JP2007162742A - Flareless type pipe joint and refrigerating cycle device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flareless type pipe joint for preventing the freezing of water in outside air after entering into the pipe joint, and to provide a refrigerating cycle device using the same. <P>SOLUTION: The flareless pipe joint comprises a joint body 1, a fastening nut 2, and a flareless type sleeve 3. The joint body 1 has a male screw portion 14 on the outer periphery to be threaded to the fastening nut 2, and an enlarged portion 12 behind the male screw portion 14, whose outer periphery is larger than the outer periphery of the male screw portion 14. The enlarged portion 12 has an end face 12a which is opposed to an end face 2a of the fastening nut 2 at a predetermined distance in the state of fastening the fastening nut 2. Between the end face 12a of the enlarged portion 12 and the end face 2a of the fastening nut 2 opposed thereto, a metal seal is formed which is communicating with the flareless sleeve 3 in the pipe joint via the male screw portion 14 and a female screw portion 22 to be threaded thereto for sealing an outside air moving passage. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a bite type pipe joint and a refrigeration cycle apparatus using the same, and more particularly, to a structure that prevents deterioration in sealing performance due to freezing of moisture in the air inside the pipe joint.

  Many pipe joints used for fluid pipes that allow fluid to flow inside are removable so that they can be easily replaced and repaired when pipe deterioration or fluid supply pipe deterioration occurs. It has been broken. Such pipe joints have various structures depending on the application.

  For example, in a refrigeration cycle apparatus such as an air conditioner in which a refrigerant flows in a fluid pipe, a flare type pipe joint has been conventionally used as a pipe joint. However, in the refrigeration cycle apparatus, the refrigerant is being changed to protect the natural environment on a global scale. In other words, the refrigerant is being replaced from a conventional chlorofluorocarbon refrigerant with a flammable alternative chlorofluorocarbon or a natural refrigerant such as carbon dioxide whose use pressure is high. However, some new refrigerants have higher operating pressures and others have combustibility. For this reason, in a refrigeration cycle apparatus using a new refrigerant, a bite type pipe joint that has been conventionally used for connecting a steel pipe through which a high-pressure fluid is circulated tends to be used. In addition, its development has been actively conducted. Such bite type pipe joints are described in Patent Document 1 and Patent Document 2, for example.

FIG. 4 shows an example of a bite type pipe joint known from these patent documents. As shown in FIG. 4, the bite type pipe joint generally includes a joint body 101, a fastening nut 102, and a bite type sleeve 103. The joint body 101 has a male screw portion 105 formed on the fastening nut side, that is, on the outer periphery of the pipe connection portion 104. The fastening nut 102 is formed in a cap shape, and has a female screw portion 106 that is screwed into the male screw portion 105 and a pressing taper surface 107 that presses the biting sleeve 103 against the end portion of the pipe connecting portion 104. Is formed. Further, the bite-in type sleeve 103 is composed of a back ferrule 103a and a front ferrule 103b in this example. The assembly of the bite-in type pipe joint is performed by firstly fitting the end of the bite-in type sleeve 103 on the joint body side to the guide taper surface 108 formed at the end of the pipe connection part 104 and fastening the bite-in type sleeve 103. The nut side end portion is in a state of facing the pressing taper surface 107 of the fastening nut 102. Next, the internal thread portion 106 of the fastening nut 102 is screwed into the external thread portion 105 of the joint body 101. In this manner, the fastening nut 102 is screwed into the joint body 101, whereby the pressing taper surface 107 of the fastening nut 102 presses the biting sleeve 103 against the guide taper surface 108 of the pipe connection portion 104. As a result, the back ferrule 103a and the front ferrule 103b cooperate with each other to bite into the connecting pipe 109 to prevent the connecting pipe 109 from being detached and to obtain a high sealing performance. FIG. 4 is a state diagram after the fastening nut 102 is fastened and the connection is completed.
JP 2003-74769 A JP 2005-36947 A

