JP2017141916A - Connection nut and piping set - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a connection nut capable of suppressing bimetallic corrosion without deteriorating workability, and a piping set.SOLUTION: A connection nut 320 is configured to connect a pipe member 310 to joint members 110A, 110B for an outdoor machine having an opening part, and joint members 210A, 210B for an indoor machine. The connection nut 320 is configured such that in a state where the pipe member 310 is connected to the joint members 110A, 110B, 210A, 210B, within a wall surface of the connection nut 320, a wall surface contacting with at least the pipe member 310 is covered with a galvanic corrosion suppression film 400.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a connection nut used for connecting pipe members and a piping set.

  Conventionally, as a refrigerant pipe for connecting an outdoor unit and an indoor unit in an air conditioner, a technique using an aluminum alloy aluminum pipe that can be stably supplied at a lower price than a copper pipe is known (for example, a patent) Reference 1).

  In the case of using an aluminum pipe as the refrigerant pipe, in the above-mentioned conventional patent document 1, the flare nut for connecting the aluminum pipe to the joint member fixed to the outdoor unit side and the indoor unit side is made of brass. In order to suppress the occurrence of dissimilar metal contact corrosion due to the fact that the flare nut is shaped, a cylindrical part is added to the normal nut body, and the gap between the cylindrical part and the aluminum tube is waterproofed with rubber It is set as the structure coat | covered with a cap.

JP 2010-48373 A

  However, when the conventional rubber waterproof cap is configured to cover the gap between the cylindrical portion and the aluminum tube, the work of inserting the aluminum tube into the flare nut covered with the rubber waterproof cap is made of rubber. When a force against the frictional resistance against the waterproof cap is required, workability is reduced, and when the rubber waterproof cap is deteriorated, there is a problem that moisture enters and a different metal contact corrosion occurs and the refrigerant leaks.

  An object of this invention is to provide the connection nut which can suppress dissimilar-metal contact corrosion, and a piping set, without reducing workability | operativity in view of the said conventional subject.

The first aspect of the present invention is
A connection nut for connecting a pipe member to a joint member having an opening,
In the connection nut, in a state in which the pipe member is connected to the joint member, at least a wall surface in contact with the pipe member is covered with a predetermined film among the wall surfaces of the connection nut. It is a connection nut.

The second aspect of the present invention
The connection nut has an outer peripheral surface having a polygonal cross section, and has a cylindrical body that is open at both ends.
The connection nut is
An internal thread portion that is formed from one end portion inside the cylindrical body to the near end of the other end portion and is screwed with an external thread portion on the outer peripheral surface of the joint member;
A penetrating portion formed in the other end portion through which the tube member penetrates;
In order to press and connect the funnel-shaped inclined surface at the end of the tube member, which is formed between the inner peripheral wall surface of the penetrating portion and the female screw portion, to the outer peripheral edge of the opening of the joint member A pressing portion, and
The first invention according to the first aspect, wherein the predetermined film is formed at least on an inner peripheral wall surface of the penetrating portion, the pressing portion, and an outer end surface on the other end side of the connection nut. Connection nut.

The third aspect of the present invention
The connection nut of the first or second aspect of the present invention;
The connection nut is provided with the pipe member provided so as to be arranged at both ends,
In the pipe set, the pipe member has a first metal as a main component, and the connection nut has a second metal different from the first metal as a main component. is there.

The fourth aspect of the present invention is
The pipe set according to the third aspect of the present invention, wherein the first metal is aluminum and the second metal is copper.

The fifth aspect of the present invention provides
The material of the pipe member is an aluminum alloy,
The material of the connection nut is brass,
The fourth book described above, wherein the predetermined film is a film having an electrical insulating property or a film containing a powder of a metal material and a resin material having a higher ionization tendency than the aluminum alloy. It is a piping set of an invention.

The sixth aspect of the present invention provides
The pipe member is a pipe member for connecting an outdoor unit and an indoor unit of an air conditioner through the joint member and the connection nut to circulate a refrigerant. It is any one piping set of the present invention.

  ADVANTAGE OF THE INVENTION According to this invention, the connection nut which can suppress dissimilar metal contact corrosion, and a piping set can be provided, without reducing workability | operativity.

The schematic diagram which showed typically the installation state of the air conditioner of this Embodiment FIG. 1 is an exploded schematic view schematically showing a connection between a joint member of the outdoor unit of the air conditioner 1 shown in FIG. 1, a joint member of the indoor unit, and a refrigerant pipe composed of a thick pipe member and a thin pipe member. (A): Enlarged sectional view of the connection nut and the pipe member shown in FIG. 2, (b): Enlarged sectional view of the joint member of the outdoor unit shown in FIG. 2, and the connection nut and the pipe member connected thereto. It is sectional drawing of the connection nut of this Embodiment, and is a figure which shows the range in which the electrolytic corrosion suppression film | membrane is formed The flowchart figure which shows the film | membrane formation process which forms an electrolytic corrosion suppression film | membrane in the connection nut of this Embodiment (A): Partial sectional view showing a state in which a connection nut is set in a jig used in the film forming step for forming an electrolytic corrosion suppression film of the present embodiment, (b): a plurality of connections set in the jig Schematic showing the state where the nut is immersed in a predetermined solution

  Hereinafter, an embodiment of a connection nut of the present invention and a piping set using the connection nut will be described with reference to the drawings.

