CN101975634B - Engine excitation force measurement method employing window length varying phase difference correction method - Google Patents

Abstract

The invention discloses an engine excitation force measurement method employing a window length varying phase difference correction method. In the method, signal frequency error of an engine excitation frequency interval is solved by utilizing phase difference produced by adding Hanning with different time lengths during signal processing after a vibration acceleration signal on the surface or a suspension point of an engine cylinder is discretely sampled, and the signal frequency error is used for solving actual excitation frequency f, amplitude information and phase information of an engine in a vibration displacement frequency spectrum, so that the vibration displacement vector value in an excitation force measurement formula is accurately obtained and combined with other known engine parameters to calculate the excitation force F (f). The method of the invention can solve the problem that due to the lack of accurate phase information during the engine excitation force measurement, a complex non-linear equation needs to be solved.

Description

Use the engine exciting force measuring method that changes the correction method of window appearance potential difference

Technical field

This aspect relates to power machine and signal Processing field, specifically is a kind of frequency, amplitude, phase method for position of accurate identification of Engine vibration signal, is applied to the identification of engine exciting force.

Background technology

The exciting force of engine mainly is to obtain through the rigid dynamics Model Calculation at present, the excitation that main factor is a gas burst power in the cylinder in calculating, rotating inertia force and reciprocal inertia force produced.The major defect of this method is need to obtain precise parameters, and the accurate acquisition of some parameter is a difficulty very, the moment resulting from sidesway that causes like gas burst etc.On the other hand; In actual conditions, engine always links to each other with many annexes, and theoretical calculation formula is not considered the coupling of engine and these annexes usually; This will inevitably cause result of calculation and engineering is actual that certain deviation is arranged, and deviation can be very big in some cases.

In application of practical project, obtain the engine exciting force and studied through the method for experiment by numerous scholars, this is the problem of typically inverting, and normally adopts the frequency response function matrix method of inverting.But in the vibration control problem of engine; What need is the equivalent force and the equivalent moment at Motor Mass Centre place; Owing to can't directly apply excitation at the barycenter place; The reciprocity method is used in the response that also can't directly obtain the barycenter place, therefore can't record transport function, causes the frequency response function matrix method of inverting in the engine exciting force is measured, can't directly use.On the other hand, concerning the exciting force at Motor Mass Centre place was measured, the frequency response function matrix method of inverting was too complicated comparatively speaking.

External scholar J.S.TAO; G.R.LIU and K.Y.LAM etc. has proposed a kind of method (J.S.TAO that measures Motor Mass Centre place exciting force; G.R.LIU and K.Y.LAM is in 2001 articles " Excitation force identification of an engine with velocity data at mounting points " on periodical " Journal of Sound and Vibration ", delivered); The amplitude and the phase information of the three-way vibration velocity spectrum at each the suspension point place of engine that points out to measure through extraction; Can rebuild the exciting force of engine accurately, the exciting force measure equation $F\left(f\right)=[K^{*}-{\left(2\mathrm{\π\; f}\right)}^{2}M]{\left({\stackrel{\‾}{E}}^T\stackrel{\‾}{E}\right)}^{-1}{\stackrel{\‾}{E}}^T\stackrel{\‾}{S}\left(f\right).$ But this method is when extracting phase information; Usually can't obtain absolute phase information; Therefore proposed only to utilize phase differential to obtain the method for exciting force; And this processing introduced and the measurement identical phase variant of counting that suspends, and the non-linear overdetermined equation that makes finding the solution of problem become to find the solution a complicacy has increased the complicacy of finding the solution.

Summary of the invention

The objective of the invention is defective to existing recognition methods; The engine exciting force measuring method that a kind of application changes the correction method of window appearance potential difference is proposed; Solve for want of accurate phase information in the measurement of engine exciting force, and need find the solution the problem of complex nonlinear equation.

The object of the invention realizes through following technical scheme:

A kind of application changes the engine exciting force measuring method of window appearance potential difference correction method, comprises the steps:

(1) coordinate system is set up with correlation parameter and is collected: utilize the engine moment inertia experiment table, test out engine quality m, Motor Mass Centre O; With O is that initial point is set up coordinate system O-XYZ; Y axle forward points to crankshaft free-end, and Z axle forward is confirmed X axle forward by the right-hand rule straight up; Utilize the engine moment inertia experiment table to test out the moment of inertia J of engine again around coordinate system X axle _x, the Y axle moment of inertia J _y, the Z axle moment of inertia J _z, engine is to the product of inertia J of X axle and Y axle _Xy, to the product of inertia J of Y axle and Z axle _Yz, to the product of inertia J of Z axle and X axle _Zx, form the engine quality matrix M;

(2) obtain the multiple stiffness matrix that suspends: engine is passed through mount supports at threst stand; Confirm engine mounting number h, h=3 or h=3; In the coordinate system O-XYZ of engine; Order according to directions X is descending is given the label that suspends; Be defined as first suspend, second suspend ..., h suspends, and with the elastic body test macro the multiple stiffness characteristics that respectively suspends tested, and obtains the first multiple rigidity that suspends

The second multiple rigidity that suspends , the multiple rigidity that suspends of h

