Method for monitoring the operation of a transmission system provided with pulleys and a transmission belt

Abstract

The invention relates to a method for monitoring the operation of a transmission system (1) comprising a belt (10) mounted on a driving pulley (R) and a driven pulley (N) of given radii, the method comprising the following steps: a) determining a rotational speed of the pulleys; b) determining a driven torque for the driven pulley; c) determining the tensions exerted on a slack strand (11) and a taut strand (12) of the belt; d) determining a slip angle of the belt on one of the pulleys on the basis of step c); e) calculating an energy efficiency of the system on the basis of steps a) and b); f) calculating a rate of wear of the belt on the basis of the given radii and steps c) and d); g) respectively comparing the values calculated in steps e) and f) with given threshold values; and h) generating a warning when one of the threshold values is exceeded.

Description

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

[0001] The present invention relates to a method for monitoring the operation of a transmission system provided with pulleys and a transmission 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. Within these transmission systems, we can distinguish belt systems that include pulleys on which the transmission belt is mounted. The transmission belt is driven by a drive pulley and subsequently drives a receiving pulley that is usually connected to a tool or accessory via a drive shaft.

[0003] In such transmission systems, it is interesting 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, concern the belt or the pulleys, in particular the respective rotational speeds which are used to determine a slip rate of the transmission belt on the pulleys. Other parameters may also concern the aging of the transmission belt by focusing, for example, on cracks in the belt teeth, tearing of the belt cords 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 on an industrial application generally requires shutting down the installation to disassemble the belt and weigh it to determine its mass loss before reassembling it on the installation. 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 accuracy and often complex to use, requiring advanced technical skills for optimal use. In addition, the time required for these measurements is significant and does not allow for 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 have at least one of the aforementioned drawbacks.

[0009] Another objective of the invention is to propose a solution providing a value of the abrasion level 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 is therefore proposed 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, one of the at least two pulleys being a driving pulley and another of the at least two pulleys being a receiving pulley, the method comprising the following steps: a) determining a rotation speed ωR, of each of the pulleys; b) determining a receiving torque CN for the receiving pulley; c) determining a tension t exerted on a slack strand of the transmission belt and a tension T exerted on a taut strand of the belt; d) determining a sliding angle αG of the transmission belt on one of the pulleys from the data determined in step c); e) calculating an energy efficiency η of the transmission system from the data determined in steps a) and b); f) calculate an abrasion rate π ab 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 π abto at least one first given threshold value and comparing the calculated value of the energy efficiency η to at least one second given threshold value; and h) generating a warning when either of the 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 is monitored by continuously monitoring the performance of the transmission system. Generally speaking, any belt mounted on pulleys wears over time, whether through friction or a reduction in its tension between the pulleys, and thus sees the performance of the transmission system decrease over time. The invention also makes it possible to detect an abnormal change in this performance. Indeed, the input data, whether intrinsic to the transmission system such as geometric parameters such as the radii of the pulleys or dimensions of the belt, or variables such as the rotation speed of the pulleys, the tensions of the slack and taut strands of the belt or the sliding angle of the belt on a pulley, are easily accessible by calculation, measurements or manufacturer's indication.These input data make it possible to determine a belt abrasion level and an energy efficiency of the transmission system which are important parameters to determine whether the transmission system is in normal operation or not, in other words whether it is necessary to plan maintenance or not of the transmission system by acting for example on the tension of the system or by replacing one or other of its elements such as the belt or a pulley. More generally, this allows an operator to intervene quickly in the event of a malfunction and to plan the necessary maintenance.

[0013] The method according to the invention may comprise one or more of the features below, taken in isolation from each other or in combination with each other.

[0014] 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 rotation speeds ωR, of each of the driving and receiving pulleys and a longitudinal module EA of the transmission belt.

[0015] In another embodiment, when the drive pulley rotates in a clockwise direction, the receiving torque C N , being negative by convention, is defined by:

[0016] In another embodiment, in step b), the receiving couple C N is measured by means of at least one torque sensor.

[0017] In another embodiment, in step c), the tensions t, T exerted on the slack and taut strands of the transmission belt are calculated from the radius of the receiving pulley, the receiving torque C N, negative by convention, and a stabilized tension T0 of the transmission belt on the pulleys.

[0018] In another embodiment, when the drive pulley (R) rotates in a clockwise direction, the tension t exerted on the slack strand is defined by: ^ = ^^ +^^; and the tension T exerted on the tight strand ^^^.^^ u is defined by: ^ = ^^ − ^.^^.

[0019] In another embodiment, the transmission system comprising a tensioner installed on the slack strand of the transmission belt to impose a tension t = T0 on the slack strand, the tension T exerted on the taut strand of the transmission belt is then calculated from the radius of the receiving pulley, the receiving torque C N , negative by convention, and the stabilized voltage T0 of the soft strand.

[0020] In another embodiment, when the drive pulley (R) rotates clockwise, the tension T exerted on the taut strand (12) is defined by: ^ = ^^ −^ ^ ^ ^ .

