Abstract:
The present invention relates to a simple mechanical dual stage pressure control for a cleaning head operatively coupled to a cleaning vehicle for engaging a surface to be cleaned and to methods of engaging and using such a dual stage pressure control to perform surface cleaning, surface maintenance, surface conditioning and the like. While the present invention is described and depicted primarily with reference to a cleaning head having dual rotary scrubbing brushes, the present invention finds diverse application in the art of surface cleaning, maintenance, conditioning and the like. Accordingly, the present invention is readily adaptable to cleaning heads having one or more of the following applications, including without limitation, such cleaning heads designed and adapted to: burnish, polish, scrub, sweep, brush, treat and wipe a surface to be cleaned wherein an increased downforce is beneficially selectively applied to such cleaning head to increase the efficacy of such cleaning head.

Description:
RELATED APPLICATIONS  
       [0001]    This application hereby incorporates by reference and, under 35 U.S.C. §119(e), claims the benefit of priority of U.S. Provisional Patent Application No. 60/302,837, filed Jul. 2, 2001. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The present invention relates generally to surface maintenance or conditioning machines, and particularly those machines employing one or more surface maintenance or conditioning appliances or tools that perform one or more tasks including, among others, scrubbing, sweeping, and polishing or burnishing. More specifically, the present invention is particularly directed to a variable down-force coupling system for such surface conditioning machines.  
         BACKGROUND OF THE INVENTION  
         [0003]    Surface maintenance vehicles that perform a single surface maintenance or surface conditioning task are, of course, well known. Surface maintenance vehicles are generally directed to perform work in diverse maintenance, conditioning and cleaning applications such as for flooring surfaces. In this disclosure, the term floor refers to any support surface, such as, among others, floors, pavements, road surfaces, ship decks, and other surfaces to be cleaned and the like.  
           [0004]    Commonly floor or surface maintenance machines are constructed having a single surface conditioning appliance or system so as to only sweep, others to scrub, while still others only to polish or burnish. It is of course possible to construct a single surface maintenance machine to perform one or more of the aforementioned surface maintenance tasks. One example of a multi-task floor conditioning machine is disclosed in U.S. Pat. No. 3,204,280, entitled “Floor Cleaning &amp; Waxing Machine,” the entire disclosure of which is incorporated by reference herein in its entirety for any and all purposes. Another is disclosed in U.S. Pat. No. 5,483,718, entitled, “Floor Scrubbing Machine Having Impact Energy Absorbtion,” the entire disclosure of which is incorporated be reference herein in its entirety for any and all purposes. Disclosed therein is a forward mounted scrubber assembly that is followed by a squeegee assembly.  
           [0005]    Scrubbing systems are well known in the art. Scrubbing systems commonly include a driver assembly and a rotatable scrubber in the form of a brush, pad, or the like. A control device may be utilized for controlling the degree of scrubbing (typically a function of down-force applied through the scrubber) applied to a floor surface depending upon the type and/or condition of floor surface intended to be scrubbed. The scrubber driver assemblies for scrubbing systems are well known in the art and commonly include one or more rotatable brushes driven by a driver motor affixed to a scrubber head. Scrubber heads of the prior art have been selectively raised and lowered by an actuator coupled to the driver so as to achieve an intended down force or scrubbing pressure of the srub pad against a floor surface. Examples of the latter are taught in U.S. Pat. Nos. 4,757,566, 4,769,271, 5,481,776, 5,615,437, 5,943,724, and 6,163,915, the entire disclosures of which are incorporated by reference herein in its entirety for any and all purposes. Common to some of the control systems of the aforementioned prior art is the employment of a current sensor that monitors the current drawn by the driver motor. In some of the aforementioned systems of the prior art a “pressure sensor” is employed that is representative of the pressure of the scrubber head against the floor. Still others attempt to control torque load on the motor indicated by the sensed motor current.  
