Bearing wear monitoring

Abstract

The described aspects and embodiments relate to a bearing wear monitoring device configured to monitor bearings of a vacuum pump having an electric motor with a rotating assembly. The monitoring device comprises an input receiving circuit configured to receive a signal indicative of a rotation characteristic of the rotating assembly, and a bearing wear monitoring circuit configured to analyze the signal indicative of the rotation characteristic of the rotating assembly. The bearing wear monitoring circuit is also configured to identify one or more signal characteristics indicative of bearing wear. The aspects recognize that a typical pump motor is configured to maintain a target rotational speed. The rotational speed of the rotating components of the pump motor configuration will be influenced by the torque of the motor rotor shaft. As a result, reaching the target rotational speed will be dependent on the shaft torque. Bearing wear causes variations in the rolling friction of the bearings, and is therefore one cause of shaft torque variations. The aspects recognize that the shaft torque variations can be indirectly monitored, measured and / or determined by suitable measurements or monitoring of the operating characteristics of the pump motor, and shaft torque variations due to bearing wear can be distinguished from shaft torque variations caused by one or more other factors.

Description

Technical Field

[0001] The technical field of the present invention relates to a bearing wear monitoring device, a bearing wear monitoring method, and a pump device including the bearing wear monitoring device. More specifically, the present disclosure relates to, but is not limited to, a bearing wear monitoring device for monitoring the operation of a vacuum pump, and a vacuum pump device including the bearing wear monitoring device.

Background Art

[0002] A pump system typically includes a pump having a stator and a rotating assembly portion, an inverter, and a pump controller. Examples of the target pump include a vacuum pump such as a turbo pump for pumping gas from a semiconductor tool or the like, or a multi-stage positive displacement pump. However, it should be understood that problems related to the operation of the pump are not limited to a specific type of pump mechanism. As described above, the pump typically includes an electric motor having a stator and a rotating assembly. The rotating assembly can include a motor rotor, a shaft, and a pump impeller. The rotor is usually attached so that the bearing ensures smooth rotation of the shaft associated with the rotor. Bearing wear is caused by, for example, damage to the associated raceway or damage to the bearing cage, which can cause an increase in the rolling friction force associated with the bearing, and as a result, may affect the operation of the pump and the pump system.

Summary of the Invention

Problems to be Solved by the Invention

[0003] In at least certain embodiments, the present invention seeks to eliminate or improve at least some of the limitations associated with the operation of a pump subject to bearing wear.

Means for Solving the Problems

[0004] A first embodiment provides a bearing wear monitoring device configured to monitor the bearings of a vacuum pump having an electric motor comprising a rotating assembly, the monitoring device comprising: an input receiving circuit configured to receive a signal indicating the rotational characteristics of the rotating assembly, wherein the signal indicating the rotational characteristics of the rotating assembly includes at least one of an index of rotational speed and an index of motor output; and a bearing wear monitoring circuit configured to analyze the signal indicating the rotational characteristics of the rotating assembly over time and to identify one or more signal characteristics indicating bearing wear.

[0005] The first aspect recognizes that, typically, the pump motor is configured to maintain a target rotational speed. The rotational speed of the rotating components forming the rotating assembly of the pump motor will be affected by the torque of the motor rotor shaft. As a result, reaching the target rotational speed will depend on the shaft torque. Bearing wear is one cause of shaft torque fluctuations because it causes fluctuations in the rolling friction of the bearings. Other factors can also cause shaft torque fluctuations, and in relation to the operation of the motor in a vacuum pump system, potential causes include changes in gas load, thermal effects, changes in back pressure, changes in the operating mode of the pump motor, and / or changes in the pump load.

[0006] The first aspect recognizes that shaft torque fluctuations can be indirectly monitored, measured, and / or determined by appropriate measurement or monitoring of the operating characteristics of the pump motor. The first aspect further recognizes that shaft torque fluctuations that may be due to bearing wear can be distinguished from shaft torque fluctuations caused by one or more other factors. These shaft torque fluctuations may cause abrupt deceleration of rotation and / or an increase in motor output required to maintain rotation.

[0007] It should be understood that the operating characteristics of a pump motor, which can help recognize variations in shaft torque, are typically related to indirect indicators of the state of rotational assembly motion. Variations in bearing rolling friction, which may be related to bearing wear, cause variations in the rotational motion of the shaft or motor rotor, which translates into pump operation. Rotational variations are related to changes in operation when the shaft or the motor driving the pump is adjusted, for example, to compensate for "sticking" caused by bearing wear.

[0008] The first aspect recognizes that by appropriately analyzing at least one of the rotational speed and motor output over time, it is possible to clarify characteristics that can be attributed to bearing wear.

