Automatic lubrication system for a bearing and method for operating an automatic lubrication system

Abstract

Automatic lubrication system (1) for automatically and on-demand supplying lubricant to a bearing (2), comprising an automatic lubrication device (3) for automatically supplying lubricant to the bearing (2) and a detection device (4) for detecting operating parameters of the bearing (2), characterized in that the lubrication system (1) comprises a data transmission device (5) configured for transmitting data between the detection device (4) and the lubrication device (3), wherein the detection device (4) is configured for detecting at least one operating vibration (B) and a rotational speed of the bearing (2), wherein the lubrication system (1) comprises an evaluation device configured to evaluate the detected operating vibration (B) as a function of the rotational speed in order to determine whether the bearing (2) has sufficient lubricant, wherein the evaluation device is configured to determinewhich part of the operating vibration (B) of the bearing (2) is due to a lubrication condition of the bearing (2) and which part of the operating vibration (B) of the bearing (2) is due to external influences, and wherein the automatic lubrication device (3) is configured to supply the bearing (2) with lubricant depending on the operating parameters detected by the detection device (4).

Description

[0001] The invention relates to an automatic lubrication system for the automatic and demand-controlled supply of lubricant to a bearing, comprising an automatic lubrication device for the automatic supply of lubricant to the bearing and a detection device for recording operating parameters of the bearing.

[0002] Lubricants, such as bearing oils or greases, are used to reduce the internal resistance of a bearing caused by friction, such as static or sliding friction. In rolling bearings, where a first bearing part is movable relative to a second bearing part via rolling elements, the lubricant is needed to reduce the internal resistance, particularly in the area of ​​the rolling elements and the raceways for the rolling elements. Appropriate seals are provided to prevent the lubricants from escaping the rolling bearing, especially during operation.

[0003] The service life of lubricants is often limited and can depend on various factors, including the operating parameters of the rolling bearing, such as operating temperature, speed, bearing pressure, and surrounding media like gases (e.g., oxygen), solids (e.g., salts), or liquids (e.g., water). Furthermore, even with a bearing seal, lubricant can sometimes escape. Therefore, the lubricating effect of a bearing lubricant decreases with increasing operating time. As a result, the internal resistance or friction of the bearing increases, leading to increased bearing wear. Consequently, to prevent excessive bearing wear and ensure the lowest possible internal resistance, it is crucial to avoid operating the bearing with insufficient or inadequate lubricant.

[0004] To ensure that the bearing is adequately lubricated, many bearings have connections for lubricant pumps, such as grease nipples. Fresh lubricant can be forced into the bearing's interior via these grease nipples, for example, using a lubricant pump. It may also be designed to allow old or used lubricant, whose tribological properties are impaired, for example, by the absorption of bearing abrasion particles, to be displaced from the bearing in this way.

[0005] Especially in large bearings subjected to high mechanical loads, an adequate supply of lubricant is crucial, as such bearings are often integral parts of large systems, such as wind turbines, and their failure can result in significant costs. For example, the downtime of a wind turbine incurs costs for the operator for the duration of the outage, as the turbine does not generate electricity. Furthermore, replacing such a bearing is a complex and costly process, since the components of a wind turbine can sometimes weigh several tons. Disassembly and subsequent assembly of the bearing is therefore only possible using specialized equipment and is thus very expensive. For this reason, insufficient lubrication of such bearings must be avoided.

[0006] To ensure a regular supply of lubricant to the bearing, automatic lubrication systems are known that supply the bearing with lubricant according to a predetermined maintenance schedule. All such lubrication systems have the disadvantage that they do not detect the actual lubricant requirement and can only provide lubricant based on empirical data or calculations. Special operating conditions, such as lubricant leakage, contamination of the lubricant (e.g., through abrasion of bearing components), increased lubricant requirement due to specific bearing loads, or resinification of the lubricant, are not taken into account by these lubrication systems. Consequently, with such lubrication systems, the bearing may, for example, be undersupplied with lubricant, which increases bearing wear. In the worst case, this can lead to bearing damage.An overestimation of the bearing's lubricant requirements can also lead to an oversupply of lubricant. Such a situation is also disadvantageous, as it may impair the bearing's functionality.

[0007] Systems for lubricating or relubricating bearings, such as rolling bearings, are known from the prior art, such as DE 10 2005 057 610 A1, DE 10 2014 204 062 A1, DE 694 33 065 T2, DE 11 2010 003 390 T5 or US 2013 / 0 015 019 A1.

