SE0950779A1 - Arrangement for cooling compressed air which is led to an internal combustion engine - Google Patents

Abstract

The present invention relates to an arrangement for cooling compressed air which is led to an internal combustion engine (2) in a vehicle (1). The arrangement comprises an air-cooled charge air cooler (10) which comprises an inlet tank (10a), a cooling portion (10b) and an outlet tank (10c). The cooling portion (10b) is arranged in a space (17) located between the inlet tank (10a) and the outlet tank (10c). The arrangement also comprises a cooling system comprising a line circuit (12) with a circulating coolant, a charge air cooler (9) where the circulating coolant is adapted to cool the compressed air in a first step before it is cooled in the air cooled charge air cooler (10). in a second stage and a cooler element (13) where the circulating coolant is adapted to cool exhaust air. The cooler element (13) is arranged in a part of the space (17a) between the inlet tank (10a) and the outlet tank (10c) which is not occupied by the cooling portion (10b). (Fig. 2)

Description

Another problem with an air-cooled charge air cooler is that the flow losses of the compressed air in the charge air cooler can be relatively large, especially if very hot air with a low density is to be cooled in the charge air cooler.

SUMMARY OF THE INVENTION The object of the present invention is to provide an arrangement of the kind mentioned in the introduction which enables an efficient cooling of compressed air which is led to an internal combustion engine by means of a space-consuming construction and where the compressed air receives relatively moderate pressure losses. ningen.

This object is achieved with the arrangement of the kind mentioned in the introduction, which is characterized by the features stated in the characterizing part of claim 1. Compressed air is cooled more efficiently in a coolant-cooled charge air cooler than in an air-cooled charge air cooler. This is because liquids have a significantly higher density than gases. The flow ducts of the compressed air in a coolant-cooled charge air cooler can thus be made shorter than in an air-cooled charge air cooler with a corresponding cooling capacity. With shorter flow channels, smaller flow losses and a lower pressure drop are obtained. In this case, a coolant-cooled charge air cooler is thus used to cool the compressed air in a first step. Thus, the compressed air provides relatively small flow losses in an initial stage when it is cooled in the coolant-cooled charge air cooler. Cooling the compressed air in a coolant-cooled charge air cooler in a first stage when it has a high temperature and a low density is particularly advantageous as the compressed air in this state obtains particularly high flow losses in an air-cooled charge air cooler.

In this case, a smaller air-cooled charge air cooler can thus be used to cool the compressed air in the second stage. The cooling part of the charge air cooler can thus be reduced in size. However, the inlet tank and the outlet tank of the air-cooled charge air cooler do not need to be reduced in size. When the cooling portion is reduced in size, a space is exposed between the inlet tank and the outlet tank which is flowed through by cooling air. According to the present invention, this exposed space is used for applying a cooler element for cooling the circulating coolant which cools the compressed air in the coolant-cooled charge air cooler. In this way a compact construction can be obtained which utilizes available cooling space at the same time as the compressed air can be cooled to a low temperature with relatively low pressure losses.

According to a preferred embodiment of the present invention, the cooler element is arranged in a position above the cooling portion in said space between the inlet tank and the outlet tank. By arranging the radiator element above the cooling part of the charge air cooler, wiring of lines to and from the radiator element and the charge air cooler is simplified. However, it is possible to alternatively arrange the cooling portion at an upper portion and arrange the cooling element in a space between the inlet tank and the outlet tank in a position below the cooling portion. The above-mentioned definitions regarding the relative positions of the radiator element and the cooling section in height refer, of course, to their positions when they are in a mounted condition in a vehicle.

According to an embodiment of the present invention, the cooler element comprises an inlet tank adapted to receive coolant to be cooled, a cooling portion where the coolant is adapted to be cooled by air flowing through the cooling portion and an outlet tank adapted to receive the cooled the coolant. In this case, the radiator element has a substantially corresponding construction as the air-cooled charge air cooler. All constituent portions of the radiator element are advantageously arranged in said space between the inlet tank of the charge air cooler and the outlet tank. Preferably, the radiator element has a size so that it fills a maximum of the space between the inlet tank and the outlet tank which is not occupied by the radiator portion of the charge air tank. Thus, the cooling air flow in the space can be utilized optimally for cooling the coolant in the cooler element and the compressed air in the air-cooled charge air cooler.

According to an embodiment of the present invention, said cooling system comprises a pump which is adapted to circulate the coolant in the cooling system at a variable speed.

