JP2015229940A - Inlet duct - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inlet duct in which a ventilation resistance at an inside part of a bent part is reduced.SOLUTION: An inlet duct 11 has an inlet, an outlet and a bent part. A distance (an inner diameter L) between points 18, 19 where a virtual plane P including a flow passage central line of the inlet duct 11 having the bent part and a section M acting as a section of the bent part is equal to a diameter of a circular section N acting as a section other than that of the bent part. A pair of areas 20, 21 becoming inside of the bent part protrude more outward in a radial direction than that of the circular section N. An inner wall part 16 forms a curved surface with a lower curvature factor than that of an arc of the circular section N. A pair of areas 22, 23 becoming an outer side of the bent part are placed more inside in a radial direction than from the circular section N. A size of the inner diameter L and a flow passage sectional area along the virtual plane P are kept constant over the entire inlet duct 11 and in turn, as a distribution of the passage sectional area at the section M, it is enlarged more in an inside area of the bent part and it is shrunk more at the outside area of the bent part as compared with that of the circular section N.

Description

  The present invention relates to an intake duct used in an automobile engine.

  An intake duct used for an intake part of an automobile engine is used to supply outside air taken from the outside to the engine. Since the engine room is limited in space, the intake duct usually has a bent portion in order to effectively use the space. In such an intake duct, the flow of intake air is concentrated inside the bend of the bend due to the nature of the fluid passing through the shortest distance. For this reason, as the bending angle of the bent portion increases, the flow of the intake air is more easily separated downstream of the bent portion, thereby increasing the pressure loss of the intake air flowing through the duct.

  As a method for reducing the pressure loss generated in the intake duct, for example, as described in Patent Document 1, the inner wall surface of the portion located on the downstream side of the bent portion is recessed inward, and the duct in the portion is Some have a reduced cross-sectional area.

JP 2008-88834 A

  However, since the above-described intake duct does not correspond to the bent portion where the flow is concentrated, the resistance at the bent portion cannot be reduced, and the pressure loss of the intake air flowing through the duct is effectively reduced. There was still room for improvement in order to reduce it.

  The intake duct according to the present invention has a basic cross-sectional shape with a circular cross section, and the first straight portion and the second straight portion are connected via a bent portion. The bent portion has a passage cross-sectional area equal to the passage cross-sectional area of the first linear portion and the second linear portion, and the cross-sectional area of the region inside the bend is a section of the region that is outside the bend. It has an irregular cross-sectional shape larger than the area.

  In this way, the bending portion has a passage cross-sectional area equal to the passage cross-sectional area of the linear portion, and the cross-sectional area of the region that is inside the bend is made larger than the cross-sectional area of the region that is outside the bend. The resistance at the bent portion can be effectively reduced without increasing the cross-sectional area of the entire intake duct.

  In one preferred embodiment, the bent portion has a cross-sectional shape that approximates a triangle whose apex angle is directed to the outside of the bend.

  More specifically, the cross-sectional shape of the bent portion is such that the inner diameter along the direction of the bend is equal to the diameter of the circular cross-section as compared to the circular cross-sections of the first linear portion and the second linear portion. A pair of portions that are on the inside protrude from the circular cross section to the outside in the radial direction, and a pair of portions that are outside the bend enter the inside in the radial direction from the circular cross section.

  In the present invention, the intake duct may include a plurality of bent portions.

  According to the present invention, it is possible to effectively reduce the resistance at the bent portion and reduce the pressure loss of the intake air without increasing the cross-sectional area of the entire intake duct. In addition, it is possible to suppress the generation of noise caused by enlarging the duct diameter.

The perspective view of the air intake duct which concerns on this invention. The figure which shows the cross section of the bending part of the intake duct which concerns on this invention. The side view of the air intake duct which concerns on this invention which shows the position of cross section AE. The comparison figure of a circular cross section and the cross-sectional shape of the bending part which concerns on this invention. Sectional drawing which shows the flow velocity of the intake air in the cross section A. Sectional drawing which shows the flow velocity of the intake air in the cross section B. Sectional drawing which shows the flow velocity of the intake air in the cross section. Sectional drawing which shows the flow velocity of the intake air in the cross section. Sectional drawing which shows the flow velocity of the intake air in the cross section. The figure which shows the example which applied the air intake duct which concerns on this invention to the air cleaner for motor vehicles. The perspective view of the conventional intake duct. The figure which shows the cross section of the bending part of the air intake duct of FIG. The side view of the air intake duct of FIG. 11 which shows the position of cross section ae. Sectional drawing which shows the flow velocity of the intake air in the cross section a. Sectional drawing which shows the flow velocity of the intake air in the cross section b. Sectional drawing which shows the flow velocity of the intake air in the cross section c. Sectional drawing which shows the flow velocity of the intake air in the cross section d. Sectional drawing which shows the flow velocity of the intake air in the cross section e.

