JPS63280813A - Exhaust manifold - Google Patents

Abstract

PURPOSE:To prevent leakage of gas through an exhaust gas inlet, in an exhaust manifold defining an exhaust chamber where an inner shell fixed with a flow-in tube at the exhaust inlet is covered with an outer shell through a thermal insulation layer, by forming a fixing flange in the flow-in tube. CONSTITUTION:An exhaust manifold 1 for damping pulsation of exhaust gas comprises an inner shell 5 defining an exhaust chamber 4 having exhaust inlet 2 and outlet 3, a thermal insulation layer 6 covering the outer face of the inner shell 5 and an outer shell 7 surrounding the outer face of the thermal insulation layer 6. A flow-in tube 8 is fitted at the inlet 2 and a thermal insulation layer 9 is formed around the flow-in tube 8. Here, a fixing baseboard 16 is secured to the end portion of the flow-in tube 8 at the cylinder head side of engine in order to form a fixing flange 17. The fixing baseboard 16 has such size as covering the end portion 22 of a fixing tube 21 formed integrally with the outer shell 7 and the end portion at the cylinder head side of a bolt supporting section 19.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field 1] The present invention relates to an exhaust manifold structure, and more particularly to an exhaust manifold having a heat insulating structure.

[Prior Art] In general, in the case of an internal combustion engine equipped with a turbocharger, the turbine of the turbocharger is supplied with high-temperature exhaust gas with a large amount of energy while minimizing heat loss of the exhaust gas discharged from the internal combustion engine. It is preferable to do so.

In addition, when installing a variable capacity turbocharger with movable nozzle vanes, etc., in order to minimize pressure fluctuations due to pulsation of the supplied exhaust flow, etc., it is necessary to install a to the exhaust manifold,
It is necessary to form an exhaust chamber (chamber) in which the exhaust gas is temporarily collected.

For this reason, as shown in FIGS. 4 and 5, conventionally, the exhaust manifold a collects exhaust gas from each cylinder of an internal combustion engine in an exhaust chamber C formed as a rectangular parallelepiped inner shell, and the pulsation of the exhaust gas is After buffering the exhaust gas, the exhaust gas is discharged to the downstream side, that is, to the turbocharger turbine side.

The exhaust chamber C is formed of a heat-resistant metal such as a stainless steel plate, and on the negative side thereof, an inlet d is formed along its longitudinal direction for letting exhaust gas flow in from each cylinder of the internal combustion engine. The cylinder head (not shown) is located outside of d.
An inflow pipe e is fitted and provided to communicate with the inflow pipe e. Further, on the other side, an exhaust pipe f for guiding the exhaust gas in the exhaust chamber C to the exhaust downstream side is formed.

In order to maintain the high temperature of the exhaust gas, a heat insulating layer g is formed covering the exhaust chamber C, and is made of alumina (Aβ2o
3) Fibers, etc. are used to block outward heat radiation. Furthermore, a cast iron outer shell is formed surrounding the heat insulating layer 9, and an attachment pipe is provided on the outer periphery of the inflow pipe e to cover it; and for connecting the attachment pipe i to the cylinder head. is formed in the bolt support portion for inserting the mounting bolt j from the downstream side to the cylinder head side.

Further, as shown in FIG. 6, the bolt support portion, together with the end of the mounting pipe i, forms a mounting flange for mounting on the cylinder head. The mounting pipe i covers the cylinder head side end of the inflow pipe e bent radially outward, also from the axial direction, and has sufficient support strength when mounted.

[Problems to be Solved by the Invention] Incidentally, in order to manufacture the above exhaust manifold a, the inner shell coated with the heat insulating layer 9 is cast as a core, the outer shell is molded, and this is machined. It will be processed and finished. For this reason, quality considerations such as inspecting the condition of the inner shell and the heat insulating layer 9 or replacing them depending on the condition after casting are not possible, and the total weight is large.
Difficulties arose in mass production, such as the need for transportation during machining.

For this reason, the present inventors were developing an exhaust manifold formed by dividing the outer shell.

