Reducing agent supply unit and selective catalytic reduction system

Abstract

This utility model relates to a reducing agent supply device and a selective catalytic reduction system, comprising: a suction pipeline; a first filter disposed in the suction pipeline; a pressurization pipeline; a first pump disposed between the suction pipeline and the pressurization pipeline, the first pump being configured to, in a first stage, draw reducing agent from a reducing agent storage tank via the suction pipeline, such that the reducing agent in the reducing agent storage tank flows through the first filter from the front end to the rear end of the filter before being delivered to the pressurization pipeline; the pressurization pipeline being fluidly connected to a return pipeline at the rear end of the first filter; and a second pump disposed in the return pipeline, the second pump being configured to, in a second stage, draw reducing agent from the pressurization pipeline via the return pipeline, such that the reducing agent in the pressurization pipeline flows through the first filter from the rear end to the front end of the filter before being returned to the reducing agent storage tank. This utility model can extend the service life of the first filter.

Description

Technical Field

[0001] This utility model relates to the field of engine exhaust gas treatment, specifically to a reducing agent supply device and a selective catalytic reduction system. Background Technology

[0002] To reduce nitrogen oxides in the exhaust gases produced by the engine during operation, conventional engines are equipped with an SCR (Selective Catalytic Reduction) system.

[0003] A typical SCR system includes a reducing agent tank for storing a reducing agent in the form of an aqueous urea solution, a reducing agent supply device, a metering device, and an injection device. The reducing agent supply device draws the reducing agent from the tank and delivers it to the metering and injection devices, enabling the injection devices to inject the reducing agent into the engine's exhaust pipe at the desired metering rate. The reducing agent supply device includes a suction line, a pressurization line, and a pump located between the suction and pressurization lines. Additionally, a filter is installed in the suction line to filter the reducing agent drawn from the tank.

[0004] Currently, filters generally include filter elements, such as filter screens. The filter elements are arranged on the circumferential inner wall of a portion of the reducing agent storage tank relative to the fluid communication of the suction pipeline. Therefore, the surface area of ​​the filter elements is small and the service life is short, resulting in the need for frequent filter replacement. Utility Model Content

[0005] One object of this invention is to provide a reducing agent supply device to overcome the aforementioned defects.

[0006] According to one aspect of the present invention, a reducing agent supply device is provided, comprising: a suction line configured to be fluidly connected to a reducing agent storage tank; a first filter disposed in the suction line; a pressurization line; a first pump disposed between the suction line and the pressurization line, the first pump being configured to, in a first stage, draw reducing agent from the reducing agent storage tank via the suction line, such that the reducing agent in the reducing agent storage tank flows through the first filter from the front end to the rear end of the filter and is then delivered to the pressurization line; the pressurization line being fluidly connected to a return line at the rear end of the filter of the first filter; and a second pump disposed in the return line, the second pump being configured to, in a second stage, draw reducing agent from the pressurization line via the return line, such that the reducing agent in the pressurization line flows through the first filter from the rear end to the front end of the filter and is then returned to the reducing agent storage tank.

[0007] Optionally, the reducing agent supply device further includes: a pressure regulating line that allows the pressurized line to be in fluid communication with the downstream end of the first filter; and a pressure regulating valve disposed in the pressure regulating line, the pressure regulating valve being configured to allow the reducing agent in the pressurized line to return to the downstream end of the first filter via the pressure regulating line in a first stage to regulate the pressure in the pressurized line, and the pressure regulating valve being further configured to allow the reducing agent in the pressurized line to flow through the pressure regulating line from the downstream end of the first filter to the upstream end of the first filter and then back to the reducing agent storage tank during the period when the first stage ends and the second stage has not yet begun.

[0008] Optionally, the reducing agent supply device further includes a second filter disposed in a pressurized pipeline, a first pump being fluidly connected to the front end of the second filter, and a return pipeline and a pressure regulating pipeline being fluidly connected in parallel to the rear end of the second filter.

[0009] Optionally, the reducing agent supply device further includes: a first port disposed relative to the front end of the first filter, the first port being fluidly connected to the reducing agent storage tank via a suction line; a second port disposed relative to the rear end of the first filter, the second port being fluidly connected to a return line; and a third port disposed relative to the rear end of the first filter, the third port being fluidly connected to a pressure regulating line.

