SE538517C2 - Arrangement for cooling an electric control unit in an engine room in a vehicle with an overcharged internal combustion engine - Google Patents

Abstract

The present invention relates to an arrangement for cooling an electric control unit (16) in an engine compartment (1a) in a vehicle (1) driven by an internal combustion engine (1) located in the engine compartment (1a). The arrangement comprises an inlet line (10) which is adapted to lead lu fi through the engine compartment (1) to the internal combustion engine (1). The electrical control unit (16) is fixed to the inlet line (10) in such a way that it is heat transfer contact with the air which is led through the inlet line (10) to the internal combustion engine (1). Thus, the electric control unit (16) can obtain continuously continuous cooling in the engine compartment (1a) during operation of the internal combustion engine (1). (Fig. 2)

Description

BACKGROUND OF THE INVENTION AND PRIOR ART The present invention relates to an arrangement for cooling an electric control unit in an engine compartment of a vehicle according to the preamble of the claim.

During operation, electrical control units emit a heat output of the order of 50-150 watts. Electrical control units thus emit a relatively small heating effect and it is usually sufficient that they are cooled by ambient air. However, the electrical control units in vehicles are often located in the engine compartment of the vehicle where they are used to control various components.

The air in the vehicle's engine compartment is hot. The air is sucked into the engine compartment by means of a single cooler. The air is then sucked through one or more coolers where the air cools coolant, charge air, recirculating exhaust gases, etc. before it reaches the engine fume. As these media can have a very high temperature, the air in the engine compartment obtains a temperature which is often of the order of 80 ° C. However, the air temperature in the engine compartment can, teaching operating conditions, temporarily rise to above 10 ° C. Air with such a high temperature is very poorly suited for cooling electrical control units.

To solve this problem, it is known to provide electrical control units in engine compartments with extra heat-resistant components. Such components are expensive, which leads to the electrical control units becoming expensive. It is also known to provide electric control units in the engine compartment of vehicles with a heat exchanger at the rear where the electric control units are cooled by fuel from the vehicle's fuel system. Such a solution entails an intervention in the vehicle's fuel system and that extra fuel lines must be laid in the engine compartment. The solution also leads to an increased risk of fuel leakage in the engine compartment.

SUMMARY OF THE INVENTION The object of the present invention is to provide an arrangement which enables cooling of electrical control units in an engine compartment of a vehicle in a reliable and functional manner and at a low cost.

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. Underrunning of an internal combustion engine, air is led substantially continuously through a single inlet line to the internal combustion engine in the engine compartment. The air in the inlet line has a clearly lower temperature during normal operation than the air in the engine compartment where the control unit is located. It is thus very convenient to use the inlet hatch as a medium for cooling the electric control unit. Admittedly, the air led to the internal combustion engine provides some heating as it cools the electric control unit, but this heating is substantially negligible as an electric control unit emits a relatively small heat output. Arranging the electrical control unit on the inlet line in one way so that it is cooled by the air in the inlet line can be done fairly easily and in several different ways. Such an operation can also be performed at a low cost.

According to another embodiment of the invention, the inlet line comprises at least coolers for cooling the air before it reaches the internal combustion engine and that the electrical control unit is arranged in a position downstream of said cooler with respect to the intended flow direction of the intake air in the inlet line. When the air fed to the internal combustion engine is overcharged, it needs to be cooled in at least one charge air cooler before it is led to the internal combustion engine. The compressed air thus obtains, under essentially all operating conditions, a relatively low temperature before it is led into the internal combustion engine. In order for the electric control unit to be able to provide a cooling of the air in the inlet line, the electric control unit should be arranged in the inlet line in a position downstream of the charge air cooler where the air is coldest.

According to another embodiment of the invention, the electrical control unit is provided with a contact surface which is mounted against a correspondingly shaped contact surface of the inlet line. An electrical control unit normally has a surrounding housing that encloses and protects the electrical components of the control unit. This casing is usually made of a material with good heat-conducting properties. The inlet pipe that carries air to the internal combustion engine is also normally made of a material with good heat-conducting properties. By attaching the electric control unit to a surface of the inlet line with a corresponding shape, a relatively large heat transfer area can be created between the electric control unit and the inlet line where heat energy can be transferred from the electric control unit to the air inlet line. The electrical control unit thus provides a good cooling. The inlet line advantageously comprises a surface enlargement on the inside of the said contact surface. Such a surface enlargement may comprise heat transfer elements extending into the inlet conduit. This further improves the heat transfer between the electrical control unit and the air in the inlet line.

