Abstract:
Powered turf conditioning brushes having increased efficiency, improved lift, and which minimize the introduction of grain, and their method of use with reel mower cutting units such as those used for precision mowing of golf course greens. Various embodiments are disclosed.

Description:
[0001]    This application is a continuation of U.S. Non-provisional application Ser. No. 13/071,268, filed Mar. 24, 2011, which claims benefit to U.S. Provisional Application Ser. No. 61/317,051, filed Mar. 24, 2010. Each patent application identified above is incorporated here by reference in its entirety to provide continuity of disclosure. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    Proper grooming of golf course greens seeks to maintain consistent playability of the grass surface, and to eliminate “grain,” texture in the green that can bias the roll of the golf ball. If the leaves of grass in the green are oriented in a particular direction, such as can naturally occur in response to the direction of sunlight, balls hit in the direction the grass is leaning, or “with the grain,” face less resistance to their rolling than balls hit in the reverse direction, or “against the grain.” Grooming the grass in the green to stand straight involves maintaining precise cutting height and reducing to the greatest extent any factors which would introduce a non-vertical orientation of the grass leaves. 
         [0003]    The design of modern reel mower cutting units utilizes a powered reel of several helical blades which rotate in close contact with a fixed bedknife to clip the grass leaves to a uniform height in a scissor like fashion. The number of blades in a cutting reel varies, with more blades providing a greater “clip frequency” over a given distance of the reel mower cutting unit&#39;s forward travel. The cutting reel and bedknife are generally mounted between two ground-contacting rollers in a frame that permits the height of cut to be adjusted precisely. In walk-behind reel mowers, the rear roller, also called the traction roller, is powered, and the front roller is generally used to adjust the cutting height. In current walk-behind designs, the cutting reel is either mechanically linked to the engine and drivetrain powering the rear traction roller, or is powered by an electric motor which permits the clip frequency of the cutting reel to be set independent of the engine&#39;s throttle setting and speed of ground travel, an arrangement termed a “hybrid” drive. 
         [0004]    In ride-on reel mowers, one or more powered helical reel cutting units is pushed or pulled across the grass surface by a tractor, with each cutting unit mounted on its own ground-contacting rollers in a manner that permits the cutting units to individually adjust to the contours of the ground. Hybrid drive systems are also available for the cutting units of ride-on reel mowers. 
         [0005]    Powered rotating brushes are known which may be used to keep the ground-contacting rollers of the reel mower free of grass clippings, which could otherwise adhere to the rollers and change their effective diameter, resulting in a change in the height of the cut. For example, uneven cutting could result from clumps of grass clippings adhering to the rollers, producing “bumpy” or “washboard” greens. 
         [0006]    It is also known in the art to provide a mechanical means for conditioning the grass leaves prior to cutting, generally through the use of a rotating powered brush or set of rotating vertical dethatching blades located between the front roller of a reel mower cutting unit and the helical cutting reel. Many reel mower cutting units have a groomer drive accessory configured to power such turf conditioning attachments. Such conditioning means are intended to take advantage of the natural plasticity of the grass leaves in order to temporarily re-orient them in a more vertical direction immediately prior to cutting. Changing the orientation of the grass leaves, such as through brushing, increases cutting effectiveness by helping to ensure that grass leaves do not pass below the blades of the cutting reel and thus escape cutting. Mechanically conditioning the grass prior to cutting can, with repeated application, also train the grass leaves in the green to a more upright growth habit. 
         [0007]    Existing mechanical means for conditioning the grass prior to cutting are, however, inefficient for their intended purpose, and can introduce “grain” and other problems into the reel mowing process. Existing conditioning means which use rotating dethatching blades provide little “lift” to the grass, because the blades are intended primarily to cut the stolons connecting individual grass plants, rather than re-orient the grass leaves. Existing powered brushes for conditioning the grass prior to cutting are also inefficient, and their design can introduce grain, by “augering” the leaves of the grass preferentially in one direction. 
         [0008]    Earlier designs for powered brushes having continuously bristled surfaces were less effective at penetrating the grass canopy, and earlier powered brushes having discrete tufts of long bristles used too few rows of tufts for optimum effectiveness, and the long bristles tended to flex too much and wear out faster. Other techniques, such as the use of separate grooming equipment prior to mowing do not address the compaction of the turf and compression of grass leaves caused by the front roller of the reel mower cutting unit, and a delay between grooming the turf and mowing permits the grass leaves time to relax prior to cutting. 
