Patent Publication Number: US-7708318-B2

Title: Tube to hose coupling

Description:
TECHNICAL FIELD 
     This invention relates to crimp-type tube-to-hose couplings and methods of making this type of coupling, with particular adaptation for vehicular air conditioning systems and similar sealed fluid conducting systems. 
     BACKGROUND ART 
     In every vehicular air conditioning system there is a plurality of sections of flexible hose. These hose sections connect in a single system, with various system components including a compressor, condenser, evaporator and other system components. 
     A coupling is required at each hose end to allow the hose to be secured to the various components between which it extends. The coupling will usually include the end portion of a rigid tube which is secured to the flexible hose. The tube will include a flare fitting or other arrangement for connection to a system component. 
     The usual coupling for securing the flexible hose to the rigid tube is to utilize a connector portion with two concentric cylindrical walls spaced from one another by approximately the thickness of the hose. One of these concentric walls includes a radially extending flange securing it to the other. The inner concentric wall includes a throughbore to allow for fluid passage between the rigid tube and hose. 
     The hose is inserted between the inner concentric cylinder and the outer concentric cylinder. The outer cylindrical wall is crimped (plastically deformed) onto the hose and the inner concentric cylinder to form a fluid tight joint. 
     A typical coupling of this type is shown in U.S. Pat. No. 5,044,671, assigned to TI Group Automotive Systems, LLC. There, the inner cylindrical wall is formed by the outer surface of the rigid tube. The outer concentric wall is formed by a sleeve that includes a radial flange extending radially inward and joined to the inner concentric tube. The inner concentric wall, or tube, is provided with annular locking ribs and the radial flange is the swaged or crimped onto the locking ribs of the tube. 
     Alternatively, the tube may be upset, or otherwise provided with a radial shoulder, immediately adjacent and contiguous with both sides of the radial flange of the sleeve to provide an axial stop in both directions. In each case, the axial position of the two coupling components, (i.e., the sleeve and the tube) is fixed to define an annular space to receive the hose. This type of coupling configuration requires a number of metal forming operations on the end of the tube and a separately formed sleeve. 
     A more recent development in tube to house couplings is described in U.S. Pat. No. 5,417,461 also assigned to TI Group Automotive Systems, LLC. Here, the outer cylindrical crimp wall is integral with the rigid tube. The inner coupling wall is defined by a separate insert fitted with a seal. The tube is preformed to include a circumferential seat to mate with the installed seal on the insert. 
     Another similar coupling is described in U.S. Pat. No. 5,961,157, assigned to Manuli Auto France. This patent discloses a coupling in which the outer cylindrical crimp wall is also formed by the rigid tube. The inner cylindrical wall is defined by an insert assembled into the tube end to define the hose receiving annulus. The insert is also fitted with a seal. In this design, a forward tubular portion of the insert, fitted with a seal, is forced into the unexpanded inner diameter end portion of the rigid tube. Necessarily the diameter of the throughbore of the insert is smaller than the bore of the tube. 
     The insert in each of the foregoing designs typically is made from a rigid material (such as aluminum or steel) having sufficient strength to resist the crimping forces necessary to create a seal between the insert and the flexible hose. These materials and associated manufacturing methods are costly. One solution would be to reduce the crimping force and fit the insert with a seal member such as the O-ring employed between the rigid tube and the insert. Such a seal member would create a seal between the outer surface of the insert and the inner diameter of the flexible hose. The required groove to retain the seal would require an increase in wall thickness of the insert and therefore a reduced throughbore diameter. Such a reduced throughbore has negative effects on the performance of the coupling with regard to fluid flow since it defines a restrictive orifice in the fluid system. 
     The present invention provides a coupling device and method of making a connection between a rigid tube and flexible hose which avoids undue restriction of the flow passage and simplifies manufacturing processes required to create the coupling. 
     SUMMARY OF THE INVENTION 
     The present invention provides a simple, economical and leak-tight construction of crimp-type tube-to-hose coupling. The coupling of the invention includes an insert sealed at one end portion to the tube and sealed at its opposite end portion to the flexible hose leg a polymeric layer bonded between the insert and the flexible hose. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exploded perspective view prior to assembly, showing the components of a tube-to-hose coupling embodying the principles of the present invention. 
