METHOD AND DEVICE FOR DETERMINING THE REMAINING LIFETIME OF A GEARBOX

Description

[0001] The invention describes a method and a device for determining the remaining service life of a component of a gearbox and a gearbox.

[0002] A gearbox has at least one gear and several bearings, usually rolling bearings. These components are subject to wear during operation, which depends on various factors. Therefore, the gearbox design is based on a typical load, which also determines its rated service life.

[0003] When maintaining technical systems, such as a gearbox, there are several approaches that can be pursued. The goal is to prevent component failure, meaning not waiting to replace the component until it fails.

[0004] Predictive maintenance has therefore increasingly come into focus. For example, in predicting bearing damage, it is known to use a microphone to record the running noise of a rolling bearing in order to detect irregularities in the rolling behavior of the rolling elements. Another well-known predictive method registers vibrations in the bearing, for example using accelerometers, to detect unusual oscillations. This allows damage to be detected early and the component to be replaced before it actually fails.

[0005] Various methods are also known for gear teeth; in particular, vibration analysis allows for accurate predictions.

[0006] However, this method can only determine whether damage is already present or developing. Unless abnormal noises or vibrations are detected, it cannot provide a direct indication of the expected remaining lifespan.

[0007] A disadvantage of the known methods is that, in principle, a sensor is required for each component to be examined, and ideally, each sensor should only detect that specific component. Therefore, even a small system or a multi-stage gearbox would require a large number of sensors. To minimize the number of sensors, it is known to provide measuring points on the components to which a suitable sensor can be attached externally. A measurement is taken and recorded over a predetermined period, such as one minute, for later analysis. A technician works through all the measuring points sequentially, moving from one to the next. For large systems with many measuring points, it is therefore common practice to perform these measurements at intervals of several weeks or months. However, this only allows for imprecise predictions, especially since damage events can develop more rapidly than the interval duration.

[0008] From the DE 10 2018 214 099 A1 The closest state of the art is a method for directly determining a theoretical damage to a component.

[0009] From the US 2017 / 0 082 188 A1 A lubrication system for a gearbox is known.

[0010] From the DE 10 52 200 A A control system for a continuously variable transmission is known.

[0011] From the US 2004 / 0 122 618 A1 An aging indicator is known for a component.

[0012] From the EP 1 744 934 B1 A method for controlling an automated motor vehicle powertrain is known.

[0013] From the DE 102 22 187 A1 A method for determining remaining usage intervals is known.

[0014] From the US 2011 / 0 106 510 A1 A method for diagnosing faults and damage to gearboxes is known.

[0015] From the US 2014 / 379 199 A1 A method for operating a motor vehicle is known which has at least one component that is subject to usage-dependent aging.

[0016] The invention therefore aims to improve and simplify the prediction of remaining service life.

[0017] This problem is solved by a method according to claim 1 and a device according to claim 13.

[0018] The inventive method for determining the remaining service life of a component of a gearbox is, in a unique manner:Parameters of the gearbox and the component are determined, wherein the parameters of the gearbox and the components include, for example: type and type of rolling bearings, number of teeth of the gears, overall gear ratio, and a nominal service life of the component is determined from the parameters, wherein the nominal service life is specified on the basis of a nominal speed and a nominal torque, during operation repeatedly: a current load state of the gearbox is recorded, wherein the load state also includes the direction of rotation, for each direction of rotation and / or each damage mechanism a partial damage of the component is calculated from the load state, wherein calculated partial damages are summed to a damage and added to the previous damage and stored in a time history.and after a predetermined number of partial damage calculations: by linear regression of the damage progression and extrapolation of the regression line to the nominal service life, a remaining service life of the component is determined.

[0019] The advantage lies in the fact that recording the current load state of the gearbox is sufficient to determine the remaining service life of a gearbox component. It is irrelevant which component's remaining service life is to be calculated. Therefore, separate sensors or measuring points are not required for each component. Furthermore, due to the accumulation of damage and the extrapolation of the regression, the calculated remaining service life exhibits only minor fluctuations under changing operating conditions.

[0020] Another advantage over the state of the art is that instead of detecting damage, the system provides an estimate of the remaining service life. This allows for better maintenance planning. By recording the current load condition, the remaining service life is dynamically adjusted to changing operating conditions, resulting in a very precise estimate.

[0021] The calculation is performed even if the gearbox is permanently operated in only one direction of rotation. The unused direction of rotation is then factored into the damage calculation as zero. Overall, this simplifies implementation, as it eliminates the need to first determine whether and in which single direction the gearbox is operated.