[0021] In another embodiment, in step c), the tensions t, T exerted on the slack and taut 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, in step d), the sliding angle αG is calculated by the relation: ^ ^ = . ^^ ^ ^ ^^ ; µ being a known dynamic friction coefficient of the transmission belt on the pulleys.

[0023] In another embodiment, in step f), the abrasion rate πab is defined by the relationship: ^ "#$ .^ d $ %&%"' ^= ! ( ; m0 being an initial mass of the transmission belt, m loss being a mass loss of the transmission belt for a single turn of belt on pulleys and N cycle being the number of turns made by the belt during a given operating time of the transmission system.

[0024] In another embodiment, the transmission belt being a belt provided with at least one tooth extending longitudinally, the mass loss is defined according to the relationship: ^^^^^a height abrasion, n d being a number of teeth of the belt, h d being a height of the teeth, α being an angle formed by a vertex of a tooth, ρ being the density of the belt and L being the length of the belt.

[0025] In another embodiment, the abrasion height h a is defined by the relation: ℎ −6 11 !−"^ = ^^. ^^.10 .µ . .; kR ^ 2.^ .% .ℎ .tan^ being the Archard coefficient, dG $ ^ ^ 2 ^ being a sliding distance of the transmission belt on a given pulley and µ being a dynamic friction coefficient of the belt on the pulleys and R i being the radius R R of the drive pulley or radius R N of the receiving pulley, the given pulley being one of the at least two pulleys.

[0026] In another embodiment, the transmission belt being a flat belt, the mass loss mloss is defined according to the relation: ^^^^^ = ℎ). *. +. , ;h a being an abrasion height, ρ being the density of the belt, L being the length of the belt and B being the width of the flat belt.

[0027] In another embodiment, the abrasion height h a is defined by the relation: ℎ^ = ^^. ^^ 10 .1 µ . ^ . !−"2.^$., ; kR being the Archard coefficient, dG being the sliding distance of the transmission belt on a given pulley, µ being a dynamic friction coefficient of the belt on the pulleys, B being the width of the flat belt and R i being the radius R R of the drive pulley or radius R N of the receiving pulley, the given pulley being one of the at least two pulleys.

[0028] In another embodiment, the sliding distance d G of the transmission belt is calculated, for a given pulley, from the radius of the pulley and the sliding angle α G of the transmission belt on the pulley, so that the sliding distance dG is defined by the relation: ^^ = ^- . ^.

[0029] In another embodiment, the transmission belt being a belt provided with teeth extending longitudinally, for each of the pulleys, a shear stress per tooth σ R_d , σ N_d of the transmission belt is calculated from the radius R R , R N of a given pulley, of the tension t, T exerted on each of the slack and taut strands of the transmission belt, of a winding angle β R , β N of the transmission belt on the given pulley and a number of teeth n d of the belt.

[0030] In another embodiment, the shear stress σ N_d of the ( ^−^ ^ belt on the driven pulley is defined by the relation: ^ ^_^ = ) ; and the shear stress per tooth σR_d of the transmission belt on the drive pulley is defined by the relation: ^ (^−^ ) ^ ^ _^ = − ^ ^ .^ ^ . ^ ^ .

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

[0032] In another embodiment, in step e), the energy efficiency η is calculated from the radius RN, RR of each of the pulleys, the rotation speed ωR, ωN of the pulleys and the receiving torque CN, so that the energy efficiency η is defined by: ^ =^ ^ .^ ^ ^ ^ .^ ^ .

[0033] In another embodiment, the transmission system comprising an electrical power sensor, the energy efficiency η is calculated, in step e), from an electrical consumption P elec of the driving pulley, measured by said electrical power sensor, of an electromechanical efficiency ρelec_motor of an electric motor rotating said driving pulley, of the rotation speed ω N of the receiving pulley and the receiving torque C N , so that the energy efficiency η is defined by: ^ =|^ ^ .^ ^ | ^^^^^_^^^^^. ^^^^ .

[0034] In another embodiment, for each of said pulleys, a sliding speed V slip_R , V slip_N of the transmission belt is distributed between said pulleys, said sliding speed V slip_R , V slip_N being calculated from the radius of each of the pulleys and the rotation speed ω R, ω N of each of the pulleys, so that the sliding speed V slip_N of the belt on the pulley ^ trice is defined by the relation: ! ^ .& −^ .& receipt ^ ^ ^ "#$% ^ = 2 ; and the sliding speed Vslip_R of the belt on the drive pulley is defined by the relation: ! "#$%_^ = ^ ^ .& ^ −^ ^ .& − ^ 2 .

[0035] The invention is part of a sustainable development approach, in particular by enabling 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 with reference to the appended drawings in which:

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

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

[0039] Figure 3 shows a schematic view of an example of a transmission belt, in particular a ribbed V-belt, used in the transmission system of Figure 1 or Figure 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] Figure 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 driving pulley R and another of the pulleys is a receiving pulley N (for the Anglo-Saxon terms “driveR” for motor and “driveN” for receiver).