[0008] DE 10 2013 203 263 A1 discloses a device for supplying lubricant to a lubrication point in a machine. The device comprises a lubricant pump unit and a control unit. The lubricant pump unit is designed to supply lubricant to a lubrication point. Furthermore, the control unit is designed to regulate the quantity of lubricant supplied to the lubrication point by the lubricant pump unit based on a sensor measurement signal. The sensor measurement signal depends on a temperature measured in a region of the lubrication point, a pressure measured in a region of the lubrication point, a viscosity measured in a region of the lubrication point, a dielectric constant measured in a region of the lubrication point, a water content measured in a region of the lubricant, a vibration intensity measured at a part of the machine, or a rotational speed measured at a part of the machine.

[0009] DE 11 2013 004 129 T5 discloses a system with a sensor configured to be arranged in a container of a machine having moving parts lubricated by a liquid in the container. The sensor is configured to obtain a measurement of the liquid that identifies at least a quantity and / or quality of the liquid in the container. The system further comprises a device base that is operationally connected to the sensor. The device base includes a processor unit that is operationally connected to the sensor and configured to generate initial data signals that identify the measurement of the liquid. The device base also includes a transmitter configured to wirelessly transmit the initial data signals to a remotely located reader.

[0010] JP 2008-131 713 A discloses a lubrication device for a rotating machine, wherein a vibration value is detected and the amount of lubricating oil in a bearing is adjusted when the vibration value exceeds a threshold.

[0011] The object of the present invention is therefore to provide an automatic lubrication system for automatically supplying a bearing with lubricant, which at least partially avoids the disadvantages mentioned above. In particular, it is the object of the present invention to provide an automatic lubrication system for automatically and on-demand supplying a bearing with lubricant, which ensures, at least substantially, that the bearing is supplied with lubricant in accordance with its actual lubrication requirements.

[0012] This problem is solved by an automatic lubrication system for the automatic and demand-controlled application of lubricant to a bearing according to claim 1. Dependent claims 2 to 5 relate to particularly preferred embodiments of the automatic lubrication system.

[0013] Accordingly, the object of the present invention is achieved by an automatic lubrication system for the automatic and demand-controlled supply of lubricant to a bearing, comprising an automatic lubrication device for automatically supplying lubricant to the bearing and a detection device for acquiring operating parameters of the bearing. The lubrication system includes a data transmission device designed for transmitting data between the detection device and the lubrication device. The automatic lubrication device is configured to supply lubricant to the bearing depending on the operating parameters detected by the detection device.

[0014] An automatic lubrication system, for example, comprises a lubricant pump, a lubricant tank, a lubricant line, and a control unit. The control unit is designed to control the lubricant pump in such a way that it delivers lubricant from the lubricant tank through the lubricant line into the bearing.

[0015] The detection device has at least one sensor designed to detect at least one operating parameter of the bearing. Examples of bearing operating parameters include bearing speed, bearing temperature, bearing vibration, or bearing pressure. These operating parameters can be determined during bearing operation and may depend on the type of bearing operation. Bearing vibrations, for example, depend on the bearing speed and the supply of lubricant to the bearing. Preferably, the detection device has one or more sensors for detecting multiple operating parameters of the bearing. Furthermore, the detection device is designed to provide data based on the detected operating parameters to the data transmission device. This data can include, for example, raw data of the detected operating parameters, evaluated operating parameter data, or control signals for the lubrication system to supply the bearing with lubricant.

[0016] The data transmission device is designed to transmit the data generated by the detection device to the lubrication device. Thus, the data transmission device enables the lubrication device to be controlled based on the detected operating parameters of the bearing.

[0017] Information about the current lubricant supply to the bearing can be determined from its operating parameters. For example, bearing characteristic curves can be used to analyze the current lubricant condition and / or requirement. The automatic lubrication system is preferably designed to evaluate operating parameters using a Fourier transform. For example, the frequency spectrum of an acoustic sensor or an acceleration or vibration sensor can indicate whether there is predominantly metallic contact between the rolling elements and raceways in the bearing, or whether such contact is prevented by sufficient lubrication.

