Exhaust Gas Management System

Abstract

The present invention relates to an exhaust gas management system which allows cooled exhaust gas recirculation as well as heat recovery through a single integrated module, located downstream of the exhaust line. Additionally, the present invention relates to a propulsion system wherein the cooled exhaust gas is recirculated to the intake manifold of an internal combustion engine.

Claims

1. An exhaust gas management system comprising: an exhaust duct comprising: a first end connectable to an exhaust manifold of an internal combustion engine, a second end open to the atmosphere; a heat recovery module adjacent to the second end of the exhaust duct, the heat recovery module comprising: a heat exchanger in bypass configuration with the exhaust duct having a first end and a second end, wherein the heat exchanger has a first inlet/outlet port and a second outlet/inlet port, wherein the first inlet/outlet port is the port closest to the first end of the exhaust duct and the second inlet/outlet port is the port closest to the second end of the exhaust duct; a bypass valve with at least two end positions including a first end position which establishes the passage of the exhaust gas through the heat exchanger and a second end position which establishes the passage of the exhaust gas through the exhaust duct; a recirculated exhaust gas recirculation duct, connectable to an air intake manifold of the internal combustion engine, wherein, in the operating mode, the recirculation duct establishes a fluid communication between an outlet of the heat exchanger of the heat recovery module and the air intake manifold; and a valve for regulating the recirculated gas flow which in the operating mode passes through the recirculation duct located adjacent to the air intake manifold.

2. The exhaust gas management system according to claim 1, wherein the system further comprises at least one exhaust gas post-treatment unit in the exhaust duct, located between a first end of said exhaust duct and the heat recovery module.

3. The exhaust gas management system according to claim 2, wherein the system further comprises a first deformable element in the exhaust duct, the first deformable element being located between the at least one exhaust gas post-treatment unit and the heat recovery module.

4. The exhaust gas management system according to claim 1, wherein the recirculation duct comprises a second deformable element.

5. The exhaust gas management system according to claim 1, wherein the paths of the exhaust gas through the heat exchanger and the exhaust duct are parallel.

6. The exhaust gas management system according to claim 1, wherein the bypass valve is located on the side of the first inlet/outlet port of the heat exchanger.

7. The exhaust gas management system according to claim 1, wherein the bypass valve is located on the side of the second inlet/outlet port of the heat exchanger.

8. The exhaust gas management system according to claim 1, wherein either the recirculation duct or the recirculated gas flow management valve has a first attachment interface configured for being coupled to either an engine block or to an air intake manifold of the engine block.

9. The exhaust gas management system according to claim 1, wherein the recirculation duct comprises a second attachment interface for attachment to the heat recovery module.

10. The system according to claim 1, wherein the recirculation duct is connected to the valve by means of a screwed attachment.

11. The system according to claim 1, further comprising: a propulsion system comprising: a naturally aspirated gasoline internal combustion engine comprising an air intake manifold; and an exhaust manifold; and wherein the exhaust gas recirculation duct is connected to the intake manifold, and the first end of the exhaust duct is connected to the exhaust manifold.

12. The system according to claim 11, wherein the internal combustion engine comprises an engine block for housing one or more combustion chambers, and the valve for regulating the recirculated exhaust gas flow is integrated in the engine block.

13. The system according to claim 11, wherein the valve for regulating the recirculated exhaust gas flow is integrated in the air intake manifold.

14. The system according to claim 11, wherein the entry of recirculated exhaust gas into the air intake manifold of the internal combustion engine is by means of a distribution rail for individually and homogeneously feeding each of the combustion chambers of the internal combustion engine.

Description

DESCRIPTION OF THE DRAWINGS

[0049] These and other features and advantages of the invention will become more apparent based on the following detailed description of a preferred embodiment, given solely by way of non-limiting illustrative example, in reference to the attached drawings.

[0050] FIG. 1 schematically shows an exhaust gas management system like those known in the state of the art.

[0051] FIG. 2 schematically shows a first embodiment of the invention in which the bypass valve is located on the side of the second port of the heat exchanger.

[0052] FIG. 3 schematically shows a second embodiment of the invention in which the valve for regulating the recirculated gas flow is located in an area very close to the feed of the cylinders of the internal combustion engine integrating the valve in the engine block.

[0053] FIGS. 4A and 4B schematically show a front view and top view, respectively, of an embodiment of the valve for regulating the recirculated gas flow according to the embodiment shown in the preceding figure.

