DE102015226104A1 - Air system for an internal combustion engine with an improved cooling power electronics of an electric auxiliary compressor assembly through the intake passage - Google Patents

Abstract

An air system (1) for an internal combustion engine with an auxiliary compressor arrangement, wherein the air system (1) • an intake passage (2) adapted to supply air to a combustion chamber (3), • an auxiliary compressor (4) adapted thereto Aspirating air from the intake duct (2) and re-emitting compressed air into a pressure duct (9), • an electric motor (5) driving the auxiliary compressor (4), • power electronics (6) adapted to the electric motor (5) to control, • a support plate (7) on which the power electronics (6) is arranged comprises, wherein the carrier plate (7) the power electronics (6) to the intake passage (2) thermally connects, wherein the intake passage (2 ) serves as a heat sink and the intake passage (2) has a connection region (21) in which the thermal connection of the support plate (7) with the intake passage (2) is formed, wherein in the connection region (21) of the intake passage (2) at least one R ippe (30) in the interior of the intake passage (2) is formed.

Description

State of the art

The invention relates to an air system for an internal combustion engine according to the preamble of claim 1.

In today's internal combustion engines or internal combustion engines, the performance is improved by the use of air compressors such as turbochargers or compressors. The compressor increases the boost pressure of the air in the combustion chamber, so that it is possible to inject more fuel for combustion, which improves the overall performance of the internal combustion engine or the internal combustion engine.

The turbocharger is typically driven by the exhaust gas flow of the internal combustion engine or the internal combustion engine and uses the principle of radial compression to build up the air pressure in the intake duct leading to the combustion chamber and in the combustion chamber. The turbocharger rotates at up to 200,000 rpm. The performance of the turbocharger depends on the engine speed.

Compressors, such as rotary piston loader, spiral loader, vane loader or piston charge pump, are usually driven by the internal combustion engine via chain, belt or gear transmission. However, this increases the fuel consumption of the internal combustion engine.

In general, in a relatively large air volume of about 4 to 10 liters, between the compressor and the combustion chamber, a higher air pressure must be built, which is regardless of the particular compressor used relatively long pressure build-up times, in turn, as a long reaction time of the internal combustion engine or of the internal combustion engine. In the automotive industry in particular, efforts have been made in the recent past to improve the pressure build-up and thus also the reaction time by means of electrically operated auxiliary compressors (additional electric compressor). The auxiliary electric compressors are operated for a relatively short time, particularly in the range of low engine speeds, and assist the primary normal compressor in building up the air pressure. The electric auxiliary compressor can be operated independently of the speed of the engine.

As with the turbocharger, radial compressors are often used as electrical supplementary compressor. Due to the principle, the centrifugal compressor must be operated at 80-100% of its maximum possible speed so that the desired air pressure is built up. The operation of an electrically driven centrifugal compressor typically requires a power of 3-5kW.

Alternatively, loaders that work with the principle of displacement (displacement loader), e.g. a spiral loader, to be used as an additional compressor. These have the advantage that the flow rate of the supercharger depends on the speed of the supercharger, i. The torque of the supercharger determines the built-up pressure. If at a load point in the operation of the internal combustion engine only a low flow rate of air is needed, e.g. only 1/3 of the maximum air flow, the supercharger must be operated with only 1/3 of its maximum torque. Thus, the supercharger is ready for use faster and the reaction time and the energy to be used are lower at a lower air flow requirement than in radial compressors. Furthermore, you only need a power of about 2.4 kW for the operation of an electrically driven supercharger.

The introduction of new components such as an additional compressor in addition to a primary compressor, such as turbocharger or compressor, in the air system of an internal combustion engine or internal combustion engine give new tasks or challenges and issues that need to be solved.

