METHOD FOR MONITORING A GEARBOX MOTOR AND SYSTEM

Description

[0001] The invention relates to a method for monitoring a geared motor and a system.

[0002] It is well known that the speed of the rotor shaft of an electric motor can be measured.

[0003] A modular data collection system is known from US 6 434 512 B1.

[0004] EP 1 217 261 A2 discloses an optimization of the time intervals for oil changes in a transmission.

[0005] From DE 10 2011 121 272 A1 a method for temperature-dependent control of an electric motor is known.

[0006] A system with a gearbox is known from DE 10 2008 013 059 A1.

[0007] From the US 6 425 293 B1 The closest state of the art is a sensor connector.

[0008] From the KR 102 074 161 B1 is an electrical device with a Bluetooth connection.

[0009] From the US 10 608 564 B1 is a universal monitor and error detection system.

[0010] The invention is therefore based on the object of designing a drive that is flexibly adaptable while ensuring a high level of safety.

[0011] According to the invention, the object is achieved by the method according to the features specified in claim 1 and by the system according to claim 6.

[0012] Important features of the method for monitoring a geared motor are that the geared motor has a gear that is at least partially filled with oil, wherein a measure of the oil level, in particular a measure of the fill level of the oil, is detected and a measure of vibration is detected at at least one point of the transmission, wherein a first variable is formed by linking the measure of the oil level and the measure of vibration, the value of the first variable is monitored for exceeding a permissible degree of deviation from a target value or for exceeding a threshold value.

[0013] The advantage here is that the linked variables change their signals when the oil level drops.

[0014] In an advantageous embodiment, if the limit is exceeded, a warning message is displayed and / or transmitted and / or an emergency shutdown of the electric motor powered by an inverter that drives the transmission is triggered, or a safe state is activated for the electric motor powered by an inverter that drives the transmission. The advantage here is that increased safety can be achieved.

[0015] According to the invention The link involves a division, with the first value being calculated as the quotient of the vibration measure and the oil level measure. The advantage here is that a simple mathematical operation is sufficient to increase sensitivity.

[0016] According to the invention alternativelyThe link involves a division, where the first value is calculated as the quotient of the vibration measure, a transmission temperature measure, and the oil level measure. The advantage of this is that high sensitivity can be achieved through simple mathematical operations, thus enabling efficient monitoring.

[0017] In an advantageous embodiment, the vibration measure is an average of the Fourier-transformed time profile of the vibration measure, particularly in a frequency band. This is advantageous because a frequency in the frequency band generated by a bearing makes a significant contribution to the measure if the bearing has deteriorated lubrication.

[0018] Important features of the invention in the system for carrying out an aforementioned method are that the system has a gear driven by an inverter-fed electric motor and has a modular evaluation unit, wherein the evaluation unit has evaluation modules, a central module and a supply module.

[0019] The advantage here is that a modular design of the evaluation unit allows for the addition of further evaluation units and thus additional sensors via these evaluation units, so that the central module is capable of performing improved evaluations. The number of evaluation units and therefore also sensors can be adapted to the respective drive task. This allows for flexible cost and effort adjustment. For example, a sensor for recording the torque output at the output shaft and / or the speed output at the output shaft can be recorded and transferred to the central module. The central module is connected not only to a display for displaying warning information but also to a controller that controls the inverter feeding the electric motor.This also increases safety, as a sensor can be easily added, allowing the central module to carry out improved monitoring of the transmission, in particular improved condition monitoring.

[0020] In an advantageous embodiment, the evaluation modules, the central module, and the supply module are arranged in a row. This is advantageous because the modules can be arranged in a single row, one behind the other, thus allowing for a clear layout of the evaluation unit. Furthermore, an additional evaluation module can be easily added at the end without having to modify the hardware of the remaining evaluation unit.

[0021] In an advantageous embodiment, the evaluation modules and the central module are electrically supplied in parallel from the supply module. This is advantageous in that a DC voltage supply to the evaluation modules and the central module can be implemented from a supply module fed by an AC voltage supply network. The supply module comprises a rectifier and, in particular, a smoothing capacitor. Preferably, the DC voltage supply is looped through the evaluation modules, and the evaluation modules, which are arranged in series and touching one another, are connected via electrical plug connections.

[0022] In an advantageous embodiment, each sensor arranged on the transmission is electrically connected to a uniquely assigned evaluation module. This is advantageous because the sensor signals can be individually processed. In particular, low-pass filtering of the sensor signal, amplification, and / or offset voltage can be applied or added. Furthermore, an analog signal can be converted into a digital data stream, which is fed to the central module.

