JP2668772B2 - Sliding throttle valve type carburetor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sliding throttle valve in which a throttle valve guide cylinder is formed so as to be connected to an intake passage penetrating a carburetor body and in which the intake passage is opened and closed. Is movably arranged, and in the starter valve guide cylinder, a starting air passage communicating with an intake passage upstream of the sliding throttle valve or the atmosphere and a starting mixing passage communicating with an intake passage downstream of the sliding throttle valve. The air passage and the starting fuel nozzle to which the starting fuel is supplied are opened, and the opening air passage and the starting air-fuel mixture passage are opened / closed by a start valve movably arranged in the start valve guide cylinder. The present invention relates to a sliding throttle valve carburetor provided with a starting device in which a starting needle valve mounted on a starting valve is inserted and arranged in a starting fuel nozzle.

[0002]

2. Description of the Related Art Conventionally, a sliding throttle valve which has a starter mechanism also serving as an idle adjusting mechanism to eliminate a factor of a decrease in intake efficiency and to expand a degree of freedom in arrangement and stabilize an air-fuel ratio at idling Type carburetor is Tokuhei 2-
No. 25022, which consists of the following. That is, a sliding throttle valve is slidably supported by the carburetor body to adjust the opening degree of the venturi portion of the intake passage provided in the carburetor body, and is provided for bypassing the venturi portion for starting. A starter mechanism provided with a starter valve slidable across the bypass for opening and closing the start-up bypass and an operating shaft integrated with the starter valve for manually operating the starter-valve in the middle of the bypass. In the sliding throttle valve type carburetor provided with, the starter valve of the starting mechanism is configured to be rotatable about an axis line along the sliding direction of the starting mechanism, and is opened in a starting bypass corresponding to the starter valve. Holding the jet needle that can be inserted into the idle adjustment fuel nozzle, the operation shaft is prevented from rotating around the axis with respect to the carburetor body, and is advanced or retracted in the direction along the axis. Screwed into volume has been slider, and more carburetor body, a stop portion is provided engageable with the slider in order to regulate the sliding limit to the closing side of the starter valve.

[0003]

The conventional sliding throttle valve carburetor has the following problems. A coil spring, a slider, a clip, which urges the starter valve in the closing direction, which is directed upward from the starter valve, and a spherical locking portion are further arranged in series on the operation shaft. Then, when the engine is started, the starter valve is pulled up by a predetermined distance H so that the spherical locking portion is supported by the seat, and the starter valve is moved from the minimum opening position to the full opening position. according to this,
The coil spring, the slider, the clip, and the spherical locking portion each require a space having a distance H in the longitudinal direction so that the movement of the fixed distance H is permitted. This is shown in the schematic diagram of FIG. According to the above, it is difficult to shorten the length in the longitudinal direction, and it is impossible to provide a compact vaporizer. A clip for controlling the rotation of the operating shaft and a receiving member as a stopper for engaging with the slider for restricting the movement limit of the starter valve are specially prepared, and the clip is fitted in a groove formed in the operating shaft. And the receiving member must be placed on the step. According to the above, the number of parts and the number of assembling steps are increased, which leads to an increase in the manufacturing cost of the vaporizer, which is not preferable. The slider is screwed to a screw portion formed below the operation shaft near the starter valve. Since this screw portion is below the operation shaft as described above, the method of screwing the slider is special. Must be taken into account. That is, since the starter valve having a large diameter is disposed below the screw portion, it is necessary to screw the slider to the screw portion from above the operation shaft, and the operation shaft above the screw portion has a smaller diameter than the screw portion. Need to be formed. The holding force of the clip for controlling the rotation of the operating shaft is performed by the bending force of the triangular portion. However, since this clip is disposed inside a relatively small holding cylinder, the setting operation of the bending force is easy. Cannot do it.

The sliding throttle valve type carburetor according to the present invention has been made in view of the above problems, and particularly by reducing the overall height (vertical longitudinal direction) of the starting device in which the starting mechanism also serves as the idle adjusting mechanism. It is to provide a compact sliding throttle valve type carburetor and to reduce its manufacturing cost by reducing the number of parts and the number of assembling steps.

