WO2025011477A1 - Carburetor for general-purpose fuel engine and low-fuel evaporation system - Google Patents

Abstract

A carburetor for a general-purpose fuel engine, the carburetor comprising a float chamber (2.7), a main jet (2.8), and a balance hole (2.3), and further comprising a cut-off valve (9) and at least one first solenoid valve (2.4), wherein the cut-off valve (9) is connected to the balance hole (2.3) to prevent fuel from evaporating from the interior of the carburetor, through the balance hole, to the atmosphere so as to reduce fuel evaporation; and the first solenoid valve (2.4) is located at the bottom of the carburetor (2). When the fuel engine is in an operating state, a fuel feed hole (2.6) of the float chamber (2.7) is opened by a valve needle (2.5) of the first solenoid valve (2.4) to supply fuel to a combustion chamber of the fuel engine via the main jet (2.8); and when the fuel engine is in a stop state, the fuel feed hole (2.6) is closed by the valve needle (2.5) to block a fuel path of the main jet (2.8), which can prevent retaining and evaporation of the fuel in the fuel path behind the fuel feed hole of the carburetor so as to reduce the loss of fuel, and can also prevent the leakage of fuel and potential safety hazards by means of blocking the fuel path of the main jet. The cut-off valve (9) and the first solenoid valve (2.4) are sequentially powered off in order under the configuration of a controller to block a balance pipe opening and a fuel inlet, and then the engine is stopped, thereby solving the problem of blasting.

Description

A carburetor and low fuel evaporation system for a general fuel engine Technical Field

The invention relates to the technical field of fuel evaporation systems for fuel engines, and in particular to a carburetor and a low fuel evaporation system for general fuel engines.

Background Art

Most of the current fuel engines are internal combustion engines, which can convert the heat generated by the combustion of oil into mechanical energy. The fuel tank is a container for storing fuel in the fuel engine. The carburetor of the fuel engine is a mechanical device that mixes a certain proportion of fuel and air under the vacuum generated by the engine. It uses the kinetic energy of the inhaled air flow to achieve fuel atomization and delivers the mixed gas to the engine in a timely and appropriate amount for combustion. The carburetor plays a key role in the fuel engine, so the carburetor is also known as the heart of the engine. However, while the carburetor supplies power to the fuel engine, it also brings more serious air pollution. The fuel in the carburetor will evaporate and produce evaporative emissions. The evaporative emissions from the carburetor are relatively obvious in the evaporative emissions of the fuel engine. In the new US regulations, the requirements for fuel evaporation are that the daily evaporation of units with a displacement of 80~225cc cannot exceed 0.6g. Therefore, it is necessary to solve the problem of air pollution caused by carburetor evaporative emissions. The existing technology has made some attempts to improve and optimize the carburetor, but there is still a serious problem of evaporative emissions. Therefore, it is necessary to further research and develop new technologies to reduce the generation of carburetor evaporative emissions, thereby reducing the degree of pollution of the fuel engine to the atmospheric environment.

At the same time, the problem of backlash in existing internal combustion engine carburetors is also a problem that is difficult to deal with in the prior art. There are many reasons for backlash in fuel units. The most common one is backlash after shutdown, that is, after the user sends a shutdown signal, the combustion chamber piston continues to reciprocate due to inertia, thereby generating negative pressure at the carburetors throttle position. The method used in the prior art is to block the oil inlet at the bottom of the carburetors so that the carburetors can not spray oil, and the backlash can be prevented without fuel. For example, the invention patent "An engine carburetor and engine, working machine" with authorization announcement number CN112610365B in the prior art discloses an engine carburetor, including a carburetor body and an oil cup. The carburetor body is provided with at least one throat cavity, each throat cavity is provided with a nozzle for spraying fuel into the throat cavity and atomizing it therein, the nozzle is connected to the oil cup through an oil path, and the wall of each throat cavity is provided with a first solenoid valve for opening or closing the nozzle, the first valve needle of the first solenoid valve extends into the throat cavity and corresponds to the nozzle, the nozzle is closed by the first solenoid valve when the engine is stopped, and the nozzle is opened by the first solenoid valve when the engine is started. It can solve the problem of backfire when the engine is started or shut down, and improve the user experience.

