supercharger

Abstract

A supercharger includes a turbine wheel, a turbine housing, and a connection pipe. The connection pipe includes a partition wall that separates an inside of the connection pipe into a first passage and a second passage. When a cross section orthogonal to a rotation axis of the turbine wheel is observed, a line segment that extends from a top end of the partition wall toward an upstream in a flow direction of exhaust gas and that defines a boundary of the first passage and the partition wall is a first downstream side line segment. A line segment that extends from the top end of the partition wall toward the upstream in the flow direction of the exhaust gas and that defines a boundary of the second passage and the partition wall is a second downstream side line segment. The first downstream side line segment is parallel to the second downstream side line segment.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a supercharger. BACKGROUND

[0002] In Japanese Patent Application Publication No. 2021-134719, a turbine housing of a supercharger is disclosed. The turbine housing has a turbine scroll chamber. The turbine scroll chamber communicates with an exhaust gas introduction passage. SUMMARY

[0003] PROBLEMS TO BE SOLVED BY THE INVENTION

[0004] In the turbine housing, it is required that exhaust gas flows smoothly from the exhaust gas introduction passage into the turbine scroll chamber.

[0005] MEANS FOR SOLVING THE PROBLEMS

[0006] A supercharger according to an aspect of the present disclosure is a supercharger of an internal combustion engine that has a first cylinder and a second cylinder different from the first cylinder in a period of a piston stroke. The supercharger has a turbine impeller, a turbine housing that houses the turbine impeller, and a connection pipe that connects the turbine housing and the internal combustion engine. The connection pipe has a contact surface that contacts the internal combustion engine, a first passage that communicates with a first exhaust port of the first cylinder, a second passage that communicates with a second exhaust port of the second cylinder, and a partition wall that extends from the contact surface to divide an inside of the connection pipe into the first passage and the second passage. The turbine housing has a scroll passage that extends along a circumferential direction of the turbine impeller between an inner wall of the turbine housing and an outer circumferential surface of the turbine impeller. The scroll passage communicates with the first passage and the second passage so that exhaust gas that has passed through the first passage and exhaust gas that has passed through the second passage are merged. A cross section of the scroll passage that is orthogonal to an axis of rotation of the turbine impeller and in which a cross-sectional area is largest is a prescribed cross section. When the prescribed cross section is viewed, a line segment that extends from a top end of the partition wall toward an upstream of a flow direction of exhaust gas in the first passage and that defines a boundary of the first passage and the partition wall is a first downstream side line segment, and a line segment that extends from the top end toward an upstream of a flow direction of exhaust gas in the second passage and that defines a boundary of the second passage and the partition wall is a second downstream side line segment. The first downstream side line segment is parallel to the second downstream side line segment. BRIEF DESCRIPTION OF DRAWINGS

[0007] Figure 1 is a schematic view that shows an intake and exhaust system of an internal combustion engine that includes a supercharger according to an embodiment.

[0008] Figure 2 isFigure 1 Side view of the turbocharger.

[0009] Figure 3 It is along Figure 2 A sectional view along line 3-3.

[0010] Figure 4 It is Figure 3 An enlarged cross-sectional view of the area near the connecting pipe of the supercharger.

[0011] Figure 5 It is along Figure 4 A sectional view along line 5-5.

[0012] Figure 6 This is an enlarged cross-sectional view of the vicinity of the connecting pipe when the first downstream segment and the second downstream segment of the turbocharger are not parallel. Detailed Implementation

[0013] Hereinafter, one embodiment of the booster 10 will be described.

[0014] <Internal Combustion Engine 30>

[0015] like Figure 1 As shown, the internal combustion engine 30 has an intake manifold 33, four cylinders C1, C2, C3, C4, a first exhaust port 31, and a second exhaust port 32.

[0016] The intake manifold 33 has four branch flow paths on its downstream side, each of which is connected to cylinders C1 to C4. A throttle valve 34 is located upstream of the four branch flow paths in the intake manifold 33.

