Anti-freezing structure of urea pressure sensor

Abstract

The utility model relates to the technical field of urea pressure sensors, in particular to an anti-freezing structure of a urea pressure sensor, which comprises a urea pressure sensor shell, an elastic body is clamped and assembled in the urea pressure sensor shell, a chute is arranged in the elastic body, a circuit module is further mounted in the urea pressure sensor shell, and the circuit module is connected with the urea pressure sensor shell. The circuit module is electrically connected with the urea pressure sensor shell through a thick aluminum wire in a bonding mode, and an oil filling core body is further arranged in the urea pressure sensor shell. According to the anti-freezing structure of the urea pressure sensor, the elastomer with relatively high compressibility is adopted, so that the urea solution can be better absorbed, the expansion pressure of the urea solution at the core body is further reduced, and the pressure sensing element can be effectively prevented from being damaged by urea crystal expansion force, so that the low-temperature adaptive capacity of the urea pressure sensor can be enhanced; therefore, the urea pressure sensor is good in reliability and long in service life in an extremely low-temperature environment, and the actual use requirements are better met.

Description

Technical Field

[0001] The utility model relates to the technical field of urea pressure sensors, and specifically relates to an anti-freezing structure for a urea pressure sensor. Background Technique

[0002] A urea pressure sensor is a sensor used in the SCR urea injection system for the post-treatment of diesel engine exhaust, which performs urea pressure detection to assist in determining the urea injection amount. In a system that uses selective catalytic reduction (SCR) technology to reduce nitrogen oxide (NOx) emissions, urea solution (also known as diesel exhaust fluid or DEF) is sprayed into the exhaust stream, and with the help of a catalyst, harmful nitrogen oxides are converted into harmless nitrogen and water vapor. Due to the increasingly serious air pollution and the increasing requirements for environmental protection, higher requirements are put forward for diesel engine exhaust emissions. The particulate matter (PMD) 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 standard, generally no measures are taken from the structure of the engine itself. Usually, post-treatment of the exhaust 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 the 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 generally located in the urea injection pump or the urea delivery pipeline, and it provides real-time pressure information to the vehicle's electronic control unit (ECU) to ensure that urea can be sprayed into the exhaust system at the correct pressure and flow rate.

[0003] However, 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 of the urea pressure sensor. The residual urea liquid will form urea crystals at low temperatures. Since the ceramic core is directly installed in the metal shell, the urea crystals will squeeze the sensing sheet of the ceramic core, greatly reducing the service life of the most critical ceramic core in the urea pressure sensor, and even causing the sensing sheet to be cracked and the sensor to fail directly.

[0004] Therefore, the problem of anti-freezing treatment for the urea pressure sensor and extending its service life needs to be solved urgently. Content of the Utility Model

[0005] The purpose of the present utility model is to provide an anti-freezing structure for a urea pressure sensor, so as to solve the problem proposed in the above-mentioned background technology that urea crystallization will form in the urea pressure sensor at low temperatures in the current market. The urea crystallization will squeeze the sensing sheet of the ceramic core, greatly reducing the service life of the most critical ceramic core in the urea pressure sensor, and even causing the sensing sheet to be cracked and the sensor to directly fail.

[0006] To achieve the above purpose, the present utility model provides the following technical solutions: an anti-freezing structure for a urea pressure sensor, including a urea pressure sensor housing, an elastomer is snap-fitted and assembled inside the urea pressure sensor housing, and an inclined groove is formed inside the elastomer. A circuit module is also installed inside the urea pressure sensor housing, and a self-tapping screw is fixedly penetrated between the circuit module and the urea pressure sensor housing, and the circuit module and the urea pressure sensor housing are electrically connected by bonding with a thick aluminum wire. An oil-filled core is also provided inside the urea pressure sensor housing, and the oil-filled core is soldered to the circuit module, and a sealing ring is tightly sleeved on the side of the oil-filled core.

[0007] Preferably, a rear cover is further provided on the back of the urea pressure sensor housing, and the rear cover is laser welded and fixed to the urea pressure sensor housing.

[0008] Preferably, a Venturi tube column is integrally provided on one side of the urea pressure sensor housing, and a Venturi tube hole is provided inside the Venturi tube column.

[0009] Preferably, a liquid inlet pipe opening is provided at the thick-diameter end of the Venturi tube hole, and the thick-diameter end of the Venturi tube hole is communicated with the inclined groove.

[0010] Preferably, a corrugated diaphragm is installed between the elastomer and the oil-filled core.

