JPS6299612A - Exhaust manifold for internal-combustion engine - Google Patents

Abstract

PURPOSE:To ensure the concentricity between a cast iron section and a metal pipe in an cast iron exhaust manifold, by disposing a heat-resistant metal pipes in each inner wall section of the manifold through the intermediary of a heat insulating layer and by casting an end flange of the metal pipe at one end of a manifold pipe. CONSTITUTION:A heat-resistant metal pipe 3 is disposed in each inner wall part of a cast iron section 7 of an exhaust manifold 10 through the intermediary of a heat-insulating material 4. Further, an end flange 3a of the metal pipe 3 is cast at a flange 6a at one end of a manifold pipe 6, and the heat-insulating material is opened to the outside at one end of each branch pipe 2. With this arrangement the heat-insulating material 4 deforms to serve as a buffer material for the solidification and contraction of the cast iron section after casting, and therefore, a variation in pitch of the metal pipe is prevented, and further, it is possible to prevent the cast iron section from making into direct contact with the metal pipe.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an exhaust manifold for an internal combustion engine.

[Conventional technology] The combustion chamber is insulated by lining the inner wall of the cylinder, the lower surface of the cylinder head, and the crown of the piston with a ceramic material that has heat insulation and heat resistance, thereby increasing the thermal efficiency of the lift. Many adiabatic engines have already been proposed in which high-temperature exhaust gas is introduced into turbocharging to recover more heat energy.

And regarding the exhaust manifold of this type of engine,
For example, as disclosed in Japanese Unexamined Patent Publication No. 54-46130, a conventional cast iron exhaust manifold has been proposed in which a heat insulating air layer is provided inside the exhaust manifold and a metal tube is cast inside to achieve heat insulation. In this prior art, the outside of a pre-formed heat-resistant metal tube is filled with &1tvIJ sand, and molten metal is poured onto the outside to form an insulating air layer between the metal tube and the cast iron part.

In this way, when the space between the metal pipe and the vI joint is filled with foundry sand, as shown in FIG. 2b is cast with the metal pipe 3, as shown by the chain lines in FIGS. The metal pipe 3 is deformed together with the molding sand, the center of the branch pipe 2 is deformed, and the dimensions of the cylinder head and the exhaust boat no longer match. That is, in FIG. 2, the length of the exhaust manifold 10 after casting tends to shrink, and the mutual pitch p of the branch pipes 2 tends to become smaller. Such deformation of the cast iron part 7 can be avoided by considering the shrinkage amount in advance and considering the dimensions of the mold, but since the metal pipe 3 deforms and dries in the same way as the cast iron part 7,
, an eccentric lie occurs between the metal tube 3 shown by the solid line in (b) and the cast iron part 7 shown by the chain line.

In addition, the deformation of the metal tube 3 due to the solidification shrinkage force of the cast iron after casting becomes more significant as the exhaust manifold length L becomes longer.If the metal tube 3 comes into direct contact with the cast iron part 7, the insulation effect will be impaired, and the exhaust heat will be transferred to the metal. It is radiated to the outside from the pipe 3 through the cast iron part 7, reducing the exhaust temperature.

[Problems to be Solved by the Invention] In view of the above-mentioned problems, the present invention provides a method in which the metal tube is not deformed due to solidification shrinkage of the cast iron part, and the concentricity between the cast iron part and the metal pipe after casting is not lost. An object of the present invention is to provide an exhaust manifold for an internal combustion engine in which a substantially uniform heat insulating layer is secured between the two.

[Means for solving the problem] In order to achieve the above object, the configuration of the present invention is such that a heat-resistant metal pipe is disposed on the inner wall of the cast iJM exhaust manifold via a heat insulating layer, and the end of the collecting pipe is The end flange of the metal pipe is cast into the branch pipe, and the heat insulating layer is opened to the outside at the end of the branch pipe.

[Function] At the end of the collecting pipe 6, the 7 langes 3a of the metal pipe 3 are fixed by casting around the 7 langes 6a of the cast iron part 7, while at the end of the branch pipe 2, a heat insulating air layer is formed on the outer circumferential side of the metal pipe 3. The metal pipe 3 and the cast iron part 7 are cast in a separated state by combining a heat insulating material 4 corresponding to 4a, such as a heat insulating material 4 made by wrapping ceramic fibers or intertwining ceramic yr1m fibers in a complicated manner. , the heat insulating material 4 is only deformed by the solidification shrinkage of the cast iron part 7, and the metal pipe 3 maintains its original state, so that the mutual pitch between the branch pipes is not changed; in other words, the metal pipe 3 and the cast iron portion 7 of the branch pipe 2 is maintained.

[Examples of the Invention] The present invention will be described based on Examples. As shown in FIG. 2, the exhaust manifold 10 is provided with a large number of branch pipes 2 at one end, and a collecting pipe 6 having a flange 6a at the other end. Then, a heat insulating material 4 is installed inside the metal pipe 3.
is retained. As shown in Fig. 4, this heat insulating material 4 can be made by wrapping ceramic fibers around the outside of a heat-resistant metal tube 3 such as stainless steel, or by using ceramic fibers. ! The roughly entangled material is placed inside a mold so as to surround the metal tube 3, and poured onto the outside of the heat insulating material 4 to form the cast iron part 7.

