Control method, device and system for reducing original emission peak nitrogen and oxygen of diesel engine and medium

Abstract

The invention discloses a control method, device and system for reducing original emission peak nitrogen and oxygen of a diesel engine and a medium. The control method comprises the following steps that the engine rotating speed collected by an engine rotating speed sensor and the fuel injection quantity collected by an accelerator pedal position sensor are obtained; according to the engine rotating speed and the fuel injection quantity, the post-injection quantity and the post-injection angle are determined by looking up a table MAP, and the corresponding relation between the engine rotating speed and the fuel injection quantity and the corresponding relation between the post-injection quantity and the post-injection angle are recorded in the table MAP; and a post-injection control instruction is generated, so that the oil injector injects the fuel oil of the post-injection oil quantity into the cylinder at the post-injection angle under the control of the control instruction. The total fuel injection quantity is injected into the cylinder in two times in a post-injection mode, peak nitrogen and oxygen emission can be greatly reduced under the condition that the smoke intensity and the fuel consumption are not greatly deteriorated, and the effect of reducing the peak nitrogen and oxygen through the method can not be affected by transient working condition changes.

Description

Technical Field

[0001] The present invention belongs to the technical field of peak nitrogen oxide control, and in particular relates to a control method, device, system and medium for reducing peak nitrogen oxide in diesel engine exhaust. Background Art

[0002] Diesel engines, due to their efficient heat release and higher fuel efficiency, have become the primary power source for commercial vehicles. To boost engine power, exhaust turbocharging technology is widely used. This increases the amount of air entering the engine by increasing air density, which in turn leads to an increase in nitrogen oxide (NOx) emissions from diesel engines. With the implementation of China VI emission regulations, total NOx emissions are being strictly controlled. The PEMS (Propellant Emission Measurement System) emission requirements specify that at least 95% of valid data points must contain concentrations below 500 ppm. These limits pose significant challenges to diesel engine NOx emissions, particularly peak NOx emissions.

[0003] The traditional peak NOx control method uses a main injection method, which has the following problems: (1) When controlling NOx emissions through the exhaust gas recirculation system (EGR), due to the hysteresis of the engine intake during rapid acceleration, the actual intake volume is less than the required intake volume. At this time, the EGR system is shut down, resulting in transient excessive NOx peaks. (2) The emission control of the high-efficiency SCR route does not have an EGR system. Peak NOx control relies on reducing the main injection advance angle and rail pressure, which leads to a sharp increase in particulate matter emissions and a serious decrease in fuel consumption. Summary of the Invention

[0004] In order to solve the problems of excessively high transient peak nitrogen oxides, sharp increases in particulate matter emissions, and decreased fuel consumption in existing peak nitrogen oxide control methods, the present invention provides a control method, device, system, and medium for reducing the peak nitrogen oxides in the original exhaust of a diesel engine.

[0005] The purpose of the present invention is achieved through the following technical solutions: A first aspect of the present invention discloses a control method for reducing peak nitrogen oxides in diesel engine exhaust, comprising the following steps: Obtain the engine speed collected by the engine speed sensor and the current fuel injection amount collected by the accelerator pedal position sensor; Determining the post-injection amount and the post-injection angle by looking up a table MAP according to the engine speed and the current injection amount, wherein the table MAP records the corresponding relationship between the engine speed, the current injection amount, the post-injection amount, and the post-injection angle; A post-injection control instruction is generated so that the injector, under the control of the control instruction, injects the post-injection amount of fuel into the cylinder at the post-injection angle, thereby injecting the total injection amount into the cylinder in two times.

[0006] A second aspect of the present invention discloses a control device for reducing the peak nitrogen and oxygen levels of the original exhaust of a diesel engine, comprising a memory and a controller that are communicatively connected in sequence, wherein the memory stores a computer program, and the controller is used to read the computer program and execute the control method for reducing the peak nitrogen and oxygen levels of the original exhaust of a diesel engine described in the first aspect.

