耦合映象中的尖峰与扭结结构

Pattern with kinks and pulses in coupled periodic map lattices

Weiqing Liu,1,2,3,4Ye Wu,1,2,3Wei Zou,1,2Jinghua Xiao,3and Meng Zhan1,*

1Wuhan Institute of Physics and Mathematics,Chinese Academy of Sciences,Wuhan430071,China

2Graduate School of the Chinese Academy of Sciences,Beijing100049,China

3School of Science,Beijing University of Posts and Telecommunications,Beijing100876,China

4School of Science,Jiangxi University of Science and Technology,Ganzhou341000,China ?Received2February2007;revised manuscript received10May2007;published27September2007?

In this paper,we reinvestigate the period doubling of kink-antikink patterns in coupled periodic logistic map

lattices.In contrast to earlier observations,we?nd an additional mode structure,a pulse.An unusual brushlike

bifurcation diagram and an oscillation of the largest Lyapunov exponent versus the coupling are observed.We

propose a mode analysis method to analyze the cases of different mode numbers for these two basic modes

?kink and pulse?.We believe that our investigations can shed improved light on the dynamics of coupled

periodic map lattices.

DOI:10.1103/PhysRevE.76.036215PACS number?s?:05.45.Ra,05.45.Pq

I.INTRODUCTION

Most of the earlier studies?1?on nonlinear dynamics have

concentrated on the temporal behavior of low-dimensional

systems.However,a variety of physical systems of interest

have many spatial degrees of freedom.Therefore,recent

studies of spatiotemporal systems?2–12?have been central

in nonlinear science and have received wide attention.One

such system is the model of coupled map lattices?CMLs?

?3–12?,which serves as a paradigm for spatially extended

nonlinear systems due to both its rich phenomenology and its

computational ef?ciency.

In this paper,we investigate the standard one-dimensional

diffusively coupled map lattice,written as

x n+1?i?=?1???f…x n?i?…+?

2

?f…x n?i?1?…+f…x n?i+1?…?,

i=1,...,L,?1?where n is the discrete time step,i denotes the lattice site, and?indicates the coupling intensity.Periodic boundary conditions are chosen throughout this paper.Without loss of generality,we take the logistic map for each lattice as f?x?

=?x?1?x??13,14?.The dynamics of the single logistic map is well known.By increasing the nonlinear coef?cient?,the dynamics undergoes a period-doubling cascade and transits to chaos at the Feigenbaum accumulation point?????=3.5699456...?.The?rst several period-doubling param-

eters are?1→2=3?for the P1to P2transition?and?2→4 =1+?6=3.44941...?for the P2to P4transition?.Beyond ??,multiband chaos appears and an inverse period-doubling cascade for the chaotic bands takes place,and at?r?3.678, two chaotic bands merge into a single-band chaotic state.

For coupled logistic map lattices?3–12?,much richer phe-nomena have been found due to the mutual interactions of the local nonlinearity???and the spatial coupling???,and several distinct patterns have been classi?ed so far?3–7?,

including frozen random patterns,pattern selection,defect

turbulence,pattern competition intermittency,fully devel-

oped turbulence,and so on.Below the value?r a frozen random pattern?5,8,10?appears,which is characterized by a

system well separated by kink and antikinks?walls?into sev-

eral isolated domains,in which the motions may be periodic

or chaotic.As?is decreased further,within the periodic parameter regime??1→2??????,the pattern gets simpler, characterized by?at regions and domain boundaries?kinks

or antikinks?.This has been termed period doubling of kink-

antikink patterns?8?.Nevertheless,before the?rst period-

doubling bifurcation point?1→2,there is only one trivial homogeneous period-1pattern available.In this regard,the pattern with kinks is the simplest but nontrivial complex pat-tern in coupled map lattices.Some important qualitative fea-tures have been addressed so far?8?:?1?The pattern is?xed in time;?2?if we start from a random initial condition,the pattern of the attractor is random in space and depends on the initial conditions;?3?the width of a kink is rather small and it increases as the coupling is increased.Obviously,a peri-odic pattern with kinks shares some essential properties with the frozen random pattern,which can be chaotic locally in some lattices,and may belong to the frozen random state, although it has also been viewed as an independent type of pattern with periodic behavior by some other researchers ?11?.

In the present work,we reinvestigate the period doubling

of the kink-antikink pattern?8?.Our results show that,even

for this simple pattern,previous observations are incomplete.

A different type of mode,a pulse,is found.Both kink and

pulse play constructive roles in the system’s dynamical be-

havior.Furthermore,we develop a mode analysis method to

characterize and even predict the pattern in a quantitative

way.

II.NUMERICAL OBSERV ATIONS

Let us consider?=3.1for a period-2logistic map.In the absence of coupling??=0?,all lattices will converge to the stable period-2states x1?and x2?,and alternate between them

*Author to whom correspondence should be addressed.

zhanmeng@https://www.wendangku.net/doc/c1160274.html,

PHYSICAL REVIEW E76,036215?2007?

in time.x 1?=?1+?????+1????3??/2?and x 2?=?1+?

