JPS6183474A - Starting device of diaphragm type carburetor - Google Patents

Abstract

PURPOSE:To easily feed fuel by the pressure of air to a carburetor when an engine is started, by providing a priming pump in a fuel route from a tank to a diaphragm chamber while a fuel reservoir chamber, which stores air in its upper part, and compressing the air when the fuel is forced to be fed into the fuel reservoir chamber at priming time. CONSTITUTION:Fuel is supplied from a tank 17 through a priming pump 23, pump chamber 14 and a fuel valve 19 to a carburetor 1 having a diaphragm 18. The fuel in the tank 17 is allowed to flow into a diaphragm chamber 7 through the above described route by actuating the priming pump 23 before an engine is started, but here the fuel, being allowed to flow also into a fuel reservoir chamber 25 initially filled with air and compressing the air, is returned to the tank by opening a check valve 27 if a pressure of the air increases to a predetermined value or more. If the engine is started from this condition, the fuel in the fuel reservoir chamber 25, being forced to be fed by an air layer 24, is surely supplied to the diaphragm chamber 7 when its fuel is supplied.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a starting device for a diaphragm carburetor.

(Conventional Technique #t) Diaphragm type carburetors that can be used in engines such as brush cutters generally require the sensing chamber to be filled with fuel before starting, so the fuel supply passage leading to the fuel tank and fuel valve must be At the same time, a priming pump is installed in the sensor chamber, and the fuel valve is opened manually using a tickler, and at the same time the air vent no-fuel overflow valve is opened.In this state, the priming pump is operated to flow fuel into the sensing chamber, and the sensing chamber is opened. A starting device has been proposed that can detect when the carburetor is full of fuel from the fuel flowing out of the carburetor from a portion of the overflow.

(Problems with the Prior Art) However, with the above-mentioned starting device, it is necessary to operate both the priming pump and the ticker when starting, which requires both hands and is cumbersome to handle.

Furthermore, if the overflowing fuel is discharged to the outside of the carburetor, there is a risk of a fire occurring if, for example, the discharged fuel adheres to dry grass or the like and cigarettes are thrown there.

(Means for solving the problem) The technical means taken to solve the above problem is to use a fuel pump that is activated by the pulsation of an internal combustion engine, and to supply fuel from the fuel pump to the main nozzle at a constant pressure. A diaphragm carburetor comprising a diaphragm defining a sensing chamber for directing the fuel, and a fuel valve operating in association with the diaphragm to connect and disconnect communication between the fuel pump and the sensing chamber. A priming pump is disposed in the middle of a fuel supply passage connecting the priming pump, and the fuel supply passage between the priming pump and the fuel valve includes a fuel reservoir chamber having an air layer above and a fuel supply chamber upstream of the priming pump. A check valve that opens at a fuel pressure lower than the opening pressure of the fuel valve is disposed in the return passage.

(Function) When the priming pump is operated when starting the engine, the fuel in the fuel tank can be pumped to the carburetor, but since the carburetor needle valve at the entrance of the sensing chamber is closed, the fuel is pumped into the fuel reservoir chamber. be done. Since an air layer is completely formed above the fuel reservoir, the fuel compresses the air layer and flows into the fuel reservoir. Eventually, when the fuel pressure in the fuel reservoir reaches a certain level or higher, the check valve opens and returns the fuel to the fuel tank. Therefore, a constant amount of fuel remains in the fuel storage chamber.

When the engine recoils, the engine's negative pressure momentarily acts on the sensing chamber, pulling up the diaphragm and opening the fuel valve. Then, the fuel accumulated at a constant pressure in the fuel reservoir chamber is forced into the sensing chamber, and the fuel chamber is filled with fuel.

(Detailed Description of the Invention) FIG. 1 is a longitudinal cross-sectional view showing a starter device of the present invention, and FIGS. 2 and 3 are longitudinal cross-sectional views of essential parts showing an embodiment of the present invention.

In FIG. 1, 1 is a diaphragm type carburetor, and this main body 2 is provided with an intake passage 3. A sliding throttle valve 4 faces into the intake passage 3 from above and can move forward and backward. A main nozzle 5 opens at the bottom wall of the intake passage 3 below the sliding throttle valve 4, and the lower end of the main nozzle 5 communicates with the sensing chamber 7 via a fuel adjustment orifice 6. A jet needle 1 is suspended from the sliding throttle valve 4, and seven balls of the jet needle are inserted into the main nozzle 5.

8 is a fuel pump operated by engine pulsation. The fuel pump 8 includes a diaphragm 9 and a pair of check valves 10.
．． 11 is a conventionally well known diaphragm pump. A pressure passage 13 is connected to a diaphragm chamber 12 formed on one side of the diaphragm 9 to introduce the pulsating operating pressure of the engine, for example, the crank chamber pressure in a two-stroke engine, in order to operate the diaphragm 9. ing. In addition, the pump chamber 14 formed on the other side of the diaphragm 9 includes the check valve 10.1.
1 are connected to the fuel tank 17, and the other fuel supply passage 16 is connected to the sensing chamber 7. Therefore, when the internal combustion engine is in operation, the fuel pump 8 sucks the fuel in the tank 17 into the pump chamber 14 through one check valve 10, and transfers this fuel to the other check valve. 11 to the sensing chamber 7.

