JPH036845Y2 - - Google Patents

Description

[Detailed explanation of the invention] A. Purpose of the invention (1) Industrial application field The present invention is based on a carburetor, in particular, a float chamber is defined at the lower part of the carburetor body having an intake duct and between the carburetor body. The float chamber body consisting of is removably connected,
A fuel nozzle facing the intake passage communicates with the float chamber via a fuel jet, and a float chamber is provided between the float chamber and a fuel passage formed in the carburetor body to supply fuel to the float chamber. The float valve is equipped with a float valve that opens and closes in response to the rise and fall of a float housed in the float valve.

(2) Prior art In this type of carburetor, it is desirable to supply fresh fuel to the fuel jet when starting the engine, and from that point of view, a branched fuel passage branching from the outlet side of the float valve is connected to the vicinity of the fuel jet. An extended version has been proposed (for example, in 1973-
(See Publication No. 43286).

(3) Problems to be solved by the invention In the above proposal, in order to prevent the fresh fuel supplied into the float chamber from the branch fuel passage from mixing with the old fuel remaining in the float chamber, A separator that divides the float chamber into two upper and lower chambers is specially fixed to the protrusion on the lower surface of the carburetor body that protrudes into the float chamber, and the work of fixing the separator to the carburetor body is troublesome. In addition, there was a problem in that when the float chamber body was removed from the carburetor main body, it interfered with maintenance of the float and float valve.

The present invention was proposed in view of the above, and aims to provide a carburetor that can provide only fresh fuel to the fuel jet and improve starting performance without causing the above problems. Structure of the invention (1) Means for solving the problem According to the present invention, in order to achieve the above object, a float chamber is defined between the lower part of the carburetor body having the intake passage and the carburetor body. A fuel nozzle facing the intake passage is connected to the float chamber through a fuel jet, and a fuel nozzle is formed in the carburetor body to supply fuel to the float chamber. In the carburetor, a float valve is interposed between the passage and the float chamber, and the float valve opens and closes in response to the rise and fall of a float housed in the float chamber. and a cylindrical large-diameter upper part connected to the upper end of the small-diameter lower part via a step, and an upper chamber in which the float is arranged and an opening communicating with the fuel jet are located in the upper part. In order to partition the float chamber into a lower chamber and a lower chamber, an outer circumferential surface of a synthetic resin separator formed in an upwardly convex bowl shape is fitted onto the inner circumferential surface of the small diameter lower portion, and a separator made of synthetic resin is fitted into the stepped portion. , an outward facing flange connected to the outer periphery of the separator is engaged, and the separator has a communication pipe section for communicating between the bottom of the lower chamber and the upper chamber, and the opening of the separator. A passage forming part for forming a communication passage with an outlet located nearby and an air vent pipe part for communicating a part of the lower chamber above the opening with an air part in an upper part of the upper chamber are integrally formed. The lower end of a connecting pipe portion, which is protruded from the lower surface of the carburetor body facing into the float chamber and becomes a part of the fuel passage from the outlet of the float valve, is pulled out at the communication passage entrance of the passage forming portion. It is inserted removably.

(2) Effect Fresh fuel can be efficiently supplied from the float valve outlet to the vicinity of the opening of the lower chamber of relatively small capacity through the connecting pipe and the communication passage, and old fuel at the bottom of the lower chamber can be efficiently supplied. Since the area near the opening can be filled with fresh fuel by discharging it into the upper chamber through the communication pipe, only fresh fuel can be supplied to the fuel jet leading to the opening, improving starting performance. do. Furthermore, even if air should enter the lower chamber, it can be released through the air vent pipe section into the air section of the upper chamber.
This air can be effectively prevented from staying in the lower chamber above the opening and entering the fuel jet side through the opening.

In particular, the separator, which is formed in the shape of a bowl convex upward, has an outer circumferential surface fitted into the inner circumferential surface of the bottomed cylindrical small-diameter lower part of the float chamber body, and an outward-facing flange on the outer circumferential edge of the separator. Since the part is engaged with the step part of the float chamber body, it can be fixed to the float chamber body very easily without using a special fixing tool. Moreover, when the float chamber body is separated from the carburetor body, the separator can be taken out together with the float chamber body. In addition, when reattaching the float chamber body to the carburetor body, the connection pipe portion on the carburetor body side is simply inserted into the communication passage entrance of the separator that has been fitted in advance to the float chamber body, and the connection is completed.

