JP2003065160A - Vertical throttle valve type carburetor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vertical throttle valve type carburetor capable of casting a carburetor body and a fuel storage tank in one body, simply assembling and disassembling a choke valve, and having one vent passage not blocked with fuel even if the carburetor is declined before and behind or right and left. SOLUTION: A fuel chamber 22 is formed by closing the fuel storage tank 2a combined with the carburetor body 22 with a bottom plate 4, and a fixed oil level is formed with a float 21. A high speed fuel nozzle hole 13 and a low speed fuel nozzle hole 23 vertical to a throttle valve shaft 6 and projecting to the center of an inlet passage 12 are installed in the carburetor body 2. A shaft part 7b of the lower part of a choke valve 17 is inserted into a shaft hole of the bottom of the inlet passage through a spring. The valve shaft 7 supported with the carburetor body 2 is fit to a boss of the upper part of the choke valve 17. A pair of vent passages (grooves) whose one end is opened to an inlet end and the other end is opened to the fuel chamber 22 is installed in the upper wall part of the carburetor body 2, and covered with a cover plate 10. A flange part 7c of the valve shaft 7 is energized downward with the cover plate 10.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD OF THE INVENTION
The present invention relates to an improvement of a vertical throttle valve type carburetor of a type in which a high-speed fuel injection hole (main fuel nozzle) is laterally projected to a bench lily portion of an intake passage, which is filed under No. 209,404.

[0002]

2. Description of the Related Art A general-purpose internal combustion engine has a centrifugal rotation control mechanism, that is, a governor mechanism, as shown in FIG.
The opening degree of the throttle valve 16 of the carburetor is adjusted with respect to the load change during operation to always keep the engine rotation speed constant, work efficiency is improved, and engine overrotation is prevented. Therefore, a return spring for rotating the throttle valve 16 to the closed position is not used for the valve shaft 6 of the throttle valve 16 of the carburetor, and the governor mechanism and the valve shaft 6 of the throttle valve 16 are connected by a rod. In order to simplify the connection between the governor mechanism of the engine and the valve shaft 6 of the throttle valve 16, the intake yoke 12 of the carburetor main body 2 is connected to the intake yoke 12 on the inlet side, and the outlet side is connected to the throttle valve 16 in the vertical direction. It is supported by the valve shafts 7, 6. A high-speed fuel injection hole (main fuel nozzle) from a passage member 26 of a fuel storage tank 28 for accommodating the float 21, which is connected to a bottom portion of the carburetor main body 2 to a bench lily portion between the intake yoke 12 and a throttle valve 16. 13 is projected, and a low speed fuel injection hole (not shown) is projected from the passage 25 of the passage member 26 to the vicinity of the closed position of the throttle valve 16. The lower end of the passage member 26 is supported by the fuel storage tank 28 by the screw plug 27.

However, in the above vertical throttle valve type carburetor,
During low speed operation in which the yoke valve 17 is open and the throttle valve 16 is near the closed position, the air flowing through the intake passage 12 is
2 flows to both sides of the high speed fuel injection hole 13 to the engine, and not only the intake negative pressure acting on the high speed fuel injection hole 13 is weak, but also the high speed fuel injection hole 13 due to the fluctuation of the intake negative pressure due to the turbulence of the air flow.
The amount of fuel sucked out of the engine fluctuates (varies), and the low-speed operation of the engine becomes unstable. Since the carburetor main body 2 and the fuel storage tank 28 are separated, it takes time to disassemble and clean the fuel storage tank 28. Moreover, it is troublesome to process the vent passage.

[0004]

SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide a vertical throttle valve type carburetor capable of integrally casting a carburetor body and a fuel storage tank.

Another object of the present invention is to provide a vertical throttle valve type carburetor which has a simple structure of the chiyoke valve and which can be easily assembled and disassembled in the carburetor.

Another object of the present invention is to arrange a pair of vent passages so as to cross each other, so that even if the carburetor tilts forward or backward or left and right, there is one vent passage which is not closed by fuel. To provide a type throttle valve type carburetor.

Another object of the present invention is to provide a vertical throttle valve type carburetor capable of obtaining a large buoyancy with a small float.

Another object of the present invention is to provide a vertical throttle valve type carburetor in which the low speed fuel adjusting member cannot be adjusted when the carburetor is attached to the engine in order to comply with exhaust gas regulations. .

