WO2014108169A1 - End cap for a bearing assembly - Google Patents

End cap for a bearing assembly Download PDF

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Publication number
WO2014108169A1
WO2014108169A1 PCT/EP2013/050198 EP2013050198W WO2014108169A1 WO 2014108169 A1 WO2014108169 A1 WO 2014108169A1 EP 2013050198 W EP2013050198 W EP 2013050198W WO 2014108169 A1 WO2014108169 A1 WO 2014108169A1
Authority
WO
WIPO (PCT)
Prior art keywords
end cap
pendulum unit
support member
bearing assembly
pendulum
Prior art date
Application number
PCT/EP2013/050198
Other languages
French (fr)
Inventor
Andreas Clemens Van Der Ham
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
Priority to PCT/EP2013/050198 priority Critical patent/WO2014108169A1/en
Publication of WO2014108169A1 publication Critical patent/WO2014108169A1/en

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Classifications

    • 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
    • F16C33/723—Shaft end sealing means, e.g. cup-shaped caps or covers
    • 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
    • F16C41/004—Electro-dynamic machines, e.g. motors, generators, actuators
    • 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
    • F16C19/383—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 with tapered rollers, i.e. rollers having essentially the shape of a truncated cone
    • F16C19/385—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 with tapered rollers, i.e. rollers having essentially the shape of a truncated cone with two rows, i.e. double-row tapered roller bearings
    • F16C19/386—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 with tapered rollers, i.e. rollers having essentially the shape of a truncated cone with two rows, i.e. double-row tapered roller bearings in O-arrangement
    • 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
    • F16C2326/00—Articles relating to transporting
    • F16C2326/10—Railway vehicles

