JPH0558817U - Exhaust gas purification / silencer for air-fuel mixture engines - Google Patents

Abstract

(57) [Abstract] [Purpose] An oxidation catalyst is housed in the muffler of the engine to prevent secondary air from flowing back into the cylinder chamber with a simple structure, while reducing the size of the exhaust gas purifying / silencer device. Miniaturize the outer shape of the engine. [Structure] A catalyst chamber 9 is formed in the muffler main body 7 of the muffler downstream of the primary silencing chamber 8, and the oxidation catalyst 3 is formed in the catalyst chamber 9.
To house. The exhaust inlet hole 10 and the outlet 11 of the secondary air supply passage 6 are opened so as to face the primary silencing chamber 8, and the outlet 11 of the secondary air supply passage 6 and its exhaust inlet hole are opened in the primary silencing chamber 8. A secondary air suction prevention plate 12 is interposed between the secondary air suction plate 10 and the secondary air suction plate 10. With this secondary air suction prevention plate 12,
Due to the pulsation of exhaust pressure, the secondary air is discharged from the outlet 1 of the secondary air supply passage 6.
It is prevented from being short-circuited from 1 to the exhaust inlet hole 10 and being sucked out.

Description

[Detailed description of the device]

[0001]

[Industrial application]

 The present invention relates to a device for purifying and muffling exhaust gas of a mixture intake type engine.

[0002]

[Prior Art]

 2. Description of the Related Art Some conventional exhaust gas purification / silencer devices for air-fuel mixture intake engines are configured as shown in FIG. 4, for example. That is, the catalyst case 20 containing the exhaust gas purification oxidation catalyst 3 is connected to the exhaust port 2 of the air-fuel mixture intake engine 1 via the exhaust gas flow path 5, and the muffler 4 is connected to the gas outlet 21 of the catalyst case 20. To communicate. The outlet 11 of the secondary air supply passage 6 for purifying exhaust gas is opened in the exhaust gas passage 5. The inlet 6a of the secondary air supply passage 6 opens into the air purifying chamber 24 of the air cleaner 22, and a check valve 25 and a flow control valve 26 are provided in the middle of the inlet 6a. The flow rate control valve 26 detects the intake negative pressure of the intake pipe 23 to control the supply amount of the secondary air to an amount commensurate with the amount of the exhaust gas.

[0003]

[Problems to be solved by the device]

 The above conventional technique has the following problems. (A) Since the gas outlet 21 of the catalyst case 20 is communicated with the muffler 4, a catalyst case, a catalyst case pipe joint, a catalyst case support device, etc. are required, which complicates the structure. (B) Since the catalyst case 20 and the muffler 4 are connected in series from the engine body, the exhaust purification / silencer device becomes large, and the engine outer shape becomes large. (C) Secondary air is sucked into the exhaust gas flow passage 5 from the secondary air supply passage 6 in the negative pressure portion of the pressure pulsation of the engine exhaust. This negative pressure portion is generated by the suction force of the cylinder chamber when the intake and exhaust valves overlap at the same time. In this negative pressure portion, a large amount of the secondary air sucked from the secondary air supply passage 6 into the exhaust gas passage 5 is smoothly sucked into the cylinder chamber. Therefore, the mixture concentration of the air-fuel mixture is diluted from the appropriate concentration, combustion failure occurs, and the amount of HC / CO generated in the cylinder chamber increases. The present invention has two objectives: (a) simplifies the structure of the exhaust gas purification / silencer of an air-fuel mixture engine, (b) downsizes the purification / silencer, and (c) simplifies the structure. The problem is to reduce the reverse flow rate of secondary air to the cylinder chamber.

[0004]

[Means for Solving the Problems]

 In order to achieve the above-mentioned object, the present invention is characterized by being configured as follows, for example, as shown in FIGS. That is, in the muffler body 7 of the muffler 4, a catalyst chamber 9 is formed on the downstream side of the primary silencing chamber 8, and the oxidation catalyst 3 is accommodated in the catalyst chamber 9. Further, the exhaust inlet hole 10 and the outlet 11 of the secondary air supply passage 6 are opened so as to face the primary silencing chamber 8, and the outlet 11 of the secondary air supply passage 6 is opened in the primary silencing chamber 8. The secondary air suction prevention plate 12 is interposed between the exhaust air inlet hole 10 and the exhaust air inlet hole 10. Then, in the primary muffling chamber 8, the secondary air supplied from the outlet 11 of the secondary air supply path 6 is short-circuited to the exhaust inlet hole 10 and is sucked out due to the pulsation of the exhaust pressure. The secondary air suction prevention plate 12 is used for prevention.

[0005]

[Action]

 The present invention works as follows. In the negative pressure portion of the pressure pulsation of the exhaust gas of the engine 1, secondary air is sucked into the primary silencing chamber 8 of the muffler 4 from the outlet 11 of the secondary air supply passage 6. This secondary air is diverted by the secondary air suction prevention plate 12 and reaches the exhaust inlet hole 10 after being given ventilation resistance, so that the amount of backflow to the cylinder chamber is greatly reduced. As a result, the degree to which the air-fuel mixture with the proper concentration in the cylinder chamber is diluted by the mixing of the secondary air and becomes difficult to burn is greatly reduced, and the amount of HC / CO generated in the cylinder chamber is reduced.

