JP2000018030A - Exhaust emission control device for general internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent deterioration and carbonization of oil in a rocker arm chamber as well as suppressing a secondary air inlet tube exposed to the outside in a secondary air passage arranged from an exhaust port to an air cleaner. SOLUTION: A secondary air leading-in part is arranged to lead secondary air to an exhaust port 9c of a general internal combustion engine. The secondary air leading-in part is provided with a secondary air passage W formed from an intake port R1a formed along from a cylinder head cover 10 to an exhaust port 9c of a cylinder head 9, a secondary air valve 122 arranged in the secondary air passage W, and a secondary air inlet tube 15 for connecting an intake port R1a of the secondary air passage W and an air cleaner to each other. The secondary air passage W is partitioned and formed outward from rocker arm chambers 9d, 13d by a cylinder head cover 10 and an outer wall part 111 of the cylinder head 9.

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 components by oxidizing (secondary combustion) of C, CO and the like.

As described above, as an exhaust gas purifying apparatus for supplying secondary air to an exhaust port of a general-purpose internal combustion engine, an air cleaner for supplying clean air to a carburetor via a secondary air inlet tube or the like is used. It is generally known that an exhaust port is connected to supply clean air from the air cleaner as secondary air.

[0004]

However, in the above-mentioned conventional air purifying apparatus for a general-purpose internal combustion engine, the secondary air flows along a relatively long path from the air cleaner on the carburetor side to the exhaust port of the cylinder. Since the inlet tube is provided, the ventilation pipe may be caught by surrounding members and users during use, and the ventilation pipe and surrounding members may be damaged, so that care must be taken in handling. there were. Furthermore, when connecting the exhaust port to the engine-side air cleaner, the length and piping of the secondary air inlet tube are greatly affected by the arrangement and shape of auxiliary equipment such as the air cleaner and carburetor. There has been a problem of difficulty and complexity in manufacturing.

[0005] Further, a secondary air inlet tube may be passed through a rocker arm chamber of a cylinder head and connected to an exhaust port to prevent the secondary air inlet tube from being caught by an external member or the like. Proposed. However, the heat of the exhaust gas discharged to the exhaust port is transmitted to the secondary air inlet tube, and this heat is further transmitted to the oil mist in the rocker arm chamber. A problem that occurs.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and minimizes the length of a secondary air inlet tube exposed to the outside in a secondary air passage from an exhaust port to an air cleaner. It is an object of the present invention to provide a purification device for a general-purpose internal combustion engine, which can prevent interference with external components and can prevent deterioration, carbonization, and the like of oil in a rocker arm chamber.

[0007]

The present invention has the following arrangement to solve the above-mentioned problems. That is, claim 1 of the present application
According to the invention described above, a cylinder head cover is provided at an outer end portion of a cylinder head fixed to a crankcase via a cylinder, a rocker arm chamber is formed by the cylinder head and an outer wall of the cylinder head cover, and exhaust in the cylinder head is performed. A general-purpose internal combustion engine that discharges gas from an exhaust port formed in the cylinder head to a predetermined exhaust path, and an exhaust gas provided with a secondary air introduction unit that introduces secondary air into the exhaust port In the purifying apparatus, the secondary air introduction section includes a secondary air passage formed from an intake port formed in the cylinder head cover to an exhaust port of the cylinder head, and a secondary air passage provided in the secondary air passage. A secondary air valve, a secondary air inlet tube connecting the air inlet of the secondary air passage and an air cleaner. The door is provided, the secondary air passage, the outer wall of the cylinder head cover and the cylinder head, is obtained by Ku轄 formed outward from said rocker arm chamber.

According to a second aspect of the present invention, the cylinder head cover includes a rocker arm chamber, a valve storage chamber formed outside the locker arm chamber, and an upstream passage having an upstream end communicating with the valve storage chamber. In addition, the cylinder head includes a rocker arm chamber and a downstream passage formed in the outer wall thereof and communicating with an upstream end of the upstream passage.The valve storage chamber includes a secondary air valve. In addition to the housing, an intake port is formed upstream of the secondary air valve, and a secondary air inlet tube connecting pipe is connected to the intake port.