+???+1????3??/2?,which can be easily calculated.x ?=1?1/?is the ?xed point of the single logistic map and is

unstable after ?1→2=3.x 1??0.55801,x 2??0.76457,and x ?

?0.67742for ?=3.1considered here.Figure 1shows snap-shots for different coupling strengths for the ?rst 200lattices only.?=0.03,0.085,0.14,and 0.20for Figs.1?a ?–1?d ?,re-spectively.x =x ?is indicated by the dashed horizontal lines in the ?gures.The whole system size L is 1000and all results are unchanged for any suf?ciently large L .In Fig.1,the parameter ?is adiabatically increased,by using the ?nal con-?guration as the initial state for the subsequent simulation with ?increasing in steps of ??=0.001.Clearly the coupled system is well self-organized to a frozen random state with

some ?at regions ?the original period-2positions x 1?and x 2?

?divided by domain boundaries ?kinks ?.Here the word frozen means that all lattices switch to other positions in one time step and are unchanged at every second time step.The ran-domness of this pattern has also been well observed;we get different stable patterns for different initial conditions but the global structure and the detailed mode structures remain un-changed,as we will see.Both the ?at regions and the bound-aries ?encircled by the thin rectangular boxes ?get wider with the increase of ?;this ?nding is consistent with previous observations.

If we take a closer look at these patterns,surprisingly some unusual pulse structures,which are indicated by the heavy rectangular boxes,can be found.Clearly,the pulses,which stand on the same side of the peaks,are distinct from the kinks ?or antikinks ?,which connect the two different sides.However,like the kinks,the pulses also get wider with increase of the coupling ?compare Figs.1?a ?–1?d ??,i.e.,more lattices get into the disordered regions.In this paper,we refer to the particular localized coherent structure ?kink or pulse ?in space as an independent mode.Note that these two differ-ent mode patterns considered as two basic coherent struc-

tures,as illustrated in Fig.2?a ?for the kink ?front ?and Fig.2?b ?for the pulse,have been extensively studied in the pat-tern formation ?eld ?2?.

Furthermore,to show the variation of the patterns versus ?clearly,we plot the bifurcation diagram in Fig.3?a ?and characterize the patterns with the maximum Lyapunov expo-nent ?max in Fig.3?b ?.The Lyapunov characteristic exponent ?1?gives the rate of exponential divergence from perturbed initial conditions.The maximum Lyapunov exponent,the largest one in the Lyapunov characteristic exponent spec-trum,is the most important one for characterizing the sys-tem’s https://www.wendangku.net/doc/c1160274.html,ually,if it is larger than zero,the system is chaotic,whereas if it is equal to or lower than zero,the system is regular.A standard numerical computational method for ?max ?15?with the linearization equations of Eq.?1?has been utilized.Unusual global patterns with a brush-0

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FIG.1.Snapshots of the sites 1?200of the CML ?L =1000?un-der different couplings.Patterns emphasized in the thin rectangular boxes are kink patterns of different modes M k and those in the heavy rectangular boxes are pulse pat-terns of different modes M p .?a ??=0.03,?M k ,M p ?=?2,2?.?b ??=0.085,?M k ,M p ?=?4,3?.?c ??=0.14,

?M k ,M p ?=?6,6?.?d ??=0.20,?M k ,M p ?=?6,7?.

FIG.2.?a ?,?b ?Schematic illustrations for the kink ?front ?and the pulse,respectively.?c ??d ??e ?.Schematic diagrams of the modes for the kink pattern M k =2,and the pulse patterns M p =2and 3,respectively.The unknown sites are denoted by open circles,while the ?xed boundaries are denoted by stars.

LIU et al.

PHYSICAL REVIEW E 76,036215?2007?

like bifurcation structure and a zigzag Lyapunov exponent form are discernible.Roughly,the disordered brushlike curves ?branches ?originate and bifurcate from the several main unbroken curves ?stems ?,and break at certain cou-plings,whose values correspond to the zero-crossing transi-tion points of ?max .We should note that the roughly equal distance between these critical coupling parameters is a co-incidence for this particular parameter ?=3.1only.All these observations are regarded as signi?cant and need a theoreti-cal explanation.

III.THE MODE ANALYSIS

Let us consider the patterns in Fig.1and focus our atten-tion on the detailed mode structure of the isolated kinks and pulses.As both the kinks and the pulses are well separated by the ?at regions,we might be able to cut them from the whole system.We schematically show the isolated mode structures for the mode of the kink ?M k =2?in Fig.2?c ?.Due to the symmetry,only even modes for the kink are possible.Here the mode number M k corresponds to the number of lattices moving into the middle region of the kink mode.For example,for M k =2,shown in Fig.2?c ?,there are only two lattices ?indicated with the open circles ?,whose positions are

within x 1?and x 2?

