Joints and connections – Interfitted members – Clamped members
Reexamination Certificate
2001-11-28
2004-09-07
Knight, Anthony (Department: 3679)
Joints and connections
Interfitted members
Clamped members
C403S326000, C403S329000, C403S365000, C403S367000, C403S373000, C015S250310, C015S250340
Reexamination Certificate
active
06786671
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a windshield wiper arm fixing device, in particular for windshields of automotive vehicles.
The importance of reliable and correct fixing of such equipment to the performance of the windshield wipers and therefore to safe driving of the vehicle in rainy or snowy weather is well known. In the devices most widely used at present, the ends of the oscillating spindles to which the windshield wiper arms are fixed have a screwthreaded part onto which is screwed a nut for locking the arm, the screwthreaded part, which is of smaller diameter than the oscillating spindle, being joined to the latter by a generally frustoconical bearing surface with regular splines along the generatrices of the frustum of the cone.
Existing arms have a corresponding frustoconical mounting hole which, when first fitted, is forced over the splined part of the spindle, whose splines are then imprinted into the bore of the arm, which is generally made of a metal softer than the steel of the spindle, such as a zinc-based alloy known as Zamak or an aluminum-based alloy.
The imprinting of the splines in the bore prevents the shaft rotating relative to the spindle. However, this type of assembly, although simple and inexpensive, is not very resistant to demounting and does not guarantee that the arm is perpendicular to its rotation axis, in particular where it is nested over the splined frustoconical part.
If an adjustment in its position proves necessary, clamping it again in a different angular position on the surface of the bore of the arm, which already has splines imprinted in it, will take place on top of the original splines, causing them to be chewed up, and the splines will no longer be able to transmit the drive torque for the windshield wiper arm. For this reason, automotive vehicle manufacturers scrap any windshield wiper arm that is mounted incorrectly, either on the production line or as a repair, and replace it with a new one in order to guarantee mechanical strength and to avoid a reduced locking effect and risks of deformation on the clamping surfaces that can lead to defective positioning of the arm. The quality of the assembly will depend on the care with which the arm was initially positioned on the production line.
This type of mounting on a splined frustoconical bearing surface does not accurately control the axial hi position of the arm on the spindle because, although the nature of the materials used enables the male splines on the steel spindle to be impressed into the female cone of the frustoconical bearing surface, the frustoconical shape adopted makes it difficult to maintain the assembly tension (the materials used, which are generally soft metals, having a tendency to creep), degrading the quality of the connection, and the shaft then turns within the female frustoconical bearing surface without driving the windshield wiper.
On the other hand, if the frustoconical assembly is well designed and functions correctly, it is inherently self-wedging and an extractor is required to demount it.
Moreover, with a frustoconical bearing surface, especially a short one, it is difficult to guarantee that the arm is perpendicular to its spindle. Any such defect of perpendicularity leads to malfunctions and in particular to serious variations in the intended wiping speed and to noise and vibration of the rubber windshield wiper blade.
Pressed sheet metal arm drivers give rise to other problems. Being made of steel, the marking of the frustoconical bearing surface of the driver by the splines on the spindle will be very superficial, because of the hardness of the material and the particularly small height of the bearing surface, and this will necessitate significantly increasing the assembly pressures
SUMMARY OF THE INVENTION
The subject matter of the present invention is a windshield wiper arm structure which enables precise adjustment of its angular position, combined with low cost, and which can be mounted quickly, in a single operation, with easy adjustment of the angular location of the windshield wiper arm.
According to the invention, a device for fixing a windshield wiper arm hub to the spindle with locking means for locking the arm to the spindle, a cavity formed in the hub containing means for adjusting the angular position of the arm relative to the spindle, said hub bearing on an abutment base nested over a bearing surface of the spindle, is characterized in that, the locking means being adapted to assume either a clamping position or an unclamping position, said adjustment means include a connecting ring constrained to rotate with the spindle and accommodated in said cavity of the hub with some play allowing limited relative angular movement between the connecting ring and the hub in the unclamping position of the locking means, whereas all relative movement between the connecting ring and the hub is prohibited in the clamping position of the locking means.
Advantageously, said angular play of the connecting ring inside the cavity of the hub is determined by nesting of the connecting ring along a polygonal contour.
Accordingly, the contour of the connecting ring can be integrated with the shaft to nest it directly in the complementary cavity of the hub, and the same spring means can be disposed between the shaft and the hub, which eliminates the use of a connecting ring without excessively complicating the shape of the end of the arm. A bearing surface of polygonal shape, for example hexagonal shape, will be formed directly on the shaft, that bearing surface being nested inside a corresponding cavity of the hub having the same, but slightly larger, shape to enable angular play of the arm on the shaft.
Preferably, an angular movement buffering spring member is disposed in a space between the inside of the hub and the outside of the connecting ring.
In this variant, to damp end of sweep impacts on each reversal of the direction of operation, there is provided in the space directly separating the shaft from the hub a buffer member such as a leaf spring of appropriate shape that will equally make it possible to retain the arm in its theoretical adjustment position relative to the shaft.
Advantageously, the connecting ring has a cylindrical outside contour nested inside a corresponding bore of the hub, its rotation in said bore being angularly limited by at least one radial rib able to oscillate in at least one corresponding radial housing of the hub, spring means being disposed between the radial walls of the rib and the facing radial walls of the radial housing.
In a preferred embodiment the connecting ring will have a cylindrical outside contour nested inside a corresponding bore of the hub, its rotation in that bore being angularly limited by at least one radial rib able to oscillate in a corresponding, slightly wider groove in the hub, a larger radial rib being disposed in a larger cavity of the hub, for example in the portion thereof extending along the axis of the arm, bearing buffering spring means being disposed between the radial walls of the rib and the facing radial walls of the cavity. These spring means also determine the theoretical angular location on first fitting and retain the ring, thus facilitating fitting the arm to the shaft in its theoretical centered position and holding it in position during assembly.
There will then be provided a controlled range of adjustment of the angular position of the arm, in elastic bearing engagement. Once fitted, the arm will be locked by tightening the assembly nut with the locking washer, as previously.
Preferably, a metal outer shell forms a housing around the hub.
The arm according to the invention has an end for assembly onto the spindle consisting of a composite structure characterized by an external shell, preferably of pressed sheet metal, forming a drive housing of the windshield wiper arm, which housing is open at the bottom, has a hole at the top through which the spindle passes, and receives means for locking the arm onto the spindle such as a nut with a locking wash
Ferguson Michael P.
Knight Anthony
Societe de Recherches d'Etudes et de Valorisation
Young & Thompson
LandOfFree
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