JP2009168127A - Double tube joint structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a passage formed of an inner tube and an outer tube from being narrowed due to seal material when double tubes are connected to each other. <P>SOLUTION: A first double tube 10 and a second double tube 20 are respectively provided with outer tubes 11 and 21, inner tubes 12 and 22, and supports 13 and 23 supporting them in a concentric state. The inner tubes 12 and 22 on the depth of opening ends are connected to each other by means of connecting joint parts 14 and 24 for working on the outer tube 11 and 21. The connecting joint parts 14 and 24 are directly coupled with the inner tubes 12 and 22, and are engaged with each other outward of the inner diameter of the inner tubes 12 and 22, so that inner tube passages are not narrowed. Connection parts of the outer tubes 11 and 21 corresponding to the connection parts of the inner tubes 12 and 22 are also deflected outward of their inner diameter, so that the passage formed between the outer tube and the inner tube is secured. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a double pipe joint structure, and in particular, a double pipe capable of connecting a double pipe that circulates a high-pressure refrigerant and a low-pressure refrigerant at the same time in a refrigeration cycle of an automotive air conditioner while maintaining the double pipe structure. It relates to a joint structure.

  In an automotive air conditioner, generally, a compressor, a condenser, and a receiver dryer are installed in an engine room, an evaporator is installed in a vehicle compartment, and an expansion valve is a partition wall or compartment that separates the vehicle compartment and the engine room. It is installed in the passenger compartment. In the refrigeration cycle, basically, a compressor, a condenser, a receiver dryer, an expansion valve, and an evaporator are piped so that the refrigerant flows in this order, and the refrigerant leaving the evaporator returns to the compressor. In such a refrigeration cycle, an internal heat exchanger that performs heat exchange between a high-temperature / high-pressure refrigerant introduced into an expansion valve and a low-temperature / low-pressure refrigerant sucked into a compressor is known.

  The internal heat exchanger cools high-temperature and high-pressure refrigerant introduced into the expansion valve with low-temperature and low-pressure refrigerant sucked into the compressor, and introduces low-temperature and low-pressure refrigerant sucked into the compressor into the expansion valve. Since it is overheated by the high-temperature and high-pressure refrigerant that is generated, it has the function of increasing the efficiency of the refrigeration cycle.

  As such an internal heat exchanger, without providing a dedicated heat exchanger, the inlet side pipe of the expansion valve and the outlet side pipe of the evaporator are made into a double pipe, and the inner pipe, the inner pipe and the outer pipe It is possible to configure by piping so that a high-temperature / high-pressure refrigerant and a low-temperature / low-pressure refrigerant flow through the annular passage. However, since the internal heat exchanger using a double pipe is inferior in performance as a heat exchanger, it is considered that the shortage of heat exchange can be covered by increasing the length of the double pipe. Depending on the vehicle, when the piping distance between the partition wall separating the vehicle compartment from the engine room and the expansion valve is short, it is necessary to extend the double pipe into the engine room via the partition wall. For the convenience of assembling the piping to the vehicle, the double pipe in the vehicle compartment and the double pipe in the engine room are separately piped, and then the double pipes are connected to each other at the partition wall.

  This double pipe is connected to the end of the double pipe by brazing a branching part that branches into a high-temperature / high-pressure pipe and a low-temperature / low-pressure pipe, and a block-shaped female or male joint. At this position, the female joint and the male joint are fitted and bolted together.

Such a double pipe connection method is expensive because the joint member attached to the tip of the double pipe is expensive, and a double pipe joint structure that can connect the double pipe as it is is proposed. (For example, refer to Patent Document 1). According to this double pipe joint structure, the inner pipes of the double pipes are connected by separate connecting inner pipes with O-rings fitted to the outer circumferences of both ends, and the outer pipes are connected to their tip portions. The double pipes are connected to each other by processing so as to be fitted to each other and fixing the fitted part from the outside with a fastening member. The fitting portion between the outer tubes is sealed with an O-ring.
Japanese Patent Laying-Open No. 2004-270928 (FIG. 14)

  In the above-mentioned double pipe joint structure, both ends of the connecting inner pipe are inserted into the inner pipe on the connection side of the two double pipes, and the inner pipes are connected to each other. Yes. The O-ring is fitted in a fitting groove formed at the tip of the connecting inner pipe and sealed with the inner wall of the inner pipe. The fitting groove for the O-ring is formed by denting the inner pipe for connection over the entire circumference, so that the inner passage of the inner pipe for connection becomes narrow and a throttle portion is formed. There was a problem.

