Method and device for operating and recalibrating a lubricant sensor in a technical system with a lubricant circuit

Abstract

The invention relates to a method for the automatable recalibration of at least one lubricant sensor (51) of a sensor module (5) in a technical system (1) with a mechanical unit (2), wherein the sensor module (5) is arranged in a lubricant circuit with lubricant used by the mechanical unit (2), said method having the following steps: - evacuating (S2) at least part of the lubricant circuit (3) such that the sensor module (5) with the at least one lubricant sensor (51) is free of the lubricant used by the mechanical unit (2); - circulating reference lubricant in the lubricant circuit (3) through the sensor module (5); - carrying out at least one reference measurement with the aid of the at least one lubricant sensor (51) when the reference lubricant is flowing through the sensor module (5); - evacuating (S8) the lubricant circuit (3) after the at least one reference measurement; - filling (S10) the lubricant circuit (3) with lubricant used by the mechanical unit (2); - operating (S10) the technical system (1) with the used lubricant and depending on the result of the at least one reference measurement.

Description

[0001] Method and device for operating and recalibrating a lubricant sensor in a technical system with a lubricant circuit

[0002] Technical area

[0003] The invention relates to methods for monitoring a lubricant in technical systems with a mechanical unit, such as a transmission, a rolling bearing, and the like. The invention further relates to measures for ensuring proper sensory detection of a lubricant condition using a lubricant sensor.

[0004] Technical background

[0005] In technical systems with mechanical units, such as gears, rolling bearings, and the like, lubricant is circulated in a lubricant circuit to reduce wear on moving parts and to clean and cool the mechanical unit. Due to the operation of the technical system, the lubricant becomes contaminated over time with wear particles and / or thermal degradation and / or water penetration or condensation, resulting in a degradation of its lubricating properties.

[0006] To continuously monitor lubricant quality, one or more lubricant sensors are typically installed to record the properties or condition of the lubricant. For example, sensors can measure optical transparency, viscosity, electrical properties such as ohmic resistance, capacitance, and the like. By monitoring these properties, the aging of the lubricant can be tracked and when it needs to be replaced can be determined. The fundamental problem with sensor-based measurements is that, due to sensor drift over time, the measurement of lubricant properties becomes less accurate, so a high tolerance range must be assumed for evaluating the measured values ​​and determining lubricant degradation.

[0007] It is therefore an object of the present invention to provide an improved method for ensuring correct measured values ​​of a lubricant sensor, with which the aging or degradation of the lubricant can be better monitored.

[0008] Disclosure of the invention

[0009] This object is achieved by the method for recalibrating a lubricant sensor in a technical system with a lubricant circuit according to claim 1 and a device according to the independent claim.

[0010] Further embodiments are specified in the dependent claims.

[0011] According to a first aspect, a method is provided for recalibrating at least one lubricant sensor of a sensor module in a technical system with a mechanical unit, wherein the sensor module is arranged in a lubricant circuit with lubricant used by the mechanical unit, comprising the following steps:

[0012] Emptying the lubricant circuit in which the sensor module with the at least one lubricant sensor is arranged;

[0013] Circulating reference lubricant in the lubricant circuit;

[0014] Carrying out a reference measurement using the at least one lubricant sensor when the reference lubricant flows through the sensor module;

[0015] Emptying the lubricant circuit after the reference measurement; filling the lubricant circuit with the lubricant used by the mechanical unit;

[0016] Operating the technical system with the lubricant used depends on the result of the reference measurement.

[0017] In technical systems with a lubricant circuit, one or more lubricant sensors are typically provided in a sensor module to monitor the properties or condition of the lubricant based on measured variables. These properties can be evaluated using suitable models to track lubricant aging and determine the lubricant's aging state. These models can provide a simple threshold comparison or more complex functions to calculate the aging state based on the sensor variables. However, the aging state depends significantly on the measurement accuracy of the lubricant sensors.

[0018] It can be provided that a sensor offset of the at least one lubricant sensor is determined depending on the result of the reference measurement, wherein the sensor offset is used to apply measured variables of the at least one lubricant sensor.

