GB2280000A

GB2280000A - Sealing device for constant velocity joints

Info

Publication number: GB2280000A
Application number: GB9414056A
Authority: GB
Inventors: Regner Paulo Nelson
Original assignee: ATH Ltda
Current assignee: ATH Ltda
Priority date: 1993-07-15
Filing date: 1994-07-12
Publication date: 1995-01-18
Anticipated expiration: 2014-07-12
Also published as: GB2280000B; FR2707711B1; FR2707711A1; BR9302920A; ES2113261A1; IT1271671B; ITMI941485A0; DE4424953A1; JPH07190082A; ITMI941485A1; ES2113261B1; GB9414056D0

Description

a SEALING DEVICE FOR CONSTANT VELOCITY JOINTS 2280000 This invention

relates to a sealing device for a constant velocity joint which has an outer race and torque transmitting shaft.

Sealing devices available for this purpose are not appropriate to compensate the axial displacement. Boot seals, usually made of elastomeric material, are assembled at one end to the CV Joint outer race or to a support connected to it, and the other end is usually directly connected to the torque transmitting shaft. The boot seal is simultaneously submitted to the CV Joint angular movements and to the relative axial movements which occur between the torque transmitting shaft and the CV Joint outer race.

Current sealing devices have a limitation regarding the axial displacement, since the boot seal deformation may not exceed a given limit, above which their useful life is seriously reduced, mainly when the available assembling area is small. Another inconvenience of the construction of known sealing devices is that due to the need for greater flexibility to compensate the CV Joint axial and angular movements, the axial and radial stiffness of the geometry of the boot seal is low. This results in undesired deformation, structural instability and even ruptures when submitted to high rotational speeds. Another problem of this type of sealing device is that it can accumulate lubricant coming from the CV Joint. The accumulated material may cause excessive deformation or even collapse of the boot seal, as a result of the centrifugal force acting on the lubricant under high speed rotations.

The purpose of this invention is to provide a sealing device for CV sliding joints which stays geometrically stable even under high speed rotations, lasts longer and allows high relative axial displacements between the CV Joint outer race and the torque transmitting shaft.

According to the the present invention a sealing device for a constant velocity joint which has an outer race and a torque transmitting shaft, comprises a boot seal, seal adapter, and a sleeve that can slide axially on the torque transmitting shaft, one end of the boot seal being assembled on said sliding sleeve and the outer end being connected to the seal adapter which is assembled on said outer race.

The first advantage of this invention is that the sealing device allows a large relative axial displacement between the race, since to the axial on the boot seal. between the torque transmitting shaft and the CV Joint outer race are absorbed by the sliding sleeve. Consequently, large axial displacements of the CV Joint can be obtained with small levels of strain on the boot seal.

torque transmitting shaft and the CV Joint outer the boot seal is connected through its outer end sliding hub, which prevents any severe strain The nossible relative axial displacements The second advantage of said invention is the boot seal geometry, which is designed to compensate for the CV Joint angular movements, working at lower levels of stress and strain which affords it higher duration and greater resistance to fatigue. This type of construction makes possible the use of a boot seal with greater axial and radial stiffness, ensuring a better structural stability even under high speed rotations.

The third advantage of the sealing device is that the seal adapter side surface can be tapered and inclined tothe direction of the outer race of the CV Joint. This ensures the return of any lubricant eventually deposited into the inner surface of the seal adapter back to the CV Joint, through the centrifugal force resulting from the rotation of the system.

An added fourth advantage is that the boot seal has on its outer end a venting hole which compensates for the differences of pressure between the inner and outer parts of the sealing device. This venting hole prevents the creation of differential pressure gradients that may cause undesired deformity or even the rupture of the boot seal.

The invention can be performed in many ways but two embodiments will now be described by way of example and with reference to the accompanying drawings in which:

Figure 1 is a longitudinal sectional side elevation of a device according to the invention; Figure 2 is a longitudinal sectional side elevation of a boot seal as shown in Figure 1; Figure 3 is a longitudinal sectional side elevation of a seal adapter as used in Figure 1; Figure 4 is a half longitudinal section of an alternative boot seal construction; Figure 5 is a half longitudinal section of an alternative seal adapter construction; and, Figure 6 is half longitudinal section of a preferred sliding sleeve construction.

