Dimension sensor and method for stopping expansion of a tube

A dimension sensor is used in conjunction with a tube and includes a body member and at least one detector element. The body member has an inner surface defining an opening sized to receive the tube. The at least one detector element is connected to the body member and has a detector portion extending into the opening. When the tube is received in the opening, the detector portion is initially disposed apart from the tube. A method using the dimension sensor stops expansion of the tube expanding from a pre-expanded state to a desired expanded state. A pumping device is actuated to pressurize a fluid by an amount sufficient to cause the tube to expand from the pre-expanded state to the desired expanded state. When the tube expands to the desired expanded state, the pumping device deactivates thereby stopping expansion of the tube at the desired expanded state.

FIELD OF THE INVENTION

The present invention relates to a dimension sensor. More particularly, the present invention is directed to a dimension sensor that is used in conjunction with a tube during a tube expansion process so that, when the tube achieves a desired expanded state, the tube expansion process terminates. The present invention is also directed to a method for stopping expansion of an expanding tube when the tube achieves the desired expanded state.

BACKGROUND OF THE INVENTION

In the manufacture of a conventional heat exchanger, heat exchanger tubes are inserted through respective aligned holes in a plurality of spaced-apart plate fins. Initially, the heat exchanger tubes are rather loosely received in the holes of the plate fins. It is necessary to expand the heat exchanger tubes in the holes of the plate fins so that the heat exchanger tubes are in a close-fitting, interference contact with the plate fins.

A conventional system for constructing heat exchangers using fluidic expansion by employing a fluid expansion is disclosed in U.S. Pat. No. 5,765,284 to Ali et al. As shown inFIG. 1, a compressor2of a tube expansion system3compresses an expansion fluid, specifically, a compressible fluid, from an expansion fluid reservoir4through a high-pressure safety valve6to the heat exchanger8via pipes10aand10b. The expansion fluid under high-pressure enters a tubing circuit12of the heat exchanger8through a connector14which is sealed to an inlet of the tubing circuit12. The tubing circuit12is a serpentine structure of connected heat exchanger tubes16. The connector14is a high-pressure connector capable of remaining sealed while delivering the expansion fluid at several thousand pounds per square inch. Upon introduction of the high-pressure fluid into the tubing circuit12, the heat exchanger tubes16of the serpentine structure16expand radially outwardly to form secure contact with plate fins18and tube sheets20. A plug22seals an outlet of the tubing circuit12.

As shown inFIG. 1, controls24govern the amount of pressure the compressor2supplies to the tubing circuit12. The controls24also terminate compression of the compressor2when sufficient expansion of the heat exchanger tubes16has been achieved by shutting off a power supply26supplying power to the compressor2through the controls24. The controls24are used in conjunction with a displacement sensor28. The displacement sensor28physically measures the increase in tubing diameter of a portion of one heat exchanger tube16of the tubing circuit12. The displacement sensor28provides feedback of the expansion progress of the heat exchanger tubes16to the controls24. In this manner, the controls24are set to stop the expansion of the heat exchanger tubes16once the circuit reaches a certain diameter. Alternatively, the controls24can vary the pressure of the expansion fluid during the expansion process. The controls24are essentially a microprocessor programmed in such a manner as to perform the above-stated objectives.

Another conventional tube expansion system for constructing heat exchangers uses an incompressible fluid such as water as opposed to U.S. Pat. No. 5,765,284 that uses a compressible fluid. However, other than one system using an incompressible fluid while the other uses a compressible fluid, the conventional systems for expanding heat exchanger tubes to construct heat exchangers using a fluid are generally similar in structure and function.

OBJECTS AND SUMMARY OF THE INVENTION

It is an object of the invention to provide a dimension sensor for use in manufacturing heat exchangers that shuts off a pumping device of a tube expansion system when an outer surface of the tube expands from a pre-expanded state to a desired expanded state.

It is another object of the invention to provide a dimension sensor and a method for stopping expansion of a heat exchanger tube expanding from a pre-expanded state when the heat exchanger tube expands to the desired expanded state.

It is yet another object of the invention to provide a dimension sensor and a method for stopping expansion of a tube expanding from a pre-expanded state to a desired expanded state when the tube is being expanded from a pre-expanded state to the desired expanded state by a fluid pressurized by a pumping device.

Accordingly, a dimension sensor of the present invention and a method of the present invention for stopping expansion of a tube when the desired expanded state is achieved are hereinafter described.