  First, a conventional intake duct 1 will be described with reference to FIGS. The intake duct 1 has a first straight portion 2, a second straight portion 3, and a bent portion 4 bent at a predetermined angle, and the first straight portion 2 and the second linear portion 3 are connected via a bent portion 4. One open end of the first linear portion 2 serves as the inlet 2 a of the intake duct 1, and one open end of the second straight portion 3 serves as the outlet 3 a of the intake duct 1. The bending angle of the bending portion 4 is 90 degrees. The intake duct 1 has a tubular shape with a circular cross section, and has the same cross-sectional shape from the inlet 2a to the outlet 3a. As shown in FIG. 12, the air intake duct 1 includes, in a circular cross section, an inner wall portion 6 along the inside of the bent portion 4, an outer wall portion 7 along the outside of the bent portion 4, and Is provided.

  As shown in FIG. 13, in the conventional intake duct 1, along the flow direction, the cross section of the inlet 2a is the cross section a, the cross section of the portion located downstream thereof is the cross section b, the cross section of the bent portion 4 is the cross section c, The cross section of the portion located downstream is the cross section d, the cross section of the outlet 3a is the cross section e, and the flow velocity distribution of the intake air in the cross sections a to e is shown in FIGS. 14 to 18, the left side of the figure is the inner wall part 6 along the inside of the bent part 4 of the intake duct 1, and the right side of the figure is the outer wall part 7 along the outside of the bent part 4. . In these figures, the region with the fastest flow rate is designated as S1, the region with the slowest flow rate is designated as S9, and the region of the flow velocity of intake air in each cross section is divided into nine stages from S1 to S9 (see FIG. 14). ing.

  In the cross section a shown in FIG. 14, the flow velocity of the intake air is the fastest at the central portion of the intake duct 1, decreases toward the outer periphery, and is the slowest at the outer peripheral portion. That is, in the cross section a, the flow rate of the intake air is concentrated in the central portion of the intake duct 1.

  On the other hand, as shown in FIG. 15, in the cross section b serving as the inlet portion of the bent portion 4, the flow velocity in the portion near the inner wall portion 6 of the intake duct 1 increases, and conversely, the outer wall portion 7 The flow velocity in the near part is decreasing.

  In the cross section c shown in FIG. 16, the flow velocity is further increased in a region close to the inner wall portion 6 of the bent portion 4 as compared with the cross section b, and the outer wall of the bent portion 4 particularly in the portion outside the bend. The flow velocity decreases in the area close to the portion 7. That is, in the cross section c, the flow rate of the intake air is concentrated on the inner part of the intake duct 1 and is greatly reduced in the outer part.

  In the cross section d shown in FIG. 17, the flow velocity of the intake air is slightly slower in the inner portion of the intake duct 1 and faster in the central portion. Further, in the cross section e shown in FIG. 18, the flow velocity of the intake air is faster at the portion outside the bend than the portion inside the bend of the intake duct 1.

  Thus, in the conventional air intake duct 1 having a circular cross section, the flow tends to flow from the inlet 2a to the outlet 3a at the shortest distance, so that the flow is concentrated inside the bend at the bent portion 4. As a result, the flow rate of the entire intake duct 1 is limited at the bent portion 4.

  Next, an embodiment of an intake duct according to the present invention will be described with reference to FIGS. The intake duct 11 includes a first linear portion 12, a second linear portion 13, and a bent portion 14 bent at a predetermined angle, and the first linear portion 12 and the second linear portion 13 are connected via a bent portion 14. One open end of the first linear portion 12 serves as the inlet 12 a of the intake duct 11, and one open end of the second linear portion 13 serves as the outlet 13 a of the intake duct 11. In this embodiment, the bending angle of the bending portion 14 is 90 degrees. As shown in the drawing, the cross section of the intake duct 11 is circular at the inlet 12a and the outlet 13a, but the bent portion 14 is a cross sectional shape approximated to a triangle whose apex angle is directed to the outside of the bent as shown in FIG. have. Thus, although the cross-sectional shape is different between the bent portion 14 and the inlet 12a and the outlet 13a, the cross-sectional areas of the bent portion 14 are the same as the cross-sectional areas of the inlet 12a and the outlet 13a.