Form the multiple stiffness matrix K that suspends ^*=[K ^* ₁K ^* ₂K ^* _h];

(3) sensor installation: on the different test points of engine cylinder surface or suspension point, L three-dimensional acceleration transducer is installed, L>=3, each test point is installed a three-dimensional acceleration transducer; Sensor connects data acquisition unit, and data acquisition unit connects portable computer; In the coordinate system O-XYZ of engine, confirm that according to the descending order of directions X the coordinate of three-dimensional acceleration transducer is respectively [x ₁y ₁z ₁], [x ₂y ₂z ₂] ..., [x _Ly _Lz _L];

(4) on threst stand; Setting engine moves with operate as normal rotating speed w; After treating that operating mode is stable, the acquisition time in 10s～30s, the vibration acceleration signal X of X axle forward, Y axle forward and Z axle forward through data acquisition unit collection and each test point of synchronous recording _1n, X _2nX _LnY _1n, Y _2nY _LnZ _1n, Z _2nZ _LnX wherein _1nBe the vibration acceleration signal sequence with n point of the first test point X axle forward collection, X _LnBe n the vibration acceleration signal sequence of putting that L test point X axle forward is gathered, Y _1nBe n the vibration acceleration signal sequence of putting that the first test point Y axle forward is gathered, Y _LnThe vibration acceleration signal sequence of n the point that L test point Y axle forward is gathered; Z _1nBe n the vibration acceleration signal sequence of putting that the first test point Z axle forward is gathered, Z _LnThe vibration acceleration signal sequence of n the point that L test point Z axle forward is gathered; SF f _s, sampling number N representes the data point number that discrete series comprises, wherein n=0,1 ..., N-1, require f _s=N=2 ^p, P=9 or 10, frequency resolution Δ f=f _s/ N=1;

(5) according to formula $F\left(f\right)=[K^{*}-{\left(2\mathrm{\π\; f}\right)}^{2}M]{\left({\stackrel{\‾}{E}}^T\stackrel{\‾}{E}\right)}^{-1}{\stackrel{\‾}{E}}^T\stackrel{\‾}{S}\left(f\right)$ Measure the engine exciting force, wherein:

Exciting force F (f) be mean engine under humorous excitation frequency f of rotating speed w η, the exciting force F of engine X axle forward _x(f), around the excitation torque M of X axle _x(f), the exciting force F of Y direction _y(f), around the excitation torque M of Y axle _y(f), the exciting force F of Z-direction _z(f), around the excitation torque M of Z axle _z(f);

K ^*＝[K ^* ₁?K ^* ₂···K ^* _h]

$M=\left[\begin{array}{cccccc}m& & & & & \\ & m& & & & \\ & & m& & & \\ & & & J_x& -J_{\mathrm{xy}}& -J_{\mathrm{zx}}\\ & & & -J_{\mathrm{xy}}& J_y& -J_{\mathrm{yz}}\\ & & & -J_{\mathrm{zx}}& -J_{\mathrm{yz}}& J_z\end{array}\right]$

$\stackrel{\‾}{E}=\left[\begin{array}{cccccc}1& 0& 0& 0& z_1& -y_1\\ 0& 1& 0& -z_1& 0& x_1\\ 0& 0& 1& y_1& -x_1& 0\\ 1& 0& 0& 0& z_2& -y_2\\ 0& 1& 0& -z_2& 0& x_2\\ 0& 0& 1& y_2& -x_2& 0\\ \·& \·& \·& \·& \·& \·\\ 1& 0& 0& 0& z_3& -y_3\\ 0& 1& 0& -z_3& 0& x_3\\ 0& 0& 1& y_3& -x_3& 0\end{array}\right]$

$f=\frac{1}{3L}(f_{1x}+f_{1y}+f_{1z}+f_{2x}+f_{2y}+f_{2z}+\·\·\·++f_{\mathrm{Lx}}+f_{\mathrm{Ly}}+f_{\mathrm{Lz}})$

$\stackrel{\‾}{S}\left(f\right)={\left[\begin{array}{cccccccccc}{\mathrm{dX}}_1& {\mathrm{dY}}_1& {\mathrm{dZ}}_1& {\mathrm{dX}}_2& {\mathrm{dY}}_2& {\mathrm{dZ}}_2& \·\·\·& {\mathrm{dX}}_L& {\mathrm{dY}}_L& {\mathrm{dZ}}_L\end{array}\right]}^T$

means that the matrix

the transpose;

Humorous excitation frequency f of η confirms through following method with its corresponding transposed matrix

:

Humorous the η that selects the engine exciting force to analyze, η=0.5,1,1.5,2,2.5 or 3; Behind humorous time of the η of designated analysis engine speed w, carry out following computing:

Vibration acceleration signal sequence X to the first test point X axle forward collection with n point _1n, add Hanning window (Hanning) w (t) 0≤t≤T of time length T=1, carry out N point quick Fourier conversion (FFT) according to formula (1-1), obtain amplitude spectrum X ₁(f); To X _1nAdd time length

Hanning window (Hanning) w (t) 0≤t≤T carries out N/2 point quick Fourier conversion (FFT) according to formula (1-2), obtains amplitude spectrum X ₂(f);

