SCR system temperature control system and temperature control pressure building method

Abstract

The application discloses a kind of SCR system temperature control system and temperature control pressure building method, control system includes: controller, urea tank, urea pump, pressure pipe, return pipe, suction pipe, water cut electromagnetic valve;Method is: collecting temperature data in engine ECM judges SCR system state;According to the state of SCR system, cold start or hot start SCR system is selected;Urea pump, urea tank is heated respectively, and in the process of urea pump, urea tank heating, the temperature data of urea solution is collected in real time respectively according to the temperature data of urea solution, and according to the temperature data of urea solution, it is selected to thaw urea pump, urea tank, pressure pipe, return pipe, suction pipe, and based on the mode of cold start or hot start SCR system, it is selected to determine that SCR system thawing is completed, and after SCR system thawing is completed, SCR system pressure building is carried out, the system and method of the application distinguish cold start and hot start of SCR system, improve efficiency, so that it is suitable for a variety of temperature environment working conditions.

Description

Technical Field

[0001] This invention belongs to the technical field of diesel engine exhaust gas treatment systems, and specifically relates to a temperature control system and a temperature control pressure build-up method for an SCR system. Background Technology

[0002] With the upgrading of emissions standards for non-road machinery and road vehicles in China, nitrogen oxide emissions are a significant indicator. One effective method to reduce nitrogen oxide levels in exhaust gases is the use of a selective catalytic reduction (SCR) system. This system utilizes ammonia produced from the decomposition of urea (a nitrogen compound that readily decomposes into ammonia) to react with nitrogen oxides under the action of a catalyst, reducing them to N2 and water. However, the urea solution in the SCR system can freeze or solidify at temperatures below -11°C, preventing the system from supplying urea and affecting its normal operation. Therefore, it is necessary to heat and thaw components that come into contact with the urea solution, such as the urea tank, urea pump, and urea pipelines, to ensure the normal flow and supply of urea to the SCR system. Current SCR system heating methods utilize the temperature of the engine's internal coolant to defrost, heat, and maintain the urea tank and urea pump; or use heating wires to heat the urea lines; the coolant flows through the urea tank and urea pump before returning to the engine. For example, the existing patent CN202110373850.6 - An SCR urea heating and defrosting control system and method uses this method. However, the existing technical solutions have the following drawbacks: (1) When the temperature is low, only the coolant thaws and heats the SCR system, resulting in poor thaw and heating capacity. The engine's hot coolant has a certain temperature drop after passing through many pipelines. The engine's coolant not only needs to thaw and heat the urea tank but also needs to thaw and heat the urea pump. The heating effect is poor. The engine coolant has a large temperature drop after flowing through the pipelines and the already frozen urea tank. At this time, the coolant temperature is too low to quickly and effectively thaw and heat the next component, the urea pump. Under certain low ambient temperatures, it is difficult for the engine coolant temperature to rise. From the temperature angle of the engine coolant itself, it is difficult to thaw and heat the urea tank and urea pump. The effect is poor, and it may even be impossible to complete the thaw and heating of the entire system within the specified time, resulting in excessive emissions. It may even cause urea to recrystallize, causing the machine to stop working.

[0003] (2) There is no precise control logic and complete control method. The entire system is controlled by simply opening and closing the water shut-off solenoid valve. The control of the water shut-off solenoid valve is a simple on / off control. When the solenoid valve is open, the temperature of the coolant can only be left to fate and will continue to drop, resulting in poor heating effect. The temperature of the coolant cannot be controlled manually, and the heating rate and heat preservation effect of the urea tank and urea pump cannot be controlled. The coolant not only has to heat the urea tank but also the urea pump, resulting in a large heat loss. The low temperature of the coolant returning to the engine also has a certain impact on the engine operation, causing the engine to be at a low operating temperature throughout the process, thus creating a vicious cycle. In cold conditions, the defrosting and heating time of the SCR system may be greatly extended. Summary of the Invention

[0004] Purpose of the invention: To overcome the shortcomings of the prior art, this invention provides a temperature control system and a temperature control pressure building method for an SCR system. The system and control method of this invention distinguish between cold start and hot start of the machine system. Under hot start, no electrical energy is required to heat the urea pipe, which reduces the energy consumption of the engine. Under cold start, different components are simultaneously thawed and heated by coolant and electric heating. The intensity of thaw heating is high, which can save thaw time under cold conditions, improve efficiency, and make it suitable for various temperature environments.

