JP4192432B2 - Vaporizer low speed fuel system - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a carburetor that adjusts and controls the amount and concentration of an air-fuel mixture supplied to an engine, and more particularly to a low-speed fuel device that controls fuel in the region of low-speed operation and intermediate opening operation of the engine.
[0002]
[Prior art]
A conventional carburetor low speed fuel system is shown in FIG. Reference numeral 1 denotes a carburetor main body through which an intake passage 2 passes. The intake passage 2 is controlled to be opened and closed by a throttle valve 4 attached to a throttle valve shaft 3 rotatably supported by the carburetor main body 1. 5 is a first low-speed air jet for controlling low-speed air, 6 is a low-speed fuel jet for controlling low-speed fuel, and the first low-speed air controlled by the first low-speed air jet 5 is the first low-speed air jet. Is supplied to the low-speed fuel jet 6 provided with the mixing pipe 6 </ b> A through the low-speed air passage 7. The air cut valve device A includes the following. Reference numeral 8 denotes a partition body made of a diaphragm disposed between the recess 1A of the vaporizer body 1 and the cover 9 covering the same, and a low-speed air chamber 10 is formed by one side surface of the partition body 8 and the recess 1A. A pressure receiving chamber 11 is formed by the other side surface of the body 7 and the cover 9. A negative pressure introduction path V opens in the pressure receiving chamber 11, and this negative pressure introduction path V opens from the throttle valve 4 to the engine side intake path 2 </ b> A (right side in FIG. 5). The low-speed air chamber 10 has an upstream second low-speed air passage 12 </ b> A and a valve body housing hole 13. The upstream side of the second low-speed air passage 12 </ b> A on the upstream side communicates with the atmosphere and opens, for example, on the upstream side of the intake passage 2. The valve body storage hole 13 has a constant diameter and is formed to open toward the bottom of the low-speed air chamber 10. A ring in which a guide hole 14 </ b> A is formed in the opening of the valve body storage hole 13. The bush 14 is fitted and arranged. A check valve 15 having an outer diameter smaller than the diameter of the valve body storage hole 13 is disposed in the valve body storage hole 13, and the outer periphery of the check valve 15 and the inner periphery of the valve body storage hole 13 are arranged. There is a gap between them. The flange member 8A formed integrally with the partition body 8 is disposed so as to face the check valve 15 through the inner guide hole 14A of the ring-shaped bush 14, and the check valve 15 is a check valve spring 16. Therefore, it is always urged to come into contact with the tip of the flange member 8A. Reference numeral 17 denotes a partition body spring that is contracted in the pressure receiving chamber 11 and presses the partition body 8 toward the low-speed air chamber 10. The spring force of the partition body spring 17 is stronger than the spring force of the check valve spring 16. According to this, the partition body 8 is biased toward the low-speed air chamber 10, and the check valve 15 also compresses the check valve spring 16 via the flange member 8A to bias rightward in FIG. Being held. The diameter of the guide hole 14 </ b> A is set smaller than the outer diameter of the check valve 15. A second low-speed air passage 12B on the downstream side that branches off from the first low-speed air passage 7 opens in the valve body housing hole 13, and the second low-speed air passage 12B on the downstream side has a second inside. A low speed air jet 18 is arranged. That is, the second low-speed air passage 12 is formed by the upstream second low-speed air passage 12A and the downstream second low-speed air passage 12B. Note that the gap formed between the guide hole 14A of the ring-shaped bush 14 and the flange member 8A and the gap formed between the outer periphery of the check valve 15 and the inner periphery of the valve body storage hole 13 are the second low-speed air. It is set to be sufficiently larger than the effective area of the jet 18.
