Cooling method for postprocessor nozzle of diesel engine

Abstract

The invention discloses a cooling method for a diesel engine postprocessor nozzle, and relates to the technical field of urea nozzle cooling, and the cooling method comprises the following steps: stopping an engine, immediately suspending the engine from inputting cooling liquid into an adapter tube head A, and not flowing back through the interior of an adapter tube head B; starting the pipeline pump to enable the pipeline pump to pump liquid from the pump water inlet pipe to the pump water outlet pipe; according to the technical scheme, one end of a cooling pipe connector B and one end of a cooling pipe connector A are connected with an adapter pipe connector B with a flow dividing pipe B and an adapter pipe connector A with a flow dividing pipe A in a rotating mode, and a pipeline pump is connected between the flow dividing pipe A and the flow dividing pipe B through a pipeline, so that under the condition that the pipeline pump works actively, the flow dividing pipe A and the flow dividing pipe B are connected through a pipeline; a relatively closed loop is formed between the pipeline pump and the urea pipe cooling pipeline, so that engine cooling liquid accumulated in the loop circularly flows in a small range in a short time, and the urea pipe can be cooled continuously under the condition that an engine stops.

Description

Technical Field

[0001] The invention relates to the technical field of urea nozzle cooling, in particular to a cooling method for a diesel engine post-processor nozzle. Background Art

[0002] The cooling principle of the diesel generator post-processor urea nozzle is achieved by using the engine's cooling system. The urea nozzle works in a high temperature and high pressure environment, so it needs to be cooled with coolant. Specifically, there are two coolant joints inside the urea nozzle with an outer diameter of 10mm. These joints are connected to the engine's cooling system, and the nozzle is cooled by coolant to ensure the normal operation of the nozzle.

[0003] Urea nozzle is an important part of diesel vehicle SCR system. Its main function is to spray bonded urea liquid into the vehicle exhaust treatment system, converting nitrogen oxides (NOx) in the exhaust gas into harmless nitrogen and water vapor through chemical reactions, thereby significantly reducing diesel vehicle exhaust emissions. Urea nozzle uses a high-pressure system to spray urea liquid into the catalyst. After heating inside the nozzle, the urea liquid turns into ammonia, and then catalytically reacts with NOx in the exhaust gas on the catalyst to purify the exhaust gas.

[0004] The structure of the urea nozzle includes hydraulic interface, electrical interface, urea injection valve, nozzle body, heating guard plate and sealing disk. The hydraulic interface has two coolant connectors and one urea liquid connector, and the electrical interface has a two-pin plug connected to the ECU. The urea injection valve executes the injection command of the ECU, and there are radially evenly distributed spray holes on the nozzle body and the heating guard plate for urea injection. Common faults include circuit faults and nozzle blockage. Circuit faults can be checked by checking the wiring harness and resistance value. If the nozzle is blocked, it needs to be cleaned or replaced.

[0005] Urea nozzle cooling is crucial in the process of spraying bonded urea liquid into the vehicle exhaust treatment system. Urea nozzle cooling failure is relatively common. The consequences of cooling failure mainly include that the urea solution cannot be sprayed normally due to urea nozzle cooling failure, which in turn affects the efficiency of the exhaust treatment system and causes excessive nitrogen oxide emissions; the urea nozzle cannot work normally, which in turn affects the combustion efficiency of the engine, resulting in a decrease in vehicle power and reduced acceleration performance; due to reduced combustion efficiency, fuel consumption will increase, resulting in increased fuel consumption and increased operating costs; cooling failure may cause the engine management system to detect anomalies, thereby lighting up the fault light; affecting the normal operation of the exhaust treatment system, causing system failure, and further affecting the vehicle's emission performance.

[0006] The reasons for the failure of urea nozzle cooling generally include nozzle blockage, damage to internal parts of the nozzle and failure of the urea solution supply system. During the actual use of the urea nozzle, the urea nozzle is kept cooled continuously, and after the engine is shut down, the urea nozzle cooling stops at the same time, which is easy to cause crystallization at the nozzle due to excessive nozzle temperature, and eventually the urea nozzle is blocked due to nozzle channel blockage, affecting the normal use of the urea nozzle. Summary of the invention

