CN105172489A - Tire pressure detecting device based on circular ring contact type three-dimensional pressure sensors - Google Patents

Abstract

The invention discloses a tire pressure detecting device based on circular ring contact type three-dimensional pressure sensors. The tire pressure detecting device based on the circular ring contact type three-dimensional pressure sensors comprises a controller, an antenna and the multiple pressure sensors used for measuring the pressure borne by a tire. The pressure sensors are evenly and symmetrically bound to the inner surface of a rim through binding belts. The pressure sensors transmit signals to the antenna after measuring data to be acquired. The antenna is wirelessly connected with the controller. The pressure sensors are circular ring contact type three-dimensional pressure sensors. Each pressure sensor comprises a control unit, a circular ring capacitor unit and a strip-shaped capacitor unit, wherein the circular ring capacitor unit and the strip-shaped capacitor unit are connected with the control unit. According to the tire pressure detecting device based on the circular ring contact type three-dimensional pressure sensors, the multiple tire pressure sensors are arranged on the rim to monitor the pressure borne by all points of the tire, the tire pressure sensors are improved, in this way, pressure measurement precision is improved, and the problem that in the prior art, the measurement precision of a tire pressure sensor is low is solved; the mutual influence of measurement of force on three dimensions is avoided during pressure measurement, measurement precision is improved, all the points of the tire are measured at the same time, and tire pressure hidden dangers are found in time.

Description

Based on the tire pressure detecting device of annulus contact-type 3 D pressure sensor

Technical field

The invention belongs to pressure techniques monitoring field, relate to pressure sensor monitoring direction, be specifically related to a kind of tire pressure detecting device based on annulus contact-type 3 D pressure sensor.

Background technology

Tire pressure monitoring system, by monitoring the change of tyre inner pressure, carrys out the generation of pre-preventing tyre from breaking by early warning, the safety of the stable and driver and crew travelled to protect vehicle.Tire pressure monitoring sensor is then the core component in whole system, and its serviceability directly determines accuracy and the reliability of monitoring system.According to configuring condition, pressure sensor can be divided into active and passive type two kinds.Active sensor needs subsidiary powered battery, to meet the energy demand of working sensor; Passive sensor then relies on external energy coupling and carries out work.

At present, pressure sensor commercial on market is all active, gets up by pressure sensor, power supply, microprocessor and wireless communication module integration packaging, is installed in wheel rim or on cranked tire valve.Due to the mounting means that it is additional in outside, in tyre service, tuning process, easily cause the damage of valve or transmitter module, tire pressure monitoring system was lost efficacy.Secondly, because the tire tube valve setting angle of different wheel rim is when 5-35 degree change, tyre pressure transmitter is also with the change of identical angle, and its angle changes size and be ± 15 degree.But, the angle changing of tyre pressure transmitter is large, its antenna angle changing is after mounting also large, the side-play amount of touch sensor all can be formed with the pressure in the bead of rim under the High Rotation Speed of wheel, pressure sensor take off data is caused to occur error, sensitivity is less than estimated valve, causes signal launch mass to decline simultaneously.

Summary of the invention

According to above the deficiencies in the prior art, the present invention proposes a kind of tire pressure detecting device, by arranging multiple pressure sensor on wheel rim, Real-Time Monitoring tire each point pressure, and pressure sensor is improved, improve pressure measurement accuracy, solve pressure sensor survey precision in prior art low, in pressure, tangential force is on the impact of normal force, when having a pressure survey, three-dimensional force is independent of each other between measuring mutually, improve survey precision, each point of tire is measured, Timeliness coverage tire pressure hidden danger simultaneously.

To achieve these goals, the technical scheme that the present invention takes is: a kind of tire pressure detecting device based on annulus contact-type 3 D pressure sensor, described device comprises controller, the pressure sensor of antenna and multiple measurement tire pressure size, pressure sensor is bundled in the inside face of wheel rim symmetrically by bandage, after pressure sensor measures data to be collected, transmission of signal is to antenna, antenna wireless connection control device, pressure sensor is annulus contact-type 3 D pressure sensor, pressure sensor sensor comprises control unit, the annulus capacitor cell group be connected respectively with control unit and strip capacitor cell group, described annulus capacitor cell group is for surveying the size of tangential force and normal force, described strip capacitor cell group is for measuring the direction of tangential force, described strip capacitor cell group is arranged on the corner of the outer substrate of annulus capacitor cell group.

In said apparatus, described annulus capacitor cell group comprises two to above annulus capacitor cell pair, described annulus capacitor cell is to comprising two annulus capacitor cells, described strip capacitor cell group comprises X-direction differential capacitor unit group and Y-direction differential capacitor unit group, X-direction differential capacitor unit group and Y-direction differential capacitor unit group include two or more and mutually form differential capacitor cell module, the comb teeth-shaped structure that described capacitor cell module is made up of plural strip capacitor cell, each annulus capacitor cell and strip capacitor cell include the drive electrode of top crown and the induction electrode of bottom crown.The induction electrode of described each annulus capacitor cell and drive electrode just to and shape is identical, the drive electrode of described each strip capacitor cell is identical with induction electrode width, the drive electrode length of strip capacitor cell is greater than induction electrode length, the drive electrode length two ends reserved left poor position δ respectively of strip capacitor cell _leftwith right poor position δ _right, b _{0 drives}=b _{0 sense}+ δ _right+ δ _left, wherein b _{0 drives}for the drive electrode length of strip capacitor cell, b _{0 sense}for the induction electrode length of strip capacitor cell, the left poor position δ of described strip capacitor cell _left=right poor position δ _right, and wherein d ₀for elastic medium thickness, G is the modulus of rigidity of elastic medium, τ _maxfor maximum stress value.Described two groups of drive electrodes mutually forming the strip capacitor cell of differential capacitor cell module and induction electrode broad ways are provided with the skew that initially misplaces, and dislocation bias size is identical, direction is contrary.Described annulus capacitor cell group comprises n donut capacitor cell, wherein wherein, a _flatfor the length of parallel plate, r _circlefor the width of annulus capacitor cell annulus, a _{δ circle}electrode separation between adjacent two annulus capacitor cells.The width r of described donut capacitor cell _circlewith the width a of strip capacitor cell ₀equal; Strip capacitor cell electrode separation a _{δ bar}with annulus capacitor cell electrode separation a _{δ circle}equal, the width of described strip capacitor cell wherein, d ₀for elastic medium thickness, E is the Young's modulus of elastic medium, and G is the modulus of rigidity of elastic medium.Described annulus capacitor cell group is connected with control unit by a pig-tail wire with the drive electrode of strip capacitor cell group, the induction electrode of each annulus capacitor cell of described annulus capacitor cell group goes between separately and to be connected with control unit, and described X-direction differential capacitor unit group is connected with control unit respectively by a pig-tail wire with the capacitor cell module induction electrode of Y-direction differential capacitor unit group.

