Abstract:
Metal tubes, such as the small diameter metal tubes used in hydraulic braking systems, are connected to hoses also used in such systems by fittings which are configured to receive radially projecting beads on the metal tubes. Each of the fittings includes a body portion with a bore therethrough and a crimping collar which is unitary with the body portion. The body portion receives an insertion end of the tube therethrough, which insertion portion projects into the unitary crimping collar. A radially extending bead on the tube is received in a recess adjacent the bore through the body portion. In one embodiment, the tube is held in place by another bead which is seated in another recess at the opposite end of the bore.

Description:
This application is a national stage of PCT/US99/06365 filed Mar. 24, 1999 and claims benefit of Provisional Application No. 60/079,152 and 60/101,630 filed Mar. 24, 1998 and Sep. 24, 1998 respectively. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to high-pressure integral tube coupling arrangements. More particularly, the present invention relates to such arrangements for coupling flexible hoses, such as a reinforced rubber hoses to metal tubes for use in systems such as vehicle brake and clutch systems. 
     BACKGROUND OF THE INVENTION 
     In discussing the automotive industry, the Background of U.S. Pat. No. 5,037,142 states: “a wide variety of connector devices have been utilized to connect tubes to hoses for conducting fluid therethrough or transmitting a hydraulic force through a column of oil contained therein. In many cases, specialized couplings are required which not only hydraulically connect adjacent tubes or pipes, hoses and other conduits in a fluid-tight manner, but also provide effective support while allowing relative movement of components and providing protection in relatively harsh environments.” 
     Current methods for joining hoses to metal tubes still substantially rely on threaded couplings in which an externally threaded hollow nut is threaded into a internally threaded fitting to hold a flared tube tightly within the fitting. Since both the nut and the fitting must be machined, they are relatively expensive. In addition, making the connection is time consuming and labor intensive because it is not conveniently adaptable to automation. Moreover, quality control is difficult because there is the possibility of threaded components being joined without proper alignment so that threads are stripped, resulting in joints that leak and are subject to failure when operated at high pressures over long time periods of time in adverse environments. In view of these difficulties, there have been attempts to form couplings which do not require threaded components. Brazing a tube onto a hose fitting is one approach. Since these couplings are frequently exposed when used with brake systems, clutches and hoses, they are subject to environmental degradation because of moisture, road salt, wide temperature fluctuations and mechanical impacts and vibrations, all of which combine to accelerate corrosion. In order to protect brazed joints from corrosion, it is necessary to plate the assemblies which is in and of itself a relatively expensive undertaking. Moreover, these assemblies frequently require parts which have multiple elements each of which has the potential to provide a leak path and each of which must be handled and stored. 
     The technology of coupling hoses and tubes is now generally going to “quick-connect” type couplings in which all that is required to achieve a fluid tight connection is for two components being joined to be axially pushed toward one another, so that there is no need to rotate components of a coupling, one with respect to the other. When coupling metal tubes to rubber hoses, it is the practice to crimp the rubber hose within the coupling which is a rapid, reliable process requiring only a single metal-deforming step once the hose is inserted into the coupling. In order to further simplify assembly so as to reduce cost, it is desirable to simplify connecting the tube to a crimpable fitting. 
     SUMMARY OF THE INVENTION 
     In view of the aforementioned considerations, it is a feature of the present invention to provide new and improved tube-to-hose couplings which are reliable, inexpensive and yet require manufacturing steps which are minimal and do not introduce difficulties of their own. 
     In view of this feature and other features, the present invention is directed to a coupling arrangement for connecting a tube to a hose wherein the tube has a main portion and an insertion portion, the insertion portion being inserted through the fitting into the hose. The tube further has at least a first outwardly extending radial projection which cooperates with the fitting, the insertion portion of the tube extending beyond the radial projection to the terminus of the tube. The fitting has a first portion with a bore for receiving the tube therethrough and a second portion extending axially from the first portion for receiving the hose therein, with an interior surface on the first portion facing the second portion. The tube is disposed in the bore of the fitting with the outwardly extending projection abutting the interior surface on the first portion and the insertion portion extending into the second portion of the tube for insertion into the hose. 
     In a further aspect, the fitting includes a second abutment surface thereon facing away from the second portion for opposing axial movement of the tube toward the second portion of the fitting, and in a still further aspect, the portion of the tube engaged by the second abutment surface is on the first projection. 