As shown in Fig. 7, this split type exhaust manifold l
The outer shell n is divided into the cylinder head side and the exhaust downstream side, and a tightening bolt 0 is provided around them, and they are butted and connected a.
＝It is the way to do it. With this configuration, after casting the outer shell n in half, the inner shell covered with the heat insulating layer Q is set inside the outer shell n on one side, and then the other outer shell n Since it is only necessary to cover the parts with the bolts and fasten them with the tightening bolts O, the above-mentioned problems can be solved to a certain extent.

However, in this exhaust manifold, the structure of the inflow pipe e and the mounting flange 2 poses a problem.

As shown in FIG. 6, a heat insulating layer 9 is also formed around the conventional inflow pipe e. Since the end of the inflow pipe e is joined to the outer shell, this has a function of alleviating deformation (radial movement) caused by the difference in thermal expansion between them. This configuration can be formed by casting, but in the split type exhaust manifold m',
It is difficult to seal the heat insulating layer 9 around the inflow pipe e with only the tightening force of the tightening bolt 0.

Therefore, as shown in Figure 8, the insulation mg covering the inner shell
A conceivable configuration is to separately form a heat insulating layer p around the inflow pipe e and seal this with a seal ring q. However, with this configuration, exhaust gas flows into the upper part of the seal ring q, and this is the flange surface! This will cause the oil to enter the cylinder head and adversely affect the connection with the cylinder head.

For this purpose, as shown in FIGS. 9 and 10, a split seal member r is fitted in a wedge shape between the folded end of the inflow pipe e and the heat insulating layer p covering the periphery of the inflow pipe e. , and a structure in which the model plug S is fitted into the inflow pipe e has been devised. According to these, the above-mentioned insulation WIp seal and exhaust mounting flange! Regarding the inflow into the country, it will be resolved.

However, in the above solution, a step is created in the mounting flange 2 between the end of the inflow pipe e and the seal member r (see Fig. 9), and the area of the flange β is smaller than that of the conventional one (see Fig. 9). Figure 10) and other problems arise. As a result, when the exhaust manifold is attached to the cylinder head, there is a risk that exhaust gas will leak along the flange β.

In view of the above circumstances, the present invention was devised to provide an insulating exhaust manifold having a divided outer shell with a mounting flange secured therein.

[Means for Solving the Problems 1] The present invention defines an exhaust chamber having an exhaust inlet and an outlet, and forms an inner shell having an inlet pipe fitted to the inlet of the exhaust chamber,
The inner shell is coated with a heat insulating layer, the outer surface of the heat insulating layer is divided into at least two parts to form an outer shell that supports the inner shell, and a mounting board forming a mounting flange is provided at the inlet. The above-mentioned inflow pipe is fitted and joined.

[Function] The exhaust chamber defined by the inner shell allows exhaust gas to flow in from the inlet, create static pressure, and then discharge to the downstream side.

The insulation layer blocks hot exhaust heat from being transferred to the outer shell. The outer shell, which is divided into at least two parts, supports the inner shell and the heat insulating layer so as to cover them from the outside.

The mounting board forms a mounting flange with the cylinder head at the inlet [1] of the exhaust chamber, and also seals a heat insulating layer formed around the inlet pipe which fits into the inlet and is formed by -C.

[Example 1 Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIGS. 1 and 2 show an embodiment of an exhaust manifold according to the present invention. As in the conventional case, an exhaust manifold 1 has an exhaust chamber 4 having an exhaust inlet 2 and an exhaust outlet 3. It is composed of an inner shell 5, a heat insulating layer 6 covering the inner shell 5, and an outer shell 7 supporting the inner shell 5 and the heat insulating layer 6. An inlet pipe 8 is fitted into the inlet 2, and a heat insulating layer 9 is also formed around it. In this embodiment, the outer shell 7 has a cylinder head side 10 and a discharge downstream side 1.
It is divided into two parts: 1 and the supercharger turbine side. At the peripheral end 12 of the outer shell 7, there is a boss 14 extending across the vj plane 13, and a tightening bolt 1 screwed into the boss 14.
5 is provided.

The mounting board 16, which is a feature of the present invention, is provided at the end of the inflow pipe 8 on the cylinder head side 10 to form a mounting flange 17.

