Patent Description:
Some agricultural machines are configured to receive or connect to a cutter head for cutting standing crop material. Such agricultural machines may be referred to as self-propelled windrowers, and may often be configured to operate with several different styles and/or sizes of cutter heads. Each different size and/or style of cutter head may have different recommended operating settings for a header linkage system connecting the cutter head to the agricultural machine.

The agricultural machine and the attached cutter head may be configured to cut different crop materials. The crop materials include forages and grains. Because the crop materials have different characteristics, the header linkage system and cutter head may have to be positioned differently for different crop materials, or different cutter heads may have to be used for different crop materials.

Two commonly used styles of cutter heads include rotary style cutter heads which are often used for cutting forage crops, and draper style cutter heads which are often used for cutting grain crops. Each of the rotary style cutter heads and the draper style cutter heads may additionally come in different sizes. Both the rotary style cutter heads and the draper style cutter heads may be operated in either a fixed height operating condition, in which a position of the header linkage system is fixed relative to the frame of the agricultural machine so that the cutter head maintains a fixed height above the ground surface, or a float operating condition in which the header linkage system is allowed to move vertically relative to the frame to track the ground surface as the agricultural machine travels across the ground surface. <CIT> discloses a float arm load compensation system for a header of an agricultural harvester including a header frame.

When operating in the float operating condition, it is desirable for the header linkage system to exhibit different operating characteristics for the different style of cutter heads, i.e., the rotary style cutter head and the draper style cutter head. For example, because the rotary style cutter heads may be moved more quickly across the ground surface compared to the draper style cutter heads, it is often desirable for the header linkage system to be configured to exhibit a quick floatation response to quickly move the cutter head downward to maintain contact with the ground surface. In contrast, because the draper style cutter heads use a sickle cutter-bar, they are moved more slowly across the ground surface than the rotary style cutter heads and are more sensitive to plugging with mud. Accordingly, it is often desirable for the header linkage system to be configured to exhibit a slow floatation response to move the draper style cutter heads downward at a more controlled rate so that the sickle cutter-bar does not dig into the ground surface.

An agricultural machine according to claim <NUM> is provided. Preferred embodiments of the invention are provided in the dependent claims.

Accordingly, the agricultural machine described above enables the header linkage system to operate in a float operating condition with variable levels of downforce control for different styles of cutter heads and/or different operating conditions. By opening the downforce control valve, the piston side volume is open to tank and the downforce accumulator provides little to no resistance and the header linkage system will provide a slower return to ground contact. By closing the downforce control valve, the downforce accumulator acts as a spring to provide a quick return force to move the header linkage system quickly back into ground contact.

Referring to the Figures, wherein like numerals indicate like parts throughout the several views, an agricultural machine is generally shown at <NUM> in <FIG>. The example embodiment of the agricultural machine <NUM> shown in <FIG> includes, but is not limited to, a self-propelled windrower. However, it should be appreciated that the teachings of this disclosure may be applied to machines other than the example windrower depicted in the Figures.

Referring to <FIG>, the agricultural machine <NUM> includes a frame <NUM>, which supports a prime mover <NUM>. The prime mover <NUM> may include, but is not limited to, an internal combustion engine, an electric motor, a combination of both, or some other device capable of generating torque to power the agricultural machine <NUM>. A left front drive wheel <NUM> and a right front drive wheel <NUM> are each mounted to the frame <NUM>, adjacent a forward end of the frame <NUM>. The left front drive wheel <NUM> and the right front drive wheel <NUM> are rotatable about a transverse axis <NUM>. The transverse axis <NUM> is generally perpendicular to a longitudinal axis <NUM> of the frame <NUM>.

As understood by those skilled in the art, the left front drive wheel <NUM> and the right front drive wheel <NUM> may be simultaneously rotated in the same rotational direction and at the same rotational speed about the transverse axis <NUM> to drive the agricultural machine <NUM> forward or rearward, depending upon the direction of rotation. Additionally, the left front drive wheel <NUM> and the right front drive wheel <NUM> may be rotated in the same rotational direction at different rotational speeds about the transverse axis <NUM>, or in opposite rotational directions at the same or different rotational speeds about the transverse axis <NUM>, in order to turn the agricultural machine <NUM>.

Referring to <FIG>, the agricultural machine <NUM> further includes a left rear caster wheel <NUM> and a right rear caster wheel (not shown) attached to the frame <NUM>. As used herein, the term "caster wheel" should be understood to include a wheel that is able to rotate a full three hundred sixty degrees (<NUM>°) about a respective generally vertical axis. As such, each of the left rear caster wheel <NUM> and the right rear caster wheel are rotatable a full three hundred sixty degrees (<NUM>°) about a respective generally vertical axis. The left rear caster wheel <NUM> and the right rear caster wheel may be attached to the frame <NUM> in a suitable manner. The specific manner in which the left rear caster wheel <NUM> and the right rear caster wheel are attached to the frame <NUM> is not pertinent to the teachings of this disclosure, are understood by those skilled in the art, and are therefore not described in detail herein.