     In a further aspect, the second abutment surface is on a portion of the fitting which is radially and axially deformed into abutment with the second abutment surface. 
     In still a further aspect, the second axially extending abutment is at a radially extending end of the fitting. 
     In a further aspect, the second portion of the fitting is a crimping collar for radially engaging the hose while the insertion portion of the tube is within the hose. 
     In still a further aspect of the invention, the main portion of the tube is covered with a layer of deformable protective material with the insertion portion and radially extending radial protection being uncoated. In accordance with this aspect of the invention, there is a metal-to-metal seal between the fitting and the uncoated radial projection. On the other hand, the definable protective material may be pressed into the fitting to provide a sealing area. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Various other features and attendant advantages of the present invention will be more fully appreciated as the same becomes better understood when considered in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the several views, and wherein: 
     FIG. 1 is a perspective view of a prior art arrangement for joining a metal tube to a flexible hose; 
     FIG. 2 is a side view, mostly in elevation, showing a first embodiment of a prior art threaded coupling used to join a tube to a hose; 
     FIG. 3 is a side view, mostly in elevation, showing a second embodiment of a prior art threaded coupling used to join a metal tube to a hose; 
     FIG. 4 is a side elevation of a prior art brazed joint used to couple a metal tube to a flexible hose; 
     FIG. 5 is a side view, mostly in elevation, showing a first embodiment of a coupling in accordance with the present invention utilized to couple metal tube to a flexible hose; 
     FIGS. 6A-6D are side views, mostly in elevation, illustrating the fabrication and assembly of the coupling of FIG. 5; 
     FIG. 7 is a side elevation showing the tube of the present invention, but for clarity illustrated without the fitting; 
     FIG. 8 is a side elevation of a fitting shown in FIGS. 5,  6 B and  6 D showing an embodiment of the fitting with pockets for receiving beads formed on the tube; 
     FIG. 9 is a side elevation of a second embodiment of the fitting of FIGS. 5,  6 B and  6 D having no pockets for receiving beads on the tube; 
     FIG. 10 is a side elevation showing a third embodiment of the invention; 
     FIG. 11 is a side elevation of a fourth embodiment of the invention; and 
     FIGS. 12A-D are side elevation views showing a preferred assembly technique for embodiment of the invention illustrated in FIG.  11 . 
    
    
     DETAILED DESCRIPTION 
     Prior Art Arrangements: FIGS.  1 - 4   
     Referring now to FIG. 1, there is shown a prior art coupling arrangements  19  for connecting relatively small diameter tubes  20  such as brake tubes to fittings  21  by threaded insert-type connections  22 . The fittings  21  are crimped to a hose  23  which carries relatively high pressure hydraulic fluid. In FIG. 1, a part of a truck chassis or frame  24  retains the coupling  19  thereon with a bracket  25  to hold the coupling rigid with respect to the frame. The hose  23  is relatively flexible and may be retained to other portions of the chassis by clamps while the tubes  20  may also be retained to the chassis  24  by clamps  25 . One of the tubes  20  is attached to a hydraulically driven device such as a brake caliper  28  in a disk brake  29 . The present invention replaces the couplings  19  with a more reliable and more economical coupling arrangements. While a disk brake  29  is shown in FIG. 1, the invention has other uses for other types of hydraulic connections such as connections for clutches, and any other arrangement in which a flexible hose is connected to a rigid tube. 
     Referring now to FIGS. 2 and 3 which show in more detail the prior art coupling  19  of FIG. 1, it is seen that the threaded nut  22  is received in a threaded recess  31  of the fitting  21  while the hose  23  is crimped to the fitting via a crimping collar  32 . In the arrangement of FIG. 2, the tube  20  has a flared end  33  and the fitting  21  has an inverted or convex seat  34 . In the embodiment of FIG. 3, the fitting  21 ′ has a concave seat  34 ′ which receives a bubble end  33 ′ of the tube  20 ′. The externally threaded nut  22 ′ then threads into the threaded bore  31  ′ in the same way that the threaded nut  22  threads into the threaded bore  31  of FIG.  2 . In practice, the arrangements of FIGS. 2 and 3 tend to have multiple components. 