[0011] Preferably, the outer ring of the sealing ring is closely attached to the urea pressure sensor housing, and the sealing ring is also provided at the outer side of the elastomer.

[0012] Compared with the prior art, the beneficial effects of the present utility model are as follows:

[0013] 1. The anti-freezing structure of the urea pressure sensor adopts an elastomer with relatively large compressibility, which can better absorb urea solution, thereby reducing the expansion pressure of the urea solution at the core, effectively avoiding damage to the pressure sensing element caused by the expansion force of urea crystallization, enhancing the low-temperature adaptability of the urea pressure sensor, making the urea pressure sensor reliable and having a long service life in an extremely low-temperature environment, and better meeting the actual use requirements.

[0014] 2. The anti-freezing structure of the urea pressure sensor adopts an inclined groove structure inside the elastomer, which can better make the urea solution flow out and reduce the expansion pressure of the urea solution at the core.

[0015] 3. The anti-freezing structure of the urea pressure sensor changes the pressure-sensitive ceramic core to an oil-filled core, which not only improves the deficiency of the ceramic core being prone to brittle fracture, but also the oil-filled core has the advantages of anti-freezing and anti-corrosion, improving the accuracy of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the internal structure of an anti-freezing structure of a urea pressure sensor of the present invention;

[0017] Figure 2 It is a schematic diagram of the external structure of an anti-freezing structure of a urea pressure sensor of the present invention;

[0018] Figure 3 It is an axonometric view of an anti-freezing structure of a urea pressure sensor of the present invention;

[0019] Figure 4 It is a schematic diagram of the structure in which the venturi tube hole of an anti-freezing structure of a urea pressure sensor of the present invention communicates with the inclined groove.

[0020] In the figure: 1. Urea pressure sensor housing; 101. Venturi tube hole; 102. Venturi tube column; 103. Liquid inlet pipe orifice; 2. Elastomer; 201. Inclined groove; 3. Sealing ring; 4. Circuit module; 5. Corrugated diaphragm; 6. Rear cover; 7. Oil-filled core; 8. Self-tapping screw. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0021] 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. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0022] Please refer to Figures 1-4, the present utility model provides a technical solution: an anti-freezing structure for a urea pressure sensor, including a urea pressure sensor housing 1, an elastomer 2 is snap-fitted and assembled inside the urea pressure sensor housing 1, and an inclined groove 201 is formed inside the elastomer 2. One side of the urea pressure sensor housing 1 is integrally provided with a Venturi tube column 102, and a Venturi tube hole 101 is arranged inside the Venturi tube column 102. This structure of the Venturi tube hole 101 consists of a converging tube, a throat tube, and a diverging tube. The design of the Venturi tube has a certain basis in fluid mechanics. When air flow or liquid flow passes through, the fluid changes from thick to thin, and the pressure is relatively low near the upper port on the leeward side, forming a relatively vacuum area, thereby generating an adsorption effect, which can remove urea crystals, help clear the crystals, and achieve the function of discharging trapped air. The thick-diameter end of the Venturi tube hole 101 is provided with a liquid inlet pipe 103, and the thick-diameter end of the Venturi tube hole 101 is communicated with the inclined groove 201. In this structure, under the structure of the Venturi tube hole 101, the urea fluid in the oil-filled core 7 changes from static to flowing. The flowing liquid can play a role in discharging trapped air and helping to clear. When there is no liquid flow, the air pressure difference can be used to remove crystals. The inclined groove 201 can better allow the urea solution to flow out, reducing the expansion pressure of the urea solution at the oil-filled core 7. The traditional pressure-sensitive ceramic core is changed to an oil-filled core 7, which not only improves the problem of easy brittleness of the ceramic core, but also has anti-freezing and anti-corrosion functions, improving the accuracy of the product. A circuit module 4 is also installed inside the urea pressure sensor housing 1, and a self-tapping screw 8 is fixedly penetrated between the circuit module 4 and the urea pressure sensor housing 1. And the circuit module 4 and the urea pressure sensor housing 1 are electrically connected by bonding with a thick aluminum wire. An oil-filled core 7 is also provided inside the urea pressure sensor housing 1. A corrugated diaphragm 5 is installed between the elastomer 2 and the oil-filled core 7. This structure of the corrugated diaphragm 5 is used to convert the pressure change in the urea system into a measurable physical displacement or electrical signal. And the oil-filled core 7 and the circuit module 4 are connected by soldering. And a sealing ring 3 is tightly sleeved on the side of the oil-filled core 7. The outer ring of the sealing ring 3 closely adheres to the urea pressure sensor housing 1, and the sealing ring 3 is also arranged at the outer side part of the elastomer 2. This structure can perform a fastening installation process for the oil-filled core 7 through the sealing ring 3, and at the same time, the sealing ring 3 provides sealing tightness. A rear cover 6 is also provided on the back of the urea pressure sensor housing 1, and the rear cover 6 and the urea pressure sensor housing 1 are fixed by laser welding. This structure can perform a sealing protection process for the installation parts of the circuit module 4 and the oil-filled core 7 through the rear cover 6.

