Abstract:
An apparatus and method for connecting copper tubes are developed to facilitate welding operation in the refrigerating device. The new apparatus will reduce the poor welding rate so that it will effectively prevent clogging of the copper tubes and leaking the refrigerant. It also has merit to easily determine a suitable heating time while the copper tubes are welding. Thus, the rate of poor welding is reduced, as well as a method for connecting copper tubes by using the tube connecting apparatus.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to an apparatus and method for connecting copper tubes in a refrigerating system. More particularly, the apparatus facilitates to weld the copper tubes in the refrigeration device for preventing the clogging of the tubes and leaking the refrigerant due to the improper welding. While the copper tubes are welding, a suitable pre-heating and welding times are easily determined for reducing the rate of poor welding. 
         [0003]    2. Related Prior Art 
         [0004]    As generally known in the art, refrigeration devices have the following refrigeration cycle: the refrigerant flows through a compressor, a condenser, a capillary tube (a copper tube), an evaporator, and a suction tube. Then, the refrigerant again flows into the compressor. Refrigeration devices based on such a refrigeration cycle include refrigerators, air conditioners, etc. 
         [0005]    Such refrigeration devices require a connection between the capillary tube, which has a smaller diameter, and a tube having a larger diameter (e.g. evaporator suction tube). In this regard, it is crucial to connect the capillary tube to another tube without poor welding, which would otherwise cause the refrigerant to leak out or clog the capillary tube. 
         [0006]    A conventional capillary tube connecting device for accomplishing the above-mentioned task is disclosed in Korean Utility Model Application No. 20-1997-0035044 (filed Nov. 29, 1997), entitled “Refrigeration Machine Assembly Structure For Refrigerator”. As shown in  FIG. 3 , the outlet-side end of a capillary tube T and the inlet-side end of a suction tube S are inserted into the inlet-side and outlet-side ends of a refrigeration machine E, respectively, up to a predetermined length. Then, both ends of the refrigeration machine E are welded to the outer peripheries of the capillary tube T and the suction tube S, respectively, so that they are connected integrally. 
         [0007]    Another conventional capillary tube connecting device is disclosed in Korean Utility Model Application No. 20-1998-0018760 (filed Sep. 30, 1998), entitled “Refrigerator Dryer Easily Coupled to Capillary Tube”. As shown in  FIG. 1 , the section of the coupling portion  11 , to which a capillary tube  20  is coupled, is processed to have an inward slant so that, when the dryer  10  and the capillary tube  20  are coupled to each other, the melted welding material  30  flows through the resulting groove  13 . 
         [0008]      FIGS. 1   a  and  1   b  briefly show a configuration common to the above-mentioned conventional devices. Referring to  FIG. 1   a , a capillary tube  10 , which has a small outer diameter, is inserted into another tube  11 , which has a larger outer diameter (e.g. evaporator suction tube). Then, the coupling portions of both tubes  10  and  11  are welded and connected to each other by using filler metal  12 . However, this configuration has a problem in that, if there are errors between the outer diameter of the capillary tube  10  and the inner diameter of the other tube  11 , or if an inexperienced operator causes poor welding, both tubes  10  and  11  may not be welded completely and cause the refrigerant to leak out, as shown in  FIG. 1   b . Furthermore, in some cases, the filler metal  12  may flow into the other tube  11  and clog the capillary tube. 
         [0009]    Meanwhile, copper tubes are widely used as the piping of general air conditioners. The above-mentioned problem still exists when copper tubes are connected to each other. 
         [0010]    Therefore, it has been requested to provide technology for avoiding the above-mentioned problem when interconnecting capillary tubes having a smaller diameter or other types of copper tubes or copper-alloy tubes for refrigeration devices or air conditioners. Hereinafter, capillary tubes, copper tubes and copper-alloy tubes used for aforementioned connecting purposes are referred to as copper tubes as a whole. 
