Elastomer, strain type pressure sensor and processing method of strain type pressure sensor

Abstract

The invention relates to the technical field of strain type pressure sensors, in particular to an elastic body which comprises an elastic body, a blind hole is formed in the end face of the elastic body in the axial direction, the axis of the blind hole coincides with the axis of the elastic body, and an elastic diaphragm is arranged at the bottom of the blind hole; the contact surface of the elastic diaphragm and the medium to be measured is a segmented curved surface, and the thickness of the elastic diaphragm is changed according to a certain rule along with the change of the radius; the segmented curved surface comprises a positive strain area, a transition area and a negative strain area which are sequentially arranged in the radius direction of the elastic diaphragm; the profile curves of the positive strain area, the transition area and the negative strain area meet a first condition; the designed elastic body enables the strain of each resistance value of the strain type pressure sensor with different measuring ranges to tend to be balanced and reduces the deflection generated after the elastic body is pressed, so that the sensitivity of the strain type pressure sensor under each measuring range can be improved, and the indexes of nonlinearity, hysteresis, repeatability and the like can be reduced.

Description

Technical Field

[0001] The present application relates to the technical field of strain type pressure sensors, and in particular to an elastomer, a strain type pressure sensor and a processing method thereof. Background Art

[0002] A strain type pressure sensor is a device used to detect pressure, which mainly includes an elastomer, an intermediate layer and a sensitive grid; the intermediate layer is located between the elastomer and the sensitive grid, tightly connecting the elastomer and the sensitive grid; when the elastomer contacts the measured medium, the elastomer deforms under pressure, and the intermediate layer transfers the deformation of the elastomer to the sensitive grid. After the sensitive grid is strained by the intermediate layer, it will also strain itself, causing the resistance of the sensitive grid itself to change, and convert it into an electrical signal output through a Wheatstone bridge, thereby realizing the quantification of pressure information.

[0003] The contact surface between the elastic body and the medium to be measured of the existing strain type pressure sensor is generally a combination of a plane and a rounded corner. For a small-range strain type pressure sensor, the combination of a plane and a rounded corner contact surface with the medium to be measured will cause excessive strain in the radial strain area and affect the sensitivity, nonlinearity, hysteresis, repeatability and other indicators; while for a large-range strain type pressure sensor, the combination of a plane and a rounded corner contact surface with the medium to be measured will cause excessive strain in the tangential strain area and affect the sensitivity, nonlinearity, hysteresis, repeatability and other indicators.

[0004] In summary, there is an urgent need to find an elastomer that can guarantee indicators such as sensitivity, nonlinearity, hysteresis, and repeatability within different ranges of measurement. Summary of the invention

[0005] In order to ensure that the elastic body can ensure the sensitivity, nonlinearity, hysteresis, repeatability and other indicators within different measuring ranges, this application provides the following technical solutions:

[0006] In a first aspect, the present application provides an elastic body applied to a strain type pressure sensor, wherein the strain type pressure sensor comprises a radial resistor and a tangential resistor located on one side close to the elastic body, and is characterized in that it comprises:

[0007] The elastic body is a body of revolution structure, one end of the elastic body is provided with a blind hole along the axial direction, the axis of the blind hole coincides with the axis of the elastic body, and an elastic diaphragm is provided from the bottom of the blind hole to the other end of the elastic body, and the elastic diaphragm is used to receive the pressure change of the medium to be measured and convert the pressure change into its own deformation;

[0008] The thickness of the elastic diaphragm varies with the radius; the thickness distribution of the elastic diaphragm is used to ensure that the deformation amount of the elastic diaphragm corresponding to the area where the radial resistor and the tangential resistor in the strain-type pressure sensor are located satisfies a linear relationship with the pressure value to be detected.

