A turf maintenance machine and method of use thereof, said turf maintenance machine for traversing a turf surface having debris elements and turf fill material disposed thereupon, the machine including a main sweeper brush for engaging the debris elements and the turf fill material and transferring the debris elements and the turf fill material toward a debris hopper, and further including a filter device for receiving the transferred debris elements and the turf fill material, and for separating the debris elements from the turf fill material, wherein the debris elements are captured by the machine for subsequent disposal and the turf fill material is returned to the turf surface as the machine traverses the turf surface.

FIELD OF THE INVENTION  
         [0001]    The present invention relates to turf maintenance equipment and more particularly to turf cleaning and grooming equipment and a method of removing debris from turf. Yet more particularly the present invention relates to a novel artificial turf debris collection machine suitable for use on artificial turf having loose turf fill material, the machine for selectively removing debris elements from the artificial turf surface while returning captured turf fill material to the turf surface.  
         BACKGROUND OF THE INVENTION  
         [0002]    Synthetic or “artificial” grass turf has been developed in order to reduce the expenses of maintaining athletic playing areas, and to increase the durability of the turf surface. Synthetic turf generally involves a carpet-like pile fabric with a flexible backing laid on a compacted substrate, such as crushed stone or other stabilized base material. The pile fabric has upstanding synthetic ribbons representing grass blades extending upwardly from the top surface of the backing. Various formulations for granular resilient fill have been developed, the turf fill material being placed between the upstanding ribbons on the upper surface of the backing. Some prior art systems involve the use of sand or crushed slag particles, together with a resilient foam backing or crumb rubber particles to provide resilience. One such synthetic turf assembly is disclosed in U.S. Pat. No. 5,958,527, the entire disclosure of which is incorporated by reference herein.  
           [0003]    Efficient removal of debris, such as dust, food elements, papers, etc. from the surface of an artificial grass turf surface is desired. The debris may include various sized elements, from dust and small seeds, etc. to larger drink cups and other litter. A typical vacuum-based sweeper machine, such as disclosed in U.S. Pat. No. 5,659,921, is capable of removing debris from the turf surface. However, such a vacuum sweeper machine would also capture some of the loose particulate infill material from the synthetic grass turf. Replacement of an equal amount of the removed infill material would subsequently be required.  
           [0004]    Additionally, some debris found on the artificial turf surface may be somewhat buried beneath the surface and otherwise held by fibers of the turf pile. The sweeping brush of a known sweeping machine may have difficulty dislodging buried or held debris for capture. It would be desirable to pre-condition the turf to dislodge debris within the turf allowing the sweeping brush to engage and throw the debris from the turf surface toward a debris hopper.  
           [0005]    Furthermore, the appearance of synthetic turf surfaces may be changed, in a manner similar to carpet surfaces, by altering the nap or directionality of the turf pile. It would be desirable to provide a uniform directionality to swaths of the turf surface as the maintenance machine traverses the surface. An efficient method of grooming the turf pile nap would thus be desired.  
         SUMMARY OF THE PRESENT INVENTION  
         [0006]    The present invention teaches, enables and discloses an artificial turf surface maintenance machine and a method of removing debris from an artificial turf surface having turf fill material disposed therewithin. Such a machine may be a self-powered machine capable of transport across the turf surface. Elements of a turf surface maintenance machine according to the present invention include a sweeping brush for engaging debris upon the turf surface and for conveying the debris and some of the turf fill material toward a hopper, and a coarse hopper filter for capturing the debris while permitting the collected loose turf fill material to pass and be deposited back onto the turf surface.  
           [0007]    A further aspect of the improved turf machine provides a turf surface preconditioning device for engaging the turf and loosening debris from the turf. The turf surface preconditioning device may be a transverse turf engaging element disposed upon the front of the turf machine. The turf surface preconditioning device may be selectively controlled to vary the amount of engagement of the element with the turf.  
           [0008]    Yet another aspect of the improved turf machine includes a turf surface grooming device for engaging the turf and biasing the turf pile into a predetermined groomed orientation. The turf surface grooming device may include one or more rear mounted brush elements which engage the turf.  
           [0009]    These and other objects, features and advantages will become apparent in light of the following detailed description of the preferred embodiments in connection with the drawings. Those skilled in the relevant art will readily appreciate that these drawings and embodiments are merely illustrative and not intended to limit the true spirit and scope of the invention disclosed, taught and enabled herein. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]    Preferred embodiments of the invention will be described in detail hereinafter with reference to the accompanying drawings, in which like reference numerals refer to like elements throughout.  
