DE102006014934A1 - Internal combustion engine e.g. diesel engine, has air flow adjusting device implemented as axial valve, which is arranged in flow path of air flow to compressor wheel and integrated in compressor housing of high pressure compressor - Google Patents

Abstract

The engine has two exhaust-gas turbochargers arranged in series, in which one turbocharger near the engine is designed as a high pressure turbocharger (2) with a high pressure turbine (4) and a high pressure compressor (5). Another turbocharger far from the engine is designed as a low pressure turbocharger (3) with a low pressure turbine and a low pressure compressor. An air flow adjusting device is implemented as an axial valve (52), which is arranged in a flow path of an air flow to a compressor wheel and integrated in a compressor housing of the high pressure compressor. An independent claim is also included for a method for operating an internal combustion engine.

Description

The The invention relates to an internal combustion engine with two in series switched exhaust gas turbocharger according to the preamble of the claim 1.

In the DE 101 44 663 B4 An internal combustion engine with two-stage supercharging is described, which is realized by two exhaust gas turbochargers connected in series. The close-coupled loader is designed as a high-pressure stage, the remote supercharger as a low-pressure stage, whereby a charge pressure build-up is already feasible at low loads and speeds of the internal combustion engine. In order to prevent overloading of the near-engine high-pressure turbine in the upper speed and load range, a high-pressure turbine bridging bypass is provided, which branches upstream of the high-pressure turbine from the exhaust line and downstream of the high-pressure turbine, but even before the low-pressure turbine in the exhaust line reboots. For pressure reduction in the wiring harness upstream of the high-pressure turbine, a blow-off valve is opened in the bypass, so that exhaust gas is passed around the high-pressure turbine. Another bypass with arranged therein by-pass valve is provided to bypass the remote engine low-pressure turbine. Depending on the current engine state, the exhaust gas can be guided around or around both exhaust gas turbines by means of the bypass valves in the bypass lines, whereby less energy is supplied to the relevant supercharger and the supercharger is only accelerated to a lower rotational speed.

Also The high pressure compressor is a bypass with bypass valve arranged therein assigned. When the compressor bypass is closed, the bypass valve acts as a check valve. In case of leaks in the bypass valve, however, it may be undesirable recirculation flows come to the compressor entry, which is associated with significant efficiency losses is. Another problem is the sudden change of the torque output by the internal combustion engine in the event that the compressor bypass is opened suddenly. This leaping torque change must be compensated by internal engine intervention.

Of the Invention is based on the object, the energy potential contained in the exhaust gas to increase the overall efficiency with simple constructive activities in an optimal way, while at the same time providing effective protection against component overloads be given at high loads and speeds of the internal combustion engine should.

These Task is according to the invention with the Characteristics of claim 1 solved. The dependent claims give expedient further education at.

at the internal combustion engine according to the invention the high pressure compressor is a Luftstromreguliereinrichtung for Setting and influencing the air flow in the intake system assigned, as in the compressor housing the high-pressure compressor integrated actuator is executed. This actuator is located inside the compressor housing of the high pressure compressor in the flow path of the Air flow to the compressor wheel. An actuating movement of the actuator causes a change in the air flow, which is guided to the compressor wheel, and thus a change the compressor efficiency and the boost pressure generated by the compressor. In this way it is possible Influence on the efficiency of the high pressure loader as well as on the Overall efficiency of the internal combustion engine solely by constructive activities to take inside the compressor housing of the high pressure compressor are provided. An external bypass on the compressor housing is not required, so no problems with Leaks in the bypass valve and thereby caused recirculation or with a sudden change the torque when opening of the bypass valve may occur. Rather, it is due to the influence of the air flow upstream the compressor wheel a continuous, steady adjustment in pressure build-up avoiding sudden changes possible, because the flow control due to inertia the compressor wheel with a torque-smoothing time delay enforced the boost pressure. In addition, unlike a valve opening at a Movement of the actuator to fear no sudden flow changes. In the solution according to the invention is the entire air flow in the intake tract through the high pressure compressor guided, wherein the narrowest, the air flow rate determining cross-section in high pressure compressor according to the current requirements on the Adjustment of the actuator is varied.

