Diesel engine aftertreatment electric heater EHD control method and system

Abstract

The invention discloses a diesel engine aftertreatment electric heater EHD control method and system. The system comprises an EHD electric heater, a circuit protector, a circuit relay, a CPU controller, an engine main control unit, a catalysis unit, an engine and a power module. An engine exhausts engine tail gas, the engine tail gas is guided into an EHD electric heater located at the front end of the aftertreatment system through an exhaust branch pipe to be heated, the heated tail gas flows into a catalytic unit to be subjected to catalytic conversion, and the tail gas is exhausted into the atmosphere; the circuit relay is connected to the CPU controller, and an opening and closing circuit of the circuit relay is passively controlled by the CPU controller; the engine main control unit is connected to an engine, and the CPU controller establishes information bidirectional interaction with the engine main control unit through CAN communication and obtains operation condition information of the engine. Autonomous closed-loop control is carried out on the EHD electric heater, so that the EHD electric heater is integrated into a whole vehicle control system, and more reasonable and controllable emission is achieved.

Description

Technical Field

[0002] The present invention relates to the technical field of engine exhaust gas treatment, and specifically to a control method and system for an electric heater EHD for post-treatment of diesel engines. Background Art

[0003] As a crystallization of human industry, diesel internal combustion engines have become an indispensable part of production operations. In the post-treatment of off-engine emissions reduction on the catalytic carrier combination, the mainstream route DOC+SDPF+SCR+ASC combined with EHD electric heating has become the first choice.

[0004] The main difficulty in achieving near-zero emissions is the cold start emissions test, which poses new challenges to the thermal management of the engine itself and the technical means when the temperature of the off-engine emissions reduction exhaust gas is low. The conversion of pollutants in the exhaust gas by the post-treatment catalytic converter shows different trends according to the exhaust gas temperature. Among them, SCR is more sensitive to the selective catalytic reduction of NOx, and the SCR conversion efficiency at low exhaust gas temperatures is significantly lower than that at high temperatures. For engines with poor cold start emissions or thermal management, the off-engine emissions reduction effect will be greatly reduced. Summary of the Invention

[0005] The present invention provides a control method and system for an electric heater EHD for post-treatment of diesel engines that can effectively prompt the catalyst to quickly reach the optimal activity range to achieve reasonable and controllable emissions, and can solve at least one of the above technical problems.

[0006] To solve the above technical problems, the present invention adopts the following technical solutions: A control method for an electric heater EHD for post-treatment of diesel engines, comprising the following steps: S1. The CPU controller interacts with the engine main control unit via the CAN bus, obtains the engine operating condition information, judges whether the engine is running, judges whether the exhaust gas flow output after the engine is running meets the minimum requirement, and judges whether the power supply voltage meets the minimum requirement; S2. If all the above conditions are met, enter the hysteresis temperature judgment mechanism; if any condition is not met, the CPU controller controls the circuit relay to disconnect; S3. Based on the function heating release strategy, design the expected heating temperature and the limit value, and design the hysteresis temperature range; S4. The EHD inlet / outlet temperature sensor collects the EHD electric heater inlet / outlet temperature, judges whether the engine is in the cold start and low temperature operation stage, and whether the EHD electric heater needs to be enabled; S5. Compare the temperature sampling value with the hysteresis temperature expected value / limit value based on the hysteresis temperature judgment mechanism. If the temperature sampling value is lower than the hysteresis expected value, the CPU controller controls the circuit relay to close, and the EHD electric heater starts heating. If the temperature sampling value is higher than the hysteresis limit value, the CPU controller controls the circuit relay to open, and the EHD electric heater stops heating.

[0007] Further, in the above S5, since the EHD electric heater starts heating operation, the timer starts timing. When the heating time reaches the set time threshold T, the CPU controller controls the circuit relay to open.

[0008] Further, in the above S5, the EHD electric heater releases heat energy during heating operation, and the heat is transferred by the exhaust gas to the catalytic unit of the aftertreatment system to improve the activation performance rate.

[0009] Further, in the above S1, the engine main control unit samples the air flow entering the cylinder for combustion through an air flow meter installed in the intake pipeline, adds it to the fuel consumption, and calculates the exhaust gas flow. This exhaust gas flow is sent to the CPU controller via the CAN bus to determine whether it meets the minimum working requirement of the EHD electric heater.

