Reflux device, urea pump and system for supplying urea solution

Abstract

Embodiments of the present invention disclose a reflux device, a urea pump, and a system for supplying a urea solution. The reflux device includes: a housing in which a chamber is formed and the housing is provided with a first reflux inlet, a second reflux inlet, and a reflux outlet communicating with the chamber; a diaphragm configured to reciprocate within the chamber to enable a fluid to flow into the chamber simultaneously via the first reflux inlet and the second reflux inlet and leave the chamber via the reflux outlet; wherein the diaphragm is configured to close the second reflux inlet when not performing the reciprocating motion such that the fluid can only flow into the chamber via the first reflux inlet and leave the chamber via the reflux outlet.

Description

Technical Field

[0001] The present invention relates to the field of fluid transportation, and more particularly to a reflux device, a urea pump, and a system for supplying urea solution. Background Art

[0002] In order to meet the increasingly stringent exhaust emission standards, the exhaust gas emitted by diesel vehicles is usually post-treated. Currently, the mainstream post-treatment technology in the diesel vehicle market is the Selective Catalytic Reduction (SCR) technology. This SCR technology uses urea solution as a reducing agent to remove nitrogen oxides in the emissions of diesel engines. Related SCR systems generally include a urea solution storage tank, a urea pump, a urea solution nozzle, an electronic control unit, etc. In a high-temperature environment, the urea solution nozzle sprays urea solution into the catalytic reaction module. The urea solution produces water and ammonia at high temperature, and the ammonia undergoes an oxidation-reduction reaction with nitrogen oxides in the exhaust gas in the catalytic reaction module to generate nitrogen and water, thereby achieving the purpose of reducing the nitrogen oxide emissions of diesel engines.

[0003] The urea pump is an important part of the urea solution injection metering system. Its main function is to extract urea solution from the urea tank, maintain a certain pressure, and then transport it to the injection unit. Among them, the overflow solution is refluxed to the urea storage tank through the reflux unit, thereby meeting the requirements of the urea solution injection metering system for flow rate and pressure. The non-air-assisted urea pump mainly has two working processes: pressure building and injection, and back pumping. In order to meet the pressure and normal injection of the injection unit of the urea solution injection metering system, the amount of urea solution transported by the urea pump must be greater than the amount of urea solution required by the injection unit. Therefore, the urea pump also needs a reflux unit to reflux the excess solution during pressure building and injection.

[0004] In addition, when the diesel engine stops running, the urea aqueous solution remaining in the components and pipelines of the urea solution injection metering system may freeze due to low temperature, resulting in cracking of the equipment and pipelines. To prevent this from happening, it is usually necessary to add a back pump for back pumping the pipeline to pump the remaining urea aqueous solution back to the urea aqueous solution storage tank.

[0005] In order to meet the above requirements, a conventional urea pump is configured with a reflux structure. However, the current reflux structure has more parts and a complex assembly structure, which have an adverse impact on the overall layout structure and reflux performance of the urea pump, and the manufacturing cost is relatively high. Summary of the Invention

[0006] In view of this, embodiments of the present invention are expected to provide a reflux device, a urea pump, and a system for supplying urea solution, so as to improve the reflux efficiency and reduce the manufacturing cost with a simple structure.

[0007] The technical solution of the present invention is implemented as follows:

[0008] In a first aspect of an embodiment of the present invention, a reflux device is provided. The reflux device includes: a housing in which a chamber is formed and the housing is provided with a first reflux inlet, a second reflux inlet, and a reflux outlet communicating with the chamber; a diaphragm configured to reciprocate within the chamber such that fluid flows into the chamber via both the first reflux inlet and the second reflux inlet and exits the chamber via the reflux outlet; wherein the diaphragm is configured to close the second reflux inlet when not performing the reciprocating motion such that fluid can only flow into the chamber via the first reflux inlet and exit the chamber via the reflux outlet.

[0009] In a second aspect of an embodiment of the present invention, a urea pump is provided. The urea pump includes: a pressure building pump including an input port and an output port; and a reflux device according to the first aspect, wherein the output port of the pressure building pump communicates with the first reflux inlet and the second reflux inlet of the reflux device.

