Liquid reducing agent metering injection device

Abstract

The liquid reducing agent metering injection device provided by the present invention can achieve the urea aqueous solution injection pressure stabilization effect by using the filtering energy storage device to intermittently supplement the pressure through the delivery pump. Compared with the prior art that uses a throttle valve and a pressure valve to continuously overflow and return the liquid through the delivery pump to achieve the urea aqueous solution injection pressure stabilization effect, the urea metering injection device has a simple and reliable structure, which not only increases the service life (no need to operate under heavy load) and reliability of the delivery pump, but also greatly reduces the operating cost of the device. In addition, the switching between the injection and evacuation stages of the device does not require a complex two-position four-way reversing valve, which greatly reduces the complexity of the device structure, increases its reliability, and reduces its risk of freezing and cracking.

Description

Technical Field

[0001] The invention belongs to the field of diesel engine exhaust aftertreatment, and relates to a liquid reducing agent metering injection device, in particular to a urea metering injection device. Background Art

[0002] The metering injection device of liquid reducing agent (such as urea aqueous solution) is an important device in the selective catalytic reduction system (Selective Catalytic Reduction, SCR) of diesel engines. Its working principle is as follows: the delivery pump in the device sucks the urea aqueous solution from the urea storage tank, forms a urea aqueous solution with a stable pressure through the pressure stabilizing unit, and then injects the urea aqueous solution into the catalytic muffler in a quantitative manner in a fine mist through the dosing module. In this way, the fine mist urea aqueous solution first undergoes hydrolysis and pyrolysis reactions at high temperature to generate ammonia, and then the ammonia undergoes oxidation-reduction reactions with nitrogen oxides in the exhaust gas discharged by the diesel engine in the catalytic muffler to regenerate nitrogen and water, thereby achieving the purpose of reducing the nitrogen oxide emissions of the diesel engine.

[0003] like Figure 1 , which is a urea aqueous solution metering injection device in the prior art, comprises a urea aqueous solution storage tank 1, a liquid suction pipe A2, a filter 3, a liquid suction pipe B4, a two-position four-way reversing valve 5, a liquid suction pipe C6, a delivery pump 7 (with urea aqueous solution supply and withdrawal functions), a main injection pipe 8, an injection pipe A9, a two-position four-way reversing valve 5, an injection pipe B10, a dosing module 11, a liquid return pipe A12, a pressure sensor 13, a pressure valve 14, a liquid return pipe B15, a throttle valve 16, a liquid return pipe C17, a withdrawal pipe A18, a withdrawal pipe B19, a withdrawal pipe C20 and a withdrawal pipe D21.

[0004] Here’s how it works:

[0005] Metered injection process: After the system is powered on, the delivery pump 7 starts to work, and the urea aqueous solution is extracted from its storage tank 1 through the suction pipe A2, and enters the delivery pump 7 through the filter 3, suction pipe B4, two-position four-way reversing valve 5, and suction pipe C6 in the supply branch, and then flows out to the main injection pipe 8 in the injection branch and is divided into two paths: one path (injection branch) is sequentially through the injection pipe A9, the two-position four-way reversing valve 5, and the injection pipe B10 to reach the dosing module 11; the other path (overflow branch) is sequentially through the return pipe A12, the pressure sensor 13, the pressure valve 14, the return pipe B15, the throttle valve 16, and the return pipe C17, and flows back to the storage tank 1.

[0006] Evacuation process: firstly, power on the two-position four-way reversing valve 5, then electronically control to open the nozzle in the metering module 11, and then electronically control to start the delivery pump 7. In this way, when the metering injection device is stopped, the urea aqueous solution remaining in the device is sequentially drawn from the metering module 11 in the injection branch, the injection pipe B10, the withdrawal pipe A18 in the withdrawal branch, the two-position four-way reversing valve 5, the withdrawal pipe 19, the suction pipe C6 in the supply branch, and then sucked into the delivery pump 7; then sequentially from the main injection pipe 8 in the supply branch, the injection pipe A9 in the injection branch, the withdrawal pipe B20 in the withdrawal branch, the two-position four-way reversing valve 5, the withdrawal pipe D21, and then through the suction pipe B4 in the supply branch, the filter 3, the suction pipe A2, and finally flows back to the storage tank 1.