[0010] A diesel engine aftertreatment electric heater EHD control system applicable to the above diesel engine aftertreatment electric heater EHD control method includes an EHD electric heater, a circuit protector, a circuit relay, a CPU controller, an engine main control unit, a catalytic unit, an engine, and a power supply module; The engine discharges engine exhaust gas, which is guided by the exhaust manifold to the EHD electric heater located at the front end of the aftertreatment system for heating. The exhaust gas after heat treatment flows into the catalytic unit for catalytic conversion and then is discharged into the atmosphere; The power supply module is used to provide power support. Its negative pole is connected to the negative power port of the EHD electric heater, and its positive pole is connected to the circuit protector. After being connected and controlled by the circuit relay, it is input to the positive power port of the EHD electric heater; The circuit relay is connected to the CPU controller, and the opening and closing circuit of the circuit relay is passively controlled by the CPU controller; The engine main control unit is connected to the engine. The CPU controller establishes two-way information interaction with the engine main control unit via CAN communication and obtains the operating condition information of the engine.

[0011] Further, it also includes an EHD inlet temperature sensor and an EHD outlet temperature sensor. The EHD inlet temperature sensor is installed before the EHD electric heater and is used to collect the inlet temperature of the EHD electric heater. The EHD outlet temperature sensor is installed between the EHD electric heater and the catalytic unit and is used to collect the outlet temperature of the EHD electric heater. The sampling signals of the EHD inlet temperature sensor and the EHD outlet temperature sensor are both input into the CUP controller.

[0012] Further, the EHD electric heater uses ceramics or metal as a carrier and is used to convert electrical energy into heat energy and transfer heat through the exhaust gas flow.

[0013] Further, the engine serves as an engine output power source and is used to guide the exhaust gas temperature and flow to the EHD electric heater through the exhaust manifold.

[0014] Further, the circuit protector is connected to the positive pole of the EHD electric heater and is close to the input end of the power supply module.

[0015] Further, the circuit relay is connected to the positive pole of the EHD electric heater and is located behind the circuit protector.

[0016] The beneficial effects of the present invention are reflected in: An auxiliary temperature raising device, namely an EHD electric heater control system and an optimized control method, is added to the post-treatment system of the present invention to raise the exhaust gas temperature, enabling each catalyst in the post-treatment system to reach the optimal activity range faster. Through autonomous closed-loop control of the EHD electric heater, it is integrated into the vehicle control system, achieving more reasonable and controllable emissions for engines with poor cold start emissions or thermal management. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The schematic embodiments and descriptions thereof are used to explain the present application and do not constitute an improper limitation to the present application.

[0018] Figure 1 It is a schematic diagram of the overall flow of the control method of the embodiment of the present invention.

[0019] Figure 2 It is a schematic diagram of the logic of the control method of the embodiment of the present invention.

[0020] Figure 3 It is a diagram showing the experimental process data of the embodiment of the present invention.

[0021] Figure 4 It is a schematic diagram of the overall structure of the control system of the embodiment of the present invention.

[0022] Figure 5 It is a structural block diagram of a computer device according to an embodiment of the present invention. Specific embodiments

[0023] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0024] It should be noted that the meaning of "and / or" appearing throughout the text includes three parallel solutions. Taking "A and / or B" as an example, it includes solution A, solution B, or a solution that satisfies both A and B at the same time. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the fact that those of ordinary skill in the art can implement them. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the protection scope required by the present invention.

[0025] See Figure 1 - Figure 2 , an embodiment of the present invention provides a control method for a diesel engine aftertreatment electric heater EHD, including the following steps: S1. The CPU controller interacts with the engine main control unit via the CAN bus, obtains the engine operating condition information, judges whether the engine is running, judges whether the exhaust gas flow output after the engine is running meets the minimum requirement, and judges whether the power supply voltage meets the minimum requirement; S2. If all the above conditions are met, enter the hysteresis temperature judgment mechanism. If any condition is not met, the CPU controller controls the circuit relay to disconnect; S3. Based on the function heating release strategy, design the expected value and limit value of the heating temperature, and design the hysteresis temperature range; S4. The EHD inlet / outlet temperature sensor collects the EHD electric heater inlet / outlet temperature, judges whether the engine is in the cold engine low temperature operation stage, and whether the EHD electric heater needs to be enabled; S5. Based on the hysteresis temperature judgment mechanism, compare the temperature sampling value with the hysteresis temperature expected value / limit value. If the temperature sampling value is lower than the hysteresis expected value, the CPU controller controls the circuit relay to close, and the EHD electric heater starts to heat. If the temperature sampling value is higher than the hysteresis limit value, the CPU controller controls the circuit relay to disconnect, and the EHD electric heater stops heating.

