Compressor suction muffler

Abstract: An electrically-operated sealed compressor includes a cylinder, a cylinder head mounted on the cylinder and having a suction chamber and first and second discharge chambers, a piston accommodated in the cylinder, and a valve mechanism. The valve mechanism includes a suction muffler and a valve plate having at least one suction port, first and second discharge ports, and first and second pass holes. The first discharge port and the first pass hole communicate with the first discharge chamber, while the second discharge port and the second pass hole communicate with the second discharge chamber. The valve mechanism also includes first and second discharge valves mounted on the valve plate and accommodated in the first and second discharge chambers, respectively, a suction reed having a reed valve for selectively opening and closing the suction port, a discharge gasket for sealing the valve plate and the cylinder head, and a discharge muffler. The first and second discharge chambers are separated from each other by the discharge gasket to form respective independent spaces, while the first and second pass holes communicate with the discharge muffler.

Description: Technical Field The present invention relates generally to a relatively compact compressor such as utilized in a refrigerator for home use or a freezer in a show casing and, more particularly, to a valve mechanism or a suction system of such a compressor. Background Art In recent years, a valve mechanism in a compressor have been improved in numerous ways to increase the efficiency of the compressor. However, demands have also been made from the market not only to increase the efficiency of the compressor, but also to suppress noise emission from the compressor. The prior art compressor valve mechanism is disclosed in, for example, the Japanese Laid-open Patent Publication (unexamined) No. 3-175174. Hereinafter, with reference to Figs. 10, 11 and 12, the prior art compressor valve mechanism disclosed in the above mentioned Japanese Laid-open Patent Publication No. 3-175174 will be discussed. Fig. 10 is a sectional view of the prior art valve mechanism in an assembled condition taken along the horizontal direction, Fig. 11 is a longitudinal sectional view of Fig. 10, and Fig. 12 is an exploded view of the prior art valve mechanism. In Figs. 10 to 12, reference numeral 1 represents the valve mechanism, and reference numeral 4 represents a valve plate having two suction ports 2 and two discharge ports 3 both defined therein. A discharge reed valve 22 for selectively opening and closing the discharge ports 3 is retained within a recess 21 defined in the valve plate 4. Reference numeral 23 represents a stopper rivetted at 24 to the valve plate for regulating the lift of the reed valve 22. A suction reed valve 11, a plate-like gasket 12, the valve plate 4, a head gasket 13 and a cylinder head 14 are all bolted to a cylinder 10. The cylinder 10 accommodates therein a piston drivingly coupled with an electric motor (not shown) for axial reciprocating movement within the cylinder 10. The cylinder head 14 has a suction chamber 25 and a discharge chamber 26 defined therein in cooperation with the valve plate 4. The operation of the prior art compressor valve mechanism of the structure described above will now be described. As a result of reciprocating movement of the piston 15, a refrigerant gas within the suction chamber 25 is sucked into the cylinder 10 through the suction ports 2 in the valve plate 4 during opening of the suction reed valve 11 and is subsequently compressed within the cylinder 10 before it is discharged into the discharge chamber 26 in the cylinder head 14 through the discharge ports 3 during opening of the discharge reed valve 22. In the prior art valve mechanism discussed above, however, because the refrigerant gas is simultaneously discharged into the discharge chamber 26 through the two discharge ports 3, refrigerant gas flows interfere with each other to hinder smooth streams of the refrigerant gas, thus lowering the discharge efficiency and the performance of the compressor. Furthermore, because simultaneous discharge of the refrigerant gas from the two discharge ports 3 into the discharge chamber 26 is intermittently performed, very large pulsation and noise are undesirably generated. Also, the discharge reed valve merely has only one resonant mode as streams of the refrigerant gas discharged respectively from the two discharge ports 3 push the discharge reed valve 22 simultaneously and, therefore, it has been difficult to make resonance of the reed valve 22 proper and also to optimize the discharge efficiency at about 3,000 revolutions at 50Hz and also at about 3,600 revolutions at 60Hz. Also, even in the case of the compressor in which the number of revolutions is varied such as an inverter, there has been a problem in that changes in number of revolutions tend to be accompanied by considerable lowering of the efficiency. In addition, since the discharge reed