[0010] Optionally, the first filter includes: a housing, the housing including a circumferential wall extending about an axis of the housing and a radial wall extending perpendicular to the axis of the housing, the circumferential wall and the radial wall together defining a cylindrical chamber; and a filter element disposed within the cylindrical chamber about an axis of the housing to define an annular first space between the filter element and the circumferential wall as a filter front end of the first filter, and to define a cylindrical second space within the filter element as a filter rear end of the first filter.

[0011] Optionally, the first port passes through the circumferential wall perpendicular to or at an angle to the housing axis to reach the first space, the second port passes through the radial wall parallel to or at an angle to the housing axis to reach the second space, and the third port passes through the radial wall parallel to or at an angle to the housing axis to reach the second space.

[0012] Optionally, the second port passes through the center of the radial wall, and the third port passes through the radial wall at a position further away from the first port; or the second port passes through the radial wall at a position closer to the first port, and the third port passes through the center of the radial wall.

[0013] Optionally, the first filter includes: a housing, the housing including a circumferential wall extending about an axis of the housing and a radial wall extending perpendicular to the axis of the housing, the circumferential wall and the radial wall together defining a cylindrical chamber; and a filter element disposed within the cylindrical chamber about an axis of the housing to define an annular first space between the filter element and the circumferential wall as a filter rear end of the first filter, and to define a cylindrical second space within the filter element as a filter front end of the first filter.

[0014] Optionally, the first port passes through the radial wall parallel to or at an angle to the housing axis to reach the second space, the second port passes through the circumferential wall perpendicular to or at an angle to the housing axis to reach the first space, and the third port passes through the circumferential wall perpendicular to or at an angle to the housing axis to reach the first space.

[0015] Optionally, the surface area of ​​the filter element is larger than the surface area of ​​the circumferential inner wall of the portion of the reducing agent storage tank into which the fluid of the suction line is connected.

[0016] According to another aspect of the present invention, a selective catalytic reduction system is provided, which includes the above-described reducing agent supply device.

[0017] In the reducing agent supply device and selective catalytic reduction system provided by this invention, the second pump (also known as the back pump) draws the reducing agent from the pressurized pipeline via the return pipeline in the second stage. This allows the reducing agent in the pressurized pipeline to flow through the first filter from the rear end to the front end of the first filter and then back to the reducing agent storage tank. This helps to flush the filter components, so that particles or other impurities adhering to the filter components at the front end of the first filter in the first stage are flushed back to the reducing agent storage tank, thus extending the service life of the first filter. Furthermore, unlike the prior art where the filter components are fluidly connected to a portion of the reducing agent storage tank (i.e., corresponding to the first suction pipeline section) on the circumferential inner wall, the first filter of this invention is set independently or separately from the first suction pipeline section. This significantly increases the volume of the first filter and the surface area of ​​the filter components, thus facilitating the full lifespan of the first filter; that is, the first filter does not need to be replaced during the service life of the reducing agent supply device.

[0018] Other features and advantages of the present invention will become clear from the following detailed description of exemplary embodiments of the present invention with reference to the accompanying drawings. Attached Figure Description

[0019] The accompanying drawings, which form part of this specification, illustrate embodiments of the present invention and, together with the specification, serve to explain the principles of the present invention.

[0020] Figure 1This is a schematic block diagram of an SCR system according to one embodiment of the present invention, wherein the reducing agent supply device is in the first stage.

[0021] Figure 2 This is a schematic block diagram of an SCR system according to one embodiment of the present invention, wherein the reducing agent supply device is in the second stage.

[0022] Figure 3 This is a schematic block diagram of an SCR system according to one embodiment of the present invention, wherein the reducing agent supply device is in the period between the end of the first stage and the beginning of the second stage.

[0023] Figure 4 This is a simplified longitudinal sectional view of the first filter of a reducing agent supply device according to one embodiment of the present invention.

[0024] Figure 5 yes Figure 4 A simplified cross-sectional view of the first filter.

