EXHAUST GAS RECIRCULATION APPARATUS

Abstract

The present disclosure describes an exhaust gas recirculation (EGR) apparatus for a turbocharged internal combustion engine, the EGR apparatus comprising: an air intake duct with a throttle valve configured to control an intake air quantity flowing through the air intake duct to a turbocharger compressor; an exhaust gas recirculation inlet connected to the air intake duct downstream of the throttle valve; and an EGR valve configured to control an exhaust gas quantity recirculated to the turbocharger compressor via the exhaust gas recirculation inlet, wherein the throttle valve and the EGR valve are combined in a single valve unit in which the valves are separated by a separating element configured to substantially prevent exhaust gas from entering the air intake duct in a vicinity of the throttle valve.

Claims

1. An exhaust gas recirculation (EGR) apparatus for a turbocharged internal combustion engine, the EGR apparatus comprising: an air intake duct with a throttle valve configured to control an intake air quantity flowing through the air intake duct to a turbocharger compressor; an exhaust gas recirculation inlet connected to the air intake duct downstream of the throttle valve; and an EGR valve configured to control an exhaust gas quantity recirculated to the turbocharger compressor via the exhaust gas recirculation inlet, wherein the throttle valve and the EGR valve are combined in a single valve unit in which the valves are separated by a separating element configured to substantially prevent exhaust gas from entering the air intake duct in a vicinity of the throttle valve.

2. The EGR apparatus according to claim 1, wherein the valve unit has a main valve body defining a passage through which exhaust gas flows to the exhaust gas recirculation inlet when a movable valve element of the EGR valve is in an open position, and the separating element is disposed between the passage of the valve body and the throttle valve.

3. The EGR apparatus according to claim 2, wherein the movable valve element of the EGR valve is mechanically connected to a movable valve element of the throttle valve by a valve stem which passes through a gap in the separating element.

4. The EGR apparatus according to claim 2, wherein the exhaust gas recirculation inlet comprises a conduit which fluidly connects the passage of the valve body to an interior of the air intake duct downstream of the throttle valve.

5. The EGR apparatus according to claim 2, wherein the separating element comprises a plate formed as an integral cast part of the EGR apparatus.

6. The EGR apparatus according to claim 2, wherein the separating element comprises a plate formed as a component which is inserted between the passage and the throttle valve.

7. The EGR apparatus according to claim 1, wherein the throttle valve comprises a throttle flap.

8. The EGR apparatus according to claim 1, wherein the EGR valve comprises a poppet valve.

9. An engine system, comprising: an internal combustion engine having an intake manifold and an exhaust manifold; a turbocharger mounted on the engine, the turbocharger including a turbine fluidly connected to the exhaust manifold and a compressor fluidly connected to the intake manifold; and an exhaust gas recirculation (EGR) apparatus comprising: an air intake duct with a throttle valve configured to control an intake air quantity flowing through the air intake duct to a turbocharger compressor; an exhaust gas recirculation inlet connected to the air intake duct downstream of the throttle valve; and an EGR valve configured to control an exhaust gas quantity recirculated to the turbocharger compressor via the exhaust gas recirculation inlet, wherein the throttle valve and the EGR valve are combined in a single valve unit in which the valves are separated by a separating element configured to substantially prevent exhaust gas from entering the air intake duct in a vicinity of the throttle valve.

10. An exhaust gas recirculation (EGR) method for a turbocharged internal combustion engine, the EGR method comprising: controlling, by a throttle valve, an intake air quantity flowing through an air intake duct provided with the throttle valve to a turbocharger compressor; and controlling, by an EGR valve which is combined with the throttle valve in a single valve unit in which the valves are separated by a separating element configured to substantially prevent exhaust gas from entering the air intake duct in a vicinity of the throttle valve, an exhaust gas quantity recirculated to the turbocharger compressor via an exhaust gas recirculation inlet connected to the air intake duct downstream of the throttle valve.

11. The EGR apparatus according to claim 3, wherein the exhaust gas recirculation inlet comprises a conduit which fluidly connects the passage of the valve body to an interior of the air intake duct downstream of the throttle valve.

12. The EGR apparatus according to claim 4, wherein the separating element comprises a plate formed as an integral cast part of the EGR apparatus.

13. The EGR apparatus according to claim 4, wherein the separating element comprises a plate formed as a component which is inserted between the passage and the throttle valve.

14. The EGR apparatus according to claim 2, wherein the EGR valve comprises a poppet valve.

15. The EGR apparatus according to claim 4, wherein the EGR valve comprises a poppet valve.

16. The exhaust gas recirculation method of claim 10, wherein the valve unit has a main valve body defining a passage through which exhaust gas flows to the exhaust gas recirculation inlet when a movable valve element of the EGR valve is in an open position, and the separating element is disposed between the passage of the valve body and the throttle valve.

17. The exhaust gas recirculation method of claim 16, wherein the movable valve element of the EGR valve is mechanically connected to a movable valve element of the throttle valve by a valve stem which passes through a gap in the separating element.

