JP2009281622A - Inner tube joint structure of internal heat exchanger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To branch an inner tube from an outer tube without using an expensive joint member such as a block, in a double tube-type internal heat exchanger used in a refrigerating cycle of an air conditioning device for an automobile. <P>SOLUTION: A metallic pipe 16 integrally provided with a cylindrical joint section 17 flared at its distal end, on its outer face, is connected to one end of the outer tube 11, a distal end part of the inner tube 12 is inserted to the cylindrical joint section 17, and a distal end of high-pressure piping 13 is throttled in a state of covering the flared part of the cylindrical joint section 17, thus the high-pressure piping 13 is connected to the cylindrical joint section 17. Here, an O-ring 18 is disposed on a part surrounded by the inner tube 12, the cylindrical joint section 17 and the high-pressure piping 13. Thus the leakage of a refrigerant from the high-pressure piping 13 into the metallic pipe 16, and the leakage of a refrigerant from the high-pressure piping 13 to the atmospheric air are simultaneously prevented. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an inner pipe joint structure of an internal heat exchanger, and in particular, between a high-temperature and high-pressure refrigerant introduced into an expansion device and a low-temperature and low-pressure refrigerant introduced into a compressor in a refrigeration cycle of an automotive air conditioner. The present invention relates to an inner pipe joint structure of an internal heat exchanger that performs heat exchange at a temperature.

  In an automotive air conditioner, a compressor, a condenser and a receiver dryer are generally installed in an engine room, an evaporator is installed in a vehicle compartment, and the compressor, condenser, receiver dryer, expansion valve and evaporator are arranged in this order. Then, the refrigerant is piped so that the refrigerant flows out, and the refrigerant exiting the evaporator returns to the compressor to constitute the refrigeration cycle. The expansion valve is installed in the partition that separates the vehicle compartment from the engine room, and serves as a joint between the piping inside the vehicle compartment and the piping inside the engine room, or in or near the evaporator. It is installed in.

  In such a refrigeration cycle, it is known to include an internal heat exchanger for the purpose of improving the coefficient of performance. This internal heat exchanger exchanges heat between the high-temperature and high-pressure refrigerant sent from the receiver dryer to the expansion valve and the low-temperature and low-pressure refrigerant sent from the evaporator to the compressor, and is introduced into the expansion valve. The degree of supercooling of the refrigerant and the degree of superheat of the refrigerant introduced into the compressor are increased, thereby improving the coefficient of performance of the refrigeration cycle.

  Since the internal heat exchanger used in the refrigeration cycle places importance on the function of the piping rather than on the heat exchange rate, a large surface area for heat exchange is not necessary. For this reason, for example, a very simple coaxial double tube type is used (for example, see Patent Document 1). This coaxial double pipe is an outer pipe, an inner pipe housed in the outer pipe, and a support disposed between the inner pipe and the outer pipe to maintain concentricity between the inner pipe and the outer pipe. And is integrally formed by hollow extrusion molding.

The double pipe type internal heat exchanger is provided with a joint member that branches the double pipe and connects two independent external pipes at the end thereof (see, for example, Patent Document 2). This joint member has a cylindrical female portion that receives the outer tube on one surface, and an insertion hole that holds the inner tube extending from the outer tube through the joint member on the opposite surface; A protrusion having an axis parallel to the axis of the inner tube at a position spaced from the insertion hole, and the hole of the protrusion is between the outer tube and the inner tube of the internal heat exchanger inside the joint member. It is the structure which is connected to the passage.
Japanese translation of PCT publication No. 2003-510546 (paragraph [0018], FIG. 8) JP 2004-239318 A (paragraphs [0032]-[0037], FIG. 6)

  However, the joint member as described above is composed of a block manufactured by die casting or cutting, but such a block has a problem that the manufacturing cost is high.

