Turbocharged Engine Assembly With Two Exhaust Pipes And Regulating Valve

Abstract

The invention relates to an engine assembly (1) comprising a turbine (2) and an exhaust system removing the gasses from the engine and comprising a first pipe (4) leading from a first manifold (5) and a second discharge pipe (6) leading from a second manifold (7), the turbine (2) comprising a casing (2c) surrounding it and an energy-recovering impeller, the first pipe (4) opening into a main expansion passage housing the impeller. The second pipe (6) opens into at least one bypass portion (8) internal to the casing (2c) and bypassing the main expansion passage, the main expansion passage and said at least one bypass portion (8) meeting at an outlet face (2b) of the casing (2c), the main expansion passage comprising, inside the turbine (2), a valve for regulating the flow of exhaust gas passing through it.

Claims

1. An engine assembly comprising an internal combustion engine with at least one cylinder, a turbocharger comprising a turbine and a compressor, and an exhaust system connected to an engine outlet in order to remove the exhaust gases resulting from the combustion in the engine, the exhaust system comprising a first so-called exhaust duct through the turbine leading from a first exhaust manifold and a second so-called discharge duct leading from a second exhaust manifold, the turbine being provided with a casing having a main expansion passage in which is housed a turbine impeller and the first duct opening into the main expansion passage through an inlet face of the casing, characterized in that the second duct opens through the inlet face of the casing into at least one bypass portion inside the casing bypassing the main expansion passage, the main expansion passage and said at least one bypass portion joining at an outlet face of the casing, the main expansion passage comprising, inside the turbine, a valve for regulating the flow of exhaust gas passing through it.

2. The assembly according to claim 1, wherein the exhaust gas flow regulation valve can be controlled in order to regulate the total flow of gas within the entire range from 0% to 100%.

3. The assembly according to claim 1, wherein the exhaust system comprises a third duct outside the turbine and linked to the outlet face of the turbine casing in order to remove the exhaust gases from the turbine.

4. The assembly according to claim 1, wherein the regulation valve is provided with an actuator moving it between at least one first position of closing the main expansion passage with a zero flow in the main expansion passage and one second position of complete opening of the main expansion passage with a maximum flow in the main expansion passage.

5. The assembly according to claim 4, wherein the actuator moves the regulation valve into intermediate opening positions corresponding to different flows in the main expansion passage depending on the degree of opening corresponding to each respective intermediate position.

6. The assembly according claim 4, wherein the regulation valve is in the form of a disk that can be moved in translation or rotation by the actuator.

7. The assembly according to claim 1, wherein the regulation valve is arranged on at least one outlet end of the main expansion passage on the outlet face of the turbine.

8. The assembly according to any claim 1, wherein the exhaust system comprises, downstream of the turbine, decontamination elements for the exhaust gases passing through it.

9. A method of heating up the decontamination elements in an engine assembly according to the claim 8, wherein, since the decontamination elements need to be heated in order to reach a predetermined minimum temperature to ensure the decontamination treatment, the regulation valve of the main expansion passage keeps the exhaust gas flow in the main expansion passage at a zero or reduced value until said minimum temperature is reached.

10. The method according to claim 9, wherein a suspensive condition for keeping the flow of exhaust gas in the main expansion passage at a zero or reduced value is that the pressure at the engine's air intake is higher than atmospheric pressure.

11. A motor vehicle wherein it comprises the assembly according to claim 1.

Description

DESCRIPTION OF THE DRAWINGS

[0045] Further features, aims and advantages of the present invention will emerge from the following detailed description and with regard to the accompanying drawings, given purely by way of non-limiting examples, in which:

[0046] FIG. 1 is a schematic representation of a valve event modulated boost engine assembly comprising an exhaust system with two exhaust ducts based on the closest state of the art,

[0047] FIG. 2 is a schematic representation of an engine assembly comprising an exhaust system with two exhaust ducts according to an embodiment of the present invention, the turbine being passed through by both ducts,

