FR3036752A1 - AERONAUTICAL BEARING FOR PIVOT SYSTEM AND AIRCRAFT PROVIDED WITH SUCH A BEARING - Google Patents

Abstract

The invention relates to an aircraft bearing (10) comprising an outer ring (14) and an inner ring (16) between which is defined a rolling chamber (22) for rolling elements (18), and lubricant (20) provided in the rolling chamber (22). The inventors propose that the lubricant (20) is provided in the form of an oil saturated polymeric matrix which fills all the free space in the rolling chamber (22).

Description

BACKGROUND OF THE INVENTION The invention relates to an aeronautical bearing for a pivoting system and to an aircraft equipped with such a bearing. It is known to use aeronautical bearings in aircraft comprising pivoting elements such as adjustable surfaces or control elements, for example rudders, adjustable stabilizing surfaces, fins or blade feet. The requirements for the aeronautical bearings are very high not only for safety reasons but also for the parameters of their environment in the application, including for the most contaminated environments with very large temperature fluctuations. In addition, the need for visual checks or minimal maintenance must be taken into account. In order to maximize the maintenance intervals, the aeronautical bearings are generally equipped with lubricant channels. These lubricant channels may reduce the stability of the components, which must be compensated for by additional equipment, require space and must themselves be controlled and maintained.

Lubricant losses from bearings in contact with the environment are polluting and lubricants in control surface bearings or landing gear are often contaminated with de-icing agents. In applications with small frequent oscillations with amplitudes below the critical bearing angle, the bearing may leave the track's re-lubrication regime by the adjacent rolling elements and, consequently, show increase of its friction torque and premature wear on its tracks, following dry contacts.

It is these drawbacks that the invention intends to remedy by proposing an aeronautical bearing for a pivoting system, comprising an outer ring 3036752 and an inner ring between which is defined a rolling chamber for rolling elements, and lubricant provided in the rolling elements chamber.

According to an advantageous aspect of the invention, the lubricant is provided in the form of an oil saturated polymeric matrix which essentially fills all the free space in the rolling chamber. The oil can exit the die directly at the point of contact between the rolling elements and the bearing tracks and can avoid premature wear on its tracks as a result of dry contacts due to small oscillations, i.e. . below the critical angle of the bearing. The critical angle of the bearing is defined as the angle of rotation for which the trajectories of rolling elements on the tracks touch but do not overlap.

Thanks to the invention, the maintenance cycles can be prolonged, lubricant channels can be avoided and the durability of the bearing can be increased, particularly in applications of low frequent oscillations with amplitudes below the angle. critical of the bearing.

Preferably, such an oil saturated polymeric matrix fills all the free space in the bearing, surrounding the rolling elements and the cage (s). The porous structure of the polymer retains the lubricating oil through its millions of micropores. The pores are so small that they retain the oil in the material by its surface tension. As the oil filled polymeric material is injected into the bearing, a very small gap is formed around the rolling elements and tracks which allow the bearing components to rotate freely. Such matrices are known as "Solid Oil". When the die 30 slides against the rolling elements or tracks of a bearing, the metal is covered with a uniform and consistent film of oil. A slight increase in the operating temperature then causes the oil to rise towards the surface of the polymer matrix. This oil flow inside the polymer matrix occurs because the coefficient of thermal expansion of the oil is greater than that of the matrix and because the viscosity of the oil decreases as the temperature increases. increases. When the bearing stops rotating, the polymer matrix absorbs excess oil. A bearing with Solid Oil can hold two to four times more oil than the standard 5 grease lubricated bearings because the bearing is fully filled with Solid Oil, while a greased bearing normally works with about a third of its free space filled with fat. The standard oil used for Solid Oil is a high quality synthetic oil that meets the needs of most applications. Oils with other viscosities and characteristics are also available.

Since the polymer matrix fills the entire bearing, it is difficult for solid or liquid pollutants to reach the internal surfaces of the bearing, even in the absence of seals. However, in highly contaminated environments, it is possible to use friction seals in combination with the polymer matrix filled with the oil.

