JPS6157463B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a protection device for an exhaust purification device provided in an exhaust system of a multi-cylinder internal combustion engine.

In motorcycles and other vehicles equipped with multi-cylinder internal combustion engines equipped with exhaust purification devices, if the ignition circuit of the internal combustion engine is accidentally turned off while driving, the air-fuel mixture supplied from the carburetor to the combustion chamber may not burn. is discharged directly into the exhaust system, so with exhaust purification equipment,
The oxidation reaction of a large amount of fuel components causes the temperature to rise excessively, thereby significantly shortening its life.

The present invention was proposed to eliminate such inconveniences, and when the ignition circuit of a multi-cylinder internal combustion engine is inactive, the pressure inside the float chamber of the carburetor is reduced to suppress the injection of oil from the fuel nozzle. It is an object of the present invention to provide a protection device having a simple structure and capable of preventing excessive temperature rise of the device by restricting the introduction of fuel components into the exhaust purification device.

In order to achieve this purpose, the present invention
In a multi-cylinder internal combustion engine that is provided with a multiple carburetor in the intake system and an exhaust purification device in the exhaust system, the upper part of each float chamber of the multiple carburetor is communicated with each other through a single ventilation passage. A negative pressure passage that is open to the atmosphere and extends from only the intake passage of one of the multiple carburetors is connected in the middle of the ventilation passage via a switching valve, and the switching valve and the ignition circuit are connected to each other through a switching valve. When the ignition circuit is activated, the negative pressure passage is disconnected and the ventilation passage is conducted, and when the ignition circuit is not activated, the upstream side of the ventilation passage is disconnected and the downstream side is communicated with the negative pressure passage. It is characterized by being linked as follows.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. In FIG. ...but the same number of exhaust pipes 4... are also installed on the front,
These exhaust pipes 4... are bent below the engine body 1 and extend to the rear thereof, and are divided into two sets, left and right.
Each set of exhaust pipes 4, 4, 4; 4, 4, 4 is connected to a common muffler 6; 6 via a collecting pipe 5; 5. Each muffler 6 has a built-in catalytic converter 7, which is well known as an exhaust purification device.

As clearly shown in FIG. 3, each carburetor 3 includes an intake passage 8 and a float chamber 9 connected to the intake port of the cylinder 2.
The intake passage 8 is provided with a choke valve 10 on the upstream side and a throttle valve 11 on the downstream side with the bench lily portion 8a in between. In addition, an idle port 12i, a bypass port 12b, and a main nozzle 12m are opened at appropriate positions in the intake passage 8, and both the ports 12i and 12b are connected to the float chamber 9 through the slow jet 13s, and the main nozzle 12m is connected to the float chamber 9 through the main jet 13m. It communicates with the fuel oil inside.

As shown in Fig. 2, the multiple carburetors 3... are divided into two sets, left and right, and each set of multiple carburetors 3, 3, 3;
For convenience, only the left set of multiple carburetors 3, 3, 3 will be described below, since the protection device of the present invention is provided in each of the multiple carburetors 3, 3.

Adjacent vaporizers 3 in multiple vaporizers 3, 3, 3
The upper spaces of the float chamber 9 are communicated with each other by a communication pipe 14, and the only ventilation passage 15 whose one end is open to the atmosphere is connected to this communication pipe 14. Furthermore, an electromagnetic switch is installed in the middle of the vaporization passage 15. A negative pressure passage 17 is connected via a valve 16 .

The negative pressure passage 17 branches into first and second branch passages 17a and 17b from the middle thereof, and the first branch passage 17a is an intake passage of one carburetor 3 among the multiple carburetors 3, 3, 3. The first negative pressure detection hole 18a opens downstream of the throttle valve 11 of No. 8, and the second branch path 17b communicates with the second negative pressure detection hole 18b opened upstream. Also, an orifice 19 is provided in the first branch path 17a.
However, each of the second branch paths 17b is provided with a check valve 20, and the check valve 20 is connected to the second negative pressure detection hole 18.
It allows gas to flow to the b side and prevents reverse flow.