In said apparatus, described controller comprises data statistics unit, data analysis unit and abnormal data unit, data statistics unit carries out adding up the detection data of each pressure sensor and data is classified, then sorted data are delivered to data analysis unit carry out data analysis and mutually compare, thus finding abnormal data stored in abnormal data unit, controller sends alarm signal according to abnormal data.Described bandage is mixed system, and centre is adhesive tape, and both sides are rough strips.Described tire pressure detecting device also comprises connector, and connector is removably connected in the middle of the tire tube valve on pressure sensor and tire, and the pressure sensor laying antenna is fixed together by disjunctor and tire valve, and all the other pressure sensors are placed on wheel rim.

Beneficial effect of the present invention is: arrange on wheel rim in the present invention and installed multiple pressure sensor, to each point pressurized Real-time measuring and analyzing of tire, and Timeliness coverage hidden danger.Pressure sensor of the present invention is on the basis passing through capacitance measurement three-dimensional force, effective usable floor area using flat board alone, and effectively solve three-dimensional force by the method such as differential to influence each other, thus make normal direction and tangential conversion all reach higher linear, precision and sensitivity.Simultaneously in order to ensure the stability that pressure sensor is installed, present invention improves over strap configurations, conveniently laying tighten sensor, and hinder sensor movement to lose, the present invention is highly suitable for work and vehicle travels.

Accompanying drawing explanation

Below the content expressed by this Figure of description and the mark in figure are briefly described:

Fig. 1 is the work structuring block diagram of the specific embodiment of the present invention.

Fig. 2 is the donut skew dislocation areal analysis figure of the specific embodiment of the present invention.

Fig. 3 be the specific embodiment of the present invention for the dislocation of outer donut is to external diameter circle analysis chart.

Fig. 4 is the plane design drawing of the parallel plate capacitor of the specific embodiment of the present invention.

Fig. 5 is the constructional drawing of the drive electrode of the specific embodiment of the present invention.

Fig. 6 is the rectangular coordinate system of the capacity plate antenna plate of the specific embodiment of the present invention.

Fig. 7 is two groups of annulus capacitor bank constructionals drawing of the specific embodiment of the present invention.

Fig. 8 is the initial dislocation figure of the differential strip capacitor cell of the specific embodiment of the present invention.

Fig. 9 is the stressed rear deflection graph of differential strip capacitor cell of the specific embodiment of the present invention.

Figure 10 is the differential schematic diagram of signal that the cell capacitance of the specific embodiment of the present invention is right.

Figure 11 is the plane parallel capacitor cross-section structure of the specific embodiment of the present invention.

Figure 12 is the scheme of installation of pressure sensor on wheel rim of the specific embodiment of the present invention.

Figure 13 is the structural representation of the bandage of the specific embodiment of the present invention.

Figure 14 is the mounting structure schematic diagram of the valve antenna of the specific embodiment of the present invention.

In figure, 1 is upper PCB substrate, and 2 is lower PCB substrate, and 3 is drive electrode Copper Foil, and 4 is induction electrode Copper Foil, and 5 is pressure sensor, and 6 is wheel rim, and 7 is bandage, and 8 is adhesive tape, and 9 is rough strip, and 10 is connector, and 11 is elastic construction, and 12 is antenna.

Detailed description of the invention

Contrast accompanying drawing below, by the description to embodiment, the specific embodiment of the present invention is as the effect of the mutual alignment between the shape of involved each component, structure, each several part and annexation, each several part and principle of work, manufacturing process and operation using method etc., be described in further detail, have more complete, accurate and deep understanding to help those skilled in the art to inventive concept of the present invention, technical scheme.

The invention provides a kind of tire pressure detecting device based on annulus contact-type 3 D pressure sensor, its work structuring block diagram as shown in Figure 1, this detecting device comprises controller, valve antenna 12 and multiple pressure sensor 5, pressure sensor 5 is evenly bundled in wheel rim 6 surface, after pressure sensor 5 measures pressure data on wheel rim 6, transmission of signal is to valve antenna 12, valve antenna 12 is arranged on tire tube valve, facilitates signal transmission, ensure that the accuracy of signal transmission simultaneously.Controller is arranged on operator's compartment, controller receives the data that antenna is sent, the data that each pressure sensor detects have self marker, controller distinguishes the characteristic signal of each pressure sensor, simulate the curve of cyclical fluctuations figure of each pressure sensor, the tire pressure simultaneously contrasting the same time detects data, analyzes accidental data, reminds chaufeur to watch out for tire pressure failure.In addition, pressure sensor provided by the invention is that Touch Mode Capacitive Pressure Sensor can carry out three-dimensional force detection, solves the impact that tangential force produces normal force, improves the sensitivity of sensor in tire pressure detection simultaneously.