[0026] In this embodiment, in S5, since the EHD electric heater starts heating operation, the timer starts timing. When the heating time reaches the set time threshold T, the CPU controller controls the circuit relay to disconnect, preventing the EHD electric heater from being heated for a long time, causing power feed, and avoiding affecting the normal operation of other vehicle components. Generally, the time threshold T is set to 10 min.

[0027] In this embodiment, in S5, the EHD electric heater releases heat energy during heating operation, and the heat is transferred by the exhaust gas to the catalytic unit of the aftertreatment system to improve the activation performance rate.

[0028] In this embodiment, in S1, the engine main control unit samples the air flow entering the cylinder for combustion via an air flow meter installed in the intake pipeline, adds it to the fuel consumption, and calculates the exhaust gas flow. This exhaust gas flow is sent to the CPU controller via the CAN bus to determine whether it meets the minimum working requirement of the EHD electric heater, preventing the EHD electric heater from working under a small air flow and causing component dry burning damage.

[0029] Generally, the minimum requirement for the exhaust gas flow output from the engine is 80 kg / h. The CPU controller collects whether the power supply voltage meets the minimum requirement through its own pressure sampling chip. For the 24V system, it is not less than 22V, and for the 12V system, it is not less than 10V.

[0030] The EHD heating energy release strategy performs closed-loop control according to the set expected heating temperature and the hysteresis temperature value. Temperature sampling feedback is carried out by the EHD outlet temperature sensor installed at the rear end of the EHD electric heater outlet. Its principle can be summarized as follows: When the engine starts and the exhaust gas volume is greater than the minimum requirement, if the sampled temperature is lower than the lower limit value of the hysteresis temperature (expected value, generally set to 240 °C), the CPU controller controls the circuit relay to close, and the EHD electric heater starts working. Since the heating operation starts, the timer starts timing. If the sampled temperature is higher than the upper limit value of the hysteresis temperature (limit value, generally set to 250 °C) within 10 min, the CPU controller controls the circuit relay to disconnect, and the EHD electric heater stops working, and the timer is reset to 0. If the sampled temperature is not higher than the upper limit value of the hysteresis temperature within 10 min, the CPU controller controls the circuit relay to disconnect, and the EHD electric heater stops working, and this process repeats.

[0031] To further prove this control method, the present invention has been verified through the bench WHTC cycle, effectively improving the temperature of each catalytic unit within the cycle, enabling it to reach the optimal activation range faster, especially significantly improving the NOx catalytic reduction efficiency. As Figure 3 shown, the test process data is presented in Tables 1 - 3 below: Table 1 Results of turning on and off the EHD in the first 600 seconds of WHTC Table 2 Results of the entire WHTC with EHD enabled and disabled Table 3 Influence of enabling and disabling EHD on the tailpipe emission results during the WHTC cycle Through the WHTC bench cycle test, it can be seen that after the EHD product is equipped with the control method provided by the present invention, the improvement of the final tailpipe emission results is obvious, laying a solid foundation for meeting the new stage emission regulations.

[0032] See Figure 4 , the embodiment of the present invention also provides a diesel engine aftertreatment electric heater EHD control system, which is applicable to the diesel engine aftertreatment electric heater EHD control method, and includes an EHD electric heater, a circuit protector, a circuit relay, a CPU controller, an engine main control unit, a catalytic unit, an engine and a power supply module; The exhaust gas of the engine is discharged through the exhaust manifold and guided to the EHD electric heater located at the front end of the aftertreatment system for heating. The heated exhaust gas flows into the catalytic unit for catalytic conversion and then is discharged into the atmosphere; The power supply module is used to provide power support. The negative pole is connected to the negative power port of the EHD electric heater, and the positive pole is connected to the circuit protector. After being controlled by the circuit relay, it is input to the positive power port of the EHD electric heater; The circuit relay is connected to the CPU controller, and the opening and closing circuit of the circuit relay is passively controlled by the CPU controller; The engine main control unit is connected to the engine. The CPU controller establishes two-way information interaction with the engine main control unit via CAN communication and obtains the operating condition information of the engine.