[0009] In some embodiments, the signal characteristics are pre-set and indicate a known bearing wear state. Therefore, bearing wear can be indicated simply by detecting the signal characteristics.

[0010] In some embodiments, the device may include a user alarm configured to be triggered upon identification of one or more signal characteristics indicating bearing wear. The alarm condition may be communicated to the user or the pump control unit. The alarm may include visual or audible alarms. The alarm may trigger further actions, such as a safe pump shutdown.

[0011] In some embodiments, the signal indicating the rotational characteristics of the rotating assembly includes an index of the rotational speed.

[0012] Therefore, the rotational speed of the shaft or pump driven by the motor shaft can provide a mechanism for identifying the effect of bearing wear on the operation of the pump due to friction or seizing.

[0013] In some embodiments, signal characteristics indicating bearing wear include deceleration exceeding a predetermined threshold. Therefore, seizing associated with bearing or bearing cage wear can cause unexpected deceleration of the pump impeller, rotor, or shaft.

[0014] In some embodiments, the signal characteristics indicating bearing wear include identifying an increased deceleration compared to past deceleration events. In some embodiments, the signal characteristics indicating bearing wear include identifying an increased deceleration compared to known or planned deceleration events. In some embodiments, the signal characteristics indicating bearing wear include identifying an increased deceleration compared to a predetermined deceleration threshold.

[0015] In some embodiments, the signal indicating the rotational characteristics of the rotating assembly includes an indicator of motor output. An increase in output demand may indicate bearing wear, as the output increases to overcome seizing and friction.

[0016] In some embodiments, the characteristics of a signal indicating bearing wear include the motor output being at its maximum for a predetermined period of time.

[0017] In some embodiments, the input receiving circuit is configured to receive a signal indicating the operating characteristics of the vacuum pump, and the signal characteristics indicating bearing wear include the motor output being at maximum even though the signal indicating operating characteristics indicates that the vacuum pump is unlikely to require maximum motor output. Increases or maximization of motor output are expected at various points in normal pump operation. For example, in the case of a vacuum pump, maximum output may be required during the initial startup of the pump and when the gas load increases. Providing the bearing wear device with information indicating the operating status of the pump can prevent false activation of the bearing wear alarm.

[0018] In some embodiments, the signal indicating the rotational characteristics of the rotating assembly includes both an indicator of rotational speed and an indicator of motor output.

[0019] Either rotational speed or motor output measured over a certain period can indicate signs of bearing wear, but in some cases both are used to enable more accurate fault diagnosis.

[0020] In some embodiments, bearing wear fault diagnosis is related to the identification of one or more signal characteristics indicative of bearing wear. Accordingly, the nature of a bearing wear fault can be identified from the signal(s) being analyzed.

[0021] In some embodiments, the bearing wear monitoring device monitors the output during a period following a detected deceleration in response to determining that the deceleration exceeds a predetermined threshold, and the bearing wear fault diagnosis is configured to indicate bearing wear in response to an indication that the motor output monitored during this period exceeds a predetermined threshold.

[0022] In some embodiments, the bearing wear monitoring device can respond to the detection of a deceleration that exceeds a threshold for monitoring the consumed output. As described above, both the deceleration and the output are indicative of bearing wear, and generally deceleration is seen before an increase in output. Accordingly, by monitoring the output following a rapid deceleration, further evidence of bearing wear is presented, enabling a more reliable fault diagnosis.

[0023] A second aspect provides a vacuum pump device including the bearing wear monitoring device according to the first aspect.

[0024] A third aspect provides a method for monitoring bearing wear of a vacuum pump having an electric motor with a rotating assembly, the method comprising: receiving a signal indicative of a characteristic of rotation of the rotating assembly, the signal indicative of a characteristic of rotation of the rotating assembly including at least one of an indication of rotational speed and an indication of motor output; analyzing over time the signal indicative of a characteristic of rotation of the rotating assembly to identify one or more signal characteristics indicative of bearing wear; and.

[0025] In some embodiments, the signal characteristics are preset and indicative of a known bearing wear state.

[0026] In some embodiments, the method includes triggering a user alert upon identification of one or more signal characteristics indicative of bearing wear.

[0027] In some embodiments, the signal characteristic indicating bearing wear includes a deceleration rate exceeding a predetermined threshold value.

[0028] In some embodiments, the method includes identifying an increased deceleration rate compared to past deceleration events.

[0029] In some embodiments, the signal indicating the characteristics of the rotation of the rotating assembly includes an indicator of the motor output, and the method includes analyzing the motor output over time to identify one or more signal characteristics indicating bearing wear.

[0030] In some embodiments, the signal characteristic indicating bearing wear includes that the motor output is maximum for a predetermined time.

