METHOD FOR MONITORING THE OPERATION OF A TRANSMISSION SYSTEM EQUIPPED WITH PULLEYS AND A TRANSMISSION BELT

Abstract

A method for monitoring the operation of a transmission system (1) comprising a belt (10) mounted on drive pulleys (R) and driven pulleys (N) of given radii, the method comprising the following steps: determining a rotational speed of the pulleys; determining a driven torque for the driven pulley; determining tensions exerted on slack (11) and tension (12) strands of said belt; determining a slip angle of said belt on one of said pulleys from step c); calculating an energy efficiency of said system from steps a) and b); calculating an abrasion rate of said belt from said given radii and steps c) and d); comparing the values ​​calculated in steps e) and f) respectively to given threshold values; and generating a warning when one of said threshold values ​​is exceeded. Figure for the abstract: Fig. 1

Description

Title of the invention: METHOD FOR MONITORING THE OPERATION OF A TRANSMISSION SYSTEM EQUIPPED WITH PULLEYS AND A DRIVE BELT Technical field of the invention

[0001] The present invention relates to a method for monitoring the operation of a transmission system equipped with pulleys and a drive belt, in particular transmission systems used in the field of industrial machinery. Technological background

[0002] Transmission systems are commonly used in various fields and industrial sectors to transmit mechanical energy from a power source to a tool or accessory. Among these transmission systems, belt systems can be distinguished, which include pulleys on which the transmission belt is mounted. The transmission belt is driven by a drive pulley and subsequently drives a driven pulley, which is generally connected to a tool or accessory via a drive shaft.

[0003] In such transmission systems, it is important to be able to monitor the evolution of given parameters to ensure the proper functioning of the transmission system.

[0004] These parameters may, for example, relate to the belt or pulleys, in particular the respective rotational speeds used to determine the slip rate of the transmission belt on the pulleys. Other parameters may also relate to the aging of the transmission belt, focusing, for example, on cracking of the belt teeth, pull-out of the belt cables, or shear stresses on the teeth.

[0005] However, when such approaches are considered, they do not take into account the overall performance of the transmission system in terms of belt abrasion and energy efficiency.

[0006] Indeed, monitoring the abrasion level of a transmission belt in an industrial application generally requires shutting down the installation to remove the belt and weigh it to determine its mass loss before reinstalling it. This procedure is complex, time-consuming, and expensive.

[0007] As for monitoring the system's energy efficiency, a complex protocol is generally implemented. This involves specific measuring devices, which are expensive due to their high precision and often complex to use, requiring advanced technical skills for optimal operation. Furthermore, The time required for these measures is significant and does not allow for a rapid response in the event of unfavorable performance.

[0008] Also, an objective of the invention is to propose an improved method for monitoring the operation of a belt transmission system which does not present at least one of the aforementioned disadvantages.

[0009] Another objective of the invention is to propose a solution providing a value of the level of abrasion and energy efficiency in real time using numerical models and simple algorithms.

[0010] Another objective of the invention is to propose a solution using easily quantifiable input quantities. Summary of the invention

[0011] A method for monitoring the operation of a transmission system comprising at least two pulleys of given radii Rr, Rn and a transmission belt mounted on the pulleys is therefore proposed, one of the at least two pulleys being a driving pulley and the other of the at least two pulleys being a driven pulley, the method comprising the following steps: a. determine a rotational speed coR, coN of each of the pulleys; b. determine a receiving torque CN for the receiving pulley; c. determine a tension t exerted on a slack strand of the belt transmission and a tension T exerted on a taut strand of the belt; d. determine a slip angle aG of the transmission belt on one of the pulleys from the data determined in step c); e. calculate an energy efficiency q of the transmission system from the data determined in steps a) and b); f. calculate an abrasion rate irab of the transmission belt from the radii of the pulleys and the data determined in steps c) and d); g. compare the calculated value of the abrasion rate irab to at least a first given threshold value and compare the calculated value of the energy efficiency q to at least a second given threshold value; and h. generate a warning when either of at least one first and at least one second threshold values ​​is exceeded.

[0012] Thus, thanks to the invention, the operation of the improved transmission system can be monitored by continuously tracking its performance. Generally, any belt mounted on pulleys wears out over time, whether through friction or a decrease in tension between the pulleys, and thus the performance of the transmission system decreases over time. The invention also makes it possible to detect abnormal changes in these performance levels.

[0013]

[0014]

[0015]

[0016]

[0017]

[0018]

[0019] Formances. Indeed, the input data, whether intrinsic to the transmission system such as geometric parameters like pulley radii or belt dimensions, or variables like pulley rotation speed, belt slack and tension tensions, or belt slip angle on a pulley, are easily accessible through calculation, measurement, or manufacturer specifications. This input data allows for the determination of belt abrasion level and the energy efficiency of the transmission system, which are important parameters for determining whether the transmission system is operating normally or not; in other words, whether or not maintenance of the transmission system is necessary, for example, by adjusting the system tension or replacing one of its components such as the belt or a pulley.More generally, this allows an operator to intervene quickly in case of malfunction and to plan the necessary maintenance. The method according to the invention may include one or more of the features below, taken individually or in combination with each other. In one embodiment of the invention, in step b), the receiving torque CN is calculated from the radius Rr, Rn of each of the driving and receiving pulleys, the rotational speeds coR, coN of each of the driving and receiving pulleys and a longitudinal module EA of the transmission belt. In another embodiment, when the drive pulley rotates clockwise, the received torque CN, being negative by convention, is defined by: _ OP PA In another embodiment, in step b), the receiving torque CN is measured using at least one torque sensor. In another embodiment, at step c), the tensions t, T exerted on the slack and tensioned strands of the transmission belt are calculated from the radius of the driven pulley, the driven torque CN, negative by convention, and a stabilized tension To of the transmission belt on the pulleys. In another embodiment, when the drive pulley (R) rotates according to a In the clockwise direction, the tension t exerted on the slack strand is defined by: + A a and the •HAS' The tension T exerted on the stretched strand is defined by: j1 _ t Cn ■ In another embodiment, the transmission system includes a tensioner installed on the slack side of the transmission belt to impose a tension t = To on the slack side. The tension T exerted on the tensioned side of the transmission belt is then calculated from the radius of the driven pulley and the torque. receiver CN, negative by convention, and the stabilized voltage To of the soft strand.

