JPH0540261Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an exhaust manifold structure, and more particularly to an insulating exhaust manifold structure formed to have durability.

[Prior Art] Generally, in the case of an internal combustion engine equipped with a turbocharger,
It is desirable to suppress heat loss of the exhaust gas discharged from the internal combustion engine as much as possible and supply high-temperature exhaust gas with a large amount of energy to the turbine of the turbocharger. 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, the exhaust gas connected to the cylinder located upstream of the It is necessary to form an exhaust chamber in the manifold to temporarily collect the exhaust gas.

Therefore, as shown in FIGS. 5 and 6,
Conventionally, the exhaust manifold a collects exhaust gas from each cylinder of an internal combustion engine into an exhaust chamber c formed as a rectangular parallelepiped inner shell b, buffers its pulsation, and then transfers the exhaust gas to the downstream side, that is, the supercharger turbine. It is designed to flow out to the side.

The exhaust chamber c is formed of a heat-resistant metal such as a stainless steel plate, and on one side of the exhaust chamber c, an inlet d is formed along its longitudinal direction for allowing exhaust gas to flow in from each cylinder of the internal combustion engine. An inflow pipe e is provided outside d for communicating with a cylinder head (not shown). Also, on the other side, there is 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 to cover the exhaust chamber c, and is made of alumina (Al ₂ O ₃ ) fiber or the like to block heat radiation to the outside. There is. Furthermore, a cast iron outer shell h is formed surrounding the heat insulating layer g, and an inflow pipe e is formed.
A mounting pipe i is provided on the outer periphery of the
and a bolt support part k through which a bolt j for connecting the mounting pipe i to the cylinder head is inserted from the downstream side to the cylinder head side.

[Problems to be solved by the invention] By the way, in the above-mentioned exhaust manifold structure, the temperature of the exhaust gas in the exhaust chamber c is 850°C.
The temperature of the inner shell b that partitions the exhaust chamber c is raised to about 800°C by this heat. Although heat input to the outer shell h is prevented by the heat insulating layer g, the temperature remains around 500°C. Therefore, inner shell b and outer shell h
The stainless steel plate and cast iron that form each expand thermally, but the degree of thermal expansion differs due to the above temperature difference and the difference in linear expansion coefficient of each. A tensile force due to the difference in the amount of deformation is applied to the end of the pipe e, which may cause cracks or the like to occur, causing the exhaust gas in the exhaust chamber c to leak.

In addition, due to repeated expansion and contraction of the exhaust gas in the exhaust chamber c or vibrations depending on the operating condition of the internal combustion engine, the heat insulating material (alumina fiber) forming the heat insulating layer g moves, and the inner shell b There was a problem in that a void was formed between the outer shell h and the heat insulation properties were reduced.

Furthermore, on the downstream side of this exhaust manifold a,
If an exhaust brake is provided to close the exhaust pipe, the pressure within the exhaust chamber c reaches a maximum of about 6 kg/cm ² when the exhaust brake is activated.

As shown in FIG. 7, the inner shell b expands irregularly due to this internal pressure so as to push away the heat insulating layer g, and is deformed as indicated by the broken line A in the figure. As this deformation progresses, the inner shell b comes into contact with the inner wall of the outer shell h, and the heat insulating effect is reduced. In addition, an inner shell b is formed by partitioning the radially outer side of the bolt support part k.
The ends are joined to the inner shell b on the cylinder head side and discharge downstream side, which are perpendicular to this, in surface contact, and the above deformation deteriorates this joint and causes cracks. There is a risk of exhaust gas leaking.

Therefore, the present invention was devised to provide a heat-insulating exhaust manifold structure that prevents the deformation of the inner shell, which is the problem described above, and improves durability.

[Means for solving the problem] The present invention forms an inner shell that is connected to the cylinder head and defines an exhaust chamber for collecting and discharging exhaust gas from each cylinder, and a heat insulating layer is provided on the inner shell. The outer shell is coated on the heat insulating layer, and a part of the inner shell is folded back so as to protrude into the heat insulating layer.

[Operation] The exhaust chamber collects exhaust gas from each cylinder and guides it to the exhaust downstream side. The insulation layer blocks hot exhaust heat from being transferred to the outer shell.

The part of the inner shell that is folded back and protruding absorbs the deformation of the inner shell, which has a larger amount of thermal expansion than the outer shell, and reduces the effect on the joint with the outer shell. Further, movement of the heat insulating layer is prevented by supporting it with the protruding portion. Furthermore, since the protrusion reinforces the inner shell, deformation due to internal pressure is suppressed.

[Examples] Examples of the present invention will be described below with reference to the accompanying drawings.

Figures 1 and 2 show one embodiment of an exhaust manifold structure according to the present invention. As in the conventional case, the exhaust manifold 1 is connected to the cylinder head to collect and discharge the exhaust from each cylinder. The exhaust manifold 1 is formed of an exhaust chamber 3 partitioned by an inner shell 2 formed in a rectangular parallelepiped shape, an insulating layer 4 covering the inner shell 2, and an outer shell 5 further covering the insulating layer 4.