[0031] In some embodiments, the method includes receiving a signal indicating the operating characteristics of a vacuum pump, and the signal characteristic indicating bearing wear includes that the motor output is maximum even though the signal indicating the operating characteristics indicates that the vacuum pump is unlikely to require maximum motor output.

[0032] In some embodiments, the signal indicating the characteristics of the rotation of the rotating assembly includes an indicator of the temporal variation of the motor phase current, and the method includes converting the time-based signal into a frequency-based signal and analyzing the frequency-based signal to identify one or more signal characteristics indicating bearing wear.

[0033] In some embodiments, the signal indicating the characteristics of the rotation of the rotating assembly includes both an indicator of the rotational speed and an indicator of the motor output.

[0034] In some embodiments, this signal characteristic indicating bearing wear includes both a deceleration rate exceeding a predetermined threshold value and a motor output that is maximum over a predetermined time.

[0035] In some embodiments, the method monitors the output during the period following the detected deceleration in response to determining that the deceleration exceeds a predetermined threshold, and During this period, the system outputs an indicator showing bearing wear in response to an indicator that the monitored motor output exceeds a predetermined threshold. Includes.

[0036] In some embodiments, bearing wear failure diagnosis involves identifying one or more signal characteristics that indicate bearing wear.

[0037] A fourth aspect provides a computer program that includes computer-readable instructions configured, when executed by a processor, to cause a device to perform the method of the third aspect.

[0038] In some related embodiments, the signal indicating the rotational characteristics of a rotating assembly includes an index of the rotation period, and the bearing wear monitoring circuit is configured to analyze consecutive rotation periods to identify one or more signal characteristics indicating bearing wear. The rotation period may include the time to complete one rotation, and in some related embodiments, it may include the time to complete a partial rotation. Therefore, if the shaft or rotor becomes immobile as a result of bearing wear, small fluctuations in the rotation period are expected. By analyzing adjacent consecutive rotation periods to determine the fluctuation or variation in the time period, the type of friction typically caused by bearing wear can be identified.

[0039] In some related embodiments, the rotation period includes the time to complete a known angular rotation. An angular rotation may include, for example, one complete rotation, a partial rotation, or multiple consecutive rotations.

[0040] In some related embodiments, the signal characteristics indicating bearing wear include variations in the rotational period exceeding a predetermined threshold.

[0041] In some relevant embodiments, the signal characteristics indicating bearing wear include identifying an increase in the variation of the rotation period compared to past variations in the rotation period. Thus, the historical analysis of received signals in which bearing wear was determined not to be present can be stored for comparison.

[0042] In some related embodiments, the signal indicating the rotational characteristics of a rotating assembly includes an indicator of the time-dependent fluctuation of the motor's phase current, and the bearing wear monitoring circuit is configured to convert the time-based signal into a frequency-based signal and analyze the frequency-based signal to identify one or more signal characteristics indicating bearing wear. Since the pump operates to maintain a constant rotational speed, fluctuations in the current supplied to the motor can provide an indicator of the rotational fluctuations of the rotor / shaft / pump forming the rotating assembly. By converting the time-based signal into a frequency-based signal, signal characteristics that may indicate bearing wear can be easily identified.

[0043] It should be understood that one of the operating characteristics of a pump motor that can help recognize fluctuations in shaft torque is the current supplied to the pump motor when given the goal of maintaining rotational speed. Fluctuations in bearing rolling friction, which may be related to bearing wear, cause fluctuations in the current that are adjusted to compensate for "sticking".

[0044] Typically, the phase current indicator is reported to the user or system controller via a pump "output" measurement, which is refreshed and reported approximately every one or two seconds. This is effectively the "system output," and the time-averaged value obscures minute fluctuations in current that may be related to shaft torque variations due to bearing wear, making it difficult to decouple increased friction resulting from bearing wear from increased friction or torque due to other factors. As a result, pump "output" is not a good indicator of bearing wear. By avoiding the averaged current signal and instead examining minute fluctuations, characteristics related to bearing wear can be identified.

[0045] In some related embodiments, the signal characteristics indicating bearing wear include, in a frequency-based signal, at least one signal peak occurring at a preset frequency or within a preset frequency range. Bearing wear can typically occur in a given frequency range.

[0046] In some relevant embodiments, signal characteristics indicating bearing wear include signal peaks exceeding a preset threshold amplitude in the frequency-based signal. Therefore, unexpectedly large peaks in the frequency-based signal, even at frequencies where peaks are normally expected, may indicate bearing wear.

[0047] In some relevant embodiments, signal characteristics indicating bearing wear include identifying at least one new signal peak in the frequency-based signal compared to past patterns in the frequency-based signal. Thus, the appearance of new frequency characteristics compared to past frequency analysis of the signal may indicate bearing wear.

