Abstract:
An improved suspension system for coupling a surface maintenance tool or appliance to a surface maintenance machine is disclosed. In preferred embodiment, the suspension system includes a 4 bar linkage which permits the surface maintenance tool to be raised and lowered relative to the surface maintenance machine into selective contact with the floor surface, a spring assembly transferring spring force to the surface maintenance tool, and a selectively controllable actuator connected to the spring assembly for controlling a level of the spring force so that a controlled level of surface maintenance tool work is performed upon the floor surface.

Description:
RELATED APPLICATION  
       [0001]    This application claims the benefit of priority of U.S. Provisional Patent Application No. 60/292,675, filed on May 21, 2001, the disclosure of said application being incorporated by reference herein. 
     
    
     
       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. The more specifically, the present invention is particularly directed to a suspension system for a surface maintenance appliance, and specifically a burnishing assembly.  
         BACKGROUND OF THE INVENTION  
         [0003]    Surface maintenance machines that perform a single surface maintenance or surface conditioning task are, of course, well known. Surface maintenance machines are generally directed to applications such as floor surfaces, or simply floors. The term floor, as used herein, refers to any support surface, such as, among others, floors, pavements, road surfaces, ship decks, 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.  
           [0005]    One example of a multi-task floor conditioning machine is disclosed in the U.S. Pat. No. 3,204,280, entitled, “Floor Cleaning &amp; Waxing Machine,” issued to Campbell, the enter disclosure of which is incorporated by reference herein in its entirety for any and all purposes. Another is disclosed in U.S. Pat. No. 4,492,002, entitled, “Floor Cleaning Machine,” by inventors Waldhauser, et al, the entire disclosure of which is incorporated by reference herein in its entirety for any and all purposes. Disclosed therein is a forward sweeper assembly followed by a scrubber assembly that is followed by a squeegee assembly.  
           [0006]    Yet, another example of a multi-task floor conditioning machine is disclosed in a PCT application having publication WO 00/74549, published Dec. 14, 2000, entitled, “Floor Cleaning Machine,” by inventors Thomas, et al, the entire disclosure of which is incorporated by reference herein in its entirety for any and all purposes. The machine disclosed therein performs the task of sweeping, scrubbing, and burnishing, and includes a squeegee assembly in combination with a vacuum system for removing cleaning solution from a floor subsequent to a cleaning and scrubbing operation.  
           [0007]    As illustrated in WO 00/74549, thereshown is a single unitary walk-behind machine that is transportable across a floor. Successively attached to the machine, from front to back, are independent floor maintenance systems. At the forward section of the machine is a sweeping system. At the rearward section of the machine—machine steering control—is a burnishing system. In between the sweeping system and the burnishing system is a scrubbing system including forward scrubbing brushes coupled to a cleaning solution dispensing system and rearward following squeegees coupled to a liquid vacuum system for recovering expended cleaning solution.  
           [0008]    Burnishing systems generally include a scheme for controlling the degree of burnishing applied to a floor surface depending upon the type of floor surface intended to be burnished. Burnishing systems well known in the art commonly include a driver assembly which includes a working appliance or tool such as a pad or brush affixed to a driver that is rotatably driven by a driver motor. The driver assembly of the burnishing systems of the prior art have been selectively raised and lowered by an actuator so as to achieve an intended force or pressure against a floor surface intended to be polished or burnished.  
           [0009]    Scrubbing systems are analogous to burnishing systems, and are also well known in the art. Scrubbing systems commonly include a driver assembly including rotatable scrubber in the form of a brush, pad, or the like, and a scheme for controlling the degree of scrubbing applied to a floor surface depending upon the type of floor surface intended to be scrubbed. Too much scrubbing of course may deleteriously affect the floor surface requiring further maintenance. The scrubber driver assemblies for scrubbing systems, like burnishing systems, are of course 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 force or pressure of the brush against a floor surface intended to be scrubbed. 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.  
           [0010]    Common to some control systems of the aforementioned prior art patents 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.  
