Patent Application
20100269857
This application claims the benefit of German Patent Application No. 10 2009 018 338.8 filed on Apr. 23, 2009.
The disclosure relates to a method for operating an attachment device for a vacuum cleaner. The disclosure also relates to an attachment device that is particularly suitable for carrying out the method.
Methods for operating attachment devices for vacuum cleaners are generally known. The attachment devices concerned have an electrically rotatable brush roller and a motor for driving the same, and are used, for example, to clean carpeted floors. During operation, the brush roller usually rotates in one direction, but there are known methods where a direction of rotation of this brush roller is reversed during operation, and generally in such a way that the brush roller always rotates in a direction of movement of the attachment device, thus facilitating movement of the attachment device. A method of this kind is described, for example, in DE 689 05 252 T2 and EP 1 352 603 A1.
However, when vacuuming with attachment devices that include a rotatable brush roller, such brush roller may happen to get jammed, for example, in response to garments, rugs, or rug fringes accidentally getting caught and wound up by the brush roller. In such a case, usually, the motor of the brush roller turns off, and the object that was caught must be removed manually, for example, by pulling on it. To do this, it is necessary to overcome the resistance of the brush roller motor while the motor is off.
In an embodiment, the present disclosure provides a method for operating an attachment device for a vacuum cleaner in which the attachment device includes an electrically rotatable brush roller and a motor for driving the same. The method includes rotating the brush roller in a normal operational direction of rotation during operation and rotating the brush roller in a reverse direction of rotation opposite to the normal operational direction when the brush roller is detected to be jammed.
The disclosure provides a method which allows objects that are wound up on the brush roller to be removed more easily, and to provide an attachment device for carrying out this method.
To this end, in a method for operating an attachment device for a vacuum cleaner, the attachment device including an electrically rotatable brush roller and a motor for driving the same, and the brush roller being rotated in a normal operational direction of rotation during operation, provision is made for the brush roller to be rotated in a direction opposite to the normal operational direction of rotation—reverse direction of rotation—when the brush roller is detected to be jammed.
The advantage of the disclosure is that it allows objects wound up on the brush roller to be wound off automatically in the manner described herein. Thus, a user does not need to pull on the object, so that the object does not get damaged, for example, by the pulling force that must be exerted to overcome the resistance of the motor. When, for example, rug fringes are caught in the brush roller, the attachment device is generally very close to the surface of the rug, so that there is little space to free the fringes by hand. In this case, too, rotating the brush roller in a reverse direction allows the rug fringes to be released in a simple and rapid manner.
The motor is preferably a brushless permanent magnet motor. This is an advantage, because the commutators required in commutator motors are subject to substantial wear, which may lead to malfunctions. In addition, this allows for sensorless monitoring of the motor, for example, by monitoring the current consumption, which eliminates the need for failure-prone sensors, such as, for example, Hall sensors. When using a brush roller motor which is controlled via three phases, the direction of rotation can be reversed in a simple and generally known manner by interchanging two phases.
Advantageous embodiments are the subject matter of the dependent claims. The antecedents used therein refer, by the features of the respective dependent claim, to a further embodiment of the subject matter of the main claim; they are not to be understood as renouncing attainment of an independent protection of subject matter for the combinations of features of the dependent claims having the main claim as antecedent reference. Furthermore, with regard to an interpretation of the claims in the case of a more detailed concretization of a feature in a subordinate claim it is to be assumed that a restriction of said kind is not present in the respective preceding claims.
Preferably, jamming is detected when the current consumption of the motor exceeds a predetermined or predeterminable threshold value. This takes into account that not all surfaces present identical vacuuming conditions. In particular, depending on the surface to be vacuumed, the current consumption may slightly increase already when vacuuming a carpeted floor having a pile of varying length or thickness. In such a situation, no jamming will be detected when the threshold is set to a higher value in which such surfaces are suitably taken into account. Thus, in the case of surfaces that offer somewhat greater resistance to movement, the use of the attachment device is not impaired by reverse rotation, which is usually unwanted in such circumstances.
