Engine small load emission control method and engine
By employing homogeneous impulse ignition and exhaust pipe electric heating in the diesel engine idling state, the problem of increased nitrogen oxide emissions in the idling state was solved, achieving low-energy and low-cost nitrogen oxide treatment.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- TIANJIN UNIV
- Filing Date
- 2023-11-22
- Publication Date
- 2026-07-03
Smart Images
Figure CN117432542B_ABST
Abstract
Description
Technical Field
[0001] This disclosure relates to the field of diesel internal combustion engine technology, and more specifically, to an engine low-load emission control method and an engine. Background Technology
[0002] The idling state of a diesel engine refers to the state in which the diesel engine operates at its lowest stable speed under no-load conditions. Under idling conditions, the emission of nitrogen oxides produced by the diesel engine will increase, so corresponding measures need to be taken to deal with the nitrogen oxides produced by the engine under idling conditions.
[0003] In existing technologies, nitrogen oxides generated in diesel engines are treated using selective catalytic reduction (SCR). This method requires first injecting urea into the diesel engine's exhaust aftertreatment system, and then allowing the urea to react with the nitrogen oxides in the SCR system to produce water and nitrogen.
[0004] However, selective catalytic reduction requires a high operating temperature, above 200°C, while the exhaust temperature of a diesel engine is low at idle. Therefore, the exhaust gas from the diesel engine needs to be heated, which is energy-intensive and costly. Summary of the Invention
[0005] To address at least one technical problem described above and in other aspects of the prior art, this disclosure provides a method for controlling engine emissions under low load and an engine. By responding to a reference injection timing, the engine is placed in a homogeneous charge impulse ignition state to reduce nitrogen oxides in the exhaust gas and generate a target gas. The engine's exhaust pipe is heated, and the target gas discharged from the engine is heated to a target temperature for catalytic conversion of the target gas. This target temperature is lower than the operating temperature at which urea reacts with nitrogen oxides, thereby reducing energy consumption and the cost of treating nitrogen oxides.
[0006] One embodiment of this disclosure provides an engine low-load emission control method, comprising: acquiring a first processing parameter suitable for removing nitrogen oxides generated by an engine in an idling state, and a first emission amount of a target gas generated by the engine; controlling the engine to inject fuel at a reference injection time while the engine is idling, so that the engine is in a homogeneous charge impulse compression ignition (HCCI) state to reduce nitrogen oxides in the exhaust gas and form the target gas; electrically heating the exhaust pipe of the engine to bring the target gas to a target temperature suitable for catalysis, so that at least a portion of the target gas is catalyzed; acquiring a second processing parameter associated with the amount of electricity consumed in heating the exhaust pipe, and a second emission amount of the uncatalyzed target gas; delaying the reference injection time and / or reducing the amount of electricity consumed until the second processing parameter is less than or equal to the first processing parameter, and the second emission amount is less than or equal to the first emission amount, outputting the reference injection time as the target injection time, and also outputting a target electrical parameter for electrically heating the exhaust pipe of the engine; and maintaining the engine injecting fuel at the target injection time and heating the exhaust pipe with the target electrical parameter.
[0007] According to embodiments of this disclosure, the above-mentioned acquisition of a first processing parameter suitable for removing nitrogen oxides generated by an engine in an idling state, and a first emission amount of a target gas generated from removing the nitrogen oxides, includes: in an engine idling state, acquiring a urea consumption amount suitable for removing the nitrogen oxides generated by the engine, and a first emission amount of a target gas composed of unburned hydrocarbons and carbon monoxide in the exhaust gas; and calculating the cost of the urea consumption amount as the first processing parameter.
[0008] According to embodiments of this disclosure, when the engine is idling, the engine is controlled to inject fuel at a reference injection time to put the engine into a homogeneous charge impulse compression ignition state, thereby reducing nitrogen oxides in the exhaust gas and forming the target gas. This includes: setting the temperature of the engine's coolant and lubricating oil to between 25°C and 30°C to put the engine in an idling state; and controlling the engine to inject fuel at the reference injection time when the piston of the engine is 30° to 40° before top dead center of the crankshaft.
