Grass Trimmer and Cord Delivering Method of Grass Trimmer

Patent metadata

Field	Value
Publication number	US-2019261557-A1
Application number	US-201916408991-A
Country	US
Kind code	A1
Filing date	May 10, 2019
Priority date	May 16, 2014
Publication date	Aug 29, 2019
Grant date	—

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 the extending rod, a handle arranged on the extending rod and spaced from the housing by a distance, a grass trimming head connected to the housing, a main motor driving the grass trimming head to rotate around an axis, and a main switch controlling the main motor, the grass trimming head comprising an accommodating base, a cap matched and connected to the accommodating base, and a spool arranged between the accommodating base and the cap, and the spool having a first state static relative to the accommodating base, wherein 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, 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 relative to the accommodating base, the control device comprises a control circuit electrically connected to the main motor, and the control circuit is used for controlling the main motor to be converted between a working speed and a cord delivering speed, and the working speed is different from the cord delivering speed.

2 . The grass trimmer according to claim 1 , wherein when the main switch is started up, the control circuit controls the main motor to be at a working speed, to enable the spool to be in the first state; and when the main switch is started up and the cord delivering electronic switch is started up, the control circuit controls the main motor to be converted from the working speed to the cord delivering speed, to enable the spool to be in the second state, and the cord delivering electronic switch is released to convert the main motor from the cord delivering speed back to the working speed.

3 . The grass trimmer according to claim 1 , wherein when the main switch is started up, the control circuit controls the main motor to be at a working speed, to enable the spool to be in the first state; and when the main switch is started up and the cord delivering electronic switch is started up, the control circuit controls the main motor to be converted from the working speed to the cord delivering speed, to enable the spool to be in the second state, and after the cord delivering speed is kept for preset duration, the control circuit controls the main motor to be converted from the cord delivering speed back to the working speed.

4 . The grass trimmer according to claim 3 , wherein the preset duration of keeping the cord delivering speed is 0.2 s to 2 s.

5 . The grass trimmer according to claim 1 , wherein when the main switch is started up and the cord delivering electronic switch is started up, the control circuit controls the main motor to short circuit.

6 . The grass trimmer according to claim 1 , wherein when the main switch is started up and the cord delivering electronic switch is started up, the control circuit controls an operating speed of the main motor to decrease to zero.

7 . The grass trimmer according to claim 1 , wherein the cord delivering speed is less than the working speed.

8 . The grass trimmer according to claim 7 , wherein the cord delivering speed is less than 3500 r/min.

9 . The grass trimmer according to claim 7 , wherein the cord delivering speed is zero.

10 . The grass trimmer according to claim 2 , wherein a time during which the control device controls the main motor to be converted from the working speed to the cord delivering speed is less than 1 second.

11 . The grass trimmer according to claim 3 , wherein a time during which the control device controls the main motor to be converted from the working speed to the cord delivering speed is less than 1 second.

12 . The grass trimmer according to claim 2 , wherein a time during which the control device controls the main motor to be converted from the cord delivering speed back to the working speed is less than 1 second.

13 . The grass trimmer according to claim 3 , wherein a time during which the control device controls the main motor to be converted from the cord delivering speed back to the working speed is less than 1 second.

14 . The grass trimmer according to claim 1 , wherein the cord delivering speed is greater than the working speed.

15 . The grass trimmer according to claim 14 , wherein a range of a working rotary speed of the main motor is 5000 r/min to 10000 r/min, and a set range of the cord delivering speed is 11000 r/min to 15000 r/min.

16 . The grass trimmer according to claim 1 , wherein the control circuit is a PWM modulation circuit.

17 . The grass trimmer according to claim 1 , wherein the cord delivering electronic switch is a single-pole double-throw switch, the single-pole double-throw switch is selectively in a first switching on position and a second switching on position, the main switch is started up, the spool and the accommodating 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 the spool and the accommodating base; and the 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 the spool and the accommodating base, and after preset time, the spool and the accommodating base recover synchronous rotating.

18 . A cord delivering method for the grass trimmer according to claim 1 , the cord delivering method comprising the following operation steps: starting up a main switch to enable a spool and an accommodating base to synchronously rotate; and starting up a cord delivering electronic switch to generate a speed difference between the spool and the accommodating base.

19 . A cord delivering method for the grass trimmer according to claim 17 , the cord delivering method comprising the following operation steps: starting up a main switch to enable a spool and an accommodating base to synchronously rotate; and starting up a cord delivering electronic switch to generate a speed difference between the spool and the accommodating base.

20 . The cord delivering method for the grass trimmer according to claim 18 , wherein the operation steps further comprise: releasing the cord delivering electronic switch.

21 . A cord delivering method for the grass trimmer according to claim 1 , the cord delivering method comprising the following operation steps: starting up a main switch to enable a spool and an accommodating base to synchronously rotate; and starting up a cord delivering electronic switch to generate a speed difference between the spool and the accommodating base, wherein after preset time, the spool and the accommodating base recover synchronous rotating.

22 . A cord delivering method for the grass trimmer according to claim 17 , the cord delivering method comprising the following operation steps: starting up a main switch to enable a spool and an accommodating base to synchronously rotate; and starting up a cord delivering electronic switch to generate a speed difference between the spool and the accommodating base, wherein after preset time, the spool and the accommodating base recover s

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

• A01D34/4163

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

• A01D34/416

  Flexible line cutters · CPC title

• A01D34/4161 Primary

  Means for feeding cutter line · CPC title