[0033] In this embodiment, it further includes an EHD inlet temperature sensor and an EHD outlet temperature sensor. The EHD inlet temperature sensor is installed before the EHD electric heater and is used to collect the inlet temperature of the EHD electric heater. The EHD outlet temperature sensor is installed between the EHD electric heater and the catalytic unit and is used to collect the outlet temperature of the EHD electric heater. The sampling signals of the EHD inlet temperature sensor and the EHD outlet temperature sensor are both input to the CUP controller.

[0034] In this embodiment, the EHD electric heater uses ceramics or metal as a carrier and is the main object to be controlled by this control method. As an electric heating device, it is used to convert electrical energy into heat energy and transfer the heat through the exhaust gas flow.

[0035] In this embodiment, the engine serves as an engine output power source and is used to guide the exhaust gas temperature and flow to the EHD electric heater through the exhaust manifold.

[0036] In this embodiment, the circuit protector is connected to the positive electrode of the EHD electric heater and is close to the input end of the power supply module. The essence of the circuit protector is to protect the circuit. When the current is too large, it can actively disconnect the circuit to protect the system.

[0037] In this embodiment, the circuit relay is connected to the positive electrode of the EHD electric heater and is located after the circuit protector. The circuit relay controls its own open / closed circuit signal through the CUP controller to control the activation and deactivation of the EHD electric heater.

[0038] In this embodiment, the power supply module is a power supply device, generally set to battery energy storage, and no special limitation is made here.

[0039] In this embodiment, the CPU controller is used to store the function strategy code involved in the control method of the present invention, receive and control the execution commands of each component, and realize the autonomous control of the EHD electric heater.

[0040] The embodiment of the present invention also provides a computer-readable storage medium storing a computer program. When the computer program is executed by a processor, the processor is caused to execute the steps of the EHD control method for diesel engine post-treatment as described above.

[0041] See Figure 5 , the embodiment of the present invention also provides a computer device including a memory and a processor. The memory stores a computer program. When the computer program is executed by the processor, the processor is caused to execute the steps of the EHD control method for diesel engine post-treatment as described above.

[0042] The embodiment of the present invention also provides a computer program product containing instructions. When it runs on a computer, the computer is caused to execute the steps of the EHD control method for diesel engine post-treatment as described above.

[0043] It can be understood that the system, device, and storage medium provided by the embodiment of the present invention correspond to the method provided by the embodiment of the present invention. For the explanations, examples, and beneficial effects of related content, reference can be made to the corresponding parts in the EHD control method for diesel engine post-treatment as described above.

[0044] It should be noted that those of ordinary skill in the art can understand that all or part of the steps implemented in the embodiments of the present invention can be implemented in whole or in part through software, hardware, firmware, or any combination thereof. When implemented using hardware, it can be implemented in whole or in part in the form of purchasing standard parts or modified parts. When implemented using software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of the present application are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center by wire (such as coaxial cable, optical fiber, digital subscriber line (DSL)) or wirelessly (such as infrared, wireless, microwave, etc.). The computer-readable storage medium can be any available medium that the computer can access or a data storage device such as a server or data center that includes one or more integrated available media. The available medium can be a magnetic medium (such as a floppy disk, hard disk, magnetic tape), an optical medium (such as a DVD), or a semiconductor medium (such as a solid state disk (SSD)).

