Patent Application
20130158829
The present disclosure relates to automotive vehicles, and more particularly to fuel economy for automotive vehicles.
Automotive vehicles utilize cruise control systems to assist vehicle operators in maintaining vehicles at a constant speed when traveling long distances. Operation of the vehicle in cruise control mode may increase fuel economy over long distances. As is known, the vehicle operator can engage and disengaged the cruise control systems as desired. Vehicle speed is typically maintained at a constant speed over differing road terrains. However, as is known, operation of the cruise control system may be terminated by application of the brakes by the vehicle operator.
Recently adaptive cruise control (ACC) systems have been developed. ACC systems adjust the speed of the vehicle to accommodate changes in traffic speed when operating in cruise control mode. Typically, ACC systems maintain a desired distance from a forward vehicle. If the forward vehicle changes speeds or changes lanes the ACC system will return the vehicle to the cruising speed originally set by the vehicle operator. As with standard cruise control systems, the ACC systems may be terminated by application of the vehicle brakes.
The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
A method of operating a cruise control system for a vehicle comprises selecting a fuel economy mode for the cruise control system and determining a desired fuel economy. A fuel economy level of the vehicle is maintained at the desired fuel economy when operating in fuel economy mode.
A method of operating a vehicle comprises selecting an operating mode for a cruise control system. At least one of a desired fuel economy and an initial cruise control speed for the vehicle are determined. A fuel supply to an engine for the vehicle is adjusted with an engine controller in communication with a fuel supply system to maintain a fuel economy level of the vehicle at the desired fuel economy when operating in a fuel economy mode.
Further areas of applicability of the present disclosure will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the disclosure, are intended for purposes of illustration only and are not intended to limit the scope of the disclosure.
The present disclosure will become more fully understood from the detailed description and the accompanying drawings, wherein:
The following description is merely exemplary in nature and is in no way intended to limit the disclosure, its application, or uses. For purposes of clarity, the same reference numbers will be used in the drawings to identify similar elements.
In another embodiment, in a standard operating mode the cruise control system 12 maintains the speed of the vehicle 10 at the speed selected by the driver. If the cruise control system 12 is an ACC system the cruise control system 12 will adjust the speed of the vehicle 10 to maintain a predetermined distance from forward objects. In the standard operating mode the cruise control system 12 maintains the vehicle 10 at the selected speed regardless of the terrain and contours of the road and only adjusts the vehicle speed 10 based upon intervening objects as mentioned above. The speed of the vehicle 10 is typically maintained within a range of the preselected speed by an engine controller 16. The vehicle 10 speed is maintain even when encountering changes in the slope of the road, such as when ascending or descending a hill. The engine controller 16 cooperates with a fuel supply system 18 to adjust the fuel supply as required to maintain the vehicle 10 at the preselected speed.
The fuel economy mode 14 may be selected by the vehicle operator using the control device 24. In the fuel economy mode 14, the speed of the vehicle 10 may be allowed to vary while the cruise control system 12 operates to maintain a desired fuel economy. The desired fuel economy may correspond to the fuel economy level for the vehicle 10 at a pre-selected speed when traveling along a flat surface. The desired fuel economy of the vehicle 10 can be determined by the fuel economy level that is calculated when the fuel economy mode 14 of the cruise control system 12 is initiated. Thereafter, the vehicle 10 will maintain the desired fuel economy regardless of the changes in the road. Again the engine controller 16 and the fuel supply system 18 cooperate with the cruise control system 12 to operate the vehicle 10 in a manner that maintains the fuel economy as the desired fuel economy level.
A high fuel economy level is generally desirable. Therefore, maintaining the vehicle 10 at the desired fuel economy may mean allowing the fuel economy of the vehicle 10 to increase, but not allowing the fuel economy to decrease below the desired level. Alternatively, the fuel economy level may also be limited from increasing. For example, due to terrain an increase in the fuel economy level may also correspond to an increase in speed of the vehicle 10, e.g. when the vehicle 10 is travelling downhill. In order to maintain the vehicle 10 at safe operating speed the fuel economy level may be maintained at the pre-selected level and not allowed to increase outside of a predetermined range, thus, restricting the speed of the vehicle 10. In this instance, an increase in the fuel economy level would be allowable as long as the vehicle 10 is travelling within safe operating speeds.
