Abstract:
A motor for powering a cutting unit in an electric mower. The motor is mounted above the cutting unit. A second motor is provided to drive one or more accessories and is also mounted above the cutting unit. The motors are symmetrically placed toward opposite ends of the cutting unit. The second motor acts as a counterbalance to the first, so the cutting unit has similar weight on both of its ends. This eliminates the need for a torsion spring counterbalance system, allows increased mobility of the cutting unit, and facilitates servicing of the cutting unit.

Description:
This application is a divisional of application Ser. No. 08/800,713, filed Feb. 14, 1997 entitled Dual Motor Drive System for Electrically Powered Mower, now U.S. Pat. No. 6,082,082 issued on Jul. 4, 2000. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates in general to electrically powered mowers and relates more particularly to such a mower with a dual motor drive system to power the cutting blades and accessories. 
     2. Prior Art 
     In the conventional reel mower, each cutting unit is powered by its own reel motor. The reel motor is mounted to one side of the frame of the cutting unit, and drives the reel assembly through a coupling. In an electrically powered mower, the electric motor needed to supply sufficient torque to the reel is quite large, typically 4.0″ in diameter and between 6 to 8″ long. The large size of this side mounted reel motor may create problems with ground clearance on undulating terrain, clearance between the reels, and clearance between the motor and the fringe cut (the grass bordering the green). For example, since the height of the grass on the green is typically 0.10″ to 0.18″ and the height of the grass in the area around the green is 0.30″ to 0.75″, mowing the edge of the green causes the side mounted reel motor to overhang the fringe area adjacent the green. The large reel motor may not clear the taller grass in the fringe area, thus causing undesirable compaction. 
     A side mounted motor typically also has problems with side clearance. Since the side mounted motor usually extends from the side of the reel by around 6″ to 8″ inches, if the side mounted motor is mounted on the inside of one of the front reels, the clearance between the two front reels is required to be at least the length of the side mounted motor, thereby limiting closer placement of the reels. Similarly, if the side mounted motor is on the outside of one of the forward reels, it extends an extra 6″ to 8″ from the side of the reel and thus the entire mower, preventing the mower from making a close cut near bushes, fences, or other obstructions. 
     Another problem with a side mounted reel motor is that it must be counterbalanced so that the reel will be level and provide an even cut. Prior art greens mowers use a torsion spring counterbalance system, or simply add weight to the other side of the reel to counterbalance the weight of the motor. The total weight of the reel-motor system is increased, causing undesirable compaction of the grass. 
     Finally, when a reel on a side mounted mower needs service, the side mounted motors must be removed from the reel in order to access and to service the reel. 
     One prior art mower embodying the above-mentioned drawbacks is described in U.S. Pat. No. 5,406,778 to Lamb. 
     There is a need, therefore, for a reel mower drive system that does not have the above drawbacks. 
     SUMMARY OF THE INVENTION 
     The present invention provides a unique drive system for a mower cutting unit. The motor is mounted above the cutting unit and is belt driven to the cutting unit. A second motor maybe added to drive an optional groomer mechanism or other accessory. The motors are arranged symmetrically above the cutting unit rather than to the side of the cutting unit. The second motor acts as a counterbalance to the first motor, so the cutting unit has similar weight on both sides which eliminates the need for a counterbalance system found in the prior art. Because the motor does not extend from the side of the cutting unit, the cutting unit and the entire mower of the present invention is more mobile. 
     One object, therefore, of the present invention is to provide a motor for a cutting unit that does not interfere with ground clearance or side clearance of the mower or of the cutting units. 
     Another object of the present invention is to eliminate the need for an additional, complicated counterbalance system for the motor that powers the cutting unit. 
     A further object of the present invention is to facilitate the adjustment and sharpening of the cutting unit by simplifying access to the cutting unit for service. 
