Abstract:
A walk-behind greens mower having a mobile structure and a ground engaging traction member rotatably coupled to the mobile structure. The ground engaging traction member imparts traction movement to the mobile structure for movement on the ground at a ground speed. An internal combustion engine is supported on the mobile structure and outputs a driving force to the ground engaging traction member. A bed knife is supported by the mobile structure having a cutting edge that cooperates with a grass cutting reel rotatably supported on the mobile structure. An electric motor supported on the mobile structure rotatably driving the grass cutting reel at a rotational speed that can vary depending upon the detected ground speed.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to greens mowers and, more particularly, relates to a greens mower having an internal combustion engine traction drive and an electric cutting unit drive for improved cutting performance and operation.  
       BACKGROUND OF THE INVENTION  
       [0002]     As is known in the prior art, greens mowers are particularly useful in mowing golf course greens, which are known to require exacting mowing results to assure that the grass is cut consistently throughout the green. Traditionally, these greens mowers are either walk-behind type mowers or riding mowers.  
         [0003]     Greens mowers generally employ a reel type mowing unit as opposed to a rotary type mowing unit. The clip rate of these reel type mowing units are of utmost concern due to the fact that the clip rate often determines the consistency and quality of the cut, which leads to improved turf health. Because of the time required to grow a mature green and the cost associated with therewith, it is extremely important that greens mowers operate properly and not damage the turf.  
         [0004]     The term clip rate is generally understood to mean the ratio between the rotational speed of the reel and the corresponding speed of the traction or drive unit. The clip rate can often be measured by the distance between the locations of individual sequential grass cuts produced by the rotating reel blades successively moving over the grass. The grass between the locations of the cuts will necessarily be left taller than the cut grass at the cut locations. Consequently, the cut rate is vital to producing an optimum condition of the grass on the golf course green.  
         [0005]     Golf course greens maintenance equipment traditionally has utilized internal combustion engines. A number of greens mowers are known in the art. Some are discussed in U.S. Pat. Nos. 3,429,110, and 4,024,996. Riding greens mowers with multiple or gang mowing units are the subject of U.S. Pat. Nos. 3,511,033, 3,668,844, 4,866,918, and 5,042,236. All of the recited patents referenced above are incorporated herein by reference. The mowers discussed in these patents all rely on an internal combustion engine as the primary source of power and a complex drive mechanism of drive belts, gears, and/or chains or a hydrostatic system for supplying power to the ground engaging wheels and additionally to the reel mowing units. However, there are a number of disadvantages associated with the use of a greens mower employing an internal combustion engine to power both the drive mechanism and the mowing unit.  
         [0006]     As will be appreciated by one skilled in the art, traditionally internal combustion powered greens mowers have a first disadvantage of preventing quick and convenient variation of the clip rate, because of the fixed mechanical relationship between the drive mechanism and the mowing unit. In other words, the fixed gear ratio defined by the drive belts, gears, and/or chains does not facilitate quick and convenient modifying of the clip rate without the changing of gear members or the use of variable transmissions. Consequently, the clip rate of a particular greens mower is often unchangeable without considerable time and effort.  
         [0007]     Additionally, recently there has been an increased interest in greens mowers having a floating or articulating mowing unit. These articulating mowing units have the ability to follow any undulations in the green more closely to provide improve cut quality over varying greens topography. However, it should be appreciated that the mechanical drive unit extending between the internal combustion engine and the articulating mowing unit is often complex and cumbersome due to the inherent need to continually provide drive power as the mowing unit articulates relative to the engine.  
         [0008]     Still further, such conventional greens mowers often employ complex disengagement systems that the operator is required to actuate in order to engage and disengage the mowing unit. These systems often require the operator to actuate a lever separate from the handle, which may lead to undesirable cutting performance as the mowing unit is being disengaged.  
