CN111289167A - A sensor for measuring the internal pressure of a tank for storing volatile liquids - Google Patents

Abstract

The invention relates to a sensor in the field of sensors for measuring the internal pressure of a tank body for storing volatile liquids. One end of the plug-in terminal is provided with a plug-in port, a plug-in terminal is embedded in the shell, one end of the plug-in terminal extends into the plug-in port, the other end of the plug-in terminal is electrically connected with the PCB board, and the upper side of the shell is provided with an upper cover covering the cavity , the lower side of the shell is provided with a guide post for connecting and installing with the tank, the center of the guide post is provided with a vent hole, the PCB board is provided with a pressure hole corresponding to the vent hole, and the underside of the pressure hole on the PCB board is connected to the shell A sealed connection between them; the pressure measuring surface of the air vent pressure sensor assembly, and the opposite side of the pressure measuring surface of the pressure sensor assembly is connected to the atmosphere. The device is easy to achieve sealing, can be conveniently installed on the fuel tank of the car or the accessories of the fuel tank, is resistant to gasoline vapor corrosion, and has good resistance to HC penetration.

Description

A sensor for measuring the internal pressure of a tank for storing volatile liquids

technical field

The invention relates to a sensor for measuring the internal pressure of a volatile liquid storage device at normal temperature, especially the internal pressure of an automobile fuel evaporation system.

Background technique

Vehicles with internal combustion engines include fuel tanks that store liquid fuels as well as volatile liquid fuels such as gasoline, methanol, or other fuels. These fuels are easily evaporated into fuel vapors under the influence of temperature (including direct solar radiation, ground thermal energy radiation, high temperature conduction of oil pumps, and oil return temperature heating of oil return pipes). Fuel vapors are almost always present whether the vehicle is moving or stopped. If these fuel vapors are directly discharged into the atmosphere, it will cause serious environmental pollution on the one hand, and great economic losses on the other hand. Therefore, it is necessary to have a system in the vehicle to collect and utilize these fuel vapors, which is called "evaporative emission management system". The evaporative emission management system of traditional low-pressure fuel tank includes fuel tank, carbon canister, pressure sensor, carbon canister desorption valve, etc.; the evaporative emission management system of plug-in hybrid high-pressure fuel tank includes fuel tank, carbon canister, pressure sensor, carbon canister Tank Desorption Valves, Tank Isolation Valves, Leak Detection Modules, etc.

US Patent No. 5,267,470 discloses a technical solution of integrating a pressure sensor with a fuel tank overturn valve to prevent fuel leakage after the vehicle is overturned. However, there are some shortcomings in this method, such as the integrated product installation method is relatively simple, and the assembly process requirements of the product are greatly improved after the integrated fuel tank flip valve.

In the US patent US6131445, a new installation solution is proposed. The pressure sensor is fixed to the fuel tank flange through the structural design of the inverted bayonet and the sealing ring. This design also limits the installation method of the pressure sensor. At the same time, the installation method is easy to break the buckle during installation, and problems may occur when the pressure is large. In addition, the patent discloses that the internal unit of the pressure sensor is glued to the housing. In order to avoid the glue blocking the ventilation holes, the process requirements are higher. On the other hand, this bonding technique can be risky given the high-pressure fuel tank of a plug-in hybrid.

In the prior art, it is very difficult to directly install a pressure sensor on the fuel tank due to the limitation of the fuel tank material. The traditional solution is to mount the pressure sensor to the oil pump flange, filler pipe or tank rollover valve. These installations are subject to the influence of the structure and wiring of the fuel tank, and require higher system layout. The current pressure sensor is generally used in the leakage detection scheme of traditional internal combustion engines, and the pressure detection range is relatively low, generally -3.75kPa~1.25kPa. For the application of new energy vehicles, such as plug-in hybrid vehicles, the pressure detection range is expanded to -2.5Psi~5.5Psi. The increase in pressure level not only increases the pressure resistance level of the fuel tank, but also increases the pressure resistance level of the pressure sensor. Also correspondingly greatly improved. On the one hand, the fixed strength requirements of the internal chip of the pressure sensor are improved, and on the other hand, the sealing pressure resistance level of the pressure sensor installed on the carrier is also greatly improved.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a sensor for measuring the internal pressure of a tank for storing volatile liquids, so that it can be easily installed on the fuel tank of an automobile or on the accessories (pipeline, carbon canister) of the fuel tank, and is resistant to gasoline vapor corrosion, and at the same time resists HC (hydrocarbon) permeability is good.