     These and other objects, features, and advantages of the present invention will be apparent from the accompanying drawings and from the detailed description that follows. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention is illustrated by way of example and not limitation in the figures of the accompanying drawings, in which like references indicate similar elements and in which: 
     FIG. 1 is general view of an electric greens mower in accordance with the present invention; 
     FIG. 2 shows a prior art cutting unit system with the motor mounted to the side of the cutting unit; 
     FIG. 3 shows a dual motor system in accordance with the present invention with the placement of the motors above the reel; 
     FIG. 4 a  shows a dual motor system in accordance with the present invention with the reel drive pulleys and the reel drive belt; 
     FIG. 4 b  shows the dual motor mounting in accordance with the present invention; 
     FIG. 4 c  shows a dual motor system in accordance with the present invention with the drive motor mounting cover in place; 
     FIG. 5 a  shows the accessory motor mounting in accordance with the present invention; 
     FIG. 5 b  shows the accessory motor drive system including the accessory drive pulleys and the accessory drive belt in accordance with the present invention; 
     FIG. 5 c  shows the accessory motor mounting including the groomer drive mounting; 
     FIG. 5 d  shows the accessory motor drive system including the groomer pulleys and the groomer belt; 
     FIG. 5 e  shows the accessory motor mounting cover and the groomer mounting cover; and 
     FIG. 5 f  shows the accessory motor drive system incorporating a further accessory drive pulley system. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In the Figures, a dual motor drive system  66  is provided for an electric mower  10 . FIG. 1 is a general illustration of an electric mower  10  in accordance with the present invention. Although the invention is described with respect to the preferred embodiment, those skilled in the art will recognize that other versions of the mower embodying the current invention are possible and that the invention is not limited to one specific embodiment. 
     In the embodiment shown in FIG. 1, the riding greens mower  10  of the present invention includes three wheels  20 ,  21  and  22 . The two front drive wheels  20  and  21  are powered by electric drive motor  30 . The rear wheel  22  is positioned behind and between the two front drive wheels  20  and  21  and is pivotable to steer the mower  10 . The cutting units  60 ,  61 , and  62  are positioned ahead of each of the wheels  20 ,  21 , and  22  respectively. The cutting units  60 ,  61  and  62  are ideally reel cutting units, but can also be rotary cutting units or other types of cutting units. The cutting units  60 ,  61 , and  62  are mounted on lift arms  1 ,  2  and  3 . The operator selectively raises and lowers the lift arms  1 ,  2  and  3  depending on which cutting units  60 ,  61 , and  63  the operator wishes to use. When in the lowered or operative position, the lifts  1 ,  2  and  3  allow free vertical motion providing for an even cut over an undulating surface such as a golf course green. The electric drive motor  30  which drives the mower  10 , is powered by the battery set  40  (not shown) located underneath a hood  42  and is controlled by the controller  50 . 
     FIG. 2 shows a prior art reel and motor assembly. The side mounted motor  430  is mounted to the reel  400 . The reel  400  is connected to the frame  412  of the mower  10  via a lift arm assembly  1 . A torsion spring  450  is positioned over the lift arm pivot tube (not shown) and groove pin  453  in swivel housing  455 . The torsion spring  450  is tightened to a point that balances the side  470  of the reel  400  having the side mounted motor  430  with the other, lighter side  480  of the reel  400 . An electric actuator  410  controllably raises and lowers the reel  400  with respect to the ground at the operator&#39;s command. The torsion spring  450  is part of the counterbalance system used in the prior art for the reel  400  to provide an even cut to the grass. Because the side mounted motor  430  makes the side  470  of the reel  400  to which it is attached heavier than the opposing side  480 , either a weight equal to that of the side mounted motor  430  is symmetrically applied to the opposing side  480 , or the torsion spring  450  described above is used to equate the weight applied to each side  470  and  480  of the reel  400  to achieve an even cut. Adding. this extra weight or counterbalance system increases the overall weight applied by the reel  400  thus causing undesirable compaction of the grass and decreasing the active life of the cutting unit. 
     Another drawback of the reel and motor system of the prior art shown in FIG. 2 is the small ground clearance allowed by the side mounted motor  430 . For example, in an electrically powered mower, the size of the side mounted motor  430  to supply sufficient torque to the reel must be quite large and long, typically 4.0″ in diameter and between 6-8″ long. In FIG. 2, the distance between the bottom of the side mounted motor  430  and the ground is represented by the letter D. Because the height of the grass on the green is typically 0.10″ to 0.18″ and the height of the grass in the area around the green (called the fringe area) is around 0.30″ to 0.75″, mowing the edge of the green causes the side mounted motor  430  to extend over the fringe area. The clearance D of the side mounted motor  430  to the ground must be greater than the height of the fringe cut. If the clearance D is less than the height of the fringe cut, the grass in the fringe area will be compacted. 
