JP3533310B2 - Engine fuel supply - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine fuel supply system.

[0002]

2. Description of the Related Art A conventional fuel supply device for an engine is shown in FIG. This is similar to the present invention, in which the venturi passage 103 is internally provided in the mixing body 102 of the carburetor 101, the float chamber 104 is attached to the mixing body 102, and the liquid fuel nozzle 105 is communicated with the float chamber 104, and the liquid fuel nozzle outlet is provided. The Venturi passage 103 is faced with 106.

In this conventional technique, a gas mixer 134 is connected in series on the intake upstream side of the carburetor 101, a gas fuel nozzle 107 is provided in this gas mixer 134, and a gas fuel nozzle outlet 108 is made to face a venturi passage 135 of the gas mixer 134. The supply of liquid fuel and gas fuel can be switched.

[0004]

The above-mentioned prior art has the following problems. Since the venturi passage 103 of the carburetor 101 and the venturi passage 135 of the gas mixer 134 are connected in series, the intake resistance increases due to the two-stage throttling resistance, the intake charging efficiency decreases, and the output decreases. A gas mixer 134 is provided on the intake upstream side of the carburetor 101.
Is located, the turbulence occurs in the intake flow introduced into the venturi passage 103 of the carburetor 101, and the accuracy of liquid fuel metering decreases. Since the carburetor 101 and the gas mixer 134 are used, the device becomes large.

The problems of the present invention are as follows. To get high output. Increase the accuracy of liquid fuel metering.
Miniaturize the device.

[0006]

[Means for Solving the Problems]

(First Invention) As shown in FIG. 1, a first invention is such that a venturi passage 3 is internally provided in a mixing body 2 of a carburetor 1, a float chamber 4 is attached to the mixing body 2, and a liquid fuel nozzle is provided in the float chamber 4. The fuel supply device for an engine in which the liquid fuel nozzle outlet 6 faces the venturi passage 3 is characterized by the following.

A gas fuel nozzle 7 is provided in the mixing body 2, and the liquid fuel nozzle outlet 6 and the gas fuel nozzle outlet 8 face the same venturi passage 3 so that the supply of the liquid fuel and the gas fuel can be switched. And then
As shown in FIG. 3, a gas fuel valve 33 for shutting off the supply of the gas fuel to the gas fuel nozzle 7 is provided downstream of the regulator 32.
When the fuel switching means 26 is in the liquid fuel supply state, the gas fuel valve 33 is closed, the fuel switching means 26 is in the gas fuel supply state, and the choke valve 27 has a predetermined opening degree. When the position is the fully open side position equal to or more than the value, the gas fuel valve 33 is opened, and the choke valve 27 is fully closed with the opening less than the predetermined value even when the fuel switching means 26 is in the gas fuel supply state. When the vehicle is in the side posture, the gas fuel valve 33 is closed.

(Second Invention) The second invention is shown in FIG. 3 or FIG.
As shown in, in the first invention, a gas fuel valve 33,
An opening detecting means 59 for detecting the opening of the choke valve 27 is attached to the mixing body 2.

[0009]

[Operation and effect of the invention]

(First Invention) The first invention has the following effects (see FIG. 1 or 3). Since no gas mixer is required, the intake resistance can be reduced, the filling efficiency can be increased, and high output can be obtained. Since it is not necessary to provide a gas mixer on the upstream side of the intake of the carburetor 1, the intake flow passing through the venturi passage 3 of the carburetor 1 is less likely to be disturbed, and the liquid fuel metering accuracy can be improved. Since the gas mixer is unnecessary, the device can be downsized.

Since the gas fuel valve 33 is provided downstream of the regulator 32, when the gas fuel is switched to the liquid fuel, a small amount of gas fuel remaining downstream of the gas fuel valve 33 is sucked into the venturi passage 3. The gas fuel is not sucked into the venturi passage 3. For this reason,
After switching to the liquid fuel, the mixture concentration of the liquid fuel is optimized in a short time, and the deterioration of the operating state and the exhaust gas characteristics can be suppressed.

When the fuel switching means 26 is in the liquid fuel supply state, the gas fuel valve 33 downstream of the regulator 32 is closed, so that the choke valve 27 is almost fully closed when starting the engine with the liquid fuel. Even if it is set, the large negative pressure generated in the venturi passage 3 still remains in the regulator 3
It is possible to prevent damage to the diaphragm or the like in the regulator 32, which is less than that of 2.

