CN115163314A - Single-cylinder carburetor type engine flameout and fuel cut-off control device and control method thereof - Google Patents

Abstract

The invention relates to a single-cylinder carburetor type engine flameout and fuel-cut control device and a control method thereof, and the single-cylinder carburetor type engine flameout and fuel-cut control device comprises an air supplementing assembly, a flameout switch (1), an idle speed contact switch (2), an engine rotating speed sensor (6), a driving wheel speed sensor (7), a gear switch (8) and a control unit (3), wherein the air supplementing assembly comprises an air supplementing electromagnetic valve (5), and the control unit (3) is respectively connected with the air supplementing electromagnetic valve (5), the flameout switch (1), the idle speed contact switch (2), the engine rotating speed sensor (6), the driving wheel speed sensor (7) and the gear switch (8) through a first signal wire, a second signal wire, a third signal wire, a fourth signal wire, a fifth signal wire and a sixth signal wire. Compared with the prior art, the invention has the beneficial effects that: the installation is convenient, energy-conserving safety, effectively prevents that the high vacuum degree effect of throat department from spouting into the throat under the indoor fuel of carburetor float after the engine idling or flame-out, saves fuel consumption by a wide margin.

Description

Single-cylinder carburetor type engine flameout control device and control method thereof

This application is a divisional application for the invention patent titled "Single-cylinder carburetor-type engine flameout and fuel cut-off control device and control method thereof"; the application number of the parent application is: CN201710391979.3; the application of the parent application Date: 2017-05-27.

technical field

The invention relates to the technical field of an engine flameout and fuel cutoff control device and a control method thereof, in particular to a single-cylinder carburetor type engine flameout and fuel cutoff control device and a control method thereof.

Background technique

Usually, when the throttle valve of the carburetor is suddenly closed (stopping or forced idling), the air pressure at the throat of the carburetor and the idling nozzle is reduced due to the instantaneous increase in the vacuum of the intake manifold, resulting in The fuel in the carburetor float chamber is ejected from the idle nozzle and the main nozzle and enters the cylinder under the action of vacuum. Obviously, this part of the extremely rich fuel cannot be completely burned, resulting in fuel waste. Therefore it is in urgent need of improvement.

The Chinese invention patent with the patent number ZL200710075108.7 discloses a new complete set of electronically controlled air supply system device for motor vehicles, especially motorcycles with European No. 3 emission standards or above, mainly composed of electronic controller (ECU) , The primary air supply solenoid valve (high-frequency airflow control valve) and the secondary air supply solenoid valve (airflow control valve), catalytic converters, air filters, related sensing components, connecting pipes and connecting wiring harnesses and other components. According to the operation changes of the engine, the electronic controller (ECU) sends the control commands of opening and closing to the primary and secondary air supply solenoid valves of the system device respectively, that is, the primary and secondary air supply, to effectively improve the Engine air-fuel ratio and reduce harmful gas emissions. In addition, the internal structure and connection mode of the solenoid valve are continuously improved and optimized, which further improves the reliability of the system device, reduces the cost, and is suitable for mass production. However, the electronic controller described in this invention is not provided with control devices for the flameout switch, idle speed contact switch, engine speed, driving wheel speed and gear switch, so it is impossible to realize the timely closure of the engine throttle valve of the carburetor-type engine when the engine throttle valve is suddenly closed. Controlling the engine to turn off the engine and cut off the oil, so there are still the following technical defects: at this time, due to the instantaneous increase in the vacuum degree of the intake manifold, the airflow pressure at the carburetor throat and the idle nozzle is reduced, resulting in the carburetor float chamber. The fuel is ejected from the idle nozzle and the main nozzle and enters the cylinder under the action of vacuum, and this part of the extremely rich fuel cannot be completely burned, resulting in fuel waste.

