DE102005032002A1 - Supercharger for internal combustion (IC) engine used in automobile, has turbine wheel having low and high pressure stages each consisting of turbine blades - Google Patents

Abstract

A supercharger turbine (5) has a turbine wheel (20) having low and high pressure stages (21,23). Each of the stages includes turbine blades. The blades in the low pressure stage rotate opposite to one exhaust gas flow stream (30), while the blades in the high pressure stage rotate opposite two exhaust gas flow streams (31,32). The flow streams run through different sized passage areas. In addition, the blades are formed of ceramic or a titanium or aluminum alloy. An independent claim is also included for an IC engine with a supercharger.

Description

The The invention relates to an exhaust gas turbocharger for an internal combustion engine according to the preamble of Claim 1 and an internal combustion engine according to the preamble of the claim 12th

turbocharger are both foreign-charged as well as self-igniting Internal combustion engines to increase used the cylinder charge. The increase of the cylinder charge leads next an increase in output to an increase in the combustion air ratio and thus with auto-igniting Internal combustion engines to reduce soot formation in the lower and medium load and speed range and, depending on the combustion temperature, reduce nitrogen oxide emissions.

The Reduction of pollutant emissions through exhaust gas recirculation both externally ignited as well as self-igniting Internal combustion engines, today state of the art. The higher the Exhaust gas recirculation rate is, the lower you can be the pollutant emissions. The exhaust gas recirculation brings at the same Aufladegrad a performance loss of the internal combustion engine with it. To prevent this loss of power, or in addition to the exhaust gas recirculation To increase performance, the degree of supercharging or the boost pressure must be raised. The increase of the supercharging degree respectively the boost pressure is achieved today by a multi-stage charge. This multi-stage charge leads to a high space requirement, since a housing in a given Engine compartment of the at least two exhaust gas turbochargers are realized got to.

From the generic European patent specification EP 1 092 085 B1 is known an exhaust gas turbocharger with a two-stage compressor. A compressor wheel of the compressor is designed such that it has, in addition to the usual, first Verdichterradbeschaufelung at its Radrücken another, second Verdichterradbeschaufelung. The air drawn by the compressor flows through the first Verdichtradbeschaufelung, a so-called. Low pressure stage, and enters at the exit from the blading in a spiral channel, which is connected to an inlet channel of the second Verdichterradbeschaufelung. From there, the air continues to flow into the second compressor wheel blading, the so-called high-pressure stage, and is compressed at the latest in this pressure stage.

The Compression of the intake air in the low-pressure stage depends on the speed of the exhaust gas turbocharger. In the low speed range of Exhaust gas turbocharger flows the sucked air through the Verdichterradbeschaufelung without that it is compressed or without the boost pressure significantly increases. A compression of the intake air already in the first Verdichterradbeschaufelung, namely the low-pressure stage occurs only from a medium to high speed of the exhaust gas turbocharger one.

The Object of the present invention is, in addition to the increase the degree of supercharging of the internal combustion engine and the associated possible Increase in exhaust gas recirculation quantity To provide a compact, space-reduced exhaust gas turbocharger.

These Task is solved by an exhaust gas turbocharger with the features of claim 1 as well by an internal combustion engine with the features of claim 12. The dependent claims give expedient further education at.

Of the has exhaust gas turbocharger according to the invention a two-stage turbine on. With the two-stage turbine can be an increase the Aufladegrades the internal combustion engine can be achieved. On a Hub of the turbine are a first turbine wheel blading one first pressure stage and a second turbine wheel blading a second pressure level arranged. This space-saving, compact Arrangement of the two pressure levels is achieved in that the second Turbinenradbeschaufelung the second pressure stage at Radrücken the first turbine wheel blading of the first pressure stage and both Turbine wheel blading is arranged on the common hub.

In an embodiment according to claim 2, the first turbine wheel blading on a first flood and the second turbine wheel blading over one the second and third tide can be applied. The separation of the floods offers the possibility of one of the Turbinenradbeschaufelungen or bypass one of the pressure levels.

