CONTINUOUSLY VARIABLE TOROIDAL TRANSMISSION
In a toroidal variator a plurality of rolling elements ( 20,22 ) are in driving engagement with an input and output race ( 10, 14 ) at respective contact regions. Each rolling element ( 20, 22 ) is mounted on a carriage assembly ( 26 ) for rotation about a rolling axis, and is being free to pivot about a tilt axis, the tilt axis passing through the rolling element ( 20, 22 ) perpendicular to the rolling axis, and intersecting the rolling axis at a roller centre, whereby a change in the tilt axis causes a change in the variator ratio being the ratio of rotational speeds of the races. The tilt axis is arranged at an angle known as castor angle (see FIG. 4 ) to a plane (P) perpendicular to the variator axis (V). Each carriage assembly ( 26 ) can cause a movement of the rolling element ( 20, 22 ) with a component of rotation about a pitch axis (A, B). The pitch axis is defined as passing through the roller centre and through the contact regions. Pitching the roller elements ( 20, 22 ) causes them to tilt, thereby changing the transmission ratio.
1 . A variator comprising:
an input surface and an output surface, the input and output surfaces being coaxially mounted for rotation about a variator axis, and a toroidal cavity being defined between the working surfaces;
a plurality of rolling elements disposed between and being in driving engagement with the input and the output surfaces at respective contact regions, each rolling element being mounted on a carriage assembly for rotation about a rolling axis, each rolling element being free to pivot about a tilt axis, the tilt axis passing through the rolling element perpendicular to the rolling axis, and intersecting the rolling axis at a roller centre, whereby a change in the variator ratio being the ratio of rotational speeds of the races occurs with a change in tilt angle;
wherein each carriage assembly is mounted for pivotal movement about a pitch axis that results in a change of a pitch angle of the rolling element, the pitch axis passing through the roller centre and through the contact regions;
the variator further comprising a control member operative to actuate at least one of the carriage assemblies to undertake the said pivotal movement thereby changing the pitch angle, so urging the plurality of rolling elements to pivot about their tilt axes and thereby provide a change in variator ratio; and
a reaction member operatively coupled to the plurality of rolling elements such that it bears the reaction torque from the rolling elements within the toroidal cavity and is movable in a radial direction relative to the variator axis and optionally is movable in a non-radial direction such that the reaction member balances reaction loads generated by each rolling element within the toroidal cavity.
2 . (canceled)
3 . A variator according to claim 1 in which reaction torque is borne by the reaction member separately from the control member.
4 . A variator according to claim 1 in which the reaction member is pivotally coupled to the centre of each rolling element.
5 . (canceled)
6 . (canceled)
7 . A variator according to claim 1 comprising a damper to dampen movement of the reaction member.
8 . A variator according to claim 1 comprising a reaction member wherein the reaction member comprises a mechanical end-stop to limit movement of the reaction member in a radial direction relative to the variator axis.
9 . A variator according to claim 1 in which the reaction member is mounted for rotation about the variator axis in response to reaction torque arising from the disc to rolling element contact thereby changing the variator ratio.
10 . (canceled)
11 . A variator according to claim 1 in which the roller carriage centre has radial float with resect to the variator axis relative to the reaction member.
12 . A variator according to claim 1 in which the reaction member has float in the direction of the variator axis.
13 . A variator according to claim 1 comprising resilient means against which the reaction member may be urged in response to a reaction torque.
14 . A variator according to claim 1 in which each carriage assembly is actuated at an actuation point radially distant from the pitch axis such that the carriage undergoes pivotal movement about the pitch axis.
15 . A variator according to claim 1 in which each actuation point is offset from the centre plane of the toroidal cavity in a direction parallel to the variator axis.
16 . A variator according to claim 1 in which a castor axis for each rolling element extends through the centre of the rolling element and its actuation point.
17 . (canceled)
18 . A variator according to claim 1 in which each rolling element and its respective carriage assembly together have four points of contact, the points of contact being at the input surface, the output surface, an actuation point and a reaction point.
19 . A variator according to claim 1 in which the control member is adapted to provide actuation by translational movement.
20 . A variator according to claim 1 in which the control member actuates the carriage assembly at a location radially outward of a cylindrical surface which is parallel to the variator axis and tangential to the periphery of the larger of the input surface and output surface.