[0005] Technical Solution: First aspect: This invention provides a temperature control system for an SCR system, comprising: Controller, urea tank, urea pump, pressure pipe, return pipe, intake pipe, temperature acquisition unit in engine ECM, water shut-off solenoid valve; The urea pump has a built-in electric heater and a urea pump temperature sensor. The urea pump temperature sensor is used to collect the temperature data of the urea solution in the urea pump, and the electric heater is used to heat or thaw the urea pump by receiving heating or thawing commands from the controller. The water shut-off solenoid valve is installed in the engine coolant circuit and controls the opening degree of the water shut-off solenoid valve in the engine coolant circuit by receiving the defrosting duty cycle or heating duty cycle signal from the controller. This is used to control the flow rate of the engine coolant circuit to heat or defrost the urea tank. The urea tank is thawed or heated through the engine coolant water circuit. The engine coolant water circuit is controlled by a water shut-off solenoid valve to control its opening and closing. The urea tank is equipped with a urea tank temperature sensor, which is used to collect the temperature data of the urea solution in the urea tank. The engine's ECM acquisition unit collects temperature signals from the ambient temperature sensor, coolant temperature sensor, and SCR front temperature sensor, and feeds back the temperature difference signal between the three to the controller for judging the SCR system status. The suction tube, pressure tube, and return tube are connected in sequence to the urea tank and the urea pump, which are used for the circulation of urea solution between the urea tank and the urea pump. The controller has a preset temperature threshold for the urea pump electric heater; and receives temperature data of the urea solution from the urea pump and urea tank, as well as temperature difference signals from the engine ECM temperature acquisition unit, which are the ambient temperature, coolant temperature, and SCR inlet temperature. The urea solution temperature data is used to determine the current temperature of the urea pump and urea tank; the temperature difference signal is used to determine the SCR system status; and the controller controls the heating or defrosting of the urea pump, urea tank, pressure pipe, return pipe, and suction pipe according to the SCR system status and the current temperature.

[0006] In a further embodiment, the temperature threshold of the urea pump electric heater is used by the controller to output a heating duty cycle signal or a defrosting duty cycle signal to the urea pump electric heater. The temperature thresholds for the urea pump electric heater include: the electric heater thawing shut-off limit, the electric heater heating shut-off limit, the electric heater heating over-temperature limit, the electric heater heating-cooling range limit, and the electric heater heating on-start limit.

[0007] In a further embodiment, the water shut-off solenoid valve is a duty cycle solenoid valve, which controls the water shut-off solenoid valve to achieve the thawing and heating opening of the engine coolant circuit by receiving the thawing duty cycle electrical signal and the heating duty cycle electrical signal output by the controller.

[0008] In a further embodiment, the urea tank is connected to the inlet end of the urea pump via a suction pipe, the outlet end of the urea pump is connected to a pressure pipe, the pressure pipe is connected to the SCR tank, and the SCR tank is connected to the urea tank via a return pipe.

[0009] In a second aspect, the present invention provides a temperature-controlled pressure build-up method, based on the above-described system, comprising: Temperature data of urea pump and urea solution in urea tank, as well as temperature difference signal of temperature acquisition unit in engine ECM, were collected respectively. The SCR system status is determined based on the temperature difference signal, and the current temperature of the urea pump and urea tank is determined based on the temperature data of the urea pump and urea solution in the urea tank, respectively. Select either a cold start or a warm start for the SCR system based on its status. After the SCR system is cold-started or hot-started, the urea pump and urea tank are heated according to their current temperatures, and the temperature data of the urea solution in the urea pump and urea tank are collected in real time during the heating process. Based on the temperature data of the urea pump and urea tank solution, the urea pump, urea tank, pressure pipe, return pipe and suction pipe are selected for thawing, and the thawing completion status of the urea pump, urea tank, pressure pipe, return pipe and suction pipe are monitored during the thawing process. Based on the cold start or hot start method of the SCR system, the thawing completion status of the urea pump, urea tank, pressure pipe, return pipe and suction pipe is selected to determine the completion of SCR system thawing, and the SCR system pressure is built up after the SCR system is thawing.

[0010] In a further embodiment, the method for selecting cold start or warm start of the SCR system based on the SCR system status is as follows: The temperature difference signal from the temperature acquisition unit in the engine ECM is analyzed to determine the SCR system status. The temperature difference signal is calculated by the difference between the ambient temperature, coolant temperature, and SCR inlet temperature. If the temperature difference is less than a preset value, the SCR system status is determined to be in a frozen state, and the cold start SCR system is selected. If the temperature difference is greater than the preset value, the SCR system is determined to be in a non-freezing state, and the hot start SCR system is selected.

[0011] In a further embodiment, after a cold or hot start of the SCR system, the method for heating the urea pump and urea tank according to their current temperatures is as follows: Temperature data of urea solution were collected from the urea pump temperature sensor and the urea tank temperature sensor, respectively. Based on the temperature data of the urea solution from the urea pump temperature sensor and the urea tank temperature sensor, determine the current temperature of the urea pump and the urea tank respectively. Based on the current temperature of the urea tank, the defreezing duty cycle electrical signal or the heating duty cycle signal is output to adjust the opening degree of the water cut-off solenoid valve in the engine coolant circuit; and based on the current temperature of the urea pump, the defreezing duty cycle electrical signal or the heating duty cycle signal is output to control the urea pump heater to turn on.

