SE1550789A1 - Turbocharged internal combustion engine - Google Patents

Abstract

An engine is divided into two cylinder groups. Branch lines from the cylinders of one group are connected to a first inlet channel (11) and branch lines from the cylinders of the other group are connected to a second inlet channel (14). The respective inlet duct (11,14) is connected to an inlet opening (23,24) on a twin entry turbine having a turbine housing (22) with a separate inlet (23,24) to each of two separate ducts (25 , 26) extending into the turbine housing (22) in which a turbine wheel (12) is mounted. A sealing device (50) is arranged between the inlets (23, 24) to counteract crosstalk between the inlet channels (11, 14). (Fig. 2)

Description

FIELD OF THE INVENTION The present invention relates to a turbocharged internal combustion engine and a vehicle comprising a turbocharged internal combustion engine according to the appended claims.

BACKGROUND AND PRIOR ART Exhaust gases from multi-cylinder internal combustion engines are usually received in a manifold, which includes branch lines which receive exhaust gases from the engine cylinders and a main line which receives the exhaust gases from the respective branch line. Exhaust gases flow through the main line to a turbocharger to increase the fuel efficiency and power of the engine by forcing additional air into the combustion chambers. The turbocharger usually includes a turbine that is powered by the exhaust gases and a compressor that compresses air that is led to the engine.

When the exhaust valves in a cylinder open, the exhaust gases initially flow out of the branch line with a high pressure which is essentially related to the exhaust gas pressure in the cylinder after the combustion rate has just ended. The pressure of the exhaust gases in the manifold during the remaining part of the time that the exhaust valves are open is lower and essentially related to the work that the piston performs when the exhaust gases in the manifold push out from the cylinder. The exhaust valves in a single cylinder are normally open during the entire exhaust rate, ie. during a relatively large part of a four-stroke engine's work cycle. In multi-cylinder internal combustion engines it is common for the opening times of the exhaust valves in different cylinders to overlap. The overlap varies depending on the number of cylinders and ignition order and can result in a cylinder being emptied at the same time as the adjacent cylinder is at the end of its opening time.

When the exhaust valves in a cylinder open, the exhaust gases are thus led out of the cylinder with a high pressure in the connected branch line and the main line. If exhaust gases are simultaneously led out of another cylinder in another branch line with a lower pressure, there is an obvious risk that the exhaust gases with that right pressure penetrate in the branch line with the lower exhaust pressure, which is called crosstalk. Thus, the pressure in this branch line rises and an increased pumping action of the piston in the cylinder is required to feed the exhaust gases. The increased pumping work results in an increased fuel consumption in the internal combustion engine. In addition, an increased amount of residual gases is obtained in the cylinder, which affects temperature and combustion in a negative way.

It is known to counteract crosstalk by dividing the engine on the exhaust side into two cylinder groups, the branch lines from the cylinders of that one group being joined to a first main line and the branch lines from the second group of cylinders being joined to another main line. The respective main line is connected to an inlet on the turbine of so-called twin scroll or twin entry type which has a turbine housing with a separate inlet to each of two different channels extending into the turbine housing in which a turbine wheel is stored.

By separating the exhaust gases from each other, the risk of crosstalk is reduced and a more evenly distributed gas exchange is obtained. The division results in that compression waves on the exhaust side cannot be transferred to other cylinders and affect the gas exchange.

A problem with known solutions is that crosstalk pressure pulses can occur between the first main line and the second main line at the inlet to the turbine where the two main lines are separated from each other by only one partition and connected to corresponding channels in the turbine housing, which channels are also separated from each other by only one partition wall. The two partition walls extend towards each other, but in order for it to be possible for them to grow due to thermal expansion under load, a gap or a clearance is formed between the end portions of the partition walls. The gap allows for thermal expansion but at the same time creates crosstalk problems because pressure pulses can pass through the gap.

Another problem is that the partitions grow over time due to oxidation and other effects, which means that the gap decreases. This results in the fact that the crosstalk can decrease but that the partitions instead risk colliding with each other when they grow due to thermal expansion, which can lead to cracking and rock strength problems.

