Calculation device and calculation method

Abstract

To improve the calculation accuracy of fluctuation torque of a power transmission shaft.SOLUTION: An arithmetic unit (4) calculates fluctuation torque of a power transmission shaft (35) from a vibration signal output by a vibration sensor (D2) using an approximate formula that shows a relation between the fluctuation torque and the vibration calculated based on the frequency components selected from a primary component to an N-th component of mesh frequency components when a value obtained by rounding up a mesh rate between a pinion gear (36) and a drum gear (371) to an integer value is defined as N.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a calculation device and a calculation method for calculating torque fluctuations of a transmission shaft. [Background technology]

[0002] Conventionally, for the purpose of maintaining facilities equipped with rotating machines, the degree of damage (mechanical load) during operation of the rotating machines has been evaluated to estimate the remaining life of the facilities. In relation to this type of technology, Patent Document 1 discloses a method for calculating torque fluctuations based on vibrations of a transmission shaft detected by a shaft vibration detector. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-122952 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the detected vibrations contain unnecessary information such as electrical noise or vibrations in the surrounding environment, which may make it difficult to ensure sufficient accuracy in calculating the torque fluctuations of the transmission shaft with the conventional technology.

[0005] One aspect of the present invention has been made in consideration of the above-mentioned problems in the conventional art, and aims to improve the accuracy of calculating torque fluctuations of a transmission shaft. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems, a calculation device according to one embodiment of the present invention includes a calculation unit that calculates the torque fluctuations of a transmission shaft based on a vibration signal output from a vibration detection unit that detects vibrations of a first gear fixed to the transmission shaft that transmits the power of an electric motor to a rotating machine. When the meshing ratio between the first gear and a second gear that meshes with the first gear and transmits the power to the rotating machine is rounded up to an integer, the calculation unit calculates the torque fluctuations from the vibration signal using an approximation formula that shows the relationship between the vibration and the torque fluctuations calculated based on frequency components selected from the first to Nth order components of the meshing frequency components. [Effects of the Invention]

[0007] According to one aspect of the present invention, it is possible to improve the accuracy of calculating torque fluctuations of a transmission shaft. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic diagram showing a floodgate system according to an embodiment of the present invention. [Figure 2] FIG. 2 is a block diagram showing the functional configuration of the arithmetic device shown in FIG. [Figure 3] 1 is a graph showing the relationship between average torque and fluctuating torque and the machine load (operating torque). [Figure 4] 10 is a graph showing an example of a relationship between current and average torque. [Figure 5] 10 is a graph showing an example of the relationship between vibration and torque fluctuation. [Figure 6] 10 is a flowchart showing an example of a process for estimating the remaining lifespan of a water gate facility. [Figure 7] 1 is a graph showing an example of the relationship between the cumulative damage level and the remaining lifespan. DETAILED DESCRIPTION OF THE INVENTION

[0009] An embodiment of the present invention will be described below with reference to Figures 1 to 7. In this embodiment, a configuration example of a water gate system equipped with a computing device according to one aspect of the present invention will be described. However, the following description is an example of the computing device of the present invention, and the technical scope of the present invention is not limited to the illustrated example.

[0010] [Configuration of Water Gate System 1] Figure 1 is a schematic diagram showing the configuration of a floodgate system 1 according to this embodiment. The floodgate system 1 comprises a gate body 2, a floodgate opening / closing device 3, and a computing device 4. The computing device 4 executes a process to estimate the remaining lifespan of the floodgate equipment, with the aim of maintaining the floodgate equipment made up of the gate body 2 and the floodgate opening / closing device 3.

[0011] (Door body 2) The gate body 2 is generally plate-shaped and is arranged to cross the waterway, and is made of, for example, metal. The gate body 2 adjusts the flow of water in the waterway by being raised and lowered by the watergate opening and closing device 3. A plurality of rollers 22 are provided on both end faces of the gate body 2 in the width direction (left and right direction in Figure 1). The plurality of rollers 22 engage with guide rails 23 fixed to both sides of the waterway. As a result, the gate body 2 is supported by the guide rails 23 so that it can move (be raised and lowered) in the height direction (up and down direction in Figure 1) along the guide rails 23.

