Method for providing a pressure point for a haptic gas pedal of a hybrid vehicle

Abstract

A system and method for controlling a hybrid vehicle having an electric operating mode selectively modify a pressure point for an accelerator pedal in response to current vehicle and/or ambient operating conditions to reduce unintentional starting of an internal combustion engine and maintain electric mode operation while the accelerator pedal position is less than the pressure point. The vehicle operating conditions or mode may indicate a parking maneuver, stop-and-go traffic, or an eco mode where electric operation may be desired.

Claims

1. A method for operating a hybrid vehicle, comprising: operating the vehicle with an exclusively electric drive when accelerator pedal travel is less than a pressure point or until a battery state of charge requires starting an engine, the pressure point associated with increased force for further pedal travel and set in response to both the battery state of charge being above a threshold and operating conditions satisfying a predefined application case including the vehicle being located in a speed zone having a speed limit below a predetermined threshold as determined by a traffic sign sensor wherein the operating conditions comprise activation of a vehicle park assist system.

2. The method of claim 1 wherein the pressure point is set for a predetermined time period and then removed after the predetermined time period.

3. The method of claim 1 wherein the pressure point has an associated operating force progression as a function of accelerator pedal travel relative to the pressure point.

4. The method of claim 3 wherein the associated operating force progression begins at an initial pressure point and operating force increases to at least the pressure point.

5. The method of claim 1 wherein parameters associated with the pressure point are set in response to operating conditions satisfying the application case, wherein the parameters comprise a slope of accelerator pedal force as a function of accelerator pedal travel or accelerator pedal angle.

6. The method of claim 1 wherein parameters associated with the pressure point are set in response to the operating conditions satisfying the application case, wherein the parameters comprise an accelerator pedal position start point and end point of increased operating force progression surrounding the pressure point.

7. The method of claim 6 wherein parameters associated with the pressure point are set in response to the operating conditions satisfying the application case, wherein the parameters comprise a force difference between the start point and the end point of the increased operating force progression.

8. The method of claim 1 wherein the engine is started only after accelerator pedal position exceeds the pressure point.

9. The method of claim 1 wherein the operating conditions further comprise activation of an energy-saving mode switch.

10. A hybrid vehicle having a haptic accelerator pedal with a controllable force profile, comprising: a controller coupled to the haptic accelerator pedal and programmed to operate the vehicle in an electric mode when accelerator pedal position is less than a selectable pressure point associated with increased force for further accelerator pedal travel, the pressure point being varied in response to a traction battery state of charge and vehicle speed being below an associated threshold and wherein the pressure point is varied in response to activation of a vehicle parking assist feature.

11. The hybrid vehicle of claim 10 wherein the controller is programmed to set the pressure point for a predetermined time period and to remove the pressure point thereafter.

12. The hybrid vehicle of claim 10 wherein the pressure point is varied in response to activation of a vehicle economy mode switch.

13. A method for operating a hybrid vehicle, comprising: setting, by a controller, an accelerator pedal force profile having a pressure point associated with increased force for accelerator pedal position beyond the pressure point, wherein the pressure point is set responsive to activation of a vehicle parking assist mode; and operating the vehicle in an electric drive mode unless accelerator pedal position exceeds the pressure point or battery state of charge is below an associated threshold.

14. The method of claim 13 further comprising starting an engine in response to accelerator pedal position exceeding the pressure point.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 schematically shows a flow chart illustrating operation of a system or method for modifying accelerator force progression according to various embodiments;

(2) FIG. 2 shows, by way of example, a force progression of the operating force of the gas or accelerator pedal F as a function of the pedal travel s or the pedal angle .

DETAILED DESCRIPTION

(3) As required, detailed embodiments are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary and may be embodied in various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the claimed subject matter based on the disclosed representative embodiments.

(4) FIG. 1 shows one possible flow chart for utilizing a system or method according to embodiments of the disclosure.

(5) First, a plurality of application cases i, e.g., four application cases i=1 through i=4 are predefined with respect to their criteria. These application cases i represent driving profiles, which make it appear desirable to implement these driving profiles preferably in the purely electric operation of a hybrid vehicle or a mild hybrid vehicle.

(6) Such application cases can be, for example: 1. The vehicle is located in a slow speed zone, for example, on a residential street or in a zone having speed limits up to 30 km/h or 50 km/h. 2. A driving situation with slow-moving traffic or a traffic jam exists. 3. The park assist system is activated, and so it can be assumed that a maneuver into a parking space or out of a parking space is taking place. 4. The vehicle, with respect to its basic setting, is in an energy-saving mode, for example due to a corresponding selection of an energy-saving configuration carried out by the vehicle driver.

(7) Further application cases are also conceivable, of course, which make it appear desirable to allow the resultant driving profiles to operate purely electrically.

(8) If it is now determined that the vehicle is in an operating situation in which one of the predefined application cases exists, a check is subsequently carried out to determine whether the current operating state of the vehicle is suitable for implementing the driving profile belonging to the detected application case, in purely electric operation. Such a parameter for the operating state of the vehicle can be, for example, the state of charge of the energy storage device(s).

(9) If the result of the check of the operating state of the vehicle is that the operating state of the vehicle is sufficient for a purely electric operation of the vehicle during the present application case, then, according to various embodiments, a pressure point is set at a point s.sub.3 of the gas pedal travel of the gas pedal. This pressure point is characterized by an operating force F.sub.2.sup.i which is elevated as compared to the progression of the gas pedal operating force without a pressure point. Such a pressure point [s.sub.3.sup.i; F.sub.2.sup.i] is preferably set for a certain time period t. During this time period t, the vehicle is operated purely electrically, provided the vehicle operator does not intentionally overcome the pressure point by applying an operating force which is greater than the force F.sub.2.sup.i at the pressure point [s.sub.3.sup.i; F.sub.2.sup.i].