[0007] The third aspect of the present invention discloses a computer-readable storage medium having instructions stored thereon. When the instructions are run on a computer, the control method for reducing the peak nitrogen oxides in the original exhaust of a diesel engine described in the first aspect is executed.

[0008] A fourth aspect of the present invention discloses a control system for reducing peak nitrogen oxides in diesel engine exhaust, comprising: An engine speed sensor for acquiring engine speed; Accelerator pedal position sensor for collecting current fuel injection amount; Fuel injectors; In the second aspect, a control device for reducing the peak nitrogen oxides in the original exhaust of a diesel engine is described, wherein the engine speed sensor, the accelerator pedal position sensor and the injector signal are connected to the control device for reducing the peak nitrogen oxides in the original exhaust of a diesel engine.

[0009] Compared with the prior art, the present invention has at least the following advantages and beneficial effects: The present invention adopts the post-injection method to inject the total injection amount into the cylinder twice, which can significantly reduce the peak nitrogen oxide emissions without much deterioration in smoke density and fuel consumption. The effect of this method on reducing peak nitrogen oxides is not affected by changes in transient operating conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0011] Figure 1 Flowchart of the method of the present invention. DETAILED DESCRIPTION

[0012] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0013] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are also within the scope of protection of the present invention.

[0014] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments of the present invention can be combined with each other.

[0015] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0016] In the description of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the inventive product is typically placed when in use, or are the orientations or positional relationships commonly understood by those skilled in the art. These terms are intended only to facilitate the description of the present invention and to simplify the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limiting the present invention. Furthermore, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0017] In the description of the present invention, it should also be noted that, unless otherwise expressly specified or limited, the terms "disposed," "installed," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to mechanical connections or electrical connections; they may refer to direct connections or indirect connections through an intermediate medium; and they may refer to internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0018] The first aspect of the present invention discloses a control method for reducing the peak nitrogen oxides of a diesel engine. Specifically, Figure 1 As shown, the method includes steps S1 to S3.

[0019] Step S1: Acquire the engine speed collected by the engine speed sensor and the current fuel injection amount collected by the accelerator pedal position sensor.

[0020] Step S2: Determine the post-injection amount and post-injection angle by looking up a table MAP according to the engine speed and the current injection amount. The table MAP records the corresponding relationship between the engine speed, the current injection amount, the post-injection amount, and the post-injection angle.

[0021] Specifically, the corresponding relationship between the engine speed, the current fuel injection amount, the post-injection amount, and the post-injection angle recorded in the table MAP is generated by bench testing.

[0022] The bench test process is as follows: Engine operating conditions: engine speed n0 torque trq0, total injection amount Q0, post-injection is turned on and the basic injection amount QOI0 and injection angle POI0 are given.

[0023] Adjust the rear spray angle and oil volume, and check whether the original nitrogen oxide emission results are controlled to the target value.

[0024] If the original NOx emission result does not reach the target value, the test is terminated and post-injection is not required to control NOx emissions at this operating point. Record the current operating point and the point at which post-injection is not required in the MAP table.

[0025] If the original NOx emission result is controlled to the target value, adjust the total injection amount to Q1, restore the torque at the current speed to trq0, continue to adjust the post-injection angle and oil volume and fine-tune the total injection amount. The final total injection amount is Q2, and the torque at the current speed is maintained at trq0, and the original NOx emission reaches the target value. Record the current operating point, the post-injection required at the current operating point, the post-injection angle and the post-injection amount in the MAP table. The total injection amount Q 1、 Q2 is greater than Q0.

[0026] Step S3: Generate a post-injection control instruction, so that the injector can inject the post-injection amount of fuel into the cylinder at the post-injection angle under the control of the control instruction, so as to inject the total injection amount into the cylinder twice.

[0027] This solution uses post-injection to inject a large amount of fuel, and the fuel that was originally injected into the cylinder in the main injection stage is divided into two injections into the cylinder using post-injection, thereby lowering the maximum temperature of combustion in the cylinder and achieving the purpose of reducing nitrogen oxide emissions.

