Control system and control strategy for reducing urea injection crystallization-induced blockage

Abstract

A control system and control strategy for reducing urea injection crystallization-induced blockage. In the control system, a liquid outlet of a urea tank is communicated with a liquid inlet of a urea pump by means of a liquid inlet pipe, and the urea pump draws a urea solution from the urea tank by means of the liquid inlet pipe; a nozzle is communicated with a liquid outlet of the urea pump by means of an injection pipe, and the urea pump can convey the urea solution to the nozzle for injection by means of the injection pipe; a liquid return pipe is provided between a liquid return opening of the urea pump and a liquid return opening of the urea tank; the urea pump has a back-suction function, and by means of the back-suction function of the urea pump, residual urea solution in the nozzle can be suctioned back into the urea pump through the injection pipe and then the residual urea solution is conveyed back to the urea tank through the liquid return pipe; an ECU controller is in electrical data connection with the urea pump, the urea tank and the nozzle, and the ECU controller can control specific actions of the urea pump suctioning liquid from the urea tank, conveying liquid to the nozzle, returning liquid to the urea tank and performing graded back-suction from the nozzle.

Description

Control system and control strategy for reducing urea injection crystallization blockage Technical Field

[0001] The present invention relates to the field of engine design and manufacturing, and in particular to a control system and a control strategy for reducing urea injection crystallization blockage. Background Art

[0002] With the upgrading of emission regulations, diesel engines generally adopt high-efficiency SCR (Selective Catalytic Reduction) technology to reduce exhaust NOx emissions. However, with the application of urea injection systems, nozzle crystallization failures have become more frequent. The rationality of the urea injection strategy has a significant impact on nozzle crystallization. A reasonable urea injection strategy can significantly reduce the risk of urea crystallization.

[0003] The control strategy of the existing technology mostly adopts a thorough back suction control after the injection system completes the injection command, allowing the urea solution in the injection pipe to flow back to the urea tank. However, the existing technology cannot effectively solve the existing frequent failure problem caused by nozzle crystallization due to unreasonable urea injection strategy.

[0004] The information disclosed in this background technology section is only intended to enhance understanding of the overall background of the invention and should not be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art. Summary of the Invention

[0005] The object of the present invention is to provide a control system for reducing urea injection crystallization blockage, which can effectively prevent the urea solution from evaporating at high temperature and crystallizing to block the nozzle through back suction graded control of urea injection.

[0006] Another object of the present invention is to provide a control strategy for reducing urea injection crystallization blockage, which can perform graded control of urea injection backdraft according to the specific conditions of the vehicle, thereby preventing the high-temperature evaporation of urea solution from crystallizing and clogging the nozzle.

[0007] To achieve the above-mentioned object, the present invention provides a control system for reducing urea injection crystallization blockage, comprising a urea pump, a urea tank, a nozzle, a liquid return pipe, and an ECU controller; the liquid outlet of the urea tank is connected to the liquid inlet of the urea pump via the liquid inlet pipe, and the urea pump extracts urea solution from the urea tank via the liquid inlet pipe; the nozzle is connected to the liquid outlet of the urea pump via the injection pipe, and the urea pump can deliver urea solution to the nozzle through the injection pipe for injection; the liquid return pipe is arranged between the liquid return port of the urea pump and the liquid return port of the urea tank; the urea pump has a back suction function, and the residual urea solution in the nozzle can be sucked back into the urea pump through the liquid injection pipe by the back suction function of the urea pump, and then delivered back to the urea tank through the liquid return pipe; the ECU controller is electrically data connected to the urea pump, the urea tank, and the nozzle, and can control the specific actions of the urea pump in sucking liquid from the urea tank, delivering liquid to the nozzle, returning liquid to the urea tank, and back suctioning liquid from the nozzle in stages.

[0008] In a preferred embodiment, the control system for reducing urea injection crystallization blockage also includes an engine CAN bus, which is electrically connected to the ECU controller. The ECU controller receives engine information through the engine CAN bus, and at the same time, based on the injection requirements put forward by the engine and by monitoring the status of the urea tank, issues injection instructions to the urea pump and nozzle to execute the injection action.

[0009] To achieve the above-mentioned other purpose, the present invention also provides a control strategy for reducing urea injection crystallization blockage, which is completed by the control system as described above. The control strategy includes: the ECU controller obtains the requirements put forward by the engine through the engine CAN bus, and the ECU controller sends an injection execution instruction to the injection pump and nozzle as needed; and when the injection pump and nozzle have no injection instruction received or have completed the injection instruction, they will enter the judgment and waiting instruction state of the backflow operation.