Particularly preferably, jamming is detected when the current consumption exceeds the threshold value for a predetermined or predeterminable period of time. In this manner, brief, sharp increases in current consumption, which may be caused by the attachment device “getting stuck” on the surface to be vacuumed, are prevented from being interpreted as jamming and causing the brush roller to be rotated in a reverse direction. This avoids unwanted rotation in reverse, thus preventing the movement of the attachment device from being additionally hindered.
Preferably, the brush roller is rotated in a reverse direction by a predetermined or predeterminable angle—angle of reverse rotation—upon occurrence of jamming. Suitable values for the angle of rotation were found to be in the range from 15 to 360 degrees. Reverse rotation through such an angle may prevent wound-up objects from being wound up again when brush roller is rotated too far in the opposite direction. In the case of a small angle of reverse rotation, such as 15 degrees, the object may possibly not be completely released, but at least be loosened, so that it can then be easily removed by slightly pulling on it. Moreover, it is possible to return to the normal operational direction of rotation more rapidly and resume the cleaning operation.
In an alternative embodiment, the motor of the brush roller is stopped upon occurrence of jamming, and the brush roller is rotated stepwise in the reverse direction by a predetermined or predeterminable angle each time a switch element is actuated. Thus, reverse rotation of the brush roller does not occur automatically, but can be adjusted to the type of object wound up. For example, the switch element may be actuated by a user who decides on how far to reverse the brush roller by actuating the switch element a corresponding number of times. This facilitates removal of longer and/or thinner objects, which may sometimes wind up around the brush roller several times.
Preferably, a rotational speed at which the brush roller is rotated in the reverse direction in the event of jamming is lower than a rotational speed in the normal operational direction of rotation. In this manner, objects being wound off are prevented from being wound up in the opposite direction of rotation.
When the brush roller is returned to operation in the normal operational direction of rotation, for example, by pressing a start button, after jamming has been detected and, as the case may be, after the brush roller has been rotated back, the point in time at which normal operation is resumed can be chosen by the user. This allows the user to first remove the loosened objects, if necessary, or to place the attachment device on a different spot, thereby preventing objects from being immediately wound up again when the brush roller is reactivated. The start button may be disposed, for example, directly on the attachment device. A simpler alternative is to reactivate the brush roller of the attachment device by turning the vacuum cleaner first off and then on again by a main switch instead of using the start button. In this case, the attachment device does not need an additional switch.
Preferably, provision is made for a generator mode of operation to generate a signal to resume operation in the normal operational direction of rotation. Operation of the brush roller motor in generator mode is achieved by pushing the attachment device in a particular direction. In the process, the friction created by the contact of the brush roller with the floor causes the brush roller to rotate. This rotation results in the motor generating a voltage that can be used as a signal to return the brush roller to operation in the normal operational direction of rotation. In this manner, the cleaning operation can be rapidly resumed without further manipulation by the user.
Preferably, during operation, the normal operational direction of rotation of the brush roller is adjusted to match a forward or backward movement of the attachment device, and the reverse direction of rotation is determined according to the particular normal operational direction of rotation. To this end, the respective normal operational direction of rotation may be stored in a control unit of the brush roller motor in order for the brush roller to rotate in the respective opposite direction in the event of jamming.
In an attachment device for a vacuum cleaner, the attachment device having an electrically rotatable brush roller and a motor for driving the same, provision is made for means for detecting jamming of the brush roller and for emitting a jamming signal to reverse the direction of rotation of the motor, said means, as a whole, being referable to as “jamming detection means”.
