Urea pressure sensor

Abstract

The utility model belongs to the technical field of sensors, and discloses a urea pressure sensor, which comprises an anti-expansion mechanism provided with a liquid inlet channel and a pressure buffer chamber, and the pressure buffer chamber is arranged around the periphery of the liquid inlet channel; the pressure sensing core body mechanism is provided with a pressure sensing surface, and the pressure sensing surface is located on the side, close to the liquid outlet of the liquid inlet channel, of the pressure sensing core body mechanism; and the signal conversion mechanism is electrically connected with the pressure sensing core body mechanism and is used for converting a pressure signal detected by the pressure sensing core body mechanism into an electric signal. The urea pressure sensor solves the problem that the pressure chip induction sheet in the urea pressure sensor in the prior art is easy to be extruded and lose efficacy.

Description

Technical Field

[0001] The utility model belongs to the technical field of sensors, and particularly relates to a urea pressure sensor. Background Art

[0002] The urea pressure sensor is a sensor used in the selective catalytic reduction (SCR) urea injection system for the post-treatment of diesel engine exhaust. Due to the increasing requirements for environmental protection, higher requirements are put forward for the exhaust emissions of diesel engines. The particulate matter and nitrogen oxides (NOx) generated by diesel engines are the two main pollutants in emissions. From the current technical approaches to reducing vehicle exhaust emissions, to meet the Euro IV emission standards, generally no measures are taken from the structure of the engine itself. Usually, the post-treatment of exhaust gas is adopted to reduce the emissions of pollutants, and the urea-SCR selective catalytic reduction method is the most practical method, which can reduce NOx in engine exhaust by more than 50%. A typical urea-SCR system needs to be equipped with a relatively complex injection and control system for adjusting the injection amount of the reducing agent on the basis of the original exhaust gas purification system. The urea pressure sensor is a sensor used in the SCR urea injection system for the post-treatment of diesel engine exhaust, and is used to detect the urea pressure, so as to help determine the urea injection amount.

[0003] Since the urea pressure sensor needs to work in a urea environment for a long time, when the vehicle is turned off and the SCR system stops working, there will be residual urea liquid in the liquid inlet hole and pipeline of the urea pressure sensor. The residual urea liquid will form urea crystals at low temperatures, and the volume of urea will expand violently after crystallization. Since the pressure core is directly installed in the stainless steel shell, the urea crystals will squeeze the core, greatly reducing the service life of the urea pressure sensor, and even being cracked by extrusion, resulting in sensor failure.

[0004] Therefore, the existing urea pressure sensor is equipped with an antifreeze plug made of rubber material at the liquid inlet position, so that the urea crystals do not directly squeeze the core diaphragm but the antifreeze plug. However, the pressure offset by this type of antifreeze plug due to crystallization is limited and cannot completely offset the expansion force of crystallization, resulting in the sensing sheet of the pressure core being squeezed and failing. Summary of the Utility Model

[0005] The utility model provides a urea pressure sensor to solve the problem that the sensing sheet of the pressure chip in the existing urea pressure sensor is easily squeezed and fails.

[0006] To solve the above technical problems, the utility model provides a urea pressure sensor, including:

[0007] An anti-expansion mechanism, an inlet liquid channel and a pressure buffer chamber are arranged on the anti-expansion mechanism, and the pressure buffer chamber is arranged around the periphery of the inlet liquid channel;

[0008] A pressure-sensing core mechanism, the pressure-sensing core mechanism has a pressure-sensing surface, and the pressure-sensing surface is located on one side of the pressure-sensing core mechanism close to the liquid outlet of the inlet liquid channel;

[0009] A signal conversion mechanism, electrically connected to the pressure-sensing core mechanism, for converting the pressure signal detected by the pressure-sensing core mechanism into an electrical signal.

[0010] Optionally, the anti-expansion mechanism has a first anti-expansion member and a second anti-expansion member, the diameter of the second anti-expansion member along the expansion direction is greater than the diameter of the first anti-expansion member along the expansion direction, and the second anti-expansion member is close to the pressure-sensing core mechanism, and the first anti-expansion member is far from the pressure-sensing core mechanism.

