Patent Application
20090232672
The present invention relates to a refrigerating compressor to be used in a refrigerator, and it also relates to a refrigerating device using the same compressor.
A conventional refrigerating compressor including a feed oil pipe dipped in oil is disclosed in Unexamined Japanese Patent Publication No. H11-303740, for example. The conventional compressor is described hereinafter with reference to
Compressing unit 4 has cylinder block 7 including cylinder 5 and bearing 6; and crankshaft 10 including eccentric section 8 and main shaft 9 which is supported by bearing 6. Eccentric section 8 of crankshaft 10 is connected to piston 11 via connecting rod 12. Piston 11 is inserted reciprocally in cylinder 5.
Valve plate 14 seals an opening end of cylinder 5, and discharging valve 13 is provided to valve plate 14 on the other side of cylinder 5. Valve plate 14 has suction valve 15. A first end of suction muffler 17 communicates with suction valve 15, a second end of suction muffler 17 opens into container 1 via sound deadening space 16.
Eccentric section 8 has feed oil pipe 18 at its lower end, and a first end of oil feed pipe 18 is press-fitted to eccentric section 8 and a second end thereof is dipped in oil 2. Feed oil pipe 18 is formed of a steel pipe, and is bent to form a V-shape including an obtuse angle such that the second end dipped in oil 2 is positioned at the rotating center of main shaft 9.
The operation of the refrigerating compressor having the foregoing structure is described hereinafter. The spin of crankshaft 10 by motor 3 is transmitted to connecting rod 12, so that piston 11 reciprocates. This reciprocation sucks refrigerant into suction muffler 17, and intermittently sucks the refrigerant into cylinder 5 via suction valve 15. The refrigerant flows through an outer cooling circuit (not shown) and is temporarily released into hermetic container 1 before it is sucked into suction muffler 17. The refrigerant sucked into cylinder 5 is compressed by piston 11, and pushes discharge valve 13 open, so that the refrigerant is discharged again into the outer cooling circuit. Oil 2 stored in container 1 is drawn through oil feed pipe 18 by centrifugal force of feed oil pipe 18 placed at the lower end of eccentric section 8 and is delivered to respective sliding sections of compressing unit 4.
In the foregoing structure, eccentric section 8 of crankshaft 10 is vibrated by large intermittent loads applied from connection rod 12 when compressing unit 4 compresses the refrigerant, so that eccentric section 8 repeats bending deformation. The vibration of eccentric section 8 travels to feed oil pipe 18. Then feed oil pipe 18 is vibrated and thus generates resonance sound.
In addition, feed oil pipe 18 rotates in oil 2, thereby agitating oil 2. Oil 2 collides with structural elements of the compressor in container 1, and the flow of oil 2 is thus disturbed, so that no neat eddy is formed. In this status, the refrigerant dissolved in oil 2 foams. This foam collides with feed oil pipe 18 following the disturbance of oil 2, thereby vibrating feed oil pipe 18 and generating the resonance sound. This phenomenon is conspicuous particularly when the refrigerant, e.g. hydrocarbon, dissolved much amount in oil 2 is used.
The vibration due to the resonance of feed oil pipe 18 travels to hermetic container 1 via oil 2, and radiates to the outside of container 1 as noises, so that the refrigerating compressor becomes noisy.
The refrigerating compressor of the present invention has a hermetic container accommodating oil; a motor accommodated in the hermetic container; a compressing unit disposed under the motor, accommodated in the container, and driven by the motor; and a vibration insulating wall. The compressing unit includes a crankshaft, a cylinder block, a piston, a connecting rod, and a feed oil pipe. The crankshaft has a main shaft and an eccentric section. The cylinder block has a bearing for supporting the main shaft rotatably, and a cylinder. The piston reciprocates in the cylinder. The connecting rod connects the piston to the eccentric section. The feed oil pipe is fixed to the eccentric section, and one of its ends is dipped into the oil. The vibration insulating wall is disposed inside of the container at the bottom, and surrounds the feed oil pipe with a given space in between. This structure allows isolating the resonance sound traveling from the pipe to the container, so that a refrigerating compressor with low noises is obtainable.
An exemplary embodiment of the present invention is demonstrated hereinafter with reference to the accompanying drawings. This embodiment does not limit the invention.
Hermetic container 101 stores oil 102 formed of mineral oil at its bottom, and is filled with refrigerant 103 formed of hydrocarbon such as R600a (isobutane). Hermetic container 101 accommodates motor 106 having stator 104 and rotor 105, and compressing unit 107 driven by motor 106. Compressing unit 107 is placed under motor 106.