With such a pump, the coolant flow in the cooling system can be varied. As the coolant fl fate increases, the compressed air obtains a higher cooling effect in the first charge air cooler.

The arrangement advantageously comprises a control unit which is adapted to control the speed of the pump during operation of the internal combustion engine. Such a control unit may be a computer unit or similar component which includes suitable software for this purpose.

The control unit may be adapted to control the pump by means of information regarding at least one parameter which is related to the temperature which the compressed air obtains after the cooling in the coolant-cooled charge air cooler or after the cooling in the air-cooled charge air cooler. By varying the speed of the pump in a suitable way, the compressed air can in most circumstances obtain a desired temperature when it is led to the internal combustion engine.

According to an embodiment of the present invention, the control unit is adapted to receive information regarding a parameter which is related to the load of the internal combustion engine. The higher the load on the internal combustion engine, the more the air is compressed by the compressor of a turbocharger before it is led to the internal combustion engine and the higher the temperature the compressed air receives. The load of the internal combustion engine is thus related to how the temperature of the air after compaction and how much it needs to be cooled before it is led to the internal combustion engine. The control unit may be adapted to receive information from a sensor which senses the temperature of the cooling air stream flowing through the space between the inlet tank and the outlet tank. The cooling effect that the compressed air obtains in the first charge air cooler and in the second charge air cooler is related to the temperature and velocity of the cooling air stream. Using this information, the control unit can select a suitable speed of the pump which results in the compressed air being cooled in the coolant-cooled charge air cooler and in the air-cooled charge air cooler to a desired temperature before it is led to the internal combustion engine.

According to another preferred embodiment of the present invention, the air-cooled charge air cooler and the radiator element are arranged in an area of the vehicle where they are permeated by air with ambient temperature during operation of the internal combustion engine.

This allows the compressed air to be cooled to a temperature close to the ambient temperature. The air-cooled charge air cooler and the radiator element may be arranged at a front portion of the vehicle in a position in front of the vehicle's ordinary radiator for cooling the coolant in a cooling system which cools the internal combustion engine. In this case, an ordinary radiator fl genuine in the vehicle can be used to suck ambient air through the radiator element and the air-cooled charge air cooler.

BRIEF DESCRIPTION OF THE DRAWINGS In the following, as an example, a preferred embodiment of the invention is described with reference to the accompanying drawings, in which: Figs. Fig. 1 shows an arrangement according to an embodiment of the present invention and Fig. 2 shows a front view of the air-cooled charge air cooler and the cooler element in the plane B-B in Fig. 1.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION Fig. 1 schematically shows a vehicle 1, which is advantageously a heavy vehicle, which is driven by an internal combustion engine 2. The internal combustion engine 2 may be a diesel engine or an otto 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 has 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 of the turbocharger. The compressor 6 then compresses air which, via an air filter 7, is sucked into an air duct 8. In order to supply as large an amount of air as possible to the internal combustion engine 2, the compressed air is cooled before it is led into the internal combustion engine 2. In this In this case, the compressed air is cooled in a first stage in a coolant-cooled charge air cooler 9 and in a second stage in an air-cooled charge air cooler 10 before it, via a branch 11, is led to the respective cylinders of the combustion engine 1.

The liquid-cooled charge air cooler 9 is included in a low-temperature cooling system. The low temperature cooling system comprises a line circuit 12 with a circulating coolant. The line circuit 12 comprises a cooler element 13 where the circulating coolant is adapted to be cooled by air. The line circuit 12 also comprises an electrically driven circulation pump 14 which is adapted to circulate the coolant in the line circuit 12. The circulation pump 14 is drivable at a variable speed. The circulation pump 14 is controlled by a control unit 15. The control unit 15 controls the circulation pump 14 by means of information regarding parameters such as the load of the internal combustion engine and information from a sensor 16 which senses the ambient temperature. The air-cooled charge air cooler 10 is arranged at a front part A of the vehicle. The charge air cooler 10 and the radiator element 13 are mounted here in a substantially common plane which is substantially perpendicular to the flow direction of the air in the first area A. The air is led here parallel through the charge air cooler 10 and the radiator element 13. This ensures that both temperature.

