WO2016119949A1 - Wireless bearing monitoring device - Google Patents

Wireless bearing monitoring device Download PDF

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Publication number
WO2016119949A1
WO2016119949A1 PCT/EP2015/078294 EP2015078294W WO2016119949A1 WO 2016119949 A1 WO2016119949 A1 WO 2016119949A1 EP 2015078294 W EP2015078294 W EP 2015078294W WO 2016119949 A1 WO2016119949 A1 WO 2016119949A1
Authority
WO
WIPO (PCT)
Prior art keywords
antenna
frequency range
bearing
monitoring device
bearing monitoring
Prior art date
Application number
PCT/EP2015/078294
Other languages
French (fr)
Inventor
Gertjan Van Amerongen
Nicolaas DEN HAAK
Bart Hiddink
Original Assignee
Aktiebolaget Skf
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Aktiebolaget Skf filed Critical Aktiebolaget Skf
Publication of WO2016119949A1 publication Critical patent/WO2016119949A1/en

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M13/00—Testing of machine parts
    • G01M13/04—Bearings
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C33/00—Parts of bearings; Special methods for making bearings or parts thereof
    • F16C33/72—Sealings
    • F16C33/76—Sealings of ball or roller bearings
    • F16C33/78—Sealings of ball or roller bearings with a diaphragm, disc, or ring, with or without resilient members
    • F16C33/7803—Sealings of ball or roller bearings with a diaphragm, disc, or ring, with or without resilient members suited for particular types of rolling bearings
    • F16C33/7806—Sealings of ball or roller bearings with a diaphragm, disc, or ring, with or without resilient members suited for particular types of rolling bearings for spherical roller bearings
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C35/00—Rigid support of bearing units; Housings, e.g. caps, covers
    • F16C35/04—Rigid support of bearing units; Housings, e.g. caps, covers in the case of ball or roller bearings
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C41/00—Other accessories, e.g. devices integrated in the bearing not relating to the bearing function as such
    • F16C41/008—Identification means, e.g. markings, RFID-tags; Data transfer means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C43/00—Assembling bearings
    • F16C43/04—Assembling rolling-contact bearings
    • G—PHYSICS
    • G08—SIGNALLING
    • G08C—TRANSMISSION SYSTEMS FOR MEASURED VALUES, CONTROL OR SIMILAR SIGNALS
    • G08C17/00—Arrangements for transmitting signals characterised by the use of a wireless electrical link
    • G—PHYSICS
    • G08—SIGNALLING
    • G08C—TRANSMISSION SYSTEMS FOR MEASURED VALUES, CONTROL OR SIMILAR SIGNALS
    • G08C17/00—Arrangements for transmitting signals characterised by the use of a wireless electrical link
    • G08C17/02—Arrangements for transmitting signals characterised by the use of a wireless electrical link using a radio link
    • G—PHYSICS
    • G08—SIGNALLING
    • G08C—TRANSMISSION SYSTEMS FOR MEASURED VALUES, CONTROL OR SIMILAR SIGNALS
    • G08C25/00—Arrangements for preventing or correcting errors; Monitoring arrangements
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q1/00—Details of, or arrangements associated with, antennas
    • H01Q1/12—Supports; Mounting means
    • H01Q1/22—Supports; Mounting means by structural association with other equipment or articles
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C19/00—Bearings with rolling contact, for exclusively rotary movement
    • F16C19/22—Bearings with rolling contact, for exclusively rotary movement with bearing rollers essentially of the same size in one or more circular rows, e.g. needle bearings
    • F16C19/34—Bearings with rolling contact, for exclusively rotary movement with bearing rollers essentially of the same size in one or more circular rows, e.g. needle bearings for both radial and axial load
    • F16C19/38—Bearings with rolling contact, for exclusively rotary movement with bearing rollers essentially of the same size in one or more circular rows, e.g. needle bearings for both radial and axial load with two or more rows of rollers
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C2233/00—Monitoring condition, e.g. temperature, load, vibration
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C23/00—Bearings for exclusively rotary movement adjustable for aligning or positioning
    • F16C23/06—Ball or roller bearings
    • F16C23/08—Ball or roller bearings self-adjusting
    • F16C23/082—Ball or roller bearings self-adjusting by means of at least one substantially spherical surface
    • F16C23/086—Ball or roller bearings self-adjusting by means of at least one substantially spherical surface forming a track for rolling elements
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C33/00—Parts of bearings; Special methods for making bearings or parts thereof
    • F16C33/72—Sealings
    • F16C33/76—Sealings of ball or roller bearings
    • F16C33/78—Sealings of ball or roller bearings with a diaphragm, disc, or ring, with or without resilient members
    • F16C33/784—Sealings of ball or roller bearings with a diaphragm, disc, or ring, with or without resilient members mounted to a groove in the inner surface of the outer race and extending toward the inner race
    • F16C33/7843—Sealings of ball or roller bearings with a diaphragm, disc, or ring, with or without resilient members mounted to a groove in the inner surface of the outer race and extending toward the inner race with a single annular sealing disc
    • F16C33/7853—Sealings of ball or roller bearings with a diaphragm, disc, or ring, with or without resilient members mounted to a groove in the inner surface of the outer race and extending toward the inner race with a single annular sealing disc with one or more sealing lips to contact the inner race
    • F16C33/7856—Sealings of ball or roller bearings with a diaphragm, disc, or ring, with or without resilient members mounted to a groove in the inner surface of the outer race and extending toward the inner race with a single annular sealing disc with one or more sealing lips to contact the inner race with a single sealing lip
    • G—PHYSICS
    • G08—SIGNALLING
    • G08C—TRANSMISSION SYSTEMS FOR MEASURED VALUES, CONTROL OR SIMILAR SIGNALS
    • G08C2200/00—Transmission systems for measured values, control or similar signals

