JPS6114345B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an internal combustion engine that enables lean combustion to purify exhaust gas.

[Conventional technology]

BACKGROUND ART Conventionally, as a method for purifying exhaust gas from an internal combustion engine and improving fuel efficiency, it has been known to dilute a supplied air-fuel mixture to near the flammability limit.

[Problem that the invention seeks to solve]

However, diluting the air-fuel mixture in this way makes combustion unstable during idling and low-load operation, which can actually increase harmful components in exhaust gas and worsen driveability and fuel efficiency. There is a contradiction, and we have no choice but to rely on combustion with a slightly rich mixture that emphasizes drivability at low loads.

The present invention eliminates the instability of combustion during idling and low-load operation as described above, achieves sufficient dilution of the air-fuel mixture as the load increases, and reduces harmful components in exhaust gas. The object of the present invention is to provide an internal combustion engine that can also achieve improved fuel efficiency.

[Means for solving problems]

To achieve this objective, the internal combustion engine according to the invention is provided with an auxiliary intake passage parallel to the intake passage of the carburetor, the passage opening at its downstream end towards the spark plug in the combustion chamber, and whose upstream side The system is configured to measure the flow rate from the fuel source through the auxiliary fuel jet and the amount of air through the auxiliary air bleed to generate and supply the air-fuel mixture. A small hole is formed in the intake passage at a position that is closed by the periphery of the throttle valve, and immediately upstream thereof, and at a position that is far away from the periphery of the throttle valve toward the upstream side depending on the opening degree of the throttle valve. According to the opening of the throttle valve, the supply of auxiliary fuel is increased at low loads, decreased as the load increases, and finally becomes almost no supply at all.

Regarding the intake passage that opens immediately before the intake valve, there is a prior art related to Japanese Patent Application Laid-Open No. 51-92903, but this has a completely different upstream configuration.

[Effect]

With the above means, the auxiliary fuel is supplied from the downstream opening of the auxiliary intake passage communicating with the fuel source, depending on the opening of the throttle valve, at low loads.
As the load increases, the amount decreases, and finally, it is supplied to the spark plug in the combustion chamber, swirling the air-fuel mixture to eliminate combustion instability during idling and low-load operation. As a result, it is possible to provide an internal combustion engine that achieves stable combustion even if slow combustion is made leaner than before, reduces harmful components in exhaust gas, and enables lean combustion.

〔Example〕

Embodiments of the present invention will be specifically described below with reference to the drawings.

In the figure, 1 is a carburetor, 2 is an intake passage, 3 is a throttle valve provided in the intake passage 2 of the carburetor 1, 4 is a float chamber, 5 is a fuel passage, and 6 is a throttle branched from the fuel passage 5. Fuel passage, slow air bleed 6a
The air introduced from the engine is mixed and communicated with the idle fuel port 6b and the bypass fuel port 6c, which have a conventionally known structure. 7 is the engine body, 8 is the cylinder head, and the intake passage 2
The carburetor 1 communicates with the combustion chamber 9 of each cylinder, and air-fuel mixture is supplied by opening and closing the intake valve 10. 11 is an exhaust valve, and 12 is a spark plug.

According to the present invention, an auxiliary intake passage 13 is provided substantially parallel to the intake passage 2 and extends across the carburetor 1 and the cylinder head 8, and the upstream side of this passage 13 is branched from the fuel passage 5 to form an auxiliary fuel jet 16. a fuel passage 15 supplied with fuel via;
It is composed of an air passage 17 through which air is supplied from the atmosphere via an auxiliary air bleed 18, and the downstream side is
The air-fuel mixture is opened into the intake passage 2 immediately before the intake valve 10 and is directed so that the air-fuel mixture supplied from the opening 14 when the intake valve 10 is opened flows toward the spark plug 12.

In order to direct the air-fuel mixture to the spark plug 12, a pipe 22 as shown in FIG.
4' may also be formed.

Further, in the case of a two-barrel type carburetor, the auxiliary fuel passage 15 may be branched from the downstream side of the secondary main jet.

Furthermore, a small hole 19 is provided in the auxiliary intake passage 13 so as to communicate with the intake passage 2 at a position that is closed by the peripheral edge of the throttle valve 3 when the valve is opened at idling, and a small hole 19 is provided directly therein so as to communicate with the intake passage 2. A small hole 20 communicating with the intake passage 2 is provided upstream at a position that is gradually spaced further upstream from the periphery of the throttle valve 3 depending on the opening degree of the throttle valve 3.