  This invention is made | formed in view of such a point, and provides the inner pipe joint structure of the internal heat exchanger which can branch an inner pipe from an outer pipe, without using a joint member like a block. With the goal.

  In order to solve the above-described problems, the present invention includes an outer tube and an inner tube accommodated in the outer tube, and is introduced into a high-temperature and high-pressure refrigerant and compressor that are introduced into the expansion device in the refrigeration cycle. In the inner pipe joint structure of the double pipe type internal heat exchanger that performs heat exchange with the low-temperature and low-pressure refrigerant to be performed, the outer surface near the tip of the outer pipe is approximately equal to the outer diameter of the inner pipe A cylindrical joint portion having an inner diameter is protruded, a tip portion of the inner pipe is inserted into the cylindrical joint portion in a fluid-tight state, and an external pipe is connected to the cylindrical joint portion in a fluid-tight state. An internal pipe joint structure for an internal heat exchanger is provided.

  According to such an inner pipe joint structure of an internal heat exchanger, the outer pipe which is a constituent element of the internal heat exchanger is processed to form a cylindrical joint portion that branches the inner pipe from the outer pipe, thereby reducing the cost. The inner pipe joint structure.

  The inner pipe joint structure of the internal heat exchanger having the above configuration is such that a cylindrical joint part is directly formed by machining an outer pipe without using a block that requires cutting with a lathe. Since the external pipe is connected through the inner pipe, there is an advantage that the inner pipe joint structure can be realized at low cost.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings, taking as an example a case where the present invention is applied to an internal heat exchanger used in a refrigeration cycle of an automotive air conditioner.
FIG. 1 is a system diagram showing a refrigeration cycle of an automotive air conditioner.

  The refrigeration cycle of this automotive air conditioner includes a compressor 1 that compresses a refrigerant, a condenser 2 that condenses the compressed refrigerant by heat exchange with outside air, and separates the condensed refrigerant into gas and liquid and a refrigeration cycle. A receiver dryer 3 for storing the excess refrigerant is provided in the engine room. The refrigeration cycle includes an internal heat exchanger 4 that performs piping between the engine room and the vehicle compartment, and is further expanded with a temperature type expansion valve 5 that squeezes and expands the liquid refrigerant from the internal heat exchanger 4. An evaporator 6 that evaporates the refrigerant by heat exchange with the air in the passenger compartment is provided in the passenger compartment. The evaporator 6 is connected to the expansion valve 5 in order to detect the temperature and pressure of the refrigerant that has left the evaporator 6, and is further connected to the suction port of the compressor 1 via the internal heat exchanger 4.

  The internal heat exchanger 4 has a high-pressure passage for sending high-temperature and high-pressure liquid refrigerant from the receiver dryer 3 to the expansion valve 5 and a low-pressure passage for sending low-temperature and low-pressure gas refrigerant from the evaporator 6 to the compressor 1. Heat exchange is performed between the high-temperature refrigerant flowing through the high-pressure passage and the low-temperature refrigerant flowing through the low-pressure passage. Thereby, the refrigerant flowing through the high-pressure passage is supercooled by the refrigerant in the low-pressure passage, and the refrigerant flowing through the low-pressure passage is overheated by the refrigerant in the high-pressure passage, so that the coefficient of performance of the refrigeration cycle can be improved. .

  In this internal heat exchanger 4, the end of the expansion valve 5 side has an expansion valve 5 having a double pipe connection structure and can be connected to the expansion valve 5 with a double pipe structure. The structure that branches the inner tube from the outer tube is not necessary. Therefore, in this example of the refrigeration cycle, the internal heat exchanger 4 has an inner pipe joint structure at the end on the side where the compressor 1 and the receiver dryer 3 are connected.