When the engine start by the gas fuel is inappropriate, that is, when the choke valve 27 is in the fully closed position with the opening less than the predetermined value, the gas fuel valve 33 is closed, so that the engine cannot be started. If the engine is started with the gas fuel with the choke valve 27 in the fully closed side posture, the mixture of the gas fuel may become too rich and the exhaust gas characteristics may deteriorate. However, in the present invention, the choke valve 27 is fully closed. In the case of the side posture, the gas fuel valve 33 is closed and the engine cannot be started, so that it is possible to prevent the deterioration of the exhaust gas characteristics and to inform the user that the posture of the choke valve 27 is inappropriate. Can inform.

(Second Invention) The second invention has the following effects in addition to the effects of the first invention (see FIG. 3 or FIG. 5). Since the gas fuel valve 33 and the opening degree detection means 59 are attached to the mixing body 2, it is difficult to forget to attach them.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to the drawings. 1 to 5 are views for explaining a spark ignition type engine according to the first embodiment of the present invention. The structure of this engine is as follows. That is, as shown in FIG. 5, the cylinder head 51 is provided above the cylinder block 50.
The timing transmission case 53 is attached to the front side of the cylinder block 50 and the cylinder head 51, with the direction of the crankshaft axis 52 as the front-rear direction. A valve operating cam case 54 is attached to the side of the cylinder block 50, and the front side of the valve operating cam case 54 is connected to the timing transmission case 53. An intake manifold 5 is provided on the side of the cylinder head 51.
5 is assembled and the carburetor 1 is attached to the rear part.

The structure of the carburetor 1 is as follows.
As shown in FIG. 1, a venturi passage 3 is provided in a mixing body 2 of a carburetor 1, a float chamber 4 is attached to the mixing body 2, a liquid fuel nozzle 5 is connected to the float chamber 4, and a liquid fuel nozzle outlet 6 is provided. Is facing the Venturi passage 3.

The float chamber 4 is disposed below the mixing body 2 and accommodates the float 36 therein.
The liquid fuel supply port 40 to the float chamber 4 is opened and closed by a needle valve 37 attached to the. The mixing body 2 is provided with an air vent 42, and the mixing body 2
An air vent 42 connects the intake passage (outside the drawing) on the intake upstream side with the float chamber 4.

A nozzle accommodating boss 41 is vertically provided from the mixing body 2 into the float chamber 4.
The liquid fuel nozzle 5 is fitted inside, and the upper end portion of the liquid fuel nozzle 5 is projected into the venturi passage 3. A liquid fuel metering jet 56 is arranged below the liquid fuel nozzle 5. The liquid fuel inlet 13 is provided at the inner bottom of the fuel float chamber 4.
The liquid fuel inlet 13 connects the float chamber 4 and the liquid fuel nozzle 5. A liquid fuel valve 14 for opening and closing the liquid fuel inlet 13 is laterally arranged at the lower portion of the float chamber 4. As shown in FIG. 2, a choke valve 27 is arranged on the intake upstream side of the venturi passage 3, and a throttle valve 22 is arranged on the intake downstream side.

In this embodiment, in order to obtain a high output, the following is done. As shown in FIG. 1, a gas fuel nozzle 7 is provided in the mixing body 2, and a liquid fuel nozzle outlet 6 is provided.
The gas fuel nozzle outlet 8 faces the same venturi passage 3 so that the supply of liquid fuel and gas fuel can be switched. In this case, since the gas mixer is not needed, the intake resistance can be reduced, the filling efficiency can be increased, and a high output can be obtained. Further, since it is not necessary to provide a gas mixer on the intake upstream side of the carburetor 1, turbulence hardly occurs in the intake air flow passing through the venturi passage 3 of the carburetor 1, and the liquid fuel metering accuracy can be increased. Further, since the gas mixer is not necessary, the device can be downsized.

In this embodiment, as shown in FIG. 3, in order to supply the liquid fuel from the liquid fuel supply source 16 to the float chamber 4, a liquid fuel supply passage 43 is provided, and the liquid fuel supply passage 43 is supplied with the liquid fuel. A liquid fuel cock 44, a liquid fuel filter 45, and an electric liquid fuel pump 15 are arranged in this order from the source 16 side. Further, in order to supply the gas fuel from the gas fuel supply source 31 to the carburetor 1, a gas fuel supply path 39 is provided, and in the gas fuel supply path 39 from the gas fuel supply source 31 side, the gas fuel filter 46 and the electromagnetic type. An upstream gas fuel valve 47, a regulator 32, and an electromagnetic downstream gas fuel valve 33 are arranged. Regulator 3
2 also serves as a vaporizer, so that the vaporization of gas fuel can be promoted inside.

