JP3572751B2 - Double structure exhaust manifold - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to a seal structure for an engine-side gap of an exhaust manifold formed in a double pipe structure, which is connected to an engine and a catalyst for purifying exhaust gas of the engine, has an inner pipe cast therein, and has a double pipe structure.
[0002]
[Prior art]
2. Description of the Related Art In automobiles, a catalyst is disposed downstream of an exhaust pipe to purify exhaust gas. In this case, when the engine is started, a problem occurs in terms of purification efficiency. When the engine is started, both the catalyst and the exhaust gas are at a low temperature. Therefore, since the catalyst temperature does not reach the activation temperature, a chemical change does not occur, and a situation occurs in which the unburned components in the exhaust gas are not sufficiently reacted.
[0003]
In order to cope with this, a double-pipe exhaust manifold for keeping the exhaust gas warm has been proposed. In the double pipe exhaust manifold, the inner pipe is concentrically arranged with a gap inside the outer pipe, and a hollow heat insulating layer is secured between the outer pipe and the inner pipe.
[0004]
The double pipe exhaust manifold can reduce the heat capacity of the exhaust gas contact portion by securing the structural strength of the outer pipe and reducing the thickness of the inner pipe constituting the exhaust gas passage as much as possible. . In addition, since the hollow heat insulating layer is provided between the inner pipe and the outer pipe, the escape of heat through the outer pipe can be reduced. Therefore, when the engine is started, the temperature of the inner wall of the exhaust manifold can be quickly increased, and the effect of keeping the exhaust gas warm can be enhanced.
[0005]
However, in a structure in which an outer tube formed by pressing a plate material such as a stainless steel material and covering a thin inner tube, it is necessary to use an expensive material so that the plate material of the outer tube is not corroded by salt damage or the like. Further, since there is a possibility that the exhaust gas leaks to the outside air from the mating surface of the two welded plate members, a leak test using compressed air and reworking occur, which makes the product expensive. For this reason, Japanese Patent Application Laid-Open No. 63-215803 discloses a prior art of a double pipe structure in which an inner pipe is cast with cast iron.
[0006]
Also, in the case of a dual-structure exhaust manifold, if exhaust gas leaks into the gap between the inner pipe and the outer cylinder, the temperature of the exhaust gas decreases, so it is necessary to seal the gap between the inner pipe and the outer cylinder. Since a large temperature difference occurs between the outer tube and the outer tube, a structure must be adopted in which the inner tube is held by the outer tube while absorbing the thermal expansion of both.
[0007]
Conventionally, examples of such a structure are shown in FIGS.
[0008]
In FIG. 9, a double pipe exhaust manifold is formed by bending the distal end portion 921 of the inner pipe 902 toward the outer cylinder 901 and casting the inner pipe 902 with cast iron or the like.
[0009]
FIG. 10 shows a structure in which the inner pipe 1002 is held by the support 1022 and the support 1022 is cast with cast iron or the like.
[0010]
FIG. 11 shows a structure in which an inner pipe 1102 that is not bent toward the outer cylinder is cast with cast iron or the like.
[0011]
[Problems to be solved by the invention]
By the way, in the inner pipe cast dual structure exhaust manifold shown in FIG. 9, a stainless steel material which is unlikely to deteriorate at high temperature even when exposed to high temperature exhaust gas is provided on the outer cylinder 901 side to expand the bending diameter. 902 needs to be thicker. Further, a hole 920 for sand removal of a sand mold when the inner pipe 902 is cast is provided. After the sand removal processing is completed, sand removal is performed so that exhaust gas does not leak to the outside air from a gap 931 between the inner pipe 902 and the outer cylinder 901. Hole 920 needs to be sealed. In addition, at the bent portion of the inner tube 920 and the portion of the outer tube 901, it is difficult to remove sand in the sand mold, so it is necessary to add a step of sand removal such as air blow.
[0012]
In the exhaust manifold in which the inner pipe is cast as shown in FIG. 10, since the inner pipe 1002 is held by the support 1022, it is not necessary to increase the diameter of the inner pipe 1002, and the inner pipe 1002 can be made thinner. However, a sand mold hole 1020 is provided in the sand mold at the time of casting the inner tube 1002, and after the sand removal process is completed, the sand removal is performed so that the exhaust gas does not leak to the outside air from the gap 1031 between the inner tube 1002 and the outer tube 1001. The hole 1020 needs to be sealed. It is the same as in FIG. 9 that the sand of the sand mold between the support 1022 and the outer cylinder 1001 is hardly removed.
[0013]
In the exhaust manifold with a double-structured inner pipe shown in FIG. 11, since the tip of the inner pipe 1102 is cast while the inner pipe 1102 is in a cylindrical shape, no support parts are required. Since it is not necessary to increase the diameter of the tube 1102, the thickness of the inner tube 1102 can be reduced. However, it is necessary to provide a sand mold hole 1120, and after the sand removal process is completed, seal the sand hole 1120 so that the exhaust gas does not leak to the outside air from the gap 1131 between the inner tube 1102 and the outer tube 1101. is there. It is the same as FIG. 9 that the sand-type sand in the gap between the inner tube 1102 and the outer tube 1101 is hardly removed at the portion where the inner tube 1102 is cast.
[0014]
The present invention has been made in consideration of the above circumstances, and in a dual-structure exhaust manifold that is manufactured at a low cost by casting an inner pipe with cast iron, it is possible to improve the temperature rise characteristic of exhaust gas at the time of engine start, and Another object of the present invention is to provide an engine dual structure exhaust manifold that can reliably absorb a difference in thermal expansion between an outer pipe and an inner pipe.
[0015]
[Means for Solving the Problems]
The invention according to claim 1 is a double-walled exhaust manifold for an engine in which a thin inner tube made of stainless steel is cast with cast iron, and the inside of the inner tube is used as an exhaust gas passage. Then, one end of the band-shaped plate material is welded and fixed to the outer tube side of the inner tube, the other end extends toward the outer tube in an R shape from the inner tube, and the tip is cast and fixed to the outer tube. The holding member and the engine-side tip of the inner pipe have a diameter that is expanded toward the outer cylinder, and the expanded portion of the inner pipe has a diameter that is larger than the inner diameter of the exhaust port of the engine at the end face of the flange portion. The tip of the pipe and the engine-side flange of the exhaust manifold are formed on the same surface, and the tip of the engine-side radial expansion of the inner pipe, and the inner pipe, which is welded and fixed to the inner pipe, of the inner pipe On the downstream side of the holding member, A gasket that seals an exhaust gas between an engine head and the exhaust manifold, and a thermal expansion absorbing structure of the inner tube in which a part of the inner tube expands in an R-shaped convex shape toward the outer cylinder side. And a gasket having a hole smaller than the inner diameter of the radially expanded portion of the inner tube.
[0016]
According to a second aspect of the present invention, there is provided the dual-structure exhaust manifold according to the first aspect, wherein the engine-side tip of the inner pipe is located inside the engine-side flange surface of the exhaust manifold without expanding the inner diameter. A pipe and the gasket are formed of a metal such as stainless steel, and the inside of the gasket has a cylindrical portion bent toward the exhaust manifold, and the cylindrical portion is mounted between the exhaust manifold and an engine. It has a gasket attached to the outer circumference of the inner tube.
[0017]
According to a third aspect of the present invention, there is provided the dual-structure exhaust manifold according to the first aspect, wherein a diameter of the inner pipe at an engine-side tip portion is increased toward the engine side, and a tip of the inner pipe is connected to the engine side. An inner pipe located on the inner side of the flange surface, and the gasket is formed of a metal such as stainless steel, and has a cylindrical portion obtained by bending the inside of the gasket to the exhaust manifold side, and the cylindrical portion has a diameter toward the inside of the exhaust manifold. And a gasket mounted inside the radially expanded portion of the inner pipe in a state where the gasket is mounted between the exhaust manifold and an engine.