         [0009]    A need therefore exists in the art for an improved powered turf conditioning brush for conditioning the grass prior to cutting that provides increased efficiency, improved lift, and which minimizes the introduction of grain. 
       SUMMARY OF THE INVENTION 
       [0010]    The present invention may be embodied in an improved turf conditioning brush suitable for use with reel mower cutting units, such as those used for precision mowing of golf course greens. 
         [0011]    The turf conditioning method and apparatus described herein provides a powered rotary brush that may be mounted on a reel mower cutting unit, transversely to the direction of travel, between the front ground-contacting roller and cutting reel, such as within the groomer drive accessory, and may be configured to be adjustable in elevation above the surface of the turf in order to vary the amount of contact of the brush with the turf and to permit adjustment for wear of the brush. 
         [0012]    Depending upon the condition of the turf, it may be desired to adjust the height of the brush to apply a greater or lesser brushing intensity or “aggressiveness” of turf conditioning prior to cutting, and as described herein, the method and system may comprise turf conditioning brushes having different degrees of bristle stiffness suitable for various turf conditions and types of grass, the bristle stiffness being determined primarily by the bristle diameter and the material or materials from which the bristles are made. 
         [0013]    A turf conditioning brush constructed according to one embodiment has a generally cylindrical base that is configured to rotate by one of several means, including, but not limited to, being configured as a sleeve rotatably mounted on an axle, a sleeve engaging a rotatable spindle, or the base may be constructed integrally to a rotatable spindle. Motive force for the rotation of the sleeve or spindle may be supplied by any of several means, including, but not limited to, indirect means such as a geartrain, a drive belt engaging a pulley, a drive chain engaging a sprocket, or the sleeve or spindle may be directly driven. In an example embodiment, the brush base is configured as a sleeve engaging a rotatable spindle. The direction of rotation of the brush base may be the same as that of the cutting reel or opposite to that of the cutting reel, and in one embodiment the rotation of the brush base is opposite to that of the cutting reel, such that the grass-contacting face of the brush is rotating towards the oncoming grass leaves and away from the cutting reel when the reel mower cutting unit is in forward motion. 
         [0014]    According to one embodiment, a plurality of bristle tufts are attached radially to the brush base in a number of parallel rows along the width of the brush base, with the centers of the bristle tufts in each row spaced equally apart from each other, and the centers of the bristle tufts in each row offset from those in adjacent rows by an offset value that is the ratio of the distance that the bristle tufts in each row are spaced apart divided by an offset factor that is a divisor of the number of parallel rows. In addition to selecting brushes having different degrees of bristle stiffness as described above, one skilled in the art may also select brushes having different tuft spacing values and tuft offset values as desired based upon the turf conditions or type of grass to be mowed. 
         [0015]    Having the bristle tufts spaced apart and offset from each other in accordance with the present disclosure improves brushing efficiency in comparison to a brush having a continuously bristled surface, by enabling the bristle tufts to better penetrate the leaf canopy of the turf. Additionally, the generally symmetrical arrangement of tufts provided by the present disclosure does not produce an augering effect that may introduce “grain” into the turf. A turf conditioning brush constructed according to the present disclosure therefore provides an improved lifting action over the prior art. 
         [0016]    These and other objects, features and advantages of the invention will be further described and more readily apparent from a review of the detailed description of the embodiments which follow. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]      FIG. 1  is a perspective view of a turf conditioning brush according to an embodiment of the invention. 
           [0018]      FIG. 2  is a partial detail perspective view of a turf conditioning brush according to an embodiment of the invention, illustrating the tuft pattern. 
           [0019]      FIG. 3  is a perspective view of a turf conditioning brush according to an embodiment of the invention. 
           [0020]      FIG. 4  is a partial detail perspective view of a turf conditioning brush according to an embodiment of the invention, illustrating the tuft pattern. 
           [0021]      FIG. 5  is a perspective view of a turf conditioning brush according to an embodiment of the invention, showing the brush mounted to a drive spindle. 
           [0022]      FIG. 6  is a detail perspective view of one end of a turf conditioning brush according to an embodiment of the invention. 
           [0023]      FIG. 7  is a perspective view of a ride-on reel mower. 
           [0024]      FIG. 8  is a partially exploded view of a turf conditioning brush and a reel mower cutting unit. 