Furthermore, advantageous embodiments of the attachment device mentioned above and used to achieve the object mentioned earlier using the above-described method and embodiments thereof has, as essential features, means for carrying out individual steps encompassed by the method and embodiments thereof. It this respect, reference is essentially made to the preceding description of the method and embodiments thereof
Preferably, a current sensor for measuring the current consumption of the brush roller motor, and a monitoring device for emitting a jamming signal when the current exceeds a predetermined or predeterminable threshold value, are disposed in the attachment device. This keeps signal paths short during current consumption monitoring and transmission to the monitoring device, which in turn is beneficial for EMC and reduces the cost of wiring, etc.
Particularly preferably, the attachment device has provided therein means for monitoring the presence of the jamming signal for a period of time exceeding a predetermined or predeterminable period of time. These means may be included, for example, in a control unit for controlling the motor. A simple example is a counter which is started by the jamming signal and which indicates the elapse of a period of time when this period of time has expired.
Also preferably, a push button is provided, for example, on the top of the attachment device, as the switch element for rotating the brush roller, in particular stepwise, in the reverse direction by a predetermined or predeterminable angle. Each time a user actuates the push button, the brush roller is rotated back by this angle. The button may be actuated as many times as desired or necessary to loosen wound-up objects.
Preferably, the attachment device is provided with a start button, for example, on a top thereof, allowing the brush roller to be rapidly returned to operation in the normal operational direction of rotation after a jamming event has occurred and, as the case may be, after the brush roller has been rotated back. Alternatively, starting may be accomplished through generator action.
In a preferred embodiment, the attachment device includes means enabling the direction of operation of the brush roller to be reversed during operation, particularly according to a forward or backward movement of the attachment device. In this manner, the movement of such an attachment device over a surface may be facilitated, because the friction with the surface caused during the rotation of the brush roller produces a force that promotes said movement when the brush roller rotates in the corresponding direction of movement. Otherwise, the movement of the attachment device may be hindered in one direction to different degrees, depending on the properties of the surface. An attachment device designed in this manner may further be provided with means for storing a direction in which the brush roller was rotating during normal operation before it jammed, which means may then be used to activate the corresponding reverse direction of rotation that is suitable to release the jam. These means may be disposed, for example, in a control unit of the attachment device.
An exemplary embodiment will be described in more detail below with reference to the drawing. Corresponding objects or elements are identified by the same reference numerals in all figures.
It is understood that neither this or any other exemplary embodiment should be construed as limiting the scope of the claims. Rather, within the framework of the present disclosure, numerous revisions and modifications are possible, in particular such variants and combinations, which, for example, by combining or altering individual features or elements or method steps described in connection with the general or detailed description, as well as the claims, and contained in the drawings, may be inferred by one skilled in the art with regard to achieving the objective, and lead, through combinable features, to a new subject matter or to new method steps or sequences of method steps.
It may be provided for brush roller 16 of attachment device 14 to rotate during normal operation either in one direction only, or to change its direction of rotation during operation according to a forward or backward movement of attachment device 14. In the last-mentioned embodiment, attachment device 14 or control unit 20 includes suitable means capable of determining the direction in which brush roller 16 was last rotating before it jammed, so that brush roller 16 will then rotate back in the respective opposite direction. When returning brush roller 16 to normal cleaning operation, it may rotate, for example, in any direction. However, if the return to normal operation is initiated through generator action, the direction of movement of attachment device 14 is detected by suitable means, and brush roller 16 is then driven in this direction.
Thus, provided are a method for operating an attachment device 14 for a vacuum cleaner 10, and an attachment device 14 operating in accordance with this method, the attachment device having an electrically rotatable brush roller 16 and a motor 18 for driving the same, and brush roller 16 being rotated in a normal operational direction of rotation during operation, provision being made for brush roller 16 to be rotated in a direction opposite to the normal operational direction of rotation—reverse direction of rotation—when brush roller 16 is detected to be jammed. To this end, attachment device 14 is provided with suitable means—jamming detection means 22—for detecting jamming and emitting a jamming signal 24 to reverse the direction of rotation of motor 18.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2009 018 338.8 | Apr 2009 | DE | national |