valve 22 merely has the single resonant mode, there has been another problem in that hissing sounds generated by the respective streams of the refrigerant gas discharged from the two discharge ports tend to be enhanced by interference to thereby result in considerable generation of noises. Also, the discharge reed valve 22 is fixed in position within the recess 21 by the stopper 23 and the rivets 24, requiring a complicated mounting and an inefficient assemblage. Japanese Patent Publication (examined) No. 6-74786 discloses a suction system for an electrically-operated sealed compressor in which a muffler having a plurality of chambers partitioned from each other is employed for muffling purpose. However, there has been a problem in that if the muffling feature is given priority, the suction efficiency tends to be lowered accompanied by reduction in performance. Also, since a sucked gas represents an intermittent flow as a result of selective opening and closure of a reed valve, a flow inertia of a refrigerant gas cannot be sufficiently utilized and the charge on a cylinder tends to be lowered. This tendency tends to be enhanced when the muffling performance of the muffler is increased. This sealed compressor requires the muffling performance of the muffler and the suction efficiency to be improved. The present invention has been developed to overcome the above-described disadvantages. It is accordingly an objective of the present invention to provide an improved electrically-operated sealed compressor which has a high discharge efficiency and in which sounds generated as a result of interference of refrigerant gases discharged are of a low level to accomplish noise suppression, and in which pulsation of the refrigerant gas is very small. Another objective of the present invention is to provide an electrically-operated sealed compressor capable of accommodating changes in number of revolutions. A still further objective of the present invention is to provide an electrically-operated sealed compressor in which the discharge valve can easily be mounted to facilitate assemblage. Another objective of the present invention is to provide an electrically-operated sealed compressor in which the stopper and the discharge valve can easily be fixed in position. Still another objective of the present invention is to provide an electrically-operated sealed compressor capable of accomplishing an improvement and maintenance in a muffler over the compressing performance of the compressor without lowering the flow inertia of the refrigerant even if the charge on the cylinder is increased and, hence, the muffling performance is increased. US 5,129,793 discloses a refrigeration compressor incorporating an improved suction muffler. The suction muffler provides dual sound attenuating chambers within a single housing, which housing is secured to the suction inlet conduit extending between the motor cover and suction inlet for the compressor. Integrally formed openings in the sidewall of the conduit provide communication with each of the two chambers and the respective chambers may be tuned to attenuate difference specific frequencies. Internal integrally formed baffles within each of the chambers serve to eliminate standing waves within the chambers as well as adding stiffness to the muffler. Disclosure of the Invention In accomplishing the above and other objectives, an electrically-operated sealed compressor is proposed according to the present invention as defined in claim 1. According to the present invention, an electrically-operated sealed compressor comprises a sealed casing, compressor elements accommodated in the sealed casing and having an electric motor, a cylinder, a piston, and a. crankshaft, a suction muffler accommodated in the sealed casing, a valve plate mounted on one of the compressor elements and having a suction port defined therein, a reed valve for selectively opening and closing the suction port, a passage extending from the suction port to the suction muffler, and a refrigerant flow branch tube opening into a portion of the passage for allowing a sucked gas to flow thereinto and flow out therefrom. The above-described construction has such a function that during closure of the reed valve, the flow inertia in the suction passage is held by the refrigerant flow branch tube, but during opening of the reed valve, a refrigerant gas accumulated by the refrigerant flow branch tube flows into the cylinder to maintain the flow inertia of the sucked gas to thereby maintain and improve the efficiency of charge of the refrigerant into the cylinder. The refrigerant flow branch tube may be accommodated in the suction muffler. This construction has, in addition to the function of maintaining the flow inertia of the sucked refrigerant gas, a capability of simplifying the structure. Another refrigerant flow branch tube may be provided to improve an optimum suction efficiency according to the number of revolutions. According to this construction, the flows of the refrigerant into and out