JPH07293236A - Exhaust device for internal combustion engine - Google Patents

Abstract

PURPOSE:To provide an exhaust device for an internal combustion engine to absorb the relative displacement between exhaust system members caused by difference in the coefficiency of thermal expansion of materials. CONSTITUTION:Two kinds of bolt holes 10, 11 are formed in each of four corners of a turbine housing mounting surface 8. That is, a locating hole 10 having the diameter somewhat larger than that of a bolt 5 is formed left below an exhaust port 9 as viewed in the drawing, and escapement holes 11 in which the bolt 5 is loosely fit are formed in the other three portions. The escapement hole 11 is a slot extending longitudinally along a straight lines La, Lb, Lc interconnecting the center of the escapement hole 11 and the center of the locating hole 10 and the bolt 5 is formed to be located near the locating hole 10 in cold time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust system for an internal combustion engine used in automobiles and the like.

[0002]

2. Description of the Related Art In recent years, many gasoline engines and diesel engines are equipped with a turbocharger in order to achieve both small size and light weight and high output. A turbocharger rotates a turbine wheel with exhaust gas, and supercharges with a compressor impeller coaxial with a turbine wheel. As shown in FIG. 9, the main body of the turbocharger includes a turbine housing 1 that houses a turbine wheel and a compressor housing 2 that houses a compressor impeller. The turbine housing 1 is interposed between the exhaust manifold 3 and the front pipe 4 and is provided with bolts 5 and 5, respectively.
It is concluded by 6.

Generally, the compressor housing 2 through which relatively low temperature intake air flows is a cast product of aluminum alloy, but the turbine housing 1 through which high temperature exhaust gas flows
For the exhaust manifold 3, a cast iron-based material is used in terms of heat resistance and mass productivity. For example, Niresist (nickel chrome cast iron) having excellent high temperature corrosion resistance is used for the turbine housing 1, and FCD (spheroidal graphite cast iron) having excellent high temperature durability and economy is used for the exhaust manifold 3.

[0004]

Generally, the coefficient of thermal expansion of the niresist is 30% or more higher than that of the FCD, and the turbine housing 1 is operated in the cold condition equal to the outside temperature and in the operation condition of about 900 ° C. A large relative displacement occurs between the exhaust manifold 3 and the exhaust manifold 3. However, since the turbine housing 1 and the exhaust manifold 3 are constrained to each other through the bolts 5, their free deformation is prevented and thermal stress of compression or tension acts on both. Therefore, as shown in FIG. 9, on the side of the exhaust manifold 3 which is intermittently subjected to tensile stress when it is operated for a long period of time, as shown in FIG.
There is a risk that cracks 7 may occur due to fatigue and cause exhaust gas leakage.

The present invention has been made in view of the above circumstances,
An object of the present invention is to provide an exhaust system for an internal combustion engine that absorbs relative displacement between exhaust system members due to a difference in thermal expansion coefficient of materials.

[0006]

Therefore, according to claim 1 of the present invention, in an exhaust system of an internal combustion engine in which exhaust system components having different thermal expansion coefficients are fastened by a plurality of bolts, at least one of the exhaust system components is provided. A bolt hole through which the bolt penetrates, and at least one of these bolt holes is used as a positioning hole for positioning the exhaust system components with respect to each other by the bolt penetrating, and bolt holes other than the positioning hole Is larger than the positioning hole to form a relief hole into which the bolt is loosely fitted.

According to a second aspect of the present invention, in the exhaust device according to the first aspect, the relief hole is a long hole or a round hole. Further, according to a third aspect of the present invention, in the exhaust device according to the second aspect, the escape hole is an elongated hole whose longitudinal direction is substantially along a straight line connecting the center of the escape hole and the center of the positioning hole.

[0008]

In the exhaust system according to the first aspect of the present invention, the positioning holes allow the exhaust system parts to be positioned relative to each other for easy assembly, while the exhaust system parts are exposed to the hot exhaust gas, so that heat is generated between the exhaust system parts. Even if a relative displacement occurs due to a difference in expansion coefficient, the bolt moves in the escape hole to allow sliding on the joint surface of the exhaust system component, and the relative displacement is absorbed.

Further, in the exhaust device according to the second aspect, since the escape hole is a long hole or a round hole, it is relatively easy to manufacture the core when casting the exhaust system component. Further, in the exhaust device of claim 3, when the relative displacement occurs between the exhaust system components, the bolt fitted in the escape hole moves along the longitudinal direction of the escape hole.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings. In the description of the embodiments, the same members as those of the conventional device described above are designated by the same reference numerals, and duplicated description will be omitted. FIG. 1 shows a main part of an embodiment of an exhaust system according to the present invention, and reference numeral 8 in the drawing denotes a turbine housing mounting surface. As shown in the figure, the turbine housing mounting surface 8 is rectangular, a circular exhaust port 9 is formed in the center, and two types of bolt holes 10 and 11 are formed at each of four corners. . That is, a positioning hole 10 having a diameter slightly larger than the outer diameter of the bolt 5 is formed at the lower left of the exhaust port 9 in the figure, and a relief hole 11 into which the bolt 5 is loosely fitted is formed at the other three positions. There is. The escape hole 11 is an elongated hole whose longitudinal direction is along straight lines La, Lb, Lc connecting the center of the escape hole 11 and the center of the positioning hole 10,
In addition, the bolt 5 is formed so as to be positioned near the positioning hole 10 when cold.