In a further embodiment according to claim 3, the second and formed the third tide with different sized flow cross sections. Due to the different sizes Flow areas are different pressures in the floods before, so that the pressure difference in the flow cross sections to the flow the exhaust gas from one flood to the other and thus to increase the exhaust gas recirculation amount is usable.

In a further embodiment according to claim 4, the pressure to increase the efficiency of the turbine at different operating points stages suitably of different sizes. The first pressure stage is a low pressure stage and the second pressure stage is a high pressure stage. A relaxation of the exhaust gas in the low-pressure stage offers the possibility for large amounts of exhaust gas, as they occur for example in the upper load range of the engine, to achieve a favorable efficiency of the turbine. In the high pressure stage, even with a small amount of exhaust gas, as occurs, for example, in the low load range of the internal combustion engine, a favorable efficiency of the turbine can be achieved.

In A further embodiment according to claim 5, the pressure levels expediently via a flow line connected with each other.

In A further embodiment according to claim 6 is the compressor to increase the charging of the engine formed in two stages.

In a further embodiment according to claim 7, a compressor wheel the compressor, a first Verdichterradbeschaufelung and a second Verdichtradbeschaufelung on. The second Verdichterradbeschaufelung is space-saving on a Radrücken provided the first Verdichterradbeschaufelung the compressor wheel.

In A further embodiment according to claim 8, the turbine and the compressor expediently via a Shaft rotatably connected with each other.

In a further embodiment according to claim 9 is at least the from a bearing of the exhaust gas turbocharger farthest turbine wheel blading made of a material with low density. This low Density of the material favors the dynamics and the response of the turbocharger.

In a further embodiment according to claim 10, the material low density preferably a ceramic material or a material that is ceramic-like Features.

In a further embodiment according to claim 11, the material low density, preferably an alloy of titanium and aluminum.

The according to the invention internal combustion engine Claim 12 with an exhaust gas turbocharger according to claims 1 to 11 has for power control the exhaust gas turbocharger on a control device which the exhaust gas duct to first, second and third flood controls. The control device serves to regulate the power of the turbine.

In A further embodiment according to claim 13 is the control device also for metering the exhaust gas recirculation quantity intended. The control device should be set so that the Pressure in connection with an intake tract of the internal combustion engine standing second tide rises. This can be done, for example, over the Shut down the third flood can be achieved. Thus, the pressure gradient, which between the second tide and the intake tract is increased, whereby the exhaust gas recirculation amount can be increased.

In A further embodiment according to claim 14 is the control device preferably a rotary valve.

In A further embodiment according to claim 15 is the third flood a control to open and closing assigned to the third flood, so by closing the third tide, for example, exhaust from the third tide to the second Tide can be blown over.

In a further embodiment according to claim 16 is the control expediently formed as a flow-controlling valve.

In a further embodiment according to claim 17 is the control expediently designed as an adjustable throttle body, for example as a flap.

In A further embodiment according to claim 18 is for power limitation the turbine in engine braking the first tide from the controller open.

In A further embodiment according to claim 19 is to increase performance the turbine in engine braking the first tide from the controller closed.

Further Advantages and expedient designs The invention are the other claims, the description of the figures and to take the drawing. Show it:

1 a schematic representation of an internal combustion engine with an exhaust gas turbocharger according to the invention and

2 a section through a turbine of the exhaust gas turbocharger according to the invention, with high pressure stage and low pressure stage or with first and second Turbinenradbeschaufelung.

In the figures, all the same or equivalent components with the same reference numerals Mistake.

The in the 1 illustrated internal combustion engine 1 , which may be a gasoline engine or a diesel engine, is with an exhaust gas turbocharger according to the invention 2 fitted. The turbocharger 2 includes a two-stage turbine 5 in an exhaust system 6 and a two-stage compressor 3 in an intake tract 4 , The two-stage turbine 5 and the two-stage compressor 3 are simplified in the following only as a turbine 5 and compressors 3 designated. A turbine wheel 20 the turbine 5 is about a wave 7 non-rotatable with a compressor wheel 9 of the compressor 3 connected. The wave 7 the exhaust gas turbocharger 2 is in an in 2 Exhaust gas turbocharger housing shown in detail 36 in an in 1 shown bearings 8th stored.