[0017] Cylinders C1, C2, C3, and C4 are arranged in this order. For each cylinder C1 to C4, the intake stroke, compression stroke, combustion stroke, and exhaust stroke occur in this order. When cylinder C1 is in the intake stroke, cylinders C2, C3, and C4 are in the compression stroke, exhaust stroke, and combustion stroke, respectively. When cylinder C1 is in the compression stroke, cylinders C2, C3, and C4 are in the combustion stroke, intake stroke, and exhaust stroke, respectively. When cylinder C1 is in the combustion stroke, cylinders C2, C3, and C4 are in the exhaust stroke, compression stroke, and intake stroke, respectively. When cylinder C1 is in the exhaust stroke, cylinders C2, C3, and C4 are in the intake stroke, combustion stroke, and compression stroke, respectively.

[0018] The cylinder C1 and the cylinder C4 are first cylinders that communicate with the first exhaust port 31. The cylinder C2 and the cylinder C3 are second cylinders that communicate with the second exhaust port 32. As described above, the combustion strokes of the first cylinders and the second cylinders are different in timing. The cylinder C1 and the cylinder C4 are sometimes referred to as an N1 cylinder and an N3 cylinder, respectively. The cylinder C2 and the cylinder C3 are sometimes referred to as an N4 cylinder and an N2 cylinder, respectively. The combustion strokes come in the order of the cylinder C1, the cylinder C3, the cylinder C4, and the cylinder C2. That is, the combustion strokes come in the order of the N1 cylinder, the N2 cylinder, the N3 cylinder, and the N4 cylinder.

[0019] <Air intake and exhaust system of internal combustion engine 30>

[0020] Reference Figure 1 and Figure 2 An outline of the air intake and exhaust system of the internal combustion engine 30 will be described.

[0021] As shown in Figure 1 , the air intake and exhaust system of the internal combustion engine 30 is provided with an air cleaner 40, a first intake passage 41, a supercharger 10, a second intake passage 42, an intercooler 43, an exhaust passage 45, and a three-way catalyst 46.

[0022] The air cleaner 40 is connected to the supercharger 10 through the first intake passage 41. The supercharger 10 is connected to the intercooler 43 through the second intake passage 42. The intercooler 43 is connected to the intake manifold 33 of the internal combustion engine 30. The first exhaust port 31 and the second exhaust port 32 are connected to the supercharger 10.

[0023] As shown in Figure 1 and Figure 2 , the supercharger 10 is connected to the exhaust passage 45. The three-way catalyst 46 is connected downstream of the exhaust passage 45.

[0024] Intake air flows into the compressor housing 12 of the supercharger 10 through the air cleaner 40 and the first intake passage 41. The intake air is compressed by the compressor impeller 11 provided in the compressor housing 12. The compressed intake air flows into the intake manifold 33 through the second intake passage 42 and the intercooler 43.

[0025] Exhaust gas discharged from the internal combustion engine 30 flows into the turbine housing 15 of the supercharger 10 through the first exhaust port 31 or the second exhaust port 32. The exhaust gas flowing into the turbine housing 15 rotates the turbine impeller 14 provided in the turbine housing 15. The exhaust gas flowing into the turbine housing 15 is discharged to the outside through the exhaust passage 45 and the three-way catalyst 46.

[0026] <Supercharger 10>

[0027] As shown in Figure 1 and Figure 2As shown in the figure, the supercharger 10 is provided with a compressor impeller 11, a compressor housing 12, a connecting shaft 13, a turbine impeller 14, a turbine housing 15, and a connection pipe 20.

[0028] The compressor housing 12 houses the compressor impeller 11. The first intake passage 41 and the second intake passage 42 are connected to the compressor housing 12.

[0029] As shown in the figure, Figure 3 The connection pipe 20 has a first passage 21, a second passage 22, a partition wall 23, and a contact surface 24. The connection pipe 20 connects the turbine housing 15 and the internal combustion engine 30. The connection pipe 20 contacts the internal combustion engine 30 via the contact surface 24. The connection pipe 20 is bent between the turbine housing 15 and the internal combustion engine 30. The connection pipe 20 extends in a direction perpendicular to the contact surface 24 in the vicinity of the contact surface 24. The partition wall 23 divides the inside of the connection pipe 20 into the first passage 21 and the second passage 22. The first passage 21 and the second passage 22 communicate with the first exhaust port 31 and the second exhaust port 32, respectively. Figure 3 A cross section of the scroll passage 18 orthogonal to the rotational axis of the turbine impeller 14, that is, a prescribed cross section, is shown.