Therefore, there is an urgent need in the market for a single-cylinder carburetor-type engine flameout control device and a control method thereof to solve the above problems.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a single-cylinder carburetor type engine flameout and fuel cut-off control device and a control method thereof, which are used to solve the technical problems existing in the above-mentioned prior art. Component runs.

For achieving the above object, the present invention provides the following scheme:

A single-cylinder carburetor type engine flameout and fuel cutout control device, comprising an air supply assembly, a flameout switch, an idle speed contact switch, an engine speed sensor, a drive wheel wheel speed sensor, a gear switch and a control unit, the air supply assembly includes a supplementary air solenoid valve, the control unit communicates with the air supply solenoid valve, the flameout switch, the The idle speed contact switch, the engine speed sensor, the driving wheel speed sensor and the gear switch are connected.

Preferably, the air supply assembly includes an air filter, an intake three-way pipe, an engine, a carburetor and an air supply hose.

In any of the above solutions, it is preferable that the left and right ports of the intake three-way pipe are respectively connected with the port of the mixture pipe between the carburetor and the engine.

In any of the above solutions, preferably, the upper port of the air intake three-way pipe is connected to the air filter through the air supply hose.

In any of the above solutions, preferably, the air supplement solenoid valve is installed on the air supply hose near the upper port of the intake tee.

In any of the above solutions, preferably, the control unit includes a single-chip microcomputer and a power amplifier, and the power amplifier is connected to the air supplement solenoid valve.

In any of the above solutions, preferably, an accelerator handle is included, and the flameout switch is installed at the accelerator handle.

Preferably in any of the above solutions, an accelerator cable is included, and the idle speed contact switch is installed on the accelerator cable.

Preferably in any of the above solutions, an engine wiring harness is included, and the control unit is mounted on the engine wiring harness.

In any of the above solutions, preferably, the engine includes a cylinder block, and the engine speed sensor is mounted on the cylinder block.

In any of the above solutions, preferably, the engine includes an igniter, and the engine speed sensor is installed at the igniter.

In any of the above solutions, preferably, the engine includes a magneto, and the engine speed sensor is installed at the magneto.

In any of the above solutions, preferably, an odometer is included, and the driving wheel wheel speed sensor is installed at the odometer.

In any of the above solutions, preferably, the engine includes a transmission, and the gear switch is installed in the transmission.

In any of the above solutions, preferably, the engine speed sensor adopts a Hall sensor.

In any of the above solutions, preferably, the engine rotational speed sensor adopts a photoelectric rotational speed sensor.

In any of the above solutions, preferably, the engine speed sensor adopts a capacitive speed sensor.

In any of the above solutions, preferably, the engine rotational speed sensor adopts a variable reluctance type rotational speed sensor.

In any of the above solutions, preferably, the photoelectric rotational speed sensor adopts a direct-illuminated photoelectric rotational speed sensor.

In any of the above solutions, preferably, the photoelectric rotational speed sensor adopts a reflective photoelectric rotational speed sensor.

In any of the above solutions, preferably, the photoelectric rotational speed sensor adopts a projection photoelectric rotational speed sensor.

In any of the above solutions, preferably, the capacitive rotational speed sensor is an area-variable capacitive rotational speed sensor.

In any of the above solutions, it is preferable that the capacitive rotational speed sensor adopts a medium-change capacitive rotational speed sensor.

In any of the above solutions, preferably, the variable reluctance type rotational speed sensor adopts an inductive rotational speed sensor.

In any of the above solutions, preferably, the variable reluctance type rotational speed sensor adopts a transformer type rotational speed sensor.

In any of the above solutions, preferably, the variable reluctance type rotational speed sensor adopts an eddy current rotational speed sensor.