Advantage of the invention / disclosure of the invention

Typically, the centrifugal compressor is powered by an electric motor operating at a voltage of 48V or a 12V with capacitor system, power 3-5kW. The positive displacement charger can be operated with a power of about 2.4 kW, which can be provided by a 12V system without a capacitor. In both implementations, high currents flow in the power electronics. Even with good efficiencies, a loss of power in the form of heat is not completely excluded. Thus, for the power electronics of the electric motor that drives the auxiliary compressor, effective cooling is needed.

Accordingly, it is an object of the present invention to provide an improved cooling arrangement for power electronics of an electric auxiliary compressor for an internal combustion engine.

This object is achieved according to the invention in the air system of the type mentioned by the characterizing feature of claim 1.

According to the invention, it is provided that the air system has an intake passage which is adapted to supply air to a combustion chamber, an auxiliary compressor which is adapted to suck in air from the intake passage and compressed air into one Output pressure channel again, an electric motor that drives the auxiliary compressor, power electronics, which is adapted to control the electric motor, a support plate on which the power electronics is arranged, wherein the carrier plate thermally connects the power electronics with the intake passage, wherein the intake duct serves as a heat sink and the intake duct has a connection region in which the thermal connection of the carrier plate to the intake duct is formed, wherein at least one rib is formed in the interior of the intake duct in the connection region of the intake duct. This results in the advantages that a locally close and very effective heat sink for the power electronics is available with the intake passage. The intake passage is very well suited as a heat sink, since fresh air flows through the intake passage during operation of the internal combustion engine, which has the temperature of the ambient air of about -30 ° C to about + 40 ° C. Furthermore, the fresh air flows at a relatively high speed through the intake passage and accordingly offers a high heat capacity. The power electronics typically have a maximum operating temperature of about + 120 ° C, so the temperature difference between the maximum allowable operating temperature of the power electronics and the air flowing in the intake air is at least 80 ° C. The greater the temperature difference, the more effective is the cooling capacity of the heat sink, here the intake duct. The better the cooling of the power electronics works, the smaller the power electronics can be configured and the cheaper the power electronics component becomes. By forming at least one rib in the connection region of the intake duct, the surface of the connection region which is in contact with the cooling air flowing through the connection region is increased and thus the effective cooling capacity of the connection region as heat sink for the power electronics is improved. The ribs and the outer surfaces of the connection area are thermally connected to each other.

Further advantageous developments are the subject of the dependent claims.

Advantageously, the at least one rib is arranged longitudinal to the flow direction of the air, i. the larger side surface of the rib is aligned parallel to the flow direction of the air, this ensures that the ribs are well flowed around by the air without increasing the flow resistance for the air.

In an advantageous further development, a plurality of ribs are arranged parallel to one another, whereby the contact area between connection region and cooling air flow is further increased.

In a further advantageous development, a plurality of ribs are arranged in a cross shape or at an angle to one another, whereby the contact area between connection region and cooling air flow is further increased.

Advantageously, the one rib or the plurality of ribs are fastened in the connection region of the intake pipe by caulking or welding or soldering. It is important that a sufficiently good thermal connection between the ribs and the outer surface of the connection area is ensured.

Alternatively, the at least one rib or the plurality of ribs may be integrally formed with the bonding portion of the suction pipe, thereby ensuring good thermal bonding.

It has proved to be advantageous for a good cooling performance that the connection region and / or the support plate and / or the at least one rib of material having a thermal conductivity of at least 30 W / (m · K), in particular at least 60 W / (m · K) ), exists or exists. For example, a metal, in particular aluminum or an aluminum alloy or copper or a copper alloy, is used as material for the connection region and / or for the carrier plate and / or for the at least one rib.

In order to provide a sufficiently large contact area between the carrier plate, which provides the thermal connection to the power electronics, and the connection area and to ensure good thermal contact between the two components, it has been found to be advantageous if the carrier plate at least along half the circumference of the connection region of the suction channel abuts against the outer surface of the connection region. It is particularly advantageous if, in addition, the carrier plate and the connection region of the intake channel are materially connected to one another, in particular soldered or welded together.