$X_1\left(f\right)=\underset{n=0}{\overset{N-1}{\mathrm{\Σ}}}{x}_n[0.5-0.5\cos \left(\frac{2\mathrm{\πn}}{N}\right)]e^{-j\frac{2\mathrm{\π}}{N}\mathrm{fn}}=R_1\left(f\right)+j{I}_1\left(f\right)=y_1\left(f\right)e^{j{\mathrm{\Φ}}_1\left(f\right)},f=\mathrm{0,1},\·\·\·,\frac{N}{2}-1---(1-1)$

$X_2\left(f\right)=\underset{n=0}{\overset{N/2-1}{\mathrm{\Σ}}}{x}_n[0.5-0.5\cos \left(\frac{4\mathrm{\πn}}{N}\right)]e^{-j\frac{4\mathrm{\π}}{N}\mathrm{fn}}=R_2\left(f\right)+j{I}_2\left(f\right)=y_2\left(f\right)e^{j{\mathrm{\Φ}}_2\left(f\right)},f=\mathrm{0,1,2},\·\·\·,\frac{N}{4}-1---(1-2)$

According to engine speed w, confirm the interval [f of emending frequency ₁, f ₂], wherein Round numbers;

Round numbers;

At the interval [f of emending frequency ₁, f ₂] in, X ₁(f) peak-peak respective frequencies f _i, f _iReal part is R ₁(f _i), imaginary part is I ₁(f _i), phase place is Φ ₁(f _i), amplitude is y ₁(f _i); X ₂(f) peak-peak frequency f _j, phase place is Φ ₂(f _j); If the interval [f of emending frequency ₁, f ₂] interior peak-peak actual frequency is f ₀, f ₀Corresponding true phase place

True amplitude A ₀(f ₀); If f _iFrequency error do

f _iWith actual frequency f ₀Difference

Substitution formula (1-3) is obtained frequency error

$\▿f=-2[{\mathrm{\Φ}}_1\left(f_i\right)-{\mathrm{\Φ}}_2\left(f_j\right)-\frac{\mathrm{\π}(2f_i-f_j)}{2}]/\mathrm{\π}---(1-3)$

Calculate actual frequency f ₀ $f_0=f_i-\▿f---(1-4)$

Calculate the true phase

The spectral function of Hanning window (Hanning) Calculate the amplitude A after the correction according to formula (1-6) ₀(f ₀), form actual frequency f ₀Acceleration with correspondence

$A_0\left(f_0\right)=\frac{y_1\left(f_i\right)}{W(\▿f)}---(1-6)$

To sequence X _2nX _LnY _1n, Y _2nY _LnZ _1n, Z _2nZ _LnWith the vibration acceleration signal sequence X _1nCarry out same processing, obtain the humorous inferior excitation frequency f of engine speed w η respectively _2xF _Lxf _1y, f _2yF _Lyf _1z, f _2zF _Lz

(1≤H≤L), the engine excitation frequency that records its directions X is f for any sensor H in L the sensor test point _Hx, corresponding acceleration does

The engine excitation frequency that records the Y direction is f _Hy, corresponding acceleration does

The engine excitation frequency that records the Z direction is f _Hy, corresponding acceleration does

The directions X displacement of sensor H is dX _H, the displacement of Y direction is dY _H, the displacement of Z direction is dZ _H, obtain the transposed matrix of sensor H thus:

The excitation frequency of L sensor $f=\frac{1}{3L}(f_{1x}+f_{1y}+f_{1z}+f_{2x}+f_{2y}+f_{2z}+\·\·\·++f_{\mathrm{Lx}}+f_{\mathrm{Ly}}+f_{\mathrm{Lz}}),$ And corresponding transposed matrix $\stackrel{\‾}{S}\left(f\right)={\left[\begin{array}{cccccccccc}{\mathrm{DX}}_1& {\mathrm{DY}}_1& {\mathrm{DZ}}_1& {\mathrm{DX}}_2& {\mathrm{DY}}_2& {\mathrm{DZ}}_2& \·\·\·& {\mathrm{DX}}_L& {\mathrm{DY}}_L& {\mathrm{DZ}}_L\end{array}\right]}^T.$

For realizing that further the object of the invention, described crankshaft free-end are the end that bent axle connects belt pulley.

Described engine is defined as suspension point with the contact point that suspends that supports it.

Described operate as normal rotating speed w is preferably 750r/min to 5500r/min; Said operating mode is stable to be meant that the engine speed fluctuation is in 20r/min.

Described engine moment inertia experiment table preferably adopts three string pendulum method of testing experiment tablees.

The present invention only needs the value through conversion η, η=0.5,1,1.5,2,2.5,3 to the exciting force test of different humorous the η of engine; Calculate the interval [f of different frequency refinements ₁, f ₂], recalculate this excitation frequency f and corresponding transposed matrix of humorous time

Solve humorous the exciting force F of η (f) of engine speed w.

