Urea supply injection system with dual injection function and control method thereof

Abstract

The present application provides a urea supply and injection system with dual injection function and a control method thereof, wherein the system includes a urea supply device, an air-assist device and a mixing chamber, wherein the urea supply device and the air-assist device are respectively connected to the inlet end of the mixing chamber; the urea supply device is used to provide urea liquid into the mixing chamber; the air-assist device is used to provide compressed air into the mixing chamber to assist in the injection of urea liquid; the outlet end of the mixing chamber is connected to two injection pipelines, which are arranged in parallel and are respectively connected to the ccSCR device and the SCR device; a constant pressure reducing valve and a second solenoid valve are sequentially arranged on the injection pipeline from the end close to the mixing chamber to the end away from the mixing chamber, and the constant pressure reducing valve is used to control the pressure in the injection pipeline. The urea supply and injection system with dual injection function provided by the present application has a simple structure and can realize that the two injection pipelines can independently and accurately meet various working conditions.

Description

Technical Field

[0001] The present disclosure generally relates to the field of vehicle aftertreatment control technology, and more particularly to a urea supply and injection system with dual injection functions and a control method thereof. Background Art

[0002] SCR (Selective Catalytic Reduction) is an essential aftertreatment device in current vehicles. However, with increasingly stringent emissions regulations, conventional SCR systems struggle to meet the China VII emission standards expected to be issued in the coming years. Numerous studies, both domestic and international, have shown that adding a ccSCR (close-coupled Selective Catalytic Reduction) system to the aftertreatment stage is a promising solution. This requires two urea injection systems to provide the catalyst.

[0003] However, there are some problems with the three existing urea supply and injection systems: the first is to configure an independent urea supply and injection system for each SCR device. This solution will cause the urea supply and injection system to occupy too much space and incur high costs; the second is to use two urea pumping systems to control the corresponding injection respectively, such as the patent number: CN202220385900.2, and the patent name: A two-stage injection urea metering pump. This solution only avoids the use of two urea tanks, and the other internal structures are still two sets of relative urea supply devices, which are complex in structure and high in cost; the third is to use one urea pumping system to supply two sets of urea injection units, such as the patent number CN202110891201.5, and the patent name: An invention patent for a urea supply and injection system with a two-stage injection function, but the two injection units in this solution interfere with each other greatly, and the injection amount cannot be accurately controlled. Summary of the Invention

[0004] In view of the above-mentioned defects or deficiencies in the prior art, it is desired to provide a urea supply injection system with a dual injection function and a control method thereof to solve the above-mentioned problems.

[0005] In a first aspect, the present application provides a urea supply and injection system with dual injection functions, comprising a urea supply device, an air assist device, and a mixing chamber, wherein the urea supply device and the air assist device are respectively connected to an inlet end of the mixing chamber; the urea supply device is used to supply urea liquid into the mixing chamber; and the air assist device is used to supply compressed air into the mixing chamber to assist in injection of the urea liquid.

[0006] The outlet end of the mixing chamber is connected to two injection pipelines, which are arranged in parallel and are respectively connected to the ccSCR device and the SCR device; a constant pressure reducing valve and a second solenoid valve are sequentially arranged on the injection pipeline from one end close to the mixing chamber to the end away from the mixing chamber, and the constant pressure reducing valve is used to control the pressure in the injection pipeline.

[0007] According to the technical solution provided in the embodiment of the present application, the urea supply device includes a urea tank and a urea pipeline, wherein the urea tank contains urea liquid; the urea pipeline includes a first port and a second port, both of which are connected to the urea tank; a liquid inlet filter, a first one-way valve, a urea pump and a first solenoid valve are sequentially arranged between the first port and the second port; the urea pipeline is further provided with an external interface between the urea pump and the first solenoid valve, wherein the external interface is connected to the mixing chamber; and a reversing valve is arranged between the external interface and the mixing chamber.

[0008] According to the technical solution provided in the embodiment of the present application, the first port is below the urea liquid level, and the second port is above the urea liquid level.

[0009] According to the technical solution provided in the embodiment of the present application, the air-assisting device includes a compressed air tank and an air pipeline, one end of the air pipeline is connected to the compressed air tank, and the other end is connected to the mixing chamber; the air pipeline is connected in sequence to an air filter, a second one-way valve, an air pump and a throttle valve.

