JPS6275058A - Tickler device for diaphragm type carburetor - Google Patents

Abstract

PURPOSE:To feed fuel quickly to a carburetor thus to improve the starting performance by communicating the metering chamber of a diaphragm type carburetor with the atmosphere thereby feeding pressurized air into the atmospheric pressure chamber at start while opening a gate valve. CONSTITUTION:A tube 51 opened to the atmosphere is communicated through a gate valve 63 with the metering chamber 16 of a diaphragm type carburetor while a pressurized air supply path 34 communicated with a manual pump 36 is communicated with an atmospheric pressure chamber 62 and a bellows 33 is branched from the pressurized air supply path 34 to enable function of the gate valve 63. Upon operation of a manual pump 40 at start of engine, the pressurized air will invert a diaphragm 11 to open a valve 10 while the bellows 33 will open the gate valve 63 to open the metering chamber 16 to the atmosphere. When the interior of a tank 1 is heated, fuel is pressure fed through a tube 9 into the metering chamber by means of the steam pressure to exhaust the inner steam and to feed the fuel thus to start immediately.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a tickler device of a diaphragm carburetor for an internal combustion engine.

[Prior Art] Engines whose working postures change, such as chainsaws and brush cutters, are equipped with diaphragm-type carburetors. This type of diaphragm carburetor uses a fuel pump driven by pulsating pressure in the crank chamber of a two-stroke engine;
It includes a metering chamber that has a passage communicating with the fuel injection port and is defined by a diaphragm, and an inflow valve that introduces fuel pumped from the fuel tank by a fuel pump into the metering chamber.

In normal operation, when fuel in the metering chamber is drawn into the engine through the fuel nozzle, the inlet valve opens due to negative intake pressure acting on the diaphragm, and fuel is intermittently replenished from the fuel pump. Therefore, while the engine is in operation, a predetermined amount of fuel is retained in the metering chamber regardless of the attitude of the engine, and an appropriate amount of fuel is supplied to the engine depending on the operating state of the engine.

However, when restarting the engine after full-load operation, there is not enough fuel stored in the metering chamber, making it difficult to start the engine. Even if the engine starts, the metering chamber is not filled with liquid fuel, which may cause a temporary fuel shortage, resulting in the engine stopping immediately or poor acceleration after starting, making smooth operation difficult. becomes difficult to maintain. This is because when the engine is stopped, the fuel nozzle and the metering chamber communicating with it are filled with steam fuel due to the heat of the engine body and direct sunlight, and the air-fuel mixture supplied to the engine becomes diluted.

As a solution to this problem, a manual suction pump is conventionally provided between the fuel tank and the metering chamber, as disclosed in U.S. Pat. It has been proposed to replenish fuel from the fuel tank to the metering chamber using a manual suction pump, and then crank and start the engine. However, in structures such as chainsaws, where the fuel tank is housed in the fuselage and the carburetor is placed in a narrow space near the cylinder, the entire fuel system becomes hot, and the fuel sucked by the suction pump flows into the metering chamber. The liquid fuel vaporizes and becomes vapor fuel before flowing into the metering chamber, resulting in a situation where the liquid fuel is not sufficiently supplied to the metering chamber.

In such a case, the engine cannot be started unless the suction pump is operated many times and the fuel system is cooled to some extent by the heat of vaporization of the fuel. Additionally, by the time the suction pump fills the metering chamber with liquid fuel, the vapor fuel in the metering chamber is drawn into the engine from the fuel nozzle through the intake passage, causing the concentration of the mixture to temporarily become too high. This may make it difficult to start the engine.

[Problems to be Solved by the Invention] In view of the above-mentioned problems, an object of the present invention is to eliminate the vaporized fuel in the metering chamber of the carburetor to the outside with a simple operation when the engine is at high temperature, and to supply liquid fuel. The object of the present invention is to provide a tickler device for a diaphragm type carburetor that can easily start an engine.

