JPH0426650Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention relates to a monolithic catalytic converter, particularly to a holding mechanism for a nozzle for supplying secondary air.

(Conventional technology) CO from the exhaust manifold to the catalytic converter,
There is a secondary air introduction device that supplies air to the exhaust system as secondary air to perform the oxidation reaction of HC. In this device, air is introduced using pressure pulsations generated in the exhaust manifold by exhaust gas discharged from the engine. That is, the air cleaner and the exhaust manifold are connected via a secondary air supply pipe, and a reed valve (also serving as a check valve) is interposed in the middle. With this configuration, when the pressure within the exhaust manifold periodically becomes lower than atmospheric pressure, the reed valve opens, thereby introducing air into the exhaust manifold.

One of the monolithic catalytic converters constituting such a device is shown in FIGS. 4 and 5 (see, for example, Japanese Utility Model Application Publication No. 129914/1988).

To explain this, FIG. 4 is an external view of the monolithic catalytic converter, and FIG. 5 is a sectional view taken along the line A--A in FIG. 4. A plurality of monolith catalysts 4 and 5 are arranged at a predetermined interval in the axial direction of the casing 1 in a cylindrical casing 1 having an inlet 2 and an outlet 3 for exhaust gas in the front and rear (left and right directions in the figure). arranged in series with
A secondary air supply nozzle 8 is provided in the direction crossing the above-mentioned interval.
is provided so as to be located at the center of the casing 1. This nozzle 8 is fixed to the casing 1 via a short pipe 7. That is, a thin cylindrical short pipe 7 is welded and fixed to the casing 1, and the short pipe 7 has a nozzle 8 consisting of a bent pipe having a number of holes 10 on the downstream side, and a flange pipe having a flange 11 at the upstream end. 9 are welded and fixed. Furthermore, the flange pipe 9 has a flange 1 at the downstream end.
3 and a secondary air supply pipe 12 having a flange connection. Note that W indicates a welded location. Therefore, supply pipe 1
2. The air diffused into the exhaust stream from the hole 10 of the nozzle 8 via the flange pipe 9 mixes with the exhaust gas that has passed through the reduction monolith catalyst 4, and with the help of the oxidation monolith catalyst 5 provided downstream, unburned gas is removed. It promotes oxidation.

(Problem to be solved by the invention) In such a monolithic catalytic converter, the short pipe 7 is fixed to the casing 1 by welding between thin-walled members, so welding strain or residual stress remains in the joint. This area becomes a weak area. However, since fixing to the casing 1 relies only on this joint, and furthermore, the connecting flanges 11 and 13 are separated from the joint, for example, when a load or vibration is applied to the supply pipe 12, these loads Since the welded joints of the short pipes 7 are subjected to stress concentration and vibrations directly act on the joints, and the joints take on all of these loads, cracks are likely to occur from the joints. There is. However, in order to reinforce this point, nozzle 9
It is not a good idea to add another auxiliary support mechanism for fixing because it increases the number of component parts and also increases the number of assembly steps.

Furthermore, if the strength of the welded joint between the short pipe 7 and the casing 1 or the nozzle 8 is increased by increasing the thickness of the short pipe 7, the weight of the short pipe 7 itself increases, and the welded joint with the casing 1 increases. The durability of the parts will decrease.

Furthermore, since the flange pipe 9 protrudes from the outside of the casing 1, it becomes a hindrance during assembly and transportation, resulting in poor workability and reduced productivity.

This idea was developed with a focus on these conventional problems, and the purpose is to provide a nozzle support mechanism that improves the strength of fixing the nozzle to the casing and at the same time improves workability. shall be.

(Means for solving the problem) This invention is a cylindrical casing equipped with an exhaust gas inlet and an exhaust gas outlet at the front and rear, and a plurality of monolithic catalysts are arranged in series in the axial direction of the casing at predetermined intervals. In a monolithic catalytic converter in which a secondary air supply nozzle is provided in a direction transverse to the above-mentioned interval, a cylindrical boss member having a flange formed on one side is attached to a casing wall whose one side of the flange maintains the above-mentioned interval. At the same time, the nozzle is fixed to the side of the boss member that protrudes into the casing, and a secondary air supply pipe is detachably attached to the side that protrudes outside the casing. .

(Function) When one side of the flange formed on the cylindrical boss member comes into contact with the casing wall, the load of the nozzle and the load received from the supply pipe are dispersed on this contact surface, so that the boss member and the casing are welded together. Stress concentration on only the joints is alleviated, improving attachment strength.

In addition, when the connection of the secondary air supply pipe to the catalytic converter is located adjacent to the boss member, the load and vibration acting on the secondary air supply pipe are reduced due to the large contact area between the flange of the boss member and the casing. Since the load is received through the load, excessive loads are not concentrated.

On the other hand, when the secondary air supply pipe is detached, the flange of the boss member does not protrude significantly from the casing, so it does not get in the way during assembly to a vehicle or transportation.

