ROLLING BEARING

Abstract: The improvement prevents fast ageing and oxidising of the lubricant in a standard rolling bearing. These objectives are achieved by applying, adjacent the seal member (6), an annular member (5) having magnetic properties and being provided with pockets or (small) reservoirs (8) filled with the magnetic lubricant. Due to this arrangement a "fresh" quan­ tity of lubricant will always be available to provision the pre­ sent lubricant in the bearing.

Description: The invention concerns a rolling bearing comprising at least one outer race and at least one inner race situated coaxially therein and at least one row of rolling members situated in the annular space between the races, and generally annular seals with sealing rings for sealing off from the surroundings, on either side of the rolling members, said annular space between said races wherein a lubricant is present which lubricant is a magnetic fluid and means forming a magnetic field. Such a rolling bearing is disclosed by the Journal Mechanical Engineering vol.97, no 4, April 1975, pages 30 and 31. In rolling bearings of this type the violent movements, to which such lubricant between the rolling members is subjected, produce heat of friction with, as a result, an increase of the temperature within the bearing, causing the lubricant to age more rapidly and become oxidized. In addition, these violent movements of the lubricant affect the structure of it, owing to which the lubricant rapidly looses its properties and may ultimately break down entirely between the parts lubricated, causing the temperature to become still higher. The solution to this problem has hitherto been sought in a limitation of the quantity of lubricant, but a smaller quantity on the other hand may result in lubricant failure and an increase in the content of metal particles worn off into the lubricant. The object of the invention is to produce an improved bearing of the type mentioned wherein the abovementioned problems are solved in another effective way. This object is accomplished in that in the inwardly directed sides of the sealing rings at least one cavity is provided and that the magnetic field forming means has poles on either side of said cavity, near the races, so as to retain the lubricant therein. In a rolling bearing designed in this way each cavity forms a lubricant reservoir wherein, owing to the magnetic fields, the lubricant in the form of a magnetic fluid is confined, while at the same time these magnetic fields ensure that the proper quantity of lubricant is always found between the contacting parts of the rolling members and the races. An exchange of the quantity of active lubricant from a reservoir is obtained by the continuous evaporation and condensation of the lubricant, so that in the course of time the total quantity of lubricant within a reservoir will be consumed. Further, an additional advantage is that any metal particles worn off would be retained within the cavities by the magnetic fields, so that such particles are unable to enter the sensitive contact areas. The sealing rings are preferably designed as magnets forming the magnetic fields, of which one pole is situated in the inner peripheral area and the other pole in the outer peripheral area. Advantageously to at least one of the sealing rings there is attached a sealing member having a sealing lip and behind said lip, between the sealing ring and the facing race there is present a quantity of sealing magnetic fluid. A magnetic fluid is known per se and consists of a colloidal suspension of extremely small particles, in the order of magnitude of 7-10 µm, of a material having paramagnetic properties, usually magnetized, in a fluid consisting mostly of a hydrocarbon, these particles being clad with a thin layer of a material that prevents flocculation of the particles. The particles normally move constantly in the fluid as a result of thermal agitation and Brownian movement, but when such a magnetic fluid is located in a magnetic field the particles orient themselves in essentially one direction, whereby the fluid acts like soft iron. The invention is explained in detail with the aid of the drawing, wherein a portion of the rolling bearing pursuant to the invention is shown in axial cross section. As shown in the drawing, the rolling bearing comprises an outer race 1 and an inner race 2 situated coaxially therein, and a row of rolling members 3 situated between the race 1 and 2, which are kept apart by the cage 4. The annular space 12 between the races 1 and 2 is sealed off on either side of the rolling members 3 by the sealing rings 5, 5′ and the seals 6, 6′, of an elastomeric material, attached thereto, which comprise the sealing lips 7, 7′ that rest springily against the inner race 2. The sealing rings 5, 5′ are designed as magnets with the north and south poles illustrated, so that magnetic fields are formed, the lines of force of which are indicated by A and B. In the inwardly directed sides of the sealing rings 5, 5′ is formed a plurality of cavities 8, 8′, wherein a lubricant 11 in the form of a magnetic fluid is confined by the magnetic fields A, B. In addition, in the inner peripheral areas, directed toward the race 2, of the sealing ring 5, 5′ are formed cavities 9, 9′, while in the slot between the sealing rings 5, 5′ and the race 2 a quantity of sealing magnetic fluid 10, 10′ is present.

Claims: 1. Rolling bearing comprising at least one outer race (1) and at least one inner race (2) situated coaxially therein and at least one row of rolling members (3) situated in the annular space (12) between the races, and generally annular seals (5,6;5′6′) with sealing rings (5,5′) for sealing off from the surrondings, on either side of the rolling members, said annular space between said races wherein a lubricant (11) is present which lubricant is a magnetic fluid and means forming a magnetic field characterized in that in the inwardly directed sides of the sealing rings (5,5′) at least one cavity (8,8′) is provided and that the magnetic field forming means has poles on either side of said cavity, near the races, so as to retain the lubricant (11) therein. 2. Rolling bearing according to claim 1, characterized in that the sealing rings (5,5′) are designed as magnets forming the magnetic fields, of which one pole (S) is situated in the inner peripheral area and the other pole (N) in the outer peripheral area. 3. Rolling bearing according to claim 1 or 2, characterized in that to at least one of the sealing rings (5,5′) there is attached a sealing member (6,6′) having a sealing lip (7,7′) and behind said lip, between the sealing ring (5,5′) and the facing race (2), there is present a quantity of sealing magnetic fluid (10,10′).

Inventors: GABELLI, ANTONIO
Applicants: SKF INDUSTRIAL TRADING & DEVELOPMENT COMPANY B.V.
Application year: 1987
Main classification: F16C33
IPC codes: F16C33, F16J15