The combustion engine 1 is cooled in a conventional manner by means of a cooling system comprising a line circuit 18 with a coolant circulating by means of a coolant pump 19. The circuit also comprises a thermostat 20 and a cooler 21, which is mounted in area A of the vehicle which is permeated by ambient air. The cooler 21 is arranged downstream of the air-cooled charge air cooler 10 and the cooler element 13 with respect to the intended flow direction of the air in the area A. A radiator fl spike 22 is adapted to suck an air stream through the area A. The air flow here first passes through the air-cooled charge air cooler 10 and the radiator element 13 before it reaches the radiator 21. The air as when the radiator 21 thus has an elevated temperature in relation to the ambient temperature. However, this is usually not a problem as the temperature of the coolant in the cooling system of the internal combustion engine should normally have a temperature in the range 80-100 ° C.

Fig. 2 shows the second charge air cooler 10 and the radiator element 13 at the front part of the vehicle in the plane B-B. The air-cooled charge air cooler 10 comprises an inlet tank 10a, which is adapted to receive air compressed by the compressor 6. The air is received via an opening 10a1 in the inlet tank 10a. The air-cooled charge air cooler 10 includes a cooling portion 10b where the compressed air is adapted to be cooled by air flowing through the cooling portion 10b. The air-cooled charge air cooler 10 includes an outlet tank 10c adapted to receive the cooled air from the cooling portion 10b. The cooled air leaving the air-cooled charge air cooler 10 is led out through an opening 10c1 in the outlet tank 10c and is passed on in the air line 8 to the combustion engine 2. The intermediate portion 10b is arranged in a space 17 between the inlet tank 10a and the outlet tank 10c. However, the intermediate portion 10b does not occupy the entire space 17 between the inlet tank 10a and the outlet tank 10c. In a upper portion 17a of the space 17, the cooler element 13 has been arranged. The cooler element 13 comprises an inlet tank 13a where the coolant is received. The coolant is then passed into a cooler portion 13b which includes tubular portions.

The coolant flowing through the tubular portions is cooled by air flowing in passages located between the tubular portions. The cooled coolant from the cooling portion 13b is received in an outlet tank 13c after which it is led to the coolant-cooled charge air cooler 9 where it cools the compressed air in a first step. The air-cooled charge air cooler 10 and the radiator element 13 consist essentially of flat radiator packages, each of which has a main distribution in one plane. The cooler 21 is seen in Fig. 2 behind the air-cooled charge air cooler 10 and the cooler element 13.

During operation of the diesel engine 1, the exhaust gases in the exhaust line 4 drive turbine 5 before being led out to an environment. The turbine 5 thereby provides a driving force, which drives the compressor 6. The compressor 6 thereby compresses the air which, via the air filter 7, is led into the air line 8. In order to e.g. To reduce emissions, the air fed to internal combustion engines is compressed to a relatively high pressure, which means that the air provides a correspondingly relatively high temperature. The compressed air can have a temperature of up to about 260 ° C after compression. The compressed and heated air is led from the compressor 6 to the coolant-cooled charge air cooler 9 where it is cooled in a first stage by the coolant which is circulated in the low-temperature cooling system. Since the circulating coolant in the low temperature cooling system is cooled by air with ambient temperature in the cooler element 13, the coolant can have a relatively low temperature when it reaches the first charge air cooler 9 and thus provide a very good cooling of the air in the first stage.

The control unit 15 receives substantially continuously information regarding the load of the internal combustion engine 2. With information about the load of the combustion engine, the control unit 15 can estimate the compression that the air receives in the compressor 6 and thus the air temperature when it reaches the coolant-cooled charge air cooler 9. The control unit also receives information from the sensor 16 regarding the ambient air temperature. The temperature and speed of the cooling air stream are related to how efficiently the coolant is cooled in the cooler element 13 and how the compressed air is cooled in the air-cooled charge air cooler 10. With the help of this information the control unit 15 can control the circulation pump 14 so that a coolant is obtained in the low temperature cooling system. at which a desired cooling of the charge air in the coolant-cooled charge air cooler 9 is obtained. After cooling in the first charge air cooler 9, the air is led to the second charge air cooler 10 where it is cooled by air at ambient temperature. The air here can be cooled to a temperature close to the ambient temperature. The cooled compressed air is then led through the air line 8 to the internal combustion engine 2. Alternatively, the cooled compressed air can be mixed with recirculating exhaust gases before the mixture is led to the internal combustion engine 2.

