Electric tightening device

• US 7,135,791 B2
• Filed: 11/23/2005
• Issued: 11/14/2006
• Est. Priority Date: 12/01/2004
• Status: Active Grant

• Current Assignee: Maeda Metal Industries, Ltd.
• Original Assignee: Maeda Metal Industries, Ltd.
• Inventors: Torigai, Yukio, Kushida, Toshihiko
• Primary Examiner(s): Ro, Bentsu
• Application Number:
  US11/286,759
• Publication Number:
  US 20060113934A1
• Time in Patent Office: 356 Days
• Field of Search: 388/937, 307149-150, 320/107, 320112-115, 320/127, 320/134, 320/149, 320/152
• US Class Current: 307/150
• CPC Class Codes: B25B 21/00 Portable power-driven screw or nut setting or loosening tools; details or components, e.g. casings, bodies, of portable power-driven tools not particularly related to the operation performed B25F5/00; for mounting or dismounting wheels B60B29/006; Attachments for drilling apparatus serving the same purpose machines B23P19/06
• CPC Class Codes: B25B 23/147 specially adapted for electrically operated wrenches or screwdrivers
• CPC Class Codes: G01R 19/16542 for batteries charge condition monitoring in G01R31/36
• CPC Class Codes: G01R 31/3648 comprising digital calculation means, e.g. for performing an algorithm
• CPC Class Codes: G01R 31/3828 using current integration
• CPC Class Codes: G01R 31/3842 combining voltage and current measurements
• CPC Class Codes: G01R 31/40 Testing power supplies testing photovoltaic devices H02S50/10
• CPC Class Codes: Y10S 388/937 Hand tool

Abstract

A controller compares a minimum value of power source voltage which decreases in association with starting current generated upon start of a motor with a threshold value in a storing unit. When the minimum value is less than the threshold value, the controller notifies of shortage of the power source terminal voltage, and stops the motor. The controller also compares a value obtained by integrating the power source voltage which decreases in association with starting current generated upon start of the motor for only predetermined time with the threshold value in the storing unit, when the integral value is less than the threshold value, notifies of shortage of the power source terminal voltage, and stops the motor.

Claims

1. An electric tightening device comprising:

a power source that passes current to

a motor;

a current detector that detects current flowing in the motor;

a storing unit in which a threshold value of the starting current is stored; and

a controller connected to the current detector and the storing unit,

wherein the controller detects a maximum value of the starting current generated upon start of the motor by the current detector,

compares the current maximum value with the threshold value in the storing unit and,

when the current maximum value is less than the threshold value, notifies of shortage of the power source terminal voltage.

2. An electric tightening device comprising:

a power source that passes current to

a motor;

a current detector that detects current flowing in the motor;

a storing unit in which a threshold value of a value obtained by integrating the current flowing in the motor is stored; and

a controller connected to the current detector and the storing unit,

wherein the controller integrates the starting current generated upon start of the motor for only predetermined time,

compares the integral current value with the threshold value in the storing unit and,

when the integral value is less than the threshold value, notifies of shortage of the power source terminal voltage.