Patent Publication Number: US-11638511-B2

Title: Floor cleaning apparatus with offset cleaning unit

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of and priority to U.S. patent application Ser. No. 15/515,855 filed Mar. 30, 2017, issued as U.S. Pat. No. 10,368,709, the entire content of which is hereby incorporated by reference. 
     FIELD OF THE INVENTION 
     This invention relates to a floor cleaning apparatus with a cleaning unit that can be offset, and to a method for cleaning a floor. 
     BACKGROUND OF THE INVENTION 
     Various powered floor cleaning machines are known in the art, including those in which the operator is standing on the floor and walking behind the machine (“walk-behind” machines), those in which the operator is sitting on the machine (“ride-on” machines), and those in which the operator is standing on the machine (“stand-on” machines). 
     Ride-on machines are common in the market for cleaning larger areas. 
     The marketplace desires on the one hand a floor cleaning machine that is capable of cleaning close to a wall, shelf or other boundary area. Fulfilling this need requires that the apparatus have a considerable offset of the cleaning unit, i.e. that the effective cleaning reach of the cleaning assembly of the apparatus extend from the basic footprint of the apparatus itself so that the edges of the floor can be cleaned. 
     Another desire of the marketplace is a floor cleaning machine that is capable of passing through relatively narrow slots or spaces, e.g. the “check-out” area of a store or other industrial or commercial building, or the narrow entrances to service areas of a building. 
     Efforts have been made to address these requirements. 
     One approach is to provide a floor cleaning machine with a cleaning unit with a variable working width. In normal operation, a large working width is employed, but a narrower width can be used that permits the machine to pass through relatively narrow slots or spaces, e.g. check-out areas when needed. Unfortunately, such a system is accompanied by several disadvantages. The mechanical elements of the variable working width cleaning unit are susceptible to exposure to dirt and water; the system is complex; and accessibility for purposes of maintenance is poor. This can lead to a cleaning apparatus with relatively low reliability, and relatively high investment and maintenance costs. 
     Another need in the marketplace is to link the cleaning unit to the steering mechanism of the machine. One commercial approach has been to attach a cleaning unit directly to the steering axle of the steering mechanism so that turning a steering wheel also turns the cleaning unit. One disadvantage of this approach is that it offers no capability to incorporate a transition ratio between the degree of turn of the steering wheel, and the degree of turn of the cleaning unit. 
     It would be desirable to have available a floor cleaning machine that provides an offset cleaning mode that offers the capability of cleaning edge areas close to walls, etc., but also a non-offset cleaning mode that enables the machine to pass through relatively narrow slots or spaces. 
     It would be desirable to have available a floor cleaning machine that provides a mechanism that links the cleaning unit to the steering mechanism of the machine, so that the cleaning unit reorients its position in synchronization with the path of travel of the apparatus, and offers the capability to incorporate a transition ratio between the degree of turn of the steering wheel, and the degree of turn of the cleaning unit. 
     It would be desirable to have available a floor cleaning machine that provides both an offset and non-offset cleaning mode, while at the same time providing a mechanism that links the cleaning unit to the steering mechanism of the machine. 
     It would be also be desirable in some cases to have available a floor cleaning machine that additionally provides a cleaning unit with the capability, whether in the off-set cleaning mode or non-offset cleaning mode, of moving in response to contact with an obstacle. 
     It would be additionally desirable in some cases to have available a floor cleaning machine that does not require a cleaning unit with a variable working width, but instead provides a cleaning unit with a fixed working width. 
     SUMMARY OF THE INVENTION 
     In a first aspect, a floor cleaning apparatus for cleaning a floor, the apparatus adapted to traverse a path of travel, comprises a housing, a plurality of wheels by which the floor cleaning apparatus is adapted to move across the floor in a direction of travel, the direction of travel at least partially defining a front end, a back end, and first and second lateral sides of the floor cleaning apparatus, a motive device for moving the apparatus across the floor, a steering mechanism, and a cleaning assembly for cleaning the floor. The cleaning assembly comprises a cleaning unit and an offset mechanism adapted to move the cleaning unit to or from an offset position. 
