This application claims the benefit of priority to Japanese Patent Application No. 2003-068530, herein incorporated by reference.
1. Field of the Invention
The present invention relates to techniques used in a power window apparatus for detecting that an object is caught. In particular, the present invention relates to a technique, in opening/closing a door window of an automobile, for preventing an excessive squeezing force from being applied to a caught object, and for preventing the door window from being erroneously stopped or reversed.
2. Description of the Related Art
In a known technique for detecting an object, a parameter that indicates a motor load imposed on the window glass, when opened/closed by a motor drive, is measured. Then, the measured parameter (motor load torque) is compared with a preset reference median. When the parameter is substantially deviated from the reference median, the motor is stopped or reversed based on the determination that an object is caught (see, for example, Japanese Unexamined Patent Application Publication No. 11-62380 (corresponding to U.S. Pat. No. 6,150,784)). According to this technique, the reference median is set within the entire range where an object can be detected, that is, the range between the fully-closed position and the fully-open position of the window glass, which is included in the entire moving range of the window glass.
In another known technique for detecting that an object is caught in a door window, an external force applied to the window glass is continuously monitored. Then, when a detected external force exceeds a threshold, a driving motor is stopped or reversed based on the determination that an object is caught (see, for example, Japanese Unexamined Patent Application Publication No. 11-131909). A first threshold and a second threshold that is smaller than the first threshold are used to determine whether an object is caught.
In Japanese Unexamined Patent Application Publication No. 11-62380, the reference median is a motor load torque required for a movement of the window glass when no object is caught. Practically, the motor load torque is made up of, for example, the weight of the window glass and the friction between the window glass and a sash, and varies depending on the position in the entire moving range of the window glass. Although the reference medians exist all over the moving range of the window glass, one given position in the moving range is associated with only one reference median.
In Japanese Unexamined Patent Application Publication No. 11-131909, the first threshold and the second threshold are set for detecting that an object is caught when a door of a hardtop vehicle is closed or opened. Therefore, one given position in the moving range of the window glass is associated with two thresholds. In Japanese Unexamined Patent Application Publication No. 11-62380, a value obtained by adding a certain level of an allowable reference value to the reference median is used to determine whether an object is caught. When a motor load imposed on the window glass exceeds this value, it is determined that an object is caught. This value corresponds to the thresholds described in Japanese Unexamined Patent Application Publication No. 11-131909. The allowable reference value is a value determined by converting a maximum allowable force, which can be applied to a caught object, into the motor load torque, or by making some corrections to this value. The maximum allowable force that can be applied is interpreted as an allowable squeezing force that can be applied to a caught object.
In a vehicle, especially an automobile, each window glass, particularly of front seats, normally has an inclined side in front and a horizontal side at the back. An object may be caught either at the inclined side or the horizontal side. When an object is caught at the horizontal side, an external force applied to the object can be detected as a motor load imposed on the window glass. On the other hand, when an object is caught at the inclined side, a less force, compared to the external force applied to the object, is detected as a motor load imposed on the window glass, due to the moment of force (the detail will be described in Description of the Embodiments).
Therefore, in the power window apparatus where only one threshold is provided for one given position in the moving range of the window glass, as disclosed in the above patent documents, even if an appropriate threshold, which is appropriate for detecting an object caught at the horizontal side, is set, an external force exceeding an allowable value may be applied to an object caught at the inclined side of the window. On the other hand, when a lower threshold appropriate for detecting an object caught at the inclined side is set, a minor incident occurring at the horizontal side leads to the determination that an object is caught. As a result, the motor for driving the window glass develops a tendency to malfunction and is, for example, stopped and reversed erroneously.
Accordingly, the present invention aims to provide a power window apparatus that can stop or reverse the motor for driving the window glass, based on a proper determination, when an object is caught either at the inclined side or the horizontal side of the window glass. The present invention also aims to provide a power window apparatus that can prevent the motor from being erroneously stopped or reversed when no object is caught.
To solve the problems described above, a power window apparatus according to the present invention includes a window glass having a horizontal side and an inclined side at the upper end thereof; a window frame for supporting the window glass; a motor for vertically driving the window glass; and a detecting mechanism for determining whether an object caught between the upper end of the window glass and the window frame is located at the horizontal side or the inclined side. In this power window apparatus, two thresholds are set to different values for the horizontal side and the inclined side, the thresholds for determining whether the object is caught or not; a parameter corresponding to a load torque on the motor is measured; and the measured parameter is compared with the corresponding set threshold to stop or reverse the motor when the parameter exceeds the threshold.
In the power window apparatus, moreover, a first threshold of the two thresholds to determine whether the object is caught between the horizontal side and the window frame, and a second threshold to determine whether the object is caught between the inclined side and the window frame are set; and the level of the second threshold is smaller than that of the first threshold.
Further, the detecting mechanism detects that the object is caught between the inclined side and the window frame, and the second threshold is applied for comparison based on a detection output from the detecting mechanism.
Moreover, the second threshold is applied when the detecting mechanism detects that an object is caught between the inclined side and the window frame, and the first threshold is applied when the detecting mechanism detects that no object is caught therebetween.
The present invention achieves the following by applying the above-described mechanisms.
In the power window apparatus according to the present invention, a plurality of thresholds are preset and compared so that the maximum allowable squeezing force is not applied to the object caught, regardless of the position, at the upper end of the window glass vertically moved. Thus, the object can be protected from damage and scratches, and further, the motor can be prevented from erroneously stopped or reversed.
Even if an object is caught at the inclined side of the window glass, the motor can be stopped or reversed, by lowering a threshold, for preventing a force that exceeds the maximum allowable squeezing force from being applied to the object.
Moreover, when no object is caught at the inclined side, the motor can be prevented from being erroneously stopped or reversed by immediately returning the threshold to the previous value.
The power window apparatus having a mechanism for detecting that an object is caught, according to an embodiment of the present invention, will be further described with reference to the drawings.
Referring to
As shown in
When the motor is placed under a load, the motor output (load) torque is determined by detecting varying pulse periods or pulse frequencies from a pulse generator provided to the motor.
Referring back to
In the embodiments of the present invention, therefore, a detecting mechanism is provided for detecting that an object is caught at the inclined side 5 of the window glass 1. The main feature of the present invention is that a threshold for controlling the motor to stop is lowered only when this detecting mechanism detects that contact occurs.
With reference to
When the contact sensor 3 detects the object B, the set value is lowered from the set value A to a set value B. A threshold B is thus determined by adding the reference torque to the set value B. Similarly to the set value A, the set value B is an increase in the motor output torque, as shown in
Although the inclined side 5 described above is linear, the inclined side may be curved. The method used to determine an appropriate set value for the linear inclined side 5 can also be applied to the curved inclined side. That is, in
Number | Date | Country | Kind |
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2003-068530 | Mar 2003 | JP | national |
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4900994 | Mizuta | Feb 1990 | A |
5764008 | Hahn et al. | Jun 1998 | A |
5774046 | Ishihara et al. | Jun 1998 | A |
5932931 | Tanaka et al. | Aug 1999 | A |
6150784 | Nagaoka | Nov 2000 | A |
6704471 | Fowler et al. | Mar 2004 | B1 |
Number | Date | Country |
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11-131909 | May 1999 | JP |
Number | Date | Country | |
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20040178758 A1 | Sep 2004 | US |