JPH0237158A - Diaphragm type carbureter - Google Patents

Abstract

PURPOSE:To obtain a diaphragm type carbureter which an be started with simple operation and has no problem of safety by providing between a metering room and a fuel jet a solenoid switching valve communicated with a fuel-tank. CONSTITUTION:A solenoid switching valve C including an electromagnetic actuator D is moved up to isolate a metering room 38 from a fuel jet 46 so that the room is communicated with a fuel tank 32 via a passage 50. Fuels retained in the fuel tank 32 are supplied to the metering room 38 by an electromagnetic type primer pump 72 and then excess fuels are, together with vaporized fuels inside the metering room 38, forced to flow back into the fuel tank 32 via the solenoid switching valve C and the passage 50. The electromagnetic actuator D is demagnetized to move the switching valve C back in its position so as to communicate the metering room 38 with the fuel jet 46, then an engine is started so that fuels are absorbed in the air intake passage 11 of a carbureter from a nozzle hole 6 via the switching valve C and the fuel jet 46.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a diaphragm type carburetor that is easy to start and whose primer pump automatically operates when an engine is started.

[Prior Art 1] An internal combustion engine installed in a portable working machine such as a brush cutter is equipped with a diaphragm type carburetor so that fuel can be continuously supplied even if the engine is tilted.

In other words, fuel is supplied from the fuel tank to the metering chamber by a diaphragm fuel pump that utilizes the pulsating pressure in the crank chamber of *m, and the fuel in the metering chamber is sucked into the intake passage of the carburetor by negative intake pressure. Ru. An inflow valve is provided at the entrance of a metering chamber surrounded by a diaphragm, and when fuel becomes insufficient, the fuel inflow valve opens and fuel is supplied by a diaphragm fuel pump.

However, when the engine is stopped, ambient heat increases the fuel pressure in the metering chamber, and the fuel gradually runs out.If air enters the metering chamber, the handling of the air in the metering chamber becomes difficult when the engine is started. This is bad and prevents smooth starting.

Therefore, in the diaphragm type carburetor disclosed in Japanese Utility Model Publication No. 51-43315, before starting the engine, the check valve in the passage connecting the metering chamber and the intake passage is pushed open by a ticker to drain the air in the metering chamber. At the same time, the metering room is refilled with fuel from the fuel tank using a hand pump. In this case, it is necessary to use both hands, which makes the operation of the Rh-type portable working machine cumbersome. Furthermore, whether or not starting fuel has been filled into the metering chamber is checked by checking the excess fuel discharged outside, which is not desirable from a safety standpoint.

[Problems to be Solved by the Invention] In view of the above-mentioned problems, the object of the present invention is to provide a fuel metering chamber filled with fuel using an electric primer pump and excess fuel returned to the fuel tank, which is easy to start and operate. The object of the present invention is to provide a diaphragm type vaporizer that is free from safety problems.

[Means for Solving the Problem] In order to achieve the above object, the configuration of the present invention includes an electric primer pump between the fuel tank and the diaphragm fuel pump of the carburetor, and metering of the fuel supply mechanism. An electromagnetic switching valve is provided between the chamber and the fuel jet, which normally communicates the metering chamber with the fuel jet and communicates the metering chamber with the fuel tank during a starting operation.

[Operation] When the N magnetic switching valve C having the IR magnetic actuator D is pushed up against the force of the spring, the metering v38 is cut off from the fuel jet 46 and communicated with the fuel tank 32 via the passage 50. .

An electromagnetic primer pump 72 connected to an electric motor 71 meters the fuel in the fuel tank 32 through the passage 31, the check valve 10, the passage 51, the pump chamber 55, the check valve 4, the passage 52, and the fuel inlet valve 9. is supplied to chamber 38. The excess fuel together with the vaporized fuel in the metering chamber 38 flows through the passage 80.
The fuel is returned to the fuel tank 32 via the electromagnetic switching valve C1 passage 50.

When the electromagnetic actuator D is demagnetized, the switching valve C is returned and the metering chamber 38 is communicated with the fuel jet 46 . When the engine is started by the starter motor 60, the fuel in the metering chamber 38 flows through the passage 80, the switching valve C1, and the fuel jet 4.
6 and from the injection hole 6 of the fuel supply pipe 7 to the intake passage 1 of the carburetor.
1 and supplied to the engine as a mixture.

[Embodiments of the Invention] As shown in FIG. 1, a diaphragm type carburetor according to the present invention includes a main body 18, a diaphragm fuel pump A, a fuel supply 11 mB, and a switching valve C driven by an electromagnetic actuator D. , and a primer pump 72 driven by an electric motor 71.

A cylindrical portion 2 extending in the vertical direction is formed in the center of the main body 18 having an intake passage 1'1 extending in the lateral direction, and the upper end of the cylindrical portion 2 is closed by a lid 12. A rotary throttle valve 8 having a throttle hole 8a is fitted into the cylindrical portion 2 so as to be rotatable and movable in the axial direction.