[0010] According to the technical solution provided in the embodiment of the present application, a urea heating device is also included, which includes a circulating water pipeline and a third solenoid valve. The water inlet end of the circulating water pipeline is connected to the water outlet pipe of the engine cooling circulating water, and the water outlet end of the circulating water pipeline is connected to the water inlet pipe of the engine cooling circulating water; the third solenoid valve is arranged at the water inlet end of the circulating water pipeline; the circulating water pipeline includes a first heating part, a second heating part and a third heating part connected in sequence, the first heating part and the third heating part are respectively used to heat the two injection pipelines, and the second heating part is used to heat the urea tank.

[0011] According to the technical solution provided in the embodiment of the present application, the first heating part and the third heating part are spirally wrapped around the two injection pipelines respectively.

[0012] According to the technical solution provided in the embodiment of the present application, the second heating part extends into the urea tank and is densely distributed in a spiral shape in the urea tank.

[0013] According to the technical solution provided in the embodiment of the present application, a first pressure sensor is provided between the urea pump and the external interface for detecting the pressure of the urea liquid; a second pressure sensor is provided between the air pump and the mixing chamber for detecting the pressure of the compressed air; and a third pressure sensor is provided between the second solenoid valve and the nozzle for detecting the pressure of the gas-liquid mixture.

[0014] According to the technical solution provided in the embodiment of the present application, a liquid level sensor is provided in the urea tank.

[0015] A second aspect of the present application provides an injection system control method for controlling the urea supply injection system with dual injection function as described above, comprising the following steps:

[0016] adjusting the two constant pressure reducing valves according to the pressure requirements of the ccSCR device and the SCR device in the injection pipeline;

[0017] closing the first solenoid valve;

[0018] turning on the urea supply device and the air assist device;

[0019] When urea needs to be supplied to the ccSCR device, a second solenoid valve on the injection line connected to the ccSCR device is opened;

[0020] When urea needs to be supplied to the SCR device, the second solenoid valve on the injection line communicating with the SCR device is opened.

[0021] Compared with the prior art, the present application has the following advantages: by providing two injection pipelines and arranging the two injection pipelines in parallel, urea can be supplied to the ccSCR device and the SCR device respectively by the two injection pipelines; by sharing a set of the urea supply device and the air assist device for the two injection pipelines and communicating them through a mixing chamber, the overall system has a higher degree of integration, a smaller volume, and can save more installation space while reducing production costs; by arranging a constant pressure reducing valve at the starting position of the injection pipeline, it is ensured that the pressures in the two injection pipelines do not affect each other, that is, when one injection pipeline is opened or closed, the pressure in the other injection pipeline does not change with the opening or closing of the other injection pipeline, thereby always maintaining the stability of the pressure in the injection pipeline and improving the urea supply efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Other features, objects and advantages of the present application will become more apparent upon reading the detailed description of non-limiting embodiments made with reference to the following drawings:

[0023] Figure 1This is a schematic structural diagram of a urea supply and injection system with dual injection functions provided in Example 1 of the present application;

[0024] Figure 2 A flowchart of the steps of the control method of the injection system provided in Example 2 of the present application;

[0025] Reference numerals: 101, urea tank; 102, urea pipeline; 103, liquid inlet filter; 104, first one-way valve; 105, urea pump; 106, first solenoid valve; 107, external interface; 108, first pressure sensor; 109, reversing valve; 110, liquid level sensor; 201, air tank; 202, air pipeline; 203, air filter; 204, second one-way valve; 205, air pump; 206, throttle valve; 207, second pressure sensor; 301, mixing chamber; 302, injection pipeline; 303, constant-pressure reducing valve; 304, second solenoid valve; 305, nozzle; 306, third pressure sensor; 401, circulating water pipeline; 402, third solenoid valve. DETAILED DESCRIPTION

[0026] The present application will be further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are merely for the purpose of explaining the relevant invention and are not intended to limit the invention. It should also be noted that, for ease of description, only portions relevant to the invention are shown in the accompanying drawings.

[0027] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0028] Example 1

[0029] Please refer to Figure 1 The present application provides a urea supply and injection system with dual injection functions, comprising a urea supply device, an air assist device, and a mixing chamber 301. The urea supply device and the air assist device are respectively connected to the inlet end of the mixing chamber 301. The urea supply device is used to supply urea liquid into the mixing chamber 301. The air assist device is used to supply compressed air into the mixing chamber 301 to assist in the injection of the urea liquid.

