JP2002256975A - Rotary throttle valve type carburetor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotary throttle valve type carburetor small in the number of parts, capable of setting fuel quantity so as not to exceed an exhaust gas regulating value at the time of factory delivery and easy in cold starting operation of an engine. SOLUTION: A throttle valve 12 having a throttle hole 20 is fitted in a valve chest 17 orthogonal with an air inlet passage 34 laterally passing a carburetor main body 33 free to revolve and axially move, and a needle 15 supported on the throttle valve 12 to adjust opening of a fuel nozzle hole 19 is fitted and inserted into a fuel supply pipe 18 projected to the throttle hole 20 from a fuel chamber. A follower 29 supported on the throttle valve 12 is engaged with a cam plate 10 free to revolve around a valve stem 43 of the throttle valve 12 as its center. The cam plate 10 is connected to a starting lever 72 of an axis of revolution 67 supported on the carburetor main body 33. A lock lever 63 revolved by the starting lever 72 against force of a spring 68 is engaged with a projected piece 2a provided on a throttle valve lever 2, and the throttle valve 12 is held at a fuel increasing position.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates mainly to a rotary throttle valve carburetor for an internal combustion engine mounted on a portable working machine such as a brush cutter, and more particularly to a rotary throttle valve carburetor having improved cold startability of the engine. It is about a vessel.

[0002]

2. Description of the Related Art In a conventional rotary throttle valve type carburetor disclosed in Japanese Patent Application Laid-Open No. 7-217500, a rich air-fuel mixture is supplied when the engine is started. When the atmospheric temperature reaches 10 ° C. below the freezing point, the engine suddenly violates, but the rotating state may not be maintained. In order to obtain a smooth start of the engine, the opening of the throttle valve must be slightly increased, and the starting operation is troublesome. Further, even if the opening of the throttle valve suitable for cold start of the engine is set, it is difficult to obtain a smooth start of the engine corresponding to a wide range of atmospheric temperature at one set point.

[0003]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, the object of the present invention is to reduce the number of parts, to set the fuel amount so as not to exceed the exhaust gas regulation value at the time of factory shipment, and to facilitate the cold start operation of the engine. Another object of the present invention is to provide a rotary throttle valve type carburetor.

Another object of the present invention is to provide a rotary throttle valve carburetor in which a remote control cable can be easily connected to a throttle valve lever housed in a closed housing.

[0005]

According to the present invention, a throttle valve having a throttle hole is rotatably and axially moved in a valve chamber orthogonal to an intake passage passing through a carburetor body. A needle supported by the throttle valve is inserted into a fuel supply pipe which is fitted as possible and protrudes from the fuel chamber to the throttle hole, and the opening of the throttle hole is adjusted by turning a throttle valve lever connected to the throttle valve. A rotary throttle valve carburetor that adjusts the opening degree of a fuel injection hole of the fuel supply pipe by axial movement of the throttle valve lever, wherein the cam plate is rotatable about a valve shaft of the throttle valve. Engage the follower supported by the throttle valve,
The cam plate is connected to a starting lever of a rotating shaft supported by the carburetor body via a link, and a lock lever rotated by the starting lever against the force of a spring is provided on the throttle valve lever. The throttle valve is configured to engage with the protruding piece to hold the throttle valve at the fuel increasing position.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, the opening of the throttle valve is slightly increased at the time of cold start of the engine so that the rotation after the start is continued. Two throttle valves are provided so that the engine can be started smoothly in response to a wide range of atmospheric temperatures. Of course, the starting fuel supply amounts are different at the two set points, and the engine can be started very easily by selecting one of the two set points according to the atmospheric temperature. When the warm-up is completed after starting the engine, the starting mechanism is returned to the old position. That is, the starting lever is returned to the old position by lightly snapping the throttle valve lever.

In the present invention, the throttle valve lever is housed in a sealed housing so that dust and muddy water do not enter into a movable portion such as a valve shaft of the throttle valve lever, and the inner wire of the remote control cable is throttled. Make it easy to connect to the lever.

[0008]

1 is a front sectional view of a rotary throttle valve carburetor according to the present invention, and FIG. 2 is a plan sectional view of the rotary throttle valve carburetor. In the carburetor body 33 through which the intake passage 34 passes, a cylindrical valve chamber 17 orthogonal to the intake passage 34 is provided, and the throttle valve 12 having the throttle hole 20 in the valve chamber 17 is rotatably and vertically movable. Be mounted. A not-shown, preferably film-type constant-pressure fuel chamber (not shown) is connected to the bottom wall of the vaporizer main body 33. The fuel supply pipe 18 is connected to the shaft 22 of the bottom wall of the vaporizer main body 33.
The throttle valve 12 is formed with a cylindrical portion 21 which is fitted on the shaft portion 22 and communicates with the throttle hole 20. The constant pressure fuel chamber communicates with the fuel supply pipe 18 via the fuel passage 23. A fuel injection hole 19 is formed at the upper end of the fuel supply pipe 18, and a fuel adjustment needle 15 projecting downward from the valve shaft 43 of the throttle valve 12 is fitted.

A cylindrical housing 32 is superimposed on the upper wall of the vaporizer main body 33, and is fixed by a plurality of bolts 79 (see FIG. 2). A boss 41 integral with the bottom wall 45 is provided at the axis of the housing 32, and the valve shaft 43 is rotatably fitted to the boss 41. The throttle valve lever 2 is coupled to the upper end of the valve shaft 43, and one end (left half of the figure) of the throttle valve lever 2 has an arc-shaped guide groove for guiding the inner wire 56 of the remote control cable 50 (FIG. 2). A locking hole 4 for locking the end retaining piece of the inner wire 56 is formed.
The inner wire 56 is wound around a guide groove on the peripheral wall of the fan-shaped throttle valve lever 2 and protrudes outside the housing 32. The upper end of the housing 32 is a lid 3 made of a transparent material.
Closed by 1.

The upper end of the return spring 6 lightly wound around the boss 41 is engaged with the throttle valve lever 2 and the lower end thereof is engaged with the bottom wall 45, respectively. By the force of the return spring 6, the throttle valve lever 2, the valve shaft 43 and the throttle valve 12 are urged to rotate to the idle position.
At this time, a protruding piece 2a protruding rightward from the throttle valve lever 2
Abuts on an idle adjustment bolt 62 screwed into the protruding wall portion 32 a of the housing 32. Further, the follower 29 is pressed against the cam plate 10 constituting the cam mechanism. Valve shaft 43
The base end of the fuel adjustment needle 15 is screwed into the inner space 42 of the fuel cell and closed by the stopper 3. Fuel adjustment needle 15
The coil spring interposed between the base end of the fuel shaft and the inner space 42 of the valve shaft 43 suppresses the loosening of the screwing portion of the base end of the fuel adjustment needle 15. Notches 13 are provided at both ends of the plate-like lever 16 connected to the lower end of the valve shaft 43. The notch 13 is engaged with a pair of pins 46 having a follower 29 supported on the upper end of the throttle valve 12 inside a circular recess 14 provided in the upper end wall of the throttle valve 12.

As shown in FIG. 2, according to the present invention, an idle adjusting bolt 62 is screwed and supported on the projecting wall portion 32a of the housing 32, and the tip of the idle adjusting bolt 62 is a projecting piece formed on the throttle valve lever 2. 2a.
Further, the low-speed fuel adjustment bolt 71 is screwed and supported by the protruding wall portion 32a. The head of the idle adjustment bolt 62 and the projecting wall 32
A coil spring for preventing the idle adjustment bolt 5 from being loosened is interposed between the coil spring a. Similarly, a coil spring that prevents loosening of the low-speed fuel adjustment bolt 71 is interposed between the cylindrical head of the low-speed fuel adjustment bolt 71 and the protruding wall portion 32a. The low-speed fuel adjustment bolt 71 is integrally formed with a cylindrical cover. When the cover comes into contact with the protruding wall portion 32a, the low-speed fuel adjustment bolt 71 cannot be further screwed.