,surrounded by the two boundary lattices ?xed to x 1?and x 2??denoted by the stars ?.This mode could approximately describe the kink structure that is highlighted by the thin box in Fig.1?a ?.Similarly,we schematically show the even mode of the pulse ?M p =2?and the odd mode of the pulse ?M p =3?in Figs.2?c ?and 2?d ?,respectively.Here M p represents the number of lattices above x ?in the mode distribution.The single mode of the pulse having three lattices ?points ?above x ?in M p =3,illustrated in Fig.2?e ?,is a good approximation to the structure emphasized with the heavy box in Fig.1?b ?.Thus,with the above notation,?M k =2,M p =2?,?M k =4,M p =3?,?M k =6,M p =6?,and ?M k =6,M p =7?could represent the isolated modes for the kinks and the pulses in Figs.1?a ?–1?d ?,respectively.

One may ask,can we predict these modes,or,in particu-lar,obtain the speci?c locations of these lattices?The answer

is yes.One reason is that now in the mode approximation the

two boundaries of the kink are ?xed at x 1?and x 2?

,the two boundaries of the pulse are ?xed to x 1?,and both the kinks and pulses have been well cut out from the whole coupled system.The other reason is that the unknowns ?the positions of the lattices within the mode ?will asymptote to the stable solutions in the isolated mode equations for proper initial settings for these unknowns.From the original coupling equations ?Eq.?1??the coupled equations for the M k mode read

x n +1?1?=f …x n ?1?…,

x n +1?i ?=?1???f …x n ?i ?…+?

2

?f …x n ?i ?1?…+f …x n ?i +1?…?,

i =2,...,N ?1,x n +1?N ?=f …x n ?N ?…,

?2?

with the two boundary lattices ?xed to x 0?1?=x 1?and x 0?N ?=x 2?

for the kink mode.N =M k +2and M k is even.The nu-merical results of the bifurcation diagrams for M k =2,4,and 6are presented in Figs.4?a ?–4?c ?,respectively,where we can see how the mode structure changes with the coupling strength.For convenience,in solving the equations we con-sider the symmetry of the mode.The different branches in each panel indicate the solution branches for the different lattices of the corresponding mode.Clearly,the number of branches in Fig.4becomes larger for larger M k ;there are M k +2branches for the M k kink mode.Two trivial branches

for x 1?and x 2?

?the top and the bottom horizontal lines ?are always solutions of the equations.We also ?nd that for the M k =6mode the number of branches splits from 2to 4at ??0.05,and from 4to 6at ??0.12.This ?nding is consistent with our previous observation that the width of the kink gets larger with increase in the coupling and more lattices move into the middle kink regions.For small coupling,the higher modes degenerate into the low modes ?compare the curves

in

FIG.3.?a ?Bifurcation diagram of the coupled map lattice and ?b ?the maximum Lyapunov exponent of the CML ?max vs ?

.

FIG.4.?a ?,?b ?,?c ?Bifurcation diagrams of the kink from the mode analysis for the different mode numbers M k =2,4,and 6,respectively.

PATTERNS WITH KINKS AND PULSES IN COUPLED …PHYSICAL REVIEW E 76,036215?2007?

Fig.4?.Thus we need to consider only the M k =6mode in the parameter regime 0???0.2studied here.

Similarly,we solve the mode equations for the pulse with the same form as Eqs.?2?but with the two boundary lattices

?xed to x 0?1?=x 1?and x 0?N ?=x 1?

and N being suf?ciently large ?N ?M p ?.In simulations,a special initial condition for the M p mode should be used:the initial values for the middle M p lattices have to be set larger than x ?and the others lower than x ?.In solving the equations we consider the symmetry of the mode again.We plot the bifurcation diagrams for each mode of the pulse from M p =1to 7in Fig.5.Clearly,the number of branches also gets larger for larger M p as more lattices move into the middle pulse regions;in particular,there are ?M p +1?/2branches above x ?for the odd M p ?or M p /2branches for the even M p ?owing to symmetry ?see Figs.2?d ?and 2?e ?for the schematic de?nition of the pulse mode ?.Unlike the splitting behavior of the bifurcation curves of the modes of the kink,the bifurcation curves of the modes of the pulse become broken step by step from low to high mode number.The transition parameters for the modes from 1to 7are ??0.029,0.059,0.092,0.120,0.151,0.178,and 0.204,respectively.The mechanism for this instability will be investigated below.

We plot all the bifurcation diagrams of M k =6?Fig.4?c ??and M p from 1to 7?Fig.5?in Fig.6?a ?.All of the other branches at the next time step have been added.Clearly,the pattern is similar to the original bifurcation diagram for all lattices ?Fig.3?a ??.We also calculate the maximum

Lyapunov exponent for each mode with the same standard numerical method ?15?but this time with the reference orbit of the mode equations ?Eqs.?2??.The results are shown in Fig.6?b ?.The largest values at ?xed ?for each mode are chosen and plotted in Fig.6?c ?,which is largely similar to the ?max of the coupled systems in Fig.3?b ?.We would like to emphasize that our mode analysis theory is only an ap-proximation theory,which in principle allows us to cut iso-lated spatial structures ?kinks or pulses ?surrounded by ?at regions from the whole coupled system for an independent analysis.Thus,although the main theoretical results are at-tractive,the predicted values for the thresholds of ?max ap-pear a little earlier than the real values ?comparing Fig.6?c ?with Fig.3?b ??.