     Referring now to FIG. 4, in an attempt to avoid the expense and minimize the difficulties of a coupling  19 , such as the coupling of FIGS. 2 and 3, wherein an externally threaded nut  22 ,  22 ′ must be threaded into a threaded bore  31 ,  31 ′, the tube  20 ″ of FIG. 4 is press-fitted into a smooth recess  31 ″ of a fitting  21 ″ and copper brazed at juncture  36 . The fitting  21 ″ is then plated, which requires plating of an assembly that has the relatively long portion of the tube  20 ″ attached to the fitting  21 ″. In practice, the arrangement of FIG. 4 also tends to use an insertion tube  37 , which results in more part-to-part junctures that increase the number of potential leak paths. 
     Embodiments of the Invention: FIGS.  5 - 12   
     In order to improve upon the couplings illustrated in FIGS. 1-4 as well as other couplings, the present invention eliminates a need to physically join the components of the tube-to-hose couplings by hand at assembly plants, as well as reducing leak paths, component costs and part number counts. Moreover, as opposed to brazed tube designs, such as that of FIG. 4, tolerance control is increased, as is routing control. 
     Referring now to the first embodiment of the present invention illustrated in FIGS. 5-9, a high pressure integral tube coupling  40  enables a direct connection between a metal tube  50  and a flexible hose  23  (see FIG.  1 ), such as a high pressure resistant rubber hose, without a need for rotating threaded coupling components or brazing, thus eliminating parts or steps while retaining their function. As is seen in FIG. 5, the metal tube  50  is positioned within a body portion  51  of a fitting  52  to which the hose  23  of FIG. 1 is subsequently coupled by deforming a crimping collar  53  therearound so that the hose is axially retained within the fitting  52  and is radially sealed against an end portion  54  of the tube. The tube  50  corresponds to the tubes  20  shown in the prior art arrangements of FIGS. 1-4 and has an internal diameter of about 0.1250 inch, which internal diameter could range from about 0.125 to about 0.145 inch. 
     In order to retain the tube  50  in the fitting  52 , a back bead  56  is preferably seated within an annular bead pocket  58  formed in a back end  59  of the fitting  52  while a front bead  60  is preferably seated in a pocket  62  formed in front end  63  of the fitting located just before the crimping collar  53 . A smooth bore  66  extends completely through the fitting  52  into a cylindrical space  68  defined by the crimping collar  53 . While the pockets  58  and  62  are preferable, it is within the scope of this disclosure to form the coupling without the pockets by crimping the tube  50  directly against the radial end surfaces of the fitting (See FIG.  9 ). 
     The diameter d 1 , of the smooth bore  66  is slightly greater than the diameter d 2  of the tube  50  so that the tube slides through the smooth bore. While the diameter d 1  is slightly larger than the diameter of d 2 , it need only be large enough so that the d 2  will slide readily therethrough. There could, however, be a slight press fit of the tube  50  within the bore  66 . 
     The end  54  of the tube  50  has a reduced diameter portion  67  of a diameter d 3  which is slidably receivable within the bore  70  of the hose  23  and is of a length substantially equal to that of the crimping collar  53 . Consequently, the bore  70  of the hose  23  is supported during the crimping step which deforms the material  72  of the hose. 
     Referring now to FIGS. 6A-6D which illustrate the method fabricating and assembling the coupling  40 , it is seen that the metal tube  50  has its end portion  54  drawn to have the reduced diameter d 3  which is less than the diameter d 2  of the tube  50 . As is seen in FIG. 6B, the back bead  56  is formed by an applied force which pushes a portion  76  of the tube  50  back, thus forming a beaded area in proximity with line  78 . 
     As is seen in FIG. 6C, the thus deformed tube  50  is inserted through the smooth bore  66  of the fitting  52  so that the back bead  56  fits into the annular bead pocket  58  at the back end  59  of the body  51  of the fitting. The annular bead pocket  58  is formed in or machined in the back end  59  of the fitting and has a diameter substantially greater than the diameter d 2  of the smooth bore  66 . It is to be kept in mind that the bead pocket  58  is a desirable but optional feature. Referring now to FIG. 6D in combination with FIG. 6C, the front bead  60  is then formed by using an applied force to the tube  50  rearwardly so that a portion  80  of the tube  50  deforms into the front bead  60  which seats within the annular front bead pocket  62  at the front end  64  of the body  51  of fitting  52 . The structure of the tube  50  in the absence of the fitting  52  is shown in FIG. 7, while the structure of the fitting absent the tube is shown in FIG.  8 . 
