JP5118527B2 - Engine fuel supply system - Google Patents

Description

  The present invention relates to an engine fuel supply apparatus including a fuel increase pump that increases the amount of fuel led to a carburetor.

A fuel supply device for an engine mixes fuel with air in a carburetor, and supplies the mixed mixture from the carburetor into a cylinder.
When the engine is suddenly accelerated from the idling state (when the engine speed is increased rapidly), the fuel supply is delayed due to a sudden change in the air flow rate, the mixture becomes temporarily lean, and the engine fails to accelerate or stops. It is possible.

As a countermeasure, there is an insulator provided between the engine and the carburetor to prevent the heat of the engine from being transmitted to the carburetor, and a fuel increase pump is provided in the insulator.
By providing the fuel increase pump, it is possible to temporarily increase the amount of fuel in the air-fuel mixture during acceleration of the engine (see, for example, Patent Document 1).
JP 2007-71054 A

In the engine fuel supply device of Patent Document 1, an air-fuel mixture supply flow path is provided in the lower half of the insulator part, an air flow path is provided in the upper half part, and a fuel increase pump is provided in the lower part of the insulator part. Yes.
The air flow path communicates with the negative pressure chamber of the fuel increase pump via the air introduction path.

According to this engine fuel supply device, in the idling state, the throttle valve has a small opening, so that the air introduction path has a negative pressure. When the air introduction path becomes negative pressure, the negative pressure chamber of the fuel increase pump becomes negative pressure.
Therefore, the negative pressure diaphragm of the fuel increase pump is moved to the negative pressure chamber side by the spring force of the spring member.

When the throttle valve is opened from this state and the acceleration is accelerated rapidly, air is introduced into the air introduction path and air is introduced into the negative pressure chamber of the fuel booster pump.
The negative pressure diaphragm of the fuel increase pump is instantaneously moved to the pump chamber side against the spring force of the spring member. The air in the pump chamber is pumped to the pressurizing chamber through the communication channel.

The pressurizing diaphragm is pushed out to the fuel chamber side, and the fuel in the fuel chamber is supplied in a state of being temporarily increased in the mixture supply passage.
Therefore, when the engine is suddenly accelerated from the idling state, the amount of fuel in the air-fuel mixture can be temporarily increased with good responsiveness in response to the operation of the throttle valve.

However, in the engine fuel supply device of Patent Document 1, it is necessary to provide an air flow path in the upper half of the insulator portion in order to provide the fuel increase pump in the insulator portion.
That is, the fuel supply device for the engine needs to be provided with two flow paths (mixture supply flow path and air flow path) in the insulator portion, and it has been difficult to make the fuel supply apparatus compact.

  The present invention provides an engine fuel supply device that can increase the amount of fuel in an air-fuel mixture with high responsiveness in response to the operation of a throttle valve when the engine is accelerated rapidly, and can be downsized. The task is to do.

The invention according to claim 1, pressure diaphragm partitioning the fuel chamber and the pressure chamber is provided in the carburetor, the fuel supply system for an engine which increase the amount of fuel derived from the fuel chamber by pressurizing the pressure chamber The air- fuel mixture mixed with the fuel in the carburetor is disposed between the carburetor and the engine to insulate the heat of the engine and to provide an air flow path for introducing air to the engine. An insulator portion provided with an air-fuel mixture supply channel that leads to the gas generator, a pump chamber that is incorporated in the insulator portion and disposed above the air-fuel mixture supply channel and pressurizes the pressurizing chamber, and the pump A fuel increase pump in which the negative pressure chamber is adjacent to the chamber via a negative pressure diaphragm, and downward from the lower portion of the negative pressure chamber toward the mixture supply passage Extending the negative pressure chamber flow path for introducing a part of the air-fuel mixture from the air-fuel mixture supply channel into the negative pressure chamber, Bei example, said negative pressure chamber flow path, and the air-fuel mixture supply channel A first negative pressure chamber flow path formed substantially vertically, and a second negative pressure chamber flow formed through the first negative pressure chamber flow path and the negative pressure chamber and substantially parallel to the air-fuel mixture supply flow path The first negative pressure chamber flow path and the second negative pressure chamber flow path are formed integrally with the insulator portion .

In the invention according to claim 1, a part of the air-fuel mixture is introduced from the air-fuel mixture supply flow path into the negative pressure chamber through the flow path.
Therefore, when the throttle valve opening is increased from the idling state and accelerated rapidly (when the engine speed is increased rapidly), a large amount of air is instantaneously introduced into the carburetor.