Definitions

  • the invention relates to a wireless bearing monitoring device and to a bearing equipped with such a device.
  • the bearing monitoring device should fit into standard bearing dimensions and be able to operate in close proximity voluminous parts of steel or of lubricant.
  • Steel casings of the bearing will act as Faraday cages, completely blocking RF signals.
  • the steel parts will produce reflections which might cause intersymbol interference in time and degrade communication performance.
  • Steel parts that are within a quarter wavelength will detune the antenna.
  • the same accounts for grease and oil.
  • the inventors have observed a big detuning of the antenna especially due to grease and oil. Further, the grease/oil in close proximity to the antenna will dampen the radio waves, reducing the range. Tolerances and non-perfect running conditions like misalignment will dynamically influence the antenna's performance.
  • Such antennae should also meet the need of scalability and cascadability due to the various sizes and types of bearings needed.
  • the device should be suitable for integration into standard bearings for which the environment is difficult to predict.
  • the antenna design should therefore be particularly robust against changes of the environment. The difficulty of finding a suitable antenna is further increased, as limited experience is available with the use of steel enclosures in combination with oil or grease.
  • the document WO 2010015231 A1 discloses a bearing monitoring device including patch antenna which is associated with the body of the bearing component and which is disposed on the bearing holder.
  • the patch antenna interacts a RFID-tag that is disposed on the bearing.
  • Said bearing component and/or said bearing arrangement according to WO 20100015231 A1 solve the problem of providing a bearing component and/or a bearing arrangement having an antenna that is advantageous for polling by way of electromagnetic radiation.
  • US 20100283208A1 discloses a sealing element of a bearing carrying an IC element and an antenna.
  • the invention seeks to overcome the above problems and to provide a bearing monitoring device including a sensor assembly with a reliable wireless communication means in order to enable a robust and reliable communication between a sensorized bearing equipped with the bearing monitoring device and a network even under harsh environments.
  • the invention relates to a bearing monitoring device including a sensor assembly configured be mounted on a cover member of a bearing.
  • the cover member shall cover the roller space accommodating rolling elements of the bearing.
  • the rolling elements may be rollers, balls or needles of any kind.
  • the cover member may in particular be a seal or a metal capping ring arranged radially between an inner ring and an outer ring of the bearing.
  • the bearing monitoring device includes a wireless transmitter for transmitting and receiving data relating to the operation of the sensor assembly in a predetermined frequency range, wherein the wireless transmitter includes at least one antenna.
  • the antenna has a rated frequency range, wherein a lower limit frequency of the rated frequency range is higher than an upper limit frequency of the predetermined frequency range.
  • the inventors have found that the selection of a rated frequency range according to the invention leaves room for and accounts for the typical detuning experienced once the antenna is mounted in the sensor bearing and the sensor bearing is mounted in its application. Extensive experimentation has uncovered that the signal quality is sufficiently high although the signals are strongly influenced by the environment.
  • Wireless sensor assemblies are particularly suitable for applications where the assembly and the bearing cover member is mounted on the rotating ring of the bearing.
  • applications where wireless technology is advantageous for devices attached to the non-rotating ring of the bearing may exist as well.
  • the rated frequency range may be defined as the frequency range within which the voltage standing wave ratio (VSWR) is 1 .1 or less.