  By the way, in the bite type pipe joint in which the fastening nut 102 is fastened and the connection pipe 109 is connected as described above, the space 110 generated on the outer peripheral side of the bite type sleeve 103 is an outside air entrance passage indicated by a broken line arrow in FIG. 111 communicates with the outside air. The outside air entry passage 111 referred to here is a passage that communicates with the outside air around the pipe joint through a threaded portion between the male screw portion 105 of the pipe connecting portion 104 and the female screw portion 106 of the fastening nut 102. Further, the bite type pipe joint after connection changes the temperature of the pipe joint itself along with the temperature change of the fluid such as the refrigerant, but when the temperature of the pipe joint decreases, the moisture in the air in the space 110 inside the pipe joint Condensation occurs, and accordingly, moisture in the outside air enters the inside of the pipe joint through the above-described outside air entrance passage 111. Further, when the temperature of the pipe joint becomes zero degrees or less due to a change in fluid temperature or a change in the outside air temperature, dew condensation water or moisture in the air freezes in the pipe joint, resulting in volume expansion. When this state is repeated, the volume expansion force of the frozen ice acts on the bite-in sleeve 103 and deforms the bite-in sleeve 103. In this way, when the bite-in type sleeve 103 is deformed, the sealing performance of the pipe joint is lowered and refrigerant leakage occurs.

  The above is described by taking an example of a bite type pipe joint used in a refrigeration cycle apparatus such as an air conditioner. However, the above-mentioned problem of moisture freezing in the pipe joint is caused by a change in the temperature in the pipe joint due to a change in the atmospheric temperature, etc. in fields other than the refrigeration cycle apparatus such as an air conditioner. May freeze and seal performance may deteriorate.

  The present invention has been made paying attention to such problems existing in the prior art. That is, an object of the present invention is to provide a bite type pipe joint that prevents moisture in the outside air from entering the pipe joint and freezing, and a refrigeration cycle apparatus using the same.

  The present invention has been made in view of the above problems. The bite type pipe joint according to the present invention includes a joint body, a fastening nut, and a bite type sleeve. The joint main body has a male screw part that screwes a fastening nut on the outer periphery, and an enlarged part having a larger cross section than the outer periphery of the male screw part behind the male screw part. The enlarged portion is formed with an end face that faces the end face of the fastening nut at a predetermined distance when the fastening nut is fastened. And, in order to seal the outside air entrance passage leading to the bite type sleeve inside the pipe joint via the male screw part and the female screw part screwed between the end faces of the enlarged part and the end face of the fastening nut facing each other The metal seal is formed.

  According to the bite type pipe joint configured as described above, the space generated on the outer peripheral side of the bite type sleeve has a gap between the male screw part and the female screw part and the gap between the end face of the enlarged part and the end face of the fastening nut. An outside air entrance passage that communicates with outside air through is sealed with a metal seal at the inlet. Therefore, even if the temperature of the pipe joint itself is lowered, the outside air entrance passage is sealed at the inlet portion, so that moisture hardly freezes. Therefore, it is possible to avoid the conventional problem that the bite type sleeve is deformed due to the freezing of moisture inside the pipe joint and the sealing performance is lowered.

  In the above, the metal seal is formed so as to be sealed after the bite type sleeve is bitten into the connecting pipe to be connected. Since it is formed in this way, the possibility that the bite-in sleeve is insufficiently bited and the sealing performance is insufficient is avoided. In addition, if the timing for the bite type sleeve to bite into the connection pipe to be connected and the timing for the metal seal to be sealed are adjusted in this way, the operation should be carried out based on the sudden increase in the tightening torque of the fastening nut. It can be carried out. That is, when the timing adjustment as described above is performed, it means that the metal seal is sealed when the tightening torque of the fastening nut increases rapidly. This also means that the bite-type sleeve has been bite into the connecting pipe to be connected immediately before. Therefore, the management of the tightening torque of the fastening nut is reliably performed.

  Further, when the enlarged portion is a nut portion whose outer peripheral shape is formed in a nut shape, an end face necessary for the configuration of the mechanical seal can be formed without changing the conventional basic configuration, so that the bite type pipe There is no need to complicate the structure of the joint.

  Further, the metal seal can be formed by an end face of the fastening nut and an end face of the joint body, and a protrusion formed on any one of the end faces. If comprised in this way, a metal seal can be formed easily.

