Electricity: motive power systems – With particular motor-driven load device – Power- or motion-transmitting mechanism
Reexamination Certificate
1999-08-25
2002-04-23
Martin, David S. (Department: 2837)
Electricity: motive power systems
With particular motor-driven load device
Power- or motion-transmitting mechanism
C070S271000, C070S275000, C070S276000, C318S653000
Reexamination Certificate
active
06377005
ABSTRACT:
FIELD AND BACKGROUND OF THE INVENTION
The invention relates to a drive device having an actuating drive as well as a position detection device.
U.S. Pat. No. 5,240,296 discloses such a drive device, which in this case is in the form of a locking device for a door of a vehicle, in which case a moving element which is in the form of a lever can be moved to two positions by an actuating drive, and the lever can lock and unlock the locking device.
The position detection device is a potentiometer whose conductor tracks are printed on a printed circuit, in which case these conductor tracks are made contact with by wipers, which are attached to the lever. Depending on the position in which the lever is located, the “locked” or “unlocked” position is detected and, furthermore, the actuating drive is switched on and switched off as a function of the detected position.
The way in which the actuating drive operates and its actuation as well as the detection of the position of the moving element intrinsically works satisfactorily, so that the desired positions can be identified.
However, a major disadvantage in this case is that the position detection device is subjected to severe environmental conditions, such as those which occur in vehicles, and these (the following may be mentioned in this context: temperature fluctuations, moisture, dust and the like) can lead to the position detection device malfunctioning. Furthermore, a position detection device in the form of a potentiometer is subject to wear, which occurs particularly when used in vehicles where the locking device is operated very frequently. In this context, one could consider using appropriate materials which are not subject to such high wear; however, as a rule, these are costly and, in fact, cannot be used for cost reduction in large-scale production.
Furthermore, a position detection device in the form of a potentiometer has the disadvantage that contact resistances can occur at the junction point between the wiper and the conductor track, and these lead to corruption of the indicated position so that, the correct position is not always indicated reliably, even in this case. However, correct indication of position is, in fact, absolutely essential in the application of a locking device since, for example, the actuating drive and thus the entire locking device may be in the “locked” state while the position detection indicates “unlocked” so that the actuating drive would then not be actuated at all, since the position detection device indicates that the actuating drive is already in the “unlocked” position, and it would thus be possible to open the door.
SUMMARY OF THE INVENTION
The invention is thus based on the object of improving the drive device (mentioned initially) having an actuating drive and a position detection device, in such a manner that the described disadvantages are avoided, thus resulting in reliable operation with a very simple formation.
The invention provides that the position detection device has a magnet element which is fitted to the moving element, as well as a Hall element which is arranged in the vicinity of the magnet element, in which case the Hall element is integrated in an electronic module.
The position of the moving element is detected using the physical Hall effect, which is described briefly at the end.
Since the moving element and the position detection device now no longer touch one another, this position detection device operates without making contact and thus without wear, so that, in consequence, the function of the drive device works reliably throughout the entire intrinsic life or throughout the entire life of the object in which it is fitted (for example a vehicle). The design and assembly of the drive device according to the invention are particularly simple, since there is no need for any alignment between the magnet element and the Hall element and sufficiently accurate proximity is adequate to ensure operation of the position detection device. Furthermore, there is no need to fit conductor tracks on the printed circuit or for the presence of wipers and wiper supports of a potentiometer, which actually become particularly complex if it is necessary to monitor the position through a number of revolutions of the moving element.
In a development of the invention, the electronic module is in the form of an ASIC. The term ASIC means an electronic module which has been specified during production or by programming for its application and for the tasks in question. An ASIC includes input and output circuits, memory, processors, monitoring devices (for temperature, voltage, short circuit and the like), sensors (for example the Hall element) and so on. This has the advantage that an integrated module is provided in a very small space. Further advantages include the reduced rest-current consumption, since the only functions which are implemented are those which are required for the respective application, and thus reduced manufacturing costs as well. Testing of an ASIC is likewise simplified, since there is no need to test all the functions of a multifunctional chip which is normally used. One important factor is still very good copying protection, since it is not possible to see from the outside of the ASIC what components it contains and which functions it provides. The integration of the sensor thus provides a so-called active sensor, which provides a signal which has already been evaluated and may have been filtered, for further processing. Signal processing at the detection point also allows sensitive and small measurement variables to be detected, amplified and passed on after evaluation, so that the sensitivity to interference is in consequence reduced. This is particularly important for the application in vehicles since malfunctions are often caused by electromagnetic interference in this case.
In a development of the invention, the electronic module has an evaluation circuit for the output signals of the Hall element and/or an actuation circuit for producing actuation signals for the actuating drive. This increases the compactness of the design since the actuation circuit as well as the evaluation circuit are integrated in the electronic module. It is also advantageous that there is no need for any further wiring, since the electronic module can be arranged with its evaluation circuit and its actuation circuit in the physical vicinity not only of the moving element but also of the actuating drive. This results in a drive device having an integrated actuating drive and an integrated sensor system, in which case the only wiring which need be routed to this drive device is that for the power supply and, possibly, for other signals by means of which the actuating drive is intended to be actuated from the outside.
A further advantage for use of the electronic module within the drive device and for integration of the evaluation circuit and/or of the actuation circuit in the electronic module is that the connection between the evaluation circuit and the Hall element which supplies the output signal as a function of the position, as well as the connection between the actuation circuit and the actuating drive can be kept extremely short, so that there is no need for any measures which would be required to prevent disturbances from radiated interference. This avoids not only the shielding against electromagnetic interference radiation, but also improves the reliability of the overall drive device.
In a development of the invention, the electronic module is arranged on a printed circuit which, in particular, is in the form of a flexible printed circuit, in which case the printed circuit is inserted in a housing of the drive device.
This makes the device very easy to assemble since, on the one hand, the printed circuit can be prefabricated at least together with the electronic modules and, possibly, with further wiring and further modules in a first step, in which case, on the other hand, the moving element, the actuating drive and further functional elements of the drive device can be ins
Mücke Wolfgang
Stalter Reinhard
Zintler Albert
Farber Martin A.
Mannesmann VDO AG
Martin David S.
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