Abstract:
The invention relates to a drive system ( 1 ) for driving an automatic cleaning unit, comprising: —a carrier unit ( 7, 10 ); —a drive motor ( 2 ), which is fastened on the carrier unit ( 7, 10 ); —a driveshaft ( 4 ), which is arranged in a rotatable manner on the carrier unit ( 7, 10 ) and can be driven by the drive motor ( 2 ); —an advancement device ( 15 ), which is arranged on the driveshaft ( 4 ) and can be rotated about the driveshaft, wherein the advancement device ( 15 ) is coupled to the driveshaft ( 4 ) in order to generate advancement transversely to the extent of the driveshaft ( 4 ) and in order, when advancement is stopped, to cause the advancement device ( 15 ) to rotate in relation to the carrier unit.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This patent application is the national phase of PCT/EP2011/004222, filed Aug. 23, 2011 which claims the benefit of German Patent Application No. 10 2010 045 096.0, filed Sep. 13, 2010. 
     FIELD OF THE INVENTION 
     The present invention pertains to drive systems for automatic cleaning units and for cleaning units that clean a surface by sweeping the surface over which the cleaning unit passes. 
     BACKGROUND OF THE INVENTION 
     Cleaning units for cleaning floors are generally known. As a rule, these units include a rotating roll, for example, with a brush attachment. The roll, in addition to moving the cleaning unit across a floor surface, also rotates so as to sweep a floor surface with the brush attachment. This type of cleaning unit is frequently operated by hand. Improvements in battery technologies make it increasingly possible to manufacture automatic cleaning units that pass over a floor surface in random movements and thus clean the floor surface. 
     As a rule, automatic cleaning units run in a straight line across an area of the floor surface until they encounter an obstacle. After contact with the obstacle, they change direction, which as a rule is done randomly, and the cleaning unit continues to move in a different direction. 
     For example, U.S. Pat. No. 4,173,809 discloses a battery-operated vacuum cleaner, the drive unit of which includes spherical shells that can rotate in any direction and that can randomly change their movement in any direction. 
     In addition, U.S. Pat. No. 6,571,415 B2 discloses a floor cleaning system having its own drive mechanism, in which the drive unit includes a hollow spherical shell that is attached to the frame so as to rotate freely. Disposed inside the hollow spherical shell is a weighted motor which randomly moves the hollow spherical shell. This causes the cleaning system to move in random movements across the floor, thereby cleaning the floor surface. 
     Because of the spherical drive elements, the drive units for the cleaning systems described above have only one or few points of contact with the floor surface, which limits the transmission of the motive energy required to move the cleaning system forward. This is a disadvantage especially in cases where the cleaning system uses a cleaning cloth or a cleaning brush that is intended to have full-surface contact with the floor surface to be cleaned and therefore requires a high driving power in order to set the cleaning system into motion. 
     Furthermore, in addition to the driving power required to move the cleaning system across the floor surface, it is desirable for a cleaning element that is moved across the floor surface to execute an additional movement, for example, a rotational movement, so as to enhance the cleaning effect. 
     SUMMARY OF THE INVENTION 
     Thus, a general object of the present invention is to provide a drive system for a cleaning unit as well as a cleaning unit that allows sufficiently high driving power to be transmitted to the floor surface so as to move a cleaning element for cleaning dirty floors. An additional object of the present invention is to have the cleaning element execute a movement in addition to the forward propelling movement, so as to enhance the cleaning effect. 
     A first aspect of the invention may pertain to a drive system for driving an automatic cleaning unit. The drive system includes:
         a carrier unit;   a drive motor that is attached to the carrier unit;   a drive shaft that is rotatably disposed on the carrier unit and that is driven by the drive motor; and   a forward propelling unit that is disposed on the drive shaft and that is able to rotate about the drive shaft, with the forward propelling unit being connected to the drive shaft so as to generate a forward propelling movement at right angles relative to the direction of the drive shaft and to cause the forward propelling unit to rotate relative to the carrier unit when the forward propelling movement is obstructed.       

     The idea behind the drive system described above is to provide a drive motor that is disposed on a carrier unit that, relative to a forward propelling unit, is able to rotate about a drive shaft. The drive motor is drivably coupled to the drive shaft. In addition, the drive shaft is connected, e.g., via a gear unit, to one or a plurality of drive rolls. The one or more drive rolls have a driving axle which runs perpendicular to the drive shaft. The one or more drive rolls generate the forward propelling movement, with the driving axle moving in unison with the drive shaft. 
     A forward propelling movement is generated by the drive system whenever the rotational movement of the carrier unit meets resistance, such as is generally the case when the carrier unit supports, e.g., a cleaning element that rests upon the floor surface to be cleaned and thus produces a frictional contact. This causes, e.g., the one or more drive rolls to be driven, thereby moving the cleaning unit in a translational movement across the floor surface. Due to the fact that the cleaning element rests upon the floor surface, the frictional force also acts against the forward propelling unit. As a result, the carrier unit that is coupled to the drive shaft is rotated about the drive shaft, and thus the cleaning element is moved in a rotational movement across the floor surface to be cleaned. 
     When the translational movement across the floor surface is obstructed or blocked, the forward propelling unit is rotated relative to the carrier system, which changes the direction of the subsequently following forward propelling movement, and the cleaning unit that is operated by the drive system continues to move in a different random direction. 
     Because of the fact that the permissible frictional force of the cleaning element acting upon the floor surface is higher than that known from the prior art, the use of such a drive system for cleaning units leads to a markedly higher cleaning effect. In addition, the navigation around obstacles is considerably smoother, which overall increases the cleaning surface swept within a specific period of time. The coupled drive system in which the rotational movement and the forward propelling movement are coupled to each other via the drive system makes it possible for the cleaning unit to make closer contact with, and move for a longer period of time along, obstacles and edges. Thus, cleaning of these critical areas of a floor surface is improved. 
     The carrier unit can also support a mounting element that encloses the forward propelling unit and to which a cleaning element, in particular a cleaning cloth and/or a cleaning brush, can be attached. 
     The carrier unit can be constructed so as to be able to rotate the cleaning element about the forward propelling unit whenever the forward propelling unit generates a forward propelling movement. 
     In particular, the forward propelling unit can be coupled to the drive shaft in such a manner that the forward propelling unit begins to rotate as soon as the forward propelling movement is obstructed beyond a certain threshold value. 
     The drive shaft can be coupled to a damper element, with the damper element having a damping capacity that makes it possible to set a predetermined distribution of the motive energy provided by the drive motor between a rotational movement of the carrier unit and the forward propelling movement. 
     The forward propelling unit can have a minimum of one drive roll that is disposed on a driving axle that is coupled to the drive shaft, with the driving axle running at right angles relative to the drive shaft and being coupled to said drive shaft via a gear unit. 
     In addition, the forward propelling unit can comprise a minimum of one auxiliary roll that is disposed on the base unit so as to be laterally offset relative to the driving axle, with the axis of rotation of the auxiliary roll running substantially parallel to the driving axle. This ensures more stable straight line travel and an increase in the friction of the forward propelling unit so as to prevent rotation; in this manner, the auxiliary roll makes it possible to adjust the distribution of the motive energy of the drive system between the forward propelling movement and the rotational movement of the carrier unit. 
     A second aspect of the present invention pertains to a cleaning unit with the drive system described above. The drive system can be enclosed in a housing that, in the direction of the drive shaft, is preferably connected in a spring-loaded manner to the drive system. The spring-loaded connection ensures that whenever pressure is exerted on the housing from above, the pressure does not act directly on the forward propelling unit. Instead, the force is absorbed by the housing, especially when the housing makes contact with the floor surface before the spring has reached the end of its travel path. 
     In addition, the shape of the housing can be noncircular relative to a plane parallel to the plane of the forward propelling movement of the forward propelling unit. This reliably ensures that a rotation of the housing is blocked when the cleaning unit encounters an obstacle so that the rotation of the forward propelling unit starts immediately. 
     The carrier unit can be in the form of a mounting element, in particular a mounting ring, that is disposed parallel to the plane of the forward propelling movement of the forward propelling unit. 