[0045] It should be understood that the examples and embodiments described herein are only for illustration and are not intended to limit the present invention. Those skilled in the art can make various modifications or changes based on it. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A diesel engine aftertreatment electric heater EHD control method, characterized in that: The following steps are involved: S1, the CPU controller interacts with the engine main control unit via the CAN bus to obtain engine operating information, determine whether the engine is running, determine whether the exhaust gas flow output after the engine is running meets the minimum requirement, and determine whether the power supply voltage meets the minimum requirement; S2. If all the above conditions are met, the hysteresis temperature judgment mechanism is entered. If any condition is not met, the CPU controller controls the circuit relay to disconnect; S3. Based on the function heating release strategy, design the expected value and limit value of the heating temperature, and design the hysteresis temperature range; S4, EHD inlet / outlet temperature sensor collects the inlet / outlet temperature of the EHD electric heater to determine whether the engine is in the cold engine low temperature operation stage and whether the EHD electric heater needs to be enabled; S5. Compare the temperature sampling value with the hysteresis temperature expected value / limit value based on the hysteresis temperature judgment mechanism. If the temperature sampling value is lower than the hysteresis expected value, the CPU controller controls the circuit relay to close and the EHD electric heater starts heating. If the temperature sampling value is higher than the hysteresis limit value, the CPU controller controls the circuit relay to disconnect and the EHD electric heater stops heating.

2. The diesel engine aftertreatment electric heater EHD control method according to claim 1, characterized in that: In S5, the timer starts timing from the start of the EHD electric heater heating, and when the heating time reaches the set time threshold T, the CPU controller controls the circuit relay to disconnect.

3. The diesel engine aftertreatment electric heater EHD control method according to claim 1, characterized in that: In S5, the EHD electric heater releases heat energy during heating, and the heat is transferred from the exhaust gas to the catalytic unit of the post-treatment system to improve the activation performance rate.

4. The diesel engine aftertreatment electric heater EHD control method according to claim 1, characterized in that: In S1, the engine main control unit samples the air flow entering the cylinder for combustion via an air flow meter installed in the intake pipe, and calculates the exhaust gas flow by adding it to the fuel consumption. The exhaust gas flow is sent to the CPU controller via the CAN bus to determine whether the minimum working requirements of the EHD electric heater are met.

5. A diesel engine aftertreatment electric heater EHD control system, applicable to the diesel engine aftertreatment electric heater EHD control method according to any one of claims 1 to 4, characterized in that: Including EHD electric heater, circuit protector, circuit relay, CPU controller, engine main control unit, catalytic unit, engine and power module; The exhaust gas from the engine is directed to the EHD electric heater located at the front end of the post-treatment system through the exhaust branch pipe for heating, and the exhaust gas after heating flows into the catalytic unit for catalytic conversion and then discharged into the atmosphere; The power module is used to provide power support, the negative pole is connected to the negative power port of the EHD electric heater, the positive pole is connected to the circuit protector, and after being connected and controlled by the circuit relay, it is input to the positive power port of the EHD electric heater; The circuit relay is connected to the CPU controller, and the opening and closing circuits of the circuit relay are passively controlled by the CPU controller; The engine main control unit is connected to the engine, and the CPU controller establishes two-way information interaction with the engine main control unit via CAN communication, and obtains the operating condition information of the engine.

6. The diesel engine aftertreatment electric heater EHD control system as claimed in claim 5, characterized in that: It also includes an EHD inlet temperature sensor and an EHD outlet temperature sensor. The EHD inlet temperature sensor is installed before the EHD electric heater and is used to collect the inlet temperature of the EHD electric heater. The EHD outlet temperature sensor is installed between the EHD electric heater and the catalytic unit and is used to collect the outlet temperature of the EHD electric heater. The sampling signals of the EHD inlet temperature sensor and the EHD outlet temperature sensor are both input into the CUP controller.

7. The diesel engine aftertreatment electric heater EHD control system as claimed in claim 5, characterized in that: The EHD electric heater uses ceramic or metal as a carrier, and is used to convert electrical energy into thermal energy and transfer heat through the exhaust gas flow.

8. The diesel engine aftertreatment electric heater EHD control system as claimed in claim 5, characterized in that: The engine serves as an engine output power source, and is used to guide the exhaust gas temperature and flow rate to the EHD electric heater through the exhaust branch pipe.

9. The diesel engine aftertreatment electric heater EHD control system as claimed in claim 5, characterized in that: The circuit protector is connected to the positive electrode of the EHD electric heater and is close to the input terminal of the power module.

10. The diesel engine aftertreatment electric heater EHD control system as claimed in claim 5, characterized in that: The circuit relay is connected to the positive electrode of the EHD electric heater and is located after the circuit protector.

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