[0009] According to an embodiment of this disclosure, the target gas is brought to a suitable target temperature for catalysis by electrically heating the exhaust pipe of the engine, so that at least a portion of the target gas is catalyzed. This includes: using the catalytic temperature at which the target gas is catalyzed as the target temperature; and detecting the temperature of the target gas in the exhaust pipe and adjusting the power of the electric heating until the target gas in the exhaust pipe is maintained at the target temperature.
[0010] According to embodiments of this disclosure, the target temperature is limited to achieving a catalytic conversion rate of 97% or higher for the target gas at the target temperature.
[0011] According to an embodiment of this disclosure, obtaining a second processing parameter associated with the electricity consumed in heating the exhaust pipe and a second emission amount of the uncatalyzed target gas includes: obtaining the electricity consumed in heating the exhaust pipe and calculating the cost of the electricity consumed as the second processing parameter.
[0012] According to embodiments of this disclosure, the reference injection timing is delayed and / or the power consumption is reduced until the second processing parameter is less than or equal to the first processing parameter, and the second emission is less than or equal to the first emission. Then, the reference injection timing is output as the target injection timing, and target power parameters for electrically heating the engine's exhaust pipe are also output. Delaying the reference injection timing includes postponing the injection timing by 2 degrees of crankshaft rotation. Reducing the power consumption includes reducing the voltage by 5 volts to decrease power consumption.
[0013] Another aspect of the present invention provides an engine controlled based on the above-described low-load emission control method, comprising: an engine body adapted for homogeneous charge impulse compression ignition; an engine control unit adapted for controlling and adjusting the injection timing of the engine body; an exhaust aftertreatment system comprising: an exhaust pipe adapted for discharging exhaust gas generated by the engine body; a heating device disposed on the exhaust pipe adapted for heating the target gas discharged from the engine body to a target temperature; a urea injection device disposed downstream of the heating device adapted for injecting urea into the exhaust gas; a urea injection control unit adapted for controlling the urea injection device to inject urea into the exhaust gas and for outputting the urea consumption amount; a target gas catalytic converter disposed downstream of the heating device adapted for catalytic conversion of at least a portion of the target gas discharged from the engine body; a nitrogen oxide catalytic converter disposed downstream of the urea injection device adapted for catalytic conversion of nitrogen oxides in the exhaust gas containing urea; and an exhaust gas sensor disposed at the discharge end of the exhaust pipe adapted for detecting the nitrogen oxide emission amount and the emission amount of the target gas after catalytic conversion by the target gas catalytic converter.
[0014] According to embodiments of this disclosure, the exhaust gas aftertreatment system further includes a temperature sensor disposed on the target gas catalytic device, which is suitable for detecting the temperature of the target gas passing through the target gas catalytic device.
[0015] According to an embodiment of this disclosure, the heating device further includes a temperature control unit adapted to control the heating power of the heating device so as to maintain the target gas at the target temperature.
[0016] According to the low-load emission control method and engine provided in this disclosure, by idling the engine, first processing parameters suitable for removing nitrogen oxides produced by the engine and a first emission amount of the target gas produced by the engine are obtained as reference benchmarks. The idling engine performs homogeneous charge impulse compression ignition based on a target injection timing to burn nitrogen oxides and heats the target gas produced based on the homogeneous charge impulse compression ignition to a target temperature to reduce the emission of the target gas, thereby reducing engine exhaust emissions. By delaying the target injection timing and / or reducing the power consumption for heating the target gas, a second processing parameter associated with the power consumption is made less than or equal to the first processing parameter, and the second emission amount of the target gas produced by homogeneous charge impulse compression ignition is made less than or equal to the first emission amount of the target gas, to obtain the target injection timing and target power consumption parameters. This allows the engine in the idling state to achieve the same or lower exhaust emissions while consuming less energy and at a lower cost. Attached Figure Description
[0017] Figure 1 This is a flowchart of an engine low-load emission control method according to an illustrative embodiment of the present disclosure;
[0018] Figure 2 This is a schematic structural diagram of an engine according to an illustrative embodiment of the present disclosure;
[0019] In the accompanying drawings, the meanings of the reference numerals are as follows:
[0020] 10-Engine body;
[0021] 11-Fuel injection control unit;
[0022] 12-Throttle body;
[0023] 13-Intercooler;
[0024] 14-Turbocharger;
[0025] 20 - Exhaust pipe;
[0026] 21-Heating device;
[0027] 22-Target gas catalytic converter;
[0028] 23-Urea injection device;
[0029] 24-Nitrogen oxide catalytic unit;
[0030] 25 - Exhaust gas sensor;
[0031] 26 - Temperature sensor;
[0032] 27-Temperature control unit;
[0033] 28 - Particle trap. Detailed Implementation
[0034] To make the objectives, technical solutions, and advantages of this disclosure clearer, the following detailed description is provided in conjunction with specific embodiments and the accompanying drawings.