[0007] In order to overcome the shortcomings of the prior art, an embodiment of the present application provides a cooling method for a diesel engine afterprocessor nozzle, by connecting an adapter pipe joint B with a shunt pipe B and an adapter pipe joint A with a shunt pipe A at one end of a cooling pipe joint B and a cooling pipe joint A, and connecting a pipeline pump through a pipeline between the shunt pipe A and the shunt pipe B. A one-way valve is provided between the shunt pipe A and the pump inlet pipe on the pipeline pump, and a one-way valve is provided between the adapter pipe joint A and one end of the adapter pipe joint B and the engine cooling pipeline. When the pipeline pump is actively working, a relatively closed loop can be formed between the pipeline pump and the urea pipe cooling pipeline. In a short time, the engine coolant accumulated in the loop can circulate in a small range, so that the urea pipe can still be cooled for a period of time when the engine is stopped, thereby avoiding crystallization caused by excessive temperature of the pipeline pump, which eventually causes blockage.

[0008] The technical solution adopted by the embodiment of the present application to solve the technical problem is:

[0009] A method for cooling a diesel engine post-processor nozzle comprises the following steps: the engine coolant is input into the interior of an adapter pipe A through an engine cooling pipeline, flows into a urea pipe cooling pipeline through the adapter pipe A and the cooling pipe joint A, and flows out from the cooling pipe joint B to the interior of the adapter pipe B;

[0010] Step 2: Stop the engine, and then stop the engine from supplying coolant to the inside of adapter A, and stop the coolant from flowing back through the inside of adapter B;

[0011] Step 3: Start the pipeline pump to pump liquid from the pump inlet pipe to the pump outlet pipe. The coolant flows into the inside of the pump inlet pipe through the shunt pipe A on the adapter A, and flows into the inside of the shunt pipe B through the pump outlet pipe.

[0012] Step 4: The engine coolant flows from the shunt pipe A to the inside of the shunt pipe B through the pipeline pump, and flows to the inside of the cooling pipe joint A through the cooling pipe joint B and the urea pipe cooling pipe;

[0013] Among them, in the step one, the engine coolant is diverted from the inside of the adapter pipe A to the inside of the diverter pipe A, and is pumped out to the inside of the diverter pipe B by the pipeline pump, and flows along with the engine coolant flowing out from the cooling pipe joint B to the inside of the adapter pipe joint B.

[0014] Preferably, in the step 1, the adapter pipe A is arranged at one end of the cooling pipe joint A, the adapter pipe B is arranged at one end of the cooling pipe joint B, the bottoms of the cooling pipe joint B and the cooling pipe joint A are jointly provided with a nozzle base, the middle of the nozzle base is assembled and connected with a urea liquid inlet pipe, and the outsides of the cooling pipe joint B and the cooling pipe joint A are jointly equipped with a heat insulation sheet;

[0015] The middle part of the adapter pipe A is processed with a shunt pipe A which is perpendicular to the adapter pipe, and the middle part of the adapter pipe B is processed with a shunt pipe B which is perpendicular to the adapter pipe;

[0016] A buckle frame is provided between the adapter pipe joint B and the cooling pipe joint B, and between the adapter pipe joint A and the cooling pipe joint A, and one side of the buckle frame is assembled with a connection limit strip;

[0017] A urea pipe cooling pipeline is assembled and connected between the cooling pipe joint B and one end of the cooling pipe joint A. The urea pipe cooling pipeline bypasses the outside of one end of the urea inlet pipe and reduces the temperature of the urea pipe when urea flows through the inside of the urea inlet pipe.

[0018] Preferably, in step 3, the pump water inlet pipe is processed to the top of the pipeline pump, and the pump water outlet pipe is processed to one side of the pipeline pump;

[0019] Among them, one end of the diverter pipe A and one end of the pump water inlet pipe are connected by a hose to form a line IIa-IIb, one end of the pump water outlet pipe and one end of the diverter pipe B are connected by a hose to form a line IIIa-IIIb, and the engine coolant enters the interior of the cooling pipe joint A through the adapter pipe connector A, and flows back from the interior of the cooling pipe joint B through the adapter pipe connector B. The line is Ia-Ib. During the flow of the engine coolant in the line Ia-Ib, it is diverted through the line IIa-IIb and the line IIIa-IIIb to support the pipeline pump to form a coolant circulation loop in a local area.

[0020] Preferably, a one-way valve is also assembled on the hose connected between one end of the diversion pipe A and one end of the pump water inlet pipe to support the engine coolant to flow only from the inside of the adapter connector A to the inside of the adapter connector B.

