CN204788986U - Tire homogeneity parameter measurement device - Google Patents

Abstract

The utility model relates to a tire homogeneity parameter measurement device, including the load wheel, sensor and sensing system signal processor, the load wheel is close to the tire as the driven camber of wheels of tire, the upper and lower both ends at the load wheel are established as the both ends strong point of load wheel to the sensor, radial force between sensor collection load wheel and the testing tire and yawing force erupt simultaneously and give sensing system signal processor, the sensor includes that ring electricity n holds unique tuple and strip electric capacity unique tuple, ring electric capacity unique tuple is used for surveying the size of tangential force and normal force, strip electric capacity unique tuple is used for measuring the direction of tangential force, the utility model discloses a tire homogeneity detection device measures radial force and yawing force between tire and the load round, through these two parameter analysis radial force fluctuations, yawing force fluctuation, tapering, off tracking, radial missing (top, central authorities, bottom), lateral deviation (top, bottom) isoparametric, scientifically calibrates the inhomogeneities of tire.

Description

Tyre evenness parameter measuring apparatus

Technical field

The invention belongs to automobile equipment detection technique field, be specifically related to a kind of tyre evenness parameter measuring apparatus.

Background technology

Tyre evenness refer to tire when by radial load and High Rotation Speed tire force of periphery fluctuation characteristic both unevenness.According to mechanics principle and mechanical motion principle, doughnut can cause tire to produce radial force and the side force of alternation fluctuation due to the uneven microstructure of internal material, the uneven of form factor and the error etc. in fitted position under rotational case of running at high speed, thus the vibration causing automobile upper and lower, left and right sideslip, noise etc., affect the maneuverability of automobile, comfort level or smoothness.Serious meeting damage car parts, even can cause traffic hazard.

The radial force obtained by measuring wheel tyre uniformity pick-up unit and side force, by parameters such as these two fluctuations of Parameter analysis radial force, side force fluctuation, tapering, sideslip, radial missing (top, central authorities, bottom), lateral deviations (top, bottom), scientifically calibrate the unevenness of tire, and guide the nonuniformity correction to tire, make the unevenness of tire reach minimum value, thus reach the object of improvement, raising tire quality.

Summary of the invention

In order to overcome the deficiencies in the prior art, the invention provides a kind of tyre evenness parameter measuring apparatus, by the up and down end points place of sensor setting at loading wheel, measure tire to the side force of loading wheel and radial force, analyzed the homogeneity of tire by the parameter such as taper effect, angular effect, radial force fluctuation, side force fluctuation analyzing radial force and side force.

Technical scheme of the present invention is: a kind of tyre evenness parameter measuring apparatus, comprise loading wheel, sensor and sensor-based system signal processor, loading wheel as the engaged wheel curved surface of tire near tire, sensor is located at the two ends up and down of loading wheel as the two ends strong point of loading wheel, sensor gathers radial force between loading wheel and testing tire and side force and sends to sensor-based system signal processor, sensor comprises annulus capacitor cell group and strip capacitor cell group, described strip capacitor cell group is arranged on the corner of the outer substrate of annulus capacitor cell group, 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.

Tyre evenness pick-up unit also comprises main shaft and upper and lower wheel rim, the dead in line of upper and lower wheel rim and main shaft, lower wheel rim and integrated spindle axis, upper wheel rim is up and down can free movement, the axis being parallel of loading wheel axis and main shaft, tire clamping is between upper and lower wheel rim.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 are provided with the skew that initially misplaces in the width direction, 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 electric capacity.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 elastic medium thickness, E is the Young modulus of elastic medium, and G is the modulus of rigidity of elastic medium.Described annulus capacitor cell group is connected with sensor-based system signal processor by an extension line 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 sensor-based system signal processor, and described X-direction differential capacitor unit group is connected with sensor-based system signal processor respectively by an extension line with the capacitor cell module induction electrode of Y-direction differential capacitor unit group.Described annulus capacitor cell, be respectively equipped with intermediate translator between capacitor cell module and sensor-based system signal processor, intermediate translator is for arranging voltage to electric capacity or frequency to the transmission coefficient of electric capacity.