[0007] During the metering injection process, the metering injection device uses the throttle valve 16 to continuously return liquid to the storage tank 1 (the purpose is to use the overflow of the urea aqueous solution to ensure the stability of the injection pressure of the dosing module 11, thereby ensuring the accuracy of the urea aqueous solution injection). The operating conditions of this metering injection device have very high requirements on the reliability and service life of the delivery pump 7, otherwise it is difficult to achieve the purpose of reducing the nitrogen oxide emissions of the diesel engine. In addition, when the metering injection device is evacuated, not only is the structure of the two-position four-way reversing valve 5 complex, but the connection pipeline of the withdrawal branch is also complex. At the same time, when the reversing valve and the withdrawal branch pipeline are evacuated, some urea aqueous solution often remains in the reversing valve and the withdrawal branch pipeline, causing it to be often frozen and cracked in winter and cannot be used. Summary of the invention

[0008] In order to solve the above problems, the purpose of the present invention is to provide a liquid reducing agent metering injection device with simple structure and high reliability, including a controller for controlling power supply to equipment in the device, a storage tank for storing liquid reducing agent, a supply branch for extracting the liquid reducing agent in the storage tank, a filtering energy storage device for filtering and storing the liquid reducing agent output by the supply branch, an injection branch for ejecting the liquid reducing agent filtered and stored in the filtering energy storage device, and a withdrawal branch for withdrawing the liquid reducing agent remaining in the supply branch, the filtering energy storage device and the injection branch. Further, the supply branch is composed of the storage box, the electrically driven delivery pump, the check valve and the filter energy storage device connected in sequence through a connecting pipe; the injection branch is composed of the filter energy storage device and the dosing module connected through a connecting pipe, and a pressure sensor is connected to the connecting pipe between the filter energy storage device and the dosing module; the withdrawal branch is composed of the filter energy storage device, the withdrawal pump module and the storage box connected in sequence through a connecting pipe, wherein the withdrawal pump module includes an electrically driven withdrawal pump and an electromagnetic on-off valve connected in series. Further, a filter is connected in series on the connecting pipe between the storage box and the electrically driven delivery pump in the supply branch. Further specific improvements to the above scheme are as follows:

[0009] The above three solutions are further improved as follows: the liquid reducing agent is a urea aqueous solution or AdBlue or AdBlue.

[0010] The latter two solutions are further improved as follows: the electrically driven delivery pump is driven by a motor or an electromagnet; the electrically driven withdrawal pump is driven by a motor or an electromagnet.

[0011] The above second solution is further improved as follows: the filtering energy storage device is a hollow rubber energy storage filtering device.

[0012] The above third solution is further improved as follows: the filtering energy storage device is a hollow rubber energy storage filtering device.

[0013] The above-mentioned second and third schemes are both further improved as follows:

[0014] 1) The hollow rubber energy storage filter device is mainly composed of a paper filter layer, a hollow rubber rod and a cap-shaped shell. The paper filter layer and the hollow rubber rod are sequentially embedded from the open end of the cap-shaped shell and fixed on the outside of the end through an end cap with a center hole; a liquid reducing agent inlet is set at the other end of the shell and passes through the paper filter layer directly to the hollow rubber rod, a liquid reducing agent injection outlet is set in the middle of the side wall of the shell, and a liquid reducing agent return outlet is set at the bottom of the side wall of the shell. Further, the liquid reducing agent is a urea aqueous solution or AdBlue or Add Blue.

[0015] 2) The electrically driven delivery pump is driven by a motor or an electromagnet; the electrically driven withdrawal pump (28) is driven by a motor or an electromagnet. Further, the liquid reducing agent is a urea aqueous solution or AdBlue or Add Blue.

[0016] 3) The hollow rubber energy storage filter device is mainly composed of a paper filter layer, a hollow rubber rod and a cap-shaped shell. The paper filter layer and the hollow rubber rod are sequentially embedded from the open end of the cap-shaped shell and fixed on the outside of the end through an end cover with a center hole; a liquid reducing agent inlet is set at the other end of the shell and passes through the paper filter layer directly to the hollow rubber rod, a liquid reducing agent injection outlet is set in the middle of the side wall of the shell, and a liquid reducing agent return outlet is set at the bottom of the side wall of the shell. Further, the electrically driven delivery pump is driven by a motor or an electromagnet; the electrically driven withdrawal pump (28) is driven by a motor or an electromagnet. Further, the liquid reducing agent is a urea aqueous solution or AdBlue or Add Blue.

