JPH0141886Y2 - - Google Patents

Description

[Detailed explanation of the invention] [Industrial application field] The present invention works as a conventional fixed vent ule type carburetor with an outer vent ule and an inner vent ule in the low load range and practical range, and in the medium load range and high load range. In the engine range, the variable ventilure type carburetor operates the piston valve to change the cross-section of the intake passage, and injects auxiliary fuel according to the displacement of the piston valve, making it possible to supply the optimal air-fuel mixture in all operating ranges of the engine. In particular, the present invention relates to a variable ventilator type carburetor that is capable of injecting auxiliary fuel even when the amount of intake air is small when the piston valve is activated.

[Description of the Prior Art] In a conventional fixed vent ule type carburetor having an inner vent ule and an outer vent ule, if the cross-sectional area of the vent ule part is set large enough to produce the maximum output of the engine, the throttle valve intermediate It becomes difficult to match the air-fuel ratio in the throttle valve opening range and in the low rotation range with the throttle valve fully open.On the other hand, the cross-sectional area of the ventilate part has to be adjusted in consideration of the air-fuel ratio in the throttle valve intermediate opening range and in the low rotation range with the throttle valve fully open. If the engine was made smaller, the engine would not be able to achieve its maximum output, resulting in a problem in that it would not be possible to obtain satisfactory performance in all operating ranges.

Conventionally, to solve this problem,
A jet needle for fuel metering is provided at the tip of the piston valve that changes the intake passage, and various variables are used to adjust the air flow rate passing through the intake passage and the fuel flow rate by the jet needle according to the displacement of the piston valve. A ventilly type vaporizer has been proposed. Among them, as a device that promotes atomization of fuel and obtains a good mixture of atomization, for example, as shown in Japanese Utility Model Publication No. 4963/1983, filed by the applicant of the present application, there is an inner vent lily and an outer vent lily. However, there is one in which a part of the outer vent ule is formed by a piston valve. In this configuration, a cylindrical inner vent lily with an open main nozzle is integrally formed at the bottom of the intake passage, and a piston valve with a U-shaped tip on the outside of the inner vent lily closes the outer vent lily part at low speeds. A jet needle attached to the tip of the piston valve is inserted into the main nozzle through the inner ventilate.

However, those using a jet needle require high precision in the outer shape of the jet needle, which has the disadvantage of being expensive.

In order to overcome this drawback, the applicant of the present invention filed an application in Utility Model Application No. 146053/1983. This device has an inner vent turret and an outer vent lily, and is the same as the above-mentioned one in that a part of the outer vent lily is made up of a piston valve. When changing the cross-sectional area of the yuri, auxiliary fuel is supplied from the auxiliary fuel nozzle according to the position of the piston valve.It has a simpler configuration compared to conventional carburetors, and can maintain the proper level in all operating ranges. This is to obtain the air-fuel ratio.

In a variable ventilator carburetor with this configuration, auxiliary fuel is supplied from the auxiliary fuel nozzle to the outer ventilate by the displacement of the piston valve, but if the amount of intake air when the piston valve is activated is small, There is also a possibility that the fuel may not be ejected from the auxiliary fuel nozzle, or that the auxiliary fuel may lag behind the operation of the piston valve.

[Problems to be solved by the invention] The invention has been made in view of the above points, and even when the amount of intake air is small when the piston valve is activated, the auxiliary fuel can be easily ejected from the auxiliary fuel nozzle. The purpose is to

[Means for Solving the Problems] In order to achieve the above object of the present invention, an inner vent lily and an outer vent lily are provided in the middle of the intake passage, and a main nozzle for injecting main fuel into the inner vent lily is provided. A part of the wall of the outer vent ule is formed with a piston valve that is displaced by negative pressure in the intake passage, and an auxiliary fuel nozzle is opened in the outer vent ule, and the auxiliary fuel nozzle allows the outer vent to flow from the auxiliary fuel nozzle in accordance with the displacement of the piston valve. In a variable ventilator type carburetor that supplies auxiliary fuel to a ventilator, a groove is formed on the surface of the upstream side of the intake passage of the piston valve from the middle of its length along the sliding direction to the tip, and the groove is formed to prevent the piston valve from operating. The auxiliary fuel nozzle is sometimes positioned within the groove of the piston valve.

[Example] Next, the present invention will be explained based on the drawings.

The attached drawing is a sectional view showing an embodiment of the variable ventilate type carburetor according to the present invention. An intake passage 12 is formed in a main body 10 of the single-barrel carburetor, and an inner vent 14 is provided within the intake passage 12, and a throttle valve 16 is provided downstream of the inner vent ule 14. Fuel to the inner ventilate 14 is injected from the float chamber 18 through a main jet 20, a main fuel passage 22, and a main nozzle 24. An outer vent turret is formed on the outside of the inner vent lily 14 by the inner wall of the intake passage 12 of the main body 10 and the piston valve 26. This piston valve 26
A diaphragm 28 is attached to one end of the diaphragm 28, and the periphery of the diaphragm 28 is fixed to the main body 10. This diaphragm 28 creates a negative pressure chamber 30.
and an atmospheric chamber 32 communicating with the atmosphere. This negative pressure chamber 30 communicates with the intake passage 12 on the downstream side of the piston valve via a through hole 34 formed in the piston valve 26. This piston valve 26 is always biased toward the inner ventilate 14 by a spring 36 installed in the negative pressure chamber 30 .

