Self-lubricating spherical plain bearing

Abstract

The present invention relates to a self-lubricating ball joint (1) comprising a ball (2) and a cage (3), the ball being rotatably mounted within the cage (3), characterized in that the cage (3) is a one-piece molded product and includes a first laminate (31) consisting of several layers of composite material, the composite material comprising a self-lubricating composite including a woven fabric and a resin impregnated into the woven fabric.

Description

[Technical Field]

[0001] The present invention relates to the technical field of self-lubricating joints, and in particular to self-lubricating ball joints used in guiding rotating mechanical systems.

[0002] The invention applies more particularly to all types of ball joints requiring greaseless operation, i.e. operating with self-lubricating operation, and operating under substantial loads in dynamic mode.

[0003] The invention can be used in particular within the scope of axle systems, transmission systems. [Background technology]

[0004] A ball joint connection generally consists of a ball and a cage, with a spherical contact surface between the ball and the cage, which can have certain characteristics, such as being self-lubricating or allowing some play between the ball and the cage.

[0005] One of the constraints that arise in the manufacture of ball joints is the placement of the ball in the cage. Therefore, it is known to use a deformable cage, which takes the form of a part with mechanical weaknesses or consists of several parts, to make it possible to place the ball in the cage. The placement of the ball in the cage can therefore be carried out according to different known ball joint principles, which are described below. - The cage consists of two parts that screw around the ball. - The split cage is assembled by applying force together with the balls. - The cage has a notch that allows the ball to fit inside when installed. - The cage is formed on the ball by cold working.

[0006] Patent Document 1 describes a self-lubricating ball joint that includes a ball and a cage, where the ball is made of metal and rotatably mounted within the cage. The cage of this self-lubricating ball joint is formed from several parts, with a metal inner part pressed onto the ball, an elastomeric part placed on the metal inner part, and an outer part pressed onto the elastomeric part, so that the cage surrounds the ball.

[0007] A drawback of such self-lubricating ball joints is that installation is limited by the need to provide cage components that can be cold-worked sufficiently to properly enclose the ball. This inevitably reduces the mechanical strength of the steel cage due to its high deformability, but also leaves behind play that is difficult to control. This ball joint also complicates assembly by requiring crimping and elastomer curing operations to limit play in the assembled self-lubricating ball joint. The elastomer system's low shear strength can limit the movement of the ball joint.

[0008] Furthermore, such ball joints are constructed from materials that are susceptible to corrosion, which can be problematic when the ball joints are used in some applications where corrosion is a factor. Maintenance or replacement of ball joints installed in a system can also incur substantial costs and system downtime.

[0009] US Pat. Nos. 5,699,239 and 5,749,663 describe a ball joint comprising a ball movably mounted in a cage, both elements of which are made of metal. The cage is here formed as a single piece. The ball comprises several weakened zones arranged on its edge, which enable it to deform and thus be housed within the cage.

[0010] The drawback of such ball joints is that the deformability of the balls causes mechanical weakness in weakened zones and leaves play that is difficult to control. Furthermore, such ball joints consist of balls and cages made from materials that are susceptible to corrosion, which puts the ball joint at risk of rapid wear.

[0011] Patent document 4 describes a ball joint in which the ball and cage are made of composite material. However, such a ball joint has several drawbacks. First of all, the friction surface consists of a single layer of self-lubricating material and therefore inevitably contains weak zones at the joints between the edges of the fabric. Furthermore, the ball and cage are made of resin reinforced with glass filaments, a material with relatively limited mechanical strength in view of the stresses to which such a ball joint is subjected during operation.

[0012] Therefore, there is a need for improvements to the current state of the art to at least partially overcome the shortcomings of the prior art. [Prior art documents] [Patent documents]

[0013] [Patent Document 1] European Patent No. 1608881 [Patent Document 2] International Publication No. 2014 / 169942 Brochure [Patent Document 3] European Patent No. 2986862 [Patent Document 4] European Patent No. 0969217 Summary of the Invention [Problem to be solved by the invention]

[0014] The present invention relates to a self-lubricating ball joint comprising a ball and a cage, wherein the ball is rotatably mounted within the cage, and the cage is a single-piece molded article and includes a first laminate composed of multiple layers of a composite material, the composite material including a self-lubricating composite including a woven fabric and a resin impregnated into the woven fabric.

