Abstract:
A multi-string lawnmower that has a multi-tiered housing to which is mounted to at least one electric motor coupled to a battery. There are a plurality of mandrel shafts arranged in rows mounted to bearings on the underside of the housing. The mandrel shafts are associated with roller guides and engage a serpentine belt, that is powered by the at least one electric motor. The serpentine belt imparts rotational motion to the mandrel shafts such that adjacent shafts rotate in opposite directions. The cutting elements or strings are attached to the mandrel shafts and are held in place by centrifugal force.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to lawn mowing devices, and with more particularity the invention relates to lawn mowing devices having multiple string cutter elements. 
     Traditional gas powered lawnmowers include both the push and riding type of mowers. The riding mowers typically provide a much larger cutting path but can cost several thousand dollars. Large riding mowers require constant maintenance including tune-ups, blade sharpening, filters that need replacing, and other such maintenance tasks. Gas powered lawnmowers also produce environmentally unfriendly emissions due to the combustion of gasoline needed to power the device. The gasoline engines used typically result in the production of a sizeable amount of noise, which in and of itself acts as a form of pollution. 
     Large gas powered lawnmowers utilizing metal blades as the cutting element also may pose a danger, as they may propel small objects such as rocks and other forms of debris that may be present in the lawn cutting path. 
     It is therefore an object of the present invention to provide an electric powered lawn mowing device that is environmentally friendly and does not produce combustible emissions or noise associated with the use of a gas powered engine. It is also an object of the present invention to replace the large metal blades associated with most gas powered lawnmowers with a plurality of cutting strings which would not propel objects, as is common with a metal blade design. It is also an object of the present invention to provide a lightweight, hand propelled mower that will cut as wide a swatch as a large, gas-powered lawn mower. It is also an object of the present invention to produce a cost-effective lawn-mowing device that is easy to use and requires a minimal amount of maintenance. 
     SUMMARY OF THE INVENTION 
     There is provided a lawn mowing device which cures those deficiencies outlined above by providing a multi-string lawnmower that includes a multi-tiered housing having upper and lower tiers with a middle tier defined by the spacing of the upper and lower tiers. The housing further includes front and rear wheels to allow for the movement of the lawn-mowing device. A handle is attached to the housing to provide the user a means of propelling the lawnmower, as well as to allow for directing the path of the lawnmower. A battery is disposed on the upper tier of the housing and is connected to at least one electric motor that is also disposed on the upper tier. The motor is connected to a shaft, which in turn is coupled to a pulley. A plurality of mandrel shafts are connected to bearing assemblies that are disposed on a lower surface of the upper tier. A serpentine belt engages the pulley and also engages the plurality of mandrel shafts to impart rotational motion to the mandrel shafts. A plurality of roller guides are positioned in cooperative relationship with the mandrel shafts to allow for engagement of the mandrel shafts with the serpentine belt. The serpentine belt engages the mandrel shafts in such a manner that the rotation of adjacent shafts are in opposite directions. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The various advantages of the present invention will become apparent to one skilled in the art by reading the following specification and claims and by referencing the following drawings in which: 
       1 FIG. 1 is a top view of the multi-string lawnmower of the present invention; 
     FIG. 2 is a bottom view of the multi-string lawnmower of the present invention; 
     FIG. 3 is a top view of the multi-string lawnmower of the present invention depicting the cutting radiuses of the various cutting elements; 
     FIG. 4 is a front view of the multi-string lawnmower of the present invention; 
     FIG. 5 is an exploded view of the interengagement of the mandrel shaft and cutting string of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIGS. 1 and 4, a multiple string lawnmower  5  is depicted. The multiple string lawnmower  5  includes a multi-tiered housing  10  including upper  15  and lower  20  tiers and also a middle  25  tier defined by a spacing of the upper  15  and lower  20  tiers. The multi-tiered housing  10  is preferably made of a lightweight and rigid glass reinforced plastic. 
     Front  30  and rear  35  wheels are disposed on the multi-tiered housing  10  for allowing movement of the multi-string lawnmower  5 . As can be seen in FIG. 1, the front wheels are placed on opposite sides of the housing  10  and are aligned to provide a straight travel path for the mower  5 . The rear  35  wheels are disposed on a rear of the housing  10  and are spaced near the center line of the rear of the housing  10  to provide for ease in pivoting the lawnmower  5  while in operation. A handle  40  is attached to the multi-tiered housing  10  to provide a means of propelling the multi-string lawnmower  5  as well as to allow for direction controlled by an operator of the lawnmower. 
     A battery  45  is disposed on the upper  15  tier of the multi-tiered housing  10  and is connected to at least one electric motor  50 , although two are depicted in the preferred embodiment shown in FIGS. 1 through 4. The battery  95  may be an automatic or a manual battery commonly found in the United States. The electric motor  50  is coupled to a shaft  55 . The shaft  55  is in turn connected to a pulley  60  which engages a serpentine belt  90 , as will be described in more detail below. 
