CN111188705A - Supercharged internal combustion engine with exhaust gas recirculation and method for producing a compressor housing of such an internal combustion engine - Google Patents

Supercharged internal combustion engine with exhaust gas recirculation and method for producing a compressor housing of such an internal combustion engine Download PDF

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Publication number
CN111188705A
CN111188705A CN201911042108.6A CN201911042108A CN111188705A CN 111188705 A CN111188705 A CN 111188705A CN 201911042108 A CN201911042108 A CN 201911042108A CN 111188705 A CN111188705 A CN 111188705A
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CN
China
Prior art keywords
compressor
internal combustion
combustion engine
exhaust gas
housing
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Pending
Application number
CN201911042108.6A
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Chinese (zh)
Inventor
A·库斯克
C·W·维吉尔德
F·A·萨默候夫
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Ford Global Technologies LLC
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Ford Global Technologies LLC
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Publication of CN111188705A publication Critical patent/CN111188705A/en
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D29/00—Details, component parts, or accessories
    • F04D29/40—Casings; Connections of working fluid
    • F04D29/42—Casings; Connections of working fluid for radial or helico-centrifugal pumps
    • F04D29/4206—Casings; Connections of working fluid for radial or helico-centrifugal pumps especially adapted for elastic fluid pumps
    • F04D29/4213—Casings; Connections of working fluid for radial or helico-centrifugal pumps especially adapted for elastic fluid pumps suction ports
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
    • F01D17/00—Regulating or controlling by varying flow
    • F01D17/10—Final actuators
    • F01D17/12—Final actuators arranged in stator parts
    • F01D17/14—Final actuators arranged in stator parts varying effective cross-sectional area of nozzles or guide conduits
    • F01D17/141—Final actuators arranged in stator parts varying effective cross-sectional area of nozzles or guide conduits by means of shiftable members or valves obturating part of the flow path
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
    • F01D17/00—Regulating or controlling by varying flow
    • F01D17/10—Final actuators
    • F01D17/12—Final actuators arranged in stator parts
    • F01D17/14—Final actuators arranged in stator parts varying effective cross-sectional area of nozzles or guide conduits
    • F01D17/146—Final actuators arranged in stator parts varying effective cross-sectional area of nozzles or guide conduits by throttling the volute inlet of radial machines or engines
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B39/00—Component parts, details, or accessories relating to, driven charging or scavenging pumps, not provided for in groups F02B33/00 - F02B37/00
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M26/00—Engine-pertinent apparatus for adding exhaust gases to combustion-air, main fuel or fuel-air mixture, e.g. by exhaust gas recirculation [EGR] systems
    • F02M26/02—EGR systems specially adapted for supercharged engines
    • F02M26/09—Constructional details, e.g. structural combinations of EGR systems and supercharger systems; Arrangement of the EGR and supercharger systems with respect to the engine
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M26/00—Engine-pertinent apparatus for adding exhaust gases to combustion-air, main fuel or fuel-air mixture, e.g. by exhaust gas recirculation [EGR] systems
    • F02M26/13—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories
    • F02M26/17—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories in relation to the intake system
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M26/00—Engine-pertinent apparatus for adding exhaust gases to combustion-air, main fuel or fuel-air mixture, e.g. by exhaust gas recirculation [EGR] systems
    • F02M26/13—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories
    • F02M26/17—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories in relation to the intake system
    • F02M26/21—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories in relation to the intake system with EGR valves located at or near the connection to the intake system
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M26/00—Engine-pertinent apparatus for adding exhaust gases to combustion-air, main fuel or fuel-air mixture, e.g. by exhaust gas recirculation [EGR] systems
    • F02M26/13—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories
    • F02M26/35—Arrangement or layout of EGR passages, e.g. in relation to specific engine parts or for incorporation of accessories with means for cleaning or treating the recirculated gases, e.g. catalysts, condensate traps, particle filters or heaters
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M26/00—Engine-pertinent apparatus for adding exhaust gases to combustion-air, main fuel or fuel-air mixture, e.g. by exhaust gas recirculation [EGR] systems
    • F02M26/51—EGR valves combined with other devices, e.g. with intake valves or compressors
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M26/00—Engine-pertinent apparatus for adding exhaust gases to combustion-air, main fuel or fuel-air mixture, e.g. by exhaust gas recirculation [EGR] systems
    • F02M26/52—Systems for actuating EGR valves
    • F02M26/64—Systems for actuating EGR valves the EGR valve being operated together with an intake air throttle
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B37/00—Engines characterised by provision of pumps driven at least for part of the time by exhaust
    • F02B37/12—Control of the pumps
    • F02B37/24—Control of the pumps by using pumps or turbines with adjustable guide vanes
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
    • F05D2220/00—Application
    • F05D2220/40—Application in turbochargers

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Supercharger (AREA)
  • Exhaust-Gas Circulating Devices (AREA)

Abstract

The invention relates to a supercharged internal combustion engine, comprising: an air intake system (1); an exhaust emission system; at least one compressor (2) arranged in the air intake system (1); an exhaust gas recirculation system comprising a recirculation line which branches off from the exhaust gas discharge system and opens into the intake system (1) upstream of the at least one compressor (2) to form a node (5); and a valve unit (3) arranged at the node (5), comprising a flap (4), which flap (4) is pivotable about a rotational axis extending transversely to the shaft of the at least one compressor (2), blocks the air intake system (1) and opens the recirculation line in a first end position, and covers the recirculation line and opens the air intake system (1) in a second end position. An internal combustion engine is provided in which condensate formation in a free charge air stream upstream of at least one compressor wheel is reduced or impeded. This is achieved by an internal combustion engine, wherein the compressor housing (2a) and at least a part of the valve housing (3a) are formed integrally, such that the compressor housing (2a) and at least a part of the valve housing (3a) form a one-piece component.

