Patent Publication Number: US-2007095040-A1

Title: Ergonomic device and method for steering a riding mower

Description:
TECHNICAL FIELD  
      The present teaching relates in general to riding mowers and more specifically to a device and method for steering a riding mower.  
     BACKGROUND  
      Riding mowers commonly provide a steering wheel to manually control the direction of the mower. For fixed position steering wheel applications, access for the operator to a driver&#39;s seat is provided between the seat and the steering wheel, which generally does not provide flexibility for significantly adjusting the steering wheel position for operator comfort.  
      In some designs, the steering wheel is connected to an articulated post which can be swung toward and away from the driver. The articulated post design allows the entire steering wheel and post to be moved out of the operator&#39;s path to access or dismount the mower. Known articulated post designs also allow the operator to adjust the steering wheel location for comfort and for access/egress from the mower. Drawbacks of known articulated post designs include increased cost and complexity to rotatably mount the articulated post and the general lack of access to mower components on the side where the post is mounted.  
      Riding mower steering wheels are commonly large enough for two-hand operation, to create enough force by the operator to manually control the direction of the mower. Drawbacks of using large handwheels are the increased number of rotations required from stop to stop which effects turning speed, and the interference with access to and egress from the mower inherent with a larger handwheel.  
     SUMMARY  
      According to several embodiments, a steering system positionable proximate to a seat includes an arm rest extension rotatably connectable to a seat arm rest. A hinge device permits at least upward and downward rotation of the arm rest extension and temporarily fixing a plurality of rotation orientations. A steering wheel is rotatably mounted to the arm rest extension. The steering wheel has a diameter adapted for single handed rotation by an operator. The hinge device is positioned to correspond to an operator wrist location and is rotatable a least upward and downward to accommodate a desired wrist angle with respect to the arm rest.  
      According to other embodiments, a drive-by-wire control device is connectable to the steering wheel. The drive-by-wire control device is adapted to convert an angular rotation of the steering wheel into an electrical signal. The electrical signal is used to control an operating speed of an electric motor used to rotate a steerable wheel.  
      According to still other embodiments, a selector switch is operable to select between a first and a second operating ratio of the steering wheel. The first operating ratio corresponds to a first quantity of steering wheel turns selectable for a mower cutting operation. The second operating ratio corresponds to a second quantity of steering wheel turns which is greater than the first quantity of steering wheel turns. The second operating ratio is selectable for a mower transfer operation.  
      According to still other embodiments, a method for steering a riding mower includes a step of positioning a steering wheel on a first handed-side of a seat, the steering wheel including a diameter adapted for single handed engagement by an operator. The method also includes a step of rotating the arm rest extension to a desired rotation angle with respect to the arm rest. The method further includes a step of steering the riding mower using a single-handed operator operation.  
      Further areas of applicability of the present teachings will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating various embodiments, are intended for purposes of illustration only and are not intended to limit the scope of the teachings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The various embodiments will become more fully understood from the detailed description and the accompanying drawings, wherein:  
       FIG. 1  is a front perspective view of a riding mower having an ergonomic device and method for steering a riding mower according to various embodiments;  
       FIG. 2  is a side elevational perspective view of the riding mower of  FIG. 1 ;  
       FIG. 3  is a side elevational view of the riding mower of  FIG. 1 ;  
       FIG. 4  is a side elevational view of a riding mower seat having the ergonomic device according to various embodiments; and  
       FIG. 5  is a side elevational view of a riding mower of several additional embodiments. 
    
    
     DETAILED DESCRIPTION  
      The following description of several embodiments is merely exemplary in nature and is in no way intended to limit the teachings, their application, or uses. While the mower described herein will be described generally as a riding mower, the teachings herein are equally applicable to all riding mowers, including but not limited to, greens, fairway, commercial landscape, reel, or rotary riding mowers.  
      Referring generally to  FIG. 1  and according to various embodiments, a riding mower  10  includes a steering system  11  supported by a mower frame  12 . A structural assembly  14  supports a seat  16  and a power unit to be described later. A seat support frame  18  is positioned between structural assembly  14  and seat  16  to support seat  16 . Seat  16  is adjustable in each of a forward and rearward direction using a seat adjustment device  20 .  