  In the present embodiment, as an example, a case where a connection nut and a pipe set using the connection nut are used in a domestic air conditioner capable of cooling and heating will be described with a focus on the configuration.

  Drawing 1 is a mimetic diagram showing typically the installation state of air harmony machine 1 of this embodiment.

  Further, FIG. 2 shows the refrigerant composed of the joint members 110A and 110B of the outdoor unit 100 of the air conditioner 1 shown in FIG. 1, the joint members 210A and 210B of the indoor unit 200, the thick tube member 300A, and the thin tube member 300B. It is the decomposition | disassembly schematic diagram which decomposed | disassembled and showed typically the connection with the piping 300. FIG.

  3 (a) is an enlarged cross-sectional view of the connection nut 320 and the pipe member 310 shown in FIG. 2, and FIG. 3 (b) shows the joint member 110A of the outdoor unit 100 shown in FIG. It is an expanded sectional view of the connected connection nut 320 and the pipe member 310. 3A and 3B, the joint member 110A and the connection nut 320 are represented by solid lines, and the tube member 310 is represented by a two-dot chain line in order to make it easy to see the connection state of each part.

  As shown in FIG. 1, the air conditioner 1 according to the present embodiment includes an outdoor unit 100 installed outside the house 2, an indoor unit 200 installed inside the house 2, the outdoor unit 100, and the indoor unit 200. And a refrigerant pipe 300 constituted by a thick pipe member 300A and a thin pipe member 300B that constitute a refrigerant circulation path.

  Note that the refrigerant circulation direction in the large tube member 300A and the thin tube member 300B is reversed between the cooling operation and the heating operation.

  Further, in the air conditioner 1 of the present embodiment, the thin tube member 300B has basically the same configuration as the thick tube member 300A except for dimensions related to the tube diameter. explain. Moreover, in the figure (refer FIG. 2), about the thin tube member 300B, the same code | symbol was attached | subjected to the same structure as 300 A of thick tube members, and the description was abbreviate | omitted.

  As shown in FIG. 2, the thick tube member 300 </ b> A of the present embodiment is inserted and arranged on both ends of the tube member 310 having a flare portion 311 that is flared at both ends and expanded in a funnel shape. A pair of connection nuts 320 and 320, and a cylindrical heat insulating tube 330 that is disposed between the pair of connection nuts 320 and 320 and covers the pipe member 310.

  The thin tube member 300B has the same configuration as the thick tube member 300A as described above.

  Further, as shown in FIG. 2, the flare portion 311 on one side of the pipe member 310 is connected to the joint members 110 </ b> A and 110 </ b> B of the outdoor unit 100 by connection nuts 320 screwed to the joint members 110 </ b> A and 110 </ b> B of the outdoor unit 100. The flare portion 311 on the other side is connected to the joint members 210A and 210B of the indoor unit 200 by connection nuts 320 that are screwed into the joint members 210A and 210B of the indoor unit 200.

  In the air conditioner 1 of the present embodiment, the joint member 110B connected to the thin tube member 300B of the outdoor unit 100 is basically a thick tube member except for the size of the portion corresponding to the tube diameter of the tube member 310. This is the same configuration as the joint member 110A connected to 300A. Moreover, in the air conditioner 1 of this Embodiment, the connection structure of the one side flare part 311 and the joint members 110A and 110B of the outdoor unit 100 by the connection nut 320, and the other side flare part 311 and the indoor unit 200 are connected. The connection structure with the joint members 210A and 210B is the same structure.

  Therefore, below, it demonstrates centering on the connection structure of the flare part 311 of one side and the joint member 110A of the outdoor unit 100 by the connection nut 320. FIG.

  As shown in FIG. 3A, the connection nut 320 is a cylindrical body whose outer shape of the AA cross section perpendicular to the central axis 321 is hexagonal, and whose both ends are open. Further, as shown in FIGS. 3A to 3B, the connection nut 320 is formed of (1) the joint member 110A formed from one end portion inside the cylindrical body to the front of the other end portion. A female screw part 322 screwed into the male screw part 111 on the outer peripheral surface; (2) a through part 323 formed in the other end part through which the pipe member 310 passes; and (3) an inner peripheral wall surface 323a of the through part 323. The flare back surface 311a having a funnel-shaped inclined surface at the end of the tube member 310 formed between the inner thread portion 322 and the female screw portion 322 is pressed against the outer peripheral edge portion 112 having the inclined surface of the opening of the joint member 110A. And (4) a BB cross section (see FIG. 3A) perpendicular to the central axis 321 formed between the female screw portion 322 and the pressing portion 324 has a circular inner periphery. A groove portion 325.

