Abstract:
In an agricultural combine, a header float system using a floating header having a frame, a support member supporting the frame from the ground, and a suspension variably supporting the frame from the combine. The suspension comprises a sub-frame removable attaching to the combine, links movably attaching the frame and the sub-frame, and one or more float cylinders moveably supporting the frame from the sub-frame. A float circuit connects to the float cylinder, and a float valve connects the float circuit to a main hydraulic circuit. A pressure sensor connects to the float circuit, and a controller communicates with the float valve and the pressure sensor. The controller maintains pressure in the float circuit at a target value by continuously reading the pressure sensor and commanding the float valve to add or subtract hydraulic fluid in the float circuit until pressure equals the target value.

Description:
FIELD OF THE INVENTION 
   The present invention relates to floating platform and draper-type headers for agricultural combines. The present invention also relates to header float systems and header terrain following systems for agricultural combines. 
   BACKGROUND OF THE INVENTION 
   An agricultural combine is a large machine used to harvest a variety of crops from a field. During a harvesting operation, a header at the front of the combine cuts ripened crop from the field. A feederhouse supporting the header transfers the crop material into the combine. Threshing and separating assemblies within the combine remove grain from the crop material and transfer the clean grain to a grain tank for temporary holding. Crop material other than grain exits from the rear of the combine. An unloading auger transfers the clean grain from the grain tank to a truck or grain cart for transport, or to another receiving bin for holding. 
   Platform headers and draper headers are header types commonly used when harvesting crops such as small grains, peas, lentils, and rice. During a harvesting operation with these header types, it is desirable to maintain a cutting height as low as possible to the ground in order to collect substantially the entire ripe crop from the field. To accomplish this, combines typically employ a header float system or a terrain following system to enable the header to follow the ground over changing terrain without gouging or digging into the soil. 
   Manufacturers have developed a number of such systems over the years. U.S. Pat. Nos. 3,717,995, 3,623,304, and 4,724,661 disclose examples of header float systems using resilient means to suspend the header, thereby reducing the apparent weight of the header, allowing it to lightly skid across the ground over changing terrain. U.S. Pat. Nos. 3,597,907, 4,622,803 and 5,471,823 disclose examples of similar float systems, but using dynamic means to suspend the header. U.S. Pat. Nos. 5,577,373, 6,041,583 and 6,758,029 B2 disclose examples of terrain following systems using dynamic means to position the header, thereby sensing and changing the vertical position of the header to follow changing terrain. 
   SUMMARY OF THE INVENTION 
   The illustrated embodiment presents a floating header design implemented with a draper-type header. The header includes a frame having a conventional configuration, and a floating suspension system extending from the frame having a sub-frame removably attaching to the feederhouse. Float cylinders extending between the frame and sub-frame moveably support the header from the combine. The float cylinders connect to a float circuit, which in turn connects to a main hydraulic circuit on the combine by a float valve. The float valve is an electronically controlled hydraulic valve commanded by a controller. 
   In a first embodiment of a header float system used with the floating header, the controller continuously maintains a target pressure in the float circuit as the float cylinders reciprocate over changing terrain. In header float mode, the system provides constant support of the header by the float suspension as the combine travels through the field. In a second embodiment of a header float system, the controller only initially charges and seals pressure in the float circuit to a target value, with an accumulator acting to maintain target pressure in the float circuit as the float cylinders reciprocate over changing terrain. In a terrain following system, the controller continuously adjusts header height over changing terrain by raising and lowering the feederhouse in response to movement of the floating header suspension. When operating in this mode, the controller maintains the position of the float header for optimal function of the header float system as the combine travels through the field. 

   
     DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a side-view of a combine, showing a floating header having an integrated hydraulic float suspension. 
       FIG. 2  is a partial side-view of the combine, showing the floating header attached at the front of a feederhouse. 
       FIG. 3  is a schematic for a dynamic header float system used with the illustrated floating header. 
       FIG. 4  is a schematic for a resilient header float system used with the illustrated floating header. 