Pressure sensor adopts annulus contact-type 3 D pressure sensor, the annulus capacitor cell group that described sensor comprises control unit, be connected respectively with control unit and strip capacitor cell group, described annulus capacitor cell group is for surveying the size of tangential force and normal force, institute's strip capacitor cell group is for measuring the direction of tangential force, and described strip capacitor cell group is arranged on the corner outside substrate annulus capacitor cell group.Annulus capacitor cell group comprises annulus capacitor cell pair more than two, described annulus capacitor cell is to comprising two annulus capacitor cells, described strip capacitor cell group comprises X-direction differential capacitor unit group and Y-direction differential capacitor unit group, X-direction differential capacitor unit group and Y-direction differential capacitor unit group include two or more and mutually form differential capacitor cell module, described capacitor cell module adopts the comb teeth-shaped structure be made up of plural strip capacitor cell, each annulus capacitor cell and strip capacitor cell include the drive electrode of top crown and the induction electrode of bottom crown.The induction electrode of described each annulus capacitor cell and drive electrode just to and shape is identical, the drive electrode of described each strip capacitor cell is identical with induction electrode width, the drive electrode length of strip capacitor cell is greater than induction electrode length, the drive electrode length two ends reserved left poor position δ respectively of strip capacitor cell _leftwith right poor position δ _right, b _{0 drives}=b _{0 sense}+ δ _right+ δ _left, wherein b _{0 drives}for the drive electrode length of strip capacitor cell, b _{0 sense}for the induction electrode length of strip capacitor cell.The left poor position δ of described strip capacitor cell _left=right poor position δ _right, and wherein d ₀for dielectric thickness, G is the modulus of rigidity of elastic medium, τ _ymaxfor maximum stress value.Described two groups of drive electrodes mutually forming the strip capacitor cell of differential capacitor cell module and induction electrode broad ways are provided with the skew that initially misplaces, and dislocation bias size is identical, direction is contrary.Described annulus capacitor cell group comprises n donut capacitor cell, wherein wherein, a _flatfor the length of parallel plate, r _circlefor the width of annulus capacitor cell annulus, a _{δ circle}electrode separation between adjacent two annulus capacitance.Described capacitor cell module adopts comb teeth-shaped structure, and X-direction differential capacitor unit group and Y-direction differential capacitor unit group include m strip capacitor cell, wherein, a _flatfor the length of parallel plate, a _{δ bar}for the electrode separation between adjacent two strip capacitor cells, a ₀the width of strip capacitor cell.The width r of described donut capacitor cell _circlewith the width a of strip capacitor cell ₀equal; Strip capacitor cell electrode separation a _{δ bar}with annulus capacitor cell electrode separation a _{δ circle}equal, the width of described strip capacitor cell wherein, d ₀for dielectric thickness, E is the Young's modulus of elastic medium, and G is the modulus of rigidity of elastic medium.Described annulus capacitor cell group is connected with control unit by a pig-tail wire with the drive electrode of strip capacitor cell group, the induction electrode of each annulus capacitor cell of described annulus capacitor cell group goes between separately and to be connected with control unit, and described X-direction differential capacitor unit group is drawn each via a pig-tail wire respectively with the capacitor cell module induction electrode of Y-direction differential capacitor unit group and is connected with control unit.Described annulus capacitor cell, be respectively equipped with intermediate translator between capacitor cell module and control unit, changer is for arranging voltage or frequency to the transmission coefficient of electric capacity.

Below in conjunction with accompanying drawing 2-11 to derivation of the present invention and principle, to effect and principle of work, manufacturing process and the operation using method etc. of the mutual alignment between each several part shape, structure, each several part and annexation, each several part, be described in further detail.

1.1 capacitance equation and input-output characteristic thereof

The initial capacitance of parallel plate is:

$C_0=\frac{{\mathrm{\ϵ}}_0\·{\mathrm{\ϵ}}_r\·A_0}{d_0}---\left(1\right)$

In formula, ε ₀vacuum medium electric constant is 8.85PF/m, ε _r=2.5 is dielectric relative dielectric constant, A ₀for the initial right opposite of upper bottom crown amasss.D ₀by σ _nexcitation produce relative deformation ε _n=δ _n/ d ₀=σ _n/ E, (1) formula of substitution obtains input-output characteristic

$C_n={\mathrm{\ϵ}}_0\·{\mathrm{\ϵ}}_r\frac{A_0}{d_0(1-{\mathrm{\ϵ}}_n)}={\mathrm{\ϵ}}_0\·{\mathrm{\ϵ}}_r\frac{A_0}{d_0(1-\frac{F_n}{AE})}---\left(2\right)$

The linearity under 1.2 normal stress effects and sensitivity

1.2.1 the normal direction linearity

(2) F in formula _nin the denominator, therefore C _n=f (F _n) relation be nonlinear.Because of the maxim σ in conversion range _nmaxcompared with dielectric resilient constant E, ε _na very little amount, i.e. ε in denominator _n<<1, omits the higher-order shear deformation of more than quadratic power by (2) formula by series expansion, can be reduced to:

$C_n=C_0(1+\mathrm{\&epsiv;})=C_0(1+\frac{F_n}{A\&CenterDot;E})---\left(3\right)$

Visible at C _nwith F _nconversion characteristic in the maximum relative error of the normal direction linearity close to zero.