For a sufficiently good cooling performance, the connection region should advantageously have at least a length L of 50 mm and in particular a maximum length of 200 mm. It has additionally proven to be advantageous that the at least one rib or the plurality of ribs are at least half as long as the length L of the connection region, preferably at least 75% of the length of the connection region.

In addition or as an alternative to the above-mentioned embodiments, it can be provided that the power electronics are arranged in a housing, wherein the carrier plate is one side of the housing. As a result, a particularly effective thermal connection and thus also cooling of the power electronics is provided via the carrier plate.

drawing

1 shows an example of an air system with an additional compressor arrangement

2 shows the auxiliary compressor arrangement in detail

3 shows an embodiment of the arrangement of the ribs in the connection area

4 shows a second embodiment of the arrangement of the ribs in the connection area

5 shows a further embodiment of the arrangement of the ribs in the connection area

Description of the embodiment

1 shows a schematic, highly simplified representation of the air system and the exhaust system of an internal combustion engine 1 , When air system is via an intake 2 Fresh air from the environment of the internal combustion engine 1 sucked and to the combustion chamber 3 directed. The exhaust system is via an exhaust duct 30 after the combustion process, the exhaust gas from the combustion chamber 3 discharged again. The exhaust system may include various components for analysis and aftertreatment of the exhaust gas at or in the exhaust passage 30 have, for example, a catalyst or a lambda probe or a NOx sensor.

The intake channel 2 can be divided into several sections or physically consists of several components and sections. For example, various portions may be distinguished due to components disposed in the sections or disposed between two sections, such as an air filter 32 , a turbocharger 31 , an air cooler, a bypass flap 8th or an additional compressor 4 , or due to the material or function of a portion of the intake duct 2 such as bypass or air collector 10 or connection area 21 or pressure channel 9 ,

The primary compressor is a turbocharger in this example 31 passing through the exhaust gas in the exhaust duct 30 is driven and air into the intake 2 conveyed, creating a certain air pressure in the intake passage 2 is built up. That through the primary compressor and the combustion chamber 3 limited volume of the intake duct 2 typically has a size of 4-10 liters depending on the exact location of the primary compressor in the intake port 2 and depending on the dimensions of the internal combustion engine 1 , By increasing the air pressure, the compressed air heats up. In order to cool the warm and compressed air again, for example, a charge air cooler may be arranged in the air flow direction downstream of the primary compressor. The cooling of the compressed air prevents the warm, compressed air from introducing additional heat into the combustion chamber 3 and thus adversely affects the combustion process.

Not shown in 1 are for example intake valve and exhaust valve on the combustion chamber 3 separating the combustion chamber from the intake duct 2 and from the exhaust duct 30 disconnect, or possible air cooler in the intake duct 2 , Furthermore, the fuel system is not shown, via which the fuel from a reservoir via injection valves in the intake passage 2 and / or directly into the combustion chamber 3 is injected and possible distribution lines, also called rails, for the distribution of air and / or fuel to multiple combustion chambers 3 , Also missing in the presentation of 1 the electronic system that controls and regulates the injectors, the intake and exhaust valves, as well as the throttle or bypass valves 8th and the monitoring and evaluation of the values recorded by the various sensors for controlling the various components of the internal combustion engine 1 ,

In 2 the detail of the air system with the additional compressor arrangement is shown in more detail. The arrows symbolize, as in the other figures, the flow direction of the air and the exhaust gas.

In air flow direction in front of the combustion chamber 3 the auxiliary compressor arrangement is arranged. The auxiliary compressor arrangement comprises an additional compressor 4 , an electric drive 5 , such as an electric motor, the additional compressor 4 drives, as well as power electronics 6 that the electric drive 5 from the power grid of the internal combustion engine 1 supplied with the necessary electrical power. Thus the electrical connection between electric drive 5 and power electronics 6 is as short as possible, is the power electronics 6 preferably directly to the electric drive 5 arranged. As a common contact surface is for example a carrier plate 7 at the power electronics 6 is arranged. For example, the carrier plate 7 in turn on a housing of the electric drive 5 be attached. Additionally or alternatively, the connection between the power electronics 6 and the electric drive 5 also be formed over the electrical lines.