In order to solve the technical defects existing in the above-mentioned existing control methods for the electronically controlled air supply system of the engine, the technical solution adopted in the present invention is as follows: a single-cylinder carburetor type engine flameout and oil-cut control method, and the device for implementing the method includes any of the above preferred solutions. A single-cylinder carburetor type engine flameout and fuel cutout control device, preferably, including a control working mode that prevents fuel from being ejected from the carburetor during flameout: through the flameout switch and the idle speed contact The switch reads the flameout switch signal and the idle contact switch signal and sends them to the control unit. The control unit determines whether the throttle valve is in a state of rapid closing or whether the flameout switch is in an on state. The control unit judges that the engine is in a flameout state and issues a control command, the control command is sent to the air supplement solenoid valve through the power amplifier, and the air supplement solenoid valve opens immediately and supplies air to the intake three-way pipe. , to reduce the vacuum degree after the throttle valve to prevent the fuel from spraying out of the idle oil passage.

In any of the above solutions, it is preferable to include a control working mode that prevents the carburetor from injecting fuel when the vehicle is coasting: the control unit continuously scans the signal of the engine speed sensor, the driving wheel speed sensor signal and the gear switch signal, once the engine speed is lower than the reduced wheel speed, no matter what position the throttle valve is in and whether the flameout switch is in the on state, the control unit will issue a control command, so The control command is sent to the air supply solenoid valve through the power amplifier, and the air supply solenoid valve is opened immediately to supply air to the intake three-way pipe, and at the same time, the ignition switch on the igniter is closed to complete the process. The engine is turned off to prevent the fuel from being ejected from the main oil passage or the idle oil passage of the carburetor; when the rotational speed signal sent by the engine rotational speed sensor to the control unit is zero, the engine stops rotating , the control unit then sends a control command to the air supplement solenoid valve to control the gas supplement solenoid valve to complete the power-off reset action.

The reduced wheel speed refers to the wheel speed multiplied by the gear ratio between the engine and the drive wheels.

In any of the above solutions, it is preferable to include a normal working mode of the engine: when the control working mode of preventing fuel from being sprayed from the carburetor when the engine is turned off is not satisfied and the vehicle is coasting to prevent the carburetor from being satisfied. Under the premise of the control working mode of fuel injection, the control unit does not send any control command to the air supplement solenoid valve, and the engine is in a normal working state at this time.

The present invention has achieved the following technical effects with respect to the prior art:

The invention is suitable for the carburetor type engine of energy-saving racing cars or motorcycles, and is easy to install, energy-saving and safe, and can effectively prevent the fuel in the carburetor float chamber from being sprayed into the throat under the action of high vacuum at the throat after the engine is idling or stopped. port, thereby saving fuel consumption significantly. At the same time, the present invention does not affect the normal braking of the energy-saving competitive vehicle or the motorcycle during use.

Description of drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings required in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some of the present invention. In the embodiments, for those of ordinary skill in the art, other drawings can also be obtained according to these drawings without any creative effort.

1 is a schematic structural diagram of a preferred embodiment of the single-cylinder carburetor-type engine flameout and oil-cut control device of the present invention;

FIG. 2 is a schematic diagram of the frame structure of a preferred embodiment of the single-cylinder carburetor type engine flameout and fuel-cut control device of the present invention.

Description of reference numerals: 1 flameout switch; 2 idle speed contact switch; 3 control unit; 4 power amplifier; 5 air intake solenoid valve; 6 engine speed sensor; 7 drive wheel speed sensor; 8 gear switch; 9 intake three 10 Carburetor; 11 Air Filter; 12 Air Supply Hose; 13 Spark Plug; 14 Engine; 15 Throttle Cable; 16 Igniter.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

The purpose of the present invention is to provide a single-cylinder carburetor type engine flameout and fuel cut-off control device and a control method thereof, which are used to solve the technical problems existing in the above-mentioned prior art. Component runs.

In order to make the above objects, features and advantages of the present invention more clearly understood, the present invention will be described in further detail below with reference to the accompanying drawings and specific embodiments.

Embodiment 1.

