Engine intake system

Abstract

To provide a suction device for an engine capable of suppressing deviation of condensate water in a surge tank to suppress accidental fire resulting from the condensate water.SOLUTION: A suction device for an engine comprises a suction manifold 6. The suction manifold 6 has a plurality of runners, a surge tank 62 and a suction introduction passage 61. The surge tank 62 has a space where the plurality of runners are gathered, and is provided so that runner introduction ports 63b, 64b, 65b, 66b of each of the plurality of runners are arranged along a predetermined direction. The suction air introduction passage 61 is a passage for introducing air into the surge tank 62. A lower wall inner surface 62a of the surge tank 62 is provided with ribs 62b to 62d extending from portions 62e to 62g between the adjacent runner introduction ports 63b, 64b, 65b, 66b toward the inner surfaces of side walls facing each other across the space.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to an intake system for an engine. [Background technology]

[0002] Some vehicle engines are equipped with an EGR (Exhaust Gas Recirculation) device that recirculates part of the exhaust gas back into the intake air. By adding an EGR device like this, it is possible to suppress an excessive rise in the combustion gas temperature, suppress the generation of nitrogen oxides (NOx), and reduce pumping losses during intake.

[0003] The fresh air and EGR gas sent from the intake manifold to each cylinder of the engine contain moisture. This moisture can accumulate as condensed water in the surge tank of the intake manifold. If this accumulated condensed water is sent to a specific cylinder, it may cause a misfire in that cylinder.

[0004] Patent Document 1 discloses an intake manifold that has a receiving portion provided at the inlet of the surge tank to receive condensed water, and a guide surface portion provided inside the surge tank to guide the received condensed water in the direction of cylinder alignment and gradually drip it. By adopting the above-mentioned configuration, the intake manifold disclosed in Patent Document 1 attempts to prevent condensed water from being sent to a specific cylinder. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-286069 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the technology disclosed in Patent Document 1 above may cause uneven distribution of condensed water in the surge tank due to the flow of fresh air and EGR gas, and is therefore not sufficient to prevent a large amount of condensed water from being sent to a specific cylinder all at once.

[0007] Furthermore, since the fresh air taken into the intake manifold also contains moisture, it is conceivable that the same problem of misfires occurring due to condensed water being sent to specific cylinders could occur even in engines that do not have an EGR device.

[0008] An object of the present invention is to provide an intake device for an engine that can suppress misfires caused by condensed water by suppressing uneven distribution of condensed water in a surge tank. [Means for solving the problem]

[0009] According to one aspect of the present invention, there is provided an intake system for an engine, comprising an engine body and an intake manifold. The engine body has a cylinder head with a plurality of cylinders and an intake port formed therein, which is connected to each of the plurality of cylinders. The intake manifold allows air to pass through to the plurality of intake ports in the engine body.

[0010] The intake manifold has a plurality of independent intake passages, a surge tank, and an intake introduction passage. The plurality of independent intake passages are aligned along the cylinder row direction in the engine body and are connected to each of the plurality of intake ports. The surge tank has a space where the plurality of independent intake passages are gathered, and is a portion provided so that the openings of the plurality of independent intake passages are aligned in a predetermined direction. The intake introduction passage is a passage that introduces air into the surge tank.

[0011] In the engine intake device of this aspect, the surge tank has a rib on the inner surface of the lower wall of the surge tank, which rib extends from a portion between at least two adjacent openings among the plurality of openings toward the inner surface of the side wall opposite the side wall in which the plurality of openings are provided, with the space therebetween. In the engine intake device according to this aspect, the plurality of openings are provided so that their lower end portions are positioned above the inner surface of the lower wall of the surge tank. In the engine intake system according to this aspect, each of the plurality of independent intake passages has a portion that extends upward from the opening. Furthermore, in the engine intake device of this aspect, the rib is connected to each of the inner surface of the lower wall, the inner surface of the side wall in which the multiple openings are provided, and the inner surface of the opposing side wall.

[0012] In the engine intake system according to the above aspect, the ribs provided on the inner surface of the lower wall of the surge tank restrict the movement of condensed water in the predetermined direction. This prevents the condensed water accumulated on the inner surface of the lower wall of the surge tank from being concentrated downstream in the air flow direction in the surge tank, thereby preventing misfires caused by a large amount of condensed water being introduced into a specific cylinder all at once. Furthermore, in the engine intake system according to the above aspect, the openings of the independent intake passages are positioned higher than the inner surface of the lower wall of the surge tank, which prevents condensed water from undesirably flowing from the surge tank into the independent intake passages when the engine is stopped, thereby preventing misfires in specific cylinders when the engine is restarted. Furthermore, in the engine intake system according to the above aspect, since each of the independent intake passages has an upwardly extending portion, condensed water remaining in the independent intake passages is returned to the surge tank when the engine is stopped, which is more suitable for preventing misfires in specific cylinders when the engine is restarted.

[0013] In the engine intake device according to the above aspect, the intake introduction passage may be formed to extend from one end of the surge tank to the other end along the predetermined direction, and may be connected to the space in the surge tank at the other end, and the intake introduction passage and the space in the surge tank may be separated by a partition wall except for the connecting portion at the other end.

[0014] In the engine intake device according to the above aspect, a partition is provided between the intake air introduction passage and the space in the surge tank, so the passage length of the intake air introduction passage can be secured, but the air flow within the surge tank tends to cause condensed water to become biased downstream in the direction of the air flow.

