阅读说明：本技术 低压燃气增压发动机运行模式切换装置及其切换控制方法 (Low-pressure gas supercharged engine running mode switching device and switching control method thereof ) 是由 唐行辉 于 2019-10-17 设计创作，主要内容包括：本发明公开了一种低压燃气增压发动机运行模式切换装置,包括安装在发动机本体上的进气歧管和排气管,进气歧管连接有进气管和依次安装的空气滤清器、增压器、中冷器和电子节气门,还包括低压燃气管,低压燃气管上并联有启动模式燃气输送装置和工作模式燃气输送装置,电子节气门、启动模式燃气输送装置和工作模式燃气输送装置连接有运行模式切换控制装置,还公开了该装置的切换控制方法；在启动运行模式下,混合气体不经过增压器和中冷器,缩短了混合气体的行进长度,使发动机的启动时间大大缩短,使启动性能提高；进入工作运行模式后,发动机进气可增压,适合于高功率运行,实现了发动机自吸式和增压式的混合使用,提高了发动机的运行性能。(The invention discloses a low-pressure gas supercharged engine operation mode switching device, which comprises an air inlet manifold and an exhaust pipe which are arranged on an engine body, wherein the air inlet manifold is connected with an air inlet pipe, an air filter, a supercharger, an intercooler and an electronic throttle valve which are sequentially arranged; in the starting operation mode, the mixed gas does not pass through the supercharger and the intercooler, the advancing length of the mixed gas is shortened, the starting time of the engine is greatly shortened, and the starting performance is improved; after the engine enters the working operation mode, the air inlet of the engine can be pressurized, the engine is suitable for high-power operation, the self-suction type and the pressurization type hybrid use of the engine is realized, and the operation performance of the engine is improved.)

1. Low pressure gas supercharged engine operating mode auto-change over device, including installing air intake manifold and the blast pipe on the engine body, air intake manifold is connected with the intake pipe, install air cleaner, booster, intercooler and electronic throttle valve, its characterized in that along gas advancing direction in proper order in the intake pipe: still include the low pressure gas pipe, the low pressure gas union coupling has start mode gas conveyor, start mode gas conveyor's the end of giving vent to anger is connected the intercooler with between the electronic throttle valve in the intake pipe, on the low pressure gas pipe with start mode gas conveyor connects in parallel and is provided with mode gas conveyor, mode gas conveyor's the end of giving vent to anger is connected air cleaner with between the booster in the intake pipe, still include operation mode switching control device, the electronic throttle valve start mode gas conveyor with mode gas conveyor is connected to respectively operation mode switching control device.

2. The low-pressure gas supercharged engine operating mode switching device according to claim 1, characterized in that: the running mode switching control device comprises an electronic control unit ECU, a rotating speed sensor arranged on the engine body and an oxygen sensor arranged on the exhaust pipe, wherein the rotating speed sensor and the oxygen sensor are respectively connected to the electronic control unit ECU.

3. The low-pressure gas supercharged engine operating mode switching device according to claim 2, characterized in that: the starting mode gas conveying device comprises a starting mode gas conveying pipe, a starting mode gas conveying valve, a check valve and a starting mode gas mixer are sequentially installed on the starting mode gas conveying pipe along the gas advancing direction, the starting mode gas mixer is installed in series on the air inlet pipe between the intercooler and the electronic throttle valve, and the starting mode gas conveying valve is connected to the electronic control unit ECU.

4. The low-pressure gas supercharged engine operating mode switching device according to claim 3, characterized in that: working mode gas conveyor includes working mode gas conveyer pipe, install working mode gas delivery valve and working mode gas blender along gas advancing direction in proper order on the working mode gas conveyer pipe, the working mode gas blender is established ties and is installed air cleaner with between the booster on the intake pipe, working mode gas delivery valve is connected to automatically controlled unit ECU.

5. The low-pressure gas supercharged engine operating mode switching device according to claim 4, characterized in that: the starting mode gas delivery valve and the working mode gas delivery valve are respectively set to be electromagnetic valves.