[0022] It is advisable to determine the remaining service life for each component of a gearbox. This allows for an accurate calculation of the remaining service life for the entire gearbox.

[0023] In one design, a component of the gearbox is a gear or a bearing, especially a rolling bearing. These two components are subject to the greatest wear, which is why a remaining service life calculation is particularly advantageous here.

[0024] According to the invention, the rated service life of a component, in particular a bearing, is calculated as a function of a rated speed and a rated torque under continuous load. The rated service life can also be stored, for example, as a parameter in a table. In this way, a reference value is available against which the remaining service life can be calculated.

[0025] In one embodiment, to determine the nominal service life, in particular of a gear, the endpoints for fatigue strength and short-term strength are determined in a Wöhler diagram of the component for the currently considered damage mechanism, in particular tooth root damage or tooth flank damage.

[0026] According to the invention, the parameters of the gearbox and its components include, for example: the type and type of rolling bearings, the number of teeth on the gears, and the overall gear ratio. The nominal service life is specified according to the invention based on a nominal speed and a nominal torque. In addition, the parameters can include extensive data on the gearbox design, the material of the components, and / or other data that are required or helpful for calculating the service life.

[0027] In one implementation, the current load condition includes the current rotational speed and torque at the gearbox. By recording current values, an accurate remaining service life calculation is possible.

[0028] If no measurement technology can be used, or if a gearbox is operated under nearly constant conditions, a predetermined target speed and torque can be used to calculate the remaining service life instead of measured values. This allows, for example, a remaining service life calculation even for existing systems where no measurement technology can be retrofitted.

[0029] Alternatively, a load collective can be used. This can be particularly advantageous when calculating the remaining service life of a gear.

[0030] In one embodiment, the current load condition is determined by measuring the rotational speed and torque at a gearbox. The advantage of the invention is that the measurement location is irrelevant, since the measured values ​​for the respective component are converted based on the parameters. In this way, the number of sensors per gearbox is very low, making the remaining service life calculation simpler and more cost-effective.

[0031] The rotational speed can be measured, for example, using an encoder or another known speed measuring device. Alternatively, the speed can be derived from a motor controller, where the speed may already be available. This allows for very precise speed measurement. Furthermore, using parameters such as the gear ratio of the individual gears, the rotational speed for each component of the gearbox can be derived from this rotational speed.

[0032] Torque can be determined directly, for example, using a strain gauge on a gearbox shaft. However, torque can also be determined indirectly, such as via the electrical power of an electric drive motor. This can be done, for instance, by measuring current and voltage on a supply line to the electric motor. In this way, the actual torque at each component can be calculated by conversion using the parameters.

[0033] Preferably, the speed and / or torque measurement is performed on the output shaft or the input shaft of the gearbox. These shafts are easily accessible, allowing for simple installation of the measuring device and sensors. Furthermore, it may be possible to retrofit measuring equipment for acquiring the measured values.

[0034] As mentioned previously, only one shaft of a gearbox requires speed and torque measurement. The current load state of the component is determined by converting the measured values ​​based on the parameters. In this way, a remaining service life can be calculated for each component of a gearbox, and especially for all components, with just one measurement.

[0035] In one implementation, the remaining service life is calculated in a dedicated processing unit as soon as new measurements are transmitted. This enables continuous, or at least real-time, remaining service life calculations. The processing unit can, for example, be combined with the measurement technology in a measuring device attached to the gearbox. This allows for simple, local monitoring of the gearbox.

[0036] In an advantageous embodiment, the calculation unit is designed as a central calculation unit. In particular, the measured values ​​from multiple gearboxes can be transmitted to this central calculation unit. This has the advantage that one calculation unit can perform the remaining service life calculation for several gearboxes or systems. In this way, only one calculation unit is required, thus reducing overall installation costs.

[0037] In one implementation, the uniquely determined parameters and nominal lifetimes are stored in a parameter database, and the computing unit has access to this database. This allows, for example, a simple update of the parameter values, independent of the computing unit.

[0038] Such a parameter database can be connected to a central calculation unit or to individual calculation units, each separate for a gearbox.

[0039] It is particularly advantageous if the parameter database is designed as a central parameter database. This prevents redundancy of parameter values. In a system with several identical gearboxes, only one parameter database is needed, which can be accessed by all individual gearboxes or a central processing unit.

[0040] In one implementation, the recorded load conditions are transferred to a measurement database to which the processing unit has access. This allows for the measurement data to be stored separately from the processing unit.

[0041] It is particularly advantageous if the measurement database is designed as a central database. This prevents redundancy in measurement databases when multiple transmissions are present. This allows the measurement data from several transmissions to be stored in a single measurement database.