Fuel is mixed with a large amount of air to form an air-fuel mixture. The air-fuel mixture is instantaneously guided to the air-fuel mixture supply channel.
A part of the introduced large amount of air-fuel mixture is instantaneously guided to the negative pressure chamber of the fuel booster pump through the negative pressure chamber flow path, and the fuel booster pump operates.

By operating the fuel increasing pump, the air in the pump chamber is pumped to the pressurizing chamber, and the fuel in the fuel chamber is supplied to the carburetor in a temporarily increased state.
As a result, it is possible to temporarily increase the amount of fuel contained in the air-fuel mixture in response to the operation of the throttle valve, thereby preventing the engine from being poorly accelerated or stopped.

On the other hand, when the throttle valve is maintained at a constant opening, the air-fuel mixture supply passage is in a negative pressure state. The negative pressure chamber of the fuel increase pump becomes negative because the air-fuel mixture supply flow path is in a negative pressure state.
Therefore, the operation of the fuel increase pump is stopped, and the air in the pump chamber is not pumped to the pressurizing chamber.
As a result, the engine is driven in a normal state in which the amount of fuel contained in the air-fuel mixture is not temporarily increased.

By the way, as described above, when the throttle valve is opened and the acceleration is rapidly performed, the air-fuel mixture is guided to the negative pressure chamber of the fuel booster pump.
For this reason, it is conceivable that the fuel contained in the air-fuel mixture accumulates in the negative pressure chamber of the fuel increase pump, and the air-fuel ratio of the air-fuel mixture supplied from the carburetor to the engine fluctuates.
When the air-fuel ratio of the mixture varies, it is difficult to drive the engine smoothly.

Therefore, in claim 1, a fuel increase pump is disposed above the mixture supply passage, and the passage is extended from the lower part of the negative pressure chamber toward the mixture supply passage.
Therefore, when the atomized fuel is introduced into the negative pressure chamber and dropped into the lower portion of the negative pressure chamber, it can be returned to the air-fuel mixture supply flow channel through the flow channel.
As a result, the air-fuel ratio of the air-fuel mixture can be prevented from fluctuating, and the engine can be driven smoothly.

Further, by introducing a part of the air-fuel mixture from the air-fuel mixture supply passage through the passage to the negative pressure chamber, the fuel increase pump can be operated using the air-fuel mixture in the air-fuel mixture supply passage.
Thereby, in order to operate the fuel increase pump, it is not necessary to provide an air flow path in the insulator portion as in the prior art, so that the size can be reduced.

The best mode for carrying out the present invention will be described below with reference to the accompanying drawings.
FIG. 1 is a principle view showing an engine fuel supply apparatus according to the present invention.
The fuel supply device 10 for the engine includes a carburetor 11 that mixes fuel 12 into air, an insulator portion 15 interposed between the carburetor 11 and the engine 14, and a fuel increase pump 16 incorporated in the insulator portion 15. It has.
The carburetor 11 and the insulator portion 15 are attached to the engine 14 with bolts 18 and 18 (see FIGS. 2 and 3).

Here, the fuel supply apparatus 10 of an engine is an apparatus used for liquid fuel as an example.
As shown in FIG. 2, the fuel supply apparatus 10 for the engine can include a carburetor-side pump 29 in the side portion 11 a on the fuel increase pump 16 side of the carburetor 11.
However, in the principle diagram of FIG. 1, in order to facilitate understanding of the fuel supply device 10 of the engine, for convenience, the fuel increase pump 16 is disposed directly above the insulator portion 15, and the carburetor side pump 29 is disposed in the carburetor. 11 is shown in a state of being provided in the lower part.

  The vaporizer 11 includes a body (main body) 21 of the vaporizer 11, a mixing flow path 22 provided in the body 21, a throttle valve 23 provided in the mixing flow path 22, and a venturi portion 24 of the mixing flow path 22. A fuel nozzle 25 facing the fuel storage chamber 26 communicated with the fuel nozzle 25, a pressurization chamber 27 provided adjacent to the fuel storage chamber 26, and a pressurization diaphragm that partitions the pressurization chamber 27 and the fuel storage chamber 26 28 and a pump chamber flow path 31 that connects the pressurizing chamber 27 to a pump chamber 66 (described later).

