JP2011102596A - Pipe joint structure, and heat exchanger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To secure pressure capacity of a pipe joint through which carbon dioxide or the like with high coolant pressure passes; and further to meet weight saving or space saving of a pipe. <P>SOLUTION: In a pipe joint structure where a first pipe (main pipe 1) is connected with a second pipe (branch pipe 2) in a branched way. An outer diameter of the joint 5 of the first pipe is formed so that the outer diameter of the joint 5 is smaller than that of parts other than the joint. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a pipe joint structure used in a refrigeration cycle apparatus and the like, and more particularly, to a heat exchanger using a high-pressure refrigerant such as carbon dioxide and requiring high pressure resistance.

When carbon dioxide is used as a refrigerant in a heat exchanger such as a refrigeration cycle apparatus, the refrigerant pressure inside the pipe is significantly higher than that of conventional chlorofluorocarbons. For this reason, the part which may become a problem on structure, such as a pipe joint part, needs a design of especially high pressure | voltage resistance from a viewpoint of pressure | voltage resistance. Therefore, as a pipe joint structure that can withstand such a high internal pressure, for example, in Patent Document 1, in order to suppress the deformation due to the internal pressure load of the main pipe in the joint portion, on the center line of the main pipe orthogonal to the main pipe, A pipe joint structure has been proposed in which reinforcing ribs formed in a semicircular arc ring shape are welded to at least a semicircular arc portion on the outer periphery.
Further, Patent Document 2 proposes a pipe joint structure in which the outer wall is deformed in a direction in which the distance from the portion where the header pipe stress is concentrated is shortened at the portion where the tube insertion hole of the header pipe is provided.

Japanese Utility Model Publication No. 62-7913 (FIGS. 5 and 6) JP 2001-59687 A (FIG. 2)

The pipe joint structure in which the reinforcing ribs are welded as in Patent Document 1 has a structure excellent in pressure resistance, but when the deformation amount of the main pipe is very large, the reinforcing ribs welded to the main pipe are damaged or peeled off. There is a concern that
In order to avoid such a situation, it is conceivable to increase the thickness of the reinforcing rib sufficiently, but this increases the weight of the main pipe and further the weight of the refrigeration cycle device such as a heat exchanger, thereby reducing the weight. It will be against the request. In addition, if the thickness of the main pipe is increased, the main pipe becomes larger, which is contrary to the demand for space saving.

  Moreover, in the pipe joint structure disclosed in Patent Document 2, the outer wall of the header pipe is deformed to form a cross section of the medium passage in a semicircular arc shape. Not enough to be able to withstand. In addition, the connection structure or connection tool between the header pipe and the refrigerant pipe becomes special, which increases the cost.

  The present invention, in view of the problems of the prior art as described above, ensures the pressure-resistant strength of the pipe joint portion through which carbon dioxide or the like having a high refrigerant pressure passes, and further satisfies the weight reduction and space saving of the pipe. Is an issue.

  The pipe joint structure according to the present invention is a pipe joint structure in which a second pipe is connected in a branched manner to a first pipe, and the outer diameter of the joint portion of the first pipe is the first pipe. It is formed so that it may become smaller than the outer diameter dimension of parts other than this joint part.

  According to the present invention, there is a pipe joint structure that is used in a refrigeration cycle apparatus or the like, in particular, uses carbon dioxide or the like as a refrigerant and requires pressure resistance, and the outer diameter of the joint portion of the first pipe is Since it is formed so as to be smaller than the outer diameter of the portion other than the joint portion, the shape in the longitudinal direction of the first tube brings about an effect of improving rigidity, and further, the deformation amount of the joint portion of the first tube is reduced. Since the pressure can be reduced, the pressure (strength) that pushes the connection port with the second pipe (opening force), that is, the stress itself is reduced, so that the pressure strength can be improved.

It is a perspective view which shows the pipe joint structure which concerns on Embodiment 1 of this invention. 2 is a schematic side view of a main pipe according to Embodiment 1. FIG. It is sectional drawing (enlarged sectional drawing cut | disconnected by AA of FIG. 2) of the coupling part of the main pipe by Embodiment 1. FIG. It is sectional drawing (enlarged sectional drawing cut | disconnected by BB of FIG. 2) of parts other than the joint part of the main pipe by Embodiment 1. FIG. It is sectional drawing (enlarged sectional drawing cut | disconnected by AA of FIG. 2) of the coupling part of the main pipe by Embodiment 2. FIG. It is sectional drawing (enlarged sectional drawing cut | disconnected by AA of FIG. 2) of the coupling part of the main pipe by Embodiment 3. FIG. FIG. 10 is a schematic side view of a main pipe according to a fourth embodiment. It is a perspective view which shows the structure of the heat exchanger which concerns on Embodiment 5. FIG. It is sectional drawing of the heat exchanger which concerns on Embodiment 5. FIG. It is sectional drawing of the heat exchanger which concerns on Embodiment 5. FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