Definitions

  • the present invention pertains to an end cap for a bearing assembly, which comprises a pendulum unit for energy harvesting. Additionally, the present invention pertains to a bearing assembly including an end cap which comprises a pendulum unit.
  • Condition monitoring units for bearing assemblies can be provided in many forms and located in various positions within the bearing assembly.
  • a condition monitoring unit can be arranged in the end cap of the bearing assembly.
  • end caps typically provide support for preventing accidents. End caps come in various shapes and sizes, and normally are made from either polypropylene (PP) or sheet steel. End caps should also have good resistance to chemicals. The end cap can be snapped easily into a recess of a housing bore of a bearing assembly or be mounted with an interference fit in the housing bore.
  • PP polypropylene
  • End caps are often used in freight rail cars.
  • the end cap has the function to preload the bearing inner ring and to protect the bearing against debris.
  • the end cap may include various electronic units, such as a monitoring unit. Since the electronic unit requires a connection to a power source, the end cap typically is connected to a battery or a power source.
  • the power source can either be located in a stationary part of the bearing assembly, or in the end cap itself. However, if the power source is arranged in the end cap, there is less space available for other components.
  • a general object of the present invention is to provide an improved end cap for a bearing assembly which is capable of generating energy under the influence of gravity by an oscillation of a pendulum unit.
  • an end cap for a bearing assembly.
  • the end cap comprises a support member for engaging a rotatable part of a bearing assembly.
  • the support member is configured to be rotatable around a centre axis A and comprises a pendulum unit suspended from the centre axis A as seen in a vertical plane X-Y of the end cap.
  • the pendulum unit is arranged to be guided along a trajectory on the support member.
  • the pendulum unit is adapted to oscillate between a first position and a second position along the trajectory under influence of gravity such that energy can be generated by an oscillation of the pendulum unit.
  • the present invention is based on the realization by the inventors that the function of a conventional pendulum is implemented into an end cap for a bearing assembly.
  • a classical pendulum is configured to convert energy, and more specifically, mechanical energy.
  • a pendulum typically consists of a mass, sometimes also denoted a bob, which is suspended to a pivot point, i.e. the centre axis A.
  • the support member is configured to be rotatable around the centre axis A, the pendulum unit is provided with a freedom of operation in a rotational direction ⁇ .
  • the freedom of operation of the pendulum unit is further defined by the fact that the pendulum unit is suspended from the centre axis A, as seen in the vertical plane X-Y of the end cap, and that the pendulum unit is arranged to be guided in a trajectory on the support member. That is, the pendulum unit is adapted to oscillate between the first position and the second position along the trajectory upon rotation of the end cap, i.e. the support member, and under the influence of gravity. As the pendulum unit moves due to rotation of the end cap around the centre axis A, it sweeps out a circular arc along the trajectory, oscillating in a periodic manner under the influence of gravity.
  • the pendulum unit Since the pendulum unit is suspended from the centre axis A, the pendulum unit is subjected to the gravity force as well as a force originating from the rotation of the end cap. Mechanical energy is then generated in the system, i.e. the pendulum unit, since the pendulum unit displaces from one position to another position upon rotation of the end cap.
  • the pendulum unit in an end cap and the provision that the pendulum unit is adapted to oscillate between a first position and a second position along the trajectory under the influence of gravity, it becomes possible to generate energy while the end cap rotates around its centre axis, e.g. when a railway bearing axis associated with the centre axis rotates.
  • the mechanical energy is generated by oscillation of the pendulum unit, and specifically due to a movement of the pendulum unit from the first position to the second position along the trajectory under the influence of gravity.
  • the energy generated from the pendulum unit may be converted into electrical energy which can be used to charge various electronic components, e.g. a battery, and/or power an electronic unit.
  • the present invention is particularly advantageous if the end cap includes a battery, since replacing the battery is very difficult once the bearing assembly has been mounted in, for example, a train wheel. In some cases, a battery is not even needed in the end cap since the electrical energy can be used to replace the battery.
  • the present invention provides an end cap which makes use of a motion associated with the pendulum unit as a supplemental energy source, and optionally transform the mechanical energy into electrical energy which can be utilized for various electrical components. That is, the pendulum unit is configured as an out of centre rotating mass, as seen from the centre axis A, which upon rotation of the support member is capable to generate mechanical energy under the influence of gravity by its suspension to the centre axis A such that the pendulum unit can displace from the first position to the second position.
  • the function of the end cap is to protect a shaft end of a bearing assembly in order to reduce hazards around many types of equipment.
  • the end cap is configured to snap into a recess of a housing bore of a bearing assembly.
  • the end cap may be configured to engage with an interference fit in a housing bore of a bearing assembly.
  • the end cap may be used in a freight rail application.
  • the end cap may also be used in a truck or car wheel hub or some other hub tied to a shaft to cover the bearing. Accordingly, the end cap is particularly suitable for a bearing assembly in a freight rail application
  • the present invention provides an end cap which is more suitable for including integrated electronic units in its structure due to the fact that an energy source in the form of the pendulum unit, as explained above, can be arranged within the end cap.
  • the present invention provides an end cap which is adapted for including wireless electronics such as a wireless monitoring unit.
  • the reasons for not applying the pendulum unit in the centre of the axis are, among other things, that the centre of the end cap is not available for this use and that it is more difficult to place enough mass at the centre to generate enough power without the mass sticking out far beyond the bolt heads.
  • the first position and the second position are two end-points of the trajectory.
  • the first position and the second position may be located as two intermediate points along the trajectory.
  • the first position is an intermediate point along the trajectory, whilst the second position is an end-point of the trajectory.
  • Other arrangements are also conceivable as long as the pendulum unit is capable to oscillate between two positions along the trajectory.
  • the trajectory may be formed by a recess in the support member.
  • the trajectory is further defined by the shape of the support member.
  • the recess is defined by an extension in a direction X, an extension in a direction T and an extension in a direction Z.
  • the support member may comprise a generator for transforming energy.
  • the generator may be configured to extract energy generated by the oscillation of the pendulum unit and to transform the energy into electrical energy. In this manner, it becomes possible to convert the energy harvested by the pendulum into electrical energy.
  • the energy generated by the oscillation of the pendulum unit may be transformed into electrical energy by electromagnetic means.
  • the energy generated by the oscillation of the pendulum unit may be transformed into electrical energy by piezoelectric means.
  • the generator may be provided in the form of a brushless DC generator.
  • the generator may be provided in the form of a reluctance type generator.
  • Other generators and/or combinations of generators are also contemplated as long as mechanical energy can be transformed into electrical energy.
  • the generator may be capable of receiving a part of the pendulum unit at least when the pendulum unit is in its second position.
  • the pendulum unit may have a magnetic part which generates a varying magnetic field as the pendulum unit oscillates.
  • the varying magnetic field induces a voltage in a coil provided in the end cap.
  • the coil may be an integral part of the generator.
  • electricity is generated by the oscillation of the magnet past the coil by magnetic or electromagnetic induction.
  • the magnet may also be referred to as the rotor, whilst the coil may be referred to as the stator.
  • the support member may comprise an electronic unit.
  • the generator may be configured to power the electronic unit.
  • the electronic unit may be arranged to monitor a condition of a bearing assembly.
  • the support member may further comprise a battery for powering an electronic unit. The generator may be connected to re-charge the battery.
  • the battery and the electronic unit may be arranged in a track extending along the support member.
  • the track can be defined by a recess in the support member. In this manner, it becomes possible to integrate the battery and the electronic unit without influencing the performance of the end cap.
  • the oscillation of the pendulum unit may further be limited by a
  • the amplitude angle a is set to optimise the power output over the frequency range required.
  • the size of the amplitude angle a depends on the application. If the rotational frequency is very low, the arc, i.e. the amplitude angle a, is preferably as large as possible. For higher rotational frequencies, the size of the amplitude angle is not as critical, and thus the movement is limited by the acceleration due to gravity and the inertia of the mass of the pendulum unit. At high frequencies, as the moment is limited, the mass can be extended to generate more power.
  • the oscillation of the pendulum unit may be limited by an amplitude angle a which is less than 180 degrees.
  • the oscillation of the pendulum unit may be limited by an amplitude angle a less than 135 degrees. Still preferably, the oscillation of the pendulum unit may be limited by an amplitude angle a less than 90 degrees.