The actuator is expediently designed as axial slide, which is mounted axially displaceable in the compressor inlet passage upstream of the blade leading edge of the compressor wheel. By means of the axial slide, the flow to the compressor wheel is influenced. It is possible, for example, an embodiment of the high-pressure compressor with an additional channel provided in addition to the compressor inlet duct, via the combustion air to the compressor is fed and opens radially into the compressor inlet passage, wherein the axial slide can influence the cross-section of the orifice of the additional channel. This is done by way of example in that the axial slide forms a wall of the additional channel and the mouth opening between the end face of the axial slide and a housing portion of the compressor housing is arranged, so that in an axial adjusting movement of the Axial slide the cross-section of the mouth opening is varied. In this embodiment, the additional channel extends radially outside of the compressor inlet channel, the axial slide is expediently designed as a sliding sleeve and limits the additional channel radially inwardly.

The Mouth opening of the Additional channel is located advantageously axially equal to the compressor wheel blades of the compressor wheel. Due to the radial opening of the additional channel in the Compressor inlet channel hits the combustion air introduced via the additional duct with radial component on the compressor wheel blades, wherein additionally a flow component achieved in the circumferential direction by means of a swirl grid placed in the mouth opening may be, whereby the compressor impeller blades an additional Angular momentum from the over introduced the additional channel Experience combustion air. This mode of operation can in particular in so-called cold air turbine operation at low loads and Speeds of the internal combustion engine are performed, in which in the cylinder inlets a negative pressure prevails, so that above the high-pressure turbine, a pressure drop arises for An additional Drive the compressor wheel can be exploited.

at higher Loads and speeds, however, can be the additional channel for training a recirculation flow open in which a part of the supplied combustion air via the additional channel against the main flow direction returned and is introduced back into the compressor inlet passage. It deals this is a so-called map-stabilizing measure to prevent of the compressor pumping. At the same time thereby the air mass flow reduced, which is passed through the high-pressure compressor.

In the case, that no recirculation flow through the additional channel training is open Opening cross-section the additional channel to achieve a reduction in efficiency, since funded by the additional channel Partial air mass flow does not unfold the same effect on the compressor wheel as the axially introduced Air mass flow. The opening of the mouth cross-section between additional channel and compressor inlet channel in the area of the compressor wheel therefore results in a reduction in efficiency. So that the high pressure compressor with a corresponding request of a control and control unit the internal combustion engine can generate a maximum boost pressure, Therefore, the axial slide will be operated in such a way that the orifice between additional channel and compressor inlet channel is closed.

The Actuation movement of the axial slide is advantageously using a Actuator performed, which engages an adjusting lever, which is firmly connected to the axial slide is. The adjustment of the actuator is performed by control signals of Control and control unit in dependence of state and operating variables of Internal combustion engine or the internal combustion engine assigned Auxiliary units.

When Actuator, which influences the air flow towards the compressor wheel, also comes the compressor immediately axially upstream Gate valve in the compressor inlet passage into consideration, in whose axial adjusting movement which impinges axially on the compressor wheel airflow is varied. This gate valve can interact with the axial slide, which forms a wall of the additional channel and also the mouth opening between additional channel and compressor inlet channel limited. Arrives the gate valve the axial slide on and adjusted in the direction of the compressor wheel, so the mouth opening is between Additional channel and compressor inlet channel reduced and, where appropriate Completely closed. In this way, with only one actuator both the directly axially impinging on the compressor wheel air flow as also the over the additional channel influenced radially on the compressor impinging air flow become.