Our mode analysis method not only catches the global feature of the patterns,as shown in the bifurcation ?gure and the maximum Lyapunov exponent plot in Fig.5,but also predicts the detailed structure for the lattices,given the spa-tial position and the mode number of the speci?c mode.For instance,the modes in the boxes in Fig.1have been well predicted,as exempli?ed in Fig.7?comparing the left and right columns ?.

One ?nal question still needs to be answered:What is the underlying mechanism for the instability of the pulse mode,or what kind of bifurcation is supposed to happen when the maximum Lyapunov exponent reaches zero?From the bifur-cation diagrams of the pulse modes,we know that the high lattices get lower and the low lattices get higher with in-crease of the coupling,and then the pulse mode becomes unstable and disappears completely as the critical coupling parameter is touched ?see,for example,Fig.5?a ??.Thus,a tangent bifurcation is expected.To check this point,a nu-merical experiment is performed by using the

Newton-

FIG.5.?a ?–?g ?The same as Fig.4for the pulse number M p from 1to

7.

FIG.6.?Color online ??a ?Bifurcation diagram of the model for the kink and pulse patterns for all modes M k =6and M p ?from 1to 7?.?b ?Maximum Lyapunov exponents ?MLEs ?of the pulses for each mode M p ?from 1to 6?and the kink M k =6vs ?.?c ?The largest value of the MLEs for all the kink and pulse modes obtained in ?b ?vs ?.

LIU et al.PHYSICAL REVIEW E 76,036215?2007?

Raphson algorithm ?16?to ?nd the solutions of the pulse mode equations ?Eqs.?2??.Unlike the usual brute-force ap-proach,which can get a stable solution only and has been used in Figs.4and 5,the Newton-Raphson approach can locate stable and unstable limit sets.The results are shown in Figs.8?a ?and 8?b ?for M p =1and 2,respectively.The stable solutions,which are the same as those in the bifurcation diagrams in Fig.5,are denoted by the solid points,and the newly found unstable solutions are denoted by the open ones.Remarkably,the stable branches of the pulse collide with the unstable branches at the critical parameter,and the whole stable pulse mode is annihilated.Therefore,the de-structive nature of the pulse mode through the tangent bifur-cation has been veri?ed.The unstable solution obtained has a structure that is quite different from that of the corresponding stable solution.One clear observation is that the stable pulse

solution starts from the x 1??or x 2?

?point at ?=0,whereas one of the middle unstable pulse solution curves starts from the x ?point.It is notable that,apart from the unstable branches plotted in Fig.8,several other unstable solutions have been obtained from the simulations for different initial condition settings,which are not included in the ?gure and have no signi?cant contribution to the instability of the mode.Thus,now it is easy to understand the unusual brushlike bifurcation diagram and the zigzag Lyapunov exponent pattern in Fig.3,and the signi?cant but distinct roles of the kink and pulse modes in the organization of the patterns:the effect of the kink is modest,but that of the pulse is severe.

We can easily extend the above analysis of the period-2case to higher-period cases.For example,Fig.9?a ?shows a period-4pattern at one time instant at ?=3.5and ?=0.3.Clearly,both kinks and pulses of different modes,high-lighted with the boxes,are visible,although this time the situation becomes more complicated with four possible sub-branches ?boundaries ?in which the kinks and the pulses can be chosen.Figure 9?b ?displays the bifurcation diagram of the coupled systems ?Eq.?1??,and for comparison Fig.9?c ?plots our theoretical prediction result after we carefully ana-lyzed all the possible modes by the mode analysis method.Again they are in good agreement.

IV .CONCLUSION AND BRIEF DISCUSSION

In conclusion,we have studied the period doubling of kink-antikink patterns in coupled map lattices.This type of pattern is simple but complex;it takes place immediately after the period-doubling bifurcation of the map.On the ba-sis of the mode analysis,the common features of the patterns constructed by the three distinct modes,including the kink,the pulse,and the ?at,have been well uncovered.The self-organization,the evolution process,and the bifurcation be-havior have been revealed.To conclude,the dynamics of the complex patterns in periodic regimes with both kinks and

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FIG.7.Left column:?a ?,?b ?,?c ?Enlargements of the thin box in Fig.1?d ?,the heavy box in Fig.1?a ?,and the heavy box in Fig.1?b ?,respectively.Right column:?d ?,?e ?,?f ?Theoretical predictions of the modes M k =6,M p =2,and M p =3,

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FIG.8.?Color online ??a ?,?b ?The same as Fig.5for the pulse numbers M p =1and 2,respectively,with the Newton-Raphson al-gorithm used instead.The solid ?open ?dots represent the stable ?unstable ?solutions.Clearly,the stable and unstable solution branches collide and both are annihilated at the instability coupling parameter,re?ecting the tangent bifurcation nature.The inset in ?b ?is the enlargement of the left lower part of the two stable and unstable branches.

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PHYSICAL REVIEW E 76,036215?2007?

pulses has been well described with the help of our mode analysis.

