JP7435286B2 - Internal combustion engine intake pipe - Google Patents

Description

The present invention relates to an intake pipe for an internal combustion engine.

As shown in Patent Document 1, an intake pipe of an internal combustion engine is formed with an intake passage through which intake air from the engine passes. A gas introduction port for introducing a gas other than intake air into the intake passage is provided on the inner wall surface of the intake pipe. Note that examples of the gas introduced into the intake passage from the gas inlet include EGR gas and blow-by gas.

JP2018-84158A

In the intake pipe, when the gas is introduced into the intake passage from the gas introduction port, the cross-sectional area of the gas flow rapidly increases at the boundary between the gas introduction port and the intake passage. In such a portion where the flow end cross-sectional area rapidly increases, the gas flow does not follow the inner wall surface of the intake passage, but separates from the inner wall surface toward the center of the intake passage. When the gas flow separates from the inner wall surface of the intake passage, a vortex is generated near the inner wall, and as the vortex is generated, pressure loss increases when the intake air passes through the intake passage.

An object of the present invention is to provide an intake pipe for an internal combustion engine that can suppress pressure loss from increasing when intake air passes through an intake passage due to the introduction of a gas different from the intake air into the intake passage. It is about providing.

Below, means for solving the above problems and their effects will be described.
The intake pipe of an internal combustion engine that solves the above problem has an intake passage through which the engine's intake air passes, and the inner wall of the intake passage has a gas inlet that introduces a gas different from the intake air into the intake passage. It has a mouth. A rib extending from the gas inlet toward the downstream side of the flow of the intake air is formed on a portion of the inner wall surface of the intake passage adjacent to the gas inlet on the downstream side in the flow direction of the intake air. There is.

When gas is introduced into the intake passage from the gas inlet, the flow cross-sectional area of the gas increases rapidly, and the flow of the gas in the rapidly increasing area does not flow along the inner wall of the intake passage, but flows from the inner wall of the intake passage. Try to peel it off toward the center. However, according to the above configuration, among the gas introduced into the intake passage from the gas inlet, the gas flowing near the inner wall surface of the intake passage flows along the rib. As a result, the flow of the gas near the inner wall surface of the intake passage can be suppressed from separating from the inner wall surface toward the center of the intake passage, and the generation of vortices near the inner wall surface due to the separation is suppressed. . Therefore, it is possible to suppress an increase in pressure loss when the intake air passes through the intake passage due to the vortex flow generated near the inner wall surface of the intake passage.

1 is a schematic diagram showing an intake manifold and an internal combustion engine. FIG. 2 is a plan view showing an intake manifold and an internal combustion engine. FIG. 3 is an enlarged cross-sectional view showing the vicinity of the gas inlet in the intake manifold. FIG. 4 is a plan view showing the rib as viewed from the direction of arrow A in FIG. 3; A schematic diagram showing the flow of gas introduced into the intake passage from the gas inlet. A schematic diagram showing the flow of gas introduced into the intake passage from the gas inlet.

An embodiment of an intake pipe for an internal combustion engine will be described below with reference to FIGS. 1 to 6.
As shown in FIGS. 1 and 2, an intake manifold 2 is provided in an intake system of an internal combustion engine 1. As shown in FIGS. The intake manifold 2 plays the role of an intake pipe in which an intake passage is formed through which intake air from the internal combustion engine 1 flows.

The intake manifold 2 includes a surge tank 4 having an intake port 3. Intake air (atmosphere) taken into the intake system of the internal combustion engine 1 from the air cleaner flows into the surge tank 4 via the intake port 3 . Furthermore, the intake manifold 2 includes a plurality of branch portions 5 extending from the surge tank 4 toward each cylinder of the internal combustion engine 1. An intake passage 6 through which intake air from the internal combustion engine 1 passes is formed inside the surge tank 4 and each branch portion 5 . The intake passage 6 branches into a plurality of sections from inside the surge tank 4 to inside each branch portion 5 and is connected to each cylinder of the internal combustion engine 1 .

Each branch portion 5 of the intake manifold 2 is integrally formed with a connecting pipe 7 for introducing a gas different from the intake air of the internal combustion engine 1 into the intake passage 6. Note that such gases include EGR gas and blow-by gas (EGR gas in this example). The EGR gas introduced into the intake passage 6 from the connecting pipe 7 is mixed with intake air passing through the intake passage 6, and is supplied to each cylinder of the internal combustion engine 1 together with the intake air. Note that the intake air and EGR gas supplied to each cylinder of the internal combustion engine 1 are preferably mixed evenly in order to achieve good fuel combustion in those cylinders.