  In the above configuration, in a state where the joint member 110A, the pipe member 310, and the connection nut 320 are arranged as shown in FIG. 3B, the connection nut 320 is tightened with a predetermined torque, thereby the pipe member 310. The flare back surface 311a is pressed by the pressing portion 324 of the connection nut 320 to the outer peripheral edge portion 112 having the inclined surface of the opening portion of the joint member 110A, and as a result, the flare inner surface 311b of the pipe member 310 is open to the opening portion of the joint member 110A. It is the structure which adhere | attaches reliably with the outer-periphery edge part 112 which has this inclined surface.

  In the present embodiment, the pipe member 310 is pure aluminum having an aluminum purity of 99.00% or higher (also simply referred to as aluminum in this specification), or an aluminum alloy in which various metal elements are added to pure aluminum. As an example, an aluminum alloy (Al-Mn type) of JIS standard indication A3003 may be mentioned, but the invention is not limited thereto.

  On the other hand, in the present embodiment, the connection nut 320, the outdoor unit side joint members 110A and 110B, and the indoor unit side joint members 210A and 210B are brass (that is, brass), and the pipe member 310 is a main component. Is different.

  In general, since an aluminum alloy has a higher ionization tendency than brass, the pipe member 310 is brought into contact with the connection nut 320 or the joint members 110A and 110B (210A and 210B), and moisture is interposed therebetween. Then, in the aluminum alloy pipe member 310, dissimilar metal contact corrosion (this is also simply referred to as “electric corrosion”) occurs, which causes refrigerant leakage.

  Therefore, in this embodiment, in order to suppress the electrolytic corrosion of the pipe member 310, the electrolytic corrosion suppression film 400 is formed in a predetermined range with respect to the connection nut 320 as shown in FIG.

  FIG. 4 is a cross-sectional view of the connection nut 320 of the present embodiment, and shows a range where the electrolytic corrosion suppression film 400 is formed.

  As shown in FIG. 4, the electrolytic corrosion suppression film 400 uses the outer end surface 326 on the penetrating portion 323 side of the connection nut 320 as a reference surface, and extends from the reference surface along the central axis 321, that is, the end portion of the pressing portion 324. The entire surface of the inner wall and the outer wall of the connection nut 320 included in the range of the distance H up to the boundary part 324BL between the pressing part 324 and the groove part 325 is covered.

  That is, as shown in FIG. 4, the electrolytic corrosion suppression film 400 includes a surface of the pressing portion 324 of the connection nut 320, an inner peripheral wall surface 323 a of the penetrating portion 323 connected to the surface of the pressing portion 324, and an inner peripheral wall surface 323 a thereof. The outer end surface 326 connected to the outer end surface 326 and the outer peripheral inclined surface 327 connected to the outer end surface 326 are covered with no gap, and the hexagonal outer peripheral surface 329 connected to the outer peripheral inclined surface 327 is within a certain range 328 (center in side view). The distance h along the axis 321). Here, the fixed range 328 is a very small range compared to the entire hexagonal outer peripheral surface 329.

  Here, the electrolytic corrosion suppression film 400 has a two-layer structure in which a first layer is a polyimide resin film, and a fluorine resin-containing polyimide resin film is formed thereon as a second layer. 15 μm to 30 μm. In addition, the electrolytic corrosion suppression film 400 has electrical insulation.

  In addition, the formation method of this electrolytic corrosion suppression film | membrane 400 is mentioned later.

  In the present embodiment, the first layer of the polyimide resin film alone does not provide good adhesion of the coating film to the corners of the connection nut 320, so two layers of fluororesin-containing polyimide resin having excellent paintability to the corners are provided. Although used for the eyes, the electrolytic corrosion suppression film 400 is not limited to the two-layer structure as long as the paintability at the corners can be secured, and may have a single-layer structure.

  Next, the reason why the electrolytic corrosion caused by the dissimilar metal contact between the pipe member 310 and the connection nut 320 or the joint member 110A in this embodiment is suppressed will be described.