       FIG. 5A  shows a side-view of the combine operating on level ground with an illustrated float system and the floating header. 
       FIG. 5B  shows a side-view of the combine operating on inclining ground with an illustrated float system and the floating header. 
       FIG. 5C  shows a side-view of the combine operating on declining ground with an illustrated float system and the floating header. 
       FIG. 6A  shows a front-view of the combine operating on right-rolling ground with an illustrated float system and the floating header. 
       FIG. 6B  shows a front-view of the combine operating on left-rolling ground with an illustrated float system and the floating header. 
       FIG. 7  is a schematic for a dynamic header terrain following system combined with the illustrated dynamic float system and floating header. 
       FIG. 8  is a schematic for a dynamic header terrain following system combined with the illustrated resilient float system and floating header. 
       FIG. 9A  shows a side-view of the combine operating on level ground with the illustrated dynamic header terrain following system and floating header. 
       FIG. 9B  shows the combine operating on inclining ground with the illustrated dynamic header terrain following system at a first instance. 
       FIG. 9C  shows the combine operating on inclining ground with the illustrated dynamic header terrain following system at a second instance. 
       FIG. 9D  shows the combine operating on declining ground with the illustrated dynamic header terrain following system at a first instance. 
       FIG. 9E  shows the combine operating on declining ground with the illustrated dynamic header terrain following system at a second instance. 
   

   DETAILED DESCRIPTION 
     FIG. 1  illustrates a self-propelled combine  10  commonly used in a grain farming to harvest a variety of crops from a field. An onboard engine powers the combine  10 , while ground engaging wheels  14  support and propel the machine. An operator controls the combine  10  from an operator&#39;s station located in a cab  16  at the front of the machine. An electronic controller  44 , which receives commands from operator input devices and sensors, commands various function of the combine  10 . 
   A feederhouse  20  pivotally attaches at the front of the combine  10 , supporting a header  22  removably attached to the front of the feeder house  20 . A pair of lift cylinders  24  support and articulate the feederhouse  20  from the combine  10 , enabling the raising and lowering of the header  22  relative to the ground. The lift cylinders  24  are single or double acting hydraulic cylinders connected to a main hydraulic circuit  40  by a lift valve  42 . The lift valve  42  is an electronically controlled hydraulic valve commanded by the controller  44 . 
   During a harvesting operation, the combine  10  moves forward through the field with the header  22  lowered to a working height. The header  22  cuts and transfers crop material to the feederhouse  20 , which in turn transfers the crop material into the combine  10 . Once inside the combine, threshing and separating assemblies  26  remove grain from the crop material and transfer it to a grain tank  28  for temporary holding. Crop material other than grain exits from the rear of the combine  10 . An unloading auger  30  transfers the grain from the grain tank  28  to a truck or grain cart for transport, or to another receiving bin for holding. 
     FIG. 2  shows a side-view of a combine  10 , illustrating an embodiment for a floating header configuration  50  for a draper-type header. The header  50  includes a frame  52  having a conventional configuration, the frame  52  supporting a reel assembly  54 , a cutter-bar assembly  56 , and a draper assembly  58 . A floating suspension system  60  extending from the rear of the frame  52  primarily supports the header  50  from the feederhouse  20 , while downward extending support member  62  serves to secondarily support the header  50  from the ground. In the illustrated embodiment, this support member is a skid plate  62  located near the front of the frame  52 , however the portion could also be a gage-wheel (not shown). 
   The suspension system  60  includes a sub-frame  64  removably attaching to the feederhouse  20 , one or more lower links  66 , one or more upper links  68 , one or more float cylinders  70 , a float circuit  72 , and a float valve  74 . The illustrated embodiment employs two parallel lower links  66 , each having a first end  67  pivotally attaching near the bottom of the sub-frame  64 . Each lower link  66  extends forward and has a second end  67 ′ pivotally attaching beneath the header frame  52 . The illustrated embodiment uses one upper link  68 , having a first end  69  pivotally attaching near the top of the sub-frame  64 . The upper link  68  extends forward and has a second end  69 ′ pivotally attaching high on the header frame  52 . 
