JPH01178758A - Starter for carburetor - Google Patents

Abstract

PURPOSE:To make a rich mixture suitable for a start-up feedable in abundance at the time of engine starting by installing a starting fuel pump room and also such a mechanism that opens a throttle valve as longer as the specified opening than that of idling. CONSTITUTION:A starting fuel pump room 7 is installed adjacently in a float chamber 4 of a carburetor body 1. After pulling an operating lever 40 to the left prior to starting operation on an engine, if this pulling operation force is released, this operating lever 40 moves to the right by dint of a spring 23 and comes to a stop at an intermediate position. A valve groove 43 of a pressure selector valve 42 installed in the operating lever 40 corresponds to an atmospheric inlet passage 44, whereby atmospheric air is led into an atmospheric chamber 37 of a diaphragm 35. Consequently, the diaphragm 35 and the operating lever 38 both move upward by dint of a first idle spring 39, turning a throttle valve lever 31 clockwise, and they hold a throttle valve 5 after making it open as longer as the specified opening than that of idling.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a carburetor that controls the concentration and amount of a mixture supplied to an engine, and particularly relates to a carburetor that supplies a rich mixture when starting an engine. The invention relates to a starting device.

[Prior Art] A starting device for a carburetor for a two-stroke engine, which has been commonly used in the past, will be explained with reference to FIG.

In (2), an intake passage 2 passes through the interior, a float basic body 3 is arranged on the side of the carburetor main body 1, and a float chamber 4 is formed by the lower four parts of the carburetor main body 1 and the float basic body 3. Ru.

A constant liquid level XX is formed within the float chamber 4 by a float, float pulp, and a valve seat (not shown).

Further, 5 is a throttle valve that opens and closes the intake passage 2.

Reference numeral 6 denotes a partitioning body such as a diaphragm that is separated from the float chamber 4 and divides the inside into a starting fuel pump chamber 7 and an atmospheric chamber 8. Specifically, the starting fuel pump chamber 7 is divided into the partitioning body 6 and the float basic body. 3, the atmospheric chamber 8 is formed by the four parts of the partition body 6
and cover 9. Note that J is an air hole that communicates the air chamber 8 with the atmosphere.

The following passages are opened in this starting fuel pump chamber 7. That is, 10 is a starting fuel inflow path which is provided with a suction side check valve 11 inside and communicates with the lower constant liquid level of the float chamber 4. A suction valve seat 12 is formed, and the suction side check valve 11 is pressed against the suction valve seat 12 by a spring 13.

Reference numeral 14 denotes a starting fuel discharge passage whose one end opens approximately in the center of the starting fuel pump chamber 7 and the other end opens into the intake passage 2 on the engine side (left side in the figure) from the throttle valve 5; In the passage, there is a discharge valve seat 15 and a spring 16 on the discharge valve seat 15.
A discharge side check valve 17 that is closed by being pressed is disposed.

Further, a valve seat 18 is formed at the opening end of the starting fuel discharge passage to the starting fuel pump chamber 7 .

Further, 19 is an on-off valve part provided integrally with the partition body 6,
This opening/closing valve section 18 is located at the valve seat 1 at the end of the starting fuel discharge passage 14.
The valve seat 18 is opened and closed in accordance with the movement of the partition body 6, thereby controlling the opening and closing of the starting fuel discharge passage 14. Further, an operating rod 20 is integrally disposed on the partitioning body 6, and by moving this operating rod 20, the partitioning body 6 and the on-off valve portion 18 are moved synchronously.

N is the first state pg (the state shown in Fig. 1) in which the operating rod 20 (including the compartment body 6 and on-off valve part 19) is fully pushed toward the starting fuel pump chamber 7 side, and the first state pg (the state shown in Fig. 1) is pushed fully toward the atmospheric chamber 8 side. The second pulled to
This is an intermediate position regulating member for holding the lever at an approximately midway point between the state (pulled all the way to the left in the figure), and specifically, a groove 20A is bored in the operating rod 20, and a groove 20A is formed in the operating rod 20, and the lever is moved to an intermediate position of the operating rod 20. It consists of a pawl 21 and a spring 22 that apply a pressing force perpendicularly to the operating rod 20 with elastic force to the groove 2OA during operation.

Further, 23 is contracted in the atmospheric chamber 8 and has one end attached to the cover 9.
It is a spring whose other end is locked to the partition body 6 and presses the partition body 6 toward the starting fuel pump chamber 7 side.