[0012] In a further embodiment, the method for adjusting the opening degree of the water cut-off solenoid valve in the engine coolant circuit by outputting a defrosting duty cycle electrical signal or a heating duty cycle signal based on the current temperature of the urea tank is as follows: Based on the temperature data of the urea solution from the urea tank temperature sensor, it is determined whether the urea tank needs to be thawed; wherein the temperature data of the urea solution from the urea tank temperature sensor is compared with the thaw start limit to determine the urea tank thaw or heating requirement. Based on the urea tank's defrosting or heating needs, select to output either a defrosting request or a heating request for the urea tank; if the urea tank needs to be defrosted, output a defrosting request; if the urea tank does not need to be defrosted, directly output a heating request. Based on the urea tank's defrosting request, the current temperature of the engine coolant, and the current status of the water shut-off solenoid valve, it is determined whether the urea tank meets the defrosting enable conditions or whether defrosting is necessary. If the urea tank meets the defrosting enable conditions, a defrosting duty cycle signal is output to the water shut-off solenoid valve to control its opening, allowing the engine coolant to defrost the urea tank. The defrosting status of the urea tank is also assessed in real-time based on the urea solution temperature data from the urea tank temperature sensor. If the urea tank does not meet the defrosting enable conditions, defrosting is reassessed. Under the condition that the thawing enable is met, the urea tank enters the thawing state and the thawing completion status of the urea tank is monitored in real time. Based on the urea tank defrosting status, determine and output the urea tank heating request; Based on the urea tank heating request, a heating duty cycle signal is output to the water cut-off solenoid valve to control the opening degree of the water cut-off solenoid valve in the engine coolant water circuit so that the engine coolant water can heat the urea solution in the urea tank.

[0013] In a further embodiment, the method for controlling the urea pump heater to turn on by outputting a defrosting duty cycle electrical signal or a heating duty cycle signal based on the current temperature of the urea pump is as follows: Based on the temperature data of the urea solution from the urea pump temperature sensor, the internal temperature of the urea pump is determined, and the temperature of the electric heater is also collected. Based on the internal temperature of the urea pump and the temperature of the electric heater, a defrosting duty cycle electrical signal or a heating duty cycle signal is selected to be output to the electric heater; this is used to control the electric heater to defrost or heat the urea solution in the urea pump.

[0014] In a further embodiment, the method for selecting whether to output a defrosting duty cycle electrical signal or a heating duty cycle signal to the electric heater based on the internal temperature of the urea pump and the temperature of the electric heater is as follows: The internal temperature of the urea pump is compared with the defrosting shut-off limit of the electric heater to determine whether to output a defrosting duty cycle signal or a heating duty cycle signal to the electric heater. If the internal temperature of the urea pump is less than the defrosting shut-off limit of the electric heater, a defrosting duty cycle signal is output to the electric heater, causing the urea pump to enter the defrosting state. If the internal temperature of the urea pump is greater than or equal to the defrosting shut-off limit of the electric heater, a heating duty cycle signal is output to the electric heater, causing the urea pump to exit the defrosting state and enter the heating state. After outputting a defrosting duty cycle electrical signal to the electric heater, the electric heater defrosts the urea pump and compares the electric heater temperature with the electric heater over-temperature limit during the defrosting process to determine whether the electric heater is in an over-temperature protection state. Based on the determined over-temperature protection status, an over-temperature duty cycle electrical signal is output to the electric heater; upon receiving the over-temperature duty cycle electrical signal, the electric heater cools down until its temperature is below the limit of the heating-cooling range, at which point it outputs a defrosting duty cycle electrical signal to the electric heater again.

[0015] In a further embodiment, if the internal temperature of the urea pump is greater than or equal to the defrosting shut-off limit of the electric heater, outputting a heating duty cycle signal to the electric heater further includes: The electric heater outputs a heating duty cycle signal based on the ambient temperature. It compares the ambient temperature with the heating start limit of the electric heater to determine the heating duty cycle signal to be output to the electric heater. If the ambient temperature is lower than the heating start limit of the electric heater, the heating duty cycle signal is output to the electric heater to heat the urea pump. If the ambient temperature is greater than or equal to the heating start limit of the electric heater, the heating duty cycle signal is turned off. If the ambient temperature is lower than the heating shut-off limit of the electric heater, the heating shut-off duty cycle signal will be output to the electric heater.

[0016] In a further embodiment, based on the cold start or hot start of the SCR system, the method for determining the completion of the SCR system's thawing process by selecting the thawing completion status of the urea pump, urea tank, pressure pipe, return pipe, and suction pipe is as follows: In a cold start SCR system, the SCR system is considered to have completed thawing once the urea pump, urea tank, pressure pipe, return pipe, and suction pipe have all entered the thawing completion state. Specifically, the ambient temperature is used to determine whether the pressure pipe, return pipe, and suction pipe have all entered the thawing completion state. In a hot-start SCR system, the system is considered to have completed thawing once the urea pump and urea tank have entered the thawing completion state.

[0017] In a further embodiment, the method for monitoring the thawing completion status of the urea pump, urea tank, pressure pipe, return pipe, and intake pipe during the thawing process further includes: performing thawing or heating control on the pressure pipe, return pipe, and intake pipe respectively; wherein, the SCR system status is determined based on the temperature difference signal between the ambient temperature, coolant temperature, and SCR inlet temperature fed back by the temperature acquisition unit in the engine ECM. Based on the SCR system status, the system outputs a defrosting duty cycle electrical signal or a heating duty cycle signal to the water shut-off solenoid valve or the urea pump electric heater. This is used to regulate the temperature of the urea solution circulating between the urea pump, urea tank, and SCR tank, and indirectly control the defrosting and heating of the pressure pipe, return pipe, and suction pipe of the circulating urea solution.