6. The switching control method of the low-pressure gas supercharged engine operating mode switching device according to claim 5, characterized in that: comprises the following steps of (a) carrying out,

step one, presetting a mixed gas calibration concentration, an opening rate of a starting mode gas delivery valve when an engine is started and an opening rate of an electronic throttle valve in an Electronic Control Unit (ECU);

secondly, starting the engine through the electronic control unit ECU, and entering a starting running mode;

in a starting running mode, the electronic control unit ECU receives a detection signal of the rotating speed sensor in real time, controls the working mode gas delivery valve to be closed and controls the starting mode gas delivery valve and the electronic throttle valve to be opened according to a set opening rate in the process that the engine is started to be in an idle running state, and controls the engine to be in the idle running state;

in the process of starting the engine and keeping idle running, the oxygen sensor starts self-checking and enters normal closed-loop work, namely, the content of oxygen ions in the exhaust pipe is collected in real time and a detection signal is transmitted to the electronic control unit ECU, the electronic control unit ECU calculates the concentration of mixed gas according to the detection signal to form gas closed-loop control, and finally the opening degree of the starting mode gas transmission valve under the running of the engine in the idle state is determined;

after the oxygen sensor enters closed-loop work, the electric control unit ECU controls the working mode gas delivery valve to be opened at a rate of M% per second, the starting mode gas delivery valve keeps the current opening degree unchanged in the opening process of the working mode gas delivery valve controlled by the electric control unit ECU, and the electric control unit ECU receives a detection signal of the oxygen sensor in real time;

fifthly, the electronic control unit ECU receives the detection signal of the oxygen sensor, processes the detection signal to obtain the detection concentration of the mixed gas, and processes and compares the detection concentration with the calibration concentration of the mixed gas in the electronic control unit ECU;

when the electronic control unit ECU judges that the detected concentration of the mixed gas is higher than the calibrated concentration of the mixed gas and the rising concentration is more than or equal to N%, the electronic control unit ECU controls the working mode gas delivery valve to be opened at a rate of M% per second continuously, and meanwhile, the electronic control unit ECU controls the opening degree of the starting mode gas delivery valve to be reduced according to the closed-loop work of the oxygen sensor;

when the electronic control unit ECU determines that the detected concentration of the mixed gas is higher than the calibrated concentration of the mixed gas and the concentration of the raised concentration is less than N%, returning to the fourth step;

the control process of the step is carried out until the opening degree of the starting mode gas delivery valve is zero, and then the next step is carried out;

step six, the electronic control unit ECU detects that the opening degree of the starting mode gas delivery valve is zero, namely the starting mode gas delivery valve is completely closed, the electronic control unit ECU controls the starting mode gas delivery valve to be continuously closed, and simultaneously controls the working mode gas delivery valve to stop continuously opening, and the engine is switched to a working running mode;

after the engine is switched into a working operation mode, the ECU enters PID fine adjustment control according to a detection signal of the oxygen sensor, and the gas delivery valve in the working mode is regulated according to the actual operation state of the engine, and the engine can work with load in the mode.

7. The switching control method of the low-pressure gas supercharged engine operating mode switching device according to claim 6, characterized in that: m and N are set values respectively, wherein M is more than 0.5 and less than 2; n is more than or equal to 5 and less than or equal to 10.

Technical Field

The invention relates to the technical field of natural gas engine control, in particular to a low-pressure gas supercharged engine running mode switching device and a specific switching control method used by the switching device.

