Winding – tensioning – or guiding – Reeling device – With spring motor
Utility Patent
1998-08-27
2001-01-02
Jillions, John M. (Department: 3653)
Winding, tensioning, or guiding
Reeling device
With spring motor
C242S381100, C242S381500, C033S756000, C033S762000
Utility Patent
active
06168107
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to the field of transducers. More particularly, the present invention relates to the field of restraining means for linear transducers which are cable extension transducers.
2. Description of the Prior Art
Specifically, prior art linear transducers which are cable extension transducers known as CETs are measuring devices which utilize a flexible high strength cable wound around a precision diameter cylindrical spool that turns as the cable reels and unreels from the spool. The spool is coupled to a shaft of a rotational sensor, such as an encoder or potentiometer. As the transducer's cable extends along with a movable object, it causes the spool and sensor shafts to rotate. The rotating shaft creates an electrical signal proportional to the cable's linear extension or velocity. The signal is in pules per inch of cable displacement for an encoder and volts per inch of cable displacement for a potentiometer.
To maintain cable tension, a flat wound torsion spring is coupled to the rotating shaft. Tension on the cable is maintained to insure accuracy of measurement. In addition, control of the extended cable by the torsion spring provides a reasonably constant torque to the spool as it is rotated when the cable is extended and when the cable is retracted. Since the torsion spring applies a torque to the spool during its rotation, when the cable is in its extended condition and is suddenly released (accidentally or by failure due to damage), the spool will accelerate its rotation due to the constant torque being applied, and the cable will return to the unit housing at a very high speed, resulting in self-destruction and/or damage to critical and expensive parts used in the linear transducer.
It is desirable to provide a linear transducer with the capability of restraining the returned cable at a high speed to the spool if it is suddenly released and allowed to freely return on the rotating spool, and thereby prevents self-destruction and/or damage to critical and expensive parts used in the linear transducer by the returning cable due to the constant torque being applied by the torsion spring.
SUMMARY OF THE INVENTION
The present invention is a novel and unique restraining means for use in conjunction with a linear transducer such as a cable extension transducer known as a CET. More particularly, the present invention restraining means comprises a plurality of spaced apart magnets positioned on the periphery of a stationary mounting frame, where the magnets provide a reverse torque and restrict excessive rotational speed of a spool when a copper disc or equivalent magnetic flux medium is rotated at a close proximity to the face of the magnets.
It has been discovered, according to the present invention, that by utilizing a restraining means with a linear transducer, and when a cable is suddenly released and allowed to freely return on a rotating spool, the restraining means restrains the high rotational speed at which the cable can accelerate when returning or retracting to the spool, such that the restraining means prevents the cable from self-destruction and/or damage to the linear transducer.
It is an object of the present invention to provide a linear transducer with a restraining means for restraining the high speed at which the cable can accelerate in returning or retracting to the self-contained housing of the linear transducer, so that the restraining means prevents the self-destruction and/or damage to the linear transducer.
In the preferred embodiment of the present invention, the restraining means is an eddy current brake that is sensitive to rotation and generates a reverse torque as the rotation of the spool is increased. The restraining means comprises a plurality of spaced apart circular magnets which attach to the interior periphery of a stationary mounting frame. A copper disc or equivalent magnetic flux means is attached to the rotating spool and rotates with the spool at a close proximity to the face of the magnets and provides the breaking of the magnetic field to apply a reverse torque that is proportional to the speed of the spool's rotation.
In an alternative arrangement of the preferred embodiment of the present invention restraining means, the plurality of spaced apart circular magnets are attached to the periphery of the rotating spool while the copper disc or equivalent magnet flux means is attached to the stationary mounting frame. The stationary copper disc controls the magnetic flux generated by the magnets to reduce the acceleration speed of the spool's rotation.
In another alternative arrangement of the preferred embodiment of the present invention restraining means, a donut-shaped magnet is affixed to a stationary mounting frame while a copper disc or equivalent magnet flux means is attached to a rotating spool. The rotating copper disc provides the breaking of the magnetic field to apply a reverse torque that is proportional to the speed of the spool's rotation, and thereby reduces the accelerating speed of the spool's rotation.
In a still another alternative arrangement of the preferred embodiment of the present invention restraining means, a donut-shaped magnet is attached to a rotating spool while a copper disc or equivalent magnet flux means is fixed to a stationary mounting frame.
In an alternative embodiment of the present invention, the present invention restraining means is a frictional centrifugal clutch. It comprises an outer stationary housing, an inner rotating plate, rotating brake shoes, and compression springs that are speed sensitive and expand the shoes against the spring force until they rub against the surface of the stationary housing to provide friction and slow down the rotation of the spool. The inner plate is coupled to the rotating shaft of a linear transducer which provides a frictional torque proportional to the speed at which the rotating inner plate throws the rotating brake shoes against the stationary housing, generating a reverse torque as the rotation is increased. This torque will be proportional to the speed of rotation, and slows down the increasing speed of the spool until it has reached a controllable rate that will be maintained by the retracting cable and spool rpm.
Further novel features and other objects of the present invention will become apparent from the following detailed description, discussion and the appended claims, taken in conjunction with the drawings.
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Bishop James A.
Ennis Glen M.
Malek Jack H.
Celesco Transducer Products, Inc.
Chen Tony D.
Fong Jerry
Jillions John M.
Rozsa Thomas I.
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