[0018] Beneficial effects: Compared with the prior art, the present invention has the following advantages: (1) This invention distinguishes between cold start and hot start of the machine system. Under hot start, no electrical energy is required to heat the urea pipe, which reduces the energy consumption of the engine. Under cold start, different components are simultaneously thawed and heated by coolant and electric heating. The intensity of thaw heating is high, which can save thaw time under cold conditions, improve efficiency, and make it highly applicable to various temperature environments. It ensures that the SCR system completes thaw heating within the time specified by environmental regulations and that the thaw work of the SCR system meets the relevant policies of the environmental protection department.

[0019] (2) The present invention presets multiple control thresholds to perform multi-node control of the electric heater of the urea pump, so that the urea pump can complete the defrosting and heating in a short time, and can also ensure that the urea pump is always in the normal working range under various temperature environments around the world, increasing the diversity of applications and providing a certain protection for the urea pump, that is, protecting the long-term reliability of the urea pump heating. Attached Figure Description

[0020] Figure 1 This is a topology diagram of the temperature control system for an SCR system. Figure 2 Flowchart for pressure build-up in SCR system temperature control; Figure 3 Here is a flowchart of the temperature control process for the urea pump; Figure 4 This is a diagram illustrating an example of how the internal temperature of a urea pump and the electric heater change during thawing. Figure 5 This is an example diagram showing the changes in the electric heater of a urea pump under heating conditions. Detailed Implementation

[0021] To better understand the technical content of the present invention, the technical solution of the present invention will be further introduced and explained below with reference to specific embodiments, but is not limited thereto.

[0022] Example 1: Combination Figure 1 The SCR system temperature control system in this embodiment further includes: a controller, a urea tank, a urea pump, a pressure pipe, a return pipe, a suction pipe, a temperature acquisition unit in the engine ECM, and a water shut-off solenoid valve. The urea pump has a built-in electric heater and a urea pump temperature sensor. The urea pump temperature sensor is used to collect the temperature data of the urea solution in the urea pump, and the electric heater is used to heat or thaw the urea pump by receiving heating or thawing commands from the controller. The water shut-off solenoid valve is installed in the engine coolant circuit and controls the opening degree of the water shut-off solenoid valve in the engine coolant circuit by receiving the defrosting duty cycle or heating duty cycle signal from the controller. This is used to control the flow rate of the engine coolant circuit to heat or defrost the urea tank. The urea tank is thawed or heated through the engine coolant water circuit. The engine coolant water circuit is controlled by a water shut-off solenoid valve to control its opening and closing. The urea tank is equipped with a urea tank temperature sensor, which is used to collect the temperature data of the urea solution in the urea tank. The engine's ECM acquisition unit collects temperature signals from the ambient temperature sensor, coolant temperature sensor, and SCR front temperature sensor, and feeds back the temperature difference signal between the three to the controller for SCR system status determination. The ambient temperature sensor is installed on the vehicle body to collect the ambient temperature outside the vehicle; the coolant temperature sensor is installed on the coolant circuit to collect the coolant temperature; and the SCR front temperature sensor is located at the front of the SCR reaction chamber to collect the exhaust temperature upstream of the SCR system.

[0023] The suction tube, pressure tube, and return tube are connected in sequence to the urea tank and urea pump for the circulation of urea solution between the urea tank and urea pump. The controller has a preset temperature threshold for the urea pump electric heater; and receives temperature data of the urea solution from the urea pump and urea tank, as well as temperature difference signals from the engine ECM temperature acquisition unit, which are the ambient temperature, coolant temperature, and SCR inlet temperature. The urea solution temperature data is used to determine the current temperature of the urea pump and urea tank; the temperature difference signal is used to determine the SCR system status; and the controller controls the heating or defrosting of the urea pump, urea tank, pressure pipe, return pipe, and suction pipe according to the SCR system status and the current temperature.

[0024] Optionally, the temperature threshold of the urea pump electric heater is used by the controller to output the heating duty cycle signal or the defrosting duty cycle signal of the urea pump electric heater. The temperature thresholds for the urea pump electric heater include: the electric heater thawing shut-off limit, the electric heater heating shut-off limit, the electric heater heating over-temperature limit, the electric heater heating-cooling range limit, and the electric heater heating on-start limit.

[0025] Optionally, the water shut-off solenoid valve is a duty cycle solenoid valve, which controls the opening degree of the engine coolant circuit by receiving the defrosting duty cycle electrical signal and the heating duty cycle electrical signal output by the controller.

[0026] refer to Figure 1 The urea tank is connected to the inlet end of the urea pump via a suction pipe, the outlet end of the urea pump is connected to a pressure pipe, the pressure pipe is connected to the SCR tank, and the SCR tank is connected to the urea tank via a return pipe, thereby realizing the urea system pipeline circulation.

