Planetary transmission

Abstract

Planetary transmission (1) with a housing (2) and at least one planetary stage (3) comprising at least one sun gear (5) provided with a sun gear shaft (6) rotatably mounted in the housing (2), at least one planetary gear support (7) rotatably mounted in the housing (2), at least two planetary gear pins (8) fixed to the planetary gear support (7), on which a planetary gear (9) is respectively rotatably supported, and at least one hollow gear (11) having internal teeth and torsionally fixed within the housing (2), with which the planetary gears (9) are meshed, characterized in that a FOFW system is provided having an interrogation unit (23), at least one antenna (24;30) stationary arranged within the housing (2) and electrically connected to the interrogation unit (23), at least two FOFW sensors (25) fixed to the planetary gear bolts (8), and at least a number of antennas (26) rotating together and fixed to the planetary gear support (7), where such number corresponds to the number of planetary gear bolts (8), which are respectively connected to at least one of the FOFW sensors (25) and are arranged and designed so as to transmit measurement data detected by the FOFW sensors (25) to at least one stationary antenna (24; 30).

Description

Planetary transmission The present invention relates to a planetary transmission with a housing and at least one planetary stage comprising at least one sun gear with a sun gear shaft rotatably mounted in the housing, at least one planetary gear support rotatably mounted in the housing, at least two planetary gear pins fixed to the planetary gear support, each pin supporting a planetary gear in a rotatable manner, and at least one hollow gear having internal teeth and torsionally fixed within the housing, with which the planetary gears mesh. A planetary transmission of this type is known from application DE102011085299A. Planetary transmissions of this type are known in various forms in the prior art.To identify damage in planetary transmissions of this type, condition monitoring systems are normally used, which detect operating data using a wide variety of sensors, where they enable a condition diagnosis, as well as, in a broader context, a statement about the remaining useful life of components or groups of components.The detected operating data can include, for example, bearing temperatures, oil temperatures in the inlet and outlet lines, oil temperatures in the lower transmission housing, vibration values ​​of components along different spatial axes, acoustic emissions in the kilohertz range, particle sizes and / or particle size distributions in oil flows, rotational speeds of individual components, component deformations and / or displacements, rotational torques and / or forces acting on components, rotational oscillations, and similar phenomena, to name just a few examples. The measured variables detected by the sensors are compiled in a data acquisition computer, which then evaluates them against a moving average trend monitor or against pre-set reference values. A fundamental problem in monitoring the condition of planetary gearboxes lies in the fact that, in principle, operating data can be detected easily and inexpensively using stationary sensors. In contrast, applying sensors and measurement technology to rotating machine components is very costly. This requires expensive radio transmission systems that must transmit both the data and the power to the sensors, which in many cases necessitates separate amplifiers or signal processing systems on the rotating components. Furthermore, the damage to be identified is influenced by a multitude of factors, which is why a correspondingly large number of sensors must be installed on the rotating component to detect various operating data.Given the aforementioned circumstances, applications using measurement technology in rotating machine components are currently avoided whenever possible. Based on the aforementioned state of the art, the object of the present invention is to create an alternative planetary transmission of the type indicated in the introduction, which enables simple and economical detection of operating data. To achieve this object, the present invention creates a planetary transmission of the class mentioned in the introduction, characterized in that it provides a FOFW system (a wirelessly interrogatable surface wave sensor system), comprising an interrogation unit, at least one stationary antenna disposed within the housing and electrically connected to the interrogation unit, at least two FOFW sensors (wirelessly interrogatable surface wave sensors) fixed to the planetary gear bolts, and at least a number of antennas that rotate together and are fixed to the planetary gear support, where said number corresponds to the number of planetary gear bolts.These sensors are connected to at least one of the FOFW sensors and are arranged and designed to transmit measurement data detected by the FOFW sensors to at least one stationary antenna. A key advantage of using an FOFW system according to the invention is that the FOFW sensors do not require a separate power source. Therefore, they can be mounted without additional components on the planetary gear pins held in the rotating planetary gear support, which has limited build space. Furthermore, their simple design makes them inexpensive and maintenance-free. They also withstand high thermal and electromagnetic loads, so they can be used without problems in planetary transmissions subjected to high loads. Likewise, both the FOFW sensors,As with the antennas, they can often be retrofitted without major problems, so the FOFW system can also be retrofitted to existing planetary transmissions. Another advantage of using FOFW sensors is that a single FOFW sensor can detect several operating data points, thus eliminating the need for multiple sensors. Overall, the FOFW system according to the invention enables simple and cost-effective detection of relevant planetary gear operating data. According to one embodiment of the present invention, the FOFW system is configured and the FOFW sensors are arranged on the associated planetary gear pins such that, during proper operation of the planetary transmission, at least one of the force components acting on the associated planetary gear pins is detected, and / or an