Referring to <FIG>, the agricultural machine <NUM> includes a hydraulic system <NUM>. The hydraulic system <NUM> includes a pressure source <NUM> configured to supply a flow of pressurized fluid. The pressure source <NUM> may include, but is not limited to, a fluid pump that is drivenly coupled to the prime mover <NUM>. The pressure source <NUM> draws fluid from a tank <NUM>, and circulates the fluid through a fluid circuit <NUM>. The tank <NUM> receives the fluid from the hydraulic system <NUM>, stores the fluid, and supplies the fluid to the pressure source <NUM>, e.g., the fluid pump. Fluid flow and/or pressure may be used to operate various components of the agricultural machine <NUM>, as described in greater detail below.

Referring to <FIG>, the agricultural machine <NUM> includes a header linkage system <NUM> attached to the frame <NUM>. In the implementation shown in the Figures and described herein, the header linkage system <NUM> is attached to the frame <NUM> adjacent the forward end of the frame <NUM>. The header linkage system <NUM> is configured for attaching a selected cutter head <NUM> from a plurality of different cutter heads <NUM> to the frame <NUM>. The plurality of different cutter heads <NUM> may include a rotary cutter <NUM> such as shown in <FIG>, or a draper cutter <NUM> such as shown in <FIG>. It should be appreciated that the plurality of different cutter heads <NUM> may further include different sizes of each of the rotary cutter <NUM> and the draper cutter <NUM>.

The fluid circuit <NUM> is configured for operating the header linkage system <NUM> in a float operating condition and a fixed height operating condition. When the fluid circuit <NUM> is configured to operate the header linkage system <NUM> in the float operating condition, the header linkage system <NUM> is allowed to move vertically relative to the frame <NUM>, as the agricultural machine <NUM> moves across a ground surface, so that the cutter head may track or follow the vertical undulations and changes in the ground surface.

Referring to <FIG> and <FIG>, the header linkage system <NUM> includes a rockshaft <NUM> rotatably mounted to the frame <NUM> for rotational movement about a shaft axis <NUM> that extends transverse to the longitudinal axis <NUM> of the frame <NUM>. A lift cylinder <NUM> is attached to and interconnects the rockshaft <NUM> and the frame <NUM>. The lift cylinder <NUM> is operable to rotate the rockshaft <NUM> about the shaft axis <NUM> in order to raise and lower the selected cutter head 46er relative to the ground surface. As such, the lift cylinder <NUM> is operated to control a vertical height of the selected cutter head <NUM> above the ground surface. In the example implementation described herein, the lift cylinder <NUM> is a single acting hydraulic cylinder in fluid communication with the hydraulic system <NUM>. A lift control valve <NUM> controls fluid communication between the lift cylinder <NUM> and the pressure source <NUM>. In other embodiments, the lift cylinder <NUM> may include a double acting hydraulic cylinder, an electrically actuated linear actuator, or some other device capable of extending and retracting. The lift cylinder <NUM> extends in response to fluid pressure and/or flow from the hydraulic system <NUM> in the usual manner, and is retracted by gravitational forces acting on the header linkage system <NUM> and/or the selected cutter head <NUM> attached to the header linkage system <NUM> as understood by those skilled in the art.

The header linkage system <NUM> may further include a tilt cylinder <NUM>. The tilt cylinder <NUM> is attached to and interconnects the frame <NUM> and the selected cutter head <NUM> attached to the header linkage system <NUM>. The tilt cylinder <NUM> is operable to rotate the selected cutter head <NUM> attached to the header linkage system <NUM> relative the ground surface. More specifically, the tilt cylinder <NUM> rotates the selected cutter head <NUM> about a tilt axis <NUM>, which extends transverse to the longitudinal axis <NUM> of the frame <NUM> and through distal ends of a left connecting arm <NUM> and a right connecting arm <NUM>. In the example implementation described herein, the tilt cylinder <NUM> is a double acting hydraulic cylinder in fluid communication with the hydraulic system <NUM>. In other embodiments, the tilt cylinder <NUM> may include a single acting hydraulic cylinder, an electrically actuated linear actuator, or some other device capable of extending and retracting. The tilt cylinder <NUM> extends and retracts in response to fluid pressure and/or flow from the hydraulic system <NUM> in the usual manner as understood by those skilled in the art.

The header linkage system <NUM> includes the left connecting arm <NUM> and the right connecting arm <NUM> noted above. The left connecting arm <NUM> is rotatably attached to the frame <NUM> below the rockshaft <NUM>, on a left side of the frame <NUM>. A left linkage <NUM> is attached to and interconnects the left connecting arm <NUM> and the rockshaft <NUM>. A left float cylinder <NUM> is attached to and interconnects the frame <NUM> and the left linkage <NUM>. A respective forward end of the left float cylinder <NUM> is attached to the left linkage <NUM>. The left float cylinder <NUM> extends rearward and vertically upward to a respective rearward end of the left float cylinder <NUM>, which is attached to the frame <NUM>.