One embodiment of a dimension sensor of the present invention is used in conjunction with a tube and includes a body member and at least one detector element. The body member has an outer surface and an inner surface defining an opening sized to receive the tube. The at least one detector element is connected to the body member and has a detector portion extending into the opening. When the tube is received in the opening, the detector portion is initially disposed apart from the tube.

Another embodiment of a dimension sensor of the present invention is used in conjunction with a tube fabricated from an electrically conductive material to shut off a pumping device of a tube expansion system when a tubular outer surface of the tube expands from a pre-expanded state to a desired expanded state. The dimension sensor includes a body member as mentioned above and a plurality of detector elements. Each detector element is connected to the body member and has a detector portion extending into the opening. The detector portions are disposed apart from one another at a distance representing the desired expanded state of the tubular outer surface of the tube. In an opened electrical circuit condition, the tubular outer surface of the tube fails to simultaneously contact the plurality of detector elements thereby allowing expansion of the tubular outer surface. In a closed electrical circuit condition, the tubular outer surface of the tube simultaneously contacts the plurality of detector elements thereby shutting off the pumping device and thereby terminating expansion of the tubular outer surface.

Yet another embodiment of the invention is a method for stopping expansion of a tube expanding from a pre-expanded state to a desired expanded state. The tube is expanded from a pre-expanded state to the desired expanded state by a fluid pressurized by a pumping device. The method includes the step of actuating the pumping device to pressurize the fluid by an amount sufficient to cause the tube to expand from the pre-expanded state to the desired expanded state. The method also includes the step of providing a detector element operative in conjunction with the tube in the desired expanded state such that, when the tube expands to the desired expanded state, the pumping device deactivates thereby stopping expansion of the tube at the desired expanded state.

These objects and other advantages of the present invention will be better appreciated in view of the detailed description of the exemplary embodiments of the present invention with reference to the accompanying drawings, in which:

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

Hereinafter, embodiments of the present invention will be described with reference to the attached drawings. The structural components common to those of the prior art and the structural components common to respective embodiments of the present invention will be represented by the same reference numbers and repeated description thereof will be omitted.

A first exemplary embodiment of a dimension sensor110of the present invention is hereinafter described with reference toFIGS. 2-7B. As introduced inFIG. 2, the dimension sensor110is disposed between the connector14and the tube sheet20. Although not by way of limitation, heat exchanger tube16to be expanded is actually two heat exchanger tubes16connected together at ends opposite the dimension sensor110by a tube joint112bent into a semicircle to form a loop. A skilled artisan would appreciate the heat exchanger tube16to be expanded might be a single length, two connected lengths formed into a loop as illustrated, multiple connected lengths or all of the lengths connected together. At the terminal end of the loop, i.e. below the dimension sensor110is a check valve114. It is preferred but not required that a pumping device114pumps an incompressible fluid from the fluid reservoir116such as water. The pumping device114pumps the incompressible fluid through a first pipe118a, a pressure relief valve120, a second pipe118b, the connector14and into the loop. The check valve114allows any air to bleed therethrough when the pumping device114is initially activated. Once the air is bled, the check valve114closes to allow the incompressible fluid to build up pressure at an amount sufficient to expand the loop of heat exchanger tubes16. The pressure relief valve120acts as a safety in the event of over-pressurization by the pumping device114.

The dimension sensor110is used in conjunction with the heat exchanger tube16that has a tubular outer surface16aand is fabricated from an electrically conductive material such as stainless steel. The dimension sensor110surrounds a portion of the heat exchanger tube16extending outwardly from the heat exchanger8adjacent the tube sheet20and shuts off the pumping device114of the tube expansion system111when the tubular outer surface16aof the heat exchanger tube16expands from a pre-expanded state (FIGS. 5A and 6A) to a desired expanded state (FIGS. 5B and 6B)

As best shown inFIGS. 3-5B, the dimension sensor110includes a body member122and a plurality of detector elements124. More specifically, the dimension sensor110includes a pair of detector elements124. For the first exemplary embodiment of the dimension sensor110, the body member122is fabricated from an electrically non-conductive material such as resin or plastic and the detector elements124are fabricated from an electrically conductive material such as metal. The body member122is cylindrically shaped and has a body member outer surface122aand a body member inner surface122b. The body member inner surface122bdefines an opening126in the body member122that is sized to receive the heat exchanger tube16. Each detector element124is connected to the body member122and has a detector portion124aextending into the opening126. Respective ones of the detector portions124aare disposed apart from one another and face opposite one another. More particularly, the respective ones of the detector portions124aare disposed apart from one another at a distance X as shown inFIG. 5Arepresenting the desired expanded state of the tubular outer surface16aof the heat exchanger tube16.

