JP2017150322A - Exhaust adapter of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve an exhaust gas cooling performance in an exhaust adapter interposed between a cylinder head and an exhaust manifold. An exhaust adapter 3 has exhaust gas passages 24 to 27, and the exhaust gas passages 24 to 27 are sandwiched between upper and lower cooling water passages 38 and 39. The inlets 28 to 31 and the outlets 32 to 35 of the exhaust gas passages 24 to 27 are offset (shifted) in either direction when viewed from a direction orthogonal to the exhaust side surface 2a of the cylinder head 2. When the exhaust gas passages 24 to 27 are inclined or bent, the area of the inner surface of the exhaust gas passages 24 to 27 is increased, and the contact area of the exhaust gas is increased. Moreover, by changing the direction of the exhaust gas, the mixing property of the exhaust gas is enhanced, and the contactability of the exhaust gas to the inner surface of the exhaust gas passages 24 to 27 is also enhanced. As a result, the cooling performance of the exhaust gas can be significantly improved. [Selection diagram] Fig. 6

Description

  The present invention relates to an exhaust adapter interposed between a cylinder head of an internal combustion engine and an exhaust manifold.

  For example, in an internal combustion engine for a vehicle, in order to lower the temperature of exhaust gas and protect the exhaust gas purification catalyst, an exhaust adapter is disposed between the cylinder head and the exhaust manifold, and cooling water is passed through the exhaust adapter. It is known to lower the temperature of exhaust gas (in addition, the exhaust adapter can also contribute to an early temperature increase of the cooling water during the warm-up operation).

  In order to improve the exhaust gas cooling performance by the exhaust adapter, it can be said that the thickness of the exhaust adapter should be increased. However, this increases the weight of the internal combustion engine and deteriorates the fuel consumption. Therefore, it is considered to improve the cooling performance without increasing the thickness. As an example, in Patent Document 1, the exhaust gas passage of the exhaust adapter is tapered so that the cross-sectional area decreases from the inlet toward the outlet. In addition, it is disclosed that the cooling water passage has a configuration in which the cross-sectional area increases from the inlet side to the outlet side of the exhaust gas passage.

JP 2013-36448 A

  Patent Document 1 intends to efficiently cool the exhaust gas while suppressing the pressure loss on the outlet side by utilizing the fact that the volume is reduced when the exhaust gas is cooled. Exhaust gas exhausted from the port passes through the exhaust gas passage with straightness, so there is a concern that most of the exhaust gas will pass through without contacting the inner surface of the exhaust gas passage, and exhibits high cooling performance. I am wondering if I can do it.

  Further, if the exhaust gas cooling performance is low, the volume reduction rate of the exhaust gas is also low, so it can be said that whether the exhaust gas passes through the exhaust adapter without pressure loss remains.

  The present invention has been made to improve the current situation.

  The present invention is an exhaust adapter disposed between a cylinder head and an exhaust manifold, the exhaust adapter having an exhaust gas passage communicating with an exhaust port of the cylinder head and a branch pipe of the exhaust manifold. A cooling water passage for cooling the exhaust gas passage is formed, and the inlet and outlet of the exhaust gas passage are offset in either direction when viewed from the direction orthogonal to the exhaust side surface of the cylinder head. (Shifted).

  As an offset mode between the inlet and the outlet, as viewed from the direction perpendicular to the exhaust side of the cylinder head (direction perpendicular to the cylinder bore axis and the crank axis), it can be shifted in either the vertical direction or the horizontal direction, Arbitrary modes such as shifting in both directions can be adopted. It is also possible to make the offset modes of the plurality of exhaust gas passages different from each other.

  In the present invention, since the entrance and the exit of the exhaust gas passage are offset, the exhaust gas passage is inclined or bent inside the exhaust adapter. The surface area of the exhaust gas passage is larger than when concentrically arranged. Further, since the exhaust gas discharged from the exhaust port of the cylinder head changes direction in the exhaust gas passage, the mixing action of the exhaust gas occurs inside the exhaust gas passage, and the contact property of the exhaust gas with the inner surface of the exhaust gas passage is Increase dramatically.