The pressurizing chamber 27, the fuel storage chamber 26, and the pressurizing diaphragm 28 constitute a carburetor-side pump 29.
The fuel storage chamber 26 communicates with a fuel tank (not shown) via a fuel supply channel (not shown).
The pump chamber flow path 31 will be described in detail with reference to FIGS.

According to the carburetor 11, the amount of air flowing through the venturi portion 24 of the mixing channel 22 is adjusted by operating the throttle valve 23 and adjusting the opening of the mixing channel 22.
When the air flows through the venturi portion 24 as shown by the arrow, the fuel 12 is guided from the fuel nozzle 25 to the venturi portion 24.

Here, by pressing the pressurizing chamber 27 and pressing the pressurizing diaphragm 28 toward the fuel storage chamber 26, the fuel 12 can be forcibly led out from the fuel nozzle 25 to the venturi portion 24.
By forcibly leading the fuel 12 to the venturi 24, the amount of fuel led to the venturi 24 can be increased.

Next, actual positions of the fuel increase pump 16 and the carburetor side pump 29 will be described in detail with reference to FIG.
FIG. 2 is a side view of an engine fuel supply apparatus according to the present invention.
The carburetor 11 is attached in a state where the support shaft 33 of the throttle valve 23 is arranged vertically.
The carburetor 11 is provided with a fuel increase pump 16 via an insulator portion 15 (see FIG. 1).

The fuel increase pump 16 is disposed in a state offset to the side with respect to the mixing flow path 22 of the vaporizer 11 and on the upper side.
More specifically, as shown in FIG. 4, the fuel increase pump 16 has its center 32 offset from the center 34 of the air-fuel mixture supply flow path 36 to the side, that is, the side 11 a side, and upward. Is arranged.

Further, the carburetor 11 is provided with a carburetor-side pump 29 on the side portion 11a on the fuel increase pump 16 side.
By providing the carburetor side pump 29 on the side portion 11 a on the fuel increase pump 16 side, the carburetor side pump 29 is disposed in the vicinity of the fuel increase pump 16.

Returning to FIG. 1, the insulator portion 15 is interposed between the carburetor 11 and the engine 14 to insulate the heat of the engine 14.
The insulator unit 15 includes an air-fuel mixture supply channel 36 that communicates with the mixing channel 22 and the intake air channel 35, and a negative pressure chamber channel (channel) that communicates the gas mixture supply channel 36 with the negative pressure chamber 65. 38.
The negative pressure chamber 65 is formed by a storage portion 45 and a negative pressure diaphragm 57 as will be described later.

The intake passage 35 is a passage formed in the engine 14 and communicated with a cylinder (not shown).
The air-fuel mixture supply flow path 36 is a flow path that guides the air-fuel mixture 13 mixed with the liquid fuel 12 in the mixing flow path 22 to the intake flow path 35.

FIG. 3 is a perspective view showing a state in which the plate is disassembled from the insulator portion of the fuel supply apparatus for an engine according to the present invention, and FIG. 4 is a view taken along the arrow 4 in FIG.
The negative pressure chamber flow path 38 is connected to the insulator portion 15 so as to communicate with the negative pressure chamber 65 (see also FIG. 1) and the air-fuel mixture supply flow path 36, and the flow channel groove 43 of the first negative pressure chamber flow path 41 and The second negative pressure chamber channel 42 is integrally formed.

The first negative pressure chamber channel 41 is a channel formed by forming a channel groove 43 substantially perpendicular to the air-fuel mixture supply channel 36 and closing the channel groove 43 with a plate 47.
The first negative pressure chamber flow channel 41 is a flow channel that communicates the second negative pressure chamber flow channel 42 and the air-fuel mixture supply flow channel 36.
As shown in FIG. 1, the plate 47 is a plate material interposed between the insulator portion 15 and the engine 14.

The second negative pressure chamber flow path 42 is a flow path that is formed substantially parallel to the air-fuel mixture supply flow path 36 and communicates with a lower portion 45 a (see FIG. 1) of the storage section 45 provided in the insulator section 15.
The lower part 45 a of the storage part 45 also constitutes the lower part of the negative pressure chamber 65.