The right connecting arm <NUM> is rotatably attached to the frame <NUM> below the rockshaft <NUM>, on a right side of the frame <NUM>. A right linkage <NUM> is attached to and interconnects the right connecting arm <NUM> and the rockshaft <NUM>. A right float cylinder <NUM> is attached to and interconnects the frame <NUM> and the right linkage <NUM>. A respective forward end of the right float cylinder <NUM> is attached to the right linkage <NUM>. The right float cylinder <NUM> extends rearward and vertically upward to a respective rearward end of the right float cylinder <NUM>, which is attached to the frame <NUM>.

In the example implementation shown in the Figures and described herein, the left float cylinder <NUM> is a double acting hydraulic cylinder. As is understood by those skilled in the art, the left float cylinder <NUM> includes a case defining an interior volume. A piston is disposed within the interior volume of the case. A rod is attached to the piston within the interior volume of the case and extends to a distal end positioned outside the case. The piston and the rod are slideably moveable within the interior space and relative to the case to change a length of the left float cylinder <NUM>. The left float cylinder <NUM> includes a rod side fluid port <NUM> and a piston side fluid port <NUM>. The rod side fluid port <NUM> of the left float cylinder <NUM> is in fluid communication with the pressure source <NUM> and may receive fluid from the pressure source <NUM> to retract the left float cylinder <NUM>. The piston side fluid port <NUM> of the left float cylinder <NUM> is in fluid communication with the pressure source <NUM> and may receive fluid from the pressure source <NUM> to extend the left float cylinder <NUM>.

A left float control valve <NUM> is in fluid communication with and interconnects the pressure source <NUM> and the rod side fluid port <NUM> of the left float cylinder <NUM>. The left float control valve <NUM> is fluidically positioned between the left float cylinder <NUM> and the pressure source <NUM>. The left float control valve <NUM> is selectively controllable between an open position and a closed position. When the left float control is disposed in the open position, the left float control valve <NUM> allows fluid communication between the pressure source <NUM> and the rod side fluid port <NUM> of the left float cylinder <NUM>. The fluid circuit <NUM> may be controlled so that the left float cylinder <NUM> is operable to retract in response to receiving fluid into the rod side fluid port <NUM> of the left float cylinder <NUM> via the left float control valve <NUM>. Additionally, when the left float control valve <NUM> is disposed in the open position, the fluid circuit <NUM> may be controlled to allow fluid communication between the rod side fluid port <NUM> of the left float cylinder <NUM> and the tank <NUM>. When the left float control valve <NUM> is disposed in the closed position, the left float control valve <NUM> blocks or prevents fluid communication or flow between the pressure source <NUM> and the rod side fluid port <NUM> of the left float cylinder <NUM>.

A left rod side accumulator <NUM> is in fluid communication with the rod side fluid port <NUM> of the left float cylinder <NUM>. The left rod side accumulator <NUM> is fluidically positioned within the fluid circuit <NUM> in fluid communication with and/or between the rod side fluid port <NUM> of the left float cylinder <NUM> and the left float control valve <NUM>. As understood by those skilled in the art and as used herein, an accumulator is a pressure vessel that holds a hydraulic fluid and a compressible gas separated by a flexible membrane or piston. The compressible gas is pre-charged to a pre-defined pressure. Hydraulic fluid introduced into the accumulator compresses the compressible gas until the pressure of the compressible gas matches that of the hydraulic fluid. The hydraulic fluid may be forced out of the accumulator by the compressible gas when the pressure of the hydraulic fluid drops below the pressure of the compressible gas. Accumulators may be used, for example, as energy storage devices and/or spring devices in the fluid circuit <NUM>.

The left float cylinder <NUM> is in fluid communication with the left rod side accumulator <NUM>. The left rod side accumulator <NUM> defines a left rod side volume <NUM> that is compressible in response to a fluid pressure above a defined left rod side set point. Fluid pressure within the left rod side volume <NUM> defined by the left rod side accumulator <NUM> may be controlled to provide a resistance against extension of the left float cylinder <NUM>, as well as provide dampening or provide a spring affect or spring rate against extension of the left float cylinder <NUM>. A left rod side pressure sensor <NUM> may be included to sense and monitor the fluid pressure applied to the rod side fluid port <NUM> of the left float cylinder <NUM> and the left rod side accumulator <NUM>.

