DEVICE AND METHOD FOR ASCERTAINING A LONGITUDINAL EXTENSION AND THE AVERAGE SPEED OF A BELT AND FOR ASCERTAINING THE SPEED OF AT LEAST ONE BELT PULLEY

Abstract

The invention relates to a device for ascertaining a longitudinal extension and an average speed of a belt and for ascertaining a speed of at least one belt pulley, in which device at least one marking part pair is arranged respectively in the load strand and the idle strand over the circumference of the belt.

Claims

1. A device for ascertaining a longitudinal extension and an average speed (V2) of a belt and for ascertaining a speed (V3) of at least one belt pulley, comprising the belt of predetermined longitudinal stiffness, wherein the length of the belt is constant irrespective of the operating state, wherein the belt has at least a first marking part, a second marking part, a third marking part and a fourth marking part, wherein the first and the second marking part form a first marking part pair and the third and fourth marking part form a second marking part pair, a drive device having at least two belt pulleys of predetermined diameter which are arranged with an axis spacing from each other and around which the belt is at least partially looped, a transmission device comprising at least two external readers and an evaluation and control unit which is suitable for controlling the rotation speed and/or the torque of the drive device, wherein, as the belt revolves, signals (SM8, SM9, SM10, SM11) identifiable at the external readers can be generated by each marking part and can be output to the evaluation and control unit, wherein the belt is designed to revolve in a circumferential direction in the form of a ring and is driven by the drive device in the circumferential direction, wherein the belt has a load-transmitting load strand and an idle strand arranged opposite to the load strand, wherein, in a state without power transmission, the marking part, of the marking part pairs of the belt are each arranged one behind the other in the circumferential direction with a predetermined reference spacing (R), wherein the reference spacing of the marking parts of the first marking part pair is designed to change into a first measurement spacing when power is transmitted by the belt, wherein the reference spacing of the marking parts of the second marking part pair is designed to change into a second measurement spacing when power is transmitted by the belt, wherein at least one of the belt pulleys has at least one marking part, wherein, as the belt pulley rotates, the marking part of the belt pulley is designed to generate an identifiable signal at one of the external readers and output it to the evaluation and control unit, wherein the transmission device is arranged without contact with the belt in such a way that the marking parts of the marking part pairs of the belt and the belt pulley can be guided past the transmission device in succession, wherein the evaluation and control unit is configured to ascertain a respective running time from in each case two signals, wherein the evaluation and control unit is configured to ascertain an average speed of the belt based on the ascertained running time of one of the marking parts of the marking part pairs over the circumferential length over one revolution of the belt and a speed of the belt pulley based on the ascertained running time of the marking part of the belt pulley, wherein, in a state of the belt without power transmission, at least one marking part pair formed from the marking parts is arranged respectively in the load strand and the idle strand over the circumference of the belt, wherein the evaluation and control unit is configured to ascertain a longitudinal extension of the belt based on the average belt speed, the difference between the running times of the two consecutive marking parts of the marking part pairs of the belt both in the load strand and in the idle strand, and the measurement spacing ascertained therefrom of the marking parts of the marking part pairs from each other both in the load strand and in the idle strand, and the reference spacing as an average value from the ascertained measurement spacings to ascertain a tensile force and difference in tensile force in the load strand of the belt using the evaluation and control unit via a spring stiffness assigned to the belt and stored in the evaluation and control unit and a difference in spacing of the marking parts of the marking part pairs of the belt in the load strand, and is also configured to ascertain slip between the belt and the belt pulley based on the ratio of the average speeds ascertained from the belt and the belt pulley.

2. The device as claimed in claim 1, wherein the marking parts are designed as surface acoustic wave sensors.

3. The device as claimed in claim 1, characterized in that the marking parts are RFID transponders.

4. The device as claimed in claim 1, wherein the marking parts are ferromagnetic marking parts.

5. The device as claimed in claim 1, wherein the driven belt pulley has at least one marking part.

6. The device as claimed in claim 1, wherein one of the external readers is arranged in the region of the inlet and one in the region of the outlet of the belt into/out of the belt pulley.

7. The device as claimed in claim 1, wherein when predetermined limit values for slip between the belt and the belt pulley stored in the evaluation and control unit are exceeded, the evaluation and control unit is configured to control the drive torque or the drive speed in such a way that the slip moves to within defined limit values.