from the refrigerant flow branch tubes during selective opening and closure of the reed valve can be improved by causing a gas column within each refrigerant flow branch tube to resonate according to the number of revolutions of the compressor, to thereby maintain and improve the efficiency of charge of the refrigerant into the cylinder at a particular number of revolutions. Preferably, the refrigerant flow branch tube has an opening disposed in the vicinity of the suction port. This construction has such a function that the flow inertia can be maintained up to the vicinity of the suction port to thereby maintain and improve the efficiency of charge of the refrigerant into the cylinder. Again preferably, the suction muffler has a refrigerant intake port having a cross-sectional area smaller than the suction port. According to this construction, while maintaining the efficiency of charge of the refrigerant into the cylinder, the muffling performance of the muffler can be improved by the refrigerant flow branch tube. In another form of the present invention, an electrically-operated sealed compressor comprises a sealed casing, compressor elements accommodated in the sealed casing and having an electric motor, a cylinder, a piston, and a crankshaft, a suction muffler accommodated in the sealed casing, a valve plate mounted on one of the compressor elements and having a suction port defined therein, a reed valve for selectively opening and closing the suction port, a passage extending from the suction port to the suction muffler, and a closed small chamber formed so as to open into the passage through a branch tube for allowing a sucked gas to flow thereinto and flow out therefrom. Another closed small chamber may be formed so as to open into the passage through another branch tube for allowing a sucked gas to flow thereinto and flow out therefrom. The closed small chamber may be accommodated in the suction muffler. Advantageously, the closed small chamber is open into the passage in the vicinity of the suction port. It is preferred that the suction muffler has an intake port defined therein and having a cross-sectional area smaller than the suction port. According to the above-described construction, when the reed valve opens during a suction stroke, a gas flows into the cylinder and, during subsequent compression stroke, the reed valve is closed. At this time, the internal pressure within the passage leading from the interior of the muffler to the suction port is increased because the flow is abruptly interrupted. The gas of the increased internal pressure is accommodated within the closed small chamber through the branch tube. Accordingly, the inertia of flow can be maintained. Then, during the suction stroke, the accumulated gas immediately flows into the cylinder to give rise to a smooth sucked flow while avoiding reduction of the flow inertia. Brief Description of the Drawings The above and other objectives and features of the present invention will become more apparent from the following description of preferred embodiments thereof with reference to the accompanying drawings, throughout which like parts are designated by like reference numerals, and wherein: Fig. 1 is a sectional view of an electrically-operated sealed compressor according to a third embodiment of the present invention; Fig. 2 is a sectional view taken along line XVI-XVI in Fig. 1; Fig. 3 is a view similar to Fig. 2, but depicting a modification thereof; Fig. 4 is a view similar to Fig. 2, but depicting another modification thereof; Fig. 5 is a view similar to Fig. 2, but depicting a further modification thereof; Fig. 6 is a view similar to Fig. 2, but according to a fourth embodiment of the present invention; Fig. 7 is a view similar to Fig. 6, but depicting a modification thereof; Fig. 8 is a view similar to Fig. 6, but depicting another modification thereof; Fig. 9 is a view similar to Fig. 6, but depicting a further modification thereof; Fig. 10 is a sectional view of an essential portion of a conventional compressor valve mechanism; Fig. 11 is another sectional view of the essential portion of the conventional compressor valve mechanism of Fig. 10; and Fig. 12 is an exploded perspective view of the essential portion of the conventional compressor valve mechanism of Fig. 10. Detailed Description of the Preferred Embodiments Hereinafter, various embodiments of the present invention will be described with reference to the attached figures. (Embodiment 1) Hereinafter, a first embodiment of the present invention will be described with reference to Figs. 1 to 5. Reference numeral 501 represents an electrically-operated sealed compressor in which compressor elements 503 and a compressor unit 505 integrated with an electric motor 504 are elastically supported within upper and lower regions of a sealed casing 502 by means of springs 506. Reference numeral 507 represents a cylinder block wherein a crankshaft 509 is supported by a bearing 508 and a piston 512 is connected to an eccentric portion 510 thereof by