Finally,it is worthwhile to give some brief discussion.First,except for the kink and pulse solutions discussed in the paper,there exist some stable solutions to the mode equa-tions ?Eqs.?2??which have not been considered.For in-stance,there exist similar kink solutions with odd numbers of oscillators with the middle point being on the ?xed P 1solution under suf?ciently large coupling.Nevertheless,in coupled systems,a small perturbation might shift the above-mentioned odd-number kink mode to the more stable even-number kink mode,which actually makes the odd-number

kinks unobservable;this point has been con?rmed by the observation of the pattern distributions in Fig.1.Second,we have also tested the cases where the coupled logistic maps are nonidentical with small amounts of random parameter mismatch ?e.g.,the ?i ’s have been varied within ?????,?+???,?=3.1and ??=0.005?,and the global pat-terns with kinks and pulses persist.Thus,the observations with respect to the isolated mode structure appear to be ro-bust for small parameter disturbances.Third,we admit that the mode analysis method has been developed in different circumstances for completely different problems,such as the analysis of a periodic window in weakly coupled map lat-tices ?9?and the study of generalized splay states induced by weak mutual resonant interactions in coupled chaotic ?ow systems ?17,18?.In these two cases,only a single mode with three coupled nonlinear elements at extremely weak coupling has been discussed.Fourth,we would like to emphasize that,although our study appears to be a simple model study,it has the potential to impact numerous other systems.In particular,the analytical method could be bene?cial.For example,in two-dimensional complex oscillatory chemical systems de-scribed by a partial differential equation,the global period-2spiral waves with a locally period-1defect line ?19,20?have some qualitative features quite similar to the kink-pulse pat-tern studied here.The studies not only will attract general interest from researchers in the ?elds of spatiotemporal chaos and pattern dynamics,but also have many potential applica-tions in the ?elds of biology,ecology,chemistry,mathemat-ics,and engineering.

ACKNOWLEDGMENTS

This work was partially supported by the Foundation of Wu-han Institute of Physics and Mathematics under Grant No.T06S607,and the National Natural Science Foundation of China under Grants No.10575016and No.10675161.The authors thank Dr.B.S.V .Patnaik for his comments and help.We also express our thanks to both anonymous referees for constructive comments and criticisms.

?1?E.Ott,Chaos in Dynamical Systems ?Cambridge University Press,New York,1993?,and references therein;Bai-lin Hao,Starting with Parabolas—An Introduction to Chaotic Dynam-ics ?Shanghai Scienti?c and Technological Education Publish-ing House,Shanghai,1993??in Chinese ?.

?2?M.C.Cross and P.C.Hohenberg,Rev.Mod.Phys.65,851?1993?.

?3?K.Kaneko,Theory and Applications of Coupled Map Lattices ?Wiley,New York,1993?.

?4?J.P.Cruth?eld and K.Kaneko,in Directions in Chaos ,edited by H.Bai-lin ?World Scienti?c,Singapore,1987?,p.272.?5?K.Kaneko,Physica D 34,1?1989?.?6?K.Kaneko,Physica D 37,60?1989?.?7?Chaos 2,279?1992?,focus issue on coupled map lattices in chaos,edited by K.Kaneko.

?8?K.Kaneko,Prog.Theor.Phys.72,480?1984?.

?9?E.J.Ding and Y .N.Lu,J.Phys.A 25,2897?1992?.?10?F.H.Willeboordse,Phys.Lett.A 183,187?1993?.?11?F.H.Willeboordse,Phys.Rev.E 65,026202?2002?.?12?F.H.Willeboordse,Phys.Rev.Lett.96,018702?2006?.?13?R.M.May,Nature ?London ?261,459?1976?.

?14?M.J.Feigenbaum,J.Stat.Phys.19,25?1978?;21,669

?1979?.

?15?A.Wolf,J.B.Swift,H.L.Swinney,and J.A.Vastano,Physica

D 16,285?1985?.

?16?T.S.Parker and L.O.Chua,Practical Numerical

Algorithms

FIG.9.?a ?Snapshot of the coupled map lattices at ?=3.5within the period-4regime and ?=0.3.The kink and pulse modes are em-phasized with the boxes.?b ?Bifurcation diagram of the CML and ?c ?the prediction from the mode analysis.

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for Chaotic Systems?Springer-Verlag,New York,1989?,Chap.

5.

?17?M.Zhan,G.Hu,Y.Zhang,and D.H.He,Phys.Rev.Lett.86, 1510?2001?.

?18?D.H.He,G.Hu,M.Zhan,and H.P.Lu,Physica D156,314

?2001?.

?19?A.Goryachev,H.Chate,and R.Kapral,Phys.Rev.Lett.80, 873?1998?.

?20?M.Zhan and R.Kapral,Phys.Rev.E72,046221?2005?.

PATTERNS WITH KINKS AND PULSES IN COUPLED…PHYSICAL REVIEW E76,036215?2007?