[0009] In a possible implementation, the contact surface between the elastic diaphragm and the medium to be measured is a segmented curved surface, and the segmented curved surface includes a positive strain area, a transition area, and a negative strain area sequentially arranged along the radius direction of the elastic diaphragm;

[0010] The contour curves of the positive strain zone, the transition zone and the negative strain zone meet the first condition;

[0011] The first condition includes:

[0012] Taking the center of the circle of the elastic diaphragm away from the blind hole as the origin, setting the x-axis along the radial direction and the y-axis along the axial direction, establishing a contour curve coordinate system of the elastic diaphragm, the positive strain zone along the radial direction ranges from 0 to x0, the transition zone along the radial direction ranges from x0 to x1, and the negative strain zone along the radial direction ranges from x1 to x2;

[0013] The contour curve expression of the positive strain zone is y=f t (x)0 <x≤x0;

[0014] The profile curve expression of the transition zone is y=f g (x)x0 <x≤x1;

[0015] The contour curve expression of the negative strain zone is y=f l (x)x1 <x≤x2。

[0016] In a possible implementation, the positive strain zone is a plane, the transition zone is a curved surface connected to the plane, and the negative strain zone is a curved surface; and the contour curves of the positive strain zone, the transition zone, and the negative strain zone meet the second condition;

[0017] The second condition includes:

[0018] The contour curve of the positive strain zone satisfies the equation f t (x) = -h1 -h0 0 < x ≤ x0;

[0019] The contour curve of the transition zone satisfies the equation

[0020] f g2 (x) = h0 x 01 <x≤x1;

[0021] The contour curve of the negative strain zone satisfies the equation

[0022] Where h0 is the thickness of the diaphragm at the thinnest point; r0 is the inner diameter of the blind hole; h1 is the thickness of the boss at the center; R g is the arc radius length of the transition zone surface segment; a and b are the length of the major and minor semi-axis of the ellipse respectively; x 01 is the intersection point of the curve segment and the straight line segment in the transition zone in the x-axis direction, It is represented as the transition zone in the surface segment x0<x≤x 01 The surface equation in the range of f g2 (x) = -h0 represents the transition zone (122) at x 01 The equation of the plane in the range of <x≤x1.

[0023] In a possible implementation, the positive strain region, the transition region, and the negative strain region are all curved surfaces, and the contour curves of the positive strain region, the transition region, and the negative strain region satisfy the third condition;

[0024] The third condition includes:

[0025] The center coordinates of the positive strain zone are O1 (0, y1), the center coordinates of the transition zone are O2 (r0-R2, h0+R2), and the center coordinates of the negative strain zone (123) are O3 (r0-R3, -h0-R3);

[0026] The radius of the positive strain zone is R1, the radius of the transition zone is R2, and the radius of the negative strain zone is R3;

[0027] The positive strain zone contour curve satisfies the equation

[0028] The transition zone profile curve satisfies the equation

[0029] The negative strain zone contour curve satisfies the equation

[0030] Where h0 is the thickness of the diaphragm at the thinnest point; r0 is the inner diameter of the blind hole.

[0031] In a second aspect, a strain type pressure sensor includes: an elastic body, an intermediate layer and a sensitive grid; the sensitive grid includes a radial resistor and a tangential resistor.

[0032] In a third aspect, a method for processing a strain gauge pressure sensor comprises the following steps:

[0033] S1. Material handling;

[0034] S2, coating the fusing agent;

[0035] S3, fusing the steel plate and the foil material to form a composite plate;

[0036] S4, design elastic strain diaphragm;

[0037] S6. Processing the strain diaphragm according to the design results;

[0038] S7, etching the sensitive grid of the Wheatstone bridge;

[0039] S8. Split the composite plate.

[0040] An elastomer based on a strain-type pressure sensor and a design method thereof provided by the present application are used to divide a segmented curved surface into a positive strain zone, a transition zone and a negative strain zone, and the contour of each segment of the curved surface is defined by a function expression respectively. The function expression is then input into a simulation software, and simulation calculations are performed through the simulation software to obtain the optimal contour curves of the positive strain zone, the transition zone and the negative strain zone, and the elastomer is designed accordingly. This facilitates balancing the strains of various resistance values ​​of strain-type pressure sensors of different ranges and reducing the deflection of the elastomer after being compressed, which can not only improve the sensitivity of the strain-type pressure sensors under various ranges, but also reduce indicators such as nonlinearity, hysteresis and repeatability. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The accompanying drawings are used to provide a further understanding of the present application and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the present application and do not constitute a limitation to the present application.