A starting lever 72 is coupled to a lower end of a rotating shaft 67 supported on the protruding wall 32a. An operation lever 67 a is fastened to the upper end of the rotating shaft 67 by a bolt 66. The starting lever 72 is provided with a pressing piece 71a bent upward, and the pressing piece 71a is pressed by the lock lever 63 and abuts on the tip of the low-speed fuel adjusting bolt 71. Rock lever 63
Is rotatably supported by the rotating shaft 67, and the upper end of the spring 68 wound around the rotating shaft 67 is locked to the protruding wall portion 32 a, and the lower end is locked to the locking lever 63. The lock lever 63 is urged to rotate clockwise in FIG. The notch 63 is provided with two notches 63a and 63b which can be engaged with the protruding piece 2a at the leading edge of the lock lever 63. As shown in FIG. 1, the upper end of the pin 61 fixed to the cam plate 10 is connected to the housing 3 through the arc-shaped long hole 61 a of the bottom wall 45.
2 and is connected to the left end of the link 64. The right end of the link 64 is a starting lever 72 by a pin 70.
Linked to

The remote control cable 50 is connected to the outer tube 5.
3 is formed by inserting an inner wire 56. The outer tube 53 is screwed into a screw hole of the protruding wall 32b of the housing 32, and is fitted and supported by a metal support cylinder 54 fastened by a locking nut 54a. Outer tube 53 of projecting wall 32b of housing 32 of inner wire 56
Are covered with a dust cap 52.

Next, the operation of the rotary throttle valve type carburetor according to the present invention will be described. Before starting the engine,
When the operating lever 67a is turned in the counterclockwise direction, the pushing piece 72a of the starting lever 72 pushes the locking lever 63 to push the protruding piece 2a and turn in the counterclockwise direction. When the operating lever 67a is released, as shown in FIG. 3, the lock lever 63 is returned by the force of the spring 68, and the first notch 63a engages with the protruding piece 2a. The selective engagement of the notch 63a and the notch 63b with the protruding piece 2a is performed by operating the operating lever 67a.
Is achieved by the amount of rotation.

When the projecting piece 2a comes into contact with the idle adjustment bolt 62 from the idle position, the throttle valve lever 2 is moved in the direction of the arrow x in FIG.
The throttle valve 12 is also rotated in the same direction via the lever 16 at the lower end of the valve shaft 43, and the intake passage 34 of the throttle hole 20 is rotated.
Is increased. At the same time, the link 64 is pulled by the starting lever 72, and the cam plate 10 rotates counterclockwise about the boss 41. At this time, the throttle valve 12 and the fuel adjustment needle 15 move up together with the follower 29 engaging with the pair of cam surfaces 10 a formed point-symmetrically with respect to the center of the valve shaft 43, and the fuel injection hole 19 of the fuel supply pipe 18 is The opening increases.

Line n in FIG. 4 indicates the normal idle position of the throttle valve 12, and line c1 indicates the idle position of the throttle valve 12 when the notch 63a of the lock lever 63 is engaged with the projection 2a of the throttle valve lever 2. Line c2 indicates the idle position of the throttle valve 12 when the notch 63b of the lock lever 63 is engaged with the projection 2a of the throttle valve lever 2, respectively.

As described above, the opening degree of the throttle hole 20 of the throttle valve 12 and the opening degree of the fuel injection hole 19 are increased by the rotation of the throttle valve lever 2 and the operation lever 67a. A suitable rich mixture is obtained. When the engine is cranked, the fuel in the constant pressure fuel chamber is supplied to the fuel passage 23 and the fuel supply pipe 18.
The fuel is supplied to the intake passage 34 through the fuel injection hole 19 and the throttle hole 20, so that the engine can be started smoothly.

