US 12,133,482 B2
Trimmer head and string trimmer
Jianpeng Guo, Nanjing (CN)
Assigned to Nanjing Chervon Industry Co., Ltd., Nanjing (CN)
Filed by Nanjing Chervon Industry Co., Ltd., Nanjing (CN)
Filed on Sep. 10, 2020, as Appl. No. 17/017,208.
Claims priority of application No. 201910877763.7 (CN), filed on Sep. 17, 2019; application No. 201921550134.5 (CN), filed on Sep. 17, 2019; and application No. 201921550166.5 (CN), filed on Sep. 17, 2019.
Prior Publication US 2021/0076564 A1, Mar. 18, 2021
Int. Cl. A01D 34/416 (2006.01)
CPC A01D 34/416 (2013.01) [A01D 34/4165 (2013.01)] 10 Claims
OG exemplary drawing
 
1. A trimmer head, comprising:
a spool defining a central connecting hole configured to accept a drive shaft that is rotatable about a rotation axis, the spool being manufactured with an imbalance about the rotation axis and provided with a plurality of first transmission teeth; and
a head housing for accommodating at least a part of the spool, the head housing being provided with a plurality of second transmission teeth for engaging with the plurality of first transmission teeth,
wherein, when the trimmer head rotates about the rotation axis and along a predetermined direction, the plurality of first transmission teeth engage with the plurality of second transmission teeth to transmit a force (F1) between the head housing and the spool, each of the plurality of first transmission teeth is formed with a first contact surface, each of the plurality of second transmission teeth is formed with a second contact surface for contacting with the first contact surface, the force (F1) acting on a point of action of the first contact surface or the second contact surface to drive the head housing and the spool to rotate synchronously along the predetermined direction, the force (F1) is perpendicular to the first contact surface, in a circle around the rotation axis and passing through the point of action, a radial direction connecting the point of action and the rotation axis is defined as a first direction, a tangent direction of the circle at the point of action is defined as a second direction, the second direction is perpendicular to the first direction, and
wherein a plane of the first contact surface does not pass through the central connecting hole such that the force (F1) perpendicular to the first contact surface is not perpendicular to the first direction, the force (F1) has a first component force (F2) along the first direction and a second component force (F3) along the second direction to drive one of the head housing and the spool to rotate with the other, and the first component force (F2) is at least capable of offsetting an eccentric force (F0) between the head housing and the spool generated as a product of the imbalance and rotation of the spool.