As shown in FIG. 3, in the present invention, a flange 3a is formed on the metal tube 3 at the end of the collecting pipe 6.
Gather? ! 6, while the end of the branch pipe 2 is formed with a heat insulating material 4 interposed on the outside of the metal pipe 3 so as not to contact the cast iron part 7, as shown in FIG. . That is, the heat insulating material 4 between the metal pipe 3 and the branch pipe 2 is open to the outside.

Note that a flange 2a for coupling to the cylinder head is provided at the end of the branch pipe 2. Metal tube 3 is a long thin metal tube
The pipe may be bent to form a branch pipe 2 at both ends, and other branch pipes 2 and a collecting pipe 6 may be joined in the middle by welding.
These may be overlapped and welded. metal tube 3
is constructed in advance to dimensions that do not take into account thermal deformation, etc., while the mold is dimensioned in consideration of solidification shrinkage of the cast iron portion 7.

Then, the entire circumference of the metal pipe 3 is wrapped with a heat insulating material 4, and it is set inside the mold, and the metal pipe 3 is undulated to the outside of the heat insulating material 4.
Section 7 is formed. At this time, the flange 3a of the metal pipe 3 is cast into the flange 6a of the collecting pipe 6 and connected to each other,
At the end of the branch pipe 2 is a branch made of metal pipe 3 and cast iron? Since the heat insulating material 4 is interposed between the metal pipe 3 and f2, the heat insulating material 4 deforms and protects the metal pipe 3 from deformation even if the cast iron portion 7 solidifies and shrinks as shown in FIG.

Since the mutual pitch p between the branch pipes of the mold is determined by taking into consideration in advance the amount of deformation due to solidification shrinkage of the branch pipe 2 made of cast iron after VI casting, solidification shrinkage occurs in the cast iron part 7, and as shown in FIG. ) i
Even if the branch pipe 2 is deformed from the state shown by the gl line to the state shown by the solid line in b), the center of the branch pipe 2 coincides with the center of the gold Ii1 pipe 3, and the cylinder head exhaust boat positional deviation can be eliminated.

[Effect of the Invention 1] As described above, the present invention provides a heat insulating material around the metal pipe, and casts the 7 flanges provided at the end of the metal pipe on the collecting pipe side into the flange of the end of the exhaust manifold on the collecting pipe side. Because it is wrapped, the heat insulating material deforms as a buffer material against the solidification shrinkage of the cast iron part after casting, and it is possible to avoid pitch changes at the branch pipe side end of the metal pipe, and
It is possible to prevent the cast iron part from directly contacting the metal pipe due to solidification shrinkage, and while it is easy to manufacture, the exhaust manifold for an internal combustion engine has an excellent heat insulation effect without contact between the metal pipe and the cast iron part on the branch pipe side. It can be provided at low cost.

Since the heat insulating material acts as a buffer against solidification shrinkage of the cast iron part and protects the metal pipe from deformation, accurate mutual pitch of the branch pipe side ends can be obtained.

Note that during casting, the insulation material relieves the solidification shrinkage force of the iron part and suppresses the deformation of the metal pipe, so after completion, if necessary, the insulation material can be removed from between the cast iron part and the metal pipe to completely It is also possible to form a heat insulating air layer.

[Brief explanation of drawings]

FIG. 1 is a plan sectional view showing a branch pipe side end of an exhaust manifold for an internal combustion engine according to the present invention, and FIG. 2 is a plan sectional view showing a schematic configuration of the exhaust manifold for an internal combustion engine. FIG. 3 is a plan sectional view showing the end of the exhaust manifold on the collecting pipe side, FIG. 4 is a front sectional view of the branch pipe, and FIG. FIG. 5 (1)) is a front view of the same, FIG. 6 is a plan sectional view of the branch pipe side end of a conventional exhaust manifold, and FIG. (a) is a plan sectional view showing the relationship between the branch pipe side end of the exhaust manifold and the metal pipe due to solidification shrinkage of the cast iron part, and Fig. 7 (b)
) is a front view of the same. 2: Branch pipe 3: Metal pipe 3a, 5a: Flange 6: Collecting pipe 7: Cast iron part 10: Exhaust manifold Patent applicant Isui Jidosha Co., Ltd. agent Patent attorney Toshio Yamamizu Figure 2 Figure 1 Figure 6 Prisoner ( b) Figure 7 dispute (b) Figure 5

Claims (1)

[Claims] A heat-resistant metal pipe is installed on the inner wall of the cast iron exhaust manifold via a heat insulating layer, and the end flange of the metal pipe is cast into the end of the collecting pipe, and the heat insulating layer is placed at the end of the branch pipe. An exhaust manifold for an internal combustion engine, characterized in that the exhaust manifold is open to the outside.