CN101443644A

CN101443644A - Apparatus and method for detecting transmission belt wear and monitoring belt drive system performance

Info

Publication number: CN101443644A
Application number: CNA2007800119061A
Authority: CN
Inventors: 马茨·利波夫斯基
Original assignee: Individual
Current assignee: Individual
Priority date: 2006-03-29
Filing date: 2007-03-28
Publication date: 2009-05-27

Abstract

An apparatus and method with the capability to monitor endless belts and related belt drive systems by non-contact sensors for wear or an anomalous function, determining the state of belt drive system and detecting early stages of belt and system failure. A sensing unit featuring one or several independent sensor elements is placed adjacent to or in proximity of the belt, thereby monitoring several simultaneously occurring normal modes of operation of the belt. The sensor can determine soundness of the whole timing drive continuously by processing the collected signal and detecting structural damage. The collected data is processed by a microcontroller integrated with the sensor. The apparatus and method for monitoring endless belts for wear or anomalous function uses a non- contacting capacitor array comprised of one or several sensing elements placed adjacent to or in proximity of the belt and connected to electronic circuitry that is particularly adapted to sense the dynamic capacitance change coupled with electrocapacitive and piezoelectric effects exhibited by the belt. The apparatus is further capable of monitoring drive components related to the belt by detecting if the belt is affected by the anomalous function of the related components. The sensor continuously monitors the belt during normal operation of the belt drive. The sensor is particularly adapted to sense the belts currently used in workshop, industrial and automotive applications and feature a polymer matrix with a fiber cord load bearing core.

Description

The apparatus and method that are used to detect the driving-belt wearing and tearing and monitor the belt transmission system performance

Background of invention

In the power transmission field, tape handler is the preferred components that connects rotating element.They generally are divided into two big classes traditionally: asynchronous and synchronous belt drive mechanism.In vehicle, use this two class widely.Non-synchronous drives is the preferred components that is used to drive such as the such part of water pump, compressor of air conditioner, power steering pump and alternator unit.The synchronous drive mechanism of so-called timing gear train is the preferred components that is used to drive the overhead cam axle system, and is widely used in and is driven assembly in the internal combustion engine and need synchronous place.An example that has shown this gear train among Fig. 1.

Timing belt generally is the compound of glass fibre, woven fabric, rubber and other various polymkeric substance.All these materials all show piezoelectric property: they can produce electric charge in distortion.Under normal operating condition, during by sprocket and pulley, band is by tensile force and bending force distortion at tape running.These distortion have produced electric charge.Because the high relatively resistance of carrying material, the time long enough that electric charge exists is so that can be detected.Proportional by electric charge and tensile force that piezoelectric effect produces.This specific character successfully is applied in force transducer and the accelerometer.

The present invention described herein is applicable to this gear train of two types, but is specially adapted to regularly gear train.Band is more more economical than the miscellaneous part (being chain or gear drive) that uses, less complicated and more effective.The major defect of band is be difficult to determine their life-span or be with the point of possible incipient fault in the life-span at vehicle.Up to now, vision-based detection is the sole mode of the state of test strip gear train and associated component thereof.Yet this is to bother very much and unpractical process.Regularly gear train is because the easily weakness of polluting thereby the operation of sealing ground usually, and removes the normally unusual operation of effort of shell before vision-based detection.In addition, for human eye the band and the infringement of other assemblies normally sightless, it is inefficent that vision-based detection proves.In addition, the fault of band can cause vehicle or gear train to become can not operating, and because attribute with higher compression ratios of Modern Internal-Combustion Engine, when fault caused asynchronous and valve train and piston collisions dangerous, out of order band caused internal combustion engine to be subjected to very big infringement usually.

Although timing belt has utilized the tooth geometry of improved material and enhancing to obtain sizable development, for whole timing kinematic train, structural development does not solve the problem of life expectancy.Uncertain and the higher maintenance cost of tape handler life expectancy and the consumer's who thereupon comes the dissatisfied manufacturers of engines that forces is calculated with sizable margin of safety when this gear train of design and use.As a result, band is made much wide than needs, and the mileage of the recommendation that changes of band is made as lower modestly.The uncertainty in band serviceable life forced engine manufacturers and regularly the gear train deviser consider to return and use chain and do not use band.Trend towards maintenance-free engine on the market has been strengthened this consideration especially.However, the very unwilling chain that transfers to of manufacturers of engines, and the trial of being undertaken for many years by any possible mode solves this difficult problem.