[0005]

SUMMARY OF THE INVENTION To achieve the above object, the present invention provides an adjusting shaft for extending a start valve upward from a valve portion, a male screw formed at an upper end of the adjusting shaft, and an adjusting shaft. In the lower position, the locking protrusion having a diameter larger than the outer diameter of the adjusting shaft, attached to the adjusting shaft between the male screw and the locking protrusion, orthogonal to the longitudinal direction of the adjusting shaft, The adjusting knob is formed by a positioning sliding rod protruding laterally from the outer diameter of the adjusting shaft, and the adjusting knob has a polygonal cross-sectional shape, has an end surface at a lower end, and has a female screw hole extending inward along the longitudinal direction. Is formed by a shaft portion formed through the shaft portion and a knob portion attached to the upper end of the shaft portion, and the holder member forms a flat surface formed at a substantially middle portion inward in the longitudinal direction. It is said that it can be opened upward from the stop step and the locking step to accommodate the shaft of the adjustment knob. An adjustment knob housing hole in which a locking piece is formed by a plurality of slit grooves, and a locking projection formed on the upper end of the locking piece, the inner surface of which is in contact with the side of a polygonal shaft. An adjustment shaft insertion hole which opens downward from the locking step portion and through which the adjustment shaft of the start valve can be inserted, and is formed along the longitudinal direction of the adjustment shaft insertion hole to rotate the positioning sliding rod. It is formed by a positioning slide rod control groove that blocks movement and allows movement in the longitudinal direction, and a locking projection that is formed at the lower end of the adjustment shaft insertion hole and whose inner diameter is smaller than the outer diameter of the locking projection. The end surface of the shaft portion of the adjustment knob screwed to the male screw of the adjustment shaft is placed in contact with the locking step of the holder member, and the outer portion of the shaft portion is placed in contact with the locking projection of the holder member. The positioning slide rod is further disposed in the positioning slide rod control groove of the holder member so as to be movable in the longitudinal direction. Rutotomoni, the outer circumference of the locking projection of the adjusting shaft, one end is engaged with the holder member and the other end is characterized in that it is mounted under compression coil spring is engaged to the valve unit.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a sliding throttle valve type carburetor according to the present invention will be described below with reference to the drawings. FIG. 1 is a longitudinal sectional view of a sliding throttle valve type carburetor including a starting device. FIG. 2 is an enlarged vertical sectional view of the starting device in FIG. FIG. 3 is an enlarged cross-sectional view taken along line XX of FIG. FIG. 4 is an enlarged cross-sectional view taken along line YY of FIG. FIG. 5 is an enlarged cross-sectional view taken along the line ZZ of FIG.
Reference numeral 1 denotes a carburetor main body formed with an intake passage 2 penetrating laterally therethrough. A sliding throttle valve guide cylinder 3 is continuously provided upward from an intermediate portion of the intake passage 2 and an upper portion thereof opens. . Reference numeral 4 denotes a float chamber main body which is arranged below the vaporizer main body 1 so as to be in contact therewith. A float chamber 5 is formed by the lower concave portion of the vaporizer main body 1 and the float chamber main body 4, and the float chamber 5 has a float. The float valve 6 is disposed and the float valve moved by the float 6 opens and closes a valve seat disposed at the end of the fuel flow path, and forms and maintains a constant liquid level BB in the float chamber.
The float valve, valve seat, and fuel flow path are not shown. Reference numeral 7 denotes a needle jet that opens at the bottom of the intake passage 2, and this needle jet is communicated below a fixed liquid level BB in the float chamber 5 through a main fuel jet 8.
Reference numeral 9 is a bypass hole that opens at the bottom of the intake passage 2 downstream of the needle jet 7, and the bypass hole 9 is a constant liquid level BB in the float chamber 5 through a low speed fuel jet 10 equipped with a bleed tube. And a pilot outlet hole 1 at the bottom of the intake passage 2 downstream of the bypass hole 9.
1 is open, and this pilot outlet hole 11 is branched from a low speed fuel passage 12 which connects the low speed fuel jet 10 and the bypass hole 9. Reference numeral 13 denotes a sliding throttle valve which is movably arranged in the sliding throttle valve guide cylinder 3 and which is locked by an operation wire (not shown) operated by a driver to control opening / closing of the intake passage 2. At the center, a jet needle 14 protruding downward is mounted.