       SUMMARY OF THE INVENTION 
       [0011]    Accordingly, the present invention has been made to solve the above-mentioned problems occurring in the prior art, and the present invention provides a copper tube connecting apparatus adapted to facilitate a welding operation when a copper tube is connected to another tube regardless of the diameter of both tubes and the degree of skill of the operator, reduce the rate of poor welding, and prevent the copper tube from clogging or the refrigerant from leaking through the welded portion due to poor welding, as a method for connecting copper tubes by using the tube connecting apparatus. 
         [0012]    The present invention also provides a copper connecting apparatus adapted to facilitate a welding operation when a copper tube is connected to another tube regardless of the degree of skill of the operator, enable the operator to easily locate the inserted filler metal and recognize the accurate heating position, and guarantee rapid transfer of heat to the filler metal, as well as a method for connecting copper tubes by using the tube connecting apparatus. 
         [0013]    The present invention also provides a copper connecting apparatus adapted to inform the operator of a suitable welding heating time when a copper tube is connected to another tube so that reliable welding is guaranteed regardless of the degree of skill of the operator, as well as a method for connecting copper tubes by using the copper tube connecting apparatus. 
         [0014]    In accordance with an aspect of the present invention, there is provided a copper tube connecting apparatus including a body; a copper tube insertion hole formed on a first end of the body; and a connector hole formed to connect the copper tube insertion hole to a second tube insertion hole, wherein both ends of the connector hole have a diameter smaller than corresponding diameters of the copper tube insertion hole and the second tube insertion hole. 
         [0015]    The end of the connector hole near the copper tube insertion hole has a diameter smaller than the corresponding diameter of the copper tube insertion hole so that the resulting difference in diameter creates a stopping step between the connector hole and the copper tube insertion hole, and the end of the connector hole near the second tube insertion hole has a diameter smaller than the corresponding diameter of the second tube insertion hole so that the resulting difference in diameter creates a stopping step between the connector hole and the second tube insertion hole. Alternatively, the end of the connector hole near the second tube insertion hole has a diameter smaller than the corresponding diameter of the second tube insertion hole so that the resulting difference in diameter creates a stopping step between the connector hole and the second tube insertion hole, and the end of the connector hole near the copper tube insertion hole has a protrusion-type stopping step formed thereon. 
         [0016]    The copper tube connecting apparatus further includes a first filler metal receiving groove formed on the first end of the body, the copper tube insertion hole being formed on the first end, so as to surround the copper tube insertion hole; a second filler metal receiving groove formed on the second end of the body, the second tube insertion hole being formed on the second body, so as to surround the second tube insertion hole; and hollow filler metals mounted in the first and second filler metal receiving grooves, respectively. 
         [0017]    Preferably, the body of the copper tube connecting apparatus is formed as a hollow metallic cylinder, and the copper tube insertion hole, the second tube insertion hole, and the connector hole are formed coaxially. 
         [0018]    Preferably, the first filler metal receiving groove protrudes outward from the first end of the body, the copper tube insertion hole being formed on the first end, and the second filler metal receiving groove protrudes outward from the second end of the body, the second tube insertion hole being formed on the second end. The first and second filler metal receiving grooves are displaced inward from both ends of the body by a predetermined distance L, respectively. 
         [0019]    In accordance with another aspect of the present invention, there is provided a copper tube connecting apparatus including a body; a copper tube insertion hole formed on a first end of the body; a second tube insertion hole formed on a second end of the body; a connector hole formed to connect the copper tube insertion hole to the second tube insertion hole; a first filler metal receiving groove formed on the first end of the body, the copper tube insertion hole being formed on the first end, so as to surround the copper tube insertion hole; a second filler metal receiving groove formed on the second end of the body, the second tube insertion hole being formed on the second end, so as to surround the second tube insertion hole; at least one first through-hole extending through the first end of the body to the first filler metal receiving groove; and at least one second through-hole extending through the second end of the body to the second filler metal receiving groove. 
         [0020]    The first and second through-holes extend in a radial direction from the first and second filler metal receiving grooves to an outer surface of the body, respectively. 