The additional compressor 4 is with the intake duct 2 about as an air collector 10 designated portion of the intake passage 2 fluidly connected. About the air collector 10 can in addition to the auxiliary compressor 4 another section of the intake duct 2 in which a bypass flap 8th is arranged with the intake passage 2 be fluidly connected. The bypass flap portion of the intake passage 2 serves to air at the additional compressor 4 over, without additional compression in the direction of the combustion chamber 3 to lead. The itself the additional compressor 4 and the bypass flap portion of the intake passage 2 in the air flow direction subsequent portion of the intake passage 2 is also called a pressure channel 9 designated.

The additional compressor 4 is for example a centrifugal compressor or supercharger, such as a spiral loader.

The carrier plate 7 connects the power electronics 6 with the intake channel 2 , The section of the intake duct 2 the one with the carrier plate 7 is connected as a connection area 21 designated. The connection area 21 becomes like the intake duct 2 flows through the sucked air and serves as a heat sink for cooling the power electronics 5 , The carrier plate 7 takes that from the power electronics 6 generated heat and passes the heat to the heat sink on. The carrier plate 7 provides a thermal connection between the power electronics 6 and the intake channel 2 or the connection area 21 ago.

The intake channel 2 and / or the connection area 21 and / or the ribs ( 30 ) consist of a material with a good thermal conductivity of at least 30 W / (m · K). An optimal thermal connection can be achieved when the carrier plate 7 also consists of a material with a good thermal conductivity of at least 30 W / (m · K).

Advantageously, the carrier plate 7 with the intake channel 2 or the connection area 21 cohesively connected. The common contact surface between the carrier plate 7 and the connection area 21 should be as big as possible. An effective heat transfer is already achieved when the carrier plate 7 at least 50% of the circumference of the connection area 21 on its outer circumference 40 is applied.

The connection area 21 should have a length L of at least 50 mm so that the connection region has a sufficiently large surface for the thermal contact with the air flowing through it.

The connection area 21 can as an intermediate piece of the intake duct 2 be trained or the air collector 10 also serves as a connection area 21 ,

3 shows an example of the arrangement of ribs in the connection area 21 in the section transversely to the flow direction of the air at the level of about half the length of the connection region ( 3A ) and in section along the flow direction of the air ( 3B ).

In this exemplary embodiment, two ribs in the connection region are cross-shaped in relation to one another in the connection region 21 arranged. Ribs 30 extend only over part of the length L of the connection area 21 , Advantageously, the ribs have 30 at least one length as the width B of the carrier plate 7 , Ribs 30 are in the connection area in this example 21 caulked. Basically, the ribs can 30 also be soldered or welded. Alternative can be the ribs 30 also in one piece with the bonding area 21 be educated.

The embodiment according to 4 differs from the embodiment according to 3 only by the length of the ribs 30 , Ribs 30 extend here over the entire length L of the connection area 21 , Basically, the ribs can 30 in the connection area 21 caulked, soldered or welded. Alternative can be the ribs 30 also in one piece with the bonding area 21 be educated.

In 5 are different arrangements of ribs 30 in the connection area 21 shown. Ribs 30 can be like in 3 only over a partial length of the connection area 21 extend or over the entire length L of the connection area 21 extend. Basically, the ribs can 30 in the connection area 21 caulked, soldered or welded. Alternative can be the ribs 30 also in one piece with the bonding area 21 be educated.