(Embodiment) FIG. 1 is an external view of a monolithic catalytic converter according to a first embodiment of this invention, and FIG. 2 is a sectional view taken along line A--A in FIG. 1. A plurality of monolith catalysts 4 and 5 are arranged at a predetermined interval in the axial direction of the casing 1 in a cylindrical casing 1 having an inlet 2 and an outlet 3 for exhaust gas in the front and rear (left and right directions in the figure). are arranged in series. A thick cylindrical boss portion 20 having a flange 21 formed on the upstream side is welded and fixed to the casing 1 that maintains the above-described spacing. Next, a secondary air supply nozzle 8 consisting of a bent pipe having a large number of holes 10 at one end is welded and fixed to the boss portion 20 so that the nozzle 8 crosses the above-mentioned interval and is located in the center of the casing 1. establish. Furthermore, the boss portion 20 is connected by a flange to a secondary air supply pipe 12 into which secondary air from an air cleaner (not shown) is introduced. That is, the downstream end of the supply pipe 12 is fitted through the flange 23 to the flange 21 of the boss part, and the flange 23 is welded and fixed to the supply pipe 12, and this flange 23 and the flange 21 of the boss part 20 are connected by a gasket 24. Fasten with a through bolt 25. Note that W indicates a welded location.

To describe the functions and effects of such a configuration, in the conventional example, stress concentrates on the welded joint, reducing the strength at this area, whereas in this example, the boss portion 20 to which the nozzle 8 is fixed is attached to the flange. 21
Since the flange 21 abuts against the casing wall and has a wide contact area with the casing 1, stress concentration on the welded joint between the boss portion 20 and the casing 1 is alleviated. In addition, in the conventional example, the connecting flange is separated from the welded joint, so
For example, when a load or vibration acts on the supply pipe 12, these loads or vibrations directly act on the joint,
The joint takes on all of these loads, resulting in stress concentration at the joint. On the other hand, in this example, since the connecting flanges 21 and 23 are located adjacent to the boss portion 20, the load and vibration acting on the supply pipe 12 are transferred to the casing via the wide contact area between the flange 21 and the casing 1. 1 will be subjected to the load, so an excessive load will not be applied only to the joint.

Next, in the conventional example, the downstream end of the supply pipe 12 does not protrude through the flange 13, but in this example, the downstream end of the supply pipe 12 passes through the flange 23 and also fits into the flange 21 of the boss part. Therefore, when a load or vibration is applied to the supply pipe 12, it is possible to receive the load over a wide contact area with the flanges 21 and 23, reducing the load acting on the welded joint between the supply pipe 12 and the flange 23. This improves the durability of the supply pipe 12.

Furthermore, in the conventional example, the flange pipe 9 protrudes outside the casing 1, which becomes a hindrance during assembly and transportation, whereas in this example, the flange does not protrude significantly outside the casing 1, so it is easy to transport to the vehicle. This makes it easier to absorb during assembly and transportation, improving work efficiency and productivity.

FIG. 3 is a sectional view of a second embodiment of this invention, and corresponds to FIG. In this example, the boss part 3 has a male thread formed on the upstream side, whereas the first embodiment had a flange connection between the boss part and the secondary air supply pipe.
0 and a nut 31. In this example, a large contact area is ensured between the boss portion 30 and the casing 1, and the load from the nozzle 8 and the supply pipe 12 is reduced by this contact area, so the strength is maintained as in the first example. However, since the boss portion 30 can be welded to the casing 1 from the outside, it may be easier to manufacture than the first embodiment if, for example, the shape of this portion is restricted. It will be advantageous.

(Effects of the invention) In this invention, a cylindrical boss member having a flange formed on one side is fixed so that one side of the flange is in contact with a casing wall that maintains a predetermined distance, and the boss member is The nozzle is fixed to the side that protrudes into the casing, and the secondary air supply pipe is detachably attached to the side that protrudes outside the casing, thereby preventing stress concentration or excessive load from acting. This makes it possible to increase the strength of attachment of the nozzle to the casing and improve durability, and also to facilitate handling during assembly and transportation, thereby increasing workability and productivity.

[Brief explanation of the drawing]

Figure 1 is an external view of a monolithic catalytic converter according to the first embodiment of the present invention, Figure 2 is a sectional view taken along line A-A in Figure 1, and Figure 3 is a second embodiment of the present invention. FIG. 3 is a corresponding cross-sectional view. Figure 4 is an external view of a conventional monolithic catalytic converter, and Figure 5 is A- in Figure 4.
It is an A-line sectional view. DESCRIPTION OF SYMBOLS 1... Casing, 2... Inlet, 3... Outlet, 4, 5... Monolith catalyst, 8... Secondary air supply nozzle, 10... Hole, 12... Secondary air supply pipe, 20... ...Boss part, 21, 23...Flange,
24...gasket, 25...bolt, 30...
Boss club, 31...Natsuto.

Claims (1)

[Scope of utility model registration request] A plurality of monolithic catalysts are arranged in series in the axial direction of the casing at a predetermined interval in a cylindrical casing equipped with an exhaust gas inlet and an exhaust outlet at the front and rear, and secondary air is introduced in a direction across the interval. In a monolithic catalytic converter with a supply nozzle,
A cylindrical boss member with a flange formed on one side,
One side of the flange is fixed so as to come into contact with the casing wall that maintains the distance, the nozzle is fixed to the side of the boss member that protrudes into the casing, and the nozzle is fixed to the side of the boss member that protrudes outside the casing. A monolithic catalytic converter characterized in that a secondary air supply pipe is detachably attached.