Abstract:
An non-contact type reel mower includes a reel having a high rotational inertia, and a cutting gap adjustment system. The reel includes an axle, a plurality of blades helically disposed about the axis at a radial distance from the axis, and a blade support member coupling the blades to the axle, in a manner that locates a majority of the mass of the reel at a location as far from the axle as possible, while still fitting within the size constraints of a standard size mower package. The cutting gap adjustment system includes carrier plates having a forward end pivotally coupled at a forward end of the mower, and a mid portion that supports or carries the reel and a rearward end that is coupled to the mower chassis by an adjustment device. The plates operate as levers pivoting about the pivot points to raise and lower the reel relative to a fixed bedknife to adjust the cutting gap when the adjustment device is actuated at the rearward end of the plates. The adjustment device extends upwardly from the chassis to permit actuation by a user from the top of the mower. The bedknife also serves as a structural member for the chassis of the mower.

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS 
       [0001]    This application claims priority from U.S. Provisional Application 61/210,552, filed Mar. 20, 2009, incorporated herein by reference in its entirety. 
     
    
     FIELD 
       [0002]    The present invention relates to a lawnmower. The present invention relates more particularly to a lawnmower of the reel type (“reel mower”). The present invention relates more particularly to a reel mower having a non-contact cutting blade system. The present invention relates still more particularly to a reel mower having a cutting blade reel with high rotational inertial properties, and an adjustment system for setting a gap or clearance between the cutting blades of the reel and a fixed cutting edge of the mower. 
       BACKGROUND 
       [0003]    This section is intended to provide a background or context to the invention recited in the claims. The description herein may include concepts that could be pursued, but are not necessarily ones that have been previously conceived or pursued. Therefore, unless otherwise indicated herein, what is described in this section is not prior art to the description and claims in this application and is not admitted to be prior art by inclusion in this section. 
         [0004]    One type of reel mower is typically referred to as a “contact” type reel mower, which operates with contact between the reel blades and the fixed cutting edge of the mower (often referred to as a “bedknife”) to sever grass by a contact shearing or scraping operation of the blades. Another type of reel mower is typically referred to as a “non-contact” type reel mower, which tend to be quieter and operates with a small gap between the reel cutting blades and the bedknife to avoid contact and to sever the grass by using a sharper edge against the resistance of the grass. One distinction between the non-contact type reel mowers and the contact type reel mowers is the hardness of the cutting blades. In a non-contact mower, the reel and bedknife blades are often heat-treated to a substantially higher hardness to provide a sharper edge than in a contact type mower. For example, a contact mower may have cutting blades hardened to approximately 20 Rockwell C, while the cutting blades of a non-contact type mower may be above 40 Rockwell C. Optimizing the cutting performance of a non-contact type mower involves carefully setting and maintaining the small gap between the reel cutting blades and the bedknife. A certain degree of precision is typically required in setting the gap; if the gap is too large, than the cutting performance is compromised, and if the gap is too small, the reel cutting blades and the bedknife with their high level of hardness may damage (e.g. chip, abrade, etc.) one another. Conventional devices for setting the cutting gap in non-contact type reel mowers tend to be complicated, inaccurate, and difficult to use, often resulting in improper setting of the gap and poor performance of the mower (e.g. mowers that either do not cut well, are difficult to push, or both). Some conventional mowers have attempted to simplify the adjustment process, but still typically require the user to access the bottom of the mower and/or use mechanic&#39;s tools, both of which tend to discourage regular and necessary adjustment. 
         [0005]    Also, the rotational inertia of the cutting blade reel can effect the performance of a non-contact reel mower. For example, a cutting blade reel with low rotational inertia tends to stall or jam when encountering items that are more difficult to cut than grass, such as weeds, crabgrass, sticks, mulch and the like. However, typical cutting blade reels that attempted to increase rotational inertia by making the cutting blade wider also tend to increase aerodynamic drag and wind resistance, resulting in a level of performance that is less than desired. 