After the engine is started, when the starting lever 72 is returned to the old position by the operation lever 67a, the cam plate 10 returns to the old position. Pull the inner wire 56 further to open the throttle valve lever 2
2 (snap operation) in the direction of arrow x in FIG. 2, the notch 63 a of the locking lever 63 is disengaged from the projection 2 a of the throttle valve lever 2, and the locking lever 63, the starting lever 72, and the operating lever 67 a Return to the old position under the force. The cam plate 10 also returns to the old position.

In the present invention, the valve shaft 43 and the throttle valve 12 are formed separately, and the lever 16 at the lower end of the valve shaft 43 is
Is engaged with the pair of pins 46 supported on the valve shaft 43.
When the throttle valve 12 is rotated by the throttle valve lever 2, even if a force that tilts the valve shaft 43 is applied, the tilt of the valve shaft 43 is reduced.
The throttle valve 12 smoothly rotates inside the valve chamber 17 while always maintaining concentricity with the valve chamber 17.

Even if the valve shaft 43 is lengthened in order to mount the return spring 6, the throttle valve 12 is still operated by the throttle valve lever 2.
Is not adversely affected by movements that can cause them to fall. Valve shaft 4
Even when the throttle valve 3 is formed of a synthetic resin, the throttle valve 12 is not affected by the shape change due to the temperature of the valve shaft 43.

Only the valve shaft 43 can be detached from the carburetor main body 33, so that the fuel and air adjusting portions of the carburetor can be easily disassembled and cleaned.

The cam plate 10 is in contact with the lower surface of the bottom wall 45 of the housing 32, and a pair of followers 29 projecting from the upper end of the throttle valve 12 engage with the cam plate 10, so that the valve shaft 43 is provided.
The smooth operation of the cam mechanism can be obtained without being affected by the inclination of the cam mechanism.

[0023]

According to the present invention, as described above, a throttle valve having a throttle hole is rotatably and axially fitted in a valve chamber orthogonal to an intake passage passing through the carburetor body, and is inserted from the fuel chamber. A needle supported by the throttle valve is inserted into a fuel supply pipe protruding into the throttle hole, and the opening of the throttle hole is adjusted by turning a throttle valve lever coupled to the throttle valve, and a shaft of the throttle valve lever is adjusted. In a rotary throttle valve type carburetor for adjusting the opening of a fuel injection hole of the fuel supply pipe by moving, a follower supported by the throttle valve is engaged with a cam plate which is rotatable around a valve shaft of the throttle valve. The cam plate is connected to a starting lever of a rotating shaft supported on the carburetor body via a link, and a locking lever rotated by the starting lever against the force of a spring is connected to the throttle valve lever. Engage with the projecting piece provided and increase the throttle valve fuel Are those configured to hold the can driver without exceeding the emission control value to adjust the low-speed fuel quantity by slow fuel adjusting bolt in response to the ambient temperature.

A pin projecting from the cam plate through the elongated hole of the bottom wall of the housing to the inside of the housing is connected to a starting lever via a link. When the starting lever is rotated, the notch of the lock lever and the protrusion of the throttle valve lever are projected. Engagement with the piece is achieved,
The cam plate rotates to maintain the fuel increasing position suitable for cold starting of the engine.

Since the opening of the throttle hole and the opening of the fuel injection hole at the idle position can be separately adjusted, an appropriate air-fuel ratio can be set for the entire operation range.

A groove for guiding the inner wire of the throttle valve lever is provided at the back of the housing, and the operating portion of the throttle valve is completely sealed by the housing, so that foreign matter and muddy water can be prevented from entering the inside of the vaporizer. Can be prevented.