Prior art demonstrates about claiming the positive activity of some inventions that can handle this problem.Existing many viewpoints can not address this problem, and unactual to industrialization to a great extent.A large amount of schemes does not cause investor's attention, because they are not enough to prove related extra cost or design challenge.This is a class scheme of the variation design of requirement band.U.S. Pat 6181239 and U.S. Pat 6523400 proposes following a kind of scheme, promptly wherein detects belt wear by being embedded in the line in the band or the inductance or the electric capacity damaged or that change of metal construction.For the those skilled in the art that make band, this scheme is unpractical.In band, embed metal construction and will mean and depart from manufacture method greatly, and for this metal construction to influence with whole endurance, introduced great uncertainty.Band manufacturer all tends to very conservative scheme for any design variation, makes that the enforcement of such scheme is very unreliable.And the cost relevant with this plan will make product very expensive.Another shortcoming is that this scheme only is used for the band that OEM installs.On automotive industry aftermarket, make by several manufacturers usually with the band that the specific engines gear train uses.The band that is used to serve usually from install by OEM with different manufacturers.

Recognize that also invention (wherein typical case is a U.S. Pat 6569046) requirement use optics or mechanical switch based on machinery, photoelectricity or on/off switch sensing device respond damaged sideslip tracking of being with, U.S. Pat 4626230 requires to use this switch to detect the out of order tooth or the gear teeth, and all these does not reach target.These devices are easy to be polluted, and are easy to the warning that makes mistake or become unreliable, because their keep static and only just are triggered after protected band infringement.In addition, because can not simulate required input, so can not check the function of this device.Because the possibility of false alarm, they must be calibrated, with serious confusion in the system of response as generation when band has significantly broken down.This is hardly to driver's warning or to warning.

Summary of the invention

Detect described in the present invention compared to existing technology of the breakage of driving-belt and infringement those by the noncontact mode significant improvement is provided, because it provides by detecting the parts of the performance that monitors gear train to any influence of band or harmful input and to any physics or the structural damage of band.For any those of skill in the art in this area, if do not having to work the same durable of band that uses in the timing system obviously shown in Figure 1 under the top condition of unusual input value with chain.Most of situations that band breaks down too early are because unusual, after as the failed row that has suffered coupled assembly at band being, perhaps, perhaps be exposed to the outside dirt as penetrating dust, ice, water and the flag that leaks shell by the fluid contamination normally used oil in engine and industrial machine, cooling medium and other liquors.In essence, the present invention can be used for monitoring driving-belt in case the generation of any this anomalous effects.From existing another advantage implementing to obtain of the present invention is that tape handler is not needed to carry out design variation, and this is opposite with invention described in the prior art.The invention provides a reliable system determines the life-span of tape handler and can make the designer take multiple strategy to how improving the total system quality.

In having the new band of uniform strength, piezoelectric charge evenly distributes.New sensor is relatively sensitiveer for the variation of electric density, does not therefore have great changes in output signal.When band wore and tore owing to use, the some parts of band became more weak, and shows bigger deformation strain when applying load in the power operation process, and this just causes the partial charge density of piezoelectric effect bigger in this region and Geng Gao thereupon.This new sensor causes signal amplitude to increase to this higher partial charge.Thereby signal amplitude is big more, and described band is weak more.Described sensor also detects the variation of the capacitance characteristic that the dynamic change by the dielectric property of described band causes.

The invention is characterized in the non-contact sensor that couples with MPU (microprocessing unit).Described sensor utilizes one or several capacitance detecting element to operate, and described one or several capacitance detecting element is coupled into a circuit and is designed to detect the variation or the changes in capacitance of specific inductive capacity.The electrostatic capacitance that piezoelectric effect caused that causes by described band when described sensor also detects in the course of normal operation of system structured material when described band tensioning by the capacitance detecting element.In the operating process of described tape handler, the piezoelectric property of described band produces electric charge or the similar static that is accumulated in the described band, the ratio that is deformed into that itself and described band are subjected to.Because will having bigger distortion and therefore produce from described sensor, the band portion of wearing and tearing changes the higher charge of higher signal level into, so can utilize of the indication of described effect as belt wear.Place described detecting element in the following manner, promptly it produces and the key feature of described band and the corresponding signal response of specific critical mode that shows at band and described tape handler described in the operating process.The pattern that the typical case detects is: instantaneous RPM and every rotation signal event once that the span vibration of basic band feature, nature and meshing frequency, band tooth cause.Cause the general position on tape of the belt wear that damages to begin, sensor will detect this position and produce every rotating signal incident (being called OPRSE afterwards) with.