Description

Supercharged internal combustion engine with exhaust gas recirculation and method for producing a compressor housing of such an internal combustion engine
Technical Field
The invention relates to a supercharged internal combustion engine, comprising:
-an air intake system for supplying a flow of pressurized air;
-an exhaust gas discharge system for discharging exhaust gas;
-at least one compressor arranged in the air intake system and equipped with at least one impeller mounted on a rotatable shaft in a compressor housing;
-an exhaust gas recirculation system comprising a recirculation line branching off from the exhaust gas discharge system and opening into the intake system upstream of the at least one impeller to form a node; and
a valve unit arranged at the node in the intake system and comprising a valve housing and a flap (flap) arranged in the valve housing, wherein the flap is pivotable about a rotational axis extending transversely to the shaft of the at least one compressor, such that the flap blocks the intake system with a front side and opens the recirculation line in a first end position and covers the recirculation line with a rear side on the exhaust side and opens the intake system in a second end position.
The invention also relates to a method for producing a compressor housing of such an internal combustion engine.
Internal combustion engines of this type are used, for example, as motor vehicle drives. In the context of the present invention, the term "internal combustion engine" covers diesel engines and gasoline engines, but also hybrid internal combustion engines (i.e. internal combustion engines operating by a hybrid combustion process) and hybrid drive arrangements which comprise not only an internal combustion engine but also at least one other torque source for driving the motor vehicle, for example an electric motor, which is connected or connectable to the internal combustion engine for driving purposes and which provides power alternatively or in addition to the internal combustion engine.
Background
In recent years, development has focused on supercharged engines, where the economic importance of these engines for the automobile industry is increasing.
Charging/supercharging is primarily a method of improving performance in which the air required for the combustion process of the engine is compressed so that a greater amount of air can be supplied to each cylinder per working cycle. In this way, the fuel mass and thus the mean pressure can be increased.
Charging is a suitable method for increasing the power of an internal combustion engine with a constant capacity or reducing the capacity for the same power. In any case, the inflation leads to an increased power-to-volume ratio and a more favorable power-to-mass ratio. If the capacity is reduced, the load set is moved to a higher load at which the fuel consumption (specific fuel consumption) is lower.
In the development of internal combustion engines, the charge supports the constant goal of minimizing fuel consumption, i.e. improving the efficiency of the internal combustion engine.
In combination with a suitable transmission ratio, this may also allow a so-called downshifting, wherein also a lower specific fuel consumption is achieved. The rundown takes advantage of the fact that the specific fuel consumption is generally lower at low rotational speeds, in particular at higher loads.
Usually, for charging, an exhaust gas turbocharger is used, in which a compressor and a turbine are arranged on the same shaft. The hot exhaust stream is supplied to a turbine and expands, releasing energy to the turbine, thereby rotating the shaft. The energy released from the exhaust gas flow to the turbine and ultimately to the shaft is used to drive a compressor also disposed on the shaft. The compressor delivers and compresses charge air supplied to it, thereby charging the cylinders. Advantageously, a charge cooler is provided in the intake system downstream of the compressor, which cools the compressed charge air before it enters the at least one cylinder. The cooler reduces the temperature of the charge air and thus increases the density of the charge air, so it also contributes to a better filling of the cylinder, i.e. a greater air mass. Compression is achieved by cooling.