[0025] Figure 6 This is a simplified cross-sectional view of the first filter of a reducing agent supply device according to another embodiment of the present invention.

[0026] Figure 7 This is a simplified longitudinal sectional view of the first filter of a reducing agent supply device according to yet another embodiment of the present invention. Detailed Implementation

[0027] In this document, common technologies and structures of SCR systems known to those skilled in the art may not be discussed in detail, but where appropriate, these technologies and structures should be considered part of the specification.

[0028] Figure 1 This is a schematic block diagram of an SCR system 10 according to one embodiment of the present invention. The SCR system 10 includes a reducing agent tank 12 for storing a reducing agent in the form of a urea aqueous solution, a reducing agent supply device 14 (as enclosed in the dashed box), a metering device 16, and an injection device (not shown). The reducing agent supply device 14 draws the reducing agent from the reducing agent tank 12 and delivers it to the metering device 16 and the injection device, so that the injection device can inject the reducing agent into the exhaust pipe of the engine according to the desired metering.

[0029] Specifically, the reducing agent supply device 14 includes: suction pipes 18a and 18b configured to be in fluid communication with the reducing agent storage tank 12; and a first filter 20 disposed in the suction pipes 18a and 18b. For example, the suction pipes 18a and 18b are divided into a first suction pipe section 18a and a second suction pipe section 18b by the first filter 20. One end of the first suction pipe section 18a is in fluid connection to the reducing agent storage tank 12, and the other end of the first suction pipe section 18a is in fluid connection to the first filter. The filter front end 20a of the first filter 20 is fluidly connected to one end of the second suction pipe section 18b; the other end of the second suction pipe section 18b is fluidly connected to the pump front end 22a of the first pump 22; the pressurization pipes 24a and 24b are fluidly connected to the pump rear end 22b of the first pump 22, that is, the first pump 22 is located between the suction pipes 18a and 18b and the pressurization pipes 24a and 24b. Figure 1 As shown, the first pump 22 is configured to operate in the first stage (i.e., the operation stage of the reducing agent supply device 14) to draw reducing agent from the reducing agent storage tank 12 via the suction lines 18a, 18b as indicated by the arrows, so that the reducing agent in the reducing agent storage tank 12 flows through the first filter 20 in the direction from the front end 20a of the first filter 20 to the rear end 20b of the first filter 20 before being delivered to the pressurization lines 24a, 24b.

[0030] The first pump 22 can be used in conjunction with the one-way valve 26 so that the reducing agent in the reducing agent storage tank 12 flows only from the suction lines 18a, 18b to the pressurization lines 24a, 24b.

[0031] The front end 20a and the rear end 20b of the first filter 20 are separated by the filter element 28 of the first filter 20. The filter element 28 may include a filter screen or other filter elements with physical filtration function.

[0032] Specifically, in the first stage, the front end 20a of the first filter 20 receives reducing agent from the reducing agent storage tank 12 via the first suction pipe section 18a, and the reducing agent further flows through the filter element 28 to reach the rear end 20b of the first filter 20. Particles or other impurities in the reducing agent are intercepted by the filter element 28 at the front end 20a of the first filter 20, that is, the reducing agent is filtered. The front end 22a of the first pump 22 receives the filtered reducing agent from the rear end 20b of the first filter 20 via the second suction pipe section 18b of the suction pipes 18a, 18b, and pressurizes the filtered reducing agent as it flows from the front end 22a to the rear end of the pump 22, so that the pressure of the reducing agent in the pressurization pipes 24a, 24b is greater than the pressure of the reducing agent in the suction pipes 18a, 18b. Thus, the injection device can inject reducing agent into the exhaust pipe of the engine according to the desired metering.

[0033] A second filter 30 (also called a high-pressure filter) can be installed in the pressurization lines 24a and 24b to further filter the reducing agent in the pressurization lines 24a and 24b. Furthermore, a pressure sensor 32 can be installed in the pressurization lines 24a and 24b to detect the pressure of the reducing agent in the pressurization lines 24a and 24b.