The purpose of the present invention is to achieve this: a sensor for measuring the internal pressure of a tank for storing volatile liquids, including a housing, the housing is provided with a cavity, a PCB board is installed in the cavity, and the PCB board is provided with There is a pressure sensor assembly, one end of the casing is provided with a plug-in port, a plug-in terminal is embedded in the casing, one end of the plug-in terminal extends into the plug-in port, the other end of the plug-in terminal is electrically connected with the PCB board, and the upper side of the casing is provided with a plug-in terminal. The upper cover that covers the cavity, the lower side of the casing is provided with a guide post for connection and installation with the tank body, a sealing sleeve is installed on the guide post, the center of the guide post is provided with a ventilation hole, and the PCB board is provided with a corresponding ventilation hole. Pressure measuring hole, the lower side of the pressure measuring hole on the PCB board is sealed with the casing; the vent hole is connected to the pressure measuring surface of the pressure sensor assembly through the pressure measuring hole, and the pressure measuring surface of the pressure sensor assembly is opposite to each other. The other side is open to the atmosphere.

When the invention works, it is connected with the tank body storing volatile liquid through the guide post, and connected with the electric control unit through the plug port, so that the pressure signal in the tank body can be transmitted to the electric control unit. Since the PCB board and the pressure sensor assembly are arranged in the cavity, they have a good sealing effect, and the PCB board has sufficient strength to withstand higher pressure, so that the pressure measurement range of the device is larger. Compared with the prior art, the beneficial effect of the present invention is that the device is easy to install and fix, easy to achieve sealing, can be easily installed on the fuel tank of the automobile or the accessories of the fuel tank (pipeline, carbon canister), and is resistant to gasoline vapor corrosion, and at the same time resists the corrosion of gasoline vapor. HC (hydrocarbon) permeability is good.

As a further improvement of the present invention, an O-ring is provided between the lower side of the pressure measuring hole on the PCB board and the housing, and the PCB board and the housing are riveted by hot riveting posts; the periphery of the upper cover is It is sealed and bonded with the casing by a sealant. The riveted connection of the hot riveting post can provide the appropriate compression force so that the O-ring can achieve a good seal.

As a further improvement of the present invention, the upper side of the upper cover is provided with a dust-proof connection seat that protrudes upward, the dust-proof connection seat is installed with a dust-proof cover, and the center of the dust-proof connection seat is provided with a ventilation hole penetrating the upper cover, A micro-channel connected to the atmosphere is left between the dust-proof cover and the dust-proof connecting seat. The structure ensures that the sensor has a good dustproof effect and ensures the stability and reliability of pressure detection.

As a further improvement of the present invention, the inner side of the upper cover is provided with a waterproof and breathable membrane corresponding to the ventilation holes. The waterproof and breathable membrane can prevent water from entering the cavity and prevent short circuit or rust of the PCB board while ensuring ventilation.

As a further improvement of the present invention, the pressure sensor assembly includes a ceramic substrate disposed above the PCB board, the ceramic substrate is provided with a sensor unit plastic-encapsulated casing, and the sensor unit plastic-encapsulated casing is fixed and transmitted by solid crystal glue. The sensing element and the conditioning chip, the upper side of the sensing element is connected to the atmosphere, and the lower side of the sensing element is connected to the vent hole to form a differential pressure sensor, and the electrical connection between the conditioning chip and the sensing element is used to convert the differential pressure signal into a voltage signal. connect. In this scheme, a layer of ceramic substrate substrate is added between the sensor element and the PCB, and the pressure sensing chip and the substrate are clearly separated; this structure can eliminate the influence of mechanical stress on the output accuracy of the product, and avoid the stress acting on the pressure. On the sensing element, the accuracy of the sensor is effectively improved. The sensing element and the conditioning circuit are encapsulated in a plastic casing to form a modular assembly. Since the plastic encapsulated casing has good rigidity, surface finish and resistance to HC molecular penetration, the end face of the assembly can be directly assembled with the sealing ring, and good rigidity can be avoided. The stress generated by compressing the sealing ring affects the internal sensing element, and the smooth end face and the sealing ring can form a good seal.

