Power tool with separate motor case compartment

Patent metadata

Field	Value
Publication number	US-10404136-B2
Application number	US-201615262069-A
Country	US
Kind code	B2
Filing date	Sep 12, 2016
Priority date	Oct 14, 2015
Publication date	Sep 3, 2019
Grant date	Sep 3, 2019

Abstract

A handheld grinder includes an elongated housing, an electric motor, an output shaft, a wall, a planar circuit board, and a motor drive circuit. The elongated housing defines a cavity therein and includes a motor case disposed at a front end and a handle portion to a rear end. The electric motor has a drive shaft that is mounted within the motor case. The output shaft is drivably coupled to the drive shaft of the electric motor. The wall separates the cavity between the motor case and the handle portion of the housing. The planar circuit board disposed in the handle portion of the housing. The motor drive circuit is accommodated entirely within the handle portion of the housing on the planar circuit board.

First claim

What is claimed is:

1. A power tool comprising:
a housing defining a cavity therein, where the housing includes a motor case portion and a non-motor case portion;
an electric motor having a drive shaft and mounted within the motor case portion of the housing;
a motor drive circuit accommodated within the non-motor case portion of the housing and configured to drive the electric motor;
a partition separating the motor case portion from the non-motor case portion of the housing, where the partition is in form of a pocket with an open end facing the motor case portion;
a rear bearing for the drive shaft, the rear bearing disposed into the open end of the pocket and supported by an inner surface of the pocket;
one or more sense magnets affixed to the drive shaft, where the one or more sense magnets are arranged along the drive shaft in between the rear bearing and a closed end of the pocket;
one or more position sensors mounted to a position sense board, where the position sensors cooperate with the one or more sense magnets to sense rotational motion of the drive shaft; and
a slot formed in the pocket and configured to radially receive the position sense board therein, such that the position sense board is arranged adjacent to the one or more sense magnets inside the pocket.

2. The power tool of claim 1 wherein the slot in the pocket is overmolded and thereby fluidly seals the position sense board in the pocket.

3. The power tool of claim 1 wherein the position sense board includes a mounting area which extends outside the slot and a plurality of wires are attached to the mounting area of the position sense board.

4. The power tool of claim 3 wherein the slot in the pocket is overmolded such that the overmold encases the mounting area of the position sense board.

5. The power tool of claim 4 wherein the position sense board includes an aperture to partially receive the shaft therein.

6. A power tool comprising:
a housing defining a cavity therein, where the housing includes a motor case portion and a non-motor case portion;
an electric motor having a drive shaft and mounted within the motor case portion of the housing;
a motor drive circuit accommodated within the non-motor case portion of the housing and configured to drive the electric motor;
a partition separating the motor case portion from the non-motor case portion of the housing, where the partition is in form of a pocket with an open end facing the motor case portion;
a rear bearing for the drive shaft, the rear bearing disposed into the open end of the pocket and supported by an inner surface of the pocket; and
one or more sense magnets affixed to the drive shaft, where the one or more sense magnets are arranged along the drive shaft in between the rear bearing and a closed end of the pocket,
wherein the motor drive circuit includes:
a rectifier configured to receive an alternating current from an alternating current (AC) power source and operable to convert the alternating current to a direct current supplied to a DC power bus;
a switching arrangement having a plurality of motor switches connected electrically between the rectifier and the electric motor, and operates to deliver the direct current from the rectifier to electric motor;
a link capacitor electrically coupled in parallel with the rectifier and electrically connected between the rectifier and the switching arrangement; and
an auxiliary switch path electrically coupled in parallel with the rectifier and electrically connected between the rectifier and the switching arrangement, wherein the auxiliary switch path includes an auxiliary capacitor in series with a switch, such that the capacitance of the auxiliary capacitor is more than capacitance of the link capacitor.

7. The power tool of claim 6 wherein the motor drive circuit further includes a switch control circuit configured to detect voltage of the DC power bus and to control state of the switch in accordance with magnitude of the detected voltage, such that state of the switch creates either a charging path for the auxiliary capacitor or a discharging path for the auxiliary capacitor.

8. The power tool of claim 6 further comprises
a power module support structure disposed in the handle portion of the housing and extending axially along the longitudinal axis of the housing, thereby dividing the handle portion into an upper section and a lower section; and
a circuit board mounted to the power module support structure, the circuit board having a top board segment integrally interconnected by a hinge section to a bottom board segment, where the top board segment is folded over top of the bottom board segment and the top board segment is affixed to a top surface of the power module support structure and the bottom board segment is affixed to a bottom surface of the power module support structure.

9. The power tool of claim 8 wherein the plurality of motor switches are mounted along two lateral side surfaces of the power module support structure and further includes a heat sink mounted to each of the two lateral side surfaces of the power module support structure, such that the heat sink is adjacent and thermally coupled to the plurality of motor switches.

10. The power tool of claim 8 wherein a microcontroller and the link capacitor are mounted to the top board segment and the auxiliary capacitor is mounted to the bottom board segment.

11. A power tool comprising:
an elongated housing defining a cavity therein, where the housing includes a motor case disposed at a front end thereof and a handle portion extending axially along a longitudinal axis of the housing from the motor case to a rear end of the housing;
an electric motor having a drive shaft and mounted within the motor case, wherein one or more sense magnets are affixed to the drive shaft;
an output shaft drivably coupled to the drive shaft of the electric motor and extending perpendicular to the drive shaft;
a wall separating the cavity between the motor case and the handle portion of the housing, wherein the wall is in form of a pocket with an open end facing the motor case portion and the pocket is sized to receive the electric motor;
one or more position sensors mounted to a position sense board, wherein the position sense board is positioned into a slot formed in the pocket, such that the one or more position sensors are adjacent to the one or more sense magnets and cooperate with the one or more sense magnets to sense rotational motion of the drive shaft; and
a motor drive circuit accommodated within the handle portion of the housing and configured to deliver a direct current from a DC power bus to the electric motor.

12. The power tool of claim 11 wherein the slot in the pocket is overmolded and thereby fluidly seals the position sense board in the pocket.

13. The power tool of claim 11 further comprises a cover attached to the pocket, such that the cover encloses the position sense board in the slot.

14. The power tool of claim 11 further comprises a cover attached to the pocket, such that the cover partially encloses the position sense board in the slot.

15. The power tool of claim 11 wherein the motor drive circuit further includes
a rectifier configured to receive an alternating current from an alternating current (AC) power source and operable to convert the alternating current to a direct current supplied to the DC power bus;
a switching arrangement having a plurality of motor switches connected electrically between the rectifier and the electric motor, and operates to deliver the direct current from the rectifier to the electric motor;

Assignees

• Black & Decker Inc

Inventors

• Oktavec Craig A
• Smith David J
• Crosby Colin C
• Velderman Matthew J
• Privett Jr Zollie W
• Pant Pradeep
• Christophersen Kyle J
• Nace Daniel F
• Stiles Iii James H
• Moreland Iv Floyd E

Classifications

• H02K9/06

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

• H02K7/116

  with gears · CPC title

• H02K5/161

  radially supporting the rotary shaft at both ends of the rotor (H02K5/165, H02K5/167, H02K5/173 take precedence) · CPC title

• H02K5/225

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

• H02K5/10

  with arrangements for protection from ingress, e.g. water or fingers · CPC title