JPH1162706A - Caburetor with starting mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize operation performance of an engine by providing a holding means to constrain the valve element of a shut-off valve in an open valve position, and making a structure of this holding means so as to release constraint of the valve element by a valve lever when a throttle valve is opened to a certain opening degree. SOLUTION: If a linear movement part 31 is pulled with a knob against a spring 33 in advance of starting an engine, a valve element 28 is separated from a valve seat 27, and an air passage, a fuel passage part 23 and a mixed air passage part 24 composing an auxiliary passage 21 are connected in series. At this time, a constraining part 38 is moved in a direction to be released from a cut-out groove 37, and is fitted in an engagement groove 36 by a constraining spring 39 when the valve element 28 reaches a fully opened position, so that the linear movement part 31 is constrained in an open valve position. If cranking is carried out under this condition, air and fuel are suctioned by a negative pressure of intake air through the auxiliary passage 21, and is introduced into an intake air passage 5. After that, when a throttle valve 4 is opened wider than a partially opened position, constraint of the linear movement part 31 is released, and the valve element 28 is closed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carburetor installed in an intake line for supplying fuel to an engine, and more particularly to a carburetor for starting, warming up, and accelerating a cold engine. The present invention relates to a carburetor having a starting mechanism.

[0002]

2. Description of the Related Art An auxiliary passage is connected to a downstream side of a throttle valve of an intake passage having a venturi and a throttle valve for supplying a required amount of air-fuel mixture required by an engine, and the auxiliary passage is connected to the auxiliary passage when the engine is cold. It is widely known to supply an air-fuel mixture to enhance startability.

The starting mechanism including the above-mentioned auxiliary passage is provided with an air passage extending from the air intake, a fuel passage extending from the floating or diaphragm type constant fuel chamber, and a junction thereof to a downstream side of the throttle valve in the intake passage. An auxiliary passage comprising an air-fuel mixture passage extending toward the air passage, and an on-off valve for opening and closing the auxiliary passage to simultaneously shut off supply of air and fuel are provided.

In a carburetor for an automobile engine, the on-off valve is operated by a signal instructed by a microcomputer in accordance with the operating state of the engine, as described in, for example, Japanese Utility Model Laid-Open Publication No. 54-87320. Many are electromagnetically driven.

On the other hand, in a carburetor for a general-purpose engine, the on-off valve is normally opened and closed manually. The throttle valve lever is held in an open position by engaging the throttle valve, and the throttle valve starts to open, a normal air-fuel mixture is supplied from the intake passage, and at the same time, the engagement is released and the valve is closed. Kaihei 8-284
No. 754.

[0006] A carburetor for a general-purpose engine is required to be small and inexpensive, and the opening and closing valve of the auxiliary passage is manually opened and the throttle valve lever is engaged to hold or release the valve in the open position. The starting mechanism described in JP-A-8-284754, in which the valve is closed by a spring force, can meet this demand.

[0007]

However, when the throttle valve starts to open from the idle position, the opening / closing valve operates from the fully open state to the fully closed state. Open the auxiliary passage only when starting and warming-up.

For this reason, when the throttle valve starts to open, there is a concern that the air-fuel ratio and the amount of intake air may fluctuate temporarily, resulting in malfunction of the engine. In addition, there is a concern that if the throttle valve is opened at a time when the warm-up is insufficient, the engine may be stopped due to a shortage of fuel.

According to the present invention, according to the starting mechanism provided in the carburetor for a general-purpose engine, the air-fuel mixture is supplied from the auxiliary passage only when the throttle valve is at the idle position. When the opening of the engine begins to open, the engine engine malfunctions or there is a concern that the engine may be stopped due to insufficient warm-up. The present invention has been devised to provide a starting mechanism capable of supplying an air-fuel mixture and operating the engine stably.