In 5A) are several ribs arranged parallel to each other 30a . 30b . 30c . 30d . 30e in the connection area 21 shown. In 5B) are the ribs 30a . 30b . 30c arranged as a double cross. In 5C) form the ribs 30a . 30b . 30c . 30d together a diamond-shaped pattern. In 5D) are the ribs 30a . 30b . 30c arranged in a zigzag pattern. In the zigzag arrangement, the ends of the ribs must 30a . 30b . 30c not necessarily touching.

The number of ribs used in the embodiments 30 is only an example. The embodiments may also each with more or less than illustrated ribs 30 will be realized.

Claims (13)

Air system ( 1 ) for an internal combustion engine with an additional compressor arrangement, wherein the air system ( 1 ) • an intake duct ( 2 ), which is adapted to a combustion chamber ( 3 ) To supply air, • an auxiliary compressor ( 4 ), which is adapted to air from the intake duct ( 2 ) and suck compressed air into a pressure channel ( 9 ), • an electric motor ( 5 ), the additional compressor ( 4 ), • power electronics ( 6 ), which is adapted to the electric motor ( 5 ), • a carrier plate ( 7 ), at which the power electronics ( 6 ), characterized in that the carrier plate ( 7 ) the power electronics ( 6 ) with the intake duct ( 2 ) thermally connects, wherein the intake duct ( 2 ) serves as a heat sink and the intake duct ( 2 ) a connection area ( 21 ), in which the thermal connection of the carrier plate ( 7 ) with the intake duct ( 2 ) is formed, wherein in the connection area ( 21 ) of the intake duct ( 2 ) at least one rib ( 30 ) inside the intake duct ( 2 ) is trained. Air system ( 1 ) according to claim 1, characterized in that the at least one rib ( 30 ) is formed longitudinally to the flow direction of the air. Air system ( 1 ) according to claim 2, characterized in that a plurality of ribs ( 30a , b, c, d, e) are arranged parallel to each other. Air system ( 1 ) according to claim 2, characterized in that a plurality of ribs ( 30a , b, c) are arranged in a cross shape or at an angle to each other. Air system ( 1 ) according to claims 1 to 4, characterized in that the at least one rib ( 30 ) or the plurality of ribs in the connection area ( 21 ) of the intake pipe by caulking or welding or soldering are fastened. Air system ( 1 ) according to claims 1 to 4, characterized in that the at least one rib ( 30 ) or the plurality of ribs integral with the connection area ( 21 ) of the intake pipe are formed. Air system ( 1 ) according to one of the preceding claims, characterized in that the connection area ( 21 ) and / or the carrier plate ( 7 ) and / or the at least one rib ( 30 ) of material having a thermal conductivity of at least 30 W / (m · K), in particular at least 60 W / (m · K). Air system ( 1 ) according to claim 7, characterized in that the material of the connection area ( 21 ) and / or the material of the carrier plate ( 7 ) and / or the material of the at least one rib ( 30 ) is a metal, in particular aluminum or an aluminum alloy or copper or a copper alloy. Air system ( 1 ) according to one of the preceding claims, characterized in that the carrier plate ( 7 ) at least along half the circumference of the connection region ( 21 ) of the intake duct on the outer surface ( 40 ) of the connection area Air system ( 1 ) according to one of the preceding claims, characterized in that the carrier plate ( 7 ) and the connection area ( 21 ) of the intake duct are materially interconnected, in particular soldered or welded together. Air system ( 1 ) according to one of the preceding claims, characterized in that the connection area ( 21 ) at least one length (L) of 50 mm and in particular has a maximum length of 200mm. Air system ( 1 ) according to one of the preceding claims, characterized in that the at least one rib ( 30 ) or the plurality of ribs at least half as long as the length (L) of the connection region ( 21 ), preferably at least 75% of the length of the attachment region. Air system ( 1 ) according to one of the preceding claims, characterized in that the power electronics ( 6 ) is arranged in a housing, wherein the carrier plate ( 7 ) is one side of the housing.

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