[0020] In another embodiment, when the drive pulley (R) rotates clockwise, the tension T exerted on the tensioned strand (12) is defined by: y = t Cn •

[0021] In another embodiment, in step c), the tensions t, T exerted on the slack and tensioned strands are measured by means of at least one tension sensor integrated into the transmission belt or by means of at least one tension sensor external to the transmission belt.

[0022] In another embodiment, at step d), the sliding angle aG is calculated by the relation: Ç L ; p being a known coefficient of dynamic friction of the drive belt on the pulleys.

[0023] In another embodiment, at step f), the abrasion rate irab is defined by the relation: _ ; m0 being an initial mass of the belt of '' ab mn transmission, mioss being a loss of mass of the transmission belt for a single revolution of the belt on the pulleys and Ncycie being the number of revolutions made by the belt during a given operating time of the transmission system.

[0024] In another embodiment, the transmission belt being a belt having at least one tooth extending longitudinally, the mass loss mioss is defined according to the relation: m • h being an abrasion height, nd being a number of teeth of the belt, hd being a height of the teeth, a being an angle formed by a vertex of a tooth, p being the density of the belt and L being the length of the belt.

[0025] In another embodiment, the abrasion height ha is defined by the relation: / ^ =.kd 10 6 — —__lr ; kR being the Archard coefficient, dG a RG' being a slip distance of the transmission belt on a given pulley and p being a coefficient of dynamic friction of the belt on the pulleys and R; being the radius Rr of the driving pulley or the radius RN of the driven pulley, the given pulley being one of at least two pulleys.

[0026] In another embodiment, the transmission belt being a flat belt, the mass loss mioss is defined according to the relation: = h(,.pLB ; ha being a abrasion height, where p is the density of the belt, L is the length of the belt and B is the width of the flat belt.

[0027] In another embodiment, the abrasion height ha is defined by the relation: h — b P i J. -J- z ; kR being the Archard coefficient, dG being a the slip distance of the drive belt on a given pulley, where p is the dynamic friction coefficient of the belt on the pulleys, and B is the width of the flat belt and R; being the radius Rr of the driving pulley or the radius RN of the driven pulley, the given pulley being one of at least two pulleys.

[0028] In another embodiment, the slip distance dG of the transmission belt is calculated, for a given pulley, from the radius of the pulley and the slip angle aG of the transmission belt on the pulley, so that the slip distance dG is defined by the relation: dG = Rj-ac-

[0029] In another embodiment, the transmission belt being a belt with teeth extending longitudinally, for each of the pulleys, a shear stress per tooth oR d, oN d of the transmission belt is calculated from the radius Rr, Rn of a given pulley, the tension t, T exerted on each of the slack and tensioned strands of the transmission belt, a winding angle [3R, |3N of the transmission belt on the given pulley and a number of teeth nd of the belt.

[0030] In another embodiment, the shear stress oN d of the belt on the driven pulley is defined by the relation: _ 1 ; and the stress of ~ R .jp 'Pd shear per tooth oRd of the transmission belt on the drive pulley is defined by the relation: _ _ (221 1 . °Rd~ -~r^~

[0031] In another embodiment, the calculated value of the shear stress per tooth oR d, oNd is compared to at least one predetermined threshold value, so that an alert is generated when the calculated value of the shear stress per tooth is greater than at least one predetermined threshold value.

[0032] In another embodiment, in step e), the energy efficiency q is calculated from the radius RN, Rr of each of the pulleys, the rotational speed coR, coN of the pulleys and the receiving torque CN, so that the energy efficiency q is defined by: „ _ . r^r

[0033] In another embodiment, the transmission system comprising an electrical power sensor, the energy efficiency q is calculated, in step e), from an electrical consumption Peiec of the drive pulley, measured by said electrical power sensor, an electromechanical efficiency peiec_motor of an electric motor rotating said drive pulley, the rotational speed coN of the driven pulley and the driven torque CN, so that the energy efficiency q is defined by: _ IÇv-^vl 7 ~ np .

[0034] In another embodiment, for each of said pulleys, a sliding speed Vsiip R, Vsiip N of the transmission belt is distributed between said pulleys, said sliding speed Vsiip R, Vsiip N being calculated from the radius of each of the pulleys and the rotational speed coR, coN of each of the pulleys, so that the slip speed Vsiip N of the belt on the driven pulley is defined by the relationship: v >. — RxMirRNMN VshpN~ 2 and the slip speed Vsiip R of the belt on the The drive pulley is defined by the relation: y R — -

[0035] The invention is part of a sustainable development approach by enabling in particular, better control of the energy efficiency of a transmission system. Brief description of the figures

[0036] The invention will be better understood with the aid of the following description, given solely by way of example and made with reference to the accompanying drawings in which:

[0037] Figure 1 represents a schematic view of a transmission system equipped with pulleys and a transmission belt,

[0038] Figure [Fig. 2] represents a schematic view of the transmission system of Figure [Fig. 1] in which a tensioner is used,

[0039] Fig. 3 represents a schematic view of an example of a transmission belt, in particular a ribbed V-belt, used in the transmission system of Fig. 1 or Fig. 2.