           [0025]      FIG. 9  is a perspective view of a turf conditioning brush and a reel mower cutting unit, where the turf conditioning brush is mounted within the groomer drive accessory of the reel mower cutting unit. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0026]    As shown in  FIGS. 1-6 , in one embodiment, a plurality of bristle tufts  200  are attached radially to a generally cylindrical brush base  100  in a predetermined number of parallel rows along the width of the brush base  100 , with the centers of the bristle tufts  200  in each row spaced equally apart from each other in a symmetrical fashion, and the centers of the bristle tufts  200  in each row offset from those in adjacent rows by an offset value that is the ratio of the distance that the bristle tufts  200  in each row are spaced apart divided by an offset factor that is a divisor of the number of parallel rows. Such arrangement of the bristle tufts on brush base  100  produce a desired lifting effect. Other arrangements of the bristle tufts on brush base  100  may be used as desired by one skilled in the art to produce such desired lifting effect. 
         [0027]    In contrast with brushes having an arrangement of bristle tufts which may produce an undesirable “augering” effect which can introduce “grain” into a green, brushes having bristle tufts which are mounted radially in parallel rows along the width of the brush base produce a lifting effect that is aligned with the direction of travel of the mower. Considering the “contact patch” of the brush, which is the portion of the brush in contact with the turf at a given time, the parallel rows of bristle tufts encounter the grass canopy straight on, and lift the grass leaves vertically more efficiently. The efficiency of a turf conditioning brush having parallel rows of bristle tufts along the width of the brush base may be further augmented by increasing the absolute “brush frequency” or Fa, defined as the number of times per rotation a given spot in the contact patch of the brush would be touched by a bristle tuft if the brush were rotating but not moving forward. The effective “brush frequency” or Fe, derives from the absolute brush frequency, but takes account of the mower&#39;s forward motion. The forward motion of the mower effectively reduces the brush frequency because a given spot in the turf generally will not remain within the contact patch of the brush for very long. 
         [0028]    The use of a hybrid drivetrain that permits the rotation speed of the groomer drive and cutting reel to be adjusted independently of the throttle and traction drive can serve to compensate for a lower effective brush frequency to some degree, but providing a brush having a higher absolute brush frequency will benefit both hybrid and non-hybrid driven reel mowers, by allowing the operator to be assured of effective brushing and lift even while mowing at higher speeds of forward travel. 
         [0029]    As shown in  FIGS. 1-4 , the brush base  100  has a predetermined width (designated W) and radius (designated R). The radius R of the brush base is one practical limit of the number of rows (designated N) of bristle tufts on a turf conditioning brush that may be accommodated in the available space within the groomer drive of a reel mower cutting unit. Generally, brush bases having a larger radius R will accommodate a greater number of rows N of bristle tufts  200 . Brushes having a larger base radius R are generally desirable because the larger base radius makes possible an increase in N that enables an increased absolute brush frequency, and a larger, and locally flatter, contact patch area which increases the effective brush frequency. In one embodiment, N is equal to  12 . 
         [0030]    Just as a larger number of helical blades in a cutting reel results in a greater “clip frequency” for the reel, the greater the number of tuft rows N in the brush, the higher the effective “brush frequency” can be for a given rate of brush rotation and mower forward travel. However, brushes which present a contact patch that is a continuously bristled surface are undesirable due to their bristle tufts not being able to effectively penetrate the grass canopy. Spacing between the rows of bristle tufts and between the bristle tufts in the same row is necessary to ensure effective penetration of the canopy and to produce the desired lifting effect that re-orients the grass leaves in a more vertical direction. In one embodiment, the bristle tufts in adjacent rows may be offset, because spacing the bristle tufts of adjacent rows in line with each other around the circumference of the brush base would produce gaps where the absolute and effective brush frequency would be zero. Offsetting the centers of the bristle tufts in adjacent rows by an offset value that is the ratio of the tuft spacing distance divided by an offset factor that is a divisor of the number of parallel rows N, produces a contact patch having a uniform absolute brush frequency that is N divided by the offset factor. 
