Device for preventing stop tempering of hydrogen engine and protection method

Abstract

The invention discloses a device for preventing stop backfire of a hydrogen engine. The device comprises the hydrogen engine, and the hydrogen engine is provided with an air compressor, an air cylinder, a front air inlet pipe connected with the air cylinder, a throttle valve and a hydrogen injection valve which are arranged on the front air inlet pipe, and an exhaust pipe connected with the air cylinder. A throttle valve front pressure sensor and a throttle valve rear pressure sensor are arranged in front of and behind the throttle valve respectively, and an air compressor air outlet pipe of the air compressor is connected with a front air inlet pipe in front of the throttle valve. According to the device and the protection method for preventing the stop backfire of the hydrogen engine, the running state of the engine is monitored so that stop judgment can be conducted, meanwhile, the gas pressure difference value between the front portion and the rear portion of the throttle valve is monitored, and once the stop backfire risk exists, the stop protection mode is started immediately; by starting the air compressor and the time-delay relay, the engine is subjected to delayed flameout, engine scavenging work is carried out, and the problems of engine tempering and knocking caused by high residual hydrogen concentration when the hydrogen engine is shut down are solved.

Description

Technical Field

[0001] The invention relates to the technical field of hydrogen engines, and in particular to a device and a protection method for preventing a hydrogen engine from backfiring when it is shut down. Background Art

[0002] Hydrogen engines, as an engine that uses hydrogen as internal combustion fuel, have a similar working principle to traditional gasoline or diesel engines. They all generate power by burning a mixture of fuel and air in the cylinder, which drives the piston to move and then drives vehicles or mechanical equipment. Hydrogen produces only water after combustion, and does not emit carbon dioxide and other harmful gases, so it is considered an ideal clean energy source. This helps reduce greenhouse gas emissions and improve air quality. Hydrogen engines are highly efficient: hydrogen has a high combustion calorific value, and the energy released by the combustion of equal mass hydrogen is almost three times that of gasoline. This makes hydrogen engines theoretically have a higher thermal efficiency. The explosion limit of hydrogen refers to the lowest and highest concentration range of hydrogen that will explode when hydrogen is mixed with air (or oxygen) at a certain temperature and pressure to form a combustible gas mixture. When the concentration of hydrogen in this mixed gas reaches a certain range, it will encounter an ignition source such as an open flame or an electric spark and an explosion will occur. For hydrogen, its explosion limit (volume concentration) is usually 4.0% to 75.6%.

[0003] However, hydrogen is an extremely flammable and explosive gas. Due to the rapid diffusion of hydrogen flames and the rapid combustion process, flashback may occur. Flashback may not only damage engine components, but also cause fires or explosions. Especially after a hydrogen engine is stopped, if there is an excessively concentrated hydrogen mixture remaining in the intake duct, once the hydrogen leaks and reaches a certain concentration, the mixture may be ignited when encountering high-temperature exhaust gas or hot spots, causing flashback. Flashback may not only damage engine components, but also cause fires or explosions. Summary of the invention

[0004] The purpose of the present invention is to provide a device and a protection method for preventing hydrogen engine backfire when shut down, so as to solve the problem of engine backfire and knock caused by high residual hydrogen concentration when the hydrogen engine is shut down.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A device for preventing backfire when a hydrogen engine is stopped comprises a hydrogen engine, wherein the hydrogen engine is provided with an air compressor, a cylinder, a front intake pipe connected to the cylinder, a throttle valve and a hydrogen injection valve arranged on the front intake pipe, and an exhaust pipe connected to the cylinder; a pre-throttle pressure sensor and a post-throttle pressure sensor are respectively arranged before and after the throttle valve, and an air compressor outlet pipe of the air compressor is connected to the front intake pipe 2 in front of the throttle valve.

[0007] Preferably, an intake manifold temperature sensor is provided on the front intake pipe.

[0008] Preferably, a turbocharger is provided on the exhaust pipe.

[0009] Preferably, the exhaust pipe is divided into two parts: a pre-turbine exhaust pipe and a post-turbine exhaust pipe. The pre-turbine exhaust pipe is connected to the cylinder and the turbocharger, the post-turbine exhaust pipe is connected to the exhaust port of the turbocharger, and a post-turbine temperature sensor is provided on the post-turbine exhaust pipe.