[0010]

SUMMARY OF THE INVENTION The present invention provides an air passage extending from an air intake, a fuel passage extending from a constant fuel chamber, and a mixture passage extending from a junction thereof and connected downstream of a throttle valve of an intake passage. And an auxiliary passage having a valve body that is manually moved in the valve opening direction and a spring member that urges the valve body in the valve closing direction. The auxiliary passage is opened and closed to simultaneously shut off supply of air and fuel. In order to solve the above-mentioned problems of the carburetor provided with a starting mechanism having an on-off valve, the following is made.

That is, a holding means for restraining the valve element of the on-off valve at the valve opening position is provided, and this holding means releases the restriction of the valve element by the throttle valve lever when the throttle valve is opened to a certain opening. It is configured. With this configuration, when the throttle valve is between the idle position and a certain opening position, the air-fuel mixture is supplied from the auxiliary passage, and not only the start and the warm-up operation of the cold engine are surely performed, but also, Acceleration operation in this state can also be performed, and the auxiliary passage is closed when the throttle valve is opened considerably, so that the operation can be smoothly switched to only the normal mixture from the intake passage. Became.

The valve body of the on-off valve may be moved linearly without rotation, or may be moved linearly while rotating. In the former, the holding means for restraining the linearly moving portion including the valve body at the valve opening position preferably comprises an engaging groove of the linearly moving portion and a restraining member which fits into and disengages from the engaging groove. . In the case of the latter, a locking surface provided on the top of a cam formed opposite to the linearly moving portion and the carburetor body portion, or an engaging step provided on the linearly moving portion and the throttle valve lever It is preferable to use a projection or the like. These are operated by a throttle valve lever so that the restricting member escapes from the engagement groove at a certain opening degree of the throttle valve or more, and the linearly moving portion is rotated in the restriction releasing direction.

Further, in the case where the valve body moves linearly while rotating, the throttle valve may be slightly opened from the idle position by pressing the throttle valve lever when restrained at the valve opening position. This allows an engine that requires a large amount of air at low speed to send air from both the auxiliary passage and the intake passage to perform a stable operation.

[0014]

1, 2, 3, 4, and 5 show an embodiment of the invention described in claims 1 and 2, which have a choke valve 2, a venturi 3, and a throttle valve 4. A fuel pump 6 and a constant fuel chamber 10 are provided on the outer surface of the carburetor body 1 with the intake passage 5 interposed therebetween.

In the fuel pump 6, a pump diaphragm 7 and a pump cover body 8 are sequentially stacked on one side of the carburetor body 1, and a recess is provided in the carburetor body 1 and the pump cover body 8 with the pump diaphragm 7 interposed therebetween. Is used as a fuel pump chamber and a pulse pressure chamber, and the pulse pressure generated in the crankcase of the engine is introduced into the pulse pressure chamber to operate the pump diaphragm 7, thereby sucking the fuel in the fuel tank into the fuel pump chamber. This is a well-known configuration in which the fuel is discharged to the constant fuel chamber 10 through the fuel passage, and the fuel pump chamber, the pulse pressure chamber, and the fuel passage are not illustrated.

The constant fuel chamber 10 is formed by a recess provided on another side of the carburetor body 1, and a diaphragm cover 12 is formed by a diaphragm 11 superposed on this side.
Is partitioned from the atmosphere chamber 13 formed on the inner surface of. A fuel valve (not shown) opens and closes a fuel passage in accordance with the displacement of the diaphragm 11 to cause the constant fuel chamber 10 to hold fuel regulated at a constant pressure, as is well known in the art.

The fuel in the constant fuel chamber 10 is drawn through the main fuel passage 14 from the main nozzle 15 opened at the narrowest portion of the venturi 3 into the intake passage 5, or passes through the low speed fuel passage 16 to the side of the throttle valve 4. The air is sucked into the intake passage 5 from the idle port 17 and the slow port 18 which are opened to the front. The main fuel passage 14 and the low-speed fuel passage 16 are usually provided with a manual adjustment valve (not shown) so that the fuel flow rate can be adjusted.