[0042] The calculation unit, parameter database, and measurement database can all be centrally located for a single plant. This means that, for example, only one of these units is needed in a complex system. The calculation of the remaining service life of all components is performed centrally, for instance, in a control room or data center on site.

[0043] However, "central" can also mean that at least one of the units is located remotely, for example, across multiple sites. In this case, the measurement data from several locations can be centrally collected at one location. The transmission of the measurement data can then take place via an intranet or the internet.

[0044] However, "centralized" can also mean that at least one unit is available as a cloud application on the internet. In this way, remaining service life calculations can be performed entirely as a service, with data storage and the calculation itself running in the cloud. The advantage of this approach is that only minimal on-site hardware installation is required for the remaining service life calculation, especially if existing systems are suitable for recording the current load state, such as a motor controller speed sensor and existing power measurement equipment. Retrofitting existing systems is therefore very cost-effective.

[0045] It is advantageous if each measured value in the measured value database can also be uniquely assigned to a customer and / or a system.

[0046] In one implementation, the load states are encrypted and / or compressed before transmission. This ensures data security and / or reduces the amount of data to be transmitted. This is particularly advantageous when transmitting measurement data over the internet.

[0047] The acquisition of current load conditions is typically very high-frequency. For example, the rotational speed is recorded several times per second. Direct transmission at this frequency would be impossible, especially since each of these values ​​would trigger a new calculation of the remaining service life. Therefore, in one implementation, a load equivalent and a rotational speed equivalent are calculated from several measured values ​​before being transmitted to the data database. This load equivalent and rotational speed equivalent are then transmitted to the data database for calculation at a lower frequency than the current load condition. This reduces the amount of data transmitted to the data database and thus increases the time between two transmissions and, consequently, the time between two remaining service life calculations.

[0048] Alternatively, the calculation of the load and speed equivalents could also take place on the side of a computing unit, but this would not reduce the amount of data to be transferred.

[0049] In one implementation, the method is applied to several, in particular all, components of the gearbox. The advantage of this is that it enables a precise determination of the remaining service life of the gearbox. As mentioned above, the remaining service lives of all components can be determined from the same measured values, so that the metrological effort on the gearbox is not increased.

[0050] In an embodiment where the component is a rolling bearing, the rated service life includes a rated speed and a rated torque, and the current load condition includes a current speed and a current torque, the method is characterized in that, for calculating the partial damage: A speed factor is calculated that relates the current speed to the rated speed, and a torque factor is calculated that relates the current torque to the rated torque. From these factors and the rated service life, a reference service life is calculated, and from this reference service life, the partial damage is calculated.

[0051] In this way, the current partial damage of a rolling bearing can be determined very accurately, achieving low variance under changing operating conditions.

[0052] In an embodiment where the component is a gear, the rated service life includes a rated speed and a rated torque, and the parameters include at least one S-N diagram for each damage mechanism in both directions of rotation, and the current load condition is given as a load collective, the method is characterized in that the following steps are performed to calculate the partial damage: For each damage mechanism and direction of rotation, a permanently tolerable torque is calculated at which no damage occurs according to the damage mechanism; all measured values ​​with an amount less than the permanently tolerable torque are removed from the load collective; an equivalent rotational speed and an equivalent torque are determined from the remaining load collective; a number of load cycles is calculated from the equivalent rotational speed, in particular using the gear ratio; an equivalent tooth root stress or an equivalent tooth flank pressure is calculated from the equivalent torque depending on the current damage mechanism; a tolerable number of load cycles is calculated from the tooth root stress or the tooth flank pressure; and a partial damage is calculated from the ratio of the calculated load cycles in the load collective and the calculated tolerable number of load cycles.

[0053] In this way, the individual partial damages to a gear tooth, and consequently the overall damage to the gear tooth, can be calculated very precisely. These partial damages comprise two damage mechanisms: tooth flank damage due to flank pressure and tooth root damage due to root stress. Both damage mechanisms are also direction-dependent. Therefore, to determine the extent of damage to a gear tooth, four different partial damages must be calculated and added together.

[0054] The invention also includes a method for determining the remaining service life of a gearbox according to claim 13, wherein a remaining service life for at least one component of the gearbox is determined according to a method for determining the remaining service life of a component described above. From the remaining service lives of the individual components, a total remaining service life of the gearbox is determined. In this way, a representation, for example in a virtual representation of a system, can be simplified.

[0055] In one configuration, the total remaining service life can correspond to the shortest determined remaining service life of the individual components. In this way, the failure of a gearbox component can be reliably prevented.