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

[0043] It is understood that the driving pulley R is the pulley which is rotated to drive the transmission belt 10 via a driving torque CR and the receiving pulley N is the pulley which is driven by the transmission belt 10 and which undergoes a receiving torque CN. Furthermore, the driving pulley R rotates with a rotation speed ω R and the receiving pulley N rotates with a rotation speed ω N .

[0044] In the following, it is assumed that the drive pulley R rotates in a clockwise direction (arrow CW) and that the angles and torques are positive in this clockwise direction. In such a configuration, the taut 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, we will consider that the receiving couple C N of the driven pulley is negative when power is taken from the transmission, thus braking the driven pulley N. As a result, the engine torque C R is positive.

[0046] In a configuration where the position of the slack 11 and taut 12 strands is reversed compared to the configuration described above, it is understood that the receiving torque C N is positive and that the engine torque C R is negative. This configuration is not described in the following.

[0047] With reference to Figure 2, the transmission system 1 may comprise 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 T0 of the belt 10. The stabilized tension T0 is the tension that exists in the belt when the transmission system is not transmitting any torque.

[0048] In the following, it will be specified whether the tensioner 20 is considered to monitor the operation of the transmission system 1. In the absence of an indication, it must 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 different intrinsic parameters. These parameters can be the length L of the belt, the width B of the belt, the density ρ 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 trapezoidal belt or a flat belt. The belt 10 may comprise traction cords 16 embedded in the belt 10, these traction cords extending longitudinally in the belt 10.

[0051] Furthermore, for a given transmission belt 10 and whether it comprises traction cords 16 or not, a longitudinal modulus EA, specific to the belt, can be determined. This longitudinal modulus EA is homogeneous to the Young's modulus and to the section of the traction cords 16 or of 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 of the belt 10. In such a case, additional parameters may be considered to define the belt 10. For example, the number of teeth n d , the height of the teeth h d or the angle α formed by the vertex 17 of each of the teeth 15 can 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 represents a block diagram of a method 100 for monitoring the operation of a transmission system 1 as described previously, that is to say with at least two pulleys R, N and a transmission belt 10 mounted on these pulleys R, N. It is understood that the number of receiving pulleys N is not limited.

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

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

[0057] In a step b), or step 104, a receiving torque CN for the receiving 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 exerted on a slack strand 11 of the transmission belt 10 and a tension T exerted on a taut strand 12 of the belt 10 are determined. Step 106 can be carried out before, after or simultaneously with either of steps 102 and 104.

[0059] In a step d), or step 108, a sliding angle αG of the transmission belt 10 on one of the pulleys R, N is determined from the data determined in step c), or step 106.

[0060] In a step e), or step 110, an energy efficiency η of the transmission system 1 is calculated from the data determined in steps a) and b), or 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 π ab of the transmission belt 10 is calculated from the radii RR , R N pulleys and data determined in steps c) and d), or 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 step g), or step 114, the calculated value of the abrasion rate π ab is compared to at least a first given threshold value and the calculated value of the energy efficiency η is compared to at least a second given threshold value.

[0063] In a step h), or step 116, a warning is generated when one or other of the calculated values ​​of the abrasion rates πab and energy efficiency η is respectively greater than or less 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 through a computer system or network. The warning makes it possible to indicate to an operator the state of the system, whether its operation can be considered normal or not.

[0064] In step 114, the abrasion rate πab may be compared, in addition to the first threshold value S1, to a third threshold value S3 so as to define three ranges of values ​​G1, G2, G3. The third threshold value S3 may be lower or higher than the first threshold value S1. For example, a first range of values ​​G1 includes values ​​that are greater than or equal to the first threshold value S1, such that S1 ≤ G1. A second range of values ​​G2 includes values ​​that are lower than the first threshold value S1 but greater than or equal to the third threshold value S3, such that S3 ≤ G2 < S1. 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 πab is included in one of the ranges of values ​​G1, G2, G3.

[0065] The same can be applied for the energy efficiency η. That is, at step 114, the energy efficiency η 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 ​​P1, P2, P3. The fourth threshold value S4 may be lower or higher than the second threshold value S2. For example, a first range of values ​​P1 comprises values ​​which are greater than or equal to the second threshold value S2, so that S2 ≤ P1. A second range of values ​​P2 comprises values ​​which are lower than the second threshold value S2 but greater than or equal to the fourth threshold value S4, so that S4 ≤ P2 < S2. Finally, a third range of values ​​P3 comprises values ​​which are lower than the fourth threshold value S4, so that P3 < S4. Thus, in step 116, a specific warning may be generated when the calculated value of the energy efficiency η is included in one of the ranges of values ​​P1, P2, P3.

[0066] Having multiple ranges or value ranges allows the warning to be broken down into multiple levels. These levels can, for example, depend on the severity of the system's malfunctioning state.