[0035] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.
[0036] All terms used herein, including technical and scientific terms, have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.
[0037] When using expressions such as "at least one of A, B, and C," the meaning should generally be interpreted according to the understanding of someone skilled in the art. For example, "a system having at least one of A, B, and C" should include, but is not limited to, systems having A alone, having B alone, having C alone, having A and B, having A and C, having B and C, and / or having A, B, and C. Similarly, when using expressions such as "at least one of A, B, or C," the meaning should generally be interpreted according to the understanding of someone skilled in the art. For example, "a system having at least one of A, B, or C" should include, but is not limited to, systems having A alone, having B alone, having C alone, having A and B, having A and C, having B and C, and / or having A, B, and C.
[0038] In existing technologies, the catalytic conversion of nitrogen oxides at engine idling requires injecting urea into the engine's exhaust aftertreatment system and heating the exhaust gas to 200°C, which results in high processing costs and high energy consumption.
[0039] Therefore, given the aforementioned shortcomings of existing technologies, how to achieve low-cost and low-energy treatment of nitrogen oxide emissions from engines during idling has become an urgent technical problem to be solved.
[0040] In view of this, the present disclosure provides a method for controlling engine emissions under low load and an engine.
[0041] Figure 2 This is a schematic structural diagram of an engine according to an illustrative embodiment of the present disclosure.
[0042] According to the engine provided in this disclosure, such as Figure 2 As shown, the system includes an engine block 10, a fuel injection control unit, and an exhaust aftertreatment system. The engine block 10 is used for homogeneous charge impulse compression ignition. The fuel injection control unit 11 is used to control and adjust the fuel injection timing of the engine block 10. The exhaust aftertreatment system includes: an exhaust pipe 20 for discharging exhaust gas generated by the engine block 10; a heating device 21, disposed on the exhaust pipe 20, for heating the target gas discharged from the engine block 10 to a target temperature; a urea injection device 23, disposed downstream of the heating device 21, for injecting urea into the exhaust gas; a urea injection control unit (not shown), for controlling the injection of urea by the urea injection device 23 into the exhaust gas and for controlling the amount of urea consumed; a target gas catalytic converter 22, disposed downstream of the heating device 21, for catalytically converting at least a portion of the target gas discharged from the engine block 10; and a nitrogen oxide catalytic converter 24, disposed downstream of the urea injection device 23, for catalytically converting nitrogen oxides in the urea-injected exhaust gas. The exhaust gas sensor 25 is located at the exhaust end of the exhaust pipe 20 and is suitable for detecting the amount of nitrogen oxides emitted and the amount of target gas emitted after catalytic conversion by the target gas catalytic device 22.
[0043] According to embodiments of this disclosure, such as Figure 2 As shown, the exhaust aftertreatment system also includes a particulate filter 28 for reducing particulate emissions generated by the engine body 10.
[0044] According to embodiments of this disclosure, such as Figure 2 As shown, the nitrogen oxide catalytic device 24 also includes an ammonia trap (not shown) for recovering and storing the ammonia remaining after the reaction of nitrogen oxides and urea.