[0012] A sheave 21 is provided on the upper end surface of the door body 2. The sheave 21 is a movable pulley that rises and falls together with the door body 2. In the example of FIG. 1, one pulley 21 is provided on each side of the upper end surface of the door body 2 in the width direction. The structure of the door body 2 may be changed as desired, for example, the door body 2 may include an upper door and a lower door, which rise and fall in conjunction with each other or individually. For example, in the case where the upper door and the lower door rise and fall individually, the watergate opening and closing device 3 is connected to each of the upper door and the lower door individually.

[0013] (Watergate opening and closing device 3) The water gate opening and closing device 3 is, for example, of a wire rope winch type, and opens and closes the waterway by raising and lowering the gate body 2. The water gate opening and closing device 3 includes an electric motor 31, an electromagnetic brake 32, a hydraulic push-up brake 33, a reducer 34, a transmission shaft 35, two pinion gears (first gears) 36, two drums (rotating machines) 37, two metal wire ropes 38, and two fixing parts 39.

[0014] The electric motor 31 is, for example, an induction motor, and rotates a transmission shaft 35 via an electromagnetic brake 32, a hydraulic push-up brake 33, and a reducer 34. The electric motor 31 is capable of switching the rotation direction of the transmission shaft 35 between forward and reverse rotation.

[0015] The transmission shaft 35 is a rotating shaft that transmits the power of the electric motor 31 to the drum 37. The transmission shaft 35 is connected to the reducer 34 and extends from the reducer 34 to both sides in the width direction. Two pinion gears 36 are fixed to both ends of the transmission shaft 35. The two drums 37 are provided with drum gears (second gears) 371, and each drum gear 371 meshes with one of the two pinion gears 36. The drum 37 also has a gear cover 372 shown by a dashed line in FIG. 1, and the pinion gear 36 and drum gear 371 are covered by the gear cover 372. When the transmission shaft 35 rotates, the two drums 37 rotate forward or backward.

[0016] One end of the wire rope 38 is fixed to each drum 37, and a portion of the wire rope 38 is wound around it. The portion of each wire rope 38 that is not wound around the drum 37 is hung on two pulleys 21 provided on the gate body 2, and a fixing portion 39 is provided at the other end. The fixing portion 39 is fixed to a bank body or the like. For example, when the drum 37 rotates forward, the wire rope 38 is wound around the drum 37, and the gate body 2 rises. On the other hand, when the drum 37 rotates backward, the wire rope 38 is let out from the drum 37, and the gate body 2 descends. Note that the forward and reverse rotations of the drum 37 are for convenience's sake. The winding of the wire rope 38 may be considered to be the reverse rotation of the drum 37, and the letting out of the wire rope 38 may be considered to be the forward rotation of the drum 37.

[0017] The watergate opening and closing device 3 may be provided with a plurality of drums 37 and wire ropes 38 as shown in the example of Fig. 1, but may also be provided with only one combination of drums 37 and wire rope 38. Also, instead of the wire rope 38, a rope other than the wire rope 38, a chain, or the like may be used. Furthermore, the watergate opening and closing device 3 is not limited to a winch-type opening and closing device, but may also be a rack-type opening and closing device that uses a rack, a spindle-type opening and closing device that uses a spindle, or a radial gate-type opening and closing device that rotates an arc-shaped door body, etc.

[0018] The watergate opening and closing device 3 further includes a current sensor (load measuring unit) D1, two vibration sensors (vibration detecting units) D2, and two torque sensors D3. The current sensor D1 detects the drive current of the electric motor 31. The current sensor D1 outputs a current signal (load evaluation value) corresponding to the detected current to the calculation device 4. The current sensor D1 may be connected to a cable or the like in a control panel that controls the electric motor 31.

[0019] The vibration sensor D2 detects vibration of the pinion gear 36. The vibration sensor D2 is installed at a position where it can detect vibration of the pinion gear 36. In the example shown in FIG. 1, one vibration sensor D2 is installed at each bearing of the transmission shaft 35 to which the pinion gear 36 is fixed. The vibration sensor D2 may be installed on a gear cover 372 that covers the pinion gear 36 and the drum gear 371, or on the reducer 34 connected to the transmission shaft 35. The installation direction of the vibration sensor D2, i.e., the orientation of the installed vibration sensor D2, is not particularly limited, and the sensor may be installed in any orientation as long as it can detect vibration of the pinion gear 36. The vibration sensor D2 outputs a vibration signal corresponding to the detected vibration to the calculation device 4.