expansion of the planetary gear pin caused in the area of ​​the FOFW sensor, and / or a dominant temperature in the area of ​​the FOFW sensor, and / or a deflection of the planetary gear pin in the area of ​​the FOFW sensor, and / or a rotational speed of the planetary gear carrier. In this way, based on the temperature and / or the rotational speed, forces and torques acting on the planetary gears can be determined, for example. Preferably, the FOFW sensors are positioned within a recess provided in the planetary gear pin and are covered by a support provided on the planetary gear pin, which houses the planetary gear. In this arrangement, the FOFW sensors are protected from external influences. Furthermore, the FOFW sensors can detect not only operating data related to the planetary gear pins but also operating data related to the bearings, such as bearing temperature, which is an essential indicator of bearing performance and wear. Advantageously, several FOFW sensors are mounted along the longitudinal length of each planetary gear pin, preferably electrically connected to a common antenna that rotates together. This allows for the detection of deformations or tilted positions of the planetary gear pins, which have a considerable influence on the load behavior of a planetary gear stage. According to one embodiment of the present invention, the signals emitted by the individual FOFW sensors each have a unique frequency signature, distinguishing them from one another. Such a frequency signature may be inherent to the FOFW sensors. However, it may also be implemented subsequently. Typically, a few megahertz of frequency difference are sufficient in this case to differentiate between the operating data detected by the individual FOFW sensors and the transmitted operating data. According to a first embodiment of the invention, at least one stationary antenna is designed and arranged such that the antennas rotating together, during a rotational movement of the planetary gear support, move sequentially to and from the receiving area of ​​at least one stationary antenna. This results in the operating data detected by the FOFW sensors provided on the respective pins of the planetary gear being transmitted sequentially, and thus referenced to the corresponding pin of the planetary gear, via the associated rotating antenna, to the stationary antenna. Furthermore, by means of the time lag between successive data transmissions, the rotational speed of the planetary gear support can be determined without requiring an additional sensor. Advantageously, the transmission and reception area of ​​the stationary and jointly rotating antennas is smaller than the shortest distance between the jointly rotating antennas. This ensures that FOFW sensors mounted on different pins of the planetary gear cannot transmit their detected data simultaneously, thus guaranteeing sequential data transmission for each pin. According to another alternative embodiment of the present invention, at least one stationary antenna extends essentially in an annular shape at a constant, defined distance from the antennas that rotate together. In this embodiment, the operating data detected by the FOFW sensors are not transmitted sequentially, but continuously. Advantageously, an evaluation unit is provided, connected via data technology to the interrogation unit. This unit is configured to perform calculations based on data detected by the jointly rotating FOFW sensors and transmitted to it. The results of these calculations represent the remaining service life of the planetary gear bolts and / or the planetary gears and / or the planetary gear support when they are fixed, relative to a statistically assured design population. In this way, populations of toothed gears and / or bearings can be created, compensated for temperature, RFC (Rain Flow Count), and / or LDD (Load Dwell Time Curve), to name just one example. Advantageously, the evaluation unit is configured so that, based on the results, specific maintenance intervals are determined. This allows for maintenance tailored to the actual needs. In particular, a temperature-compensated LDD (Linear Dynamic Deviation) can be used here, based on the Arrhenius equation, for planning operating intervals and oil changes. Advantageously, the FOFW system features additional FOFW sensors with associated antennas that rotate together and stationary antennas, where the other FOFW sensors are arranged in the bearing area of ​​the planetary gear support and / or the sun gear shaft. In other words, the FOFW system is designed to detect operating data from other components of the planetary transmission. According to another embodiment of the present invention, at least one FOFW sensor is provided as a reference sensor that detects a rotational torque, which in particular is arranged on the sun gear shaft. In this way, the load distribution between the planetary gears can be determined not only differentially but also absolutely with respect to the reference sensor, thus enabling a statement regarding the load capacity of the transmission. Furthermore, in this way, temporary changes in load behavior, in the sense of transient effects, within the transmission stages can also be detected. To achieve the object mentioned in the introduction, the present invention further suggests using a FOFW system, in particular a FOFW system according to the invention, and an evaluation unit, to determine the remaining useful life of planetary gear bolts and / or planetary gears and / or a planetary gear support of a planetary transmission. Other features and advantages of the present invention are explained by the following description of embodiments of a planetary transmission according to the invention, with reference to the attached drawing. The figures show: Figure 1: a schematic cross-sectional view of a planetary transmission according to a first embodiment of the present invention, which is provided with an FOFW system; Figure 2: A simplified perspective representation of a planetary gear support provided with an FOFW system component, of a first planetary stage of the planetary transmission depicted in Figure 1; Figure 3: A schematic view of the planetary gear support depicted in Figure 2, which shows a deformation of the planetary gear support and of a planetary gear held on it, during the operation