Abstract:
A suspension system for fixed-frame, towed agricultural implements having at least one floating head. A hydraulic cylinder is used for both lift and suspension of the floating head. A hydraulic accumulator provides expansion room for hydraulic fluid to move in and out of the hydraulic cylinder during suspension.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    U.S. patent application Ser. No. 11/927,866 filed Oct. 30, 2007 (Our Ref. 2-5169-110), is hereby incorporated by reference herein in its entirety. 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    Not applicable. 
       REFERENCE TO MICROFICHE APPENDIX 
       [0003]    Not applicable. 
       BACKGROUND OF THE INVENTION 
       [0004]    1. Field of the Invention 
         [0005]    The present invention relates generally to an agricultural implement, including a floating header. More particularly, the present invention relates to an improved suspension system for agricultural implements having one or more floating headers wherein the suspension hydraulic cylinders are also used to lift the header for transport. 
         [0006]    2. Background Art 
         [0007]    A three-point mounted mower with a suspension system is disclosed in U.S. patent application Ser. No. 5,417,042. Disclosed in this application is an example of a mower suspension system with separate elements having a first and a second chamber and separate fluid inlets. These pairs are intended for different functions. One pair is used to lift to a transport position while the other pair is used to transfer oil during operation to suspend the header. 
         [0008]    Another example of a three-point mounted mower is disclosed in U.S. Pat. No. 6,085,501. This patent describes a machine where the frame is not lifted to raise the header to a transport position, but where there are effectively two separate cylinders, one to lift into transport, another to suspend the header. The patent describes separate hydraulic rams. 
         [0009]    An example of a typical suspension for a trailed mower or mower conditioner is disclosed in U.S. patent application Ser. No. 6,055,800, wherein a cylinder lifts the frame and header to a transport position, while a spring provides a lift force to suspend the header in working position. 
         [0010]    The multiplicity of components for lifting and suspending a floating header on a fixed-frame agricultural implement increases complexity, cost, while decreasing reliability. 
         [0011]    There is, therefore, a need for a method and apparatus for both lifting and providing suspension for a floating header on a fixed-frame agricultural implement such as a mower. 
       BRIEF SUMMARY OF THE INVENTION 
       [0012]    An object of the present invention is to provide a suspension system for implements having a floating header. The suspension system shall permit the floating header to contact the ground with an appropriate pressure. Another object of this invention is to provide the suspension using the same hydraulic cylinders used to lift the floating header. 
         [0013]    In a first embodiment of the present invention, rams in the lift/flotation cylinders of the suspension system are in compression as they raise the header. In a second embodiment of this invention, the ram of the lift/flotation cylinder is in tension as it lifts the floating header. 
         [0014]    In both embodiments, a hydraulic accumulator is used to allow for changes in a hydraulic cylinders&#39; extension during operation without the usual valve manipulation to achieve those position changes. 
         [0015]    A take-up cylinder is incorporated with lift/flotation cylinders and the hydraulic accumulator to raise and lower the header. When the take-up cylinder is fully retracted, the hydraulic accumulator and the lift/flotation cylinders have reached their greatest pressures, and the lift/flotation cylinders their full extension so the header is fully raised. 
         [0016]    A valve is then opened slightly to allow the hydraulic accumulator to depressurize and the take-up cylinder to extend somewhat with the header under the force of gravity. When a predetermined pressure is achieved in the hydraulic accumulator, the valve is again closed. At this predetermined pressure, the header bears on the ground surface with the required force. 
         [0017]    In the second embodiment, a lift/flotation cylinder is connected to the hydraulic accumulator by its retract port, thereby raising a sub-frame by retraction. The process is the same as that given for the first embodiment. 
         [0018]    Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]      FIG. 1  is a perspective view of a towed agricultural mower having two hydraulic suspension cylinders mounted on the outer edges wherein the header is in a raised position; 