  As shown in FIG. 3, with respect to the intake duct 11, along the flow direction, the cross section of the inlet 12a is the cross section A, the cross section of the portion located downstream thereof is the cross section B, the cross section of the central portion of the bent portion 14 is the cross section C, A cross section of a portion located downstream thereof is referred to as a cross section D, and a cross section of the outlet 13a is referred to as a cross section E. Hereinafter, cross sections A to E will be described. In addition, the cross section B and the cross section D correspond to the boundary on the inlet side and the outlet side of the bent portion 14 and the linear portions 12 and 13 that are bent at 90 °, respectively.

  FIG. 4 is a diagram in which the central cross section (cross section C) of the bent portion 14 of the embodiment is compared with the circular cross section (cross section A and the like), and the cross-sectional shape of the passage of the bent portion 14 of the embodiment is indicated by a solid line M. The cross-sectional shape of a circular passage other than the bent portion 14 is indicated by a broken line N. In the figure, the plane P shows a virtual plane including the flow path center line of the intake duct 11 having the bent portion 14. That is, the intake duct 11 extends while being curved along the plane P. As shown in the figure, the two points 18 and 19 where the substantially triangular cross section M intersects the plane P coincide with the circular cross section N. In other words, the inner diameter L (the distance L between the two points 18 and 19 along the direction of bending) along the plane P of the cross section M is equal to the diameter of the circular cross section N.

  A pair of regions 20 and 21 (regions on both sides sandwiching the point 18) inside the bend at the bent portion 14 protrude outward in the radial direction from the circular cross section N, and extend along the inside of the bend in the vicinity of the point 18. The inner wall portion 16 has a curved surface close to a flat surface having a gentler curvature than the circular arc of the circular cross section N. On the other hand, the pair of regions 22 and 23 (regions on both sides sandwiching the point 19) that are outside the bend enter the inside in the radial direction from the circular cross section N, and the outer wall portion 17 along the outside of the bend. As a whole, it has a shape close to a mountain shape with the point 19 as a vertex. In other words, the bent portion 14 has an irregular cross-sectional shape in which the cross-sectional area of the region that is inside the bend is larger than the cross-sectional area of the region that is outside the bend.

  As described above, as a result of the pair of regions 20 and 21 projecting outward in the radial direction and the pair of regions 22 and 23 entering inward in the radial direction, the passage cross-sectional area distribution of the cross section M is compared with the circular cross section. Thus, it is enlarged in the area inside the bend and reduced in the area outside the bend.

  Between the cross-section C and the cross-sections B and D, the above-described regions 20, 21, 22, and 23 are gradually deformed while keeping the inner diameter L between the points 18 and 19 constant. Transitioning smoothly to D.

  As described above, in the intake duct 11 of the above embodiment, the dimension of the inner diameter L along the plane P and the cross-sectional area of the passage are constant over the entire intake duct including the linear portions 12 and 13 and the bent portion 14. In addition, the distribution of the passage cross-sectional area in the bent portion 14 is enlarged inside the bend. As described above, the flow of the intake air flowing from the inlet 12a toward the outlet 13a is offset toward the inner side of the bend in the bent portion 14 so as to flow through the shortest distance. Therefore, the cross-sectional shape of the passage of the bent portion 14 is substantially the same as described above. By adopting a triangular shape, the passage resistance is reduced and a larger flow rate can be obtained.

  5 to 9 show the flow velocity distribution of the intake air in the cross section A to the cross section D of the intake duct 11 according to the present invention. 5 to 9, the left side of the figure is the inner wall part 16 along the inside of the bent part 14 of the intake duct 11, and the right side of the figure is the outer wall along the outside of the bent part 14. Part 17. In these figures, the region where the flow velocity is the fastest is S1, the region where the flow velocity is the slowest is S9, and the flow velocity region of the intake air in each cross section is divided into nine stages from S1 to S9 (see FIG. 5). ing.

  In the cross section A shown in FIG. 5, the flow velocity of the intake air is the fastest at the central portion of the intake duct 11 and the slowest at the outer peripheral portion. On the other hand, as shown in FIG. 6, in the cross section B serving as the inlet portion of the bent portion 14, the flow velocity in the portion near the inner wall portion 16 of the intake duct 11 increases, and conversely, the outer wall portion 17 The flow velocity in the near part is decreasing.

  As shown in FIG. 7, in the cross section C, compared with the circular cross section B, the flow velocity further increases in a region close to the inner wall portion 16 of the bent portion 14. However, the region (S1) having the fastest flow velocity is compared with the region (S1) having the fastest flow velocity in the circular cross section c of the bent portion 4 shown in FIG. 16 by enlarging the cross-sectional area of the portion inside the bend. It has decreased significantly. On the other hand, in the portion that is outside the bend of the bent portion 14, the flow velocity is reduced in a region close to the outer wall portion 17 as compared with the circular cross section B. The region where the flow velocity is low is narrower than the circular cross section c of the bent portion 4 shown in FIG. 16 due to the reduced cross-sectional area of the portion outside the bend.

