Joint structure for refrigerant discharge tubes used in hermetic compressors

Abstract

A joint structure for a refrigerant discharge tube of a hermetic reciprocal compressor having a connecting member fit around the refrigerant discharge tube, the connecting member having a shape corresponding to a connecting hole in a cylinder block, thereby allowing the connecting member to be press-caulked. The refrigerant discharge tube is directly connected to the cylinder block. The connecting hole is multi-layered and may be formed into at least two steps. The connecting member is pre-assembled in the connecting hole by transition-fitting. Accordingly, as the connecting member is press-fit in the connecting hole by a caulking-jig, the connecting member is expanded, and the connecting member is more securely fit in the connecting hole. Further, a thread portion having a pitch in a range of 2 to 5 threads is formed on an inner circumference of the connecting hole. Accordingly, the expanded connecting member penetrates into the thread portion, strengthening the connection between the connecting member and the connecting hole. Since the refrigerant discharge tube is directly connected to the cylinder block, structure is simplified, while the number of assembling steps is reduced. As a result, productivity increases and the manufacturing costs decrease. Further, since the connecting member is fit in the connecting hole by the press-caulking instead of the brazing, higher durability is guaranteed and thus, the breakage of the refrigerant discharge tube is prevented.

Description

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention generally relates to a hermetic reciprocal compressor, and more particularly to a joint structure for a refrigerant discharge tube that serves as a passageway for compressed refrigerant.

[0003] 2. Description of the Prior Art

[0004] As shown in FIG. 1, a conventional hermetic reciprocal compressor includes an electronic device unit 20 and a compression device unit 30 in a casing 10 which is formed of an upper shell 11 and a lower shell 12. The compression device unit 30 is driven by the power transmitted from the electronic device unit 20 used to compress the refrigerant.

[0005] The electronic device unit 20 includes in the casing 10a stator 21 which is fixed, a rotor rotatably disposed relative to the stator 21 and a rotary shaft 23 press-fit in the rotor 22 and having an eccentric portion 23a formed at an end thereof.

[0006] The compression device unit 30 includes a cylinder block 31 having a compression chamber 31a, a cylinder head 40 mounted on the cylinder block 31 and having a refrigerant suction chamber 41 and a discharge chamber 42, a piston 50 disposed in the compression chamber 31a of the cylinder block 31 disposed to be movable in a reciprocal fashion, a connecting rod 60, with one end being connected to the piston 50 and the other end connected to the eccentric portion 23a of the rotary shaft 23, for converting and transmitting the rotary motion of the rotary shaft 23 into the linear reciprocal movement of the piston 50, and a valve device 70 disposed between the cylinder block 31 and the cylinder head 40 for controlling the flow of the refrigerant.

[0007] Further, the hermetic reciprocal compressor includes a suction muffler 80 at one side of the interior of the casing 10 for drawing in the refrigerant into the refrigerant suction chamber 41, and a refrigerant discharge tube assembly 90 (FIG. 2) disposed adjacent a refrigerant path hole (not shown) formed in the cylinder block 31 to provide fluid communication with the refrigerant discharge chamber 42 of the cylinder head 40. The refrigerant discharge tube assembly 90 serves as a discharge passageway of the compressed refrigerant.

[0008] As shown in FIG. 2, the refrigerant discharge tube assembly 90 includes a refrigerant discharge tube 91 and a discharge muffler 92. The discharge muffler 92 defines a predetermined space to reduce the noise produced from the pulsation of the refrigerant discharge, and is secured to the cylinder block 31 by a bolt 93. One end of the refrigerant discharge tube 91 is connected to the discharge muffler 92, while the other end is connected to a discharge tube (not shown) provided in the casing 10.

[0009] In the refrigerant discharge tube assembly 90 as described above, the refrigerant discharge tube 91 and the discharge muffler 92 are joined with each other by copper-brazing, and the discharge muffler 92 is coupled with the cylinder block 31 using the bolt 93.

[0010] According to the conventional joint structure for the refrigerant discharge tube, the refrigerant discharge tube 91 and the discharge muffler 92 are joined [with] to each other by copper-brazing, and then the discharge muffler 92 is coupled to the cylinder block 31 by the bolt 93. Accordingly, the number of assembly steps increases, causing the manufacturing efficiency to be reduced and manufacturing costs to increase.

