Patent Description:
In the hay and forage industry, agricultural windrowers are configured to cut crop material from the ground and arrange the cut material in windrows for later processing (e.g., by a separate baler). A windrower may include a header having a wide cutter assembly thereon that extends across a path of travel of the machine. The cutter assembly includes an arrangement of gear-driven, rotary cutters that function to cut the crop material, with one or more motors (e.g., hydraulic motors) driving the gears. The cut crop material is then provided to a conditioner assembly in the header, which may act to crimp the crop after it is cut and redirect the crimped crop to form it into a uniform windrow. <CIT>, <CIT> and <CIT> disclose a mower or a cutterbar assembly with a series of rotary cutters that are driven through a drive train. The drive train is driven through a first and a second gear, the first and the second gear being driven by a separate motor.

To overcome the drawbacks of the prior art, the present invention provides a work vehicle with the features of claim <NUM>.

A The work vehicle includes a header supported by a chassis of the vehicle, with the header including a cutter assembly. The cutter assembly includes, in turn, a cutter bar frame, a series of rotary cutters mounted on the cutter bar frame and arranged in a lengthwise direction, and a gear train having gears coupled to the series of rotary cutters to transfer power thereto. The gear train having a first gear and a second gear. The work vehicle also includes a cutter control system having a first motor coupled to the first gear of the gear train to provide power to the gear train, a second motor coupled to the second gear of the gear train to provide power to the gear train, and a controller, including a processor and memory architecture, operably connected to the first motor and the second motor to control operation thereof. The cutter control system is configured to drive the first gear at a first speed via the first motor and to drive the second gear at a second speed via the second motor, with the second speed being different than the first speed to pre-load the gear train into enmeshing engagement with each other in one rotational direction.

Furthermore, according to a second aspect of the present invention, a A- method of controlling a cutter assembly in a header of a work vehicle for cutting crops in accordance with claim <NUM> is further disclosed. The method includes providing a cutter assembly having a series of rotary cutters coupled to a gear train having a first gear and a second gear and providing a first motor and a second motor to drive the first gear and the second gear, respectively, with the first and second motors operated by a controller. The method also includes driving the first gear at a first speed with the first motor and driving the second gear at a second speed with the second motor, with the first speed being different than the second speed to pre-load the gear train into enmeshing engagement with other in one rotational direction.

The details of one or more embodiments are set-forth in the accompanying drawings and the description below. Other features and advantages will become apparent from the description, the drawings, and the claims.

At least one example of the present disclosure will hereinafter be described in conjunction with the following figures:.

For simplicity and clarity of illustration, descriptions and details of well-known features and techniques may be omitted to avoid unnecessarily obscuring the example and non-limiting embodiments of the invention described in the subsequent Detailed Description. It should further be understood that features or elements appearing in the accompanying figures are not necessarily drawn to scale unless otherwise stated.

Embodiments of the present disclosure are shown in the accompanying figures of the drawings described briefly above. Various modifications to the example embodiments may be contemplated by one of skill in the art without departing from the scope of the present invention, as set-forth the appended claims.

As previously noted, agricultural windrowers include a header having a wide cutter assembly thereon that extends across a path of travel of the machine, with one common style of cutter assembly including an arrangement of gear-driven, rotary cutters that function to cut the crop material. The rotary cutters extend generally along a length of the cutter assembly, with a gear train coupled to the rotary cutters to provide a driving power thereto. In many cutter bar assemblies, the gear train is driven by a single motor from one end of the cutter assembly, but some cutter bar assemblies have a dual motor configuration where the gear train is driven from both ends of the cutter assembly. In either configuration, the gears in the gear train are designed to have "clearance" or "gear backlash" between the gear teeth, which is necessary to prevent jamming and provide for smooth rotation of the meshed gears, while also may minimizing noise and preventing overheating of the gears. Because there is backlash provided between the gear teeth, a gear can be rotated a slight amount relative to its adjacent gear. When a series of gears are put together, as with the gear train of the cutter assembly, the amount of rotational movement of the last gear in the drive train relative to the first gear can be significant.

The above-described relative motion between the gears may cause issues when the windrower is operated. That is, when the windrower is cutting crop, one end of the cutter assembly can be loaded more heavily than the other end. In a single motor embodiment, if the end furthest from the motor is loaded less heavily than the end nearest to the motor, the gears on the far end can "over-run" or turn slightly faster than the motor because they have momentum. When this happens, the gear teeth are momentarily loaded in the reverse rotational direction, and a frequent reversal in the gear loading direction will result in gear "chatter" in the gear train. In a dual motor embodiment, crop loading on the gear train can similarly cause the motors on each of the opposing ends of the cutter assembly to be alternately loaded more heavily than the other motor. This causes the gears to be loaded up in one rotational direction when a gear driven by the first motor on one end of the cutter assembly is turning faster than a gear driven by the second motor on the other end of the cutter assembly and causes the gears to be loaded up in the other rotational direction when the gear driven by the second motor turns faster than the gear driven by the first motor. Again, when this happens, the gear teeth are alternately loaded in differing directions, resulting in gear chatter. Undesirably, this gear chatter in the cutter assembly can cause the gears to wear out sooner than desired.

To prevent the gear train from being alternately loaded up in differing directions during operation and reduce the likelihood of gear chatter, a work vehicle cutter assembly with a pre-loaded gear train and an associated control method are provided. Specifically, a cutter control system operates to drive a first gear of the gear train at a first speed and drive a second gear of the gear train at a different second speed to generate torque wind-up on the gears, which causes the gears to remain biased in one rotational direction during operation of the cutter assembly. This torque wind-up or pre-loading of the gears inhibits the gears from alternately being loaded in different rotational directions during operation of the cutter assembly, thereby reducing or eliminating gear chatter and reducing the wear on the gears associated therewith.