According to another embodiment of the invention, the electrical control unit is mounted in an opening in the inlet line and that the electrical control unit is provided with a contact surface which is in contact with the air in the inlet line. In this case, the control unit contact surface can be cooled directly by the air fl inside the inlet duct. The control unit contact surface with the air in the inlet line advantageously comprises surface enlarging elements. Thereby a large increased heat transfer surface is obtained between the control unit and the air in the inlet line, which results in a more efficient cooling of the electrical control unit. Said surface enlarging elements may consist of flat end elements which have a main stretch in the intended flow direction of the air inside the inlet duct. Thus, a good heat transfer can be obtained at the same time as the flow of air inside the inlet duct is essentially not affected.

According to an embodiment of the invention, the entire electrical control unit is arranged inside the inlet line. In this case, a very good cooling of the electrical control unit is obtained as it is substantially surrounded by the air in the inlet line. Here too, the electric control unit can be provided with heat transfer för in order to make the cooling of the electric control unit more efficient. The electrical control unit can be attached to an internal wall surface in the inlet line. Alternatively, it can be attached inside the inlet pipe with suitable fastening elements.

According to an embodiment of the invention, the electrical control unit is provided with an outer surface which is in contact with ambient air. In cases where the electrical control unit is mounted on the outside of the inlet line or when it is mounted in a single opening in the inlet line, it inevitably obtains a contact surface with ambient air. The ambient air in an engine compartment has such a high temperature during normal operation that it is not suitable for cooling the electrical control unit. The contact surface of the control unit with ambient air is therefore advantageously made considerably smaller than the heat-transferring contact surface of the control unit with the inlet line and the air inlet line. Alternatively or in combination, the electrical control unit contact surface with ambient air may be made of a material having heat insulating properties. The housing of the control unit may in this case comprise a heat-insulating material, the area being in contact with ambient air. Alternatively, a cover member of a heat insulating material may be provided on top of the housing in the area in which it is in contact with ambient air in the engine compartment. With such a heat-insulating material, the control unit is substantially prevented from being heated by ambient air in the engine compartment. BRIEF DESCRIPTION OF THE DRAWINGS In the following, preferred embodiments of the invention are described with reference to the accompanying drawings, in which: Fig. 1 shows an electrical control unit cooled by inlet air. Fig. 2 shows in more detail an electric control unit attached to an inlet line which directs air to an internal combustion engine, Fig. 3 shows a cross-sectional view of the electric control unit and the inlet line in Fig. 2, Fig. 4 Fig. 5 shows a cross-sectional view of an alternative electrical control unit and inlet line and shows a cross-sectional view of a further alternative electrical control unit and inlet line.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION FIG. 1 shows a vehicle 1 driven by an overcharged internal combustion engine 2 which is arranged in an engine compartment 1a of the vehicle. Vehicle 1 may be a heavy vehicle powered by a supercharged diesel engine. The internal combustion engine 2 is cooled in a conventional manner with a cooling system comprising a circulating coolant. The coolant is circulated in the cooling system by means of a coolant pump 3. The cooling system comprises a thermostat 4 which is adapted to direct the coolant to a cooler 5 when the coolant needs to be cooled and to the combustion engine 1 when it does not need to be cooled in the cooler 5. The cooler 5 is mounted at a front portion of the vehicle 1 The exhaust gases from the cylinder of the internal combustion engine 2 are led, via an exhaust gas collector 6, to an exhaust line 7. The exhaust gases in the exhaust line 7, which have an overpressure '15, are led to a turbine 8 of a turbocharger. The turbine 8 thereby provides a drive force fi, which is transmitted, via a connection, to a compressor 9. The compressor 9 compresses air which is led into an inlet line 10. The air provides an elevated temperature during the compression.

A first charge air cooler 11 is arranged in the inlet line 10 for cooling the compressed air in a first step. The coolant in the cooling system is led in a line 12 to the first charge air cooler and in a line 13 from the first charge air cooler 11. The coolant in the cooling system is used to cool the compressed air in the first stage of the first charge air cooler 11. The compressed air can here be cooled to one temperature in the vicinity of the coolant temperature which is usually in the range 70 -90 ° C. The compressed air is then led fi er to a second charge air cooler 14 which is arranged at a front part of the vehicle 1. The second charge air cooler 14 is arranged in front of the cooler 5 with respect to the intended flow direction of the air through the coolers 5, 14. A radiator 15 sucks ambient air through the coolers 5, 14 into the vehicle engine compartment la. The air in the engine compartment 1a is relatively hot as it has been used to cool the charge air in the second charge air cooler 14 and the coolant in the cooler 5. When the compressed air is cooled in a charge air cooler 14 arranged at a front portion of the vehicle 1, it is cooled by ambient air. It is thus possible to cool the compressed air to a temperature close to ambient temperature. By cooling the compressed air to a temperature which is in the vicinity of the ambient temperature, a substantially optimal amount of air can be led to the cylinders of the internal combustion engine 2. An electric control unit 16 is arranged in the inlet line 10 in a position in the vicinity of a branch 17 which directs the compressed air to the respective cylinders of the internal combustion engine 2.