  • the rated frequency range is determined in a neutral environment prior to mounting the antenna to the bearing or to the bearing monitoring device.
  • the lower limit frequency of the rated frequency range is at least 10%, or even at least 20% higher than the upper limit frequency of the predetermined frequency range. This leaves sufficient room even for strong detuning.
  • it is proposed rated frequency range of the antenna is wider than the predetermined frequency range
  • the predetermined frequency range is one of the ISM bands defined by the ITU- R in 5.138, 5.150, and 5.280 of the Radio Regulations, most preferably the frequency range between 2.4GHz and 2.5GHz.
  • the antenna has a rated frequency range between 3.1 and 5 GHz.
  • the bandwidth should preferably amount to 1 .9 GHz or more.
  • the antenna is a chip antenna for Ultra Wideband (UWB) applications. These antenna chips are available on the market for wireless USB. Extensive experimentation has uncovered that these antenna chips are sufficiently robust for use in sensor bearing applications.
  • UWB Ultra Wideband
  • the cover is a metal ring having at least one window for the antenna.
  • the metal ring is preferably configured to cover the roller chamber and the antenna is preferably mounted on the inner side of the metal ring, i.e. the side facing the rollers.
  • the bearing is grease lubricated.
  • the antenna design according to the invention is highly robust against influences of large volumes of lubricant in close proximity to the bearing.
  • the antenna is mounted on board with a clearance zone, i.e. a PCB zone without ground plate beneath the antenna. Accordingly, the ground plate cannot reflect or screen the signal transmitted by the antenna.
  • the antenna could be mounted next to the board and connected to the transceiver e.g. by a coaxial cable.
  • the inventors further propose that the antenna is mounted on board having a feed trace structure on the side opposite to the side of the antenna. This arrangement avoids close proximity between the feed structure and the cover member through which the antenna protrudes.
  • said cover member has a radial width of 13.5 mm or less.
  • the antenna is preferably configured to be accommodated within space of less than 7 mm between cover member and rollers.
  • the inventors further propose that no LC matching circuit is provided for matching the frequency bandwidth of the antenna.
  • the LC matching cirquit would impair the overall Q factor of the network and it has turned out that the typical steel and grease environment is sufficient for matching the antenna.
  • a further aspect of the invention relates to a bearing including a bearing monitoring device as described above.
  • the bearing is a spherical roller bearing.
  • the varying environment of the spherical roller bearing requires a particular degree of insensitivity against changes of the environment, which is what the invention provides.
  • the invention combines fractal antenna technology with bearings.
  • the preferred fractal antenna is ultra wide band optimized for a rated frequency range between 3 - 6 GHz, which allows for the big detuning caused by the presence of grease/oil.
  • the antenna is designed to fit in a steel cover that is mounted to the side of the bearing. Due to the large bandwidth (frequency range) of the fractal antenna, the inventors suggest a well defined "de-tuning" by design, i.e. in one of the designs the direct environment of the antenna will be controlled by encapsulation / potting of the antenna. The detuning by the controlled direct environment will shift the frequency range of the antenna from the rated frequency range to a range overlapping with the predetermined frequency range required by the application.
  • Fig. 1 illustrates a bearing equipped with a bearing monitoring device ac- cording to the invention
  • Fig. 2 illustrates a circuit board for use in a bearing monitoring device according to Fig. 1 .