[0011] Also, as the refrigerant discharge tube 91 and the discharge muffler 92 are joined with each other by copper-brazing, the refrigerant discharge tube 91 becomes deformed and phase-variation occurs in the structure in the brazing furnace. As a result, durability of the product deteriorates. Even after the brazing, the neck portion of the refrigerant discharge tube 91 is subject to stress during one or more bending processes, and thus, the refrigerant discharge tube 91 becomes less cylindrical, and stress concentration occurs. As a result, often times, the refrigerant discharge tube 91 is broken, and the refrigerant leaks out of the compressor.

SUMMARY OF THE INVENTION

[0012] Accordingly, it is an object of the present invention to provide a joint structure for a refrigerant discharge tube used in a hermetic reciprocal compressor, which requires fewer operational steps for joining the refrigerant discharge tube relative to the cylinder block, thereby contributing to the improvement of the manufacturing efficiency and to a reduction in manufacturing costs.

[0013] It is another object of the present invention to provide a joint structure for a refrigerant discharge tube used in a hermetic reciprocal compressor, intended to overcome problems of durability deterioration and refrigerant discharge tube breakage which may occur due to copper-brazing, by press-fitting the refrigerant discharge tube to the cylinder block.

[0014] The above objects are accomplished by a joint structure for a refrigerant discharge tube used in a hermetic reciprocal compressor according to the present invention, in which the refrigerant discharge tube is directly connected to a cylinder block by press-caulking a connecting member connected with the refrigerant discharge tube into a connecting hole formed in the cylinder block. The connecting member is formed to correspond to the shape of the connecting hole.

[0015] The connecting hole is formed in a multi-layer or stepped structure, which has at least two layers. For assembly, the connecting member is pre-assembled in the connecting hole by transition-fitting, and then is securely press-fit in the connecting hole by being expanded therein under the pressure of a caulking jig.

[0016] According to the preferred embodiment of the present invention, the connecting hole has a thread portion having a pitch in the range of 2 to 5 threads, and thus, the connecting member is more securely fit in the connecting hole because the connecting member is expanded by the pressure provided by the caulking jig.

[0017] The connecting member can be formed of a soft iron metal or a soft non-iron metal.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The above-mentioned objects and the feature of the present invention will be more apparent by describing the preferred embodiment of the present invention in detail referring to the appended drawings, in which:

[0019] FIG. 1 is a cross-sectional view schematically showing the structure of a conventional hermetic reciprocal compressor;

[0020] FIG. 2 is a perspective detail view showing a joint structure for a refrigerant discharge tube used in the compressor shown in FIG. 1;

[0021] FIG. 3 is a cross-sectional view showing the joint structure for a refrigerant discharge tube used in a hermetic reciprocal compressor according to the preferred embodiment of the present invention;

[0022] FIG. 4 is a cross-sectional view showing the refrigerant discharge tube being connected to the cylinder block by the joint structure according to the present invention; and

[0023] FIG. 5 is a perspective view showing the hermetic reciprocal compressor according to the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

[0024] The objects and other characteristics of the present invention will be made more apparent by describing the preferred embodiments with reference to the accompanying drawings. Elements that are similarly constructed and have similar functions as those like elements of FIGS. 1 and 2 will be identified by identical reference numerals in FIGS. 3-5.

[0025] Referring to FIGS. 3 and 4, the joint structure for the refrigerant discharge tube of the hermetic reciprocal compressor according to the preferred embodiment of the present invention includes a connecting hole 101 penetrated through a side of the cylinder block 100, a refrigerant discharge tube 110 fit in the connecting hole 101 and a connecting member 120 for securing the refrigerant discharge tube 110 relative to the connecting hole 101.

[0026] The connecting hole 101 is formed to be in fluid communication with a refrigerant path hole (not shown) formed inside of the cylinder block 100. The refrigerant path hole is in fluid communication with the refrigerant discharge chamber 42 of the cylinder head 40 (see FIG. 1). The connecting hole 101 is formed having a multi-layer structure in which two or more layers are formed, and may be provided with a thread portion 101a formed in an inner circumference of the hole 101 having a pitch in a range of from 2 to 5 threads.

[0027] The refrigerant discharge tube 110 is inserted in an insertion hole 120a formed in the center of the connecting member 120, and accordingly, the refrigerant discharge tube 110 is connected to the cylinder block 100 as the connecting member 120 is secured to the connecting hole 101.