  • the amplitude angle a is defined as the angle between the first position of the pendulum unit and the second position of the pendulum unit. In other words, the amplitude angle defines the arc of the movement of the pendulum unit. Accordingly, the amplitude angle a is formed at an intersection of the plane of the pendulum unit and the centre of axis of the end cap.
  • the end cap may comprise a suspension means arranged such that a tension is applied on the pendulum unit in a direction perpendicular to the rotating direction ⁇ of the support member, whereby the oscillation of the pendulum unit is limited by the suspension means. In this manner, the trajectory of the pendulum unit is further limited.
  • the suspension means is configured to have a low stiffness in a rotational direction ⁇ of the support member (or end cap), and a high stiffness in the axial direction A and the radial direction R.
  • the suspension means may be configured to generate energy upon
  • the suspension means may be integrated in the pendulum unit.
  • the suspension means may be arranged on the support member. It is also conceivable that at least one suspension means is an integral part of the pendulum unit, while a second suspension means is attached to the support member.
  • the suspension means may be provided in the form of a leaf spring or a helical spring.
  • the suspension means may comprise a piezoelectric material.
  • the pendulum unit may comprise a plucking piezo actuation unit.
  • the suspension means may comprise a plucking piezo actuation unit. The plucking actuation allows the piezoelectric actuator to be operated in resonance.
  • the piezoelectric fibres would be on a stationary part, e.g. the support member, and the fingers would be on the pendulum unit. Alternatively, the fingers may be arranged on the suspension means.
  • the pendulum unit may be suspended to the support member by a rod which is rotatably connected to the centre axis A of the support member and extends from the centre axis A of the support member to the pendulum unit.
  • the rod may be rotatably connected to the centre axis A by a rolling movement attachment such that a distance R is maintained constant over an oscillation period of the pendulum unit.
  • oscillation period refers to the movement of the pendulum unit from the first position to the second position and the return movement from the second position to the first position.
  • the distance R is defined as the distance between the centre point of the pendulum unit and the centre point of the axis A. This is a kind of plane bearing, while also a normal rotational ball bearing could be used.
  • the pendulum unit may be configured to resonate at a
  • the suspension means are configured to provide a mass spring system.
  • the resonance frequency should be chosen so as to provide sufficient power over the entire frequency range of the application. As is apparent to the skilled person in the art, the resonance peaks at one frequency only. Typically, the resonance frequency will be in the range of the application rotational frequency range.
  • the end cap may include a monitoring unit for monitoring a condition.
  • the end cap may include a wireless monitoring unit for monitoring a condition.
  • a bearing assembly comprises an end cap according to any of the aspects above.
  • the bearing assembly may comprise an inner ring, an outer ring and a set of rolling elements disposed therebetween.
  • the end cap may be adapted to engage the rotating outer ring.
  • the end cap may be adapted to engage another rotatable part of the bearing assembly, e.g. the inner ring or a shaft.
  • the end cap may include a monitoring unit for monitoring a condition of the bearing assembly.
  • the end cap may include a wireless monitoring unit for monitoring a condition of the bearing assembly.
  • the bearing assembly may further comprise any suitable rolling element bearing as is known in the art.
  • the rolling element bearing is formed of a radial rolling element bearing, a spherical roller thrust bearing, a tapered roller bearing, a cylindrical roller thrust bearing, a thrust ball bearing, an angular contact ball bearing, or a combination of the two or more of these bearing types.
  • the bearing assembly may comprise a first and a second rolling element bearing arrangement, wherein the first and the second rolling element bearings may be formed of different bearing types with different rolling element and raceways designs, such as according to the characteristics of any one of exemplified bearing types described above.
  • the present invention is particularly suitable for railway bearings.
  • an end cap for a freight rail application there is provided an end cap for a freight rail application.
  • a freight rail application including an end cap according to any of the aspects above.
  • the end cap may also be used in a truck or car wheel hub or some other hub tied to a shaft to cover the bearing.
  • Figures la- lb illustrate schematic perspective views of an exemplary end cap for a bearing assembly.
  • Figure 2 illustrates a schematic side view of an exemplary end cap having a pendulum unit according to the present invention.
  • Figure 3 a illustrates a schematic side view of an exemplary end caps including a pendulum unit according to an embodiment of the present invention.
  • Figure 3b illustrates a schematic side view of an exemplary end caps including a pendulum unit according to another embodiment of the present invention.
  • Figure 4 schematically illustrates an exemplary application of the end cap according to various embodiments of the present invention, in the form of a bearing assembly having an end cap.
  • Figures la- lb schematically illustrate an exemplary end cap 100 for a bearing assembly.
  • the end cap 100 has a support member 110 for engaging a rotatable part a bearing assembly.
  • the support member 110 may optionally be provided with one or more through bolt holes 115.
  • a through bolt hole 115 can be arranged in the middle of the support member 110.
  • further through bolt holes may be arranged from a distance of the centre of the support member 110, as shown in fig. la.
  • the function of the through bolt hole 115 is to regrind the bearing assembly, whilst the bearing assembly is still together.
  • Fig. la and fig. lb show the same view of the outwardly faced side of the end cap 100.
  • the slanted outer rim of the end cap 100 may be provided with a wall or outer ring that can hold the condition monitoring electronics or electronic units.
  • the end cap 100 may be used to pretension an inner ring of a bearing assembly. There may be a gap between the inwardly directed face of the support member 110 and the shaft to which the end cap is bolted. By tensioning the bolts a preload is provided by the end cap that presses against the inner ring of the bearing assembly by the ring on the inward side at the approximate diameter of the circle formed by the intersection of the front face of the support member 110 and the slanted outer face of the end cap 100 as depicted in figure lb.
  • centre bolt and the surrounding bolt holes are numbered by the same reference number 115. However, for clarity, one may choose to number the centre bolt hole differently from the other three surrounding bolt holes as they are all though holes.
  • the centre hole may also be plugged using some other form e.g. a rubber plug, which would not necessitate threading in the centre hole.
  • the end cap here further comprises a battery 190 and an electronic unit 200.
  • the battery 190 and the electronic unit 200 may be placed in a compartment, or a track or a recess, along the outer rim of the support member 110. In this manner, an integration of the electronic unit 200 and the battery 190 is possible without negatively influencing the performance of the end cap.
  • the battery 190 and the electronic unit 200 are, however, only optional features of the end cap 100.
  • the support member 110 may form the end cap 100. In other embodiments, the support member 110 may be an integrated part of the end cap 100. Typically, the support member 110 constitutes the major frame for the end cap structure.
  • the function of the end cap 100 is to protect the shaft end of bearing assembly in order to reduce hazards around many types of equipment.
  • the end cap 100 may provide support for preventing accidents.
  • the material of the end cap is typically polypropylene (PP) or sheet steel, and should have good resistance to most chemicals.
  • the end cap 100 can be snapped easily into a recess of the housing bore of a bearing assembly or be mounted with an interference fit in the housing bore.
  • Figure 4 shows an exemplary arrangement of an end cap 100 mounted on a bearing assembly 300. End caps are often used in freight rail cars. In this case, the end cap has the function to preload the bearing inner ring and to protect the bearing against debris
  • the end cap 100 may be used in a freight rail application. However, the end cap may also be used in a truck or car wheel hub or some other hub tied to a shaft to cover the bearing.
  • the support member 110 may have a circular shape with a diameter of about 200-250 mm.
  • the support member 110 has an extension in the X-direction, an extension in the Y-direction, and a thickness in the Z-direction, as is evident from figure la- lb and figure 2.
  • the final shape of the end cap 100 should be adapted to the application of the end cap and/or the shape of the bearing assembly it is attached to.
  • the end cap 100 is formed of a single material layer. It is also contemplated that the end cap 100 can be made of several layers of the same material.
  • Figure 2 illustrates a schematic side view of an exemplary end cap having a pendulum unit according to the present invention. More specifically, figure 2 schematically illustrates a side view of the support member 110 which includes a pendulum unit 120 according to the present invention.
  • the pendulum unit 120 typically has a mass.
  • the pendulum unit 120 is arranged to move along a trajectory 170. Due to the circular shape of the end cap 100, the trajectory 170 here is arc- shaped, as shown in fig. 2.
  • the pendulum unit 120 is adapted to oscillate between a first position 130 and a second position 140. As such, the first position 130 and the second position 140 are two end-points of the trajectory 170.
  • the first position 130 and the second position 140 may be located as two intermediate points along the trajectory 170 as long as the pendulum unit 120 is capable to oscillate between two positions.
  • the support member 110 is arranged to be rotatable around a centre axis A. In this manner, the support member 110 is rotatable around the centre axis A in the rotational direction ⁇ , as illustrated in fig. 2.