[0056] The invention also includes a device for determining the remaining service life of a gearbox, with a measuring device for recording the speed and torque of the gearbox and with a calculation unit for carrying out a method according to the invention.

[0057] In one embodiment, the device includes a parameter database for storing the gearbox parameters, in particular wherein the parameter database is a central database accessible via the internet, and the computing unit for retrieving parameters is connected to the parameter database. This enables centralized maintenance of the parameters, thus reducing on-site installation effort.

[0058] In one embodiment, the device includes a measurement database in which the measured values ​​acquired by the measuring device are stored, in particular wherein the measurement database is a central database accessible via the Internet, and the processing unit for retrieving measured values ​​is connected to the measurement database. In this way, the calculation of the remaining service life of several components can be bundled in one processing unit, thereby reducing installation effort.

[0059] In particular, the remaining lifespan can be offered as a service in this way.

[0060] The invention is described in more detail below with reference to exemplary embodiments and the accompanying drawings.

[0061] It shows: Fig. 1 : a block diagram of a device according to the invention for determining the remaining service life of a gearbox, Fig. 2: a flowchart of a method according to the invention, Fig. 3 : a flowchart of a procedure for determining the partial damage of a rolling bearing, Fig. 4 : a flowchart of a procedure for determining the partial damage of a gear, Fig. 5 : a diagram to illustrate the determination of partial damage to a gear, and Fig. 6 : a damage progression of a component with extrapolated remaining service life.

[0062] The Fig. 1Figure 1 shows a block diagram of a device 1 according to the invention for determining the remaining service life of at least one component of a gearbox 2. The gearbox 2 can be any type of gearbox and may, for example, have one or more gear stages. A gear stage comprises a toothed section, for example, with two gears. The gears used can be, for example, spur or helical gears, bevel gears, or other gears. A gear is generally mounted on a shaft, which is rotatably supported by one or two rolling bearings. A component within the meaning of the invention is each rolling bearing and each toothed section of the gearbox. Accordingly, a gearbox has several components for which a remaining service life calculation can be performed.

[0063] The device includes a measuring device 3, which is arranged on the gearbox 2. In this example, the device further includes a measured value database 4, a parameter database 5, a calculation unit 6, and a display unit 7.

[0064] The measuring device 3 is arranged on the gearbox to detect torque and rotational speed. To carry out the method according to the invention, it is sufficient to detect only one rotational speed and one torque.

[0065] The rotational speed can be detected, for example, at the input shaft, the output shaft, or another shaft within the gearbox, using a suitable speed sensor, such as a Hall sensor. In principle, it is also possible to obtain a speed reading from the driving motor. Particularly with electric motors, the motor controller can provide a speed reading.

[0066] The current torque can be measured, for example, at the input, output, or another shaft within the gearbox using a suitable torque sensor, such as a strain gauge. Alternatively, the torque can also be determined indirectly, for example, via the instantaneous electrical power of a driving electric motor.

[0067] The measuring device 3 can be configured to record measured values ​​at short intervals and transfer them to the measured value database 4.

[0068] Parameter database 5 contains comprehensive data about the gearbox. This includes the number of teeth on all gears and thus the gear ratios of all stages. From this data, the rotational speed of all components can be calculated from a single measured speed. For example, if the rotational speed at the drive is recorded, the rotational speed of each rolling bearing and each gear can be calculated. Similarly, the torque for each component can be calculated from a single recorded torque value. Parameter database 5 also contains data on the strength and material of the components.

[0069] The calculation unit 6 is connected to the measurement database 4 and the parameter database 5 in order to access their data for the calculation.

[0070] The calculation unit 6 is configured to execute a method according to the invention. For this purpose, the calculation unit 6 accesses the parameter database 5 and the measurement database 4. A calculated remaining service life value is then stored in the measurement database 4 and assigned to the component.

[0071] A display unit 7 accesses this remaining service life value and can show or represent the remaining service life of a component. For example, the display unit 7 can show an image of a component or gearbox, with the remaining service lives of the components displayed and assigned to the image. The display unit 7 can, for example, be part of or integrated into a control room. The display unit 7 can also include a mobile device and / or display or generate warnings when a component falls below or has fallen below a warning threshold for remaining service life. In this way, a component replacement can be initiated.

[0072] It can also be advantageous to process the remaining service lives directly in a maintenance planning program. For this purpose, the maintenance planning program can, for example, have access to the measurement data database to read the remaining service lives.