[0010] In a third aspect of an embodiment of the present invention, a system for supplying a urea solution is provided. The system includes: an injection unit for injecting the urea solution; a liquid storage tank for storing the urea solution; a urea pump according to the second aspect, wherein the output port of the pressure building pump and the first reflux inlet and the second reflux inlet of the reflux device communicate with the injection unit, the input port of the pressure building pump and the reflux outlet of the reflux device do not communicate with each other but respectively communicate with the liquid storage tank, or the input port of the pressure building pump and the reflux outlet of the reflux device communicate with each other and then communicate with the liquid storage tank.

[0011] Embodiments of the present invention provide a reflux device, a urea pump, and a system for supplying urea solution. The reflux device is configured such that when the diaphragm of the reflux device does not reciprocate, the second reflux inlet of the reflux device is closed and fluid can reflux through a first reflux path composed of a first reflux inlet, a chamber, and a reflux outlet; when the diaphragm of the reflux device reciprocates within the chamber, the fluid can reflux through the first reflux path and can also reflux through a second reflux path composed of a second reflux inlet, a chamber, and a reflux outlet. That is to say, the reflux device can provide a first reflux path when the diaphragm is not working, and can provide both the first reflux path and the second reflux path for reflux when the diaphragm is working. Based on the above situation, when the urea pump and the system for supplying urea solution provided by the embodiments of the present invention are working, during the delivery stage of the urea pump, when the reflux outlet of the reflux device is connected to the liquid storage tank, the overflow solution can automatically reflux to the liquid storage tank via the first reflux path, and when the reflux outlet of the reflux device is connected to the input port of the pressure building pump, the overflow solution can reflux to the upstream of the pressure building pump in the form of internal reflux for secondary liquid supply, thereby improving the liquid supply efficiency of the urea pump; during the back-pumping stage of the urea pump, the diaphragm of the reflux device reciprocates within the chamber so that the urea solution remaining in the pipeline can be back-pumped to the liquid storage tank via both the first reflux path and the second reflux path. Compared with conventional urea pumps and systems for supplying urea solution having independent overflow circuits and back-pumping circuits, the urea pump and the system for supplying urea solution provided by the embodiments of the present invention achieve the overflow and back-pumping of urea solution with a simpler structure, ensure the back-pumping efficiency, and can also improve the liquid supply efficiency by making the overflow solution reflux to the pressure building pump for secondary liquid supply. Description of the Drawings

[0012] Figure 1 is a schematic structural diagram of the reflux device of a conventional urea pump;

[0013] Figure 2 is a schematic structural diagram of the reflux device provided by the embodiment of the present invention;

[0014] Figure 3 is a schematic structural diagram of the second housing of the reflux device provided by the embodiment of the present invention;

[0015] Figure 4 is a schematic structural diagram of the third housing of the reflux device provided by the embodiment of the present invention;

[0016] Figures 5a to 5e is a schematic structural diagram of the first reflux inlet of the reflux device provided by the embodiment of the present invention;

[0017] Figure 6Schematic diagram of a system for supplying urea solution provided by an embodiment of the present invention;

[0018] Figure 7 Schematic diagram of a system for supplying urea solution provided by an embodiment of the present invention. Detailed implementation manners

[0019] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention.

[0020] Figure 1 A reflux device BC of a conventional urea pump is shown, and the reflux device BC includes: a back-pumping device SD, a check valve SV, a liquid return valve body BB, and a joint CC. When the urea pump performs an injection operation, the pressure-building pump (not shown) of the urea pump works, the back-pumping device SD is closed, and the excess urea solution enters the reflux device BC from the overflow inlet a1 along the direction shown by arrow B. After opening the check valve SV, it enters the overflow intermediate hole a2, passes through the side wall of the liquid return valve body BB, and then flows into the urea storage tank (not shown) through the outlet a3 of the joint CC. When the urea pump performs a back-pumping operation, the pressure-building pump of the urea pump is closed, the back-pumping device SD works, and the urea solution remaining in each pipeline is pumped into the back-pumping device SD from the back-pumping inlet b1 along the direction shown by arrow A, flows through the back-pumping intermediate hole b2 by the back-pumping device SD to the side wall of the liquid return valve body BB, and finally flows into the urea storage tank through the outlet a3 of the joint CC.

[0021] Since the overflow pipeline and the back-pumping pipeline of the above reflux device BC are formed independently of each other, and the overflow pipeline does not participate in the back-pumping operation at all, the reflux device BC has more parts and a complex assembly structure. Especially the sealed installation of the check valve SV increases great difficulties for the overall structural layout of the urea pump and the realization of the back-pumping performance, with a high manufacturing cost and a low back-pumping efficiency.