[0054] FIG. 5 schematically shows a third embodiment of the invention in which the bypass valve is located on the side of the first port of the heat exchanger.

[0055] FIG. 6 schematically shows a fourth embodiment of the invention in which the recirculation duct and the valve for regulating the recirculated gas flow comprise two coupling interfaces which allow for an easier installation given the magnitude of the system.

DETAILED DESCRIPTION OF THE INVENTION

[0056] According to the first inventive aspect, the present invention relates to an exhaust gas management system which allows recirculating suitably cooled exhaust gas, specifically in a naturally aspirated gasoline engine; and recovering heat from the exhaust gas which would otherwise end up being discharged into the atmosphere.

[0057] According to the first inventive aspect, it has been verified that the use of feed means with EGR gas in a gasoline engine has shown various advantages: [0058] When the engine is working in low-load operation, the throttle of the air intake valve must be closed to allow entry of the air strictly necessary for assuring a stoichiometric mixture. Nevertheless, the closure of this throttle causes a negative pressure and therefore a pressure drop, reducing the volumetric efficiency of the engine. By incorporating EGR gas, the air intake valve must increase its opening, increasing the volumetric efficiency and therefore bringing the operating conditions of the engine close to its optimal conditions. [0059] It has been observed that the heating capacity of the mixture of fuel with air and the recirculated exhaust gas is maximized once conditions such that the tendency to self-detonate is reduced have been assured, and [0060] The excess potential of fuel above the air-to-fuel ratio normally used in these engines is eliminated, thereby cooling the exhaust gas since it may damage an exhaust component.

[0061] FIG. 1 shows an embodiment of an exhaust management system according to the state of the art. The figure schematically shows an internal combustion engine (1) comprising at least one intake manifold (1.1) for the entry of air into combustion chambers (1.3), and an exhaust manifold (1.2) through which hot gases from the combustion chambers (1.3) exit.

[0062] The hot gas without oxygen, or with minimum traces of oxygen, is finally expelled into the atmosphere through the exhaust line. The exhaust line comprises an exhaust duct (4) which at a first end (4.1) has a first group (2, 3) of gas treatment elements such as a particle filter (2) or a catalytic converter (3).

[0063] This first group of elements (2, 3) is close to the internal combustion engine (1) and therefore is at a high pressure, which pressure lessens the farther the group is from the exhaust manifold (1.2).

[0064] Two options are shown by means of discontinuous lines wherein a recirculation duct (7) takes part of the exhaust gas, at a high temperature and with a pressure greater than atmospheric pressure, and drives it to the air intake manifold (1.1) after reducing its temperature with a heat exchanger (10) for EGR gas.

[0065] The high pressure at the points of the exhaust line located around this first group of elements (2, 3) allows the recirculated gas going through the recirculation duct (7) to be introduced back into the intake with a given flow using a valve (8), the valve for regulating the recirculated gas.

[0066] The rest of the gas that is not recirculated continues its path along the exhaust line through the exhaust duct (4) until reaching the second end (4.2) open to the atmosphere, where the pressure is atmospheric pressure.

[0067] After the first group (2, 3) of elements of the exhaust line, FIG. 1 shows a first deformable element (5) which establishes a certain degree of independence in movements between the first group of elements (2, 3) together with the internal combustion engine (1) and the rest of the exhaust line, preventing for example the vibrations of the engine from being transmitted for the most part to the rest of the elements of the exhaust line located downstream. In particular, it prevents the transmission of vibrations to the long segment of the exhaust duct (4) passing below the vehicle which incorporates the internal combustion engine (1) as well as the exhaust management system such as the one described, reaching the second end (4.2) open to the atmosphere.

[0068] The same figure shows at one end of the exhaust line a heat recovery module (6) formed by a heat exchanger (6.1) in bypass configuration with the exhaust duct (4) and a bypass valve (6.2).

[0069] The bypass valve (6.2) has at least two end positions, a first end position which establishes the passage of the exhaust gas through the heat exchanger (6.1), and a second end position which establishes the passage of the gas through the exhaust duct (4).

[0070] In the first end position, the heat from the exhaust gas is transferred to a thermal fluid, typically a liquid coolant, for use in applications such as increasing the temperature at the start in an internal combustion engine so that it can reach the nominal temperature as soon as possible, heating the passenger compartment, or being used as a heat source for a Rankine cycle.

[0071] This heat recovery unit module (6) is independent of the EGR heat exchanger (10) and has no influence whatsoever on the pressure in the intake manifold (1.1) of the internal combustion engine (1).