[0011] Optionally, the first anti-expansion member is a cylinder, and the diameter direction of the cylinder is consistent with the expansion direction of the anti-expansion mechanism.

[0012] Optionally, the anti-expansion mechanism is an elastic member.

[0013] Optionally, the anti-expansion mechanism further includes a support member, the support member is embedded inside the anti-expansion mechanism, and the support member supports between the opposite ends of the anti-expansion mechanism along a first direction, and the first direction is perpendicular to the expansion direction of the anti-expansion mechanism.

[0014] Optionally, the cross-section of the inlet liquid channel is circular.

[0015] Optionally, the pressure buffer chamber is an annular cavity.

[0016] Optionally, the pressure-sensing core mechanism includes a diffused silicon oil-filled core.

[0017] Optionally, the pressure-sensing core mechanism further includes a first metal shell, and the first metal shell is arranged around the periphery of the diffused silicon oil-filled core.

[0018] Optionally, the urea pressure sensor further includes a second metal shell, the second metal shell is arranged outside the anti-expansion mechanism, the pressure-sensing core mechanism and the signal conversion mechanism, and the edge of the second metal shell is hermetically welded to the edge of the first metal shell.

[0019] Compared with the prior art, a urea pressure sensor provided by the present utility model has the following beneficial effects:

[0020] The utility model is provided with a pressure buffer chamber on the anti-expansion mechanism, and the pressure buffer chamber is arranged around the liquid inlet channel. Even if the urea solution in the liquid inlet channel crystallizes to generate extrusion pressure, due to the buffer space of the pressure buffer chamber, when being extruded by the extrusion pressure, the extrusion pressure can be eliminated as much as possible by extruding the buffer space, protecting the sensing sheet of the pressure core from being extruded.

[0021] In addition, since the pressure buffer chamber is arranged around the liquid inlet channel, when the liquid inlet channel is extruded by urea crystallization, the extrusion pressure received by the entire periphery of the liquid inlet channel can be eliminated. The urea pressure sensor in the prior art only installs an anti-freezing plug at the position of the liquid inlet, so it can only offset the extrusion pressure of urea crystallization on the position of the liquid inlet. Obviously, the urea pressure sensor in the utility model can eliminate a larger extrusion area of urea crystallization and has a better effect of offsetting the extrusion pressure of urea crystallization.

[0022] Furthermore, the anti-freezing plug in the prior art is only made of rubber material, so it only uses the elastic property of the anti-freezing plug itself to buffer the extrusion pressure of urea crystallization, and the extrusion pressure it can offset is limited. The utility model is provided with a pressure buffer chamber, and the extrusion pressure of urea crystallization is offset through the buffer space. Obviously, this can offset more extrusion pressure than using the property of the anti-freezing plug itself.

[0023] In summary, the urea pressure sensor provided in the utility model can effectively offset the extrusion pressure generated by urea crystallization, so as to solve the problem that the sensing sheet of the pressure chip in the urea pressure sensor in the prior art is easily extruded and fails. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only a part of the embodiments of the present invention, rather than all the embodiments. For those of ordinary skill in the art, without creative efforts, other drawings obtained based on these drawings all belong to the scope of protection of the present invention.

[0025] Figure 1 is an exploded view of a urea pressure sensor provided by an embodiment of the present invention;

[0026] Figure 2 is an exploded view of another urea pressure sensor provided by an embodiment of the present invention;

[0027] Figure 3 is a sectional view of a urea pressure sensor provided by an embodiment of the present invention;

[0028] Figure 4This is a three-dimensional structure diagram of a urea pressure sensor provided by an embodiment of the present utility model.

