JP2512853Y2 - Vaporizer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a carburetor in which a piston valve is arranged in an intake passage so that the piston valve can move back and forth and the effective diameter of the intake passage is controlled by the movement of the piston valve.

<Prior Art> Conventionally, in the above vaporizer, as shown in FIG. 4, a groove 31 is formed on the bottom surface of the piston valve 30 from the upstream peripheral edge to the downstream peripheral edge, and the cross-sectional area gradually decreases from upstream to downstream.
This groove 31 allows the nozzle to open when the piston valve is low
There is one that concentrates the intake air around 32 to improve the atomization of fuel. (Refer to Japanese Utility Model Publication No. 50-18017) <Problems of the prior art> However, when the intake air is concentrated near the nozzle 32 by the groove 31, conversely, the blowback of the fuel generated by the pulsation of the engine is also in this groove 31. Since they collect, the impurities 34 mixed in the fuel are likely to adhere to the jet needle 33 and the nozzle 32 arranged in the groove 31, and the adhesion of the impurities 34 causes the fuel injection amount to vary and the rotation of the engine to become unstable. .

The present invention provides a carburetor that has good atomization at a low opening of a piston valve, does not deposit impurities at a nozzle and a jet needle, and has stable engine rotation at this opening. To aim.

<Means for Solving the Problems> The present invention is characterized in that the bottom surface of the throttle valve is provided with a cutout portion extending from the upstream side to at least the side surface of the jet needle and shallower than the groove.

<Operation> According to the above configuration, the air flowing in from the air cleaner is supplied to the engine through the groove. Further, a part of this air also flows into the groove from the side surface of the jet needle through the cutout portion. Therefore, the fuel blown back from the engine side diffuses into the notch near the jet needle,
Impurities in the fuel are less likely to adhere to the jet needle and nozzle. Moreover, since the notch is formed shallower than the groove, the flow velocity of the air flowing in the groove remains high, and the atomization of the fuel at a low opening degree is hardly deteriorated by the notch.

<Embodiment> An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention, and FIG. 2 is a sectional view taken along the line AA of FIG.

An carburetor 1 is provided with an intake passage 3 penetrating the body 2. The upstream side of the intake passage 3 is connected to an air cleaner (not shown), and the downstream side is connected to an intake port of an engine (not shown). . Further, a guide cylinder 4 is connected to the intake passage 3, a piston valve 5 is slidably accommodated in the guide cylinder 4, and the effective diameter of the intake passage is changed by the movement of the piston valve 5. A nozzle 6 is opened in the intake passage wall below the piston valve 5, and the other end of the nozzle 6 is connected to a fuel chamber (not shown). A jet needle 7 is attached to the piston valve 5 so as to project downward and the tip side is inserted into the nozzle. Further, a groove 8 is provided on the lower surface of the piston valve 5 through the jet needle 7, from the upstream side peripheral edge to the downstream side peripheral edge, and the cross-sectional area gradually decreases from the upstream side to the downstream side. When the opening is low, the intake negative pressure is concentrated in the opening of the nozzle 6 by the groove 8 to improve the suction and atomization of the fuel. The above is a piston valve type carburetor generally used conventionally.

The present invention further includes the groove 8 extending from the upstream side to the side surface of the jet needle 7 or immediately after the lower edge of the piston valve 5.
A shallower notch 10 is provided so that a part of the air flowing from the air cleaner is made to flow from the side surface of the jet needle 7 into the groove 8 by the notch 10. Therefore, the fuel blown back from the engine side diffuses into the notch 10 in the vicinity of the jet needle, and the impurities in the fuel are less likely to adhere to the jet needle 7 and the nozzle 6. Moreover, since the notch 10 is formed shallower than the groove 8, the flow velocity of the air flowing in the groove 8 is still increased.
Due to 10, the atomization of fuel at low opening hardly deteriorates.

FIG. 3 shows notches 11 and 12 on the bottom surface of the piston valve 5 from the air cleaner side to the jet needle 7 side of the groove 8.
The jet needle 7 is provided through the notches 11 and 12.
Air is made to flow through the parts, and the blown back fuel is dispersed in the notches 11 and 12 to prevent impurities contained in the fuel from adhering to the jet needle 7.

<Effects of the Invention> As described in detail above, according to the present invention, the bottom surface of the piston valve that is provided in the intake passage so as to move back and forth has a cross section that gradually extends from the upstream peripheral edge to the downstream peripheral edge and from the upstream side to the downstream side. In a carburetor that is provided with a groove that is small and that concentrates negative pressure near the nozzle to improve fuel atomization at the time of low opening of the piston valve by this groove, at least the jet from the upstream side on the bottom surface of the throttle valve. Since the notch that reaches the side of the needle and is shallower than the groove is provided, the fuel blown back through the groove at the time of low opening of the piston valve is diffused in the notch and impurities in the fuel adhere to the jet needle. As a result, it is possible to stabilize the operation of the engine when the throttle valve has a low opening.

[Brief description of drawings]

1 is a vertical sectional view showing an embodiment of the present invention, FIG. 2 is a sectional view taken along the line AA of FIG. 1, and FIG. 3 is a vertical sectional view showing another embodiment of the present invention. The figure is a longitudinal sectional view showing a conventional example. 3 ... Intake passage, 5 ... Piston valve, 6 ... Nozzle, 7 ...
… Jet needles, 8 …… grooves, 10/11/12 …… notches.

Claims (1)

(57) [Scope of utility model registration request] 1. A groove extending from an upstream side peripheral edge to a downstream side peripheral edge and having a cross-section gradually decreasing from upstream to downstream is provided on a bottom surface of a piston valve which is provided to be movable back and forth in an intake passage.
In this carburetor configured to concentrate the intake negative pressure near the jet needle and the nozzle to improve the atomization of fuel at the time of low opening of the piston valve by this groove, on the bottom surface of the piston valve, from upstream to at least the side surface of the jet needle. A vaporizer characterized in that a notch portion shallower than the groove is provided.