[0034] The configuration of the second filter 30 can be similar to that of the first filter 20. That is, the second filter 30 can also include a filter element 30c and a filter front end 30a and a filter back end 30b separated by the filter element 30c. Since the first filter 20 initially filters the reducing agent in the reducing agent storage tank 12, and the second filter 30 subsequently filters the reducing agent filtered by the first filter 20, the filtration load of the first filter 20 is significantly higher than that of the second filter 30. The surface area of ​​the filter element 28 of the first filter 20 can be equal to or greater than the surface area of ​​the filter element 30c of the second filter 30.

[0035] For example, pressurized lines 24a and 24b are divided into a first pressurized line section 24a and a second pressurized line section 24b by the second filter 30. One end of the first pressurized line section 24a is fluidly connected to the pump rear end 22b of the first pump 22, and the other end of the first pressurized line section 24a is fluidly connected to the filter front end 30a of the second filter 30. One end of the second pressurized line section 24b is fluidly connected to the filter rear end 30b of the second filter 30, and the other end of the second pressurized line section 24b is fluidly connected to the pressure sensor 32. Finally, the second pressurized line section 24b and the pressure sensor 32 are fluidly connected to the metering device 16.

[0036] The reducing agent supply device 14 further includes: return lines 33a, 33b that connect pressurized lines 24a, 24b to the downstream end 20b of the first filter 20; and a second pump 35, also referred to as a backflow pump, disposed in the return lines 33a, 33b. Specifically, the return lines 33a, 33b are divided by the second pump 35 into a first return line section 33a and a second return line section 33b. One end of the first return line section 33a is fluidly connected to the downstream end 30b of the second filter 30, and the other end of the first return line section 33a is fluidly connected to the front end of the second pump 35. The rear end of the second pump 35 is fluidly connected to one end of the second return line section 33b, and the other end of the second return line section 33b is fluidly connected to the downstream end 20b of the first filter 20. The second pump 35 is configured to stop in the first stage, that is, the reducing agent is not circulated in the return lines 33a, 33b in the first stage. Figure 2 As shown, the second pump 35 is configured to operate in the second stage (i.e., the post-operation stage of the reducing agent supply device 14) after the completion of the first stage, to draw reducing agent from the pressurized lines 24a, 24b and the optional second filter 30 via the return lines 33a, 33b, as indicated by the arrows, such that the reducing agent in the pressurized lines 24a, 24b and the optional second filter 30 flows through the first filter 20 from the rear end 20b to the front end and then returns to the reducing agent storage tank 12. Simultaneously, the first pump 22 stops in the second stage.

[0037] In the first stage, particles or other impurities in the reducing agent are intercepted by the filter element 28 of the first filter 20 at the filter front end 20a, and are very likely to adhere to the filter element 28. The continuous accumulation of particles or other impurities on the filter element 28 of the first filter 20 will cause the first filter 20 to become clogged, hindering the flow of the reducing agent through the filter element 28, thus negatively affecting the pressure of the reducing agent built up by the first pump 22 in the pressurization lines 24a, 24b, and consequently negatively affecting the injection device's ability to inject the reducing agent into the engine's exhaust pipe at the desired metering. In the second stage, the reducing agent in the pressurization lines 24a, 24b flows through the first filter 20 from the filter rear end 20b to the filter front end, which helps to flush the filter element 28, allowing particles or other impurities adhering to the filter element 28 at the filter front end 20a of the first filter 20 to be flushed back into the reducing agent reservoir 12, thereby extending the service life of the first filter 20. This differs from the reducing agent supply device 14 in the prior art. In the prior art, the reducing agent supply device 14 generally makes the other end of the second return pipe section 33b directly fluidly connected to the reducing agent storage tank 12, and does not help flush the filter component 28.

[0038] The reducing agent supply device 14 further includes: pressure regulating lines 34a and 34b that connect pressurized lines 24a and 24b to the downstream end 20b of the first filter 20; and a pressure regulating valve 36 disposed in the pressure regulating lines 34a and 34b. Specifically, the pressure regulating lines 34a and 34b are divided into a first pressure regulating line section 34a and a second pressure regulating line section 34b by the pressure regulating valve 36. One end of the first pressure regulating line section 34a is connected to the downstream end 30b of the second filter 30, and the other end of the first pressure regulating line section 34a is connected to the upstream end of the pressure regulating valve 36. One end of the second pressure regulating line section 34b is connected to the downstream end of the pressure regulating valve 36, and the other end of the second pressure regulating line section 34b is connected to the downstream end 20b of the first filter 20.