[0029] Description of the drawings: 100 - anti-expansion mechanism, 110 - liquid inlet channel, 111 - first liquid inlet channel, 112 - second liquid inlet channel, 120 - pressure buffer chamber, 130 - first anti-expansion member, 140 - second anti-expansion member, 200 - pressure-sensing core mechanism, 210 - pressure-sensing surface, 220 - diffused silicon oil-filled core, 230 - first metal shell, 300 - signal conversion mechanism, 400 - accommodation groove, 410 - reinforcing rib, 500 - connecting part, 510 - parallel groove, 600 - second metal shell. Detailed implementation manners

[0030] In order to make the objectives, technical solutions and advantages of the present utility model clearer and more understandable, the present utility model will be further described in detail below with reference to the drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present utility model and are not used to limit the present utility model.

[0031] In order to make the description of the present disclosure more detailed and complete, the following provides an illustrative description of the implementation manners and specific embodiments of the present utility model; however, this is not the only form for implementing or applying the specific embodiments of the present utility model. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without making creative efforts fall within the scope of protection of the present utility model.

[0032] It should be noted that the terms "first", "second", etc. in the description and claims of the present utility model and the above drawings are used to distinguish similar objects and do not necessarily need to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of the present utility model described herein can be implemented in an order other than those illustrated or described herein.

[0033] In addition, in the description of the embodiments of the present utility model, "a plurality of" means two or more than two, and other quantifiers are similar. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present utility model and are not used to limit the present utility model, and the embodiments of the present utility model and the features in the embodiments can be combined with each other without conflict.

[0034] As Figure 1 and Figure 2 shown is an exploded view of a urea pressure sensor provided by an embodiment of the present utility model, including:

[0035] The anti-expansion mechanism 100, as Figure 3The figure shows a cross-sectional view of a urea pressure sensor provided by an embodiment of the present utility model. An inlet channel 110 and a pressure buffer chamber 120 are provided on the anti-expansion mechanism 100, and the pressure buffer chamber 120 is disposed around the periphery of the inlet channel 110;

[0036] A pressure sensing core mechanism 200, the pressure sensing core mechanism 200 having a pressure sensing surface 210, the pressure sensing surface 210 being located on a side of the pressure sensing core mechanism 200 close to the liquid outlet of the inlet channel 110;

[0037] A signal conversion mechanism 300, electrically connected to the pressure sensing core mechanism 200, for converting a pressure signal detected by the pressure sensing core mechanism 200 into an electrical signal.

[0038] It should be noted that the inlet channel 110 can be located at any position on the anti-expansion mechanism 100, but it is necessary to ensure that the liquid inlet of the inlet channel 110 is directly opposite to the pressure sensing surface 210 of the pressure sensing core mechanism 200.

[0039] It should be noted that the width and length of the inlet channel 110 can be set according to specific requirements during application.

[0040] Optionally, as Figure 3 shown, the inlet channel 110 may include a first inlet channel 111 and a second inlet channel 112. The first inlet channel 111 is far from the pressure sensing surface 210 of the pressure sensing core mechanism 200, and the second inlet channel 112 is close to the pressure sensing surface 210 of the pressure sensing core mechanism 200. The maximum length of the second inlet channel 112 along the expansion direction is greater than the maximum length of the first inlet channel 111 along the expansion direction, and the pressure buffer chamber 120 is disposed around the periphery of the second inlet channel 112. It can be understood that since the second inlet channel 112 is close to the pressure sensing surface 210, if the extrusion force of the urea crystal in the second inlet channel 112 is too large, the pressure sensing surface 210 of the pressure sensing core mechanism 200 will be damaged, while this problem does not need to be considered for the first inlet channel 111. Therefore, setting the maximum length of the second inlet channel 112 along the expansion direction to be larger can enable the urea crystal to have a larger accommodation space in the second inlet channel 112 and will not generate extrusion on the pressure sensing surface 210 when the amount of urea crystal is small. And setting the maximum length of the first inlet channel 111 along the expansion direction to be smaller can save the setting cost of the first inlet channel 111. In addition, since the pressure buffer chamber 120 only needs to be disposed around the second inlet channel 112 and does not need to be disposed around the first inlet channel 111, the material and process of the pressure buffer chamber 120 can be saved.

[0041] It should be noted that the volume of the pressure buffer chamber 120 can be set according to specific requirements during application, and no detailed limitation is provided here.