[0018] This type of lubrication system offers an advantage over conventional systems for automatically supplying lubricant to a bearing: Lubrication is no longer limited to predefined intervals, but can occur based on the bearing's actual lubrication needs. For example, by analyzing the bearing's operating parameters, it's possible to determine when a critical lubrication condition, such as insufficient lubricant supply, is imminent if relubrication is not performed in a timely manner. To prevent such a critical lubrication condition, the lubrication system can automatically relubricate the bearing in a timely manner. A further advantage is that no lubricant is wasted, as lubrication is applied on demand rather than according to a fixed lubrication schedule.Naturally, the lubrication system is suitable for ensuring the supply of lubricant to the bearing both according to a defined lubrication schedule and as needed, depending on the operating parameters of the bearing.

[0019] According to a preferred embodiment of the lubrication system, the detection device and the lubrication device are galvanically isolated from each other. This is particularly advantageous in large installations, such as wind turbines, since the lubrication device and the detection device can interfere with or damage each other, for example, due to differing electrical potentials or ground currents. Galvanic isolation of the detection device and the lubrication device prevents such interference and thus increases the operational reliability of the lubrication system.

[0020] Preferably, the data transmission device is designed for transmitting optical signals. For this purpose, the data transmission device includes, for example, a transmitter for emitting light waves and a receiver for receiving the light waves. For transmitting the light waves, the data transmission device preferably includes an optical fiber, such as a fiber optic cable. Optical signals have the advantage that data can be transmitted without a galvanic connection between the transmitter and receiver.

[0021] The data transmission device preferably includes a relay for transmitting electrical signals. Electrical signals from a primary circuit can be transmitted to a secondary circuit via the relay without establishing a galvanic connection between the two. The primary circuit is preferably coupled to the sensing device and the electromagnet of the relay. The secondary circuit is preferably interruptible or closed by the relay and coupled to the lubrication device. By applying a data pulse to the primary circuit, the relay can be actuated such that the data pulse can be transmitted to the secondary circuit via the relay. Thus, data transmission from the sensing device to the lubrication device is possible without galvanic coupling between the two, using simple, cost-effective, and reliable means.

[0022] In an advantageous embodiment of the lubrication system, the data transmission device comprises at least one radio transmitter and at least one radio receiver for transmitting radio signals. The radio transmitter is preferably coupled to the detection device, and the radio receiver is coupled to the lubrication device. Thus, data can be transmitted from the detection device to the lubrication device without requiring a galvanic connection between the two. Such a data transmission device has the further advantage that data from the detection device and, if applicable, from the lubrication device can be transmitted to a remote control unit. Operating states of the lubrication system can therefore be monitored easily and cost-effectively.

[0023] Preferably, the detection device is designed to detect accelerations and / or velocities. Detectable accelerations include, for example, vibrations, particularly those caused by the bearing during operation. Using suitable analysis methods, such as Fourier transformation, conclusions about the bearing's lubrication condition can be derived from the measured accelerations. In particular, an evaluation of the spectrum of recorded accelerations can reliably provide insights into the tribological condition of the bearing and, if necessary, indicate the need for relubrication. A velocity is, for example, the rotational speed of the bearing.

[0024] The detection device is particularly well-suited for recording accelerations and velocities. This allows for the additional consideration of the relationship between bearing vibrations and bearing load. This has the advantage of enabling the determination of what portion of the bearing vibrations is attributable to the bearing's lubrication condition and what portion is due to external influences, such as the current bearing load. This significantly improves the accuracy and reliability of the lubrication system. For example, in many applications, including wind turbines, the current bearing load can directly correspond to the current bearing speed.This can lead, for example, to a situation where, with one and the same detected operating vibration, the evaluation at a first speed of the bearing shows that the bearing has sufficient lubricant, while the evaluation at a second, lower speed of the bearing shows that the bearing does not have sufficient lubricant.

[0025] The lubrication system is particularly well-suited for lubricating a bearing in a wind turbine. Wind turbine bearings, especially rotor bearings, are subjected to high loads during operation and therefore require optimal lubrication, which is ensured by the lubrication system. Furthermore, the lubrication systems of such bearings are also subject to particularly high loads, making lubrication systems with galvanic isolation between the detection device and the lubrication device especially suitable for this application.

[0026] Furthermore, the problem is solved by a method for operating an automatic lubrication system to lubricate a bearing. The method comprises the following steps: - Detecting at least one operating vibration of a bearing; - Evaluating the detected operating vibration to determine whether the bearing has sufficient lubrication; and - Automatic lubrication of the bearing if the bearing does not have sufficient lubricant.