  That is, according to the above configuration, in the state where the coupling member 110A, the pipe member 310, and the connection nut 320 formed with the electrolytic corrosion suppression film 400 (see FIG. 4) are arranged as shown in FIG. When the connection nut 320 on which the electrolytic corrosion suppression film 400 is formed is tightened with a predetermined torque, the flare back surface 311a of the pipe member 310 is joined to the joint member by the pressing portion 324 covered with the electrolytic corrosion suppression film 400. The outer peripheral edge 112 having the inclined surface of the opening 110A is reliably pressed. As a result, the flare inner surface 311b of the tube member 310 is in close contact with the outer peripheral edge portion 112 having the inclined surface of the opening of the joint member 110A, and the refrigerant inside the tube member 310 causes the space portion 325a around the groove portion 325. (Refer to FIG. 3B) There is no leakage.

  From the above, moisture does not enter the space portion 325a from the gap 323b (see FIG. 3B) generated between the penetrating portion 323 and the pipe member 310. Further, moisture does not pass through a portion where the male screw portion 111 of the joint member 110A and the female screw portion 322 of the connection nut 320 are engaged with each other, and does not enter the space portion 325a.

  Therefore, since moisture or the like that promotes electrolytic corrosion does not enter the space 325a in the first place, the joint portion in which the tip portion 311c of the tube member 310 that has been subjected to flare processing and the electrolytic corrosion suppression film 400 are not formed. Electrolytic corrosion does not occur between the outer peripheral edge 112 having the inclined surface of the opening of the member 110A.

  On the other hand, moisture can enter the gap 323b (see FIG. 3B) generated between the through-portion 323 and the tube member 310, but at least the surface of the pressing portion 324 of the connection nut 320 and the pressing portion 324. As described above, the inner peripheral wall surface 323a of the penetrating portion 323 connected to the surface and the outer end surface 326 connected to the inner peripheral wall surface 323a of the penetrating portion 323 are made of resin having electrical insulation and excellent adhesion. It is covered with the electrolytic corrosion suppression film 400 (see FIG. 4).

  Therefore, if the electrolytic corrosion suppression film 400 does not deteriorate or peel off over time, the outer peripheral surface of the aluminum alloy tube member 310 and the metal surface of the brass connection nut 320 are in electrical contact. Therefore, no electric corrosion occurs.

  From the above, in the refrigerant pipe 300 including the thick pipe member 300A and the thin pipe member 300B, there is no need to put a rubber waterproof cap as in the conventional case. , And between the pipe member 310 and the joint members 110 </ b> A and 110 </ b> B (210 </ b> A and 210 </ b> B), it is possible to suppress the occurrence of electrolytic corrosion due to the dissimilar metal contact to the pipe member 310.

  Further, as shown in FIG. 4, since the electrolytic corrosion suppression film 400 is not covered with the female thread portion 322 of the connection nut 320, the tightening torque when the connection nut 320 is tightened to the joint members 110A and 110B (210A and 210B). Does not adversely affect

  That is, assuming that the electrolytic corrosion suppressing film 400 is coated on the female thread portion 322 of the connection nut 320, if the electrolytic corrosion suppressing film 400 is too thicker than a predetermined thickness, it can be completely tightened even with a specified tightening torque. If the film is not tightened and the film thickness is too thin, there is a problem that the screw part slips and tightens too much when tightened with a specified tightening torque. Therefore, in order to avoid this problem, it is important to control the film thickness in the manufacturing process so that the film thickness of the electrolytic corrosion suppression film 400 falls within an allowable range.

  Further, as shown in FIG. 4, the electrolytic corrosion suppression film 400 is not covered on the hexagonal outer peripheral surface 329 of the connection nut 320 except for a certain range 328. Therefore, if it is assumed that the hexagonal outer peripheral surface 329 of the connection nut 320 is also covered with the electrolytic corrosion suppression film 400, when the connection nut 320 is tightened to the joint members 110A and 110B (210A and 210B), the hexagon Although the wrench may slide on the film covered with the hexagonal outer peripheral surface 329 of the connection nut 320 and become difficult to tighten, such a problem does not occur in the present embodiment.

  The configuration including the thick tube member 300A, the thin tube member 300B, or both the large tube member 300A and the thin tube member 300B according to the present embodiment corresponds to an example of the piping set of the present invention. Further, the electrolytic corrosion suppression film 400 of the present embodiment corresponds to an example of a predetermined film of the present invention.

  Next, a method for forming the electrolytic corrosion suppression film 400 will be described with reference to FIGS.

  FIG. 5 is a flowchart showing a film forming process for forming the electrolytic corrosion suppression film 400 on the connection nut 320 of the present embodiment.

  FIG. 6A is a partial cross-sectional view showing a state in which the connection nut 320 is set on the jig 500. FIG. 6B shows a plurality of connection nuts 320 set on the jig 500 in a predetermined state. It is the schematic which shows the state immersed in the solution.

  As shown in FIG. 5, a plurality of uncoated connection nuts 320 are prepared and immersed in a cleaning solution for cleaning (see step S101).

  Next, a plurality of uncoated connection nuts 320 that have been cleaned are set on the jig 500 (see step S102).