A jet needle 14 is inserted and arranged in the needle jet 7, and the bypass hole 9 has an end portion 13A on the downstream side of the sliding throttle valve 13 (in other words, an end portion on the engine side of the sliding throttle valve 13). The pilot outlet hole 11 is open to the intake passage 2 on the upstream side (right side in FIG. 1) from the left side in FIG.
3 and is opened to the intake passage 2A on the downstream side. Then, in a state where the sliding throttle valve 13 is moved to the lowest position, the intake passage 2 is held in a fully closed state by the sliding throttle valve 13.
FIG. 1 shows a fully closed state of the intake passage 2 by the sliding throttle valve 13. The sliding throttle valve carburetor is formed as described above.

[0008] The starting device S comprises the following. Reference numeral 20 denotes a starting device body in which a cylindrical starting valve guide cylinder 21 opening upward is provided, and one side wall of the starting valve guide cylinder 21 has an intake passage 2B upstream of the sliding throttle valve 13 or The starting air passage 22 communicating with the atmosphere is opened, and the starting valve guide cylinder 2 is opened.
1, the intake passage 2A downstream of the sliding throttle valve 13
The starting mixture passage 23 is opened, and the starting fuel nozzle 24 is opened at the bottom of the starting valve guide cylinder 21. The starting fuel nozzle 24 is located below the starting device body 20. The fuel in the starting fuel tank 25 arranged in the fuel tank is supplied via a starting fuel control jet 26. The starting fuel tank 25 is communicated with the lower part of the liquid level BB in the float chamber 5, and the fuel in the float chamber 5 is supplied. The starter body 20 is preferably formed integrally with the carburetor body 1, and the starter fuel tank 25 is preferably formed integrally with the float chamber body 4. Reference numeral 27 denotes a bleed air passage for atomizing the fuel controlled by the starting fuel control jet 26, and is communicated with the upper portion of the fixed liquid level BB of the float chamber 5 or the atmosphere.

Reference numeral 28 denotes a starting valve movably disposed in the starting valve guide cylinder 21. The starting valve 28 has an adjustment shaft 29 extending upward and formed integrally with a valve portion 28A. The start valve 28 controls the opening and closing of the openings of the starting air passage 22 and the starting mixture passage 23 in the outer peripheral portion of the valve portion 28A. The position of the starting valve 28 in FIGS. Air passage 22, starting mixture passage 23
In the fully closed state, the starting valve 28 moves upward from such a state, the openings of the starting air passage 22 and the starting mixture passage 23 gradually increase, and the starting valve 28 starts up. The starting air passage 2 passes through the air passage 22 and the starting mixture passage 23 upward.
2. The starting air-fuel mixture passage 23 is fully opened.

A starting needle valve 30 is integrally attached to the starting valve 28 along the longitudinal axis direction.
The starting needle valve 30 projects downward from the bottom of the starting valve 28 and is inserted and arranged in the starting fuel nozzle 24. The starting needle valve 30 has a large diameter portion 30A formed above and a small diameter portion 30B formed continuously below the large diameter portion 30A. The starting air passage 2 of the starting valve 28
2. The fully closed position state with respect to the starting air-fuel mixture passage 23 or the adjusted minimum opening position state (the starting valve 28 described later)
In the starting fuel nozzle 24, the large-diameter portion 3 of the starting needle valve 30 is provided.
0A is inserted and arranged, while the start valve 28 is in a high opening position state with respect to the start air passage 22 and the start air-fuel mixture passage 23,
Alternatively, in a fully open position state (a starting air-fuel mixture supplied state by a starting valve 28 described later), the small diameter portion 30A of the starting needle valve 30 is inserted and arranged in the starting fuel nozzle 24. In particular, the large diameter portion 30 of the starting needle valve 30
The gap formed by A and the starting fuel nozzle 24 must be formed as a very small gap. This minute gap means 100 microns or less. In this embodiment, the starting fuel nozzle 24 has an inner diameter of 2 mm, and the starting needle valve 30 has a large diameter portion 30A having an outer diameter of 1.95. Millimeters and the gap formed by them was 50 microns. The small diameter portion 30B of the starting needle valve 30 was 1 mm.

The adjusting shaft 29 is formed and mounted as follows. The adjusting shaft 29 has a diameter C, a male screw 29A is formed at the upper end thereof, a locking projection 29B is formed at a lower position near the valve portion 28A, and further between the male screw 29A and the locking projection 29B. The positioning sliding rod 30 is mounted.
The locking projection 29B has a spherical shape, and its outer diameter D is formed larger than the outer diameter C of the adjustment shaft 29. The positioning sliding rod 30 has a pin shape, is disposed orthogonally to the longitudinal direction of the adjusting shaft 29 (the vertical direction in FIG. 2), and both ends protrude outward from the adjusting shaft 29. .

