JPH0746755Y2 - Vaporizer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a carburetor for an engine, such as a small power atomizer or a generator, which operates at a constant speed.

<Prior art> A small power atomizer or an engine that operates at a constant speed, such as a generator, that does not have a governor mechanism, has a throttle valve opening of a carburetor fixed at a constant speed to rotate the engine at a constant speed. There is.

Further, in order to protect equipment such as a pump or a dynamo and reduce noise, this type of engine is set to a low normal rotation speed, and accordingly, the throttle valve opening is reduced.

However, when the engine is started, it is difficult to start it even if the choke valve is closed if the throttle valve opening is small. Therefore, it is necessary to increase the throttle valve opening to some extent. A mechanism is adopted in which the throttle valve opening is increased when the choke valve is closed by linking with a link or wire.

<Problems of the Prior Art> In the above-mentioned conventional example, if the choke valve and the throttle valve are not properly synchronized, the engine demand and the air-fuel ratio are deviated, and the equipment is damaged due to engine stall or engine speed increase. It was dangerous and this setting was difficult and annoying.

Further, the interlocking of the choke valve and the throttle valve by the conventional link or wire has a drawback that the carburetor becomes large.

The present invention automatically adjusts the throttle valve opening so that the air-fuel ratio is always appropriate by driving the throttle valve with intake negative pressure, facilitating the setting of this seed carburetor and making it compact. The purpose is to provide a vaporizer.

<Technical Means for Solving Problems> A throttle valve that is biased in the opening direction of the intake passage, and a pressure receiving portion that receives negative intake pressure to move the throttle valve in the closing direction of the intake passage are provided. It is characterized in that the air intake of the air chamber formed on the back surface of the portion is opened in the intake passage between the choke valve and the venturi.

<Operation> While the engine is stopped, the throttle valve is fully open.

At the downstream of the choke valve, the negative pressure in the intake passage becomes almost uniform, and the atmospheric pressure chamber and the negative pressure chamber have the same pressure, so that the throttle valve is kept fully open. Therefore, a large amount of fuel is supplied to the engine, and the engine starts up well.

When the choke valve is opened after the engine is started, the negative pressure in the atmosphere chamber gradually decreases, and accordingly, the throttle valve moves to reduce the opening area of the intake passage.

When the choke valve is fully opened, the atmospheric pressure becomes almost atmospheric pressure, the throttle valve is closed to the specified opening, and the engine operates at a constant speed.

<Embodiment> An embodiment of the present invention will be described below with reference to the drawings. An carburetor 1 is provided with an intake passage 4 penetrating the carburetor body 2, and a downstream side of the intake passage 3 is connected to an intake port of an engine (not shown). In the intake passage 3,
A piston type throttle valve 5 which is normally urged upward by a spring 4 and held in a fully open state is provided, and a pressure receiving portion 6 is provided above the throttle valve 5 constantly or separately from the throttle valve 5. ing. An atmosphere chamber 7 and a negative pressure chamber 8 are formed above and below the pressure receiving portion 6, and a negative pressure is applied to the negative pressure chamber 8 from a negative pressure inlet 18 opening downstream of the venturi 12 via a check valve 9. In addition to being actuated, the air chamber 7 has an intake passage 3 between the choke valve 11 and the venturi 12.
Atmosphere is introduced from the air intake 13 opened at. The check valve 9 need not be provided in particular, but the vibration of the throttle valve 5 due to the pulsating component of the intake negative pressure is suppressed and the throttle is used when the engine speed is reduced due to a high load and the negative pressure in the intake passage 3 is weakened. It is desirable to provide it to prevent the valve 5 from opening.

The throttle valve 5 is provided with a jet needle 14 projecting downward, and the jet needle 14 is inserted into a needle jet 15 opening at the bottom wall of the intake passage 3, and the intake passage is formed in the gap between the jet needle 14 and the needle jet 15. The fuel sucked into 3 is measured.

Reference numeral 16 is an adjusting screw for setting the bottom dead center of the throttle valve 5 for adjusting the normal engine speed, and 17 is an air hole formed in the choke valve.

Next, the operation of the above embodiment will be described.

When the engine is cranked with the choke valve 11 fully closed, the negative pressure in the intake passage 3 becomes substantially uniform downstream of the choke valve 11 and the atmosphere chamber 7 and the negative pressure chamber 8 have the same pressure. The throttle valve 5 is kept in a fully open state, and a large amount of fuel sucked from the needle jet 15 and the air flowing in from the air hole 17 of the choke valve 11 generate a rich air-fuel mixture for starting, which is supplied to the engine. .

When the engine speed increases and the amount of air flowing in from the air hole 17 of the choke valve 11 increases, the negative pressure in the negative pressure chamber 8 becomes different between the upstream side and the downstream side of the venturi 12. Since the negative pressure in the atmosphere chamber 7 becomes smaller than that in the above, the throttle valve 5 is lowered a little by this, and the rotation of the engine is reduced to prevent the equipment connected to the engine from being damaged.

When the choke valve 11 is gradually opened as the engine warms up, the negative pressure acting on the atmosphere chamber 7 decreases accordingly. Therefore, the throttle valve 5 corresponds to the opening degree of the choke valve 11. Gradually descend to maintain proper engine speed and air-fuel ratio.

When the choke valve 11 is fully opened, the atmospheric pressure near the atmospheric air intake 13 becomes almost atmospheric pressure, the throttle valve 5 contacts the adjusting screw 16 and maintains the specified opening, and the engine operates at a constant speed.

FIG. 3 shows an embodiment in which the present invention is applied to a carburetor equipped with a butterfly type throttle valve.
12 A throttle valve 20 disposed in the intake passage 3 downstream is connected to a diaphragm type drive device 21, and an air intake 22 of this drive device 21 is opened in the intake passage 3 between the choke valve 11 and the venturi 12. , Negative pressure inlet 23 throttle valve
20 The intake passage 3 is opened downstream. Further, 24 is a diaphragm, 25 is a negative pressure chamber, and 26 is an atmospheric chamber.

<Effects of the Invention> As described above, according to the present invention, the throttle valve that is biased in the opening direction of the intake passage and the pressure receiving portion that receives the intake negative pressure and moves the throttle valve in the closing direction of the intake passage are provided. Prepare,
By opening the atmosphere intake of the atmosphere chamber formed on the back surface of the pressure receiving portion in the intake passage between the choke valve and the venturi, the intake passage between the choke valve and the venturi that changes according to the opening degree of the choke valve. Since the pressure can be introduced to the atmosphere chamber and an appropriate throttle valve opening corresponding to the choke valve opening can be obtained, it is possible to supply an air-fuel mixture having an air-fuel ratio that meets the engine's requirements, and to operate the engine smoothly. It can be done and the setting of the carburetor is easy.

Further, the carburetor can be made compact as compared with the conventional mechanism in which the choke valve and the throttle valve are connected by a link or a wire.

[Brief description of drawings]

1 is a 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 sectional view showing another embodiment of the present invention. 3 ... Intake passage, 5 ... Throttle valve, 6 ... Pressure receiving portion, 7 ...
Atmosphere chamber, 8 ... Negative pressure chamber, 13 ... Atmosphere intake.

Claims (1)

[Scope of utility model registration request] 1. A throttle valve urged in the opening direction of an intake passage, and a pressure receiving portion for receiving a negative pressure of intake air to move the throttle valve in the closing direction of the intake passage, which is formed on the back surface of the pressure receiving portion. A carburetor characterized in that the atmosphere intake of the atmosphere chamber is opened in the intake passage between the choke valve and the venturi.