As shown in FIG. 4, the first negative pressure chamber flow channel 41 has a downward slope with an inclination angle θ from the end 42 a (see FIG. 1) of the second negative pressure chamber flow channel 42 toward the mixture supply flow channel 36. It is linearly extended downward.
In other words, the first negative pressure chamber flow path 41 is linearly extended upward from the mixture supply flow path 36 toward the end 42a of the second negative pressure chamber flow path 42 with an upward slope of the inclination angle θ. ing.
The reason why the first negative pressure chamber channel 41 is formed at the inclination angle θ will be described later.

The negative pressure chamber 65 and the air-fuel mixture supply flow path 36 are communicated with each other through a negative pressure chamber flow path 38 constituted by the first and second negative pressure chamber flow paths 41 and 42.
By connecting the negative pressure chamber 65 and the air-fuel mixture supply flow path 36 through the negative pressure chamber flow path 38, a part of the air-fuel mixture 13 can be introduced into the negative pressure chamber 65 from the air-fuel mixture supply flow path 36. .

By introducing a part of the air-fuel mixture 13 into the negative pressure chamber 65 through the negative pressure chamber flow path 38, the fuel increase pump 16 can be operated using the air-fuel mixture 13 in the air-fuel mixture supply flow path 36.
Thereby, in order to operate the fuel increase pump 16, since it is not necessary to provide an air flow path in the insulator part 15 unlike the prior art, it is possible to reduce the size.

Furthermore, since it is not necessary to provide an air flow path in the insulator portion 15, the negative pressure chamber flow path 38 can be provided in the vicinity of the air-fuel mixture supply flow path 36.
Therefore, the shape of the negative pressure chamber channel 38 can be simplified to a straight line, and the overall length (L1 + L2) can be kept small. L2 is illustrated in FIG.

Thereby, the air-fuel mixture 13 can be smoothly guided to the negative pressure chamber 65 through the negative pressure chamber flow path 38 in a short time, and the timing for guiding the air-fuel mixture 13 to the negative pressure chamber 65 can be ensured satisfactorily.
Therefore, the fuel 12 in the fuel storage chamber 26 can be derived with an increased amount of response in response to the operation of the throttle valve 23 shown in FIG.

Returning to FIG. 1 again, the fuel increase pump 16 is incorporated in the insulator portion 15 and is disposed above the air-fuel mixture supply flow path 36.
Specifically, as shown in FIGS. 2 and 4, the fuel booster pump 16 is disposed above in a state that is laterally offset with respect to the mixing channel 22 and the mixture supply channel 36 of the vaporizer 11. Has been.

  The fuel increase pump 16 includes a storage unit 45 formed integrally with the insulator unit 15, a pump main body 51 stored in the storage unit 45, and a lid 52 that holds the pump main body 51 in the storage unit 45. ing.

The storage part 45 has a lower part 45 a formed substantially horizontally, and the pump body 51 is stored in the storage part 45.
In the pump body 51, a compression spring 56 is interposed between the support member 54 and the moving member 55, and the moving member 55 is pressed against the negative pressure diaphragm 57 by the spring force of the compression spring 56.

The flange portion 57 a of the negative pressure diaphragm 57 and the flange portion 54 a of the support member 54 are sandwiched between the outer peripheral edge 45 b of the storage portion 45 and the outer peripheral edge 52 a of the lid 52.
The support member 54 has a discharge hole 61 formed in the lower portion 54b. The discharge hole 61 is a hole facing the lower part 45 a of the storage unit 45.
The lid 52 is attached to the outer peripheral edge 45b of the storage portion 45 with screws 63 and 63 (see FIGS. 2 and 4).

A negative pressure chamber 65 is formed by the storage portion 45 and the negative pressure diaphragm 57. The negative pressure chamber 65 is adjacent to the pump chamber 66 via a negative pressure diaphragm 57.
The pump chamber 66 is formed of a negative pressure diaphragm 57 and a lid 52.
The pump chamber 66 is a chamber in which the space 46 decreases as the negative pressure diaphragm 57 moves to the lid 52 side.
By reducing the space 46 in the pump chamber 66, it is possible to guide the air in the pump chamber 66 to the pressurizing chamber 27 through the pump chamber flow path 31 and pressurize the pressurizing chamber 27.

The lid 52 is formed with a pressurizing hole 71 that communicates with the pump chamber 66 and an air opening hole 72 that opens to the atmosphere.
The pressurizing hole 71 communicates with the pressurizing chamber 27 through the pump chamber flow path 31.
The air release hole 72 is a hole that communicates the pump chamber 66 with the atmosphere.