[0042] Figure 1 This is a schematic diagram of an elastomer according to Example 1 of the present application.

[0043] Figure 2 It is a schematic diagram of a contour curve coordinate system of an elastic body in Example 1 of the present application.

[0044] Figure 3 It is a schematic diagram of a contour curve coordinate system of an elastic body in Example 2 of the present application.

[0045] Description of the drawings: 1. Elastomer; 11. Blind hole; 12. Elastic diaphragm; 121. Positive strain zone; 122. Transition zone; 123. Negative strain zone. DETAILED DESCRIPTION

[0046] In order to make the purpose, technical solutions and advantages of this application clearer, the technical solutions in this application will be clearly and completely described below in conjunction with the drawings in this application. Obviously, the described embodiments are part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0047] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features; in the description of this application, unless otherwise specified, "plurality" means two or more.

[0048] The following is combined with Figure 1-3 This application is described in further detail.

[0049] In a first aspect, this embodiment application discloses an elastomer.

[0050] Embodiment 1:

[0051] Reference Figure 1 and Figure 3 , an elastomer, comprising: an elastomer 1 applied to a strain type pressure sensor, the strain type pressure sensor comprising a radial resistor and a tangential resistor located on one side close to the elastomer 1, the elastomer 1 being arranged as a body of revolution structure, a blind hole 11 being axially provided on the end face of the elastomer 1, the axis of the blind hole 11 coinciding with the axis of the elastomer 1, an elastic diaphragm 12 being arranged at the bottom of the blind hole 11, the elastic diaphragm 12 being in contact with a medium to be measured, and the elastic diaphragm 12 being used to receive pressure changes of the medium to be measured and convert the pressure changes into its own deformation; the contact surface between the elastic diaphragm 12 and the medium to be measured is located at the bottom of the blind hole 11, and the contact surface is a segmented curved surface, and the thickness of the elastic diaphragm 12 changes with the radius; the thickness distribution of the elastic diaphragm 12 is used to make the deformation amount of the elastic diaphragm 12 corresponding to the area where the radial resistor and the tangential resistor are located in the strain type pressure sensor satisfy a linear relationship with the pressure value to be detected.

[0052] The segmented surface includes a positive strain zone 121, a transition zone 122 and a negative strain zone 123 arranged sequentially along the radial direction of the elastic diaphragm 12; the negative strain zone 123 is arranged close to the periphery of the elastic diaphragm; the contour curves of the positive strain zone 121, the transition zone 122 and the negative strain zone 123 meet the first condition.

[0053] The first condition includes the following:

[0054] Taking the center of the circle of the elastic diaphragm 12 away from the blind hole 11 as the origin, setting the x-axis along the radial direction and the y-axis along the axial direction, a contour curve coordinate system of the elastic diaphragm 12 is established, wherein the positive strain zone 121 along the radial direction ranges from 0 to x0, the transition zone 122 along the radial direction ranges from x0 to x1, and the negative strain zone 123 along the radial direction ranges from x1 to x2.

[0055] The contour curve expression of the positive strain region 121 is y=f t(x) 0 < x ≤ x0; The contour curve expression of the transition region 122 is y = f g (x) x0 < x ≤ x1; The contour curve expression of the negative strain region 123 is y = f l (x) x1 < x ≤ x2.

[0056] The positive strain region 121 is a plane, and the transition region 122 is a combination of a curved surface and a plane, and the negative strain region 123 is a curved surface; the contour curves of the positive strain region 121, the transition region 122, and the negative strain region 123 satisfy the second condition.

[0057] The second condition includes the following items:

[0058] The contour curve of the positive strain region 121 satisfies the equation f t (x) = -h1 - h0 0 < x ≤ x0;

[0059] The contour curve of the transition region 122 satisfies the equation

[0060] f g2 (x) = h0 x 01 <x ≤ x1;

[0061] The contour curve of the negative strain region 123 satisfies the equation

[0062] where h0 is the diaphragm thickness at the thinnest point; r0 is the inner diameter length of the blind hole 11, h1 is the thickness of the boss at the center; R g is the arc radius length of the curved surface section of the transition region 122; a and b are the major semi-axis length and the minor semi-axis length of the ellipse respectively; is expressed as the curved surface equation of the transition region 122 within the range of x0 < x ≤ x 01 and f g2 (x) = -h0 is expressed as the plane equation of the transition region 122 within the range of x 01 <x ≤ x1.

[0063] Example 2:

[0064] Refer to Figure 3 , The difference between this Example 2 and Example 1 is that the positive strain region 121, the transition region 122, and the negative strain region 123 are all curved surfaces, and the contour curves of the positive strain region 121, the transition region 122, and the negative strain region 123 satisfy the third condition;

[0065] The third condition includes the following items:

[0066] 1. The coordinates of the center of the positive strain zone 121 are O1 (0, y1), the coordinates of the center of the transition zone 122 are O2 (r0-R2, h0+R2), and the coordinates of the center of the negative strain zone 123 are O3 (r0-R3, -h0-R3); wherein the radius of the positive strain zone 121 is R1, the radius of the transition zone 122 is R2, and the radius of the negative strain zone 123 is R3.

[0067] 2. The contour curve of the positive strain zone 121 satisfies the equation

[0068] The profile curve of the transition zone 122 satisfies the equation

[0069] The contour curve of the negative feedback area 123 satisfies the equation

[0070] Where h0 is the thickness of the diaphragm at the thinnest point; r0 is the inner diameter length of the blind hole 11, f t (x), f g (x) and f l (x) represents the thickness of the elastic membrane in the positive strain region 121, the transition region 122 and the negative strain region 123 respectively.

[0071] In a second aspect, a strain type pressure sensor includes: an elastic body 1, an intermediate layer and a sensitive grid; the sensitive grid includes a radial resistor and a tangential resistor.

[0072] In a third aspect, a method for processing a strain gauge pressure sensor comprises the following steps:

[0073] S1. Material processing: The steel plate used for the elastomer is subjected to high temperature heat treatment and deep cryogenic treatment to make its hardness, stability, thermal expansion coefficient, elastic modulus, retained austenite, surface roughness and flatness meet the design requirements; the foil material is subjected to heat treatment to make its stability, thermal expansion coefficient and surface roughness reach the design values ​​and be infinitely close to the relevant parameters of the elastomer.

[0074] S2. Applying the flux; preparing the flux and applying it on the steel plate to ensure uniform coating.

[0075] S3, fusing the steel plate and the foil material to form a composite plate; laying the foil material flat on the flux coating of the steel plate, and using a joint press to fuse the steel plate and the foil material to form a composite plate of the elastomer and the foil material.

[0076] S4, design elastic strain diaphragm;

[0077] S51. According to the elastic body structure, the center of the elastic body structure is taken as the origin, and the strain area is set as the x-axis along the radial direction.

[0078] The axial direction of the strain zone is set as the y-axis, and the strain zone is divided into a positive strain zone, a transition zone and a negative strain zone along the radial direction, and a coordinate system of the contour curve of the elastic structure is established; the range of the positive strain zone along the radial direction is defined as 0~x0, the range of the transition zone along the radial direction is defined as x0~x1, and the range of the negative strain zone along the radial direction is defined as x1~x2;

[0079] S52, define the contour curve of the positive strain zone by the equation y=f t (x)0 <x≤x0;

[0080] The contour curve of the transition zone is defined by the equation y = f g (x)x0<x≤x1;