[0009] The invention described in claim 3 of the present application is the above-described claim 2.
In the described invention, the upstream side passage and the downstream side passage, with respect to the joining surface of the cylinder head and the cylinder head cover,
These are formed by through holes formed linearly in a direction substantially orthogonal to each other. The invention according to claim 4 of the present application is the invention according to claim 2 or 3, wherein a plurality of upstream passages and downstream passages are formed in the cylinder head cover and the cylinder head.

Further, according to a fifth aspect of the present invention, in the second aspect of the present invention, the upstream passage and the downstream passage are formed by casting or machining or a combination of both. is there. Also,
The invention according to claim 6 of the present application is one in which the secondary air inlet tube is disposed in a space surrounded by accessories connected to a general-purpose internal combustion engine body.

According to the first aspect of the present invention having the above structure, the cylinder head and the cylinder head cover form a secondary air passage from the exhaust port to the cylinder head. However, since there is only a short secondary air inlet tube that connects the space from the cylinder head cover to the air cleaner, there is a possibility that the secondary air inlet tube may be caught on an external member during transportation or use. Is extremely low. Also, even if the secondary air passage is overheated by the heat of the exhaust gas discharged to the exhaust port, since the secondary air passage is located outside the rocker arm, the secondary air passage is generated by the oil mist in the rocker arm. The heat of the air passage is not transferred,
Oil deterioration and carbonization do not occur. In addition, since all parts except the secondary air valve are housed in the cylinder head cover and the cylinder head, it is possible to manufacture the apparatus very compactly.

Further, in the invention according to the second aspect of the present invention, since the valve storage chamber is formed in the cylinder head cover and the valve is stored in the valve storage chamber, the mounting of the valve can be performed simultaneously with the mounting and dismounting of the cylinder head cover. Manufacturing, maintenance, and the like become easy. In the invention described in claim 3 of the present application, the upstream passage and the downstream passage are respectively formed by through holes that are linearly formed in a direction substantially orthogonal to the joint surface between the cylinder head and the cylinder head cover. Therefore, the upper and lower passages can be easily formed. In particular, when the passage is formed by a mold in the casting of the cylinder head and the cylinder head cover, good releasability can be obtained, and the production becomes easy.

Further, since the flow rate of the secondary air depends on the opening area of the secondary air circulation path, a plurality of upstream passages and downstream passages are formed as in the invention according to the fourth aspect of the present invention. It is possible to accurately control the flow rate of the secondary air by the number thereof, and furthermore, it is possible to form the upstream passage and the downstream passage by using either casting or machining, It is also possible to form a minimum secondary air passage by casting and increase the number of secondary air passages by machining if necessary. Furthermore, according to the invention as set forth in claim 6 of the present application, since the secondary air inlet tube is surrounded by the auxiliary equipment, even if the secondary air inlet tube is in the outside, there is no inconvenience that the secondary air inlet tube is caught outside, and the handling is extremely small. It will be easy.

[0014]

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 the general-purpose internal combustion engine according to the embodiment of the present invention, FIG. 2 is a right side view of the one shown in FIG. 1, and FIG. 3 is viewed from a direction indicated by an arrow P in FIG. FIG. 4 is a side view showing a cylinder head cover, and FIG.
-It is an X-ray sectional view.

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.

A fan cover 13 fixed to the right side of the crankcase 7 is provided on the crankshaft 7a.
(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, a spark plug provided on the cylinder head 9 is ignited to drive the internal combustion engine main body 1, and the crankshaft 7a rotates as the piston reciprocates. ing.

Here, the cylinder head cover 10
Is configured as shown in FIGS. That is, the cylinder head cover 10 shown here is the head cover body 1 fixed to the outer end of the cylinder head 9.
1, a lid 12 fixed to the outer end of the head cover main body 11. As shown in FIGS. 4 and 5, the cylinder head 9 has an exhaust valve 9a.
The exhaust port 9 communicates with the exhaust port 9b opened and closed by the
The exhaust port 9c is connected to an exhaust pipe 5 that forms an exhaust passage together with the muffler 6.

