JP2753535B2 - Vaporizer of internal combustion engine for portable work machine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a carburetor for an internal combustion engine for a portable working machine such as a brush cutter, and more particularly, to a fuel supply system suitable for work contents with minimum cost burden. The present invention relates to a carburetor of an internal combustion engine for a portable working machine, which can be changed.

[Prior Art] A diaphragm type carburetor (FIG. 4 (a)) is generally used as a carburetor used in an internal combustion engine for a portable working machine, and is shown in FIGS. 4 (b) to (d). Various carburetors such as overflow carburetor, float carburetor (with fuel pump) and float carburetor (without fuel pump) are selected according to the equipment and work content of the working machine, and the engine body is used in an inverted state. May be done.

Since the above-mentioned various vaporizers have no common parts such as the vaporizer main body and the constant oil level part, and the manufacturer differs depending on the type of the vaporizer, as a manufacturer of the internal combustion engine, the purchase problem of the vaporizer, handling, Various problems have occurred, such as troublesome services. In particular, the vaporizer body is generally made of aluminum die-cast, and if the vaporizer is different, the cost for preparing various die-casting dies increases.

[Problems to be Solved by the Invention] In view of the above-described problems, an object of the present invention is to assemble a unit into a common carburetor main body, so that portable work can be changed to various carburetors at a minimum cost. To provide a carburetor for an internal combustion engine.

[Means for Solving the Problems] To achieve the above object, a configuration of the present invention includes a fuel pump driven by pulsating pressure of a crankcase of an engine,
In a diaphragm type carburetor in which a constant pressure mechanism is assembled to a mounting surface at a lower portion of the carburetor body, the carburetor body is mounted to the engine in an inverted state, and the mounting surface is replaced with a constant pressure mechanism including a diaphragm and an inflow valve. An overflow unit or a float unit having a fuel oil level at the upper part can be rearranged.

[Action] The constant pressure mechanism including the diaphragm and the inflow valve is removed from the mounting surface at the bottom of the carburetor body of a standard diaphragm type carburetor, and the carburetor body is mounted upside down on the engine. The overflow unit or the flow unit is mounted on the mounting surface. Can be changed from a diaphragm type vaporizer to an overflow type vaporizer or a float type vaporizer.

FIG. 1 is a side sectional view of a standard diaphragm type vaporizer according to the present invention. The diaphragm type carburetor 1 includes a carburetor body 18, a fuel pump A, and a constant pressure mechanism B.

The carburetor body 18 having the intake passage 11 extending in the lateral direction,
A cylindrical portion 2 extending in the vertical direction is formed at the center portion, and the upper end portion is closed by a lid 12. A throttle valve 8 having a throttle hole 8a is fitted to the cylindrical portion 2 so as to be rotatable and slidable in the axial direction. A shaft 14 extending upward from the throttle valve 8 is supported by the lid 12, and a follower 16 is supported by a floor lever 15 coupled to the upper end of the shaft 14. The follower 16 is moved by the force of the spring 13 surrounding the shaft portion 14 locked between the lid 12 and the throttle valve 8.
When the front lever 15 is turned, the throttle 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. The spring 5 surrounding the rod valve 3 inside the screw hole described above is
Facilitates position adjustment. A fuel nozzle 7 whose opening degree of the fuel injection hole 6 is adjusted by the rod valve 3 is fixedly supported on the bottom wall of the carburetor body 18.

The fuel pump A is provided with a diaphragm 53 on the lower surface of the carburetor body 18.
The housing 21 is connected to the pulsating pressure introducing chamber 54 on the upper side.
, And a pump chamber 55 is defined below. The pulsating pressure introduction chamber 54 has an inlet 59 connected to the crank chamber of the two-stroke engine, and reciprocates the diaphragm 53 up and down. Pump room 55
Is connected to the fuel tank 32 via the passage 51, the check valve 10, the filter 37, and the inlet pipe 31. The pump chamber 55 is provided with the check valve 4,
It is communicated with the constant pressure chamber 38 via the passage 52 and the inflow valve 9.