First Embodiment of the Invention

[0072] FIG. 2 shows a first embodiment of the invention in which the specific heat exchanger (10) for EGR gas which was located right at the inlet of the intake manifold (1.1) is dispensed with and the exchanger of the recovery module (6) is established as a heat exchanger both for recovering heat and for cooling recirculated EGR gas. The rest of the elements in common with FIG. 1 are considered to have been described when the system according to the state of the art was described.

[0073] For this purpose, the outlet of the exchanger is established in the second port (6.1.2) and is communicated with the valve (8) for regulating the recirculated gas flow by means of a recirculation duct (7).

[0074] Although this heat recovery module (6) is located adjacent to the second end (4.2) of the exhaust duct (4) with a pressure close to atmospheric pressure, it has surprisingly been verified that in naturally aspirated gasoline engines, when the valve (8) for regulating the recirculated gas flow opens it has been observed that the gas flows at a sufficient flow with respect to the established target.

[0075] In the configuration shown in FIG. 2, the bypass valve (6.2) is located downstream according to the direction of flow in the exhaust duct (4), that is, on the cold side of the heat exchanger (6.1) which corresponds with the second port (6.1.2) in this embodiment.

[0076] When the bypass valve (6.2) is as shown in FIG. 2, in the second end position, the exhaust gas can pass directly through the exhaust duct (4) to the atmosphere. Nevertheless, part of the exhaust gas may enter through the inlet of the exchanger located in the first port (6.1.1), pass through the exchanger (6.1), transferring heat and reducing its temperature, and exit at the opposite end through the second port (6.1.2) of the heat exchanger (6.1) to continue through the recirculation duct (7) to the valve (8) for regulating the recirculated gas flow, entering the air intake manifold (1.1). In this embodiment, the inlet of the exchanger (6.1) through the first port (6.1.1) is at the end closest to the internal combustion engine (1) and the outlet of the exchanger (6.1) through the second port (6.1.2) is at the end closest to the outlet into the atmosphere according to the direction of the exhaust duct (4).

[0077] In this embodiment and in all the embodiments that are described below, the first port (6.1.1) of the heat exchanger (6.1) is a manifold and the second port (6.1.2) of the heat exchanger (6.1) is also a manifold.

[0078] When the bypass valve (6.2) is in the first end position, which would be represented with a vertical orientation according to FIG. 2, the exhaust gas cannot pass through the exhaust duct (4) in the segment arranged parallel to the heat exchanger (6.1) and must necessary cross said heat exchanger (6.1). After transferring heat, reducing its temperature upon passing through the heat exchanger (6.1), the gas: [0079] either returns to the exhaust duct (4) to be discharged into the atmosphere, or [0080] part of the gas is driven through the recirculation duct (7) to enter the intake manifold (1.1) of the internal combustion engine (1).

[0081] The purpose of the first option is to recover the heat which would otherwise end up being wasted in the atmosphere and the second option allows introducing the exhaust gas with a lower temperature at the intake, obtaining the already described characteristic benefits of an EGR system.

[0082] This same drawing schematically shows a distribution rail (9) in the air intake manifold (1.1) which allows distributing the air and recirculated gas mixture directly to the inlet of each combustion chamber (1.3), increasing feed condition homogeneity for all of them.

[0083] According to another embodiment, the recirculation duct (7) comprises a second deformable element (7.1) which also allows making movements between the ends of said recirculation duct (7) independent, for example movements due to expansions of such a long element connected with fixed attachments to devices located at its two ends or for decoupling the vibrations of the engine with respect to the components located at the second end (4.2) of the exhaust duct (4).

[0084] The specific solution of the use of a distribution rail (9), the specific solution of the use of a second deformable element (7.1), or both specific solutions simultaneously are applicable to any of the embodiments described herein.

[0085] In particular, according to other embodiments the first deformable element (5), the second deformable element (7.1), or both are elastic.

[0086] According to other embodiments, the first deformable element (5), the second deformable element (7.1), or both are configured like a bellows.

Second Embodiment of the Invention

[0087] FIG. 3 schematically shows a second embodiment in which most the elements have already been described in the first embodiment, whereby only those different elements with respect to the first embodiment will be described below.

[0088] In this embodiment, the valve (8) for regulating the recirculated gas flow or EGR gas has been installed integrated in the engine block (B) such that the manufacture of certain parts is avoided given that some surfaces of the valve (8) are formed by said engine block (B), and most importantly the valve (8) is located even closer to the combustion chambers (1.3), drastically reducing response inertia when recirculated gas is to be fed to the intake of the internal combustion engine (1).