(3) Embodiment Hereinafter, an embodiment of the present invention will be explained with reference to the drawings. First, as shown in FIG. A bench lily portion 4 is provided along the central portion. Further, a choke valve 5 is disposed in the intake passage 2 upstream of the bench lily portion 4, and a throttle valve 6 is disposed downstream of the bench lily portion 4. The valve shaft 7 of the choke valve 5 and the valve shaft 8 of the throttle valve 6 are rotatably supported on the carburetor body 1 with their upper ends projecting upward, and the upper ends of both valve shafts 7, 8 are Levers 9 and 10 are each fixed.

A float chamber body 12 is coupled to the lower portion of the carburetor body 1 to define a float chamber 11 therebetween. In addition, a bench lily portion 4 is provided at the bottom of the carburetor main body 1.
A holder 13 extending toward the bottom of the float chamber body 12 is integrally provided at a portion corresponding to the float chamber body 12, and a fuel nozzle 14, a bleed pipe 15, and a fuel jet 16 are mounted within this holder 13. That is, the fuel nozzle 14 is connected to the bench lily portion 4.
A bleed pipe 15 is integrally and coaxially connected to the lower part of the fuel nozzle 14 . A fuel jet 16 that contacts the lower end of the bleed pipe 15 is screwed in the middle of the holder 13, and the bleed pipe 15 and the fuel nozzle 14 are connected to each other.
is clamped and fixed between the upper support step 17 in the holder 13 and the fuel jet 16.

A female thread 18 is formed on the inner surface of the lower end of the holder 13, and this female thread 18 is provided with the float chamber body 1.
A bolt 19 inserted through the center of the bottom of the carburetor body 1 is screwed, and by tightening the bolt 19, the carburetor main body 1 and the float chamber body 12 are firmly connected. Moreover, the head of the bolt 19 and the float chamber body 12
A sealing member 20 is interposed between the outer surface and the outer surface.

Furthermore, an opening 21 for introducing fuel into the fuel jet 16 is formed in the side wall of the holder 13 at a position facing the lower end of the fuel jet 16.

A fuel passage 22 for guiding fuel into the float chamber 11 is bored in the carburetor body 1 . One end of this fuel passage 22 is connected to the fuel tank 2 via a conduit 23.
4, and a cutoff valve 25 is disposed in the middle of this conduit 23. The other end of the fuel passage 22 is disposed above the float chamber 11, and a float valve 26 is interposed between the other end of the fuel passage 22 and the inside of the float chamber 11.

In FIG. 2, the float valve 26 has a valve hole 27 that communicates with the other end of the fuel passage 22, and a valve hole 27 that communicates with the other end of the fuel passage 22.
The valve body 29 is provided with a valve body 29 that can be seated on a valve seat portion 28 provided at the lower end edge of the valve body 29 . The valve hole 27 is connected to the fuel passage 2
A large-diameter guide hole 30 extending downward from the other end of the valve hole 27 and coaxially connected to the valve hole 27 is bored in the carburetor body 1 . The lower end of this guide hole 30 is connected to the float chamber 11.
The valve shaft 31 is open to the inside, and a valve shaft 31 is inserted into the guide hole 30 so as to be vertically movable.

The valve stem 31 is basically formed into a round rod shape made of synthetic resin, and is movable up and down within the guide hole 30. At the upper end of this valve stem 31, there is a valve body 29 whose diameter becomes smaller as it goes upward. are integrally provided.

Referring again to FIG. 1, an annular float 32 surrounding the holder 13 is housed in the float chamber 11, and the base 33 of the float 32 is swingable by a horizontal support shaft 34 below the float valve 26. is supported by The base 33 of this float valve 26
A locking portion 35 is provided on the valve shaft 3.
An engaging neck portion 36 provided at the lower end of 1 engages with the locking portion 35. Therefore, as the float 32 swings due to the rise and fall of the fuel oil level in the float chamber 11, the valve body 29 of the float valve 26 moves up and down, and the valve hole 27 is opened and closed.