1.2.2 sensitivity

By the definition of normal direction sensitivity

By (2) formula then

$S_{n2}=\frac{{\mathrm{dC}}_n}{{\mathrm{dF}}_n}=C_0\&CenterDot;\frac{1}{1-2\mathrm{\&epsiv;}}=C_0\&CenterDot;\frac{1}{1-2\frac{F_n}{A\&CenterDot;E}}---\left(4\right)$

Can linear sensitivity be obtained by (3) formula,

S _n1＝C ₀/ _AE＝ε ₀ε _r/d ₀E(5)

S _n2with F _nand become, F _nlarger, S _n2larger, in mild nonlinear in whole conversion characteristic.

Relation between 1.3 tangential displacements and annulus cond payload space

For donut electric capacity to analyzing, as shown in Figure 2, R ₁for exradius, R ₂for inner circle radius, r=annular width=large exradius R ₁-inner circle radius R ₂.To the power F on drive electrode tangent plane _x, cause drive electrode corresponding up and down and induction electrode to produce one and shear dislocation, if d _xfor tangent plane displacement, dislocation area is S _inand S _outward, the initial right opposite of battery lead plate is long-pending should be π (R ₁ ²-R ₂ ²).Fig. 3 is that outer donut electric capacity justifies analysis chart to external diameter, and before and after mobile, two distance of center circle are from being d _x, before and after mobile, the intersection point of two centers of circle and two circles forms a rhombus, can calculate S _outwardarea:

In above formula, there is d _x<<R ₁, so get

By

Will taylor series expansion, and omit high-order term,

In like manner, can know, S _in=2R ₂d _x, so the wrong area of donut electric capacity is S=2R ₁d _x+ 2R ₂d _x.

The capacitance variations of the annulus capacitor cell group under 1.4 hoop-stress τ encourage

Hoop-stress τ does not change the physical dimension parameter A of pole plate ₀, to dielectric thickness d ₀also do not have an impact.But τ _xand τ _ychange the space structure of plane parallel capacitor, between the upper bottom crown faced by forward, there occurs dislocation skew.The dislocation offset d of pole plate under τ effect _x.When τ is zero, the upper/lower electrode of annulus capacitor cell is just right, free area between upper/lower electrode in figure 3, at τ _xunder the effect of dextrad, top crown creates dislocation offset d to the right relative to bottom crown _x, thus make the payload space between bottom crown when calculating electric capacity $A_{\mathrm{\&tau;}}={\mathrm{\&pi;R}}_1^2-{\mathrm{\&pi;R}}_2^2-2R_1{d}_x-2R_2{d}_x,$ Consequent electric capacity is:

$C_{\mathrm{\&tau;}x}=\frac{{\mathrm{\&epsiv;}}_0\&CenterDot;{\mathrm{\&epsiv;}}_r\&CenterDot;\left({\mathrm{\&pi;R}}_1^2-{\mathrm{\&pi;R}}_2^2-2R_1{d}_x-2R_2{d}_x\right)}{d_0}---\left(6\right)$

According to shearing Hook's law

τ _x=γ _x·G＝G·δ _x/d ₀(7)

(7) are substituted into (6) can obtain

$C_{\mathrm{\&tau;}x}=C_0-\frac{{\mathrm{\&epsiv;}}_0\&CenterDot;{\mathrm{\&epsiv;}}_r\&CenterDot;2\left(R_1+R_2\right)d_x}{d_0}=C_0-\frac{{\mathrm{\&epsiv;}}_0\&CenterDot;{\mathrm{\&epsiv;}}_r\&CenterDot;2\left(R_1+R_2\right)F_x}{A_{\mathrm{\&tau;}}G}{C}_0-\frac{2{\mathrm{\&epsiv;}}_0\&CenterDot;{\mathrm{\&epsiv;}}_r{F}_x}{G\mathrm{\&pi;}\left(R_1-R_2\right)}---\left(8\right)$

(8) formula is the input-output characteristic under shearing stress, C _τwith τ _xlinear, its sensitivity

$S_{\mathrm{\&tau;}x}=\frac{{\mathrm{dC}}_{\mathrm{\&tau;}}}{{\mathrm{dF}}_x}=\frac{2{\mathrm{\&epsiv;}}_0\&CenterDot;{\mathrm{\&epsiv;}}_r}{G\mathrm{\&pi;}\left(R_1-R_2\right)}---\left(9\right)$

Tangential sensitivity and R can be found out by formula (9) ₁-R ₂relevant, namely the width of tangential sensitivity and annulus is inversely proportional to, and width more sluggishness is higher.

The design of 2 plate condensers

The design of 2.1 plate condensers

Arrange and the constructional drawing of Fig. 5 drive electrode, at a 10 × 10mm see the electrode plane in Fig. 4 ²substrate on a kind of circular ring type contact parallel plate three-dimensional pressure sensor, the annulus capacitor cell group that sensor comprises control unit, be connected respectively with control unit and strip capacitor cell group, annulus capacitor cell group is for surveying the size of tangential force and normal force, strip capacitor cell group is for measuring the direction of tangential force, and strip capacitor cell group is arranged on the corner outside substrate annulus capacitor cell group.Can use the area of parallel plate by actv. like this, annulus capacitor cell group is paved with whole parallel plate, when measuring three-dimensional force, all work, and strip capacitor cell group effectively make use of annulus capacitor cell group lay after, the space of parallel plate corner, for measuring the direction of three-dimensional force tangential force.The drive electrode of annulus capacitor cell group and induction electrode are all made up of n donut, and n is even number, then form n/2 annulus capacitor cell pair.Hachure part represents the outer mode cross section of wax-loss casting process, and its geometric configuration and size also should keep accurate when mechanical-moulded.