Pollution will cause specific inductive capacity and/or electrostatic capacitance and the variation permanent or behavior of semipermanent piezoelectricity by the band of any detecting element record, and cause the signal threshold value overall variation.The primary fault of any coupling assembly will cause the variation of belt tension.Tension variation will cause in course of normal operation the skew of the vibration performance that the span by described band shows again.In addition, the torsional characteristics of described tape handler also changes.The variation of feature can be directly and the quantitative increase of belt tension or reduce to be related, and these any those of skill in the art for the band transmission field are conspicuous.Can handle by the signal processing method of any amount by the signal that testing circuit obtains.Any device that can carry out data aggregation and signal analysis can further be regulated and be coupled to signal based on simulation.Yet optimum of the present invention is embodied as independent device, and wherein DSP (digital signal processing) algorithm of carrying out by the MPU (microprocessing unit) that is embedded in the sensor construction is analyzed described simulating signal.Final data is stored on the plate of sensor construction, and according to terminal user's strategy, can further analyze these data by the algorithm in outside PLC (programmable logic controller (PLC)) or the vehicle control device, perhaps its storage is used to be transferred to central database.

[11] this function will provide several advantages to user (OEM), as: the non-linear scheme that allows maintenance intervals, promptly when band or other when regularly transmission components need repairing, before arriving predetermined mileage, vehicle sends signal (this is especially useful as rescue, law compulsion or hackney vehicle for the vehicle with strict work period).If especially during the guarantee period, break down, before severe impairment or afunction generation, detect the early signal of transmission fault and can save bigger cost.According to the data of collecting, the user can produce response initiatively, i.e. issue maintenance report.According to the data of collecting, it is what has formed regularly the service lifetime of gear train and the tricks of the trade that how to design gear train best that the user can produce.It is narrower that band can be done, and saves several millimeters space in the place of taking notice of the space saving thus.As the instrument sold on the market time, the present invention can reduce or eliminate the insecure this viewpoint of current tape handler, makes the vehicle final user relieved.Advantage above-mentioned also can be directly used in industrial belt transmission system.

Describe in detail with preferred embodiment

[12] in conjunction with following accompanying drawing, the present invention may be better understood from following detailed and preferred implementation.

Description of drawings

[13] Fig. 1 has shown the front elevation of pick-up unit tape handler in position;

[14] Fig. 2 has shown the sectional view of pick-up unit and adjacent band structure;

[15] Fig. 3 has shown the sectional view of typical band structure;

[16] Fig. 4 has shown the side view of typical band structure;

[17] Fig. 5 has shown the front elevation of band, and it has been described when typical case's band and has demonstrated the fibre core of exposure and the typical fault mode during fault of construction;

[18] Fig. 6 has shown the side view of band, and it has described the fault of single band toothing;

Fig. 7 has shown the front elevation of tape handler, and it has described the typical vibration mode in the band span between two assemblies;

Fig. 8 has shown the sectional view of typical band structure, and its preferred vertical of having described detecting element is placed;

Fig. 9 has shown the side view of band, and its preferred vertical of having described detecting element is placed;

Figure 10 has shown the sectional view of typical band structure, and its preferred parallel of having described detecting element is placed;

Figure 11 has shown the side view of band, and its preferred parallel of having described detecting element is placed;

Figure 12 has shown the sectional view of typical band structure, and its preferred levels of having described detecting element is placed;

Figure 13 has shown the side view of band, and its preferred levels of having described detecting element is placed;

Figure 14 is the front elevation that shows the preferable configuration method of detecting element;

Figure 15 is the front elevation that shows the preferable configuration method of detecting element;

Figure 16 is the front elevation that shows the preferable configuration method of detecting element;