[0048] FIG. 3 is a schematic representation of a longitudinal section of a turbocharger, the turbine of the compressor forming part of an exhaust system of an engine assembly according to the present invention and FIG. 3a shows an embodiment of the inlet face of the turbine,

[0049] FIG. 4 is a schematic representation in perspective of another embodiment of a turbine provided with a casing, this turbine forming part of the exhaust system of the engine assembly according to the present invention and incorporating a regulation valve,

[0050] FIGS. 5 and 5a are schematic representations of a view of the outlet face of a turbine provided with a regulation valve according to FIG. 4, the regulation valve being shown in these Figures in the closed position and in the open position respectively, this turbine forming part of the exhaust system of the engine assembly according to the present invention,

[0051] FIG. 6 is a schematic representation in perspective of another embodiment of a turbine provided with a casing, this turbine forming part of the exhaust system of the engine assembly according to the present invention and incorporating a regulation valve,

[0052] FIGS. 7 and 7a are schematic representations of a view of the outlet face of a turbine provided with a regulation valve according to FIG. 6, the regulation valve being shown in the closed position and in the open position respectively in these Figures, this turbine forming part of the exhaust system according to the present invention.

[0053] It should be borne in mind that the Figures are given by way of example and are non-limiting as regards the invention. They constitute schematic representations of principle intended to facilitate an understanding of the invention and are not necessarily to the scale of practical applications. In particular, the dimensions of the different elements shown are not representative of reality.

DETAILED DESCRIPTION

[0054] FIG. 1 has already been described in the introductory part of this patent application.

[0055] In what follows, the words downstream and upstream are to be understood in relation to the direction of flow of the exhaust gases out of the engine or back towards the engine intake for the recirculation line, an element in the exhaust system downstream of the engine being further away from the engine than another element located upstream of the element. That which is called the engine assembly comprises the combustion engine as well as its auxiliaries for the intake of air into the engine and for the exhaust of gases out of the engine, a turbocharger also forming part of the engine assembly, the turbine being included in the exhaust system of the engine assembly.

[0056] With reference to all of the Figures except for FIG. 1 and particularly to FIG. 2, an engine assembly according to the present invention is shown that includes certain characteristics of an engine assembly of the closest state of the art.

[0057] The engine assembly comprises an internal combustion engine with at least one cylinder and a turbocharger comprising a turbine 2 and a compressor 3. The turbine 2 comprises an impeller recovering at least partially the kinetic energy of the exhaust gases passing through it and transmits this energy to the compressor 3.

[0058] For this purpose, the turbocharger is provided with a shaft linking the impeller of the turbine 2 to an impeller located in the compressor 3, this organ ensuring the compression of the air passing through the compressor 3. This shaft can be lubricated, cooled by water and/or oil and mounted on bearings with or without rollers. This shaft can also be provided with an electrical assistance, either directly on the shaft or with the aid of gears, for example a transmission or a gearbox.

[0059] The exhaust system is connected to an engine outlet in order to remove the exhaust gases resulting from the combustion in the engine and comprises a first so-called exhaust duct 4 through the turbine 2 leading from a first exhaust manifold 5 and a second so-called discharge duct 6 leading from a second exhaust manifold 7. The first and second manifolds 5, 7 are linked to the outlet of the internal combustion engine in order to channel the exhaust gases through the first and second ducts 4, 6. The engine cylinder or each engine cylinder can have at its outlet two outlet passages closed by a respective exhaust valve but this is not compulsory.

[0060] The two exhaust manifolds 5, 7 can be positioned close together in order to be connected to the turbine 2, for example by a flange on the exhaust manifold connecting with a flange provided on a casing 2c of the turbine 2, the casing 2c being particularly visible in FIGS. 3 and 6. The exhaust manifolds 5, 7 can be cooled by a cooling fluid, specifically water, the liquid circulating in a cooling circuit being common or not common to both manifolds 5, 7. The cooling circuit or circuits can also serve to cool the inside of the turbine 2.

[0061] Downstream of the turbine 2, in a known way, a third exhaust duct 9 outside the turbine is provided with decontamination elements 10 that should be brought to and kept at a minimum operating temperature.