[0040] Figure 4 represents a block diagram of the method for monitoring the operation of a transmission system, according to the invention. Detailed description of the invention

[0041] Fig. 1 represents a transmission system 1 comprising at least two pulleys R, N of given radii Rr, Rn and a transmission belt 10 mounted on the pulleys R, N. One of the pulleys is a drive pulley R and another of the pulleys is a driven pulley N (for the Anglo-Saxon terms "driveR" for motor and "driveN" for driven).

[0042] The transmission belt 10 being mounted between at least these two pulleys R, N, it comprises a slack strand 11 and a tension strand 12.

[0043] It is understood that the drive pulley R is the pulley that is rotated to drive the transmission belt 10 via a driving torque CR, and the driven pulley N is the pulley that is driven by the transmission belt 10 and is subjected to a driven torque CN. Furthermore, the drive pulley R rotates with a rotational speed coR and the driven pulley N rotates with a rotational speed coN.

[0044] In what follows, it is assumed that the drive pulley R rotates clockwise (arrow CW) and that the angles and torques are positive in this clockwise direction. In such a configuration, the tensioned strand 12 is located below the drive pulley R and the slack strand 11 is located above the drive pulley R.

[0045] In other words, the receiving torque CN of the driven pulley will be considered negative when power is taken from the transmission, thus braking the driven pulley receiver N. Consequently, the motor torque CR is positive.

[0046] In a configuration where the position of the slack strand 11 and the tensioned strand 12 is reversed compared to the configuration described above, it is understood that the receiving torque CN is positive and that the driving torque CR is negative. This configuration is not described below.

[0047] With reference to [Fig. 2], the transmission system 1 may include a tensioner 20. This tensioner 20 is configured to be installed on the slack strand 11 of the transmission belt 10 in order to impose a quasi-constant tension on the slack strand 11 of the belt. This tension is generally considered to be equal to the stabilized tension To of the belt 10. The stabilized tension To is the tension that exists in the belt when the transmission system is not transmitting any torque.

[0048] In what follows, it will be specified whether the tensioner 20 is considered to follow the operation of the transmission system 1. In the absence of an indication, it should be understood that the tensioner 20 is not considered or that its presence has no impact, or a negligible impact, on the parameters mentioned.

[0049] The transmission belt 10 has various intrinsic parameters. These parameters can be the length L of the belt, the width B of the belt, the density p of the belt, the initial mass m0 of the belt or the height H of the belt.

[0050] The transmission belt 10 may be an elastomer-based belt. The belt 10 may be a multi-ribbed belt, such as a poly-V® type, a V-belt, or a flat belt. The belt 10 may include traction cables 16 embedded within the belt 10, these traction cables extending longitudinally within the belt 10.

[0051] Furthermore, for a given transmission belt 10, whether or not it includes tension cables 16, a longitudinal modulus EA, specific to the belt, can be determined. This longitudinal modulus EA is homogeneous with Young's modulus and the cross-section of the tension cables 16 or the belt 10. In practice, this longitudinal modulus EA is determined on a test bench.

[0052] The transmission belt 10 may comprise a plurality of teeth 15 extending longitudinally to the belt 10. In such a case, additional parameters may be considered to define the belt 10. For example, the number of teeth nd, the height of the teeth hd or the angle a formed by the apex 17 of each of the teeth 15 may be considered.

[0053] For example, in the case of a poly-V ® type belt, the angle of the apex 17 of the teeth 15 is substantially equal to 40 degrees.

[0054] Figure 4 shows a block diagram of a method 100 for monitoring operation of a transmission system 1 as described above, that is to say with at less two pulleys R, N and a transmission belt 10 mounted on these pulleys R, N. It is understood that the number of driven pulleys N is not limited.

[0055] The process 100 comprises the steps described below. It should be noted that the different steps are not necessarily carried out in the order presented below.

[0056] At a step a), or step 102, a rotational speed coR, coN of each of the pulleys R, N is determined.

[0057] In step b), or step 104, a receiving torque CN for the driven pulley N is determined. Step 104 can be carried out before, after, or simultaneously with step 102.

[0058] In a step c), or step 106, a tension t applied to a slack strand 11 of the transmission belt 10 and a tension T applied to a taut strand 12 of the belt 10 are determined. Step 106 may be carried out before, after, or simultaneously with either of steps 102 and 104.

[0059] At a step d), or step 108, a slip angle aG of the transmission belt 10 on one of the pulleys R, N is determined from the data determined at step c), or step 106.

[0060] At a step e), or step 110, an energy efficiency q of the transmission system 1 is calculated from the data determined in steps a) and b), i.e. in steps 102 and 104. Step 110 can be carried out before, after or simultaneously with steps 106 and 108 but after steps 102 and 104.

[0061] At a step f), or step 112, an abrasion rate irab of the transmission belt 10 is calculated from the radii Rr, Rn of the pulleys and the data determined in steps c) and d), i.e. in steps 106 and 108. Step 112 can be carried out before, after or simultaneously with step 110 but after steps 106 and 108.

[0062] At a step g), or step 114, the calculated value of the abrasion rate irab is compared to at least a first given threshold value and the calculated value of the energy efficiency q is compared to at least a second given threshold value.

[0063] At step h), or step 116, a warning is generated when either of the calculated values ​​of the abrasion rate irab and energy efficiency q is respectively higher or lower than the first and second threshold values. This warning may be an audible or visual alert. In particular, this warning may be the communication of a text alert via a computer system or network. The warning informs an operator of the system's status, whether its operation can be considered normal or not.