[0027] The bearing generates operating vibrations. These vibrations depend, among other things, on the bearing's lubrication condition. For example, by comparing the operating vibrations with target values, the bearing's current lubrication condition can be determined. Particularly strong vibrations or high amplitudes of the operating vibrations indicate a lubrication condition that requires relubrication, while vibrations with relatively low amplitudes indicate that sufficient lubricant is still present. The frequency spectrum of the vibrations can also provide information about the bearing's tribological condition. If relubrication is necessary, a defined quantity of lubricant is preferably added to the bearing.Preferably, the defined quantity depends on the determined lubricant condition, so that if a particularly high lubricant requirement is identified, a correspondingly high quantity of lubricant is delivered to the bearing. Alternatively, the defined quantity of lubricant is predefined, so that the same quantity of lubricant is delivered to the bearing with each delivery.

[0028] The bearing is thus automatically and on demand lubricated when a lubrication condition is detected that requires relubrication. Preferably, the method is implemented such that this lubrication condition is only detected when characteristic operating vibrations have a predefined duration, e.g., one minute, or frequency, e.g., 2 to 10 times, in order to avoid spontaneous lubrication due to, for example, a single strong operating vibration.

[0029] The automatic lubrication of the bearing is particularly advantageous if at least a predefined minimum time interval elapses between two lubrication processes. This interval is preferably between 1 and 250 hours, more preferably between 5 and 50 hours, and most preferably around 24 hours. This is advantageous because the lubricant supplied to the bearing must first distribute itself within the bearing, and significant operating vibrations can still occur during this period. This prevents over-lubrication of the bearing. It also has the advantage of reducing lubricant consumption.

[0030] The method is particularly preferably carried out on a lubricant system according to the invention. A lubricant system according to the invention is particularly suitable for carrying out the method.

[0031] In an advantageous embodiment of the method, the detected operating vibration is evaluated as a function of the bearing's rotational speed. Operating vibrations, and in particular their amplitude, of a bearing depend on the lubricant condition and the bearing's rotational speed. By taking the rotational speed dependence of the measured operating vibrations into account, the lubricant condition can be determined even more precisely. This further improves the method.

[0032] Furthermore, it is preferable to consider a bearing temperature and / or a bearing pressure when evaluating the detected operating vibration, since the operating vibrations of the bearing may also be dependent on these parameters.

[0033] Preferably, the detected operating oscillation is evaluated using a fast Fourier transform. Such an algorithm has proven particularly suitable for evaluating operating oscillations.

[0034] Features described in connection with the automatic lubrication system for the automatic and demand-controlled application of lubricant to a bearing are also considered to be disclosed in connection with the method for operating an automatic lubrication system for lubricating a bearing, and vice versa, so that mutual reference can be made to these features.

[0035] The invention will now be explained in more detail with reference to a drawing. The drawing schematically illustrates: Fig. 1 a first embodiment of the automatic lubrication system, Fig. 2. A diagram of the vibration intensity of an operating vibration as a function of time, Fig. 3 A flowchart of the procedure for operating an automatic lubrication system for lubricating a bearing.

[0036] The in Fig. Figure 1, a schematically depicted first embodiment of the automatic lubrication system 1 for the automatic and demand-based supply of lubricant to a bearing 2, comprises a lubrication device 3. This device optionally includes a lubricant tank 13 and a lubricant pump 12. The lubrication device 3 is designed to supply the bearing 2, such as a rotor bearing of a wind turbine, with lubricant, such as grease. The lubrication system 1 includes a detection device 4 for detecting operating conditions of the bearing 2. The detection device 4 can optionally include, for example, an acceleration sensor 7 for detecting or measuring operating vibrations B (see Figure 1). Fig. 2) of the bearing 2. Furthermore, the detection device 4 can optionally include a speed sensor 8 for detecting or measuring the bearing speed of the bearing 2. The speed sensor 8 is, for example, an optical speed sensor 8. The detection device 4 can optionally include a control unit 6, which is configured to evaluate the operating parameters of the bearing 2 detected by the acceleration sensor 7 and the speed sensor 8. The control unit 6 is further configured to generate a control signal for controlling the lubricant pump 12 based on the evaluated operating parameters. By means of the control signal, the lubricant pump 12 can be switched on to pump lubricant into the bearing 2 and switched off to interrupt the pumping of lubricant.