  In the jig 500, m × n uncoated connection nuts 320 are arranged in a lattice shape in the vertical direction, m pieces and in the horizontal direction, n pieces, in a bottom view.

  Here, the configuration of the jig 500 will be described with reference to FIGS. 6 (a) to 6 (b).

  As shown in FIG. 6B, the jig 500 has a grid-like (vertical direction) view of the connection nut fixing protrusion 502 having a male thread 503 formed at the tip on the lower surface of the jig body 501. m, n in the horizontal direction). Further, the male screw portion 503 is set to have the same dimensions as the male screw portion 111 (see FIG. 3B) of the joint member 110A (110B) except for the front end portion 503a. Fully screwable. Further, the front end portion 503a of the male screw portion 503 is flat except for the air vent hole 504, and the groove portion 325 (see FIG. 6A) in a state where the connection nut 320 is fastened to the connection nut fixing projection 502. It is configured not to protrude into the range. The air vent hole 504 extends from the tip 503a of the connection nut fixing projection 502 to the root, bends toward the outer peripheral surface of the root, and is open to the atmosphere.

  Further, the jig 500 is fixed to a jig lifting device (not shown) so as to be able to be raised and lowered, and the jig lifting device is configured such that the lowering distance from the initial position of the jig 500 can be adjusted.

  Accordingly, as shown in FIG. 6B, a connection nut 320 is attached to a predetermined solution 610 (in this embodiment, a polyimide solution or a polyimide solution containing a fluororesin) placed in the immersion container 600 as shown in FIG. It can be immersed from the end face 326 to a distance H.

  Thereby, the coating range of the electrolytic corrosion suppression film 400 can be always ensured stably.

  The tip 503a of the male screw portion 503 is configured not to protrude into the range of the groove 325 (see FIG. 6A) in a state where the connection nut 320 is fastened to the connection nut fixing projection 502. Therefore, even when the jig 500 is lowered to immerse the connection nut 320 from the outer end surface 326 to the distance H in the predetermined solution 610, the connection nut fixing projection 502 is caused by the predetermined solution 610. The opening of the air vent hole 504 at the tip 503a is not blocked.

  Here, it returns to the description using FIG. 5 again.

  The plurality of uncoated connection nuts 320 set on the jig 500 in step S102 are lowered into the predetermined solution 610 (polyimide solution) from the outer end surface 326 of the connection nut 320 to the distance H by lowering the jig 500. Immerse (see step S103).

  At this time, as shown in FIG. 6A, the polyimide solution that has entered from the through-portion 323 pushes the air in the space 325a to the outside through the air vent hole 504, and uses the outer end surface 326 as a reference. To the height of the distance H.

  Thereby, as shown in FIG. 4, the electrolytic corrosion suppression film 400 includes a surface of the pressing portion 324 of the connection nut 320, an inner peripheral wall surface 323 a of the penetrating portion 323 connected to the surface of the pressing portion 324, and an inner peripheral wall surface thereof. The outer end surface 326 connected to the outer end surface 326 and the outer peripheral inclined surface 327 connected to the outer end surface 326 are covered with no gap, and the fixed range 328 of the hexagonal outer peripheral surface 329 connected to the outer peripheral inclined surface 327 (in side view) (Range of distance h along the central axis 321).

  Next, the jig 500 is raised, and the jig 500 with the connection nut 320 attached is removed from the jig lifting device and placed in a drying device (not shown) and dried at 180 ° C. (see step S104). ).

  Next, the jig 500 with the connection nut 320 attached is taken out from the drying device and attached again to the jig lifting device. Then, the jig 500 is lowered to be immersed in a predetermined solution 610 (a polyimide solution containing a fluororesin) from the outer end surface 326 of the connection nut 320 covered with the polyimide resin to a distance H (see step S105).

  Next, the jig 500 is raised, and the jig 500 with the connection nut 320 attached is removed from the jig lifting device, placed in a baking apparatus (not shown), and baked at 280 ° C. (step S106). reference).

  Next, the jig 500 with the connection nut 320 attached is taken out from the baking apparatus, and the connection nut 320 is removed from the jig 500 (step S107).

  Thus, the formation of the electrolytic corrosion suppression film 400 on the connection nut 320 is completed.

  Next, a sample in which the aluminum alloy tube member 310 is connected to the joint member 110A using the connection nut 320 on which the electrolytic corrosion suppression film 400 is formed, and a conventional connection nut 1320 is used to make the aluminum alloy tube member 310A. Samples in which the pipe member 310 is connected to the joint member 110A are prepared and subjected to a salt spray test, and the occurrence of electrolytic corrosion is compared. The results will be described with reference to Table 1.

  (1) First, a sample as a test object will be described.