According to another advantageous but not compulsory aspect of the invention, neither the outer ring nor the inner ring has a lubrication channel. This provides the required stability while reducing weight.

Preferably, the polymeric matrix separates the rolling elements and thus has the function of a cage. The flexibility of the polymeric matrix results in attenuation in vibrating environments. In preferred embodiments, the rolling elements are rollers or needles. Another aspect of the invention relates to an aeronautical pulley comprising an aeronautical bearing as described above.

Other advantageous aspects of the invention relate to a system comprising a pivoting element supported by an aeronautical bearing as described hereinabove or by a pulley as described above or an aircraft comprising such a system. Preferably, the pivoting element is a fin or a rudder.

The invention will be better understood and other advantages thereof will appear more clearly in the light of the following description given by way of non-limiting example with reference to the accompanying drawings in which: FIG. 1 is a view exploded of an aeronautical bearing according to the invention; Figure 2 is a roller equipped with a bearing according to the invention in an exploded view; Figure 3 is a sectional view of an aeronautical bearing according to another embodiment of the invention; Fig. 4 is a schematic graph of the angle of rotation of an airplane wing for an intercontinental flight cycle; and Figure 5 is a graph of a load torque for several tested bearings. Figure 1 is an exploded view of an aeronautical bearing 10 according to the invention.

The aeronautical bearing 10 is adapted for use in a guide roller for control surfaces or flaps of a wing of an aircraft. Figure 2 is a pulley 12 equipped with a bearing 10 according to another embodiment of the invention in an exploded view.

The bearing 10 has an outer ring 14 and an inner ring 16 between which is defined a rolling chamber 22 for rolling elements 18 in the form of needles. A lubricant 20 is provided in the form of a saturated polymeric matrix of oil which fills all the free space in the rolling chamber 22. As external lubrication during the life of the bearing is no longer necessary, nor the outer ring 14 and the inner ring 16 does not include a lubrication channel. In addition, the bearing 16 has no metal cage since the polymer matrix separates the rolling elements 18. FIG. 3 is a sectional view of an aeronautical bearing 10 according to another embodiment of the invention. invention. The bearing 10 is a bearing for use in an actuator of a fin in which the rolling elements 18 are toroidal rollers. Fig. 4 is a schematic diagram of the rotation angle of the bearing 12 according to Fig. 3 for an intercontinental flight cycle. The fin is rotated a few times with rotation angles of the order of 25 ° during take-off and landing and hundreds of times with rotation angles of around 3 ° for the rest of the flight.

FIG. 5 is a schematic diagram of a load torque for several tested bearings. The solid line represents the starting torque of a bearing according to the invention as a function of the number of flight cycles. The mixed line represents the starting torque of a standard bearing greased according to the prior art as a function of the number of flight cycles. The standard greased bearing 20 was regreased after 2400 and 4800 flight cycles. It turns out that the bearing according to the invention has a service life comparable to that of the standard bearing even without re-lubrication. In the examples described above, the rolling elements are rollers or needles. However, it could also be marbles.

Claims (8)

REVENDICATIONS1. An aeronautical bearing comprising an outer ring (14) and an inner ring (16) between which is defined a rolling chamber (22) for rolling elements (18), and lubricant (20) provided in the rolling chamber ( 22), characterized in that the lubricant (20) is provided in the form of an oil-saturated polymeric matrix which fills the entire free space in the rolling chamber (22). Aeronautical bearing according to claim 1, characterized in that neither the outer ring (14) nor the inner ring (16) has a lubrication channel. Aeronautical bearing according to one of the preceding claims, characterized in that the polymer matrix separates the rolling elements (18). Aeronautical bearing according to one of the preceding claims, characterized in that the rolling elements (18) are rollers. Aeronautical bearing according to one of claims 1 to 3, characterized in that the rolling elements (18) are needles. Aircraft pulley comprising an aircraft bearing according to one of the preceding claims. System comprising a pivoting element supported by an aeronautical bearing according to one of claims 1 to 5 or a pulley according to claim 6. Aircraft comprising a system according to claim 7.