CN217560858U

CN217560858U - Differential pressure sensor

Info

Publication number: CN217560858U
Application number: CN202221725288.5U
Authority: CN
Inventors: 沈建平
Original assignee: Shanghai Youcera Electronic Technology Co ltd
Current assignee: Shanghai Youcera Electronic Technology Co ltd
Priority date: 2022-07-05
Filing date: 2022-07-05
Publication date: 2022-10-11
Anticipated expiration: 2032-07-05

Abstract

The application relates to a differential pressure sensor, comprising: a base; the bearing piece is arranged on the base; the ceramic substrate is provided with a supporting part and a cantilever part, the bottom of the supporting part is borne on the top of the bearing part, the cantilever part is provided with a deformation area and a stress area, the deformation area is adjacent to the supporting part, and the stress area is arranged at one end, far away from the supporting part, of the cantilever part; four thick film resistors are sintered on the front surface and the back surface of the deformation area, the four thick film resistors form a Wheatstone bridge, and the output of the Wheatstone bridge is connected to the input end of the signal conditioning circuit. Above-mentioned differential pressure sensor, ceramic substrate have young's modulus height, characteristics that dielectric strength is high, and thick film resistor directly sintering is favorable to measurement accuracy's improvement at ceramic substrate, and the wheatstone bridge converts pressure into the signal of telecommunication, and sensitivity is higher, and the interference killing feature is strong, makes differential pressure sensor's measurement accuracy higher. The size of the ceramic substrate is reduced, so that the volume of the differential pressure sensor can be smaller. In addition, the differential pressure sensor has low cost.

Description

Differential pressure sensor

Technical Field

The application relates to the technical field of pressure sensors, in particular to a differential pressure sensor.

Background

A pressure sensor is a device or apparatus that senses a pressure signal and converts the pressure signal into a usable output electrical signal according to a certain rule. The pressure sensor is the most common sensor in industrial practice, is widely applied to various industrial automatic control environments, and relates to various industries such as water conservancy and hydropower, railway traffic, intelligent buildings, production automatic control, aerospace, war industry, petrochemical industry, oil wells, electric power, ships, machine tools, pipelines and the like. A pressure sensor is usually composed of a pressure sensitive element and a signal processing unit. The external force makes the pressure sensitive element change to generate a changed electric signal, the signal processing unit processes the changed electric signal and outputs a corresponding pressure value, thereby completing the pressure detection.

Pressure sensors can be classified into gauge pressure sensors, differential pressure sensors, and absolute pressure sensors according to different types of test pressures. There are three types of pressure sensors commonly used for measuring differential pressure: mechanical pressure sensor, metal suspension beam semiconductor strain gauge type pressure sensor and diffused silicon type pressure sensor. The mechanical pressure sensor is mainly of a mechanical structure type, and indicates pressure by deformation of an elastic element. The metal resistance strain gauge is a pressure sensitive element of a semiconductor strain gauge type pressure sensor stuck to a metal cantilever beam, and the working principle of the metal resistance strain gauge is that a strain resistor adsorbed on a substrate material generates resistance value change along with mechanical deformation, which is commonly called as resistance strain effect. The diffused silicon type pressure sensor is manufactured by packaging a silicon piezoresistive pressure sensitive element with isolation in a stainless steel shell. The pressure sensor can convert the sensed liquid or gas pressure into a standard electric signal to be output externally, and is widely applied to field measurement and control of industrial processes of water supply/drainage, heating power, petroleum, chemical industry, metallurgy and the like.

However, in the pressure sensor for measuring differential pressure in general, the mechanical pressure sensor has low measurement accuracy, the metal cantilever beam is attached to the strain gauge structure of the semiconductor strain gauge type sensor, and the diffused silicon type pressure sensor has high cost.

SUMMERY OF THE UTILITY MODEL

In view of the above, there is a need to provide a differential pressure sensor with high measurement accuracy, small volume and low cost.

A differential pressure sensor, comprising:

a base;

a carrier disposed on the base;

the ceramic substrate is provided with a supporting part and a cantilever part, the bottom of the supporting part is borne on the top of the bearing part, the cantilever part is provided with a deformation area and a stress area, the deformation area is adjacent to the supporting part, and the stress area is arranged at one end, far away from the supporting part, of the cantilever part; and with

The thick film resistor, the deformation zone is fixed with four thick film resistors, four thick film resistors constitute the Wheatstone bridge, the output of Wheatstone bridge connects signal conditioning circuit's input.