[0018]
According to a fourth aspect of the present invention, there is provided the dual-structure exhaust manifold according to the first aspect, wherein the engine-side tip portion of the inner pipe is located closer to the engine than the engine-side flange surface of the exhaust manifold without expanding the inner diameter. A first gasket for sealing exhaust gas tightly attached to the outer periphery of the inner pipe and the flange of the exhaust manifold, between the inner pipe, the flange of the exhaust manifold, and the engine, and a hole larger than the inner diameter of the exhaust port of the engine. A second gasket that is in close contact with the engine, and a hole between the first gasket and the second gasket that is larger than the outer diameter of the inner pipe; It is characterized by having a support with a thickness located inside.
[0019]
The invention according to claim 5 is the dual structure exhaust manifold according to claim 4, wherein the support member has a hole smaller than the inner pipe, and forms a U-shaped groove on the exhaust manifold side over the entire circumference. The tip of the inner tube on the engine side is inserted into the U-shaped groove.
[0020]
According to a sixth aspect of the present invention, there is provided the dual-structure exhaust manifold according to the first aspect, wherein the gasket is formed of a metal such as stainless steel.
[0021]
The invention according to claim 7 is the dual structure exhaust manifold according to claim 1, wherein the inner pipe is located downstream of the inner pipe holding member welded and fixed to the inner pipe, toward the outer cylinder. And a plurality of inner pipes having a plurality of thermal expansion absorbing structures for expanding the inner pipe in an R-shaped convex shape.
[0022]
An eighth aspect of the present invention is the dual structure exhaust manifold according to the first aspect, wherein the inner pipe holding member is fixed to the outer periphery of the inner pipe by spot welding.
[0023]
According to a ninth aspect of the present invention, there is provided the dual-structure exhaust manifold according to the second aspect, wherein an engine-side flange portion of the exhaust manifold is formed of a metal material such as stainless steel in a cylindrical shape, and the outer periphery is formed by casting the exhaust manifold. Sometimes the inner surface is narrowed down from the flange surface toward the inside of the exhaust manifold, where the diameter is the smallest, larger than the inner pipe of the dual structure exhaust manifold, and inside the engine-side tip of the inner pipe. The ring support has a length of up to, the inner surface is machined smoothly, and the engine side surface is machined to the same surface as the flange surface of the exhaust manifold, or is cast into the inside of the exhaust manifold. And the smallest inner diameter of the ring support and the outer diameter of the inner tube A metal ring gasket having an outer diameter of a core larger than the gap of the engine, with the exhaust manifold attached to the engine, the ring gasket is formed by an outer periphery of the inner pipe, an inner surface of the ring support, and an engine flange. It is characterized in that it is mounted tightly between the surface.
[0024]
According to a tenth aspect of the present invention, there is provided the dual-structure exhaust manifold according to the second aspect, wherein a part of the inner pipe, which is formed at an engine-side tip portion of the inner pipe toward the outer cylinder, is formed by R. In the thermal expansion absorbing structure of the inner tube bulging into a convex shape, and in the engine side flange portion of the exhaust manifold, the inner surface was machined so that the inner diameter became smaller from the engine side smooth surface of the flange toward the inside of the exhaust manifold. A flange smooth cut portion, a metal ring gasket having a core outer diameter larger than a gap between the smallest inner diameter of the flange smooth cut portion and the outer diameter of the inner pipe, and a state in which the exhaust manifold is attached to an engine; The ring gasket may be an outer periphery of an engine-side tip portion of the inner tube, or a convex portion of a thermal expansion absorbing structure of the inner tube. An outer peripheral, said flange smoothing cutting unit, characterized in that it is tightly fitted between the flange surface of the engine.
[0025]
According to the eleventh aspect of the present invention, there is provided the dual-structure exhaust manifold according to the tenth aspect, wherein the thermal expansion absorbing structure is not provided in the inner pipe on the engine side from the inner pipe holding member welded and fixed to the inner pipe. An inner pipe located inside the exhaust manifold from the engine-side flange surface of the exhaust manifold, and the ring gasket having the exhaust manifold attached to the engine, the ring gasket having an outer periphery of an engine-side tip portion of the inner pipe, and the flange having a smooth cut. And a flange portion of the engine.
[0026]
According to a twelfth aspect of the present invention, there is provided the dual-structure exhaust manifold according to the ninth aspect, wherein the diameter of the inner pipe is reduced toward the engine at the tip of the inner pipe toward the engine. A tip end of reduction and a ring support whose inner surface is narrowed inward from the flange surface toward the inside of the exhaust manifold.In a state where the exhaust manifold is attached to an engine, the ring gasket reduces the diameter of the inner pipe. It is characterized in that it is densely mounted between the outer periphery of the distal end portion, the inner surface of the ring support, and the flange surface of the engine.
[0027]
The invention of claim 13The engine has a double-walled exhaust manifold having an inner pipe formed thinly of stainless steel and an outer cylinder made of cast iron surrounding the outer circumference of the inner pipe, and having the inner pipe as a passage for exhaust gas. A part of the engine-side tip of the inner pipe is expanded to the outer cylinder side in a convex shape of an R shape to form a thermal expansion absorbing structure of the inner pipe, and a space between the engine head and the exhaust manifold is formed. An engine side gasket for sealing exhaust gas and a front tube side gasket for sealing exhaust gas between the exhaust manifold and the front tube are formed of metal such as stainless steel, and these engine side gasket and front tube side are formed. The inner diameter of the gasket is formed smaller than the inner diameter of the thermal expansion absorbing structure, and the gasket is mounted on the outer circumference of the inner tube. The outer diameter of the outer cylinder on the engine side is formed larger than the exhaust port of the engine, the outer diameter of the outer cylinder on the front tube side is formed larger than the diameter of the front tube, and the outer cylinder has an engine side flange. An engine manifold gasket and a front tube gasket are provided on the exhaust manifold side flange with a flat flanged flat cut portion having an inner diameter gradually reduced so that the engine and the front tube are mounted on the exhaust manifold. However, it is characterized in that it is configured to be in close contact with the outer periphery of the inner tube, the flange smooth cut portion, the flange surface of the engine or the flange surface of the front tube, respectively.
[0029]
[Action]
According to the first aspect of the present invention, a core for forming a gap between the inner tube and the outer tube used when casting the inner tube and the inner tube holding member is provided with a gap between the inner tube and the outer tube. Since it is possible to extract the core from the communicating portion, it is not necessary to provide a sand hole for extracting the core sand, thereby improving workability and preventing the core from remaining between the inner tube and the outer cylinder.
[0030]
Further, since the thickness of the inner tube can be reduced, the heat capacity of the inner tube is small, and the wall temperature of the inner tube rises early. Therefore, the amount of heat transfer from the exhaust gas to the inner pipe is suppressed low, and the temperature of the exhaust gas is suppressed from decreasing. As a result, the temperature of the inlet gas of the catalyst installed behind the exhaust manifold can be increased.
[0031]
In addition, since the gap between the inner tube and the outer cylinder is closed by the gasket, it is possible to prevent the exhaust gas from flowing into the gap between the inner tube and the outer cylinder, and it is possible to suppress a decrease in the exhaust gas temperature.
[0032]
When the temperature is high, the position of the inner pipe on the engine side is fixed by the inner pipe holding member, and the diameter of the inner pipe is expanded toward the outer cylinder. By absorbing in the direction, the tip can be prevented from being damaged, and furthermore, the thermal expansion absorbing structure provided on the downstream side of the inner tube holding member absorbs the expansion caused by the thermal expansion of the inner tube downstream of the inner tube holding member, Prevents damage to the inner tube.
[0033]
According to the second aspect of the present invention, since the cylindrical portion of the metal gasket is mounted on the outer periphery of the inner tube, it is possible to prevent the exhaust gas from flowing into the gap between the inner tube and the outer tube, and to suppress a decrease in the temperature of the exhaust gas. .
[0034]
Further, at high temperatures, the expansion due to thermal expansion of the inner pipe on the engine side from the inner pipe holding member welded and fixed to the inner pipe is absorbed by the cylindrical portion of the metal gasket, so that damage to the inner pipe can be prevented.