Embodiment 1 FIG.
FIG. 1 is a perspective view showing a pipe joint structure according to Embodiment 1 of the present invention, and FIG. 2 is a view of the main pipe 1 shown in FIG. 3 is an enlarged cross-sectional view showing a cross section of the joint portion of the main pipe 1 shown in FIG. 2 cut along AA, and FIG. 4 is a cross section of the main pipe 1 other than the joint portion taken along BB. It is an expanded sectional view which expands and shows the cut section. In the following description, the first pipe is described as a “main pipe” and the second pipe is described as a “branch pipe”. Moreover, in each figure, what attached | subjected the same code | symbol shows the same or equivalent thing.

  A main pipe 1 having a refrigerant passage 4 through which a high-pressure refrigerant such as carbon dioxide circulates is provided with a hole of an insertion hole 3 (connection port) on the outer peripheral surface. 2 is inserted. The main pipe 1 and the branch pipe 2 inserted into the insertion hole 3 are joined by brazing or welding. 1 shows the structure of a pipe joint in which the branch pipe 2 is inserted into the insertion hole 3 of the main pipe 1 shown in FIG. 2, and each pipe of the main pipe 1 and the branch pipe 2 is made of a material having good heat conductivity. For example, it is made of aluminum alloy, copper, or stainless steel.

  The shape of the insertion hole 3 is not limited to a flat shape or a long hole shape as shown, but may be a circle or the like. The shape matches the outer shape of the connection end of the branch pipe 2. Further, the insertion direction (connection direction) of the branch pipe 2 with respect to the main pipe 1 is not limited to the orthogonal direction, and the branch pipe 2 can be connected at an arbitrary angle other than a right angle with respect to the pipe axis of the main pipe 1.

In the present embodiment, the outer diameter dimension d ₁ of the main pipe 1 in the joint portion 5 shown in FIG. 3 is smaller than the outer diameter dimension d ₂ of the main pipe 1 in the portion other than the joint portion 5 shown in FIG. d ₁ <d ₂ ), and the outer cross section of the joint portion 5 of the main pipe 1 is processed to be circular. That is, the joint portion 5 is provided with an annular recess 6, and a part thereof is cut out (opened) by the insertion hole 3 and has a circular shape (C shape). By providing the annular recess 6 on the outer periphery of the main pipe 1, the joint portion 5 of the main pipe 1 has a circular shape in which the outer diameter of the cross section is smaller than the cross section diameter of the portion other than the joint portion. Although a plurality of annular recesses 6 can be provided, even one can sufficiently exhibit the rigidity improvement effect. Further, in order to suppress the deformation amount of the center portion of the insertion hole 3, the annular recess 6 is preferably provided so as to substantially coincide with the center portion of the insertion hole 3.
In addition, since the joint portion 5 of the main pipe 1 is formed with a curved surface, the processed portion and other portions do not form a location that causes a structural problem such as a stress concentration portion, and the structure can ensure the pressure strength. It has become.

  In the above configuration, the refrigerant pressure acts evenly on the inner surface of the main pipe 1 by the high-pressure refrigerant passing through the refrigerant passage 4 of the main pipe 1. At this time, a force (referred to as opening force) that pushes and expands the branch pipe insertion hole 3 acts. However, by processing the outer diameter of the joint portion 5 of the main pipe 1 to be small as shown in FIG. In the joint portion 5 of 1, the shape of the main pipe 1 in the longitudinal direction brings about an effect of improving rigidity, and the deformation amount of the joint portion 5 of the main pipe 1 is reduced as compared with the conventional pipe joint structure in which the annular recess is not formed. Therefore, the force (opening force) for expanding the insertion hole 3, that is, the stress itself can be reduced. For this reason, the strength of the main pipe is relatively increased as compared with the conventional main pipe in which the outer diameter of the joint portion of the main pipe 1 is not deformed, and the structure of the joint portion having higher durability than the conventional one is possible.