[0045] In one illustrative embodiment, such as Figure 2 As shown, the exhaust gas aftertreatment system also includes a temperature sensor 26, which is installed on the target gas catalytic device 22 and is suitable for detecting the temperature of the target gas passing through the target gas catalytic device 22.
[0046] In one illustrative embodiment, such as Figure 2 As shown, the heating device 21 also includes a temperature control unit 27, which is used to control the heating power of the heating device 21 to keep the target gas at the target temperature.
[0047] According to the above setup, urea can be injected into the nitrogen oxides emitted by the engine at idle to obtain the first treatment parameters and the first emission amount of the target gas as references. Then, the injection timing is adjusted by the fuel injection control unit, and the engine homogeneous impulse compression ignition is controlled to consume nitrogen oxides and emit the target gas. The target gas is also heated to catalytically convert it, thereby achieving effective treatment of nitrogen oxides. Based on the first treatment parameters and the first emission amount as references, the fuel injection timing and the electrical parameters used for heating are adjusted, thereby achieving nitrogen oxide treatment with lower energy consumption and lower cost with zero urea consumption.
[0048] Figure 1 This is a flowchart of an engine low-load emission control method according to an illustrative embodiment of the present disclosure.
[0049] According to the engine low-load emission control method provided in this disclosure, such as Figure 1 As shown, the engine control method includes, but is not limited to, steps S110-S160.
[0050] Step S110: Obtain first processing parameters suitable for removing nitrogen oxides generated by an engine in an idling state, and first emission amount of target gas generated by the engine.
[0051] Step S120: When the engine is idling, control the engine to inject fuel at the reference injection time so that the engine is in the working state of homogeneous charge impulse compression ignition, so as to reduce nitrogen oxides in the exhaust gas and form the target gas.
[0052] Step S230: By electrically heating the exhaust pipe of the engine, the target gas is brought to a target temperature suitable for catalysis, so that at least a portion of the target gas is catalyzed.
[0053] Step S140: Obtain a second processing parameter associated with the amount of electricity consumed in heating the exhaust pipe, and a second emission amount of the uncatalyzed target gas.
[0054] Step S150: Delay the reference injection time and / or reduce the power consumption until the second processing parameter is less than or equal to the first processing parameter and the second emission is less than or equal to the first emission. Then, output the reference injection time as the target injection time and also output the target power consumption parameter for electric heating of the engine's exhaust pipe.
[0055] Step S160: Maintain the engine injecting fuel at the target injection time and heat the exhaust pipe with the target electrical parameters.
[0056] According to the above implementation method, homogeneous impulse compression ignition (HEM) of the engine at idle speed can consume nitrogen oxides. Because HEM ignition occurs at a relatively low temperature, the engine also produces a significant amount of the target gas. The target gas is then heated to a target temperature to initiate a catalytic reaction, thereby reducing the emissions of nitrogen oxides and the target gas. Considering that heating the target gas also incurs energy consumption and heating costs, it is necessary to obtain the first treatment parameters and the first emission amount of the target gas as a reference by injecting urea into the nitrogen oxides. By comparing the second processing parameter with the first processing parameter and the second emission amount with the first emission amount, and adjusting the reference injection timing to reduce the emission amount of the target gas and / or reduce the electricity consumed in heating the target gas, the second processing parameter associated with the target gas can be effectively reduced until the second processing parameter is less than or equal to the first processing parameter and the second emission amount is less than or equal to the first emission amount. This yields engine control parameters (i.e., target injection timing and target electrical parameters) that are superior to those obtained in the prior art by injecting urea and using selective catalytic reduction. Based on the aforementioned target injection timing and target electrical parameters, an engine operating at idle can treat nitrogen oxides at a lower cost and with less energy consumption.
[0057] In one illustrative embodiment, step S110 includes: with the engine idling, obtaining the urea consumption for removing nitrogen oxides produced by the engine, and the first emission amount of the target gas consisting of unburned hydrocarbons and carbon monoxide in the exhaust gas; and calculating the cost of the urea consumption as a first processing parameter.