     In a second aspect, a method for cleaning a floor comprises providing a floor cleaning apparatus for cleaning a floor, the apparatus adapted to traverse a path of travel, comprising a housing, a plurality of wheels by which the floor cleaning apparatus is adapted to move across the floor in a direction of travel, the direction of travel at least partially defining a front end, a back end, and first and second lateral sides of the floor cleaning apparatus, a motive device for moving the apparatus across the floor, a steering mechanism, and a cleaning assembly for cleaning the floor. The cleaning assembly comprises a cleaning unit, and an offset mechanism adapted to move the cleaning unit to or from an offset position. The method for cleaning the floor further comprises navigating the apparatus across the floor while cleaning the floor. 
     In a third aspect, a floor cleaning apparatus for cleaning a floor, the apparatus adapted to traverse a path of travel, comprises a housing, a plurality of wheels by which the floor cleaning apparatus is adapted to move across the floor in a direction of travel, the direction of travel at least partially defining a front end, a back end, and first and second lateral sides of the floor cleaning apparatus, a motive device for moving the apparatus across the floor, a steering mechanism, and a cleaning assembly for cleaning the floor. The cleaning assembly comprises a cleaning unit and a swing mechanism linking the cleaning unit to the steering mechanism, at a pivot wheel spaced from the steering mechanism, such that when the floor cleaning apparatus is in an operative mode, the cleaning unit reorients its position in synchronization with the path of travel of the floor cleaning apparatus. 
     In a fourth aspect, a method for cleaning a floor comprises providing a floor cleaning apparatus for cleaning a floor, the apparatus adapted to traverse a path of travel, comprising a housing, a plurality of wheels by which the floor cleaning apparatus is adapted to move across the floor in a direction of travel, the direction of travel at least partially defining a front end, a back end, and first and second lateral sides of the floor cleaning apparatus, a motive device for moving the apparatus across the floor, a steering mechanism, and a cleaning assembly for cleaning the floor. The cleaning assembly comprises a cleaning unit and a swing mechanism linking the cleaning unit to the steering mechanism, at a pivot wheel spaced from the steering mechanism, such that when the floor cleaning apparatus is in an operative mode, the cleaning unit reorients its position in synchronization with the path of travel of the floor cleaning apparatus. The method for cleaning the floor further comprises navigating the apparatus across the floor while cleaning the floor. 
     In a fifth aspect, a floor cleaning apparatus for cleaning a floor, the apparatus adapted to traverse a path of travel, comprises a housing, a plurality of wheels by which the floor cleaning apparatus is adapted to move across the floor in a direction of travel, the direction of travel at least partially defining a front end, a back end, and first and second lateral sides of the floor cleaning apparatus, a motive device for moving the apparatus across the floor, a steering mechanism, and a cleaning assembly for cleaning the floor, and a lifting device adapted to selectively raise and lower the cleaning assembly. The cleaning assembly comprises a cleaning unit, an offset mechanism adapted to move the cleaning unit to or from an offset position, and a swing mechanism linking the cleaning unit to the steering mechanism, such that when the floor cleaning apparatus is in an operative mode, the cleaning unit reorients its position in synchronization with the path of travel of the floor cleaning apparatus. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention is illustrated by reference to the following drawing figures wherein: 
         FIG.  1    is a perspective view of a floor cleaning apparatus; 
         FIG.  2    is a perspective view of a portion of a floor cleaning apparatus; 
         FIG.  3    is a side elevational view of a portion of a floor cleaning apparatus; 
         FIG.  4    is a perspective view of a portion of a cleaning assembly; 