[0015] However, in the engine intake device according to the above aspect, the ribs provided on the inner surface of the lower wall of the surge tank can suppress uneven distribution of condensed water, making the engine intake device according to the above aspect suitable for suppressing misfires in specific cylinders caused by condensed water.

[0016] In the engine intake device according to the above aspect, a plurality of the ribs may be provided so as to extend from between adjacent ones of the openings.

[0017] In the engine intake system according to the above aspect, the plurality of ribs extending from the portions between the openings of the plurality of independent intake passages can limit the amount of condensed water introduced into each of the plurality of independent intake passages, making the engine intake system according to the above aspect even more suitable for suppressing misfires in specific cylinders due to condensed water.

[0018] In the engine intake device according to the above aspect, the intake introduction passage may be connected to the space of the surge tank in a central portion in the specified direction so as to be oriented toward the inner surface of the lower wall at the portion communicating with the space of the surge tank, and two ribs may be provided on both sides of the portion where the intake introduction passage communicates with the space in the specified direction.

[0019] In the engine intake device according to the above aspect, the intake air introduction passage is connected to the space in the surge tank at the center in the predetermined direction so as to be directed toward the inner surface of the lower wall of the surge tank, so that the air introduced into the surge tank from the intake air introduction passage hits the inner surface of the lower wall of the surge tank at the center and is deflected to both sides in the predetermined direction. When air flows from the center of the surge tank to both sides in the predetermined direction in this way, the condensed water accumulated on the inner surface of the lower wall of the surge tank also tries to move to both sides of the surge tank in the predetermined direction.

[0020] However, in the engine intake device according to the above aspect, two ribs are provided on both sides of the central portion on the inner surface of the lower wall of the surge tank, and the movement of condensed water is restricted by the ribs. Therefore, in the engine intake device according to the above aspect, it is possible to prevent the condensed water from being concentrated at both end portions of the surge tank in the predetermined direction, and to prevent a large amount of condensed water from being introduced all at once into the independent intake passages having openings near the both end portions.

[0021] In the engine intake device according to the above aspect, the intake manifold may be configured by joining a plurality of members including a first member and a second member that are joined together in the direction in which the ribs extend to form the space of the surge tank.

[0022] In the engine intake device according to the above aspect, the intake manifold is formed by joining multiple components including a first component and a second component, so that it is possible to easily manufacture an intake manifold with a complex internal structure having ribs on the inner surface of the lower wall of the surge tank.

[0027] In the intake system for the engine according to the above aspect, an EGR passage for introducing EGR gas may be connected to the intake manifold.

[0028] In the engine intake system according to the above aspect, the EGR passage is connected to the intake manifold, so excessive increases in combustion gas temperature can be suppressed, suppressing the generation of nitrogen oxides (NOx) and reducing pumping loss during intake. Meanwhile, moisture contained in the EGR gas condenses and condensed water generated from the EGR gas accumulates on the inner surface of the lower wall of the surge tank, but by providing ribs on the inner surface of the lower wall of the surge tank as described above, uneven distribution of condensed water can be suppressed, and misfires can be suppressed in specific cylinders. [Effects of the Invention]

[0029] In the engine intake device according to each of the above aspects, misfires caused by condensed water can be suppressed by suppressing uneven distribution of condensed water in the surge tank. [Brief explanation of the drawings]

[0030] [Figure 1] 1 is a schematic diagram showing the configuration of an engine according to a first embodiment. FIG. [Figure 2] FIG. 2 is a perspective view showing the external configuration of an intake manifold. [Figure 3] FIG. 2 is a perspective view showing the external configuration of an intake manifold. [Figure 4] FIG. 4 is a cross-sectional view showing the configuration of a cross section taken along line IV-IV in FIG. [Figure 5] FIG. 3 is a cross-sectional view showing the configuration of a cross section taken along line VV in FIG. [Figure 6] FIG. 2 is a perspective view showing a configuration of a base member. [Figure 7] FIG. 2 is a perspective view showing the configuration of a center member. [Figure 8] FIG. 1(a) is a schematic diagram showing the air flow and the state of condensed water in an intake manifold according to an embodiment, and FIG. 1(b) is a schematic diagram showing the air flow and the state of condensed water in an intake manifold according to a comparative example. [Figure 9] 10 is a graph showing the cumulative displacement of each cylinder in each of an example and a comparative example. [Figure 10] 1 is a graph showing the overall pressure loss in each of an example, a modified example, and a comparative example. [Figure 11] FIG. 10 is a top view showing the external configuration of an intake manifold of an engine according to a second embodiment. [Figure 12] FIG. 10 is a side view showing the external configuration of an intake manifold of an engine according to a second embodiment. [Figure 13] FIG. 2 is an exploded perspective view showing the configuration of the intake manifold, and ribs and deflection base portions provided on the inner surface of the lower wall of the surge tank. DETAILED DESCRIPTION OF THE INVENTION

[0031] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that the embodiment described below is an example of the present invention, and the present invention is not limited to the following embodiment except for its essential configuration.

[0032] [First embodiment] 1. Engine 1 Configuration The configuration of an engine 1 according to the first embodiment will be described with reference to Fig. 1. The engine 1 shown in Fig. 1 is an engine mounted on a vehicle, and some of the configuration is not shown in Fig. 1.

[0033] 1, the engine 1 includes an engine body 2, an intake device 3, an exhaust device 4, a turbocharger 5, an HP-EGR (High Pressure Exhaust Gas Recirculation) unit 8, and an LP-EGR (Low Pressure Exhaust Gas Recirculation) unit 9. The engine body 2 has a plurality of cylinders 2a (for example, four cylinders).

