Electric power tool

Patent metadata

Field	Value
Publication number	US-12068708-B2
Application number	US-201916726378-A
Country	US
Kind code	B2
Filing date	Dec 24, 2019
Priority date	Jan 10, 2019
Publication date	Aug 20, 2024
Grant date	Aug 20, 2024

Abstract

An electric power tool includes: a motor; a driving circuit configured to drive the motor to output motive power; a control module configured to control the driving circuit; an energy storage element connected to the driving circuit; a current limiting element connected in series with the energy storage element and configured to charge the energy storage element with a first current; a switching element electrically connected in series with the energy storage element, connected in parallel with the current limiting element, and configured to charge or discharge the energy storage element with a second current. The electric power tool can avoid the occurrence of adverse situations such as generating electric sparks at the connection terminals of the electric power tool and of a battery pack when the battery pack is inserted into the electric power tool.

First claim

What is claimed is:

1. An electric power tool, powered by a battery pack that is detachably mounted to the electric power tool, comprising:
a motor;
a driving circuit configured to drive the motor to output motive power;
a control module configured to control the driving circuit;
an energy storage element connected to the driving circuit;
a current limiting element, connected in series with the energy storage element, configured to charge the energy storage element with a first current; and
a switching element, electrically connected in series with the energy storage element and connected in parallel with the current limiting element all in parallel to the motor, configured to charge or discharge the energy storage element with a second current;
wherein a first end of the energy storage element is connected to a positive pole of a power bus that functions to couple the motor to the battery pack, a second end of the energy storage element is coupled to a first end of the switching element, and a second end of the switching element is coupled to a negative pole of the power bus.

2. The electric power tool of claim 1 , wherein the control module is configured to control the switching element to be turned on for making the current limiting element short-circuited after the energy storage element is charged with the first current through the current limiting element to reach a preset voltage threshold.

3. The electric power tool of claim 2 , wherein the preset voltage threshold is equal to or substantially equal to a voltage value of the battery pack.

4. The electric power tool of claim 1 , wherein the control module is configured to control the switching element to be turned on for making the current limiting element short-circuited after the energy storage element is charged with the first current through the current limiting element to reach a preset electric quantity threshold.

5. The electric power tool of claim 4 , wherein a ratio of the preset electric quantity threshold to a full electric quantity of the energy storage element ranges from 0.7 to 1.

6. The electric power tool of claim 1 , wherein the control module is configured to control the switching element to be turned on for making the current limiting element short-circuited after the energy storage element is charged with the first current through the current limiting element for a preset duration.

7. The electric power tool of claim 1 , wherein the switching element is a relay switch.

8. The electric power tool of claim 1 , wherein the switching element is a semiconductor switch.

9. The electric power tool of claim 1 , wherein the switching element is a field effect transistor.

10. The electric power tool of claim 1 , wherein a value of the first current ranges from 20 mA to 1500 mA.

11. The electric power tool of claim 1 , wherein the first current flows between the energy storage element and the battery pack and the second current flows between the energy storage element and the driving circuit.

12. The electric power tool of claim 1 , wherein the battery pack comprises a cell group, comprised of a plurality of electrically connected cells, a positive power supply terminal, connected to a positive electrode of the cell group, and a negative power supply terminal, connected to a negative electrode of the cell group.

13. The electric power tool of claim 12 , further comprising a positive connection terminal configured to be connected to the positive power supply terminal of the battery pack and a negative connection terminal configured to be connected to the negative power supply terminal of the battery pack, wherein the driving circuit has a first driving end connected to the positive connection terminal and a second driving end connected to the negative connection terminal, and wherein the energy storage element is connected to the first driving end or the second driving end.

14. The electric power tool of claim 1 , further comprising a trigger mechanism operatively triggered for starting the motor and a signal switch connected to the trigger mechanism configured to output a starting signal to the control module, wherein the control module is configured to output a first control signal to control the switching element to be turned on for making the current limiting element short-circuited after the starting signal outputted by the signal switch is received.

15. The electric power tool of claim 14 , wherein the control module is configured to output a second control signal to the driving circuit for making the motor rotate after the switching element is turned on.

16. The electric power tool of claim 1 , further comprising a first voltage detection circuit configured to detect a voltage across two ends of the energy storage element.

17. The electric power tool of claim 1 , further comprising a second voltage detection circuit configured to detect a voltage of the battery pack.

18. An electric power tool, powered by a battery pack that is detachably mounted to the electric power tool, comprising:
a motor;
a driving circuit configured to drive the motor to output motive power;
a control module configured to control the driving circuit;
an energy storage element connected to the driving circuit; and
a protection circuit electrically connected between the energy storage element and the driving circuit comprising a first circuit and a second circuit arranged in parallel and all in parallel to the motor;
wherein the first circuit is connected to the energy storage element and is configured to charge the energy storage element with a first current, the second circuit is connected to the energy storage element and is configured to charge or discharge the energy storage element with a second current, a first end of the energy storage element is connected to a positive pole of a power bus that functions to couple the motor to the battery pack, a second end of the energy storage element is coupled to a first end of the switching element, and a second end of the switching element is coupled to a negative pole of the power bus,
wherein the first circuit comprises a current limiting element connected in series with the energy storage element and the second circuit comprises a switching element electrically connected in series with the energy storage element and connected in parallel with the current limiting element.

19. The electric power tool of claim 18 , wherein the control module is configured to control the switching element to be turned on to make the current limiting element short-circuited after the energy storage element is charged with the first current through the current limiting element to meet a preset condition.

Assignees

• Nanjing Chervon Ind Co Ltd

Inventors

• Yang Dezhong
• Xian Chao
• Mei Qingxiao
• Yang Yuwei
• Xu Tianxiao

Classifications

• H02J7/865

  Battery or charger load switching, e.g. concurrent charging and load supply (H02J7/50 takes precedence) · CPC title

• H02J7/60

  including safety or protection arrangements · CPC title

• H02P27/06

  using DC to AC converters or inverters (H02P27/05 takes precedence) · CPC title

• H02P1/022

  Security devices, e.g. correct phase sequencing · CPC title

• H02P29/024 Primary

  Detecting a fault condition, e.g. short circuit, locked rotor, open circuit or loss of load · CPC title