According to example embodiments, the cutter control system operates to control first and second motors that drive the first and second gears, respectively. The cutter control system operates the second motor at a speed that is slightly lower than the speed of the first motor and maintains the second motor at a lower speed during operation to pre-load the gears of the gear train in one rotational direction.

In certain embodiments, the cutter control system is a hydraulic circuit that provides hydraulic oil to a first hydraulic motor and a second hydraulic motor of the cutter assembly, to drive the respective hydraulic motors. The hydraulic circuit controls the amount of hydraulic oil provided to the first and/or second hydraulic motors to controllably operate the first motor at a first speed and the second motor at a second speed, where the first speed is higher than the second speed. The first motor thereby operates to apply a main driving force to one end of the gear train while the second motor operates to apply a braking force to the other end of the gear train, with a torque wind-up being generated in the gear train to pre-load the gears thereof into enmeshing engagement with each other in one rotational direction (i.e., directionally pre-load the gears). The hydraulic circuit can control the amount of hydraulic oil provided to the first and/or second hydraulic motors via any of a number of hydraulic circuit arrangements, including by use of: an orifice or orifice valve that restricts hydraulic fluid flow to an inlet of one of the hydraulic motors, variable displacement pumps that selectively control hydraulic fluid flow to the hydraulic motors, and/or a priority valve that increases hydraulic fluid flow to an inlet of one of the hydraulic motors, as nonlimiting examples.

In other implementations, the cutter control system is an electric control system where motor drives provide a controlled power to a first electric motor and a second electric motor of the cutter assembly, to drive the respective electric motors. The motor drives operate through associated power electronics to control the voltage and/or current applied to the electric motors to controllably operate the first motor at a first speed and the second motor at a second speed, where the first speed is higher than the second speed. The first motor thereby operates to apply a main driving force to one end of the gear train while the second motor operates to apply a braking force to the other end of the gear train, with a torque wind-up being generated in the gear train to pre-load the gears thereof into enmeshing engagement with each other.

Example embodiments of a work vehicle with a cutter assembly and associated cutter control system according to this disclosure will now be described in conjunction with <FIG>. By way of non-limiting examples, the following describes the cutter assembly and cutter control system as incorporated into a self-propelled windrower. The following examples notwithstanding, the cutter assembly and cutter control system can be incorporated into other types of work vehicles, mower assemblies, or machines that include an elongated gear train therein and that could benefit from protection against gear chatter in the gear train. It is therefore recognized that aspects of the invention are not meant to be limited only to the specific embodiments described hereafter.

With initial reference to <FIG>, a self-propelled windrower <NUM> is illustrated that is operable to mow and collect standing crop in a field, condition the cut crop as it moves through the machine (e.g., to improve its drying characteristics), and then return the conditioned material to the field in a windrow or swath. The windrower <NUM> includes a main chassis <NUM> supported on driven right and left front wheels 24R and <NUM>, respectively and on right and left caster mounted rear wheels, of which only a right rear wheel 26R is shown. Carried on a forward end region of the chassis <NUM> is a cab <NUM>. Mounted on the chassis <NUM> behind the cab <NUM> is a casing <NUM> within which is located a power source (not shown) such as an internal combustion engine. A harvesting header <NUM> is coupled so as to be supported by the forward end of the chassis <NUM>. Operator controls (not shown) are provided in the cab <NUM> for operation of the windrower <NUM>, including the attached harvesting header <NUM>.

The harvesting header <NUM> includes an outer housing <NUM>, a top portion of which is removed in <FIG> to illustrate various internal components of the header <NUM>. Positioned within housing <NUM> is a cutter assembly <NUM> that delivers cut crop to a following crop converging auger <NUM> that directs crop rearward into a discharge passage for further processing by a crop conditioning arrangement including upper and lower crop conditioning rolls <NUM> and <NUM>, respectively. Conditioned crop is expelled to the rear by the conditioning rolls <NUM> and <NUM> and is formed into a windrow by upright right and left, windrow forming panels (not shown) which are supported by a top wall of an open-bottomed frame <NUM> located between the front wheels 24R and <NUM>.

In certain embodiments, a controller <NUM> may also be provided. The controller <NUM> may be in electrical (or other) communication with various devices of the windrower <NUM>, to control various aspects of the operation of the windrower. In particular, the controller <NUM> may communicate with components in header <NUM> to control operation of cutter assembly <NUM>. The controller <NUM> may be configured as a computing device with one or more processors and memory architectures, as a hardwired computing circuit (or circuits), as a hydraulic or electrohydraulic control device, and so on.

As shown in greater detail in <FIG>, the cutter assembly <NUM> includes a cutter bar frame <NUM> that forms a base of the assembly <NUM>. Arranged along the cutter bar frame <NUM> is a series of rotary cutters <NUM> (e.g., ten cutters, as in <FIG>) that extend across the path of travel of the windrower <NUM>, with each cutter <NUM> being rotatable about its own upright axis. For the sake of convenience, the ten cutters <NUM> in <FIG> will be denoted by the letters (a)-(j), beginning with the left most cutter in the series as viewed from the front of the machine. The cutters <NUM> are rotatably supported on an elongated, flat gear case <NUM> that extends underneath the cutters <NUM> for the full length thereof, with the gear case <NUM> mounted to a top side of the cutter bar frame <NUM>. The gear case <NUM> includes openings or pockets <NUM> therein, as shown in <FIG>, and contains a train of flat spur gears - i.e., gear train <NUM> including gears <NUM> - a portion of which is shown in <FIG>. The gear train <NUM> extends the length of the cutter assembly <NUM>, with the gears <NUM> operably engaged with one another to distribute driving power between one another and to the cutters <NUM>(a)-<NUM>(j). Each of the cutters <NUM> includes a generally elliptical, formed blade carrier <NUM> and a pair of blades <NUM> mounted at opposite ends of the carrier <NUM>. As shown in <FIG>, all of the cutters <NUM> are ninety degrees out of phase with one another inasmuch as the circular paths of travel of the blades <NUM> of adjacent cutters <NUM> overlap one another and must be appropriately out of phase to avoid striking each other. Due to the positive mechanical drive connection between the group of rotary cutters <NUM> through the spur gears <NUM>, such cutters <NUM> always remain properly in phase with one another.

A shaft assembly <NUM> is coupled to each of the outermost rotary cutters <NUM>(a), <NUM>(j) on opposing ends of the cutter assembly <NUM> and that projects upwardly from the cutter to define the axis of rotation thereof, with the outermost gears <NUM> of the gear train <NUM> driven by the shaft assemblies <NUM> for rotation therewith, as shown in phantom in <FIG>. While shaft assemblies <NUM> are shown coupled to outermost rotary cutters <NUM>(a), <NUM>(j), it is recognized that the shaft assemblies <NUM> could be coupled to other rotary cutters, such as rotary cutters <NUM>(b), <NUM>(i), for example. Each shaft assembly <NUM> is centered within a cage <NUM> that provides protection thereto, such as by preventing crop from becoming wrapped up on the shaft assembly <NUM>. Additionally, each shaft assembly <NUM> includes a lower universal joint (not shown) housed within the cage <NUM> that provides for coupling of the shaft assembly <NUM> to a drive shaft <NUM>. The drive shaft <NUM> extends upward out of cage <NUM> and projects into a right-angle gearbox <NUM>. Inside the gearbox <NUM>, the drive shaft <NUM> operably connects with a horizontal output shaft <NUM> that ultimately drives the auger <NUM> and pair of conditioning rolls <NUM> and <NUM> (<FIG>) via a belt and pulley drive and a transmission box.

According to example embodiments described in detail here below, a cutter control system is provided to selectively drive gears <NUM>(a), <NUM>(b) at opposing ends of the gear train at different speeds. The cutter control system is described as including a drive arrangement <NUM> with rotary motors <NUM>, <NUM>, along with an associated controller and control system or circuit (hydraulic or electrical circuit) that collectively operate to pre-load the gears <NUM> of the gear train <NUM>, via driving of gears <NUM>(a), <NUM>(b) at different speeds. In various embodiments, the motors <NUM>, <NUM> may be in various configurations, including hydraulic motors or electric motors, as primary examples, although mechanically driven motors are also envisioned.

More specifically, the drive arrangement <NUM> drives the shafts <NUM> at each of opposing ends of cutter assembly <NUM>, along with the various components of the header <NUM> that derive power therefrom, including the rotary cutters <NUM> of cutter assembly <NUM>. Each of the motors <NUM>, <NUM> is carried on an elevated platform <NUM> that is coupled onto the topside of gearbox <NUM>, so that the motors <NUM>, <NUM> are disposed high above the crop handling region of the header <NUM>. Projecting downwardly from each motor <NUM>, <NUM> is drive shaft <NUM>, which extends through platform <NUM> and into gearbox <NUM>, before passing on down to the associated shaft assembly <NUM> and to the gear train <NUM> to transfer power thereto. The two motors <NUM>, <NUM> cooperatively drive and share the load of all of the rotary cutters <NUM> of the cutter assembly <NUM>, with the gear train <NUM> of the cutter assembly <NUM> receiving driving input power from the motors <NUM>, <NUM>. This means, for example, that the gear <NUM>(a) (shown in phantom in <FIG>) associated with the cutter <NUM>(a) does not need to bear all the loading from the other gears in the gear train <NUM> since approximately one half that loading is directed to the gear <NUM>(b) (shown in phantom in <FIG>) associated with the rotary cutter <NUM>(j) at the opposite end of the gear train <NUM>.

In operation of the cutter assembly <NUM>, it is recognized that it is desirable to drive the opposing ends of the gear train <NUM> (e.g., the outermost gears <NUM>, to which shaft assemblies <NUM> are coupled) at different speeds, with a first gear <NUM>(a) at one end and a second gear <NUM>(b) at the other end driven at different speeds during operation of the windrower <NUM>. That is, driving of second gear <NUM>(b) at a speed that is lower than the speed of first gear <NUM>(a) - or conversely driving of first gear <NUM>(a) at a speed that is lower than the speed of second gear <NUM>(b) - pre-loads the gears <NUM> of the gear train <NUM> into enmeshing engagement with each other in one rotational direction. Maintaining such a speed relationship between the gears <NUM>(a), <NUM>(b), such as maintaining gear <NUM>(b) at a speed slower than gear <NUM>(a), prevents the gears <NUM> from alternately being loaded in different directions during operation of the cutter assembly <NUM>, thereby eliminating gear chatter and reducing wear on the gears <NUM>.

In example embodiments described in further detail here below, motors <NUM>, <NUM> are operated at different speeds to provide for the gears <NUM>(a), <NUM>(b) being driven at different speeds. That is, motor <NUM> is operated at a speed that is lower than the speed of motor <NUM> - or conversely motor <NUM> is operated at a speed that is slightly lower than the speed of motor <NUM> - to provide the differential speeds of gears <NUM>(a), <NUM>(b). It is recognized, however, that in alternative embodiments, the driving of the gears <NUM>(a), <NUM>(b) at different speeds could be achieved in manners other than via the operation of motors <NUM>, <NUM> at different speeds. For example, motors <NUM>, <NUM> could be run at the same speed, but with a reduction gear (not shown) positioned between one of the motors <NUM>, <NUM> and its respective driven gear <NUM>(a), <NUM>(b) in the gear train <NUM> to result in one of the gears being driven at a slower speed.

In certain example embodiments, a cutter control system is provided in the form of a hydraulic circuit that drives a pair of rotary hydraulic motors <NUM>, <NUM> in drive arrangement <NUM>. Referring now to <FIG>, and with continued reference to <FIG>, an example embodiment of a hydraulic circuit <NUM> is illustrated for controlling operation of the hydraulic motors <NUM>, <NUM>. The hydraulic circuit <NUM> is illustrated as a closed-loop, hydrostatic system and is operable by hydraulic fluid, i.e., hydraulic oil, to enable running of motors <NUM>, <NUM> according to a desired operation. An onboard platform pump <NUM> is powered by a motor <NUM> (e.g., electric motor) that may be driven by the engine of the windrower <NUM> to provide for circulation of hydraulic oil within the circuit <NUM>, with the platform pump <NUM> being mechanically driven by the motor <NUM>. The platform pump <NUM> is preferably a pressure-compensated, load-sensitive pump that includes a swash plate <NUM> (denoted schematically for purposes of illustration by the arrow associated with the pump) that may be adjustably stroked or destroked to change its angular position and correspondingly adjust the output flow rate of oil therefrom as measured, for example, in gallons per minute. The variable flow output from platform pump <NUM> is achieved via electronic displacement control of the pump, with increases and decreases in the output flow providing more or less flow to the motors <NUM>, <NUM> to adjust the speed of the rotary cutters <NUM> on cutter assembly <NUM>. Other general components of the hydraulic circuit <NUM> include relief valves <NUM>, a charge pump <NUM>, and a charge pressure relief <NUM>, consistent with as known in a hydrostatic hydraulic circuit.

A controller <NUM> is provided in hydraulic circuit <NUM> to control operation of selected components therein, with it understood that controller <NUM> could be incorporated into the controller <NUM> of <FIG> or provided as a separate controller. The controller <NUM> may be configured as computing devices with associated processor devices <NUM>(a) and memory architectures <NUM>(b), as hydraulic, electrical or electrohydraulic controllers, or otherwise. As such, the controller <NUM> may be configured to execute various computational and control functionality with respect to the hydraulic circuit <NUM> and may be in electronic or hydraulic communication with various components therein. For example, in hydraulic circuit <NUM>, controller <NUM> provides for variable flow output from platform pump <NUM> via electronic displacement control thereof, with increases and decreases in the output flow providing more or less flow to the motors <NUM>, <NUM> to adjust the speed of the rotary cutters <NUM> on cutter assembly <NUM>. In various embodiments, controller <NUM> may also communicate with actuators, sensors, valves and other devices within the hydraulic circuit.

In the hydraulic circuit <NUM>, a high-pressure line <NUM> leads from the platform pump <NUM> to a tee connection <NUM>, where one fluid path <NUM> leads to the motor <NUM> and another fluid path <NUM> leads to the motor <NUM>. A mechanical-type flow divider <NUM> (e.g., rotary style flow divider) is positioned at tee connection <NUM> to divide a flow of hydraulic oil provided from platform pump <NUM>. In the illustrated embodiment, the flow divider <NUM> operates to provide a <NUM>-<NUM> split of the hydraulic oil to the fluid paths <NUM>, <NUM>, such that equal amounts of hydraulic oil flow along the fluid paths toward the motors <NUM>, <NUM>. Return lines <NUM> lead from the motors <NUM>, <NUM> back to another tee connection <NUM>, with a single return line <NUM> going to the backside of the pump <NUM>. A case drain line <NUM> is also connected to each of motors <NUM>, <NUM> and leads to a reservoir <NUM> that stores low pressure hydraulic oil. Hydraulic oil from return lines <NUM> and case drain lines <NUM> flows into/through relief valves <NUM>, charge pump <NUM>, charge pressure relief <NUM> and reservoir <NUM> in a known manner to remove any oversupply of oil to the pump <NUM> and to provide cooling for the pump.

As shown in <FIG>, to provide for differential operation of the motor <NUM> and the motor <NUM> in cutter assembly <NUM>, hydraulic circuit <NUM> includes an orifice valve (or more generally an "orifice") <NUM> in fluid path <NUM> that operates to restrict or control the flow of hydraulic oil provided to the motor <NUM>. The orifice <NUM> is positioned along a secondary fluid path <NUM> that is parallel to the motor <NUM> (i.e., positioned across motor <NUM>), such that a portion of hydraulic oil in fluid path <NUM> is diverted from an inlet <NUM> of motor <NUM> to flow along the secondary fluid path <NUM> and through orifice <NUM>, thereby bypassing motor <NUM> and being routed to join return line <NUM> at the outlet <NUM> of motor <NUM>. In the illustrated embodiment, the orifice <NUM> provides a restricted flow therethrough in a fixed amount, such that the amount of hydraulic oil diverted from the inlet <NUM> of motor <NUM> remains unchanged during operation of the motors <NUM>, <NUM> via hydraulic circuit <NUM>. As an example, orifice <NUM> may be set such that the flow of hydraulic oil therethrough results in the flow of hydraulic oil to the inlet <NUM> of motor <NUM> being <NUM>-<NUM>% less than the flow of hydraulic oil provided to motor <NUM>. This diverting or restriction of hydraulic fluid to motor <NUM> results in the motor operating at a reduced speed as compared to motor <NUM>, with the differential speed of motors <NUM>, <NUM> resulting in the gears <NUM>(a), <NUM>(b) being driven at different speeds and the gears <NUM> of the gear train <NUM> being pre-loaded into enmeshing engagement with each other in one rotational direction to prevent gear chatter, as described in detail previously.

Referring now to <FIG>, a hydraulic circuit <NUM> is provided according to another embodiment. The hydraulic circuit <NUM> is substantially similar to the hydraulic circuit <NUM> of <FIG>, and thus common components of the circuit are identified consistent with those in <FIG>. In hydraulic circuit <NUM>, the mechanical-type flow divider <NUM> divides a flow of hydraulic oil provided from platform pump <NUM> between fluid paths <NUM>, <NUM>, such that equal amounts of hydraulic oil flow along the fluid paths toward the motors <NUM>, <NUM>. In the embodiment of <FIG>, a (variable) orifice valve <NUM> is positioned in fluid path <NUM> that operates to restrict the flow of hydraulic oil provided to the motor <NUM>. Specifically, the orifice valve <NUM> is positioned along a secondary fluid path <NUM> that is parallel to the motor <NUM>, such that a portion of hydraulic oil in fluid path <NUM> is diverted from the inlet <NUM> of motor <NUM> to flow along the secondary fluid path <NUM> and through orifice valve <NUM>, thereby bypassing motor <NUM> and being routed to join return line <NUM> at the outlet <NUM> of motor <NUM>. The orifice valve <NUM> is configured to selectively restrict or control the flow of hydraulic oil therethrough by a desired amount and may be an electro-hydraulically controlled valve, for example.

Controller <NUM> of the hydraulic circuit <NUM> is operatively connected to the orifice valve <NUM> to adjust the valve and control the amount of hydraulic oil that flows therethrough. Adjustment of the orifice valve <NUM> may be performed responsive to inputs received by the controller <NUM> of one or more operational parameters that are measured during operation of the hydraulic circuit <NUM> and the motors <NUM>, <NUM>. For example, sensors may be included in hydraulic circuit that measure one or more of the speed of motors <NUM>, <NUM> and pressure(s) within the hydraulic circuit (and the load on the motors <NUM>, <NUM>) - with speed sensors <NUM> and pressure sensors <NUM> generally indicated in dashed lines in <FIG>, as non-limiting examples. The controller <NUM> may implement a transfer function that adjusts the orifice valve <NUM> responsive to these received inputs. For example, the controller <NUM> may adjust the orifice valve <NUM> as the cutter assembly <NUM> is loaded up on one side or as the load drops down. In a case where the load drops on motor <NUM> and the load rises on motor <NUM>, for example, the controller <NUM> will open the orifice valve <NUM> by an increased amount in order that more hydraulic oil is diverted from motor <NUM>, such that motor <NUM> continues to run slower than motor <NUM> and a directional pre-load on the gears is maintained in a constant fashion - i.e., so that motor <NUM> continues to provide a main driving force on gear train <NUM> and motor <NUM> provides a braking force. As an example, orifice valve <NUM> may be adjusted such that the flow of hydraulic oil therethrough results in the flow of hydraulic oil to the inlet <NUM> of motor <NUM> being maintained at <NUM>-<NUM>% less than the flow of hydraulic oil provided to motor <NUM>.

Referring now to <FIG>, a hydraulic circuit <NUM> is provided according to another embodiment. Again, the hydraulic circuit <NUM> is substantially similar to the hydraulic circuit <NUM> of <FIG>, and thus common components of the circuit are identified consistent with those in <FIG>. In hydraulic circuit <NUM>, the mechanical-type flow divider <NUM> divides a flow of hydraulic oil provided from platform pump <NUM> between fluid paths <NUM>, <NUM>, such that equal amounts of hydraulic oil flow along the fluid paths toward the motors <NUM>, <NUM>. In the embodiment of <FIG>, a (variable) orifice valve <NUM> is positioned in fluid path <NUM> that operates to restrict the flow of hydraulic oil provided to the motor <NUM>. The orifice valve <NUM> is positioned along a bypass fluid path <NUM> that is parallel to the motor <NUM>, with a portion of hydraulic oil in fluid path <NUM> being diverted from the inlet <NUM> of motor <NUM> to flow along the bypass fluid path <NUM> and through orifice valve <NUM>, thereby bypassing motor <NUM> and being routed or dumped directly into the case drain line <NUM> and back to reservoir <NUM>.

Similar to the orifice valve <NUM> of <FIG>, the orifice valve <NUM> is configured to selectively restrict or control the flow of hydraulic oil therethrough by a desired amount. In one embodiment, the orifice valve <NUM> is an electronically controlled valve in operable communication with controller <NUM>. The controller <NUM> operates to adjust the orifice valve <NUM> responsive to inputs thereto of one or more operational parameters (motor speed, hydraulic circuit pressure(s), etc.), with a transfer function of the controller <NUM> adjusting the orifice valve <NUM> responsive to these received inputs. As an example, orifice valve <NUM> may be adjusted such that the flow of hydraulic oil therethrough results in the flow of hydraulic oil to the inlet <NUM> of motor <NUM> being maintained at <NUM>-<NUM>% less than the flow of hydraulic oil provided to motor <NUM>. By varying the fluid flow through orifice valve <NUM>, hydraulic circuit <NUM> ensures that motor <NUM> continues to run slower than motor <NUM> and that a directional pre-load on the gears <NUM> is maintained in a constant fashion to pre-load the gears <NUM> of the gear train <NUM> into enmeshing engagement with each other in one rotational direction.

<FIG> illustrates another embodiment of a hydraulic circuit <NUM>. Again, the hydraulic circuit <NUM> is substantially similar to the hydraulic circuit <NUM> of <FIG>, and thus common components of the circuit are identified consistent with those in <FIG>. In hydraulic circuit <NUM>, the mechanical-type flow divider <NUM> divides a flow of hydraulic oil provided from platform pump <NUM> between fluid paths <NUM>, <NUM>, such that equal amounts of hydraulic oil flow along the fluid paths toward the motors <NUM>, <NUM>. In the embodiment of <FIG>, a (variable) orifice valve <NUM> is positioned in fluid path <NUM> that operates to bleed off a portion of the flow of hydraulic oil provided to the second motor <NUM>. The orifice valve <NUM> is positioned in a bleed-off fluid path <NUM> that is parallel to or across the flow divider <NUM>. Upon passing through the flow divider <NUM>, a portion of hydraulic oil in fluid path <NUM> is bled off and diverted back to high-pressure line <NUM> upstream from tee connection <NUM>. Accordingly, the flow of hydraulic oil in fluid path <NUM> provided to the inlet <NUM> of motor <NUM> can be reduced or restricted as compared to the flow of hydraulic oil in fluid path <NUM> that is provided to the motor <NUM>.

Similar to the orifice valves of <FIG> and <FIG>, the orifice valve <NUM> is configured to selectively restrict or control the flow of hydraulic oil therethrough by a desired amount. In one embodiment, the orifice valve <NUM> is an electronically controlled valve in operable communication with controller <NUM>. The controller <NUM> operates to adjust the orifice valve <NUM> responsive to inputs thereto of one or more operational parameters (motor speed, hydraulic circuit pressure(s), etc.), with a transfer function of the controller <NUM> adjusting the orifice valve <NUM> responsive to these received inputs. By varying the fluid flow through orifice valve <NUM>, hydraulic circuit <NUM> ensures that motor <NUM> continues to run slower than motor <NUM> to pre-load the gears <NUM> of the gear train <NUM> into enmeshing engagement with each other in one rotational direction.

Referring now to <FIG>, a hydraulic control system or hydraulic circuit <NUM> is provided according to another embodiment. The hydraulic circuit <NUM> includes a pair of onboard platform pumps <NUM>, <NUM> powered by a motor <NUM> that may be driven by the engine of the windrower <NUM> to provide for circulation of hydraulic oil within the hydraulic circuit <NUM>. Each of the platform pumps <NUM>, <NUM> may be configured as a variable displacement pump operable to provide a controlled amount of hydraulic oil to a respective motor <NUM>, <NUM> to run the motor according to a desired operation. Each of the pumps <NUM>, <NUM> may, for example, be a pressure-compensated, load-sensitive pump that includes a swash plate <NUM> that may be adjustably stroked or destroked to change its angular position and correspondingly adjust the output flow rate of oil therefrom. Other general components of the hydraulic circuit <NUM> include relief valves <NUM>, charge pump <NUM>, and charge pressure relief <NUM>.

The hydraulic circuit <NUM> includes a high-pressure line <NUM> leading from each pump <NUM>, <NUM> to its respective motor <NUM>, <NUM>, such that a first high-pressure fluid path <NUM> leads to the motor <NUM> and a second high-pressure fluid path <NUM> leads to the motor <NUM>. Return lines <NUM> lead from the motors <NUM>, <NUM> back to the backside of each of the respective pumps <NUM>, <NUM>. A case drain line <NUM> is also connected to each of motors <NUM>, <NUM> and leads to a reservoir <NUM> that stores low pressure hydraulic oil.

The variable flow output from each pump <NUM>, <NUM> is achieved via electronic displacement control of the pumps <NUM>, <NUM>, with increases and decreases in the output flow providing more or less flow to the motors <NUM>, <NUM>, to adjust the speed of the rotary cutters <NUM> on cutter assembly <NUM>. For providing such electronic displacement control, controller <NUM> is provided in the hydraulic circuit <NUM> that is operatively connected to the variable displacement pumps <NUM>, <NUM> to control the output flow rate of hydraulic oil therefrom. Controller <NUM> is programmed to control the output flow from the pumps <NUM>, <NUM> such that the output flow from pump <NUM> is always greater than the output flow from pump <NUM>. The controller <NUM> may adjust the output flow from the pumps <NUM>, <NUM> responsive to inputs received by the controller <NUM> in the form of an operator input (e.g., via controls in the cab <NUM>) and/or one or more operational parameters that are measured during operation of the hydraulic circuit <NUM> and the motors <NUM>, <NUM>. For example, sensors may be included in hydraulic circuit <NUM> that measure one or more of the motor speed of motors <NUM>, <NUM> and pressure(s) within the hydraulic circuit <NUM> - with speed sensors <NUM> and pressure sensors <NUM> generally indicated in dashed lines in <FIG>, as non-limiting examples. The controller <NUM> may adjust the output flow rate of one or more of the pumps <NUM>, <NUM> responsive to the received inputs and to maintain a leader-follower relationship between the speed of the motors <NUM>, <NUM>, i.e., that motor <NUM> always runs slower than motor <NUM>, to maintain a pre-load on the gears <NUM> in one rotational direction and thereby prevent gear chatter. As an example, one or more of the variable displacement pumps <NUM>, <NUM> may be adjusted such that the flow of hydraulic oil provided to motor <NUM> is <NUM>-<NUM>% less than the flow of hydraulic oil provided to motor <NUM>.

Another hydraulic circuit <NUM> is illustrated in <FIG>, where a high-pressure line <NUM> leads from a platform pump <NUM> to a tee connection <NUM>, with one fluid path <NUM> leading to the motor <NUM> and another fluid path <NUM> leading to the motor <NUM>. A priority valve <NUM> is positioned in fluid path <NUM> to control the flow of hydraulic oil to motor <NUM>, with priority valve <NUM> functioning to give motor <NUM> priority to motor <NUM> regarding a flow of hydraulic oil thereto. The priority valve <NUM> may be configured as an electronically controlled valve in operable communication with controller <NUM>. As previously described, controller <NUM> may adjust the flow through priority valve <NUM> responsive to inputs received by the controller <NUM> in the form of one or more operational parameters that are measured during operation of the hydraulic circuit <NUM> and the motors <NUM>, <NUM>. In operation of hydraulic circuit <NUM>, controller <NUM> controls the setting of priority valve <NUM> such that the flow of hydraulic oil provided to motor <NUM> through the valve is greater (e.g., <NUM>-<NUM>% greater) than the flow of hydraulic oil provided to motor <NUM>, with motor <NUM> thus running at an increased speed as compared to motor <NUM>.

Another hydraulic circuit <NUM> is illustrated in <FIG>, where a high-pressure line <NUM> leads from a platform pump <NUM> to a tee connection <NUM> having a flow divider <NUM> positioned thereat to divide a flow of hydraulic oil provided from platform pump <NUM>. In the illustrated embodiment, the flow divider <NUM> divides a flow of hydraulic oil from platform pump <NUM> between a fluid path <NUM> that leads to the motor <NUM> and a fluid path <NUM> that leads to the motor <NUM>. The flow divider <NUM> is configured to provide a differential flow between the two fluid paths <NUM>, <NUM>, with the flow divider <NUM> directing a greater flow of hydraulic oil to motor <NUM> and a lesser flow of hydraulic oil to motor <NUM>. The division of hydraulic oil between fluid paths <NUM>, <NUM> may be set at a fixed amount by flow divider <NUM>, with the flow of hydraulic oil provided to motor <NUM> being <NUM>-<NUM>% less than the flow of hydraulic oil provided to motor <NUM> as an example amount. Motor <NUM> is thereby caused to run slower than motor <NUM>, which applies a pre-load on the gears <NUM> of cutter assembly <NUM> in one rotational direction.

Another hydraulic circuit <NUM> is illustrated in <FIG>, where motors <NUM>, <NUM> are provided as variable displacement motors (e.g., variable displacement axial piston motors) that may be selectively controlled to vary the speeds therebetween. A high-pressure line <NUM> leads from a platform pump <NUM> to a tee connection <NUM> having a flow divider <NUM> positioned thereat to divide a flow of hydraulic oil provided from platform pump <NUM> between fluid path <NUM> that leads to the motor <NUM> and fluid path <NUM> that leads to the motor <NUM>. The flow divider <NUM> operates to provide a <NUM>-<NUM> split of the hydraulic oil to the fluid paths <NUM>, <NUM>, such that equal amounts of hydraulic oil flow to each motor <NUM>, <NUM>. The operation of variable displacement motors <NUM>, <NUM> to drive the rotary cutters <NUM> of cutter assembly <NUM> at a desired speed is achieved via electronic displacement control by controller <NUM>. Controller <NUM> is programmed to control the speed of motors <NUM>, <NUM> such that the speed of motor <NUM> is always greater than the speed of motor <NUM>. The controller may adjust the speeds of the variable displacement motors <NUM>, <NUM> responsive to inputs received by the controller <NUM> in the form of an operator input (e.g., via controls in the cab <NUM>) and/or one or more operational parameters that are measured during operation of the hydraulic circuit and the motors <NUM>, <NUM> (motor speeds and pressure(s) within the hydraulic circuit <NUM>). The controller <NUM> may adjust the speed of one or more of the motors <NUM>, <NUM> responsive to the received inputs and to maintain a constant relationship between the speed of the motors <NUM>, <NUM>, i.e., that motor <NUM> always runs slower than motor <NUM>, to pre-load the gears <NUM> of the gear train <NUM> into enmeshing engagement with each other in one rotational direction.

According to other embodiments, the motors <NUM>, <NUM> in cutter assembly <NUM> (<FIG>) are in the form of rotary electric motors <NUM>, <NUM>. Referring now to <FIG>, and with continued reference to <FIG>, an electric control system <NUM> for driving and controlling operation of the electric motors <NUM>, <NUM> is illustrated. The electric control system <NUM> receives power from the mechanical motion of the engine in windrower <NUM> and converts and conditions that power into an electric power suitable for use by the electric motors <NUM>, <NUM>. In electric control system <NUM>, a generator <NUM> converts mechanical energy from the windrower engine to electric power in the form of alternating current (AC) power. The AC power output from generator <NUM> is provided to a pair of motor drives <NUM>, <NUM>, with motor drive <NUM> providing a controlled power input to motor <NUM> and motor drive <NUM> providing a controlled power input to motor <NUM>.

In the illustrated embodiment, each of motor drives <NUM>, <NUM> is an adjustable speed drive (ASD) designed to receive an AC power input from the generator <NUM>, rectify the AC input, and perform a DC/AC conversion of the rectified segment into a three-phase alternating voltage of variable frequency and amplitude that is supplied to its associated electric motor <NUM>, <NUM>. In operation, AC power input from the generator <NUM> is fed to a rectifier bridge <NUM> that converts the AC power input to a DC power, such that a DC link voltage is present between rectifier bridge <NUM> and a switch array <NUM>. The DC link voltage is then buffered or smoothed by a DC link capacitor bank <NUM> and provided to switch array <NUM>, which includes a series of IGBT switches (for example) and anti-parallel diodes that collectively form a PWM inverter <NUM>. PWM inverter <NUM> controls IGBT switches to synthesize variable-frequency, variable-amplitude DC voltage waveforms that are delivered to its associated motor <NUM>, <NUM> following a constant Volts-per-Hertz or vector controls with or without speed/position sensors algorithm. In this regard, the motor drives <NUM>, <NUM> provide voltage regulation in steady state and fast dynamic step load response over a full load range.

As shown in <FIG>, controller <NUM> in electric control system <NUM> is operatively coupled with the motor drives <NUM>, <NUM> to provide control functions thereto. Controller <NUM> is programmed to operate motor drives <NUM>, <NUM> to provide a controlled power (controlled voltage and/or current) to motors <NUM>, <NUM> to control the speed (or torque) of the motors for driving rotary cutters <NUM>, such as according to operator inputs (e.g., via controls in the cab <NUM>) received thereby. Additionally, controller <NUM> is programmed to operate motor drives <NUM>, <NUM> to provide a controlled power to motors <NUM>, <NUM> to operate the motors such that the speed (or torque) of motor <NUM> is always greater than the speed (or torque) of motor <NUM>, such as by a value of <NUM>-<NUM>%. To maintain motor <NUM> at a higher speed (or torque) than motor <NUM>, controller <NUM> receives one or more operational parameters that are measured during operation of the motors <NUM>, <NUM>. Sensors may be included in electric control system <NUM> that measure one or more of the speed or torque of motors <NUM>, <NUM> - with speed sensors <NUM> and torque sensors <NUM> generally indicated in dashed lines in <FIG>. The controller <NUM> may adjust the speed (or torque) of one or more of motors <NUM>, <NUM> responsive to the received inputs and to maintain a leader-follower relationship between the motors <NUM>, <NUM> (e.g., that motor <NUM> always runs slower than motor <NUM>) to pre-load the gears <NUM> of the gear train <NUM> into enmeshing engagement with each other in one rotational direction and thereby prevent gear chatter.

A dual motor drive of a cutter assembly included in a harvesting header may be controlled according to a number of methods. A first motor of the dual motor drive is caused to operate at a speed that is greater than a speed of the second motor, and this speed differential between the motors is maintained during operation of the header such that such that the first motor always applies a main driving force to the gear train of the cutter assembly and the second motor always applies a secondary driving force (i.e., braking force) to the gear train of the cutter assembly. The speed differential between the motors causes a directional pre-load to be applied onto the gears of the gear train, and this directional pre-load is maintained during operation of the header. Chatter between the gears is thus prevented, thereby reducing wear on the gears and increasing the longevity thereof.

Embodiments include a hydraulic control system (hydraulic circuit) that controls operation of first and second hydraulic motors of the cutter assembly. Methods for controlling operation of the hydraulic motors of the cutter assembly may be implemented by any of the hydraulic circuits illustrated in <FIG>. In embodiments, the flow of hydraulic oil to the first motor and second motor of the cutter assembly is controlled via the use of valves (a fixed or variable orifice valve or a priority valve) that restrict the flow of oil to one of the motors or prioritize the flow of oil to one of the motors, to achieve the differential flow of hydraulic oil to the motors. In other embodiments, the flow of hydraulic oil to the first motor and second motor of the cutter assembly is controlled via the use of one or more variable displacement pumps that provide an increased flow of oil to one of the motors, to achieve the differential flow of hydraulic oil to the motors. In other embodiments, the flow of hydraulic oil to the first motor and second motor of the cutter assembly is controlled via the use of a flow divider that diverts differing amounts of oil to the two motors, to achieve the differential flow of hydraulic oil to the motors. In other embodiments, the first motor and second motor of the cutter assembly are variable displacement motors that are operated according to a differential electronic displacement control scheme, such that the first motor operates at a higher speed than the second motor. In embodiments, dynamic control of the hydraulic motors is enabled via the acquisition and analysis of one or more operational parameters of the hydraulic circuit (motor speed, system pressure, etc.), to maintain a desired differential speed relationship between the motors.

Other embodiments have an electric control system that controls operation of first and second electric motors of the cutter assembly. Methods for controlling operation of the electric motors of the cutter assembly may be implemented by the electric control system illustrated in <FIG>. Power provided to the first and second motors is controlled (via operation of motor drives associated with the electric motors) to operate the motors such that the speed (or torque) of the first motor is always greater than the speed (or torque) of the second motor. In embodiments, dynamic control of the electric motors is enabled via the acquisition and analysis of one or more operational parameters of the motors (motor speed, motor torque), to maintain a desired differential speed relationship between the motors.

The following examples are provided, which are numbered for ease of reference.

The foregoing has thus provided a work vehicle for cutting crop material featuring a header with a cutter assembly having a series of rotary cutters driven by a gear train that receives power from first and second motors of a cutter control system. The cutter control system operates to drive a first gear of the gear train at a first speed via the first motor and drive a second gear of the gear train at a second speed via the second motor, with the second speed being different than the first speed to pre-load the gear train into enmeshing engagement with each other in one rotational direction, thereby reducing or eliminating gear chatter and reducing the wear on the gears associated therewith.

Claim 1:
A work vehicle for cutting crops comprising:
a header (<NUM>) supported by a chassis (<NUM>) of the work vehicle (<NUM>), the header (<NUM>) including a cutter assembly (<NUM>) comprising:
a cutter bar frame (<NUM>);
a series of rotary cutters (<NUM>) mounted on the cutter bar frame (<NUM>) and arranged in a lengthwise direction; and
a gear train (<NUM>) coupled to the series of rotary cutters (<NUM>) to transfer power thereto, the gear train (<NUM>) having a first gear (60a) and a second gear (60b);
a cutter control system comprising:
a first motor (<NUM>) coupled to the first gear (60a) of the gear train (<NUM>) to provide power to the gear train (<NUM>); and
a second motor (<NUM>) coupled to the second gear (60b) of the gear train (<NUM>) to provide power to the gear train (<NUM>); and
a controller (<NUM>, <NUM>), including a processor (100a) and memory architecture (100b), operably connected to the first motor (<NUM>) and the second motor (<NUM>) to control operation thereof;
the work vehicle being characterised in that the cutter control system is configured to drive the first gear (60a) at a first speed via the first motor (<NUM>) and to drive the second gear (60b) at a second speed via the second motor (<NUM>), the second speed being different than the first speed to pre-load the gear train (<NUM>) into enmeshing engagement with each other in one rotational direction.