[0035]
According to the third aspect of the invention, since the cylindrical portion of the metal gasket is mounted inside the inner tube, it is possible to prevent the exhaust gas from flowing into the gap between the inner tube and the outer tube, and to suppress a decrease in the temperature of the exhaust gas. .
[0036]
In addition, at high temperatures, the expansion due to thermal expansion of the inner pipe on the engine side from the inner pipe holding member welded and fixed to the inner pipe is absorbed by the diameter expansion portion of the inner pipe and the cylindrical portion of the metal gasket. Pipe breakage can be prevented.
[0037]
According to the fourth aspect of the present invention, the first gasket prevents the exhaust gas from leaking into the gap between the inner tube and the outer cylinder without expanding the engine-side tip of the inner tube or bending the gasket. Suppress temperature drop. In addition, the support member can absorb the elongation of the inner tube at high temperature and prevent the inner tube from being damaged.
[0038]
According to the invention of claim 5, deterioration of the gasket due to the exhaust gas coming into contact with the first gasket for preventing the exhaust gas from leaking into the gap between the inner pipe and the outer cylinder for a long time can be suppressed, and high temperature resistance and oxidation resistance can be suppressed. It does not need to be a sex material.
[0039]
According to the sixth aspect of the invention, the elongation of the tip of the inner tube is suppressed by the metal gasket, so that the occurrence of scratches on the engine side due to the inner tube can be suppressed.
[0040]
According to the invention of claim 7, it is possible to prevent the deterioration of the inner tube holding member due to the expansion of the thermal expansion of the inner tube at a high temperature.
[0041]
According to the eighth aspect of the present invention, the inner tube holding member can be easily fixed by welding, the heat capacity of the member directly in contact with the inner tube can be reduced, and the temperature of the exhaust gas can be increased quickly.
[0042]
According to the ninth aspect of the present invention, the gap between the outer cylinder and the inner pipe of the exhaust manifold, and the space between the flange surface of the outer cylinder and the engine are sealed with a ring gasket, so that the exhaust gas is dissipated outside the exhaust manifold, and And the outer cylinder can be prevented from flowing into the gap, and the positioning of the inner pipe becomes easier when the exhaust manifold is attached to the engine.
[0043]
Further, by using a ring support separate from the exhaust manifold body, the diameter of the ring gasket can be reduced. Further, since the inner diameter of the ring support is sufficiently larger than the outer diameter of the inner tube, sand removal after casting is easy.
[0044]
According to the tenth aspect of the present invention, since the R portion of the thermal expansion absorbing structure of the inner tube and the smooth cut portion of the flange of the exhaust manifold are sealed with a ring gasket, a separate ring support is not required.
[0045]
According to the eleventh aspect of the present invention, the distal end of the cylindrical inner tube and the smooth cut portion of the flange of the exhaust manifold are sealed with a large-diameter ring gasket, so that a separate ring support or heat at the distal end of the inner tube is used. No expansion absorbing structure is required.
[0046]
According to the twelfth aspect of the present invention, the diameter of the distal end of the inner pipe is reduced toward the engine, and a ring support separate from the exhaust manifold reduces the inner diameter toward the inside of the exhaust manifold. The mounting of the ring gasket becomes easy.
[0047]
According to the thirteenth aspect, on the front tube side of the exhaust manifold, a gap between the inner tube and the outer tube and a space between the outer tube and the front tube are formed.Front tube sideSince the gasket is used for sealing, the positioning and holding of the inner tube are facilitated, and the holding member for the inner tube is not required at the engine-side flange portion.In addition, the engine-side gasket prevents the exhaust gas from leaking into the gap between the inner tube and the outer cylinder without processing the expansion or contraction of the engine-side tip of the inner tube, and suppresses a decrease in the exhaust gas temperature.
[0049]
【Example】
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0050]
FIG. 1 is an external view of an exhaust manifold according to the present invention. 2 is a cross-sectional view of the exhaust manifold according to the present invention before machining the flange surface of the engine-side flange portion, and a cross-sectional view on the right side of FIG. 2 is a cross section taken along line II. FIG. FIG.
[0051]
[Example 1]
The inner tube 302 is exposed to high-temperature exhaust gas during high-speed running and the like, and is formed to be thin (for example, 0.5 mm) using a stainless material in order to prevent deterioration due to oxidation and corrosion. The inner pipe 302 is formed into an exhaust manifold by press working or pipe bending. The diameter of the engine-side tip 305 of the inner pipe is expanded toward the outer cylinder 301, and the diameter of the tip 305 of the inner pipe is larger than the diameter of the exhaust port of the engine at the surface of the flange 303. I have. A plurality of inner tube holding members 304 formed of a band-shaped plate are welded and fixed to the outer periphery of the inner tube 302 near the flange 303 of the inner tube 302. The inner tube holding member 304 is formed in an R shape from the inner tube 302 toward the outer tube 301, and the tip is cast into the outer tube 301.
[0052]
On the downstream side of the portion of the inner tube 302 to which the inner tube holding member 304 is welded, a thermal expansion absorbing portion 310 that protrudes toward the outer tube 301 is formed. The size of the hole of the gasket 311 for sealing the exhaust gas between the exhaust manifold and the engine so that the exhaust gas does not leak outside is larger than the inner diameter of the engine-side tip portion 305 of the inner pipe 302. On the downstream side of the inner tube 302, a thermal expansion absorbing portion 310 swelling convexly toward the outer cylinder side is appropriately formed.
[0053]
A structure for preventing the exhaust gas containing the stiffness and strength of the entire exhaust pipe and harmful components from leaking to the outside air is formed by an outer cylinder 301 which is formed by casting the inner pipe 302. Therefore, the outer cylinder 301 itself has a function of an exhaust manifold conventionally mounted on an automobile engine. Further, the inner tube 302 and the outer tube 301 have an appropriate gap (for example, about 3 mm to 5 mm), and the inner tube 302 is not directly fixed to the outer tube 301. The outer cylinder 301 is formed integrally with the engine side flange 303 and the front tube side flange (not shown).
[0054]
When the distal end of the inner tube 302 and the inner tube holding member 304 welded and fixed to the inner tube 302 is cast into a double tube shape, a core is inserted into a gap between the inner tube 302 and the outer tube 301 to be cast. become. After the casting is completed, the core sand is removed, but when the core sand is left in the gap between the inner tube 302 and the outer tube 301, the core sand is removed from the catalyst installed behind the exhaust pipe (not shown). As a result, the performance of the catalyst may be reduced, exhaust gas purification efficiency may be reduced, and harmful exhaust gas may be released to the outside air. In the exhaust manifold having the double pipe structure according to the present embodiment, since core sand for forming the gap 331 can be extracted from the gap 331 between the outer cylinder 301 and the inner pipe 302, a new sand hole needs to be provided. In addition, since the sand is removed at the end of the core, the core sand is easily removed from the gap 331, and the core sand does not remain in the gap. Further, since the inner pipe holding member 304 has a small width, the inner pipe holding member 304 does not close the gap 331 as shown in FIG. 2 and core sand does not remain in the gap 331.
[0055]
The tip portion 305 of the inner pipe 302 protrudes outward from the surface of the engine side flange 303, and after the inner pipe 302 and the inner pipe holding member 304 are integrally cast, when the surface of the engine side flange 303 is flattened, Processing is performed so that the end of the pipe 302 and the surface of the flange 303 are the same. As a result, since the tip of the inner pipe 302 is in contact with the gasket 311, it is possible to suppress the exhaust gas in the inner pipe 302 from flowing into the gap 331.
[0056]
Next, the operation of the dual structure exhaust manifold of the above embodiment will be described.
[0057]
First, the temperature rise of the exhaust gas at the time of starting the engine will be described.