In the example implementation shown in the Figures and described herein, the right float cylinder <NUM> is a double acting hydraulic cylinder. As is understood by those skilled in the art, the right float cylinder <NUM> includes a case defining an interior volume. A piston is disposed within the interior volume of the case. A rod is attached to the piston within the interior volume of the case and extends to a distal end positioned outside the case. The piston and the rod are slideably moveable within the interior space and relative to the case. The right float cylinder <NUM> includes a rod side fluid port <NUM> and a piston side fluid port <NUM>. The rod side fluid port <NUM> of the right float cylinder <NUM> is in fluid communication with the pressure source <NUM> and may receive fluid from the pressure source <NUM> to retract the right float cylinder <NUM>. The piston side fluid port <NUM> of the right float cylinder <NUM> is in fluid communication with the pressure source <NUM> and may receive fluid from the pressure source <NUM> to extend the right float cylinder <NUM>.

A right float control valve <NUM> is in fluid communication with and interconnects the pressure source <NUM> and the rod side fluid port <NUM> of the right float cylinder <NUM>. The right float control valve <NUM> is fluidically positioned between the right float cylinder <NUM> and the pressure source <NUM>. The right float control valve <NUM> is selectively controllable between an open position and a closed position. When the right float control valve <NUM> is disposed in the open position, the right float control valve <NUM> allows fluid communication between the pressure source <NUM> and the rod side fluid port <NUM> of the right float cylinder <NUM>. The fluid circuit <NUM> may be controlled so that the right float cylinder <NUM> is operable to retract in response to receiving fluid into the rod side fluid port <NUM> via the right float control valve <NUM>. Additionally, when the right float control valve <NUM> is disposed in the open position, the fluid circuit <NUM> may be controlled to allow fluid communication between the rod side fluid port <NUM> of the right float cylinder <NUM> and the tank <NUM>. When the right float control valve <NUM> is disposed in the closed position, the right float control valve <NUM> blocks or prevents fluid communication between the pressure source <NUM> and the rod side fluid port <NUM> of the right float cylinder <NUM>.

A right rod side accumulator <NUM> is in fluid communication with the rod side fluid port <NUM> of the right float cylinder <NUM>. The right rod side accumulator <NUM> is fluidically positioned within the fluid circuit <NUM> in fluid communication with and/or between the rod side fluid port <NUM> of the right float cylinder <NUM> and the right float control valve <NUM>. The right rod side accumulator <NUM> defines right rod side volume <NUM> that is compressible in response to a fluid pressure above a defined right rod side set point. Fluid pressure within the right rod side volume <NUM> defined by the right rod side accumulator <NUM> may be controlled to provide a resistance against extension of the right float cylinder <NUM>, as well as a provide dampening or provide a spring affect or spring rate against extension of the right float cylinder <NUM>. A right rod side pressure sensor <NUM> may be included to sense and monitor the fluid pressure applied to the rod side fluid port <NUM> of the right float cylinder <NUM> and the right rod side accumulator <NUM>.

A downforce accumulator <NUM> is in fluid communication with the piston side fluid port <NUM> of the left float cylinder <NUM> and the piston side fluid port <NUM> of the right float cylinder <NUM>. A piston side pressure sensor <NUM> may be included to sense and monitor the fluid pressure applied to the piston side fluid port <NUM> of the left float cylinder <NUM>, the piston side fluid port <NUM> of the right float cylinder <NUM>, and the downforce accumulator <NUM>.

A downforce control valve <NUM> is in fluid communication with the pressure source <NUM> and the downforce accumulator <NUM>. The downforce control valve <NUM> is fluidically positioned between the pressure source <NUM> on one side of the downforce control valve <NUM>, and the downforce accumulator <NUM>, the left float cylinder <NUM>, and the right float cylinder <NUM> on the other side of the downforce control valve <NUM>. The downforce control valve <NUM> is selectively controllable between an open position and a closed position.

When the downforce control valve <NUM> is disposed in the open position, the downforce control valve <NUM> allows fluid communication between the pressure source <NUM> and the piston side fluid port <NUM> of the right float cylinder <NUM> and the piston side fluid port <NUM> of the left float cylinder <NUM>. The fluid circuit <NUM> may be controlled so that the left float cylinder <NUM> and the right float cylinder <NUM> are operable to extend in response to receiving fluid into the piston side fluid port <NUM> of the right float cylinder <NUM> and the piston side fluid port <NUM> of the left float cylinder <NUM> via the downforce control valve <NUM>. Additionally, when the downforce control valve <NUM> is disposed in the open position, the fluid circuit <NUM> may be controlled to allow fluid communication between the piston side fluid port <NUM> of the right float cylinder <NUM>, the piston side fluid port <NUM> of the left float cylinder <NUM>, and the tank <NUM>. When the downforce control valve <NUM> is disposed in the closed position, the downforce control valve <NUM> blocks or prevents fluid communication or flow between the pressure source <NUM> and the piston side fluid port <NUM> of the right float cylinder <NUM> as well as the piston side fluid port <NUM> of the left float cylinder <NUM>.

The downforce accumulator <NUM> defines a piston side volume <NUM> that is compressible in response to a fluid pressure above a defined piston side set point. Fluid pressure within the piston side volume <NUM> of the downforce accumulator <NUM> may be controlled to provide a resistance against retraction of the right float cylinder <NUM> and the left float cylinder <NUM>, as well as a dampening or spring affect against retraction of the right float cylinder <NUM> and the left float cylinder <NUM>.

In the implementation described herein, the piston side set point of the piston side volume <NUM> is different than the left rod side set point of the left rod side accumulator <NUM> or the right rod side set point of the right rod side accumulator <NUM>. The piston side set point, the left rod side set point, and the right rod side set point may be calibrated to provide the desired operating characteristics of the specific cutter head <NUM> used and current field conditions.

When the downforce control valve <NUM> is disposed in the open position, the fluid circuit <NUM> may be controlled to operate the header linkage system <NUM> in a first float condition. When the header linkage system <NUM> is operated in the first float condition, the downforce accumulator <NUM> exhibits a first pressure and the header linkage system <NUM> exhibits a first header float return speed in response to the first pressure from the downforce accumulator <NUM>. When the downforce control valve <NUM> is disposed in the closed position, the fluid circuit <NUM> may be controlled to operate the header linkage system <NUM> in a second float condition. When the header linkage system <NUM> is operated in the second float condition, the downforce accumulator <NUM> exhibits a second pressure and the header linkage system <NUM> exhibits a second header float return speed in response to the second pressure from the downforce accumulator <NUM>. In the implementation described herein, the first pressure of the downforce accumulator <NUM> and the first header float return speed are less than the second pressure of the downforce accumulator <NUM> and the second header float return speed.

The fluid circuit <NUM> further includes a system return line <NUM>. The system return line <NUM> interconnects an output <NUM> of the pressure source <NUM> and the tank <NUM> in fluid communication. A return valve <NUM> is in fluid communication with the system return line <NUM>. The return valve <NUM> is fluidically positioned between the pressure source <NUM> and the tank <NUM>, within the system return line <NUM>. The return valve <NUM> is selectively controllable between an open position and a closed position. When the return valve <NUM> is disposed in the open position, the return valve <NUM> allows fluid communication or flow through the system return line <NUM> to the tank <NUM>. When the return valve <NUM> is disposed in the closed position, the return valve <NUM> blocks or prevents fluid communication or flow through the system return line <NUM> to the tank <NUM>.

The fluid circuit <NUM> may further include a pressure bypass line <NUM> including a pressure bypass valve <NUM>. The pressure bypass line <NUM> and the pressure bypass valve <NUM> are in fluid communication with and fluidically disposed between the output <NUM> of the pressure source <NUM> and the tank <NUM>. In response to fluid pressure within the fluid circuit <NUM> exceeding a defined maximum, the pressure bypass valve <NUM> may open to connect the output <NUM> of the pressure source <NUM> with the tank <NUM>.

The agricultural machine <NUM> further includes an operator station <NUM>, which houses control components of the agricultural machine <NUM>. The control components may include, but are not limited to, an output and an input. The output is operable to convey a message to an operator. The input is operable to receive instructions from the operator. In the example implementation described herein, the input and the output are combined and implemented as a touch screen display <NUM>. Messages may be communicated to the operator through the touch screen display <NUM>, and data may be entered by the operator by touching the touch screen display <NUM> as is understood by those skilled in the art. It should be appreciated that the input and the output may differ from the example implementation described herein and may be separate or combined components. For example, the output may include, but is not limited to, a video only display, an audio speaker, a light board, etc. The input may include, but is not limited to, a mouse, a keyboard, a microphone, etc..

A header controller <NUM> is disposed in communication with the touch screen display <NUM>, the tilt control valve, the lift control valve <NUM>, the left float control valve <NUM>, the left rod side pressure sensor <NUM>, the right float control valve <NUM>, the right rod side pressure sensor <NUM>, the downforce control valve <NUM>, and the piston side pressure sensor <NUM>. The header controller <NUM> is operable to receive data entry from the, left rod side pressure sensor <NUM>, the right rod side pressure sensor <NUM>, the piston side pressure sensor <NUM>, as well as the touch screen display <NUM>. The header controller <NUM> may additionally send messages through the touch screen display <NUM>, and control the operation of the tilt cylinder <NUM>, the lift control valve <NUM>, the left float control valve <NUM>, the right float control valve <NUM>, and the downforce control valve <NUM>. While the header controller <NUM> is generally described herein as a singular device, it should be appreciated that the header controller <NUM> may include multiple devices linked together to share and/or communicate information therebetween. Furthermore, it should be appreciated that all or parts of the header controller <NUM> may be located on the agricultural machine <NUM> or located remotely from the agricultural machine <NUM>.

The header controller <NUM> may alternatively be referred to as a computing device, a computer, a controller, a control unit, a control module, a module, etc. The header controller <NUM> includes a processor <NUM>, a memory <NUM>, and all software, hardware, algorithms, connections, sensors, etc., necessary to manage and control the operation of the touch screen display <NUM>, the tilt cylinder <NUM>, the lift control valve <NUM>, the left float control valve <NUM>, the right float control valve <NUM>, and the downforce control valve <NUM>. As such, a method may be embodied as a program or algorithm operable on the header controller <NUM>. It should be appreciated that the header controller <NUM> may include any device capable of analyzing data from various sensors, comparing data, making decisions, and executing the required tasks.

As used herein, "controller" is intended to be used consistent with how the term is used by a person of skill in the art, and refers to a computing component with processing, memory, and communication capabilities, which is utilized to execute instructions (i.e., stored on the memory or received via the communication capabilities) to control or communicate with one or more other components. In certain embodiments, the header controller <NUM> may be configured to receive input signals in various formats (e.g., hydraulic signals, voltage signals, current signals, CAN messages, optical signals, radio signals), and to output command or communication signals in various formats (e.g., hydraulic signals, voltage signals, current signals, CAN messages, optical signals, radio signals).

The header controller <NUM> may be in communication with other components on the agricultural machine <NUM>, such as hydraulic components, electrical components, and operator inputs within the operator station <NUM>. The header controller <NUM> may be electrically connected to these other components by a wiring harness such that messages, commands, and electrical power may be transmitted between the header controller <NUM> and the other components. Although the header controller <NUM> is referenced in the singular, in alternative embodiments the configuration and functionality described herein can be split across multiple devices using techniques known to a person of ordinary skill in the art.

The header controller <NUM> may be embodied as one or multiple digital computers or host machines each having one or more processors, read only memory (ROM), random access memory (RAM), electrically-programmable read only memory (EPROM), optical drives, magnetic drives, etc., a high-speed clock, analog-to-digital (A/D) circuitry, digital-to-analog (D/A) circuitry, and any required input/output (I/O) circuitry, I/O devices, and communication interfaces, as well as signal conditioning and buffer electronics.

The computer-readable memory <NUM> may include any non-transitory/tangible medium which participates in providing data or computer-readable instructions. The memory <NUM> may be non-volatile or volatile. Non-volatile media may include, for example, optical or magnetic disks and other persistent memory. Example volatile media may include dynamic random access memory (DRAM), which may constitute a main memory. Other examples of embodiments for memory include a floppy, flexible disk, or hard disk, magnetic tape or other magnetic medium, a CD-ROM, DVD, and/or any other optical medium, as well as other possible memory devices such as flash memory.

The header controller <NUM> includes the tangible, non-transitory memory <NUM> on which are recorded computer-executable instructions, including a header attachment and control algorithm <NUM>. The processor <NUM> of the header controller <NUM> is configured for executing the header attachment and control algorithm <NUM>. The header attachment and control algorithm <NUM> implements a method of controlling the agricultural machine <NUM>.

The header controller <NUM> may control the header linkage system <NUM> for operation between the float operating condition and the fixed height operating condition. When the header linkage system <NUM> is configured for the fixed height operating condition, the position of the header linkage system <NUM> is fixed relative to the frame <NUM> of the agricultural machine <NUM>. When the header linkage system <NUM> is configured for the float operating condition, the header linkage system <NUM> allows the selected cutter head <NUM> to vertically track the ground surface during horizontal movement of the agricultural machine <NUM> over the ground surface.

The header controller <NUM> may receive commands from the operator via the touch screen display <NUM>. The commands may include, but are not limited to, a selection of the desired operating condition, i.e., the fixed height operating condition or the float operating condition. If the float operating condition is selected, the header controller <NUM> may further receive commands from the operator selecting a desired float condition, i.e., the first float condition or the second float condition. The header controller <NUM> may then control the return valve <NUM>, the downforce control valve <NUM>, the left float control valve <NUM> and/or the right float control valve <NUM> to configure the fluid circuit <NUM> for the selected float condition, i.e., the first float condition or the second float condition.