   In the illustrated embodiment, two float cylinders  70 , one corresponding to each lower link  66 , support the frame  52  from the sub-frame  64 . Each float cylinder  70  has a first end  71  attaching to its corresponding lower link  66  near the lower link first end  67 . Each float cylinder  70  extends upward and has a second end  71 ′ attaching to the header frame  52 . Each float cylinder  70  is a single acting hydraulic cylinder adapted to independently reciprocate over a limit range. Each float cylinder  70  connects to the float circuit  72 , which in turn connects to the main hydraulic circuit  40  via the float valve  74 . The float valve  74  is adapted to selectively add and subtract hydraulic fluid from the float circuit  72 . The illustrated float valve  74  is an electronically controlled hydraulic valve commanded by the controller  44 . The float valve  74  is optionally located either on the floating header  22  or on the combine  10 . 
     FIGS. 3 and 4  show schematics illustrating first and second embodiments,  80 ,  82  respectively, for header float systems used with the floating header  50 . The first embodiment  80  is a dynamic float system, while the second embodiment  82  is a resilient float system. Both header float systems serve to reduce the apparent weight of the header  50  when the working height is such that the header  50  remains in contact with the ground, illustrated in  FIG. 5A . 
   With the apparent weight reduced, the header  50  lightly skids across the ground as the combine  10  moves forward during a harvesting operation, enabling the header  50  to follow changing terrain automatically within the limits of the suspension system  60 . As the header  50  skids forward, the ground urges the header  50  up as slope inclines, illustrated in  FIG. 5B , and gravity urges the header  50  down as slope declines, illustrated in  FIG. 5C . Additionally, the header  50  provides some role angle floatation relative to the combine  10  due to independent reciprocation of each float cylinder  70 , illustrated in  FIGS. 6A and 6B . 
   In the first embodiment  80 , a pressure sensor  84  in communication with the controller  44  connects to the float circuit  72  between the float cylinders  70  and the float valve  74 . Within the cab  16 , operator input devices in communication with the controller  44  allow the operator to control the function of the float system in both embodiments. Operator input devices include, but are not limited to, a float activation device  86  and a float setting device  88 . Examples of float activation devices  86  include toggle switches or push buttons. Examples of float setting devices  88  include analog dial input devices or digital input devices. Not shown, an optional shut-off valve isolates the float cylinders  70  from the hydraulic circuit  40 , allowing for service of the header  50 . Having all of the elements of the first embodiment  80 , the second embodiment  82  further includes an accumulator  90  connecting to the float circuit  72  between the float cylinders  70  and float valve  74 . 
   During a harvesting operation with either embodiment  80 ,  82 , the operator engages the float activation device  86  to operate the header  50  in a float mode, and may also manipulate the float setting device  88  for desired header float response. Once engaged in the header float mode, the controller  44  reads the float setting device  88 , indicating a level of suspension support required of the float system  80 ,  82  by the operator, for example, as percent of header weight or desired pressure in the float circuit. The controller  44  then determines a target pressure in the float circuit adequate to provide the suspension support commanded. 
   To determine the target pressure for the float circuit  72 , the controller  44  may reference data correlating pressure values in the float circuit  72  with suspension support values. This correlated pressure data will vary from header to header as a function of header weight and suspension configuration, and may generate from tables, formulas, or sensor readings. The controller  44  might read the correlated data from a storage device on the header  50 . Data might also be stored in memory internal to the combine, with the controller  44  selecting the appropriate data after sensing the header type attached to the combine  10 . 
   Alternatively, the controller  44  may determine the target pressure for the float circuit  72  by reading the pressure sensor  84  in the float circuit  72  when the header  50  at a height where the skid plates are not in contact with the ground. At such a height, the suspension supports the entire weight of the header, and the pressure in the float circuit indicates a baseline pressure whereby the float cylinders  70  entirely support the header  50 . The controller  44  then determines the target pressure by multiplying the baseline pressure by a factor corresponding to the suspension support indicated from the float setting device  88 . 