Background

Gas engines using low-pressure gas sources such as biogas, pipeline gas, gas and the like as fuels have been widely used in power generator stations, petrochemical industry, breeding industry and other industries due to their energy-saving and environmental-friendly properties of operation, and low-pressure gas engines are classified into self-priming low-pressure gas engines and low-pressure gas supercharged engines. The self-suction low-pressure gas engine has better starting performance, but because the air inlet system is not provided with a supercharger, the pressure of the air inlet pipe is lower, so that the power of the engine is lower, and the power supply requirement of a high-power electric appliance cannot be met; although the supercharger is arranged on the low-pressure gas supercharged engine, the power consumption requirement of a high-power electric appliance is met, when the low-pressure gas supercharged engine is used, gas can flow into a cylinder to do work through a series of pipelines such as a mixed gas pipeline, the supercharger, an intercooler and an air inlet manifold, the gas supply pipeline is overlong in arrangement, the defect that the starting time of the low-pressure gas supercharged engine is long is easily caused, the phenomenon of difficulty in starting can even occur when a starting control strategy is not good, and in addition, the engine is influenced by the running environment of the engine and sometimes even needs to be continuously started for multiple times, so that the engine.

Disclosure of Invention

The invention aims to solve the technical problem of providing a low-pressure gas supercharged engine running mode switching device which can realize the automatic switching between a self-priming mode and a supercharging mode of an engine and can synchronously improve the starting performance of the engine.

In order to solve the technical problems, the technical scheme of the invention is as follows: low pressure gas supercharged engine operating mode auto-change over device, including installing air intake manifold and blast pipe on the engine body, air intake manifold is connected with the intake pipe, install air cleaner, booster, intercooler and electronic throttle valve in proper order along gaseous advancing direction in the intake pipe, still include the low pressure gas pipe, the low pressure gas union coupling has start mode gas conveyor, start mode gas conveyor's the end of giving vent to anger is connected the intercooler with between the electronic throttle valve in the intake pipe, on the low pressure gas pipe with start mode gas conveyor connects in parallel and is provided with operating mode gas conveyor, operating mode gas conveyor's the end of giving vent to anger is connected air cleaner with between the booster in the intake pipe, still include operating mode switching controlling means, electronic throttle valve, air throttle valve, The starting mode gas conveying device and the working mode gas conveying device are respectively connected to the operation mode switching control device.

As a preferable technical solution, the operation mode switching control device includes an electronic control unit ECU, a rotation speed sensor provided on the engine body, and an oxygen sensor mounted on the exhaust pipe, and the rotation speed sensor and the oxygen sensor are respectively connected to the electronic control unit ECU.

As a preferable technical scheme, the start-up mode gas delivery device includes a start-up mode gas delivery pipe, a start-up mode gas delivery valve, a check valve, and a start-up mode gas mixer are sequentially installed on the start-up mode gas delivery pipe along a gas advancing direction, the start-up mode gas mixer is installed in series on the intake pipe between the intercooler and the electronic throttle valve, and the start-up mode gas delivery valve is connected to the electronic control unit ECU.

As the preferred technical scheme, the working mode gas conveying device comprises a working mode gas conveying pipe, a working mode gas conveying valve and a working mode gas mixer are sequentially installed on the working mode gas conveying pipe along the gas advancing direction, the working mode gas mixer is installed in series on the air filter and the air inlet pipe between the superchargers, and the working mode gas conveying valve is connected to the electronic control unit ECU.

As a preferred technical solution, the start mode gas delivery valve and the operation mode gas delivery valve are respectively provided as electromagnetic valves.

The invention also provides a switching control method of the low-pressure gas supercharged engine running mode switching device, which comprises the following steps,

step one, presetting a mixed gas calibration concentration, an opening rate of a starting mode gas delivery valve when an engine is started and an opening rate of an electronic throttle valve in an Electronic Control Unit (ECU);

secondly, starting the engine through the electronic control unit ECU, and entering a starting running mode;

in a starting running mode, the electronic control unit ECU receives a detection signal of the rotating speed sensor in real time, controls the working mode gas delivery valve to be closed and controls the starting mode gas delivery valve and the electronic throttle valve to be opened according to a set opening rate in the process that the engine is started to be in an idle running state, and controls the engine to be in the idle running state;