FIG. 2 is a sectional view showing the inner pipe joint structure according to the first embodiment of the internal heat exchanger.
The internal heat exchanger 10 has an outer pipe 11 and an inner pipe 12 accommodated in the outer pipe 11, and the inner pipe 12 and the outer pipe 11 are used as a high-pressure pipe and a low-pressure pipe of a refrigeration cycle, respectively. This double pipe heat exchanger is also used as a pipe. In particular, the internal heat exchanger 10 is used for piping in an engine room, and the left end portion in the figure is a double pipe structure installed in a vehicle compartment by a partition wall that is a boundary between the vehicle compartment and the engine room. Connected to the internal heat exchanger. Therefore, the illustrated internal heat exchanger 10 constitutes a part of the internal heat exchanger 4 of FIG. The internal heat exchanger 10 has an inner pipe joint structure on the right side of the drawing, and the inner pipe 12 is connected to a high-pressure pipe 13 on the outlet side of the receiver dryer 3 (corresponding to the external pipe of claim 1). The outer tube 11 is connected to the compressor 1 via the flexible hose 14.

  The outer tube 11 is a straight pipe, and the inner tube 12 accommodated therein is processed into a shape in which portions excluding the vicinity of both ends are spirally wound. The spiral portion of the inner tube 12 is wound at a very long helical pitch, and is formed so that the diameter of the virtual cylinder inscribed in the outermost periphery is slightly larger than the inner diameter of the outer tube 11. Therefore, when the inner tube 12 is press-fitted into the outer tube 11, the entire circumference of the spiral portion is accommodated in the outer tube 11 with the inner wall of the outer tube 11 in contact with the inner tube 12. As a result, the inner tube 12 is tightly constrained therein by the outer tube 11, so that even if vibration is applied from the outside, no abnormal noise is generated due to collision with the outer tube 11. .

  Further, since the spiral portion of the inner tube 12 is wound at a loose helical pitch, the overall length does not become long, so there is no pressure loss due to the long refrigerant passage, and the outer tube 11 is in the longitudinal direction. There is no portion physically coupled along the outer tube 11, and the outer tube 11 and the inner tube 12 therein are very easy to bend. The bending of the heat exchanger 10 can be easily performed.

  The inner pipe 12 is provided with a positioning member 15 at an end on the vehicle interior side. The positioning member 15 includes a cylindrical portion that is fitted to a straight portion near the tip of the inner tube 12 and, for example, three support members that protrude from the outer periphery thereof. As a result, the inner tube 12 is positioned at the axial center of the outer tube 11, and the open end thereof has a coaxial double tube structure.

  A metal pipe 16 is connected to the outer tube 11 on the opposite side of the open end of the coaxial double tube structure. The metal pipe 16 has a cylindrical joint portion 17 protruding from the outer surface thereof. The cylindrical joint portion 17 can be formed relatively easily by, for example, pressing from the inside of the metal pipe 16. The cylindrical joint portion 17 has an inner diameter that is substantially equal to the outer diameter of the inner tube 12, and the tip is flared into a trumpet shape.

  The inner pipe 12 has a tip portion bent at a substantially right angle inserted through the cylindrical joint portion 17 so that the tip protrudes beyond the tip of the cylindrical joint portion 17. The high-pressure pipe 13 has an inner diameter substantially equal to the outer diameter of the inner pipe 12 and is joined to the flare portion of the cylindrical joint portion 17 by plastically deforming the flared tip. An O-ring 18 (corresponding to the seal ring of claim 1) is arranged in a space formed by the outer peripheral surface of the inner pipe 12, the flare part of the cylindrical joint part 17, and the flare part of the high-pressure pipe 13, and the high-pressure pipe 13. The high-pressure refrigerant is prevented from leaking into the low-pressure passage in the outer tube 11 or leaking into the atmosphere.