     The side mounted motor  430  of the prior art shown in FIG. 2 typically also has problems with side clearance. As mentioned above, the side mounted motor  430  usually extends from the side of the reel  400  by around 6″ to 8″ inches, represented by length L in FIG.  2 . If the side mounted motor  430  is mounted on the inside of one of the front reels, the clearance between the two front reels is required to be at least the length of the side mounted motor  430 , thereby limiting closer placement of the reels  400 . Similarly, if the side mounted motor  430  is on the outside of one of the forward reels, it extends an extra length L from the side of the reel  400  and thus, from the entire mower  10 , preventing the mower  10  from making a close cut near bushes, fences or other obstructions. 
     FIG. 3 is a detailed drawing of the dual motor system  66  of the current invention. As an example, cutting unit  60  in FIG. 1 will be explained. Those skilled in the art, however, will recognize that other cutting units on the mower  10  would be constructed in a similar fashion. To aid in describing the construction of the dual motor system  66 , the cutting unit blades have been removed from the dual motor system of FIG.  3 . Cutting unit shaft  100  extends from one end of the cutting unit  60  to the other. Side plates  102  and  104  hold a rear roller (not shown), a bedknife (not shown) and support the motor mountings  112  and  114 . A cross bar  106  is located in front of the cutting unit shaft  100  and is used to support the side plates  102  and  104 . Motor mountings  112  and  114  located at either end of the cutting unit shaft  100  support the electric motors  116  and  118  above the cutting unit  60  of the dual motor system  66 . Wire groupings  122  and  124  are shown extending from each motor  116  and  118 . These wires  122  and  124  connect the motors  116  and  118  to the controller  50  or to the battery  40  (FIG.  1 ). 
     A lift yoke  126  operates to raise and lower the cutting unit  60  when necessary. The lift yoke  126  couples the lift  1  to the cutting unit  60 . Lifts  1 ,  2  and  3  are controlled by the operator who selectively chooses which cutting unit  60 ,  61  and/or  62  he desires to operate. If the operator determines the use of the cutting unit  60 ,  61  and/or  62  is no longer necessary, because he is transporting the mower  10  to another location or for other reasons, he can direct the respective lift  1 ,  2  and/or  3  associated with that cutting unit  60 ,  61  and/or  62  to raise the cutting unit. Similarly, if the desired cutting unit(s)  1 ,  2 , and/or  3  are in the raised position and need to be lowered, the operator directs the respective lift(s)  1 ,  2 , and/or  3  to lower the cutting unit  60 ,  61 , and/or  62 . The lift yoke  126  also has a grass catcher hook  128  which when connected to an optional grass catcher (not shown) operates to raise the grass catcher along with the cutting unit  60 . Lift yoke  126  is connected to the cutting unit  60  at each end to pivots  130  and  132 . Pivot  134  attaches the center of the yoke  126  to the lift  1 . The cutting unit  60  is thereby attached to the lift  1  via the lift yoke  126  by pivots  130 ,  132 , and  134 . The pivots  130 ,  132 , and  134  work together to allow the cutting unit  60  to travel over bumps and uneven portions of the green while making an even cut. 
     By using two symmetrically placed motor mountings  112  and  114  to mount the motors  116  and  118  that power the cutting unit  60  and any accessories, the counterbalance system of the prior art mowers is no longer necessary. Similarly, by locating both motors above and substantially inside the envelope of the outside edges of the cutting unit  60 , the mower  10  is able to mow tight areas without clearance problems either underneath the cutting units  60 ,  61 , and  62  or to the side of the cutting units  60 ,  61 , and  62  as in the prior art. 
