in the first coolant cooler.

The coolant thus obtains a cooling in the second coolant cooler to a low temperature which under favorable circumstances may be in the vicinity of the temperature of the ambient air. The cold coolant leaving the second coolant cooler is led to a fourth conduit circuit where it cools at least one medium or component in a coolant cooled cooler. The cold coolant in the fourth line circuit is advantageously used to cool media or components that require cooling to a low temperature. In this case, the individual media or components need not have a radiator arranged at a front portion of the vehicle.

According to a preferred embodiment of the present invention, the fourth line circuit comprises at least two parallel lines which each comprise a cooler for cooling a respective medium or a respective component in the vehicle. The cold coolant in the fourth line circuit is advantageously used to cool several media or components that require cooling to a low temperature. By conducting the cold coolant in fl your parallel lines, each of which is equipped with a respective cooler, all media can be cooled by coolant with the same low temperature. However, it is possible to arrange one or more coolers in series with each other in the fourth line circuit.

According to another preferred embodiment of the present invention, the third conduit circuit comprises at least one conduit with which it is possible to conduct coolant from the second conduit circuit to the second coolant cooler. In this case, hot coolant is thus led to the other coolant cooler. This may be appropriate at times when the cooling system is heavily loaded. Thus, in this case, hot coolant is cooled in both the first coolant cooler and the second coolant cooler. The capacity of the cooling system can thus be increased to cope with instantaneous peak loads. The third conduit circuit advantageously comprises a valve means which in a first position conducts coolant å 'from a conduit in the first conduit circuit to the second coolant cooler and in a second position conducts coolant from a conduit in the second conduit circuit to the second coolant cooler. With such a valve means which can be a three-way valve, relatively cold coolant or hot coolant can alternatively be led to the second coolant cooler.

According to another preferred embodiment of the present invention, the cooling system comprises a control unit which is adapted to receive information from a sensor which senses a parameter which is related to the coolant temperature in the cooling system.

Said sensor advantageously senses the temperature of the coolant in the second line circuit where it has its highest temperature. The control unit may be a computer unit or the like which is provided with a suitable software for this task.

The control unit can set the valve means in the second position when it receives information from said sensor which indicates that the coolant has a higher temperature than a reference value. When the coolant temperature rises above a reference value which may be a maximum acceptable coolant temperature, in this case the Control Unit automatically leads hot coolant to the other coolant cooler as well. When the coolant temperature drops below a reference value, the control unit can again set the valve means in the first position when the extra cooling of the coolant is no longer needed. The cooling system may comprise a cooler for cooling a medium or a component in the second line circuit. Thus, in this case, the already hot coolant which cooled the internal combustion engine is used to cool an additional medium or component in the vehicle. This component can be an oil cooler for hydraulic oil used in a hydraulic retarder. At times when the vehicle is braked by means of a hydraulic retarder, the cooling system is exposed to a large instantaneous load. At times when the retarder is activated, the control unit can directly set the valve means in the second position so that hot coolant is led to the second coolant cooler to increase the capacity of the cooling system.

According to another preferred embodiment, the second coolant cooler is arranged in a position upstream of a cooler for cooling a gaseous medium containing water vapor. The gaseous medium which is led to the internal combustion engine may be charged or recirculating exhaust gases. The most diesel-powered internal combustion engines and many petrol-powered internal combustion engines are supercharged, ie. they include a turbocharger that sucks in and compressed ambient air that is led to the internal combustion engine. The compressed air thus contains water vapor in an amount that varies with the accuracy of the ambient air. Because the compressed air has a higher dew point than air with ambient pressure, water can condense in the charge air cooler.

The compressed air should therefore also not be cooled to a temperature below 0 ° C, as condensed water vapor can then freeze to ice inside the charge cooler.

The exhaust gases of the combustion engine also contain water vapor in an amount that varies with the humidity of the surrounding air. Recirculating exhaust gases also have a higher pressure than ambient lu fi. It is thus often difficult to prevent water vapor from condensing inside a lu yld-cooled EGR cooler. The recirculating exhaust gases should therefore also not be cooled to a temperature below 0 ° C as condensed water vapor in the EGR cooler in such cases freezes to ice.