[0034] The intake system 3 has an intake passage 30, an air cleaner 31, an intercooler 32, a throttle valve 33, and an intake manifold 6. The intake passage 30 is connected to the intake manifold 6 via the air cleaner 31, the intercooler 32, the throttle valve 33, and the compressor 51 of the turbocharger 5. As shown by arrow A1, fresh air (air) is taken in by the air cleaner 31, pressurized by the compressor 51, cooled by the intercooler 32, and sent from the throttle valve 33 to the intake manifold 6. Note that with regard to the intake passage 30, the portion upstream of the compressor 51 in the flow direction of the fresh air may be referred to as an upstream section 30a, and the portion downstream of the compressor 51 may be referred to as a downstream section 30b.

[0035] The intake manifold 6 has an intake introduction passage 61, a surge tank 62, and a plurality of runners (independent intake passages) 62-66. One end of the intake introduction passage 61 is connected to the intake passage 30 via the throttle valve 33, and the other end is connected to the space in the surge tank 62. One end of each of the plurality of runners 63-66 is connected to the space in the surge tank 62, and the other end is connected to an intake port formed in the cylinder head of the engine body 2. The detailed structure of the intake manifold 6 will be described later.

[0036] The exhaust system 4 includes an exhaust manifold 7, an exhaust passage 40, and a silencer 41. One end of the exhaust manifold 7 is connected to an exhaust port formed in a cylinder head of the engine body 2, and the other end is connected to the exhaust passage 40. The exhaust passage 40 connects the exhaust manifold 7 and the silencer 41 via a turbine 52 of the turbocharger 5. Exhaust gas discharged from the exhaust port of the engine body 2 applies a rotational driving force to the turbine 52, and then has its pressure and temperature reduced by the silencer 41 before being discharged to the outside (arrow A2). Note that with respect to the exhaust passage 40, the portion upstream of the turbine 52 in the flow direction of the exhaust gas may be referred to as an upstream section 40a, and the portion downstream of the turbine 52 may be referred to as a downstream section 40b.

[0037] The HP-EGR section 8 has an EGR passage 81 and an EGR valve 82. One end of the EGR passage 81 is connected to an exhaust port formed in the cylinder head of the engine body 2, and the other end is connected to the intake air introduction passage 61 of the intake manifold 6. In this embodiment, the other end of the EGR passage 81 is connected to the intake air introduction passage 61 of the intake manifold 6, but it may also be connected to a portion between the intercooler 32 and the throttle valve 33 in the downstream portion 30b of the intake passage 30.

[0038] The EGR valve 82 adjusts the amount of exhaust gas that is recirculated from the exhaust port of the engine body 2 to the intake introduction passage 61 .

[0039] The LP-EGR section 9 has an EGR passage 91, an EGR cooler 92, and an EGR valve 93. The EGR passage 91 is provided to connect the downstream portion 40b of the exhaust passage 40 and the upstream portion 30a of the intake passage 30. The EGR cooler 92 is provided to cool the exhaust gas flowing through the EGR passage 91. The EGR valve 93 adjusts the amount of exhaust gas that is recirculated from the downstream portion 40b of the exhaust passage 40 to the upstream portion 30a of the intake passage 30.

[0040] 2. Configuration of intake manifold 6 The configuration of the intake manifold 6 will be described with reference to FIGS.

[0041] As shown in Figures 2 and 3, the intake manifold 6 is formed by joining a base member (first member) 6A, a center member (second member) 6B, and a cover member 6C. In this embodiment, the base member 6A, the center member 6B, and the cover member 6C are each formed from a resin material. Note that the number of members constituting the intake manifold 6, as well as the shapes and materials of each member, can be changed as appropriate.

[0042] The intake air introduction passage 61 is formed by a cylindrical pipe, and has an opening (inlet) 61a at one end to which the throttle valve 33 is connected. As shown in Figures 4 and 5, the other end of the intake air introduction passage 61 is connected to the space in the surge tank 62. The intake air introduction passage 61 and the space in the surge tank 62 are separated by a partition wall 61b, except for the above-mentioned communicating portion.

[0043] 2 to 5, the surge tank 62 is disposed below the portion where the intake air introduction passage 61 is formed. Then, as shown in FIGS. 4 and 5, the partition wall 61b is provided so as to separate the intake air introduction passage 61 and the space of the surge tank 62 in the vertical direction.

[0044] As shown in Fig. 2, the four runners 63 to 66 are each formed to extend in the vertical direction and are arranged in the direction in which the intake air introduction passage 61 extends. As shown in Fig. 3, the upper parts of the runners 63 to 66 are arranged to cover the upper part of the intake air introduction passage 61, and runner outlets 63a, 64a, 65a, and 66a are provided at the ends thereof and connected to intake ports formed in the cylinder head of the engine body 2.

[0045] As shown in Fig. 4, each of the runners 63 to 66 has, at its lower part, runner inlet ports 63b, 64b, 65b, and 66b that open toward the surge tank 62. Note that the runner inlet ports 63b, 64b, 65b, and 66b of the runners 63 to 66 correspond to "openings in a plurality of independent intake passages," and the direction in which the runner inlet ports 63b, 64b, 65b, and 66b shown in Fig. 4 are aligned corresponds to the "predetermined direction."