[0020] The torque sensor D3 detects the torque of the transmission shaft 35. In the example shown in FIG. 1, one torque sensor D3 is installed on the circumferential surface of the transmission shaft 35 near each pinion gear 36. The torque sensor D3 may be, for example, a sensor that measures using a strain gauge, or a sensor that measures the torsional phase at two points on the circumferential surface of the transmission shaft 35. The torque sensor D3 outputs a torque signal to the calculation device 4 according to the detected strain or torsional phase.

[0021] Torque sensor D3, such as a strain gauge, requires time to install on transmission shaft 35 and has a short service life, making it difficult to install it permanently from the perspective of maintenance costs. In the floodgate system 1, torque sensor D3 is used to calculate the approximation formula, which will be described later. For this reason, torque sensor D3 only needs to be installed on transmission shaft 35 when calculating the approximation formula, and does not need to be permanently installed.

[0022] The floodgate opening and closing device 3 may be equipped with sensors other than the current sensor D1, the vibration sensor D2, and the torque sensor D3. The floodgate opening and closing device 3 may be equipped with, for example, an opening meter that measures the opening degree of the gate body 2 by detecting the amount of rotation of the transmission shaft 35, a water level meter that measures the water level by detecting the position of a float floating on the water surface, or a tension sensor that measures the tension of the wire rope 38.

[0023] (Arithmetic unit 4) 2 is a block diagram showing the functional configuration of the arithmetic device 4. As shown in FIG. 2, the arithmetic device 4 includes a signal receiving unit 41, a calculation unit 42, a storage unit 43, and a display unit 44.

[0024] The signal receiving unit 41 receives various signals via a wired or wireless connection. For example, the signal receiving unit 41 receives a current signal from the current sensor D1, a vibration signal from the vibration sensor D2, and a torque signal from the torque sensor D3, and outputs each signal data to the calculation unit 42. The signal receiving unit 41 also outputs each signal data to the storage unit 43, where it is stored as history information.

[0025] The operation unit 42 includes a calculation unit 421 and an estimation unit 422. The calculation unit 421 processes various signals and calculates the damage level (mechanical load) of the water gate equipment during operation. Specifically, the calculation unit 421 calculates the average torque and fluctuating torque of the transmission shaft 35 using an approximation formula, and calculates the damage level based on the operating torque obtained by adding together the average torque and fluctuating torque. Note that the increase in average torque relative to the increase in fluctuating torque is not necessarily constant. For this reason, it is preferable to calculate the average torque separately from the fluctuating torque before calculating the damage level.

[0026] FIG. 3 is a graph showing the relationship between average torque and fluctuating torque and the mechanical load (operating torque). As shown in FIG. 3, the mechanical load during operation, i.e., the damage level, can be calculated based on the operating torque, which is the sum of the average torque and the fluctuating torque. Specifically, the calculation unit 421 calculates the average torque based on the current data using a current-average torque approximation equation that indicates the relationship between the current and the average torque and is stored in advance in the storage unit 43. The calculation unit 421 also calculates the fluctuating torque based on the vibration data using a vibration-fluctuating torque approximation equation that indicates the relationship between the vibration and the fluctuating torque and is stored in advance in the storage unit 43. The calculation unit 421 then calculates the damage level per unit time from the operating torque, which is the sum of the average torque and the fluctuating torque, using the equation that indicates the relationship between the operating torque and the damage level and is stored in advance in the storage unit 43. In addition to the damage degree per unit time, the calculation unit 421 may calculate the damage degree for each operation (run) of the water gate equipment, that is, for each ascent and descent of the gate body 2. This reduces the amount of processing required to calculate the damage degree.

[0027] The current-average torque approximation formula for calculating the average torque and the vibration-fluctuation torque approximation formula for calculating the fluctuation torque are calculated at the initial stage of installation of the floodgate system 1 and are stored in advance in the storage unit 43. The calculation method of these approximation formulas will be described later.

