Dual-mode non-isolated corded system for transportable cordless power tools

• US 6,460,626 B2
• Filed: 07/24/2001
• Issued: 10/08/2002
• Est. Priority Date: 12/30/1998
• Status: Expired due to Fees

• Current Assignee: Black & Decker Incorporated (Stanley Black & Decker, Inc.)
• Original Assignee: Black & Decker Incorporated (Stanley Black & Decker, Inc.)
• Inventors: Carrier, David A.
• Primary Examiner(s): Smith, Scott A.
• Application Number:
  US09/911,985
• Publication Number:
  US 20010042631A1
• Time in Patent Office: 441 Days
• Field of Search: 173/1, 173/217, 173/171, 173/170, 310/47, 310/50
• US Class Current: 173/1
• CPC Class Codes: B25F 5/02 Construction of casings, bodies or handles B25F5/006, B25F5/008 take precedence
• CPC Class Codes: H01H 2009/065 Battery operated hand tools in which the battery and the switch are directly connected
• CPC Class Codes: H01H 9/06 Casing of switch constituted by a handle serving a purpose other than the actuation of the switch, e.g. by the handle of a vacuum cleaner
• CPC Class Codes: H01H 9/52 Cooling of switch parts cooling of contacts H01H1/62
• CPC Class Codes: H02H 7/0852 directly responsive to abnormal temperature by using a temperature sensor in a control circuit H02H7/0833
• CPC Class Codes: H02J 7/0044 specially adapted for holding portable devices containing batteries H02J7/0045 takes precedence
• CPC Class Codes: H02J 7/0068 Battery or charger load switching, e.g. concurrent charging and load supply H02J7/0013 takes precedence

Abstract

A dual-mode system for inexpensively operating electrically powered double-insulated devices (12), such as hand-held power tools and appliances. The system includes a cordless battery pack (14) that supplies the power and current demands of the device (12) in a cordless mode or a non-isolated corded voltage converter (16) that supplies the necessary power and current demands in a physical envelope commensurate in size and interchangeable with that of the battery pack (14). The corded voltage converter (16) is provided with a non-isolated high efficiency power supply that allows the converter (16) to generate the power and current required by the driven device (12). The double insulation of the driven device (12) negates the need for a transformer-isolated voltage converter. Eliminating the power transformer from the converter significantly reduces the cost of the module (16). Additionally, the need for multiple battery packs and fast rechargers is minimized by the availability of a low-cost converter. The voltage converter (16) includes an inrush current limiter (103) and power conditioner for filtering AC or DC input power. The filtered voltage is chopped by a transformerless buck-derived converter. The chopped voltage is rectified and filtered to provide low-voltage DC power to the drive motor of the powered double-insulated device (12).

Claims

1. A corded/cordless system for power tools comprising:

a low-voltage DC power tool operable in a preselected voltage range, said power tool having an exterior, an interior, a pre-defined interface for mechanically and electrically mating with a power supply module, and a double-insulated case to prevent the conduction of electrical charge from the interior to the exterior of the power tool; and

a corded non-isolated power supply module mechanically and electrically configured to connect to a source of relatively high voltage electric power and to mate with the low-voltage DC power tool, said corded non-isolated power supply module being adapted to convert said relatively high voltage line power from the source of electric power to a DC voltage in the preselected voltage range suitable for powering the low-voltage DC power tool.

2. The corded/cordless system of claim 1 further comprising:

a cordless battery power supply module mechanically and electrically configured to mate with the low-voltage DC power tool and to contain a battery assembly having a DC voltage in the preselected voltage range suitable for powering the low-voltage DC power tool, said battery power supply module to provide power from the battery assembly to the DC power tool;

wherein the power tool is configured to receive power from either the corded non-isolated power supply module or the battery power supply module.

3. The corded/cordless system of claim 2 wherein the power tool pre-defined interface further comprises a physical envelope configuration to accept either of said corded non-isolated power supply module and said cordless battery power supply module.

4. The corded/cordless system of claim 3 wherein the power tool pre-defined interface further comprises an electrical connector operative to electrically connect to an electrical connector attached to either of said corded non-isolated power supply module and said cordless battery power supply module.

5. The corded/cordless system of claim 4 wherein the corded non-isolated power supply module electrical connector is a terminal block and the battery power supply module electrical connector is a terminal block.

6. The corded/cordless system of claim 3 wherein the power tool pre-defined interface further comprises a latch for releasably securing either of said corded non-isolated power supply module and said cordless battery power supply module.

7. The corded/cordless system of claim 1 wherein the power tool includes a motor.

8. The corded/cordless system of claim 1 wherein the corded non-isolated power supply module comprises:

a circuit to convert power from the source of relatively high voltage electric power to the DC voltage in the pre-selected voltage range, wherein the DC voltage is referenced to the power from the source of relatively high voltage electric power.

9. The corded/cordless system of claim 8 wherein the source of relatively high voltage electric power provides approximately 120 Vac, 60 Hz power.

10. A corded/cordless system for power tools comprising:

a low-voltage DC power tool operable in a preselected voltage range, said power tool having an exterior, an interior, a double-insulated case to prevent the conduction of electrical charge from the interior to the exterior of the power tool, and a pre-defined interface for mechanically and electrically mating with a power supply module;

said power tool pre-defined interface comprising;

a physical envelope configuration to accept the power supply module;

a terminal block operative to electrically connect to a terminal block attached to the power supply module; and

a latch for releasably securing the power supply module;

a corded non-isolated power supply module mechanically and electrically configured to connect to a source of relatively high voltage electric power and to mate with the low-voltage DC power tool, said corded non-isolated power supply module including a circuit to convert power from the source of relatively high voltage electric power to a DC voltage in the pre-selected voltage range suitable for powering the low-voltage DC power tool, wherein the DC voltage is referenced to the power from the source of relatively high voltage electric power;

a cordless battery power supply module mechanically and electrically configured to mate with the low-voltage DC power tool and to contain a battery assembly having a DC voltage in the preselected voltage range suitable for powering the low-voltage DC power tool, said battery power supply module to provide power from the battery assembly to the DC power tool; and

wherein the power tool is configured to receive power from either the corded non-isolated power supply module or the battery power supply module.

11. A method of supplying power to a DC power tool operable in a preselected voltage range, said power tool having exposed surfaces, the method comprising the steps of:

insulating the exposed surfaces of the DC power tool to prevent the surfaces from becoming electrically energized;

connecting a corded non-isolated power supply module to the power tool and to a source of relatively high voltage electric power;

converting power from the source of relatively high voltage electric power to a DC voltage that is not transformer isolated from the source of relatively high voltage electric power, wherein said DC voltage is within the pre-selected voltage range suitable for powering the DC power tool; and

powering the DC power tool with the DC voltage.

12. A DC low voltage power tool operable in a preselected voltage range comprising:

an electrical system for operating the tool;

a pre-defined electrical interface for mechanically and electrically mating with a power supply module to energize the electrical system; and

a double insulated tool casing enclosing the electrical system to prevent the conduction of electrical charge from the interior to the exterior of the power tool.