JP2000018031A - Exhaust emission control device for general internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate handling without directly interfering a part for leading secondary air toward an exhaust port with an outer part as well as surely and easily arranging a device regardless of arrangement and shape of an auxiliary machine of a general internal combustion engine. SOLUTION: A secondary air leading part SAS is arranged to lead secondary air to an exhaust port 9c of a general internal combustion engine. The secondary air leading part SAS is formed on a cylinder head cover 10. The secondary air leading part SAS is provided with an air circulating passage R which is formed on a cylinder head cover 10 and communicated with an exhaust port 9c of the cylinder head 10, a filter for cleaning air which is arranged in the air circulating passage R, and a secondary air valve 18 which is arranged downstream from the filter in the air circulating passage R, which is opened/closed in association with pulsation of pressure generated in an exhaust port 9c, and arranged for circulating and shutting out the air circulating passage R.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas purifying apparatus for a general purpose internal combustion engine, and more particularly to an exhaust gas purifying apparatus for purifying exhaust gas by supplying secondary air to an exhaust port of a general purpose internal combustion engine. .

[0002]

2. Description of the Related Art A general-purpose internal combustion engine is used as a driving source for various things, such as a portable generator, and the general-purpose internal combustion engine is currently required to take measures for purifying exhaust gas. . For this reason, secondary air is supplied to an exhaust port of the internal combustion engine, oxygen is supplied to exhaust gas discharged from the internal combustion engine, and harmful components contained in the exhaust gas, for example, H
An apparatus is provided for removing harmful gases by oxidizing (secondary combustion) of C, CO and the like.

As described above, as an exhaust gas purifying device for supplying secondary air to an exhaust port of a general-purpose internal combustion engine, an exhaust port is connected to an air cleaner for supplying clean air to a carburetor through a ventilation pipe or the like. Connecting and supplying clean air from the air cleaner as secondary air,
Alternatively, an air cleaner dedicated to the secondary air (hereinafter referred to as a secondary air cleaner) is provided separately from an air cleaner connected to the carburetor as described above (hereinafter referred to as a carburetor-side air cleaner). The secondary air cleaner connected to an exhaust port via a ventilation pipe or the like is generally known at present.

[0004]

However, in the above-mentioned conventional air purifying apparatus for a general-purpose internal combustion engine, the carburetor-side air cleaner or the secondary air cleaner and the exhaust port are connected by a ventilation pipe. Therefore, when used, the ventilation pipe may be caught by surrounding members or a user, and the ventilation pipe or the surrounding members may be damaged. Further, when connecting the exhaust port to the engine-side air cleaner, there is a problem that the length and piping of the ventilation pipe are greatly affected by the arrangement and shape of the auxiliary equipment such as the air cleaner and the carburetor. When installing the secondary air cleaner, in addition to its own arrangement, the piping of the ventilation pipe, etc.
There is a problem that it is difficult and complicated to design and manufacture because of being affected by the configuration and the like.

The present invention has been made in view of the above-mentioned problems of the prior art, and can be installed reliably and easily without being affected by the arrangement and shape of accessories of a general-purpose internal combustion engine. An object of the present invention is to provide a purifying apparatus for a general-purpose internal combustion engine, in which a connecting portion between a port and a secondary air cleaner does not directly interfere with an external one during transportation or use, and is easy to handle.

[0006]

The present invention has the following arrangement to solve the above-mentioned problems. That is, according to the present invention, a cylinder head cover is provided at an outer end portion of a cylinder head fixed to a crankcase via a cylinder, and exhaust gas in the cylinder head is supplied to a predetermined exhaust path from an exhaust port formed in the cylinder head. An exhaust gas purifying apparatus provided with a secondary air introduction unit for introducing secondary air to the exhaust port for a general-purpose internal combustion engine that discharges air to the cylinder head cover. And an air circulation path communicating with the exhaust port of the cylinder head, an air purification filter disposed in the air circulation path, and a downstream side of the air filtration filter in the air circulation path. Placed,
Open and close with the pulsation of pressure generated in the exhaust port,
And a secondary air valve for communicating and shutting off the air flow path.

In the present invention having the above structure, positive and negative pressure fluctuations (pulsations) occur in the exhaust port due to driving of the general-purpose internal combustion engine, and when the exhaust port has a negative pressure, the secondary air valve is opened. Since the air circulation path communicates with the exhaust port, clean secondary air filtered through the filter flows into the exhaust port, and the exhaust gas is oxidized.
Air purification is performed. Here, since the secondary air introduction unit having the air circulation path, the filter, and the secondary air valve is provided on the cylinder head cover fixed to the upper end of the cylinder head, the cylinder head cover is mounted on the cylinder head. At the same time, attachment to the internal combustion engine can be completed, and no special attachment work is required, so that manufacture and maintenance can be easily performed. In addition, since the air introduction path and other components that make up the air introduction section are not exposed to the external space at all, the medium secondary air introduction section may directly interfere with surrounding members during use or transportation. Not easy to handle.