         [0006]    Accordingly, it would be desirable to provide an improved non-contact type reel mower, having a cutting blade reel with high rotational inertia packaged in a standard size mower, and a cutting gap adjustment system that is top-mounted for accessibility and moves the position of the reel relative to a stationary bedknife for setting the gap of the mower with the bedknife forming a structural portion of the mower. 
       SUMMARY 
       [0007]    According to one embodiment, an reel mower includes a reel having a high rotational inertia. The reel includes an axle, a plurality of blades helically disposed about the axis at a radial distance from the axis, and a blade support member coupling the blades to the axle, in a manner that locates a majority of the mass of the reel at a location as far from the axle as possible, while still fitting within the size constraints of a standard size mower package. The reel has a diameter of approximately 175 mm and a length of approximately 460 mm, and the blades have a thickness of 4.5 mm and a width of approximately 30 mm wide. 
         [0008]    According to another embodiment, a cutting gap adjustment system for a reel mower includes generally parallel carrier plates having a forward end pivotally coupled at a forward end of the mower, and a mid portion that supports or carries the reel and a rearward end that is operably coupled to a chassis of the mower by an adjustment device. The plates operate as levers pivoting about the pivot points to raise and lower the reel relative to a fixed bedknife to adjust a gap between the reel and the bedknife when the adjustment device is actuated to raise or lower the rearward end of the plates. Location of the reel proximate the mid portion of the plates permits a relatively small amount of gap adjustment that corresponds to a relatively large amount of movement of the adjustment device. The adjustment device extends upwardly from the chassis to permit actuation by a user from the top of the mower. Adjusting the gap by moving the reel relative to a stationary bedknife, permits the bedknife to also serve as a structural member for the chassis of the mower. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  is a graphic image of a perspective view of a non-contact type reel mower with a high rotational inertia reel and a cutting gap adjustment system, according to an exemplary embodiment. 
           [0010]      FIG. 2  is a graphic image of a side elevation view of a non-contact type reel mower with a high rotational inertia reel and a cutting gap adjustment system, according to an exemplary embodiment. 
           [0011]      FIG. 3  is a graphic image of a perspective view of a cutting blade reel with a high rotational inertia for a reel mower, according to an exemplary embodiment. 
           [0012]      FIG. 4  is a graphic image of a side elevation view of a cutting blade reel with a high rotational inertia for a reel mower, according to an exemplary embodiment. 
           [0013]      FIG. 5  is a graphic image of a perspective view of a cutting blade reel with a high rotational inertia for a reel mower, according to another exemplary embodiment. 
           [0014]      FIG. 6  is a schematic image of a side elevation view of a cutting blade reel and a bedknife interface for a non-contact type reel mower, according to an exemplary embodiment. 
           [0015]      FIG. 7  is a schematic image of a perspective view of a non-contact type reel mower with a high rotational inertia reel and a cutting gap adjustment system, according to an exemplary embodiment. 
           [0016]      FIG. 8  is a schematic diagram of a side elevation view of a pivot and lever arrangement for a cutting gap adjustment system of a non-contact type reel mower, according to an exemplary embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0017]    Referring to the FIGURES, a reel mower  10  is disclosed having a cutting blade reel  30  with a high polar moment of inertia, and a cutting gap adjustment system  50  for setting a gap or clearance between the cutting blades of the reel and a fixed cutting edge of the reel mower, according to an exemplary embodiment. 
         [0018]    Although specific examples are shown and described throughout this disclosure, the embodiments illustrated in the FIGURES are shown by way of example, and any of a wide variety of other configurations, shapes, sizes and locations of components, and combinations thereof, will be readily apparent to a person of ordinary skill in the art after reviewing this disclosure. Further, although the reel mower has been shown and described by way of example for a non-contact type mower, the elements and features of the invention are capable of use in other lawn mowing applications. All such variations of the high inertial reel and the cutting gap adjustment system are intended to be within the scope of the invention. 
