Slewing ring bearing and method of assembling a slewing ring bearing

Abstract

A slewing ring bearing (42) comprising • - an outer slewing ring (1), • - an inner slewing ring (2) configured for fitting within the outer slewing ring (1), • - an axial bearing (200) provided between mutually facing surfaces of the outer slewing ring (1) and the inner slewing ring (2), which surfaces face in an axial direction of the slewing ring bearing (42), and • - a radial bearing (300) formed between mutually facing lateral surfaces of the outer slewing ring (1) and the inner slewing ring (2), wherein the outer slewing ring (1) comprises a first wall part (l1) and a second wall part (1"), wherein the first wall part (l1) is ring-shaped, and comprises a surface which faces in the axial direction slewing ring bearing (42), wherein the second wall (1") part comprises a cylindrical portion extending in the axial direction of the slewing ring bearing (42), wherein the first wall part l1 and a second wall part 1" of the outer slewing ring 1 are formed as a single integrated unit formed in one piece, wherein an outmost diameter of the inner slewing ring (2) is larger than an inner diameter of the outer slewing ring (1), wherein the inner slewing ring (2) comprises • - a first inner slewing ring part (19), and • - a second inner slewing ring part (20), wherein the axial bearing (200) is provided between the first inner slewing ring part (19) and the first wall (l1) of the outer slewing ring (1) and wherein the radial bearing (300) is provided between the second inner slewing ring part (20) and the second wall (1") of the outer slewing ring (1).

Description

[0001] SLEWING RING BEARING AND METHOD OF ASSEMBLING A SLEWING RING BEARING

[0002] The present invention relates to slewing ring bearings. More particularly the invention relates to a slewing ring bearing of the type having an axial bearing and a radial bearing. More particularly the invention relates to a method of assembling a slewing ring bearing of the type having an axial bearing and a radial bearing

[0003] Background of the invention

[0004] Slewing ring bearings, also known as slewing bearings, as such are known from many applications. In general, slewing ring bearings are used for rotation when a device, machine, vehicle or installation has two adjacent structures, which must rotate relative to each other. Slewing ring bearings usually supports heavy load, often on a horizontal plane. However, many are designed to receive high axial, radial and tilting moment load, regardless of the plane of rotation. Equally slewing ring bearings are expected to accommodate for thrust forces in all directions while maintaining the ability to rotate.

[0005] Slewing ring bearings comprise one inner and one outer ring, typically arranged with one or more rows of bearing elements (for example rolling elements, such as balls, cylindrical rollers, conical rollers, etc.) arranged between them to decrease friction between the inner and outer ring.

[0006] The French patent application FR372314 discloses a solid outer bearing ring. This disclosure reveals a radial ball bearing with additional axial ball bearing support, intended for rotational shafts. In order to assemble the bearing, the bearing races are very small and thereby weak. Further, it is almost impossible to add a cage to the radial bearing. If FR372314 is required to handle opposite axial thrust, a second outer ring must be added using fasteners, similar to how slewing ring bearings are manufactured today. Further FR372314 is an ordinary bearing, and not a slewing ring bearing. DE845927 discloses a slewing ring comprising a solid outer slewing ring. A single row of an axial angular contact bearing is required to handle both axial and radial thrust. Any axial moment thrust is supposed to be received by a waved spring ring, with the primary purpose of keeping the product together and no to facilitate rotation. It is uncertain how the spring element will be installed.

[0007] US 2007 0009191 discloses another bearing assembly. Even if the bearing comprises a solid outer bearing body, this bearing assembly does not accommodate for opposite axial thrust, but only axial and radial thrust. This while illustrating an invention, which does not seem to be able to be assembled, unless the outer metal sleeve is bent inwards as a finishing step of assembly.

[0008] Axial bearings are thrust bearings, which have applied load in an axial direction. Most axial bearings comprise numerous parts, such as roller elements arranged in a bearing cage between two bearing races. The bearing is installed in a system like a machine. Before installation the components of the bearing are often loose, and the bearing may be taken apart, thus risking contamination and lost components.

[0009] It is an object of the invention to provide an improved slewing ring bearing, which is simpler to assemble and is therefore more cost efficient to manufacture.

[0010] It is an object of the invention to provide an improved slewing ring bearing, which is more durable than prior art slewing ring bearings.

[0011] It is an object of the invention to provide an improved slewing ring bearing, with increased ability to withstand radial forces on the slewing ring bearing is use.

[0012] It is a further object of the invention to provide a method of assembling a slewing ring bearing of the type comprising both an axial bearing and a radial bearing, which method makes it simpler to assemble and is therefore more cost efficient to manufacture. It is further an object of the invention to provide a method of assembling a slewing ring bearing of the type comprising both an axial bearing and a radial bearing, that allows the bearing ring to be assembled from fewer parts.

[0013] It is also an objective of the invention to provide a slewing ring bearing, which is kept together as a single piece, in a manner which supports the rotation of the bearing.

[0014] It is also an objective of the invention to provide a slewing ring bearing which is capable of receiving considerable axial moment thrust, while supporting the rotation of the bearing.

[0015] It is further an object of the invention to provide a method of assembling a slewing ring bearing of the type comprising both an axial bearing and a radial bearing, where the method allows for inserting an increased number of bearing elements.

[0016] It is further an object of the invention to provide a method of assembling a slewing ring bearing of the type comprising both an axial bearing and a radial bearing, where the method allows for inserting larger bearing elements.

[0017] It is a further objective of the invention to provide an axial bearing which is kept together as a single piece, in a manner which supports the rotation of the slewing ring bearing, which is robust and capable of receiving radial thrust, and further being capable of receiving axial moment thrust.

[0018] It is further an object of the invention to increase the variety of options.

[0019] Summary of the invention

[0020] In a first aspect, the objects are achieved by a slewing ring bearing comprising

[0021] - an outer slewing ring,

[0022] - an inner slewing ring configured for fitting within the outer slewing ring, - an axial bearing provided between mutually facing surfaces of the outer slewing ring and the inner slewing ring, which surfaces face in an axial direction of the slewing ring bearing, and

[0023] - a radial bearing formed between mutually facing lateral surfaces of the outer slewing ring and the inner slewing ring, wherein the outer slewing ring comprises a first wall part and a second wall part, wherein the first wall part is ring-shaped, and comprises a surface which faces in the axial direction slewing ring bearing, wherein the second wall part comprises a cylindrical portion extending in the axial direction of the slewing ring bearing, wherein an outmost diameter of the inner slewing ring is larger than an inner diameter of the outer slewing ring, wherein the inner slewing ring comprises

[0024] - a first inner slewing ring part, and

[0025] - a second inner slewing ring part, wherein the axial bearing is provided between the first inner slewing ring part and the first wall of the outer slewing ring and wherein the radial bearing is provided between the second inner slewing ring part and the second wall of the outer slewing ring.

[0026] In an embodiment thereof the first inner slewing ring part and the second inner slewing ring part comprises cooperating connectors formed on the first inner slewing ring part and on the second inner slewing ring part, the cooperating connectors being configured for fixedly connecting the first inner slewing ring part, and the second inner slewing ring part fixed to each other.

[0027] In an alternative embodiment a surface of the first inner slewing ring part and a surface of the second inner slewing ring part facing each other may be provided with matching profiles, such that when the first inner slewing ring part and the second inner slewing ring part are abutting each other, they will be rotationally fixed to each other. In further embodiments, the first wall part and a second wall part of the outer slewing ring are formed as a single integrated unit formed in one piece.

[0028] In further embodiments, the axial bearing comprises axial bearing balls arranged between the mutually facing radially facing surfaces of first inner slewing ring part and the outer slewing ring.

[0029] In a further embodiment thereof, the axial bearing further comprises a groove axial bearing race formed on the first inner slewing ring part and a corresponding groove axial bearing race formed on the outer slewing ring.

[0030] In a further embodiment thereof, the axial bearing further comprises an axial angular contact bearing race formed on the first inner slewing ring part and a corresponding axial angular contact bearing race formed on the outer slewing ring.

[0031] In further embodiments, the axial bearing comprises axial bearing rollers arranged between the mutually facing axially facing surfaces of first inner slewing ring part and the outer slewing ring.

[0032] In a further embodiment thereof, the axial bearing further comprises an axial roller bearing race formed on the first inner slewing ring part and a corresponding axial roller bearing race formed on the outer slewing ring.

[0033] In further embodiments of any previous embodiment, the radial bearing comprises radial bearing balls arranged between the mutually facing radially facing surfaces of the second inner slewing ring part and the outer slewing ring.

[0034] In a further embodiment thereof, the radial bearing further comprises a groove radial bearing race formed on the second inner slewing ring part and a corresponding groove radial bearing race formed on the outer slewing ring.

[0035] In a further embodiment thereof, the radial bearing further comprises a radial angular contact bearing race formed on the second inner slewing ring part and a corresponding radial angular contact bearing race formed on the outer slewing ring. In further embodiments of any previous embodiment, the radial bearing comprises radial bearing rollers arranged between the mutually facing radially facing surfaces of the second inner slewing ring part and the outer slewing ring.

[0036] In a further embodiment thereof, the radial bearing further comprises a radial roller bearing race formed the second inner slewing ring part and a corresponding radial roller bearing race formed on the outer slewing ring.

[0037] In further embodiments of any previous embodiment, the inner slewing ring further comprises an intermediate inner slewing ring part, formed between the first inner slewing ring part and the second inner slewing ring part.

[0038] In a further embodiment thereof, the intermediate inner slewing ring part comprises a second radial bearing.

[0039] In a second aspect, the objects are achieved by method of assembling a slewing ring bearing, the slewing ring bearing comprising

[0040] - an outer slewing ring,

[0041] - an inner slewing ring configured for fitting within the outer slewing ring,

[0042] - an axial bearing provided between mutually facing surfaces of the outer slewing ring and the inner slewing ring, which surfaces face in an axial direction of the slewing ring bearing, and

[0043] - a radial bearing formed between mutually facing lateral surfaces of the outer slewing ring and the inner slewing ring, wherein the outer slewing ring comprises a first wall part and a second wall part, wherein the first wall part is ring-shaped, and comprises a surface which faces in the axial direction of the slewing ring bearing, wherein the second wall part comprises a cylindrical portion extending in the axial direction of the slewing ring bearing, wherein an outmost diameter of the inner slewing ring is larger than an inner diameter of the outer slewing ring, wherein the inner slewing ring comprises - a first inner slewing ring part, and

[0044] - a second inner slewing ring part, wherein the axial bearing is provided between the first inner slewing ring part and the first wall of the outer slewing ring and wherein the radial bearing is provided between the second inner slewing ring part and the second wall of the outer slewing ring, wherein the method comprises the steps of:

[0045] - arranging the first inner slewing ring part in the outer slewing ring, while providing an axial bearing there between,

[0046] - arranging a second inner slewing ring part in the outer slewing ring

[0047] - displacing the second inner slewing ring part in a radial direction relative to the outer slewing ring, thereby providing n temporary loading gap between the second inner slewing ring part and the outer slewing ring, which loading gap is dimensioned to receive a radial bearing ball,

[0048] - entering a plurality of radial bearing elements, through the loading gap into the radial bearing,

[0049] - sliding the second inner slewing ring part in a radial direction and relative to the outer slewing ring to a concentric position of the outer slewing ring and the inner slewing ring, and

[0050] - distributing the radial bearing elements, equidistantly in the radial bearing,

[0051] - inserting one or more radial bearing element, distributors for securing an even distribution of the plurality of bearing elements, in the radial bearing.

