DE10132672A1 - Exhaust gas turbocharger for internal combustion engine enables different flow rates through exhaust gas openings to be set by altering valve body position - Google Patents

Abstract

The device has an exhaust gas turbine (3), a valve housing forming a common component with an exhaust gas turbine housing and a valve body in the valve housing for opening and closing first and second outlet openings associated with first and second exhaust gas channels. Different flow rates through the openings can be set by altering the valve body position.

Description

The invention relates to an exhaust gas turbocharger for a Internal combustion engine according to the preamble of claim 1.

From the document DE 198 57 234 C2 is an exhaust gas turbocharger for an internal combustion engine, whose exhaust gas turbine a double spiral duct, with each exhaust gas flow in the Spiral channel communicates with one exhaust pipe, via the exhaust gas each to supply a cylinder bank of the internal combustion engine is. One of the two exhaust pipes is with a Exhaust gas recirculation line for the return of exhaust gas into the intake tract connected, wherein the recirculated exhaust gas mass flow over a Set valve device is. Moreover, one is the Exhaust gas bypass bridging provided, the over a Bypass valve is open, which is connected to both exhaust pipes is.

During operation of the internal combustion engine can load and Depending on the status, the exhaust gas recirculation valve and / or the blow-off valve are opened to reduce nitrogen oxide emissions Part mass flow of the exhaust gas in the intake or recycle Blow off exhaust gas and a mechanical and thermal To avoid overloading the engine and the turbocharger. The The valves are adjusted via control signals of a control and control unit.

A double-flow gas turbine of an exhaust gas turbocharger is also off DE 198 36 677 A1. According to this document is on the turbine housing a rotary valve placed, which in the Flow path of a bypass to the exhaust gas turbine is located and a hollow cylindrical rotary body with two outlet openings for each Exhaust gas flow has. The outflow openings are as grooves in the Wall of the rotary body introduced in the circumferential direction of the Run rotary body and are arranged parallel to each other and both have the same length. During a rotation of the Rotary bodies enter the outflow openings simultaneously Open or in locked position, so that from both exhaust gas flows is evenly discharged through the bypass.

Starting from this prior art, the invention is the Problem based, with simple means an exhaust gas turbocharger with a double-flow exhaust gas turbine, in which too an asymmetric blow-off from the two exhaust gas floods possible is.

This problem is inventively with the features of Claim 1 solved.

The valve housing of the valve device is connected to the housing Connected exhaust gas turbine and forms a common with this Component, wherein both a one-piece design and a two-piece design with separate housing parts, however are firmly connected, comes into consideration. In the valve housing is a common valve body for both exhaust gas flows arranged in each case in the valve body for each exhaust gas flow Provided outflow or over the valve body to is wrong. The outflow openings and the valve body are in the way matched that over a change of the Position of the valve body different high mass flows adjustable by the first and by the second outflow opening are. This version allows asymmetric blow-off of exhaust gas from the two exhaust fumes. It is thereby the Possibility opened in the two exhaust fumes to set different pressure conditions, which is both for a Exhaust gas recirculation positively utilized especially in the partial load range can be as well as for a variably adjustable flow on the turbine wheel, for example in the case of a semi-axial and radial flow of the turbine wheel via one in each case Exhaust flow, can be used.

The different influxes on the turbine wheel over Each exhaust gas flow can also be advantageous with a variable Turbine geometry can be combined, which outdoors Flow cross-section can be arranged to the turbine wheel; the variable Turbine geometry can either only in the flow cross-section an exhaust gas flow to the turbine wheel or in both Flow cross sections of the two exhaust gas flows may be arranged.

The asymmetric blow-off, for example, by Outflow realized with different size cross section become. When adjusting the valve body blocked different sized sections of the outlet openings or released, allowing the derived from each exhaust flow Exhaust gas mass flow can be influenced individually.

The valve body can be either one-piece or two-piece be executed. In the one-piece design is the Relative position of the two outflow openings to each other immutable established. The asymmetric blow-off is in this case in particular over different sized cross sections of Outflow openings reached. The position of the valve body is to influence over an actuator, in the case of a one-piece valve body a single actuator is sufficient is. The valve body can be moved axially and / or around its Be twisted longitudinal axis.

In the case of a two-part valve body are the Outflow openings arranged in different parts of the valve body or are the valve body between barrier and Opening position adjusted. The two parts of the valve body are advantageous decoupled and can each have an actuator be set. In this design can be an asymmetric Blowing even with similar outflow openings exclusively about a different attitude each Valve body part can be achieved. Optionally, but also at a two-piece valve body outlet openings with different cross section are used.