[0042] It should be noted that the distance between the pressure-sensitive surface 210 and the liquid outlet of the liquid inlet channel 110 can be set to a first threshold value to ensure that the urea solution will not extend out of the liquid outlet of the liquid inlet channel 110 during crystallization, pressing the pressure-sensitive surface 210 and causing the pressure-sensitive surface 210 to fail.

[0043] Optionally, in order to ensure the urea medium resistance performance and diesel resistance performance of the anti-expansion mechanism 100, a coating can be coated on the outside of the anti-expansion mechanism 100. For example, the coating material can be polytetrafluoroethylene, or perfluoroalkoxy resin, etc.

[0044] It should be noted that the pressure-sensitive core mechanism 200 can be any core mechanism capable of sensing pressure signals, such as a strain gauge type pressure-sensitive core mechanism, a ceramic piezoresistive pressure-sensitive core mechanism, or a piezoelectric ceramic pressure-sensitive core mechanism.

[0045] It should be noted that the signal conversion mechanism 300 can be any mechanism capable of converting a pressure signal into an electrical signal. For example, the signal conversion mechanism 300 can include circuit components, electrical connectors, and connectors. A micro control unit and an application-specific integrated circuit can be provided on the circuit components to convert the pressure signal generated by the pressure-sensitive core mechanism 200 into an analog signal or a digital signal corresponding to the pressure signal, and the electrical connector and the connector are connected to the circuit components to output the electrical signal (analog signal or digital signal) to the control system.

[0046] Optionally, as Figure 4 shown is a three-dimensional structure diagram provided by an embodiment of the present invention. A receiving groove 400 can be provided at the end of the urea pressure sensor. The receiving groove 400 can be used to receive a part of the electrical connector, such as a PIN pin, so that the electrical connector can be connected to the circuit components to output the electrical signal to the control system. A reinforcing rib 410 can be provided outside the receiving groove 400 to enhance the stability of the overall structure of the receiving groove 400. A connecting portion 500 can be provided between the receiving groove 400 and other parts of the urea pressure sensor. The diameter of the connecting portion 500 along the expansion direction of the anti-expansion mechanism 100 can be larger than the diameter of the receiving groove 400, so that the connecting portion 500 can play a role in stabilizing the structure of the receiving groove 400. A plurality of parallel grooves 510 arranged in sequence can be provided outside the connecting portion 500. Through these parallel grooves 510, a stress release effect can be achieved to avoid damaging the overall structure of the urea pressure sensor due to thermal expansion and contraction.

[0047] It can be understood that in order to ensure the reliability of the operation of the urea pressure sensor, the pressure range of the pressure-sensitive core mechanism 200 needs to meet the pressure range under the superposition of the normal operating pressure range of the urea pressure sensor and the ice expansion pressure of the urea medium.

[0048] In the embodiment of the present utility model, a pressure buffer chamber 120 is provided on the anti-expansion mechanism 100, and the pressure buffer chamber 120 is disposed around the periphery of the liquid inlet passage 110. Thus, even if the urea solution crystallizes in the liquid inlet passage 110 to generate extrusion pressure, due to the buffer space of the pressure buffer chamber 120, when being extruded by the extrusion pressure, the extrusion pressure can be eliminated as much as possible by extruding the buffer space, protecting the sensing sheet of the pressure core from being extruded.

[0049] In addition, since the pressure buffer chamber 120 is disposed around the periphery of the liquid inlet passage 110, when the liquid inlet passage 110 is extruded by urea crystallization, the extrusion pressure received by the entire periphery of the liquid inlet passage 110 can be eliminated. In the prior art, the urea pressure sensor only installs an anti-freezing plug at the position of the liquid inlet, so it can only offset the extrusion pressure of urea crystallization on the liquid inlet position. Obviously, the urea pressure sensor in the embodiment of the present utility model can eliminate a larger extrusion area of urea crystallization and has a better effect of offsetting the extrusion pressure of urea crystallization.

[0050] Furthermore, the anti-freezing plug in the prior art is only made of rubber material, so it only buffers the extrusion pressure of urea crystallization by using the elastic property of the anti-freezing plug itself, and the extrusion pressure it can offset is limited. In the embodiment of the present utility model, a pressure buffer chamber 120 is provided, and the extrusion pressure of urea crystallization is offset through the buffer space. Obviously, this can offset more extrusion pressure than using the property of the anti-freezing plug itself.

[0051] In summary, the urea pressure sensor provided in the embodiment of the present utility model can effectively offset the extrusion pressure generated by urea crystallization, so as to solve the problem that the sensing sheet of the pressure chip in the urea pressure sensor in the prior art is easily extruded and fails.

[0052] In an optional implementation manner, as Figure 2 and Figure 3 shown, the anti-expansion mechanism 100 has a first anti-expansion member 130 and a second anti-expansion member 140. The diameter of the second anti-expansion member 140 along the expansion direction is greater than the diameter of the first anti-expansion member 130 along the expansion direction, and the second anti-expansion member 140 is close to the pressure sensing core mechanism 200, and the first anti-expansion member 130 is far from the pressure sensing core mechanism 200.

[0053] It should be noted that the diameters of the first anti-expansion member 130 and the second anti-expansion member 140 along the expansion direction, as well as the lengths in the liquid inlet direction, can be set according to specific requirements during application, as long as it is ensured that the diameter of the second anti-expansion member 140 along the expansion direction is greater than that of the first anti-expansion member 130 along the expansion direction. The shapes of the first anti-expansion member 130 and the second anti-expansion member 140 can be set according to specific requirements during application, such as a cuboid or a cube, etc.

[0054] It can be understood that the first anti-expansion member 130 is away from the pressure-sensitive core mechanism 200, the second anti-expansion member 140 is close to the pressure-sensitive core mechanism 200, and the diameter of the second anti-expansion member 140 along the expansion direction is greater than that of the first anti-expansion member 130 along the expansion direction. Then, the second anti-expansion member 140 can make the overall structure of the anti-expansion mechanism 100 more stable. Especially when urea solution flows through the liquid inlet channel 110 and urea crystals are formed, the anti-expansion mechanism 100 will be subjected to a greater impact. Increasing the structural stability of the anti-expansion mechanism 100 can extend the service life of the anti-expansion mechanism 100.

[0055] In an alternative implementation, as Figure 2 and Figure 3 shown, the first anti-expansion member 130 is a cylinder, and the diameter direction of the cylinder is consistent with the expansion direction of the anti-expansion mechanism 100.

[0056] It can be understood that the first anti-expansion member 130 is a cylinder. Compared with the first anti-expansion member 130 being a structured body with edges and corners, when the extrusion force of urea crystals acts on the first anti-expansion member 130, the extrusion force can be more smoothly dispersed, reducing the stress concentration points, thereby extending the service life of the first anti-expansion member 130. Moreover, the curved or curved surface structure of the cylinder can more effectively absorb and consume the energy of the extrusion force when deforming. This structure can gradually bend in a larger area, extending the action path of the force, thereby converting it into other forms of energy and reducing the energy directly transmitted to the structure itself, so that it can withstand a greater extrusion force of urea crystals.

[0057] In an alternative implementation, the anti-expansion mechanism 100 is an elastic member.

[0058] It should be noted that in this implementation, the anti-expansion mechanism 100 is an elastic member, that is, the material of the anti-expansion mechanism 100 is an elastic material, such as the anti-expansion mechanism 100 is composed of an elastic material, etc.

[0059] It can be understood that the anti-expansion mechanism 100 is an elastic member, which can further buffer the extrusion force of urea crystallization through the buffering effect of the elastic member on the basis of buffering the extrusion force of urea crystallization through the pressure buffer chamber 120, so that the anti-expansion mechanism 100 can offset more extrusion forces generated by urea crystallization.

[0060] In an alternative implementation, the anti-expansion member further includes a support member (not shown in the figure), the support member is embedded inside the anti-expansion mechanism 100, and the support member is supported between opposite ends of the anti-expansion mechanism 100 along a first direction, and the first direction is perpendicular to the expansion direction of the anti-expansion mechanism 100.