Since the embodiment of the invention only blocks the main metering hole of the carburetor, the carburetor also has an idle metering hole, so there is still the problem of fuel being absorbed through the idle metering hole to cause backfire. At the same time, it takes time for the solenoid valve to receive the control signal and respond, and there may be a disorder in the sequence, resulting in the backfire problem.

Summary of the invention

The purpose of the present invention is to provide a carburetor and a low fuel evaporation system for a general fuel engine, which can effectively reduce the fuel evaporation loss of the fuel engine, improve fuel utilization, reduce environmental pollution, and enhance engine performance, while also avoiding the backlash phenomenon in the muffler and extending the service life of the fuel tank.

To achieve the above object, the present invention proposes the following technical solution: a carburetor for a general fuel engine, comprising a float chamber, a main nozzle and a balance hole, the carburetor also comprising a shut-off valve and at least one first solenoid valve; the shut-off valve and the first solenoid valve are connected to a controller; the controller is used to control the sequence of opening and closing of the shut-off valve and the first solenoid valve;

The shut-off valve is connected to the balancing hole and is used to cut off the balancing hole from the air when the fuel engine is in a shutdown state;

The first solenoid valve is located at the bottom of the carburetor; when the fuel engine is in a working state, the valve needle of the first solenoid valve opens the oil inlet hole of the float chamber, and supplies oil to the combustion chamber of the fuel engine through the main nozzle; when the fuel engine is in a stopped state, the valve needle blocks the oil inlet hole, blocking the oil path of the main nozzle.

Furthermore, a balancing pipe is connected between the stop valve and the balancing hole.

Furthermore, the stop valve is a second solenoid valve, a negative pressure valve or a two-way valve, among which the second solenoid valve is the best choice.

Furthermore, after receiving the fuel engine shutdown command, the controller immediately closes the stop valve and blocks the balance pipe. The air pressure on the upper layer of the oil cup is no longer higher than the air pressure at the throat of the carburetor. At this time, the valve needle is closed to block the oil inlet hole and block the oil path of the main nozzle. When the fuel engine is stopped, the valve needle blocks the oil inlet hole and blocks the oil path of the main nozzle. This can prevent the fuel from being retained and evaporated in the oil path behind the oil inlet hole of the carburetor, reducing the loss of fuel. At the same time, blocking the oil path of the main nozzle can also avoid fuel leakage and safety hazards.

The present invention also includes a low fuel evaporation system for a universal fuel engine, comprising any one of the above-mentioned carburetors.

Furthermore, the evaporation system also includes a fuel tank, a carbon canister, an adsorption pipeline, a desorption pipeline and a negative pressure pipeline;

One end of the adsorption pipeline is connected to the air outlet of the fuel tank breathing device, and the other end thereof is connected to the adsorption port of the carbon canister, and the carbon canister is provided with a first atmospheric port;

One end of the desorption pipeline is connected to the second desorption port of the carbon canister, and the other end is connected to the first desorption port of the carburetor;

The middle of the desorption pipeline passes through a negative pressure switch; one end of the negative pressure pipeline is connected to the second negative pressure port of the negative pressure switch, and the other end is connected to the first negative pressure port of the carburetor.

Furthermore, a two-way valve is installed in the middle of the adsorption pipeline.

Further, the first desorption port of the carburetor is located between the choke and the throat of the carburetor;

The first negative pressure port of the carburetor is located between the throat and the throttle of the carburetor.

Furthermore, one end of the adsorption pipeline is connected to the port of the dump valve of the fuel tank, and the other end thereof is connected to the adsorption port of the carbon canister.