With respect to prior art, the present invention has following advantage:

The present invention is through after sampling to the vibration displacement signal discrete on engine cylinder surface or the suspension point; The phase differential that adds the Hanning window (Hanning) of different time length and produce; Utilize precise frequency, amplitude and the phase information of each response point vibration signal of this phase difference correction, thereby improve the measuring accuracy of exciting force.The present invention combines J.S.TAO, the exciting force measure equation that G.R.LIU and K.Y.LAM proposes $F\left(f\right)=[K^{*}-{\left(2\mathrm{\π\; f}\right)}^{2}M]{\left({\stackrel{\‾}{E}}^T\stackrel{\‾}{E}\right)}^{-1}{\stackrel{\‾}{E}}^T\stackrel{\‾}{S}\left(f\right)$ Middle K ^*, M,

Method for solving proposes to use the correction method of change window appearance potential difference and accurately extracts transposed matrix

In frequency, amplitude and phase information, improved and utilized the phase differential method to calculate

Method, avoided finding the solution of problem having been become the non-linear overdetermined equation of finding the solution a complicacy because of utilizing the phase differential method, improved and found the solution

Precision and efficient, and improved the simplicity that F (f) finds the solution.

Embodiment:

Below in conjunction with embodiment the present invention is done further description, need to prove, embodiment does not constitute the qualification that the present invention is required protection domain.

Embodiment 1

(1) utilize three-way pendulum engine rotary inertia experimental bench to test out: certain 1.8L in-line four cylinder engine quality m, Motor Mass Centre O is that initial point is set up coordinate system O-XYZ with barycenter O; And then test out the moment of inertia J of engine around coordinate system X axle _x, the Y axle moment of inertia J _y, the Z axle moment of inertia J _z, engine is to the product of inertia J of X axle and Y axle _Xy, to the inertia J of Y axle and Z axle _Yz, to the inertia J of Z axle and X axle _Zx, form the engine quality matrix M;

$M=\left[\begin{array}{cccccc}m& & & & & \\ & m& & & & \\ & & m& & & \\ & & & J_x& -J_{\mathrm{xy}}& -J_{\mathrm{zx}}\\ & & & -J_{\mathrm{xy}}& J_y& -J_{\mathrm{yz}}\\ & & & -J_{\mathrm{zx}}& -J_{\mathrm{yz}}& J_z\end{array}\right]=\left[\begin{array}{cccccc}80\mathrm{kg}& & & & & \\ & 80\mathrm{kg}& & & & \\ & & 80\mathrm{kg}& & & \\ & & & 7.5\mathrm{kg}{m}^2& 1.5\mathrm{kg}{m}^2& -0.5\mathrm{kg}{m}^2\\ & & & 1.5\mathrm{kg}{m}^2& 3.5\mathrm{kg}{m}^2& 1\mathrm{kg}{m}^2\\ & & & -0.5\mathrm{kg}{m}^2& 1\mathrm{kg}{m}^2& 6\mathrm{kg}{m}^2\end{array}\right]$

(2) confirm engine mounting number h, h=3; In the coordinate system O-XYZ of engine, give the label that suspends according to the descending order of directions X, be defined as and suspend 1, suspend 2 ... The h that suspends adopts German MTS831 type elastic body test system and test to go out the multiple rigidity that respectively suspends, and forms the multiple stiffness matrix that suspends

K ^*＝[K ^* ₁?K ^* ₂?K ^* ₃]＝[(75000+7500j)N/m(70000+7000j)N/m(80000+8000j)N/m]；

(3) be installed in 1.8L in-line four cylinder engine on the German FEV threst stand, adopt CPB three-dimensional acceleration transducer, number L=3 is arranged in the suspension point place.Measure the coordinate of 3 sensor test points through three-coordinates measuring machine, form test point coordinate matrix

$\stackrel{\‾}{E}=\left[\begin{array}{cccccc}1& 0& 0& 0& z_1& -y_1\\ 0& 1& 0& -z_1& 0& x_1\\ 0& 0& 1& y_1& -x_1& 0\\ 1& 0& 0& 0& z_2& -y_2\\ 0& 1& 0& -z_2& 0& x_2\\ 0& 0& 1& y_2& -x_2& 0\\ 1& 0& 0& 0& z_3& -y_3\\ 0& 1& 0& -z_3& 0& x_3\\ 0& 0& 1& y_3& -x_3& 0\end{array}\right]=\left[\begin{array}{cccccc}1& 0& 0& 0& 0.1& -0.3\\ 0& 1& 0& -0.1& 0& 0\\ 0& 0& 1& 0.3& 0& 0\\ 1& 0& 0& 0& -0.2& 0.2\\ 0& 1& 0& 0.2& 0& -0.12\\ 0& 0& 1& -0.2& 0.12& 0\\ 1& 0& 0& 0& -0.2& 0.2\\ 0& 1& 0& 0.2& 0& 0.12\\ 0& 0& 1& -0.2& -0.12& 0\end{array}\right]$

(4) input of CPB three-dimensional acceleration transducer is the data acquisition system (DAS) of German Miller shellfish nurse (BBM) testing apparatus, and data acquisition signal input portable computer is through the PAK test analysis software of installing on the portable computer, real-time monitored and tracer signal;