  This invention is made | formed in view of such a point, and it aims at providing the double pipe joint structure which does not produce a throttle part in the connection site | part of double pipes.

  In the present invention, in order to solve the above problem, in the double pipe joint structure in which the first double pipe and the second double pipe each having a coaxial inner pipe and an outer pipe are connected, In the double pipe and the second double pipe, a connecting portion of the outer pipe projects in a cylindrical processing region protruding outward in the axial direction from the inner pipe at a position outside the inner diameter of the outer pipe. Formed by processing into shapes that can be fitted to each other, and the connecting portion of the inner tube can be fitted to each other at a position within the region of the connecting portion of the outer tube and outside the inner diameter of the inner tube. There is provided a double pipe joint structure characterized in that a cylindrical connecting joint portion having a shape is coupled to the tip of the inner pipe.

  According to such a double pipe joint structure, each of the first double pipe and the second double pipe has a cylindrical connecting joint portion directly coupled to the inner pipe of the first double pipe and the second double pipe. The factor which narrows is eliminated. In addition, the connecting part of the outer pipe is processed into a shape that can be fitted to each other at a position outside the inner diameter, and the connecting joint that is coupled to the inner pipe can also be fitted to each other at a position outside the inner diameter of the inner pipe. By processing into a simple shape, the passage formed between the outer tube and the inner tube is not narrowed.

  In the double pipe joint structure having the above configuration, the connection joint portion that connects the inner pipe in the outer pipe is directly coupled to the inner pipe without using a seal ring so that the inner pipe passage is not narrowed. With respect to the mutual connection, the outer tube and the inner tube can be fitted to each other at a position outside the inner diameter of the inner tube, and the connecting portion of the outer tube can also be fitted to each other at a position outside the inner diameter. There is an advantage that the passage between the pipes can be made as narrow as possible.

  In addition, since the tip of the connecting joint of the inner pipe protrudes outward from the end face of the outer pipe, of course, when connecting the outer pipes, the connecting joint parts of the inner pipe are fitted to each other before that. Even when joining, the fitting state can be directly confirmed by visual observation, and workability at the time of assembly can be improved.

Hereinafter, the embodiment of the present invention will be described in detail with reference to the drawings, taking as an example the case where the present invention is applied to a connecting portion of a double pipe functioning as an internal heat exchanger in a refrigeration cycle of an automotive air conditioner.
1 is a cross-sectional view showing a connection-side end structure of a double pipe, FIG. 2 is a cross-sectional view of the double pipe, and FIG. 3 is a cross-sectional view showing a double pipe joint structure.

  In the present embodiment, high-temperature and high-pressure piping that is piped from the receiver dryer in the engine room to the expansion valve in the vehicle compartment in the refrigeration cycle of the air conditioner for automobiles, and from the evaporator in the vehicle compartment to the compressor in the engine compartment. A part of the low-temperature and low-pressure piping to be piped has a double pipe structure, and the first double pipe 10 piped in the engine room and the second double pipe 20 piped in the passenger compartment are the engine. It is assumed that a connection is made between the room and the passenger compartment.

  As shown in FIG. 2, the first double pipe 10 and the second double pipe 20 include outer pipes 11 and 21, inner pipes 12 and 22, and struts 13 and 23 that support them. And has a coaxial double tube structure. In this example, the three support pillars 13 and 23 are evenly arranged in the circumferential direction between the outer pipes 11 and 21 and the inner pipes 12 and 22, but the present invention is not limited to this. What is necessary is just to maintain the path | route which flows a refrigerant | coolant between the outer pipes 11 and 21 and the inner pipes 12 and 22, as the 11 and 21 and the inner pipes 12 and 22 can maintain the concentric state. The first double tube 10 and the second double tube 20 are preferably made of a hollow extruded material integrally formed by hollow extrusion.