The present invention has following good effect: the radial force between tyre evenness pick-up unit measurement driving tyre of the present invention and engaged wheel loading wheel and side force, by parameters such as these two fluctuations of Parameter analysis radial force, side force fluctuation, tapering, sideslip, radial missing (top, central authorities, bottom), lateral deviations (top, bottom), scientifically calibrate the unevenness of tire, and guide the nonuniformity correction to tire, make the unevenness of tire reach minimum value, thus reach the object of improvement, raising tire quality.In addition, 2 D force sensor of the present invention can simultaneous measurement method to power and tangential force, highly sensitive, pole plate utilization ratio is high, and whole annulus capacitor cell group is all made contributions to normal force, and has good dynamic property.

Accompanying drawing explanation

Fig. 1 is the donut skew dislocation areal analysis figure of the specific embodiment of the present invention.

Fig. 2 be the specific embodiment of the present invention for the dislocation of outer donut is to external diameter circle analysis chart.

Fig. 3 is the plane design drawing of the parallel plate capacitor of the specific embodiment of the present invention.

Fig. 4 is the structural drawing of the drive electrode of the specific embodiment of the present invention.

Fig. 5 is the rectangular coordinate system of the capacity plate antenna plate of the specific embodiment of the present invention.

Fig. 6 is two groups of annulus capacitance group structural drawing of the specific embodiment of the present invention.

Fig. 7 is the initial dislocation figure of the differential strip capacitor cell of the specific embodiment of the present invention.

Fig. 8 is the stressed rear deflection graph of differential strip capacitor cell of the specific embodiment of the present invention.

Fig. 9 is the differential schematic diagram of signal that the cell capacitance of the specific embodiment of the present invention is right.

Figure 10 is the structural drawing of the tyre uniformity test device of the specific embodiment of the present invention.

Figure 11 is the tyre uniformity test force analysis figure of the specific embodiment of the present invention.

Wherein, wheel rim, 4 tires, 5 loading wheels, 6 sensors on 1 main shaft, 2 times wheel rims, 3.

Embodiment

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.

Main thought of the present invention is: tire is a kind of flexible rotary body of annular tubular section, radial-ply tyre be by multilayer with the rubber preformed material of all-steel cord, compounded rubber preformed material through laminating, shaping and sulfuration is qualitative forms, so just uneven the or mass eccentricity etc. of generation material causes unevenness.According to relevant mechanics principle, there is to a certain degree uneven tire, a lot of motion feature can be shown, as the existence friction in all directions on tire and ground, tire bear the characteristics such as the change of load, the taper effect causing tire modification, angular effect in dynamic movement process.

Taper effect refers to the not side force of the reindexing skew because tire rotation direction changes.Angular effect refers to along with tire rotation direction changes and the skew of the side force of reindexing.In order to calculate taper effect and angular effect, the side force mean value of tire under rotating forward, Reversion must be obtained, namely side force skew and the skew of reversion side force is rotated forward, these two indexs obtain the intermediate data result of taper effect and angular effect, equally also using a yardstick as homogeneity.The radial force of tire is fluctuated, the analysis of side force fluctuation also will specific to rotating forward situation and Reversion, simultaneously, 1 ~ 10 subharmonic due to radial force fluctuation, side force fluctuation is the principal ingredient forming the fluctuation of radial force fluctuation side force, and the size (amplitude) of component shared by each harmonic wave is also by the speciality of reflection tire, be the parameter that homogeneity is investigated equally.For in each harmonic that radial force fluctuation and side force are fluctuated, first harmonic component has more representativeness, and its amplitude size have impact on the size of fluctuation greatly.