      A compartment cover  22  covers a rearward section of structural assembly  14 . A pair of drive wheels, including a first drive wheel  24  and a second drive wheel  26  provide rotatable propulsion for riding mower  10  in either of a forward or a rearward direction. A steerable wheel  28  is provided at the rear of lower frame  12 . Riding mower  10  further includes each of a first reel cutting deck  30 , a second reel cutting deck  32 , and a third reel cutting deck  34 . Each of the first, second and third reel cutting decks,  30 ,  32 ,  34  include a reel blade assembly  36 . It will be apparent to a person of skill in the art that the reel-type cutting decks can be replaced by other known cutting assemblies including rotary blade cutting assemblies without departing from the scope of the present invention.  
      A support post  38  extends from one side of seat  16 , and according to some embodiments, from a right side. The “sides” referred to herein for riding mower  10  are identified for convenience as a right side and a left side with respect to an operator seated in seat  16  and facing forward. Support post  38  supports a controller  40 . Controller  40  includes a plurality of controls  42  and a steering ratio selector switch  44 . Controls  42  can be switches, knobs, or the like used to control the cutting height of each of the reel blade assemblies  36 , as well as to select between cutting and non-cutting positions for each of the first, second and third reel cutting decks  30 ,  32 ,  34 . An operator using controls  42  can also select a forward or reverse operating direction for riding mower  10 . An arm rest  46  is rotatably connected to seat  16 . Arm rest  46  includes an arm rest extension  48  which is rotatably connected to a distal end of arm rest  46  and positioned to approximately a hand location of the operator. A steering wheel  50  is rotatably supported by arm rest extension  48  which is rotated by the operator to control the direction of riding mower  10 . In some embodiments, steering wheel  50  also includes a speed knob  52  for rapidly rotating steering wheel  50 .  
      In further embodiments, steering wheel  50  has a diameter of approximately 5 inches (12.7 cm). The term “diameter” as used herein is intended to include shapes such as but not limited to circular, oval, polygonal and other geometric shapes measurable either by a diameter (or radius), or by maximum span dimension if steering wheel  50  is not circular. It is desirable to minimize the diameter of steering wheel  50  to maximize the accessibility of an operator for gaining access to or exiting from seat  16 . It is therefore desirable to maintain the diameter of steering wheel  50  substantially equal to or less than 5 inches (12.7 cm). Diameters for steering wheel  50  larger than 5 inches (12.7 cm) can also be used including diameters up to approximately 7 inches (17.8 cm). The location of steering wheel  50  is also selected to promote single-handed operation of steering wheel  50  by an operator of riding mower  10 . In the embodiments shown in  FIG. 1 , arm rest  46  is positioned on a right-hand side of seat  16 . The arm rest position is not limited to any side of seat  16 , therefore arm rest  46  can also be positioned on a left-hand side of seat  16 .  
      Arm rest extension  48  is connected to structure such as arm rest  46  or similar structure connected to seat  16  such that arm rest extension  48  with steering wheel  50  is directly translatable in either a forward or rearward direction if seat  16  is adjusted in either the forward or rearward direction. This ensures that steering wheel  50 , once adjusted to a desirable location by the operator, be retained in the same orientation relative to the operator even if seat  16  is subsequently adjusted forward or rearward during use of riding mower  10 . Support post  38  with controller  40  mounted thereon in some embodiments is also connectable to structure of seat  16  which translates with any forward or rearward motion of seat  16 , similar to arm rest extension  48 . This ensures that controller  40  is retained in a similar orientation to arm rest extension  48  and steering wheel  50  for ease of access to the plurality of controls  42  and steering ratio selector switch  44  by the operator.  
