JPS6313410Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a deceleration device for a carburetor that prevents the discharge of unburned hydrocarbons, etc. from exhaust gas during deceleration while the vehicle is running, and also prevents afterburning due to misfire. .

Conventionally, in the deceleration device of a carburetor, when decelerating,
When the intake tract negative pressure downstream of the throttle valve reaches a certain level,
The deceleration device is activated to close the low-speed air passage and enrich the low-speed air-fuel mixture, aiding combustion in the engine, preventing the discharge of unburned hydrocarbons, and preventing afterburning due to misfires.

However, in such a conventional speed reduction device,
The low-speed air-fuel mixture during engine deceleration has a constant concentration regardless of the magnitude of the intake tract negative pressure, so if this mixture concentration is selected to be suitable for a small intake tract negative pressure, the intake tract negative pressure will increase. If it becomes larger than that, i.e. at the beginning of deceleration, etc., the engine will not be supplied with a rich mixture suitable for it, and the combustion components will be insufficient.
There is a drawback that unburned hydrocarbons are discharged and afterburning occurs due to misfires.Also, if the mixture concentration is selected to be suitable for cases where the intake tract negative pressure is large, the intake tract negative pressure will be lower than that. When the engine speed decreases, for example, after the middle stage of engine deceleration, a slightly richer air-fuel mixture is supplied to the engine, resulting in an increase in carbon monoxide in the exhaust gas.

The present invention aims to provide a speed reduction device with a simple structure that supplies an appropriate rich mixture according to the deceleration state of the engine and prevents unburned hydrocarbons, carbon monoxide, and afterburning generated during engine deceleration. purpose.

In the low-speed system of a carburetor, the present invention disposes an on-off valve that is operated by the negative pressure in the intake tract that increases during deceleration in the middle of the low-speed air passage that supplies air to the low-speed system, and the low-speed air passage upstream and the on-off valve side opening of the low-speed air passage is arranged on the side of the valve chamber of the on-off valve and in the operating direction of the on-off valve, and further, the on-off valve corresponds to the opening position of the low-speed air passage. During deceleration when the intake tract negative pressure is relatively small, the on-off valve is half-opened against one spring, blocking only one low-speed air passage, and reducing the intake tract negative pressure. The present invention is characterized in that during a relatively large deceleration, the on-off valve is fully closed against the spring as well as another spring, thereby blocking both low-speed air passages.

Hereinafter, one embodiment of the deceleration device of the present invention will be explained based on the drawings. 1 is the carburetor body, 2 is the intake path, and 3 is the carburetor body.
4 is a throttle valve, 4 is a low-speed mixture passage, 5 is a low-speed fuel passage, 6 is a low-speed air passage, 7 is a valve chamber provided in the middle of the low-speed air passage 6, and the low-speed air passage 6 upstream of the valve chamber 7 is It is divided into a first low-speed air passage 8 and a second low-speed air passage 9, and openings 8' and 9' on the valve chamber 7 side of the first low-speed air passage 8 and the second low-speed air passage 9 are arranged at upper and lower positions, respectively. ing. An on-off valve 10 is slidably accommodated in the valve chamber 7, and a diaphragm 1 is provided at the upper end of the on-off valve 10.
1 is fixed, an atmospheric chamber 12 is formed above the diaphragm 11, and a negative pressure chamber 13 is formed below the diaphragm 11. They are communicated by a passage 14.
A small diameter portion 15 is formed in the upper part of the on-off valve 10, a plate 16 is slidably fitted into the small diameter portion 15, and a short spring 17 is interposed between the plate 16 and the diaphragm 11. The plate 16 is seated on the shoulder 18 of the normally open/close valve 10. Further, a long spring 19 is disposed within the negative pressure chamber 13, and this long spring 19 always urges the diaphragm 11 upward. Reference numeral 20 denotes an engaging portion formed at the lower part of the negative pressure chamber 13, on which the plate 16 is seated.

According to the deceleration device of the present invention having the above structure,
When the engine is accelerating and running at constant speed, the intake path 2
Since the negative pressure does not become large enough to operate the deceleration device, the on-off valve 10 is positioned at the uppermost position by the action of the long spring 19, and both the first low-speed air passage 8 and the second low-speed air passage 9 are held open to maintain proper operation. Supply mixture for low speed.

Next, when the speed is reduced from when driving at a constant speed,
When the negative pressure in the intake passage 2 is small, the diaphragm 11 is attracted by the negative pressure acting in the negative pressure chamber 13, as shown in FIG. 2, and moves downward against the force of the long spring 19. Along with this, the on-off valve 10 descends until the plate 16 is seated on the engaging portion 20, closes only the first low-speed air passage 8, reduces the low-speed air, forms a rich mixture, and supplies it to the engine. .

Furthermore, when the negative pressure in the intake passage 2 is large, the diaphragm 11 is further attracted by the negative pressure acting in the negative pressure chamber 13 as shown in FIG. The diaphragm 11 is also moved downward. At the same time, the on-off valve 10 descends until it seats on the low wall of the valve chamber 7, closes both the first low-speed air passage 8 and the second low-speed air passage 9, and supplies an even richer low-speed air-fuel mixture to the engine. supply

That is, when the negative pressure in the intake passage 2 is large, such as at the beginning of engine deceleration, a relatively rich low-speed mixture is supplied to the engine, and when the negative pressure on the intake passage 2 is small, such as after the middle stage of engine deceleration, etc. A low-speed air-fuel mixture with a slightly lower air-fuel mixture concentration than in the above case is supplied to the engine.

As detailed above, according to the present invention, the mixture concentration during engine deceleration is changed in stages according to the magnitude of the intake tract negative pressure, so that an appropriate rich mixture can be maintained during engine deceleration. It can be supplied to the engine and is extremely effective in preventing unburned hydrocarbons, carbon monoxide, and afterburning that occur during engine deceleration.

In addition, one on-off valve is configured to stroke in two stages depending on the magnitude of the intake negative pressure, thereby blocking one or both of the two low-speed air passages, so multi-stage correction is possible as described above. It is possible to provide a speed reduction device with a simple configuration.

[Brief explanation of the drawing]

Figure 1 is a system diagram of one embodiment of the present invention, Figures 2 and 3 are longitudinal sectional views showing the main parts of the present invention, and Figure 2 is a
FIG. 3 shows a state in which only one air passage is closed, and FIG. 3 shows a state in which two air passages are closed. DESCRIPTION OF SYMBOLS 1... Carburetor main body, 2... Intake path, 6... Low speed air passage, 8... First low speed air passage, 9... Second
Low speed air passage, 10...open/close valve.

Claims (1)

[Scope of utility model registration request] In the low-speed system of the carburetor, an on-off valve that is activated by the negative pressure in the intake tract that increases during deceleration is placed in the middle of the low-speed air passage that supplies air to the low-speed system, and two low-speed air passages are provided upstream of the valve. With,
The on-off valve side opening of this low-speed air passage is arranged on the side of the valve chamber of the on-off valve and in the operating direction of the on-off valve, and furthermore, the on-off valve acts in stages corresponding to the opening position of the low-speed air passage. It is held by two springs, and when the intake tract negative pressure is relatively small during deceleration, the on-off valve is opened half-open against one spring to close only one low-speed air passage, and when the intake tract negative pressure is relatively large during the deceleration, A speed reduction device for a carburetor, characterized in that an on-off valve is fully closed against the spring and another spring, thereby blocking both low-speed air passages.