  The first double pipe 10 has a male joint structure in which an end of such a hollow extruded material is processed and a connection joint 14 is joined to the inner pipe 12. That is, the hollow extrusion molding material first forms a cylindrical processing region by removing the inner tube 12 and the struts 13 that hinder the processing from the end surface side to the region necessary for processing the outer tube 11, and further connects The struts 13 are removed to ensure a region where the joint portion 14 is coupled. Thereafter, the cylindrical processing region is processed by a press or the like to form the expanded pipe portion 15, the bead portion 16 for locking with the second double tube 20, and the sealing material mounting portion 17. In this way, the expanded tube portion 15, the bead portion 16, and the sealing material mounting portion 17 necessary for connecting the outer tube are expanded outside the inner diameter of the outer tube 11 by expanding the cylindrical processing region so as not to interfere with the refrigerant passage. Formed. And the cylindrical connection coupling part 14 is couple | bonded by being externally fitted by the front-end | tip of the inner tube 12. As shown in FIG. The connecting joint portion 14 has such a length that the tip extends outward from the end face of the processed outer tube 11 in a state of being coupled to the inner tube 12, and a seal is provided in the vicinity of the tip. A material mounting groove 18 is provided around.

  An adhesive such as a screw lock material used to prevent loosening of the screw is applied to the fitting portion between the connection joint portion 14 and the inner tube 12, whereby the connection joint portion 14 and the inner tube 12 are hermetically sealed. It is fixed to. Alternatively, the connection joint portion 14 can be hermetically coupled to the inner tube 12 by fitting the connection joint portion 14 to the tip of the inner tube 12 so that the inner tube 12 is press-fitted into the connection joint portion 14. Can do.

  Similarly to the case of the first double pipe 10, the second double pipe 20 has a female joint structure in which the end of the hollow extruded material is processed and the connection joint 24 is joined to the inner pipe 22. I have to. That is, in the hollow extruded material, first, the inner tube 22 and the column 23 are removed from the end surface side to a region necessary for processing the outer tube 21, and further, the column 23 is secured in order to secure a coupling region of the connection joint portion 24. Is removed. Thereafter, the distal end portion of the outer tube 21 is processed by a press or the like to form the expanded portions 25 and 26. The pipe expansion part 25 has an inner diameter that allows the seal material mounting part 17 formed at the tip of the outer pipe 11 of the first double pipe 10 to enter, and the pipe expansion part 26 has the first double pipe 10. It has the same outer diameter as the bead portion 16 formed in the outer tube 11 of the tube 10. The stepped portion 27 at the boundary between the expanded tube portion 25 and the expanded tube portion 26 is used for locking with the first double tube 10. The connection joint portion 24 is coupled to the tip of the inner tube 22. The connecting joint portion 24 has such a length that the tip is extended outward in the axial direction from the end face of the processed outer tube 21 in a state of being coupled to the inner tube 22, and the tip side is expanded. The expanded pipe 28 has an inner diameter that allows the connection joint 14 of the first double pipe 10 to enter. The pipe expansion portion 28 of the connection joint portion 24 is more than the pipe expansion portion 26 at the distal end portion of the outer tube 21 in order to receive the connection joint portion 14 whose tip protrudes from the end face of the outer tube 11 of the first double pipe 10. The connecting joint portion is long until the outer tube 11 is completely inserted into the outer tube 21 even after the connecting joint portion 14 is inserted into the connecting joint portion 24 at the time of connection. 24 has a length capable of guiding the connecting joint portion 14.