         [0009]     Accordingly, there exists a need in the relevant art to provide an internal combustion powered greens mowers that is capable of consistently maintaining a desired clip rate that is both reliable and easily configurable. Additionally, there exists a need in the relevant art to provide an internal combustion powered greens mowers that can operably drive an articulating mowing unit without the need for complex mechanical drive systems. Furthermore, there exists a need in the relevant art to provide a greens mower having a simple and safe disengagement system to permit the quick and convenient turning on and off of the mowing unit. Lastly, there is a need in the relevant art to provide a greens mower that overcomes the disadvantages of the prior art.  
       SUMMARY OF THE INVENTION  
       [0010]     According to the principles of the present invention, a walk-behind greens mower having an advantageous construction is provided. The greens mower includes a mobile structure and a ground engaging traction member rotatably coupled to the mobile structure. The ground engaging traction member imparts traction movement to the mobile structure for movement on the ground at a ground speed. An internal combustion engine is supported on the mobile structure and outputs a driving force to the ground engaging traction member. A bed knife is supported by the mobile structure having a cutting edge that cooperates with a grass cutting reel rotatably supported on the mobile structure. An electric motor supported on the mobile structure rotatably driving the grass cutting reel at a rotational speed that can vary depending upon the detected ground speed.  
         [0011]     Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]     The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:  
         [0013]      FIG. 1  is a perspective view illustrating a greens mower according to the principles of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0014]     The following description of the preferred embodiment is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.  
         [0015]     With reference to the figure,  FIG. 1  illustrates a greens mower  10  incorporating the principles of the present invention. Greens mower  10  is a reel-type mower having a base portion  12  and a floating or articulating mowing unit  14 . Mowing unit  14  is articulately coupled to base portion  12  through a pivoting mechanism  16 .  
         [0016]     Mowing unit  14  includes a rotatable greens mower reel  18  having spiraled blades  20  equally spaced around a reel shaft  22 . Reel shaft  22  is generally elongated and defines a rotation axis  24  extending along the length of reel shaft  22 . A conventional fixed bed knife (not shown) is operably mounted to mowing unit  14 . Blades  20  orbit relative to shaft  22  and move past the fixed bed knife for the usual and well-known function of cutting the grass. Mowing unit  14  further includes a pair of ground engaging rollers  26  rotatably mounted along a forward and rearward portion of mowing unit  14 . The pair of ground engaging rollers  26  serve to support mowing unit  14  for movement on the ground. The pair of ground engaging rollers  26  are preferably adjustable to define a cutting height.  
         [0017]     Mowing unit  14  further includes a variable electric motor  28 . Electric motor  28  is illustrated mounted to a side member  30  of mowing unit  14 . Electric motor  28  is then operably coupled to reel  18  to rotatably drive reel  18  through a transmission system (not shown). The transmission system may include belts, gears, chains, or the like in a conventional fashion to transfer the drive force from electric motor  28  to reel  18 . As should be appreciated, however, the transmission system extending between electric motor  28  and reel  18  is simple in construction, because it is directly mounted to mowing unit  14 . Therefore, any articulation of mowing unit  14  does not affect the relative positional relationship of the drive motor and the reel, as is common in prior art articulating greens mowers. Consequently, the transmission system need only include the necessary pieces to define a range of rotational speeds relative to the capacity of electric motor  28 , such as a simple gear train.  
         [0018]     Although electric motor  28  is illustrated mounted to side member  30  of mowing unit  14 , it should be appreciated that electric motor  28  may be mounted in any one of a plurality of locations. For example, electric motor  28  may be mounted generally above reel  18 , either to one side or centered, or, alternatively, electric motor  28  may be mounted within reel shaft  22  to provide additional protection of electric mower  28  from environmental damage and to provide improved weight balance of mowing unit  14 .  
         [0019]     Base portion  12  generally includes an internal combustion engine  32 , a frame  34 , a lawn roller  36 , a drive system  38 , and a handle assembly  40 . Internal combustion engine  32  is of conventional design and is mounted on frame  34 . Internal combustion engine  32  may include an electric starter for improved convenience. Internal combustion engine  32  further includes a generator  42  outputting electrical power during engine operation. The electrical power from generator  42  is transferred to electrical motor  28  via a flexible line  44  to drive electrical motor  28  and, thus, reel  18 .  
