Electricity: motive power systems – Phasing or angular or linear positional control of movable...
Reexamination Certificate
2001-05-02
2003-04-01
Ro, Bentsu (Department: 2837)
Electricity: motive power systems
Phasing or angular or linear positional control of movable...
C318S266000, C318S286000, C318S468000, C318S608000, C388S911000
Reexamination Certificate
active
06541930
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a method for regulating an electric-motor-driven adjusting device, for instance for power windows, a sunroof or the like, and in particular for vehicles with a safety circuit for reversing a drive motor, for example, for the power windows or sunroof, and to an apparatus for performing the method.
An electric-motor-driven adjusting device for automobiles of the type defined at the outset is known, for instance from German Patent DE 33 03 590 C2. In it, a safety circuit is provided which reverses the direction of motion of the window if in its upward motion the window meets some resistance, such as a hand or head of a person.
Often, the occurrence of pinching, i.e. of something being caught when closing an opening, is detected by detecting the motor rpm, which drops if a load occurs. The time required to detect a change in rpm, however, is comparatively long, so that in the event of pinching, injuries or at least pain can occur until the window is finally reversed. To shorten the detection time, it is conceivable to use more-powerful processors in the open-loop control system, but these are expensive.
BRIEF SUMMARY OF THE INVENTION
With this as the point of departure, it is the object of the invention to disclose both a method for regulating an electric-motor-driven adjusting device, especially for vehicles, with a safety circuit for reversing a drive motor of the adjusting device, and an apparatus for performing the method, by which safe and fast detection of pinching is made possible. Furthermore, effects caused for instance by poor pavement or the effects of weather (especially in winter) should not be detected as a pinching situation.
In terms of the method, this object is attained essentially in that an actual value is regulated via a control circuit, in particular a closed-loop control circuit, to a set-point value, the actual value and the set-point value are signals proportional to the rpm or load on the drive motor, and a deviation of the actual value from the set point value is detected with a comparison member of the control circuit and is utilized both to adjust the actual value (motor rpm or load) and to activate the safety circuit.
In this method, the properties of a closed-loop control element are advantageously exploited. The response of an actual closed-loop control element is at its fastest simultaneous with the change at the input. The rate of change and the characteristic at the output are also definable. As part of a control circuit, the controller seeks to regulate a generated control difference or deviation to 0. This deviation serves as a basis for an algorithm for assessing any pinching situations that might occur. Other similar but harmless factors, such as accelerations caused by driving on stretches of bad road, sluggishness of the power window or sunroof system, and properties that are changed by the effect of climate are compensated for by the controller, since they differ from the harmful pinching situations in the characteristic and speed of occurrence. This provision serves to enhance closing safety, for instance when driving on bad roads as noted above. The method is used above all to detect dangerous situations when closing a window or sunroof using an electric-motor-driven drive, to prevent injuries from the pinching forces then operative. Despite the sensitivity of the method to dangerous pinching situations, and the short time available for possible detection, a high degree of closing safety is attained. Acceleration factors from outside, of the kind caused by driving on so-called stretches of bad road do not lead to the detection of a pinching situation and thus to the associated erroneous reversal. Nor is the influence of existing and weather-dictated sluggishness of the system assessed as a pinching situation, and thus the window or sunroof or the like can be closed unimpeded. The method is suited to distinguishing these factors from the dangerous pinching situations.
In an advantageous refinement of the invention, an actual frequency is compared with a set-point frequency, and from the phase deviation between the set-point frequency and the actual frequency, a controlling variable or deviation is derived, by which a safety circuit is activatable.
This embodiment makes use of the fact that every change in frequency results in a change of phase, but the change of phase makes substantially faster detection possible than a change of frequency. It can be appreciated that only the edges corresponding to one another of the frequency signals of the set-point frequency and actual frequency have to be compared with one another in order to obtain a deviation, from which a controlling variable can then be derived.
In a further advantageous concept of the invention, the phase deviation or differential signals are integrated over a predetermined period of time and from the integral the controlling variable or deviation is derived, by which the safety circuit is activatable if a certain threshold value is exceeded. For instance if an obstacle appears in the path of displacement of the window, this makes itself felt in a drop in the motor rpm. The result is a phase deviation between the actual frequency and the set-point frequency. From these differential signals, a controlling variable or deviation is determined. If within a predetermined length of time a plurality of such differential signals then occur, the controlling variable or [standard] deviation passes a certain threshold value, and the system detects an obstacle and reverses the drive motor of the power window. The safety circuit can also be activated by means of a microprocessor and a suitably adapted algorithm.
If periodic loads are exerted on the window because of bumpy roads, change in motor rpm, which in turn can be detected in a phase difference between the set-point frequency and the actual frequency. These phase changes are alternating pulses. However, the integration of these differential signals over a predetermined length of time is essentially 0, so that the threshold value is not passed. As a result, effects caused by bumpy roads are precisely not detected as a pinching situation, and activation of the safety circuit does not ensue.
In a further concept of the invention, a set-point frequency is predetermined by an external set-point frequency transducer and compared with an actual frequency determined by the rpm of the drive motor. The mode of operation of the control circuit is based on a readjustment of the motor rpm, which determines the actual frequency, to the predetermined value of the external set-point frequency.
Alternatively, a set-point frequency determined by the rpm of the drive motor is predetermined. A voltage-controlled oscillator readjusted by the controlling variable or deviation forms a fixed-phase actual frequency. The actual frequency is then returned to the phase detector and compared again with the set-point frequency. If the set-point frequency has changed because of an obstacle in the displacement path, then a phase deviation is detected. In the next cycle, the readjusted voltage-controlled oscillator generates an actual frequency that is fixed in phase with regard to this predetermined set-point frequency.
In terms of the apparatus, the object is essentially attained by a control circuit having a set-point value transducer and an actual value transducer, in which as the set-point value or actual value, a signal proportional to the rpm or load of the drive motor is processed, and having a comparison member for forming a deviation, the deviation being delivered to a detection stage which activates the safety circuit.
An advantageous refinement is formed by a control circuit with a set-point frequency transducer, an actual frequency transducer, and a phase detector, which as a comparator forms a phase difference between the set-point frequency and actual frequency, and with a controller which from the phase difference determines a controlling variable for the control circuit, by which controlli
Boukus, Jr. Charles P.
Kuster Automotive Door Systems GmbH
Ro Bentsu
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