of the planetary transmission; Figure 4: A diagram showing planetary gear bolt expansions detected by the FOFW system during a single rotation of the planetary gear carrier, in which the planetary gears are rotatably supported; and Figure 5: A simplified perspective view of the planetary gear support depicted in Figure 2, according to an alternative embodiment of the present invention. Figure 1 shows a planetary transmission 1 according to one embodiment of the present invention. The planetary transmission 1 has a housing 2 in which a first planetary stage 3 and a second planetary stage 4 are arranged. The first planetary stage 3 comprises a sun gear 5 provided on a sun gear shaft 6 rotatably mounted in the housing 2, a planetary gear support 7 mounted in the housing 2, with three planetary gear pins 8 fixed thereto, on which a planetary gear 9 is rotatably supported by a bearing 10, and a hollow gear 11 having internal teeth, torsionally fixed within the housing 2, where the sun gear 5 meshes with the planetary gears 9, which in turn are engaged with the hollow gear 11.The planetary gear support 7 is provided with internal teeth 12 that mesh with a first spur gear 13, which is provided on a second sun gear shaft 14 of the second planetary stage 4, rotatably arranged within the housing 2. A second sun gear 15 is also arranged on the second sun gear shaft 14, which engages with planetary gears 16 of a second planetary gear support 17. These are rotatably supported by bearings 18 on associated planetary gear pins 19. The planetary gears 16 mesh with a second... A hollow gear 20 is torsionally fixed within the housing 2 and has internal teeth. A free end of the second planetary gear support 17 is guided outwards from the housing 2 and is provided with internal teeth 21, by means of which the rotational motion of the second planetary gear support 17 can be transmitted to an external component, not shown in detail. The planetary transmission 1 is equipped with a FOFW system comprising an evaluation unit 22 and an interrogation unit 22 connected to the evaluation unit 22 via data technology. A first stationary antenna 24 is connected to the interrogation unit 23, where said antenna is arranged within the housing 2, contiguous with respect to the first planetary gear support 7. The planetary gear bolts 8 of the first planetary gear support 7 are each provided with three FOFW sensors. 25, which are axially positioned in series in recesses provided in the outer circumference of the planetary gear bolts 8, below the corresponding bearings 10, where they are covered by the bearings. The three FOFW sensors 25 associated with the planetary gear bolts 8 are respectively connected to a common antenna 24 that rotates together, which are arranged at a defined axial distance with respect to the stationary antenna, as represented schematically in Figure 2. The FOFW sensors 25 respectively have a unique natural frequency signature, and are configured so as to detect expansions of the associated planetary gear bolt 8, as well as the temperature in the area of ​​the bearings 10 that house the planetary gears 9.Similarly to the planetary gear bolts 8 of the first planetary gear support 7, the planetary gear bolts 19 of the second planetary gear support 17 are also provided with FOFW sensors 25, which, by means of antennas 26 that rotate together, communicate via data technology with a stationary antenna 24 that is connected to the interrogation unit 23. In addition, the FOFW system comprises a reference sensor 27 also designed as an FOFW sensor, which is arranged on the sun gear shaft 6 and is connected to a jointly rotating antenna 28, held on the sun gear shaft 6, which communicates with another stationary antenna 29 that is connected to the interrogation unit 23, where the reference sensor 27 detects a rotational torque acting on the sun gear shaft 6, which is used as a reference. During the operation of planetary transmission 1, the jointly rotating antennas 26, 28 each pass one position in front of the associated stationary antenna 24, 29 with each rotation. As they pass in front of it, the FOFW sensors 25, 27 enter the transmission / reception area of ​​the associated stationary antenna 24, 29 and are interrogated. The antennas then detect their measurement values ​​and transmit them to the evaluation unit 22. The FOFW sensors 25, arranged on the pins of the planetary gear 8, 19, detect measurement values ​​representing the deformations of the individual pins of the planetary gear 8, 19, as shown in Figures 3 and 4. Figure 3 shows the deformation of an individual pin of the planetary gear 8 under load. Figure 4 shows the detected deformations of the three planetary gear bolts 8 after one rotation of the first planetary gear support 7.Furthermore, the FOFW 25 sensors provide measurement values ​​representing the current temperature in the bearing area 10, 18. Based on the time intervals and the order in which the consecutive FOFW 25 sensors on the planetary gear pins 8, 19 transmit their measurement values, the current direction of rotation and current rotational speed of the planetary gear supports 7, 17 are calculated in the evaluation unit 22. Based on these values, the evaluation unit 22 thus enables the creation of temperature-compensated, rotational speed-based RFC populations, and in particular, bearing and gear LDD populations. Additionally, a target-to-actual comparison of the records used to evaluate component life (RFC, LDD, load cycle limits, temperature load) can be used for service planning or damage prediction. Figure 5 shows as an example an alternative annular embodiment of a stationary antenna 30. In this variant, the individual FOFW 25 sensors can be interrogated permanently, since they are always in the transmission / reception area of ​​the stationary antenna 30. Although the invention has been illustrated and described in detail through the preferred embodiment, the present invention is not limited to the described examples, so that a person skilled in the art may deduce other variations based on them without leaving the scope of protection of the invention. Thus, the number of FOFW sensors arranged on a pin of an individual planetary gear, the number of stationary antennas and / or antennas that rotate together, or similar variations, can be varied, to name just a few examples.