         [0021]    Both ends of the connector hole have a diameter smaller than corresponding diameters of the copper tube insertion hole and the second tube insertion hole. The end of the connector hole near the copper tube insertion hole has a protrusion-type stopping step formed thereon, and the end of the connector hole near the second tube insertion hole has a diameter smaller than the corresponding diameter of the second tube insertion hole so that the resulting difference in diameter creates a stopping step between the connector hole and the second tube insertion hole. 
         [0022]    Preferably, the first filler metal receiving groove protrudes outward from the first end of the body, the copper tube insertion hole being formed on the first end, and the second filler metal receiving groove protrudes outward from the second end of the body, the second tube insertion hole being formed on the second end. The first and second filler metal receiving grooves are displaced inward from both ends of the body by a predetermined distance L, respectively. 
         [0023]    In accordance with another aspect of the present invention, there is provided a method for connecting copper tubes by using a copper tube connecting apparatus having the above-mentioned features, the method including the steps of inserting the copper tube and the second tube into the copper tube insertion hole and the second tube insertion hole, respectively; moving the copper tube and the second tube to both ends of the connector hole, respectively; and heating the first and second ends of the body, the first and second filler metal receiving grooves being formed on the first and second ends of the body, respectively, to melt the first and second filler metal and conduct welding. 
         [0024]    When through-holes have been formed, the method further includes a step of determining whether or not heating is appropriate with reference to conditions of the melted first and second filler metals flowing out through the first and second through-holes. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0025]      FIGS. 1   a  and  1   b  illustrate a method for connecting copper tubes according to the prior art. 
           [0026]      FIG. 2  shows the construction of a copper tube connecting apparatus according to a first embodiment of the present invention. 
           [0027]      FIG. 3  illustrates the operation of the copper tube connecting apparatus according to the first embodiment of the present invention. 
           [0028]      FIG. 4  shows the construction of a copper tube connecting apparatus according to a second embodiment of the present invention. 
           [0029]      FIG. 5  is a longitudinal sectional view of the copper tube connecting apparatus according to the second embodiment of the present invention. 
           [0030]      FIG. 6  shows the construction of a copper tube connecting apparatus according to a third embodiment of the present invention. 
           [0031]      FIG. 7  shows the construction of a copper tube connecting apparatus according to a fourth embodiment of the present invention. 
           [0032]      FIG. 8  shows the construction of a copper tube connecting apparatus according to a fifth embodiment of the present invention. 
           [0033]      FIG. 9  shows the construction of a copper tube connecting apparatus according to a sixth embodiment of the present invention. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0034]    Hereinafter, an exemplary embodiment of the present invention will be described with reference to the accompanying drawings. In the following description and drawings, the same reference numerals are used to designate the same or similar components, and so repetition of the description on the same or similar components will be omitted. 
         [0035]      FIG. 2  shows the construction of a copper tube connecting apparatus according to a first embodiment of the present invention, and  FIG. 3  illustrates the operation of the copper tube connecting apparatus according to the first embodiment of the present invention. 
         [0036]    Referring to  FIG. 2 , the copper tube connecting apparatus includes a hollow body  200 , which has a hollow portion so that a copper tube can be inserted therein; a copper tube insertion hole  230 , which has a first diameter corresponding to the diameter of a copper tube  100 , formed on the first end of the body  200 ; a second tube insertion hole  240 , which has a second diameter corresponding to the diameter of a second tube  110  to be connected to the copper tube  100 , formed on the second end of the body  200 ; and a connector hole  250  formed between the copper tube insertion hole  230  and the second tube insertion hole  240  so that both tubes  230  and  240  communication with each other. As such, the connector hole  250  defines a hollow portion inside the copper tube connecting apparatus. As an alternative to the construction shown in  FIG. 2 , the copper tube insertion hole  230  and the second tube insertion hole  240  may have different diameters. 
         [0037]    A protrusion-type first stopping step  260  is formed between the inner end of the copper tube insertion hole  230  and one end of the connector hole  250 , and indicates the limit of insertion of the copper tube  100 . In addition, the difference in diameter between the second tube insertion hole  240  and the connector hole  250  creates a second stopping step  270  between the inner end of the second tube insertion hole  240  and the other end of the connector hole  250 , and the second stopping step  270  indicates the limit of insertion of the second tube  110 . The protrusion-type first stopping step  260  preferably has a minimum size so that it does not interfere with the flow of fluid between the copper tube  100  and the connector hole  250 . The diameter of the connector hole  250  must have a value between the first diameter of the copper tube insertion hole  230  and the second diameter of the second tube insertion hole  240 . The connector hole  250  is shown in  FIG. 2  to have a diameter equal to the first diameter of the copper tube insertion hole  230 . 
         [0038]    The body  200  has a first filler metal receiving groove  210  formed on the first end, on which the copper tube insertion hole  230  is formed, so as to surround the copper tube insertion hole  230 . Furthermore, the body  200  has a second filler metal receiving groove  220  formed on the second end, on which the second tube insertion hole  240  is formed, so as to surround the second tube insertion hole  240 . As a result, hollow (or ring-shaped) first and second filler metal  212  and  222  can be mounted in the first and second filler metal receiving grooves  210  and  220 , respectively. 
         [0039]    The copper tube connecting apparatus of the above-mentioned structure is used to connect the copper tube  100  to the second tube  110  in the following manner: the copper tube  100  is inserted until it is stopped by the first stopping step  260  on the inner end of the copper tube insertion hole  230 , and the second tube  110  is inserted until it is stopped by the second stopping step  270  on the inner end of the second tube insertion hole  240 . A heating device (e.g. torch) is used to heat both ends of the body  200  so that the filler metals  212  and  222  on both ends melt. As a result, the copper tube  100  and the second tube  110  are welded to the body  200 , respectively. 
         [0040]    Particularly, heating of the ends of the body  200  melts the second filler metal  222 , which then flows between the inner surface of the body  200  and the outer surface of the second tube  110  during the course of welding. The contact between the end of the second tube  110  and the second stopping step  270  formed on the inner end of the second tube insertion hole  240  prevents the second filler metal  222  from proceeding further. This avoids any possibility that the second filler metal  222  may clog the interior of the second tube  110 . In the case of the welding region where the body  200  of the copper tube connecting apparatus, the copper tube  100 , and the first filler metal  212  join one another, the contact between the end of the copper tube  110  and the first stopping step  260  formed on the inner end of the copper tube insertion hole  230  similarly prevents the first filler metal  212  from proceeding further. This avoids any possibility that the first filler metal  212  may clog the interior of the copper tube  100 . 
         [0041]    The body  200  of the copper tube connecting apparatus preferably has a cylindrical shape, and is made of a metallic material (e.g. copper, copper alloy), but the shape and material of the body  200  may be varied as desired without limiting the scope of the present invention. In addition, those skilled in the art can easily understand that, although it has been assumed in the above description of an embodiment of the present invention that the copper tube insertion hole  230 , the second tube insertion hole  240 , and the connector hole  250  are coaxially formed, the copper tube insertion hole  230  and the second tube insertion hole  240  may be formed on different axes and then connected to each other via the connector hole  250 . This can also be said with regard to the following descriptions of other embodiments of the present invention. 
         [0042]      FIG. 4  shows the construction of a copper tube connecting apparatus according to a second embodiment of the present invention. 
         [0043]    The overall construction of the copper tube connecting apparatus according to the second embodiment is the same as that according to the first embodiment, except for through-holes for allowing the filler metal to leak. Particularly, the copper tube connecting apparatus according to the second embodiment is characterized in that it includes at least one first through-hole extending through the first end of the body of the apparatus to a first filler metal receiving groove, and at least one second through-hole extending through the second end of the body to the second filler metal receiving groove. The first and second through-holes extend in the radial direction from the first and second filler metal receiving grooves to the outer surface of the body. 
         [0044]    The copper tube connecting apparatus according to the second embodiment will be described in more detail with reference to  FIG. 4 . The apparatus has at least one, preferably two, through-holes formed between the outer surface of the body  200  and the inner surface of the first and second filler metal receiving grooves  212  and  222 , respectively.  FIG. 4  shows two first through-holes  214  extending from the outer surface of the first end of the body  200  to the inner surface of the first filler metal receiving groove  212  upward and downward, respectively, and two second through-holes  224  extending from the outer surface of the second end of the body  200  to the inner surface of the second filler metal receiving groove  222  upward and downward, respectively. Those skilled in the art can understand that more than two through-holes may be formed for each end of the body  200 . 
