JP2009019770A - Dissimilar metal pipes connecting structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a connecting structure for two pipes made of different metals capable of ensuring the fluid sealed connection of two pipes, the connecting structure being simplified by the use of a bonding agent layer laid in the connection part. <P>SOLUTION: The connecting structure for two dissimilar pipes consisting of metals having different coefficients of thermal expansion, whereby the connection ends of the pipes are put in the fluid sealed connection. The connection ends 1 and 2 are fitted to each other telescopically in order to form an overlapping region 3, where the bonding agent layer 4 is formed between the two connection ends 1 and 2 in the overlapping region 3, and the connection ends 1 and 2 are fitted to each other telescopically and pre-stressed in the radial direction at 20°C approximately. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a dissimilar metal pipe connection structure for fluid-tightly connecting connection ends of two metal pipes made of different metals having different coefficients of thermal expansion.

  A fluid-tight connection of a metal tube, usually formed as a ring metal bellows type or coiled bellows type special metal tube, to a unit for supplying or discharging liquid or gas, if at least the fluid is under pressure Causes problems when it is allowed to flow under pulsating pressure and under severe temperature fluctuations. Since the unit is not usually made of high-grade special steel for cost reasons, it is not a problem to bond a metal tube to the unit or unit connection port by material fusion. Therefore, the theme addressed by the present invention is to create a fluid sealable connection end portion of two different metal pipes made of different metals having different coefficients of thermal expansion, in particular, special steel and aluminum.

  A typical application field of such a fluid-sealed dissimilar metal pipe connection structure is a compressor or other device of an automobile air conditioner in which a refrigerant is allowed to flow not only under a pulsating high pressure but also over a wide range of temperature fluctuations. A pipe connection to the part.

  In the above application field, International Publication No. 2007/007917 (Patent Document 1) connects a stainless metal bellows tube to a stainless steel nipple by material fusion, and inserts the stainless steel nipple into an expanded aluminum tube. A method of applying an epoxy resin layer as an adhesive layer between both joints in the overlapping region has been proposed. Since the epoxy resin elastically fills the annular gap, the sealing of the connecting portion is ensured. On the other hand, the force acting between both connecting ends, in particular, the tensile force, torsional force and shearing force, is reduced between the stainless steel nipple and the aluminum tube. Further, it is absorbed by the engagement with a sleeve additionally mounted on the outer periphery of the aluminum tube. The reinforcement part enclosed in the bellows tube provides a further seal of the transition between the bellows tube and the stainless steel nipple, but in this case a further fastening collar is required to ensure this seal. However, on the one hand, there are a large number of components that are indispensable for guaranteeing the mechanical strength of the connection structure and on the other hand ensuring fluid sealing under given temperature and pressure conditions. The connection structure according to is not necessarily optimal for all use cases.

International Publication No. 2007/007917

  Therefore, an object of the present invention is to further simplify the connection structure that ensures fluid-sealed connection between two pipes made of different metals by using an adhesive layer disposed between the connection portions.

  In the dissimilar metal pipe connection structure for fluid-tightly connecting the connection ends of two metal pipes each having a different coefficient of thermal expansion, in order to achieve the above object, in the present invention, both connection ends are In order to form an overlap region, they are telescopically inserted into each other, an adhesive layer is formed between both connection ends in the overlap region, and both the connection ends are prestressed in the radial direction at about 20 ° C. It is inserted so as to be nested.

  Therefore, according to the present invention, both connecting ends are telescoped together and pre-stressed in the radial direction at about 20 ° C. This can be realized, for example, by press fitting or by heat treatment before or during the mutual insertion.

  The present invention recognizes that at its starting point there is a contradiction in the adhesive bonding of two metal tubes, each material having a different coefficient of thermal expansion. On the one hand, the adhesive forming the adhesive layer is a high-tensile adhesive that mechanically very stabilizes the connection of both connection ends. However, since these adhesives lose almost elasticity after curing, if a gap is formed due to the difference in coefficient of thermal expansion between both connection ends, the adhesive joint can even become brittle or broken, At least the sealing effect of the adhesive is impaired. On the other hand, the gap in the overlapping region between the two connection ends, which changes due to the difference in the expansion coefficient of the two metals, for example as used in the prior art described at the beginning, is filled in any case. There are durable elastic adhesives that guarantee the sealing effect as well as the persistence of the adhesive splice. However, such durable elastic adhesives are too soft to guarantee a practical connection fixing of both connection ends that resist tensile and torsional loads. Therefore, the prior art described at the beginning uses a number of geometrically complementary engagement members to reduce tension, torsion and shear forces on the adhesive layer functioning as a seal. ing.