[0021] Preferably, a one-way valve is also assembled on the hose connected between one end of the diversion pipe A and one end of the pump water inlet pipe to support the engine coolant to flow only from the inside of the adapter connector A to the inside of the adapter connector B.

[0022] Preferably, the pipeline pump controls the coolant to flow through the shunt pipe A to the shunt pipe B, and with the help of the adapter joint A and the engine cooling pipeline, and the one-way valve between the adapter joint B and the engine cooling pipeline, a closed loop is formed between the urea pipe cooling pipeline, the cooling pipe joint B, the cooling pipe joint A, the pipeline pump, the pump outlet pipe and the shunt pipe B.

[0023] Preferably, the engine shutdown state and the pipeline pump start state in step 2 and step 3 are set by PLC programming. When the engine is stopped, the pipeline pump is started immediately, and the working time of the pipeline pump is set to two minutes by the PLC.

[0024] Preferably, in the closed loop formed between the urea pipe cooling pipeline, cooling pipe joint B, cooling pipe joint A, pipeline pump, pump outlet pipe and diversion pipe B, when the engine is stopped, the pipeline pump controls the engine coolant accumulated in the closed loop to flow in the opposite direction of the local liquid flow of line Ⅰa-Ⅰb.

[0025] In summary, the present invention includes at least one of the following beneficial technical effects:

[0026] In the present solution, an adapter pipe joint B with a shunt pipe B and an adapter pipe joint A with a shunt pipe A are connected at one end of the cooling pipe joint B and the cooling pipe joint A, and a pipeline pump is connected between the shunt pipe A and the shunt pipe B through a pipeline. A one-way valve is provided between the shunt pipe A and the pump water inlet pipe on the pipeline pump, and a one-way valve is provided between the adapter pipe joint A and one end of the adapter pipe joint B and the engine cooling pipeline. When the pipeline pump is actively working, a relatively closed loop can be formed between the pipeline pump and the urea pipe cooling pipeline. In a short time, the engine coolant accumulated in the loop can circulate in a small range, so that the urea pipe can be cooled for a period of time when the engine is stopped. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is one of the overall structural schematic diagrams of the present invention;

[0028] Figure 2 This is the second schematic diagram of the overall structure of the present invention;

[0029] Figure 3 It is a schematic diagram of the cooling process of the urea liquid inlet pipe of the present invention;

[0030] Figure 4 It is a schematic diagram of the system for cooling the urea liquid inlet pipe of the present invention.

[0031] Figure numerals: 1. pipeline pump; 2. pump water inlet pipe; 3. pump water outlet pipe; 4. adapter pipe A; 5. shunt pipe A; 6. nozzle base; 7. cooling pipe joint A; 8. limit strip; 9. buckle bracket; 10. thermal insulation sheet; 11. adapter pipe B; 12. urea liquid inlet pipe; 13. shunt pipe B; 14. cooling pipe joint B. DETAILED DESCRIPTION

[0032] Embodiment 1:

[0033] A method for cooling a nozzle of a diesel engine aftertreatment device, such as Figure 1-Figure 4 As shown, it includes S1: the engine coolant is input into the interior of the adapter pipe A4 through the engine cooling pipeline, flows into the urea pipe cooling pipeline through the adapter pipe A4 and the cooling pipe joint A7, and flows out from the cooling pipe joint B14 to the interior of the adapter pipe joint B11;

[0034] At the same time, the engine coolant is diverted from the inside of the adapter pipe A4 to the inside of the diverter pipe A5, and is pumped out from the pipeline pump 1 to the inside of the diverter pipe B13, following the engine coolant flowing out from the cooling pipe joint B14 to the inside of the adapter pipe joint B11;

[0035] Among them, under normal conditions, the engine coolant is input to the inside of the adapter connector A4 through the engine cooling pipeline, flows into the urea pipe cooling pipeline from the adapter connector A4 and the cooling pipe joint A7, and flows out from the cooling pipe joint B14 to the inside of the adapter connector B11, carrying the engine coolant in the inside of the adapter connector A4 to the inside of the diverter pipe A5, and is pumped out by the pipeline pump 1 to the inside of the diverter pipe B13, and follows the engine coolant flowing out from the cooling pipe joint B14 to the inside of the adapter connector B11, without affecting the engine working state, the coolant circulates in a fixed flow direction;