Further Advantages and expedient designs are the further claims, the figure description and the drawings. Show it:

1 a schematic representation of an internal combustion engine with two exhaust gas turbochargers connected in series, wherein the exhaust gas turbocharger close is designed as a high pressure supercharger, the compressor has an integrated in the compressor housing actuator for influencing the air mass flow, and the exhaust gas turbocharger remote engine is designed as a low-pressure supercharger,

2 a section through the high-pressure compressor of the high-pressure supercharger with an axial slide designed as an actuator, the axial slide an additional channel separated from the compressor inlet passage and via the additional channel a partial air mass flow is radially fed to the Verdichterradschaufeln, shown in the closed position of the axial slide,

3 a 2 corresponding representation, but with the axial slide in the open position, so that a mouth cross-section between the additional channel and the compressor inlet channel is released,

4 a swirl lattice in front view, in the mouth cross-section between additional channel and Compressor inlet channel is arranged,

5 a section through the low-pressure turbine of the low-pressure supercharger, in the turbine housing, a blow-off valve is integrated, which is associated with a high-pressure turbine bridging bypass.

In The figures are the same components with the same reference numerals.

In the 1 illustrated internal combustion engine 1 , which is a gasoline engine or a diesel engine, is provided with a two-stage supercharging, consisting of two exhaust gas turbochargers connected in series, of which the exhaust gas turbocharger close to the engine 2 designed as a high-pressure supercharger and the exhaust gas turbocharger remote engine as a low-pressure supercharger. The compact high-pressure loader 2 includes a high pressure turbine 4 in the exhaust system 8th and a high pressure compressor 5 in the intake tract 7 , wherein the rotational movements between the turbine wheel and the compressor wheel of the high pressure supercharger 2 over a wave 6 be transmitted. Similarly, the low pressure loader includes 3 a low pressure compressor 9 downstream of the high pressure compressor 4 in the exhaust system 8th and a low pressure compressor 10 upstream of the high pressure compressor 5 in the intake tract 7 , Between turbine wheel and compressor wheel in the high pressure loader 3 is a wave 11 connected.

The combustion air is via the intake tract 7 first the low-pressure compressor 10 supplied, in which a pre-compression of the combustion air takes place. Downstream of the low pressure compressor 10 is the first charge air cooler in the intake system 12 arranged to cool the precompressed air. In the course of the pre-compressed combustion air is the downstream high-pressure compressor 5 supplied, the compressor wheel in a compressor inlet channel 50 is rotatably mounted. Parallel to the compressor inlet channel 50 is in the compressor housing of the high pressure compressor 5 an additional channel 51 formed, which opens axially in the amount of Verdichterradschaufeln again in the compressor inlet passage. The cross section of the mouth opening between additional channel 51 and compressor inlet duct 50 is by means of an axial slide 52 changeable adjustable. In the mouth opening there is a swirl grid 53 , over which the over the additional channel 51 supplied combustion air is imparted a swirl under which the combustion air impinges on the compressor wheel blades.

Downstream of the high pressure compressor 5 is the further compressed combustion air in a second intercooler 13 cooled and then under boost pressure the cylinder inlets of the internal combustion engine 1 fed.

The exhaust side are those of the internal combustion engine 1 initially produced exhaust gases via the exhaust system 8th the high-pressure turbine 4 of the exhaust gas turbocharger close to the engine 2 fed, in which the turbine wheel is driven, its rotational movement over the shaft 6 on the compressor wheel in the high pressure compressor 5 is transmitted. Downstream of the high-pressure turbine 4 becomes the pre-expanded exhaust of the low-pressure turbine 9 fed, where the residual energy contained in the exhaust gas is used to drive the turbine wheel, its rotational movement over the shaft 11 on the compressor wheel in the low-pressure compressor 10 is transmitted. After passing the low-pressure turbine 9 The fully expanded exhaust gas is first in an exhaust gas purification device 20 cleaned and then discharged.

To bypass the high-pressure turbine 4 is a bypass 18 provided, the upstream of the high-pressure turbine 4 branches off from the exhaust system and directly into the turbine housing of the low-pressure turbine 9 opens. In the low-pressure turbine 9 is a by-pass 18 associated blow-off valve 19 integrated. With the blow-off valve open 19 will that be over the bypass 18 directed exhaust gas directly to the turbine wheel of the low-pressure turbine 9 directed.