         SUMMARY OF THE INVENTION  
         [0006]    The present invention relates to an efficient structure for controlling the down force of a working head in engagement with a surface to be cleaned, maintained, or otherwise conditioned. The invention further relates to a method of engaging and using such a control structure to perform surface cleaning, surface maintenance, surface conditioning and the like. While the present invention is described and depicted primarily with reference to a cleaning head having dual rotary scrubbing brushes, the present invention finds diverse application in the art of surface cleaning, maintenance, conditioning and the like. Accordingly, the present invention is readily adaptable to cleaning heads having one or more of the following applications, including without limitation, such cleaning heads designated and adapted to: burnish, polish, scrub, sweep, brush, treat and wipe a surface to be cleaned wherein an ability to control the downforce of the head is beneficial. Of course, such cleaning head implements or cleaning head appliances may each be provided with an embodiment of the present invention and coupled to a single dedicated surface maintenance vehicle or to more than one such cleaning head coupled to a single vehicle.  
           [0007]    In one embodiment, the invention is particularly applicable to a floor scrubbing machine having a scrub head mounted in front of the machine chassis. The scrub head includes a scrub brush or pad and a scrub driver. A linear actuator is utilized to raise and lower the scrub head relative to the floor surface. The scrub head has a predetermined weight which may be supported by the scrub brush in a first operational mode of use. In the first operational mode of use, the scrub head is floatingly supported by the machine so that the scrub head can follow the contours or undulations of the floor surface. In this mode of operation vertical movement of the scrub head relative to the machine is relatively unconstrained. In a second operational mode of use the floor scrubbing machine additionally engages the linear actuator for use in a second operational mode of use. In the second mode of use, the linear actuator may be engaged to transfer additional force to the scrub head, increasing the down force supported by the scrub pad, and increasing the relative scrubbing work performed by the machine. In the second mode of operation, movement of the scrub head relative to the machine is relatively constrained by the linear actuator  
           [0008]    One aspect of the present invention is the provision of a mechanical system for transferring between the first and second operational modes of use. An operator manipulable element may be utilized to change from the first operational mode of use to the second operational mode of use. An automatic disengagement for returning the machine to the first operational mode of use is also provided by one aspect of the present invention. In one embodiment, the automatic disengagement is in response to the scrub head being raised away from the floor surface toward its transport position.  
           [0009]    The present invention provides several advantages over both prior art and contemporary apparatus for controlling the down force, and hence scrub pressure of a cleaning head coupled to a cleaning machine. The present invention may be implemented without a sophisticated electronic control. As a result the present invention is generally lower cost, easier to maintain and less prone to breakage than prior art (and complex contemporary) cleaning head control mechanisms and algorithms. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]    [0010]FIG. 1 is a side elevation view of a surface maintenance vehicle having a cleaning head coupled to said vehicle and incorporating aspects according to the present invention.  
         [0011]    [0011]FIG. 2 is a perspective view of a portion of the surface maintenance vehicle of FIG. 1.  
         [0012]    [0012]FIG. 3 is a perspective view of portions of the surface maintenace vehicle of FIGS. 1 and 2, shown in an unassembled, exploded view adjacent the frame of a surface maintenance vehicle and wherein coupling between such parts is shown in ghost.  
         [0013]    [0013]FIG. 4 is an side elevation view of a preferred embodiment of a dual-stage bracket according to the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0014]    A floor scrubbing machine which uses the present invention is shown in normal operating position in FIG. 1. The scrubbing machine has two front wheels  12  and two rear caster wheels  14 , and a transaxle  16  providing traction drive to the front wheels. The transaxle and rear casters are attached to a frame  18 , which supports a housing  20 . This housing encloses rechargeable batteries which supply energy to power the machine. It also contains a recovery tank to hold soiled scrub water recovered by a vacuum squeegee  24  from a floor  26  being scrubbed. A hinged lid  28  contains a tank for clean scrubbing solution to be dispensed to the floor and a vacuum fan to lift soiled scrub water from the floor via the squeegee  24  and deposit it in the recovery tank. A control console  30  provides necessary controls for an operator who walks behind the scrubber.  