Beneficial Effects

It can be seen from the above technical scheme that the technical scheme of the present invention provides a carburetor for a general fuel engine, including a float chamber, a main nozzle and a balance hole, and also includes a stop valve and at least one first solenoid valve, the stop valve is connected to the balance hole, and is used to cut off the balance hole from the air when the fuel engine is stopped, so that the fuel can be prevented from evaporating from the inside of the carburetor through the balance hole to the air, thereby reducing the evaporation of the fuel, which helps to improve the utilization rate of the fuel and reduce the fuel consumption and the generation of emissions. Compared with the prior art recorded in the background technology, the invention embodiment in the prior art is to block the main metering hole of the carburetor, but does not block the idle metering hole in the carburetor, so there is still a technical problem that the fuel is adsorbed through the idle metering hole to form a burst, which has not been solved. At the same time, it takes time for the solenoid valve to respond to the control signal, and there may be a disordered sequence, resulting in the burst problem. The present invention fully considers the uncertain factors mentioned above, and the control system sequentially closes the two solenoid valves, closes the spark plug, and shuts down to completely avoid the burst problem. The first solenoid valve is located at the bottom of the carburetor. When the fuel engine is in working state, the valve needle of the first solenoid valve opens the oil inlet hole of the float chamber and supplies oil to the combustion chamber of the fuel engine through the main nozzle. When the fuel engine is in stopping state, the valve needle blocks the oil inlet hole and blocks the oil path of the main nozzle. The opening and closing of the oil inlet hole of the float chamber can be accurately controlled by the controller controlling the first solenoid valve. When the fuel engine is in working state, the valve needle opens the oil inlet hole and allows the fuel to enter the combustion chamber through the main nozzle for oil supply, thereby realizing accurate control of the fuel supply. This helps to improve the utilization efficiency of the fuel and reduce the waste of the fuel. When the fuel engine is in stopping state, the valve needle blocks the oil inlet hole and blocks the oil path of the main nozzle. This can prevent the fuel from being retained and evaporated in the oil path behind the oil inlet hole of the carburetor and reduce the loss of the fuel. At the same time, blocking the oil path of the main nozzle can also avoid the leakage of the fuel and the safety hazard after the shutdown.

It should be appreciated that all combinations of the foregoing concepts, as well as additional concepts described in greater detail below, may be considered to be part of the inventive subject matter of the present disclosure, provided such concepts are not mutually inconsistent.

The foregoing and other aspects, embodiments and features of the present invention can be more fully understood from the following description in conjunction with the accompanying drawings. Other additional aspects of the present invention, such as the features and/or beneficial effects of the exemplary embodiments, will be apparent from the following description or learned from the practice of the specific embodiments according to the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are not drawn to scale according to actual reference objects. In the accompanying drawings, each identical or nearly identical component shown in various figures may be represented by the same reference numeral. For the sake of clarity, not every component is labeled in each figure. Now, embodiments of various aspects of the present invention will be described by way of example and with reference to the accompanying drawings, in which:

FIG1 is a structural perspective view of a low fuel evaporation system according to an embodiment of the present invention;

FIG2 is a second structural perspective view of a low fuel evaporation system according to an embodiment of the present invention;

FIG3 is an enlarged view of a portion D of FIG2 ;

FIG4 is a structural perspective view of a carburetor according to an embodiment of the present invention;

Fig. 5 is a schematic cross-sectional view along the A-A direction in Fig. 4;

FIG6 is a second structural perspective view of a carburetor according to an embodiment of the present invention;

Fig. 7 is a schematic cross-sectional view along the B-B direction in Fig. 6;

FIG8 is a third structural perspective view of a carburetor according to an embodiment of the present invention;

Fig. 9 is a schematic cross-sectional view along the C-C direction in Fig. 8;

FIG10 is a structural perspective view of a carburetor according to an embodiment of the present invention;

Fig. 11 is a cross-sectional schematic diagram along the D-D direction in Fig. 10;

FIG12 is a schematic diagram of the connection between the gas outlet of the oil tank and the adsorption pipeline;

FIG. 13 is a schematic diagram showing the connection between the dump valve of the oil tank and the adsorption pipeline.

