1. Field of the Invention
This invention relates to a wrench that utilizes a flywheel to create a high inertia torque system for removing fastening devices and a method for using the wrench.
2. Background of Related Art
A wrench that transfers energy stored in a flywheel to a bolt or nut which is to be loosened is conventionally known in the automobile lugnut removal field. U.S. Pat. No. 5,158,354 to Simonin discloses a conventional wrench with a drive motor and flywheel that are rigidly connected in a housing to drive an output ferrule when a spring clutch is engaged. In operation, a user provides power to the drive motor which causes a flywheel to rotate. Once the flywheel achieves a predetermined speed, the user presses the output ferrule onto a lugnut which causes a single tooth clutch plate connected to the ferrule to collide with a mating single tooth clutch plate connected to the flywheel. The rotational energy from the flywheel is then transferred to the output ferrule to provide a removal force to a lugnut engaged by the ferrule. The conventionally known wrench is designed for the specific purpose of quickly removing a flat tire. Accordingly, the conventional wrench is designed to be economically made with little concern for accuracy or endurance.
Because the motor of the conventionally known flywheel wrench is rigidly connected to the housing, a torque reaction will be transmitted directly to the user of the device. Torque reaction is a detrimental reverse torque which results from the elastic collision of the clutch mechanism when the rotational energy transmitted from the flywheel to the output ferrule is converted to a torque for removing a fastener. Transmission of torque reaction to an operator can lead to many undesirable health problems including nerve damage, muscle strain and bruising. Torque reaction is especially large when the rotational energy stored in the flywheel is not sufficient to remove the fastener to which the output ferrule is connected. Torque reaction is also compounded when any of the mechanisms that are rotated are not concentric. The nature and object of conventionally known flywheel wrenches has never demanded a strict limit to the amount of torque reaction that is acceptable because conventionally known flywheel wrenches are generally used in lightweight limited use applications, such as removing a lugnut from an automobile wheel. Accordingly, the detrimental effects of torque reaction being transmitted to an operator are negligible in conventionally known flywheel wrenches and do not outweigh the benefits of making the device economical and compact.
In heavier, industrial applications, it is conventionally known to use an impact wrench to remove fasteners. The impact wrench also suffers from the problem of transmission of torque reaction to the operator. In addition, the user of an impact wrench has little control over the amount of torque that is output by the tool. Torque output from air operated power equipment, such as an impact wrench, varies greatly depending on the air pressure, amount of moisture in the air and the condition of the motor itself. Furthermore, impact wrenches require a relatively large amount of input power to achieve a given output torque.