CN206609558U - Micro- molten technology urea pressure sensor - Google Patents

Abstract

The utility model discloses a urea pressure sensor with micro-melting technology, which comprises a nylon shell, an amplifying circuit board, a bonding circuit board, a silicon strain gauge, a stainless steel diaphragm, an epoxy resin glue layer, a cable; the end of the stainless steel diaphragm Nested in the nylon shell; there is an epoxy resin glue layer between the stainless steel diaphragm and the nylon shell; the front end of the stainless steel diaphragm is provided with a pressure port; the pressure port is provided with an EPDM soft hose; the front end of the EPDM soft hose There is a stainless steel damping plug; a silicon strain gauge is sintered on the back of the end of the stainless steel diaphragm; the silicon strain gauge is connected to the bonding circuit board through the bonding wire; the bonding circuit board is connected to the amplifying circuit board; the amplifying circuit board is connected to the cable; The end of the cable extends to the outside of the nylon shell; there is no silicone oil filled inside, no welds, no seals, and no hidden dangers of leakage. It can improve the reliability of the urea pressure sensor, eliminate hidden dangers of leakage, and improve product life. Not damaged by ice crystallization.

Description

Microfusion technology urea pressure sensor

technical field

The utility model relates to the field of pressure measuring devices for urea pumps, in particular to a urea pressure sensor with micro-melting technology.

Background technique

The urea pressure sensor is a urea pump pressure measurement device used in the SCR system of a diesel truck. It is installed on the SCR system to measure the pressure of the urea solution. According to the pressure measurement, it controls the work of the urea pump and diagnoses whether the urea nozzle is working normally. . The nozzle sprays urea solution for catalytic reduction treatment of automobile exhaust.

The existing technology in China usually adopts the technology of diffusion silicon oil filling and the technology of ceramic pressure sensor.

Diffused silicon oil-filled technology uses a diffused silicon pressure sensor to isolate the measurement medium through a corrugated diaphragm. The pressure of the medium is first transmitted to the corrugated diaphragm, and then the pressure is transmitted to the diffused silicon through the silicone oil filled between the corrugated diaphragm and the silicon chip. film; the overload capacity of diffused silicon oil-filled products is determined by the silicon film, which is usually twice the rated pressure. , Overload, urea freezing and other working conditions, the product is easily damaged.

The ceramic pressure sensor technology is to press the ceramic core into the plastic shell, and the ceramic material and the plastic part are sealed by an O-ring, which increases the hidden danger of leakage. The ceramic material is easy to crack under low temperature conditions and urea freezing conditions. In order to cause failure, the overload pressure of ceramic pressure sensors is usually twice as high. The output sensitivity of the ceramic pressure sensor is low, which requires a high circuit magnification. At the same time, the product is large in size, and the installation position and space requirements are high.

In the automotive SCR system, the usual failure modes of the urea pressure sensor are overload, diaphragm damage, etc. The failure of the pressure sensor directly leads to the failure of the entire SCR system.

Utility model content

The purpose of the utility model is to provide a micro-melting technology urea pressure sensor with simple structure, reasonable design and convenient use in view of the defects and deficiencies of the prior art.

In order to achieve the above object, the technical scheme adopted by the utility model is: it comprises a nylon shell, an amplifying circuit board, a bonding circuit board, a silicon strain gauge, a stainless steel diaphragm, an epoxy resin adhesive layer, and a cable; the stainless steel membrane The end of the film is nested in the nylon shell; the epoxy resin glue layer is potted between the stainless steel diaphragm and the nylon shell; the front end of the stainless steel diaphragm is provided with a pressure port; The front end of the hose is provided with a stainless steel damping plug; the back of the end of the stainless steel diaphragm is sintered with a silicon strain gauge by glass sintering process; the silicon strain gauge is connected to the bonding circuit board through the bonding wire; the bonding circuit board is connected to the amplifying circuit board; The amplifying circuit board is connected with the cable; the end of the cable extends to the outside of the nylon shell;

Preferably, the stainless steel diaphragm is an integral rigid stainless steel diaphragm;

Preferably, the pressure introduction port is a tapered pressure introduction port;

Preferably, an O-ring is provided outside the front end of the stainless steel diaphragm;

Preferably, an overvoltage protection element is provided on the bonding circuit board;

Preferably, the terminal of the cable is provided with three wires, and the three wires are positive power line, negative power line, and signal output line respectively.

