JPH0219542Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement of a catalytic muffler device for an internal combustion engine.

Catalysts are used in exhaust systems alone or in combination with exhaust mufflers to purify automobile exhaust gas. As a conventional example of a device based on this combination, the US
P.4050903 (Japanese Patent Publication No. 55-34289) is available, and its outline will be explained with reference to FIGS. 4 to 6.

FIG. 4 is a side sectional view of the device, FIG. 5 is a sectional view taken from FIG. 4, and FIG. 6 is a sectional view taken from FIG. 4. The muffler contact type converter combination device (abbreviated as catalyst muffler) A of this device is a housing B consisting of a cylindrical portion C, a front partition plate D and a rear partition plate E, and is equipped with the following exhaust purification and noise reduction devices. It consists of a combination.

That is, the front bulkhead plate D has a wing G and a bench lily part H.
An exhaust gas inlet pipe F having a suction hole J is installed therein, and a deflector part K is provided on the axis of the exhaust gas inlet pipe F and fixed to a porous partition plate N to form a mixing chamber L. A large number of through holes P are bored in the porous partition plate N, and an interval chamber Q is provided on the downstream side of the porous partition plate N. For example, an elliptical honeycomb catalyst M shown in the sectional view of FIG. , a catalyst holding member T, and an outlet holding member U, and a cavity R is formed between them and the cylindrical portion C. The entrance holding member S has a plurality of small holes n, and the exit side holding member U has a closed end. Further downstream is the 6th
As shown in the figure, an exhaust chamber W is provided, and in the exhaust chamber W, an outlet pipe X having a porous portion Y formed therein is fixed to a cylindrical portion C by a fixing portion Z.

Next, the purifying and silencing effects of the catalyst muffler A will be explained.

Secondary air is sucked in from the plurality of suction holes J by the aspirator action of the vane G provided on the exhaust gas inlet pipe F and the bench lily part H, and is reversed by the deflector part K, so that the exhaust gas and the secondary air are mixed in the mixing chamber L. Mix thoroughly. The mixed gas flows through the holes P of the porous partition plate N.
The mixed gas flows into the spacer Q, passes through the honeycomb catalyst M, and as the temperature rises, the harmful gas is converted into harmless gas and released into the atmosphere from the porous portion Y provided in the exhaust chamber W via the outlet pipe X. be done.

On the other hand, the noise reduction effect is attenuated by the reversing action of the mixed gas by the deflector part K, the expansion and contraction of the gas as it passes through the many holes P of the porous partition plate N, the honeycomb catalyst M, and the porous pipe Y of the outlet pipe X. In addition, the cavity R formed between the honeycomb catalyst M and the cylindrical part C has a plurality of small holes n in the inlet side holding part S, and the outlet side holding member U is the closed end. It acts as a resonator to attenuate noise.

However, in the catalyst muffler M, since the holding member U on the outlet side of the cavity R has a closed end, there is no flow of mixed gas, and the honeycomb catalyst M has only the heat insulating effect of the air layer, which reduces the amount of exhaust gas. During low idling, it is difficult to secure the amount of heat necessary for the reaction of the honeycomb catalyst M, and there is a drawback that effective catalytic action cannot be obtained.

On the other hand, in Japanese Utility Model Application Publication No. 54-103436, two support plates with a large number of small holes are provided in the case outer cylinder, and a honeycomb is inserted between the support plates with an elastic member in the outer cylinder. This figure shows a muffler/exhaust gas purification device having a structure in which a catalytic converter is provided with a catalyst arranged therein, and an outlet side exhaust conduit is attached to a support on the downstream side. This device attempts to eliminate the above-mentioned drawbacks by heating the catalytic converter by returning the exhaust gas that has passed through the catalytic converter to the outside of the catalytic converter through small holes in the support plate, and then letting it flow out from the exhaust pipe on the exit side. It is.

However, this device may not be sufficiently effective. In other words, the exhaust gas that has passed through the catalytic converter flows into the outside of the converter through the small holes in the support plate, but this exhaust gas does not reach the outer periphery of the upstream side of the converter and immediately approaches the small holes in the support plate. This will result in a short cut to the outlet side exhaust pipe provided at the outlet. Further, since the honeycomb-shaped catalyst in the catalytic converter is disposed within the outer cylinder via an elastic member, heat of exhaust gas around the outer periphery of the converter is difficult to be conducted to the honeycomb-shaped catalyst. As a result of these, the temperature rise of the catalytic converter is
This results in extremely insufficient results.

