The present invention relates to scroll type fluid machines, and more particularly, to a scroll type fluid machine suited for use in a refrigerating and air-conditioning system or in a heat pump water heater system, and to a method of manufacturing the same.
This type of scroll fluid machine, for example, a hermetic scroll compressor comprises a scroll unit accommodated in a hermetic container and driven by an electric motor to perform a series of processes including suction, compression and discharge of a refrigerant, and suction piping for supplying the refrigerant to the scroll unit from outside of the hermetic container.
The suction piping includes a suction pipe of copper, and a connection pipe and an outer pipe, both made of copper-plated steel.
The connection pipe has an outer end which is located outside of the hermetic container and into which the suction pipe is inserted, and an inner end which is located inside the hermetic container and connected to the scroll unit.
The outer pipe has an outer end into which the suction pipe and the connection pipe are inserted, and an inner end fixed to the hermetic container.
The patent document also discloses a technique wherein, when the outer pipe is joined to the hermetic container by resistance welding, the copper coating plated on the inner peripheral surface of the outer pipe is caused to peel off in the vicinity of the inner end of the pipe due to the electric current flowing during the resistance welding, thus omitting the removal of the flux from inside the hermetic container, which is otherwise required after the outer pipe is brazed to the hermetic container, and thereby preventing corrosion attributable to the residual flux in the hermetic container.
In the conventional techniques disclosed in the patent document, however, the pipes are each obtained by first plating a metallic material with copper, and then cutting and forming the copper-plated material into shape. It is therefore essential that the connection pipe and the outer pipe should be subjected to burring in order to form burrs to be brazed to the suction pipe, which entails increase in the cost of working the suction piping.
Also, in the above conventional techniques, the copper coating plated on the inner peripheral surface of the outer pipe is made to peel off in the vicinity of the inner end of the pipe due to the current that is passed to join the outer pipe to the hermetic container by resistance welding. It is therefore necessary that, with the welding electrode immovably pressed against a portion to be welded, high current should be supplied to the welding portion, as stated in the patent document. This, however, entails increase in the consumption of electric power by the welding operation, and also since the cost of securing safety of the welding operation increases, a problem arises in that the cost of working the suction piping further increases.
In the conventional techniques, moreover, the outer pipe is also subjected to burring so that the flow of high current may be concentrated at the welding portion. Because of the burr of the outer pipe, however, the outer pipe must be inserted from inside the hermetic container and also the welding must be performed on the inner side of the hermetic container. This lowers the assembling efficiency and welding efficiency-of the suction piping, possibly entailing further increase in the cost of working the suction pipe.
The present invention was created in view of the above circumstances, and an object thereof is to provide a scroll type fluid machine of which the piping can be worked at significantly low cost and also can be joined to a hermetic container by resistance welding, and a method of manufacturing the same. This object is achieved by a scroll type fluid machine having the features of claim 1 and by the method of manufacturing a scroll type fluid machine having the features of claim 3. The present invention is further developed as defined in the dependent claims.
In the above scroll type fluid machine, it is unnecessary to carry out removal of flux from within the hermetic container, which is required in cases where the joint is formed by brazing, and thus it is possible to reliably prevent corrosion attributable to the residual flux in the hermetic container.
Further, the boss has the iron-exposed region formed beforehand. Accordingly, during the welding operation, it is unnecessary to supply high current to the boss in order to remove the copper coating, so that the consumption of electric power by the welding operation can be reduced and safety enhanced, improving the assembling efficiency of the piping and also reducing the cost of working the piping.
Preferably, in the above scroll type fluid machine, the joint is formed at a junction between an outer surface of the hermetic container and an outer peripheral surface of the boss.
This structure permits the boss to be fitted from outside of the hermetic container and also allows the welding operation to be performed from the outer side of the hermetic container to form the joint, thus further improving the assembling efficiency of the piping and reducing the cost of working the piping.
In the above scroll type fluid machine, each of the boss and the internal pipe is obtained by forming the iron-based material into shape and then subjecting the shaped material to a copper plating process, and an end face of the boss located opposite the joint is positioned flush with an end face of the internal pipe located outside of the hermetic container.
In this case, the boss and the internal pipe can be collectively joined, at their copper-plated end faces, to the copper-based external pipe by copper brazing, without the need to perform complicated working or machining on the boss and the internal pipe, making it possible to further reduce the cost of working the piping.
Preferably, in the above scroll type fluid machine, a region of the boss is masked prior to the copper plating process, to form the iron-exposed region.
The iron-exposed region of the boss can be formed with ease, whereby the cost of working the piping can be further cut down.
Preferably, in the above scroll type fluid machine, the boss is subjected to the copper plating process, and after the copper plating process, copper coating is removed from a region of the boss to form the iron-exposed region.