[0030] As shown in the figure, Figure 3 and Figure 4 If the flow direction of the first exhaust flow E1 in the first passage 21 and the flow direction of the second exhaust flow E2 in the second passage 22 are set as the flow direction of the exhaust gas in the connection pipe 20, the partition wall 23 extends from the contact surface 24 toward the flow direction of the exhaust gas in the connection pipe 20.

[0031] In this specification, the first downstream-side line segment 21b and the second downstream-side line segment 22b are defined as follows. That is, as shown in the figure, Figure 4 The first downstream-side line segment 21b is a line segment that extends from the top end 26 of the partition wall 23 toward the upstream in the flow direction of the first exhaust flow E1 and that defines the boundary of the first passage 21 and the partition wall 23. The second downstream-side line segment 22b is a line segment that extends from the top end 26 of the partition wall 23 toward the upstream in the flow direction of the second exhaust flow E2 and that defines the boundary of the second passage 22 and the partition wall 23. The first downstream-side line segment 21b and the second downstream-side line segment 22b are parallel to each other.

[0032] As shown in the figure, Figure 4 and Figure 5 A face of the partition wall 23 that includes the first downstream-side line segment 21b is set as a first face 21a. A face of the partition wall 23 that includes the second downstream-side line segment 22b is set as a second face 22a. The first face 21a and the second face 22a face each other with the partition wall 23 interposed therebetween. The first face 21a and the second face 22a are each a plane and are parallel to each other.

[0033] The portion of the partition wall 23 sandwiched by the first face 21a and the second face 22a is set as a downstream portion 25. The flow path cross-sectional areas of the portions of the first passage 21 and the second passage 22 that sandwich the downstream portion 25 are equal to each other.

[0034] As shown in Figure 4 The partition wall 23 has a first upstream-side line segment 21c and a second upstream-side line segment 22c. The first upstream-side line segment 21c is connected to the first downstream-side line segment 21b and extends toward the contact face 24 in the connection pipe 20. The second upstream-side line segment 22c is connected to the second downstream-side line segment 22b and extends toward the contact face 24. The first upstream-side line segment 21c is inclined with respect to the second upstream-side line segment 22c in such a manner that the distance between the first upstream-side line segment 21c and the second upstream-side line segment 22c becomes wider as the contact face 24 is approached.

[0035] As shown in Figure 3 The turbine housing 15 is substantially circular in cross section. The turbine housing 15 houses a turbine impeller 14 that is substantially circular in cross section. The turbine impeller 14 has a rotation center 19. An imaginary line that passes through the rotation center 19 and extends in a direction orthogonal to the cross section shown in Figure 3 The imaginary line is a rotation axis.

[0036] As shown in Figure 1 The compressor impeller 11 and the turbine impeller 14 are connected by a connecting shaft 13.

[0037] As shown in Figure 3 The turbine housing 15 has a scroll passage 18 that extends along the circumference of the turbine impeller 14 between the inner wall 16 of the turbine housing 15 and the outer peripheral surface 17 of the turbine impeller 14. The scroll passage 18 is a passage that communicates with the first passage 21 and the second passage 22 of the connection pipe 20 and is a passage in which the first exhaust flow E1 and the second exhaust flow E2 are merged.

[0038] As shown in Figure 1 and Figure 2 A bypass passage 44 is provided in the turbine housing 15. The bypass passage 44 extends from the turbine housing 15 toward an exhaust passage 45. An exhaust gas bypass valve 44a is provided in the bypass passage 44. Exhaust gas flows through the bypass passage 44 to bypass the turbine impeller 14.

[0039] The operation of the present embodiment will be described.

[0040] Because exhaust gas is intermittently discharged from the internal combustion engine 30 to the first exhaust port 31 and the second exhaust port 32, the pressure in the first exhaust port 31 and the second exhaust port 32 changes periodically, resulting in pressure pulsations. Furthermore, because the timing of exhaust gas discharge from the internal combustion engine 30 to the first exhaust port 31 and the second exhaust port 32 is different, the pressure in the first exhaust port 31 and the second exhaust port 32 at the same time will differ. Therefore, if the pressure in the first exhaust port 31 is higher than the pressure in the second exhaust port 32, exhaust gas discharged from the first exhaust port 31 to the connecting pipe 20 may flow back to the second exhaust port 32. Conversely, if the pressure in the second exhaust port 32 is higher than the pressure in the first exhaust port 31, exhaust gas discharged from the second exhaust port 32 to the connecting pipe 20 may flow back to the first exhaust port 31.