[0030] The outlet end of the mixing chamber 301 is connected to two injection pipes 302, which are arranged in parallel and are connected to the ccSCR device and the SCR device respectively; a constant pressure reducing valve 303 and a second solenoid valve 304 are sequentially arranged on the injection pipe 302 from the end close to the mixing chamber 301 to the end away from the mixing chamber 301, and the constant pressure reducing valve 303 is used to control the pressure in the injection pipe 302.

[0031] Specifically, two injection pipelines 302 are provided in parallel, and the two injection pipelines 302 are used to provide urea to the ccSCR device and the SCR device respectively; the constant-pressure reducing valve 303 is provided at one end of the injection pipeline 302 for the entry of the gas-liquid mixture, and the constant-pressure reducing valve 303 is used to ensure that the pressure in the injection pipeline 302 is controlled, that is, when only one injection pipeline 302 is needed to work, regardless of whether the other injection pipeline 302 is opened or not, the pressure in the injection pipeline 302 can remain unchanged, thereby improving the supply efficiency of urea; a nozzle 305 is provided at one end of the injection pipeline 302 for the discharge of the gas-liquid mixture, and the nozzle 305 is connected to the ccSCR device or the SCR device; the second solenoid valve is provided between the constant-pressure reducing valve 303 and the nozzle 305, and is used to control the opening and closing of the injection pipeline 302.

[0032] Working principle: By setting up two injection pipelines 302 and setting the two injection pipelines 302 in parallel, the two injection pipelines 302 can be used to supply urea to the ccSCR device and the SCR device respectively; by the two injection pipelines 302 sharing a set of the urea supply device and the air assist device and connecting them through the mixing chamber 301, the overall integration of the system is higher, the volume is smaller, and more installation space can be saved, while reducing production costs; by setting a constant pressure reducing valve 303 at the starting position of the injection pipeline 302, it is ensured that the pressures of the two injection pipelines 302 do not affect each other, that is, when one injection pipeline 302 is opened or closed, the pressure in the other injection pipeline 302 will not change with the opening or closing of the other injection pipeline 302, and the stability of the pressure in the injection pipeline 302 is always maintained, thereby improving the urea supply efficiency.

[0033] In a preferred embodiment, the urea supply device includes a urea tank 101 and a urea pipeline 102. The urea tank 101 contains urea liquid. The urea pipeline 102 includes a first port and a second port, both of which are connected to the urea tank 101. A liquid inlet filter 103, a first one-way valve 104, a urea pump 105, and a first solenoid valve 106 are sequentially provided between the first port and the second port. The urea pipeline 102 is further provided with an external port 107 between the urea pump 105 and the first solenoid valve 106. The external port 107 is connected to the mixing chamber 301. A reversing valve 109 is provided between the external port 107 and the mixing chamber 301.

[0034] Specifically, the first port serves as the inlet of the urea liquid, and the second port serves as the outlet of the urea liquid; a reversing valve 109 is provided between the external port 107 and the mixing chamber 301; the inlet filter 103 is used to filter impurities in the urea liquid to protect subsequent components; the urea pump 105 is used to extract urea liquid from the urea tank 101; the first one-way valve 104 is connected from the first port to the second port to control the flow direction of the urea liquid; the first solenoid valve 106 is used to control the opening and closing of the second port and the urea tank 101. When the first solenoid valve 106 is opened, if the urea pump When the first solenoid valve 106 is closed and the urea pump 105 starts working, the urea liquid entering the urea pipe 102 will flow back into the urea tank 101 through the second port under the action of the urea pump 105; when the first solenoid valve 106 is closed and the urea pump 105 starts working, the urea liquid entering the urea pipe 102 will not flow back into the urea tank 101 through the second port under the action of the urea pump 105, and the urea liquid will enter the mixing chamber 301 through the external port 107 via the reversing valve 109. Note that at this time, the conducting direction of the reversing valve 109 should be from the external port 107 to the mixing chamber 301.

[0035] In a preferred embodiment, the first port is located below the urea liquid level, and the second port is located above the urea liquid level.

[0036] Specifically, the first port is placed below the urea liquid level in order to facilitate the suction of urea liquid into the urea pipe 102 by the urea pump 105. The second port is placed below the urea liquid level because the first solenoid valve 106 is always in a closed state during the injection of urea liquid. If the second port is placed below the urea liquid level, the urea liquid in the second port cannot maintain flow, making it easy for urea to crystallize at the second port, thereby blocking the second port.

