DE102004028482A1 - Internal combustion engine has two turbo-superchargers driven by exhaust gas each with own exhaust gas line of group of valves, with cylinder connected on outlet side to both superchargers - Google Patents

Abstract

Internal combustion engine (10) has two turbo-superchargers (18,22) whose compressor (19,23) is driven by gas discharged from turbines (20,24). The first turbo-supercharger is arranged in a first exhaust gas line (16) of a first group of exhaust valves (14) and a second turbo-supercharger in a second exhaust gas line (17) of a second group of exhaust valves (15). At least part of the cylinder (11) of the combustion engine is connected on the outlet valve side to both turbo-superchargers.

Description

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

The use of exhaust gas turbochargers for charging gasoline and diesel engines is known. At low engine speeds and exhaust gas mass flows, the charge pressure build-up takes place with a certain delay, and the resulting delayed torque build-up in the turbo engine is noticeable as a "turbo lag." Turbocharged engines generally aim to increase their output compared to naturally aspirated engines.The degree of the desired power increase also increases the size of the required engine However, the requirement for simultaneously high performance and small turbo lag at low engine speeds is difficult to meet with a single turbocharger, so it has already been proposed to have two exhaust gas turbochargers per engine Engine having improved response due to the smaller turbines and compressors compared to a single turbocharger design Such a dual turbocharged arrangement For example, in the DE 19743667 A1 described.

task The present invention is the torque buildup of a turbo engine continue to improve at low speeds.

The Task is according to the invention with the features of claim 1.

at the internal combustion engine according to the invention with a turbocharger device having at least a first and a second turbocharger whose compressor is acted upon by exhaust gas Turbines is drivable, the first turbocharger is in a first Exhaust line of a first group of exhaust valves of the internal combustion engine and the second turbocharger in a second exhaust line of a second Group of exhaust valves arranged. The first turbocharger is from the exhaust valves of the first group and the second turbocharger acted upon by the exhaust valves of the second group, wherein at least a part, preferably all, the cylinder of the internal combustion engine outlet side is connected to two turbochargers. This means, that always only a part of the exhaust valves of at least one part the cylinder is acted upon by at least two turbochargers. It makes sense in addition Valve lift and / or timing of the individual exhaust valves of a Cylinder independent provide adjustable from each other. There are at least two exhaust valves per Cylinder provided. At least one cylinder head is preferred two turbochargers, especially exactly two turbochargers provided. The internal combustion engine is preferably spark-ignited, particularly preferably direct-injection educated.

advantageous Further developments of the invention are specified in subclaims.

Prefers the first turbocharger is smaller than the second turbocharger. It makes sense for the second turbocharger to the rated power of the internal combustion engine designed. In particular, the first turbocharger is significantly smaller designed as the second turbocharger and so small-sized, that a spontaneous response and a rapid torque build-up in the lower Speed range guaranteed is. The turbine of the second turbocharger is preferably designed to be larger than with a comparable one-stage charge. Advantageous is the vote between the at least two turbochargers so designed to create a harmonious transition between operation with the first and second turbochargers. Cheap, then run the first turbocharger with a twin-bladed turbine as a so-called "twin-scroll" loader at a particularly low exhaust back pressure can be achieved if the Control times for both groups of exhaust valves are the same, especially when no short timings for the exhaust valves of the first group are provided, or if to achieve low levels of pollutants in the exhaust gas mass flow late Aiming to close the exhaust becomes.

Preferably is at least part of the second turbocharger acting Outlet valves designed to be switched off, are particularly preferred all the exhaust valves acting on the second turbocharger in the flow at least reducible, ideally switchable. The advantage is, that at low speeds and exhaust gas mass flows, the entire exhaust exclusively the first turbocharger or its turbine flows through. The shutdown can be in known form of valve deactivation, for example as articulated trunks, or as fully variable valve train or the like accomplished become.

In a favorable embodiment, the exhaust valves acting on the first turbocharger may be configured differently in diameter from the exhaust valves acting on the second turbocharger. Preferably, these exhaust valves acting on the first turbocharger have a smaller diameter. In particular, when the exhaust valves acting on the first turbocharger are made smaller in diameter, when the two turbochargers act on one another Divide the exhaust gas mass flow in favor of the second exhaust gas turbocharger. Preferably, the first turbocharger without bypass circuit, ie without so-called "waste gate" executed.