Advantageously, an exhaust gas recirculation device between one of the two exhaust pipes and the intake of the Internal combustion engine provided, wherein the exhaust gas recirculation line of the Exhaust gas recirculation device via one of the two Outflow openings of the valve devices to open or close is. The second outflow opening is preferred for opening and Closure of a bypass to bypass the exhaust gas turbine provided. This embodiment can be used in particular in combination with a two-piece valve body with decoupled setting each Outflow opening can be used. At coupled Outlet openings - either in one-piece or two-piece Design of the valve body - are advantageous both exhaust gas flows via the outflow openings with a bypass to bypass the Turbine connected.

The two exhaust gas flows point in an advantageous development different cross-sectional geometries, thereby different pressure conditions in the exhaust gas flows and also different flow conditions in the direction of the Turbine are feasible. With decoupled outflow openings It may be useful here, the exhaust gas flow with smaller Cross section to connect with that exhaust pipe, from the the exhaust gas recirculation line branches off to the intake tract, since in the smaller exhaust gas higher pressures can be realized, the one positive, an exhaust gas recirculation favoring pressure gradient in Support direction intake.

Further advantages and expedient designs are the further Claims, the description of the figures and the drawings remove. Show it:

Fig. 1 is a schematic representation of a supercharged internal combustion engine with an exhaust gas turbine with two exhaust gas flows, which are each connected to an exhaust pipe, wherein the exhaust gases of one cylinder bank of the engine are to be paid on each exhaust line,

Fig. 2 is a two-part valve device which is integrated into the turbine housing of the turbocharger,

Fig. 3 is a one-piece, integrated in the turbine housing valve means,

Fig. 4 is a diagram showing the engine braking performance in dependence on the engine speed, shown for minimum and maximum blow-off,

FIG. 5 is a graph of turbine inlet pressure versus engine speed plotted for each of the two turbine exhaust flows, depending on the degree of blowdown; FIG.

Fig. 6 is a graph showing the boost pressure and the turbine inlet pressure as a function of time during the acceleration phase of the turbocharger.

In the following figures are the same components with the same Provided with reference numerals.

The internal combustion engine illustrated in Figure 1 1 -. A diesel engine or a gasoline engine - is associated with a turbocharger 2 which comprises an exhaust gas turbine 3 in the exhaust line 4 of the internal combustion engine and a compressor 5 in the intake duct 6, wherein the turbine wheel of the exhaust gas turbine 3 from the under increased exhaust gas back pressure standing exhaust gases of the internal combustion engine is driven and the turbine wheel is transmitted via a shaft 7 to the compressor wheel, sucked by the movement under atmospheric pressure near ambient air p ₁ standing ambient air and compressed to an elevated pressure p ₂ . Downstream of the compressor 5 is a charge air cooler 8 in the intake tract 6 ; After flowing through the charge air cooler 8 , the cooled charge air is supplied to the cylinder inlet of the internal combustion engine 1 under the boost pressure P _2s .

The internal combustion engine 1 comprises two cylinder banks 1 A and 1 B, each having a plurality of cylinders. The exhaust gases of the cylinder banks 1 A and 1 B are discharged separately via two exhaust gas lines 4 A and 4 B of the exhaust line 4 and under the exhaust back pressure p _3A and p _3B respectively an exhaust gas flow of a turbine volute 19 A and 19 B of the exhaust gas turbine 3 (see FIG . fed 2 and 3).

Furthermore, an exhaust gas recirculation 9 is provided for returning a partial mass flow of the exhaust gas from the exhaust gas line 4 into the intake tract 6 . Exhaust gas recirculation 9 comprises a return line 10 which branches off upstream of exhaust gas turbine 3 from first exhaust line 4 A, which is assigned to first cylinder bank 1 A, which opens into intake section 6 downstream of intercooler 8 and in which an exhaust gas cooler 11 is arranged. The amount of recirculated exhaust gas is regulated via a valve 12 A in the region of the branch of the return line 10 from the first exhaust line 4 A, wherein the valve 12 A is part of a valve device 12 .

The valve device 12 is associated with a further valve 12 B, which is arranged in the junction of a bypass 13 of the second exhaust pipe 4 B to bypass the exhaust gas turbine 3 . The bypass 13 opens downstream of the exhaust gas turbine 3 again into the exhaust gas line, from which the now expanded exhaust gas is discharged under the pressure p ₄ or subjected to a catalytic purification. The two valves 12 A and 12 B of the valve device 12 are adjusted via an actuator 14 A, 14 B between their blocking position and its open position, wherein the actuating movements of the two actuators 14 A and 14 B may be coupled, as indicated by dotted line in FIG illustrated. 1,. Alternatively, it may also be appropriate to form the two actuators 14 A and 14 B for the valves 12 A and 12 B independently operable.