[0010] In a preferred embodiment, the control strategy also includes a control logic step for determining whether to enter graded backdraft: differentiation is made according to the operating characteristics or usage scenarios of the vehicle. For some vehicles that are used intermittently, the graded backdraft strategy is not entered, and a complete backdraft strategy is completed within a backdraft time of 60 seconds before entering a waiting instruction state for stopping work.

[0011] In a preferred embodiment, the control strategy also includes: when the control logic of entering the graded backdraft is determined according to the operating characteristics or usage scenarios of the vehicle, the temperature judgment step is entered; when the ambient temperature is lower than -5°C, a complete backdraft strategy is executed with a backdraft time of 60s to prevent the residual urea from freezing at low temperatures, affecting the heating and thawing effect, and even damaging the injection device; after the complete backdraft strategy is completed, the vehicle enters a waiting instruction state for stopping work.

[0012] In a preferred embodiment, the control strategy also includes: when the control logic of entering the graded backdraft is determined according to the operating characteristics or usage scenarios of the vehicle, it enters the temperature judgment step. When the ambient temperature is higher than -5°C and lower than 30°C, it is further determined whether the ambient temperature is lower than 150°C. When the temperature is lower than 150°C, a complete backdraft strategy is executed with a backdraft time of 60s to prevent the urea solution from evaporating and clogging the nozzle under high temperature conditions.

[0013] In a preferred embodiment, the temperature judgment step of the control strategy further includes: when the exhaust temperature is greater than 150°C, executing an incomplete backdraft strategy with a backdraft time of 20s, and entering a waiting instruction state for stopping work after completing the above backdraft strategy.

[0014] In a preferred embodiment, the control strategy also includes: entering the temperature judgment step after judging the control logic of entering the graded back suction according to the operating characteristics or usage scenarios of the vehicle; when the ambient temperature is higher than 30°C, further judging whether the ambient temperature is lower than 150°C; when the temperature is lower than 150°C, executing the complete back suction strategy to prevent the urea solution from evaporating and clogging the nozzle under high temperature conditions.

[0015] In a preferred embodiment, the control strategy also includes: entering the temperature judgment step after entering the control logic of graded backdraft according to the operating characteristics or usage scenarios of the vehicle. When the exhaust temperature is greater than 150°C, an incomplete backdraft strategy is executed with a backdraft time of 10s. After completing the above backdraft strategy, the system enters the waiting instruction state for stopping work.

[0016] Compared with the prior art, the control system and control strategy for reducing urea injection crystallization blockage of the present invention have the following beneficial effects: this solution is applicable to all engines using urea injection devices, implements a graded backdraft control strategy based on the use of different vehicles, different ambient temperatures, and different exhaust temperature states, has good operability, and proposes a new method for reducing the risk of urea crystallization; at higher temperatures, a portion of urea is retained in the urea pipe, that is, incomplete backdraft, which is achieved by reducing the backdraft time, preventing the urea solution from evaporating (high temperature) and crystallizing, thereby preventing the nozzle from clogging; the backdraft control strategy is based on the different application characteristics, ambient temperature, and exhaust temperature of the vehicle, and achieves optimization through a graded backdraft strategy. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] FIG1 is a schematic diagram of the equipment layout of a control system according to an embodiment of the present invention;

[0018] FIG2 is a control logic diagram of a control strategy according to an embodiment of the present invention. DETAILED DESCRIPTION

[0019] The specific embodiments of the present invention are described in detail below with reference to the accompanying drawings, but it should be understood that the protection scope of the present invention is not limited by the specific embodiments.

[0020] Unless expressly stated otherwise, throughout the specification and claims, the term "comprise" or variations such as "include" or "comprising", etc., will be understood to include the stated elements or components but not to exclude other elements or other components.

[0021] As shown in FIG1 , a control system for reducing urea injection crystallization blockage according to a preferred embodiment of the present invention includes a urea pump, a urea tank, a nozzle, a liquid return pipe, and an ECU controller. The liquid outlet of the urea tank is connected to the liquid inlet of the urea pump via the liquid inlet pipe, and the urea pump extracts urea solution from the urea tank via the liquid inlet pipe. The nozzle is connected to the liquid outlet of the urea pump via the injection pipe, and the urea pump can deliver urea solution to the nozzle through the injection pipe for injection. The liquid return pipe is arranged between the liquid return port of the urea pump and the liquid return port of the urea tank. The urea pump has a back suction function, and the residual urea solution in the nozzle can be sucked back into the urea pump through the liquid injection pipe by the back suction function of the urea pump, and then delivered back to the urea tank through the liquid return pipe. The ECU controller is electrically data connected to the urea pump, the urea tank, and the nozzle. The ECU controller can control the specific actions of the urea pump in sucking liquid from the urea tank, delivering liquid to the nozzle, returning liquid to the urea tank, and back suctioning liquid from the nozzle in stages.