           [0020]      FIG. 2   a  is a first side elevation view of the agricultural mower with an accumulator also visible; 
           [0021]      FIG. 2   b  is a second side elevation view of the agricultural mower with the header in a lowered position; 
           [0022]      FIG. 3  is a schematic representation of the mower hydraulic system; 
           [0023]      FIG. 4  is an exploded view of the hydraulic circuit in the embodiment of  FIG. 1 ; 
           [0024]      FIG. 5   a  is an isometric view of a mower in a transport configuration in an alternative embodiment as used on a multi-frame mower having the main frame and sub-frame connected by a single, one-way suspension cylinder; 
           [0025]      FIG. 5   b  is a side elevation view of the rear of the mower in the alternative embodiment shown in  FIG. 5   a;    
           [0026]      FIG. 5   c  provides a visual layout of the hydraulic circuit in the alternative embodiment as in  FIG. 5   a ; and 
           [0027]      FIG. 5   d  is a schematic representation of the alternative embodiment of the mower hydraulic system. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0028]    The agricultural mower to which the present invention is applied is a towed, trailed, or drawn mower. This is in contrast to a tractor-mounted mower. Towed mowers have different suspension needs than do mounted mowers, as towed mowers are supported by the ground, independent of the tractor. 
         [0029]    Referring now to the drawings wherein like reference numerals correspond to the same or similar parts throughout the drawings, the present invention includes a system for suspending a header  6  from a fixed-frame agricultural mower using hydraulic cylinders  14  and an accumulator  40 . (A fixed-frame, for the purposes of this document, including the claims, is herein defined as a frame that does not articulate linearly relative to a ground-engaging wheel axle.) The header  6 , in turn, supports a cutter bar  9 . In a first embodiment, shown in  FIGS. 1-4 , a fixed-frame, towed mower  1  is equipped with two one-way hydraulic suspension cylinders  14  located at the outer edges of the frame  15  and supporting the header  6  via pivoting links  42 . The pitch control hydraulic cylinder  13  controls the orientation of the cutter bar  9  in relation to the ground, known as pitch, while the tongue swing cylinder  17  is used to control the orientation of the tongue  2  in relation to the frame  15 . 
         [0030]      FIG. 3  illustrates the hydraulic circuits, including the tongue circuit for controlling tongue swing cylinder  17 , with a first tractor remote valve, and the header circuit for controlling the pitch control cylinder  13  and hydraulic suspension cylinders  14  with a second tractor remote valve. The header circuit provides three functions including control of header tilt, flotation, and lift. The flotation is provided by a hydro-pneumatic accumulator  40  used to exchange volumes of hydraulic fluid with the lift/flotation cylinders. This function is necessary when the header  6  is lowered, to allow the header  6  to follow the terrain, which occurs in the first embodiment when the lift/flotation cylinders  14  are retracted, wherein they cooperate with the accumulator  40 . An upper pressurized gas chamber of the hydro-pneumatic accumulator  40  is under pressure. The pressure is shared with a lower chamber of the hydro-pneumatic accumulator  40 , open to the hydraulic system. 
         [0031]    The header circuit also includes a take-up cylinder  41  and a valve  39 . The take-up cylinder  41  controls the oil volume displaced for lifting and lowering the header. The valve  39  may be a manually operated ball valve that can be opened to allow flow, or closed to block flow. The valve  39  may alternatively be a solenoid operated valve capable of allowing flow when a solenoid is energized, and blocking flow then a solenoid is de-energized. The present invention is not limited to these types of valves. The functions of the valve  39  are described below. 
         [0032]    In operation the towed mower  1  is hydraulically connected to a tractor (not shown) which provides a source of oil and is used to pump oil into the mower hydraulic systems to perform a variety of functions including:
       1) to control the position of the mower  1  relative to the tractor, the cylinder  17 , as controlled by the first tractor remote valve  85  is extended or retracted, thereby changing the orientation of the tongue  2  relative to the frame  15 ;   2) to control the position of the header  6  relative to the ground, the second tractor remote valve  87  is moved to one extreme position which will cause the header  6  to lift, and when moved to the other extreme position will cause the header  6  to lower, and when left in the middle position will hold the header  6  in a set position;   3) charging the lift/flotation circuit.
 