The sensing chamber 7 has a bottom wall formed by a diaphragm 18. The sensing chamber 7 of the fuel supply passage 16 is provided with a fuel valve 19 which operates in conjunction with the diaphragm 18 to disconnect the passage 16, that is, to disconnect the communication between the fuel pump 8 and the sensing chamber 7. It is being A support shaft 2 is provided between the fuel valve 19 and the diaphragm 18.
Shihe-21 with 0 has been placed. The lever 21
One side is connected to the fuel valve 19 around the support shaft 20, and the other side is connected to the diaphragm 18. Therefore, when a strong negative intake pressure acts on the sensing chamber 7 through the main nozzle 5, the diaphragm 18 moves the lever 21 to prevent fuel from the fuel pump 8 from entering the sensing chamber 7 through the passage 16. The fuel valve 19 is held in the open position of the fuel supply passage 16 via the . Further, when the strong negative pressure in the sensing chamber 7 disappears due to the introduction of fuel into the sensing chamber 7, the fuel valve 19 is operated by the biasing force of the compression spring 22 that engages the lever 21 to inject the fuel into the sensing chamber 7. The passageway 16 is biased to block the passageway 16 to prevent the introduction of.

A priming pump 2 is provided in the middle of the fuel supply passage 15 for supplying fuel into the sensing chamber 7 when starting the engine.
3 are provided. A fuel reservoir chamber 25 having an air layer 24 formed therein is connected to the fuel supply passage 15 between the priming pump 23 and the fuel pump 8. On the other hand, this fuel supply passage 15 and the fuel supply passage 15 or fuel tank 17 on the upstream side of the priming pump 23 communicate with each other through a return passage 26.
6, the opening pressure of the fuel valve 19 (approximately 0,4 k
g/cTn') slightly lower than the fuel pressure (0.2~0.3
A check valve 27 is provided which opens when the engine temperature reaches 1 kg. Therefore, when the engine is started, if the priming pump 23 is operated, the fuel in the fuel tank 17 is pumped through the fuel pump 8 to the fuel valve 19 in the sensing chamber 7, but when the engine is stopped, The fuel valve 19 of the sensing chamber 7 is connected to the fuel supply passage 1 so as to prevent the introduction of fuel into the sensing chamber 7 by the biasing force of the compression spring 22.
6 is shut off, the fuel flows into the fuel reservoir chamber 25. Air accumulates in the upper part of the fuel storage chamber 25 to form an air layer 24, and the fuel is compressed and fed into the chamber 25 under pressure. Eventually, when the fuel pressure in the chamber 25 becomes equal to or higher than the opening pressure of the check valve 27, the check valve 27 opens and the fuel is returned to the fuel tank 17, and the fuel accumulates in the chamber 25 at a constant pressure. .

When the engine is coiled in this state, the intake negative pressure of the engine momentarily acts in the sensing chamber 7 through the main nozzle 5, pulling up the diaphragm 18 and opening the fuel valve 19, thereby opening the fuel supply passage 16 and the sensing chamber 7. Communicate. Then, the fuel remaining at a constant pressure in the fuel reservoir chamber 25 is transferred to the fuel pump 8.
The fuel is then pressure-fed into the fuel chamber 7, and the fuel chamber 7 is quickly filled with fuel.

Furthermore, if a transparent window 28 is provided on the side of the fuel reservoir chamber 25 as shown in FIG. If you stop the priming operation when the fuel oil level has risen to the specified level, you will not have to perform unnecessary priming operations.

FIG. 3 shows a further improvement of the embodiment shown in FIG. 2, in which a float 29 is provided in the fuel reservoir chamber 25.

That is, by checking the fuel oil level in the chamber 25 using the float 29 from the outside of the carburetor, it is made easier to check the fuel oil level.

(Effects of the Invention) As described above, according to the present invention, when starting the engine, the fuel pumped by the priming pump is stored in the fuel reservoir chamber connected to the fuel supply passage in a compressed state, Since the fuel in the fuel reservoir chamber is immediately pumped into the sensing chamber by one coil operation, there is an advantage that the starting operation can be easily performed with one hand, making handling extremely easy.

In addition, when the priming pump is operated, the excess fuel that is sent from the fuel reservoir chamber to the return passage via the check valve flows into the fuel tank again, and the excess fuel is not completely discharged to the outside of the carburetor, so the fuel is vaporized. The above-mentioned danger due to leakage outside the vessel has been eliminated.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view showing an embodiment of the present invention, and FIGS. 2 and 3 are longitudinal cross-sectional views of essential parts showing other embodiments of the present invention. 7... Sensing chamber, 8... Fuel pump, 15/16...
-Fuel supply passage, 17...Fuel tank, 18...Diaphragm, 19...Fuel valve, 23...Priming pump, 24...Air layer, 25...Fuel reservoir chamber, 2
6...Return passage, 27...Check valve, 28.
...Transparent window, 29...Float. Patent applicant: Tikei Vaporizer Co., Ltd. Representative: Tadao Kobayashi Figure 2 Figure 3

Claims (3)

[Claims] (1) a fuel pump operated by the pulsation of an internal combustion engine; a diaphragm defining a sensing chamber for directing fuel from the fuel pump to a main nozzle at a constant pressure; and a fuel pump operated in conjunction with the diaphragm; and a fuel valve that disconnects communication with the sensing chamber, a priming pump is disposed in the middle of a fuel supply passage connecting the fuel valve and the fuel tank, and the priming pump and the fuel valve are connected to each other. A fuel storage chamber having an air layer at the top and a return passage communicating with a fuel supply passage or a fuel tank upstream of the priming pump are connected to a fuel supply passage between the priming pump and the fuel valve. A starting device for a diaphragm carburetor, characterized in that it is equipped with a check valve that opens at a fuel pressure lower than the valve opening pressure of the diaphragm carburetor. (2) The starting device for a diaphragm carburetor according to claim 1, characterized in that a transparent window is provided on a side of the fuel reservoir chamber. (3) The starting device for a diaphragm type carburetor according to claim 2, further comprising a float in the fuel reservoir chamber.