         FIG.  5    is a perspective view of a lifting device and offset mechanism; 
         FIG.  6    is a perspective exploded view of a lifting device and cleaning assembly; 
         FIG.  7    is a top plan view of a relevant portion of a floor cleaning apparatus, with the cleaning unit in an offset cleaning mode, and the apparatus moving in a forward direction; 
         FIG.  8    is a bottom plan view of the floor cleaning apparatus of  FIG.  7   ; 
         FIG.  9    is a top plan view of a relevant portion of a floor cleaning apparatus, with the cleaning unit in an offset cleaning mode, and the apparatus turning to the left; 
         FIG.  10    is a bottom plan view of the floor cleaning apparatus of  FIG.  9   ; 
         FIG.  11    is a top plan view of a relevant portion of a floor cleaning apparatus, with the cleaning unit in an offset cleaning mode, and the apparatus turning to the right; 
         FIG.  12    is a bottom plan view of the floor cleaning apparatus of  FIG.  11   ; 
         FIG.  13    is a top plan view of a relevant portion of a floor cleaning apparatus, with the cleaning unit in a non-offset cleaning mode, and the apparatus moving in a forward direction; 
         FIG.  14    is a bottom plan view of the floor cleaning apparatus of  FIG.  13   ; 
         FIG.  15    is a top plan view of a relevant portion of a floor cleaning apparatus, with the cleaning unit in a non-offset cleaning mode, and the apparatus turning to the left; 
         FIG.  16    is a bottom plan view of the floor cleaning apparatus of  FIG.  15   ; 
         FIG.  17    is a top plan view of a relevant portion of a floor cleaning apparatus, with the cleaning unit in a non-offset cleaning mode, and the apparatus turning to the right; and 
         FIG.  18    is a bottom plan view of the floor cleaning apparatus of  FIG.  17   . 
     
    
    
     DEFINITIONS 
     “Cleaning” and the like herein refers to treating a floor; in one embodiment, this involves the use of a cleaning fluid and at least one brush, but alternatively or additionally refers to any of burnishing, polishing, vacuuming, sweeping, or brushing, with or without a cleaning fluid, or otherwise affecting the condition of, a floor. 
     “Offset” and “offset mode” and the like herein refer to a position of the cleaning unit, and to a cleaning mode, in which the cleaning unit is configured to project sufficiently beyond one lateral side of the floor cleaning apparatus to effect cleaning of areas of the floor, e.g. edge areas, beyond a lateral side of the floor cleaning apparatus per se, i.e. beyond the footprint of the apparatus per se. “Non-offset” and “non-offset mode” and the like herein refers to a position of the cleaning unit, and a cleaning mode in which the cleaning unit is configured not to project significantly beyond either lateral side of the floor cleaning apparatus per se, i.e. not significantly beyond the footprint of the apparatus per se. The floor cleaning apparatus disclosed herein is configured to operate selectively in either an offset or non-offset cleaning mode. 
     “Fixed working width” with respect to the cleaning unit herein means that the working width of the cleaning unit itself, i.e. the width of the portion of the unit that effects cleaning, remains constant whether the apparatus is in an offset mode or non-offset mode. 
     “Operative mode” and the like herein refers to a mode in which the cleaning unit is activated. 
     “Navigational mode” and the like herein refers to a mode in which the floor cleaning apparatus is traversing a floor surface, with the cleaning unit either activated or deactivated. 
     DETAILED DESCRIPTION OF THE INVENTION 
     The drawings illustrate the configuration and operation of a floor cleaning apparatus  10  in accordance with the invention. Apparatus  10  includes a housing  12 . In one embodiment, housing  12  includes a forward component  14 , an intermediate component  16 , and a rearward component  18 . 
     Apparatus  10  is adapted to move across the floor in a direction of travel, the direction of travel at least partially defining, in one embodiment, a front end  15 , a back end  19 , and first, left  17  and second, right  21  lateral sides of the apparatus. 