Figure 17 is the front elevation that shows the preferable configuration method of detecting element;

Figure 18 is the front elevation that shows the preferred detection element;

Figure 19 has shown the typical regularly front elevation of the part of gear train of the complete pick-up unit with example preferred embodiment;

Figure 20 shown with Figure 19 in the auxiliary view of identical pick-up unit;

Figure 21 has shown the sectional view of band, and how its optimum position and element of having described detecting element/pick device is connected with circuit;

Figure 22 has shown block diagram, its described by the signal path of the primary clustering of pick-up unit and with the communication of the device of sensor outside;

Figure 23 has shown the signal that produces when the 55Hz span vibration;

Figure 24 has shown the frequency spectrum of the signal among Figure 23;

Figure 25 has shown the signal that produces when the 30Hz span vibration;

Figure 26 has shown the frequency spectrum of the signal among Figure 25;

Figure 27 has shown the signal that is used to pick up an incident of every rotation;

Figure 28 has shown the signal that the band dyke dashes;

Figure 29 has shown the side view of band, and it has described the xsect of detecting element;

Figure 30 has shown the side view of band, and its preferred vertical of having described two detecting elements that utilize signal cancellation is placed;

Figure 31 has shown the signal that the band dyke dashes and has been with the influence of polluting.

The description of preferred implementation

Feature of the present invention is a kind of pick-up unit and signal analysis method, and it is particularly useful for describing the operating conditions of tape handler and band is worked as in prediction and/or when its associated component should replace, to avoid the gear train fault.In addition, the invention is characterized in electronic circuit 51 shown in Figure 22 and detecting element 36, it is by operating with the capacitive element of electric capacity (electrocapacitive) and piezoelectric property coupling, just can collect signal data without contact zones.Detecting element 36 can pass through static structures (i.e. Dai shell) and detect band.The attribute of this detection makes it be particularly useful for detecting dynamic harmonic and transient event from being with of passing through.Any those of skill in the art in this area of electric capacity, electric capacity and piezoelectric detection circuit can realize described circuit by a plurality of modes.Open source literature Capacitive SensorsDesign and Applications, Larry K Baxter, IEEE, Piscataway, NJ are the better sources of sort circuit example.Preferably,, but for the present invention, can use any capacitive detection circuit with appropriate characteristics because its element can be easy to be integrated into the signal circuit of mixing at the transistorized new departure of use MOS (metal-oxide semiconductor (MOS)) described in the disclosure document.This partial circuit is called mimic channel 51.The detecting element that is coupled in the mimic channel is arranged on the object tape structure periphery, to produce desirable signal input best.Detecting element 51 is made up of the generation specific capacitor of two adjacent settings and the electrode that projects capacitance field.Described electrode is towards the band target, so that the dielectric property that band changes will influence described capacitance field in the following manner, promptly feasible electric capacity by the mimic channel 51 detected electrodes that are coupled changes.Described detecting element also detects accumulation capacitance charge on tape by the mode of induction coupling, and this is the result of the piezoelectric characteristic of carrying material compound.

As shown in Fig. 8 and 9, will cause signal response at the toothing 21 that passes through across the detecting element 36 of band structure setting.The signal response that has shown described element among Figure 28, its middle distance 80 is corresponding to 17 space width.

For the present invention, as Fig. 8,9 and two or more

detecting elements

36,38 of being provided with of a plurality of band space widths 16 ground, interval shown in Figure 13 will have the effect that increases described signal response by tooth.

As shown in Figure 19 and 20 on the main direction of Tape movement machine-direction oriented detecting element 37 will mainly cause (at band span 14 as shown in Figure 7 laterally move 27) signal response.Laterally moving generally is the result of span vibration nature or that bring out.Figure 23 has shown the type signal response of the natural span vibration 27 with vibration period 84 and amplitude 73 shown in Fig. 7.Figure 24 has shown the frequency spectrum of described signal, wherein the free-running frequency 71 of 74 expression band spans 14.Detecting element 37 with the length that equals three or more band space widths 16 is not subjected to influence by toothed, therefore will be as the filtrator of the engagement signal (meshing signal) of being with tooth to produce.Move 26 if the frequency 70 relevant with engagement is present in the horizontal of band span 14, then detecting element will only detect this frequency 70 relevant with engagement.

