Planetary gear transmission systems or components – Nonplanetary variable speed or direction transmission... – Nonplanetary transmission is friction gearing
Patent
1991-07-25
1993-06-08
Lorence, Richard M.
Planetary gear transmission systems or components
Nonplanetary variable speed or direction transmission...
Nonplanetary transmission is friction gearing
180297, F16H 3708, B60K 504, B60K 1708
Patent
active
052174182
DESCRIPTION:
BRIEF SUMMARY
This invention relates to drivelines for wheeled vehicles. By "driveline" we mean the assembled series of driving components beginning with the engine or other prime mover, and ending with final driving shafts which rotate about substantially fixed axes and to which wheel units will be connected, typically by way of universal joints and half-shafts, but without including the wheel units, joints and half-shafts themselves. Such a driveline therefore includes the transmission, and a driveline according to the present invention includes a CVT, that is to say a transmission capable of continuous or stepless variation of the transmitted ratio. A particular feature of the present invention is that the driveline should have a slipless connection between the output member of the engine and the input to the CVT, and also the capability of adopting a condition, well known in the art as "geared neutral" or "geared idle", in which for a predetermined transmitted ratio the output member of the driveline is stationary in response to a driven and moving input. One obvious advantage of vehicles with drivelines having this capability is the facility for the driver to hold the vehicle at rest with the CVT under drive, and to move away from rest by simply changing the transmitted ratio, without the essential need for a starting clutch and/or a torque converter and/or some other component which is capable of disconnecting the engine from the transmission or at least of providing substantial slip between them. The present invention is therefore to be contrasted with known drivelines, of the kind shown in Patent Specification GB-A-1175857 for example, which are not capable of geared neutral and which include a torque converter between the engine and the CVT. By the term "slipless" connection we mean to include all connections which are intended, in use, to allow no significant slip between the parts connected: such connections include, for instance, some flexible belts as well as chain drives and gear trains.
The present invention applies particularly, but not exclusively, to drivelines including CVT's in which the ratio-varying component, or variator, is of the toroidal-race, rolling traction type. A well-known feature of such CVT's that their input and output axes of rotation coincide at all times: this promotes radial compactness and is to be contrasted, for instance, with the kind of CVT shown in GB-A-1175857 in which variation of the transmitted ratio is accompanied by relative displacement between the input and output axes of the variator.
The advantages of front-wheel drive vehicles, with drivelines in which the operating axis of the engine lies transverse relative to the vehicle, are now well understood. Where the transmission is a CVT however, and especially a CVT of the toroidal-race rolling traction type, a transverse engine presents a special problem. It is customary to locate the engine and the transmission in-line with their principal operating axes coincident, but the combined length of a typical engine and CVT may exceed the available transverse space in a road vehicle. One object of the present invention is to provide an alternative layout of engine and transmission which enables them to be accommodated together within a smaller transverse vehicle dimension. Another feature of a driveline according to the present invention is the opportunity it offers to provide a reasonable clearance between each of the driven wheels and the adjacent engine or transmission structure, so that the half shafts which are directly connected to the wheels may be of efficient length, and may be substantially equal in length. In some known transverse-engined vehicles the disposition of the engine and transmission structure dictates half-shafts very unequal in length. This has several disadvantages, including larger angular displacements at the shorter end from suspension movements, and unequal torsional stiffness unless the latter is avoided by increasing the diameter of the longer half-shaft.
The invention is defined by the claims, t
REFERENCES:
patent: 2030203 (1936-02-01), Gove et al.
patent: 3371546 (1968-03-01), Spangler et al.
patent: 3453904 (1969-07-01), Dangauthier
patent: 3557636 (1971-01-01), Dangauthier
patent: 4297918 (1981-11-01), Perry
patent: 4693134 (1987-09-01), Kraus
patent: 5090951 (1992-02-01), Greenwood
Fellows Thomas G.
Winter Philip D.
Lorence Richard M.
Ta Khoi Q.
Torotrak (Development) Limited
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