Furthermore, since the outer diameter of the joint portion of the main pipe 1 can be reduced, space can be saved and an extra reinforcing member is not attached, so that there is no inconvenience that the weight of the main pipe 1 increases. Furthermore, since the outer diameter of only the joint portion of the main pipe 1 is reduced, post-processing can be performed in the design, leading to an improvement in design flexibility, and an improvement in workability can be expected.
Further, since the end portion of the main pipe 1 has a circular cross section, connection to the refrigerant pipe can be easily and reliably performed at low cost using a conventional connector.

Embodiment 2. FIG.
FIG. 5 shows the second embodiment of the present invention and is an AA enlarged sectional view of the joint portion 5 of the main pipe 1 shown in FIG. In this example, the outer cross section of the joint portion 5 of the main pipe 1 is a reduced quadrangle. In this case, when the outer wall is processed in the direction of decreasing the outer diameter, the outer wall can be formed into a quadrangle by pressing with a flat plate punch or the like. Therefore, it is easy to process the above shape and the workability is good. In addition, the outer diameter dimension here shows the length of a square side.
Even with such a configuration of the joint portion 5 of the main pipe 1, the shape in the longitudinal direction of the main pipe 1 can exhibit the effect of improving the rigidity, and therefore, substantially the same effect as in the first embodiment can be obtained.

Embodiment 3 FIG.
FIG. 6 shows the third embodiment of the present invention and is an AA enlarged cross-sectional view of the joint portion 5 of the main pipe 1 shown in FIG. In this example, the insertion hole 3 is formed by processing the inner diameter dimension d ₃ in the branch pipe insertion direction of the joint portion 5 of the main pipe 1 to be smaller than the inner diameter dimension d _{4 in the} direction orthogonal thereto (d ₃ <d ₄ ). It is possible to further reduce the stress in the direction perpendicular to the branch pipe insertion direction, and to provide a joint reinforcement structure that can secure further pressure resistance.

Here, the above-mentioned branch pipe insertion direction refers to a case where the branch pipe 2 is orthogonal to the main pipe 1. When the branch pipe 2 is connected at an angle other than 90 degrees, the pipe of the main pipe 1 passes through the center of the insertion hole 3. The purpose is that the inner diameter dimension d ₃ in the direction perpendicular to the axis is made smaller than the inner diameter dimension d ₄ in the direction orthogonal to this (that is, the pipe axis direction of the main pipe 1).

The outer diameter dimension d ₁ of the cross-sectional shape of the joint portion 5 of the main pipe 1 is formed to be smaller than the outer diameter dimension d ₂ of the portion other than the joint portion of the main pipe 1 as in the first embodiment. Yes. Therefore, in this example, the cross-sectional shape of the joint portion 5 of the main pipe 1 is formed in an elliptical shape in which the inner diameter of the minor axis is d ₃ , the inner diameter of the major axis is d ₄ , and the outer diameter is d ₁ .

Embodiment 4 FIG.
FIG. 7 is a schematic side view of the main pipe 1 showing Embodiment 4 of the present invention. Here, in the joint portion 5 of the main pipe 1, an annular recess 6 having a diameter reduced in an inclined manner along the refrigerant flow direction is provided on the outer peripheral portion of the main pipe 1. The pressure loss can be reduced by processing the inner diameter dimension reduction rate of the main pipe 1 at the center portion of the insertion hole 3 so that the downstream portion becomes larger than the upstream portion through which the refrigerant flows.
In addition, it is calculated | required by the internal-diameter dimension reduction | decrease rate of the main pipe 1 = [1- (inside diameter after processing) / (inside diameter before processing)] × 100 (%).

Embodiment 5 FIG.
8-10 is a figure which shows the structure of the heat exchanger 8 which concerns on Embodiment 5 of this invention, FIG. 8 is a perspective view of the heat exchanger 8, FIG.9 and FIG.10 is the heat exchanger 8. FIG. It is sectional drawing. In the present embodiment, the first pipe will be described as “first main pipe 11 and second main pipe 21”, and the second pipe will be described as “first branch pipe 12 and second branch pipe 22”.
As shown in FIG. 9, the heat exchanger 8 has a flat first branch pipe 12 having a first refrigerant flow path through which the first refrigerant flows, and a substantially rectangular second refrigerant flow path through which the second refrigerant flows. It has a flat second branch pipe 22, a tubular first main pipe 11 connected to both ends of the first branch pipe 12, and a tubular second main pipe 21 connected to both ends of the second branch pipe. In addition, the 1st branch pipe 12 and the 2nd branch pipe 22 are comprised, for example by 6 rows of branch pipes, as shown in FIG. 10 which is sectional drawing which shows the structure of the heat exchanger 8. As shown in FIG.
Each tube constituting the heat exchanger 8 is made of a material having good thermal conductivity, for example, aluminum alloy, copper and stainless steel, and is manufactured by extrusion molding or pultrusion molding. As shown in FIG. 10, the insertion holes 3 into which the end portions of the first branch pipe 11 or the second branch pipe 21 are respectively inserted are provided on the circumferential side surfaces of the first main pipe 11 and the second main pipe 21. The joints 10 and 20 connecting the first branch pipe 12 and the first main pipe 11 and the second branch pipe 22 and the second main pipe 21 are brazed using a brazing material such as an aluminum-silicon system. The