One side of the inner shell 2, that is, the cylinder head side 6, is provided with an inlet 7 and an inlet pipe 8.
On the other side, that is, on the exhaust downstream side 9, there is a discharge pipe 10.
is formed. Further, the outer shell 5 includes an attachment pipe 11 formed to surround the inflow pipe 8, and an attachment pipe 1 formed to surround the inflow pipe 8.
A bolt support part 13 is provided for supporting a bolt 12 that is inserted so as to sandwich the bolt 1 .

The side plate 14 of the inner shell 2 is a feature of the present invention.
A protrusion 15 that protrudes into the heat insulating layer 4 and is folded back is formed in a part of the heat insulating layer 4 . In this embodiment, as shown by a two-dot chain line B in the figure, the exhaust manifold 1 is arranged along the longitudinal direction of the exhaust manifold 1 and in a direction perpendicular thereto, avoiding the inlet 7 and the bolt support part 13. It is folded back in a grid pattern.

As shown in FIGS. 3 and 4, the inner shell 2 is formed from a stainless steel plate, and the folding is done by beading that is protruded into a string shape. The cross-sectional shape of the protruding portion 15 is approximately U-shaped, and its tip 16 is appropriately spaced from the inner side 17 of the outer shell 5 and secured within the heat insulating layer 4, and the side surface 18 is attached to the side plate 14 of the inner shell 2. In the direction along this line, in FIG. 4, it crosses the vertical direction.

Next, the operation of this embodiment will be explained.

The exhaust chamber 3 collects exhaust gas from each cylinder,
Suppresses pressure fluctuations caused by exhaust flow pulsation, etc. The heat insulating layer 4 blocks the heat of this high-temperature exhaust gas from being transmitted to the outer shell 5, thereby reducing heat loss of the exhaust gas.

When the inner shell 2 is heated by high-temperature exhaust gas and thermally expands to a greater degree than the outer shell 5, the protrusion 15 deforms itself so that it expands into the heat insulating layer 4. It is absorbed by the outer shell 5
Prevent the spread to the joints.

In addition, due to repeated expansion and contraction of the inner shell 2 and vibrations caused by the operation of the internal combustion engine, the heat insulating material (alumina fiber, etc.) forming the heat insulating layer 4 gradually wears away from the side plate 1.
4, but the side surface 18 of the protrusion 15 blocks this movement (displacement) and prevents the formation of a gap.

Furthermore, the well-known reinforcing function of the protrusion 15 formed by beading prevents deformation of the inner shell 2 due to an increase in pressure within the exhaust chamber 3 when the exhaust brake is activated.

The above-mentioned effect is also exhibited in the "exhaust pipe structure" (Japanese Patent Application No. 162058/1982) proposed earlier by the inventors of the present invention. However, in that proposal, since the tip of the bead portion corresponding to the protrusion 15 of the present invention is configured to be in contact with the inside of the outer tube (outer shell), the heat insulation effect is reduced due to heat transfer at this contact portion. There is a risk. In contrast, in the present invention, the tips are folded back without contacting each other, so as long as there is no excessive protrusion (contact) due to progress of expansion, the above-mentioned adiabatic effect will not deteriorate.

[Effects of the Invention] In summary, the present invention provides the following excellent effects.

(1) A part of the conventional inner shell that partitions the exhaust chamber is folded back, which absorbs deformation caused by thermal expansion of the inner shell, prevents damage to the joints with the outer shell, and improves durability. A thermally insulating exhaust manifold structure can be obtained.

(2) Since the folds are made to protrude into the heat insulating layer, it is possible to prevent the movement of the heat insulating material, prevent the deterioration of the heat insulating property due to the formation of voids in the heat insulating layer, and improve durability.

(3) Since the protruding portion increases the strength of the inner shell, it is possible to prevent deformation of the inner shell due to increased pressure in the exhaust chamber and improve durability.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway side view showing an embodiment of an exhaust manifold structure according to the present invention, FIG. 2 is a top view thereof, and FIG. 3 is a sectional view taken along the line - in FIG.
Fig. 4 is an enlarged view of the main part, Fig. 5 is a partially cutaway side view showing a conventional exhaust manifold structure, Fig. 6 is a top view thereof, and Fig. 7 is a sectional view taken along the line - in Fig. 6. . In the figure, 1 is an exhaust manifold, 2 is an inner shell, 3 is an exhaust chamber, 4 is a heat insulation layer, 5 is an outer shell, 14 is a side plate, 1
5 is a protrusion.

Claims (1)

[Claims for Utility Model Registration] (1) An inner shell is formed that is connected to the cylinder head and defines an exhaust chamber for collecting and discharging exhaust gas from each cylinder, and the inner shell is coated with a heat insulating layer. An exhaust manifold structure, characterized in that the heat insulating layer is covered with an outer shell, and a part of the inner shell is folded back so as to protrude into the heat insulating layer. (2) The inner shell is formed from a stainless steel plate,
The exhaust manifold structure according to claim 1, wherein the protruding portion folded back into the heat insulating layer is formed by beading. (3) The exhaust manifold structure according to claim 2, wherein the protruding portion is formed in a lattice shape on the side plate of the inner shell.