  • Fig. 1 illustrates schematically a grease lubricated spherical roller bearing having an inner ring 10, an outer ring 12 and plural rolling elements 14 formed as rollers arranged in a cage 16 between the inner ring 10 and the outer ring 12.
  • the rollers 14 are protected by a cover member 18 formed as a metal capping ring.
  • the system is a sensor bearing equipped with a bearing monitoring device including a sensor assembly 20 configured be mounted on the inside of the cover member 18 of a bearing or in a recess/window of the cover member 18.
  • the sensor assembly 20 includes a wireless RF transceiver (not shown) for transmitting and receiving data relating to the operation of the sensor assembly in a predetermined frequency range which is a frequency range of a receiver 21 located roughly 1 m away from the bearing, wherein the wireless transceiver includes at least one antenna 22.
  • the sensor assembly 20 further includes one or multiple sensors formed e.g. as temperature sensor, vibration sensor, acoustic emission sensor or probe for measuring the chemical properties of lubricant (not shown).
  • the sensor assembly 20 may optionally include power harvesting means or a battery for operating the wireless transmitter (not shown).
  • the antenna 22 has a rated frequency range, wherein a lower limit frequency of the rated frequency range is higher than an upper limit frequency of the predetermined frequency range.
  • the predetermined frequency range is the ISM band between 2.4GHz and 2.5GHz and the antenna is formed as a fractal SMD antenna chip for Ultra Wideband (UWB) applications having a rated frequency range between 3.1 and 5 GHz.
  • the lower limit frequency of the rated frequency range is roughly 20% higher than the upper limit frequency of the predetermined frequency range.
  • the cover member 18 / metal ring has at least one window 24 for the antenna 22 and the antenna chip is embedded into the window 24 such that the axially outer surface of the capping is essentially flat, i.e. that the antenna 22 does not protrude over the axially outer surface.
  • the antenna 22 is quadratic with edges of 10 mm length and the window 24 is quadratic with edges of 13 mm length.
  • the clearance between the antenna and the edges of the window has a width amounting to 30% of the length of the edges of the antenna 22 and is filled with potting material 26.
  • the potting material 26 is selected based on its RF properties, i.e. is a RF controlled material.
  • Fig. 2 illustrates a printed circuit board 30 with an antenna 22 mounted thereon.
  • a clearance zone (not illustrated) without ground plate is located beneath the antenna 22.
  • a feed trace structure 28 is illustrated in dashed lines and arranged on the side facing the rollers 14 opposite to the side of the antenna 22.
  • the board 30 has a curved shape adapted to the curvature of the cover member.
  • the board has a radial width of 13.5 mm and spans about 40degrees in a circumferential direction of the cover ring 18.
  • the antenna 22 is configured to be accommodated within an axial space of less than 7 mm between cover member 18 and rollers. 14
  • the height of the assembly in Fig. 2 perpendicular to the drawing plane is therefore 7 mm or less.
  • the board 30 (equipped with further electronic devices and/or sensors as desired) is fixed to the cover member 18 by a nylon screw and potted in order to protect the devices mounted on it.
  • the invention combines ultra high bandwith leading to insensitivety for the presence of grease/oil and metal and different geometries from bearing types/sizes with an impoved sensor cap design for achieving a controlled de- tuning by shaping the environment, and protection of a sensitive element from mechanical impacts.
  • the invention provides a wireless antenna 22 that can be integrated into a bearing end-cap or seal.
  • This antenna design enables wireless data transmission in harsh environments that are common to bearing applications.
  • the inventors have tested the device according to the invention for a bearing with 100 mm inner ring diameter and found a sufficient matching for a large variety of operating conditions including grease volumes at different locations for the 2.4 GHz frequency band.