Such a contradiction is that in the present invention, the connecting ends are telescoped together and pre-stressed radially at about 20 ° C., and in a preferred field of application, the pre-stress is preferably at least about −10 ° C. To about 110 ° C., in particular at least about −40 ° C. to at least about 180 ° C., so that no gaps or annular voids can occur in the overlapping regions of both connection ends within these temperature ranges. It is solved by doing so. Therefore, in a preferred embodiment, it is possible to use as the adhesive a high-tension adhesive that provides a tensile and shear strength of, for example, 20 N / mm ² and higher in the case of special steel. Such a high-tensile bond with such an adhesive is sufficient to ensure that both connecting ends are securely connected to each other under the loads that occur in the field of use. At the same time, the fact that the high-tensile adhesive has little elasticity in the cured state is not a disadvantage because such elasticity is not required. In addition, even when the temperature of the fluid flowing through fluctuates, there is no gap in the overlapping region between the connecting end portions, so that the adhesive changes the volume to maintain the adhesive joint mechanically and the surface sealing. There is no need to guarantee the stopping.

  Other features, operations, and effects of the present invention can be further improved by various different embodiments described below.

  If the combination of at least one of the two connection end portions and the pair of materials is aluminum and special steel, the connection end portion preferably made of special steel is inclined toward the end surface (its thickness decreases). If the thickness of the tapered member is increased so as to have a tapered surface, the thickness of the tapered member starts from the end surface and gradually increases, so that the tapered surface of the member ends. The concentrated load applied during the bending motion in the terminal end region is limited.

  At least one of the two connection end portions may have a projection portion that engages with the overlapping region and the surface of the other connection end portion by, for example, pushing away the material of the surface to realize engagement. This results in an intermeshing connection between the elements that can act as an anti-detachment and torsion prevention and correspondingly reduce the mechanical load on adhesive bonding. In this case, the protruding portion is formed so as to be higher as it is separated from the end face of the connection end portion, whereby the tensile force transmitted to the other connection end portion by the protrusion portion is the length of the overlapping region. This is preferable because it is distributed as evenly as possible throughout.

  In the case where both connecting end portions are provided with protrusions on the surface facing the overlapping region, these protrusions may be preferably formed as threads. In this way, both screw threads are screwed together, which results in a screw joint between the two connecting ends, which of course has an adhesive intervening according to the present invention. In addition to the twist prevention function, it forms a sealing function. The screw connection further makes it possible to insert an auxiliary elastic ring seal in an easy way between both connection ends.

Inserting an auxiliary elastic ring seal between the two connection ends adjacent to the overlap region or the overlap region zone may be carried out within the scope of the present invention irrespective of screw joints. Good.

  Needless to say, when at least one of the connection end portions is knurled in the overlapping region, the adhesive effect of the member by the adhesive is improved.

  Alternatively or additionally to the protrusions, at least partly in the overlap region, in order to create an interlocking fit with a tenon-like geometry that resists torsion of the two connection ends. It is also possible for the section to have a cross-section different from the cylindrical shape at both connection ends. This may be a polygonal cross section, but may also be an oval or other flat cross section.

  A special advantage is obtained by one embodiment of the invention in which one of the two connection ends is provided with an annular groove on its end face and the other connection end is inserted in the same place. In this case, the depth of insertion will create an overlapping region according to the present invention, and the adhesive is applied to at least one side between the annular groove wall and the inserted tube. In this case, the prestress according to the invention between the two interleaved connection ends does not have to act on the same groove wall of the annular groove over the entire temperature range, for example radially inward in the first temperature range And may act radially outward in the second temperature range. In this case, of course, there is no radial prestress in a uniquely oriented direction at temperatures between these two temperature ranges, but this is nevertheless an aspect within the scope of the present invention.