The fitting portion between the connection joint portion 24 and the inner tube 22 is airtightly fixed by an adhesive, or the connection joint portion 24 is fitted to the inner tube 22 by press-fitting.
The male first double tube 10 formed as described above is connected to the female second double tube 20 in the vicinity of the fitting hole of the partition wall. At that time, as shown in FIG. 3, the first double pipe 10 has the O-ring 31 attached to the sealing material mounting portion 17 of the outer pipe 11, and O in the sealing material mounting groove 18 of the connection joint portion 14. After mounting the ring 32, the connection with the second double pipe 20 is started.

  First, the connection joint part 14 of the first double pipe 10 to be connected and the connection joint part 24 of the second double pipe 20 to be connected both protrude outward in the axial direction from the end surfaces of the outer pipes 11 and 21. Therefore, when the connecting joint portion 14 of the first double pipe 10 is inserted into the connecting joint portion 24 of the second double pipe 20, it can be performed while visually confirming. Thereafter, the outer pipe 11 of the first double pipe 10 is inserted into the outer pipe 21 of the second double pipe 20, but these outer pipes 11 and 21 are outside the connection joint portions 14 and 24. Of course, the connection work of the outer tubes 11 and 21 can be performed while visually confirming.

  Since the expanded pipe portion 28 of the connection joint portion 24 is formed longer than the distance at which the outer tube 11 is inserted into the outer tube 21, the outer tube 11 is moved to the outer tube 21 after the connection joint portion 14 is first inserted. Until the insertion is completed, visual confirmation cannot be performed, but the sealing by the O-ring 32 is surely continued. As for the O-ring 31, since the insertion distance of the outer tube 11 to the outer tube 21 is short, connection work can be performed while checking the seal state. After the first double pipe 10 is inserted into the second double pipe 20 as described above, the first double pipe 10 and the second double pipe 20 are locked by the pipe clamp 40. The

FIG. 4 is a perspective view showing an example of a pipe clamp.
A pipe clamp 40 that connects the first double pipe 10 and the second double pipe 20 includes a first locking member 41 and a second locking member 42 each having a substantially semicircular arc shape, and a fixing pin 43. And. The first locking member 41 and the second locking member 42 have a hinge portion at one end in the circumferential direction, and are connected so as to be swingable around the rotation axis.

  On the inner side of the first locking member 41, there are a bead portion 16 formed on the outer tube 11 of the first double tube 10 and a step portion 27 formed on the outer tube 21 of the second double tube 20. A groove 44 is provided to be fitted and restrained from moving in the axial direction. The other end of the first locking member 41 in the circumferential direction is provided with a fixed piece 45 that is partly protruding in a hook shape and provided outside. The fixed piece 45 has a through hole 46 formed in a direction substantially parallel to the axis of the pipe clamp 40 and a guide groove 47 recessed at the top.

  The second locking member 42 has a groove portion 48 that holds the bead portion 16 of the first double tube 10 and the stepped portion 27 of the second double tube 20 inside thereof, and one at the other end in the circumferential direction. And two fixed pieces 49 that are externally provided so that the portion protrudes like a bowl. These fixing pieces 49 are located on both sides of the fixing piece 45 of the first locking member 41 when the first locking member 41 and the second locking member 42 are combined, and the through hole 50 is It is coaxial with the through-hole 46 formed in the fixed piece 45, and the guide groove 51 is also aligned with the guide groove 47 formed in the fixed piece 45.

  The fixing pin 43 has a thickness that can be inserted into the through holes 46 and 50 of the fixing pieces 45 and 49, and a round bar having spring property is bent into a substantially U shape, and one arm has The tip portion is formed so as to approach the other arm so as to have a function of preventing the removal.

  The pipe clamp 40 having the above-described configuration includes the bead portion 16 of the first double tube 10 and the second double tube 20 in the groove portions 44 and 48 of the first locking member 41 and the second locking member 42. By fitting the first locking member 41 and the second locking member 42 while fitting the stepped portion 27, the entire circumference of the bead portion 16 and the stepped portion 27 is restrained. As a result, the through holes 46 and 50 and the guide grooves 47 and 51 of the fixed pieces 45 and 49 are aligned, so that the fixed piece 45 is disposed by arranging the fixing pins 43 in the through holes 46 and 50 and the guide grooves 47 and 51. 49 are fixed, and the first double tube 10 and the second double tube 20 are tightly connected.