         [0019]    Referring to  FIGS. 1-8 , a non-contact type reel mower  10  with a high rotational inertia cutting blade reel  30  and a cutting gap adjustment system  50  is shown according to an exemplary embodiment. The reel mower  10  includes a main chassis  12  with rear drive wheels  14  located rearward on the chassis  12  and smaller height-adjustment front wheels  16  are located forward on the chassis  12  (often referred to as a front-mount or front-throw reel mower). The front wheels  16  are interconnected by a cross member  18  so that the cutting elevation of the reel mower may be raised or lowered by adjusting a single handle  20  to effect an elevation change of both front wheels  16 . The cutting blade reel  30  is shown located forward of (i.e. in front of) the large rear drive wheels  14  and is driven by a chain and sprocket system from the rear wheels (not shown for clarity). A fixed cutting blade (referred to herein as a bedknife  22 ) is mounted to the chassis  12  and positioned to interface with the rotating cutting blades  32  of the reel  30  through a small gap  24  to provide a non-contact shearing relationship. 
         [0020]    Referring more particularly to  FIGS. 3-6 , a cutting blade reel  30  having high rotational inertia is disclosed to increase the momentum of the reel and provide stored energy storage that can assist in cutting through difficult items (e.g. weeds, crabgrass, sticks, mulch, etc.), according to an exemplary embodiment. The cutting blade reel  30  as shown is intended to have a large rotational inertia, thus providing more momentum than conventional reels, and because of the application in a non-contact type mower, this additional momentum is available to assist in cutting during momentary high loads, such as hitting weeds, a thick clump of grass, small branches and the like. Such a high rotational inertia cutting blade reel is intended to provide an advantageous improvement over conventional cutting blade reels that tend to include a flywheel or other separate component to increase the momentum of the cutting blades. 
         [0021]    Reel  30 , according to the illustrated embodiment, concentrates mass away from the axis of rotation “A” to increase the rotational moment of inertia of the cutting blade reel  30 . According to the illustrated embodiment of the mower  10 , the rotational inertia of the reel  30  depends on at least several primary factors, including the length and diameter of the reel  30  and the mass of the blades  32 . According to one embodiment, the reel  30  has a diameter of approximately 175 mm, and the blades  32  have a thickness “T” of 4.5 mm and a width “W” of approximately 30 mm wide, which are intended to place much of the reel&#39;s mass outward from the central axle  34  (and the corresponding axis of rotation A). For example, in standard size reel mower applications having a reel length (i.e. cutting width) of approximately 460 mm, the resulting moment of inertia about the axis of rotation A of the reel  30  is at least 5,000,000 g*mm2, more preferably approximately 10,000,000 g*mm2, more preferably still approximately 15,983,633 g*mm2. The Applicants believe that this result is approximately five times greater than the typical rotational inertia of most conventional cutting blade reels. 
         [0022]    Since a contact type reel mower with a high reel inertia tends to lose its momentum due to friction between the reel cutting blades and the bedknife, the Applicants have developed a reel that is more “dense” in rotational inertia, yet is still contained within the size constraints of a standard size mower, and that uses a non-contact cutting system to allow the reel to spin more freely. 
         [0023]    According to the exemplary embodiment, the blade  32  has an increased thickness “T” (i.e. the circumferential dimension) and a reduced width “W” (i.e. the radial dimension), in order to concentrate the mass of the cutting blades  32  as far from the axis of rotation A as possible and to reduce aerodynamic drag and wind resistance of the cutting blades  32  as they rotate about the axis of rotation A of the reel  30 . According to one embodiment, the cutting blades  32  of the reel  30  are made from hardened steel to provide the desired sharpness of the cutting edge of the blades  32  to avoid ‘crushing’ the cut grass against the bedknife  22 . For example, the blades are shown to have a cutting edge formed by the intersection of flat width of the blade and the circumferential edge made by a cylindrical grinding operation, while a relief is provided to reduce the thickness of the blade at the cutting surface to reduce ‘crushing’ of the grass clippings and thereby reducing the force necessary to spin the reel. The cutting edge may be ground in, or rolled into, the sheet metal shape of the blade  32 . However, according to alternative embodiments, a heavier material (e.g. lead, etc.) may be used and provided with a steel or ceramic cutting edge. Also, weights of a higher-density material (e.g. lead, etc.) may be added to steel cutting blades to increase mass without increasing the width W of the blade. 