In the cylinder head 9, a rocker arm chamber 9d for accommodating a rocker arm of a valve operating mechanism for driving the exhaust valve 9a is formed. Secondary air passage W
2 are formed. That is, the cylinder head 9
The thick portion of the outer wall 91 of the cylinder head cover 10
The downstream secondary air passage W2 is formed linearly along a direction orthogonal to the joining surface 91a with the downstream side. Here, the downstream side secondary air passage W2 is formed by a mold when the cylinder head 10 is cast. At this time, since the lower secondary air passage is formed along the direction orthogonal to the joining surface 91a, the removal of the mold in the casting process can be performed extremely smoothly.

Further, as shown in FIG. 4, the downstream side secondary air passage W2 is formed in a thick portion of the outer wall portion 91 at a position deviated to the outer surface side. That is, the thickness t2 from the downstream secondary air passage W2 to the inner surface 91c is set to be greater than the thickness t1 from the outer surface 91b to the inner surface 91c. The downstream side secondary air passage W2 can be formed at a plurality of locations on the outer wall portion 9c of the cylinder head 9. The processing method includes a method of forming by casting as described above, and a method of forming a machine after casting. It is also possible to adopt a method of forming by processing, and the processing method can be appropriately selected as needed.

On the other hand, a thick portion of the outer wall portion 111 of the head cover body 11 has a joint surface 1 with the cylinder head 9.
The upstream secondary air passage W1 that is linear along the direction orthogonal to the joint surface 91a with the downstream secondary air passage W1
2, and the processing is performed by casting, machining, or the like, similarly to the downstream secondary air passage W2. Further, the upstream side secondary air passage W1 is formed at a position concentric with the downstream side secondary air passage W2, and the arrangement in the thick portion of the outer wall portion 111 is the same as that of the downstream side secondary air passage W2. The thickness T2 from the inner surface 121c to the passage W1 is set to be thicker than the thickness T1 from the outer surface 111b to the upstream secondary air passage W1. In FIG. 4, the upper secondary air passage W1 is formed to have the same diameter as the downstream secondary air passage W2.
The flow rate of the secondary air can be easily controlled by forming the secondary air passage W2 with a smaller diameter than the downstream secondary air passage W2.

In the upper part of the head cover main body 11, a container-shaped valve storage chamber R3 communicating with the upper secondary air passage W1 is formed. A latching step R3a is formed at the edge of the opening of the valve storage chamber R3, and the exhaust air valve 122 is removably mounted thereon. This exhaust air valve 12
Reference numeral 2 includes a substantially rectangular valve support frame 122a and a valve piece 122b having one end fixed to the valve support frame 122a in a cantilever spring shape. The valve piece 122b always closes the opening 122a1 of the valve support frame 122a, and can be opened on the bottom side of the valve storage chamber R3.

On the other hand, the lid 12 is connected to the valve storage chamber R
3 is removably fixed by a screw B22 so as to close the valve support frame 3, and the peripheral edge of the valve support frame 122a is sandwiched and fixed between the valve support frame 122a and the opening edge of the valve storage chamber R3. The lid 12 is formed with a secondary air introduction chamber R2 opposed to the valve storage chamber R3 via the secondary air valve 122, and has a lateral side above the introduction chamber R2. A protruding introduction path R1 communicates with the downstream end of the secondary air inlet tube 15 at an intake port R1a formed at an end of the secondary air introduction path R1.
5a. As described above, the exhaust secondary air inlet tube 15, the introduction passage R1, the introduction chamber R2, the upper circulation passage W1, and the lower circulation passage W2 form the air circulation passage R. The air circulation passage R and the secondary air A secondary air introduction part is formed by the valve 122.

In the general-purpose internal combustion engine according to 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 drive cycles, and negative pressure and positive pressure are generated alternately. . When the exhaust port 9c has a positive pressure, the valve piece 122b of the secondary air valve 122 is closed, and communication between the introduction chamber R2 and the passages W1 and W2 after the valve storage chamber R3 is cut off. The supply of the secondary air to the exhaust port 9c is also shut off.