  The opening of the metal pipe 16 is reduced in diameter, and a joint member 19 is fitted in the reduced diameter portion. The joint member 19 has a through hole and a screw hole that are fixed by inserting and deforming the metal pipe 16. A flexible hose 14 having flexibility, which is attached to block vibration of the compressor 1, is terminated so that one end thereof can be connected to the metal pipe 16. That is, the flexible hose 14 has a metal pipe 20 inserted into one end thereof, a metal sleeve 21 is fitted outside the insertion region of the metal pipe 20, and the metal sleeve 20 is caulked to fix the metal pipe 20 in an airtight manner. Has been. A joint member 22 is brazed to the open end of the metal sleeve 21. The joint member 22 is integrally formed with a cylindrical projection that fits into the metal pipe 16 in the joint member 19, and a groove is provided around the cylindrical projection to fit an O-ring 23. The joint member 22 is connected to the outer pipe 11, the metal pipe 16, the metal pipe 20, and the flexible hose 14 by fitting the cylindrical projecting portion to the metal pipe 16 in the joint member 19 and fastening with the bolt 24. The

FIG. 3 is an explanatory view showing an assembly procedure of the inner pipe joint structure, where (A) shows the first stage, (B) shows the second stage, and (C) shows the third stage. .
As shown in FIG. 3A, the inner pipe joint structure of the inner heat exchanger 10 is first bent at a right angle at the tip of the inner pipe 12 protruding from the outer pipe 11, and then the outer pipe. The outer pipe 11 and the metal pipe 16 are coupled by inserting the metal pipe 16 into the expanded portion at the open end of the eleventh and drawing the tip of the outer pipe 11.

  Next, as shown in FIG. 3B, the distal end portion of the inner tube 12 is inserted into a cylindrical joint portion 17 formed on the metal pipe 16. At this time, even if an adhesive is poured between the distal end portion of the inner tube 12 and the cylindrical joint portion 17 so that the distal end portion of the inner tube 12 does not come out of the cylindrical joint portion 17 and return into the metal pipe 16. Good. In this case, the adhesive can fix the inner tube 12 and the cylindrical joint portion 17 and fill a clearance between the inner tube 12 and the cylindrical joint portion 17 to be in a fluid-tight state. Then, an O-ring 18 is fitted to the distal end portion of the inner pipe 12, and the distal end of the flared high-pressure pipe 13 is put on the distal end of the cylindrical joint portion 17.

  Finally, as shown in FIG. 3C, the tip of the high-pressure pipe 13 is squeezed so as to follow the flare back surface 17a with the tip of the high-pressure pipe 13 covering the flare back surface 17a of the cylindrical joint portion 17. By processing, the cylindrical joint portion 17 and the high-pressure pipe 13 are coupled in a fluid-tight state. By drawing the high-pressure pipe 13, the O-ring 18 is deformed into a substantially triangular cross-sectional shape by the outer peripheral surface of the tip portion of the inner pipe 12, the flare inner surface 17 b of the cylindrical joint portion 17, and the flare inner surface 13 a of the high-pressure pipe 13. The refrigerant leakage from the high-pressure pipe 13 into the metal pipe 16 and the refrigerant leakage from the high-pressure pipe 13 to the atmosphere are prevented at the same time.

  FIG. 4 is a cross-sectional view of an essential part showing an inner pipe joint structure according to a second embodiment of the internal heat exchanger. In FIG. 4, the same components as those shown in FIG. 2 are denoted by the same reference numerals, and detailed description thereof is omitted.

  According to the inner pipe joint structure of the internal heat exchanger 10, the tip portion of the inner pipe 12 is prevented from coming out of the high pressure pipe 13 and further from the cylindrical joint portion 17 due to axial stress caused by vibration and high pressure. ing. That is, the distal end portion of the inner tube 12 is expanded after being inserted into the cylindrical joint portion 17 so that the outer diameter of the expanded portion 12 a is larger than the inner diameter of the cylindrical joint portion 17. At this time, when a pipe having the same size as that shown in FIG. 2 is used as the high-pressure pipe 13, the expanded portion 12 a of the inner pipe 12 cannot be inserted into the high-pressure pipe 13. A tube expansion portion 13b is provided at a portion corresponding to 12 tube expansion portions 12a.

