Patent Application
20240114825
The present invention relates to grass mowing machines, and more specifically to a radial frequency of clip control system for grass mowing machines with a plurality of reel cutting units such as triplex greensmowers.
Grass mowing machines used to mow golf courses, parks, and athletic fields where a high quality of cut is desired, may include three or more reel cutting units. For example, triplex greensmowers have two forward reel cutting units followed by a center or rear reel cutting unit positioned under the vehicle frame and the operator station. Reel cutting units have front and rear rollers, spiral cutting blades rotating in close proximity to a bedknife, and may have a removable grass catcher mounted in front of the cutting unit. For example, a reel cutting unit may have 8 spiral cutting blades.
Frequency of clip is the distance traveled by a cutting reel between consecutive clips by the spiral cutting blades. The frequency of clip may depend on the number of blades on the reel, the reel rotational speed or rpm, and the travel or ground speed of the greensmower or other vehicle. If frequency of clip is not within a specified range, there may be negative effects. For example, if frequency of clip is too slow, the grass may have a rippled effect sometimes referred to as marcelling or wash boarding. If frequency of clip is too fast, the grass may be over stressed and develop stripes and/or brown tips, and the reel cutting unit also may experience accelerated component wear.
In the past, some greensmowers have use the desired vehicle mow speed to calculate frequency of clip, which results in the same reel rotational speed or rpm value commanded to all of the reel cutting units. However, during turns, reel cutting units that are offset from the vehicle centerline will travel along the ground at a larger or smaller radius compared to the vehicle centerline. Those reel cutting units will travel faster or slower than the vehicle, and will have a larger or smaller frequency of clip.
There is a need for a radial frequency of clip control system that provides the same frequency of clip for reel cutting units when mowing in a straight line or turning. There is a need for a radial frequency of clip control system that provides the same frequency of clip for a plurality of reel cutting units that travel along the ground at a larger or smaller radius compared to the vehicle centerline.
A radial frequency of clip control system includes a controller that provides a plurality of different rotational speed commands to a plurality of reel cutting units based on a sensor input for a turning angle of a steerable rear wheel of a grass mowing machine and a calculated distance of each reel cutting unit to an instantaneous turn center.
In one embodiment, radial frequency of clip control system 100 may include a sensor input to controller 105 for the angle ϕ1 of steerable rear wheel 110. The controller may use angle ϕ1 to determine the location of point 0, the instantaneous turn center of the triplex greensmower or other grass mowing machine. In
In one embodiment, radial frequency of clip control system 100 may include a pedal input to the controller for desired ground speed Vveh at reference point VEH. Reference point VEH may be located anywhere on the centerline of a triplex greensmower or other grass mowing machine, rearward of front wheel axis FA. To minimize centrifugal force and improve operator feel, reference point VEH may be located near the operator seat. For example, the grass mowing machine may include a display or input device to the controller, which the operator may use to enter the desired location of VEH, or move the location forward or rearward.
In one embodiment, the radial frequency of clip control system may include a controller that calculates the ground speed VFA at the centerline of the front drive wheel axis, based on desired ground speed Vveh at reference point VEH, and angle ϕ2 from VEH to point 0. To calculate the ground speed VFA at the centerline of the front drive wheel axis, the controller may use the equation VFA=cos (ϕ2)*Vveh.
In one embodiment, the radial frequency of clip control system may include a reference point on each of the plurality of reel cutting units. For example,
In one embodiment, the radial frequency of clip control system may include a controller that calculates the distance from the reference point on each reel cutting unit to point 0, the instantaneous turn center. The controller first may calculate R0, the distance from the mower centerline to point 0, using the equation R0=CML*tan(ϕ1); AL, the distance parallel to the front axis from reference point PL to point 0, using the equation AL=R0+DL; and AR, the distance parallel to the front axis from reference point PR to point 0, using the equation AR=R0−DR. The controller then may calculate CL, the distance from reference point PL to point 0, using the equation CL=√{square root over (AL2+BF2)}, CR, from reference point PR to point 0, using the equation CR==√{square root over (AR2+BF2)}, and CC, from reference point PC to point 0, using the equation CC==√{square root over (RO2+BR2)}.
In one embodiment, the radial frequency of clip control system may include a controller that calculates the rotational speed of each reel cutting unit to maintain the same specified frequency of clip when turning. The rotational speed of each reel cutting unit may be based on the distance from the reference point on each reel cutting unit to point 0, the instantaneous turn center. The controller can adjust the rotational speed of each reel to maintain the desired frequency of clip when turning. For example, the controller may calculate the rotational speed OR of the right front reel cutting unit using the equation ωR=(CR/R0)*(VFA*1056)/(FOC*#Blades); the rotational speed ωL of the left front reel cutting unit using the equation ωL=(CL/R0)*(VFA*1056)/(FOC*#Blades); and the rotational speed ωC of the center or rear reel cutting unit using the equation ωC=(CC/R0)*(VFA*1056)/(FOC*#Blades).
The radial frequency of clip control system includes a controller that provides the same frequency of clip for all reel cutting units, when mowing in a straight line and when turning. The controller commands the speed for each reel cutting unit based on the distance of the reel cutting unit to point 0, the instantaneous turn center of the mower.
Having described the preferred embodiment, it will become apparent that various modifications can be made without departing from the scope of the invention as defined in the accompanying claims.