[0006]

[Effect of the device]

 The present invention has the following effects because it is configured and operates as described above. (A) Since the oxidation catalyst 3 is housed in the muffler body 7, the catalyst case, the pipe joint of the catalyst case, the catalyst case supporting device, etc. can be omitted, and the structure is simplified. (B) Since the catalyst case and the pipe joint of the catalyst case are omitted, the exhaust gas purification / silencer device is downsized, and the outer shape of the engine can be downsized. (C) At the time of overlap when the intake and exhaust valves of the engine are open at the same time, the secondary air flows from the secondary air supply passage 6 to the exhaust gas passage 5 in the negative pressure portion of the exhaust pressure generated by the suction force of the cylinder chamber. It is prevented by the secondary air suction prevention plate 12 in the primary muffler chamber 8 that the air is sucked in. As a result, the mixture concentration of the air-fuel mixture is diluted from the proper concentration, combustion failure is caused, and the amount of HC / CO generated in the cylinder chamber is reduced.

[0007]

【Example】

 Embodiments of the present invention will be described below with reference to the drawings. 1A is a vertical cross-sectional view of the muffler body, FIG. 1B is a cross-sectional view taken along the line X-X of FIG. 1A, and FIG. 1C is a line Y-Y of FIG. 1A. FIG. 2 is a sectional view taken in the direction of the arrow, FIG. 2 is a plan view of the air-fuel mixture intake engine, and FIG. 3 is a rear view of the same. In the figure, a muffler 4 is communicated with an exhaust port 2 of an air-fuel mixture intake engine 1 via an exhaust gas passage 5. The muffler inlet pipe 13 of the exhaust gas flow path 5 is connected to the primary muffler chamber 8 in the muffler body 7 of the muffler 4, and the secondary muffler chamber 14, the catalyst chamber 9, the third muffler chamber 15 and the muffler outlet are provided downstream thereof. The pipe 16 is formed so as to communicate with each other in order. Further, the secondary air supply passage 6 for purifying the exhaust gas is connected to the primary muffling chamber 8 from the air cleaner 22 via a flow rate control valve 24 controlled by the intake negative pressure of the intake pipe 23. Exhaust gas introduction pipes 14a, 14b, 14c are provided between the primary silencing chamber 8 and the secondary silencing chamber 14, and a barrier 14d and exhaust outlet holes 14e, 14f, ... Are provided in the secondary silencing chamber 14. Is provided. Then, the oxidation catalyst 3 is housed in the catalyst chamber 9, faces the primary silencing chamber 8, and the exhaust inlet hole 10 of the muffler inlet pipe 13 and the outlet 11 of the secondary air supply passage 6 are opened. .. Further, in the primary muffling chamber 8, a secondary air suction prevention plate 12 is interposed between the outlet 11 of the secondary air supply passage 6 and the exhaust inlet hole 10. The secondary air sucking-out prevention plate 12 allows the secondary air supplied from the outlet 11 of the secondary air supply passage 6 in the primary muffling chamber 8 to be discharged through the exhaust air inlet hole due to the pulsation of the exhaust pressure. It is configured to prevent short circuit to 10 and sucking out.

[Brief description of drawings]

1 shows an embodiment of the present invention, FIG. 1 (A) is a vertical sectional view of a muffler body, FIG. 1 (B) is a sectional view taken along the line XX of FIG. 1 (A), and FIG. 1 (C). FIG. 2 is a sectional view taken along the line YY of FIG.

FIG. 2 is a plan view of the air-fuel mixture intake engine according to the embodiment of the present invention.

FIG. 3 is a rear view of the air-fuel mixture intake engine according to the embodiment of the present invention.

FIG. 4 is a cross-sectional view of a main part of a mixture intake type engine showing a conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Air-fuel mixture intake engine, 2 ... Exhaust port, 3 ... Oxidation catalyst, 4 ... Muffler, 5 ... Exhaust gas flow passage, 6 ... Secondary air supply passage, 7 ... Muffler main body, 8 ... Primary silencing chamber, 9 ... Catalyst chamber,
10 ... Exhaust inlet hole, 11 ... Exit, 12 ... Secondary air suction prevention plate.

Claims (1)

[Scope of utility model registration request] 1. An exhaust port of a mixture intake engine (1)
The oxidation catalyst (3) and the muffler (4) are communicated with (2), and a secondary air supply passage (6) for purifying exhaust gas is provided in the exhaust gas flow path (5) upstream of the oxidation catalyst (3). ) Are communicated with each other, the exhaust gas purifying / silencing device for a mixture intake type engine is provided with a primary silencing chamber (8) in the muffler body (7) of the muffler (4).
A catalyst chamber (9) is formed on the further downstream side, the oxidation catalyst (3) is housed in the catalyst chamber (9), and it faces the primary silencing chamber (8), and the exhaust inlet hole (10) and the The outlet (11) of the secondary air supply passage (6) is opened, and the outlet (1) of the secondary air supply passage (6) is opened in the primary silencing chamber (8).
A secondary air suction preventive plate (12) is interposed between 1) and the exhaust inlet hole (10), and the secondary air supply passage ( The secondary air supplied from the outlet (11) of 6) is short-circuited to the exhaust inlet hole (10) and sucked out.
A device for purifying and silencing exhaust gas of an air-fuel mixture intake engine, characterized in that the secondary air suction prevention plate (12) is used for prevention.