  2 minutes (tube diameter φ6.35 mm), 3 minutes (tube diameter φ9.52 mm), and 4 minutes (tube diameter φ12.7 mm) aluminum alloy pipe member 310 are prepared. Samples prepared by tightening and connecting to a brass coupling member 110A with a specified torque by using a brass connection nut 320 on which the suppression film 400 is formed are prepared. Were taken as Example 1, Example 2, and Example 3.

  Similarly, the conventional connection nut 1320 is also made of aluminum alloy pipes of 2 minutes (tube diameter φ6.35 mm), 3 minutes (tube diameter φ9.52 mm), and 4 minutes (tube diameter φ12.7 mm). A member 310 is prepared, and each sample No. These were designated as Comparative Example 1, Comparative Example 2, and Comparative Example 3.

  In each of Examples 1 to 3 and Comparative Examples 1 to 3, in order to prevent test water from entering the inside of the pipe member 310 and the inside of the joint member 110A, the opening portion of the pipe member 310 and the joint The opening of the member 110A was completely closed.

  In addition, the arrangement angle of the test sample was arranged almost vertically in order to approximate the actual usage of the air conditioner outdoor unit.

  The formation range of the electrolytic corrosion suppression film 400 of the connection nut 320 in Examples 1 to 3 is the same as that of FIG. 4 except that the outer shape of the cross section by a plane perpendicular to the central axis 321 extends to the entire surface of the hexagonal outer peripheral surface 329. This is the same as the range described in.

  (2) Next, the conditions of the salt spray test will be described.

Test standard: Neutral salt spray test method defined in JIS Z 2371 Test condition: Sodium chloride concentration; 50 ± 5 g / L
Spray amount: 1.5 ± 0.5 mL / 80 cm ² / h
Test chamber temperature: 35 ± 2 ° C
Number of samples: 3 examples + 3 comparative examples Test time: 680 hours (3) Next, test results will be described based on Table 1.

表１に示す通り、実施例１〜３の何れについても、電食は確認できなかった。

As shown in Table 1, electrolytic corrosion could not be confirmed in any of Examples 1 to 3.

  In all of Examples 1 to 3, the flare inner surface 311b (see FIG. 3A) of the tube member 310 maintained the gloss of the aluminum alloy.

  Moreover, about Comparative Examples 1-3, the electrolytic corrosion could be confirmed in all the samples.

  In particular, in Comparative Example 1, the flared tip of the tube member 310 was broken by significant electric corrosion.

  From the above results, when connecting the aluminum alloy tube member 310 to the brass coupling member 110A using the brass connection nut 320 on which the electrolytic corrosion suppression film 400 of the present embodiment is formed, It was verified that it was possible to prevent the occurrence of dissimilar metal contact corrosion.

  Here, pure aluminum as a main component of the aluminum alloy that is the material of the pipe member 310 of the present embodiment is an example of the first metal of the present invention, and brass that is the material of the connection nut 320 of the present embodiment. Copper as the main component is an example of the second metal of the present invention.

  In the above-described embodiment, the electrolytic corrosion suppression film 400 has the outer end surface 326 on the penetrating portion 323 side of the connection nut 320 as a reference surface, and the pressing portion 324 and the groove portion 325 are formed along the central axis 321 from the reference surface. Although the case where the entire surface of the inner wall and the outer wall of the connection nut 320 included in the range of the distance H up to the boundary portion 324BL is covered has been described, the present invention is not limited to this, for example, the surface of the pressing portion 324 of the connection nut 320 The inner peripheral wall surface 323a of the penetrating portion 323 connected to the surface of the pressing portion 324 and the outer end surface 326 connected to the inner peripheral wall surface 323a may be covered without a gap. In short, the electrolytic corrosion suppression film 400 only needs to be formed on at least the wall surface in contact with the tube member 310 among the wall surfaces of the connection nut 320.

  Moreover, in the said embodiment, although the case where the electrolytic corrosion suppression film | membrane 400 was formed in the limited range of the connection nut 320 was demonstrated, not only this but the connection nut 320 is connected to the joint members 110A and 110B ( The electrolytic corrosion suppression film 400 may be formed over the entire inner wall surface and outer wall surface of the connection nut 320 as long as the tightening torque at the time of tightening to 210A, 210B) is not adversely affected.

  Moreover, although the said embodiment demonstrated the case where the connection nut 320 was immersed in the polyimide solution and the polyimide solution containing a fluororesin in the formation process of the electrolytic corrosion suppression film | membrane 400 (process S103 of FIG. 5, process) S105), but not limited to this, for example, the connection nut 320 is immersed in a solution of polyamic acid, which is a precursor of polyimide, and the solution is dried. After a desired film is obtained, the polyimide is imidized by heat treatment. A film may be formed.

  Moreover, in the said embodiment, although the case where a polyimide resin was used as an example of the resin material which has electrical insulation as a material of the electrolytic corrosion suppression film | membrane 400 was demonstrated, it is not restricted to this, For example, nylon, ethylene-vinyl alcohol Copolymerization may be used.