FIG. 5 is a perspective view showing a state in which the insulator portion of the fuel supply apparatus for an engine according to the present invention is disassembled, and FIG. 6 is a sectional view taken along line 6-6 of FIG.
The pump chamber flow path 31 described above includes first to third pump chamber flow paths 75 to 77 formed integrally with the body 21 so as to communicate the pump chamber 66 and the pressurization chamber 27.

The first pump chamber flow path 75 is a flow path that is formed substantially parallel to the mixing flow path 22 and communicates with the pressurizing hole 71 of the lid 52.
The second pump chamber flow path 76 is a flow path that is formed so as to intersect the mixing flow path 22 at a substantially right angle from the end of the first pump chamber flow path 75 toward the vaporizer-side pump 29. is there.
The third pump chamber channel 77 is a channel formed from the end of the second pump chamber channel 76 to the pressurizing chamber 27 substantially parallel to the mixing channel 22.

By connecting the first pump chamber channel 75 to the pressurizing hole 71 and the third pump chamber channel 77 to the pressurizing chamber 27, the pump chamber 66 and the pressurizing chamber 27 are connected to the pump chamber channel 31. The pressure holes 71 communicate with each other.
Therefore, the air in the pump chamber 66 can be introduced into the pressurizing chamber 27 via the pressurizing hole 71 and the pump chamber flow path 31.

By forming the pump chamber flow path 31 integrally with the body 21, it is not necessary to provide the pump chamber flow path 31 with an individual member (for example, a hose or a tube).
Therefore, the number of parts can be reduced to simplify the configuration, and the number of assembly steps can be reduced.

Further, as shown in FIG. 2, a carburetor-side pump 29 is provided in the side portion 11 a on the fuel increase pump 16 side in the carburetor 11.
Therefore, the pressurizing hole 71 of the carburetor-side pump 29 can be disposed in the vicinity of the fuel increase pump 16.
As a result, the shape of the pump chamber flow path 31 can be simplified and the overall length can be kept small, and the air in the pump chamber 66 can be quickly sent to the pressurizing chamber 27.

Next, the operation of the fuel supply apparatus 10 for the engine will be described based on the principle diagrams of FIGS.
First, the operation when the fuel supply device 10 of the engine is suddenly accelerated from the idling state will be described based on the principle diagrams of FIGS.
FIG. 7 is a view for explaining an operation example when the fuel supply device for an engine according to the present invention is accelerated rapidly from an idling state.
In the idling state of the engine 14, the opening degree of the throttle valve 23 is increased and the engine 14 is accelerated rapidly.
A large amount of air is instantaneously guided to the mixing channel 22 of the vaporizer 11 as indicated by an arrow A.

The fuel 12 in the fuel storage chamber 26 is supplied to the venturi section 24 through the fuel nozzle 25 as shown by an arrow B.
Fuel 12 is mixed with a large amount of air to form an air-fuel mixture 13. The air-fuel mixture 13 is instantaneously guided to the air-fuel mixture supply flow path 36 as indicated by an arrow C.

A part of the introduced large amount of air-fuel mixture 13 is instantaneously guided to the negative pressure chamber 65 of the fuel booster pump 16 through the negative pressure chamber flow path 38 as indicated by an arrow D.
Here, the negative pressure chamber flow path 38 extends upward from the mixture supply flow path 36 toward the negative pressure chamber 65.

Specifically, as shown in FIG. 4, the first negative pressure chamber flow path 41 of the negative pressure chamber flow path 38 is straight upward at an inclination angle θ from the mixture supply flow path 36 toward the negative pressure chamber 65. It is extended to the shape.
The air-fuel mixture 13 smoothly flows through the negative pressure chamber channel 38 by extending the negative pressure chamber channel 38 (specifically, the first negative pressure chamber channel 41) linearly. Therefore, the air-fuel mixture 13 can be quickly guided from the negative pressure chamber flow path 38 to the negative pressure chamber 65.

A large amount of the air-fuel mixture 13 that is instantaneously guided to the negative pressure chamber 65 presses the moving member 55 as indicated by an arrow E. The negative pressure diaphragm 57 moves to the lid 52 side, and the space 46 of the pump chamber 66 decreases.
By reducing the space 46 in the pump chamber 66, the air in the pump chamber 66 is pushed out to the pressurizing chamber 27 through the pressurizing hole 71 and the pump chamber flow path 31 as indicated by an arrow F.
The air is pushed into the pressurizing chamber 27 to pressurize the pressurizing chamber 27, and the pressurizing diaphragm 28 moves to the fuel storage chamber 26 side as indicated by an arrow G.

FIG. 8 is a view for explaining an example of temporarily increasing the amount of fuel in the engine fuel supply apparatus according to the present invention.
When the pressurizing diaphragm 28 moves to the fuel storage chamber 26 side, the fuel 12 in the fuel storage chamber 26 is supplied to the venturi portion 24 through the fuel nozzle 25 and temporarily supplied as shown by an arrow H.

Therefore, the amount of the fuel 12 contained in the air-fuel mixture 13 can be temporarily increased to flow in the air-fuel mixture supply flow path 36 as indicated by the arrow I.
Thereby, the air-fuel mixture 13 in which the amount of fuel 12 is temporarily increased can be guided to the engine 14, and the engine 14 can be prevented from being poorly accelerated or stopped.

By the way, when the throttle valve 23 is maintained at a constant opening, the air-fuel mixture supply passage 36 is in a negative pressure state. When the air-fuel mixture supply flow path 36 is in a negative pressure state, the negative pressure chamber 65 of the fuel increase pump 16 becomes negative pressure.
Therefore, the negative pressure diaphragm 57 moves toward the support member 54 as indicated by the arrow J, and the air in the pump chamber 66 is not pumped to the pressurizing chamber 27.
As a result, the engine 14 is driven in a normal state where the fuel 12 contained in the air-fuel mixture 13 is not temporarily increased.

Next, the operation of returning the fuel in the fuel increase pump of the fuel supply device 10 of the engine to the mixture supply passage 36 will be described based on the principle diagram of FIG.
FIG. 9 is a view for explaining an example in which the fuel in the fuel increase pump of the engine fuel supply apparatus according to the present invention is returned to the mixture supply passage.
As described with reference to FIG. 7, when the throttle valve 23 is increased in opening and suddenly accelerated, a part of the air-fuel mixture 13 is guided to the negative pressure chamber 65 of the fuel booster pump 16.

For this reason, the fuel 12 contained in the air-fuel mixture 13 accumulates in the lower portion 45 a of the negative pressure chamber 65 and the inside of the support member 54.
It is conceivable that the air-fuel ratio of the air-fuel mixture 13 supplied from the carburetor 11 to the engine varies due to the fuel 12 remaining in the negative pressure chamber 65.
When the air-fuel ratio of the air-fuel mixture 13 fluctuates, it is difficult to drive the engine 14 smoothly.

Therefore, the fuel increase pump 16 is disposed above the mixture supply passage 36.
Specifically, as shown in FIG. 2, the fuel increase pump 16 is disposed on the upper side in a state offset to the side of the mixing flow path 22 of the vaporizer 11, that is, on the side portion 11 a side.
Then, the negative pressure chamber flow path 38 was extended from the lower portion 45 a of the negative pressure chamber 65 toward the mixture supply flow path 36.

Therefore, as shown in FIG. 4, the first negative pressure chamber channel 41 of the negative pressure chamber channel 38 is extended downward from the negative pressure chamber 65 side toward the mixture supply channel 36 at an inclination angle θ. Yes.
As a result, when the air-fuel mixture 13 is guided to the negative pressure chamber 65 and the fuel 12 is dripped into the lower portion 45a of the negative pressure chamber 65, the air-fuel mixture supply flow path 36 passes through the negative pressure chamber flow path 38 as indicated by the arrow K. Can be returned.

Further, the fuel 12 dripped inside the support member 54 is guided to the lower portion 45 a from the discharge hole 61 of the support member 54. As described above, the fuel 12 guided to the lower portion 45a can be returned to the air-fuel mixture supply flow path 36 through the negative pressure chamber flow path 38 as indicated by an arrow K.
Thereby, it is possible to smoothly drive the engine 14 while suppressing the air-fuel ratio of the air-fuel mixture 13 from fluctuating.

Here, the negative pressure chamber flow path 38 extends downward from the negative pressure chamber 65 toward the mixture supply flow path 36.
Specifically, as shown in FIG. 4, the first negative pressure chamber flow path 41 of the negative pressure chamber flow path 38 extends linearly from the negative pressure chamber 65 side toward the mixture supply flow path 36. ing.
As described above, the negative pressure chamber flow path 38 (specifically, the first negative pressure chamber flow path 41) is linearly extended, so that the fuel in the negative pressure chamber 65 passes through the negative pressure chamber flow path 38. It is possible to smoothly return to the air-fuel mixture supply flow path 36.