[0022] Therefore, optimizing the structure of the reflux device of the urea pump, reducing the assembly difficulty of the urea pump, improving the working performance of the urea pump, and reducing the manufacturing cost are problems that urgently need to be solved in the art.

[0023] To solve the above problems, refer to Figure 2, in the first aspect of the embodiment of the present invention, a reflux device 1 is provided. The reflux device 1 includes: a housing 10, a chamber 101 is formed in the housing 10 and the housing 10 is provided with a first reflux inlet 102, a second reflux inlet 103 and a reflux outlet 104 communicating with the chamber 101; a diaphragm 20, the diaphragm 20 is arranged to be able to reciprocate within the chamber 101 so that fluid flows into the chamber 101 through the first reflux inlet 102 and the second reflux inlet 103 simultaneously and leaves the chamber 101 through the reflux outlet 104; wherein, the diaphragm 20 is arranged to close the second reflux inlet 103 when not performing the reciprocating motion so that fluid can only flow into the chamber 101 through the first reflux inlet 102 and leave the chamber 101 through the reflux outlet 104.

[0024] According to an exemplary embodiment of the present invention, referring to Figure 2 , the housing 10 includes a first housing 10a, a second housing 10b and a third housing 10c coaxially installed, wherein the second housing 10b is located between the first housing 10a and the third housing 10c, the chamber 101 is formed by the first housing 10a and the second housing 10b, the first reflux inlet 102, the second reflux inlet 103 and the reflux outlet 104 are formed through the second housing 10b in the same direction and the second reflux inlet 103 is approximately located at the central position of the second housing 10b, the diaphragm 20 is generally disc-shaped and made of an elastic material so that the diaphragm 20 can undergo elastic deformation when subjected to an external force. In Figure 2 the illustrated embodiment, the diaphragm 20 is installed between the first housing 10a and the second housing 10b such that the peripheral portion of the diaphragm 20 is sealed and clamped between the first housing 10a and the second housing 10b, and the central portion of the diaphragm 20 closes the second reflux inlet 103, but an annular gap is formed between the intermediate portion of the diaphragm 20 between the central portion and the peripheral portion and the bottom of the chamber 101.

[0025] When the diaphragm 20 is stationary in the reflux device, the second reflux inlet 103 is closed, and the fluid can reflux through the first reflux path composed of the first reflux inlet 102, the chamber 101, and the reflux outlet 104; when the central portion of the diaphragm 20 is periodically subjected to an external force to generate elastic deformation and reciprocate within the chamber 101, the diaphragm 20 periodically opens the second reflux inlet 103 and generates a positive pressure or a negative pressure within the chamber 101, enabling the fluid to reflux under the action of the positive pressure and the negative pressure simultaneously through the first reflux path and the second reflux path composed of the second reflux inlet 103, the chamber 101, and the reflux outlet 104. That is to say, the reflux device can provide the first reflux path when the diaphragm 20 is not working, and can provide the first reflux path and the second reflux path for reflux simultaneously when the diaphragm 20 is working. Thus, two reflux modes are realized with a simple structure, the reflux efficiency is improved, and the manufacturing cost is reduced.

[0026] To ensure the reflux operation, refer to Figure 2 , between the second housing 10b and the third housing 10c, a first one-way valve plate 105 is provided at positions corresponding to the first reflux inlet 102 and the second reflux inlet 103, and a second one-way valve plate 106 is provided at the position corresponding to the reflux outlet 104. A total reflux inlet 107 and a total reflux outlet 108 are formed through the third housing 10c. The total reflux inlet 107 is in communication with the first reflux inlet 102 and the second reflux inlet 103, and the total reflux outlet 108 is in communication with the reflux outlet 104. Among them, the first one-way valve plate 105 is arranged to allow the fluid to enter the chamber 101 from the total reflux inlet 107 via the first reflux inlet 102 and the second reflux inlet 103, but to prevent the fluid from flowing back to the total reflux inlet 107 via the first reflux inlet 102 and the second reflux inlet 103. That is to say, the first one-way valve plate 105 can be used for both the first reflux inlet 102 and the second reflux inlet 103 at the same time. As an alternative embodiment, the first one-way valve plate 105 can also be arranged as two one-way valve plates respectively for the first reflux inlet 102 and the second reflux inlet 103; the second one-way valve plate 106 is arranged to allow the fluid to leave the chamber 101 via the reflux outlet 104, but to prevent the fluid from entering the chamber 101 from the total reflux outlet 108 via the reflux outlet 104. Thus, the reflux direction of the fluid is restricted to a single direction from the first reflux inlet 102 and the second reflux inlet 103 of the reflux device, through the chamber 101 to the reflux outlet 104, and leaving the chamber 101 via the reflux outlet 104.

