Transmissions of the toroidal-race rolling-traction type

A CVT of the toroidal race, rolling traction type in which a roller assembly comprises a carriage (67), bearings (64, 65) mounted thereon and a roller (60) defining a roller centre (66) and supported by the bearings for rotation about a roller axis (58), in which the roller contacts and transmits traction forces between coaxial rotatable discs (61, 62) presenting input and output races (85, 87) conforming to different parts of the surface of a single torus and in so doing are subjected to traction forces at the disc/roller contacts (86, 88), and an operating mechanism having a fixed part (72) and a movable part (71), the movable part being reciprocal over a stroke of operating movement and operable to apply a control force to the carriage, and in which the operating mechanism and carriage seek an equilibrium position in which the resultant of the control force and of the traction forces experienced by the roller assembly is zero, wherein

• the single torus defines a mid-plane;
• the carriage includes a rigid structure relative to which the roller axis (58) and the roller centre (66) are fixed;
• the operating mechanism includes constraint means defining a single point (82) of constraint which constrains the operating mechanism to the application of the control force along a force application axis (83) passing through the constraint point (82) and the roller centre (66);
• the constraint point (82) and the disc/roller contacts (86, 88) form a triangular relationship;
• the operating mechanism allows the roller centre (66) freedom to move along two intersecting arcs, about the constraint point (82), which lie in different and intersecting planes
• the equilibrium position of the roller assembly is determined by only the two disc/roller contacts (86, 88) and the position of the constraint point (82);
• and
• the roller (60) is free to rotate about the force application axis.

A CVT of the toroidal race rolling traction type in which a roller assembly comprises a carriage (67), bearings (64, 65) mounted on the carriage and a roller (60) defining a roller centre (66) supported by the bearings, for rotation about a roller axis (58), in which the roller contacts and transmits traction forces between coaxial rotatable discs (61, 62), presenting input and output races (85, 87) conforming to different parts of the surface of a single torus defining a midplane and in so doing are subjected to traction forces at disc/roller contacts (86, 88), and an operating mechanism having a fixed part (72) and a movable part (71), the movable part being reciprocal over a stroke of operating movement and operable to apply a predetermined control force to a location on the carriage, with the control force acting solely along an axis including both the location on the carriage and the roller centre and in which the operating mechanism and carriage seek an equilibrium position in which the resultant of the control force and of the traction forces experienced by the roller assembly is zero when resolved in the same direction in a plane normal to the axis of the discs, wherein:

• the carriage includes a rigid structure relative to which the roller axis (58) and the roller center (66) are fixed:
• the operating mechanism includes means capable of effecting translational movement of the roller centre (66) back and forth along a path dictated by the two disc/roller contacts;
• means allowing the roller (60) freedom to rotate about a diameter thereof so as to change the transmitted ratio of the CVT;
• the axis (58) and the roller centre (66) are fixed relative to the carriage (67);
• the roller centre (66) is positioned to impose no loads on the carriage (67) nor on the operating mechanism other than to produce the balance between the control force and the traction forces experienced by the roller assembly, in the plane normal to the axis of the discs;
• and
• the two disc/roller contacts (86, 88) and the location (82) at which the control force is applied to the roller assembly define a triangular relationship establishing a triangle of forces acting in the same plane.

A CVT of the toroidal race, rolling traction type in which a roller assembly comprises a carriage (67), bearings (64, 65) mounted on the carriage and a roller (60) defining a roller centre (66) supported by the bearings, for rotation about a roller axis (58), in which the roller contacts and transmits traction forces between coaxial rotatable discs (61, 62), presenting input and output races (85, 87) conforming to different parts of the surface of a single torus defining a midplane and in so doing are subjected to traction forces at disc/roller contacts (86, 88), wherein:

• the roller assembly is supported at three points only, namely the two contacts (86, 88) of the roller (60) with the discs (61, 62) and a single point of support (82) defined by a supported operating mechanism that applies a control force to the assembly at the point of support, the single point of support permitting the roller center to freely follow a path dictated by the two disc/roller contacts when the roller assembly is moved by the control force while constraining the application of the control force to a control axis (83) passing through the single point of support (82) and the roller centre (66);
• the operating mechanism and carriage seek an equilibrium position in which the resultant of the control force and of the traction forces experienced by the roller assembly is zero when resolved in the same direction in a plane normal to the axis of the discs;
• the roller (60) is free to rotate about the control axis (83).

A CVT of the toroidal race, rolling traction type in which a roller assembly comprises a carriage (67), bearings (64, 65) mounted on the carriage and a roller (60) defining a roller centre (66) supported by the bearings, for rotation about a roller axis (58), in which the roller contacts and transmits traction force between coaxial rotatable discs (61, 62), presenting input and output races (85, (87) conforming to different parts of the surface of a single torus defining a mid-plane and in so doing are subjected to traction forces at disc/roller contacts (86, 88) wherein:

• a supported operating mechanism has means for applying a control force to a roller assembly always along a control axis (83), passing through a single point (82) of constraint defined by the mechanism and the roller centre (66), means at the constraint point (82) allowing the roller centre freedom to follow a path dictated by the two disc/roller contacts when the roller assembly is moved by the control force, the roller being located by only three points, namely the constraint point (82) and the two disc/roller contacts (86, 88);
• the operating mechanism and carriage seek an equilibrium position in which the resultant of the control force and of the traction forces experienced by the roller assembly is zero when resolved in the same direction in a plane normal to the axis of the discs;
• the roller (60) is free to rotate about the control axis (83).