[0067] At step 102, the rotation speed ωR, 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 ωR, ωN. The rotational speed ωR 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 receiving torque CN can be calculated from the radius RR, RN of each of the driving pulleys R and receiving pulleys N, the rotation speeds of each of the driving pulleys R and receiving pulleys N and of the longitudinal module EA of the transmission belt 10, so that, when the driving pulley R rotates in a clockwise direction, the receiving torque CN is defined by: [Math.1]

[0069] At step 104, the receiving pair C N can, alternatively, be measured by means of at least one torque sensor.

[0070] In step 106, the tensions t, T exerted on the slack 11 and taut 12 strands of the transmission belt 10 can be measured by means of at least one tension sensor. This tension sensor can be integrated into the belt with, for example, example a strain gauge or a pressure sensor, or be external to the belt with an instrumented roller for example present at the level of a tensioner.

[0071] In step 106, alternatively, the tensions t, T exerted on the slack 11 and taut 12 strands of the transmission belt 10 can be calculated, when there is no tensioner 20, from the radius of the receiving pulley R N , of the receiving couple C N , negative by convention, and a stabilized tension T0 of the transmission belt on the pulleys R, N, so that, when the driving pulley R rotates in a clockwise direction, the tension t exerted on the slack strand 11 is defined by: [Math.2]

[0072] and the tension T exerted on the stretched strand 12 is defined by: [Math.3]

[0073] The tension t of the slack strand 11, the tension T of the taut strand 12 and the stabilized tension T0 of the belt 10 are expressed in Newton.

[0074] We now consider the embodiment in which the transmission system 1 comprises a tensioner 20 installed on the slack strand 11 of the transmission belt 10 to impose a tension t = T0, almost constant, on the slack strand 11. For this embodiment, at step 106, the tension T exerted on the taut strand 12 of the transmission belt 10 can be calculated from the receiving torque CN, the radius of the receiving pulley RN and the stabilized tension T0 of the slack strand 11, so that, when the driving pulley R rotates clockwise, the tension T exerted on the taut strand 12 is defined by: [Math.4]

[0075] 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 taut 12 strands of the belt 10. Also, in the calculations involving a tension, the tension t, T calculated with tensioner 20 is used when the transmission system 1 comprises a tensioner 20.

[0076] At step 108, the sliding angle α G is calculated by the relation: [Math.5] 1 . ^ ^ ^ ^ = ^ ^ ^ ^ ^

[0077] where µ is a known dynamic friction coefficient of the transmission belt 10 on the pulleys R, N. Conventionally, the dynamic friction coefficient of the belt is determined by means of a test bench which simulates a transmission system

[0078] The slip angle αG is expressed in radians (rad).

[0079] In general, the coefficient of friction µ and the tensions t, T of the slack 11 and taut 12 strands of the belt 10 are identical whether on the driving pulley R or on the receiving pulley N. Also, the sliding angle αG on each pulley R, N is the same. It is understood that the sliding angle αG is always, independently of the pulley considered, on the outgoing side of the belt 10. In other words, on the driving pulley R, the sliding angle αG is on the side of the slack 11 strand, while on the receiving pulley N, the sliding angle α G is on the side of the stretched strand 12.

[0080] It will be noted that, for a given pulley R, N, the sliding angle αG cannot be greater than a winding angle β of the belt 10 on the pulley R, N considered, nor be less than 0. The winding angle β, like the sliding angle α G , is expressed in radians.

[0081] In addition, for each pulley R, N, a sliding zone % G can be determined. This sliding zone % G corresponds to the part of the winding angle β on which the belt 10 slides and can be defined as a ratio between the sliding angle α G and the winding angle β, according to the relation: [Math.6]

[0082] The sliding zone % G indicates how much of the belt's wrap around the pulley the belt slips. Thus, when the area value of slip % Gexceeds a predetermined threshold, an alert can be generated. For example, a first predetermined threshold can be equal to 50% and a second predetermined threshold can be equal to 80% so as to define a first range of values ​​less than 50%, a second range of values ​​between 50% and 80% and a third range of values ​​greater than 80%. A specific alert can then be generated for each range of values.

[0083] Furthermore, for a given pulley R, N, a sliding distance d G of the transmission belt can be calculated from the radius R R , R N of the pulley considered and the sliding angle of the transmission belt on this pulley so that the sliding distance d G is defined by the relation: [Math.7]^^ = ^^ . ^^

[0084] where R i is the radius R R of the driving pulley R or the radius R N of the receiving hen N.

[0085] We are now interested in calculating the energy efficiency η of the transmission system 1 of step 110. Generally, we define the energy efficiency η as being the ratio between the output power P N perceived by the receiving pulley N and the input power P R provided by the drive pulley R, which translates according to the relation: [Math.8]

[0086] The input powers P R and output P N are expressed in Watts (W), but for convenience they will be expressed more in kilowatts (kW). Although the couple C N exerted on the receiving pulley N is negative, these two powers P R and P N are positive.