According to another preferred embodiment, the cooling system comprises a control unit which is adapted to receive information from a sensor which senses a parameter related to whether icing or risk of icing is present in the cooler and to set the valve means in the second position when receiving information from said sensor which indicates that icing or the risk of icing is present in the radiator. Said sensor may be a temperature sensor which senses medium temperature when it has left the cooler. If the medium has a lower temperature than 0 ° C, ice will probably form inside the radiator. When the control unit receives such information, it places the valve means in the second position so that hot coolant is led to the second coolant cooler. The air flowing through the second coolant cooler thus obtains an elevated temperature. When this hot air reaches the downstream radiator, any ice that has formed inside the radiator melts. When the control unit receives information from said sensor which indicates that there is no longer a risk of icing, it puts the valve member back in the first position. According to another preferred embodiment of the invention, the fourth line circuit comprises a bypass line and a valve with which the coolant can be led past the line with said cooler. Hot coolant is thus passed through the second coolant cooler during times when the cooling system is heavily loaded and when icing is present in a cooler in the form of a charge air cooler or EGR cooler. During such occasions, it is also an advantage to increase the coolant flow through the second coolant cooler. With a bypass line, the coolant can be led past the coolers in the fourth line circuit. This reduces the pressure drop in the fourth line circuit with the result that the coolant flow through the second coolant cooler increases as well as the capacity of the cooling system.

BRIEF DESCRIPTION OF THE DRAWINGS In the following, as an example, preferred embodiments of the invention are described with reference to the accompanying drawings, in which: Fig. 1 shows a cooling system according to a first embodiment of the present invention and Fig. 2 shows a cooling system according to a second embodiment. of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION Fig. 1 shows a vehicle 1 driven by a supercharged internal combustion engine 2. The vehicle 1 may be a heavy vehicle driven by a supercharged diesel engine. The exhaust gases from the cylinders of the internal combustion engine 2 are led, via an exhaust gas collector 3, to an exhaust line 4.

The exhaust gases in the exhaust line 4, which have an overpressure, are led to a turbine 5 of a turbocharger. The turbine 5 then provides a driving force, which is transmitted, via a connection, to a compressor 6. The compressor 6 thereby compresses the air which, via a lamp 7, is led into an inlet line 8. A charge cooler 9 is arranged in the inlet line 8. The charge air cooler 9 is arranged in an area A at a front part of the vehicle 1. The task of the charge air cooler 9 is to cool the compressed air before it is led to the internal combustion engine 2. The compressed air is cooled in the charge air cooler 9 by air forced through the charge air cooler 9 by means of a radiator fl .

The cooling shaft 10 is driven by the internal combustion engine 2 by means of a suitable connection. 535 564 The internal combustion engine 2 is cooled by coolant circulating in a cooling system. The coolant is circulated in the cooling system by means of a coolant pump 11. The cooling system also comprises a thermostat 12. The coolant in the cooling system is intended to be cooled in a first coolant cooler 13, which is mounted at a farther part of the vehicle 1 in area A. The first coolant cooler 13 is mounted downstream the charge air cooler 9 with respect to the flow direction of the cooling air in the control area A. The cooling system comprises a first line circuit in the form of lines 14, 15, 16 which conduct the coolant from the first coolant cooler 13 to the internal combustion engine 2. The coolant pump 11 is arranged in line 16. The cooling system comprises a second line circuit in the form of lines 17, 18 which conduct the coolant from the internal combustion engine 2 to the first coolant cooler 13.

The line 17 comprises a retarder cooler 19 for cooling hydraulic oil which is used in a retarder. At times when the coolant has too low a temperature, the thermostat 12 directs the coolant from the line 17, via the lines 15, 16 to the internal combustion engine 2. In this case, the coolant is thus not cooled in the first coolant cooler 13.