With reference to the rectangular coordinate system of the capacity plate antenna of Fig. 6, coordinate system origin is at the concentric circles initial point of annulus capacitor cell group, x-axis and y-axis are respectively along the diagonal of capacity plate antenna, X-direction differential capacitor unit group comprises X-direction differential capacitor unit group I and X-direction differential capacitor unit group III, X-direction differential capacitor unit group I and X-direction differential capacitor unit group III lay respectively at the positive and negative semiaxis of x-axis and symmetrical along y-axis, Y-direction differential capacitor unit group comprises Y-direction differential capacitor unit group II and Y-direction differential capacitor unit group IV, Y-direction differential capacitor unit group II and Y-direction differential capacitor unit group IV lay respectively at the positive and negative semiaxis of y-axis and symmetrical along x-axis, X-direction differential capacitor unit group I and X-direction differential capacitor unit group III are formed τ _xmake the differential capacitor unit assembly of response, Y-direction differential capacitor unit group II and Y-direction differential capacitor unit group IV are formed τ _ymake the differential capacitor unit assembly of response.

Annulus capacitor cell group comprises n donut capacitor cell, wherein wherein, a _flatfor the length of parallel plate, r _circlefor the width of annulus capacitor cell annulus, a _{δ circle}electrode separation between adjacent two annulus capacitance.Capacitor cell module adopts comb teeth-shaped structure, and X-direction differential capacitor unit group and Y-direction differential capacitor unit group include m strip capacitor cell, wherein, a _{δ bar}for being provided with electrode separation, a between adjacent two strip capacitor cells ₀the width of strip capacitor cell.The width r of donut capacitor cell _circlewith the width a of strip capacitor cell ₀equal; Strip capacitor cell electrode separation a _{δ bar}with annulus capacitance electrode spacing a _{δ circle}equal, the width of described strip capacitor cell wherein, d ₀for dielectric thickness, E is the Young's modulus of elastic medium, and G is the modulus of rigidity of elastic medium.

2.2 pumping signals and system of axes

Annulus capacitor cell is placed in the rectangular coordinate system shown in Fig. 6, three-dimensional simulation puts on the outside face of capacitor plate, the contact application force produced has Fx, Fy and Fz tri-direction components, and the action direction of Fx and Fy is along X-axis and Y-axis, and the action direction of Fz along OZ axle namely direction, normal direction and hoop-stress are a kind of stress tensor, from can the response of output capacitance between the lead-in wire of electrode; Normal stress σ _n=Fn/A, wherein for pole plate normal direction bearing surface, Fn=Fz is normal component; Both side surface produces paired hoop-stress τ _cut=F _cut/ A.

According to the Hooke's law in mechanics of elasticity, σ _nand τ _x, τ _yelastic body all will be made to produce corresponding distortion.Wherein,

${\mathrm{\&sigma;}}_n=E\&CenterDot;{\mathrm{\&epsiv;}}_n=E\&CenterDot;{\mathrm{\&delta;}}_n/d_0=\frac{F_n}{A}$

In formula, E is the Young's modulus GN/m of elastic medium ², G is the modulus of rigidity GN/m of elastic medium ², δ n is the Normal Displacement (unit: μm) of elastic medium, and δ x and δ y is the relative dislocation (unit: μm) of the upper and lower two-plate of annulus capacitor cell, and its sign is pointed to by coordinate axle and determined.

The calculating of 2.3 normal force and tangential force size

Choosing the n-th annulus capacitor cell and the n-th/2 annulus capacitor cell, by setting up annulus capacitor cell, composition set of equations being calculated, as shown in Figure 7.If after battery lead plate is subject to normal direction and tangential incentive action, if the output capacitance of the n-th annulus capacitor cell is C ₁, n/2 annulus capacitor cell output capacitance is C ₂, tangential displacement is d _x, the capacitance pole distance of normal direction is d _n, S ₁₀the right opposite initial for outer shroud amasss, S ₂₀the right opposite initial for inner ring amasss.

$C_1=\frac{\mathrm{\&epsiv;}\left(S_{10}-S1\right)}{d_n}=\frac{\mathrm{\&epsiv;}\left({\mathrm{\&pi;R}}_1^2-{\mathrm{\&pi;R}}_2^2\right)}{d_n}-\frac{\mathrm{\&epsiv;}\left(2R_1{d}_x+2R_2{d}_x\right)}{d_n}---\left(10\right)$

$C_2=\frac{\mathrm{\&epsiv;}\left(S_{20}-S2\right)}{d_n}=\frac{\mathrm{\&epsiv;}\left({\mathrm{\&pi;r}}_1^2-{\mathrm{\&pi;r}}_2^2\right)}{d_n}-\frac{\mathrm{\&epsiv;}\left(2r_1{d}_x+2r_2{d}_x\right)}{d_n}---\left(12\right)$

Will $\left(10\right)-\left(11\right)*\frac{R_1+R_2}{r_1+r_2}$ Obtain:

$C_1-C_2*\frac{R_1+R_2}{r_1+r_2}=\frac{\mathrm{\&epsiv;}\mathrm{\&pi;}\left(R_1^2-R_2^2\right)}{d_n}-\frac{R_1+R_2}{r_1+r_2}*\frac{\mathrm{\&epsiv;}\mathrm{\&pi;}\left(r_1^2-r_2^2\right)}{d_n}$

If in above formula $\frac{R_1+R_2}{r_1+r_2}=K,$ Then $d_n=\frac{\mathrm{\&epsiv;}\left(S_{10}-{\mathrm{KS}}_{20}\right)}{C_1-{\mathrm{KC}}_2}$

According to $d_n=d_0-\mathrm{\&Delta;}d=d_0(1-\frac{F_n}{E\&CenterDot;S_0})$

Known: $F_n=\frac{\left(d_n-d_0\right)E\&CenterDot;S_0}{d_0}$

By above-mentioned by (10) * C ₂-(11) * C ₁obtain:

$d_x=\frac{C_2{S}_{10}-C_1{S}_{20}}{2C_2\left(R_1+R_2\right)-2C_1\left(r_1+r_2\right)};$