[0046] 2 and 5, each of the runners 63 to 66 has a portion extending upward from the runner inlets 63b, 64b, 65b, and 66b. Also, as shown in FIGS. 4 and 5, the lower end portion of each of the runner inlets 63b, 64b, 65b, and 66b is provided so as to be positioned above the lowest height level of the lower wall inner surface 62a of the surge tank 62.

[0047] 4, the dimension of the internal space of surge tank 62 in the predetermined direction (the direction in which runner inlets 63b, 64b, 65b, and 66b are aligned) is longer than the dimensions in the vertical and width directions (directions perpendicular to the paper surface of FIG. 4). The lower wall inner surface 62a of surge tank 62 is provided parallel to the predetermined direction.

[0048] As shown in Fig. 4, a rib 62b is formed along the lower-wall inner surface 62a from a portion (interval) 62e between the runner inlet 63b and the runner inlet 64b toward the front side of the paper in Fig. 4. Similarly, a rib 62c is formed along the lower-wall inner surface 62a from a portion (interval) 62f between the runner inlet 64b and the runner inlet 65b toward the front side of the paper in Fig. 4, and a rib 62d is formed along the lower-wall inner surface 62a from a portion (interval) 62g between the runner inlet 65b and the runner inlet 66b toward the front side of the paper in Fig. 4. In this embodiment, the heights of the ribs 62b to 62d from the lower-wall inner surface 62a are the same for all three ribs 62b to 62d. However, the heights of the three ribs 62b to 62d may be different from each other.

[0049] As shown in Fig. 5, the surge tank 62 has a platform-shaped deflection table 62i formed at the bottom of the inner side wall surface 62h of the side tank 62, which faces the runner inlets 63b, 64b, 65b, and 66b. The deflection table 62i is provided to correspond to (cover) the entire portion of the side wall surface 62h facing the runner inlets 63b, 64b, 65b, and 66b in the predetermined direction (the direction perpendicular to the plane of Fig. 5). The deflection table 62i deflects the air mixed within the surge tank 62 so that it passes above the lowest part of the inner side wall surface 62a of the side tank 62h and is guided to the runner inlets 63b, 64b, 65b, and 66b (arrow B).

[0050] 3. Formation of surge tank 62 by joining base member 6A and center member 6B As described above, in this embodiment, the intake manifold 6 is constructed by joining the base member 6A, the center member 6B, and the cover member 6C, and of these, the base member 6A and the center member 6B form the surge tank 62. The formation of the surge tank 62 by joining the base member 6A and the center member 6B will be described using Figures 6 and 7.

[0051] 6, the base member 6A has a portion that forms part of the intake air introduction passage 61 and a portion that forms part of the surge tank 62. As shown in FIG. 6, when the center member 6B is not joined to the base member 6A, the internal space of the base member 6A is open toward the front side of the page.

[0052] The base member 6A is formed with the entire deflection base portion 62i, base side portions 62b1, 62c1, and 62d1 which are parts of the longitudinal directions of the ribs 62b, 62c, and 62d, and a base side portion 61b1 which is part of the partition wall 61b that separates the intake air introduction passage 61 from the surge tank 62. The base member 6A including these portions 61b1, 62i, 62b1, 62c1, and 62d1 is integrally formed from a resin material.

[0053] 7, the center member 6B has a portion that forms the remaining portion of the intake air introduction passage 61 and a portion that forms the remaining portion of the surge tank 62. As shown in FIG. 7, when the base member 6A is not joined to the center member 6B, the internal space of the center member 6B is also open toward the front side of the page.

[0054] The center member 6B is formed with center-side portions 62b2, 62c2, 62d2, which are the remaining longitudinal portions of the ribs 62b, 62c, 62d, and a center-side portion 61b2, which is the remaining portion of the partition wall 61b that separates the intake air introduction passage 61 from the surge tank 62. When the base member 6A and the center member 6B are joined together, the end faces of these portions 61b2, 62b2, 62c2, 62d2 are joined to the end faces of the base-side portions 61b1, 62b1, 62c1, 62d1 of the base member 6A.

[0055] The center member 6B has runner inlets 63b, 64b, 65b, and 66b.

[0056] Similarly, the entire center member 6B, including the center-side portions 61b2, 62b2, 62c2, and 62d2, is integrally formed from a resin material.

[0057] 4. Ribs 62b to 62d prevent uneven distribution of condensed water In this embodiment, by providing ribs 62b to 62d on the surge tank 62 of the intake manifold 6, it is possible to suppress uneven distribution of condensed water due to air flow. This will be explained using Figures 8 and 9. Note that Figure 8(a) schematically shows the state of air flow and condensed water in an intake manifold 6 having the same configuration as this embodiment, and Figure 8(b) schematically shows the state of air flow and condensed water in an intake manifold 900 according to a comparative example in which the surge tank 962 does not have ribs.

[0058] 8(a), in the intake manifold 6 according to the embodiment, three ribs 62b to 62d are provided on the inner surface 62a of the lower wall of the surge tank 62. The height positions of the peaks 62j to 62l of the ribs 62b to 62d are determined based on the estimated amount of condensed water that will accumulate in the surge tank 62, which is determined at the design stage of the intake manifold 6.

[0059] Here, the four runner inlets 63b, 64b, 65b, and 66b are referred to as the #1 runner inlet 63b, the #2 runner inlet 64b, the #3 runner inlet 65b, and the #4 runner inlet 66b, in that order from the side where the inlet 61a (not shown in Figure 8(a)) of the intake air introduction passage 61 is located (the left side of the paper in Figure 8(a)).

