CN103968975B - Based on the anti-corrosion pressure transducer of PDMS pressure drag and stainless steel electric capacity - Google Patents

Abstract

The invention discloses a kind of anti-corrosion pressure transducer based on PDMS pressure drag and stainless steel electric capacity.Comprise airtight anti-corrosion housing and the PDMS pressure drag sensing unit be arranged in anti-corrosion housing and stainless steel capacitive sensing cells.Anti-corrosion housing is assembled successively by the bolt head of hollow, stainless steel barrier film, capping, nut; The inertia rubber top electrode substrate that PDMS pressure drag sensing unit has detecting electrode by dielectric film, PDMS piezoresistance layer and lower surface forms; Stainless steel capacitive sensing cells is made up of the stainless steel film pole plate of center drilling and backing substrate.Set of the present invention pressure resistance type and condenser type two kinds of power sensing units, effectively realize the second order measurement amount of static force and transient force, improves and measure efficiency and precision; Select SS316 stainless steel as the anti-corrosion housing of sensor, the features such as its excellent strong corrosion resistant meet the pressure survey requirement of sensor under corrosive gas and liquid.

Description

Based on the anti-corrosion pressure transducer of PDMS pressure drag and stainless steel electric capacity

Technical field

The present invention relates to a kind of pressure transducer, especially relate to a kind of anti-corrosion pressure transducer based on PDMS pressure drag and stainless steel electric capacity.

Background technology

Pressure monitor is a widely used field, has very important application in chemical process automation, Aero-Space and auto industry.Pressure transducer can be used for detecting the gas leakage of cylinder, tyre inner pressure, the temperature difference on engine internal pressure differences, surface and oil pressure etc.The pressure transducer being applied to these fields not only has clear and definite requirement for static force and transient force equal pressure measurement type, and under being often operated in extremely harsh environment, needs high temperature resistance, corrosion resistant ability.

Pressure transducer conventional at present comprises piezoresistive transducer, capacitance type sensor, piezoelectric transducer etc.Wherein piezoresistive transducer is the sensor manufactured based on piezoresistive effect, and its feature is that processing is simple, and signal is easy to measure, and is particularly suitable for the measurement of static force; Capacitance type sensor is characterized in that structure is simple, highly sensitive, and dynamic response is fast, but is difficult to avoid due to charge leakage, is not suitable for the measurement of static force, but with the obvious advantage in transient force measurement; The sensor that piezoelectric transducer manufactures based on piezoelectric effect, feature is that volume is little, and dynamic response is fast, but also there is charge leakage, be not suitable for the measurement of static force, and lateral bearing capacity is more weak, is not suitable for the pressure detection under rugged surroundings.Measure while realizing static force and transient force, for pressure monitor field, there is important scientific research value and engineering significance.

The field of pressure monitor is needed in chemical process automation, Aero-Space etc., its working environment often very severe, the pressure transducer worked under this kind of environment all needs to possess high temperature resistance, corrosion resistant ability, also will adhere to the requirement of high stable, highly reliable, low-power consumption, dynamic test etc. simultaneously.

Summary of the invention

The object of this invention is to provide a kind of anti-corrosion pressure transducer based on PDMS pressure drag and stainless steel electric capacity.

The technical solution adopted for the present invention to solve the technical problems is:

Based on the anti-corrosion pressure transducer of PDMS pressure drag and stainless steel electric capacity, by anti-corrosion housing, be arranged on PDMS pressure drag sensing unit in anti-corrosion housing and stainless steel capacitive sensing cells combines, wherein:

1) anti-corrosion housing comprises the bolt head of hollow, stainless steel barrier film, capping and nut and is assembled into an airtight cavity successively;

2) PDMS pressure drag sensing unit realizes the measurement of static force, and the inertia rubber top electrode substrate having a detecting electrode by dielectric film, PDMS piezoresistance layer and lower surface successively from bottom to up forms; The dielectric film of PDMS pressure drag sensing unit is arranged on the stainless steel barrier film of anti-corrosion housing;

3) stainless steel capacitive sensing cells realizes the measurement of transient force, is made up of successively from bottom to up the stainless steel film pole plate of center drilling and backing substrate; The stainless steel film pole plate of stainless steel capacitive sensing cells is arranged on the inertia rubber top electrode substrate of PDMS pressure drag sensing unit, and the capping bottom surface of anti-corrosion housing is arranged on the backing substrate of stainless steel capacitive sensing cells.