For the first exemplary embodiment of the dimension sensor110, each detector portion124aextends generally in a radially inwardly direction relative to the heat exchanger tube16received therein. A skilled artisan would appreciate that each detector portion124aextends generally in the radially inwardly direction relative to the heat exchanger tube16because expansion of the heat exchanger tube16from a pre-expanded state to a desired expanded state results in a change of the radius of the heat exchanger tube16.

Although not by way of limitation, the opening126is cylindrically shaped. For the first exemplary embodiment of the dimension sensor110, the opening126includes a first cylindrical opening portion126aand second cylindrical opening portion126bthat are in communication with one another as best shown inFIGS. 3 and 5A. InFIG. 5A, the first cylindrical opening portion126ahas a first diameter Da and the second cylindrical opening portion126bhas a second diameter Db that is smaller than the first diameter Da. Further, respective ones of the detector portions124aof the pair of detector elements124are disposed in the first cylindrical opening portion124a.

For the first exemplary embodiment of the dimension sensor110, the detector elements124includes a threaded screw shaft128fabricated from metal and threadably engaged with the body member122as best shown inFIGS. 5A and 5B. One of ordinary skill in the art would appreciate that the detector elements124are set screws. Each threaded screw shaft128has a slotted head128a. Each detector portion124ais operative to move towards and away from the heat exchanger tube16upon turning the threaded screw shaft128, for example, by turning the slotted head128ausing a screwdriver. Also, each detector element124includes a nut130that is threadably engaged with the threaded screw shaft128and is disposed exteriorly of the body member122. The nut130is operative to engage the body member outer surface122aand to secure the threaded screw shaft to body member122.

Additionally, a lead wire132is connected to each one the detector elements124. The lead wires132can be secured to the detector elements124by any conventional manner. By way of example only, the lead wires132are connected to the detector elements124by weldments134.

As illustrated inFIGS. 2,6A and6B, the tube expansion system111includes a controller136and the power supply26in electrical communication with the pumping device114via wires represented by dashed lines. Also, the controller136is in electrical communication with the dimension sensor110via wires represented by dashed lines. Furthermore, an electrical source138, such as a battery, is disposed in a manner to electrically connect the controller136with the dimension sensor110. The dimension sensor110is disposed around a portion the heat exchanger tube16and is positioned facially against the tube sheet20.

Since the pair of detector elements124and the heat exchanger tube16are fabricated from electrically-conductive materials, a person of ordinary skill in the art would appreciate that the pair of detector elements124and the heat exchanger tube16combine to form a first electrical circuit condition when the heat exchanger tube16is in the pre-expanded state (FIG. 6A) and form a second electrical circuit condition when the heat exchanger tube16is in the desired expanded state (FIG. 6B). Specifically, for the first exemplary embodiment of the dimension sensor110, the first electrical circuit condition (FIG. 6A) is an opened electrical circuit condition having a zero voltage potential V0and the second electrical circuit condition (FIG. 6B) is a closed electrical circuit condition generating a positive voltage potential V+. In the opened electrical circuit condition shown inFIG. 6A, the tubular outer surface16aof the heat exchanger tube16fails to simultaneously contact the pair of detector elements124, thereby allowing expansion of the tubular outer surface16awhen the pumping device114is activated to pump the fluid (illustrated as an arrow). For activating the pumping device114, the power supply26provides a voltage potential Vps+. In the closed electrical circuit condition (FIG. 6B), the tubular outer surface16aof the heat exchanger tube16simultaneously contacts the pair of detector elements124thereby shutting off, i.e., deactivating, the pumping device114represented by a zero voltage potential Vps0and thereby terminating expansion of the tubular outer surface16a.

By way of example only and not by way of limitation, for the first exemplary embodiment of the dimension sensor110, the controller136can be a conventional relay device as diagrammatically shown inFIGS. 7A and 7B. A skilled artisan would appreciate that exemplary controller136ofFIG. 7Arelates to the opened electrical circuit condition inFIG. 6Aand that the exemplary controller136ofFIG. 7Brelates to the closed electrical circuit condition toFIG. 6B.

A second exemplary embodiment of a dimension sensor210as illustrated inFIG. 8includes a body member222having a box-shaped configuration and a pair of detector elements224in a form of electrically conductive strips. A rectangular opening226extends through the body member222. Respective ones of the detector elements224extend along opposing edges240.

