JPH0720366Y2 - Diaphragm vaporizer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a diaphragm type carburetor used as a carburetor for engines operated in various postures, for example, engines for brush cutters.

(Prior Art) Conventionally, a diaphragm-type carburetor used as a carburetor for an engine for a brush cutter is provided with a sensing chamber provided at a lower portion of a carburetor main body and having a bottom wall formed of the diaphragm, and a fuel from the sensing chamber. A main nozzle that faces the intake passage through an adjustment orifice, a fuel passage from a fuel tank that communicates with the sensing chamber, a fuel pump that is provided in the middle of the fuel passage and that is operated by the operating pressure of the engine, and the fuel passage The control valve is provided at the inlet of the sensing chamber and is interlocked with the diaphragm via a lever.The fuel in the sensing chamber is sucked into the intake passage from the main nozzle, and the control valve interlocks with the diaphragm that moves upward accordingly. The fuel passage is opened to supply the same amount of fuel as the sucked fuel into the sensing chamber.

(Problems of the prior art) However, since the brush cutter takes various postures during work, when the diaphragm type carburetor having the above-mentioned configuration is used in the inverted posture with respect to the established posture of the engine, it is accompanied by the inverted posture of the engine. As a result, the fuel in the sensing chamber flows toward the main nozzle due to gravity, and the amount of fuel flowing out from the main nozzle increases accordingly. As a result, the concentration of the air-fuel mixture produced in the intake passage becomes rich and the engine speed decreases. In particular, when the engine rotates at a low speed such as idling rotation, there is a drawback that engine stall occurs.

(Technical Means for Solving Problems) A technical means for solving the above problems is to provide a sensing chamber having a bottom wall formed of a diaphragm in a lower portion of a carburetor main body, and fuel in the sensing chamber. In the diaphragm type carburetor configured to be ejected into the intake passage through the main nozzle, the main nozzle accommodates a ring body that moves by its own weight when the carburetor is in an inverted position and narrows the fuel hole of the main nozzle. Especially.

(Specific Description of the Invention) The present invention will be specifically described below with reference to the drawings.

In FIG. 1, reference numeral 1 is a diaphragm type carburetor, and an intake passage 3 is provided in the main body 2. A sliding throttle valve 4 faces the inside of the intake passage 3 from above so that it can move back and forth. A main nozzle 5 is opened in a bottom wall of the intake passage 3 below the sliding throttle valve 4, and a lower end of the main nozzle 5 communicates with a sensing chamber 7 via a fuel adjusting orifice 6. A jet needle 8 is suspended from the sliding throttle valve 4, and the jet needle 8 is inserted in the main nozzle 5.

Reference numeral 9 is a fuel pump which operates by the pulsation of the engine. The fuel pump 9 includes a diaphragm 10 and a pair of check valves 11,
It is a well-known diaphragm pump having 12. In a diaphragm chamber 13 formed on one side of the diaphragm 10, a pressure passage 14 for introducing an operating pressure having an engine pulsation for operating the diaphragm 10, for example, a crank chamber pressure in a two-cycle engine.
Are connected. Further, fuel supply passages 16 and 17 are connected to the pump chamber 15 formed on the other side of the diaphragm 10 via the check valves 11 and 12, respectively. One fuel supply passage 16 is connected to the fuel tank 18 via a connection port 19 to the fuel tank 18, and the other fuel supply passage 17 is connected to the sensing chamber 7. Therefore, in the operating state of the internal combustion engine, the fuel pump 9 moves from the fuel tank 18 to the tank.
The fuel in 18 is sucked into the pump chamber 15 via one check valve 11 and is pumped to the sensing chamber 7 via the other check valve 12.

The sensing chamber 7 has a bottom wall formed by a diaphragm 20. At the inlet of the sensing chamber 7 of the fuel supply passage 17, there is provided a fuel valve 21 which operates in order to connect or disconnect the passage 17 in relation to the diaphragm 20, that is, to connect or disconnect the communication between the fuel pump 9 and the sensing chamber 7. Has been. A lever having a support shaft 22 between the fuel valve 21 and the diaphragm 20.
23 are arranged. The lever 23 is connected to the fuel valve 21 on one side and the other side is connected to the diaphragm 20 about the spindle 22. Therefore, when a strong negative suction pressure acts on the sensing chamber 7 through the main nozzle 5, the diaphragm 20 causes the diaphragm 23 to introduce fuel from the fuel pump 9 through the passage 17 into the sensing chamber 7. The fuel valve 21 is held in the open position of the fuel supply passage 17 via the.
Further, by introducing fuel into the sensing chamber 7, the sensing chamber 7
When the strong negative pressure of the fuel valve 21 disappears, the fuel valve 21 is urged to shut off the passage 17 by the biasing force of the compression spring 24 engaging the lever 23 so as to prevent the fuel from being introduced into the sensing chamber 7. To be done.

Reference numeral 25 denotes a fuel jet formed in the main nozzle 5, and the amount of fuel flowing out from the main nozzle 5 is controlled by a gap formed by the shed 25 and the jet needle 8. A fuel chamber 26 is provided below the fuel jet 25, and a side wall of the fuel chamber 26 is provided with a fuel hole 27 communicating with the fuel adjusting orifice 6. Therefore, the fuel flowing into the fuel chamber 26 through the fuel adjusting orifice 6 is
It flows out from the main nozzle 5 to the intake passage 3 through a gap formed by the jet needle 8 and the fuel jet 25.

An annular body 28 is slidably accommodated in the fuel chamber 26. Jet holes 29 are provided on the side wall of the ring body 28,
A concave groove 30 is formed on the outer peripheral surface of the ring body 28 in which the jet hole 29 is formed.
Is provided. The annular body 28 is seated on the bottom of the fuel chamber 26 by its own weight when the carburetor is in the established posture, and moves to the upper side of the fuel chamber 26 when the carburetor is in the inverted posture and the stopper 31 provided on the upper portion of the chamber 26. Abut, fuel hole 27 and jet hole
Match 29. Therefore, when the carburetor is in the inverted position, the flow rate of fuel is regulated by the jet hole 29.

According to the present invention configured as described above, when the carburetor is in the established posture, the ring member 28 is seated on the bottom portion of the fuel chamber 26 by its own weight, and the fuel hole 27 is opened. The fuel flows out with the fuel outflow amount of.

When the carburetor is in the inverted posture, the ring body 28 moves to the upper part of the fuel chamber 26 by its own weight, and the jet hole 29 formed in the ring body 28 is aligned with the fuel hole 27 of the main nozzle 5. As a result, the flow rate of fuel flowing from the fuel hole 27 into the main nozzle 5 is regulated by the jet hole 29, and the flow rate is reduced. Therefore, if the size of the jet hole 29 is set according to the degree of increase in the amount of fuel outflow associated with this inverted posture, the air-fuel mixture of the optimum concentration is always automatically generated corresponding to this inverted posture. can do.

2 and 3 are longitudinal sectional views of the essential parts of another embodiment of the present invention.

FIG. 2 shows that a fuel hole 32 is provided above the stopper 31 formed in the fuel chamber 26 of the main nozzle 5, and a fuel hole 27 is provided below the stopper 31, and the annular body 28 serves as the stopper when the carburetor is in the inverted position. The fuel flow rate in this inverted position is reduced by abutting against the above and closing only the lower fuel hole 27.

FIG. 3 shows that the ring 33 is the fuel jet when the carburetor is in the inverted position.
It is constructed so as to contact the lower end of 25 to close the inside of the main nozzle 5, and the ring body 33 is provided with a jet hole 34 to reduce the amount of fuel outflow from the main nozzle 5. ing. In this embodiment, since the ring body 33 is pushed by the jet needle 8 when the sliding throttle valve 4 is in a low and medium opening degree, the inside of the main nozzle 5 is not blocked and the fuel outflow amount is not reduced in this rotation range. Since the ring body 33 is not pushed by the jet needle 8 when the dynamic throttle valve 4 is at a high opening degree, the ring body 33 can block the main nozzle 5 and reduce the fuel outflow amount. Therefore, this configuration may be used when it is necessary to prevent the engine speed from being lowered in the inverted posture only when the engine speed is high.

(Effect of the Invention) As described in detail above, according to the present invention, the main nozzle of the carburetor accommodates the ring body that moves by its own weight, and the ring body squeezes the fuel hole when the carburetor is in the inverted position. Since the amount of fuel flowing out from the nozzle is automatically reduced, the air-fuel mixture concentration can be optimized even in the inverted posture, and the engine rotation drop and engine stall in the inverted posture can be prevented.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing an embodiment of the present invention, and FIGS. 2 and 3 are vertical cross-sectional views of essential parts showing another embodiment of the present invention. 1 ... Diaphragm carburetor, 3 ... Intake passage, 5 ...
Main nozzle, 7 ... Sensing chamber, 20 ... Diaphragm, 26
…… Fuel chamber, 27 …… Fuel hole, 28 ・ 33 …… Ring, 29 ・ 32 ・
34 ... Jet hole.

Claims (1)

[Scope of utility model registration request] 1. A diaphragm type carburetor having a sensing chamber having a bottom wall formed of a diaphragm at a lower portion of a carburetor body and ejecting fuel in the sensing chamber into an intake passage through a main nozzle. A diaphragm type carburetor, characterized in that a ring-shaped body that moves by its own weight when the carburetor is in an inverted posture and squeezes a fuel hole of the main nozzle is accommodated in the main nozzle.