  • the centre axis A is regarded as the normal to the vertical X-Y plane of the support member 110.
  • the centre axis A is also the axis of rotation of the pendulum unit 120.
  • the support member 110 may also comprise a generator 210.
  • the function of the generator 210 is to transform the mechanical energy of the oscillating pendulum unit 120 into electrical energy. As illustrated in fig. 2, the generator 210 here is be adapted to receive a part of the pendulum unit 120.
  • the pendulum unit 120 may have a magnetic part which generates a varying magnetic field as the pendulum unit 120 oscillates.
  • the varying magnetic field induces a voltage in a coil provided in the end cap.
  • the coil may be an integral part of the generator 210, as shown in fig. 2.
  • electricity is generated by the oscillation of the magnet past the coil by magnetic or electromagnetic induction.
  • the magnet may also be referred to as the rotor, whilst the coil may be referred to as the stator.
  • the pendulum unit 120 is suspended from the centre axis A as seen in a vertical plane X-Y of the end cap 100.
  • the suspension of the pendulum unit 120 can be obtained in different ways, as will be evident from the non-limiting
  • Figure 3a schematically illustrates a side view of an exemplary end cap including a pendulum unit according to an embodiment of the present invention.
  • the pendulum unit 120 here is arranged to move along a trajectory 170 which is provided in the form of a recess 220.
  • the recess 220 may have a circular form with an inner diameter of about 160-180 mm, a width W of about at least 24 mm and a depth in the thickness direction, i.e. Z-direction, of about at least 20 mm.
  • the distance between the middle of the recess 220 and the outer rim of the support member 110 may be about 14 mm, as seen in the radial direction of the support member 110.
  • the height of the pendulum unit 120 may be from about 2 mm to about 21 mm.
  • the width of the pendulum unit 120 may be from about 2 mm to about 15 mm.
  • the length of the pendulum unit 120 may be from 2 mm to about 30 mm.
  • the length of the pendulum unit 120 may be up to the circumference of an arc defined by the radius of the pendulum movement, e.g. 160 - 180 mm/2, and an angle of 360 degrees minus the length of the arc used by the electronics, e.g. 120 degrees, minus any connectors, e.g. a length of 20 mm, minus the length of the arc used by the end stops, e.g.
  • the above dimensions are only provided as examples, and should not be construed as limiting in any sense. In other words, the dimensions may be chosen according to the specified application of the pendulum unit.
  • the end cap 100 may further comprise suspension means 150, 150'.
  • the suspension means 150, 150' are typically configured to limit the movement of the pendulum unit 120 to an amplitude angle a.
  • the amplitude angle a is defined as the angle between the first position 130 and the second position 140 of the pendulum unit 120. Accordingly, the amplitude angle a is formed at an intersection of the plane of the pendulum unit 120 and the centre axis A of the support member 110, as illustrated in figure 3a.
  • the suspension means 150, 150' may be integrated in the pendulum unit 120. In addition, or alternatively, the suspension means 150, 150' may be arranged on the support member 110.
  • At least one suspension means 150, 150' is an integral part of the pendulum unit 120, while a second suspension means 150, 150' is attached to the support member 110.
  • the function of the suspension means 150, 150' is to limit the movement of the pendulum unit 120 by applying a force to the pendulum unit 120.
  • the suspension means 150, 150' may be arranged such that a tension is applied on the pendulum unit 120 in a direction perpendicular to the rotating direction ⁇ of the support member 110. Thereby, the oscillation of the pendulum unit 120 is limited by the suspension means 150, 150'.
  • the suspension means 150, 150' can be provided in many different ways.
  • the suspension means 150, 150' may be a spring, such as a leaf spring or a helical spring.
  • the spring preferably has a low stiffness in the rotational direction ⁇ and a high stiffness in the axial direction A and the radial direction.
  • the spring may have a low stiffness in a circular path.
  • the suspension means 150, 150' may be magnets of equal polarity which are provided on the pendulum unit 120 and on the support member 110 adjacent to either the first position 130 or the second position 140.
  • suspension means are also contemplated as long as a sufficient level of tension can be applied to the pendulum unit 120. Hence, it is noted that the final design of the suspension means should be adapted to the application of the pendulum unit 120.
  • Figure 3b illustrates a schematic side view of an exemplary end cap including a pendulum unit according to another embodiment of the present invention.
  • the pendulum unit 120 is suspended to the support member 110 by a rod 160.
  • the purpose of the rod 160 is to connect the pendulum unit 120 to the centre axis A, i.e. to form a mechanical linkage.
  • the distance R is defined as the distance between the centre point of the pendulum unit 120 and the centre axis A.
  • the rod 160 may be rotatably connected to a rolling movement attachment 230, which is positioned at the centre axis A.
  • the rolling movement attachment 230 may advantageously have an oval shape.
  • the rolling movement attachment 230 can be defined as an attachment to the centre axis A, i.e. the middle of the support member 110, using an oval alike shape on a circular axis.
  • Friction is a critical factor for a smooth operation of the pendulum unit 120 since a large centripetal acceleration, up to 100 G, can occur due to the rotational speed in the rotational direction ⁇ .
  • a rolling movement attachment 230 is therefore advantageous over a bushing which imposes high friction forces between the shaft and the bushing such that energy is lost.
  • a rolling movement attachment 230 provides a smooth and homogenous rotation of the end cap 100.
  • the end cap may further comprise a generator 210.
  • the end cap 100 may comprise an electronic unit 200 and a battery 190.
  • FIG. 4 schematically illustrates an exemplary application of the end cap according to various embodiments of the present invention, in the form of a bearing assembly having an end cap.
  • the bearing assembly 300 may comprise an end cap 100, an inner ring 310, an outer ring 320 and a set of rolling elements 330.
  • the end cap engages a rotating part of the bearing assembly, e.g. a shaft.
  • the end cap is adapted to engage to a rotating part of the bearing assembly.
  • the end cap may engage a rotating outer ring.
  • the bearing assembly may be included in a freight rail car application.
  • the pendulum unit 120 oscillates under the influence of gravity between the first position 130 and the second position 140 on a trajectory 170 in the X-Y plane of the end cap 100 with the centre axis A as the rotation axis.
  • the trajectory 170 follows a recess 220 in the support member 110.
  • the pendulum unit 120 maintains a distance R to the centre axis over the oscillation period of the pendulum unit 120.
  • the rod 160 is provided in the form of a curved rod. In this manner, the pendulum unit 120 is connected to the curved rod.
  • the cross-sectional shape of the rod 160 may either be a rectangle, a circle or any other suitable shape which is capable of providing a pendulum movement.
  • the pendulum unit 120 may be attached to the rod 160 via a guiding, for example via a sliding bearing or a rolling bearing. It is to be noted that the final shape of the rod should be adapted to the application of the end cap and/or the shape of the bearing assembly it is attached to. Hence, various shapes of the rod are conceivable by the skilled person in the art.
  • the pendulum unit 120 preferably is operatively connected to the generator 210 such that mechanical energy generated by the pendulum unit 120 can be converted into electrical energy.
  • the electrical energy may be used to charge the battery 190 and/or power the electronic unit 200.
  • the end cap 100 may comprise an electronic unit 200, as shown in fig. la.
  • the electronic unit 200 can be configured to monitor the condition of the bearing assembly 300.
  • the electronic unit may comprise a condition monitoring unit.
  • the end cap 100 may comprise battery 190, as shown in fig. la
  • the generator 210 may be a brushless DC generator. Alternatively, the generator 210 may be a reluctance type generator. Other generators and/or combinations of generators are also contemplated as long as mechanical energy can be transformed into electrical energy.
  • the electrical energy may be generated by electromagnetic means.
  • the pendulum unit 120 may have a magnetic part which generates a varying magnetic field as the pendulum unit 120 oscillates.
  • the varying magnetic field induces a voltage in a coil provided in the end cap 100.
  • the coil may be an integral part of the generator 210.
  • the electrical energy may be generated by piezoelectric means.
  • the suspension means 150, 150' may comprise a piezoelectric material or a piezoelectric fibre plucking actuation unit.
  • suspension means 150, 150' may then be configured to generate energy upon deformation of the suspension means 150, 150' by the pendulum unit 120.
  • the pendulum unit 120 is adapted to oscillate between the first position 130 and the second position 140 along the trajectory 170 under the influence of gravity.
  • the mechanical energy is generated by oscillation of the pendulum unit 120, and specifically due to a movement of the pendulum unit 120 from the first position 130 to the second position 140 along the trajectory 170 under the influence of gravity.
  • the energy generated from the pendulum unit 120 may be converted into electrical energy which can be used to charge various electronic components, e.g. a battery, and/or power an electronic unit.
  • the present invention provides an end cap 100 which is more suitable for including integrated electronic units 200 in its structure due to the fact that an energy source in the form of the pendulum unit 120, as explained above, can be arranged within the end cap 100. In this manner, it becomes not only possible to charge a battery 190 in the end cap 100 without any electrical connection to a remote power source, but also to completely remove the battery from end cap structure enabling more space for additional electronic units 200. Accordingly, the present invention provides an end cap 100 which is adapted for including wireless electronics such as a wireless monitoring unit.

