Active accelerator pedal for a vehicle

Abstract

A vehicle includes a drive unit configured to generate a drive torque in driving relationship to wheels of the vehicle, and a gas pedal constructed in the form of an active accelerator pedal which is adjustable over a pedal travel. A control device activates the drive unit in response to a desired torque given by a driver through actuation of the accelerator pedal. Operatively connected to the control device is an actuator which applies a resistance force upon the accelerator pedal, thereby generating a pressure point for the accelerator pedal, with the resistance force increasing in a locally limited pedal travel interval up to a maximum force which can be overridden by the driver. An evaluation unit of the control unit generates a deactivation signal within the pedal travel interval, when the accelerator pedal reaches a predefined limit hold time.

Claims

1. A vehicle, comprising: a drive unit configured to generate a drive torque in driving relationship to wheels of the vehicle; a gas pedal constructed in the form of an active accelerator pedal which is adjustable over a pedal travel; a control device configured to activate the drive unit in response to a desired torque given by a driver through actuation of the accelerator pedal, said control device including an evaluation unit; and an actuator operatively connected to the control unit and configured to apply a resistance force upon the accelerator pedal, thereby generating a pressure point for the accelerator pedal, with the resistance force increasing in a locally limited pedal travel interval up to a maximum force which can be overridden by the driver, said evaluation unit being configured to generate a deactivation signal within the pedal travel interval, when the accelerator pedal reaches a predefined limit hold time to thereby enable a decrease of the resistance force.

2. The vehicle of claim 1, wherein the evaluation unit is configured to ascertain an actual hold time of the accelerator pedal, as actuated by the driver, in a pedal position within the pedal travel interval, to compare the ascertained actual hold time with the limit hold time, and to decrease the resistance force, when the limit hold time is exceeded.

3. The vehicle of claim 1, wherein the actuator is deactivated in the presence of the deactivation signal.

4. The vehicle of claim 1, wherein the evaluation unit is configured to recognize, when the predefined limit hold time is reached, that a pedal position of the accelerator pedal within the pedal travel interval is to be retained, and to deactivate the actuator.

5. The vehicle of claim 1, wherein the presence of the pressure point provides a haptic feedback about a travel mode.

6. The vehicle of claim 5, wherein the drive unit is configured for operation in a first operating mode and a second operating mode, with a change from the first operating mode to the second operating mode being signaled to the driver when overriding the pressure point.

7. The vehicle of claim 6, wherein the drive unit includes an internal combustion engine and at least one electric machine, with the first operating mode being implemented solely through operation of the electric machine, and the second operating mode being implemented through addition of the internal combustion engine or sole operation of the internal combustion engine.

8. The vehicle of claim 1, wherein the actuator is activated to abruptly apply the resistance force in the event the driver again actuates the accelerator pedal during continuous travel with a positive gradient.

9. An active accelerator pedal for a vehicle, said active accelerator pedal being adjustable over a pedal travel and constructed for actuation by a driver to generate a predefined desired torque transmitted to a control unit which actuates a drive unit in response to the defined desired torque, with a resistance force being imposed on the active accelerator pedal from an actuator operatively connected to the control unit to thereby generate a pressure point for the accelerator pedal, with the resistance force increasing in a locally limited pedal travel interval up to a maximum force which can be overridden by the driver, wherein a deactivation signal within the pedal travel interval is generated by an evaluation unit of the control unit, when the accelerator pedal reaches a predefined limit hold time to thereby enable a decrease of the resistance force.

10. A method, comprising: depressing by a driver an active accelerator pedal to generate a desired torque; transmitting the desired torque to a control unit for operating a drive unit in response to the desired torque; imposing a resistance force on the active accelerator pedal from an actuator operatively connected to the control unit, thereby generating a pressure point for the accelerator pedal, with the resistance force increasing in a locally limited pedal travel interval up to a maximum force which can be overridden by the driver; and generating a deactivation signal within the pedal travel interval, when the accelerator pedal reaches a predefined limit hold time to thereby enable a decrease of the resistance force.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) Other features and advantages of the present invention will be more readily apparent upon reading the following description of currently preferred exemplified embodiments of the invention with reference to the accompanying drawing, in which:

(2) FIG. 1 is a roughly schematic block diagram of a dive train of a motor vehicle with associated control for an active accelerator pedal in accordance with the present invention;

(3) FIG. 2 is an accelerator pedal characteristic curve, showing the relation between pedal position and resistance force; and

(4) FIGS. 3 and 4 are accelerator pedal characteristic curves corresponding to FIG. 2 to illustrate a control strategy in accordance with the present invention for controlling an actuator of the accelerator pedal.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

(5) Throughout all the figures, same or corresponding elements may generally be indicated by same reference numerals. These depicted embodiments are to be understood as illustrative of the invention and not as limiting in any way. It should also be understood that the figures are not necessarily to scale and that the embodiments may be illustrated by graphic symbols, phantom lines, diagrammatic representations and fragmentary views. In certain instances, details which are not necessary for an understanding of the present invention or which render other details difficult to perceive may have been omitted.

