Belt drive and method for monitoring such a belt drive

Abstract

A belt drive and a method for the monitoring thereof allows conclusions to be drawn regarding loads to which the belt has been subjected over its past usage period. The method includes a rotatably mounted disc and a belt which is deflected at the disc. The belt and the disc are equipped with a marking and are positioned with respect to each other such that the markings are directly opposite each other in a trigger position when the belt circulates around the disc. The trigger position is recorded by a monitoring device, which emits a signal when the markings are located in the trigger position. The number of signals triggered over a time period is recorded. The loads to which the belt or the disc have been subjected during the time period is determined while taking into consideration relevant influencing variables.

Claims

1. A method for monitoring a belt drive, comprising: providing a first marking comprising a monitoring device on a rotatably mounted disc, the first marking being offset from the center of the disc; providing a second marking on a belt which is deflected at the disc; wherein the first marking and the second marking are positioned on the disc and the belt, respectively, such that during circulation of the belt around the disc, the first marking and the second marking reach a trigger position in which the first marking and the second marking are in line with a center of the disc, wherein a rotational axis of the disc runs through the center of the disc; a) recording, by the monitoring device, when the trigger position is reached, wherein the monitoring device emits a signal when the markings are located in the trigger position; b) recording a number of signals emitted by the monitoring device over a certain past time period; and c) determining loads to which the belt or the disc have been subjected to during the past time period based on the number of signals emitted by the monitoring device corresponding to a number of circulations of the belt, and taking into consideration relevant influencing variables.

2. The method according to claim 1, wherein in step c), material properties of the belt and the disc, geometries of the belt and the disc, friction conditions, prevailing static or dynamic forces, elongation or deformations of the belt when circulating around the disc, temperatures, environmental atmosphere or power consumption of a drive motor provided to drive the belt drive are considered as influencing variables.

3. The method according to claim 1, wherein, based on the determined loads and taking into consideration the influencing variables, a prediction is made by an evaluation device regarding an expected service life of the belt or the disc.

4. The method according to claim 1, wherein the number of signals recorded in step b) or the loads determined in step c) are compared with a set value, and, in a case where the recorded number of signals or the determined load deviates from the respective set value, a notification regarding the necessity of a maintenance operation or an emergency stop is triggered.

5. The method according to claim 1, wherein at least one of the first marking or the second marking bears information regarding the properties of the belt or the disc, wherein the information is read from the monitoring device and considered when determining the loads.

6. A belt drive comprising: a rotatably mounted disc bearing a first marking comprising a monitoring device, the first marking being offset from the center of the disc, and a belt deflected at the disc, the belt bearing a second marking, wherein the first marking and the second marking are positioned on the disc and the belt, respectively, such that during circulation of the belt around the disc, the first marking and the second marking reach a trigger position in which the first marking and the second marking are in line with a center of the disc, wherein a rotational axis of the disc runs through the center of the disc; and wherein the monitoring device is configured to emit a signal when the markings of the disc and the belt are located in the trigger position.

7. The belt drive according to claim 6, wherein the monitoring device is coupled to an evaluation device which counts a number of signals emitted by the monitoring device.

8. The belt drive according to claim 7, wherein the evaluation device is configured to record the number of signals emitted by the monitoring device and, based on the number of signals and taking into consideration further influencing variables, determines loads to which the belt or the disc have been subjected to.

9. The belt drive according to claim 8, wherein the evaluation device is coupled to the monitoring device for reading the information borne by at least one of the first marking and the second marking.

10. The belt drive according to claim 6, wherein the second marking is an identification means which bears information regarding the belt.

11. The belt drive according to claim 10, wherein at least one of the first marking and the second marking is an RFID chip.

12. The belt drive according to claim 10, wherein a case where the belt is a toothed belt or synchronous belt, the identification means is arranged above a centre of teeth of the belt and below a tensile member in elastic embedding material of the belt or on a rear side of the belt; in a case where the belt is a V-belt, the identification means is arranged below the tensile member or on the rear side of the belt; or in a case where the belt is a flat belt, the identification means is arranged between layers of the belt.

13. The belt drive according to claim 6, wherein at least one of the first marking or the second marking is formed as an active element which records one or a plurality of properties of the belt or the disc in operation and delivers the properties to the monitoring device when the trigger position has been reached.