A shaft portion 14 extending upward from the throttle valve 8 is supported by the lid 12, and a lever 15 connected to the upper end of the shaft portion
is supported. The shaft portion 1 is located between the lid 12 and the comparative valve 8.
Due to the force of the spring 13 surrounding the follower 16
The lever 15 is biased into engagement with the cam 17 provided on the lever 2.
When the valve 8 is rotated, the valve 8 moves in the axial direction. At this time,
The rod valve 3 integrated with the adjustment bolt 14a screwed into the screw hole of the shaft portion 14 also moves in the axial direction. A spring 5 surrounding the rod valve 3 inside the threaded hole pushes the rod valve 3 against the shaft portion 14.
facilitates adjustment of position.

A fuel supply pipe 7 whose opening degree of the nozzle hole 6 is adjusted by the rod valve 3 is fixedly supported on the bottom wall of the main body 18 . The fuel supply pipe 7 is communicated via a fuel jet 46 and a switching valve C to a metering chamber 38 that holds fuel at a constant pressure.

The fuel pump A has a main body 70 connected to the lower surface of the main body 18 by sandwiching a die N7 flamm 53, and has a pulsating pressure intake chamber 54 on the upper side.
A pump chamber 55 is formed on the lower side. The pulsating pressure introduction chamber 54 has an inlet 59 connected to, for example, a crankshaft of a two-stroke engine, thereby causing the diaphragm 53 to reciprocate up and down. The pump seedling 55 includes a passage 51, a check valve 10, and a filter 37.
, passage 31, and a fuel tank 32 via a primer pump 72 driven by an electric motor n71.

Further, the pump chamber 55 can communicate with the metering chamber 38 via the check valve 4, the passage 52, and the fuel inflow valve 9.

A diaphragm 34 and a cover 28 are coupled to the lower surface of the main body 70, thereby defining a metering chamber 38 on the upper side and an atmospheric chamber 36 having an atmospheric air port 58 on the lower side.

A lever 41 is installed inside the metering v38 by a support shaft 40.
is supported. The left end of the lever 41 has a rivet 34a (second
(Fig.), while the right end supports a poppet-type fuel inlet valve 9.

The electromagnetic actuator D includes an electromagnetic coil 73 fixed to the cover 28 and a plunger 73a that projects upward when the electromagnetic coil 73 is excited. Plunger 7
When 3a protrudes upward, it collides with the rivet 34a of the diaphragm 34, and further pushes up the switching valve C via the lever 41 against the force of the spring 77 (FIG. 2).

As shown in FIG. 2, the switching valve C consists of a valve chamber 74 provided in the main body 70 and a valve body 75a. The side of the valve chamber 74 communicates with the metering v38 via a passage 80. Further, the upper end of the valve chamber 74 communicates with the fuel generator I-46, and the lower end thereof communicates with the fuel tank 32 through a passage 50. stem 75
is fitted into the shaft hole of the main body 70 via the seal member 76,
and a retaining ring 78 locked to the end of the stem 75 and the main body 70
The passage 50 is normally closed by a spring 77 interposed between the wall and the
is biased to close the ends of the

FIG. 3 shows the electric power that drives the primer pump 72. l1 machine 71
, is a drive circuit diagram of the electromagnetic coil 731 of the electromagnetic actuator D and the dynamic motor 60. 66 is a power source battery, 67.
68 is a switch that drives the electric motor 71 and the electromagnetic coil 73 in conjunction with each other, and 69 is a switch that drives the starting motor 60.

Next, the operation of the diaphragm type carburetor according to the present invention will be explained. When the switches 67 and 68 are pressed before starting the engine, the plunger 73a of the electromagnetic actuator D is pushed up, the fuel inflow valve 9 is pulled down and opened by the lever 41, and the valve body 75a of the switching valve C is pushed up. The passage 80 and the passage 50 communicate with each other. In addition, the electric motor 71
Since the primer pump 72 is driven, the fuel in the fuel tank 32 is supplied to the primer pump 72, the passage 31, the filter 37, the check valve 10, the passage 51, the pump chamber 55, the check valve 4, the passage 52, and the fuel inlet valve 9. Metering room 38 via
supplied to The air in the metering 38 and the excess fuel pass through the passage 80, the valve chamber 74, and the passage 50 to the fuel tank 32.
is discharged to.

When the metering chamber 38 is filled with fuel in this way, the switches 67 and 68 are opened and the switch 69 is closed, and the starter motor 60 is rotated. Due to negative pressure in the intake passage 11 as the engine cranks, fuel in the metering chamber 38 is sucked into the intake passage 11 from the nozzle hole 6 of the fuel supply pipe 7 via the passage 80, the valve chamber 74, and the fuel jet 46. It is mixed with intake air and supplied to the engine, thereby allowing the engine to start smoothly.

When the fuel in the metering chamber 38 becomes low, the fuel inlet valve 9 opens, and the diaphragm 53 of the fuel pump A, which is moved up and down by the pulsating pressure in the crank chamber, allows the fuel in the fuel tank 32 to flow through the gap between the primer pump 72, the passage 31, The fuel is sucked into the pump chamber 55 via the filter 37, the check valve 10, and the passage 51, and further supplied to the metering chamber 38 via the check valve 4, the passage 52, and the fuel inlet valve 9.