         [0024]    The reel also includes blade support members (e.g. disks, etc., referred to further herein as “spiders”  36 ) extending from the axle  34  to support the blades  32 . In order to further reduce overall mass, the axle  34  and blade support members  36  further help concentrate the reel&#39;s mass in the cutting blades may include apertures (e.g. holes, etc.—not shown) in the spiders  36 , and the spiders  36  may be formed from a low-density material (e.g. aluminum, etc.). 
         [0025]    According to an alternative embodiment, the mass of the reel may be concentrated on some part other than the cutting blades of the reel. For example, the reel may include thin, lightweight blades and weights mounted separately near the periphery of the reel. Also, the blades may be mounted to a massive cylinder, itself mounted to the shaft, and providing a large area over which to distribute the mass distant from the axis of rotation. Further, ring weights (e.g. toroidal weights, etc,)  38  may be mounted just inside of the edge of the cutting blade, and oriented approximately parallel to the spiders (see  FIG. 5 ). 
         [0026]    Referring now more particularly to  FIGS. 1 ,  2 , and  6 - 8 , a cutting gap adjustment system  50  for setting and controlling the gap  24  between the cutting blades  32  of the high rotational inertia reel  30  and the bedknife  22  for a non-contact reel mower  10  are disclosed, according to an exemplary embodiment. The cutting gap  24  is shown more particularly in  FIGS. 2 and 6  as the amount of space or clearance in a generally vertical direction between the cutting blades  32  of the reel  30  and the bedknife  22 . However, the gap may be any desired amount of space or clearance having any suitable orientation depending on the location and relationship of the cutting blades and the bedknife with respect to one another. Although the cutting gap adjustment system is shown and described for a non-contact type reel mower, the system is also adaptable for use with a contact type reel mower. 
         [0027]    The cutting gap adjustment system  50  controls the size or dimension of the gap  24  (if present) or the amount of contact pressure between the cutting edge of the reel blades and the stationary bedknife (i.e. the fixed, opposing blade mounted on the bottom of the mower that engages the reel cutting blades in a shearing relationship). In both cases, careful control of the relative position of the reel cutting blades and bedknife is desirable for optimal performance of the mower. For contact mowers, a contact pressure that is too high results in both excessive power being needed to drive the reel and accelerated wear of the cutting edges. In contrast, a contact pressure that is too light results in failure of the blades to cut properly. For non-contact reel mowers, a gap that is too large may result in a poor cut (or no cut at all), while contact between the cutting blades and bedknife tends to damage the cutting blades and bedknife. In both cases, the difference between optimal performance and poor performance is generally understood to be a matter of a several thousandths of an inch at the interface between the blades and the bedknife. 
         [0028]    According to the illustrated embodiment, the reel  30  is movable relative to the main chassis  12  of the reel mower  10  to provide the desired adjustment of the gap  24  (or contact pressure in the case of a contact type mower). The reel  30  is supported by a pair of opposed reel carrier plates  52  disposed on opposite sides of the mower  10 . Each reel carrier plate  52  is configured to pivot about a pivot point  54  disposed at a front end of the mower  10 . The reel carrier plates  52  each include a forward end  58  and a rearward end  60 , and a midportion  62 . The forward end  58  of the plates  52  are pivotally coupled to the mower at pivot point  54 . The pivot point  54  is shown by way of example to pivot about the cross member  18  for the front wheels  16 , or as located coincident with the cross member  18 , but may be arranged to pivot about any suitable point proximate the front end of the mower  10 . As such, the reel carrier plates  52  are configured to operate as ‘levers’ to raise and lower the reel  30  by raising and lowering the rearward end  60  of the plates by an adjustment device  70  conveniently disposed on a top side of the mower  10 . 