[0015] A cage comprising a laminate of several layers of composite material, including a self-lubricating composite, forming an integral volume, makes it possible to obtain self-lubricating contact between the cage and the balls without having weakening points or mounting directions, such as specific orientations associated with break lines, as in the prior art for split cages, or due to the location of the notches, as in the prior art for notched cages, and makes it possible to improve mechanical strength with respect to prior art ball joints. [Means for solving the problem]

[0016] In accordance with an aspect of at least one embodiment of the present invention, the volume of the cage may be a volume having a constant cross-sectional area.

[0017] For this reason, the cage has continuity throughout its volumetric extent and therefore does not have any fracture zones such as notches or voids.

[0018] The advantage of such a volume with a constant cross-sectional area is that it provides a friction section between the cage and the balls without discontinuities.

[0019] Having several layers also makes it possible to avoid break lines that form at the junction between the two fabric edges of a single layer.

[0020] The thickness of the fabric forming these layers is selected to be relatively thin, thereby enhancing the mechanical strength of the self-lubricating composite.

[0021] Additionally, a cage that fits or is paired with a ball allows for controlled play between the ball and the cage.

[0022] In particular, this makes it possible to obtain a self-lubricating ball joint with potentially significantly reduced play between the ball and the cage with respect to prior art ball joints.

[0023] A cage adapted to the ball also makes it possible to prevent wear of the cage by the ball.

[0024] Furthermore, due to the use of composite materials, the corrosion resistance of the cage is increased with respect to the prior art, as such materials are less or not at all susceptible to corrosion.

[0025] The term ball is used here to denote a part whose shape corresponds to a spherical indentation, in other words a ball segment, i.e. the shape obtained after cutting the ball in two planes, which are here parallel. More specifically, here the shape of the spherical indentation is obtained after cutting the ball in two parallel planes symmetrical with respect to the center of the ball.

[0026] The cage has an inner surface that also has the shape of a spherical indentation, and its outer surface can have a shape corresponding to a spherical indentation obtained by cutting a sphere in two symmetrical parallel planes about the center of the ball, or a shape corresponding to a cylindrical surface.

[0027] According to some embodiments, it may be contemplated that the two planes are neither parallel nor symmetrical with respect to the center of the ball.

[0028] It is understood that by a volume having a constant cross-sectional area, the cage has continuity throughout the extent of the volume and therefore does not have any fracture zones such as notches or cavities.

[0029] According to an aspect of at least one embodiment of the present invention, the self-lubricating composite includes at least one strip having a thickness in the range of 20 μm to 200 μm.

[0030] This strip of self-lubricating composite is deposited to form the first laminate layer.

[0031] In this strip of self-lubricating composite, the fabric is impregnated with resin and then deposited to form the first laminate layer.

[0032] It should be noted that the resin may contain fillers.

[0033] For example, the resin may include a lubricating filler.

[0034] The use of relatively thin strips of self-lubricating composite allows for control of the amount of self-lubricating composite deposited in a given location on the surface of the cage, and therefore better control of the thickness of the first laminate at a given location.

[0035] For example, this may make it possible to obtain a cage with a first laminate that has material homogeneity due to the use of relatively thin strips.

[0036] Furthermore, excellent resistance to tangential friction forces can be obtained thanks to the cross-weaving of the layers of the self-lubricating composite.

[0037] For this reason, according to one aspect of at least one embodiment of the present invention, the first laminate comprises a spider web weave of strips of self-lubricating composite according to an angle in the range of 0° to 90°.

[0038] It should be noted that the fabric intended to be mixed with the resin may be made of taffeta, satin, twill, or canvas, but does not exclude other fabric constructions.

[0039] In accordance with an aspect of at least one embodiment of the present invention, the cage includes a reinforcing shell surrounding the first laminate.

[0040] This reinforcing shell serves as a protection for the cage by forming an external reinforcement and thus imparting additional mechanical strength that makes it possible to limit not only deformation but also thermal expansion of the cage during operation of the self-lubricating ball joint.

[0041] According to one aspect of at least one embodiment of the present invention, the reinforcing shell is formed from a second laminate consisting of several layers including at least one composite material including a composite comprising fibers and a resin impregnated into the fibers.