As a further improvement of the present invention, the guide post has a barb structure to prevent the sealing sleeve from slipping off.

As a further improvement of the present invention, the housing is made of nylon material by injection molding; the O-ring and the sealing sleeve are made of fluorine-containing rubber material. The anti-HC molecular penetration performance of the material can effectively improve the HC emission performance of the sensor assembly.

Description of drawings

Figure 1 is a schematic structural diagram of the present invention.

FIG. 2 is a partial enlarged view of the pressure sensor assembly.

Figure 3 is a partial enlarged view of the upper cover and the dust cover.

FIG. 4 is a state diagram of the present invention.

Among them, 1 plug interface, 2 plug terminals, 3 shell, 4 sealant, 5 upper cover, 6 dust cover, 7 ventilation hole, 8 dustproof connector, 9 waterproof and breathable membrane, 10 pressure sensor assembly, 1001 transmission Sensor element, 1002 conditioning chip, 1003 solid crystal glue, 1004 sensor unit plastic casing, 1005 ceramic substrate, 11 pressure measuring holes, 12PCB board, 13O type sealing ring, 14 guide post, 15 sealing sleeve, 16 vent hole, 17 heat Riveted posts, 18 cavities, 19 fuel tanks, 20 microchannels.

Detailed ways

As shown in Figures 1-3, it is a sensor for measuring the internal pressure of a tank for storing volatile liquids, including a shell 3, the shell 3 is made of nylon material by injection molding, and the shell 3 is provided with a cavity 18. A PCB board 12 is installed in the cavity 18, and a pressure sensor assembly 10 is arranged on the PCB board 12. One end of the housing 3 is provided with a plug-in port 1, and the housing 3 is embedded with a plug-in terminal 2. The plug-in terminal 2 One end extends into the plug port 1, the other end of the plug terminal 2 is electrically connected to the PCB board 12, the upper side of the housing 3 is provided with an upper cover 5 that covers the cavity 18, and the lower side of the housing 3 is provided with a tank for connection and installation The guide post 14 is provided with a sealing sleeve 15, the sealing sleeve 15 is made of fluorine-containing rubber material, the guide post 14 has a barb structure to prevent the sealing sleeve 15 from slipping off, and the center of the guide post 14 is provided with a pass through. Air hole 16, a pressure measuring hole 11 is provided on the PCB board 12 corresponding to the vent hole 16, and the lower side of the pressure measuring hole 11 on the PCB board 12 is sealed with the housing 3; the vent hole 16 is connected through the pressure measuring hole 11. The pressure measuring surface of the pressure sensor assembly 10 is connected to the atmosphere, and the opposite side of the pressure measuring surface of the pressure sensor assembly 10 is connected to the atmosphere.

An O-ring 13 is provided between the lower side of the pressure measuring hole 11 on the PCB board 12 and the casing 3 , and the O-ring 13 is made of fluorine-containing rubber material. The hot riveting column 17 is riveted and connected; the periphery of the upper cover 5 and the casing 3 are sealed and bonded by the sealant 4 .

The upper side of the upper cover 5 is provided with a dust-proof connecting seat 8 that protrudes upward, a dust-proof cover 6 is installed on the dust-proof connecting seat 8, and the center of the dust-proof connecting seat 8 is provided with a ventilation hole 7 penetrating the upper cover 5, so A micro-channel 20 connected to the atmosphere is left between the dust cover 6 and the dust connection base 8 . The inner side of the upper cover 5 is provided with a waterproof and breathable membrane 9 corresponding to the ventilation holes 7 . It can prevent external muddy water or dust from blocking the ventilation holes 7.

The pressure sensor assembly 10 includes a ceramic substrate 1005 disposed above the PCB board 12 . The ceramic substrate 1005 is provided with a sensor unit plastic package 1004 . Element 1001 and conditioning chip 1002, the upper side of the sensing element 1001 communicates with the atmosphere, and the pressure measuring hole 11 also penetrates the ceramic substrate 1005, so that the lower side of the sensing element 1001 is connected with the vent hole 16, thereby forming a differential pressure sensor for pressure The conditioning chip 1002 , which converts the difference signal into a voltage signal, is electrically connected with the sensing element 1001 .