Another problem is that it can be difficult to mount the trunk against the turbine housing so that the partition wall between the respective trunk is positioned in the middle of the corresponding partition wall in the turbine housing. This can result in increased crosstalk.

SUMMARY OF THE INVENTION An object of the present invention is to counteract crosstalk intermediate trunk lines at the inlet of a turbine. Another object is to prevent partitions from colliding with each other as they grow due to thermal expansion, thereby reducing the risk of cracking and second strength problems.

These objects are achieved by a sealing device as defined in the dependent claims.

By using the sealing device according to the invention, crosstalk of pressure pulses between the lines is counteracted, which results in short-circuit pressure pulses not interfering with the gas exchange work in the engine during the emptying phase of the respective cylinder, which in turn results in less residual gases in the cylinder.

Since crosstalk of pressure pulses is counteracted, more pulse energy passes the turbine, which leads to better efficiency of the turbine, higher available turbine power and thus also to higher boost pressure and higher engine torque at low speeds.

By utilizing the sealing device, it also reduces the stress that can occur when the respective partition wall grows in length due to thermal expansion, which means that the risk of e.g. cracking decreases.

In an advantageous embodiment, the first sealing portion consists of a depression in the end portion of one partition wall and the second sealing portion of a projecting portion in the end portion of the second partition wall, which projecting portion is adapted to project into the depression. Since one sealing portion projects into the other sealing portion and delimits a gap, which is advantageously U-shaped, a labyrinth seal is obtained which effectively prevents crosstalk at the same time as the gap enables thermal expansion of the partitions.

In a further advantageous embodiment, the first sealing portion is arranged at the partition wall which separates the groups from each other and the second sealing portion at the partition wall which separates the channels from each other. Sealing effect is achieved by pressure pulses entering the labyrinth and attenuated by being redirected. the labyrinth significantly weaker than they were at the entrance. By arranging the sealing portions in the advantageous manner, more deflections are obtained and therefore also a more effective seal.

In a further advantageous embodiment, a flange joint is arranged around the end portions of the two partitions, which flange joint is formed with a centering arrangement to ensure during assembly that the first sealing portion and the second sealing portion are positioned opposite each other. This results in a better location of the two relative sealing portions. a simplified assembly and an efficient function of the sealing arrangement.

In a further advantageous embodiment, the centering arrangement comprises a projecting part adapted in a first flange adapted to project into a corresponding depression formed in a second flange. This provides an efficient and reliable location of the two sealing portions relative to each other.

Other features and advantages of the invention will be apparent from the claims, the description of embodiments and the accompanying figures.

BRIEF DESCRIPTION OF THE DRAWINGS In the following, exemplary embodiments of the invention are described with reference to the accompanying drawings, in which: Fig. 1 schematically shows a vehicle driven by an overcharged internal combustion engine.

Fig. 2 shows a section through a turbocharger shown in Fig. 1.

Fig. 3a shows a cross section along a line A in Fig. 2 seen in direction B.

Fig. 3b shows a cross section along a line A in Fig. 2 seen in direction C.

Fig. 4 schematically shows a first embodiment of the invention sealing device.

Fig. 5 shows a perspective view with broken away parts of a second embodiment of the sealing device according to the invention.

DETAILED DESCRIPTION OF EMBODIMENT FORVIVES OF THE INVENTION Fig. 1 schematically shows a vehicle 1 driven by a supercharged internal combustion engine 2. The vehicle 1 is advantageously a heavy vehicle and the internal combustion engine 2 may be a diesel engine or an otto engine. In alternative embodiments, the internal combustion engine may be intended for industrial or marine use. The combustion engine 2 is in this case exemplified as a straight six-cylinder engine with a first manifold 3 which receives exhaust gases from three cylinders 4,5,6 via a branch line 4a, 5a, 6a from each cylinder 4,5,6 and a second manifold 7 which receives exhaust gases from three cylinders 8,9,10 via single branch line 8a, 9a, 10a from each cylinder 8,9,10. Exhaust gases from the first manifold 3 of the internal combustion engine 2 are led via a first main line which is further referred to as the first inlet duct 11 to a turbine 12 of a second turbocharger 13. Exhaust gases from the second manifold 7 of the internal combustion engine 2 are routed via a second trunk line. 8a, 9a, 10a are thus brought together in two groups. In the following description, the first inlet duct 11 represents one group and the other inlet duct 14 the other group.

