Patent ID: 7263916

Claim:
An electric wrench, comprising: a main body further including an enlarged head portion, a handle and a neck portion connecting said head portion and said handle, a first side of said head portion being provided with a fixed jaw and a second side a movable jaw with a gear-teethed inner bottom thereof, a slot formed aside said fixed jaw toward said movable jaw, whereby said movable jaw can slide along said slot, said head portion being further provided with an inner receptacle connected to said slot, said handle and said neck portion being respectively provided with a first open inner space and a second open inner space; a worm gear disposed in said receptacle and engaged with said movable jaw, whereby said movable jaw can slide toward or away from said fixed jaw; a flexible member disposed between said worm gear and a major gear wheel, whereby said flexible member will be twisted, said major gear wheel and a minor gear being connected through a first transmission member; wherein the worn gear and the major gear wheel are coaxially aligned and have slots on for retaining a torsion spring therebetween; further, the major gear wheel is connected with a minor gear wheel having an outer gear wall through the transmission member with an inner gear surface whereby the major gear wheel and the minor gear wheel are moved synchronically; a motor housed in said first open space and connected to said minor gear wheel through a second transmission member, said motor being electrically connected to a battery in said second open space; a switch unit electrically connected said motor for controlling the activation of said motor; and a side cover detachable from said main body for covering said first and said second open spaces; and wherein said second transmission member is a torsion spring with two end connectors respectively coupled with said minor gear wheel and said motor; the second transmission member is a flexible part housed in the second region and the two end connectors are two T-shaped first and second connectors, being respectively coupled with a shaft of the minor gear wheel and a shaft of the motor; wherein buttons of said switch unit are lower than the main body surface around said buttons for preventing accidental touches by a holding hand; wherein said switch unit is located in said neck portion of said wrench; and wherein the switch unit is housed in the neck portion; one side of the switch unit is mounted on a retaining plate, and the opposite side thereof is supported against a hole in the main body and the through hole of the side cover, the two buttons of the switch unit move oppositely by pivoting about a fixed column going through a middle hole on the retaining plate; there are electrodes and springs between the button switch unit and the retaining plate.