in the process of starting the engine and keeping idle running, the oxygen sensor starts self-checking and enters normal closed-loop work, namely, the content of oxygen ions in the exhaust pipe is collected in real time and a detection signal is transmitted to the electronic control unit ECU, the electronic control unit ECU calculates the concentration of mixed gas according to the detection signal to form gas closed-loop control, and finally the opening degree of the starting mode gas transmission valve under the running of the engine in the idle state is determined;

after the oxygen sensor enters closed-loop work, the electric control unit ECU controls the working mode gas delivery valve to be opened at a rate of M% per second, the starting mode gas delivery valve keeps the current opening degree unchanged in the opening process of the working mode gas delivery valve controlled by the electric control unit ECU, and the electric control unit ECU receives a detection signal of the oxygen sensor in real time;

fifthly, the electronic control unit ECU receives the detection signal of the oxygen sensor, processes the detection signal to obtain the detection concentration of the mixed gas, and processes and compares the detection concentration with the calibration concentration of the mixed gas in the electronic control unit ECU;

when the electronic control unit ECU judges that the detected concentration of the mixed gas is higher than the calibrated concentration of the mixed gas and the rising concentration is more than or equal to N%, the electronic control unit ECU controls the working mode gas delivery valve to be opened at a rate of M% per second continuously, and meanwhile, the electronic control unit ECU controls the opening degree of the starting mode gas delivery valve to be reduced according to the closed-loop work of the oxygen sensor;

when the electronic control unit ECU determines that the detected concentration of the mixed gas is higher than the calibrated concentration of the mixed gas and the concentration of the raised concentration is less than N%, returning to the fourth step;

the control process of the step is carried out until the opening degree of the starting mode gas delivery valve is zero, and then the next step is carried out;

step six, the electronic control unit ECU detects that the opening degree of the starting mode gas delivery valve is zero, namely the starting mode gas delivery valve is completely closed, the electronic control unit ECU controls the starting mode gas delivery valve to be continuously closed, and simultaneously controls the working mode gas delivery valve to stop continuously opening, and the engine is switched to a working running mode;

after the engine is switched into a working operation mode, the ECU enters PID fine adjustment control according to a detection signal of the oxygen sensor, and the gas delivery valve in the working mode is regulated according to the actual operation state of the engine, and the engine can work with load in the mode.

As an improvement to the technical scheme, M and N are set values respectively, wherein M is more than 0.5 and less than 2; n is more than or equal to 5 and less than or equal to 10.

Due to the adoption of the technical scheme, the invention has the following beneficial effects: when the engine is started, the natural gas is conveyed into the air inlet pipe by using the starting mode gas conveying device, after the engine is started and normally operates, the natural gas is conveyed into the air inlet pipe by using the working mode gas conveying device, and the automatic switching between the starting operation mode and the working operation mode is realized by using the operation mode switching control device; in the starting operation mode, the mixed gas does not pass through the supercharger and the intercooler, the advancing length of the mixed gas is shortened, the starting time of the engine is greatly shortened, and the starting performance is improved; after the engine enters the working operation mode, the air inlet of the engine can be pressurized, the engine is suitable for high-power operation, the self-suction type and the pressurization type hybrid use of the engine is realized, and the operation performance of the engine is improved.

Drawings

The drawings are only for purposes of illustrating and explaining the present invention and are not to be construed as limiting the scope of the present invention. Wherein:

FIG. 1 is a schematic diagram of the gas delivery and configuration of an engine start-up mode of operation according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of the gas delivery and configuration of an engine operating mode according to an embodiment of the present invention;

FIG. 3 is a control process flow diagram of an embodiment of the present invention;

in the figure: 1-an engine block; 2-an intake manifold; 3-an exhaust pipe; 4, an air inlet pipe; 5-an air filter; 6-a supercharger; 7-an intercooler; 8-electronic throttle valve; 9-low pressure gas pipe; 10-a rotational speed sensor; 11-an oxygen sensor; 12-an electronic control unit ECU; 13-starting mode gas delivery pipe; 14-start mode gas delivery valve; 15-a one-way valve; 16-start mode gas mixer; 17-working mode gas delivery pipe; 18-working mode gas delivery valve; 19-working mode gas mixer.