By $\mathrm{\&gamma;}=\frac{\mathrm{\&tau;}}{G}=\frac{F_{\mathrm{\&tau;}}}{G\&CenterDot;S_0}=\frac{d_x}{d_0}=\frac{C_2{S}_{10}-C_1{S}_{20}}{d_{0}2C_2\left(R_1+R_2\right)-d_{0}2C_1\left(r_1+r_2\right)},$ So F _τfor

$F_{\mathrm{\&tau;}}=\frac{\left(C_2{S}_{10}-C_1{S}_{20}\right)\&CenterDot;G\&CenterDot;S_0}{d_{0}2C_2\left(R_1+R_2\right)-d_{0}2C_1\left(r_1+r_2\right)}$

The direction determining of 2.4 tangential forces

2.4.1 strip capacitor cell group shape structure and parameter design

In order to realize τ _xand τ _ybetween tangential response mutually do not have an impact, drive electrode length two ends reserved difference position δ ₀, therefore _{b0 drives}=b _{0 end}+ 2 δ ₀, wherein at b _{0 drives}two ends length is reserved should be ensured in theory ${\mathrm{\&delta;}}_0\&GreaterEqual;d_0\&CenterDot;\frac{{\mathrm{\&tau;}}_{y\max }}{G},$ Its computing value is ${10}^{-5}\&times;\frac{70\&times;{10}^3}{2.4\&times;{10}^6}=2.9\&times;{10}^{-8}m={10}^{-2}um<<1um,$ Therefore should b be ensured in technique _{0 drives}-b _{0 end}>=0.01mm.In order to realize τ _xand τ _ydo not have an impact to the response of normal direction electric capacity, the drive electrode of each strip capacitor cell and induction electrode arrange certain dislocation in floor plan and offset, on by differential elimination impact each other.

As shown in Figure 5, in figure, four dashed rectangle are the benchmark of induction electrode on bottom crown, get the position of induction electrode in lower floor's PCB substrate as reference, then the layout of drive electrode in the PCB substrate of upper strata should with PCB substrate edge line for benchmark.Each strip capacitor cell comprises the drive electrode of top crown and the induction electrode of bottom crown, if often root strip capacitor cell is wide is a ₀, the groove width between two strip capacitor cells is a _δ, then the pitch of every root strip capacitor cell is a ₀+ a _δ.τ can be ensured like this when method of calculation exports response to electric capacity _xand τ _ythe response of normal direction electric capacity is not had an impact.And put they and geometry datum line differential apart from being δ ₀(0.1mm), to ensure that X-direction differential capacitor unit group I and X-direction differential capacitor unit group III produce τ _xdifferential capacitor export response, Y-direction differential capacitor unit group II and Y-direction differential capacitor unit group IV then only produce τ _ydifferential capacitor response, an initially dislocation skew δ is set _x0, its value should ensure its computing value and δ ₀similar, its skew that initially misplaces all arranges δ _x0=δ _y0=0.01mm, to ensure that four capacitor cells are at τ _xand τ _ytwo groups of differential capacitors pair can be produced under tangential excitation.

In Fig. 8, a pair electric capacity C _land C _relectrode size a ₀, b ₀, d ₀all identical, initial dislocation skew δ ₀also identical, difference is left side cond C _lupper strata δ ₀wedge angle be oriented to+OX, and the right cond C _rupper strata δ ₀wedge angle sensing-OX.Work as τ _xwhen=0, $C_L=C_R=C_{\mathrm{\&tau;}0}=C_0-\frac{{\mathrm{\&epsiv;}}_0\&CenterDot;{\mathrm{\&epsiv;}}_r\&CenterDot;\left({\mathrm{\&delta;}}_0\right)\&CenterDot;b_0}{d_0},$ Namely the electric capacity in figure corresponding to dash area.On this basis, as generation ± δ under-Fx excitation _xdislocation skew, formed as shown in Figure 9 electric capacity increase and decrease effect,

$C_L=\frac{{\mathrm{\&epsiv;}}_0\&CenterDot;{\mathrm{\&epsiv;}}_r\&CenterDot;b_0\&CenterDot;(a_0-{\mathrm{\&delta;}}_0\&PlusMinus;{\mathrm{\&delta;}}_x)}{d_0}---\left(12\right)$

In Fig. 9, C _land C _rdifferential capacitor is to same τ _xby generation ± δ _xwith ± △ C _τresponse, δ ₀size should meet desirable δ ₀=10 μm, thus, formula (8) can be revised as

$C_{\mathrm{\&tau;}x}=C_{\mathrm{\&tau;}0}\&PlusMinus;\frac{{\mathrm{\&epsiv;}}_0\&CenterDot;{\mathrm{\&epsiv;}}_r}{{\mathrm{Ca}}_0}{F}_x---\left(13\right)$

In formula, for initial capacitance when shearing stress is zero, (13) formula is shearing stress input-output characteristic, C _{τ x}with F _xlinear relationship, and its sensitivity

By formula (13) known a ₀less, the sensitivity of hoop-stress response is larger, therefore capacitor cell of the present invention adopts the strip capacitor cell group be made up of multiple strip electric capacity.

2.4.2 hoop-stress direction calculating

C _ito C _iIand C _iIIto C _iVtwo can be realized to differential combination, the differential schematic diagram of the signal that the cell capacitance as Figure 10 is right, through differential technique process, the overall response of differential output

$O_{\mathrm{\&tau;}x}=\frac{2{\mathrm{mK\&epsiv;}}_0\&CenterDot;{\mathrm{\&epsiv;}}_r}{a_{0}G}{F}_x$

In formula, no matter be normal direction excitation F _nor tangentially encourage F _yall not to O _τhave an impact, namely automatically eliminate σ _nand τ _yto τ _xthe coupling of total output or interference.Comprise at signal because every in the computing of subtracting each other, equivalent and the same capacitance variations met are eliminated all automatically.And F _yand F _xto σ _ninterference by upper electrode at b ₀direction increases geometrical length 2 δ ₀eliminate.