Therefore, an object of the present invention is to provide a device that increases the temperature of the catalyst and improves the purification efficiency while maintaining the silencing effect.

To describe an example, in FIG. 1, a catalyst muffler 30 has a cylindrical case consisting of an outer cylinder wall 1, a front partition plate 2, and a rear partition plate 3, and an exhaust gas inlet pipe is connected to the front partition plate 2. 4 and secondary air intake pipe 1
3 is provided. Inside the case, an intermediate partition plate 11, a shielding wall 12, and a porous partition plate 19 are provided in order from the front partition plate 2. A secondary air inflow chamber 15 is formed between the front partition plate 2 and the intermediate partition plate 11, and a secondary air chamber 14 is formed between the intermediate partition plate 11 and the shielding wall 12. . Exhaust gas inlet pipe 4
forms an inlet conical cylinder 5 that penetrates the front partition plate 2 and tapers toward the downstream side, and the inlet is slightly larger than the outlet of the inlet conical cylinder 5 at a small interval and is directed downstream. An outlet conical tube 6 which is inclined to become larger is disposed coaxially with the shielding wall 12 to form a bench lily portion, and the downstream side of the outlet conical tube 6 forms a mixed gas inlet 7. The partition pipe 9 on the outside of the bench lily portion 8 is inserted between the front partition plate 2, the intermediate partition plate 11, and the shielding wall 12, and is fixed thereto. The secondary air intake pipe 13 penetrates the front partition plate 2 and the intermediate partition plate 11, and the secondary air inflow chamber 15
and the secondary air chamber 14 are communicated with each other through a communication pipe 16. A plurality of suction holes 17 are formed in the partition pipe 9 on the side of the secondary air inflow chamber 15 . This results in
A mixing section 10 is formed inside the case on the front partition plate 2 side. A porous partition plate 19 having a large number of through holes 21 is provided on the downstream side of the shielding wall 12, and an inflow chamber 18 is formed between these. Further, on the downstream side of the porous partition plate 19, a front closed end plate 22 having an opening in the center is provided, and an interval chamber 23 is formed therebetween. Between the front closed end plate 22 and the rear partition plate 3 inside the case is a rear closed end plate 25 having an opening in the center.
and a partition plate 26 into three chambers, a rear chamber 27 is formed between the rear closed end plate 25 and the partition plate 26, and an exhaust chamber 31 is formed between the partition plate 26 and the rear partition plate 3. . A honeycomb catalyst 20 having an oval cross section is disposed in a chamber between the front closed end plate 22 and the rear closed end plate 25. As is well known, the honeycomb catalyst 20 is made by impregnating an oxidation catalyst into a carrier having a large number of pores extending from one side to many directions. Honeycomb catalyst 2
0, the outer periphery of one side is located around the opening of the front closed end plate 22, and the space between them is airtightly sealed, and the outer periphery of the other side is similarly located around the opening of the rear closed end plate 25. The space between them is airtightly sealed. As a result, a substantially annular cavity 28 is formed between the outer periphery of the honeycomb catalyst 20, the outer cylinder wall 1, and the front and rear closed end plates 22, 25. As shown in FIG. 3, the conduit 32 is inserted into the lower left portion of the rear closed end plate 25. As shown in FIG. A plurality of communication holes 29 are formed at the upper right side of the rear closed end plate 25, that is, at positions substantially symmetrical to the conduction pipe 32. Through the communication hole 29, the empty chamber 28 and the rear chamber 27 communicate with each other. The exhaust chamber 31 and the empty chamber 28 communicate with each other through a plurality of conductive pipes 32 passing through the rear closed end plate 25 and the partition plate 26, and an exhaust pipe 33 communicating with the atmosphere is fixed to the exhaust chamber 31 by a holder 34. ing. In addition, as shown in the figure, small holes 35 are formed in the conduction pipe 32 and the discharge pipe 33 as necessary.
is drilled. In this case, the inside of the conduction pipe 32 and the rear chamber 27 communicate with each other, and the inside of the discharge pipe 33 and the exhaust chamber 31 communicate with each other via these small holes 35.

FIG. 2 shows another embodiment of the catalyst muffler 30', which is mounted upstream of the mixed gas inlet 7', ie, at the flange 36. Secondary air is supplied to an exhaust pipe (not shown) using, for example, an air pump, a reed valve device, etc., and the other configurations are the same as those shown in FIG. 1.

Next, to explain the function of the catalyst muffler, the mixing section 10 in FIGS. 1 and 3 has basically the same function as the one in FIG. When the secondary air flows in from the secondary air suction pipe 13 and flows out to the inflow chamber 18, the secondary air from the secondary air suction pipe 13 is introduced through the secondary air chamber 14, the communication pipe 16, and the suction hole 17 by the aspirator action of the bench lily part 8. , forming a gas mixture. The mixed gas passes through the through holes 21 of the porous partition plate 19 from the inlet chamber 18, enters the spacer chamber 23, and flows through the honeycomb catalyst 20. At this time, harmful components in the exhaust gas are rendered harmless by the action of the secondary air and the oxidation catalyst. The exhaust gas then flows into the rear chamber 27, reverses its flow, flows through the circulation hole 29 provided in the rear closed end plate 25, flows into the cavity 28, passes through the outer periphery of the honeycomb catalyst 20, and then passes through the circulation hole 29. It enters a conduction pipe 32 located symmetrically to 29 and reaches an exhaust chamber 31 from there. The exhaust gas in the exhaust chamber 31 is discharged to the atmosphere from the exhaust pipe 33.
Since the detoxification in this process is based on an exothermic reaction by the oxidation catalyst, the temperature of the exhaust gas increases, and naturally the temperature of the exhaust gas increases when it passes through the empty chamber 28.

The noise transmitted by the exhaust gas is attenuated as the exhaust gas is repeatedly expanded and contracted while flowing through the rear chamber 27, the cavity 28, and the conduit pipe 32.

As described above, the present invention allows the exhaust gas heated by the exothermic reaction of the catalyst to directly hit the outer periphery of the honeycomb catalyst, and connects the flow holes and the conductive pipes.
Since they are arranged in almost symmetrical positions, with one side serving as the exhaust gas inlet and the other serving as the outlet, the honeycomb catalyst can be heated extremely efficiently.
Even when the honeycomb catalyst tends to be at a relatively low temperature, such as when an internal combustion engine is idling, it provides an effective detoxification effect while maintaining its silencing function.

[Brief explanation of drawings]

FIG. 1 is a side sectional view of the product of the present invention, FIG. 2 is a side sectional view of another embodiment, and FIG.
Fig. 4 is a side sectional view of the conventional product, Figs. 5 and 6 are - sectional views of Fig. 4,
- shows a cross-sectional view; 3... Rear bulkhead plate, 10... Mixing section, 18...
Inflow chamber, 19... Porous partition plate, 20... Honeycomb catalyst, 23... Spacing chamber, 24... Rear, 26...
Partition plate, 27...rear room, 28...vacant room, 30,3
0'...Catalyst muffler, 31...Exhaust chamber, 32...
... Conduction pipe, 33... Discharge pipe.

Claims (1)

[Scope of utility model registration request] In a cylindrical case consisting of an outer cylinder wall, a front partition plate, and a rear partition plate, a front closed end plate and a rear closed end plate with an opening in the center, and partition plates are arranged at intervals sequentially from the front partition plate. At the same time, an exhaust gas inflow pipe and a secondary air intake pipe are attached to the front bulkhead plate, the space between the front bulkhead plate and the front closed end plate is an inflow chamber, and the front closed end plate and the rear closed end plate are connected to each other. A honeycomb catalyst is disposed by impregnating the formed chamber with an oxidation catalyst, a cavity sealed with the inflow chamber is formed around the outer periphery of the catalyst, and a space between the rear closed end plate and the partition plate is defined as a rear chamber, A communication hole is drilled in the rear closed end plate to communicate the empty chamber with the rear chamber, and a conductive pipe is passed through the rear closed end plate at a position approximately symmetrical to the communication hole to separate the empty chamber from the rear chamber. A catalytic muffler device for an internal combustion engine in which a chamber formed by a plate and a rear bulkhead plate communicates with each other.