Patent Publication Number: US-2009223475-A1

Title: Implement With Two Hand Interlock

Description:
CROSS REFERENCES TO RELATED APPLICATIONS 
     Not Applicable. 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH 
     Not Applicable 
     TECHNICAL FIELD 
     The present invention relates to the implements, and more particularly to an implement including an engine start interlock. 
     DESCRIPTION OF THE BACKGROUND ART 
     Implements, such as lawn mowers and snow blowers, are typically powered by a prime mover, such as an internal combustion engine. Many of these implements have an electric start, i.e. the engine is started by an electric starter connected to a battery or other electrical source. Current manufacturers include sensors in an ignition circuit actuating the starter to ensure certain conditions are met prior to starting the engine. For example, sensor switches incorporated in the ignition circuit are often used to determine the position of the controls for the power take off (PTO), ground drive, and parking brake. 
     The sensors are provided to ensure the PTO is disengaged and the parking brake is engaged when starting the engine. The goal of these and other sensors is to ensure the implement does not surprise the operator with any unexpected actions when the engine is started. Unfortunately, providing multiple sensors that determine the position of various implement controls complicates the ignition circuit rendering the implement unreliable. Therefore a need exists for a simpler and more reliable implement that will not surprise an operator with any unexpected actions. 
     SUMMARY OF THE INVENTION 
     The present invention provides a simpler and more reliable implement that will not surprise an operator with any unexpected actions by providing an implement that ensures an operator is not inadvertently operating controls while starting the engine. This is accomplished by requiring the operator use two hands to start the engine making it very difficult to engage the PTO or ground drive. 
     One embodiment of the present invention is an implement including an internal combustion engine. An electric starter is provided to start the internal combustion engine. An ignition circuit actuates the electric starter. A first normally open switch forming part of the ignition circuit is mounted on the implement at a first position and must be held closed by an operator for the ignition circuit to actuate the electric starter. A second normally open switch forming part of the ignition circuit is mounted on the implement at a second position and must be held closed by an operator for the ignition circuit to actuate the electric starter. The first position is spaced from the second position a sufficient distance to prevent an operator from closing both the first normally open switch and the second normally open switch with a single hand. 
     The advantages of the invention will appear from the following description. In the description, reference is made to the accompanying drawings which form a part hereof, and in which there is shown by way of illustration a preferred embodiment of the invention. Such embodiment does not necessarily represent the full scope of the invention, however, and reference is made therefore to the claims herein for interpreting the scope of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a front right perspective view of an implement incorporating the present invention; 
         FIG. 2  is a top view of the implement of  FIG. 1 ; and 
         FIG. 3  is a schematic drawing of an ignition circuit for the implement of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     As shown in  FIGS. 1 and 2 , an implement  10  is powered by an internal combustion engine  12  mounted on a frame  14 . The frame  14  is supported by a pair of ground engaging drive wheels  16 ,  18  operatively connected to the engine  12  by a transmission. The engine  12  also drives the blades of a lawn mower deck  20  supported by the frame  14 . Although a mower deck  20  is shown, other working devices can be supported by the frame  14 , such as a snow blowing blower, tiller, and the like, without departing from the scope of the invention. 
     Right and left handlebars  22 ,  24  extending rearwardly from the frame  14  include grips  26 ,  28  for grasping by the operator to steer the implement  10 . Forward and reverse control levers  34 ,  36  pivotally mounted proximal the grip  26  on the right handlebar  22  selectively engage the engine  12  to propel the implement  10  in the forward and reverse directions. A PTO lever  38  pivotally mounted on the left handlebar  24  selectively engages the blades in the mower deck  20  with the engine  12  to rotate the blades for cutting grass. 
     A control panel  40  extending between the handlebars  22 ,  24  supports a key switch  42 , an interlock switch  44 , and a throttle control  46 . The key switch  42  and interlock switch  44  form part of an ignition circuit  48 , such as shown in  FIG. 3 . The throttle control controls the flow of fuel to the engine  12 . The control panel  40  is fixed to and supported by the handlebars  22 ,  24 . Of course, the control panel  40  can be fixed to any part of the implement  10  at any location without departing from the scope of the invention. 