Charging of the lift/flotation circuit is necessary in order to insure that the take-up cylinder  41 , a component of the mower hydraulic system, yet not strictly speaking a part of the suspension system, is properly filled with oil. The lift/flotation cylinders  14  and the tractor remote valve  87  can be directly connected or isolated by means of the valve  39 . In the first embodiment, as illustrated in  FIG. 4 , the valve  39  is set in a manifold at the base of the take-up cylinder  41 . Charging is completed by allowing oil to flow through the valve  39 , when opened, through the lines to the take-up cylinder  41 , while first allowing air to escape at the take-up cylinder, and then to fully extend that cylinder, while also purging air out of the lines between the valve  39  and the lift/flotation cylinders  14  and the pressure gage  60 . The tractor remote valve  87  is held in the position to force oil to the circuit until the lift/flotation cylinders  14  are in the extended position, and the header  6  is lifted to the transport position shown in  FIG. 2   a.  
       
 
         [0036]    After this first step of the charging procedure, the valve  39  is locked, isolating the lift/flotation cylinders  14  from direct connection to the tractor hydraulics. In the present embodiment for a fixed-frame mower  1  as in  FIGS. 1 ,  2   a  and  2   b , the accumulator  40  is biased so as to act like a compressive spring by plumbing it to the extend port of the lift/flotation cylinders  14 , most clearly shown in  FIGS. 3 and 4 . Thus, during this first step of the charging procedure, the tractor lifts the cutter bar  9  and pressurizes the accumulator  40 . To complete the charging procedure the tractor remote valve  87  is opened to the tractor hydraulic fluid reservoir so that it does not force oil through the remote valve  87 . This allows the oil to flow from the take-up cylinder  41  to the tractor hydraulic reservoir. Then the valve  39  is opened, either manually or electronically by the operator, to allow gravity to work against the accumulator  40  to lower the cutter bar  9  to the ground. The hydraulic system pressure can be viewed on a pressure gauge  60  so that the operator can bleed the valve  39  to allow the cutter bar  9  to press against the ground with appropriate pressure. This is done by pre-determining mower model-specific values for hydraulic system pressure at which the operator can close the valve  39  to maintain. The bias of the accumulator  40  to lift the cutter bar  9  keeps the cutter bar  9  from digging into the ground surface, yet is sufficiently small to allow gravity to press the cutter bar  9  against the surface and maintain continuous contact. This property of the cutter bar  9  is herein defined for the purposes of this document, including the claims, as “float.” 
         [0037]    Oil in the mower hydraulic system will constantly be seeking to occupy volume so as to obtain equilibrium pressures throughout the system. If the take-up cylinder valve  39  is locked, oil flow is restricted to flowing between the suspension cylinders  14  and the accumulator  40 . Thus, with the valve  39  locked, the cutter bar  9  cannot be lifted or lowered via the tractor hydraulic system but only by the exchange of oil between the cylinders  14  and accumulator  40  as would be caused by variations in the force the ground exerts on the cutter bar  9  due to ground surface irregularity while mowing. 
         [0038]    As the mower passes over uneven ground, the ground exerts changing forces on the cutter bar(s)  9 . The oil can flow between the cylinders  14  and the accumulator  40  to constantly maintain system pressure so that good contact between the cutter bar  9  and the ground is maintained. 
         [0039]    In the first embodiment for a fixed-frame mower, the suspension cylinders  14  are attached to a pivoting link  42  such that extending the cylinders  14  causes the header  6  to lift, while retracting the cylinder  14  lowers the header  6  to the ground. In an alternative embodiment, valuable to mowers which may have separate configurations for transport and mowing, a single one-way suspension cylinder  14  may be used as shown in  FIGS. 5   a - 5   d . This cylinder  14  could pivotally connect, for instance, to a main frame  15  and a rear sub-frame  62  where the main frame  15  is fixed and the rear sub-frame  62  is allowed to lift, lower, or roll about an axis parallel to a direction of travel. In  FIG. 5   a , the rear sub-frame  62  maintains its orientation to the ground by a four-bar linkage comprising an upper link set  12  and a lower link set  11 . The four-bar linkage is described more fully in U.S. patent application Ser. No. 11/927,866, filed Oct. 30, 2007, and is hereby incorporated by reference herein in its entirety. 
         [0040]    The rear sub-frame  62  is pivotally attached to a front sub-frame  10 , to which the header  6  is ultimately attached. The rear sub-frame  62  is a link within the four-bar linkage, and the orientation of the sub-frame  62  is dictated thereby. The front sub-frame  10  may be permitted to pivot relative to the rear sub-frame  62  in order to orient the header  6  in an appropriate position for operation or transport. 
         [0041]    Swing arm cylinders  65  are provided on both sides of the agricultural mower  1  to pivot the tool bars  9  relative to the front sub-frame  10 . 
         [0042]    In this second embodiment, the hydraulic system works by the same principles as in the first embodiment. However, the single cylinder  14  attached to the mower  1  as stated is configured to lift the sub-frame  10 ,  62  by retracting and to lower the sub-frame  10 ,  62  by extending. In this embodiment the accumulator  40  is plumbed to the retract port of the cylinder  14 , as clearly illustrated in  FIGS. 5   c  and  5   d.    
       Operational Process (Either Embodiment) 
       [0000]    
       
         
           
             1) Open the take-up valve  39 . 
             2) Using the tractor as the power source, pressurize the mower hydraulic system. The sub-frame/header  6  will rise to a maximum height due to full retraction of the take-up cylinder  41  and to fully stroking the cylinders  14 . 
             3) Close the take-up valve  39 . 
             4) Put the tractor in float. 
             5) Crack the valve  39  slowly to bleed excess pressure until the appropriate pressure is read from the gauge. The appropriate pressure will be established for each individual towed mower  1  model on which the present invention is incorporated. 
             6) Lock the valve  39  at an appropriate pressure. The cutter bars  9  will contact the ground with the hydraulic suspension of the present invention giving it the appropriate amount of contact pressure. The mower  1  is operational. 
           
         
       
     
         [0049]    As an alternative to step 2, using the tractor as the power source . . . , the pressure to the mower hydraulic system may be provided from the gas side of the accumulator  40 . Pressurized air, nitrogen, carbon dioxide, argon, helium, or any other appropriate gas may be used to effect this pressurization. 
         [0050]    The embodiments of the novel suspension system herein described may be utilized for any implement making use of a floating header. The invention is not intended to be limited to agricultural mowers. 
         [0051]    The above embodiments are the preferred embodiments, but this invention is not limited thereto. It is, therefore, apparent that many modifications and variations of the present invention are possible in light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.