According to the present invention configured in this way, during idling, the small hole 19 is closed as shown in FIG.
is almost closed off by the peripheral edge of the throttle valve 3, and the auxiliary intake passage 13 communicates with the intake passage 2 only through a small hole 20. Therefore, in this state, the suction negative pressure P' is present in the auxiliary intake passage 13 from the opening 14 at its downstream end, and the pressure P of the intake passage 2 upstream of the throttle valve 3, that is, atmospheric pressure, is applied from the small hole 20. is reaching. That is, P'<P
Therefore, the air-fuel mixture passing through the auxiliary intake passage 13 inhales and combines the air from the small hole 20 and the fuel from the fuel passage 15, becomes different from the air-fuel mixture from the intake passage 2, and flows through the opening 14. is supplied to the combustion chamber 9 from Since the exhaust gas from the previous stroke remaining near the spark plug 12 is stratified and flows in the combustion chamber 9 in a swirling direction as shown by the arrow, ignitability is good and combustion is performed stably. Therefore, the air-fuel mixture in the slow fuel passage can be made much leaner than in the conventional case.

Then, when the throttle valve 3 opens slightly and shifts to load operation, the small hole 19 also opens upstream of the throttle valve 3, as shown in FIG. 3, so that the auxiliary intake passage 13 and the intake passage 2 communicate with each other. become. Then, air flows through the small holes 19 and 20 into the auxiliary intake passage 13 with respect to the fuel taken in from the fuel passage 15.
Since the air-fuel mixture is taken in and merged with the engine, a slightly thinner air-fuel mixture than during idling is supplied to the combustion chamber 9 from the opening 14. At the same time, air-fuel mixture is supplied from the gap between the throttle valve 3 and through the intake passage 2.

As the throttle valve 3 opens, the difference between the pressures P' and P decreases, and both of them tend to approach atmospheric pressure, so the amount of auxiliary mixture supplied from the opening 14 also decreases, causing combustion. The swirling flow within chamber 9 also weakens. That is, in this state, the amount of air-fuel mixture from the intake passage 2 is large and combustion is performed stably, so neither the scavenging nor the swirling flow need be strong.

Furthermore, when the throttle valve 3 opens and high-load operation occurs, the relationship P'≒P becomes as shown in FIG. Almost no air flows, and the air-fuel mixture from the intake passage 2 performs the same output operation as in the past.

Note that in the present invention, the auxiliary intake passage 13 is connected to the opening 1.
The spark plug 1 in the combustion chamber 9 communicates with the intake passage 2 immediately before the intake valve 10 by the spark plug 4 in the combustion chamber 9.
2, an auxiliary intake valve may be provided, and the air-fuel mixture may be supplied by opening and closing the valve.

〔Effect of the invention〕

Thus, according to the present invention, during no-load or low-load operation, a mixture different from the mixture from the intake passage is supplied from the auxiliary intake passage and flows toward the ignition plug, so that the stratification near the ignition plug is sufficient. Since the air-fuel mixture exists as a swirling flow, ignitability is improved, and even if the slow fuel is thinner than before, very stable combustion can be obtained, and during high-load operation, auxiliary intake air Lean combustion is carried out in the same manner as in the past by supplying almost no air-fuel mixture from the passage, which not only reduces harmful exhaust components but also improves fuel efficiency.

Further, the fuel for the auxiliary intake passage may be supplied from an auxiliary fuel passage provided independently from the main system and slow system fuel passages. In this case, smooth fuel supply is performed without any interference due to pressure difference between the main system and slow system passages, and since fuel can be supplied independently, effects such as easy and accurate flow rate adjustment can be obtained.

[Brief explanation of the drawing]

FIG. 1 is an overall view showing an embodiment of the invention, FIGS. 2 to 4 are partially enlarged views showing the operation of the invention, and FIG. 5 is a partial view showing another embodiment of the invention. 1...Carburetor, 2...Intake passage, 3...
Throttle valve, 7... Engine, 9... Combustion chamber, 12... Spark plug, 13... Auxiliary intake passage, 14... Opening, 15... Auxiliary fuel passage, 16
... Auxiliary fuel jet, 17 ... Air passage, 18
...Auxiliary air bleed, 19,20...Small hole.

Claims (1)

[Claims] 1. An auxiliary intake passage is provided in parallel with the intake passage of the carburetor, the downstream end of the passage opens toward the spark plug in the combustion chamber, and the upstream side receives the flow rate from the fuel source via the auxiliary fuel jet. Weigh,
It is configured to measure the amount of air via an auxiliary air bleed to generate and supply a mixture, and
At the position where the throttle valve is closed by the periphery of the throttle valve when the throttle valve is opened at idling, and just upstream thereof, and furthermore, the position is further away from the periphery of the throttle valve upstream depending on the opening degree of the throttle valve. At each position, small holes communicated with the intake passages, and the supply of auxiliary fuel was made more frequent at low loads, decreased as the load increased, and finally became almost absent, depending on the opening of the throttle valve. An internal combustion engine characterized by: