Ignition and cold start control system applied to pure ammonia engine

Abstract

The ignition and cold start control system comprises a liquid ammonia bottle, an electric control intercooler, a throttle valve, an electric drive assembly and an electric control supercharger, an output port of the liquid ammonia bottle is connected with the input end of an ammonia liquid evaporator, the output end of the ammonia liquid evaporator is connected with one end of an engine ejector, and the other end of the engine ejector is connected with an ignition device. The other end of the engine ejector is communicated with a connector at one end of the engine intake manifold, fresh air is communicated with a connector at the other end of the electric control intercooler through the electric control supercharger, the other end of an outlet of the electric control intercooler is connected with the throttle valve, and an output port of the throttle valve is connected with a connector at one end of the engine intake manifold. According to the method, the inlet amount of the ammonia gas can be accurately controlled, so that the ammonia gas is combusted more sufficiently, more energy is provided for the engine, a high-reliability and low-emission solution is provided for the ammonia gas engine, and the method is suitable for heavy-load scenes such as commercial vehicles and ships.

Description

Technical Field

[0001] This invention relates to the field of pure ammonia engine technology, and in particular to an ignition and cold start control system for pure ammonia engines. Background Technology

[0002] An NH3 engine is an internal combustion engine that uses ammonia (NH3) as fuel. Its combustion products are only nitrogen and water, making it a potential zero-carbon emission alternative to traditional fuel engines. The following are its core technological characteristics, current applications, and challenges: Ammonia has a high auto-ignition temperature (530℃) and a slow combustion speed (laminar flame speed is only 1 / 5 that of gasoline). This makes ammonia ignition extremely difficult, and traditional spark plug ignition systems are insufficient. Special ignition technologies are required, and breakthroughs in combustion control technology are needed. Furthermore, emission control technologies are also crucial for pure ammonia engines, as they produce NOx and NH3 emissions.

[0003] Existing technologies: Plasma ignition technology is one of the most promising solutions. It uses high-temperature and reactive particles released by high-energy plasma to directly break down the chemical stability of ammonia, achieving ignition. This can reduce the ignition temperature to below 600℃, with a success rate as high as 99.9%, far exceeding the 85% of traditional ignition technologies. Ignition fuel technology is another commonly used solution, using a small amount of highly reactive fuel (such as diesel, hydrogen, or natural gas) as an ignition source. The high reactivity of the ignition fuel promotes the combustion of ammonia. Studies have shown that using 5% ignition diesel fuel can achieve stable combustion of ammonia.

[0004] Emission control in ammonia engines is primarily achieved through a two-stage SCR (Selective Catalytic Reduction) system. The first-stage SCR-ASC (Ammonia Slip Catalyst) treats the initial NO₂. x To control NH3 emissions, an ammonia sensor monitors the ammonia concentration in the exhaust gas in real time and dynamically adjusts the ammonia injection rate; the downstream SCR-ASC acts as a second line of defense, further reducing NO. x And NH3 emissions, ensuring that emissions meet standards.

[0005] Current aftertreatment solutions for ammonia engines cannot cover the applications of spark-ignition engines. Spark-ignition engines have higher exhaust temperatures and poorly controlled ammonia-to-air flow ratios, resulting in low combustion efficiency, resource waste, and insufficient oxygen concentration. Existing aftertreatment systems cannot completely reduce and convert NO. x And NH3. Summary of the Invention

[0006] In view of the above problems, the present invention provides an ignition and cold start control system for pure ammonia engines. It can not only accurately control the amount of ammonia entering, so that the ammonia can burn more completely and provide more energy to the engine, but also provide a highly reliable and low-emission solution for ammonia engines, which is suitable for heavy-duty scenarios such as commercial vehicles and ships.

[0007] To achieve the above and other related objectives, the present invention provides the following technical solution: A ignition and cold start control system for a pure ammonia engine includes a liquid ammonia cylinder, an electronically controlled intercooler, a throttle valve, an electric drive assembly, and an electronically controlled turbocharger. The outlet of the liquid ammonia cylinder is connected to the input of an ammonia evaporator. The outlet of the ammonia evaporator is connected to one end of an engine injector. The other end of the engine injector is connected to one end of the engine intake manifold. Fresh air passes through the electronically controlled turbocharger and connects to the other end of the electronically controlled intercooler. The other end of the outlet of the electronically controlled intercooler is connected to the throttle valve. The outlet of the throttle valve is connected to one end of the engine intake manifold. The coolant of the electronically controlled turbocharger is connected to the engine coolant and the electric drive assembly coolant via electronically controlled valves. The other end of the ignition engine is connected to a catalytic converter.

[0008] Furthermore, the internal emission control of the spark-ignition engine first involves lean-burn control, expanding the air-fuel ratio of the spark-ignition engine from the traditional 1.0-1.2 to >1.5. This is achieved by increasing the intake air volume and reducing the combustion temperature, thereby reducing NO. x The generation of NOx also leaves an excess of oxygen in the cylinder, providing a basis for the aftertreatment system to process NOx. x It provides conditions for the redox reaction of NH3.

[0009] Furthermore, the ignition angle of the spark-ignition engine is controlled at an ignition angle of >34-36 degrees. When the knock intensity / knock limit is >0.7-0.9, the target ignition angle of the spark-ignition engine is processed at -1.5-2.2 degrees. When the knock intensity / knock limit is <0.3-0.5, the ignition angle of the spark-ignition engine is set according to the target. The knock intensity and knock limit are read by the controller of the spark-ignition engine.

[0010] Furthermore, the in-engine emission control of the spark-ignition engine employs secondary ammonia injection control, dividing the required ammonia injection quantity into two equal injections. The interval angle between the two injections can be 200 degrees crankshaft angle, 220 degrees, or 240 degrees. The vehicle controller, through adaptive control, selects the optimal injection interval angle, and the optimal boundary is the engine speed fluctuation. That is, the minimum deviation between the actual speed of the spark-ignition engine and the target speed is the optimal value. The required ammonia injection quantity and the injection interval angle are both read from the vehicle controller.

[0011] Furthermore, the catalyst includes an SCR denitrification layer, an ASC oxidation catalyst layer, and an ASC oxygen supplementation catalyst layer connected in series. The SCR denitrification layer is connected to the ASC oxidation catalyst layer, and the ASC oxidation catalyst layer is connected to the ASC oxygen supplementation catalyst layer.

[0012] Furthermore, the tandem SCR denitrification layer is an ammonia selective catalytic reduction reaction, employing a V2O5-WO3 / TiO2 coating, operating at a temperature of 250-400℃, to remove NO. x It is converted into nitrogen gas and water vapor.

[0013] Furthermore, the ASC oxidation catalyst layer accelerates the ammonia oxidation reaction by increasing the ASC oxidation temperature through oxygen supplementation. It adopts a Pt-Pd / Al2O3 coating and operates at a temperature of 350-550℃, oxidizing NH3 that did not participate in the SCR reaction into N2 and H2O. The ASC oxygen supplementation catalyst layer is an ammonia collector and also integrates an air jet microporous array and Fe-ZSM-5 molecular sieve. It increases the local oxygen concentration through secondary air injection, ensuring that NH3 is fully oxidized in the low-temperature range of 200-300℃.

[0014] The present invention has the following positive effects: 1. This invention achieves precise estimation of the opening degree through the interaction between the electronic control valve, electronic intercooler, electronic turbocharger, ammonia injector, and throttle valve. This not only allows for precise control of the amount of ammonia entering the engine, resulting in more complete combustion and providing more energy to the engine, but also provides a highly reliable and low-emission solution for ammonia engines, suitable for heavy-duty scenarios such as commercial vehicles and ships.

[0015] 2. This invention expands the catalyst contact area by extending the length of the ASC carrier (adding a first-stage ASC carrier), thereby improving the ammonia adsorption capacity and oxidation efficiency. At the same time, to prevent more ammonia from escaping, the exhaust lambda needs to be controlled around 1.2, where lambda is read from the engine's matching front oxygen sensor. A secondary air injection device (air pump) is added before the aftertreatment SCR to increase the ASC oxidation temperature by supplementing oxygen, thereby accelerating the ammonia oxidation reaction. Simultaneously, closed-loop control of lambda is implemented to ensure sufficient oxygen content for the conversion and reduction of ammonia. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the system framework of the present invention.

[0017] The labels in the diagram are as follows: 1-Liquid ammonia cylinder, 2-Electrically controlled turbocharger, 3-Ammonia liquid evaporator, 4-Electronic control valve, 5-Engine injector, 6-Electrically controlled intercooler, 7-Throttle valve, 8-Ignition spark engine, 9-Catalyst, 901-Series SCR denitrification layer, 902-ASC oxidation catalyst layer, 903-ASC oxygen supplementation catalyst layer, 10-Drive motor assembly. Detailed Implementation

[0018] The exemplary embodiments of this disclosure are described below with reference to the accompanying drawings, including various details of the embodiments to aid understanding, and should be considered merely exemplary. Therefore, those skilled in the art will recognize that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of this disclosure. Similarly, for clarity and brevity, descriptions of well-known functions and structures are omitted in the following description.

[0019] Example 1: As Figure 1 As shown, an ignition and cold start control system for a pure ammonia engine includes a liquid ammonia cylinder 1, an electronically controlled intercooler 6, a throttle valve 7, an electric drive assembly 10, and an electronically controlled turbocharger 2. The output port of the liquid ammonia cylinder 1 is connected to the input port of an ammonia evaporator 3, and the output port of the ammonia evaporator 3 is connected to one end of an engine injector 5. The other end of the engine injector 5 is connected to one end of the engine intake manifold. Fresh air passes through the electronically controlled turbocharger 2 and is connected to the other end of the electronically controlled intercooler 6. The other end of the outlet of the electronically controlled intercooler 6 is connected to the throttle valve 7, and the output port of the throttle valve 7 is connected to one end of the engine intake manifold. The coolant of the electronically controlled turbocharger 2 is connected to the engine coolant and the electric drive assembly coolant through an electronically controlled valve 4. The other end of the spark-ignition engine 8 is connected to a catalytic converter 9.

[0020] In this embodiment, the internal emission control of the spark-ignition engine first involves entering lean-burn control, expanding the air-fuel ratio of the spark-ignition engine from the conventional 1.0-1.2 to >1.5, and reducing the combustion temperature by increasing the intake air volume, thereby reducing NO. x The generation of NOx also leaves an excess of oxygen in the cylinder, providing a basis for the aftertreatment system to process NOx. x It provides conditions for the redox reaction of NH3.

[0021] In this embodiment, the ignition angle of the spark-ignition engine is controlled at >34-36 degrees. When the knock intensity / knock limit is >0.7-0.9, the target ignition angle of the spark-ignition engine is -1.5-2.2 degrees. When the knock intensity / knock limit is <0.3-0.5, the ignition angle of the spark-ignition engine is set according to the target. The knock intensity and knock limit are read by the controller of the spark-ignition engine.

[0022] In this embodiment, the in-engine emission control of the spark-ignition engine employs secondary ammonia injection control, dividing the required ammonia injection amount into two equal injections. The interval angle between the two injections can be 200 degrees crankshaft angle, 220 degrees, or 240 degrees. The vehicle controller, through adaptive control, selects the optimal injection interval angle, and the optimal boundary is the engine speed fluctuation amount. That is, the minimum deviation between the actual speed of the spark-ignition engine and the target speed is the optimal value. The required ammonia injection amount and the injection interval angle are both read from the vehicle controller.

[0023] In this embodiment, the catalyst includes an SCR denitrification layer, an ASC oxidation catalyst layer, and an ASC oxygen supplementation catalyst layer connected in series. The SCR denitrification layer is connected to the ASC oxidation catalyst layer, and the ASC oxidation catalyst layer is connected to the ASC oxygen supplementation catalyst layer.

[0024] In this embodiment, the tandem SCR denitrification layer is an ammonia selective catalytic reduction reaction, using a V2O5-WO3 / TiO2 coating, operating at a temperature of 250-400℃, to remove NO. x It is converted into nitrogen gas and water vapor.

[0025] In this embodiment, the ASC oxidation catalyst layer accelerates the ammonia oxidation reaction by increasing the ASC oxidation temperature through oxygen supplementation. It adopts a Pt-Pd / Al2O3 coating and operates at a temperature of 350-550℃, oxidizing NH3 that has not participated in the SCR reaction into N2 and H2O. The ASC oxygen supplementation catalyst layer is an ammonia collector and also integrates an air jet microporous array and Fe-ZSM-5 molecular sieve. It increases the local oxygen concentration through secondary air injection, ensuring that NH3 is fully oxidized in the low-temperature range of 200-300℃.

[0026] In this embodiment, when the vehicle speed is greater than 50 km / h, the temperature of the liquid ammonia heating device reaches 60°C or higher, and the hybrid vehicle VECU (Vehicle Electronic Control Unit) issues an engine start request, the ammonia engine is ready to start.

[0027] The VECU requests engine start, and the alternator pulls the engine to the target idle speed (e.g., 1200 rpm), while the engine throttle is opened to its maximum (100% opening); at the same time, the engine intercooler shuts off, meaning there is no coolant flow to cool the air-fuel mixture.

[0028] After the vehicle completes the above steps, the opening of the electronic control valve is adjusted after 5 seconds to control the ammonia flow rate. The ammonia flow rate = fresh air flow rate / lambda (excess air coefficient), and closed-loop gas control is performed. Generally, lambda is controlled to be around 1.05 ± 0.05, where lambda is read from the engine's front oxygen sensor, and the fresh air flow rate can be read from the air flow sensor.

[0029] Temperature correction is applied to the magnetization time of the ignition coil to maximize its energy and enable rapid ignition of ammonia at low temperatures. The magnetization time is corrected by k according to the engine coolant temperature as shown in the table below. The final magnetization time = target magnetization time at room temperature * k. If the final magnetization time > the maximum magnetization time defined by the product, the final magnetization time = the maximum magnetization time defined by the product.

[0030] The engine ignition angle is controlled at >30 degrees. The ignition angle is defined as a positive value when it is greater than the top dead center. When knocking occurs, the current target ignition angle is reduced by 2 degrees. The knocking angle is the value monitored after the engine control detects knocking.

[0031] After successful ignition, the VECU will control the engine to operate stably.

[0032] Try to keep the engine operating at a rate of 80 Nm or higher.

[0033] 1. When the engine starts, electronic control valve A fully opens and begins to work, introducing engine coolant into the intercooler to increase the temperature of the air-fuel mixture entering the engine cylinders, while simultaneously closing the function of electronic control valve B; 2. When the engine intake manifold temperature > 60 degrees Celsius (calibrable) and the engine coolant outlet temperature > 80 degrees Celsius, electronic control valve A closes. Subsequently, the duty cycle of electronic control valve B controls the target intake manifold temperature required by the engine until the end of the current driving cycle (the vehicle stops working); the next time the vehicle is started, control will be performed according to 1-2 above.

[0034] When the vehicle's battery level is above 80%, the engine stops working. Subsequent starting needs are determined by the VECU's starting requirements, and the vehicle is driven by the battery-controlled drive motor.

[0035] Example 2: Based on the ignition and cold start control system of a pure ammonia engine in Example 1, the present invention will be further described and explained below.

[0036] like Figure 1As shown, an ignition and cold start control system for a pure ammonia engine includes a liquid ammonia cylinder 1, an electronically controlled intercooler 6, a throttle valve 7, an electric drive assembly 10, and an electronically controlled turbocharger 2. The output port of the liquid ammonia cylinder 1 is connected to the input port of an ammonia evaporator 3, and the output port of the ammonia evaporator 3 is connected to one end of an engine injector 5. The other end of the engine injector 5 is connected to one end of the engine intake manifold. Fresh air passes through the electronically controlled turbocharger 2 and is connected to the other end of the electronically controlled intercooler 6. The other end of the outlet of the electronically controlled intercooler 6 is connected to the throttle valve 7, and the output port of the throttle valve 7 is connected to one end of the engine intake manifold. The coolant of the electronically controlled turbocharger 2 is connected to the engine coolant and the electric drive assembly coolant through an electronically controlled valve 4. The other end of the spark-ignition engine 8 is connected to a catalytic converter 9.

[0037] In this embodiment, the catalyst 9 includes an SCR denitrification layer 901, an ASC oxidation catalyst layer 902, and an ASC oxygen supplementation catalyst layer 903 connected in series. The SCR denitrification layer 901 is connected to the ASC oxidation catalyst layer 902, and the ASC oxidation catalyst layer 902 is connected to the ASC oxygen supplementation catalyst layer 903.

[0038] In this embodiment, the series-connected SCR denitrification layer 901 is an ammonia selective catalytic reduction reaction, using a V2O5-WO3 / TiO2 coating, with an operating temperature of 250-400℃, converting NOx into nitrogen and water vapor.

[0039] In this embodiment, the ASC oxidation catalyst layer 902 accelerates the ammonia oxidation reaction by increasing the ASC oxidation temperature through oxygen supplementation. It adopts a Pt-Pd / Al2O3 coating and operates at a temperature of 350-550℃, oxidizing NH3 that has not participated in the SCR reaction into N2 and H2O. The ASC oxygen supplementation catalyst layer 903 is an ammonia collector and also integrates an air jet micropore array (pore size 50μm) and Fe-ZSM-5 molecular sieve. It increases the local oxygen concentration through secondary air injection, ensuring that NH3 is fully oxidized in the low-temperature range (200-300℃).

[0040] In this embodiment, the engine emission control first involves entering lean-burn control, expanding the engine air-fuel ratio (λ) from the conventional 1.0-1.2 to >1.5. This is achieved by increasing the intake air volume to reduce the combustion temperature and thus reduce NO. x The generation of NOx also leaves an excess of oxygen in the cylinder, providing a basis for the aftertreatment system to process NOx. x It provides conditions for the redox reaction of NH3.

[0041] The engine's operating ignition angle is controlled based on an ignition angle greater than 35 degrees. When the knock intensity / knock limit is greater than 0.8, the engine's target ignition angle is reduced by 2 degrees. When the knock intensity / knock limit is less than 0.4, the engine ignition angle is set according to the target. The knock intensity and knock limit can be read from the engine controller. Simultaneously, the in-engine emission control performs secondary ammonia injection control, dividing the required ammonia injection amount into two equal injections. The interval angle between the two injections can be 200 degrees crankshaft angle, 220 degrees, or 240 degrees. The vehicle controller can adaptively select the optimal injection interval angle. The optimal boundary is the engine speed fluctuation, that is, the minimum deviation between the actual engine speed and the target speed is the optimal value. The required ammonia injection amount and the injection interval angle can both be read from the vehicle controller.

[0042] Exhaust gas, after being burned in the engine cylinders, enters the pre-stage SCR as NO. x High-efficiency conversion core, front-end SCR as NO x The first line of defense in the treatment process involves the selective catalytic reduction of NO by ammonia (NH3). x It is converted into harmless nitrogen gas (N2) and water vapor (H2O).

[0043] To prevent further ammonia escape, the exhaust lambda needs to be controlled around 1.2, where lambda is read from the engine's front oxygen sensor. A secondary air injection device (air pump) is added before the aftertreatment SCR to increase the ASC oxidation temperature by supplementing oxygen, thereby accelerating the ammonia oxidation reaction. At the same time, closed-loop control of lambda is implemented to ensure sufficient oxygen content to complete the conversion and reduction of ammonia.

[0044] The downstream ASC not only acts as an ammonia collector but also integrates oxidation catalysis to oxidize unreacted ammonia (NH3) into nitrogen (N2), while simultaneously treating any trace amounts of NO that may remain in the upstream SCR. x .

[0045] By extending the length of the ASC support (adding a first-stage ASC support), the catalyst contact area is expanded, thereby improving the ammonia adsorption capacity and oxidation efficiency.

[0046] In summary, this invention not only precisely controls the amount of ammonia entering the engine, allowing for more complete combustion and providing more energy, but also provides a highly reliable, low-emission solution for ammonia engines, suitable for heavy-duty applications such as commercial vehicles and ships.

[0047] The specific embodiments described above do not constitute a limitation on the scope of protection of this disclosure. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this disclosure should be included within the scope of protection of this disclosure.

Claims

1. An ignition and cold start control system for a pure ammonia engine, comprising a liquid ammonia cylinder, an electronically controlled intercooler, a throttle valve, an electric drive assembly, and an electronically controlled turbocharger, characterized in that: The outlet of the liquid ammonia cylinder is connected to the input of the ammonia evaporator. The outlet of the ammonia evaporator is connected to one end of the engine injector. The other end of the engine injector is connected to one end of the engine intake manifold. Fresh air passes through the electronically controlled turbocharger and is connected to the other end of the electronically controlled intercooler. The other end of the outlet of the electronically controlled intercooler is connected to the throttle valve. The outlet of the throttle valve is connected to one end of the engine intake manifold. The coolant of the electronically controlled turbocharger is connected to the engine coolant and the electric drive assembly coolant through electronic control valves. The other end of the spark-ignition engine is connected to the catalytic converter.

2. The ignition and cold start control system for a pure ammonia engine according to claim 1, characterized in that: The internal emission control of the spark-ignition engine enters lean-burn control, and the air-fuel ratio of the spark-ignition engine is >1.

5.

3. The ignition and cold start control system for a pure ammonia engine according to claim 2, characterized in that: The ignition angle of the spark-ignition engine is controlled at >34-36 degrees. When the knock intensity / knock limit is >0.7-0.9, the target ignition angle of the spark-ignition engine is -1.5-2.2 degrees. When the knock intensity / knock limit is <0.3-0.5, the ignition angle of the spark-ignition engine is set according to the target. The knock intensity and knock limit are read by the controller of the spark-ignition engine.

4. The ignition and cold start control system for a pure ammonia engine according to claim 3, characterized in that: The in-engine emission control of the spark-ignition engine employs secondary ammonia injection control, dividing the required ammonia injection quantity into two equal injections. The interval angle between the two injections can be 200 degrees crankshaft angle, 220 degrees, or 240 degrees. The vehicle controller, through adaptive control, selects the optimal injection interval angle, and the optimal boundary is the engine speed fluctuation. That is, the minimum deviation between the actual speed of the spark-ignition engine and the target speed is the optimal value. The required ammonia injection quantity and the injection interval angle are both read from the vehicle controller.

5. The ignition and cold start control system for a pure ammonia engine according to claim 1, characterized in that: The catalyst includes an SCR denitrification layer, an ASC oxidation catalyst layer, and an ASC oxygen supplementation catalyst layer connected in series. The SCR denitrification layer is connected to the ASC oxidation catalyst layer, and the ASC oxidation catalyst layer is connected to the ASC oxygen supplementation catalyst layer.

6. The ignition and cold start control system for a pure ammonia engine according to claim 5, characterized in that: The series-connected SCR denitrification layer is an ammonia selective catalytic reduction reaction, using a V2O5-WO3 / TiO2 coating, operating at a temperature of 250-400℃, to remove NO. x It is converted into nitrogen gas and water vapor.

7. The ignition and cold start control system for a pure ammonia engine according to claim 5, characterized in that: The ASC oxidation catalyst layer accelerates the ammonia oxidation reaction by increasing the ASC oxidation temperature through oxygen supplementation. It adopts a Pt-Pd / Al2O3 coating and operates at a temperature of 350-550℃, oxidizing NH3 that has not participated in the SCR reaction into N2 and H2O. The ASC oxygen supplementation catalyst layer is an ammonia collector and also integrates an air jet microporous array and Fe-ZSM-5 molecular sieve. It increases the local oxygen concentration through secondary air injection, ensuring that NH3 is fully oxidized in the low-temperature range of 200-300℃.

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