[0027] Example 2: like Figure 2This embodiment further illustrates a method for temperature control and pressure build-up in an SCR system, including: Temperature data of urea pump and urea solution in urea tank, as well as temperature difference signal of temperature acquisition unit in engine ECM, were collected respectively. The SCR system status is determined based on the temperature difference signal, and the current temperature of the urea pump and urea tank is determined based on the temperature data of the urea pump and urea solution in the urea tank, respectively. Select either a cold start or a warm start for the SCR system based on its status. After the SCR system is cold-started or hot-started, the urea pump and urea tank are heated according to their current temperatures, and the temperature data of the urea solution in the urea pump and urea tank are collected in real time during the heating process. Based on the temperature data of the urea pump and urea tank solution, the urea pump, urea tank, pressure pipe, return pipe and suction pipe are selected for thawing, and the thawing completion status of the urea pump, urea tank, pressure pipe, return pipe and suction pipe are monitored during the thawing process. Based on the cold start or hot start method of the SCR system, the thawing completion status of the urea pump, urea tank, pressure pipe, return pipe and suction pipe is selected to determine the completion of SCR system thawing, and the SCR system pressure is built up after the SCR system is thawing.

[0028] Optionally, the method for selecting cold start or warm start of the SCR system based on the SCR system status is as follows: The temperature difference signal of the temperature acquisition unit in the engine ECM is analyzed to determine the SCR system status. The temperature difference signal is calculated by the difference between the ambient temperature, coolant temperature and SCR inlet temperature. If the temperature difference is less than 15°C, the SCR system status is determined to be frozen, and the cold start SCR system is selected. If the temperature difference is greater than the preset value of 15°, the SCR system is determined to be in a non-freezing state, and the hot start SCR system is selected. Furthermore, the temperature difference signal is calculated and output by the difference between the ambient temperature, coolant temperature, and SCR inlet temperature. Specifically, the maximum and minimum values ​​of the ambient temperature, coolant temperature, and SCR inlet temperature are taken. If the difference between the maximum and minimum values ​​is less than 15°, it is a cold start; otherwise, it is a hot start.

[0029] Optionally, after the SCR system has been cold or hot started, the combination of urea pump and urea tank is heated according to the current temperature of the urea pump and urea tank. The urea heating process is divided into three stages. Phase 1: Thawing – Maximize heating power to melt the urea in the SCR system to prepare for normal pressure build-up in the shortest possible time; Second stage: Heating – Reduce heating power to keep the system in thermal equilibrium and prevent it from refreezing; Phase 3: Shutdown – When the relevant temperature or boundary conditions are met, the heating function is turned off.

[0030] The method for heating the urea pump and urea tank based on their current temperatures is as follows: Temperature data of urea solution were collected from the urea pump temperature sensor and the urea tank temperature sensor, respectively. Based on the temperature data of the urea solution from the urea pump temperature sensor and the urea tank temperature sensor, determine the current temperature of the urea pump and the urea tank respectively. Based on the current temperature of the urea tank, the opening degree of the water cut-off solenoid valve in the engine coolant circuit is adjusted by outputting a defrosting duty cycle electrical signal or a heating duty cycle signal; and based on the current temperature of the urea pump, the defrosting duty cycle electrical signal or a heating duty cycle signal is output to control the urea pump heater to turn on. In this embodiment, both the urea pump and the urea tank enter the first stage.

[0031] Optionally, when the urea tank enters the first stage, the method for adjusting the opening degree of the water cut-off solenoid valve in the engine coolant circuit by outputting a defrosting duty cycle electrical signal or a heating duty cycle signal according to the current temperature of the urea tank is as follows: Based on the temperature data of the urea solution from the urea tank temperature sensor, it is determined whether the urea tank needs to be thawed; specifically, the temperature data of the urea solution from the urea tank temperature sensor is compared with the thawing start limit to determine whether the urea tank needs to be thawed or heated. Based on the urea tank's defrosting or heating needs, select to output either a defrosting request or a heating request for the urea tank; if the urea tank needs to be defrosted, output a defrosting request; if the urea tank does not need to be defrosted, directly output a heating request. Based on the urea tank's defrosting request, the current temperature of the engine coolant, and the current status of the water shut-off solenoid valve, it is determined whether the urea tank meets the defrosting enable conditions or whether defrosting is necessary. If the urea tank meets the defrosting enable conditions, a defrosting duty cycle signal is output to the water shut-off solenoid valve to control its opening, allowing the engine coolant to defrost the urea tank. The defrosting status of the urea tank is also assessed in real-time based on the urea solution temperature data from the urea tank temperature sensor. If the urea tank does not meet the defrosting enable conditions, defrosting is reassessed. Under the condition that the thawing enable is met, the urea tank enters the thawing state and the thawing completion status of the urea tank is monitored in real time. Based on the urea tank defrosting status, determine and output the urea tank heating request; According to the urea tank heating request, a heating duty cycle signal is output to the water cut-off solenoid valve to control the opening of the water cut-off solenoid valve in the engine coolant water circuit so that the engine coolant water can heat the urea solution in the urea tank; in this embodiment, the urea tank precisely controls the thawing and heat preservation of the urea solution in the urea tank through the water cut-off solenoid valve.

[0032] Optionally, when the urea pump enters the first stage, the method of controlling the urea pump heater to start by outputting a defrosting duty cycle electrical signal or a heating duty cycle signal based on the current temperature of the urea pump is as follows: Based on the temperature data of the urea solution from the urea pump temperature sensor, the internal temperature of the urea pump is determined, and the temperature of the electric heater is also collected. Based on the internal temperature of the urea pump and the temperature of the electric heater, a defrosting duty cycle electrical signal or a heating duty cycle signal is selected to be output to the electric heater; this is used to control the electric heater to defrost or heat the urea solution in the urea pump.