[0003]
When the negative pressure generated in the intake passage 2 acting on the pressure receiving chamber 11 via the negative pressure introduction passage V is equal to or less than a predetermined value, the compartment 8 is on the low-speed air chamber 10 side by the spring force of the compartment spring 17. According to this, the control rod 8A presses and holds the check valve 15 to the right against the spring force of the check valve spring 16. According to the above, the second low-speed air passage 12A on the upstream side and the second low-speed air passage 12B on the downstream side are the low-speed air chamber 10, the gap between the guide hole 14A of the ring-shaped bush 14 and the flange member 8A, check This is communicated via a gap between the outer periphery of the valve 15 and the valve body housing hole 13. According to this, the first low-speed air controlled by the first low-speed air jet 5 and the first low-speed air jet 5 are directed toward the low-speed fuel jet 6. 2 The low-speed air that is summed with the second low-speed air controlled by the low-speed air jet 18 is supplied, whereby low-speed fuel (low-speed mixture) that satisfies the low-speed operation and the intermediate opening operation of the engine is supplied to the bypass hole 19. Etc. On the other hand, when the engine enters a sudden deceleration operation in which the engine is rapidly decelerated from the high opening operation, a very large negative pressure is generated in the intake passage 2A on the engine side from the throttle valve 4, and this large negative pressure is generated. Is introduced into the pressure receiving chamber 11 through the negative pressure introduction path V. When the negative pressure in the pressure receiving chamber 11 rises to a certain negative pressure value or more as described above, the partition body 8 including the flange member 8A is largely opposed to the spring force of the partition body spring 8 (in FIG. 5). According to this, the check valve 15 moves to the left synchronously with the flange member 8A by the spring force of the check valve spring 16, and the left end surface of the check valve 15 is the right end surface of the ring-shaped bush 14. The guide hole 14A is closed and held. According to the above, the second low-speed air flow flowing through the second low-speed air passage 12B on the downstream side is interrupted, and the amount of low-speed air flowing toward the low-speed fuel jet 6 is reduced to the second low-speed air jet 18 minutes. The low-speed gas mixture concentration can be increased. Therefore, the dilution of the air-fuel mixture during the rapid deceleration operation of the engine is suppressed, so that harmful exhaust gas components can be reduced and the operability of the engine can be improved.
[0004]
[Problems to be solved by the invention]
According to such a conventional low-speed fuel device for a carburetor, it is difficult to reduce the manufacturing cost. Specifically, the manufacturing cost of the air cut valve device cannot be reduced. The first cause is that it is necessary to prepare the check valve spring 16, the check valve 15, the ring-shaped bush 14, and the flange member 8A, and the increase in the number of parts hinders the reduction of the parts cost. The second cause lies in the assembly method. After the check valve spring 16 and the check valve 15 are arranged in the guide hole 14A, the ring-shaped bush 14 is fitted and arranged from the opening of the guide hole 14A. The operation of fitting and arranging the ring-shaped bush 14 to the check valve 15 in the backup state by the spring 16 is difficult. Further, since the saddle member 8A and the check valve 15 are formed separately, it is difficult to directly check the operation of the check valve 15 by confirming the operation of the outward saddle member 8A. is there.
[0005]
The low-speed fuel device for a carburetor according to the present invention has been made in view of the above problems, and provides the low-cost device by reducing the number of parts constituting the air cut valve device and improving the assembly workability. For the purpose.
[0006]
[Means for achieving the object]
In order to achieve the above object, the low speed fuel device for a carburetor according to the present invention provides a second low speed air having a second low speed air jet from a first low speed air passage from the first low speed air jet to the low speed fuel jet. A low-speed fuel for a carburetor provided with an air cut valve device for branching off the second low-speed air passage when the negative pressure in the intake passage rises above a certain value in the second low-speed air passage while branching the passage in the apparatus, the air cut valve device includes a low-speed air chamber second low speed air passage upstream of leading to the atmosphere is opened, to the pressure receiving chamber the negative pressure introduction path communicating with the intake passage downstream of the throttle valve is opened A partition body to be divided, a valve body guide hole that opens toward the low-speed air chamber, an annular groove portion in the valve body guide hole, having a diameter larger than the diameter of the valve body guide hole and having a groove width; End is annular Open to portion, the downstream end is contiguous to the first low-speed air passage, and a second low-speed air passage downstream of Ru with a second low-speed air jets inside, slidably disposed in the valve body guide hole And a valve body that is integrally attached to the partition body through the small-diameter portion, and that can open and close the opening into the valve body guide hole of the annular groove portion ,
When the negative pressure in the intake passage is below a certain value, the annular groove (21) is held open toward the valve body guide hole by the valve body (22), and the second low-speed air passage on the upstream side and the second downstream side on the downstream side. When the negative pressure in the intake passage rises above a certain value when the negative pressure in the intake passage rises above a certain value, the valve body of the annular groove part is communicated with the low-speed air passage The first feature is that the opening into the guide hole is closed, and the second air flow from the upstream second low-speed air passage toward the downstream second low-speed air passage is blocked.
