A patent by the inventors Gruber, Andreas
(Maria Buch-Feistritz, AT); Swete, Wolfgang (Knittelfeld, AT); Ovize, Pascal
(Chitry-le-fort, FR); Tanke, Jesko-Henning (Schweinfurt, DE); Fick, Ake
(Landskrona, SE), filed on October 9, 2009, was published online on December 24,
2013, according to news reporting originating from Alexandria, Virginia, by
VerticalNews correspondents.
Patent number 8613557 is assigned to Aktiebolaget SKF (Goteborg, SE).
The following quote was obtained by the news editors from the background information supplied by the inventors: "The present invention relates to the field of seals used in the rolling bearings, and more particularly in the rolling bearings operating in an aggressive outdoor environment due to the presence of various kinds of pollution, such as splashing water, dust and other foreign matter, to the exposition of the ultraviolet radiation emitted by the sun, and to the variations of temperature.
"This is notably the case of the rolling bearings used in a wind turbine in order to angularly orient the rotor of the turbine according to the direction of the wind.
"Otherwise, in the case of rolling bearings, and more specifically in the case of large-sized rolling bearings used for instance in such wind turbine, each time the bearing is lubricated, there is a high increase in the pressure inside the bearing. During this operation, the pressure may raise to 0.4 MPa. Thus, there is a risk that the surplus grease will be ejected from the bearing at the location of the seals. In the case of large-sized rolling bearings, pressure relief valves arc provided to allow this surplus grease to be ejected. Nonetheless, the surplus grease does sometimes escape from the bearing via the seals rather than through these valves.
"However, there are numerous applications in which an escape of grease through the bearing seals must be reliably avoided, both during the lubricating of the bearings, i.e. while the interior of the bearings is being pressurized, and during normal running of the bearings, even in the case of relative movements that the two rings may do in addition to the rotational movements, under the action of the loads on the bearing. Such relative movements of the rings are relatively important more especially as the rolling bearing has a large diameter.
"With the aim of avoiding this drawback, document FR-A-2 778 954 discloses a sealing arrangement for a rolling bearing comprising at least one row of rolling elements between first and second rings which are concentric and radially separated from one another by an annular space. This arrangement comprises at least an elastic seal fixed to the first ring and exhibiting a lip pressing against a bearing surface situated on the second ring inside the annular space. The lip of the seal is shaped in such a way that the force with which it presses against the bearing surface increases with the pressure inside the bearing.
"With such a sealing arrangement, the lip opposes effectively any escape of grease, not only during lubrication but also during normal running of the bearing.
"However, the sealing arrangement disclosed in this document has the drawback of being force fitted into a groove formed on the inner ring of the rolling bearing in order to obtain its retaining on the ring. This is detrimental in terms of mounting time and of cost."
In addition to the background information obtained for this patent, VerticalNews journalists also obtained the inventors' summary information for this patent: "One aim of the present invention is to overcome the aforementioned drawback.
"It is a particular object of the present invention to provide a rolling bearing having at least a seal which is easy to install, which prevents grease from escaping from the bearing, even under the effect of a raised pressure inside the bearing, and which also prevents the ingress of moisture, dust and other bodies.
"A further object to the present invention is to provide a rolling bearing having good wear and aging resistances.
"Another object to the present invention is to provide a large-sized rolling bearing adapted for a wind turbine.
"In one embodiment, the rolling bearing comprises an inner ring, an outer ring, at least one row of rolling elements and at least one seal provided between the outer and inner rings. The seal has, in cross section, the overall shape of a H. The seal comprises internal lips and external lips of the seal forming the two substantially parallel branches of the H. The inner and outer rings comprise opposite radial ribs located axially between the internal and external lips to axially retain the seal.
"Preferably, the internal and external lips of the seal are resiliently coupled in the axial direction with the radial ribs.
"In one embodiment, the axial thickness of the radial ribs is larger than the axial gap between the internal lips and the external lips in a free state of the joint in order to keep in a permanent contact the seal and the ribs by elasticity.
"Advantageously, the seal is freely moveable in the circumferential direction relative to the inner ring and/or the outer ring.
