Endless belt power transmission systems or components – Friction drive belt – Including plural interconnected members each having a drive...
Reexamination Certificate
1999-07-30
2001-05-29
Bucci, David A. (Department: 3682)
Endless belt power transmission systems or components
Friction drive belt
Including plural interconnected members each having a drive...
C474S242000, C474S240000, C474S201000
Reexamination Certificate
active
06238313
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a drive.
DESCRIPTION OF THE RELATED ART
Such a drive belt is known from the publication of U.S. Pat. No. 5,004,450. In the construction known from this publication, the height, i.e. the radial length of the contact faces of a transverse element is defined such, relative to the width of the element that a stable positioning between the sheaves of a pulley of the element is obtained, i.e. within a plane at right angles to the longitudinal direction of the belt.
From European patent publication EP-A-0626526, it is further known that, due to the so called misalignment phenomenon, elements of a belt adversely tend to enter a pulley at an angle relative to said pre-mentioned plane at a right angle to the longitudinal direction. This misalignment phenomenon, e.g. from U.S. Pat. No. 4,854,919, represents that the belt, at certain transmission ratios, is not at a right angle relative to the axis of rotation of a pulley. This geometrical characteristic may occur during operation of the belt in pulleys of which only one sheave is made axially moveable, as is practised in commercially produced transmissions. From said European document it is known to limit the possible rotation of the transverse elements through geometrically limiting the arc tangent between a specified transverse width within an element and the amount of radial play allowed to a carrier therefor. A disadvantage of this known construction is that in certain belt/pulley arrangements the elements still appear to enter a pulley adversely. Moreover, the known construction requires the projection and recess part, as usually applied in the head part of an element, to be shaped such that a recess may take up a projection with lateral play. Such a shape is difficult to produce.
SUMMARY OF THE INVENTION
It is the object of the invention to arrive at alternatively defined belt geometry, realising a properly and durably functioning belt with a majority of imaginable belt/pulley combinations as used in the automotive field. A belt of the invention is provided with such features is capable of operating correctly in combination with a large number of pulley sets having varying pulley centre distances within a range as practised in the automotive area. Particularly, the present solution provides that between one longitudinal end of a belt, i.e. when seen in plan view, and the other end of the other pulley of a set, all elements may remain running in a virtually straight line, i.e. without being bent off from its direction when entered in a pulley. This effect has been made possible by defining the claimed minimum and appropriate axial play of a carrier within a receiving slot of an element. By this construction, elements tend to be guided laterally between two pulleys, so that significantly the sensitively of a belt for misalignment is reduced. In particular the impact of an element on a sheave, when entering a pulley is minimised. Also the invention reduces the level of created noise in the transmission, as well as the loss of kinetic energy in the belt.
In utilising the carrier as a guiding element, i.e. by allowing contact between a carrier and an element neck, the present invention overcomes the technical prejudice in the field of continuously variable transmission technology, that contacts between a carrier side and a neck part should not be allowed because of risk of deterioration of the carrier through burring, and hence the risk of failure of a belt within a commercialised transmission. This prejudice is overcome by the acknowledgement of technical progress, in rounding and hardening the neck part and the belt sides, and by realising that an element within an arrangement according to the invention is only gradually moved axially during it's path between two pulleys, without large impact and without any force load of the element. Thus, the rise of adverse mutual contacting of carrier and element neck is minimal. Also, it is recognised that within one pulley to be exited by an element, the carrier will already move axially to compensate for misalignment, whereas the element is forced straight forward until it is released from the sheaves of a pulley. In constructions according to the invention, at leaving a pulley, the element neck and a belt side may virtually be contiguous, i.e. with minimal play, so that also the impact there between is kept minimal.
Additionally, the reduction in amount of play recognised by the invention provides an improved freedom of design, advantageously usable in reducing the width of the elements and therewith the weight of the belt, strengthening the neck part of an element or, increasing the width of a carrier within the same element. As to the latter possibility typically, with a belt according to the invention, having a width of 24 mm, a known play of e.g. 1.2 mm may be reduced to 0.2 mm. The width of a carrier may thereby e.g. being increased from 8.75 to 10.1 mm, totalling 20.2 mm of carrier within commonly practised belt types.
It is remarked that from the Patent abstracts of Japan publication NR. 08021488, in a belt type having two separate carriers, it is known per se to minimise clearance or play between a neck part and a carrier side. In the construction known from this document the minimised play is taught to be asymmetrically set to 0.7 mm for one carrier and to 1.3 mm to the other, totalling a play of 2 mm.
The present invention also points away from the construction known from the Japanese patent application No. 167896/1986, indicating that clearance between a so called pillar and the ring side edge should be above the value of misalignment.
REFERENCES:
patent: 4596536 (1986-06-01), Okawa et al.
patent: 4610648 (1986-09-01), Miranti, Jr.
patent: 4617007 (1986-10-01), Miranti, Jr. et al.
patent: 4826473 (1989-05-01), Miyawaki
patent: 4832671 (1989-05-01), Satoh
patent: 4854919 (1989-08-01), van Lith
patent: 4976663 (1990-12-01), Hendrikus
patent: 5004450 (1991-04-01), Ide
patent: 5439422 (1995-08-01), Smeets
patent: 0 626 526 (1994-11-01), None
patent: 167896 (1986-10-01), None
patent: 8-021488 (1996-01-01), None
Lith Johannes Hendrikus
Peters Wilhelmus Peter Catharina
Smeets Paulus Maria
Bucci David A.
Charles Marcus
Van Doorne's Transmissie B.V.
Young & Thompson
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