Measuring and testing – Dynamometers – Responsive to torque
Reexamination Certificate
1999-02-19
2001-03-06
McCall, Eric S. (Department: 2855)
Measuring and testing
Dynamometers
Responsive to torque
C073S862230, C073S761000, C173S176000
Reexamination Certificate
active
06196071
ABSTRACT:
FIELD OF THE INVENTION
The subject invention relates to a system by which the torque applied to a fastener such as a bolt or nut may be measured simply and accurately. More particularly, the invention relates to apparatus and methods by which the torque applied to a fastener by a socket wrench can be measured accurately and displayed quickly so that the placement of possibly damaging excessive amounts of pressure on the fastener can be avoided.
BACKGROUND OF THE INVENTION
Standard torque wrenches are essentially cantilever beams having a socket attached at one end and a grip handle at a generally opposing end. That possibly damaging excessive amounts of pressure may be applied to the bolt or nut fastener—that is, “overtorquing” the fastener—is always a danger when using such tools.
Certain socket wrenches include a mechanical dial indicator that identifies the degree to which the beam is being bent when force is exerted on the handle in order to tighten the nut or bolt fastener. Other conventional torque wrench systems do not use an indicator but instead provide an audible signal when a certain level of force has been applied to the fastener. To prevent “overtorquing”, an additional conventional torque wrench system includes a ratchet system in the handle that releases when a certain level of force has been applied to the fastener.
A number of disadvantages are associated with the conventional socket wrenches that include torque indicators. Typically, the beam of the conventional wrench system must be perfectly perpendicular to the long axis of the fastener in order that the torque applied to the fastener through the wrench can be measured accurately. Such a perpendicular alignment is difficult to attain quickly when working with most fasteners. Also, such a perpendicular alignment cannot be obtained when the wrench includes a “universal joint” type. of socket extension. Additionally, the conventional torque socket with indicator are cumbersome and difficult to place properly in tight places.
A demand therefore exists for a simplified system by which the torque placed on a fastener can be measured quickly and accurately. The present invention satisfies the demand.
The system of the present invention utilizes magneto—elastic technology to detect changes in an external magnetic field created by a circumferentially magnetized element attached to or integrated with a shaft and proportional to the torque applied to the shaft. The system includes an extension element and a converter/display unit that is in communication with the extension element such as through a signal cable.
More specifically, the extension element includes a base, a magnetized ring, a sensor, and a cover that not only extends over the surface of the magnetized ring but also by which the sensor is positioned adjacent to the ring. The base is sized and shaped and constructed such that the pressure applied to the socket wrench can be transferred to a standard socket and thereby the fastener. A circumferentially magnetized, magnetorestrictive ring is rigidly attached to an outer surface of and around a center portion of the base. A sensor that can measure the Hall effect or similar magnetic field intensity is positioned adjacent to but spaced from the magnetized ring by a cover that can surround the ring. The converter/display unit of the system can receive—such as through a cable—the information from the sensor regarding the torque that is being placed on the extension element and thereby the socket to which it is attached and convert and display the information in a readily usable form such as torque units.
One advantage of the present invention is that the system provides accurate measurements of the torque that is being placed on a fastener quickly and without excessive preparations in positioning the system relative to the fastener.
Another advantage of the present invention is that the system can accept and use standard sockets and socket wrenches thereby avoiding the need for replacement of all of the components of a conventional wrench system.
An additional advantage of the present invention is that the system is of a simplified construction that increases the reliability of the system while decreasing the cost of manufacturing the system.
It is, accordingly, a general object of the present invention to provide a system by which the torque placed on a socket through the use of a socket wrench can be measured quickly and without excessive adjustment and preparation of the system relative to the fastener.
Another object of the present invention is to provide a system that can utilize standard sockets and socket wrenches thereby providing a universal system for measuring torque.
An added object of the present invention is to provide a system that allows socket wrenches to be used such that pressure need not be placed uniformly on the wrench beam and/or the socket in order to obtain an accurate torque reading.
An additional object of the present invention is to provide a system that is of a simplified and thereby reliable construction that can be produced at a low cost.
These and other objects, features, and advantages of this invention will be. clearly understood and explained with reference to the accompanying drawings and through a consideration of the following detailed description of the preferred embodiments.
REFERENCES:
patent: 4091664 (1978-05-01), Zerver
patent: 4218828 (1980-08-01), Hoting et al.
patent: 4226127 (1980-10-01), Hardiman
patent: 4244434 (1981-01-01), Wilson
patent: 4257263 (1981-03-01), Herrgen
patent: 4265109 (1981-05-01), Hallbauer et al.
patent: 4283830 (1981-08-01), Gallizio et al.
patent: 5236053 (1993-08-01), Butsch
McCall Eric S.
Valauskas Charles C.
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