Claims
- 1. An exhaust gas recirculation system for an engine, comprising:
- an exhaust system for carrying exhaust gas away from the engine;
- an intake system comprising a pipe arrangement for distributing intake air to cylinders of the engine, the pipe arrangement comprising a collector section, a plurality of branches leading from the collector section, respectively, to the cylinders of the engine, and an intake passage section for introducing the intake air into the collector section, the intake system further comprising a throttle valve disposed in the intake passage section at an intermediate position dividing the intake passage section into an upstream intake passage subsection on an upstream side of the throttle valve and a downstream intake passage subsection extending from the throttle valve to the collector section; and
- an EGR system for returning part of the exhaust gas as EGR gas from the exhaust system into the downstream passage subsection of the intake system, the EGR system comprising an EGR gas introduction port having an EGR gas introduction opening for directing an inflow EGR gas stream into the downstream passage subsection, the EGR gas introduction opening being located downstream of a first free end of the throttle valve in a closed position, the EGR gas introduction port extending along a tangential direction tangential to a curved inside wall surface of the downstream passage subsection.
- 2. The exhaust gas recirculation system as claimed in claim 1 wherein an inflow direction of the EGR gas introduction port is inclined downstream so as to form a predetermined angle with respect to a direction of a fresh intake air stream in the downstream passage subsection.
- 3. The exhaust gas recirculation system as claimed in claim 1 wherein an inflow direction of the EGR gas introduction port extends in an imaginary cross sectional plane of the downstream passage subsection.
- 4. An engine system comprising:
- an engine;
- an exhaust system for carrying exhaust gas away from the engine;
- an intake system for supplying intake air to the engine, the intake system comprising a throttle valve disposed in an intake passage which comprises an upstream intake passage section on an upstream side of the throttle valve and a downstream intake passage section on a downstream side of the throttle valve; and
- an EGR system for returning part of the exhaust gas as EGR gas from the exhaust system into the downstream intake passage section of the intake system, the EGR system comprising an EGR introduction opening which opens into the downstream intake passage section in a predetermined EGR introducing direction to direct an inflow EGR gas stream circumferentially along a curved inside wall surface of the downstream passage section around a central region of the downstream intake passage section.
- 5. The engine system as claimed in claim 4 wherein the EGR introduction opening faces in the EGR introducing direction which extends through a circumferential annular region surrounding the central region in the downstream intake passage section without intersecting the central region which is a region in which a back flow region extends behind the throttle valve when the throttle valve is fully closed, and the EGR introduction opening is located, longitudinally along a longitudinal direction of the intake passage, between the throttle valve and a downstream end of the back flow region formed on the downstream side of the throttle valve when the throttle valve is fully closed.
- 6. The engine system as claimed in claim 4 wherein the EGR introduction opening is elongated along a longitudinal direction of the downstream intake passage section.
- 7. The engine system as claimed in claim 4 wherein the EGR introduction opening opens in the EGR introducing direction which is tangential to the curved inside wall surface of the downstream intake passage section.
- 8. The engine system as claimed in claim 7 wherein the curved inside wall surface of the downstream passage section is a cylindrical inside surface and the EGR introduction opening opens in the EGR introducing direction tangential to the cylindrical inside surface of the downstream intake passage section; and wherein the downstream intake passage section has a circular cross section, and the EGR introduction opening opens along the EGR introducing direction tangential to the circular cross section of the downstream intake passage section.
- 9. The engine system as claimed in claim 7 wherein the EGR introducing direction is parallel to an imaginary cross sectional plane of the downstream intake passage section.
- 10. The engine system as claimed in claim 7 wherein an opening area of the EGR introduction opening is determined in accordance with a maximum speed of a fresh intake air stream passing through the throttle valve, a distance from a swing axis of the throttle valve to the EGR introduction opening and a speed of an EGR gas inflow stream modified by an opening shape of the EGR introduction opening.
- 11. The engine system as claimed in claim 7 wherein the EGR introducing direction is an inclined direction which is inclined with respect to an imaginary cross sectional plane of the downstream intake passage section and which is intermediate between a non-inclined direction parallel to the imaginary cross sectional plane of the downstream intake passage section and a downstream longitudinal direction of the downstream intake passage section.