[0041] According to the above configuration, the connecting pipe 20 has a partition wall 23 that divides the interior of the connecting pipe 20 into a first passage 21 communicating with the first exhaust port 31 and a second passage 22 communicating with the second exhaust port 32. Therefore, it is difficult for exhaust to flow back from the first exhaust port 31 to the second exhaust port 32 or from the second exhaust port 32 to the first exhaust port 31.

[0042] like Figure 6 As shown, when the first downstream segment 21b and the second downstream segment 22b of the partition wall 23 are not parallel, the following problem may occur: When the first exhaust flow E1 and the second exhaust flow E2 converge in the vortex passage 18, their flow directions are different. Therefore, the first exhaust flow E1 and the second exhaust flow E2 may interfere with each other, reducing the exhaust velocity within the vortex passage 18. Consequently, the first exhaust flow E1 and the second exhaust flow E2 are prone to backflow into the lower pressure passages in the first passage 21 and the second passage 22. Therefore, the effect of suppressing the aforementioned exhaust backflow is diminished.

[0043] Based on the above configuration, the first exhaust flow E1 and the second exhaust flow E2 easily become parallel, and the first exhaust flow E1 and the second exhaust flow E2 are unlikely to interfere with each other. Furthermore, based on the above configuration, the first exhaust flow E1 and the second exhaust flow E2 flow in a state of close proximity. Therefore, when the velocity of the first exhaust flow E1 is higher than the velocity of the second exhaust flow E2, the second exhaust flow E2 is attracted to the first exhaust flow E1. When the velocity of the second exhaust flow E2 is higher than the velocity of the first exhaust flow E1, the first exhaust flow E1 is attracted to the second exhaust flow E2. Therefore, the aforementioned exhaust backflow can be further suppressed. In this specification, the phenomenon that the lower-velocity airflow in the first exhaust flow E1 and the second exhaust flow E2 is attracted to the higher-velocity airflow is called the "Venturi effect".

[0044] The effects of this implementation method will be explained.

[0045] (1) The first downstream-side line section 21b is parallel to the second downstream-side line section 22b.

[0046] According to such a configuration, the above-mentioned effects are exerted, so the above-mentioned exhaust gas backflow can be suppressed.

[0047] (2) The internal combustion engine 30 has a combustion order of the cylinders Cl, C3, C4, and C2, and the cylinders Cl, C2, C3, and C4. The first cylinder includes the cylinders Cl and C4. The second cylinder includes the cylinders C2 and C3.

[0048] In a configuration different from the above-mentioned configuration, for example, in which the first cylinder is the cylinders Cl and C3, and the second cylinder is the cylinders C4 and C2, the following problem can occur. That is, during a certain period, exhaust gas is continuously introduced from the cylinders Cl and C3 to the first exhaust port 31, so the pressure of the first exhaust flow El becomes higher than that of the second exhaust flow E2, and the difference between the pressures of the two exhaust flows El, E2 also becomes large. Similarly, during another period, exhaust gas is continuously introduced from the cylinders C4 and C2 to the second exhaust port 32, so the pressure of the second exhaust flow E2 becomes higher than that of the first exhaust flow El, and the difference between the pressures of the two exhaust flows El, E2 also becomes large. Thus, the above-mentioned exhaust gas backflow is likely to occur.

[0049] In this regard, according to the above-mentioned configuration, exhaust gas alternately flows into the first passage 21 and the second passage 22, so the above-mentioned exhaust gas backflow can be suppressed. Thus, exhaust gas is likely to flow from the first passage 21 and the second passage 22 to the scroll passage 18.

[0050] (3) The first face 21a is parallel to the second face 22a.

[0051] According to such a configuration, the amount of exhaust gas flowing adjacent to each other in the first exhaust flow El and the second exhaust flow E2 becomes large, so the Venturi effect becomes large.

[0052] (4) The flow passage cross-sectional areas of the portions of the first passage 21 and the second passage 22 adjacent to each other with the downstream portion 25 interposed therebetween are equal to each other.