Figure 1 shows a sealing device according to the invention assembled on a sliding CV Joint (1) and on a torque transmitting shaft (2), and which includes a boot seal (3), a seal adapter (4) and a sliding sleeve (5). The boot seal (3), made of elastomeric or polymeric material, is connected to the sleeve (5) which slides axially on the torque transmitting shaft surface, on which the inner race (11) of the CV Joint is assembled. At the other end, the boot seal (3) is connected to the seal adapter (4) which, in turn, is assembled on the outer race (12) of the CV Joint (1).

Referring to Figure 2, the boot seal (3) has a larger end (31) which is connected to the seal adapter (4), while the smaller end (32) is connected to the outer surface of the sliding sleeve (5). A venting hole (33) on the smaller end (32) acts as a pressure equalizer between the interior of the sealing device and atmosphere. The longitudinal section of the boot seal (3) side surface (34) has two inclined segments towards the torque transmitting shaft (2), joined by a concave curve which furnishes an axial and radial stiffness larger than the contemporary known seals, offering a greater dimensional stability under rotational motion.

As shown in Figure 3, the seal adapter (4) which can be metal is connected at one end to the outer race (12) of the CV Joint (1) through an encasement (41), the other end having a circumferential fold (42) which holds the larger end (31) of the boot seal, to provide a joined set. The seal adapter side surface (43) is tapered, increasing its diameter towards the Joint (1), which ensures that any lubricant coming from the Joint (1) or from the boot seal (3) will be returned to the Joint (1), through centrifugal f orce.

Figure 4 shows an alternative seal (3) construction with thermoplastic material which, due to its higher rigidity, allows a folded shape without harm to the geometric stability. In this construction the boot seal (31) has a larger end (311) assembled on the outer surface (4') of the seal adapter. The smaller end (32') is assembled on the outer surface of the sliding sleeve (5). The boot seal middle section has convolutions (341). Both ends, the larger one (31') as well as the smaller one (321) have a circumferential recess (331) in order to fix the boot seal in position. Since the boot seal (3') does not need to compensate for axial displacements, it can have a reduced length and a thicker wall, with axial and radial stiffness higher than known thermoplastic-made boot seals, thus having a higher dimensional stability under rotation.

Figure 5 shows an alternative form of seal adapter (4') used together with the boot seal (3') shown on Figure 4. This seal adapter (4') is assembled on the outer race (12), through the recess (41') and under the larger end (311) of the boot seal (3') through an annular groove (42'). This seal adapter (4') has no side surface.

Figure 6 shows a preferred form of the sliding sleeve (5) construction which can be made of metal and which has a shoulder (51) on its outer surface to position the boot seal (3 or 3'). The sleeve has a retainer (52) made of a plastics material to provide sealing between the sleeve and the torque transmitting shaft (2).

Claims

1. A sealing device for a constant velocity joint which has an outer race and a torque transmitting shaft, and comprising a boot seal, seal adapter, and a sleeve that can slide axially on the torque transmitting shaft, one end of the boot seal being assembled on said sliding sleeve and the other end being connected to the seal adapter which is assembled on said outer race.

2. A sealing device for a constant velocity joint as claimed in claim 1 in which an end of said boot seal is of larger diameter and is assembled on the seal adapter and the other end, of smaller diameter, is assembled on the outer surface of said sliding sleeve, the smaller end having a breathing channel which acts to equalise the internal and external pressures and the longitudinal cross-section of the boot seal side surface having two inclined segments towards the said torque transmitting shaft which are joined by a concave curve.

3. A sealing device for a constant velocity joint as claimed in claim 1 or claim 2 in which the seal adapter has an encasement for assembly to the said outer race of the constant velocity joint, a side surface and a circumferential fold to hold the adjacent end of the boot seal, said side surface being tapered and increasing in diameter towards the constant velocity joint.

4. A sealing device for a constant velocity joint as claimed in claim 1 in which one end of said boot seal is or larger diameter and is assembled on the outer end surface of the seal adapter and the other end of smaller diameter is assembled on the outer surface of said sliding sleeve, a mid section of said boot seal being convoluted, and being provided with a circumferential recess at each end.

5. A sealing device for a constant velocity joint as claimed in claim 1 or claim 4 in which the seal adapter has an encasement for assembly on said outer race of the constant velocity joint and a recess directly joined to said encasement to connect the adjacent end of the boot seal.

6. A sealing device for a constant velocity joint as claimed in any one of the preceding claims in which the axially sliding sleeve has a shoulder on its outer surface and a seal at one end.

7. A sealing device for a constant velocity joint substantially as described herein with reference to and as shown in Figures 1 to 3 and Figures 4 to 6 of the accompanying drawings.