Abstract: A transmission arrangement is disclosed which comprises first and second variators (166, 169) each of which comprises an input race (150, 154) and an output race (152, 156). A plurality of rollers (276, 278) is arranged to run upon the input and output races to transfer drive from one to the other. The races are mounted for rotation about a common axis and the inclination of the first variator's rollers is variable independently of the inclination of the second variator's rollers, so that the two rollers are able to provide independently and continuously variable drive ratios. To provide traction between the rollers and races, a biasing device (216, 217) applies an axial force to one of the races, urging the rollers and races into engagement with each other. Each variator is provided with a shunt gear for providing forward, reverse and g eared neutral ratios, and to couple the variator input to the shunt gear a coupling member (160) passes through the outer variator races.

Abstract: A method is disclosed for obtaining a signal representing motor vehicle acceleration. The method involves obtaining a high pass filtered vehicle acceleration signal and a low pass filtered vehicle acceleration signal. One of these signals (preferably the high pass filtered signal) is obtained based upon the net driving force applied to the vehicle, which can be used to obtain an estimate of acceleration by means of an adoptive vehicle model (28). The other signal is obtained by measurement, for example by differentiating a measured vehicle speed signal with respect to time. Adding the two filtered signals together gives a vehicle acceleration signal of potentially good quality.

Abstract: A fraction control arrangement for a variator (10) with a pair of races (12, 14, 26) and at least one roller (28) which transfers drive from one to the other. The roller is movably mounted. Its motion enables the speed of one race to be varied relative to the speed of the other race. The variator has a hydraulic traction load actuator (117) which receives a hydraulic traction load pressure and in response urges the races and the rollers into engagement in order to provide traction between them. At least one hydraulic roller control actuator (32) receives opposed first and second reaction pressures and in response to apply a reaction force to the roller. A traction control valve (119, 119a) controls the traction load pressure and is operable in at least two modes. The relationship between traction load pressure and reaction force is different in the two modes.

Abstract: The invention is concerned with a continuously variable transmission incorporating a variator of the type having at least two co-axial races (D1-D4) between which drive is transferred at a continuously variable variator ratio. The variator races are mounted for rotation about a variator shaft (16). The transmission has a layshaft (18) which is laterally separated from the variator shaft. It has two epicyclic gears. A splitter epicyclic (14) has an input member driven from the transmission input (10) and two output members arranged respectively to drive the layshaft and the variator shaft. A recirculater epicyclic has first and second input members for coupling respectively to the variator shaft and to the layshaft and a recirculater output member. An arrangement of clutches is provided for selectively engaging any of at least three regimes. In one regime the recirculater output member drives the transmission output. In another the layshaft drives the transmission output.

Abstract: An arrangement is disclosed for providing an “end-stop” function for a variator in a continuously variable transmission. The variator (8) needs some arrangement for preventing its own drive ratio from going beyond a ratio limit. In accordance with the present invention, this is provided by means of a one-way clutch (22 or 24). The one-way clutch is coupled to both the variators input and its output, and is arranged to engage (lock up) when the variator reaches its ratio limit, so that the variator is prevented from going beyond the limits. The invention is particularly suited to use with transmissions which provide two regimes and a synchronous change between them.

Abstract: A variator transmission comprises an input disc (10), an input disc drive shaft (20) on which the input disc is mounted, a transmission input shaft (28) for rotating the input disc drive shaft (20), an output disc (12) facing the input disc and arranged to be rotatable coaxially therewith. The input and output discs have a toroidal cavity, rollers (14, 16), means for varying the inclination of the rollers, means (40, 42, 44) for applying to one of the input disc (10) and the output disc (12) a first end load proportional to the input torque applied by the transmission input shaft (28) and means (52, 54, 56) for applying a second end load proportional to the output torque of the variator.

Abstract: An apparatus is disclosed for supplying fluid to a continuously variable transmission which has a lubrication system and at least one transmission control system. The apparatus comprises first and second pumps (120, 122). The first pump has an output which is connectable to the lubrication system through a supply control valve arrangement (132). The second pump has an output which is connectable to the transmission control system. The apparatus has a transfer passage (128) through which the first pump can be connected to the transmission control system. The supply control valve arrangement is adapted to selectively throttle supply of fluid from the output of the first pump to the lubrication system in order to cause fluid output from the first pump to be diverted through the transfer passage to the transmission control system.