Next, the auxiliary passage 21 constituting the starting mechanism of the present invention has an air intake 22a opened to the intake passage 5 on the upstream side of the choke valve 2 so that the side of the intake passage 5 is parallel to this. An air passage portion 22 extending from the constant fuel chamber 10 to a side of the intake passage 5 at right angles to the fuel passage portion 23;
And an air-fuel mixture passage portion 24 extending parallel to the side of the intake passage 5 from the junction of the two passage portions 22 and 23 and opening to the intake passage 5 downstream of the throttle valve 4. . In a carburetor without the choke valve 2, the air intake 22 a is opened to the intake passage 5 at a suitable position on the upstream side of the venturi 3.

The air passage portion 22 and the mixture passage portion 24 are arranged on the same center line, and a cylinder chamber-shaped valve chamber 26 is provided between them at right angles to the center line. A valve seat 27 having a through hole 27a as a measuring jet is installed at the bottom of the valve chamber 26, and the fuel passage portion 23 communicates with the valve chamber 26 through the through hole 27a.

A cylindrical guide member 34 is fitted and fixed to an end of the valve chamber 26 which is open to the side surface of the carburetor body 1, and a plunger-shaped valve body 28 is inserted from the valve chamber 26 into the inner hole of the guide member 34. It is movably fitted over 34a. The valve body 28 functions to close the fuel passage portion 23 when seated on the valve seat 27 and at the same time to close the air passage portion 22 and the mixture passage portion 24, particularly, the air passage portion 22.

The end surface of the valve body 28 opposite to the seating surface on the valve seat 27 is formed as a conical inclined step portion 28a, and a knob 3 is formed on a shaft end protruding from a guide member 34 of an operating shaft 29 extending therefrom.
0 is attached. The valve body 28, the operating shaft 29 and the knob 30 constitute a linearly moving portion 31. An annular engagement groove 36 is provided on the outer peripheral surface of the valve body 28, and the distal end wall of the guide member 34 A valve-closing spring member 33 made of a compression coil spring is inserted between a spring seat 32 fixed to the operation shaft 29.

The above-mentioned valve chamber 26, valve seat 27, valve body 28, operating shaft 29, knob 30, spring member 33, and guide member 34 constitute an on-off valve 25.

The guide member 34 has a U-shaped notch groove 37 into which a restraining member 38 is removably fitted. That is, the restraining member 38 has a U-shaped engaging portion 38 a fitted into the notch groove 37 and the spring receiving portion 3 extending from one end thereof.
8b, and a constraint spring 39 made of a compression coil spring is inserted between the guide member 34 and the spring receiving portion 38b.

The state shown in FIG. 2 and FIG.
Is seated on the valve seat 27 to close the auxiliary passage 21, the engagement portion 38 a of the restraining member 38 is in contact with the outer peripheral surface of the operation shaft 29.

Prior to the start of the engine, when the linearly moving portion 31 is pulled with the knob 30 against the spring force of the spring member 33, the valve body 28 separates from the valve seat 27 and the air passage portions 22,
The fuel passage 23 and the mixture passage 24 communicate with each other. The restraining member 38 is provided with the notch groove 37 along the inclined step portion 28a.
When the valve body 28 reaches the fully open position, the valve body 28 is fitted into the engagement groove 36 by the spring force of the restraining spring 39, and the state shown in FIGS. 4A and 4B is obtained. As a result, even when the hand is released from the knob 30, the linearly moving portion 31 is restricted to the valve opening position.

The engaging groove 36, the restraining member 38, and the restraining spring 39 constitute a holding means 35 for holding the valve body 28 of the on-off valve 25 at the valve opening position. The air and fuel are sucked from the air passage 22 and the fuel passage 23 by the intake negative pressure generated on the downstream side of the throttle valve 5 and merged and mixed in the valve chamber 26. 5 and supplied to the engine.