An advantage of an exhaust-gas turbocharger compared to a supercharger (which may be driven by an auxiliary drive) is that the exhaust-gas turbocharger utilizes the exhaust-gas energy of the hot exhaust gas, while the supercharger absorbs the energy required for its drive directly or indirectly from the internal combustion engine and thus adversely affects (i.e. reduces) the efficiency, at least since the drive energy does not come from the energy recovery system.
If the supercharger is not one that can be driven by an electric motor (i.e., electrically driven), a mechanical or kinematic connection is typically required to transfer power between the supercharger and the internal combustion engine, which also affects packaging in the engine compartment.
The advantage of a supercharger over an exhaust-gas turbocharger is that the supercharger always generates the required boost pressure and is able to provide the required boost pressure independently of the operating state of the internal combustion engine. This applies in particular to superchargers which can be electrically driven by means of an electric motor and are therefore independent of the crankshaft speed.
According to the prior art, it is difficult to increase the power by means of exhaust gas turbocharging in all rotational speed ranges. A greater torque drop is observed below a certain rotational speed. It is understood that this torque drop is also understandable if it is recalled that the charge pressure ratio is dependent on the turbine pressure ratio or turbine power. If the engine speed decreases, this results in a smaller exhaust gas mass flow, which results in a lower turbine pressure ratio or a lower turbine power. Thus, the charging pressure ratio also decreases toward lower rotational speeds. This corresponds to a torque drop.
Disclosure of Invention
The internal combustion engine which is the subject of the invention has a compressor for charging purposes, wherein in the context of the invention the term "compressor" means in principle both the compressors of a supercharger and an exhaust-gas turbocharger which can be driven by means of an auxiliary drive.
Advantages can also be achieved not only in terms of fuel consumption (i.e. efficiency of the internal combustion engine) but also in terms of exhaust emissions if the charge is designed appropriately. Thus, by means of a suitable charge, for example in a diesel engine, nitrogen oxide emissions can be reduced without loss of efficiency. At the same time, hydrocarbon emissions can be favorably influenced. As fuel consumption decreases, the carbon dioxide emissions directly related to fuel consumption in any case decrease.
Further measures need to be taken in order to comply with future limits of pollutant emissions and aeration. The development work has focused on reducing nitrogen oxide emissions, which is highly relevant, particularly for diesel engines. Since the formation of nitrogen oxides requires not only an excess of air but also high temperatures, one idea for reducing nitrogen oxide emissions is to develop a combustion process with a lower combustion temperature.
Exhaust Gas Recirculation (EGR), i.e. the recirculation of combustion gases from the exhaust side to the inlet side, is a suitable method, wherein the nitrogen oxide emissions may be significantly reduced as the exhaust gas recirculation rate increases. Exhaust gas recirculation rate xEGRIs herein determined as xEGR＝mEGR/(mEGR+mAir) Wherein m isEGRRepresents the mass of the recirculated exhaust gas, and mAirIndicating the supply of air. The oxygen provided via exhaust gas recirculation must also be taken into account.
To achieve a significant reduction in nitrogen oxide emissions, a high exhaust gas recirculation rate is required, which may be xEGROn the order of 60% to 70%.
The internal combustion engine charged by means of the compressor according to the invention is also equipped with at least one exhaust gas recirculation system, wherein a recirculation line branching off from the exhaust gas discharge system opens into the intake system upstream of the compressor to form a node, as in the case of a low-pressure EGR system, wherein the exhaust gas which has flowed through a turbine arranged in the exhaust gas discharge system is recirculated to the inlet side. To this end, the low-pressure EGR system comprises a recirculation line which branches off from the exhaust-gas discharge system downstream of the turbine and opens into the intake system preferably upstream of the compressor.
The internal combustion engine as subject of the invention further comprises a valve unit arranged in the intake system at the node. The valve unit includes a valve housing and a flapper disposed in the valve housing.
The damper serves for regulating the amount of fresh air supplied via the intake system and, in cooperation with further components, for metering the amount of exhaust gas recirculated through the exhaust gas recirculation system; it can be pivoted about an axis extending transversely to the compressor shaft, such that in a first end position the front side of the flap blocks the air intake system and simultaneously opens the recirculation line, and in a second end position the rear side of the flap covers the recirculation line and simultaneously opens the air intake system. In this case, blocking and covering does not necessarily mean closing or complete blocking and covering.