[0053] According to such a configuration, since the flow passage cross-sectional area of the first passage 21 is equal to the flow passage cross-sectional area of the second passage 22, a difference between the force with which the first exhaust flow El assists the rotation of the turbine impeller 14 and the force with which the second exhaust flow E2 assists the rotation of the turbine impeller 14 is difficult to occur. Thus, the speed at which the turbine impeller 14 rotates is likely to be constant. Thus, a pulsation of the supercharging pressure is difficult to occur.

[0054] <Modification Example>

[0055] This embodiment can be implemented as follows. This embodiment and the following modified examples can be implemented in combination with each other within a range in which they are not technically contradictory.

[0056] • The cross-sectional area of the flow path of the first passage 21 and the cross-sectional area of the flow path of the second passage 22, which are adjacent to each other while sandwiching the downstream portion 25, can also be different from each other.

[0057] • In this specification, if the cross-sectional area of the flow path of the first passage 21 is assumed to be S1 and the cross-sectional area of the flow path of the second passage 22 is assumed to be S2, the case where S1 and S2 are equal includes the following case. That is, in addition to the case where S1 and S2 are completely identical, the case where 0.9 ≤ S1 / S2 ≤ 1.1 is satisfied is also included.

[0058] • The first upstream-side line segment 21c and the second upstream-side line segment 22c can also be parallel to each other.

[0059] • In this specification, "parallel" is not limited to strict parallel. That is, the case where the second downstream-side line segment 22b is inclined with respect to the first downstream-side line segment 21b within a range in which the flow direction of the first exhaust gas flow E1 and the flow direction of the second exhaust gas flow E2 can be regarded as parallel is also included in "parallel" in this specification.

Claims

1. A turbocharger, wherein the turbocharger is a turbocharger for an internal combustion engine, wherein, The internal combustion engine has the following features: The first cylinder and the second cylinder, whose combustion stroke is at a different time from that of the first cylinder; and The first exhaust port connected to the first cylinder and the second exhaust port connected to the second cylinder, The booster includes: Turbine impeller; Turbine casing, housing the turbine impeller; and A connecting pipe connects the turbine housing to the internal combustion engine. The connecting pipe has: The contact surface is in contact with the internal combustion engine. The first passage is connected to the first exhaust port; The second passage is connected to the second exhaust port; and A partition wall, extending from the contact surface, divides the interior of the connecting tube into the first passage and the second passage. The turbine housing has a vortex passage extending circumferentially along the turbine impeller between the inner wall of the turbine housing and the outer peripheral surface of the turbine impeller. The vortex tube passage connects the first passage and the second passage, so that the exhaust gas passing through the first passage and the exhaust gas passing through the second passage merge. The cross-sectional area with the largest flow path cross-section in the vortex tube passage, which is orthogonal to the rotation axis of the turbine impeller, is the specified cross-section. When observing the specified cross-section, The line segment extending upstream from the top of the partition wall toward the flow direction of the exhaust gas in the first passage, and defining the boundary between the first passage and the partition wall as the first downstream line segment, The line segment extending upstream from the top in the direction of exhaust flow within the second passage, and defining the boundary between the second passage and the partition wall, is the second downstream side line segment. The first downstream side segment is parallel to the second downstream side segment. The internal combustion engine has cylinders N1, N2, N3, and N4. The N1, N2, N3, and N4 cylinders are configured such that the combustion stroke occurs in this sequence. The first cylinder includes cylinder N1 and cylinder N3. The second cylinder includes the N2 cylinder and the N4 cylinder. The partition wall has a first surface containing the first downstream side segment and a second surface containing the second downstream side segment. The first surface is parallel to the second surface. The portion of the partition wall sandwiched between the first surface and the second surface is the downstream portion. When observing the specified cross-section, the flow path cross-sectional areas of the adjacent portions of the first and second passages, which sandwich the downstream portion, are equal. The partition wall has: The first upstream side segment is connected to the first downstream side segment and extends toward the contact surface in the connecting pipe; and The second upstream side segment connects to the second downstream side segment and extends toward the contact surface. When observing the specified cross-section The first upstream side segment is inclined relative to the second upstream side segment in such a way that the distance between the first upstream side segment and the second upstream side segment is wider the closer they are to the contact surface.

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