JP3955114B2 - Catalytic exhaust system for internal combustion engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a catalytic exhaust system for an internal combustion engine, for example.
[0002]
[Prior art]
Conventionally, it has been widely adopted to install a catalyst on the muffler as an exhaust purification measure, but in order to mute the muffler and purify the exhaust gas with the catalyst, it is required to allow the exhaust gas to pass through the entire catalyst. Is done.
[0003]
FIG. 2 shows a conventional catalytic exhaust system for an internal combustion engine. In this catalytic exhaust system, exhaust gas introduced from the exhaust pipe of the engine enters the muffler through the inlet pipe 1, and a part of the exhaust gas remains as it is. The exhaust gas flows into the catalyst 4 from the outlet 3 of the inlet pipe 1, and other exhaust gas enters the expansion chamber 6 through the small holes 5 provided in the inlet pipe 1, passes through the discharge port 8 of the isolation wall 7, and enters the catalyst 4. It reaches. The exhaust gas purified by the catalyst 4 enters the expansion chamber 11 through the small hole 10 on the upstream side of the outlet pipe 9, and is discharged from the outlet 13 of the outlet pipe 9 through the small hole 12 on the downstream side of the outlet pipe 9.
[0004]
[Problems to be solved by the invention]
However, in the catalytic exhaust system for an internal combustion engine having the above-described configuration, the flow path becomes complicated because exhaust gas flows through the entire catalyst, and the exhaust resistance may increase and the engine output may decrease. For this reason, it is conceivable to increase the size of the muffler to increase the catalyst and reduce the exhaust resistance. However, in this case, a large amount of expensive catalyst is required, resulting in a high cost.
[0005]
The present invention solves the above problems, and its object is to reduce the exhaust resistance of the muffler, increase the silencing effect, and improve the exhaust gas purification efficiency by allowing the exhaust gas to flow through the entire catalyst. It is an object of the present invention to provide a catalytic exhaust device for an internal combustion engine.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a muffler connected to an exhaust pipe of an engine, an inlet pipe and an outlet pipe are provided in the muffler, and a plurality of partition walls are provided in order from the exhaust upstream side to the resonance chamber and the exhaust purification a catalyst catalytic exhaust system for an internal combustion engine formed by partitioning the catalyst storage chamber and muffling chamber mounted, the inlet pipe to the small diameter portion of the resonance chamber of the partition wall leading to the catalyst storage chamber as a substantially conical shape The catalyst storage chamber is provided in connection with the large diameter portion of the partition wall, and a small hole is provided in the inclined portion of the partition wall so as to partition the catalyst storage chamber and the silencing chamber. A downstream partition is provided. The downstream partition is connected to the outlet pipe at the center thereof to block the upstream end of the outlet pipe, and a plurality of introduction pipes for the sound deadening chamber are arranged around the outlet pipe. The upstream end of the introduction pipe is A support plate is provided which communicates with the catalyst storage chamber through the downstream partition wall, and further closes the downstream end of the introduction pipe in the silencer chamber and has the outlet pipe inserted in the center thereof. The introduction pipe is provided with a small hole in a region sandwiched between the downstream partition wall and the support plate, and the outlet pipe has an inlet port in a region sandwiched between the downstream partition wall and the support plate. Is provided .
Further, in the catalytic exhaust system for an internal combustion engine according to claim 1 , a sound absorbing port is provided in a region sandwiched between the support plate and the downstream end face of the muffler on the tube wall of the outlet pipe. It is preferable.
Further, in the catalytic exhaust system for an internal combustion engine according to claim 2 , a sound absorbing material is disposed around the sound absorbing port, and the sound absorbing material is held by a holding tube on the outer periphery thereof. preferable.
[0007]
According to the catalytic exhaust system for an internal combustion engine having the above-described configuration, the exhaust gas introduced into the muffler from the exhaust pipe of the engine through the inlet pipe flows through the conical isolation wall. The exhaust gas spreads in the shape and flows toward the entire catalyst. And since the introduction pipe of the above-mentioned silencer chamber is arranged around the outer periphery of the downstream side of the catalyst housing chamber, the exhaust gas is easily guided to the outer peripheral surface of the catalyst, so that the exhaust gas flows evenly over the entire surface of the catalyst and is purified. Efficiency can be improved. The exhaust gas that has passed through the catalyst housing chamber is introduced into the introduction pipe and reaches the muffler muffler chamber. In this silencer chamber, the exhaust gas introduced into the introduction pipe passes through a small hole provided in the introduction pipe, passes through an inlet provided in the exit pipe, and exits from the introduction pipe to the center side thereof. Then, it passes through the outlet pipe and is discharged out of the muffler. Since the exhaust gas is muffled when passing through the small hole of the introduction pipe and the inlet of the outlet pipe, the silencing effect is superior to that of the prior art.
Further, when the sound absorption port is provided on the tube wall of the outlet pipe, the noise of the exhaust gas is also silenced by the sound absorption port, so that a more excellent noise reduction effect can be achieved.
Furthermore, when a sound absorbing material is disposed around the sound absorbing port and the sound absorbing material is held by the outer peripheral holding tube, the noise of the exhaust gas is absorbed not only by the sound absorbing port but also by the sound absorbing material. An even better sound deadening effect is achieved.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings using preferred examples. FIG. 1 is an assembly sectional view of a catalytic exhaust system for an internal combustion engine according to the present invention. In the figure, the reference numerals are assigned independently of FIG. 2, and the same reference numerals in both figures do not indicate the same parts. In the figure, a muffler 10 connected to an exhaust pipe of an engine (not shown) has both ends of a cylindrical casing 11 closed with disks 12 and 13, and an inlet pipe 15 having a flange 14 is provided on the disk 12. . The inside of the casing 11 is partitioned into three chambers of a resonance chamber 16, a catalyst storage chamber 17, and a silencer chamber 18 in order from the upstream side. The resonance chamber 16, the catalyst storage chamber 17, and the silencer chamber 18 are partitioned by partition walls 19a and 19b. A partition wall 19a in the resonance chamber 16 reaching the catalyst housing chamber 17 has a conical shape, a small diameter portion 20 of the partition wall 19a is connected to the inlet pipe 15, and a small hole 22 is appropriately provided in the inclined portion 21. .
[0009]
In the catalyst storage chamber 17, catalyst holders 24 and 25 are attached to the casing 11 on the front and rear sides, and a catalyst 27 is held via a cushion material 26.
[0010]
A partition wall 19b is attached to the casing 11 downstream of the catalyst housing chamber 17, and about 3 to 5 introduction pipes 29 having small holes 28 in the silencer chamber 18 are provided around the inner periphery of the casing 11 of the partition wall 19b. And supported by a support plate 30 at the rear of the introduction tube 29. An outlet pipe 33 having an inlet 31 and a sound absorbing port 32 is provided at the center of the introduction pipe 29 and is connected to the disk 13 of the casing 11, and a sound absorbing material 34 is disposed around the sound absorbing port 32. And is held by a holding tube 35 on the outer periphery thereof.
[0011]
In the catalytic exhaust system configured as described above, the exhaust gas introduced from the inlet pipe 15 is silenced between the resonance chamber 16 and the small hole 22 provided in the inclined portion 21 of the partition wall 19a to form a conical shape. The inside of the partition wall 19a is spread without flowing and reaches almost the entire surface of the catalyst 27 . Although a lot of exhaust gas still flows near the center in the partition wall 19a, the exhaust pipe 29 of the muffler chamber 18 on the outlet side of the catalyst 27 is disposed in the vicinity of the outer peripheral surface. Is guided and can flow evenly over the entire surface of the catalyst 27 . Further , since the flow in the muffler chamber 18 forms a simple flow, it is possible to prevent the increase in resistance and obtain a muffler effect by expansion and sound absorption effect.
[0012]
【The invention's effect】
As described in detail above with reference to the embodiment, the catalytic exhaust system for an internal combustion engine according to the present invention has a conical shape by exhaust gas introduced from the inlet pipe being silenced by the small hole in the inclined portion of the partition wall in the resonance chamber. The formed partition wall spreads and flows without resistance, reaching almost the entire surface of the catalyst . Furthermore, in the silencer chamber on the outlet side of the catalyst, exhaust gas is guided into the introduction pipe arranged near the outer peripheral surface of the muffler, so that exhaust gas can flow evenly over the entire surface of the catalyst, and exhaust gas purification efficiency is improved. . Moreover, since the flow in the muffler chamber forms a simple flow, there is an effect of preventing an increase in resistance.
[Brief description of the drawings]
FIG. 1 is an overall sectional view showing a catalytic exhaust system for an internal combustion engine according to the present invention.
FIG. 2 is an overall cross-sectional view showing a catalytic exhaust device for a conventional internal combustion engine.
[Explanation of symbols]
11 Casing 15 Inlet pipe 16 Resonance chamber 18 Silence chamber 19a Partition wall 29 Introducing tube