The constant pressure mechanism B is configured as follows. The diaphragm 34 and the cover 35 are connected to a mounting surface 60 at the bottom of the housing 21, and a constant pressure chamber 38 is provided above the diaphragm 34, and an atmosphere chamber is provided below the diaphragm 34.
36 are defined respectively. A lever 41 is supported by a support shaft 40 inside the constant pressure chamber 38. The left end of the lever 41 is abutted against the diaphragm 34 by the force of the spring 28, while the right end locks the swash valve type inflow valve 9.

During operation of the engine, fuel in the fuel tank 32 is supplied from the inlet pipe 31 to the filter 37, the check valve 10, the passage 51, the pump chamber 55, the check valve 4,
It is sent to the constant pressure chamber 38 through the passage 52 and the inflow valve 9. Constant pressure chamber 38
Is sucked from the fuel injection hole 6 to the throttle hole 8a through the passage 47, the fuel jet 46, and the fuel nozzle 7.

In the present invention, the constant pressure mechanism B of the diaphragm type carburetor shown in FIG. 1 is configured to be interchangeable with a float unit or an overflow unit. FIG. 2 shows a state in which the constant pressure mechanism B is removed from the mounting surface 60 of the carburetor body 18 and an overflow unit C is assembled. In this case, the carburetor body 18 is connected to the engine upside down. The housing 71 of the overflow unit C is connected to the mounting surface 60, and a passage 79 provided substantially at the center of the housing 71 communicates with the fuel nozzle 7. A cylindrical portion 74 that partitions the chamber 73 is provided in the housing 71, and a cylindrical partition wall 77 that partitions the overflow chamber 61 is provided inside the cylindrical portion 74. The chamber 73 communicates with the fuel tank 32 via the outlet pipe 72. The bottom of the overflow chamber 61 communicates with the passage 52 of the fuel pump A via a passage 78.

The conical flange 75a of the outer tube 75 is connected to the lid 69 that closes the housing 71. The outer tube 75 protrudes into the overflow chamber 61. The upper end of the inner tube 76 inserted into the outer tube 75 is
The lower end is connected to the bottom of the housing 71 so as to communicate with the passage 79 at the lower end. An air bleed tube 81 whose upper end is connected to the lid 69 is inserted through the inner tube 76. Air bleed tube 81
Has an axial passage 65 and a plurality of radial small holes 80.
Passage 65 is a passage covered by lid 66, a passage of jet 67, lid 69
68, which is opened to the outlet (downstream) side of the air cleaner (not shown) through the atmosphere port 70. The passage in the gap between the outer pipe 75 and the inner pipe 76 is a fuel adjusting needle valve 63 disposed in the conical chamber 62 and the lid 69.
Through the passage 64, and furthermore, the inner tube 76 and the air bleed tube
It is communicated with the above-mentioned passage 79 through a passage in a gap between the passage 81 and the passage. The chamber 73 is communicated with the atmosphere port 70 through a notch passage and a passage 68 provided at the peripheral edge of the flange 75a of the outer tube 75.

In the embodiment of FIG. 2, the housing 29, the pump chamber 55, the passage
If the fuel inlet 79 and the like are formed integrally with the bottom of the housing 71 of the overflow unit C, and they are overlapped with the diaphragm 53 and joined together, the whole becomes compact.

Next, the operation of the above-mentioned overflow type vaporizer will be described. Fuel pumped up from the fuel tank 32 by the fuel pump A and discharged into the passage 52 is supplied to the overflow chamber 61 through the passage 78, and excess fuel overflows from the upper end of the partition wall 77 into the chamber 73, and passes through the outlet pipe 72. It is returned to the fuel tank 32. The fuel in the overflow chamber 61 passes through the passage in the gap between the outer pipe 75 and the inner pipe 76, and has a conical chamber 62, a fuel adjusting needle valve 63,
The fuel flows through the gap 64 between the inner pipe 76 and the air bleed pipe 81, the passage 79, and the fuel nozzle 7, and is sucked from the fuel injection hole 6 into the throttle hole 8a. At the same time, the air is sucked into the passage 65 and the small hole 80 of the air bleed pipe 81 from the atmosphere port 70 through the passage 68 and the jet 67, and is mixed with the fuel in the gap between the inner pipe 76 and the air bleed pipe 81 (emulsification). ) And is sucked into the fuel nozzle 7.