  In the above-described embodiment, the case where the jig 500 (see FIG. 6A and FIG. 6B) is used in the formation process of the electrolytic corrosion suppression film 400 has been described. Another jig (not shown) that has lattice-shaped through-holes formed in the surface of the cylindrical member in the vertical direction and the horizontal direction and that can be held by inserting a predetermined distance into the through-holes from the outer end surface 326 side of the connection nut 320 ), The connection nut 320 may be immersed in the predetermined solution 610 from the outer end surface 326 to a distance H by a method similar to the method described in FIG.

  Moreover, although the said embodiment demonstrated the case where the electrolytic corrosion suppression film | membrane 400 was formed by immersing the connection nut 320 in the predetermined solution 610, it is not restricted to this, For example, with respect to the connection nut 320, a spray apparatus The electrolytic corrosion suppression film 400 may be formed by spraying a predetermined solution 610 using, for example. Further, in this case, it is possible to prevent a film from being formed on the surface of the female screw portion 322 by screwing a dummy joint member into the female screw portion 322 of the connection nut 320.

  In this case, in the film forming step (S101 to S107) described with reference to FIG. 5, instead of the steps S103 and S105 by dipping, a predetermined solution 610 (for example, in the first spraying step) using a spray device or the like is used. A plurality of connection nuts set in the jig 500 (see FIG. 6A) are adopted by using a step of spraying a polyimide solution and using a polyimide solution containing a fluororesin in the second spraying step. The electrolytic corrosion suppression film 400 may be formed on the outer peripheral wall surface 320 and the inner peripheral wall surface excluding the surface of the female screw portion 322. In this case, the second spraying step may be omitted.

  In the above embodiment, the electrolytic corrosion suppression film 400 has been described as an electrically insulating film. However, the present invention is not limited to this. For example, a metal material powder and a resin material having a higher ionization tendency than an aluminum alloy are used. It may be a film having a sacrificial anticorrosive effect. In this case, as an example of a film having a sacrificial anticorrosive effect, for example, a connecting nut 320 is formed by using a material obtained by adding a resin as a binder to a flaked zinc powder and an aluminum material powder. In addition, the film may be formed by a dipping method or a spraying method using a spray device or the like. In the present specification, the term “aluminum material” is used as a term including both the case of pure aluminum and the case of aluminum alloy. In the case of this configuration, the reason why electrolytic corrosion is suppressed is as follows.

  That is, as shown in FIG. 3B, moisture can enter the gap 323b formed between the through portion 323 of the connection nut 320 made of brass and the pipe member 310 made of aluminum alloy, and sacrificial corrosion protection is performed. The inner peripheral wall surface 323a of the penetrating portion 323, on which a film having an effect is formed, can come into contact with the outer peripheral surface of the aluminum alloy tube member 310. When the aluminum material contained in the film having the sacrificial anticorrosive effect is pure aluminum, all metal materials contained in the film having the sacrificial anticorrosive effect, the material of the pipe member 310 made of aluminum alloy, and the connection made of brass When the nut 320 is arranged in the order of a material having a high ionization tendency to a low material, pure aluminum, zinc, an aluminum alloy, and brass are obtained.

  Therefore, pure aluminum having a larger potential difference due to a difference in ionization tendency is corroded by electrolytic corrosion earlier than the pipe member 310 made of aluminum alloy with respect to the connection nut 320 made of brass. Electric corrosion can be suppressed.

  Further, if the aluminum material contained in the film having the sacrificial anticorrosive effect is an aluminum alloy, the potential difference due to the difference in ionization tendency as compared with the tube member 310 made of aluminum alloy with reference to the connection nut 320 made of brass. Since zinc having a larger diameter is corroded by electrolytic corrosion first, electrolytic corrosion of the pipe member 310 can be suppressed.

  Moreover, according to the structure of the film having the sacrificial anticorrosive effect, the flaked metal powder is laminated with orientation, and the resin is interposed as a binder between the metal frames. Thereby, since moisture, oxygen, etc. cannot enter easily, aged deterioration of a membrane | film | coat can be suppressed.

  Moreover, since the resin film is further formed on the film having the sacrificial anticorrosive effect, the anticorrosive effect is further improved since it has electrical insulation.

  Moreover, although the said embodiment demonstrated the case where the connection nut of this invention and the piping set containing the connection nut were used for the refrigerant | coolant piping of an air conditioner, not only this but a refrigerator (refrigeration apparatus), for example You may use for connection of piping of other devices, such as.