The first main pipe 11 and the second main pipe 21 are connected to a refrigerant circuit of a cooling system such as a heat pump device in which the heat exchanger 8 is mounted, and a first refrigerant flowing through the first branch pipe 12 and a second branch pipe 22 are connected to the first main pipe 11 and the second main pipe 21. Heat exchange is performed with the flowing second refrigerant.
Here, the annular recess 6 is formed so that the outer diameter dimension of the joint portion of the first main pipe 11 and the second main pipe 21 is smaller than the outer diameter dimension of the portion other than the joint portion of the first main pipe 11 and the second main pipe 21. The shape of the first main pipe 11 and the second main pipe 21 in the longitudinal direction brings about an effect of improving rigidity, and compared with a conventional pipe joint structure in which an annular recess is not formed. Therefore, the force for expanding the insertion hole 3 (opening force F indicated by an arrow in FIG. 9), that is, the stress itself is reduced, and the pressure resistance of the pipe joint and the heat exchanger 8 is reduced. The strength against pressure can be improved by increasing the strength relative to the conventional one.

  Moreover, since the outer diameter of the joint part of the 1st main pipe 11 and the 2nd main pipe 21 can be made small, while being able to attain space saving and attaching an extra reinforcement member, the 1st main pipe 11 is not attached. And the inconvenience that the weight of the 2nd main pipe 21, and also the heat exchanger 8 increases is also eliminated. Furthermore, since the outer diameters of only the joint portions of the first main pipe 11 and the second main pipe 21 are reduced, post-processing can be performed in the design, leading to improvement in design flexibility in the heat exchanger 8, and improvement in workability is also expected. it can.

  Note that high-pressure refrigerant such as carbon dioxide is used for the first refrigerant and the second refrigerant. For example, a high-pressure refrigerant is used for the first refrigerant, and a low-pressure refrigerant having a lower pressure than the first refrigerant is used for the second refrigerant. In this case, the annular recess 6 may be provided only in the first main pipe 11, and the annular recess may not be provided in the second main pipe 21.

  DESCRIPTION OF SYMBOLS 1 Main pipe (1st pipe), 2 branch pipe (2nd pipe), 3 Insertion hole (connection port), 4 Refrigerant passage, 5 Joint part, 6 Annular recessed part, 8 Heat exchanger, 10 1st main pipe and 1st Junction part of 1 branch pipe, 11 1st main pipe, 12 1st branch pipe, 20 Junction part of 2nd main pipe and 2nd branch pipe, 21 2nd main pipe, 22 2nd branch pipe.

Claims (7)

A pipe joint structure for connecting the second pipe to the first pipe in a branched shape,
A pipe joint structure, wherein an outer diameter dimension of a joint portion of the first pipe is formed to be smaller than an outer diameter dimension of a portion other than the joint portion of the first pipe.   The pipe joint structure according to claim 1, wherein a cross section of the joint portion of the first pipe is formed in a reduced circular shape.   2. The pipe joint structure according to claim 1, wherein a cross section of the joint portion of the first pipe is formed into a reduced quadrangle.   In the joint portion of the first tube, the inner diameter dimension in a direction perpendicular to the tube axis of the first tube passing through the center portion of the connection port with the second tube is the tube axis direction of the first tube. The pipe joint structure according to any one of claims 1 to 3, wherein the pipe joint structure is formed to be smaller than an inner diameter dimension of the pipe joint.   The pipe joint structure according to any one of claims 1 to 4, wherein the joint portion of the first pipe is formed of a curved surface.   An annular recess having a diameter reduced in an inclined manner along the flow direction of the refrigerant is provided on the outer periphery of the first tube, and the inner diameter of the first tube is reduced at the center of the connection port with the second tube. The pipe joint structure according to any one of claims 1 to 5, wherein the downstream portion is larger in rate than the upstream portion through which the refrigerant flows.   A heat exchanger using the pipe joint structure according to any one of claims 1 to 6.

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