JP2000064907A - Rotary throttle valve type carburetor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotary throttle valve type carburetor in which the workability of a throttle valve is excellent and looseness is hardly generated in a swivel attached to an operating lever. SOLUTION: A holder chamber 16 is arranged in the shaft hole 15 of the operating shaft 11 of a rotary throttle valve 6 formed on a cover 7, and also a sliding split 23 in a rotary axial line YY direction leading from an upper end to the holder chamber 16 is arranged to the operating shaft 11 of the rotary throttle valve 6. On the operating shaft 11, a jet needle holder 18 having a piston part 26 stored in the inside of the operating shaft 11, a flange part 27 arranged on the periphery of a valve shaft and an arm part 28 connecting the piston part 26 and the flange part 27 to each other and also engaged with the sliding split 23 is slidably fitted in a shaft direction, a cam surface 17 is arranged to one of the bottom surface of the holder chamber 18 or the lower surface of the flange part 27, and a pin 35 projected toward the cam surface 17 is arranged to the other thereof. Hereby, only a jet needle is vertically moved against the rotation of the throttle valve 6, and the engagement position of a cable wire with an operating lever is prevented from being vertically changed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary throttle valve type carburetor often used for small engines.

[0002]

2. Description of the Related Art Conventionally, in such a carburetor, a throttle valve having a throttle hole corresponding to the intake passage is rotatably arranged at right angles to an intake passage penetrating a carburetor body. The throttle valve is moved upward along with the rotation, and a jet needle attached to the throttle valve is moved within a fuel nozzle protruding from the throttle hole to control the amount of fuel injected. Further, a lever for engaging a cable wire is provided on an operation shaft of the throttle valve,
The lever moves up and down integrally with the throttle valve as the throttle valve rotates. (Jun 61-21562
No.)

However, while the cable wire engaged with the lever is pulled in the horizontal direction, the position of the lever changes in the vertical direction simultaneously with the rotation, so that the engagement state of the cable wire and the lever is changed. Become diagonal. That is, the engagement between the cable wire and the swivel rotatably attached to the lever and engaging the cable wire becomes oblique, thereby deteriorating the operability of the throttle valve and attaching the swivel to the operation lever. However, there is a problem that play is easily generated.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a rotary throttle valve type carburetor which has good operability of a throttle valve and does not cause backlash on a swivel mounted on an operation lever.

[0005]

A rotary throttle valve type carburetor in which a throttle valve having a throttle hole corresponding to the intake passage is rotatably arranged orthogonally to an intake passage passing through the carburetor body. An operation shaft formed so as to protrude upward from the throttle valve penetrates a cover attached to the upper portion of the vaporizer main body, and a holder chamber is provided on a through hole of the operation shaft of the cover. A slit is provided to reach the holder chamber. The operation shaft has a piston portion housed in the operation shaft, a flange portion arranged on the outer periphery of the valve shaft,
A jet needle holder having a piston portion and a flange portion, and an arm portion engaging with the slit, is vertically movably fitted, and a jet needle is screwed onto the piston portion of the jet needle holder. A cam surface is provided on one of the bottom surface or the flange lower surface of the holder chamber, and a pin protruding toward the cam surface is provided on the other, and the holder is urged toward the holder chamber bottom surface on the flange upper surface of the jet needle holder. Dispose the spring.

Accordingly, only the jet needle holder and the jet needle attached to the jet needle holder move up and down in response to the rotation of the throttle valve, so that the operation lever of the throttle valve only rotates, and the operation lever and the cable are moved. Since the engagement state of the wire is not oblique, the operability of the throttle valve is improved, and
The play of the swivel that is attached to the operation lever and engages the cable wire can be suppressed.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention provides a rotary throttle valve having a holder chamber provided in a shaft hole of an operating shaft of the rotary throttle valve formed in a cover, and an axial direction extending from an upper end to the holder chamber of the operating shaft of the rotary throttle valve. No cutting is provided. The operating shaft has a piston portion housed in the operating shaft, a flange portion arranged on the outer periphery of the valve shaft, and an arm portion connecting the piston portion and the flange portion and engaging with the slit. A jet needle holder is slidably fitted in the axial direction.Furthermore, a jet needle is screwed into a piston portion of the jet needle holder, and a cam surface on one of a bottom surface or a flange lower surface of the holder chamber and a cam surface on the other. A pin protruding toward the cam surface is provided, and a spring for urging the holder toward the holder chamber bottom surface is provided on the upper surface of the flange of the jet needle holder.