[0064] In step 114, the abrasion rate irab can be compared, in addition to the first threshold value SI, to a third threshold value S3 so as to define three ranges of values ​​Gl, G2, G3. The third threshold value S3 can be lower or higher than the first threshold value SL. For example, a first range of values ​​Gl includes values ​​that are greater than or equal to the first threshold value SI, so that SI < Gl. A second range of values ​​G2 includes values ​​that are lower than the first threshold value SI but greater than or equal to the third threshold value S3, such that S3 < G2 < SI. Finally, a third range of values ​​G3 includes values ​​that are lower than the third threshold value S3, such that G3 < S3. Thus, in step 116, a specific warning can be generated when the calculated value of the abrasion rate irab falls within one of the ranges of values ​​Gl, G2, or G3.

[0065] The same can be applied to the energy efficiency q. That is, in step 114, the energy efficiency q can be compared, in addition to the second threshold value S2, to a fourth threshold value S4 so as to define three ranges of values ​​PI, P2, and P3. The fourth threshold value S4 can be lower or higher than the second threshold value S2.For example, a first range of values, P1, includes values ​​that are greater than or equal to the second threshold value, S2, such that S2 < P1. A second range of values, P2, includes values ​​that are less than the second threshold value, S2, but greater than or equal to the fourth threshold value, S4, such that S4 < P2 < S2. Finally, a third range of values, P3, includes values ​​that are less than the fourth threshold value, S4, such that P3 < S4. Thus, in step 116, a specific warning can be generated when the calculated value of the energy efficiency q falls within one of the ranges of values: P1, P2, or P3.

[0066] Having several ranges or sets of values ​​allows the warning to be presented at several levels. These levels can, for example, depend on the severity of the system's malfunction.

[0067] In step 102, the rotational speed coR, coN of each of the pulleys R, N can be measured by means of at least one speed sensor. It is understood that for each pulley R, N at least one speed sensor measures the rotational speed coR, coN. The rotational speed coR of the drive pulley R can be an input parameter of the transmission system 1, given, for example, by a control device of the transmission system 1.

[0068] In step 104, the received torque CN can be calculated from the radius Rr, Rn of each of the drive pulleys R and driven pulleys N, the rotational speeds coR, coN of each of the drive pulleys R and driven pulleys N and the longitudinal module EA of the transmission belt 10, so that, when the drive pulley R rotates in a clockwise direction, the received torque CN is defined by:

[0069] [Math.l] f — p P pA

[0070] In step 104, the CN receiver torque can, alternatively, be measured using at least one torque sensor.

[0071] In step 106, the tensions t, T exerted on the slack 11 and taut 12 strands of the The tenths of a transmission belt can be measured using at least one tension sensor. This tension sensor can be integrated into the belt, for example with a strain gauge or a pressure sensor, or external to the belt, for example with an instrumented roller located at a tensioner.

[0072] In step 106, alternatively, the tensions t, T exerted on the slack 11 and tension 12 strands of the transmission belt 10 can be calculated, when there is no tensioner 20, from the radius of the driven pulley RN, the driven torque CN, negative by convention, and a stabilized tension To of the transmission belt on the pulleys R, N, so that, when the drive pulley R rotates clockwise, the tension t exerted on the slack strand 11 is defined by:

[0073] [Math.2]

[0074] and the tension T exerted on the tensioned strand 12 is defined by:

[0075] [Math.3] N

[0076] The tension t of the slack strand 11, the tension T of the tensioned strand 12 and the stabilized tension T0 of the belt 10 are expressed in Newtons.

[0077] We now consider the embodiment in which the transmission system 1 includes a tensioner 20 installed on the slack strand 11 of the transmission belt 10 to impose a quasi-constant tension t = To on the slack strand 11. For this embodiment, in step 106, the tension T exerted on the tensioned strand 12 of the transmission belt 10 can be calculated from the driven torque CN, the radius of the driven pulley RN, and the stabilized tension To of the slack strand 11, such that, when the drive pulley R rotates clockwise, the tension T exerted on the tensioned strand 12 is defined by:

[0078] [Math.4] r= ÿ,

[0079] It will be noted that the tensioner 20 in the transmission system 1 influences the calculation of the tension t, T for each of the slack 11 or tensioned 12 strands of the belt 10. Also, in calculations involving tension, the tension t, T calculated with tensioner 20 is used when the transmission system 1 includes a tensioner 20.

[0080] In step 108, the sliding angle aG is calculated using the following relation:

[0081] [Math.5]

[0082] where p is a known dynamic friction coefficient of the transmission belt 10 on the pulleys R, N. Classically, the dynamic friction coefficient of the belt is determined using a test bench that simulates a transmission system

[0083] The sliding angle aG is expressed in radians (rad).

[0084] Generally, the coefficient of friction p and the tensions t, T of the slack 11 and tension 12 strands of the belt 10 are identical whether on the drive pulley R or the driven pulley N. Therefore, the slip angle aG on each pulley R, N is the same. It is understood that the slip angle aG is always, regardless of the pulley considered, on the outward side of the belt 10. In other words, on the drive pulley R, the slip angle aG is on the side of the slack strand 11, while on the driven pulley N, the slip angle aG is on the side of the tension strand 12.

[0085] It will be noted that, for a given pulley R, N, the sliding angle aG cannot be greater than a winding angle [3 of the belt 10 on the pulley R, N considered, nor be less than 0. The winding angle [3, like the sliding angle aG, is expressed in radians.

[0086] Furthermore, for each pulley R, N, a slip zone %G can be determined. This slip zone %G corresponds to the portion of the wrap angle [3] over which the belt 10 slides and can be defined as a ratio between the slip angle aG and the wrap angle [3], according to the relation:

[0087] [Math.6] % — / 0G~ P

[0088] The slip zone %G indicates the proportion of the belt's wrap around the pulley by which the belt slips. Therefore, when the slip zone %G value exceeds a predetermined threshold, an alert can be generated. For example, a first predetermined threshold could be 50% and a second predetermined threshold could be 80%, thus defining a first range of values ​​below 50%, a second range of values ​​between 50% and 80%, and a third range of values ​​above 80%. A specific alert can then be generated for each range of values.