         [0015]    A scrub head  32  is shown in FIG. 1 in position to scrub the floor  26 . A housing  34  encloses two scrub brushes  36 . The brushes  36  are driven by two electric motors  38 , shown in FIG. 3 but omitted for clarity in FIG. 1. An electric actuator  40  attached between the scrub head  32  and the housing  20  raises the scrub head  32  for transport, lowers it for work, and controls its down pressure on the floor. Additional aspects of the electric actuator  40  and associated mechanical coupling are described in more detail hereinafter.  
         [0016]    The scrub head  32  as illustrated in FIGS.  1 - 3  uses two disk scrub brushes  36  rotating about parallel vertical axes. Alternatively, scrub heads may be made with only one disk scrub brush, or one or more cylindrical brushes rotating about horizontal axes. All of these variations can be applied to this invention. The illustrated scrubber is a relatively small model, controlled by an operator walking behind it. Scrubbers are made in much larger sizes, some of which have the operator riding on them. Again, the invention can be applied to larger machines if the essential elements of the invention are observed. While a scrub head  32  is depicted in FIGS.  1 - 3 , any appliance or tool for providing surface maintenance, surface conditioning, and/or surface cleaning to a surface may be coupled to an associated machine or vehicle in accordance with the present invention.  
         [0017]    [0017]FIG. 2 is a perspective view of a portion of the scrub head  32  and associated coupling structure. The scrub head  32  is attached to the frame  18  by a coupling structure which allows it to be raised and lowered and allows the brushes  36  to conform to undulations in the floor  26 . The scrub head  32  is attached to the frame  18  by lower control arms  42 , guide linkage  46 / 48 / 50 , and electric linear actuator  40  and associated coupling structure, including an upper mount assembly  52  for securing one end of the linear actuator to the housing  20 , and a lower bracket  60  for selectively securing the other end of the linear actuator  40  to the scrub head  32 . Additional aspects of the lower bracket  60  are provided hereinafter. The two lower control arms  42  are attached to the frame  18  and the scrub head housing  34  with pivoted connections at their ends. Two upright arms  70  may be connected to bracket  72 , to make an assembly  46 . This part  46  is pivotally attached to the scrub head housing  34  at  74 . Guide  50  is attached to the front wall of the housing  20 . Guide  50  provides a slot  76  within which roller  48  can move up and down. This slot  76  has an arcuate lower portion which is generally vertical and an upper portion which slopes up and toward the rear. During normal operation roller  48  rides more or less midway in the lower portion of slot  76 , where it moves through the same arc as the front pivots of arms  42  to keep the brushes  36  and scrub head  32  parallel to the floor  26  as the scrub head  32  rises and falls while passing over any undulations in the floor. Two springs  78  are attached between the scrub head housing  34  and the arms  70 . Since the arms  70  are constrained at their upper ends by slot  76  and at their lower ends by pivot  74 , the action of springs  78  is to tend to tilt the forward part of the scrub head upward around pivot  74 . Scrub head  20  is caused to tilt when it is raised to ease access to the components thereof by an operator of vehicle  10 . Additional aspects of the scrub head are disclosed in U.S. Pat. No. 5,483,718, incorporated by reference herein.  
         [0018]    [0018]FIG. 3 is a perspective view of an embodiment of cleaning head  32  of the present invention shown in an unassembled, exploded view adjacent frame  18  and body  20  of surface maintenance vehicle  10  and wherein coupling between such parts is shown in ghost.  