Claims

1. A planetary transmission (1) with a housing (2) and at least one planetary stage (3) comprising at least one sun gear (5) provided with a sun gear shaft (6) rotatably mounted in the housing (2), at least one planetary gear support (7) rotatably mounted in the housing (2), at least two planetary gear pins (8) fixed in the planetary gear support (7), on which a planetary gear (9) is respectively rotatably supported, and at least one hollow gear (11) having internal teeth and torsionally fixed within the housing (2), with which the planetary gears (9) are meshed, characterized in that a FOFW system is provided having an interrogation unit (23), at least one stationary antenna (24; 30) disposed within the housing (2) and electrically connected to the interrogation unit (23),at least two FOFW sensors (25) fixed to the planetary gear bolts (8), and at least a number of antennas (26) rotating together and fixed to the planetary gear support (7), where such number corresponds to the number of planetary gear bolts (8), which are respectively connected to at least one of the FOFW sensors (25) and are arranged and designed so as to transmit measurement data detected by the FOFW sensors (25) to at least one stationary antenna (24; 30).

2. Planetary transmission (1) according to claim 1, characterized in that the FOFW system is configured and the FOFW sensors (25) are arranged on the associated planetary gear pins (8) such that during proper operation of the planetary transmission (1) at least one of the force components acting on the associated planetary gear pins (8) is detected,and / or an expansion of the planetary gear pin (8) caused in the area of ​​the FOFW sensor (25) and / or a dominant temperature in the area of ​​the FOFW sensor (25) and / or a flexure of the planetary gear pin (8) in the area of ​​the FOFW sensor (25) and / or a rotational speed of the planetary gear support (7).

3. Planetary transmission (1) according to any of the preceding claims, characterized in that the FOFW sensors (25) are positioned within a recess provided in the planetary gear pin (8) and are covered by a support (10) provided on the planetary gear pin (8), which houses the planetary gear (9).

4. Planetary transmission (1) according to any of the preceding claims, characterized in that several FOFW sensors (25) are fixed along the longitudinal extension of each planetary gear pin (8),which are preferably electrically connected to a common antenna (28) that rotates together.

5. Planetary transmission (1) according to any of the preceding claims, characterized in that the signals emitted by the individual FOFW sensors (25) each have a unique frequency signature.

6. Planetary transmission (1) according to any of the preceding claims, characterized in that at least one stationary antenna (24) is designed and arranged such that the antennas (26) that rotate together, during a rotational movement of the planetary gear support (7), move one after the other to and from the receiving area of ​​at least one stationary antenna (24).

7. Planetary transmission (1) according to claim 6, characterized in that the transmission and receiving areas of the stationary and jointly rotating antennas (24,28) is smaller than the shortest distance between the jointly rotating antennas (28).

8. Planetary transmission (1) according to any one of claims 1 to 5, characterized in that at least one stationary antenna (30) extends essentially in an annular shape at a constant, defined distance from the jointly rotating antennas (28).

9. Planetary transmission (1) according to any one of the preceding claims, characterized in that an evaluation unit (22) connected via data technology to the interrogation unit (23) is provided, which is configured such that, based on the data detected by the jointly rotating FOFW sensors (25) and transmitted to the interrogation unit (23), it performs calculations,whose results represent a remaining service life of the planetary gear bolts (8) and / or the planetary gears (9) and / or the planetary gear support (7).

10. Planetary transmission (1) according to claim 9, characterized in that the evaluation unit (23) is configured so that, based on the results, maintenance intervals are determined.

11. Planetary transmission (1) according to any of the preceding claims, characterized in that the FOFW system comprises other FOFW sensors with associated antennas that rotate together and stationary antennas, wherein the other FOFW sensors are arranged in the bearing area of ​​the planetary gear support and / or the sun gear shaft.

12. Planetary transmission (1) according to any of the preceding claims, characterized in that at least one FOFW sensor is provided as a reference sensor (27) that detects a rotational torque,which in particular is arranged on the sun gear shaft (6).

13. Use of a FOFW system and an evaluation unit to determine the remaining service life of 5 planetary gear bolts (8, 19) and / or planetary gears (9, 16) and / or a planetary gear support (7, 17) of a planetary transmission (1).

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