[Means for Solving the Problem] In order to achieve the above object, the configuration of the present invention includes providing a drain conduit that opens the metering chamber to the atmosphere, and
A pressurized air supply means is provided for supplying pressurized air to an atmospheric chamber separated from the metering chamber by a diaphragm, whereby the inflow valve is forcibly opened, and the internal pressure of the fuel tank at high temperature of the engine is used to control the metering of the carburetor. It supplies fuel to the ring chamber.

[Function] The higher the temperature of the engine, the higher the pressure of the vapor fuel in the fuel tank 1. Atmospheric chamber 62 divided by the diaphragm 11 from the metering chamber 16 of the diaphragm type vaporizer
When pressurized air is supplied by the manually operated air pump 40, the inflow valve 10 is forcibly opened, and the fuel in the fuel tank 1 flows from the fuel pipe 9 through the inflow lower and the check valve 48 due to internal pressure (steam pressure). The fuel then enters the fuel chamber 61 and further flows into the metering chamber 16 via the check valve 47 and the passage 60. Therefore, if the temperature of the fuel tank 1 is high, the internal pressure will be high, and the liquid fuel in the fuel tank 1 will be automatically replenished into the metering chamber 16 without operating the engine coil. .

In response to the pressure of the pressurized air sent to the atmospheric chamber 62, the on-off valve 63 that releases the metering chamber 16 to the atmosphere is opened, so that the steam fuel in the metering chamber 16 flows into the drain conduit 5.
1 and then emitted into the atmosphere.

[Embodiments of the Invention] The present invention will be described based on an embodiment of an internal combustion engine attached to a chainsaw as a working machine.

As shown in FIG. 2, the chainsaw has an engine mounted inside a body 70 so that a crankshaft 78a (not actually visible from the outside) faces sideways, and is coupled to the crankshaft 78a via a one-way clutch. It is started by pulling up the rope wound around the pulley using the handle 79 (recoil operation). A blower is attached to the crankshaft 78a, and sucks cooling air through a free-flowing slit 78 provided in the side wall, cools the cylinder portion, and blows it out from the opposite side of the body 70. A fuel tank is provided at the bottom of the fuselage 70, and is filled with fuel by removing the cap 77. Aircraft 7
A handle 76 including an acceleration lever 69 is attached to the base end of the 00, and an inverted U-shaped handle 73 is attached to the center. The sawtooth 71 is integrated with an endless chain driven by a chain wheel connected to the crankshaft 78a.
is guided by the chain par 80 and projected forward from the fuselage 70. A brake lever 72 is provided adjacent to the handle 73 to stop driving the sawtooth 71 in an emergency.

A cover 74 is attached to the upper surface of the fuselage 70, and a filter as an aquarina 68 (FIG. 1) is provided inside the cover 74. A diamond slam type carburetor is provided inside the cover 74 to ensure that the engine is always supplied with the appropriate amount of fuel no matter what position the aircraft is tilted to.

As shown in FIG.
The exhaust muffler (not shown) is connected to the intake port 66 via the exhaust muffler (not shown) on the other side. A fuel tank 1 is attached to the lower end of the engine 27, that is, to the rear side of the crank chamber. A filter 8 is housed inside the fuel tank 1 , and a fuel pipe 9 connected to the filter 8 is connected to an inflow lower of the carburetor 2 .

In the carburetor 2, a cover 4 is coupled to the upper wall of a main body 3 including a venturi 17, with a diaphragm 6 interposed therebetween, and a cover 15 is coupled to the lower wall thereof, sandwiching a diaphragm 11 therebetween. The cover 4 is equipped with a pulsating pressure introduction chamber 49, and the conduit 5 connects the 2
Connected to the crank chamber of the cycle engine. The fuel v61 divided by the diaphragm 6 is connected to the inflow lower via the check valve 48, and is also connected to the metering chamber 16 via the check valve 47, the passage 6C1, and the inflow valve 10.