In addition, when operating the intermediate position regulating member N described above, the ball 21 is moved by the spring 22 into the groove of the operating rod 20 ・20A
The pressing force acting perpendicularly to the longitudinal axis Y-Y of the operating rod 20 is the pressing force acting perpendicularly to the longitudinal axis Y-Y of the operating rod 20 when the spring 23 is in the intermediate position state of the operating rod 20.
This is greater than the pressing force against the handlebar, and this allows the operating rod 20 to be held at the intermediate position.

Regarding starting the engine when the ambient temperature is low, first, before starting the engine, first press the operating lever 2.
0 to the left in the figure against the spring force of the spring 23. By this operation, the partition body 6 and the opening/closing valve part 19 also move to the left in synchronization with the operating rod 2o, and the opening/closing The valve portion 19 opens the valve seat 18 and increases the volume of the starting fuel pump chamber 7.

According to this, the suction side check valve 11 opens the suction valve seat 12, and the discharge side check valve 11-valve 17 closes the discharge valve seat 15.

Therefore, by such an operation, the fuel stored in the float chamber 4 is sucked into the starting fuel pump chamber 7.

Next, the small operation force to the left on the operating rod 20 is released, and according to this, the operating rod 20 is automatically moved toward the starting fuel pump chamber 7 side (to the right) in the figure by the spring force of the spring 23. It moves, and the operating rod 20 is in the groove 2.
The OA is stopped in a state where it is engaged with the ball 21 as the intermediate position regulating member N.

The fact that the operating rod 20 stops at the intermediate position and moves upward increases the pressing force of the spring 22 of the ball 21 acting in a direction perpendicular to the pushing force of the spring 23 in the longitudinal axis direction Y-Y of the operating rod 2o. This can be achieved by

When the operating rod 20 is moved to the intermediate position, the starting fuel pump chamber 7 is compressed and the chamber volume is reduced, so that the discharge side check valve 17 opens the discharge valve seat 15 and the starting fuel discharge passage 14 is opened. The starting fuel is injected and supplied into the intake passage 2, thereby preparing the engine for the first and complete explosion. Then, the process of pulling the operating rod 34 to the left all at once, and the operation to return it to the intermediate position. After going through the return process to release the attractive force on the rod, cranking operation for starting the engine begins.

Then, since the fuel in the starting fuel pump chamber 7 has already been injected into the intake pipe from the starting fuel discharge passage 14,
A sufficiently rich air-fuel mixture can be supplied to the engine, ensuring the initial and complete explosion of the engine.

When the engine enters a warm-up state after a complete explosion, the operating rod 20 is held at an intermediate position and the valve seat 18 is held open by the on-off valve part 19, so that the engine is not generated in the intake pipe. Negative pressure acts on the discharge side check jt17 from the starting fuel discharge passage 14, and the discharge side check valve 1 resists the spring force of the line 1 non-g.
7 is opened from the discharge valve seat 15, and fuel in the starting fuel pump chamber 7 is supplied from the starting fuel discharge passage 14 to the intake passage 2 to satisfy warm-up operation.

Next, when the warm-up of the engine is completed, the operating rod 20 is returned from the intermediate position to the original position shown in FIG. According to this, since the on-off valve section 18 closes the valve seat 18,
There is no possibility that fuel will flow out from inside the starting fuel pump chamber 7 to the starting fuel discharge passage 14.

[Problems to be Solved by the Invention] According to the conventional starting device, it was possible to increase the amount of starting fuel, but the i? ? Since it is not possible to measure MT4', the starting test to determine the starting performance takes time and the development efficiency is poor.