[0062] With regard specifically to FIGS. 2, 3, 4 and 6, the turbine 2 of the turbocharger is incorporated in a casing 2c having at least one inlet face 2a for the exhaust gases of the first and second manifolds 4, 6 penetrating into the turbine 2 and one outlet face 2b for the exhaust gases leaving the turbine 2. The turbine 2 has a main expansion passage 4 in which is housed a turbine impeller and the first duct 4 opens into the main expansion passage 4 through the inlet face 2a of the casing 2c. The main expansion passage 4 is particularly visible in FIGS. 3, 4 and 6.

[0063] Thus, according to the present invention, the second duct 6 opens through the inlet face 2a of the casing 2c into at least one bypass portion 8 inside the casing 2c bypassing the main expansion passage 4, the main expansion passage 4 and said at least one bypass portion 8 joining at an outlet face 2b of the casing 2c, the main expansion passage 4 comprising, inside the turbine 2, a regulation valve 13 of the flow of exhaust gas passing through it.

[0064] Thus, a bypass portion 8 extending the second duct 6 is incorporated into the turbine 2 but does not exchange kinetic energy with the impeller of the turbine 2, which has a more efficient discharge effect on the turbine 2 than the discharge effect achieved with a discharge valve. Lastly, the stronger the flow in the second duct 6 compared to the flow in the first duct 4, the hotter the exhaust gases leaving the turbine 2, which reduces the time required to increase the temperature of the decontamination elements 10 located downstream of the turbine.

[0065] The regulation valve 13 advantageously allows the flow in the main expansion passage 4 extending the first so-called exhaust duct 4 in the turbine 2 to be reduced and/or stopped and thus the temperature of the gases after the joining of the extensions of the first and second ducts 4,6 in the turbine, that are the main expansion passage 4 and said at least one bypass portion respectively, to be increased. Passing the respective extensions 4, 8 of the two exhaust ducts 4, 6 through the turbine 2 also ensures better heat insulation of the second duct 6 than in the state of the art. The shortening of the second duct 6 achieved by passing through the turbine 2 helps to reduce loss of heat from the gases passing through the second duct 6.

[0066] A secondary advantage of the exhaust system of the engine assembly 1 according to the present invention, due to the fact that a bypass portion 8 extending the second duct 6 is incorporated into the turbine 2, is to reduce the space occupied by the exhaust system and reduce the cost of material for the second duct 6, the joining of the extension of the first and second ducts 4, 6 taking place in the turbine 2 and not after the turbine 2, resulting in a shortening of the length of the second duct 6 which need not be of a length enabling it to bypass the turbine 2.

[0067] The main expansion passage 4 and said at least one bypass portion 8 extending the first and second ducts 4, 6 respectively can open out at the same level of the turbine 2 on the outlet face 2b of the casing 2c. The exhaust system can comprise a third duct 9 outside the turbine 2 and linked to the outlet face 2b of the turbine casing 2c in order to remove the exhaust gases from the turbine 2.

[0068] In the embodiment shown in the Figures, except for FIG. 1, the turbine 2 thus comprises an inlet face 2a for the exhaust gases of the first and second ducts 4, 6 penetrating via their extensions 4, 8 into the turbine 2 and an outlet face 2b connected externally to the third duct 9 outside the turbine 2.

[0069] According to a characteristic of the present invention, the main expansion passage 4 inside the turbine 2 is provided with a regulation valve 13. This regulation valve 13 can advantageously be located near the outlet face 2b of the turbine 2, selectively shutting off or opening an outlet end 4b of the main expansion passage 4, thus being located in the main expansion passage 4 after the impeller of the turbine 2.

[0070] Whatever its position in the main expansion passage 4 extending the first duct 4, the regulation valve 13 can be provided with an actuator 15 moving it between at least a first position of closing the main expansion passage 4 with a zero flow in the main expansion passage 4 and a second completely open position of the main expansion passage 4 with a maximum flow in the main expansion passage 4.