[0048] In some related embodiments, the signal indicating the rotational characteristics of a rotating assembly includes an index of the rotational period, and the method includes analyzing consecutive rotational periods to identify one or more signal characteristics indicating bearing wear.

[0049] In some relevant embodiments, the method includes identifying an increase in the rotation period variation compared to past variations in the rotation period.

[0050] In some related embodiments, the signal indicating the rotational characteristics of a rotating assembly includes an index of rotational speed, and the method includes analyzing the rotational speed over time to identify one or more signal characteristics indicating bearing wear.

[0051] Further specific and preferred embodiments are shown in the attached independent and dependent claims. Features of the dependent claims may be combined with features of the independent claims in combinations other than those expressly shown in the claims, where appropriate.

[0052] When a device feature is described as operable to provide a function, it should be understood that this includes device features that provide that function or are adapted or configured to provide that function. When a function is described as functional logic, it should be understood that this logic may be a configured circuit for performing that function.

[0053] Herein, embodiments of the present invention will be further described below with reference to the attached drawings. [Brief explanation of the drawing]

[0054] [Figure 1] Several key components of a vacuum pump system incorporating bearing wear monitoring devices in various embodiments and approaches described are schematically shown. [Figure 2] Figure 1 is a schematic diagram of the signals monitored by a bearing wear monitoring device. [Figure 3] Figure 1 is a schematic diagram of another signal monitored by a bearing wear monitoring device. [Figure 4] Figure 1 is a schematic diagram of another signal monitored by a bearing wear monitoring device. [Modes for carrying out the invention]

[0055] Before describing the embodiments in detail, an overview is first presented. A pump system typically comprises a pump including a stator and rotating assembly, an inverter, and a pump controller. Examples of pumps include vacuum pumps such as turbopumps for pumping gases from semiconductor tools, or multistage positive displacement pumps. However, it should be understood that problems related to pump operation are not limited to specific types of pump mechanisms. As mentioned above, a pump typically includes an electric motor with a stator and a rotating assembly. The rotor is usually mounted such that bearings ensure the smooth rotation of the shaft associated with the rotor. The shaft can drive the pump's impeller. The motor's rotor, shaft, and impeller together constitute a rotating assembly. Bearing wear, for example, due to damage to the associated raceway or bearing cage, can cause an increase in rolling friction associated with the bearing, which can consequently affect the operation of the pump and pump system. Because the shaft is driven by the motor, fluctuations in rolling friction can be measured as minute fluctuations in various operating characteristics of the motor. For example, changes in friction due to bearing wear can cause minute fluctuations in phase current and / or rotational speed. To detect or monitor such minute fluctuations, a measurement approach superior to the time-averaged values ​​provided by the user interface or system controller is generally required.

[0056] Next, pump systems in various configurations will be described. As described herein, the pump system 10 is configured to perform a self-diagnostic function in relation to bearing wear. Figure 1 schematically shows some of the main components of the vacuum pump system 10 incorporating bearing wear monitoring devices in various embodiments and approaches described.

[0057] The pump system 10 comprises a pump 20 driven by a motor 25, a power supply 30 and associated power supply electronic equipment 35, and a control unit 40. The pump 20 in the described configuration is a vacuum pump, such as a multistage positive displacement pump, for pumping gas from semiconductor tools or the like. However, it should be understood that the approach described in relation to this configuration is not limited to a specific type of pump mechanism.

[0058] The electric motor 30 comprises a stator and a rotor. The rotor is coupled to a shaft that drives the pump 20. The rotor and shaft are associated with bearings, enabling smooth rotation of the shaft and transmission of rotation to the pump. The control unit 40 is configured to communicate with the pump power supply electronic equipment 35 to control the operation of the motor 25 that drives the pump 20. The control unit also provides a human-machine interface (HMI) to facilitate control of the pump 20. The control unit 40 comprises a control circuit and control software configured to process signals received from various components of the pump system 10 and from one or more sensors associated with the components of the pump system. The control unit is configured to use the control circuit to process these input signals and generate one or more outputs that can be transmitted to one or more components of the pump system and control the operation of the pump 20.

[0059] The pump system 10 shown in Figure 1 includes a bearing wear monitoring device 50. Although shown as part of the control unit 40, it should be understood that in some embodiments, a separate bearing wear monitoring device can be provided, which can be configured to communicate with the control unit 40. The bearing wear monitoring device 50 includes bearing wear logic or circuitry and processing capabilities, and is configured to process signals received from various components of the pump system 10 and from one or more sensors associated with the components of the pump system. The bearing wear monitoring device is configured to process these input signals using a control circuit and produce one or more outputs that are transmitted to the control unit 40 and / or one or more components of the pump system, which can consequently directly or indirectly affect the operation of the pump 20. The bearing wear monitoring device can be associated with the operation of a bearing wear alarm 55. The bearing wear alarm 55 can be configured to provide a visual or audible alarm to the system user when the bearing wear monitoring device 50 detects potential bearing wear.