When the exhaust port 9c has a negative pressure, the valve piece 122b of the secondary air valve 122 is opened, and the valve storage chamber R3 and the introduction chamber R2 communicate with each other. Becomes a communication state. Therefore, the clean secondary air introduced from the air cleaner 3 into the introduction path R1 and the introduction chamber R2 of the cylinder head cover 10 is:
The air is introduced into the valve storage chamber R3 via the exhaust secondary air valve 122, and further introduced into the exhaust port 9c via the upstream passage W1 and the downstream passage W2. 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.

In the above-described embodiment, the secondary air passage W is provided in the cylinder head cover 10 in the secondary air introduction section from the air cleaner 3 to the exhaust port 9c.
And a part that is completely housed in the cylinder head 9, is not exposed to the outside at all, and a part exposed to the outside is a secondary connecting a relatively short distance space from the cylinder head cover 10 to the air cleaner 3. Only the air inlet tube 15 is provided. For this reason, compared with the conventional device in which the entire secondary air introduction unit is exposed to the external space, it is possible to prevent interference with surrounding members or users during transportation or use, and it is easy to handle. .
Moreover, in this embodiment, the secondary air inlet tube 15 exposed to the external space is arranged in the space surrounded by the auxiliary equipment such as the fuel tank 2, the air cleaner 3, and the muffler 6, so that it is more reliable. Interference with surrounding members can be avoided, and it becomes easier to handle.

Further, as described above, the secondary air passage W
Is completely housed in the cylinder head 9 and the cylinder head cover 10, but its formation position is set outside the rocker arm chambers 9d and 12d, so that it is transmitted from the exhaust port 9c to the secondary air passage W. Heat is
The oil is not transmitted to the oil mist in the rocker arm, and carbonization and deterioration of the oil can be prevented. In particular, in this embodiment, the upstream secondary air passage W1
And the downstream side secondary air passage W2 is disposed so as to be deflected outwardly in the thick portion of the outer wall portion 91, and both passages W1 and W2 are formed from the rocker arm chamber through a thick portion. Therefore, heat transmitted from the exhaust port to the secondary air passage W is not transmitted from the outer wall into the rocker arm chamber, and the transmission of heat into the rocker arm chamber can be more reliably prevented. .

Further, the cylinder head cover 10 in this embodiment has a head cover main body 11 and a lid 12 which are separably combined by bolts B22 or the like, and a secondary air valve 122 is attached to the lid 12 by the cover main body 11.
Since the secondary air valve 122 is replaced,
This 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.

In the above embodiment, the number of the secondary air passages W is plural. However, the number of the secondary air passages W may be set to a single value depending on the diameter of the secondary air passage to be formed. However, the number is not necessarily limited to a plurality. Further, the shape of the air passages W1 and W2 is not limited to a linear shape, and may be a bent shape. When the air passages W1 and W2 are formed by machining, they are joined as in the above embodiment. It is not necessary to form it along a direction perpendicular to the surface, and it may be formed at an acute angle or an obtuse angle with respect to the joint surface.

[0029]

As described above, according to the present invention, the following effects can be obtained. That is, according to the first aspect of the present invention, since the cylinder head and the cylinder head cover form the secondary air passage from the exhaust port to the cylinder head, the portion exposed to the external space is separated from the cylinder head cover by the air cleaner. Only the short secondary air inlet tube that connects between the two, the occurrence of the inconvenience of hooking the secondary air inlet tube on an external member during transportation or use can be greatly suppressed, and it is extremely easy to handle It has the effect of becoming something.

Further, even if the secondary air passage is overheated by the heat of the exhaust gas discharged to the exhaust port, since the secondary air passage is located outside the rocker arm,
The heat of the secondary air passage is not transmitted to the oil mist in the rocker arm, and there is an effect that deterioration and carbonization of the oil can be greatly reduced. Further, since all parts except the secondary air valve are housed in the cylinder head cover and the cylinder head, there is an effect that the production can be made extremely compact.