[0037] In a preferred embodiment, the air assist device includes a compressed air tank 201 and an air pipeline 202, one end of the air pipeline 202 is connected to the compressed air tank 201, and the other end is connected to the mixing chamber 301; the air pipeline 202 is sequentially connected to an air filter 203, a second one-way valve 204, an air pump 205 and a throttle valve 206.

[0038] Specifically, the air filter 203, the second one-way valve 204, the air pump 205 and the throttle valve 206 are arranged on the air pipeline 202, and are arranged in sequence from the end of the air pipeline 202 close to the air tank 201 to the end away from the air tank 201; the air filter 203 is used to filter particulate impurities in the air, thereby protecting subsequent components; the second one-way valve 204 is used to prevent urea liquid in the urea pipeline 102 from entering the compressed air tank 201, and at the same time prevent gas backflow; the air pump 205 sucks the air in the air tank 201 into the air pipeline 202, and pressurizes the air and delivers it to the mixing chamber 301, thereby increasing the pressure of the gas-liquid mixture in the mixing chamber 301 to assist urea injection; the throttle valve 206 is used to ensure the stability of the air pressure.

[0039] Specifically, in addition to assisting urea injection, the air assist device can also clean the urea pipeline 102 and the injection pipeline 302 through compressed air to prevent urea from crystallizing in the pipeline and causing pipeline blockage.

[0040] In a preferred embodiment, a urea heating device is further provided, which includes a circulating water pipeline 401 and a third solenoid valve 402. The water inlet end of the circulating water pipeline 401 is connected to the water outlet pipe of the engine cooling circulating water, and the water outlet end of the circulating water pipeline 401 is connected to the water inlet pipe of the engine cooling circulating water; the third solenoid valve 402 is arranged at the water inlet end of the circulating water pipeline 401; the circulating water pipeline 401 includes a first heating part, a second heating part and a third heating part connected in sequence, the first heating part and the third heating part are respectively used to heat the two injection pipelines 302, and the second heating part is used to heat the urea tank 101.

[0041] Specifically, the first, second, and third heating units are arranged sequentially from one end of the engine cooling circulating water outlet pipe to the end away from the outlet pipe. The first and third heating units are positioned in close proximity to the injection pipe 302, while the second heating unit extends into the urea tank 101. The circulating water pipe 401 operates by transferring high-temperature cooling water, after engine cooling, to the two injection pipes 302 and the urea tank 101, respectively. The high temperature of the high-temperature cooling water heats the urea liquid in the injection pipes 302 and the gas-liquid mixture in the urea tank 101, preventing urea crystallization and line blockage. The third solenoid valve 402 is positioned between the first heating unit and the engine cooling circulating water outlet pipe to control the flow of water between the first heating unit and the outlet pipe.

[0042] In a preferred embodiment, the first heating portion and the third heating portion are spirally wound around the two injection pipelines 302 respectively.

[0043] By arranging the first heating part and the third heating part to spirally surround the two injection pipes 302, the contact area with the first heating part and the third heating part is increased as much as possible on the basis of a certain length of the injection pipe 302, thereby improving the heating efficiency of the gas-liquid mixture in the injection pipe 302.

[0044] In a preferred embodiment, the second heating parts extend into the urea tank 101 and are densely distributed in a spiral shape in the urea tank 101 .

[0045] By extending the second heating portion into the urea tank 101 and coiling and densely arranged in a spiral shape, the contact area between the second heating portion and the urea liquid is increased, thereby improving the heating efficiency of the urea liquid in the urea tank 101 .

[0046] In another embodiment, the urea heating device may be replaced with an electric heating plate, and the electric heating plate is used to directly heat the urea liquid in the injection pipe 302 and the urea tank 101; when the heating device is replaced with the electric heating plate, the third solenoid valve 402 is not required, and the controller directly controls the operation of the electric heating plate.

[0047] In a preferred embodiment, a first pressure sensor 108 is provided between the urea pump 105 and the external port 107 for detecting the pressure of the urea liquid; a second pressure sensor 207 is provided between the air pump 205 and the mixing chamber 301 for detecting the pressure of the compressed air; and a third pressure sensor 306 is provided between the second solenoid valve 304 and the nozzle 305 for detecting the pressure of the gas-liquid mixture.