[0060] In the configuration shown in Figure 1, the bearing wear monitoring device communicates with the rotor position measuring device 60. This rotor position measuring device 60 can be configured to measure or estimate the rotational motion of the shaft driven by the motor 25. The rotor position measuring device 60 can measure the rotor position using, for example, one or more Hall switches, encoders, or other position measuring or estimation devices. An example of the signal 65 generated by the rotor position measuring or estimation device 60 is shown, which takes the form of one or more pulses generated for each rotation of the rotor or shaft. The bearing wear monitoring device shown in Figure 1 also communicates with the power supply electronic equipment 35 and the control unit 40.

[0061] Various approaches that can be used to configure the bearing wear monitoring device 50 to provide an evaluation of bearing wear are described in detail. Some approaches described may be based on taking multiple measurements for each rotation of the shaft, while others may be based on measurements taken over a longer period, for example, a period encompassing multiple shaft rotations.

[0062] Four general approaches will be described in detail. It should be understood that the details of these general approaches can be combined as appropriate to provide a hybrid approach that similarly offers a mechanism for evaluating bearing wear.

[0063] Two of the general approaches rely on very fast measurements (microseconds to milliseconds). Two of the general approaches rely on longer-duration measurements (~seconds).

[0064] According to one schematic related approach, the bearing wear logic can be configured to record or monitor the motor phase current supplied to the motor 25 by the power supply electronics 35 in an attempt to provide a constant rotational speed. The bearing wear monitoring device is configured to convert the recorded or monitored motor phase current into the frequency domain. The motor phase current can be measured or monitored for each shaft rotation, or for a portion of rotations (e.g., once per rotation, corresponding to a measurement of 1 ms at a shaft speed of 1 kHz), or for a small number of shaft rotations (e.g., 5 to 10 rotations, corresponding to 5 to 10 ms at a shaft speed of 1 kHz). Analysis in the frequency domain allows the bearing wear logic to identify components at characteristic bearing failure frequencies. These frequencies can be preset based on an analysis of the pump having bearing wear failure modes, or they can include "new" frequency characteristics identified by comparing them with past frequency analyses of pump operation.

[0065] According to one schematic related approach, the bearing wear logic or circuitry provided as part of the bearing wear monitoring device 50 can be configured to measure or monitor the time it takes for the shaft to complete one rotation or other fixed angular motion. In other words, the bearing wear monitoring device can analyze the signal 65 received from the rotor position measuring device 60. The measurement can be repeated over a series of consecutive angular motions. The bearing wear logic can be configured to compare adjacent measurement or monitoring times. By comparing times, the logic can identify variations in monitoring times that indicate bearing "snagging" due to wear of bearing components and the resulting friction.

[0066] The advantage of the two schematic related approaches described above lies in the fact that measurement and monitoring are performed at a sufficiently fast speed, largely independent of pump factors, in contrast to bearing factors. For example, as mentioned above, for a pump operating at 1 kHz, it would take 10 msec to measure 10 consecutive rotations of the shaft. By comparing and evaluating the duration of each of these 10 consecutive rotations, bearing wear can be determined. Pump factors such as changes in gas load, thermal effects, and changes in back pressure are unlikely to cause variations in shaft rotation time or speed over 10 ms that could be mistaken for variations caused by bearing wear. In other words, the two schematic related approaches described provide a bearing wear logic configured to collect and process rotor operating parameters very quickly in order to eliminate variations caused by macroscopic effects on the vacuum system 10.

[0067] According to one schematic approach in one embodiment, the bearing wear logic may be configured to measure or monitor the pump rotational speed or shaft rotational speed and identify if the rate of change of the rotational speed exceeds the rate of change associated with the expected pump condition. In other words, the bearing wear monitoring device may be configured to identify a deceleration or acceleration determined from a signal 65 from a rotor position measuring device 60, process the signal, and identify whether the determined rate of change exceeds the rate of change associated with an allowable and / or expected pump condition, such as an emergency stop.

[0068] According to one schematic approach in an embodiment, the bearing wear logic can be configured to monitor and / or measure the pump output based on an analysis of the power supply signal from the power supply electronic equipment 35 and to identify a state in which a preset threshold maximum output is required by the pump control unit 40 when it is unexpected under known pump operating conditions.

