Autonomous driving with dynamic skip fire

Abstract

The present invention relates generally to techniques for improving fuel efficiency of a vehicle powered by an internal combustion engine capable of operating at various displacement levels. An autonomous driving unit or cruise controller selects when possible an engine torque output that corresponds to a fuel efficient displacement level. The resultant vehicle speed profile and NVH level is acceptable to vehicle occupants.

What is claimed is: 
     
         1 . An engine control system comprising:
 an engine controller arranged to direct operation of an engine of a vehicle to selectively operate at one of a plurality of different effective displacements; and   an autonomous driving unit configured to determine a requested torque demand based at least partially on sensed operational conditions of the vehicle as provided to the autonomous driving unit, wherein the autonomous driving unit utilizes a collective fuel economy of a plurality of vehicles including the vehicle operating in a platoon to determine a modified torque demand that is different than the requested torque demand,   wherein the engine controller operates the engine to meet the modified torque demand.   
     
     
         2 . The autonomous vehicle as recited in  claim 1 , wherein the collective fuel economy for the modified torque demand is more fuel efficient compared to operating the vehicle at the requested torque demand. 
     
     
         3 . The engine control system as recited in  claim 1 , wherein the autonomous driving unit further utilizes fuel economy information associated with the different effective displacements of the engine. 
     
     
         4 . The engine control system as recited in  claim 1 , wherein the collective fuel economy is chosen or based on one of the following: (a) when the autonomous vehicle is drafting of a lead vehicle; (b) on a local speed limit; (c) travel time between a trip origination point and a trip destination point; or (d) any combination of (a) through (c). 
     
     
         5 . The engine control system as recited in  claim 1 , wherein the modified torque demand provides acceptable NVH characteristics. 
     
     
         6 . The engine control system as recited in  claim 1 , wherein the torque determination utilizes a sensed parameter or information available to the vehicle from an external network including nearby wirelessly connected vehicles and devices capable of providing road, weather, vehicle and traffic data. 
     
     
         7 . The engine control system as recited in  claim 1 , wherein the modified torque demand is based at least in part on the vehicle drafting behind a lead vehicle or is being drafted by a following vehicle. 
     
     
         8 . An autonomous vehicle comprising:
 an internal combustion engine capable of operating at a plurality of displacement levels;   an autonomous driving unit arranged to direct operation of the autonomous vehicle in response to one or more inputs indicative of driving conditions, the autonomous driving unit arranged to ascertain:   (a) a torque request sufficient to meet the driving conditions while operating the autonomous vehicle within a speed range; and   (b) a modified torque request which provides improved fuel economy relative to the ascertained torque request while operating the autonomous vehicle within the speed range; and   an engine controller configured to control the internal combustion engine to operate at a displacement level, selected among the plurality of displacement levels, sufficient to meet the modified torque request, wherein the speed range is based at least in part on the autonomous vehicle drafting of a leading vehicle or being drafted by a following vehicle.   
     
     
         9 . The autonomous vehicle as recited in  claim 8 , wherein a rate of change of the speed range is limited to provide acceptable NVH characteristics. 
     
     
         10 . The autonomous vehicle as recited in  claim 8 , wherein one of the one or more inputs indicative of driving conditions includes a sensed parameter or information available to the vehicle from an external network including a nearby wirelessly connected vehicle. 
     
     
         11 . The autonomous vehicle as recited in  claim 8 , wherein the speed range is chosen or based on one of the following: (a) when the autonomous vehicle drafts a lead vehicle; (b) on a local speed limit; (c) overall travel time between a trip origination point and a trip destination point; or (d) any combination of (a) through (c). 
     
     
         12 . A method comprising:
 directing operation of a vehicle within a speed range using an autonomous driving unit;   operating an internal combustion engine at a plurality of displacement levels, wherein torque generated by the engine propels the vehicle;   operating the engine at a displacement level as dictated by a modified torque request, the modified torque request derived from a torque request derived from sensed driving conditions provided to the autonomous driving unit from an external network,   the modified torque request used to operate the internal combustion engine at the displacement level so that the vehicle operates:   within the speed range; and   with improved fuel efficiency relative to operating the internal combustion engine at another effective displacement level required to meet the torque request derived from the sensed driving conditions.   
     
     
         13 . The method as recited in  claim 12 , wherein the autonomous driving unit utilizes a collective fuel economy of a plurality of vehicles including the vehicle operating in a platoon to determine the modified torque request. 
     
     
         14 . The method as recited in  claim 12 , wherein the modified torque request used to operate the internal combustion engine at the displacement level further operates the vehicle at acceptable levels of NVH with improved fuel efficiency relative to operating the internal combustion engine at the another effective displacement level. 
     
     
         15 . A method of operating an autonomous vehicle, comprising:
 determining a vehicle speed range based on expected driving conditions over a time interval;   determining a plurality of proposed drivetrain torque profiles that propel the vehicle during the time interval within the speed range, wherein at least some of the torque for the plurality of proposed drivetrain torque profiles is provided by an internal combustion engine;   determining fuel efficiency of the internal combustion engine for at least some of the plurality of proposed drivetrain torque profiles;   selecting the proposed drivetrain torque profile that maximizes fuel efficiency as the operating drivetrain torque profile; and   operating the vehicle with the operating drivetrain torque profile.   
     
     
         16 . The method as recited in  claim 15 , wherein determining the vehicle speed range is based on acceptable NVH characteristics. 
     
     
         17 . The method as recited in  claim 15 , wherein determining the plurality of proposed drivetrain torque profiles is based on acceptable NVH characteristics. 
     
     
         18 . The method as recited in  claim 15 , wherein the vehicle speed range is based at least in part on receiving driving condition inputs. 
     
     
         19 . The method as recited in  claim 18 , wherein the receiving includes sensing a parameter or information available to the vehicle from an external network including a nearby wirelessly connected vehicle. 
     
     
         20 . The method as recited in  claim 18  wherein the receiving includes sensing a parameter or information available to the vehicle from a device providing map and sensor data located on the vehicle. 
     
     
         21 . A method as recited in  claim 15  wherein the proposed vehicle speed range is based at least in part on drafting or being drafted by another vehicle. 
     
     
         22 . An engine control system, comprising:
 an engine controller arranged to direct operation of an engine to deliver a requested torque, wherein the engine controller is capable of directing operation of the engine at a plurality of different effective displacements; and   a torque determination unit configured to define and provide the requested torque to the engine controller, the torque determination unit utilizing information either sensed by an autonomous driving unit or received from an external network including nearby wirelessly connected vehicles,   wherein the information is utilized by torque determination unit in defining the requested torque.   
     
     
         23 . The engine control system as recited in  claim 22 , wherein the torque determination unit in cooperation with the autonomous driving unit considers the collective fuel economy of a plurality of vehicles in a platoon when determining the requested torque demand and an operational effective displacement suitable for operating the engine to meet the requested torque demand. 
     
     
         24 . The engine control system as recited in  claim 22  wherein the plurality of different effective displacements corresponds to operating the engine at different skip fire firing fractions respectively, wherein with at least one of the skip fire firing fractions, a particular cylinder is fired during one engine cycle, skipped during the next engine cycle and then selectively skipped or fired during the next engine cycle.