The compressor 3 has a low pressure stage 10 and a high pressure stage 11 , After exiting the low pressure stage 10 the compressed intake air enters an intercooler 13 who in the low pressure stage 10 Compressed intake air cools, after which it enters the high-pressure stage 11 continues to flow. A highest temperature of the low-pressure stage 10 and the high pressure stage 11 remains over even under pressure conditions 6 bar in a range in which conventional, inexpensive aluminum alloys can be used. Other features and advantages of such a compressor 3 are the European patent specification EP 1 092 085 B1 removable and are therefore not explained in detail.

In operation of the internal combustion engine 1 becomes the turbine wheel 20 the turbine 5 from the pressurized exhaust gases of the internal combustion engine 1 driven. The rotational movement of the turbine wheel 20 will be over the shaft 7 on the compressor wheel 9 of the compressor 3 transfer. The compressor 3 aspirates intake air at ambient pressure from the atmosphere, previously in an air filter 14 upstream of the compressor 3 is filtered.

Downstream of the high pressure stage 11 of the compressor 3 is in the intake tract 4 a charge air cooler 15 provided, which cools the compressed air. Subsequently, the under boost pressure air is not shown cylinders of the internal combustion engine 1 fed.

That of the internal combustion engine 1 assigned exhaust gas line 6 has a first exhaust manifold 28 and a second exhaust manifold 29 on. The first exhaust manifold 28 has a first exhaust pipe 6a on. The second exhaust manifold 29 has a second exhaust pipe 6b on.

The internal combustion engine 1 additionally has an exhaust gas recirculation device 16 on. The exhaust gas recirculation device 16 includes an exhaust gas recirculation line 17 with a shut-off valve 18 and an exhaust gas cooler 19 , Downstream of the first exhaust manifold 28 and upstream of the turbine 5 branches the exhaust gas recirculation line 17 from the first exhaust pipe 6a from and opens downstream of the intercooler 15 in the intake tract 4 one.

The turbine 5 has a low pressure stage 21 with a first tide 30 and a high pressure stage 23 with two floods, a second flood 31 and a third flood 32 , The first exhaust pipe 6a is with the second flood 31 connected. The second exhaust pipe 6b leads to the third flood 32 , The first flood 30 is in no direct connection with one of the two exhaust manifolds 28 . 29 ,

A flow line 26 downstream of the high pressure stage 23 connects the high pressure stage 23 with the low pressure stage 21 , That in the high-pressure stage 23 relaxed exhaust gas flows over the flow line 26 from the high pressure stage 23 in the low pressure stage 21 where it is relaxed a second time. From the low pressure stage 21 the exhaust gas flows over a downstream of the turbine 5 provided exhaust aftertreatment device 27 into the atmosphere.

Downstream of the branch of the exhaust gas recirculation line 17 from the exhaust pipe 6a and upstream of the turbine 5 points the exhaust gas turbocharger 2 a control device 40 on. This control device 40 is in the in 2 Exhaust gas turbocharger housing shown in detail 36 integrated. Likewise, the control device could 40 also upstream of the exhaust gas turbocharger 2 and downstream of the exhaust gas recirculation device 16 in the exhaust system 6 between the exhaust pipes 6a and 6b be integrated. In the third flood 32 is a flow controlling control 41 intended.

All units of the internal combustion engine 1 be dependent on state and operating variables of the internal combustion engine 1 of actuating signals of a control and control unit 42 set. This concerns in particular the check valve 18 in the exhaust gas recirculation line 17 , the control device 40 and the control 41 , The control 41 is designed for example in the form of a slider or a simple flap whose opening angle via the control and regulating device 42 is adjustable.