- 12. The engine system as claimed in claim 11 wherein the EGR introducing direction is a direction tangent to an imaginary helix around the longitudinal center line of the downstream intake passage section, an inclination angle between the EGR introducing direction and the imaginary cross sectional plane of the downstream intake passage section is equal to a lead angle of the helix, and a lead of the helix is smaller than a distance between the EGR introduction point and an inlet of any of the branches of the intake pipe system.
- 13. The engine system as claimed in claim 7 wherein the EGR system comprises an EGR introduction port extending in the EGR introducing direction, and having an open end defining the EGR introduction opening.
- 14. The engine system as claimed in claim 13 wherein the EGR introduction port comprises a guide case projecting along the EGR introducing direction into the downstream intake passage section, and defining the open end of the EGR introduction port.
- 15. The engine system as claimed in claim 7 wherein the EGR system comprises an EGR introduction pipe defining the EGR introduction opening for introducing the EGR gas into the downstream intake passage section, the EGR introduction pipe projects into the downstream intake passage section through a hole formed in a circumferential wall of the downstream intake passage section, and the EGR introduction pipe comprises a base side pipe section formed with the EGR introducing opening and a tip side pipe section which defines a tip end of the EGR introduction pipe and which is formed with another EGR introduction opening.
- 16. The engine system as claimed in claim 15 wherein the EGR introduction opening of the tip side pipe section is opened in the tip end of the EGR introduction pipe, and the EGR introduction pipe extends circumferentially in the downstream intake passage section along the curved inside wall surface of the downstream intake passage section.
- 17. The engine system as claimed in claim 15 wherein at least one of the EGR introduction openings is opened in an inclined direction tangential to an imaginary circular helix around a longitudinal center line of the downstream intake passage section to produce a spiral flow advancing downstream in the downstream passage section.
- 18. The engine system as claimed in claim 15 wherein the EGR introduction pipe has a streamlined outside contour to reduce a resistance to a fluid flow in the downstream intake passage section.
- 19. The engine system as claimed in claim 15 wherein the EGR introduction openings formed in the base side pipe section and tip side pipe section of the EGR introduction pipe are located at diametrically opposite positions around a longitudinal center line of the downstream intake passage section, and directed in parallel but opposite directions.
- 20. The engine system as claimed in claim 19 wherein the EGR introduction opening formed in the tip side pipe section is opened to a first EGR introduction point located behind a downstream swing end of the throttle valve which swings toward a downstream side of a swing axis of the throttle valve, and the EGR introduction opening formed in the base side pipe section is opened to a second EGR introduction point located behind an upstream swing end of the throttle valve which swings toward an upstream side of the swing axis of the throttle valve; and wherein a longitudinal distance of the EGR introduction opening formed in the base side pipe section from the swing axis of the throttle valve along a longitudinal center line of the downstream intake passage section is smaller than a longitudinal distance of the EGR introduction opening formed in the tip side pipe section from the swing axis of the throttle valve along the longitudinal center line of the downstream intake passage section.
- 21. The engine system as claimed in claim 19 wherein the tip end of the EGR introduction pipe is closed, and the EGR introduction opening of the tip side pipe section is formed in a circumferential pipe wall of the tip side pipe section.
- 22. The engine system as claimed in claim 7 wherein said EGR introduction opening is a first EGR introduction opening, said EGR introducing direction of the first EGR introduction opening is a first EGR introducing direction, and the EGR system further comprises a second EGR introduction opening which opens into the downstream intake passage section in a second predetermined EGR introducing direction to direct an inflow EGR gas stream circumferentially along the curved inside wall surface of the downstream passage section around the central region of the downstream intake passage section.
- 23. The engine system as claimed in claim 22 wherein the first EGR introduction opening is aimed at a first EGR introduction point lying behind the first swing end of the throttle valve which swings toward a downstream side of a swing axis of the throttle valve, the second EGR introduction opening is aimed at a second EGR introduction point lying behind the second swing end of the throttle valve which swings toward an upstream side of the swing axis of the throttle valve, the first and second EGR introduction points are located at diametrically opposite positions around a longitudinal center line of the downstream passage section, and the first and second EGR introduction openings are directed in an equal rotational direction around the longitudinal center line so that the first and second EGR introducing directions are substantially parallel but opposite to each other.
- 24. The engine system as claimed in claim 23 wherein a cross sectional area of the second EGR introduction opening is greater than a cross sectional area of the first EGR introduction opening.