The axis extending across the compressor shaft and about which the baffle may pivot need not be a physical shaft. Instead, the axis may be a virtual axis, the position of which may also have a slight play (play) with respect to the valve housing or the rest of the intake system, wherein the mounting or fixing takes place in a different manner.
When the exhaust gas recirculation system is in operation, problems may arise if exhaust gas is introduced into the intake system upstream of the compressor. I.e. a condensate may be formed. There are several situations.
First, when the recirculated hot exhaust gas encounters and mixes with cold fresh air, condensate may form. The exhaust gas cools and the temperature of the fresh air increases. The temperature of the mixture of fresh air and recirculated exhaust gas (i.e., the charge air temperature) is lower than the exhaust gas temperature of the recirculated exhaust gas. During cooling of the exhaust gas, if the temperature falls below the dew point of the components of the gaseous charge air stream, liquid (in particular water) that was still previously present in gaseous form in the exhaust gas may condense out.
Condensate forms in the free charge air stream, wherein contaminants in the charge air generally constitute a starting point for the formation of condensate droplets. In this case, it must be noted that the exhaust gas periodically flows around or flushes the baffle when the exhaust gas recirculation system is in operation, and the exhaust gas and fresh air are already mixed directly in the valve housing when the exhaust gas is introduced at the node.
Secondly, when the hot exhaust gas or charge air hits the inner walls of the intake system or the valve housing or baffles, condensation may form, because the wall temperature is typically below the dew point of the relevant gas components.
As the recirculation rate increases, the problem of condensation formation worsens, since as the amount of recirculated exhaust gas increases, the proportion of the individual exhaust gas components in the charge air necessarily increases, in particular the proportion of water contained in the exhaust gas. Therefore, according to the prior art, the amount of exhaust gas recirculated by means of low-pressure EGR is generally limited in order to suppress or reduce condensation. The high exhaust gas recirculation rate required firstly for the necessary limitation of low-pressure EGR and secondly for a significant reduction in nitrogen oxide emissions leads to different objectives in calibrating the recirculated exhaust gas quantity. Legal requirements for reducing nitrogen oxide emissions indicate a high relevance of this problem in practice.
Condensation and condensate droplets are undesirable and result in increased noise emissions in the intake system and, in some cases, damage to the blades of at least one compressor wheel. Damage to the blades of the compressor wheel is associated with a reduction in compressor efficiency.
For this reason, the valve unit or node is preferably placed as close as possible to the compressor, i.e. in the vicinity of the at least one impeller, so as to provide the shortest possible distance Δ. Arranging the valve unit close to the compressor shortens the travel distance of the hot recirculated exhaust gas from the point of introduction into the intake system at the node to the at least one impeller, so that the time during which condensate droplets may form in the free charge air stream is reduced. This inhibits the formation of condensate droplets.
The above concept is regularly implemented in terms of design, since the valve housing (also belonging to the intake system) is placed, i.e. mounted, between the upstream intake system and the downstream compressor housing.
Under the above circumstances, it is an object of the present invention to provide a supercharged internal combustion engine according to a preferred embodiment of the present invention, in which the formation of condensate in the free charge air flow upstream of the at least one compressor wheel is reduced or hindered.
Another part of the object is to indicate a method for manufacturing a compressor housing of such an internal combustion engine.
The first object is achieved by a supercharged internal combustion engine having:
-an air intake system for supplying a flow of pressurized air,
-an exhaust gas discharge system for discharging exhaust gas,
at least one compressor arranged in the air intake system and equipped with at least one impeller mounted on a rotatable shaft in a compressor housing,
-an exhaust gas recirculation system comprising a recirculation line branching off from the exhaust gas discharge system and opening into the intake system upstream of the at least one impeller to form a node, and
a valve unit arranged at the node in the intake system and comprising a valve housing and a flap arranged in the valve housing, wherein the flap is pivotable about a rotational axis extending transversely to the shaft of the at least one compressor, such that the flap blocks the intake system with a front side and opens the recirculation line in a first end position and covers the recirculation line with a rear side on the exhaust side and opens the intake system in a second end position,
it is characterized in that
The compressor housing and at least a part of the valve housing are integrally formed such that the compressor housing and at least a part of the valve housing form a one-piece component.
According to the invention, the valve housing is at least partially integrated in the compressor housing, so that at least a part of the valve housing forms an integral part with the compressor housing.
This design concept or feature of the internal combustion engine according to the invention brings about a number of advantages.