[0073] The device for determining the remaining service life can form a unit assigned to the gearbox 2, with all units arranged in a common housing. However, the device can also be distributed. In this way, for example, several measuring devices 3 can be connected to a common data database 4. Thus, in a larger system, all units except the measuring devices 4 can be designed as central units and therefore exist only once. The central units can be located, for example, in a control room or a separate data center.

[0074] In one embodiment of the invention, the calculation unit 6, the parameter database 5, and the measurement database 3 can be centrally available on the internet. With this cloud application, the data is preferably located at the gearbox manufacturer or supplier, allowing the remaining service life calculation to be offered as a service. To assign the measurement values ​​to a gearbox and / or customer, they are preferably provided with a unique identifier. An advantage of this approach is that the parameter database, for example, can be very comprehensive and maintained centrally. Therefore, a complex installation of databases and computing capacity is not necessary at the gearbox's installation site, resulting in a low initial investment for implementing the remaining service life calculation. This is further enhanced by the fact that only a simple measuring device is required to record rotational speed and torque.Compared to known methods using multiple acoustic sensors, accelerometers, or measuring points, this allows for a very simple and cost-effective remaining service life calculation. This enables predictive maintenance, thereby reducing maintenance costs and the material costs for replacement parts.

[0075] In principle, all measured values ​​from the measuring device can be transferred to the measured value database 4. However, if the measured value database 4 is remote, for example, connected via the internet (cloud), a high data load can occur with a high sampling frequency and / or a large number of measuring devices 3. Therefore, the measuring device 3 can perform preprocessing before the measured values ​​are transmitted. In this process, a load equivalent and a speed equivalent are calculated from several measured values ​​over a predefined time interval.

[0076] Additionally or alternatively, the measured values ​​or the load and speed equivalents can be compressed and / or encrypted before transmission.

[0077] If two rolling bearings supporting a shaft are identical in construction and have the same current operating time, the remaining service life of one rolling bearing can also be transferred to the other rolling bearing. This should be identical and would also be calculated identically using the method according to the invention.

[0078] The Fig. 2Figure 1 shows a flowchart of a method according to the invention for determining the remaining service life of a gearbox component. The method determines the remaining service life of a selected component. As mentioned above, this involves measuring the rotational speed and torque, but this measurement is independent of the selected component. Therefore, the method according to the invention can be carried out for each gearbox component regardless of where the measured values ​​are acquired. Naturally, the method can also be carried out for several or all gearbox components.

[0079] In a first step, parameters of the gearbox and the component for which a remaining service life is to be determined are defined once. As mentioned above, these parameters include numerous data points for the individual gears and bearings. This also includes type and catalog data on rated loads and rated speeds. Furthermore, it includes S-N diagrams for individual damage mechanisms of gear teeth. It is advantageous if the parameter database is centrally available, for example, on the internet. This allows for the maintenance of a comprehensive database that can be updated centrally. On-site installation or updates are thus unnecessary.

[0080] The parameters are also used to determine the component's rated service life, which is then stored, for example, in the parameter database. The rated service life refers to a rated speed and a rated torque.

[0081] To determine the remaining service life, the current load condition of the gearbox is repeatedly recorded during operation. This can be done, as described above, by a measuring device 3, which, for example, records the current speed and torque. If no measuring device is available, a specified target load, i.e., a target torque and a target speed, can also be used.

[0082] The calculation is triggered by the presence of a new measurement value or, if equivalents are formed from the measurement values ​​as described above, after the availability of the equivalents, which are formed over a predetermined period.

[0083] The load condition also includes the current direction of rotation. In addition, there can be various damage mechanisms for a component that must be considered separately.

[0084] In the next step 22, a partial damage to the component is therefore calculated for each direction of rotation and / or each damage mechanism based on the load state. In the simplest case, a partial damage is calculated for each of the two directions of rotation.

[0085] Step 23 checks whether all partial damages of a component have already been calculated. If not, step 22 is repeated for the remaining partial damages, for example, for the other direction of rotation.

[0086] If so, in the following step 24, the calculated partial damages are summed to form a single damage. This damage reflects the damage to the component during the currently considered period.

[0087] In the next step (25), this damage is added to the previous damage, so that a damage progression over time can be calculated from the damage values. An example of such a damage progression is shown in the Fig. 6shown. Each point on the diagram corresponds to damage calculated in this way.

[0088] Step 26 then checks whether a predetermined number of damages have been calculated. If not, the process continues with step 22.

[0089] If so, in step 27 a regression line 61 is determined through the individual damage values ​​by linear regression of the damage progression, i.e. the individual damages.