The internal combustion engine 1 is still with an exhaust gas recirculation device 14 provided a return line 15 between the exhaust line 8th upstream of the high-pressure turbine 4 and the intake tract 7 downstream of the second, the high pressure compressor 5 downstream intercooler 13 includes. In the return line 15 the exhaust gas recirculation device 14 there is an adjustable shut-off valve 16 as well as an exhaust gas cooler 17 ,

All adjustable units of the internal combustion engine, depending on the state and operating variables of the engine and the units by means of actuating signals of a control and control unit 20 set. This concerns in particular the check valve 16 in the exhaust gas recirculation device 14 , the blow-off valve 19 of the bypass 18 which is in the low-pressure turbine 9 integrated, and the axial slide 52 in the high pressure compressor 5 for regulating the cross section of the orifice between the additional channel and the compressor inlet channel. In the control and control unit 21 various state variables are detected in the internal combustion engine, the boost pressure p ₂ is entered as an example, which is tapped downstream of the high pressure compressor.

In 2 is the high pressure compressor 5 shown in section. In the compressor inlet channel 50 is the compressor wheel 56 on the shaft 6 stored and rotated about the axis of rotation 58 , The over the compressor inlet channel 50 brought combustion air flows axially on the compressor wheel 56 and the comp terradschaufeln 57 and after passing the compressor wheel via a diffuser radially into a spiral channel 61 derived in the compressor housing 60 is formed, from which the compressed combustion air is first cooled under boost pressure in the intercooler and then fed to the cylinder inlets of the internal combustion engine.

In the compressor inlet channel is an axial slide 52 axially in the direction of the arrow 59 slidably mounted. This axial slide 52 , which is expediently designed as a sliding sleeve, at the same time forms a wall for an additional channel 51 , which is separate from the compressor inlet duct 50 is executed. About the additional channel 51 becomes the compressor wheel 56 Supplied combustion air; also possible is the formation of an oppositely directed recirculation flow, in which a partial air mass flow over the additional channel 51 is returned against the main flow direction to prevent so-called map-stabilizing measure an undesirable compressor pumps. The additional channel 51 is located radially outside the compressor inlet channel 50 , also the axial slide 52 is offset so far radially outward that the axial blade leading edge 65 without limitation from the axial across the compressor inlet duct 50 supplied combustion air can be flowed. The additional channel 51 has a radial mouth opening 54 in the compressor inlet channel 50 into it, which is axially equal to the compressor wheel blades 57 located so that over the additional channel 51 brought combustion air radially to the compressor wheel blades 57 incident. In the mouth opening 54 can be a vortex grid 53 be arranged to impart a twist to the supplied combustion air, under which the combustion air impinges on the compressor wheel blades, whereby the compressor wheel is added an additional angular momentum.

The cross section of the mouth opening 54 depends on the current axial position of the axial slide 52 off, the direction of the arrow 59 axially in the compressor inlet channel 50 is slidably mounted. The position of the axial slide 52 can by means of an actuator 63 be set. The vortex grid 53 , which is located in the mouth opening 54 is located on a housing portion of the compressor housing 60 attached and can be in a storage bag 55 are pushed, which are located on the front side of the axial slide 52 located.

The axial slide 52 is by a spring element 62 kraftbeaufschlagt, the axial slide 52 in one the mouth opening 54 enlarging position presses. The actuator 63 holds the current position of the axial slide 52 against the spring force of the spring element 62 or adjusts the axial slide against the spring force.

In the illustration after 2 is the axial slide 52 so far approximated to the housing wall, that only a narrow gap as the mouth opening 54 remains open. The vortex grid 53 is almost completely in this position of the axial slide in the receiving pocket 55 retracted. In this almost closed position of the axial slide 52 can no or only a small partial air mass flow through the additional channel 51 radially on the compressor wheel 56 incident.