     The mounting element can have a mechanism for attaching a cleaning element, in particular for creating a hook and loop fastener for connection to the cleaning element. 
     In addition, the mounting element can be surrounded by a weighting element so as to push an attached cleaning element against a floor surface. 
     According to one embodiment of the invention, the mounting element can be constructed so as to be able to rotate about the housing. 
     In addition, the cleaning unit can include a control unit for controlling the direction of rotation of the drive motor. The control unit can be constructed so as to reverse the drive motor at specific time intervals or via manual operation. This improves the cleaning coverage of complex rooms and makes it easier to maneuver out of narrow spaces and to remove obstacles. 
     According to one embodiment of the invention, the control unit can be constructed so as to reverse the direction of rotation of the drive motor as soon as it is determined that the translational and rotational movement of the forward propelling unit is completely blocked. In this manner, it is possible to more readily resolve situations in which the movement is blocked. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       Preferred embodiments of the invention will be described in greater detail below with reference to the attached drawings. As can be seen: 
         FIG. 1  is a schematic side view of an exemplary drive system for a cleaning unit. 
         FIG. 2  is a side sectional view of an embodiment of a cleaning unit for sweeping a floor surface. 
         FIG. 3  is a perspective view showing the bottom of the cleaning unit of  FIG. 2 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  provides a schematic view of a drive system  1  for operating a cleaning unit. The drive system  1  includes a drive unit  2 , for example, in the form of an electric motor. To power the electric motor  2 , it is supplied with electric power by a power storage unit  6 . 
     The electric motor  2  is coupled to a drive shaft  4  via a gear unit such that the electric motor  2  drives the drive shaft. For use in a cleaning unit, the drive shaft  4  is disposed substantially perpendicular relative to the floor surface to be cleaned by the cleaning unit. To this end, the electric motor  2  can include, in particular, a drive shaft with a pinion  3 , by means of which the drive shaft  4  is driven. To transmit the input torque to the drive shaft  4 , the drive shaft  4  can have a gear wheel  5  that engages the pinion  3 . 
     In addition, the drive system can include a base unit  7  to which the electric motor  2  and the power storage unit  6  are connected, for example, via a mount  8 . In addition, the base unit  7  serves to hold the drive shaft  4  substantially in a vertical position with the drive shaft  4  mounted so as to be torsionally movable relative to the base unit  7 . The drive shaft  4  is preferably mounted on two points of support arranged at a distance from each other. 
     The base unit  7  is rigidly connected to a mounting ring  10  that constitutes the carrier unit and that, when used in the cleaning unit, rests close upon the floor and is disposed substantially parallel to the floor surface. The mounting ring  10  serves to hold a cleaning element in the form of a cleaning cloth, a cleaning brush or the like. The cleaning element can preferably be detachably connected to the mounting ring  10 , for example, by means of a hook and loop fastener, and is thus replaceable. To ensure that, if a cleaning cloth is used, the cleaning cloth is in contact with the largest possible surface of the floor surface, a flexible weighting element  11  can be disposed along the outside circumference of the mounting ring  10 , with the weighting element  11  substantially surrounding the mounting ring  10  in the form of a ring. 
     The cleaning cloth that can be attached to the mounting ring  10  preferably has the shape of a ring as well. The cleaning cloth can have an outside diameter equal to or larger than the outside diameter of the weighting element and an inside diameter that is substantially identical to the inside diameter of the mounting ring  10 . When placed onto the floor surface, the cleaning cloth is in full-surface contact with the floor surface. The inside edge of the cloth is pushed by the mounting ring  10 , and the outside edge by the weighting element  11 , against the floor surface. 
     Disposed in the inside area that is surrounded by the mounting ring  10  is a forward propelling unit  15  with two drive rolls  16  that are rigidly connected to each other by a driving axle  17 . The drive rolls  16  preferably have the form of cylinders and are made of a material, e.g., rubber, that has high friction with conventional floor surfaces to be cleaned. In addition, to further increase the friction, the drive rolls can have grooves that run at right angles relative to the circumferential direction. An axle mounting unit  18  holds the driving axle  17  in a horizontal position and substantially perpendicular to the drive shaft  4 . To this end, the axle mounting unit  18  is disposed on the drive shaft  4 , thus ensuring that although the drive shaft is able to rotate independently of the axle mounting unit  18 , the axle mounting unit  18  locks the axle  17  in a position at a right angle relative to the drive shaft  4 . 
