Hedge trimmer with a dual gear setting

Patent metadata

Field	Value
Publication number	US-11185015-B2
Application number	US-201515776555-A
Country	US
Kind code	B2
Filing date	Nov 18, 2015
Priority date	Nov 18, 2015
Publication date	Nov 30, 2021
Grant date	Nov 30, 2021

Abstract

A hedge trimmer comprises: a drive motor (30, 130) disposed in a casing (21, 121); a gear mechanism disposed in the casing (21, 121) and connected to the drive motor (30, 130); and a blade arrangement having at least one cutter bar (20, 120). The at least one cutter bar (20, 120) is driven in a reciprocating manner in a longitudinal direction of the blade arrangement by the drive motor (30, 130) via the gear mechanism. The gear mechanism contains at least a first gear setting and a second gear setting producing two different gear-ratios, such that the at least one cutter bar (20, 120) is adapted to be driven at a first speed and torque using the first gear setting, and a second speed and torque different from the first speed and torque using the second gear setting. By providing two different trimming output modes, the hedge trimmer may provide either a high-speed/small-torque trimming capability or a low-speed/large-torque trimming capability to accommodate requirements under different operation circumstances.

First claim

The invention claimed is:

1. A hedge trimmer, comprising:
a) a drive motor disposed in a casing and defining an axis of rotation;
b) a gear mechanism disposed in the casing and connected to the drive motor, the gear mechanism comprising a planetary gear module and an output shaft, the output shaft defining an axis of rotation offset from the axis of rotation of the drive motor;
c) a blade arrangement having at least one cutter bar, wherein the at least one cutter bar is driven in a reciprocating manner in a longitudinal direction of the blade arrangement by the drive motor via the gear mechanism;
wherein, the gear mechanism comprising at least a first gear setting and a second gear setting producing two different gear-ratios at the output shaft, the first gear setting having a larger diameter than the second gear setting, the first gear setting and the second gear setting being connected together and driven by a motor shaft of the drive motor, such that the at least one cutter bar is adapted to be driven continuously at a first speed and torque using the first gear setting below a predetermined threshold of a torque received from the at least one cutter bar in response to continued engagement of a trigger, and continuously at a second speed and torque different from the first speed using the second gear setting at or above the predetermined threshold of the torque received from the at least one cutter bar in response to continued engagement of the trigger, and
wherein the planetary gear module is a part of at least one of the first gear setting and the second gear setting.

2. The hedge trimmer according to claim 1 , wherein the second gear setting comprises the planetary gear module, which at its input is connected to the drive motor and at its output is connected to the output shaft via a one-directional clutch; the first gear setting comprising a friction clutch connected between the drive motor and the output shaft.

3. The hedge trimmer according to claim 2 , wherein the friction clutch or the planetary gear module is connected to the drive motor via a gear shaft; the gear shaft having a first portion and a second portion along an axial direction of the gear shaft, with a number of teeth on the first portion different from that on the second portion.

4. The hedge trimmer according to claim 3 , wherein the number of teeth on the first portion of the gear shaft is larger than that on the second portion; the first portion engaging the motor shaft of the drive motor; the second portion engaging the friction clutch or the planetary gear module.

5. The hedge trimmer according to claim 2 , wherein the friction clutch is friction disc set.

6. The hedge trimmer according to claim 5 , wherein the friction disc set comprises two friction discs arranged concentrically;
between the friction discs a clamp gear configured of which two end faces contacting the two friction discs respectively;
the clamp gear engaging the drive motor; the friction discs rotatably connected to a friction hub which is adapted to drive the output shaft; and
wherein when a frictional force between the clamp gear and the friction discs is larger than a threshold, the clamping gear rotatably engaging the friction discs to transmit driving force to the output shaft;
when the frictional force between the clamp gear and the friction discs is smaller than a threshold, the clamping gear rotating relative to the friction discs such that no driving force is transmitted from the clamp gear to the friction discs.

7. The hedge trimmer according to claim 6 , wherein the two friction discs and the clamp disc are kept in contact in a sandwiched way by a spring.

8. The hedge trimmer according to claim 2 , wherein the one-directional clutch is a one-directional bearing.

9. The hedge trimmer according to claim 2 , wherein the one-directional clutch is configured such that when an output speed of the planetary gear module is smaller than the rotating speed of the output shaft, the output shaft adapted to freewheel with respect to the planetary gear module;
when an output speed of the planetary gear module is larger than the rotating speed of the output shaft, the planetary gear module transmitting a driving force to the output shaft.

10. The hedge trimmer according to claim 1 , wherein the drive motor is a brushless motor;
the hedge trimmer further comprising a motor controller connected to the drive motor;
the motor controller configured with a built-in motor overload protection.

11. The hedge trimmer according to claim 1 , wherein the drive motor is a brushed motor;
the hedge trimmer further comprising a battery pack in which a controller inside the battery pack is provided, so that the controller cuts off the battery power supply to the hedge trimmer if the drawn current from the battery goes over a predetermined limit.

12. A hedge trimmer, comprising:
a drive motor disposed in a casing and defining an axis of rotation;
a gear mechanism disposed in the casing and connected to the drive motor, the gear mechanism comprising a planetary gear module and an output shaft;
a blade arrangement having a cutter bar, wherein the cutter bar is driven in a reciprocating manner in a longitudinal direction of the blade arrangement by the drive motor via the gear mechanism;
wherein, the gear mechanism comprising at least a first gear setting and a second gear setting producing two different gear-ratios at the output shaft automatically according to a torque received from the cutter bar, the first gear setting having a larger diameter than the second gear setting, the first gear setting and the second gear setting being connected together and driven by a motor shaft of the drive motor, such that the a cutter bar is adapted to be driven continuously at a first speed and torque using the first gear setting below a predetermined threshold of the torque received from the cutter bar in response to continued engagement of a trigger, and continuously at a second speed and torque different from the first speed using the second gear setting at or above the predetermined threshold of the torque received from the cutter bar in response to continued engagement of the trigger,
wherein the second gear setting comprises the planetary gear module,
wherein the planetary gear module comprises an input, an output, and a one-directional clutch, the input of the planetary gear module being connected to the drive motor to receive rotational force therefrom, and the output of the planetary gear module being connected to the output shaft via the one-directional clutch to transmit rotational force therefrom,
wherein the first gear setting comprises the friction clutch connected between the drive motor and the output shaft to receive rotational force from the drive motor and transmit rotational force to the output shaft,
wherein the friction clutch or the planetary gear module is connected to the drive motor via a gear shaft; the gear shaft having a first portion and a second portion along an axial direction of the gear shaft, and
wherein the number of teeth on the first portion of the gear shaft is larger than that on the second portion; the first portion engaging the motor shaft of the drive motor; the second portion engaging the friction clutch or the planetary gear module.

13. The hedge trimmer according to claim 12 , wherein the friction clutch is friction disc set.

14. The hedge trimmer according to claim 13 , wherein the friction disc set comprises two friction discs arranged concentrically;
between the friction discs a clamp gear configured of which two end faces contacting the two friction discs respec

Assignees

• Tti Macao Commercial Offshore Ltd
• Techtronic Cordless Gp

Inventors

• Chung Koon For
• Wang Danny
• Xie Tim
• Rickey Todd

Classifications

• F16H2200/2033

  with one engaging means · CPC title

• F16H2200/2082

  one freewheel mechanisms · CPC title

• H02K7/116

  with gears · CPC title

• F16H21/18

  Crank gearings; Eccentric gearings · CPC title

• H02K7/108

  with friction clutches · CPC title