[Means for solving the problems] In view of the above-mentioned problems, the carburetor starting device according to the present invention has the following features:
The object of the present invention is to provide a device with good startability, which allows easy setting work for improving startability, and can supply the optimum starting fuel for initial explosion, complete explosion, and warm-up operation of the engine.
In order to achieve this purpose, the interior is divided into a starting fuel pump chamber and an atmospheric chamber by a partition body, and a suction side check valve is placed inside the starting fuel pump chamber to keep the fluid level below a certain level in the float chamber. A starting fuel inflow passage connected to the starting fuel pump chamber and a starting fuel discharge passage having a valve disposed therein on the discharge side are opened, and the compartment body is further pressed toward the starting fuel pump chamber side by a spring. An on-off valve section that can control the opening and closing of the fuel discharge passage, and an operating rod that obtains a pump operating force of 4t'j-L on the partition body are integrally provided, and the operation rod has an on-off valve section that can control the opening and closing of the fuel discharge passage. An intermediate position regulating member N is provided which can hold the partition body at an approximately intermediate position between a first state in which the starting fuel discharge passage is blocked and a second state in which the partition body is pulled toward the atmospheric chamber, and the gravitational force on the operating rod is reduced from the second state. When released, the partition body is automatically returned to approximately the intermediate position by the spring force, and the fuel in the starting fuel pump chamber is discharged through the starting fuel discharge passage, thereby reducing the atmospheric chamber and pressure. a diaphragm that is divided into a pressure chamber; an operating rod that is formed integrally with the diaphragm and is disposed corresponding to a throttle valve lever that penetrates through the atmospheric chamber and rotates synchronously with the throttle valve; When the pressure in the pressure chamber is at atmospheric pressure, it overcomes the force of the throttle valve return spring against the throttle valve lever in the direction of closing the throttle valve, presses the operating rod against the throttle valve lever, and opens the throttle valve at a constant opening compared to the idling opening. a first idle spring for opening, and a throttle valve actuating device;
In this state, the pressure chamber is connected to the intake passage on the engine side through the throttle valve of the carburetor, and on the other hand, from the state where the partition body is fully pulled toward the atmospheric chamber side, the intermediate position regulating member is used to connect the pressure chamber to the starting fuel pump chamber side. When the partition body returns to the approximately intermediate position, the fuel pump is started by the intermediate position regulating member, which has a pressure switching valve that connects the pressure chamber with the atmosphere, and when the partition body is fully pulled toward the atmospheric chamber side. This is a starting device for a carburetor that uses a throttle valve operating device to open the throttle valve to a certain opening compared to the idling opening when the partition body is returned to a substantially intermediate position toward the room.

[According to this, when the gravitational force on the operating rod is released from the first state where the operating rod is pulled all the way toward the atmospheric chamber, the operating rod automatically returns to the intermediate position due to the spring force.According to this, the starting fuel pump The starting fuel in the room is injected and supplied into the intake passage through the starting fuel discharge passage.

On the other hand, at the intermediate position of the operating rod, atmospheric pressure is introduced into the pressure chamber of the throttle valve actuating device by the pressure switching valve, so that the spring placed in the pressure chamber is throttled by the operating rod. The valve is rotated to open the throttle valve to a fixed opening compared to the idling opening.

Therefore, it is possible to supply the engine with a rich air-fuel mixture suitable for starting and an increased amount of air.

[Example] Hereinafter, the starting device for a carburetor of the present invention will be explained with reference to FIGS. 2, 3, 4, and 5.

Components having the same structure as those in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted.

A throttle valve shaft 30 is rotatably supported by the carburetor main body 1 and has a throttle valve 5 attached thereto.A throttle valve lever 31 is attached to an end of the throttle valve shaft 30.

The throttle valve lever 31 is provided with a first bent portion 31A and a second bent portion 31B, and a biasing force in the closing direction of the throttle valve 5 is applied by a throttle valve return spring 32.

A screw 33 for adjusting the minimum opening degree of the throttle valve 5 is screwed onto the carburetor body 1 in correspondence with the first bent portion 31A of the throttle valve lever 31.

Reference numeral 34 denotes a throttle valve operating device, the interior of which is divided into an atmospheric chamber 36 and a pressure chamber 37 by a diaphragm 35.

An operating rod 38 is integrally attached to the diaphragm 35,
This operating rod 38 passes through the atmospheric chamber 3B and the throttle valve lever 3
This corresponds to the second bent portion 31B of No. 1.

Also, a first idle spring 38 is compressed in the pressure chamber 37 to press the diaphragm 35 toward the atmospheric chamber 36.
The opening force of the throttle valve 5 to the throttle valve 8-31 via the operating rod 38 is the opening force of the throttle valve return spring 32 to the throttle valve lever 31 in the low opening range of the throttle valve 5. It is larger than power.

Further, reference numeral 40 denotes an operating rod that is integrally attached to the partition body 6, and this operating rod 40 is slidably moved within an operating rod guide hole 41 formed in the cover 9.

Further, 40A is a groove provided in the operating rod 40, and the intermediate position regulating member N is constituted by this groove 40A, the pawl 21, and the spring 22.

Reference numeral 42 denotes a pressure switching valve, which has the following configuration.

That is, 43 is a valve groove provided in the operating rod 40 disposed in the operating rod guide hole 41, and is formed by a groove portion having a smaller diameter than the outer diameter of the operating rod 40 in this example.