[0023] In an advantageous embodiment, each evaluation module has its own housing. This has the advantage that signal processing within each module can be carried out without interference from other modules.

[0024] In an advantageous embodiment, each evaluation module is connected to the central module via a wireless or wired data transmission channel. This is advantageous because the data acquired and processed by the sensor can be transmitted to the central module. This allows the signals from different sensors to be linked together, and the result of the linking can be used to detect an unacceptably high degree of deviation from a setpoint or setpoint range, particularly for condition monitoring.

[0025] In an advantageous embodiment, the central module has a means for linking sensor signals, the result of which is fed to a monitoring means connected to a means for displaying warning information and / or to a means for shutting down the electric motor. This is advantageous because improved monitoring can be achieved. Simply monitoring the values ​​of a single variable for exceedance of a threshold can lead to errors, as fluctuations, particularly in the range of the threshold, can distort the monitoring. According to the invention, however, several variables are linked, thus forming a more sensitive combined variable.

[0026] In an advantageous embodiment, a first sensor is designed to detect the oil level, in particular to detect the fill level of the oil present in the transmission. The advantage here is that the fill level is monitored and can be linked to other variables. This allows for the creation of a linked combination variable, to which the signals from another sensor can be fed, which also generates modified signals as the oil level drops. For example, the structure-borne sound amplitudes averaged in a frequency band increase.

[0027] In an advantageous embodiment, a second sensor is designed to detect transmission vibration. This is advantageous because the structure-borne sound amplitudes of the transmission, particularly in the vicinity of a transmission bearing, can be determined and linked to sensor signals from additional sensors.

[0028] In an advantageous embodiment, a third sensor is suitably designed to detect the temperature of the transmission, in particular wherein the third sensor is an infrared sensor and / or wherein the third sensor is arranged within a housing part of the transmission. Advantageously, the signals from a third sensor can be linked to the other two, thus allowing the determination of different physical variables that change their signals when the oil level drops.

[0029] Further advantages emerge from the dependent claims. The invention is not limited to the combination of features in the claims. Further possible combinations of claims and / or individual claim features and / or features of the description and / or the figures will become apparent to those skilled in the art, particularly from the problem and / or the problem posed by comparison with the prior art.

[0030] The invention will now be explained in more detail with the aid of schematic illustrations: In the Figure 1 A transmission system according to the invention is schematically sketched.

[0031] The gearbox has a housing part 1 in which bearings are accommodated for supporting shafts to which gear parts are connected in a rotationally fixed manner.

[0032] The input shaft 2, in particular the driving, in particular the input, shaft, is connected to the rotor shaft of an electric motor in a rotationally fixed manner or via a coupling.

[0033] The output shaft 6 can be connected to a load to be driven.

[0034] Sensors are arranged on or in the housing part 1, in particular an oil level sensor 3 for detecting the oil level surrounded by the housing part 1, a temperature sensor 4 for detecting the temperature within the housing part and a vibration sensor 5, in particular a structure-borne sound sensor, for detecting the mechanical, in particular acoustic, vibrations of the housing part 1.

[0035] The signals from the sensors are sent to a Figure 1 fed to a modular evaluation unit (not shown).

[0036] The evaluation unit comprises evaluation modules, a central module, and a power supply module arranged in series. The evaluation modules and the central module are electrically supplied in parallel from the power supply module.

[0037] The sensor signal of the oil level sensor 3 is fed to a first of the evaluation modules, the sensor signal of the temperature sensor 4 is fed to a second of the evaluation modules and the sensor signal of the vibration sensor 5 is fed to a third of the evaluation modules.

[0038] The central module is connected to the evaluation modules via a data transmission channel.

[0039] In the central module, the measured values ​​recorded and determined by the sensors and evaluation modules are evaluated, whereby condition monitoring is carried out.

[0040] The central module monitors the measured values ​​in such a way that if a permissible deviation from a specified range is exceeded, a warning signal and / or a shutdown signal is issued.

[0041] The shutdown signal either shuts down the motor, particularly via an inverter supplying the motor, or activates a safe state of the electric motor. This does not necessarily have to be a standstill of the rotor shaft, but can also be a smooth, preferably even, rotation of the motor's rotor shaft.

[0042] In the central module, the measured values ​​determined by the evaluation modules are linked together and monitoring is carried out depending on this.

[0043] For example, a first variable can be formed which comprises the quotient of a product and the detected level value of the oil level, wherein the product is formed from the detected temperature and a value determined from the vibration values ​​detected by means of the vibration sensor.