[0009]

In order to solve the above-mentioned problems, the structure of the present invention is provided with a high-speed fuel injection hole and a low-speed fuel injection hole in the intake passage that traverses the carburetor main body, and is provided at the bottom of the carburetor main body. A constant oil level is formed in the fuel chamber by a float, a vertical throttle valve shaft is arranged in the intake passage, and the high-speed fuel injection hole is projected perpendicularly to the throttle valve shaft and at the height of the center of the intake passage. In the vertical throttle valve type carburetor, the carburetor body and the fuel storage tank are integrally formed, and the lower end of the fuel storage tank is closed by a bottom plate to form the fuel chamber.

Further, according to the structure of the present invention, the chiyoke valve and the upper valve shaft are separately molded from synthetic resin, the boss portion is provided on the upper portion of the chiyoke valve, and the hollow shaft portion is provided on the lower portion. A spring for urging the chain yoke valve upward is housed, the shaft portion is inserted into a conical shaft hole provided at the bottom of the intake passage, and the upper valve shaft that penetrates the carburetor main body from the upper portion of the intake passage is installed. ,
It is characterized in that the flange portion of the upper valve shaft is urged downward by a lid plate which is fitted and integrated with the boss portion of the chain valve and is superposed and coupled to the upper wall surface of the carburetor body.

Further, according to the structure of the present invention, the upper wall portion of the carburetor body has a groove which communicates with the inlet opening at one end to the inlet end of the intake passage and the outlet opening at the other end to the ceiling wall of the fuel chamber. A pair of vent passages are provided so that the vent passages are covered by the cover plate, and the pair of vent passages communicates the right inlet with the left outlet of the fuel chamber and the left inlet with It is characterized in that it communicates with the outlet of the right side portion of the fuel chamber, and a pair of vent passages intersect at the upper wall portion of the carburetor main body.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a cylindrical fuel storage tank is integrally formed at the bottom of a carburetor main body by casting, and a bottom plate is connected to the lower end of the fuel storage tank by a plurality of bolts to simplify the construction and processing of the main body. Turn into.

The valve shaft of the chiyoke valve has a modified cross-section, which is below the flange, supported through the shaft hole of the main body, and is fitted to the boss at the upper end of the chiyoke valve. The flange portion is lightly sandwiched by the upper end surface of the main body by a cover plate having a notch slightly wider than the outer diameter of the valve shaft. The shaft portion at the lower end of the chiyoke valve is supported by a shaft hole in the bottom wall of the intake passage via a spring.

On the upper wall of the carburetor body, a pair of vent passages each having a groove communicating with an inlet opening at one end to the inlet end of the intake passage and an outlet opening at the other end to the ceiling wall of the fuel chamber. And the vent passage is covered with the lid plate.

The hollow pyramidal float axially supports the arm formed at the small end in the fuel chamber and welds the lid to the large end. The welding area is minimized, the temperature rise inside the float due to welding is suppressed, and hot air vent holes during welding are eliminated.

A fuel adjusting member is provided near the low-velocity fuel injection hole so that it can be adjusted at the time of manufacturing the carburetor, but it cannot be adjusted after it is assembled to the engine because it is blocked by the bolt for attaching the carburetor body to the engine. .

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, a vertical throttle valve type carburetor for a general-purpose engine according to the present invention is provided with a lever 7a on the inlet side of an intake passage 12 which crosses a carburetor body 2 made of aluminum or the like.
With the valve shaft 7 and the shaft portion 7b in the vertical direction having a through hole 17
A chain yoke valve 17 having a is supported, and a throttle valve 16 is supported on the outlet side of the intake passage 12 by a vertical valve shaft 6 having a lever 6a. The shaft portion of the valve shaft 7 having a modified cross section below the flange portion 7c penetrates the shaft hole of the main body 2 and is fitted into the boss portion of the upper end of the chioke valve 17. Flange part 7c
Is lightly clamped to the upper end surface of the main body 2 by a cover plate 10 having a notch (FIG. 5) slightly wider than the outer diameter of the valve shaft 7. The hollow shaft portion 7b is formed integrally with the lower end of the chain yoke valve 17, and is supported by a conical shaft hole provided in the bottom wall of the intake passage 12 via a spring for biasing the chain yoke valve 17 upward. It With the above configuration, the assembling of the yoke valve 17 becomes easy. Instead of the spring, as shown in FIG. 8, a pair of pawls 7 abutting against the bottom surface of the intake passage 12 are provided at the lower end of the chioke valve 17.
9 may be provided.

As shown in FIG. 5, the protruding piece 6b integral with the lever 6a abuts on an adjusting bolt 8 screwed into a rib 10a protruding upward from the cover plate 10 to regulate the idle position of the throttle valve 16. It A groove as a vent passage described later is provided on the upper end wall of the main body 2, the gasket and the cover plate 10 are superposed on the upper end wall of the main body 2, and the bolt 9 is attached to the screw hole 9 of the main body 2.
a (FIG. 6) is screwed and fixed.