In the 2 is a section through the turbine 5 the exhaust gas turbocharger 2 shown. The low pressure stage 21 has a first spiral channel 24 on. The high pressure stage 23 has a second spiral channel 34 and a third spiral channel 35 on. The control device 40 is with the three spiral channels 24 . 34 and 35 via the floods associated with the spiral channels 30 . 31 respectively 32 connected. The first flood 30 connects the control 40 with the ers spiral channel 24 , the second tide 31 connects the control 40 with the second spiral channel 34 and the third flood 32 connects the control 40 with the third spiral channel 35 ,

The turbine wheel 20 points to his hub 33 a first and a second Turbinenradbeschaufelung, namely the Turbinenradbeschaufelung 21a the low pressure stage 21 and the turbine wheel blading 23a the high pressure stage 23 , Would you be the hub 33 with the turbine wheel blading 21a and 23a or the low pressure stage 21 and the high pressure stage 23 at an imaginary, in 2 dashed line 50 in two independent turbine wheels 21 . 23 so it could be seen that the turbine wheel blading 21a and 23a or the pressure levels 21 and 23 at her by the line 50 recognizable Radrücken 43 and 44 on each other or on their Radrücken 43 . 44 would be interconnected.

Furthermore, the two turbine wheels could 21 . 23 or at least the turbine wheel bluffings 21a . 23a be made of different materials. For the dynamics and the response of the entire turbocharger 2 would be an embodiment of at least one of the turbine wheels 21 . 23 or the turbine wheel blading 21a . 23a advantageous, which has a low-density material. The material could be a ceramic material, eg Si ₃ N ₄ , or a ceramic-like material, a ceramic alloy or a material having the same or similar properties of the ceramic material. Likewise, the material could be an alloy of aluminum and titanium, eg, TiAl, which is about one-half the density of a standard metallic material, eg, Inco713C.

The turbine wheel 20 is made in one piece. An outer diameter d _{AH of} the turbine wheel blading 23a the high pressure stage 23 is larger than an outer diameter d _{AN of} the turbine wheel blading 21a the low pressure stage 21 , Due to the difference in diameter, the turbine wheel points 20 at the Radrücken 44 the high pressure stage 23 a paragraph 60 on, which is a flow of exhaust gas from one of the two spiral channels 34 . 35 to the spiral channel 24 or from the spiral channel 24 to the spiral channels 34 . 35 prevented.

The control device 40 represents a further flow connection of the low-pressure stage 21 with the high pressure stage 23 dar. The spiral channels 34 . 35 the high pressure stage 23 are over the floods 31 respectively 32 with the control device 40 connected, in turn, over the first tide 30 with the first spiral channel 24 the low pressure stage 21 connected is. Through this flow connection of the spiral channels 24 . 34 . 35 via the control device 40 is an overflow of the exhaust gas from one spiral channel into another possible. Depending on the position of the control device 40 For example, exhaust gas from the second spiral channel 34 via the control device 40 in the third spiral channel 35 overflow.

The control device 40 allows different connection combinations of the spiral channels 24 . 34 and 35 with each other, so that the exhaust gas depends on the position of the control device 40 can flow into the appropriate pressure level. Conveniently, the control device 40 executed in the form of a rotary valve.

In operation of the internal combustion engine 1 the exhaust gas flows over the exhaust pipe 6a and the exhaust pipe 6b in the spiral channel 34 or in the spiral channel 35 , Depending on the position of the control device 40 the exhaust gas flows either almost completely or only partially across the second and third tides 31 . 32 in the control device 40 and from there on the first tide 30 in the first spiral channel 24 the low pressure stage 21 ,

It should by appropriate circuit of the control device 40 be ensured that always a certain amount of exhaust gas through the high-pressure stage 23 flows, otherwise it will be at a complete obstruction of the high-pressure stage 23 for ventilating the high-pressure stage 23 would come.

The control device 40 includes a roller 53 in a housing 54 is rotatably mounted. The roller 55 can be brought into different positions via an adjusting device, not shown, for example, a servomotor.