   In the first embodiment  80 , the controller  44  continuously compares the target pressure with pressure sensor  84  readings indicating pressure in the float circuit  72 , commanding the float valve  74  to add or subtract hydraulic fluid from the float circuit  72  to maintain pressure sensor  84  readings equal to the target pressure. In this manner, the controller  44  continuously maintains target pressure in the float circuit  72  as the float cylinders  70  reciprocate over changing terrain, providing constant support of the header  50  by the float suspension  60  as the combine  10  travels through the field. To change header float response while operating in header float mode, the operator may further manipulate the float setting device  88  without disengaging the float system. The controller  44  continuously monitors the float setting device  88  for changes, determining and applying new target pressures accordingly. The header float system continues to function until the operator disengages the float activation device  86 . 
   In the second embodiment  82 , the controller  44  only initially compares the target pressure with the pressure sensor  84  readings indicating float circuit  72  pressure, commanding the float valve  74  to add or subtract hydraulic fluid from the float circuit  72  until the reading from the pressure sensor  84  matches the target pressure. Once charged to the target pressure, the float circuit  72  is sealed and the accumulator  90  acts to maintain target pressure in the float circuit  72  as the float cylinders  70  reciprocate over changing terrain. To change header float response while operating in header float mode, the operator may further manipulate the float setting device  88  without disengaging the float system. The controller  44  continuously monitors the float setting device  88  for changes, determining and applying new target pressures accordingly. The header float system continues to function until the operator disengages the float activation device  86 . 
     FIGS. 7 and 8  show schematics illustrating first and second embodiments,  92 ,  94  respectively, for a terrain following system used with the floating header  50 . Both systems serve to extend the terrain following capability of the floating header system  80 ,  82  by dynamically actuating the lift cylinders  24  in response to reciprocation of the float cylinders  70 . As the ground urges the header  50  up on inclines, shown in  FIG. 9B , the terrain following system  92 ,  94  causes the lift cylinders  24  to raise the header  50  upward such that the float cylinders  70  return to a nominal position, shown in  FIG. 9C . As gravity urges the header  50  down on declines, shown in  FIG. 9D , the terrain following system  92 ,  94  causes the lift cylinders  24  to lower the header  50  downward such that the float cylinders  70  again return to their nominal position, shown in  FIG. 9E . 
   The first embodiment  92  is a terrain following system used with the dynamic header float system  80 , while the second embodiment  94  is a terrain following system used with the resilient header float system  82 . In both embodiments, a position sensor  96  in communication with the controller  44 , in the form of a potentiometer, indicates relative reciprocation of each cylinder. In the illustrated embodiments, each position sensor  96  attaches to a corresponding lower link  66  and to the frame  52 . Within the cab  16 , operator input devices in communication with the controller  44  allow the operator to control the function of the terrain following system  92 ,  94 . Operator input devices include, but are not limited to, a lift command device  98  and a system activation device  100 . Examples of system activation devices  100  include toggle switches or push buttons. Examples of lift command devices  98  include levers or joystick controls. 
   During a harvesting operation with either embodiment  92 ,  94 , the operator manipulates the lift command device  98 , causing the controller  44  to command the lift cylinders  24  to lower the header  50  until the header  50  contacts the ground. The operator then engages the system activation device  100  to operate in a terrain following mode. Once engaged, the controller  44  continuously reads both position sensors  96 , calculates the average of the position sensor  96  readings, and then commands the lift valve  42  to add or subtract hydraulic fluid from the lift cylinders  24  until the average of the position sensor  96  readings indicate that the float cylinders  72  are at their nominal position. In this manner, the controller  44  continuously adjusts header  50  height over changing terrain, positioning the float header  50  for optimal function of the header float system  80 ,  82  as the combine  10  travels through the field. The terrain following system  92 ,  94  continues to function until the operator disengages the system activation device  100 , or until the operator manipulates the lift command device  98  to raise or lower the header  50 . 
   Having described the preferred embodiment, it will become apparent that various modifications can be made without departing from the scope of the invention as defined in the accompanying claims.