Sensor device for detecting vibrations

Abstract

A sensor device (1) for detecting vibrations, comprising an optical sensor (6) and an inductive sensor (5).

Description

2024PF00002 1 Description TITLE Sensor device for detecting vibrations TECHNICAL AREA

[0001] The invention relates to a sensor device for detecting vibrations.

[0002] Such sensor devices are used, for example, in turbomachinery such as steam turbines. A steam turbine, as a type of turbomachine, essentially consists of a rotatably mounted rotor and a casing arranged around the rotor. The thermal energy of steam is converted into mechanical energy, with turbine blades playing a crucial role in this process. During operation, the turbine blades can vibrate. However, excessive vibrations can lead to malfunctions of the turbine blades. Therefore, these vibrations are typically measured and monitored.

[0003] Sensors, such as optical and / or inductive sensors, are used for this purpose. The so-called tip-timing method is well-known. Tip-timing sensors are used to monitor vibrations in rotating systems. Based on the calculated deflection of a turbine blade, the operating range within which a measured row of rotor blades can be safely operated is determined.

[0004] For this purpose, the calculated deflection is compared with the permissible deflection. A safety factor is incorporated into the calculated deflection to conservatively account for uncertainties in the deflection calculation. This safety factor includes an estimate of the uncertainty resulting from measurements of steam turbine blades during operation using inductive sensors. 2024PF00002 2

[0005] The uncertainty of optical sensors is typically lower than that of inductive sensors. Ideally, to minimize this uncertainty, all measurements would be performed with optical sensors. However, this is not feasible because, depending on environmental conditions (particles / droplets in the flow medium), optical sensors may not provide usable results, the sensor ages rapidly, and its measurement capability is thereby limited. Inductive sensors, on the other hand, are significantly less sensitive to medium influences. Therefore, to reduce conservative assumptions and expand the operating range, a calibration standard is required.

[0006] Since the uncertainty in the measurement with an inductive sensor depends on various environmental parameters such as the operating point-dependent distance from the blade tip to the sensor, the induced voltage and the blade magnetization, this calibration can only be carried out in the field during operation and is potentially also load point-dependent. BACKGROUND

[0007] It is known to install strain gauges on turbine blades. However, this approach is comparatively expensive, requires major modifications to the machine, and also has a short lifespan. Furthermore, it usually needs to be removed during commissioning. The use of strain gauges in turbines or compressors is therefore limited.

[0008] It would be desirable to have a device that allows for reliable measurement of vibrations. SUMMARY OF THE INVENTION

[0009] This is where the invention comes in, and the object of the invention is to provide a sensor device with which vibrations can be reliably detected. 2024PF00002 3

[0010] This task is solved by a sensor device for detecting vibrations, comprising an optical sensor and an inductive sensor.

[0011] It is therefore proposed to use a combined optical and inductive sensor.

[0012] Such a new sensor device, which could also be called a hybrid sensor, makes it possible to reduce the complexity of the measurement chain without incurring significant additional costs. For each flow of a turbomachine, the hybrid sensor can simply be installed in one of the standard sensor bores instead of the otherwise used inductive sensor, resulting in cost savings.

[0013] Advantageous embodiments are the subject of the dependent claims.

[0014] The dependent claims list further advantages that can be combined in any way to achieve further advantages. DESCRIPTION OF THE INVENTION

[0015] A key aspect of the invention is that the sensor device now comprises both an inductive sensor and an optical sensor which are arranged close together locally.

[0016] In a first advantageous embodiment, several optical sensors are arranged around the inductive sensor. In other words, the sensor device has an inductive sensor core surrounded by several optical sensors. [00171 In a further advantageous embodiment, the optical sensors are arranged in a circle around the inductive sensor.

[0018] Advantageously, the optical sensors are arranged at equidistant intervals on the circular path. 2024PF00002 4

[0019] In an advantageous further development, exactly five optical sensors are arranged in the sensor device.

[0020] In an advantageous further development, the inductive sensor and the optical sensors are arranged in a common housing.