[0090] The nominal service life was determined in the first step 21 from parameters in parameter database 5 and is constant over the component's service life. The damage is given here as a percentage of the nominal service life. In the diagram of the Fig. 6The nominal service life is plotted as a horizontal line at 100%. Since damage is recorded here, 100% damage signifies component failure and a remaining service life of 0. Damage always has a temporal dimension, as a time or current operating time is known for each damage calculation. For example, damage can be calculated per minute, automatically resulting in one-minute intervals between damage values. Just as each damage value is added to the previous one, this also occurs over time, thus automatically representing progress along the time axis.

[0091] A so-called rolling window (or moving window) can also be used, whereby only a certain number of previous damage values ​​are included in the regression.

[0092] The regression line 61 is extrapolated beyond the current time TA until it intersects the horizontal line representing the nominal lifetime. The time value TV of this intersection point corresponds to the failure time TV of the component. The difference between the current time value TA and the failure time TV is the remaining lifetime RUL of the component, i.e.: RUL = TV − TA .

[0093] Through regression and extrapolation of the damage, a reliable prediction of the remaining service life is possible, which is not subject to large fluctuations even under fluctuating operating conditions.

[0094] For example, a component of the gearbox for which a remaining service life can be calculated could be a rolling bearing or a gear.

[0095] The Fig. 3 This shows a flowchart for calculating damage to a rolling bearing. The diagram in Fig. 3The steps shown thus constitute steps 22 to 24 of the procedure for determining the remaining service life of the Fig. 2 .

[0096] In a rolling bearing, there is essentially only one damage mechanism. The determined speed and torque values ​​are therefore separated according to their direction of rotation in a first step (31).

[0097] In a second step 32, a speed factor kN, which relates the current speed to the rated speed, and a torque factor km, which relates the current torque to the rated torque, are calculated separately for each direction of rotation. These factors are calculated as follows: k n = reale_gemessene_äquivalente_Drehzahl / Nenndrehzahl k m = reale_gemessenes_äquivalentes_Drehmoment / Nenndrehmoment

[0098] In the following step 33, a reference service life is calculated from these factors, which corresponds approximately to a nominal service life under the current operating conditions. Accordingly, the nominal service life from the parameter database is adjusted for the factors kN and km as follows: Bezugslebensdauer = k n × k M exp × Nennlebensdauer

[0099] The exponent exp depends on the bearing type and how the nominal service life is read from the parameter database. Beyond the bearing type, the exponent exp also takes into account the bearing's material and geometry, such as whether it is a ball, needle, or roller bearing.

[0100] In the following step 34, the partial damage to the bearing is then calculated for each direction of rotation as follows: Teilschädigung_links = Delta_t_links / Bezugslebensdauer * 100 Teilschädigung_rechts = Delta_t_rechts / Bezugslebensdauer * 100 where: Delta_t_left: Duration of rotation in the left direction of the current data set. Delta_t_right: Duration of rotation in the right direction of the current data set.

[0101] The damage is determined in the following step 35, as already described above, from the sum of the partial damages as follows: Schädigung = Teilschädigung_links + Teilschädigung_rechts

[0102] This damage then feeds into the further proceedings of the Fig. 2 according to step 25.

[0103] The Fig. 4 The diagram shows a flowchart for calculating partial damage to a gear. The procedure is described below with reference to the... Fig. 5 explained. The in Fig. 4 The steps shown thus constitute the calculation of the partial damage of step 22 of the procedure for determining the remaining service life of the Fig. 2

[0104] A gear tooth has two different damage mechanisms: flank damage and root fracture. Both are dependent on the direction of rotation, meaning that a total of four partial damages must be determined to calculate the damage to a gear tooth. According to Fig. 2 Step 22, i.e., the procedure after Fig. 4, to be performed four times.

[0105] The Fig. 4 This shows an example of how to calculate tooth root damage in the clockwise direction of rotation. Calculations for tooth flank damage and counterclockwise rotation are performed analogously.

[0106] In a first step 41, a permanently tolerable torque Mfatigue-proof is calculated for the current damage mechanism and the current direction of rotation, at which no damage occurs according to the damage mechanism. This permanently tolerable torque is determined from the data in the parameter database. The determination of the permanently tolerable torque Mfatigue-proof can be carried out using a conversion table (see step 31) and the vertex "FD" assigned to the gear teeth in the Wöhler diagram 51 assigned to the damage mechanism (see Fig. 5(top right). From the parameters, four S-N diagrams can be read for each gear tooth in the gearbox, one for each direction of rotation and one for each damage mechanism. Fig. 5 This corresponds to the dashed lines originating from point FD of the Wöhler diagram. The stress σ FD of the Wöhler diagram is plotted in the diagram of the Fig. 5 The value is transferred to the upper left and the corresponding torque is determined using the tooth root stress curve 53. This can then be transferred to the lower left into the load collective.