[0028] The estimation unit 422 estimates the remaining lifespan of the floodgate equipment based on the cumulative damage degree obtained by accumulating the damage degree per unit time calculated by the calculation unit 421. Specifically, the estimation unit 422 refers to a relational expression between the cumulative damage degree and the remaining lifespan stored in advance in the memory unit 43, and calculates the remaining lifespan from the cumulative damage degree. The estimation unit 422 outputs the calculated remaining lifespan to the display unit 44 and displays it on the display unit 44. The estimation unit 422 may remotely display the calculated remaining lifespan on a terminal device such as a smartphone or tablet via the Internet, together with or instead of the display unit 44.

[0029] The memory unit 43 stores various information used by the calculation device 4. For example, the memory unit 43 stores a current-average torque approximation equation and a vibration-fluctuation torque approximation equation. These approximation equations are calculated, for example, when the floodgate system 1 is installed and stored in advance in the memory unit 43. The memory unit 43 also stores a relational equation between operating torque and damage level, a relational equation between cumulative damage level and remaining lifespan, and various signal data received by the signal receiving unit 41 while the floodgate system 1 is in operation.

[0030] [Processing of arithmetic unit 4] Next, various processes executed by the calculation device 4 will be described. First, the calculation process of the current-average torque approximation formula and the vibration-fluctuation torque approximation formula will be described. The calculation process of these approximation formulas is executed by the calculation unit 421, for example, at the beginning of installation of the floodgate system 1. However, in consideration of aging deterioration of the floodgate equipment, the calculation process of the approximation formula may be executed every predetermined period of time. Furthermore, both the approximation formula when the gate body 2 is open and the approximation formula when the gate body 2 is closed may be calculated separately. This can further improve the accuracy of estimating the remaining lifespan of the floodgate equipment.

[0031] (Calculation process of current-average torque approximation formula) The calculation unit 421 calculates a current-average torque approximation equation based on the current data detected by the current sensor D1 and the torque data detected by the torque sensor D3.

[0032] Fig. 4 is a graph showing an example of the relationship between current and average torque. As shown in Fig. 4, the relationship between current and average torque is shown by an approximate curve corresponding to the characteristics of electric motor 31. For this reason, calculation unit 421 calculates a current-average torque approximation formula based on current data, torque data, and electric motor rated values ​​(e.g., rated current, rated torque, rated rotation speed, etc.) that are predetermined as characteristics of electric motor 31.

[0033] Specifically, the calculation unit 421 calculates the effective values ​​of the current data detected by the current sensor D1 and the torque data detected by the two torque sensors D3 at regular unit time intervals (for example, approximately 1.0 seconds) and calculates a current-average torque approximation equation corresponding to the rated value of the motor.

[0034] In the approximation curve shown in FIG. 4, when the current obtained from the current data is, for example, 80 A, the calculated average torque is approximately 5000 N·m. By using such a current-average torque approximation formula, the average torque can be calculated based on the current data. Therefore, by detecting the current with the current sensor D1, the average torque can be calculated with high accuracy. The calculation unit 421 stores the calculated current-average torque approximation formula in the storage unit 43.

[0035] The above description is merely an example of a method for calculating an approximation formula for average torque, and the method for calculating the approximation formula for average torque is not limited thereto. Instead of the current data detected by the current sensor D1, the calculation unit 421 may calculate the approximation formula for average torque using, for example, the measured tension of the wire rope 38 measured by the tension sensor (load measurement unit). In this case, the calculation unit 421 may use the measured tension of the wire rope 38 as a load evaluation value for evaluating the load on the electric motor 31 and calculate the average torque from the pulley efficiency, the drum outer diameter, the gear reduction ratio, and the like. For example, if the measured tension of the wire rope 38 is F, the pulley efficiency is η, the diameter of the drum 37 around which the wire rope 38 is wound is D, and the torque of the drum 37 is T, then T = F / η·D / 2. The average torque of the transmission shaft 35 may be calculated by dividing the torque T of the drum 37 by the reduction ratio of the gear reduction stages up to the transmission shaft 35.

[0036] (Calculation process of vibration-fluctuation torque approximation formula) The calculation unit 421 calculates a vibration-fluctuation torque approximation equation based on the vibration data detected by the vibration sensor D2 and the torque data detected by the torque sensor D3.