The valve body 21 of the electromagnetic switching valve 16 is connected to the ventilation passage 15.
It operates between a first position where the upstream side of the air passage is closed and the downstream side of the air passage 17 is communicated with the negative pressure passage 17, and a second position where the negative pressure passage 17 is disconnected and the ventilation passage 15 is made conductive. Actuation into its first position is caused by the valve spring 22
The actuation to the second position is effected by the biasing force of the solenoid 23, and the activation of the solenoid 23 respectively. The solenoid 23 is connected in parallel to an ignition circuit 24 of the internal combustion engine E to a battery 27 via a main switch 25 and a kill switch 26.

In the figure, 28 is an air cleaner, and 29 is a rear wheel of the motorcycle arranged between two mufflers 6.

Next, the operation of this embodiment will be explained. When the internal combustion engine E is operating, that is, when the main switch 25 and the kill switch 26 are both closed and the ignition circuit 24 is activated, the solenoid of the electromagnetic switching valve 16
3 also connects the battery 27 through both switches 25 and 26.
Since the valve body 21 is energized and energized from the first
position to the second position shown. As a result, the ventilation path 15 becomes conductive, and the communication pipe 14 is connected to the ventilation path 15.
Atmospheric pressure acts on each float chamber 9, 9, 9 of the multiple vaporizers 3, 3, 3 through
When negative pressure is generated in the intake passage 8 due to the operation of the engine E, the pressure difference with the float chamber 9 causes the chamber 9 to
The fuel is injected from the idle port 12i, the bypass port 12b or the main nozzle 12m into the intake passage 8 to generate an air-fuel mixture, which is then injected into the corresponding cylinder 2.
and is ignited by the ignition circuit 24 to be combusted. The exhaust gas after combustion is discharged into the corresponding exhaust pipe 4 and sent to the muffler 6, and while passing through the muffler 6, unburned components such as HC and CO in the exhaust gas are oxidized and removed by the catalytic converter 7. Thus, the internal combustion engine E generates power and its exhaust gas is purified and released into the atmosphere.

When the kill switch 26 or main switch 25 is opened while the vehicle is running, the ignition circuit 24 is deactivated and the solenoid 23 of the electromagnetic switching valve 16 is turned off.
is also deenergized, the valve body 21 returns to the first position due to the biasing force of the valve spring 22, thereby opening the air passage 15.
Since the upstream side of the negative pressure passage 17 is disconnected and the downstream side of the negative pressure passage 17 is communicated with the negative pressure passage 17,
The negative pressure in the intake passage 8 detected at points a and 18b is transmitted to the negative pressure passage 17, the downstream portion of the ventilation passage 15, and the communication pipe 1.
4 into the float chamber 9 of the adjacent total vaporizer 3, and this introduction action will be explained in more detail.

When the throttle valve 11 is at the low opening position while driving, the negative pressure in the intake passage 8 is higher on the downstream side of the throttle valve 11 than on the upstream side, so the first negative pressure detection hole 1
The high negative pressure detected in the negative pressure passage 17
The water is transmitted through the branch passage 17a, and is prevented from leaking to the second branch passage 17b by the check valve 20, so that it is transmitted to the float chamber 9 side.

Furthermore, when the throttle valve 11 is at the high opening position, the negative pressure in the intake passage 8 is highest at the vent lily part 8a, so the high negative pressure detected at the second negative pressure detection hole 18b near there is the highest in the negative pressure passage. 17 through the second branch passage 17b, and leakage to the first branch passage 17a is restricted by the throttle resistance of the orifice 19, so most of the detected negative pressure is transmitted to the float chamber 9 side. Therefore, high negative pressure can be reliably introduced into each float chamber 9 regardless of the opening degree of the throttle valve 11.

When high negative pressure is introduced into the float chamber 9 in this way, the pressure difference between the intake passage 8 and the float chamber 9 disappears or is significantly reduced, so that the jet from the idle port 12i, bypass port 12b, main nozzle 12m, etc. Oil is immediately suppressed, and the fuel components in the engine E exhaust gas can be minimized. In other words, in the exhaust gas, until then the intake passage 8
It was attached to the inner wall of. or idle port 1
Since only a small amount of fuel remaining in 2i, etc. is included, the load on the catalytic converter 7 that oxidizes and removes it is lightened, and excessive temperature rise of the fuel is avoided.