[0007]
The low-speed fuel device for a carburetor according to the present invention branches the second low-speed air passage including the second low-speed air jet from the first low-speed air passage from the first low-speed air jet to the low-speed fuel jet. In a low-speed fuel device for a carburetor having an air-cut valve device that shuts off the second low-speed air passage when the negative pressure in the intake passage rises above a certain value in the second low-speed air passage, The valve device has a partition body that divides a low-speed air chamber in which a second low-speed air passage on the upstream side connected to the atmosphere opens, and a pressure receiving chamber connected to an intake passage on the downstream side of the throttle valve, and toward the low-speed air chamber A control hole composed of a large-diameter hole, a medium-diameter hole, and a small-diameter hole that are continuously provided, a ring-shaped bush that is fitted and disposed in the large-diameter hole and has a guide hole having the same diameter as the small-diameter hole, The end is a ring-shaped bush Therefore, the second low-speed air passage on the downstream side that opens into the annular groove formed in the medium-diameter hole and the downstream end is connected to the first low-speed air passage, and is slidably disposed in the small-diameter hole. The valve body is integrally attached to the compartment and can open and close the opening to the control hole of the annular groove, and when the negative pressure in the intake passage rises above a certain value, the valve body is ringed It is the second that the annular groove is closed by entering the guide hole of the cylindrical bush, and the second air flow from the second low-speed air passage on the upstream side to the second low-speed air passage on the downstream side is blocked. It is characterized by.
[0008]
According to the present invention, in addition to the second feature, the valve body is formed in a cylindrical shape and has a cylindrical portion having substantially the same diameter as the small-diameter hole, and a part of the cross-section of the cylindrical portion in the axial direction. A third feature is that the valve body is slidably guided by the small diameter hole and the guide hole of the ring-shaped bush.
[0009]
According to the first feature of the present invention, the air control of the air cut valve device is performed by the valve body, and the number of parts can be reduced and the valve body attached to the partition body is simply inserted into the valve body guide hole. It is sufficient to arrange them, and a reduction in manufacturing cost can be achieved.
[0010]
Further, according to the second feature of the present invention, since air control of the air cut valve device is performed by the valve body and the ring-shaped bush, the number of parts can be reduced, and further, the ring-shaped bush is fitted into the large-diameter hole. The valve body to be attached to the partition body after the combined arrangement may be inserted and arranged in the valve body guide hole via the guide hole of the ring-shaped bush, and the manufacturing cost can be reduced.
[0011]
Further, according to the third feature of the present invention, the valve body is always slidably guided by the small diameter hole and the guide hole of the ring-shaped bush, and the second low-speed air flow toward the second low-speed air passage on the downstream side. Since the opening / closing is controlled by the notch, the dynamic characteristics of the valve body can be improved.
[0012]
【Example】
An embodiment of a low speed fuel device for a carburetor according to the present invention will be described below with reference to FIG. In addition, about the same structure part as FIG. 5, the same code | symbol is used and description is abbreviate | omitted. Reference numeral 20 denotes a valve body guide hole having a circular cross section that opens toward the bottom of the low-speed air chamber 10 and has a diameter D. Reference numeral 21 denotes an annular groove at a substantially middle portion of the valve element guide hole 20, which has a diameter E larger than the diameter D of the valve element guide hole 20 and has a groove width F. Reference numeral 22 denotes a cylindrical valve body slidably disposed in the valve body guide hole 20, and the left end of the valve body 22 is integrated with the partition body 8 by a small diameter portion 22 </ b> A having a smaller diameter than the valve body 22. To be attached. The gap S formed between the small diameter portion 22A and the valve element guide hole 20 is set sufficiently larger than the effective area of the second low-speed air jet 18. The upstream side of the second low-speed air passage 12 </ b> B on the downstream side is opened in the annular groove 21.
[0013]
Here, looking again at the component configuration in the valve portion, the valve body 22 including the small diameter portion 22A is prepared, and the left end of the small diameter portion 22A is caulked and joined to the partition body 8. The valve element 22 is inserted into the valve element guide hole 20 through the opening of the valve element guide hole 20 to the low-speed air chamber 10.
