JPH02140450A - Carbureter - Google Patents

Abstract

PURPOSE:To better connection from a low speed fuel to a main fuel and get rid of a back breeding phenomenon at a high load operation sphere, by providing the 1st low speed fuel passage branching off from a main fuel passage and the 2nd low speed fuel passage issuing from a fixed oil surface chamber, on the upper stream side than the low speed jet of the 1st low speed fuel passage, and changing fuel passages by means of a solenoid valve according to load. CONSTITUTION:The 2nd low speed fuel passage 20 which issues from a fixed oil surface chamber 19 is provided on the upper stream side than the low speed jet 13 of the 1st low speed fuel passage 12, and thereat, a changeover valve 21 driven electro-magnetically is provided. The changeover valve 21 has a valve seat 23 at the 1st low speed fuel passage 12 and a valve seat 24 at the 2nd low speed fuel passage. A valve body 22 is seated at the valve seat 24 from an engine start time to a middle load operation sphere, and the low speed fuel passage becomes that of a common shape by means of the 1st low speed fuel passage 12 which has branched off from a main fuel passage 6. At a high load operation sphere, the valve body 22 is seated at the valve seat 23 and the low speed fuel passage becomes that of an independent shape by means of the main fuel passage 6 and the separate 2nd low speed fuel passage 20. As a result, a carbureter having the merits of the common and independent forms is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field 1] The present invention mainly relates to a carburetor for supplying fuel to an automobile engine.

[Prior Art] As is well known, there are two types of low-velocity fuel passages in a carburetor: a common type and an independent type. The low-speed fuel passage of the common type branches off from the middle of the main fuel passage and leads to the idle boat and slow boat, whereas the low-speed fuel passage of the German α type has a constant oil level chamber completely separate from the main fuel passage. from idle boat,
A common type is generally adopted for everything from slow boats.

[Problem to be solved by the invention] In the common type, since the main fuel passage and the low-speed fuel passage interfere with each other, the main fuel suction start timing is relatively appropriate, and the fuel in the transition area from the low-speed fuel to the main fuel is Although the supply is good, during high-load operation, the negative pressure acting on the low-speed fuel passage is weak, so a phenomenon in which air flows backward from the low-speed air bleed through the low-speed jet to the main fuel passage, that is, the bank bleed phenomenon occurs. When this back-bleed phenomenon occurs, the air-fuel mixture becomes diluted rapidly, which impairs drivability. On the other hand, in the independent type, there is no mutual interference between the main fuel passage and the low-speed fuel passage, so the backbleed phenomenon does not occur. be.

The present invention was invented for the purpose of eliminating the disadvantages of both the common type and the independent type and providing a carburetor that combines only the advantages of each type.

[Means for solving the problem] As a means for solving the problem, a first low-speed fuel passage branched from the main fuel passage and a lower-speed jet in the first low-speed fuel passage from a constant oil level chamber are provided. A second low-speed fuel passage connected to the upstream side is closed upstream of a connection point between the first low-speed fuel passage and the second low-speed fuel passage in a high-load operation region, and the second low-speed fuel passage is opened. +'+i+ An electromagnetically driven switching valve that communicates with the low-speed jet, but in other operating ranges closes the second low-speed fuel passage and listens to the first low-speed fuel passage.

[Function] From engine start to medium load operation range? ti... The second low speed fuel passage is closed by the driven switching valve, and the first low speed fuel passage becomes a normal common type low speed fuel passage. Therefore, fuel supply is performed satisfactorily in the n range where the main fuel suction start timing is appropriate (and continues). When the high-load operating range is reached, the switching valve closes the first low-speed fuel passage 6 upstream from the connection point with the second low-speed fuel passage, and the second low-speed fuel passage opens and communicates with the low-speed jet, which is an independent low-speed fuel passage. becomes. Therefore, the backbleed phenomenon is prevented and the operability in the high load operating range becomes stable.

[Implementation Example 1] Embodiments of the present invention will be described with reference to the drawings.

In the drawing, 1 is the carburetor main body, 2 is the intake passage, 3 is the throttle valve, 4 and 5 are two large and small venturis provided in the intake passage 2, 6 is the main fuel passage, 7 is the main jet, and 8 is the main. 9 is a main nozzle, 10 is a main air bleed, 11 is a bleed pipe, 12 is a first fuel passage branched from the main fuel passage 6 and has a low-velocity jet 13, 14 is an economizer bleed, 15 is an economizer, and 16 is a Low speed air bleed, 17 is idle boat, 18 is slow boat 1~.
19 indicates a constant oil level chamber.

Then, from the constant oil level chamber 19 to the first low speed fuel passage 12 (l
(A second low-speed fuel passage 20 connected to the upstream side of the high-speed jet 13 is provided. An electromagnetically driven switching valve 21 is installed which opens and closes the passage 20 in alternating directions. 2 Valve seat 2 installed in the low speed fuel passage
It is seated or separated alternately with 4.

From engine start to medium load operation range, the valve body 22 is seated on the valve seat 24 to open the second low speed fuel passage 20, so that the low speed fuel passage is connected to the first low speed fuel passage branched from the main fuel passage 6. A common shape is formed by the passage 12.

When the high fl v1 operating range is reached, the switching valve 21 is actuated by a drive signal from the electronic control device 25, and the valve body 22 is separated from the valve seat 24 and is seated on the valve seat 23.

Therefore, the low speed jet 13 is cut off from the main fuel passage 6 and at the same time communicates with the second low speed fuel passage 20 . It is an independent type.

This switching is carried out by supplying or cutting off current to the solenoid of the switching valve 21 from the electronic control 611 device 25 into which the suction pipe negative pressure, engine speed, throttle valve opening, etc. are input.

[Effects of the Invention] As described above, the present invention has a first low-speed fuel passage branched from the main fuel passage, and a second low-speed fuel passage connected from the constant oil level chamber to the F flow side of the first low-speed fuel passage. A low-speed fuel passage is provided, and a Ti electromagnetic drive switching valve is installed at this VC contact point.
The low-speed fuel passage is of a common type from the time the engine starts to the medium-load operation range, and in the high-load operation range, the switching valve is activated and becomes an independent type. Just like the common type, the main fuel passage and the low-speed fuel passage mutually interfere with each other, so that the main fuel suction starts at an appropriate timing, and the transition from the low-speed fuel to the main fuel is performed well. , In the q operating range, the back bleed phenomenon disappears and the mixture becomes leaner than tn because it is an independent type.
<Deterioration of drivability will also be eliminated. That is, the present invention provides a carburetor that has only the advantages of the common type and the independent type.

In addition, by electromagnetically driving the switching valve, the engine operating condition can be detected and the initial switching can be performed reliably and there will be no malfunction.

[Brief explanation of the drawing]

The drawings are longitudinal cross-sectional views of embodiments of the present invention. 1... Carburetor main body, 6... Main fuel passage, 12... First low speed fuel passage, 13...
・Low speed jet, 19... Constant oil level chamber, 20...
...Second low-speed fuel passage, 21...Switching valve,
22... Valve body fee 3! e-person Mutsuki Nozawa

Claims (1)

[Claims] A first low-speed fuel passage branched from the main fuel passage; a second low-speed fuel passage connected from the constant oil level chamber to the upstream side of the low-speed jet in the first low-speed fuel passage; The upstream side of the connection point with the second low-speed fuel passage of the low-speed fuel passage is closed, and the second low-speed fuel passage is connected to the low-speed jet, but in other operating ranges, the second low-speed fuel passage is closed and the second low-speed fuel passage is closed. and an electromagnetically driven switching valve opening the first low-speed fuel passage.