Friction gear transmission systems or components – Friction gear includes idler engaging facing concave surfaces – Toroidal
Reexamination Certificate
2000-06-19
2001-11-06
Bucci, David A. (Department: 3682)
Friction gear transmission systems or components
Friction gear includes idler engaging facing concave surfaces
Toroidal
C476S041000
Reexamination Certificate
active
06312356
ABSTRACT:
SUMMARY OF THE INVENTION
1. Field of the Invention
The present invention relates to infinitely-variable-ratio transmission apparatus of the toroidal race rolling friction type, hereinafter referred to as a variator.
2. Discussion of Prior Art
In such apparatus there is employed a main shaft which takes drive from, for example, an engine e.g. an internal combustion engine to two input discs which are mounted on the shaft. Two output discs are mounted back to back between the input discs and are free to rotate relative to the shaft.
In such an arrangement motion is transferred from the input discs to the output discs via a plurality of rollers positioned in toroidal cavities which are provided between the input discs and the output discs.
Single cavity variators are also known in which a single input disc is mounted for rotation on an input shaft and a single output disc faces the input disc in a manner which defines a toroidal cavity in which are situated a plurality of power-transmitting rollers. Whilst such an arrangement is less likely to suffer from the problems outlined herein, it will be appreciated that the present invention can be applied to this single cavity arrangement.
The rollers are subjected to hydraulic forces by an end load device so that they make contact with the faces of the respective input and output discs in order to transmit power from the input discs to the output discs. The power is transferred from the output discs via, for example, a chain drive to a further transmission component such as an epicyclic gear box.
The drive through the chain exerts a transverse load onto the shaft and at high power transmission levels can cause the shaft to flex. The degree of flexing is relatively small but has the potential of causing a significant effect on the position of the two output discs which can cause the load on some of the rollers to be increased i.e. a crushing effect will be applied, whilst the load on some of the remaining rollers will be decreased, thereby not allowing the drive to be transferred efficiently from the input to the output discs.
It will be appreciated that the effect of shaft flexing is in effect a distortion of the toroidal cavities between the input and output discs.
A solution to the above problem can be summarised as accepting a relatively small degree of flexing of the shaft and then providing some compliance in the mounting of the discs such that when the shaft is subjected to flexing the discs are able to rotate in planes which are parallel to one another, and thereby maintain the shape of the cavities.
GB-A436363 discloses a variable speed power transmission mechanism having torus discs and rollers in which one of the discs is mounted on a support shaft by means of one or more teeth or dogs on a front face which engage with a collar keyed to the central shaft. Such an arrangement does provide some degree of relative movement between the disc and shaft but improvement on this design is possible.
SUMMARY OF THE INVENTION
The present invention seeks to provide a transmission apparatus in which one or more of the discs is mounted on the shaft in such a manner that it rotates with the shaft but is capable of adopting a plane of rotation which is other than normal.
Accordingly the present invention provides a variator transmission apparatus comprising an input shaft, one or more input discs mounted on the shaft for rotation therewith, an output disc assembly, the input disc or discs and the output disc assembly defining between them one or more toroidal cavities, a plurality of rollers located in the cavity or cavities and means for applying an end load pressure to maintain the rollers in contact with the respective disc or discs in order to transmit drive, characterised in that one of the discs is mounted on the shaft by means of an intermediate relatively flexible member.
The relatively flexible member can be attached to a sleeve at an inner radial location and the sleeve is attached to the shaft so as to be rotatable therewith.
For example the sleeve can be splined so that it is rotatable with the shaft and axially moveable relative to the shaft.
The relatively flexible member can be attached to the sleeve by means of a clamping ring.
The flexible member can be attached at an outer radial location to a clutch ring.
The clutch ring can be provided with projections which are engageable with corresponding recesses on the said disc; alternatively the disc may be provided with projections which are engageable with corresponding recesses on the clutch ring.
The relatively flexible member can be secured at the said outer radial location by means of an outer clamping ring.
A reaction plate can be mounted on the shaft, the reaction plate having two or more sets of pins, one of which said sets of pins being extendable through clearance openings in the flexible member in order to contact a face of the said one of the discs, the pins of one of the other said sets of pins engaging the relatively flexible member at an inner radial location.
The apparatus can include a clamping nut assembly which is threadedly mounted on the shaft in order to force the reaction plate into contact with the said one of the discs by means of the respective one of the said sets of pins.
The other one of said discs can be mounted for rotation with the shaft, and be provided with abutment means to prevent axial movement
The output disc assembly can be mounted on bearing means which have part spherical co-operating surfaces thereby allowing the disc assembly to rotate relative to the shaft and to adopt a plane of rotation other than normal relative to the shaft.
In a development of the above, the flexible member may also be secured to the reaction plate of the end load mechanism.
In the above development the flexible member may be secured to the reaction plate and the sleeve by means of a bolt arrangement or a rivet arrangement.
In either arrangement, the flexible member may be secured to the disc by means of a bolt or rivet arrangement.
In a still further development, the flexible member in either arrangement may be preshaped or pre-loaded such that upon application of the end load it is substantially perpendicular to the axis of said shaft.
REFERENCES:
patent: 2152796 (1939-04-01), Erban
patent: 2157066 (1939-05-01), Madle
patent: 2984118 (1961-05-01), De Brie Perry
patent: 3087348 (1963-04-01), Kraus
patent: 5368529 (1994-11-01), Machida
patent: 0 420 157 (1991-04-01), None
patent: 2 643 123 (1990-08-01), None
patent: 431199 (1934-10-01), None
patent: A-436 363 (1935-10-01), None
Bucci David A.
Joyce William C
Nixon & Vanderhye P.C.
Torotrak (Development) Limited
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