[0060] 8(a), when the engine body 2 is running, fresh air and EGR gas (hereinafter referred to as "fresh air, etc.") are introduced (arrow C1) into the surge tank 62 through the intake air introduction passage 61. In this case, because a partition wall 61b is provided in a portion between the intake air introduction passage 61 and the surge tank 62, the fresh air and EGR gas are mixed and sent to the side of the surge tank 62 where the #4 runner introduction port 66b is provided.

[0061] In the space inside the surge tank 62, fresh air, etc. sent to the side where the #4 runner inlet 66b is provided is reversed in direction at the bottom of the surge tank 62 on the inner wall surface of the surge tank 62 toward the side where the #1 runner inlet 63b is provided. Then, the reversed fresh air, etc. is sent toward the #1 runner inlet 63b above the surface of the condensed water LQ accumulated on the inner surface 62a of the lower wall of the surge tank 62 (arrow C3). The fresh air, etc. sent in the direction of arrow C3 is introduced into the #4 runner inlet 66b, the #3 runner inlet 65b, the #2 runner inlet 64b, and the #1 runner inlet 63b (arrow C2).

[0062] 8(a), in this embodiment, ribs 62b to 62d are provided on the inner surface 62a of the lower wall of the surge tank 62, so that even if fresh air or the like flows as shown by arrow C3, the condensed water LQ is prevented from being concentrated on the side where the #1 runner inlet 63b is provided. This prevents a large amount of condensed water LQ from being sent all at once to the #1 runner inlet 63b or the #2 runner inlet 64b, thereby preventing a situation in which the corresponding cylinder 2a in the engine body 2 misfires.

[0063] 8(b), in the intake manifold 900 according to the comparative example, when the engine body is running, fresh air and the like are introduced into the surge tank 962 through the intake air introduction passage 961 (arrow C4). In the comparative example, a partition wall 961b is also provided in a portion between the intake air introduction passage 961 and the surge tank 962, so that the fresh air and the like are sent to the side of the surge tank 962 where the #4 runner introduction port 966b is provided.

[0064] In the space inside the surge tank 962, fresh air and the like sent to the side where the #4 runner inlet 966b is provided is reversed in direction at the bottom of the surge tank 962 on the inner wall surface of the surge tank 962 toward the side where the #1 runner inlet 963b is provided on the side. Then, the reversed fresh air and the like are sent toward the side where the #1 runner inlet 963b is provided (the left side of the paper in FIG. 8(b)) together with condensed water LQ that has accumulated on the inner surface 962a of the lower wall of the surge tank 962 (arrows C6 and C7). The fresh air and the like sent in the direction of arrow C6 is introduced into the #4 runner inlet 966b, the #3 runner inlet 965b, the #2 runner inlet 964b, and the #1 runner inlet 963b (arrow C5).

[0065] In the comparative example, no ribs are provided on the inner surface of the lower wall of the surge tank 962, so that the condensed water LQ is concentrated on the side where the #1 runner inlet 963b is provided due to fresh air, etc. For this reason, a large amount of condensed water LQ may be sent all at once to the #1 runner inlet 963b or the #2 runner inlet 964b, which may cause misfires in the corresponding cylinders in the engine body.

[0066] The amount of condensed water introduced into the #1 to #4 runner inlets was investigated for each of the example and the comparative example, as shown in Fig. 9. In the graph shown in Fig. 9, the amount of condensed water LQ introduced from the #1 runner inlet 963b in the comparative example is expressed as a relative value, with the amount being set to "100".

[0067] 9, in the comparative example, the amount of condensed water LQ introduced from the #1 and #2 runner inlets 963b and 964b is greater than the amount of condensed water LQ introduced from the #3 and #4 runner inlets 965b and 966b. In particular, the amount of condensed water LQ introduced from the #1 runner inlet 963b is more than 10 times the amount of condensed water LQ introduced from the #4 runner inlet 966b, as shown by arrow D2.

[0068] 9, in the embodiment, although the amount of condensed water LQ introduced from the #1 to #3 runner inlets 63b, 64b, 65b is greater than the amount of condensed water LQ introduced from the #4 runner inlet 66b, the amount of condensed water LQ introduced from the #3 runner inlet 65b is kept to about 7.6 times the amount of condensed water LQ introduced from the #4 runner inlet 66b, as shown by arrow D1. This shows that in the embodiment in which the ribs 62b to 62d are provided on the lower wall inner surface 62a of the surge tank 62, uneven distribution of the condensed water LQ within the surge tank 62 can be suppressed.

[0069] 5. Ribs 62b to 62d and pressure loss The effect on pressure loss of providing ribs 62b to 62d on the inner surface 62a of the lower wall of the surge tank 62 will be described with reference to Fig. 10. In Fig. 10, the comparative example and the embodiment are the same as those described with reference to Figs. 8(a) and (b), and the modified example is an example in which the deflection base portion 62i is not provided on the surge tank 62 in the embodiment shown in Fig. 8(a).

[0070] As shown in Fig. 10, if the pressure loss of the comparative example is taken as "100", then the example is about 93 and the modified example is about 94. From this, as explained using Fig. 8(b), it is considered that in the comparative example, since the surge tank 962 does not have ribs, the condensed water LQ accumulated in the surge tank 962 is pushed by fresh air and the like, causing imbalance, which results in a large pressure loss.

[0071] In contrast to this, in the example and modified examples, the movement of the condensed water LQ is restricted by providing the ribs 62b to 62d on the lower wall inner surface 62a of the surge tank 62, and it is believed that the pressure loss is kept lower than in the comparative example.