         [0031]    For example, as illustrated in  FIGS. 1 and 2 , in a brush having twelve rows of bristle tufts, an absolute brush frequency of six can be achieved with a tuft offset of ½ the tuft spacing distance. As illustrated in  FIGS. 3 and 4 , another embodiment of the present invention, in a brush having twelve rows of bristle tufts, an absolute brush frequency of four can also be achieved by using a tuft offset that is ⅓ the tuft spacing distance. The slight degree of asymmetry of the tuft pattern that results from using a tuft offset factor of three rather than two does not produce appreciable “grain.” For a brush having fifteen rows of bristle tufts, an offset factor of three would make it possible to achieve an absolute brush frequency of five, though the implementation of brushes with fifteen rows, or even larger values of N, will likely require redesign of the groomer drive accessory of existing reel mowers to accommodate brushes having an increased base radius. 
         [0032]    In accordance with an exemplary embodiment, N may be a value between 8 and 16, and the rows of bristle tufts  200  arranged radially around the brush base  100  at an angle of 360/N degrees relative to each other, as depicted in  FIG. 6 . The brush base  100  may be made of any suitable strong, rigid material, such as plastic, metal, or composite materials, and in a preferred embodiment is made of acrylonitrile butadiene styrene (ABS) plastic. 
         [0033]    As shown in detail in FIGS,  2  and  4 , each bristle tuft  200  comprises a plurality of bristles  210 , with each bristle  210  having a predetermined length (designated Bl) and diameter (Bd), with the length Bl defined as the length of the bristle extending above the brush base  100 . Both Bl and Bd may be varied as desired to achieve a predetermined stiffness of the bristle tufts  200 . In accordance with the present invention, Bl is no greater than ⅔ of the base radius R. Short bristles relative to the base radius are desirable because they flex less than longer bristles, and tend to wear less quickly. In a preferred embodiment, Bl is approximately one half inch (½″), with Bd having a value between 0.01 and 0.025 inches. The bristles  210  may be made of any suitable pliable material, such as plastic, metal, or natural fibers, and in a preferred embodiment are made of nylon. The bristles  210  may be attached to the brush base  100  by any suitable method, such as thermoplastic welding, mechanical fasteners, or adhesives, and in a preferred embodiment are attached with mechanical fasteners. 
         [0034]    The total brush diameter (designated D), shown in  FIGS. 1 and 3 , as measured bristle tip to bristle tip, is two times the sum of the base radius R and the bristle length, or D=2(R+Bl). The values of D and W are limited by the particular mounting location of the brush, and may vary between different reel mower cutting units. 
         [0035]    As shown in  FIGS. 2 and 4 , each bristle tuft  200  has a predetermined width, (designated Tw). Tufts having a greater width can generally accommodate more bristles  210  for a given value of Bd, and conversely, for a given value of Tw, there will be correspondingly fewer bristles  210  in the tuft as Bd increases. In one embodiment, the bristle tufts  200  are generally cylindrical, and have a diameter corresponding to a Tw of approximately 3/16 of an inch. 
         [0036]    As shown in  FIGS. 2 and 4 , the centers of the bristle tufts within each row are spaced equally apart in a symmetrical fashion along the width of the brush base by a predetermined tuft spacing distance (Ts) no less than one and one half times (1 ½.times.) the tuft width Tw. In the embodiment illustrated in  FIGS. 1 and 2 , Ts is one half inch (½″), and in the embodiment illustrated in  FIGS. 3 and 4 , Ts is one inch (1″). 
         [0037]    According to the present invention, and as shown in  FIGS. 2 and 4 , the bristle tufts  200  in each row are offset relative to those in adjacent rows by a tuft offset value (To) that is the ratio of the distance that the bristle tufts  200  in each row are spaced apart divided by an offset factor that is a divisor of the number of parallel rows. In the embodiment illustrated in  FIGS. 1 and 2 , To is equal to one quarter inch (¼″), and in the embodiment illustrated in  FIGS. 3 and 4 , To is equal to one third inch (⅓″). In accordance with the present invention, the value of To is selected to be no greater than two times the tuft width (2*Tw), and the values of Ts and To are selected to ensure a uniform absolute brush frequency Fa across the contact patch of the brush, taking into account the broadening of the width of the bristle tufts when in contact with a surface. 