[0048] By providing the first pressure sensor 108, the pressure within the urea pipeline 102 can be detected, and the pressure of the urea liquid can be monitored in real time. This facilitates timely adjustments and repairs when the pressure within the urea pipeline 102 becomes abnormal, thereby improving system reliability. By providing the second pressure sensor 207, the pressure within the air pipeline 202 can be detected, and the pressure of the compressed air can be monitored in real time. This facilitates timely adjustments and repairs when the pressure within the air pipeline 202 becomes abnormal, thereby further improving system reliability. By providing the third sensor 306, the pressure within the injection pipeline 302 can be detected, and the pressure of the gas-liquid mixture can be monitored in real time. This facilitates timely adjustments and repairs when the pressure within the injection pipeline 302 becomes abnormal, thereby further improving system reliability.

[0049] In a preferred embodiment, a liquid level sensor 110 is provided in the urea tank 101 .

[0050] By providing a liquid level sensor 110 in the urea tank 101 , the amount of urea in the urea tank 101 can be monitored in real time, so that urea can be replenished in time when the amount of urea is insufficient, thereby further improving the reliability of the system.

[0051] The urea supply and injection system with dual injection function provided in Example 1 of the present application includes four working modes, namely: standby mode, pressure build-up pre-injection mode, injection mode and pressure relief purge mode; the urea supply and injection system with dual injection function needs to go through these four modes in sequence in each working process.

[0052] Example 2

[0053] Please refer to Figure 2 The present application provides an injection system control method for controlling the urea supply injection system with dual injection function as described in Example 1, comprising the following steps:

[0054] S1: adjusting the two constant pressure reducing valves 303 respectively according to the pressure requirements of the ccSCR device and the SCR device in the injection pipeline 302;

[0055] S2: closing the first solenoid valve 106;

[0056] S3: turning on the urea supply device and the air assist device;

[0057] S4: When urea needs to be supplied to the ccSCR device, the second solenoid valve 304 on the injection line 302 connected to the ccSCR device is opened;

[0058] When urea needs to be supplied to the SCR device, the second solenoid valve 304 on the injection line 302 communicating with the SCR device is opened.

[0059] Specifically, the constant-pressure reducing valve 303 is used to adjust the pressure of the gas-liquid mixture transmitted from the mixing chamber 301. No matter how much the pressure of the gas-liquid mixture is when entering the constant-pressure reducing valve 303, the constant-pressure reducing valve 303 can reduce the pressure of the gas-liquid mixture to a certain set pressure. This is to meet the requirements of the ccSCR device and the SCR device for the injection pressure of the gas-liquid mixture.

[0060] Specifically, the method provided in this embodiment is used to switch the urea supply and injection system with dual injection function described in Example 1 to the injection mode.

[0061] Specifically, first, the constant pressure reducing valve 303 is adjusted according to the injection pressure requirements of the ccSCR device and the SCR device for the injection pipeline 302; then, the first solenoid valve 106 is closed and the urea pump 105 and the air pump 106 are turned on. Since the first solenoid valve 106 is closed, as the urea pump 105 works, the pressure in the urea pipeline 102 becomes increasingly greater, and the urea liquid is transmitted to the external port 107 and enters the mixing chamber 301 through the reversing valve 109. As the air pump 205 works, compressed air enters the mixing chamber 301, and the compressed air and urea liquid are mixed in the mixing chamber 301. After mixing in the mixing chamber 301, a high-pressure gas-liquid mixture is formed, and the gas-liquid mixture is transmitted from the outlet of the mixing chamber 301 to the two constant-pressure reducing valves 303 respectively. After the pressure is limited by the constant-pressure reducing valves 303, the gas-liquid mixture enters the injection pipe 302; finally, when urea needs to be provided to the ccSCR device, the second solenoid valve 304 on the injection pipe 302 connected to the ccSCR device is opened to provide urea to the ccSCR device; when the SCR device needs to provide urea, the second solenoid valve 304 on the injection pipe 302 connected to the SCR device is opened to provide urea to the SCR device.

[0062] The method provided in the embodiment can provide urea to the ccSCR device and the SCR device respectively through a urea supply device and an air assist device, while ensuring that when urea is provided to the ccSCR device and the SCR device respectively, the pressures of the gas-liquid mixtures in the two injection pipes 302 do not affect each other, thereby improving the urea supply efficiency.