Further, if the air suction port of the air flow path is formed at a position separated from the exhaust port in the exhaust path, the air in the atmosphere heated to a high temperature by the exhaust from the exhaust port is not sucked. Since a low-temperature and high-density air is sucked in a portion separated from the air, good oxidizing action can be performed.

Further, as a cylinder head cover,
A cover body fixed to the outer end of the cylinder head,
A cover fixed to the outer end portion of the cover main body in a detachable function, wherein the cover main body has an intake path formed with an intake port for introducing outside air, and a downstream side communicating with an exhaust port of a cylinder head. A cover that covers a downstream opening of the intake passage; and an upstream connection passage that guides clean air that has passed through the filter to the downstream connection passage. It is possible.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings with reference to FIGS. 1 is a left side view showing a general-purpose internal combustion engine according to an embodiment of the present invention, FIG. 2 is a right side view of the one shown in FIG. 1, FIG. 3 is a front view of the one shown in FIG. 2, and FIG. FIG. 5 is a side view showing the cylinder head cover viewed from the direction indicated by the arrow P of FIG. 1, FIG. 5 is a sectional view taken along line XX of FIG. 1 and FIG.
7 is a cross-sectional view taken along the line YY of FIG. 4, FIG. 7 is a cross-sectional view taken along the line ZZ of FIG. 4, and FIG.
FIG. 9 is a view from the direction of arrow B in FIG.

1 to 3, a general-purpose internal combustion engine E
Are an internal combustion engine main body 1, a fuel tank 2 provided above the internal combustion engine main body 1, an air cleaner (a carburetor-side air cleaner) 3 disposed on the right side of the internal combustion engine main body 1, A carburetor 4 that mixes clean air supplied from a cleaner 3 and fuel supplied from the fuel tank 2 and supplies the mixed gas to the internal combustion engine main body 1 and an exhaust gas generated in the internal combustion engine main body 1 An exhaust pipe 5 leading to the outside and a muffler 6 and the like connected to the exhaust pipe 5 are mainly provided. The internal combustion engine body 1 includes a cylinder 8 that movably stores a piston in a crankcase 7 that rotatably supports a crankshaft 7a.
The cylinder head 9 projects diagonally forward, and a cylinder head cover 10 is fixed to an outer end of the cylinder head 9.

The crankshaft 7a has a fan cover 13 fixed to the right side of the crankcase 7.
(Not shown), recoil starter 14 located outside thereof, and the like are attached.
Pull the starter lever 14a of the recoil starter 14,
By forcibly rotating the crankshaft 7a, the spark plug 9P provided in the cylinder head 9 is ignited, the internal combustion engine main body 1 is driven, and the crankshaft 7a rotates with the reciprocation of the piston. Has become.

Here, the cylinder head cover 10
Is configured as shown in FIGS. The cylinder head cover 10 shown here is
The head cover main body 11 is fixed to the outer end of the head cover 11 and the lid 12 is fixed to the outer end of the head cover main body 11. The cylinder head 7 has
As shown in FIG. 5, an exhaust port 9c is formed so as to communicate with an exhaust port 9b opened and closed by an exhaust valve 9a, and an exhaust pipe 5 forming an exhaust passage together with the muffler 6 is connected to the exhaust port 9c. Have been. In the exhaust port 9c, a fifth air passage W5 parallel to the axial direction of the cylinder 8 is formed in a thick portion of the side wall 91 of the cylinder head 9.

The head cover body 11 is fastened and fixed to the outer end of the cylinder head 9 by bolts B11 (see FIG. 4). Inside the head cover body 11, as shown in FIGS. The first air chamber R1, the first air passage W1, and the air breather chamber R10 are defined and the fourth air chamber R4, the third and fourth air passages W3 and W4 are defined as shown in FIG. Have been. The downstream end of the fourth air passage R4 communicates with the upstream end of a fifth air passage W5 formed in the cylinder head 9, and the upstream end of the fourth air passage R4 is connected to the fourth air passage R4. It is connected to the third air chamber R3. The first and fourth air chambers R1 and R4 have a concave shape whose upper end is open, as shown in FIGS. In addition, the breather chamber R1
0 is a vaporizer side air cleaner 3 by a connecting pipe (not shown).
It is connected to. The first air passage W1 and the first air chamber R1 form an intake passage, the third and fourth air passages W3, W4, and the fourth air chamber R4 form a downstream air passage, and the second air passage R2 forms a second air passage R2. An upstream air passage is formed by each of the second and third air chambers R2 and R3.