     In the first embodiment of the invention, it is seen that the coupling  40  is accomplished by two axial deformations of the tube  50 , one prior to inserting the tube  50  into the fitting  52  and the other subsequent to the insertion. The final step is to radially crimp the crimping collar  53  which is a conventional one-step procedure. If the arrangement is to be used with the brake line of FIG. 1, the fitting  52  with the tube  50  connected thereto may be first inserted into an opening in the bracket  25  and a sliding clip slid into the annular groove  87  in the fitting  52 . The hose  23  is then inserted in the space  68  in the crimping collar  53  and the crimping collar crimped about the hose. By having a press fitting between the tube  50  and the fitting  52 , rotation of the fitting relative to the tube is eliminated while maintaining a fluid tight seal. 
     Preferably, the metal tube  50  is made of steel and is pre-coated by SAE-J527 Standards, sliding fit. Other materials which may be used are copper, nickel, NYLON® (polyamide) or polyvinyl fluoride. If relatively thick plastic coatings such as NYLON® are used, the coating preferably terminates before the first bead  56 ; however, as is seen in the third embodiment of FIGS. 10 and 11, can continue to bead  60 . The barbed or stem structure beyond the beads  56  and  60  has a controlled inside diameter as well as a controlled outside diameter which permits the assembly to pass the Federal Motor Vehicle Safety Standards for minimum fluid passage diameter. Moreover, the barb or stem structure can be produced either with or without annular grooves to increase tensile integrity of the coupling. Since the end  54  of the tube is received directly within the bore  70  of the hose  23 , potential leak paths which occur with additional elements, such as those in prior art threaded connections and brazed tubular supports, are eliminated. 
     Referring now to FIG. 9, there is shown a second embodiment of the invention, wherein the bead pockets  58  and  62  are deleted from the fitting  52 ′ so that beads  56 ′ and  60 ′ press directly against the radially extending back and front end surfaces  80  and  82 , respectively of the fitting  52 ′. Friction between the end surface  80  and back bead  56  and between the front end surface  82  and the front bead  60  prevents rotation of the tube  50  within the fitting. In addition, there is a slight friction fit between the tube  50  and the bore  66 ′ which provides a fluid seal. 
     Referring now to FIG. 10, there is shown a third embodiment of the invention wherein a tube  90  is inserted into a fitting  92  having a crimping collar  93 . The tube  90  has a necked down portion  94  joined thereto by a frusto-conical section or tapered  95 . The frusto-conical section  95  joins an intermediate section  96  just in front of a bead  97 . The fitting  92  has a smooth bore  100  that has an abutment surface  101  defined by an annular shoulder  102  therein that is disposed within in an annular recess  104 . As with the embodiment of FIGS. 5-9, the tube  90  is shoved into the fitting  92  (as shown in FIG. 6C) until the bead  97  abuts the shoulder  102  of the abutment surface  101 . An annular portion  106  of the wall of the recess  104  is then deformed by staking the portion  106  against the bead  97  to retain the tube  90  within the bore  100  of the fitting  92 . Thereafter, a portion  110  of a second annular recess  112  within the fitting proximate the crimping collar  93  is deformed against the tapered section  95  of the tube  90  to provide a tapered portion  113  of the bore  100  against which the tapered portion of the tube seats. This seals the tube  90  within the fitting  92  at substantially three locations, whereafter the hose  23  is secured within the fitting  92  by deforming the crimping collar  93 . The arrangement of the second embodiment of the invention shown in FIG. 10 is used substantially as the arrangement of the first embodiment shown in FIGS. 5-9. As with the embodiments of FIGS. 5-8 and  9 , the embodiment of FIG. 10 is used in situations such as that of FIG. 1 where a flexible hose  23  connects a source of hydraulic fluid to a tube  20 , which tube retains fluid which operates a hydraulic device, such as the calipers of a brake, or a clutch, or any other device requiring high pressure hydraulic fluid delivered via a flexible hose. 