         FIG. 2  is a side view, partially in section, of the assembled coupling of  FIG. 1 . 
         FIG. 3  is a side view, partially in section, of a modified form of coupling embodying principles of the present invention. 
         FIG. 4  is a partial cross-sectional view of a modified form of tube-to-hose coupling embodying the principles of the present invention. 
         FIG. 5  is a side sectional view of a component of the tube-to-hose coupling of  FIG. 4 . 
     
    
    
     DETAILED DESCRIPTION OF ILLUSTRATED EMBODIMENTS 
     Referring to  FIGS. 1 and 2 , the disclosed coupling, with components manufactured and assembled as described below, forms a leak-tight joint having many fluid conveying applications. It is particularly suited for use in vehicular air conditioning systems. 
     Referring to  FIGS. 1 and 2 , coupling  100  includes rigid hollow tube  102  connected to hollow flexible hose  104  by elongate hollow insert  106 . An end (not shown) of the tube  102  is configured to connect to a system component. It may include, for example, a flare shape and support a rotatable nut for attachment to a threaded seat element formed on the system component. The opposite end (not shown) of hose  104  may connect to another tube or other form of coupling. 
     Tube  102  is made from steel or aluminum alloy. A suitable alloy is 3000 series aluminum alloy. It defines internal bore  103 . 
     Referring to  FIG. 1 , an end portion of the tube is formed to define a first radially enlarged sleeve portion  110  and a second or intermediate radially enlarged sleeve portion  114 . First, radially enlarged sleeve portion  110  is sized to receive the outer surface of flexible hose  104 . Intermediate radially enlarged sleeve portion  114  is sized to receive a portion of the insert  106  as described below. 
     Radially directed annular wall  113  extends between first radially enlarged sleeve portion  110  and intermediate radially enlarged sleeve portion  114 . It defines a shoulder that limits axial insertion of hose  104 . 
     Radially directed annular wall  115  extends between intermediate radially enlarged sleeve portion  114  and the internal bore  103  of tube  102 . It defines a shoulder that limits axial insertion of insert  106  into tube  102 . 
     The insert  106  has an axial length that is somewhat longer than the axial distance between the shoulder defined by radially annular wall  115  and the free end of the tube  102 . It defines throughbore  116  which provides a fluid path between the internal bore of tube  103  and the internal bore  105  of the hose  104 . The cross sectional area of bore  116  is about seventy percent (70%) of the cross sectional area of bore  105  of hose  104 . 
     The insert  106  is made from reinforced thermoplastic. A suitable material for the insert is polyamide 6 (Nylon 6). A suitable reinforcing material for the insert is glass fiber with a filling rate of about ten percent (10%) by weight. It could also be made of metal such as aluminum and coated with a layer of polymeric material such as polyamide 6 as discussed below. 
     An end portion of insert  106  includes enlarged cylindrical collar  120 . Collar  120  has a diameter to be snugly received in intermediate radially enlarged portion  114  of tube  102  in piloting relation. Outer axial surface  122  is provided with a radial groove in which is positioned sealing member in the form of an O-ring seal  124  having an outer diameter greater than that of axial surface  122 . O-ring seal  124  seals against the inner surface of intermediate radially enlarged sleeve portion  114  when collar  120  is inserted into intermediate radially enlarged sleeve portion  114 . The end of collar  120  abuts shoulder  115  to axially position the insert  106 . 
     The other end portion of insert  106  defines cylindrical barrel  108 , and includes an outer cylindrical surface  126  having a diameter somewhat larger than the internal bore  105  of hose  104 . It is sized to be received in bore  105  of hose  104  with minimal axial insertion force. 
     Hose  104  is flexible, made of multiple extruded layers and includes internal bore  105 . The end portion of hose  104  defines an insert receiving portion. 
     The hose  104  has an inner layer  109  of thermoplastic or thermoplastic blend material suitable for vehicular air conditioning systems bonded to the adjacent radially outward layer of the hose. It has a thickness of approximately 0.2 mm. The inner layer material is chosen for its resistance to compressor lubricating oils such as polyalkylene glycol (PAG) or polyol ester (POE), resistance to diffusion of refrigerants such as HFC134a or HFC152a, resistance to the refrigerants in terms of chemical extraction, and capable of performing in a temperature range of −30 to +150° C. 