In one embodiment, when the stress area is stressed, the deformation area deforms, so that the resistance values of the four thick film resistors fixed in the deformation area change, and the wheatstone bridge generates a voltage variation corresponding to the deformation, and the voltage variation is processed by the signal conditioning circuit and then outputs a differential pressure signal.

In one embodiment, the base is provided with a limiting member, and the limiting member is used for limiting the pressing amount of the ceramic substrate when the stress area is stressed.

In one embodiment, the limiting member is arranged below the force bearing area.

In one embodiment, the top end of the supporting member has a branch line, the supporting portion is adjacent to the deformation region to form a boundary line on the bottom surface of the ceramic substrate, the supporting member is supported on the boundary line of the ceramic substrate at the branch line, and the deformation region is deformed from the boundary line when the cantilever portion is pressed downward.

In one embodiment, two of the four thick film resistors are arranged on two sides of the ceramic substrate in a mirror image mode.

In one embodiment, the ceramic substrate is a 96% alumina ceramic substrate.

In one embodiment, the thick film resistor is sintered to the ceramic substrate.

In one embodiment, the cantilever portion further has a signal processing area, and the signal processing area is used for arranging the signal conditioning circuit.

Above-mentioned differential pressure sensor sets up the deformation zone at ceramic substrate to fixed thick film resistor on the deformation zone, ceramic substrate has young modulus height, characteristics that dielectric strength is high, thick film resistor is used as precision resistor commonly, thick film resistor and ceramic substrate's combination is favorable to measurement accuracy's improvement, the wheatstone bridge that four thick film resistors are constituteed utilizes the output principle of electric bridge, converts pressure into the signal of telecommunication, this signal of telecommunication sensitivity is higher, the interference killing feature is strong, messenger differential pressure sensor's measurement accuracy is higher. Meanwhile, the thickness of the ceramic substrate is reduced, and the proportion of the ceramic substrate supporting part and the cantilever part is reduced, so that the cantilever part can deform when receiving smaller pressure, the measurement of the smaller pressure is further completed, and the precision of differential pressure detection can be further improved. Moreover, by reducing the size of the ceramic substrate, the size and the volume of the differential pressure sensor can be smaller on the premise of not influencing the measurement precision. In addition, the ceramic substrate, the thick film resistor and the signal conditioning circuit are low in cost, and the differential pressure sensor is simple in structure and low in cost.

Drawings

FIG. 1 is a schematic diagram of a differential pressure sensor according to one embodiment;

FIG. 2 is a left side view of FIG. 1;

FIG. 3 is a schematic view of the back and front sides of the ceramic substrate of FIG. 1;

FIG. 4 is a schematic circuit diagram of a differential pressure sensor of one embodiment.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some embodiments of the present application, but not all embodiments. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments in the present application without making any creative effort belong to the protection scope of the present application.

It will be understood that when an element is referred to as being "secured to" or "disposed" on another element, it can be directly on the other element or intervening elements may also be present. When a component is referred to as being "connected" to another component, it can be directly connected to the other component or intervening components may also be present. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and the like as used in the description of the present application are for illustrative purposes only and do not represent the only embodiments.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or to implicitly indicate the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the feature. In the description of the present application, "plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.

In this application, unless expressly stated or limited otherwise, the first feature "on" or "under" the second feature may mean that the first feature is in direct contact with the second feature, or that the first feature and the second feature are in indirect contact via an intermediate. Also, a first feature "on," "over," and "above" a second feature may be directly or diagonally above the second feature, or may simply indicate that the first feature is at a higher level than the second feature. A first feature "under," "beneath," and "under" a second feature may be directly under or obliquely under the second feature, or may simply mean that the first feature is at a lesser elevation than the second feature.

Unless defined otherwise, all technical and scientific terms used in the specification of the present application have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs. The terminology used in the description of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used in the description of the present application, the term "and/or" includes any and all combinations of one or more of the associated listed items.

