BACKGROUND
In the field of utility cable installation (e.g., optical fiber cable installation), there are existing techniques for using the viscous flow of a fluid, such as air, through ducts to install utility cables within the ducts. Such cable “blowing” techniques have been applied to the installation of utility cables in building risers, over relatively short distances along the ground, or in suspended cables. Existing cable blowing techniques, however, are difficult to apply over distances spanning more than a few kilometers. The flow of a fluid through an extremely long and narrow duct becomes greatly impeded due primarily to viscous flow characteristics, resulting in a high back-pressure experienced at the originating end of the duct. This problem can limit the distances over which existing cable blowing techniques are applied, and can impose constraints on the types of ducts that can be used, as well as the types of cables that may be deployed within a given duct. Additionally, existing cable blowing techniques require that relatively high pressures be applied to the end of a duct through which a cable is being fed. These high pressures can result in duct “blow-outs,” where the high pressure causes ruptures in the walls of the duct, or sealing/clamping failures, where the seal between the duct and the unit applying pressurized fluid to the duct ruptures or fails.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1A, 1B, and 1C are diagrams that depict an impulse driving fluid jetting device according to exemplary embodiments;
FIGS. 2-4 are diagrams that depict the operation of the impulse driving fluid jetting device of FIGS. 1A and 1B when generating fluid impulses;
FIGS. 5 and 6 are diagrams that depict the operation of the impulse driving fluid jetting device of FIGS. 1A and 1B, as controlled by a control device, in moving a cable within a duct;
FIG. 7 is a diagram that depicts exemplary components of control device 500 of impulse driving fluid jetting device 100; and
FIG. 8 is a flow diagram that illustrates an exemplary process for achieving resonance to cause cable movement within a duct by adjusting the magnitude, duration, and frequency of the fluid impulses jetted from the nozzle of device 100.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The following detailed description refers to the accompanying drawings. The same reference numbers in different drawings may identify the same or similar elements. The following detailed description does not limit the invention.
Exemplary embodiments described herein relate to a fluid jetting device that generates dynamically adjustable impulse fluid impulses for use in expelling, or inserting, cables from or into ducts. The magnitude, duration and frequency of fluid impulses jetted from a nozzle of the device may be adjusted to achieve a vibratory resonance condition within the duct that facilitates the movement of the cable into, or out of, the duct.
FIGS. 1A and 1B depict an impulse driving fluid jetting device 100 according to an exemplary embodiment. FIG. 1A depicts a cut-away cross-sectional view of device 100, and FIG. 1B depicts an external side view of device 100. As can be seen in FIGS. 1A and 1B, impulse driving fluid jetting device 100 includes a hollow cylinder 105, a piston 110 inside cylinder 105, a rotatable disk valve 115 partially inside cylinder 105, and a hollow fluid jetting tube 120 into which a portion of disk valve 115 protrudes. The portion of disk valve 115 protruding from cylinder 105 into jetting tube 120 does not segregate fluid in the left hand portion of jetting tube 120 from fluid in the right hand portion of jetting tube 120, those fluid portions thus being continuous. Device 100 may additionally include a control device (not shown) that is further described below with respect to FIGS. 5-7. Cylinder 105, in one implementation, may include a cylindrical structure with a round inner diameter and with a disk-like piston 110, having a circular outer diameter, that has a leak-tight fit with the round inner diameter of cylinder 105. In an alternative implementation, cylinder 105 may not include a cylindrical structure at all, but may include, for example, a structure having a rectangular cross-section and with a piston 110 having a rectangular perimeter that has a leak-tight fit with the rectangular inner surface of cylinder 105. Cylinder 105 may include a port 125 to receive a fluid supply line 130, and a pressure sensor 135. Piston 110 may include a piston rod 140. Disk valve 115 may include a rotatable disk valve shaft 145 and a disk valve channel 150. Fluid jetting tube 120 may include a disk valve slot 155, a jetting tube nozzle 160, and an impulse sensor 165. Disk valve 115 may have a cylindrical, disk-like shape, and disk valve slot 155 may be shaped to accommodate a leak-tight fit between the portion of disk valve 115 protruding into tube 120, and the disk valve slot 155 through which it protrudes. Fluid supply line 130 may include a one-way fluid valve 170.