Abstract: The invention concerns a method of operating a motor vehicle powertrain comprising an infinitely variable transmission and an engine. The transmission comprises a rotary transmission input coupled to the engine, a rotary transmission output coupled to the vehicle wheels, a variator which provides a continuously variable ratio (the “variator ratio”), and gearing for coupling the variator between the engine and the transmission output in such a manner that the ratio of transmission output speed to transmission input speed (the “reciprocal transmission ratio”) is a function of the variator ratio. The available range of variator ratios maps onto both forward and reverse reciprocal transmission ratios, and at a particular variator ratio (the “geared neutral ratio”) the transmission output is stationary despite its being coupled through the transmission to the rotating transmission input.

Abstract: A transmission comprises a toroidal variator having first and second spaced-apart drive discs (12, 14) defining a toroidal cavity about a rotational axis (x-x), a transmission input (22) arranged to drive the first and second drive discs (12, 14) in opposite directions and supported on pivotal mountings between the drive discs (12, 14), one or more rollers (18, 20) arranged to contact the said drive discs (12, 14) and be driven thereby, wherein the transmission output (44) is driven by orbiting of the pivotal mountings around the rotational axis of the variator.

Abstract: An arrangement for controlling a variator in a continuously variable transmission such as a vehicle transmission is described. The arrangement comprises a user operable ratio control part such as a lever and a device for operatively coupling the ratio control part to a movable torque transfer part of the variator such as its rollers. The coupling device is, in the particular embodiment described, a hydro-mechanical arrangement. By moving the user operable ratio control part, the user exercises control over the variator ratio. In accordance with the invention the arrangement further comprises a torque release device such as a valve which is operable by the user to decouple the ratio control part from the movable torque transfer part. By doing so, the torque release device offers functionality which is in some ways analogous to that of a clutch in a conventional stepped ratio vehicle transmission.

Abstract: A method for controlling a continuously variable ratio transmission is described. The method may include controlling a continuously variable ratio unit (“variator”) having rotary input and output members through which the variator is coupled between an engine and a driven component, the variator receiving a primary control signal and being constructed and arranged to exert upon its input and output members torques which correspond directly to the control signal. The method may also include determining a target engine acceleration, determining settings of the variator's primary control signal and of an engine torque control for providing the required engine acceleration and adjusting the control signal and/or the engine torque control based on these settings, predicting a consequent engine speed change, allowing for engine and/or transmission characteristics, and correcting the settings of the control signal and engine torque based on a comparison of actual and predicted engine speeds.

Abstract: A continuously variable transmission having a variator (5) comprising input discs (2) coupled to an input shaft (12) and an output disc (3) providing a rotary variator output. The input and output discs are mounted for rotation about a common axis and at last one roller (4) is arranged between the discs to transfer drive from one to the other at a continuously variable variator drive ratio. The roller is mounted in a carrier (30) in a manner which permits it to spin about its own axis and to tilt relative to the disks to vary the variator drive ratio. A hydraulic actuator (22) is arranged to apply to the carrier (30) a reaction force determined by a hydraulic pressure difference acting on the actuator. The reaction force opposes a traction force applied to the roller (4) by the action of the discs (2, 3).

Abstract: A variator (2) having a pair of semi-toroidally recessed races (11, 12) mounted to a housing (6) for rotation about a common variator axis. A roller (14) is mounted between the races to transfer drive between them at a variable drive ratio. A sun gear (25) is mounted between the races, as is a ring (gear 26). The ring gear is radially outboard of the sun gear. Mounted between the sun and ring and meshing with both is a carrier gear (33) upon which the roller is mounted in a manner which enables it to both spin about its own axis, when turned by the races, and also to tilt relative to the races to vary the drive ratio. A control pinion (27) is also arranged between the sun and ring gears meshing with both. The control pinion is able to rotate about its own axis freely, but the pinion axis is fixed with respect to the housing.

Abstract: A multi-regime continuously variable ratio transmission has a transmission input shaft, a transmission output shaft, and a ratio varying unit having a rotating input and a rotating output, the rotational axes of the input and the output being coaxial. A shunt having first and second epicyclic gear sets is connected across the ratio varying unit. One gear set has an input driven by the input shaft and an input driven by one side of the ratio varying unit and the other gear set has an input from the first gear set and an input from one side of the ratio varying unit. The gear sets rotate about a common axis and are offset with respect to, and parallel to, the rotational axes of the input and output of the ratio varying unit. A clutch is operable to selectively connect the output of the second gear set to the output shaft.

