Transmission of the toroidal-race rolling-traction type

Details Transmission of the toroidal-race rolling-traction type Transmission of the toroidal-race rolling-traction type

1993-07-14

1995-06-13

Wright, Dirk

Friction gear transmission systems or components

Friction gear includes idler engaging facing concave surfaces

Toroidal

476 46, F16H 1538

Patent

active

054237270

DESCRIPTION:

BRIEF SUMMARY
This invention relates to continuously-variable-ratio transmissions (which will be referred to as CVT's) of the toroidal-race, rolling-traction type. It relates in particular to the variators, that is to say the ratio-varying units, of such transmissions in which rollers of variable orientation transmit traction between coaxial and part-toroidal input and output grooves or races, formed on coaxial and rotatable input and output discs respectively. By simultaneously altering the radius from the common axis of the discs at which the rollers make rolling contact with the two races, the relative speeds of the two discs change, so changing the transmitted ratio. While the prior art teaches and the invention will be described with relation to toruses of circular cross-section, the invention includes CVT's in which the torus is generated by rotating any closed figure, of generally circular outline, about a generator line.
It has been common practice in the art for a set of three rollers to transmit traction forces between each input race and its corresponding output race, to mount each roller so that it spins about an axle mounted in a supporting member usually called a carriage, and to interconnect the carriages of all the rollers in each set so that they all transmit the same force at all times.
Automobile applications for CVT's of the toroidal-race rolling-traction type have been the subject of patent applications since the beginning of this century, and especially from the 1920's onwards. Patent specification GB-A-1078791 shows an example of such a CVT in which each roller carriage is directly connected to a mechanical linkage of levers and other solid actuating components, while specification EP-B-013330 shows an example of many more recent proposals in which the roller carriages directly contact hydraulic pistons. In both specifications, each roller is mounted in an elongated carriage which is in turn positively held at both ends by its actuating mechanism. Such a double-ended hold upon each carriage naturally requires many mechanical parts and joints and adds to the size, complexity and cost of the CVT.
Patent publication WO 90/05860 describes a more recent invention which arose from appreciating that the carriages and rollers of this type of CVT can be effectively held and controlled in a manner which involves far less components and mechanical joints, and which therefore offers the prospect of greater simplicity and cheapness. Essentially each carriage and roller is controlled by a hydraulic operating mechanism positvely connected to one end of the carriage only, and each roller assembly is located at all times by only three contacts with adjacent components, namely the two disc-roller contacts and the contact with the operating mechanism.
According to the teaching of the invention of publication WO 90/05860, if it is necessary to exert any force upon the other end of the carriage--for instance because the operating mechanism is only single-acting in operation--that force should be applied in a manner which imposes no positional constraint upon the part of the carriage to which it is applied. The invention described in publication WO 90/05860 is thus to be distinguished from the kinds of prior proposals described, for example, in GB-A-979062, U.S. Pat. No.3,933,054 and GB-A-16OO972, in each of which each assembly of roller and carriage requires to be positively located, in operation, not by three but by four points of contact with adjacent mechanism.
One feature of the invention described in publication WO/90/05860 is that each roller is mounted, within its carriage, in such a way that both the axis and the centre of the roller are fixed relative to that carriage. The present invention arises from appreciating that if for some reason there are advantages in mounting the rollers relative to their carriages in a manner which fixes the roller axis but allows the roller centre some freedom of movement along that axis, it is still possible to achieve a mounting and control of each roller carriage that is comp

REFERENCES:
patent: 3267756 (1966-08-01), Perry et al.
patent: 3933054 (1976-01-01), Iseman

Affiliated with

Also associated with

Rating

Transmission of the toroidal-race rolling-traction type does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Transmission of the toroidal-race rolling-traction type, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Transmission of the toroidal-race rolling-traction type will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-1305904