[0019] As is common with many sensors, lubricant sensors are also subject to sensor drift, which results in a varying offset deviation being added to the measured variable over their lifetime. The above procedure involves using recalibration to determine a sensor offset that serves to compensate for the sensor drift. This allows the sensor behavior to be reset to its initial state, so that the models used to determine the aging state or degradation of the lubricant from the measured variables can still be used.

[0020] Furthermore, it can be provided that a first control valve and a second control valve are arranged at a first end and a second end of the sensor module respectively for emptying the lubricant circuit, wherein the separation of the lubricant circuit occurs by appropriate adjustment of the control valves. For this purpose, a sensor module is provided which comprises at least one lubricant sensor and whose lubricant circuit can be separated from a mechanical unit using a suitable valve arrangement and can be flushed with a reference lubricant, such as the same, but unused lubricant as is provided for the operation of the mechanical system. This enables monitoring of the measured values ​​of the at least one lubricant sensor, wherein the change in the measured value of the current reference measurement compared to the measured value in a reference measurement can be provided as a sensor offset in order to compensate for sensor drift.The reference measurement can correspond to a measurement of measured values ​​when commissioning the sensor module or a new sensor module, at the start of monitoring the sensor module, during a lubricant change or the like.

[0021] To perform the reference measurement, the valve arrangement is positioned so that the lubricant circuit is formed with the sensor module and a lubricant pump. The lubricant circuit is first pumped empty using the lubricant pump so that the lines and sensor module of the lubricant circuit are free of used lubricant for the reference measurement. This can preferably be achieved by operating the lubricant pump in reverse to pump the lubricant in the lubricant circuit back into the mechanical unit.

[0022] The emptying of the sensor module and the lines in the lubricant circuit can be carried out by operating the lubricant pump for a predetermined period of time, or it can be detected based on the measured values ​​of the at least one lubricant sensor of the sensor module when it is free of used lubricant and then the lubricant pump can be switched off.

[0023] Furthermore, the reference lubricant can be stored in a reference lubricant container, from which the reference lubricant is withdrawn for performing the reference measurement and returned after the reference measurement. In a subsequent process step, the reference lubricant is pumped from a reference lubricant container into the lubricant circuit and the sensor module. A continuous, predetermined, and constant lubricant flow is set. This allows a continuous flow of the reference lubricant through the sensor module when the pump is operating at a fixed speed or controlled based on a measured lubricant flow.

[0024] Furthermore, by operating a heater, the lubricant can be heated to a desired measuring temperature for the reference measurement, since some sensors are temperature dependent.

[0025] A reference measurement is performed with at least one lubricant sensor. For this purpose, the measured values ​​of the measured variables are stored in a control unit.

[0026] Alternatively, several reference measurements can be performed at different specified temperatures for recalibration. Provided initial reference measurements were performed at the different specified temperatures, a sensor offset can be determined for each of the different specified temperatures. These can be stored in a lookup table, allowing a sensor offset to be applied depending on the operating temperature of the technical system. This offset can be derived directly from the lookup table or determined by interpolation.

[0027] After the corresponding measurements have been taken with at least one lubricant sensor at a specified lubricant flow of the reference lubricant and, if applicable, at one or more specified temperatures of the reference lubricant, the reference lubricant is pumped from the lubricant circuit back into the reference lubricant reservoir. This is achieved by operating the lubricant pump, preferably in reverse, until the sensor module and the corresponding lines of the sub-circuit are completely emptied. The control valves of the valve arrangement are then reset to enable proper operation with the used lubricant in the technical system. For this purpose, the lubricant pump is operated in the forward direction to pump the used lubricant through the lubricant circuit into the mechanical unit of the technical system.

[0028] The above method enables a particularly efficient recalibration of lubricant sensors in a sensor module for measuring the properties of a circulating lubricant during operation, without having to remove the sensor module or individual lubricant sensors, and without having to replace the lubricant in use. Furthermore, the process can be automated.

[0029] It can further be provided that several reference measurements for calibrating a respective lubricant sensor are carried out with different reference lubricants in respective reference lubricant containers, from which the respective reference lubricant is taken to carry out the corresponding reference measurement and is returned again after the corresponding reference measurement.

[0030] According to a further aspect, a device, in particular a control unit, is provided for carrying out the above method.