液力耦合器的工作原理

液力耦合器的工作原理 （一）液力耦器的结构： 液力耦合器是一种液力传动装置，又称液力联轴器。液力耦合器其结构主要由壳体、泵轮、涡轮三个部分。 泵轮和涡轮相对安装，统称为工作轮。在泵轮和涡轮上有径向排列的平直叶片，泵轮和涡轮互不接触。两者之间有一定的间隙（约 3mm 一 4mm ) ；泵轮与涡轮装合成一个整体后，其轴线断面一般为圆形，在其内腔中充满液压油。 （二）液力耦合器的安装方式： 液力耦合器的输入轴与电动机联在一起，随电动机的转动而转动，是液力耦合器的主动部分。涡轮和输出轴连接在一起，是液力耦合器的从动部分，与负载连在一起。 在安装时，液力耦合器安装在电动机与负载之间，通常由于负载较大，且与其它设备有联锁，采用将电机后移方案，在改造方案中需重新做电机的基础。 （三）液力耦合器的工作原理： 电动机运行时带动液力耦合器的壳体和泵轮一同转动，泵轮叶片内的液压油在泵轮的带动下随之一同旋转，在离心力的作用下，液压油被甩向泵轮叶片外缘处，并在外缘处冲向涡轮叶片，使涡轮在受到液压油冲击力而旋转；冲向涡轮叶片的液压油沿涡轮叶片向内缘流动，返回到泵轮内缘，然后又被泵轮再次甩向外缘。液压油就这样从泵轮流向涡轮，又从涡轮返回到泵轮而形成循环的液流。液力耦合器中的循环液压油，在从泵轮叶片内缘流向外缘的过程中，泵轮对其作功，其速度和动能逐渐增大；而在从涡轮叶片外缘流向内缘的过程中，液压油对涡轮作功，其速度和动能逐渐减小。液压油循环流动的产生，是泵轮和涡轮之间存在着转速差，使两轮叶片外缘处产生压力差。液力耦合器工作时，电动机的动能通过泵轮传给液压油，液压油在循环流动的过程中又将动能传给涡轮输出。液压油在循环流动的过程中，除受泵轮和涡轮之间的作用力之外，没有受到其他任何附加的外力。根据作用力与反作用力相等的原理，液压油作用在涡轮上的扭矩应等于泵轮作用在液压油上的扭矩，这就是液力耦合器的工作原理。 （四）、液力耦合器的调速方法： 液力耦合器在实际工作中的情形是：电动机驱动泵轮旋转，泵轮带动液压油进行旋转，涡轮即受到力矩的作用，在液压油量较小时，当其力矩不足于克服载的起步阻力矩，所以涡轮还不会随泵轮的转动而转动，增加液压油，作用在涡轮上的力矩随之增大，作用在涡轮上的力矩足以克服负载起步阻力而起步，其液压油传递的力矩与负载力矩相等时，转速随之稳定。负载的的力矩和转速成平方比，当随着液压油量的增加，输出力矩加大，涡轮的转速随之加大，达到调节转速的目的。 油液螺旋循环流动的流速 VT 保持恒定， VL 为泵轮和涡轮的相对线速度， VE 为泵轮出口速度， VR 为油液的合成速度。涡轮高速转动，即输出和输入的转速接近相同时小，而合成速度 VR 与泵轮出口速度之的夹角很大，这使液流对涡轮很小，这将使输出元件滑动，速度降低。当将油液量加大，相对速度 VL 和合成速度 VR 都很这就使液流对涡轮叶片的推力变得直到有足够的循环油液对涡轮产生足够的冲击力，输出转速变高。 （五）液力耦合器的转换效率： 液力耦合器调速原理表明，传动速度的改变，实质是机械功率调节的结果。因此液力耦合器输出转速的降低，实际是输出功率减小。在调速过程中，液力耦合器的原传动转速没有发生变化，假设负载转矩不变，原传动的机械功率也不变，那么输入与输出功率的差值功率那里去了呢，显然是被液力耦合器以热能形式损耗掉了。

液力耦合器常见故障及维护

液力耦合器原理、常见故障及处理 一、常见故障及处理 油泵不上油或油压太低或油压不稳定原因1.油泵损坏2.油泵调压阀失灵或调整不好3.油泵吸油管路不严，有空气进入4.吸油器堵塞5.油位太低，吸6.油压表损坏7.油管路堵塞处理1.修复或更换油泵2.重新调整或更换油泵调压阀使压力正常3.拧紧各螺栓使其密封4.清洗吸油口过滤5.加油至规定油位6.更换压力表7.清洗油管路2.油温过高原因1.冷却器堵塞或冷却水量不足2.风机负荷发生变动使偶合器过负荷处理1.清洗冷却器，加大冷却水量2.检查负荷情况，防止过负荷3.勺管虽能移动但不能正常调速原因无工作油进入处理1.修复或更换油泵2.重新调整或更换油泵调压阀使压力正常3.拧紧各螺栓使其密封4.清洗吸油口过滤器5.加油至规定油位6.更换压力表7.清洗油管路4.箱体振动原因1.安装精度过低2.基础刚性不足3.联轴节胶件损坏4.地脚螺栓松动处理1.重新安装校正2.加固或重新做基础3.更换橡胶件4.拧紧地脚螺丝 二、原理及故障排除： 1、原理： 液力偶合器工作原理液力偶合器相当于离心泵和涡轮机的组合，当电机通过液力偶合器输入轴驱动泵轮时，泵轮如一台离心泵，使工作腔中的工作油沿泵轮叶片流道向外缘流动，液流流出后，穿过泵轮和涡轮间的间隙，冲击涡轮叶片以驱动涡轮，使其象涡轮机一样把液