In this embodiment, in order to switch the supply of the gas fuel and the liquid fuel, as shown in FIG. 3, the fuel switching means 26 is connected to the ON position 49 of the key switch 28, and the liquid switching means 26 is connected to the liquid switching means 26. The fuel valve 14 and the two gas fuel valves 47 and 33 are linked. And
When the fuel switching means 26 is in the gas fuel supply state and the key switch 28 is in the engine starting position 29 or the ON position 49, the two gas fuel valves 47 and 33 maintain the open state by energization, Gas fuel is supplied to the venturi passage 3. At this time, the liquid fuel valve 14 is de-energized to maintain the valve closed state, and the liquid fuel is not supplied to the venturi passage 3.

On the other hand, when the fuel switching means 26 is in the liquid fuel supply state and the key switch 28 is in the engine starting position 29 or the ON position 49, the liquid fuel valve 14
Is kept open by energization, and liquid fuel is supplied to the venturi passage 3. At this time, the two gas fuel valves 47 and 33 are de-energized to maintain the closed state,
No gas fuel is supplied to the venturi passage 3.
The ignition device 63 is provided at the ON position 49 of the key switch 28.
When the key switch 28 is placed in the ON position 49 or the engine starting position 29, the ignition device 63 is activated.

In this embodiment, in order to improve the accuracy of gas fuel metering, as shown in FIG. 2, the gas is introduced into a passage portion having an inner diameter 10 larger than the inner diameter 9 of the passage portion facing the liquid fuel nozzle outlet 6. The fuel nozzle outlet 8 is exposed. With this configuration, the negative pressure generated in the passage portion facing the gas fuel nozzle outlet 8 is smaller than the negative pressure generated in the passage portion facing the liquid fuel nozzle outlet 6, so that suction of gas fuel having a small mass is performed. The gas fuel can be metered with high accuracy.

Further, as shown in FIG. 2, since the gas fuel nozzle outlet 8 is arranged on the intake upstream side of the liquid fuel nozzle outlet 6, the liquid fuel sucked from the liquid fuel nozzle 5 into the venturi passage 3 is in the intake direction. Good side gas fuel nozzle 7
It is hard to enter inside.

In this embodiment, the gas fuel is supplied to the gas fuel nozzle 7 downstream of the regulator 32 in order to optimize the mixture concentration of the liquid fuel in a short time after switching to the liquid fuel. A gas fuel valve 33 for shutting off is provided, and the gas fuel valve 33 is closed when the fuel switching means 26 is in the liquid fuel supply state.

According to such a configuration, the gas fuel valve 33
Is provided downstream of the regulator 32, so that when the gas fuel is switched to the liquid fuel, after the small amount of gas fuel remaining downstream from the gas fuel valve 33 is sucked into the venturi passage 3, Not sucked into 3. Therefore, the mixture concentration of the liquid fuel is optimized in a short time after switching to the liquid fuel, and the deterioration of the operating state and the exhaust gas characteristic can be suppressed.

Further, when the fuel switching means 26 is in the liquid fuel supply state, the gas fuel valve 33 on the downstream side of the regulator 32 is closed, so that the choke valve 27 is operated when the engine is started with the liquid fuel. Even when it is close to the fully closed state, the large negative pressure generated in the venturi passage 3 does not reach the regulator 32, and the diaphragm and the like in the regulator 32 can be prevented from being damaged.

In this embodiment, the gas fuel supply passage 39
In order to prevent the liquid fuel from being accumulated therein, the gas fuel nozzle 7 is directed downward toward the venturi passage 3, and the gas fuel introduction passage 11 for introducing the gas fuel from the regulator 32 to the gas fuel supply nozzle 7 is provided in the mixing body 2. An expansion chamber 12 having a larger passage cross-sectional area than the gas fuel nozzle 7 is provided above the gas fuel nozzle 7.
The gas fuel supply passage 11 and the gas fuel nozzle 7 are communicated with each other via the valve, and the valve seat 33a of the gas fuel valve 33 is arranged at the passage outlet 11a of the gas fuel supply passage 11 facing the expansion chamber 12.