Detailed Description

The invention is further illustrated below with reference to the figures and examples. In the following detailed description, certain exemplary embodiments of the present invention are described by way of illustration only. Needless to say, a person skilled in the art realizes that the described embodiments can be modified in various different ways without departing from the spirit and scope of the present invention. Accordingly, the drawings and description are illustrative in nature and not intended to limit the scope of the claims.

As shown in fig. 1 and 2, the low-pressure gas supercharged engine operation mode switching device includes an intake manifold 2 and an exhaust pipe 3 which are mounted on an engine body 1, the intake manifold 2 is connected with an intake pipe 4, and an air cleaner 5, a supercharger 6, an intercooler 7 and an electronic throttle valve 8 are sequentially mounted on the intake pipe 4 along a gas advancing direction, and are used for conveying gas to the engine body 1 so as to enable the engine body 1 to operate. This embodiment still includes low pressure gas pipe 9, low pressure gas pipe 9 is connected with start mode gas conveyor, start mode gas conveyor's the end of giving vent to anger is connected intercooler 7 with between the electronic throttle valve 8 on the intake pipe 4, on the low pressure gas pipe 9 with start mode gas conveyor connects in parallel and is provided with mode gas conveyor, mode gas conveyor's the end of giving vent to anger is connected air cleaner 5 with between the booster 6 on the intake pipe 4. The starting mode gas conveying device conveys natural gas into the gas inlet pipe 4 in a starting operation mode, and the working mode gas conveying device conveys natural gas into the gas inlet pipe 4 in a working operation mode, so that the natural gas is conveyed by respectively selecting corresponding gas supply channels according to different operation modes, and the gas utilization control of the engine in different operation states is met.

The present embodiment is further provided with an operation mode switching control device, and the electronic throttle valve 8, the start mode gas delivery device, and the operation mode gas delivery device are respectively connected to the operation mode switching control device. Aiming at the running state of the engine, the natural gas is conveyed to the engine by the starting mode gas conveying device or the working mode gas conveying device under the control of the running mode switching control device, the conveying of the natural gas can be controlled to be automatically switched from the conveying of the starting mode gas conveying device to the conveying of the working mode gas conveying device, no manual intervention is needed in the control switching process, and the use is flexible and convenient.

Wherein the operation mode switching control device includes an electronic control unit ECU12, a rotation speed sensor 10 provided on the engine body 1, and an oxygen sensor 11 mounted on the exhaust pipe 3, the rotation speed sensor 10 and the oxygen sensor 11 being connected to the electronic control unit ECU12, respectively. The oxygen sensor 11 is used for detecting the content of oxygen in the exhaust gas in the exhaust pipe 3, and transmitting a detection signal to the electronic control unit ECU12, and after the processing of the electronic control unit ECU12, the closed-loop control of the engine is realized. The rotation speed sensor 10 is used for detecting the rotation speed of the engine and transmitting a rotation speed signal to the electronic control unit ECU12, and the electronic control unit ECU12 determines that the engine is in a starting state, an idling state or a normal running state according to the rotation speed signal.

The start mode gas conveying device comprises a start mode gas conveying pipe 13, a start mode gas conveying valve 14, a check valve 15 and a start mode gas mixer 16 are sequentially installed on the start mode gas conveying pipe 13 along the gas advancing direction, the start mode gas mixer 16 is installed on the gas inlet pipe 4 between the intercooler 7 and the electronic throttle valve 8 in series, and the start mode gas conveying valve 14 is connected to the electronic control unit ECU 12. When the engine is started, the electronic control unit ECU12 controls natural gas to enter the start mode gas mixer 16, the natural gas and the air are mixed to form a gas mixture and are rapidly sucked into the intake manifold 2 to do work to start the engine, the natural gas or the mixed gas does not need to pass through the supercharger 6 and the intercooler 7, the engine is started by self-suction, the stroke of the gas mixture in the intake pipe 4 is shortened, the start time is greatly shortened, and the start performance of the engine is improved.