[0069] The two schematic approaches described above may utilize high-speed acquisition and processing as explained in relation to the previously mentioned related approaches, or they may be performed at lower measurement and processing speeds. To distinguish variations in bearing wear at rotation, the schematic approaches performed at slower speeds may require at least some knowledge of the expected range of pump operation in order to identify the time when the rotational speed decelerates or accelerates and / or pump output falls outside the expected operating limits. In some embodiments, the two schematic approaches performed at low speeds may be combined to monitor both deceleration and consumed output for use in determining bearing wear. In this regard, abrupt deceleration may indicate bearing wear, but it may also indicate a change in pumping conditions. The output consumed immediately or after this may provide further information about the cause of the deceleration and can be used to substantially approve or reject a fault diagnosis.

[0070] After outlining the four general approaches, we will describe each approach in detail.

[0071] (phase current) As described above, some approaches provide bearing wear logic configured to monitor and / or measure the phase current over very short time intervals, such as once, twice, or more times per shaft revolution, and then perform a conversion of the monitored phase current to the frequency domain. By converting the current to the frequency domain, components at specific frequencies can be decomposed, and frequencies typically associated with bearing wear can be identified. For example, the synchronous frequency can be filtered from the frequency-converted signal, and other frequencies of interest, such as ball passage frequency, bearing cage frequency, etc., can be identified, extracted, and monitored. Such values ​​can be tracked, for example, throughout the life of a pump, and compared to a predetermined threshold or to previous values ​​in order to identify bearing wear or bearing-related failures. For example, the bearing cage frequency (quasi-synchronous frequency) can be a good indicator of a particular failure mode and can be a useful parameter to measure and track over time. Of course, it should also be understood that the phase current is usually a ripple current locked to the switching frequency, and each measurement itself may contain an indicator of an averaged value.

[0072] (Shaft rotation time) As described above, several approaches provide bearing wear logic configured to measure and monitor the time it takes to complete one rotation (or half a rotation, or other fixed angular motion depending on the number of poles of the motor and the precise measurement implementation configuration) as a means of monitoring bearing wear factors. By monitoring the rotation time and comparing it to a baseline and / or previous value, it is possible to identify whether there are localized high-friction areas in the bearing that suggest signs of wear.

[0073] Figure 2 is a schematic diagram of the signals monitored by the bearing wear monitoring device shown in Figure 1. More specifically, Figure 2 shows the signals 65 that can be generated by the rotor position measuring device 60. The illustrated signals are plots of estimated values ​​against time, which change sinusoidally with the rotor angle, allowing us to see the variations between adjacent rotations T1, T2, and T3. These variations are analyzed by the bearing wear monitoring device 50, which can identify inconsistent variations between each rotation caused by frictional changes indicating bearing wear.

[0074] (Rotor deceleration) As described above, several approaches according to the embodiments provide bearing wear logic configured to measure and monitor the deceleration of a rotor or pump. If the logic determines that the measured rotor deceleration is outside the expected range, it can be configured to alert the user, trigger an alarm, or adjust the operating parameters of the pump rotor. For example, different decelerations can be set for each type of pump in relation to expected operating events such as controlled braking, degassing, and gas loading. A certain understanding and knowledge of such events can help provide an index of the normal operating deceleration and assist in selecting an appropriate maximum expected deceleration. Once a deceleration threshold is selected, the bearing wear logic can be configured to continuously monitor the rotational speed of the pump and, if the deceleration exceeds the maximum expected threshold, trigger the identification of a condition likely to fail. In some embodiments, instead of immediately triggering the identification of a condition likely to fail, the detection of deceleration rather triggers monitoring of the output consumed, and only if this exceeds a threshold is a potential failure identified. In either case, once a condition likely to fail is identified, an alarm or other similar signal may be triggered to alert the pump user of the fault condition. In some implementation configurations, the bearing wear logic can be combined with the pump control logic to configure the pump to enter fail-safe mode and stop pump operation. Stopping the pump in a controlled manner without intervention is advantageous in the case of unattended pumps.

[0075] Figure 3 is a schematic diagram of another signal monitored by the bearing wear monitoring device shown in Figure 1. More specifically, Figure 3 shows signals that may arise from monitoring the rotational speed of the pump or motor shaft over time. Under normal pump operation, a substantially constant target rotational speed is maintained. The dashed line (b) indicates deceleration of the motor shaft or pump due to expected operating conditions, and the solid line (a) indicates deceleration expected from bearing failure. The rate of change in rotational speed is analyzed by the bearing wear monitoring device 50, which can identify deceleration exceeding a selected threshold that indicates bearing wear or bearing failure.