[0014]
According to the low speed fuel device according to the present invention formed as described above, when the negative pressure generated in the intake passage 2 acting on the pressure receiving chamber 11 via the negative pressure introduction passage V is below a certain value, the compartment 8 is a compartment. Due to the spring force of the spring 17, it is on the low-speed air chamber 10 side, the valve body 22 is at the right position of the valve body guide hole 20, and the annular groove 21 is opened and held in the valve body guide hole 20. According to the above, the second low-speed air passage 12A on the upstream side and the second low-speed air passage 12B on the downstream side are the low-speed air chamber 10, the gap S between the valve element guide hole 20 and the small diameter portion 22A, the annular groove portion 21. The first low-speed air controlled by the first low-speed air jet 5 and the second low-speed air jet 18 controlled by the second low-speed air jet 18 are directed toward the low-speed fuel jet 6. Low-speed air combined with air is supplied, and thereby low-speed fuel (low-speed mixture) that satisfies the low-speed operation and the intermediate opening operation of the engine is supplied through the bypass hole 19 and the like. On the other hand, when the engine enters a sudden deceleration operation in which the engine is rapidly decelerated from the high opening operation, a very large negative pressure is generated in the intake passage 2A on the engine side from the throttle valve 4, and this large negative pressure is generated. Is introduced into the pressure receiving chamber 11 through the negative pressure introduction path V. When the negative pressure in the pressure receiving chamber 11 rises to a certain negative pressure value or more as described above, the partition body 8 including the small diameter portion 22A and the valve body 22 is largely opposed to the spring force of the partition body spring 8 to the pressure receiving chamber 11 side. According to this, the valve body 22 moves to the left in the valve body guide hole 20, and the left end portion of the valve body 22 is on the left side of the annular groove 21. It enters into the guide hole 20 and is held. According to the above, the valve element guide hole 20 on the left side of the annular groove 21 is blocked by the valve element 22. And the annular groove 21 is closed by the valve body 22. The second low-speed air flow flowing toward the second low-speed air passage 12B on the downstream side is blocked, and the amount of low-speed air flowing toward the low-speed fuel jet 6 is changed to the second low-speed air jet 18 minutes. It can be reduced considerably and the low-speed mixture concentration can be increased.
[0015]
As described above, according to the valve control part of the air cut valve device in the low speed fuel device of the carburetor according to the present invention, it is only necessary to prepare a single valve body 22, and therefore the number of parts can be reduced. The assembly is achieved simply by inserting the valve element 22 into the valve element guide hole 20. Thus, by reducing the number of parts and the number of assembly steps, the manufacturing cost can be greatly reduced and an inexpensive vaporizer can be provided. Further, according to the fact that the valve body 22 is directly attached to the partition body 8, the operation of the valve body 22 can be confirmed by operating the partition body 8, and the confirmation work at the time of manufacture is extremely simplified. Can be implemented reliably.
[0016]
Next, a second embodiment of the low speed fuel device for a carburetor according to the present invention will be described with reference to FIG. Only differences from FIG. 1 will be described. Reference numeral 30 denotes a control hole formed to open toward the bottom of the low-speed air chamber 10, and the control hole 30 is connected to the large-diameter hole 30A, the medium-diameter hole 30B, and the small-diameter hole 30C from the low-speed air chamber 10 side. Established. Reference numeral 31 denotes a ring-shaped bush having a guide hole 31 </ b> A drilled through in the center. The diameter of the guide hole 31 </ b> A is the same as the diameter D of the valve body guide hole 20. The ring-shaped bush 31 is fitted and disposed in the large-diameter hole 30 </ b> A of the control hole 30. According to the above, since the left end of the medium diameter hole 30B is closed by the right end of the ring-shaped bush 31, the medium diameter hole 30B forms the annular groove portion 21, and the downstream second groove is formed in the annular groove portion 21. The low-speed air passage 12B is opened upstream. The valve body 22 used in the first embodiment is used.
[0017]
As described above, in the present embodiment, the annular groove portion 21 is formed by the medium diameter hole 30B and the ring-shaped bush 31, and the formation of the annular groove portion 21 is easier than in the first embodiment. .
[0018]
A third embodiment of the present invention will be described with reference to FIGS. Only differences from FIG. 2 will be described. The valve body 40 has a cylindrical portion 40A that is slidably guided by the small-diameter hole 30C and the guide hole 31A of the ring-shaped bush 31, and a notch formed by a predetermined length from the left end of the cylindrical portion 40A toward the right in the axial direction. And a cutout portion 40B. The cross-sectional shape of the notch 40B is D-cut as shown in FIG. 4, and the notch area of the notch 40B is set larger than the effective area of the second low-speed air jet 18.