"The internal lips can exhibit an outwardly curved profile so that only the free ends of the lips press against retaining surfaces of the ribs. The retaining surfaces of the ribs are substantially perpendicular to the rotational axis of the bearing.
"In one embodiment, the radial ribs define an annular passage narrowing inwardly in direction of the rolling elements.
"Preferably, the seal has hardness equal to or greater than 90 shore A. Advantageously, the seal is formed from thermoplastic urethane (TPU) liner. The seal can also be formed from metal. The seal can also comprise both a metallic material and a plastic material such as the TPU.
"At least the internal lips each comprise advantageously, on their external side, a protrusion axially extending towards the external lips.
"The ribs may be integrally formed with the inner and outer rings, or be separate bodies. The ribs can comprise on their outer surfaces a coating.
"The invention also relates to a manufacturing method of a seal for a rolling bearing in which the seal is manufactured in the form of a band and is then cut to the desired length, and in which the ends of the seal are heated in order to weld them, the seal being rolled on itself with the ends placed end-to-end to obtain an annular seal.
"In another embodiment, the seal is adapted to a rolling bearing comprising an inner ring, an outer ring, and at least one row of rolling elements between the outer and inner rings. The seal has, in cross section, the overall shape of a H and comprises internal lips and external lips forming the two branches of the H. The internal and external lips are connected each other. The seal is formed from metal.
"In another embodiment, the seal is adapted to a rolling bearing comprising an inner ring, an outer ring, and at least one row of rolling elements between the outer and inner rings. The seal has, in cross section, the overall shape of a H and comprises internal lips and external lips forming the two branches of the H. At least the internal lips each comprise, on their external side, a protrusion axially extending towards the external lips.
"The invention also relates to an assembly method of a seal inside a rolling bearing comprising an inner ring, an outer ring, at least one row of rolling elements between the outer an inner rings, and opposite radial ribs provided on the ribs, wherein the seal having in cross section the overall shape of a H is axially pushed between the inner and outer rings, a first branch of the H being radially deformed inwards and passing through an annular passage defined by the ribs. The seal is still axially pushed until a second branch of the seal bears against the ribs, the first branch recovering by elasticity its initial shape.
"The seal may be axially pushed between the rings in order that the first branch of the H bears against the ribs, the branch being then radially deformed inwards. Alternatively, the first branch of the H is radially deformed inwards by means of a tool before the seal is axially pushed between the ring."
Patent number 8613557 is assigned to Aktiebolaget SKF (Goteborg, SE).
The following quote was obtained by the news editors from the background information supplied by the inventors: "The present invention relates to the field of seals used in the rolling bearings, and more particularly in the rolling bearings operating in an aggressive outdoor environment due to the presence of various kinds of pollution, such as splashing water, dust and other foreign matter, to the exposition of the ultraviolet radiation emitted by the sun, and to the variations of temperature.
"This is notably the case of the rolling bearings used in a wind turbine in order to angularly orient the rotor of the turbine according to the direction of the wind.
"Otherwise, in the case of rolling bearings, and more specifically in the case of large-sized rolling bearings used for instance in such wind turbine, each time the bearing is lubricated, there is a high increase in the pressure inside the bearing. During this operation, the pressure may raise to 0.4 MPa. Thus, there is a risk that the surplus grease will be ejected from the bearing at the location of the seals. In the case of large-sized rolling bearings, pressure relief valves arc provided to allow this surplus grease to be ejected. Nonetheless, the surplus grease does sometimes escape from the bearing via the seals rather than through these valves.
"However, there are numerous applications in which an escape of grease through the bearing seals must be reliably avoided, both during the lubricating of the bearings, i.e. while the interior of the bearings is being pressurized, and during normal running of the bearings, even in the case of relative movements that the two rings may do in addition to the rotational movements, under the action of the loads on the bearing. Such relative movements of the rings are relatively important more especially as the rolling bearing has a large diameter.
"With the aim of avoiding this drawback, document FR-A-2 778 954 discloses a sealing arrangement for a rolling bearing comprising at least one row of rolling elements between first and second rings which are concentric and radially separated from one another by an annular space. This arrangement comprises at least an elastic seal fixed to the first ring and exhibiting a lip pressing against a bearing surface situated on the second ring inside the annular space. The lip of the seal is shaped in such a way that the force with which it presses against the bearing surface increases with the pressure inside the bearing.