     Apparatus  10  traverses the floor by means of a plurality of wheels. In one embodiment, the apparatus can include two front wheels, i.e. left front wheel  20  and right front wheel  22  connected by a front axle  42 , and two rear wheels, i.e. left rear wheel  24  and right rear wheel  26  connected by a rear axle  44 . The two front wheels  20 ,  22  can be spaced apart a distance equal to the distance between the two rear wheels  24 ,  26 . Alternatively, the front wheels  20 ,  22  can be spaced apart a distance greater than, or less than, the distance between the two rear wheels  24 ,  26 . Alternatively, the apparatus can have a single front wheel and a pair of rear wheels; or a pair of front wheels and a single rear wheel. The apparatus includes at least one drive wheel. Any or all of the wheels can be drive wheels, and the apparatus can include one or more caster or free wheels. The plurality of wheels by which the floor cleaning apparatus is adapted to move across the floor in a direction of travel, can include one or more drive wheels, such as a pair of driving wheels for moving the body, a motor, such as an electric motor, for directly or indirectly driving the wheel or wheels, and steering and speed control members for operating the driving motor. Steering may either be manual or by way of differentiated control of individual wheel speeds. 
     Apparatus  10  includes a motive device  27  (such as at least one motor, not explicitly shown) for moving the apparatus  10  across the floor. Drive wheels can be connected to and powered by electric motors indirectly by e.g. a belt or a chain, but other connections can also be used, e.g., the wheels can be individually powered by hub motors. 
     Apparatus  10  includes a steering mechanism  29 , which can include a conventional steering wheel  30 . Instead of a steering wheel, mechanism  29  can have other configurations; for example, the apparatus  10  can comprise two hand gears or levers, one for each front wheel, which are pulled forward or backward, etc. Steering mechanism  29  also includes the appropriate steering linkage  34  (see  FIGS.  2  &amp;  3   ) to operationally couple e.g. the steering wheel  30  to the wheels  20 ,  22  used to guide the path of the floor cleaning apparatus  10 ; as well as a steering housing  32  to accommodate the steering linkage  34 . Steering mechanism  29  can also include a user interface or dashboard. Steering can be controlled by the front wheel or wheels  20 ,  22 , or by the back wheel or wheels  24 ,  26 . 
     Apparatus  10  includes a cleaning assembly  50  for cleaning the floor. Cleaning assembly  50  includes a cleaning unit  60 . In one embodiment, cleaning unit  60  comprises a brush assembly. Cleaning unit  60  can include one or more brushes, such as a circular brush or brushes, suitably powered by an electric motor or other motive device to turn the brushes when the apparatus is in cleaning mode. In one embodiment, cleaning unit  60  includes a left brush  62  and a right brush  64 . In one embodiment, these brushes operate to rotate in opposite directions so as to maximize the scrubbing function while moving soil and spent liquid toward a region under the machine where an optional squeegee/vacuum  85  can pick up the spent liquid from the floor. The brushes can be of any suitable material, size, shape, and bristle density and pattern. In one embodiment, brushes  62  and  64  are offset from each other with respect to the longitudinal centerline of the floor cleaning apparatus; i.e. a brush centerline running through the center of the two brushes is in one embodiment not perpendicular to the longitudinal center line of the apparatus, or is not transverse to the direction of travel of the apparatus during operation. Such an arrangement minimizes the lateral extent of the cleaning unit, when operating in non-offset mode, to control the lateral extent of the apparatus, and so that the apparatus  10  can pass through relatively narrow slots, spaces or passageways. 
     Alternatively or additionally, the cleaning unit  50  can comprise a brush assembly in combination with a dispenser for dispensing a cleaning solution onto the floor; a burnishing device; a polishing device; a sweeping device; a vacuum device; or any suitable combination of the above. 