[0052] In an embodiment thereof, the method further comprises adding an axial bearing seal to the axial bearing and / or a adding radial bearing seal to the radial bearing.

[0053] In a further embodiment, the step of inserting one or more radial bearing ball distributers for securing an even distribution of the plurality of bearing elements, in the radial bearing comprises inserting a radial bearing cage.

[0054] In an embodiment thereof, the radial bearing cage is a crown bearing cage. In an embodiment of any previous embodiment of the second aspect, the inner slewing ring further comprises an intermediate inner slewing ring part, formed between the first inner slewing ring part and the second inner slewing ring part, and wherein the method comprises the step, before inserting the second inner slewing ring part into the outer slewing ring, inserting an intermediate inner slewing ring part into the outer slewing ring.

[0055] Any embodiment may be provided with holes or recesses for any purpose, such may be lubrication of bearing rows or to fit gears or sensors of any kind.

[0056] If it is required of an embodiment, it can be provided with suspension. Such suspension can be arranged as part of the inner or outer slewing ring and comprise of flexible material, spring arrangements, hydraulic suspension or pneumatic suspension or any other kind.

[0057] Bearings in general are forged or milled. The outer slewing ring of the present invention relies on a hollow shell shape, which would require further processing than just molding or single plane forging. A molded part could easily have additional milling added to create a deep radial bearing race, deep enough to handle axial moment. Undercut milling or undercut machining would be the preferred technique, preferable with specialized tools.

[0058] Inner slewing rings are easier to mold, also without post processing. Milling the inner slewing rings is also easy.

[0059] Both the inner and outer slewing ring may be manufactured from any suitable material. For slewing rings which need less strength, it would be cheap to manufacture in polymers. Some polymers would even contribute with benefits such as corrosion resistance, self-lubrication, cost-savings and constant friction coefficient throughout lifetime.

[0060] Carbon fiber or ceramic materials have high strength and are often chosen for bearing races in combination with steel balls. An alternative metal manufacturing could be high-pressure pressing and tooled rolling of sheet metal parts. Such manufacturing processes would be able to create strong metal at a low unit cost. Both inner and outer slewing ring could be manufactured in such a fashion.

[0061] The plasticity of a material may help to assemble an embodiment if tight fits are an issue, or to assist in preloading a slewing ring bearing.

[0062] Both the inner and outer slewing rings may each comprise deferent materials. An example of such composites could be thin bearing races made of a strong material and molded into a larger solid body of polymer or another suitable material. Further composite solutions could be bearing races covered with a foil or coating of any suitable types. For the avoidance of fasteners, the outer slewing ring must comprise of a single combined body at the time of assembly.

[0063] The absence of fasteners in the assembly process does not deny either slewing ring to have fasteners for mounting purposes.

[0064] Each of the outer and inner slewing ring can be part of a larger body, in this way it is easier to incorporate the present invention into a system. The outer slewing ring can simply be manufactured as part of a chassis, without the need of mounting the slewing ring to the chassis as an assembly step.

[0065] Any parts of the present invention may be manufactured by additive manufacturing. Hereby achieving assembly of elements which otherwise would not be able to be assembled. Such manufacturing processes may include materials as metals, metal alloys, ceramics, polymers, carbon composites and composite in general.

[0066] In general, the most common bearing types are: Plain bearings, ball bearings, roller bearings, flexure bearings, tilting pad bearings, fluid bearings and magnetic bearings.

[0067] The most cost-efficient bearings are rolling element bearings or plain bearings. Rolling elements are most commonly made from hardened steel alloys, where spherical balls or rollers are fixed with equal distance in cages and rolling within bearing raceways.

[0068] The most common rolling element bearing is the ball bearing, which most often is arranged as: Deep groove ball bearing or angular contact ball bearing.

[0069] Bearing rollers vary in shape to fit different needs. Needle rollers are cheap cylindrical rollers, which are good at evening distribution of thrust. Tapered rollers are conical in shape to even the rotational speed of the roller surface in relation to the bearing raceway. Spherical rollers or barrel rollers are shaped to fit the assembly process and even the distribution of thrust when in use.

[0070] Plain bearings or sliding contact bearings are bearings, where low-friction motion is achieved by plain surfaces sliding against each other due to properties of selflubricating materials, general lubrication or due to difference in material properties thus achieving sliding abilities when exposed to thrust.

[0071] An embodiment may be provided with either fluid bearings, magnetic bearings or tilting pad bearings, however these bearing types are intended for extremely high speeds, and a swirling bearing for caster wheels rarely spins fast. The wheel itself may have high speed, but the change in direction is limited.

[0072] The strongest type of bearing, as the applied weight load is direct vertical thrust load, would be an axial bearing.

[0073] The bearing is exposed to some amount of radial thrust, however axial moment forces are far greater than the radial forces. This supports the requirement for the second outer bearing race to be provided with a bearing raceway, thus ensuring low-friction rotation in scenarios of directional change or sudden change in thrust of load, such as in active driving situations.

[0074] An axial bearing may be of any suitable type, preferably of rolling elements or sliding contact. A ball bearing may be a deep groove ball bearing or an angular contact axial bearing, both types capable of receiving radial forces. Other preferable axial bearing types may be roller bearings, such as tapered rollers or barrel rollers.

[0075] Needle rollers are cheap, however the forces applied to a multidirectional caster wheel may be dynamic and consist of a variety of axial and radial forces. Needle rollers might need additional radial support. Such needs may be solved by additional bearing raceways.

[0076] A sliding contact bearing or plain bearing may be adapted with a curvature to receive radial forces.

[0077] The bearing type of the first and the second outer race may be of the same or of a different type, like an embodiment comprising a first outer race provided with a ball bearing raceway and a second outer race provided with a sliding contact bearing raceway.

[0078] The bearing race or raceways of the first and second outer race may be a bearing common to both races, such as if each race comprises one fourth of a four point contact bearing.

[0079] An angular axial raceway of the second outer bearing race may be correlating an angular axial bearing raceway of the first outer bearing race, thus completing a combined radial bearing raceway. Such an assembly will allow a rolling element radial bearing to be loaded with maximum capacity of rolling elements.

[0080] In a preferred embodiment the raceway of the first outer race faces the drive surface, thus the second outer race is installed form the direction intended to face the drive surface.

[0081] The inner bearing race comprises bearing raceways equal to and correlating any bearing raceway of the outer bearing races. Thus, any thrust applied to the outer races will be transferred to the inner race. The inner race may be provided with additional inner races if needed.

[0082] Bearing cages are crucial parts of bearings. Cages keep rolling elements fixed with equal spacing and cages ensure that a bearing will stay in its working arrangement and not fall apart.

[0083] Cages may be made from various materials like metal alloys and polymers. The shapes, sizes and rolling element capacity is often determined by the assembly process of the bearing.

[0084] In a preferred embodiment, the bearing comprises at least one cage adapted to separate the rolling elements.

[0085] Alternatives to cages may be individual spacers. Such spacers are common to four point contact bearings.

[0086] To protect a bearing from its environment, bearing seals are used to keep contamination out, and further to keep lubrication within.

[0087] Bearing seals are often made from flexible materials and often in combination with hollow discs of a harder material. Variations of cages are made with in-build seals as a combined part.

[0088] Bearing shields are often made from metal and are designed to withstand impacts and protect the bearing mechanisms. Shields are arranged between the races and cover the gaps, where a cage or seal is not efficient.

[0089] In highly contaminated environments labyrinth seals are often used to protect axial bearings. Labyrinth seals are non-contact mechanical shields which though a narrow corridor with shifting path of correlating tongue and groove arranged on each bearing race, makes it difficult for dust, dirt and debris to enter an axial bearing. Labyrinths are often combined with seals of flexible materials. Different bearing races may be made from different materials. One race may be made from a material chosen for its high hardness and wear resistance, while another would be chosen for its excellent low-frictional properties to reduce energy loss during rotation.

[0090] Steel based alloys often used in bearing manufacturing are high carbon chromium bearing steel, carburizing steel and stainless steel.

[0091] Titanium alloys are used for bearings requiring high strength and high corrosion resistance.

[0092] Any bearing race may be made from ceramic materials like silicon nitride, alumina oxide, zirconia oxide or silicon carbide.

[0093] In a preferred embodiment, at least one bearing race is made from a self-lubricating material.

[0094] Other metal alloys used for bearings would among others be aluminum, copper, indium, tin, lead, silver, gold, brass, babbitt or sintered bronze and iron, which are suitable due to their self-lubricating properties.

[0095] Any inner or outer bearing race may comprise metal salts, such as sulfides, selenides, chlorides, iodides, oxides or hydroxides, which are suitable due to their self-lubricating properties.

[0096] Any bearing race may be made from or comprise of glasses such as boron oxide, silicates or phosphates, which are beneficial for the self-lubricating properties.

[0097] In a preferred embodiment any inner or outer race may be manufactured from polymers.

[0098] At least one bearing race may be made from plastic materials like polyether ether ketone (PEEK), which is used for bearings that need to be lightweight and resistant to corrosion. Any bearing race may be made from polytetrafluoroethylene (PTFE) or linear polyethylene (PE), which are suitable due to their self-lubricating properties.

[0099] A preferred embodiment of the invention may have any inner or outer races or raceways made from pressed sheet metal.

[0100] Yet another preferred embodiment may have races or raceways made from one or more materials molded into any suitable polymer or metal alloy. Hereby combining into a common composite race.

[0101] In a preferred embodiment, the bearing comprises a lubricant.

[0102] The bearing may be lubricated with petroleum-based oils, which are advantageous for their high lubricity and cooling capabilities.

[0103] The bearing may be lubricated with synthetic oils. These lubricants are advantageous for their high-temperature stability and long service life.

[0104] The bearing may be lubricated with greases, which are advantageous for their ability to stay in place and provide long-term lubrication.

[0105] The bearing may be lubricated with dry lubricants like graphite or boron nitride.

[0106] These lubricants are beneficial for reducing friction in harsh conditions where grease and oil will not work, such as radioactive or vacuum environments.

[0107] The bearing may be lubricated with solid film lubricants, which are advantageous in conditions with very high or very low temperatures.

[0108] The first outer race may be part of a larger body or arranged with any type of fasteners, brackets or similar arrangements.

[0109] Any bearing race may comprise of independent bearing raceways, thus allowing for raceways to be made from different materials than the races themselves. This is cost-effective if a race is made from injection molded polymer and the raceway is made from metal.

[0110] The wheel is adapted for rotation around a central axle. The axle is connected to the inner race by a wheel fork. The central axle itself may be adapted for rotation.

[0111] The wheel fork may be an integrated part of the inner race or connected to the inner race in any suitable way.

[0112] The wheel fork or the inner race may be the base of additional added functions, such as sensors.

[0113] Caster wheel tires are made from materials chosen for their properties to drive under certain conditions and in curtain environments. The majority of caster wheel tires are made from polymers; however steel or aluminum alloys are used when exceptional strength or temperature resistance are required.