After adopting the above structure, the beneficial effects of the utility model are: the urea pressure sensor with the micro-melting technology described in the utility model has no silicone oil filled inside, no welding seam, no seal, and no hidden danger of leakage, which can improve the reliability of the urea pressure sensor It has the advantages of simple structure, reasonable setting, and low production cost.

Description of drawings

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 accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description These are only some embodiments of the utility model, and those skilled in the art can also obtain other drawings according to these drawings without any creative effort.

Fig. 1 is the structural representation of the utility model;

Fig. 2 is the top view of the utility model;

Fig. 3 is a side view of the utility model.

Explanation of reference signs:

1. Three wires; 2. Cable; 3. Nylon shell; 4. Amplifying circuit board; 5. Bonding circuit board; 6. Silicon strain gauge; 7. Stainless steel diaphragm; 8. Epoxy resin layer; 9. O-shaped sealing ring; 10. Pressure port; 11. EPDM soft hose; 12. Stainless steel damping plug.

detailed description

Below in conjunction with accompanying drawing, the utility model is described further.

Referring to Fig. 1-3, it includes a nylon shell 3, an amplifying circuit board 4, a bonding circuit board 5, a silicon strain gauge 6, a stainless steel diaphragm 7, an epoxy resin adhesive layer 8, and a cable 2; the stainless steel The end of the diaphragm 7 is nested in the nylon casing 3; the epoxy resin adhesive layer 8 is potted between the stainless steel diaphragm 7 and the nylon casing 3; the front end of the stainless steel diaphragm 7 is provided with a pressure port 10; the pressure port 10 There is an EPDM soft hose 11 inside; the front end of the EPDM soft hose 11 is provided with a stainless steel damping plug 12; the back of the end of the stainless steel diaphragm 7 is sintered with a glass sintering process and a silicon strain gauge 6 is sintered; The circuit board 5 is connected; the bonding circuit board 5 is connected with the amplifying circuit board 4; the amplifying circuit board 4 is connected with the cable 2; the end of the cable 2 extends to the outside of the nylon shell 3;

Preferably, the stainless steel diaphragm 7 is an integral rigid stainless steel diaphragm;

Preferably, the pressure introduction port 10 is a tapered pressure introduction port;

Preferably, an O-ring seal 9 is provided on the outside of the front end of the stainless steel diaphragm 7;

Preferably, the bonding circuit board 5 is provided with an overvoltage protection element;

Preferably, the cable 2 is provided with three wires 1 at the terminal, and the three wires 1 are the positive power line, the negative power line, and the signal output line respectively.

In this specific embodiment, the stainless steel diaphragm 7 is an integrated rigid stainless steel diaphragm, and the pressure introduction port of the stainless steel diaphragm 7 is designed as a tapered hole, and the solid after the urea solution freezes or crystallizes will gradually move to the port, avoiding the The stainless steel diaphragm 7 is damaged; the stainless steel damping plug 12 and the EPDM soft hose 11 in the pressure introduction hole constitute the anti-crystallization and freezing protection function of the urea pressure sensor, which ensures that the urea pressure sensor is not damaged in the case of low-temperature freezing and crystallization;

The protection principle of icing and crystallization is: the front end is welded with a stainless steel damping plug 12 to block the urea that freezes and expands in the pipeline. Inside the damping plug, the EPDM soft hose 11 can absorb the volume of the internal urea that freezes and expands, thereby maintaining the pressure of the urea. The sensor will not be damaged due to the overload of the urea freezing expansion extrusion diaphragm.