- 25. The engine system as claimed in claim 23 wherein a distance of the second EGR opening from the throttle valve is smaller than a distance of the first EGR opening from the throttle valve.
- 26. The engine system as claimed in claim 23 wherein each of the first and second EGR introducing directions is inclined toward a downstream side to produce a spiral flow advancing downstream in the downstream passage section, and an inclination angle formed between the second EGR introducing direction and a cross sectional plane of the downstream passage section is smaller than an inclination angle formed between the first EGR introducing direction and a cross sectional plane of the downstream passage section.
- 27. The engine system as claimed in claim 23 wherein the EGR system comprises an EGR introduction pipe which is formed with the first and second EGR introduction openings and which extends, inside the downstream passage section, between a position of the first EGR introduction opening and a position of the second EGR introduction opening.
- 28. The engine system as claimed in claim 27 wherein the EGR introduction pipe projects into the downstream intake passage section through a hole formed in a circumferential wall of the downstream intake passage section and extends, inside the downstream intake passage section, in one of a diametrical direction of the downstream intake passage section, a circumferential direction around a longitudinal center line of the downstream intake passage section, and an oblique direction such that a projecting end of the EGR introduction pipe is located downstream of the hole formed in the circumferential wall of the downstream intake passage section.
- 29. The engine system as claimed in claim 7 wherein the engine comprises a plurality of cylinders, the intake system comprises an intake pipe system for distributing intake air to the cylinders of the engine, the intake pipe system comprises a collector section connected with a downstream end of the intake passage, a passage defining section defining the intake passage for conveying the intake air to the collector section, and a plurality of branches leading from the collector section, respectively, to the cylinders of the engine, the downstream intake passage section of the intake passage extends from the throttle valve to the collector section, and the EGR system comprises an EGR passage for conveying the EGR gas from the exhaust system to the EGR introduction opening.
- 30. The engine system as claimed in claim 29 wherein the EGR introduction opening is located at a first circumferential position lying at a middle of a fresh main stream flowing through a gap of a first swing end of the throttle valve and the curved inside wall surface of the downstream passage section; wherein the EGR introduction opening is opened to an EGR introduction point lying on an imaginary normal straight line which intersects an imaginary longitudinal center line of the downstream passage section and which is perpendicular to an imaginary parallel straight line extending, in parallel to a swing axis of the throttle valve, in an imaginary first center surface that is a ruled surface generated by translational motion of the swing axis of the throttle valve along the longitudinal center line of the downstream passage section; and wherein the EGR system comprises an EGR introduction port defining the EGR introduction opening which is opened in one of a tip side end of the EGR introduction port and a circumferential wall of the EGR introduction port.
- 31. The engine system as claimed in claim 29 wherein a longitudinal center line of the downstream intake passage section is straight, the EGR system comprises a first EGR introduction port lying between an imaginary first center plane containing both a swing axis of the throttle valve and the longitudinal center line of the downstream intake passage section, and a first imaginary tangent plane which is parallel to the first center plane and tangent to the inside wall surface of the downstream intake passage section which is a cylindrical surface, and the first EGR introduction port extends along the first tangent plane and having an open end defining the EGR introduction opening facing to a first EGR introduction point lying on an imaginary second center plane intersecting the first center plane at right angles along the center line of the downstream intake passage section.
- 32. The engine system as claimed in claim 31 wherein the EGR system further comprises a second gas introduction port for directing an inflow gas stream into the downstream intake passage section of the intake system, the first and second introduction ports being located on opposite sides of the first imaginary center plane, the first and second introduction ports being located, respectively, on first and second sides of the second imaginary center plane, the first introduction port extending from the first side of the second center plane and opening toward the second side of the second center plane, the second introduction port extending from the second side of the second center plane and opening toward the first side of the second center plane.
- 33. The engine system as claimed in claim 29 wherein a longitudinal direction of the downstream intake passage section and a longitudinal direction of the collector section intersect each other in a predetermined imaginary plane so as to form a bend between the downstream intake passage section and the collector section, the predetermined imaginary plane contains a swing axis of the throttle valve, and the EGR introduction opening is positioned on an outer side of the bend.