Abstract: In a continuously variable transmission (“CVT”) using a toroidal-race continuously variable ratio device and a planetary gear mechanism, the rotation of the input shaft (12) is directly transmitted to the carrier C of the planetary gear mechanism (61), and rotation resulting from gearing and reversal by the variator (5) is transmitted to the sun gear (S1). When the low clutch L is engaged, the rotation of the ring gear (R3) is transmitted via the reversing gear mechanism (71) to the output shaft (13), and when the high clutch H is engaged, the rotation of the sun gear (S2) is transmitted to the output shaft (13).

Abstract: There is described a method of controlling a continuously variable ratio transmission of the type comprising a continuously variable ratio unit (“variator”) which has rotary input and output members though which the variator is coupled between an engine and a driven component, the variator receiving a primary control signal and being constructed and arranged such as to exert upon its input and output members torques which, for a given variator drive ratio, correspond directly to the control signal, the method comprising: determining a target engine acceleration, determining settings of the variator's primary control signal and of an engine torque control for providing the required engine acceleration and adjusting the control signal and/or the engine torque control based on these settings, predicting a consequent engine speed change, allowing for engine and/or transmission characteristics, and correcting the settings of the control signal and engine torque based on a comparison of actual and predicted engine

Abstract: A variator (10) has two races (12, 12) mounted for rotation about a common axis. Opposed, shaped faces (14, 18) of the races define an annular space containing at least one roller (38, 40) which runs upon the races to transfer drive between them. The roller is mounted on a carrier (42, 44) in such a way that its inclination to the common axis is able to change, to enable changes in variator ratio. The rollers and their carriers are controlled through a mechanism comprising a sun (46, 48) and a ring (50, 52) with which the carrier engages. Relative rotation of the sun and ring causes a tipping motion of the carrier (42, 44), so that the rollers steer themselves to a new inclination. To control the sun and ring, there is provided a planet (100) which engages them both. The rotational position of the carrier is controlled independently of its engagement with the sun and the ring.

Abstract: A variator transmission comprises an input shaft (18), an input disc (10) mounted on the input shaft for rotation therewith and an output disc (12) facing the input disc and arranged to rotate coaxially therewith, the input and output discs defining between them a toroidal cavity. Two rollers (14, 16) are located in the toroidal cavity and first and second roller carriage means are provided upon which the first and second rollers respectively are rotatably mounted and end load means (34, 36) urge the rollers into contact with the input and output discs to transmit drive. The two roller carriage means are mounted on opposite sides of the pivotal axis of a lever (50) and the pivotal axis of the lever (50) is movable in the radial direction with respect to the rotational axis of the input and output discs.

Abstract: A continuously variable ratio device (“variator”) is disclosed in which a pair of rotary races (252, 254) is mounted for rotation about a common variator axis (218). Drive is transferred from one race to the other through at least one roller (200) running upon them. The drive ratio is variable by virtue of precession of the roller about a precession axis (228). Precession results in a change in angle between the roller axis and the variator axis and a corresponding change in drive ratio. In accordance with the invention, the roller (200) is coupled to a carrier (214) in a manner which permits it to precess relative to the carrier (214). The carrier itself is rotatable about a carrier axis (226) which is non-parallel to the precession axis. Rotation of the carrier (214) about the carrier axis serves to change the orientation of the precession axis (228) and is accompanied by a change in variator drive ratio.

Abstract: A continuously variable ratio transmission unit having a housing (116) and input (102, 106) and output (100) discs paired to define first and second toroidal cavities. The discs (100, 102, 106) are mounted to the housing for rotation about a common axis. First (110) and second (112) rollers—or more typically first and second sets of rollers—are respectively arranged in the first and second cavities and serve to transmit drive between the input and output discs. First (130) and second (148, 150, 152) actuators act on the respective rollers. The first actuator is coupled to a first carrier part (126) which can be mated with the housing introducing it to the housing along a direction generally parallel to the variator axis. The second actuator is coupled to a second carrier part (146) which can be mated with the housing by introducing the second carrier part to the housing along a direction non-parallel to the variator axis.