Radial force fluctuation refers to the peak-to-peak value (unit: N) of tire radial force in one or more rotation periods of forward or reverse; Radial force 1 ~ 10 subharmonic (RFH1 ~ RFH10) refers to that the relation curve testing tire radial force and the tire rotation angle obtained by fluctuation is a tuning curve, to the stressed waveform Fourier analysis of the radial force in one or more rotation periods of tire forward or reverse, they are resolved into 1 time to 10 subharmonic, 1 composition of its Central Plains ripple is called first harmonic (RFH1) or is first-harmonic (unit: N); Side force fluctuation (LFV) refers to the peak-to-peak value (unit: N) of tire lateral force in one or more rotation periods of forward or reverse; Side force 1 ~ 10 subharmonic (LFH1 ~ LFH10) refers to that the relation curve testing side force of tire and the tire rotation angle obtained by fluctuation is a tuning curve, to the stressed waveform Fourier analysis of the side force in one or more rotation periods of tire forward or reverse, they are resolved into 1 time to 10 subharmonic, 1 composition of its Central Plains ripple is called first harmonic (RFH1) or is first-harmonic (unit: N); Side force skew (LSFT) refers to the mean value (unit: N) of tire lateral force integration in one or more rotation periods of forward or reverse.

As shown in Figure 10, be the structural representation of tyre evenness pick-up unit of the present invention, the dead in line of upper and lower wheel rim 2 and main shaft 1, lower wheel rim 2 and main shaft 1 one, upper wheel rim 3 is up and down can free movement.The axis being parallel of loading wheel 5 axis and main shaft 1, tests front upper wheel rim 3, loading wheel 5 away from main shaft 1, is in respective origin position respectively.During test, tire is loaded on lower wheel rim 2, and upper wheel rim 3 declines, and upper and lower wheel rim relative position is locked and clamps tire 4, and tire 4 is inflated, and makes tire 4 internal pressure keep constant.Tire 4 relies on charge pressure and upper and lower wheel rim to fix, and revolves in shape process the relative dislocation that tire 4 and upper and lower wheel rim can not occur like this at main shaft 1.Loading wheel 5 level left near and contact tire 4, apply constant pressure to tire 4, tire 4 and loading wheel 5 keep constant rotational speed to rotate by friction force, and the relative position of main shaft 1 and tire 4 is constant, then main shaft 1 and tire 4 rotate with same angular velocity.

Stressed between tire 4 and loading wheel 5 is analyzed, comprise radial force, side force and tangential friction force, due to the driving force that friction force is loading wheel 5, so do not study here, because the surface of contact center of radial force, main shaft 1 axis, loading wheel 5 axis, force snesor 6 plane and tire 4 and loading wheel 5 is all in same plane, so establish if the normal force system of the two dimension of figure is to do power analysis.

Two-dimensional quadrature force cell 6 arranges two end points places of loading wheel 5 in the drawings, and be the two ends strong point of loading wheel 5 axis, loading wheel 5 applies load and the two axis being parallel to tire 4, and sensor 6 is as shown in figure 11 stressed with tire 4, the radial force F of tire 4 _requaling the X-direction power sum of upper and lower force cell 6, is also F ₃+ F ₅, side force F ₁equaling the Y-direction power sum of lower sensor 6, is also F ₂+ F ₄.

After several rotation periods, loading wheel 5 and tire 4 stop operating, tire 4 is exitted, upper wheel rim 3 and loading wheel 5 level return to reset position, the all data collected calculate by sensor-based system signal processor, obtain every uniformity index of detected tyre, complete the test of homogeneity.

Sensor of the present invention comprises annulus capacitor cell group 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 are provided with the skew that initially misplaces in the width direction, 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 modulus of elastic medium, and G is the modulus of rigidity of elastic medium.Described annulus capacitor cell group is connected with sensor-based system signal processor by an extension line 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 sensor-based system signal processor, and described X-direction differential capacitor unit group is drawn each via an extension line respectively with the capacitor cell module induction electrode of Y-direction differential capacitor unit group and is connected with sensor-based system signal processor.Described annulus capacitor cell, be respectively equipped with intermediate translator between capacitor cell module and sensor-based system signal processor, transducer is for arranging voltage or frequency to the transmission coefficient of electric capacity.