[0076] (Motor output request) As described above, several approaches provide bearing wear logic configured to measure and monitor motor output. The bearing wear logic can be configured to identify a potentially faulty condition and trigger an alarm if the output exceeds a maximum expected threshold or reaches maximum output. The bearing wear logic can be configured to monitor additional pump control parameters to help identify situations where a maximum output request indicates a bearing wear problem. In detail, for example, during pump ramping or pump startup when maximum output is supplied to accelerate the pump to full speed, the logic can be configured to ignore alarm conditions or prevent the triggering of alarm conditions. According to some embodiments, bearing wear logic implementing a motor output request monitoring regime can link such regimes to the monitoring or evaluation of one or more additional pump parameters, such as rotational speed, deceleration, or time since the START command was received. The motor output request bearing wear approach can be activated when a combination of thresholds or trigger conditions related to one or more signals is met. Approaches using motor output bearing wear monitoring can be used in particular in relation to pump applications where the gas load is known and the load on the pump due to the gas load is less than the maximum value set in the drive unit.

[0077] Figure 4 is a schematic diagram of another signal monitored by the bearing wear monitoring device shown in Figure 1. More specifically, Figure 4 plots the change in the monitored motor output over time. When the pump is not under a large gas load, the motor output should normally be substantially constant. Similarly, when the pump is under an increasing but constant gas load, the motor output increases but is also substantially constant. During rapid changes in gas load or initial startup, the maximum motor output may occur and be maintained for a certain period, as shown by peak C in Figure 4. Otherwise, determining that the motor is operating at maximum output in a manner not caused by an expected change in pump condition may indicate a pump failure. Such a failure condition is shown as peak A in Figure 4. The peak or maximum value of the motor output is analyzed by the bearing wear monitoring device 50, which can identify, for example, unexpected periods of maximum output indicating bearing wear.

[0078] It should be understood that the bearing wear monitoring approaches described separately above can be used in combination. In detail, an alarm or system shutdown may be triggered when bearing wear is determined according to one of the described approaches, but advantageously, it may also be triggered when two or more threshold conditions (each depending on different monitoring rotor operating parameters) indicating potential bearing wear are met.

[0079] While exemplary embodiments of the present invention have been disclosed in detail herein with reference to the accompanying drawings, it will be understood that the present invention is not limited to these exact embodiments and that various changes and modifications can be achieved by those skilled in the art without departing from the scope of the invention as defined by the claims and equivalents.

[0080] Various related embodiments and / or examples are described in the following numbered sections.

[0081] (Clause 1) A bearing wear monitoring device configured to monitor the bearings of a vacuum pump having an electric motor equipped with a rotating assembly, wherein the bearing wear monitoring device is An input receiving circuit configured to receive a signal indicating the rotational characteristics of a rotating assembly, A bearing wear monitoring circuit is configured to analyze signals indicating the rotational characteristics of a rotating assembly and to identify one or more signal characteristics indicating bearing wear. It is equipped with.

[0082] (Article 2) The bearing wear monitoring device described in Clause 1 has pre-set signal characteristics that indicate known bearing wear conditions.

[0083] (Article 3) A bearing wear monitoring device according to clause 1 or 2, including a user alarm configured to be triggered when one or more signal characteristics indicating bearing wear are identified.

[0084] (Article 4) A bearing wear monitoring device according to any one of clauses 1 to 3, wherein the signal indicating the rotational characteristics of the rotating assembly includes an index of the rotation period, and the bearing wear monitoring circuit is configured to analyze consecutive rotation periods to identify one or more signal characteristics indicating bearing wear.

[0085] (Article 5) A bearing wear monitoring device as described in Clause 4, wherein the rotation period includes the time required to complete a known angular rotation.

[0086] (Article 6) The bearing wear monitoring device according to Clause 4 or 5, wherein the signal characteristic indicating bearing wear is a variation in the rotation period that exceeds a predetermined threshold.

[0087] (Article 7) A bearing wear monitoring device according to any one of clauses 4 to 6, wherein the signal characteristics indicating bearing wear include an index of increased rotational period variation compared to past rotational period variations.

[0088] (Clause 8) A bearing wear monitoring device according to any one of clauses 1 to 7, wherein the signal indicating the rotational characteristics of the rotating assembly includes an index of rotational speed, and the bearing wear monitoring circuit is configured to analyze the rotational speed over time and identify one or more signal characteristics indicating bearing wear.

[0089] (Article 9) The bearing wear monitoring device according to Clause 8, wherein the signal characteristics indicating bearing wear include deceleration exceeding a predetermined threshold.

[0090] (Clause 10) A bearing wear monitoring device according to Clause 8 or 9, wherein the signal characteristics indicating bearing wear include the identification of an increased degree of deceleration compared to past deceleration events.

[0091] (Article 11) A bearing wear monitoring device according to any one of clauses 1 to 9, wherein the signal indicating the rotational characteristics of the rotating assembly includes an index of motor output, and the bearing wear monitoring circuit is configured to analyze the motor output over time to identify one or more signal characteristics indicating bearing wear.