A throttle valve lever 43 is fixed to a shaft end of the throttle valve shaft 42 supporting the disk-shaped throttle valve 4 and protruding outward from the carburetor body 1. The throttle valve lever 43 rotates the throttle valve 4 from an idle position to a fully open position by a driver's accelerator operation, and a return spring formed of a torsion coil spring (not shown) rotates the throttle valve 4 from an open position to an idle position.

The throttle valve lever 43 has an arm piece 44. The arm piece 44 comes into contact with the spring receiving portion 38b of the restraining member 38 when the throttle valve 4 is opened from the idle position to a partially opened position, generally a partially opened position close to full open. For this reason, the air-fuel mixture required for starting and warming-up when the engine is cold can be supplied through the auxiliary passage 21 regardless of whether the throttle valve 4 is located at the idle position or at a certain open position. . Also, when the throttle valve 4 is suddenly opened while the engine is cold to perform the acceleration operation, the auxiliary passage 21 is opened as long as the throttle valve 4 is opened below the partial opening position. An air-fuel mixture can be supplied.

When the throttle valve 4 is opened more than the partial opening position, as shown in FIG.
8b to release the engagement portion 38a from the engagement groove 36,
As a result, the linear moving portion 31 released from the restraint becomes the spring member 3.
3 and is advanced until the valve body 28 is seated on the valve seat 27, and returns to the state of FIGS. 2 and 3 to close the auxiliary passage 21. Thereafter, the air-fuel mixture only through the intake passage 5 is supplied to the engine.

When the supply of the air-fuel mixture from the auxiliary passage 21 becomes unnecessary when the throttle valve 4 is at the idle position or the small opening position, the driver generally recognizes that the warm-up operation of the engine has been completed. In this case, pressing the knob 30 or pressing the spring receiving piece 38b causes the restraining member 38 to escape from the engagement groove 36 and close the auxiliary passage 21.

Next, FIGS. 6, 7 and 8 show an embodiment of the invention described in claims 1 and 3, wherein an air passage 22 of an auxiliary passage 21 and a mixture passage 24 are provided. A valve chamber 26 of an on-off valve 25 is provided at right angles to these center lines, and a valve seat 2 having a through hole 27a as a metering jet is provided at the bottom thereof.
7, the fuel passage 23 communicates with the valve chamber 26 through the through hole 27a.

A short cylindrical guide member 54 is fitted and fixed to an end of the valve chamber 26 which is open to the side surface of the carburetor body 1.
A piston-shaped valve body 28 fitted in the valve chamber 26 is provided with a valve seat 27.
Between the valve seat 27 and the distal end surface of the guide member 54.
When the seat is seated, the fuel passage 23 is closed and at the same time, the air passage 22 and the mixture passage 24, in particular, the air passage 2
2 is closed.

A valve shaft 56 extends through the guide member 54 on the opposite side of the seat surface of the valve body 28 to the valve seat 27. The shaft end of the valve shaft 56 projecting from the guide member 54 The starting lever 57 is fixed. A valve closing spring member 33 made of a compression coil spring is inserted between the valve seat 28 and the guide member 54 so as to surround the valve shaft 56.

The above-described valve chamber 26, valve seat 27, valve body 28, spring member 33, valve shaft 56, and starting lever 57 constitute a linearly moving portion 59 which linearly moves while rotating.

The guide member 54 is fixed to the carburetor body 1 to form a part thereof, and cams 55 and 58 each having an inclined surface are formed on the end faces of the guide member 54 and the starting lever 57 facing each other. Along with
The most protruding portions of these cams 55, 58, that is, the tops, are locking surfaces 55a, 58a perpendicular to the central axis.

The locking surfaces 55a, 5 of the above-described cams 55, 58
8a constitutes holding means 35 for holding the valve body 28 of the on-off valve 25 at the valve opening position.