[0022] In a preferred embodiment, the control system for reducing urea injection crystallization blockage also includes an engine CAN bus, which is electrically connected to the ECU controller. The ECU controller receives engine information through the engine CAN bus, and at the same time, based on the injection requirements put forward by the engine and by monitoring the status of the urea tank, issues injection instructions to the urea pump and nozzle to execute the injection action.

[0023] As shown in Figure 2, a control strategy for reducing urea injection crystallization blockage according to a preferred embodiment of the present invention is implemented by the control system as described above. The control strategy includes: the ECU controller obtains the requirements of the engine through the engine CAN bus, and the ECU controller issues an injection execution instruction to the injection pump and nozzle as needed; and when the injection pump and nozzle receive no injection instruction or have completed the injection instruction, they will enter the judgment and waiting instruction state of the backflow operation.

[0024] In some embodiments, the control strategy also includes a control logic step for determining whether to enter graded backdraft: differentiation is made according to the operating characteristics or usage scenarios of the vehicle. For some vehicles that are used intermittently, the graded backdraft strategy is not entered, and a complete backdraft strategy is completed within a backdraft time of 60 seconds before entering a waiting instruction state for stopping work.

[0025] In some embodiments, the control strategy also includes: when the control logic of entering the graded backdraft is determined according to the operating characteristics or usage scenarios of the vehicle, it enters the temperature judgment step; when the ambient temperature is lower than -5°C, a complete backdraft strategy is executed with a backdraft time of 60s to prevent the residual urea from freezing at low temperatures, affecting the heating and thawing effect, and even damaging the injection device; after completing the complete backdraft strategy, it enters the waiting instruction state for stopping work.

[0026] In some embodiments, the control strategy also includes: when the control logic for entering the graded backdraft is determined based on the vehicle's operating characteristics or usage scenarios, entering the temperature judgment step, when the ambient temperature is higher than -5°C and lower than 30°C, further determining whether the ambient temperature is lower than 150°C. When the temperature is lower than 150°C, executing the full backdraft strategy with a backdraft time of 60s to prevent the urea solution from evaporating and clogging the nozzle under high temperature conditions.

[0027] In some embodiments, the temperature determination step of the control strategy further includes: when the exhaust temperature is greater than 150°C, executing an incomplete backdraft strategy with a backdraft time of 20s, and entering a waiting instruction state for stopping work after completing the above backdraft strategy.

[0028] In some embodiments, the control strategy further includes: entering a temperature judgment step after entering a graded backdraft control logic according to the vehicle's operating characteristics or usage scenarios; when the ambient temperature is higher than 30°C, further judging whether the ambient temperature is lower than 150°C; when the temperature is lower than 150°C, executing a complete backdraft strategy to prevent the urea solution from evaporating and clogging the nozzle under high temperature conditions.

[0029] In some embodiments, the control strategy also includes: entering the temperature judgment step after entering the control logic of graded backdraft according to the operating characteristics or usage scenarios of the vehicle. When the exhaust temperature is greater than 150°C, an incomplete backdraft strategy is executed with a backdraft time of 10s. After completing the above backdraft strategy, the system enters the waiting instruction state for stopping work.

[0030] In summary, the control system and control strategy for reducing urea injection crystallization blockage of the present invention have the following advantages: this solution is applicable to all engines using urea injection devices, and implements a graded backdraft control strategy according to the uses of different vehicles, different ambient temperatures, and different exhaust temperature states, with good operability, and proposes a new method for reducing the risk of urea crystallization; at higher temperatures, a portion of urea is retained in the urea pipe, that is, incomplete backdraft, which is achieved by reducing the backdraft time, preventing the urea solution from evaporating (high temperature) and crystallizing, thereby clogging the nozzle; the backdraft control strategy is based on the different application characteristics, ambient temperature, and exhaust temperature of the vehicle, and achieves the optimization purpose through a graded backdraft strategy.