A cylindrical fuel storage tank 2a is integrally formed by casting at the bottom of the carburetor main body 2. As shown in FIGS. 4 and 6, the bottom plate 4 having the recess 5 with the seal member sandwiched therebetween is abutted on the lower end of the fuel storage tank 2a, and the plurality of bolts 55 are screwed into the screw holes 55a of the projecting pieces of the fuel storage tank 2a. And then fixed. The float 21 is accommodated in the fuel chamber 22 of the fuel storage tank 2a. The float 21 made of a synthetic resin has a pair of right and left engaging arms and a single receiving arm 19 vertically spaced between a pair of left and right triangular plate pieces protruding from a small end of a hollow pyramid. Be formed. A lid is welded to the large end of the hollow pyramid.

The float 21 has a receiving arm 19 supported by a support shaft 18 so as to be tiltable between a pair of left and right leg pieces integrated with a valve housing 14 connected to the bottom of the carburetor body 2. Inflow valve 15 whose lower end is locked between the engaging arm and the receiving arm 19
Is inserted into the valve housing 14 so as to be able to move up and down. The passage 54 a extending upward from the valve housing 14 is communicated with the fuel inlet pipe 54 protruding laterally of the main body 2, and the fuel inlet pipe 5
4 is connected to a fuel tank (not shown).

As shown in FIGS. 3 and 4, according to the present invention, the main fuel nozzle, that is, the high-speed fuel injection hole 13 is supported on one side wall of the intake passage 12 adjacent to the bench lily portion. A lateral through hole into which the high-speed fuel injection hole 13 is fitted is provided in the carburetor main body 2, and the outer end of the through hole is closed by a disc-shaped plug 60. The side wall of the carburetor main body 2 is provided with a vertical passage hole intersecting the above-mentioned through hole, and the small-diameter upper end portion of the passage hole is provided.
The upper end of the emulsion tube 63 having a large number of through holes is press-fitted. The upper end of the passage hole is connected to a vent passage 42 formed of a groove via an air jet 59. The vent passage 42 has an inlet 4 that opens to the inlet end of the carburetor body 2 as described later.
It is connected to 1. The passage hole and the emulsion tube 63 described above.
Is communicated with and inserted into the passage hole 64 of the passage member 62 which is joined to the bottom portion of the carburetor main body 2 with the seal member 80 interposed therebetween.
A high-speed fuel jet 56 made of metal is fitted to the lower end of the passage member 62 made of synthetic resin with an O-ring sandwiched between it and the lower end flange, and is partially supported by the bottom plate 4.
The high speed fuel jet 56 communicates with the recess 5 in the fuel chamber 22. An annular groove is formed on the outer peripheral surface of the high speed fuel jet 56 and is engaged with an annular protrusion formed in the circular hole of the passage member 62.

As shown in FIG. 2, the passage member 62 is provided with a passage hole 64 through which the emulsion tube 63 is inserted and a passage hole 65 which is communicated at the bottom. The passage hole 65 is connected to the vent passage 42 formed of a groove through the low speed fuel jet 66 and the air jet 69 of the main body 2. The passage between the low speed fuel jet 66 and the air jet 69 extends to the outlet end of the body 2 and is connected to a passage 70 closed by a ball plug 73. As shown in FIG. 7, a low-speed fuel chamber having a plurality of low-speed fuel injection holes 23 is provided in the middle of the passage 70, and the low-speed fuel adjusting member 71 having a notch groove in a conical portion integral with the plug 74 is provided in the low-speed fuel chamber. Are fitted. Three low-speed fuel injection holes 23
Is opened to the vicinity of the closed position of the throttle valve 16 of the intake passage 12 and a portion upstream of the vicinity of the closed position. From between the low speed fuel adjusting member 71 of the passage 70 and the ball plug 73, the low speed fuel injection hole 7
2 is opened to a portion of the intake passage 12 downstream of the closed position of the throttle valve 16. Although the degree of communication between the cutout groove and the passage 70 is adjusted by the rotation of the low-speed fuel adjusting member 71, it penetrates through the through holes 53, 53a of the both-end flanges 51, 51a of the main body 1.
When the carburetor main body 2 is attached to the engine by the pair of mounting bolts 77, the low speed fuel adjusting member 71 is blocked by the mounting bolts 77 and cannot be operated.