     The dual motor system  66  described thus far is preferred due to its flexibility. The size of each electric motor  116  and  118  in the dual motor drive system is smaller than the size of a single motor if one motor powered all the functions of the cutting unit  60 . Furthermore, as previously described, by placing the each motor  116  and  118  substantially within the envelope of the cutting unit  60  and in symmetrical relationship to each other, the counterbalance systems found in the prior art are no longer necessary. Additionally, the dual motor system  66  provides the ability to drive both the cutting unit  60  and any optional accessories such as a groomer or a brush discussed in more detail below. 
     In some circumstances, however, only one motor per cutting unit may be implemented and still fall within the scope of the present invention. For example, if the operator will not be operating any of the accessory devices available with the dual motor system  66  described above, then one motor located above and substantially within the envelope of the cutting unit  60  still offers many advantages over the prior art side mounted motor  430 . Mounting the motor in this manner eliminates both the ground clearance and the side clearance problems inherent in the prior art. Additionally, mounting the motor above the cutting unit instead of to the side decreases the amount of torque necessary to counterbalance the cutting unit. 
     The closer towards the center of the cutting unit that the motor is mounted, the smaller the counterbalance required. The single motor may also be mounted directly above the center of the cutting unit in one embodiment. In another embodiment for the center mounted motor, power is transferred to the cutting unit at the middle of the cutting unit. In this embodiment, the cutting unit may be divided in the center to receive power from the single motor. 
     Although the motor in the preferred embodiment is placed horizontally above the cutting unit, a motor may also be mounted vertically with respect to the reel and still obtain many of the advantages described above. A vertically mounted motor would still fall within the scope of the preferred embodiment since it would eliminate the ground clearance problems and the side clearance problems found in the prior art. 
     FIGS. 4 a,    4   b  and  4   c  show the drive motor mounting  114  including the power transfer mechanism and the drive motor mounting cover  117 . The power transfer mechanism provides the power connection between the motor  118  and the cutting unit  60 . In FIG. 4 a,  the power transfer mechanism includes the belt  138  that couples an upper pulley  140  to a lower pulley  142 . Upper pulley  140  is connected to drive motor  118  and lower pulley  142  is connected to the cutting unit  60 . In this manner, the power transfer mechanism operatively connects the primary motor  118  to drive the cutting unit  60 . In the preferred embodiment shown in the Figures, the power transfer mechanism includes a dual pulley and belt system. A belt couples the two pulleys thus transmitting power from the drive motor  118  to the cutting unit  60 . The coupling of the power transfer mechanism transmits rotary motion from one pulley to another. However, any power transfer system that conveys power from the primary motor  118  to the cutting unit  60  would fall within the scope of the present invention. Although in the embodiment described above the coupling is a belt, the pulleys could also be connected with a chain or other type of power transfer apparatus. The shaft mechanism includes, but is not limited to, any wheel on a shaft having a crowned or cambered rim for carrying a coupling that can be a belt, a rope or a chain. The power transfer system may also include an interactive gear system comprising interlocking gear drivers. 
     The power transfer mechanism including the belt and pulley structure  138 ,  140 , and  142  is supported by motor mounting  114 . Motor mounting  114  is attached to side plate  104  of cutting unit  60  by bolts or screws or other suitable means at locations  192  through  194 . Adjustments in the tightness of the belt  138  are made at belt take up location  195 . Location  195  is, in one embodiment, a screw that the when turned in one direction stretches the distance between the pulleys  140  and  142  thus tightening the belt  138 . Of course, any other type of tensioning device can be used. When turned in another direction, screw  195  decreases the distance between the pulleys  140  and  142  giving the belt  138  more slack. Motor  118  is mounted to the motor mounting  114  by a plurality of screws or bolts or like attachment means placed through holes  182 ,  184 ,  186  and  188  in the motor mounting  114  and then affixed to the motor  118 . Motor mounting  114  is covered by drive motor mounting cover  117  shown in FIG. 4 c.  Holes  145  through  150  located in the outer periphery of the motor mounting  114  and in corresponding locations in the drive motor mounting cover  117 . The holes  145  through  150  are used to mount the drive motor mounting cover  117  shown in FIG. 4 c.  Drive motor mounting cover  117 , however, should be removably attached so that the pulleys  140  and  142  and the belt  138  can be accessed for cleaning and service. Once again, screws, bolts or other suitable attachment means are used to attach the drive motor mounting cover  117  to the motor mounting  114 . 
