Automatic feed system for a trimmer
An automatic feed system for a trimmer is provided. Such trimmers include a line that can be spun at high speeds to cut vegetation along roadsides or other areas. The automatic feed system is configured to dynamically detect the current length of the line and automatically feed the line to maintain a maximum or desired length for cutting. This length may typically correspond with the radius of a trimmer deck in which the line spins.
1 . A trimmer having an automatic feed system comprising:
a line that is configured to be spun to cut vegetation, the line also being configured to be fed to extend a length of the line;
a drive motor that causes the line to be spun;
one or more line securing members through which the line is fed;
a feed motor that controls the one or more line securing members including to apply a holding force to the one or more line securing members to prevent the line from being fed; and
a control system that is configured to monitor the holding force applied by the feed motor while the line is spun by the drive motor and to determine, from the holding force, when the line is less than a maximum or desired length, including by using a current holding force and a known holding force associated with a known length of the line, wherein the control system is also configured to automatically feed the line based on the holding force to reach the maximum or desired length, wherein the current holding force is a force applied by or through the feed motor to cause the one or more line securing members to prevent the line from being fed while the line is spun, and wherein the known holding force is associated with the line having the maximum or desired length.
2 . The trimmer of claim 1 , wherein the one or more line securing members comprise one of:
opposing gears or rollers;
a rotating member with an opposing securing mechanism; or
opposing pinch members.
3 . The trimmer of claim 2 , wherein the one or more line securing members are opposing gears or rollers, and wherein the line is pinched between the opposing gears or rollers.
4 . The trimmer of claim 1 , wherein the control system is configured to monitor a speed at which the line is spun.
5 . The trimmer of claim 4 , wherein monitoring the speed at which the line is spun comprises monitoring the drive motor.
6 . The trimmer of claim 5 , wherein monitoring the drive motor comprises monitoring a torque created by the drive motor to cause the line to be spun at the speed.
7 . The trimmer of claim 1 , wherein automatically feeding the line based on the holding force to reach the maximum or desired length comprises one of:
causing the one or more line securing members to rotate;
ceasing to prevent the one or more line securing members from rotating;
separating the one or more line securing members; or
reducing a pinching force that the one or more line securing members apply to the line.
8 . The trimmer of claim 1 , wherein determining from the holding force when the line is less than the maximum or desired length comprises using an amount of the holding force when the line is at the maximum or desired length.
9 . The trimmer of claim 1 , wherein the control system is configured to automatically feed the line until the holding force corresponds to the known holding force associated with the known length of the line.
10 . The trimmer of claim 1 , wherein determining when the line is less than the maximum or desired length comprises determining that the length of the line has fallen below a threshold relative to the maximum or desired length.
11 . A trimmer having an automatic feed system comprising:
a line that is configured to be spun to cut vegetation, the line also being configured to be fed to extend a length of the line;
a drive motor that causes the line to be spun;
one or more line securing members through which the line is fed;
a feed motor that controls the one or more line securing members including to apply a holding force to the one or more line securing members to prevent the line from being fed; and
a control system that is configured to automatically feed the line by:
monitoring a current holding force applied by the feed motor to prevent the line from being fed while the line is spun and has an unknown length;
obtaining a known holding force associated with preventing a line from being fed while the line is spun and has a known length;
calculating, from the current holding force and the known holding force, a current length of the line; and
automatically feeding the line to cause the line to have a maximum or desired length;
wherein the current holding force is a force required by the feed motor to cause the one or more line securing members to prevent the line from being fed while the line is spun and has the unknown length, and wherein the known holding force represents a force required by a feed motor to cause one or more line securing members to prevent a line from being fed while the line is spun and has the known length, the known length being the maximum or desired length.
12 . The trimmer of claim 11 , wherein calculating the current length of the line comprises calculating the current length as an absolute length or as a length relative to the maximum or desired length.
13 . The trimmer of claim 11 , wherein the control system automatically feeds the line also by:
monitoring a current speed of the line;
wherein the known holding force corresponds with the current speed.
14 . The trimmer of claim 11 , wherein automatically feeding the line comprises causing the one or more line securing members to allow the line to be fed.
15 . The trimmer of claim 11 , wherein the known holding force comprises a stored value obtained using a calibration process performed on another trimmer.
16 . An automatic feed system for a trimmer comprising:
a line feed unit that is secured to a deck, the line feed unit containing a line and being configured to rotate relative to the deck to cause the line to spin within the deck;
a drive motor that is configured to cause the line feed unit to rotate;
one or more line securing members through which the line passes;
a feed motor that is configured to control the one or more line securing members including to apply a holding force to the one or more line securing members to prevent the line from being fed;
a control system that is configured to monitor the drive motor and the holding force applied by the feed motor to determine a current length of the line based on a current holding force and a known holding force associated with a known length of the line, wherein the control system is also configured to automatically feed the line when the current length of the line is determined to be less than a maximum or desired length, wherein the current holding force is a force applied by or through the feed motor to cause the one or more line securing members to prevent the line from being fed while the line is spun, and wherein the known holding force is associated with the line having the maximum or desired length.
17 . The automatic feed system of claim 16 , wherein the control system monitors a force of the drive motor.
18 . The automatic feed system of claim 16 , wherein the control system causes the feed motor to cause the one or more line securing members to allow the line to be fed.
19 . The automatic feed system of claim 16 , wherein the one or more line securing members are one of:
opposing gears or rollers that pinch the line;
opposing pinch members that pinch the line; or
a rotating member with an opposing securing mechanism that pinch the line.
20 . The automatic feed system of claim 16 , wherein the control system is configured to generate a feed command defining one of an amount by which the feed motor should rotate the one or more line securing members, a duration of time that the one or more line securing members should allow the line to be fed, or a length of line to be fed.