During stoppage of the engine, the fuel and air are emulsified between the inner pipe 76 and the air bleed pipe 81, so that the fuel does not flow out to the fuel nozzle due to the siphon effect.

FIG. 3 is a carburetor body of the diaphragm type carburetor of FIG.
In this example, the constant pressure mechanism B is removed from the mounting surface 60 of the 18 and a float unit D is assembled. In this case also the vaporizer body
18 is inverted and connected to the mechanism. A housing 71 coupled to the mounting surface 60 has a cylindrical portion defining the float chamber 49.
74 is closed by a lid 69. The upper end of the outer cylinder 75, the inner cylinder 76, and the air bleed tube 81 are connected to the lid 69, and the inside of the inner cylinder 76 is communicated with the fuel nozzle 7 through the passage 79 as in the embodiment shown in FIG. It is.

One end of the lever 42 is rotatably supported by the support shaft 43 by the housing 71, and one end of the lever 42 is connected to the float 48, and the other end supports the inflow valve 44. Accordingly, when the fuel oil level 82 in the float chamber 49 decreases, the inflow valve 44 opens and the fuel pump A
The fuel discharged from the passage 52 is supplied to the float chamber 49 through the passage 45 and the inflow valve 44. When the fuel oil level 82 reaches a predetermined height, the buoyancy of the float 48 causes the lever 42 to pivot.
Rotated clockwise around 43, the inflow valve 44 closes,
Prevent excess fuel flow.

In the embodiment shown in FIG. 3, when the fuel tank 32 is disposed above the float unit D (see FIG. 1 (d)), the pipe drawn from the fuel tank is simply connected to the inlet 45. Frequently, fuel pump A is not required, thus saving costs.

[Effects of the Invention] As described above, the present invention relates to a diaphragm-type carburetor having a fuel pump driven by pulsating pressure in a crankcase of an engine and having a constant-pressure mechanism mounted on a mounting surface at a lower portion of the carburetor body. The carburetor body is mounted in an inverted state, and instead of a constant pressure mechanism including a diaphragm and an inflow valve on the mounting surface,
An overflow unit or a float unit that has a fuel oil level above the fuel nozzle can be rearranged, and an overflow type or float type fuel supply unit is mounted on the mounting surface of the carburetor body using the carburetor body as a common part. By rearranging, it is possible to provide a carburetor having various fuel supply systems with a minimum number of parts, which contributes to cost reduction.

[Brief description of the drawings]

1 is a side sectional view of a carburetor of an internal combustion engine for a portable working machine according to the present invention, FIG. 2 is a side sectional view of an overflow type carburetor, FIG. 3 is a side sectional view of a float type carburetor, FIG. FIG. 1 is a side view showing a mounting state of various carburetors in a conventional internal combustion engine. A: fuel pump, B: constant pressure mechanism, C: overflow unit,
D: float unit, 1: diaphragm type carburetor, 7: fuel nozzle, 8: throttle valve, 18: carburetor body, 44: inflow valve, 48: float, 60: mounting surface, 61: overflow chamber

Claims (1)

(57) [Claims] 1. A diaphragm type carburetor having a fuel pump driven by a pulsating pressure of a crankcase of an engine and having a constant pressure mechanism mounted on a mounting surface at a lower portion of the carburetor body. An internal combustion engine for a portable working machine, wherein an overflow unit or a flow unit having a fuel oil level above a fuel nozzle can be replaced, instead of a constant pressure mechanism including a diaphragm and an inflow valve on the mounting surface. Vaporizer.