         [0011]    [0011]FIG. 1 is an elevational side view of an exemplary self-propelled surface maintenance vehicle employing an embodiment of the turf equipment according to the present invention.  
         [0012]    [0012]FIG. 2 is a perspective view of an exemplary self-propelled surface maintenance machine employing an embodiment of the turf equipment according to the present invention.  
         [0013]    [0013]FIG. 3 is an elevational side view a portion of the machine of FIG. 2.  
         [0014]    [0014]FIG. 4 is an exploded perspective assembly drawing of a turf engagement structure according to present invention.  
         [0015]    [0015]FIG. 5 is an exploded perspective assembly drawing of a debris hopper structure according to present invention.  
         [0016]    [0016]FIG. 6 is an exploded perspective assembly drawing of a turf grooming structure according to present invention. 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0017]    In FIG. 1 a sweeping machine  100  incorporating aspects of the present invention is indicated to have a body indicated generally at  10  and driving wheels  12  and  14 . As is conventional in sweeping machines of this type there may be two forward driving wheels and a single rear wheel, although the invention should not be so limited. There is a rotatable brush  16  which extends transversely across the body of the machine and as illustrated by the arrow  18  will be rotated in a clockwise direction to direct dust and debris forwardly into a debris collection chamber or hopper indicated generally at  20 . There is a ramp  22  which defines the entrance to the debris chamber  20 , with the debris chamber being forward of the brush  16  as is customary in forward throw sweeping machines. Positioned above and slightly forward of the debris chamber  20  is a dust collection chamber  24  having a filter assembly  26  therein, with the filter assembly  26  having a movable shaker  28  mounted thereon. Further details of the sweeper may be shown in U.S. Pat. Nos. 5,303,448 and 5,659,921, the disclosure of each expressly incorporated by reference herein.  
         [0018]    In FIGS. 2 and 3, another embodiment of a walk-behind turf sweeper incorporating aspects of the present invention is indicated. Additional aspects of the sweeper may be shown in U.S. Pat. No. 5,884,353, the disclosure expressly incorporated by reference herein. Like element numerals depict similar elements throughout the drawings.  
         [0019]    The machine  100  of FIG. 1 shown disposed upon a turf surface  30 . Turf surface  30  is an assembly including a plurality of upstanding synthetic fibers or ribbons  32  representing grass blades, and a turf fill material  34  of particulate matter disposed interstitially between the upstanding ribbons  32 . The turf fill material  34  may include sand and rubber particles or granules. The infill material  34  serves to provide a degree of cushion or resiliency to the turf surface  30 . Debris of the turf surface  30  is generally indicated as numeral  36 , though the debris  36  may include elements of various size, shape, texture, and material. Turf surface  30  may also include a natural turf surface of grass having a sand-based or other turf fill material.  
         [0020]    Above and to the rear of the dust collection chamber  24  is a vacuum fan indicated diagrammatically at  42 , with the vacuum fan creating an air flow path indicated by the series of arrows designated at  44 . The air flow includes entrained debris  36  and turf fill material  34 . The air flow path begins directly adjacent the forward throwing sweeping brush  16 , passes through the debris chamber  20 , then through a series of baffles  46  into the dust collection chamber  24 . The air flow path then passes through the filter  26  and exhausts from the vacuum fan as indicated by the arrow  48 . The described dust collection path is conventional in sweeping machines of this type.  
         [0021]    Disposed within the debris chamber  20  are filters  50 ,  52  for capturing debris  36  from the air stream while permitting air-entrained turf fill material  34  to pass through and be directed back toward the surface of the turf  30 . As illustrated in FIG. 5, the filters  50 ,  52  may be secured within the hopper body  20 . The filters  50 ,  52  may include a plurality of screens having different apertures for capturing different sized debris. In the illustrated embodiment of FIGS. 1 through 6, the filters  50 ,  52  include an upper filter  50  and a lower filter  52  each of which are in generally horizontal and parallel alignment relative to the turf surface  30 . Alternative orientations of filters  50 ,  52  may also be practicable. A filter shaker (not illustrated) may also be utilized to facilitate the entrained material filter process. The filters  50 ,  52  may include wire screen elements, perforated metal plates, or expanded metal screen materials. Alternative filtering devices may also be utilized provided that the devices permit the passage of the turf fill material  34  while capturing debris  36  from the turf surface  30 . In the illustrated embodiment of FIGS. 1 through 6, a wire screen having a mesh size of 5×0.047 inch has found particular utility for the lower filter  52 . The upper filter  50  includes a slightly larger aperture size compared to the lower filter  52  to capture larger debris elements  36  and prevent the smaller apertures of the lower filter  52  from becoming clogged with debris  36 .  