Below in conjunction with accompanying drawing 1-9 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 ₀excitation produce relative deformation ε _n=δ _n/ d ₀=σ _n/ E, (1) formula of substitution obtains input-output characteristic

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

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 maximal value 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 capacitor useful area

For donut electric capacity to analyzing, as shown in Figure 1, 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. 2 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:

S _outward=S _{fan β}-S _{fan α}+ S _rhombus

$\begin{array}{c}=\frac{1}{2}{R_1}^2\left(2\mathrm{\&pi;}-2\mathrm{\&alpha;}\right)-\frac{1}{2}{R_1}^2*2\mathrm{\&alpha;}+4*\frac{1}{2}*\frac{d_x}{2}{R}_1\sin \mathrm{\&alpha;}\\ ={{\mathrm{\&pi;R}}_1}^2+2{R_1}^2\mathrm{\&alpha;}+d_x{R}_1\sin \mathrm{\&alpha;}\\ ={{\mathrm{\&pi;R}}_1}^2-2{R_1}^2\arccos \frac{d_x}{2R_1}+d_x{R}_1\sqrt{1-\frac{d_x^2}{4R_1^2}}\end{array}$

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 tangential stress τ excitations

Tangential 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 _τchange 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 fig. 2, at τ _xunder the effect of dextrad, top crown creates dislocation offset d to the right relative to bottom crown _x, thus make the useful area between bottom crown when calculating electric capacity consequent electric capacity is:

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

According to shearing Hooke's law

τ _x＝γ _x·G＝G·δ _x/d ₀(7)

(7) are substituted into (6) can obtain

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

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

$S_{\mathrm{\&tau;}x}=\frac{{\mathrm{dC}}_{\mathrm{\&tau;}}}{{\mathrm{dF}}_x}=\frac{2{\mathrm{\&epsiv;}}_0\&CenterDot;{\mathrm{\&epsiv;}}_r}{G\mathrm{\&pi;}(R_1-R_2)}---\left(10\right)$

Tangential sensitivity and R can be found out by formula (10) 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 structural drawing of Fig. 4 drive electrode, at a 10 × 10mm see the electrode plane in Fig. 3 ²substrate on a kind of circular ring type contact parallel-plate three-dimensional pressure sensor, the annulus capacitor cell group that sensor comprises sensor-based system signal processor, be connected respectively with sensor-based system signal processor 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.Effectively can use the area of parallel-plate 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. 5, 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 combination 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 combination 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 modulus of elastic medium, and G is the modulus of rigidity of elastic medium.

2.2 pumping signals and coordinate system

Annulus capacitor cell is placed in the rectangular coordinate system shown in Fig. 5, three-dimensional simulation puts on the outside surface of capacitor plate, the contact acting force produced has Fx, Fy and Fz tri-durection 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 tangential 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 stress surface, Fn=Fz is normal component; Both side surface produces paired tangential stress τ _cut=F _cut/ A.

According to the Hooke's law in 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 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 axis 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 system of equations being calculated, as shown in Figure 6.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.

Will obtain:

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

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

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

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

Above-mentioned is incited somebody to action 1. * C ₂-2. * C ₁obtain:

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

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

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

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 b _{0 drives}=b _{0 end}+ 2 δ ₀, wherein at b _{0 drives}two ends length is reserved should be ensured in theory its calculated 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 4, 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 computing method 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 _xo, its value should ensure its calculated value and δ ₀similar, its skew that initially misplaces all arranges δ _xo=δ _yo=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. 7, 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 capacitor C _lupper strata δ ₀wedge angle be oriented to+OX, and the right capacitor C _rupper strata δ ₀wedge angle sensing-OX.Work as τ _xwhen=0, namely the electric capacity in figure corresponding to dash area.On this basis, as at-F _xlower generation ± the δ of excitation _xdislocation skew, formed as shown in Figure 8 electric capacity increase and decrease effect,

$C_L=\frac{{\mathrm{\&epsiv;}}_0\&CenterDot;{\mathrm{\&epsiv;}}_r\&CenterDot;b_0\&CenterDot;(a_0-{\mathrm{\&delta;}}_0\&PlusMinus;{\mathrm{\&delta;}}_x)}{d_0}---\left(13\right)$

In Fig. 8, C _land C _rdifferential capacitor is to same τ _xby generation ± δ _xwith ± Δ C _τresponse, δ ₀size should meet desirable δ ₀=10 μm, thus, formula (11) can be revised as