8. The device as claimed in claim 1, wherein the evaluation and control unit is coupled to further measuring devices of machine elements and comprises a memory for backing up historical sensor data and for backing up historical force profile data relating to the belt, wherein the evaluation and control unit is designed to monitor the historical force profile data relating to the belt within prespecified limit values stored in the memory of the evaluation and control unit, and, taking into account the historical sensor data relating to further machine elements from the memory of the evaluation and control unit, to draw a conclusion about the wear of machine elements outside the device.

9. The device of claim 1, further comprising an attachment to an agricultural machine.

10. A method for ascertaining a longitudinal extension (?) and an average speed (V2) of a belt and for ascertaining the speed (V3) of at least one belt pulley, comprising the belt with a predetermined longitudinal stiffness, wherein the length of the belt is constant irrespective of the operating state, wherein the belt has at least a first marking part, a second marking part, a third marking part and a fourth marking part, wherein the first and the second marking part form a first marking part pair and the third and fourth marking part form a second marking part pair, a drive device having at least two belt pulleys of predetermined diameter which are arranged with an axis spacing from each other and around which the belt is at least partially looped, a transmission device comprising at least two external readers and an evaluation and control unit which controls the rotation speed and/or the torque of the drive device, wherein, as the belt revolves, signals identifiable at the external readers are generated by each marking part and are output to the evaluation and control unit, wherein the belt revolves in a circumferential direction in the form of a ring and is driven by the drive device in the circumferential direction, wherein the belt has a load strand and an idle strand arranged opposite to the load strand, wherein, in a state without power transmission, the marking parts of the marking part pairs of the belt are each arranged one behind the other in the circumferential direction with a predetermined reference spacing in a non-loaded state of the belt, wherein the reference spacing of the marking parts of the first marking part pair changes into a first measurement spacing when power is transmitted by the belt, wherein the reference spacing of the marking parts of the second marking part pair changes into a second measurement spacing when power is transmitted by the belt, wherein at least one of the belt pulleys has at least one marking part, wherein, as the belt pulley rotates, the marking part of the belt pulley generates an identifiable signal at one of the external readers and outputs it to the evaluation and control unit, wherein the transmission device is arranged without contact with the belt in such a way that the marking parts of the marking part pairs of the belt and the belt pulley are guided past the transmission device in succession, wherein the evaluation and control unit ascertains a running time from in each case two signals, wherein the evaluation and control unit ascertains an average speed of the belt and the belt pulley from the running times, characterized by the following method steps: a) generating a signal from the first marking part of the belt at the first external reader, b) generating a signal from the second marking part of the belt at the first external reader, c) generating a signal from the third marking part of the belt at the first external reader, d) generating a signal from the fourth marking part of the belt at the first external reader, e) generating a signal from the first marking part of the belt at the second external reader, f) generating a signal from the second marking part of the belt at the second external reader, g) generating a signal from the third marking part of the belt at the second external reader, h) generating a signal from the fourth marking part of the belt at the second external reader, i) ascertaining a running time from in each case two signals using the evaluation and control unit, j) ascertaining the average speed of the belt using the evaluation and control unit based on the ascertained running time of one of the marking parts of the marking part pairs over the circumferential length over one revolution of the belt, k) ascertaining the difference between the running times of the two consecutive marking parts of the marking part pairs of the belt at the external reader assigned to the load strand using the evaluation and control unit, l) ascertaining the measurement spacing of the two consecutive marking parts of the marking part pairs in the load strand via the ascertained average speed of the belt and the ascertained difference between the running times of the two consecutive marking parts of the marking part pairs of the belt, m) ascertaining the difference between the running times of the two consecutive marking parts of the marking part pairs of the belt at the external reader assigned to the idle strand using the evaluation and control unit, n) ascertaining the measurement spacing of the two consecutive marking parts of the marking part pairs in the idle strand via the ascertained average speed of the belt and the ascertained difference between the running times of the two consecutive marking parts of the marking part pairs of the belt, o) ascertaining the difference in spacing of the two consecutive marking parts of the marking part pairs of the belt in the load strand and in the idle strand using the evaluation and control unit, p) ascertaining the reference spacing of the two consecutive marking parts of the marking part pairs of the belt using the evaluation and control unit via the ascertained measurement spacings of the two consecutive marking parts of the marking part pairs of the belt in the load strand and in the idle strand by averaging the measurement spacings q) ascertaining the longitudinal extension (?) in the load strand of the belt using the evaluation and control unit via the ascertained measurement spacing of the two consecutive marking parts of the marking part pairs of the belt in the load strand and the ascertained reference spacing, r) ascertaining the tensile force and difference in tensile force in the load strand of the belt using the evaluation and control unit via a spring stiffness assigned to the belt and stored in the evaluation and control unit and the difference in spacing of the two consecutive marking parts of the marking part pairs of the belt in the load strand, s) generating a signal from the marking part of the belt pulley at one of the external readers, t) ascertaining a running time of the marking part of the belt pulley from two signals using the evaluation and control unit, u) ascertaining the speed of the belt pulley using the evaluation and control unit based on the ascertained running time of the marking part of the belt pulley over the defined circumference of the belt pulley, v) ascertaining the slip between the belt and the belt pulley using the evaluation and control unit, based on the ascertained speeds of the belt and the belt pulley.