The compressed air inevitably receives a certain pressure drop when it is led in the air line 8 from the compressor 6 to the combustion engine 2. In particular, the air can obtain a relatively large pressure drop when it is cooled in an air-cooled charge air cooler. The pressure drop in a corresponding coolant-cooled charge air cooler 9 is significantly lower. In this case, by cooling the compressed air in a first stage in a coolant-cooled charge air cooler 9, the air obtains a lower temperature and a higher density when it reaches the air-cooled charge air cooler 10. Since the compressed air is only cooled in a second stage in the air-cooled the charge air cooler 10, it can be made smaller. The reduced radiator portion 10b of the air-cooled charge air cooler 10 exposes a space 17a between the inlet tank 10a and the outlet tank 10c of the charge air cooler 10. In this exposed space 17a which is thus flowed by a cooling air stream during operation of the combustion engine 2, the radiator tank 13 is thus arranged. 10a and the outlet tank 10c of the charge air cooler 10 are sized so that their upper end portions are at least level with the highest portion of the radiator 21 behind.

A further advantage of cooling the compressed air in a first step before it is cooled in the air-cooled charge air cooler is that the tubular portions in the cooling portion 10b can be made of aluminum, which is a material which has very good heat transfer properties. However, the strength of aluminum decreases at high temperatures. Therefore, for reasons of strength, it is not possible to use conventional charge air coolers with tubular elements of aluminum to conduct compressed air with temperatures of the order of 260 °. Thanks to the cooling of the compressed air in the first stage, the second radiator section can be made of aluminum to cool the compressed air in the second stage.

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

Claims (10)

10 15 20 25 30 35 Patent claim An arrangement for cooling compressed air led to an internal combustion engine (2) in a vehicle (1), the arrangement comprising an air-cooled charge cooler (10) comprising an inlet tank (10a) adapted to receive compressed air from a compressor , a cooling portion (10b) where the compressed air is adapted to be cooled and an outlet tank (10c) adapted to receive the compressed air after cooling in the cooling portion (10b), the cooling portion (10b) being arranged in a space (17). ) located between the inlet tank (10a) and the outlet tank (10c) and wherein the space (17) is arranged in an area (A) of the vehicle (1) which is traversed by a cooling air stream during operation of the internal combustion engine (2), characterized in that the arrangement comprises a cooling system comprising a line circuit (12) with a circulating coolant, a charge air cooler (9) where the circulating coolant is adapted to cool the compressed air in a first step before it is cooled in the air. cooled charge air cooler (10) in a second stage and a cooler element (13) where the circulating coolant is adapted to be cooled by air, the cooler element (13) being arranged in a part of the space (17a) between the inlet tank (10a) and the outlet tank. (10c) not occupied by the cooling portion (10b). Arrangement according to claim 1, characterized in that the cooler element (13) is arranged in a position above the cooling portion (10b) in said space (17a) between the inlet tank (10a) and the outlet tank (10c). Arrangement according to claim 1 or 2, characterized in that the cooler element (13) comprises an inlet tank (13a) which is adapted to receive coolant to be cooled, a cooling portion (13b) where the coolant is adapted to be cooled by air which flows through the space (17a) and an outlet tank (13c) adapted to receive the cooled coolant. Arrangement according to any one of the preceding claims, characterized in that said cooling system comprises a pump (14) which is adapted to circulate the coolant in the cooling system at a variable speed. Arrangement according to claim 4, characterized in that the arrangement comprises a control unit (15) which is adapted to control the speed of the pump (14) during operation of the internal combustion engine (2). 10 15 20 10 Arrangement according to claim 5, characterized in that the control unit (15) is adapted to control the pump (14) by means of information regarding at least one parameter which is related to the temperature which the compressed air obtains after it has cooled in the first (9). ) the charge air cooler or in the other (10) charge air cooler. Arrangement according to claim 6, characterized in that the control unit (15) is adapted to receive information regarding a parameter which is related to the load of the internal combustion engine (2). Arrangement according to claim 6 or 7, characterized in that the control unit (15) is adapted to receive information from a sensor (16) which senses or estimates the temperature of the cooling air stream flowing through the space (17) between the inlet tank (17). 10a) and the outlet tank (10c). Arrangement according to claim 8, characterized in that the air-cooled charge air cooler (10) and the radiator element (13) are arranged in an area (A) of the vehicle where they are permeated by air with ambient temperature during operation of the internal combustion engine (2). Arrangement according to one of the preceding claims, characterized in that the air-cooled charge air cooler (10) and the radiator element (13) are arranged at a front portion of the vehicle (1) in a position in front of the radiator (21) of the vehicle (1) for cooling the coolant in a cooling system that cools the internal combustion engine (2).