[0039] The pressure regulating valve 36 is configured to allow the reducing agent in the pressurized lines 24a, 24b to return to the downstream end 20b of the first filter 20 via the pressure regulating lines 34a, 34b in the first stage, thereby regulating the pressure of the reducing agent in the pressurized lines 24a, 24b. The pressure regulating valve 36 can be configured as a throttle valve and a check valve 38 used in conjunction with the throttle valve, so that the reducing agent in the pressurized lines 24a, 24b flows only from the first pressure regulating line section 34a to the second pressure regulating line section 34b, and ultimately to the downstream end 20b of the first filter 20. In the first stage, the reducing agent flowing to the downstream end 20b of the first filter 20 will be drawn back into the pressurized lines 24a, 24b by the first pump 22, and will not flow to the reducing agent storage tank 12. Therefore, the reducing agent that has already flowed to the reducing agent supply device 14 in the first stage will flow in an internal circulation manner, which differs from the reducing agent supply device 14 in the prior art. In the prior art, the reducing agent supply device 14 generally makes the other end of the second pressure regulating pipeline section 34b directly fluidly connected to the reducing agent storage tank 12, so that the reducing agent flows through the reducing agent storage tank 12 in a circulation manner.

[0040] In addition, such as Figure 3 As shown, the pressure regulating valve 36 is also configured to allow the reducing agent in the pressurized lines 24a, 24b to flow through the pressure regulating lines 34a, 34b from the filter back end 20b to the filter front end of the first filter 20 and then back to the reducing agent reservoir 12 during the period when the first stage ends and the second stage has not yet started (i.e., both the first pump 22 and the second pump 35 are stopped), as indicated by the arrow, in order to help flush the filter components 28 in advance before the second stage.

[0041] Thus, it can be seen that, on the one hand, the suction lines 18a and 18b and the pressurization lines 24a and 24b are connected in series, and on the other hand, the return lines 33a and 33b, the pressure regulating lines 34a and 34b, and the series-connected suction lines 18a and 18b and pressurization lines 24a and 24b are connected in parallel.

[0042] Figure 4 and Figure 5 These are simplified longitudinal and simplified transverse sectional views of the first filter 20 of the reducing agent supply device 14 according to one embodiment of the present invention. Figure 4 and Figure 5 As shown, the reducing agent supply device 14 includes a first port 40 disposed relative to the filter front end 20a of the first filter 20, and the first port 40 is in fluid communication with the reducing agent storage tank 12 via a first suction pipe section 18a. The reducing agent supply device 14 also includes a second port 42 disposed relative to the filter rear end 20b of the first filter 20, and the second port 42 is in fluid connection to the other end of the second return pipe section 33b. The reducing agent supply device 14 also includes a third port 44 disposed relative to the filter rear end 20b of the first filter 20, and the third port 44 is in fluid connection to the other end of the second pressure regulating pipe section 34b.

[0043] Specifically, the first filter 20 includes: a housing 46, the housing 46 including a circumferential wall 46a extending about the housing axis L and a radial wall 46b extending perpendicular to the housing axis L, the circumferential wall 46a and the radial wall 46b together defining cylindrical chambers 50, 52 within the housing 46; and a filter element 28, such as a filter screen, the filter element 28 being disposed about the housing axis L within the cylindrical chambers 50, 52 to define an annular first space 50 between the filter element 28 and the circumferential wall 46a of the housing 46 as a filter front end 20a of the first filter 20, and defining a cylindrical second space 52 within the filter element 28 as a filter rear end 20b of the first filter 20.

[0044] The first port 40 passes through the circumferential wall 46a, for example perpendicular to or at an angle to the housing axis L, to reach the first space 50. The second port 42 passes through the radial wall 46b, for example parallel to or at an angle to the housing axis L, to reach the second space 52. The third port 44 passes through the radial wall 46b, for example parallel to or at an angle to the housing axis L, to reach the second space 52.