11. The method as claimed in claim 10, wherein when predetermined limit values for slip between the belt and the belt pulley stored in the evaluation and control unit are exceeded, the evaluation and control unit reduces the drive torque or the drive speed, so that the slip moves to within defined limit values.

12. The method of claim 10, wherein the evaluation and control unit stores and saves historical force profile data relating to the belt and further historical sensor data from measuring devices of further machine elements in a memory and monitors the historical force profile data relating to the belt within prespecified limit values stored in the memory of the evaluation and control unit, wherein, taking into account otherwise ascertained historical sensor data relating to further machine elements from the memory of the evaluation and control unit, a conclusion is drawn about the wear of machine elements outside the device.

13. The method of claim 19, further comprising monitoring belt-driven devices on attachments of an agricultural machine.

14. A device for ascertaining a belt longitudinal extension and an average belt speed, the device comprising a belt having a first marking part, a second marking part, a third marking part and a fourth marking part, the first and the second marking part form a first marking part pair and the third and fourth marking part form a second marking part pair, a drive device having at least two belt pulleys of predetermined diameter which are arranged with an axis spacing from each other and around which the belt is at least partially looped, a transmission device configured to generate marking signals for each marking part; a load transmitting strand of the belt and an idle strand of the belt; a control unit configured to: determine running times of the first marking pair and the second marking pair based on the marking signals; determine a longitudinal extension of the belt based on the running times of the first marking pair and the second marking pair; determine a tensile force of the load strand based on a spring stiffness assigned to the belt and spacings of the first marking pair and the second marking pair; determine a belt speed of the belt based on the marking signals; determine a pulley speed of the belt pulleys; and determine a slip between the belt and a belt pulley based on the belt speed and the pulley speed.

15. The device of claim 14, the belt is a toothed belt.

16. The device of claim 14, the marking parts are tags.

17. The device of claim 16, the marking parts comprise surface acoustic wave sensors (SAW) that can withstand vulcanization at temperatures of more than 200 degrees Celsius.

18. The device of claim 17, the marking parts receive energy from an external reader of the control unit.

19. The device of claim 18, the control unit further comprises a memory and stores historical force profile data of the belt in the memory.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0097] An exemplary embodiment of the invention will be explained in more detail below with reference to the drawing.

[0098] FIG. 1 shows a schematic view of an advantageous configuration of the device.

DETAILED DESCRIPTION

[0099] An advantageous configuration of the device 1 is schematically illustrated in FIG. 1. The device 1 comprises a belt 2 of predetermined longitudinal stiffness and a drive device 4 with, for example, two belt pulleys 3 of predetermined diameter which are arranged with an axis spacing A from each other. One of the two belt pulleys 3 is coupled as a driven belt pulley to a motor of the drive device 4. The belt 2 is designed to revolve in a circumferential direction U in the form of a ring and partially loops around each of the two belt pulleys 3. The belt 2 is driven by the drive device 4 with the two belt pulleys 3, so that the belt 2 revolves in the circumferential direction U.