Abstract

The present invention relates to an end cap for a bearing assembly (300). The end cap comprises a support member (110) for engaging a rotatable part of a bearing assembly. The support member (110) is configured to be rotatable around a centre axis A and comprises a pendulum unit (120) suspended from the centre axis A as seen in a vertical plane X-Y of the end cap, and arranged to be guided along a trajectory (170) on the support member (110). The pendulum unit (120) is adapted to oscillate between a first position (130) and a second position (140) along the trajectory (170) under the influence of gravity such that energy can be generated by an oscillation of the pendulum unit (120).

Description

END CAP FOR A BEARING ASSEMBLY
FIELD OF THE INVENTION
The present invention pertains to an end cap for a bearing assembly, which comprises a pendulum unit for energy harvesting. Additionally, the present invention pertains to a bearing assembly including an end cap which comprises a pendulum unit.
BACKGROUND OF THE INVENTION
Condition monitoring units for bearing assemblies can be provided in many forms and located in various positions within the bearing assembly. As an example, a condition monitoring unit can be arranged in the end cap of the bearing assembly.
Typically, the function of the end cap is to protect the shaft ends of bearing assemblies in order to reduce hazards around many types of equipment. In addition end caps provide support for preventing accidents. End caps come in various shapes and sizes, and normally are made from either polypropylene (PP) or sheet steel. End caps should also have good resistance to chemicals. The end cap can be snapped easily into a recess of a housing bore of a bearing assembly or be mounted with an interference fit in the housing bore.
End caps are often used in freight rail cars. In this case, the end cap has the function to preload the bearing inner ring and to protect the bearing against debris.
In order to monitor a condition of the bearing assembly, the end cap may include various electronic units, such as a monitoring unit. Since the electronic unit requires a connection to a power source, the end cap typically is connected to a battery or a power source. The power source can either be located in a stationary part of the bearing assembly, or in the end cap itself. However, if the power source is arranged in the end cap, there is less space available for other components.
Despite the activity in the field, there remains a need for an end cap for a bearing assembly which combines high functionality with a simple and inexpensive construction, while maintaining a possibility for an integration of various electronic units.
SUMMARY OF THE INVENTION
In view of the above-mentioned and other drawbacks of the prior art, a general object of the present invention is to provide an improved end cap for a bearing assembly which is capable of generating energy under the influence of gravity by an oscillation of a pendulum unit. These and other objects are met by the subject-matters provided in the independent claims. Preferred optional features are recited in the associated dependent claims.
According to a first aspect of the present invention, there is provided an end cap for a bearing assembly. The end cap comprises a support member for engaging a rotatable part of a bearing assembly. The support member is configured to be rotatable around a centre axis A and comprises a pendulum unit suspended from the centre axis A as seen in a vertical plane X-Y of the end cap. The pendulum unit is arranged to be guided along a trajectory on the support member. Moreover, the pendulum unit is adapted to oscillate between a first position and a second position along the trajectory under influence of gravity such that energy can be generated by an oscillation of the pendulum unit.
The present invention is based on the realization by the inventors that the function of a conventional pendulum is implemented into an end cap for a bearing assembly. A classical pendulum is configured to convert energy, and more specifically, mechanical energy. Hence, a pendulum typically consists of a mass, sometimes also denoted a bob, which is suspended to a pivot point, i.e. the centre axis A. As such, by the provision that the support member is configured to be rotatable around the centre axis A, the pendulum unit is provided with a freedom of operation in a rotational direction ω. The freedom of operation of the pendulum unit is further defined by the fact that the pendulum unit is suspended from the centre axis A, as seen in the vertical plane X-Y of the end cap, and that the pendulum unit is arranged to be guided in a trajectory on the support member. That is, the pendulum unit is adapted to oscillate between the first position and the second position along the trajectory upon rotation of the end cap, i.e. the support member, and under the influence of gravity. As the pendulum unit moves due to rotation of the end cap around the centre axis A, it sweeps out a circular arc along the trajectory, oscillating in a periodic manner under the influence of gravity. Since the pendulum unit is suspended from the centre axis A, the pendulum unit is subjected to the gravity force as well as a force originating from the rotation of the end cap. Mechanical energy is then generated in the system, i.e. the pendulum unit, since the pendulum unit displaces from one position to another position upon rotation of the end cap.
Hence, by the incorporation of the pendulum unit in an end cap and the provision that the pendulum unit is adapted to oscillate between a first position and a second position along the trajectory under the influence of gravity, it becomes possible to generate energy while the end cap rotates around its centre axis, e.g. when a railway bearing axis associated with the centre axis rotates. The mechanical energy is generated by oscillation of the pendulum unit, and specifically due to a movement of the pendulum unit from the first position to the second position along the trajectory under the influence of gravity. The energy generated from the pendulum unit may be converted into electrical energy which can be used to charge various electronic components, e.g. a battery, and/or power an electronic unit. In this manner, the battery may need to be replaced less frequently. Hence, the present invention is particularly advantageous if the end cap includes a battery, since replacing the battery is very difficult once the bearing assembly has been mounted in, for example, a train wheel. In some cases, a battery is not even needed in the end cap since the electrical energy can be used to replace the battery.
Accordingly, the present invention provides an end cap which makes use of a motion associated with the pendulum unit as a supplemental energy source, and optionally transform the mechanical energy into electrical energy which can be utilized for various electrical components. That is, the pendulum unit is configured as an out of centre rotating mass, as seen from the centre axis A, which upon rotation of the support member is capable to generate mechanical energy under the influence of gravity by its suspension to the centre axis A such that the pendulum unit can displace from the first position to the second position.
Accordingly, by the present invention, it becomes possible to harvest energy generated by the resulting displacement variation of the pendulum unit. The function of the end cap is to protect a shaft end of a bearing assembly in order to reduce hazards around many types of equipment. Preferably, the end cap is configured to snap into a recess of a housing bore of a bearing assembly. In addition, or alternatively, the end cap may be configured to engage with an interference fit in a housing bore of a bearing assembly. The end cap may be used in a freight rail application. However, the end cap may also be used in a truck or car wheel hub or some other hub tied to a shaft to cover the bearing. Accordingly, the end cap is particularly suitable for a bearing assembly in a freight rail application
Since it is an increasing demand for integration of various electronic units, such as sensors and monitoring units, into the end cap structure, it is typically required that there is space left for a power source in the end cap. This is particularly important for wireless monitoring units since no electrical connection to an external power source is possible. However, due to the space limitations within an end cap, it is often complicated to arrange various electrical units in the end cap structure, i.e. the support member, while maintaining the functions of the end cap and meet the need for a wireless connection. In view of this, the present invention provides an end cap which is more suitable for including integrated electronic units in its structure due to the fact that an energy source in the form of the pendulum unit, as explained above, can be arranged within the end cap. In this manner, it becomes not only possible to charge a battery in the end cap without any electrical connection to a remote power source, but also to completely remove the battery from end cap structure enabling more space for additional electronic units. Accordingly, the present invention provides an end cap which is adapted for including wireless electronics such as a wireless monitoring unit.
The reasons for not applying the pendulum unit in the centre of the axis are, among other things, that the centre of the end cap is not available for this use and that it is more difficult to place enough mass at the centre to generate enough power without the mass sticking out far beyond the bolt heads.
Preferably, the first position and the second position are two end-points of the trajectory. Alternatively, the first position and the second position may be located as two intermediate points along the trajectory. Alternatively, the first position is an intermediate point along the trajectory, whilst the second position is an end-point of the trajectory. Other arrangements are also conceivable as long as the pendulum unit is capable to oscillate between two positions along the trajectory.
Preferably, the trajectory may be formed by a recess in the support member. In this manner, the trajectory is further defined by the shape of the support member. The recess is defined by an extension in a direction X, an extension in a direction T and an extension in a direction Z.
In various exemplifying embodiments, the support member may comprise a generator for transforming energy. The generator may be configured to extract energy generated by the oscillation of the pendulum unit and to transform the energy into electrical energy. In this manner, it becomes possible to convert the energy harvested by the pendulum into electrical energy.
In one exemplifying embodiment, the energy generated by the oscillation of the pendulum unit may be transformed into electrical energy by electromagnetic means. In another exemplifying embodiment, the energy generated by the oscillation of the pendulum unit may be transformed into electrical energy by piezoelectric means.
The generator may be provided in the form of a brushless DC generator. Alternatively, the generator may be provided in the form of a reluctance type generator. Other generators and/or combinations of generators are also contemplated as long as mechanical energy can be transformed into electrical energy. The generator may be capable of receiving a part of the pendulum unit at least when the pendulum unit is in its second position. For example, the pendulum unit may have a magnetic part which generates a varying magnetic field as the pendulum unit oscillates. The varying magnetic field induces a voltage in a coil provided in the end cap. In this respect of the invention, the coil may be an integral part of the generator. In other words, electricity is generated by the oscillation of the magnet past the coil by magnetic or electromagnetic induction. The magnet may also be referred to as the rotor, whilst the coil may be referred to as the stator.
In various exemplifying embodiments, the support member may comprise an electronic unit. In this manner, the generator may be configured to power the electronic unit. The electronic unit may be arranged to monitor a condition of a bearing assembly. In various exemplifying embodiments, the support member may further comprise a battery for powering an electronic unit. The generator may be connected to re-charge the battery.
The battery and the electronic unit may be arranged in a track extending along the support member. As an example, the track can be defined by a recess in the support member. In this manner, it becomes possible to integrate the battery and the electronic unit without influencing the performance of the end cap.
The oscillation of the pendulum unit may further be limited by a