A separator 37 is disposed inside the float chamber 11, and the separator 37 allows the float chamber 11 to
The inside is divided into an upper chamber 38 and a lower chamber 39. The float 32 is placed in the upper chamber 38, and the holder 1
The opening 21 of No. 3 is located in the upper part of the lower chamber 39 . Referring to FIGS. 3 and 4 together, the separator 37 has a bowl-shaped portion 4 that swells upward.
0, a cylindrical portion 41 extending upward from the outer end of the bowl-shaped portion 40, and a flange portion 42 projecting outward from the upper end of the cylindrical portion 41, and is formed of synthetic resin.

On the other hand, the float chamber body 12 has a cylindrical large-diameter upper part 43 with both ends open, and a cylindrical small-diameter lower part 4 with a bottom.
4 are connected to each other via a stepped portion 45,
The separator 37 is fitted into the float chamber body 12 from above by fitting the cylindrical part 41 into the inner peripheral surface of the small diameter lower part 44 with the collar part 42 in contact with the step part 45.

A fitting cylindrical portion 46 extending upward is integrally provided at the center of the bowl-shaped portion 40 . The inner diameter of this fitting cylinder part 46 is set slightly smaller than the outer diameter of the holder 13, and a notch 4 is provided in the upper part of the fitting cylinder part 46.
7 is provided. Therefore, when the holder 13 is fitted into the fitting cylinder part 46, the fitting cylinder part 46 is forcibly expanded radially outward from its natural state and exerts a resilient force radially inward. do. This results in
The position of the separator 37 within the float chamber 11 is stably maintained.

Further, the top portion 48 of the bowl-shaped portion 40 is located at a position offset from the fitting cylinder portion 46, and the top portion 48 has an air vent pipe portion 50 that reaches the air portion 49 above the fuel oil level in the upper chamber 38. Integrated. Therefore, the opening 21 of the lower chamber 39
The upper part and the air part 49 communicate with each other via an air vent pipe part 50. Furthermore, an external air vent hole 51 is formed in the carburetor body 1 to communicate the air portion 49 to the outside.

Further, a pair of communicating tube portions 52 extending downward are integrally provided on the peripheral edge of the bowl-shaped portion 40.
The lower part of the upper chamber 38 and the lower part of the lower chamber 39 are communicated with each other via a communication passage 53 provided in the communication tube part 52.

On the downstream side of the valve seat portion 28 of the float valve 26, a hole 54 is opened in the inner surface of the guide hole 30 and extends diagonally downward toward the bleed pipe 15 side. The lower end of this hole 54 communicates with the upper end of a hole 55 extending vertically, and the upper end of a connecting pipe 56 as a connecting pipe portion is press-fitted into this hole 55 and held therein. On the other hand, a passage forming part 57 is integrally provided in the bowl-shaped part 40 of the separator 37 corresponding to the connecting pipe 56, and the lower part of the connecting pipe 56 is
It is removably inserted into the open upper end, ie, the entrance, of the communication passage 57a that penetrates the passage forming part 57. As a result, the first branch passage 5 serves as a fuel guide passage from the outlet side of the float valve 26 to the upper part of the lower chamber 39.
8 is formed, and the lower end of the first branch passage 58, that is, the outlet (open lower end) of the communication passage 57a, is connected to the lower chamber 39 at a position close to the opening 21 of the holder 13.
It is open at the top.

On the other hand, in the float valve 26, a second branch passage 5 is provided between the outer surface of the valve shaft 31 and the inner surface of the guide hole 30.
9 is formed, and this second branch passage 59 communicates with the upper chamber 38.

Next, to explain the operation of this embodiment, when the engine is stopped and left for a long period of time, the shutoff valve 25 is generally closed. Light components of fuel such as gasoline stored inside the tank evaporate, causing the fuel oil level to drop. In response to this decrease in the fuel oil level, the float 32 swings downward, and the float valve 26 closes. Therefore, the fuel remaining in the conduit 23 and the fuel passage 22 on the downstream side of the cutoff valve 25 is introduced into the float chamber 11, replacing the air in the float chamber 11. At this time, from the outlet side of the float valve 26, the first branch passage 58 and the second branch passage 5 are
9, a part of the fuel flows into the lower chamber 39 through the first branch path 58, and the amount of fuel in the lower chamber 39 that flows in flows through the communication path 53 into the upper chamber 38. The remaining fuel flows into the upper chamber 38 via the second branch 59.