[0107] For tooth flank damage, the curve for tooth flank pressure 52 should be used here.

[0108] The measured values ​​of a measuring device are available as load collectives 54. In Fig. 5 The lower left shows an example of a load collective 54. The vertical dashed line represents the permanently tolerable torque M fatigue strength for this damage mechanism.

[0109] All values ​​of load spectrum 54 lying to the left of this line represent loads that are less than the fatigue-resistant torque Mfatigue-resistant. These loads do not contribute to damage. In a subsequent step 42, all measured values ​​with a value less than the fatigue-resistant torque Mfatigue-resistant are removed from load spectrum 54.

[0110] In a subsequent step 43, an equivalent rotational speed and an equivalent torque M eq are determined from the remaining load collective. Fig. 5 This equivalent torque M eq is represented as a vertical line.

[0111] In a further step 44, an equivalent number of load cycles N is calculated from the equivalent rotational speed using the parameter database, in particular using the gear ratio. This is in Fig. 5The N symbol is present in the upper right corner, and the right side is shown as an example of the direction of rotation to the right.

[0112] In a subsequent step 45, an equivalent tooth root stress or an equivalent tooth flank pressure is calculated from the equivalent torque depending on the current damage mechanism. Fig. 5 The tooth root stress is shown as an example. The equivalent torque is given in Fig. 5 The line at the top right is transferred to the diagram as a vertical line. The intersection with the tooth root stress curve 53 yields the equivalent tooth root stress σF corresponding to the equivalent torque M eq.

[0113] In a subsequent step 46, a tolerable number of load cycles NF is calculated from the equivalent tooth root stress σ F or the equivalent tooth flank pressure. This is done using the corresponding S-N diagram 51 from the parameter database. Fig. 5For illustration, a horizontal arrow from the diagram in the upper left, starting at the intersection point σF, is shown pointing towards the Wöhler diagram 51 in the upper right. The intersection point F with the Wöhler curve corresponds to this equivalent number of load cycles NF. Since the equivalent tooth root stress σF is greater than the permanently tolerable tooth root stress, the equivalent number of load cycles NF is less than the permanently tolerable number of load cycles NFD.

[0114] Finally, in step 47, a partial damage dS F,right is calculated from the ratio of the calculated load cycles N present,right in the load collective and the calculated equivalent number of load cycles NF as follows: dS F , rechts = N vorh , rechts / N F

[0115] As mentioned above, a gear tooth has two damage mechanisms: tooth root stress and flank pressure. Therefore, the procedure described above must be performed four times for each of these damage mechanisms and for each direction of rotation, i.e., for each component, in order to determine whether a gear tooth is damaged. Reference symbol list

[0116] 1 Device for calculating remaining service life 2 Gearbox 3 Measuring device 4 Measured value database 5 Parameter database 6 Calculation unit 7 Display unit 21 - 27 Procedure steps for calculating the remaining service life of a component 31 - 35 Procedure steps for calculating partial damage to a rolling bearing 41 - 47 Procedure steps for calculating partial damage to a gear 51 S-N diagram 52 Tooth flank pressure 53 Tooth root stress 54 Load spectrum 61 Damage progression M eq equivalent torque NF equivalent number of load cycles N FD permanently tolerable number of load cycles N existing, right existing number of load cycles in the current load spectrum σ F equivalent tooth root stress σ FD permanently tolerable tooth root stress

Claims

1. Computer-implemented method for determining the remaining service life of a component of a gear mechanism (2), characterized in that the following are performed only once: - parameters of the gear mechanism and of the component are determined (21), wherein the parameters of the gear mechanism and of the component comprise, for example: the nature and type of the rolling bearings, the number of teeth of the gear wheels, the overall gear ratio of the gear mechanism, and - a nominal service life of the component is determined (21) from the parameters, wherein the nominal service life is specified on the basis of a nominal rotational speed and a nominal torque, in that the following are performed repeatedly during operation: - a current load state of the gear mechanism is detected, wherein the load state also includes the direction of rotation, - for each direction of rotation and / or each damage mechanism, a partial damage on the component is calculated (22) from the load state, wherein calculated partial damages are summed (24) to form a damage, which is added (25) to the previous damage such that a damage curve over time can be formed, and in that the following is performed after a predetermined number of partial damage calculations: - a remaining service life of the component is determined (27) by linear regression of the damage curve and extrapolation of the regression line to the nominal service life.