[0028] The connecting member 120 is also formed having a multi-layer structure corresponding to the shape of the connecting hole 101, and is force-caulked in the connecting hole 101 by a pressing member, such as the caulking jig 130 shown in FIG. 3.

[0029] Preferably, the connecting member 120 is formed of materials having rigidity, but that allow inward or outward expansion by the pressure of the caulking jig 130. Soft iron metal, or soft non-iron metal, can be used as the connecting member 120.

[0030] Hereinbelow, the method of using the joint structure for the refrigerant discharge tube of the hermetic reciprocal compressor according to the preferred embodiment of the present invention will be described.

[0031] First, as shown in FIG. 3, the connecting member 120 is fit in the refrigerant discharge tube 110, and pre-assembled in the connecting hole 101 of the cylinder block 100 by transition-fitting.

[0032] Next, the connecting member 120 is pressed from the rear side by the caulking jig 130, press-fitting the connecting member 120 into the connecting hole 101. At this time, the connecting member 120 expands inwardly and outwardly, coming into close contact with the refrigerant discharge tube 110 relative to the refrigerant discharge tube 110 inserted in the insertion hole 120a of the connecting member 120, with the connecting hole 101 and the connecting member 120 contacting each other very tightly. Due to the presence of the thread portion 101a on the inner circumference of the connecting hole 101, the connecting member 120 penetrates into the threaded portion 101a during expansion, thereby being press-fit in the connecting hole 101 tightly.

[0033] FIG. 4 is a view showing the connecting member 120 being press-caulked in the connecting hole 101. As shown in FIG. 4, the refrigerant discharge tube 110 is secured in the cylinder block 100 due to the expansion of connecting member 120 into the connecting hole 101. As described above, the connecting member 120 is secured in the connecting hole 101 by being expanded under the external pressure of the caulking jig 130 (FIG. 3), and is further tightly secured due to the connecting member 120 being partially and fixedly penetrated into the thread portion 101a formed on the inner circumference of the connecting hole 101. As a result, a strong binding force is acquired, and the connecting member 120 is not separated from the connecting hole 101.

[0034] FIG. 5 shows the hermetic reciprocal compressor having the joint structure for a refrigerant discharge tube as described above. As shown in FIG. 5, the refrigerant discharge tube 110 is directly secured to the cylinder block 100 by the connecting member 120.

[0035] As described above, according to the present invention, since the refrigerant discharge tube 110 is directly connected to the cylinder block 100, the structure becomes simplified, while the number of assembly steps required for assembling the compressor is reduced. As a result, manufacturing efficiency improves and manufacturing costs are reduced.

[0036] Further, since the connecting member is secured by press-caulking, instead of brazing, durability is increased, and thus, breakage of the refrigerant discharge tube 110 can be prevented.

[0037] Although a preferred embodiment of the present invention has been described, it will be understood by those skilled in the art that the present invention should not be limited to the described preferred embodiment, but various changes and modifications can be made to remain within the spirit and scope of the present invention as defined by the appended claims and their equivalents.

Claims

1. A joint structure for a refrigerant discharge tube of a hermetic reciprocal compressor, the refrigerant discharge tube being formed on a cylinder block of the hermetic reciprocal compressor and serving as a passageway for a refrigerant being discharged,

the joint structure comprising:

a connecting hole formed in the cylinder block in fluid communication with a refrigerant path hole formed inside of the cylinder block; and

a connecting member having a shape corresponding to the connecting hole providing for insertion into the connecting hole, whereby

the connecting member is directly connected with the cylinder block by press-caulking of the connecting member in the connecting hole.

2. The joint structure of claim 1, wherein the connecting hole is formed as a multi-layer structure including two or more layers, and the connecting member is pre-assembled in the connecting hole by transition-fitting, whereby the connecting member is completely press-fit in the connecting hole by expansion therein under the pressure of a caulking jig.

3. The joint structure of claim 2, wherein the connecting hole comprises a thread portion having a pitch in a range of 2 through 5 threads, whereby the connecting member is further secured as the connecting member penetrates into the thread portion by being expanded under the pressure of the caulking jig.

4. The joint structure of claim 2, wherein the connecting member is comprised of a soft iron metal.

5. The joint structure of claim 2, wherein the connecting member is comprised of a soft non-iron metal.