         [0022]    Referring to FIGS. 1 and 4, the machine  100  further includes a turf engaging structure  60  disposed forwardly from the sweeping brush  16  for preconditioning the turf. The structure  60  engages the turf and facilitates loosening of debris  36  from the turf. During turf engagement by the structure  60 , some debris  36  may be ejected from the turf surface  30  and directed rearwardly toward the brush  16 . Other debris may be lifted or loosened from the turf surface  30  by the turf engaging structure  60  and be subsequently removed from the turf by the brush  16 . The turf engaging structure  60  includes a generally planar turf engaging element  62  which may be selectively adjusted to vary the contact between the element  62  and the turf  30 . As illustrated in FIG. 4, the turf engaging structure  60  includes a pair of frame elements  64  rigidly coupled to the machine  100 , a movable carriage  66  disposed between the frame elements  64 , and a turf engaging element  62  coupled to the movable carriage  66 . The movable carriage  66  is pivotable with respect to the machine  100  along pivot axis  70 . The movable carriage  66  may be selectively positioned relative to the machine  100  by selectively coupling the movable carriage  66  to the frame elements  64  via one of a series of alignment apertures  72  of the movable carriage  66 . The turf engaging plate element  62  is coupled to the movable carriage  66  by threaded fasteners and a plate retainer  74 . A bumper  76  is further provided upon the turf engaging structure  60 . The turf engaging element  62 , illustrated as a single planar element, may assume alternative configurations, including but not limited to multiple plate elements in both transverse and longitudinal application, diverse edge configurations, and different materials including static electricity reducing compositions.  
         [0023]    Referring now to FIGS. 1 and 6, an improved turf machine  100  includes a turf surface grooming device  80  for engaging the turf and biasing the turf pile into a predetermined groomed orientation (into the direction of machine travel). The turf surface grooming device  80  may include one or more brush elements, which may be powered or stationary brushes (relative to the machine  100 ). The turf surface grooming device  80  may also include a towed structure, including mesh or screen elements (not shown), for biasing the turf pile. In a preferred embodiment, the turf surface grooming device  80  is a stationary brush structure movably coupled to the rear of the machine  100 . The turf surface grooming device  80  may include a plurality of rear mounted brush elements  82  which engage the turf pile and provide a directional nap to the engaged turf swath. The brush elements  82  are movably coupled to the machine  100  via an attachment structure  84 . The attachment structure  84  may be controlled via linkages  86  to vary the amount of down force transferred to the brush elements  82 . Alternative attachment structures  84  would be appreciated by those skilled in the relevant arts.  
         [0024]    In operation, the machine  100  traverses the debris littered turf surface  30  under control of an operator. During movement of the machine, the turf surface  30  is initially engaged by the turf engaging device  60 , which preconditions the turf surface  30  by lifting and/or loosening debris  36  upon the turf. The degree of turf engagement may be varied (depending on the turf type, debris type, or other conditions) by manipulating the relative position of the turf engaging element  62  relative to the machine  100 . The turf surface  30  is next engaged by sweeping brush  16  which contacts and throws the debris  36  and some turf fill material  34  forwardly and upwardly into the hopper  20 . The sweeping brush  16  preferably engages only the top portion of the turf surface  30 , i.e., a relatively light sweep is required to contact and throw debris from the turf. The mixture of debris  36  and turf fill material  34  is processed by the filters  50 ,  52 , which capture larger elements of debris  36  while permitting the passage of the turf fill material  34  back onto the turf surface  30 , shown generally as numeral  90 . The turf surface  30  is finally engaged by the grooming device brushes  82  which bias some substantial portion of the turf pile into the direction of movement, the groomed turf shown generally as numeral  92 . The result of the grooming device  82  is to improve the aesthetic of the turf surface  30 , e.g. to provide a “just mowed” look to the turf surface  30 .  
         [0025]    Additional advantages and modifications will readily occur to those skilled in the art upon reflection on the teaching, written disclosure and illustrations herein. 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's general inventive concept.