[0010] Preferably, the air inlet of the compressor of the turbocharger is connected to the front air intake pipe of the turbine, the front air intake pipe of the turbine is provided with an intake temperature sensor, the exhaust port of the compressor is connected to the rear air intake pipe of the turbine, and the rear air intake pipe of the turbine is connected to the front air intake pipe.

[0011] Preferably, an intercooler is provided on the rear intake pipe of the turbine.

[0012] Preferably, the air inlet of the air compressor air inlet pipe of the air compressor is arranged away from the cylinder.

[0013] A method for preventing a hydrogen engine from backfiring when it is shut down according to any one of the above-mentioned devices comprises the following steps:

[0014] S1. When the engine is ready to stop, first make a stop judgment: if the engine start switch is turned off or the handbrake is pulled up, it is judged that the driver is ready to stop the engine. At the same time, if the engine speed is lower than the engine stop speed limit R, and the throttle opening is lower than the engine stop throttle opening limit SZ, it is judged that the engine is going to stop, and at the same time, the pressure difference measured by the throttle pre-pressure sensor and the throttle post-pressure sensor is monitored;

[0015] S2. When the pressure difference measured in step S1 is less than the pressure difference limit value P, the hydrogen engine shutdown protection mode is triggered, and the air compressor is started. After the air compressor is running, fresh high-pressure intake air enters the front intake pipe through the air compressor outlet pipe, and the delay relay is started at the same time, the engine is delayed shut down, and the engine scavenging work is performed, the purpose is to empty the residual hydrogen in the engine, reduce the temperature in the engine, and reduce the concentration of residual hydrogen in the engine;

[0016] S3. Determine whether the scavenging time exceeds the time limit T. If not, continue to run the parking protection mode. If exceeded, exit the parking protection mode and shut down the engine.

[0017] Preferably, the parking speed limit R is 200-350 r / min, the parking throttle opening limit SZ is 0.5-2%, the pressure difference limit P is 10-30 kPa, and the time limit T is 1-5 min.

[0018] Preferably, the parking speed limit R is 300 r / min, the parking throttle opening limit SZ is 1%, the pressure difference limit P is 20 kPa, and the time limit T is 3 min.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The present invention proposes a device and a protection method for preventing backfire when a hydrogen engine is shut down. The device monitors the running state of the engine and then makes a shutdown judgment. Meanwhile, a pre-throttle pressure sensor and a post-throttle pressure sensor are respectively arranged before and after the throttle to monitor the gas pressure difference before and after the throttle to diagnose the backfire when the hydrogen engine is shut down, and judge the risk of backfire when the engine is shut down. Once the risk of backfire when the engine is shut down is found, a shutdown protection mode is immediately started, and the engine is delayed by starting an air compressor and a delay relay to perform engine scavenging to exhaust residual hydrogen in the engine, reduce the temperature in the engine, and reduce the concentration of residual hydrogen in the engine at the same time, thereby solving the problems of engine backfire and knock caused by high residual hydrogen concentration when the hydrogen engine is shut down. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 A device for preventing backfire when a hydrogen engine stops and a working principle diagram of a hydrogen engine.

[0023] Description of reference numerals:

[0024] 1. Throttle valve; 11. Pressure sensor before throttle valve; 12. Pressure sensor after throttle valve;

[0025] 2. Front intake pipe; 21. Intake manifold temperature sensor;

[0026] 3. Hydrogen injection valve;

[0027] 4. Cylinder;

[0028] 5. Exhaust pipe before turbine;

[0029] 6. Turbocharger; 61. Compressor;

[0030] 7. Turbine front intake pipe; 71. Intake air temperature sensor;

[0031] 8. Turbine rear intake pipe; 81. Intercooler;

[0032] 9. Exhaust pipe after turbine; 91. Temperature sensor after turbine;

[0033] 10. Air compressor; 101. Air compressor air inlet pipe; 102. Air compressor air outlet pipe. DETAILED DESCRIPTION

[0034] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0035] like Figure 1 As shown, a device for preventing backfire when a hydrogen engine is stopped comprises a hydrogen engine, wherein the hydrogen engine is provided with an air compressor 10, a cylinder 4, a front intake pipe 2 connected to the cylinder 4, a throttle valve 1 and a hydrogen injection valve 3 arranged on the front intake pipe 2, and an exhaust pipe connected to the cylinder 4; a pre-throttle pressure sensor 11 and a post-throttle pressure sensor 12 are respectively arranged before and after the throttle valve 1, and an air compressor outlet pipe 102 of the air compressor 10 is connected to the front intake pipe 2 before the throttle valve 1.

[0036] Preferably, an intake manifold temperature sensor 21 is provided on the front intake pipe 2.

[0037] Preferably, a turbocharger 6 is provided on the exhaust pipe.

[0038] Preferably, the exhaust pipe is divided into two parts: a pre-turbine exhaust pipe 5 and a post-turbine exhaust pipe 9. The pre-turbine exhaust pipe 5 is connected to the cylinder 4 and the turbocharger 6, the post-turbine exhaust pipe 9 is connected to the exhaust port of the turbocharger 6, and the post-turbine exhaust pipe 9 is provided with a post-turbine temperature sensor 91.

[0039] Preferably, the air inlet of the compressor 61 of the turbocharger 6 is connected to the turbine front air intake pipe 7, and the turbine front air intake pipe 7 is provided with an intake temperature sensor 71. The exhaust port of the compressor 61 is connected to the turbine rear air intake pipe 8, and the turbine rear air intake pipe 8 is connected to the front air intake pipe 2.

[0040] Preferably, an intercooler 81 is provided on the turbine rear intake pipe 8 .

[0041] Preferably, the air inlet of the air compressor air inlet pipe 101 of the air compressor 10 is arranged away from the cylinder 4.

[0042] A method for preventing a hydrogen engine from backfiring when it is shut down according to any one of the above-mentioned devices comprises the following steps:

[0043] S1. When the engine is ready to stop, first make a stop judgment: if the engine start switch is turned off or the handbrake is pulled up, it is judged that the driver is ready to stop the engine. At the same time, if the engine speed is lower than the engine stop speed limit R, and the throttle opening is lower than the engine stop throttle opening limit SZ, it is judged that the engine is going to stop, and at the same time, the pressure difference measured by the throttle pre-pressure sensor 11 and the throttle post-pressure sensor 12 is monitored;

[0044] S2. When the pressure difference measured in step S1 is less than the pressure difference limit value P, the hydrogen engine shutdown protection mode is triggered, and the air compressor 10 is started. After the air compressor 10 is running, fresh high-pressure intake air enters the front intake pipe 2 through the air compressor outlet pipe 102, and the delay relay is started at the same time, the engine is delayed to shut down, and the engine scavenging work is performed, the purpose is to empty the residual hydrogen in the engine, reduce the temperature in the engine, and reduce the concentration of residual hydrogen in the engine;

[0045] S3. Determine whether the scavenging time exceeds the time limit T. If not, continue to run the parking protection mode. If exceeded, exit the parking protection mode and shut down the engine.

[0046] The acceptable range of the parking speed limit R is set to 200-350 r / min, the acceptable range of the parking throttle opening limit SZ is set to 0.5-2%, the acceptable range of the pressure difference limit P is set to 10-30 kPa, and the acceptable range of the time limit T is set to 1-5 min.

[0047] Preferably, the parking speed limit R is 300 r / min, the parking throttle opening limit SZ is 1%, the pressure difference limit P is 20 kPa, and the time limit T is 3 min.

[0048] The present invention proposes a device and a protection method for preventing the backfire of a hydrogen engine when it is shut down. The device monitors the running state of the engine and then makes a shutdown judgment. Meanwhile, a pre-throttle pressure sensor and a post-throttle pressure sensor are respectively arranged before and after the throttle to monitor the gas pressure difference before and after the throttle to diagnose the backfire of the hydrogen engine when it is shut down, and judge the risk of backfire when it is shut down. Once the risk of backfire is found, a shutdown protection mode is immediately started, and the engine is delayed by starting the air compressor and the delay relay to perform engine scavenging, thereby reducing the hydrogen content in the intake duct at the end of intake, exhausting the residual hydrogen in the engine, reducing the temperature in the engine, and reducing the concentration of the residual hydrogen in the engine, thereby solving the problems of engine backfire and knock caused by the high concentration of residual hydrogen when the hydrogen engine is shut down.

[0049] The above embodiments of the present invention are described in detail through examples, but the contents described are only exemplary embodiments of the embodiments of the present invention and cannot be considered to limit the scope of implementation of the embodiments of the present invention. The protection scope of the embodiments of the present invention is defined by the claims. Anyone who utilizes the technical solutions described in the embodiments of the present invention, or who, inspired by the technical solutions of the embodiments of the present invention, designs similar technical solutions within the essence and protection scope of the embodiments of the present invention to achieve the above technical effects, or who makes equal changes and improvements to the scope of application, shall still fall within the scope of protection covered by the patent of the embodiments of the present invention.

Claims

1. A device for preventing hydrogen engine from backfiring when it stops, characterized in that: The invention comprises a hydrogen engine, wherein the hydrogen engine is provided with an air compressor (10), a cylinder (4), a front intake pipe (2) connected to the cylinder (4), a throttle valve (1) and a hydrogen injection valve (3) arranged on the front intake pipe (2), and an exhaust pipe connected to the cylinder (4); a throttle valve front pressure sensor (11) and a throttle valve rear pressure sensor (12) are respectively arranged before and after the throttle valve (1), and an air compressor outlet pipe (102) of the air compressor (10) is connected to the front intake pipe (2) before the throttle valve (1).

2. The device for preventing hydrogen engine from backfiring when shut down according to claim 1, characterized in that: An intake manifold temperature sensor (21) is provided on the front intake pipe (2).

3. The device for preventing hydrogen engine from backfiring when shut down according to claim 1, characterized in that: The exhaust pipe is provided with a turbocharger (6).

4. The device for preventing hydrogen engine from backfiring when shut down according to claim 3, characterized in that: The exhaust pipe is divided into two parts: a turbine front exhaust pipe (5) and a turbine rear exhaust pipe (9); the turbine front exhaust pipe (5) is connected to the cylinder (4) and the turbocharger (6); the turbine rear exhaust pipe (9) is connected to the exhaust port of the turbocharger (6); and a turbine rear temperature sensor (91) is provided on the turbine rear exhaust pipe (9).

5. The device for preventing hydrogen engine from backfiring when shut down according to claim 4, characterized in that: The air inlet of the compressor (61) of the turbocharger (6) is connected to the turbine front air intake pipe (7), and the turbine front air intake pipe (7) is provided with an air intake temperature sensor (71); the exhaust port of the compressor (61) is connected to the turbine rear air intake pipe (8), and the turbine rear air intake pipe (8) is connected to the front air intake pipe (2).

6. The device for preventing hydrogen engine from backfiring when shut down according to claim 5, characterized in that: An intercooler (81) is provided on the turbine rear air intake pipe (8).

7. The device for preventing hydrogen engine from backfiring when shut down according to claim 1, characterized in that: The air inlet of the air compressor air inlet pipe (101) of the air compressor (10) is arranged away from the cylinder (4).

8. A method for preventing hydrogen engine from backfiring when shutting down according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1. When the engine is ready to stop, firstly, a stop judgment is made: if the engine start switch is turned off or the handbrake is pulled up, it is judged that the driver is ready to stop the engine; and if the engine speed is lower than the engine stop speed limit R, and the throttle opening is lower than the engine stop throttle opening limit SZ, then it is judged that the engine is to stop, and at the same time, the pressure difference measured by the throttle pre-pressure sensor (11) and the throttle post-pressure sensor (12) is monitored; S2. When the pressure difference value measured in step S1 is less than the pressure difference limit value P, the hydrogen engine shutdown protection mode is triggered, the air compressor (10) is started, and the delay relay is started at the same time, the engine is delayed shut down, and the engine scavenging work is performed; S3. Determine whether the scavenging time exceeds the time limit T. If not, continue to run the parking protection mode. If exceeded, exit the parking protection mode and shut down the engine.

9. The method for preventing hydrogen engine from backfire during shutdown according to claim 8, characterized in that: The parking speed limit R is 200-350 r / min, the parking throttle opening limit SZ is 0.5-2%, the pressure difference limit P is 10-30 kPa, and the time limit T is 1-5 min.

10. The method for preventing hydrogen engine from backfire during shutdown according to claim 9, characterized in that: The parking speed limit R is 300r / min, the parking throttle opening limit SZ is 1%, the pressure difference limit P is 20kpa, and the time limit T is 3min.

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