21 . A variator according to claim 1 in which the respective carriage assemblies are actuated simultaneously.
22 . (canceled)
23 . A variator according to claim 1 comprising a single control member on which the carriage assemblies are mounted.
24 . (canceled)
25 . (canceled)
26 . A variator according to claim 1 in which each carriage assembly comprises a stem coupled to the control member.
27 . (canceled)
28 . A variator according to claim 1 in which the control member is operatively coupled to the plurality of rolling elements on the same side of a plane that includes the variator axis.
29 . A variator according to claim 1 in which the toroidal cavity contains not more than two rolling elements.
30 . A variator according to claim 1 comprising power means to actuate the control member having a power output of less than 20 W.
31 . (canceled)
32 . (canceled)
33 . A variator according to claim 1 in which movement of each carriage about the pitch axis is achieved by a single translational input substantially perpendicular to the carriage reaction force.
34 . (canceled)
35 . A variator according to claim 1 in which movement of each carriage about the pitch axis is achieved by means of a single actuator for all roller carriages of the variator.
36 . A variator according to claim 1 that is a full-toroidal variator.
37 . A variator according to claim 1 further comprising:
a second input surface and a second, facing output surface defining a second toroidal cavity;
a second plurality of rolling elements disposed between the second input and second output surfaces and being in driving engagement with the second input and the second output surfaces at respective contact regions, each rolling element being mounted on a carriage assembly for rotation about a rolling axis, each rolling element being free to pivot about a tilt axis, the tilt axis passing through the rolling element perpendicular to the rolling axis, and intersecting the rolling axis at a roller centre, whereby a change in the variator ratio being the ratio of rotational speeds of the races occurs with a change in tilt angle;
wherein each carriage assembly is mounted for pivotal movement about a pitch axis that results in a change of a pitch angle of the rolling element, the pitch axis passing through the roller centre and through the contact regions;
the control member or a second control member for actuation of the each second carriage assembly to pitch the second plurality of rolling elements resulting in a change in pitch angle and a change in variator ratio;
a first reaction member operatively coupled to the plurality of rolling elements in the first cavity and a second reaction member operatively coupled to the second plurality of rolling elements in the second cavity such that the first and second reaction members bear reaction loads arising from the respective rolling elements.
38 . A variator according to any one of the claim 37 further comprising: a load-sharing assembly operatively linked to the reaction members of the first and second cavities such that reaction torque from the reaction members is balanced.
39 . A drive arrangement for transmitting drive from an engine to an auxiliary unit, the drive arrangement incorporating a variator according to claim 1 .
40 . A drive arrangement according to claim 39 for a supercharging arrangement for an internal combustion engine comprising a supercharger having a rotational drive input a transmission having a rotational drive input to receive drive from an internal combustion engine, and a rotational drive output coupled to the input of the supercharger wherein the transmission includes the variator operatively connected between the input and the output of the transmission.
41 . (canceled)
42 . (canceled)
43 . (canceled)
44 . (canceled)
45 . (canceled)
46 . (canceled)
47 . A variator comprising:
an input surface and an output surface, the input and output surfaces being coaxially mounted for rotation about a variator axis, and a toroidal cavity being defined between the working surfaces;
a plurality of rolling elements disposed between and being in driving engagement with the input and the output surfaces at respective contact regions, each rolling element being mounted on a gimbal on a carriage assembly for rotation about a rolling axis, each rolling element being free to pivot about a tilt axis, the tilt axis passing through the rolling element perpendicular to the rolling axis, and intersecting the rolling axis at a roller centre, whereby a change in the variator ratio being the ratio of rotational speeds of the races occurs with a change in the tilt angle;
wherein each carriage assembly is mounted for pivotal movement about a pitch axis that results in a change of a pitch angle of the rolling element, the pitch axis passing through the roller centre and through the contact regions;
the variator further comprising a control member operative to actuate at least one of the carriage assemblies to undertake the said pivotal movement thereby changing the pitch angle, so urging the plurality of rolling elements to rotate about their tilt axes and thereby provide a change in variator ratio; and
a reaction member operatively coupled to the plurality of rolling elements such that it bears the reaction torque from the rolling elements within the toroidal cavity.
48 . A variator according to claim 47 , wherein the gimbal provides a castor angle for the roller.
49 . A variator according to claim 1 , wherein the carriage assembly comprises a stem which lies in the centre plane of the variator.