[0031] According to a further aspect, a technical system is provided, comprising: a mechanical unit; a sensor module with at least one lubricant sensor; a lubricant pump; a lubricant circuit designed to circulate the lubricant used in the mechanical unit through the sensor module with the aid of the lubricant pump; a valve arrangement for isolating the lubricant circuit in which the sensor module is located; at least one control unit designed to o control the valve arrangement and the lubricant pump such that the part separated from the lubricant circuit is emptied, o allow reference lubricant to circulate in the lubricant circuit; o carry out a reference measurement with the aid of the at least one lubricant sensor when the reference lubricant flows through the sensor module; o empty the lubricant circuit after the reference measurement;o to fill the lubricant circuit with used lubricant; o to operate the technical system with the used lubricant and depending on the result of at least one reference measurement;

[0032] The control unit can be located locally near the mechanical unit and / or remotely via a cloud-based system. In particular, the control unit can be designed in two parts, with a local part controlling the valve assembly and the lubricant pump, and the evaluation of the reference measurement being performed via a cloud-based system.

[0033] Brief description of the drawings

[0034] Embodiments are explained in more detail below with reference to the attached drawings. They show:

[0035] Figure 1 shows a schematic representation of a technical system with a lubricant circuit and an arrangement for carrying out a reference measurement of at least one lubricant sensor; and

[0036] Figure 2 shows a flowchart illustrating the method for recalibrating at least one lubricant sensor. Description of embodiments

[0037] Figure 1 schematically shows a technical system 1 with a mechanical unit 2, such as a transmission, and with a lubricant circuit 3 in which a controllable lubricant pump 4 and a sensor module 5 are arranged. The lubricant circuit 3 fluidically connects the aforementioned elements for transporting a lubricant used in the mechanical unit 2 through the sensor module 5 with the aid of the lubricant pump 4.

[0038] The sensor module 5 in the lubricant circuit 3 has at least one lubricant sensor 51. The at least one lubricant sensor 51 can be a viscosity sensor, a contamination sensor, a

[0039] Compensation temperature sensor, a conductivity sensor, a permittivity sensor, a transmission sensor, an IR sensor (mid-IR and NIR), a relative humidity sensor, an optical particle sensor, an inductive particle sensor, a fluorescence sensor, and the like. The lubricant pump 4 is directly connected to the sensor module 5.

[0040] Furthermore, a flow sensor 6 and a temperature sensor 7 can be provided in the lubricant circuit 3. A first control valve 8 is provided in the lubricant circuit to control the lubricant flow. The first control valve 8 is arranged between the lubricant pump 4, a reference lubricant reservoir 9, and the mechanical unit 2.

[0041] A second control valve 10 is provided between the sensor module 5, the mechanical unit 2, and an inlet of the reference lubricant reservoir 9. The reference lubricant reservoir 9 can contain reference lubricant, such as unused lubricant or unused lubricant with additives. The first and second control valves 8, 10, as well as the lubricant sensors 51, are connected to a control unit 11.

[0042] In an alternative embodiment, several reference lubricant containers can be provided, each of which can be used separately via a corresponding valve system. These containers can be filled with unused lubricant and unused lubricant containing additives. This allows for several reference measurements to be taken consecutively using different reference lubricants. The reference lubricants can be configured to measure a respective lubricant sensor to be calibrated in the sensor module.

[0043] The control unit 11 is configured to perform a method for recalibrating the sensor to determine sensor offsets for the at least one lubricant sensor 51, which can be used to compensate for the aging-related and / or contamination-related sensor drift. The control unit 11 can be provided locally and / or cloud-based.

[0044] A heater 12 can also be provided to set various predetermined temperatures of the lubricant. Thus, a reference measurement can be performed for each of the lubricant sensors 51 in the sensor module 5 at different lubricant temperatures to obtain reference values. The respective sensor offsets are thus determined with reference to the reference values ​​of an initial reference measurement for each lubricant sensor 51 and for each of the predetermined temperatures. Multiple sensor offsets for a lubricant sensor 51 at different temperatures can be stored in a map or a lookup table, so that the appropriate sensor offset can be applied depending on the operating temperature.