[0036] Secondly, during the engine shutdown process, the pipeline pump 1 provides power for the local coolant circulation flow, which can reduce energy loss and ensure that the urea pipe continues to be cooled for a period of time;

[0037] like Figure 1 and Figure 2 As shown, in step 1, the adapter pipe A4 is arranged at one end of the cooling pipe joint A7, the adapter pipe B11 is arranged at one end of the cooling pipe joint B14, the bottom of the cooling pipe joint B14 and the cooling pipe joint A7 are jointly provided with a nozzle base 6, the middle of the nozzle base 6 is assembled and connected with a urea liquid inlet pipe 12, and the outside of the cooling pipe joint B14 and the cooling pipe joint A7 are jointly equipped with a heat insulation sheet 10;

[0038] The middle part of the adapter A4 is processed with a shunt pipe A5 which is perpendicular to the adapter, and the middle part of the adapter B11 is processed with a shunt pipe B13 which is perpendicular to the adapter;

[0039] A buckle frame 9 is provided between the adapter pipe joint B11 and the cooling pipe joint B14, and between the adapter pipe joint A4 and the cooling pipe joint A7. One side of the buckle frame 9 is assembled and connected with a limit strip 8.

[0040] A urea pipe cooling pipeline is assembled and connected between the cooling pipe joint B14 and one end of the cooling pipe joint A7. The urea pipe cooling pipeline bypasses the outside of one end of the urea liquid inlet pipe 12. When urea flows through the inside of the urea liquid inlet pipe 12, the temperature of the urea pipe is reduced, thereby reducing the temperature of the urea.

[0041] S2: Stop the engine, and then stop the coolant supply to the inside of the adapter A4, and stop the coolant return through the inside of the adapter B11;

[0042] S3: Start the pipeline pump 1, so that the pipeline pump 1 draws liquid from the pump inlet pipe 2 to the pump outlet pipe 3, and the coolant flows into the inside of the pump inlet pipe 2 through the shunt pipe A5 on the adapter A4 and the one-way valve between the pump inlet pipe 2 and the shunt pipe A5, and flows into the inside of the shunt pipe B13 through the pump outlet pipe 3;

[0043] Among them, the engine shutdown state and the start state of pipeline pump 1 are set by PLC programming. When the engine is stopped, pipeline pump 1 starts immediately, and the working time of pipeline pump 1 is set by PLC to two minutes;

[0044] Secondly, by connecting a hose between one end of the shunt pipe A5 and one end of the pump water inlet pipe 2, and one end of the pump water outlet pipe 3 and the shunt pipe B13, and a one-way valve is also assembled and connected to the hose connected between one end of the shunt pipe A5 and one end of the pump water inlet pipe 2, the engine coolant is supported to flow only from the inside of the adapter A4 to the inside of the adapter B11, maintaining a one-way flow state;

[0045] At the same time, two one-way valves are provided, which are respectively installed between the adapter A4 and the engine cooling pipeline, and between the adapter B11 and the engine cooling pipeline. When the pipeline pump 1 is working, a closed loop of circulating flow is formed between the urea pipe cooling pipeline and the pipeline pump 1, and the engine coolant is supported to flow only to the adapter A4, and refluxed from the inside of the adapter B11, so as to ensure that the engine coolant in the closed loop of circulating flow formed between the urea pipe cooling pipeline and the pipeline pump 1 is sufficient;

[0046] Furthermore, in step 3, the pump inlet pipe 2 is processed to the top of the pipeline pump 1, and the pump outlet pipe 3 is processed to one side of the pipeline pump 1. By using a hose to connect one end of the shunt pipe A5 and one end of the pump inlet pipe 2, a line IIa-IIb is formed, and between one end of the pump outlet pipe 3 and one end of the shunt pipe B13, a line IIIa-IIIb is formed. At the same time, the engine coolant enters the interior of the cooling pipe joint A7 through the adapter pipe A4, and the line of the reflux from the interior of the cooling pipe joint B14 through the adapter pipe B11 is Ia-Ib. When the engine coolant flows in the line Ia-Ib, it can be shunted through the line IIa-IIb and the line IIIa-IIIb to support 1 to form a coolant circulation loop in a local range;

[0047] When the engine is stopped, 1 can be used to control the circulation of the remaining coolant in the line IIa-IIb, the line IIIa-IIIb, the cooling pipe joint A7, the cooling pipe joint B14 and the urea pipe cooling line;