[0114] In a preferred embodiment a caster wheel tire may be made from polyurethane- elastomer, which is beneficial due to low rolling friction and high toughness towards rifts and cuts.

[0115] In another preferred embodiment at least one caster wheel tire is made from solid rubbers like thermoplastic rubber elastomer or silicone-elastomer, which are advantageous for their strength and low rolling resistance.

[0116] In an embodiment of the invention at least one wheel tire may be arranged with pneumatic rubber tires, which are light weight and gentle to ground surfaces.

[0117] An embodiment intended for cleanroom environments may be made from thermoplastic polyurethane.

[0118] In a preferred embodiment at least one wheel tire is made from polypropylene or polyamide, which are beneficial due to their chemical resistance. Another advantage of polypropylene and polyamide is the option of manufacturing the wheel tire and rim as a single injection molded part.

[0119] Combined rims and tires intended for high heat environments may be made from fenolplastic, which is heat resistant but is in lag of driving performance on uneven surfaces.

[0120] Any wheel system may be arranged with a brake device, which will block one or more wheels when activated. Such breaks are common on caster wheels and advantageous when a vehicle is required to be fixed from running.

[0121] In a preferred embodiment a brake device may block at least one wheel tire.

[0122] In another preferred embodiment a brake device may block at least one wheel rim.

[0123] In yet another preferred embodiment at least one outer race or wheel rim is arranged with a brake disc.

[0124] An embodiment may be adapted with a brake which blocks the swirling bearing from changing the direction of the caster wheel.

[0125] An embodiment may be provided with a levering, which comprises a leg part, which may be activated to gain contact to the drive surface. Such levering may even lift the caster from the drive surface.

[0126] The caster wheel offset is the horizontal distance between the vertical rotational axis of the caster bearing and the horizontal rotational axis of the wheel. This allows for the caster to change direction together with the vehicle on which it is attached and run along in a new direction.

[0127] The offset influences the diameter of a swirling bearing of a low-profile caster wheel.

[0128] An offset which is too short will cause the caster to flutter and repeatedly swing from side to side. The flutter may be reduced by the use of multiple wheels, as the swinging will be stabilized, thus a shorter offset and hereby a smaller enclosing bearing may provide good driving abilities.

[0129] In the field of robotics and automated systems more advanced technologies are often required to control motion in various ways.

[0130] Encoders are devices used for monitoring speed and direction of rotation. Encoders comprise of a code ring and a sensor to read the code. Code rings are provided with a pattern or similar readable details, which the sensor can detect and transmit for the determination of the circular position and the rotational speed of the code ring. Encoders are classified as either mechanical, optical, magnetic or electromagnetic induction. Further, the output of the sensor is either absolute or incremental. An absolute signal is preferred to determine position, which is crucial in robotics.

[0131] Another embodiment may be arranged with vision-based monitoring of rotational position.

[0132] Directionally controlled applications like mobile robots, would benefit from an embodiment being arranged with a row of gear teeth concentric to the bearing raceways. Such gear transmission may be of any suitable type like a spur gear, helical gear, bevel gear, worm gear or magnetic gear. Hereby enabling directional control of the wheel. A gear may be powered by any type of motor. Electric servo or stepper motors a preferable.

[0133] A gear ring be mounted to the inner race or the inner race may be adapted with a gear as at part of the race.

[0134] In another preferred embodiment a gear may be operated by a gear belt.

[0135] An alternative powered transmission could be the use of a motor ring. A motor ring runs by the same physics as ordinary motors, except for the hollow core. Both AC and DC motors can be adapted to fit within a swirling bearing. AC / DC servo and DC stepper motors are the most precise and easiest to control with micro rotations and accuracy. Motor controllers are required for use of both servos and steppers. A servo motor comprises any type of motor in combination with an encoder to monitor position. Motor type may vary with demands to precision and torque.

[0136] In the field of robotics the invention is further advantageous for powered omnidirectional drive. In such embodiments the swirling bearing may be arranged with means for transfer of electric power and signal.

[0137] A preferred embodiment of a caster wheel system may have the swirling bearing arranged with at least one conductive ring for wireless transmission of power or signal. Such conductive rings and correlating conductive contacts is advantageous for powering drive wheels, various sensors, gear motors, brake systems and PCBs, such as microcontrollers or CPUs.

[0138] Another preferred embodiment of a caster wheel system may have the swirling bearing arranged with an induction ring for wireless transmission of power and signal. An induction system comprising two inductive transceivers is advantageous due to a two-way communication.

[0139] The primary type of wireless data transmission in electronics is radio frequency, which is the basis of technologies like blue tooth, Wi-Fi and cellular communications.

[0140] The three most suitable wireless power transfer technologies would be inductive coupling, resonant inductive coupling and capacitive coupling.

[0141] It is possible for a wireless power transfer system to also transfer data. A system of both power transfer and two-way data transfer is known as Wireless Powered Communication.

[0142] An embodiment could comprise of a main power transfer through slip rings, which has the lowest power loss, and a wireless connection for data transmission.

[0143] A preferred embodiment of a caster wheel system may comprise a microcontroller or PCB such as a CPU or motor driver. Any embodiment may comprise of a hollow central axle, which is advantageous due to the ability to have wires and cables passing though the wheel.

[0144] When power and control is transferred to the inner race, means of directional control may be operated from within the swirling bearing. Such arrangement may comprise of at least one smaller gear arranged for rotation as part of the inner race and being in correlation with a gear ring provided to an outer bearing race. Such smaller gear may be powered by any type for suitable motor, like a servo- or stepper-motor. The servomotor is particularly advantageous as it comprises an internal encoder.

[0145] The wheel may be powered by any type of motor. Such motor can be of any AC or DC type, however servos and steppers are the best to control. Hub motors, which are motors integrated in the wheel with either direct drive or planetary gears, are a reliable and compact choice, the stator is part of the inside of the wheel, and the rotor on the outside. Most motors for such a purpose would need a motor controller as part of the circuit. A gear may be provided between the wheel and a chosen motor. Multiple wheels can each be provided with motors.

[0146] Wheels with or without motor may benefit from having an encoder unit as part of the wheel to sense the rotational speed of the wheel. This is crucial to many robotic systems in relation to monitoring its own movement. Such encoders are normally part of the wheel hub mounted on the wheel and the axle.

[0147] A preferred embodiment of a caster wheel system may comprise one or more sensors.

[0148] For the purpose of monitoring position an Inertial Measurement Unit (IMU) which comprises a gyroscope, will measure velocity, orientation, gravitational forces, thus aiding in navigation and control. A position sensor will further aid in determine the precise position in an environment.

[0149] In navigational and orientational aspects a proximity sensor will detect obstacles in path of the wheels; an optical sensor may be used for line tracking and edge detection; an ultrasonic sensor may preform obstacle detection in path of wheels; a laser sensor such as a LiDAR may preform precise distance measurement and obstacle detection; and a magnetic sensor or Hall Effect sensor may detect magnetic fields useful for navigation and positioning.

[0150] A caster wheel system will benefit from a load sensor, which may measure load on wheels and aiding in balancing and optimizing movement.

[0151] To monitor an embodiment of a caster wheel itself a temperature sensor may detect overheating of a motor and other components; a vibration sensor may aid in detecting abnormal vibrations, which might be indicative of mechanical issues; a strain gauge may be measuring deformation or displacement of parts of the device, thus aiding to ensure structural integrity.

[0152] An embodiment of a caster wheel system may benefit from monitoring the environment by an acoustic sensor for change in ambient noise; a pressure sensor for changes in ambient air pressure; and temperature sensor for changes in ambient thermal conditions.

[0153] It is to be understood that a caster wheel system may comprise of any combination of sensors, depending on a specific use of the caster.

[0154] A preferred embodiment of a caster wheel system may comprise one or more batteries.

[0155] Yet another preferred embodiment of a caster wheel system may comprise one or more lights, which are advantageous for vision-based navigation and for hazard indication.

[0156] An embodiment of the invention may be arranged with any type of suspension.

[0157] Suspension systems often comprise of pneumatic or hydraulic pressurized systems, metal springs or elastic polymers. In a preferred embodiment a suspension system is provided between the wheel and the swirling bearing.

[0158] In another embodiment a suspension system is provided between the swirling bearing.

[0159] It is to be understood that additional added technology may be connected to an embodiment by any suitable technique.

[0160] It should be emphasized that the term "comprises / comprising / comprised of' when used in this specification is taken to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

[0161] Brief description of the drawings

[0162] In the following, the invention will be described in greater detail with reference to embodiments shown by the enclosed figures. It should be emphasized that the embodiments shown are used for example purposes only and should not be used to limit the scope of the invention.

[0163] Fig. 1, in a perspective view, illustrates a simple embodiment of a slewing ring bearing comprising an outer slewing ring and an inner slewing ring, and where each of the outer slewing ring and the inner slewing ring are formed as one singular piece;

[0164] Fig. 2A, in an exploded perspective view, shows a slewing ring bearing, according to embodiments of the invention, and which may be assembled according to an embodiment of a method according to another aspect of the invention, the slewing ring bearing comprising an outer slewing ring, and an inner slewing ring, which inner slewing ring comprises a first inner slewing ring part and a second inner slewing ring part; Fig. 2B, in a sectional side view, show parts of the slewing ring bearing of Fig. 2A, in a partly assembled state, where the second inner slewing ring part of the inner slewing ring has been laterally displaced relative to a position where it is concentrically arranged relative to the outer slewing ring of the slewing ring bearing, and relative to the first inner slewing ring part;

[0165] Fig. 2C, in a partially sectional side view, shows the parts of the slewing ring bearing in a state during insertion of radial bearing balls, and where the second inner slewing ring part has been laterally (radially) displaced relative to a concentric position with the outer slewing ring ;

[0166] Fig. 2D, in a partially sectional side view, shows the parts of the slewing ring bearing of Fig. 2F, where the second inner slewing ring part has been displaced to a position where it is concentrically arranged relative to the outer slewing ring of the slewing ring bearing;

[0167] Fig. 2E, in a partially sectional side view, shows the parts of the slewing ring bearing of Fig. 2D in an assembly stage during arrangement of a bearing cage / radial bearing cage;

[0168] Fig. 2F, in a perspective view, shows the slewing ring bearing of Figs. 2A-2E in an assembled state, and with section removed to view the internal arrangement of the component parts;

[0169] Fig. 3, in a perspective view, shows a slewing ring bearing according to another embodiment of the present invention, with a cut-out to show the interior, and further illustrating a step in an assembly method thereof;

[0170] Fig. 4, in a perspective view, illustrates an embodiment of the slewing ring bearing comprising a cylindrical flange attached to the first inner slewing ring part, Fig. 5, in a perspective view, illustrates an embodiment of the slewing ring bearing, where an axial bearing comprises a axial tapered roller bearing row with tapered roller or conical rollers;

[0171] Fig. 6, in a perspective view, illustrates an embodiment of the slewing ring bearing, where the axial bearing comprises axial rollers, and the radial bearing comprises radial rollers;

[0172] Fig. 7, in a perspective view, illustrates an embodiment of the slewing ring bearing, where an intermediate inner slewing ring part is arranged between the first inner slewing ring part and the second inner slewing ring part, and where the axial bearing comprises rollers of the needle-type and where both the slewing ring bearing further comprises a radial roller bearing and a radial angular contact ball bearing;

[0173] Fig. 8, in a perspective view, illustrates an embodiment of the slewing ring bearing comprising two axial bearings between the first inner slewing ring part and the outer slewing ring, one axial ball bearing and one axial angular contact ball bearing, an where the radial bearing between the second inner slewing ring part and the outer slewing ring is a radial angular contact ball bearing;

[0174] Fig. 9, in a perspective view, illustrates an embodiment of the slewing ring bearing, the first inner slewing ring part being formed with a gear ring;

[0175] Fig. 10, in a perspective view, illustrates an embodiment of the slewing ring bearing comprising a stepper motor ring;

[0176] Fig. 11 , in a perspective view, illustrates another embodiment the slewing ring bearing comprising a stepper motor ring; and

[0177] Fig 12, in a perspective view, illustrates an embodiment the slewing ring bearing, where the slewing ring bearing comprises a gear mechanism driven by gear motors, an encoder ring, conductive rings and conductive contact; and Fig. 13, in a perspective view, illustrates an embodiment of the slewing ring bearing comprising a first inner slewing ring part comprising both an axial ball bearing row and a radial roller bearing row; and

[0178] Fig. 14, in a perspective view, illustrates an embodiment of the slewing ring bearing comprising a first inner slewing ring part comprising both an axial ball bearing row and a radial roller bearing row.