The exhaust gas turbine 3 is equipped with a variable turbine geometry 15 , via which the free flow cross section to the turbine wheel of the exhaust gas turbine is variably adjustable.

Furthermore, a control and control unit 16 is provided, via which the functions of the various, the internal combustion engine 1 associated units is set. Depending on the state and operating variables of the internal combustion engine and the various units, in particular the valves 12 A and 12 B of the valve device 12 and the variable turbine geometry 15 are set.

As shown in FIG. 2, the turbine housing 18 of the exhaust gas turbine 3 forms a common component with the valve housing 20 of the valve device 12 ; Exhaust gas turbine and valve device are combined into one component. The valve device 12 comprises the two valves 12 A and 12 B, of which the first valve 12 A is associated with a first exhaust gas flow 19 A of the turbine volute 19 of the exhaust gas turbine and in the open position the first exhaust gas flow 19 A connects with the return line 10 of the exhaust gas recirculation, whereas the second valve 12 B, the second exhaust gas flow passage 19 connects B of the turbine scroll 19 in the open position to the bypass. 13 In the blocking position, the valves 12 A and 12 B are closed, so that the communication between the exhaust gas flows 19 A and 19 B and the return line 10 and the bypass 13 is interrupted; a blowdown of the introduced into the exhaust gas flows 19 A and 19 B exhaust gas is prevented in the blocking position of the valves.

The valves 12 A and 12 B have a valve body 21 , which is designed in the embodiment as a rotary body or rotary valve, which is to be adjusted during rotation about its longitudinal axis 22 between the locked and open positions. The valve body 21 is designed in two parts in the embodiment of FIG. 2 and includes a first valve body part 21 A, which is associated with the first valve 12 A, and a second valve body part 21 B, which is associated with the second valve 12 B. Both valve body parts 21 A and 21 B have the same longitudinal axis 22 and can rotate to the transfer between the locked and open position to this. Each valve body part 21 A and 21 B is assigned its own actuator to allow independent, decoupled adjustment between closed and open position.

Each exhaust gas flow 19 A and 19 B communicates via a respective discharge opening 23 A and 23 B in the turbine housing 18 with the valve means 12 , via the valve 12 A, the outflow opening 23 A of the first exhaust gas flow 19 A to open or is to block and via the second valve 12 B, the outflow opening 23 B of the second exhaust gas flow 19 B is set. In the illustration of Fig. 2, the valve 12 A is in its blocking position, the second valve 12 B is on the other hand open.

In the valve body parts 21 A and 21 B discharge openings 27 A and 27 B are introduced, which are passed as radial channels through the valve body parts 21 A and 21 B and the stationary outflow openings 23 A and 23 B are assigned in the turbine housing 18 . Upon rotation of the valve body parts 21 A and 21 B enter the outflow openings 27 A and 27 B in a communication position (open position) with the outflow openings 23 A and 23 B or in an external communication position (blocking position).

The two exhaust gas flows 19 A and 19 B have a different cross-section. The first exhaust gas flow 19 A, which communicates with the exhaust gas recirculation via the valve 12 A, has a smaller volume than the second exhaust gas flow 19 B, the exhaust gas is blown off via the second valve 12 B in the bypass 13 . Due to the separate, decoupled adjustment possibility of the two valves 12 A and 12 B in conjunction with the different sized volumes of the two exhaust gas flows 19 A and 19 B, an asymmetric blow-off of the contents of the respective exhaust gas flow, taking into account exhaust gas recirculation in the partial load range of the internal combustion engine and a pressure relief be performed via the bypass 13 to reduce thermal and mechanical loads in the full load range of the internal combustion engine.

The variable turbine geometry 15 is realized in the embodiment of FIG. 2 as axially in the radial flow cross section 24 between the exhaust gas flows 19 A and 19 B and the turbine wheel 17 . The guide grid may in this case have two different grids 25 A and 25 B, which are associated with the exhaust gas flows 19 A and 19 B and in the respective, each exhaust gas flow associated portion of the flow cross-section 24 are introduced.

Suitably, the two separated by a partition 26 exhaust gas flows 19 A and 19 B are pressure-tight shielded from each other.