Fig. 2 shows in more detail the electric control unit 16 which is attached to the inlet line 10 adjacent to a branch 17. Fig. 3 shows a cross-sectional view through the electric control unit 16 and the inlet line 10. The electric control unit 16 comprises an interior space with schematically shown electrical components 16a . The electrical components 16a are enclosed by a surrounding housing 16b. The housing l6b consists of a material with good heat-conducting properties. Enclosure 16 may be composed of a suitable metal material. Housing 16b has an outer surface which includes a flat contact surface 16b1 with the inlet conduit 10. The inlet pipe 10 consists of a material with good heat-conducting properties such as a metal material. The inlet line 10 has, in connection with the control unit 16, a wall portion 10a which has a substantially flat contact surface 10a1 which is in mounted contact with the flat contact surface 16b1 of the control unit. The control contact surface 16b1 and the contact surface 10a11 of the inlet conduit can be mounted together with a fastener which may be a suitable adhesive or by means of a detachable coupling mechanism. However, it is important that the contact surface 16b1 of the control unit and the contact surface 10a of the inlet line; are in good heat transfer contact with each other in an assembled condition.

The inlet conduit 10 planar wall portion 10a includes internal contact surface 10a; which is in contact with the air inside the inlet duct 10. The inner contact surface 10a; includes flat end elements 10b. The flat flange elements 10b have a main stretch in the intended flow direction of the air inside the inlet duct 10.

Thus, the flange elements 10b will substantially not prevent the leakage inside the inlet duct 10. The flange elements 10b advantageously have a corresponding distance to the electrical control unit 16 on the outside of the inlet duct 10. The additional elements 10b and the air in the inlet duct 10. An additional casing of a heat-insulating material 18 is arranged above an outer surface of casing 16b which is not in contact with the inlet duct 10. Thereby the electrical control unit 16 obtains an outer contact surface 18a of a heat-insulating material 18 air.

During operation of the internal combustion engine 2, the compressed air is cooled in a first stage in the first charge air cooler 11 by coolant and in a second stage of ambient air temperature in the second charge air cooler 14. With such cooling the compressed air can often be cooled to a temperature close to the ambient air temperature. Before the cooled compressed air reaches the branch 17, it passes past the electrical control unit 16 in the inlet line 10. The air here comes into contact with the sensing elements 10b so that they obtain a substantially equivalent temperature as the air inside the inlet line 10. Thus the wall portion 10a of contact with the inlet line the control unit 16 obtain a relatively low temperature. During operation, the electrical control unit 16 develops a heating power of 50-150 watts. The electric control unit 16 thus provides single heating. In this case, the control unit 16 is cooled by the air in the inlet line 10 via the relatively large contact surfaces 10a1, 16b1 between the electric control unit 16 and the inlet line 10. The ambient temperature in an engine compartment 1a may be of the order of 80 ° C during operation. This temperature is clearly higher than the temperature of the air in the inlet line 10 and generally higher than the temperature of the electric control unit 16 after it has been cooled by the air in the inlet line 10. The extra heat insulating housing 18 here prevents the electric control unit 16 from being heated by the hot air in the engine compartment 1a. The air in the inlet conduit 10 provides some heating as the conductor is passed past the flange elements 10b. However, this heating is relatively small as the electrical control unit 16 develops a relatively small heating effect during operation. In this case, the electric control unit 16 maintains a continuously good cooling during operation of air at a relatively low temperature. Thus, the electrical control unit 16 need not include expensive electrical components that are adapted to withstand high temperatures.