  In the cross section D shown in FIG. 8, the flow velocity of the intake air is slightly slow on the inner wall portion 16 side of the intake duct 11 and is fast at the central portion. Further, in the cross section E shown in FIG. 9, the flow velocity of the intake air is faster on the outer wall 17 side than on the inner wall 16 side of the intake duct 11.

  Thus, in the said Example, since the flow velocity of the inner area | region of the bending in the bending part 14 falls and the raise of ventilation resistance is suppressed, the increase in flow volume can be aimed at. According to the above embodiment, when the cross-sectional area of the bent portion 14 having the cross-sectional shape shown in FIG. 7 is the same as that of the conventional bent portion 4 having a circular cross section, the effect of reducing the airflow resistance by about 10% is obtained. It was.

  Next, a more specific configuration example in which the air intake duct 11 according to the present invention is applied to an automobile air cleaner 20 will be described with reference to FIG. The air cleaner 20 includes a case main body 22, a filter element 24, and a cover 26. One end of an outside air introduction duct 25 is connected to an intake port provided on one side wall of the case body 22. On the other hand, the intake duct 11 is connected to an intake outlet provided on one side wall of the cover 26. The intake duct 11 has a plurality of bent portions 14 and is curved so as to form an elongated substantially S shape.

  In the present embodiment, the intake duct 11 has three bent portions 14a to 14c. The first bent portion 14a located on the most upstream side and the second bent portion 14b located on the downstream side thereof have a bend angle of about 60 degrees. Further, the third bent portion 14c located downstream has a bend angle of about 180 degrees and is substantially U-shaped. The central cross sections of these bent portions 14a to 14c are all substantially triangular as shown in FIGS. 4 and 7 corresponding to the direction of each bend.

  During operation of the engine, air flows into the air cleaner 20 through the outside air introduction duct 25 and the intake port, and passes through the filter element 24 to remove dust. The air from which the dust has been removed flows out of the air cleaner 20 through the intake outlet and flows into the intake duct 11, and sequentially passes through the first bent portion 14a, the second bent portion 14b, and the third bent portion 14c. Thus, the air flows from the intake duct 11 to an engine outside the figure. At this time, each of the bent portions 14a to 14c has a ventilation resistance. However, as described above, the passage resistance is reduced by enlarging the cross-sectional area of the bent portions 14a to 14c, so that it is simple. A larger flow rate can be obtained compared to a circular cross section.

  Therefore, the flow rate can be increased by effectively reducing the resistance at the bent portion without increasing the cross-sectional area of the entire intake duct.

  Furthermore, according to the above-described embodiment, since the resistance in the bent portion 14 can be reduced without increasing the cross-sectional area of the entire intake duct, it is possible to suppress the generation of noise caused by increasing the duct diameter. Can do.

  As mentioned above, although one Example of this invention was described, this invention is not restricted to the said Example, A various change is possible.

  In the illustrated embodiment, the cross-sectional shape of the bent portion 14 is substantially triangular, but the present invention is not necessarily limited to a specific shape as shown in FIG. Moreover, the bending angle of the bending part 14 is not limited to the said Example, It is good also as another angle.

DESCRIPTION OF SYMBOLS 11 Intake duct 12 1st linear part 12a Inlet 13 2nd linear part 13a Outlet 14 Bending part 16 Inner side wall part 17 Outer side wall part

Claims (4)

In an intake duct of an engine having a basic cross-sectional shape having a circular cross section and having a first linear portion and a second linear portion connected via a bent portion,
The bend is
A passage cross-sectional area equal to the passage cross-sectional area of the first linear portion and the second linear portion;
An intake duct having an irregular cross-sectional shape in which a cross-sectional area of a region on the inside of the bend is larger than a cross-sectional area of a region on the outside of the bend.   The intake duct according to claim 1, wherein the bent portion has a cross-sectional shape that approximates a triangle whose apex angle is directed to the outside of the bend.   The cross-sectional shape of the bent portion is equal to the inner diameter of the circular cross section, and the inner diameter along the direction of the bend is equal to the circular cross section of the first linear portion and the second linear portion. 3. The air intake duct according to claim 2, wherein the pair of portions protrudes radially outward from the circular cross section, and the pair of portions that are outside of the bending enter the radial inner side from the circular cross section.   The intake duct according to claim 3, wherein the intake duct includes a plurality of bent portions.

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