     Cleaning assembly  50  also includes in one embodiment an offset mechanism  70  adapted to move the cleaning unit to or from an offset position. As shown in  FIG.  5   , offset mechanism  70  enables the cleaning unit to move from a non-offset position and cleaning mode to an offset position and cleaning mode, or from an offset position and cleaning mode to a non-offset position and cleaning mode. The floor cleaning apparatus disclosed in this embodiment is configured to operate selectively in either an offset or non-offset cleaning mode. The horizontal arrows of  FIG.  5    represent the field of motion of offset mechanism  70 . Offset mechanism  70  is supported within the framework of lifting device  90 . The shifting or moving action of offset mechanism  70  can be accomplished mechanically or electrically. For instance, mechanical actuation might occur via a suitable manual shifting device, (e.g. by suitable linkage to a food pedal such a pedal  92 , see  FIG.  3   , or to a hand-operated lever). In an embodiment illustrated in  FIG.  3   , pushing down on and then releasing the foot pedal  92  activates the offset mechanism  70  to move the mechanism, and thus the cleaning unit  60 , from a non-offset position and mode to an offset position and mode. Repeating this action moves mechanism  70 , and thus the cleaning unit  60 , from the offset position and mode back to the non-offset position and mode. Similarly, in embodiments not explicitly shown, the offset mechanism  70  might be actuated electronically by the operator activating a button, switch, touch panel or other input device to actuate a DC or AC motor such as a servomotor or a linear motor. A motor (not shown) can move the cleaning unit  60  to and from the offset position with less physical input from an operator. This offset movement can be accomplished when the cleaning unit  60  is in a lower or operative position (e.g. when a brush assembly is in contact with the floor) or when the cleaning unit  60  is in a raised or non-operative position (e.g. when a brush assembly is not in contact with the floor). This latter configuration of the apparatus may occur e.g. when the apparatus is being navigated from one location to another. 
     The cleaning unit  60  in one embodiment includes a biasing member  51 , such as one or more springs (see  FIGS.  5  and  6   ) that facilitates movement of the offset mechanism  70  and thus cleaning unit  60  to and from an offset position. When the apparatus is operating in an offset position and mode, and the cleaning unit bumps into an obstacle (wall, etc.), the mechanism  70  and cleaning unit  60  will move toward a non-offset position, effectively moving toward the underside of the apparatus; after engagement with the obstacle has discontinued, mechanism  70  and cleaning unit  60  return to their offset position with the assistance of the one or more biasing members  51 . One or more edge wheels  52  are situated along the peripheral edges of the cleaning unit  60 . The edge wheels  52 , in combination with the biasing member(s)  51 , serve to minimize damage to the cleaning unit  60  and/or any obstacles since the wheels  52  will roll along the surface of an obstacle while the cleaning unit  60  moves towards the underside of the apparatus  10  under the force of any impact. 
     Cleaning assembly  50  includes in one embodiment a swing mechanism  80  (see  FIGS.  4 ,  5 , and  6   ) linking the cleaning unit  60  to the steering mechanism  29  such that when the floor cleaning apparatus  10  is in an operative mode, the cleaning unit  60  reorients its position in synchronization with the path of travel of the floor cleaning apparatus  10 . This component and functionality of the floor cleaning apparatus  10  is available both when the apparatus operates in an offset cleaning mode, and when the apparatus operates in a non-offset cleaning mode. 
     In another embodiment, when the floor cleaning apparatus  10  is in a navigational mode, the cleaning unit  60  reorients its position in synchronization with the path of travel of the floor cleaning apparatus  10 . 