When working, as shown in Figure 4, it is installed on the fuel tank 19, the vapor pressure P1 generated by gasoline vapor acts under the sensing diaphragm of the sensing element 1001 through the air guide hole, and the pressure generated by atmospheric pressure P2, P1-P2 The voltage difference ΔP is generated and the resistance bridge on the induction diaphragm is deformed to generate the corresponding voltage difference signal. The differential pressure signal is conditioned into a voltage signal of 0.5V-4.5V through the conditioning chip 1002 on the sensing component according to the preset calibration parameters and range, and is transmitted to the ECU through the connector. The sensor of the present invention can also be located on the breathing line of the fuel tank or on the carbon canister according to the position.

The present invention is not limited to the above-mentioned embodiments. On the basis of the technical solutions disclosed in the present invention, those skilled in the art can make some substitutions and modifications to some of the technical features according to the disclosed technical contents without creative work. Modifications, replacements and modifications are all within the protection scope of the present invention.

Claims (7)

1. A sensor for measuring the internal pressure of a storage volatile liquid tank, comprising a housing, characterized in that: the housing is provided with a cavity, a PCB board is installed in the cavity, and the PCB board is provided with a pressure sensor One end of the housing is provided with a plug-in port, a plug-in terminal is embedded in the case, one end of the plug-in terminal extends into the plug-in port, the other end of the plug-in terminal is electrically connected to the PCB board, and the upper side of the case is provided with a cover hole. The upper cover of the cavity, the lower side of the casing is provided with a guide post for connection and installation with the tank body, the center of the guide post is provided with a vent hole, a sealing sleeve is installed on the guide post, and the PCB board is provided with a pressure measurement corresponding to the vent hole The lower side of the pressure measuring hole on the PCB board is sealed with the casing; the vent hole is connected to the pressure measuring surface of the pressure sensor assembly through the pressure measuring hole, and the pressure measuring surface of the pressure sensor assembly is opposite to the other side. Open to the atmosphere on one side. 2. A sensor for measuring the internal pressure of a storage volatile liquid tank according to claim 1, wherein an O-type seal is provided between the lower side of the pressure measuring hole on the PCB and the housing The PCB board and the casing are riveted and connected by hot riveting posts; the periphery of the upper cover and the casing are sealed and bonded by sealant. 3. A sensor for measuring the internal pressure of a storage volatile liquid tank according to claim 1, wherein the upper side of the upper cover is provided with a dust-proof connection seat that protrudes upward, and the dust-proof connection seat A dust-proof cover is installed on the top, and a ventilation hole penetrating the upper cover is arranged in the center of the dust-proof connection seat, and a micro-channel connected to the atmosphere is left between the dust-proof cover and the dust-proof connection seat. 4 . The sensor for measuring the internal pressure of a tank for storing volatile liquids according to claim 3 , wherein the inside of the upper cover is provided with a waterproof and breathable membrane corresponding to the ventilation holes. 5 . 5 . The sensor for measuring the internal pressure of a tank for storing volatile liquids according to claim 1 , wherein the pressure sensor assembly comprises a ceramic substrate disposed above the PCB board. 6 . , There is a sensor unit plastic-encapsulated casing on the ceramic substrate. The sensor unit plastic-encapsulated casing is fixed with crystal glue to fix the sensing element and the conditioning chip. The upper side of the sensing element is connected to the atmosphere, and the lower side of the sensing element is connected to the ventilation hole. , forming a differential pressure sensor, which is used for electrical connection between the conditioning chip for converting the differential pressure signal into a voltage signal and the sensing element. 6 . The sensor for measuring the internal pressure of a tank for storing volatile liquids according to claim 1 , wherein the guide post has a barb structure to prevent the sealing sleeve from slipping off. 7 . 7. The sensor for measuring the internal pressure of a tank for storing volatile liquids according to any one of claims 1-4, characterized in that: the shell is made of nylon material by injection molding; the O-shaped seal The ring and sealing sleeve are made of fluororubber material.

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