The outer periphery of the operating rod 40 on both sides of the valve groove 43 is fitted into the operating rod guide hole 41 and has a valve closing function.

In addition, the operating rod guide hole 41 includes a linear atmosphere introduction path 44 in which a negative end 44A is connected to the atmosphere and the other end 44B is connected to the pressure chamber 37, and a negative end 45A. A linear pressure introduction passage 45 is connected to the intake passage 2 on the engine side from the throttle valve 5, and the other end 45B is connected to the pressure chamber 37. The pressure introduction path 45 is perpendicular to and substantially parallel to the longitudinal direction Y-Y of the operating rod 40.

Then, the pressure switching valve 42 opens and closes when the partition body 6 is pressed toward the starting fuel pump chamber 7 side (in the state 7+21 in which the r section 19 closes the valve seat 18, the pressure switching valve 42
The pressure chamber 37 is connected to the pressure introduction path 45 by the groove 43 and is cut off from the atmosphere introduction path 44.
013 is released and the dividing body 6 is returned to approximately the intermediate position by the intermediate position regulating member N by the returning force of the spring 23.
As a result, the pressure chamber 37 is communicated with the atmosphere introduction path 44 and is cut off from the pressure introduction path 45.

Next, its effect will be explained.

First, a case where the engine atmosphere temperature and the engine temperature are high will be explained. Since the temperature is high, there is no need to supply a rich air-fuel mixture to the engine.

The actuating lever 40 of the starting device is therefore kept inactive. This state is shown in FIG. 2, where the partition 6 is pressed toward the starting fuel pump chamber 7 by the spring 23, and the on-off valve 18 provided integrally with the partition 6 discharges the starting fuel. Since the valve seat 18 opening into the starting fuel pump chamber in the passage 14 is kept closed, starting fuel is not discharged. Also, in such a state, the valve groove 43 of the pressure switching valve 42 opens the pressure introduction passage 45, while the atmosphere introduction passage 44
is blocked by the outer periphery of the operating rod 40 and the inner periphery of the operating rod guide hole 41. Therefore, the pressure chamber 3 of the throttle valve actuating device 34
7 is connected to the intake passage 2 on the engine side from the throttle valve 5 via the pressure introduction passage 45.

The opening state of the throttle valve 5 of the carburetor before the engine starts is such that the pressure chamber 37 is maintained at atmospheric pressure since the engine has not yet started and no negative pressure is generated in the intake passage 2. , the operating rod 3 is operated by the spring force of the first idle spring 39.
8 is in the upper position in the figure, and the throttle valve 5 is kept open to a certain degree from the idling degree.

When the engine is started in such a state, the starting fuel is not supplied from the starting fuel pump chamber 7 into the intake passage 2, so the starting air-fuel mixture is not made too rich, and the amount of air is increased. With good fuel atomization, the engine can be started with the rotational speed 4-4 degrees higher than the idling opening, thereby improving startability.

Then, when the engine goes through the initial explosion and complete explosion and returns to the normal operating state, the intake passage negative pressure generated in the intake passage 2 is introduced into the pressure chamber 37 of the throttle valve actuating device 34 through the pressure introduction passage 45. The diaphragm 35 is moved toward the pressure chamber 37 against the spring force of the first idle spring 38.

According to this, since the clockwise rotational pressing force of the operating rod 38 against the throttle valve lever 31 is released, the throttle valve lever 3] is rotated counterclockwise until it comes into contact with the screw 33 by the spring force of the throttle valve return spring 32. The desired idle link opening degree of the throttle valve 5 can be obtained by rotating the throttle valve 5 to the desired idle link opening degree.

Therefore, it is possible to immediately return to idling rotation without impairing fuel economy or producing noise.

Next, regarding starting the engine in a state where the ambient temperature is low, before starting the engine, first pull the operating rod 40 all the way to the left in the figure against the spring force of the spring 23. This is clearly shown in Figure 3. By this operation, the partition body 6 and the on-off valve section 18 are also moved to the left in synchronization with the operating rod 40, and the on-off valve section 18 is moved toward the valve seat 18.
At the same time, the volume of the starting fuel pump chamber 7 is increased.

According to this, the suction side check valve 11 opens the suction valve seat 12, and the discharge side check valve 17 closes the discharge valve seat 15.

Therefore, by such an operation, the fuel stored in the float chamber 4 is sucked into the starting fuel pump chamber 7.