  The protrusion is preferably formed on the end face on the fastening nut side. The protruding portion can be formed on the end face of the enlarged portion of the joint body, but the tip of the protruding portion may be damaged during parts transportation or connection work. In this case, the replacement of the joint body is often not easy. In this regard, when the protruding portion is formed on the fastening nut side, the fastening nut can be replaced, so that the parts can be easily replaced.

  Moreover, it is preferable to form this protrusion part so that the circular shape centering on the central axis of the said pipe joint may be drawn in the end surface at the side of a fastening nut. In this way, it becomes easy to perform a uniform seal at the tip of the protrusion. Moreover, since it is a simple shape, manufacture is also easy.

  Moreover, it is preferable that this protrusion has a sharp tip. By doing in this way, since it can be set as the seal structure of line contact, a sealing performance can be improved.

  Moreover, it is preferable to form the cross-sectional shape of this projection part in the substantially triangular shape with a sharp point. With such a cross-sectional shape, it is possible to obtain the above-described seal structure by line contact while being easy to manufacture.

  The refrigeration cycle apparatus according to the present invention uses the bite type pipe joint having the above-described configuration. In the case of a refrigeration cycle apparatus, the temperature of the pipe joint changes drastically, and depending on the location of use, the temperature of the pipe joint itself is often less than or equal to zero degrees. For this reason, in the pipe joint used for the refrigeration cycle apparatus, there is a high possibility that moisture will freeze in the pipe joint. Therefore, by using the pipe joint as in the present invention, it is possible to reliably prevent the deterioration of the seal performance of the pipe joint due to freezing of moisture in the pipe joint.

  According to the bite type pipe joint according to the present invention, the outside air entrance passage leading to the inside of the pipe joint in which the bite type sleeve is accommodated via the male screw part and the female screw part to be screwed is sealed by the metal seal at the inlet part. Therefore, even if the temperature of the pipe joint itself changes, the moisture hardly freezes. Therefore, it is possible to avoid the problem that the bite type sleeve is deformed due to moisture icing inside the pipe joint and the sealing performance is deteriorated.

  Hereinafter, a bite type pipe joint according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a sectional view of a bite type pipe joint according to an embodiment of the present invention. As shown in FIG. 1, the bite type pipe joint according to the present embodiment is used as a joint of a refrigerant pipe for a refrigeration cycle apparatus, and includes a joint body 1, a fastening nut 2, and a bite type sleeve 3. And. In this bite type pipe joint, the fixed side pipe 4 is connected to the base end side (non-connection end side) of the joint body 1 by brazing or the like, and the connection pipe 5 to be connected to the connection end of the joint body 1 is removed. It is possible to connect. Further, the bite type pipe joint of this embodiment is formed of a copper alloy.

  As shown in FIG. 1, the joint body 1 includes a pipe connection portion 11 that removably connects the connection pipe 5 by removing the fastening nut 2, and a pipe formed by being connected to the pipe connection section 11. The outer peripheral enlarged portion 12 is larger than the outer periphery of the connecting portion 11, and the socket portion 13 is formed following the enlarged portion 12.

  As shown in FIG. 1, the pipe connecting portion 11 is formed with a male screw portion 14 for screwing the fastening nut 2 on the outer periphery. Moreover, the pipe connection part 11 is provided with the pipe connection port 15 for inserting the connection pipe 5 in order to connect the connection pipe 5 which should be connected detachably in a predetermined position. The connecting end portion of the tube connecting portion 11 is formed with a guide taper surface 18 that guides the leading end portion 3a of the biting sleeve 3 so as to bite into the connecting tube 5 side. The guide taper surface 18 is reduced in diameter from the end surface 11 a on the connection end side toward the pipe connection port 15, and is connected to the pipe connection port 15 inside the pipe connection portion 11.

  The enlarged portion 12 is a nut portion formed in a nut shape, and may be a nut-shaped portion usually formed in a conventional bite type pipe joint. The end surface 12a on the fastening nut side of the enlarged portion 12 is formed to face the end surface 2a of the fastening nut 2 with a predetermined distance when the fastening nut 2 is fastened to the pipe connecting portion 11. . In addition, a pipe connection port 16 for connecting the fixed side pipe 4 to a predetermined position is provided at the center from the enlarged part 12 to the socket part 13 so that the fixed side pipe 4 can be brazed to the socket part 13. ing. In addition, a communication hole 17 that connects between the pipe connection port 15 and the pipe connection port 16 is formed in the central portion from the enlarged portion 12 to the pipe connection portion 11.