As shown in fig. 1, fig. 2 and fig. 3, in one embodiment, a differential pressure sensor includes a base 100, a carrier 200, a ceramic substrate 300 and a thick film resistor 400.

And a base 100 for mounting and fixing core components of the differential pressure sensor.

And a carrier 200 disposed on the base 100. Generally, the carrier 200 is fixed to one side of the upper surface of the base 100.

The ceramic substrate 300 has a supporting portion 310 and a cantilever portion 320, the bottom of the supporting portion 310 is supported and fixed on the top of the supporting member 200, and the cantilever portion 320 is suspended so that the cantilever portion 320 is bent and deformed downward when being pressed downward. The cantilever 320 has a deformation region 322 and a stress region 324, the deformation region 322 is adjacent to the support portion 310, and the stress region 324 is disposed at an end of the cantilever 320 away from the support portion 310. Specifically, the stress area 324 is a pressure receiving area of the differential pressure sensor, and generally, a stress point is disposed at the top of the stress area 324, and after the stress point receives a pressure, the cantilever portion 320 bends and deforms downward, and this deformation may cause a surface area and a shape of the deformation area 322 of the cantilever portion 320 to slightly change.

The thick film resistor 400 and the deformation area 322 are fixed with four thick film resistors 400, the four thick film resistors 400 form a wheatstone bridge, which is four bridge arms of the wheatstone bridge, when the deformation area 322 deforms, the resistance values of the thick film resistors in the four bridge arms of the wheatstone bridge are caused to change, according to the principle of the wheatstone bridge, the bridge output bridge arms generate a voltage change amount corresponding to the deformation, and the change amount corresponds to the stress magnitude of the stress area 324 of the cantilever part 320 and is linear. The Wheatstone bridge is electrically connected with the signal conditioning circuit, and the acting force of the cantilever part 320 pressed is converted into programmable analog or digital signals to be output through the signal conditioning circuit, so that the purpose of measuring differential pressure is realized.

Above-mentioned differential pressure sensor sets up the deformation zone at ceramic substrate to fixed thick film resistor on the deformation zone, ceramic substrate has young modulus height, characteristics that dielectric strength is high, thick film resistor is used as precision resistor commonly, thick film resistor and ceramic substrate's combination is favorable to measurement accuracy's improvement, the wheatstone bridge that four thick film resistors are constituteed utilizes the output principle of electric bridge, converts pressure into the signal of telecommunication, this signal of telecommunication sensitivity is higher, and the interference killing feature is strong, makes differential pressure sensor's measurement accuracy higher. Meanwhile, the thickness of the ceramic substrate is reduced, and the proportion of the ceramic substrate supporting part and the cantilever part is reduced, so that the cantilever part can deform when receiving smaller pressure, the measurement of the smaller pressure is further completed, and the precision of differential pressure detection can be further improved. Moreover, by reducing the size of the ceramic substrate, the size and the volume of the differential pressure sensor can be smaller on the premise of not influencing the measurement precision. In addition, the ceramic substrate, the thick film resistor and the signal conditioning circuit are low in cost, and the differential pressure sensor is simple in structure and low in cost.

In this embodiment, when the stress area 324 is stressed, the deformation area 322 deforms, so that the resistances of the four thick film resistors 400 fixed in the deformation area 322 change, and thus the wheatstone bridge generates a voltage variation corresponding to the deformation, and the voltage variation is processed by the signal conditioning circuit and then outputs a differential pressure signal. The cantilever 320 has a signal processing area 326, and the signal conditioning circuit is disposed at the signal processing area 326.