         [0020]     Lawn roller  36  is rotatably mounted to frame  34  through a roller axle  46 . Lawn roller  36  supports base portion  12  on the ground and serves as the traction drive for greens mower  10 . Other ground-supporting traction members could be substituted. Drive system  38  is operably coupled between an output shaft  48  and lawn roller  36 . Drive system  38  generally includes a drive pulley (not shown) mounted to output shaft  48  for rotation therewith and an idler pulley (not shown) mounted to lawn roller  36  for rotation therewith. A drive belt (not shown) extends between the drive pulley and the idler pulley to transfer drive force from internal combustion engine  32  to lawn roller  36 . Thus, there exists a traction drive train from internal combustion engine  32  to the ground-engaging lawn roller  36  capable of driving greens mower  10  in at least a forward direction.  
         [0021]     Handle assembly  40  includes a handle  50  suitably connected with frame  34 . Handle  50  includes a grip portion  52  which the operator can hold in steering greens mower  10 . A movably mounted bail or operator hand control  54  is pivotally connected to handle  50  and is movable toward and away from the grip portion  52 . The operation of hand control  54  may be similar to that disclosed in commonly owned U.S. Pat. No. 6,523,334, which is incorporated herein by reference. In this arrangement, the operator can hold both handle  50  and hand control  54  while guiding greens mower  10 . Upon release of hand control  54 , traction drive system  38  is interrupted in a manner similar to that disclosed in the &#39;334 patent.  
         [0022]     Additionally, the vicinity of handle  50  further includes electrical elements  56  mounted thereon, which are therefore presented to the user for observation or actuation. A mower controller  58  is mounted on handle assembly  40 .  
         [0023]     Mower controller  58  is preferably a central processing unit capable of monitoring and controlling the various functions of greens mower  10 . Although mower controller  58  may be configured in any number of ways conducive to a desired operation, mower controller  58  is most preferably in communication with electric motor  28  via a wire  60 . In this regard, mower controller  58  is capable of controlling a rotational speed of reel  18 . This control capability can be simple to maintain a desired revolutions per minute, irrespective of drive speed of greens mower  10 . However, more desirably, mower controller  58  instead is capable of varying the rotational speed of electric motor  28  and, thus, reel  18  in portion to a detected drive speed of greens mower  10 . The drive speed of greens mower  10  may be detected using a sensor operably coupled to either lawn roller  38  or rollers  26 . This sensor outputs a signal in response to a detected rotational speed of lawn roller  38  or rollers  26 , which is used by mower controller  58  to determine the drive speed of greens mower  10 . Accordingly, an output signal from mower controller  58  to electric motor  28  varies the rotational speed of electric motor  28 , thereby varying the clip rate of reel  18 .  
         [0024]     Furthermore, mower controller  58  preferably includes an operator actuatable switch  62  for conveniently turning on or off electric motor  28  to selectively drive reel  18 . Switch  62  may be conveniently located on handle  50  such that the operator need not remove her hands from handle  50  during operation. Such a switch permits reel  18  to be turned on or off for improved safety and longevity.  
         [0025]     Still further, an optional battery  64  may be coupled to frame  34 . Battery  64  may be used to aid in the starting of internal combustion engine  32 , power electrical elements  56 , and/or power electric motor  28 , either solely or in combination with generator  42 .  
         [0026]     As should be appreciated from the discussion above, the present invention provides a number of advantages over the prior art. Particularly, the present invention provides an internal combustion powered greens mowers that is capable of consistently maintaining a desired clip rate that is both reliable and easily configurable. Additionally, the present invention provides an internal combustion powered greens mowers that can operably drive an articulating mowing unit without the need for complex mechanical drive systems. Still further, the present invention provides a greens mower having a simple and safe disengagement system to permit the quick and convenient turning on and off of the mowing unit.  
         [0027]     The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.