[0019]
Then, in a state where the negative pressure in the intake passage 2A is a predetermined value or less, the partition body 8 is pressed toward the low-speed air chamber 10 by the partition body spring 17, and the second low-speed air passage 12B on the downstream side is the annular groove portion 21, The second low speed air passage 12 </ b> A on the upstream side is communicated with the cutout portion 40 </ b> B and the low speed air chamber 10. In this state, the tubular portion 40A of the valve body 40 is slidably guided by the small diameter hole 30C and the guide hole 31A of the ring-shaped bush 31. Next, when the negative pressure in the intake passage 2A rises above a certain value, the partition body 8 moves to the pressure receiving chamber 11 side against the spring force of the partition body spring 17, and the cylindrical portion 40A moves to the ring-shaped bush. 31 enters the guide hole 31A. According to the above, the guide hole 31A is closed by the cylindrical portion 40A and the annular groove portion 21 is closed, whereby the low speed toward the second low-speed air passage 12B on the downstream side from the second low-speed air passage 12A on the upstream side. Air flow is blocked. According to this embodiment, since the valve body 40 is slidably guided by the small diameter hole 30C and the guide hole 31A in the entire movement range, the movement of the valve body 40 can be controlled smoothly, and dynamic characteristics and sliding durability are improved. It was a great improvement.
[0020]
【The invention's effect】
As described above, according to the low-speed fuel device for a carburetor according to the present invention, the air cut valve device includes a low-speed air chamber in which the second low-speed air passage on the upstream side connected to the atmosphere opens and the intake air on the downstream side of the throttle valve. A partition body that divides the pressure receiving chamber connected to the passage, a valve body guide hole that opens toward the low-speed air chamber, and a valve body guide hole that has a diameter larger than the diameter of the valve body guide hole and has a groove width An annular groove portion having an upstream end opened into the annular groove portion, and a downstream end connected to the second low-speed air passage on the downstream side connected to the first low-speed air passage, and slidable within the valve body guide hole Since it is formed with a valve body that is disposed and integrally attached to the partition body and can open and close the opening into the valve body guide hole of the annular groove portion, the number of parts and assembly man-hours can be reduced, So we could achieve a reduction in manufacturing costs A. And since a valve body is directly attached to a division body, operation check of a valve body can be performed easily. In addition, the air cut valve device includes a partition body that divides a low-speed air chamber in which the second low-speed air passage on the upstream side connected to the atmosphere opens and a pressure-receiving chamber connected to the intake passage on the downstream side of the throttle valve, and low-speed air A ring shape having a large-diameter hole, a medium-diameter hole, and a small-diameter hole that are continuous and open toward the room, and a guide hole having the same diameter as that of the small-diameter hole while being fitted to the large-diameter hole. The bush, the upstream end opens into an annular groove formed in the medium-diameter hole by the ring-shaped bush, and the downstream end has a second low-speed air passage on the downstream side connected to the first low-speed air passage, and the small-diameter hole The annular groove portion can be easily formed by being slidably disposed within the valve body and integrally attached to the partition body and formed by the valve body capable of opening and closing the opening into the control hole of the annular groove portion. Is. Further, the valve body is formed in a cylindrical shape, a cylindrical portion having substantially the same diameter as the small-diameter hole, and a notch in which a part of a cross section of the cylindrical portion is cut out by a predetermined length along the axial direction. If the valve body is slidably guided by the small diameter hole and the guide hole of the ring-shaped bush, the dynamic characteristics of the valve body and the sliding durability are improved.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of an essential part showing an embodiment of a fuel supply device for a carburetor according to the present invention.
FIG. 2 is a cross-sectional view of an essential part showing a second embodiment of the fuel supply apparatus for a carburetor according to the present invention.
FIG. 3 is a cross-sectional view of an essential part showing a third embodiment of the fuel supply apparatus for a carburetor according to the present invention.
4 is a cross-sectional view of a notch portion of the valve body in FIG. 3;
FIG. 5 is a cross-sectional view of a main part showing a conventional fuel supply device for a carburetor.