In the embodiment shown in FIG. 4, in order to separately supply starting fuel and generate a rich mixture when the engine is cold-started, a fuel pressurizing mechanism E that holds the fuel under pressure and a pressurized It includes a fuel release valve F that supplies fuel to the intake passage 11 during startup, and a relief valve 26 that returns excess fuel to the fuel tank 32.

The fuel pressurizing mechanism E has a diaphragm 61 sandwiched between the cover 28 and the presser plate 56 to form an atmospheric chamber 64 having a pressure accumulating chamber 62 on the upper side and an atmosphere port 58a on the lower side. A spring 63 is interposed between the two. Passage 50 communicates with pressure accumulation chamber 62 via check valve 57 . The pressure accumulation chamber 62 can communicate with the fuel tank 32 via the passage 30, the valve chamber 25, the relief valve 26, and the passage 29.

The fuel release valve F is an electromagnetic coil 4 fixed to the wall of the main body 18.
8, and the valve body 4 integrated with the plunger 47a fitted therein.
7, and the valve body 47 is biased toward the valve seat 49 by the spring 24. The valve seat 49 connects the valve chamber 25 and the throttle valve 8 of the cylindrical portion 2.
It is arranged at the end of the passage 20 that connects the lower chamber 19. The other configurations are similar to the embodiment shown in FIG.

As shown in FIG. 5, a switch 44 interlocked with a switch 69 is connected to the energizing circuit of the electromagnetic coil 48 of the fuel release valve F.
A temperature switch 42 disposed on the wall of the engine that closes the circuit when the temperature is below a predetermined temperature is connected in series.

In this embodiment, when the switches 67 and 68 are closed, the switching valve C is switched, and the fuel in the fuel tank 32 is supplied to the metering chamber 38 by the primer pump 72, and the excess fuel is passed through the passage 80 and the switching valve C1 passage 50. , enters the pressure accumulation chamber 62 via the check valve 57, and returns to the fuel tank 32 via the passage 30, the valve chamber 25, the relief valve 26, and the passage 29.

Then switch 67.68 is opened and switch 44.6 is opened.
When closing 9, Tl! When the ambient temperature of ApA is below a predetermined value, the valve body 47 of the fuel release valve F is pushed down against the force of the spring 24, so that the fuel in the pressure accumulation chamber 62 pressurized by the force of the spring 63 is released from the passage. 30, the valve chamber 25, and the passage 20 into the space 19 below the throttle valve 8. At the same time, as the engine cranks, the fuel supplied from the metering chamber 38 to the nozzle hole 6 due to intake negative pressure and the fuel in the chamber 19 are turned into a rich mixture in the intake passage 11 and supplied to the engine smoothly. The engine is installed 9i3.

[Effects of the Invention] As described above, the present invention includes an electric primer pump between the fuel tank and the diaphragm fuel pump of the carburetor, and an electric primer pump between the metering chamber of the fuel supply mechanism and the fuel jet. Equipped with an electromagnetic switching valve that connects the metering chamber to the fuel jet and connects the metering chamber to the fuel tank during engine startup. and the electric primer pump are activated, and the primer pump replenishes the fuel in the fuel tank into the metering chamber, and at the same time, the air and excess fuel in the metering chamber are smoothly discharged into the fuel tank. The preparation system for supplying fuel to the intake passage of the carburetor is completed. Next, the primer pump is stopped, the switching valve is returned to its original position, and the starter electric motor 171m is activated.The fuel in the metering chamber is sucked into the intake passage of the carburetor, and the air-fuel mixture is supplied to the engine, allowing the engine to run smoothly. Starting the Engine According to the present invention, the engine can be easily started by simply operating a switch, especially when the user is wearing a backpack-type portable working machine on his or her back, making it easy to operate the working machine.

[Brief explanation of the drawing]

Fig. 1 is a side sectional view of a diaphragm type vaporizer according to the present invention, Fig. 2 is an enlarged view of the main part of Fig. 1, Fig. 3 is an electric circuit diagram, and Fig. 4 is a second embodiment of the present invention. FIG. 5 is a side cross-sectional view of such a diaphragm type vaporizer, and is an electrical circuit diagram thereof.

Claims (3)

[Claims] (1) An electric primer pump is provided between the fuel tank and the diaphragm fuel pump of the carburetor, and the metering chamber and the fuel jet are normally connected between the metering chamber and the fuel jet of the fuel supply mechanism. , a diaphragm type carburetor characterized by being equipped with an electromagnetic switching valve that communicates the metering chamber with the fuel tank during starting operation. (2) The diaphragm type vaporizer according to claim (1), wherein the electric primer pump and the electromagnetic switching valve operate simultaneously. (3) The diaphragm type carburetor according to claim (1), which stores starting fuel in a pressure accumulator before starting the engine and supplies the starting fuel to the engine when the starting motor is activated.