     With reference to FIGS. 2 and 4, there are shown a plurality of mandrel shafts  65  having first  70  and second  75  ends. The mandrel shafts extend through the lower  20  and middle  25  tiers and connect to bearing assemblies  80  that are disposed on a lower surface  85  of the upper tier  15 . A plurality of roller guides  95  are positioned in a cooperative relationship with the mandrel shafts  65  to facilitate the engagement of the mandrel shafts  65  with the serpentine belt  90 . As can be seen in FIG. 2, the serpentine belt  90  is coupled to the pulleys  60  which provide a rotational drive to the serpentine belt  90 . The serpentine belt  90  engages the plurality of mandrel shafts  65  and the plurality of roller guides  95  such that the direction of rotation of adjacent mandrel shafts are in opposite directions. There is also included a constant tension pulley  86  for preventing the serpentine belt  90  from becoming slack. The use of a serpentine belt  90  allows for the engagement of any number of mandrel shafts  65 , which in turn allows for various dimensions of lawn-mowing devices  5 . The serpentine belt  90  should be made of a long wearing material, such as those commonly used in the automobile industry. 
     With reference to FIG. 5, the mandrel shafts  65  have holes  67  formed radially through them radially on their second ends  75 . There is also a counter-bore  82  formed on the hole  67  to allow for the engagement of the cutting elements  100 . The cutting elements  100  are high density, glass reinforced, plastic strings  105  that have stops  110  formed on one end. The strings  105  are inserted through the hole  67  and the stops  110  are received within the counter-bore  82  to provide a cutting element. The centrifugal force generated by the rotation of the mandrel shafts  65  maintain the strings  105  within the mandrel shafts  65 . The preferred rotation of the mandrel shafts is from 5,000 to 8,000 rpm and is sufficient to maintain the strings  105  in contact with the mandrel shafts  65 . 
     With reference to FIGS. 2 and 3, the mandrel shafts  65  are positioned in first  120  and second  125  rows in relation to the multi-tiered housing  10 . The number of mandrel shafts  65  in the first row  120  is less than the number of mandrel shafts  65  in the second row  125 . This relationship is maintained, as it is preferred that the length of the string, which corresponds to the radius of the cut path of the cutting element, in the first row, is larger than the length of the string in the second row  125 . This design allows for the rpm of the cutting elements  100  in the first row to be greater than that of the cutting elements  100  in the second row  125 . In this manner, the first row acts as a rough cutting row that can handle the thicker vegetation first encountered, while the second row acts as a finish or final cutting row that completes the cutting of the vegetation of the strings  105 . A preferred length corresponding to a cutting radius in the first row  120  is 6 inches, while a preferred length of the strings  105  corresponding to a cutting radius in the second row  125  is 4¼ inches. 
     The height of the cutting elements  100  in the first row  120  is higher than that of cutting elements  100  in the second row  125  in relation to a cutting surface. Again, this allows for a leading rough-cut by the cutting elements  100  in the first row  120  and a finish cut by the cutting elements  100  in the second row  125 . 
     With reference to FIG. 3, it can be seen that the cutting radiuses of the cutting elements  100  in the first row  120  overlap the cutting radiuses of the cutting elements  100  in the second row  125 , such that if one string  105  is broken, the integrity of the cutting path would be maintained by the cutting string  105  in the front  120  or back row  125 . As referenced above, the mandrel shafts  65  adjacent to one another rotate in opposite directions, such that the cutting elements  100  of adjacent mandrel shafts  65  do not interfere with each other. The rotation of the mandrel shafts  65  adjacent to each other in opposite directions also provides for the creation of a turbulence under the housing  10  that will capture and agitate the grass clippings and cut them repeatedly, resulting in a mulching effect. 
     As shown in FIG. 4, the multi-string lawnmower  5  of the present invention may also include a photovoltaic panel  130  attached to the handle  40  that is connected with the battery  45 . The photovoltaic panel  130  would recharge the battery  45  when the lawnmower is exposed to a source of light. 
     It is also envisioned that a number of the multiple string lawnmowers  5  of the present invention may be yoked together and attached to a means of locomotion to provide a larger cut path for farm or municipality type applications. The multiple string lawnmowers  5  may be powered by a single battery from a common source or may be powered by individual batteries. The combination of the yoked lawnmowers may be towed or otherwise moved with any number of vehicles including electric golf carts or the like. 
     While a preferred embodiment is disclosed, a worker in this art would understand that various modifications would come within the scope of the invention. Thus, the following claims should be studied to determine the true scope and content of this invention.