An atmospheric chamber 62 is formed between the diaphragm 11 and the cover 15 that partition the metering chamber 16. Needle valve type inflow valve 1
0 is disposed at the end of the passage 60 and is opened and closed by the lever 13. That is, one end of the lever 13 rotatably supported on the wall of the metering chamber 16 by the shaft 12 connects to the inflow valve 1.
It is biased and engaged with the end of 0 by the force of a spring. Lever 13
The other end abuts against a protrusion connected to the approximate center of the diaphragm 11. The metering chamber 16 is connected to the high speed fuel injection port 24 via a check valve 26 and a high speed fuel metering needle valve 25. Further, the metering chamber 16 is connected to the low-speed fuel injection port 21 via a check valve 23 and a low-speed fuel metering needle valve 22 .

The tickler device A according to the present invention includes a drain conduit 51 that opens the metering chamber 16 to the atmosphere, an on-off valve 63 that opens and closes the drain conduit 51, and a pressurized air supply means B that supplies pressurized air to the atmospheric chamber 62. It is equipped with A metal conduit is fixed to the side wall of the metering chamber 16 in the drain conduit 51, and an on-off valve 63 made of a plate having a through hole is slidably guided and supported in the middle of the conduit. The pressurized air supply means B is constituted by an air pump 40 consisting of a dropper 36. That is, the dropper 36 is supported by the wall of the body 74, and the on-off valve 37 is slidably supported on the wall, and the spring 35 is interposed between the 7 langes provided on the on-off valve 37 and the dropper 36. be done. The inside of the dropper 36 is connected to the atmospheric chamber 62 via the conduit 34. conduit 3
A T-shaped connecting pipe is connected in the middle of 4, and the above-mentioned on-off valve 63 is connected to this via a bellows 33.

Next, the operation of the tickler device of the diaphragm type vaporizer according to the present invention will be explained. If the engine 27 is stopped after high-load operation and left for some time (about 10 minutes), the heat of the engine will be dissipated into the interior of the fuselage 70, and the chamber housing the carburetor 2 will also become hot. Therefore, the fuel in the metering chamber 16 is heated and vaporized to form a vapor fuel at the fuel nozzle 2.
1 and 24 to an intake passage provided with a venturi 17. In such a state, the metering chamber 16 runs out of liquid fuel, and the recoil operation rotates the crankshaft 78a of the engine 27 and fills the crank chamber 32.
Even if the pulsating pressure is applied to the diaphragm 6 of the pulsating pressure introduction air 49 through the conduit 5, vapor fuel also exists inside the fuel tank 1, and it is impossible to instantly fill the metering chamber 16 with liquid fuel. It is.

According to the present invention, first, when the dropper 36 of the air pump 40 is crushed against the force of the spring 35, the inside of the dropper 36 is sealed by the seven lunges of the on-off valve 37, and this air is pressurized to form the conduit 34. from there to the atmospheric chamber 62. Therefore, the lever 13 is rotated via the diaphragm 11,
Inflow valve 10 opens.

At the same time, pressurized air enters the inside of the bellows 33 from the conduit 34, the bellows 33 is expanded, the on-off valve 63 moves upward, and the drain conduit 51 connects the metering chamber 16 to the atmosphere. Therefore, the vapor fuel in the metering chamber 16 is released into the atmosphere.

On the other hand, inside the fuel tank 1, liquid fuel flows from the filter 8 to the fuel pipe 9, to the inlet lower, and to the check valve 4 due to the pressure of the vapor fuel.
8, fuel chamber 61, check valve 47, passage 60 and inflow valve 1
The metering chamber 16 is fed under pressure through the However, initially, the liquid fuel in the fuel tank 1 is heated and vaporized before entering the metering chamber 16 through the passage of the vaporizer 2, becoming vaporized fuel, and is discharged from the metering chamber 16 to the atmosphere through the drain conduit 11. When the fuel passage of the vaporizer 2 is cooled by the heat of vaporization of the fuel in the fuel tank 1, the metering chamber 16 is eventually filled with liquid fuel.