     The ignition circuit  48  includes the key switch  42 , interlock switch  44 , a starter solenoid  50 , and a battery  54  (also shown in  FIGS. 1 and 2 ). Of course, other interlocks or contacts may be in the ignition circuit  48 , such as interlock switches requiring the PTO is disengaged, the drive transmission(s) is disengaged, and the like, without departing from the scope of the invention. Actuation of the starter solenoid  50  engages an electric starter  52  with the engine  12  and energizes the electric starter  52  to turn, and thus start, the engine  12 . Importantly, actuation of the starter solenoid  50 , and thus the electric starter  52 , requires that both the key switch  42  and interlock switch  44  are closed. 
     The interlock switch  44  is preferably a normally open momentary rocker switch having an open position and a closed position. The interlock switch  44  is biased away from the closed position and must be held in the closed position by the operator to maintain the switch  44  in the closed position when starting the engine  12 . Although a momentary rocker switch is disclosed, any normally open switch biased away from a closed position, such as a keyed switch, push button switch, and the like can be used without departing from the scope of the invention. 
     The key switch  42  is a normally open standard keyed ignition switch and requires turning a key inserted in a key hole to close the key switch  42 . Preferably, the key switch  42  is biased away from the closed position requiring the operator hold the key in a turned position to keep the switch  42  closed when starting the engine  12 . Although a key switch  42  is disclosed, any normally open switch biased away from a closed position, such as a momentary rocker switch, push button switch, and the like, can be used without departing from the scope of the invention. 
     Advantageously, the key switch  42  and interlock switch  44  are mounted on the control panel  40  at positions a sufficient distance from each other to prevent the operator from actuating, i.e. closing, both switches  42 ,  44  using one hand. As a result, two hands are required to start the engine  12 . In particular, one hand must turn the key in the key switch  42  and the other hand must depress the interlock switch  44  to start the engine  12 . As a result, the location of both hands of the operator are known at the time the engine  12  is started. Advantageously, by requiring an operator to use both hands to start the engine  12 , it is very difficult for the operator to inadvertently have the PTO or ground drive engaged when starting the engine  12 . 
     The location and type of the switches determines whether a distance is sufficient to prevent an operator from closing two normally open, operator actuated switches. For example, between three and five inches is sufficient to prevent an operator from actuating both a key ignition switch and a rocker switch mounted on the face of a control panel. Eight inches, however, are required if both switches are rocker switches. Whereas, two inches is sufficient if both switches are key ignition switches. Likewise, overlapping edges of the switches separated by the thickness of the control panel is sufficient for two rocker switches if one rocker switch is mounted to the face of the control panel and the other rocker switch is mounted on the back of the control panel. 
     Preferably, as shown in  FIG. 2 , the key switch  42  is proximal the right handlebar  22  and the interlock switch  44  is proximal the left handlebar  24 . Most preferably, the centerline of the key switch  42  is spaced nine and one-third (9⅓) inches from an edge of the interlock switch  44 . In the embodiment disclosed herein, an edge of the key switch  42  closest to the interlock switch  44  is spaced eight and one-half (8½) inches from an edge of the interlock switch  44  closet to the key switch  42 . However, a key switch  42  spaced at least five (5) inches away from the interlock switch  44  is also a sufficient distance to prevent an operator from closing both the key switch  42  and the interlock switch  44  with a single hand. Of course, the key switch  42  and interlock switch  44  can be mounted anywhere on the implement  10  as long as the switches  42 ,  44  are spaced a sufficient distance to prevent an operator from closing both the key switch  42  and the interlock switch  44  with a single hand without departing from the scope of the invention. 
     In use, the operator starts the engine  12  by inserting a key into the key switch  42  with a right hand and depressing the interlock switch  44  with a left to close the interlock switch  44 . While depressing the interlock switch  44  with the left hand, the operator turns the key in the key switch  42  to close the key switch  42 . Assuming all other contacts, if present, in the ignition circuit  48  are properly closed, the ignition circuit  48  energizes the starter solenoid  50  to actuate the electric starter  52  and start the engine  12 . Of course, the locations of the key switch  42  and interlock switch  44  can be different from that shown in the  FIGS. 1 and 2 , such that the operator closes the key switch  42  using the left hand and the right hand closes the interlock switch  44  without departing from the scope of the invention. 
     While there has been shown and described what is at present considered the preferred embodiment of the invention, it will be obvious to those skilled in the art that various changes and modifications can be made therein without departing from the scope of the invention defined by the appended claims.