[0179] Detailed description of the embodiments

[0180] The present invention refers to slewing ring bearings 42, such a slewing ring bearing 42 as shown in in Fig. 2F, and to a method of assembling such a slewing ring bearing 42,. In Fig. 2F, the slewing ring bearing 42 is shown with a section cut-out in order to show, the interior of the slewing ring bearing 42.

[0181] However, first we turn to Fig. 1 to explain a simpler embodiment of a slewing ring bearing 42.

[0182] The slewing ring bearing 42 shown in Fig. 1 comprises an outer slewing ring 1, and an inner slewing ring 2.

[0183] In general, slewing ring bearings 42 of this type further comprises at least one row of axial bearing elements and at least one row of radial bearing elements. In the embodiment shown in Fig. 1, the bearing elements are provided as bearing balls, axial bearing balls 3 and radial bearing balls 4.

[0184] As is apparent from Fig. 1 the outer slewing ring 1 comprises a first wall part T and a second wall part 1”. The first wall part T of the outer slewing ring 1 is ring-shaped and defines a plane, P. The second wall part 1” of the outer slewing ring 1 comprises a cylindrical portion, which is formed perpendicular to the plane defined by the first wall part T.

[0185] The outer slewing ring 1 is configured as a single integrated unit formed in one piece. Thus, the first wall part 1 ’ and a second wall part 1 ” of the outer slewing ring 1 are as a single integrated unit formed in one piece. This could also be referred to as the outer slewing ring 1 being solid.

[0186] In connection with the present invention the outer slewing ring 1 is solid and provided with an axial bearing race 7, and a radial bearing race 8.

[0187] The slewing ring bearing 42 further comprises at least one inner slewing ring 2.

[0188] The outer slewing ring 1 functions as a hollow shell, in which the axial and radial bearing rows are arranged upon the inner axial and radial sides / surfaces.

[0189] One surface of the first wall T of the outer slewing ring 1 , which surface faces towards the inner slewing ring 2, comprises an axial bearing race 7, which corresponds to an axial bearing race 7 on the inner slewing ring 2, in the sense that the two races are arranged opposite to and facing each other.

[0190] Another surface provided on the second wall part 1” of the outer slewing ring 1 , which surface faces towards the inner slewing ring 2, comprises a radial bearing race 8, which corresponds to a radial bearing race 8 on the inner slewing ring 2, in the sense that the two races are arranged opposite to and facing each other.

[0191] The respective rows of bearing elements 3, 4 are provided between the respective pairs of axial and radial bearing races 7, 8.

[0192] As can be appreciated in e.g. Fig. 1 , an outer diameter of the inner slewing ring 2 is larger than an inner diameter of the outer slewing ring 1 . Thereby, the inner slewing ring 2 is prevented from passing through the ring-shaped outer slewing ring 1 , and is thereby locked in one axial direction when assembled. Further, the second wall part 1” of the outer slewing ring 1 prevents movement in the radial direction when the slewing ring bearing has been assembled.

[0193] When the slewing ring bearing is assembled the row of radial bearing elements, radial bearing balls 4, allows receiving radial thrust, and is further being capable of both receiving axial moment thrust, and locking the inner slewing ring 2 and the outer slewing ring 1 together. Thus, the row of radial bearing elements forms at least a part of a lock for connecting the inner slewing ring 2 and the outer slewing ring 1 .

[0194] This arrangement of the slewing ring bearing 42 allows for easy installment of bearing elements between the inner slewing ring 2 and the outer slewing ring 1 and thereby decreases the manufacturing time of the slewing ring bearing 42.

[0195] During assembly of the slewing ring bearing 42, first an axial bearing row is installed towards the axial bearing race of the outer slewing ring. The further assembly process may vary, but an inner slewing ring is installed together with a radial bearing row. The radial bearing row is of a kind, which will help to lock the inner slewing ring in place, within the outer shell.

[0196] The bearing races of each of the inner and outer bearing rings 2, 1 will always be concentric as they are integrated in the same solid body.

[0197] The solid outer slewing ring 1 is a compact, strong and cheap solution, which will provide for a very robust slewing ring bearing 42.

[0198] Further, the design of outer slewing ring 1 of the slewing ring bearing 42 as a single integrated body, which is not kept together by fasteners, allows for using less material, compared to extra material thickness around fasteners. The absence of fasteners is a strong advantage when a compact construction is needed.

[0199] The solid outer slewing ring 1 further benefits in relation to tolerances since the absence of fasteners reduces complexity of assembly. Tolerances are in general of high importance regarding bearings and slewing rings. Turning now to Figs. 2A-F, the slewing ring bearing 42 according to the invention will be described in more detail. An assembled version of the slewing ring bearing 42 is shown in Fig. 2F. Fig. 2A shows an exploded view of the same.

[0200] As was the case with the slewing ring bearing 42 of Fig. 1 , the slewing ring bearing 42 of the embodiment in Figs. 2A-F, at least comprises an outer slewing ring 1 and an inner slewing ring 2, where an axial bearing 200 and a radial bearing 300, both of which are arranged between the inner outer slewing ring 1 and the inner slewing ring 2.

[0201] An important difference is that the inner slewing ring 2 comprises two inner slewing ring parts, a first inner slewing ring part 19 and a second inner slewing ring part 20.

[0202] In the general case the inner slewing ring 2 may comprise more that the two inner slewing ring parts, but only two are shown in Figs. 2A-F. In embodiments, where the inner slewing ring 2 may comprise more than the two inner slewing ring parts, these one or more additional inner slewing ring parts are formed between the first inner slewing ring part 19 and the second inner slewing ring part 20 as intermediate inner slewing ring parts 21 (not shown in Figs. 2A-F).

[0203] In the general case and as shown in the embodiment of Figs. 2A-F, an axial bearing 200 of the slewing ring bearing 42 is always provided between the outer slewing ring 1 and the first inner slewing ring part 19, and a radial bearing 300 is always provided between the outer slewing ring 1 and the second inner slewing ring part 20. The slewing ring bearing 42 may comprise further bearing rows, provided between the outer slewing ring 1 and one of the first inner slewing ring part 19, the second inner slewing ring part 20, or any intermediate inner slewing ring parts 21.

[0204] The axial bearing 200 may be of many different types as described in further detail and exemplified below. The axial bearing 200 shown in Fig. 2F is of a type with bearing balls 3 arranged in a bearing cage (also sometimes referred to simply as a cage), axial bearing cage 5. Below, such axial bearings 200 and other types of axial bearings 200 will be described in further detail. The radial bearing 300 is of a type comprising bearing elements inserted between bearing races, for example in the form of bearing balls 4, as shown in Figs. 2A-F, or conical or cylindrical rollers as exemplified in further detail below. The bearing balls 4 as shown in Figs. 2A-F could also be referred to as radial bearing balls 4. The radial bearing 300 shown in Fig. 1 is of a type with bearing ball 4 arranged in a bearing cage, radial bearing cage 6. Below, such radial bearings 300 will be described in further detail.

[0205] The inner slewing ring 2 is configured for fitting within the outer slewing ring 1. It can also be said that the outer slewing ring and the inner slewing are both configured such that the inner slewing ring 2 is configured for fitting within the outer slewing ring 1.

[0206] When the axial bearing 200 and the radial bearing 300 is provided, the inner slewing ring 2 and the outer slewing ring 1 are connected to each other, such that rotation there between is allowed.

[0207] The axial bearing 200 is provided between mutually facing surfaces of the outer slewing ring 1 and the first inner slewing ring part 19 of the inner slewing ring 1. These mutually facing surfaces extend generally perpendicular to the axial direction of the slewing ring bearing 42, or at least at an angle to the axial direction.

[0208] The radial bearing 300 is formed between mutually facing lateral surfaces of the outer slewing ring 1 and the second inner slewing ring part 20 of the inner slewing ring 2. By lateral surfaces are meant surfaces extending in the axial direction of the slewing ring bearing 42, i.e. in the axial direction of the outer slewing ring 1 and the inner slewing ring 2. It will be appreciated that these surfaces are cylindrical surfaces. These cylindrical surfaces of the outer slewing ring 1 and the inner slewing ring 2 are concentric when the slewing ring bearing 42 is in an assembled state.

[0209] It will further be appreciated that the outer slewing ring 1 , the first inner slewing ring part 19 and the second inner slewing ring part 20 are concentric when the slewing ring bearing 42 is in an assembled state, for example as shown in Fig. 2F. The outer slewing ring 1 may be ring-shaped. The outer slewing ring 1 comprises a first wall part T and a second wall part 1”. The first wall part T is ring-shaped and defines a plane, P. The second wall part 1” may also be ring shaped. The second wall part 1” comprises a cylindrical portion, which is formed perpendicular to the plane P defined by the first wall part T.

[0210] The first wall part T may be generally plate shaped. The first wall part T preferably has a larger extend in the radial direction (in the plane, P), than in the axial direction of the outer slewing ring 1.

[0211] The second wall part 1”, as mentioned, has a cylindrical shape. The second wall part 1” preferably has a larger extend in the axial direction than in the radial direction (in the plane, P) of the outer slewing ring 1.

[0212] In preferred embodiments, and as shown the first wall part T and the second wall part 1” of the outer slewing ring 1 is formed as a singular piece, i.e. as a single integrated unit.

[0213] The inner slewing ring 2 is ring-shaped. Thus, the first inner slewing ring part 19 and the second inner slewing ring part 20 are ring-shaped. Further, any intermediate inner slewing ring parts 21 will be ring shaped. The inner slewing ring 2 is formed such that it has one surface, a first surface 2’, which is an axial end surface of the first inner slewing ring part 19 and one radially outer surface, second surface 2” which is cylindrical and extends in the axial direction of the inner slewing ring 2, in particularly the second inner slewing ring part 20.