         [0045]      FIG. 5  is a longitudinal sectional view of the copper tube connecting apparatus according to the second embodiment of the present invention, and shows two through-holes  212  formed on the first end of the body  200  of the apparatus upward and downward, respectively. 
         [0046]    When the copper tube connecting apparatus is used to connect copper tubes, both ends of the body  200  of the apparatus are heated to melt the filler metals  212  and  222 , which then flow out of the body  200  through the first and second through-holes  214  and  224  formed on both ends of the body  200  due to the capillary phenomenon. This makes it possible to determine whether heating suitable or optimized for welding is being conducted with reference to conditions of the filler metals  212  and  222  flowing out through the through-holes  212  and  224 . 
         [0047]      FIG. 6  shows the construction of a copper tube connecting apparatus according to a third embodiment of the present invention. 
         [0048]    The construction of the copper tube connecting apparatus according to the third embodiment of the present is the same as that according to the first embodiment, except that the first stopping step  265  has the shape of a stepped portion exactly like the second stopping step  270 . 
         [0049]    Particularly, the diameter of both ends of the connector hole  250  of the copper tube connecting apparatus shown in  FIG. 6  may have any value smaller than the first diameter of the copper tube insertion hole  230  and the second diameter of the second tube insertion hole  240 . In other words, the entire connector hole  250  need not have the same diameter, and both ends of the connector hole  250  may have different diameters, as long as the size and shape of the connector hole  250  do not interfere with the flow of fluid between the copper tube  100  and the second tube  110 . 
         [0050]    The method for connecting the copper tube  100  to the second tube  110  according to the third embodiment is the same as in the first embodiment. 
         [0051]      FIG. 7  shows the construction of a copper tube connecting apparatus according to a fourth embodiment of the present invention. 
         [0052]    The copper tube connecting apparatus shown in  FIG. 7  combines the characteristics of the third embodiment (i.e. the first stopping step  265  has the shape of a stepped portion exactly like the second stopping step  270 ) with those of the second embodiment (i.e. through-holes  214  and  224  for allowing filler metals  212  and  222  to leak). The remaining components and the connecting method will be obvious to those skilled in the art, and detailed description thereof will be omitted herein. 
         [0053]      FIG. 8  shows the construction of a copper tube connecting apparatus according to a fifth embodiment of the present invention. 
         [0054]    Referring to  FIG. 8 , the apparatus has a first filler metal receiving groove  211  protruding outward from the first end of the body  200 , on which the copper tube insertion hole  230  is formed, and a second filler metal receiving groove  221  protruding outward from the second end, on which the second tube insertion hole  240  is formed, so that hollow filler metals  213  and  223  can be mounted in a shape corresponding to that of the filler metal receiving grooves  211  and  221 . 
         [0055]    Therefore, the body  200  of the copper tube connecting apparatus has protrusions, particularly filler metal receiving groove protrusions  215  and  225 , in regions where the first and second filler metal receiving grooves  211  and  221  are formed. The filler metal receiving groove protrusions  215  and  225  must be shaped to increase the heat transfer area as much as possible so that heat applied to the copper tube is quickly transmitted to the filler metals  213  and  223  via the surface of the copper tube. Preferably, the filler metal receiving groove protrusions  215  and  225  have an approximately V-shaped or U-shaped sectional structure. 
         [0056]    Although the first and second filler metal receiving grooves  211  and  221  are shown in  FIG. 8  to be displaced inward from both ends of the body by a predetermined distance L, the position is not limited to that. Ring-shaped welding rods may be used as the first and second filler metals  213  and  223 , which may be inserted either during or after the process of forging the copper tube. 
         [0057]    A process of connecting copper tubes by using the copper tube connecting apparatus, which has the above-mentioned construction, as well as its operation, will now be described with reference to  FIG. 8 , which is a sectional view showing a state after insertion of the copper tube. 