[0089] Furthermore, for a given pulley R, N, a slip distance dG of the transmission belt can be calculated from the radius Rr, Rn of the pulley in question and the slip angle of the transmission belt on this pulley such that the slip distance dG is defined by the relation:

[0090] [Math.7] ^G ~

[0091] where R; is the radius Rr of the driving pulley R or the radius RN of the receiving pulley N.

[0092] We are now interested in calculating the energy efficiency q of the system of Transmission 1 of step 110. In general, efficiency is defined energy q being the ratio between the output power PN received by the driven pulley N and the input power PR supplied by the driven pulley R, which translates according to the relation:

[0093] [Math. 8]

[0094] The input power PR and output power PN are expressed in watts (W), but for convenience they will be expressed in kilowatts (kW). Although the torque CN exerted on the driven pulley N is negative, these two powers PR and PN are positive.

[0095] Furthermore, when the output power PN received by the driven pulley N is not measured directly, it can be calculated. Therefore, regardless of the type of configuration of the transmission system 1, the output power PN received by the driven pulley N can be calculated according to the following relationship:

[0096] [Math.9]

[0097] In some cases, the input power PR is neither known nor measured. In such a situation, an approximate energy efficiency qapp can be calculated from the radii Rr, Rn of the pulleys and the rotational speeds coR, coN of the pulleys, so that this efficiency q is defined by:

[0098] [Math. 10] _ ^app “ RrMr

[0099] This allows for a simple estimation of energy efficiency. This information is not intended to be precise but to indicate an order of magnitude when the input power PR and output power PN are unknown.

[0100] In other cases, the transmission system 1 may include an electrical power sensor configured to measure an electrical consumption PeieC, defined as the product of the electrical voltage and current. From this electrical consumption PeieC, the input power PR supplied by the drive pulley R can be measured according to the following relationship:

[0101] [Math. 11] — Pelec_motor^elec

[0102] where peiec_motor is the electromechanical efficiency of an electric motor rotating the drive pulley R. The electromechanical efficiency peiec_motor of the electric motor is a known parameter, generally given by the motor manufacturer and which can depend on a number of other parameters such as the temperature or the speed of the drive pulley R.

[0103] Also, when the transmission system 1 includes a power sensor In electrical operation, the energy efficiency q can be calculated, in step 110, from the electrical consumption Peiec of the drive pulley R, measured by the electrical power sensor, the electromechanical efficiency peiec_motor of an electric motor rotating the drive pulley R, the rotational speed coN of the driven pulley N, determined in step 102, and the driven torque CN, determined in step 104, so that the energy efficiency q is defined by:

[0104] [Math. 12] — n P , “elec_motor mï

[0105] When the transmission system 1 includes an electrical power sensor, the calculation of energy efficiency is more accurate than in the previously described case where the input power is not known.

[0106] In other cases, the transmission system 1 may include a torque sensor on the drive pulley R or the pulley N configured to measure the motor torque CR of the drive pulley R or the torque CN of the pulley N. From this motor torque CR and the rotational speed coR of the drive pulley R, the input power PR supplied by the drive pulley R can be calculated according to the following relationship:

[0107] [Math. 13] PR ~

[0108] Similarly, from this receiving torque CN and the rotational speed coN of the receiving pulley N, the output power PN exerted on the receiving pulley N can be calculated according to the relation:

[0109] [Math. 14] .P= Cjy.tÜY

[0110] Also, when the transmission system 1 includes a torque sensor on the drive pulley R or on the driven pulley N, in step 110, the energy efficiency q can be calculated from the rotational speed coR, coN of the pulleys R, N, determined in step 102, the drive torque CR and the driven torque CN, determined in step 104, so that the energy efficiency q is defined by: [YES] [Math. 15] C, v. Wy

[0112] Energy losses Pioss can be defined as the difference between the input power PR supplied by the driving pulley R and the output power PN received by the driven pulley N. This translates into the following relationship:

[0113] [Math. 16] Ploss — Pr~ PN

[0114] From the energy loss Pioss, an economic loss C can be calculated on a period of time given by the relationship:

[0115] [Math. 17] C = Plos.^lkW^y

[0116] where Cikwh represents the cost of one kilowatt-hour in monetary units and ty is the time expressed in hours. The economic loss C is expressed in monetary units for the duration ty.

[0117] Thus, at the end of step 110, the user can have an indication of the energy efficiency or energy losses, or even economic losses, generated by the transmission system 1.

[0118] We are now interested in calculating the abrasion rate irab of the belt 10 of the transmission system 1 in step 112. Step 112 can be carried out simultaneously, before or after step 110.

[0119] In step 112, the abrasion rate irab is calculated as the ratio between the total mass loss mioss tot and the initial mass m0 of the belt 10 according to the relation:

[0120] [Math. 18] ^ab— mè)

[0121] The total mass loss mioss tot is the product of the mass loss mioss of the belt 10 for a single belt revolution 10 and the number of revolutions Ncycie made by the belt 10 during the operating time tF of the transmission system 1. The abrasion rate irab can therefore be defined according to the relationship:

[0122] [Math. 19] ^ab— «A;

[0123] Thus, for a given pulley R, N, a mass loss mioss of the transmission belt 10 can be defined, when the belt 10 is provided with at least one tooth 15 extending longitudinally, according to the relation:

[0124] [Math.20]

[0125] where ha is an abrasion height, p is the density of the belt 10, L is the length of the belt 10, nd is the number of teeth 15, hd is the height of these teeth 15 and a is the angle of the apex 17 of tooth 15.