[0037] The transmission shaft 35 and the drum 37 transmit torque by exerting tangential forces on each other at the meshing portion of the pinion gear 36 and the drum gear 371. When the transmitted torque fluctuates, the fluctuating torque appears as vibrations of the pinion gear 36.

[0038] Here, the vibration data detected by the vibration sensor D2 includes unnecessary information such as electrical noise or vibrations in the surrounding environment. Furthermore, fluctuations in meshing stiffness while the pinion gear 36 and the drum gear 371 are meshing have a significant impact on the torque fluctuations and vibration characteristics when the power of the transmission shaft 35 is transmitted to the drum 37. For this reason, when calculating the vibration-fluctuation torque approximation equation, it is preferable to selectively extract necessary information and eliminate other information.

[0039] Therefore, in the process of calculating the vibration-fluctuation torque approximation equation, the calculation unit 421 selectively extracts the meshing frequency components between the pinion gear 36 and the drum gear 371 based on the meshing ratio between the pinion gear 36 and the drum gear 371. The meshing ratio is a design index indicating the number of meshing teeth, and is a fixed value determined by the shape and dimensions of the gears.

[0040] Specifically, when the meshing ratio between the pinion gear 36 and the drum gear 371 is rounded up to an integer and the resulting number is set to N, the calculation unit 421 calculates a vibration-fluctuation torque approximation equation based on frequency components selected from the first to Nth order components of the meshing frequency components.

[0041] If the meshing ratio between the pinion gear 36 and the drum gear 371 is i, the number of meshing teeth alternates from i to i+1 to i to i+1... For example, if the meshing ratio between the pinion gear 36 and the drum gear 371 is 1.5, the number of meshing teeth alternates from approximately 1 to 2 to 1 to 2... In this case, the calculation unit 421 calculates the vibration-fluctuation torque approximation formula based on frequency components selected from the first-order to second-order components of the meshing frequency components. Furthermore, if the meshing ratio between the pinion gear 36 and the drum gear 371 is 2.5, the number of meshing teeth alternates from approximately 2 to 3 to 2 to 3... In this case, the calculation unit 421 calculates the vibration-fluctuation torque approximation formula based on frequency components selected from the first-order to third-order components of the meshing frequency components. In this way, by selectively extracting the meshing frequency component from the vibration data based on the contact ratio and calculating the vibration-fluctuation torque approximation equation, the calculation accuracy of the fluctuation torque can be improved.

[0042] Fig. 5 is a graph showing an example of the relationship between vibration and torque fluctuation. As shown in Fig. 5, calculation unit 421 may selectively extract the first and second order components of the meshing frequency components and calculate the vibration-torque fluctuation approximation equation based on these first and second order components.

[0043] If the contact ratio is i, then from the beginning to the end of meshing of one tooth, the ratio changes roughly twice: "i meshing → i+1 meshing → i meshing." For this reason, vibrations caused by changes in the number of meshed teeth are generally dominated by the first- and second-order components of the meshing frequency. Therefore, by calculating the vibration-fluctuation torque approximation formula based on the first- and second-order components of the meshing frequency, the calculation accuracy of the fluctuation torque can be ensured while reducing the amount of processing required to calculate the vibration-fluctuation torque approximation formula. However, the vibration-fluctuation torque approximation formula may also be calculated using third- or higher-order components of the meshing frequency. This further improves the calculation accuracy of the fluctuation torque.

[0044] In the example shown in Fig. 5, the calculation unit 421 performs FFT analysis (frequency analysis) on the vibration data detected by the vibration sensor D2 and the torque data detected by the torque sensor D3 at regular unit time intervals (for example, approximately 1.6 seconds when the meshing frequency is 10.8 Hz). The calculation unit 421 then calculates a vibration-fluctuation torque approximation equation for the first-order and second-order components of the meshing frequency (first-order + second-order meshing in Fig. 5) using the least squares method. The unit time (sampling interval) for performing the FFT analysis is set appropriately in consideration of the frequency resolution.

