Vehicle cruise control system and method having improved target speed resolution feature

A constant-speed running system for a vehicle, said system comprising:

• material delivery means for regulating flow of a medium to an engine of said vehicle in accordance with a degree of actuation of said delivery means;
• control means for controlling said degree of actuation of said delivery means;
• an accelerator connected to said control means, said control means being for controlling said degree of actuation of said delivery means responsive to a setting of said accelerator during a manual running mode;
• mode setting means for transferring control to a constant-speed running mode in which a speed of said vehicle is maintained at a target vehicle speed from said manual running mode, and for transferring control to said manual running mode from said constant-speed running mode;
• constant-speed running means for controlling said degree of actuation of said throttle independently of said setting of said accelerator during said constant-speed running mode, said control means being for controlling said degree of actuation of said delivery means responsive to said constant-speed running means during said constant-speed running mode;
• range determining means for determining whether a degree of actuation of said delivery means before transfer of control to said constant-speed running mode is within a given region;
• initial opening setting means for setting, at a time of transfer to said constant-speed running mode, a degree of delivery means actuation before said transfer to an initial delivery means actuation value, responsive to a determination by said range determining means that said degree of actuation of said delivery means before said transfer is within said region, and to a given value responsive to a determination by said range determining means that said degree of actuation of said delivery means is not within said region;
• and
• actuation degree restoring means for setting said degree of actuation of said delivery means to said degree of delivery means actuation before said transfer when said mode setting means transfers control from said constant-speed running mode to said manual running mode.

A method of performing cruise control on an engine of a vehicle, said method comprising the steps of:

• regulating flow of a medium to an engine of said vehicle using a delivery control device;
• controlling a degree of actuation of said delivery control device, said control being performed responsive to a setting of an accelerator during a manual running mode and responsive to a controller, independently of said accelerator, during said constant-speed running mode;
• transferring a control mode from said manual running mode to said constant-speed running mode;
• determining whether a degree of actuation of said delivery control device before performing said transferring step is within a given region;
• setting a degree of delivery control device actuation before performing said transferring step to an initial delivery control device actuation value responsive to a determination by said determining step that said degree of actuation of said delivery control device is within said region, and to a given value responsive to a determination by said determining step that said degree of actuation of said delivery control device before performing said transferring step is not within said region;
• changing said control mode from said constant-speed running mode to said manual running mode;
• and
• resetting said degree of actuation of said delivery control device to said degree of actuation of said delivery control device before performing said transferring step responsive to performance of said changing step.