PDMS piezoresistance layer center has four PDMS power sensitive components, fan-shaped all in 75 °, and surrounding a diameter is the annulus of 3mm; Four PDMS power sensitive components are parallel-connection structure and are interconnected by electric loop; The center input end T of inertia rubber top electrode substrate lower surface detecting electrode ₀with the output terminal T of surrounding ₁~ T ₄circuit and four PDMS power sensitive components form four pressure drag unit, its resistance is expressed as R ₁, R ₂, R ₃, R ₄, form shunt circuit, power sensitive components is fan-shaped distribution, the uneven measured deviation caused of effect of can effectively releasing the pressure.

The stainless steel film pole plate of center drilling is as the bottom crown of stainless steel capacitive sensing cells, and diameter is 10mm, and film electrode thickness is 100 μm, and center drilling diameter is 5mm, and the degree of depth of center drilling is 20 μm.Backing substrate is as the top crown of stainless steel capacitive sensing cells, and be coated with insulating layer coating by the tungsten carbide substrate lower surface at ultrahigh hardness and process, insulation course is towards the stainless steel film pole plate side of center drilling.

Capacitive sensing cells is divided into non-contact measurement and two stages of contact type measurement, and when force value is little, stainless steel film can not touch backing substrate, is non-contact measurement; After force value increase makes stainless steel film touch backing substrate, sensing unit enters the contact type measurement stage, and the method effectively improves pressure measurement range.

The beneficial effect that the present invention has is:

1) adopt PDMS and stainless steel material to devise anti-corrosion pressure transducer, gathered pressure resistance type and condenser type two kinds of power sensing units, effectively realized the second order measurement amount of static force and transient force, improve and measure efficiency and precision.

2) select SS316 stainless steel as sensor housing, its excellent feature such as solid-state strain, dynamic property, strong corrosion resistant meets the pressure survey requirement of sensor under corrosive gas and liquid, can be widely used in the field such as Aero-Space, chemical process automation control.

Accompanying drawing explanation

Fig. 1 is sensor construction schematic diagram of the present invention.

Fig. 2 is the anti-corrosion housing three-dimensional, exploded view of the present invention.

Fig. 3 is PDMS pressure drag sensing unit layering schematic diagram of the present invention.

Fig. 4 is PDMS piezoresistance layer 2 d plane picture of the present invention.

Fig. 5 is PDMS pressure drag sensing unit inertia rubber top electrode substrate upward view of the present invention.

Fig. 6 is stainless steel capacitive sensing cells layering schematic diagram of the present invention.

Fig. 7 is stainless steel capacitive sensing cells sectional view of the present invention.

Fig. 8 is sensor construction explosive view of the present invention.

Fig. 9 is sensor of the present invention assembling schematic diagram.

In figure: 1, anti-corrosion housing, 2, PDMS pressure drag sensing unit, 3, stainless steel capacitive sensing cells, 4, the bolt head of hollow, 5, stainless steel barrier film, 6, capping, 7, nut, 8, dielectric film, 9, PDMS piezoresistance layer, 10, inertia rubber top electrode substrate, 11, electric loop, 12, PDMS power sensitive components, 13, detecting electrode, 14, stainless steel film pole plate, 15, backing substrate, 16, insulation course, 17, tungsten carbide substrate.

Embodiment

Below in conjunction with drawings and Examples, the invention will be further described.

As shown in Figure 1, Figure 2, shown in Fig. 8, Fig. 9, this sensor, by anti-corrosion housing 1, is arranged on PDMS pressure drag sensing unit 2 in anti-corrosion housing 1 and stainless steel capacitive sensing cells 3 combines, wherein:

Anti-corrosion housing 1: comprise the bolt head 4 of hollow, stainless steel barrier film 5, capping 6 and nut 7 and be assembled into an airtight cavity successively, assemble the cavity that rear formation one is airtight, PDMS pressure drag sensing unit 2 and stainless steel capacitive sensing cells 3 have been isolated from corrosive liquids or gaseous environment.

As shown in Fig. 3, Fig. 4, Fig. 5, PDMS pressure drag sensing unit 2: the inertia rubber top electrode substrate 10 having a detecting electrode 13 by dielectric film 8, PDMS piezoresistance layer 9 and lower surface successively from bottom to up forms; The dielectric film 8 of PDMS pressure drag sensing unit 2 is arranged on the stainless steel barrier film 5 of anti-corrosion housing 1; Select PDMS material manufacture piezoresistance layer and the object selecting inertia rubber as electrode substrate to be all to improve pliability, the stability of pressure drag sensing unit, thus make sensor more be adapted to the measurement environment of high temperature, high pressure, high vibration.