  As described above, the increase in the surface area of the exhaust gas passage and the increase in the contact property of the exhaust gas to the inner surface of the exhaust gas passage significantly increase the exhaust gas without increasing the thickness of the exhaust adapter. Coolability can be improved. In addition, the temperature of the exhaust gas can be made uniform.

  In addition, since it is possible to easily impart a swirl flow to the exhaust gas by utilizing the direction change of the exhaust gas, it is possible to enhance the mixing property of the exhaust gas and further promote the uniformity of the temperature of the exhaust gas. As a result, the burden on the exhaust gas purification catalyst can be reduced and the durability can be improved. The ability to impart a swirl flow to the exhaust gas also contributes to a smoother exhaust gas flow. As a result, not only can pressure pressure be suppressed to improve fuel efficiency, but also vehicle acceleration response. It can also contribute to improvement.

It is the side view which looked at the principal part of the internal combustion engine which concerns on embodiment from the direction orthogonal to a crankshaft axis and a cylinder bore axis. It is a right view of FIG. FIG. FIG. It is the figure which looked at the exhaust adapter from the back side. (A) is a sectional view taken along the line VIA-VIA in FIG. 5, and (B) is a schematic diagram showing the flow of exhaust gas.

(1). Outline of Internal Combustion Engine Next, an embodiment of the present invention will be described with reference to the drawings. In this embodiment, the state seen from the crank axis direction is defined as a front view. Accordingly, FIG. 1 is a side view seen from the direction of the crank axis (cam axis direction) and the direction perpendicular to the cylinder bore axis. As a precaution, the directions are shown in FIG. First, an outline of the internal combustion engine will be described.

  The internal combustion engine of the present embodiment is for a vehicle (for automobiles), and has a cylinder block 1 provided with a cylinder bore (not shown) and a cylinder head 2 fixed to the upper surface thereof as in the conventional case. An exhaust manifold 4 is fixed to the exhaust side surface 2 a of the cylinder head 2 via a cast exhaust adapter 3. The internal combustion engine has four cylinders. Therefore, as shown in FIG. 3, first to fourth exhaust ports 5 to 8 are opened in a line on the exhaust side surface 2 a of the cylinder head 2 in order from the end. Yes. Each exhaust port 5, 6, 7 and 8 has an oblong shape in the longitudinal direction.

  The exhaust manifold 4 has first to fourth four branch pipes 9 to 12 corresponding to the four exhaust ports 5 to 8, and the start ends of the branch pipes 9, 10, 11 and 12 are flange plates. It is fixed to 4a. The first branch pipe 9 and the fourth branch pipes 9 and 12 are gathered in the first collecting pipe 13, and the second branch pipe 10 and the third branch pipe 11 are gathered in the second collecting pipe 14. These two collecting pipes 13 and 14 are connected to the upper end of the catalyst case 15.

  The first branch pipe 9 and the fourth branch pipe 12 are connected to the first assembly 13 via a three-way joint 16, and the second branch pipe 10 is welded to the middle portion of the third branch pipe 11. . Therefore, the second collecting pipe 14 is constituted by the terminal portion of the third branch pipe 11. In addition, although the exhaust manifold 4 of the embodiment is manufactured by welding pipes, a cast product may be adopted.

  The catalyst case 15 has a straight portion in which the three-way catalyst is stored, and the upper portion is an upper cone portion 17 that is narrowed upward (lower portion), and the lower portion is a lower cone portion 18 that is narrowed. ing. A straight exhaust connection pipe 19 is connected to the lower end of the lower cone portion 18, and a fixing bracket 20 is integrally fixed to the exhaust connection pipe 19. The lower cone portion 18 is connected to an EGR pipe 21 for returning a part of the exhaust gas to the intake system.