     A suitable material for inner layer  109  is polyamide 6-6 or a blend of polyamide 6-6 and IIR (Butal) elastomer. This material also well suited for use in the present invention, since the thermoplastic material can be fused to form a strong and leak-tight joint using frictional surface melting of the material. 
     The coupling  100  of  FIGS. 1 and 2  is assembled by axially inserting barrel  108  of insert  106  into the bore  105  of hose  104 . Since the outer cylindrical surface  126  of cylindrical barrel  108  has a diameter larger than the bore  105  of hose  104 , these surfaces are in contact with a small radially inward force imparted to the barrel  108  by the hose  104 . 
     The insert is rotated about its axis or vibrated axially at a rate to generate heat during insertion. The friction from the spinning or vibratory contact causes surface melting of the inner layer  109  and the outer cylindrical surface  126  of the barrel  108  of insert  106  which results in a fusing of the inner layer  109  of hose  104  to the outer cylindrical surface  126  of barrel  108 . 
     It is contemplated that other methods accomplishing a bond of the polymeric layer to the adjacent surface. These include induction heating, use of a solvent or of an adhesive. 
     Once fully inserted, insert  106  extends from free end of hose  104  about the same axial length as the axial spacing between radially annular wall  113  and radially annular wall  115 . The sub-assembly of hose  104  and insert  106  is then connected to tube  102 . Collar  120  with O-ring seal  124  is inserted into the end of the tube  102  until the collar abuts the shoulder defined by radial annular wall  115 . This positions the end of hose  104  within radially enlarged sleeve portion  110  with free end of the hose abutting radially annular wall  113 . 
     The intermediate radially enlarged portion  114  of tube  102  is crimped radially inward adjacent the collar  120  to collapse the portion  114  onto the outer axial surface  122  collar  120 . The crimp  128  captures collar  120  to secure the insert  106  to the tube. Seal member  124  is compressed against the inner surface of intermediate radially enlarged portion  114  and collar  120  to create a fluid tight seal. 
     The radially enlarged sleeve portion  110  which overlies the end portion of hose  104  is crimped or plastically deformed radially inwardly onto the hose forming crimp  130 . The annular wall of the hose is compressed between the barrel  108  of insert  104  and the radially enlarged sleeve portion  110  to mechanically secure the hose to the insert. The crimping operations may be done in sequence or simultaneously. 
     The insert  106  is sealed relative to rigid tube  102  by O-ring seal  124 . The insert  106  is sealed to the inner surface of hose  104  by the bond created by the surface melting of inner polymeric layer  109 . The layer  109  is bonded to the outer cylindrical surface  126  of insert  106  on assembly. 
     The fluid seal arrangement of the embodiment of  FIGS. 1 and 2  is suitable for incorporation in the various tube-to-hose couplings disclosed in the previously identified United States patents. In such arrangements, the flexible hose would include an inner layer such as the polyamide layer  109 . 
     Another coupling exemplary of the principles of the present invention is shown in  FIG. 3 . This embodiment is similar to the embodiment of  FIGS. 1 and 2  with the exception that the end of the rigid tube is provided with a separate crimp sleeve component secured to the end portion of the rigid tube. Consistent with the principles of the present invention, a polymeric thermoplastic layer of the flexible hose is bonded between the outer cylindrical surface of the hose. 
     Referring to  FIG. 3 , coupling  200  includes rigid hollow tube  202  connected to hollow flexible hose  204  by elongate hollow insert  206 . An end (not shown) of the tube  202  is configured to connect to a system component. It may include, for example, a flare shape and support a rotatable nut for attachment to a threaded seat element formed on the system component. The opposite end (not shown) of hose  204  may connect to another tube or other form of coupling. Tube  202  is made from steel or aluminum alloy. A suitable alloy is 3000 series aluminum alloy. It defines internal bore  203 . 
     Referring to  FIG. 3 , an end portion of the tube is formed to define a radially enlarged portion  214  sized to receive a portion of the insert  206  as described below. Sleeve portion  214  is formed to define spaced radial outward flanges  211  and  212 . These flanges define an annular channel. 