[0021] With the sensor device according to the invention, the axial position of the sensor relative to the turbine blade can be determined when correctly aligned, and optical measurements can simultaneously be taken at the same axial position and directly in front of and behind the circumferential position of the inductive sensor in its immediate vicinity. In this way, the uncertainty in the inductive measurement during commissioning can be minimized over a large operating range, and vibrations can be continuously monitored using the derived calibration factors. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] An embodiment of the invention will be explained in more detail below with reference to the following figures.

[0023] The properties, features and advantages of this invention described above, as well as the manner in which they are achieved, will become clearer and more easily understood in connection with the following description of the exemplary embodiments, which are explained in more detail in conjunction with the drawings.

[0024] Identical components or components with the same function are marked with the same reference numerals.

[0025] Exemplary embodiments of the invention are described below with reference to the drawings. These drawings are not intended to be drawn to scale; rather, where helpful for explanation, they are presented in a schematic and / or slightly distorted form. For further details regarding the teachings directly apparent from the drawings, reference is made to the relevant prior art. 2024PF00002 5

[0026] They show:

[0027] FIG 1 a schematic side view of a sensor view according to the invention

[0028] FIG 2 shows a schematic representation of the sensor device

[0029] FIG 2 a perspective view of the sensor device DESCRIPTION OF THE EXECUTION FORMS

[0030] Figure 1 shows a schematic representation of a sensor device 1 according to the invention.

[0031] The sensor device 1 comprises a housing 2, which is inserted into an inner casing of a turbomachine (not shown). The sensor device 1 includes a sensor head 3 with a front plate 4, which, when installed, should be positioned as close as possible to the blades to be measured. The sensor head 3 and the housing 2 are cylindrical, so that only a suitable bore is required in the inner casing.

[0032] An inductive sensor 5 and several optical sensors 6 protrude from the front plate 4 or are flush with the front plate 4. The arrangement of the inductive sensor 5 and the optical sensors 6 is not shown in Figure 1. The position and arrangement of the inductive sensor 5 and the optical sensors 6 are described in more detail in Figures 2 and 3.

[0033] The signals detected by the inductive sensor 5 and the optical sensors 6 during operation are transmitted via suitable signal lines 7 and processed in suitable evaluation units (not shown).

[0034] Figure 2 shows a front view of the sensor device 1. The front plate 4 of the sensor head 3 is visible in this illustration. The arrangement of the optical sensors 6 is formed around an inductive sensor 5. The inductive sensor 5 is arranged in a central position and the 2024PF00002 6 optical sensors 6 are arranged on a circular path 8 around the inductive sensor 5.

[0035] The distribution of the optical sensors 6 is symmetrical as shown in Figure 2. There is one optical sensor 6 in the 6 o'clock position, one optical sensor 6 in the 3 o'clock position, one optical sensor 6 in the 9 o'clock position, and two optical sensors 6 in the 11 o'clock and 1 o'clock positions, respectively. [003SJ In an alternative embodiment, the optical sensors 6 can also be arranged at equidistant intervals on the circular path.

[0037] Figure 3 shows a perspective view of the sensor device 1. It is clearly visible that the inductive sensor 5 and the optical sensors 6 are arranged in a housing 2. Suitable holes are provided in the front plate 4, into which the inductive sensor 5 and the optical sensors 6 are mounted.

[0038] Although the invention has been illustrated and described in detail by the preferred embodiment, the invention is not limited by the disclosed examples and other variants can be derived by a person skilled in the art without leaving the scope of protection of the invention.

Claims

2024PF00002 7 Claims 1. Sensor device (1) for detecting vibrations comprising an optical sensor (6) and an inductive sensor (5).

2. Sensor device (1) according to claim 1, with several optical sensors (6) arranged around the inductive sensor (5).

3. Sensor device (1) according to claim 2, wherein the optical sensors (6) are arranged circularly around the inductive sensor (5).

4. Sensor device (1) according to claim 3, wherein the optical sensors (6) have equidistant distances to each other on the circular path (8).

5. Sensor device (1) according to claim 2, 3 or 4, wherein the number of optical sensors (6) is exactly five.

6. Sensor device (1) according to one of the preceding claims, wherein the inductive sensor (5) and the optical sensor (6) are arranged in a common housing (2).

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