First, the valve unit or node is placed very close to the compressor, i.e. near at least one impeller, so that the shortest possible distance Δ is formed. Thus, the travel distance of the hot recirculated exhaust gas from the point of introduction into the air intake system at the node point until the at least one impeller is shortened as much as possible. Shorter travel distances may be used to form condensed droplets and the time that condensed droplets may form in the free pressurized air stream is shorter. The design concept of the internal combustion engine according to the invention thus prevents the formation of condensate droplets.
Secondly, the compressed heated charge air and thus also the heated compressor housing can be used as a heater for heating the valve housing, by means of which the temperature of the inner wall of the valve housing is increased, in particular due to heat conduction. By means of the heating, the wall temperature of the inner wall of the valve housing can be raised above the dew point temperature of the gaseous components of the exhaust gas or charge air. Condensation on the inner wall of the compressor housing can thereby be avoided or reduced.
Since the formation of condensation is already suppressed in the valve housing and the inlet region of the compressor, the noise emission due to the condensate droplets is also not increased. The risk of damaging the impeller blades of at least one compressor is eliminated. The efficiency of the compressor is improved or kept unaffected by exhaust gas recirculation.
It is not necessary to limit the amount of recirculated exhaust gas, and therefore a high recirculation rate can be achieved to significantly reduce nitrogen oxide emissions.
Another advantageous effect is that the number of components is reduced due to the overall design, not only reducing weight, but also simplifying installation and reducing costs. There is no need to provide a seal between the valve housing and the compressor housing to form a leak-free connection.
The first object on which the invention is based is achieved with an internal combustion engine according to the invention in that a supercharged internal combustion engine is provided in which the formation of condensate in the free charge air flow upstream of at least one compressor wheel is reduced or counteracted.
In the case of exhaust gas recirculation, the exhaust gas which has preferably undergone exhaust gas aftertreatment (in particular the exhaust gas in the particulate filter) is preferably conducted through a compressor. This prevents deposits in the compressor from altering the geometry of the compressor, in particular the geometry of the flow cross-section, and reducing the efficiency of the compressor.
Further advantageous embodiments of a supercharged internal combustion engine are explained in connection with alternative embodiments.
An embodiment of the supercharged internal combustion engine in which the axis of rotation is arranged close to the edge, i.e. close to the edge portion of the baffle, is advantageous. In this embodiment, the flapper is mounted to the side in the manner of a door and may pivot at one of its edges. This distinguishes the baffle according to the invention from a centrally mounted shut-off element or baffle, such as for example a butterfly valve.
An embodiment of the supercharged internal combustion engine in which the axis of rotation is arranged close to the wall, i.e. close to a wall portion of the valve housing, is advantageous. The valve housing usually has the function of a frame relative to the flap, i.e. it constitutes the frame of the flap. In this regard, embodiments in which the axis of rotation is disposed proximate to an edge portion of the baffle plate are also typically embodiments in which the axis of rotation is disposed proximate to an edge portion of the valve housing. The main advantage of both embodiments is that in the second end position the baffle is positioned close to the wall, creating a completely free passage for fresh air. Thereby minimizing the risk of the baffle undesirably forming a flow obstruction.
An embodiment of the supercharged internal combustion engine in which the baffle forms part of the wall of the valve housing in the second end position is advantageous. In the second end position, the baffle abuts almost seamlessly against the inner wall of the valve housing, so that no flow obstacle for the fresh air flow is formed, thereby improving the load variation on the inlet side.
It is advantageous that the baffle fits a shape with minimal clearance to the walls surrounding the baffle.
An embodiment of the supercharged internal combustion engine is advantageous in which at least one compressor is a radial compressor (radial compressor), so that the outflow (outflow) of compressed charge air from the compressor takes place substantially radially.
In contrast to turbines, compressors are defined by their outflow. A radial compressor is thus a compressor in which the outflow from the blades takes place substantially radially. In the context of the present invention, the phrase "substantially radially" means that the velocity component in the radial direction is greater than the axial velocity component. The compressor housing may be configured as a scroll or turbine case (work) housing.
Radial compressors having a spiral peripheral outlet region are particularly well suited for heating valve housings using compressed heated charge air and a heated compressor housing.
If the at least one compressor is a compressor of an exhaust-gas turbocharger, the turbine of the exhaust-gas turbocharger is preferably configured as a radial turbine. This embodiment allows for a dense packaging of the exhaust gas turbocharger and thus of the charging system as a whole.
Nevertheless, an embodiment may also be advantageous in which at least one compressor is an axial compressor. The outflow from the impeller blades of an axial compressor occurs substantially axially.
An embodiment of the supercharged internal combustion engine is advantageous in which the at least one compressor has an inlet region which extends coaxially with the shaft of the compressor and is configured such that the inflow of charge air into the compressor takes place substantially axially.
