Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16H—GEARING
  • F16H15/00—Gearings for conveying rotary motion with variable gear ratio, or for reversing rotary motion, by friction between rotary members
  • F16H15/02—Gearings for conveying rotary motion with variable gear ratio, or for reversing rotary motion, by friction between rotary members without members having orbital motion
  • F16H15/04—Gearings providing a continuous range of gear ratios
  • F16H15/06—Gearings providing a continuous range of gear ratios in which a member A of uniform effective diameter mounted on a shaft may co-operate with different parts of a member B
  • F16H15/32—Gearings providing a continuous range of gear ratios in which a member A of uniform effective diameter mounted on a shaft may co-operate with different parts of a member B in which the member B has a curved friction surface formed as a surface of a body of revolution generated by a curve which is neither a circular arc centered on its axis of revolution nor a straight line
  • F16H15/36—Gearings providing a continuous range of gear ratios in which a member A of uniform effective diameter mounted on a shaft may co-operate with different parts of a member B in which the member B has a curved friction surface formed as a surface of a body of revolution generated by a curve which is neither a circular arc centered on its axis of revolution nor a straight line with concave friction surface, e.g. a hollow toroid surface
  • F16H15/38—Gearings providing a continuous range of gear ratios in which a member A of uniform effective diameter mounted on a shaft may co-operate with different parts of a member B in which the member B has a curved friction surface formed as a surface of a body of revolution generated by a curve which is neither a circular arc centered on its axis of revolution nor a straight line with concave friction surface, e.g. a hollow toroid surface with two members B having hollow toroid surfaces opposite to each other, the member or members A being adjustably mounted between the surfaces

Definitions

• 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.
• CVT's continuously-variable-ratio transmissions
• 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.
• 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
• specification EP-B-0133330 shows an example of many more recent proposals in which the roller carriages directly contact hydraulic pistons.
• 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.
• 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.
• 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 roTler carriage that is comparable in simplicity and cheapness to the mountings described in WO 90/05860.
• the invention is defined by the claims, the contents of which are to be read as included within the body of this specification, and includes a roller control system as described with reference to the accompanying simplified drawings. Embodiments of the invention will now be described by way of example with reference to those drawings in which:-
• Figure 1 shows one roller assembly and operating mechanism in section
• Figure 2 shows another roller assembly, with certain features shown schematically only;
• FIG. 3 shows another roller assembly and operating mechanism in section
• Figure 4 is a similar view of yet another assembly and mechanism.
• a roller 1 carrying an axle 2, is mounted in roller bearings 3 supported by a carriage 4. Because they are of roller form, the bearings 3 hold the roller axis 5 fixed relative to carriage 4, but allow the roller centre 6 limited freedom of movement along that axis.
• Carriage 4 is connected by a hinged or other pivotal joint 7, permitting rotation about a single axis 8 only, to a rod 9 forming part of an operating mechanism indicated generally at 10.
• Rod 9 carries pistons 11 and 12 which operate within aligned cylinders 13 and 14, connected by ports 15 and 16 to a controlled pressure fluid source 17.
• the structure of cylinders 13 and 14 is anchored to a fixed part 19 of the CVT.
• the roller In operation, in a manner analogous to that described in publication W0 90/05860, the roller will be positively located by only three points of contact with adjacent mechanism, namely its contacts with the input and output discs (not shown) between which it is transmitting traction, and its point of contact with its operating mechanism 10, which may be regarded as the centre 21 of the hinge joint 7.
• the ratio transmitted by roller 1 between its associated input and output discs is determined by the position of pistons 11, 12 relative to their operating axis 20, and that position in turn reflects the balance between the force (along axis 20) of the disc/roller reactions, and the nett hydraulic force acting upon pistons 11, 12 by reason of the nett hydraulic pressure set up in cylinders 13, 14 by the source 17 and its associated control.
• the necessary degrees of freedom of movement, to allow roller centre 6 to follow Its appropriate locus between the Input and output discs as the ratio changes, is provided by :-
• Figure 2 shows a minor modification of the axle mounting of Figure 1, in which instead of that axle 2 being free to slide within the roller bearings 3, the bearing members (3a) are fixed to the axle but themselves have limited freedom of axial sliding within their outer sleeves 25.
• Figure 2 also shows, schematically and more importantly, how the mechanism of Figure 1 could be modified if the double-acting piston-and-cyUnder combination (11-14) of that Figure were replaced by a single-acting piston and cylinder 26, 27.
• an abutment 28 on the opposite end of carriage 4 now contacts a piston 29, operating within a hydraulic cylinder 30 which may also be controlled from source 17.
• the locus of contact between items 28, 29 is variable, so that this contact does not add to or subtract from the degrees of freedom and restraint already described, and the sole effect of piston 29 upon the roller assembly is to exert a return force which items 26, 27 would themselves exert if they were double-acting, as with items 11-14 in Figure 1.
• Chambers 36 and 37 are now connected to source 17 by way of cooperating ports 46 in spigot 42 and ring conduits 47 in part 19.
• the necessary degrees of freedom to enable roller centre 6 to follow its appropriate locus, as the CVT changes ratio, are now given by:- 1. the freedom of centre 6 to move axially within roller bearings 3, as in Figure 1;
• a hinge - e.g. items 7 in Figures 1 to 3, and the hinge about axis 45 in Figure 4 - can be cheaper and can package better than joints allowing relative rotation about more than one axis, as shown in some of the embodiments in publication WO 90/05860, for example.
• the hinge or swivel joints (about axes 8, 45), just described, ensure that the associated pistons (11, 12, 35) of the operating mechanisms will rotate in their cylinders whenever the roller centre is displaced along axis 20, and the CVT therefore changes ratio.

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• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Friction Gearing (AREA)

Priority Applications (5)

Applications Claiming Priority (2)

Publications (1)

Family

ID=10687435

Family Applications (1)

Country Status (8)

Cited By (2)

Families Citing this family (3)

Citations (5)

Family Cites Families (1)

• 1990
  • 1990-12-21 GB GB909027795A patent/GB9027795D0/en active Pending
• 1991
  • 1991-12-12 IN IN1227DE1991 patent/IN185323B/en unknown
  • 1991-12-18 JP JP04501448A patent/JP3091915B2/ja not_active Expired - Fee Related
  • 1991-12-18 DE DE69108931T patent/DE69108931T2/de not_active Expired - Fee Related
  • 1991-12-18 AU AU90970/91A patent/AU9097091A/en not_active Abandoned
  • 1991-12-18 EP EP92901359A patent/EP0561949B1/en not_active Expired - Lifetime
  • 1991-12-18 WO PCT/GB1991/002261 patent/WO1992011475A1/en not_active Ceased
  • 1991-12-18 ES ES92901359T patent/ES2072748T3/es not_active Expired - Lifetime
• 1993
  • 1993-06-21 GB GB9312766A patent/GB2267133B/en not_active Expired - Lifetime

Patent Citations (5)

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