[0033] Optionally, when the urea pump sequentially enters the second and third stages from the first stage, the method of selecting to output a defrosting duty cycle electrical signal or a heating duty cycle signal to the electric heater based on the internal temperature of the urea pump and the temperature of the electric heater is as follows: The internal temperature of the urea pump is compared with the defrosting shut-off limit of the electric heater to determine whether to output a defrosting duty cycle signal or a heating duty cycle signal to the electric heater. If the internal temperature of the urea pump is less than the defrosting shut-off limit of the electric heater, a defrosting duty cycle signal is output to the electric heater, causing the urea pump to enter the defrosting state. If the internal temperature of the urea pump is greater than or equal to the defrosting shut-off limit of the electric heater, a heating duty cycle signal is output to the electric heater, causing the urea pump to exit the defrosting state and enter the heating state. When moving from the first stage to the second stage, after outputting a defrosting duty cycle electrical signal to the electric heater, the electric heater defrosts the urea pump. During the defrosting process, the temperature of the electric heater is compared with the over-temperature limit of the electric heater to determine whether the electric heater is in an over-temperature protection state. Based on the determined over-temperature protection status, an over-temperature duty cycle electrical signal is output to the electric heater. Upon receiving the over-temperature duty cycle electrical signal, the electric heater cools down until its temperature is below the limit of the heating-cooling range. Then, a defrosting duty cycle electrical signal is output to the electric heater again. In this embodiment, the power of the urea pump electric heater exhibits a heating-reducing heating power change trend, keeping the system in thermal balance and preventing it from refreezing. Furthermore, when transitioning from the second stage to the third stage, if the internal temperature of the urea pump is greater than or equal to the defrosting shut-off limit of the electric heater, the output of the heating duty cycle signal to the electric heater also includes: The electric heater outputs a heating duty cycle signal based on the ambient temperature. It compares the ambient temperature with the heating start limit of the electric heater to determine the heating duty cycle signal to be output to the electric heater. If the ambient temperature is lower than the heating start limit of the electric heater, the heating duty cycle signal is output to the electric heater to heat the urea pump. If the ambient temperature is greater than or equal to the heating start limit of the electric heater, the heating duty cycle signal is turned off. If the ambient temperature is lower than the heating shut-off limit of the electric heater, the shut-off duty cycle signal is output to the electric heater; in this embodiment, the urea pump electric heater meets the shut-off-related temperature or boundary conditions, thereby shutting off the electric heater heating function.

[0034] In a further embodiment, based on the cold start or hot start of the SCR system, the method for determining the completion of the SCR system's thawing process by selecting the thawing completion status of the urea pump, urea tank, pressure pipe, return pipe, and suction pipe is as follows: In a cold start SCR system, the SCR system is considered to have completed thawing once the urea pump, urea tank, pressure pipe, return pipe, and suction pipe have all entered the thawing completion state. Specifically, the ambient temperature is used to determine whether the pressure pipe, return pipe, and suction pipe have all entered the thawing completion state. In a hot-start SCR system, the system is considered to have completed thawing once the urea pump and urea tank have entered the thawing completion state.

[0035] Optionally, the method for monitoring the defrosting completion status of the urea pump, urea tank, pressure pipe, return pipe, and intake pipe during the defrosting process also includes: separately controlling the defrosting or heating of the pressure pipe, return pipe, and intake pipe; wherein, the SCR system status is determined based on the temperature difference signal between the ambient temperature, coolant temperature, and SCR inlet temperature fed back by the temperature acquisition unit in the engine ECM. Based on the SCR system status, the system outputs a defrosting duty cycle electrical signal or a heating duty cycle signal to the water shut-off solenoid valve or the urea pump electric heater. This is used to regulate the temperature of the urea solution circulating between the urea pump, urea tank, and SCR tank, and indirectly control the defrosting and heating of the pressure pipe, return pipe, and suction pipe of the circulating urea solution.

[0036] In summary, this invention distinguishes between cold and hot starts in the machine system. During a hot start, no electrical energy is required to heat the urea pipe, reducing engine energy consumption. During a cold start, both coolant and electric heating simultaneously perform defrosting heating on different components, resulting in high-intensity defrosting heating that saves defrosting time in cold conditions, improving efficiency and making it highly suitable for various temperature environments. It ensures the SCR system completes defrosting heating within the timeframe stipulated by environmental regulations, ensuring the SCR system's defrosting operation complies with relevant environmental policies. This invention presets multiple control thresholds for multi-node control of the urea pump's electric heater, enabling the urea pump to complete defrosting heating quickly and ensuring it remains within its normal operating range under diverse temperature conditions throughout the day. This increases applicability while providing protection for the urea pump, ensuring long-term reliability of its heating process.