On the other hand, the lid 12 is fixed to the cylinder head cover 11 by bolts B12. Then, inside the lid 12, two second air chambers R2,
A second air passage W2 located between R2 and both air chambers R2 and R2 and communicating with both air chambers R2 and R2;
A third air chamber R3 communicating with the air passage W2 is formed, and the lower ends of the air chambers R2 and R3 are open downward. An air filtering filter 15 made of sponge or the like is provided in the opening of the second air chamber R2.
The filter 15 also fits and fixes the opening of the first air chamber R1 formed in the head cover main body 11 by the filter 15. The filter 1
5 has an intermediate portion supported by a rib R1a provided inside the first air chamber R1.

At one end of the opening of the third air chamber R3, one end of a secondary air valve 18 formed of an elastic plate is fixed in a cantilever spring manner by a screw 18a. The opening of the third air chamber R3 is kept closed. The opening of the third air chamber R <b> 3 has a fourth cover formed in the head cover main body 11.
The opening of the air chamber R4 is opposed to surround the opening of the third air chamber R3, and the secondary air valve 18 is in the open state (from the opening of the third air chamber R3 to the secondary air valve 1).
8 is in the separated state), the two air chambers R3, R4 communicate with each other. As described above, the air circulation path R is formed by the first to fifth air passages W1 to W5 and the air chambers R1 to R4.
The filter 15 and the secondary air valve 18 form a secondary air introduction portion SAS. In FIG. 5, 9
Reference numerals d and 11d denote rocker arm chambers formed in the cylinder head 9, in which well-known valve driving mechanisms (not shown) including the rocker arm are housed.

In the general-purpose internal combustion engine of this embodiment configured as described above, the recoil starter 1
When the starter lever 14a is pulled and the internal combustion engine main body 1 is driven, the pressure at the exhaust port 9c of the internal combustion engine main body 1 pulsates in accordance with a series of driving cycles, and negative pressure and positive pressure are generated alternately. When the exhaust port 9c has a positive pressure, the secondary air valve 18 is closed, the communication between the third air chamber R3 and the fourth air chamber R4 is cut off, and the secondary The supply of air is also shut off.
When the pressure in the crankcase 7 becomes positive, the breather control valve is opened, and air is discharged from the breather chamber R10 to the outside, so that the pressure in the crankcase 7 is maintained at a negative pressure. It has become.

When the exhaust port 9c has a negative pressure, the secondary air valve 18 is opened and the air chamber R3 is opened.
And the air chamber R4 communicate with each other, so that the air circulation path R is in a communicating state. For this reason, the outside air introduced from the intake port of the first air passage passes through the filter 15 from the first air chamber R1, where dust and the like are removed to become clean secondary air, which is formed on the lid 12. It flows into the second air chamber R2.
The secondary air that has flowed into the second air chamber R2 passes through the passage W2.
Flows into the third air chamber R3 through the second air valve 18, and then through the opened secondary air valve 18, the air chamber R4, the third air passage W3, the fourth air passage W4, and the fifth air passage W5 sequentially. It flows and flows into the exhaust port 9c. As a result, the oxidation of the exhaust gas is promoted by the secondary air flowing into the exhaust port 9c, and harmful components are removed and the purified exhaust is discharged from the muffler 6.

By this exhaust gas, an atmosphere having a relatively high temperature is formed in the vicinity of the muffler 6 and in the outflow range of the exhaust gas as compared with other spaces, but the intake port W1a of the first air passage W1 is The air outlet W1a of the first air passage W1 is separated from the exhaust port of the muffler 6 on the opposite side to the exhaust flow direction and is not located in the high temperature atmosphere.
, Air having a relatively low temperature which is not affected by the exhaust gas is sucked. For this reason, the air sucked from the suction port W1a becomes high-density, large-mass air, and
Sufficient oxygen is supplied to c, and a good oxidation function can be obtained.

In the above-described embodiment, the secondary air introduction portion SAS having the air circulation path R, the filter 15, the secondary air valve 18, and the like is integrally accommodated in the cylinder head cover 10. By attaching the cylinder head cover 10 to the cylinder head 9, no pipe is required for mounting the secondary air introduction portion SAS to the internal combustion engine body 1. For this reason, it is not necessary to consider the relationship with peripheral members such as auxiliary equipment, and the operation is simplified, and manufacturing and maintenance are facilitated. In addition, the secondary air introduction section SAS has the air circulation path R and all other parts housed in the cylinder head cover 10 and does not protrude to the outside, so that the secondary air introduction section SAS can be configured compactly and can be used or transported. In such a case, the secondary air introduction portion SAS does not interfere with surrounding members and workers, and is extremely easy to handle.