Referring to fig. 4, the signal conditioning circuit is a schematic circuit diagram of a differential pressure sensor, and a digital conditioning chip is used as the signal conditioning circuit. The specific digital conditioning chip is a DC102 chip. The DC102 chip is a CMOS integrated circuit specially used for processing and outputting signals of a differential resistance bridge type or half-bridge type sensor, and is widely applied to sensor signal conditioning in the fields of building automatic control, automobiles, industrial control, office automation, white appliances and the like. The Wheatstone bridge signal is accessed to the DC102 chip, is acquired and converted by a high-precision analog-to-digital converter in the DC102 chip, is processed by the chip, and is output in a digital or analog mode through a single-wire interface, so that the control circuit can read and process the signal conveniently. For Wheatstone bridge signals, the DC102 chip can perform high-precision amplification and up to 14bit analog-to-digital conversion. The gain of the built-in amplifier and the offset of the analog signal input range are settable. The DC102 chip integrates a built-in temperature sensor (or an external temperature sensor can be used), and can output digitally compensated temperature information. The DC102 chip is provided with a digital signal processing circuit, and can perform digital compensation on the measurement result of the sensor, including first-order or second-order compensation on the offset, sensitivity, temperature drift and nonlinearity of the signal. The gain of the amplifier, the signal input range, the coefficient of the compensation algorithm and other data can be written into an electrically erasable programmable read-only memory (EEPROM) integrated by a chip through a single wire interface, and the DC102 chip is also provided with a DAC (digital-to-analog converter) with 12-bit and an output buffer, so that an analog signal in proportional linear relation with the differential input of the sensor can be conveniently output. After a voltage stabilizing circuit is formed by externally connecting a field effect transistor, the DC102 can directly work at the power supply voltage up to 30V, and the requirements of a plurality of industrial control applications are conveniently met. The DC102 chip pin definition is shown in table 1:

TABLE 1

Specifically, a Bsink pin, a VBP pin and a VBN pin of the DC102 chip are respectively connected with three wiring ends of a Wheatstone bridge consisting of thick film resistors, and a fourth wiring end of the Wheatstone bridge is connected with input voltage through a Junction Field Effect Transistor (JFET). The grid electrode of the JFET is connected with a GATE pin, an ExTemp pin is grounded through a diode, a VDD pin is connected with a source electrode of the JEFT and is grounded through a capacitor, a VSS pin is grounded, and an SIO pin serves as a signal output end. The DC102 chip is provided with temperature compensation, so that the interference of temperature change on the differential pressure sensor is reduced. The dashed connections and Optional in fig. 4 represent Optional connections. Group represents Ground. OUT represents the output signal of the DC102 chip.

In the embodiment, the base 100 is provided with the limiting member 110, and the limiting member 110 is used for limiting the pressing amount of the ceramic substrate 300 when the stress area 324 is stressed, so as to limit the deformation amount of the deformation area 322 and protect the ceramic substrate from being damaged by overload.

Specifically, the limiting member 110 is disposed below the force-bearing zone 324. After the top of the stress area 324 is pressed downwards, the cantilever part 320 bends downwards, the deformation area 322 deforms, the resistance value of the thick film resistor 400 in the deformation area 322 changes, when the stress area presses the bottom of the cantilever part 320 to be in contact with the top of the limiting part 110, the deformation amount of the deformation area 322 is the largest, the resistance value of the front thick film resistor 400 becomes the largest, meanwhile, the resistance values of the two back thick film resistors become the smallest due to compression, and under the condition, the output of the Wheatstone bridge is the largest. The limiting member 110 is used to protect the ceramic substrate 300 from being damaged under an overload condition.

In the present embodiment, the top end of the carrier 200 has a branch line 210, and the adjacent position of the supporting portion 310 and the deformation region 322 forms a boundary line on the bottom surface of the ceramic substrate 300. The carrier 200 is supported at the boundary of the ceramic substrate 300 at the branch line 210. When the cantilever 320 is pressed downward, the deformation region 322 starts to deform from the dividing line. The branch line 210 is a connecting line that mainly supports the cantilever 320, and when the cantilever 320 is pressed down, the interaction force between the ceramic substrate 300 and the carrier 200 is stronger at the branch line 210. The branch line 210 is parallel to the boundary line, and the quality of the branch line 210, or the accuracy of the straight smoothness of the surface of the branch line 210, and the quality of the boundary line, or the accuracy of the straight smoothness of the surface of the boundary line, and the accuracy of the parallel between the branch line 210 and the boundary line determine the stability of the deformation region 322 when it is deformed, which has a large influence on the accuracy and stability of the resistance value change of the thick film resistor 400. At the same time, the service life of the ceramic substrate 300 and the carrier 200, i.e., the service life of the differential pressure sensor, is also affected.

