The present invention relates generally to line trimmers for cutting vegetation and, more particularly, relates to spools having filament wound thereon which are installed to hubs of trimmers.
Vegetation trimmers are in common use for cutting vegetation in areas that are difficult to reach such as along houses, sidewalks, or around trees and bushes. Bump feed trimmers are convenient because when the cutting filament wears down, the user simply taps the vegetation trimmer against a hard surface to feed more cutting filament into the cutting plane. However, the user will eventually use all of the filament he initially wound around the spool, thus creating the need to wind more filament around the spool. Currently this is a difficult and tedious task because the bolt constraining the hub and spool assembly can become extremely tight as the vegetation trimmer is used, as well as the difficulty of tracking many small parts that are removed just to remove the spool.
Fixed line vegetation trimmers have been developed to address the problem of having to disassemble the hub and spool assembly. Fixed line vegetation trimmers do not have a complex hub and spool assembly. Fixed line trimmers have a hub which clamps a plurality of fixed length filaments. Fixed line vegetation trimmers are often configured such that the user simply inserts the filament into the clamp. The problem associated with this configuration is that the user has to stop more frequently to load new filament because he cannot simply tap the vegetation trimmer against a hard surface to feed more cutting filament into the cutting plane.
Easy feed vegetation trimmers have been developed to address the problem of having to disassemble the hub and spool assembly. The user inserts a length of filament through an aperture in the hub, through the center of the spool, and through the aperture in the hub directly opposite to the first aperture in the hub. The user then simply twists the spool to wind the line onto the spool. While using an easy feed vegetation trimmer, the user taps the vegetation trimmer against a hard surface to feed more filament into the cutting plane. The problem with this configuration is that it can still become difficult to disassemble if the need arises, and there are still many small parts that are removed.
The present invention addresses the issue of having to disassemble the hub and spool assembly when the need arises. All of the small parts are contained in the hub and spool assembly when the spool is removed. Arms on the hub selectively engage with arms on the spool to limit the axial movement of the spool, but still allow for normal operation of the vegetation trimmer. The spool is quickly removed when the user rotates the spool to one direction such that the arms on the hub no longer axially constrain the spool. Additionally, the user can be carrying an extra spool that has already been wound with filament. This would reduce the need for the user to wind new filament on the spool at the point in time he uses all the filament he initially wound around the spool. He simply inserts the extra spool into the hub and rotates it such that the arms on the hub engage with arms on the spool to limit the axial movement of the spool.
A vegetation trimmer with a hub and spool is provided. The spool is rotationally locked relative to the hub in said first position and is allowed to rotate relative to the hub in said second position. At least one cutting filament is wound around the spool and extends radially outward into the cutting plane. Arms on the hub selectively engage with arms on the spool to limit the axial movement of the spool relative to the hub. The spool is quickly removed from the hub when the user rotates the spool relative to the hub such that the arms on the hub no longer limit the axial movement of the spool. Alternately, the spool can be quickly removed from the hub when the user provides a sufficient axial force to the spool in a direction away from the hub. Examples are shown in
Preferably, arms on the hub engage with arms on the spool to axially constrain the spool to the hub in said first position. When the spool is acted upon, the spool moves axially toward the hub and arms on the hub no longer engage with arms on the spool to rotationally lock the spool relative to the hub. As the spool rotates relative to said hub in said second position, arms on the spool strike arms on the hub after a predetermined amount of relative rotation has been achieved. A biasing member biases the spool away from the hub and the spool enters into said first position. To remove the spool from the hub and spool assembly, the user rotates the spool relative to the hub in a direction opposite of the relative rotation that occurs in the second position to disengage arms on the hub from arms on the spool. Indicators such as arrows can be provided to remind the user which way to rotate the spool to achieve this effect. The biasing member will continue to bias the spool away from the hub to assist the user with quick removal.
Those skilled in the art will appreciate that the present invention can be expanded such that arms on the spool selectively engage with arms on other parts of the hub and spool assembly to limit the axial movement of the spool relative to the hub. This would allow for a wide range of designs that would allow a retrofit onto any existing vegetation trimmer. Examples of expansions of the current invention described above are shown in
Alternately, the biasing member can be rigidly attached to the hub and spool assembly. A groove is provided in the spool to provide for a tight fit of the biasing member to the spool. The friction from the tight fit would be such that it contains the spool to the hub and spool assembly while the vegetation trimmer is being operated, but the friction would not be so great that the user cannot easily remove the spool by hand. This example of an alternate way of attaching the spool to the hub and spool assembly is shown in
Arms on the hub and spool assembly can be made out of a material such that when a sufficient axial force is applied to the spool, arms on the spool deform the material to allow for axial movement of the arms on the spool through the axial positions normally limited by the arms on the hub and spool assembly. This is illustrated in
An object of this invention is to create a hub and spool assembly such that the spool can be quickly removed from the hub and spool assembly. The amount of time spent refreshing the filament on the vegetation trimmer is significantly reduced, thus significantly reducing the amount of time required to cut an area of vegetation.
Another object of this invention is to create a hub and spool assembly such that when the filament is exhausted from the spool, the user does not have to wind new filament on the spool at that point in time. The user can carry a spool that has already been wound with filament and simply insert the new spool into the hub and spool assembly. This would allow the user to choose a more convenient time to wind the spool with cutting filament. One example would be a yard cutting service winding several spools with filament in between jobs instead of in the middle of trimming a yard.
Another object of this invention is to create a hub and spool assembly such that the spool can be positioned to axial positions other than those required for cutting vegetation and feeding additional cutting filament into the cutting plane. One example of an alternate implementation of the current invention (see
Another object of this invention is to create alternatives for attaching the hub and spool assembly to the vegetation trimmer such that the hub and spool assembly can be removed and/or disassembled by hand.
The following US patents are relevant to the inner workings of string line trimmers: U.S. Pat. No. 4,047,299; U.S. Pat. No. 4,272,201; U.S. Pat. No. 4,524,515; U.S. Pat. No. 4,633,588; U.S. Pat. No. 4,656,739; U.S. Pat. No. 5,020,223; U.S. Pat. No. 5,339,526; U.S. Pat. No. 5,987,756; U.S. Pat. No. 6,094,823, U.S. Pat. No. 7,111,403, and U.S. Pat. No. 8,176,639.
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