[0092] (Article 12) The bearing wear monitoring device according to Clause 11, wherein the signal characteristics indicating bearing wear include the motor output being at its maximum for a predetermined period of time.

[0093] (Article 13) The bearing wear monitoring device according to Clause 11 or 12, wherein the input receiving circuit is configured to receive a signal indicating the operating characteristics of the vacuum pump, and the signal characteristics indicating bearing wear include the motor output being at maximum even though the signal indicating the operating characteristics indicates that the vacuum pump is unlikely to require maximum motor output.

[0094] (Article 14) A bearing wear monitoring device according to any one of the clauses 1 to 13, wherein the signal indicating the rotational characteristics of the rotating assembly includes an indicator of the temporal fluctuation of the motor's phase current, and the bearing wear monitoring circuit is configured to convert the time-based signal into a frequency-based signal and analyze the frequency-based signal to identify one or more signal characteristics indicating bearing wear.

[0095] (Article 15) The bearing wear monitoring device according to Clause 14, wherein the signal characteristics indicating bearing wear include, in a frequency-based signal, at least one signal peak occurring at a preset frequency or a preset frequency range.

[0096] (Article 16) The bearing wear monitoring device according to Clause 14 or 15, wherein the signal characteristics indicating bearing wear include signal peaks exceeding a preset threshold amplitude in a frequency-based signal.

[0097] (Article 17) A bearing wear monitoring device according to any one of clauses 14 to 16, wherein the signal characteristics indicating bearing wear include the identification of at least one new signal peak in the frequency-based signal compared with past patterns in the frequency-based signal.

[0098] (Article 18) A bearing wear monitoring device according to any one of the clauses 1 to 17, wherein the fault diagnosis of bearing wear is associated with the identification of one or more signal characteristics indicating bearing wear.

[0099] (Article 19) A vacuum pump apparatus equipped with a bearing wear monitoring device as described in any of clauses 1 to 18.

[0100] (Article 20) A method for monitoring bearing wear in a vacuum pump having an electric motor with a rotating assembly, A step of receiving a signal that indicates the rotational characteristics of the rotating assembly, The steps include analyzing signals that indicate the rotational characteristics of a rotating assembly and identifying one or more signal characteristics that indicate bearing wear, A method that includes this.

[0101] (Article 21) A computer program containing computer-readable instructions, which, when executed by a processor, is configured to cause a device to perform the actions described in Clause 20. [Explanation of Symbols]

[0102] 10 Pump System 20 pumps 25 Motor 30 power supply 35 Power supply electronics 40 Control Units 50 Bearing wear monitoring device 55 Bearing wear alarm 60 Rotor position measuring device

Claims

1. A bearing wear monitoring device configured to monitor bearing wear of a vacuum pump having an electric motor with a rotating assembly, An input receiving circuit configured to receive a signal indicating the rotational characteristics of the rotating assembly, wherein the signal indicating the rotational characteristics of the rotating assembly includes both an indicator of rotational speed and an indicator of motor output. A bearing wear monitoring circuit is configured to analyze signals indicating the rotational characteristics of the rotating assembly over time and to determine whether the deceleration of the rotational speed exceeds a predetermined threshold. Equipped with, The bearing wear monitoring device is configured to monitor the motor output during the period following a determination that the deceleration of the rotational speed exceeds a predetermined threshold, in response to the determination that the deceleration exceeds a predetermined threshold. The bearing wear monitoring device determines that the motor output monitored during the period exceeds a predetermined threshold, and diagnoses bearing wear.

2. The bearing wear monitoring device according to claim 1, further comprising a user alarm configured to be triggered when the bearing wear monitoring device determines that the deceleration of the rotational speed exceeds a predetermined threshold, or when it determines that the motor output monitored during the period exceeds a predetermined threshold.

3. A vacuum pump device comprising the bearing wear monitoring device according to claim 1 or 2.

4. A method for monitoring bearing wear in a vacuum pump having an electric motor with a rotating assembly, A step of receiving a signal indicating the rotational characteristics of the rotating assembly, wherein the signal indicating the rotational characteristics of the rotating assembly includes both an indicator of rotational speed and an indicator of motor output. The steps include analyzing a signal indicating the rotational characteristics of the rotating assembly over time and determining whether the deceleration of the rotational speed exceeds a predetermined threshold, In response to determining that the deceleration exceeds the predetermined threshold, the motor output is monitored during the period following the determination, and if the motor output monitored during the period exceeds the predetermined threshold, bearing wear is diagnosed. A method that includes this.

5. A computer program comprising computer-readable instructions configured, when executed by a processor, to cause a device to perform the method described in claim 4.

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