Next, the leftward cutting force on the operating rod 40 is released. According to this, the operating rod 40 is automatically moved toward the starting fuel pump chamber 7 (to the right) in the figure by the spring force of the spring 23. The operating rod 40 is moved by the groove 4.
0A is stopped in a state where it is engaged with the ball 21 as the intermediate position regulating member N. (This state is shown in FIG. 4.

) Stopping the operating rod 40 at the intermediate position appropriately strengthens the pressing force of the spring 22 of the ball 21 acting in a direction perpendicular to the pressing force of the spring 23 in the longitudinal axis direction Y-Y of the operating rod 40. This can be achieved by

When the operating rod 40 is moved to the intermediate position, the starting fuel pump chamber 7 is compressed and the chamber volume can be reduced completely, so that the discharge side check valve 17 opens the discharge valve seat 15 and the starting fuel discharge passage 14 is opened. The starting fuel corresponding to the stroke of the partition body 6 is injected and supplied into the intake passage 2 .

On the other hand, in the pressure switching valve 42, the valve groove 43 is arranged corresponding to the atmosphere introduction passage 44, so that the atmosphere is introduced into the atmospheric chamber 37 via the atmosphere introduction passage 44.

According to this, the diaphragm 35 and the operating rod 38 move upward in the figure due to the spring force of the first idle spring 38, rotate the throttle valve lever 31 clockwise, and open the throttle valve 5 to a constant opening from the idling opening. and hold it.

After the process of pulling the operating rod 40 to the left all at once, and the return process of releasing the attractive force on the operating rod 40 to return it to the intermediate position, a cranking operation for starting the engine begins. Then, the fuel in the starting fuel pump chamber 7 is already injected into the intake pipe from the starting fuel discharge passage 14, and the throttle valve 5 is opened more than the idling opening, so a sufficiently rich mixture is supplied to the engine. It can be supplied in large quantities and ensures the initial and complete explosion of the engine.

When the engine enters a warm-up state after a complete explosion, the operating rod 40 is held at an intermediate position and the valve seat 18 is held open by the opening/closing valve part 19, so that the engine is not generated in the intake pipe. Negative pressure acts on the discharge side check valve 17 from the starting fuel discharge passage 14, opens the discharge side check valve 17 from the discharge valve seat 15 against the spring force of the spring 16, and the fuel in the starting fuel pump chamber 7 is opened. The starting fuel is supplied from the starting fuel discharge passage 14 to the intake passage 2, and an increased amount of air is supplied to the engine to satisfy warm-up operation.

In particular, since the rotational speed during the warm-up operation can be increased, the warm-up time can be shortened.

Then, once the warm-up of the engine is completed, the operating lever 40 is returned from the intermediate position shown in FIG. 4 to the original position shown in FIG. 2. According to this, since the opening/closing valve portion 18 closes the valve seat 18, the starting fuel discharge passage 14 is discharged from the starting fuel pump chamber 7.
No fuel will leak to.

On the other hand, in this state, the valve groove 43 of the pressure switching valve 42
Since the pressure introduction path 45 is kept open, the pressure chamber 37
The intake passage negative pressure of the intake passage 2 is introduced into the intake passage 2 through the pressure introduction passage 45. According to this, the diaphragm 35 moves downward in the figure against the spring force of the first idle spring 38, thereby eliminating the clockwise rotational force exerted by the operating rod 38 on the throttle valve lever 31 (2).

Therefore, the throttle valve lever 31 is connected to the throttle valve return spring 3.
The first bent part 3 of the throttle valve lever 31 due to the spring force of 2
The idling opening of the throttle valve 5 can be maintained by rotating counterclockwise until 1A contacts the screw 33.

During subsequent operation, the operating rod 38 will be connected to the throttle valve lever 31.
Since no rotational force is applied to the throttle valve 5, the idling opening degree of the throttle valve 5 set by the screw 33 can be maintained.

The operations of the diaphragm 35 and the operating rod 38 described above can be easily performed by selecting the negative pressure generated in the intake passage 2, the spring force of the fast idle spring 38 and the throttle valve return spring 32, or the pressure receiving diameter of the diaphragm 35. can be achieved.

Further, the pressure switching valve is not limited to the above-mentioned embodiment as long as it can operate the operation lever 4o described above and switch the passages of the air introduction passage and the pressure introduction passage with respect to the pressure chamber 37.

[Effects of the Invention] As described above, the carburetor starting device of the present invention has the following effects.