         [0038]    As shown in  FIG. 5 , the turf conditioning method and apparatus may comprise a brush sleeve engaging a rotatable drive spindle  400 . In this embodiment, the brush base  100  may be formed as a hollow tube having a bore  120  configured for receiving a drive spindle  400 , and notches  110  at both ends of the brush base  100  configured for engaging roller pins  500  inserted through the drive spindle  400 . The roller pins  500  serve to position the brush base  100  on the drive spindle  400 , and in cooperation with the notches  110  in the brush base  100 , transfer the rotational force from the drive spindle  400  to the brush base  100  and its attached bristle tufts  200 . The rotational force may be applied to the drive spindle  400  through splines  410 , or other suitable means. 
         [0039]    As shown in  FIGS. 7-9 , the design of a modem reel mower  700  cutting unit  800  utilizes a powered reel of several helical blades  830  which rotate in close contact with a fixed bedknife  820  to clip the grass leaves to a uniform height in a scissor like fashion. This cutting unit  800  is generally housed in an assembly, which is generally shown in  FIGS. 8-9 , known as a groomer drive accessory  810  having a groomer drive gear and mounting bracket  811 . The number of blades in a cutting reel  830  varies, with more blades providing a greater “clip frequency” over a given distance of the reel mower  700  cutting unit&#39;s  800  forward travel. The cutting reel  830  and bedknife  820  are generally mounted between two ground-contacting rollers  850  and  860  in a frame that permits the height of cut to be adjusted precisely. In walk-behind reel mowers  700 , the rear roller  850 , also called the traction roller, is powered, and the front roller  860  is generally used to adjust the cutting height. In current walk-behind designs, the cutting reel  830  is either mechanically linked to the engine and drivetrain powering the rear traction roller  850 , or is powered by an electric motor which permits the clip frequency of the cutting reel  830  to be set independent of the engine&#39;s throttle setting and speed of ground travel, an arrangement termed a “hybrid” drive. In ride-on reel mowers  700 , one or more powered helical reel cutting units  800  is pushed or pulled across the grass surface by a tractor, with each cutting unit  800  mounted on its own ground-contacting rollers  850  and/or  860  in a manner that permits the cutting units  800  to individually adjust to the contours of the ground. Hybrid drive systems are also available for the cutting units  800  of ride-on reel mowers  700 . Depending upon the condition of the turf, it may be desired to adjust the height of the brush to apply a greater or lesser brushing intensity or “aggressiveness” of turf conditioning prior to cutting, and as described herein, the present method and system may be embodied in turf conditioning brushes having different degrees of bristle stiffness suitable for various turf conditions and types of grass, the bristle stiffness being determined primarily by the bristle diameter and the material or materials from which the bristles are made. A turf conditioning brush constructed according to the present invention has a generally cylindrical base  100  that is configured to rotate by one of several means, including, but not limited to, being configured as a sleeve rotatably mounted on an axle, a sleeve engaging a rotatable spindle  400 , or the base may be constructed integrally to a rotatable spindle  400 . In a preferred embodiment, the turf conditioning brush is mounted on a drive spindle  400  and the motive force for the rotation of the turf conditioning brush may be supplied by any of several means, including, but not limited to, indirect means such as a geartrain, a drive belt engaging a pulley, a drive chain engaging a sprocket or the sleeve or spindle  400  may be directly driven. In one embodiment, the brush base  100  is configured as a sleeve engaging a rotatable spindle  400 . The direction of rotation of the brush base  100  may be the same as that of the cutting reel  830  or opposite to that of the cutting reel  830 , and in a preferred embodiment the rotation of the brush base  100  is opposite to that of the cutting reel  830 , such that the grass-contacting face of the brush is rotating towards the oncoming grass leaves and away from the cutting reel  830  when the reel mower  700  cutting unit  800  is in forward motion. 
         [0040]    In this embodiment of the invention, shown in a detailed end-on perspective in  FIG. 6 , the bore  120  extends through the entire width of the brush base  100 , and the notches  110  in the end of the brush base are similarly configured at both ends of the brush base  100 . A predetermined number of linear rows N of bristle tufts  200  are arranged radially around the brush base  100 . In a preferred embodiment, the number of rows N of bristle tufts is equal to 12. 
         [0041]    Although the invention has been shown and described with reference to certain specific presently preferred embodiments, the given embodiments should not be construed as limitations on the scope of the invention, but as illustrative examples, and those skilled in the art to which this invention pertains will undoubtedly find alternative embodiments obvious after reading this disclosure. With this in mind, the following claims are intended to define the scope of protection to be afforded the inventor, and these claims shall be deemed to include equivalent constructions insofar as they do not depart from the spirit and scope of the present invention.