As shown in FIGS. 4 and 6, the upper end wall of the main body 2 has a pair of left and right vent passages 32 to 35 and 42 to 42 formed of grooves.
44 is provided. At the inlet end of the main body 2, inlets 31 and 41 made of a pair of left and right axial holes (parallel to the intake passage 12)
Is opened. The inlet 31 is an inverted U-shaped passage consisting of an axial passage 32, a lateral passage 33, and an axial passage 34,
It opens into the fuel chamber 22 through a lateral passage 35, an up-down outlet 36 near the inlet end of the body 2 on the side opposite the inlet 31. The inlet 41 has an axial passage 42, a lateral passage 43,
An inverted L-shaped passage 44, an up-down outlet 46 near the outlet end of the main body 2 on the side opposite to the inlet 41, and the fuel chamber 2
Open to 2.

An air purifier is connected to the flange 51 of the carburetor main body 2, and the flange 51a is abutted against the intake port of the engine through a heat insulating pipe to form a pair of left and right through holes 53, 53a.
It is fixed to the wall of the engine by a pair of mounting bolts 77 penetrating through. Fuel from the fuel tank is supplied to the fuel chamber 22 through the fuel inlet pipe 54, the passage 54a, and the inflow valve 15 which is closed and opened according to the vertical displacement of the float 21.

During low and medium speed operation of the engine, the chiyoke valve 17 is fully opened as shown in FIG. 1, and the throttle valve 16 is opened a little larger than the closed position. When the air flowing through the intake passage 12 passes through the bench lily portion, the fuel is sucked from the high speed fuel injection hole 13, and when the air passes through the throttle valve 16, the low speed fuel injection hole 2
The fuel is sucked from 3,72, forms a mixture, and flows into the engine.

In the present invention, the high-speed fuel injection holes 13 and the low-speed fuel injection holes 23, 72 are arranged on the side wall of the intake passage 12 in a direction perpendicular to the central axis of the intake passage 12, and particularly at low and medium speeds of the engine. Since air flows along the side wall of the intake passage 12 during operation, the intake negative pressure acting on the high-speed fuel injection hole 13 is always stable, and the fuel amount according to the opening of the throttle valve 16 is stable. It is sucked into the intake passage 12 from the high-speed fuel injection hole 13. Therefore, there is no fluctuation or variation in the fuel amount at low and medium speed operation of the engine, and stable and smooth operation of the engine can be obtained.

[0027]

As described above, according to the present invention, since the high-speed fuel injection hole is arranged near the opening direction of the throttle valve even in the partial load operation of the engine, the negative pressure acting on the high-speed fuel injection hole is weak. Not only that, the switching between the low-speed system fuel passage and the high-speed system fuel passage is smooth, the setting of the carburetor is facilitated, and the transient response of rapid acceleration and rapid deceleration of the engine is improved.

By forming a cylindrical fuel storage tank integrally with the bottom of the carburetor main body by casting and connecting the bottom plate to the lower end of the fuel storage tank, the construction and processing of the carburetor main body are simplified.

The valve shaft flange portion penetratingly supported in the shaft hole of the carburetor main body is lightly sandwiched by the cover plate on the upper end surface of the carburetor main body,
While fitting the valve shaft to the boss portion at the upper end of the chain yoke valve,
By supporting the shaft portion at the lower end of the chiyoke valve in the shaft hole of the bottom wall of the intake passage via a spring, the assembly and removal of the chiyoke valve becomes easy.

The pair of vent passages can be easily routed with respect to the carburetor body, and the inclination characteristic of the carburetor is improved.

Since the float is arranged in the center of the fuel chamber just below the bench lily part, a simple pyramid-shaped float can be adopted, which is small and lightweight and has a large buoyancy, and the fuel chamber (float chamber)
Since the capacity of the float can be reduced, the float is less susceptible to the vibration of the engine, and the earthquake resistance and durability are improved.

Since the float is formed by welding the lid to a portion having a small welding area away from the shaft supporting portion, it is not necessary to provide a hot air vent hole for preventing expansion of internal air at the time of welding.

[Brief description of drawings]

FIG. 1 is a left side sectional view of a vertical throttle valve type carburetor for a general-purpose engine according to the present invention.

FIG. 2 is a right side sectional view of the vertical throttle valve type carburetor.

FIG. 3 is a front view of the vertical throttle valve type carburetor.

FIG. 4 is a front sectional view of the vertical throttle valve type carburetor.

FIG. 5 is a plan view of the vertical throttle valve type carburetor.

FIG. 6 is a plan sectional view of the vertical throttle valve type carburetor.

FIG. 7 is a plan sectional view of the vertical throttle valve type carburetor.

FIG. 8 is a side view of a chain yoke valve of the vertical throttle valve type carburetor.