[0058]
Except immediately after the engine is stopped, the temperatures of the outer cylinder 301 and the inner pipe 302 of the dual-structure exhaust manifold at the time of starting the engine are the same as the outside air temperature. After the engine is started, in the dual structure exhaust manifold, the inner pipe 302 is first heated by the exhaust gas flowing through the inner pipe 302. As a result, the wall temperature of the inner pipe 302 increases, but the temperature of the exhaust gas decreases by the amount of heat applied to the inner pipe 302.
[0059]
In the dual-structure exhaust manifold of this embodiment, since the thickness of the inner tube 302 is reduced, the heat capacity of the inner tube 302 is small, and the wall temperature of the inner tube 302 rises early. Therefore, the amount of heat transferred from the exhaust gas to the inner pipe 302 is suppressed low, and the temperature of the exhaust gas is suppressed from being reduced. As a result, the temperature of the inlet gas of the catalyst installed behind the dual structure exhaust manifold of the present embodiment is reduced. Can be raised early.
[0060]
At this time, when the exhaust gas leaks into the gap between the inner pipe 302 and the outer pipe 301, as shown in FIG. 8, the temperature of the exhaust gas flowing into the catalyst installed at the rear of the exhaust pipe becomes large immediately after the engine is started. And the exhaust gas purification efficiency is deteriorated. In the exhaust manifold having the double pipe structure according to the present embodiment, the tip of the inner pipe 302 is the same as the flange 303 surface. Since the hole of the gasket 311 attached to the flange 303 is smaller than the inner diameter of the tip of the inner tube 302, the tip of the inner tube 302 contacts the gasket 311, the inner tube 302 and the gap 331 are sealed by the gasket 311, and the exhaust gas is 331 can be prevented from being leaked, and the purification efficiency of the catalyst can be improved.
[0061]
Next, in a state where the exhaust gas and the exhaust manifold are sufficiently warmed, for example, when traveling in an urban area, the inner pipe 302 and the outer pipe 301 may be out of contact with each other due to a difference in the pipe wall temperature between the inner pipe 302 and the outer pipe 301 and a difference in a material constituting the pipe. A difference in thermal expansion occurs between the cylinder 301 and the cylinder 301.
[0062]
That is, since the outer cylinder 301 is not directly exposed to the exhaust gas and is cooled by the traveling wind, the surface temperature becomes lower and the thermal expansion is smaller than that of the inner pipe 302. On the other hand, the inner pipe 302, which is directly exposed to the high-temperature exhaust gas and is insulated by the air layer in the gap 331 between the inner pipe 302 and the outer cylinder 301, has a high temperature, and large thermal expansion occurs.
[0063]
Most of the thermal expansion of the inner tube 302 is absorbed by a thermal expansion absorbing portion 310 which is appropriately formed in the middle of the inner tube 302 and has a convex shape toward the outer cylinder. In the engine side flange 303, the expansion due to the thermal expansion of the inner pipe 302 is absorbed by the thermal expansion absorbing section 310 near the inner pipe holding member 304, so that the stress is alleviated to the inner pipe holding member 304, and the inner pipe holding member 304 can be prevented from being deformed and damaged.
[0064]
Since the position of the inner tube holding member 304 to which the inner tube holding member 304 is fixed by welding is fixed by the inner tube holding member 304, the expansion of the inner tube 302 due to thermal expansion on the engine side from the inner tube holding member 304 is small. It becomes. This slight elongation is absorbed by the expansion of the diameter of the inner tube 302 toward the outer cylinder 301 at the engine-side tip 305 and by the R portion of the inner tube holding member 304. For this reason, the extension of the inner tube 302 is suppressed by the gasket 311 and the engine, so that the distal end portion 305 of the inner tube 302 can be prevented from being damaged.
[0065]
The same structure as the engine-side flange 303 is used for the front tube-side flange structure of the dual-structure exhaust manifold, so that core sand can be efficiently extracted without providing holes for sand removal. Further, it is possible to suppress a decrease in the gas temperature due to the leakage of the exhaust gas to the gap 331, and to prevent the inner tube 302 from being damaged due to thermal expansion and contraction.
[0066]
[Example 2]
FIG. 4 is a sectional view of an engine-side flange portion according to a second embodiment of the present invention. An inner tube holding member 404 is fixedly welded to the inner tube 402, and a thermal expansion absorbing portion 410 swelling convexly toward the outer tube 401 is formed downstream of the inner tube holding member 404. The engine-side tip 406 of the inner tube 402 extends toward the engine without changing the diameter, and the tip 406 is located inside the surface of the engine-side flange 403. The gasket 411 for sealing the exhaust manifold and the engine is formed of a metal such as stainless steel, and the inside is bent toward the exhaust manifold to form a cylindrical portion 412. The inner diameter of the cylindrical portion 412 is formed slightly larger than the outer diameter of the inner tube 402.
[0067]
With the gasket 411 mounted between the engine and the flange 403 of the exhaust manifold, the outer circumference of the inner pipe 402 of the exhaust manifold is inserted into the cylindrical portion 412 of the gasket. At this time, since the gap between the inner tube 402 and the cylindrical portion 412 of the gasket is small, the gasket is in a fitted state. The structure and operation of the inner tube holding member 404 and the thermal expansion absorbing part 410 are the same as those of the first embodiment.
[0068]
In the dual structure exhaust manifold according to the present embodiment, since the inner pipe 402 is closely inserted into the cylindrical portion 412 of the gasket, the exhaust gas flowing in the inner pipe 402 flows to the gap 431 between the inner pipe 402 and the outer pipe 401. Inflow can be largely suppressed. Further, at a high temperature, the expansion of the inner pipe 402 due to thermal expansion on the engine side from the welded fixed portion of the inner pipe 402 to the inner pipe holding member 404 is caused by the fact that the inner pipe 402 and the cylindrical portion 412 of the gasket are not fixed. It is absorbed by moving inside the cylindrical portion 412 of the gasket.
[0069]
[Example 3]
FIG. 5 is a sectional view of an engine-side flange portion according to a third embodiment of the present invention. An inner tube holding member 504 is welded and fixed to the inner tube 502, and a thermal expansion absorbing portion 510 that protrudes toward the outer tube 501 is formed downstream of the inner tube holding member 504. The engine-side tip 505 of the inner pipe is expanded in diameter toward the outer cylinder 501, and the diameter of the tip 505 of the inner pipe is larger than the diameter of the exhaust port of the engine at the tip. The engine-side tip 505 of the inner pipe 502 is located inside the engine-side flange 503 of the exhaust manifold. The gasket 511 for sealing the exhaust manifold and the engine is formed of a metal such as stainless steel having oxidation resistance and high temperature resistance. The inside is bent toward the exhaust manifold side to form a cylindrical portion 512. The diameter of the cylindrical portion 512 is slightly reduced from the disk-shaped surface of the gasket 511 toward the distal end, and the outer diameter of the cylindrical portion 512 is formed slightly smaller than the inner diameter of the distal end portion 505 of the inner tube 502. ing.
[0070]
With the gasket 511 mounted between the engine and the flange 503 of the exhaust manifold, the cylindrical portion 512 of the gasket 511 is inserted into the inner pipe 502 of the exhaust manifold. At this time, the distal end portion 505 of the inner tube 502 has a diameter increasing toward the distal end, while the distal end of the cylindrical portion 512 of the gasket 511 has a reduced diameter, so that it is in a fitted state. The structure and operation of the inner tube holding member 504 and the thermal expansion absorbing part 510 are the same as those of the first embodiment.
In the dual-structure exhaust manifold according to the present embodiment, since the cylindrical portion 512 of the gasket is closely inserted into the inner tube 502, the exhaust gas flowing through the inner tube 502 flows to the gap 531 between the inner tube 502 and the outer tube 501. Inflow can be further suppressed as compared with the above embodiment. At a high temperature, the expansion of the inner tube 502 due to thermal expansion on the engine side from the welded fixed portion with the inner tube holding member 504 is caused by the fact that the inner tube 502 and the cylindrical portion 512 of the gasket 511 are not fixed. Is absorbed by moving around the outer periphery of the cylindrical portion 512 of the gasket.