The roller 53 has a cavity 55 on. At its periphery, the roller 53 a total of nine openings over which the exhaust gas from the floods 30 . 31 . 32 in the cavity 55 can flow, or via the exhaust gas from the cavity 55 into the floods 30 . 31 . 32 can flow. In the in 2 illustrated position of the control device 40 are three openings 56 . 57 and 58 the roller 55 visible, noticeable.

In the in 2 illustrated position of the control device 40 the exhaust gas flows according to the flow arrows 51 from the spiral channels 34 and 35 in the second and third flood 31 . 32 , From the second and third flood 31 . 32 the exhaust gas continues to flow over the two openings 56 . 57 in the cavity 55 the control device 40 and flows from there over the opening 58 into the flood 30 , From the flood 30 it continues to flow into the first spiral channel 24 , The low pressure stage 21 is traversed by a certain amount of exhaust gas, while the other part of the Exhaust gas quantity the high pressure stage 23 flows through.

Another position of the control device 40 gives the floods 32 and 31 free while the tide 30 closed is. Thus, the exhaust gas flows exclusively in the high-pressure stage 23 and from there via the flow line 26 further into the low pressure stage 21 , Two openings, not shown, on the circumference of the roller 55 give the two floods 31 . 32 free.

In two other positions will allow the control device 40 the floods 31 and 30 or the floods 32 and 30 releases while the tide 32 or the flood 31 closed is. The release of the floods via four more openings on the circumference of the roller 55 that with the floods 31 and 30 respectively 32 and 30 correspond.

An exact assignment of the positions of the control device 40 to operating points of the internal combustion engine 1 is dependent on the geometric configuration or shaping of the floods 30 . 31 and 32 or the spiral channels 24 . 34 and 35 as well as the regulation of the exhaust gas recirculation amount and the combustion air ratio of the internal combustion engine 1 ,

The control device 40 comes the task of power control of the turbine 5 to. Depending on the position of the control device 40 is the high pressure stage 23 From the exhaust partially or almost completely bypassed.

Another task of the control device 40 is the dosage of the exhaust gas recirculation amount. The exhaust gas recirculation quantity depends on the pressure in the exhaust gas line 6a or from the pressure gradient between the exhaust pipe 6a and the intake tract 4 , The greater this pressure drop, the more exhaust gas can be, depending on the position of the check valve 18 , in the intake tract 4 be returned. For this reason, it is important to the second tide 31 and the second spiral channel 34 with corresponding cross-sections which are smaller than a cross section of the third tide 32 and a cross section of the third spiral channel 35 , As a low-efficiency has the positioning of the smaller spiral channel 34 between the spiral channels 24 and 35 proved.

A blowdown of the exhaust gas during engine braking operation is also one of the tasks of the control device 40 , With existing control 41 closes the control 41 the third flood 32 , The control 41 is not mandatory. However, it contributes to a more controlled metering of the exhaust stream. In 2 is the control 41 in the flood 32 not shown. Another possible positioning of the control 41 would be on a flange, not shown, at a transition of the second exhaust pipe 6b in the third spiral channel 35 ,

With a power limitation of the turbine 5 in engine braking operation is the control device 40 adjusted so that the exhaust gas from both the spiral channel 34 as well as from the spiral channel 35 via the control device 40 in the spiral channel 24 can flow.

A high performance of the turbine 5 in engine braking operation is by the Umblasung of the exhaust gas from the spiral channel 35 in the smaller spiral channel 34 achievable, in which case no exhaust gas in the spiral channel 24 flows. The high Aufstauwirkung and the achievable high turbine performance is a consequence of the smaller cross-section of the second spiral channel 34 or the second flood 31 ,

In engine braking operation of the internal combustion engine 1 remains the exhaust gas recirculation valve 18 generally closed.

It should be mentioned that in the transient phases of the internal combustion engine 1 in which the exhaust gas turbocharger 2 has to be accelerated, the control device 40 held in a position in which no Umblasung the high-pressure stage 23 and no re-blowing between the second and third tides 31 . 32 can be done. This means that the control device 40 the floods 30 . 31 and 32 for the exhaust gas does not release. No exhaust gas can flow from one flood to another.