As shown in Figure 21, use multiplexer switch 50 to be connected by several detecting

elements

36,37 with 38 sensors of forming with mimic channel 51.Described multiplexer switch is by the MPU53 shown in Figure 22 control and can be according to the needs of the DSP strategy that uses from each detecting

element

36,37 and 38 separately, integrally or combination in any ground sampled signal.

As shown in Figure 30, two detecting elements 36 with following special layout be positioned at band relatively or same side: promptly they be spaced apart half interband increment apart from 45, thereby one in the face of tooth tip, and another is in the face of root.As shown in Figure 30, the attribute by

signal

46,47 cancels each other out 81, and this detecting element structure causes by significantly the reducing of the signal response that causes by band tooth 20, and wherein chart 81 illustrates this counteracting.When sensor was checked OPRSE (every rotation signal event once) or checked inner structure infringement (i.e. Dai wearing and tearing), this was especially favourable.OPRSE appears when detecting owing to the infringement that causes with 17 fault of construction or wearing and tearing.In most cases, the band infringement begins at a point, and in further operating period, the band infringement will be expanded, and cause the entire belt fault.OPRSE is the signal that breaks down and should replace rapidly with 17.Fig. 5 has shown two kinds of band infringements being represented by OPRSE usually: incipient cord breakage 22 and polymer deficiency 23.Fig. 6 shown since the toothing 24 of shortcoming or the tooth 25 that breaks cause to 17 infringement.The infringement of these types shows as the clear signal event that can distinguish in signal trace.An example that has shown described signal trace among Figure 27, wherein signal peak 79 representative is with the described OPRSE at a last specified point place, and distance 78 representatives are through one of described detecting element complete band rotation.With threshold level relatively before or after, the signal peak on a plurality of cycles 79 can be added and, to avoid spurious signal and false alarm.

If in the gear train shown in Fig. 1, use with 17 by such as the oil that stay residue on tape, engine coolant or the such fluid contamination of fluid contamination thing arbitrarily, cause its dielectric and/or capacitance characteristic to take place fully to change, then sensor module will detect the existence of described fluid and be recorded in skew in the whole signal threshold value as shown in Figure 31, the signal level of measurement before wherein 82 expressions are polluted, 83 are illustrated in the signal level of measuring after the pollution.

Fig. 1 has shown main use of the present invention as the monitoring arrangement that is used for tape handler, and described tape handler is generally used for keeping the synchronism of internal combustion engine cam and is commonly referred to regularly gear train.In described tape handler, new sensor 30 is provided with near camshaft sprocket 7.In this position, the best assembling of sensor 30, thus monitor gear train, and detect with 17 any unusual input and detect infringement to band.Because sensor 30 is operated by the noncontact mode,, thereby do not disturb mobile band structure 17 so it is spaced apart with

sufficient gap

34 and 35 as shown in Figure 2.As shown in frame of broken lines among Figure 22, sensor 30 has all detecting

element

36,37,38 and electronic installations that are embedded in its structure, and this can make described sensor automatically operate.Sensor 30 is connected with the vehicle startup machine controller and uses the slave unit of the vehicle motor controller 58 of deciding usually and pass through distribution 31 or wireless antenna 32 and controller communication.Signal path is as follows: detecting element 36 detects by electric field 72 and describedly is with 17.Element 36 is coupled to mimic channel 51 by the multiplexing components shown in Figure 21 50.Described circuit produces simulating signal 61, and this simulating signal 61 is converted to digital data stream by A/D converter 52 and is stored among the microprocessing unit MPU53.MPU53 carries out digital signal processing DSP by embedded algorithm.Suitable DSP is known for any those of skill in the art in Digital Signal Analysis field.

Sensor module 30 can be used as a separate unit operation with embedded battery power supply, and this can make operation be independent of vehicle power supply.This selection is particularly useful for after sale service and uses.

The electronic installation that is combined in the sensor module 30 uses a series of automobile communication agreement (as LIN (local interlinkage net) or CAN (controller area net) 57, the perhaps derivant of this agreement (Figure 22)) by wired or wireless mode and vehicle communication.

The electronic installation that is combined in the sensor module 30 has the embedded microcontroller 53 with the algorithm pre-programmed, if band or gear train are about to break down, this microcontroller 53 can independently be judged according to detected signal.

