JPS6233947Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a joint structure between a catalyst container and an exhaust manifold in an internal combustion engine.

In order to reduce unburned harmful components (HC, CO) in exhaust gas, a monolithic catalyst (generally a catalyst supported on the surface of a honeycomb catalyst carrier) is housed in a catalyst container and placed at the outlet of the exhaust manifold. Catalytic devices connected to are well known.

One such catalyst device is the device shown in FIG. 1 (see Japanese Utility Model Application No. 58-66108, which was published as Utility Model Application No. 56-160189). To explain this, the catalyst is supported in the cylindrical catalyst container 1 via an inorganic fiber heat-resistant cloth 2 placed on the inner peripheral surface of the outlet side as a buffer material and a wire mesh 3 placed on the inner peripheral surface of the inlet side. A honeycomb type catalyst carrier 4 is housed therein. An annular catalyst cap 7 is inserted between the edge of the exhaust inlet surface of the catalyst carrier 4 and the edge of the wire mesh 3.
It is adapted to be locked to a flange portion 9 of the exhaust manifold 8. Here, the catalyst cap 7 has a U-shaped cross section, and its interior (catalyst carrier 4 side)
is filled with wire mesh 17. This also applies to the catalyst cap 5 that maintains the exit direction of the catalyst carrier 4.

Further, a counterbore groove 18 is formed on the inner edge side of the flange portion 11 of the catalyst container 1, and a heat-resistant O-ring 1 made of a metal pipe such as stainless steel is inserted into the groove 18.
9 is inserted. Therefore, catalyst container 1
The inner edge side of the flange portion 11 contacts the flange portion 9 of the exhaust manifold 8 via a metal heat-resistant O-ring 19.

Furthermore, the outer edge side of the flange portion 11 of the catalyst container 1 is formed with a surface contact portion 20 with the flange portion 9 of the exhaust manifold 8, and both the flange portions 9 and 11 are in surface contact at this portion, and the stud bolt 13 and the nut It is tightened and fixed by 14.

Thus, the flange portion 9 of the exhaust manifold 8
and the flange portion 11 of the catalyst container 1 are, in order from the inside, the catalyst cap 7 and the metal heat-resistant O-ring 1.
9 and the surface contact portion 20 form a concentric seal portion, which reliably prevents leakage of exhaust gas.

Incidentally, in order to ensure the strength of the flange portion 11 and reduce its weight, it is necessary to move the stud bolts 13 as close to the inner circumferential side as possible. Therefore, the step wall 21 and the stud bolt 13, which are provided on the outer periphery of the counterbore ring groove 18 of the heat-resistant O-ring 19 and are used to restrict the amount of crushing of the heat-resistant O-ring 19, come closer to each other.

However, if this is done, when the stud bolt 13 is fitted into the screw hole 25 of the flange portion 11 before installing the catalyst container 1 to the exhaust manifold 8, if the tightening force is increased, the incomplete screw portion 29 will be inserted into the screw hole 25. The upper edge is pushed out, causing cracks in the thin step wall 21, sagging of the surface, and inward bulge of the mounting surface, which causes the heat-resistant O-ring 19
However, there has been a problem in that the nut 14 loosens due to changes in the tightening force over time.

This invention creates a counterbore hole in the threaded hole of the flange and makes the counterbore surface the same as or deeper than the ring groove bottom of the heat-resistant O-ring. The purpose of this invention is to solve the above problems by preventing the above problems.

An embodiment of the present invention will be described below based on FIG. 2. (However, the same components as in FIG. 1 are given the same reference numerals.) Stud bolts 1 formed on the flange portion 11
Countersink hole 2 by counterboring the screw hole 25 of No. 3.
form 7. The diameter of the counterbore hole 27 is formed to be larger than the maximum diameter of the stud bolt 13, so that the bottom surface 27a, that is, the stop position 24 of the incompletely threaded portion 29 of the stud bolt 13, is aligned with the O-ring groove 18 against the flange surface 22. The depth should be the same as the groove bottom 23.

In addition, the depth of the countersunk hole 27 is increased so that the stop position 24 of the incomplete thread portion 29, i.e., the bottom surface 27a of the countersunk hole, is positioned relative to the flange surface 22 in the O-ring groove 18.
It may be made deeper than the groove bottom 23 .

As described above, if the stop position 24 of the incompletely threaded portion 29 is made deeper than the groove bottom 23 of the O-ring groove 18, when the stud bolt 13 is tightened to the flange portion 11, the incompletely threaded portion 29 will be inserted into the threaded hole 25. Even if the upper edge is crushed, the bottom surface 27a of the counterbore hole 27 will not be deformed. Therefore, the step wall 21 on the outer periphery of the O-ring groove 18 into which the heat-resistant O-ring 19 is fitted will not fall toward the inner periphery or crack when the stud bolt 13 is tightened.

As described above, the present invention provides a counterbore hole in a part of the threaded hole of the flange, and the bottom surface of the hole is designed to prevent the incompletely threaded part of the stud bolt from interfering with the step wall on the outer periphery of the thin-walled heat-resistant O-ring. Because the depth is deep, stress is not directly applied to anything other than the flange surface of the manifold, which prevents distortions such as warping and sagging of the step wall, preventing problems with installing heat-resistant O-rings, and preventing studs from being exposed to stress directly from sources other than the flange surface of the manifold. It is possible to prevent the tightening force of the bolts and nuts from decreasing, and it is possible to obtain the effect of reliably preventing leakage of exhaust gas from the joint between the exhaust manifold and the catalyst container.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a conventional device. FIG. 2 is a sectional view of the present invention. DESCRIPTION OF SYMBOLS 1... Catalyst container, 9... Flange part of exhaust manifold, 11... Flange part of catalyst container, 13
... Stud bolt, 18 ... O-ring groove, 19
...Heat-resistant O-ring, 25...Screw hole, 27...
Spot facing hole.

Claims (1)

[Scope of utility model registration request] An O-ring groove that accommodates a heat-resistant O-ring placed on the inner edge of the flange of the catalyst container that houses the honeycomb catalyst carrier inside, and a surface contact portion formed on the outer edge of the flange of the catalyst container are connected to the flange of the exhaust manifold. In the structure of the joint between the exhaust manifold and the catalyst container, in which the catalyst container and the exhaust manifold are pressed together concentrically and fixed by tightening stud bolts, the studs are formed at the surface contact part on the outer edge side of the flange of the catalyst container. A joint between an exhaust manifold and a catalyst container, characterized in that a part of the screw hole of the bolt is provided with a counterbored hole, and the bottom of the counterbored hole is formed deeper than the bottom of the O-ring groove that accommodates the heat-resistant O-ring. structure.