[0071] The zero flow in the main expansion passage 4 can correspond to a demand for heating the decontamination elements 10 while the maximum flow in the main expansion passage 4 can correspond to a demand for maximum power to the compressor 3 of the turbocharger.

[0072] The actuator 15 can also move the regulation valve 13 into intermediate opening positions corresponding to different flows in the main expansion passage 4 depending on the degree of opening corresponding to each respective intermediate position.

[0073] Advantageously, the regulation valve 13 can be in the form of a disk that can be moved by the actuator 15 in translation or rotation. A disk that can be moved in rotation as a regulation valve 13 is shown specifically in FIGS. 5, 5a, 7 and 7a.

[0074] Referring to all of the Figures, except FIG. 1, the bypass portion 8 extending the second duct 6 can have an outlet end 8b and the main expansion passage 4 of the first duct 4 can have an outlet end 4b, the two outlet ends 4b, 8b opening out near the outlet face 2b of the turbine 2, in other words upstream of this outlet face 2b in the turbine 2. The third duct 9, outside the turbine 2, leads from the outlet face 2b in order to remove the exhaust gases from the turbine 2. In a conventional manner, the third duct 9 comprises further downstream of the outlet face 2b of the casing 2c of the turbine 2 decontamination elements 10 for the exhaust gases passing through it, these decontamination elements 10 having been mentioned previously.

[0075] It must be borne in mind that several bypass portions 8 extending the second so-called discharge duct 6 can exist simultaneously and that one bypass portion 8 can have several outlet ends 8b. FIGS. 3, 3a, 4, 5 and 5a show one outlet end 8b for one bypass portion 8 while FIGS. 6, 7a and 7b show several outlet ends 8b for one or more bypass portions 8.

[0076] The main expansion passage 4 extending the first duct 4 can also have an outlet end 4b in the place where the main expansion passage 4 and the bypass portion or portions 8 join. The outlet end 4b of the main expansion passage 4 can have a larger section than the section of the outlet end or ends 8b of the bypass portion or portions 8 but this is not compulsory. The outlet end 4b of the main expansion passage 4 advantageously has a circular section, which is not, however, limiting.

[0077] For example, the bypass portion or portions 8 can comprise at least two outlet ends 8b. This is shown specifically in FIGS. 6, 7 and 7a. Multiple outlet ends 8b for the bypass portion 8 extending the second discharge duct 6 can be located in a plane parallel to or aligned with that of the outlet face 2b of the turbine 2.

[0078] In a first non-limiting embodiment of the invention, the two or more than two outlet ends 8b of a bypass portion 8 can be located adjacent to one another in the turbine 2, which is not shown in the Figures. Alternatively, in a second also non-limiting embodiment of the invention, the two outlet ends 8b of the bypass portion or portions 8 can be distributed uniformly round an outlet disk arranged around the outlet end 4b of the main expansion passage 4 thus being located in the center of the disk, as shown in FIGS. 6, 7a and 7b.

[0079] The two or more than two outlet ends 8b of said at least one bypass portion 8 can open out radially or axially in relation to the outlet end 4b of the first duct 4. A radial opening out with a uniform distribution optimizes the configuration of the casing 2c and associated turbine 2 as well as optimizing the turbulences on the outlet face 2b of the casing 2c of the turbine 2.

[0080] In this embodiment, the two or more than two outlet ends 8b of the bypass portion or portions 8 can be at least three in number, all opening out radially or axially or some of the outlet ends 8b opening out radially and some of the other outlet ends 8b opening out axially. This is shown in FIGS. 6, 7 and 7a.

[0081] With a second so-called discharge duct 6 extended into the turbine 2 by one or more bypass portions 8, themselves having one or more outlet ends 8b and a main expansion passage 4 extending the first so-called exhaust duct 4 through the turbine provided with an outlet end 4b, the section of the outlet ends 8b, 4b can have various different forms namely, for example: [0082] a round form such as, for example, in a conventional turbocharger system, [0083] an optimized form to optimize the turbine assembly 2 and its associated casing 2c and to optimize the turbulences at the outlet face 2b of the turbine 2, for example a crescent, half-moon, ovalized, square, rectangular, triangular form, etc.