Claims (19)

Exhaust gas turbocharger for an internal combustion engine, comprising a compressor and a turbine, which has a turbine wheel with a first turbine wheel blading of a first pressure stage, characterized in that the turbine ( 5 ) is formed in two stages, wherein the turbine wheel ( 20 ) in addition to the first turbine wheel blading ( 21a ) of the first pressure stage ( 21 ) a second turbine wheel blading ( 23a ) a second pressure stage ( 23 ) having. Exhaust gas turbocharger according to claim 1, characterized in that the first turbine wheel blading ( 21a ) about a first flood ( 30 ) and the second turbine wheel blading ( 23a ) about a second and third flood ( 31 . 32 ) can be flowed on. Exhaust gas turbocharger according to claim 2, characterized in that the second and third tides ( 31 . 32 ) are formed with different flow cross sections. Exhaust gas turbocharger according to one of claims 1 to 3, characterized in that the first pressure step ( 21 ) a low pressure stage and the second pressure stage ( 23 ) is a high pressure stage. Exhaust gas turbocharger according to claim 4, characterized in that the second pressure stage ( 23 ) via a flow line ( 26 ) with the first pressure level ( 21 ) connected is. Exhaust gas turbocharger according to one of claims 1 to 5, characterized in that the compressor ( 3 ) is formed in two stages. Exhaust gas turbocharger according to claim 5, characterized in that the compressor ( 3 ) a compressor wheel ( 9 ) with a first compressor wheel blading ( 10 ) and with a second compressor wheel blading ( 11 ), wherein the second compressor wheel blading ( 11 ) on a Radrücken ( 12 ) of the compressor wheel ( 9 ) is provided. Exhaust gas turbocharger according to one of claims 1 to 7, characterized in that the turbine ( 5 ) and the compressor ( 3 ) over a wave ( 7 ) are rotatably connected with each other. Exhaust gas turbocharger according to one of claims 1 to 8, characterized in that at least that of a bearing ( 8th ) farthest turbine wheel blading ( 21a ) is made of a material which has a low density. Exhaust gas turbocharger according to claim 9, characterized in that the material of Turbinenradbeschaufelung ( 21a ; 23a ) is a ceramic material or a ceramic-like material. Exhaust gas turbocharger according to claim 9, characterized in that the material of Turbinenradbeschaufelung ( 21a ; 23a ) is an alloy of titanium and aluminum. Internal combustion engine with an exhaust gas turbocharger according to one of the preceding claims, with an intake tract and an exhaust gas line, with an exhaust gas recirculation line between the intake tract and the exhaust gas line, in which an exhaust gas recirculation device is provided, characterized in that for the power control of the exhaust gas turbocharger ( 2 ) a first, a second and a third flood ( 30 . 31 . 32 ) a control device ( 40 ) assigned. Internal combustion engine according to claim 12, characterized in that the control device ( 40 ) is provided for metering the exhaust gas recirculation amount. Internal combustion engine according to claim 12 or 13, characterized in that the control device ( 40 ) is designed as a rotary valve. Internal combustion engine according to one of claims 12 to 14, characterized in that in the engine braking operation for the Umblasung of exhaust gas of the third flood ( 32 ) a control ( 41 ) assigned. Internal combustion engine according to claim 15, characterized in that the control element ( 41 ) is designed as a flow-controlling valve. Internal combustion engine according to claim 15, characterized in that the control element ( 41 ) is designed as an adjustable flap. Internal combustion engine according to claim 12, characterized in that in the engine braking operation to limit the power of the turbine ( 5 ) the first flood ( 30 ) from the control device ( 40 ) is open. Internal combustion engine according to claim 12, characterized in that in the engine braking operation to increase the performance of the turbine ( 5 ) the first flood ( 30 ) from the control device ( 40 ) closed is.