In the case of an axial inflow to the compressor, the charge air flow in the intake system upstream of the at least one compressor wheel generally does not need to be deflected or changed in direction, whereby unnecessary pressure losses in the charge air flow due to flow deflection are avoided and the pressure of the charge air at the compressor inlet increases. The absence of a change in direction also reduces contact of the exhaust gas or charge air with the inner walls of the air intake system or the compressor housing, thereby reducing heat transfer and condensate formation.
An embodiment of the supercharged internal combustion engine in which at least one exhaust-gas turbocharger is provided, which comprises a turbine arranged in the exhaust-gas discharge system and a compressor arranged in the intake system, is advantageous. With regard to the above-described embodiments, reference is made to the statements that have been made in connection with exhaust gas turbocharging, in particular the advantages outlined.
In this case, an embodiment of the supercharged internal combustion engine is advantageous in which the at least one compressor is a compressor of the at least one exhaust-gas turbocharger.
An embodiment of the supercharged internal combustion engine in which the recirculation line branches off from the exhaust-gas exhaust system downstream of the turbine of the at least one exhaust-gas turbocharger, according to a low-pressure EGR system, is advantageous when at least one exhaust-gas turbocharger is used.
In contrast to a high-pressure EGR system, which introduces exhaust gas extracted from the exhaust gas discharge system upstream of the turbine into the intake system, preferably downstream of the compressor, in a low-pressure EGR system, exhaust gas that has passed through the turbine is supplied to the inlet side. For this purpose, the low-pressure EGR system has a recirculation line which branches off from the exhaust-gas discharge system downstream of the turbine and opens into the intake system upstream of the compressor.
The main advantage of low-pressure EGR compared to high-pressure EGR is that the exhaust-gas flow introduced into the turbine in the case of exhaust-gas recirculation is not reduced by the amount of recirculated exhaust gas. The entire exhaust flow is always available at the turbine to produce a sufficiently high charge pressure.
The exhaust gas which is recirculated to the inlet side by means of the low-pressure EGR system and is cooled in some cases is mixed with fresh air upstream of the compressor. The mixture of fresh air and recirculated exhaust gas produced in this way forms charge air or combustion air, which is supplied to the compressor and compressed.
An embodiment of the supercharged internal combustion engine in which the shut-off element is arranged in the exhaust gas exhaust system downstream of the turbine of the at least one exhaust-gas turbocharger is advantageous when at least one exhaust-gas turbocharger is used, wherein the recirculation line branches off from the exhaust gas exhaust system between the turbine and the shut-off element.
The blocking element may be used to increase exhaust pressure upstream of the exhaust emission system, thereby increasing or contributing to a pressure differential between the exhaust emission system and the intake system. This provides the advantage of a high recirculation rate, particularly where a greater pressure differential is required.
An embodiment of the supercharged internal combustion engine in which the shut-off element is arranged in the intake system upstream of the node point is advantageous. The stop element on the inlet side serves to reduce the pressure in the intake system and can therefore contribute to an increase in the pressure difference between the exhaust gas discharge system and the intake system.
An embodiment of the supercharged internal combustion engine is advantageous in which, for adjusting the amount of recirculated exhaust gas, the valve is provided in the valve housing and comprises a valve body which is arranged on the rear side of the flap and is connected and thereby mechanically coupled to the flap, wherein the valve body blocks the recirculation line at the second end position of the flap.
Pivoting of the flapper causes spatial adjustment or movement of the valve. The flap thus serves as an actuating device for the valve. All the variants of the above-described embodiment have the feature that the flap is used only for regulating the amount of air supplied via the air intake system and not for metering the amount of recirculated exhaust gas. The latter is achieved by a valve which is placed in the recirculation line or on an opening of the recirculation line and which serves as an EGR valve.
An embodiment of a supercharged internal combustion engine is advantageous in which the node point is arranged at a distance Δ from the at least one compressor wheel, wherein Δ ≦ 1.5D for the distance ΔVAnd D isVIndicating the diameter of at least one compressor wheel.
Disposing the node close to the compressor shortens the travel distance of the hot recirculated exhaust gas from the introduction point into the air intake system until the at least one compressor wheel, thereby reducing the time to form condensate droplets in the free charge air stream.
In this case, an embodiment of a supercharged internal combustion engine is advantageous in which Δ ≦ 1.0D for the distance ΔVPreferably, Δ ≦ 0.75 Dv.