[0071]
[Example 4]
FIG. 6 is a sectional view of an engine-side flange portion according to a fourth embodiment of the present invention. An inner tube holding member 604 is welded and fixed to the inner tube 602, and a thermal expansion absorbing portion 610 that protrudes toward the outer tube 601 is formed downstream of the inner tube holding member 604. The engine-side tip 606 of the inner tube 602 extends toward the engine without changing the diameter, and the tip 606 is located outside the engine-side flange 603 surface.
[0072]
A first gasket 611 for sealing exhaust gas, a support member 614, and a second gasket 613 are mounted between the engine and the exhaust manifold. The first gasket is formed so that the diameter of the hole is slightly larger than the outer diameter of the inner pipe 602, and is in close contact with the engine-side flange 603 of the exhaust manifold so as to hold the inner pipe 602. Further, the first gasket 611 is formed of a material having high temperature resistance and oxidation resistance because a part of the first gasket 611 is exposed to high temperature exhaust gas. The second gasket is larger than the inner diameter of the inner pipe 602 and the exhaust port of the engine, and is in close contact with the engine. The support member 614 has a hole larger than the outer diameter of the inner tube 602 and is inserted between the first gasket 611 and the second gasket 613 so that the distal end 606 of the inner tube 602 is located in the support member 614. I do. The structure and operation of the inner tube holding member 604 and the thermal expansion absorbing part 610 are the same as those in the first embodiment.
[0073]
In the dual structure exhaust manifold according to the present embodiment, since the inner pipe 602 is tightly inserted into the first gasket 611, the exhaust gas flowing through the inner pipe 602 flows to the gap 631 between the inner pipe 602 and the outer cylinder 601. Inflow can be suppressed. Further, a portion protruding from the flange 603 surface of the inner tube 602 for holding the inner tube 602 with the first gasket 611 and a portion fixed by welding to the inner tube holding member 604 of the inner tube 602 at a high temperature. Elongation due to thermal expansion on the engine side is absorbed in the support member 614 having a hole diameter larger than the outer diameter of the inner pipe 602. At this time, since the expansion of the entire inner tube 602 is absorbed by the thermal expansion absorbing portion 610 formed in the middle of the inner tube 602 as in the first embodiment, the expansion of the inner tube 602 in the support member 614 is performed. Is small, so that the tip 606 of the inner tube 602 does not hit the engine and is damaged.
[0074]
[Example 5]
FIG. 7 is a sectional view of an engine-side flange portion according to a fifth embodiment of the present invention. The structure other than the support 714 inserted between the first gasket 711 and the second gasket 713 and the inner tube 702 is the same as that of the fourth embodiment. The inner pipe 702 has an inner diameter larger than the inner diameter of the exhaust port of the engine on the engine side from the thermal expansion absorbing section 710. The other structure is the same as that of the fourth embodiment. The support member 714 is formed such that the inside diameter of the hole is equal to the exhaust port of the engine and smaller than the inside diameter of the distal end 706 of the inner pipe 702 of the exhaust manifold. On the exhaust manifold side of the support member 714, a U-shaped groove 715 is formed over the entire circumference. With the exhaust manifold attached to the engine, the distal end 706 of the inner pipe 702 is inserted into the U-shaped groove 715 of the support member 714.
[0075]
In the dual structure exhaust manifold according to the present embodiment, since the exhaust gas can be prevented from directly hitting the first gasket 711 and the first gasket 711 can be prevented from being deteriorated, the first gasket 711 can be made resistant to oxidation or high temperature. There is no need to use a material of any nature. Other effects are the same as those of the fourth embodiment.
[0076]
The effect of increasing the inner diameter of the inner tube 702 is the same even if the portion other than the thermal expansion absorbing portion 710 is used, and the effect is obtained even if the distal end 706 of the inner tube 702 increases in diameter toward the outer tube 701. Is the same.
[0077]
[Example 6]
In the first embodiment, the gasket 311 for sealing the exhaust gas is made of a metal such as stainless steel having oxidation resistance and high temperature resistance.
[0078]
In the present embodiment, the elongation of the distal end 305 of the inner tube 302 is suppressed by the metal gasket 311, so that the occurrence of scratches on the engine side by the inner tube 302 can be suppressed.
[0079]
[Example 7]
In the first embodiment, a plurality of thermal expansion absorbing portions 310 of the inner pipe 302 are provided downstream of a portion where the inner pipe holding member 304 is welded.
[0080]
In the present embodiment, the stress applied to the inner tube holding member 304 can be reduced, and the inner tube holding member 304 can have low responsiveness.
[0081]
Example 8
In the first embodiment, the welding of the inner pipe holding member 304 to the inner pipe 302 is performed by spot welding.
[0082]
In the present embodiment, the welding of the inner tube holding member 304 to the inner tube 302 becomes easier, and the contact portion with the inner tube 302 is reduced, so that the amount of heat escaping from the inner tube 302 to the outer tube 301 is reduced. This suppresses a decrease in the wall temperature of the pipe 302, which leads to an early rise in the exhaust gas temperature.
[0083]
[Example 9]
FIG. 12 is a sectional view of an engine-side flange portion according to a ninth embodiment of the present invention, showing a state before being attached to the engine, and FIG. 13 shows a state attached to the engine.
[0084]
An inner tube holding member 1204 is fixed to the inner tube 1202 by welding, and a thermal expansion absorbing portion 1210 which protrudes toward the outer tube 1201 is formed downstream of the inner tube holding member 1204. The engine-side tip of the inner pipe 1202 extends toward the engine without changing the diameter, and the tip of the inner pipe 1202 is located inside the surface of the engine-side flange 1203. A ring support 1232 made of a metal material such as stainless steel is cast in the engine side flange portion 1203 of the exhaust manifold. The flange 1203 side of the exhaust manifold of the ring support 1232 is machined on the same plane as the flange 1203 or is located inside the flange 1203, and the engine-side tip of the inner pipe 1202 is located near the center in the length direction of the ring support 1232. Has a length such that it is located at Further, the inner surface of the ring support 1232 is smoothened so as to reduce the diameter from the flange surface 1203 of the exhaust manifold toward the inside. The outer diameter of the core of the ring gasket 1233 is larger than the gap between the outer diameter of the cylindrical portion at the tip of the inner pipe 1202 on the engine side and the smallest inner diameter of the ring support 1232.
[0085]
In a state where the exhaust manifold 1201 is attached to the engine, the ring gasket 1233 is densely attached to the outer periphery of the cylindrical portion at the engine-side end of the inner pipe 1202, the smoothly processed inner surface of the ring support 1232, and the flange surface of the engine. Because of the contact, the gap 1231 between the inner tube 1202 and the outer tube 1201 and the inside of the inner tube 1202 are sealed on the engine side of the exhaust manifold. The structure and operation of the inner tube holding member 1204 and the thermal expansion absorbing portion 1210 are the same as those in the first embodiment.
[0086]
In the dual structure exhaust manifold according to the present embodiment, since a large gap is formed between the ring support 1232 and the inner pipe 1202, the core sand after casting is easy to remove, and the core sand remains in the gap. Absent.
[0087]
On the engine side of the exhaust manifold, the distal end of the inner pipe 1202 and the outer cylinder 1201 are sealed by a ring gasket 1233 via a ring support 1232, so that exhaust gas flowing through the inner pipe 1202 leaks to the gap 1231. Can be prevented, and the purification efficiency of the catalyst is improved. Furthermore, since the flange 1203 of the exhaust manifold and the flange portion of the engine are similarly sealed by the ring gasket 1233 via the ring support 1232, the exhaust gas does not leak to the outside air. Also, at a high temperature, the expansion of the inner tube 1202 due to thermal expansion on the engine side from the welded fixed portion of the inner tube 1202 to the inner tube holding member 1204 is because the inner tube 1202 and the ring gasket 1233 are not fixed. It is absorbed by moving inside 1233.