14. The belt drive according to claim 6, wherein the monitoring device is connected to a device for remote data transmission.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Exemplary embodiments are explained in more detail below on the basis of a drawing. The figures thereof schematically show in each case:

(2) FIG. 1 the principle structure of a belt drive used as a linear axle drive;

(3) FIG. 2 the principle structure of a so-called omega drive ( drive) Q;

(4) FIG. 3 a belt drive;

(5) FIG. 4 a section of a belt used in the belt drive according to FIG. 3 in a side view;

(6) FIG. 5 the belt section according to FIG. 4 in a plan view of its back.

DETAILED DESCRIPTION

(7) Belt drives are typically used in linear axle drives. In the simplest case, a linear drive unit L, as depicted in FIG. 1, consists of a drive disc M, a deflection disc U, a moveable slide S and the belt R to which the slide S is coupled. The slide S is moved back and forth in continuous change by means of the belt R between its two end positions.

(8) A further example for a belt drive Q is the so-called omega drive ( drive) depicted in FIG. 2. The drive disc M of the motor and two deflection discs U formed as rollers are attached to a moveable slide S.

(9) In FIG. 3 it is demonstrated on the basis of a different drive unit E how a belt drive according to the invention may be designed and how the monitoring according to the invention of the belt drive (=drive unit L) may be carried out. The drive unit E according to FIG. 3 is suitable for example for transferring a drive torque applied by the motor disc M to a drive, not shown here, coupled to the deflection disc U.

(10) The belt R is formed as a conventional toothed belt.

(11) The drive disc M and the deflection disc U are accordingly provided on their circumferential surfaces coming into contact with the teeth Z of the belt R with a toothing formed corresponding to the geometry and arrangement of the teeth Z of the belt R such that the teeth Z of the belt R engage in a positive-locking manner into the toothing of the discs U, M when they circulate around the discs U, M.

(12) The belt R loops around the disc U, M equally sized in the present case by respectively 180.

(13) An RFID chip K1 is arranged in the belt R as a marking. The RFID chip K1 in this regard sits in a recess which has been drilled into one of the teeth Z of the belt R after the belt R has been assembled. The recess with the RFID chip K1 is in this regard arranged in the elastic embedding material of the belt R in the region of the foot of the tooth Z, i.e. between the centre MZ of the tooth Z and the tensile member T of the belt R.

(14) The RFID chip K1 bears for example information regarding the type, the manufacture date, the date of the entry into use as well as the materials used for the belt and the like.

(15) A sensor K2 is arranged in the drive disc M as a marking. The sensor K2 is a device by means of which the information stored on the RFID chip K1 used as the marking of the belt R may be read out.

(16) The sensor K2 is arranged in an edge region of the disc M close to a gap C between two teeth Zs1, Zs2 of the disc U. If the tooth Z of the belt R provided with the RFID chip K1 is dipped into the gap C, the RFID chip K1 and the sensor K2 meet each other as a result and the sensor K2 reads the information available on the RFID chip K1. The sensor K2 is thus used as a monitoring device which records when the sensor K2 and the RFID chip K1 are opposing each other.

(17) The trigger position A, i.e. the position in which the marking of the belt (RFID chip K1) and the marking of the disc (sensor K2) are directly opposing each other and the sensor K2 emits a corresponding signal X, is defined as the position in which the sensor K2 and the RFID chip K1 with the tooth Z of the belt R equipped with the RFID chip K1 sitting in the gap C both sit on the straight line G, said straight line runs through the rotational axes D1, D2 of the discs U, M (09:00 position of disc U). The RFID chip K1 and the sensor K2 are thus just before the trigger position A in FIG. 3 in the case of the rotational direction indicated for the drive disc M.

(18) The sensor K2 delivers the signal X, which indicates that the RFID chip K1 and the sensor K2 have reached the trigger position A at the same time, as a radio signal to a transceiver device W which sends the signal X to a receiver device N for example via WLAN or LAN which is in turn coupled to an evaluation device Y.

(19) In addition to the signal which indicates the meeting of the RFID chip K1 and the sensor K2 in the trigger position A, the signal X may also comprise information which the sensor K2 read out from the RFID chip K1.

(20) The evaluation device Y records the number of the signals X sent and associated therewith the number of circulations completed by the belt R. Based on this information and the additionally transmitted information read out by the RFID chip K1 regarding for example quality and state of the belt R, a prediction is made regarding its expected remaining service life and required maintenance measures initiated.