[0037] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0038] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0039] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0040] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0041] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for temperature control and pressure build-up in an SCR system, characterized in that, A temperature control system for an SCR system includes: Controller, urea tank, urea pump, pressure pipe, return pipe, intake pipe, temperature acquisition unit in engine ECM, water shut-off solenoid valve; The urea pump has a built-in electric heater and a urea pump temperature sensor. The urea pump temperature sensor is used to collect the temperature data of the urea solution in the urea pump, and the electric heater is used to heat or thaw the urea pump by receiving heating or thawing commands from the controller. The water shut-off solenoid valve is installed in the engine coolant circuit and controls the opening degree of the water shut-off solenoid valve in the engine coolant circuit by receiving the defrosting duty cycle or heating duty cycle signal from the controller. This is used to control the flow rate of the engine coolant circuit to heat or defrost the urea tank. The urea tank is thawed or heated through the engine coolant water circuit. The engine coolant water circuit is controlled by a water shut-off solenoid valve to control its opening and closing. The urea tank is equipped with a urea tank temperature sensor, which is used to collect the temperature data of the urea solution in the urea tank. The urea tank is connected to the inlet end of the urea pump via a suction pipe, the outlet end of the urea pump is connected to a pressure pipe, the pressure pipe is connected to the SCR tank, and the SCR tank is connected to the urea tank via a return pipe. The controller has a preset temperature threshold for the urea pump electric heater; and receives temperature data of the urea solution from the urea pump and urea tank, as well as temperature difference signals from the engine ECM temperature acquisition unit, including ambient temperature, coolant temperature, and SCR inlet temperature. The urea solution temperature data is used to determine the current temperature of the urea pump and urea tank; the temperature difference signal is used to determine the SCR system status; and the controller controls the heating or defrosting of the urea pump, urea tank, pressure pipe, return pipe, and suction pipe based on the SCR system status and current temperature. The method includes: Temperature data of urea pump and urea solution in urea tank, as well as temperature difference signal of temperature acquisition unit in engine ECM, were collected respectively. The SCR system status is determined based on the temperature difference signal, and the current temperature of the urea pump and urea tank is determined based on the temperature data of the urea pump and urea tank solution, respectively. The temperature difference signal from the temperature acquisition unit in the engine ECM is analyzed to determine the SCR system status. The temperature difference signal is calculated by the difference between the maximum and minimum values ​​of the ambient temperature, coolant temperature, and SCR inlet temperature. If the temperature difference is less than a preset value, the SCR system status is determined to be in a frozen state, and a cold start SCR system is selected. If the temperature difference is greater than the preset value, the SCR system is determined to be in a non-freezing state, and the hot start SCR system is selected. After the SCR system is cold-started or hot-started, the urea pump and urea tank are heated according to their current temperatures, and the temperature data of the urea solution in the urea pump and urea tank are collected in real time during the heating process. Based on the temperature data of the urea pump and urea tank solution, the urea pump, urea tank, pressure pipe, return pipe and suction pipe are selected for thawing, and the thawing completion status of the urea pump, urea tank, pressure pipe, return pipe and suction pipe are monitored during the thawing process. In a cold start SCR system, the SCR system is considered to have completed thawing once the urea pump, urea tank, pressure pipe, return pipe, and suction pipe have all entered the thawing completion state. Specifically, the ambient temperature is used to determine whether the pressure pipe, return pipe, and suction pipe have all entered the thawing completion state. In a hot-start SCR system, once the urea pump and urea tank have entered the defrosting completed state, the defrosting of the SCR system is confirmed to be complete. After the SCR system defrosts, pressure is built up in the SCR system. Thus, in a hot-start SCR system, no electrical energy is required to heat the urea pipes. In a cold start, defrosting and heating of different components are performed simultaneously through coolant and electric heating.

2. The SCR system temperature control pressure build-up method according to claim 1, characterized in that, The temperature threshold of the urea pump electric heater is used by the controller to output the heating duty cycle signal or the defrosting duty cycle signal of the urea pump electric heater. The temperature thresholds for the urea pump electric heater include: the electric heater thawing shut-off limit, the electric heater heating shut-off limit, the electric heater heating over-temperature limit, the electric heater heating-cooling range limit, and the electric heater heating on-start limit.

3. The SCR system temperature control pressure build-up method according to claim 1, characterized in that, The water shut-off solenoid valve is a duty cycle solenoid valve. It controls the opening degree of the engine coolant circuit by receiving the defrosting duty cycle electrical signal and the heating duty cycle electrical signal output by the controller.

4. The SCR system temperature control pressure build-up method according to claim 1, characterized in that, After a cold or hot start of the SCR system, the method for heating the urea pump and urea tank based on their current temperatures is as follows: Temperature data of urea solution were collected from the urea pump temperature sensor and the urea tank temperature sensor, respectively. Based on the temperature data of the urea solution from the urea pump temperature sensor and the urea tank temperature sensor, determine the current temperature of the urea pump and the urea tank respectively. Based on the current temperature of the urea tank, the defreezing duty cycle electrical signal or the heating duty cycle electrical signal is output to adjust the opening degree of the water cut-off solenoid valve in the engine coolant circuit; and based on the current temperature of the urea pump, the defreezing duty cycle electrical signal or the heating duty cycle electrical signal is output to control the urea pump electric heater to turn on.