[0027] To simplify the structure and thus reduce the manufacturing cost, preferably, as Figure 2As shown, the first one-way valve plate 105 and the second one-way valve plate 106 can be formed as an integral part, so that only one component can be used for the first reflux inlet 102, the second reflux inlet 103 and the reflux outlet 104 at the same time.

[0028] To prevent the first one-way valve plate 105 and the second one-way valve plate 106 from losing their sealing effectiveness due to contact with the second housing 10b or the third housing 10c after being subjected to the pressure of the fluid, refer to Figure 3 , a first notch 109 is formed in the portion of the second housing 10b opposite to the first one-way valve plate 105, and a first boss 111 protruding downward from the bottom of the first notch 109 is formed at the central position of the bottom of the first notch 109, thereby reducing the contact area of the first one-way valve plate 105 with the second housing 10b after being subjected to the pressure of the fluid, and thus preventing the first one-way valve 105 from losing its sealing effectiveness due to contact with the second housing 10b; in addition, refer to Figure 4 , a second notch 110 is formed in the portion of the third housing 10c opposite to the second one-way valve plate 106, and a second boss 112 protruding upward from the bottom of the second notch 110 is formed at the central position of the bottom of the second notch 110, thereby reducing the contact area of the second one-way valve plate 106 with the third housing 10c after being subjected to the pressure of the fluid, and thus preventing the second one-way valve plate 106 from losing its sealing effectiveness due to contact with the third housing 10c.

[0029] To achieve the reciprocating motion of the diaphragm 20, preferably, refer to Figure 2 , the reflux device further includes a main spring 30 connected to the diaphragm 20, and the main spring 30 is arranged such that: during the reciprocating motion, when the diaphragm 20 moves in the first direction D1, it needs to overcome the elastic restoring force of the main spring 30 and the diaphragm 20 can move in the second direction D2 opposite to the first direction D1 through the elastic restoring force of the main spring 30.

[0030] Figure 2 Shows an example of the arrangement of the main spring 30 provided by the embodiment of the present invention. As Figure 2As shown, the reflux device 1 further includes a first connector 301 and a second connector 302 made of magnetic material, and a coil 303 disposed outside the first connector 301 and the second connector 302. The main spring 30 coaxially connects the first connector 301 and the second connector 302 in a spaced-apart manner from each other, and the first connector 301 coaxially connects the main spring 30 and the diaphragm 20. Wherein, the main spring 30 is installed in the reflux device 1 such that: by pushing the diaphragm 20 against the upper surface of the second housing 10b through the first connector 301, the central portion of the diaphragm 20 can close the second reflux inlet 103. At the same time, an annular gap is left between the intermediate portion of the diaphragm 20 between the central portion and the peripheral portion and the upper surface of the second housing 10b. In this state, the fluid can reflux through the first reflux inlet. When it is necessary to make the diaphragm 20 reciprocate in the chamber 101 to generate a positive pressure and a negative pressure that further promote the reflux of the fluid, the coil 303 can be energized to magnetically adsorb the second connector 302 to the first connector 301. Thereby, the first connector 301 moves toward the second connector 302 against the elastic restoring force of the main spring 30. During this process, the negative pressure generated in the chamber 101 cooperates with the first one-way valve plate 105 and the second one-way valve plate 106 to suck the fluid into the chamber 101 through the first reflux inlet 102 and the second reflux inlet 103 at the same time; once the second connector 302 contacts the first connector 301, the power supply to the coil 303 can be stopped, then the first connector 301 and the diaphragm 20 connected to the first connector 301 will move in a direction away from the second connector 302 under the action of the elastic restoring force of the main spring 30. During this process, the positive pressure generated in the chamber 101 cooperates with the first one-way valve plate 105 and the second one-way valve plate 106 to discharge the fluid in the chamber 101 through the reflux outlet 104. By repeating the above process, the reflux of the fluid can be achieved in a pumping-back manner.