[0045] In the approximate straight line shown in FIG. 5, when the vibration velocity obtained from the vibration data is, for example, 0.8 (mm / s), the calculated fluctuating torque is approximately 430 (N·m). By using this vibration-fluctuating torque approximation formula, it is possible to calculate fluctuating torque based on the vibration data. Therefore, by detecting vibrations with the vibration sensor D2, it is possible to calculate fluctuating torque with high accuracy. The calculation unit 421 stores the calculated vibration-fluctuating torque approximation formula in the storage unit 43.

[0046] [Remaining life estimation process] Next, the remaining lifespan estimation process of the floodgate equipment executed by the calculation unit 421 and the estimation unit 422 of the calculation unit 42 will be described. The remaining lifespan estimation process may be executed at any time while the floodgate equipment is in operation, or may be executed collectively every predetermined period (for example, every day). An example of executing the remaining lifespan estimation process collectively every predetermined period (every day) will be described below.

[0047] Fig. 6 is a flowchart showing an example of a process for estimating the remaining life of a floodgate facility. As shown in Fig. 6, in the floodgate system 1, when the gate body 2 moves, that is, when the gate body 2 rises or falls, the current sensor D1 detects the drive current of the electric motor 31, and the vibration sensor D2 detects the vibration of the pinion gear 36 (step S1, detection step). The detected current and vibration are input to the signal receiving unit 41, which stores the current data and vibration data as history information in the memory unit 43 (step S2). As a result, the current data and vibration data for a predetermined period are accumulated in the memory unit 43.

[0048] Next, after a predetermined period of time has elapsed, the calculation unit 421 executes calculation of the damage level. First, the calculation unit 421 reads out vibration data stored in the storage unit 43 (step S3), and performs FFT analysis on the read out vibration data to extract meshing frequency components based on the meshing ratio between the pinion gear 36 and the drum gear 371 (step S4). At this time, the calculation unit 421 extracts the meshing frequency components used when calculating the vibration-fluctuation torque approximation formula. Then, the calculation unit 421 calculates the fluctuation torque based on the extracted frequency components using the vibration-fluctuation torque approximation formula stored in the storage unit 43 (step S5, calculation step).

[0049] Next, the calculation unit 421 reads out the current data stored in the storage unit 43 (step S6). Then, the calculation unit 421 calculates the effective value of the read out current data, and calculates the average torque using a current-average torque approximation equation stored in advance in the storage unit 43 (step S7).

[0050] Next, the calculation unit 421 calculates the operating torque by adding up the fluctuating torque calculated in step S5 and the average torque calculated in step S7 (step S8).The calculation unit 421 then calculates the damage level per unit time using the relational expression between the operating torque and the damage level and the number of load repetitions per unit time that are pre-stored in the storage unit 43 (step S9).The calculation unit 421 integrates the damage level per unit time per operation of the water gate equipment, that is, each time the gate body 2 is raised and each time the gate body 2 is lowered, to calculate the damage level per operation (step S10).

[0051] The calculation unit 421 repeatedly executes the processes from step S3 to step S10, i.e., the process of calculating the damage degree per operation, until the damage degree for all operations in a predetermined period has been calculated. After calculating the damage degree for all operations, the calculation unit 421 adds the damage degree for all operations to the cumulative damage degree accumulated up to that point, i.e., the cumulative damage degree accumulated up to the previous day (step S11), thereby updating the cumulative damage degree. The calculation unit 421 outputs the updated cumulative damage degree to the estimation unit 422 and stores the updated cumulative damage degree in the memory unit 43.

[0052] Next, the estimation unit 422 estimates the remaining lifespan of the floodgate equipment based on the cumulative damage level output from the calculation unit 421 (step S12). The remaining lifespan of the floodgate equipment can be estimated using a known method such as the cumulative damage rule (Miner's rule).

[0053] Fig. 7 is a graph showing an example of the relationship between the cumulative damage level and the remaining lifespan. For example, if the damage level when the mechanical load Fi per operation is applied ni times is defined as ni / Ni, as shown in Fig. 7, the estimation unit 422 estimates the current remaining lifespan from the approximate straight line of the cumulative fatigue level, assuming that the cumulative fatigue level Σ(ni / Ni) = 1 is the mechanical lifespan.

[0054] In this way, the calculation unit 42 calculates the cumulative damage level based on the fluctuating torque calculated using the vibration-fluctuating torque approximation formula, and estimates the remaining life of the water gate equipment from the cumulative damage level, thereby improving the accuracy of estimating the remaining life.

