Brushless dc motor power tool with combined pcb design

Patent metadata

Field	Value
Publication number	US-2016359392-A1
Application number	US-201615241475-A
Country	US
Kind code	A1
Filing date	Aug 19, 2016
Priority date	May 24, 2012
Publication date	Dec 8, 2016
Grant date	—

Abstract

A power tool with a combined printed circuit board (PCB) that reduces internal wiring of the power tool and provides a large amount of air flow to internal components. In some instances, the combined PCB has a surfboard shape and includes a motor control unit and power switching elements (Field Effect Transistors or FETs). The combined surfboard PCB is located above the trigger, but below the motor and drive mechanism. In other instances, the combined PCB has a doughnut shape and is located coaxially with a motor shaft. The combined PCB may be positioned between a doughnut-shaped control PCB and the motor.

First claim

What is claimed is:

1 . A power tool comprising:
a housing; a brushless direct current (DC) motor within the housing and having a rotor and a stator, wherein the rotor is coupled to a motor shaft to produce a rotational output; an output unit coupled to the motor shaft to provide the rotational output outside of the housing; a first printed circuit board (PCB) having a Hall sensor and a through-hole through which the motor shaft extends, wherein the first PCB includes motor lead pads each having a peripheral opening that receives a motor lead wire from the stator; power switching elements to drive the brushless DC motor; and a second PCB having a motor control unit that receives motor positional information from the Hall sensor and controls the power switching elements to drive the brushless DC motor.

2 . The power tool of claim 1 , wherein the motor lead wires are soldered to the motor lead pads.

3 . The power tool of claim 1 , wherein the first PCB includes the power switching elements.

4 . The power tool of claim 1 , further comprising a heat sink secured to an end of the brushless DC motor, wherein the first PCB is coupled to the heat sink.

5 . The power tool of claim 4 , wherein the heat sink has a second through-hole through which the motor shaft extends.

6 . The power tool of claim 4 , further comprising a fan positioned at a rear end opposite the end of the brushless DC motor to which the heat sink is secured, wherein the fan is rotatable by the brushless DC motor to generate a cooling air flow within the housing of the power tool.

7 . The power tool of claim 1 , further comprising an end cap coupled to an end of the brushless DC motor, wherein the end cap includes wire supports each receiving one of the motor lead wires from the stator.

8 . The power tool of claim 7 , wherein the wire supports guide the motor lead wires radially outward to the motor lead pads, respectively.

9 . A power tool comprising:
a housing; a brushless direct current (DC) motor within the housing and having a rotor and a stator, wherein the rotor is coupled to a motor shaft to produce a rotational output; an end cap coupled to an end of the stator, wherein the end cap includes wire supports that each receive a motor lead wire from the stator; an output unit coupled to the motor shaft to provide the rotational output outside of the housing; a first printed circuit board (PCB) having a Hall sensor, a through-hole through which the motor shaft extends, and motor lead pads, wherein the wire supports guide the motor lead wires radially outward to the motor lead pads, respectively; power switching elements to drive the brushless DC motor; and a second PCB having a motor control unit that receives motor positional information from the Hall sensor and controls the power switching elements to drive the brushless DC motor.

10 . The power tool of claim 9 , wherein each of the motor lead wires is soldered to a respective one of the motor lead pads.

11 . The power tool of claim 9 , wherein the first PCB includes the power switching elements.

12 . The power tool of claim 9 , wherein a heat sink is positioned between brushless DC motor and the first PCB, and wherein the heat sink has a second through-hole through which the motor shaft extends.

13 . The power tool of claim 12 , further comprising a fan positioned at a rear end opposite the end of the stator where the end cap is coupled, wherein the fan is rotatable by the brushless DC motor to generate a cooling air flow within the housing.

14 . The power tool of claim 9 , wherein each of the wire supports is aligned with a respective one of the motor lead pads.

15 . The power tool of claim 9 , wherein the second PCB is located in one of
a terminal block portion of the tool below a handle portion of the tool, the handle portion, and a location above a trigger of the power tool and below the brushless DC motor.

16 . The power tool of claim 9 , wherein the power tool is one of a hammer drill/driver, a drill/driver, an impact driver, and an impact wrench.

17 . The power tool of claim 9 , wherein the wire supports are located on an outside of a periphery of the end cap.

18 . The power tool of claim 9 , wherein the end cap includes second wire supports located radially inward of the wire supports, wherein the second wire supports each receive one of the motor lead wires.

19 . A method of coupling a printed circuit board (PCB) to a motor having a rotor and a stator, the method comprising:
placing an end cap on an end of the motor, the end cap having a wire support that receives a motor lead wire from the stator; placing a heat sink on the end cap such that the end cap is located between the heat sink and the motor; bending the motor lead wire such that the motor lead wire is received in the wire support; placing a heat sink pad on the heat sink; placing a PCB on the heat sink pad, the PCB having a Hall sensor, power switching elements, and a through-hole; and soldering the motor lead wire to the PCB.

20 . The method of claim 19 , wherein placing the heat sink on the end cap includes placing the heat sink on the end cap such that
a portion of the heat sink is located in a recess between the wire support and a second wire support; and the wire support and the second wire support extend in an axial direction past the heat sink and receive the motor lead wire.

Assignees

• Milwaukee Electric Tool Corp

Inventors

• Mergener Matthew J
• Kolden Michael
• Check William E
• Wycklendt Matthew P
• Beyerl Andrew T

Classifications

• H02K11/33

  Drive circuits, e.g. power electronics (H02K11/38 takes precedence) · CPC title

• H02K9/06

  with fans or impellers driven by the machine shaft · CPC title

• H02K21/046

  with rotating permanent magnets and stationary field winding · CPC title

• B25F5/008

  Cooling means · CPC title

• H02K7/145 Primary

  Hand-held machine tool · CPC title