[0088]
The same operation can be achieved even if a plate-shaped gasket is attached to the flange 1203 of the exhaust manifold and the flange surface of the engine.
[0089]
[Example 10]
FIG. 14 is a sectional view of an engine-side flange portion according to a tenth embodiment of the present invention. The engine-side tip of the inner tube 1402 extends toward the engine without changing the diameter, and the tip of the inner tube 1402 has a thermal expansion absorbing portion 1410 that protrudes toward the outer tube 1401. Is formed, and its tip is located inside the surface of the engine side flange 1403.
[0090]
On the inner pipe 1402 side of the flange 1403 portion of the exhaust manifold, a flange smooth cut portion 1434 is formed into a flat surface from the engine-side smooth surface to the inside of the exhaust manifold so that the inner diameter decreases. The outer diameter of the core of the ring gasket 1433 is larger than the gap between the outer diameter of the cylindrical portion at the engine-side tip of the inner pipe 1402 and the smallest inner diameter of the flange smooth cut portion 1434.
[0091]
In a state where the exhaust manifold 1401 is attached to the engine, the ring gasket 1433 forms an R-shape of a thermal expansion absorbing portion 1410 formed on the outer periphery of the cylindrical portion at the engine-side end of the inner tube 1402 and the engine-side end of the inner tube 1402. Of the exhaust manifold and the flat surface of the flange smooth cut portion 1434 of the exhaust manifold and the flange surface of the engine, so that the gap 1431 between the inner pipe 1402 and the outer cylinder 1401 and the inside of the inner pipe 1402 are Sealed on the engine side.
[0092]
In the dual structure exhaust manifold according to the present embodiment, the space between the outer tube 1401 and the inner tube 1402 is narrowed, but the gap is formed, so that the core sand after casting does not become difficult to remove, and There is no core sand left in the gap.
[0093]
On the engine side of the exhaust manifold, the distal end of the inner pipe 1402, the thermal expansion absorbing portion 1410 near the distal end, and the outer cylinder 1401 are sealed by a ring gasket 1433, so that exhaust gas flowing through the inner pipe 1402 is Therefore, it is possible to prevent the gas from leaking into the gap 1431, thereby improving the purification efficiency of the catalyst. The prevention of exhaust gas leakage from the exhaust manifold 1401 and the flange surface of the engine is the same as in the ninth embodiment. Further, the thermal expansion of the inner pipe 1402 at a high temperature is absorbed by the thermal expansion absorbing portion 1410 formed at the tip of the inner pipe 1402 on the engine side.
[0094]
[Example 11]
FIG. 15 is a sectional view of an engine-side flange portion according to Embodiment 11 of the present invention. The engine-side tip of the inner tube 1502 extends toward the engine without changing the diameter, and the tip is located inside the engine-side flange 1503 surface. With the exhaust manifold attached to the engine, a plate-like gasket 1511 is mounted between the flange 1503 surface of the exhaust manifold and the flange surface of the engine. The structure other than the distal end portion of the inner tube 1502 and the plate-like gasket is the same as that of the tenth embodiment.
[0095]
In the dual structure exhaust manifold according to the present embodiment, since the outer diameter of the core of the ring gasket 1533 increases, the pressure of the exhaust gas increases at high temperatures, and the exhaust gas may escape from the ring gasket 1533 to the outside air. This can be prevented by the plate-like gasket 1511. At high temperatures, there is no problem if the exhaust gas leaks into the gap 1531 between the inner tube 1502 and the outer tube 1501.
[0096]
[Example 12]
FIG. 16 is a sectional view of an engine-side flange portion according to a twelfth embodiment of the present invention. The distal end of the inner tube 1602 includes a diameter reducing portion 1635 that reduces the diameter toward the engine side. The structure other than the diameter reducing portion 1635 of the inner tube 1602 is the same as that of the ninth embodiment.
[0097]
In the dual structure exhaust manifold according to the present embodiment, since the diameter reducing portion 1635 is formed at the engine-side tip of the inner pipe 1602, the ring gasket 1633 can be easily attached.
[0098]
Embodiment 13 FIGS. 17 and 18 are a sectional view of an engine-side flange portion and a front tube-side sectional view of Embodiment 13 of the present invention. This embodiment has a structure in which the inner pipe holding member for fixing the inner pipe 1702 to the outer cylinder 1701 in the tenth embodiment on the engine side of the exhaust manifold is eliminated. On the front tube 1843 side of the exhaust manifold, the front tube 1843 end of the inner tube 1802 is located closer to the front tube 1843 than the front tube side flange 1844 of the exhaust manifold without changing the diameter. In the front tube side flange 1844 portion of the exhaust manifold 1801, a flange smooth cut portion 1834 is flattened so that the inside diameter becomes smaller from the front tube side smooth surface of the flange 1844 toward the inside of the exhaust manifold. The front tube 1843 has an inner diameter larger than the outer diameter of the inner pipe 1802 of the exhaust manifold.As front tube side gasketMetal ring gasket1833Has a core outer diameter larger than the gap between the smallest inner diameter of the flange smooth cut portion 1834 and the outer diameter of the inner pipe 1802 of the exhaust manifold. With the front tube 1843 attached to the exhaust manifold 1801, the ring gasket 1833 is tightly mounted on the outer periphery of the inner tube 1802 of the exhaust manifold, the flange smooth cut portion 1834, and the flange 1842 surface of the front tube 1843.
[0099]
In the dual structure exhaust manifold according to the present embodiment, the inner pipes 1702 and 1802 of the exhaust manifold areEngine side gasketRing gasket 1733And a ring gasketSince it is positioned and held by 1833, an inner tube holding member for positioning and holding the inner tubes 1702 and 1802 is not required.
[0100]
[Example 14]
FIG. 19 is a sectional view of an engine-side flange portion according to Embodiment 14 of the present invention. The engine-side tip 1906 of the inner tube 1902 extends toward the engine without changing its diameter, and the tip 1906 is located outside the engine-side flange 1903 surface.
[0101]
A support member 1914 and a plate-like gasket 1913 are mounted between the engine and the exhaust manifold. The support member 1914 has a hole larger than the outer diameter of the inner tube 1902, and is inserted between the flange 1903 of the exhaust manifold and the plate-like gasket 1913. The tip 1906 of the inner tube 1902 is located in the support member 1914. . On the inner pipe 1902 side of the flange portion 1903 of the exhaust manifold, a flange smooth cut portion 1934 is machined in a plane from the engine-side smooth surface to the inside of the exhaust manifold so that the inner diameter decreases. The outer diameter of the core of the ring gasket 1933 is larger than the gap between the outer diameter of the cylindrical portion at the engine-side end of the inner tube 1902 and the inner diameter of the flange smooth cut portion 1934 having the smallest diameter.
[0102]
When the exhaust manifold 1901 is attached to the engine, the distal end portion 1906 of the inner pipe of the exhaust manifold and the support member 1914 do not adhere to each other. In order to make close contact with the plane of the flange smooth cut portion 1934 of the exhaust manifold and the flat surface of the support member on the exhaust manifold side, the gap 1931 between the inner tube 1902 and the outer tube 1901 and the inside of the inner tube 1902 are connected to the engine of the exhaust manifold. Sealed on the side.
[0103]
In the dual structure exhaust manifold according to the present embodiment, the expansion due to the thermal expansion of the inner pipe 1902 at the engine side from the welding fixed portion with the inner pipe holding member 1904 at a high temperature has a hole diameter larger than the outer diameter of the inner pipe 1902. It is absorbed in the support member 1914.
[0104]
【The invention's effect】
As described above, according to the first aspect of the present invention, the core for forming the gap between the inner tube and the outer tube used when casting the inner tube and the inner tube holding member is defined as the inner tube. Since it can be pulled out from the communicating part with the gap between the outer cylinders, it is not necessary to provide a sand hole for extracting core sand, workability is improved, and the core is inserted between the inner pipe and the outer cylinder. Can be prevented from remaining.