[0089] Said FIG. 3 also shows a first attachment interface (I1) which allows the attachment between the recirculation duct (7) and the engine block (B) such that the recirculation duct (7) and the valve (8) for regulating the recirculated gas flow which is integrated in said engine block (B) are placed in fluid communication.

[0090] FIG. 4A and 4B schematically show a front view and top view, respectively, of an embodiment of the valve (8) according to the example shown in the preceding figure. FIG. 4A shows a section view of the engine block (B) with a housing (8.2) in which the valve (8) which is fixed on the upper surface of the engine block (B) is housed. The housing (8.2) is thereby formed on the very engine block (B) without having to manufacture specific parts, and an actuator (8.1), the actuator (8.1) of the valve (8), together with the closure elements, are fixed to the engine block (B).

[0091] FIG. 4B schematically shows the inlet (1.3.1) into the combustion chambers (1.3) very close to the valve (8) for regulating the recirculated gas flow, which means that with lower pressures in the recirculated gas the flow is increased.

Third Embodiment of the Invention

[0092] FIG. 5 schematically shows a third embodiment of the invention in which the bypass valve (6.2) is located upstream the heat recovery module (6) following the direction of flow of the exhaust gas along the exhaust duct (4), that is, on the side where the first port (6.1.1) is located. Additionally, the end of the heat exchanger (6.1) connected to the recirculation duct (7) is now upstream of the module (6). The connection is established in the first port (6.1.1).

[0093] In FIG. 5, the bypass valve (6.2) is depicted in the second position, which establishes the passage of the gas through the exhaust duct (4) where the hot gas circulating through the exhaust duct (4) continues until the second end (4.2) of the exhaust duct (4) with free access to the atmosphere. In this position of the flap of the bypass valve (6.2), there is no heat recovery save a small unwanted recovery value through the access of the hot gas into the tube bundle of the heat exchanger. Nevertheless, the recirculated gas inlet passing through the heat exchanger (6.1) in the upstream direction is available, following the same references with respect to the direction of flow in the exhaust duct (4), that is entering through the second port (6.1.2). The flow of the recirculated gas is shown using an arrow with a discontinuous thick line.

[0094] In the first end position, not shown in FIG. 5, the bypass valve (6.2) is positioned in a transverse manner, closing the passage through the exhaust duct (4) in the bypass configuration and is forced to pass through the heat exchanger (6.1), this time in the downstream direction according to the direction of the exhaust duct (4), to be incorporated again into said exhaust duct (4) and finally be discharged into the atmosphere. That is, in this case the exhaust gas enters through the first port (6.1.1) into the heat exchanger (6.1) and exits through the second port (6.1.2).

[0095] In this first end position of the bypass valve (6.2), the direction of flow inside the heat exchanger (6.1) is opposite the direction of flow when the bypass valve (6.2) is in the second end position. In said first end position of the bypass valve (6.2), the heat recovery module (6) operates by recovering heat from the exhaust gas.

[0096] This configuration is applicable to all the preceding examples which described specific aspects of the deformable elements (5, 7.1), position of the EGR valve (8) for regulating the recirculated gas flow, and the use of the distribution rail (9) for feeding the combustion chambers (1.3).

Fourth Embodiment of the Invention

[0097] FIG. 6 schematically shows a fourth embodiment of the invention in which the recirculation duct (7) and the valve (8) for regulating the recirculated gas flow comprise two coupling interfaces.

[0098] A first interface (I1) allows the attachment of the valve (8) for regulating the recirculated gas flow to either the engine block (B), which is the option explicitly shown in FIG. 6, or the intake manifold.

[0099] A second interface (I2) allows the attachment of the recirculation duct (7) to the heat exchanger (6.1) of the heat recovery module (6).

[0100] According to this embodiment, easy installation of the assembly formed by the recirculation duct (7) and the valve (8) for regulating the recirculated gas flow with the rest of the exhaust gas management system is possible.

[0101] According to preferred embodiments of the invention, any of the described examples uses parallel exhaust gas paths through the heat exchanger (6.1) and the exhaust duct (4).

[0102] All the embodiments show the exhaust gas management system attached to an internal combustion engine, specifically a naturally aspirated gasoline engine. A second aspect of the invention relates to any of the propulsion systems combining both the internal combustion engine (1) and the exhaust gas management system like those described, as well as the vehicle incorporating such propulsion system.