The cooling system includes an extra cable loop. The auxiliary line loop comprises a third line circuit leading coolant to a second coolant cooler 20. The third line circuit comprises a line 21 which is connected to the line 16 of the first line circuit and a line 22 which is connected to the line 17 of the second line circuit. The third line circuit comprises a three-way valve 23. When the three-way valve 23 is set in a first position, the relatively cold coolant from line 21 and a line 24 lead to the second coolant cooler 20. When the three-way valve 23 is set in a second position, the hot coolant from line 22 and The line 24 to the second coolant cooler 20. The second coolant cooler 20 is arranged at the iron portion of the vehicle 1 in a position upstream of the first coolant cooler 13 and upstream of the charge air cooler 9 with respect to the direction of the cooling air flow in the area A. cold coolant from the second coolant cooler 20 to the line 15 of the first line circuit. The fourth conductor circuit includes an initial common conductor. The common line 25 is split into four parallel lines 26a-d. The four parallel lines 26a.d merge into a common line 27 which leads the coolant to the line 15 of the first line circuit.

The first parallel line constitutes a bypass line 26a which is provided with a valve 27 with which the flow through the bypass line 26a can be regulated. The second parallel line 26b comprises a cooler in the form of a condenser 29 of an AC system in the vehicle 1. The coolant cools a circulating refrigerant in the condenser 29 to a temperature at which it condenses. The third parallel line 26c comprises a cooler 30 for cooling servo oil in the vehicle 1. The fourth parallel line 26d comprises a cooler 31 for cooling servo oil in the vehicle 1. All these media require a cooling to a low temperature. The cooling system includes a control unit 32 for controlling the three-way valve 22 and the valve 28. The control unit 32 receives information from a first temperature sensor 33 which senses the temperature of the coolant in line 17 in a position downstream of the retarder cooler 19 and a second temperature sensor 34 which senses charge air temperature in inlet line it is cooled in the charge cooler 9.

During operation of the vehicle, the coolant pump 11 circulates coolant in the cooling system.

The control unit 32 receives substantially continuous information from the temperature sensor 33 regarding the temperature of the coolant in the line 17 and regarding the temperature of the charge air when it leaves the charge air cooler 9. At times when the coolant has an acceptable temperature below a reference value in the first mode. When the three-way valve 32 is in the first position, the coolant pump 11 leads a part of the coolant in the line 16 to the dry combustion engine 2. This part of the coolant is then led through the retarder cooler 19 and lines 17 and 18 to the first coolant cooler 13. A remaining part of the coolant leads the coolant pump 1 1 via line 21, three-way valve 23 and line 24, to the second coolant cooler 20. This part of the coolant is cooled in the second coolant cooler 20 by lu fi at ambient temperature.

The coolant leaving the second coolant cooler 20 may thus have a temperature in the vicinity of the ambient temperature. The cold coolant is led from the second coolant cooler 20 to the line 25. In this case, the control unit keeps the valve 28 in a closed position. Thus, the cold coolant from the line 25 will be led in parallel through the three lines 26b-d where it cools the coolant in the condenser 29, the gearbox oil in the cooler 30 and the servo oil in the cooler 31. These media provide a very good cooling of the cold coolant. The coolant fi from the parallel lines 26b-d is collected in the line 27 which leads the coolant to the line 15 and the coolant pump 1 1.

If the control unit 32 receives information indicating that the coolant temperature has risen above the reference value, a higher capacity of the cooling system is required. The fact that the coolant temperature rises above the reference value may be due to the vehicle braking with the help of the hydraulic retarder. The cooling system is heavily loaded as the coolant also 535 554 must cool the oil retarder cooler 19. In this case the control unit 32 sets the three-way valve 23 in the second position. Thus, a part of the hot coolant in the line 17 will be led, via the line 22, the three-way valve 23 and the line 24, to the second coolant cooler 20. In this case, hot coolant is thus cooled in both the first coolant cooler 13 and in the second coolant cooler 20. This results in a larger temperature difference between the coolant and the lu in the second coolant cooler 20.

