Exhaust gas recirculation compressor inlet thermal separation system

Abstract

An exhaust gas recirculation (EGR) system that utilizes an insulated separation wall that separates the hot, humid EGR gas duct from the cool, dry inlet air duct in the upstream proximity of the compressor inlet of the associated turbocharger compressor. This insulated separation wall inhibits the condensation of water droplets and the formation of ice particles near the mixing point of the EGR gases and inlet air in the upstream proximity of the compressor inlet, such that the turbocharger compressor wheel, blades, and other components are not subsequently damaged by the condensed water droplets or formed ice particles. The added insulation in this cold sink area essentially thermally isolates the hot, humid EGR gas flow from the cool, dry inlet air flow until the actual mixing point of the flows.

Claims

1. An exhaust gas recirculation (EGR) compressor inlet thermal separation system, comprising: an EGR gas duct adapted to carry EGR gas to a compressor inlet area disposed adjacent to a compressor; an inlet air duct adapted to carry inlet air to the compressor inlet area disposed adjacent to the compressor, wherein the EGR gas is relatively hotter and more humid than the inlet air; and an insulated separation wall disposed between the EGR gas duct and the inlet air duct adjacent to the compressor inlet area, wherein the insulated separation wall is adapted to thermally insulate the EGR gas from the inlet air until the EGR gas is mixed with the inlet air in or after the compressor inlet area; wherein the EGR gas duct is disposed adjacent to the inlet air duct and intersects the compressor inlet area at an angle to the inlet air duct subsequent to the insulated separation wall.

2. The EGR compressor inlet thermal separation system of claim 1, further comprising a ported shroud structure in which the EGR gas duct, the inlet air duct, and the insulated separation wall are formed or disposed.

3. The EGR compressor inlet thermal separation system of claim 2, wherein the ported shroud structure partially or wholly defines the compressor inlet area.

4. The EGR compressor inlet thermal separation system of claim 1, wherein the insulated separation wall comprises one or more of a non-metallic material and a structure adapted to trap a gas in one or more voids.

5. The EGR compressor inlet thermal separation system of claim 4, wherein the insulated separation wall comprises a composite, plastic, or foam material interspersed with a metallic material.

6. The EGR compressor inlet thermal separation system of claim 4, wherein the insulated separation wall comprises a composite, plastic, or, foam material that defines one or more gas-filled voids.

7. The EGR compressor inlet thermal separation system of claim 4, wherein the insulated separation wall comprises a honeycomb structured metallic material that defines one or more gas-filled voids.

8. The EGR compressor inlet thermal separation system of claim 4, wherein the insulated separation wall comprises one or more of the non-metallic material and the structure adapted to trap the gas in one or more voids coupled to a metallic wall.

9. A vehicle, comprising: a turbocharger compressor; an exhaust gas recirculation (EGR) system coupled to the compressor; and an EGR compressor inlet thermal separation system coupled to the compressor, comprising: an EGR gas duct adapted to carry EGR gas to a compressor inlet area disposed adjacent to a compressor; an inlet air duct adapted to carry inlet air to the compressor inlet area disposed adjacent to the compressor, wherein the EGR gas is relatively hotter and more humid than the inlet air; and an insulated separation wall disposed between the EGR gas duct and the inlet air duct adjacent to the compressor inlet area, wherein the insulated separation wall is adapted to thermally insulate the EGR gas from the inlet air until the EGR gas is mixed with the inlet air in or after the compressor inlet area; wherein the EGR gas duct is disposed adjacent to the inlet air duct and intersects the compressor inlet area at an angle to the inlet air duct subsequent to the insulated separation wall.

10. The vehicle of claim 9, wherein the EGR compressor inlet thermal separation system further comprises a ported shroud structure in which the EGR gas duct, the inlet air duct, and the insulated separation wall are formed or disposed.

11. The vehicle of claim 10, wherein the ported shroud structure partially or wholly defines the compressor inlet area.

12. The vehicle of claim 9, wherein the insulated separation wall comprises one or more of a non-metallic material and a structure adapted to trap a gas in one or more voids.

13. The vehicle of claim 12, wherein the insulated separation wall comprises a composite, plastic, or foam material interspersed with a metallic material.

14. The vehicle of claim 12, wherein the insulated separation wall comprises a composite, plastic, or, foam material that defines one or more gas-filled voids.

15. The vehicle of claim 12, wherein the insulated separation wall comprises a honeycomb structured metallic material that defines one or more gas-filled voids.

16. The vehicle of claim 12, wherein the insulated separation wall comprises one or more of the non-metallic material and the structure adapted to trap the gas in one or more voids coupled to a metallic wall.

17. An exhaust gas recirculation (EGR) compressor inlet thermal separation method, comprising: delivering EGR gas to a compressor inlet area disposed adjacent to a compressor via an EGR gas duct; delivering inlet air to the compressor inlet area disposed adjacent to the compressor via an inlet air duct, wherein the EGR gas is relatively hotter and more humid than the inlet air; and thermally insulating a separation wall disposed between the EGR gas duct and the inlet air duct adjacent to the compressor inlet area to thermally insulate the EGR gas from the inlet air until the EGR gas is mixed with the inlet air in or after the compressor inlet area; wherein the EGR gas duct is disposed adjacent to the inlet air duct and intersects the compressor inlet area at an angle to the inlet air duct subsequent to the insulated separation wall.