[0031] According to a preferred embodiment of the present invention, referring to Figure 2 , the diaphragm 20 includes a protruding portion 201 protruding from the surface, and the diaphragm 20 is installed in the reflux device such that the protruding portion 201 can cooperate with the second reflux inlet 103 to close the second reflux inlet 103.

[0032] According to an example of the present invention, a second reflux inlet 103 is formed at a substantially central position of the second housing 10b, and a protrusion 201 is formed at a substantially central position of the diaphragm 20 and is formed as an annular protrusion protruding toward the second housing 10b. The inner diameter of the annular protrusion is slightly larger than the diameter of the second reflux inlet 103. Thus, when the diaphragm 20 is placed on the second housing 10b, the annular protrusion can abut against the second housing 10b around the second reflux inlet 103 to close the second reflux inlet 103. When the central portion of the diaphragm 20 reciprocates under an external force, the second reflux inlet 103 will be periodically opened or closed, so that fluid can be simultaneously sucked into the chamber 101 from the first reflux inlet 102 and the second reflux inlet 103 and conveyed out of the chamber 101 via the reflux outlet 104.

[0033] According to a preferred embodiment of the present invention, referring to Figure 2 , the reflux device 1 further includes a filter 40 disposed upstream of the first reflux inlet 102 and the second reflux inlet 103 in the reflux direction of the fluid. As Figure 2 shown, the filter 40 is disposed in the total reflux inlet 107 to filter the fluid flowing into the reflux device 1, thereby preventing the fluid from clogging the first reflux inlet 102.

[0034] According to an exemplary embodiment of the present invention, the first reflux inlet 102 is arranged for the reflux of a small portion of the fluid, and thus has a smaller diameter than the second reflux inlet 103 and the total reflux inlet 107. However, when the fluid enters the first reflux inlet 102 from the total reflux inlet 107, since it is from a large chamber to a small chamber, excessive bubbles will be generated in the fluid, resulting in unstable fluid pressure. Moreover, when the fluid enters the chamber 101 via the first reflux inlet 102 with a smaller diameter, it may cause a certain impact on the diaphragm 20 due to excessive pressure. Therefore, in this case, the structure of the first reflux inlet 102 needs to be further improved.

[0035] To address the above problems, preferably, the first reflux inlet 102 is arranged to include an upstream side portion 1021, a downstream side portion 1022 in the reflux direction of the fluid, and an intermediate portion 1023 located between the upstream side portion 1021 and the downstream side portion 1022. The diameter of the upstream side portion 1021 and the diameter of the downstream side portion 1022 are respectively larger than the diameter of the intermediate portion 1023, thereby reducing the impact on the diaphragm caused by excessive pressure of the reflux fluid and also reducing the tension generated between the diaphragm and the fluid during movement.

[0036] For example, Figures 5a to 5e shows several exemplary configurations of the first reflux inlet 102, where Figure 5eThe first reflux inlet 102 shown in [figure] has a constant diameter, while Figures 5a to 5d the first reflux inlet 102 shown in [figure] can be divided in the reflux direction of the fluid into an upstream side portion 1021, a downstream side portion 1022, and an intermediate portion 1023 located between the upstream side portion 1021 and the downstream side portion 1022. Figure 5a The upstream side portion 1021 shown in [figure] has a shape that tapers towards the intermediate portion 1023, and the downstream side portion 1022 has a constant diameter that is larger than that of the intermediate portion 1023. Figure 5d The first reflux inlet 102 shown in [figure] has a shape that is inverted from Figure 5a the first reflux inlet 102 shown in [figure]. Figure 5b The upstream side portion 1021 and the downstream side portion 1022 shown in [figure] have a constant diameter that is larger than that of the intermediate portion 1023. Figure 5c The upstream side portion 1021 shown in [figure] has a shape that tapers towards the intermediate portion 1023, and the downstream side portion 1022 has a shape that gradually expands away from the intermediate portion 1023. By using Figures 5a to 5d the first reflux inlet 102 shown in [figure], it is possible to facilitate the entry of the reflux fluid, avoid the generation of excessive bubbles in the fluid entering the chamber 101, facilitate the stabilization of the fluid pressure, and reduce the impact of the fluid on the diaphragm.

[0037] To further avoid the generation of excessive bubbles in the fluid entering the chamber 101, the internal structures of the second housing 10b and the third housing 10c can be rounded at the corners, thereby avoiding problems such as a sharp corner causing a reduction in the fluid flow rate, the generation of bubbles, and instability of the fluid flow rate and pressure. For the first reflux inlet 102, it can be directly formed on the second housing 10b, or can be formed as a separate component and then installed on the second housing 10b in a sealed manner.