(21) Based on FIG. 4, it can be discerned that respectively one marking K1 can be arranged in the region of the teeth Z of the belt R particularly loaded in practical use wherein these markings K1, as previously explained, are usually an active sensor or an RFID element. The marking K1 can accordingly bear, record, send or collect information regarding the belt R in order to deliver it to the sensor K2 used as the monitoring device. In addition to the markings K1, a conventional storage device for storing electric energy may also be available in the region of the teeth Z of the belt R via which the active markings K1, i.e., the sensors or active identification means used as markings in the sense of the invention are supplied with the energy required for their operation.

(22) As shown in FIGS. 4 and 5, photovoltaic elements P1 for generating electric energy or light-emitting elements P2, for example photo diodes are arranged on the rear side of the belt R facing away from the teeth Z of the belt R, said photo diodes can emit light signals in order to signal certain operational states of the respective belt R. The connection between the elements P1 and the energy storage device or the marking K1 takes place via electrically conductive fibres F incorporated into the belt R which may be incorporated into the material of the belt R for example as part of the tensile member T or as a separate connection conductor.

(23) A photovoltaic element P3 for generating the energy which is required to operate the sensor K2 is arranged in a corresponding manner adjacent to the sensor K2 on the front end of the drive disc M.

(24) Lift drives should be mentioned as a further practical example for the teaching disclosed here in the case of which two toothed belts operating in parallel are generally operated for safety reasons. If one belt fails, then the remaining belt can still maintain the load or at least distribute it in a controlled manner.

(25) Lift drives often carry out only one movement between a lower and an upper end position between which, however further stops can be completed at defined positions if required. As a result of this, the same teeth of the belts are always loaded with the brake and accelerating forces. In this regard, it concerns teeth which are located in the looping region of the belt disc at the time of the respective stop or when the respective end position has been reached. The same belt tooth is also always in the same disc gap in the same stroke position.

(26) By providing the belts and the discs with a marking, in particular a marking formed as an identification means, the strokes achieved can be determined by the number of contacts in the respective positions. To this end, at suitable points, an RFID can for example be implemented in a belt tooth as a marking and a sensor likewise used as a marking can be implemented in a disc gap. The respective tooth is clearly characterised by the information borne by the RFID such that it can be clearly determined when the tooth reaches the respective gap in the critical stop position.

(27) The disc easily rolls over the other belt teeth without causing large loads on the respective teeth. The number of contacts carried out between the relevant teeth and the disc can thereby be determined for the critical teeth and the remaining service life can be reliably predicted up to a possible belt failure by comparison with the reachable contacts stored in a database.

(28) The ideal force distribution on both belts results when both belts are produced and pre-stressed in an identical manner. The force or the tensile load of the belts can be determined via strain gauges. The tensile load can be measured by means of suitable sensors and transmitted by means of suitable transmission means (for example by means of RFIDs) to an external receiver. This can take place on the discs or at any point on the belt.

(29) It is also conceivable for both belts or sensors on both belts to synchronise the respectively applied stress with each other. The tensile members present in the belt may be used for the purpose of energy conduction, transfer or input.

(30) In the reverse operation, not all sections of the belt run around the disc. At the regions, which do not run around the disc, a signal device implemented in the belt can for example indicate by way of an optical signal whether or not the belt is in an orderly state. This signal device can in particular indicate whether or not the loads present in the belt are within a predefined tolerance scope. If there is an excessively large deviation, this can also be signaled via the evaluation device coupled to the monitoring device such that the unit can be turned off prior to the occurrence of greater damage.

REFERENCE NUMERAL

(31) A Trigger position C Gap between the teeth Zs1, Zs2 D1, D2 Rotational axes of the discs U, M E Drive unit F electrically conductive fibres G Straight line K1 RFID chip K2 Sensor (marking and monitoring device) L Linear drive unit M Drive disc MZ Centre of a tooth Z N Receiver device P1 Photovoltaic element P2 Light-emitting element P3 Photovoltaic element Q Omega drive R Belt S Slide T Tensile member of the belt R U Deflection discs W Transceiver device X Signal Y Evaluation device Z Teeth of the belt R Zs1, Zs2 Teeth of the disc U