[0017] The liquid reducing agent metering injection device provided by the present invention utilizes a filtering energy storage device to intermittently supplement the pressure through an electrically driven delivery pump to achieve the liquid reducing agent injection pressure stabilization effect. Compared with the prior art that uses a throttle valve and a pressure valve to continuously overflow and return the liquid through an electrically driven delivery pump to achieve the liquid reducing agent (urea aqueous solution) injection pressure stabilization effect, the metering injection device has a simple and reliable structure, which not only increases the service life (no need to operate under heavy load) and reliability of the electrically driven delivery pump, but also greatly reduces the operating cost of the device. In addition, the switching between the injection and evacuation stages of the device does not require a complex two-position four-way reversing valve, which greatly reduces the structural complexity of the device, increases its reliability, and reduces its risk of freezing and cracking. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the urea metering injection device system in the prior art.

[0019] Figure 2 It is a schematic diagram of the urea metering injection device system of the present invention.

[0020] Figure 3 for Figure 2 Schematic diagram of the cross-sectional structure of a filtering energy storage device in the system.

[0021] Figure 4 for Figure 3 Schematic diagram of the AA longitudinal section structure. DETAILED DESCRIPTION

[0022] The urea metering injection device provided by the present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0023] This embodiment provides a schematic diagram of a urea metering injection device system. Figure 2As shown, it includes a controller (not shown in the figure) for controlling power supply to the equipment in the device, a storage tank 1 for storing liquid reducing agent, a supply branch for extracting the liquid reducing agent in the storage tank 1, a filtering energy storage device 24 for filtering and storing the liquid reducing agent output by the supply branch, an injection branch for ejecting the filtered and stored liquid reducing agent in the filtering energy storage device 24, and a withdrawal branch for withdrawing the residual liquid reducing agent in the supply branch, the filtering energy storage device 24 and the injection branch; the supply branch consists of the storage tank 1, the suction pipe A2, the filter 3. The suction pipe B4, the electrically driven delivery pump 7 (with a supply function), the suction pipe C6, the check valve 22, the suction pipe D23 and the filtering energy storage device 24 are sequentially connected in series; the injection branch is sequentially connected in series with the filtering energy storage device 24, the injection pipe 9 and the dosing module 11, and a pressure sensor 13 is connected to the injection pipe 9; the withdrawal branch is sequentially connected in series with the filtering energy storage device 24, the withdrawal pipe 25, the withdrawal pump module 26, the return pipe 27 and the storage box 1, wherein the withdrawal pump module 26 includes an electrically driven withdrawal pump 28 (with a withdrawal function) and an electromagnetic on-off valve 29 connected in series. The check valve 22 is a valve that opens when the pressure of the urea aqueous solution in the suction pipe C6 reaches a certain value. The electrically driven delivery pump 7 is driven by a motor or an electromagnet; the electrically driven withdrawal pump 28 is driven by a motor or an electromagnet; the filtering energy storage device 24 is a hollow rubber energy storage filter device, such as Figure 3 and 4 The figure shows a hollow rubber energy storage filter device, which is mainly composed of a paper filter layer 01, a hollow rubber rod 02 and a cap-shaped shell 03. The paper filter layer 01 and the hollow rubber rod 02 are sequentially embedded from the open end of the cap-shaped shell 03 and fixed (through a thread) on the outside of the end through an end cover 04 with a center hole; a urea solution inlet 05 is arranged at the other end of the shell 03 and passes through the paper filter layer 01 directly to the hollow rubber rod 02, and is connected to the suction tube D23; a urea solution injection outlet 07 is arranged in the middle of the side wall of the shell 03, which is connected to the injection pipe 9; a urea solution return liquid outlet 06 is arranged at the bottom of the side wall of the shell 03 (arranged at the bottom of the side wall to facilitate the evacuation of the urea solution), and is connected to the return suction pipe 25.