         [0029]    The rearward end  60  of the reel carrier plates  52  are coupled to the adjustment device  70 , which engages the main chassis  12  of the mower  10  and extends upwardly from the mower  10 . The adjustment device  70  is operable to raise or lower the rearward end  60  of the reel carrier plates  52  to raise or lower the reel  30  as the forward end  58  of the reel carrier plates  52  pivot about the pivot points  54 . According to one embodiment, the adjustment devices  70  each comprise a pair of substantially vertical threaded members  72  (e.g. screws, etc.) that may be adjusted (i.e. rotated about their axis) to raise and lower the reel carrier plates  52  relative to the chassis  12 . The adjustment devices  70  are further shown to include springs  74  (shown for example as coil springs) that bias the rearward ends  60  of the reel carrier plates  52  upward against the threaded members  72  (e.g. against a shoulder, head or other suitable structure on the threaded member) to bias the reel carrier plates upward to an adjustment position established by the threaded members  72 . 
         [0030]    Referring further to  FIGS. 2 and 6 , as the reel carrier plates  52  are raised or lowered, the reel  30  is also raised or lowered relative to the bedknife  22  to adjust the gap  24  between the cutting blades  32  of the reel  30  and the bedknife  22 . Each reel carrier plate  52  may be adjusted independently of the other to more precisely set and control the gap  24  (or contact pressure for a contact type mower). Placement of the adjustment device  70  proximate the top of the mower  10 , is intended to enhance the adjustability and make operation of the cutting gap adjustment system  50  faster, simpler, and more reliable. Further, the top-mounted location of the adjustment device  70  provides quick and convenient access, encouraging a user to check the adjustment of the gap and speeding the adjustment process. The top mounted location is also intended to provide room for the use of ergonomic knobs  76  for use in turning the threaded members  74 , which do not typically fit beneath a mower, thus providing tool-free adjustment capability for the cutting gap adjustment system  50 . 
         [0031]    According to an alternative embodiment, the reel carrier plates may be interconnected to permit adjustment of both reel carrier plates with a single (e.g. common, etc.) adjustment device. For example, a cross-member (or other substantially rigid framework) may be provided connecting the reel carrier plates to one another and a single adjustment device provided that operably engages the cross-member (or one of the reel carrier plates or framework) and the mower chassis, to adjust both reel carrier plates relative to the chassis and set the gap using a single adjustment operation, and also serves to maintain alignment of bearings  78  provided on opposite ends of the axle  34  for the reel  30 . According to one embodiment, the bearings  78  are on (or within) the reel carrier plates  52  so that raising or lowering the rearward end  60  of the reel carrier plates  52  results in a desired change in elevation of the reel  30 . 
         [0032]    As shown further in  FIGS. 2 and 8 , the length of the reel carrier plates  52  are relatively long between the reel  30  and the adjustment device(s)  70  and relatively short between the reel  30  and the front pivot point  54 , so that a ‘coarse’ adjustment of the threaded member  72  (corresponding to a relatively large elevation change at the rearward end  60  of the reel carrier plates  52 ) would result in a relatively small elevation change of the midportion  62  of the reel carrier plates  52  and the reel  30 , and is intended to provide fine-tuning capability for the adjustment system. The motion-reducing nature of the reel carrier plates  52  that operate in the form of levers about a front pivot point  54  means that for a given pitch of the threaded member  72 , a larger input motion is necessary to effect a given output at the reel  30 , and is intended to reduce the sensitivity of the cutting gap adjustment system  50  to user “feel” and error. 
         [0033]    According to one embodiment, the reel  30  may be mounted approximately at a midpoint of the reel carriers plates  52 , in order to provide the smallest overall length for the mower  10 , while still providing an approximate  2 -to- I reduction in motion from the adjustment device(s)  70  to the reel  30 . The adjustment devices  70  also include a locking device to fix the threaded members in place after adjustment of the gap  24  has been set, and is intended to minimize the drift, misalignment or other unintended change of the gap  24  (or contact pressure for contact type mowers). 