predetermined amplitude angle a. The amplitude angle a is set to optimise the power output over the frequency range required. The size of the amplitude angle a depends on the application. If the rotational frequency is very low, the arc, i.e. the amplitude angle a, is preferably as large as possible. For higher rotational frequencies, the size of the amplitude angle is not as critical, and thus the movement is limited by the acceleration due to gravity and the inertia of the mass of the pendulum unit. At high frequencies, as the moment is limited, the mass can be extended to generate more power. Preferably, the oscillation of the pendulum unit may be limited by an amplitude angle a which is less than 180 degrees. Still preferably, the oscillation of the pendulum unit may be limited by an amplitude angle a less than 135 degrees. Still preferably, the oscillation of the pendulum unit may be limited by an amplitude angle a less than 90 degrees. By limiting the amplitude angle a to less than 90 degrees, there is more space for the mass and the pendulum unit is more suitable for a higher rotational frequency. In practice there is also an advantage to the smaller angle being that the suspension of the pendulum unit is more complicated for large amplitude angles. In the context of the present invention, the amplitude angle a is defined as the angle between the first position of the pendulum unit and the second position of the pendulum unit. In other words, the amplitude angle defines the arc of the movement of the pendulum unit. Accordingly, the amplitude angle a is formed at an intersection of the plane of the pendulum unit and the centre of axis of the end cap.
There are several different possibilities for suspending the pendulum unit to the centre axis A of the support member.
In one exemplifying embodiment, the end cap may comprise a suspension means arranged such that a tension is applied on the pendulum unit in a direction perpendicular to the rotating direction ω of the support member, whereby the oscillation of the pendulum unit is limited by the suspension means. In this manner, the trajectory of the pendulum unit is further limited. Preferably, the suspension means is configured to have a low stiffness in a rotational direction ω of the support member (or end cap), and a high stiffness in the axial direction A and the radial direction R.
The suspension means may be configured to generate energy upon
deformation of the suspension means by the pendulum unit. Moreover, by this arrangement, it becomes possible to utilize the deformation of the suspension means such that additional mechanical energy can be transformed into electrical energy. Transformation into electrical energy can be carried out e.g. by piezoelectric means, as mentioned below. The suspension means may be integrated in the pendulum unit. In addition, or alternatively, the suspension means may be arranged on the support member. It is also conceivable that at least one suspension means is an integral part of the pendulum unit, while a second suspension means is attached to the support member. The suspension means may be provided in the form of a leaf spring or a helical spring. The suspension means may comprise a piezoelectric material. In addition, or alternatively, the pendulum unit may comprise a plucking piezo actuation unit. In addition, or alternatively, the suspension means may comprise a plucking piezo actuation unit. The plucking actuation allows the piezoelectric actuator to be operated in resonance. The piezoelectric fibres would be on a stationary part, e.g. the support member, and the fingers would be on the pendulum unit. Alternatively, the fingers may be arranged on the suspension means.
In addition, or alternatively, the pendulum unit may be suspended to the support member by a rod which is rotatably connected to the centre axis A of the support member and extends from the centre axis A of the support member to the pendulum unit. The rod may be rotatably connected to the centre axis A by a rolling movement attachment such that a distance R is maintained constant over an oscillation period of the pendulum unit. In this context, the term oscillation period refers to the movement of the pendulum unit from the first position to the second position and the return movement from the second position to the first position. The distance R is defined as the distance between the centre point of the pendulum unit and the centre point of the axis A. This is a kind of plane bearing, while also a normal rotational ball bearing could be used.
Preferably, the pendulum unit may be configured to resonate at a
predetermined frequency. In this manner, the suspension means are configured to provide a mass spring system. The resonance frequency should be chosen so as to provide sufficient power over the entire frequency range of the application. As is apparent to the skilled person in the art, the resonance peaks at one frequency only. Typically, the resonance frequency will be in the range of the application rotational frequency range.
Preferably, the end cap may include a monitoring unit for monitoring a condition. Preferably, the end cap may include a wireless monitoring unit for monitoring a condition.
According to a second aspect of the present invention, there is provided a bearing assembly comprises an end cap according to any of the aspects above. The bearing assembly may comprise an inner ring, an outer ring and a set of rolling elements disposed therebetween. The end cap may be adapted to engage the rotating outer ring. In addition, or alternatively, the end cap may be adapted to engage another rotatable part of the bearing assembly, e.g. the inner ring or a shaft.
Preferably, the end cap may include a monitoring unit for monitoring a condition of the bearing assembly. Preferably, the end cap may include a wireless monitoring unit for monitoring a condition of the bearing assembly.
The bearing assembly may further comprise any suitable rolling element bearing as is known in the art. Hence, according to various exemplifying embodiments, the rolling element bearing is formed of a radial rolling element bearing, a spherical roller thrust bearing, a tapered roller bearing, a cylindrical roller thrust bearing, a thrust ball bearing, an angular contact ball bearing, or a combination of the two or more of these bearing types. For example, the bearing assembly may comprise a first and a second rolling element bearing arrangement, wherein the first and the second rolling element bearings may be formed of different bearing types with different rolling element and raceways designs, such as according to the characteristics of any one of exemplified bearing types described above. The present invention is particularly suitable for railway bearings. Hence, according to another aspect of the present invention, there is provided an end cap for a freight rail application. As such, there is also provided a freight rail application including an end cap according to any of the aspects above. However, the end cap may also be used in a truck or car wheel hub or some other hub tied to a shaft to cover the bearing.
Further effects and features of this second aspect of the present invention are largely analogous to those described above in connection with the first aspect of the invention.
Additional features of, and advantages with, the present invention will become apparent when studying the appended claims and the following description. The skilled addressee realize that different features of the present invention may be combined to create embodiments other than those described in the following, without departing from the scope of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS
The various aspects of the invention, including its particular features and advantages, will be readily understood from the following detailed description and the accompanying drawings, in which:
Figures la- lb illustrate schematic perspective views of an exemplary end cap for a bearing assembly.
Figure 2 illustrates a schematic side view of an exemplary end cap having a pendulum unit according to the present invention.
Figure 3 a illustrates a schematic side view of an exemplary end caps including a pendulum unit according to an embodiment of the present invention.
Figure 3b illustrates a schematic side view of an exemplary end caps including a pendulum unit according to another embodiment of the present invention.
Figure 4 schematically illustrates an exemplary application of the end cap according to various embodiments of the present invention, in the form of a bearing assembly having an end cap.
DETAILED DESCRIPTION The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which currently preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided for thoroughness and completeness, and fully convey the scope of the invention to the skilled addressee. Like reference characters refer to like elements throughout.
Figures la- lb schematically illustrate an exemplary end cap 100 for a bearing assembly. The end cap 100 has a support member 110 for engaging a rotatable part a bearing assembly. The support member 110 may optionally be provided with one or more through bolt holes 115. As an example, a through bolt hole 115 can be arranged in the middle of the support member 110. In addition, or alternatively, further through bolt holes may be arranged from a distance of the centre of the support member 110, as shown in fig. la. The function of the through bolt hole 115 is to regrind the bearing assembly, whilst the bearing assembly is still together. Fig. la and fig. lb show the same view of the outwardly faced side of the end cap 100. In a modified version, the slanted outer rim of the end cap 100 may be provided with a wall or outer ring that can hold the condition monitoring electronics or electronic units. The end cap 100 may be used to pretension an inner ring of a bearing assembly. There may be a gap between the inwardly directed face of the support member 110 and the shaft to which the end cap is bolted. By tensioning the bolts a preload is provided by the end cap that presses against the inner ring of the bearing assembly by the ring on the inward side at the approximate diameter of the circle formed by the intersection of the front face of the support member 110 and the slanted outer face of the end cap 100 as depicted in figure lb.
In the figures la and lb the centre bolt and the surrounding bolt holes are numbered by the same reference number 115. However, for clarity, one may choose to number the centre bolt hole differently from the other three surrounding bolt holes as they are all though holes. The centre hole may also be plugged using some other form e.g. a rubber plug, which would not necessitate threading in the centre hole.
As illustrated in fig. la and lb, the end cap here further comprises a battery 190 and an electronic unit 200. The battery 190 and the electronic unit 200 may be placed in a compartment, or a track or a recess, along the outer rim of the support member 110. In this manner, an integration of the electronic unit 200 and the battery 190 is possible without negatively influencing the performance of the end cap. The battery 190 and the electronic unit 200 are, however, only optional features of the end cap 100. In various exemplifying embodiments, the support member 110 may form the end cap 100. In other embodiments, the support member 110 may be an integrated part of the end cap 100. Typically, the support member 110 constitutes the major frame for the end cap structure.
The function of the end cap 100 is to protect the shaft end of bearing assembly in order to reduce hazards around many types of equipment. In addition, the end cap 100 may provide support for preventing accidents. The material of the end cap is typically polypropylene (PP) or sheet steel, and should have good resistance to most chemicals. The end cap 100 can be snapped easily into a recess of the housing bore of a bearing assembly or be mounted with an interference fit in the housing bore. Figure 4 shows an exemplary arrangement of an end cap 100 mounted on a bearing assembly 300. End caps are often used in freight rail cars. In this case, the end cap has the function to preload the bearing inner ring and to protect the bearing against debris
Although not shown in the figures, the end cap 100 may be used in a freight rail application. However, the end cap may also be used in a truck or car wheel hub or some other hub tied to a shaft to cover the bearing.
Preferably, and as illustrated in fig. la and lb, the support member 110 may have a circular shape with a diameter of about 200-250 mm. As such, the support member 110 has an extension in the X-direction, an extension in the Y-direction, and a thickness in the Z-direction, as is evident from figure la- lb and figure 2. It is to be noted that the final shape of the end cap 100 should be adapted to the application of the end cap and/or the shape of the bearing assembly it is attached to. Preferably, the end cap 100 is formed of a single material layer. It is also contemplated that the end cap 100 can be made of several layers of the same material.
Figure 2 illustrates a schematic side view of an exemplary end cap having a pendulum unit according to the present invention. More specifically, figure 2 schematically illustrates a side view of the support member 110 which includes a pendulum unit 120 according to the present invention. The pendulum unit 120 typically has a mass. The pendulum unit 120 is arranged to move along a trajectory 170. Due to the circular shape of the end cap 100, the trajectory 170 here is arc- shaped, as shown in fig. 2. In addition, the pendulum unit 120 is adapted to oscillate between a first position 130 and a second position 140. As such, the first position 130 and the second position 140 are two end-points of the trajectory 170. However, the first position 130 and the second position 140 may be located as two intermediate points along the trajectory 170 as long as the pendulum unit 120 is capable to oscillate between two positions.