Reference numeral 31 is a holder member that closes the upper opening 21A of the starter valve guide cylinder 21 to the upper end surface 20A of the starter body 20 and houses the starter valve 28, and is made of a synthetic resin material such as nylon. Formed. The following is formed inside the holder member 31. 31A is a locking step formed as a flat surface (perpendicular to the longitudinal direction) formed at an approximately middle portion on the inside. An adjustment knob accommodation hole 31B for accommodating a shaft portion of an adjustment knob described later is formed and opens upward from the locking step portion 31A. The adjustment knob storage hole 31B has a plurality of slit grooves 31C along the longitudinal direction.
Are formed, and a locking piece 31D is formed between the adjacent slit grooves 31C. In this embodiment, the slit groove 31C and the locking piece 31B are formed at three places.
A locking projection 31G is formed on the inner side surface 31F of the upper end 31E of the locking piece 31D to be in contact with the side of the polygonal shaft portion of the adjustment knob described later. That is, the inner side surface 31F of the locking projection 31G is formed inside the adjustment knob storage hole 31B. The locking projection 31G is better shown in FIG.

An adjustment shaft insertion hole 31H through which the adjustment shaft 29 can be inserted is penetrated downward from the locking step portion 31A. The adjustment shaft insertion hole 31H has a longitudinal direction ( 2 (in the vertical direction in FIG. 2)
J is drilled. The positioning sliding rod control groove 31J is opened at the lower opening end of the adjustment shaft insertion hole 31H.
In this embodiment, four positioning sliding rod control grooves 31J are formed. This positioning slide rod control groove 31J is well shown in FIG.

A locking projection 31K having a diameter smaller than the outer diameter D of the locking projection 29B of the adjustment shaft 29 is formed near the lower opening end of the adjustment shaft insertion hole 31H. That is, four holes are formed at the open ends of the adjusting shaft insertion holes 31H between the adjacent positioning sliding rod control grooves 31J. This locking projection 31K is well shown in FIG. The lower adjustment shaft insertion hole 31H in which the locking projection 31K is formed is attached to the holder member 3.
A short cylindrical portion 31L having a gap S with respect to one inner diameter portion 31M
Is preferable to obtain the locking holding force of the locking projection 31K.

Outside the holder member 31, there are formed a polygonal spanner hook 31N and a male screw 31P extending downward from the spanner hook 31N.

Reference numeral 32 is an adjustment knob formed by a shaft portion 33 and a knob portion 34. The shaft portion 33 has an end face 33A at its lower end and has a cross-sectional shape of a polygon such as a hexagon or a quadrangle. Inside, a female screw hole 33B is bored in the longitudinal direction (vertical direction in the figure). Since the shaft portion 33 has a polygonal shape, a side 33C is formed between adjacent vertices 33D of the polygon.

Then, the starting device S is assembled as follows. First, a positioning sliding rod 30 is press-fitted and arranged at right angles to the longitudinal direction at an intermediate portion of the adjustment shaft 29 of the starting valve 28. At this time, the positioning sliding rod 30 and the valve portion 28A The coil spring 35 is contracted. according to this,
The coil spring 35 is disposed so as to surround the outer periphery of the locking projection 29B of the adjustment shaft 29.

Second, the adjusting shaft 29 is inserted from the lower opening of the holder member 31 toward the adjusting shaft insertion hole 31H. The male screw 29A is inserted into the groove 31J, while the male screw 29A protrudes above the locking step 31A of the holder member 31. According to the insertion of the adjustment shaft 29, one end of the coil spring 35 is connected to the adjustment shaft insertion hole 31.
H will be locked at the open end.

On the other hand, the shaft portion 33 of the adjustment knob 32 is inserted from above the holder member 31 into the adjustment knob housing hole 31B. At this time, the female screw hole 33B of the adjustment knob 32 is rotated by rotating the adjustment knob. It is screwed onto a male screw 29A of the adjustment shaft 29 projecting upward from the locking step 31A.

