Electricity: motive power systems – Motor-reversing – Automatic and/or with time-delay means
Reexamination Certificate
2002-02-21
2003-12-23
Ro, Bentsu (Department: 2837)
Electricity: motive power systems
Motor-reversing
Automatic and/or with time-delay means
C318S433000, C318S434000, C318S463000
Reexamination Certificate
active
06667590
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a power window apparatus with a function to detect a foreign object caught in the window, and particularly to a power window apparatus which shortens the non-detection time in the motor startup period and can detect an object caught in the window even during the motor startup period.
2. Description of Related Art
A conventional car power window apparatus with a function to detect a foreign object is known where, if it detects a foreign object caught in a window during a manual or automatic closing operation of the window, it stops the movement of the window immediately or moves the window in the window opening direction.
The conventional power window apparatus uses motor load current values as parameters for detection of a foreign object caught in the window (this type of apparatus is hereinafter called a “load current based type”). In this apparatus, the whole window moving range is divided into multiple moving subdivisions and a reference current value indicating whether a foreign subject is caught in the window or not is preset for each moving subdivision; as the window moves through each of these subdivisions, the motor load current value detected in the subdivision is compared with the reference current value preset for that subdivision and if, as a result of comparison, the motor load current value is found to considerably exceed the reference current value, the apparatus concludes that a foreign object has been caught in the window and immediately stops the movement of the window or moves the window in the window opening direction.
In this power window apparatus, reference current values to be preset for the multiple moving subdivisions are determined as follows: as the window moves through the subdivisions, the peak motor load current for each of such subdivisions is measured in the condition that nothing is caught in the window. The reference current value for a subdivision is thus determined according to the measured peak current value for that subdivision.
Among known power window apparatuses capable of detecting a foreign object, there is a type which uses motor load torques as parameters for foreign object detection instead of motor load current values (this is hereinafter called a load torque based type.).
In the load current based type of power window apparatus or the load torque based type of power window apparatus, when the motor for opening/closing the window is started, initially the load current which flows through the motor transitionally fluctuates or the load torque which is generated from the motor transitionally fluctuates and therefore the load current value or load torque value measured during the period of transitional fluctuation is not a stable, correct value and cannot be used to detect a foreign object caught in the window correctly. Therefore, in the load current based type of power window apparatus or the load torque based type of power window apparatus, an operation to detect a foreign object caught in the window is not performed during the period of instability (motor startup period) from the start of the motor until the motor load current value or motor load torque value is stabilized or becomes almost constant, but such an operation is performed just after completion of this period of instability.
In the load torque based type power window apparatus in particular, the motor load torque may fluctuate to a relatively large degree during the period of instability, or this period of instability, which lasts until the motor load torque becomes almost constant, may be prolonged.
In other words, for the load torque based type of power window apparatus, the amount of motor load torque variation in the motor startup period varies depending on the following factors: the starting torque characteristic of the motor in use; the structure of the window moving mechanism including the window to be driven by the motor; the type of car; the number of years when the car has been used; the external conditions or environment in which the car is used, and other factors. In addition, the length of the period of instability until the motor load torque becomes almost constant varies as well.
FIG. 4
is a characteristic graph showing an example of the relation between the number of pulses and the motor load torque in the motor startup period in three motors and window moving mechanisms which are arbitrarily chosen; and
FIG. 5
is a characteristic graph showing an example of the relation between the number of pulses and the motor load torque in the motor startup period at different ambient temperatures for a motor and its window moving mechanism.
For three arbitrarily chosen motors A, B and C, the characteristic curves of motors A, B and C are represented by a, b and c, respectively, as shown in FIG.
4
. From this figure, the characteristics of motors A, B and C in the startup period may be compared and described as follows. The characteristic curve a for the motor A shows that the variation in motor load torque is the largest and the period of instability (a period required until the motor load torque becomes almost constant) is the longest, and the end of the period of instability is just before pulse number
200
; the characteristic curve b for the motor B shows that the variation in motor load torque is smaller than in the characteristic curve a and the period of instability is shorter than in the characteristic curve a, and the end of the period of instability is slightly beyond pulse number
150
; and the characteristic curve c for the motor C shows that the variation in motor load torque is the smallest and the period of instability is the shortest, and the end of the period of instability is before pulse number
150
.
Namely, the motor load torque variation in the motor startup period and the length of the period of instability (a period which lasts until the motor load torque becomes almost constant) differ among these motors and window moving mechanisms for opening/closing the windows. It may also be said that the motor load torque variation and the period of instability differ among any other chosen motors and window moving mechanisms.
The characteristic curve of a chosen motor D at an ambient temperature of 100° C. and that at an ambient temperature of −40° C. are represented by d
1
and d
2
, respectively, as shown in FIG.
5
. The characteristic curve d
1
concerning the startup period for motor D shows that the variation in motor load torque is larger and the period of instability (a period required until the motor load torque becomes almost constant) is longer, and the end of the period of instability is slightly beyond pulse number
150
; on the other hand, the characteristic curve d
2
shows that the variation in motor load torque is smaller than in the characteristic curve d
1
and the period of instability is slightly shorter than in the characteristic curve d
1
, and the end of the period of instability is before pulse number
150
.
This means that even in the same motor and window moving mechanism used for opening/closing the window, the motor load torque variation in the motor startup period and the length of the period of instability (a period which lasts until the motor load torque becomes almost constant) differ depending on the external conditions or environment in which they are used.
For the above reason, in the load torque based type of power window apparatus, the time to start detection for a foreign object caught in the window is preset to a time when most motors have ended their period of instability and have entered the period of stability (for example, a time when pulse number
200
is reached as shown in FIG.
4
), because the load torque characteristic in the motor startup period differs among motors and window moving mechanisms for opening/closing the window, as discussed above.
For the abovementioned load torque based type of power window apparatus, in which the time to start detection for a foreign object in the window is preset to
Alps Electric Co. ,Ltd.
Brinks Hofer Gilson & Lione
Ro Bentsu
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