[0058] In one illustrative embodiment, step S120 includes: controlling the engine to inject fuel at a reference injection time while the engine is idling, so that the engine is in a homogeneous charge impulse compression ignition state to reduce nitrogen oxides in the exhaust gas and form the target gas, including: setting the temperature of the engine coolant and the temperature of the lubricating oil between 25°C and 30°C to keep the engine in an idling state; and controlling the engine to inject fuel at a reference injection time when the piston is 30° to 40° before top dead center of the crankshaft.
[0059] In this embodiment, the engine is controlled to inject fuel at a reference injection time when the piston is 30° to 40° before top dead center. This can effectively burn nitrogen oxides, so that the nitrogen oxide emissions are less than or equal to the nitrogen oxide emissions treated by injecting urea.
[0060] In one illustrative embodiment, step S130 includes: using the catalytic temperature at which the target gas is catalyzed as the target temperature; and detecting the temperature of the target gas in the exhaust pipe and adjusting the power of the electric heating until the target gas in the exhaust pipe is maintained at the target temperature.
[0061] In one illustrative embodiment, the target temperature is defined as such that the catalytic conversion rate of the target gas at the target temperature is above 97%.
[0062] According to an embodiment of this disclosure, the target temperature is 150°C.
[0063] In one illustrative embodiment, step S140 includes: obtaining the amount of electricity consumed in heating the exhaust pipe, and calculating the cost of the consumed electricity as the second processing parameter.
[0064] In one illustrative embodiment, step S150 includes delaying the reference injection timing by 2 degrees of crankshaft rotation. Reducing power consumption includes reducing the voltage by 5 volts to decrease power consumption.
[0065] Based on the above settings, by making small adjustments to the injection timing and power consumption, it is helpful to more accurately determine the target injection timing and target power consumption parameters.
[0066] In one illustrative embodiment, the target injection time is recorded and stored by the fuel injection control unit, and the target electrical parameters are recorded and stored by the temperature control unit.
[0067] According to the above settings, when the engine is idling, the nitrogen oxides produced by the engine can be treated by directly calling the target injection time and target electrical parameters, so as to reduce energy consumption and save costs.
[0068] Based on the above technical solution, the engine low-load emission control method disclosed herein can at least achieve the beneficial technical effect of lower cost and less energy consumption for treating nitrogen oxides while having the same or less nitrogen oxide emissions.
[0069] It should also be noted that the directional terms mentioned in the embodiments, such as "up," "down," "front," "back," "left," and "right," are only for reference to the directions in the accompanying drawings and are not intended to limit the scope of protection of this disclosure. Throughout the drawings, the same elements are represented by the same or similar reference numerals. Conventional structures or constructions will be omitted where they may cause confusion in understanding this disclosure.
[0070] The embodiments of this disclosure have been described above. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of this disclosure. Although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination. The scope of this disclosure is defined by the appended claims and their equivalents. Various substitutions and modifications can be made by those skilled in the art without departing from the scope of this disclosure, and all such substitutions and modifications should fall within the scope of this disclosure.
Claims
1. A method for controlling engine emissions under low load, characterized in that, include: Obtain first processing parameters suitable for removing nitrogen oxides produced by an engine in an idling state, and a first emission amount of the target gas produced by the engine; When the engine is idling, the engine is controlled to inject fuel at a reference injection time so that the engine is in a homogeneous charge impulse compression ignition state, thereby reducing nitrogen oxides in the exhaust gas and forming the target gas. By electrically heating the exhaust pipe of the engine, the target gas is brought to a target temperature suitable for catalysis, so that at least a portion of the target gas is catalyzed; Acquire a second processing parameter associated with the amount of electricity consumed in heating the exhaust pipe, and a second emission amount of the uncatalyzed target gas; The reference injection time is delayed and / or the power consumption is reduced until the second processing parameter is less than or equal to the first processing parameter and the second emission is less than or equal to the first emission. Then, the reference injection time is output as the target injection time, and the target power consumption parameter for electric heating of the exhaust pipe of the engine is also output. as well as The engine is maintained to inject fuel at the target injection time, and the exhaust pipe is heated with the target electrical parameters.