According to such a configuration, since the expansion chamber 12 is provided above the gas fuel nozzle 7, even if the intake air containing the liquid fuel enters the gas fuel nozzle 7 during the supply of the liquid fuel, this intake air The flow velocity of the liquid drops in the expansion chamber 12, and the large liquid drops fall under its own weight. Then, the dropped droplets return from the downward gas fuel nozzle 7 to the venturi passage 3. Further, the valve seat 33a of the gas fuel valve 33 has the gas fuel introduction passage 1
Since it is arranged at the first passage outlet 11a, the liquid fuel does not enter the gas fuel introduction passage 11.

Therefore, during the supply of the liquid fuel, the liquid fuel hardly accumulates in the gas fuel supply passage 39. When the liquid fuel is accumulated in the gas fuel supply passage 39, when the supply of the gas fuel is started, the liquid fuel is pushed out from the gas fuel supply passage 39 into the venturi passage 3 and flows into the combustion chamber in a liquid state to cause misfire. It may happen. In this embodiment, almost no liquid fuel is accumulated in the gas fuel supply passage 39, so that such misfire can be prevented.

In this embodiment, since the gas fuel valve 33 is compactly mounted on the carburetor 1, the gas fuel valve 3
3 is composed of a linear actuator 33b, a valve body 33d attached to the tip of an output rod 33c of the linear actuator 33b, and the valve seat 33a. The linear actuator 33b reciprocates the valve body 33d in the expansion chamber 12. As a result, the gas fuel valve 33 is opened and closed. With such a configuration, the expansion chamber 12 can be effectively used as a valve chamber, so that the gas fuel valve 33 can be compactly mounted on the carburetor 1.

In this embodiment, the gas fuel introduction passage 11 and the gas fuel nozzle 7 are connected in a bent shape through the expansion chamber 12. By doing so, since the expansion chamber 12 is located at the connection point between the gas fuel introduction passage 11 and the gas fuel nozzle 7 that are connected in a bent shape, the passage resistance at the bent portion can be reduced and the gas fuel can pass smoothly. As a result, the accuracy of gas fuel metering is improved.

In this embodiment, in order to prevent the operating condition and the exhaust gas characteristics from deteriorating at the time of switching to the gas fuel, the following is done. As shown in FIG. 1, a liquid fuel inlet 13 is provided between the float chamber 4 and the liquid fuel nozzle 5, and a liquid fuel valve 14 for opening and closing the liquid fuel inlet 13 is provided. Is opened, and the liquid fuel valve 14 is closed while the gas fuel is being supplied. With this configuration, when the liquid fuel is switched to the gas fuel, the liquid fuel may be sucked into the venturi passage 3 after the small amount of the liquid fuel remaining in the liquid fuel nozzle 5 is sucked into the venturi passage 3. Since there is no gas fuel, the gas-fuel mixture concentration is optimized in a short time after switching to gas fuel, and it is possible to suppress deterioration of operating conditions and exhaust gas characteristics.

In this embodiment, in order to prevent the needle valve 37 of the float 36 from being worn, the following is done. As shown in FIG. 3, the liquid fuel pump 15 is operated even during the gas fuel supply to supply the liquid fuel of the liquid fuel supply source 16 to the float chamber 4 of the carburetor 1. In this way, as shown in FIG. 1, even if the liquid fuel in the float chamber 4 evaporates and flows out from the air vent 42 or the like during the gas fuel supply, the liquid fuel pump 15 replenishes the float chamber 4 with the liquid fuel. Therefore, the float chamber 4 does not become empty. When the float chamber 4 becomes empty, the vibration of the engine causes the float 36 to move up and down violently, causing the float 3 to move.
No. 6 needle valve 37 is damaged, but in this embodiment,
Since the float chamber 4 is never empty, the float 36
The needle valve 37 can be prevented from being damaged. Since the liquid fuel pump 15 is directly connected to the ON position 49 of the key switch 28 without passing through the fuel switching means 26, the liquid fuel pump 15 operates even during the gas fuel supply.

In this embodiment, in order to smoothly start the engine with the gas fuel, the following is done. As shown in FIG. 4, a valve opening setting lever 17 is provided outside the mixing body 2, and the valve opening setting lever 17 is provided.
A receiving portion 18 is provided in the valve opening setting lever 17 so that the valve opening setting lever 17 can be switched between a gas starting setting attitude 19 and a gas starting releasing attitude 20, and the valve opening setting lever 17 is switched to a gas starting setting attitude 19. , Its receiving part 1
When the throttle input lever 21 is received at 8, the throttle valve 22 takes the gas starting suitability posture 24 with a predetermined opening 23, while the valve opening setting lever 17 is moved to the gas starting releasing posture 2
When it is switched to 0, the receiving portion 18 is retracted to a position where it does not interfere with the throttle input lever 21.