InFIGS. 9A and 9B, a third exemplary embodiment of a dimension sensor310includes a body member322configured in a shape of a fork and a pair of detector elements324. The forked-shared body member322includes pair of prongs322athat extend parallel to one another and are connected to a handle322b. The body member322defines a U-shaped opening326. Although not by way of limitation, the body member322is fabricated from an electrically non-conductive material such as plastic or resin and each one of the detector elements324is in a form of a pin. Each one of the detector elements324is fixedly connected to body member322such as by forcing fitting or injection molding. A respective one of the detector elements324extends through a respective one of the prongs322aof the body member322and is fabricated from an electrically conductive material.

A fourth exemplary embodiment of a dimension sensor410as illustrated inFIGS. 10-13B. The dimension sensor410includes a cylindrically-shaped body member422and a plurality of detector elements424. More specifically, the plurality of detector elements444includes three detector elements. The body member422defines a cylindrically-shaped opening426formed therethrough. Respective ones of the detector elements424are disposed equi-angularly apart from one another as viewed in cross-section about the opening426as represented by angle Y. Also, all three detector elements424are disposed in a common plane P as illustrated inFIG. 11.

As illustrated inFIG. 10, each one of the detector elements424are electrically connected to respective ones of lead wires132. As a result of this electrical arrangement, the heat exchanger tube16shown inFIG. 11is grounded. However, one of ordinary skill in the art would appreciate that the electrical arrangement can be made in any conventional manner without departing from the spirit and inventive concepts of the invention. By way of example only and not by way of limitation, one of the detector elements might be grounded in lieu of the heat exchanger tube while the remaining two detector elements are conductive.

The dimension sensor410includes a bushing442associated with each detector element424. Each bushing442is connected to and extends into the body member422. Each bushing is sized and adapted to be threadably engaged with the threaded screw shaft128. Each bushing is fabricated from an electrically non-conductive material such as resin, plastic or rubber. As a result, the body member442can be fabricated from an electrically conductive material such as metal.

InFIG. 12A, the heat exchanger tube16in its pre-expanded state fails to contact all three of the detector elements424simultaneously and, therefore, the opened electrical circuit condition exists thereby allowing expansion of the tubular outer surface since the pump device114is activated by the power supply26. InFIG. 12B, the heat exchanger tube16in its desired expanded state simultaneously contacts all three detector elements424thereby creating the closed electrical circuit condition thus shutting off the pumping device114and terminating expansion of the tubular outer surface of the heat exchanger tube. Although not by way of limitation, the controller136is in a form of a logic circuit. The logic circuit represented in diagrammatical form inFIG. 13Aindicates three OFF conditions because none of the three detector elements424are in contact with the tubular outer surface of the heat exchanger tube. The logic circuit represented in diagrammatical form inFIG. 13Bindicates three ON conditions because all of the three detector elements424are in contact with the tubular outer surface of the heat exchanger tube. A skilled artisan would appreciate that the logic circuit inFIG. 13Acorresponds to the controller136inFIG. 12Aand the logic circuit inFIG. 13Bcorresponds to the controller136inFIG. 12B.

A fifth exemplary embodiment of a dimension sensor510illustrated inFIGS. 14-16Bincludes a body member522and only one detector element524. The body member522is cylindrically shaped and includes a cylindrically shaped opening526. As shown inFIG. 16A, the heat exchanger tube being fabricated from an electrically conductive material is electrically connected with the electrical source138. The heat exchanger tube16in its pre-expanded state fails to contact the detector element524and, therefore, the opened electrical circuit condition exists thereby allowing expansion of the tubular outer surface since the pumping device114is activated by the power supply26. InFIG. 16B, the heat exchanger tube16in its desired expanded state contacts the detector element524thereby creating the closed electrical circuit condition thus shutting off the pumping device114and terminating expansion of the tubular outer surface of the heat exchanger tube.

A sixth embodiment of a dimension sensor610is illustrated inFIGS. 17A and 17B. A difference between the fifth exemplary embodiment of the dimension sensor510and the sixth exemplary embodiment610is that the only one detector element is a switch624. InFIG. 17A, the switch624is in the opened electrical circuit condition thereby allowing expansion of the tubular outer surface since the pump device is activated by the power supply. InFIG. 17B, the switch624is in the closed electrical circuit condition thus shutting off the pumping device114and terminating expansion of the tubular outer surface of the heat exchanger tube.