[0126] When the belt 10 is flat, in other words when it does not have teeth 15, the mass loss mioss of the transmission belt 10 can be defined according to the relation:

[0127] [Math.21] mioss — ha.pLB

[0128] where B is the total width of the belt 10 which is flat.

[0129] The number of Ncycie turns is given in particular by the relation:

[0130] [Math.22] AT __ 'F-RR1''R cycle ~ --7--

[0131] The density p, the length L, the width B, the number nd of teeth 15, the height hd of these teeth 15 and the angle a of their apex 17 are intrinsic parameters of the transmission belt 10 and are known beforehand.

[0132] The abrasion height ha, or abraded height, of the belt 10 can be calculated from the following relationship:

[0133] [Math.23] ha — k^P .dG

[0134] where kR is the Archard coefficient which depends on intrinsic characteristics of the belt and the temperature and which is expressed in mmVN.m (cubic millimeter per Newton meter), P is the average contact pressure of the transmission belt 10 on a given pulley which is expressed in MPa (megapascal), and dG the slip distance expressed in meters and already defined previously; the given pulley being one of at least two pulleys R, N.

[0135] It should be noted that the abrasion height ha is calculated here for a single belt rotation.

[0136] The Archard coefficient kR is an empirical coefficient that is known for a given belt. This coefficient also generally depends on the temperature.

[0137] The average contact pressure P of the transmission belt 10 on the pulley R, N will depend on the type of belt installed.

[0138] For example, when the transmission belt 10 installed on the pulleys R, N of the transmission system 1 is a belt with longitudinal teeth 15, such as a poly-V® type belt, the average contact pressure P on the sliding arc on a given pulley can be calculated from the sliding angle, the tensions exerted on the slack 11 and tension 12 strands of the belt 10 and the radius of the given pulley, so that the average contact pressure P is defined by the relation:

[0139] [Math.24] P = 1 (f6- -1--—---- -«G

[0140] where nd is a number of teeth 15 of the belt 10, hd is the height of the teeth 15, a is the angle formed by the apex 17 of the teeth 15, p is the coefficient of friction of the belt 10 on the pulley considered and R; is the radius Rr of the driving pulley R or the radius RN of the driven pulley N.

[0141] When the transmission belt 10 installed on the pulleys R, N of the transmission system 1 is a flat belt, i.e. without teeth, the contact pressure The average P over the sliding arc on a given pulley can be calculated from the sliding angle, the tensions exerted on the slack 11 and tension 12 strands of the belt 10 and the radius of the given pulley, so that the average contact pressure P is defined by the relation:

[0142] [Math.25] p _ i n-6 1 1 Tt

[0143] where B is the width of the flat belt and R is the radius Rr of the drive pulley R or the radius RN of the driven pulley N.

[0144] Optionally, a slip velocity Vsiip_R, Vsiip_N of the transmission belt 10 can be calculated for each of the pulleys R, N. The slip velocity Vsiip_R, Vsiip_N represents a relative tangential velocity between the belt 10 and the pulley R, N under consideration. This slip velocity Vsiip_R, Vsiip_N can be calculated from the radius Rr, Rn of each of the pulleys R, N and the rotational speed coR, coN of each of the pulleys R, N, determined in step 102, so that the slip velocity Vsiip_N of the belt 10 on the driven pulley N is defined by the relation:

[0145] [Math.26] \7 _ ~ 2

[0146] and such that the slip speed Vsiip_R of the belt 10 on the drive pulley R is defined by the relation:

[0147] [Math.27] TT _ Pr-^'R^N^'N slip^R 2

[0148] The slip speed Vsiip_R on the drive pulley R is negative because the belt 10 rotates more slowly than the drive pulley R, while on the driven pulley N, the belt 10 rotates more quickly than the driven pulley N due to the negative driven torque CN which will tend to brake the driven pulley N, which explains the slip and why the slip speed Vsiip N is positive.

[0149] In the above, the slip is distributed in an equivalent and arbitrary manner between driving pulley R and receiving pulley N.

[0150] Alternatively, the slippage can be entirely distributed over one of the two pulleys R, N. In other words, when the slippage is entirely distributed over the driven pulley N, the slippage speed Vsiip N of the belt 10 over the driven pulley N can be defined by the relation:

[0151] [Math.28] slipN — RrMr ~ Rn-P'n

[0152] and, when the slippage is fully distributed over the drive pulley R, the slippage speed Vsiip_R of the belt 10 over the drive pulley R can be defined by the relationship :

[0153] [Math.29] V slipR ~ " ^rwR "

[0154] The calculation of the sliding speed can be carried out before any of the steps 104 to 116 but after step 102.

[0155] Optionally, a slip ratio rsiip_R, rsiip_N of the drive belt 10 can also be calculated for each of the pulleys R, N. This slip ratio rsiip_R, tshp_n can be calculated from the radius Rr, Rn of each of the pulleys R, N and the rotational speed coR, coN of each of the pulleys R, N, determined in step 102, so that the slip ratio rsiiP_N of the belt 10 on the driven pulley N is defined by the relation:

[0156] [Math.30] Tslip_N ~

[0157] and such that the slip ratio rsiip_R of the belt 10 on the drive pulley R is defined by the relation:

[0158] [Math.31] _ _ fyafrlWfr Tslip_R ~ 2.Rrwr

[0159] As with the sliding speed, the sliding is distributed in the preceding in an equivalent and arbitrary manner between driving pulley R and receiving pulley N.

