JPS5822967Y2 - Engine secondary air supply system - Google Patents

Description

[Detailed description of the invention] This invention uses the pulsation of exhaust gas to supply secondary air to the exhaust system of a so-called cross-flow type engine, in which the intake port and exhaust port open on opposite sides of the cylinder head. The present invention relates to an improvement in a secondary air supply device for an engine.

Conventionally, as a secondary air supply device for this type of engine, a reed valve is interposed in the secondary air supply passage, and the reed valve is opened and closed using the pulsation of exhaust gas to supply secondary air to the exhaust system. By supplying unburned components (HC,
It is well known that exhaust gas is purified by re-combusting CO).

However, conventionally, most of the secondary air supply devices using such a closed valve directly connect the outside air introduction part of an air cleaner or the like and the exhaust system with a pipe or hose as a secondary air supply passage. , a reed valve is placed between them, but there is a problem in that the tapping sound generated when the reed valve opens and closes due to the pulsation of exhaust gas leaks outside from the reed valve case wall and pipe, causing noise. can be,
There was also the problem that the reed valve would burn out due to the high temperature exhaust gas when the exhaust gas flows backwards.

In addition, because the pipes or hoses that make up the secondary air supply passage are connected from the intake system to the exhaust system by bypassing the engine, the passage length is long, the structure is complicated, and the equipment is not easy to mount. there were.

Therefore, the present invention has been made in view of this point, and in the secondary air supply device using the exhaust pulsation method in the loss flow type engine as described above, the reed valve is made of aluminum, which has excellent sound absorption and damping properties. By mounting the cylinder head, which is made of a cast metal such as the like, by surrounding the mating surface of the intake manifold, it is possible to prevent the noise caused by the tapping sound of the reed valve from escaping to the outside, and to supply secondary air into the cooling water passage of the cylinder head. By forming a passage, exhaust gas salts during backflow of exhaust gas can be lowered and adverse effects on the reed valve can be prevented.Furthermore, by forming a secondary air passage integrally with the intake manifold and exhaust manifold, piping can be eliminated or eliminated. It is an object of the present invention to provide a secondary air supply device for an engine in which most of the parts are omitted to make the entire device compact, and a reed valve can be easily installed, thereby solving the above-mentioned conventional drawbacks. It is something.

That is, the present invention provides an engine secondary air system that utilizes the pulsation of exhaust gas to supply secondary air to the exhaust system connected to the exhaust port that opens on one side of the cylinder head, which is different from the intake port. In the air supply device, a recess is formed in one of the cylinder head and the intake manifold at a mating surface between the cylinder head and the intake manifold, a reed valve is installed in the recess, and the reed valve is connected to the air formed in the intake manifold. One of the secondary air supply passages is connected to an air passage that passes through a cooling water passage formed in the cylinder head, and the air passage is connected to an air passage formed in an exhaust manifold. It is characterized by comprising a section.

Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

FIG. 1 shows a first embodiment of the present invention, and 1 is a filter 1a.
2 is a carburetor connected to the air cleaner 1; 3 is an intake manifold made of cast metal such as A1 that supplies the air-fuel mixture generated in carburetor 2 to the engine; 4 is a cylinder block 5 and a cast metal such as AI made cylinder head 6
The intake manifold 3 has an intake passage T formed in the intake manifold 3 on one side of the cylinder head 6, and an intake port formed in the cylinder head 6. It is connected to the cylinder head 6 via a gasket 9 so as to communicate with the combustion chamber 4 via a gasket 8 .

10 is an exhaust manifold, and an exhaust passage 11 formed in the exhaust manifold 10 on the other side of the cylinder head 6 communicates with the combustion chamber 4 via an exhaust port 12 formed in the cylinder head 6. is connected to the cylinder head 6 via a gasket 13.

An air passage 14 is further formed in the intake manifold 3, and one end of the air passage 14 is communicated with the inside (clean side) of the filter 1a of the air cleaner 1 via a pipe 15, while the other end is connected to the intake manifold 3. It opens at a mating surface portion 16 between the cylinder head 6 and the cylinder head 6.

A recess 17 communicating with the air passage 14 is formed in the cylinder head 6 at a mating surface 16 between the intake manifold 3 and the cylinder head 6 where the air passage 14 opens;
A reed valve 18 is installed within the recess 17 .

Furthermore, an air passage 20 is formed in the cylinder head 6, passing through the cooling water passage 19 formed in the cylinder head 6, and one end of the air passage 20 is connected to the recess 1γ.
The other end is open to the exhaust passage 11 in the exhaust manifold 1a via an air passage 21 formed in the exhaust manifold 1a.

The pipe 15, the air passage 14, the recess 17, the air passage 20, and the air passage 21 constitute a secondary air supply passage 22 that supplies secondary air from the air cleaner 1 to the exhaust passage 11. Due to the pulsation of exhaust gas in the passage 11, when the pressure is negative, the valve body 18a of the reed valve 18 is opened to supply secondary air to the exhaust passage 11, and when the pressure is positive, the valve body 18a is closed and the exhaust gas is transferred to the secondary air supply passage 22. It is configured so that the air does not flow back to the air cleaner 1 via the air cleaner 1.

Therefore, in the first embodiment, the reed valve 18 is disposed in the recess 1γ provided in the cylinder head 6 in the mating surface 16 of the intake manifold 3 and the cylinder head 6. Since the intake manifold 3 and the cylinder head 6 are made of cast metal with excellent sound absorption and damping properties, the tapping noise caused by the opening and closing of the valve body 18a is difficult to leak outside. Therefore, the generation of noise can be reduced.