[0214] When the inner slewing ring 2 and the outer slewing ring 1 are assembled to form a slewing ring bearing 42, the first surface 2’ of the first inner slewing ring part 19 faces the first wall part T of the outer slewing ring 1. In the embodiment shown in Figs. 2A-F, the first surface 2’ of the second inner slewing ring part 20 can be said to define a plane P2, which, when the first inner slewing ring part 19, the second inner slewing ring part 20 and the outer slewing ring 1 are assembled to form a slewing ring bearing 42 is parallel to the plane P defined by the first wall of the outer slewing ring 1. Further, when the inner slewing ring 2 and the outer slewing ring 1 are assembled to form a slewing ring bearing 42, the second surface 2” of the second inner slewing ring part 20 faces the second wall part 1” of the outer slewing ring 1. Further, when the inner slewing ring 2 and the outer slewing ring 1 are assembled to form a slewing ring bearing 42, the cylindrical second surface 2” of the inner slewing ring 2 is concentric to the cylindrical second wall part 1” of the outer slewing ring 1.

[0215] An outermost diameter of at least the first inner slewing ring part 19 of the inner slewing ring 2 is larger than an inner diameter of the outer slewing ring 2. Thereby the first wall T of the outer slewing ring and the first surface 2’ of the inner slewing ring will abut on each other, for example via any axial bearing elements 3, 12, 14, to prevent movement in the axial direction towards each other.

[0216] As shown in Figs. 2A-F, the axial bearing 200 may - as also mentioned above - comprise bearing elements in the form of (axial) bearing balls 3. The axial bearing 200 shown in Figs. 2A-F is of a type with bearing balls 3 arranged in a cage, axial bearing cage 5.

[0217] However, in other embodiments, the axial bearing 200 may be of other types.

[0218] For example the axial bearing 200 may comprises bearing elements in the shape of rollers 12, 14, 37. Such rollers may be arranged in bearing cages 5 as well.

[0219] Examples of slewing ring bearings 42 having cylindrical rollers 12 in the axial bearing 200 is shown in Figs. 6 and 7. Fig. 7 shows an example of the cylindrical roller 37 being of the needle-type.

[0220] In some embodiments the bearing elements may be conical rollers 14. An example, where the axial bearing 200 comprises conically shaped rollers 14 is shown in Figs.5 and 12. In such embodiments, it will be appreciated that the first surface 2’ of the first inner slewing ring part 19 of the inner slewing ring 2 and / or the mutually facing surface of the first wall T of the outer slewing ring 1 need not be planar, but may be provided by conical surfaces. In yet other embodiments, the radial bearing 200 may be provided by sliding bearings or other types of bearings described herein (not shown).

[0221] Turning now to Figs. 2B-F, a method of assembling a slewing ring bearing 42 according to an embodiment of the invention will be described. The method comprises a number of steps.

[0222] In a first step the first inner slewing ring part 19 of the inner slewing ring 2 is arranged in the outer slewing ring 1 , while providing an axial bearing 200 there between.

[0223] When, as shown in Figs. 2A-F, the axial bearing 200 comprises a row of bearing balls / axial bearing balls 3 arranged in a bearing cage 5 / axial bearing cage 5, the bearing cage 5 with the bearing balls 3 is simply arranged in abutment with the first wall T of the outer slewing ring 1 or with the first surface 2’ of the first inner slewing ring part 19. Then the opposite of the outer slewing ring 1 or the first inner slewing ring part 19 is arranged in abutment with the ball bearings 3 in the bearing cage 5. The same approach is possible with rollers 12, 14, 37, of e.g. the types referred to above, when these rollers are provided in an axial bearing cage 5.

[0224] In this case, whether the axial bearing cage 5 comprises bearing balls 3 or rollers 12, 14, 37, both of the first surface 2’ of the first inner slewing ring part 19 and the first wall T of the outer slewing ring 1 may be provided with suitable matching bearing races, as exemplified below.

[0225] Alternatively, to the axial bearing balls 3 or axial bearing rollers 12, 14, 37 being arranged in an axial bearing cage 5 before arranging against the first surface 2’ of the first inner slewing ring part 19 or the first wall T of the outer slewing ring 1, the axial bearing balls 3 or axial bearing rollers 12, 14, 37 may be arranged on a bearing race of the first surface 2’ of the first inner slewing ring part 19 or the first wall T of the outer slewing ring 1 , whereafter the bearing elements 3, 12, 14, 37 are distributed equidistantly along the bearing race. Then, a bearing cage / axial bearing cage 5 may be snapped to the bearing elements to secure their position relative to each other.

[0226] In the embodiment shown in Figs 2A-F, the axial bearing 200 is provided with an groove axial bearing race 7 on the first wall T of the outer slewing ring 1 and another groove axial bearing race 7 arranged on the first surface 2’ of the inner ring 2.

[0227] In this case of the embodiment shown in Figs. 2A-F, the method of assembly comprises a step (not shown) of installing the axial bearing 200 comprising the axial balls 3 provided in a bearing cage 5, between the axial bearing race 7 (in the form of a groove axial bearing race 7) on the outer slewing ring 1 and the axial bearing race 7 (in the form of a grove axial bearing race 7) on the first inner slewing ring part 19. The result of this step or steps is shown in Fig. 2B.

[0228] The groove axial bearing races 7 of the axial bearing 200 secures that the first inner slewing ring 19 is concentrically arranged relative to the outer slewing ring 1 , when the inner and or outer slewing rings are not manipulated.

[0229] In Fig. 2B however, also a second inner slewing ring part 20 has been placed in abutment with the first inner slewing ring part 19.

[0230] In Fig. 2B the second inner slewing ring part 20 on the first inner slewing ring part 19 is radially displaced relative to the outer slewing ring 1 and relative to the first inner slewing ring part 19.

[0231] When the axial bearing 200 and the radial bearing 300 (see below) has been established, the second inner slewing ring part 20 is supposed to be concentrical relative to the outer slewing ring 1 and relative to the first inner slewing ring part 19, such as it is shown in Fig. 2D and 2E. In this situation, the inner slewing ring 2, a gap, concentric gap 137, is provided between the outer slewing ring 1 and the second inner slewing ring 20. The concentric gap 137 is ring-shaped and has a uniform width along its circumference. The concentric gap 137 is thus provided between the outer slewing ring 1 and the second inner slewing ring 20 when these are assembled. The width of the concentric gap 137 is smaller than a diameter of a radial bearing ball 4 or the diameter of a radial bearing roller 22.

[0232] In a subsequent step to arranging the second inner slewing ring part 20 in abutment with the first inner slewing ring part 19, and as shown in Fig. 2B-C, the second inner slewing ring part 20 is displaced in a radial direction relative to the outer slewing ring 1. The radial direction may also be referred to as a sideways or lateral direction, and therefore, the displacement of the second inner slewing ring part 20 relative to the outer slewing ring 1 in the radial direction may also be referred to as lateral displacement or sideways direction.

[0233] The displacement of the second inner slewing ring part 20 relative to the outer slewing ring 1 in the radial direction creates a temporary larger width gap 138 lateral to one side of the second inner slewing ring part 20 and the outer slewing ring 1 , while the concentric gap 137 opposite to the temporary larger width gap 138 is reduced to a temporarily reduced width gap 139. The temporary larger width gap 138 may also be referred to as a loading gap 140 when it reaches it’s maximum size.

[0234] In Figs. 2B-C the loading gap 140 is shown to the left in the figure, and the temporarily reduced width gap 139 is shown to the right.

[0235] The creation of the loading gap 140 between the outer slewing ringl and the second inner slewing ring part 20 allows insertion of radial bearing balls 4 into the radial bearing 300. This is illustrated in Fig. 2C. A suitable number of radial bearing balls is inserted into the radial bearing 300.

[0236] In the embodiment of the slewing ring bearing 42 shown in Figs. 2A-F, the radial bearing 300 is provided by a groove radial bearing race 8 formed on the second wall 1” of the outer slewing ring 1 , and a corresponding groove radial bearing race 8 formed on the second surface 2” of the second inner slewing ring part 20.

[0237] The radial bearing balls 4 are as shown in Fig. 2C in between the groove radial bearing race 8 formed on the second wall 1” of the outer slewing ring 1 , and the corresponding groove radial bearing race 8 formed on the second surface 2” of the second inner slewing ring part 20.

[0238] When a desired number of radial bearing balls 4 have been inserted between the grove radial bearing race 8 formed on the second wall 1” of the outer slewing ring 1, and the corresponding groove radial bearing race 8 formed on the second surface 2” of the second inner slewing ring part 20, the second inner slewing ring part 20 is displaced relative to the outer slewing ring 1 in the radial direction and towards the position, where the outer slewing ring 1 and the second inner slewing ring part 20 are concentrically arranged relative to each other. This will recreate the ring-shaped concentric gap 137 having uniform width along its circumference. This position is shown in Fig. 2D.

[0239] It will be appreciated that in this situation, all of the radial bearing balls 4 are located immediately adjacent to each other.

[0240] Then, in a not shown subsequent step, the radial bearing balls 4 are distributed along the circumference of the groove radial bearing race 8 formed on the second wall 1” of the outer slewing ring 1, and along the corresponding groove radial bearing race 8 formed on the second surface 2” of the second inner slewing ring part 20. The radial bearing balls 4 are distributed in such a manner that there is a regular equidistant spacing between them. Fig. 2E shows the situation where the radial bearing balls have been equidistantly distributed.

[0241] In a final step the, and as illustrated in Fig. 2E, a radial bearing cage 6 may be inserted between into the space between the groove radial bearing race 8 formed on the second wall 1” of the outer slewing ring 1, and the corresponding groove radial bearing race 8 formed on the second surface 2” of the second inner slewing ring part 20, in order to fix the radial bearing balls 4 in their equidistant position relative to each other.

[0242] Fig. 2E indicates the radial bearing cage 6 in two positions. In the top part of the figure, the radial bearing race 6 is indicated in the disassembled situation, and the arrow indicates the direction of movement into the position where the radial bearing cage 6 is inserted into the space between the groove radial bearing race 8 formed on the second wall 1” of the outer slewing ring 1 and the corresponding groove radial bearing race 8 formed on the second surface 2” of the second inner slewing ring part 20, where tongues 6’ between the radial bearing balls 4 are keeping the radial bearing balls 4 apart.

[0243] The radial bearing cage 6 is preferably a so-called crown-cage. It takes the form of a ring-shaped element with axially extending tongues 6’. The tongues 6’ are equidistantly arranged on the radial bearing cage 6. Between the tongues 6’, bearing ball receiving apertures 6” are formed. Each of the bearing ball receiving apertures 6” is configured to hold one radial bearing ball 4.

[0244] The radial bearing cage 6 may be formed in such a way and such a material that the tongues 6’ are resilient such that the bearing balls 4 may snap into a bearing ball receiving apertures 6”.

[0245] A similar type of radial bearing cage 6 may be used, when the radial bearing 300 is of a type using bearing elements in the form of bearing rollers 18, the radial bearing cage 6 being shaped and sized to receive, such rollers 18.