  In addition, although the example which uses the fuel supply apparatus 10 of an engine for liquid fuel was demonstrated in the said embodiment, it is not restricted to this, It can also be used for gaseous fuel.

  In the above-described embodiment, the example in which the fuel increase pump 16 is offset to the side portion 11a side with respect to the mixing flow path 22 and disposed above is described. However, the fuel increase pump 16 is disposed with respect to the mixing flow path 22. It is also possible to dispose it upward without offset.

  Further, in the above-described embodiment, the example in which the first negative pressure chamber flow path 41 is extended at the inclination angle θ has been described. However, the present invention is not limited to this, and the first negative pressure chamber flow path 41 may be extended right above. Is possible.

  Moreover, in the said embodiment, although the example which extended the 1st negative pressure chamber flow path 41 linearly was demonstrated, it is not restricted to this, For example, the 1st negative pressure chamber flow path 41 is convex downward. It is also possible to form it in a substantially square shape.

  INDUSTRIAL APPLICABILITY The present invention is suitable for application to a fuel supply device for an engine provided with a fuel increase pump that increases the amount of fuel led to the carburetor.

1 is a principle diagram showing a fuel supply device for an engine according to the present invention. It is a side view of the fuel supply apparatus of the engine which concerns on this invention. It is a perspective view which shows the state which decomposed | disassembled the plate from the insulator part of the fuel supply apparatus of the engine which concerns on this invention. FIG. 4 is a view taken in the direction of arrow 4 in FIG. 3. It is a perspective view which shows the state which decomposed | disassembled the insulator part of the fuel supply apparatus of the engine which concerns on this invention. FIG. 6 is a sectional view taken along line 6-6 of FIG. It is a figure explaining the example of an operation when the fuel supply device of the engine concerning the present invention is accelerated rapidly from the idling state. It is a figure explaining the example which makes fuel increase temporarily with the fuel supply apparatus of the engine which concerns on this invention. It is a figure explaining the example which returns the fuel in the fuel increase pump of the fuel supply apparatus of the engine which concerns on this invention to an air-fuel mixture supply flow path.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Engine fuel supply device, 11 ... Vaporizer, 12 ... Fuel, 13 ... Mixture, 14 ... Engine, 15 ... Insulator part, 16 ... Fuel increase pump, 21 ... Body (main body), 26 ... Fuel chamber, 27 DESCRIPTION OF SYMBOLS ... Pressure chamber, 28 ... Pressure diaphragm, 36 ... Mixture supply flow path, 38 ... Negative pressure chamber flow path, 41 ... 1st negative pressure chamber flow path, 42 ... 2nd negative pressure chamber flow path, 45a ... Lower part 57 ... Negative pressure diaphragm, 65 ... Negative pressure chamber, 66 ... Pump chamber.

Claims (1)

Pressure diaphragm partitioning the fuel chamber and the pressurizing chamber in the carburetor is provided in the fuel supply system for an engine which increase the amount of fuel derived from the fuel chamber by pressurizing the pressure chamber,
An air- fuel mixture mixed with the fuel in the carburetor is provided to the engine without providing an air flow path that is interposed between the carburetor and the engine to insulate heat of the engine and guide air to the engine. An insulator portion provided with an air-fuel mixture supply flow path;
A pump chamber that is incorporated in the insulator unit and disposed above the air-fuel mixture supply flow path and pressurizes the pressurizing chamber is provided, and a negative pressure chamber is adjacent to the pump chamber via a negative pressure diaphragm. A fuel booster pump,
A negative pressure chamber channel that extends downward from the lower part of the negative pressure chamber toward the mixture supply channel, and introduces a part of the mixture into the negative pressure chamber from the mixture supply channel;
Bei to give a,
The negative pressure chamber flow path includes a first negative pressure chamber flow path formed substantially perpendicular to the air-fuel mixture supply flow path, and the air-fuel mixture supply through the first negative pressure chamber flow path and the negative pressure chamber. A second negative pressure chamber flow channel formed substantially parallel to the flow channel, and the first negative pressure chamber flow channel and the second negative pressure chamber flow channel are formed integrally with the insulator portion. An engine fuel supply device.

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