(5) on threst stand; Set engine with certain operate as normal rotating speed w=1815rpm operation; Treat the stable back of operating mode (being that the fluctuation of speed is in 20r/min), the beginning image data, the data acquisition system (DAS) of German Miller shellfish nurse (BBM) testing apparatus imported signal by CPB three-dimensional acceleration transducer; Through PAK test analysis software, real-time monitored and the tracer signal of installing on the portable computer.Acquisition time length is 30s; SF f _s=512, sampling number N=512, then frequency resolution Δ f=f _s/ N=1, the vibration acceleration signal X of X axle forward, Y axle forward and Z axle forward through data acquisition unit collection and each test point of synchronous recording _1n, X _2n, X _3nY _1n, Y _2n, Y _3nZ _1n, Z _2n, Z _3nWherein n=0,1 ..., N-1; To vibration acceleration signal X _1n, X _2n, X _3nY _1n, Y _2n, Y _3nZ _1n, Z _2n, Z _3nCarry out the conversion of N=512 point fast Fourier.

According to engine speed w=1815rpm, confirm the frequency separation [f that the FT refinement is analyzed ₁, f ₂], the refinement interval of 0.5 humorous excitation frequency f of engine speed w is f ₁=10HZ and f ₂=20HZ; 1 humorous time refinement interval is f ₁=25HZ and f ₂=35HZ; 1.5 humorous time refinement interval is f ₁=40HZ and f ₂=50HZ; 2 humorous times refinement interval is f ₁=55HZ and f ₂=65HZ; 2.5 humorous time refinement interval is f ₁=71HZ and f ₂=81HZ; 3 humorous times refinement interval is f ₁=86HZ and f ₂=96HZ; Each frequency separation [f ₁, f ₂] refinement multiple q=100* (f ₂-f ₁)=1000, step is following:

1) according to frequency resolution amount Δ f after formula (1-6) the calculating refinement ¹

Δf ¹＝0.01 (1-6)

2) confirm the calculated rate preface according to formula (1-7)

{f ₁，f ₁+Δf ¹，f ₁+2Δf ¹，···，f ₁+qΔf ¹＝f ₂} (1-7)

3), only enumerate out 1 humorous time and 2 humorous times the excitation frequency f of engine speed w here, the 1 humorous secondary frequencies interval [f of engine speed w owing to the length relation ₁, f ₂]=[25,35], adopt the FT refinement to analyze, obtain 3 sensor correspondences the excitation frequency f and the acceleration of test point separately

As shown in table 1; Interval [the f of 2 humorous secondary frequencies of engine speed w ₁, f ₂]=[55,65], adopt the FT refinement to analyze, obtain 3 sensor correspondences the excitation frequency f and the acceleration of test point separately

As shown in table 2;

1 humorous secondary frequencies and the acceleration of table 1 engine speed w

2 humorous secondary frequencies and the accelerations of table 2 engine speed w

Obtain thus: when $f=\frac{1}{9}(30.25+30.25+\·\·\·+30.25)=30.25\mathrm{HZ}$ The time,

Transposed matrix $\stackrel{\‾}{S}\left(30.25\right)={\left[\begin{array}{ccccccccc}{\mathrm{DX}}_1& {\mathrm{DY}}_1& {\mathrm{DZ}}_1& {\mathrm{DX}}_2& {\mathrm{DY}}_2& {\mathrm{DZ}}_2& {\mathrm{DX}}_3& {\mathrm{DY}}_3& {\mathrm{DZ}}_3\end{array}\right]}^T,$ Wherein:

$\left[\begin{array}{ccc}{\mathrm{dX}}_1& {\mathrm{dY}}_1& {\mathrm{dZ}}_1\end{array}\right]=\left[\begin{array}{ccc}\frac{-1}{2\mathrm{\π}*30.25}{0.1704e}^{-179.37j}& \frac{-1}{2\mathrm{\π}*30.25}{0.0491e}^{179.42j}& \frac{-1}{2\mathrm{\π}*30.24}{0.4436e}^{0.48j}\end{array}\right]$

$\left[\begin{array}{ccc}{\mathrm{dX}}_2& {\mathrm{dY}}_2& {\mathrm{dZ}}_2\end{array}\right]=\left[\begin{array}{ccc}\frac{-1}{2\mathrm{\π}*30.25}0.0518e^{1.81j}& \frac{-1}{2\mathrm{\π}*30.25}0.1887e^{1.08j}& \frac{-1}{2\mathrm{\π}*30.25}{0.0417e}^{-176.19j}\end{array}\right]$

$\left[\begin{array}{ccc}{\mathrm{dX}}_3& {\mathrm{dY}}_3& {\mathrm{dZ}}_3\end{array}\right]=\left[\begin{array}{ccc}\frac{-1}{2\mathrm{\π}*30.25}{0.0518e}^{1.81j}& \frac{-1}{2\mathrm{\π}*30.25}{0.4715e}^{0.56j}& \frac{-1}{2\mathrm{\π}*30.25}{0.3353e}^{-179.7j}\end{array}\right]$