[0246] It will be appreciated that the step of distributing the radial bearing balls 4 in the space between the groove radial bearing race 8 formed on the second wall 1” of the outer slewing ring 1, and the corresponding groove radial bearing race 8 formed on the second surface 2” of the second inner slewing ring part 20, may be carried out by and / or when inserting the radial bearing cage 6 into the space between groove radial bearing race 8 formed on the second wall 1” of the outer slewing ring 1 , and the corresponding groove radial bearing race 8 formed on the second surface 2” of the inner slewing ring 2.

[0247] When the radial bearing cage 6 is correctly inserted, the radial bearing 300 is provided. Further, when the radial bearing cage 6 is correctly inserted, the bearing balls 4 are locked in the radial bearing 300, and further, the outer slewing ring and the inner slewing ring are prevented from moving apart. Thereby the slewing ring bearing 42 is locked in its assembled state. As a further step, axial and / and or radial bearing seals (not shown) may be installed.

[0248] It is important that in the side, i.e. in the loading gap 140, where the radial bearing balls 4 are loaded, the inner slewing ring 2 remains at level with - or preferably is capable of retracting from the radial bearing row, thereby ensuring that the slewing ring bearing 42 is capable of being assembled with a high number of radial bearing balls 4. This is obtained by the division of the inner slewing ring into two or more inner slewing ring parts 19, 20, and 21.

[0249] The first inner slewing ring part 19, and the second inner slewing ring part 20 comprises cooperating surfaces.

[0250] In some embodiments, and as shown the first inner slewing ring part 19, and the second inner slewing ring part 20 comprises cooperating planar or plain surfaces. The plain surface of the second inner slewing ring part 20 is arranged on the plain surface of the first inner slewing ring part 19.

[0251] The first inner slewing ring part 19 and the second inner slewing ring part 20 may have cooperating connecters 17, 17’, 17” such that the first inner slewing ring part 19 and the second inner slewing ring part 20 may be connected fixedly to each other. Such connectors 17 may be bores 17‘ in the first inner slewing ring part 19 and matching bores 17” in the second inner slewing ring part 20, allowing the first inner slewing ring part 19 and the second inner slewing ring part 20 to be connected to each other via suitable means such as a bolt or split, or other connectors known in the art.

[0252] In other (not shown) embodiments, other types of cooperating connecters 17 may be used.

[0253] In other (not shown) embodiments the surfaces of the first inner slewing ring part 19 and the second inner slewing ring part 20 facing each other may be provided with matching profiles, such that when the first inner slewing ring part 19 and the second inner slewing ring part 20 are in contact with each other, they will be rotationally fixed to each other.

[0254] In the embodiment of the slewing ring bearing 42 shown in Figs. 2A-F an outer diameter of the second inner slewing ring part 20, i.e. the diameter of the second surface 2” of the second inner slewing ring part 20, is smaller than the largest diameter of the first inner sewing ring part 19.

[0255] Fig. 3, in a perspective view, illustrates a slewing ring bearing 42 according to another embodiment. The slewing ring bearing 42 comprises an axial bearing 200 and a radial bearing 300. The slewing ring bearing 42 further comprises an outer slewing ring 1, and an inner slewing ring 2. The inner slewing ring 2 comprises two inner slewing ring parts, a first inner slewing ring part 19, and a second inner slewing ring part 20, just as the embodiment of the slewing ring bearing 42 described in connection with Figs. 2A-F above. The axial bearing 200 is provided between the first inner slewing ring part 19 and the first wall T of the outer slewing ring 1. The radial bearing 300 is provided between the second inner slewing ring part 20 and the second wall 1” of the outer slewing ring 1.

[0256] The axial bearing 200 is of the type having axial bearing balls 3 arranged between axial bearing races 7 of the groove type on both of the inner slewing ring 2 and the outer slewing ring, similar to what was described in connection with Figs. 2A-F above.

[0257] The slewing ring bearing 42 in the Fig. 3 embodiment differs from the embodiment in Figs. 2A-F in that the profile of the outer slewing ring 1 is differently shaped.

[0258] The slewing ring bearing 42 in the Fig. 3 embodiment differs from the embodiment in Figs. 2A-F in that the radial bearing 300 is of the type having radial bearing balls 4 arranged between radial angular contact bearing races 9, one on the outer slewing ring 1 and one on the second inner slewing ring part 20 of the inner slewing ring 2. An axial angular contact bearing race 11 is a rounded surface formed between two flat planer levels of the first surface 2’ of the inner ring 2. In some cases, axial angular contact bearing races 11 may comprise a depression

[0259] The Fig. 3 embodiment of the slewing ring bearing 42 further differs from the slewing ring bearing 42 shown in Figs. 2A-F in that an outer diameter of the second inner slewing ring part 20, i.e. the diameter of the second surface 2” of the second inner slewing ring part 20, is the same as the largest diameter of the first inner sewing ring part 19.

[0260] From this comparison between the Fig. 3 embodiment and the Figs. 2A-F of the slewing ring bearing 42 it will be appreciated that the two (or more) component inner slewing ring provides an increased flexibility to design a slewing ring bearing 42 in a compact manner with various types of bearing races and cooperating bearing elements, while at the same time ensuring that a large number of bearing elements may be arranged in the bearing races. A larger number of bearing elements provides for a more robust slewing ring bearing 42.

[0261] In the following and in connection with Figs. 4-12 a number of further embodiments of a slewing ring bearing 42 according to these principles of invention will be described.

[0262] Fig. 4, in a perspective view, illustrates an embodiment of the slewing ring bearing 42 comprising two separate inner slewing ring parts 19,20. Due to the geometries it is necessary for the inner slewing ring 19,20 to be able to slide apart during the assembly process. This enables the embodiment to achieve higher tolerances of the bearing rows 7, 9. When the separate inner slewing ring parts 19,20 are fixed in placed, they are combined by means cooperating connecters 17.

[0263] The axial bearing 200 is of the type having axial bearing balls 3 arranged between axial bearing races 7 of the groove type on both of the inner slewing ring 2 and the outer slewing ring, similar to what was described in connection with Figs. 2A-F and Fig. 3 above. The slewing ring bearing 42 in the Fig. 4 embodiment differs from the embodiment in Figs. 2A-F in that the radial bearing 300 is of the type having radial bearing balls 4 arranged between radial angular contact bearing races 9, one on the outer slewing ring 1 and one on the second inner slewing ring part 20 of the inner slewing ring 2.

[0264] The Fig. 4 embodiment of the slewing ring bearing 42 further differs from the slewing ring bearing 42 shown in Figs. 2A-F in that an outer diameter of the second inner slewing ring part 20, i.e. the diameter of the second surface 2” of the second inner slewing ring part 20, is the same as the largest diameter of the first inner sewing ring part 19.

[0265] In the Fig. 4 embodiment, the slewing ring bearing 42 further comprises a cylindrical flange 16 attached to the first inner slewing ring part 19, which cylindrical flange 16 extends through a central opening of the outer slewing ring 1. Such a cylindrical flange 16 may be utilized for example for mounting the slewing ring bearing 42 to another device. It is clear that when such a cylindrical flange 16 is formed integrally with the first inner slewing ring part 19, this may provide for a stronger connection than if the cylindrical flange 16 was a separate part to be mounted on the first inner slewing ring part 19. The number of steps of assembly is also reduced, when the cylindrical flange 16 is formed integrally with the first inner slewing ring part 19. However, it is also clear that when such a cylindrical flange 16 will prevent radial displacement of the first inner slewing ring part 19 relative to the outer slewing ring 1. Therefore, if the first inner slewing ring part 19 and the second inner slewing ring part 20 were not separate parts as opposed to one integral inner slewing ring 2, then the assembly would be prevented.

[0266] Fig. 5, in a perspective view, illustrates an embodiment of a slewing ring bearing 42 comprising an axial bearing 200 comprising bearing elements having a tapered shape, i.e. conical bearing rollers 14 (arranged in a bearing cage 5), and corresponding bearing races 15 formed on the first inner slewing ring part 19 and on the outer slewing ring 1. It is clear that the bearing races 15 will prevent radial movement between the first inner slewing ring part 19 and the outer slewing ring 1, when the bearing rollers 14 have been installed. Thus, the division of the inner slewing ring 2 into a first inner slewing ring part 19 and a second inner slewing ring part 20 is required in order to achieve assembly of the radial bearing 300 of the slewing ring bearing 42. The slewing ring bearing 42 is equipped with accesses for lubrication 32, and is showing a tall or long version of the slewing ring bearing 42.

[0267] Fig. 6, in a perspective view, illustrates an embodiment of a slewing ring bearing 42.

[0268] The slewing ring bearing 42 again comprises an inner slewing ring 2 comprising separate parts, first inner slewing ring part 19, and second inner slewing ring part 20. Upon assembly as described above, the first inner slewing ring part 19, and second inner slewing ring part 20 may be connected by means of cooperating connectors 17.

[0269] The slewing ring bearing 42 comprises an axial bearing 200 comprising bearing elements having a cylindrical shape, bearing rollers 12 (arranged in a bearing cage 5), and corresponding bearing races 13 of the groove-type formed on the first inner slewing ring part 19 and on the outer slewing ring 1.

[0270] The slewing ring bearing 42 further comprises a radial bearing 300, which also comprises bearing elements having a cylindrical shape, radial bearing rollers 18 (arranged in a bearing cage 6), and corresponding bearing races, radial roller bearing races 22, of the groove-type formed on the second inner slewing ring part 20 and on the outer slewing ring 1.

[0271] Again, it is clear that the axial bearing races 14 will prevent radial movement between the first inner slewing ring part 19 and the outer slewing ring 1, when the axial bearing rollers 12 have been installed. Thus, the division of the inner slewing ring 2 into a first inner slewing ring part 19 and a second inner slewing ring part 20 is required in order to achieve assembly of the radial bearing 300 of the slewing ring bearing 42.

[0272] The slewing ring bearing 42 is further equipped with flanges on the outer slewing ring having connecters 117 configured for connecting the slewing ring bearing 42 to another device. Further, the slewing ring bearing 42 is equipped with flanges on the second inner slewing ring part 20 having connecters 118 configured for connecting the slewing ring bearing 42 to another device.

[0273] Turning now to Fig. 7, illustrating, in a perspective view, an further embodiment of a slewing ring bearing 42.

[0274] Again, the slewing ring bearing 42 comprises an outer slewing ring 1 and an inner slewing ring 2. The inner slewing ring 2 comprises separate parts, a first inner slewing ring part 19, a second inner slewing ring part 20, and a third or intermediate inner slewing ring part 21. The intermediate inner slewing ring part 21 is arranged between the first inner slewing ring part 19 and the second inner slewing ring part 20. Upon assembly as described above, the first inner slewing ring part 19, the second inner slewing ring part 20 and the intermediate inner slewing ring part 21 may be connected by means of cooperating connectors 17.

[0275] The slewing ring bearing 42 comprises an axial bearing 200 comprising bearing elements having a cylindrical shape, axial bearing rollers 12 in the form of the axial needle rollers 37 (arranged in a bearing cage 5), and corresponding bearing races 13 of the groove-type formed on the first inner slewing ring part 19 and on the outer slewing ring 1.

[0276] The slewing ring bearing 42 further comprises a radial bearing 300 of the type having radial bearing balls 4 arranged between radial angular contact bearing races 9, one on the outer slewing ring 1 and one on the second inner slewing ring part 20 of the inner slewing ring 2.