In the figure, the meanings of the reference numerals are as follows:

1-Fuel tank; 1.1-Air outlet; 1.2-Fuel tank cap; 1.3-Dump valve; 2-Carburetor; 2.1-First negative pressure port; 2.2-First desorption port; 2.3-Balance hole; 2.4-First solenoid valve; 2.5-Valve needle; 2.6-Oil inlet hole; 2.7-Float chamber; 2.8-Main nozzle; 3-Carbon canister; 3.1-First atmospheric port; 3.2-Second desorption port; 3.3-Adsorption port; 4-Two-way valve; 5-Adsorption pipeline; 6-Desorption pipeline; 7-Negative pressure switch; 7.1-First connecting port; 7.2-Second connecting port; 7.3-Second negative pressure port; 8-Negative pressure pipeline; 9-Stop valve; 10-Balance pipe.

DETAILED DESCRIPTION

In order to make the purpose, technical solution and advantages of the embodiment of the present invention clearer, the technical solution of the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings of the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, not all of the embodiments. Based on the described embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Unless otherwise defined, the technical terms or scientific terms used herein should be the common meaning understood by people with general skills in the field to which the present invention belongs.

The words "first", "second" and similar words used in the patent application specification and claims of the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, unless the context clearly indicates otherwise, the singular form of "a", "an" or "the" and other similar words do not indicate a quantitative limitation, but indicate the existence of at least one. "Include" or "comprise" and other similar words mean that the elements or objects appearing before "include" or "comprise" cover the features, wholes, steps, operations, elements and/or components listed after "include" or "comprise", and do not exclude the existence or addition of one or more other features, wholes, steps, operations, elements, components and/or their collections. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, which only illustrate the basic structure of the present invention in a schematic manner, and therefore only show the components related to the present invention.

In recent years, the research and development and application of low evaporation in fuel engines have received increasing attention. Low fuel evaporation aims to reduce the evaporation loss of automobile fuel when not in operation, improve fuel economy and environmental friendliness. By optimizing the carburetor device, the evaporation loss of fuel can be effectively reduced and the fuel utilization rate can be improved, which not only helps to save energy and reduce fuel costs, but also reduces the negative impact on the environment.

Referring to Figures 2 and 3, a carburetor for a general fuel engine provided by an embodiment of the present invention includes a float chamber 2.7, a main nozzle 2.8 and a balancing hole 2.3. The carburetor 2 also includes a shut-off valve 9 and at least one first solenoid valve 2.4. The shut-off valve 9 is connected to the balancing hole 2.3 and is used to cut off the balancing hole 2.3 from the air when the fuel engine is stopped. This can prevent the fuel from evaporating from the inside of the carburetor 2 through the balancing hole 2.3 to the air, thereby reducing the evaporation of the fuel, which helps to improve the utilization rate of the fuel and reduce the fuel consumption and the generation of emissions.

The first solenoid valve 2.4 is located at the bottom of the carburetor 2. Under normal conditions, when the fuel engine is in operation, the valve needle 2.5 of the first solenoid valve 2.4 opens the oil inlet hole 2.6 of the float chamber 2.7, and supplies oil to the combustion chamber of the fuel engine through the main nozzle 2.8. When the fuel engine is stopped, the valve needle 2.5 blocks the oil inlet hole 2.6, blocking the oil path of the main nozzle 2.8. The opening and closing of the oil inlet hole 2.6 of the float chamber 2.7 can be accurately controlled by the control of the first solenoid valve 2.4. When the fuel engine is in operation, the valve needle 2.5 blocks the oil inlet hole 2.6, blocking the oil path of the main nozzle 2.8. .5 opens the oil inlet hole 2.6, allowing the fuel to enter the combustion chamber through the main nozzle 2.8 for fuel supply, thereby achieving precise control of the fuel supply, which helps to improve the utilization efficiency of the fuel and reduce the waste of fuel; when the fuel engine is stopped, the valve needle 2.5 blocks the oil inlet hole 2.6 and blocks the oil path of the main nozzle 2.8, which can prevent the fuel from being retained and evaporated in the oil path behind the oil inlet hole 2.6 of the carburetor 2, reducing the loss of fuel. At the same time, blocking the oil path of the main nozzle 2.8 can also avoid fuel leakage and safety hazards.

