JPS647238Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) This invention opens the float chamber vent of the carburetor into the intake passage of the engine, and also injects fuel into the fuel passage inside the carburetor in advance. The present invention relates to a bleed air heating device for a vaporizer that heats and introduces air for mixing (bleed air).

(Prior art) Opening the air vent of the carburetor into the intake passage has the effect of preventing the air vent from clogging with dust, but as the ambient temperature rises, it causes a decrease in output and an increase in harmful components in the exhaust gas. As a countermeasure to this problem, a fuel flow rate correction method for a carburetor has been proposed, for example, as described in Japanese Patent Application Laid-open No. 148935/1983.

The method involves heating the bleed air so that it is always higher than the ambient temperature, and determining the amount of heating for the bleed air so that the fuel flow rate for each throttle valve opening is approximately equal regardless of the ambient temperature. It has particular characteristics.

However, as shown in FIG. 1 of the above-mentioned publication, the heating means in this case requires special piping for heating, which has the disadvantage of complicating the structure.

Further, as shown in FIGS. 2 to 5 of the above-mentioned publication, another heating means needs to also heat the intake air, which inconveniently lowers the charging efficiency and lowers the engine performance.

(Purpose of the invention) This invention was made in view of the above-mentioned disadvantages, and aims to simplify the structure of the bleed air heating device and eliminate the need to heat the intake air, thereby preventing the engine performance from deteriorating. The purpose is to

(Structure of the device) In order to achieve the above object, the device opens at a position upstream of the bench lily portion in the intake passage of the carburetor body and extends in the intake air flow direction within the carburetor body. Bleed air passage,
communicates with the downstream end of the first bleed air passage;
A second bleed air passage formed in contact with the intake flange surface on the side of the engine body; and a second bleed air passage formed extending in the intake air flow direction within the carburetor body; A third bleed air passageway is provided for communication with the third bleed air passage.

(Example) Hereinafter, an example of this invention will be described with reference to the drawings.

In FIG. 1, the slow jet 5 provided in the carburetor 1 has its lower end open into the fuel 8 in the float chamber 7 provided at the lower part of the carburetor body 6, and its upper end opens into the intake passage 9 of the carburetor body 6. It is open inward.

On the other hand, the lower end of the main nozzle 11 communicates with the fuel 8 through the main jet 12, and the jet needle 13 is arranged concentrically at the upper end, and opens into the intake passage 9 like the slow jet 5. The space above the liquid level of the fuel 8 in the float chamber 7 communicates with the intake passage 9 through an air vent 15 (float chamber vent). The liquid level of the fuel 8 is always maintained constant by a needle valve (not shown) attached to the float 16. 17 is
The throttle valve 18 is a coil spring that urges the throttle valve 17 downward. 1
9 is a body cap, and 20 is a Bowden wire. This Bowden wire 20 is connected to a throttle lever (not shown), and by pulling the throttle lever, the throttle valve 17 is kept at the fully open position shown, and the throttle valve 17 is kept at the fully open position shown. The needle 13 can be maintained at a position slightly intruding into the main nozzle 11. 22 is a chiyoke valve, 23
indicates an air cleaner, and 32 indicates an air cleaner fixing band.

The carburetor 1 configured in this way is connected to the intake flange 2 via a fitting (not shown), and in this embodiment, a first gasket 3 is attached to the carburetor 1 side.
Also, a second gasket 4 is installed on the intake flange surface 2a side.
An insulator 24 made of phenol resin or the like is attached between both gaskets 3 and 4. The intake flange 2 is integrally formed with the outer end of an intake manifold 25 that protrudes from the engine body E, which is a cylinder.

A bleed air inlet 26 is opened at a position upstream of the bench lily portion in the intake passage 9 of the carburetor body 6 attached in this manner.
This bleed air inlet 26 communicates with a first bleed air passage 27b that is formed by drilling and extends in the intake air flow direction (direction of arrow C) within the carburetor body 6. An intermediate heating passage (second bleed air passage) 27a communicates with the downstream end of the first bleed air passage 27b. This intermediate heating passage 27a is formed in contact with the intake flange surface 2a of the intake manifold 25 on the engine main body E side. In addition, the second gasket 4 has
As shown in FIG. 2, in addition to the intake passage 9 and the bolt insertion hole 30, an elongated through hole 31 is formed with the major axis directed upward and downward, and as shown in FIG. It is configured to partially bring bleed air into contact with the intake flange surface 2a.

The intermediate heating passage 27a includes a carburetor body 6.
A third bleed air passage 27c formed to extend in the upstream direction of intake air (direction opposite to arrow C) is in communication therewith. This third bleed air passage 27
c passes through the main bleed air jet 10,
It communicates with a large number of bleed air holes (small holes) provided in the side wall of the main nozzle 11. Further, the third bleed air passage 27c communicates with a bleed air hole (small hole) provided in the side wall of the slow jet 5 via the slow bleed air jet 14. In other words, the third bleed air passage 27
The intermediate heating passage 27a is communicated with both bleed air jets 10 and 14. A bleed air passage 27 is constituted by the first bleed air passage 27b, intermediate heating passage 27a, and third bleed air passage 27c.