As depicted in the embodiment of FIGS. 1A and 1B, cylinder 105 may include a cylindrical housing in which piston 110 moves inside cylinder 105 in an up and down direction in accordance with force applied to piston rod 140. Fluid supply line 130 may connect to cylinder 105 via port 125 to supply fluid into cylinder 105. The internal volume within cylinder 105 may be decreased by moving piston rod 140 in the down direction thereby decreasing an internal volume of that portion of cylinder 105 bounded by piston 110 and which contains fluid supplied by supply line 130. Pressure sensor 135 may sense the pressure in cylinder 105. Disk valve 115 may rotate (shown clockwise, but could alternatively be counter-clockwise) around disk valve shaft 145, at a rate controlled by a motor or other mechanical actuator (not shown), within disk valve slot 155 of fluid jetting tube 120. Disk valve slot 155 may include an opening in tube 120 that includes the aforementioned leak-tight fit to a lower surface of disk valve 115 when disk valve 115 is mounted to cylinder 105 via disk valve shaft 145.
Various mechanisms may be used for mounting disk valve 115 within cylinder 105 to permit rotation of disk valve 115 around a fixed axis of rotation. In the implementation depicted in FIGS. 1A and 1B, a hole through disk valve 115, into which disk valve shaft 145 is inserted, may be used for mounting disk valve 115 within cylinder 105. In another implementation (not shown), spindle arms may extend from a body of disk valve 115 into notches in the inner wall of cylinder 105. In this implementation disk valve 115, and the spindle arms, may spin about an axis of rotation within the notches in the inner wall of cylinder 105. In yet another implementation (not shown), two spindle arms may extend from the inner wall of cylinder 105 on opposite sides of the inner wall of cylinder 105. Disk valve 115 may include notches in a center of each of its flat sides. Disk valve 115 may be mounted within cylinder 105 such that a first spindle arm on a first side of the inner wall of cylinder 105 extends into a first notch in the center of one flat side of disk valve 115 and a second spindle arm on a second side of the inner wall of cylinder 105 extends into a second notch in the center of the other flat side of disk valve 115. In this latter implementation, disk valve 115 spins about an axis of rotation definied by the spindle arms on each side of disk valve 115.
In an embodiment, disk valve 115 may be formed as a single disk, with disk valve channel 150 including a straight cylindrical hole (or other cross-sectional shape) that extends internally through disk valve 115 such that each end of channel 150 opens upon the perimeter of disk valve 115. As disk valve 115 rotates about shaft 145, disk valve channel 150, at intervals determined by the rotation speed of disk valve 115, may connect the internal volume of cylinder 105 with the interior cavity of fluid jetting tube 120 such that fluid in cylinder 105 may flow into fluid jetting tube 120 to be expelled out jetting tube nozzle 160 of fluid jetting tube 120 as a sequence of impulses 175 of fluid 170. The magnitude of the peaks of the impulses 175 of the fluid jetted out of tube 120 is proportional to the magnitude of the pressure in cylinder 105. The duration of the impulses of the jetted fluid corresponds to the duration of the interconnection of internal volume of cylinder 105 to the interior of jetting tube 120 as disk valve 115 rotates around disk shaft 145. The repetition rate of the peaks of the impulses 175 of the fluid jetted out of tube 120 is proportional to the rotation rate of disk valve 115 about disk valve shaft 145. The magnitude of the pressure in cylinder 105 is dependent upon the pressure of the fluid supplied from a fluid source (not shown) via fluid supply line 130. In an embodiment in which the fluid is compressible (e.g., air), then the pressure in cylinder 105 may be dependent upon a position of piston 110, the force applied to piston 110 via piston rod 140, and the extent to which piston 110 has compressed the fluid within the interior of cylinder 105. Impulse sensor 165 may sense the magnitude and frequency of the fluid impulses 175.
As depicted in the alternative embodiment of the cut-away side view of FIG. 1C, disk valve 115 may alternatively be formed as two disks that rotate about disk valve shaft 145. As further shown in the top view box in the bottom right corner of FIG. 1C, disk valve 115 may include a first disk 185 and a second disk 190 sandwiched together, and connected to one another, such that they both simultaneously rotate about disk valve shaft 145. In this implementation, one of the two disks (e.g., disk 190) may have, instead of disk valve channel 150 extending through the disk (as shown in FIGS. 1A and 1B), a groove or notch 180 cut into a limited portion of an outer perimeter of the disk. The groove or notch 180 is cut such that in the rotational position of disk valve 115 shown in FIG. 1C, the groove or notch 180 would extend from the internal volume of cylinder 105 into the internal cavity of fluid jetting tube 120. Disk valve notch 180 may include any type of shape cut into the outer perimeter of disk 190 of disk valve 115 that permits fluid to flow through disk valve 115 from the internal volume of cylinder 105 to the internal cavity of fluid jetting tube 120, such as, for example, a V-shaped groove, a rectangular groove, etc.