[0008] Further, if a protruding piece is provided inside the fitting hole of the operating lever attached to the upper end of the operating shaft, the protruding piece is fitted to the slit, so that the sliding can be prevented from being deformed in a narrowing direction. The rotation of the operation lever can be prevented.

When the slit of the operation shaft is exposed outside the vaporizer, a seal member is put on the operation shaft to prevent dust and rainwater from entering the inside of the vaporizer from the slit.

[0010] The operating lever may be provided with a cylindrical portion projecting downward and covering the periphery of the operating shaft to a predetermined position, thereby preventing exposure of the slit. In this case, if a projection is provided on the inner surface of the cylindrical portion to be fitted to the slide,
It is possible to prevent the slit from being deformed in the narrowing direction, to maintain good slidability of the jet needle holder engaging with the slit, and to prevent the operation lever from rotating.

As a method of incorporating a jet needle holder and a spring into the holder chamber, an upper part of the holder chamber is opened, and after the jet needle holder and the spring are accommodated, a lid is press-fitted into the opening, press-fitted or pressed. By attaching with screws or the like, closing the opening at the upper part of the holder chamber and pressing the other end of the spring,
The jet needle holder is held in a state of being urged downward.

[0012]

An embodiment of the present invention will be described below with reference to the drawings. 1 to 5, reference numeral 1 denotes a rotary throttle valve type carburetor, and an intake passage 3 is provided through a body 2;
A cylindrical throttle valve chamber 4 is provided at right angles in the middle of the intake passage 3. The throttle valve chamber 4 rotatably accommodates a cylindrical throttle valve 6 having a throttle hole 5 that matches the intake passage 3 when fully opened. A spring 8 disposed between the cover 7 closing the upper end of the throttle valve chamber 4 and the throttle valve 6
This urges the throttle valve 6 in the closing direction and urges it downward. At the bottom of the throttle valve chamber 4, a fuel nozzle 9 stands upright on the rotation axis YY of the throttle valve 6. The base end of the fuel nozzle 9 is connected to a fuel chamber (not shown) via a main jet (not shown). At the bottom of the throttle valve 6, an insertion hole 10 for the fuel nozzle 9 is provided on the rotation axis YY, and the fuel nozzle 9 protrudes into the throttle hole 5 through the insertion hole 10. An operation shaft 11 protruding upward from the upper part of the throttle valve 6 penetrates the cover 7, and an operation lever 12 is attached to an outer end. A swivel 13 for engaging a cable wire (not shown) with the operation lever 12
Is provided.

On the operation shaft hole 15 of the cover 7, there is provided a holder chamber 16 opening upward.
A cam surface 17 which is inclined upward in the valve opening direction of the throttle valve 6 is provided at the bottom of the throttle valve 6. The holder chamber 16
Is closed by a lid 20 after accommodating a later-described jet needle holder 18 and a spring 19.

The operating shaft 11 is provided with a guide chamber 22 having a bottom and opening upward, and a slot 23 extending from the upper end to the holder chamber 16 along the rotation axis YY. At the bottom of the guide chamber 22, a jet needle insertion hole 24 penetrating into the upper wall of the throttle hole 5 is provided.

The operating shaft 11 has a piston 26 accommodated in the guide chamber 22, a flange 27 disposed on the outer periphery of the operating shaft 11, a connection between the piston 26 and the flange 27, and A jet needle holder 18 having an arm portion 28 engaged with the split 23 is fitted. The jet needle holder 18 is interlocked with the rotation of the throttle valve 6 and slides along the rotation axis YY. Is possible.