According to the above, the starting valve 28 and the adjustment knob 32 can be integrally attached to the holder member 31.
Then, the polygonal side 33C of the shaft portion 33 of the adjustment knob 32
Is the locking projection 31G of the locking piece 31D of the holder member 31.
Is disposed so as to abut the inner side surface 31F of the shaft 3 and the end surface 3 of the shaft portion 33.
3A is arranged in contact with the locking step 31A of the holder member 31 by the spring force of the coil spring 35.

The positioning sliding rod 30 is movably disposed in the positioning sliding rod control groove 31J of the holder member 31. The locking projection 29B provided on the adjustment shaft 29 is disposed below the locking projection 31K of the holder member 31.

Next, the holder member 31 to which the starting valve 28 and the adjusting knob 32 are integrally attached is assembled to the main body 20 of the starting device. This is to guide the valve portion 28A of the starting valve 28 to the starting valve guide. This is performed by screwing the male screw 31P of the holder member 31 into the upper opening 21A of the start valve guide cylinder 21 while inserting it into the cylinder 21, and the assembly is completed and the starter S is formed. You.

Next, the operation will be described. First, the engine idling operation will be described. In such a state, the sliding throttle valve 13 does not receive the upward traction force by the driver, and the intake path 2 is maintained in the fully closed state. The idling air amount required for the idling operation is adjusted by rotating the adjustment knob 32.

That is, the end surface 33A of the shaft portion 33 of the adjusting knob 32 is constantly elastically pressed and arranged on the locking step portion 31A of the holder member 31 by the spring force of the coil spring 35, and the start valve 28 is adjusted. The shaft 29 is configured so that the positioning sliding rod 30 is positioned in the positioning sliding rod control groove 3 of the holder member 31.
The rotation of the adjustment shaft 29 including the start valve 28 is performed by rotating the adjustment knob 32 because the rotation is suppressed and the rotation in the longitudinal direction is allowed while being inserted into the 1J.
It moves in the longitudinal direction, ie, upward or downward.

When the adjusting knob 32 is rotated in one direction and the adjusting shaft 29 is moved upward, the starting valve 28 moves to the side where the starting air passage 22 and the starting mixture passage 23 are opened, and According to the downward movement of the adjustment shaft 29 due to the rotation of the adjustment knob 32 in the other direction, the start valve 28 moves to the side that closes the start air passage 22 and the start air-fuel mixture passage 23. Accordingly, the position of the starting valve 28 is controlled by appropriately rotating the adjustment knob in a desired direction, and the optimum amount of idling air for idling operation is slid through the starting air passage 22 and the starting air-fuel mixture passage 23. Dynamic throttle valve 1
3 can be supplied to the intake path 2 </ b> A on the downstream side.

When the driver rotates the adjustment knob 32 to adjust the opening degree of the start valve 28 as described above, the apex 33D of the polygonal shaft portion 33 of the adjustment knob 32 is engaged with the holder member 31. It passes through the inner side surface 31F of the stop projection 31G and the slit groove 31C, and when the apex 33D abuts the inner side surface 31F of the locking projection 31G, the rotation operation of the adjustment knob 32 is prevented. Gives a sense of resistance, while vertex 33D
Is released into the slit groove 31C, the sense of resistance is released.

Therefore, the rotational angle position of the adjusting knob 32 becomes clear to the operator, which is convenient for adjusting the idle opening degree.

The idling air amount is adjusted so that the side 33C of the shaft portion 33 of the adjustment knob 32 is fixed to the inner surface 3 of the locking projection 31G unless a rotational operation force is applied to the adjustment knob 32 again.
Because it is held at 1F, it does not rotate,
The adjusted idling air amount can be continuously supplied.

The pressure holding force of the locking projection 31G against the side 33C of the shaft portion 33 of the adjusting knob 32 is determined by the locking projection 3
A desired pressure holding force can be easily obtained by setting the bending deformation force and the rigidity force by pressing deformation against the side 33C of 1G, the thickness of the locking piece portion 31D on which the locking projection 31G is formed, and selection of the material. be able to.