In Fig. 3, a valve device 12 of an alternative embodiment is shown. The turbine housing 18 and the valve housing 20 are in turn made in one piece, however, the valve device itself has, in contrast to the previous embodiment, a one-piece valve body 21 , which is designed as a rotary body or rotary valve and outflow openings 27 A and 27 B for the valves 12 A and 12 B, which communicate in the open position of the valves with corresponding outflow openings 23 A and 23 B of the exhaust gas flows 19 A and 19 B. Due to the one-piece nature of the valve body 21 , the adjusting movement of both valves 12 A and 12 B is coupled. In the open position of the valves, the exhaust gas content from the exhaust gas flows 19 A and 19 B is discharged via the designed as a hollow cylinder valve body 21 axially from the valve device 12 and guided in particular in the bypass 13 to bypass the exhaust gas turbine.

The two outflow openings 27 A and 27 B in the valve body 21 have a different cross-sectional geometry and advantageously also a different surface area, whereby an asymmetric blow-off of the exhaust gas in the two exhaust gas flows 19 A and 19 B can be adjusted. Appropriately, the outflow openings 27 A and 27 B are arranged angularly offset on the circumference of the valve body 21 , whereby the outflow openings 27 A and 27 B at a rotation of the valve body 21 about its longitudinal axis 22 at different times in overlap with the respective corresponding flow openings 23 A and 23 B get the exhaust fumes; As a result, an asymmetrical blow-off of the gas content of the exhaust gas floods can likewise be set.

The valve body 21 is to be adjusted via the actuator 14 between locking position and open position. The actuator 14 is designed for example as a pressure cell.

In Fig. 4, the engine braking power P _Br , which is set via the turbocharger, shown in dependence on the engine speed n _{Mot of} the internal combustion engine. Plotted is a braking power range between a lower limit curve P _{Br, min} , which represents the minimum engine braking power, and an upper limit curve P _{Br, max} , which indicates the maximum achievable engine braking power. The minimum engine braking power P _{Br, min} is adjustable in the event that the outflow openings 23 A and 23 B and 27 A and 27 B of the valve device shown in FIGS . 2 and 3 are maximally open, so that the exhaust gas content in the two exhaust gas flows is derived in the greatest possible way. In this case, the pressure level in the exhaust gas turbine and in the exhaust pipes between the cylinder outlet of the internal combustion engine and the exhaust gas turbine is reduced to a minimum value, which results in a correspondingly low braking power level. The braking power _maximum P _{Br, max} is, however, achieved in the event that the valves of the valve devices are in the blocking position, so that the outflow openings are closed and the exhaust gas content can not be discharged via the outflow openings in the exhaust gas recirculation and / or the bypass. The pressure level is greatest in this case, resulting in the correspondingly high engine braking performance.

FIG. 5 shows the turbine inlet pressure or exhaust gas back pressure p _3A and p _3B for each exhaust gas line or for each exhaust gas flow as a function of the engine speed n _Mot . The solid line shows the exhaust back pressure p _3A , the dashed line the exhaust back pressure p _3B . The exhaust back pressure moves between both the lower and upper maximum for both exhaust flows, the exhaust back pressure p _{3A associated} with the first exhaust flow covering a wider range than the exhaust back pressure p _{3B associated with} the second exhaust flow moving within the exhaust pressure range of p _3A . The difference is due in particular to the different cross-section or the different volume of the two exhaust gas flows, wherein higher exhaust back pressures are to be set in the smaller of the two exhaust gas flows. The lower limit curve for each exhaust gas back pressure p _3A or p _3B is reached when the respectively associated valve is opened to the maximum. The upper limit curve is reached in the closed valve position.

In Fig. 6, the boost pressure p ₂ and the exhaust back pressures p _3A and p _3B for the startup phase of the turbocharger are shown time-dependent. The exhaust backpressure curve p _{3A of} the smaller exhaust gas flow generally moves to a higher level than the exhaust gas back pressure p _{3B of} the larger exhaust gas flow represented by a dashed line. The boost pressure p ₂ is in all operating ranges of the internal combustion engine below the exhaust back pressure p _{3A of} the first, smaller exhaust gas flow, whereby a positive, an exhaust gas recirculation enabling pressure gradient between the first exhaust gas flow and the exhaust gas line associated with this exhaust gas is given. The exhaust gas back pressure p _{3B of} the second exhaust gas flow during startup of the turbine in the lower run-up region is likewise above the charge pressure p ₂ , so that in this region there is likewise a positive pressure gradient from the exhaust gas side in the direction of the intake tract. In the upper operating range, the exhaust back pressure curve p _{3B of} the second exhaust gas flow decreases after a short increase to a value above the exhaust back pressure curve p _3A below the level of the boost pressure p ₂ .