In this way, the throttle valve 22 can be brought into the gas starting suitability posture 24 with the predetermined opening 23 when the engine is started by the gas fuel. If the opening degree of the throttle valve 22 is too small when the engine is started by gas fuel, the amount of the air-fuel mixture supplied to the combustion chamber becomes insufficient, while if the opening degree of the throttle valve 22 is too large, it is supplied to the combustion chamber. There is a case where the concentration of the air-fuel mixture becomes too thin and the engine cannot be started smoothly. However, in this embodiment, the throttle valve 22 can be placed in the gas start suitable posture 24, so that the engine can be started by gas fuel. It can be done smoothly.

Further, when the engine start by the gas fuel is completed and the valve opening setting lever 17 is switched to the gas start release posture 20, the receiving portion 18 causes the throttle input lever 2 to move.
The valve opening setting lever 17 does not interfere with the interlocking of the throttle valve 22 during the normal operation with gas fuel, the engine start with liquid fuel, and the normal operation, because the valve retracts to a position where it does not buffer with 1. That is, the throttle valve 22
Can be opened and closed over the entire range.

In this embodiment, the receiving portion 18 receives the throttle input lever 21 which is about to rotate in the fully open direction of the throttle valve 22. When the speed adjusting operation means 64 is operated to the high speed side, the mechanical governor 65
The throttle input lever 21 is urged toward the fully opening direction of the throttle valve 22 by the spring force 62 of the governor spring 61. Further, the opening degree 23 of the throttle valve 22 that is in the gas starting suitability posture 24 is set according to the engine for which the carburetor 1 is suitable. In this embodiment, the opening of the throttle valve 22 in the fully closed position is 0 °, the opening in the fully opened position is 90 °, and the opening 23 is set to 30 °.

In this embodiment, in order to start the engine with gas fuel by a simple operation, the following is done. As shown in FIG. 3, the valve opening setting lever 17
Is linked to an electric actuator 25, the fuel switching means 26 is in a gas fuel supply state, and when the key switch 28 is turned on to the engine starting position 29, the starter 30 operates and the actuator 25 operates. The valve opening setting lever 17 to the gas start setting posture 1
It is linked to 9. With this configuration, the starter 30 and the actuator 25 can be operated only by inserting the key switch 28 into the engine starting position 29, so that the engine starting operation using gas fuel can be easily performed.

In this embodiment, when the key switch 28 is moved from the engine starting position 29 to the ON position 49, the starter 30 is stopped, and after a predetermined set time has elapsed, the valve opening setting lever 17 of the actuator 25 is moved to the gas start releasing posture 20. Returned to.

As shown in FIG. 3, the fuel switching means 26
The engine start position 29 of the key switch 28 is linked to the starter 30 and the actuator 25 through the control means 60, and the above control is performed. A microcomputer is used as the control means 60.

In this embodiment, in order to prevent the engine starting from being performed when the engine starting by the gas fuel is inappropriate, the following is done. As shown in FIG. 3, when the fuel switching means 26 is in the gas fuel supply state and the choke valve 27 is in the fully open side posture with a predetermined opening or more, the gas fuel valve 33 is opened. Even when the fuel switching means 26 is in the gas fuel supply state, the gas fuel valve 33 is closed when the choke valve 27 is in the fully closed position with the opening less than the predetermined value. The larger the numerical value of the opening of the choke valve 27, the closer it becomes to full opening.

According to this structure, when the engine start by gas fuel is inappropriate, that is, the choke valve 27.
Is in the fully closed position with the opening less than the predetermined value, the gas fuel valve 33
Is closed, the engine cannot be started. When the engine is started with the gas fuel with the choke valve 27 in the fully closed position, the mixture of the gas fuel may become too rich and the exhaust gas characteristics may deteriorate. However, in this embodiment, the choke valve 27 is completely closed. In the closed posture, the engine does not start, so deterioration of exhaust gas characteristics can be prevented, and the user can be notified that the posture of the choke valve 27 is inappropriate.

As shown in FIG. 3, the choke valve 27 is interlockingly connected to the choke operating tool 58 via the push-pull wire 57, and the pushing arm 68 is attached to the input arm 67 of the choke valve 27.
The opening of the choke valve 27 is equal to or more than a predetermined value depending on whether the pressing piece 68 contacts the opening detecting means 59. It is possible to detect whether it is less than a predetermined value. And
A relay 69 is provided in the fuel switching means 26, the relay 69 is made to cooperate with the opening degree detecting means 59, and when the opening degree detecting means 59 detects that the opening degree of the choke valve 27 is less than a predetermined value, the relay 69 Is turned off and the gas switching valve 59 is in the gas fuel supply state, the gas fuel valve 47.
The 33 is not energized, and these keep the valve closed state.