As shown in Figures 1-2, the present embodiment provides a single-cylinder carburetor-type engine flameout and fuel cutout control device, including an air supply component, a flameout switch 1, an idle speed contact switch 2, an engine speed sensor 6, a drive Wheel speed sensor 7, gear switch 8 and control unit, the air supply component includes air supply solenoid valve 5, and the control unit 3 passes through the first signal line, the second signal line, the third signal line and the fourth signal line respectively. , The fifth signal line and the sixth signal line are connected with the air supplement solenoid valve 5 , the flameout switch 1 , the idle speed contact switch 2 , the engine speed sensor 6 , the driving wheel wheel speed sensor 7 and the gear switch 8 .

The air supply assembly includes an air filter 11, an intake three-way pipe 9, an engine 14, a carburetor 10 and an air supply hose 12. The left and right ports of the intake three-way pipe 9 are respectively connected to the carburetor 10 and the carburetor 10 and the air supply hose 12. The ports of the mixture pipes between the engines 14 are connected, the upper port of the intake three-way pipe 9 is connected to the air filter 11 through the air supply hose 12, and the air supplement solenoid valve 5 is installed near the intake three-way pipe 9. On the air supply hose 12 at the upper port.

The control unit 3 includes a single-chip microcomputer and a power amplifier 4 , and the power amplifier 4 is connected with the air supplement solenoid valve 5 . Including the accelerator handle, the flameout switch 1 is installed at the accelerator handle. Including the throttle cable 15, the idle contact switch 2 is installed on the throttle cable 15. Including the engine wiring harness on which the control unit 3 is mounted. The engine 14 includes a cylinder block on which the engine speed sensor 6 is mounted. The engine 14 includes an igniter 16 at which the engine speed sensor 6 is mounted. The engine 14 includes a magneto at which the engine speed sensor 6 is mounted. An odometer is included, at which a drive wheel wheel speed sensor 7 is mounted. Engine 14 includes a transmission within which range switch 8 is mounted.

The engine rotational speed sensor 6 may adopt a Hall sensor, a photoelectric rotational speed sensor, a capacitive rotational speed sensor, or a variable reluctance rotational speed sensor. The photoelectric rotational speed sensor may be a direct-illuminated photoelectric rotational speed sensor, a reflective photoelectric rotational speed sensor, or a projected photoelectric rotational speed sensor. The capacitive rotational speed sensor may be an area-variable capacitive rotational speed sensor or a medium-variable capacitive rotational speed sensor. The variable reluctance type rotational speed sensor may use an inductive rotational speed sensor sensor, a transformer rotational speed sensor sensor, or an eddy current rotational speed sensor sensor.

The rotational speed sensor is a sensor that converts the rotational speed of a rotating object into an electrical output. It is an indirect measuring device and can be manufactured by mechanical, electrical, magnetic, optical and hybrid methods. According to the different signal forms, rotational speed sensors can be divided into Both analog and digital. The rotational speed sensor uses a magneto-resistor as the sensing element, and the core component uses the magneto-resistor as the detection element, and then through a brand-new signal processing circuit, the noise is reduced and the function is more complete. Compared with the output waveforms of other gear type speed sensors, the measured speed error is extremely small, and the linear characteristics have good consistency. The sensing objects are magnetic materials or magnetic conductive materials, such as magnetic steel, iron and electrical steel. When there is a convex (or concave) magnetic or magnetically conductive material on the measured object, when the measured object rotates, the sensor outputs a pulse signal related to the rotation frequency to achieve the purpose of speed measurement or displacement detection.

