Friction gear transmission systems or components – Stepless ratio change – Driving and driven gears on nonlinear angularly related axes
Patent
1996-05-01
1998-03-24
Herrmann, Allan D.
Friction gear transmission systems or components
Stepless ratio change
Driving and driven gears on nonlinear angularly related axes
F16H 1544
Patent
active
057306818
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a variable-speed drive, particularly for vehicles.
BACKGROUND ART
According to German Patent n. 902 204, a variable-speed drive is formed comprising a central conical roller rotating about a respective axis and defined by a convex surface, and a number of outer conical rollers tangent to, opposed in relation to, and arranged in a ring about the central roller, and defined by respective concave lateral surfaces. The outer conical rollers rock in relation to the central roller to vary the velocity ratio of the drive by means of a control ring surrounding the outer conical rollers, movable along said axis, and presenting an inner surface mating in sliding manner with the lateral surfaces of the outer rollers.
Known variable-speed drives of the above type present several drawbacks, all due to the fact that, by virtue of the control ring mating in sliding manner with the outer rollers, a clutch is required for disconnecting the drive from the load prior to varying the velocity ratio, and for reconnecting the drive to the load once the velocity ratio is varied.
The above problem is solved, for example, by the variable-speed drive described and illustrated in Patent Application WO-A-93/05318 filed on 12 Aug., 1992, by the present Applicant, and wherein the control ring is replaced by a ring of balls also movable along the axis of the inner roller and interposed between the lateral surfaces of the outer rollers and a reaction element defined by a sleeve coaxial with and movable both ways along the axis of the inner roller.
Variable-speed drives of the above type, however, are relatively cumbersome due to the presence of said sleeve which, among other things, being movable, must be housed inside a protective casing.
Such drawbacks may be solved by replacing the sleeve with a number of reaction assemblies, one for each said ball, presenting respective rolling bodies cooperating with the respective balls, and supported by a single ring movable axially along said axis.
Though satisfactorily solving the size problem of the drive, such a design is relatively complex and expensive to produce due to the numerous-parts involved.
DISCLOSURE OF INVENTION
It is an object of the present invention to provide a variable-speed drive designed to overcome the aforementioned drawbacks and which, at the same time, is both straightforward and economical to produce and provides for a high degree of reliability.
According to the present invention, there is provided a variable-speed drive, particularly for vehicles, as defined in claim 1.
BRIEF DESCRIPTION OF THE DRAWINGS
A non-limiting embodiment of the present invention will be described by way of example with reference to the accompanying drawings, in which:
FIG. 1 shows a section of a preferred embodiment of the variable-speed drive according to the present invention;
FIG. 2 shows a larger-scale section of a detail in FIG. 1;
FIG. 3 shows an exploded view in perspective of a detail in FIG. 2.
BEST MODE FOR CARRYING OUT THE INVENTION
Number 1 in FIG. 1 indicates a variable-speed drive for vehicles, particularly motor vehicles, comprising an outer casing 2 in turn comprising a tubular body 3 and two plates 4 and 5 closing the opposite ends of body 3. Plates 4 and 5 are fitted through with two propeller shafts 6 and 7 aligned with each other and coaxial with an axis 8 substantially perpendicular to walls 4 and 5. Shaft 7 rotates clockwise in FIG. 2, and comprises an end portion 9 projecting inside casing 2 through a hole 10 formed through a plate 11 connected, inside casing 2, to body 3 and parallel and adjacent to plate 5. Portion 9 is connected in rotary and axially-fixed manner to plate 5 by means of a bearing 12, and presents a dead hole 13 coaxial with axis 8 and engaged in rotary and axially-fixed manner by an end portion 14 of shaft 6.
Shafts 6 and 7 are connected angularly integral with each other by means of a connecting assembly 15 housed inside casing 2 and which provides for continuously varying the velocity ratio
REFERENCES:
patent: 2642749 (1953-06-01), Wood
patent: 5575734 (1996-11-01), Rondinelli
Herrmann Allan D.
Nath Gary M.
Novich Harold L.
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