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Rolling Contact Bearings (AREA)

Abstract

The invention relates to a bearing monitoring device including a sensor assembly (20) configured be mounted on a cover member (18) of a bearing and a wireless transmitter for transmitting and receiving data relating to the operation of the sensor assembly (20) in a predetermined frequency range, wherein the wireless transmitter includes at least one antenna (22). In order to account for detuning due to lubricant and steel in the environment of the antenna (22), the antenna (22) has a rated frequency range, wherein a lower limit frequency of the rated frequency range is higher than an upper limit frequency of the predetermined frequency range.

Description

Title
Wireless Bearing Monitoring Device
Field of the Invention
The invention relates to a wireless bearing monitoring device and to a bearing equipped with such a device. Background of the Invention
It is known to provide rotating parts of bearings with bearing monitoring systems including a wireless transmitter. In some applications, the transmitter and its antenna are located remote from the bearing in order to avoid a degradation of the radio signals. When trying to integrate wireless systems into universally applicable bearings with standard dimensions, it is necessary to respect the boundary dimensions and to integrate the antenna into the bearing unit. Due to the small available space, the solid and moving metal parts and grease in close proximity to the possible locations of the antenna and the harsh environmental conditions, it has been difficult to make an antenna to meet the requirements. In typical applications, the receiver will be placed at a distance of one or more meters and the attenuation of the signal should not exceed a certain threshold depending on the application. It has turned out to be very difficult to find suitable antennae for use in bearing cover elements. The bearing monitoring device should fit into standard bearing dimensions and be able to operate in close proximity voluminous parts of steel or of lubricant. In these harsh environments there are multiple factors that impact antenna performance. Steel casings of the bearing will act as Faraday cages, completely blocking RF signals. In addition, the steel parts will produce reflections which might cause intersymbol interference in time and degrade communication performance. Steel parts that are within a quarter wavelength will detune the antenna. The same accounts for grease and oil. The inventors have observed a big detuning of the antenna especially due to grease and oil. Further, the grease/oil in close proximity to the antenna will dampen the radio waves, reducing the range. Tolerances and non-perfect running conditions like misalignment will dynamically influence the antenna's performance. In addition to the above, such antennae should also meet the need of scalability and cascadability due to the various sizes and types of bearings needed. The device should be suitable for integration into standard bearings for which the environment is difficult to predict. The antenna design should therefore be particularly robust against changes of the environment. The difficulty of finding a suitable antenna is further increased, as limited experience is available with the use of steel enclosures in combination with oil or grease.
The document WO 2010015231 A1 discloses a bearing monitoring device including patch antenna which is associated with the body of the bearing component and which is disposed on the bearing holder. The patch antenna interacts a RFID-tag that is disposed on the bearing. Said bearing component and/or said bearing arrangement according to WO 20100015231 A1 solve the problem of providing a bearing component and/or a bearing arrangement having an antenna that is advantageous for polling by way of electromagnetic radiation.
The document US 20100283208A1 discloses a sealing element of a bearing carrying an IC element and an antenna.
The miniaturization of antennae has made enormous progress in the last years. Noteworthy developments include fractal antennae as disclosed in the US patent No. 9501019 and multilevel antennae as disclosed in the document
EP 1 223 637 A1 . Fractal antennae or generally antennae with self-similar geometries having self-similar elements in different orders of magnitude lend themselves to operate in multiple frequency ranges which can be combined to form a single ultra-wide frequency band (UWB) while being compact in design and may be integrated in a small SMD chip with dimensions of approximately 10mm x 10mm. An example of an antenna chip of this kind is UWB chip antenna FR-05-S1 -P-0-107 available from Fractus S.A., Barcelona, Spain. The intended field of application for this antenna is Wireless USB for mobile phones or other handheld high-tech devices. The applicability to mechanical devices operating under harsh environmental conditions has hitherto been considered impossible due to the sensitivity and fragility of these devices. Summary of the Invention