Due to long-term operation, the fuel oil level in the float chamber 11 remains low, that is, the float valve 2
Assume that the shutoff valve 25 is opened in order to start the engine while the shutoff valve 25 remains open.
By opening the shutoff valve 25, fuel is supplied from the fuel tank 24 into the conduit 23, and the air in the conduit 23 and fuel passage 22 on the downstream side of the shutoff valve 25 is forced into the float chamber 11 by the fuel. be caught. That is, a part of the air is guided into the lower chamber 39 through the first branch path 58, and the remaining air is guided into the upper chamber 38 through the second branch path 59. Lower chamber 3
The air that has entered the chamber 9 gathers at the top of the lower chamber 39, where the air vent pipe section 5 opens at its lower end.
Since the air can escape to the air portion 49 of the upper chamber 38 through the air, the air stays in the lower chamber 39 above the opening 21 and
It is possible to effectively prevent air from entering the fuel jet 16 side through the air, thereby preventing intermittent fuel supply to the fuel jet 16 due to the air entry.

A portion of the fuel that flows into the float chamber 11 following the above-mentioned air flows into the upper part of the lower chamber 39 via the first branch passage 58, and the amount of old fuel that flows into the lower chamber 39 is It is discharged from the lower part to the upper chamber 38 via the communication path 53. Therefore, the area around the opening 21 is filled with fresh fuel.

In this state, when the engine is started by closing the choke valve 5, fresh fuel is drawn into the intake passage 2 from the fuel nozzle 14 via the fuel jet 16.
Therefore, the starting performance of the engine can be improved.

In the above embodiment, the outlet of the float valve 26 is branched into the first branch path 58 and the second branch path 59, but the present invention does not have such a branch, and the fuel from the float valve 26 is All lower chamber 3
It can also be applied to those designed to lead within 8.

C. Effects of the invention As described above, according to the invention, a float chamber body defining a float chamber between the carburetor body and the lower part of the carburetor body having an intake passage is detachably connected to the lower part of the carburetor body, A fuel nozzle facing the intake passage communicates with the float chamber via a fuel jet, and a float chamber is provided between the float chamber and a fuel passage formed in the carburetor body to supply fuel to the float chamber. In a carburetor equipped with a float valve that opens and closes in response to the rise and fall of a float housed in the float chamber, the float chamber body has a small-diameter lower portion in the form of a bottomed cylinder, and a stepped portion at the upper end of the small-diameter lower portion. In order to divide the float chamber into an upper chamber in which the float is arranged and a lower chamber in which an opening communicating with the fuel jet is located in the upper part, The outer circumferential surface of a synthetic resin separator formed in an upwardly convex bowl shape is fitted into the inner circumferential surface of the small diameter lower part, and the outer circumferential surface of the separator is connected to the outer circumferential edge of the separator. The flange of the separator is engaged with the separator, and the separator includes a communication pipe portion for communicating between the bottom of the lower chamber and the upper chamber;
a passage forming part for forming a communication passage having an outlet located near the opening; and an air vent pipe part for communicating a part of the lower chamber above the opening with an air part in the upper part of the upper chamber. is integrally formed, and at the entrance of the communication passage of the passage forming part, there is a connecting pipe part which is protruded from the lower surface of the carburetor body facing into the float chamber and becomes a part of the fuel passage from the outlet of the float valve. Since the lower end is removably inserted, fresh fuel can be efficiently supplied from the float valve outlet to the vicinity of the opening of the lower chamber having a relatively small capacity through the connecting pipe section and the communication passage, and
The old fuel at the bottom of the lower chamber can be removed to the upper chamber through the communication pipe section, filling the vicinity of the opening with fresh fuel, thereby ensuring that only fresh fuel is supplied to the fuel jet leading to the opening. In this way, starting performance can be improved. Furthermore, even if air should enter the lower chamber, it can escape through the air vent pipe section to the air section of the upper chamber, so that air will not stay in the lower chamber above the opening. This effectively prevents air from entering the fuel jet side through the opening, and therefore prevents intermittent supply of fuel to the fuel jet due to air entry.