[0038] Although Figure 2 only one first reflux inlet 102 is provided in the reflux device 1 shown in [figure], however, more first reflux inlets 102 can be provided for the reflux device 1 according to the actual application situation. In addition, the specific position and installation method of the first reflux inlet 102 in the reflux device 1 are not limited to Figure 2 the embodiment shown in [figure], but can also be provided at other positions in the reflux device 1, and can also be installed in other ways, as long as the reflux of the fluid from the first reflux inlet 102 to the reflux outlet 104 can be achieved.

[0039] See Figure 6 and Figure 7, in the second aspect of the embodiments of the present invention, a urea pump 2 is provided. The urea pump 2 includes a pressure - building pump 2A, and the pressure - building pump 2A includes an input port IN and an output port OU; and a reflux device 1 according to the first aspect. Wherein, the output port OU of the pressure - building pump 2A is communicated with the first reflux inlet 102 and the second reflux inlet 103 of the reflux device 1.

[0040] The urea pump 2 has a conveying operation state for pumping urea solution and a back - pumping operation state for sucking back the urea solution remaining in the pipeline. In the conveying operation state, the pressure - building pump 2A works to convey urea solution. At this time, the diaphragm of the reflux device 1 is in a static state of closing the second reflux inlet 103. In order to ensure the pressure of the conveyed urea solution, the amount of urea solution conveyed by the urea pump 2 will be greater than the required amount. Therefore, excess urea solution will be generated at the output port OU. This part of the urea solution can flow back from the output port OU through the first reflux inlet 102, the chamber 101, and the reflux outlet 104 of the reflux device 1, and finally flow out of the urea pump 2. In the back - pumping operation state, the pressure - building pump 2A stops working, and the diaphragm of the reflux device 1 starts to reciprocate to periodically generate positive pressure and negative pressure in the chamber, so that the urea solution remaining in each pipeline and each component of the urea pump 2 can be sucked back through the first reflux inlet 102 and the second reflux inlet 103 of the reflux device 1, and finally flow out of the urea pump.

[0041] Regarding the arrangement manner of the pressure - building pump 2A and the reflux device 1 in the system 3, preferably, refer to Figure 6 , the input port IN of the pressure - building pump 2A is not communicated with the reflux outlet 104 of the reflux device 1; or preferably, refer to Figure 7 , the input port IN of the pressure - building pump 2A is communicated with the reflux outlet 104 of the reflux device 1.

[0042] Refer to Figure 6 and Figure 7 , in the third aspect of the embodiments of the present invention, a system 3 for supplying urea solution is provided. The system 3 includes an injection unit 3A for injecting urea solution; a liquid storage tank 3B for storing urea solution; a urea pump 2 according to the second aspect. Wherein, in the system 3 shown in Figure 6 , the output port OU of the pressure - building pump 2A, the first reflux inlet 102 and the second reflux inlet 103 of the reflux device 1 are communicated with the injection unit 3A, the input port IN of the pressure - building pump 2A is communicated with the liquid storage tank 3B, and the reflux outlet 104 of the reflux device 1 is communicated with the liquid storage tank 3B; in Figure 7In the system 3 shown, the input port IN of the pressure - building pump 2A is connected to the return outlet 104 of the return device 1 and then to the liquid storage tank 3B after connection. The output port OU of the pressure - building pump 2A, the first return inlet 102 and the second return inlet 103 of the return device 1 are connected to the injection unit 3A. The system 3 provided by the embodiment of the present invention is used for injecting urea solution. The system 3 includes a pressure - building injection operation state and a back - pumping operation state. In the pressure - building injection operation state, the pressure - building pump 2A of the urea pump 2 operates to pump the urea solution stored in the liquid storage tank 3B from the input port IN to the output port OU and further to the injection unit 3A. Among them, the amount of urea solution pumped to the injection unit 3A is greater than the amount of urea solution ejected by the injection unit 3A to ensure the pressure of the ejected urea solution. Thus, the excess urea solution will flow back between the upstream of the injection unit 3A and the downstream of the pressure - building pump 2A. At this time, for Figure 6 the system 3 shown, the returned urea solution can directly flow back to the liquid storage tank 3B via the first return inlet 102, the chamber 101 and the return outlet 104 of the return device 1, while for Figure 7 the system 3 shown, the returned urea solution can flow back to the input port IN of the pressure - building pump 2A via the first return inlet 102, the chamber 101 and the return outlet 104 of the return device 1 and enter the pressure - building pump 2A again for secondary liquid supply; in the back - pumping operation state, for Figure 6 and Figure 7 the system 3 shown, the pressure - building pump 2A of the urea pump 2 stops working, and the diaphragm of the return device 1 starts to reciprocate to periodically generate positive pressure and negative pressure in the chamber, so that the urea solution remaining in each pipeline and each component of the system 3 can flow back simultaneously via the first return inlet 102 and the second return inlet 103 of the return device 1 and finally flow back to the urea storage tank 3B through the pipeline.