Prior to starting the engine, FIG.
When the starting lever 57 placed at the valve closing position shown in (B) is manually rotated counterclockwise in the figure, the starting lever 57
The top of the cam 58 moves in the circumferential direction along the cam 55 of the guide member 54, so that the linearly moving portion 59 rotates and is pulled out of the carburetor body 1 against the spring force of the spring member 33. And when they are rotated 90 degrees, the locking surfaces 55a and 58a overlap with each other, resulting in the state shown in FIGS. 7A and 7B.

The valve body 28 is held at the valve-open position by the overlapping of the locking surfaces 55a and 58a, so that the air-fuel mixture necessary for starting the engine and warming up can be supplied through the auxiliary passage 21.

The starting lever 57 has an engagement step 57 on the outer periphery.
The throttle valve lever 43 fixed to the shaft end of the throttle valve shaft 42 has an arm piece 45.
The arm piece 44 hits the engagement step 57a when the throttle valve 4 is opened to a partially open position close to full open, and then pushes the starting lever 57 until the throttle valve 4 reaches the fully open position shown in FIG.
Rotate 8 clockwise. As a result, the locking surface 58a of the starting lever 57 is disengaged from the locking surface 55a of the guide member 54, and the unrestricted linear moving portion 59 is released from the spring member 33.
6A, the valve body 28 advances according to the inclination of the cam 55 until the valve body 28 is seated on the valve seat 27, and returns to the state of FIG. 6A to close the auxiliary passage 21.

The timing at which the on-off valve 25 starts closing is determined by the positional relationship between the engagement step 57a and the arm piece 45, the locking surface 55a,
It can be arbitrarily set according to the circumferential length of 58a, and it is possible to smoothly start, warm up, and accelerate the engine in a cold state by the mixture supplied from the auxiliary passage 21. .

It is to be noted that the rotation of the starter lever 57 by hand without using the throttle valve lever 43 allows
9, the auxiliary passage 21 can be closed at any time.

FIG. 9 shows an embodiment of the holding means 35 for holding the valve element of the on-off valve in the valve opening position, in particular, in the first and fourth aspects of the present invention. 8
A locking projection 61 provided on a starting lever 57 which is a part of the linearly moving portion 59 of the on-off valve 25 shown in FIG.
The holding means 35 is constituted by the locking step portion 62 provided in the above.

FIG. 9A shows one of the positional relationships between the starting lever 57 and the throttle valve lever 43 when the on-off valve 25 closes the auxiliary passage 21 and the engine is stopped or running. The starting lever 57 has the same phase as the starting lever 57 in the valve closing position shown in FIG.

When the cold start of the engine is started, when the start lever 57 is rotated by 90 degrees in the counterclockwise direction in the figure by hand, the linearly moving portion 59 is rotated by the cam and moved in the direction of being pulled out of the carburetor body to open. At the same time, the locking projection 61 engages with the locking step 62 of the throttle valve lever 43 at the idle position, and the state shown in FIG. 9B is obtained.
In this state, the start-up and warm-up operation are performed by the mixture supplied from the auxiliary passage.

When the throttle valve starts to be opened from the idle position, the throttle valve lever 43 rotates counterclockwise in the drawing, and the engagement depth between the locking projection 61 and the locking step 62 gradually decreases, and the starting lever 57 Is rotated clockwise in the figure, but is kept open by being restricted by the throttle valve lever 43.

When the throttle valve lever 43 further rotates in the throttle valve opening direction, the locking step 62 is disengaged from the locking projection 61, and the restraint shown in FIG. 9C is released. Thereafter, the opening and closing valve is brought to the valve closing position by the same operation as that shown in FIGS. 6 and 7 by the cam and the valve closing spring member.

By appropriately setting the engagement depth between the locking projection 61 and the locking step 62, the acceleration operation from the idle position can be performed with the auxiliary passage open.