[0160] Alternatively, the slippage can be entirely distributed over one of the two pulleys R, N. In other words, when the slippage is entirely distributed over the driven pulley N, the slip rate rsiiP_N of the belt 10 over the driven pulley N can be defined by the relation:

[0161] [Math.32] Tslip_N ~

[0162] and, when the slippage is fully distributed over the drive pulley R, the slip rate rsiip_R of the belt 10 over the drive pulley R can be defined by the relation:

[0163] [Math.33] Tslip_R ~ Rrmr

[0164] The calculation of the slip rate can be carried out before any of the steps 106 to 116 but after step 104.

[0165] For each of the pulleys R, N, the slip rate rsiip_R, Tsiip_N can be compared to a predetermined threshold value. When the slip rate value rsiip_R, Tsiip_N is greater than the corresponding threshold value, an alert can be generated in a manner similar to that implemented in step 116.

[0166] It has also been observed that at a slip rate greater than 10%, the transmission belt 10 will tend to heat up, accelerating its degradation.

[0167] Optionally, for each of the pulleys R, N, a shear stress per tooth oRd, oNd of the transmission belt 10 can also be calculated, when the belt 10 has teeth 15. This shear stress per tooth oRd, oNd can be calculated from the radius Rr, Rn of each of the pulleys R, N, the tension t exerted on the slack strand 11, the tension T exerted on the tensioned strand 12, the tensions t, T being determined in step 104, and the wrap angle [3R] of the belt 10 on the driving pulley R or the wrap angle |3N] of the belt on the pulley N, as well as the number of teeth 15 of the belt 10, so that the shear stress oNd of the belt 10 on the driven pulley N is defined by the relation:

[0168] [Math.34] (Tf)! RN.pN-"d

[0169] and such that the shear stress oRd of the belt 10 on the drive pulley R is defined by the relation:

[0170] [Math.35]

[0171] The calculation of the shear stress per tooth oR d, oNd can be carried out before any of the steps 106 to 116 but after step 104.

[0172] When the shear stress per tooth oR d, oNd becomes too great, the tooth or teeth 15 of the belt shear and a tooth pull-out or cable pull-out phenomenon may occur.

[0173] For each of the pulleys R, N, the shear stress per tooth oR d, oN d can be compared to at least one predetermined threshold value. When the value of the shear stress per tooth oR d, oN d is greater than the corresponding threshold value, an alert can be generated in a manner similar to that implemented in step 116. It should be noted that the predetermined threshold values ​​for the shear stress per tooth oR d, oN d are dependent on the belt 10, in particular on the type of tooth profile 15 of the belt 10.

[0174] In general, it should be noted that all the calculations described above can be performed by a control unit. This control unit can, for example, be a computer system.

[0175] The method according to the invention is particularly suitable for a transmission system of a high-power industrial machine. This industrial machine may be, for example, a crusher, a grinder, a ventilation / air conditioning system. The process according to the invention is therefore of interest for industrial activities where shutdowns of an installation for breakdowns or maintenance are costly. For example, the transmission systems of a motor vehicle or similar equipment are not significantly affected by the process according to the invention.

[0176] In light of the foregoing, the method according to the invention ensures monitoring of the operation of the improved transmission system by continuously tracking its performance. Generally, any belt mounted on pulleys wears out over time, whether through a decrease in tension between the pulleys, which causes the belt to slip on a pulley and thus creates friction, or through excessive torque, which also causes slippage, thereby reducing the performance of the transmission system over time. The invention also makes it possible to detect abnormal changes in this performance. Indeed, the input data, such as the radii of the pulleys, their respective rotational speeds, the tensions of the slack and tension sections of the belt, and the angle of slippage of the belt on a pulley, are readily available through calculation, measurement, or information provided by the manufacturer.This input data makes it easy to determine the belt abrasion level and the energy efficiency of the transmission system, which are important parameters for determining whether the transmission system is in normal operation or not, in other words, whether or not it is necessary to plan maintenance of the transmission system by replacing one or more of its elements such as the belt or a pulley.

[0177] Another advantage of the method according to the invention is to provide a value of the level of abrasion and energy efficiency in real time using simple numerical models and algorithms.

Claims

Demands

1. A method (100) for monitoring the operation of a transmission system (1) comprising at least two pulleys (R, N) of given radii Rr, Rn and a transmission belt (10) mounted on said pulleys (R, N), one of said at least two pulleys being a driving pulley (R) and another of said at least two pulleys being a driven pulley (N), the method comprising the following steps: a. determine (102) a rotational speed coR, coN of each of the pulleys (R, N); b. determine (104) a receiving torque CN for the receiving pulley (N); c. determine (106) a tension t exerted on a slack strand (11) of the transmission belt and a tension T exerted on a taut strand (12) of said belt; d. determine (108) a sliding angle aG of said transmission belt on one of said pulleys from the data determined in step c); e. calculate (110) an energy efficiency q of the transmission system (1) from the data determined in steps a) and b); f. calculate (112) an abrasion rate irab of said transmission belt from the radii (Rr, Rn) of the pulleys and the data determined in steps c) and d); g. compare (114) the calculated value of the abrasion rate irab to at least a first given threshold value and compare the calculated value of the energy efficiency q to at least a second given threshold value; and h. generate (116) a warning when either of said at least one first and at least one second threshold values ​​is exceeded.

2. Method according to claim 1, wherein, in step b), the receiving torque CN is calculated from the radius Rr, Rn of each of the driving and receiving pulleys, the rotational speeds coR, coN of each of the driving (R) and receiving (N) pulleys and a longitudinal module EA of the transmission belt.

3. The method according to claim 2, wherein, when the drive pulley (R) rotates clockwise, the received torque CN, being negative by convention, is defined by: _ nnr' A CN~ -

4. Method according to claim 1, wherein, in step b), the receiving torque CN is measured by means of at least one torque sensor.

5. A method according to any one of claims 1 to 4, wherein, in step c), the tensions t, T exerted on the slack (11) and tension (12) strands of the transmission belt (10) are calculated from the radius of the driven pulley (RN), the driven torque CN, negative by convention, and a stabilized tension To of the transmission belt on said pulleys (R, N).