In another cheap Design may be a Ventilhubkurve and / or a duration of the valve opening and / or Valve timing of the exhaust valves of the first group of which Exhaust valves of the second group to be different. Preferably have the members of the first group, the first turbocharger acting exhaust valves shorter timing on as the second group, the second turbocharger acting exhaust valves.

In a cheap one Further development are for charging the second turbocharger provided switched-off exhaust valves with increasing exhaust gas mass flow gradually activated. Is then at an increase in the mass flow, for example, during an acceleration process from low speed, Requiring the second turbocharger, the dynamic Torque history of the second turbocharger can be improved. An advantageous Operating mode results when the turn-off exhaust valves be activated step by step, e.g. in a 6-cylinder engine by connecting in six, three or two steps to one, two or three exhaust valves. Appropriately, the activation takes place in an N-cylinder engine in N / m increments, where m is an integer with 1 ≤ m ≤ N. Logically, is the relationship N / m is an integer. The connection can preferably be time-dependent and / or load dependent and / or speed-controlled or speed-controlled depending on a Suction pipe pressure downstream of the compressor done.

In a cheap one Further training is the design of an exhaust gas purification system to the configuration adapted to the preferred turbocharger device. Preferably provided in the first exhaust line, a first catalytic converter, preferably a small volume, close to the engine precatalyst, which in Exhaust gas flow direction seen before or behind the first turbocharger can be arranged.

Cheap, in the exhaust gas flow direction behind the second turbocharger a second catalyst after a together to provide the first and second exhaust line. Is preferred the second catalyst is a main catalyst. During a heating up phase of the Exhaust gas aftertreatment is first only the first turbocharger charged until the second catalyst has reached its predetermined minimum operating temperature. Advantageous It follows that the low exhaust back pressures to improve the combustion process to lead with a consequent improvement in torque increase and Consumption advantages in fuel consumption. The second turbocharger can in the alternative, be charged to the first turbocharger at this stage to relieve, if the resulting exhaust gas mass flow to an impermissible operating state lead the first turbocharger would. Conveniently, the second catalyst is larger in volume than the first catalyst, preferably 1.5 times larger twice as big or four times as big.

by virtue of the preferred flow of the first turbocharger in the warm-up phase, an exhaust gas sensor simplified become. Preferably, upstream of the first catalyst and downstream of the second catalyst each have an oxygen-sensitive measuring device intended. The first oxygen-sensitive measuring device upstream of the first catalyst may be in front of or behind the first turbocharger be arranged. It is advantageously a broadband lambda probe used. The second oxygen-sensing measuring device downstream of the second catalyst may preferably for trim control as a lambda probe be trained with a step response. For individual monitoring of the Catalysts and / or increased exhaust gas monitoring can be a third oxygen-sensitive measuring device downstream of the first catalyst and be provided upstream of the second catalyst. A convenient installation position the third oxygen-sensitive measuring device is after the merger of two exhaust lines. Downstream of the second turbocharger and upstream of the merger is no oxygen-sensitive measuring device required.

is a secondary air supply line necessary in the exhaust, this may preferably only in the first exhaust line be provided. A cheap one Installation position is downstream of the first turbocharger acting Exhaust valves and upstream of the first close-coupled catalyst. This configuration is particularly evident in a longitudinal installation more benefits, there for a quick moment building no short ways to the first and second turbocharger are required. It is appropriate, one exhaust gas supply to keep the first turbocharger as short as possible while the second turbocharger may be further spaced. In the direction of travel Thus, the second turbocharger may be located further back than the first turbocharger, what about longitudinal installation brings significant space advantages.

In a favorable embodiment, the compressors of the turbocharger can be connected in parallel, in particular they convey into the same pressure line. Advantageously, a pressure control device is provided at a junction of compressor-side lines of a suction device, which ensures that a possible different boost pressure of both compressors in particular operation conditions, such as when switching the exhaust valves, causing interference. The pressure control device may be passive, for example, via a pivotable element which, depending on the pressure conditions in the flow direction sets before the merge a same boost pressure, or active via one or two operable via actuators throttle devices, depending on a respective pressure sensor between the compressor and the merge be controlled. Another pressure sensor may be provided downstream of the merge. It is advantageous if the pressure in the compressor-side lines can be regulated to the same desired value.