In this case, the welding range for forming the joint can be finely adjusted in accordance with a dimensional error of the boss fitted into the through hole, making it possible to further reduce the cost of working the piping.
An embodiment of the present invention will be described below with reference to the accompanying drawings.
The compressor 1 is incorporated into a refrigeration circuit of a refrigerating and air-conditioning system, heat pump hot water system or the like. The refrigeration circuit has a path through which a carbon dioxide refrigerant (hereinafter referred to as refrigerant) is circulated as a working fluid, and the compressor 1 sucks in the refrigerant from the path and discharges the compressed refrigerant into the path.
The compressor 1 includes a hermetic container 2 made of an iron-based metallic material (iron-based material). The hermetic container 2 has a cylindrical barrel 4 opening at opposite ends, and an upper lid 6 and a lower lid, not shown, hermetically fitted in the upper and lower open ends, respectively, of the barrel 4, whereby the interior of the barrel 4 is hermetically sealed. A discharge pressure of the refrigerant prevails in the interior of the barrel 4. A suction pipe (external pipe) 8 is connected to an appropriate portion of the barrel 4 to introduce the refrigerant from the refrigeration circuit into the barrel 4. A discharge pipe 10 is connected to an appropriate portion of the upper lid 6 to discharge the compressed refrigerant from inside the hermetic container 2 to the refrigeration circuit. The suction and discharge pipes 8 and 10 are each a copper pipe made of a copper-based metallic material (copper-based material).
The barrel 4 accommodates a scroll unit 12 and an electrically driven motor (electric motor), not shown, arranged below the scroll unit 12 for driving the unit 12 through a rotary shaft 14.
The scroll unit 12 comprises a movable scroll 16 and a fixed scroll 18, and spiral wraps protrude integrally from respective end plates of the scrolls 16 and 18 toward each other.
The spiral wraps cooperate with each other to suck the refrigerant from the suction pipe 8 into a suction chamber 20 defined in the end plate of the fixed scroll 18, to form a compression chamber. Because of orbiting movement of the movable scroll 16 relative to the fixed scroll 18, the compression chamber moves toward the center of the spiral wraps, accompanying gradual decrease in the volume of the compression chamber, so that a series of processes including suction, compression, and discharge of the refrigerant is carried out.
The movable scroll 16 is prevented from rotating by a rotation-preventing pin, not shown, and thus makes an orbiting motion on a shaft frame 22 fixed to the barrel 4. To cause the movable scroll 16 to make an orbiting motion, a boss 24 protrudes from the back surface of the end plate of the movable scroll 16, and an eccentric shaft 26 is formed integrally with the upper end of the rotary shaft 14 so as to face the boss 24. The boss 24 is supported by the eccentric shaft 26 with a bearing therebetween.
On the other hand, the fixed scroll 18 is fixed to the barrel 4 and serves as a partition separating the compression chamber from a refrigerant discharge chamber 28 defined on the back side of the end plate of the fixed scroll 18.
Specifically, a discharge hole 30 is formed through a central portion of the end plate of the fixed scroll 18 and is opened and closed by a discharge valve 32 attached to the fixed scroll 18 on the same side as the discharge chamber 28. The discharge valve 32 is covered with a cover 34. The cover 34 serves to set the compression chamber off from the discharge chamber 28 and also to suppress noise produced when the discharge valve 32 opens.
In the compressor 1 described above, as the rotary shaft 14 rotates, the movable scroll 16 orbits on the shaft frame 22 relative to the fixed scroll 18. Consequently, the refrigerant introduced into the suction chamber 20 from the suction pipe 8 is guided toward the center of the scroll unit 12 while being compressed in the compression chamber, and the high-pressure refrigerant in the compression chamber.is discharged from the discharge hole 30 into the interior of the hermetic container 2 and then delivered from the discharge chamber 28 to the outside of the compressor 1 through the discharge pipe 10.
As shown in the enlarged view of
The boss 36 is inserted from outside of the barrel 4 into a through hole 4a formed through the barrel 4, and a joint 42 is formed at a junction between an outer surface 4b of the barrel 4 and an outer peripheral surface 36a of the boss 36 to seal up the through hole 4a.
The inner pipe 38 is inserted through the boss 36 and fitted and fixed in a suction hole 18a formed in the fixed scroll 18 and extending from the side surface of the end plate through to the suction chamber 20. The suction pipe 8 has an end portion fitted into the inner pipe 38 and projects from the boss 36 to the outside of the barrel 4.
The boss 36 and the inner pipe 38 are each made of a copper-plated, iron-based metallic material (copper-plated, iron-based material) and obtained by first forming the iron-based material into shape and then plating the shaped material with copper. An outer end face (boss end face) 36b of the boss 36 located outside of the barrel 4 opposite the joint 42 is positioned substantially flush with an outer end face (internal pipe end face) 38a of the inner pipe 38 located outside of the barrel 4. The boss 36 and the inner pipe 38 are collectively joined, at their copper-plated outer end faces 36a and 38a along the entire circumference, to the suction pipe 8, which is a copper pipe, by copper brazing, thus forming a copper-brazed joint 44.
The boss 36 has a copper-plated region 46 plated with copper, and an iron-exposed region 48 where the iron-based material is exposed to permit the joint 42 to be formed by resistance welding.
The copper-plated region 46 covers at least the outer side of the boss 36 including the outer end face 36b, to permit the joint 44 to be formed by copper brazing.
On the other hand, the iron-exposed region 48 is located on the inner side of the boss 36 opposite the outer end face 36b and includes the inner end face 36c. The iron-exposed region 48 extends to the outer peripheral surface 36a of the boss 36 such that the iron-exposed region 48 of the outer peripheral surface 36a extends from the inner end face 38c by a predetermined distance L including at least the formation range of the joint 42.
The distance L is determined beforehand taking into account a length of the boss 36 by which the boss 36 is inserted into the through hole 4a and the formation or welding range of the joint 42. Specifically, prior to the copper plating process, the necessary region of the boss 36 is masked, and then the boss 36 is immersed in a copper plating solution, whereby the length L of the outer peripheral surface 36a, inclusive of the end face 36c, is prevented from being plated with copper, thus forming the iron-exposed region 48 where the joint 42 is to be formed.
Alternatively, the boss 36 may be immersed in its entirety in the copper plating solution, without masking the boss 36, and after the plating process, the copper coating may be removed from the necessary region including at least the formation range of the joint 42, to form the iron-exposed region 48.
As described above, according to the embodiment, the boss 36 is constituted by a copper-plated, iron-based pipe member having the iron-exposed region 48 where the iron-based material is exposed and where the joint 42 is to be formed. Accordingly, the inner pipe 38 and the suction pipe 8 can be joined to the boss 36 by copper brazing, while the joint 42 can be formed by resistance welding. It is therefore unnecessary to remove flux from inside the hermetic container 2, which is required in cases where the joint 42 is formed by brazing, thereby reliably preventing corrosion attributable to the residual flux in the hermetic container 2.
Further, the iron-exposed region 48 of the boss 36 formed beforehand. This makes it unnecessary to supply high current to the boss 36 during the welding operation to cause the copper coating to peel off. The consumption of electric power by the welding operation can therefore be reduced and safety enhanced, thus improving the assembling efficiency of the suction piping 40 and reducing the cost of working the suction piping 40.
Also, the joint 42 is formed at the junction between the outer surface 4a of the barrel 4 and the outer peripheral surface 36a of the boss 36. Accordingly, with the boss 36 inserted from outside of the barrel 4, the welding operation can be performed from the outer side of the barrel 4 to form the joint 42. This improves the assembling efficiency of the suction piping 40 and makes it possible to further reduce the cost of working the suction piping 40.
Further, after the iron-based material for the boss 36 and the inner pipe 38 is formed into shape, the shaped material is plated with copper, and the outer end face 36b of the boss 36 and the outer end face 38a of the inner pipe 38 are positioned so as to be substantially flush with each other. Accordingly, the boss 36 and the inner pipe 38 can be collectively joined, at their copper-plated outer end faces 36a and 38b, to the suction pipe 8 of copper by copper brazing, without the need for complicated working of the boss 36 and the inner pipe 38, whereby the cost of working the suction piping 40 can be further cut down.
Moreover, the iron-exposed region 48 is formed by masking the necessary region of the boss 36 prior to the copper plating process. Thus, the iron-exposed region 48 of the boss 36 can be formed with ease, making it possible to further reduce the cost of working the suction piping 40.
Alternatively, following the copper plating process, the iron-exposed region 48 is formed by removing the copper coating. In this case, the welding range for forming the joint 42 can be finely adjusted in accordance with a dimensional error of the boss 36 fitted into the through hole 4a, whereby the cost of working the suction piping 40 can be cut down.
For example, although in the above description of the embodiment, the suction piping 40 is mentioned as piping, the piping is not limited to the suction piping and may be various types of piping including the discharge pipe connected to the hermetic container.
Also, in the foregoing embodiment, the present invention is applied to the hermetic scroll compressor incorporated in the refrigeration circuit of a refrigerating and air-conditioning system or heat pump water heater system using carbon dioxide as the refrigerant. The present invention can equally be applied to various other machines using different kinds of working fluid and having different applications, such as non-hermetic type compressors and scroll type fluid machines serving as expansion devices.
This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.