Machine element or mechanism – Gearing – Nonplanetary gearing differential type
Patent
1997-04-11
1999-08-10
Bonck, Rodney H.
Machine element or mechanism
Gearing
Nonplanetary gearing differential type
74 66, F16H 4812
Patent
active
059341580
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to differential drive mechanisms, particularly automotive differentials of limited slip type, and is concerned with that type of differential drive mechanism which comprises a cage, which is rotatable about an axis and represents the input, two coaxial output shafts which are rotatable with respect to the cage about the said axis, a coupling which is connected eccentrically to the two output shafts to transmit relative contra-rotational movement between them by connections which permit relative rotation of the coupling and the output shafts about an axis substantially parallel to the said axis and a restraint member which is coupled to the cage and to the coupling such that the coupling is rotatable with respect to the cage about an axis substantially perpendicular to the said axis and capable of reciprocating movement in a direction perpendicular to the said axis but prevented from movement in a direction parallel to the said axis, the eccentric connection of the coupling and the output shafts including a respective eccentric hole in the inner end of each output shaft in which the associated end of the coupling is received, the ends of the coupling having a part-spherical engagement surface, a slipper which affords a complementary part-spherical internal surface being received in each eccentric hole and each engagement surface being in engagement with a respective complementary internal surface. Such a drive mechanism is disclosed in EP-A-0611166.
The provision of these slippers is very important because if they were not present the part-spherical engagement surface at the ends of the coupling would directly engage the surface of the associated eccentric hole whereby the contact between these two surfaces would necessarily be a point contact. In use, the force transmitted between the coupling member and the inner ends of the output shafts is very substantial indeed, and if this were transmitted through a point contact it would produce very substantial contact loads. When the differential is differentiating, that is to say when the two output shafts rotate relative to one another, this would rapidly lead to abrasion and destruction of the ends of the coupling and the surface of the eccentric holes.
DESCRIPTION OF THE PRIOR ART
In EP-A-0611166, the eccentric holes and the external shape of the sleeves are of circular section whereby the loads are transmitted between the sleeves and the inner ends of the output shafts over a line contact rather than a point contact which results in a substantial reduction in the contact pressures and thus in the abrasion of the contacting surfaces.
When the differential of EP-A-0611166 differentiates, the output shafts rotate with respect to the coupling. This rotational movement will occur between the sleeves and the surfaces of the eccentric holes or between the sleeves and the ends of the coupling or, more probably, a combination of the two. During differentiation, the coupling reciprocates or oscillates both linearly in the direction of the length of the restraint member and rotationally about the length of the restraint member. The amplitude of the rotational oscillation will depend on the dimensions of the various components but is typically 36.degree.. Thus in the two extreme positions, the longitudinal axis of the coupling may be inclined at, say, 18.degree.to the longitudinal axis of the output shafts.
Due to the necessity of making the differential and its components as strong and as compact as possible this introduces the risk of the coupling member fouling, that is to say coming into engagement with, the edge of the slipper and perhaps also the edge of the eccentric hole.
This potential problem is overcome in EP-A-0611166 by cutting away the surface of the coupling, that is to say providing the coupling with a neck, directly inboard of the part-spherical engagement surfaces. Whilst this overcomes the potential problem, it does result in a structural weakening of the most highly stressed component of th
REFERENCES:
patent: 628135 (1899-07-01), Williams
patent: 1098423 (1914-06-01), Bayly
patent: 1561150 (1925-11-01), Gerber
patent: 4291591 (1981-09-01), Ross
patent: 5435210 (1995-07-01), Moore et al.
patent: 5495779 (1996-03-01), Harr
Axial Wave Drive BV
Bonck Rodney H.
Lund Scott
Ricardo Consulting Engineers Limited
LandOfFree
Differential drive mechanisms does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Differential drive mechanisms, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Differential drive mechanisms will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1108831