Lubricated universal joint correcting angular and axial misalignments

Abstract

The invention relates to a universal joint (1) comprising two articulation forks (10, 20), each extending along a respective elongation direction (O1, O2), and each comprising two facing plates (12, 22). The forks are articulated to each other at their facings by a cross joint (30) comprising a first journal (31) and a second journal (32) arranged in the form of a cross perpendicular to each other. The two free ends of each journal are engaged in two corresponding oblong holes (12A, 22A) arranged opposite each other on the two facing plates of a respective fork and oriented parallel to the elongation direction of that fork. The universal joint further comprises an elastically deformable bellows (40) filled with a lubricant and in which are enclosed in a sealed manner the said cross member and the cheeks of the said articulation forks.Figure to be published with the abbreviation: Fig. 2.

Description

Title of the invention: Lubricated universal joint correcting angular and axial misalignments technical field

[0001] The technical context of the present invention is that of rotating coupling elements, and in particular those used in the automotive field, without limitation. More specifically, the invention relates to a universal joint. Previous technique

[0002] Devices for transmitting motion between two mechanical shafts that are not perfectly aligned are essential in many industrial and mechanical applications. Among these devices, the cardan joint, also known as a universal joint, is mainly used to correct angular misalignments between two rotating shafts whose angular position relative to each other may change.

[0003] This type of joint allows uniform rotation, even when the shafts are not perfectly aligned, by transmitting the torque through a series of articulated movements.

[0004] In rear-wheel drive vehicles, the rear axle is driven by the rotational movement of the drive shaft, which transfers power from the drive motor located at the front. Universal joints are conventionally installed on the rear drivetrain of these vehicles between the drive motor's transmission shaft and the rear wheel shafts to correct angular misalignments between these rotating shafts.

[0005] When the rear axle of such a rear-wheel-drive vehicle is equipped with leaf springs, it does not move strictly along the vertical axis. Indeed, depending on the road geometry and the speed of the motor vehicle, the leaf spring compresses, causing the shackles to pivot and resulting in a slight variation in the wheelbase relative to the position of the rear wheels.

[0006] To compensate for these wheelbase variations and ensure continuous transmission, sliding joints are generally installed in series with the cardan joints, which generates additional costs, equipment and labor, as well as increased problems of reliability, wear and maintenance. Description of the invention

[0007] The present invention aims to improve the situation.

[0008] To this end, it proposes a universal joint comprising two articulation forks, each extending in a respective direction of elongation and each comprising two cheeks arranged opposite each other, said forks being articulated to each other at the level of their cheeks by a cross comprising a first trunnion and a second trunnion arranged in the form of a cross perpendicular to each other, the two free ends of each said trunnion being engaged in two corresponding holes made opposite each other on the two cheeks of a said respective articulation fork; characterized in that said holes provided on each said articulation fork are oblong and oriented parallel to said direction of elongation of said fork, and that said cardan joint further comprises an elastically deformable bellows filled with a lubricating product and in which said cross member and the cheeks of said articulation forks are hermetically sealed.

[0009] The universal joint according to the invention thus makes it possible to compensate for angular misalignment as well as axial variation in the wheelbase between two shafts coupled to its two pivot forks. Furthermore, keeping the cross member and the cheeks of the pivot forks permanently immersed in a lubricant minimizes the frictional forces they experience, thereby limiting their wear and increasing the lifespan of the universal joint.

[0010] According to preferred characteristics of said universal joint according to the invention: - said bellows is made of elastomer material; - said bellows comprises a corrugated cylindrical tubular main body surrounding said forks and exhibiting accordion-like undulations; - each articulation fork comprises a hollow cylindrical sleeve, intended to be coupled by fitting to a rotating shaft, and from an end edge of which its two cheeks protrude; - said bellows also includes two annular end collars connected to the two edges of said tubular body and each fitted in a watertight manner onto the sleeve of a corresponding said fork; - said lubricant product consists of a mineral, semi-synthetic or synthetic type lubricating oil; - said lubricant product consists of a synthetic lubricating oil based on polyglycol; and / or - said oblong holes made on said articulation forks all have the same length.

[0011] The invention also relates in a second aspect to a transmission system for motor vehicles comprising at least one such cardan joint.