A size of the internal volume of cylinder 105, a size of piston 110, a size of channel 150 or notch 180 of disk valve 115, and a size of fluid jetting tube 120 and jetting tube nozzle 160 may be form-factor matched to ensure appropriate fluid pressures and fluid volumes within cylinder 105 and jetting tube 120 during operation of device 100, and appropriate outlet fluid pressure and outlet fluid velocity at jetting tube nozzle 160 of device 100. Therefore, the relative diameter of jetting tube 120, the inner diameter of jetting tube nozzle 160, and/or the inner diameter or rectangular cross-section of cylinder 105 may be smaller or larger than shown in FIGS. 1A, 1B and 1C. For example, the inner diameter (i.e., of the nozzle outlet) of jetting tube nozzle 160 may be smaller than the inner diameter of the outlet end of fluid jetting tube 120.
FIGS. 2-4 depict the operation of device 100 when generating fluid impulses 175 from fluid jetting tube 120. As can be seen in FIG. 2, fluid is supplied (identified by a “1”) via fluid supply line 130 to the internal volume of cylinder 105. Fluid valve 170 may open to enable the supply of the fluid into cylinder 105. The fluid may include, for example a gas (e.g, air) or a liquid (e.g., water). In the rotational position of disk valve 115 shown in FIG. 2 (identified by a “2”), disk valve channel 150 is not open to the internal volume of cylinder 105. Therefore, no fluid flows from cylinder 105 to jetting tube 120.
As further shown in FIG. 3, as disk valve 115 continues to rotate to a rotational position (identified by a “3”) in which disk valve channel 150 continues to not be open to the internal volume of cylinder 105, force is applied to piston 110 via piston rod 140 to move piston 110 (identified by a “4”) in a downward direction to decrease the internal volume of cylinder 105. In an embodiment in which the fluid supplied by supply line 130 is compressible (e.g, air), force may be applied to piston 110 via piston rod 140 to compress the fluid within cylinder 105, thereby increasing the internal pressure within cylinder 105 above the pressure of the fluid as supplied by supply line 130.
FIG. 4 depicts disk valve 115 continuing to rotate to a rotational position (identified by a “5”) in which disk valve channel 150 is open to the internal volume of cylinder 105 and to the interior of jetting tube 120. As disk valve 115 rotates such that disk valve channel 150 connects the internal volume of cylinder 105 to the interior of jetting tube 120, the fluid within cylinder 105, under pressure and including a total volume that corresponds to a position of piston 110, moves from the internal volume of cylinder 105 through channel 150 into the interior of jetting tube 120 to be expelled (identified by a “6”) from nozzle 160 of jetting tube 120. The pressure inside cylinder 105 then decreases, and fluid may be added via supply line 130.
The sequence depicted in FIGS. 2-4 may be repeated, with a control device (not shown, but described below with respect to FIGS. 5-8) controlling the rotation rate of disk valve 115, and controlling the movement and position of piston 110.
FIGS. 5 and 6 depict the operation of impulse driving fluid jetting device 100, as controlled by a control device 500, in moving a cable 510 within a duct 520. Cable 510 may include one or more optical fibers. In one implementation, duct 520 may include a microduct. FIG. 5 depicts the output jetting nozzle of impulse driving fluid jetting device 100 being applied to an inlet of duct 520. Control device 500 controls the jetting of fluid impulses 175 into the inlet of duct 520 in order to cause cable 510 to move within duct 520. The fluid impulses 175 cause vibration of cable 510 within duct 520 that dislodges cable 510 from frictional contact with the interior walls of duct 520. Control device 500, using a cable position or cable movement sensor (not shown), monitors the movement 530 of cable 510 within duct 520.
As further shown in FIG. 6, control device 500 may control the operation of device 100 such that the jetting of fluid impulses 175 from device 100 achieves a resonance condition 600 within duct 520. To achieve resonance condition 600, control device 500 controls the rotation rate of the disk valve of device 100, the pressure of fluid supplied to cylinder 105, and the position of the piston within cylinder 105, based on the monitored cable movement 530, to adjust the magnitude, duration, and frequency of the fluid impulses jetted from the nozzle of device 100. Upon achieving resonance condition 600 within duct 520, movement 610 of cable 510, in a direction coinciding with the direction of the jetting fluid from device 100, will begin such that cable 510 moves through and into or out of duct 520. In circumstances where cable 510 is being fed into duct 520, achieving resonance condition 600 within duct 520 and the resulting cable movement 610 may feed cable 510 into duct 520 in a direction coinciding with the direction of the jetting fluid impulses from device 100.
