Power module for a brushless motor

Patent metadata

Field	Value
Publication number	US-11418089-B2
Application number	US-202016871349-A
Country	US
Kind code	B2
Filing date	May 11, 2020
Priority date	Dec 18, 2014
Publication date	Aug 16, 2022
Grant date	Aug 16, 2022

Abstract

A power tool is provided, including a housing; an electric brushless DC motor disposed within the housing; and a power module disposed within the housing and electrically coupled to the motor. The power module includes a circuit board, a first set of power switches mounted on a first surface of the circuit board, a second set of power switches mounted on a second surface of the circuit board substantially opposite the first set of power switches and electrically coupled to the first set of power switches forming an inverter bridge circuit, power terminals arranged on a side edge of the circuit board and coupled to the output of the inverter bridge, a first heat sink mounted on the first surface of the circuit board covering the first set of power switches, and a second heat sink covering the first heat sink and at least portions of the power terminals.

First claim

The invention claimed is:

1. A power tool comprising:
a housing;
an electric brushless DC motor disposed within the housing; and
a power module disposed within the housing and electrically coupled to the motor, the power module comprising:
a circuit board;
a first plurality of power switches mounted on a first surface of the circuit board;
a second plurality of power switches mounted on a second surface of the circuit board substantially opposite the first plurality of power switches and electrically coupled to the first plurality of power switches forming an inverter bridge circuit;
a plurality of power terminals having main portions mounted on the first surface of the circuit board between a side edge of the circuit board and the first plurality of power switches and extension portions extending from the main portions away from the circuit board, the main portions being electrically coupled to the inverter bridge;
a first heat sink extending parallel to the circuit board and covering the first plurality of power switches but not the main portions of the plurality of power terminals; and
a second heat sink disposed over the first heat sink and covering the first heat sink and at least parts of the main portions of the plurality of power terminals.

2. The power tool of claim 1 , wherein the power module comprises a first plurality of discrete conductive tracks disposed on the first surface of the circuit board and spaced apart along an axis, and a first main conductive track disposed on the first surface of the circuit board forming an elongated gap between the first main conductive track and the first plurality of discrete conductive tracks on the circuit board parallel to the axis, wherein the main portions of the plurality of power terminals are mounted on the first plurality of discrete conductive tracks and the first plurality of power switches are electrically coupled between the first main conductive track and the first plurality of discrete conductive tracks.

3. The power tool of claim 2 , wherein the first heat sink comprises two legs mounted on and electrically coupled to the first main conductive track.

4. The power tool of claim 2 , wherein the power module further comprises a second main conductive track mounted on the second surface of the circuit board coupling first nodes of the second plurality of power switches together, and a second plurality of discrete conductive tracks disposed on the second surface of the circuit board substantially opposite the first plurality of discrete conductive tracks parallel to the axis electrically coupling second nodes of the second plurality of power switches to the plurality of power terminals.

5. The power tool of claim 4 , wherein the power module further comprises a plurality of through-holes through the circuit board between the first plurality of discrete conductive tracks and the second plurality of discrete conductive tracks near the side edge of the circuit board, the plurality of power terminals having legs received through the plurality of through-holes.

6. The power tool of claim 5 , wherein the plurality of through-holes comprises conductive vias electrically connecting the first plurality of discrete conductive tracks and the second plurality of discrete conductive tracks.

7. The power tool of claim 4 , wherein the first plurality of power switches comprises high-side field-effect transistors (FETs), the second plurality of power switches comprises low-side FETs.

8. The power tool of claim 4 , wherein the first main conductive track and the second main conductive track are respectively coupled to positive and negative terminals of a power source.

9. The power tool of claim 1 , wherein heat generated by the second plurality of power switches is substantially dissipated by the plurality of power terminals.

10. The power tool of claim 9 , wherein the plurality of power terminals together has a total surface metal area in the range of 100 to 200 mm2.

11. The power tool of claim 1 , wherein the tool comprises at least one of a finishing nailer, a framing nailer, or a concrete nailer.

12. The power tool of claim 11 , further comprising a driver assembly disposed within the housing along a longitudinal axis, wherein the motor is an outer-rotor motor having a flywheel that engages the driver assembly, and the power module is disposed adjacent the motor with the circuit board being arranged on a plane parallel the longitudinal axis and intersecting the motor.

13. The power tool of claim 1 , wherein the power module further comprises a controller electrically coupled to gates of the first plurality of power switches and gates of the second plurality of power switches.

14. The power tool of claim 1 , wherein the power module further comprises a potting boat in which the circuit boat is disposed, and potting material substantially covering both surfaces of the circuit board but leaving a surface of the heat sink exposed.

15. The power tool of claim 14 , wherein the second heat sink is secured to the potting boat via at least one fastener.

16. The power tool of claim 1 , wherein the power module further comprises a thermally-conductive thermally-isolating pad disposed over the first heat sink and at least a portion of the plurality of power terminals, and the second heat sink is disposed over the pad to be in thermal communication with the first heat sink and the plurality of power terminals but electrically isolated from the first heat sink and the plurality of power terminals.

17. The power tool of claim 1 , wherein the second heat sink has three to six times the total size of the first heat sink.

18. The power tool of claim 1 , wherein the second heat sink comprises a plurality of upwardly projecting fins.

19. The power tool of claim 1 , wherein the first heat sink does not cover any portion of the plurality of power terminals.

Assignees

• Black & Decker Inc

Inventors

• Purohit Madhur M
• Fogle John B
• Grove Michael D

Classifications

• H02K7/086

  radially supporting the rotor around a fixed spindle; radially supporting the rotor directly (H02K7/09 takes precedence) · CPC title

• H02K29/08 Primary

  using magnetic effect devices, e.g. Hall-plates, magneto-resistors (H02K29/12 takes precedence) · CPC title

• H02K11/215

  Magnetic effect devices, e.g. Hall-effect or magneto-resistive elements · CPC title

• B25F5/008

  Cooling means · CPC title

• H02K7/02

  Additional mass for increasing inertia, e.g. flywheels · CPC title