[0055] The remaining life is estimated for each component of the floodgate equipment. That is, the degree of damage is accumulated for each component, such as the transmission shaft 35, pinion gear 36, and drum 37, and the remaining life of each component is estimated based on the accumulated degree of damage.

[0056] [Summary of Calculation Unit 4] As described above, the calculation device 4 according to this embodiment includes a calculation unit 42 that calculates torque fluctuations of the transmission shaft 35 based on a vibration signal output from the vibration sensor D2 that detects vibrations of the pinion gear 36 fixed to the transmission shaft 35 that transmits the power of the electric motor 31 to the drum 37. If the meshing ratio between the pinion gear 36 and the drum gear 371 that meshes with the pinion gear 36 and transmits the power of the electric motor 31 to the drum 37 is rounded up to an integer, the calculation unit 42 calculates torque fluctuations from the vibration signal using an approximation that indicates the relationship between the torque fluctuations and vibration calculated based on frequency components selected from the first to Nth order components of the meshing frequency components.

[0057] The calculation device 4 calculates the torque fluctuations from the vibration signal using an approximation formula calculated based on frequency components selected from the 1st to Nth order components of the meshing frequency components. Therefore, the calculation device 4 selectively extracts necessary information from the vibration signal to calculate the torque fluctuations, thereby improving the calculation accuracy of the torque fluctuations.

[0058] The application of the arithmetic device 4 according to the present disclosure is not limited to water gate facilities. The arithmetic device 4 can be applied to any equipment having a rotating machine using gears, such as a waste incineration facility or a windmill.

[0059] [Software implementation example] The functions of the arithmetic unit 4 can be realized by a program that causes a computer to function as the unit, and a program that causes a computer to function as each control block of the unit.

[0060] In this case, the device includes a computer having at least one control device (e.g., a processor) and at least one storage device (e.g., a memory) as hardware for executing the program. The control device and storage device execute the program to realize each function described in the embodiment.

[0061] The program may be non-transitory and may be recorded on one or more computer-readable recording media. The recording media may or may not be included in the device. In the latter case, the program may be supplied to the device via any wired or wireless transmission medium.

[0062] In addition, some or all of the functions of each control block can be realized by a logic circuit. For example, an integrated circuit in which a logic circuit that functions as each control block is formed is also included in the scope of the present invention. In addition, the functions of each control block can be realized by, for example, a quantum computer.

[0063] 〔supplement〕 A calculation device according to a first aspect of the present invention includes a calculation unit that calculates the torque fluctuations of a transmission shaft based on a vibration signal output from a vibration detection unit that detects vibrations of a first gear fixed to the transmission shaft that transmits the power of an electric motor to a rotating machine. When the meshing ratio between the first gear and a second gear that meshes with the first gear and transmits the power to the rotating machine is rounded up to an integer, the calculation unit calculates the torque fluctuations from the vibration signal using an approximate equation that shows the relationship between the vibration calculated based on frequency components selected from the first to Nth order components of the meshing frequency components and the torque fluctuations.

[0064] In this configuration, torque fluctuations are calculated from the vibration signal using an approximation formula calculated based on frequency components selected from the 1st to Nth order components of the meshing frequency components. Therefore, this configuration selectively extracts necessary information from the vibration signal to calculate torque fluctuations, thereby improving the accuracy of torque fluctuation calculation.

[0065] In a computing device according to a second aspect of the present invention, in the first aspect, the approximation formula may be calculated based on a first-order component and a second-order component of the meshing frequency components.

[0066] Generally, vibrations caused by changes in the number of meshing teeth are dominated by the first and second order components of the meshing frequency. Therefore, with the above configuration, it is possible to reduce the amount of calculation processing required for the vibration-fluctuation torque approximation equation while ensuring the accuracy of calculation of the fluctuation torque.

[0067] In a calculation device according to aspect 3 of the present invention, in aspect 1 or 2, the calculation unit may calculate the average torque of the transmission shaft based on the load evaluation value output from a load measurement unit that measures the load applied to the electric motor as a load evaluation value and the rated value of the electric motor.