An example of the vehicle 10 operating in the fuel economy mode 14 is illustrated in
When the vehicle 10 descends the other side of the hill, illustrated by vehicle 10A in
In the fuel economy mode 14 the engine controller 16 cooperates with the fuel system 18 to only provide the amount of fuel necessary for the desired fuel economy. Therefore, the vehicle 10 will slow while ascending the hill and regain speed when descending the hill such that, the overall speed of the vehicle 10 after the hill will be approximately the same speed as before the hill while the fuel economy of the vehicle 10 is maintained above the desired fuel economy level.
The desired fuel economy level may be adjusted by the vehicle 10 operator through the use of the control device 24. For example, the fuel economy may be increased or decreased in an incremental manner. The adjustment of the desired fuel economy level may be similar to adjusting a preselected speed of the vehicle 10 when operating in the standard operating mode of the cruise control system 12
In fuel economy mode 14 the fuel economy level may be adjusted under selected conditions. For example, if the cruise control system 12 is an ACC system the vehicle 10 may be operated at another fuel economy level to maintain a desired distance between the vehicle 10 and a forward object. Once the forward object is no longer in the path of the vehicle 10 the cruise control system 12 may return operation to the desired fuel economy level 14.
In fuel economy mode 14 the fuel economy of the vehicle 10 is maintained above the desired level while speed of the vehicle 10 is allowed to vary, step 28. However, this may be inconvenient to the driver on a steep incline when the vehicle 10 will slow more than is preferred to maintain the desired fuel economy level. Thus, the cruise control system 12 may be arranged to operate at a desired fuel economy level, with a predetermined speed range. In this instance, the vehicle 10 will maintain the desired fuel economy level, step 28. However, the cruise control system 12 will also monitor the vehicle 10 speed, step 30. If the vehicle 10 speed drops below a predetermined level the cruise control system 12 may temporarily adjust the fuel economy level to operate the vehicle 10 at a minimum determined speed, step 32. The vehicle 10 will return to operating at the desired fuel economy level once the vehicle 10 is able to maintain the minimum determined speed with the original desired fuel economy, step 34.
In this embodiment, when the cruise control system 12 is in fuel economy mode 14 the desired fuel economy may be maintained as long as the vehicle 10 is within a predetermined range of the speed at the time the fuel economy mode 14 was initiated by the driver. When the predetermined range is exceeded the fuel economy supplied by the vehicle 10 may be adjusted to maintain the vehicle within the predetermined speed range, until the vehicle 10 speed can be maintained without requiring adjustment from the desired fuel economy. At that time the fuel economy mode 14 will continue operation at the desired fuel economy level, i.e. at the fuel economy level that was selected when the fuel economy mode 14 was initiated.
For example, if the vehicle 10 was traveling at 60 mph when the fuel economy mode 14 was initiated the cruise control system 12 will maintain the vehicle 10 at the selected fuel economy level as long as the vehicle 10 speed is within a predetermined range of the initial vehicle speed, e.g. within 10 mph of the original speed of 60 mph. If the vehicle 10 departs the predetermined range the fuel economy level of the vehicle 10 will be adjusted to maintain the closest limit of the predetermined range. That is, if the vehicle 10 begins to slow down below 50 mph the fuel economy will be adjusted to maintain the vehicle speed at 50 mph. At such time that the vehicle 10 is able to stay within the predetermined range without the adjusted fuel economy level, the cruise control system 12 will return to maintaining the fuel economy for the vehicle at the initial fuel economy level.
As mentioned above, while an increase in fuel economy is desirable it the fuel economy level may be limited from increase to maintain the vehicle within safe operating speeds. Thus, the vehicle speed may be limited by the fuel economy mode 14 of the cruise control system 12 without requiring braking action to slow the vehicle 10.
While the best modes for carrying out the invention have been described in detail the true scope of the disclosure should not be so limited, since those familiar with the art to which this invention relates will recognize various alternative designs and embodiments for practicing the invention within the scope of the appended claims.