Explaining the engine starting operation when the engine ambient temperature is low, the driver senses that the temperature is low, grasps the knob portion 34 of the adjusting knob 32, and resists the spring force of the coil spring 35. The adjustment knob 32 is towed upward, whereby the adjustment shaft 2 is moved.
The locking projection 29B provided on the plate 9 is formed by enlarging the locking projection 31K of the holder member 31 toward the outside and then locking the projection 31K.
And the positioning is stopped. Such an adjustment knob 32
The shaft portion 3 of the adjustment knob 32 in the upward movement of the tendon.
3, the movement is not hindered by the inner side surface 31F of the locking projection 31G and the adjustment knob storage hole 31B, and the positioning sliding rod 30 slides in the positioning sliding rod control groove 31J of the holder member 31. Since it moves, its movement is not hindered, and thus the starting valve 28 including the adjusting shaft 29 can move in synchronization with the adjusting knob 32.

The adjusting shaft 29 and the starting valve 28 move upward in synchronization with the adjusting knob 32, and the starting valve 28 holds the starting air passage 22 and the starting air-fuel mixture passage 23 in a fully open state. The large diameter portion 30A of the needle valve 30 protrudes upward from the inside of the starting fuel nozzle 24, and the small diameter portion 30B is arranged inside the starting fuel nozzle 24, and a large gap is formed by the small diameter portion 30B and the starting fuel nozzle 24. Is formed and held. In such a state, when the engine is started, a large negative pressure generated in the intake passage 2A downstream of the sliding throttle valve 13 acts on the starting air-fuel mixture passage 23, thereby starting the engine from the starting air passage 22. The starting air is sucked in and the starting fuel is sucked out of the large gap of the starting fuel nozzle 24 to form a starting mixture, and the increased starting rich mixture is supplied from the starting mixture passage 23. Intake path 2
A is supplied to the engine A, so that the engine can be started smoothly in a state where the engine ambient temperature is low.

When the warm-up operation of the engine is completed with the lapse of time after the start-up operation of the engine, the driver pushes the adjustment knob 32 downward and the engagement projection 29B of the adjustment shaft 29 and the holder member 31 are engaged. The starting valve 28 including the adjustment knob 32 moves downward together with the spring force of the coil spring 35 to release the bearing from the protrusion 31K, and the end surface 33A of the adjustment knob 32 is locked by the holder member 31. The downward movement of the starting valve 28 is stopped in a state where the starting valve 28 is in contact with the portion 31A again. The state in which the end surface 33A of the adjustment knob 32 is in contact with the locking step 31A of the holder member 31 adjusts the adjustment knob 32 in the above-described manner and adjusts the position of the start air passage 22 and the start air-fuel mixture passage 23 of the start valve 28. It is the lowest opening position and is in an idling state by the start valve 28. In such an idling state, the starting valve 28 is again turned on.
Thus, the starting air passage 22 and the starting mixture passage 23 supply the controlled idling air toward the intake passage 2A, while the large diameter portion 30A of the starting needle valve 30 enters the starting fuel nozzle 24. It is inserted again.

[0033]

As described above, the sliding throttle valve type carburetor according to the present invention has the following effects. A coil spring that urges the start valve in the closing direction is arranged on the outer circumference of the locking projection on the adjustment shaft, so that when the adjustment knob is towed upward during starting, And the compression stroke of the coil spring can be performed in parallel. According to the above, the moving stroke of the locking projection and the compression stroke of the coil spring are arranged in series as in the conventional case,
Compared to the case having each stroke in the vertical direction, it is possible to shorten the length in the longitudinal direction and provide a compact carburetor. The limit of movement of the starting valve in the closing direction is adjusted by the end surface of the adjustment knob and the locking step of the holder member, and the click feeling when the adjustment knob is rotated is determined by the polygonal shaft of the adjustment knob and the holder member. Therefore, the number of parts can be reduced. Further, the contact between the end surface of the adjustment knob and the locking step of the holder member and the engagement between the shaft portion of the adjustment knob and the locking protrusion of the holder member are extremely simple by assembling the adjustment knob to the holder member. The number of assembly steps can be reduced. The adjustment knob that adjusts the limit of movement of the starting valve in the closing direction is screwed onto the male screw formed on the upper end of the adjustment shaft, so there is no need to give special consideration to the screwing method. It can be carried out extremely easily and the screwing workability can be improved. Since the locking protrusion that holds the start valve in the fully open state is provided on the locking piece above the holder member, the holding force of the starting valve due to the contact between the shaft of the adjustment knob and the locking piece Is only necessary to appropriately set the pressing force of the locking projection against the shaft. This setting is based on the thickness, cantilever length, rigidity, and material of the locking piece on which the locking projection is formed. It can be done very easily by selecting
The degree of freedom of the setting can be greatly improved.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a sliding throttle valve carburetor including a starting device.