The photoelectric speed sensor is an angular displacement sensor, which is composed of a disc with a slot, a light source, a photoelectric device and an indicating slot disc mounted on the measured shaft. It has non-contact, high precision, high resolution and high reliability. And the technical advantages of fast response, etc., have been widely used in the field of detection and control. The direct-illuminated photoelectric speed sensor is composed of a perforated disc, a light source, a photosensitive element and a slit plate. On the photosensitive element and received by the photosensitive element, the optical signal is converted into an electrical signal for output. There are many small holes on the perforated disk. When the perforated disk rotates once, the number of electrical pulses output by the photosensitive element is equal to the opening of the disk. The number of holes, therefore, the measured rotational speed can be known by measuring the pulse frequency output by the photosensitive element. The reflective photoelectric speed sensor is mainly composed of the rotating part to be tested, the reflective sheet (or reflective sticker), and the reflective photoelectric sensor. When accurate positioning is possible, a plurality of reflective sheets or reflective sheets are symmetrically installed on the tested part. Stickers will achieve better measurement results; when the test distance is short and the test requirements are not high, only a reflective sticker can be installed on the tested part. At this time, when the reflective sticker on the rotating part passes in front of the photoelectric sensor, the photoelectric The output of the sensor will jump once, and by measuring the jump frequency f, the speed n can be known. The reading plate and the measuring plate of the projection type photoelectric speed sensor have gaps with the same interval. The measuring plate rotates with the object to be measured. Every time a gap is rotated, the light projected from the light source to the photosensitive element produces a light and dark change, and the photosensitive element is Output current pulse signal. The reflective photoelectric speed sensor is provided with a reflection mark on the shaft to be measured. The light emitted by the light source is incident on the shaft to be measured through the lens and semi-permeable film. When the shaft rotates, the reflection mark reflects the projected light spot. When the reflectivity changes and the reflectivity increases, the reflected light is projected onto the photosensitive element through the lens, and a pulse signal is sent; when the reflectivity becomes small, the photosensitive element has no signal. .

The area-varying capacitive speed sensor is composed of two fixed metal plates and a movable metal plate connected to the rotating shaft. The movable metal plate is at the position with the largest capacitance, and when the rotating shaft rotates 180°, it is at the smallest capacitance The position of , the periodic change rate of the capacitance is the rotational speed, and the measurement signal of the rotational speed can be obtained by means of DC excitation, AC excitation, and an oscillatory tank circuit formed by a variable capacitor. The dielectric change capacitive speed sensor is formed by embedding a high dielectric constant movable plate between the two fixed electrode plates of the capacitor. The movable dielectric plate is connected with the rotating shaft, and with the rotation of the rotating shaft, The periodic change of the dielectric constant between the capacitor plates causes the periodic change of the capacitance at a rate equal to the rotational speed of the rotating shaft.

Embodiment two,

This embodiment provides a single-cylinder carburetor-type engine flameout and fuel-cut control method, and a device for implementing the method includes any one of the technical solutions for the single-cylinder carburetor-type engine flameout and fuel-cut control device in the first embodiment, including The following working modes:

Control working mode to prevent fuel from being ejected from the carburetor 10 when the flame is turned off: The flame-off switch signal and the idle contact switch signal are read through the flame-off switch 1 and the idle contact switch 2 respectively and sent to the control unit 3. The control unit 3 judges the node Whether the valve is in a rapid closing state or whether the flameout switch 1 is in an ON state, if it is judged to be yes, the control unit 3 determines that the engine is in a flameout state and issues a control command, which is sent to the air supplement solenoid valve 5 through the power amplifier 4, The air supply solenoid valve 5 opens immediately and supplies air to the intake three-way pipe 9, so as to reduce the vacuum degree after the throttle valve, so as to prevent the fuel from being ejected from the idling oil passage.