In a cheap one alternative embodiment can the turbocharger compressors are connected in series with each other the pressure conditions multiply the turbocharger. This achieves a high boost pressure. Preferably, the first turbocharger is switched off at rated power, an overload to avoid the first turbocharger. Conveniently, the exhaust valves Both groups of exhaust valves can be switched off to protect the disconnected first turbocharger whose turbine to keep free of exhaust gas.

The Turbocharger direction according to the invention can be used on both even and odd cylinder engines be provided, as well as also be provided more than just a cylinder head. Preferred are exactly two turbochargers per cylinder head provided. So can also an odd-numbered engine, such as a 5-cylinder engine, an arrangement with two turbochargers can be realized.

Further Embodiments and aspects of the invention will be independent of a summary in the claims without limitation of the Generality explained in more detail below with reference to a drawing. there demonstrate

1 a preferred turbocharger apparatus according to a first embodiment with a 6-cylinder engine with two turbochargers with valve shutdown and an arrangement of oxygen-sensitive measuring devices and a secondary air injection;

2 a preferred turbocharger apparatus according to the first embodiment with longitudinal installation of the turbocharger;

3 a preferred turbocharger apparatus according to the first embodiment with suction device;

4 a preferred pressure control device for the suction in 3 ;

5 a preferred turbocharger device with a 4-cylinder engine;

6 a preferred turbocharger device with a 5-cylinder engine.

1 shows to illustrate the invention, a turbocharger apparatus according to a first embodiment with an engine designed as a 6-cylinder engine 10 whose cylinder 11 two intake valves each 12 and 13 and at least two exhaust valves 14 and 15 exhibit. The internal combustion engine 10 has a cylinder head. In an internal combustion engine 10 with multiple cylinder heads are preferably per cylinder head of the engine 10 two turbochargers 18 and 22 provided, more preferably exactly two turbochargers per cylinder head are provided.

Details of a suction device containing the compressors 19 and 23 supplied, are not shown in this figure. For several similar elements only one is provided with reference numerals. Furthermore, the same reference numerals are used in the various figures of the drawing for the same elements.

The exhaust valves 14 and 15 form two groups of exhaust valves 14 . 15 , The first group of exhaust valves 14 is with a manifold of a first exhaust line 16 and the second group of exhaust valves 15 is with a manifold of a second exhaust line 17 connected. In the first exhaust system 16 is a first turbocharger 18 with a compressor 19 and a turbine 20 arranged. The turbine 20 is from an exhaust gas mass flow of the first group associated exhaust valves 14 pressurizes and drives the compressor 19 at. In the second exhaust system 17 is a second turbocharger 22 with a compressor 23 and a turbine 24 arranged. The turbine 24 is from an exhaust gas mass flow of the second group associated exhaust valves 15 pressurizes and drives the compressor 23 at.

At least part of the second turbocharger 22 acting exhaust valves 15 is designed switchable, preferably all exhaust valves 15 switched off. At low speeds of the internal combustion engine 10 is essentially just the turbine 20 the first turbocharger 18 Exhaust gas flows through from the exhaust valves 14 is charged. The for charging the second turbocharger 22 provided shutdown exhaust valves 15 are gradually activated with increasing exhaust gas mass flow. This can for example via an unillustrated engine control unit respectively. Will any shut off exhaust valve 15 activated individually, this is done in six steps. Be the exhaust valves 15 activated in pairs, are three steps, each will have three exhaust valves 15 are two steps to fully activate all the exhaust valves 15 necessary. A valve lift curve and / or timing of the exhaust valves 14 The first group may differ from those of the exhaust valves 15 be different from the second group.