[0087] Furthermore, when the output power P Nperceived by the receiving pulley N is not measured directly, it can be calculated. Also, regardless of the type of configuration of the transmission system 1, the output power P N perceived by the receiving pulley N can be calculated according to the relation: [Math.9]^^ = |^^. ^^|

[0088] In some cases, the input power P R is not known, nor measured. In such a situation, an approximate energy efficiency η app can be calculated from the radii R R , R N pulleys and rotation speeds ω R , pulleys, so that this efficiency η is defined by: [Math.10]

[0089] This allows us to give an estimate of energy efficiency in a simple way. This information is not intended to be precise but to indicate an order of magnitude when the input powers PR and output powers PN are not known.

[0090] In other cases, the transmission system 1 may include an electrical power sensor configured to measure an electrical consumption Pelec, defined as the product of the electrical voltage and the current. From this electrical consumption P elec , the input power P R supplied by the drive pulley R can be measured according to the relation: [Math.11]^^ = ^^^^^_^^^^^. ^^^^^

[0091] where ρelec_motor is the electromechanical efficiency of an electric motor rotating the drive pulley R. The electromechanical efficiency ρelec_motor of the electric motor is a known parameter, usually given by the motor manufacturer, and which may depend on a number of other parameters such as the temperature or the speed of the drive pulley R.

[0092] Also, when the transmission system 1 comprises an electrical power sensor, the energy efficiency η can be calculated, in step 110, from an electrical consumption P elec of the driving pulley R, measured by the electric power sensor, of an electromechanical efficiency ρelec_motor of an electric motor rotating the driving pulley R, of the rotation speed of the receiving pulley N, determined in step 102, and the receiving torque C N , determined in step 104, so that the energy efficiency η is defined by: [Math.12]

[0093] When the transmission system 1 includes an electric power sensor, the calculation of the energy efficiency is more accurate than in the previously described case where the input power is not known.

[0094] In still other cases, the transmission system 1 may include a torque sensor on the drive pulley R or the pulley N configured to measure the engine torque C R of the driving pulley R or the torque C N of the pulley N. From this engine torque C R and the rotation speed ω R of the drive pulley R, the input power P R provided by the drive pulley R can be calculated according to the relation: [Math.13]^^ = ^^ . ^^

[0095] Similarly, from this CN receiver torque and the rotation speed of the receiving pulley N, the output power P N exerted on the receiving pulley N can be calculated according to the relation: [Math.14]^^ = ^^. ^^

[0096] Also, when the transmission system 1 comprises a torque sensor on the driving pulley R or on the receiving pulley N, at step 110, the energy efficiency η can be calculated from the rotation speed ωR, of the pulleys R, N, determined in step 102, of the motor torque CR and of the receiver torque CN, determined in step 104, so that energy efficiency η is defined by: [Math.15]

[0097] Ploss energy losses can be defined as the difference between the input power PR supplied by the driving pulley R and the output power PN perceived by the receiving pulley N. This translates into the relationship: [Math.16]^^^^^ = ^^ − ^^

[0098] From the energy loss P loss , an economic loss C can be calculated over a given period of time by the relation: [Math.17]^ = ^^^^^. ^^^^^. ^^

[0099] where it is 1kWhrepresents the cost of a kilowatt-hour in monetary units and t y is the time expressed in hours. The economic loss C is expressed in monetary units for the duration t y .

[0100] Thus, at the end of step 110, the user can have an indication of the energy efficiency or the energy losses, or even economic losses, generated by the transmission system 1.

[0101] We are now interested in calculating the abrasion rate πab of the belt 10 of the transmission system 1 at step 112. Step 112 can be carried out simultaneously, before or after step 110.

[0102] In step 112, the abrasion rate πab is calculated as the ratio between the total mass loss mloss_tot and the initial mass m0 of the belt 10 according to the relation: [Math.18] ^ ^ ^^^^_^^^ ^^ = ^ ^

[0103] The total mass loss mloss_tot is the product of the mass loss mloss of belt 10 for a single belt turn 10 and the number of turns N cycle made by the belt 10 during the duration tF of operation of the transmission system 1. The abrasion rate πab can therefore be defined according to the relation: [Math.19]

[0104] Thus, for a given pulley R, N, a mass loss mloss 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: [Math.20]

[0105] where h a is an abrasion height, ρ is the density of the belt 10, L is the length of the belt 10, n d is the number of teeth 15, h d is the height of these teeth 15 and α is the angle of the apex 17 of tooth 15.

[0106] When the belt 10 is flat, in other words it does not have teeth 15, the loss of mass m loss of the transmission belt 10 can be defined according to the relation: [Math.21]^^^^^ = ℎ^ . ^. ^. ^

[0107] where B is the total width of the belt 10 which is flat.

[0108] The number of turns Ncycle is given in particular by the relation: [Math.22] ^ . ^ . ^ ^ = ^ ^ ^ ^^^^^ ^

[0109] The density ρ, the length L, the width B, the number nd of teeth 15, the height hd of these teeth 15 and the angle α of their summit 17 are intrinsic parameters of the transmission belt 10 and are known beforehand.