           [0011]    Sweeper systems are also analogous to burnishing systems. Sweeper systems commonly include a rotatable sweeper system brush driven by a driver motor. Like burnishing and scrubbing systems the sweeper system brush may be lowered and raised relative to a floor, which may more or less affect the floor surface.  
           [0012]    Commonly, floor conditioning machines are powered by a rechargeable battery supply. Of course, the battery voltage applied to the various floor conditioning systems or appliances, and particularly to the driver motor, will decay in relation to the energy discharged by the battery and the total time of discharge. With respect to burnishing systems, the mechanical burnishing power delivered to the floor is therefore dependent upon the voltage and current delivered to the driver motor.  
           [0013]    Burnishing appliances or systems on such floor maintenance machines have several factors that place design demands on the suspension system from the floor maintenance machine that are suspended. This is so since commonly the burnishing pad is somewhat surrounded in part by peripheral portion of the driver and is surrounded by an attached skirt extending from peripheral portions of the driver—the skirt preventing dust and debris from being injected into the environment. In operation, upon powering of the burnishing assembly driver motor, a vacuum is established within the chamber formed by the burnishing system driver and skirt. This in turn causes a vacuum which tends to pull the burnishing assembly toward the floor. This vacuum may be controlled by way of providing breather vents or ports in the skirt.  
           [0014]    It should be understood that as the burnishing assembly suspended from the frame of a floor maintenance machine is pulled toward the floor by the aforesaid vacuum greater load upon the driver motor results as well increased working power or force against the floor results, the magnitude of which is dependent upon the type of floor surface intended to be burnished or polished. Driver motor load current controllers known in the prior art burnishing systems or scrubber systems, may of course be employed to more or less yield substantially controlled working power or force against the floor surface, as well as prevent drive motor burn out.  
         SUMMARY OF THE INVENTION  
         [0015]    An object of the present invention is to provide a suspension system for a floor maintenance appliance suspended from a frame associated with a floor maintenance machine.  
           [0016]    An object of the present invention is to provide a suspension system for burnishing appliance or assembly suspended from a frame associated with a floor maintenance machine.  
           [0017]    A variable load suspension system has been disclosed for varying the work force of a surface maintenance appliance upon a surface intended to be affected. In one exemplary embodiment, a series combination of an actuator and a spring assembly is coupled to a frame at one end, and the other end thereof is coupled to the surface maintenance appliance by way of an appropriate linkage. In the preferred embodiment of the invention, the spring assembly, and specifically the spring, generally extends in the direction of transport of the surface maintenance machine  10 , and the actuator causes motion transverse to the surface intended to be affected.  
           [0018]    The actuator and driver motor of the surface maintenance appliance are intended to be controlled by any of the aforementioned control systems known in the art as well as others without departing from the true spirit and scope of the present invention. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0019]    [0019]FIG. 1 is a side view of a walk behind surface maintenance machine employing a suspension system in accordance with the present invention for suspending a burnishing system.  
         [0020]    [0020]FIG. 2 is a partial perspective view of the suspension system assembly in accordance with the present invention.  
         [0021]    [0021]FIG. 3 is a side view showing further details of the suspension system assembly illustrated in FIG. 2.  
         [0022]    [0022]FIG. 4 is top plan view illustrating suspension system components in accordance with the present invention.  
         [0023]    [0023]FIG. 5 is a schematic block diagram of an exemplary embodiment of a control system for a floor maintenance appliance for controlling the work output delivered to a floor surface. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0024]    Illustrated in FIG. 1 is walk behind surface conditioning machine  10  in accordance with the present invention. A burnishing assembly generally indicated by numeral  100  is suspended from a frame  20  by way of a suspension system assembly in accordance with the present invention generally indicated by numeral  200 , and particularly illustrated in FIG. 2 as will be described in further detail herein. FIG. 1 graphically depicts the available range of motion of the burnishing head or assembly  100  when coupled to the frame in accordance with the present invention. Namely, a transport position  101 , lowered operating position  102 , and pad changing position  103 .  