In this case, an embodiment of the supercharged internal combustion engine is advantageous in which Δ ≦ 45mm, preferably Δ ≦ 40mm or Δ ≦ 35mm for the distance Δ.
In order to improve the torque characteristics of a supercharged internal combustion engine, it may be advantageous to provide two or more compressors or exhaust turbochargers, for example several exhaust turbochargers, connected in series. By connecting two exhaust-gas turbochargers in series, one of which serves as a high-pressure stage and the other as a low-pressure stage, the compressor map can advantageously be expanded towards smaller compressor flows and towards larger compressor flows.
Furthermore, the torque characteristics can be improved by several turbochargers arranged in parallel, i.e. by several turbines with smaller turbine cross sections arranged in parallel, wherein the turbines are set successively in operation as the exhaust gas quantity increases.
An embodiment of the supercharged internal combustion engine in which the compressor housing and the valve housing are formed integrally is advantageous in that the compressor housing and the entire valve housing form a one-piece component.
A second partial object on which the invention is based, namely to propose a method for producing a compressor housing of an internal combustion engine of the type described above, is achieved by a method which is characterized in that the compressor housing and at least a part of the valve housing are formed integrally.
The statements made above in relation to the internal combustion engine according to the invention also apply to the method according to the invention, so reference is made in this connection generally to the statements made above in relation to a supercharged internal combustion engine.
An embodiment of the method is advantageous in which the compressor housing and at least a part of the valve housing are formed integrally during the casting process.
An embodiment of the method is also advantageous in which an additive manufacturing method is used in order to build up the compressor housing and at least a part of the valve housing as layers and thus configure them integrally.
The following embodiment of the method is advantageous, wherein 3D printing is used as the additive manufacturing method.
An embodiment of the method in which the compressor housing is made of aluminum is advantageous.
Drawings
The invention will now be explained in more detail with reference to an exemplary embodiment shown in fig. 1. The figure shows that:
fig. 1 shows schematically and in a perspective view a compressor arranged in an intake system with a valve unit in a first embodiment of an internal combustion engine, with a baffle in a second end position and facing a compressor wheel.
Detailed Description
Fig. 1 shows schematically and in a perspective view a compressor 2 arranged in an intake system 1 with a valve unit 3 in a first embodiment of an internal combustion engine, with a baffle 4 in a second end position and facing a compressor wheel in the direction of a charge air flow.
The internal combustion engine has an intake system 1 for supplying cylinders with charge air, and an exhaust-gas turbocharger for charging the cylinders is provided; the turbocharger comprises a turbine (not shown) arranged in the exhaust gas discharge system and a compressor 2 arranged in the intake system 1. The compressor 2 is in this case a radial compressor 2' with a spiral peripheral outlet region, which has an impeller rotatably mounted in a compressor housing 2a, wherein the shaft of the impeller projects from the plane of the drawing in fig. 1. The compressor 2 has an inlet region which extends coaxially with the shaft and is configured such that the intake system 1 has no change of direction upstream of the compressor 2, and the inflow of fresh air or charge air to the compressor 2 and its impeller takes place substantially axially.
The internal combustion engine is also equipped with an exhaust gas recirculation system comprising a recirculation line which opens into the intake system 1 upstream of the compressor 2 to form a node 5.
A valve unit 3 is arranged at the node 5, which valve unit 3 comprises a valve housing 3a and a flap 4 in the valve housing 3 a.
In this case, the valve housing 3a is integrated in the compressor housing 2a, i.e. the valve housing 3a and the compressor housing 2a form a one-piece component. In this way, the node 5 can be arranged very close to the compressor 2, i.e. near the impeller, to form the shortest possible distance Δ.
The flap 4 is pivotable about a rotational axis extending transversely to the shaft. Fig. 1 shows the flap 4 in a second end position, in which the rear side of the flap 4 covers the recirculation line of the exhaust gas recirculation system, while the air inlet system 1 is open. In the second end position, the baffle 4 almost seamlessly abuts against the inner wall of the valve housing 3a and therefore does not constitute a flow obstacle for the fresh air flow. Advantageously, the front side 4a of the flap 4 forms a form fit with the surrounding inner wall of the valve housing 3a which is as free of steps as possible.