When $f=\frac{1}{9}(60.5+60.5+\·\·\·+60.5)=60.5\mathrm{HZ}$ The time,

Transposed matrix $\stackrel{\‾}{S}\left(60.5\right)={\left[\begin{array}{ccccccccc}{\mathrm{DX}}_1& {\mathrm{DY}}_1& {\mathrm{DZ}}_1& {\mathrm{DX}}_2& {\mathrm{DY}}_2& {\mathrm{DZ}}_2& {\mathrm{DX}}_3& {\mathrm{DY}}_3& {\mathrm{DZ}}_3\end{array}\right]}^T,$ Wherein:

$\left[\begin{array}{ccc}{\mathrm{dX}}_1& {\mathrm{dY}}_1& {\mathrm{dZ}}_1\end{array}\right]=\left[\begin{array}{ccc}\frac{-1}{2\mathrm{\π}*60.5}{0.2061e}^{0.17j}& \frac{-1}{2\mathrm{\π}*60.5}{0.1592e}^{0.25j}& \frac{-1}{2\mathrm{\π}*60.5}1{.1794e}^{0.06j}\end{array}\right]$

$\left[\begin{array}{ccc}{\mathrm{dX}}_2& {\mathrm{dY}}_2& {\mathrm{dZ}}_2\end{array}\right]=\left[\begin{array}{ccc}\frac{-1}{2\mathrm{\π}*60.5}1.7755e^{-179.79j}& \frac{-1}{2\mathrm{\π}*60.5}0.3839e^{-179.93j}& \frac{-1}{2\mathrm{\π}*60.5}{2.8771e}^{0.12j}\end{array}\right]$

$\left[\begin{array}{ccc}{\mathrm{dX}}_3& {\mathrm{dY}}_3& {\mathrm{dZ}}_3\end{array}\right]=\left[\begin{array}{ccc}\frac{-1}{2\mathrm{\π}*60.5}{1.7755e}^{-179.79j}& \frac{-1}{2\mathrm{\π}*60.5}{0.5075e}^{-0.15j}& \frac{-1}{2\mathrm{\π}*60.5}{0.1938e}^{-179.53j}\end{array}\right]$

(5) fundamental formular of measuring according to the engine exciting force $F\left(f\right)=[K^{*}-{\left(2\mathrm{\π\; f}\right)}^{2}M]{\left({\stackrel{\‾}{E}}^T\stackrel{\‾}{E}\right)}^{-1}{\stackrel{\‾}{E}}^T\stackrel{\‾}{S}\left(f\right),$ Wherein:

Mass matrix M in the substitution (1), the multiple stiffness matrix K that suspends in (2) ^*, the measuring point coordinates matrix in (3)

When asking 1 humorous exciting force of engine speed w, substitution f=30.25HZ with $\stackrel{\‾}{S}\left(30.25\right)={\left[\begin{array}{ccccccccc}{\mathrm{DX}}_1& {\mathrm{DY}}_1& {\mathrm{DZ}}_1& {\mathrm{DX}}_2& {\mathrm{DY}}_2& {\mathrm{DZ}}_2& {\mathrm{DX}}_3& {\mathrm{DY}}_3& {\mathrm{DZ}}_3\end{array}\right]}^T,$ 1 humorous exciting force obtaining engine start machine rotating speed w is as shown in table 3; When asking 2 humorous exciting forces of engine speed w, substitution f=60.5HZ with $\stackrel{\‾}{S}\left(60.5\right)={\left[\begin{array}{ccccccccc}{\mathrm{DX}}_1& {\mathrm{DY}}_1& {\mathrm{DZ}}_1& {\mathrm{DX}}_2& {\mathrm{DY}}_2& {\mathrm{DZ}}_2& {\mathrm{DX}}_3& {\mathrm{DY}}_3& {\mathrm{DZ}}_3\end{array}\right]}^T,$ 2 humorous exciting forces obtaining engine start machine rotating speed w are as shown in table 4;

1 humorous exciting force of table 3 engine speed w

2 humorous exciting forces of table 4 engine speed w

Embodiment 1 has explained that the present invention is through after sampling to the vibration displacement signal discrete on engine cylinder surface or the suspension point; The phase differential that adds the Hanning window (Hanning) of different time length and produce; Utilize precise frequency, amplitude and the phase information of each response point vibration signal of this phase difference correction, thereby improve the measuring accuracy of exciting force.

Claims (5)

1. use the engine exciting force measuring method that changes the correction method of window appearance potential difference, it is characterized in that comprising the steps:

(1) coordinate system is set up with correlation parameter and is collected: utilize the engine moment inertia experiment table, test out engine quality m, Motor Mass Centre O; With O is that initial point is set up coordinate system O-XYZ; Y axle forward points to crankshaft free-end, and Z axle forward is confirmed X axle forward by the right-hand rule straight up; Utilize the engine moment inertia experiment table to test out the moment of inertia J of engine again around coordinate system X axle _x, the Y axle moment of inertia J _y, the Z axle moment of inertia J _z, engine is to the product of inertia J of X axle and Y axle _Xy, to the product of inertia J of Y axle and Z axle _Yz, to the product of inertia J of Z axle and X axle _Zx, form the engine quality matrix M;

(2) obtain the multiple stiffness matrix that suspends: engine is passed through mount supports at threst stand; Confirm engine mounting number h, h=3; In the coordinate system O-XYZ of engine, give the label that suspends according to the descending order of directions X, be defined as first suspend, second suspend ... H suspends, and the multiple stiffness characteristics that respectively suspends is tested the multiple rigidity that acquisition first suspends with the elastic body test macro