means of a connecting rod 511. Reference numeral 513 represents a valve plate provided with a suction port 514 and a discharge port (not shown), and reference numeral 515 represents a reed valve for selectively opening and closing the suction port 514. Reference numeral 516 represents a cylinder head. Reference numeral 517 represents a suction muffler coupled in a passage 518 extending from the suction port 514 to the suction muffler 517. Reference numeral 519 represents a refrigerant flow branch tube provided so as to open into a portion 519' of the passage 518. Reference numeral 520 represents a refrigerant intake port of the suction muffler 517. Reference numeral 521 represents a suction pipe extending through the sealed casing 502 so as to confront the refrigerant intake port 520. The operation of the electrically-operated sealed compressor constructed as hereinabove described will now be described. When the reed valve 515 is open during a suction stroke of the compressor 501, the refrigerant gas flows from the suction muffler 517 into the cylinder through the passage 518. When the piston 512 elevates into a compression stroke, the reed valve 515 is closed to abruptly interrupt the flow of the suction gas within the tube 517, accompanied by an increase in internal pressure, allowing the flow from the opening 519' into the refrigerant flow branch tube 519. During the subsequent suction stroke, a negative pressure is developed within the cylinder to allow the refrigerant gas to be immediately supplied from the refrigerant flow branch tube 519 so that the refrigerant can efficiently be charged into the cylinder without loosing the flow inertia of the refrigerant. Accordingly, there is no possibility that the efficiency of charge into the cylinder becomes worse as a result of the intermittent flow of the sucked refrigerant gas such as occurring in the prior art and the suction efficiency can be maintained and improved. As shown in Fig. 3, a refrigerant flow branch tube 522 may be accommodated within the suction muffler 517, and this can simplify the structure of the muffler 517 along with improvement in suction efficiency. Alternatively, as shown in Fig. 4, refrigerant flow branch tubes 523 and 524 of different lengths are structured integrally with the suction muffler 517 and connected with the passage 518. In such case, where the number of revolutions of the electrically-operated sealed compressor is, for example, 50Hz and 60Hz, it is assumed that the shorter refrigerant flow branch tube 523 and the longer refrigerant flow branch tube 524 are tuned to 60Hz and 50Hz, respectively. Gas columns within the tuned refrigerant flow branch tubes 523 and 524 resonate at the respective numbers of revolutions. During closure of the reed valve 515, the refrigerant gas is charged in the refrigerant flow branch tubes 523 and 524, but during opening of the reed valve 515, the function of the refrigerant flow branch tubes 523 and 524 are accelerated in synchronism with the cycle of flow into the cylinder. By so doing, with the single muffler structure, an optimum suction efficiency can be improved at a plurality of numbers of revolutions. It is to be noted that in the foregoing description, the refrigerant flow branch tubes 523 and 524 have been accommodated within the muffler 517, similar effects can be obtained even though they are structured separately. Alternatively, as shown in Fig. 5, a refrigerant flow branch tube 525 may be accommodated within the suction muffler 517 and opens at 525' in the vicinity of the suction port 514. By so doing, the flow inertia of the sucked refrigerant gas can be maintained and improved in the vicinity of the suction port 514, and the time lag which would occur when the refrigerant gas is charged into the cylinder after having passed from the refrigerant flow branch tube 525 through the suction port 514 during the opening of the reed valve 515 can be minimized to further improve the suction efficiency. It is to be noted that in the foregoing description, the refrigerant flow branch tube 525 has been accommodated within the muffler 517, similar effects can be obtained even though they are structured separately. In Figs. 1 to 5, the refrigerant intake port 520 of the suction muffler 517 is formed so as to have a cross-sectional area smaller than the suction port 514. By the effect of maintenance and improvement of the flow inertia of the refrigerant flow branch tubes 519, 522, 523, 524 and 525, noise can be effectively reduced by throttling the section of the refrigerant intake port 520 which is an outlet for emission of noise into the sealed casing 502, without causing the efficiency of charge of the refrigerant into the cylinder to become worse. As hereinbefore described, according to the present invention, the intermittent flow phenomenon of the refrigerant gas hitherto observed can be lessened and the flow inertia can be maintained and improved, resulting in an improvement in suction efficiency. Also, by integrating the suction muffler and the