     A separate generally cylindrical crimp sleeve  213  extends axially from the end portion  207 . It includes a cylindrical sleeve portion  210  and an annular radial wall  217 . Radial wall  217  is champed within the channel formed between radial flanges  211  and  212  to secure the crimp sleeve  213  to tube end. The sleeve portion  210  is sized to receive the outer surface of the flexible hose  204 . Wall  217  and radial flange  211  limit axial movement of the hose relative to tube  202 . 
     Conical wall  215  extends between radially enlarged sleeve portion  214  and the internal bore  203  of tube  202 . It defines a shoulder that limits axial insertion of insert  206  into tube  202 . 
     The insert  206  has an axial length that is somewhat longer than the axial distance between the shoulder defined by conical wall  215  and the free end of the sleeve  210 . Insert  206  defines throughbore  216  which provides a fluid path between the internal bore  203  of tube  202  and the internal bore  205  of the hose  204 . The cross sectional area of bore  216  is about seventy percent (70%) of the cross sectional area of bore  205  of hose  204 . 
     The insert  206  is made from reinforced thermoplastic. A suitable material for the insert is polyamide 6 (Nylon 6). A suitable reinforcing material for the insert is glass fiber with a filling rate of about ten percent (10%) by weight. It could also be made of metal such as aluminum coated with an outer layer of polymeric material such as polyamide 6 as discussed below. 
     One end portion of insert  206  includes enlarged cylindrical collar  220 . Collar  220  has a diameter to be snugly received in radially enlarged portion  214  of tube  202  in piloting relation. Outer axial surface  222  is provided with a relief  223  on which is positioned a sealing member in the form of an O-ring seal  224  having an outer diameter greater than that of axial surface  222 . O-ring seal  224  seals against the inner surface of radially enlarged sleeve portion  214  when collar  220  is inserted into radially enlarged sleeve portion  214 . The end of collar  220  abuts conical wall  215  to axially position the insert. 
     The other end portion of insert  206  defines barrel  208 , with an outer cylindrical surface  226  having a diameter somewhat larger than the internal bore  205  of hose  204 . It is sized to be received in bore  205  of hose  204  with minimal axial insertion force. 
     Hose  204  is flexible, made of multiple extruded layers and includes internal bore  205 . The end portion of hose  204  defines an insert receiving portion. 
     The hose  204  has an inner layer  209  of thermoplastic or thermoplastic blend material suitable for vehicular air conditioning systems bonded to the adjacent radially outward layer of the hose. It has a thickness of approximately 0.2 mm. The inner layer material is chosen for its resistance to compressor lubricating oils such as polyalkylene glycol (PAG) or polyol ester (POE), resistance to diffusion of refrigerants such as HFC134a or HFC152a, resistance to the refrigerants in terms of chemical extraction, and capable of performing in a temperature range of −30 to +150° C. 
     A suitable material for inner layer  209  is polyamide 6-6 or a blend of polyamide 6-6 and IIR (Butal) elastomer. This material also well suited for use in the present invention, since the thermoplastic material can be fused to form a strong and leak-tight joint using frictional surface melting of the hose material. 
     The coupling  200  of  FIG. 3  is assembled by axially inserting cylindrical barrel  208  of insert  206  into the bore  205  of hose  204 . Since the outer cylindrical surface  226  of barrel  208  has a diameter larger than the bore  205  of hose  204 , these surfaces are in contact. 
     The insert is rotated about its axis or vibrated axially at a rate to generate heat during insertion. The friction from the spinning or vibratory contact causes surface melting of the inner layer  209  and the outer cylindrical surface  226  of the barrel  208  of insert  206  which results in a fusing of the inner layer  209  of hose  204  to the outer cylindrical surface  226  of barrel  208 . 
     It is contemplated that other methods accomplishing a bond of the polymeric layer to the adjacent surface. These include induction heating, use of a solvent or of an adhesive. 
     As inserted, the insert  206  extends from free end of hose  204  about the same axial length as the distance from conical wall  215  to the radial flange  211  formed on the free end of tube  202 . The sub-assembly of hose  204  and insert  206  is then connected to tube  202 . Collar  220  with O-ring seal  224  is inserted into the end of the tube  202  until the relieved portion of collar  220  with O-ring  224  abuts the shoulder defined by conical wall  215 . This positions the end of hose  204  within radially enlarged sleeve portion  210  with the free end of the hose abutting radial wall  217  of crimp sleeve  213  and radial flange  211  of tube  202 . 