Sensor module 30 can be used as the system monitoring instrument, and wherein said sensor can be periodically or given the vehicle control device ECU58 timing transmission performance parameter that transmission is stored according to demand, as belt tension or camshaft torsional characteristics.Described performance parameter can be transferred to the vehicular manufacturer with wireless mode under vehicle is equipped with the situation of communication uplink, perhaps described performance parameter can download to vehicle OEM59 data bank in predetermined usually maintenance place.

Except the surface area of adjusting element, also under the condition of detection length of realizing ideal and capacitance, make described detecting element in a plurality of modes, described conditional decision the sensitivity of detecting element to capacity effect.Described primary detecting element is made up of two metal constructions of the predeterminable range that is spaced apart from each other by dielectric component.Figure 14 has shown that by two parallel

copper tracing wires

40 and 41 detecting elements of forming described

trace

40 and 41 uses the electronics industry method of manufacturing circuit board of standard to be etched on the PCB (printed circuit board (PCB)) 39.Figure 15 has shown how the copper tracing wire 40 that is surrounded by the copper tracing wire 41 that is shaped as U-shaped is keeping increasing described detecting element electric capacity in the less trace.Figure 16 has shown and has been shaped as horseshoe-shaped two copper tracing wires 40 and 41.Figure 17 has shown by each all being coated with dielectric two

distributions

40 and 41 and has been screwed in another mode of coming together to form detecting element.The thickness of distribution sheath has defined the distance between two distributions forming electrode.Figure 29 has shown two sheet metals or the bar 42 of the relative both sides that are soldered to dielectric substance, wherein the distance between them equal object tape 17 band space widths distance 16 half or all.This detecting element structure is suitable for detecting the band toothing that passes through.

Preferable methods embodiment

The analog AC signal of detecting

element

36,37 that is connected with

mimic channel

51 and 38 output continuous modulation as shown in Figure 28.Described signal is converted into binary signal and is transferred to storage and the computing unit MPU53 that couples with mimic channel 51.According to described signal, in conjunction with the instantaneous band transmission speed of DSP algorithm computation.

The analog AC signal of the detecting element 37 continuous modulation of output as shown in Figure 23 and 25 that are connected with mimic channel 51.Described signal is converted into binary signal and is transferred to storage and the computing unit MPU53 that couples with mimic channel 51.According to described signal, the MPU53 that is combined with the DSP algorithm calculates the free-running frequency 74 of the specific band span of close described detecting element.For any those of skill in the art of band transmission field, the frequency of being calculated 74 is relevant with the tension level in the band span.Therefore, represent the skew of belt tension as the variation of Figure 26 medium frequency 76.Monitor described frequency provides the tension level that is used for detecting band whether to be displaced to the mode outside the predetermined operational thresholds.In addition, if the signal list shown in Figure 25 reveals extra frequency content, as shown in besieged part 77, described signal just represents that the band span that additionally causes moves.Described frequency content is relevant with sprocket engaging piece 26 with band usually, and identical with the frequency signal of measuring that passes through band tooth 20.Because impose on the wrong tension force of described band structure, above-mentioned phenomenon will worsen because of the dislocation in the described engaging piece 26.The another part that combines the MPU53 of DSP algorithm is designed to monitor the generation of described frequency and amplitude and described signal and predetermined operating limit is compared.If described signal threshold value surpasses described operating limit, the MPU53 that is embedded with algorithm produces a fault band transmission and reports to the police.

Calculate (DSP) camshaft reverse the phasing degree time utilize the signal that produces by by tooth 20.With described data compilation is the transmission torsional characteristics, and is used to diagnose the variation of the operating conditions of tape handler.

Be embedded in MPU53 in the sensor 30 and have the DSP algorithm of combination, described DSP algorithm monitors is from detecting

element

36,37, and 38 and 42 signal is also determined whether object tape 17 or tape handler show and can be caused with 17 or the operation behavior of tape handler fault.If will produce fault, described algorithm produces and is used for the failure code that this vehicle of driver/operator should keep in repair immediately, perhaps described failure code is sent to vehicle OEM or maintenance supplier, further to move.