[0024] The metering injection process includes pressure building stage, injection stage and evacuation stage. Its working principle is as follows:

[0025] 1. Pressure building stage:

[0026] The purpose is to inject the urea aqueous solution in the storage tank 1 into the filter energy storage device 24 in a short time and reach the injection pressure specified by the device; the specific process is as follows:

[0027] 1) After the device is powered on, its controller uses a temperature sensor (which monitors the ambient temperature of the device, Figure 4 (not shown) whether the device is to start a heating and thawing program;

[0028] 2) If the heating and thawing process is not required (if required, after the thawing process is completed), the electrically driven delivery pump 7 and the re-pump module 26 are directly started, and the urea aqueous solution is injected from the storage tank 1 into the filtering energy storage device 24 in sequence through the suction pipe A2, the filter 3, the suction pipe B4, the electrically driven delivery pump 7, the suction pipe C6, the check valve 22, and the suction pipe D23;

[0029] 3) After a period of time (about 30 seconds), the pump module 26 is stopped, and the dosing module 11 is started at the same time. The electrically driven delivery pump 7 then continues to work (for the purpose of exhausting the air in the filter energy storage device 24, the injection pipe 9 and the dosing module 11), and the dosing module 11 is turned off after a period of time;

[0030] 4) When the pressure sensor 13 connected to the injection pipe 9 detects that the pressure reaches the specified pressure value and stabilizes, the electrically driven delivery pump 7 stops working and the pressure building phase ends.

[0031] The flow path of the urea aqueous solution during the pressure building phase in the filter energy storage device 24 is as follows:

[0032] The pressurized urea aqueous solution flowing out of the check valve 22 flows through the suction pipe D23, first directly injects into the space between the paper filter layer 01 and the hollow rubber rod 02 through the urea solution inlet 05 of the filter energy storage device 24, then passes through the paper filter layer 01 and enters the space between the paper filter layer 01 and the outer shell 03, and finally flows out from the urea solution injection outlet 07 of the filter energy storage device 24 through the injection pipe 9.

[0033] 2. Spraying stage:

[0034] After the pressure building stage, when the device receives the injection control signal, the device controller intermittently opens the dosing module 11 at a certain pulse frequency, and the device performs metered injection of the urea aqueous solution; during the metered injection process, the pressure of the urea aqueous solution formed in the space formed by the check valve 22, the suction pipe D23, the filter energy storage device 24, and the injection pipe 9 during the pressure building stage will drop immediately; when the pressure drop of the urea aqueous solution in the space exceeds the prescribed allowable value, the electrically driven delivery pump 7 starts to replenish the urea solution so that the pressure of the urea aqueous solution in the space is maintained within the prescribed pressure value range, and the replenishment is stopped (to ensure the accuracy of the metered injection of the dosing module 11); when the pressure of the urea aqueous solution formed in the space formed by the check valve 22, the suction pipe D23, the filter energy storage device 24, and the injection pipe 9 during the metered injection process drops again and exceeds the prescribed allowable value, the electrically driven delivery pump 7 is started again to replenish the solution so that the pressure is maintained within the prescribed pressure value range; this cycle continues.

[0035] 3. Evacuation stage:

[0036] After the injection phase is completed, since the dosing module 11, the electrically driven delivery pump 7 and the re-pump module 26 all stop working, uninjected pressurized urea aqueous solution will remain in the space formed by the check valve 22, the suction pipe D23, the filter energy storage device 24 and the injection pipe 9.

[0037] In order to prevent the above-mentioned residual pressurized urea aqueous solution from freezing and cracking the pipeline or / and equipment at low temperature, the device needs to turn on the back-drawing pump module 26 (that is, the electrically driven back-drawing pump 28 and the electromagnetic on-off valve 29 of the back-drawing pump module are turned on at the same time), and when the pressure sensor 13 detects that the pressure of the urea aqueous solution is lower than the specified value, the dosing module 11 is turned on; in this way, the above-mentioned residual pressurized urea aqueous solution is respectively injected into the storage tank 1 through the dosing module 11, the injection pipe 9 and the check valve 22, the suction pipe D23, and then through the filtering energy storage device 24, the back-drawing pipe 25, the back-drawing pump module 26 and the return pipe 27 in sequence; after a period of evacuation time, the device closes the dosing module 11 and the back-drawing pump module 26, that is, the evacuation stage is ended.

[0038] In the present embodiment, the urea aqueous solution injection pressure stabilization effect can be achieved by using the filter energy storage device 24 to intermittently replenish the pressure through the electric drive delivery pump 7 during the injection stage. Compared with the prior art that uses the throttle valve 16 and the pressure valve 14 to continuously overflow and return the liquid through the electric drive delivery pump 7 to achieve the urea aqueous solution injection pressure stabilization effect, the urea metering injection device has a simple structure, and increases the service life and reliability of the electric drive delivery pump 7, while greatly reducing the operating cost of the device. In addition, the switching between the injection and evacuation stages does not require a two-position four-way reversing valve 5 with a complex structure, which greatly reduces the complexity of the device structure, increases its reliability, and reduces its risk of freezing and cracking.