[0012] The invention finally relates, in a third aspect, to a motor vehicle equipped with such a transmission system. Brief description of the drawings

[0013] The description of the invention will now be continued by a detailed description of an exemplary embodiment, given below by way of illustration but not limitation, with reference to the accompanying drawings, on which: - [Fig.1] represents a side elevation view of a cardan joint according to the invention; - [Fig.2] is a perspective view of the cardan joint of [Fig.1] part of the bellows of which has been cut out to allow a partial view of the constituent elements of this cardan concealed by this bellows; - [Fig.3] represents a perspective view of the universal joint of [Fig.1] without its bellows and in an angular misalignment configuration; and - [Fig.4] illustrates three top views of the cardan joint of [Fig.1] without its bellows and following three different axial adjustment configurations. Description of the implementation methods

[0014] With reference to figures 1 to 4, the cardan joint 1 according to the invention comprises a first articulation fork 10 and a second articulation fork 20 each extending in a respective elongation direction Ob O2.

[0015] Each of these articulation forks 10, 20 includes a hollow cylindrical sleeve 11, 21 intended to be coupled by fitting to a respective rotating shaft (for example, to the drive shaft of the drive motor of a vehicle for the sleeve 11 of the first fork 10 and to the shaft of a rear wheel of this vehicle for the sleeve of the second bushing 20).

[0016] Each articulation fork 10, 20 also includes two cheeks 12, 22 projecting out from an end edge of the sleeve 11,21 and arranged opposite each other symmetrically with respect to a median plane of this fork corresponding to a diametrical plane of its sleeve 11,21.

[0017] These two articulation forks 10, 20 are articulated with each other, at the level of their cheeks 12, 22, by a cross 30 comprising a first cylindrical trunnion 31 and a second cylindrical trunnion 32 arranged in the form of a cross perpendicular to each other.

[0018] The two free ends of each trunnion 31, 32 are engaged in two corresponding oblong holes 12A, 22A arranged opposite each other on the two cheeks 12, 22 of a respective articulation fork 10, 20 and oriented parallel to the elongation direction Oi, O2 of this fork.

[0019] This particular configuration of the holes 12A, 22A allows, on the one hand, the pivoting of each of the articulation forks 10, 20 around the axis of a corresponding trunnion 31, 32, and on the other hand, the relative translation between the cross member 30 and each articulation fork 10, 20 following the elongation direction Ob O2 of the latter.

[0020] The oblong holes 12A, 22A provided on the two articulation forks 10, 20 advantageously all have the same length so that the translational travel of each articulation fork 10, 20 vis-à-vis the cross 30 is identical.

[0021] The width dimension of these oblong holes 12A, 22A will preferably be chosen equal (or almost) to the diameter of the free ends of the trunnions 31, 32 so as to avoid any translational play between the articulation forks 10, 20 and the cross 30 along axes perpendicular to their directions of elongation Oi, O2.

[0022] Fig. 3 illustrates a perspective view of the cardan joint 1 according to the invention in an angular compensation configuration, in which it allows the smooth transmission of rotary motion between two shafts not shown coupled to the two articulation forks 10, 20 and angularly misaligned with respect to each other.

[0023] The angular compensation provided by the cardan joint 1 compensates for these angular misalignments and ensures the smooth transmission of rotary motion between these shafts while reducing the stresses and wear associated with these misalignments.

[0024] Fig. 4 illustrates several views A1, A2, A3 illustrating several different axial configurations.

[0025] In view A1, the cardan joint 1 occupies its maximum axial adjustment configuration away from the two forks 10, 20, in which the two free ends of the first trunnion 31 are abutted against the distal ends of the two corresponding oblong holes 12A of the first fork 10, while the two free ends of the second trunnion 32 are abutted against the distal ends of the two corresponding oblong holes 22A of the second fork 20.

[0026] In view A3, the cardan joint 1 occupies its maximum axial adjustment configuration in approach of the two forks 10, 20, in which the two free ends of the first trunnion 31 are abutted against the proximal ends of the two corresponding oblong holes 12A of the first fork 10, while the two free ends of the second trunnion 32 are abutted against the proximal ends of the two corresponding oblong holes 22A of the second fork 20.

[0027] View A2 shows the cardan joint 1 in an intermediate configuration between those illustrated by views A1 and A2, in which the two free ends of the first journal 31 are positioned at the center of the two corresponding oblong holes 12A of the first fork 10, while the two free ends of the second journal 32 are positioned at the center of the two corresponding oblong holes 22A of the second fork 20.

[0028] Thus, the cardan joint 1 according to the invention makes it possible to compensate for both an angular misalignment and an axial variation of the wheelbase between two shafts not shown coupled to the two articulation forks 10, 20.