         [0034]    The adjustment device  70  may also include a device intended to automatically set the appropriate gap  24  for optimal cutting of a non-contact type mower. For example, a cam, detent, or other generally fixed-offset device (not shown) may be provided to cause a controlled amount of motion of the reel  30  after it has been adjusted into contact with the bedknife  22 , after which the adjustment device  70  may be locked in place. For example, a lever and cam may be pivotally coupled to the chassis and operable to engage the rearward end of the carrier plates (or framework), so that after having set the reel cutting blades into contact with the bedknife, an operator may move the lever to engage the cam with the plate(s) to move the plates a pre-defined amount corresponding to a factory-preset gap position. According to one embodiment, the gap  24  between the cutting blades  32  and the bedknife  22  is less than approximately 0.5 mm, and more particularly less than approximately 0.1 mm, and the reel cutting blades and bedknife are heat-treated to a hardness above approximately 40 Rockwell C, and more particularly above approximately 45 Rockwell C. However, other suitable gap dimensions and cutting blade/bedknife hardness levels may be used as desired to suit a particular application. 
         [0035]    According to an alternative embodiment, the adjustment device may omit the use of threaded members and include other adjustment features. For example, fine intermeshing toothed racks may be provided on each of the chassis and the rearward end of the reel carrier plate(s) that may be ‘snapped’ from one discrete position to another, corresponding to predefined gaps dimensions. Also, the rearward end of the reel carrier plates may be clamped into position with suitable clamps (e.g. bolts, over-center levers, etc.), that may be manually released to change the elevation or position of the reel and then tightened or engaged upon establishing the desired gap setting. Further, the reel carriers may be made wholly or partly flexible (using a material such as fiberglass, carbon fiber or spring steel portions, etc.), such that when the flexible members are flexed (e.g. bowed, etc.) by the adjustment device, the amount of ‘arch’ of the members would also change and thereby cause an increased or decreased gap between cutting blades and the bedknife. In addition, the reel carrier plate(s) may be provided at their rearward end with a spring-biased rotatable cam (e.g. coupled to the plates by a common shaft or the like) that engages the chassis so that rotation of the cam raises or lowers the reel a pre-determined amount. A suitable locking device (e.g. clamp, latch, travel-stop, etc.) may also be provided to maintain the reel in a fixed position once the desired gap had been set. 
         [0036]    Generally, the bedknife of a reel mower is a relatively rigid and stout member, since its straightness tends to affect the ability of the mower to cut uniformly, particularly for non-contact type mowers. Many conventional mowers typically adjust the gap between the reel cutting blades and the bedknife by moving the bedknife, thus separating the bedknife from the mower chassis, and eliminating the ability of the bedknife to serve as a reinforcing element or other structural element of the mower chassis. In contrast, the gap adjustment feature of the present invention is intended to enhance the ease and accuracy of gap adjustment, while also permitting the bedknife to serve the additional purpose of functioning as a chassis brace to provide a more rigid structure without the added mass associated with additional structure or braces that are common in conventional reel mowers. 
         [0037]    According to any exemplary embodiment, the cutting gap adjustment system  50  is mechanically simple, and allows for user adjustment of the gap  24  from the top of the mower  10  through a lever-type motion-reducing pivoted linkage to move the reel  30 , without releasing the cutting blade reel or the bedknife) to free-float, which tends to make adjustment with a desired precision difficult without complex external fixtures. The system also allows the bedknife to serve as a chassis brace, reducing overall weight, complexity and cost for the mower. 
         [0038]    It is also important to note that the construction and arrangement of the elements of the reel mower as shown schematically in the embodiments is illustrative only. Although only a few embodiments have been described in detail in this disclosure, those skilled in the art who review this disclosure will readily appreciate that many modifications are possible without materially departing from the novel teachings and advantages of the subject matter recited. 
         [0039]    Accordingly, all such modifications are intended to be included within the scope of the present invention. Other substitutions, modifications, changes and omissions may be made in the design, operating conditions and arrangement of the preferred and other exemplary embodiments without departing from the spirit of the present invention. 
         [0040]    The order or sequence of any process or method steps may be varied or re-sequenced according to alternative embodiments. In the claims, any means-plus-function clause is intended to cover the structures described herein as performing the recited function and not only structural equivalents but also equivalent structures. Other substitutions, modifications, changes and omissions may be made in the design, operating configuration and arrangement of the preferred and other exemplary embodiments without departing from the spirit of the present invention as expressed in the appended claims.