18. The exhaust gas recirculation method of claim 16, wherein the exhaust gas recirculation inlet comprises a conduit which fluidly connects the passage of the valve body to an interior of the air intake duct downstream of the throttle valve.

19. The exhaust gas recirculation method of claim 16, wherein the separating element comprises a plate formed as a component which is inserted between the passage and the throttle valve.

20. The exhaust gas recirculation method of claim 10, wherein the throttle valve comprises a throttle flap; and wherein the EGR valve comprises a poppet valve.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Reference will be made, by way of example, to the accompanying drawings, wherein like reference numerals refer to the like elements throughout and in which:

[0017] FIG. 1 is a cross-sectional schematic diagram of a low-pressure EGR apparatus;

[0018] FIG. 2 is a cross-sectional schematic diagram of a close-coupled low-pressure EGR apparatus;

[0019] FIG. 3 is a cross-sectional schematic diagram of a detached low-pressure EGR apparatus;

[0020] FIG. 4 is a cross-sectional schematic diagram of a low-pressure EGR apparatus according to the present disclosure; and

[0021] FIG. 5 is perspective schematic diagram of the low-pressure EGR apparatus of FIG. 4.

DETAILED DESCRIPTION

[0022] For a better understanding of the present disclosure, a brief overview of low-pressure exhaust gas recirculation (EGR) systems will be given first. In low-pressure EGR systems, exhaust gas generated by an engine exits through an exhaust manifold and passes through a turbocharger turbine which powers a turbocharger compressor. The exhaust gas then flows either into an exhaust pipe, from which the exhaust gas leaves the vehicle, or into an EGR loop. In the low-pressure EGR loop, the exhaust gas passes through a low pressure EGR cooler, which cools the temperature of the exhaust gas, subsequent to which it passes through an EGR valve and then is mixed with air in an air intake duct. The mixture of air and exhaust gas is then introduced to the turbocharger compressor which pressurizes the mixed intake gas. The high-pressure mixture is then passed through a charge air cooler into an intake manifold of the engine.

[0023] FIG. 1 is a schematic diagram of an EGR apparatus 10 which can be implemented as part of a low pressure EGR system. The EGR apparatus 10 comprises a throttle valve 14 and an EGR valve 16 that are combined together as a single valve unit, referred to herein as a combination valve (or combi-valve for short), in which the amount of intake air supplied to the turbocharger compressor and the amount of exhaust gas recirculated to the turbocharger compressor is simultaneously controlled.

[0024] In particular, the throttle valve 14 is arranged between an inlet 18 and an outlet 20 of an air intake duct 12, and controls the amount of intake air supplied to the turbocharger by opening or closing the air intake duct 12. The air intake duct 12 directs intake air toward the turbocharger compressor (not depicted in FIG. 1), and can be of circular or some other cross section. The throttle valve 14 can be any suitable valve for controlling the flow of intake air through the air intake duct 12, though in this example the throttle valve 14 comprises a throttle flap (throttle plate) 26 mounted on a hinge 28. The hinge 28 serves as an actuator which changes the position of the throttle flap 26 between open and closed positions. However, any type of controlling mechanism such as a solenoid, pneumatic, hydraulic actuator or other type of mechanism can be provided.

[0025] The EGR valve 16 is arranged in an EGR path, and controls the amount of exhaust gas recirculated to the turbocharger by opening or closing the EGR path. In particular, the EGR valve allows a flow of exhaust gas to the air intake duct 12 when in an open position, and blocks the flow of exhaust gas to the air intake duct 12 when in a closed position. In more detail, the EGR valve 16 comprises a valve head 38 and a valve seat 40, which is an aperture positioned in a path of exhaust gas flow between an inlet port 34 and an outlet port 36 of a main body 32 of the combination valve. The valve head 38 is movable between the closed position where the valve head 38 is seated on (brought into contact with), and seals, the valve seat 40, and the open position where the valve head 38 is lifted away from the valve seat 40. Thus, in this particular example, the EGR valve 16 is a lifting valve such as a poppet valve. However, the EGR valve 16 can be any suitable valve for controlling the flow of exhaust gas.

[0026] The valve head 38 of the EGR valve 16 is connected to the throttle flap 26 by a valve stem 42. In this way, the combination valve can simultaneously control the flow of intake air through the air intake duct 12 and the flow of exhaust gas recirculated to the air intake duct 12, that is simultaneously close the air intake duct 12 and open the exhaust gas path (or open the air intake duct 12 and close the exhaust gas path), by means of a single actuator, i.e., the hinge 28.