     The radial flange  212  of tube  202  is plastically deformed or crimped radially inward adjacent the collar  220  to collapse the portion  214  onto the collar  220 . The crimp  228  captures collar  220  to secure the insert  206  to the tube. Seal  224  is compressed against the conical wall  215  and relief  223  to create a fluid tight seal. 
     The separate crimp sleeve  213  which overlies the end of hose  204  is crimped or plastically deformed radially inwardly onto the hose forming crimp  230 . The annular wall of the hose is compressed between the outer cylindrical surface  226  of insert  204  and the crimp sleeve  213  to mechanically secure the hose to the insert. The crimping operation may be done in sequence or simultaneously. 
     The insert  206  is sealed relative to rigid tube  202  by O-ring seal  224 . The insert  206  is sealed to the inner surface of hose  204  by the bond created by the surface melting of inner polymeric layer  209 . This bond exists between the inner layer  209  of hose  204  and outer cylindrical surface  226  of barrel  208 . 
     A further alternative form of tube-to-hose coupling  300  embodying principles of the present invention is disclosed in  FIGS. 4 and 5 . Here, a tube  302  having bore  303  is secured to flexible hose  304  having internal bore  305  with an elongate hollow insert  306  consistent with the principles of the present invention. The outer surface of the insert  306  includes a bonded polymeric layer that seals to the tube  302  and to flexible hose  304 . 
     Referring to  FIGS. 4 and 5 , coupling  300  includes rigid hollow tube  302  connected to hollow flexible hose  304  by elongate hollow insert  306 . An end (not shown) of the tube  302  is configured to connect to a system component also as described with respect to earlier embodiments. Similarly, the opposite end (not shown) of base  304  may connect to another tube or other form of coupling. Tube  302  is made from steel or aluminum alloy as previously described with respect to earlier embodiments. It defines internal bore  303 . 
     Referring to  FIG. 4 , free end portion of the tube is formed to define a first radially enlarged sleeve portion  310  and a second or intermediate radially enlarged sleeve portion  314 . Sleeve portion  310  is sized to receive the outer surface of flexible hose  304 . Intermediate radially enlarged sleeve portion  314  is sized to receive a portion of the insert  306  as described below. 
     Radially directed annular wall  313  extends between first radially enlarged sleeve portion  310  and intermediate radially enlarged sleeve portion  314 . It defines a shoulder that limits axial insertion of hose  304 . 
     Conical wall  315  extends between intermediate radially enlarged sleeve portion  314  and the internal bore  303  of tube  302 . It defines a shoulder that limits axial insertion of insert  306  into tube  302 . 
     The insert  306  is cylindrical and has an axial length that is somewhat longer than the axial distance between the shoulder defined by wall  315  and the free end of the tube  302 . It defines throughbore  316  which provides a fluid path between the internal bore of tube  303  and the internal bore  305  of the hose  304 . The cross sectional area of bore  316  is about seventy percent (70%) of the cross sectional area of bore  305  of hose  304  as in previous embodiments. 
     The insert  306  is made from metal, although the insert  306  could be made from the same material as the insert  106  of the embodiment of  FIGS. 1 and 2  or the insert  206  of the embodiment of  FIGS. 3 and 4 . A suitable material for the insert is steel or aluminum. 
     Insert  306  is a generally elongate cylindrical tube defining end portion  307  for insertion into tube  302  and end portion or barrel  308  for insertion into hose  304 . It defines throughbore  316  described above. It includes an outer cylindrical surface  326  over which is a layer  309  of polymeric material described below. This layer may be overmolded onto outer cylindrical surface  326  or otherwise bonded to outer cylindrical surface  326 . Alternatively, layer  309  may comprise a loose polymeric sleeve having an inner bore sized to receive the outer cylindrical surface  326  of insert  306 . Bonding of the polymeric sleeve to the insert and hose occurs on insertion into the hose and causing frictional heating. 
     The outer diameter over the outer polymeric layer  309  that is somewhat larger than the internal bore  305  of hose  304  and the intermediate radially enlarged sleeve portion  314 . The insert is received in bore  305  of hose  304  and intermediate radially enlarged sleeve portion  314  with minimal axial insertion force. 
     Hose  304  is flexible and includes internal bore  305  and includes an end portion that defines an insert receiving portion. It may be a mono-layer hose of extruded polyamide. 