In 3 is the high pressure compressor 5 in a retracted position of the axial slide 52 shown in which a relatively large cross-section of the mouth opening 54 is released and - as shown by the arrows - a partial air mass flow over the additional channel 51 and the mouth opening 54 radially on the compressor wheel blades 57 can hit. The withdrawn position according to 3 takes the axial slide 52 in particular in operating states of the internal combustion engine, in which an overload of the components to be avoided, for example, at exhaust gas back pressures, which are above a limit. Due to the introduction of the partial air mass flow over the additional channel 51 and the radial flow of the compressor wheel blades 57 a slight reduction of the overall efficiency of the compressor, so that in the compressor, a lower boost pressure is generated and consequently the filling of the cylinder of the engine fails lower, which in turn leads to a reduction of the exhaust backpressure. In the event that the high pressure compressor 5 must generate the full boost pressure, however, the axial slide 52 in the in 2 shown position with closed or only minimally open mouth cross-section 54 adjusted. Since in the closed position of the axial slide the entire air mass flow axially over the compressor inlet passage 50 on the compressor wheel 56 impinges, an optimal efficiency is achieved in the compressor.

As in 3 Plotted with dashed line, can in the compressor inlet duct 50 an additional gate valve 64 be mounted axially displaceable over which the air mass flow is adjustable, via the compressor inlet passage 50 is passed axially on the compressor wheel. Will the gate valve 64 axially to the axial slide 52 Approximated, the supplied combustion air flows mainly through the additional channel 51 on the compressor wheel 56 ; this position of the locking slide 64 goes hand in hand with a reduction in efficiency. In addition, the gate valve 64 also as an actuator for the adjustment of the axial slide 52 be used, so on another actuator 63 can be waived. The front side of the gate valve 64 touched when approaching the axial slide 52 whose end face and presses the axial slide against the force of the spring element 22 in a the Cross section of the mouth opening 54 reducing position. When returning the gate valve 64 takes the axial slide 52 due to the force of the spring element 62 again automatically a cross section of the mouth opening 54 increasing position.

In 4 is a plan view of the swirl grid 53 shown, which is located in the mouth opening of the additional channel 51 to the compressor inlet channel 50 located. The swirl lattice is annular with individual, circumferentially extending vanes 66 , wherein between each two adjacent vanes, a flow gap is released, through which the supplied combustion air flows through and then impinges on the Verdichterradschaufeln. About the geometry of the vanes 66 and the intermediate flow gaps can be imparted to the supplied combustion air a swirl, under which this impinges on the Verdichterradschaufeln.

In 5 is a section through the low-pressure turbine remote from the engine 9 shown. In the turbine housing 22 is an exhaust gas flow 23 formed, in which the introduced via the exhaust gas exhaust gas is introduced under pressure. The exhaust gas flow 23 is radial to the turbine wheel 24 upstream, the exhaust gas flows from the exhaust gas flow 23 via an opening cross-section to the turbine wheel 24 and hits the turbine blades 25 on, which are driven by the exhaust gas. In the course of the relaxed exhaust gas is axially from the turbine 9 via a turbine outlet 34 derived. The rotational movement of the turbine wheel 24 will be over the shaft 11 transferred to the low pressure compressor.

Approximately parallel to the exhaust gas flow 23 is located in the turbine housing a plenum 26 smaller cross-section, in which the bypass 18 opens, which bypasses the high-pressure turbine 4 ( 1 ) is provided. This collection room 26 is over a mouth cross-section 29 radially with the turbine wheel 24 connected to receiving space. The mouth cross-section 29 is via a radially extending partition wall 30 from the mouth cross-section between the exhaust gas flow 23 and turbine wheel 24 separated. At the partition 30 are vanes 31 arranged, which must pass the exhaust gas mass flow, which from the plenum 26 over the mouth cross-section 29 radially on the turbine blades 25 flows. The mouth cross-section 29 is variably adjustable here. For this is a die 27 axially in the direction of the arrow 28 in the turbine housing 22 slidably mounted, with the die 27 a receiving opening 32 has, in which the vanes 31 approaching the die 27 to the partition 30 can be retracted. In the embodiment according to 5 is the axial width of the mouth cross-section 29 as entered h. The mouth cross-section 29 can be closed completely if necessary. The collection room 26 and the die acting as a valve member 27 together form a blow-off valve 19 , which as internal, in the low-pressure turbine 9 integrated valve bypass 18 assigned. With the blow-off valve open 19 the exhaust back pressure is upstream of the high pressure turbine 4 reduced, which component overloads in the high-pressure charger can be avoided.