[0081] The contour curve of the negative strain area is defined by the equation f l (x)x1 <x≤x2。

[0082] S521, when the positive strain region 121 is a plane, the transition region 122 is a curved surface connected to the plane, and the negative strain region 123 is a curved surface, the contour curve equation of the positive strain region 121 is defined as: f t (x) = -h1 -h0 0 < x ≤ x0;

[0083] The profile curve equation of the transition region 122 is defined as:

[0084]

[0085] f g2 (x) = h0 x 01 <x≤x1;

[0086] The contour curve equation of the negative strain region 123 is defined as:

[0087]

[0088] Where h0 is the thickness of the diaphragm at the thinnest part; r0 is the inner diameter length of the blind hole 11; h1 is the thickness of the boss at the center; R g is the arc radius length of the curved surface segment of the transition zone 122; a and b are the length of the major semi-axis and the minor semi-axis of the ellipse respectively; It is represented as transition zone 122 in the surface segment x0<x≤x 01 The surface equation in the range of f g2 (x) = -h0 represents the transition region 122 at x 01 The equation of the plane in the range of <x≤x1.

[0089] S522, when the positive strain region 121, the transition region 122 and the negative strain region 123 are all curved surfaces,

[0090] The contour curve equation of the positive strain region 121 is defined as:

[0091] The profile curve equation of the transition region 122 is defined as:

[0092]

[0093] The contour curve equation of the negative feedback area 123 is defined as:

[0094]

[0095] Wherein, h0 is the thickness of the diaphragm at the thinnest point; r0 is the inner diameter length of the blind hole 11.

[0096] S53, the contour curve equations of the positive strain zone, the transition zone and the negative strain zone are simulated and calculated by simulation software,

[0097] The optimal contour curves of the positive strain zone, transition zone and negative strain zone are obtained; and the strain zone contour of the elastomer structure is designed according to the calculated optimal contour curves.

[0098] S6. Process the strain diaphragm according to the design results.

[0099] S7. Etch the Wheatstone bridge sensitive grid.

[0100] S71, coating a photosensitive adhesive on the surface of the foil material;

[0101] S72, exposing a Wheatstone bridge on the surface of the photosensitive resin according to the designed sensitive grid pattern, so that the center of the sensitive grid and the center of the strain area are located on the same straight line;

[0102] S73, using a developer to remove the exposed photosensitive resin, leaving a desired pattern;

[0103] S74, using dry or wet etching to remove the area not covered by the photosensitive resin to form a desired sensitive grid structure;

[0104] S75, remove the residual photosensitive resin and complete the etching.

[0105] S8. Splitting the composite plate. When splitting the composite plate, the composite plate is split into a plurality of pressure sensor shells with the line connecting the center of the strain zone and the center of the sensitive grid as the axis and the designed outer dimensions as the radius.

[0106] The above embodiments are only used to illustrate the technical solution of the present application, but not to limit it. The present application is not limited to the exact structure described above and illustrated in the accompanying drawings, and it cannot be determined that the specific implementation of the present application is limited to these descriptions. For ordinary technicians in the technical field to which the present application belongs, various changes and modifications made without departing from the concept of the present application should be deemed to belong to the protection scope of the present application.

Claims

1. An elastic body, applied to a strain type pressure sensor, the strain type pressure sensor comprising a radial resistor and a tangential resistor located near one side of the elastic body, characterized in that: include: The elastic body (1) is a rotating body structure, one end of the elastic body (1) is provided with a blind hole (11) along the axial direction, the axis of the blind hole (11) coincides with the axis of the elastic body (1), and an elastic diaphragm (12) is provided from the bottom of the blind hole (11) to the other end of the elastic body, and the elastic diaphragm (12) is used to receive pressure changes of the medium to be measured and convert the pressure changes into its own deformation; The thickness of the elastic diaphragm (12) varies with the radius; the thickness distribution of the elastic diaphragm (12) is used to ensure that the deformation amount of the elastic diaphragm (12) corresponding to the area where the radial resistor and the tangential resistor in the strain-type pressure sensor are located satisfies a linear relationship with the pressure value to be detected.