[0037] To transmit the control signal from the detection device 4 to the lubrication device 3, the lubrication system 1 has a data transmission device 5. This device can, for example, include an optical transmitter 9, an optical conductor 10, and an optical receiver 11. The optical transmitter 9 is coupled to the detection device 4 and is configured to send the control signal to the optical receiver 11 via the optical conductor 10. The optical receiver 11 is coupled to the lubrication device 3 and is configured to receive the control signal. The lubrication device 3 and the detection device 4 are thus galvanically isolated from each other.

[0038] Fig. Figure 2 shows a diagram depicting the vibration amplitude of an operating vibration B as a function of time in arbitrary units. This diagram is speed-corrected, so that any variation in the vibration amplitude of the operating vibration B caused by a bearing speed of bearing 2 is already compensated for in the depicted operating vibration B. Before a first time t1, the operating vibration B is within a normal range, in which the bearing 2 has sufficient lubrication. From time t1 onwards, the vibration amplitude of the operating vibration B exceeds a critical vibration amplitude S. krit As can be seen from this diagram, the vibration intensity of the operating vibration B exceeds the critical vibration intensity S even after time t1. kritFrom this, it can be concluded that there is a need for lubricant, so the lubricant system 1 supplies lubricant to the bearing 2. From time t2 onwards, the operating vibration B is again below the critical vibration intensity S. krit This reflects the effects of the lubricant being delivered to bearing 2 by the lubrication system 1.

[0039] In Fig.Figure 3 describes the method for operating an automatic lubrication system 1 for lubricating a bearing 2. In a first process step 100, at least one operating vibration B of the bearing 2 is determined using a vibration sensor 7, and a bearing speed of the bearing 2 is determined using a speed sensor 8. In a second process step 200, the determined operating vibration B is evaluated based on characteristics of the bearing 2 as a function of the determined bearing speeds. This determines whether the bearing 2 has sufficient lubricant. In a third process step 300, a control command is transmitted to a lubrication device 3 of the lubrication system 1 to control the lubrication device 3 if it is determined that the bearing 2 does not have sufficient lubricant. The control command causes the lubrication device 3 to lubricate the bearing 2. Reference symbol list 1 Lubrication system 2 warehouses 3 Lubrication device 4 Detection device 5 Data transmission device 6 Control unit 7 Accelerometer 8 Speed ​​sensor 9 optical transmitters 10 optical ladder 11 optical receivers 12 Lubricant pump 13 Lubricant tank 14 Lubricant line 100 first procedural step 200 second procedural step 300 third procedural step B Operating oscillation S krit Critical vibration intensity t1 first time point t2 second time point

Claims

[1] Automatic lubrication system (1) for automatically and on demand supplying a bearing (2) with lubricant, comprising an automatic lubrication device (3) for automatically supplying the bearing (2) with lubricant and a detection device (4) for detecting operating parameters of the bearing (2), characterized bythat the lubrication system (1) comprises a data transmission device (5) configured for transmitting data between the detection device (4) and the lubrication device (3), wherein the detection device (4) is configured for detecting at least one operating vibration (B) and a rotational speed of the bearing (2), wherein the lubrication system (1) comprises an evaluation device configured to evaluate the detected operating vibration (B) as a function of the rotational speed in order to determine whether the bearing (2) has sufficient lubricant, wherein the evaluation device is configured to determine which part of the operating vibration (B) of the bearing (2) is attributable to a lubricant condition of the bearing (2) and which part of the operating vibration (B) of the bearing (2) is attributable to external influences, and wherein the automatic lubrication device (3) is configuredto apply lubricant to the bearing (2) depending on the operating parameters detected by the detection device (4). [2] Lubrication system (1) according to claim 1, characterized by , that the data transmission device (5) galvanically isolates the detection device (4) and the lubrication device (3) from each other. [3] Lubrication system (1) according to claim 1 or 2, characterized by , that the data transmission device (5) is designed to transmit optical signals, has a relay for transmitting electrical signals, or has at least one radio transmitter and at least one radio receiver for transmitting radio signals. [4] Lubrication system (1) according to any one of the preceding claims, characterized by , that the detection device (4) is designed to detect accelerations, in particular vibrations, and / or velocities, in particular rotational speed. [5] Lubrication system (1) according to any one of the preceding claims, characterized by , that the lubrication system (1) is designed to lubricate a bearing (2) of a wind turbine.

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