[0027] The EGR apparatus 10 shown in FIG. 1 has the disadvantage that the exhaust gas entry location is the same as the throttle valve location. As noted previously, on the one hand it is desirable for the EGR gases to be introduced close to the compressor face, but on the other hand it is also desirable for the throttle to be placed at a distance from the compressor face. In a close-coupled combination valve, as shown in FIG. 2, the throttle flap causes major disturbances to the oncoming clean air (shown in FIG. 2 as wavy lines and large arrow, respectively). This unstable, turbulent air directly in front of the compressor (i.e., the compressor wheel) reduces the operational efficiency of the compressor. A uniform and stable flow is desired for optimum compressor performance. On the other hand, in a detached combination valve, as shown in FIG. 3, the combination valve is moved further back from the compressor. However, this increases the risk of damage to the compressor wheel from condensate formation. Specifically, when hot EGR gasses from the exhaust gas inlet meet cold inlet gases from the fresh air inlet, condensate is formed at the mixing point/zone. A longer duct provides a greater distance in which the initial mist can coalesce into larger water droplets (shown in FIG. 3 as drops). These large water droplets significantly reduce the life of the compressor wheel and will eventually lead to compressor failure. Accordingly, a compromise must be made when choosing the distance from the combination valve from the turbocharger compressor. The issues outlined above can be resolved by using separate throttle and EGR valves. However, this would negate the weight, complexity and cost benefits of the combined throttle/EGR valve.

[0028] FIGS. 4 and 5 are schematic diagrams of an EGR apparatus in which the exhaust gas entry point to the air intake duct is separated from the main body of the combination valve. Similar to the EGR apparatus 10 depicted in FIG. 1, the EGR apparatus 10 depicted in FIGS. 4 and 5 comprises a throttle valve 14 and an EGR valve 16. As before, the throttle valve 14 comprises a pivotable element 26 (throttle flap) driven by an actuator 28, and the EGR valve 16 comprises a valve head 38 and a valve seat 40 formed such that an exhaust gas flow path (indicated by the dashed line) is created for exhaust gas to flow through when the valve head 38 is in an open position. However, in contrast to the EGR apparatuses depicted in FIGS. 1 to 3, the outlet port 36 of the valve body 32 is fluidly connected to an exhaust gas recirculation inlet 48 that is connected to the air intake duct 12 downstream of the throttle valve 14. In particular, the exhaust gas recirculation inlet 48 comprises a conduit extending from the outlet port 36 of the valve body 32 to an opening 52 into the air intake duct 12. The exhaust gas recirculation inlet may have any size, shape or configuration suitable for directing exhaust gas to the air intake duct 12. The EGR valve 14 is separated from the throttle valve 14 by a plate 56 which is configured to substantially prevent exhaust gas from entering the interior of the air intake duct in a vicinity of the throttle valve 14. Thus, when the EGR valve 16 is in the open position (as depicted in FIGS. 4 and 5), recirculated exhaust gas passes from the inlet port 34 of the valve body 32, in which the movable valve element 38 of the EGR valve 16 is disposed, to the outlet port 36 of the valve body 32. From there, the recirculated exhaust gas enters the conduit and flows to the opening 52 of the air intake duct 12. To allow the throttle valve 14 and EGR valve 16 to operate in unison, the plate 56 includes a slot 56 through which the valve stem 42 extends. Advantageously, the EGR apparatus depicted in FIGS. 4 and 5 retains the combined nature of the throttle and EGR valves, while providing a separate path for the recirculated exhaust gas.

[0029] FIGS. 1-5 show example configurations with relative positioning of the various components. If shown directly contacting each other, or directly coupled, then such elements may be referred to as directly contacting or directly coupled, respectively, at least in one example. Similarly, elements shown contiguous or adjacent to one another may be contiguous or adjacent to each other, respectively, at least in one example. As an example, components laying in face-sharing contact with each other may be referred to as in face-sharing contact. As another example, elements positioned apart from each other with only a space there-between and no other components may be referred to as such, in at least one example. As yet another example, elements shown above/below one another, at opposite sides to one another, or to the left/right of one another may be referred to as such, relative to one another. Further, as shown in the figures, a topmost element or point of element may be referred to as a top of the component and a bottommost element or point of the element may be referred to as a bottom of the component, in at least one example. As used herein, top/bottom, upper/lower, above/below, may be relative to a vertical axis of the figures and used to describe positioning of elements of the figures relative to one another. As such, elements shown above other elements are positioned vertically above the other elements, in one example. As yet another example, shapes of the elements depicted within the figures may be referred to as having those shapes (e.g., such as being circular, straight, planar, curved, rounded, chamfered, angled, or the like). Further, elements shown intersecting one another may be referred to as intersecting elements or intersecting one another, in at least one example. Further still, an element shown within another element or shown outside of another element may be referred as such, in one example.

[0030] Spatially relative terms, such as inner, outer, beneath, below, lower, above, upper, and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. Spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as below or beneath other elements or features would then be oriented above the other elements or features. Thus, the example term below can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

[0031] It will be appreciated by those skilled in the art that although the invention has been described by way of example, with reference to one or more examples, it is not limited to the disclosed examples and that alternative examples could be constructed without departing from the scope of the invention as defined by the appended claims.

[0032] The subject matter claimed herein is not limited to embodiments that solve any disadvantages or that operate only in environments such as those described above. Rather, these are only provided to illustrate example technology areas where some embodiments described herein may be practiced.

[0033] All examples and conditional language recited herein are intended to aid the reader in understanding the invention and the concepts contributed by the inventor to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions. Although embodiments have been described in detail, it should be understood that the various changes, substitutions, and alterations could be made without departing from the spirit and scope of the disclosure.