[0044] For example, the amplitude of a filtered frequency or the average amplitude of a frequency band is used as the value determined from the vibration values ​​detected by the vibration sensor. Preferably, the signal from the vibration sensor 5 is fed to an FFT, and a measure of the average amplitude and / or the integral of the amplitudes as a function of frequency is formed from the thus determined Fourier spectrum for a frequency band.

[0045] For example, if the oil level drops and thus the lubrication of the bearings and / or the meshing gear parts deteriorates, the value determined from the vibration values ​​recorded by the vibration sensor and also the friction of the meshing parts increase.

[0046] Due to the resulting linkage, particularly the quotient and product formation, the first variable reacts extremely strongly. A slight drop in the oil level can lead to a slight increase in vibration and temperature. However, multiplication and division result in a significant change in the value of the first variable. Thus, a high degree of sensitivity to change is achieved.

[0047] In further education, mathematically similar qualitatively similar relationships can also be used.

[0048] Furthermore, the motor current can be measured using a sensor for detecting the electric motor's motor current, and the sensor signals can be fed to another evaluation module. From there, specific values ​​are sent to the central module, which links these values ​​determined from the measured motor current with values ​​from other sensors, so that the result of the linking is monitored for an unacceptably large deviation from a permissible value.

[0049] In further embodiments according to the invention, the RMS value, in particular the root mean square value, of the Fourier-transformed value curve detected by the vibration sensor 5 is calculated, particularly in a frequency band. From this, the quotient of this RMS value and the value determined from the signal of the oil level sensor 3 is calculated and monitored for an unacceptably high degree of deviation from a threshold value. Thus, a variable that reacts very sensitively to changes caused by deterioration in lubrication is accessible for monitoring. List of reference symbols

[0050] 1Housing part 2Input shaft, in particular driving shaft 3Oil level sensor 4Temperature sensor 5Vibration sensor, in particular structure-borne sound sensor 6Output shaft

Claims

1. Method for monitoring a gear motor, the gear motor comprising a gearbox that is at least partly filled with oil, a measure for the oil level, in particular a measure for the fill level of the oil, being registered, and a measure for vibration at least at one location on the gearbox being registered, a first variable being generated by interlinking the measure for the oil level and the measure for vibration, characterised in that the value of the first variable is monitored for exceeding a permitted level of deviation from a target value or for exceeding a threshold value, the interlinking comprising a division, - the first variable being generated as a ratio of the measure for vibration and the measure for the oil level, - or the first variable being generated as a ratio of a product, which is generated from the measure for vibration and a measure for the temperature of the gearbox, and the measure for the oil level.

2. Method according to claim 1, characterised in that in the event of an overshoot, warning information is displayed and / or relayed, and / or an emergency shutdown of the electric motor, which is fed by an inverter and drives the gearbox, is brought about, or the activation of a safe state of the electric motor that is fed by an inverter and drives the gearbox is brought about.

3. Method according to any of the preceding claims, characterised in that the measure for vibration is an average of the Fourier-transformed time curve of the measure for vibration, in particular in one frequency band.

4. System, the system comprising a gearbox driven by an inverter-fed electric motor, and comprising an evaluation unit configured in a modular manner, the evaluation unit having evaluation modules, a central module and a power supply module, characterised in that the central module is configured and suitable for carrying out a method according to any of the preceding claims.

5. System according to claim 4, characterised in that the evaluation modules, the central module and the power supply module are arranged side by side.

6. System according to any of claims 4 to 5, characterised in that the evaluation modules and the central module are powered from the power supply module electrically in parallel.

7. System according to any of claims 4 to 6, characterised in that each sensor (3, 4, 5) arranged on the gearbox is electrically connected to a respective evaluation module unambiguously assigned to that sensor.

8. System according to any of claims 4 to 7, characterised in that each evaluation module has its own housing.

9. System according to any of claims 4 to 8, characterised in that each evaluation module is connected to the central module by means of a wireless or wired data transmission channel.

10. System according to any of claims 4 to 9, characterised in that the central module comprises a means for interlinking sensor signals, the result of which is supplied to a monitoring means that is connected to a means for displaying warning information and / or to a means for shutting the electric motor down.

11. System according to any of claims 4 to 10, characterised in that a first sensor (3) is configured to be suitable for registering the oil level, in particular for registering the fill level of the oil present in the gearbox.

12. System according to any of claims 4 to 11, characterised in that a second sensor (5) is configured to be suitable for registering the vibration of the gearbox.

13. System according to any of claims 4 to 12, characterised in that a third sensor (4) is configured to be suitable for registering the temperature of the gearbox, the third sensor in particular being an infrared sensor, and / or in that the third sensor is arranged inside a housing part of the gearbox.