体动能转变为输出的机械能；然后，液体又经涡轮内缘流道回泵轮，开始下一次的循环，从而把电机的能量柔性地传递给工作机。二、液力偶合器的调速原理液力偶合器在转动时，工作油由供油泵从液力偶合器油箱吸油排出，经冷却器冷却后送至勺管壳体中的进油室，并经泵轮入油口进入工作腔。同时，工作腔中的油液从泵轮泄油孔泻入外壳，形成一个旋转油环，这样，就可通过液力偶合器的调速装置操纵勺管径向伸缩，任意改变外壳里油环的厚度，即改变工作腔中的油量，实现对输出转速的无级调节，勺管排出的油则通过排油器回到油箱。 2、故障现象及处理： （1）过热 1）、冷却器冷却水量不足，加大水量； 2）、箱体存油过多或少调节油量规定值； 3）、油泵滤芯堵塞清洗滤芯； 4）、转子泵损坏打不出油，换内外转子； 5）、安全阀溢流过多； 6)、弹簧太松上紧弹簧； 7)、密封损坏泄油换密封件； 8）、油路堵塞，清除。 （2）输出轴不转 1）、安全阀压力值太低，上紧弹簧； 2）、油路堵塞，清除；

液力偶合器和液力变矩器的结构与工作原理

液力偶合器和液力变矩器的结构与工作原 理 发布时间：2009-7-10 9:23:12 来源：点击数：5063 一、液力偶合器和液力变矩器的结构与工作原理 现代汽车上所用自动变速器，在结构上虽有差异，但其基本结构组成和工作原理却较为相似，前面已介绍了自动变速器主要由液力变矩器、变速齿轮机构、供油系统、自动换挡控制系统、自动换挡操纵装置等部分组成。本章将分别介绍自动变速器中各组成部分的常见结构和工作原理，为自动变速器的拆装和故障检修提供必要的基本知识。 汽车上所采用的液力传动装置通常有液力偶合器和液力变矩器两种，二者均属于液力传动，即通过液体的循环液动，利用液体动能的变化来传递动力。 （一）液力偶合器的结构与工作原理 1、液力偶合器的结构组成 液力偶合器是一种液力传动装置，又称液力联轴器。在不考虑机械损失的情况下，输出力矩与输入力矩相等。它的主要功能有两个方面，一是防止发动机过载，二是调节工作机构的转速。其结构主要由壳体、泵轮、涡轮三个部分组成，如图1所示。

图1 液力偶合器的基本构造 1-输入轴 2-泵轮叶轮 3-涡轮叶轮 4-轮出轴液力偶合器的壳体安装在发动机飞轮上，泵轮与壳体焊接在一起，随发动机曲轴的转动而转动，是液力偶合器的主动部分：涡轮和输出轴连接在一起，是液力偶合器的从动部分。泵轮和涡轮相对安装，统称为工作轮。在泵轮和涡轮上有径向排列的平直叶片，泵轮和涡轮互不接触。两者之间有一定的间隙（约3mm~4mm）；泵轮与涡轮装合成一个整体后，其轴线断面一般为圆形，在其内腔中充满液压油。 2、液力偶合器的工作原理 当发动机运转时，曲轴带动液力偶合器的壳体和泵轮一同转动，泵轮叶片内的液压油在泵轮的带动下随之一同旋转，在离心力的作用下，液压油被甩向泵轮叶片外缘处，并在外缘处冲向涡轮叶片，使涡轮在液压冲击力的作用下旋转；冲向涡轮叶片的液压油沿涡轮叶片向内缘流动，返回到泵轮内缘的液压油，又被泵轮再次甩向外缘。液压油就这样从泵轮流向涡轮，又从涡轮返回到泵轮

10大词类和句子成分的关系 已编辑知识讲解

十大词类与八大句子成分的关系 （1）十大词类： 据英语单词所表达的含义以及在句子中的作用，把英语单词分为10个类别，就是10大词类：名词、代词、数词、动词、副词、形容词、冠词、介词、连词、感叹词。 根据部分词类具有的共同特征，又将十大词类分为两大部分： 实词：名词、代词、数词、动词、副词、形容词。特征：具有完整的词义；能够在句子中独立充当句子成分。 虚词：冠词、介词、连词、感叹词。特征：没有完整的意思；不能够在句子中独立充当句子成分，必须和实词搭配，才能充当句子成分。 注意：1.介词为虚词，不能单独充当句子成分，必须同名词、代词、短语、句子构成介词短语，才能充当句子成分。介词短语在句中常作表语、定语、状语和补足语 2.动词分为系动词，助动词，情态动词和实义动词。其中实义动词又可分为谓语动词:时态语态语气 非谓语动词 To do :可以充当主、表、宾、补、定、状 Doing: 可以充当主、表、宾、补、定、状 Done: 可以充当表、补、定、状

