Control unit for a power tool

Patent metadata

Field	Value
Publication number	US-9318932-B2
Application number	US-201113712200-A
Country	US
Kind code	B2
Filing date	Jun 14, 2011
Priority date	Jun 14, 2010
Publication date	Apr 19, 2016
Grant date	Apr 19, 2016

Abstract

A power tool includes a brushless DC motor housed inside an upper body of the tool housing and a control unit housed inside a handle of the housing, the control unit including a micro-controller mounted on a control circuit board, a power unit electronically coupled to the micro-controller and mounted on a power circuit board arranged substantially parallel the control circuit board inside the handle, and a heat sink in thermal contact with the power unit. An input unit may be mounted directly on the control circuit board. An upper portion of the heat sink extending towards the upper body of the housing may include a tab protruding underneath a fan assembly of the motor to transfer heat from the power unit to the airflow created by the fan.

First claim

The invention claimed is:

1. A power tool
comprising: a housing;
a brushless DC motor housed inside an upper body of the housing; and
a control unit housed inside a handle of the housing, the control unit comprising a micro-controller mounted on a control circuit board, a power unit electronically coupled to the micro-controller and mounted on a power circuit board arranged substantially parallel the control circuit board inside the handle, and a heat sink in thermal contact with the power unit.

2. The power tool of claim 1 , further comprising an input unit a portion of which is integrally mounted on the control circuit board.

3. The power tool of claim 2 , wherein the input unit comprises a main body attached to a forward/reverse switch and a variable-speed switch, the main body being mounted on a portion of the control circuit board.

4. The power tool of claim 3 , wherein main body comprises a potentiometer coupled to the variable-speed switch.

5. The power tool of claim 3 , wherein an outer wall of the main body comprises at least one snap for securing a connection of the input unit over the control circuit board and a plurality of pins for providing signals associated with on/off, variable-speed, and forward/reverse functionalities to the micro-controller.

6. The power tool of claim 2 , wherein the control circuit board is greater in length than the power circuit board to accommodate the mounting of the input unit on the control circuit board adjacent the power circuit board.

7. The power tool of claim 6 , wherein the control unit further comprises a bulk capacitor mounted on the control circuit board adjacent the power circuit board.

8. The power tool of claim 1 , wherein the power unit comprises at least two through-holes for directly mounting the heat sink over the power unit.

9. The power tool of claim 2 , wherein the control unit further comprises a potting boat containing the control circuit board and the power circuit board, the potting boat having a cut-out portion to facilitate mounting the input unit on the control circuit board.

10. The power tool of claim 9 , wherein the cut out portion of the potting board includes a groove and the input unit includes a tongue fittingly corresponding to the groove to form a labyrinth.

11. A power tool comprising: a housing;
a brushless DC motor housed inside an upper body of the housing, the motor comprising a stator assembly and a rotor assembly partially arranged pivotably inside the stator assembly, the rotor assembly including a rotor lamination stack, a rotor fixedly housed inside a center portion of the lamination stack to pivot therewith, and a motor fan fixedly attached to the rotor and arranged adjacent the stator assembly; and
a control unit housed inside a handle of the housing, the control unit comprising a micro-controller, a power unit coupled to the micro-controller, and a heat sink in thermal contact with the power unit, wherein an upper portion of the heat sink extending towards the upper body of the housing comprises a tab protruding underneath the motor fan to transfer heat from the power unit to the airflow created by the motor fan.

12. The power tool of claim 11 , wherein the tab comprises a plurality of grooves underneath the fan to increase the surface contact of the tab with the motor fan airflow.

13. The power tool of claim 11 , wherein the heat sink further comprising a second tab protruding near at least one slot in the housing accommodating an input unit.

14. The power tool of claim 11 , further comprising an input unit mounted on a control circuit board of the control unit, wherein the heat sink further comprises a protruded surface to bypass the input unit.

15. The power tool of claim 11 , wherein the control unit comprising a control circuit board for mounting the micro-controller and a power circuit board for mounting the power unit, the power circuit board arranged substantially parallel the control circuit board inside the handle.

Assignees

• Purohit Madhur M
• Ortt Earl M
• Ekstrom Erik
• Waikar Shailesh P
• Coates Marcell E
• Hatfield Eric E
• Black & Decker Inc

Inventors

• Purohit Madhur M
• Ortt Earl M
• Ekstrom Erik
• Waikar Shailesh P
• Coates Marcell E
• Hatfield Eric E

Classifications

• H02K11/215

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

• H02K3/28

  Layout of windings or of connections between windings (windings for pole-changing H02K17/06, H02K17/14, H02K19/12, H02K19/32) · CPC title

• H02K11/33

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

• H02K21/16

  having annular armature cores with salient poles (with homopolar co-operation H02K21/20) · CPC title

• H02K5/225

  Terminal boxes or connection arrangements (specially adapted for submersible motors H02K5/132) · CPC title