Fig. 4 shows a cross-sectional view of an alternative embodiment of the electrical control unit 16 and the inlet line 10. In this case, the inlet line 10 is provided with a single opening 10c. The opening 10c is of a size such that it closes when the electrical control unit 16 is applied to the inlet line 10. To obtain a secure and tight closure, an outer surface 16b is mounted; of the housing 16b of the electrical control unit against an internal surface 10d in the inlet line adjacent to the opening 10c by means of an adhesive such as a suitable adhesive. The housing 16b in the mounted state comprises a contact surface 16b3 which is in contact with the air which is led through the inlet duct 10. The contact surface 16b3 comprises flat end elements 16c which have a main stretch in the intended flow direction of the air inside the inlet duct 10. Thus, the air outlet 16 the bilge elements 16c may extend along substantially the entire contact surface 16b of the Control Unit; with the air in the inlet duct 10. As a result, the return elements 16c obtain a large contact surface with the air inside the inlet duct 10 which results in a good heat transfer between the flange elements 16c and the air in the inlet duct 10. The housing here has a contact surface 16b4 with ambient air in the engine compartment 1. the air in the conduit 10 cools the electrical control unit 16 via the contact surface 16b3. With such cooling, the electric control unit 16 can obtain a relatively low temperature. In this case, the electrical control unit 16 is also in heat transfer contact with the ambient air via the contact surface 16b4. The contact surface 1664 of the control unit with ambient air is considerably smaller than the contact surface 16b3 of the control unit with the air in the inlet line 10 since the contact surface 16b4 with the air in the engine compartment does not comprise end elements. The electric control unit 16 receives a cooling, via the contact surface 16b4, during times when the air in the engine compartment is colder than the electric control unit 16 and a heating during times when the air in the engine compartment is warmer than the electric control unit 16. In any case, the air in the inlet duct 10 provides a continuous cooling of the electric control unit 16 substantially regardless of the temperature of the air in the engine compartment 1a. This ensures that the control unit 16 exhibits an acceptable low temperature under all operating conditions.

Fig. 5 shows a cross-sectional view of a further alternative embodiment of the electrical control unit 16 and the inlet line 10. In this case, the entire control unit 16 is mounted inside the inlet line 10. The housing 16b of the control unit also in this case comprises a contact surface 16b; The contact surface 1663 comprises flat end elements 16c having a main stretch in the intended direction of flow of air inside the inlet 10. The housing also includes a contact surface 16b5 which is attached to an inner surface 10 of the inlet. suitable glue can be applied to the said surfaces to hold the electric control unit 16 in the intended place inside the inlet line 10. The electric control unit 16 can in this case be lowered and fastened inside the inlet line 10 before it is connected to the branch 17. Since the whole electric control unit 16 in this case is arranged inside the inlet duct, the electrical control unit 16 provides a very good cooling of the air in the inlet duct 10.

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

Claims (6)

An arrangement for cooling an electric control unit (16) in an engine compartment (1a) in a vehicle (1) driven by an internal combustion engine (1) located in the engine compartment (1a), the arrangement comprising an inlet line (10) which is adapted to direct air through the engine compartment (1) to the internal combustion engine (1), the inlet line comprising a compressor (9) which compresses the air in the inlet line (11) and a cooler (14) for pre-cooling the compressed air in the inlet line (10), the electric control ( 16) is fixed to the inlet line (10) in a manner such that it is in contact with the air passed through the inlet line (10) to the internal combustion engine (1) and the electrical control unit (16) is provided with a contact surface (16b4, 18a) as in a mounted condition is in contact with ambient air, characterized in that the radiator (14) is arranged at a front part of the vehicle where the cooling ambient air and that the electric control unit (16) is arranged in the inlet line (1 0) in a position downstream of the compressor (9) and the radiator (14) with respect to the intended flow direction of the air in the inlet line (10), and that the contact surface (1 Sa) of the electrical control unit with ambient air comprises a material having heat insulating properties. Arrangement according to claim 1, characterized in that the electrical control unit (16) is provided with a contact surface (16b1) which is mounted in contact with a correspondingly shaped contact surface (10a1) of the inlet line (10). Arrangement according to claim 2, characterized in that the inlet conduit (10) comprises a surface enlargement (10b) on the inside of said contact surface (10a1). Arrangement according to claim 1, characterized in that the electrical control unit (16) is mounted in an opening (10c) in the inlet line (10) and that the electrical control unit (16) is provided with a contact surface (16b3) which is in contact with the air. inside the inlet line (10). Arrangement according to claim 4, characterized in that the electrical control unit contact surface (16b3) with the air in the inlet line comprises a surface enlarging element (16c). Arrangement according to claim 5, characterized in that said surface enlarging elements are platform fls (16c) which have a main stretch in the intended flow direction of the air inside the inlet duct (10).