Abstract: There is disclosed a continuously variable ratio transmission assembly (“variator”) comprising a roller which transmits drive between a pair of races, the roller being movable in accordance with changes in variator ratio, a hydraulic actuator which applies a biasing force to the roller, at least one valve connected to the actuator through a hydraulic line to control pressure applied to the actuator and so to control the biasing force, and an electronic control which determines the required biasing force and sets the valve accordingly, wherein the valve setting is additionally dependent upon a rate of flow in the hydraulic line.

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 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: 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 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: 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: 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: There is described a controller for motor vehicle drive train comprising an engine and a continuously variable ratio transmission providing geared neutral, the controller serving to set demands for wheel torque and engine speed in dependence upon a driver input, characterised in that the controller is adapted to respond to input from the driver indicative of a requirement for an engine speed increase prior to vehicle launch by raising engine speed while implementing a reduced wheel torque strategy, and to subsequently raise wheel torque following input from the vehicle driver by which launch is initiated.

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 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: In a multi-regime continuously variable ratio transmission system, the clutch (H) of a new regime is applied substantially instantaneously in a synchronous mode of the transmission to allow the clutch engagement to be based on the actual, rather than the predicted, ratio of the transmission. The transmission system is under the control of a control system applying clutch apply pressure and controlling the setting of the variator forming part of the transmission system, the control of the clutch apply pressure being carried out independently of the control of the variator such that the settings of the variator are unaffected by the variations in the clutch apply pressures.