[Explanation of symbols]
2A Downstream intake passage 4 Throttle valve 8 Partition body 10 Low speed air chamber 12 Second low speed air passage 12A Upstream second low speed air passage 12B Downstream second low speed air passage 20 Valve body guide hole 21 annular Groove 30 Control hole 30A Large diameter hole 30B Medium diameter hole 30C Small diameter hole 31 Ring bush 31A Guide hole 40 Valve body 40A Cylindrical part 40B Notch

Claims (3)

The second low-speed air passage having the second low-speed air jet is branched from the first low-speed air passage from the first low-speed air jet to the low-speed fuel jet, and the negative pressure in the intake passage is supplied to the second low-speed air passage. In the low speed fuel device of the carburetor having the air cut valve device that shuts off the second low speed air passage when the air pressure rises above a certain value, the air cut valve device (A) A low-speed air chamber (10) in which two low-speed air passages (12A) are opened, and a pressure-receiving chamber (11) in which a negative pressure introduction passage (V) connected to the intake passage (2A) on the downstream side of the throttle valve (4 ) is opened. partition body for partitioning the bets and (8), the slow air chamber and the valve body guide hole opened toward the inside (10) (20), in the valve body guide hole (20), the valve body guide hole (20) Having a diameter (E) greater than the diameter (D) of A groove width (F) annular groove (21) having the upstream end is opened to the annular groove, the downstream end is contiguous to the first low speed air passage (7), internal to the second low-speed air jet (18 ) and downstream of the second low-speed air passage Ru equipped with (12B), the valve body guide the small diameter portion while being slidably disposed in the bore (22A) to integrally partition body (8) via the A valve body (22) attached and capable of opening and closing the opening into the valve body guide hole (20) of the annular groove (21) ,
When the negative pressure in the intake passage (2) is below a certain value, the annular groove (21) is held open toward the valve element guide hole (20) by the valve element (22), and the second low-speed air passage on the upstream side (12A) and the second low-speed air passage (12B) on the downstream side communicate with each other via the gap (S) between the valve body guide hole (20) and the small diameter portion (22A), the annular groove portion (21), When the negative pressure in the intake passage (2) rises above a certain value, the valve body (22) closes the opening of the annular groove (21) into the valve body guide hole (20), and the upstream side A low-speed fuel device for a carburetor, wherein the second air flow from the second low-speed air passage (12A) toward the second low-speed air passage (12B) on the downstream side is interrupted.   The second low-speed air passage having the second low-speed air jet is branched from the first low-speed air passage from the first low-speed air jet to the low-speed fuel jet, and the negative pressure in the intake passage is supplied to the second low-speed air passage. In the low speed fuel device of the carburetor having the air cut valve device that shuts off the second low speed air passage when the air pressure rises above a certain value, the air cut valve device (A) A partition body (8) that divides a low-speed air chamber (10) in which two low-speed air passages (12A) are opened and a pressure receiving chamber (11) connected to an intake passage (2A) on the downstream side of the throttle valve (4) A control hole (30) comprising a large-diameter hole (30A), a medium-diameter hole (30B), and a small-diameter hole (30C) that are connected and opened toward the low-speed air chamber (10), and the large-diameter hole The same as the small diameter hole (30C) A ring-shaped bush (31) having a guide hole (31A) with a diameter and an upstream end open into an annular groove (21) formed in the medium-diameter hole (30B) by the ring-shaped bush (31), and a downstream end Is slidably disposed in the small-diameter hole and is integrally attached to the partition body (8) and the second low-speed air passage (12B) downstream from the first low-speed air passage (7). And the valve body (40) capable of opening and closing the opening into the control hole (30) of the annular groove (21), and when the negative pressure in the intake passage (2A) rises above a certain value, The annular groove is closed by entering the valve body (40) into the guide hole (31A) of the ring-shaped bush (31), and the second low-speed air passage (12A) on the upstream side is second low-speed on the downstream side. The second air flow toward the air passage (12B) is blocked. Slow fuel system of equalizer.   The valve body is formed in a cylindrical shape and has a cylindrical portion (40A) having substantially the same diameter as the small-diameter hole (30C), and a part of a cross section of the cylindrical portion (20A) is predetermined along the axial direction. The valve body (40) is slidably guided by the small diameter hole (30C) and the guide hole (31A) of the ring-shaped bush (31). The low-speed fuel device for a carburetor according to claim 2.

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