     FIG. 4 b  is a perspective view of the drive motor mounting  114  of the present invention. In FIG. 4 b,  the pulleys  140  and  142  and the belt  138  are not shown. The drive motor mounting  114  in conjunction with the drive motor mounting cover  117  forms a substantially closed chamber that functions to keep grass cuttings, moisture, and other debris away from the belt  138  and the pulleys  140  and  142 . As discussed with respect to FIG. 4 a,  the drive motor  118  is mounted to the motor mounting  114  by bolts placed through holes  182 ,  184 ,  186 , and  188  (with  182 ,  184  and  186  shown in phantom). Holes  145  through  150  are used to affix the drive motor mounting cover  117  shown in FIG. 4 c  to the motor mounting  114 . Holes  192  through  194  mount the motor mounting  114  to the side plate  104  of the cutting unit  60  as shown in FIG.  3 . 
     Returning to FIG. 4 c,  in place, bolts, screws or other suitable means attach the drive motor mounting cover  117  to the motor mounting  114  through holes  145 ,  146 ,  147 ,  148 ,  149  and  150 . Lower pulley  142 , as shown in FIG. 4 a,  has external portion  144  that extends beyond the drive motor mounting cover  117 . This external portion  144  of power transfer mechanism  142  is used to power an optional accessory such as a brush (not shown) from the drive motor  118  by employing a second power transfer mechanism similar to that described above, such as by attaching a second belt to the external portion  144  of pulley  142  and to a further pulley attached to the accessory. 
     FIGS. 5 a  through  5   e  depict the accessory motor mounting  112 . FIG. 5 a  shows the accessory motor mounting  112  with the accessory motor  116  removed. Holes  245 ,  246 ,  249 , and  250  are used to mount the mounting cover  115  to the accessory motor mounting  112  in the same manner as for the drive motor mounting  114  and drive motor mounting cover  117  described above with respect to FIGS. 4 a  through  4   c.  Holes  282 ,  284 ,  286 , and  288  are used to mount the accessory motor  116  to the accessory motor mounting  112  in the same manner as described above for the drive motor  118  and the drive motor mounting  114 . Holes  292  through  294  are used to mount the accessory motor mounting  112  to the side plate  102  of cutting unit  60  in the same manner as described for the drive motor mounting  114  and side plate  104  in FIGS. 4 a  through  4   c.  Location  295  is used for belt take up as described with respect to the drive motor mounting  114 . The internal portion of the intermediate shaft  243  is used to mount intermediate pulley  242  and the external portion is used to mount groomer accessory drive pulley  244 . 
     The accessory power transfer mechanism is shown in FIG. 5 b.  The accessory power transfer mechanism provides the power connection between the accessory motor  116  and an optional accessory (not shown). The accessory power transfer mechanism includes both upper pulley  240  and lower pulley  242  having belt  238  operably connecting them. Upper pulley  240  derives power from accessory motor  116  that drives the belt  238  and lower pulley  242  similarly to that disclosed with respect to the drive motor in FIGS. 4 a  through  4   c.  Although the power transfer mechanism disclosed in the Figures is a pulley-belt system, those skilled in the art will understand that other power transfer mechanism also can be used such as described with respect to the drive motor  118 . Holes  245 ,  246 ,  249 , and  250  for mounting accessory motor mounting cover  115  and described with respect to FIG. 5 a  are also shown in FIG. 5 b  as are holes  282 ,  284 ,  286  and  288  for mounting the accessory drive motor  116  and described with respect to FIG. 5 a.    
     In FIG. 5 c  adapter plate  260  is used to install the groomer drive mounting  270  to the accessory motor mounting  112 . The groomer is an optional accessory for the greens mower  10  in accordance with the present invention. The groomer accessory has a front roller and knives that intersect the roller. The roller lifts horizontally growing grasses, and the knives rotate through the roller slots, cutting blades of grass before they can lie down, so grass stands up for a smoother surface. Regular use of the groomer accessory can increase green speed up to 25 percent, control thatch and eliminate grain. The intersecting action of the groomer§s roller and knives is described in detail in U.S. Pat. Nos. 4,494,365 and 4,685,280 both to Lloyd, and U.S. Pat. No. 4,724,662 to Giandenoto and Joray; all three commonly owned by the assignee of this invention. 
