System and method of blockage detection during an automatic adjustment of a movable vehicle part in a motor vehicle

Abstract

A system and method are provided for detecting blockages during an automatic adjustment of a movable vehicle part in a motor vehicle equipped with an electric motor drive and an electronic control unit. The drive current as well as the movement speed of the drive are detected by the electronic control unit. When the movement speed increases above the normal level, the control unit suppresses the detection of a blockage event if a drive current increase required for the movement speed increase cannot be ascertained.

Claims

1. A system for detecting blockages during an automatic adjustment of a movable vehicle part in a motor vehicle, comprising: an electric motor drive configured to move the movable vehicle part in the motor vehicle; an electronic control unit in communication with the electric-motor drive, wherein the electronic control unit detects a drive current and a movement speed of the electric motor drive, and the electronic control unit is configured to first determine whether the detected drive current corresponds to a given drive current that is required to achieve the detected movement speed of the electric motor drive, and the electronic control unit is configured to then determine whether or not a blockage exists based on a result of the first determination, wherein the electronic control unit prevents detection of a blockage when the movement speed increases above a given value but an associated increase of the drive current for the increased movement speed is not detected.

2. The system according to claim 1, wherein the electronic control unit continues to prevent the detection of a blockage during a predefined time period or a predefined travel amount following the movement speed increase above the given value, if a drop of the movement speed is detected with a simultaneous increase of the drive current, wherein a maximum amount of the predefined time period or the predefined travel amount occurs either when the movable vehicle part has reached its fully open or fully closed position.

3. The system according to claim 2, wherein after the expiration of the predefined time period or the predefined travel amount, the electronic control unit continues to permit an increase of the movement speed above the already increased movement speed without detecting the blockage if the drive current continues to not rise correspondingly.

4. A method of operating a blockage detection system during an automatic adjustment of a movable vehicle part in a motor vehicle, the motor vehicle being equipped with an electric-motor drive for the movable vehicle part and an electronic control unit coupled with the electric-motor drive, the method comprising the acts of: detecting a drive current and a movement speed of the electric motor drive, via the electronic control unit, during the automatic adjustment of the movable vehicle part in the motor vehicle; first determining whether the detected drive current corresponds to a given drive current that is required to achieve the detected movement speed of the electric motor drive; and then determining whether or not a blockage exists based on a result of the first determination, further comprising the acts of: detecting, via the electronic control unit, an increase of the movement speed above a given value, which detection normally triggers a detection of a blockage event; and preventing, via the electronic control unit, the detection of the blockage event when the movement speed increases above the given value but a corresponding increase of the drive current for the increased movement speed is not detected.

5. The method according to claim 4, further comprising the act of: continuing to prevent the detection of the blockage event when, during a predefined time period or predefined travel of the movable vehicle part, a drop of movement speed is detected with a simultaneous increase of the drive current in a case in which the movement speed increased above the given value before the predefined time period or before the predefined travel of the movable vehicle part, and, a maximum amount of the predefined time period or a predefined travel amount occurs either when the movable vehicle part has reached its fully open or fully closed position.

6. The method according to claim 5, further comprising the act of: after the expiration of the predefined time period or the predefined travel of the movable vehicle part, the electronic control unit continues to permit an increase of the movement speed above the already increased movement speed without detecting a blockage event if the drive current continues to not rise correspondingly.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic representation of the components and signals relevant to the invention in the exemplary case where a tailgate is the movable vehicle part; and

(2) FIGS. 2a, 2b and 2c are each a schematic representation of the signal forms to essentially be observed for the invention.

DETAILED DESCRIPTION OF THE DRAWINGS

(3) FIG. 1 is a side view illustrating the rear half of a vehicle 1 with an automatically adjustable tailgate 2 and an electric motor drive 3 in the form of an electric motor (here, a spindle motor). The electric motor 3 is triggered by way of a drive current I.

(4) The desired value of the drive current I is automatically controlled by an electronic control unit 4. The actual value of the drive current I is detected and evaluated by the control unit 4. Furthermore, the movement speed of the tailgate 2 is detected and evaluated in the control unit 4 by way of the rotational speed n of the electric motor 3.

(5) The control unit 4 contains a correspondingly programmed software module (not shown here in detail), by which, in the event of an increase dn.sub.1/dt of the rotational speed or movement speed n occurring above the normal level dn.sub.0/dt, the detection of a blocking event is suppressed when a rise dI.sub.1/dt of the drive current I required for this increase dn.sub.1/dt of the movement speed n cannot be determined. In the following, an example will be explained in detail by reference to FIGS. 2a to 2c:

(6) In FIG. 2a, the rotational speed n is illustrated over the time t. First, an exclusively automatic closing operation of the tailgate 2 is carried out (broken line in FIG. 1). The rotational speed increases with a normal level being dn.sub.0/dt. At the point in time t1, the closing operation is assisted by a manually implemented additional force F on the tailgate 2. As a result, the rotational speed n increases with a gradient dn.sub.1/dt occurring above the normal level dn.sub.0/dt. FIG. 2c illustrates that, for this increase dn.sub.1/dt of the movement speed n, a rise dI.sub.1/dt of the drive current I would be required (illustrated by a broken line) which, however, could in fact not be determined (solid line) in this embodiment according to FIG. 2b at the point in time t1. The drive current I may even slightly drop starting from the point in time t1 as a result of the manual assistance. The detection of a blockage event is therefore correctly suppressed and the tailgate 2 continues to be closed automatically.

(7) When the force F is removed again at the point in time t2 and the manual assistance in the closing direction is therefore terminated, this will result in a rotational speed drop ?dn.sub.2/dt. In a further aspect of the invention, the detection of the blockage event now continues to be suppressed when, after or during a predefined time period Dt (or a predefined travel), starting with the occurrence of the increase dn.sub.1/dt, the drop ?dn.sub.2/dt of the rotational speed n is detected with the simultaneous rise dI.sub.2/dt of the drive current I.

(8) Therefore, in principle, no blockage event is detected in the case of a course of the drive current I according to FIG. 2b.

(9) In a further preferred development of the invention, after the expiration of a predefined time or of a predefined travel of the movable vehicle part 2, starting with the suppression of the detection of a blockage event, the control unit 4 will continue to permit an increasing of the movement speed n above the already raised increase dn.sub.1/dt without detecting a blockage event, if the drive current I continues to not rise correspondingly.

(10) The invention can naturally be used not only for the closing operation but in the same manner for the opening operation with manual assistance in the opening direction.

(11) The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.