     Swing mechanism  80  can include e.g. a pivot wheel  81 , and is connected, in the illustrated embodiment, to support plate  73  of the cleaning assembly  50 , and by means of endless belt or cable  82  (e.g., a Bowden cable) is also connected to steering mechanism  29 . In operation, as an operator of the floor cleaning apparatus  10  turns to the left or the right using the steering mechanism  29 , the cleaning unit  60  swings and reorients in synchronization with the steering mechanism  29 . As illustrated, the cleaning unit  60  pivots about the axis of the pivot wheel  81 . In other embodiments, the cleaning unit  60  may be configured to pivot about multiple pivot points, such as about multiple pivot wheels  81  that are rotatably driven by multiple endless cables  82 . This swing functionality provides operational efficiency compared with a system in which the cleaning unit does not respond to and synchronize a change in its orientation with a change in the path of travel of the floor cleaning apparatus. In embodiments that include the deposition of a cleaning fluid onto the floor, and a squeegee/vacuum system  85  for picking up spent cleaning fluid, the wetted cleaning path on the floor should be completely or nearly covered by the cleaning unit, i.e. the spent cleaning fluid should be captured by the squeegee/vacuum system  85  and sucked up from the floor, even when the floor cleaning apparatus is making a sharp turn. Conventionally, this function requires a long squeegee/vacuum system  85  (suction foot) to be sure to pick up all the spent cleaning fluid, but such an arrangement is at odds with the need to drive through narrow floor areas. The swing mechanism of the invention enables the use of a relatively short squeegee/vacuum system  85  while still providing effective suction of spent cleaning fluid even during sharp turns of the apparatus. 
     In one embodiment, swing mechanism  80  includes the capability of incorporating a transition ratio between the degree of turn of the steering wheel, and the degree of turn of the cleaning unit. 
     In one embodiment, swing mechanism  80  is not linked directly to the steering axle of the steering mechanism. 
     In one embodiment, the swing mechanism  80  includes a pivot wheel  81  positioned above the cleaning unit  60 , as shown in  FIG.  6   . In another embodiment, the swing mechanism  80  includes a pivot wheel  81  positioned between the cleaning unit  60  and the offset mechanism  70 . 
     Apparatus  10  includes in one embodiment a lifting device  90  adapted to selectively raise and lower the cleaning assembly  50 . As shown in  FIGS.  3  and  5   , in one embodiment lifting device  90  is affixed by an upper plate  93   a  to the chassis  40 . The device  90  is in one embodiment a parallelogram-shaped framework that can be powered (by motive means not shown, such as e.g. an electric motor, or mechanically) to raise and lower the cleaning assembly  50 . Spaced-apart connecting bars  95   a / 95   b , and  96   a / 96   b  pivotably connect upper plate  93   a  to lower plate  93   b . It can be seen that as the connecting bars and/or lower plate  93   b  are activated to raise lower plate  93   b , in a direction away from the floor, the cleaning assembly is also raised from the floor. Because of the parallelogram configuration of lifting device  90 , the relatively level planar position of cleaning assembly  50 , and in particular cleaning unit  60 , remains essentially the same during raising or lowering by lifting device  90 . 
     Apparatus  10  includes in one embodiment an operator seat  28 , situated between the forward component and the rearward component, and adapted to accommodate a human operator. 
     Apparatus  10  includes in one embodiment a chassis  40  (see  FIG.  2   ) that provides a supporting frame for the housing and other components of the apparatus. 
     Apparatus  10  includes in one embodiment a support plate  73  (see  FIG.  6   ) that serves to support the offset mechanism  70  and swing mechanism  80 , and also supports the underlying cleaning unit  60 . 
       FIGS.  7  and  8    show a top and bottom plan view respectively of a floor cleaning apparatus  10 , with the cleaning unit  60  in an offset cleaning mode, and the apparatus  10  moving in a forward direction. It can be seen that a portion of the cleaning unit  60 , including a portion of cleaning brush  64 , extends beyond the footprint of the floor cleaning apparatus  10 . In the offset cleaning mode as shown, the apparatus  10  is configured to clean edge or floor areas to the lateral right side  21  of the apparatus, e.g. floor areas adjacent a wall that would be difficult or impossible to clean otherwise with the same apparatus in a non-offset position. 
       FIGS.  9  and  10    show a top and bottom plan view respectively of a relevant portion of a floor cleaning apparatus  10 , with the cleaning unit  60  in an offset cleaning mode, and the apparatus  10  turning to the left. As with the apparatus as shown in  FIGS.  7  and  8   , the apparatus  10  is configured to clean edge or other floor areas to the lateral right side  21  of the apparatus  10 . 