         [0019]    Linear actuator  40  is used to raise the scrub head  32  for transport, lower it for work in a first operational mode, and controls its down pressure on the floor in a second operational mode. Linear actuator assembly  40  preferably is an electric actuator having a leadscrew member  80 . As in known in the art, leadscrew member  80  has a thread set formed thereupon and has a distal end  82  which is movable in response to leadscrew  80  rotation. Additional linear actuators may include hydraulic or hybrid electro-hydraulic devices (not shown). The distal end  82  of leadscrew member  80  has a pin-receiving aperture  84  formed therein. A pin  86  coupled to the aperture  84  may engage dual stage bracket  60  as described herein. As described in more detail herein, pin member  86  also is coupled to a manual transition device  88  which preferably comprises a strap member having a handle for ease of manipulation by an operator of vehicle  10 . The precise sequence of moving pin  86  in elongate pathway of dual stage bracket  60  is later described with respect to FIG. 4.  
         [0020]    A biasing spring member  90  is preferably provided that engages the linear actuator  40 . The biasing spring member  90  provides a force that assists in the placement of pin member  86  in the pathway of dual stage bracket  60 . Biasing spring member  90  assists in the movement of pin member  86  (and thus the distal end  82  of the leadscrew member  80 ) when the scrub head  32  is raised (thus returning the scrub head to a default operational state).  
         [0021]    [0021]FIG. 3 illustrates additional aspects of the upper mount assembly  52  which couples the linear actuator  40  to the housing  20 . Upper mount assembly  52  includes a threaded adjustment device  53  which engages a plate member  55  and a channel member  57 . Channel member  57  is coupled to the linear actuator  40  and the plate member  55  through associated pins  59   a  and  59   b.  The threaded adjustment device  53 , in the illustrated embodiments being a threaded fastener, may be manipulated during manufacturing or subsequent servicing to adjust the relative position of the linear actuator to the housing  20 . An adjustment may be required to select a predetermined amount of down force exerted by the linear actuator  40 . Upper mount assembly  52  is thus adjustable to compensate for manufacturing variances of the linear actuator  40  and housing  20 . Adjustments may be made to the relative position of the linear actuator  40  via threaded adjustment device  53  as required during a servicing procedure.  
         [0022]    Referring now to FIG. 4, the dual stage bracket  60  is attached to the housing  32  by a pair of threaded fasteners  92  disposed through a pair of additional “travel” springs  94 . Dual stage bracket  60  defines a range of positions for the constrained pin  86  (and thus linear actuator  40 ) relative to the scrub head  32 . Dual stage bracket  60  includes a configured aperture having a channel portion  96 , an intermediate detent portion  98 , and a shoulder portion  100 . As illustrated in FIG. 4, discrete pin  86  locations may be defined in dual stage bracket  60 , including, a “floating” position  102  within the channel  96 , a middle or “transition” position  104  proximate to the detent portion  98 , and a “high force” position  106  proximate to the shoulder portion  100 . When the pin  86  is within the channel portion  96  (position  102 ), the scrub head  32  is relatively unconstrained by the linear actuator  40  and can move vertically (to displace pin within channel  96 ) to follow minor undulations in the floor surface  26 . The linear actuator  40  is not under axial load from the scrub head  32 , i.e., the linear actuator  40  does not transfer an axial force to increase the down force of the scrub head  32 . Minor movement of the scrub head  32  causes the pin  86  to deviate (generally vertically) from within channel  96  as depicted by arrows  108 . The machine operating with the pin  86  in position  102  may be characterized as being in a first mode of operation. In the first mode of operation, the scrub brush  36  pressure is a function of the scrub head mass and no additional machine weight is transferred to the scrub head  32 . For general scrubbing operations, the first mode of operation provides generally sufficient performance.  