(10) If the result of the check is that the operating state of the vehicle is insufficient for handling the application case purely electrically, setting the pressure point can be dispensed with and the vehicle can be operated by activating the internal combustion engine and implementing the driving profile in the purely internal combustion-driven mode. Alternatively, a combined operation of electric drive and internal combustion engine-drive can take place.

(11) In FIG. 2, a progression of an operating force F as a function of a gas pedal travel s or a gas pedal angle is shown by way of example. The operating force progression F(s; ) as a function of the gas pedal travel s or the gas pedal angle is shown for the entire gas pedal travel s/ from an unactuated position s=s.sub.0 of the gas pedal up to the point when the gas pedal is depressed down to an end stop ES. A force maximum is present at one point s.sub.3.sup.i. The operating force at the point s.sub.3.sup.i is F.sub.2.sup.i. At this point, the driver of the vehicle perceives a pressure point [s.sub.3.sup.i; F.sub.2.sup.i] at the gas pedal. A pressure point progression is illustrated in the vicinity of the pressure point [s.sub.3.sup.i; F.sub.2.sup.i]. This pressure point progression is represented by a solid line above a dotted line F.sub.s. The dotted line F.sub.s shows a standard operating force progression F.sub.s as a function of the pedal travel s when a pressure point has not been predetermined. At a point [s.sub.1.sup.i; F.sub.1.sup.i], which is considered to be the start point for the pressure point progression F(s; ), the operating force F increases above the standard operating force F.sub.s.

(12) At a point s.sub.2.sup.i there is an end point [s.sub.2.sup.i; F.sub.3.sup.i] of the pressure point progression F(s; ). Between the start point [s.sub.1.sup.i; F.sub.1.sup.i] and the end point [s.sub.2.sup.i; F.sub.3.sup.i] of the pressure point progression, there is an operating force which is elevated relative to the standardized operating force F.sub.s, wherein an operating force maximum exists at the point s.sub.3.sup.i, which forms the pressure point [s.sub.3.sup.i; F.sub.2.sup.i].

(13) A distance s.sup.i.sub.12 between the start point [s.sub.1.sup.i; F.sub.1.sup.i] and the end point [s.sub.2.sup.i; F.sub.3.sup.i] of the pressure point progression F(s; ) can be freely determined within wide limits. Likewise, the increase, i.e., the gradient of the operating force F between the start point [s.sub.1.sup.i; F.sub.1.sup.i] and the pressure point [s.sub.3.sup.i; F.sub.2.sup.i], can be adjusted depending on the point s.sub.3.sup.i at which the pressure point [s.sub.3.sup.i; F.sub.2.sup.i] is intended to be located. In a range of the gas pedal operating force progression which is still flat, i.e., in a range close to the unactuated pedal position F.sub.0/s.sub.0, for example, even a lesser gradient can be perceived as a clear increase of the operating force F toward a pressure point [s.sub.3.sup.i; F.sub.2.sup.i]. The closer the operating point [s.sub.3.sup.i; F.sub.2.sup.i] is intended to be to the end stop ES of the pedal, the steeper the operating force increase should be starting at the start point [s.sub.1.sup.i; F.sub.1.sup.i] up to the pressure point [s.sub.3.sup.i; F.sub.2.sup.i], so that the driver receives distinct haptic feedback that a pressure point [s.sub.3.sup.i; F.sub.2.sup.i] should exist here.

(14) Likewise, force differences F.sub.I.sup.i and F.sub.II.sup.i can be established within wide limits, wherein the force difference F.sub.1.sup.i is a force difference between the pedal force at the pressure point [s.sub.3.sup.i; F.sub.2.sup.i] and the start point [s.sub.1.sup.i; F.sub.1.sup.i], and the force difference F.sub.II.sup.i is a force difference between the force at the pressure point [s.sub.3.sup.i; F.sub.2.sup.i] and at the end point [s.sub.2.sup.i; F.sub.3.sup.i].

(15) The extent to which these parameters are selected with respect to their magnitude and position depends essentially on the type of application case and on the subjective perception regarding the point at which a distinct pressure point [s.sub.3.sup.i; F.sub.2.sup.i] should be noticed. Suitable forces can be determined using empirical test series. It can also be advantageous, if necessary, to provide force differences F.sub.I.sup.i and/or F.sub.II.sup.i which differ for different application cases. Therefore, for example, a very high force difference F.sub.I.sup.i can result in a pressure point which is very difficult to overcome, and so the driver, with approximately 100% certainty, will not unintentionally overcome this pressure point and induce an unintentional activation of the internal combustion engine. Such a high value of the force difference can be useful, for example, when the vehicle is being parked. It can also be useful, however, in another application case, for example, driving in a slow speed zone, to set the force difference F.sub.I.sup.i to be slightly lower, so that the pressure point [s.sub.3.sup.i; F.sub.2.sup.i] is indeed distinctly noticeable but is also more easily overcome. In this case, values which can be selected within relatively wide ranges can yield meaningful results.

(16) By way of the present disclosure, given a suitable operating state of a vehicle and the presence of a certain application case i, i.e., a certain existing driving profile, an unintentional activation of the internal combustion engine and associated inconveniences or undesirable effects are successfully avoided or are at least greatly reduced.

(17) While representative embodiments are described above, it is not intended that these embodiments describe all possible forms of the claimed subject matter. The words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the disclosure. Additionally, the features of various implementing embodiments may be combined to form further embodiments that may not be explicitly described or illustrated.