Apart from the main fuel passage 22, a float chamber 18
An auxiliary fuel nozzle 40 is provided for injecting fuel from the engine into the intake passage 12 via the auxiliary fuel passage 38. The tip of the auxiliary fuel nozzle 40 is located on the outer ventilate upstream of the piston valve 26. That is, the tip of this auxiliary fuel nozzle 40 is located at the piston valve 2 in a low load range or in practical use.
6, and is set to be located near the tip of the piston valve 26 when the piston valve 26 is operated in a medium load range or a high load range.

The above is the configuration of the conventionally proposed variable ventilate type carburetor. In the carburetor with this configuration, since the negative pressure in the negative pressure chamber 30 is small in a low load range or a practical range, the spring 36 causes the piston valve to
6 is pressed toward the inner bench lily 14, and functions as a fixed vent lily (the state shown in FIG. 1). In this state, the auxiliary fuel nozzle 4
Intake air does not flow to the 0 position, and the auxiliary fuel nozzle 4
No fuel is supplied from 0. On the other hand, in the medium load range or high load range, the negative pressure introduced into the negative pressure chamber 30 overcomes the spring 36, actuating the piston valve 26 to change the cross-sectional area of the outer vent lily, and function as a variable vent lily. do. At this time, as the piston valve 26 operates, fuel is injected from the auxiliary fuel nozzle 40 to appropriately adjust the air-fuel ratio in the medium load range and high load range.

In this invention, in addition to the above configuration,
As shown in FIG. 1, a groove 38 is formed on the surface of the piston valve 26 on the upstream side of the intake passage 12 from the middle of its length along the sliding direction to the tip. The tip of the auxiliary fuel nozzle 40 is set to be inserted into the groove 38 when the piston valve 26 is inactive. In addition,
The tip of the auxiliary fuel nozzle 40 is disengaged from the groove 38 when the piston valve 26 is actuated to enter a partial load condition.

In the present invention configured as described above, a groove 38 is formed at the tip of the piston valve 26, and the auxiliary fuel nozzle 40 is positioned within the groove 38. This groove 38 serves to collect air for passage through the outer ventilate. In addition, the opening of this groove 38 is located near the narrowest part of the outer vent ule, and is located at a position where the negative pressure is highest in the outer vent turret. Therefore, even when the piston valve 26 is inactive, if there is a certain amount of intake air, air flows through the groove 38 and fuel is ejected from the auxiliary fuel nozzle 40 located within the groove 38. That is, even if the piston valve 26 is not activated, the auxiliary fuel can be injected by the intake air.

In addition, as shown in FIGS. 2 and 3, the fuel injection port of the auxiliary fuel nozzle 40 is not only the injection port 42 at the tip position, but also a plurality of injection ports 44 near the tip.
may be formed. Note that the fuel injection port of the auxiliary fuel nozzle 40 is configured by closing the axial tip of the auxiliary fuel nozzle 40 (eliminating the injection port 42).
A plurality of auxiliary fuel nozzles 40 may be provided only in the longitudinal direction. In this way, by providing the auxiliary fuel nozzle 40 with a plurality of fuel injection ports 44, the auxiliary fuel can be adjusted more finely.

Moreover, if the size of the plurality of fuel injection ports 44 is set to increase toward the tip of the auxiliary fuel nozzle 40, the amount of auxiliary fuel can be adjusted more finely.

Note that when the piston valve 26 is in the non-operating state, the one located away from the tip of the pipe among the plurality of injection ports 44 is positioned outward of the groove 38 of the piston valve 26, and is used as an auxiliary injection port. This is designed to prevent fuel delays.

[Effects of the invention] As described above, according to the variable ventilator carburetor according to the invention, a groove is formed at the tip of the piston valve, and the auxiliary fuel nozzle is positioned in the groove when the piston valve is not activated. This makes it easier to inject auxiliary fuel even when the amount of intake air is small when the piston valve is not activated.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view showing an embodiment of a variable ventilee type carburetor according to the present invention, FIG. The figure is a plan view of FIG. 2. 12...Intake passage, 14...Inner vent lily, 24...Main nozzle, 26...Piston valve, 38...Auxiliary fuel passage, 40...Auxiliary fuel nozzle, 42...Fuel injection port, 44...Fuel injection port.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) It has an inner vent turret and an outer vent lily in the middle of the intake passage, the main nozzle for injecting the main fuel is opened in the inner vent lily, and one part of the wall of the outer vent lily is opened. part is formed by a piston valve that is displaced by negative pressure in the intake passage,
In a variable vent ule type carburetor, an auxiliary fuel nozzle is opened in the outer vent ule and auxiliary fuel is supplied from the auxiliary fuel nozzle to the outer vent ule according to the displacement of the piston valve. A variable ventilee type carburetor, characterized in that a groove is formed from the middle of its length along the moving direction to the tip, and the tip of the auxiliary fuel nozzle is positioned within the groove when the piston valve is not in operation. (2) The variable ventilee type carburetor according to claim 1, wherein a plurality of fuel injection ports of the auxiliary fuel nozzle are formed near the tip thereof. (3) The variable ventilate carburetor according to claim 2, wherein the size of the plurality of fuel injection ports gradually increases toward the tip injection port.