         [0025]    Illustrated in FIG. 2 is a perspective view of the suspension system  200  in accordance with the present invention. In FIG. 2, burnishing assembly  100  has been omitted. Suspension system  200  includes an actuator  220  pivotally coupled to frame  20  through coupling member  224 , and having an actuator rod  222  pivotally coupled to a spring assembly  400  (not shown in FIG. 2, shown in FIG. 4). Spring assembly  400  is coupled to a 4-point or four parallel bar linkage system  215  through coupling brackets  250 L and  250 R.  
         [0026]    A pair of mounting bracket  210 L and  210 R is intended to be rigidly attached to the burnishing assembly driver member  110  upon which a driver motor is generally mounted.  
         [0027]    Burnishing assembly  100  is coupled to frame  20  by way of the 4-point or 4-bar linkage  215  including bars  230 L,  230 R,  240 L, and  240 R. Ends  232 L,  232 R,  242 L, and  242 R are pivotally coupled to frame  20  (not shown) by way rotatable mounted pins, bolts, or the like mounted through apertures  234 L,  234 R,  244 L, and  244 R, respectively. The four point linkage system is of course well known for generally lifting and lowering an assembly with generally transverse movement relative to the ground plane upon which the assembly may rest. In other words, permits vertical movement while fixed in a lateral position relative to a reference frame, namely the frame  20  of the surface maintenance machine  10 .  
         [0028]    Suspension coupling bracket  250 L has a first end  252 L rigidly secured to bar  240 L by way mounting bolts  253 , welding, or the like. The other end of bracket  250 L is pivotally coupled to one end of spring assembly  400  as will subsequently be described in detail below. Similarly, bracket  250 R has a first end  252 R rigidly secured to bar  240 R by way mounting bolts  253  (not shown) or the like. The other end of bracket  250 R is also pivotally coupled to one end  410  of spring assembly  400 , and is substantially identical to suspension coupling bracket  250 L but is substantially hidden from view in the figures.  
         [0029]    Spring assembly  400  is further described in FIG. 4. As illustrated in FIG. 4, spring assembly is essentially a preloaded draw spring well known in the art having a helical spring housing  420  enclosing, in part, helical spring  410  with rod  430  passing therethrough. One end  423  of housing  420  is pivotally coupled to actuator rod  222 . The opposite end of rod  430  is affixed to pin assembly member  440  by way of a threaded bolt  443 , or the like. One end of spring  410  is coupled to an anti-rotation plate  445  having extending tabs  447  protruding through slots  446  of housing  420 . The other end of spring  410  engages housing end member  441  of housing  420  through which rod  430  passes therethrough.  
         [0030]    Pin assembly member  440  includes a pair of pins or rod shape members  43  IL and  43  IR intended to be pivotally coupled to suspension coupling bracket end members  253 L and  253 R of suspension coupling brackets  250 L and  250 R, respectively. As illustrated in the figures, rod shaped members  431  pass through, in part, arcuate slots  255 L ( 255 R not shown). These slots may be omitted as their function provides for obtaining the appliance assembly position identified as numeral  103  in FIG. 1 while maintaining pivotal coupling. It should also be noted that suspension coupling brackets  250 L and  250 R are somewhat “s-shaped” so as to permit unobstructed movement of the 4-point suspension system, while at the same time permit 4-point suspension system to be affected, in part, by the combination spring assembly  400  and actuator  220 .  
         [0031]    Actuator  220  includes a mounting member  224  for pivotally coupling actuator  220  to frame  20 . Similarly end member  223  of actuator rod  222  is pivotally coupled to housing end member  423  by way of any suitable pivotal coupling, for example a travis pin assembly or the like as indicated by numeral  425 .  
         [0032]    In an exemplary embodiment of the invention, draw spring assembly may have a free length spring of 29 inches, an installed length of 15 inches (compressed spring) with a 20 lbs.-inch rate of spring force. It is of course should be understood by those skilled in the art that the size of draw spring assembly  400  may be embodied by way of a wide array of physical sizes depending upon the weight of the burnishing assembly, and the available room and cost considerations associated with the surface maintenance machine  10 .  