Claims (13)

Internal combustion engine with two exhaust gas turbochargers connected in series ( 2 . 3 ), of which the close-coupled loader as high-pressure loader ( 2 ) with a high-pressure turbine ( 4 ) and a high pressure compressor ( 5 ) and the remote engine loader as a low-pressure loader ( 3 ) with a low-pressure turbine ( 9 ) and a low pressure compressor ( 10 ), wherein the high-pressure compressor ( 5 ) an air flow regulating device for regulating the air flow in the intake tract ( 7 ), characterized in that the air flow regulating means as a in the compressor housing ( 60 ) of the high pressure compressor ( 5 ) integrated, in the flow path of the air flow to the compressor wheel ( 56 ) arranged actuator ( 52 ) is executed. Internal combustion engine according to claim 1, characterized in that the actuator as axial slide ( 52 ) is executed, which is axially displaceable in the compressor inlet channel ( 50 ), wherein over the axial slide ( 52 ) an orifice ( 54 ) one in addition to the compressor inlet duct ( 50 ) additional channel ( 51 ) and the mouth opening ( 54 ) of the additional channel ( 51 ) radially into the compressor inlet channel ( 50 ). Internal combustion engine according to claim 2, characterized in that the orifice ( 54 ) axially in the amount of the compressor wheel ( 56 ) into the compressor inlet duct ( 50 ). Internal combustion engine according to claim 2 or 3, characterized in that the axial slide ( 52 ) a wall of the additional channel ( 51 ). Internal combustion engine according to one of claims 2 to 4, characterized in that in the mouth opening ( 54 ) a swirl grid ( 53 ) is arranged. Internal combustion engine according to one of claims 2 to 5, characterized in that the axial slide ( 52 ) the blade leading edge ( 65 ) of the compressor wheel ( 56 ) radially outside the compressor wheel blades ( 57 ) overlaps. Internal combustion engine according to one of the claims che 1 to 6, characterized in that of the two compressors ( 5 . 10 ) excluding the high-pressure compressor ( 5 ) is associated with a Luftstromreguliereinrichtung. Internal combustion engine according to one of claims 1 to 7, characterized in that the actuator as a the compressor wheel ( 56 ) axially upstream locking slide ( 64 ) in the compressor inlet duct ( 50 ) is executed. Internal combustion engine according to claim 2 and 8, characterized in that the locking slide ( 64 ) in addition to the axial slide ( 52 ) is provided and the gate valve 64 ) the axial slide ( 52 ) adjusted. Internal combustion engine according to one of claims 1 to 9, characterized in that in the exhaust system ( 8th ) a high-pressure turbine ( 4 ) bridging bypass ( 18 ) is provided. Internal combustion engine according to claim 10, characterized in that in the bypass ( 18 ) a bypass valve ( 19 ) arranged in the low-pressure turbine ( 9 ) is integrated. Method for operating the internal combustion engine according to one of claims 1 to 11, characterized in that as an overload protection when exceeding an exhaust back pressure limit value or a value correlated therewith, the actuator ( 52 ) into a mass flow rate through the compressor ( 5 ) reducing position is adjusted. Method according to Claim 12 for operating an internal combustion engine with an axial slide ( 52 ) according to claim 2 as an actuator, characterized in that the axial slide ( 52 ) into a mouth opening ( 54 ) of the additional channel ( 51 ) releasing or enlarging position is adjusted.