[0100] The belt 2 has a base material and at least one reinforcement. For example, the base material may be partially or completely formed from rubber material, or partially or completely formed from polyurethane material. However, other materials for the base material may also be provided. The base material is preferably electrically insulating. The reinforcement is embedded in the base material as a continuous cord helically wound in the circumferential direction U. The reinforcement is used to transfer forces in the circumferential direction U of the belt 2. The reinforcement may be formed, for example, from a metal wire or from a plastic filament strand, such as a plastic fiber strand composed of polyamide for example. The individual turns of the cord forming the reinforcement in the transverse direction of the belt 2 can be arranged distributed in relation to each other. In this case, each of the turns extends in the circumferential direction U. The length of the belt 2 is constant irrespective of the operating state.

[0101] The belt 2 also has at least a first marking part 8, a second marking part 9, a third marking part 10 and a fourth marking part 11. In one embodiment, the marking parts 8, 9, 10, 11 are formed as SAW sensors and embedded into the base material of the belt. SAW sensors are particularly highly suitable for uses in a belt 2 since they withstand the required temperatures during production of the belt 2 and require only little energy for wireless data transmission of the sensor signals, and this allows them to be used at high relative speeds between the sensor and the associated external reader 6.1, 6.2. Here, the first marking part 8 and the second marking part 9 form a first marking part pair, while the third marking part 10 and the fourth marking part 11 form a second marking part pair. The first and the second marking part pair are arranged such that, in the idle state of the belt 2 without power transmission, one marking part pair is located in the load strand TR1 and one in the idle strand TR2. In the state of the belt 2 without power transmission, the marking parts 8, 9 and 10, 11 of the marking part pairs are each arranged one behind the other in the circumferential direction U with a predetermined reference spacing R. The reference spacing R changes into a first measurement spacing M1 of the marking parts 8, 9 of the first marking part pair and into a second measurement spacing M2 of the marking parts 10, 11 of the second marking part pair when power is transmitted by the belt 2.

[0102] Furthermore, one of the belt pulleys 3, which is preferably driven by a motor, also has a marking part 12 in the form of a SAW sensor.

[0103] A transmission device 5 comprises two external readers 6.1, 6.2 and an evaluation and control unit 7. One of the external readers 6.1, 6.2 is arranged in the region of the inlet and one in the region of the outlet of the belt 2 into and, respectively, out of the belt pulley 3 comprising the marking part 12. The transmission device 5 is arranged without contact with the belt 2 and the belt pulley 3, so that the marking parts 8, 9, 10, 11 of the marking part pairs of the belt 2 and the marking part 12 of the belt pulley 3 are guided past the transmission device 5 in succession. The marking parts 8, 9, 10, 11 of the marking part pairs of the belt 2 are detected by the external readers 6.1, 6.2 and identified on the basis of an individual identification of each individual marking part 8, 9, 10, 11 and output as a signal SM8, SM9, SM10, SM11 by the external readers 6.1, 6.2 to the evaluation and control unit 7.

[0104] Similarly, as the belt pulley 3 rotates, the marking part 12 is detected and identified by one of the external readers 6.1, 6.2 and output as a signal SM12 to the evaluation and control unit 7.

[0105] Here, each of the external readers 6.1, 6.2 is configured to capture the signals SM8, SM9, SM10, SM11, SM12.

[0106] The evaluation and control unit 7 is configured to ascertain a respective running time from in each case two signals SM8, SM9, SM10, SM11, SM12.

[0107] Furthermore, the evaluation and control unit 7 is configured to ascertain an average speed V2 of the belt 2 based on the ascertained running time TR of one of the marking parts 8, 9, 10, 11 of the marking part pairs over the circumferential length LR over one revolution of the belt 2 and a speed V3 of the belt pulley 3 based on the ascertained running time TS of the marking part 12 over the defined circumference LS of the belt pulley 3 stored in the evaluation and control unit 7.

[00001]$\begin{array}{c}V2=\frac{LR}{TR}\\ V3=\frac{LS}{TS}\end{array}$

[0108] By way of ascertaining the difference between the running times dTR of the two consecutive marking parts 8, 9 of the marking part pair in the load strand TR1 and the marking parts 10, 11 of the marking part pair in the idle strand TR2 of the belt 2, a first measurement spacing M1 of the marking parts 8, 9 of the first marking part pair and a second measurement spacing M2 of the marking parts 10, 11 of the second marking part pair can be ascertained together with the average belt speed V2. The difference between the running times dTR of the marking parts 8, 9 of the first marking part pair assigned to the load strand TR1 and the difference between the running times dTR of the marking parts 10, 11 of the second marking part pair assigned to the idle strand TR2 are ascertained respectively via the external reader 6.1 which is assigned to the load strand TRI and outputs the signals SM8, SM9 to the evaluation and control unit 7 and the external reader 6.2 which is assigned to the idle strand TR2 and outputs the signals SM10, SM11 to the evaluation and control unit 7.