       FIGS.  11  and  12    show a top and bottom plan view respectively of a relevant portion of a floor cleaning apparatus  10 , with the cleaning unit  60  in an offset cleaning mode, and the apparatus  10  turning to the right. As with the apparatus as shown in  FIGS.  7  and  8   , the apparatus  10  is configured to clean edge or other floor areas to the lateral right side  21  of the apparatus  10 . 
       FIGS.  13  and  14    show a top and bottom plan view respectively of a floor cleaning apparatus  10 , with the cleaning unit  60  in a non-offset cleaning mode, and the apparatus  10  moving in a forward direction. It can be seen that substantially all of the cleaning unit  60 , except for a portion of edge wheels  52 , is positioned within and underneath the overall footprint of the floor cleaning apparatus  10 . In the non-offset cleaning mode as shown, the apparatus  10  is configured to clean a floor where it is not critical to reach floor areas beyond the footprint of the apparatus  10 , and/or when navigating relatively narrow floor areas, passage ways, and the like, where the lateral extent of the apparatus, including the cleaning unit  60 , is desirably kept to a minimum. 
       FIGS.  15  and  16    show a top and bottom plan view respectively of a relevant portion of a floor cleaning apparatus  10 , with the cleaning unit  60  in a non-offset cleaning mode, and the apparatus  10  turning to the left. As with the apparatus as shown in  FIGS.  13  and  14   , the apparatus  10  is configured to clean a floor where it is not critical to reach floor areas beyond the footprint of the apparatus, and/or when navigating relatively narrow floor areas, passage ways, and the like, where the lateral extent of the apparatus, including the cleaning unit  60 , is desirably kept to a minimum. 
       FIGS.  17  and  18    show a top and bottom plan view respectively of a relevant portion of a floor cleaning apparatus  10 , with the cleaning unit  60  in a non-offset cleaning mode, similar to the embodiment of  FIGS.  15  and  16   , but with the apparatus  10  turning to the right. 
     In each of these cleaning modes and configurations, the cleaning unit  60  has in one embodiment a fixed working width that remains constant whether the apparatus is in an offset mode or non-offset mode. 
     Although in the embodiments illustrated herein, the cleaning unit  60  in the offset position extends beyond the lateral right side  21  of the floor cleaning apparatus  10 , those of skill in the art will appreciate that in an alternative embodiment, the apparatus can be configured such that the cleaning unit in the offset position extends beyond the lateral left side  17  of the floor cleaning apparatus. 
     In an alternative embodiment, the cleaning unit  60  can have a variable working width in an offset mode and/or non-offset mode. 
     The floor cleaning apparatus  10  of the invention can in various embodiments utilize and incorporate various features typical of powered floor cleaning machines. 
     The housing  12  in one embodiment has a rearward component  18  that can include e.g. reservoirs for storing fresh  35  and spent  36  cleaning liquid (depicted, though not explicitly shown in  FIG.  1   ). The housing  12  can also include any of a mechanism (not shown) for dosing and dispensing fresh cleaning liquid onto the floor, and a squeegee/vacuum system  85  for recovering spent cleaning liquid from the floor. In one embodiment, the mechanism for dosing and dispensing can be located in the lower portion of housing  12 , near the floor. In one embodiment, a squeegee/vacuum system  85  is located rearward of the mechanism for dosing and dispensing a cleaning fluid, and rearward of any cleaning brushes  62 ,  64  if present. The housing  12  in one embodiment has a forward component  14  that can be used to house functional elements such as the steering mechanism  29 , and to serve as protection for the operator. 
     The cleaning unit  60  can comprise any device or assembly that affects or treats the floor surface. This can include a mechanism for the cleaning of carpets or hard surfaces of large floor areas, such as in hotels, factories, office buildings, shopping centers and the like. The cleaning unit  60  can include any of a movable body carrying at least one brush; a scrubber, sweeper, or the like. In one embodiment, the cleaning unit  60  includes any of a scrubbing device such as a motor-driven circular or cylindrical scrubbing brush or brushes; reservoirs  35 ,  36  for storing fresh and spent cleaning liquid; a device for dosing and dispensing a fresh cleaning liquid onto the floor, and a squeegee/vacuum system  85  for recovering spent cleaning liquid from the floor. The cleaning unit  60  in one embodiment comprises one or more cleaning implements, such as brushes or scrubbing pads and a motor for driving the implements. 