At this point, when the dropper 36 is released, the conduit 34 is released to the atmosphere, and the drain conduit 51 is closed by the on-off valve 63. Then, when the crankshaft is rotated by the recoil operation, the liquid fuel in the metering chamber 16 is mixed with intake air from the fuel nozzle 21, 24 due to intake negative pressure, and is supplied to the engine 27, making it possible to restart the engine. As described above, the air to the carburetor 2 is sucked into the venturi 17 of the carburetor 2 from the intake lower 5 through the air cleaner 68.

When the engine is started, the pulsating pressure in the crank chamber 32 is introduced into the pulsating pressure introducing chamber 49, and the fuel in the fuel tank 1 is sucked into the fuel chamber 61 by the reciprocating motion of the diaphragm and the action of the check valves 48 and 47. The fuel is further supplied from the fuel chamber 61 to the metering chamber 16 via the inflow valve 10.

[Effects of the Invention] As described above, the present invention allows the atmospheric chamber 62 separated from the metering chamber 16 by the diaphragm 11 to be connected to the air pump 40.
The on-off valve 63 of the metering chamber 16
Since the air is connected to the atmosphere through a drain conduit 51 equipped with The inlet valve 10 is opened via the lever, and the liquid fuel in the fuel tank 1 is replenished into the metering chamber 16 via the inlet valve 1o due to the vapor pressure of the fuel tank 1. At the same time, the pressurized air opens the on-off valve 63 of the drain conduit 51, so the metering chamber 16
of vapor fuel is released into the atmosphere.

In this way, the liquid fuel from the fuel tank 1 is supplied to the metering chamber 16 while cooling the fuel passage of the vaporizer 2, and at the same time, the vapor fuel in the metering chamber 16 is discharged to the outside, so that the fuel passage in the vaporizer 2 is cooled and the vaporized fuel in the metering chamber 16 is discharged to the outside. When 16 is filled with liquid fuel, deactivation of air pump 40 closes drain conduit 51 and opens atmospheric chamber 62 to the atmosphere.

And the engine could be restarted quickly and reliably.
Ru.

Since the drain conduit 51 is configured to open in conjunction with the operation of the air pump 4o, it is very easy to operate.

[Brief explanation of drawings]

FIG. 1 is a side sectional view of a tickler device with a diaphragm type carburetor according to the present invention, and FIG. 2 is a perspective view of a chainsaw as a working machine on which an engine equipped with the diaphragm type carburetor is mounted. A: Tickler device B: Pressurized air supply means 1: Fuel tank 2: Carburetor 1o: Inflow valve 11: Diaphragm 16: Metering chamber 20 Throttle valve 21
:Low speed fuel nozzle 24:High speed fuel nozzle 27:Engine 3
2: Crank chamber 33: Bellows 34: Conduit 37:
On-off valve 40: Air pump 51 Nidrain conduit 62
: Atmospheric chamber 63: Open/close valve

Claims (4)

[Claims] (1) A drain conduit is provided to release the metering chamber to the atmosphere, and a pressurized air supply means is provided to supply pressurized air to the atmospheric chamber separated from the metering chamber by a diaphragm, thereby forcing the inflow valve. Teichler device is a diaphragm type carburetor that is characterized by opening automatically and supplying fuel to the metering chamber of the carburetor using the internal pressure of the fuel tank when the engine is at high temperature. (2) The diaphragm according to claim (1), wherein the drain conduit connecting the metering chamber and the atmosphere is provided with an on-off valve that is closed during engine operation and opens when pressurized air is supplied to the atmosphere chamber. Type vaporizer Teichler device. (3) The Teichler device for a diaphragm type vaporizer according to claim (1), wherein the pressurized air supply means is a manually operated air pump. (4) The Teichler device of a diaphragm type vaporizer according to claim (1), wherein the drain passage opens when pressurized air is supplied by the air pump.