In like manner,

According to O _{τ x}and O _{τ y}value calculate the direction of tangential force.

2.4 main material selection and characteristic parameter thereof

The section of structure of plane parallel capacitor is similar to sandwich construction as shown in figure 11.As shown in Figure 11,1 is upper PCB substrate, and 2 is lower PCB substrate, and 3 is drive electrode, and 4 is induction electrode.Pole plate is apart from d ₀=0.1mm, upper and lower base plate inner space, except copper foil electrode, is PDMS (polydimethyl diloxanes) the superlastic dielectric with cire-perdue process filling.Its machinery and physical property parameter are Young's modulus E=6.2MPa, and its shear modulus is G=4.1MPa, relative permittivity ε during dielectric polarization _γ=2.5.Because E and G of medium is much smaller than the elastic modulus E of copper _copper=103GPa, therefore the distortion of capacitor internal medium under state of stress is much larger than the distortion of pole plate.

2.5 contact conductor designs

Be that drive electrode or induction electrode all need to have pig-tail wire, consider that each drive electrode is all ground connection in signal level, therefore drive electrode only need share same pig-tail wire.Annulus capacitor cell group is connected with control unit by a pig-tail wire with the drive electrode of strip capacitor cell group, each annulus of described annulus capacitor cell group goes between separately and to be connected with control unit, control unit calculates according to the output valve independent assortment of each annulus, carry out being averaging the size and normal force size that draw tangential force afterwards, when accuracy requirement is not high, annulus capacitor cell group can only select two optimum annulus to draw 2 lead-in wires, obtains d by these two annulus _xand d _n, thus draw size and the normal force size of tangential force; X-direction differential capacitor unit group and Y-direction differential capacitor unit group are drawn each via a pig-tail wire respectively and are connected with control unit, for calculating the direction of tangential force.Be provided with intermediate translator between described control unit and capacitor cell, changer is for arranging voltage or frequency to the transmission coefficient of electric capacity.Whole capacitance component has at least 7 pins and draws from the side of planar package, so that whole assembly top and bottom outside face can contact with measuring object easily.

The present invention, under the support of new material and new process, completes the design of a kind of novel three-dimensional power sensitization capacitance combination.At 10 × 10mm ²bearing surface on, be no matter normal direction or tangential, all can transmit stress more uniformly to medium.In the contact of non-coplanar force and sensor surface, external force only has 1, and can obtain the information of normal direction Fn to electric capacity summation, namely whole battery lead plate is all to asking Fn to contribute, and can obtain F again simultaneously _xand F _yinformation, thus complete description three-dimensional force, can improve the normal direction sensitivity and tangential sensitivity and maximum linear error once changed by design parameters.

In order to better be applicable to life and tire detection, can also install the signal monitoring devices such as Temperature Humidity Sensor in pressure sensor, pressure sensor provided by the invention mainly focuses on pressure survey, improves tonometric precision.But, when wheel stationary or motion time, the right opposite up and down of wheel is pressure maximum point and smallest point, stressed difference, a pressure sensor 5 can not detect in time accurately, if there is the situation of slow gas leakage, tire pressure detects needs a period of time just can detect, potential danger will be brought like this to navigating mate, so, the present invention detects the accuracy of data in order to improve tire pressure, multiple pressure sensor has been installed, preferred even number pressure sensor 5, the schematic diagram of pressure sensor on wheel rim as shown in figure 12, pressure sensor is arranged on wheel rim 6 symmetrically, wheel rim 6 is fixed on inner by bandage 7 tighten, the tidal data recovering of pressure sensor 5 is to valve antenna place, controller is sent to through antenna, by controller Treatment Analysis data.Because wheel rim 6 inside face is smooth, so use viscous friction bandage 7, bandage 7 comprises adhesive tape 8 and rough strip 9, adhesive tape 8 is positioned at the middle part of bandage, rough strip is positioned at the both sides of adhesive tape 8, pressure sensor is placed in adhesive tape 8, pressure sensor is sticked on wheel rim 6 by adhesive tape 8, rough strip 9 prevents the motion of pressure sensor, prevent the motion of pressure sensor 5, because pressure sensor volume is little, so can ensure to be fixed in bandage 7, the structural representation of bandage 7 as shown in figure 13.

Wheel rim 6 is metals that solid hardness is large, has very strong interference to signal transmission, thus in the present invention preferably by signal transmission astronomical cycle at tire tube valve place, increase signal transmission performance.When changeing tire to prevent installation, to friction and the accidental injury of the antenna of tire pressure detecting device, connector 10 is provided with in the end of pressure sensor 5 in the present invention, tire tube valve is facilitated to be connected and fixed the antenna 12 of pressure sensor 5, the sensor at tire tube valve place is provided with connector 10, other sensors are not arranged on tire tube valve place, do not need connector 10 is installed, connector 10 is that detouchable is arranged on pressure sensor 5, connector 10 is provided with an elastic construction 11, elastic construction 11 is provided with tapped bore, by tapped bore by connector 10, sensor 5 and tire tube valve are fixed together, antenna 12 is fixed on sensor 5, by antenna 12, signal transmission is gone out, each pressure sensor away from tire tube valve is also the miniature antenna with transmission of signal, the antenna 12 just connecting tire tube valve is signals that main aerial receives all the sensors inside antenna, pass together with its own signal, Signal reception channel is provided with in antenna 12, the sensor 5 that can receive away from tire tube valve detects data and is forwarded to controller, the mounting structure schematic diagram of valve antenna 12 as shown in figure 14.