[0042] According to one aspect of at least one embodiment of the present invention, the complex comprises: - composites containing carbon fibres, - composites containing glass fibre, - composites containing Kevlar® fibers, - self-lubricating complex, - A mixture of the above materials is selected from.

[0043] The fibers may also be a component of a fabric, i.e., at least one composite material includes a composite including a fabric made up of a plurality of fibers and a resin impregnated into the plurality of fibers.

[0044] Furthermore, the resin may be selected from thermosetting or thermoplastic resins.

[0045] The thermosetting resin may be an epoxy, vinyl ester, polyester, phenolic, or polyimide resin.

[0046] The thermoplastic resin may be, for example, a polyamide (PA6), polyetherketoneketone (PEKK) or polyetheretherketone (PEEK) type resin.

[0047] According to one aspect of the invention, there can be a certain transition thickness between the first and second laminates, where the weaves of the first and second laminates alternate, which makes it possible to avoid an excessively sharp interface between the two laminates.

[0048] In accordance with an aspect of at least one embodiment of the present invention, the ball is constructed at least in part from a corrosion-resistant material.

[0049] Balls constructed at least in part from a corrosion resistant material help improve the corrosion resistance of the self-lubricating ball joint.

[0050] According to one aspect of at least one embodiment of the present invention, the anti-corrosion material of the ball comprises: - Corrosion-resistant metals, - corrosion-resistant alloys, - corrosion-resistant metals, - Corrosion-resistant alloys, - Materials treated by salt bath nitriding, - Composite materials The composition includes at least one material from

[0051] An alloy refers to a solid homogeneous mixture of a metal and one or more other substances, which may optionally be metals or non-metals.

[0052] Corrosion-resistant alloys and metals have a natural ability to resist corrosion. Corrosion-resistant treated metals and alloys do not have an adequate natural ability to resist corrosion and are therefore treated to improve their corrosion resistance.

[0053] The present invention also relates to the use of a composite material comprising a self-lubricating composite comprising a fabric and a resin impregnated into the fabric to form several layers of a first laminate of a self-lubricating ball joint cage.

[0054] The present invention, as well as the various advantages it offers, will be more readily understood with reference to the following description of illustrative and non-limiting embodiments and the accompanying drawings, in which: [Brief explanation of the drawings]

[0055] [Figure 1] FIG. 1 is a top perspective view of a self-lubricating ball joint according to one embodiment of the present invention. [Figure 2] FIG. 2 is a side perspective view of the self-lubricating ball joint according to the embodiment of FIG. 1. [Figure 3] 2 is another side perspective view of the self-lubricating ball joint according to the embodiment of FIG. 1. [Figure 4a] 2 is a schematic side view of the self-lubricating ball joint according to the embodiment of FIG. 1; [Figure 4b] 4b is a schematic perspective view of a self-lubricating ball joint according to the embodiment of FIG. 4a; FIG. [Figure 4c] 4b is a schematic front view of the self-lubricating ball joint according to the embodiment of FIG. 4a; FIG. [Figure 4d] 4b is a schematic cross-sectional side view of a self-lubricating ball joint according to the embodiment of FIG. 4a; [Figure 5a] 2 is a schematic front view of the ball according to the embodiment of FIG. 1. [Figure 5b] 5b is a schematic cross-sectional side view of a ball according to the embodiment of FIG. 5a. [Figure 5c] 5b is a schematic perspective view of a ball according to the embodiment of FIG. 5a; [Figure 6a] FIG. 2 is a schematic front view of a first laminate according to the embodiment of FIG. 1. [Figure 6b] 6b is a schematic cross-sectional side view of a first laminate according to the embodiment of FIG. 6a; [Figure 6c] 6b is a schematic perspective view of a first stack according to the embodiment of FIG. 6a; FIG. [Figure 7a] 2 is a schematic front view of the reinforcing shell according to the embodiment of FIG. 1; [Figure 7b] 7b is a schematic cross-sectional side view of a reinforcing shell according to the embodiment of FIG. 7a; [Figure 7c]7b is a schematic perspective view of a reinforcing shell of a cage according to the embodiment of FIG. 7a; DETAILED DESCRIPTION OF THE INVENTION

[0056] The general principle of the present invention is based on the implementation of a self-lubricating ball joint, which includes a cage and balls, and which has improved corrosion resistance with respect to the prior art due to the fact that the cage is little or not affected by corrosion. Furthermore, the principle of the present invention is also based on the implementation of a self-lubricating ball joint, which has a predetermined controlled play between the cage and the balls.