(6) Turning now to the drawing, and in particular to FIG. 1, there is shown a roughly schematic block diagram of a dive train of a motor vehicle with associated control for the drive unit in accordance with the present invention. For ease of understanding of the present invention, the block diagram is only a rough representation and does not reflect an accurate structure of the motor vehicle. The drive unit of the motor vehicle includes an internal combustion engine 1 and an electric machine 3 connected in series in the drive train and coupled in the drive train in driving relation with a transmission 5. The transmission 5 is in driving relation with a front-side axle differential 6 which is in driving relation with a rear axle differential 9. The internal combustion engine 1 and the electric motor 3 can be operated via a motor controller 11 and a power electronics 13 by means of an electronic control device 15 which ascertains a plurality of travel parameters as input variables. Moreover, the control device 15 is linked via signal connection with a gas pedal 17 which is configured as an active accelerator pedal or so-called force-feedback pedal having a characteristic curve (FIG. 2) which is variable in dependence on control signals of the control device 15. For this purpose, the control device 15 is connected with the accelerator pedal 17 via signal line 21. Depending on the angle of displacement (i.e. the pedal travel s) of the active accelerator pedal 17, a driver input, representative of a desired drive torque M.sub.desired, is fed to the control device 15. The control device 15 controls in response to the desired torque input the engine controller 11 and/or the power electronics 13 via signal lines 19.

(7) FIG. 1 indicates the accelerator pedal 17 as being adjustable between a rest position S.sub.R and a fully depressed position S.sub.max (FIGS. 2 to 4). The accelerator pedal 17 is acted upon by a return spring element 23 with a recoiling force F.sub.R in a direction of the rest position S.sub.R. An actuator 25 can apply a resistance force F.sub.G upon the active accelerator pedal 17, thereby generating a pressure point A (FIGS. 2 to 4) in the characteristic curve of the accelerator pedal 17. The pressure point A is generated as the resistance force F.sub.G rises in FIG. 2 in a locally limited pedal travel interval S up to a maximum force F.sub.G, max, which can be overridden by the driver's foot, i.e. the driver can still push through.

(8) In the non-limiting embodiment shown here, the accelerator pedal 17 is incorporated, by way of example, in a hybrid vehicle, which may be configured such as to be powered in a first operating mode SI solely by the electric machine 3, and in a second operating mode SII solely by the internal combustion engine 1. The pressure point A provides a haptic feedback to the driver to prompt the driver that the hybrid vehicle changes from the first operating mode SI to the second operating mode SII, when the pressure point A is overridden. The pressure point A can be shifted in dependence on diverse travel parameters, e.g. loading state of a traction battery (not shown), along the pedal characteristic curve between the pedal rest position S.sub.R and the depressed pedal position S.sub.max.

(9) The actuator 25 can be activated/deactivated by an accelerator pedal control unit 27 which is operatively connected to an evaluation unit 29. the evaluation unit 29 ascertains during travel an actual hold time t.sub.actual in which the driver maintains the accelerator pedal 17 in a pedal position S.sub.1 within the pedal travel interval S (FIG. 3).

(10) The evaluation unit 29 and the control unit 27 operate the actuator 25 of the accelerator pedal 17 with a control strategy that is energy saving and applicable in particular in the following travel situation: The driver intends to power the vehicle solely via the electric machine 1. For this purpose, the driver's foot activates the pressure point A, for example in a position-controlled or force-controlled manner, without exceeding it. This is shown in FIG. 3, depicting an actual pedal position S.sub.1 which is chosen by the driver via a force-controlled activation for example, and in which the foot actuation force F.sub.B applied by the driver and the pedal recoiling force F.sub.R and the pedal resistance force F.sub.G are at an equilibrium of forces.

(11) The actual pedal position S.sub.1, indicated in FIGS. 3 and 4 by a cross is located directly at the pressure point A, specifically within the afore-defined pedal travel interval S which is located anteriorly of the pressure point A. The evaluation unit 29 ascertains the actual hold time t.sub.actual of the accelerator pedal 17 in its pedal position S.sub.1 in the pedal travel interval S. The evaluation unit 29 compares the ascertained actual hold time t.sub.actual with a limit hold time t.sub.G, stored in the evaluation unit 29. When the actual hold time t.sub.actual exceeds the limit hold time t.sub.G, the evaluation unit 29 recognizes then that the driver intends to retain the pedal position S.sub.1 in the pedal travel interval S, without pushing through the pressure point A.

(12) As a result, the evaluation unit 29 generates a deactivation signal S.sub.OFF. In the presence of the deactivation signal S.sub.OFF, the control unit 27 deactivates the actuator 25 so that the resistance force F.sub.G defining the pressure point A is removed, as indicated by the diagram of FIG. 4.

(13) While the invention has been illustrated and described in connection with currently preferred embodiments shown and described in detail, it is not intended to be limited to the details shown since various modifications and structural changes may be made without departing in any way from the spirit and scope of the present invention. The embodiments were chosen and described in order to explain the principles of the invention and practical application to thereby enable a person skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated.