Automatic line feed for trimmer

Patent metadata

Field	Value
Publication number	US-10918015-B2
Application number	US-201615763964-A
Country	US
Kind code	B2
Filing date	Oct 6, 2016
Priority date	Oct 8, 2015
Publication date	Feb 16, 2021
Grant date	Feb 16, 2021

Abstract

A trimmer head arranged to be driven to rotate a trimmer line, where the trimmer head includes a housing and an inner body connected to a trimmer line spool. The inner body is arranged to be movable relative the housing so that a trimmer line spooled around the trimmer line spool is released and pulled out by a centrifugal force caused by the rotation of the trimmer head, thereby allowing feed of the trimmer line. The trimmer further includes drive means for driving the trimmer head to rotate, and the trimmer is arranged to cause a relative movement of the inner body relative the housing by changing the rotation speed of the trimmer head.

First claim

The invention claimed is:

1. A trimmer head of a trimmer, the trimmer head comprising:
a housing comprising an upper housing and a lower housing, the upper housing configured to be coupled to a lower housing;
an inner body arranged within the upper housing and the lower housing and configured to rotate via a drive shaft of the trimmer;
a torsion spring coupled to the housing and disposed axially relative to an axis of rotation of the drive shaft; and
a trimmer line spool arranged within the upper housing and the lower housing and comprising trimmer line spooled around the trimmer line spool,
wherein, in response to a cutting operation of the trimmer head, the housing, the inner body, and the trimmer line spool are rotatably coupled, and
wherein in response to a user of the trimmer initiating a feed of the trimmer line, a spring bias of the torsion spring applied to the housing is overcome due to a centrifugal force to disengage an interaction with a stop disposed on the trimmer line spool and rotate the trimmer line spool independently of the housing to release the trimmer line spooled around the trimmer line spool.

2. The trimmer according to claim 1 , wherein in response to the user of the trimmer initiating a feed of the trimmer line, a rotation direction or a rotation speed of the drive shaft is configured to change.

3. The trimmer according to claim 2 , wherein the trimmer is further configured to change the rotation speed by accelerating the rotation speed at a rate higher than during the cutting operation or by decelerating the rotation speed at a rate higher than during the cutting operation.

4. The trimmer according to claim 3 , wherein the trimmer is further configured to change the rotation speed by increasing the rotation speed momentarily.

5. The trimmer according to claim 3 , wherein the trimmer is further configured to change the rotation speed by:
increasing the rotation speed momentarily to a boosted speed level;
reduce the rotation speed at maximum deceleration;
accelerate the rotation speed to the boosted speed level; and then
returning to the rotation speed associated with the cutting operation.

6. The trimmer according to claim 1 , wherein the trimmer is a garden trimmer.

7. The trimmer according to claim 1 , wherein the trimmer is an electric trimmer.

8. The trimmer according to claim 1 , wherein the trimmer is a combustion engine powered trimmer.

9. A trimmer head according to claim 1 , wherein the trimmer head further comprises a locking lever mounted in the upper housing, wherein the trimmer line spool comprises a recess in which the one or more stops are disposed, wherein a portion of the locking lever passes through the inner body to extend into the recess of the trimmer line spool, wherein in response to the cutting operation of the trimmer head, the locking lever has a rest position against one of the one or more stops of the trimmer line spool, and wherein in response to the user of the trimmer initiating the feed of the trimmer line, the locking lever is removed from the rest position and trimmer line spool is configured to rotate independently of the upper housing, the lower housing, and the inner body.

10. The trimmer head according to claim 9 , wherein the trimmer head further comprises a spring holding member arranged in the upper housing.

11. The trimmer head according to claim 10 , wherein the trimmer head further comprises a locking lever arranged to cooperate with the spring holding member to enable the locking lever to be removed from a rest position.

12. A method for controlling a trimmer comprising a trimmer head comprising a housing, the housing comprising an upper housing and a lower housing, the upper housing being coupled to a lower housing, the trimmer further comprising a torsion spring coupled to the housing and disposed axially relative to an axis of rotation of the drive shaft, a trimmer line spool arranged within the upper housing and the lower housing and comprising a trimmer line spooled around the trimmer line spool, and an inner body arranged within the upper housing and the lower housing and configured to rotate via a drive shaft of the trimmer, the method comprising:
operating the trimmer head at a rotation direction and a rotation speed associated with a cutting operation, wherein, in response to the cutting operation, the housing, the inner body, and the trimmer line spool are rotatably coupled;
receiving an input that the trimmer line of the trimmer line spool is to be fed; and
in response to receiving the input that the trimmer line is to be fed, changing either the rotation speed or the rotation direction of the drive shaft causing a spring bias of the torsion spring applied to the housing to be overcome due to a centrifugal force to disengage an interaction with a stop disposed on the trimmer line spool and rotate the trimmer line spool independently of the housing, thereby releasing the trimmer line spooled around the trimmer line spool.

13. The method according to claim 12 , wherein the method further comprises changing the rotation speed by reversing the rotation direction.

14. The method according to claim 12 , wherein the method further comprises changing the rotation speed by accelerating the rotation speed momentarily.

15. The method according to claim 12 , wherein the method further comprises changing the rotation speed by:
accelerating the rotation speed momentarily to a boosted speed level;
reduce the rotation speed at maximum deceleration;
accelerate the rotation speed to the boosted speed level; and then
returning to the rotation speed associated with the cutting operation.

Assignees

• Husqvarna Ab

Inventors

• Hallendorff Johan
• Wykman Tomas
• Kullberg Stefan
• Skogward Rickard

Classifications

• A01D34/416 Primary

  Flexible line cutters · CPC title

• A01D34/4162 Primary

  automatically · CPC title

• A01D34/4161

  Means for feeding cutter line · CPC title

• A01D34/4163

  by triggered line feedout, e.g. bump-feeding · CPC title