2. The engine low-load emission control method according to claim 1, characterized in that, The process of obtaining first treatment parameters suitable for removing nitrogen oxides generated by an engine at idle speed, and a first emission amount of the target gas generated from removing the nitrogen oxides, includes: With the engine idling, obtain the urea consumption suitable for removing nitrogen oxides produced by the engine, and the first emission amount of the target gas consisting of unburned hydrocarbons and carbon monoxide in the exhaust gas; and The cost of the urea consumption is calculated as the first processing parameter.
3. The engine low-load emission control method according to claim 2, characterized in that, When the engine is idling, the engine is controlled to inject fuel at a reference injection time to ensure that the engine is in a homogeneous charge impulse compression ignition state, thereby reducing nitrogen oxides in the exhaust gas and forming the target gas, including: The engine's coolant and lubricating oil temperatures are set between 25°C and 30°C to keep the engine at idle; and The engine is controlled to inject fuel at a reference injection time when the piston of the engine is between 30° and 40° before top dead center of the crankshaft.
4. The engine low-load emission control method according to claim 1, characterized in that, By electrically heating the exhaust pipe of the engine to bring the target gas to a target temperature suitable for catalysis, so that at least a portion of the target gas is catalyzed, the following methods are employed: The target temperature is defined as the catalytic temperature at which the target gas is catalyzed; and The temperature of the target gas in the exhaust pipe is detected, and the power of the electric heating is adjusted until the target gas in the exhaust pipe is maintained at the target temperature.
5. The engine low-load emission control method according to claim 4, characterized in that, The target temperature is defined as such that the catalytic conversion rate of the target gas at the target temperature is above 97%.
6. The engine low-load emission control method according to claim 4, characterized in that, Acquiring a second processing parameter associated with the electricity consumed in heating the exhaust pipe, and a second emission rate of the uncatalyzed target gas, including: The amount of electricity consumed in heating the exhaust pipe is obtained, and the cost of the consumed electricity is calculated as the second processing parameter.
7. The engine low-load emission control method according to claim 6, characterized in that, The reference injection timing is delayed and / or the power consumption is reduced until the second processing parameter is less than or equal to the first processing parameter, and the second emission amount is less than or equal to the first emission amount. Then, the reference injection timing is output as the target injection timing, and target power parameters for the electric heating of the engine's exhaust pipe are also output, including: The delay of the reference injection timing includes: delaying the injection timing by 2 degrees of crankshaft rotation angle; Reducing power consumption includes lowering the voltage by 5 volts to reduce power consumption.
8. An engine controlled based on the low-load emission control method of any one of claims 1-7, characterized in that, include: The engine body is suitable for homogeneous impulse compression ignition. Fuel injection control unit: Applicable to controlling and adjusting the fuel injection timing of the engine body; The exhaust aftertreatment system includes: An exhaust pipe is used to discharge exhaust gases produced by the engine body. A heating device, disposed on the exhaust pipe, is suitable for heating the target gas discharged from the engine body to the target temperature; A urea injection device is located downstream of the heating device and is suitable for injecting urea into the exhaust gas; A urea injection control unit is adapted to control the urea injection device to inject urea into the exhaust gas, and to output the amount of urea consumed. A target gas catalytic device, located downstream of the heating device, is suitable for catalytically converting at least a portion of the target gas discharged from the engine body; A nitrogen oxide catalytic converter, located downstream of the urea injection device, is suitable for the catalytic conversion of nitrogen oxides in the exhaust gas from which urea is injected; and An exhaust gas sensor is installed at the exhaust end of the exhaust pipe and is suitable for detecting the emission of nitrogen oxides and the emission of target gas after catalytic conversion by the target gas catalytic device.
9. The engine according to claim 8, characterized in that, The exhaust gas aftertreatment system also includes a temperature sensor, which is installed on the target gas catalytic device and is suitable for detecting the temperature of the target gas passing through the target gas catalytic device.
10. The engine according to claim 9, characterized in that, The heating device also includes a temperature control unit, which is adapted to control the heating power of the heating device to maintain the target gas at the target temperature.