As described above, according to the present invention, the multiple carburetors 3, 3, 3 are provided in the intake system, and the exhaust purification device 7 is provided in the exhaust system.
In a multi-cylinder internal combustion engine, each float chamber 9, 9, 9 of the multiple carburetor 3, 3,
The upper parts communicate with each other and are open to the atmosphere through only one ventilation passage 15, and in the middle of the ventilation passage 15 is an intake passage of one of the multiple carburetors 3, 3, 3. Negative pressure passage 17 extending only from 8
are connected via a switching valve 16, and when the switching valve 16 and the ignition circuit 24 are activated, the negative pressure passage 17 is closed and the ventilation passage 15 is connected to the ignition circuit 24.
When inactive, the upstream side of the ventilation passage 15 is disconnected, and the downstream side of the ventilation passage 15 and the negative pressure passage 17 are connected to each other.
If the ignition circuit 24 is accidentally deactivated during engine operation, the pressure inside the float chambers 9, 9, 9 will be reduced and the carburetor 3,
The injection of oil from the fuel nozzles 3 and 3 can be immediately suppressed, and as a result, the load on the exhaust purification device 7 can be eliminated or reduced, and damage caused by excessive temperature rise can be prevented. be able to. In particular, the ventilation passage 15, the negative pressure passage 17, and the switching valve 16 for switching and controlling the introduction of atmospheric pressure or intake negative pressure into each float chamber 9, 9, 9 of the multiple carburetor 3, 3, 3 are It is not necessary to separately provide each vaporizer that constitutes the vaporizers 3, 3, 3, and it is sufficient to provide a common set for the multiple vaporizers 3, 3, 3, so the structure is simple, cost is reduced, and This can contribute to improving the ease of assembly.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a multi-cylinder internal combustion engine for a motorcycle to which an embodiment of the present invention is applied, FIG. It is a sectional view taken along the line - in the figure. E...Internal combustion engine, 3,3,3...Multiple carburetor,
7...Catalytic converter as an exhaust purification device, 8
... Intake duct, 9 ... Float chamber, 11 ... Throttle valve,
15...Vent passage, 16...Solenoid switching valve, 17...
Negative pressure passage, 17a...first branch path, 17b...second branch path, 18a...first negative pressure detection hole, 18b...
...Second negative pressure detection hole, 19...Orifice, 20...
...Check valve, 24...Ignition circuit.

Claims (1)

[Scope of Claims] 1. In a multi-cylinder internal combustion engine in which the intake system is provided with multiple carburetors 3, 3, 3, and the exhaust system is provided with an exhaust purification device 7, the multiple carburetors 3, 3, 3 are provided. The upper parts of each float chamber 9, 9, 9 are communicated with each other, and are opened to the atmosphere through the only ventilation passage 15,
In the middle of the ventilation path 15, the multiple vaporizer 3,
A negative pressure passage 17 extending only from the intake passage 8 of one of the carburetors 3 and 3 is connected via a switching valve 16, and this switching valve 16 and an ignition circuit 24 are connected to each other through the operation of the ignition circuit 24. At times, the negative pressure passage 17 is disconnected and the ventilation passage 15 is conducted, and when it is not activated, the upstream side of the ventilation passage 15 is disconnected and the downstream side of the ventilation passage 15 is communicated with the negative pressure passage 17. A protection device for exhaust purification devices for multi-cylinder internal combustion engines. 2 The negative pressure passage 17 branches from the middle thereof to a first negative pressure detection hole 18a that opens downstream of the throttle valve 11 of the intake passage 8, and a second branch passage 17a that opens on the same upstream side. The first branch passage 17a has an orifice 19, and the second branch passage 17b has a check valve 20.
A protection device for an exhaust gas purification device for a multi-cylinder internal combustion engine according to claim 1, wherein the protection device is provided with: