Patent Description:
An air conditioner configured to execute refrigeration cycle operation includes a refrigerant circuit having pressure vessels such as a compressor, an accumulator, and a receiver, and a refrigerant pipe connected to each of the pressure vessels. Patent Literature <NUM> discloses adopting a refrigerant pipe made of less expensive stainless steel in place of a refrigerant pipe made of copper exerting excellent processability such as bending and excellent heat conductivity.

The pressure vessels provided on the refrigerant circuit each include a vessel body, an inlet pipe causing a refrigerant to flow into the vessel body, and an outlet pipe causing the refrigerant to flow out of the vessel body. Typically, the vessel body is made of iron whereas the inlet pipe and the outlet pipe are made of copper. Similarly to the refrigerant pipe according to <CIT>, the inlet pipe and the outlet pipe may be made of stainless steel in consideration of cost or the like.

However, the inlet pipe and the outlet pipe made of stainless steel may not be able to be connected with the vessel body made of iron in a manner similar to a conventional method. A pressure vessel and a refrigeration apparatus are also known from <CIT> that describes a vapor-liquid separator input and output structure which comprises a tank, an upper end cover, a stainless steel input pipe and a stainless steel output pipe, wherein the upper end cover covers the end part of the tank and is provided with an inlet, an outlet and flanging parts at the inlet and the outlet, the stainless steel input pipe penetrates through the inlet, the stainless steel output pipe penetrates through the outlet, the outer end of the stainless steel input pipe and the outer end of the stainless steel output pipe are respectively provided with a flaring part, a copper insertion pipe is inserted into each flaring part, and the bottom end of each copper insertion pipe, each flaring part and each flanging part are fixed in a welding manner for forming a five-layer structure consisting of a copper insertion pipe, a first flux layer, a flaring part, a second flux layer and an upper end cover flanging part from inside to outside. Moreover, a pressure vessel and a refrigeration apparatus are also known from <CIT>, and <CIT>.

It is an object of the present invention to provide a pressure vessel and a refrigeration apparatus, which allow connection, in a manner similar to the conventional method, between a vessel body and inlet and outlet pipes at least one of which is made of stainless steel.

According to the above configuration, the inlet pipe and/or the outlet pipe includes the first portion made of stainless steel and the second portion made of a material whose main component is copper, and the second portion is connected to the vessel body. The second portion can thus be connected to the vessel body in a manner similar to a conventional technique for an inlet pipe and/or an outlet pipe made of copper.

(<NUM>) Preferably, the first portion has an outer circumferential surface connected with an inner circumferential surface of the second portion, and
the second portion has an end surface on the second side in the pipe axial direction, the end surface being disposed flush with an end surface on the second side in the pipe axial direction of the first portion, or projecting toward the second side in the pipe axial direction than the end surface of the first portion.

According to this configuration, the first portion does not project toward the second side in the pipe axial direction than the second portion, for reduction in entire size of the inlet pipe and/or the outlet pipe.

(<NUM>) Preferably, a different second pipe is connected to an end on the second side in the pipe axial direction of the second portion.

(<NUM>) Preferably, the vessel body includes a joint tube made of iron, and the second portion is connected to the joint tube.

(<NUM>) Preferably, the second portion is connected to an end on the first side in the pipe axial direction of the joint tube, and
a different third pipe is connected to an end on the second side in the pipe axial direction of the j oint tube.

According to such a configuration, the inlet pipe and/or the outlet pipe and the third pipe disposed in the vessel body can be connected to each other via the joint tube.

(<NUM>) Preferably, the end surface on the second side in the pipe axial direction of the second portion projects toward the second side in the pipe axial direction than the end surface on the second side in the pipe axial direction of the first portion.

According to this configuration, the second portion and the third pipe connected via the joint tube are less likely to form any gap therebetween, inhibiting entry or the like of the refrigerant into the gap.

(<NUM>) Preferably, the second portion has a portion extending into the vessel body.

According to such a configuration, the inner pipe disposed in the vessel body can be constituted by the second portion thus extended, achieving reduction in the number of components of the pipe.

(<NUM>) Preferably, the end on the second side in the pipe axial direction of the first portion is provided with a minor diameter portion reduced in outer diameter, and
the minor diameter portion has an outer circumferential surface connected to the inner circumferential surface of the second portion.

According to such a configuration, the minor diameter portion of the first portion is inserted to the second portion and the end of the second portion is made in contact with a portion around a proximal end of the minor diameter portion, for positioning in the pipe axial direction of the first portion and the second portion.

(<NUM>) Preferably, the first portion has a portion overlapped with the vessel body in a pipe diameter direction.

According to this configuration, the first portion stronger than the second portion is overlapped with the vessel body in the pipe diameter direction, for improvement in connection strength between the vessel body and the inlet pipe and/or the outlet pipe.

(<NUM>) Preferably, the end on the first side in the pipe axial direction of the first portion is provided with a plated portion made of a material whose main component is copper or a tube made of a material whose main component is copper.

According to this configuration, a refrigerant pipe made of copper can be connected easily to the end of the first portion made of stainless steel, with use of an inexpensive brazing material.

(<NUM>) The present invention provides a refrigeration apparatus including the pressure vessel according to any one of (<NUM>) to (<NUM>) described above.

Embodiments of the present invention will be described in detail hereinafter with reference to the accompanying drawings.

Description will be made hereinafter to embodiments of the present invention with reference to the drawings.

<FIG> is a schematic configuration diagram of a refrigeration apparatus including a pressure vessel according to the first embodiment of the present invention.

A refrigeration apparatus <NUM> exemplifies an air conditioner configured to condition indoor temperature and indoor humidity, and includes an outdoor unit <NUM> disposed outdoors and an indoor unit <NUM> disposed indoors. The outdoor unit <NUM> and the indoor unit <NUM> are connected to each other via a refrigerant pipe <NUM>.

The refrigeration apparatus <NUM> includes a refrigerant circuit <NUM> configured to execute vapor compression refrigeration cycle operation. The refrigerant circuit <NUM> includes a plurality of element components and the refrigerant pipe <NUM> connecting the plurality of element components. The refrigerant circuit <NUM> includes, as the element components, an indoor heat exchanger <NUM>, a compressor <NUM>, a muffler <NUM>, an outdoor heat exchanger <NUM>, an expansion mechanism <NUM>, an accumulator <NUM>, a four-way switching valve (switching mechanism) <NUM>, and the like, which are connected via the refrigerant pipe <NUM>. The refrigerant pipe <NUM> includes a liquid pipe <NUM> and a gas pipe <NUM>. The liquid pipe <NUM> and the gas pipe <NUM> are provided with a liquid shutoff valve <NUM> and a gas shutoff valve <NUM>, respectively.

The indoor heat exchanger <NUM> is provided in the indoor unit <NUM> and executes heat exchange between a refrigerant and indoor air. Examples of the indoor heat exchanger <NUM> include a fin-and-tube heat exchanger of a cross-fin type and a heat exchanger of a microchannel type. The indoor heat exchanger <NUM> is provided therearound with an indoor fan (not depicted) configured to send indoor air to the indoor heat exchanger <NUM> and send conditioned air to indoors.

The compressor <NUM>, the muffler <NUM>, the outdoor heat exchanger <NUM>, the expansion mechanism <NUM>, the accumulator <NUM>, and the four-way switching valve <NUM> are provided in the outdoor unit <NUM>. The compressor <NUM> is configured to compress a refrigerant sucked from an inlet pipe and discharge the compressed refrigerant from an outlet pipe. Examples of the compressor <NUM> include various compressors such as a scroll compressor.

The muffler <NUM> inhibits pressure pulsation of the refrigerant discharged from the compressor <NUM>. The outlet pipe of the compressor <NUM> and the four-way switching valve <NUM> may interpose an oil separator in place of or in addition to the muffler <NUM>. The oil separator is configured to separate lubricant from fluid mixture that contains the lubricant and a refrigerant and is discharged from the compressor <NUM>.

The outdoor heat exchanger <NUM> executes heat exchange between the refrigerant and outdoor air. Examples of the outdoor heat exchanger <NUM> include a fin-and-tube heat exchanger of a cross-fin type and a heat exchanger of a microchannel type. The outdoor heat exchanger <NUM> is provided therearound with an outdoor fan configured to send outdoor air to the outdoor heat exchanger <NUM>.

The expansion mechanism <NUM> is disposed between the outdoor heat exchanger <NUM> and the indoor heat exchanger <NUM> on the refrigerant pipe <NUM> of the refrigerant circuit <NUM>, and expands the incoming refrigerant to be decompressed to have predetermined pressure. Examples of the expansion mechanism <NUM> include an electronic expansion valve having a variable opening degree, and a capillary tube.

The accumulator <NUM> is disposed between a suction port of the compressor <NUM> and the four-way switching valve <NUM> in the refrigerant circuit <NUM>, and is configured to separate the incoming refrigerant into a gas refrigerant and a liquid refrigerant. The gas refrigerant thus separated by the accumulator <NUM> is sucked into the compressor <NUM>.

The four-way switching valve <NUM> is configured to be switchable between a first state indicated by a solid line and a second state indicated by a broken line in <FIG>. The four-way switching valve <NUM> is switched into the first state while the air conditioner <NUM> executes cooling operation, and the four-way switching valve <NUM> is switched into the second state while the air conditioner <NUM> executes heating operation.

<FIG> is a front view (partially sectional view) of an exemplary pressure vessel according to the first embodiment of the present invention. <FIG> is a perspective view of another exemplary pressure vessel.

The pressure vessel depicted in <FIG> is the accumulator <NUM>. The accumulator <NUM> includes a vessel body <NUM>, an inlet pipe <NUM>, and an outlet pipe <NUM>. The vessel body <NUM> constitutes a primary part of the accumulator <NUM> and is configured to contain a refrigerant. The vessel body <NUM> includes a trunk 21a having a cylindrical shape, and two lids 21b and 21c closing both longitudinal ends of the trunk 21a.

The present specification will also refer to an axial direction including a center in a transverse section of a pipe such as the inlet pipe <NUM> or the outlet pipe <NUM>, as a "pipe axial direction". A radial direction of a pipe perpendicular to the pipe axial direction will also be called a "pipe diameter direction". An end or an end surface on a first side in the pipe axial direction of the pipe will also be called a "first end" or a "first end surface", and an end or an end surface on a second side in the pipe axial direction will also be called a "second end" or a "second end surface". Each of the "first end" and the "second end" in the pipe axial direction of the pipe refers to a region positioned at an end in the pipe axial direction of the pipe, such as a region adjacent to the "first end surface" or the "second end surface", and may not necessarily include the "first end surface" or the "second end surface" in the pipe axial direction.

The inlet pipe <NUM> is provided on an upper part of the vessel body <NUM> (the upper lid 21b). The inlet pipe <NUM> has a first end (upper end) in the pipe axial direction, which projects from the vessel body <NUM>. The first end of the inlet pipe <NUM> is connected to the four-way switching valve <NUM> (see <FIG>) via the refrigerant pipe <NUM>. The inlet pipe <NUM> has a second end (lower end) in the pipe axial direction, which is disposed in the vessel body <NUM>.

The outlet pipe <NUM> is disposed on the upper part of the vessel body <NUM> (upper lid 21b) and adjacent to the inlet pipe <NUM>. The outlet pipe <NUM> has a first end (upper end) in the pipe axial direction, which projects from the vessel body <NUM>. The first end of the outlet pipe <NUM> is connected to the compressor <NUM> (see <FIG>) via the refrigerant pipe <NUM>. The outlet pipe <NUM> has a second end (lower end) in the pipe axial direction, which is disposed in the vessel body <NUM>.

The accumulator <NUM> includes two inner pipes <NUM> and <NUM> disposed in the vessel body <NUM>. The inner pipe <NUM> extends downward from the second end of the inlet pipe <NUM>. The inner pipe <NUM> extends downward from the second end of the outlet pipe <NUM>, is bent upward into a U shape in a lower part of the vessel body <NUM>, and extends into the upper part of the vessel body <NUM>.

The pressure vessel depicted in <FIG> is the compressor <NUM>. The compressor <NUM> includes a vessel body <NUM>, an inlet pipe <NUM>, an outlet pipe <NUM>, and an injection pipe <NUM>. The vessel body <NUM> constitutes a primary part of the compressor <NUM> and is configured to contain a refrigerant. The vessel body <NUM> accommodates a motor, a compression mechanism, and the like. The vessel body <NUM> includes a trunk 27a having a cylindrical shape, and lids 27b and 27c closing both longitudinal ends of the trunk 27a.

The inlet pipe <NUM> is provided on an upper part of the vessel body <NUM> (the upper lid 27b). The inlet pipe <NUM> has a first end (upper end) in the pipe axial direction, which projects from the vessel body <NUM>. The first end of the inlet pipe <NUM> is connected to the accumulator <NUM> (see <FIG>) via the refrigerant pipe <NUM>. The inlet pipe <NUM> has a second end in the pipe axial direction, which is disposed in the vessel body <NUM>.

The outlet pipe <NUM> is provided halfway (on the trunk 27a) in a vertical direction of the vessel body <NUM>. The outlet pipe <NUM> has a first end in the pipe axial direction, which projects from the vessel body <NUM>. The first end of the outlet pipe <NUM> is connected to the muffler <NUM> (see <FIG>) via the refrigerant pipe <NUM>. The outlet pipe <NUM> has a second end in the pipe axial direction, which is disposed in the vessel body <NUM>.

The injection pipe <NUM> is provided on the upper part of the vessel body <NUM> (the upper lid 27b). The injection pipe <NUM> causes an intermediate pressure refrigerant to flow from a subcooler or the like (not depicted) into the vessel body <NUM>. The injection pipe <NUM> is accordingly one kind of the inlet pipe <NUM>. The injection pipe <NUM> has a first end in the pipe axial direction, which projects from the vessel body <NUM>. The injection pipe <NUM> has a second end in the pipe axial direction, which is disposed in the vessel body <NUM>.

The inlet pipes <NUM> and <NUM> (including the injection pipe <NUM>) and the outlet pipes <NUM> and <NUM> in the pressure vessels such as the accumulator <NUM> and the compressor <NUM> are structured as described below. In the following description, the inlet pipes <NUM>, <NUM>, and <NUM> and the outlet pipes <NUM> and <NUM> will be collectively called a "first pipe" denoted by reference sign <NUM>. The vessel bodies <NUM> and <NUM> will be denoted by reference sign <NUM> without distinction among the accumulator <NUM>, the compressor <NUM>, and the like.

<FIG> is an enlarged sectional view of a connecting portion between a pipe and the vessel body of the pressure vessel.

A vessel body <NUM> is made of iron. The vessel body <NUM> is provided with an opening <NUM> configured to receive the first pipe <NUM>. The opening <NUM> is constituted by an inner circumferential surface of a sleeve <NUM> bent toward inside the vessel body <NUM> to have a cylindrical shape. The sleeve <NUM> may alternatively be bent toward outside the vessel body <NUM> to have a cylindrical shape. The sleeve <NUM> may exemplarily be formed by burring.

The first pipe <NUM> includes a first portion <NUM> and a second portion <NUM>. The first portion <NUM> is made of stainless steel. The first portion <NUM> is made of SUS304, SUS304L, SUS436L, SUS430, or the like. The first portion <NUM> has a first end 51a in the pipe axial direction, which is disposed outside the vessel body <NUM>. The first portion <NUM> has a second end 51b in the pipe axial direction, at least part of which is disposed in the vessel body <NUM> and is connected to the second portion <NUM>.

The second end 51b of the first portion <NUM> is provided with a minor diameter portion 51c reduced in outer diameter, while a stepped portion 51d is interposed therebetween. The first end 51a of the first portion <NUM> is provided with a major diameter portion 51e increased in outer diameter, while a stepped portion 51f is interposed therebetween. The major diameter portion 51e has an inner circumferential surface provided with a plated portion <NUM> made of a material whose main component is copper. A refrigerant pipe <NUM> made of a material whose main component is copper is brazed with use of a phosphor copper brazing material or the like to the plated portion <NUM>.

The second portion <NUM> is made of copper or copper alloy, which is a material whose main component is copper. The second portion <NUM> has a cylindrical shape. The second portion <NUM> has an inner circumference into which the minor diameter portion 51c of the first portion <NUM> is inserted. The second portion <NUM> has an inner circumferential surface facing an outer circumferential surface of the minor diameter portion 51c of the first portion <NUM> in the pipe diameter direction. The inner circumferential surface of the second portion <NUM> and the outer circumferential surface of the minor diameter portion 51c of the first portion <NUM> are brazed to each other. The inner circumferential surface of the second portion <NUM> and the outer circumferential surface of the minor diameter portion 51c accordingly interpose a brazed portion <NUM> made of a brazing material.

The second portion <NUM> is restricted from moving toward the first side in the pipe axial direction relatively to the first portion <NUM> to be positioned, by the stepped portion 51d positioned at a proximal end of the minor diameter portion 51c. The second portion <NUM> has a second end surface 52b1 in the pipe axial direction, which is disposed closer to the second side in the pipe axial direction (lower side in <FIG>) than a second end surface 51b1 in the pipe axial direction of the first portion <NUM>.

The second portion <NUM> is inserted to the sleeve <NUM> of the vessel body <NUM> and is fixed to the sleeve <NUM>. Specifically, the second portion <NUM> has an outer circumferential surface disposed to face the inner circumferential surface of the sleeve <NUM> of the vessel body <NUM> in the pipe diameter direction. The outer circumferential surface of the second portion <NUM> and the inner circumferential surface of the sleeve <NUM> are brazed to each other. The outer circumferential surface of the second portion <NUM> and the inner circumferential surface of the sleeve <NUM> accordingly interpose a brazed portion <NUM> made of a brazing material.

The second portion <NUM> and the sleeve <NUM> are connected to each other by brazing with use of a brass brazing material. Typical examples of such brazing include burner brazing. The burner brazing is different from "furnace brazing" and is executed manually or with use of a brazing device including a burner.

A conventional pressure vessel includes inlet and outlet pipes made of copper (hereinafter, also called the "inlet pipe and the like") and brazed with use of the brass brazing material to the vessel body <NUM> made of iron. If the inlet pipe and the like are entirely made of stainless steel, connection of the inlet pipe and the like to the vessel body <NUM> made of iron needs a silver brazing material that is more expensive than the brass brazing material. According to the present embodiment, the first pipe <NUM> includes the first portion <NUM> made of stainless steel and the second portion <NUM> made of a material whose main component is copper (made of copper or copper alloy), and the second portion <NUM> is connected to the vessel body <NUM>. Accordingly, similarly to the conventional pressure vessel, the first pipe <NUM> including the first portion <NUM> made of stainless steel can be connected to the vessel body <NUM> by brazing with use of the brass brazing material.

The second portion <NUM> has a first end surface 52a1 in the pipe axial direction, which is disposed closer to the first side in the pipe axial direction (upper side in <FIG>) than a first end in the pipe axial direction, of the sleeve <NUM> of the vessel body <NUM>. The second end surface 52b1 in the pipe axial direction of the second portion <NUM> is disposed closer to the second side in the pipe axial direction (lower side in <FIG>) than a second end surface 62b1 in the pipe axial direction of the sleeve <NUM> of the vessel body <NUM>. The second portion <NUM> accordingly projects from both ends in the pipe axial direction of the sleeve <NUM>.

The second end surface 51b1 in the pipe axial direction of the first portion <NUM> is disposed closer to the second side in the pipe axial direction (lower side in <FIG>) than a second end surface 62b1 in the pipe axial direction of the sleeve <NUM> of the vessel body <NUM>. The minor diameter portion 51c of the first portion <NUM> is disposed to be overlapped with the sleeve <NUM> of the vessel body <NUM> in the pipe diameter direction. Specifically, the minor diameter portion 51c of the first portion <NUM> is overlapped in the pipe diameter direction with entire length L1 in the pipe axial direction of the sleeve <NUM> of the vessel body <NUM>.

The first portion <NUM> and the second portion <NUM> of the first pipe <NUM> are connected by furnace brazing and are placed in a high-temperature environment in a furnace. The second portion <NUM> made of copper may thus have coarsened copper crystal grains to cause strength deterioration. According to the present embodiment, the first portion <NUM> made of stainless steel and the vessel body <NUM> made of iron are disposed to be overlapped with each other in the pipe diameter direction. The second portion <NUM> is not provided by itself where the vessel body <NUM> and the first pipe <NUM> are connected to each other, and the second portion <NUM> is overlapped with at least one of the vessel body <NUM> and the first portion <NUM> in the pipe diameter direction. Strength deterioration of the second portion <NUM> is accordingly compensated with the vessel body <NUM> and the first portion <NUM>.

The second end surface 51b1 of the first portion <NUM> is disposed closer to the first side in the pipe axial direction than the second end surface 52b1 of the second portion <NUM>. The first pipe <NUM> can thus be reduced in entire length in comparison to another case where the second end surface 51b1 of the first portion <NUM> is disposed closer to the second side in the pipe axial direction than the second end surface 52b1 of the second portion <NUM>, in other words, a case where the second end 51b of the first portion <NUM> projects toward the second side in the pipe axial direction than a second end 52b of the second portion <NUM>. This enables increase in the number of first pipes <NUM> simultaneously provided in the furnace for furnace brazing between the first portion <NUM> and the second portion <NUM> of each of the first pipes <NUM>, which achieves improvement in production efficiency of the first pipes <NUM>. The second end surface 51b1 of the first portion <NUM> and the second end surface 52b1 of the second portion <NUM> may alternatively be disposed flush with each other.

The second portion <NUM> may alternatively be provided at the second end 51b of the first portion <NUM> in a state where the second end surface 52b1 is disposed closer to the first side in the pipe axial direction (upper side in <FIG>) than the second end surface 51b1 of the first portion <NUM>, though functional effects described above will not be achieved in this case.

<FIG> is an enlarged sectional view of a connecting portion between a pipe and a vessel body of a pressure vessel according to the second embodiment.

The first pipe <NUM> according to the present embodiment is exemplarily applied to the inlet pipe <NUM> and the inner pipe <NUM> of the accumulator <NUM> depicted in <FIG>. The second portion <NUM> of the first pipe <NUM> depicted in <FIG> is extended into the vessel body <NUM> than the second portion <NUM> of the first pipe <NUM> depicted in <FIG>. In other words, the first pipe <NUM> projecting outward from the vessel body <NUM> also serves as an inner pipe of the vessel body <NUM>. The present embodiment can thus achieve reduction in the number of constituent elements of the pressure vessel in comparison to a case where a different inner pipe is connected to the first pipe <NUM>, for reduction in the number of components and cost reduction. The remaining configurations of the first pipe <NUM> are same as those according to the first embodiment.

<FIG> is an enlarged sectional view of a connecting portion between a pipe and a vessel body of a pressure vessel according to the third embodiment.

The first pipe <NUM> according to the present embodiment is exemplarily applied to the outlet pipe <NUM> and the inner pipe <NUM> of the accumulator <NUM> depicted in <FIG>. The second end 52b in the pipe axial direction of the second portion <NUM> depicted in <FIG> is connected with a different pipe (second pipe) <NUM>. The second pipe <NUM> has a first end 55a in the pipe axial direction, which is provided with a major diameter portion 55b increased in outer diameter while a stepped portion 55c is interposed therebetween. The second end 52b in the pipe axial direction of the second portion <NUM> is inserted to the major diameter portion 55b of the second pipe <NUM>. The outer circumferential surface of the second portion <NUM> faces an inner circumferential surface of the major diameter portion 55b in the pipe diameter direction. The outer circumferential surface of the second portion <NUM> and the inner circumferential surface of the major diameter portion 55b are brazed to each other. The outer circumferential surface of the second portion <NUM> and the inner circumferential surface of the major diameter portion 55b accordingly interpose a brazed portion <NUM> made of a brazing material.

The second pipe <NUM> is made of iron or the like. The second pipe <NUM> can thus be connected to the second portion <NUM> made of a material whose main component is copper, by burner brazing with use of the brass brazing material or the like. As depicted in <FIG>, the inner pipe <NUM> of the vessel body <NUM> is bent into the U shape. If the inner pipe <NUM> and the outlet pipe <NUM> are provided integrally with each other, the inner pipe <NUM> cannot be substantially attached to the vessel body <NUM>. According to the present embodiment as depicted in <FIG>, the inner pipe of the vessel body <NUM> is constituted by the second pipe <NUM> provided separately from the first pipe <NUM>, so that the first pipe <NUM> can be attached to the vessel body <NUM> from outside the vessel body <NUM> (the upper lid 21b in <FIG>) and the second pipe <NUM> can be easily attached to the vessel body <NUM> from inside the vessel body <NUM> (the upper lid 21b in <FIG>).

The second pipe <NUM> may not necessarily be made of iron, and may alternatively be made of a material whose main component is copper. In this case, the second pipe <NUM> can be connected easily to the second portion <NUM> by burner brazing or the like. The second pipe <NUM> may still alternatively be made of aluminum, aluminum alloy, or stainless steel. Note that the second pipe <NUM> made of iron leads to further cost reduction for production of the pressure vessel.

<FIG> is an enlarged sectional view of a connecting portion between a pipe and a vessel body of a pressure vessel according to the fourth embodiment.

The vessel body <NUM> of the pressure vessel according to the present embodiment includes a body <NUM> and a joint tube <NUM>. The body <NUM> and the joint tube <NUM> are made of iron. The body <NUM> constitutes a primary part of the vessel body <NUM> and is configured to contain a refrigerant. The body <NUM> includes a sleeve 64a bent inward. The sleeve 64a has an inner circumferential surface constituting an opening 64b.

The j oint tube <NUM> is provided to attach the first pipe <NUM> to the vessel body <NUM>. The joint tube <NUM> has a cylindrical shape. The joint tube <NUM> is inserted to the sleeve 64a. The joint tube <NUM> has an outer circumferential surface facing the inner circumferential surface of the sleeve 64a. The j oint tube <NUM> is attached to the sleeve 64a by welding. The j oint tube <NUM> extends into the body <NUM> to constitute the inner pipe of the vessel body <NUM>.

The second portion <NUM> of the first pipe <NUM> is connected to the joint tube <NUM>. Specifically, the outer circumferential surface of the second portion <NUM> is disposed to face an inner circumferential surface of the joint tube <NUM>. The outer circumferential surface of the second portion <NUM> is brazed to the inner circumferential surface of the joint tube <NUM> with use of the brass brazing material or the like. The outer circumferential surface of the second portion <NUM> and the inner circumferential surface of the joint tube <NUM> accordingly interpose the brazed portion <NUM>. The first portion <NUM> of the first pipe <NUM> is positioned to be overlapped with the joint tube <NUM> in the pipe diameter direction. The remaining configurations of the first pipe <NUM> are similar to those according to the first embodiment.

According to the present embodiment, the body <NUM> and the joint tube <NUM> of the vessel body <NUM> are firmly connected to each other by welding. The present embodiment is thus suitably applicable to a pressure vessel required to have high compressive resistance, like a compressor having large capacity (horsepower).

<FIG> is an enlarged sectional view of a connecting portion between a pipe and a vessel body of a pressure vessel according to the fifth embodiment.

As in the fourth embodiment, the vessel body <NUM> according to the present embodiment includes the body <NUM> and the joint tube <NUM>. The joint tube <NUM> has a first end in the pipe axial direction, which is connected with the second portion <NUM> of the first pipe <NUM>. The joint tube <NUM> has a second end in the pipe axial direction, which is connected with a different pipe (third pipe) <NUM>.

The third pipe <NUM> is made of a material whose main component is copper (copper or copper alloy). The third pipe <NUM> has an outer circumferential surface facing the inner circumferential surface of the joint tube <NUM> in the pipe diameter direction. The outer circumferential surface of the third pipe <NUM> and the inner circumferential surface of the joint tube <NUM> are brazed to each other with use of the brass brazing material or the like. The outer circumferential surface of the third pipe <NUM> and the inner circumferential surface of the joint tube <NUM> interpose a brazed portion <NUM>. The third pipe <NUM> may not necessarily be made of copper, and may alternatively be made of iron, stainless steel, aluminum, or aluminum alloy.

The inner circumferential surface of the joint tube <NUM> is provided with a protrusion 65a projecting radially inward. The protrusion 65a is provided continuously along the entire inner circumferential surface of the joint tube <NUM>. The protrusion 65a is in contact with the second end surface 52b1 in the pipe axial direction of the second portion <NUM> of the first pipe <NUM> inserted to the joint tube <NUM>. This configuration achieves positioning in the pipe axial direction of the first pipe <NUM> relative to the joint tube <NUM>.

