Supports – Pipe or cable – Brackets
Reexamination Certificate
1999-06-10
2001-08-14
King, Anita M. (Department: 3632)
Supports
Pipe or cable
Brackets
C248S074100
Reexamination Certificate
active
06273373
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to clamping devices, and, more particularly to a clamping device that clamps a transducer to a pipe using a modified turnbuckle assembly that assures self alignment of the transducer.
2. Discussion of Related Art
The measurement of flow rate within a pipe is important for purposes of maintenance and management of pipeline systems. It is known that an ultrasonic signal can be diagonally passed through the fluid in the pipe to measure fluid flow without intrusion into the pipe. The ultrasonic signal is transmitted from a first transducer and received by a second transducer. In operation, an ultrasonic signal is transmitted from an upstream (with regard to the direction of fluid flow within the pipe) transducer to a downstream transducer and from the downstream transducer to the upstream transducer. In each case, the time between transmission and reception of the ultrasonic signal is measured. The velocity of the fluid flow V
F
through the pipe can be determined by the equation:
V
F
=
Kc
Δ
t
TL
(
1
)
wherein Kc is a dimensioned constant(vol/time) related to the pipe, (&Dgr;t) is the difference between the downstream and the upstream transit times, and TL is the average transit time through the fluid.
However, the effect of the fluid flow on the transit times of the downstream and upstream signal is small, so it is essential that an accurate measurement of transit times is made. To determine the transit time of the signal, a phase difference between a reference signal and the received signal may be utilized. Yet, to measure phase difference, the same cycle of the reference and received signals (e.g., a first reference cycle and a first received cycle) should be compared. A comparison between different cycles of the reference and received signals results in misregistration between the reference and the received signal. Misregistration results in a large measurement error in the transit time because the transmitted ultrasonic signal has a relative low time resolution when compared to the upstream/downstream transit times. The ultrasonic signal typically has a period of from hundreds to thousands of nanoseconds while the upstream/downstream transit times are typically from picoseconds to a few nanoseconds. Accordingly, misregistration (e.g., of either the upstream or downstream signal) results in an error in the measurement of the transit time for the misregistered signal (e.g., either downstream or upstream signals) that is much larger than the transit time itself.
In practice, the setup conditions of the transducers including the pipe material, wall thickness, fluid flow rate, etc., affect the received ultrasonic signal. In addition, the beginning of the received signal does not arrive with a sharp leading edge, but rather there is a gradual buildup of the received signal. This is due to a high “Q” (resonance) of the ultrasonic transducer (transmitter) and due to sonic resonance of the pipe wall or other structure through which the ultrasonic signal passes to enter and leave(on the receiving transducer side) the fluid flow.
Clamping such transducers to a respective pipe typically requires a tedious and time consuming procedure. For example, 5 brackets are commonly used to assure that each transducer is properly aligned with the pipe. However, to assure proper alignment, the clamping procedure using brackets takes several minutes or more. In addition, different sized brackets are required depending on the circumference of the pipe.
It is therefore an object of the present invention to overcome the deficiencies of the prior art. Therefore, a need exists for a clamping device for aligning and clamping a transducer to a pipe. A further need exists for a clamping device which is capable of attaching a transducer to a pipe of any size. A still further need exists for a clamping device which is capable of being used for quick, easy and accurate installation on a pipe.
SUMMARY OF THE INVENTION
An inventive turnbuckle assembly is disclosed that quickly clamps a transducer to a pipe of any size. The assembly includes a threaded rod, a threaded knob, a washer, a rotatable spindle and a collar having an opened hook. In addition, assembly includes a fixed end nut having a closed hook for securing a link of a ladder chain that is placed around the pipe. When the knob is rotated clockwise, force is applied on the rotatable spindle.
The position of the chain on the open hook is substantially on the same plane as the center axis of rotatable spindle, so that the alignment of the transducer on the pipe is ensured. Further, the rotation of the spindle will assure that the chain's angle to the pipe is substantially equal on both sides of the pipe.
In accordance with the present invention, an apparatus for clamping and aligning an object to a cylinder includes a retainer for attaching to the object. The retainer includes an attachment device for detachably receiving a flexible retaining member, and a collar disposed on an opposite side of the retainer. A threaded rod includes a first end portion. The first end portion is adapted to receive a first end of the flexible retaining member. The threaded rod is attached to and is transversely disposed to a spindle such that the first end portion extends beyond the spindle. The spindle is received in the collar to provide a hinged connection between the retainer and the threaded rod. A knob is included for threadedly engaging a second end portion of the threaded rod. A washer is disposed between the knob and the collar such that when the knob is adjusted the flexible member is tightened around the cylinder to self align the object, and the threaded rod is pivoted about the collar to form substantially equal angles between the flexible member and the cylinder on opposite sides of the object.
Another apparatus for clamping and aligning a transducer to a pipe includes a retainer having attachment means for attaching the retainer of the transducer. The retainer includes a hook for detachably receiving a chain, and the retainer further includes a collar disposed on an opposite side of the retainer relative to the hook. A threaded rod has a first end portion, and the first end portion is adapted to receive a first end of the chain. The threaded rod is attached to and transversely disposed relative to a spindle such that the first end portion extends beyond the spindle and receives a nut for rotatably securing the threaded rod to the collar. The spindle is received in the collar to provide a hinged connection between the retainer and the threaded rod. A knob for threadedly engaging a second end portion of the threaded rod is provided. A washer is disposed between the knob and the collar such that when the knob is adjusted the chain is tightened around the pipe to self align the transducer, and the threaded rod is pivoted about the collar for rotating in accordance with tension in the chain such that substantially equal angles are formed between the chain and the pipe on opposite sides of the transducer.
In alternate embodiments, the object may be a transducer. The cylinder may include a pipe, and the flexible retaining member may include a chain. The flexible retaining member is preferably a ladder chain. The attachment member may include a hook for passing through and retaining a link of the chain. The retainer may be secured to a top surface of the object. The threaded rod may be disposed substantially perpendicular to the spindle.
The object contacts the cylinder at a contact point, and the contact point forms a tangential plane relative to the cylinder. The attachment member preferably includes a point of attachment for the flexible member at a location which is substantially coplanar with an axis of rotation provided by the spindle, and the axis of rotation of the spindle and the point of attachment for the flexible member preferably form a second plane substantially parallel to the tangential plane.
A method for clamping and aligning an obj
Bitetto James J.
F. Chau & Associates LLP
King Anita M.
Sy Holly N.
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