Referring to <FIG>, control of the fluid circuit <NUM> for controlling the header linkage system <NUM> in the first float condition is described. Prior to configuring the fluid circuit <NUM> as shown in <FIG>, the header controller <NUM> may control the return valve <NUM> into its closed position and the left float control valve <NUM> and the right float control valve <NUM> may be controlled into their respective open positions to pressurize the left rod side volume <NUM> and the right rod side volume <NUM> to a desired fluid pressure. Once the left rod side volume <NUM> and the right rod side volume <NUM> have reached their respective desired fluid pressures, the header controller <NUM> may control the left float control valve <NUM> and the right float control valve <NUM> into their respective closed positions. As shown in <FIG>, in order to operate the header linkage system <NUM> in the first float condition, the header controller <NUM> controls or maintains the left float control valve <NUM> and the right float control valve <NUM> in their respective closed positions, controls the downforce control valve <NUM> into its open position and controls the return valve <NUM> into its open position. This configuration opens fluid communication between the piston side fluid port <NUM> of the left float cylinder <NUM>, the piston side fluid port <NUM> of the right float cylinder <NUM> and the downforce accumulator <NUM>, with the tank <NUM> through the return valve <NUM>. When configured this way, the downforce accumulator <NUM> does not provide any significant damping and does not provide a significant spring affect to and/or does not significantly bias the header linkage system <NUM> downward. As such, the header linkage system <NUM> moves downward relative to the frame <NUM> at the first header float return speed, which is a slower return speed. The first header float return speed is based at least in part on the weight of the cutter head <NUM>, the fluid pressure within the left rod side volume <NUM> relative to the left rod side set point, and the fluid pressure within the right rod side volume <NUM> relative to the left rod side set point. The operator may select the first float condition when using the draper cutter <NUM>, which is moved more slowly across the ground surface than the rotary cutter <NUM>, thereby allowing more time to return the cutter head <NUM> to the ground surface. Additionally, the draper cutter <NUM> is more sensitive to contacting the ground surface. As such, it is desirable to control it more precisely and/or slowly to ensure that the draper cutter <NUM> does not contact the ground surface.

Referring to <FIG>, control of the fluid circuit <NUM> for controlling the header linkage system <NUM> in the second float condition is described. Prior to configuring the fluid circuit <NUM> as shown in <FIG>, the header controller <NUM> may control the return valve <NUM> into its closed position and the left float control valve <NUM> and the right float control valve <NUM> into their respective open positions to pressurize the left rod side volume <NUM> and the right rod side volume <NUM> to a desired fluid pressure. Once the left rod side volume <NUM> and the right rod side volume <NUM> have reached their respective desired fluid pressures, the header controller <NUM> may control the left float control valve <NUM> and the right float control valve <NUM> into their respective closed positions. Additionally, prior to configuring the fluid circuit <NUM> as shown in <FIG>, the header controller <NUM> may control the return valve <NUM> into its closed position and the downforce control valve <NUM> into its open position to pressurize the piston side volume <NUM> to a desired fluid pressure. Once the piston side volume <NUM> has reached its desired fluid pressure, the header controller <NUM> may control the downforce control valve <NUM> into its closed position. As shown in <FIG>, in order to operate the header linkage system <NUM> in the second float condition, the header controller <NUM> controls or maintains the left float control valve <NUM> and the right float control valve <NUM> in their respective closed positions. Additionally, the header controller <NUM> controls or maintains the downforce control valve <NUM> in its closed position and controls the return valve <NUM> into its open position. This configuration closes or blocks fluid communication between the piston side fluid port <NUM> of the left float cylinder <NUM>, the piston side fluid port <NUM> of the right float cylinder <NUM> and the downforce accumulator <NUM> with the tank <NUM>. Additionally, this configuration closes or blocks fluid communication between the left rod side fluid port <NUM> of the left float cylinder <NUM> and the left rod side volume <NUM> and the tank <NUM>, as well as the right rod side fluid port <NUM> of the right float cylinder <NUM> and the right rod side volume <NUM> and the tank <NUM>.

When configured this way, the downforce accumulator <NUM> provides a significant damping affect and provides a significant spring affect to and/or biases the header linkage system <NUM> downward. As such, the header linkage system <NUM> moves downward at the second header float return speed, which is a faster return speed based at least in part on the fluid pressure within the piston side volume <NUM> relative to the piston side set point in addition to the weight of the cutter head <NUM>, the fluid pressure within the left rod side volume <NUM> relative to the left rod side set point, the fluid pressure within the right rod side volume <NUM> relative to the left rod side set point, and the fluid pressure within the piston side volume <NUM> relative to the piston side set point. As such, the stored energy in the downforce accumulator <NUM> pushes or biases the cutter head <NUM> and the header linkage system <NUM> downward to increase the speed at which the cutter head <NUM> returns to ground contact. The operator may select the second float condition when using the rotary cutter <NUM>, which is moved more quickly across the ground surface than the draper cutter <NUM>, thereby requiring a quicker return response time, and because the rotary cutter <NUM> is less sensitive to contacting the ground surface.

Referring to <FIG>, an alternative embodiment of the hydraulic system is generally shown in at <NUM>. Reference numerals used to identify features in <FIG> are used to identify identical features in <FIG>. The hydraulic system <NUM> shown in <FIG> eliminates the lift cylinder <NUM> and the lift control valve <NUM> shown in <FIG>. Additionally, the hydraulic system <NUM> shown in <FIG> includes a left lift control valve <NUM> and a right lift control valve <NUM>.