（2）八大句子成分： 句子成分：组成英语句子的各个部分，叫做句子成分。 英语的句子最多由八个句子成分组成，即主语、谓语、宾语、表语、定语、状语、补足语以及同位语。 ★主语： 概念：句子的主体，发出动作的人或物，表示所说的是谁或是什么。 位置：主语一般在句首，特殊句型中在句末。 构成：由名词、代词或相当于名词的词、短语或从句充当。 例：Henry is a good boy.亨利是个好孩子。He ran away.他跑掉了。The second is yours. To learn a foreign language is not easy.学习一门外语不容易。 Driving to Beijing is not difficult.开车去北京不难。 What has happened proves that our policy is right. 发生的一切证明我们的政策是对的。 Whether we’ll go depends on the weather. 我们是否去要看天气。 ★谓语： 概念：说明主语的动作、特征、状态等的句子成分，叫做谓语。 位置：谓语动词通常位于主语之后，特殊句型位于主语之前。 构成：由动词或动词短语充当。 例如：We go to school from Monday to Friday. 我们周一至周五上学。 I shall go to see him tomorrow. 明天我要去看他。 He took part in the meeting last Saturday.他上周六参加了会议。 ★宾语： 概念：动词宾语是动作的承受者。及物动词以及相当于及物动词的短语后都必须带宾语。 介词之后的宾语叫介词宾语。 位置：动词宾语位于及物动词之后；介词宾语位于介词之后。 构成：名词、名词化的形容词、代词、数词、-ing形式、动词不定式和从句等均可作宾语。 例如：The teacher asked the students to finish the homework after class. 老师让学生们课下完成作业。 He wanted to buy that T-shirt.他想买那件T恤衫。They are having a party in the garden.他们正在花园里开聚会。 I don’t know when they will arrive.我不知道他们何时到达。I know three of them . ①有的动词可接双宾语： 英语中，有些及物动词可以接两个宾语，动作的承受者，即指物的叫做直接宾语，动作是为谁做的或是对谁做的，即指人的叫做间接宾语，这两个宾语称为“双宾语”。 例：Pass me the salt, please. 把盐递给我。the salt（直接宾语），me（间接宾语） They asked me to sing them a song. 他们要我给他们唱一支歌。a song（直接宾语），them（间接宾语）。 间接宾语后置：间接宾语也可以放在直接宾语的后面，这时候需要在间接宾语之前分别加两个介词：for或to.具体用哪一个介词，主要取决于句子的谓语动词。 例：I’ll lend you something to read. →I’ll lend something to read to you. 我要借点什么东西给你看。 I hope you will do me a favor.→I hope you will do a favor for me.我希望你能帮我做一件事。 以下这类双宾语动词如果间接宾语后置，要求在间接宾语之前加“to”。 give, show, send, bring, offer, read, pass, lend, leave, hand, tell, return, write, pay, throw, allow, wish, teach, promise, award等。 以下这类双宾语动词如果间接宾语后置，要求在间接宾语之前加“for”。 make, buy, do, fetch, get, paint, save, spare, order, cook, sing,等。 双宾语的注意事项 在下面情况下用to或for引起的短语比用间接宾语好 当直接宾语是人称代词时I’ll send it to you tomorrow. 比较（I’ll send you the book.）我明天给你送来。

液力耦合器原理word版

液力耦合器的模型与工作原理 液力耦合器是一种利用液体介质传递转速的机械设备，其主动输入轴端与原传动机相联结，从动输出轴端与负载轴端联结，通过调节液体介质的压力，使输出轴的转速得以改变。理想状态下，当压力趋于无穷大时，输出转速与输入转速相等，相当于钢性联轴器。当压力减小时，输出转速相应降低，连续改变介质压力，输出转速可以得到低于输入转速的无级调节。液力耦合器的功控调速原理与效率 根据液力耦合器的上述特点，可以等效为图1所示的模型 功率控制调速原理表明，传动速度的改变，实质是机械功率调节的结果。因此液力耦合器输出转速的降低，实际是输出功率减小。在调速过程中，液力耦合器的原传动转速没有发生变化，假设负载转矩不变，原传动的机械功率也不变，那么输入与输出功率的差值功率那里去了呢，显然是被液力耦合器以热能形式损耗掉了。因此，我们不能简单地认为液力偶合器调速是"丢转"，而实际是丢功率。设原传动功率为PM1，输出功率为PM2，损耗功率则为 液力偶合器是一种耗能型的机械调速装置，调速越深（转速越低）损耗越大，特别是恒转矩负载，由于原传动输入功率不变，损耗功率将转速损失成比例增大。对于风机泵类负载，由于负载转矩按转速平方率变化，原传动输入功率则按转速的平方率降低，损耗功率相对小一些，但输出功率是按转速的立方率减小，调速效率仍然很低。液力耦合器的调速效率曲线如图2所示，平均效率在50%左右。 1 / 1

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液力偶合器部分构件 它具有以下几个优点： 1.可以空载启动电动机，可控地逐步启动大负载。

2.给水泵无级调速时可以大量节省厂用耗电量。 3.可利用电机的最大扭矩启动负载。 4.隔离在动转过程中的冲击和震动。