1-Fuel tank; 1.1-Air outlet; 1.2-Fuel tank cap; 1.3-Dump valve; 2-Carburetor; 2.1-First negative pressure port; 2.2-First desorption port; 2.3-Balance hole; 2.4-First solenoid valve; 2.5-Valve needle; 2.6-Oil inlet hole; 2.7-Float chamber; 2.8-Main nozzle; 3-Carbon canister; 3.1-First atmospheric port; 3.2-Second desorption port; 3.3-Adsorption port; 4-Two-way valve; 5-Adsorption pipeline; 6-Desorption pipeline; 7-Negative pressure switch; 7.1-First connecting port; 7.2-Second connecting port; 7.3-Second negative pressure port; 8-Negative pressure pipeline; 9-Stop valve; 10-Balance pipe.

In order to achieve the technical effect of preventing backfire, after the user gives the shutdown signal, the controller first cuts off the power and blocks the balance pipe mouth of the carburetor 2, and then shuts down and blocks the first electromagnetic valve 2.4 at the bottom. The reason for this sequence is that after the user gives the shutdown signal, the combustion chamber piston cannot stop immediately due to inertia and will continue to reciprocate. If the frequency of the fuel engine is 60Hz, there is still negative pressure at the throat of the carburetor 2. In the normal working state, the fuel is sprayed 30 times per second, and a faster frequency of fuel flow will be formed at the oil inlet of the first electromagnetic valve 2.4 of the carburetor 2. If the balance pipe mouth is blocked first, the air pressure of the upper layer of the oil cup is no longer higher than the air pressure at the throat of the carburetor, then the fuel will first enter a static state and no longer spray. At this moment, the first electromagnetic valve 2.4 at the bottom is turned off, which is more friendly to the first electromagnetic valve 2.4 at the bottom, and can prevent damage caused by unstable oil pressure, thereby increasing the life of the bottom electromagnetic valve. After the two valves are shut down in turn to block the balance pipe mouth and the oil inlet 2, this state can perfectly solve the problem of backfire.

However, the expected time for the fuel to enter a static state is usually 4-5 seconds, and a burst may still occur during this time period. Therefore, within the expected time period, the controller needs to calculate the vibration waveform of the fuel after the valve needle 2.5 blocks the oil inlet hole 2.6 and the waveform of the mechanical vibration of the carburetor itself. At this time, the stop valve 9 needs to use a second solenoid valve. Please refer to Figure 1. The stop valve 9 of the carburetor provided in the embodiment of the present invention is a second solenoid valve. As an electric actuator, the solenoid valve has a fast response speed. When the control signal changes, the second solenoid valve can be opened or closed quickly to achieve rapid control of the flow of the medium. The solenoid valve only needs current supply when working, and does not consume energy in the closed state. Compared with other types of actuators, the solenoid valve has lower energy consumption, can save energy costs, and the solenoid valve has a simple structure, and is relatively easy to maintain and replace. Under the action of the controller, the second solenoid valve is closed when the two waveform peaks overlap, and then opened, and closed again when the two waveform peaks overlap next time, and the closing action is repeated until the fuel is in a stable state. Considering the durability of the equipment, the second solenoid valve cannot be opened and closed too frequently. Therefore, the efficient force of the second solenoid valve will be the key technical point to make the fuel quickly enter a static state. In actual use, the closing action is repeated 3-4 times.