[0110] The abrasion height ha, or abraded height, of the belt 10 can be calculated from the relation: [Math.23]ℎ^ = ^^. ^. ^^

[0111] where kR is the Archard coefficient which depends on the intrinsic characteristics of the belt and the temperature and which is expressed in mm 3 / Nm (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 d G the sliding distance expressed in meters and already defined previously; the given pulley being one of the at least two pulleys R, N.

[0112] It should be noted that the abrasion height h a is calculated here for a single belt revolution.

[0113] The Archard coefficient k R is an empirical coefficient that is known for a given belt. This coefficient also generally depends on temperature.

[0114] The average contact pressure P of the transmission belt 10 on the pulley R, N will depend on the type of belt installed.

[0115] For example, when the transmission belt 10 installed on the pulleys R, N of the transmission system 1 is a belt provided 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 taut 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: [Math.24]

[0116] where nd is a number of teeth 15 of the belt 10, hd is the height of the teeth 15, α is the angle formed by the top 17 of the teeth 15, µ is the coefficient of friction of the belt 10 on the pulley considered and Ri is the radius RR of the driving pulley R or the radius RN of the receiving pulley N.

[0117] When the transmission belt 10 installed on the pulleys R, N of the transmission system 1 is a flat belt, in other words without teeth, 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 taut 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: [Math.25]^ = 10^^.11 ^ − ^ µ . ^ . ^ 2. ^^ .^

[0118] where B is the width of the flat belt and Ri is the radius RR of the driving pulley R or the radius RN of the receiving pulley N.

[0119] Optionally, a sliding speed Vslip_R, Vslip_N of the transmission belt 10 can be calculated for each of the pulleys R, N. The sliding speed Vslip_R, Vslip_N represents a relative tangential speed between the belt 10 and the pulley R, N considered. This sliding speed Vslip_R, Vslip_N can be calculated from the radius RR, RN of each of the pulleys R, N and the speed of rotation ω R , of each of the pulleys R, N, determined in step 102, so that the sliding speed V slip_N of belt 10 on the receiving pulley N is defined by the relation: [Math.26]

[0120] and so that the sliding speed V slip_R of belt 10 on the drive pulley R is defined by the relation: [Math.27] ^^. !^ − ^ . !^^^^^_^ = −2

[0121] The slip speed Vslip_R on the driving pulley R is negative because the belt 10 rotates more slowly than the driving pulley R while on the receiving pulley N, the belt 10 rotates more quickly than the receiving pulley N due to the negative receiving torque CN which will tend to brake the receiving pulley N, which explains the slipping and the slip speed Vslip_N being positive.

[0122] In the above, the slip is distributed equally and arbitrarily between the driving pulley R and the receiving pulley N.

[0123] Alternatively, the slip can be distributed entirely over one of the two pulleys R, N. In other words, when the slip is distributed entirely over the receiving pulley N, the sliding speed Vslip_N of the belt 10 on the receiving pulley N can be defined by the relation: [Math.28]

[0124] and, when the slip is entirely distributed over the driving pulley R, the slip speed V slip_R of belt 10 on drive pulley R can be defined by the relation: [Math.29]

[0125] The calculation of the sliding speed can be performed before any of steps 104 to 116 but after step 102.

[0126] Optionally, a slip rate τ slip_R , τ slip_N of the transmission belt 10 can also be calculated for each of the pulleys R, N. This slip rate τ slip_R , τ slip_N can be calculated from the radius R R , R N of each of the pulleys R, N and the rotation speed ω R , of each of the pulleys R, N, determined in step 102, so that the slip rate τ slip_N of belt 10 on the receiving pulley N is defined by the relation: [Math.30]

[0127] and so that the slip rate τslip_R of the belt 10 on the drive pulley R is defined by the relation: [Math.31] ^. ^ − ^ . ^ ^ ^ ^ ^ ^ ^^^^_^ = − 2. ^^. ^^

[0128] As for the sliding speed, the slip is distributed in the above in an equivalent and arbitrary manner between the driving pulley R and the receiving pulley N.

[0129] Alternatively, the slip can be distributed entirely over one of the two pulleys R, N. In other words, when the slip is distributed entirely over the receiving pulley N, the slip rate τ slip_N of belt 10 on the receiving pulley N can be defined by the relation: [Math.32]

[0130] and, when the slip is entirely distributed over the driving pulley R, the slip rate τ slip_R of belt 10 on drive pulley R can be defined by the relation: [Math.33] ^. ^ − ^ . ^ ^ ^ ^ ^ ^ ^^^^_^ = − ^^. ^^

[0131] The calculation of the slip rate may be performed before any of steps 106 to 116 but after step 104.

[0132] For each of the pulleys R, N, the sliding rate τ slip_R , τ slip_N can be compared to a predetermined threshold value. When the value of the slip rate τ slip_R , τ slip_N is greater than the corresponding threshold value, an alert may be generated in a manner similar to that implemented in step 116.

[0133] It has further been observed that at a slip rate greater than 10%, the transmission belt 10 will tend to heat up, accentuating its degradation.