     In FIG. 5 c  groomer drive mounting  270  pivots on intermediate shaft  243  bearing (FIG. 5 a ) and is limited in travel by the length of slot  272  in the groomer drive mounting  270 . This allows the operator to lock the groomer accessory into a specified position to provide a fixed height with respect to the cutting unit  60 . Finally, in FIG. 5 c,  accessory motor mounting holes  282 ,  284 ,  286  and  288  described with respect to FIG. 5 a  are shown as are side plate  102  mounting hole  292  and belt take up hole  295 . Also shown are cover mounting holes  245 ,  246 ,  249  and  250 . 
     FIG. 5 d  shows groomer power transfer mechanism. A groomer pulley  274  and groomer drive belt  276  both are mounted on the inside of groomer drive mounting  270 . Groomer drive belt  276  is driven by pulley  244  mounted on the external portion of intermediate shaft  243  attached to lower pulley  242 . Accessory motor drive belt  238  is shown coupling pulley  240  and pulley  242  (shown in phantom) under the groomer drive mounting  270  installed on adapter plate  260 . Groomer drive belt  276  is driven by pulley  244  mounted on the external intermediate shaft  243  which is located externally to the groomer drive mounting  270 . As discussed above with respect to the accessory power transfer mechanism and the drive power transfer mechanism, a belt and pulley system is preferred, but other power transfer mechanism are possible while still remaining within the scope of the present invention. Holes  245 ,  246 ,  249 , and  250  for mounting accessory motor mounting cover  115  and described with respect to FIG. 5 a  are also shown in FIG. 5 d  as are holes  282 ,  284 ,  286  and  288  for mounting the accessory drive motor  116 . 
     FIG. 5 e  shows the accessory motor mounting cover  115  and the groomer drive cover  215 . As with the drive motor mounting cover  117  described with respect to FIGS. 4 a  through  4   c,  the accessory motor mounting cover  115  is installed with screws or bolts or other suitable means passing through holes  214 ,  216 ,  219 , and  220  corresponding to holes  245 ,  246 ,  249  and  250  in accessory motor mounting cover  115 . 
     Referring to FIG. 5 f,  another accessory besides the groomer, such as an optional brush, could be added by attaching another belt  267  to external intermediate shaft portion  244  and a pulley  265  on the additional accessory thereby increasing the uses for the accessory motor  116 . The brush accessory can be a single push brush that penetrates grass, picks up matted growths and allows sun and moisture to stimulate roots. Or the brush can be a fine bristle brush that lifts runners and controls gaining. Such brushes are known in the prior art and are used on mowers owned by the assignee of the present invention. Or, the accessory could be some other kind of turf maintenance equipment generally known in the art. 
     In the foregoing specification, the invention has been described with reference to specific embodiments thereof. It will, however, be evident that various modifications and changes may be made thereto without departing from the broader spirit and scope of the invention as set forth in the appended claims. 
     For example, a riding triplex mower has been disclosed with three wheels and three reels. Mowers could have fewer reels and/or wheels as well as mowers with more reels and/or wheels while still practicing the unique dual motor drive system disclosed above, or the single motor system also disclosed above. A mower having a single cutting unit would also benefit from the above disclosed invention since ground and side clearance would be improved in the same manner as for a three wheeled mower. 
     Other types of cutting units can be used while still keeping within the scope of the current invention. The invention can be implemented with only one motor to power the cutting unit mounted as described above, or with two motors symmetrically mounted as described above. Such a motor would be mounted as the drive motor in the above specification. Or, if only one motor is used it can be mounted in the center of the cutting unit. The invention can be practiced without using any of the optional accessories, or using any one or all of the optional accessories. Furthermore, the invention can be practiced with other accessories besides those specifically disclosed. The specification and drawings are, accordingly, to be regarded in an illustrative rather than in a restrictive sense.