List of reference numerals
1 air intake system
2 compressor
2' radial compressor
2a compressor housing
3-valve unit
3a valve housing
4 baffle
Front side of 4a baffle
5 node
Delta distance from node to impeller
EGR exhaust gas recirculation
DvDiameter of at least one impeller
mEGRMass of recirculated exhaust gas
mFreshairQuality of fresh air supplied
xEGRExhaust gas recirculation rate

Claims (18)

1. A supercharged internal combustion engine having:
an air intake system (1) for supplying a flow of pressurised air,
an exhaust gas discharge system for discharging exhaust gas,
at least one compressor (2) arranged in the air intake system (1) and equipped with at least one impeller mounted on a rotatable shaft in a compressor housing (2a),
an exhaust gas recirculation system comprising a recirculation line which branches off from the exhaust gas discharge system and opens into the intake system (1) upstream of the at least one impeller to form a node (5), and
a valve unit (3) arranged at the node (5) in the intake system (1) and comprising a valve housing (3a) and a flap (4) arranged in the valve housing (3a), wherein the flap (4) is pivotable about a rotational axis extending transversely to the shaft of the at least one compressor (2) such that the flap (4) blocks the intake system (1) with a front side (4a) and opens the recirculation line at a first end position and covers the recirculation line with a rear side on the exhaust side and opens the intake system (1) at a second end position,
the method is characterized in that:
the compressor housing (2a) and at least a part of the valve housing (3a) are formed integrally, such that the compressor housing (2a) and at least a part of the valve housing (3a) form a one-piece component.
2. A supercharged internal combustion engine according to claim 1, characterized in that the axis of rotation is arranged close to an edge portion of the baffle (4).
3. A charged internal combustion engine according to claim 1 or 2, characterized in that the axis of rotation is arranged close to a wall of the valve housing (3 a).
4. A charged internal combustion engine according to claim 3, characterized in that the baffle (4) forms part of the wall of the valve housing (3a) in the second end position.
5. A supercharged internal combustion engine according to any one of the preceding claims, characterized in that said at least one compressor (2) is a radial compressor (2') so that the outflow of compressed charge air from the compressor (2) takes place substantially radially.
6. A charged internal combustion engine according to any one of the preceding claims, characterized in that the at least one compressor (2) has an inlet region which extends coaxially to the shaft of the compressor (2) and is configured such that the inflow of charged air to the compressor (2) takes place substantially axially.
7. A charged internal combustion engine according to any one of the preceding claims, characterized in that at least one exhaust-gas turbocharger is provided, which comprises a turbine arranged in the exhaust-gas discharge system and a compressor arranged in the intake system (1).
8. A charged internal combustion engine according to claim 7, characterized in that the at least one compressor (2) is the compressor of the at least one exhaust-gas turbocharger.
9. A charged internal combustion engine according to claim 8, characterized in that a shut-off element is arranged in the exhaust gas exhaust system downstream of the turbine of the at least one exhaust-gas turbocharger, wherein the recirculation line branches off from the exhaust gas exhaust system between the turbine and the shut-off element.
10. A charged internal combustion engine according to any one of the foregoing claims, characterised in that a shut-off element is arranged in the intake system (1) upstream of the node (5).
11. A charged internal combustion engine according to any one of the foregoing claims, characterised in that, for adjusting the recirculated amount of exhaust gas, a valve is provided in the valve housing (3a) and comprises a valve body which is arranged on the rear side of the flap (4) and is connected and thereby mechanically coupled to the flap (4), wherein the valve body blocks the recirculation line at the second end position of the flap (4).
12. A charged internal combustion engine according to any one of the preceding claims, characterized in that the node (5) is arranged at a distance Δ from the at least one compressor wheel, wherein Δ ≦ 1.5D for the distance ΔVAnd D isVIndicating a diameter of the at least one compressor wheel.
13. A supercharged internal combustion engine according to claim 12, characterized in that for distance Δ ≦ 1.0DV。
14. According toA supercharged internal combustion engine according to claim 12, characterized in that for distance Δ ≦ 0.75DV。
15. A charged internal combustion engine according to any one of the preceding claims, characterized in that the compressor housing (2a) and the valve housing (3a) are integrated such that the compressor housing (2a) and the entire valve housing (3a) form a one-piece component.
16. Method for producing a supercharged internal combustion engine according to any one of the preceding claims, characterized in that the compressor housing (2a) and at least a part of the valve housing (3a) are formed integrally.
17. A method according to claim 16, characterized in that the compressor housing (2a) and at least a part of the valve housing (3a) are integrated in a casting process.
18. A method according to claim 16, characterised by using an additive manufacturing method in order to build the compressor housing (2a) and at least a part of the valve housing (3a) as layers and thus to form them integrally.
CN201911042108.6A 2018-11-14 2019-10-30 Supercharged internal combustion engine with exhaust gas recirculation and method for producing a compressor housing of such an internal combustion engine Pending CN111188705A (en)

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