6. A method according to claim 5, wherein, when the drive pulley (R) rotates clockwise, the tension t exerted on the slack strand (11) is defined by: and the tension T exerted on the tensioned strand (12) is defined by: T — T - Cn 1 - 1 0

7. A method according to any one of claims 1 to 4, wherein the transmission system (1) includes a tensioner (20) installed on the slack strand (11) of the transmission belt (10) to impose a tension t = To on said slack strand (11), the tension T exerted on the tensioned strand (12) of the transmission belt (10) is then calculated from the radius of the driven pulley (RN), the driven torque CN, negative by convention, and the stabilized tension To of the slack strand.

8. A method according to claim 7, wherein, when the drive pulley (R) rotates clockwise, the tension T exerted on the tensioned strand (12) is defined by:

9. A method according to any one of claims 1 to 4, wherein, in step c), the tensions t, T exerted on the slack (11) and tension (12) strands are measured by means of at least one tension sensor integrated into said transmission belt (10) or by means of at least one tension sensor external to said transmission belt.

10. A method according to any one of claims 1 to 9, wherein, in step d), the sliding angle aG is calculated by the relation: aG = ±.ln(£) p being a known dynamic friction coefficient of the transmission belt on the pulleys (R, N).

11. A method according to any one of claims 1 to 10, wherein, at step f), the abrasion rate irab is defined by the relation: ah — m0 m0 being an initial mass of the transmission belt (10), mioss being a mass loss of the transmission belt for a single revolution of the belt over the pulleys and Ncycie being the number of revolutions made by the belt during a given operating time of the transmission system (1).

12. A method according to claim 11, wherein, the transmission belt being a belt having at least one tooth extending longitudinally, said mass loss mioss is defined according to the relation: 2hcrpUi .ai jm^= cos^)' ha being an abrasion height, nd being a number of teeth of the belt (10), hd being a height of said teeth, a being an angle formed by a vertex (17) of a tooth (15), p being the density of the belt and L being the length of the belt.

13. Method according to claim 12, wherein the abrasion height ha is defined by the relation: h — kd ]()-6lJ__Id____ t- « « \ 2 7 kR being the Archard coefficient, dG being a slip distance of the transmission belt on a given pulley and p being a coefficient of dynamic friction of the belt on the pulleys and R; being the radius Rr of the driving pulley (R) or the radius RN of the driven pulley (N), said given pulley being one of said at least two pulleys (R, N).

14. Method according to claim 11, wherein, the transmission belt being a flat belt, said mass loss mioss is defined according to the relation: mlo,s = ha.pJLB ha being an abrasion height, p being the density of the belt, L being the length of the belt and B being the width of the flat belt.

15. Method according to claim 14, wherein the abrasion height ha is defined by the relation: h» = hR.dG. 10 kR being the Archard coefficient, dG being a slip distance of the transmission belt on a given pulley, p being a coefficient of dynamic friction of the belt on the pulleys, B being the width of the flat belt and R; being the radius Rr of the driving pulley (R) or the radius RN of the driven pulley (N), said given pulley being one of said at least two pulleys (R, N).

16. A method according to any one of claims 13 or 15, wherein the slip distance dG of the drive belt (10) is calculated, for a given pulley, from the radius of said pulley and the slip angle aG of the drive belt on said pulley, such that the slip distance dG is defined by the relation: dG — Ri.aG

17. A method according to any one of claims 1 to 13, wherein, the transmission belt being a belt with teeth extending longitudinally, for each of said pulleys (R, N), a shear stress per tooth oR d, oN d of the transmission belt (10) is calculated from the radius Rr, Rn of a given pulley (R, N), the tension t, T exerted on each of the slack (11) and tension (12) strands of said transmission belt, a winding angle [3R, |3N] of said transmission belt on said given pulley and a number of teeth nd of the belt.

18. A method according to claim 17, wherein the shear stress oN d of the belt on the driven pulley (N) is defined by the relation: -1ZÏ1 J. aN_d ~ RN.pv'nd and the shear stress per tooth oRd of the drive belt on the drive pulley (R) is defined by the relation: (Tt) j ^R_d ~ ~

19. A method according to claim 18, wherein the calculated value of the shear stress per tooth oR d, oNd is compared to at least one predetermined threshold value, such that an alert is generated when said calculated value of the shear stress per tooth is greater than said at least a predetermined threshold value.

20. A method according to any one of claims 1 to 19, wherein, in step e), the energy efficiency q is calculated from the radius RN, RR of each of the pulleys, the rotational speed coR, coN of said pulleys (R, N) and the driven torque CN, such that the energy efficiency q is defined by:

21. A method according to any one of claims 1 to 19, wherein, the transmission system comprising an electrical power sensor, the energy efficiency q is calculated, in step e), from an electrical consumption Peiec of the drive pulley (R), measured by said electrical power sensor, an electromechanical efficiency peiec_motor of an electric motor rotating said drive pulley (R), the rotational speed coN of the driven pulley and the driven torque CN, such that the energy efficiency q is defined by: r eiec^motor W'1-

22. A method according to any one of claims 1 to 21, wherein, for each of said pulleys (R, N), a slip velocity Vsiip_R, Vsiip_N of the drive belt (10) is distributed between said pulleys, said slip velocity Vsiip_R, Vsiip_N being calculated from the radius of each pulley and the rotational speed coR, coN of each pulley, such that the slip velocity Vsiip_N of the belt on the driven pulley (N) is defined by the relation: TZ_1shpN - 2 and such that the slip velocity Vsiip_R of the drive belt (10) on the drive pulley (R) is defined by the relation: T7_1shpN - 2

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