Next, a structure of compressing unit 107 is described hereinafter. Crankshaft 110 includes main shaft 109, rigidly inserted into rotor 105 of motor 106, and eccentric section 108. Cylinder block 114 includes bearing 111 for supporting main shaft 109 rotatably, and cylinder 113, into which piston 115 is inserted for forming compressing room 112. Cylinder block 114 supports stator 104. Eccentric section 108 of crankshaft 110 is connected to piston 115 by connecting rod 116.
Feed oil pipe 118 (hereinafter referred simply as “pipe 118”) attaches to the lower end of eccentric section 108 such that a first end of pipe 118 is press-fitted to the lower end of eccentric section 108 and a second end is dipped in oil 102 and placed on an extension line of the rotation axis of main shaft 109. Pipe 118 is formed of a steel pipe such as carbon steel pipe for machine construction, and bent at bent section 117 to form a V-shape including an obtuse angle. Feed oil hole 119, into which pipe 118 is press-fitted, communicates with respective sliding sections of compressing unit 107.
A structure of hermetic container 101 is described hereinafter. Hermetic container 101 includes lower container 120 and upper container 121 both formed by drawing hot-rolled sheet steel, for example, and lower and upper containers 120 and 121 are welded at junction 122 by electric welding. Lower container 120 is equipped with discharge pipe 123 and suction pipe 124 both connected to the refrigerating cycle detailed later and shown in
Valve plate 131 seals an opening end of cylinder 113, and discharge valve 130 is provided to valve plate 131 on the other side of cylinder 113. Valve plate 131 is equipped with suction valve 132. A first end of suction muffler 134 communicates with suction valve 132, and a second end of suction muffler 134 opens into hermetic container 101 via sound deadening space 133.
Next, vibration insulating wall 125 disposed in lower container 120 is described hereinafter. Vibration insulating wall 125 is shaped like a cup and is placed inside lower container 120 at the bottom so that it surrounds pipe 118 with a given distance in between. Vibration insulating wall 125 is made of the material such as metal and polybutylene terephthalate resin which is not swelled by refrigerant 103 or oil 102.
Vibration insulating wall 125 is sandwiched by fixing nut 127 and the bottom of lower container 120 with fixing bolt 126. Fixing bolt 126 extends through the bottom of vibration insulating wall 125 and welded to lower container 120 by electric welding. Fixing nut 127 is screwed on bolt 126.
The operation of the refrigerating compressor having the foregoing structure is demonstrated hereinafter. Motor 106 in operation prompts rotor 105 to rotate crankshaft 110, thereby reciprocating piston 115 in cylinder 113 via connecting rod 116. This motion allows refrigerant 103, flowing from heat exchanger 60 shown in
Pipe 118 rotates together with crankshaft 110. The first end of pipe 118 is press-fitted into eccentric section 108 roughly at the center. The second end of pipe 118 is dipped in oil 102 and positioned on the extension line of the rotation axis of main shaft 109, so that the centrifugal force due to the rotation works on oil 102 in pipe 118. This centrifugal force works as pumping force which delivers, via feed oil hole 119, oil 102 inside vibration insulating wall 125 to respective sliding sections of compressing unit 107.
Compression load applied to piston 115 allows applying loads intermittently to eccentric section 108, which thus repeats bending deformation. This deformation of eccentric section 108 travels as vibration to pipe 118, thereby vibrating pipe 118, so that pipe 118 generates resonance. However, in refrigerating compressor 50, vibration insulating wall 125 cuts off the travel of the resonance of pipe 118 to hermetic container 101. As a result, the vibration travelling from pipe 118 to lower container 120 is attenuated, and the noise to be radiated from hermetic container 101 to the outside is suppressed to a lower level.
Vibration insulating wall 125 is preferably made of vibration damping material such as polybutylene terephthalate resin, so that a greater amount of attenuation is obtainable and the noise radiated to the outside of hermetic container 101 can be suppressed to an excessively low level.
It is preferable that communicating hole 128 having a smaller diameter than an inner diameter of pipe 118 is provided at the lower part of vibration insulating wall 125. This structure allows continuous supply of oil 102 from the outside of vibration insulating wall 125 through communicating hole 128 into the inside of vibration insulating wall 125 even if the surface of oil 102 inside wall 125 lowers. As a result, supply of oil 102 is never cut off to the respective sliding sections of compressing unit 107.