It should be noted here that: for the 60Hz generator involved in the present invention: there are 120 strokes in one second, and work is done once every four strokes. In fact, the ordinary second solenoid valve can be opened and closed 30 times per second, that is, in each of the four strokes, the second solenoid valve is opened in the intake stroke state, and the second solenoid valve is closed in the other three strokes, so that the best effect of rapid and stable fuel can be achieved. However, this will cause the second solenoid valve to be opened and closed too frequently, greatly reducing its service life. In the present invention, the opening frequency of the second solenoid valve is comprehensively considered in combination with the state of the ignition advance angle. By calculating the point where the vibration waveform generated by the fuel and the waveform peak of the mechanical vibration of the carburetor itself are superimposed, the second solenoid valve is closed when the peaks of the two are superimposed, thereby achieving the most efficient technical effect of stabilizing fuel fluctuations. In this way, the actual time for the fuel to enter the static state is compressed to within 1.5 seconds, and in most cases it is completed within 1.2 seconds. Thereby ensuring that no bursting phenomenon occurs during this time period. In fact, in this process, the service life of the second solenoid valve is sacrificed, while the service life of the first solenoid valve 2.4 itself is extended.

Please refer to Figures 1, 6 and 7. A balancing pipe 10 is connected between the stop valve 9 and the balancing hole 2.3 of the carburetor provided in the embodiment of the present invention. The stop valve 9 is connected to the carburetor 2 through the balancing pipe 10, which can effectively control the evaporation of fuel. When the engine stops running, the stop valve 9 is closed to prevent the fuel from evaporating and dissipating in the carburetor, thereby reducing fuel loss. The setting of the balancing pipe 10 can facilitate the inspection and maintenance of the stop valve 9.

Please refer to Figure 1. The stop valve 9 of the carburetor provided in the embodiment of the present invention is a negative pressure valve. When the fuel engine is stopped, the negative pressure valve blocks the balance hole 2.3, so that the balance hole 2.3 is cut off from the air, preventing the fuel from evaporating from the inside of the carburetor 2 to the air through the balance hole 2.3, thereby reducing the evaporation of the fuel. Due to the working principle of the negative pressure valve itself, it requires the negative pressure transmitted from the first negative pressure port 2.1 of the carburetor 2 to be realized. In this way, the connection and disconnection of the balance hole 2.3 and the atmosphere can be controlled synchronously and more accurately, which plays a more active role in reducing the evaporation of the fuel; when the fuel engine is working, the negative pressure valve will open, and the carburetor 2 will balance the pressure inside the system through the balance hole 2.3.

Please refer to Figure 1. The stop valve 9 of the carburetor provided in the embodiment of the present invention is a two-way valve. When the fuel engine is stopped, the two-way valve channel closes the connection between the balancing hole 2.3 and the air, so that the balancing hole 2.3 is cut off from the air, preventing the fuel from evaporating from the inside of the carburetor 2 through the balancing hole 2.3 to the air, thereby reducing the evaporation of the fuel; when the fuel engine is working, the two-way valve channel opens the connection between the balancing hole 2.3 and the air, and the carburetor 2 balances the pressure inside the system through the balancing hole 2.3.

Please refer to Figures 1 to 11. An embodiment of the present invention provides a low fuel evaporation system for a general fuel engine, including any one of the above-mentioned carburetors 2. In the low fuel evaporation system, the functions that can be achieved by the above-mentioned carburetors 2 can also be achieved in the low fuel evaporation system.

Please refer to Figures 1 to 8. The low fuel evaporation system provided by the embodiment of the present invention also includes a fuel tank 1, a carbon canister 3, an adsorption pipeline 5, a desorption pipeline 6 and a negative pressure pipeline 8; one end of the adsorption pipeline 5 is connected to the air outlet 1.1 of the breathing device of the fuel tank 1, and the other end thereof is connected to the adsorption port 3.3 of the carbon canister 3, and the carbon canister 3 is provided with a first atmospheric port 3.1; one end of the desorption pipeline 6 is connected to the second desorption port 3.2 of the carbon canister 3, and the other end is connected to the first desorption port 2.2 of the carburetor 2; the middle of the desorption pipeline 6 passes through the negative pressure switch 7; one end of the negative pressure pipeline 8 is connected to the second negative pressure port 7.3 of the negative pressure switch 7, and the other end is connected to the first negative pressure port 2.1 of the carburetor 2.