[0072] Furthermore, the pressure loss in the example is kept slightly lower than in the modified example. This is thought to be because, in the example, the deflection base 62i is provided at the bottom of the sidewall inner surface 62h of the surge tank 62, causing the fresh air and the like to pass over the tops 62j-62l of the ribs 62b-62d. That is, it can be seen that the example prevents the fresh air and the like from hitting the vicinity of the tops 62j-62l of the ribs 62b-62d and causing pressure loss.

[0073] 6.Effects In the intake device 3 of the engine 1 according to this embodiment, the ribs 62b to 62d are provided on the inner surface 62a of the lower wall of the surge tank 62 in the intake manifold 6, and therefore the movement of the condensed water LQ in the arrangement direction of the runner inlets 63b, 64b, 65b, and 66b (the above-mentioned predetermined direction) is restricted by the ribs 62b to 62d. As a result, the condensed water LQ accumulated on the inner surface 62a of the lower wall of the surge tank 62 is prevented from being concentrated downstream (on the side where the runner inlet 66b is provided) in the flow direction of air (a mixture of fresh air and EGR gas) in the surge tank 62, and misfires in the specific cylinders 2a (cylinders connected to the runners 66 and 65) caused by a large amount of condensed water LQ being introduced all at once can be prevented.

[0074] Furthermore, in the intake device 3 of the engine 1 according to this embodiment, a partition wall 61b is provided to separate the intake air introduction passage 61 from the space of the surge tank 62, so that the passage length of the intake air introduction passage 61 can be secured. However, due to the air flow within the surge tank 62, the condensed water LQ tends to be biased toward the downstream side of the air flow direction (the side where the runner inlet 66b is provided).

[0075] However, in the intake device 3 of the engine 1 according to this embodiment, the ribs 62b to 62d are provided on the inner surface 62a of the lower wall of the surge tank 62, so that it is possible to suppress uneven distribution of the condensed water LQ. Therefore, the intake device 3 is suitable for suppressing misfires in specific cylinders 2a caused by the condensed water LQ.

[0076] Furthermore, in the intake device 3 of the engine 1 according to this embodiment, the plurality of ribs 62b-62d are provided so as to extend from the portions (interval portions) 62e-62g between the runner inlets (openings) 63b, 64b, 65b, 66b of the plurality of runners 63-66, so that it is possible to limit the amount of condensed water LQ introduced into each of the plurality of runners 63-66 so as to reduce bias. Therefore, the intake device 3 is even more suitable for suppressing misfires in specific cylinders 2a caused by the condensed water LQ.

[0077] Furthermore, in the intake device 3 of the engine 1 according to this embodiment, the intake manifold 6 is formed by joining a plurality of components 6A to 6C, including a base component (first component) 6A and a center component (second component) 6B, so that it is possible to easily manufacture an intake manifold 6 with a complex internal structure having ribs 62b to 62d on the inner surface 62a of the lower wall of the surge tank 62.

[0078] Furthermore, in the intake device 3 of the engine 1 according to this embodiment, the runner inlets 63b, 64b, 65b, and 66b of the runners 63 to 66 are provided to be positioned higher than the inner surface 62a of the lower wall of the surge tank 62, which makes it possible to prevent the condensed water LQ from undesirably flowing from the surge tank 62 into the runners 63 to 66 when the engine 1 is stopped, for example. This makes it possible to prevent misfires from occurring in specific cylinders 2a when the engine 1 is restarted, for example.

[0079] Furthermore, in the intake device 3 of the engine 1 according to this embodiment, the runners 63 to 66 each have a portion that extends upward, so when the engine 1 is stopped, the condensed water LQ remaining in the runners 63 to 66 is returned to the surge tank 62. This is therefore even more suitable for preventing misfires from occurring in a specific cylinder 2a when the engine 1 is restarted, for example.

[0080] Furthermore, in the intake device 3 of the engine 1 according to this embodiment, the EGR passage 81 of the HP-EGR section 8 is connected to the intake manifold 6, so that an excessive rise in the combustion gas temperature can be suppressed, the generation of nitrogen oxides (NOx) can be suppressed, and pumping loss during intake can be reduced. Meanwhile, moisture contained in the EGR gas condenses and condensed water LQ generated from the EGR gas accumulates on the lower wall inner surface 62a of the surge tank 62, but by providing the ribs 62b to 62d on the lower wall inner surface 62a of the surge tank 62 as described above, the uneven distribution of the condensed water LQ can be suppressed, and misfires can be suppressed in specific cylinders 2a.

[0081] As described above, in the intake device 3 of the engine 1 according to this embodiment, by suppressing uneven distribution of the condensed water LQ in the surge tank 62, misfires in specific cylinders 2a caused by the condensed water LQ can be suppressed.

[0082] [Second embodiment] In the first embodiment, the engine 1 is provided with a four-cylinder engine body 2, but in this embodiment, an engine body with a six-cylinder engine body is used. The configuration of the intake manifold 106 provided in the intake device differs depending on the number of cylinders in the engine body, and this will be explained below. Except for the number of cylinders in the engine body and the configuration of the intake manifold 106, the intake device of the engine according to this embodiment has the same configuration as the intake device 3 of the engine 1 according to the first embodiment.

[0083] 1. External configuration of intake manifold 106 The external configuration of the intake manifold 106 will be described with reference to FIGS. 11 and 12. FIG.