  The fastening nut 2 has a nut shape that is long in the central axis direction, and a cylindrical space 21 that opens to the pipe connecting portion 11 side is formed inside. Further, the fastening nut 2 is formed with a side wall 22 that forms the side surface of the cylindrical space 21 at the end of the space 21, and a through hole 23 through which the connecting pipe 5 passes is formed in the side wall 22. The inner surface of the side wall 22 is formed as a pressing surface 25 that presses a side surface 32 of a bite type sleeve 3 to be described later.

  Furthermore, an internal thread portion 24 that is screwed into the external thread portion 14 of the pipe connection portion 11 is formed on the inner peripheral surface that forms the cylindrical space 21 of the fastening nut 2. Further, a projecting portion 26 is formed on the end surface 2 a of the fastening nut 2 on the pipe connecting portion 11 side. The protrusion 26 has a triangular cross section with a sharp tip. Further, as shown in the side view of the fastening nut in FIG. 2, the protruding portion 26 is formed to draw a circle on the end surface 2 a of the fastening nut 2. The protrusion 26 constitutes a mechanical seal that seals the outside air entrance passage according to the present invention by bringing the tip portion into contact with the end surface 12 a of the enlarged portion 12. In this case, the outside air entry passage is a bite type through a gap formed between the end surface 2a of the fastening nut 2 and the end surface 12a of the enlarged portion 12 via a threaded portion of the male screw portion 14 and the female screw portion 24. A passage communicating with the space 21 formed on the outer peripheral side of the sleeve 3 is referred to.

  As shown in FIG. 1, the bite type sleeve 3 is disposed so as to be interposed between the guide tapered surface 18 of the pipe connecting portion 11 and the pressing surface 25 of the fastening nut 2. Further, the bite type sleeve 3 is formed in a ring shape so that the connecting pipe 5 is fitted and inserted as shown in FIG. Further, the bite type sleeve 3 has a cross-sectional shape in the central axis direction of the pipe joint of the element forming the ring shape, as shown in FIG. 1, a contact surface 31 that contacts the connecting pipe 5, and one end of the fastening nut 2 A side surface 32 perpendicular to the central axis of the pipe joint, and a slope 33 extending from the upper part of the vertically formed side surface 32 toward the pipe connection portion 11 and toward the outer periphery of the connection pipe 5. It consists of a substantially right triangle. Further, the tip 33 a of the inclined surface 33 forming a substantially right triangle functions as a tapered surface corresponding to the guide tapered surface 18 formed on the side of the fastening nut of the pipe connecting portion 11. By forming in this way, the front-end | tip part 3a of the bite-in type sleeve 3 functions as a bite-in part.

  The bite type pipe joint according to the present embodiment configured as described above is connected to the connection pipe 5 to be connected as follows. In the following description, it is assumed that the fixed side pipe 4 is connected to the joint body 1 in advance by brazing.

  First, the distal end portion of the connection pipe 5 is passed through the through hole 23 of the fastening nut 2, and the fastening nut 2 is externally attached to the connection pipe 5. Next, the bite-in sleeve 3 is held in the joint body 1 so that the tip 33a of the inclined surface 33 of the bite-in sleeve 3 faces the guide taper surface 18 of the pipe connection part 11 of the joint body 1. And the front-end | tip part of the connecting pipe 5 by which the fastening nut 2 was armored is inserted in the piping connection port 15 of the pipe connecting part 11. Next, the female screw portion 24 of the fastening nut 2 is screwed into the male screw portion 14 on the outer periphery of the pipe connecting portion 11. In this way, the fastening nut 2 is tightened. By this tightening, the distal end portion 33 a of the inclined surface 33 of the bite type sleeve 3 is strongly pressed against the guide tapered surface 18 of the pipe connecting portion 11. By this strong pressing, the distal end portion 3 a of the bite type sleeve 3 bites into the surface of the connecting pipe 5 under the guide action of the guide taper surface 18.