      To permit displacement of seat  16  and support post  38  with respect to structural assembly  14 , a flexible wiring harness  54  is provided to accommodate relative displacement between support post  38  and structural assembly  14  and therefore allows frequent repositioning of seat  16 . A similar flexible wiring harness (not shown) is provided within arm rest  46  to provide electrical communication for operation of steering wheel  50 . As referred to herein, a forward direction is defined as an operator facing direction or motion of seat  16  toward first and second drive wheels  24 ,  26 . A rearward direction is defined as the direction from seat  16  toward steerable wheel  28  or a motion of seat  16  toward steerable wheel  28 .  
      Referring generally now to  FIG. 2 , lower frame  12  further includes a first frame member  56  and a generally parallel second frame member  58 . First and second frame members  56 ,  58  support a foot rest platform  60  having one or more pedals  62  which are displaceable relative to foot rest platform  60 . Pedals  62  are known in the art and can include items such as a throttle control pedal and a break pedal, and can further include a clutch pedal. First and second frame members  56 ,  58  also support a seat support structure  64  which also supports seat  16  from seat support frame  18 . In some embodiments, first and second frame members  56 ,  58  further support a power unit  66  which in one example is a gasoline powered reciprocating engine. For the gasoline powered reciprocating engine embodiments, a fuel tank  68  is also provided. Power unit  66  can also be one or more batteries (not shown) together with an electric drive motor operable to electrically power riding mower  10 .  
      A steering drive motor  70  supported by mower frame  12  is coupled using a gear drive assembly  72  to a steering yoke  74  for rotatably positioning steerable wheel  28  in direct response to electrical signals generated when rotating steering wheel  50 . A forward-most edge of seat  16  defines a plane  78 . According to several embodiments, a forward-most edge of either controller  40 , arm rest extension  48  and/or steering wheel  50  are maintained substantially parallel to, or rearward of plane  78  to maximize operator access to seat  16 . A second arm rest  76  can also be provided for seat  16  on an opposed side of seat  16  from arm rest  46 . Second arm rest  76  can be rotatably mounted to seat  16  and positioned between the stowed or upward position shown in  FIG. 2  and an extended or substantially horizontal position similar to arm rest  46  (not shown). Components of steering system  11  are maintained substantially parallel with or rearward of plane  78  to maximize access by an operator to seat  16  and for operator egress from seat  16  from either side of riding mower  10 , without the need to move arm rest  46 , second arm rest  76 , or steering wheel  50  out of the entrance or egress path of the operator. Further, because controller  40 , arm rest  46 , arm rest  76  and steering wheel  50  each move in direct response to motion of seat  16 , operator access to seat  16  is provided for any position of seat  16 .  
      As best seen in reference to  FIG. 3 , to maintain the relative position of controller  40  with respect to seat  16  and arm rest  46  (only partially shown in  FIG. 3  for clarity), a support tube  80  is connected using a fastener assembly  82  to a sliding seat frame  84 . Sliding seat frame  84  in turn is slidably mounted to seat support frame  18 . Seat  16 , arm rest  46 , controller  40  and support tube  80  are each directly or indirectly connected to sliding seat frame  84  and therefore move in unison with sliding seat frame  84  and seat  16 . In other embodiments, fastener assembly  82  is a rotatable fastener assembly allowing rotation of support tube  80  about an access of rotation  85  defined by fastener assembly  82 . When support tube  80  is rotated in addition to arm rest  46 , further increased access to seat  16 , as well as increased access to sliding seat frame  84  and seat support frame  18  for maintenance is provided.  
      In some embodiments, an electrical power transfer unit  86  is provided to control electrical signals and electrical power for controller  40 , steering wheel  50  and/or steering driving motor  70 . A voltage and/or current applied to steering drive motor  70  rotates steerable wheel  28  about an axis of rotation  88 . Because riding mower  10  is operable for both slower speed cutting operation as well as faster speed transfer operation (with the cutting units inoperable and generally stowed), steering ratio selector switch  44  is provided to allow the operator to select between different turning ratio signals for each of a cutting operation and a mower rapid transfer operation. Selecting different turning ratio signals controls for example the sensitivity of steering wheel  50  to operator rotation. For rapid transfer operation, reduced sensitivity is desirable, and for cutting operation increased sensitivity is desirable. Steering sensitivity can be adjusted by changing the total rotational range of steering wheel  50 .  