     In accordance with the present invention, outer layer  309  of insert  306  is a thermoplastic or thermoplastic blend material suitable for vehicular air conditioning systems. It has a thickness of approximately 0.2 mm. The layer material is chosen for its resistance to compressor lubricating oils such as polyalkylene glycol (PAG) or polyol ester (POE), resistance to diffusion of refrigerants such as HFC134a or HFC152a, resistance to the refrigerants in terms of chemical extraction, and capable of performing in a temperature range of −30 to +150° C. 
     A suitable material for layer  309  is polyamide 6-6 or a blend of polyamide 6-6 and IIR (Butal) elastomer. This material also well suited for use in the present invention, since the thermoplastic material can be fused together to form a strong and leak-tight joint using friction. 
     The coupling  300  of  FIGS. 1 and 5  is assembled by axially inserting end portion or barrel  308  of insert  306  into the bore  305  of hose  304 . Since the outer cylindrical surface of barrel  308  over outer polymeric layer  309  has a diameter larger than the bore  305  of hose  304 , these surfaces are in contact with a small radially inward force imparted to the barrel  308  by hose  304 . 
     The insert is rotated about its axis or vibrated axially at a rate to generate heat during insertion. The friction from the spinning or vibratory contact causes surface melting of the outer layer  309  and inner bore of hose  304  which results in a fusing of the layer to the inner bore  305  of hose  304 . Alternatively, the bonding of the outer layer  309  to the inner bore  305  hose  304  may be accomplished by high frequency or ultra-sonic heating of the thermoplastic material of the sleeve. If, as contemplated in an embodiment described above, the sleeve  309  is not initially bonded to insert  306  the high frequency or ultra-sonic heating bonds the thermoplastic layer  309  to both the outer cylindrical surface  326  of insert  306  and the inner bore  305  of hose  304 . It is also contemplated that a solvent could be used, or an adhesive layer could be employed between the polymeric layer and the adjacent surface. 
     As inserted, insert  306  extends from free end of hose  304  about the same axial length as the axial spacing between radially annular wall  313  and conical wall  315 . The sub-assembly of the hose  304  and insert  306  is then connected to tube  302 . The exposed end portion  307  of insert  306  is inserted into the end of the tube  302  until the free end abuts the shoulder defined by conical wall  315 . This positions the end of hose  304  within radially enlarged sleeve portion  310  with free end of the hose abutting radially annular wall  313 . 
     The intermediate radially enlarged portion  314  of tube  302  is plastically deformed or crimped radially inward to collapse the portion  314  onto the cylindrical surface of the insert  306 . The crimp at  328  secures the insert  306  to the tube. This depression of the sleeve portion  314  compresses the polymeric layer  309  between the inner surface of the sleeve and the outer cylindrical surface  326  of the end portion  307  of insert  306 . This operation also causes a small radial inward plastic deformation or indentation  329  of sleeve  306 . 
     The outer polymeric layer  309  of insert  306  is thereby sealed against the inner cylindrical surface of intermediate radially enlarged portion  311  of tube  302  to create a fluid tight seal. 
     The radially enlarged sleeve portion  310  which overlies the end of hose  304  is crimped or plastically deformed radially inwardly onto the hose forming crimps or depressions  310 . The annular wall of the hose is compressed between the outer cylindrical surface  326  of insert  304  and the radially enlarged sleeve portion  310  to mechanically secure the hose to the insert. The crimping operation may be done in sequence or simultaneously. 
     The insert  306  is sealed relative to rigid tube  302  by the polymeric layer  309 . The insert  306  is sealed to the inner surface of hose  304  by the bond created by the surface melting of polymeric layer  309  to the internal bore of hose  304 . 
     In this design variation, the thermoplastic layer serves as the sealing means to provide a fluid tight seal to the rigid tube  302 . The radially inward plastic deformation of intermediate radially enlarged sleeve  314  at crimp  328  also causes a radially inward plastic deformation  329  of the cylindrical insert  306 . The resulting depression of the insert  306  forms a shoulder which serves to secure the insert  306  to the tube end portion  307  within intermediate radially enlarged sleeve  314 . 
     Various features of the present invention have been shown and described with reference to the illustrated embodiments. It should be understood that modifications may be made without departing from the scope of the invention.