On the other hand, as shown in FIG. 2 (II-II sectional view in FIG. 1), a screw hole 13 is formed in the flange portion 12 of the turbine housing 1, and the screw hole 13 is formed in the exhaust manifold 3. A long bolt 5 penetrating a boss 14 formed in the above is screwed. The turbine housing mounting surface 8 and the end surface 15 of the flange portion 12 are both smoothed so that they can be easily slid. Also,
Bolt head 16 and bolt bearing surface 1 on exhaust manifold 3 side
A relatively thick flat washer 18 is interposed between the flat washer 18 and the plate 7. The bolt seat surface 17 is finished to be smooth so that the flat washer 18 can easily slide.

The operation of this embodiment will be described below. When the internal combustion engine is operated and hot exhaust gas flows, the temperature of the exhaust manifold 3 and the turbine housing 1 becomes 90%.
It reaches about 0 ° C. This allows the exhaust manifold 3
And the turbine housing 1 both thermally expand, but the exhaust manifold 3 expands more than the turbine housing 1 due to the difference in the coefficient of thermal expansion described above. Then, the turbine housing mounting surface 8 of the exhaust manifold 3 and the flange portion 12 of the turbine housing 1 are arranged in the manner shown in FIG.
It is relatively displaced as shown in the section IV-IV). That is, the lower left portion in FIG. 3 is constrained by the positioning hole 10, and in other portions, the exhaust manifold 3 uniformly expands with respect to the turbine housing 1 around the positioning hole 10.

As a result, the turbine housing mounting surface 8 and the end surface 15 of the flange portion 12 slide on each other, while the bolts 5 loosely fitted in the relief holes 11 are straight lines La, Lb, Lc.
And moves in the direction away from the positioning hole 10. At this time, since the turbine housing mounting surface 8 and the end surface 15 of the flange portion 12 easily slide, the exhaust manifold 3
Of the turbine housing 1 is smoothly expanded,
Almost no tensile stress acts on the exhaust manifold 3. Similarly, the bolt bearing surface 17 on the exhaust manifold 3 side and the flat washer 18 easily slide, so that the bolt 5 has a clearance hole 1
The bolt 5 is moved substantially parallel to the inside of the bolt 1, and no bending stress acts on the bolt 5. Since the flat washer 18 is a relatively thick plate, plastic deformation due to the tightening of the bolt 5 is less likely to occur. In this embodiment, by adopting such a configuration, the exhaust manifold 3 crack 7 is not generated even when the operation is performed for a long time.

Although the description of the representative embodiment has been completed, the present invention is not limited to this embodiment, and various modes can be adopted based on the description of the claims. For example, in the above-mentioned embodiment, the bolt hole is composed of the positioning hole and the escape hole of the elongated hole. However, as shown in FIG. 5, only the escape hole 11 of the elongated hole is used, or shown in FIG. As described above, the positioning hole and the round hole relief hole 19 may be formed. Further, as shown in FIG. 7, the present invention may be applied to the turbine housing 1 and the exhaust manifold 3 that are fastened with three bolts 5, or as shown in FIG. The present invention may be applied to the front pipe 21 or the like that is fastened via the two stud bolts 20 that are planted.

[0015]

According to the exhaust device of claim 1 of the present invention,
Even if the exhaust system parts are exposed to high-temperature exhaust gas and relative displacement occurs due to the difference in the thermal expansion coefficient between the exhaust system parts, the bolts move in the relief holes and can slide on the joint surface of the exhaust system parts. The relative displacement is absorbed. As a result, cracking of exhaust system parts due to tensile stress does not occur even after long-term operation.

Further, in the exhaust device according to the second aspect, since the escape hole is a long hole or a round hole, it is relatively easy to manufacture the core when casting the exhaust system component, and the manufacturing man-hour and cost are reduced. Be reduced. Further, in the exhaust device according to the third aspect, when the relative displacement occurs between the exhaust system components, the bolt fitted in the escape hole moves along the longitudinal direction of the escape hole.
Therefore, even when the engine is operated for a long period of time, the relative positions of the exhaust system components do not change, and it is difficult for interference with surrounding components to occur.

[Brief description of drawings]

FIG. 1 is a front view of a main portion of an embodiment of an exhaust device according to the present invention at room temperature.

FIG. 2 is a sectional view taken along line II-II in FIG.

FIG. 3 is a front view of a main part of an embodiment of the exhaust device according to the present invention at a high temperature.

4 is a sectional view taken along line IV-IV in FIG.

FIG. 5 is a front view showing a main part of another embodiment of the present invention at room temperature.

FIG. 6 is a front view showing a main part of another embodiment of the present invention at room temperature.

FIG. 7 is a front view showing a main part of another embodiment of the present invention at room temperature.

FIG. 8 is a front view showing a main part of another embodiment of the present invention at room temperature.

FIG. 9 is a front view showing an assembled state of an exhaust manifold and a turbocharger.

[Explanation of symbols]

 1 Turbine Housing 3 Exhaust Manifold 5 Bolt 8 Turbine Housing Mounting Surface 9 Exhaust Port 10 Positioning Hole 11, 19 Relief Hole 12 Flange 16 Bolt Head 17 Bolt Seat 20 Stud Bolt 21 Front Pipe

Claims (3)

[Claims] 1. An exhaust system for an internal combustion engine, wherein exhaust system components having different thermal expansion coefficients are fastened together by a plurality of bolts.
Forming a bolt hole through which the bolt penetrates in at least one of the exhaust system parts, and further as a positioning hole for positioning the exhaust system parts with respect to each other by penetrating at least one of these bolt holes, An exhaust device for an internal combustion engine, wherein a bolt hole other than the positioning hole is made larger than the positioning hole to form a relief hole into which the bolt is loosely fitted. 2. The exhaust system for an internal combustion engine according to claim 1, wherein the relief hole is a long hole or a round hole. 3. The exhaust gas of an internal combustion engine according to claim 2, wherein the escape hole is a long hole whose longitudinal direction is substantially along a straight line connecting the center of the escape hole and the center of the positioning hole. apparatus.