[0029] The cardan joint 1 according to the invention further comprises an elastically deformable bellows 40 filled with a lubricating product and in which the cross 30 and the cheeks 12, 22 of the articulation forks 10, 20 are hermetically sealed.

[0030] Maintaining these elements permanently in such a lubricating product thus minimizes the frictional forces they undergo, thereby limiting their wear and increasing the lifespan of the cardan joint 1. This also optimizes the transmission efficiency of rotational energy between the two shafts coupled to the forks 10, 20 of this cardan joint 1.

[0031] The lubricant used will preferably consist of a lubricating oil.

[0032] For example, a mineral oil (i.e. derived from the refining of crude oil) may be used because of their availability, their relatively low cost, and their chemical stability properties.

[0033] For improved performance, a semi-synthetic or synthetic oil may also be used, particularly a synthetic polyglycol-based oil offering exceptional chemical and thermal stability. The use of a high-performance grease is also possible.

[0034] Thanks to its elasticity, the bellows 40 is able to follow the pivoting and translation of the forks 10, 20 with respect to this cross 30. This bellows 40 is advantageously made of an elastomeric material, preferably a thermoplastic elastomeric (TPE) such as a nitrile rubber, a polychloroprene or an EPDM (ethylene-propylene-diene monomer).

[0035] As can be seen in figures 1 and 2, the bellows 40 comprises a corrugated cylindrical tubular main body 41 surrounding the forks 10, 20 and having accordion-like undulations to facilitate its harmonious deformation by bending or by elongation or compression, during the pivoting and / or translation of the forks 10, 20. It also comprises two annular end collars 42 connected to the two edges of this tubular body 41 and each fitted in a sealed manner onto the sleeve 11, 21 of a corresponding fork 10, 20.

[0036] The main tubular body 41 of this bellows 40 is provided with an orifice 43 (partially visible in [Fig. 2]) for the injection of the lubricant. This orifice 43 is designed to be closed by a removable plug (not shown).

[0037] Numerous variations are conceivable, and it should be noted in this regard that the present invention is not limited to the embodiments described and illustrated, but It also encompasses all execution variants within the reach of a person skilled in the art. Furthermore, its implementation is not limited to the automotive sector.

Claims

Demands

1. Cardan joint (1) comprising two articulation forks (10, 20) each extending in a respective elongation direction (O1, O2) and each comprising two cheeks (12, 22) arranged opposite each other, said forks (10, 20) being articulated to each other at the level of their cheeks (12, 22) by a cross (30) comprising a first trunnion (31) and a second trunnion (32) arranged in the form of a cross perpendicular to each other, the two free ends of each said trunnion (31, 32) being engaged in two corresponding holes (12A, 22A) arranged opposite each other on the two cheeks (12, 22) of a respective articulation fork (10, 20);characterized in that said holes (12A, 22A) provided on each said articulation fork (10, 20) are oblong and oriented parallel to said elongation direction (Ob O2) of said fork (10, 20), and that said universal joint (1) further comprises an elastically deformable bellows (40) filled with a lubricant and in which said cross member (30) and the cheeks (12, 22) of said articulation forks (10, 20) are hermetically sealed.;

2. Cardan joint (1) according to claim 1, characterized in that said bellows is made of elastomeric material.

3. Cardan joint (1) according to any one of claims 1 or 2, characterized in that said bellows comprises a corrugated cylindrical tubular main body surrounding said forks and having accordion-like undulations.

4. Cardan joint (1) according to any one of claims 1 to 3, characterized in that each articulation fork (10, 20) comprises a hollow cylindrical sleeve (11, 21), intended to be coupled by fitting to a rotating shaft, and from an end edge of which its two cheeks (12, 22) project outwards.

5. Cardan joint (1) according to claims 3 and 4, characterized in that said bellows (40) also comprises two annular end collars (42) connected to the two edges of said tubular body (41) and each fitted in a sealed manner onto the sleeve (11, 21) of a corresponding fork (10, 20).

6. Cardan joint (1) according to any one of claims 1 to 5, characterized in that said lubricant product consists of a mineral, semi-synthetic or synthetic type lubricating oil.

7. Cardan joint (1) according to claim 6, characterized in that said lubricant product consists of a synthetic lubricating oil based on polyglycol.

8. Cardan joint (1) according to any one of claims 1 to 7, characterized in that said oblong holes (12A, 22A) provided on said articulation forks (10, 20) all have the same length.

9. Transmission system for motor vehicles, comprising at least one universal joint (1) according to any one of claims 1 to 8.

10. Motor vehicle equipped with a transmission system according to claim 9.

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