18. The EGR compressor inlet thermal separation method of claim 17, wherein thermally insulating the separation wall disposed between the EGR gas duct and the inlet air duct adjacent to the compressor inlet area comprises providing a separation wall comprising one or more of a non-metallic material and a structure configured to trap a gas in one or more voids.

19. The EGR compressor inlet thermal separation method of claim 17, wherein the EGR gas duct, the inlet air duct, and the insulated separation wall are formed or disposed in a ported shroud structure.

20. The EGR compressor inlet thermal separation method of claim 19, wherein the ported shroud structure partially or wholly defines the compressor inlet area.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present invention is illustrated and described herein with reference to the various drawings, in which like reference numbers are used to denote like system components/method steps, as appropriate, and in which:

(2) FIG. 1 is a cut-away perspective view of a conventional ported shroud and compressor inlet area of an EGR system, highlighting the problematic condensation of water drop near the mixing point of the associated EGR gases and inlet air;

(3) FIG. 2 is a schematic diagram illustrating the mechanism by which condensed water droplets can damage a turbocharger compressor component;

(4) FIG. 3 is a cut-away perspective view of one exemplary embodiment of a ported shroud and compressor inlet area of an EGR system utilizing the insulated separation wall provided herein, the ported shroud in a partially installed configuration;

(5) FIG. 4 is another perspective view of one exemplary embodiment of the ported shroud and compressor inlet area of the EGR system utilizing the insulated separation wall provided herein;

(6) FIG. 5 is a further perspective view of one exemplary embodiment of the ported shroud and compressor inlet area of the EGR system utilizing the insulated separation wall provided herein, the ported shroud again in a partially installed configuration;

(7) FIG. 6 is a still further perspective view of one exemplary embodiment of the ported shroud and compressor inlet area of the EGR system utilizing the insulated separation wall provided herein; and

(8) FIG. 7 is a still further perspective end view of one exemplary embodiment of the ported shroud and compressor inlet area of the EGR system utilizing the insulated separation wall provided herein, the ported shroud again in a partially installed configuration.

DESCRIPTION OF EMBODIMENTS

(9) Again, the exhaust gas recirculation (EGR) system provided herein utilizes an insulated separation wall that separates the hot, humid EGR gas duct from the cool, dry inlet air duct in the upstream proximity of the compressor inlet of the associated turbocharger compressor. This insulated separation wall inhibits the condensation of water droplets and the formation of ice particles near the mixing point of the EGR gases and inlet air in the upstream proximity of the compressor inlet, such that the turbocharger compressor wheel, blades, and other components are not subsequently damaged by the condensed water droplets or formed ice particles. The added insulation in this cold sink area essentially thermally isolates the hot, humid EGR gas flow from the cool, dry inlet air flow until the actual mixing point of the flows.

(10) Referring now specifically to FIGS. 3-7, in one exemplary embodiment, the EGR thermal separation system 10 includes a ported shroud 12 that defines both an EGR gas duct 14 and an inlet air duct 16. The EGR gas duct 14 carries (low pressure (LP)) hot, humid EGR gas to a compressor inlet 18 that is minimally, partially, or wholly defined by the ported shroud 12. The inlet air duct carries cool, dry inlet air to the compressor inlet 18. The compressor inlet 18 can be partially or wholly defined by the compressor housing 20 upstream of the compressor 22, which includes a compressor wheel, compressor blades, and other compressor components, collectively operable for compressing the EGR gas and inlet air. The EGR gas and inlet air delivered to the compressor inlet 18 by the EGR gas duct 14 and the inlet air duct 16, respectively, are mixed together in the compressor inlet 18 upstream of the compressor 22, at the compressor 22 itself, or even after the compressor 22. In this exemplary embodiment, the ported shroud 12 is manufactured from a metallic material, such as an aluminum material. The inlet air duct 16 includes a cylindrical duct that essentially runs along the axis of rotation of the compressor wheel. The EGR gas duct 14 includes a flattened annular duct that runs along the bottom of the inlet air duct 16 and intersects the compressor inlet 18 at an angle to the axis of rotation of the compressor wheel. The final leg of the EGR gas duct 14 can be defined by the ported shroud 12 or by the compressor housing 20, depending on how the compressor inlet 18 is defined.

(11) As described above, if a conventional aluminum wall is used to separate the EGR gas duct 14 from the inlet air duct 16, the cool, dry inlet air can cool the thermally conductive wall and cause the condensation of water droplets (or even the formation of ice) in the hot, humid EGR gas on or adjacent to the cool thermally conductive wall. This is problematic when these water droplets (or ice particles) are carried by the EGR gas, likely mixed with the inlet air, and run through the compressor 22. Compressor wheel, blade, and other component damage can result. The potential for this water droplet/ice formation is why mixing of the EGR gas and inlet air is typically delayed as long as possible.