■When starting the engine at a low ambient temperature,
The desired starting fuel suitable for the engine's initial and complete explosion is directly injected into the intake duct from the starting fuel discharge passage without depending on the intake duct negative pressure (without relying on the starting fuel pump chamber), and the throttle valve is opened at idle. - By keeping the opening at a constant opening, a rich air-fuel mixture suitable for starting the engine can be supplied to the engine, which improves engine startability. This makes it possible to improve the efficiency of the starting performance test compared to a method that matches starting performance using only the air-fuel mixture.

- When the engine is warmed up, the throttle valve is kept open from the idling opening, so the engine rotational speed can be reduced to 2A, thereby shortening the warm-up time.

[Brief explanation of the drawing]

Figure 1 is a longitudinal sectional view showing a conventional carburetor starting device;
The figure is a longitudinal cross-sectional view showing a closed state of the starting fuel discharge passage of the starting device for a carburetor according to the present invention, and Fig. 3 is a longitudinal cross-sectional view showing a state in which the operating rod of Fig. 2 is pulled all at once on the atmospheric chamber side. 4 is a longitudinal sectional view showing a state in which the operating rod has been returned to an intermediate position from the state shown in FIG. 1... Carburetor body, 2... Intake path, 4...
...Floating chamber, 5.. Throttle valve, 6.. Compartment body, 7.. Starting fuel pump chamber, 8.. Atmospheric chamber, 9.
...Cover, XO...Starting fuel inlet passage, 14...Starting fuel discharge passage, 18...Valve seat, 1
9...Opening/closing valve part, 23...Sublink 3
1... Throttle valve lever, 32... Throttle valve return spring, 34...
Throttle valve operating device, 35... diaphragm, 36... atmospheric chamber,
37...pressure chamber, 3B...operation rod,
39...First idle spring, 40...
...Operation rod, 40A... Vortex, 42...
・Pressure switching valve, 44...Atmospheric introduction path, 45...
・Pressure introduction path,

Claims (2)

[Claims] (1) The interior is divided into a starting fuel pump chamber and an atmospheric chamber by a partition, and a suction side check valve is placed inside the starting fuel pump chamber, which is connected to a constant level below the liquid level in the float chamber. A starting fuel inflow passage and a starting fuel discharge passage in which a discharge side check valve is disposed are opened, and a partition body that is pressed toward the starting fuel pump chamber by a spring is provided with a starting fuel discharge passage that opens and closes. A controllable opening/closing valve part and an operating lever capable of applying a pump operating force to the partition body are integrally provided, and the operating lever includes:
An intermediate position regulating member N is provided which can hold the starting fuel discharge passage in a first state in which the opening/closing valve portion of the partition body is closed and a second state in which the partition body is pulled toward the atmospheric chamber. When the attractive force on the operating rod is released from the second state, the partition body is automatically returned to the approximately intermediate position by the spring force, and the fuel in the starting fuel pump chamber is discharged through the starting fuel discharge passage to start the carburetor. The device includes a diaphragm that divides into an atmospheric chamber and a pressure chamber, and an operating rod that is formed integrally with the diaphragm and is disposed corresponding to a throttle valve lever that passes through the atmospheric chamber and rotates synchronously with the throttle valve. is compressed in the pressure chamber, and when the pressure in the pressure chamber is at atmospheric pressure, it overcomes the force of the throttle valve return spring against the throttle valve lever in the direction of closing the throttle valve, presses the operating rod against the throttle valve lever, and closes the throttle valve. A first idle spring that opens to a constant opening from the idling opening; and a throttle valve actuating device consisting of;
In this state, the pressure chamber is connected to the intake passage on the engine side through the throttle valve of the carburetor, and on the other hand, from the state where the partition body is fully pulled toward the atmospheric chamber side, the intermediate position regulating member is used to connect the pressure chamber to the starting fuel pump chamber side. When the partition body returns to the intermediate position, it has a pressure switching valve that connects the pressure chamber with the atmosphere, and starts with the intermediate position regulating member from the state where the partition body is fully pulled toward the atmosphere chamber side. A starting device for a carburetor which operates a throttle valve actuating device to open a throttle valve to a certain opening compared to the idling opening when the partition body is returned to a substantially intermediate position. (2) the pressure switching valve is opened in a valve groove formed on the outer periphery of an operating rod that slides in an operating rod guide hole formed in the cover, and in an operating rod guide hole formed in the cover; The patent claim is formed by an atmosphere introduction passage that is perforated substantially parallel to the longitudinal axis of the operating rod and communicates with the atmosphere, and a pressure introduction passage that communicates with the intake passage on the engine side from the throttle valve. A starting device for a carburetor according to scope 1.