refrigerant flow branch tube together, the structure can be simplified. In addition, by structuring the plural refrigerant flow branch tubes appropriate to the respective numbers of revolutions, an optimum suction efficiency appropriate to the particular number of revolutions can be obtained. Also, by causing the refrigerant flow branch tube to open in the vicinity of the suction port, the suction efficiency can further be improved. Yet, by rendering the refrigerant intake port of the suction muffler to be smaller than the suction port, noise can effectively be reduced while maintaining the suction efficiency. Thus, as compared with the prior art electrically-operated sealed compressor, advantageous effects of a high efficiency and low noise can be obtained. (Embodiment 2) Hereinafter, a second embodiment of the present invention will be described with reference to Figs. 1 and 6 to 9. In Fig.6, reference numeral 19 represents a refrigerant flow branch tube provided on the passage 518 and having a terminating end coupled with a closed small chamber 530. To describe the operation of the electrically-operated sealed compressor constructed as hereinabove described, when the reed valve 515 is opened during a suction stroke of the compressor 501, the refrigerant gas flows from the suction muffler 517 into the cylinder through the passage 518. When the piston 512 elevates into a compression stroke, the reed valve 515 is closed to abruptly interrupt the flow of the suction gas within the passage 518, accompanied by an increase in internal pressure by the effect of a flow inertia to fill up the closed small chamber 530 through the branch tube 519. Accordingly, no upstream flow of the gas within the passage is halted. During the subsequent suction stroke, the gas within the closed small chamber 530 immediately flows into the branch tube 519. Accordingly, the lag time in which the flow of the sucked gas becomes discontinuous and no initial flow is sufficiently developed such as occurring in the prior art can be reduced, accompanied by an increase in suction efficiency. As shown in Fig. 7, a closed small chamber 533 may be accommodated within the suction muffler 517. This construction is effective to simplify the structure of the muffler in addition to improvement in suction efficiency. Alternatively, as shown in Fig. 8, refrigerant flow branch tubes 534 and 535 of different lengths and closed small chambers 536 and 537 of different volumes are integrally structured with the suction muffler 517 and coupled with the passage 518. In such a case, where the number of revolutions of the compressor differs, with the single muffler structure, an optimum suction efficiency can be increased at a plurality of numbers of revolutions. It is to be noted that the length and diameter of each of the branch tubes 534 and 535 and/or the volume of each of the closed small chambers may not be always limited to those described above and either of them may be changed. Again alternatively, as shown in Fig. 9, not only is a closed small chamber 538 accommodated within the suction muffler 517, but also a refrigerant flow branch tube 539 opens in the vicinity of the suction port 514. With this structure, any possible delay in flow of the gas can further be reduced. Accordingly, because the suction efficiency can be increased, the performance will not or little be reduced even if the section of the intake port 520 of the suction muffler 517 is reduced. Accordingly, by throttling the section of the intake port 520 which provides an outlet through which noise is expelled into the sealed casing 502, the noise can be reduced. As hereinabove described, according to this embodiment of the present invention, the discontinuity of the refrigerant gas hitherto observed in the prior art suction system can be lessened and the suction efficiency can be increased, accompanied by an improvement in muffling performance of the muffler. If the closed small chamber is disposed within the suction muffler, the structure of the suction muffler can be simplified. Also, if the closed small chamber is so structured as to correspond with the number of revolutions, the optimum efficiency can be increased at the plural numbers of revolutions. Moreover, by disposing an opening of the closed small chamber in the vicinity of the suction port, the effect thereof can further be increased. Yet, because in terms of performance the cross-sectional area of the intake port of the suction muffler can be reduced to a value smaller than the suction port, the muffling performance can be sufficiently increased to provide a quiet compressor having a high performance. Although the present invention has been fully described by way of examples with reference to the accompanying drawings, it is to be noted here that various changes and modifications will be apparent to those skilled in the art. Therefore, unless such changes and modifications otherwise depart from the spirit and scope of the present invention, they should be construed as being included therein.