[0031] The foregoing descriptions of specific exemplary embodiments of the present invention are for purposes of illustration and description. These descriptions are not intended to limit the invention to the precise forms disclosed, and it is apparent that many variations and modifications are possible in light of the foregoing teachings. The exemplary embodiments have been selected and described for the purpose of explaining the specific principles of the invention and their practical application, thereby enabling those skilled in the art to realize and utilize a variety of exemplary embodiments of the invention and various options and modifications. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A control system for reducing urea injection crystal blockage, characterized in that: include: Urea pump; A urea tank, whose liquid outlet is connected to the liquid inlet of the urea pump through a liquid inlet pipe, and the urea pump extracts urea solution from the urea tank through the liquid inlet pipe; a nozzle, which is connected to the liquid outlet of the urea pump through an injection pipe, and the urea pump can deliver urea solution to the nozzle through the injection pipe for injection; A liquid return pipe, which is arranged between the liquid return port of the urea pump and the liquid return port of the urea tank; The urea pump has a back suction function, and the residual urea solution in the nozzle can be sucked back into the urea pump through the liquid spray pipe by the back suction function of the urea pump, and then the residual urea solution is transported back to the urea tank through the liquid return pipe; as well as An ECU controller is electrically connected to the urea pump, the urea tank and the nozzle, and the ECU controller can control the specific actions of the urea pump to suck liquid from the urea tank, deliver liquid to the nozzle, return liquid to the urea tank and suck liquid from the nozzle in stages.

2. The control system for reducing urea injection crystal blockage according to claim 1, characterized in that: It also includes an engine CAN bus, which is electrically connected to the ECU controller. The ECU controller receives engine information through the engine CAN bus, and at the same time, according to the injection requirements put forward by the engine and by monitoring the status of the urea tank, it issues injection instructions to the urea pump and the nozzle to perform the injection action.

3. A control strategy for reducing urea injection crystallization blockage, which is implemented by the control strategy according to claims 1 to 2, characterized in that: The control strategy includes: The ECU controller obtains the requirements of the engine through the engine CAN bus, and the ECU controller sends an injection execution instruction to the injection pump and the nozzle as required; and When the injection pump and the nozzle receive no injection instruction or have completed the injection instruction, they will enter the judgment and waiting instruction state of the back suction operation.

4. The control strategy for reducing urea injection crystal blockage as claimed in claim 3, characterized in that: The control strategy also includes a control logic step for determining whether to enter graded back suction: differentiating according to the vehicle's operating characteristics or usage scenarios, for some vehicles that are used intermittently, the graded back suction strategy is not entered, and a complete back suction strategy is completed within a back suction time of 60 seconds before entering a waiting instruction state for stopping work.

5. The control strategy for reducing urea injection crystal blockage as claimed in claim 3, characterized in that: The control strategy also includes: when the control logic of entering the graded back suction is judged according to the vehicle's operating characteristics or usage scenarios, it enters the temperature judgment step. When the ambient temperature is lower than -5°C, a complete back suction strategy is executed with a back suction time of 60s to prevent the residual urea from freezing at low temperature, affecting the heating and thawing effect, and even damaging the injection device. After completing the complete back suction strategy, it enters the waiting instruction state for stopping work.

6. The control strategy for reducing urea injection crystal blockage as claimed in claim 3, characterized in that: The control strategy also includes: when the control logic of entering the graded back suction is judged according to the vehicle's operating characteristics or usage scenarios, it enters the temperature judgment step. When the ambient temperature is higher than -5°C and lower than 30°C, it is further judged whether the ambient temperature is lower than 150°C. When the temperature is lower than 150°C, a complete back suction strategy is executed with a back suction time of 60s to prevent the urea solution from evaporating and clogging the nozzle under high temperature conditions.

7. The control strategy for reducing urea injection crystal blockage according to claim 6, characterized in that: The temperature judgment step of the control strategy also includes: when the exhaust temperature is greater than 150° C., an incomplete backdraft strategy is executed, and the backdraft time is 20 seconds. After completing the above backdraft strategy, the system enters a waiting instruction state for stopping work.

8. The control strategy for reducing urea injection crystal blockage as claimed in claim 3, characterized in that: The control strategy also includes: entering a temperature judgment step after entering a control logic of graded back suction according to the operating characteristics or usage scenarios of the vehicle; when the ambient temperature is higher than 30°C, further judging whether the ambient temperature is lower than 150°C; when the temperature is lower than 150°C, executing a complete back suction strategy to prevent the urea solution from evaporating and clogging the nozzle under high temperature conditions.

9. The control strategy for reducing urea injection crystal blockage according to claim 8, characterized in that: The control strategy also includes: entering the temperature judgment step after entering the control logic of graded backdraft according to the vehicle's operating characteristics or usage scenarios; when the exhaust temperature is greater than 150°C, executing an incomplete backdraft strategy with a backdraft time of 10s; and entering a waiting instruction state for stopping work after completing the above backdraft strategies.

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