The invention seeks to overcome the above problems and to provide a bearing monitoring device including a sensor assembly with a reliable wireless communication means in order to enable a robust and reliable communication between a sensorized bearing equipped with the bearing monitoring device and a network even under harsh environments. The invention relates to a bearing monitoring device including a sensor assembly configured be mounted on a cover member of a bearing. The cover member shall cover the roller space accommodating rolling elements of the bearing. The rolling elements may be rollers, balls or needles of any kind. The cover member may in particular be a seal or a metal capping ring arranged radially between an inner ring and an outer ring of the bearing.
The bearing monitoring device includes a wireless transmitter for transmitting and receiving data relating to the operation of the sensor assembly in a predetermined frequency range, wherein the wireless transmitter includes at least one antenna.
It is proposed that the antenna has a rated frequency range, wherein a lower limit frequency of the rated frequency range is higher than an upper limit frequency of the predetermined frequency range. The inventors have found that the selection of a rated frequency range according to the invention leaves room for and accounts for the typical detuning experienced once the antenna is mounted in the sensor bearing and the sensor bearing is mounted in its application. Extensive experimentation has uncovered that the signal quality is sufficiently high although the signals are strongly influenced by the environment.
Wireless sensor assemblies are particularly suitable for applications where the assembly and the bearing cover member is mounted on the rotating ring of the bearing. However, applications where wireless technology is advantageous for devices attached to the non-rotating ring of the bearing may exist as well.
Here and in the following, the rated frequency range may be defined as the frequency range within which the voltage standing wave ratio (VSWR) is 1 .1 or less. The rated frequency range is determined in a neutral environment prior to mounting the antenna to the bearing or to the bearing monitoring device.
Preferably, the lower limit frequency of the rated frequency range is at least 10%, or even at least 20% higher than the upper limit frequency of the predetermined frequency range. This leaves sufficient room even for strong detuning. In order to account for a decrease of the bandwidth as it is typically entailed by the detuning, it is proposed rated frequency range of the antenna is wider than the predetermined frequency range
The predetermined frequency range is one of the ISM bands defined by the ITU- R in 5.138, 5.150, and 5.280 of the Radio Regulations, most preferably the frequency range between 2.4GHz and 2.5GHz. According to a further aspect of the invention, it is proposed that the antenna has a rated frequency range between 3.1 and 5 GHz. The bandwidth should preferably amount to 1 .9 GHz or more. Preferably, the antenna is a chip antenna for Ultra Wideband (UWB) applications. These antenna chips are available on the market for wireless USB. Extensive experimentation has uncovered that these antenna chips are sufficiently robust for use in sensor bearing applications.
In a preferred embodiment of the invention, the cover is a metal ring having at least one window for the antenna. The metal ring is preferably configured to cover the roller chamber and the antenna is preferably mounted on the inner side of the metal ring, i.e. the side facing the rollers.
In a preferred embodiment of the invention, the bearing is grease lubricated. The advantages of the invention are particularly clear in this case because extensive experimentation has uncovered that the antenna design according to the invention is highly robust against influences of large volumes of lubricant in close proximity to the bearing. According to a further aspect of the invention, it is proposed that the antenna is mounted on board with a clearance zone, i.e. a PCB zone without ground plate beneath the antenna. Accordingly, the ground plate cannot reflect or screen the signal transmitted by the antenna. In alternative embodiments, the antenna could be mounted next to the board and connected to the transceiver e.g. by a coaxial cable.
The inventors further propose that the antenna is mounted on board having a feed trace structure on the side opposite to the side of the antenna. This arrangement avoids close proximity between the feed structure and the cover member through which the antenna protrudes.
In a preferred embodiment of the invention, said cover member has a radial width of 13.5 mm or less. Further, the antenna is preferably configured to be accommodated within space of less than 7 mm between cover member and rollers.
The inventors further propose that no LC matching circuit is provided for matching the frequency bandwidth of the antenna. The LC matching cirquit would impair the overall Q factor of the network and it has turned out that the typical steel and grease environment is sufficient for matching the antenna.
A further aspect of the invention relates to a bearing including a bearing monitoring device as described above.
In a preferred embodiment of the invention, the bearing is a spherical roller bearing. The varying environment of the spherical roller bearing requires a particular degree of insensitivity against changes of the environment, which is what the invention provides.
