Portable motor powered device

• US 20030127932A1
• Filed: 02/14/2003
• Published: 07/10/2003
• Est. Priority Date: 07/02/1999
• Status: Active Grant

• Current Assignee: Panasonic Electric Works Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Atsumasa Kubota, Hiroshi Miyazaki, Kazuto Toyama, Koichi Hashimoto, Masao Yamamoto, Tomio Yamada, Toru Murakita, Yosuke Ishida
• Inventors: Murakita, Toru, Yamamoto, Masao, Yamada, Tomio, Hashimoto, Koichi, Miyazaki, Hiroshi, Toyama, Kazuto, Kubota, Atsumasa, Ishida, Yosuke
• Granted Patent: US 6,683,396 B2
• Time in Patent Office: Days
• US Class Current: 310/184
• CPC Class Codes: B25F 5/00 Details or components of portable power-driven tools not particularly related to the operations performed and not otherwise provided for
• CPC Class Codes: H02K 23/36 having two or more windings; having two or more commutators; having two or more stators

Abstract

A portable motor powered device capable of operating on a cordless battery pack as well as a corded power pack, yet enabling to reduce the size and weight of the corded power pack to be truly compatible with the corded battery pack in size and weight. The device has a housing accommodating therein a DC motor as a power source. The cordless battery pack is detachably connected to the housing and has a battery which supplies a low DC voltage for operating the DC motor. The corded power pack is detachably connected to the housing and supplies a high DC voltage for operating the DC motor. The corded power pack includes a power cord adapted to be connected to receive an AC source voltage and a converter for converting the AC source voltage into the high DC voltage. The DC motor has a rotor provided with first and second windings which are selectively connected to receive low and high DC voltages respectively from the cordless battery pack and the corded power pack. Thus, the corded power pack can be designed to supply the high DC voltage directly converted from the AC voltage source and therefore dispense with a step-down transformer of bulky and heavy nature.

Claims

1. A portable motor powered device comprising:

a housing accommodating a DC motor which operates selectively at two different DC voltages;

a cordless battery pack detachably connected to said housing and having a battery which supplies a low DC voltage for operating said DC motor;

a corded power pack detachably connected to said housing and supplying a high DC voltage for operating said motor, said corded power pack having a power cord adapted to be connected to receive an AC source voltage and a converter for converting said AC source voltage into said high DC voltage;

wherein

said DC motor includes a rotor provided with a first winding and a second winding, said first winding being coupled to receive said low voltage for driving said DC motor, and said second winding being coupled to receive said high voltage for driving said DC motor.

2. The portable motor powered device as set forth in claim 1, wherein said first and second windings are designed to give the same torque-speed characteristic to said DC motor when operated at said low DC voltage and at said high DC voltage, respectively.

3. The portable motor powered device as set forth in claim 1, wherein said housing includes a first electrical path connecting said low DC voltage to said first winding, and a second electrical path connecting said high DC voltage to said second winding, said first and second electrical paths being separated from each other.

4. The portable motor powered device as set forth in claim 1, wherein said first winding is designed to operate on said low DC voltage of 2.4 to 48 volts, while said second winding is designed to operate on said high DC voltage of 100 to 300 volts.

5. The portable motor powered device as set forth in claim 1, wherein said cordless battery pack and said corded power pack have respective casings of similar shape which are selectively attached to said housing.

6. The portable motor powered device as set forth in claim 5, wherein the casing of said cordless battery pack includes a first plug for insertion into a socket of said housing, and the casing of said corded power pack includes a second plug for insertion into said socket, said first plug having a low voltage contact for electrical connection with a first terminal provided in said socket, and said second plug having a high voltage connector for electrical connection with a second terminal provided in said socket.

7. The portable motor powered device as set forth in claim 6, wherein said corded power pack has a ground lead extending therefrom for connection to the ground, said second connector including a ground terminal for electrical connection between said motor and said ground lead.

8. The portable motor powered device as set forth in claim 7, wherein said corded power pack includes a circuit board on which said converter is mounted, said circuit board including a ground line for connection between said ground terminal and said ground lead, said ground line being connected to a noise reduction capacitor on said printed circuit board.

9. The portable motor powered device as set forth in claim 1, wherein said corded power pack has a casing to which one end of said power cord is supported to pivot about a pivot axis.

10. The portable motor powered device as set forth in claim 9, wherein said corded power pack includes a click mechanism for retaining said power cord at least one angular position around said pivot axis.

11. The portable motor powered device as set forth in claim 1, further including:

a speed sensor which is connectable to non-energized one of said first and second windings to detect an alternating voltage developed across said non-energized one of said first and second windings for sensing a rotation speed of said motor while the other one of said first ands second windings is energized to drive said motor.

12. The portable motor powered device as set forth in claim 1, wherein 3, wherein

said housing includes a power switch for connecting said low and high DC voltages to said first and second windings, respectively,

said rotor including a core provided with said first and second windings and a rotor shaft extending through said core, said rotor shaft carrying first and second commutators respectively connected to said first and second windings, said first and second commutators being disposed on opposite sides of said core to be spaced axially along said rotor shaft and being in contact with first and second brushes which supply currents respectively from said low and high DC voltages,

said first bush being connected to said power switch through a low voltage line, said second brush being connected to said power switch through a high voltage line,

said low voltage line being routed within said housing a shorter path than said high voltage line.

13. The portable motor powered device as set forth in claim 12, wherein said rotor shaft carries a cooling fan which is disposed adjacent to said first brush.