  The first double pipe 10 and the second double pipe 20 locked by the pipe clamp 40 function as an internal heat exchanger in the refrigeration cycle of the automotive air conditioner. In this case, as indicated by arrows in FIG. 3, the flow direction of the refrigerant is, for example, the inner pipe 12 of the first double pipe 10 and the second double pipe 20, the connection joint portions 14, 24 and the inner pipe 22. Constitutes a high-temperature / high-pressure refrigerant passage for supplying high-temperature / high-pressure refrigerant from the receiver dryer to the expansion valve, and the space between the outer pipes 11, 21 and the high-temperature / high-pressure refrigerant passage is from the evaporator to the compressor A low-temperature / low-pressure refrigerant passage through which a low-temperature / low-pressure refrigerant flows is formed, and the high-temperature / high-pressure refrigerant and the low-temperature / low-pressure refrigerant are heated via the inner pipes 12, 22, connection joint portions 14, 24 and struts 13, 23. Will be exchanged.

It is sectional drawing which shows the connection side edge part structure of a double pipe. It is a figure which shows the cross section of a double tube. It is sectional drawing which shows a double pipe joint structure. It is a perspective view which shows an example of a pipe clamp.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 1st double pipe 11 Outer pipe 12 Inner pipe 13 Strut 14 Connection joint part 15 Expanded part 16 Bead part 17 Sealing material mounting part 18 Sealing material installation groove 20 Second double pipe 21 Outer pipe 22 Inner pipe 23 Post 24 connection joint portion 25, 26 expanded portion 27 stepped portion 28 expanded portion 31, 32 O-ring 40 pipe clamp 41 first locking member 42 second locking member 43 fixing pin 44 groove portion 45 fixing piece 46 through hole 47 guide Groove 48 Groove 49 Fixed piece 50 Through hole 51 Guide groove

Claims (7)

In a double pipe joint structure in which a first double pipe and a second double pipe each having a coaxial inner pipe and an outer pipe are connected,
The first double pipe and the second double pipe have a cylindrical processing region in which a connecting portion of the outer pipe protrudes outward in the axial direction from the inner pipe outside the inner diameter of the outer pipe. The inner pipe connecting portions are formed in a shape that can be fitted to each other at a position of the inner pipe, and the connecting portions of the inner pipe are in the region of the connecting portion of the outer pipe and at positions outside the inner diameter of the inner pipe. 2. A double pipe joint structure characterized in that a cylindrical connection joint part having a fitting shape is coupled to the tip of the inner pipe.   The double pipe joint structure according to claim 1, wherein the connection joint portion is fitted to a distal end of the inner pipe and bonded by applying an adhesive to the fitting portion and hermetically fixing.   The double pipe joint structure according to claim 1, wherein the connection joint portion is coupled by being fitted to a tip of the inner pipe.   The first double tube and the second double tube are hollow extrusion molding in which the outer tube, the inner tube, and a column supporting these in a concentric state are integrally formed by hollow extrusion molding. The cylindrical processing region of the outer tube is formed by removing the inner tube and the support column from the end side of the hollow extruded material, and the inner joint to which the connection joint portion is coupled. The double pipe joint structure according to claim 1, wherein a tip end of the tube is formed by removing the support column from an end side of the hollow extruded material.   2. The double pipe joint structure according to claim 1, wherein each of the first double pipe and the second double pipe has a distal end of the connection joint portion protruding outward in an axial direction from an end surface of the outer pipe.   2. The double pipe joint structure according to claim 1, wherein the fitting part of the connection part of the outer pipe and the fitting part of the connection joint part are respectively sealed by a seal ring.   The said 1st double pipe and the said 2nd double pipe are locked by constraining the perimeter of the connection part of the said outer pipe | tube fitted into each other with a pipe clamp mutually. Double pipe joint structure.

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