[0105]
Further, since the thickness of the inner tube can be reduced, the heat capacity of the inner tube is small, and the wall temperature of the inner tube rises early. Therefore, the amount of heat transfer from the exhaust gas to the inner pipe is suppressed low, and the temperature of the exhaust gas is suppressed from decreasing. As a result, the temperature of the inlet gas of the catalyst installed behind the exhaust manifold can be increased.
[0106]
In addition, since the gap between the inner tube and the outer cylinder is closed by the gasket, it is possible to prevent the exhaust gas from flowing into the gap between the inner tube and the outer cylinder, and it is possible to suppress a decrease in the exhaust gas temperature.
[0107]
When the temperature is high, the position of the inner pipe on the engine side is fixed by the inner pipe holding member, and the diameter of the inner pipe is expanded toward the outer cylinder. By absorbing in the direction, the tip can be prevented from being damaged, and furthermore, the thermal expansion absorbing structure provided on the downstream side of the inner tube holding member absorbs the expansion caused by the thermal expansion of the inner tube downstream of the inner tube holding member, Prevents damage to the inner tube.
[0108]
According to the second aspect of the present invention, since the cylindrical portion of the metal gasket is attached to the outer periphery of the inner tube, it is possible to prevent the exhaust gas from flowing into the gap between the inner tube and the outer tube, and to reduce the temperature of the exhaust gas. Can be suppressed.
[0109]
Further, at high temperatures, the expansion due to thermal expansion of the inner pipe on the engine side from the inner pipe holding member welded and fixed to the inner pipe is absorbed by the cylindrical portion of the metal gasket, so that damage to the inner pipe can be prevented.
[0110]
According to the third aspect of the present invention, since the cylindrical portion of the metal gasket is mounted inside the inner tube, it is possible to prevent the exhaust gas from flowing into the gap between the inner tube and the outer tube, thereby reducing the temperature of the exhaust gas. Can be suppressed.
[0111]
In addition, at high temperatures, the expansion due to thermal expansion of the inner pipe on the engine side from the inner pipe holding member welded and fixed to the inner pipe is absorbed by the diameter expansion portion of the inner pipe and the cylindrical portion of the metal gasket. Pipe breakage can be prevented.
[0112]
According to the invention of claim 4, it is possible to prevent the exhaust gas from leaking into the gap between the inner pipe and the outer cylinder with the first gasket without expanding the engine-side tip of the inner pipe and bending the gasket. Suppress lowering of exhaust gas temperature. In addition, the support member can absorb the elongation of the inner tube at high temperature and prevent the inner tube from being damaged.
[0113]
According to the invention of claim 5, deterioration of the gasket caused by exhaust gas coming into contact with the first gasket for preventing leakage of exhaust gas into the gap between the inner pipe and the outer cylinder for a long time can be suppressed.
[0114]
According to the sixth aspect of the present invention, the elongation of the tip of the inner tube is suppressed by the metal gasket, so that the occurrence of scratches on the engine side due to the inner tube can be suppressed.
[0115]
According to the invention of claim 7, it is possible to prevent the deterioration of the inner tube holding member due to the expansion of the thermal expansion of the inner tube at a high temperature.
[0116]
According to the invention of claim 8, the inner tube holding member can be easily fixed by welding, the heat capacity of the member directly in contact with the inner tube can be reduced, and the rise of the exhaust gas temperature can be accelerated.
[0117]
According to the invention of claim 9, in order to seal the gap between the outer cylinder and the inner pipe of the exhaust manifold and the flange surface of the outer cylinder and the engine with the ring gasket, the exhaust gas is escaping to the outside of the exhaust manifold, Flow into the gap between the inner tube and the outer tube can be prevented, and the positioning of the inner tube becomes easier when the exhaust manifold is attached to the engine.
[0118]
Further, by using a ring support separate from the exhaust manifold body, the diameter of the ring gasket can be reduced. Further, since the inner diameter of the ring support is sufficiently larger than the outer diameter of the inner tube, sand removal after casting is easy.
[0119]
According to the tenth aspect of the present invention, since the R portion of the thermal expansion absorbing structure of the inner pipe and the smooth cut portion of the flange of the exhaust manifold are sealed with the ring gasket, a separate ring support is not required.
[0120]
According to the invention of claim 11, in order to seal the tip of the cylindrical inner tube and the smooth cut portion of the flange of the exhaust manifold with a large-diameter ring gasket, a separate ring support or the tip of the inner tube is used. No thermal expansion absorbing structure is required.
[0121]
According to the twelfth aspect of the present invention, the diameter of the tip of the inner tube is reduced toward the engine, and the ring support separate from the exhaust manifold reduces the inner diameter toward the inside of the exhaust manifold. Therefore, mounting of the ring gasket becomes easy.
[0122]
According to the thirteenth aspect, on the front tube side of the exhaust manifold, the gap between the inner tube and the outer tube and the space between the outer tube and the front tube are formed.Front tube sideSince the gasket is used for sealing, the positioning and holding of the inner tube are facilitated, and the holding member for the inner tube is not required at the engine-side flange portion.In addition, the engine-side gasket prevents the exhaust gas from leaking into the gap between the inner tube and the outer cylinder without processing the expansion or contraction of the engine-side tip of the inner tube, and suppresses a decrease in the exhaust gas temperature.
[Brief description of the drawings]
FIG. 1 is a schematic structural view of an exhaust manifold of an automobile to which the present invention is applied.
FIG. 2 is a cross-sectional view showing an exhaust manifold according to an embodiment of the present invention before machining a flange surface.
FIG. 3 is a view showing a state where the engine is mounted on the engine according to the embodiment of the present invention.
FIG. 4 is a view showing a state where the engine is mounted on the engine according to the second embodiment of the present invention.
FIG. 5 is a diagram illustrating a state where the engine is mounted on the engine according to the third embodiment of the present invention.
FIG. 6 is a view showing a state where the engine is mounted on an engine according to a fourth embodiment of the present invention.
FIG. 7 is a diagram showing a state where the engine is mounted on an engine according to a fifth embodiment of the present invention.
FIG. 8 is a diagram showing a change in temperature of exhaust gas flowing into a catalyst according to the present invention.
FIG. 9 is a longitudinal sectional view of a conventional example.
FIG. 10 is a longitudinal sectional view of a conventional example.
FIG. 11 is a longitudinal sectional view of a conventional example.
FIG. 12 is a diagram showing a state before mounting on an engine according to the ninth embodiment of the present invention.
FIG. 13 is a view showing a state where the engine is mounted on the engine according to the ninth embodiment of the present invention.
FIG. 14 is a diagram showing a state where the engine is mounted on the engine according to the tenth embodiment of the present invention.
FIG. 15 is a diagram illustrating a state where the engine is mounted on the engine according to the eleventh embodiment of the present invention.
FIG. 16 is a view showing a state where the engine is mounted on the engine according to the twelfth embodiment of the present invention.
FIG. 17 is a diagram illustrating a state where the engine is mounted on an engine according to a thirteenth embodiment of the present invention.
FIG. 18 is a diagram illustrating a state where the electronic device is mounted on a front tube according to a thirteenth embodiment of the present invention.
FIG. 19 is a diagram illustrating a state where the engine is mounted on an engine according to a fourteenth embodiment of the present invention.