[0045] The process for performing the recalibration is described in more detail in the flow chart in Figure 2. During normal operation, in a first valve position, the first control valve 8 connects the lubricant pump 4 to the mechanical unit 2 and blocks the connection to the reference lubricant reservoir 9. The second control valve 10, in a first valve position, connects the sensor module 5 to the mechanical unit 2, so that the lubricant circuit is closed and directly connected to the mechanical unit 2, with access to the reference lubricant reservoir 9 blocked. The lubricant pump 4 conveys the lubricant in a forward direction from the mechanical unit 2 via the lubricant pump 4 toward the sensor module 5, so that regular measurements of sensor variables can be performed there.

[0046] To perform a recalibration, in an optional step S1, the first control valve 8 is initially left in the first valve position, in which it connects the lubricant pump 4 to the mechanical unit 2. The second control valve 10 can optionally be switched from a connection of the sensor module 5 to the mechanical unit 2 to a second valve position, i.e., a connection of the sensor module 5 to the reference lubricant reservoir 9 and blocking the connection to the mechanical unit 2 if it cannot be ensured that air from the mechanical unit 2 is sucked into the lubricant circuit. The connection between the second control valve 10 and the reference lubricant reservoir 9 is such that only an inlet is formed, through which air can be sucked into the lubricant circuit.

[0047] In step S2, the lubricant pump 4 is operated in reverse to pump the lubricant out of the sensor module 5 and the line areas between the second control valve 10 and the sensor module 5 until there is no more used lubricant in the lines between the first and second control valves 8, 10 and the sensor module 5.

[0048] After emptying the sensor module, the first control valve 8 is moved to a second valve position in step S3. In the second valve position, the first control valve 8 connects the lubricant pump 4 to the reference lubricant reservoir 9 and blocks the connection to the mechanical unit 2, i.e., the lubricant pump 4 is directly connected to the reference lubricant reservoir 9 and separated from the mechanical unit 2. Furthermore, the second control valve 10 is switched to the second valve position, so that the sensor module 5 is directly connected to the reference lubricant reservoir 9, thus closing a separate circuit for the reference lubricant.

[0049] In step S4, the lubricant pump 4 is operated in the forward direction, so that the reference lubricant flows through the separate circuit with the sensor module 5. The lubricant pump 4 is operated in such a way that a specific, predefined reference lubricant flow is achieved in the partial circuit. For this purpose, the lubricant pump 4 can be operated at a fixed speed or in controlled mode, with the controlled variable being provided as a measured variable of the flow sensor 6.

[0050] Furthermore, in step S5, the heater 12 can be started and the temperature of the reference lubricant can be checked using the temperature sensor. In particular, the temperature of the reference lubricant is set to one or more predetermined temperatures, such as 40°C and 60°C.

[0051] Once the preset temperature is reached, a reference measurement is performed with the sensor module 5 in step S6. The reference measurement results in sensor values ​​from the at least one lubricant sensor 51 that correspond to the reference lubricant, such as the lubricant in new condition.

[0052] By comparing with an initial reference measured variable, which can correspond to the respective measured variable for new, unused lubricant upon commissioning of the technical system 1, a sensor drift can be determined as a difference in step S7, which can be taken into account as a sensor offset in subsequent measurements with the sensor module 5. The reference measurements can be performed at multiple temperatures, so that the respective sensor offset for the respective temperature results from an initial reference measured variable for the corresponding temperature and the current reference measured variable.

[0053] After performing the reference measurement, in step S8, the lubricant pump 4 is operated in reverse to pump the reference lubricant in the circuit back into the reference lubricant reservoir 9. This continues until the entire subcircuit is completely emptied of reference lubricant.

[0054] After emptying the sensor module 5, in step S9, the first control valve 8 is moved to a first valve position, in which the first control valve 8 separates the lubricant pump 4 from the reference lubricant reservoir 9 and re-establishes the connection to the mechanical unit 2. Furthermore, the second control valve 10 is switched to the first valve position, so that the sensor module 5 is separated from the reference lubricant reservoir 9, thus restoring the lubricant circuit.

[0055] Subsequently, in step S10, the first control valve 8 and the second control valve 10 are set to the first valve positions so that the lubricant in the mechanical unit 2 can be pumped by the lubricant pump 4 through the sensor module 5 and back via the second control valve 10 in the mechanical unit 2, in order to restore the lubricant circuit for normal operation.