A screw hole 30 is formed in the piston portion 26 of the jet needle holder 18 coaxially with the rotation axis YY of the throttle valve 6.
Is screwed. The jet needle 3
1 is projected from the jet needle insertion hole 24 to the throttle hole 5 and inserted into the fuel nozzle 9. By disposing a spring 33 between the screw portion 32 of the jet needle 31 and the bottom of the screw hole 30 of the jet needle holder 18, the jet needle 31 is prevented from loosening. In addition to the above, the prevention of the loosening
It is also possible by making the screwing state of the screw hole 30 and the screw hole 30 firm.

A pin 35 projecting toward the cam surface 17 is provided on a lower surface of the flange 27 of the jet needle holder 18.
And a spring 19 for urging the jet needle holder 18 downward and bringing the pin 35 into contact with the cam surface 17 is disposed between the flange 27 and the lid 20. When the jet needle holder 18 is rotated in conjunction with the throttle valve 6 by the engagement between the cam surface 17 and the pin 35, the jet needle holder 18 moves in the opening direction of the throttle valve 6 along the cam surface 17. Is moved upward when rotating, and downward when rotating in the closing direction, whereby the jet needle 31 moves up and down in the fuel nozzle 9 in response to the rotation of the throttle valve 6. That is, when the throttle valve 6 is rotated, the matching area between the throttle hole 5 and the intake passage 3 is increased or decreased, and the opening degree of the fuel injection port 37 is increased or decreased due to the vertical movement of the jet needle 31. Is injected into the throttle hole 5.

Jet needle 3 to the fuel nozzle 9
In this embodiment, as a method of controlling the amount of fuel ejected from the fuel nozzle 9 by the insertion position of the fuel nozzle 9,
A fuel injection hole 37 is formed in the side surface of the fuel nozzle 9, and the tip of the jet needle 31 inserted into the fuel nozzle 9 with almost no gap is moved on the fuel injection hole 37.
The fuel injection amount is controlled by changing the opening area of the fuel cell 7. As another embodiment, as shown in FIG. 7, a jet portion 40 is provided on the inner surface of the fuel nozzle 9, and a rod-shaped jet needle 31 is inserted into the jet portion 40 with a gap, and the jet portion 40 is inserted. The fuel is controlled by the amount of insertion of the jet needle 31 into the jet needle 31 or, as shown in FIG. It is also possible to control the fuel by the gap with the jet part 40 formed on the inner surface of the nozzle 9.

The operation lever 12 is provided with a hole 43 connected to the guide chamber 22 of the operation shaft 11 from the upper surface. The screw portion 32 of the jet needle 31 is rotated from the hole 43 to project the amount of projection of the jet needle 31. , That is, the fine adjustment of the fuel nozzle opening degree of the fuel nozzle by the jet needle 31 can be performed. A plug 44 that normally closes the hole 43 is fitted to the operation lever 12,
Intrusion of garbage, rainwater and the like into the guide room 22 is prevented. Further, the operating lever 12 has a protruding piece 46 fitted into the slide 23 inside a fitting hole 45 into which the operating shaft 11 is fitted.
Is provided to prevent the slit 23 from being deformed in a narrowing direction.

Further, by covering the operation shaft 11 exposed between the operation lever 12 and the cover 7 to the outside of the vaporizer with the seal member 47, it is possible to prevent dust and rainwater from entering the vaporizer from the slit 23. To prevent.

Next, the operation of the above configuration will be described. When the operating lever 12 is not operated, the throttle valve 6 is held at the idling opening degree by the action of the spring 8, the jet needle holder 18 is located at the lower limit, and the jet needle 31 moves the fuel injection port 37 of the fuel nozzle 9 to the minimum. It is opening.

When the throttle valve 6 is turned to the open side against the spring 8, the matching area between the throttle hole 5 provided in the throttle valve 6 and the intake passage 3 increases, and the amount of air flowing through the intake passage 3 decreases. To increase. With the rotation of the throttle valve 6, the jet needle holder 18 moves up along the cam 17, and the jet needle 31 increases the opening area of the fuel injection port 37.

When the throttle valve 6 is fully opened, the throttle hole 5 of the throttle valve 6 and the intake passage 3 completely match, the jet needle holder 18 is positioned at the upper limit, and the jet needle 31 is The fuel injection port 37 is set to the maximum opening.