         [0058]    Referring to  FIG. 8 , the copper tube connecting apparatus according to the fifth embodiment of the present invention is used to connect two copper tubes  100  and  110  in the following manner: the first copper tube  100  is inserted until it is stopped by the stopping step  265  on the inner end of the copper tube insertion hole  230 , and the second copper tube  110  is inserted until it is stopped by the stopping step  270  on the inner end of the second tube insertion hole  240 . Then, a heating device (e.g. torch, high-frequency heater) is used to heat the filler metal receiving groove protrusions  215  and  225  on both ends of the body  200  so that filler metals  213  and  223  on both ends are melted. The copper tube  100 , the copper tube connecting apparatus body  200 , and the second copper tube  110  are welded to one another in this manner. 
         [0059]    By using the copper tube connecting apparatus, the position of inserted filler metal is easily recognized from the filler metal receiving groove protrusions  215  and  225  of the body  200  of the apparatus, and the heating position is accurately grasped. This facilitates the welding process regardless of the degree of skill of the operator. In addition, the filler metal receiving groove protrusions  215  and  225  correspond to radial extensions of the body  200  of the copper tube connecting apparatus. This means that the surface area is increased both locally and globally, and that the substantial heat transfer area is enlarged. 
         [0060]    Therefore, heat applied to the filler metal receiving groove protrusions  215  and  225  with an enlarged heat transfer area is quickly transferred to the filler metals  213  and  223  via the surface of the copper tube. This guarantees an accurate welding operation and prevents poor welding. 
         [0061]    Although it has been assumed with reference to  FIG. 8  that the thickness of the solid portion of the copper tube connecting apparatus varies in the axial direction (i.e. the thickness of the solid portion of the connector hole differs from that of other parts), the entire solid portion of the copper tube may have the same thickness. Particularly, the copper tube connecting apparatus may be processed along the axial direction by forging or pressing so that respective parts are enlarged and reduced while the entire solid portion retains the same thickness. As a result, the copper tube is stopped by the central, enlarged part and is inserted no longer. This replaces the stopping steps  265  and  270  according to the above-mentioned embodiments. 
         [0062]      FIG. 9  shows the construction of a copper tube connecting apparatus according to a sixth embodiment of the present invention. 
         [0063]    The construction of the copper tube connecting apparatus according to the sixth embodiment is the same as that according to the fifth embodiment shown in  FIG. 8 , except that additional through-holes  217  and  227  for allowing the filler metals  213  and  223  to leak are provided. Therefore, the structural characteristics and the operating method will be obvious to those skilled in the art, and detailed description thereof will be omitted herein. 
         [0064]    As mentioned above, the copper tube connecting apparatus and the method for connecting copper tubes by using the tube connecting apparatus according to the present invention have the following advantages: when a copper tube is connected to another tube, the welding process is made easy regardless of the diameter of both tubes and the degree of skill of the operator; and the rate of poor welding is reduced to prevent the copper tube from clogging or the refrigerant from leaking through the welded portion due to poor welding. 
         [0065]    In addition, when a copper tube is connected to another tube, the welding operation is made easy regardless of the degree of skill of the operator, and the operator can easily locate the inserted filler metals and recognize the accurate heating position. This guarantees rapid transfer of heat to the filler metal. 
         [0066]    The apparatus and method inform the operator of a suitable welding heating time when a copper tube is connected to another tube so that reliable welding is guaranteed regardless of the degree of skill of the operator. 
         [0067]    Furthermore, the apparatus and method enable the operator to accurately control the heating position and heating time when copper tubes are connected. This avoids incomplete welding due to insufficient heating time and prevents the copper tubes or the copper tube connecting apparatus from deforming due to excessive heating. As a result, the rate of poor welding decreases. 
         [0068]    The apparatus and method can also prevent the operating fluid (e.g. refrigerant, water) of a refrigeration device or an air conditioner from leaking due to poor welding. This improves the reliability of the refrigeration device or the air conditioner. 
         [0069]    Although an exemplary embodiment of the present invention has been described for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.