[0048] In this state, a closed loop is formed between the urea pipe cooling line, the cooling pipe joint B14, the cooling pipe joint A7, the pipeline pump 1, the pump outlet pipe 3 and the diverter pipe B13. When the engine is stopped, the pipeline pump 1 controls the engine coolant accumulated in the closed loop to flow in the opposite direction of the local liquid flow of line Ⅰa-Ⅰb;

[0049] S4: The engine coolant flows from the shunt pipe A5 to the inside of the shunt pipe B13 through the pipeline pump 1, so that the engine coolant flows to the inside of the cooling pipe joint A7 through the cooling pipe joint B14 and the urea pipe cooling pipe;

[0050] Among them, the pipeline pump 1 controls the coolant to flow to the shunt pipe B13 through the shunt pipe A5. With the help of the adapter joint A4 and the engine cooling pipeline, and the one-way valve between the adapter joint B11 and the engine cooling pipeline, a closed loop can be formed between the urea pipe cooling pipeline, the cooling pipe joint B14, the cooling pipe joint A7, the pipeline pump 1, the pump outlet pipe 3 and the shunt pipe B13 to reduce the pressure in the local coolant circulation process controlled by the pipeline pump 1.

[0051] The present invention discloses a cooling method for a diesel engine after-processor nozzle. The method comprises the following steps: connecting a connecting pipe joint B11 with a shunt pipe B13 and a connecting pipe joint A4 with a shunt pipe A5 at one end of a cooling pipe joint B14 and a cooling pipe joint A7, and connecting a pipeline pump 1 through a pipeline between the shunt pipe A5 and the shunt pipe B13. A one-way valve is arranged between the shunt pipe A5 and a pump water inlet pipe 2 on the pipeline pump 1, and a one-way valve is arranged between one end of the connecting pipe joint A4 and the connecting pipe joint B11 and the engine cooling pipeline. When the pump 1 is actively working, a relatively closed loop is formed between the pipeline pump 1 and the urea pipe cooling pipeline (a closed loop formed between the urea pipe cooling pipeline, the cooling pipe joint B14, the cooling pipe joint A7, the pipeline pump 1, the pump outlet pipe 3 and the diversion pipe B13). In a short time, the engine coolant accumulated in the loop circulates in a small range, so that the urea pipe can be cooled for a period of time when the engine is stopped, so as to avoid crystallization caused by excessive temperature of the pipeline pump 1, which eventually causes blockage.

[0052] Finally, it should be noted that: Obviously, the above embodiments are only examples for clearly explaining the present invention, and are not intended to limit the implementation methods. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from this are still within the scope of protection of the present invention.

Claims

1. A method for cooling a diesel engine aftertreatment nozzle, characterized in that: include: Step 1: The engine coolant is input into the interior of the adapter pipe A (4) through the engine cooling pipeline, flows into the urea pipe cooling pipeline through the adapter pipe A (4) and the cooling pipe joint A (7), and flows out from the cooling pipe joint B (14) to the interior of the adapter pipe joint B (11); Step 2: Stop the engine, and then stop the engine from supplying coolant to the interior of the adapter A (4), and stop the engine from returning coolant through the interior of the adapter B (11); Step 3: Start the pipeline pump (1) so that the pipeline pump (1) draws liquid from the pump inlet pipe (2) to the pump outlet pipe (3), and the coolant flows into the inside of the pump inlet pipe (2) through the diverter pipe A (5) on the adapter pipe A (4), and flows into the inside of the diverter pipe B (13) through the pump outlet pipe (3); Step 4: The engine coolant flows from the shunt pipe A (5) through the pipeline pump (1) to the inside of the shunt pipe B (13), and flows to the inside of the cooling pipe joint A (7) through the cooling pipe joint B (14) and the urea pipe cooling pipe; In the step 1, the engine coolant is diverted from the inside of the adapter pipe A (4) to the inside of the diverter pipe A (5), and is pumped out from the pipeline pump (1) to the inside of the diverter pipe B (13), and flows along with the engine coolant flowing out from the cooling pipe joint B (14) to the inside of the adapter pipe joint B (11).