  The two collecting pipes 13 and 14 are arranged in the left-right direction orthogonal to the exhaust side surface 2 a of the cylinder head 2. Therefore, the upper end portion of the upper cone portion 15b of the catalyst case 15 has a shape that is long in the left-right direction, and the two collecting pipes 13 and 14 are connected to the upper end portion. Therefore, the lower end of the upper cone portion 17 is circular, but the upper end is oval. Therefore, although the upper cone portion 17 is generally constricted, the degree of constriction displayed in the side view of FIG. 1 is a tighter angle than the degree of constriction shown in FIG. ing.

  In other words, the left and right surfaces of the upper cone portion 17 are gently inclined surfaces 17b, and the front and rear surfaces are steeply inclined surfaces 17a. The two inclined surfaces 17a and 17b converge in a circle toward the lower end. Yes. The hollow boss 22 is fixed to one steeply inclined surface 17a by welding, and an AF sensor (air-fuel ratio sensor) is attached to the hollow boss 22 by screwing.

(2). Structure of the exhaust adapter The exhaust adapter 3 is a thick plate or block and has a long front and rear appearance, and corresponds to the first to fourth exhaust ports 5 to 8, as shown in FIG. The first to fourth exhaust gas passages 24 to 27 are provided. Accordingly, the exhaust adapter 3 includes first to fourth inlets 28 to 31 corresponding to the exhaust ports 5 to 8 and first to fourth outlets 32 to 32 corresponding to the first to fourth branch pipes 9 to 12. 35.

  Each of the inlets 28 to 31 has the same oval shape as the exhaust ports 5 to 8, while each of the outlets 32 to 35 has the same circular shape as that of each of the branch pipes 9 to 12. It is slightly smaller toward ~ 35.

  Further, as clearly shown in FIG. 5, the inlets 28 to 31 and the outlets 32 to 35 of the exhaust gas passages 24 to 27 are arranged in the vertical direction so that the outlets 32 to 35 are higher than the inlets 28 to 31. The outlets 32 to 35 are displaced (offset) in the front-rear direction (crank axis direction) with respect to the inlets 28 to 31 as well as being displaced (offset) in the axial direction of the cylinder bore.

  In this case, the second outlet 33 and the third outlet 34 are almost the same height and higher than the first outlet 32 and the fourth outlet 35. The first outlet 32 and the fourth outlet 35 have substantially the same height. Further, the left and right shift amounts of the inlets 28 to 31 and the outlets 32 to 35 in the exhaust gas passages 24 to 27 are not uniform but different. In addition, the inlets 28 to 30 and the outlets 32 to 34 in the first to third exhaust gas passages 24 to 27 are shifted in the same direction, but the inlet 31 and the outlet 35 of the fourth exhaust gas passage 28 are opposite. It is displaced in the direction.

  As described above, the difference in the displacement between the inlets 28 to 31 and the outlets 32 to 35 in the exhaust gas passages 24 to 27 is due to the form of the branch pipes 9, 10, 11, and 12. For example, the catalyst case 15 may be brought close to the end of the cylinder head 2, but in this case, the positions of the collecting pipes 13 and 14 change, so that the inlets 28 to 31 and the outlets 32 to 32 in the exhaust gas passages 24 to 27 are changed. The deviation from 35 also changes.

  As shown by the second exhaust gas passage 25 as a representative in FIG. 6A, each of the exhaust gas passages 24 to 27 has a straight portion 36, a vicinity of the inlets 28 to 31 and a vicinity of the outlets 32 to 35. 37, the part connecting the two is bent (or inclined). Actually, the bend is not two-dimensional but three-dimensional, and it is possible to adopt a spiral bend.

  An upper cooling water passage 38 and a lower cooling water passage 39 are formed inside the exhaust adapter 3 with the exhaust gas passages 24 to 27 interposed therebetween, and both the cooling water passages 38 and 39 are formed as a first exhaust gas passage. It communicates outside 24. A cooling water inlet 40 is provided at the end of the lower cooling water passage 39, and a cooling water outlet 41 is provided at the end of the upper cooling water passage 38. Accordingly, the cooling water enters the exhaust adapter 3 from below, makes a U-turn, flows into the upper cooling water passage 38, and then is discharged from the cooling water outlet 41.

