Abstract: A continuously variable ratio transmission unit having first and second discs mounted for rotation about a main axis, a toroidal cavity being defined between the discs by facing surfaces thereof and containing a plurality of rollers which serve to transmit drive from one disc to the other, each roller being coupled to a respective carriage through a respective bearing arrangement and each carriage being coupled at a first extremity to a first linear actuator and at a second extremity to a second linear actuator whereby the carriage is movable along a direction transverse to the main axis, the first and second linear actuators working in opposition to exert an adjustable net force on the carriage, the orientation of the carriage being constrained and the bearing arrangement being such as to enable the roller to rotate about a roller axis to thereby transmit drive from one of the discs to the other and also being such as to enable the roller axis to precess relative to the carriage to vary the transmission rati

Abstract: A continuously variable transmission is disclosed comprising a transmission input and output between which a variator (V) can be coupled, in either a low regime or a high regime, by gearing (R1, R2, R3, M). The relationship between variator ratio and overall transmission ratio is different in the two regimes. Incorporated in the gearing are first and second clutch means (L, H) both hydraulically actuated, for engaging and disengaging low and high regimes respectively. The gearing provides a synchronous ratio at which a change between low and high regimes, at constant variator ratio, provides no change in the overall transmission ratio. The transmission is provided with hydraulics which incorporate a shift valve (110) which controls application of hydraulic pressures to the first and second clutch means. A change in state of the shift valve (110) causes one clutch means to change from engaged to disengaged and the other to make the opposite transition.

Abstract: A multiple-regime continuously variable ratio transmission system has a system input shaft (I), a system output shaft (0) and a continuously variable ratio transmission unit (variator) connected to the system input shaft and having a variator output shaft. A first mixing epicyclec gear train (P1) having inputs drivably connected to the variator output shaft (V) and the system input shaft via a first clutch (H) and a second mixing epicyclic gear train having inputs drivably connected to the variator output shaft and the system input shaft has an output (28) connected to a third epicyclic gear train (E2) having an output which is selectively connectable to the to the system output shaft via a first braking element (L). A second braking element (B) is adapted to lock the output (28) of the second mixing epicyclic gear train in a stationary position.

Abstract: A fluid display arrangement is disclosed for a rolling-traction continuously-variable ratio transmission unit in which drive is transmitted from one race to another by at least one rotating roller whose outer circumference engages the races, the fluid supply arrangement comprising a shroud mounted in proximity to the roller and a fluid supply conduit, and being characterised in that the shroud has an inner surface providing a circumferential portion adjacent the roller's outer circumference and two radially extending portions adjacent respective flanks of the roller, a fluid receiving chamber being thereby defined between the roller and the shroud, and the fluid supply conduit being arranged to deliver fluid into the fluid receiving chamber.

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 multi-regime continuously variable ratio transmission system has coaxial system input and output shafts (16, 24), a continously variable ratio transmission unit (V) connected coaxially to the system input shaft (16) and having a coaxial variator output shaft (18) and a mixing epicyclic gear train (E1) having an input sun gear (S1) drivably connected to the variator ouput shaft (18), a planet carrier (C1) drivably connected to the system input shaft (16) and a planet gear (P1) mounted on the planet carrier ((C1). The planet gear (P1) drives a first intermediate output shaft (22) arranged coaxially with the system input shaft (16) and selectively connectable to the system output shaft via a first clutch (H) in high-regime operation of the transmission. The planet gear (P1) also provides the input for a second epicyclic gear train (E2) having an output (C2) which is selectively connectable to the system output shaft via a braking element (L) for low-regime operation of the transmission.

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: A continuously variable ratio transmission (CVT) comprises a ratio varying unit (“variator”), a first epicyclic (18) having two inputs (A2, S2) connected to opposite sides of the variator (V), a second. epicyclic (16) having an input (C1) driven by a prime mover (12) and components (A1, S1) connected to opposite sides of the variator, a final drive shaft (14), a low regime clutch (L) for selectively connecting the output of the first epicyclic to the final drive shaft in low regime and a third, mixing, epicyclic (20) connected to the output (C2) of the first epicyclic (18) and connected or connectable (F, R) to the variator and being connectible with the final drive shaft in high regime by way of a high regime clutch (F). The high and low regimes are coincident at least one variator ratio (or, more preferably, the operation ranges overlap) and the variator operates in opposite directions in the low and high regimes.

Abstract: A variator assembly comprising a variator of the toroidal-race rolling-traction type. The assembly has input and output discs and rollers which are acted on by hydraulic roller control actuators. They are positioned between the discs to transmit torque from one disc to the other. Hydraulic end loading means supplied with fluid at an end load pressure to apply an end load to bias the discs and the rollers toward each other, thereby enabling the transmission of torque. Reaction pressure supply means are connected to the roller control actuators to cause them to apply an adjustable reaction force to the rollers. The assembly also has hydraulically influenced valve means which serve to compare an input related to the end load pressure with an input related to the reaction pressure and to control the end load pressure in dependence upon the comparison, thereby maintaining a relationship between the end load and reaction pressures.

Abstract: A hydraulic control circuit is disclosed for a continuously variable transmission comprising a continuously variable ratio transmission unit (“variator”) 10, the circuit comprising a supply line 106 and means (which may take the form of a pump 110) for providing a flow of pressurised fluid in the supply line, means (which may comprise a pressure control valve 116) for generating a back pressure in the supply line, and at least one connection for feeding fluid from the supply line to a hydraulic actuator 100 acting on a movable torque transmission 23-37 element (which may comprise a roller 28) of the variator 10. The valve means 152 connected to the supply line allows pressure in the supply line to be selectively modified in response to rate of flow in the supply line.