5. The SCR system temperature control pressure build-up method according to claim 4, characterized in that, The method for adjusting the opening degree of the water cut-off solenoid valve in the engine coolant circuit based on the current temperature of the urea tank, by outputting a defrosting duty cycle electrical signal or a heating duty cycle signal, is as follows: Based on the temperature data of the urea solution from the urea tank temperature sensor, it is determined whether the urea tank needs to be thawed; wherein the temperature data of the urea solution from the urea tank temperature sensor is compared with the thaw start limit to determine the urea tank thaw or heating requirement. Based on the urea tank's defrosting or heating needs, select to output either a defrosting request or a heating request for the urea tank; if the urea tank needs to be defrosted, output a defrosting request; if the urea tank does not need to be defrosted, directly output a heating request. Based on the urea tank's defrosting request, the current temperature of the engine coolant, and the current status of the water shut-off solenoid valve, it is determined whether the urea tank meets the defrosting enable conditions or whether defrosting is necessary. If the urea tank meets the defrosting enable conditions, a defrosting duty cycle signal is output to the water shut-off solenoid valve to control its opening, allowing the engine coolant to defrost the urea tank. The defrosting status of the urea tank is also assessed in real-time based on the urea solution temperature data from the urea tank temperature sensor. If the urea tank does not meet the defrosting enable conditions, defrosting is reassessed. Under the condition that the thawing enable is met, the urea tank enters the thawing state and the thawing completion status of the urea tank is monitored in real time. Based on the urea tank defrosting status, determine and output the urea tank heating request; Based on the urea tank heating request, a heating duty cycle signal is output to the water cut-off solenoid valve to control the opening degree of the water cut-off solenoid valve in the engine coolant water circuit so that the engine coolant water can heat the urea solution in the urea tank.

6. The SCR system temperature control pressure build-up method according to claim 5, characterized in that, The method for controlling the urea pump heater to start based on the current temperature of the urea pump is as follows: (This is the method for outputting a defrosting duty cycle electrical signal or a heating duty cycle signal.) Based on the temperature data of the urea solution from the urea pump temperature sensor, the internal temperature of the urea pump is determined, and the temperature of the electric heater is also collected. Based on the internal temperature of the urea pump and the temperature of the electric heater, a defrosting duty cycle electrical signal or a heating duty cycle signal is selected to be output to the electric heater; this is used to control the electric heater to defrost or heat the urea solution in the urea pump.

7. The SCR system temperature control pressure build-up method according to claim 6, characterized in that, Based on the internal temperature of the urea pump and the temperature of the electric heater, the method for selecting whether to output a defrosting duty cycle electrical signal or a heating duty cycle signal to the electric heater is as follows: The internal temperature of the urea pump is compared with the defrosting shut-off limit of the electric heater to determine whether to output a defrosting duty cycle signal or a heating duty cycle signal to the electric heater. If the internal temperature of the urea pump is less than the defrosting shut-off limit of the electric heater, a defrosting duty cycle signal is output to the electric heater, causing the urea pump to enter the defrosting state. If the internal temperature of the urea pump is greater than or equal to the defrosting shut-off limit of the electric heater, a heating duty cycle signal is output to the electric heater, causing the urea pump to exit the defrosting state and enter the heating state. After outputting a defrosting duty cycle electrical signal to the electric heater, the electric heater defrosts the urea pump and compares the electric heater temperature with the electric heater over-temperature limit during the defrosting process to determine whether the electric heater is in an over-temperature protection state. Based on the determined over-temperature protection status, output an electric signal for the electric heater's over-temperature duty cycle to the electric heater; The electric heater cools down after receiving the overheat duty cycle electrical signal until the temperature of the electric heater is lower than the limit of the heating and cooling range. Then, it outputs the defrost duty cycle electrical signal to the electric heater again.

8. The SCR system temperature control pressure build-up method according to claim 7, characterized in that, If the internal temperature of the urea pump is greater than or equal to the defrosting shut-off limit of the electric heater, the heating duty cycle signal output to the electric heater also includes: The electric heater outputs a heating duty cycle signal based on the ambient temperature. It compares the ambient temperature with the heating start limit of the electric heater to determine the heating duty cycle signal to be output to the electric heater. If the ambient temperature is lower than the heating start limit of the electric heater, the heating duty cycle signal is output to the electric heater to heat the urea pump. If the ambient temperature is greater than or equal to the heating start limit of the electric heater, the heating duty cycle signal is turned off. If the ambient temperature is lower than the heating shut-off limit of the electric heater, the heating shut-off duty cycle signal will be output to the electric heater.

9. The SCR system temperature control pressure build-up method according to claim 1, characterized in that, The method for monitoring the thawing completion status of the urea pump, urea tank, pressure pipe, return pipe, and intake pipe during the thawing process also includes: thawing or heating control of the pressure pipe, return pipe, and intake pipe respectively; wherein, the SCR system status is determined based on the temperature difference signal between the ambient temperature, coolant temperature, and SCR inlet temperature fed back by the temperature acquisition unit in the engine ECM. Based on the SCR system status, the system outputs a defrosting duty cycle electrical signal or a heating duty cycle signal to the water shut-off solenoid valve or the urea pump electric heater. This is used to regulate the temperature of the urea solution circulating between the urea pump, urea tank, and SCR tank, and indirectly control the defrosting and heating of the pressure pipe, return pipe, and suction pipe of the circulating urea solution.

Images