  In the above embodiment, the joint structure that enables the inner pipe to branch from the outer pipe at one end of the internal heat exchanger has been described in detail. It may be applied to both ends of the exchanger. The tubular joint portion 17 is formed by using a metal pipe 16 having a thickness greater than that of the outer tube 11 and processing the metal pipe 16. However, the tubular joint portion 17 is sufficient to form the tubular joint portion 17. If it has thickness, the metal pipe 16 is unnecessary and the cylindrical joint part 17 can be directly formed in the outer tube 11.

It is a system diagram which shows the refrigerating cycle of the air conditioner for motor vehicles. It is sectional drawing which shows the inner pipe joint structure which concerns on 1st Embodiment of an internal heat exchanger. It is explanatory drawing which shows the assembly procedure of an inner pipe joint structure, Comprising: (A) shows the 1st step, (B) shows the 2nd step, (C) has shown the 3rd step. It is principal part sectional drawing which shows the inner pipe joint structure which concerns on 2nd Embodiment of an internal heat exchanger.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Compressor 2 Condenser 3 Receiver dryer 4 Internal heat exchanger 5 Expansion valve 6 Evaporator 10 Internal heat exchanger 11 Outer pipe 12 Inner pipe 12a Expanded pipe part 13 High pressure piping 13a Flare inner surface 13b Expanded pipe part 14 Flexible hose 15 Positioning member 16 Metal pipe 17 Tubular joint 17a Flare back surface 17b Flare inner surface 18 O-ring 19 Joint member 20 Metal pipe 21 Metal sleeve 22 Joint member 23 O-ring 24 Bolt

Claims (7)

An outer pipe and an inner pipe housed in the outer pipe are provided, and heat is generated between the high-temperature and high-pressure refrigerant introduced into the expansion device in the refrigeration cycle and the low-temperature and low-pressure refrigerant introduced into the compressor. In the inner pipe joint structure of the double pipe type internal heat exchanger that performs exchange,
A cylindrical joint portion having an inner diameter substantially equal to the outer diameter of the inner tube is protruded from the outer surface near the distal end of the outer tube, and the distal end portion of the inner tube is inserted into the tubular joint portion in a fluid-tight state. An internal pipe joint structure for an internal heat exchanger, wherein an external pipe is connected to the cylindrical joint portion in a fluid-tight state.   Each of the cylindrical joint portion and the external pipe has a flared tip, and the tip of the external pipe is narrowed so as to follow the flare back surface while covering the flare back surface of the tip of the cylindrical joint portion. The internal pipe joint structure of an internal heat exchanger according to claim 1, wherein the cylindrical joint portion and the external pipe are connected by processing.   A seal ring is disposed in a space surrounded by the outer peripheral surface of the distal end portion of the inner pipe, the flare inner surface of the cylindrical joint portion, and the flare inner surface of the outer pipe, and the inner pipe, the cylindrical joint portion, and the outer pipe The inner pipe joint structure of the internal heat exchanger according to claim 2, wherein the space is in a fluid-tight state.   The inner pipe joint structure of an internal heat exchanger according to claim 1, wherein the inner pipe and the cylindrical joint portion are fixed to each other and fluid-tight with an adhesive.   The inner pipe joint structure for an internal heat exchanger according to claim 1, wherein the outer pipe has an inner diameter substantially equal to an outer diameter of the inner pipe.   The internal heat exchanger according to claim 5, wherein a tip portion of the inner pipe is expanded after being inserted into the cylindrical joint portion, and a portion corresponding to the expanded portion of the inner pipe is expanded. Inner pipe joint structure.   The inner pipe joint structure for an internal heat exchanger according to claim 1, wherein the outer pipe is formed by processing a pipe of a separate part at a portion where the cylindrical joint portion is formed.

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