Rechargeable electric tool

• US 7,817,053 B2
• Filed: 12/27/2005
• Issued: 10/19/2010
• Est. Priority Date: 01/12/2005
• Status: Active Grant

• Current Assignee: Max Co Limited
• Original Assignee: Max Co Limited
• Inventors: Kusakari, Ichiro, Matsuoka, Atsushi, Nagaoka, Takahiro, Itagaki, Osamu
• Primary Examiner(s): Blount; Eric M
• Application Number:
  US11/795,032
• Publication Number:
  US 20080094236A1
• Time in Patent Office: 1,757 Days
• Field of Search: 340/636.15, 340/636.1, 324/76.11
• US Class Current: 340/636.15
• 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: E04G 21/122 Machines for joining reinforcing bars
• CPC Class Codes: E04G 21/123 Wire twisting tools bundling articles by twisting, e.g. wire B65B13/28; bundling rods, sticks, or like elongated objects with, e.g. wire B65B27/10; tying devices for hops, vines or trees with, e.g. wire A01G17/08
• CPC Class Codes: H01M 10/345 Gastight metal hydride accumulators
• CPC Class Codes: H01M 10/44 Methods for charging or discharging circuits for charging H02J7/00
• CPC Class Codes: H01M 10/48 Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte constructional details of current conducting connections for detecting conditions inside cells or batteries, e.g. details of voltage sensing terminals, H01M50/569
• CPC Class Codes: H01M 10/488 Cells or batteries combined with indicating means for external visualization of the condition, e.g. by change of colour or of light density
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

A rechargeable electric tool includes a warning device which monitors a voltage of a power source battery and indicates a warning by means of an LED or a buzzer when the power source voltage is reduced to be equal to or lower than a reference voltage. The tool is configured such that, even when the warning is indicated, a control to interrupt a power supply to a motor is not performed, thereby enabling a usual operation in response to an activating operation on a trigger switch.

Claims

1. A rechargeable electric tool comprising:

a power source which is a secondary battery;

a power source switch that is electrically coupled to the power source and adapted to complete an initializing operation in the rechargeable electric tool and place the rechargeable electric tool in a standby state when the power source is electrically coupled to the rechargeable electric tool;

a trigger lever that is electrically coupled to the power source switch and adapted to complete one cycle of operation of the rechargeable electric tool when the trigger lever is pulled;

a voltage comparing device which compares a voltage of the power source with a reference voltage when the trigger lever is pulled; and

a warning device which indicates a warning in accordance with a result of the comparison of the voltage comparing device,

wherein when the voltage of the power source is reduced to be equal to or lower than the reference voltage, the warning device indicates the warning, and the trigger lever is unaffected such that the rechargeable electric tool is still operable from after the warning until the electric tool stops in response to the battery being fully discharged.

2. The rechargeable electric tool according to claim 1, wherein the reference voltage is higher than a threshold voltage at which the rechargeable electric tool is operable.

3. The rechargeable electric tool according to claim 1, wherein the trigger lever comprises a trigger switch, wherein, after the warning, the rechargeable electric tool is operable in response to an operation on the trigger switch.

4. The rechargeable electric tool according to claim 1, wherein the warning device includes a buzzer.

5. The rechargeable electric tool according to claim 1, wherein the warning device includes an LED.

6. The rechargeable electric tool according to claim 1, wherein the warning device includes a display device.