As shown in Figure 6, Figure 7, stainless steel capacitive sensing cells 3: be made up of the stainless steel film pole plate 14 of center drilling and backing substrate 15 successively from bottom to up; The stainless steel film pole plate 14 of stainless steel capacitive sensing cells 3 is arranged on the inertia rubber top electrode substrate 10 of PDMS pressure drag sensing unit 2, and capping 6 bottom surface of anti-corrosion housing 1 is arranged on the backing substrate 15 of stainless steel capacitive sensing cells 3.

As shown in Figure 4, Figure 5, described PDMS piezoresistance layer 9 center has four PDMS power sensitive components 12, fan-shaped all in 75 °, and surrounding a diameter is the annulus of 3mm; Four PDMS power sensitive components 12 are parallel-connection structure and are interconnected by electric loop 11; The center input end T of inertia rubber top electrode substrate 10 lower surface detecting electrode 13 ₀with the output terminal T of surrounding ₁~ T ₄circuit and four PDMS power sensitive components 12 form four pressure drag unit, its resistance is expressed as R ₁, R ₂, R ₃, R ₄, form shunt circuit, power sensitive components 12, in fan-shaped distribution, effectively can be released the pressure and act on the uneven measured deviation caused; The resistance of four pressure drag unit directly can be measured and obtain.

As shown in Figure 6, Figure 7, the stainless steel film pole plate 14 of described center drilling, as the bottom crown of stainless steel capacitive sensing cells 3, adopts the processing of SS316 stainless steel, diameter is 10mm, stainless steel film pole plate 14 thickness is 100 μm, and center drilling diameter is 5mm, and the degree of depth of center drilling is 20 μm.

As shown in Figure 6, Figure 7, described backing substrate 15 is as the top crown of stainless steel capacitive sensing cells 3, and be coated with insulating layer coating 16 by tungsten carbide substrate 17 lower surface at ultrahigh hardness and process, insulation course 16 is towards stainless steel film pole plate 14 side of center drilling.The stainless steel capacitive sensing cells 3 selecting the tungsten carbide material of ultrahigh hardness can reduce to disturb pressure to produce is out of shape, and improves measuring accuracy.Stainless steel capacitive sensing cells 3 is divided into non-contact measurement and two stages of contact type measurement, and when force value is little, stainless steel film pole plate 14 can not touch backing substrate, is non-contact measurement; After force value increase makes stainless steel film pole plate 14 touch backing substrate, stainless steel capacitive sensing cells 3 enters the contact type measurement stage, and the method effectively improves pressure measurement range.

Principle of work of the present invention is:

PDMS pressure drag sensing unit 2 realizes the measurement of static force, supposes that PDMS is ideal material, then static pressure p _sact on the four groups of pressure drag cell resistance amount changes caused can be expressed as:

ΔR ₁＝kp _sR ₁(1)

ΔR ₂＝kp _sR ₂(2)

ΔR ₃＝kp _sR ₃(3)

ΔR ₄＝kp _sR ₄(4)

Wherein k is pressure drag cell resistance coefficient.

Because sensor design adopts electrode T ₁~ T ₄become symmetrical Structural assignments, therefore can be obtained by the symmetry of four electrodes:

${\mathrm{kp}}_s=\frac{1}{4}(\frac{\mathrm{\Δ}{R}_1}{R_1}+\frac{\mathrm{\Δ}{R}_2}{R_2}+\frac{\mathrm{\Δ}{R}_3}{R_3}+\frac{\mathrm{\Δ}{R}_4}{R_4})---\left(5\right)$

Stainless steel capacitive sensing cells 3 realizes the measurement of transient force, and be divided into non-contact measurement and two stages of contact type measurement, when force value is little, stainless steel film pole plate 14 can not touch backing substrate, is non-contact measurement.When stainless steel capacitive sensing cells 3 is in this stage, the deflection of stainless steel film pole plate 14 is shown below:

$w(r,p_t)=\frac{p_t{a}^4}{64D}{(1-{\left(\frac{r}{a}\right)}^2)}^2---\left(6\right)$

In formula, p _trepresent tested transient pressure value, a represents stainless steel film pole plate radius, and D represents the flexural stiffness of film, and r represents the position of measured point.