The cooling system's capacity to cool the coolant increases. To further increase the capacity of the cooling system, the control unit 32 can open the valve 28 so that the cold coolant leaving the second coolant cooler 20 is mainly passed through the bypass line 28.

This reduces the flow resistance of the cold coolant in the extra line loop. The coolant flow through the second coolant cooler 20 increases, resulting in a further increased capacity of the cooling system. When the control unit 32 receives information indicating that the temperature of the coolant has dropped to an acceptable level below a reference value, it closes the valve 28 and sets the three-way valve 23 in the first position.

If the control unit 32 receives information from the temperature sensor 34 which indicates that the charge air has a temperature lower than 0 ° C, the control unit 32 determines that ice is formed in the charge cooler. The control unit 32 sets the three-way valve 23 in the second position. Thus, a part of the hot coolant in the line 17 will be led via the line 22, the three-way valve 23 and the line 24 to the second coolant cooler 20. Thus, the air flowing through the second coolant cooler 20 obtains a marked temperature increase of the hot coolant before it reaches it. the downstream charge air cooler 9. The air reaching the charge air cooler 9 now has a clearly higher temperature than 0 ° C. Thus, any ice that has formed inside the charge air cooler 9 will melt.

To further increase the defrosting capacity of the cooling system, the control unit 32 can open the valve 28 so that the cold coolant leaving the second coolant cooler 20 is mainly led through the bypass line 28. Thus, the flow resistance of the cold coolant through the additional loop decreases. The flow of hot coolant through the second coolant cooler 20 increases, resulting in a further improved defrosting of the charge liquor cooler 9. When the control unit 32 receives information indicating that the charge of the charge cap has risen again to an acceptable level, it sets the valve 28 in the closed position and the three-way valve 23 in the first mode.

Fig. 2 shows an alternative cooling system. In this case, the dry combustion engine 2 is equipped with an EGR (Exhaust Gas Recirculation) system for recirculation of the exhaust gases. A 535 554 return line 35 for recirculating exhaust gases here extends from the exhaust line 4 to the inlet line 8. The return line 35 comprises an EGR valve 36, with which the exhaust gas flow in the return line 35 can be switched off. The EGR valve 36 can also be used to steplessly control the amount of exhaust gases led from the exhaust line 4, via the return line 35, to the inlet line 8. The return line 35 comprises an EGR cooler 37 for cooling the exhaust gases. Before they are mixed with the charge air in the inlet line 8 and led to the internal combustion engine 2. In this case, the control unit 32 also receives information from a temperature sensor 38 which senses the temperature of the recirculating exhaust gases after they have been cooled in the EGR cooler 37.

During operation of the internal combustion engine 2, the control unit 32 receives information from the temperature sensor 38 regarding the temperature of the recirculating exhaust gases after they have been cooled in the second EGR cooler 37. The control unit 32 compares received temperature values with a reference temperature. To prevent icing in the second EGR cooler 37, a reference temperature of 0 ° C can be used. As long as the control unit 32 receives information from the first temperature sensor 38 that the recirculating exhaust gases have a temperature above the reference temperature, the control unit 32 sets the valve means in the first position. If the control unit 32 receives information from the temperature sensor 38 indicating that the recirculating exhaust gases have been cooled to a temperature below the reference temperature, the control unit 32 sets the valve means 23 in the second position. Thus, some of the hot coolant in line 17 will be led via line 22, the three-way valve 23 and the line 24 to the second coolant cooler 20. The air flowing through the second coolant cooler 20 will obtain a marked temperature increase before it reaches the downstream EGR cooler 37. The lu that reaches the EGR cooler 37 now has a clearly higher temperature than 0 ° C. Thus, any ice that has formed inside the EGR cooler 37 will melt. When the control unit 32 receives information indicating that the temperature of the recirculating exhaust gases has risen again to an acceptable level, it sets the three-way valve 23 in the first position.