[0084] In an embodiment of the invention, the engine outlet can comprise at least one cylinder equipping the engine and advantageously three, first and second outlet passages closed by a respective exhaust valve, a series of first outlet passages of the cylinders supplying, via the first outlet manifold 5, the first so-called exhaust duct 4 through the turbine and a series of second outlet passages, via the second outlet manifold 7, supplying the second so-called discharge duct 6.

[0085] Thus, it is possible to obtain multiple regulations of exhaust gas flows. In specific conditions of operation of the engine assembly 1, it is advantageous to close or reduce the flow of exhaust gas in the main expansion passage 4 of the turbine 2. This is done by closing at least partially the regulation valve 13 according to the present invention.

[0086] It may also be possible to regulate the flow in the first duct 4 and to regulate that of the second duct 6, which allows an improved operation of the engine assembly.

[0087] The first specific conditions of operation of the engine assembly 1 will now be described, for which it is advantageous to shut off or reduce the flow of exhaust gas through the regulation valve 13 in the main expansion passage 4 extending the first duct 4.

[0088] As previously stated, the exhaust system comprises, upstream of the turbine 2, decontamination elements 10 for the exhaust gas passing through it, these being located in the third duct 9. These decontamination elements 10 need to be heated by being passed through by exhaust gases as hot as possible in order to reach as soon as possible a predetermined minimum temperature to ensure the decontamination treatment. This is particularly important during the period of time following the start-up of the motor vehicle.

[0089] It is advantageous to close or reduce the flow of exhaust gas in the main expansion passage 4 extending the first duct 4, this flow losing a great deal of heat in the impeller of the turbine 2 and thus being cooler than the flow in the second duct 6 having bypassed the turbine 2.

[0090] The invention thus also concerns a method of heating up the decontamination elements 10 in the exhaust system of an engine assembly described above, wherein the regulation valve 13 keeps the exhaust gas flow in the main expansion passage 4 inside the turbine 2 at a zero or reduced value until said minimum temperature is reached.

[0091] In the method according to the present invention, a suspensive condition for keeping the flow of exhaust gas in the main expansion passage 4 at a zero or reduced value is that the pressure at the engine's air intake is higher than atmospheric pressure. This corresponds to a demand for power of the engine assembly 1.

[0092] Incidentally, as shown in FIG. 2, an EGR line can be connected via a branch point 12 to one of the two ducts 4, 6 or to one of their respective extensions in the turbine 2. FIG. 2 shows a branch point 12 of an EGR line 11 through the turbine 2 either with the main expansion passage or with at least one bypass portion 8 or with both.

[0093] As previously mentioned, the turbine 2 can be provided with a cooling circuit using a cooling liquid within it, specifically water. This circuit is not shown in the Figures but by referring to FIGS. 2 to 7a for the references of the other elements, the cooling circuit can extend inside the casing 2c at least around the inlet face 2a and around the impeller of the turbine 2.

[0094] The cooling liquid advantageously circulates in all of the hot areas where a risk of melting of the material of the casing 2c and the turbine 2 is identified. The circulation of the cooling liquid occurs globally in one direction while travelling all round the casing 2c or the turbine 2, mainly in the area of an inlet flange of the turbine 2 and in the area around the impeller of the turbine 2.

[0095] Several preferred embodiments of the cooling circuit are possible. Thus, when the first 5 or the second 7 exhaust manifold comprises a cooling circuit, its cooling circuit can be connected to the cooling circuit of the turbine 2, with an inlet and outlet of the cooling circuit of the turbine 2 possibly located on the inlet face 2a of the turbine 2. In another embodiment, the cooling circuit of the turbine 2 is independent of that of each exhaust manifold 5, 7 and belongs to it. It is also possible for the turbine to be directly connected to the exhaust manifolds 5, 7 of the first and second ducts 4, 6 being then incorporated into their respective manifold 5, 7.

[0096] The invention is in no way limited to the embodiments described and illustrated, which have been given purely by way of example.