(12) To alleviate this problem, the ported shroud 12 instead uses a thermally insulated separation wall 24 to separate the EGR gas duct 14 from the air inlet duct 16, especially along the final leg of the ducts 14 and 16, where they are in close proximity. This thermally insulated separation wall 24 does not cool down significantly on the EGR gas duct side (or heat up significantly on the inlet air duct side). Thus, water droplets do not condense and ice particles do not form on the EGR gas duct side of the thermally insulated separation wall 24. Physical and thermal mixing of the EGR gas and inlet air is delayed until later in the compressor inlet 18, in the compressor 22 itself, or even after the compressor 22. Condensation/freezing is minimized or eliminated altogether.

(13) In one exemplary embodiment, the thermally insulated separation wall 24 includes a simple plastic or foam insert that replaces or is coupled to the conventional separation wall. The plastic or foam insert can have a tongue-like shape and preferably conforms to the curves of the lower portion of the cylindrical inlet air duct 16 and the upper portion of the flattened annular EGR gas duct 14. The plastic or foam insert can be thinner proximate to the compressor inlet 18 and compressor 22 and thicker distant from the compressor inlet 18 and compressor 22. Optionally, the plastic or foam insert defines one or more hollow internal voids that are filled with another thermally insulating material or a gas to enhance the overall thermal insulation properties of the plastic or foam insert and the EGR thermal separation system 10.

(14) In another exemplary embodiment, the thermally insulated separation wall 24 includes a plurality of smaller plastic or foam inserts that are disposed in slots or recesses manufactured into the conventional aluminum separation wall. Optionally, the plastic or foam inserts each define one or more hollow internal voids that are filled with another thermally insulating material or a gas to enhance the overall thermal insulation properties of the plastic or foam inserts and the EGR thermal separation system 10.

(15) In a further exemplary embodiment, the thermally insulated separation wall 24 includes a honeycombed or other porous metallic (e.g., aluminum) or non-metallic structure. The honeycombed or other porous structure defines one or more hollow internal voids that are filled with another thermally insulating material or a gas to enhance the overall thermal insulation properties of the honeycombed or other porous structure and the EGR thermal separation system 10.

(16) In general, the ported shroud 12, EGR gas duct 14, and inlet air duct 16 are all coupled to the surrounding conduits and structures via appropriate sealing surfaces incorporating gaskets, O-rings, or the like, as well as appropriate fastening devices or the like.

(17) In another exemplary embodiment, the exhaust gas recirculation (EGR) compressor inlet thermal separation method provided herein includes delivering EGR gas to the compressor inlet area 18 disposed adjacent to the compressor 22 via the EGR gas duct 14 and delivering inlet air to the compressor inlet area 18 disposed adjacent to the compressor 22 via the inlet air duct 16. Again, the EGR gas is relatively hotter and more humid than the inlet air. As described above, if a conventional aluminum wall is used to separate the EGR gas duct 14 from the inlet air duct 16, the cool, dry inlet air can cool the thermally conductive wall and cause the condensation of water droplets (or even the formation of ice) in the hot, humid EGR gas on or adjacent to the cool thermally conductive wall. This is problematic when these water droplets (or ice particles) are carried by the EGR gas, likely mixed with the inlet air, and run through the compressor 22. Compressor wheel, blade, and other component damage can result. The potential for this water droplet/ice formation is why mixing of the EGR gas and inlet air is typically delayed as long as possible.

(18) To alleviate this problem, the thermally insulating a separation wall 24 is disposed between the EGR gas duct 14 and the inlet air duct 16 adjacent to the compressor inlet area 18 to thermally insulate the EGR gas from the inlet air until the EGR gas is mixed with the inlet air in or after the compressor inlet area 18. In general, thermally insulating the separation wall 24 disposed between the EGR gas duct 14 and the inlet air duct 16 adjacent to the compressor inlet area 18 includes providing a separation wall 24 including one or more of a non-metallic material and a structure configured to trap a gas in one or more voids.

(19) Thus, again, the exhaust gas recirculation (EGR) system provided herein utilizes an insulated separation wall that separates the hot, humid EGR gas duct from the cool, dry inlet air duct in the upstream proximity of the compressor inlet of the associated turbocharger compressor. This insulated separation wall inhibits the condensation of water droplets and the formation of ice particles near the mixing point of the EGR gases and inlet air in the upstream proximity of the compressor inlet, such that the turbocharger compressor wheel, blades, and other components are not subsequently damaged by the condensed water droplets or formed ice particles. The added insulation in this cold sink area essentially thermally isolates the hot, humid EGR gas flow from the cool, dry inlet air flow until the actual mixing point of the flows.

(20) Although the present invention is illustrated and described herein with reference to preferred embodiments and specific examples thereof, it will be readily apparent to those of ordinary skill in the art that other embodiments and examples can perform similar functions and/or achieve like results. All such equivalent embodiments and examples are within the spirit and scope of the present invention, are contemplated thereby, and are intended to be covered by the following non-limiting claims for all purposes.