2. The elastic body according to claim 1, characterized in that The contact surface between the elastic diaphragm (12) and the medium to be measured is a segmented curved surface, and the segmented curved surface comprises a positive strain area (121), a transition area (122), and a negative strain area (123) arranged in sequence along the radial direction of the elastic diaphragm (12); The contour curves of the positive strain region (121), the transition region (122) and the negative strain region (123) satisfy a first condition; The first condition includes: Taking the center of the circle of the elastic diaphragm (12) away from the blind hole (11) as the origin, setting an x-axis along the radial direction and a y-axis along the axial direction, a contour curve coordinate system of the elastic diaphragm (12) is established, the positive strain zone (121) along the radial direction has a range of 0 to x0, the transition zone (122) along the radial direction has a range of x0 to x1, and the negative strain zone (123) along the radial direction has a range of x1 to x2; The contour curve expression of the positive strain zone (121) is y=f t (x ) 0 <x≤x0; The profile curve expression of the transition zone (122) is y=f g ( x ) x0 <x≤x1; The contour curve expression of the negative strain zone (123) is y=f l (x)x1 <x≤x2。 3. The elastic body according to claim 2, characterized in that The positive strain zone (121) is a plane, the transition zone (122) is a curved surface connected to the plane, and the negative strain zone (123) is a curved surface; and the contour curves of the positive strain zone (121), the transition zone (122) and the negative strain zone (123) meet the second condition; The second condition includes: The contour curve of the positive strain zone (121) satisfies the equation f t (x ) =-h1-h0 0 <x≤x0; The profile curve of the transition zone (122) satisfies the equation f g2 ( x ) =h0x 01 <x≤x1; The contour curve of the negative strain zone (123) satisfies the equation where h0 is the diaphragm thickness at the thinnest point; r0 is the inner diameter length of the blind hole, h1 is the thickness of the boss at the center; R g is the arc radius length of the curved surface section of the transition zone (122); a and b are the major semi-axis length and minor semi-axis length of the ellipse respectively; x 01 is the intersection point of the curved section and the straight section of the transition zone (122) in the x-axis direction, is expressed as the surface equation of the transition zone (122) in the range of x0 < x ≤ x 01 ; f g2 ( x ) = -h0 is expressed as the plane equation of the transition zone (122) in the range of x 01 < x ≤ x1.

4. The elastic body according to claim 2, characterized in that The positive strain region (121), the transition region (122), and the negative strain region (123) are all curved surfaces, and the contour curves of the positive strain region (121), the transition region (122), and the negative strain region (123) satisfy the third condition; The third condition includes: The center coordinates of the positive strain zone (121) are O1 (0, y1), the center coordinates of the transition zone (122) are O2 (r0-R2, h0+R2), and the center coordinates of the negative strain zone (123) are O3 (r0-R3, -h0-R3); The radius of the positive strain zone (121) is R1, the radius of the transition zone (122) is R2, and the radius of the negative strain zone (123) is R3; The contour curve of the positive strain zone (121) satisfies the equation The transition zone (122) contour curve satisfies the equation The contour curve of the negative strain zone (123) satisfies the equation Where h0 is the thickness of the diaphragm at the thinnest point; r0 is the inner diameter of the blind hole.

5. A strain gauge pressure sensor, characterized in that: include: An elastomer as described in any one of claims 1-4; an intermediate layer and a sensitive grid; the sensitive grid comprises a radial resistor and a tangential resistor.

6. A method for processing a strain gauge pressure sensor as claimed in any one of claims 1 to 5, characterized in that: The following steps are involved: S1. Material handling; S2, coating the fusing agent; S3, fusing the steel plate and the foil material to form a composite plate; S4, design elastic strain diaphragm; S6. Processing the strain diaphragm according to the design results; S7, etching the sensitive grid of the Wheatstone bridge; S8. Split the composite plate.

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