  As mentioned at the outset, the preferred field of application of the invention is to connect a metal corrugated tube to a unit or an aluminum tube piece manufactured, for example, as an extruded profile. In this case, it is advantageous if one of the connection end portions is part of a connection tube joined to the metal corrugated tube or metal bellows tube by material fusion. This connecting pipe is also made of special steel because corrugated pipes or metal bellows pipes are usually made of austenitic special steel, but may also be phylite special steel, preferably tube material or It may have a thicker wall thickness than the bellows tube material.

  Hereinafter, a plurality of embodiments of dissimilar metal pipe connection structures according to the present invention for connecting connection ends of two pipes will be described in detail with reference to the accompanying drawings.

  FIG. 1 shows a schematic partial sectional view of a connection structure formed according to the invention comprising a first connection end made of special steel and a second connection end made of aluminum. The first connection end 1 is a connection pipe welded to a ring-shaped bellows-type metal tube (not shown), while the second connection end 2 is a compressor connection port. The first connection end portion 1 is fitted into the second connection end portion 2, and an overlapping region 3 formed thereby has a high-tensile adhesive as an adhesive 4 between the connection end portions 1 and 2. It is applied over the entire surface. The connection end portions 1 and 2 of this embodiment are formed in a cylindrical shape. These connection end portions are prestressed with each other according to the present invention, and both the connection end portions 1 due to the difference in thermal expansion coefficient between aluminum and special steel even when the temperature range is from −40 ° C. to 180 ° C. 2 are pre-stressed so that no gap is formed in the overlapping region 3 between the two. The adhesive strength of the adhesive 4 is optimized by increasing the roughness of the outer surface of the first connection end 1 and the inner surface of the second connection end 2 in the overlapping region 3. Furthermore, the bonding strength is the outside of the overlap area 3 of the first connection end 1 made of special steel and biting into the connection end 2 of the second aluminum to form a meshing engagement against tensile and torsional forces. This is enhanced by the provision of the projecting portion 5 facing the surface. Since the thickness of the first connecting end 1 in the fitting zone 6 is gradually reduced inward toward the end surface 7, the bending rigidity of the special steel pipe is reduced at this point, and therefore the first thickness at the end surface 7 is reduced. The concentrated load applied to the aluminum tube at the end portion of the connection end 1 is reduced.

  The schematic partial cross-sectional view of FIG. 2 shows a first connection end 1 made of special steel, a second connection end 2 made of aluminum, and connection ends 1 and 2 fitted in a nested manner. The simplest form of a connection structure according to the invention is shown, which includes an adhesive 4 which is applied in a planar manner to the overlap region 3 to form a cylindrical adhesive sealing surface.

  FIG. 3 shows a diagram corresponding to FIGS. 1 and 2 of a further embodiment, in which the first connection end 1 made of special steel is an overlapping region between the connection ends 1 and 2. 3 has a projection 5 which is formed in a ring shape and bites into the second connection end 2 made of aluminum to form a tensile load receiver. The adhesive 4 also forms a cylindrical adhesive sealing surface, and in this embodiment, the tensile load is reduced by the tensile load receiver formed by the ring-shaped protrusion 5 as compared to the previous embodiment. Is done.

  FIG. 4 shows a further embodiment of the system according to the invention, in which the first connection end 1 made of special steel and the second connection end 2 made of aluminum are both in the overlapping region 3. Since the screws 8 are respectively provided, the connection structures 1 and 2 are not only fitted into each other but also screwed together. Nevertheless, the overlapping region 3, i.e. the screwing region, is coated with the adhesive 4 according to the invention in order to prevent loosening of the screw connection and to realize a planar seal. Furthermore, in this embodiment, an elastic ring seal 9 is provided at the end of the overlapping region 3 in order to ensure the sealing of the joint in any case.

  The system shown in FIG. 5 is basically the same as the system shown in FIG. 2 except that, in this case, the overlapping region 3 of the first connecting end (special steel) is formed as a knurled part 10. . This increases the adhesive force of the adhesive 4 and thereby improves the adhesive effect.