Obtained by formula (6), now the capacitance of stainless steel capacitive sensing cells 3 is:

$C={\∫}_0^{2\mathrm{\π}}{\∫}_0^a\frac{{\mathrm{\ϵ}}_3{\mathrm{\ϵ}}_r\mathrm{rdrd\θ}}{t_0+{\mathrm{\ϵ}}_r\left(\mathrm{gw}\left(r{,p}_t\right)\right)}---\left(7\right)$

ε in formula ₀represent permittivity of vacuum, ε _rrepresent that backing substrate 15 surface is coated with the relative dielectric constant of insulating layer coating 16, t ₀be expressed as the thickness of backing substrate 15 insulation course 16, g represents the initial depth of stainless steel film pole plate 14 cavity.

After force value increase makes stainless steel film pole plate 14 touch backing substrate 15, stainless steel capacitive sensing cells 3 enters the contact type measurement stage, and now the deflection of stainless steel film pole plate 14 is depicted as:

$w(r,p_t)=\left\{\begin{array}{cc}g& 0<r<a_p\left(p_t\right)\\ g[1-[\frac{r-a_p\left(p_t\right)}{{(64\mathrm{Dg}/p_t)}^{1/4}}{]}^2{]}^2& a_p\left(p_t\right)<r<a\end{array}---\left(8\right)\right.$

A in formula _p(p _t) represent that stainless steel film pole plate 14 touches the edge radius of backing substrate 15, now the same through type of the capacitance of stainless steel capacitive sensing cells 3 (7) is tried to achieve.

The present invention adopts PDMS and stainless steel material to devise anti-corrosion pressure transducer, has gathered pressure resistance type and condenser type two kinds of power sensing units, has effectively realized the second order measurement amount of static force and transient force, improves and measures efficiency and precision; Select SS316 stainless steel as sensor housing, its excellent feature such as solid-state strain, dynamic property, strong corrosion resistant meets the pressure survey requirement of sensor under corrosive gas and liquid, can be widely used in the field such as Aero-Space, chemical process automation control.

Claims (3)

1. the anti-corrosion pressure transducer based on PDMS pressure drag and stainless steel electric capacity, it is characterized in that: this sensor, by anti-corrosion housing (1), is arranged on PDMS pressure drag sensing unit (2) in anti-corrosion housing (1) and stainless steel capacitive sensing cells (3) combines; Wherein:

1) anti-corrosion housing (1): comprise the bolt head (4) of hollow, stainless steel barrier film (5), capping (6) and nut (7) and be assembled into an airtight cavity successively;

2) PDMS pressure drag sensing unit (2): inertia rubber top electrode substrate (10) having a detecting electrode (13) by dielectric film (8), PDMS piezoresistance layer (9) and lower surface successively from bottom to up forms; The dielectric film (8) of PDMS pressure drag sensing unit (2) is arranged on the stainless steel barrier film (5) of anti-corrosion housing (1);

3) stainless steel capacitive sensing cells (3): be made up of the stainless steel film pole plate (14) of center drilling and backing substrate (15) successively from bottom to up; The stainless steel film pole plate (14) of the center drilling of stainless steel capacitive sensing cells (3) is arranged on inertia rubber top electrode substrate (10) of PDMS pressure drag sensing unit (2), and capping (6) bottom surface of anti-corrosion housing (1) is arranged on the backing substrate (15) of stainless steel capacitive sensing cells (3);

Described PDMS piezoresistance layer (9) center has four PDMS power sensitive components (12), fan-shaped all in 75 °, and surrounding a diameter is the annulus of 3mm; Four PDMS power sensitive components (12) are for parallel-connection structure and be interconnected by electric loop (11); The center input end T of inertia rubber top electrode substrate (10) lower surface detecting electrode (13) ₀with the output terminal T of surrounding ₁~ T ₄circuit and four PDMS power sensitive components (12) form four pressure drag unit, formed shunt circuit.

2. the anti-corrosion pressure transducer of a kind of PDMS pressure drag according to claim 1 and stainless steel electric capacity, it is characterized in that: the stainless steel film pole plate (14) of described center drilling is as the bottom crown of stainless steel capacitive sensing cells (3), diameter is 10mm, film electrode thickness is 100 μm, center drilling diameter is 5mm, and the degree of depth of center drilling is 20 μm.

3. the anti-corrosion pressure transducer of a kind of PDMS pressure drag according to claim 1 and stainless steel electric capacity, it is characterized in that: described backing substrate (15) is as the top crown of stainless steel capacitive sensing cells (3), be coated with insulating layer coating (16) by tungsten carbide substrate (17) lower surface at ultrahigh hardness to process, insulation course (16) is towards stainless steel film pole plate (14) side of center drilling.