The second multiple rigidity that suspends

The multiple rigidity that h suspends Form the multiple stiffness matrix K that suspends ^*=[K ^* ₁K ^* ₂K ^* _h];

(3) sensor installation: on the different test points of engine cylinder surface or suspension point, L three-dimensional acceleration transducer is installed, L>=3, each test point is installed a three-dimensional acceleration transducer; Sensor connects data acquisition unit, and data acquisition unit connects portable computer; In the coordinate system O-XYZ of engine, confirm that according to the descending order of directions X the coordinate of three-dimensional acceleration transducer is respectively [x ₁y ₁z ₁], [x ₂y ₂z ₂] ... [x _Ly _Lz _L];

(4) on threst stand; Setting engine moves with operate as normal rotating speed w; After treating that operating mode is stable, the acquisition time in 10s～30s, the vibration acceleration signal X of X axle forward, Y axle forward and Z axle forward through data acquisition unit collection and each test point of synchronous recording _1n, X _2nX _LnY _1n, Y _2nY _LnZ _1n, Z _2nZ _LnX wherein _1nBe the vibration acceleration signal sequence with n point of the first test point X axle forward collection, X _LnBe n the vibration acceleration signal sequence of putting that L test point X axle forward is gathered, Y _1nBe n the vibration acceleration signal sequence of putting that the first test point Y axle forward is gathered, Y _LnThe vibration acceleration signal sequence of n the point that L test point Y axle forward is gathered; Z _1nBe n the vibration acceleration signal sequence of putting that the first test point Z axle forward is gathered, Z _LnThe vibration acceleration signal sequence of n the point that L test point Z axle forward is gathered; SF f _s, sampling number N representes the data point number that discrete series comprises, wherein n=0,1 ..., N-1, require f _s=N=2 ^p, P=9 or 10, frequency resolution Δ f=f _s/ N=1;

(5) according to formula $F\left(f\right)=[K^{*}-{\left(2\mathrm{\π\; f}\right)}^{2}M]{\left({\stackrel{\‾}{E}}^T\stackrel{\‾}{E}\right)}^{-1}{\stackrel{\‾}{E}}^T\stackrel{\‾}{S}\left(f\right)$ Measure the engine exciting force, wherein: Exciting force F (f) be mean engine under humorous excitation frequency f of rotating speed w η, the exciting force F of engine X axle forward _x(f), around the excitation torque M of X axle _x(f), the exciting force F of Y direction _y(f), around the excitation torque M of Y axle _y(f), the exciting force F of Z-direction _z(f), around the excitation torque M of Z axle _z(f);

K ^*＝[K ^* ₁?K ^* ₂···K ^* _h]

$M=\left[\begin{array}{cccccc}m& & & & & \\ & m& & & & \\ & & m& & & \\ & & & J_x& -J_{\mathrm{xy}}& -J_{\mathrm{zx}}\\ & & & -J_{\mathrm{xy}}& J_y& -J_{\mathrm{yz}}\\ & & & -J_{\mathrm{zx}}& -J_{\mathrm{yz}}& J_z\end{array}\right]$

$\stackrel{\‾}{E}=\left[\begin{array}{cccccc}1& 0& 0& 0& z_1& -y_1\\ 0& 1& 0& -z_1& 0& x_1\\ 0& 0& 1& y_1& -x_1& 0\\ 1& 0& 0& 0& z_2& -y_2\\ 0& 1& 0& -z_2& 0& x_2\\ 0& 0& 1& y_2& -x_2& 0\\ \·& \·& \·& \·& \·& \·\\ 1& 0& 0& 0& z_3& -y_3\\ 0& 1& 0& -z_3& 0& x_3\\ 0& 0& 1& y_3& -x_3& 0\end{array}\right]$

$f=\frac{1}{3L}(f_{1x}+f_{1y}+f_{1z}+f_{2x}+f_{2y}+f_{2z}+\·\·\·++f_{\mathrm{Lx}}+f_{\mathrm{Ly}}+f_{\mathrm{Lz}})$

$\stackrel{\‾}{S}\left(f\right)={\left[\begin{array}{cccccccccc}{\mathrm{dX}}_1& {\mathrm{dY}}_1& {\mathrm{dZ}}_1& {\mathrm{dX}}_2& {\mathrm{dY}}_2& {\mathrm{dZ}}_2& \·\·\·& {\mathrm{dX}}_L& {\mathrm{dY}}_L& {\mathrm{dZ}}_L\end{array}\right]}^T$

indicates matrix transposed;

Humorous excitation frequency f of η confirms through following method with its corresponding transposed matrix

:

Humorous the η that selects the engine exciting force to analyze, η=0.5,1,1.5,2,2.5 or 3; Behind humorous time of the η of designated analysis engine speed w, carry out following computing:

Vibration acceleration signal sequence X to the first test point X axle forward collection with n point _1n, add Hanning window w (t) 0≤t≤T of time length T=1, carry out the conversion of N point quick Fourier according to formula (1-1), obtain amplitude spectrum X ₁(f); To X _1nAdd time length Hanning window w (t) 0≤t≤T carries out N/2 point quick Fourier conversion (FFT) according to formula (1-2), obtains amplitude spectrum X ₂(f);