FIG. 3 shows an enlarged view of the connecting pipe 7 at the branch portion 5 of the intake manifold 2 and its surroundings. As can be seen from FIG. 3, the portion of the connecting pipe 7 located inside the branch portion 5 becomes a protruding portion 7a that protrudes from the inner wall surface 8 of the branch portion 5 (intake passage 6) toward the center of the intake passage 6. ing. The open end of the connecting pipe 7 in the intake passage 6 serves as a gas introduction port 9 for introducing EGR gas from the connecting pipe 7 into the intake passage 6. This gas introduction port 9 is formed in a protrusion 7a of the connecting pipe 7, and is provided on the inner wall surface 8 of the intake passage 6 by the protrusion 7a.

Among the parts of the inner wall surface 8 of the intake passage 6 adjacent to the gas inlet 9 (projection 7a), on the downstream side in the flow direction of the intake air, there is a wall located downstream from the gas inlet 9 in the flow direction of the intake air. A rib 10 is formed that extends toward the substrate. The rib 10 protrudes from the inner wall surface 8 and is formed to connect the protrusion 7 a and the inner wall surface 8 . Further, the height of the rib 10 protruding from the inner wall surface 8 of the intake passage 6 is configured to gradually decrease toward the downstream side in the flow direction of the intake air. FIG. 4 shows the rib 10 viewed from the direction of arrow A in FIG. As can be seen from FIG. 4, the thickness of the rib 10 in the direction perpendicular to the direction of protrusion from the inner wall surface 8 (vertical direction in FIG. 4) gradually becomes thinner toward the downstream side in the flow direction of the intake air. ing.

Next, the function of the intake pipe (intake manifold 2) of the internal combustion engine in this embodiment will be explained.
In the intake manifold 2, when EGR gas is introduced into the intake passage 6 from the gas introduction port 9, part of the EGR gas flows toward the center of the intake passage 6, and the rest of the EGR gas flows into the intake passage 6. It tries to flow near the inner wall surface 8. Of the inner wall surface 8 of the intake passage 6 in the intake manifold 2, which is adjacent to the gas inlet 9 (protrusion 7a), a portion on the downstream side in the flow direction of intake air in the intake passage 6 is provided with gas. A rib 10 (FIG. 3) is formed that extends from the inlet 9 toward the downstream side of the flow of the intake air.

If such ribs 10 were not formed, when EGR gas is introduced from the gas inlet 9 into the intake passage 6, the cross-sectional area of the passage through which the EGR gas flows would rapidly increase, so that The flow of EGR gas near the inner wall surface 8 tends to separate toward the center of the intake passage 6 instead of along the inner wall surface 8. When the flow of EGR gas near the inner wall surface 8 separates from the inner wall surface 8 side toward the center of the intake passage 6, a vortex is generated near the inner wall surface 8 as shown by arrow B in FIG. The pressure loss when the intake air passes through the intake passage 6 increases.

However, since the intake manifold 2 is provided with the above-mentioned rib 10, the flow of EGR gas near the inner wall surface 8 of the intake passage 6 among the EGR gas introduced into the intake passage 6 from the gas introduction port 9 is reduced. It follows the rib 10 as shown by arrow C in FIG. As a result, the flow of the EGR gas near the inner wall surface 8 of the intake passage 6 can be suppressed from separating from the inner wall surface 8 toward the center of the intake passage 6, and as a result of the separation, the flow of the EGR gas near the inner wall surface 8 can be prevented from separating from the inner wall surface 8 near the inner wall surface 8 as shown in FIG. The generation of vortices as shown by arrow B is suppressed. Therefore, it is possible to suppress an increase in pressure loss when the intake air passes through the intake passage 6 due to the vortex flow generated near the inner wall surface 8 of the intake passage 6.

According to this embodiment described in detail above, the following effects can be obtained.
(1) As a gas different from the intake air of the internal combustion engine (EGR gas) is introduced into the intake passage 6, pressure loss when the intake air passes through the intake passage 6 can be suppressed from increasing.

(2) As shown in FIG. 3, the rib 10 protrudes from the inner wall surface 8 of the intake passage 6, and the height of its protrusion from the inner wall surface 8 is the downstream side in the flow direction of intake air within the intake passage 6. It is lowered towards the side. In this way, by gradually decreasing the protruding height of the rib 10 with respect to the inner wall surface 8 toward the downstream side in the flow direction of the intake air, it is possible to suppress the occurrence of a step with the inner wall surface 8 at the downstream end of the rib 10. , it is possible to suppress the generation of vortex flow of intake air at the step.