[0134] Optionally, for each of the pulleys R, N, a shear stress per tooth σ R_d , σ N_d of the transmission belt 10 can also be calculated, when the belt 10 has teeth 15. This shear stress per tooth σR_d , σ N_d can be calculated from the radius R R , R N of each of the pulleys R, N, of the tension t exerted on the slack strand 11, of the tension T exerted on the taut strand 12, the tensions t, T being determined in step 104, and of the winding angle β R of the belt 10 on the drive pulley R or of the wrap angle β N of the belt on the pulley N, as well as the number of teeth 15 of the belt 10, so that the shear stress σN_d of the belt 10 on the receiving pulley N is defined by the relation: [Math.34]

[0135] and so that the shear stress σ R_d of belt 10 on drive pulley R is defined by the relation: [Math.35]

[0136] Calculation of the shear stress per tooth σ R_d , σ N_d can be performed before any of steps 106 to 116 but after step 104.

[0137] When the shear stress per tooth σR_d, σN_d becomes too great, the tooth(s) 15 of the belt shear and a tooth tearing or cord tearing phenomenon may occur.

[0138] For each of the pulleys R, N, the shear stress per tooth σR_d, σN_d can be compared to at least one predetermined threshold value. When the value of the shear stress per tooth σR_d, σN_d is greater than the value corresponding threshold, an alert can be generated in a similar manner to that implemented in step 116. Note that the predetermined threshold values ​​for the shear stress per tooth σ R_d , σ N_d are dependent on the belt 10, in particular on the type of profile of the teeth 15 of the belt 10.

[0139] Generally speaking, it should be noted that all the calculations described above can be carried out by a control unit. This control unit can, for example, be a computer system.

[0140] 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 or a hydroelectric power plant installation. The method according to the invention is therefore of interest for industrial activities where shutting down an installation for breakdowns or maintenance is costly. The transmission systems of a motor vehicle or similar are, for example, little concerned by the method according to the invention.

[0141] In light of the above, thanks to the method according to the invention, the operation of the improved transmission system is monitored by continuously monitoring the performance of the transmission system. Generally speaking, any belt mounted on pulleys wears over time, whether through a reduction in its tension between the pulleys which generates slippage of the belt on a pulley and therefore friction or excessive torque which also generates slippage, and thus sees the performance of the transmission system decrease over time. The invention also makes it possible to detect an abnormal change in these performances. Indeed, the input data, such as the radii of the pulleys, their respective rotation speed, the tensions of the slack and taut strands of the belt and the angle of slippage of the belt on a pulley, are easily accessible by calculation, measurements or indication from the manufacturer.These input data allow to determine in a simple way a level of abrasion of the belt and an energy efficiency of the transmission system which are important parameters to determine if the transmission system is in normal operation or not, in other words if it is necessary to plan a maintenance or not of the transmission system by replacing one or other of its elements like the belt or a pulley.

[0142] Another advantage of the method according to the invention is to provide a value of the abrasion level and energy efficiency in real time using simple numerical models and algorithms.

Claims

Claims [1] 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 receiving pulley (N), the method comprising the following steps: a) determining (102) a rotation speed ω R , of each of the pulleys (R, N); b) determine (104) a receiving torque C N for the receiving pulley (N); c) determining (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) determining (108) a sliding angle α Gof said transmission belt on one of said pulleys from the data determined in step c); e) calculating (110) an energy efficiency η of the transmission system (1) from the data determined in steps a) and b); f) calculating (112) an abrasion rate π ab of said transmission belt from the spokes (R R , R N ) pulleys and data determined in steps c) and d); g) compare (114) the calculated value of the abrasion rate π abto at least one first given threshold value and compare the calculated value of the energy efficiency η to at least one second given threshold value; and h) generating (116) a warning when one or the other of said at least one first and at least one second threshold values ​​is exceeded. [2] The method of 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 rotation speeds ωR, of each of the driving (R) and receiving (N) pulleys and of a longitudinal module EA of the transmission belt. [3] Method according to claim 2, in which, when the driving pulley (R) rotates in a clockwise direction, the receiving torque CN, being negative by convention, is defined by: [4] Method according to claim 1, wherein, in step b), the receiving couple C Nis measured by means of at least one torque sensor. [5] Method according to any one of claims 1 to 4, in which, in step c), the tensions t, T exerted on the slack (11) and taut (12) strands of the transmission belt (10) are calculated from the radius of the receiving pulley (R N ), of the receiving couple C N , negative by convention, and a stabilized tension T0 of the transmission belt on said pulleys (R, N). [6] Method according to claim 5, in which, when the drive pulley (R) rotates in a clockwise direction, the tension t exerted on the slack strand (11) is defined by: and the tension T exerted on the stretched strand (12) is defined by: [7] Method according to any one of claims 1 to 4, wherein the transmission system (1) comprising a tensioner (20) installed on the slack strand (11) of the transmission belt (10) to impose a tension t = T0 on said slack strand (11), the tension T exerted on the taut strand (12) of the transmission belt (10) is then calculated from the radius of the receiving pulley (RN), the receiving torque CN, negative by convention, and the stabilized tension T0 of the slack strand. [8] Method according to claim 7, wherein, when the driving pulley (R) rotates in a clockwise direction, the tension T exerted on the taut strand (12) is defined by: [9] Method according to any one of claims 1 to 4, in which, in step c), the tensions t, T exerted on the slack (11) and taut (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] Method according to any one of claims 1 to 9, wherein, in step d), the slip angle α G is calculated by the relation: µ being a known dynamic friction coefficient of the transmission belt on the pulleys (R, N). [11] Method according to any one of claims 1 to 10, in which, in step f), the abrasion rate πab is defined by the relation: m0 being an initial mass of the transmission belt (10), m loss being a mass loss of the transmission belt for a single turn of the belt on the pulleys and N cyclebeing the number of turns made by the belt during a given operating time of the transmission system (1). [12] Method according to claim 11, in which, the transmission belt being a belt provided with at least one tooth extending longitudinally, said loss of mass m loss is defined according to the relation: h a being an abrasion height, n d being a number of teeth of the belt (10), h d being a height of said teeth, α being an angle formed by a vertex (17) of a tooth (15), ρ being the density of the belt and L being the length of the belt. [13] The method of claim 12, wherein the abrasion height ha is defined by the relation: kR being the Archard coefficient, dG being a sliding distance of the transmission belt on a given pulley and µ being a dynamic friction coefficient of the belt on the pulleys and Ri being the radius RR of the driving pulley (R) or the radius RN of the receiving pulley (N), said given pulley being one of said at least two pulleys (R, N). [14] The method of claim 11, wherein, the transmission belt being a flat belt, said mass loss mloss is defined according to the relationship: + ^,^^ = ℎ) .1.