The throttle valve lever is provided with a hole for engaging the tip locking portion of the inner wire, and a groove for inserting the tip locking portion of the inner wire into the hole is provided on the peripheral wall of the hole. By simply inserting the inner wire from the opening of the housing, the distal end locking portion of the inner wire can be locked to the throttle valve lever.

[Brief description of the drawings]

FIG. 1 is a front sectional view of a rotary throttle valve carburetor according to the present invention.

FIG. 2 is a plan sectional view of the rotary throttle valve type carburetor.

FIG. 3 is a plan view showing a relationship between a protrusion of a throttle valve lever and a lock lever in the rotary throttle valve carburetor.

FIG. 4 is a plan sectional view showing a relationship between an intake passage and a throttle valve in the rotary throttle valve carburetor.

[Explanation of symbols]

2: throttle valve lever 2a: projecting piece 4: locking hole 4a: axial groove 6: return spring 10: cam plate 12: throttle valve 13: notch 15: fuel adjusting needle 16: lever 17: valve chamber 18: fuel Supply pipe 19: Fuel injection hole 20: Restriction hole 21: Cylindrical part 23: Fuel passage 29: Follower 31: Lid 32:
Housing 32a: Projecting wall 33: Vaporizer main body 32
b: Projecting wall 34: Intake path 41: Boss 43: Valve shaft 53: Outer tube 56: Inner wire 61: Pin 61a: Slot 62: Idle adjustment bolt 63: Lock lever 63a: Notch 63b: Notch 64: Link 66: Bolt 67 ： Rotating shaft 67
a: Operation lever 68: Spring 70: Pin 71: Low-speed fuel adjustment bolt
72: Starting lever 72a: Pressing piece

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) F02M 9/12 F02M 9/12 BC

Claims (5)

[Claims] 1. A throttle valve having a throttle hole is rotatably and axially fitted in a valve chamber orthogonal to an intake passage passing through a carburetor body, and a fuel supply projecting from the fuel chamber to the throttle hole. A needle supported by the throttle valve is inserted into the pipe, the opening of the throttle hole is adjusted by turning a throttle valve lever connected to the throttle valve, and the fuel in the fuel supply pipe is moved by the axial movement of the throttle valve lever. In a rotary throttle valve type carburetor for adjusting the opening degree of an injection hole, a follower supported by the throttle valve is engaged with a cam plate rotatable around a valve shaft of the throttle valve, and a link is formed between the cam plate and the link. And a locking lever pivoted by the starting lever against the force of a spring is engaged with a projection provided on the throttle valve lever. The throttle valve is configured to be held at a fuel increasing position. Rotary throttle valve type carburetor, characterized in that. 2. An end of a return spring wound around the rotating shaft is locked to the carburetor body, and the other end of the return spring is locked to the starting lever, and the starting lever is pressed against the force of the return spring. 2. The rotary throttle valve carburetor according to claim 1, wherein the lock lever engages with a protrusion of the throttle valve lever at the opening position of the throttle valve when the throttle valve is rotated. 3. The throttle valve lever according to claim 1, wherein said lock lever is provided with first and second notches for engaging with a projecting piece of said throttle valve lever, and said throttle valve lever is rotated when said starting lever is rotated against the force of said return spring. 2. The rotary throttle valve type carburetor according to claim 1, wherein the locking piece engages with the projection of the lock lever from the first notch to the second notch and locks. 4. A low-speed fuel adjusting bolt which abuts on a pushing piece of the starting lever and an idle adjusting bolt which abuts on a projecting piece of the throttle valve lever, are screwed into a projecting wall portion of a housing accommodating the throttle valve lever. The rotary throttle valve type carburetor according to claim 1, wherein 5. A groove for guiding an inner wire of the throttle valve lever is provided in a deep portion of the housing, and a hole is provided in the throttle valve lever for engaging a tip locking portion of the inner wire.
2. The rotary throttle valve carburetor according to claim 1, wherein an axial groove of the hole for inserting the tip locking portion into the hole is provided on a peripheral wall of the hole. 3.