     In one embodiment, the operator seat is adjustable to enable the operator to adjust the height of the seat to accommodate the height of the operator. 
     In another embodiment, the steering mechanism is adjustable to optimize its location for the benefit and comfort of the operator. 
     In one embodiment, the present invention can be utilized in conjunction with the invention disclosed in U.S. provisional patent application Ser. No. 62/058,733 (Scheiwiller), entitled “Ergonomic Floor Cleaning Apparatus”, filed on Oct. 2, 2014; that application incorporated in its entirety herein by reference. Thus, the present floor cleaning apparatus  10  can be configured such that when the apparatus is in an operative or navigational mode, the human operator is situated on the seat such that the operator is in a partially seated and partially standing position. 
     STATEMENT OF EMBODIMENTS OF THE INVENTION 
     The present application is directed in various embodiments to the subject matter described in the following paragraphs. These are optional embodiments of any of the apparatus and method aspects of the invention as described hereinabove. For each aspect, these features can be incorporated alone or in any suitable combination of these features:
         The cleaning unit has a fixed working width.   The housing comprises a forward component, an intermediate component, and a rearward component.   The floor cleaning apparatus comprises an operator seat.   The floor cleaning apparatus comprises a chassis.   The cleaning unit comprises a brush assembly.   The floor cleaning apparatus comprises a lifting device adapted to selectively raise and lower the cleaning assembly.   The cleaning assembly comprises a support plate that supports any of the offset mechanism, the swing mechanism, and the cleaning unit.   The floor cleaning apparatus comprises any of a motor-driven scrubbing brush, a scrubbing pad, a polisher, a vacuum system, a spray extractor, a reservoir for storing fresh cleaning liquid, a reservoir for storing spent cleaning liquid, a device for dispensing fresh cleaning liquid onto the floor, and a squeegee/vacuum system for recovering spent cleaning liquid from the floor.   The plurality of wheels comprises two front wheels connected with a front axle, and two rear wheels connected with a rear axle, wherein the two front wheels are spaced apart a distance less than the distance between the two rear wheels.   The cleaning assembly comprises a biasing member.   The floor cleaning apparatus is configured such that when the apparatus is in a navigational mode, the human operator is situated on the seat such that the operator is in a partially seated and partially standing position.   When the floor cleaning apparatus is in a navigational mode, the back of the human operator is substantially vertical.   When the floor cleaning apparatus is in a navigational mode, the upper legs of the human operator are sloped downward toward the front end of the floor cleaning apparatus.   When the floor cleaning apparatus is in a navigational mode, the lower legs of the human operator are substantially vertical, or slightly inclined toward the front end of the floor cleaning apparatus.   When the floor cleaning apparatus is in a navigational mode, the human operator is situated at substantially the same height as if the human operator were standing adjacent the floor cleaning apparatus.   When the floor cleaning apparatus is in a navigational mode, the overall position of the human operator is substantially equidistant between the front end and the back end of the apparatus.   When the floor cleaning apparatus is in a navigational mode, the human operator is situated close to or at the longitudinal center of the floor cleaning apparatus.   The cleaning unit comprises a device for polishing the floor.   The cleaning unit comprises a device for vacuuming the floor.       

     Embodiments above have been described in an illustrative manner, and the terminology used is intended to be descriptive rather than limiting. Modifications and variations of the illustrated embodiments are possible in light of the above teachings. Therefore, within the scope of the appended claims, wherein reference numerals are provided merely for convenience and are not to be in any way limiting, the invention may be practiced other than as specifically described in the illustrative embodiments.