2. @ h a being an abrasion height, ρ being the density of the belt, L being the length of the belt and B being the width of the flat belt. [15] The method of claim 14, wherein, the abrasion height h a is defined by the relation: kR being the Archard coefficient, dG being a sliding distance of the transmission belt on a given pulley, µ being a dynamic friction coefficient of the belt on the pulleys, B being the width of the flat belt and Ri being the radius RR of the driving pulley (R) or the radius RN of the receiving pulley (N), said given pulley being one of said at least two pulleys (R, N). [16] Method according to any one of claims 13 or 15, wherein the sliding distance dG of the transmission belt (10) is calculated, for a given pulley, from the radius of said pulley and the sliding angle αG of the transmission belt on said pulley, so that the sliding distance dG is defined by the relation: ^ $ = ^^ . #$ [17] Method according to any one of claims 1 to 13, in which, the transmission belt being a belt provided with teeth extending longitudinally, for each of said pulleys (R, N), a shear stress per tooth σ R_d , σ N_d of the transmission belt (10) is calculated from the radius R R , R N of a given pulley (R, N), of the tension t, T exerted on each of the slack (11) and taut (12) strands of said transmission belt, of a winding angle β R , β N of said transmission belt on said given pulley and of a number of teeth n d of the belt. [18] The method of claim 17, wherein the shear stress σ N_d of the belt on the receiving pulley (N) is defined by the relation: ( ^ − ^) 1 ^ ^_^ = ^ . ^. ^^ ^^ and the shear stress per tooth σ R_dof the transmission belt on the drive pulley (R) is defined by the relation: [19] The method of claim 18, wherein the calculated value of the shear stress per tooth σ R_d , σ N_d is compared to at least one predetermined threshold value, so that an alert is generated when said calculated value of the shear stress per tooth is greater than said at least one predetermined threshold value. [20] Method according to any one of claims 1 to 19, wherein, in step e), the energy efficiency η is calculated from the radius RN, RR of each of the pulleys, the rotation speed ωR, of said pulleys (R, N) and of the receiving torque CN, so that the energy efficiency η is defined by: A = ^^ . ^^ ^^ . ^^[21] Method according to any one of claims 1 to 19, in which, the transmission system comprising an electrical power sensor, the energy efficiency η is calculated, in step e), from a consumption electric P elec of the driving pulley (R), measured by said electrical power sensor, with an electromechanical efficiency ρ elec_motor of an electric motor rotating said drive pulley (R), of the rotation speed of the receiving pulley and the receiving torque C N , so that the energy efficiency η is defined by: | ^ | A = ^. ^^ 1 / ^ / -_C,D,E. F / ^ / - [22] Method according to any one of claims 1 to 21, in which, for each of said pulleys (R, N), a sliding speed V slip_R , V slip_N of the transmission belt (10) is distributed between said pulleys, said sliding speed V slip_R , V slip_Nbeing calculated from the radius of each of the pulleys and the rotation speed ω R , ω N of each of the pulleys, so that the sliding speed V slip_N of the belt on the receiving pulley (N) is defined by the relation: ^ . ^ − ^ . ^ G = ^ ^ ^ ^ ^^^^^ 2 and so that the sliding speed V slip_R of the transmission belt (10) on the drive pulley (R) is defined by the relation: ^ ^. ^^ − ^ . ^ G = ^ ^ ^^^^_^ − 2

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