The protrusion 65a is in contact with a first end surface 70b1 in the pipe axial direction of the third pipe <NUM> inserted to the joint tube <NUM>. This configuration achieves positioning in the pipe axial direction of the third pipe <NUM> relative to the joint tube <NUM>.

The second end surface 52b1 in the pipe axial direction of the second portion <NUM> of the first pipe <NUM> is disposed closer to the second side in the pipe axial direction than the second end surface <NUM>1b <NUM> in the pipe axial direction of the first portion <NUM>. This disposition achieves reliable contact between the second end surface 52b1 of the second portion <NUM> and the protrusion 65a. This also prevents any gap between the second portion <NUM> and the third pipe <NUM> in the pipe axial direction. If the second end surface 51b1 of the first portion <NUM> is disposed closer to the second side in the pipe axial direction than the second end surface 52b1 of the second portion <NUM>, there may be provided a space not including the second portion <NUM>, between the outer circumferential surface of the first portion <NUM> and the inner circumferential surface of the joint tube <NUM> in the pipe diameter direction. In such a case, the refrigerant may enter the space to generate unusual sound. The pressure vessel according to the present embodiment can avoid such defectiveness.

The protrusion 65a according to the present embodiment may not necessarily be provided along the entire inner circumferential surface of the joint tube <NUM>, and may alternatively be provided at one circumferential point or at each of a plurality of points circumferentially spaced apart from each other.

<FIG> is an enlarged sectional view of a connecting portion between a pipe and a vessel body of a pressure vessel according to the sixth embodiment.

As in the fourth embodiment, the vessel body <NUM> according to the present embodiment includes the body <NUM> and the joint tube <NUM>. The second portion <NUM> of the first pipe <NUM> is connected to the joint tube <NUM>. The joint tube <NUM> includes a first portion <NUM> and a second portion <NUM>. The first portion <NUM> of the joint tube <NUM> has a cylindrical shape. The first portion <NUM> is inserted to the sleeve 64a of the body <NUM>. The first portion <NUM> is joined to the sleeve 64a by welding.

The second portion <NUM> of the joint tube <NUM> has a cylindrical shape. The second portion <NUM> projects from both ends in the pipe axial direction of the first portion <NUM> of the joint tube <NUM>. The first portion <NUM> and the second portion <NUM> of the joint tube <NUM> are connected to each other by brazing or welding. The second portion <NUM> has a first end in the pipe axial direction, which is provided with a major diameter portion 67a increased in outer diameter while a stepped portion 67b is interposed therebetween. The second portion <NUM> of the first pipe <NUM> is inserted to the major diameter portion 67a. The major diameter portion 67a has an inner circumferential surface, which is connected with the outer circumferential surface of the second portion <NUM> of the first pipe <NUM> by brazing or welding.

The joint tube <NUM> according to the present embodiment includes the first portion <NUM> and the second portion <NUM>, so as to be effective in an exemplary case where the second portion <NUM> has an outer circumferential surface in a complicated shape inapplicable to a shape of the opening 64b of the body <NUM>.

Claim 1:
A pressure vessel providable on a refrigerant circuit (<NUM>),
the pressure vessel comprising a vessel body (<NUM>) made of iron, an inlet pipe causing a refrigerant to flow into the vessel body (<NUM>), and an outlet pipe causing the refrigerant to flow out of the vessel body (<NUM>), wherein
a pipe (<NUM>) corresponding to at least one of the inlet pipe and the outlet pipe includes a first portion (<NUM>) made of stainless steel, a second portion (<NUM>) made of a material whose main component is copper, and a brazed portion (<NUM>) connecting the first portion (<NUM>) and the second portion (<NUM>),
the first portion (<NUM>) has an end (51a) on a first side in a pipe axial direction of the pipe (<NUM>), the end (51a) being disposed outside the vessel body (<NUM>),
the first portion (<NUM>) has an end (51b) on a second side in the pipe axial direction, the end (51b) being connected to the second portion (<NUM>), and
the second portion (<NUM>) is connected to the vessel body (<NUM>).