The cylinder head cover 10 in this embodiment is composed of a cover body 11 and a cover body 12 which can be divided by bolts B12 and the like, and a filter 15 as a cover body and a secondary air valve 18 as a cover body. Since the filter 15 is fixed to each of the filters 11, cleaning and replacement of the filter 15, replacement of the secondary air valve 18, and the like can be easily performed by removing the lid 12. However, the cover body 11 and the lid 12 can be integrated, and the present invention is not particularly limited to the above embodiment.

[0022]

As described above, according to the present invention,
A secondary air introduction part having an air flow path for supplying secondary air to an exhaust port of a general-purpose internal combustion engine, a filter, a secondary air valve, and the like is housed in a cylinder head cover fixed to an upper end of the cylinder head. Therefore, the attachment to the internal combustion engine can be completed simultaneously with the attachment of the cylinder head cover to the cylinder head, and the attachment work can be performed extremely easily, and the production and maintenance can be greatly simplified. Also, the air introduction section
Since the air circulation path and other components constituting this are not exposed to the external space at all, the secondary air introduction part does not directly interfere with the surrounding members even during use or transportation, and it is easy to handle. In addition, there is no possibility that surrounding members may be damaged.

Further, if the air suction port of the air circulation path is formed at a position separated from the exhaust port in the exhaust path, the air in the atmosphere heated to a high temperature by the exhaust from the exhaust port is not sucked, and the exhaust port is not exhausted. Since it is possible to suck the low-temperature and high-density air at a location separated from the exhaust gas, a good oxidizing function can be obtained, and the purification capability of the exhaust gas is greatly improved.

[Brief description of the drawings]

FIG. 1 is a left side view showing a general-purpose internal combustion engine according to an embodiment of the present invention.

FIG. 2 is a right side view of the one shown in FIG.

FIG. 3 is a front view of what is shown in FIG.

FIG. 4 is a side view showing the cylinder head cover viewed from a direction indicated by an arrow P in FIG. 1;

FIG. 5 is a sectional view taken along the line XX of FIG.

FIG. 6 is a sectional view taken along the line YY of FIG.

FIG. 7 is a sectional view taken along the line ZZ of FIG.

FIG. 8 is a diagram viewed from the direction of arrow A in FIG. 7;

FIG. 9 is a diagram viewed from the direction of arrow B in FIG. 7;

[Explanation of symbols]

 E General-purpose internal combustion engine 1 Internal combustion engine main body 5 Exhaust pipe (exhaust) 7 Crankcase 8 Cylinder 9 Cylinder head 9c Exhaust port 10 Cylinder head cover 11 Head cover main body 12 Lid 15 Filter for air purification 18 Secondary air valve SAS Secondary air introduction Part R Air circulation path R1 to R4 First to fourth air chamber W1a Air inlet W1 to W5 First to fifth air passages

Claims (3)

[Claims] A cylinder head cover is provided at an outer end of a cylinder head fixed to a crankcase via a cylinder, and exhaust gas in the cylinder head is transferred from an exhaust port formed in the cylinder head to a predetermined exhaust path. An exhaust gas purifying apparatus provided with a secondary air introduction unit that introduces secondary air into the exhaust port for a general-purpose internal combustion engine that is configured to discharge the secondary air introduction unit, wherein the secondary air introduction unit is provided on the cylinder head cover. An air flow path formed and communicated with an exhaust port of the cylinder head; a filter for air filtration provided in the air flow path; and a filter disposed downstream of the air purification filter in the air flow path. A secondary air valve that opens and closes with the pulsation of pressure generated in the exhaust port and communicates and shuts off the air flow path; An exhaust gas purifying apparatus for a general-purpose internal combustion engine, comprising: 2. The exhaust gas purifying apparatus for a general-purpose internal combustion engine according to claim 1, wherein the air intake port of the air flow path is formed at a position separated from the exhaust port in the exhaust path. 3. The cylinder head cover includes a cover body fixed to an outer end of the cylinder head, and a lid fixed to the outer end of the cover body with a detachable function. An intake passage formed with an intake port to be introduced, and a downstream air passage communicating with an exhaust port of the cylinder head, wherein the lid is provided with a filter covering the exhaust port of the intake passage, and a filter passing through the filter. The exhaust gas purifying apparatus for a general-purpose internal combustion engine according to claim 1, further comprising: an upstream air passage that guides fresh air to the downstream air passage.