Claims (13)

1. Exhaust gas turbocharger for an internal combustion engine, with one of the exhaust gas of the internal combustion engine ( 1 ) driven exhaust gas turbine ( 3 ) in the exhaust line ( 4 ) and one of the exhaust gas turbine ( 3 ) driven compressor ( 5 ) in the intake tract ( 6 ) of the internal combustion engine ( 1 ), wherein a turbine coil ( 19 ) in the exhaust gas turbine ( 3 ) comprises two exhaust gas flows ( 19 A, 19 B) communicating with a respective exhaust pipe ( 4 A, 4 B) of the exhaust line ( 4 ), one between a blocking position and an open position characterized in that the valve housing ( 20 ) of the valve device ( 12 ) with the turbine housing ( 18 ) of the exhaust gas turbine ( 3 ) has a common valve body ( 12 ) for variable adjustment of the exhaust gas flows ( 4 A, 4 B) supplied exhaust gas mass flow Part forms and that in the valve housing ( 20 ) a valve body ( 21 ) is arranged, via which a first, the first exhaust gas flow ( 19 A) associated Abströmöffnu ng ( 23 A, 27 A) and a second, the second exhaust gas flow ( 19 B) associated discharge opening ( 23 B, 27 B) to open or close, wherein a change in the position of the valve body ( 21 ) different high mass flows through the first and through the second outflow opening ( 23 A, 27 A and 23 B, 27 B) are adjustable. 2. Exhaust gas turbocharger according to claim 1, characterized in that the outflow openings ( 23 A, 27 A and 23 B, 27 B) have a different cross-section. 3. Exhaust gas turbocharger according to claim 1 or 2, characterized in that via an outflow opening ( 23 A, 27 A) an exhaust gas recirculation line ( 10 ) between an exhaust pipe ( 4 A) an exhaust gas flow ( 19 A) and the intake tract ( 6 ) to open and to close. 4. Exhaust gas turbocharger according to one of claims 1 to 3, characterized in that via a discharge opening ( 23 B, 27 B), a bypass ( 13 ) between the exhaust pipe ( 4 B) an exhaust gas flow ( 19 B) and the exhaust line ( 4 ) downstream the exhaust gas turbine ( 3 ) to open and close. 5. Exhaust gas turbocharger according to claim 4, characterized in that via both outflow openings ( 23 A, 27 A and 23 B, 27 B), a bypass ( 13 ) to the exhaust gas turbine ( 3 ) to open and close. 6. Exhaust gas turbocharger according to one of claims 1 to 5, characterized in that the valve body ( 21 ) is designed as a hollow cylinder and the outflow openings ( 27 A and 27 B) are introduced into the wall of the hollow cylinder. 7. Exhaust gas turbocharger according to one of claims 1 to 6, characterized in that the valve body ( 21 ) is designed as a one-piece component and the relative position of the two outflow openings ( 27 A and 27 B) is immutable to each other, wherein a position of the valve body ( 21 ) influencing actuator ( 14 ) is provided. 8. Exhaust gas turbocharger according to one of claims 1 to 6, characterized in that the valve body ( 21 ) is designed in two parts and the outflow openings ( 27 A, 27 B) in different parts ( 21 A, 21 B) of the valve body ( 21 ) are arranged , 9. Exhaust gas turbocharger according to claim 8, characterized in that the two parts ( 21 A, 21 B) of the valve body ( 21 ) are decoupled and the position of each part ( 21 A, 21 B) via one actuator ( 14 A, 14 B ) is to be adjusted. 10. Exhaust gas turbocharger according to one of claims 1 to 9, characterized in that the two exhaust gas flows ( 19 A, 19 B) have a different cross-sectional geometry. 11. Exhaust gas turbocharger according to claim 10, characterized in that the reduction of exhaust backpressure (p _3A , p _3B ) of the smaller exhaust gas flow ( 19 A) associated discharge opening ( 23 A, 27 A) is first opened. 12. Exhaust gas turbocharger according to one of claims 1 to 11, characterized in that the valve body ( 21 ) is designed as a rotary valve. 13. Exhaust gas turbocharger according to one of claims 1 to 12, characterized in that in the flow cross section ( 24 ) to the turbine wheel ( 17 ) a variable turbine geometry ( 15 ) is arranged.