FIG. 9 is a left side sectional view of a conventional vertical throttle valve type carburetor.

[Explanation of symbols]

2: Vaporizer main body 2a: Fuel storage tank 4: Bottom plate 6: Valve shaft 6a: Lever 7: Valve shaft 7a: Lever 7b: Valve shaft 7c: Flange portion 8: Adjustment bolt 10: Lid plate 1
0a: rib 12: intake passage 13: high-speed fuel injection hole 1
5: Inflow valve 16: Throttle valve 17: Chiyoke valve 18:
Spindle 19: Receiving arm 21: Float 22: Fuel chamber
23: Low-speed fuel injection hole 31: Inlet 32-35: Vent passage 36: Outlet 41: Inlet 42-44: Vent passage 46: Outlet 51: Flange 51a: Flange
53: through hole 53a: through hole 54: fuel inlet pipe 54
a: passage 56: high-speed fuel jet 59: air jet 60: plug 62: passage member 63: emulsion tube 6
4: Passage hole 65: Passage hole 66: Low speed fuel jet 6
9: Air jet 70: Passage 71: Low speed fuel adjusting member 72: Low speed fuel injection hole 73: Ball plug 77: Bolt 79: Claw 80: Seal member

Claims (11)

[Claims] 1. A vertical throttle is provided with a high-speed fuel injection hole and a low-speed fuel injection hole in an intake passage that traverses the carburetor main body, and a constant oil surface is formed by a float in a fuel chamber provided in the lower portion of the carburetor main body. In a vertical throttle valve type carburetor in which a valve shaft is arranged in the intake passage and the high-speed fuel injection hole is projected perpendicularly to the throttle valve shaft and at the height of the center of the intake passage, the carburetor body and the fuel storage tank are Formed integrally,
A vertical throttle valve type carburetor, characterized in that the lower end of the fuel storage tank is closed by a bottom plate to form the fuel chamber. 2. A tee yoke valve and an upper valve shaft are molded separately from a synthetic resin, a boss portion is provided on an upper portion of the tee yoke valve, and a hollow shaft portion is provided on a lower portion of the tee yoke valve. A spring for biasing the valve into a conical shaft hole provided at the bottom of the intake passage, and the upper valve shaft penetrating the carburetor main body from the upper portion of the intake passage to the chioke valve. A vertical throttle valve type carburetor characterized in that the flange portion of the upper valve shaft is urged downward by a cover plate fitted and integrated with the boss portion and superposed and coupled to the upper wall surface of the carburetor body. . 3. A pair of grooves formed in the upper wall portion of the carburetor body, the groove having one end communicating with the inlet end of the intake passage and the other end communicating with the outlet opening to the top wall of the fuel chamber. The vertical throttle valve type carburetor according to claim 1, wherein a vent passage is provided, and the vent passage is covered with the cover plate. 4. The pair of vent passages have a right inlet communicating with an outlet of a left portion of the fuel chamber, a left inlet communicating with an outlet of a right portion of the fuel chamber, and an upper wall of a carburetor body. The vertical throttle valve type carburetor according to claim 1 or 2, wherein a pair of vent passages intersect each other. 5. The vertical throttle valve type carburetor according to claim 1, wherein a rib integrally formed with the cover plate is screwed with a bolt for adjusting an idle position of the throttle valve. 6. The vertical throttle valve type carburetor according to claim 1, wherein the spring comprises a plurality of pawls provided at a lower end of the chain yoke valve and contacting an inner peripheral surface of an intake passage. 7. The vertical throttle valve type carburetor according to claim 1, wherein the shape of the float axially supported by the fuel chamber so as to be swingable is such that the capacity increases as the distance from the shaft support increases. 8. The vertical throttle valve type carburetor according to claim 1, wherein the float has a lid bonded to a portion having a small bonding area apart from the shaft supporting portion. 9. A low speed fuel chamber in a lateral direction is provided on a side wall portion of the low speed fuel injection hole provided in the vicinity of the throttle valve, and a fuel adjusting member for adjusting a passage area is fitted into the low speed fuel chamber to insert the low speed fuel chamber. The vertical throttle valve type carburetor according to claim 1, wherein a low-speed fuel passage is provided which opens from the fuel chamber to a portion of the intake passage downstream of the throttle valve. 10. The low speed fuel chamber in which the fuel adjusting member is fitted and inserted is formed into a taper hole that expands outward.
The vertical throttle valve type carburetor described in. 11. A mounting bolt for mounting a carburetor main body to an engine, being parallel to an intake passage and arranged so as to intersect an outer end portion of the fuel adjusting member. Vertical throttle valve type carburetor.