Claims: An electrically-operated sealed compressor (501) comprising: a sealed casing (502); a plurality of compressor elements (503) accommodated in said sealed casing (502) and having an electric motor (504), a cylinder (507), a piston (512), and a crankshaft (509); a suction muffler (517) accommodated in said sealed casing (502); a valve plate (513) mounted on one of said compressor elements (503) and having a suction port (514) defined therein; and a reed valve (515) for selectively opening and closing said suction port (514); characterized by: a passage (518) extending from said suction port (514) to said suction muffler (517); and a refrigerant flow branch tube (519, 522, 523, 525, 534, 539) opening into a portion of said passage (518) for allowing a sucked gas to flow thereinto and flow out therefrom, such that when said reed valve (515) is closed at a compression stroke of said piston (512) in said cylinder (507), an internal pressure of said passage (518) is increased to allow a gas to flow into said refrigerant flow branch tube (519, 522, 523, 525, 534, 539), and when said reed valve (515) is opened at a subsequent suction stroke of said piston (512) in said cylinder (507), the gas drawn into said refrigerant flow branch tube (519, 522, 523, 525, 534, 539) is immediately supplied into said cylinder (507) through said suction port (514). The electrically-operated sealed compressor (501) according to claim 1, wherein said refrigerant flow branch tube (522, 525, 539) is accommodated in said suction muffler (517). The electrically-operated sealed compressor (501) according to claim 1, further comprising a second refrigerant flow branch tube (524, 535) opening into a second portion of said passage (518). The electrically-operated sealed compressor (501) according to claim 1, wherein said refrigerant flow branch tube (519, 522, 523, 525, 534, 539) has an opening disposed adjacent to said suction port (514). The electrically-operated sealed compressor (501) according to claim 1, wherein said suction muffler (517) has a refrigerant intake port (520) having a cross-sectional area smaller than said suction port (514). The electrically-operated sealed compressor (501) according to claim 1 further comprising a closed small chamber (530, 533, 536, 538) formed so as to open into said passage (518) through said refrigerant flow branch tube (519, 522, 523, 525, 534, 539), such that when said reed valve (515) is closed at a compression stroke of said piston (512) in said cylinder (507), an internal pressure of said passage (518) is increased to allow a gas to flow into said small chamber (530, 533, 536, 538) through said refrigerant flow branch tube (519, 522, 523, 525, 534, 539), and when said reed valve (515) is opened at a subsequent suction stroke of said piston (512) in said cylinder (507), the gas drawn into said small chamber (530, 533, 536, 538) is immediately supplied into said cylinder (507) through said suction port (514). The electrically-operated sealed compressor (501) according to claim 6, further comprising a second closed small chamber (537) formed so as to open into said passage (518) through a second branch tube (535). The electrically-operated sealed compressor (501) according to claim 6, wherein said closed small chamber (533, 538) is accommodated in said suction muffler (517). The electrically-operated sealed compressor (501) according to claim 6, wherein said closed small chamber (530, 533, 536, 538) is open into said passage (518) adjacent to said suction port (514). The electrically-operated sealed compressor (501) according to claim 6, wherein said suction muffler (517) has an intake port (520) defined therein and having a cross-sectional area smaller than said suction port (514).

Inventors: KITA ICHIRO, TANAKA YASUHIKO, UMEOKA IKUTOMO, KITA, ICHIRO, TANAKA, YASUHIKO, UMEOKA, IKUTOMO
Applicants: MATSUSHITA REFRIGERATION, MATSUSHITA REFRIGERATION COMPANY
Application year: 1997
Main classification: F04B39
IPC codes: F04B39