The support member 110 is arranged to be rotatable around a centre axis A. In this manner, the support member 110 is rotatable around the centre axis A in the rotational direction ω, as illustrated in fig. 2. The centre axis A is regarded as the normal to the vertical X-Y plane of the support member 110. The centre axis A is also the axis of rotation of the pendulum unit 120. In various exemplifying embodiments, the support member 110 may also comprise a generator 210. In the context of the present invention, the function of the generator 210 is to transform the mechanical energy of the oscillating pendulum unit 120 into electrical energy. As illustrated in fig. 2, the generator 210 here is be adapted to receive a part of the pendulum unit 120. In this manner, it becomes possible to transform the mechanical energy of the oscillating pendulum unit 120 into electrical energy. For example, the pendulum unit 120 may have a magnetic part which generates a varying magnetic field as the pendulum unit 120 oscillates. The varying magnetic field induces a voltage in a coil provided in the end cap. In this respect of the invention, the coil may be an integral part of the generator 210, as shown in fig. 2. In other words, electricity is generated by the oscillation of the magnet past the coil by magnetic or electromagnetic induction. The magnet may also be referred to as the rotor, whilst the coil may be referred to as the stator.
Moreover, the pendulum unit 120 is suspended from the centre axis A as seen in a vertical plane X-Y of the end cap 100. The suspension of the pendulum unit 120 can be obtained in different ways, as will be evident from the non-limiting
embodiments below.
Figure 3a schematically illustrates a side view of an exemplary end cap including a pendulum unit according to an embodiment of the present invention. The pendulum unit 120 here is arranged to move along a trajectory 170 which is provided in the form of a recess 220. As an example, the recess 220 may have a circular form with an inner diameter of about 160-180 mm, a width W of about at least 24 mm and a depth in the thickness direction, i.e. Z-direction, of about at least 20 mm. The distance between the middle of the recess 220 and the outer rim of the support member 110 may be about 14 mm, as seen in the radial direction of the support member 110. The height of the pendulum unit 120 may be from about 2 mm to about 21 mm. The width of the pendulum unit 120 may be from about 2 mm to about 15 mm. The length of the pendulum unit 120 may be from 2 mm to about 30 mm. As an example, the length of the pendulum unit 120 may be up to the circumference of an arc defined by the radius of the pendulum movement, e.g. 160 - 180 mm/2, and an angle of 360 degrees minus the length of the arc used by the electronics, e.g. 120 degrees, minus any connectors, e.g. a length of 20 mm, minus the length of the arc used by the end stops, e.g. 20 mm each, minus the length of the arc used by the possible suspension means, e.g. 20 mm each, minus the length of the arc used by the generator, e.g. 30 mm. However, the above dimensions are only provided as examples, and should not be construed as limiting in any sense. In other words, the dimensions may be chosen according to the specified application of the pendulum unit.
As illustrated in figure 3a, the end cap 100 may further comprise suspension means 150, 150'. The suspension means 150, 150' are typically configured to limit the movement of the pendulum unit 120 to an amplitude angle a. In the context of the present invention, the amplitude angle a is defined as the angle between the first position 130 and the second position 140 of the pendulum unit 120. Accordingly, the amplitude angle a is formed at an intersection of the plane of the pendulum unit 120 and the centre axis A of the support member 110, as illustrated in figure 3a. The suspension means 150, 150' may be integrated in the pendulum unit 120. In addition, or alternatively, the suspension means 150, 150' may be arranged on the support member 110. It is also conceivable that at least one suspension means 150, 150' is an integral part of the pendulum unit 120, while a second suspension means 150, 150' is attached to the support member 110. The function of the suspension means 150, 150', as mentioned above, is to limit the movement of the pendulum unit 120 by applying a force to the pendulum unit 120. Preferably, the suspension means 150, 150' may be arranged such that a tension is applied on the pendulum unit 120 in a direction perpendicular to the rotating direction ω of the support member 110. Thereby, the oscillation of the pendulum unit 120 is limited by the suspension means 150, 150'.
The suspension means 150, 150' can be provided in many different ways. For instance, the suspension means 150, 150' may be a spring, such as a leaf spring or a helical spring. The spring preferably has a low stiffness in the rotational direction ω and a high stiffness in the axial direction A and the radial direction. Alternatively, the spring may have a low stiffness in a circular path. In various embodiments, the suspension means 150, 150' may be magnets of equal polarity which are provided on the pendulum unit 120 and on the support member 110 adjacent to either the first position 130 or the second position 140.
Other suspension means are also contemplated as long as a sufficient level of tension can be applied to the pendulum unit 120. Hence, it is noted that the final design of the suspension means should be adapted to the application of the pendulum unit 120.
Figure 3b illustrates a schematic side view of an exemplary end cap including a pendulum unit according to another embodiment of the present invention. In this embodiment, the pendulum unit 120 is suspended to the support member 110 by a rod 160.
The purpose of the rod 160 is to connect the pendulum unit 120 to the centre axis A, i.e. to form a mechanical linkage. In the context of the present invention, the distance R is defined as the distance between the centre point of the pendulum unit 120 and the centre axis A. The rod 160 may be rotatably connected to a rolling movement attachment 230, which is positioned at the centre axis A. As may be gleaned from figure 3b, the rolling movement attachment 230 may advantageously have an oval shape. Hence, the rolling movement attachment 230 can be defined as an attachment to the centre axis A, i.e. the middle of the support member 110, using an oval alike shape on a circular axis. The principle behind the use of a rolling movement attachment 230 is to reduce friction. Friction is a critical factor for a smooth operation of the pendulum unit 120 since a large centripetal acceleration, up to 100 G, can occur due to the rotational speed in the rotational direction ω. A rolling movement attachment 230 is therefore advantageous over a bushing which imposes high friction forces between the shaft and the bushing such that energy is lost.
Another advantage is that a rolling movement attachment 230 provides a smooth and homogenous rotation of the end cap 100. Analogous to the previous embodiment, the end cap may further comprise a generator 210. Moreover, the end cap 100 may comprise an electronic unit 200 and a battery 190.
Figure 4 schematically illustrates an exemplary application of the end cap according to various embodiments of the present invention, in the form of a bearing assembly having an end cap. The bearing assembly 300 may comprise an end cap 100, an inner ring 310, an outer ring 320 and a set of rolling elements 330. In the illustrated embodiment, the end cap engages a rotating part of the bearing assembly, e.g. a shaft. Hence, the end cap is adapted to engage to a rotating part of the bearing assembly. In addition, or alternatively, the end cap may engage a rotating outer ring. The bearing assembly may be included in a freight rail car application.
When the bearing assembly 300 rotates about the horizontal centre axis A passing through the centre of the end cap 100, the pendulum unit 120 oscillates under the influence of gravity between the first position 130 and the second position 140 on a trajectory 170 in the X-Y plane of the end cap 100 with the centre axis A as the rotation axis. The trajectory 170 follows a recess 220 in the support member 110. The pendulum unit 120 maintains a distance R to the centre axis over the oscillation period of the pendulum unit 120. In another embodiment of the present invention (although not shown), the rod 160 is provided in the form of a curved rod. In this manner, the pendulum unit 120 is connected to the curved rod. In addition, or alternatively, the cross-sectional shape of the rod 160 may either be a rectangle, a circle or any other suitable shape which is capable of providing a pendulum movement. In addition, or alternatively, the pendulum unit 120 may be attached to the rod 160 via a guiding, for example via a sliding bearing or a rolling bearing. It is to be noted that the final shape of the rod should be adapted to the application of the end cap and/or the shape of the bearing assembly it is attached to. Hence, various shapes of the rod are conceivable by the skilled person in the art. As mentioned above, the pendulum unit 120 preferably is operatively connected to the generator 210 such that mechanical energy generated by the pendulum unit 120 can be converted into electrical energy. The electrical energy may be used to charge the battery 190 and/or power the electronic unit 200. Hence, in all embodiments of the present invention, and as mentioned above, the end cap 100 may comprise an electronic unit 200, as shown in fig. la. The electronic unit 200 can be configured to monitor the condition of the bearing assembly 300. Hence, the electronic unit may comprise a condition monitoring unit. In addition, in all embodiments of the present invention, and as mentioned above, the end cap 100 may comprise battery 190, as shown in fig. la
The generator 210 may be a brushless DC generator. Alternatively, the generator 210 may be a reluctance type generator. Other generators and/or combinations of generators are also contemplated as long as mechanical energy can be transformed into electrical energy.
As mentioned above, in all embodiments of the present invention, the electrical energy may be generated by electromagnetic means. For example, the pendulum unit 120 may have a magnetic part which generates a varying magnetic field as the pendulum unit 120 oscillates. The varying magnetic field induces a voltage in a coil provided in the end cap 100. In this respect of the invention, the coil may be an integral part of the generator 210.
In addition, or alternatively, the electrical energy may be generated by piezoelectric means. For example, the suspension means 150, 150' may comprise a piezoelectric material or a piezoelectric fibre plucking actuation unit.
In addition, or alternatively, the suspension means 150, 150' may then be configured to generate energy upon deformation of the suspension means 150, 150' by the pendulum unit 120.
In all of the embodiments of the present invention, it becomes possible to harvest energy generated by the resulting displacement variation of the pendulum unit 120, i.e. the oscillation of the pendulum unit 120 between the first position 130 and the second position 140. This is particularly realized by the provision that the pendulum unit 120 is adapted to oscillate between the first position 130 and the second position 140 along the trajectory 170 under the influence of gravity. Thereby, it becomes possible to generate energy while the end cap 100 rotates around its centre axis. The mechanical energy is generated by oscillation of the pendulum unit 120, and specifically due to a movement of the pendulum unit 120 from the first position 130 to the second position 140 along the trajectory 170 under the influence of gravity. The energy generated from the pendulum unit 120 may be converted into electrical energy which can be used to charge various electronic components, e.g. a battery, and/or power an electronic unit. Moreover, the present invention provides an end cap 100 which is more suitable for including integrated electronic units 200 in its structure due to the fact that an energy source in the form of the pendulum unit 120, as explained above, can be arranged within the end cap 100. In this manner, it becomes not only possible to charge a battery 190 in the end cap 100 without any electrical connection to a remote power source, but also to completely remove the battery from end cap structure enabling more space for additional electronic units 200. Accordingly, the present invention provides an end cap 100 which is adapted for including wireless electronics such as a wireless monitoring unit.
Additionally, variations to the disclosed embodiments can be understood and effected by the skilled person in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word
"comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measured cannot be used to advantage.
Reference numerals
100 end cap
110 support member
115 through bolt hole
120 pendulum unit
130 first position
140 second position
150, 150' suspension means
160 rod 170 trajectory
190 battery
200 electronic unit
210 generator
220 recess
230 rolling movement attachment 300 bearing assembly
310 inner ring
320 outer ring
330 set of rolling elements A centre axis
X-Y vertical plane
ω rotation direction
a amplitude angle