[0043] For Figure 7 the system 3 shown, since the return outlet 104 of the return device 1 is connected to the inlet IN of the pressure - building pump 2A, when the system 3 performs the pressure - building injection operation, the urea solution flowing back via the return device 1 does not directly flow back to the liquid storage tank 3B, but can be pumped into the pressure - building pump 2A again via the input port IN of the pressure - building pump 2A under the action of the pressure - building pump 2A and then be transported by the pressure - building pump 2A to the injection unit 3A again, that is, be supplied with liquid for the second time, rather than first flowing back to the liquid storage tank 3B and then being pumped out from the liquid storage tank 3B by the pressure - building pump 2A. Thus, it can be seen that Figure 7 the system 3 shown makes more efficient use of the returned urea solution and improves the liquid - supply efficiency.

[0044] According to a preferred embodiment of the present invention, during the pressure - building injection of the system, the amount of the reflux through the reflux device is 2 kg to 20 kg per hour, and more preferably, 2 kg to 14 kg per hour.

[0045] For Figure 7 the system 3 shown in

[0046] In addition, for Figure 6 the system 3 shown in

[0047] According to a preferred embodiment of the present invention, the system 3 further includes a on - off valve disposed upstream of the first reflux inlet 102 and the second reflux inlet 103 of the reflux device 1 or downstream of the reflux outlet 104 of the reflux device 1 in the reflux direction of the fluid, so as to be able to shut off the reflux device 1.

[0048] Specifically, for different application scenarios, optionally, an on - off valve can be added on the upstream side or the downstream side of the first check valve plate 105 of the reflux device 1 in the reflux direction of the fluid, or on the upstream side or the downstream side of the second check valve plate 106 of the reflux device 1 in the reflux direction of the fluid. For example, in Figure 7 the embodiment shown in Figure 7 an on - off valve 2B is provided on the downstream side of the second check valve plate 106 in the reflux direction of the fluid. When building the pressure of the urea pump, especially when

[0049] building the pressure of the internal reflux system shown in Figure 7, preferably, the system 3 includes two of the injection units 3A, wherein each injection unit 3A is configured to be able to operate independently.

[0050] Specifically, the system 3 includes two of the injection units 3A. Through the two injection units 3A, the single injection mode of the system 3 can be achieved, that is, any one of the two injection units 3A can be made to operate only, and the double injection mode of the system 3 can also be achieved through the two injection units 3A, that is, the two injection units 3A can be made to operate simultaneously, and the user can select according to the application situation.

[0051] According to a preferred embodiment of the present invention, referring to Figure 6 and Figure 7 , the system 3 further includes a pressure sensor 3C disposed at the injection unit 3A to sense the pressure of the urea solution delivered to the injection unit 3A, so as to achieve the purpose of monitoring the delivery pressure of the system 3.

[0052] In order to exhaust the pipeline, referring to Figure 7 , preferably, the system 3 further includes an exhaust device 3D disposed at the injection unit 3A, whereby the pressure build-up time can be shortened and the problem of unstable internal pressure of the system 3 can be improved.