For the adsorption pipeline 5, the air inlet of the breathing device of the fuel tank 1 is located above the liquid level of the fuel tank 1, and its air outlet 1.1 is connected to the adsorption pipeline 5, so that the oil vapor evaporated from the fuel tank 1 is stored in the carbon canister 3 through the adsorption pipeline 5. When the fuel tank 1 is under negative pressure, air can also be replenished into the fuel tank 1 through the first air port 3.1 of the carbon canister 3 to ensure that the interior of the fuel tank 1 is in a necessary air pressure state. By storing the oil vapor evaporated from the fuel tank 1 in the carbon canister 3, the volatilization and leakage of the oil vapor can be effectively prevented. The interior of the carbon canister 3 is usually filled with adsorption materials such as activated carbon, which can adsorb and filter impurities in the oil vapor, improve the purity of the oil vapor, and reduce damage to the engine. The setting of the adsorption pipeline 5 helps to reduce the evaporation of oil vapor into the atmosphere and improve the safety of the fuel system.

As for the desorption pipeline 6, the carbon canister 3 and the carburetor 2 are connected together through the desorption pipeline 6. The desorption pipeline 6 can be used to discharge and process the fuel in the carbon canister 3. The middle of the desorption pipeline 6 also passes through a negative pressure switch 7, that is, the carburetor 2 is connected to the first connection port 7.1 of the negative pressure switch 7 through a section of the desorption pipeline 6, and the carbon canister 3 is connected to the second connection port 7.2 of the negative pressure switch 7 through another section of the desorption pipeline 6. The negative pressure switch 7 can effectively control the reuse of the fuel stored in the carbon canister 3; the negative pressure switch 7 has three functions. First, when the fuel engine is working, the negative pressure switch 7 is opened to desorb the fuel in the carbon canister, thereby reducing the fuel adsorbed by the activated carbon in the carbon canister; second, when the fuel engine stops working, the negative pressure switch 7 is closed to disconnect the desorption pipeline 6 to prevent the evaporated fuel in the carbon canister 3 from leaking into the carburetor 2; third, the negative pressure switch 7 synchronizes the desorption state with the fuel supply state of the carburetor 2. When the fuel engine is in a high load state, the negative pressure switch 7 can also increase the desorption frequency from the carbon canister 3.

For the negative pressure pipeline 8 , by connecting the negative pressure switch 7 and the carburetor 2 , the negative pressure pipeline 8 can realize negative pressure control of the negative pressure switch 7 .

Please refer to FIG1 . The low fuel evaporation system provided by the embodiment of the present invention has a two-way valve 4 installed in the middle of the adsorption pipeline 5. The installation of the two-way valve 4 in the middle of the adsorption pipeline 5 can control the flow direction of the evaporation gas. When the oil vapor inside the fuel tank 1 is too much and the air pressure is too high, the pressure difference on both sides of the two-way valve 4 exceeds the critical value, and the two-way valve 4 is forwardly conducted. At this time, the carbon canister 3 adsorbs the excess oil vapor inside the fuel tank 1, so that the pressure inside the fuel tank 1 is maintained within the required range. When the air pressure inside the fuel tank 1 is too low, the two-way valve 4 is negatively conducted in the same way, and air is added to the fuel tank 1 through the first air port 3.1 of the carbon canister 3. The necessary pressure inside the fuel tank 1 can also be adjusted by adjusting the opening and closing pressure of the two-way valve 4.

Please refer to Figures 3 to 7. In the low fuel evaporation system provided by the embodiment of the present invention, the first desorption port 2.2 of the carburetor 2 is located between the choke and the throat of the carburetor 2; the choke is an important component for regulating the air flow entering the carburetor 2. Locating the first desorption port 2.2 between the choke and the throat can ensure the normal operation of the choke and is also beneficial to the stable operation of the engine.