         [0033]    In operation of the suspension system of the present invention, in the actuator retracted position, the burnishing assembly is the machine transport position indicated by numeral  101  in FIG. 1 and the assembly is away from the floor surface.  
         [0034]    In the “operate position,” the actuator is extended a predetermined amount until the burnishing head makes contact with the floor surface while under the influence of the draw spring assembly  400 . In turn the actuator  220  and burnishing head driver  110  motor may be controlled to achieve regulated work force upon the surface intended to be affected. Actuator  220  is selectively controlled during operation to adjust the degree of spring compression, and hence the degree of spring force transferred by spring assembly  400  to burnishing assembly  100 . Actuator  220  may be a hydraulic actuator (not shown) or other known actuation device appreciated by those skilled in the relevant arts.  
         [0035]    The present invention provides a horizontal packaging technique for achieving variable spring load in the vertical direction of a surface maintenance assembly or appliance, for example burnishing, scrubbing, waxing assemblies, and the like.  
         [0036]    A variable load suspension system has been disclosed for varying the work force of a surface maintenance appliance upon a surface. A series combination of an actuator and a spring assembly is coupled to a frame at one end, and the other end thereof is coupled to the surface maintenance appliance by way of an appropriate linkage. In the preferred embodiment of the invention, the spring assembly  400  generally extends in the direction of transport of the surface maintenance machine  10  (generally parallel with the surface), and the actuator causes motion transverse to the surface intended to be affected.  
         [0037]    It should be recognized that alternatively, the positions of actuator  220  and draw spring assembly  400  could be interchanged as should be recognized by those skilled in the art.  
         [0038]    In accordance with another aspects of the present invention, brackets  210 L and  210 R are provided with arcuate slots  577  whereby pins coupling bar members  230 L and  230 R may be lifted upward from points  213 L and  213 R. With the arcuate slots  577  and corresponding slots  255 L and  255 R in coupling brackets  250 L and  250 R respectively, the entire mechanism may be lifted. Locking members  280 L and  280 R are provided with a slot so that bar members  250 L and  250 R may be pivotally coupled to members  280 L and  289 , respectively, permitting the assembly  100  to be raised to pad changing position as indicated by numeral  103  in FIG. 1.  
         [0039]    Referring to FIG. 5, a schematic block diagram is illustrated representing one exemplary embodiment of a control system for a floor maintenance appliance that controls the work output delivered to a floor by a rotatable work tool, such as a polishing pad, a scrubber, a brush, etc. Such a control system may be utilized in conjunction with embodiments of the present invention to control linear actuator  220 . Additional aspects of this control system are disclosed in U.S. patent application Ser. No. ______, filed on May 21, 2002, entitled “Control System for a Floor Maintenance Appliance,” having a common assignee with the present application, and being incorporated in its entirety by reference herein. In FIG. 5, a floor maintenance assembly  10  is configured as a burnishing system suspended from a frame  22  associated with a floor maintenance machine (not shown) by way of an actuator  20 . The actuator  20  is configured to raise and lower the maintenance assembly  10  relative to the floor  24 . Although a burnishing tool is illustrated in the Figures, it should be understood that the maintenance assembly  10  may be configured to perform other types of maintenance tasks, such as sweeping and scrubbing, or a combination of maintenance tasks. As shown in FIG. 5, the maintenance assembly  10  includes a rotatable driver  12  having a rotatable shaft  14  coupled to a driver motor  16 . The rotatable work tool for performing the work task is a burnishing pad  18  that is coupled to a rotatable driver  12 . The maintenance assembly  10  and the actuator  20  may be implemented by way of a wide array of components and techniques, many of which have been described in the aforementioned published patents and publications, among others.  
         [0040]    Although the present invention and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the disclosure of the present invention, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present invention. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.