Further, in the invention according to the second aspect of the present invention, since the valve storage chamber is formed in the cylinder head cover and the valve is stored in the valve storage chamber, the valve can be mounted simultaneously with the mounting and dismounting of the cylinder head cover. This has the effect of facilitating manufacture, maintenance, and the like. Further, in the invention described in claim 3 of the present application, the upstream passage and the lower passage are respectively formed by through holes formed linearly in a direction substantially orthogonal to the joint surface between the cylinder head and the cylinder head cover. Therefore, the upper and lower passages can be easily formed. In particular, when the passage is formed by a mold in the casting of the cylinder head and the cylinder head cover, good releasability can be obtained, and the production becomes easy.

Further, according to the present invention, since a plurality of the upstream passages and the downstream passages are formed, the flow rate of the secondary air can be accurately controlled by the number of the passages. Further, according to the invention described in claim 6 of the present application, since the secondary air inlet tube is surrounded by the auxiliary device, there is no inconvenience that the secondary air inlet tube is caught on the outside even in the secondary air inlet tube, and it is easier to handle. It has the effect of becoming.

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

FIG. 4 is a sectional view taken along the line XX of FIG. 1 and FIG. 2;

FIG. 5 is an exploded view of the head cover shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Internal combustion engine main body 2 Fuel tank 3 Air cleaner 4 Vaporizer 5 Exhaust pipe 6 Muffler 7 Crankcase 8 Cylinder 9 Cylinder head 9c Exhaust port 9d Rocker arm chamber 10 Cylinder head cover 12d Rocker arm chamber 15 Secondary air inlet tube 91 Outer wall part 91a Joint surface 111a Joint surface 121 Outer wall 122 Secondary air valve E General-purpose internal combustion engine R Air circulation path R1a Intake port R3 Valve storage chamber W Secondary air passage W1 Upstream passage W2 Downstream passage

Claims (6)

[Claims] A cylinder head cover is provided at an outer end of a cylinder head fixed to a crankcase via a cylinder, a rocker arm chamber is formed by the cylinder head and an outer wall of the cylinder head cover, and exhaust gas in the cylinder head is provided. A general-purpose internal combustion engine that discharges gas from an exhaust port formed in the cylinder head to a predetermined exhaust path, and an exhaust gas provided with a secondary air introduction unit that introduces secondary air into the exhaust port In the purifying apparatus, the secondary air introduction unit includes: a secondary air passage formed from an intake port formed in the cylinder head cover to an exhaust port of the cylinder head; and a secondary air passage provided in the secondary air passage. A secondary air valve, a secondary air inlet tube connecting the air inlet of the secondary air passage and an air cleaner. And blanking is provided, the secondary air passage, the outer wall of the cylinder head cover and the cylinder head, an exhaust gas purifying apparatus for a general-purpose engine, characterized in that it is Ku轄 formed outward from said rocker arm chamber. The cylinder head cover includes a rocker arm chamber, a valve storage chamber formed outside the locker arm chamber, and an upstream passage communicating with an upstream end portion of the valve storage chamber. An arm chamber, and a downstream passage formed in an outer wall thereof and communicating with an upstream end of the upstream passage. The valve storage chamber stores a secondary air valve and a secondary air valve. An exhaust gas purifying apparatus for a general-purpose internal combustion engine, wherein an intake port is formed on a more upstream side, and a secondary air inlet tube connecting pipe is connected to the intake port. 3. The apparatus according to claim 1, wherein the upstream passage and the downstream passage are respectively formed by through holes formed linearly in a direction substantially orthogonal to a joint surface between the cylinder head and the cylinder head cover. 3. The exhaust gas purifying apparatus for a general-purpose internal combustion engine according to 2. 4. The exhaust gas purifying apparatus for a general-purpose internal combustion engine according to claim 2, wherein a plurality of upstream passages and downstream passages are formed in the cylinder head cover and the cylinder head. 5. The exhaust gas purifying apparatus for a general-purpose internal combustion engine according to claim 2, wherein the upstream passage and the downstream passage are formed by casting, machining, or a combination of both. 6. The exhaust gas purifying apparatus according to claim 1, wherein the secondary air inlet tube is disposed in a space surrounded by an auxiliary device connected to a general-purpose internal combustion engine body.