And the mode gas conveyor includes mode gas conveyer pipe 17, mode gas conveyer valve 18 and mode gas blender 19 are installed along gas advancing direction in proper order on the mode gas conveyer pipe 17 of work, mode gas blender 19 is installed in series the air cleaner 5 with between the booster 6 on the intake pipe 4, mode gas conveyer valve 18 is connected to electrical unit ECU 12. After the engine is started, the electronic control unit ECU12 controls natural gas to enter the working mode gas mixer 19, and the natural gas and air are mixed to form a mixed gas, and the mixed gas passes through the supercharger 6 and the intercooler 7 and then enters the engine to do work, so that the engine can be used under high power and large load. And the starting mode gas delivery valve 14 and the working mode gas delivery valve 18 are respectively set as electromagnetic valves so as to be in signal connection with the electronic control unit ECU12, so that real-time online control is realized through the electronic control unit ECU12, and the opening states or the opening degrees of the two valve bodies are adjusted in time according to the actual running condition of the engine.

As shown in fig. 3, the present invention further provides a switching control method of the above low-pressure gas supercharged engine operation mode switching device, which is used for automatically switching the engine from the start operation mode to the working operation mode, and specifically includes the following steps:

step one, presetting a mixture gas calibration concentration, an opening rate of the start mode gas delivery valve 14 and an opening rate of the electronic throttle valve 8 when the engine is started in the electronic control unit ECU12 so as to realize the working condition control of the engine in a start running mode or a working running mode.

And step two, starting the engine through the electronic control unit ECU12, and entering a starting running mode. In the starting running mode, the ECU12 receives the detection signal of the rotation speed sensor 10 in real time, and in the process of the engine starting to the idle state, the ECU12 controls the working mode gas delivery valve 18 to close, and controls the starting mode gas delivery valve 14 and the electronic throttle valve 8 to open according to the set opening rate until the engine enters the idle running state. The ECU12 can determine whether the engine is in a starting process, an idling process or a normal operation process according to the signal detected by the rotation speed sensor 10, and the specific determination process is well known to those skilled in the art and will not be described in detail herein.

And step three, in the process of starting the engine and keeping the engine in idle running, the oxygen sensor 11 starts self-checking and enters normal closed-loop work, namely, the content of oxygen ions in the exhaust pipe 3 is collected in real time, a detection signal is transmitted to the electronic control unit ECU12, the ECU12 calculates the concentration of the mixed gas according to the detection signal to form gas closed-loop control, and finally the opening degree of the starting mode gas delivery valve 14 in the idle running state of the engine is determined. The self-test and closed-loop operation of the oxygen sensor 11 is well known to those skilled in the art.

After the oxygen sensor 11 enters the closed-loop operation, the electronic control unit ECU12 controls the operation mode gas delivery valve 18 to be slowly opened at a rate of M% per second, and in the process that the electronic control unit ECU12 controls the operation mode gas delivery valve 18 to be opened, the start mode gas delivery valve 14 keeps the current opening degree unchanged, and the electronic control unit ECU12 receives the detection signal of the oxygen sensor 11 in real time. Wherein M is a set value, and M is greater than 0.5 and less than 2, the smaller the value of M, the longer the switching mode time required for switching from the start-up mode gas delivery valve 14 to the operation mode gas delivery valve 18 for delivering the natural gas, but the more stable the switching process, otherwise, the larger the value of M, the shorter the switching time required, and the relatively unstable the switching process.