      Referring now generally to  FIG. 4 , an exemplary side elevation view of seat  16  identifies an arc of rotation α for arm rest  46 . In some embodiments, arc of rotation α ranges from approximately 90 to 110 degrees, preferably exceeding 90 degrees to stabilize arm rest  46  in a stowed position. Arm rest  46  is rotatably connectable to seat  16  using a rotation joint  90  and is positionable between the stowed position (shown in phantom) and an extended position where steering wheel  50  is accessible for use by the operator. Arm rest  46  can further include a pad member  92  to support a forearm of the operator. A hinge member  94  is positioned proximate to a wrist location of the operator. Hinge member  94  allows rotation of arm rest extension  48  about at least an arc of rotation β relative to arm rest  46 . A friction lock knob  96  is provided for the operator to select a comfortable arc of rotation β and temporarily frictionally engage arm rest extension  48  to arm rest  46  at the desired angle β.  
      Although arc of rotation β is shown below a horizontal plane defined by pad member  92  of arm rest  46 , other embodiments are not limited to this downward direction arc of rotation β. Arc of rotation β can also include rotation of arm rest extension  46  above the plane defined by arm rest  46  at the discretion of the operator. Still further, hinge member  94  can include a “ball type” hinge, which permits rotational movement of arm rest extension  48  about multiple planes of rotation in addition to arc of rotation β.  
      The configuration shown for friction lock knob  96  is discretionary with the designer. The size and/or diameter of friction lock knob  96  is minimized to provide maximum unrestricted access of the operator to steering wheel  50  and speed knob  52  for full rotation of steering wheel  50 . A lever, a rounded knob, or a similar device made of a polymeric or metal material can be used for friction lock knob  96 . A forward-most point  99  of arm rest extension  48  is preferably restricted by a length of arm rest  46  so that forward-most point  99  is positioned either parallel with or rearward of plane  78  as previously described. Through the use of seat adjustment device  20 , sliding seat frame  84 , together with seat  16  and arm rest  46 , are collectively movable in either a forward direction “A” or a rearward direction “B” relative to seat support frame  18 . Seat support frame  18  is rigidly supported to structural assembly  14  which is itself rigidly supported to mower frame  12 .  
      A rotational sensor  98  is supported by arm rest extension  48  and connectable to steering wheel  50 . Rotational sensor  98  in some embodiments of the invention produces a voltage output and current for a given number of revolutions per minute of steering wheel  50 . For example, rotational sensor  98  can provide a five volt DC output signal for every one thousand revolutions per minute of steering wheel  50 . Rotational sensor  98  does not generate a voltage/current signal when steering wheel  50  is stationary. The output signal voltage and current of rotational sensor  98  can be connected to controller  40  and/or to electrical power transfer unit  86 , to use the output signal to control an electrical current to steering drive motor  70 , which in turn rotates steerable wheel  28 . It should be apparent that multiple types of rotational sensors  98  can be used within the scope of the present invention.  
      By using the electrical output signal of rotational sensor  98 , a “drive-by-wire” system is provided for steering system  11  which eliminates the need for a large diameter (greater than approximately 7 inches (17.8 cm)) two-handed steering wheel for riding mower  10 . A reduction in diameter for steering wheel  50  and single-handed operation of steering wheel  50  are therefore provided for riding mower  10 . Steering wheel  50  can also be positioned to either a right or a left side of seat  16  for single-handed operation by the operator. In one or more embodiments, rotational sensor  98  is available from the Pittman Corporation and is also known as a tach generator.  
      To accurately control riding mower  10  during the rapid transfer condition, a slow ratio steering position of steering ratio selector switch  44  is selected. Fast or slow ratio steering is defined herein as the number of turns of steering wheel  50  required from lock-to-lock. Slow ratio steering reduces steering sensitivity of steering wheel  50  by increasing the number of turns of steering wheel  50  from lock-to-lock. Reducing steering sensitivity prevents minor changes in position of steering wheel  50  from creating a rapid steering change in riding mower  10 . For example only, slow ratio steering for riding mower  10  can provide for two complete turns or rotations of steering wheel  50  from lock-to-lock.  