[0084] As shown in Fig. 12, the intake manifold 106 included in the intake device according to this embodiment is also configured by joining a base member (first member) 106A, a center member (second member) 106B, and a cover member 106C. In this embodiment, the base member 106A, the center member 106B, and the cover member 106C are each formed from a resin material. Note that, in this embodiment, as in the first embodiment, the number of members constituting the intake manifold 106 and the shapes and materials of each member can be changed as appropriate.

[0085] 11 and 12, the intake air introduction passage 161 is formed of a cylindrical pipe and has an opening (inlet) 161a at one end to which a throttle valve is connected. The intake air introduction passage 161 is bent downward in an arc from the end where the inlet 161a is opened. As shown in FIG. 12, the intake air introduction passage 161 is connected to the space in a surge tank 162.

[0086] As shown in Fig. 12, in this embodiment as well, the surge tank 162 is disposed below the intake air introduction passage 161. As shown in Figs. 11 and 12, six runners (independent intake passages) 163-168 each extend upward from a portion communicating with the space in the surge tank 162 and are disposed so as to cover the upper part of the surge tank 162. As shown in Fig. 11, the intake air introduction passage 161 is disposed so as to extend vertically between the runners 165 and 166 in the arrangement direction of the runners 163-168. Note that although the runner outlets of the runners 163-168 are not shown in Figs. 11 and 12, they are disposed so as to open toward the right side of the paper in Fig. 12 (the opposite side to the orientation direction of the inlet 161a of the intake air introduction passage 161).

[0087] 2. Internal structure of surge tank 162 The internal structure of the surge tank 162 in the intake manifold 106 will be described with reference to FIG.

[0088] 13, the intake manifold 106 is configured by joining a cover member 106C and a base member 106A together with a center member 106B sandwiched therebetween, as indicated by arrows F1 and F2. The cover member 106C is provided with outer walls of the runners 164-168 and an inlet 161a of the intake passage 161.

[0089] The center member 106B is provided with a portion of the peripheral wall of the intake air introduction passage 161, a connection port 161b in the intake air introduction passage 161 that connects to the surge tank 162, and runner introduction ports 163b, 164b, 165b, 166b, 167b, and 168b in the runners 163-168 (connection ports in the runners 163-168 that connect to the surge tank 162). The connection port 161b in the intake air introduction passage 161 is formed so as to face the inner surface 162a of the lower wall of the surge tank 162. In other words, the intake air introduction passage 161 is formed so that the center line passing through the center of the connection port 161b intersects with the inner surface 162a of the lower wall of the surge tank 162.

[0090] The base member 106A is provided with a portion of the outer wall, including the lower wall, of the surge tank 162, and runner outlets (openings connected to intake ports in the engine body) 163a, 164a, 165a, 166a, 167a, and 168a of the runners 163 to 168. As shown in the enlarged portion of Figure 13, in the intake manifold 106, two ribs 162b and 162c are provided on the inner surface 162a of the lower wall of the surge tank 162, and a deflection base 162d is provided on the inner surface 162h of the side wall of the surge tank 162.

[0091] Of the two ribs 162b, 162c, rib 162b is formed to extend from a portion between runner inlet 164b and runner inlet 165b toward the inner surface of the side wall (side wall inner surface 162h) opposite the inner surface of the side wall on which runner inlets 163b, 164b, 165b, 166b, 167b, and 168b are provided. Similarly, rib 162c is formed to extend from a portion between runner inlet 166b and runner inlet 167b toward side wall inner surface 162h.

[0092] The deflection table portion 162d is formed in the region between the rib 162b and the rib 162c in the predetermined direction. The deflection table portion 162d is provided on the inner surface 162h of the side wall of the surge tank 162 so that the edge on the side where the runner inlets 163b, 164b, 165b, 166b, 167b, and 168b are provided is higher than the tops of the ribs 162b and 162c. The deflection table portion 162d is formed such that there is a space in at least a portion of the region between the ribs 162b and 162c in the predetermined direction.

[0093] 3. Suppression of uneven air flow and condensed water distribution within the surge tank 162 13, in the intake manifold 106, air (a mixture of fresh air and EGR gas) introduced into the surge tank 162 through the intake air introduction passage 161 collides with the upper surface of a deflection base 162d formed on the inner surface 162h of the side wall of the surge tank 162. Part of the air that collides with the upper surface of the deflection base 162d is sent from runner inlets 165b and 166b toward the runners 165 and 166 (arrow F3), another part is sent from runner inlets 167b and 168b toward the runners 167 and 168 (arrow F4), and the remaining part is sent from runner inlets 163b and 164b to the runners 163 and 164 (arrow F5).

[0094] Here, even in the intake device of the engine according to this embodiment, condensed water accumulates on the inner surface 162a of the lower wall of the surge tank 162. In this case, too, by providing the ribs 162b, 162c on the inner surface 162a of the lower wall of the surge tank 162, the movement of condensed water from the region between the ribs 162b, 162c to the regions 162f, 162g on both sides of the ribs 162b, 162c in the above-mentioned predetermined direction due to the influence of the air flow is restricted.

[0095] Furthermore, in the intake manifold 106, a deflection base 162d is provided on the inner surface 162h of the side wall of the surge tank 162, which prevents the air introduced into the surge tank 162 through the intake air introduction passage 161 from directly hitting the condensed water accumulated in the area 162e. This is therefore suitable for preventing misfires in a specific cylinder caused by a large amount of condensed water being introduced into that specific cylinder all at once.

[0096] In the intake device of the engine according to this embodiment, two ribs 162b, 162c are provided on the inner surface 162a of the lower wall of the surge tank 162, so that the movement of condensed water is restricted by the ribs 162b, 162c, thereby achieving the same effect as in the first embodiment.