The material of the stainless steel diaphragm 7 can be 316, 316L, 304, 17-4, which is resistant to impact and is not easily damaged. It can be verified whether the output of the pressure sensor changes with the pressure with a hard object against the diaphragm; the overload capacity of the urea pressure sensor is completely determined by the stainless steel diaphragm. The thickness of the diaphragm 7 is determined by increasing the thickness of the stainless steel diaphragm 7, which can greatly improve the overload resistance of the pressure sensor;

The silicon strain gauge 6 is sintered on the back of the stainless steel diaphragm 7 through glass, and the silicon strain gauge 6 leads the signal to the bonding circuit board 5 through the state wire, and the formed Wheatstone bridge produces a millivolt output proportional to the pressure. The silicon strain gauge 6 is used, and the signal output sensitivity is very high. In the case of 5V power supply, it can output 100-200mV;

The overvoltage protection element on the bonding circuit board 5 can ensure that the urea pressure sensor will not be damaged by overvoltage and surge;

The amplifying circuit board 4 adopts the sensor signal conditioning chip NSA2300 to amplify the signal of the sensor and perform temperature compensation to ensure that the urea pressure sensor can work normally in a wide temperature range and minimize the error caused by temperature changes;

The cable 2 outputs the amplified signal, and the terminal has three wires 1, namely the power supply wire (usually 5V), the power ground wire, and the pressure signal output wire (usually 0.5V to 4.5V output);

The nylon shell 3 can also be a metal shell or a plastic shell.

The urea pressure sensor with micro-melting technology described in the utility model maintains the conventional installation method of the urea pressure sensor in appearance, that is, the middle stainless steel part adopts the method of side sealing, and the two sides adopt the method of pressing with two screws.

This specific embodiment adopts glass micro-melting technology, or called silicon strain technology. The main structure is an integrally processed stainless steel diaphragm. The measuring medium is separated from the electronic cavity by the stainless steel diaphragm. The technology of sintered silicon strain gauge, when the measuring medium is under pressure, the diaphragm will be slightly deformed, causing the resistance value of the silicon strain gauge sintered on the back to change, and the bridge formed by the silicon strain gauge will generate output under the condition of power supply. The sensor signal conditioning chip amplifies the output signal and performs temperature compensation, and finally outputs a voltage output that is linearly related to the pressure.

The above is only used to illustrate the technical solution of the utility model without limitation, other modifications or equivalent replacements made by those skilled in the art to the technical solution of the utility model, as long as they do not depart from the spirit and scope of the technical solution of the utility model , should be covered in the scope of the claims of the present utility model.

Claims (6)

1. micro-fusion technology urea pressure sensor, it is characterized in that it comprises nylon casing, amplifying circuit board, bonding circuit board, silicon strain gauge, stainless steel diaphragm, epoxy resin adhesive layer, cable wire; Described stainless steel diaphragm The end is nested in the nylon shell; the stainless steel diaphragm and the nylon shell are potted with an epoxy resin glue layer; the front end of the stainless steel diaphragm is provided with a pressure port; the pressure port is provided with an EPDM soft hose; The front end is equipped with a stainless steel damping plug; the back of the end of the stainless steel diaphragm is sintered with a silicon strain gauge using a glass sintering process; the silicon strain gauge is connected to the bonding circuit board through the bonding wire; the bonding circuit board is connected to the amplifying circuit board; the amplifying circuit The plate is attached to the cable; the end of the cable extends to the outside of the nylon housing. 2. The urea pressure sensor according to claim 1, characterized in that the stainless steel diaphragm is an integral rigid stainless steel diaphragm. 3. The microfusion technology urea pressure sensor according to claim 1 or 2, characterized in that the pressure introduction port is a tapered pressure introduction port. 4. The urea pressure sensor according to claim 1 or 2, characterized in that an O-ring is provided outside the front end of the stainless steel diaphragm. 5. The urea pressure sensor with micro-fusion technology according to claim 1, characterized in that an overvoltage protection element is provided on the bonding circuit board. 6. The micro-fusion technology urea pressure sensor according to claim 1, characterized in that there are three wires at the terminal of the cable, and the three wires are respectively the positive line of the power supply, the negative line of the power supply, and the signal output line.