In the embodiment shown in FIG. 9, the torsion spring is used in place of the compression coil spring for the valve-closing spring member, and the retaining surface of the cam used as the holding means 35 in the previous embodiment is eliminated. Accordingly, when the locking step 62 is disengaged from the locking projection 61, the linearly moving portion 59 immediately operates in the valve closing direction, and the release of the constraint is reliably performed.

FIG. 10 shows an embodiment different from that of FIG. 9 of the holding means 35 for holding the valve element of the on-off valve in the valve opening position in the first and fifth aspects of the present invention. Linear moving part 59 of the on-off valve 25 shown in FIGS.
Locking recess 64 provided in the starting lever 57 which is a part of
And the locking projection 65 provided on the throttle valve lever 43 constitute the holding means 35.

In the embodiment shown in FIG. 10, when the linearly moving portion 59 moves from the valve closing position to the valve opening position, the embodiment shown in FIGS. 6, 7, and 8 and the embodiment shown in FIG. The difference is that the above configuration rotates counterclockwise, whereas the configuration rotates clockwise.

FIG. 10A shows one of the positional relationships between the starting lever 57 and the throttle valve lever 43 when the on-off valve closes the auxiliary passage and the engine is stopped or running.

When starting a cold engine,
When the starting lever 57 is manually rotated clockwise by 90 degrees in the figure, the cam moves the linearly moving portion 59 in the direction in which it is withdrawn from the carburetor body and opens the valve. The starting lever 57 pushes the throttle valve lever 43 in the idle position at the end of the rotation to slightly open the throttle valve, and the locking recess 64 fits into the locking projection 65 of the throttle valve lever 43, as shown in FIG.
The state shown in FIG.

The throttle valve lever 43 is applied with a rotational force toward the idle position by a return spring that closes the throttle valve.
7 serves as a stopper for preventing the movement of the counterclockwise rotation of the counterclockwise direction 7. In this state, the mixture supplied from the normal intake passage with the throttle valve slightly opened is added to the mixture supplied from the auxiliary passage, and the engine is started and the warm-up operation is performed.

Since this embodiment supplies a larger amount of air-fuel mixture during idling than that provided only by the auxiliary passage, it is effective for an engine that requires a considerably large output even at a low speed, such as a blower engine. is there.

When the throttle valve is started to be opened from the starting position shown in FIG. 10B, the throttle valve lever 43 rotates counterclockwise in the drawing, and the engagement between the locking recess 64 and the locking projection 65 is achieved. Although the depth gradually decreases, the starting lever 57 is restrained by the throttle valve lever 43 and maintains the valve open state.

When the throttle valve lever 43 further rotates in the throttle valve opening direction, the locking projection 65 is disengaged from the locking recess 64, and the restraint shown in FIG. 10C is released. Thereafter, the opening and closing valve is brought to the closed position by the cam and the valve-closing spring member in the same operation as in the embodiment shown in FIGS. In addition, by appropriately setting the fitting depth between the locking recess 64 and the locking projection 65, the acceleration operation from the starting position can be performed with the auxiliary passage 21 kept open.

Also in the embodiment shown in FIG. 10, the spring member for closing the valve is a torsion spring, and the locking surface of the cam is eliminated so that the locking projection 65 is disengaged from the locking recess 64 when it is released. The release can be ensured.

[0058]

As described above, according to the present invention, the air-fuel mixture is supplied by the auxiliary passage provided separately from the regular intake passage until the throttle valve is opened from the idle position to a certain opening.
In particular, when the auxiliary passage is closed, the supply of the air-fuel mixture is properly switched, so that the engine can be operated stably.

In addition, according to the present invention, it is possible to perform an acceleration operation with the auxiliary passage open, and to measure an increase in the amount of air-fuel mixture at the time of starting, so that it is possible to meet various requirements of the engine.

[Brief description of the drawings]

FIG. 1 is a partially cutaway front view showing a first embodiment of the present invention.

FIG. 2 is a cross-sectional view taken along line XX of FIG.