[0063] Example 3

[0064] This embodiment provides a control method for switching the urea supply and injection system with dual injection function described in Example 1 to the standby mode, comprising the following steps:

[0065] S1, controlling the first solenoid valve 106 to close;

[0066] S2. Control the urea pump 105 and the air pump 205 to be turned off.

[0067] Specifically, when the system is placed in the standby mode, since the first one-way valve 104 and the urea pump 105 are both in a closed state and the second port is above the urea liquid level, the urea liquid cannot flow from the first port through the urea pipeline to the second port, and also cannot enter the urea pipeline 102 from the second port, thereby preventing the urea liquid from entering the urea pipeline 102 and crystallizing in the urea pipeline 102, causing pipeline blockage.

[0068] Example 4

[0069] This embodiment provides a control method for controlling the urea supply and injection system with dual injection functions described in Example 1 to switch to the pressure-building pre-injection mode, including the following steps:

[0070] S1: Control the reversing valve 109 to conduct from the mixing chamber 301 to the external port 107;

[0071] S2: Control the first solenoid valve 106 to open;

[0072] S3: Control the urea pump 105 to be turned on and control the air pump 205 to be turned off.

[0073] Specifically, when the system is placed in the pressure-building pre-injection mode, the urea pump 105 pumps urea liquid from the urea tank 101 into the urea pipeline 102 through the first port. Since the reversing valve 109 is connected from the mixing chamber 301 to the external port 107, and the first solenoid valve 106 is opened, the urea liquid entering the urea pipeline 102 flows back into the urea tank 101 through the second port. Under normal circumstances, the system is placed in the pressure-building pre-injection stage for generally 30 seconds, the purpose of which is to fill the urea pipeline 102 with urea liquid to facilitate subsequent injection of urea liquid, that is, to prepare for the subsequent placement of the system in the injection mode.

[0074] Example 5

[0075] This embodiment provides a control method for controlling the urea supply and injection system with dual injection function described in the embodiment to switch to the pressure relief and purge mode, including the following steps:

[0076] S1: Control the reversing valve 109 to conduct from the mixing chamber 301 to the external port 107:

[0077] S2: Control the first solenoid valve 106 and the second solenoid valve 304 to open;

[0078] S3: Control the urea pump 105 to be turned off and control the air pump 205 to be turned on.

[0079] Specifically, when the system is placed in the pressure relief purge mode, since the reversing valve 109 is connected from the mixing chamber 301 to the external port 107, the first solenoid valve 106 and the second solenoid valve 304 are opened, the urea pump 105 is closed and the air pump 205 is opened, so that the compressed air is respectively delivered to the urea pipe 102 and the injection pipe 302 through the mixing chamber 301; in the urea pipe 102, since the first one-way valve 104 is provided, the compressed air can only be discharged from the urea pipe 102. The second port enters the urea tank 101, thereby assisting the residual urea in the urea tank 101 to be discharged from the urea tank 101, ensuring the separation of the urea pipe 102, and preventing the surface urea from crystallizing in the urea pipe 102 and causing blockage of the urea pipe 102; in the injection pipe 302, compressed air assists the urea in the injection pipe 302 to be discharged from the injection pipe 302, ensuring the cleanliness of the injection pipe 302, and preventing the urea from crystallizing in the injection pipe 302 and causing blockage of the injection pipe 302.

[0080] In a preferred embodiment, the urea pump 105 is a one-way pump or a two-way pump.

[0081] Specifically, when the urea pump 105 is a unidirectional pump, it can only extract urea liquid during the injection phase and flow the urea liquid from the first port to the second port. When the urea pump 105 is a bidirectional pump, in addition to extracting urea liquid during the injection phase, the urea pump 105 can also be reversely opened during the pressure relief and purge phase, while the first solenoid valve 106 is closed. The pressure provided by the urea pump 105 is used to suck back the urea at the nozzle 305 and flow back. After passing through the reversing valve 107 and the urea pipeline 102, the urea enters the urea tank 101 to further clean the pipeline.

[0082] The above description is merely a preferred embodiment of the present application and an illustration of the technical principles employed. Those skilled in the art should understand that the scope of the invention herein is not limited to the technical solutions formed by the specific combination of the above-mentioned technical features, but also encompasses other technical solutions formed by any combination of the above-mentioned technical features or their equivalents without departing from the inventive concept. For example, a technical solution formed by replacing the above-mentioned features with (but not limited to) technical features having similar functions disclosed in this application.