     Referring now to FIGS.  11  and  12 A-D, there is shown a fourth embodiment of the invention wherein a metal tube  200  is coupled to the hose  23  by a fitting  202  to form a coupling  203 . The metal tube  200  has a drawn down portion  204  which has a relatively small outside diameter d 1  which is less than the outside diameter d 2  of a main portion  205  of the tube. In addition, the tube  200  has an annular bead  206  having a first axially facing surface  208  and a second axially facing surface  210 . Tube  200  is received through a smooth bore  212  in a body portion  213  of the fitting  202  and, if the metal tube does not have a plastic coating, may have an interference fit. Tube  200  is retained within the fitting  202  by abutment between the first surface  208  of the bead  206  with a shoulder  216  adjacent the bore  212  and by a swagged, staked or otherwise deformed annular portion  218  of the fitting  202  that forms a second abutment which engages the surface  210  of the bead. A surface of the second abutment faces away from hollow portion  230 . The fitting  202  and tube  200  are therefore prevented from any axial or rotational movement, one with respect to the other while also being provided with metal-to-metal fluid seals  219  and  216  which prevent entry of moisture and corrosive agents that might degrade the interior of the coupling. 
     Preferably, the main portion  205  of the metal tube  200  is coated or covered with a layer  220  of a plastic material such as, for example, a polyamide, i.e., NYLON®, which layer of plastic material terminates before or at the bead  206  leaving the bead uncoated for the metal-to-metal seal  219  with the fitting as well as leaving the small diameter portion  204  uncoated for ready receipt in the bore of the hose  23 . Examples of other plastic materials which may be used are polyvinylfluoride or polypropylene. 
     A preferred example of a tube configuration for the tube  200  comprises a base tube of SAE 1008/1010 mild steel with a layer of copper plating over which is a 10-15 μm 95% zinc/5% aluminum hot dip coating. The layer of plastic material  220  is preferably a layer of polyamide over a binder layer which is on average about 3.5 μm thick. 
     Referring now to FIGS. 12A-12D, preferred steps in assembling the coupling  203  are shown in sequence. As is seen in FIG. 12A, tube  200  is provided. Tube  200  is drawn to provide the small diameter portion  204  and to form frusto-conical portion  222  which joins the small diameter portion  201  to the remainder of the tube  200 . As is seen in FIG. 12B, the tube is deformed by pressing axially against the tube so that it bulges outwardly to form the bubble  206  generally in the location of the fiusto-conical portion  222 . If the entire tube  200  has previously been coated with a plastic layer  220 , the plastic layer is stripped from the insertion portion  204  and the bead  206  prior to drawing. 
     There are a number of methods to remove a portion of the plastic layer  220  from a portion of the tube  200 . These methods include applying mechanical cutting tools, abrasive wheels or brushes or using laser ablation, chemical solvents or water jet ablation. The tube  200  may be axially moved and rotated as the plastic and other non-metallic materials are stripped therefrom preferably prior to drawing or otherwise deforming the tube  200 . 
     Referring now to FIG. 12C, the fitting  202  is slid along the length of the tube  200  from its opposite end or, in the alternative, the tube is simply inserted into the bore  212  until the surface  208  on the bead  206  is abutted by the shoulder  216  that is adjacent the end of the bore. Preferably, the fit between the tube  200  and the bore  212  is a sliding fit with the plastic layer  220  sliding within the bore. The fit between the tube  200  and bore may be sufficiently tight to form a fluid tight seal. As is seen in FIG. 12D, the annular portion  218  of the wide portion of the bore  212  is then swaged, staked or otherwise deformed against the second face  210  of the bead  206  in order to form the coupling  203  which firmly retains the tube  200  within the fitting  202  and forms the metal-to-metal, fluid tight seal  219  therewith. 
     After the coupling  203  is formed, the hose  23  (FIG. 11) is inserted into a hollow portion  230  of the fitting  202  which forms a crimping collar that is unitary with the body portion  213  of the fitting. The crimping collar  230  is then deformed radially inwardly to retain the hose  23  permanently and non-rotatably in communication with the tube  200 . 
     By utilizing the arrangement of the present invention, tubes are retained within fittings, such as fittings for joining the tubes to hoses, utilizing mechanical steps which involve neither rotating the tube with respect to the fitting, brazing the tube to the fitting or using a retaining unit. 
     From the foregoing description, one skilled in the art can easily ascertain the essential characteristics of this invention, and without departing from the spirit and scope thereof, can make various changes and modification of the invention to adapt it to various usages and conditions.