[0061] It should be noted that the support member can be any device that can provide a supporting effect. For example, the support member can be a metal bracket.

[0062] Optionally, the support member can also be arranged along the expansion direction of the anti-expansion mechanism 100.

[0063] It can be understood that by providing the support member, the anti-expansion mechanism 100 can be prevented from deforming after being extruded for a long time, thereby extending the service life of the anti-expansion mechanism 100.

[0064] In an alternative implementation, as Figure 3 shown, the cross-section of the liquid inlet channel 110 is circular.

[0065] It can be understood that if the cross-section of the liquid inlet channel 110 is circular, the overall structure of the liquid inlet channel 110 is cylindrical.

[0066] It can be understood that the overall structure of the liquid inlet channel 110 is cylindrical. Compared with the liquid inlet channel 110 having an angular shape, when the extrusion force of urea crystallization acts on the sensor part adjacent to the liquid inlet channel 110, the extrusion force can be dispersed more smoothly, reducing the stress concentration point, thereby extending the service life of the sensor.

[0067] In an alternative implementation, as Figure 3 shown, the pressure buffer chamber 120 is an annular cavity.

[0068] It can be understood that the pressure buffer chamber 120 is an annular cavity. Compared with a cavity with sharp corners for the pressure buffer chamber 120, when the extrusion force of urea crystallization is transmitted to the annular cavity, the extrusion force can be dispersed more smoothly, reducing the stress concentration points, thereby prolonging the service life of the second anti-expansion member 140. Moreover, a curved or curved surface structure can more effectively absorb and consume the energy of the extrusion force when deforming. Such a structure can gradually bend in a larger area, extending the action path of the force, thereby converting it into other forms of energy and reducing the energy directly transmitted to the structure itself, so that it can withstand a greater extrusion force of urea crystallization.

[0069] Optionally, in order to form an annular cavity, the anti-expansion mechanism 100 can be processed into two parts during processing, and then the two parts of the anti-expansion mechanism 100 are combined together through a secondary vulcanization process.

[0070] In an alternative implementation, as Figure 1 and Figure 2 shown, the pressure-sensitive core mechanism 200 includes a diffused silicon oil-filled core 220.

[0071] It should be noted that existing urea pressure sensors mostly use ceramic cores as the pressure-sensitive cores. The pressure-sensitive diaphragm of the ceramic core is made of ceramic material and has good resistance to medium corrosion. However, the ceramic core also has inherent defects: the ceramic material cannot be sealed and fixed to the housing by welding and must use a sealing ring for sealing. Due to overpressure and medium corrosion problems, the sealing ring has problems with sealing failure. The diffused silicon oil-filled core 220 can also operate stably in a high-temperature, high-pressure, and corrosive medium environment for a long time. Therefore, in this implementation, the pressure-sensitive core in the pressure-sensitive core mechanism 200 is set as the diffused silicon oil-filled core 220, which can not only ensure that the urea pressure sensor works in a corrosive medium environment but also avoid a series of problems brought about when the pressure-sensitive core is made of ceramic material.

[0072] In an alternative implementation, as Figure 2 and Figure 3 shown, the pressure-sensitive core mechanism 200 further includes a first metal housing 230, and the first metal housing 230 is disposed around the periphery of the diffused silicon oil-filled core 220.

[0073] It should be noted that the material of the first metal housing 230 can be stainless steel material.

[0074] It can be understood that by disposing the first metal housing 230 around the periphery of the diffused silicon oil-filled core 220, it can ensure that the diffused silicon oil-filled core 220 is not damaged, thereby prolonging the service life of the diffused silicon oil-filled core 220.

[0075] In an alternative implementation, asFigures 1-4 As shown, the urea pressure sensor further includes a second metal housing 600. The second metal housing 600 is disposed outside the anti-expansion mechanism 100, the pressure sensing core mechanism 200, and the signal conversion mechanism 300, and the edge of the second metal housing 600 is hermetically welded to the edge of the first metal housing 230.