The control working mode in which the vehicle prevents the carburetor 10 from injecting fuel when the vehicle is coasting: the control unit 3 continuously scans the signal of the engine speed sensor 6, the driving wheel speed sensor 7 signal and the gear switch 8 signal, once the engine 14 speed is lower than the equivalent Wheel speed, no matter what position the throttle valve is in and whether the flameout switch 1 is on or not, the control unit 3 sends out control commands, and the control commands are sent to the air supplement solenoid valve 5 through the power amplifier 4, and the air supplement solenoid valve 5 Immediately open and supply air to the intake tee 9, and at the same time close the ignition switch on the igniter 16 to complete the engine flameout action to prevent the fuel from being ejected from the main oil passage or the idle oil passage of the carburetor 10; when the engine When the rotational speed signal sent by the rotational speed sensor 6 to the control unit 3 is zero, that is, when the engine stops rotating, the control unit 3 immediately sends a control command to the air supplement solenoid valve 5 to control the air supplement solenoid valve 5 to complete the power-off reset action.

The reduced wheel speed refers to the wheel speed multiplied by the gear ratio between the engine and the drive wheels.

The normal working mode of the engine: under the premise that the control working mode for preventing the fuel injection from the carburetor 10 when the engine is turned off and the control working mode for preventing the fuel injection from the carburetor 10 when the vehicle is coasting are not satisfied, the control unit 3 No control command is issued to the supplementary air solenoid valve 5, and the engine 14 is in a normal working state at this time.

In this specification, specific examples are used to illustrate the principles and implementations of the present invention, and the descriptions of the above embodiments are only used to help understand the method and the core idea of the present invention; There will be changes in the specific implementation manner and application scope of the idea of the invention. In conclusion, the contents of this specification should not be construed as limiting the present invention.

Claims (10)

1. The single cylinder carburetor type engine flameout and fuel cut-off control device is characterized in that: the device comprises an air supplementing assembly, a flameout switch (1), an idle speed contact switch (2), a control unit (3), an engine speed sensor (6), a driving wheel speed sensor (7) and a gear switch (8);

the air supplementing assembly comprises an air supplementing electromagnetic valve (5), an air filter (11), an air inlet three-way pipe (9), an engine (14), a carburetor (10) and an air supply hose (12), the left end port and the right end port of the air inlet three-way pipe (9) are respectively connected with a mixed gas pipe orifice between the carburetor (10) and the engine (14), and the upper end port of the air inlet three-way pipe (9) is connected with the air filter (11) through the air supply hose (12);

comprises an odometer, wherein a driving wheel speed sensor (7) is arranged at the odometer;

the generator (14) comprises an igniter (16), and the engine speed sensor (6) is arranged at the igniter (16);

the control unit (3) is respectively connected with the air supply electromagnetic valve (5), the flameout switch (1), the idle speed contact switch (2), the engine speed sensor (6), the driving wheel speed sensor (7) and the gear switch (8).

2. The single cylinder carburetor engine flameout and fuel cutoff control device according to claim 1, wherein: the air supply electromagnetic valve (5) is arranged on the air supply hose (12) close to the upper port of the air inlet three-way pipe (9).

3. A single cylinder carburetor type engine flameout and fuel-cut control device according to claim 2, characterized in that: the control unit (3) comprises a single chip microcomputer and a power amplifier (4), and the power amplifier (4) is connected with the air supply electromagnetic valve (5).

4. The single cylinder carburetor engine flameout and fuel cut control device of claim 2, wherein: the control unit (3) is respectively connected with the air supply electromagnetic valve (5), the flameout switch (1), the idling contact switch (2), the engine speed sensor (6), the driving wheel speed sensor (7) and the gear switch (8) through a first signal line, a second signal line, a third signal line, a fourth signal line, a fifth signal line and a sixth signal line.

5. The single cylinder carburetor engine flameout and fuel cut control device of claim 2, wherein: still include throttle and act as go-between (15), engine harness and throttle handle, install idle speed contact switch (2) on throttle is acted as go-between (15), the control unit (3) are installed on the engine harness, install flameout switch (1) throttle handle department.

6. The single cylinder carburetor engine flameout and fuel cutoff control device according to claim 1, wherein: the engine (14) comprises a transmission and a cylinder block, the engine rotation sensor (6) is mounted on the cylinder block, and the gear switch (8) is mounted in the transmission.