Claims

1. An end cap for a bearing assembly (300), the end cap comprising a support member (110) for engaging a rotatable part of a bearing assembly, the support member (110) is configured to be rotatable around a centre axis A, wherein the support member (110) comprising a pendulum unit (120) suspended from the centre axis A as seen in a vertical plane X-Y of the end cap, and arranged to be guided along a trajectory (170) on the support member (110), wherein the pendulum unit (120) is adapted to oscillate between a first position (130) and a second position (140) along the trajectory (170) under an influence of gravity such that energy can be generated by an oscillation of the pendulum unit (120).
2. The end cap of claim 2, wherein the support member (110) further comprising a generator (210) for transforming energy, the generator (210) is configured to extract energy generated by the oscillation of the pendulum unit (120) and transform the energy into electrical energy.
3. The end cap of claim 2, wherein the generator (210) is capable of receiving a part of the pendulum unit (120) at least when the pendulum unit (120) is in the second position (140).
4. The end cap of any one of the preceding claims, wherein the trajectory (170) is formed by a recess (220) in the support member (110).
5. The end cap of any one of the preceding claims, wherein the oscillation of the pendulum unit (120) is limited by a predetermined amplitude angle a, where the amplitude angle a is preferably less than 180 degrees, more preferably less than 135 degrees, and even more preferably less than 90 degrees.
6. The end cap of any one of the preceding claims, wherein the end cap further comprising a suspension means (150, 150') arranged such that a tension is applied on the pendulum unit (120) in a direction perpendicular to the rotating direction ω of the support member (110), whereby the oscillation of the pendulum unit (120) is limited by the suspension means (150, 150').
7. The end cap of claim 6, wherein the suspension means (150, 150') is configured to generate energy upon deformation of the suspension means (150, 150') by the pendulum unit (120).
8. The end cap of claim 6 or claim 7, wherein the suspension means (150, 150') is integrated in the pendulum unit (120).
9. The end cap of claim 6 to claim 8, wherein the suspension means (150, 150') is arranged on the support member (110).
10. The end cap of any one of the preceding claims, wherein the suspension means (150, 150') is provided in the form of a leaf spring or a helical spring.
11. The end cap of any one of the preceding claims, wherein the pendulum unit (120) is suspended to the support member (110) by a rod (160), the rod (160) is rotatably connected to the centre axis A of the support member (110), and extends from the centre axis A of the support member (110) to the pendulum unit (120).
12. The end cap of claim 11, wherein the rod (160) is rotatably connected to the centre axis A by a rolling movement attachment (230) such that a distance (R) is maintained constant over the oscillation period of the pendulum unit (120)
13. The end cap of any one of the preceding claims, wherein the pendulum unit (120) is configured to resonate at a predetermined frequency.
14. A bearing assembly (300) comprising an end cap according to any one of the preceding claims.
15. The bearing assembly (300) of claim 14, further comprising an inner ring (310), an outer ring (320) and a set of rolling elements (330) disposed therebetween, wherein the end cap is adapted to engage to a rotating part of the bearing assembly, e.g. a rotating outer ring (320).
PCT/EP2013/050198 2013-01-08 2013-01-08 End cap for a bearing assembly WO2014108169A1 (en)

Priority Applications (1)

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PCT/EP2013/050198 WO2014108169A1 (en) 2013-01-08 2013-01-08 End cap for a bearing assembly

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20160126807A1 (en) * 2014-10-29 2016-05-05 Aktiebolaget Skf Bearing device with energy harvesting means
CN110282062A (en) * 2019-07-30 2019-09-27 蚌埠学院 A kind of self-power generation type single wheel balance car based on vehicle tyre power

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB701930A (en) * 1951-04-26 1954-01-06 Smith & Sons Ltd S Improvements in gravity-responsive monitoring devices
US20070152511A1 (en) * 2005-12-28 2007-07-05 Usc Corporation Generating device
DE102006044562A1 (en) * 2006-09-21 2008-04-10 Siemens Ag Wheel electronics arrangement, has wheel with bearing system which is provided with movable mass, where bearing system is arranged on circular segment path that is provided on rim bearing surface of wheel
WO2011153563A2 (en) * 2010-06-07 2011-12-15 Karl Eichhorn Device for converting kinetic energy into electrical energy

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB701930A (en) * 1951-04-26 1954-01-06 Smith & Sons Ltd S Improvements in gravity-responsive monitoring devices
US20070152511A1 (en) * 2005-12-28 2007-07-05 Usc Corporation Generating device
DE102006044562A1 (en) * 2006-09-21 2008-04-10 Siemens Ag Wheel electronics arrangement, has wheel with bearing system which is provided with movable mass, where bearing system is arranged on circular segment path that is provided on rim bearing surface of wheel
WO2011153563A2 (en) * 2010-06-07 2011-12-15 Karl Eichhorn Device for converting kinetic energy into electrical energy

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20160126807A1 (en) * 2014-10-29 2016-05-05 Aktiebolaget Skf Bearing device with energy harvesting means
CN105570321A (en) * 2014-10-29 2016-05-11 斯凯孚公司 Bearing device with energy harvesting means
US10491076B2 (en) 2014-10-29 2019-11-26 Aktiebolaget Skf Bearing device with energy harvesting means
CN105570321B (en) * 2014-10-29 2020-06-05 斯凯孚公司 Bearing arrangement with energy harvesting device
CN110282062A (en) * 2019-07-30 2019-09-27 蚌埠学院 A kind of self-power generation type single wheel balance car based on vehicle tyre power

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