  FIG. 6 shows a view different from the other drawings, that is, a perspective view of the first connection end 1 that is fitted and integrally coupled to the second connection end (not shown). The end face 7 of the first connection end 1 is formed as a polygonal cross-section, in this case a hexagonal cross-section, so that the torsion of the connection structure according to the invention based on a mating fit against a torsional load Prevention is achieved.

  Finally, FIG. 7 shows the last embodiment of the present invention. In this case, a circumferential groove 11 is provided on the end face of the first connection end 1 made of special steel, and the second connection end 2 made of aluminum is inserted in the same place. Adhesive that adheres both connecting end portions 1 and 2 to each other in both the radially outer side and the radially inner side in the overlapping region 3 of both connecting end portions 1 and 2 and seals the overlapping region 3 in a planar manner 4 is applied. Since the circumferential groove is an annular groove, the second connection end 2 is surrounded by the first connection end 1 both inside and outside in the radial direction. Even so, a gap is formed between the first connection end 1 and the second connection end 2 so that the adhesive layer 4 cannot cope with both the radially inner side and the radially outer side of the overlapping region 3. There is no. On the contrary, due to the difference in the coefficient of thermal expansion, radial prestress according to the invention occurs between the two connection ends 1, 2 in the illustrated system.

  In addition, although the code | symbol is written in order to make contrast with drawing convenient for the term of a claim, this invention is not limited to the structure of an accompanying drawing by this entry.

Partial sectional view of a system formed according to the present invention. Same as FIG. 1, except for a partial sectional view of the embodiment Same as FIG. 1, except for a partial sectional view of the embodiment Same as FIG. 1, except for a partial sectional view of the embodiment Same as FIG. 1, except for a partial sectional view of the embodiment Partial perspective view of the connecting end used in the system according to the invention Same as FIG. 1, except for a partial sectional view of the embodiment

Explanation of symbols

1, 2: Connection end portion 3: Overlapping region 4: Adhesive layer

Claims (12)

In the dissimilar metal pipe connection structure for fluid-tightly connecting the connection ends of two metal pipes made of different metals having different coefficients of thermal expansion
Both connection ends (1, 2) are nested in each other to form an overlap region (3), and an adhesive layer (4) is provided between the connection ends (1, 2) in the overlap region (3). ) Is formed,
The dissimilar metal pipe connection structure is characterized in that the connection end portions (1, 2) are inserted in a nested manner so as to be prestressed in the radial direction at about 20 ° C.   The connection ends (1, 2) are pre-stressed in a radial direction relative to each other such that pre-stress is present over a temperature range of at least about -10 ° C to about 110 ° C. The dissimilar metal pipe connection structure described in 1.   The dissimilar metal pipe connection structure according to claim 1 or 2, wherein the adhesive layer (4) is made of a high-tensile adhesive.   4. At least one of the connection ends (1, 2) has a cross section whose thickness decreases towards its end surface (7). Different metal pipe connection structure.   5. At least one of said connecting ends (1) has a protrusion (5) that bites into the surface of the other connecting end (2) in said overlapping region (3). The dissimilar metal pipe connection structure as described in any one of Claims.   6. The dissimilar metal pipe connection according to claim 5, wherein the protrusion (5) is formed to have an inclined surface that becomes higher as the protrusion (5) is separated from the end face (7) of the connection end (1). Construction.   The screw (8) is formed at a location of the overlapping region (3) of the connection end (1, 2) and is screwed to each other. Dissimilar metal pipe connection structure.   The dissimilar metal pipe connection structure according to any one of claims 1 to 7, wherein at least one of the connection end portions (1) is knurled in the overlapping region (3).   The dissimilar metal pipe connection structure according to any one of claims 1 to 8, wherein the overlapping region (3) of the connection end (1, 2) has a cross section different from a cylindrical shape.   One of the connection end portions (1) is provided with an annular groove (11) on an end surface, and the other connection end portion (2) is inserted into the annular groove. The dissimilar metal pipe connection structure according to the item.   An auxiliary elastic ring seal (9) is inserted between the connecting ends (1, 2) in or adjacent to the overlapping region (3). The dissimilar metal pipe connection structure according to any one of 1 to 10.   12. At least one of the connection ends (1) is a part of a connection pipe joined to a metal corrugated pipe or a metal bellows pipe by material fusion. The dissimilar metal pipe connection structure described in 1.

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