And step five, the electronic control unit ECU12 receives the detection signal of the oxygen sensor 11, processes the detection signal to obtain the detection concentration of the mixed gas, and processes and compares the detection concentration with the calibration concentration of the mixed gas in the electronic control unit ECU 12. Specifically, when the ECU12 determines that the detected concentration of the mixed gas is higher than the calibrated concentration of the mixed gas and the raised concentration is greater than or equal to N%, the ECU12 controls the valve to open the operation mode gas delivery valve 18 at a rate of M% per second, and simultaneously the ECU12 controls the opening degree of the start mode gas delivery valve 14 to decrease according to the closed-loop operation of the oxygen sensor 11; when the ECU12 determines that the detected concentration of the mixture gas is higher than the nominal concentration of the mixture gas by a concentration of < N%, the process returns to step four.

Wherein N is a set value, N is more than or equal to 5 and less than or equal to 10, for example, N is set to be 5. When the ECU12 determines that the detected concentration of the mixed gas is higher than the calibrated concentration of the mixed gas and the raised concentration is more than or equal to 5%, the ECU12 controls the valve to open the working mode gas delivery valve 18 at a rate of M% per second, and simultaneously the ECU12 controls the opening degree of the starting mode gas delivery valve 14 to decrease according to the closed-loop work of the oxygen sensor 11; when the ECU12 determines that the detected concentration of the mixed gas is higher than the calibrated concentration of the mixed gas and the raised concentration is less than 5%, the ECU12 also controls the operation mode gas delivery valve 18 to be slowly opened at a rate of M% per second, but at this time, the start mode gas delivery valve 14 keeps the current opening constant until the detected concentration of the mixed gas is higher than the calibrated concentration of the mixed gas and the raised concentration is greater than or equal to 5%, and the start mode gas delivery valve 14 gradually decreases the opening again under the control of the ECU12 until the opening of the start mode gas delivery valve 14 is zero, and the next step is performed.

In the cooperation of the fourth step and the fifth step, the opening degree of the operation mode gas delivery valve 18 is continuously increased, more and more gas flows into the engine through the operation mode gas delivery valve 18, and in order to maintain the concentration of the final mixture gas entering the intake manifold 2 to be the set concentration in the ECU, the opening degree of the start mode gas delivery valve 14 is gradually decreased under the feedback regulation of the oxygen sensor 11 until the start mode gas delivery valve is completely closed.

Step six, the electronic control unit ECU12 detects that the opening degree of the start-up mode gas delivery valve 14 is zero, that is, the start-up mode gas delivery valve 14 is completely closed, the electronic control unit ECU12 controls the start-up mode gas delivery valve 14 to be continuously closed, and controls the working mode gas delivery valve 18 to stop opening continuously, so that the engine is switched to the working operation mode. After the engine is switched into a working operation mode, the electronic control unit ECU12 enters PID fine adjustment control according to the detection signal of the oxygen sensor 11, and regulates and controls the gas delivery valve 18 in the working mode according to the actual operation state of the engine, and in this mode, the engine can work with load. After the engine is switched to a normal supercharging working operation mode from a starting operation mode, the engine can work with load. When the engine is in a working operation mode, the starting mode gas delivery valve 14 is always closed, and because the check valve 15 is arranged on the serial branch, the gas mixture with relatively high pressure after pressurization can be prevented from flowing back to enter the low-pressure gas pipe 9, and the safe operation of the engine is ensured.

When the engine is started, the natural gas is conveyed into the air inlet pipe 4 by using the starting mode gas conveying device, after the engine is started and normally operates, the natural gas is conveyed into the air inlet pipe 4 by using the working mode gas conveying device, and the automatic switching between the starting operation mode and the working operation mode is realized by using the operation mode switching control device; in the starting operation mode, the mixed gas does not pass through the supercharger 6 and the intercooler 7, the advancing length of the mixed gas is shortened, the starting time of the engine is greatly shortened, and the starting performance is improved; after the engine enters the working operation mode, the air inlet of the engine can be pressurized, the engine is suitable for high-power operation, the self-suction type and the pressurization type hybrid use of the engine is realized, and the operation performance of the engine is improved.

The foregoing shows and describes the general principles, essential features, and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.