[0076] It should be noted that the material of the second metal housing 600 can be stainless steel.

[0077] It can be understood that in this implementation manner, the edge of the second metal housing 600 and the edge of the first metal housing 230 are the edge portions where the second metal housing 600 and the first metal housing 230 are joined. Since both the second metal housing 600 and the first metal housing 230 are made of metal materials, hermetically welding the edge of the second metal housing 600 and the edge of the first metal housing 230 can achieve high-reliability sealing.

[0078] Optionally, in order to further ensure the high reliability of the sealing, the second metal housing 600 and the first metal housing 230 can be integrally sealed first, and then the edges of the two are hermetically welded for the second time, so as to further increase the reliability of the sealing.

[0079] The technical solutions provided by the present utility model have been introduced in detail above. Specific examples are used in the present utility model to elaborate the principles and implementation manners of the present utility model. The descriptions of the above embodiments are only used to help understand the solutions and core ideas of the present utility model; at the same time, for those of ordinary skill in the art, according to the idea of the present utility model, there will be changes in the specific implementation manners and application scopes. In summary, the content of this specification should not be construed as a limitation to the present utility model.

[0080] Obviously, those skilled in the art can make various modifications and variations to the present utility model without departing from the spirit and scope of the present utility model. In this way, if these modifications and variations of the present utility model fall within the scope of the claims of the present utility model and their equivalent technologies, the present utility model also intends to include these modifications and variations.

Claims

1. A urea pressure sensor, characterized in that: include: An anti-expansion mechanism, wherein the anti-expansion mechanism is provided with a liquid inlet channel and a pressure buffer chamber, and the pressure buffer chamber is arranged around the periphery of the liquid inlet channel; A pressure-sensitive core mechanism, wherein the pressure-sensitive core mechanism has a pressure-sensitive surface, and the pressure-sensitive surface is located on a side of the pressure-sensitive core mechanism close to the liquid outlet of the liquid inlet channel; The signal conversion mechanism is electrically connected to the pressure-sensitive core mechanism and is used for converting the pressure signal detected by the pressure-sensitive core mechanism into an electrical signal.

2. The urea pressure sensor according to claim 1, characterized in that: The anti-expansion mechanism has a first anti-expansion component and a second anti-expansion component, the diameter of the second anti-expansion component along the expansion direction is larger than the diameter of the first anti-expansion component along the expansion direction, and the second anti-expansion component is close to the pressure-sensitive core mechanism, and the first anti-expansion component is far away from the pressure-sensitive core mechanism.

3. The urea pressure sensor according to claim 2, characterized in that: The first anti-expansion member is a cylinder, and the diameter direction of the cylinder is consistent with the expansion direction of the anti-expansion mechanism.

4. The urea pressure sensor according to claim 1, characterized in that: The anti-expansion mechanism is an elastic member.

5. The urea pressure sensor according to claim 1, characterized in that: The anti-expansion mechanism further comprises a support member, which is embedded in the anti-expansion mechanism and supported between opposite ends of the anti-expansion mechanism along a first direction, wherein the first direction is perpendicular to the expansion direction of the anti-expansion mechanism.

6. The urea pressure sensor according to claim 3, characterized in that: The cross section of the liquid inlet channel is circular.

7. The urea pressure sensor according to claim 6, characterized in that: The pressure buffer chamber is an annular cavity.

8. The urea pressure sensor according to claim 1, characterized in that: The pressure-sensitive core mechanism comprises a diffused silicone oil-filled core.

9. The urea pressure sensor according to claim 8, characterized in that: The pressure-sensitive core structure further comprises a first metal shell, which is arranged around the periphery of the diffused silicon oil-filled core.

10. The urea pressure sensor according to claim 9, characterized in that: It also includes a second metal shell, which is arranged on the outside of the anti-expansion mechanism, the pressure-sensitive core mechanism and the signal conversion mechanism, and the edge of the second metal shell is sealed and welded to the edge of the first metal shell.

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