         [0023]    A second operational mode is defined by the present invention. The machine may be characterized as being in a second, “heavy scrub” mode of operation when the pin  86  is proximate the shoulder portion  100 . When the pin is in position  106 , the scrub head  32  is constrained by the linear actuator  40 . The linear actuator  40  is in direct axial engagement with the scrub head  32  and is able to transfer a force through bracket  60  and travel springs  94  to the scrub head  32  to increase the downward force of the scrub head  32 . In this regard, the linear actuator  40  transfers a portion of the machine weight to the scrub head unit  32  to increase the scrubbing down force and increase the scrubbing action to the floor surface. In the second operational mode, the travel springs  94  are slightly compressed and transfer the additional down force to the scrub head  32 , while providing a range of vertical movement to the scrub head  32  to permit the scrub head  32  to follow the ground surface as in the first mode of operation. FIG. 2 illustrates the machine as being in a second mode of operation. In the second mode of operation, the scrub brush  36  pressure is controlled by the linear actuator  40 . A controller (not shown) may be utilized to provide a variable down force (via variable displacement of the actuator) to the scrub head  32  in the second mode of operation. For aggressive or heavy scrubbing operations, the second mode of operation provides increased scrubbing performance. In a preferred embodiment of the present invention the level of downforce in the first “floating mode” of operation is roughly half the magnitude of the “high force” mode of operation  
         [0024]    The movement of the pin  86  relative to the bracket  60  is controlled, at least in part by an operator manipulable handle  88 . Handle  88  may be accessed via an aperture in the housing  20 . Handle  88  may be grasped by an operator and pulled away from the machine to transition the machine between its first mode of operation into its second mode of operation. An intermediate position  104  of the pin  86  within the dual stage bracket  60  is provided whereby the pin  86  is engaged by a detent portion  98  of the bracket  60 . With the pin  86  engaged by the detent portion  98 , the scrub head  32  can be lowered into engagement with the floor surface with the pin  86  travelling into position  106  adjacent the shoulder portion  100 . Upon raising the scrub head  32  from the work surface after a heavy scrubbing operation, the linear actuator  40  is biased by the spring  90  to return the pin  86  from position  106  to a position proximate to its rear face  110  of bracket  60 , thus returning the machine to its normal operation configuration. As such, an automatic transition occurs between the second “heavy” scrub mode of operation and the first “normal” mode of operation as the scrub head is raised from the floor surface  26 .  
         [0025]    A method of transitioning a scrubber from a first “normal” operating mode to a second “heavy” operating mode comprises the following steps: accessing a scrubber in a first “normal scrub” mode of operation; raising the scrub head  32  away from the floor surface; actuating a strap member  88  so that a pin member  86  coupling cleaning head  32  to the vehicle is displaced into engagement with a detent portion  98 ; and engaging the linear actuator  40  to lower the scrub head  32  toward the floor surface so that the pin  86  is moved into contact with shoulder portion  100 ; and further engaging the linear actuator  40  to transfer additional downforce to the scrub head  32 .  
         [0026]    Additional considerations and alternative embodiments with respect to the present invention may include substituting or eliminating certain components and/or subcomponents of the illustrated embodiment. For example, a first and second magnitude of downforce may be provided that different by a simple integer value of magnitude (i.e., one is double or triple the other) or any fractional difference of downforce. As also noted above, manual actuator or strap member  88  may be disposed adjacent leadscrew member  80  as depicted herein or may be remotely mechanically coupled, or may be electronically actuated locally or remotely by an operator of vehicle  10 . If actuator  40  or strap member  88  is remotely activated additional mechanical (or electronic) means of actuating pin member  86  travel between positions  102  and  106  may be required. With respect to intermediate position  104 , alternative embodiments may dispense with intermediate position  104  entirely and provide for a direct transition from floating position  102  high force position  106  without departing from the spirit and scope of the present invention. While bracket  60  has a path for pin member  86  to navigate between a floating position  102  and high force position  106 , a rotary cam which creates displacement, for example with an offset eccentric portion or offset pin location(s) may be used to perform substantially the same function as dual stage bracket  60  of the present invention.  
         [0027]    Additional advantages and modifications will readily occur to those skilled in the art. The invention in its broader aspects is, therefore, not limited to the specific details, representative apparatus and illustrative examples shown and described. Accordingly, departures from such details may be made without departing from the spirit or scope of the applicant&#39;s general inventive concept.