Joints and connections – Flexible diaphragm or bellows
Reexamination Certificate
1998-07-17
2001-05-08
Browne, Lynne H. (Department: 3629)
Joints and connections
Flexible diaphragm or bellows
C464S175000, C277S636000, C277S634000
Reexamination Certificate
active
06227748
ABSTRACT:
TECHNICAL FIELD
This invention relates to protective gaiters for joints particularly although not exclusively for use in motor vehicles.
BACKGROUND ART
Flexible rubber gaiters are used in motor cars to protect constant velocity joints so as to prevent ingress of dirt and moisture and egress of lubricants. These gaiters customarily comprise moulded tubes having cylindrical end portions suitably diametered to fit the pertaining joint members and a flexible convoluted central portion. The end portions are clamped to the joint members by straps located in seating channels in the rubber gaiter.
UK Patent No. 2156452 discloses a moulded rubber gaiter of this kind further having end portions adapted by the provision of multiple fitting sections of different diameters allowing attachment to a number of different dimensions of joint members. This provides a versatile ‘universal’ gaiter which can be used with constant velocity joints of different motor car models by appropriate cutting away of unwanted outer zones of the fitting sections. The requisite flexibility of the gaiter is derived essentially from the central portion which may be a bellows type construction and the end portions are of limited flexibility. Whilst this arrangement is generally satisfactory, in the case where the gaiter is used with an appreciable number of remaining inner ones of the fitting sections, these remaining fitting sections impose limitations on the overall flexibility of the gaiter because the fitting sections incorporate relatively rigid seating channels for the fixing straps. This is especially problematical at the wider diameter end of the gaiter where, in use, there is considerable axial flexing as the joint members rotate and pivot relative to each other (as is the case with constant velocity joints).
With the aim of improving flexibility at the wider end portion, GB 2232729 proposes inwardly curved fitting sections with outwardly curved folds between these sections. With this arrangement, the flexibility of the wider end portion of the gaiter is enhanced by the outwardly curved folds and also by the unused curved fitting sections which act as further folds.
This arrangement has considerable advantages. However, the provision of curved folds between the fitting sections adds to the length and bulk of the gaiter thereby requiring an increased amount of material. Also, the use of flexible inner and outer curved folds at the wider end of the gaiter can give rise to collapsing of the fold structure and consequent restriction of flexibility and increased wear.
In the latter respect, where the movement of the gaiter in use involves rotation about its axis and also pivoting or flexing at a position along the axis at the wider end of the gaiter, this has the effect of bending the folds at the wider end of the gaiter at one side, in the manner of a hinge joint and this can cause collapse of the folds rather than smooth pivoting. The folds thereby become flattened or crumpled.
DISCLOSURE OF THE INVENTION
An object of the present invention is to enhance further the flexibility of the wider end portion.
According to the invention therefore there is provided a protective gaiter to fit around a lubricated joint between joint members, said gaiter comprising a generally frusto-conical flexible tubular body having first and second end portions with inner and outer surfaces thereto and a central portion between said end portions, said first end portion being wider than said second end portion and having axially spaced annular fitting sections incorporating annular seating areas around said outer surface thereof to receive a fixing device whereby the said inner surface thereof can be clamped into sealing engagement respectively with the respective said joint member, said central portion having main folds therein so as to permit axial extension of the body, said fitting sections of said wider end portion being defined by stepped configurations, and said wider end portion having flexible portions between the seating areas, characterised in that said flexible portions extend inwardly relative to said seating areas towards the axis of the gaiter to facilitate axial flexing of the gaiter at said wider end portion.
With this arrangement, flexing can take place at the wider end portion in the manner of a hinge in the vicinity of the flexible portions between adjacent seating areas. Each seating area can act as a lever pivoting at its junction with the adjacent flexible portion. Due to this mode of flexing the axial dimensions of the wider end portion of the gaiter can be kept to a minimum: it is not necessary to have a relatively long structure, such as a long curved intermediate fold, to ensure adequate flexibility. Also, in so far as flexing occurs at hinge joints at the flexible portions, there is less likelihood of collapsing occurring than in the case where flexing is required to take place essentially around a fold. It is therefore possible to maintain good flexing performance of the gaiter whether used with all fitting sections intact, or with one or more fitting sections cut away.
In accordance with one embodiment, the seating areas are at least generally axially parallel and the inwardly directed flexible portions comprise secondary folds. Due to the hinge flexing mentioned above, these folds can be of small axial dimensions.
Alternatively and preferably however, the seating areas are inclined inwardly and the flexible portions are defined by transitions between the inner end of each such area and the next adjacent fitting section.
With the latter embodiment the stepped configurations defining the annular fitting sections at the wider end portion of the gaiter may be generally Z-shaped. It is thereby possible to avoid or minimise the use of axially parallel portions of the gaiter at the wider end portion which facilitates pivoting of the gaiter without requiring incorporation of structures which appreciably increase its length. Ingeniously, the use of inclined structures permits incorporation of extra material and extra flexibility without adverse effect on other properties.
The transition between each inwardly directed seating area and the adjacent fitting section may be effected via generally radially extending walls preferably joint at acute angles to the fitting sections. These walls may be at least generally flat, as also may be the fitting sections.
Most preferably the seating areas are inclined inwardly in a direction towards the wider end portion of the gaiter.
As an alternative to the above mentioned radial walls and angular junctions, if desired the flexible portions may be defined by folds with curved transitions. These folds may be substantially J-shaped and each limb may be curved.
In the case of the above mentioned first embodiment employing secondary folds, these folds may be angular or curved in like manner to the flexible portions described in the immediately preceding paragraph.
With regard to the seating areas, these may comprise distinct channels. Alternatively, they may simply comprise surface areas, preferably flat areas with projecting structures adjoining or bounding the areas for location purposes, and which may be of greater width than the fixing device whereby such projecting structures act to facilitate location without making a close fit with the device.
With regard to the said first embodiment, the transition between the intermediate secondary folds and each seating area may be such that the seating area is substantially in the form of the top part of a fold: that is, on each side of the seating area there is a curved transition part of the adjacent intermediate secondary fold.
In a particularly preferred version of the first embodiment, each seating area is a flat or substantially flat structure and this may have a thinner wall thickness than the adjacent secondary folds in order to compensate for the reduction in flexibility arising from its flat conformation.
In order to enhance the lever and hinge joint effect described above, there may be an upwardly curved transition fold betwee
Bidle Simon
Hayward Phillip Fields
Bochna David E.
Browne Lynne H.
Hayward Phillip Fields
Pearson & Pearson LLP
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