In the above configuration, arrow A in FIG. 1 indicates intake air, arrow B indicates evaporated gasoline, and arrow C indicates air-fuel mixture sucked into the engine.
The air filtered in the air cleaner 23 enters the intake passage 9 as shown by arrow A without being heated.
There, it is mixed with vaporized gasoline B flowing out from the float chamber 7 through the air vent 15, mixed with fuel sucked out from the main nozzle 11, and sucked into the combustion chamber of the engine as shown by arrow C. During this time, the bleed air is introduced into the bleed air passage 27 from the inlet 26, contacts the intake flange surface 2a in the intermediate heating passage 27a of the bleed air passage 27, and receives heat retained by the engine body E. It is heated a certain amount above the ambient temperature. Thus, during normal operation, the fuel enters the fuel through the bleed air hole in the side wall of the main nozzle 11 to promote vaporization, and during low-speed operation, it acts on the slow jet 5.

Therefore, as described above, the bleed air passage 27 is formed in the carburetor body 6, and the intermediate heating passage 27a is arranged to receive heat from the intake flange surface 2a, so that the bleed air is heated. There is no need for any special heaters or piping for this purpose, which simplifies the structure, and since there is no need to heat the intake air A, the filling efficiency of the engine does not decrease. Therefore, the bleed air can be heated without reducing engine performance.

Furthermore, although the carburetor body 6 is insulated by the insulator 24, the intake manifold 2
Some of the heat from 5 has been transferred and it is getting warmer.
Therefore, the bleed air taken in from the bleed air inlet 26 is also heated in the first bleed air passage 27b, which is formed long from a position upstream of the bench lily section to the insulator 24, so that the heating effect of the bleed air is large. .

By the way, without providing the first bleed air passage 27b, as shown in FIG. 3, the heating passage 27d is extended to the outer peripheral end 24a of the insulator 24, and the atmospheric air D is first taken into the heating passage 27d and heated. This is passed through the third bleed air passage 27c in FIG.
It is possible to lead to 14. However, in this case, the effect of heating the bleed air by the first bleed air passage 27b cannot be obtained.

In addition, when the heating passage 27d is formed as shown in Fig. 3, the heating effect of the first bleed air passage 27b (Fig. 1) cannot be obtained as described above, so it becomes necessary to form the heating passage 27d long. Therefore, the sealing performance of the intake flange surface 2a in Fig. 1 is reduced, and the heating passage 27d (Fig. 3)
There is a risk that the air inside the intake passage 9 may be sucked into the intake passage 9 through the intake flange surface 2a. Therefore, the ratio of air in the mixture increases,
The engine's power output decreases.

In contrast, in this invention, since the bleed air can be preheated in the first bleed air passage 27b, the intermediate heating passage 27a in FIG. As a result, engine output is less likely to decrease.

In addition, in the case of a two-stroke engine, the intake flange surface 2a may be constituted by a reed valve body having a reed valve, or the crankcase, in addition to the cylinder. The area of the bleed air passage 27 that corresponds to the flange surface 2a can be set large or small according to the degree of heating required. Furthermore, although the intermediate heating passage 27a of the bleed air passage 27 is provided in the insulator 24 and the second gasket 4 in the embodiment shown in Fig. 1, it may be provided in the engine body E. This means that when the intake flange surface 2a is constituted by the reed valve body, the intermediate heating passage 27a can be provided on either side of the reed valve body and the carburetor body 6, and further, when the insulator 24 and the second gasket 4 are not required, the intermediate heating passage 27a can be provided on either side of the reed valve body and the carburetor body 6.
This means that the bleed air jets 10, 14 may be provided on either the carburetor 1 side or the engine body E side. Also, the bleed air jets 10, 14 may be substituted with holes formed in the carburetor body 6. Furthermore, it goes without saying that the device of this invention can be used for a carburetor that does not have a slow fuel system.

(Effects of the invention) As explained above, according to this invention, the bleed air passage opened in the intake passage is arranged so as to reach the bleed air jet via the intake flange surface on the engine body side, so that the bleed air The structure of the air heating device can be simplified, and there is no need to heat intake air, so there is no risk of deteriorating engine performance.

Moreover, since the first, second, and third bleed air passages are formed, even the long first bleed air passage that extends inside the carburetor body from a position upstream of the bench lily part to the intake flange surface on the engine body side can also be used. , the bleed air can be heated. Furthermore, since the bleed air can be preheated in the first bleed air passage, the second bleed air passage in contact with the intake flange surface can be shortened, so the sealing performance is less likely to deteriorate, and the engine output is less likely to decrease.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of this invention, FIG. 2 is a front view of a second gasket, and FIG. 3 is a front view of an insulator in a bleed air heating device not included in this invention. 1... Carburetor, 2a... Intake flange surface, 6...
... Carburetor body, 7 ... Float chamber, 9 ... Intake passage, 10 ... Main bleed air jet, 1
4... Slow bleed air jet, 15... Float chamber vent (air vent), 27a... Second
Bleed air passage (intermediate heating passage), 27b...
...First bleed air passage, 27c... Third bleed air passage, E... Engine body.

Claims (1)

[Scope of utility model registration request] A bleed air heating device for a carburetor in which a carburetor body forming a bench lily-shaped intake passage is attached to the intake flange surface on the engine body side, and a float chamber of the carburetor is communicated with the intake passage through a float chamber vent. a first bleed air passage that opens at a position upstream of the bench lily in the intake passage and extends in the intake air flow direction within the carburetor body; and a downstream end of the first bleed air passage. A second bleed air passageway is in communication with a second bleed air passageway formed in contact with the intake flange surface on the side of the engine body, and a second bleed air passageway is formed extending in the upstream direction of the intake air within the carburetor body. A bleed air heating device for a vaporizer, comprising a third bleed air passage communicating with an air jet.