In particular, the separator, which is formed in the shape of a bowl convex upward, has its outer circumferential surface fitted into the inner circumferential surface of the bottomed cylindrical small-diameter lower part of the float chamber body, and the outer circumferential edge of the separator has an outward facing flange. Since the part is engaged with the stepped part of the float chamber body, it can be fixed to the float chamber body very easily without using a special fixing tool, and the fixing structure is simple, reducing costs and facilitating assembly. It can contribute to improvement. Moreover, when the float chamber body is separated from the carburetor body, the separator can be taken out together with it, so there is no possibility that the separator will get in the way when attaching/detaching or maintaining the float or float valve. Efficiency can be improved. In addition, when reattaching the float chamber body to the carburetor body, the connection pipe portion on the carburetor body side is simply inserted into the communication passage entrance of the separator into which the float chamber body has been fitted in advance, and the Since the connection is completed, the workability is very good.

Furthermore, since the separator, which has a complex shape and integrally includes the passage forming part, air vent pipe part, communication pipe part, collar part, etc., is made of synthetic resin, it can be easily obtained by integral molding. Furthermore, when fitting the separator into the float chamber body, the separator and the inner surface of the float chamber body have good compatibility and the work is easy.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention; FIG. 1 is a longitudinal sectional view, FIG. 2 is an enlarged longitudinal sectional view of the main part of FIG. 1, FIG. 3 is an enlarged plan view of a separator, and FIG. FIG. 4 is a sectional view taken along the - line in FIG. 3; DESCRIPTION OF SYMBOLS 1... Carburetor body, 2... Intake path, 11... Float chamber, 12... Float chamber body, 14... Fuel nozzle, 16... Fuel jet, 22... Fuel passage, 26... Float valve, 37...Separator,
38... Upper chamber, 39... Lower chamber, 42... Flange, 43... Large diameter upper part, 44... Small diameter lower part, 45
. . . Stepped portion, 49 . . . Air portion, 50 . . . Air vent pipe portion, 52 .

Claims (1)

[Scope of utility model registration request] A float chamber body 12 defining a float chamber 11 between the carburetor body 1 and the carburetor body 1 is detachably connected to the lower part of the carburetor body 1 having an intake passage 2, and a fuel nozzle 14 facing the intake passage 2 is attached. is the fuel jet 16
Between the float chamber 11 and a fuel passage 22 which is bored in the carburetor body 1 in order to communicate with the float chamber 11 via the float chamber 11 and supply fuel to the float chamber 11, float 3
A float valve 26 that opens and closes in response to the elevation of the float valve 26.
In the carburetor, the float chamber body 12 includes a bottomed cylindrical small-diameter lower part 44 and a cylindrical large-diameter upper part 43 connected to the upper end of the small-diameter lower part 44 via a step 45. The float 3 is composed of
In order to divide the inside of the float chamber 11 into an upper chamber 38 in which the fuel jet 2 is disposed, and a lower chamber 39 in which the opening 21 communicating with the fuel jet 14 is located at the upper part, the inner circumferential surface of the small diameter lower part 44 is The outer circumferential surface of the synthetic resin separator 37 formed in the shape of a bowl convex upward is fitted, and an outward facing flange 42 connected to the outer circumferential edge of the separator 37 is engaged with the stepped portion 45. The separator 37 has the lower chamber 39
a communication pipe section 52 for communicating between the bottom of the chamber and the upper chamber 38; a passage forming section 57 for forming a communication channel 57a whose outlet is located near the opening 21; An air vent pipe section 50 is formed integrally with the air vent pipe section 50 for communicating the upper part of the opening section 21 with the air section 49 in the upper part of the upper chamber 38. The lower end of a connecting pipe portion 56 that protrudes from the lower surface of the main body 1 facing into the float chamber 11 and becomes a part of the fuel passage 22 from the outlet of the float valve 26 is removably inserted. Yes, vaporizer.