FIG. 3 is an enlarged sectional view taken along line YY of FIG. 2;

4A and 4B show a state where an on-off valve according to the first embodiment is opened, and FIG. 4A is a cross-sectional view similar to FIG. 3, and FIG.
(A) is a partially cut front view of (A).

FIG. 5 is a front view similar to FIG. 4B, illustrating a state in which the holding unit in the first embodiment is released.

6A and 6B show a state in which an on-off valve according to a second embodiment of the present invention is closed, wherein FIG. 6A is a cross-sectional view and FIG. 6B is a partially cut-away front view.

7A and 7B show a state in which an on-off valve according to a second embodiment is opened, wherein FIG. 7A is a cross-sectional view and FIG. 7B is a front view.

FIG. 8 is a front view similar to FIG. 7B, illustrating a state in which a holding unit according to the second embodiment is released.

FIG. 9 is a front view illustrating a holding unit and its operation according to a third embodiment of the present invention.

FIG. 10 is a front view illustrating a holding unit and an operation thereof according to a fourth embodiment of the present invention.

[Explanation of symbols]

1 carburetor body, 4 throttle valve, 5 intake passage, 1
0 constant fuel chamber, 21 auxiliary passage, 22 air passage,
23 fuel passage, 24 mixture passage, 25
On-off valve, 28 valve element, 33 spring member, 35 holding means, 43 throttle valve lever,

Claims (5)

[Claims] 1. An auxiliary passage comprising an air passage extending from an air intake, a fuel passage extending from a constant fuel chamber, and a mixture passage extending from a junction thereof and connected to a throttle valve downstream of an intake passage. An opening / closing valve that has a valve body that is manually moved in the valve opening direction and a spring member that urges the valve body in the valve closing direction, and that opens and closes the auxiliary passage to simultaneously shut off supply of air and fuel. A carburetor having a starting mechanism; holding means for restraining the valve body in an open position, wherein the holding means restrains the valve body by a throttle valve lever when the throttle valve is opened to a certain opening. A vaporizer. 2. The valve body of the on-off valve is linearly moved, and the holding means is adapted to be fitted into and disengaged from an engaging groove provided on an outer peripheral surface of a linearly moving portion including the valve body. And a restricting member urged by a spring force in a fitting direction, wherein the throttle valve lever releases the restricting member from the engagement groove when the throttle valve has a certain opening degree or more, and restricts the linearly moving portion. A vaporizer having a starting mechanism according to claim 1, further comprising an arm piece for moving the arm in a direction in which the armature is released. 3. The valve body of the on-off valve is linearly moved with the rotation of the linearly moving part following a cam formed opposite to a linearly moving part including the valve body and a carburetor main body, and the holding means is An arm for rotating the throttle valve lever in a direction of releasing the constraint due to the overlapping of the locking surfaces of the linearly moving portion when the throttle valve has a certain opening degree or more; A carburetor having a starting mechanism according to claim 1 having a piece. 4. The valve body of the on-off valve is linearly moved with rotation of the linearly moving part following a cam formed opposite to a linearly moving part including the valve body and a carburetor main body, and the holding means is A locking projection provided on the linearly moving portion and a locking step provided on the throttle valve lever, wherein the throttle valve lever is provided with the locking projection of the locking step at a certain opening degree or more of the throttle valve. The carburetor provided with a starting mechanism according to claim 1, wherein the carburetor is configured to release a restriction due to engagement with the carburetor. 5. The valve body of the on-off valve is linearly moved with the rotation of the linearly moving part following a cam formed opposite to a linearly moving part including the valve body and a carburetor main body, and the holding means is The throttle valve lever comprises a locking recess provided on the linearly moving portion and a locking projection provided on the throttle valve lever. The throttle valve lever is configured to lock the throttle valve with the locking projection at a position slightly opened from an idle position. 2. A carburetor having a starting mechanism according to claim 1, wherein said valve body is restrained at a valve opening position by fitting a recess, and said restraint is released when said throttle valve has a certain opening degree or more.