As shown in FIG. 3, the end 18 of the inflow pipe 8 on the exhaust chamber 4 side
The inner shell 5 on the side that partitions the exhaust chamber 4 is folded back radially outward so as to be appropriately overlapped with the inner shell 5 and is surface-joined by welding, and at the position where it contacts one bolt support part,
They are joined and welded in the same direction to the tubular portion 20 forming the mounting bolt support portion 19. Further, the heat insulating layer 9 surrounding the inflow pipe 8 is formed separately from the heat insulating layer 6 covering the exhaust chamber 4, but in the bolt support part 19, the heat insulating layer 9 surrounding the inflow pipe 8 is formed separately from the heat insulating layer 6 formed in the tubular part 20. Cylinder head side 10
It is formed as an extended end of.

The mounting board 16 is formed as a cast iron plate that covers the end of the heat insulating layer 9, and further includes the end 22 of the mounting pipe 21 integrally formed with the outer shell 7 and the bolt support portion. 19 and the end 23 of the cylinder head side 10,
The mounting flange 17 has the same area as the conventional one.

That is, it has the same shape as the end of the attachment tube, which was conventionally formed by casting. However, the opening 24 communicating with the exhaust inlet 2 is fitted into the cylinder head side 10 portion of the inflow pipe 8, and is joined at its end 25 by welding.

Next, the operation of this embodiment will be explained.

As in the past, the exhaust chamber 4 suppresses pressure fluctuations caused by pulsation of the exhaust flow, etc., and the heat insulating layer 6 suppresses pressure fluctuations caused by pulsation of the exhaust flow. The heat of the exhaust gas is blocked from being transmitted to the outer shell 7, and heat loss is reduced.

Further, since the outer shell 7 that covers and supports the inner shell 5 and the heat insulating layer 6 is divided into two parts, it can be cast separately and the inside can be opened and opened so as to be freely connected and separated.

The mounting board 16 ensures a mounting flange 17 equivalent to a conventional mounting tube end, and also seals the heat insulating layer 9 around the inflow pipe 8, thereby making it possible to buffer the effect of thermal deformation of the inflow pipe 8.

In this way, we have overcome the problem of securing a mounting flange when using a split type heat-insulating exhaust manifold by providing a mounting board, which is an advantage of splitting. This will reduce the weight of the piece, ■ prevent thermal deformation of the inner shell during the casting process, and enable on-site maintenance and inspection of the inner shell and heat insulating layer.

Note that the first substrate may be formed of a stainless steel plate instead of cast iron. Further, instead of being formed for each exhaust inlet, it may be formed continuously, that is, as a single iron plate along the longitudinal direction of the exhaust manifold.

[Effects of the Invention J] To summarize, according to the present invention, the following excellent effects are achieved.

Since a mounting board is provided at the exhaust inlet, an insulating exhaust manifold with a divided outer shell is installed on the mounting flange to prevent leakage of exhaust gas and to form a heat insulating layer around the inlet pipe. It can contribute to the practical application of

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway side view showing one embodiment of an exhaust manifold according to the present invention, FIG. 2 is a bottom view thereof, FIG. 3 is a sectional view taken along the line ■-■ in FIG. 2, and FIG. The figure is a partially cutaway side view showing a conventional exhaust manifold, Figure 5 is a top view thereof, Figure 6 is a sectional view taken along the line Vl-VI in Figure 5 at υ2, and Figure 7 is a split J-type exhaust manifold. The schematic diagrams shown in FIGS. 8 to 10 are explanatory diagrams for explaining the problems of the split type exhaust manifold. In the figure, 1 is an exhaust manifold, 2 is an exhaust inlet, 4 is an exhaust chamber, 5 is an inner shell, 6 and 9 are heat insulation layers, 8 is an inflow pipe, 16 is a mounting board, and 17 is a mounting flange. Patent Applicant: Izubo Jidosha Co., Ltd. Sanwa Kinzoku Kogyo Co., Ltd. Representative Patent Attorney: Kinutani (Ej)

Claims (1)

[Claims] An inner shell is formed which defines an exhaust chamber having an exhaust inlet/outlet and an inflow pipe fitted to the inlet, the inner shell is coated with a heat insulating layer, and the outer surface of the heat insulating layer is divided into at least two parts. An exhaust manifold comprising: an outer shell that supports the inner shell; a mounting board forming a mounting flange at the inlet; and a fitting board and the inflow pipe connected to each other.