     A gear rim  19  is disposed on the end of the drive shaft  4  that faces the forward propelling unit  15 . The gear rim  19  engages a gear wheel  20  that is rigidly disposed on the driving axle  17 . This arrangement enables a rotation of the drive shaft  4  to translate into a rotation of the driving axle  17 . Thus, a rotation of the drive shaft  4  leads to a rotation of the driving axle  17  and, as a result, to a forward propelling movement via the drive rolls  16 . 
     Because of the drive system  1  described above, the motive energy provided by the electric motor  2  and transmitted via the drive shaft  4  is distributed between the forward propelling movement caused by the drive rolls  16  and a rotational movement of the base unit  7  above the floor surface on which the drive system and the drive rolls  16  rest. This enables a cleaning element that is disposed on the mounting ring  10  to rotate about the forward propelling unit  15 . 
     When properly adjusted, if, for example, the cleaning element is a cleaning cloth with which a smooth surface, such as parquet, laminate, tile or stone or the like, is to be cleaned, the use of the drive system above leads to a forward propelling movement caused by the rotation of the drive rolls  16  and, at the same time, to a rotation of the mounting ring  10  about the forward propelling unit  15  so that an attached cleaning cloth is able to rotate about the drive shaft  4 . 
     When a cleaning unit operated by this drive system  1  encounters an obstacle, first the rotation of the base unit  7  with the mounting ring  10  is obstructed or blocked, and the motive energy that had previously been transmitted via the drive shaft  4  to the mounting ring  10  is now completely transmitted to the forward propelling unit  15 . If the obstacle also blocks the rotation of the drive rolls  16 , which preferably have high friction with the floor surface, the motive energy on the drive shaft  4  is translated against the frictional force of the drive rolls  16  on the floor surface into a rotational movement of the forward propelling unit  15  about the drive shaft  4 . The power necessary to cause the forward propelling unit  15  to rotate is high since during the rotational movement, a minimum of one of the drive rolls  16  is moved across the floor surface against the frictional resistance, and thus a rotation of the forward propelling unit  15  preferably takes place only when both the forward propelling movement and the rotational movement of the base unit  7  and its attached mounting ring  10  are blocked. 
     The rotational movement of the forward propelling unit continues as long as the forward propelling movement is obstructed. As soon as the cleaning unit is free to move again because of the changed forward propelling direction and the drive rolls  16  of the forward propelling unit  15  again generate a forward propelling movement of the drive system  1 , the forward propelling unit  15  stops rotating. In other words, the rotation of the forward propelling unit  15  continues until a portion of the motive energy leads either to a rotational movement of the base unit  7  and the cleaning element attached thereto and/or to a forward propelling movement via the drive rolls  16 . As soon as a specific minimum portion of the motive energy is again translated into a forward propelling movement or is used to rotate the cleaning elements, the motive energy is no longer sufficient to cause the forward propelling unit  15  to rotate on the floor surface and the rotation of the forward propelling unit  15  on the floor surface stops as a result of the high frictional force of the drive rolls  16 . Subsequently, the drive system  1  moves the cleaning unit substantially in a straight line in a new direction that is determined by the direction in which the forward propelling unit  15  faces at the time when the forward propelling unit  15  stops rotating. 
       FIG. 2  shows across section through a cleaning unit with the drive system  1  along the perpendicularly disposed drive shaft  4 . As illustrated, the drive unit  1  is disposed in a housing  25  that encloses the drive unit  1 . 
     The housing  25  is connected in a substantially spring-loaded manner to the drive unit  1  so that any pressure on the outside of the housing  25  causes the housing  25  to be lowered to the floor surface, without the pressure being directly exerted on the drive rolls  16  by the drive unit  1 . As a result, the drive unit  1  is protected against any impact on the housing  25 . The housing  25  is connected by a minimum of one spring  26  to the drive unit  1 . 