[0277] Further, a second radial bearing 300 is provided between the intermediate inner slewing ring part 21 and the outer slewing ring 1. This second radial bearing 300 increases the strength of the slewing ring bearing 42. The second radial bearing 300 comprises bearing elements having a cylindrical shape, radial bearing rollers 18 (arranged in a bearing cage 6), and corresponding bearing races, radial roller bearing races 22, of the groove-type formed on the second inner slewing ring part 20 and on the outer slewing ring 1.

[0278] The intermediate inner slewing ring part 21 is inserted into the outer slewing ring 1 in the same manner as the second inner slewing ring part 20 is inserted in the embodiments described above. First the intermediate inner slewing ring part 21 is placed on the first inner slewing ring part 19 and radially displaced to create a loading gap 140 (not shown in Fig. 7). Then the bearing elements are inserted in the loading gap 140 (not shown in Fig. 7), and distributed equidistantly along the bearing race 22. Then the radial bearing cage 6 or other types of spaces is inserted to secure the equidistant spacing.

[0279] After the intermediate inner slewing ring part 21 and second radial bearing 300 has thus been arranged in the outer slewing ring 1, the second inner slewing ring part 20 is arranged adjacent to the intermediate inner slewing ring part 21 , in the same manner as described for the second inner slewing ring part 20 of any of the previously described embodiments.

[0280] Fig. 8, in a perspective view, illustrates an embodiment of a slewing ring bearing 42.

[0281] Again, the slewing ring bearing 42 comprises an inner slewing ring 2 comprising separate parts, a first inner slewing ring part 19, and a second inner slewing ring part 20. Upon assembly as described above, the first inner slewing ring part 19, and second inner slewing ring part 20 may be connected by means of cooperating connectors 17.

[0282] In this embodiment the slewing ring bearing 42 comprises two axial bearings 200, both provided between the first inner slewing ring part 19 and the outer slewing ring 1. An inner axial bearing 200 comprises axial bearing balls 3 arranged in bearing cages 5 and groove axial bearing races 7. An outer axial bearing 200 comprises axial bearing balls 3 arranged in bearing cages 5 and axial angular contact bearing races 11. Further, a second inner slewing ring part 20 is provided against said outer slewing ring 1 with a radial bearing comprising radial bearing balls 4 arranged in a radial bearing cage 6, and angular contact bearing races 9.

[0283] The embodiment is further provided with a flange 38, extending radially from an inner circumference of the first wall 1 ’ of the outer slewing ring 1 , to achieve higher strength and shielding of the inner one of the two axial bearings 200.

[0284] Fig. 9, in a perspective view, illustrates an embodiment of a slewing ring bearing 42.

[0285] Again, the slewing ring bearing 42 comprises an inner slewing ring 2 comprising separate parts, a first inner slewing ring part 19, and a second inner slewing ring part 20. Upon assembly as described above, the first inner slewing ring part 19, and second inner slewing ring part 20 may be connected by means of cooperating connectors 17, 17’, 17”.

[0286] In this embodiment the slewing ring bearing 42 comprises an axial bearings 200, provided between the first inner slewing ring part 19 and the outer slewing ring 1, where the axial bearing 200 comprises axial bearing balls 3 arranged in bearing cages 5 and groove axial bearing races 7.

[0287] Further, a second inner slewing ring part 20 is provided against said outer slewing ring 1 with a radial bearing comprising radial bearing balls 4 arranged in a radial bearing cage 6, and angular contact bearing races 9.

[0288] As in the Fig. 8 embodiment, the Fig. 9 embodiment is further provided with a cylindrical flange 38 extending radially from an inner circumference of the first wall T of the outer slewing ring 1 , in to achieve higher strength and in order to shield the axial bearing 200.

[0289] The slewing ring bearing 42 further comprises a row of gear teeth extending radially outward from the first inner slewing ring part 19. The row of gear teeth constitutes a gear ring 27. The gear ring 27, as shown in Fig. 9 may preferably be formed integrally with the first inner slewing ring part 19.

[0290] The gear ring 27 may interact with a transmission gear 47 (not shown in Fig. 9, see e.g. Fig.12) through an opening provided through the second wall 1” of the outer slewing ring 1.

[0291] Fig. 10, in a perspective view, illustrates an embodiment of a slewing ring bearing 42.

[0292] In this embodiment, the slewing ring bearing 42 comprises one axial bearings 200, and one radial bearing 300.

[0293] The axial bearing 200 comprises axial bearing balls 3 arranged in bearing cages 5 and axial angular contact bearing races 11.

[0294] The slewing ring bearing 42 has one radial bearing 300 of the type having radial bearing balls 4 arranged between radial angular contact bearing races 9, one on the outer slewing ring 1 and one on the second inner slewing ring part 20 of the inner slewing ring 2.

[0295] In this embodiment, the slewing ring bearing 42 further comprises a stepper motor ring.

[0296] The stepper motor ring comprises magnet rotor rings 33, and a row of electric stator coils 34.

[0297] The first inner slewing ring part 19 is provided with a permanent magnet rotor ring 33.

[0298] The outer slewing ring 1 is provided with a suitable series of electric stator coils 34 to facilitate the stepper movement of the permanent magnet rotor ring 33. The series of electric stator coils 34 are provided on an inward surface of the second wall 1” of the outer slewing ring 1.

[0299] The stator coils 34 may be connected in an electric circuit (not shown), and which is controlled by a motor controller (not shown).

[0300] Fig. 11 , in a perspective view, illustrates an embodiment of a slewing ring bearing 42, which is similar to the embodiment in Fig. 10, but with some differences.

[0301] Again, in this embodiment, the slewing ring bearing 42 comprises one axial bearings 200, and one radial bearing 300.

[0302] The axial bearing 200 comprises axial bearing balls 3 arranged in bearing cages 5 and groove axial bearing races 7, differing from the angular contact bearing races 11 in the Fig. 10 embodiment.

[0303] The slewing ring bearing 42 has one radial bearing 300 of the type having radial bearing balls 4 arranged between radial angular contact bearing races 9, one on the outer slewing ring 1 and one on the second inner slewing ring part 20 of the inner slewing ring 2.

[0304] Also in this Fig. 11 embodiment, the slewing ring bearing 42 further comprises a stepper motor ring, and the stepper motor ring comprises magnet rotor rings 33, and a row of electric stator coils 34. But here the magnet rotor rings 33, and the electric stator coils 34 are reversed between the outer slewing ring 1 and first inner slewing ring part 19.

[0305] Thus, the first inner slewing ring part 19 is provided with a suitable series of electric stator coils 34 to facilitate the stepper movement of the permanent magnet rotor ring 33.

[0306] The outer slewing ring 1 is provided with a permanent magnet rotor ring 33. The permanent magnet rotor ring 33 is provided on an inward surface of the second wall 1 ” of the outer slewing ring 1. The stator coils 34 may be connected in an electric circuit (not shown), and which is controlled by a motor controller (not shown).

[0307] Fig. 12, in a perspective view, illustrates an embodiment of a slewing ring bearing 42. Again, the slewing ring bearing 42 comprises an inner slewing ring 2 comprising separate parts, a first inner slewing ring part 19, and a second inner slewing ring part 20. Upon assembly as described above, the first inner slewing ring part 19, and second inner slewing ring part 20 may be connected by means of cooperating connectors 17, 17’, 17”.

[0308] Also in this embodiment, the slewing ring bearing 42 comprises one axial bearings 200, and one radial bearing 300.

[0309] Like the Fig. 5 embodiment, the axial bearing 200 comprises bearing elements having a tapered shape, i.e. conical bearing rollers 14 (arranged in a bearing cage 5), and corresponding bearing races 15 formed on the first inner slewing ring part 19 and on the outer slewing ring 1.

[0310] Further, the slewing ring bearing 42 has one radial bearing 300 of the type having radial bearing balls 4 arranged between radial angular contact bearing races 9, one on the outer slewing ring 1 and one on the second inner slewing ring part 20 of the inner slewing ring 2.

[0311] The outer slewing ring 1 is provided with a row of gear teeth, in gear ring 27. The gear ring 27 is arranged on the inner radial surface of the outer slewing ring 1 between the axial bearing 200 and the radial bearing 300, the row of gear teeth pointing in an inward radial direction.

[0312] The gear ring 27 may interact with one or as shown, two transmission gears 47 through openings provided through the first inner slewing ring part 19.

[0313] Each transmission gear 47 is driven by a gear motor 48, and thereby may control the rotation direction of the inner assembly comprising the inner slewing ring 2, and further components 28,30, described below. Each motor 48 may be controlled by a motor controller (not shown) which again may be controlled by a micro controller computer (not shown).

[0314] Further, the slewing ring bearing 42 comprises an encoder ring 28, provided on a radially outward surface of the first inner slewing ring part 19, between the axial bearing 200 and the radial bearing 300. The encoder ring 28 comprises a pattern (not shown) of a suitable kind. The outer slewing ring 1 comprises an opening 29 for a sensor to be able to read the position of the encoder ring 28. The sensor may thereby be able to read the rotational direction of the inner slewing ring 2 relative to the outer slewing ring 1.

[0315] Further, the slewing ring bearing 42 comprises conductive slip rings 30. The first inner slewing ring part 19 is, in the axial direction, provided with a set of conductive slip rings 30 for the purpose of conducting electric current and / or signal to and from the inner slewing ring 2 from the outer slewing ring 1 through conductive contact 31. For interaction by gear transmission (not shown), encoder reader (not shown) and conductive contacts 31 to the components 27,28,30 of the inner slewing ring 2, the outer slewing ring 1 is provided with an opening 29.

[0316] Figure 13, in a perspective view, illustrates another embodiment of a slewing ring bearing 42.

[0317] In this embodiment, the slewing ring bearing 42 comprises an axial bearing 200, a radial roller bearing 18 and a radial bearing 300.

[0318] The axial bearing 200 comprises axial bearing balls 3 arranged in bearing cages 5 and axial groove bearing races 7.

[0319] A first inner slewing bearing part 19 comprises an axial bearing 200 comprising axial bearing balls 3 arranged in bearing cages 5 and axial groove bearing races 7. Further, the first inner slewing bearing part 19 comprises a radial roller bearing arranged between a second surface 2” of the first inner slewing ring part 19 and the second wall 1” of the outer slewing ring part 1. The radial roller bearing race 22 of the outer slewing ring 1 is of the groove kind.

[0320] Further, the slewing ring bearing 42 has one radial bearing 300 of the type having radial bearing balls 4 arranged between radial groove bearing races 8, one on the outer slewing ring 1 and one on the second inner slewing ring part 20 of the inner slewing ring 2.

[0321] The embodiment is particularly advantageous as the radial roller bearing 18 is directly installed with the axial ball bearing. Allowing for a maximum number of radial rollers 18. Thus, making the embodiment particularly strong in the radial direction.

[0322] Figure 14, in a perspective view, illustrates yet another an embodiment of a slewing ring bearing 42.

[0323] The embodiment is similar to the one of figure 13, however the groove part of the radial roller bearing races 22 are provided to the first inner slewing ring part 2,19. Thus allowing for a more compact design.