Claims

Claims 1. A method for the automated recalibration of at least one lubricant sensor (51) of a sensor module (5) in a technical system (1) with a mechanical unit (2), wherein the sensor module (5) is arranged in a lubricant circuit with lubricant used by the mechanical unit (2), comprising the following steps: Emptying (S2) at least part of the lubricant circuit (3) so that the sensor module (5) with the at least one lubricant sensor (51) is free of lubricant used by the mechanical unit (2); - Circulating reference lubricant in the lubricant circuit (3) through the sensor module (5); Carrying out at least one reference measurement using the at least one lubricant sensor (51) when the reference lubricant flows through the sensor module (5); Emptying (S8) the lubricant circuit (3) after at least one reference measurement; Filling (S10) the lubricant circuit (3) with lubricant used by the mechanical unit (2); Operating (S10) the technical system (1) with the lubricant used depending on the result of at least one reference measurement.

2. Method according to claim 1, wherein a sensor offset of the at least one lubricant sensor (51) is determined depending on the result of the reference measurement, wherein the sensor offset is used to apply measured variables of the at least one lubricant sensor (51).

3. Method according to claim 1, wherein the at least one lubricant sensor (51) of the sensor module (5) is replaced depending on the result of the reference measurement.

4. Method according to one of claims 1 to 3, wherein the reference measurement is carried out at a plurality of predetermined temperatures, wherein for each plurality of predetermined temperatures and for the at least one lubricant sensor (51) a sensor offset of the at least one lubricant sensor (51) is determined as a function of the result of the reference measurement depending on an initial reference measurement at the relevant temperature, wherein the plurality of sensor offsets are stored in a lookup table or a characteristic curve as a function of the predetermined temperature, wherein the sensor offset for applying the measured variables to the at least one lubricant sensor (51) is determined as a function of the operating temperature of the lubricant.

5. Method according to one of claims 1 to 4, wherein for emptying the lubricant circuit (3) a first control valve (8) and a second control valve (10) are arranged at a first end and a second end of the sensor module (5) respectively, wherein the separation of the lubricant circuit (3) from the mechanical unit (2) takes place by corresponding adjustment of the control valves (8, 10).

6. The method according to any one of claims 1 to 5, wherein the at least one lubricant sensor (51) comprises at least one of the following sensors: a viscosity sensor, a contamination sensor, a compensation temperature sensor, a conductivity sensor, a permittivity sensor, a transmission sensor, an IR sensor (Mid IR and NIR), a relative humidity sensor, an optical particle sensor, an inductive particle sensor and a fluorescence sensor.

7. Method according to one of claims 1 to 6, wherein the reference lubricant is stored in a reference lubricant container (9) from which the reference lubricant is removed to carry out the reference measurement and is returned again after the reference measurement.

8. Method according to one of claims 1 to 6, wherein several reference measurements for calibrating a respective lubricant sensor (51) with different reference lubricants in respective reference lubricant containers (9), from which the respective reference lubricant is taken to carry out the corresponding reference measurement and is returned again after the corresponding reference measurement.

9. Device, in particular control unit, for carrying out a method according to one of claims 1 to 8.

10. Technical system (1) comprising: a mechanical unit (2); a sensor module (5) with at least one lubricant sensor (51); a lubricant pump (4); a lubricant circuit designed to circulate lubricant used in the mechanical unit through the sensor module (5) with the aid of the lubricant pump (4); a valve arrangement for separating the lubricant circuit (3), in which the sensor module (5) is located, from the mechanical unit (2); a control unit (11) designed to control the valve arrangement and the lubricant pump (4) such that o the lubricant circuit (3) is emptied so that the sensor module (5) with the at least one lubricant sensor (51) is free of lubricant used by the mechanical unit (2), o reference lubricant is circulated in the lubricant circuit (3) through the sensor module (5);o At least one reference measurement is carried out using the at least one lubricant sensor (51) when the reference lubricant flows through the sensor module (5); o the lubricant circuit (3) is emptied after the at least one reference measurement; o the lubricant circuit (3) is filled with the lubricant used by the mechanical unit (2); and; the technical system (1) is operated with the lubricant used depending on the result of at least one reference measurement.

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