2. Method according to claim 1, characterized in that a component of the gear mechanism is a toothing or a bearing, in particular a rolling bearing.

3. Method according to any of the preceding claims, characterized in that the nominal service life of a component is calculated as a function of a nominal rotational speed and a nominal torque under continuous load, and / or in that, in order to determine the nominal service life, the turning points for high cycle fatigue and low cycle fatigue in an S-N diagram of the component are determined for a damage mechanism, in particular tooth root damage and tooth flank damage.

4. Method according to any of the preceding claims, characterized in that the current load state comprises a current rotational speed and a current torque on the gear mechanism, a predefined target rotational speed and a predefined target torque, or a load spectrum.

5. Method according to any of the preceding claims, characterized in that the current load state is determined by measuring the rotational speed and the torque, in particular on the output shaft or the input shaft of the gear mechanism, in particular wherein the current load state of the component takes place by recalculating the measured values on the basis of the parameters.

6. Method according to any of the preceding claims, characterized in that the calculation of the remaining service life is performed in a calculation unit, in particular a central calculation unit, as soon as new measured values have been transmitted.

7. Method according to any of the preceding claims, characterized in that the parameters and nominal service lives, which are determined once only, are stored in a parameter database, in particular a central parameter database, and the calculation unit has access to the parameter database.

8. Method according to any of the preceding claims, characterized in that the detected load states are transferred to a measured value database, in particular a central measured value database, in particular wherein the load states are encrypted and / or compressed prior to being transferred, and the calculation unit has access to the measured value database, in particular wherein a load equivalent and a rotational speed equivalent are calculated from a plurality of measured values prior to being transferred to the measured value database, and the load equivalent and the rotational speed equivalent are transferred to the measured value database as the current load state for the calculation.

9. Method according to any of the preceding claims, characterized in that the component is a rolling bearing, wherein the nominal service life comprises a nominal rotational speed and a nominal torque, and wherein the current load state comprises a current rotational speed and a current torque, characterized in that, in order to calculate the partial damage: - a rotational speed factor is calculated (32), which relates the current rotational speed to the nominal rotational speed, and a torque factor is calculated (32), which relates the current torque to the nominal torque, and - a reference service life is calculated (33) from the factors and the nominal service life, and the partial damage is calculated (34) from this reference service life.

10. Method according to any of the preceding claims, characterized in that the component is a toothing, wherein the nominal service life comprises a nominal rotational speed and a nominal torque, wherein the parameters comprise at least one S-N diagram for each damage mechanism in both directions of rotation, and wherein the current load state is in the form of a load spectrum, characterized in that, in order to calculate the partial damage, the following steps are carried out: - for each damage mechanism and each direction of rotation, a continuously tolerable torque is calculated (41), at which no damage occurs according to the damage mechanism, - all measured values having an absolute value lower than the continuously tolerable torque are removed (42) from the load spectrum, - an equivalent rotational speed and an equivalent torque are determined (43) from the remaining load spectrum, - a number of load changes is calculated (44) from the equivalent rotational speed, in particular using the gear ratio, - an equivalent tooth root stress or an equivalent tooth flank pressure is calculated (45) from the equivalent torque as a function of the current damage mechanism, - a tolerable number of load changes is calculated (46) from the tooth root stress or the tooth flank pressure, and - a partial damage is calculated (47) from the ratio of the calculated load changes in the load spectrum and the calculated tolerable number of load changes.

11. Method for determining the remaining service life of a gear mechanism, wherein, for at least one component, in particular all components, of the gear mechanism, a remaining service life is determined by the method according to any of the preceding claims, and, from the remaining service lives of the individual components, an overall remaining service life of the gear mechanism is determined.

12. Method according to claim 11, characterized in that the overall remaining service life corresponds to the shortest determined remaining service life of the individual components.

13. Device for determining a remaining service life of a gear mechanism (2), comprising a measuring device (3) for detecting a rotational speed and a torque of the gear mechanism (2), and a calculation unit (6) for carrying out the method according to any of the preceding claims.

14. Device according to claim 13, characterized in that the device comprises a parameter database (5) for storing the parameters of the gear mechanism (2), in particular wherein the parameter database (5) is a central database accessible via the Internet, and the calculation unit (6) is connected to the parameter database (5) in order to retrieve parameters.

15. Device according to claim 13 or 14, characterized in that the device comprises a measured value database (4), in which the measured values detected by the measuring device (3) are stored, in particular wherein the measured value database (4) is a central database accessible via the Internet, and the calculation unit (6) is connected to the measured value database (4) in order to retrieve measured values.