Multiple pressure sensor 5 is owing to evenly laying, so should be substantially equal on the data theory of the pressure sensor of symmetric points, tire pressure take off data analyzed from multiple directions by controller: the detection data plot simulating each pressure sensor, all tire pressures of more same time detect data, the relatively data of symmetric points place pressure sensor, analyze data from multiple directions and show that abnormal data display alarm signal is to telltale, reminds chaufeur to watch out for tire pressure failure, processes in time.Data statistics unit, data analysis unit and abnormal data unit is provided with in controller, data statistics unit carries out adding up the detection data of each pressure sensor and data is classified, then sorted data are delivered to data analysis unit carry out data analysis and mutually compare, thus finding abnormal data stored in abnormal data unit, controller sends alarm signal according to abnormal data.

Above by reference to the accompanying drawings to invention has been exemplary description; obvious specific implementation of the present invention is not subject to the restrictions described above; as long as have employed the improvement of the various unsubstantialities that method of the present invention is conceived and technical scheme is carried out; or design of the present invention and technical scheme directly applied to other occasion, all within protection scope of the present invention without to improve.The protection domain that protection scope of the present invention should limit with claims is as the criterion.

Claims (10)

1. the tire pressure detecting device based on annulus contact-type 3 D pressure sensor, it is characterized in that, described device comprises controller, the pressure sensor of antenna and multiple measurement tire pressure size, pressure sensor is bundled in the inside face of wheel rim symmetrically by bandage, after pressure sensor measures data to be collected, transmission of signal is to antenna, antenna wireless connection control device, pressure sensor is annulus contact-type 3 D pressure sensor, pressure sensor sensor comprises control unit, the annulus capacitor cell group be connected respectively with control unit and strip capacitor cell group, described annulus capacitor cell group is for surveying the size of tangential force and normal force, described strip capacitor cell group is for measuring the direction of tangential force, described strip capacitor cell group is arranged on the corner of the outer substrate of annulus capacitor cell group.

2. tire pressure detecting device according to claim 1, it is characterized in that, described annulus capacitor cell group comprises two to above annulus capacitor cell pair, described annulus capacitor cell is to comprising two annulus capacitor cells, described strip capacitor cell group comprises X-direction differential capacitor unit group and Y-direction differential capacitor unit group, X-direction differential capacitor unit group and Y-direction differential capacitor unit group include two or more and mutually form differential capacitor cell module, the comb teeth-shaped structure that described capacitor cell module is made up of plural strip capacitor cell, each annulus capacitor cell and strip capacitor cell include the drive electrode of top crown and the induction electrode of bottom crown.

3. tire pressure detecting device according to claim 2, it is characterized in that, the induction electrode of described each annulus capacitor cell and drive electrode just to and shape is identical, the drive electrode of described each strip capacitor cell is identical with induction electrode width, the drive electrode length of strip capacitor cell is greater than induction electrode length, the drive electrode length two ends reserved left poor position δ respectively of strip capacitor cell _leftwith right poor position δ _right, b _{0 drives}=b _{0 sense}+ δ _right+ δ _left, wherein b _{0 drives}for the drive electrode length of strip capacitor cell, b _{0 sense}for the induction electrode length of strip capacitor cell, the left poor position δ of described strip capacitor cell _left=right poor position δ _right, and wherein d ₀for elastic medium thickness, G is the modulus of rigidity of elastic medium, τ _maxfor maximum stress value.

4. tire pressure detecting device according to claim 2, it is characterized in that, described two groups of drive electrodes mutually forming the strip capacitor cell of differential capacitor cell module and induction electrode broad ways are provided with the skew that initially misplaces, and dislocation bias size is identical, direction is contrary.

5. tire pressure detecting device according to claim 2, is characterized in that, described annulus capacitor cell group comprises n donut capacitor cell, wherein wherein, a _flatfor the length of parallel plate, r _circlefor the width of annulus capacitor cell annulus, a _{δ circle}electrode separation between adjacent two annulus capacitor cells.

6. tire pressure detecting device according to claim 2, is characterized in that, the width r of described donut capacitor cell _circlewith the width a of strip capacitor cell ₀equal; Strip capacitor cell electrode separation a _{δ bar}with annulus capacitor cell electrode separation a _{δ circle}equal, the width of described strip capacitor cell wherein, d ₀for elastic medium thickness, E is the Young's modulus of elastic medium, and G is the modulus of rigidity of elastic medium.

7. tire pressure detecting device according to claim 2, it is characterized in that, described annulus capacitor cell group is connected with control unit by a pig-tail wire with the drive electrode of strip capacitor cell group, the induction electrode of each annulus capacitor cell of described annulus capacitor cell group goes between separately and to be connected with control unit, and described X-direction differential capacitor unit group is connected with control unit respectively by a pig-tail wire with the capacitor cell module induction electrode of Y-direction differential capacitor unit group.

8. tire pressure detecting device according to claim 1, it is characterized in that, described controller comprises data statistics unit, data analysis unit and abnormal data unit, data statistics unit carries out adding up the detection data of each pressure sensor and data is classified, then sorted data are delivered to data analysis unit carry out data analysis and mutually compare, thus finding abnormal data stored in abnormal data unit, controller sends alarm signal according to abnormal data.

9. tire pressure detecting device according to claim 1, is characterized in that, described bandage is mixed system, and centre is adhesive tape, and both sides are rough strips.

10. tire pressure detecting device according to claim 1, it is characterized in that, described tire pressure detecting device also comprises connector, connector is removably connected in the middle of the tire tube valve on pressure sensor and tire, the pressure sensor laying antenna is fixed together by disjunctor and tire valve, and all the other pressure sensors are placed on wheel rim.