2. A method for cooling a diesel engine post-processor nozzle as claimed in claim 1, characterized in that: In the step 1, the adapter pipe joint A (4) is arranged at one end of the cooling pipe joint A (7), the adapter pipe joint B (11) is arranged at one end of the cooling pipe joint B (14), the bottom of the cooling pipe joint B (14) and the cooling pipe joint A (7) are jointly provided with a nozzle base (6), the middle of the nozzle base (6) is assembled and connected with a urea liquid inlet pipe (12), and the outside of the cooling pipe joint B (14) and the cooling pipe joint A (7) are jointly provided with a heat insulation sheet (10); The middle part of the adapter pipe A (4) is processed with a shunt pipe A (5) which is perpendicular to the adapter pipe A (4), and the middle part of the adapter pipe B (11) is processed with a shunt pipe B (13) which is perpendicular to the adapter pipe B (11); A buckle frame (9) is provided between the adapter pipe joint B (11) and the cooling pipe joint B (14), and between the adapter pipe joint A (4) and the cooling pipe joint A (7), and a mounting connection limit strip (8) is provided on one side of the buckle frame (9); A urea pipe cooling pipeline is assembled and connected between the cooling pipe joint B (14) and one end of the cooling pipe joint A (7). The urea pipe cooling pipeline bypasses the outside of one end of the urea liquid inlet pipe (12) and reduces the temperature of the urea pipe when urea flows through the inside of the urea liquid inlet pipe (12).

3. A method for cooling a diesel engine post-processor nozzle as claimed in claim 2, characterized in that: In the step 3, the pump water inlet pipe (2) is processed to the top of the pipeline pump (1), and the pump water outlet pipe (3) is processed to one side of the pipeline pump (1); One end of the diverter pipe A (5) and one end of the pump water inlet pipe (2) are connected by a hose to form a line IIa-IIb, one end of the pump water outlet pipe (3) and one end of the diverter pipe B (13) are connected by a hose to form a line IIIa-IIIb, and the engine coolant enters the interior of the cooling pipe joint A (7) through the adapter pipe connector A (4) and flows back from the interior of the cooling pipe joint B (14) through the adapter pipe connector B (11) to form a line Ia-Ib. During the process of the engine coolant flowing in the line Ia-Ib, it is diverted through the line IIa-IIb and the line IIIa-IIIb to support the pipeline pump (1) to form a coolant circulation loop in a local area.

4. A method for cooling a diesel engine post-processor nozzle as claimed in claim 3, characterized in that: A one-way valve is also assembled and connected to the hose connected between one end of the diverter pipe A (5) and one end of the pump water inlet pipe (2), so as to support the engine coolant to flow only from the inside of the adapter pipe A (4) to the inside of the adapter pipe B (11).

5. A method for cooling a diesel engine post-processor nozzle as claimed in claim 4, characterized in that: The one-way valve also includes two ones, which are respectively assembled between the adapter pipe A (4) and the engine cooling pipeline, and between the adapter pipe B (11) and the engine cooling pipeline, so as to support the engine coolant to flow only to the adapter pipe A (4) and to flow back from the inside of the adapter pipe B (11).

6. A method for cooling a diesel engine post-processor nozzle as claimed in claim 5, characterized in that: The pipeline pump (1) controls the coolant to flow through the shunt pipe A (5) to the shunt pipe B (13), and by means of a one-way valve between the adapter pipe joint A (4) and the engine cooling pipe, and between the adapter pipe joint B (11) and the engine cooling pipe, a closed loop is formed between the urea pipe cooling pipe, the cooling pipe joint B (14), the cooling pipe joint A (7), the pipeline pump (1), the pump outlet pipe (3) and the shunt pipe B (13).

7. A method for cooling a diesel engine post-processor nozzle as claimed in claim 1, characterized in that: The engine shutdown state and the start state of the pipeline pump (1) in step 2 and step 3 are set by PLC programming. When the engine is stopped, the pipeline pump (1) is started immediately. The working time of the pipeline pump (1) is set to two minutes by the PLC.

8. A method for cooling a diesel engine post-processor nozzle as claimed in claim 4, characterized in that: A closed loop is formed between the urea pipe cooling pipe, the cooling pipe joint B (14), the cooling pipe joint A (7), the pipe pump (1), the pump outlet pipe (3) and the diverter pipe B (13). When the engine is stopped, the pipe pump (1) controls the engine coolant accumulated in the closed loop to flow in the opposite direction of the local liquid flow of the line Ia-Ib.

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