FIG. 7 is a diagram that depicts exemplary components of control device 500 of impulse driving fluid jetting device 100. Device 100 may include a sensor interface(s) 700, a piston control unit 710, a fluid valve/fluid source control unit 720, a disk valve control unit 730, a communication interface(s) 740, a processing unit 750, an input device(s) 760, a memory 770, an output device(s) 780, a storage device 785, and a bus 790.
Sensor interface(s) 700 may include one or more interfaces for communicating with sensors of device 100. For example, sensor interface(s) 700 may communicate with pressure sensor 135 and impulse sensor 165. As another example, sensor interface(s) 700 may communicate with a cable position sensor that senses the position and/or movement of a cable within a duct. Piston control unit 710 may include a motor, or other mechanical actuator, that applies force to piston rod 140 to move piston 110 within cylinder 105 based on instructions from processing unit 750. Fluid valve/fluid source control unit 720 may include a mechanical actuator for opening or closing fluid valve 170 based on instructions from processing unit 750. Fluid valve/fluid source control unit 720 may further include a mechanism for controlling the supply rate and pressure of fluid supplied by the fluid source via fluid supply line 130 to cylinder 105 of device 100.
Disk valve control unit 730 may include a motor, or other mechanical actuator, that controls the rotation rate of disk valve 115 about disk valve shaft 145 based on instructions from processing unit 750. Disk valve control unit 730 may start, stop, increase, decrease, or maintain steady, a rotation rate of disk valve 115. If the motor is a continuous rotational motor, the duration and frequency (repetition rate) of the impulses are necessary negatively-correlated, i.e., the higher the rotational speed of disk valve 115, the higher the repetition rate of the impulses and the smaller the duration of each impulse. In an alternative implementation in which the motor includes a stepper motor, the motor can provide impulse durations which are not correlated to the rotational speed of disk valve 115. In step motor mode, a first impulse of disk valve 115 can be controlled to be of a different duration than a subsequent, second impulse.
Communication interface(s) 740 may include one or more transceivers that enable control device 500 to communicate with other devices and/or systems. For example, communication interface(s) 740 may include a wireless transceiver for wirelessly communicating with a cellular network, with a wireless router or wireless network access point (e.g., Wi-Fi), or with other devices (e.g., via BlueTooth). As another example, communication interface(s) 740 may include a wired transceiver for communicating with other devices and systems (e.g., a wired network).
Processing unit 750 may include one or more processors or microprocessors, or processing logic, which may interpret and execute instructions to perform processes, such as that described below with respect to FIG. 8. Input device(s) 760 may include one or more mechanisms that permit a user/operator to input information to device 500, such as, for example, a keypad or a keyboard, a display with a touch sensitive panel, voice recognition and/or biometric mechanisms, etc. Memory 770 may include a random access memory (RAM) or another type of dynamic storage device that may store information and instructions for execution by processing unit 320. Memory 770 may further include a Read Only Memory (ROM) or another type of static storage device that may store static information and instructions for use by processing unit 750. Memory 770 and storage device 730 may each be referred to herein as a “tangible non-transitory computer-readable medium.”
Output device(s) 780 may include one or more mechanisms that output information to the user/operator of control device 500, including a display, a speaker, etc. Input device 760 and output device 780 may, in some implementations, be implemented as a user interface (UI) that displays UI information and which receives user/operator input via the UI. Storage device 785 may include a magnetic and/or optical recording medium. Bus 790 may include an electrical connection that permits the components of control device 500 to communicate with one another.
The configuration of components of control device 500 shown in FIG. 7 is for illustrative purposes. Other configurations may be implemented. Therefore, control device 500 may include additional, fewer, different, and/or differently arranged, components than those depicted in FIG. 7.
FIG. 8 is a flow diagram that illustrates an exemplary process for achieving resonance to cause cable movement within a duct by adjusting the magnitude, duration, and frequency of the fluid impulses jetted from the nozzle of device 100. The exemplary process of FIG. 8 may be implemented by control device 500, in conjunction with impulse driving fluid jetting device 100 depicted in FIG. 1A, 1B or 1C. Prior to initiating the exemplary process of FIG. 8, nozzle 160 of fluid jetting tube 120 of device 100 may be positioned against the mouth of a duct from which a cable is being expelled, or into which a cable is being inserted. Nozzle 160 tightly encloses the mouth of the duct or is snug-fit inserted into the mouth of the duct to ensure that the force associated with fluid impulses 175 is applied to the task of moving the cable inside the duct.