[Explanation of symbols]
301, 401, 501, 601, 701, 1201 outer cylinder
302, 402, 502, 602, 702, 1202 Inner tube
303, 403, 503, 603, 703, 1203 Flange
304, 404, 504, 604, 704, 1204 Inner tube holding member
310, 410, 510, 610, 710, 1210 Thermal expansion absorbing structure
311,411,511 Gasket
613,713 Second gasket
614,714,1914 Support
331,431,531,631,731,1231 Gap between inner tube and outer tube
1232 Ring Support
1233, 1833 Ring gasket
1434, 1834 Flange smooth cut section
1635 Inner tube diameter reduction section
1843 Front tube

Claims (13)

One end of a band-shaped plate material is formed at the engine-side flange portion of the inner pipe in an engine dual-structure exhaust manifold in which an inner pipe formed thinly of a stainless steel material is made of cast iron and the inside of the inner pipe is a passage for exhaust gas. Is welded and fixed to the outer tube side of the inner tube, the other end of the plate material extends toward the outer tube in an R shape from the inner tube, and the tip of the plate material is fixed to a plurality of inner tube tubes which are cast and fixed to the outer tube. The member and the engine-side end of the inner pipe have a diameter that is expanded toward the outer cylinder, and the expanded portion of the inner pipe has a diameter that is larger than the inner diameter of the exhaust port of the engine at the end surface of the flange portion. And the engine-side flange of the exhaust manifold are formed on the same surface with the end of the engine-side diameter expansion of the inner pipe, and the inner pipe holding the inner pipe welded and fixed to the inner pipe. On the downstream side of the member, A heat expansion absorbing structure of the inner tube in which a part of the inner tube expands in a convex shape toward the cylinder side, and a gasket for sealing exhaust gas between an engine head and the exhaust manifold, A double structure exhaust manifold having a gasket having a hole smaller than the inner diameter of the inner tube. 2. The exhaust manifold according to claim 1, wherein an end of the inner pipe on the engine side includes:
An inner pipe located inside the engine-side flange surface of the exhaust manifold without expanding the inner diameter, and the gasket is formed of metal such as stainless steel, and has a cylindrical portion bent toward the exhaust manifold side inside the gasket. A dual structure exhaust manifold, characterized in that the cylindrical portion has a gasket mounted on the outer periphery of the inner pipe while being mounted between the exhaust manifold and an engine. 2. The exhaust manifold according to claim 1, wherein an end of the inner pipe on the engine side includes:
The diameter increases toward the engine side, and the tip of the inner pipe is formed of a metal such as stainless steel as the inner pipe located inside the engine-side flange surface, and the gasket is formed of metal such as stainless steel, and the inside of the gasket is formed on the exhaust manifold side. It has a bent cylindrical part, the diameter of which decreases toward the inside of the exhaust manifold, and is mounted inside the expanded diameter part of the inner pipe in a state of being mounted between the exhaust manifold and the engine. A dual structure exhaust manifold that has a gasket. 2. The exhaust manifold according to claim 1, wherein an end of the inner pipe on the engine side includes:
Without expanding the inner diameter, between the inner pipe located on the engine side from the engine side flange surface of the exhaust manifold, and between the exhaust manifold flange and the engine, exhaust gas that is in close contact with the outer circumference of the inner pipe and the exhaust manifold flange is removed. A first gasket to be sealed, a second gasket having a hole larger than the inside diameter of the exhaust port of the engine and closely attached to the engine, and an outer diameter of the inner pipe between the first gasket and the second gasket. A dual structure exhaust manifold having a larger hole, the tip of the inner tube having a support having a thickness located in the hole of the support. 5. The dual structure exhaust manifold according to claim 4, wherein the support member has a hole smaller than the inner pipe, and a U-shaped groove is formed on the exhaust manifold side over the entire circumference, and the U-shaped exhaust manifold is formed. A dual-structure exhaust manifold, wherein an engine-side tip portion of the inner pipe is inserted into the groove. 2. The dual structure exhaust manifold according to claim 1, wherein the gasket is formed of a metal such as stainless steel. 2. The exhaust manifold according to claim 1, wherein a part of the inner pipe is located downstream of the inner pipe holding member welded and fixed to the inner pipe, toward the outer cylinder. Characterized by having a plurality of thermal expansion absorbing structures of an inner tube which bulges into an R-shaped convex shape. The dual structure exhaust manifold according to claim 1, wherein the inner pipe holding member is fixed to an outer periphery of the inner pipe by spot welding. The exhaust manifold according to claim 2, wherein the engine-side flange portion of the exhaust manifold is formed in a cylindrical shape with a metal material such as stainless steel, and the outer periphery is cast when the exhaust manifold is cast. The inner diameter is narrowed down from the flange surface toward the inside of the exhaust manifold, where the diameter is the smallest, larger than the inner pipe of the dual structure exhaust manifold, and having a length from the engine-side tip of the inner pipe to the inner side, The inner surface is machined smoothly, and the engine side surface is machined to the same surface as the flange surface of the exhaust manifold, or a ring support cast inside the exhaust manifold, and the most of the ring support. Larger than the gap between the small inner diameter and the outer diameter of the inner tube A ring gasket made of a metal having an outer diameter of, and in a state where the exhaust manifold is attached to an engine, the ring gasket is disposed between an outer periphery of the inner pipe, an inner surface of the ring support, and a flange surface of the engine. Dual structure exhaust manifold characterized by tight mounting. 3. The dual structure exhaust manifold according to claim 2, wherein a part of the inner pipe, which is formed at an engine-side tip of the inner pipe, bulges in a part of the inner pipe toward the outer cylinder in a convex shape of an R shape. In the thermal expansion absorbing structure of the pipe and the engine side flange portion of the exhaust manifold,
From the engine-side smooth surface of the flange toward the inside of the exhaust manifold, a flange smooth-cut portion having a flat inner surface with a reduced inner diameter, and a gap between the smallest inner diameter of the flange smooth-cut portion and the outer diameter of the inner pipe. It is made of a metal ring gasket having a larger core outer diameter, and in a state where the exhaust manifold is attached to the engine, the ring gasket is used to prevent the outer circumference of the engine-side tip of the inner pipe or the heat of the inner pipe. A dual structure exhaust manifold, which is closely mounted between an outer periphery of a convex portion of an expansion absorbing structure, the flange smooth cut portion, and a flange surface of an engine. The dual-structure exhaust manifold according to claim 10, wherein an inner pipe on an engine side of an inner pipe holding member welded and fixed to the inner pipe,
The inner pipe located inside the exhaust manifold from the engine side flange surface of the exhaust manifold without providing a thermal expansion absorbing structure, and the ring gasket is attached to the engine with the exhaust manifold attached to the engine, and the end side of the inner pipe at the engine side. Characterized in that the exhaust manifold is closely mounted between the outer periphery of the engine, the flange smooth cut portion, and the flange surface of the engine. 10. The exhaust manifold according to claim 9, wherein at a tip of the inner pipe on the engine side, a tip of the inner pipe for reducing the diameter of the inner pipe toward the engine, and an inner surface. Is formed of a ring support whose inner diameter is narrowed from the flange surface toward the inside of the exhaust manifold, and in a state where the exhaust manifold is attached to the engine, the ring gasket has an outer periphery of a reduced diameter end portion of the inner pipe; A dual-structure exhaust manifold that is closely mounted between the inner surface of the ring support and the flange surface of the engine. In an engine dual structure exhaust manifold having an inner tube formed of a thin stainless steel material and an outer tube made of cast iron surrounding the outer periphery of the inner tube, and having the inner tube as an exhaust gas passage,
A part of the engine-side tip of the inner pipe is expanded to the outer cylinder side in an R-shaped convex shape to form a thermal expansion absorbing structure of the inner pipe,
An engine side gasket for sealing exhaust gas between the engine head and the exhaust manifold, and a front tube side gasket for sealing exhaust gas between the exhaust manifold and the front tube are formed of metal such as stainless steel. ,
Further, the engine-side gasket and the front tube-side gasket are formed to have inner diameters smaller than the inner diameter of the thermal expansion absorbing structure and are mounted on the outer circumference of the inner pipe,
The outer diameter of the outer cylinder on the engine side is formed larger than the exhaust port of the engine, Form the outer diameter of the tube side larger than the diameter of the front tube,
Provide a flange smooth cut portion that is flat-worked so that the inner diameter gradually decreases on the engine side flange and the exhaust manifold side flange of the outer cylinder,
With the engine and the front tube attached to the exhaust manifold, the engine-side gasket and the front-tube-side gasket form the outer periphery of the inner tube, the flange smooth cut portion, the engine flange surface or the front tube flange surface. A dual structure exhaust manifold characterized in that it is configured to be in close contact with each other.

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