      In contrast, when riding mower  10  is used in the cutting operation with each of first, second and third reel cutting decks,  30 ,  32 ,  34  operational for grass cutting, steering wheel  50  provides complete turning capability of riding mower  10  with fewer complete turns. For example only, the quick ratio steering selection position of steering ratio selector switch  44  can provide a single turn lock-to-lock rotation of steering wheel  50 . This permits an operator to rapidly turn riding mower  10  with reduced rotational motion of steering wheel  50  when riding mower  10  is operated during the generally slower speed cutting operation, for both forward and reverse directions. The difference between fast and slow ratio steering can be provided for example by switching to different windings of rotational sensor  98 , or by changing the output voltage.  
      Referring now to  FIG. 5 , in some embodiments, a riding mower  100  includes a steering system  101 . Riding mower  100  provides a frame  102  supporting a seat  104  and a grass clipping collection housing  106 . Similar to riding mower  10 , riding mower  100  includes a steerable wheel  108  rotatably supported by a yoke  110 , and a pair of drive wheels  112  (only one is visible in this view). At least one forward positioned cutting deck  114 , and a mid positioned cutting deck  116  are mounted to frame  102  for grass cutting operations of riding mower  100 . A power unit  118  is suspended from frame  102  by a power unit support frame  120 .  
      An arm rest  122  is rotatably coupled to seat  104  and is rotatable about an arc of rotation  124  from the extended position shown to an upright or stowed position (not shown). A controller  126 , similar to controller  40 , is structurally supported by a sliding seat support frame  128 . An arm rest extension  130  is also connected to sliding seat support frame  128  by an extension support assembly  132 . Arm rest extension  130  rotatably supports a steering wheel  134  similar to steering wheel  50 . Arm rest extension  130  is rotatably supported to extension support assembly  132  similar to the rotatable support of arm rest extension  48  to arm rest  46 . This permits an angle of rotation of steering wheel  134  and arm rest extension  130  to be varied with respect to arm rest  122 .  
      Steering system  101  primarily differs from steering system  11  in that arm rest extension  130  and controller  126  are commonly supported independent of arm rest  122 . Rotation of arm rest  122  about an arm rest axis of rotation  123  is therefore independent of any motion, or angular orientation, of steering wheel  134 . It is desirable, however, that a distal end of arm rest  122  be positioned relative to a wrist of the operator and the angular orientation of steering wheel  134  be adjustable to suit the desired angle for operation of steering wheel  134  at the discretion of the operator, similar to the angular orientation provided by arc of rotation β for steering wheel  50 . Similar to steering system  11 , controller  126 , arm rest extension  130  and steering wheel  134  of steering system  101  can be positioned as far forward as a plane  136  defined by a forward-most edge of seat  104 , or positioned rearward of plane  136 .  
      A steering system as herein described provides several advantages, including a “reduced diameter” steering wheel for steering a riding mower. The term “reduced diameter” as referred to herein is generally defined as a steering wheel having a maximum span (if not round) or diameter which is capable of being spanned by a single hand of an operator. For this purpose, a diameter of approximately 5 inches (12.7 cm) or smaller is assumed. Steering systems as herein described are electrically power assisted. This eliminates the need for a two-handed steering wheel to provide the amount of torque to steer the riding mower. A tach generator or similar device is provided to convert rotational motion of the steering wheel to an electrical signal, which is used to actuate an electric motor to rotate the steerable wheel. An angular orientation of the steering wheel is selectable by the operator for greatest operating comfort and relates to a bend angle of the operator&#39;s wrist. The operator can also select between a transport operation condition and a cutting operation condition, each using a different total lock-to-lock quantity of turns of the steering wheel. The reduced diameter steering wheel defined herein also allows the total assembly of the steering wheel and arm rest extension to be retained parallel with or rearward of a plane defined by a forward edge of the seat. This maximizes accessibility to or from the seat from either side of the riding mower by the operator.  
      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.