The exemplary process may include control device 500 adjusting the fluid pressure of fluid supplied to cylinder 105 via fluid supply line 130 (block 800). Control unit 720 of control device 500 may send a signal to open one-way fluid valve 170 of fluid supply line 130, and may send signals to the fluid source supplying fluid via supply line 130 to supply the fluid at a particular pressure and fluid rate.
Control device 500 may adjust the position of cylinder piston 110 to change the cylinder volume and the total volume of fluid in cylinder 105 (block 810). Piston control unit 710 of control device 500 may control the motor/mechanical actuator to apply force to piston 110 via piston rod 140 to cause piston 110 to move within cylinder 105 to produce a target internal volume and/or target internal pressure (e.g., if the fluid is compressible) of cylinder 105. The movement of piston 110 to produce the target internal volume and/or target internal pressure of cylinder 105, in turn, produces a total volume of fluid within cylinder 105 that can be expelled into fluid jetting tube 120 when via 150 of disk valve 115 spins into a position that produces an opening between the internal volume of cylinder 105 and the interior of fluid jetting tube 120.
Control device 500 may adjust the spinning rate of disk valve 115 to set the jetting impulse frequency (block 820). Disk valve control unit 730 may, based on instructions from processing unit 750, adjust the spinning rate of disk valve 115, including increasing or decreasing the rotation rate of disk valve 115. Control device 500 may monitor movement of the cable within the duct (block 830). Sensor interface(s) 700 of control device 500 may communicate with a sensor monitoring the position and/or movement of the cable within the duct to receive cable position and/or cable movement data.
Control device 500 may determine, based on the movement of the cable, whether the current fluid pressure, impulse jetting frequency, and cylinder volume achieves resonance to cause a maximum length-wise movement of the cable within the duct (block 840). A particular combination of the fluid pressure, the impulse jetting frequency, and the cylinder volume will cause a vibratory resonance condition associated with the duct within which the cable is being removed, or inserted, that causes a maximum amount of movement of the cable within the duct.
If resonance is not achieved (NO—block 850), then the exemplary process may return to block 800 with further adjustment of the fluid pressure, cylinder volume, and disk valve spinning rate. If resonance is achieved (YES—block 850), then control device 500 may maintain the current fluid pressure, cylinder volume and disk valve spinning rate of device 100 to facilitate the movement of the cable within the duct (block 860). Once resonance is achieved, the exemplary process may continuously, or periodically, re-check the resonance condition that causes maximum movement of the cable within duct (block 850). The vibratory resonance condition is not constant, but depends on a distance that the cable is extended within the duct and upon on a length of the duct. Therefore, resistance to movement of the cable increases as more of the cable is within the duct, and resistance to movement of the cable decreases as less of the cable is within the duct. As the cable moves within duct, the fluid pressure, cylinder volume and disk valve spinning rate may have to be adjusted to maintain the vibratory resonance condition and the maximum cable movement rate. The continuous, or periodic, re-checking of the resonance state is depicted in FIG. 8 as including the sequence of blocks 860, 840 and 850. Upon a determination, in block 850, that resonance no longer exists, the exemplary process may return to block 800 with a re-adjustment of the fluid pressure, the cylinder volume, and the disk valve spinning rate. The exemplary process of blocks 800-860 may continue until the cable is completely expelled from the duct in circumstances where the cable is being removed from the duct, or until the cable is completely inserted into the duct in circumstances where the cable is being installed in the duct.
The foregoing description of implementations provides illustration and description, but is not intended to be exhaustive or to limit the invention to the precise form disclosed. Modifications and variations are possible in light of the above teachings or may be acquired from practice of the invention. For example, while series of blocks have been described with respect to FIG. 8, the order of the blocks may be varied in other implementations.
Certain features described above may be implemented as “logic” or a “unit” that performs one or more functions. This logic or unit may include hardware, such as one or more processors, microprocessors, application specific integrated circuits, or field programmable gate arrays, software, or a combination of hardware and software.
No element, act, or instruction used in the description of the present application should be construed as critical or essential to the invention unless explicitly described as such. Also, as used herein, the article “a” is intended to include one or more items. Further, the phrase “based on” is intended to mean “based, at least in part, on” unless explicitly stated otherwise.
In the preceding specification, various preferred embodiments have been described with reference to the accompanying drawings. It will, however, be evident that various modifications and changes may be made thereto, and additional embodiments may be implemented, without departing from the broader scope of the invention as set forth in the claims that follow. The specification and drawings are accordingly to be regarded in an illustrative rather than restrictive sense.
Patent Application
20150316041