The left lift control valve <NUM> is fluidically positioned between the left float control valve <NUM> and the left rod side accumulator <NUM> in a position that does not interrupt or interfere with fluid communication between the left float control valve <NUM> and the rod side fluid port <NUM> of the left float cylinder <NUM>. The left lift control valve <NUM> controls fluid communication between the left rod side accumulator <NUM> and the rod side fluid port <NUM> of the left float cylinder <NUM>. The left lift control vale <NUM> is moveable between an open position allowing fluid communication between the left rod side accumulator <NUM> and the rod side fluid port <NUM> of the left float cylinder <NUM>, and a closed position blocking fluid communication between the left rod side accumulator <NUM> and the rod side fluid port <NUM> of the left float cylinder <NUM>. When the left lift control valve <NUM> is disposed in its open position, thereby allowing fluid communication between the left rod side accumulator <NUM> and the rod side fluid port <NUM> of the left float cylinder <NUM>, the left float cylinder <NUM> and the hydraulic system <NUM> may be controlled to operate in either the first float condition or the second float condition as described above with reference to <FIG> and <FIG>. When the left lift control valve <NUM> is disposed in its closed position, thereby blocking fluid communication between the left rod side accumulator <NUM> and the rod side fluid port <NUM> of the left float cylinder <NUM>, the left float cylinder <NUM> and the hydraulic system <NUM> may be controlled to raise or lower the header linkage system <NUM>, thereby providing lift functionally to the header linkage system <NUM>.

The right lift control valve <NUM> is fluidically positioned between the right float control valve <NUM> and the right rod side accumulator <NUM> in a position that does not interrupt or interfere with fluid communication between the right float control valve <NUM> and the rod side fluid port <NUM> of the right float cylinder <NUM>. The right lift control valve <NUM> controls fluid communication between the right rod side accumulator <NUM> and the rod side fluid port <NUM> of the right float cylinder <NUM>. The right lift control valve <NUM> is moveable between an open position allowing fluid communication between the right rod side accumulator <NUM> and the rod side fluid port <NUM> of the right float cylinder <NUM>, and a closed position blocking fluid communication between the right rod side accumulator <NUM> and the rod side fluid port <NUM> of the right float cylinder <NUM>. When the right lift control valve <NUM> is disposed in its open position, thereby allowing fluid communication between the right rod side accumulator <NUM> and the rod side fluid port <NUM> of the right float cylinder <NUM>, the right float cylinder <NUM> and the hydraulic system <NUM> may be controlled to operate in either the first float condition or the second float condition as described above with reference to <FIG> and <FIG>. When the right lift control valve <NUM> is disposed in its closed position, thereby blocking fluid communication between the right rod side accumulator <NUM> and the rod side fluid port <NUM> of the right float cylinder <NUM>, the right float cylinder <NUM> and the hydraulic system <NUM> may be controlled to raise or lower the header linkage system <NUM>, thereby providing lift functionally to the header linkage system <NUM>.

Accordingly, in the implementation shown in <FIG>, the left float cylinder <NUM> and the right float cylinder <NUM> may provide both the float functionality as well as the lift functionally performed by the lift cylinder <NUM> and the lift control valve <NUM> shown in <FIG>.

Claim 1:
An agricultural machine (<NUM>) comprising:
a frame (<NUM>);
a header linkage system (<NUM>) attached to the frame (<NUM>) and configured for attaching a cutter head (<NUM>) to the frame (<NUM>);
a tank (<NUM>) operable to store a supply of a fluid;
a pressure source (<NUM>) in fluid communication with the tank (<NUM>) and operable to receive fluid from the tank (<NUM>) and circulate the fluid through a fluid circuit (<NUM>);
a float cylinder (<NUM>, <NUM>) interconnecting the header linkage system (<NUM>) and the frame (<NUM>), the float cylinder (<NUM>, <NUM>) including a rod side fluid port (<NUM>, <NUM>) in fluid communication with the pressure source (<NUM>) for receiving fluid from the pressure source (<NUM>) to retract the float cylinder (<NUM>, <NUM>), and a piston side fluid port (<NUM>, <NUM>);
a downforce accumulator (<NUM>) in fluid communication with the piston side fluid port (<NUM>, <NUM>) of the float cylinder (<NUM>, <NUM>); and
a downforce control valve (<NUM>) in fluid communication with the pressure source (<NUM>) and the downforce accumulator (<NUM>), wherein the downforce control valve (<NUM>) is selectively controllable between an open position allowing fluid communication between the pressure source (<NUM>) and the downforce accumulator (<NUM>), and a closed position blocking fluid communication between the pressure source (<NUM>) and the downforce accumulator (<NUM>),
characterized in that
the agricultural machine (<NUM>) further comprising a header controller (<NUM>) configured to control the downforce control valve (<NUM>) to the open position to operate the header linkage system (<NUM>) in a first float condition exhibiting a first header float return speed, and control the downforce control valve (<NUM>) to the closed position to operate the header linkage system (<NUM>) in a second float condition exhibiting a second header float return speed, wherein the first header float return speed is less than the second header float return speed.