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 continuously variable transmission is disclosed comprising a transmission input, a transmission output, and a continuously variable ratio unit (“variator”) arranged to be coupled between the transmission input (205) and output (240) by means of at least one clutch (230,250) thereby to enable transfer of drive between the input and the output at a continuously variable transmission ratio. The variator is connected to a hydraulic control circuit (50) and so subject to a hydraulic control pressure which is adjustable by the control circuit and is also influenced by changes in variator ratio. The variator is constructed and arranged such as to adjust its ratio to provide a variator reaction torque which corresponds to the control pressure. The transmission further comprising means (311,310) for adjusting the torque capacity of the clutch while it is engaged so that by controlling torque loading applied to the variator, the clutch influences the control pressure and the reaction torque.

Abstract: A multi-regime continuously variable ratio transmission system has coaxial system input and output shafts (16, 24), a continously variable ratio transmission unit (V) connected coaxially to the system input shaft (16) and having a coaxial variator output shaft (18) and a mixing epicyclic gear train (E1) having an input sun gear (S1) drivably connected to the variator ouput shaft (18), a planet carrier (C1) drivably connected to the system input shaft (16) and a planet gear (P1) mounted on the planet carrier ((C1). The planet gear (P1) drives a first intermediate output shaft (22) arranged coaxially with the system input shaft (16) and selectively connectable to the system output shaft via a first clutch (H) in high-regime operation of the transmission. The planet gear (P1) also provides the input for a second epicyclic gear train (E2) having an output (C2) which is selectively connectable to the system output shaft via a braking element (L) for low-regime operation of the transmission.

Abstract: A hydraulic circuit for a continuously variable transmission having a continuously variable ratio unit that is controlled by at least one hydraulic actuator acting on a movable torque transmission element. The actuator has opposed first and second working chambers. The circuit includes first and second flow lines that are connected to two respective actuator working chambers. The lines feed fluid thereto and therefrom A pressurized supply of fluid urges fluid flow through the flow lines. A variable control valve is incorporated in both flow lines. Each valve generates an adjustable back pressure therein. A further valve is connected between the two flow lines. The further valve has a variable opening and is located upstream of the variable control valve. Opening of the further valve enables flow fluid from one flow line to the other to reduce pressure difference between the lines.

Abstract: A control unit for an infinitely-variable-ratio transmission. The transmission includes a cylinder and a piston with a proximal and a distal end. A support stem is connected to the piston. The piston is hollow and has a head portion for interaction with an associated actuation fluid. A proximal portion extends away from the head portion. The support stem is connected to the proximal portion by an articulated joint and extends from the joint to the head portion to exit from the distal end of the piston.

Abstract: A control system for a multi-regime continuously variable ratio transmission system. The system has input and output shafts and a continuously variable ratio transmission unit (“variator”) connected to the input shaft. Also included is a mixing epicyclic gear train with a first input gear coupled to the input shaft, a second input gear connected to the variator output and an output gear driving an output shaft. Fluid-pressure actuated clutches engage the outputs and ratio combinations to operate the CVT in a number of regimes. The control system includes means for engaging the clutch of a new regime, retaining both clutches engaged in a synchronous mode and disengaging the clutch of the old regime. The control system also has means for applying fluid pressure to engage the new regime clutch in a single stage at the maximum available clutch engaging fluid pressure.

Abstract: A control system (34) suitable for controlling the rollers (26) in an infinitely-variable-ratio transmission (10) is provided with an hydraulic piston arrangement (36) in which a roller support stem (38) is connected to a proximal end (42) of said piston and passes through a piston head (40) via hollow portion (44) within said piston (36) before exiting therefrom.

Abstract: A variator transmission apparatus (10) comprises an input shaft (12), one or more input discs (14, 16) mounted on the shaft for rotation therewith, one or more inner discs (18, 20), the input and output discs defining between them one or more toroidal cavities, a plurality of rollers (22, 24) located within the one or more cavities for transmitting rotation from the outer disc(s) (14, 16) to the inner disc(s) in which means are provided for preventing the end load locking the inner discs (18, 20) to the shaft (12).

Abstract: The present invention provides an hydraulic control circuit for a continuously-variable-ratio transmission An hydraulic control circuit for a CVT transmission includes a first hydraulic pressure control valve V1 for controlling the pressure of hydraulic fluid to be supplied to the roller control pistons of the variator and a second hydraulic pressure control valve V2 for controlling the pressure of hydraulic fluid to be supplied to a clutching arrangement of the transmission. Said valves V1, V2 are connected in flow series and by a first fluid directing valve means V3(S1, S2) for directing flow from each pump PL, PR to a first point P upstream of valve V1 or to a second point P downstream of valve V1 but upstream of valve V2. By adopting such an arrangement it is possible to control the clutches without affecting the roller position and vice versa.

Abstract: Disclosed is a supply of hydraulic actuation and cooling fluid to the roller actuation pistons and rollers provided in an infinitely variable transmission. The transmission assembly (10) includes a split casing (12a, 12b) and a manifold (28) that comprises one or more channels (30, 32, 60) formed in a surface of the casing formed by the split. The provision of said manifold in this position allows for easier manufacture and better performance.