[0324] It is to be noted that the figures and the above description have shown the example embodiments in a simple and schematic manner. Many of the specific mechanical details have not been shown since the person skilled in the art should be familiar with these details and they would just unnecessarily complicate this description.

[0325] List of parts

[0326] 1 outer slewing ring

[0327] 1 ’ first wall part of outer slewing ring

[0328] 1” second wall part of outer slewing ring

[0329] 2 inner slewing ring

[0330] 2’ first surface of inner slewing ring, which is an end surface of the inner slewing ring

[0331] 2” second surface of inner slewing ring, radially outer surface

[0332] 3 axial bearing element in the form of an axial bearing ball

[0333] 4 radial bearing element in the form of a radial bearing ball

[0334] 5 axial bearing cage

[0335] 6 radial bearing cage

[0336] 7 axial bearing race

[0337] 8 radial bearing race

[0338] 9 radial angular contact bearing race

[0339] 10 plain axial bearing race

[0340] 11 axial angular contact bearing race

[0341] 12 axial bearing element in the form of an axial bearing roller

[0342] 13 axial roller bearing race

[0343] 14 axial bearing element in the form of an axial tapered bearing roller

[0344] 15 axial tapered roller bearing race

[0345] 16 cylindrical flange

[0346] 17 means of fastening

[0347] 18 radial bearing element in the form of a radial bearing roller

[0348] 19 first inner slewing ring part / first part of inner slewing ring

[0349] 20 second inner slewing ring part / second part of inner slewing ring

[0350] 21 third inner slewing ring part / third part of inner slewing ring, or intermediate inner slewing ring part

[0351] 22 Radial roller bearing race

[0352] 23 Radial tapered bearing roller

[0353] 24 Radial tapered roller bearing race

[0354] 27 Gear ring

[0355] 28 Encoder ring 29 Opening in outer slewing ring

[0356] 30 Conductive slip ring

[0357] 31 Conductive contact

[0358] 32 Access for lubrication

[0359] 33 Rotor ring with permanent magnet

[0360] 34 Stator coil unit

[0361] 35 Combined inner and outer slewing ring

[0362] 36 Load bracket for inner slewing ring

[0363] 37 Axial needle roller

[0364] 38 Constructional flange

[0365] 39 Caster wheel system

[0366] 40 Wheel

[0367] 41 Wheel fork

[0368] 42 Slewing ring bearing

[0369] 43 Wheel hub

[0370] 44 Hollow wheel hub embodiment of the present invention

[0371] 45 Combined inner slewing ring and wheel fork

[0372] 46 Wheel motor

[0373] 47 Transmission gear

[0374] 48 Gear motor

[0375] 137 concentric gap, provided between the outer slewing ring and at least the second inner slewing ring part, when the two are concentrically arranged, the gap is ring-shaped and has a uniform width along its circumference

[0376] 138 temporary larger width gap, lateral to one side of the second inner slewing ring part and the outer slewing ring, same as loading gap

[0377] 139 reduced width gap, formed opposite to the temporary larger width gap when second inner slewing ring part is radially displaced

[0378] 140 loading gap

[0379] 142 plain axial bearing race

[0380] 200 axial bearing

[0381] 300 radial bearing

Claims

Claims1. A slewing ring bearing (42) comprising- an outer slewing ring (1),- an inner slewing ring (2) configured for fitting within the outer slewing ring (1),- an axial bearing (200) provided between mutually facing surfaces of the outer slewing ring (1) and the inner slewing ring (2), which surfaces face in an axial direction of the slewing ring bearing (42), and- a radial bearing (300) formed between mutually facing lateral surfaces of the outer slewing ring (1) and the inner slewing ring (2), wherein the outer slewing ring (1) comprises a first wall part (T) and a second wall part (1”), wherein the first wall part (1’) is ring-shaped, and comprises a surface which faces in the axial direction slewing ring bearing (42), wherein the second wall (1”) part comprises a cylindrical portion extending in the axial direction of the slewing ring bearing (42), wherein the first wall part T and a second wall part 1” of the outer slewing ring 1 are formed as a single integrated unit formed in one piece, wherein an outmost diameter of the inner slewing ring (2) is larger than an inner diameter of the outer slewing ring (1), wherein the inner slewing ring (2) comprises- a first inner slewing ring part (19), and- a second inner slewing ring part (20), wherein the axial bearing (200) is provided between the first inner slewing ring part (19) and the first wall (T) of the outer slewing ring (1 ) and wherein the radial bearing (300) is provided between the second inner slewing ring part (20) and the second wall (1”) of the outer slewing ring (1).

2. The slewing ring bearing (42) according to claim 1, wherein the first inner slewing ring part (19) and the second inner slewing ring part (20) comprises cooperating connectors (17, 17’, 17”) formed on the first inner slewing ring part (19) and on the second inner slewing ring part (20), the cooperating connectors (17, 17’, 17”) beingconfigured for fixedly connecting the first inner slewing ring part (19), and the second inner slewing ring part (20) fixed to each other.

3. The slewing ring bearing (42) according to claim 1, wherein a surface of the first inner slewing ring part (19) and a surface of the second inner slewing ring part (20) facing each other may be provided with matching profiles, such that when the first inner slewing ring part (19) and the second inner slewing ring part (20) are abutting each other, they will be rotationally fixed to each other.

4. The slewing ring bearing (42) according to any one of the claims 1-3, wherein the axial bearing (200) comprises axial bearing balls (3) arranged between the mutually facing radially facing surfaces of first inner slewing ring part (19) and the outer slewing ring (1).

5. The slewing ring bearing (42) according to claim 4, wherein the axial bearing (200) further comprises a groove axial bearing race (7) formed on the first inner slewing ring part (19) and a corresponding groove axial bearing race (7) formed on the outer slewing ring (1).

6. The slewing ring bearing (42) according to claim 4, wherein the axial bearing (200) further comprises an axial angular contact bearing race (11) formed on the first inner slewing ring part (19) and a corresponding axial angular contact bearing race (11) formed on the outer slewing ring (1).

7. The slewing ring bearing (42) according to any one of the claims 1-3, wherein the axial bearing (200) comprises axial bearing rollers (12) arranged between the mutually facing radially facing surfaces of first inner slewing ring part (19) and the outer slewing ring (1).

8. The slewing ring bearing (42) according to claim 7, wherein the axial bearing (200) further comprises an axial roller bearing race 13 formed on the first inner slewing ring part (19) and a corresponding axial roller bearing race 13 formed on the outer slewing ring (1).

9. The slewing ring bearing (42) according to any one of the claims 1-8, wherein the radial bearing (300) comprises radial bearing balls (4) arranged between the mutually facing radially facing surfaces of the second inner slewing ring part (20) and the outer slewing ring (1).

10. The slewing ring bearing (42) according to claim 9, wherein the radial bearing (300) further comprises a groove radial bearing race (8) formed on the second inner slewing ring part (20) and a corresponding groove radial bearing race (8) formed on the outer slewing ring (1).

11. The slewing ring bearing (42) according to claim 9 or 10, wherein the radial bearing (300) further comprises a radial angular contact bearing race (9) formed on the second inner slewing ring part (20) and a corresponding radial angular contact bearing race (9) formed on the outer slewing ring (1).

12. The slewing ring bearing (42) according to any one of the claims 1-8, wherein the radial bearing (300) comprises radial bearing rollers (18) arranged between the mutually facing radially facing surfaces of the second inner slewing ring part (20) and the outer slewing ring (1).

13. The slewing ring bearing (42) according to claim 12, wherein the radial bearing (300) further comprises a radial roller bearing race (22) formed the second inner slewing ring part (20) and a corresponding axial roller bearing race 13 formed on the outer slewing ring (1).

14. The slewing ring bearing (42) according to any one of the claims 1-13, wherein the inner slewing ring (2) further comprises an intermediate inner slewing ring part (21), formed between the first inner slewing ring part (19) and the second inner slewing ring part (20).

15. The slewing ring bearing (42) according to claim 14, wherein the intermediate inner slewing ring part (21) comprises a second radial bearing (300).

16. A method of assembling a slewing ring bearing (42), the slewing ring bearing (42) comprising- an outer slewing ring (1),- an inner slewing ring (2) configured for fitting within the outer slewing ring (1),- an axial bearing (200) provided between mutually facing surfaces of the outer slewing ring (1) and the inner slewing ring (2), which surfaces face in an axial direction of the slewing ring bearing (42), and- a radial bearing (300) formed between mutually facing lateral surfaces of the outer slewing ring (1) and the inner slewing ring (2), wherein the outer slewing ring (1) comprises a first wall part (T) and a second wall part (1”), wherein the first wall part (1’) is ring-shaped, and comprises a surface which faces in the axial direction slewing ring bearing (42), wherein the second wall (1”) part comprises a cylindrical portion extending in the axial direction of the slewing ring bearing (42), wherein the first wall part T and a second wall part 1” of the outer slewing ring 1 are formed as a single integrated unit formed in one piece, wherein an outmost diameter of the inner slewing ring (2) is larger than an inner diameter of the outer slewing ring (1), wherein the inner slewing ring (2) comprises- a first inner slewing ring part (19), and- a second inner slewing ring part (20), wherein the axial bearing (200) is provided between the first inner slewing ring part (19) and the first wall (T) of the outer slewing ring (1 ) and wherein the radial bearing (300) is provided between the second inner slewing ring part (20) and the second wall (1”) of the outer slewing ring (1), wherein the method comprises the steps of:- arranging the first inner slewing ring part (19) in the outer slewing ring (1), while providing an axial bearing (200) there between,- arranging a second inner slewing ring part (20) in the outer slewing ring (1)- displacing the second inner slewing ring part (20) in a radial direction relative to the outer slewing ring (1), thereby providing a temporary loading gap (140)between the second inner slewing ring part (20) and the outer slewing ring (1), which loading gap (140) is dimensioned to receive a radial bearing ball (4),- entering a plurality of radial bearing elements (4, 18) through the loading gap (140) into the radial bearing (300),- sliding the second inner slewing ring part (20) in a radial direction and relative to the outer slewing ring (2) to a concentric position of the outer slewing ring (1) and the inner slewing ring (2),- distributing the radial bearing elements (4, 18) equidistantly in the radial bearing (300), and- inserting one or more radial bearing element (4, 18) distributers for securing an even distribution of the plurality of bearing elements (4, 18) in the radial bearing (300).

18. The method according to claim 17, further comprising a step of adding an axial bearing seal (25) to the axial bearing (200) and / or adding a radial bearing seal (26) to the radial bearing (300).

19. The method according to claim 17 or 18, wherein the step of inserting one or more radial bearing ball distributers for securing an even distribution of the plurality of bearing elements (4, 18) in the radial bearing (300) comprises inserting a radial bearing cage (6).

20. The method according to claim 19, wherein the radial bearing cage (6) is a crown bearing cage.

21. The method according to any one of the claims 17-20, wherein the inner slewing ring (2) further comprises an intermediate inner slewing ring part (21), formed between the first inner slewing ring part (19) and the second inner slewing ring part (20), and wherein the method comprises the step, before inserting the second inner slewing ring part (20) into the outer slewing ring (1), inserting an intermediate inner slewing ring part (21) into the outer slewing ring (1).

Images