"With such a sealing arrangement, the lip opposes effectively any escape of grease, not only during lubrication but also during normal running of the bearing.
"However, the sealing arrangement disclosed in this document has the drawback of being force fitted into a groove formed on the inner ring of the rolling bearing in order to obtain its retaining on the ring. This is detrimental in terms of mounting time and of cost."
In addition to the background information obtained for this patent, VerticalNews journalists also obtained the inventors' summary information for this patent: "One aim of the present invention is to overcome the aforementioned drawback.
"It is a particular object of the present invention to provide a rolling bearing having at least a seal which is easy to install, which prevents grease from escaping from the bearing, even under the effect of a raised pressure inside the bearing, and which also prevents the ingress of moisture, dust and other bodies.
"A further object to the present invention is to provide a rolling bearing having good wear and aging resistances.
"Another object to the present invention is to provide a large-sized rolling bearing adapted for a wind turbine.
"In one embodiment, the rolling bearing comprises an inner ring, an outer ring, at least one row of rolling elements and at least one seal provided between the outer and inner rings. The seal has, in cross section, the overall shape of a H. The seal comprises internal lips and external lips of the seal forming the two substantially parallel branches of the H. The inner and outer rings comprise opposite radial ribs located axially between the internal and external lips to axially retain the seal.
"Preferably, the internal and external lips of the seal are resiliently coupled in the axial direction with the radial ribs.
"In one embodiment, the axial thickness of the radial ribs is larger than the axial gap between the internal lips and the external lips in a free state of the joint in order to keep in a permanent contact the seal and the ribs by elasticity.
"Advantageously, the seal is freely moveable in the circumferential direction relative to the inner ring and/or the outer ring.
"The internal lips can exhibit an outwardly curved profile so that only the free ends of the lips press against retaining surfaces of the ribs. The retaining surfaces of the ribs are substantially perpendicular to the rotational axis of the bearing.
"In one embodiment, the radial ribs define an annular passage narrowing inwardly in direction of the rolling elements.
"Preferably, the seal has hardness equal to or greater than 90 shore A. Advantageously, the seal is formed from thermoplastic urethane (TPU) liner. The seal can also be formed from metal. The seal can also comprise both a metallic material and a plastic material such as the TPU.
"At least the internal lips each comprise advantageously, on their external side, a protrusion axially extending towards the external lips.
"The ribs may be integrally formed with the inner and outer rings, or be separate bodies. The ribs can comprise on their outer surfaces a coating.
"The invention also relates to a manufacturing method of a seal for a rolling bearing in which the seal is manufactured in the form of a band and is then cut to the desired length, and in which the ends of the seal are heated in order to weld them, the seal being rolled on itself with the ends placed end-to-end to obtain an annular seal.
"In another embodiment, the seal is adapted to a rolling bearing comprising an inner ring, an outer ring, and at least one row of rolling elements between the outer and inner rings. The seal has, in cross section, the overall shape of a H and comprises internal lips and external lips forming the two branches of the H. The internal and external lips are connected each other. The seal is formed from metal.
"In another embodiment, the seal is adapted to a rolling bearing comprising an inner ring, an outer ring, and at least one row of rolling elements between the outer and inner rings. The seal has, in cross section, the overall shape of a H and comprises internal lips and external lips forming the two branches of the H. At least the internal lips each comprise, on their external side, a protrusion axially extending towards the external lips.
"The invention also relates to an assembly method of a seal inside a rolling bearing comprising an inner ring, an outer ring, at least one row of rolling elements between the outer an inner rings, and opposite radial ribs provided on the ribs, wherein the seal having in cross section the overall shape of a H is axially pushed between the inner and outer rings, a first branch of the H being radially deformed inwards and passing through an annular passage defined by the ribs. The seal is still axially pushed until a second branch of the seal bears against the ribs, the first branch recovering by elasticity its initial shape.
"The seal may be axially pushed between the rings in order that the first branch of the H bears against the ribs, the branch being then radially deformed inwards. Alternatively, the first branch of the H is radially deformed inwards by means of a tool before the seal is axially pushed between the ring."
(4-traders)