In the present embodiment, two thick film resistors 400 are respectively arranged on both sides of the ceramic substrate 300 in a mirror image manner. When the ceramic substrate 300 is pressed down by a force, the resistances of the two thick film resistors 400 on the front surface (upper surface) are increased, and the resistances of the two thick film resistors on the back surface (lower surface) are decreased. The ceramic substrate 300 is a 96% alumina ceramic substrate. The thick film resistor 400 is sintered on the ceramic substrate 300. The characteristics of high Young modulus, high insulating strength, high temperature resistance, strong corrosion resistance, high processing efficiency, low cost and the like of the 96% alumina ceramic substrate are utilized, the 96% alumina ceramic substrate is used as a main body structure, the thick film resistor 400 is directly sintered on the 96% alumina ceramic substrate by using a screen printing technology in the deformation area 322 of the cantilever part 320 to form a Wheatstone bridge, the output principle of the bridge is utilized to convert pressure into an electric signal, the signal has extremely high sensitivity and strong anti-interference capability, can be used for measuring micro-differential pressure, and programmable analog or digital output signals are obtained through a signal conditioning circuit integrated on the substrate. By adopting the silk-screen thick film circuit Technology and the SMT (Surface Mounted Technology), the manufacturing process is suitable for automatic large-scale production, the production efficiency is high, and the material cost is low. In addition, the differential pressure sensor adopts a force-electricity integrated technology, and the sensor is provided with temperature compensation, so that the assembly and debugging efficiency of subsequent application products is greatly improved. By adjusting the length-width ratio between the cantilever 320 and the support 310 or the thickness of the ceramic substrate 300, an extremely wide measurement range can be manufactured.

The working principle of the differential pressure sensor is as follows: when the stress point of the ceramic substrate 300 is pressed downwards, the ceramic substrate 300 will generate a downward bending deformation along the branch line, the deformation will cause the surface area and shape of the deformation zone 322 of the ceramic substrate 300 to slightly change, a wheatstone bridge composed of four thick film resistors 400 is sintered on the front and back sides of the deformation zone 322 of the ceramic substrate 300, the resistance value of the thick film resistor 400 sintered on the wheatstone bridge is changed due to the change of the surface area and shape of the substrate, and according to the principle of the wheatstone bridge, the bridge output bridge arm will generate a voltage variation corresponding to the deformation, and the variation corresponds to the stress size of the cantilever part 320 structure and is linear. The signal conditioning circuit integrated on the ceramic substrate 300 converts the force applied by the cantilever 320 into a programmable analog or digital signal for output, thereby achieving the purpose of measuring differential pressure.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present application. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims

1. A differential pressure sensor, comprising:

a base;

a carrier disposed on the base;

the ceramic substrate is provided with a supporting part and a cantilever part, the bottom of the supporting part is borne on the top of the bearing part, the cantilever part is provided with a deformation area and a stress area, the deformation area is adjacent to the supporting part, and the stress area is arranged at one end, far away from the supporting part, of the cantilever part; and

2. The differential pressure sensor according to claim 1, wherein when the force-bearing area is subjected to a force, the deformation area deforms, so that the resistances of the four thick film resistors fixed in the deformation area change, and the wheatstone bridge generates a voltage variation corresponding to the deformation, and the voltage variation is processed by the signal conditioning circuit and then outputs a differential pressure signal.

3. The differential pressure sensor according to claim 1, wherein a stopper is provided on the base for limiting a pressing amount of the ceramic substrate when the force receiving area receives a force.

4. The differential pressure sensor of claim 3, wherein the stop is disposed below the force-bearing zone.

5. The differential pressure sensor according to claim 1, wherein the top end of the carrier has a fulcrum line, the support portion forms a boundary line with the bottom surface of the ceramic substrate adjacent to the deformation region, the carrier is supported at the boundary line of the ceramic substrate at the fulcrum line, and the deformation region is deformed from the boundary line when the cantilever portion is pressed downward.

6. The differential pressure sensor according to claim 1, wherein the four thick film resistors are arranged on both sides of the ceramic substrate in a mirror image manner with respect to each other in pairs.

7. The differential pressure sensor of claim 6, wherein the ceramic substrate is a 96% alumina ceramic substrate.

8. The differential pressure sensor of claim 7, wherein the thick film resistor is sintered to the ceramic substrate.

9. The differential pressure sensor of claim 1, wherein the cantilever portion further has a signal processing region for positioning the signal conditioning circuitry.