Implements or apparatus for applying pushing or pulling force – Method or apparatus for placement of conductive wire – By fluid pressure differential in conduit
Reexamination Certificate
2002-07-22
2004-06-08
Wilson, Lee D. (Department: 3723)
Implements or apparatus for applying pushing or pulling force
Method or apparatus for placement of conductive wire
By fluid pressure differential in conduit
C254S13430R
Reexamination Certificate
active
06746000
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a line-inserting method, a line for inserting and an optical transmission line for inserting.
2. Description of the Related Art
U.S. Pat. No. 4,498,659, as a first prior art of the present invention, discloses the technique of connecting a flexible plastic cone member having an external diameter approximately equal to the internal diameter of the conduit to an end of a line for inserting a cable, pushing the flexible plastic cone member into the conduit from one end thereof, and blowing air into the conduit or sucking air therefrom, whereby the flexible plastic cone member is moved to the opposite end of the conduit.
U.S. Pat. No. 3,119,600, as a second prior art of the present invention, discloses the technique of pushing a soft ring member provided around a hose of a vacuum suction device into one end of the conduit.
U.S. Pat. No. 3,301,531, as a third prior art of the present invention, discloses the technique of pushing a soft ring member provided around a hose of a blower device into one end of the conduit.
In the second and third prior arts, a spherical member having an external diameter approximately equal to the internal diameter of the conduit is connected to an end of a line to be used for inserting a cable to give a thrust to the line.
These prior arts, however, intend to generate a thrust for inserting the line into the conduit, using the difference in pressure on both sides of the cone member or spherical member, each having an external diameter approximately equal to the internal diameter of the conduit, and consequently has the following problems.
In the case rust and foreign substances are attached to the inner surface of the conduit, or in the case another cable has been already inserted in the conduit, the cone member or spherical member excessively increases the friction resistance against the inner surface of the conduit or already inserted cable so that the line has not been readily inserted. In the case the conduit has right-angled corners or greatly curved portions, the line is pressed against inner surfaces of the right-angled corners or greatly curved portions to generate a great friction resistance although the line is pulled by the cone member and spherical member so that the line has not been readily inserted. For these reasons, the conventional pneumatic line-insertion system has not been widely put into practical application.
The second prior art which discloses the technique of pushing one part of the soft ring member of the hose into one end of the conduit, and sucking air from the conduit via the hose has the following problems.
First, since the soft ring member is pushed into one end of the conduit in the ring-like configuration, the cone member or spherical member which has moved within the conduit are obstructed by this soft ring member so as not to be drawn from the end of the conduit.
Next, the conduit has a specific one or small number of fixed internal diameters. So, a specific part of the conical outer surface of the soft ring member is continuously pressed on one end of the conduit, and consequently, the life of the soft ring member has become short. In the case the conduit which has been embedded in the wall is connected to a joint box, for example, the soft ring member has not been readily inserted into the joint box.
In the case another cable has been already inserted in the conduit, the end of the conduit is narrowed with both the cable and soft ring member, and cannot be sealed sufficiently. This results in the air flow in the conduit becoming worse to decrease the thrust to be applied to the line for inserting the cable into the conduit.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a new line-inserting method, a new line for inserting and a new optical transmission line for inserting, which can help line-inserting into a conduit.
The line-inserting method of the present invention makes air stream into a tubular conduit(pipe for accommodating a electric cable or a communication line) and carries the line member having a tape of which a main surface is given fluid mechanical thrust by the air stream flowing along the main surface of the tape.
Almost pulling force given to the tape in the air stream is generated by the fluid mechanical thrust and little pulling force given to tape in the air stream is generated by the friction between the main surfaces of the tape and the air stream. The fluid mechanical thrust generated on the main surfaces of the tape by the air stream is typically known as a wing theory in fluid mechanics. The tape performs like a wing of the aircraft in the air stream nevertheless the tape is very thin and very soft when it is compared to the wing. Nevertheless, the thin and soft plastic tape generates a large thrust in the air stream. For the inventor, it was the large mystery. Now, the inventor may understand the true reason about easy flight of the thin and soft plastic tape in the pipe.
The thin, soft and light plastic tape is bended easily in the air stream like wave-shape and flutters. The surface shape of the bending portions of the tape is almost same as the surface shape of the wing and bends the air stream like the wing. The wing generates the large floating force and resistive force when it is compared to a plane disposed in parallel to the air stream. The resistive force generated on the bending surface of the tape becomes the fluid mechanical thrust pulling the tape into the pipe.
The second advantage of use of the fluid mechanical interference between the main surfaces of the tape and the air stream is that the contact between the inner surface of the pipe(tubular conduit) and the tape at the sharp corner of the pipe. Its reason is that the tape is bended strongly and the large resistive force generates on the tape near the corner. Further, the air stream pushes the tape to the direction to leave from the corner. Consequently, the friction between the tape and the corner does not occur. It means the tape can fly in the pipe easily over the corner of the pipe.
The third advantage of use of the fluid mechanical interference between the main surfaces of the tape and the air stream is that the tape can fly easily into the pipe if the barrier like the cable is installed in the pipe because the thin and soft tape can easily bend along the bending air stream for avoiding the barrier. As the results, the tape can fly into the pipe having the barrier without damage when it is compared to the present stainless line for inserting cable.
The fourth advantage of use of the fluid mechanical interference between the main surfaces of the tape and the air stream is that the top portion made of the tape does not generate the large friction when it is compared to the top portion of the line with a half ball-shape disclosed by the prior patents. Such as top portion with the half ball-shape moves by the difference of the pressures. This top portion with the half ball-shape requires to decrease the air leakage into the gap between the top portion and the inner surface of the pipe. As the results, the hard top portion with the half ball-shape attaches to the inner surface of the pipe and the large friction generates. The tape-shape top portion of the present invention does not have such problem and can fly easily.
The fifth advantage of use of the fluid mechanical interference between the main surfaces of the tape and the air stream is that this fluid mechanical thrust is generated every portion of the tape. As the results, the tape does not need to have the strong anti-tension force and can have a thin thickness when it is compared the line pulled by the top portion with the half ball-shape or the cone-shape. Such line pulled the only top portion has a strong anti-tension force and become heavy and hard to move. The tape-shape top portion of the present invention does not have such problem and can fly easily.
The sixth advantage of use of the fluid mechanical interference between the main surfaces of t
Tahara Hiroshi
Watanabe Masaaki
Burns Doane Swecker & Mathis L.L.P.
Ichimatsu Denki Koji Co., Ltd.
Wilson Lee D.
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