M=V2*dTR

[0109] A difference in spacing dM of the two consecutive marking parts 8, 9 of the first marking part pair in the load strand TR1 and of the two consecutive marking parts 10, 11 of the second marking part pair in the idle strand TR2 from each other is ascertained from the ascertained measurement spacings M1 and M2 using the evaluation and control unit 7. The reference spacing R of the two consecutive marking parts 8, 9 of the first marking part pair in the load strand TR1 and the two consecutive marking parts 10, 11 of the second marking part pair in the idle strand TR2 is ascertained using the evaluation and control unit 7 by averaging the measurement spacings M1 and M2.

[00002]$\begin{array}{c}\mathrm{dM}=M1-M2\\ R=\frac{dM}{2}\end{array}$

[0110] In a next method step, the longitudinal extension ? of the belt 2 in the load strand TR1 is ascertained using the evaluation and control unit 7 based on the previously ascertained measurement spacing M1 and the reference spacing R.

?=M1?R

[0111] In a further method step, a tensile force Fz and a difference in tensile force dFz are ascertained using the evaluation and control unit 7.

[0112] Here, the difference in tensile force dFz corresponds to the force component which is added to the static pretensioning force by the drive power introduced into the belt drive via the drive belt pulley 3. For this purpose, a spring stiffness D individually assigned to the respective belt is stored in the evaluation and control unit 7. The spring stiffness D is dependent on the belt specification and has to be stored once in the evaluation and control unit 7 when setting up the machine. The information relating to spring stiffness can also be provided, for example, via a scannable barcode on the belt. Furthermore, the measurement spacing M1 should be used as the basis of the calculation for ascertaining the tensile force Fz and, respectively, the difference in spacing dM should be used as the basis of the calculation for ascertaining the difference in tensile force dFz.

Fz=D*M1

dFz=D*?

[0113] Furthermore, the evaluation and control unit 7 is intended to ascertain slip V4 between the belt 2 and the belt pulley 3, based on the ascertained speeds V2, V3 of the belt 2 and the belt pulley 3.

[00003]$V4=\frac{V3}{V2}-1$

LIST OF REFERENCE SIGNS

[0114] 1 Device [0115] 2 Belt [0116] 3 Belt pulley [0117] 4 Drive device [0118] 5 Transmission device [0119] 6.1 First external reader [0120] 6.2 Second external reader [0121] 7 Evaluation and control unit [0122] 8 First marking part of the belt [0123] 9 Second marking part of the belt [0124] 10 Third marking part of the belt [0125] 11 Fourth marking part of the belt [0126] 12 Marking part of the belt pulley [0127] A Axis spacing of the belt pulleys [0128] D Spring stiffness [0129] ? Longitudinal extension of the belt [0130] F Free strand length [0131] Fz Tensile force [0132] dFz Difference in tensile force [0133] L.sub.R Circumferential length of the belt [0134] L.sub.S Circumferential length of the belt pulley [0135] M1 Measurement spacing of the first marking part pair [0136] M2 Measurement spacing of the second marking part pair [0137] dM Difference in spacing [0138] R Reference spacing [0139] SM8 Signal from the reader of the first marking part of the belt [0140] SM9 Signal from the reader of the second marking part of the belt [0141] SM10 Signal from the reader of the third marking part of the belt [0142] SM11 Signal from the reader of the fourth marking part of the belt [0143] SM12 Signal from the reader of the marking part of the belt pulley [0144] TR Running time of a marking part of the belt over the circumferential length over one revolution of the belt [0145] dTR Difference between the running times of two consecutive marking parts of a marking part pair [0146] TS Running time of a marking part of the belt pulley over the circumferential length of the belt pulley [0147] TR1 Load strand [0148] TR2 Idle strand [0149] U Circumferential direction [0150] V2 Average belt speed [0151] V3 Speed of the belt pulley [0152] V4 Slip between the belt and the belt pulley