     In addition, the housing  25  is coupled to the base unit  7  in such a manner that when the base unit  7  rotates on the floor surface, the housing  25  also rotates, i.e., the housing is carried along by the base unit  7  of the drive system  1 . As illustrated in  FIG. 3 , the shape of the housing  25  is noncircular, so that the moment the unit meets an obstacle, the rotational movement of the housing  25 , and thus of the base unit  7  connected thereto, is obstructed, and friction between the outside rim of the housing  25  and the blocking object is avoided as much as possible. The immediate blockage of the rotational movement of the housing  25  subsequently leads to a rotation of the driving axle  17  between the two drive rolls  16 , which causes the cleaning unit  24  to change direction until it encounters another obstacle. 
       FIG. 3  shows the bottom of the cleaning unit  24  and the mounting ring  10  to which the cleaning element, for example, a cleaning cloth or the like, is attached. The cleaning element can be attached, for example, by hook and loop fasteners, with the illustrated embodiment having hoop and loop tapes  27  that are arranged at certain spaced intervals from one another on the mounting ring  10 . 
     In addition, the forward propelling unit  15  of the cleaning unit  24  shown in  FIG. 3  can include one or more auxiliary wheels  28  that are disposed at a distance from the drive rolls  16  in a direction perpendicular to the driving axle  17  and that have an axis of rotation parallel to the drive rolls  16 . The auxiliary wheels  28  are disposed relative to the drive rolls  16  such that the bottom surface of the auxiliary wheels is on approximately the same level as the bottom surface of the drive rolls  16 . 
     The auxiliary wheels  28  serve to improve straight line travel of the forward propelling unit  15  and to increase the resistance of the forward propelling unit  15  to rotation so that a larger portion of the energy of rotation is transmitted to the base unit  7  and to the housing  25 . When the forward propelling unit  15  rotates, the one or more auxiliary wheels  28  are moved across the floor surface at aright angle relative to their direction of travel. However, the auxiliary wheels  28  can also be pushed by spring loading against the floor surface, with the spring force being adjustable so as to regulate the reaction of the cleaning unit  24  when it meets an obstacle. 
     As an alternative or in addition thereto, the rotatability of the forward propelling unit can also be controlled through the selection of the material of the drive rolls  16  and/or through the selection of the size of the bottom surfaces of the drive rolls  16 , which surfaces determine the friction of the drive rolls  16  on the floor surface. In this manner, it is possible to determine the resistance of the forward propelling unit to a rotational movement. 
     According to another embodiment of the invention, a damper element can be disposed between the forward propelling unit  15  and the base unit  7  so as to influence the portion of the motive energy transmitted during a rotation of the base unit  7 . The damper element  29  can be variable with respect to the relative angle between the forward propelling unit  15  and the base unit  7 , thus making it possible to set preferred directions of the forward propelling unit  15  relative to the housing  25  as well as the speed of rotation of the base unit. 
     In an alternative embodiment, the housing  25  is constructed so as to be able to rotate about the base unit of the drive system  1 . In this case, the cleaning element does not rotate when the cleaning unit is in motion. 
     In addition, the cleaning unit  24  can include a control unit for controlling a direction of rotation of the drive motor  2 . The control unit can be constructed so as to reverse the drive motor  2  at specific time intervals or by manual operation. This ensures that the cleaning coverage of complex rooms is improved and that it is easier to maneuver the cleaning unit  24  out of narrow spaces and to remove obstacles. 
     In addition, as soon as it is determined that the translational and rotational movement of the forward propelling unit  15  is completely blocked, the direction of rotation of the drive motor  2  can be reversed, thus allowing situations in which the movement is blocked to be more readily resolved. A complete blockage of the translational and rotational movement can be detected, for example, by monitoring the motor current or by suitable motion sensors. 
     The use of the terms “a” and “an” and “the” and “at least one” and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The use of the term “at least one” followed by a list of one or more items (for example, “at least one of A and B”) is to be construed to mean one item selected from the listed items (A or B) or any combination of two or more of the listed items (A and B), unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention. 
     Preferred embodiments of this invention are described herein. Variations of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to he practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.