Claims (3)

A muffler is connected to the exhaust pipe of the engine, an inlet pipe and an outlet pipe are provided in the muffler, and a resonance chamber, a catalyst storage chamber and a silencer chamber in which a catalyst for exhaust purification is mounted in order from the exhaust upstream side by a plurality of partition walls A catalytic exhaust system for an internal combustion engine divided into
With connecting the inlet tube to the small diameter portion as a substantially conical resonance chamber partition wall leading to the catalyst storage chamber, said catalyst storage chamber is arranged in connection with the large-diameter portion of the partition wall, the inclined portion of the further partition wall There is a small hole in the
A downstream partition is provided so as to partition the catalyst housing chamber and the silencing chamber, and the downstream partition is connected to the outlet pipe at the center thereof to block the upstream end of the outlet pipe, and A plurality of introduction pipes of the silencing chamber are arranged around the outlet pipe, and one upstream end of the introduction pipe communicates with the catalyst storage chamber via the downstream partition ,
Further, the silencer chamber is provided with a support plate that closes one end of the downstream side of the introduction pipe and the outlet pipe is inserted through the center thereof, and the introduction pipe includes the downstream partition wall and the support plate. A small hole is provided in a region sandwiched between the two, and the outlet pipe is provided with an inflow port in a region sandwiched between the downstream partition wall and the support plate. Exhaust system. The catalytic exhaust system for an internal combustion engine according to claim 1,
A catalytic exhaust system for an internal combustion engine, characterized in that a sound absorption port is provided in a region sandwiched between the support plate and a downstream end face of the muffler on a tube wall of the outlet tube . The catalytic exhaust system for an internal combustion engine according to claim 2,
A catalytic exhaust system for an internal combustion engine , wherein a sound absorbing material is disposed around the sound absorbing port, and the sound absorbing material is held by a holding tube on the outer periphery thereof .

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