In its preferred embodiment, the invention combines fractal antenna technology with bearings. The preferred fractal antenna is ultra wide band optimized for a rated frequency range between 3 - 6 GHz, which allows for the big detuning caused by the presence of grease/oil. The antenna is designed to fit in a steel cover that is mounted to the side of the bearing. Due to the large bandwidth (frequency range) of the fractal antenna, the inventors suggest a well defined "de-tuning" by design, i.e. in one of the designs the direct environment of the antenna will be controlled by encapsulation / potting of the antenna. The detuning by the controlled direct environment will shift the frequency range of the antenna from the rated frequency range to a range overlapping with the predetermined frequency range required by the application.
The above embodiments of the invention as well as the appended claims and figures show multiple characterizing features of the invention in specific combinations. The skilled person will easily be able to consider further combinations or sub-combinations of these features in order to adapt the invention as defined in the claims to his specific needs.
Brief Description of the Figures
Fig. 1 illustrates a bearing equipped with a bearing monitoring device ac- cording to the invention; and
Fig. 2 illustrates a circuit board for use in a bearing monitoring device according to Fig. 1 .
Detailed Description of the Embodiments
Fig. 1 illustrates schematically a grease lubricated spherical roller bearing having an inner ring 10, an outer ring 12 and plural rolling elements 14 formed as rollers arranged in a cage 16 between the inner ring 10 and the outer ring 12.
The rollers 14 are protected by a cover member 18 formed as a metal capping ring.
The system is a sensor bearing equipped with a bearing monitoring device including a sensor assembly 20 configured be mounted on the inside of the cover member 18 of a bearing or in a recess/window of the cover member 18. The sensor assembly 20 includes a wireless RF transceiver (not shown) for transmitting and receiving data relating to the operation of the sensor assembly in a predetermined frequency range which is a frequency range of a receiver 21 located roughly 1 m away from the bearing, wherein the wireless transceiver includes at least one antenna 22. The sensor assembly 20 further includes one or multiple sensors formed e.g. as temperature sensor, vibration sensor, acoustic emission sensor or probe for measuring the chemical properties of lubricant (not shown). Further, the sensor assembly 20 may optionally include power harvesting means or a battery for operating the wireless transmitter (not shown). In a sensor assembly 20 according to the invention, the antenna 22 has a rated frequency range, wherein a lower limit frequency of the rated frequency range is higher than an upper limit frequency of the predetermined frequency range.
In the preferred embodiment of the invention, the predetermined frequency range is the ISM band between 2.4GHz and 2.5GHz and the antenna is formed as a fractal SMD antenna chip for Ultra Wideband (UWB) applications having a rated frequency range between 3.1 and 5 GHz. In other words, the lower limit frequency of the rated frequency range is roughly 20% higher than the upper limit frequency of the predetermined frequency range. The cover member 18 / metal ring has at least one window 24 for the antenna 22 and the antenna chip is embedded into the window 24 such that the axially outer surface of the capping is essentially flat, i.e. that the antenna 22 does not protrude over the axially outer surface. The antenna 22 is quadratic with edges of 10 mm length and the window 24 is quadratic with edges of 13 mm length. The clearance between the antenna and the edges of the window has a width amounting to 30% of the length of the edges of the antenna 22 and is filled with potting material 26. The potting material 26 is selected based on its RF properties, i.e. is a RF controlled material.
Fig. 2 illustrates a printed circuit board 30 with an antenna 22 mounted thereon. A clearance zone (not illustrated) without ground plate is located beneath the antenna 22. A feed trace structure 28 is illustrated in dashed lines and arranged on the side facing the rollers 14 opposite to the side of the antenna 22. The board 30 has a curved shape adapted to the curvature of the cover member. The board has a radial width of 13.5 mm and spans about 40degrees in a circumferential direction of the cover ring 18.
The antenna 22 is configured to be accommodated within an axial space of less than 7 mm between cover member 18 and rollers. 14 The height of the assembly in Fig. 2 perpendicular to the drawing plane is therefore 7 mm or less.
In the final assembly, the board 30 (equipped with further electronic devices and/or sensors as desired) is fixed to the cover member 18 by a nylon screw and potted in order to protect the devices mounted on it.
The invention combines ultra high bandwith leading to insensitivety for the presence of grease/oil and metal and different geometries from bearing types/sizes with an impoved sensor cap design for achieving a controlled de- tuning by shaping the environment, and protection of a sensitive element from mechanical impacts.
The invention provides a wireless antenna 22 that can be integrated into a bearing end-cap or seal. This antenna design enables wireless data transmission in harsh environments that are common to bearing applications. The inventors have tested the device according to the invention for a bearing with 100 mm inner ring diameter and found a sufficient matching for a large variety of operating conditions including grease volumes at different locations for the 2.4 GHz frequency band.