[0097] [Variations] In the intake device 3 of the engine 1 according to the first embodiment, a partition 61b is provided in the intake manifold 6 to separate a portion between the intake introduction passage 61 and the surge tank 62, but in the present invention, it is not necessarily required to provide a partition.

[0098] Furthermore, in the intake device 3 of the engine 1 according to the first embodiment, three ribs 62b to 62d are provided on the inner surface 62a of the lower wall of the surge tank 62 in the intake manifold 6, but in the present invention, it is sufficient to provide at least one rib.

[0099] Furthermore, in the intake device of the engine according to the second embodiment, two ribs 162b, 162c are provided on the inner surface 162a of the lower wall of the surge tank 162 in the intake manifold 106, but in the present invention, three or more ribs may be provided.

[0100] Furthermore, in the first and second embodiments, the runner inlets 63b, 64b, 65b, 66b, 163b, 164b, 165b, 166b, 167b, 168b of the runners 63-66, 163-168 in the intake manifold 6, 106 are arranged at a position higher than the inner surface 62a, 162a of the lower wall of the surge tank 62, 162, but in the present invention, the runner inlets may be arranged at the same height level as the inner surface of the lower wall of the surge tank or at a position lower than the inner surface of the lower wall of the surge tank.

[0101] Furthermore, in the first and second embodiments, EGR gas is recirculated to the intake manifold 6, 106 together with fresh air, but in the present invention, recirculation of EGR gas to the intake manifold is not essential.

[0102] Furthermore, in the first and second embodiments, the intake manifold 6, 106 is formed by combining three members 6A, 6B, 6C, 106A, 106B, and 106, but in the present invention, the intake manifold may be formed by combining two members, or may be formed by combining four or more members.

[0103] Furthermore, in the first and second embodiments, an engine equipped with a turbocharger is used as an example, but a turbocharger is not an essential component in the present invention.

[0104] In addition, in the first embodiment described above, the ribs 62b to 62d provided on the lower wall inner surface 62a of the surge tank 62 in the intake manifold 6 have respective apexes 62j to 62l shaped to follow the lower wall inner surface 62a of the surge tank 62, but in the present invention, the apexes may have a straight line shape or a shape that combines multiple straight lines and curves.

[0105] Furthermore, in the first embodiment, a four-cylinder engine was used as an example of the engine body 2, and in the second embodiment, a six-cylinder engine was used as the engine body, but the present invention may also use an engine body with three cylinders or five or more cylinders.

[0106] Furthermore, in the first and second embodiments, the surge tanks 62, 162 in the intake manifolds 6, 106 are provided with deflection bases 62i, 162d, but in the present invention, it is not essential to provide the surge tanks with deflection bases. [Explanation of symbols]

[0107] 1 engine 3. Intake system 6,106 Intake manifold 6A, 106A Base member (first member) 6B, 106B Center member (second member) 6C, 106C Cover member 61,161 Intake passage 61b Bulkhead 62,162 surge tank 62a, 162a Lower wall inner surface 62b, 62c, 62d, 162b, 162c Ribs 63~66, 163~168 Runner (Independent Intake Passage)

Claims

1. An intake system for an engine, comprising: an engine body having a plurality of cylinders and a cylinder head in which intake ports connected to each of the plurality of cylinders are formed; an intake manifold through which air passes to the plurality of intake ports in the engine body; Equipped with The intake manifold is a plurality of independent intake passages arranged along a cylinder row direction in the engine body and connected to the plurality of intake ports, respectively; a surge tank having a space where the plurality of independent intake passages are gathered, and arranged so that openings of the plurality of independent intake passages are aligned in a predetermined direction; an intake air introduction passage for introducing air into the surge tank; and the surge tank has a rib provided on an inner surface of a lower wall of the surge tank, the rib extending from a portion between at least two adjacent openings among the plurality of openings toward the inner surface of the side wall that faces the side wall in which the plurality of openings are provided, with the space therebetween; the plurality of openings are provided so that their lower end portions are positioned above the inner surface of the lower wall of the surge tank, Each of the plurality of independent intake passages has a portion extending upward from the opening, the rib is connected to each of the inner surface of the bottom wall, the inner surface of the side wall in which the plurality of openings are provided, and the inner surface of the opposing side wall; Engine intake system.

2. 2. The engine intake system according to claim 1, the intake air introduction passage is formed to extend from one end side to the other end side of the surge tank along the predetermined direction, and is in communication with the space in the surge tank at the other end side, The intake air introduction passage and the space in the surge tank are separated by a partition wall except for a communicating portion on the other end side. Engine intake system.

3. The engine intake system according to claim 1 or 2, A plurality of the ribs are provided so as to extend from between adjacent ones of the openings. Engine intake system.

4. 2. The engine intake system according to claim 1, the intake air introduction passage is connected to the space of the surge tank at a central portion in the predetermined direction so as to be oriented toward the inner surface of the lower wall at a portion communicating with the space of the surge tank, The ribs are provided in two rows on both sides of the communication portion where the intake air introduction passage communicates with the space in the predetermined direction. Engine intake system.

5. The engine intake device according to any one of claims 1 to 4, The intake manifold is configured by joining a plurality of members including a first member and a second member that are joined together in the direction in which the ribs extend to define the space of the surge tank. Engine intake system.

6. The engine intake device according to any one of claims 1 to 5, An EGR passage for introducing EGR gas is connected to the intake manifold. Engine intake system.

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