One of ordinary skill in the art would appreciate that for the sixth embodiment of the dimension sensor610as the heat exchanger tube is expanding, the expanding tube simultaneously contacts and displaces a detector portion624aof the switch624so that the switch624can move from the opened electrical circuit condition to the closed electrical circuit condition. Also, while the tube is expanding, the expanding tube simultaneously contacts and displaces the detector portion624aof the switch624. In contrast to the first through the fifth embodiments of the dimension sensor discussed above, in the pre-expanded state and while the tube is expanding, the detector element or detector elements and the heat exchanger tube are disposed apart from one another and, in the desired expanded state, the detector element or detector elements and the tube contact one another in order to deactive, i.e. shut off, the pumping device. In short, there is no movement of the detector element or detector elements with regard to the first through the fifth exemplary embodiments of the dimension sensor.

In summary, the dimension sensor of the present invention is used in conjunction with a tube and includes a body member and at least one detector element. The body member has an outer surface and an inner surface defining an opening sized to receive the tube. The at least one detector element is connected to the body member and has a detector portion extending into the opening generally in a radially inwardly direction relative to the tube received therein. The dimension sensor has an opened electrical circuit condition when the detector portion and the tube are disposed apart from one another and has a closed electrical circuit condition when the tube and the detector portion contact each other. Alternatively, the dimension sensor has an opened electrical circuit condition when the detector portion and the tube are disposed apart from one another and has a closed electrical circuit condition when the tube displaces the detector portion of the detector element a sufficient distance. A skilled artisan would appreciate that the sufficient distance is an amount of displacement required for the detector portion624ato move radially outwardly in order to produce a closed electrical circuit condition as typically occurs with any conventional damper-type switch.

A seventh exemplary embodiment of a dimension sensor710illustrated inFIGS. 18A and 18Bincludes a body member722in a form of U-shaped channel member and a detector element724in a form of a laser light detector assembly. The laser light detector assembly acting as a switch includes a plurality of laser light elements744and a CMOS panel746. The heat exchanger tube16is disposed in the body member722and between the laser light elements744and the CMOS panel746. As shown inFIG. 18A, when the heat exchanger tube16is in the pre-expanded state, some of the laser light beams illustrated as arrows W impinge upon the CMOS panel creating a voltage V+. As shown inFIG. 18B, when the heat exchanger tube16has been expanded to the desired expanded state, none of the laser beams W impinge upon the CMOS panel and thus no voltage is created as represented by V0. In view of this seventh exemplary embodiment of the dimension sensor710, a skilled artisan would appreciate that the voltage V+can be use with the controller136when the pumping device is activate to expand the tubular outer surface of the heat exchanger tube and that no voltage V0might be used to stop expansion of the heat exchanger tube when it expands to the desired expanded state.¶

In summary, the detector element and the tube form a first electrical circuit condition when the tube is in the pre-expanded state and form a second electrical circuit condition when the tube is in the desired expanded state. If the first electrical circuit condition is an opened electrical circuit condition, then the second electrical circuit condition is a closed electrical circuit condition. If the first electrical circuit condition is the closed electrical circuit condition, then the second electrical circuit condition is the opened electrical circuit condition.

An eighth embodiment of the present invention is method for stopping expansion of the tube expanding from a pre-expanded state to a desired expanded state. The tube is expanded from the pre-expanded state to the desired expanded state by a fluid pressurized by a pumping device. One step of the method includes actuating the pumping device to pressurize the fluid by an amount sufficient to cause the tube to expand from the pre-expanded state to the desired expanded state. Another step is providing a detector element operative in conjunction with the tube only in the desired expanded state such that when the tube expands to the desired expanded state, the pumping device deactivates thereby stopping expansion of the tube at the desired expanded state.

The present invention, may, however, be embodied in various different forms and should not be construed as limited to the exemplary embodiments set forth herein. Rather, these exemplary embodiments are provided so that this disclosure will be thorough and complete and will fully convey the scope of the present invention to those skilled in the art. For example, other conventional switches such as proximity switches might be used that are capable of performing the functions herein described. Also, the pumping device can be a hydraulic pump for pumping incompressible fluid such as water or a compressor for compressing compressible fluid such as air. Furthermore, one of ordinary skill in the art would appreciate that the drawing figures are exaggerated to illustrate the inventive concepts. Specifically, the relative sizes of the heat exchanger tubing in the pre-expanded state and in the desired expanded state are exaggerated for the purposes of easily conveying to the reader the concepts of the invention. Furthermore, the present invention could be used for expanding other types of tubes other than heat exchanger tubes regardless if such tubes are fabricated from electrically conductive or electrically non-conductive material. However, a skilled artisan would appreciate that every embodiment of the invention might not apply to every type of tube. Also, the arrangement of the electrical circuitry and components can be made in any conventional manner without departing from the spirit and scope of the invention.