In the above embodiment, the cam surface 17 is provided at the bottom of the holder chamber 16 and the pin 35 is formed so as to project downward from the flange 27 of the jet needle holder 18. However, as shown in FIG. Needle holder 18
Even if the cam surface 17 is provided on the lower surface of the flange 27 and the pin 35 is formed to project upward from the bottom of the holder chamber 16, the operation and effect of the present invention can be obtained in exactly the same manner.

In the above embodiment, the sealing member 4 is provided on the exposed portion of the operating shaft 11 provided with the slit 23 to the outside of the vaporizer.
7, the operation lever 12 is provided with a cylindrical portion 48 projecting downward and covering the periphery of the operation shaft 11 to a predetermined position, as shown in FIG.
Can be prevented from being exposed to the outside of the vaporizer. Also in this case, if the protrusion 49 is provided on the inner surface of the cylindrical portion 48 so as to be fitted to the slit 23, it is possible to prevent the slit 23 from being deformed in a narrowing direction, and the jet engaging with the slit 23 is provided. The slidability of the needle holder 18 can be kept good, and the operation lever 1 is
2 and the operation shaft 11 can be prevented from rotating.

[0026]

As described above in detail, according to the present invention, only the jet needle is moved up and down with respect to the rotation of the throttle valve, so that the actuating lever performs only a rotating operation without moving up and down. Therefore, the engagement between the swivel and the cable wire attached to the operation lever does not become oblique, the operability of the throttle valve is improved, and no play is generated on the shaft portion of the swivel. improves.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a throttle valve in a fully opened state according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along the line AA of FIG. 1, showing an engagement state between the operation shaft and the jet needle holder in the cover.

FIG. 3 is a sectional view taken along the line BB of FIG. 1 showing a cam surface provided at the bottom of the holder chamber.

FIG. 4C shows a state in which the operation shaft and the operation lever are fitted to each other.
FIG. 4 is a sectional view taken along line C of FIG.

FIG. 5 is an explanatory diagram showing an engagement state between a cam surface and a jet needle holder.

FIG. 6 is an explanatory view showing an engagement state between a cam surface and a jet needle holder in another embodiment.

FIG. 7 is a sectional view of a main part showing another embodiment of a fuel control method using a jet needle and a fuel nozzle.

FIG. 8 is a sectional view of a main part showing another embodiment of a fuel control method using a jet needle and a fuel nozzle.

FIG. 9 is a longitudinal sectional view showing another embodiment of the present invention in a state where a throttle valve is fully opened.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rotary throttle valve carburetor 3 Intake passage 5 Throttle hole 6 Throttle valve 7 Cover 9 Fuel nozzle 11 Operating shaft 12 Operating lever 16 Holder room 17 Cam surface 18 Jet needle holder 23 Slot 31 Jet needle 37 Fuel injection port

Claims (3)

[Claims] 1. A rotary throttle valve type carburetor in which a throttle valve having a throttle hole corresponding to the intake passage is rotatably arranged orthogonally to an intake passage penetrating the carburetor main body. An operation shaft projecting upward from the throttle valve penetrates a cover attached to the rotary throttle valve, and a holder chamber is provided on a through hole of the operation shaft of the cover. The operation shaft is provided with a piston portion housed in the operation shaft, a flange portion disposed on the outer periphery of the valve shaft, and a piston portion and a flange portion are connected and engaged with the slide portion. And a jet needle holder having a vertically movable arm, a jet needle is screwed onto a piston of the jet needle holder, and a bottom of the holder chamber or below the flange. A cam surface is provided on one of the surfaces, a pin protruding toward the cam surface is provided on the other surface, and a spring for urging the holder toward the holder chamber bottom side is provided on the upper surface of the flange portion of the jet needle holder. Rotary throttle valve carburetor. 2. The rotary throttle valve carburetor according to claim 1, wherein the operating lever is provided with a projecting piece that fits into a slot provided on the operating shaft. 3. A rotary throttle valve type carburetor according to claim 1, wherein said operating lever is provided with a cylindrical portion having a predetermined length fitted to an outer periphery of said operating shaft.