[0057] With reference to Figures 1 to 7c, one embodiment of a self-lubricating ball joint according to the present invention will now be described.

[0058] As illustrated in these figures, the self-lubricating ball joint 1 comprises a ball 2 and a cage 3. As can be seen, the ball 2 is rotatably mounted within the cage 3. According to the invention, the cage 3 is a single piece.

[0059] Furthermore, in this embodiment, the cage has a volume of constant cross-sectional area. The cross-section of the cage (30) can be seen, for example, in Figure 4d.

[0060] In other words, the cage is made from a single piece and does not have any fracture zones such as notches or voids.

[0061] It comprises a first laminate 31 made up of several layers of composite material.

[0062] The composite material includes a self-lubricating composite that includes a fabric and a resin impregnated into the fabric.

[0063] The invention is therefore based on the use of a composite material comprising a self-lubricating composite comprising a woven fabric and a resin impregnated into the woven fabric, for forming several layers of a first laminate.

[0064] An advantage of the use of composite materials for this application is that it has been found that the corrosion resistance of the self-lubricating ball joint is increased with respect to the prior art as such materials are less or not at all susceptible to corrosion.

[0065] Furthermore, such composite materials make it possible to obtain a self-lubricating ball joint with a significantly reduced controlled play between the ball and the cage, unlike prior art self-lubricating ball joints, due to the fact that the cage is adapted to the ball.

[0066] The term "woven fabric" as used herein refers to a surface made of a combination of multiple threads. This fabric, together with an impregnated resin, forms a strip of a self-lubricating composite. This self-lubricating composite combines a low coefficient of friction with the ability to maintain satisfactory friction and mechanical properties during operation of the self-lubricating ball joint.

[0067] The relative configuration of the constituent yarns of the fabric can be selected to form channels between the various yarns that can be filled with resin.

[0068] Among the regular weave constructions, it is possible to use twill 2 / 2 construction fabrics formed by interlacing pairs of weft threads with pairs of warp threads.

[0069] It is also possible to use fabrics of taffeta construction which have a relatively high resistance to maximum interweaving of warp and weft threads.

[0070] The fabric is, in this embodiment, a fabric made from polyester.

[0071] Strips of the self-lubricating composite are deposited to form the layers of the first laminate 31 .

[0072] The resin may be, for example, a thermosetting resin or a thermoplastic resin.

[0073] The thermosetting resin may be an epoxy, vinyl ester, polyester, phenolic, or polyimide resin.

[0074] In this embodiment, the self-lubricating composite is presented in the form of a strip having a thickness of 20 μm to 200 μm.

[0075] The resin used in this embodiment is an epoxy resin impregnated with lubricant particles.

[0076] Further, according to these embodiments, the self-lubricating composite is arranged such that the first laminate 31 comprises a spider web weave of strips of the self-lubricating composite according to an angle in the range of 0° to 90°.

[0077] In other words, several strips of the self-lubricating composite may be superimposed, with one strip making an angle with the successive strip ranging from 0 to 90°.

[0078] In the illustrated embodiment, the first laminate 31 comprises a spider web weave of strips of the self-lubricating composite according to an angle of greater than or equal to 5° and less than 90°.

[0079] As can be seen in the different figures, the cage 3 further comprises a reinforcing shell 30 surrounding the first laminate 31 .

[0080] In other words, the reinforcing shell forms an external reinforcement, also known as a sheath or armor, surrounding the first laminate 31. This reinforcing shell 30 is formed from a second laminate of several layers including at least one composite material, including a composite comprising fibers and a resin impregnated into the fibers.

[0081] In this embodiment, the complex comprises: - composites containing carbon fibres, - composites containing glass fibre, - composites containing Kevlar® fibers, - self-lubricating complex, - A mixture of the above materials is selected from.

