Control method and controller for a motor vehicle drive train
View Patent ↗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.
1. A controller for a 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 enhanced 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.
2. A controller as claimed in claim 1 wherein the driver input indicative of a requirement for engine speed increase prior to vehicle launch comprises concurrent application of the driver's brake and accelerator controls.
3. A controller as claimed in claim 2 , wherein the driver input by which launch is initiated comprises release of the brake control.
4. A controller as claimed in claim 1 , which is adapted to limit power input to the transmission prior to vehicle launch.
5. A controller as claimed in claim 1 which is for use with a transmission of torque controlled type, the controller being such as to provide a signal to the transmission proportional to the wheel torque to be provided.
6. A motor vehicle drive train comprising a controller as claimed in claim 1 .
7. A method of controlling a motor vehicle drive train comprising an engine and a continuously variable transmission providing geared neutral, the method comprising setting demands for engine speed and wheel torque in dependence upon a driver input and being characterised in that, in response to a driver input indicative of a requirement for an engine speed increase prior to vehicle launch engine speed is raised while a reduced wheel torque strategy is implemented, wheel torque being subsequently raised following initiation of vehicle launch.
8. A method as claimed in claim 7 wherein the driver input indicative of a requirement for engine speed increase prior to vehicle launch comprises concurrent application of brake and accelerator controls.
9. A method as claimed in claim 7 wherein the transmission is of torque controlled type, comprising providing the transmission with a control input proportional to wheel torque.