[0053] In addition, in order to avoid blockage of the pipeline or each component of the system 3 caused by impurities in the urea solution, optionally, a filter can be added to the system 3. For example, a main filter 3F can be added between the output port OU of the pressure build-up pump 2A and the injection unit 3A; alternatively, a pre-filter 3E can also be added upstream of the input port IN of the pressure build-up pump 2A. In this case, taking the system 3 shown in Figure 7 as an example, the urea solution drawn from the liquid storage tank 3B can first pass through the pre-filter 3E before entering the pressure build-up pump, and the urea solution leaving the urea pump can also be pumped through the exhaust device 3D, the pressure sensor 3C after passing through the main filter 3F, and finally be pumped to the injection unit 3A; similarly, in the pressure build-up injection stage, the urea solution flowing back from upstream of the injection unit 3A passes through the filter 40 disposed at the total return inlet of the return device 1 before flowing through the return device 1, and then is secondarily filled through the input port IN of the pressure build-up pump 2A, and in the back-drawing stage, the urea solution flowing back from upstream of the injection unit 3A passes through the filter 40 disposed at the total return inlet of the return device 1 again before flowing through the return device 1, and then flows into the liquid storage tank 3B through the pre-filter 3E.

[0054] It should be noted that: among the technical solutions recorded in the embodiments of the present invention, they can be arbitrarily combined without conflict.

[0055] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of changes or substitutions, which should all be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims described above.

Claims

1. A reflux device, characterized in that, The reflux device includes: a housing in which a chamber is formed and the housing is provided with a first reflux inlet, a second reflux inlet and a reflux outlet communicating with the chamber; a diaphragm configured to reciprocate within the chamber such that fluid flows into the chamber via the first reflux inlet and the second reflux inlet simultaneously and exits the chamber via the reflux outlet; wherein the diaphragm is configured to close the second reflux inlet when not performing the reciprocating motion such that fluid can only flow into the chamber via the first reflux inlet and exit the chamber via the reflux outlet; the reflux device further includes a main spring connected to the diaphragm, the main spring being configured such that: during the reciprocating motion, when the diaphragm moves in a first direction, it needs to overcome the elastic restoring force of the main spring and the diaphragm can move in a second direction opposite to the first direction by the elastic restoring force of the main spring; the diaphragm includes a protrusion protruding from the surface, and the diaphragm is installed in the reflux device such that the protrusion can cooperate with the second reflux inlet to close the second reflux inlet.

2. The reflux device according to claim 1, characterized in that, the reflux device further includes a filter disposed upstream of the first reflux inlet and the second reflux inlet in the fluid reflux direction to filter the fluid flowing into the reflux device.

3. The reflux device according to claim 1, characterized in that, the first reflux inlet is configured to include an upstream side portion, a downstream side portion and an intermediate portion located between the upstream side portion and the downstream side portion in the fluid reflux direction, wherein the diameters of the upstream side portion and the downstream side portion are respectively larger than the diameter of the intermediate portion.

4. A urea pump, characterized in that, The urea pump includes: a pressure building pump including an input port and an output port; and the reflux device according to any one of claims 1 to 3, wherein the output port of the pressure building pump communicates with the first reflux inlet and the second reflux inlet of the reflux device.

5. The urea pump according to claim 4, characterized in that, the input port of the pressure building pump does not communicate with the reflux outlet of the reflux device.

6. The urea pump according to claim 4, characterized in that, the input port of the pressure building pump and the reflux outlet of the reflux device communicate with each other.

7. A system for supplying urea solution, characterized in that, The system includes: an injection unit for injecting urea solution; a liquid storage tank for storing urea solution; the urea pump according to claim 5, wherein the output port of the pressure building pump and the first reflux inlet and the second reflux inlet of the reflux device communicate with the injection unit, the input port of the pressure building pump communicates with the liquid storage tank, and the reflux outlet of the reflux device communicates with the liquid storage tank.

8. A system for supplying urea solution, characterized in that, The system includes: an injection unit for injecting urea solution; a liquid storage tank for storing urea solution; the urea pump according to claim 6, wherein the input port of the pressure building pump communicates with the liquid storage tank and the output port of the pressure building pump communicates with the injection unit.

9. The system according to claim 8, wherein The system includes two said injection units, wherein each said injection unit is configured to work independently.

10. The system according to claim 8, wherein, In the pressure building injection of the system, the reflux amount of the reflux through the reflux device is 2 kg to 20 kg per hour.

11. The system according to claim 8, wherein The system further includes an on-off valve disposed upstream of the first and second return inlets of the return device or downstream of the return outlet of the return device in the return direction of the fluid, so that the return device can be shut off.

12. The system according to claim 8, wherein The system further includes: a check valve plate disposed at the return outlet of the return device, and an auxiliary spring acting on the check valve plate, wherein the check valve plate and the auxiliary spring are arranged such that the urea solution needs to overcome the elastic restoring force of the auxiliary spring to open the check valve plate before leaving the return device via the return outlet.

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