Each of the cylinders 11 is about his exhaust valves 14 . 15 with both turbochargers 18 and 22 connected. The first turbocharger 18 is preferably designed smaller than the second turbocharger 22 , where the second turbocharger 22 on the rated power of the internal combustion engine 10 is designed. The turbine 24 of the second turbocharger 22 is designed larger than a comparable one-stage charging. The first turbocharger 18 acting exhaust valves 14 are different in diameter, preferably smaller, than the second turbocharger 22 acting exhaust valves 15 ,

Optionally, a secondary air supply line 28 with in each connecting line of the first group of exhaust valves 14 to the manifold of the first exhaust line 16 protruding feeders 29 be provided. In the first exhaust system 16 is a first catalytic converter 25 intended. In the exhaust gas flow direction behind the second turbocharger 22 is a second catalyst 26 after a merge 27 the manifolds of the first and second exhaust line 16 and 17 intended. Upstream of the first catalyst 25 and downstream of the second catalyst 26 in each case an oxygen-sensitive measuring device 41 and 42 intended. The oxygen-sensitive measuring device 41 preferably includes a broadband lambda probe while the oxygen sensing measuring device 42 preferably comprises a lambda probe with step response. It can also be a third oxygen-sensitive measuring device 43 downstream of the first catalyst 25 before or after the merge 27 be provided, in particular before the merger 27 ,

The preferred embodiment in 2 shows an arrangement according to the embodiment of 1 , which is particularly suitable for longitudinal installation, seen from their required small space. Details such as a possibly existing secondary air supply line, a suction device or an exhaust gas sensor system are not shown.

Seen in the direction of travel is the second turbocharger 22 behind the first turbocharger 18 , The exhaust system 16 to the first turbocharger 18 can be made significantly shorter than the second turbocharger 22 whose length of the exhaust line 17 is not critical. The first turbocharger 18 , the first catalyst 25 , the second turbocharger 22 and he second catalyst 26 are arranged sequentially in this order.

3 illustrates a suction device of an arrangement according to the first embodiment. Details such as a possibly existing secondary air supply line or an exhaust gas sensor system are not shown. The compressor 19 the first turbocharger 18 is via a suction line 30 supplied with supply air via a pressure line 31 and a distribution line 38 to the intake valves 12 . 13 is directed. The compressor 23 of the second turbocharger 22 is via a suction line 32 supplied with supply air via a pressure line 33 and a distribution line 38 to the intake valves 12 . 13 is directed. The two pressure lines 31 and 33 lead to a merger 34 into the distribution line 38 that have feeders 36 . 37 the compressed air to the intake valves 12 . 13 the cylinder 11 distributed.

In principle, the compressors 19 and 23 the turbocharger 18 and 22 be connected in series, with the first turbocharger 18 designed to be switched off at rated power. It is expedient, the exhaust valves 14 . 15 the first and the second group can be switched off.

Alternatively, the compressors 19 and 23 the turbocharger 18 and 22 be connected in parallel, taking part in the merge 34 the compressor-side pressure lines 31 and 33 a pressure control device 40 is provided to possible boost pressure differences of the two compressors 19 . 23 compensate. This circuit of the compressor 19 and 23 is preferred. 4 illustrates in a schematic representation of the pressure control device 40 , At the merger 34 is a flap 35 provided, which is continuously movable and active or passive controllable. By partially obstructing the two pressure lines 31 and 32 Both are pressure lines 31 . 32 adjusted to the higher of the two boost pressures, including in each of the pressure lines 31 . 33 in each case a pressure sensor P1 or P2 is provided. In the distribution line 38 Optionally, a third pressure sensor P3 may be provided.

The arrangement in 5 illustrates a preferred turbocharger device according to a second embodiment of an engine designed as a 4-cylinder engine 10 Details of a secondary air supply line or a suction device or an exhaust gas sensor are not shown. Preferably, the internal combustion engine 10 an inline engine or a VR engine. The internal combustion engine 10 has a cylinder head. cylinder 11 the internal combustion engine 10 each have two inlet valves 12 and 13 and at least two exhaust valves 14 and 15 on. In an internal combustion engine 10 with several cylinder heads are preferably per cy Head of the engine 10 two turbochargers 18 and 22 provided, particularly preferred are exactly two turbochargers 18 . 22 provided per cylinder head.