[0045] like Figure 4 and Figure 5 As shown, the second port 42 can pass through the radial wall 46b at a position closer to the first port 40, and the third port 44 can pass through the center of the radial wall 46b.

[0046] Optionally, such as Figure 6 As shown, the second port 42 can pass through the center of the radial wall 46b, and the third port 44 can pass through the radial wall 46b at a position further away from the first port 40.

[0047] Figure 7 The first filter 20' shown is with Figure 4 and Figure 5 The first filter 20 shown is similar to and continues the design. Figure 4 and Figure 5 Similar reference numerals are used for similar components in the accompanying drawings. The difference between the first filter 20' and the first filter 20 is that the first space 50 is used as the filter rear end 20b of the first filter 20, and the second space 52 is used as the filter front end 20a of the first filter 20. Thus, the first port 40 passes through the radial wall 46b parallel to or at an angle to the housing axis L to reach the second space 52, the second port 42 passes through the circumferential wall 46a perpendicular to or at an angle to the housing axis L to reach the first space 50, and the third port 44 passes through the circumferential wall 46a perpendicular to or at an angle to the housing axis L to reach the first space 50.

[0048] Here, the surface area of ​​the filter element 28 is significantly larger than the surface area of ​​the circumferential inner wall of the first suction pipe section 18a. For example, the surface area of ​​the radial wall 46b is also significantly larger than the cross-sectional area of ​​the first suction pipe section 18a, and larger than the cross-sectional area of ​​the second return pipe section 33b and the cross-sectional area of ​​the second pressure regulating pipe section 34b. Unlike the prior art where the filter element 28 is fluidly connected to a portion of the reducing agent storage tank 12 (i.e., corresponding to the first suction pipe section 18a) relative to the suction pipes 18a and 18b, the first filter 20 of this invention is disposed independently of or separated from the first suction pipe section 18a. This significantly increases the volume of the first filter 20 and the surface area of ​​the filter element 28 of the first filter 20, thereby facilitating the full lifespan of the first filter 20, i.e., the first filter 20 does not need to be replaced during the service life of the reducing agent supply device 14.

[0049] While some specific embodiments of the present invention have been described in detail by way of examples, those skilled in the art should understand that the above examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Those skilled in the art should understand that modifications can be made to the above embodiments without departing from the scope and spirit of the present invention. The scope of the present invention is defined by the appended claims.

Claims

1. A reducing agent supply device (14), characterized by, include: Suction lines (18a, 18b) are configured to be in fluid communication with reducing agent storage tank (12); A first filter (20) is installed in the suction lines (18a, 18b); Pressurized piping (24a, 24b); A first pump (22) is provided between the suction line (18a, 18b) and the pressurization line (24a, 24b). The first pump (22) is configured to draw reducing agent from the reducing agent storage tank (12) via the suction line (18a, 18b) in the first stage, so that the reducing agent in the reducing agent storage tank (12) flows through the first filter (20) from the front end (20a) of the first filter (20) to the back end of the filter before being delivered to the pressurization line (24a, 24b). This allows the pressurized lines (24a, 24b) to be in fluid communication with the return lines (33a, 33b) of the filter downstream (20b) of the first filter (20); and A second pump (34) is installed in the return line (33a, 33b). The second pump (34) is configured to draw the reducing agent in the pressurized line (24a, 24b) via the return line (33a, 33b) in the second stage, so that the reducing agent in the pressurized line (24a, 24b) flows through the first filter (20) from the filter end (20b) to the filter front end (20a) and then flows back to the reducing agent storage tank (12).

2. The reducing agent supply device (14) according to claim 1, characterized in that The reducing agent supply device (14) also includes: This allows the pressurized lines (24a, 24b) to be in fluid communication with the pressure regulating lines (34a, 34b) at the filter end (20b) of the first filter (20); and A pressure regulating valve (36) is provided in the pressure regulating lines (34a, 34b). The pressure regulating valve (36) is configured to allow the reducing agent in the pressurized lines (24a, 24b) to return to the filter end (20b) of the first filter (20) via the pressure regulating lines (34a, 34b) in the first stage to regulate the pressure in the pressurized lines (24a, 24b). The pressure regulating valve (36) is also configured to allow the reducing agent in the pressurized lines (24a, 24b) to flow through the pressure regulating lines (34a, 34b) from the filter end (20b) of the first filter (20) to the filter front end and then back to the reducing agent storage tank (12) during the period when the first stage ends and the second stage has not yet started.