$X_1\left(f\right)=\underset{n=0}{\overset{N-1}{\mathrm{\Σ}}}{x}_n[0.5-0.5\cos \left(\frac{2\mathrm{\πn}}{N}\right)]e^{-j\frac{2\mathrm{\π}}{N}\mathrm{fn}}=R_1\left(f\right)+j{I}_1\left(f\right)=y_1\left(f\right)e^{j{\mathrm{\Φ}}_1\left(f\right)},f=\mathrm{0,1},\·\·\·,\frac{N}{2}-1---(1-1)$

$X_2\left(f\right)=\underset{n=0}{\overset{N/2-1}{\mathrm{\Σ}}}{x}_n[0.5-0.5\cos \left(\frac{4\mathrm{\πn}}{N}\right)]e^{-j\frac{4\mathrm{\π}}{N}\mathrm{fn}}=R_2\left(f\right)+j{I}_2\left(f\right)=y_2\left(f\right)e^{j{\mathrm{\Φ}}_2\left(f\right)},f=\mathrm{0,1,2},\·\·\·,\frac{N}{4}-1---(1-2)$

According to engine speed w, confirm the interval [f of emending frequency ₁, f ₂], wherein

Round numbers;

Round numbers;

At the interval [f of emending frequency ₁, f ₂] in, X ₁(f) peak-peak respective frequencies f _i, f _iReal part is R ₁(f _i), imaginary part is I ₁(f _i), phase place is Φ ₁(f _i), amplitude is y ₁(f _i); X ₂(f) peak-peak frequency f _j, phase place is Φ ₂(f _j); If the interval [f of emending frequency ₁, f ₂] interior peak-peak actual frequency is f ₀, f ₀Corresponding true phase place

True amplitude A ₀(f ₀); If f _iFrequency error do

f _iWith actual frequency f ₀Difference

Substitution formula (1-3) is obtained frequency error

$\▿f=-2[{\mathrm{\Φ}}_1\left(f_i\right)-{\mathrm{\Φ}}_2\left(f_j\right)-\frac{\mathrm{\π}(2f_i-f_j)}{2}]/\mathrm{\π}---(1-3)$

Calculate actual frequency f ₀ $f_0=f_i-\▿f---(1-4)$

Calculate the true phase

The spectral function of Hanning window

Calculate the amplitude A after the correction according to formula (1-6) ₀(f ₀), form actual frequency f ₀Acceleration with correspondence

$A_0\left(f_0\right)=\frac{y_1\left(f_i\right)}{W(\▿f)}---(1-6)$

To sequence X _2nX _LnY _1n, Y _2nY _LnZ _1n, Z _2nZ _LnWith the vibration acceleration signal sequence X _1nCarry out same processing, obtain the humorous inferior excitation frequency f of engine speed w η respectively _2xF _Lxf _1y, f _2yF _Lyf _1z, f _2zF _Lz

(1≤H≤L), the engine excitation frequency that records its directions X is f for any sensor H in L the sensor test point _Hx, corresponding acceleration does

The engine excitation frequency that records the Y direction is f _Hy, corresponding acceleration does

The engine excitation frequency that records the Z direction is f _Hz, corresponding acceleration does

The directions X displacement of sensor H is dX _H, the displacement of Y direction is dY _H, the displacement of Z direction is dZ _H, obtain the transposed matrix of sensor H thus:

The excitation frequency of L sensor $f=\frac{1}{3L}(f_{1x}+f_{1y}+f_{1z}+f_{2x}+f_{2y}+f_{2z}+\·\·\·++f_{\mathrm{Lx}}+f_{\mathrm{Ly}}+f_{\mathrm{Lz}}),$ And corresponding transposed matrix $\stackrel{\‾}{S}\left(f\right)={\left[\begin{array}{cccccccccc}{\mathrm{DX}}_1& {\mathrm{DY}}_1& {\mathrm{DZ}}_1& {\mathrm{DX}}_2& {\mathrm{DY}}_2& {\mathrm{DZ}}_2& \·\·\·& {\mathrm{DX}}_L& {\mathrm{DY}}_L& {\mathrm{DZ}}_L\end{array}\right]}^T.$

2. application according to claim 1 changes the engine exciting force measuring method of window appearance potential difference correction method, it is characterized in that: described crankshaft free-end is the end that bent axle connects belt pulley.

3. application according to claim 1 changes the engine exciting force measuring method of window appearance potential difference correction method, it is characterized in that: described engine is defined as suspension point with the contact point that suspends that supports it.

4. application according to claim 1 changes the engine exciting force measuring method of window appearance potential difference correction method, and it is characterized in that: described operate as normal rotating speed w is 750r/min to 5500r/min; Said operating mode is stable to be meant that the engine speed fluctuation is in 20r/min.

5. application according to claim 1 changes the engine exciting force measuring method of window appearance potential difference correction method, and it is characterized in that: described engine moment inertia experiment table adopts three string pendulum method of testing experiment tablees.