Upper end 129 of vibration insulating wall 125 preferably extends upward and exceeds the surface of oil 102. This structure allows oil 102 inside vibration insulating wall 125 to communicate with oil 102 in hermetic container 101 only through communicating hole 128. Hole 128 has a diameter smaller than that of pipe 118 so that no oil shortage occurs inside vibration insulating wall 125, so that few vibrations travel from pipe 118 to hermetic container 101 via communicating hole 128. As a result, vibration insulating wall 125 effectively isolates the resonance of pipe 118.
Next, the situation where bubbles of refrigerant 103 collide with pipe 118, is demonstrated hereinafter. When refrigerating compressor 50 starts operating, the inside of hermetic container 101 is decompressed. As a result, refrigerant 103 dissolved in oil 102 during the halt of refrigerating compressor 50 starts foaming. The bubble of refrigerant 103 generated at this time draws an eddy-like path following the rotation of pipe 118, and the bubbles are drawn to the tip of pipe 118 together with oil 102. At this time, when the bubbles is drawn together with oil 102 disturbed around pipe 118 to the tip of pipe 118, the bubbles collide with the inner and outer walls of pipe 118, so that pipe 118 is greatly vibrated.
Considering the status discussed above, it is preferable that the inner wall of vibration insulating wall 125 shapes like a smooth body of revolution revolving on an extension line of the rotation axis of main shaft 109. This shape is free from inward protrusions, so that oil 102 inside vibration insulating wall 125 rotates in a conical shape without disturbance following the rotation of pipe 118. As a result, drawing a smooth circle, the bubbles of refrigerant 103 in oil 102 approach to the tip of pipe 118, so that collisions between the bubbles and the inside or outside wall of pipe 118 decrease drastically. Oil 102 including the bubbles is thus smoothly drawn into pipe 118, and the resonance of pipe 118 decreases also drastically.
Refrigerant 103 such as hydrocarbon and oil 102 such as mineral oil or alkyl benzene are mutually soluble with each other, so that refrigerant 103 dissolved in oil 102 during the halt of refrigerating compressor 50 abruptly starts foaming when refrigerating compressor 50 starts operating. After this abrupt foaming is finished, refrigerant 103 in oil 102 more or less foams successively during the operation of refrigerating compressor 50.
In this embodiment, refrigerant 103 easy to foam is combined with oil 102. A noise level of hermetic container 101 due to resonance can be lowered even if the resonance of pipe 118 frequently occurs due to the collision between the bubbles and pipe 118 with this combination. This is because vibration insulating wall 125, formed of the vibration damping member, efficiently damps the vibration travelling in oil 102, thereby reducing drastically the vibration transmitted to the outside of vibration insulating wall 125. As discussed above, even use of pipe 118, weakening the noise of refrigerating compressor 50 to an excessively low level is allowed. Pipe 118 made of a steel pipe such as a carbon steel pipe for machine construction is just bent at bent section 117 to form a V-shape including an obtuse angle, so that pipe 118 is obtainable at a high productivity.
Pipe 118 violently agitates oil 102, which thus splashes from the oil surface, so that the oil drops scatter. This particular case is described hereinafter. When pipe 118 rotates in oil 102 during the operation of refrigerating compressor 50, the centrifugal force works on oil drops attached to the outer wall of pipe 118. This centrifugal force sometimes produces oil drops splashed and separated from the oil surface of oil 102. The oil drop, in general, splashes along the outer rim of pipe 118 and collides with hermetic container 101 or compressing unit 107, thereby causing noises.
Upper end 129 of vibration insulating wall 125 preferably extends upward and exceeds bent section 117 of pipe 118. This structure allows the inner face of vibration insulating wall 125 to catch the oil drops splashed by pipe 118, so that the scatter of oil drops is prevented from colliding with hermetic container 101 or compressing unit 107. As a result, noises can be prevented.
In this embodiment, vibration insulating wall 125 made of resin such as polybutylene terephthalate resin is used; however, vibration damping steel plate or rubber such as nitrile-butadiene rubber can be used instead of the resin, and these materials produce an advantage similar to what is discussed above. Cold-rolled sheet steel, which is inexpensive and highly formable, can be used as the material of vibration insulating wall 125 with an advantage similar to the foregoing one.
A refrigerating compressor of the present invention is useful for a refrigerating device to be used in a home-use refrigerator which requires quiet operation, and it is applicable to business-use refrigerators to be used in hotels or a medical care industry.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2005-198325 | Jul 2005 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2006/313621 | 7/3/2006 | WO | 00 | 1/31/2007 |