In this embodiment, the gas fuel valve 33 and the opening detecting means 59 for detecting the opening of the choke valve 27 are mounted on the mixing body 2. In this way, since the gas fuel valve 33 and the opening degree detection means 59 are attached to the carburetor 1, it is difficult to forget to attach them.

In this embodiment, in order to smoothly start the engine with the liquid fuel, as shown in FIG.
When the fuel switch means 26 is in the liquid fuel supply state, when the key switch 28 is turned to the engine starting position 29, the starter 30 operates but the actuator 25 does not operate, and the valve opening degree setting lever. 17 maintains the gas start release posture 20.

In this way, as shown in FIG. 4, when the engine is started with the liquid fuel, the valve opening setting lever 1
Since 7 is maintained in the gas start releasing posture 20, the supply of the liquid fuel mixture to the combustion chamber is not hindered by the restriction of the opening degree of the throttle valve 22, and the engine can be smoothly started by the liquid fuel. You can Such control is performed by the control means 60.

The second embodiment shown in FIG. 6 is a gas fuel valve 3
It has the same structure as the first embodiment except that the shape of 3 is different. In FIG. 6, the same elements as those in the first embodiment are designated by the same reference numerals.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a carburetor used in an engine according to a first embodiment.

FIG. 2 is a sectional view taken along line II-II in FIG.

FIG. 3 is a perspective view of a fuel supply device used in the engine of the first embodiment.

FIG. 4 is a plan view of a main part of a carburetor used in the engine of the first embodiment, FIG. 4 (A) showing a valve opening setting lever in a gas start setting posture, and FIG. 4 (B) showing a valve opening. It is a figure in which a degree setting lever is in a gas start release posture.

FIG. 5 is a plan view of a main part of the engine according to the first embodiment.

FIG. 6 is a view corresponding to FIG. 1 of the second embodiment.

FIG. 7 is a vertical cross-sectional view of a carburetor according to a conventional technique.

[Explanation of symbols]

1 ... carburetor, 2 ... mixing body, 3 ... venturi passage, 4 ... float chamber, 5 ... liquid fuel nozzle, 6 ...
Liquid fuel nozzle outlet, 7 ... Gas fuel nozzle, 8 ... Gas fuel nozzle outlet, 27 ... Choke valve, 32 ... Regulator, 33 ... Gas fuel valve, 59 ... Opening degree detection means.

─────────────────────────────────────────────────── ───Continued from the front page (56) References JP-A-7-103007 (JP, A) JP-A-3-92575 (JP, A) Fukui-Kaihei 1-63743 (JP, U) (58) Field (Int.Cl. ⁷ , DB name) F02D 19/06 F02M 21/02

Claims (2)

(57) [Claims] 1. A mixing body of a carburetor (1)
Venturi passage (3) is installed in (2), mixing body
(2) A float chamber (4) is attached, the liquid fuel nozzle (5) is communicated with the float chamber (4), and the liquid fuel nozzle outlet (6) faces the venturi passage (3). In the supply device, a gas fuel nozzle (7) is provided in the mixing body (2), and the liquid fuel nozzle outlet (6) and the gas fuel nozzle outlet are provided.
(8) and (8) face the same venturi passage (3) so that the supply of liquid fuel and gas fuel can be switched, and the supply of gas fuel to the gas fuel nozzle (7) downstream of the regulator (32) A gas fuel valve (33) for shutting off the fuel is provided, and when the fuel switching means (26) is in the liquid fuel supply state, the gas fuel valve (33) is closed, and the fuel switching means (26) is Gas fuel is being supplied,
In the case where the choke valve (27) is in the fully open side posture with a predetermined opening or more, the gas fuel valve (33) is opened and even if the fuel switching means (26) is in the gas fuel supply state. ,
A fuel supply device for an engine, wherein the gas fuel valve (33) is closed when the choke valve (27) is in a fully closed position with an opening less than a predetermined value. 2. A fuel supply system for an engine according to claim 1, wherein a gas fuel valve (33) and a choke valve (27).
A fuel supply device for an engine, characterized in that an opening detecting means (59) for detecting the opening of the engine is mounted on the mixing body (2).