  In the bite type pipe joint according to the present invention, when the leading end portion 3a of the bite type sleeve 3 completes biting into the surface of the connecting pipe 5, the protruding portion 26 of the fastening nut 2 is formed on the end surface 12a of the enlarged portion 12. It is set in advance so as to abut. Further, when the protruding portion 26 comes into contact with the end surface 12a, the tightening torque for tightening the fastening nut 2 by a physical action increases rapidly.

  Therefore, the connection work in the present invention is completed when the tightening torque is increased and the fastening work of the fastening nut 2 is finished. Further, by completing such a series of operations, the leading end portion 3a of the bite type sleeve 3 is securely bited into the surface of the connection tube 5 and the connection operation of the connection tube 5 to be connected is completed. At the same time, the outside air entry passage inside the bite type pipe joint is mechanically sealed by the cooperative operation of the projection 26 and the end surface 12a of the enlarged portion 12.

According to the present embodiment configured as described above, the following effects can be obtained.
(1) A gap between the opposing end surfaces 2a and 12a, an external air entrance passage that leads to the space 21 inside the pipe joint in which the bite type sleeve 3 is housed via the male screw portion 14 and the female screw portion 24 that are screwed together, Sealed with a metal seal at the inlet. Therefore, even if the temperature of the pipe joint itself changes, the water 21 is hardly frozen in the space 21 inside the pipe joint. Therefore, it is possible to avoid the problem that the bite type sleeve 3 is deformed due to icing of water inside the pipe joint and the sealing performance is deteriorated.

  (2) Since the metal seal is formed so as to be sealed after the bite type sleeve 3 is bitten into the connecting pipe 5 to be connected, the bite type sleeve 3 is insufficiently bitten and the sealing performance is insufficient. The possibility of becoming is avoided. In addition, since the timing at which the bite type sleeve 3 is bitten into the connecting pipe 5 to be connected and the timing at which the metal seal is sealed are adjusted in this way, a rapid increase in the tightening torque of the fastening nut 2 is taken as a guide. Work. Thereby, management of the tightening torque of the fastening nut 2 can be reliably performed.

  (3) Since the enlarged portion 12 is a nut portion whose outer peripheral shape is formed in a nut shape, the end surface 12a necessary for the configuration of the mechanical seal can be formed without changing the conventional basic configuration. Therefore, it is not necessary to complicate the configuration of the bite type pipe joint.

  (4) Since the metal seal is formed by the protrusion 26 formed on the end surface of the fastening nut 2 and the end surface 12a of the enlarged portion 12, the metal seal can be easily formed. Further, since the protruding portion 26 is formed on the end face of the fastening nut 2, the joint body 1 does not need to be replaced even if the tip of the protruding portion 26 is damaged during parts transportation or connection work. It is only necessary to replace the fastening nut 2. Therefore, replacement of parts in this case is easy.

  (5) Since the protruding portion 26 is formed so as to draw a circle centered on the central axis of the pipe joint on the end face on the fastening nut 2 side, a uniform seal can be performed at the tip portion of the protruding portion 26. . Moreover, since it is a simple shape, manufacture is also easy.

(6) Since the protrusion 26 has a shape with a sharp tip, the tip is brought into line contact with the end surface 12a, and good sealing performance can be obtained.
(7) Since the projecting portion 26 has a substantially triangular shape with a pointed cross section, the sealing structure by the above-described line contact can be obtained while being easy to manufacture.

  (8) In the case of the refrigeration cycle apparatus, the temperature of the pipe joint changes greatly, and depending on the place of use, the temperature of the pipe joint itself often tends to be less than or equal to zero degrees. For this reason, in the pipe joint used for the refrigeration cycle apparatus, there is a high possibility that moisture will freeze in the pipe joint. However, in the refrigeration cycle apparatus in which the refrigerant pipe is connected using the bite type pipe joint according to the present embodiment, it is possible to reliably prevent a decrease in the seal performance of the pipe joint due to freezing of moisture in the pipe joint.