3. The reducing agent supply device (14) according to claim 2, characterized in that The reducing agent supply device (14) also includes a second filter (30) disposed in a pressurization line (24a, 24b), a first pump (22) being fluidly connected to the front end of the second filter (30), and a return line (33a, 33b) and a pressure regulating line (34a, 34b) being fluidly connected in parallel to the back end of the second filter (30).

4. The reducing agent supply device (14) according to claim 2, characterized in that The reducing agent supply device (14) also includes: A first port (40) is provided relative to the filter front end (20a) of the first filter (20), and the first port (40) is fluidly connected to the reducing agent storage tank (12) via suction pipes (18a, 18b); A second port (42) is provided relative to the filter back end (20b) of the first filter (20), and the second port (42) is fluidly connected to the return line (33a, 33b); and A third port (44) is provided relative to the filter back end (20b) of the first filter (20), and the third port (44) is fluidly connected to the pressure regulating line (34a, 34b).

5. The reducing agent supply device (14) according to claim 4, characterized in that The first filter (20) includes: a housing (46) including a circumferential wall (46a) extending about a housing axis (L) and a radial wall (46b) extending perpendicular to the housing axis (L), the circumferential wall (46a) and the radial wall (46b) together defining a cylindrical chamber; and a filter element (28) disposed about the housing axis (L) within the cylindrical chamber to define an annular first space (50) between the filter element (28) and the circumferential wall (46a) as a filter front end (20a) of the first filter (20), and a cylindrical second space (52) defined within the filter element (28) as a filter rear end (20b) of the first filter (20).

6. The reducing agent supply device (14) according to claim 5, characterized in that The first port (40) passes through the circumferential wall (46a) perpendicular to or at an angle to the housing axis (L) to reach the first space (50), the second port (42) passes through the radial wall (46b) parallel to or at an angle to the housing axis (L) to reach the second space (52), and the third port (44) passes through the radial wall (46b) parallel to or at an angle to the housing axis (L) to reach the second space (52).

7. The reducing agent supply device (14) according to claim 6, characterized in that The second port (42) passes through the center of the radial wall (46b), and the third port (44) passes through the radial wall (46b) at a position further away from the first port (40); or The second port (42) passes through the radial wall (46b) closer to the first port (40) and the third port (44) passes through the center of the radial wall (46b).

8. The reducing agent supply device (14) according to claim 4, characterized in that The first filter (20) includes: a housing (46) including a circumferential wall (46a) extending about a housing axis (L) and a radial wall (46b) extending perpendicular to the housing axis (L), the circumferential wall (46a) and the radial wall (46b) together defining a cylindrical chamber; and a filter element (28) disposed about the housing axis (L) within the cylindrical chamber to define an annular first space (50) between the filter element (28) and the circumferential wall (46a) as a filter rear end (20b) of the first filter (20), and a cylindrical second space (52) defining within the filter element (28) as a filter front end (20a) of the first filter (20).

9. The reducing agent supply device (14) according to claim 8, characterized in that The first port (40) passes through the radial wall (46b) parallel to or at an angle to the housing axis (L) to reach the second space (52), the second port (42) passes through the circumferential wall (46a) perpendicular to or at an angle to the housing axis (L) to reach the first space (50), and the third port (44) passes through the circumferential wall (46a) perpendicular to or at an angle to the housing axis (L) to reach the first space (50).

10. The reducing agent supply device (14) according to any one of claims 5 to 9, characterized in that, The surface area of ​​the filter element (28) is greater than the surface area of ​​the circumferential inner wall of the part of the fluid communication between the suction line (18a, 18b) and the reducing agent storage tank (12).

11. A selective catalytic reduction system (10), characterized in that, Includes a reducing agent supply device (14) according to any one of claims 1 to 10.

Images