$C_{\mathrm{\&tau;}x}=C_{\mathrm{\&tau;}0}\&PlusMinus;\frac{{\mathrm{\&epsiv;}}_0\&CenterDot;{\mathrm{\&epsiv;}}_r}{{\mathrm{Ga}}_0}{F}_x---\left(14\right)$

In formula, for initial capacitance when shearing stress is zero, (14) formula is shearing stress input-output characteristic, C _{τ x}with F _xlinear relationship, and its sensitivity

By formula (14) known a ₀less, the sensitivity of tangential 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 tangential 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 Fig. 9 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, $O_{\mathrm{\&tau;}y}=\frac{2{\mathrm{mK\&epsiv;}}_0\&CenterDot;{\mathrm{\&epsiv;}}_r}{a_{0}G}{F}_y;$

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

2.4 main material selection and characterisitic parameter thereof

The pole plate of plane-parallel capacitor is apart from d ₀=0.1mm, upper and lower base plate inner space, except copper foil electrode, is PDMS (dimethyl silicone polymer) the superlastic insulating medium with lost wax process filling.Its machinery and physical characteristics parameter are Young modulus E=6.2MPa, and its shear modulus is G=4.1MPa, relative DIELECTRIC CONSTANT ε during dielectric polorization _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 stress state 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 extension line, consider that each drive electrode is all ground connection in signal level, therefore drive electrode only need share same extension line.Annulus capacitor cell group is connected with sensor-based system signal processor by an extension line 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 sensor-based system signal processor, sensor-based system signal processor 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 an extension line respectively and are connected with sensor-based system signal processor, for calculating the direction of tangential force.Be provided with intermediate translator between described sensor-based system signal processor and capacitor cell, transducer 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 surface can contact with measuring object easily.

The present invention, under the support of new material and new technology, completes the design of a kind of novel three-dimensional power sensitization capacitance combination.At 10 × 10mm ²stress 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 parameter.

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.

Claims (10)

1. a tyre evenness parameter measuring apparatus, it is characterized in that, comprise loading wheel, sensor and sensor-based system signal processor, loading wheel as the engaged wheel curved surface of tire near tire, sensor is located at the two ends up and down of loading wheel as the two ends strong point of loading wheel, sensor gathers radial force between loading wheel and testing tire and side force and sends to sensor-based system signal processor, sensor comprises annulus capacitor cell group and strip capacitor cell group, described strip capacitor cell group is arranged on the corner of the outer substrate of annulus capacitor cell group, 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.

2. tyre evenness parameter measuring apparatus according to claim 1, it is characterized in that, pick-up unit also comprises main shaft and upper and lower wheel rim, the dead in line of upper and lower wheel rim and main shaft, lower wheel rim and integrated spindle axis, upper wheel rim is up and down can free movement, and the axis being parallel of loading wheel axis and main shaft, tire clamping is between upper and lower wheel rim.

3. tyre evenness parameter measuring apparatus 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.

4. tyre evenness parameter measuring apparatus according to claim 3, is characterized in that, 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.

5. tyre evenness parameter measuring apparatus 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 are provided with the skew that initially misplaces in the width direction, and dislocation bias size is identical, direction is contrary.

6. tyre evenness parameter measuring apparatus 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.

7. tyre evenness parameter measuring apparatus according to claim 2, is characterized in that, 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.

8. tyre evenness parameter measuring apparatus 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 modulus of elastic medium, and G is the modulus of rigidity of elastic medium.

9. tyre evenness parameter measuring apparatus according to claim 2, it is characterized in that, described annulus capacitor cell group is connected with sensor-based system signal processor by an extension line 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 sensor-based system signal processor, and described X-direction differential capacitor unit group is connected with sensor-based system signal processor respectively by an extension line with the capacitor cell module induction electrode of Y-direction differential capacitor unit group.

10. tyre evenness parameter measuring apparatus according to claim 2, it is characterized in that, described annulus capacitor cell, be respectively equipped with intermediate translator between capacitor cell module and sensor-based system signal processor, intermediate translator is for arranging voltage to electric capacity or frequency to the transmission coefficient of electric capacity.