Moreover, since the air passage 20 forming a part of the secondary air supply passage 22 is passed through the cooling water passage 19 of the cylinder head 6 and communicated with the recess 17, when the exhaust gas flows back, the exhaust gas is When the air flows backward in the air passage 20, the cooling water passage 19 is also cooled by the cooling heat, and the exhaust gas temperature decreases.
burnout can be reliably prevented.

In particular, in the case of this example, the recess 1 provided on the cylinder head 6 side
By installing the reed valve 18 on the T, the reed valve 18
Since the reed valve itself is also cooled by the cooling heat from the cooling water passage 19, burnout of the reed valve 18 can be more reliably prevented.

In addition, when the outside temperature is low, the engine cooling water is at a certain high temperature after the engine starts, even though the outside temperature is low, so when the secondary air passes through the air passage 20, cooling water is By being heated by the temperature of the cooling water flowing through the water passage 19, the reactivity with the exhaust gas in the exhaust passage 11 improves, and unburned components are effectively re-burned to improve exhaust gas purification. can.

Furthermore, by providing the air passage 14, the recess 17, and the air passage 20, which constitute a part of the secondary air supply passage 22, in the intake manifold 3 button and the cylinder head 6 in a cross-flow type engine, it is possible to eliminate the need for conventional pipes. Compared to a system that connects an air cleaner or the like to an exhaust system, the effective space of existing members is utilized, so the entire system has the advantage of being extremely compact.

In addition, by providing the reed valve 18 on the mating surface between the cylinder head 6 and the intake manifold 3, the reed valve 18
8 is advantageous because the structure becomes extremely simple.

Furthermore, FIG. 2 shows a second embodiment of the present invention, and in the first embodiment (FIG. 1), the recess 17 in which the glued valve 18 is mounted is replaced with the mating surface of the cylinder head 6 and the intake manifold 3.
6, a mating surface portion 16 between the intake manifold 3' and the cylinder head 6' is provided.
A recess 1γ' for mounting a reed valve 18' is provided in the intake manifold 3' at '.

That is, as shown in FIG. 2, the intake manifold 3'
The reed valve 1 is attached to the mating surface 16' with the cylinder head 6'.
An air passage 14' formed in the intake manifold 3' opens into the recess 17', while the other end is connected to the air passage 14' through a pipe 15' as shown in the figure. Although not connected, it is connected to the air cleaner.

Additionally, an air passage 20' is formed in the cylinder head 6' by a pipe 23 that passes through a cooling water passage 19' formed inside the cylinder head 6', and one end of the air passage 20' opens into the recess 17'. On the other hand, the other end is connected to the exhaust passage (not shown), and the pipe 15' and the air passage 1 are connected to each other.
4', the recess 17', the air passage 20', and the like constitute a secondary air supply passage 22'.

The rest of the structure is the same as that of the first embodiment (FIG. 1), and its effects are also the same as those of the above embodiment.

As explained above, according to the present invention, in a secondary air supply device using a reed valve in a cross-flow type engine, it is possible to prevent the tapping sound caused by the reed valve from leaking outside. It is possible to reduce this, and also to reliably prevent burnout of the reed valve during backflow of exhaust gas.

In addition, when the external temperature is low, the secondary air can be heated to improve its reactivity with exhaust gas, so that exhaust gas purification can be improved.

Furthermore, by forming the secondary air supply passage in an existing member, the device can be made more compact, and the reed valve also has the advantage of being simple in structure.

[Brief explanation of the drawing]

The drawings illustrate embodiments of the present invention, and FIG. 1 is a schematic cross-sectional view showing the first embodiment, and FIG. 2 is a cross-sectional view of essential parts showing the second embodiment. 1... Air cleaner, 1a... Filter, 2...
Carburetor, 3, 3'... Intake manifold, 4... Combustion chamber, 5... Cylinder block, 6, 6'... Cylinder head, T... Intake passage, 8... Intake port ,
9...Gasket, 10...Exhaust manifold, 1
1... Exhaust passage, 12... Exhaust port, 13...
Gasket, 14, 14'... air passage, 15,
15'...pipe, 16,16'...mating surface part, 1
γ, 17'... Recessed portion, 18, 1 B'... Reed valve, 18a... Valve body, 19, 19'... Cooling water passage, 20. 20'... Air passage, 21. ...Air passage, 22゜22'...Secondary air supply passage, 23...pipe.

Claims (1)

[Scope of utility model registration request] This is a cross-flow type engine in which an intake port and an exhaust port are formed on opposite sides of the cylinder head, and the exhaust system connected to the exhaust port is connected to the exhaust system through a road valve that opens and closes depending on the pulsation of exhaust gas. In a secondary air supply device for an engine that supplies secondary air, a recess is formed in one of the cylinder head or the intake manifold at the mating surface between the cylinder head and the intake manifold, a reed valve is mounted in the recess, and the intake manifold is fitted with a reed valve. An air passage is integrally formed in the manifold, one end of which communicates with the clean side of the air cleaner and the other end of which is connected to the reed valve.
The reed valve is connected to an air passage that passes through a cooling water passage formed in the cylinder head, while an air passage whose one end communicates with the exhaust passage is integrally formed in the exhaust manifold, and the air passage is connected to the cylinder head. A secondary air supply device for an engine, characterized in that it is connected to an air passage formed in a head and constitutes a part of a secondary air supply passage.