[0082] It should be noted that the layer may comprise a composite material, including a composite including at least a fabric made up of a plurality of fibers and a resin impregnating the fibers that make up the fabric.

[0083] As for the resin, as in the case of the cage, it may be selected from, for example, thermosetting or thermoplastic resins.

[0084] The thermosetting resin may be an epoxy, vinyl ester, polyester, phenolic, or polyimide resin.

[0085] The purpose of this reinforcing shell is to protect the cage when the self-lubricating ball joint is subjected to stress in an operating system. In other words, since stress in a self-lubricating ball joint causes the cage and balls to heat up under operating conditions, the reinforcing shell provides additional mechanical strength, limiting the deformation of the cage as well as its thermal expansion during operation of the self-lubricating ball joint. The reinforcing shell limits deformation and expansion to control play between the cage and balls.

[0086] In this embodiment, the ball is constructed at least in part from a corrosion resistant material to provide a self-lubricating ball joint that is little or not susceptible to corrosion.

[0087] Constructing the ball at least partially from a corrosion resistant material helps to improve the corrosion resistance of the self-lubricating ball joint and thus improve the service life of the self-lubricating ball joint.

[0088] This corrosion-resistant material is - Corrosion-resistant metals, - corrosion-resistant alloys, - corrosion-resistant metals, - Corrosion-resistant alloys, - Materials treated by salt bath nitriding, or - Composite materials The composition includes at least one material from

[0089] For example, the corrosion-resistant alloy may be stainless steel.

[0090] Such self-lubricating ball joints, in which the balls are made from a corrosion-resistant material, may be manufactured using a manufacturing method that includes a step of corrosion-resistant treatment of the material that makes up the balls.

[0091] This processing step may include, for example, a salt bath nitriding step to improve the corrosion resistance capabilities of the material.

[0092] According to an alternative embodiment, the treatment step may include a carbonitriding step.

[0093] The manufacturing method may, according to certain embodiments, include a step of testing the resulting material for corrosion resistance.

[0094] The manufacturing method then includes assembling the ball and cage to form a self-lubricating ball joint. [Explanation of symbols]

[0095] 1. Self-lubricating ball joint 2 balls 3 cages 30 cage, reinforced shell 31 first laminate

Claims

1. A self-lubricating ball joint (1) comprising a ball (2) and a cage (3), The balls are rotatably mounted within the cage (3), The cage (3) is a one-piece molding and includes a first laminate (31) made of multiple layers of composite material; The self-lubricating ball joint (1) is characterized in that the composite material includes a self-lubricating composite including a woven fabric and a resin impregnated into the woven fabric.

2. 2. The self-lubricating ball joint (1) according to claim 1, characterized in that the self-lubricating composite comprises at least one strip having a thickness in the range of 20 μm to 200 μm.

3. 3. The self-lubricating ball joint (1) according to claim 1 or 2, characterized in that the first laminate (31) comprises a spider web weave of strips of a self-lubricating composite according to an angle in the range of 0° to 90°.

4. 4. The self-lubricating ball joint (1) according to any one of claims 1 to 3, characterized in that the cage (3) comprises a reinforcing shell (30) surrounding the first laminate (31).

5. 5. The self-lubricating ball joint (1) according to claim 4, characterized in that the reinforcing shell (30) is formed from a second laminate of layers including at least one composite material including a composite including fibers and a resin impregnated into the fibers.

6. The complex is - composites containing carbon fibres, - composites containing glass fibres, - composites containing Kevlar® fibers, - self-lubricating complex, - Mixtures of the above materials 6. Self-lubricating ball joint (1) according to claim 5, characterized in that it is selected from:

7. 7. Self-lubricating ball joint (1) according to any one of claims 1 to 6, characterized in that the ball (2) is at least partially made of anti-corrosion material.

8. The anticorrosion material of the ball (2) is - corrosion-resistant metals, - corrosion-resistant alloys, - metals with corrosion protection; - corrosion-protected alloys, - Materials treated by salt bath nitriding, and - Composite materials 8. Self-lubricating ball joint (1) according to claim 7, characterized in that it contains at least one material from the group consisting of:

9. Use of a composite material comprising a self-lubricating composite including a woven fabric and a resin impregnated into the woven fabric to form a plurality of layers of a first laminate of a self-lubricating ball joint cage.

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