Claims

Claims
1. Bearing monitoring device including:
a. a cover member (18) of a bearing;
b. a sensor assembly (20) mounted on said cover member (18); c. a wireless RF transceiver for transmitting and receiving data relating to the operation of the sensor assembly (20) in a predetermined frequency range, wherein the wireless RF transceiver includes at least one antenna (22);
characterized in that
said antenna (22) has a rated frequency range, said rated frequency range being defined as the frequency range within which the voltage standing wave ratio (VSWR) of the antenna determined in a neutral environment prior to mounting the antenna to the bearing monitoring device is 1 .1 or less, wherein a lower limit frequency of the rated frequency range is higher than an upper limit frequency of the predetermined frequency range, the predetermined frequency range being one of the ISM bands defined by the ITU-R in 5.138, 5.150, and 5.280.
2. Bearing monitoring device according to claim 1 ,
characterized in that
the lower limit frequency of the rated frequency range is at least 10% higher than the upper limit frequency of the predetermined frequency range.
3. Bearing monitoring device according to claim 1 and 2,
characterized in that
the lower limit frequency of the rated frequency range is at least 20% higher than the upper limit frequency of the predetermined frequency range.
4. Bearing monitoring device according to one of the preceding claims, characterized in that said rated frequency range of the antenna (22) is wider than the predetermined frequency range.
5. Bearing monitoring device according to one of the preceding claims, characterized in that
said predetermined frequency range is within the range below 2,5GHz and said lower limit of the rated frequency range is above 3 GHz.
6. Bearing monitoring device according to one of the preceding claims, characterized in that
said antenna has a rated frequency range between 3.1 and 5 GHz.
7. Bearing monitoring device according to one of the preceding claims, characterized in that
said antenna has a rated frequency range with a bandwidth of at least
1 .9 GHz.
8. Bearing monitoring device according to one of the preceding claims, characterized in that
said antenna is a chip antenna for Ultra Wideband (UWB) applications.
9. Bearing monitoring device according to one of the preceding claims, characterized in that
said cover is a metal ring (18) having at least one window (22) for the an- tenna (22).
10. Bearing monitoring device according to one of the preceding claims, characterized in that
said antenna (22) is mounted on board (30) with a clearance zone be- neath the antenna (22).
11. Bearing monitoring device according to one of the preceding claims, characterized in that
said antenna (22) is mounted on board (30) having a feed trace struc- ture (28) on the side opposite to the side of the antenna (22).
12. Bearing monitoring device according to one of the preceding claims, characterized in that
the antenna (22) is configured to be accommodated within space of less than 7 mm between the cover member (18) and the rollers (14).
13. Bearing monitoring device according to one of the preceding claims, characterized in that
no LC matching circuit is provided for matching the frequency bandwidth of the antenna (22).
14. Bearing including a bearing monitoring device according to one of the preceding claims.
15. Bearing according to claim 14,
characterized in that
the bearing is spherical roller bearing.
PCT/EP2015/078294 2015-01-26 2015-12-02 Wireless bearing monitoring device WO2016119949A1 (en)

Applications Claiming Priority (2)

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GB1501242.0 2015-01-26
GB1501242.0A GB2534419A (en) 2015-01-26 2015-01-26 Wireless bearing monitoring device

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AT524189A1 (en) * 2020-08-31 2022-03-15 Miba Gleitlager Austria Gmbh bearing element

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WO2021106418A1 (en) * 2019-11-28 2021-06-03 日立Astemo株式会社 Millimeter radio wave sensor and vehicle provided with same
JP2021085775A (en) * 2019-11-28 2021-06-03 日立Astemo株式会社 Millimeter wave radio sensor and vehicle including the same
JP7370829B2 (en) 2019-11-28 2023-10-30 日立Astemo株式会社 Millimeter wave radio sensor and vehicle equipped with it
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AT524189B1 (en) * 2020-08-31 2022-06-15 Miba Gleitlager Austria Gmbh bearing element

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