- 34. The engine system as claimed in claim 33 wherein the EGR introduction opening is an upstream EGR introduction opening which is opened to an upstream EGR introduction point located behind an upstream swing end of the throttle valve, the EGR system further comprises a downstream EGR introduction opening which is positioned on an inner side of the bend and which is opened to a downstream EGR introduction point located behind a downstream swing end of the throttle valve, and a distance of the upstream EGR opening from the swing axis of the throttle valve along the longitudinal direction of the downstream intake passage section is smaller than a distance of the downstream EGR introduction opening from the swing axis of the throttle valve along the longitudinal direction of the downstream intake passage subsection.
- 35. The engine system as claimed in claim 29 wherein a longitudinal direction of the downstream intake passage section and a longitudinal direction of the collector section intersect each other in a predetermined imaginary plane so as to form a bend between the downstream intake passage section and the collector section, the predetermined imaginary plane is perpendicular to a swing axis of the throttle valve, and the EGR introduction opening is positioned on an inner side of the bend.
- 36. The engine system as claimed in claim 35 wherein the EGR introduction opening is an upstream EGR introduction opening which is opened to an upstream EGR introduction point located behind an upstream swing end of the throttle valve, the EGR system further comprises a downstream EGR introduction opening which is positioned on an outer side of the bend and which is opened to a downstream EGR introduction point located behind a downstream swing end of the throttle valve, and a distance of the upstream EGR opening from the swing axis of the throttle valve along the longitudinal direction of the downstream intake passage section is smaller than a distance of the downstream EGR introduction opening from the swing axis of the throttle valve along the longitudinal direction of the downstream intake passage subsection.
- 37. The engine system as claimed in claim 29 wherein said EGR introduction opening is an upstream EGR introduction opening, the EGR system further comprises a downstream EGR introduction opening which opens toward a central region of the collector section.
- 38. The engine system as claimed in claim 37 wherein the EGR system comprises an upstream EGR introduction port extending in the EGR introducing direction and having an end formed with the upstream EGR introduction opening, and a downstream EGR introduction port extending in a direction to direct the EGR gas from an upstream end of the collector section toward a downstream end of the collector section and having an end formed with the downstream EGR opening which is opened to the upstream end of the collector section.
- 39. The engine system as claimed in claim 37 wherein a cross sectional area of the upstream EGR introduction opening is greater than a cross sectional area of the downstream EGR introduction opening.
- 40. The engine system as claimed in claim 29 wherein the EGR introduction opening is opened to an EGR introduction point located behind a first swing end of the throttle valve.
- 41. The engine system as claimed in claim 40 wherein the first swing end of the throttle valve is an upstream swing end of the throttle valve which swings toward an upstream side of a swing axis of the throttle valve.
- 42. The engine system as claimed in claim 41 wherein the EGR system further comprises an auxiliary air introduction opening for introducing an auxiliary intake air into the downstream intake passage section, the auxiliary air introduction opening opens to an auxiliary air introduction point lying in the downstream passage section, and auxiliary air introduction point is located behind a second swing end of the throttle valve which swings toward a downstream side of the swing axis of the throttle valve.
- 43. The engine system as claimed in claim 40 wherein the first swing end of the throttle valve is a downstream swing end of the throttle valve which swings toward a downstream side of a swing axis of the throttle valve.
- 44. The engine system as claimed in claim 43 wherein the downstream passage section comprises a deflecting rib which projects from the curved inside wall surface of the downstream passage section, and which extends between the downstream swing end of the throttle valve and the EGR introduction opening.
Priority Claims (6)
Number |
Date |
Country |
Kind |
9-142381 |
May 1997 |
JPX |
|
10-008966 |
Jan 1998 |
JPX |
|
10-012430 |
Jan 1998 |
JPX |
|
10-012431 |
Jan 1998 |
JPX |
|
10-084301 |
Mar 1998 |
JPX |
|
10-324974 |
Nov 1998 |
JPX |
|
RELATED APPLICATION
This application is a continuation-in-part of U.S. Ser. No. 09/076,489 filed on May 13, 1998, now abandoned.
US Referenced Citations (14)
Foreign Referenced Citations (5)
Number |
Date |
Country |
35 11 094 |
Oct 1986 |
DEX |
60-171952 |
Nov 1985 |
JPX |
3-114564 |
Nov 1991 |
JPX |
3-114563 |
Nov 1991 |
JPX |
8-218949 |
Aug 1996 |
JPX |
Continuation in Parts (1)
|
Number |
Date |
Country |
Parent |
076489 |
May 1998 |
|