  Moreover, although the said embodiment demonstrated the case where the connection nut of this invention and the piping set containing the connection nut were used for the refrigerant | coolant piping of an air conditioner, not only this but the connection nut of this invention, for example, The pipe member used for the circulation and transport of substances other than the refrigerant (except for those that promote contact corrosion of different metals) may be applied to a connection nut connected to a joint member having an opening, The piping set of the present invention includes a connection nut and a pipe member, and the pipe member has a first metal as a main component, and the connection nut mainly includes a second metal different from the first metal. You may apply to the piping set characterized by having as a component. Examples of the pipe member used for the circulation and transport of substances other than the refrigerant (except for those that promote contact corrosion of different metals) include medical gas / liquid pipes.

  Moreover, although the said embodiment demonstrated the case where the heat insulation tube 330 was included in addition to the connection nut 320 and the pipe member 310 as an example of the piping set of this invention, it is not restricted to this, For example, other piping sets As an example, the heat insulating tube 330 may not be included, and only the connection nut 320 and the pipe member 310 may be included.

  In the above embodiment, the connection nut 320, the outdoor unit side joint members 110A and 110B, and the indoor unit side joint members 210A and 210B are made of brass, and the pipe member 310 is made of an aluminum alloy. Although the case has been described, in short, if the pipe member has a first metal as a main component and the connection nut has a second metal different from the first metal as a main component, these members The material is not limited to the above embodiment, and any material may be used.

  Moreover, although the said embodiment demonstrated the case where the external shape of the AA cross section of the connection nut 320 was a hexagon, it is not restricted to this, For example, an external shape is circular and a tool fits in an opposing position. In other words, the outer shape of the AA cross section may be any shape as long as it can be tightened to connect the pipe member to the joint member. good.

  Further, in the above embodiment, when the air vent hole 504 is provided in the jig 500 and the connection nut 320 is immersed in the predetermined solution 610, the predetermined solution 610 is likely to enter the space 325a from the penetration portion 323. As described above, the case where the air in the space portion 325a is configured to escape to the outside has been described. However, the present invention is not limited to this. For example, in the drying step of step S104 illustrated in FIG. It is good also as a structure which has the function to send dry air into the space part 325a of the connection nut 320 using the part 504. FIG. As a result, the drying time in the space 325a of the connection nut 320 can be shortened and the clogging of the air vent hole 504 can be prevented.

  According to the connection nut and the piping set of the present invention, it is possible to suppress the contact corrosion of dissimilar metals without deteriorating workability. It is useful as a connection nut or a piping set used for piping or medical gas / liquid piping.

DESCRIPTION OF SYMBOLS 1 Air conditioner 2 House 100 Outdoor unit 200 Indoor unit 300 Refrigerant piping 300A Thick pipe member 300B Thin pipe member 320 Connection nut 322 Female thread part 323 Through part 323a Inner peripheral wall surface 324 Press part 324BL Boundary part 325 Groove part 326 Outer end face 327 Outer peripheral inclined surface 328 Fixed range 329 Hexagonal outer peripheral surface 400 Electric corrosion suppression film

Claims (6)

A connection nut for connecting a pipe member to a joint member having an opening,
In the connection nut, in a state in which the pipe member is connected to the joint member, at least a wall surface in contact with the pipe member is covered with a predetermined film among the wall surfaces of the connection nut. And connecting nut. The connection nut has an outer peripheral surface having a polygonal cross section, and has a cylindrical body that is open at both ends.
The connection nut is
An internal thread portion that is formed from one end portion inside the cylindrical body to the near end of the other end portion and is screwed with an external thread portion on the outer peripheral surface of the joint member;
A penetrating portion formed in the other end portion through which the tube member penetrates;
In order to press and connect the funnel-shaped inclined surface at the end of the tube member, which is formed between the inner peripheral wall surface of the penetrating portion and the female screw portion, to the outer peripheral edge of the opening of the joint member A pressing portion, and
The said predetermined film | membrane is formed in the outer peripheral surface of the said inner peripheral wall surface of the said penetration part, the said press part, and the said other end part side of the said connection nut at least. Connection nut. A connection nut according to claim 1 or 2,
The connection nut is provided with the pipe member provided so as to be arranged at both ends,
The pipe set, wherein the pipe member includes a first metal as a main component, and the connection nut includes a second metal different from the first metal as a main component.   The piping set according to claim 3, wherein the first metal is aluminum and the second metal is copper. The material of the pipe member is an aluminum alloy,
The material of the connection nut is brass,
The said predetermined film | membrane is a film | membrane which has a film | membrane which has electrical insulation, or a metal material powder and resin material with a high ionization tendency compared with the said aluminum alloy, It is characterized by the above-mentioned. Piping set.   The said pipe member is a pipe member for connecting the outdoor unit and indoor unit of an air conditioner via the said joint member and the said connection nut, and circulating a refrigerant | coolant of Claim 3-5 characterized by the above-mentioned. The piping set according to any one of the above.

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