  The exhaust adapter 3 is fixed to the cylinder head 2 with stat bolts and nuts (both not shown) at the five first mounting holes 42 indicated by black circles in FIG. In the exhaust manifold 4, flanges 4a are fixed to the exhaust adapter 3 with bolts (not shown) at the seven second mounting holes 43 shown by hatching in FIGS. Therefore, the second mounting hole 43 of the exhaust adapter 3 is a tapped hole.

(3) Summary The exhaust gas from the exhaust ports 5, 6, 7 and 8 of the cylinder head 2 is cooled by the cooling water in the process of passing through the exhaust gas passages 24 to 27 of the exhaust adapter 3. Thereby, the temperature of exhaust gas can be reduced and damage to the catalyst can be prevented.

  In this embodiment, since the inlets 28 to 31 and the outlets 32 to 35 of the exhaust gas passages 24 to 27 are shifted (offset), the lengths of the exhaust gas passages 24 to 27 are increased. As a result, the exhaust gas contact area is increased, and the exhaust gas flowing into the exhaust gas passages 24 to 27 with straightness is changed in direction so that the exhaust gas contacts the inner surfaces of the exhaust gas passages 24 to 27. Increases nature. For this reason, high cooling performance is demonstrated.

  Since the exhaust gas passages 24 to 27 are bent and the length is increased, the contact area between the exhaust gas passages 24 to 27 and the cooling water also increases. Also in this aspect, the exhaust gas is excellent in cooling performance.

  Further, since the direction of the exhaust gas is changed in the exhaust gas passages 24 to 27, the exhaust gas receives a strong stirring action, so that the temperature of the exhaust gas flowing into the catalyst case 15 is made uniform to prevent the catalyst from being damaged. Or it can suppress remarkably and can also suppress the thermal distortion of the branch pipes 9, 10, 11, and 12.

  Further, since the inlets 28 to 31 and the outlets 32 to 35 of the exhaust gas passages 24 to 27 are shifted in both the front-rear direction and the vertical direction, as shown schematically in FIG. The gas tends to swirl around the axis of the exhaust gas passages 24 to 27, thereby improving the contact property of the exhaust gas to the inner surfaces of the exhaust gas passages 24 to 27 and the mixing property of the exhaust gas. Thus, it is possible to promote cooling and temperature uniformity.

  That is, the inner surfaces of the exhaust gas passages 24 to 27 are arcuately curved, and the exhaust gas passages 24 to 27 are inclined upward in the straight direction from the exhaust ports 5, 6, 7, 8. Because of the conversion, the exhaust gas is changed in the upward direction and the front-rear direction while being guided by the inner surfaces of the exhaust gas passages 24-27, so that the exhaust gas has a smooth curved surface in the exhaust gas passages 24-27. It is guided and changes its direction around the axis of the exhaust gas passages 24-27, and as a result, it can be said that a swirl flow is formed. If the exhaust gas passages 24 to 27 are formed in a spiral shape, a strong swirl flow can be reliably imparted to the exhaust gas.

  The swirling flow imparted to the exhaust gas also means that the exhaust gas contacts the exhaust gas passages 24 to 27 and the inner surfaces of the branch pipes 9, 10, 11 and 12 evenly. The thermal distortion of the adapter 3 and the branch pipes 9, 10, 11, and 12 can be suppressed to contribute to prevention of breakage.

  Each branch pipe 9, 10, 11, 12 is bent downward from a substantially horizontal direction orthogonal to the outer surface of the exhaust adapter 3, but each branch pipe 9, 10, 11, 12 is a collecting pipe 13, 14. Therefore, even in the process in which the exhaust gas flows from the start end to the end of the branch pipes 9, 10, 11, 12, the exhaust gas swirls around the axis of each branch pipe 9, 10, 11, 12. It can be said that it shows a tendency.