7. A single cylinder carburetor type engine flameout and fuel-cut control device according to claim 1, characterized in that: the engine rotating speed sensor (6) is a Hall sensor or a photoelectric rotating speed sensor or a capacitance type rotating speed sensor or a variable reluctance type rotating speed sensor.

8. The single cylinder carburetor engine flameout and fuel cutoff control device of claim 7, wherein: the photoelectric rotating speed sensor is a direct-emitting photoelectric rotating speed sensor or a reflective photoelectric rotating speed sensor or a projection photoelectric rotating speed sensor;

the capacitance type rotating speed sensor is an area change type capacitance type rotating speed sensor or a medium change type capacitance type rotating speed sensor;

the variable magnetic resistance type rotating speed sensor is an inductance type rotating speed sensor or a transformer type rotating speed sensor or an eddy current type rotating speed sensor.

9. A method for controlling the flameout and fuel cut of a single cylinder carburetor engine, the device for implementing the method comprising the device for controlling the flameout and fuel cut of the single cylinder carburetor engine according to any one of claims 1 to 8, wherein: the control system comprises a control working mode for preventing fuel from being sprayed out of a carburetor (10) when flameout occurs, a control working mode for preventing fuel from being sprayed out of the carburetor (10) when a vehicle slides, and a normal working mode of an engine;

-a control mode of operation preventing the fuel from being ejected from the carburetor (10) upon flame-out: the method comprises the steps that a flameout switch signal and an idle speed contact switch signal are respectively read through a flameout switch (1) and an idle speed contact switch (2) and are sent to a control unit (3), the control unit (3) judges whether a throttle valve is in a rapid closing state or whether the flameout switch (1) is in a connection state, if yes, the control unit (3) judges that an engine enters the flameout state and sends a control instruction, the control instruction is sent to an air supply electromagnetic valve (5) through a power amplifier (4), the air supply electromagnetic valve (5) is immediately opened and supplies air to an air inlet three-way pipe (9), the vacuum degree behind the throttle valve is reduced, and fuel oil is prevented from being sprayed out of an idle speed oil duct;

control mode of operation of the vehicle to prevent fuel injection from the carburetor (10) during coasting: control mode of operation of the vehicle to prevent fuel injection from the carburetor (10) during coasting: the control unit (3) continuously scans signals of an engine rotating speed sensor (6), a driving wheel speed sensor (7) and a gear switch (8), once the rotating speed of the engine (14) is lower than the speed of a folding wheel, no matter which position the throttle valve is located and whether the flameout switch (1) is in a connected state, the control unit (3) sends a control command, the control command is sent to the air supplementing electromagnetic valve (5) through the power amplifier (4), the air supplementing electromagnetic valve (5) is immediately opened and supplies air to the air inlet three-way pipe (9), and meanwhile, the ignition switch on the igniter (16) is closed to complete flameout of the engine, so that fuel oil is prevented from being sprayed out from a main oil duct or an idle oil duct of the carburetor (10); when the rotating speed signal sent by the engine rotating speed sensor (6) to the control unit (3) is zero, namely the engine stops rotating, the control unit (3) immediately sends a control instruction to the air replenishing electromagnetic valve (5) to control the air replenishing electromagnetic valve (5) to complete the power-off reset action;

and (3) normal working mode of the engine: on the premise that the control working mode for preventing fuel from being sprayed out of the carburetor (10) when flameout is not met and the control working mode for preventing fuel from being sprayed out of the carburetor (10) when the vehicle slides, the control unit (3) does not send any control instruction to the air replenishing electromagnetic valve (5), and the engine (14) is in a normal working state.

10. The single cylinder carburetor engine flameout and fuel cut control method according to claim 9, wherein: the folded wheel speed is the wheel speed multiplied by the gear ratio between the engine and the drive wheels.

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