FIG. 2 is an enlarged vertical sectional view of the starting device in FIG.

FIG. 3 is an enlarged cross-sectional view taken along line XX of FIG.

FIG. 4 is an enlarged cross-sectional view taken along the line YY of FIG.

5 is an enlarged cross-sectional view taken along line ZZ in FIG.

FIG. 6 is a simplified diagram showing a relationship between operating strokes in a conventional starting device.

[Explanation of symbols]

 Reference Signs List 28 Start valve 28A Valve portion 29 Adjusting shaft 29A Male screw 29B Locking protrusion 30 Positioning sliding rod 31 Holder member 31A Locking step 31B Adjustment knob storage hole 31C Slit groove 31D Locking piece 31E Upper end of locking piece 31F Inner surface 31G Locking protrusion 31H Adjusting shaft insertion hole 31J Positioning sliding rod control groove 31K Locking protrusion 32 Adjusting knob 33 Shaft 33C Side 35 Coil spring

Claims (1)

(57) [Claims] 1. A sliding throttle valve for controlling opening / closing of an intake passage passing through a carburetor main body, an intake passage upstream of the sliding throttle valve or a starting air passage communicating with the atmosphere, and a downstream side of the sliding throttle valve. Of the starting air passage and the starting fuel nozzle to which the starting fuel is supplied are movably disposed in a starting valve guide cylinder, and the starting air passage and the starting air mixture passage are provided. A starting valve for controlling the opening of the starting fuel passage;
A sliding throttle valve type carburetor equipped with an adjusting knob attached to the upper end of the starting valve for operating the starting valve, and a holder member for closing the upper opening of the starting valve guide cylinder and accommodating the starting valve. An adjusting shaft 29 that extends the valve 28 upward from the valve portion 28A, a male screw 29A formed at an upper end of the adjusting shaft 29, and a position below the adjusting shaft 29 that is larger than the outer diameter of the adjusting shaft 29. A locking projection 29B having a diameter,
Formed by a positioning slide rod 30 which is attached to the adjusting shaft 29 between the male screw 29A and the locking projection 29B, is orthogonal to the longitudinal direction of the adjusting shaft 29, and projects laterally from the outer diameter of the adjusting shaft 29. The adjustment knob 32 has a shaft section 33 having a polygonal cross section, an end face 33A at the lower end, and a female screw hole 33B extending inward along the longitudinal direction.
And a knob portion 34 attached to the upper end of the shaft portion 33, and the holder member 31 is formed by a locking step portion 31 </ b> A having a flat surface formed at a substantially middle portion inward in the longitudinal direction.
An adjustment knob storage hole 31B, which opens upward from the locking step 31A, can receive the shaft 33 of the adjustment knob 32, and has a locking piece 31D formed by a plurality of slit grooves 31C. The side 3 of the shaft portion 33, which is formed at the upper end 31E of the notch portion 31D and whose inner surface 31F has a polygonal shape.
An adjusting shaft insertion hole 31H that opens downward from the locking protrusion 31G that abuts 3C and the locking step 31A, and allows the adjustment shaft 29 of the starting valve 28 to pass therethrough, and the longitudinal direction of the adjustment shaft insertion hole 31H. Is formed at the lower end of the adjustment shaft insertion hole 31H and a positioning slide rod control groove 31J that prevents the rotational movement of the positioning slide rod 30 and allows movement in the longitudinal direction. A locking projection 31K having a diameter smaller than the outer diameter of the stopping projection 29B is formed.
End surface 33A of shaft portion 33 of adjustment knob 32 screwed to A
Is arranged in contact with the locking stepped portion 31A of the holder member 31, and the outer shape of the shaft portion 33 is arranged in contact with the locking projection 31G of the holder member 31, and the positioning slide rod 30 is arranged in the holder member 31. It is arranged in the positioning slide rod control groove 31J so as to be movable in the longitudinal direction, and one end is locked to the holder member 31 and the other end is fitted to the valve part 28A on the outer periphery of the locking projection 29B provided on the adjustment shaft 29. Spring 3 locked to
5. A sliding throttle valve type carburetor characterized in that 5 is contracted.