JPS6030452Y2 - Automatic air-fuel ratio control device in carburetor - Google Patents

Description

[Detailed description of the invention] This invention relates to automatic control of air-fuel ratio characteristics during startup and warm-up and in high load ranges.

When starting an internal combustion engine at low temperatures, it is best for the carburetor to supply a rich air-fuel ratio, but if left as is after the internal combustion engine has completely exploded, the engine will stop operating due to the air-fuel ratio being too rich. , a mechanism is needed to immediately reduce the air-fuel ratio to an appropriate level.

In addition, in the high load range of an internal combustion engine, in order to obtain the maximum output of the engine, it is necessary to make the air-fuel ratio slightly richer than in the low and medium load range, and a mechanism for this is required. The functions are performed by one mechanism.

Next, an embodiment of this invention shown in the drawings will be described.

In Figure 1, a is a passage for bleed air intake;
When the passage a is a power jet passage, its bypass passage C
and a breaker jet passage f, and a bypass passage C
and the breaker jet passage f are opened and closed by a valve 3, and the power jet passage is always open through the power jet 5 (jet for A/F setting at high engine load), and the downstream of this jet 5 At , both roads S and C meet at a merging passage d, and the area of the merging passage d is changed by a bushing rod 2, thereby controlling the air-fuel ratio during warm-up.

The merging passage d passes between the bushing rod 2 and communicates with the integrated passage g via the communication passage e.

The breaker jet passage f communicates with the integrated passage g via a breaker jet passage 6 (a jet for A/F setting immediately after the engine is started).

The integrated passage g communicates with the air bleed section 1 of the fuel metering section of the carburetor.

4 is a spring that sets the operating pressure of the valve 3;
h is a negative pressure passage for taking in intake pipe negative pressure, which is the operating source of the valve 3, from the carburetor.

By arranging the passage as shown above, 1
However, the structure of the valve 3 and its related passages is not limited to FIG. Structures as shown in FIGS. 2, 3, 4, and 5 may also be used.

Next, the operation of this invention will be explained.

When the engine is warmed up and stopped, all passages are closed by the action of the valve 3 and bushing rod 2, as shown in FIG.

Next, immediately after starting the engine, the bushing rod 2 remains as it is and the valve 3 is set to a negative pressure of about -10-Hg, so it is immediately pulled by the intake pipe negative pressure to open the breaker jet passage f and the bypass passage C. Since the bypass passage c is closed by the bushing rod 2, only the passage f is actually opened to thin the air-fuel ratio to the value set by the breaker jet 6.

Next, when the engine is warmed up, the bushing rod 2 is moved to the right by a temperature-sensitive operating mechanism (not shown), and the passages d and e are brought into communication and all passages are opened.

Next, when the engine is under high load and the intake pipe negative pressure drops below the operating pressure of the valve 3, the spring 4 returns the valve 3 to close the breaker jet passage f and the bypass passage C, creating a circuit with only the power jet passage. The air-fuel ratio becomes richer to the value set in the jet passage 5, and the output of the engine increases.

As described above, the present invention has the advantage that the two conventional mechanisms described above can be operated by one valve mechanism, thereby making it possible to downsize and reduce costs.

In particular, this invention provides a bypass passage C that is opened and closed by the valve 3 in the power jet passage, so if there is no bypass passage, the amount of bleed that determines the air-fuel ratio after engine warm-up is This is the total of the jet 5 and the breaker jet passage 6, but the power jet 5 and the breaker jet 6 each have a jet size required in different operating conditions, and the total of these jets 5.6 is required after warm-up is completed. Although it rarely matches the aisle area,
As described above, by providing the bypass passage C in the present invention, the flexibility in determining the amount of bleed at the completion of warm-up can be expanded, which is extremely effective in practice.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention, and FIGS.
The figure is a sectional view of main parts showing another embodiment. 1... Air bleed part, 2... Bush rod, 3... Valve, 4... Spring, 5... Power jet, 6... ...
...Breaker jet.

Claims (1)

[Scope of utility model registration request] In a carburetor that controls the air-fuel ratio characteristics suitable for warming up the internal combustion engine by slow or main bleed air in the fuel system, the bleed air intake passage a is connected to the power jet passage b1 the bypass passage c1 of the passage c1 the breaker jet passage f The power jet passage is always in communication with the bleed air intake passage A, and the bypass passage C is divided into three passages.
The breaker jet passage f and the power jet passage are opened and closed simultaneously by one valve 3, and the valve 3 is opened immediately after the engine starts and closed at high load. C communicates with the merging passage d downstream thereof, and communicates the merging passage d with the air bleed section 1 through the integrated passage g via a bushing rod 2 that opens when the engine is warmed up, and further communicates with the breaker jet passage f. An air-fuel ratio automatic control device in a carburetor, characterized in that a downstream side thereof communicates with the integrated passage g.