The exhaust gases leaving the internal combustion engine 2 have an overpressure which results in them expanding through the turbine 12. The turbine 12 thereby obtains a driving force which is transmitted via a connection to a compressor 15 of the turbocharger 13. The compressor 15 thereby compresses air which is sucked into an inlet line 17 via an air filter 16. The compressed air in the inlet line 17 is cooled in a single-charge air cooler 18 before it is led to the internal combustion engine 2.

By directing exhaust gases from the combustion engine 2 and manifolds 3, 77 via separate inlet ducts 11, 14 to the turbine 12, a substantially uniform exhaust gas pressure can be maintained acting on the turbine 12. Thus a high volumetric efficiency can be maintained as the exhaust gases expand through the turbine. the inlet ducts 11,14 extend through a common transition portion 20 arranged between respective branch pipes 3,7 shown in Fig. 1 and the turbine 12 shown in Fig. 2 and are separated from each other by a first partition 21. The transition portion 20 is connected to a turbine housing 22. The connection can, as shown in Fig. 4, be designed as a conventional flange joint 42 where two flanges 43,47 are pressed against each other with screw joints (not shown). The flanges 43,47 can be circular or have another arbitrary appearance, e.g. rectangular, depending on the application in which they are arranged. Alternatively, the flanges 43,47 can be pressed against each other in another suitable manner.ex. with a screw-attachable clamp or a strap, e.g. a V-shaped band, which encloses the flanges 43,47 and presses them against each other. Fig. 2 shows that the turbine housing 22 is formed with two inlet openings 23,24, one center for each inlet duct 11,14. Each inlet opening 23,24 connects to a single channel 25,26 which is connected to a turbine chamber 27 in which the turbine 12 is arranged. The channels 25, 26 are then separated from each other by a second partition wall 28 which is positioned in front of and in line with the partition wall 21 of the transition portion 20.

The manifolds 3.7 which may also be called exhaust collectors, the transition portion 20, the turbine housing 22 and the partitions 21,28 may be made of any material which has the right properties in terms of material strength and resistance to the environment in which they are located but preferably they are made of steel, cast iron or composite material. In addition, the manifolds 3,7 may be made of sheet metal, preferably steel sheet. At least one duct 25,26 but in this exemplary embodiment the bed ducts 25,26 are connected to a bypass passage 31 through which the exhaust gas can be led to an exhaust duct 32 which is located downstream of the turbine 12 and further out through an exhaust outlet 33 without passing through the turbine 12 where it risks overloaded. The ducts 25,26 can be opened and closed in a conventional manner by means of a wastegate valve 34 as control-oriented control lines 35 from a control unit (not shown). At least one duct 25,26 but in this exemplary embodiment the bath ducts 25,26 are furthermore connected to a passage 38 which houses an EGR valve 39 and which via an outlet opening 37 connects the exhaust gas recirculation system 2 of the combustion engine 2. The EGR valves 39 are controlled in a conventional manner from a control unit (not shown) for recirculating a part of the exhaust gases to the inlet line 17 downstream of the charge air cooler 18 shown in Fig. 1. In Figs. 3a and 3b a cross section between the transition portion 20 and the turbine housing 22 is shown along a line A in Fig. 2. Fig. 3a shows the cross section seen in a direction B and fig.3b shows the cross section seen in a direction C.

Figs. 3a and 3b show that the transition portion 20 comprises a circular flange 43 with a number of through holes 44 for screw connections (not shown) intended to connect the flange 43 with a corresponding flange 47 with a through heel 48 to the turbine housing 22. The first inlet channel 11 and the second inlet channel 14 have a D -shaped cross-sectional shape and are separated from each other by the partition wall 21. The channels 25, 26 of the turbine housing also have a D-shaped cross-sectional shape and are separated from each other by a partition wall 28. Through the heel 44,48, the channels 11,14 and 25,26 and the partitions 21, 28 are positioned opposite each other after assembly.

The channels 11,14,25,26 do not have to have a D-shaped cross-sectional shape, but they can be designed in a number of different ways. The channels 11,14,25,26 hart.ex. shown in Fig. 5. a substantially rectangular cross-sectional shape but the cross-sectional shape may also be square, circular, oval or have any other shape suitable for the application in question.

A sealing means, preferably in the form of a gasket 45, can, as shown in Figs. 3a and 3b, be arranged between the flanges 43,47 if it is necessary to prevent exhaust gases from leaking out. The gasket is suitably made of metal, preferably of steel and advantageously consists of one or more sheet layers punched in a continuous piece. If several plate layers are used, these are stacked on top of each other and compressed into a gasket.

In order to counteract the crosstalk between the inlet channels 11, 14 shown in Fig. 2 at the inlet openings 23,24 to the turbine housing 22, a sealing device 50 is arranged at the partition walls 21,28. Fig. 2 shows the location of the sealing device 50 and in Figs. 3a and 3b it is shown that the sealing device 50 comprises a first sealing portion 51 arranged at an end portion 52 of the transition wall 21 of the transition portion 20 and a second sealing portion 53 arranged at an end portion 54 of the end wall 28 of the host turbine housing 52. , 53 are adapted to be directed towards each other. The two sealing portions 51,54 can in one alternative embodiment change places with each other so that the first sealing portion 51 is arranged at an end portion 54 of the intermediate wall 28 of the turbine housing 22 and the second sealing portion 53 is arranged at an end portion 52 of the transition portion 20 partition wall 21.

The first sealing portion 51 consists of an elongate recess which extends along substantially the entire length of the end portion 52. The second sealing portion 53 is constituted by an elongate projecting portion which extends along the length of substantially the entire end portion 54. The first sealing portion 51 and the second sealing portion 53 are adapted to sealingly co-operate with each other and thereby form a seal, preferably a labyrinth seal, which is shown in Figs. 4 and 5. In Figs. 4 and 5 the area between the transition portion 20 and the turbine housing 22 is shown. 53 which is constituted by the projecting portion is arranged to project into the first sealing portion 51 which is constituted by the recess. The bath seal portions thereby define a U-shaped gap 55. Since the single seal portion projects into the second seal portion and defines a gap 55, a labyrinth seal is obtained which effectively prevents crosstalk of the pressure pulse between the conduits 11,14 resulting in short-circuiting compression. during the emptying phase of the respective cylinder, which in turn results in less residual gases in the cylinder and that the air supply to the engine is improved. Since crosstalk of pressure pulses is counteracted, essentially all pressure pulses are controlled through the turbine via the channels 25,26, which leads to better efficiency of the turbine, higher available turbine power and thus also to higher boost pressures and higher engine torque pile speeds. The gap 55 also creates a clearance that enables thermal expansion of the partitions 21,28 without these risking colliding with each other, which results in the risk of e.g. cracking in the partitions21,28 decreases.

The second sealing portion 53, i.e. the height of the projecting portion is less than 10 mm but preferably 3-5 mm and its width is less than 10 mm but preferably 3-5 mm. The width of the gap, ie. the distance between the protruding portion and the walls of the recess is less than 3 mm but preferably 1-1.5 mm. The first sealing portion 51, i.e. the depth of the depression is less than 13 mm but preferably 4-6.5 mm. In an advantageous embodiment, the height of the projecting portion is 5 mm, its width 3 mm and the width of the gap 1.5 mm.

In order to ensure during assembly that the first sealing portion 51 and the second sealing portion 53 are positioned opposite each other, the flange joint 42 comprises a centering arrangement 46. One flange 43, 47 is then formed with a projecting part 57 adapted to slide into a corresponding recess 58 in the second flange 43. , 47.

During operation of the vehicle, exhaust gases flow through the two inlet lines 11,14, through the inlet openings 23,24 and the ducts 25,26 to the turbine chamber. The sealing device 50 is arranged between the partitions 21,28 to prevent truck pulses from being transmitted from one inlet line 11,14 to the other inlet line 11,14. The sealing effect is achieved by pressure pulses entering the gap 55 and being attenuated by the choke cells being redirected a number of times in the gap 55 before it exits the gap 55 much weaker than they were at the entrance. The invention is not limited to the described embodiments, but a multitude of possibilities for modifications thereof are obvious to the person skilled in the art without departing from the basic idea of the invention as defined in the claims.

The number of cylinders which connect to a main line via manifolds can vary and in its simplest form the engine has only two cylinders which connect to a single main line, but the invention can of course be applied to motors with a different number of cylinders, e.g. four, five, six or eight without losing the idea of invention.

Claims (2)

1. Turbocharged internal combustion engine (2) with at least two cylinders (4,5,6,8,9,10) and a manifold (3,7) having a manifold (4a, 5a, 6a, 8a, 9a, 10a) from each cylinder (4,5,6,8,9,10), the manifolds (4a, 5a, 6a, 8a, 9a, 10a) being joined in at least two groups (11,14) opening into each inlet (23, 24) to separate ducts (25,26) which each open into a turbine housing (22), the groups (11,14) being separated from each other by a first partition wall (21) and the ducts (25,26) being separated from each other with a second partition wall (28) which partition walls (21, 28) have end portions (51, 54) directed towards each other, characterized in that a sealing device (50) extends the end portions (51, 54) of the partition walls (21, 28) which sealing device (50) comprises a first sealing portion (51) and a second sealing portion (53) adapted to sealingly cooperate with each other and delimit a gap (55). Turbocharged internal combustion engine according to claim 1, characterized in that the first sealing portion (51) is arranged at the end portion (52, 54) of one partition (21, 28) and the second sealing portion (53) is provided at the end portion (21, 28) of the second partition (21, 28). 52.54). Turbocharged internal combustion engine according to claim 2, characterized in that the first sealing portion (51) consists of a recess in the end portion (52, 28) of the intermediate wall (21, 28) and the second sealing portion (53) of a projecting portion of the second partition (21, 28). ) end portion (52.54) which protruding portion is adapted to slide into the recess. Turbocharged internal combustion engine according to one of the preceding claims, characterized in that the first sealing portion (51) and the second sealing portion (53) delimit a U-shaped gap (55). Turbocharged internal combustion engine according to any one of the preceding claims, characterized in that the first sealing portion (51) is arranged next to the partition wall (21) separating the groups (11, 14) from each other and the second sealing portion (53) at the partition wall (28) separating the channels (25,26) apart. Turbocharged internal combustion engine according to one of the preceding claims, characterized in that a flange joint (52) is arranged around the end portions (52, 28) of the bathroom partitions (21, 28), which flange joint (52) is formed with a centering arrangement (46) to ensure that during assembly the first sealing portion (51) and the second sealing portion (53) are positioned opposite each other. Turbocharged internal combustion engine according to claim 6, characterized in that the centering arrangement (46) comprises a projecting part (57) formed in a first flange (43,47) adapted to project into a corresponding recess (58) formed in a second flange (43,47). Turbocharged internal combustion engine according to one of Claims 1 to 6, characterized in that the height of the second sealing portion (53) is less than 10 mm, but preferably 3-5 mm. Turbocharged internal combustion engine according to one of Claims 1 to 6, characterized in that the width of the second sealing portion (53) is less than 10 mm, but preferably 3-5 mm. Turbocharged internal combustion engine according to one of Claims 1 to 6, characterized in that the depth of the first sealing portion (51) is less than 13 mm, but preferably 4-6.5 mm. Turbocharged internal combustion engine according to Claim 1 or 4, characterized in that the width of the gap (55) is less than 3 mm but preferably 1-1.5 mm. A vehicle (1) comprising a turbocharged internal combustion engine according to any one of claims 1-11.