The exhaust valves 14 and 15 form two groups of exhaust valves 14 . 15 , The first group of exhaust valves 14 is with a manifold of a first exhaust line 16 and the second group of exhaust valves 15 is with a manifold of a second exhaust line 17 connected. In the first exhaust system 16 is a first turbocharger 18 with a compressor 19 and a turbine 20 arranged. The turbine 20 is from an exhaust gas mass flow of the first group associated exhaust valves 14 pressurizes and drives the compressor 19 at. In the second exhaust system 17 is a second turbocharger 22 with a compressor 23 and a turbine 24 arranged. The turbine 24 is from an exhaust gas mass flow of the second group associated exhaust valves 15 pressurizes and drives the compressor 23 at.

At least part of the second turbocharger 22 acting exhaust valves 15 , preferably all, is designed to be switched off. At low speeds of the internal combustion engine 10 is essentially just the turbine 20 the first turbocharger 18 flows through exhaust gas. The for charging the second turbocharger 22 provided shutdown exhaust valves 15 are gradually activated with increasing exhaust gas mass flow. This can be done for example via an unillustrated engine control unit. Will any shut off exhaust valve 15 activated individually, this is done in four steps. Be the exhaust valves 15 activated in pairs, two steps are necessary.

The features and variants mentioned for the first embodiment apply here accordingly. Furthermore, the statements apply mutatis mutandis to internal combustion engines 10 with an 8-cylinder engine with two cylinder heads and accordingly 4 turbochargers 18 . 22 and 16-cylinder engines with two or four cylinder heads and four or eight turbochargers 18 . 22 ,

How out 6 can be seen, according to a third embodiment, a preferred exhaust valve related turbocharger device with two turbochargers 18 . 22 also for an internal combustion engine 10 be used with odd number of cylinders and a single cylinder head.

In the exemplary embodiment, the internal combustion engine is designed as a 5-cylinder engine. cylinder 11 the internal combustion engine 10 each have two inlet valves 12 and 13 and at least two exhaust valves 14 and 15 on. Details of a secondary air supply line and / or an intake device and / or an exhaust gas sensor system are not shown. In an internal combustion engine 10 with multiple cylinder heads are preferably per cylinder head of the engine 10 two turbochargers 18 and 22 provided, more preferably exactly two turbochargers per cylinder head are provided.

The exhaust valves 14 and 15 form two groups of exhaust valves 14 . 15 , The first group of exhaust valves 14 is with a manifold of a first exhaust line 16 and the second group of exhaust valves 15 is with a manifold of a second exhaust line 17 connected. In the first exhaust system 16 is a first turbocharger 18 with a compressor 19 and a turbine 20 arranged. The turbine 20 is from an exhaust gas mass flow of the first group associated exhaust valves 14 pressurizes and drives the compressor 19 at. In the second exhaust system 17 is a second turbocharger 22 with a compressor 23 and a turbine 24 arranged. The turbine 24 is from an exhaust gas mass flow of the second group associated exhaust valves 15 pressurizes and drives the compressor 23 at.

The for the first and second embodiments mentioned features and variants apply here accordingly.

Claims (30)