[0039] In addition, the filtering energy storage device 24 of the present embodiment may also be a hollow rubber energy storage filtering device of other structures, and is not limited by the specific structure of the present embodiment.

[0040] The urea aqueous solution of the present embodiment may also be a liquid reducing agent such as AdBlue or AdBlue.

[0041] The above embodiments only illustrate the present invention with a specific electric-driven delivery pump 7, a filtering energy storage device 24, etc. constituting a liquid reducing agent metering injection device. However, as long as all similar devices such as the above-mentioned electric-driven delivery pump 7, the filtering energy storage device 24, etc. can accomplish the idea of ​​the present invention, they all belong to the protection scope of the present invention. Therefore, the present invention is not limited to the above embodiments. Without departing from the spirit and scope of the present invention, the present invention may have various changes and modifications, which all fall within the scope of the present invention to be protected. The protection scope of the present invention is defined by the attached claims and their equivalents.

Claims

1. A liquid reducing agent metering injection device, characterized in that: The device comprises a controller for controlling power supply to equipment in the device, a storage tank (1) for storing liquid reducing agent, a supply branch for extracting the liquid reducing agent in the storage tank (1), a filtering energy storage device (24) for filtering and storing the liquid reducing agent output by the supply branch, an injection branch for ejecting the liquid reducing agent filtered and stored in the filtering energy storage device (24), and a withdrawal branch for withdrawing the liquid reducing agent remaining in the supply branch, the filtering energy storage device (24) and the injection branch after the injection is completed. The supply branch is formed by connecting the storage box (1), the electrically driven delivery pump (7), the check valve (22) and the filtering energy storage device (24) in sequence through a connecting pipe; the injection branch is formed by connecting the filtering energy storage device (24) and the dosing module (11) through a connecting pipe, and a pressure sensor (13) is connected to the connecting pipe between the filtering energy storage device (24) and the dosing module (11); the withdrawal branch is formed by connecting the filtering energy storage device (24), the withdrawal pump module (26) and the storage box (1) in sequence through a connecting pipe, wherein the withdrawal pump module (26) comprises an electrically driven withdrawal pump (28) and an electromagnetic on-off valve (29) connected in series with each other. The electromagnetic on-off valve (29) is disconnected during the period of extracting the liquid reducing agent in the storage tank (1), filtering and storing the liquid reducing agent output from the supply branch, and spraying out the liquid reducing agent filtered and stored in the filtering and energy-storing device (24), and the electromagnetic on-off valve (29) is connected during the period of extracting the liquid reducing agent remaining in the supply branch, the filtering and energy-storing device (24), and the spraying branch after the spraying is completed.

2. The metering injection device according to claim 1, characterized in that: A filter (3) is connected in series on the connecting pipeline between the storage tank (1) and the electrically driven delivery pump (7) in the supply branch.

3. The metering injection device according to claim 1 or 2, characterized in that: The liquid reducing agent is a urea aqueous solution.

4. The metering injection device according to claim 1 or 2, characterized in that: The electrically driven delivery pump (7) is driven by a motor or an electromagnet; the electrically driven withdrawal pump (28) is driven by a motor or an electromagnet.

5. The metering injection device according to claim 1, characterized in that: The filtering energy storage device (24) is a hollow rubber energy storage filtering device.

6. The metering injection device according to claim 2, characterized in that: The filtering energy storage device (24) is a hollow rubber energy storage filtering device.

7. The metering injection device according to claim 5 or 6, characterized in that: The hollow rubber energy storage filter device is mainly composed of a paper filter layer (01), a hollow rubber rod (02) and a cap-shaped outer shell (03); the paper filter layer (01) and the hollow rubber rod (02) are sequentially embedded from an open end of the cap-shaped outer shell (03) and fixed on the outer side of the end through an end cover (04) with a center hole; a liquid reducing agent inlet (05) is arranged at the other end of the outer shell (03) and passes through the paper filter layer (01) directly to the hollow rubber rod (02); a liquid reducing agent injection outlet (07) is arranged in the middle of the side wall of the outer shell (03); and a liquid reducing agent return outlet (06) is arranged at the bottom of the side wall of the outer shell (03).

8. The metering injection device according to claim 5 or 6, characterized in that: The electrically driven delivery pump (7) is driven by a motor or an electromagnet; the electrically driven withdrawal pump (28) is driven by a motor or an electromagnet.

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