(3) The thickness of the rib 10 in the direction perpendicular to its protruding direction (vertical direction in FIG. 4) is made thinner toward the downstream side in the flow direction of intake air in the intake passage 6. Therefore, among the gas introduced into the intake passage 6 from the gas inlet 9, the gas that has flowed downstream in the intake passage 6 along both side surfaces of the rib 10 in the thickness direction is transferred to the downstream end of the rib 10. When flowing further downstream from the above, vortices are less likely to occur near the downstream ends of the ribs 10, and the stream flows smoothly downstream.

(4) The inner wall surface 8 of the intake passage 6 in the intake manifold 2 is formed with a protrusion 7a that protrudes toward the center of the intake passage 6. A gas introduction port 9 for introducing EGR gas into the intake passage 6 is formed in the protrusion 7a. In this case, most of the EGR gas introduced into the intake passage 6 from the gas introduction port 9 formed in the protrusion 7a merges with the intake air at the center of the intake passage 6 where the flow of intake air is fast. can be mixed efficiently. However, since the protrusion 7a having the gas inlet 9 protrudes from the inner wall surface 8 of the intake passage 6, there is a risk that vortices may easily occur downstream of the protrusion 7a in the intake passage 6. However, the generation of such a vortex can be suppressed by the rib 10 formed to connect the protrusion 7a and the inner wall surface 8.

(5) The intake passage 6 of the intake manifold 2 is branched into a plurality of parts and connected to each cylinder of the internal combustion engine 1, and the gas introduction port 9 and the rib 10 are provided at each branched part of the intake passage 6. In the branched portion of the intake passage 6, the flow cross-sectional area of the intake air becomes smaller and the flow rate of the intake air becomes faster. Therefore, in the branched portion of the intake passage 6, the difference in flow velocity of intake air between the vicinity of the inner wall surface 8 and the central portion tends to become large, and of the EGR gas introduced from the gas inlet 9, the gas near the inner wall surface 8 However, the generation of such a vortex can be suppressed by the ribs 10.

Note that the above embodiment can also be modified as follows, for example. The above embodiment and the following modification examples can be implemented in combination with each other within a technically consistent range.
- The gas introduced into the intake passage 6 from the gas inlet 9 may be a gas other than EGR gas (such as blow-by gas).

- The gas inlet 9 and the rib 10 do not necessarily need to be provided at a branched part of the intake passage 6, but may be provided at a part other than that part (a non-branched part), for example, in a part corresponding to the surge tank 4. It may be.

- It is not necessary to apply the present invention to the intake manifold 2, and the present invention may be applied to an intake pipe upstream of the intake manifold 2 in the intake system of the internal combustion engine 1.

- The gas inlet 9 does not necessarily need to be formed in the protrusion 7a, and may be formed to open at the inner wall surface 8 of the intake passage 6, for example.
- The thickness of the rib 10 in the direction orthogonal to the protruding direction does not necessarily need to be made thinner toward the downstream side in the flow direction of the intake air in the intake passage 6.

- The height of the protrusion of the rib 10 from the inner wall surface 8 of the intake passage 6 does not necessarily need to be lowered toward the downstream side in the flow direction of intake air within the intake passage 6.

1...Internal combustion engine 2...Intake manifold 3...Intake port 4...Surge tank 5...Branch portion 6...Intake passage 7...Connection pipe 7a...Protrusion part 8...Inner wall surface 9...Gas inlet 10...Rib

Claims (5)

An intake pipe for an internal combustion engine, which has an intake passage through which the intake air of the internal combustion engine passes, and a gas inlet port for introducing a gas other than the intake air into the intake passage is provided on the inner wall surface of the intake passage. In,
Of the inner wall surface of the intake passage adjacent to the gas inlet, a portion on the downstream side in the flow direction of the intake air is provided with the intake air from the downstream end of the gas inlet in the flow direction of the intake air. An intake pipe for an internal combustion engine, characterized in that a rib is formed that extends toward the downstream side of the flow. The internal combustion engine according to claim 1, wherein the rib protrudes from an inner wall surface of the intake passage, and the height of the rib protrudes from the inner wall surface decreases toward the downstream side in the flow direction of the intake air. intake pipe. 3. The intake pipe for an internal combustion engine according to claim 1, wherein the thickness of the rib in a direction perpendicular to its protruding direction becomes thinner toward the downstream side in the flow direction of the intake air. A protrusion that protrudes toward the center of the intake passage is formed on the inner wall surface of the intake passage, the gas inlet is formed in the protrusion, and the rib is connected to the protrusion and the intake passage. The intake pipe for an internal combustion engine according to any one of claims 1 to 3, wherein the intake pipe is formed so as to connect with an inner wall surface of the intake pipe. The intake passage according to any one of claims 1 to 4, wherein the intake passage is branched into a plurality of parts and connected to each cylinder of the internal combustion engine, and the gas introduction port and the rib are each provided at a branched part of the intake passage. The intake pipe of the internal combustion engine described in .