The first negative pressure port 2.1 of the carburetor 2 is located between the throat and the throttle of the carburetor 2; placing the first negative pressure port 2.1 between the throat and the throttle of the carburetor 2 can provide a negative pressure state for the fuel system through the negative pressure switch 7, while minimizing the impact on the operation of the carburetor 2.

Please refer to Figure 9. In the low fuel evaporation system provided by an embodiment of the present invention, one end of the adsorption pipeline 5 is connected to the port of the dump valve 1.3 of the fuel tank 1, and the other end thereof is connected to the adsorption port 3.3 of the carbon canister 3; in the existing fuel tanks, the breathing device of some fuel tanks 1 is the dump valve 1.3. For this type of fuel tank 1, the adsorption pipeline 5 can be directly connected to the port of the dump valve 1.3 of the fuel tank 1 to establish a ventilation channel between the adsorption pipeline 5 and the fuel tank 1.

Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. A person with ordinary knowledge in the technical field to which the present invention belongs may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be determined by the definition of the claims.

Claims (9)

A carburetor for a universal fuel engine, comprising a float chamber (2.7), a main nozzle (2.8) and a balance hole (2.3), characterized in that the carburetor (2) further comprises a stop valve (9) and at least one first solenoid valve (2.4), and the stop valve (9) and the first solenoid valve (2.4) are connected to a controller; The stop valve (9) is connected to the balancing hole (2.3) and is used to cut off the balancing hole (2.3) from air when the fuel engine is in a stopped state; The first solenoid valve (2.4) is located at the bottom of the carburetor (2); The controller is used to control the opening and closing sequence and interval time of the stop valve (9) and the first solenoid valve (2.4). The carburetor according to claim 1, characterized in that a balancing pipe (10) is connected between the stop valve (9) and the balancing hole (2.3). The carburetor according to claim 1, characterized in that the shut-off valve (9) is a second solenoid valve, a negative pressure valve or a two-way valve. The carburetor according to claim 1 is characterized in that, after receiving the fuel engine shutdown command, the controller immediately closes the stop valve (9) to block the balance pipe opening, and the air pressure on the upper layer of the oil cup is no longer higher than the air pressure at the throat of the carburetor. At this time, the valve needle (2.5) is closed to block the oil inlet hole (2.6) and block the oil path of the main nozzle (2.8); when the fuel engine is in the shutdown state, the valve needle (2.5) blocks the oil inlet hole (2.6) and blocks the oil path of the main nozzle (2.8). A low fuel evaporation system for a general fuel engine, characterized by comprising a carburetor (2) as claimed in any one of claims 1 to 4. The evaporation system according to claim 5, characterized in that the evaporation system further comprises an oil tank (1), a carbon canister (3), an adsorption pipeline (5), a desorption pipeline (6) and a negative pressure pipeline (8); One end of the adsorption pipeline (5) is connected to the air outlet (1.1) of the breathing device of the oil tank (1), and the other end is connected to the adsorption port (3.3) of the carbon canister (3), and the carbon canister (3) is provided with a first air port (3.1); One end of the desorption pipeline (6) is connected to the second desorption port (3.2) of the carbon canister (3), and the other end is connected to the first desorption port (2.2) of the carburetor (2); The middle of the desorption pipeline (6) passes through a negative pressure switch (7); one end of the negative pressure pipeline (8) is connected to the second negative pressure port (7.3) of the negative pressure switch (7), and the other end is connected to the first negative pressure port (2.1) of the carburetor (2). The evaporation system according to claim 6, characterized in that a two-way valve (4) is installed in the middle of the adsorption pipeline (5). The evaporation system according to claim 6, characterized in that The first desorption port (2.2) of the carburetor (2) is located between the choke and the throat of the carburetor (2); The first negative pressure port (2.1) of the carburetor (2) is located between the throat and the throttle of the carburetor (2). The evaporation system according to claim 6, characterized in that one end of the adsorption pipeline (5) is connected to the port of the dump valve (1.3) of the fuel tank (1), and the other end thereof is connected to the adsorption port (3.3) of the carbon canister (3).