[0028] In order to reflect the technical effect of this solution, the following are exemplified: A certain diesel engine is currently operating at 1400 rpm, with an engine torque output of 200 N∙m at a 39.7% throttle opening. The current fuel injection rate is 31.8 mg / hub. Using the existing main injection method, exhaust smoke density is 0.19 (FSN), NOx emissions are 1477.8 ppm, and specific fuel consumption is 206.7 g / kw∙h.

[0029] Using this method, we determined a post-injection angle of 3.9 degrees crankshaft angle and a post-injection fuel quantity of 16.2 mg / hub. The engine maintained a speed of 1400 rpm and an output torque of 200 N∙m. The throttle opening was 28.8%, and the current injection quantity was 23.4 mg / hub. Two post-injections were used to achieve this 16.2 mg / hub. Exhaust smoke density (FSN) was 0.23, NOx emissions were 985.4 ppm, and specific fuel consumption was 211.8 g / kWh.

[0030] It can be seen that by injecting the post-injection amount into the cylinder twice through post-injection, the peak nitrogen oxide emissions can be greatly reduced without much deterioration in smoke density and fuel consumption, and the effect of this method on reducing peak nitrogen oxides is not affected by changes in transient operating conditions.

[0031] A second aspect of the present invention discloses a control device for reducing peak NOx emissions from diesel engines, comprising a memory and a controller in communication with each other. The memory stores a computer program, and the controller is configured to read the computer program and execute the control method for reducing peak NOx emissions from diesel engines described in the first aspect. This device is the diesel engine's control unit (ECU).

[0032] The third aspect of the present invention discloses a computer-readable storage medium having instructions stored thereon. When the instructions are run on a computer, the control method for reducing the peak nitrogen oxides in the original exhaust of a diesel engine described in the first aspect is executed.

[0033] A fourth aspect of the present invention discloses a control system for reducing peak nitrogen oxides in diesel engine exhaust, comprising: An engine speed sensor for acquiring engine speed; Accelerator pedal position sensor for collecting current fuel injection amount; Fuel injectors; In the second aspect, a control device for reducing the peak nitrogen oxides in the original exhaust of a diesel engine is described, wherein the engine speed sensor, the accelerator pedal position sensor and the injector signal are connected to the control device for reducing the peak nitrogen oxides in the original exhaust of a diesel engine.

[0034] The operating principles of the devices, media and structures disclosed in the second to fourth aspects of the present invention are the same as those in the first aspect and will not be described in detail here.

[0035] Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A control method for reducing peak nitrogen oxides in diesel engine exhaust, characterized in that: The following steps are involved: Obtain the engine speed collected by the engine speed sensor and the current fuel injection amount collected by the accelerator pedal position sensor; Determining whether to use post-injection, the post-injection amount, and the post-injection angle by looking up a table MAP according to the engine speed and the current injection amount, wherein the table MAP records the corresponding relationship between the engine speed, the current injection amount, the post-injection amount, and the post-injection angle; In response to the need for post-injection, a post-injection control instruction is generated so that the injector, under the control of the control instruction, injects the post-injection amount of fuel into the cylinder at the post-injection angle, thereby injecting the total injection amount into the cylinder in two times.

2. A control device for reducing peak nitrogen oxides in diesel engine exhaust, comprising a memory and a controller in sequential communication connection, wherein the memory stores a computer program, characterized in that: The controller is used to read the computer program and execute the control method for reducing the peak nitrogen oxides in the original exhaust of a diesel engine according to any one of claim 1.

3. A computer-readable storage medium having instructions stored thereon, characterized in that: When the instructions are executed on a computer, a control method for reducing peak nitrogen oxides in diesel engine exhaust as claimed in any one of claims 1 is executed.

4. A control system for reducing peak nitrogen oxides in diesel engine exhaust, characterized in that: include: An engine speed sensor for acquiring engine speed; Accelerator pedal position sensor for collecting current fuel injection amount; Fuel injectors; A control device for reducing the peak nitrogen oxides of a diesel engine as described in claim 2, wherein the engine speed sensor, the accelerator pedal position sensor and the injector signal are connected to the control device for reducing the peak nitrogen oxides of a diesel engine.

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