Sensor 30 is connected with vehicle wire harness by connector 33.Embedded algorithm uses digital network communications protocol LIN/CAN57 by bunch and vehicle ECU (control unit of engine) communication.

Claims

1. determine composition polymer and the physics of fabric strip and the method for structural condition mobile under normal operating condition for one kind, comprising:

When moving, band portion detects the transient behavior dielectric and the capacitance characteristic of described band portion by capacitance detecting device, with generation transient behavior capacitance signal,

From the described transient behavior capacitance signal of simultaneous any electrostatic capacitance Signal Separation by at least one detecting element generation of described pick-up unit,

The threshold level of described transient behavior capacitance signal and dynamic capacity signal is compared, and

Periodically break through the described threshold level of dynamic capacity signal in response to described transient behavior capacitance signal, excite output signal.

2. method according to claim 1, wherein before exciting described output signal, preset time on the cycle the described transient behavior capacitance signal to the described threshold level of breaking through the dynamic capacity signal sum up.

3. method according to claim 1, wherein said output signal is an alerting signal.

4. capacitance detecting device, it comprises and being suitable for and the normal composition polymer that moves and at least one detecting element of the adjacent setting of fabric strip,

When described band moves past described pick-up unit, described detecting element be suitable for producing in response to the dynamic change of the dielectric property of described band periodically variable electric signal and

Electricity calculating unit, this electricity calculating unit comprise at least one analogue-to-digital converters, microprocessor and the parts that output signal is provided in response to the threshold level of the dynamic change that periodically breaks through described band dielectric property.

5. capacitance detecting device according to claim 4 wherein has a plurality of detecting elements with at least one side gathering on described band.

6. capacitance detecting device according to claim 4 wherein along the position on the moving direction of described band, is adjacent to be provided with at interval a plurality of detecting elements with described band.

7. capacitance detecting device according to claim 4, wherein said output signal is an alerting signal.

8. method of determining under normal operating condition the physical condition of the composition polymer that moves and fabric strip comprises:

When moving, band portion detects the transient behavior electrostatic field of described band portion by pick-up unit, with generation transient behavior signal,

From the described transient behavior signal of simultaneous any electrostatic signal separation by at least one detecting element generation of described pick-up unit,

The threshold level of described transient behavior signal and Dynamic Signal is compared, and

Described threshold level in response to described transient behavior signal period property ground breakthrough Dynamic Signal excites output signal.

9. method according to claim 8, wherein before exciting described output signal, preset time on the cycle the described transient behavior signal to the described threshold level of breaking through Dynamic Signal sum up.

10. method according to claim 8, wherein said output signal is an alerting signal.

11. a pick-up unit comprises being suitable for and the normal composition polymer that moves and at least one detecting element of the adjacent setting of fabric strip,

When described band moves past described pick-up unit, described detecting element be suitable for producing in response to the dynamic change of the electrostatic field of described band periodically variable electric signal and

The electricity calculating unit comprises at least one analogue-to-digital converters, microprocessor and the parts that output signal is provided in response to the threshold level of the dynamic change that periodically breaks through described belts electrical conductivity characteristic.

12. pick-up unit according to claim 11 wherein has a plurality of detecting elements with at least one side gathering on described band.

13. pick-up unit according to claim 11 wherein along the position on the moving direction of described band, is adjacent to be provided with at interval a plurality of detecting elements with described band.

14. pick-up unit according to claim 11, wherein said output signal is an alerting signal.

15. determine composition polymer and the physical condition of fabric strip and the method for wearing and tearing mobile under normal operating condition, comprising for one kind:

When band portion moves, detect the electric charge that produces by the piezoelectricity coupling that exists in the described band portion, thereby produce signal in response to the instantaneous electric density of band portion by the noncontact charge sensor.

16. method according to claim 15, wherein said signal and described electric density are proportional.

17. method according to claim 15 wherein before exciting output signal, sums up the signal of the breakthrough certain threshold level level that produces on the selected time cycle.

18. method according to claim 17, wherein said output signal is an alerting signal.

19. pick-up unit, comprise with at least one conductivity detection element of aliging of moving direction, with vertical at least one the conductivity detection element of the moving direction of described band and at least one the conductivity detection element that is positioned at the plane parallel with the moving direction of described band

Described pick-up unit is configured to surround at least in part a part that moves past described band therebetween.