Internal combustion engine ( 10 ) with a turbocharger device having at least a first and a second turbocharger ( 18 . 22 ), whose compressor ( 19 . 23 ) of exhaust gas turbines ( 20 . 24 ) are drivable, wherein the first turbocharger ( 18 ) in a first exhaust gas line ( 16 ) of a first group of exhaust valves ( 14 ) of the internal combustion engine ( 10 ) and a second turbocharger ( 22 ) in a second exhaust line ( 17 ) of a second group of exhaust valves ( 15 ), characterized in that at least a part of the cylinders ( 11 ) on the exhaust side with both turbochargers ( 18 . 22 ) connected is. Internal combustion engine according to claim 1, characterized by a spark igniting Embodiment, in particular a direct-injection design. Internal combustion engine according to claim 1 or 2, characterized in that the first turbocharger ( 18 ) is smaller than the second turbocharger ( 22 ). Internal combustion engine according to claim 3, characterized in that the second turbocharger ( 22 ) to the rated power of the internal combustion engine ( 10 ) is designed. Internal combustion engine according to at least one of the preceding claims, characterized in that the turbine ( 24 ) of the second turbocharger ( 22 ) is designed larger than a single-stage charge. Internal combustion engine according to at least one of the preceding claims, characterized in that at least a part of the second turbocharger ( 22 ) acting exhaust valves ( 15 ) can be reduced in flow, in particular switched off, is formed. Internal combustion engine according to claim 6, characterized in that the part of the second turbocharger acting exhaust valves ( 15 ) is designed to be switched off. Internal combustion engine according to at least one of the preceding claims, characterized in that the first turbocharger ( 18 ) acting exhaust valves ( 14 ) in diameter different from the second turbocharger ( 22 ) acting exhaust valves ( 15 ) are formed. Internal combustion engine according to claim 8, characterized in that the first turbocharger ( 18 ) acting exhaust valves ( 14 ) smaller in diameter than the second turbocharger ( 22 ) acting exhaust valves ( 15 ) are formed. Internal combustion engine according to at least one of the preceding claims, characterized in that a valve lift and / or control times of the exhaust valves ( 14 ) of the first group of a valve lift and / or timing of the exhaust valves ( 15 ) of the second group are different. Internal combustion engine according to at least one of the preceding claims, characterized in that for acting on the second turbocharger ( 22 ) provided shutdown exhaust valves ( 15 ) are gradually activated with increasing exhaust gas mass flow. Internal combustion engine according to claim 11, characterized in that that activation in an N-cylinder engine in N / m increments where m is an integer of 1≤m≤N. Internal combustion engine according to at least one of the preceding claims, characterized in that per cylinder head two turbochargers ( 18 . 22 ) are provided. Internal combustion engine according to claim 13, characterized in that one of the turbochargers ( 18 . 22 ) is designed without bypass valve. Internal combustion engine according to claim 14, characterized in that the first turbocharger ( 18 ) is designed without bypass valve. Internal combustion engine according to at least one of the preceding claims, characterized in that in the first exhaust gas line ( 16 ) a first catalytic converter ( 25 ) is provided. Internal combustion engine according to claim 16, characterized in that the first catalytic converter ( 25 ) upstream of the turbocharger ( 18 ) is provided. Internal combustion engine according to claim 16, characterized in that the first catalytic converter ( 25 ) downstream of the turbocharger ( 18 ) is provided. Internal combustion engine according to at least one of the preceding claims, characterized in that in the exhaust gas flow direction behind the second turbocharger ( 22 ) a second catalyst ( 26 ) after a merge ( 27 ) of the first and the second exhaust line ( 16 . 17 ) is provided. Internal combustion engine according to claim 20, characterized in that the second catalyst ( 26 ) in volume greater than the first catalyst ( 25 ) is trained. Internal combustion engine according to at least one of the preceding claims, characterized in that upstream of the first catalyst ( 25 ) and downstream of the second catalyst ( 26 ) each an oxygen-sensitive measuring device ( 41 . 42 ) is provided. Internal combustion engine according to claim 21, characterized in that a third oxygen-sensitive measuring device ( 43 ) upstream of the second catalyst ( 26 ) is provided. Internal combustion engine according to claim 22, characterized in that the third oxygen-sensitive measuring device ( 43 ) downstream of the merge ( 27 ) is provided. Internal combustion engine according to at least one of the preceding claims, characterized in that a secondary air supply line ( 28 ) only in the first exhaust gas line ( 16 ) is provided. Internal combustion engine according to at least one of the preceding claims, characterized in that the compressors ( 19 . 23 ) the turbocharger ( 18 . 22 ) are connected in parallel fluidically. Internal combustion engine according to claim 25, since characterized in that between compressor-side lines ( 31 . 33 ) for supplying air to intake valves ( 12 . 13 ) the cylinder ( 11 ) a pressure control device ( 40 ) is provided. Internal combustion engine according to claim 26, characterized in that the pressure in the compressor-side lines ( 31 . 33 ) can be adjusted to the same desired value. Internal combustion engine according to at least one of claims 1 to 24, characterized in that the compressors ( 19 . 23 ) the turbocharger ( 18 . 22 ) are connected in series. Internal combustion engine according to claim 28, characterized in that the first turbocharger ( 18 ) can be switched off at nominal power. Internal combustion engine according to claim 28 or 29, characterized in that the exhaust valves ( 14 . 15 ) can be switched off.