  That is, since the branch pipes 9, 10, 11, and 12 are bent downward in a state of approaching the front and rear intermediate portions of the exhaust adapter 3, the straightness with respect to the start ends of the branch pipes 9, 10, 11, and 12 is improved. The exhaust gas that flows in and flows toward the end while being guided by the inner surfaces of the branch pipes 9, 10, 11, 12, is because the branch pipes 9, 10, 11, 12 are bent in plan view, It can be said that the exhaust gas goes to the catalyst case 15 while turning around the axis of the branch pipes 9, 10, 11, and 12.

  In the present embodiment, the straight portions 36 and 37 are provided in the portions of the inlets 28 to 31 and the outlets 32 to 35 of the exhaust gas passages 24 to 27. When the straight portions 36 and 37 are provided in this way, Since the lengths of the exhaust gas passages 24 to 27 can be further increased, the cooling performance can be further improved. Moreover, since the flow of the exhaust gas is smoothly guided by the presence of the straight portion 36 on the entrance side, the exhaust gas is prevented from excessively hitting a specific portion near the entrance of the exhaust gas passages 24-27, The heat damage of the exhaust adapter 3 can also be prevented.

  Further, the straight portion 37 on the outlet side is substantially parallel to the start end portion of each branch pipe 9, 10, 11, 12, so that the exhaust gas is strongly applied to a part of the inner surface of the branch pipe 9, 10, 11, 12. It can suppress hitting. Thereby, the thermal distortion of the branch pipes 9, 10, 11, and 12 can be suppressed, and adverse effects such as breakage can be prevented.

  The exhaust adapter 3 can also make the outlets 32-35 lower than the inlets 28-31. However, if the outlets 32-35 are made higher than the inlets 28-31 as in the embodiment, the exhaust gas passages 24- Even if condensed water is generated in 27, there is an advantage that the generated condensed water can be prevented from dripping onto the catalyst. Further, since heat has a property of escaping upward, if the exhaust gas passages 24 to 27 are inclined upward as in the embodiment, it is possible to contribute to suppression of thermal distortion of the exhaust adapter 3.

  As shown in FIG. 6, the cooling water passages 38 and 39 have a larger cross-sectional area on the outlet side of the exhaust gas passages 24 to 27. For this reason, the exhaust gas passages 24 to 27 are strongly cooled at portions where the exhaust gas strikes strongly. Also in this aspect, the cooling performance is excellent.

  The embodiment of the present invention has been described above, but the present invention can be embodied in various ways. For example, the number of cylinders of the internal combustion engine is not limited to four, and can be applied to other multi-cylinder internal combustion engines. It is not always necessary to provide a straight portion in the exhaust gas passage, and a straight portion may be provided only at the inlet portion or only at the outlet portion. Each exhaust gas passage may be formed in the same displacement manner.

  The present invention can actually be embodied in an exhaust adapter of an internal combustion engine. Therefore, it can be used industrially.

2 Cylinder Head 2a Exhaust Side 3 Exhaust Adapter 4 Exhaust Manifold 5-8 Exhaust Port 9-12 Exhaust Manifold Branch Pipe 13, 14 Exhaust Manifold Collecting Pipe 15 Catalyst Case 24-27 Exhaust Gas Passage 28-31 Inside Exhaust Adapter Gas passage entrance 32 to 35 Exhaust gas passage exit 36, 37 Straight section 38, 39 Cooling water passage

Claims (1)

An exhaust adapter disposed between the cylinder head and the exhaust manifold,
An exhaust gas passage communicating with the exhaust port of the cylinder head and the branch pipe of the exhaust manifold, and a cooling water passage for cooling the exhaust gas passage are formed inside,
The inlet and outlet of the exhaust gas passage are offset in either direction as seen from the direction orthogonal to the exhaust side of the cylinder head,
Exhaust adapter for internal combustion engines.

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