Claims

1. A urea supply and injection system with dual injection function, characterized in that: The invention comprises a urea supply device, an air assist device and a mixing chamber (301), wherein the urea supply device and the air assist device are respectively connected to the inlet end of the mixing chamber (301); the urea supply device is used to provide urea liquid into the mixing chamber (301); and the air assist device is used to provide compressed air into the mixing chamber (301) to assist in spraying the urea liquid. The outlet end of the mixing chamber (301) is connected to two injection pipelines (302), and the two injection pipelines (302) are arranged in parallel and are respectively connected to a tightly coupled selective catalytic reduction device and a selective catalytic reduction device; a constant pressure reducing valve (303) and a second solenoid valve (304) are sequentially arranged on the injection pipeline (302) from an end close to the mixing chamber (301) to an end away from the mixing chamber (301); the constant pressure reducing valve (303) is used to control the pressure in the injection pipeline (302); The urea supply device comprises a urea tank (101) and a urea pipeline (102), wherein the urea tank (101) contains urea liquid; the urea pipeline (102) comprises a first port and a second port, both of which are connected to the urea tank (101); a liquid inlet filter (103), a first one-way valve (104), a urea pump (105), and a first solenoid valve (106) are sequentially arranged between the first port and the second port; the urea pipeline (102) is further provided with an external port (107) between the urea pump (105) and the first solenoid valve (106), wherein the external port (107) is connected to the mixing chamber (301); a reversing valve (109) is arranged between the external port (107) and the mixing chamber (301); The air assist device comprises a compressed air tank (201) and an air pipeline (202), one end of the air pipeline (202) being connected to the compressed air tank (201), and the other end being connected to the mixing chamber (301); the air pipeline (202) is sequentially connected to an air filter (203), a second one-way valve (204), an air pump (205), and a throttle valve (206).

2. The urea supply and injection system with dual injection function according to claim 1, characterized in that: The first port is below the urea liquid level, and the second port is above the urea liquid level.

3. The urea supply and injection system with dual injection function according to claim 1, characterized in that: The system further comprises a urea heating device, the urea heating device comprising a circulating water pipeline (401) and a third solenoid valve (402), the water inlet end of the circulating water pipeline (401) being in communication with the water outlet pipe of the engine cooling circulating water, and the water outlet end of the circulating water pipeline (401) being in communication with the water inlet pipe of the engine cooling circulating water; the third solenoid valve (402) being arranged at the water inlet end of the circulating water pipeline (401); the circulating water pipeline (401) comprising a first heating part, a second heating part and a third heating part connected in sequence, the first heating part and the third heating part being respectively used to heat the two injection pipelines (302), and the second heating part being used to heat the urea tank (101).

4. The urea supply and injection system with dual injection function according to claim 3, characterized in that: The first heating part and the third heating part are spirally wound around the two injection pipelines (302) respectively.

5. The urea supply and injection system with dual injection function according to claim 4, characterized in that: The second heating portion extends into the urea tank (101) and is densely distributed in a spiral shape in the urea tank (101).

6. The urea supply and injection system with dual injection function according to claim 5, characterized in that: A first pressure sensor (108) is provided between the urea pump (105) and the external interface (107) for detecting the pressure of the urea liquid; a second pressure sensor (207) is provided between the air pump (205) and the mixing chamber (301) for detecting the pressure of the compressed air; and a third pressure sensor (306) is provided between the second solenoid valve (304) and the nozzle (305) for detecting the pressure of the gas-liquid mixture.

7. The urea supply and injection system with dual injection function according to claim 6, characterized in that: A liquid level sensor (110) is provided in the urea tank (101).

8. A method for controlling an injection system, for controlling the urea supply injection system with dual injection function according to any one of claims 1 to 7, characterized in that: The steps include: According to the pressure requirements of the close-coupled selective catalytic reduction device and the selective catalytic reduction device on the injection pipeline (302), respectively adjusting the two constant pressure reducing valves (303); Close the first solenoid valve (106); turning on the urea supply device and the air assist device; When urea needs to be supplied to the close-coupled selective catalytic reduction device, a second solenoid valve (304) on an injection line (302) communicating with the close-coupled selective catalytic reduction device is opened; When urea needs to be supplied to the selective catalytic reduction device, a second solenoid valve (304) on an injection line (302) communicating with the selective catalytic reduction device is opened.

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