[0068] According to the above configuration, the load applied to the electric motor is measured as the load evaluation value, so that the average torque can be calculated with high accuracy.

[0069] In the calculation device according to aspect 4 of the present invention, in aspect 3, the calculation unit may calculate the damage level based on the sum of the average torque and the fluctuating torque, and estimate the remaining life of the equipment including the rotating machine based on the cumulative value of the calculated damage level.

[0070] In the above configuration, the calculation unit estimates the remaining life of the equipment based on the torque fluctuation calculated using the approximation formula, thereby improving the accuracy of estimating the remaining life.

[0071] A calculation method according to a fifth aspect of the present invention includes a detection step of detecting vibrations of a first gear fixed to a transmission shaft that transmits the power of an electric motor to a rotating machine using a vibration detection unit, and a calculation step of calculating the fluctuation torque of the transmission shaft based on the vibration signal output from the vibration detection unit. When the meshing ratio between the first gear and a second gear that meshes with the first gear and transmits the power to the rotating machine is rounded up to an integer, in the calculation step, the fluctuation torque is calculated from the vibration signal using an approximation formula that shows the relationship between the vibration and the fluctuation torque calculated based on frequency components selected from the first to Nth order components of the meshing frequency components.

[0072] In this method, torque fluctuations are calculated from the vibration signal using an approximation formula calculated based on frequency components selected from the first to Nth order components of the meshing frequency components. Therefore, this method selectively extracts necessary information from the vibration signal to calculate torque fluctuations, thereby improving the accuracy of torque fluctuation calculation.

[0073] The arithmetic device according to each aspect of the present invention may be realized by a computer. In this case, the control program of the arithmetic device that causes the computer to operate as each part (software element) of the arithmetic device to realize the arithmetic device, and the computer-readable recording medium on which the control program is recorded, also fall within the scope of the present invention.

[0074] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in the embodiments are also included in the technical scope of the present invention. [Explanation of symbols]

[0075] 4 Arithmetic unit 31 Electric motor 35 Transmission shaft 36 Pinion gear (first gear) 37 Drum (rotating machine) 42 Arithmetic section 371 Drum gear (second gear) 421 Calculation unit (calculation unit) 422 Estimation unit (calculation unit) D1 Current sensor (load measurement section) D2 Vibration sensor (vibration detection part) S1 Detection step S5 calculation process

Claims

1. a calculation unit that calculates torque fluctuations of a transmission shaft based on a vibration signal output from a vibration detection unit that detects vibrations of a first gear fixed to the transmission shaft that transmits power of the electric motor to a rotary machine, where N is a value obtained by rounding up a contact ratio between the first gear and a second gear that meshes with the first gear and transmits the power to the rotating machine to an integer, the calculation unit calculates the torque fluctuations from the vibration signal using an approximation formula that indicates a relationship between the torque fluctuations and vibrations calculated based on frequency components selected from 1st to Nth order components of meshing frequency components, The calculation unit is a calculation device that calculates the average torque of the transmission shaft based on the load evaluation value output from a load measurement unit that measures the load applied to the electric motor as a load evaluation value and the rated value of the electric motor.

2. The calculation device according to claim 1 , wherein the approximation formula is calculated based on a first-order component and a second-order component of the meshing frequency components.

3. 2. The computing device according to claim 1, wherein the computing unit calculates a damage level based on a value obtained by adding up the average torque and the fluctuating torque, and estimates a remaining life of equipment including the rotating machine based on a cumulative value of the calculated damage level.

4. a detection step of detecting, by a vibration detection unit, vibration of a first gear fixed to a transmission shaft that transmits power of the electric motor to a rotary machine; a calculation step of calculating a torque fluctuation of the transmission shaft based on the vibration signal output from the vibration detection unit, where N is a value obtained by rounding up a contact ratio between the first gear and a second gear that meshes with the first gear and transmits the power to the rotary machine to an integer, in the calculation step, the torque fluctuations are calculated from the vibration signal using an approximation formula that shows a relationship between the vibration and the torque fluctuations, the approximation formula being calculated based on frequency components selected from 1st to Nth order components of meshing frequency components; In the calculation step, the average torque of the transmission shaft is calculated based on a load evaluation value obtained by measuring the load applied to the electric motor and a rated value of the electric motor.

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