[0023] Working principle: When using the anti-freezing structure of the urea pressure sensor, first, the elastomer 2 is assembled into the urea pressure sensor housing 1. The elastomer 2 has a relatively large compressibility, which can better absorb the urea solution, thereby reducing the expansion pressure of the urea solution at the core. The inclined groove 201 of the elastomer 2 corresponds to the thick diameter of the Venturi tube hole 101, which can better allow the urea solution to flow out and reduce the expansion pressure of the urea solution at the core. The thick diameter of the Venturi tube hole 101 is set as the liquid inlet 103. Through the special design of the Venturi tube hole 101, when the air flow passes through, the pressure near the upper port of the leeward side of the Venturi tube hole 101 is relatively low, forming a relatively vacuum area, generating an adsorption effect, which can achieve the functions of removing urea crystallization, helping to empty, and discharging trapped air. The Venturi tube column 102 is integrally formed with the urea pressure sensor housing 1, making the structure of the Venturi tube hole 101 and the elastomer 2 stable. Then, the corrugated diaphragm 5 is assembled. After the oil-filled core 7 is installed with the sealing ring 3, it is assembled into the urea pressure sensor housing 1. The oil-filled core 7 has the functions of anti-freezing and anti-corrosion, improving the accuracy of the product and extending the service life. The sealing ring 3 provides sealing tightness. Then, the circuit module 4 is assembled into the urea pressure sensor housing 1. The circuit module 4 and the urea pressure sensor housing 1 are fixed by self-tapping screws 8. The oil-filled core 7 and the circuit module 4 are connected by soldering. The circuit module 4 and the urea pressure sensor housing 1 are bonded by thick aluminum wires. Finally, the rear cover 6 is fixed by laser welding to complete a series of operations.

[0024] Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A urea pressure sensor anti-freezing structure, comprising a urea pressure sensor housing (1), characterized in that: An elastic body (2) is snap-fitted into the housing (1) of the urea pressure sensor, and an inclined groove (201) is provided in the elastic body (2). A circuit module (4) is also installed in the housing (1) of the urea pressure sensor, and a self-tapping screw (8) is passed through and fixed between the circuit module (4) and the housing (1) of the urea pressure sensor, and the circuit module (4) and the housing (1) of the urea pressure sensor are electrically connected by bonding with a thick aluminum wire. An oil-filled core (7) is also provided in the housing (1) of the urea pressure sensor, and the oil-filled core (7) and the circuit module (4) are connected by soldering, and a sealing ring (3) is fastened and sleeved on the side of the oil-filled core (7).

2. The anti-freezing structure of a urea pressure sensor according to claim 1, characterized in that: A rear cover (6) is also provided on the back of the urea pressure sensor housing (1), and the rear cover (6) is fixed to the urea pressure sensor housing (1) by laser welding.

3. The anti-freezing structure of a urea pressure sensor according to claim 1, characterized in that: A venturi tube column (102) is integrally provided on one side of the urea pressure sensor housing (1), and a venturi tube hole (101) is provided in the venturi tube column (102).

4. The anti-freezing structure of a urea pressure sensor according to claim 3, characterized in that: A liquid inlet (103) is provided at one end of the venturi tube hole (101) with a thick tube diameter, and the one end of the venturi tube hole (101) with a thick tube diameter is connected to the inclined groove (201).

5. The anti-freezing structure of a urea pressure sensor according to claim 1, characterized in that: A corrugated diaphragm (5) is installed between the elastic body (2) and the oil-filled core (7).

6. The anti-freezing structure of a urea pressure sensor according to claim 1, characterized in that: The outer ring of the sealing ring (3) is in close contact with the housing (1) of the urea pressure sensor, and the sealing ring (3) is also arranged on the outer side of the elastic body (2).

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