Grass trimmer and cord delivering method of grass trimmer

Patent metadata

Field	Value
Publication number	US-9872429-B2
Application number	US-201615236972-A
Country	US
Kind code	B2
Filing date	Aug 15, 2016
Priority date	May 16, 2014
Publication date	Jan 23, 2018
Grant date	Jan 23, 2018

Abstract

The invention provides a grass trimmer and a cord delivering method for a grass trimmer, the grass trimmer comprises an extending rod, an housing, a grass trimming head, a handle, a main motor and a main switch, wherein the grass trimming head comprises a base, a cap and a spool having a first state relative static with the base, and the grass trimmer further comprises a cord delivering mechanism; the cord delivering mechanism comprises a cord delivering electronic switch independent of the main switch and a control device; and the cord delivering electronic switch operably electrically controls the control device to enable the spool to be in a second state capable of generating a rotary speed difference with the base. An operator does not need to interrupt work of the grass trimmer and can timely pay off required and the cord delivering operation is simple and convenient.

First claim

What is claimed is:

1. A grass trimmer, comprising:
an extending rod extending longitudinally;
a housing arranged at one end of said extending rod;
a handle arranged on said extending rod and spaced from said housing by a distance;
a grass trimming head connected to said housing, wherein said grass trimming head comprises a base, a cap matched and connected to said base, and a spool arranged between said base and said cap; said spool has a first state static relative to said base;
a main motor driving said grass trimming head to rotate around an axis;
a main switch controlling said main motor;
a cord delivering mechanism, wherein said cord delivering mechanism comprises a control circuit electrically connected to said main motor, and said control circuit is used for controlling said main motor to be converted between a working speed and a cord delivering speed with said cord delivering speed being different than said working speed;
said control circuit comprising a cord delivering electronic switch independent of said main switch, said cord delivering electronic switch operably electrically controls said control circuit to enable said spool to be in a second state capable of generating a rotary speed difference relative to said base.

2. The grass trimmer according to claim 1 , wherein said cord delivering speed is smaller than working speed.

3. The grass trimmer according to claim 1 , wherein when said cord delivering electronic switch is started, said main motor is in a short circuit state.

4. The grass trimmer according to claim 1 , wherein a sliding block is arranged between said base and said spool, said sliding block is circumferentially fixed with said base to be radially movably matched and connected;
and said cord delivering mechanism further comprising a stopping device movably arranged at said base,
wherein said stopping device has a first position and a second position, when said stopping device is in said first position, said stopping device limits said sliding block from radially moving relative to said base, and when the stopping device is in said second position, said sliding bock can radially move relative to said base.

5. The grass trimmer according to claim 4 , wherein said stopping device comprises a stopping part arranged at said base in a pivoting manner, when in said first position, said stopping part stops said sliding block, and when in said second position, said stopping part is separated from said sliding block.

6. The grass trimmer according to claim 5 , wherein when said cord delivering electronic switch is started, said stopping part pivots to said second position from said first position relative to said base under the action of an inertia force.

7. The grass trimmer according to claim 6 , wherein when said cord delivering electronic switch is released, said stopping part pivots to said first position from said second position.

8. The grass trimmer according to claim 5 , wherein said stopping device comprises a reset device arranged between said stopping part and said base and prompts the stopping part to recover to said first position from said second position.

9. The grass trimmer according to claim 5 , wherein a pivoting axis of said stopping part and a rotary axis of said base are overlapped.

10. The grass trimmer according to claim 5 , wherein when said main switch is started up, said stopping part is in a first position limiting said sliding block from radially moving to said base.

11. The grass trimmer according to claim 1 , wherein said cord delivering electronic switch is a single-pole double-throw switch, said single-pole double-throw switch can be optionally in a first switching on position and a second switching on position,
said main switch is started up, said spool and said base synchronously rotate, and then the single-pole double-throw switch is in the first switching on position;
the single-pole double-throw switch is started up and is converted to the second switching on position from the first switching on position to generate a speed difference between said spool and said base;
and said single-pole double-throw switch is released and recovers to the first switching on position from the second switching on position to generate a speed difference between said spool and said base, and after preset time, said spool and said base recover synchronous rotating.

12. A cord delivering method for a grass trimmer, comprising an extending rod extending longitudinally; a housing arranged at one end of said extending rod; a handle arranged on said extending rod and spaced from said housing by a distance; a grass trimming head connected to said housing, wherein said grass trimming head comprises a base, a cap matched and connected to said base, and a spool arranged between said base and said cap; said spool has a first state static relative to said base; a main motor driving said grass trimming head to rotate around an axis; a main switch controlling said main motor; a cord delivering mechanism, wherein said cord delivering mechanism comprises a control circuit electrically connected to said main motor, and said control circuit is used for controlling said main motor to be converted between a working speed and a cord delivering speed; said control circuit comprising a cord delivering electronic switch independent of said main switch, said cord delivering electronic switch operably electrically controls said control circuit to enable said spool to be in a second state capable of generating a rotary speed difference relative to said base, wherein the cord delivering method comprises the operation step of:
starting up said cord delivering electronic switch to generate a speed difference between said spool and said base with said cord delivering speed being different than said working speed.

13. The cord delivering method for a grass trimmer according to claim 12 , wherein the operation step further comprises a step of: releasing said cord delivering electronic switch.

14. The cord delivering method for a grass trimmer according to claim 12 , wherein before starting said cord delivering electronic switch, starting up said main switch to drive said main motor to drive said base and said spool to synchronously rotate.

15. The cord delivering method for a grass trimmer according to claim 13 , wherein before starting said cord delivering electronic switch, starting up said main switch to drive said main motor to drive said base and said spool to synchronously rotate.

Assignees

• Positec Power Tools Suzhou Co Ltd

Inventors

• Ma Yichun
• Zhang Shisong
• Mou Guoliang
• Zhong Hongfeng
• Liu Fangshi
• Pang Xiaoli
• Baker Robert
• Martin Brandon

Classifications

• A01D34/4161 Primary

  Means for feeding cutter line · CPC title

• A01D34/4163

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

• A01D34/416

  Flexible line cutters · CPC title