The above embodiment can be modified as follows.
(1) In the above embodiment, the protrusion 26 constituting the mechanical seal of the outside air entrance passage is formed on the end surface 2a of the fastening nut 2, but this is formed on the end surface 12a of the enlarged portion 12. Also good. FIG. 3 shows an example. In this figure, the same components as those in the above embodiment are denoted by the same reference numerals, and the description thereof is omitted. In FIG. 3, a protrusion 19 is formed on the end surface 12 a of the enlarged portion 12. And the mechanical seal which seals an external air approach channel | path is comprised because the front-end | tip part of the projection part 19 contact | abuts to the end surface 2a of the fastening nut 2. FIG. The shape of the protrusion 19 is the same as that of the protrusion 26 according to the embodiment.

  In the case of this modification, when the tip of the projection 19 is damaged during parts transportation or connection work, the joint body 1 needs to be replaced as compared with the case of the above embodiment. There are difficulties. However, with respect to other points, the same operational effects as in the case of the first embodiment can be obtained.

  (2) In the above-described embodiment and the above-described modification, the cross-sectional shape of the protrusions 26 and 19 is formed in a triangular shape, but may be a partial circle such as a semicircle. In this case, since the tip is rounded, there is an advantage that handling is safe without being injured by the protrusion during work. However, since the tip cannot be shaped sharply, the sealing performance tends to be inferior to that in the first embodiment.

  (3) The end surface with which the projections 26 and 19 abut is required to have high processing accuracy of surface characteristics such as flatness and flatness. Accordingly, without increasing the overall processing accuracy of the end faces 2a and 12a, only the portion where the protrusions 26 and 19 abut is raised one step above the surroundings, and only this raised surface is finished with increased processing accuracy. Also good. In addition, the manufacturing cost can be reduced by doing so.

(4) The material forming the bite type pipe joint may be iron or light iron alloy other than the above-mentioned copper-based alloy.
(5) Moreover, although the bite type pipe joint according to the above embodiment is for a refrigeration cycle apparatus, it can also be used as a pipe joint for other applications.

It is sectional drawing of the bite type pipe joint which concerns on embodiment of this invention. It is a side view of the fastening nut in the bite type pipe joint. It is sectional drawing of the bite type pipe joint which concerns on a modification. It is a fragmentary sectional view of the bite type pipe joint concerning a conventional example.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Joint main body, 2 ... Fastening nut, 2a, 12a ... End face, 3 ... Biting-type sleeve, 3a ... Tip part, 5 ... Connection pipe, 11 ... Pipe connection part, 12 ... Expansion part, 14 ... Male thread part, 19, 26 ... Projection part, 24 ... Female thread part.

Claims (9)

  In a bite type pipe fitting having a joint body, a fastening nut, and a bite type sleeve, the joint body has a male threaded portion in which a fastening nut is screwed to the outer circumference, and an outer circumference larger than the outer circumference of the male threaded portion behind the male threaded portion. The enlarged portion is formed with an end surface facing the end surface of the fastening nut at a predetermined distance when the fastening nut is fastened, and further, between the facing end surfaces. A bite type pipe joint characterized in that a metal seal is formed for sealing an outside air ingress passage leading to a bite type sleeve inside the pipe joint through the male screw part and the female screw part to be screwed together.   The bite type pipe joint according to claim 1, wherein the metal seal is formed so as to be sealed after the bite type sleeve is bitten into the connecting pipe to be connected.   The bite type pipe joint according to claim 1 or 2, wherein the enlarged portion is a nut portion having an outer peripheral shape formed in a nut shape.   The bite type pipe joint according to any one of claims 1 to 3, wherein the metal seal is formed of a protrusion formed on one of an end face of a fastening nut and an end face of a joint body.   5. The bite type pipe joint according to claim 4, wherein the protrusion is formed on an end face on a fastening nut side.   6. The bite type pipe joint according to claim 5, wherein the projecting portion is formed so as to draw a circular shape centering on a central axis of the pipe joint on an end face on a fastening nut side.   The bite type pipe joint according to any one of claims 4 to 6, wherein the protrusion is formed in a shape having a sharp tip.   The bite type pipe joint according to claim 7, wherein a cross-sectional shape of the protrusion is formed in a substantially triangular shape with a sharp tip.   A refrigeration cycle apparatus using the bite type pipe joint according to any one of claims 1 to 8.

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