Otherwise, this embodiment has the same properties as the embodiment in Figs. 1 in addition to the fact that it lacks a bypass line 28. When the three-way valve 23 is in the first position, a good cooling of the coolant in the second coolant cooler 20 is thus also provided here. in the radiator 30 and servo oil in the radiator 31. At times when the coolant has too high a temperature, the three-way valve 23 can be set in the second position so that hot coolant is passed through the second coolant cooler 20 in order to increase the capacity of the cooling system. On occasions when the charge air has a too low temperature when it leaves the charge air cooler 9, the three-way valve 32 is also set in the second position. In this case, hot coolant is passed through the second coolant cooler 20 for the purpose of defrosting the downstream charge air cooler 9.

The invention is in no way limited to the described embodiments but can be varied freely within the scope of the claims.

Claims (8)

10 15 20 25 30 35 535 564 12, Patent claim A cooling system with a circulating coolant for cooling an internal combustion engine in a vehicle (1), the cooling system comprising a first coolant cooler (13) where the coolant is cooled by an air stream led in a certain direction through the radiator, a first line circuit (14 , 15, 16) which conveys coolant from the first coolant cooler (13) to the internal combustion engine (2) a second line circuit (17, 18) which conveys coolant from the internal combustion engine (2) to the first coolant cooler (13), a second coolant cooler (20) arranged in a position upstream of the first coolant cooler (13) with respect to the direction of the cooling air flow so that at least a part of the air flowing through the second coolant cooler (20) also flows through the first coolant cooler (13), a third line circuit (21, 22, 24) comprising at least one conduit (21, 24) with which it is possible to conduct coolant from a conduit (16) in the first conduit circuit to the second coolant cooler (20). and a fourth conductor circuit (25, 26a-d, 27) which directs coolant from the second coolant cooler (20) to the first conduit circuit (15), the fourth conductor circuit (25, 26a-d, 27) comprising at least one cooler (29 , 30, 31) for cooling a medium or a component in the vehicle (1), characterized in that the third line circuit (21, 22, 24) comprises at least one line (22, 24) with which it is possible to conduct coolant from a conduit (17) in the second conduit circuit to the second coolant cooler (20) and that the third conductor circuit (21, 22, 24) comprises a valve means (23) which in a first position conducts coolant from the conduit (16) in the first conduit circuit (14, 15, 16) to the second coolant cooler (20) and in a second position coolant leads from the line (17) in the second line circuit (17, 18) to the second coolant cooler (20). Cooling system according to claim 1, characterized in that the fourth line circuit (25, 26a-d, 27) comprises at least two parallel lines (26b-d) each comprising a cooler (29, 30, 31) for cooling a respective medium or a respective component of the vehicle (1). Cooling system according to claim 1 or 2, characterized in that the cooling system comprises a control unit (32) which is adapted to receive information from a sensor (33) which senses a parameter which is related to the temperature of the coolant in the cooling system. 10 15 20 25 30 535 584 lö Cooling system according to claim 3, characterized in that the control unit (32) is adapted to set the valve means (23) in the second position when it receives information from said sensor (33) which indicates that the coolant has a higher temperature than a reference value. Cooling system according to one of the preceding claims, characterized in that the cooling system comprises a cooler (19) for cooling a medium or a component in the second line circuit (17, 18). Cooling system according to one of the preceding claims, characterized in that the second coolant cooler (20) is arranged in a position in the vehicle (1) upstream of a cooler (9, 37) for cooling a gaseous medium containing water vapor with respect to the cooling lu fl the direction of the flow so that at least a part of the air flowing through the second coolant cooler (20) also flows through said cooler (9, 37). Cooling system according to claim 6, characterized in that it comprises a control unit (32) adapted to receive information from a sensor (34, 38) which senses a parameter which is related to whether icing or risk of icing is present in the cooler (9). , 37) and to set the valve means (32) in the second position when it receives information from said sensor (34, 38) indicating that icing or risk of icing is present in the radiator (9, 37). Cooling system according to one of the preceding claims, characterized in that the fourth line circuit (25, 26a-d, 27) comprises a bypass line (26a) and a valve (29) with which the coolant can be led through the bypass line (26a) and thus past the line. (26b-d) with said cooler (29, 30, 31).