The invention relates to a discharge check valve assembly for use with a hermetic scroll compressor.
Scroll compressor machines, which have two intermeshed involutes or scrolls, provide an efficient way to compress fluids, including gases or mixtures thereof. In operation, one of the scrolls is fixed and the other, an orbiting scroll, is driven by a motor so that it orbits in relation to the fixed scroll. Fluid enters the compressor shell through a low-pressure fluid inlet port and exits through a high-pressure discharge port. The low pressure fluid enters the outer pockets defined by the intermeshed scrolls and is moved toward the center of the intermeshed scrolls or spirals, thereby decreasing in volume and increasing in pressure. The compressed fluid is exhausted through the high-pressure discharge port to the refrigeration or cooling system.
Discharge check valves may be installed in the high-pressure discharge port of the compressor shell to prevent the return of high-pressure refrigerant fluid that may cause reverse movement of the orbiting scroll upon shut down of the compressor.
U.S. Pat. No. 5,141,420 and U.S. Pat. No. 6,171,084 both disclose disc type check valves in the discharge port area of a scroll type hermetic compressor. These valves contain a plurality of components, such as a valve housing, a valve seat element, a valve stop, and a valve disc, each of which must be precisely machined to ensure free movement of the valve disc. Typically, these disc type check valves include an unbiased, planar valve disc.
Such disc type discharge valves are mounted prior to, or in connection with, the welding or permanent attachment of a discharge fitting to the compressor shell. The discharge fitting allows the attachment of suitable conduits to the compressor shell from the rest of the refrigeration system. With these known discharge check valves, once the discharge fitting is attached to the compressor shell, the discharge check valves cannot then be added. Moreover, once these known discharge check valves are assembled to the compressor shell, they cannot be removed without also detaching the discharge fitting from the compressor shell.
Further, these disk type valves are not completely tight, due to insufficient closure force on the unbiased valve element and manufacturing tolerances for the valve element and the valve seat. Even if reverse rotation of the compressor can be avoided when the compressor stops, a certain amount of refrigerant will leak back from the high-pressure side of the refrigeration system into the compressor shell.
In multi-compressor systems, this leads to preservation of high pressure in the discharge compartment inside the hermetic shell of the compressor, when the compressor stops. Due to this elevated pressure, restarting the compressor requires a higher than normal starting torque.
It is an object of the invention to provide a leak tight discharge check valve assembly for a hermetic scroll compressor, which is easy and inexpensive to manufacture and to install.
It is a further object of the invention to provide a discharge check valve assembly having a discharge valve subassembly which may be introduced through the discharge fitting after attachment of the discharge fitting to the compressor.
It is another object of the invention to provide a discharge check valve assembly having a discharge valve subassembly which may be removed from the compressor without requiring removal of the permanently attached discharge fitting.
It is even another object of the invention to provide a hermetic scroll compressor with a pressure equalization element for reducing pressure in the high-pressure compartment when the compressor is not operating.
In a first embodiment, a discharge check valve assembly for use with a hermetic scroll compressor having a compressor shell is provided. The discharge check valve assembly includes a valve housing and a valve seat located within the valve housing. The valve housing is configured to mount the discharge check valve assembly to the compressor shell. The discharge check valve assembly also includes a discharge fitting and a valve subassembly. The discharge fitting is configured to mount to the compressor shell and configured to connect to a connecting tube in fluid communication with a high-pressure system. The valve subassembly has a valve member movable between an open position and a closed position. Additionally, the valve subassembly is configured to be inserted through the discharge fitting into the valve housing.
In one aspect, the valve subassembly further includes a valve body defining a bore, a valve member defining a guiding portion slidably receivable in the bore to allow guided movement of the valve member, and a biasing element positioned between the valve member and the valve body for urging the valve member towards the closed position.
In other aspects, the discharge fitting may be integral with the valve housing, or the discharge fitting may be configured to mount to the compressor shell via the valve housing.
In another aspect, the valve housing may be configured such that when the valve housing is mounted to the compressor shell, the valve housing is located substantially outside the compressor shell. Further, the valve subassembly may be configured such that when the valve housing is mounted to the compressor shell, the valve subassembly is located substantially outside the compressor shell.
Alternatively, the valve housing may be configured such that when the valve housing is mounted to the compressor shell, the valve housing is located at least partially inside the compressor shell, and further, the valve subassembly may be configured such that when the valve housing is mounted to the compressor shell, the valve subassembly is located at least partially inside the compressor shell.
The valve body may be attached to the valve housing by one of a brazing method, a welding method, a press-fit method, an adhesive method, or other suitable connecting methods, including the use of mechanical fasteners.
In another aspect, the valve subassembly can be removably inserted through said discharge fitting into the valve housing.
In a further aspect, the valve subassembly also includes a sealing member coupled to the valve member and interposed between the valve member and the valve seat so that, when the valve member is in the closed position, the sealing member is compressed between the valve member and the valve seat.
In an even further aspect, the guiding portion of the valve member extends through the bore of the valve body and a retaining element is coupled to the guiding portion of the valve member to prevent the guiding portion from sliding out of the bore.
In another embodiment, a hermetic scroll compressor may include the inventive discharge valve assembly.
In even another embodiment, a hermetic scroll compressor includes a compressor shell, a compression stage, a delivery valve arrangement, an orifice, a discharge fitting, and pressure equalization means, e.g. at least one pressure equalizing passage. The compressor shell defines an interior volume divided into a low-pressure fluid compartment and a high-pressure fluid compartment. The compression stage has a fixed spiral element and a movable spiral element, the fixed spiral element having an outlet. The delivery valve arrangement is in fluid communication with the outlet of the fixed spiral element. The orifice is formed in the compressor shell to exhaust high-pressure fluid from the compressor. The discharge fitting is affixed over the orifice and configured to provide fluid communication between the high-pressure fluid compartment and a connecting tube in fluid communication with a high-pressure system. The pressure-equalization passage is configured to provide fluid communication between the high-pressure fluid compartment and the low-pressure fluid compartment, wherein the pressure equalization passage is configured to equalize pressures in the high-pressure and low-pressure fluid compartments when the compressor stops.
The hermetic scroll compressor further includes a discharge check valve assembly and a valve subassembly. The discharge valve assembly has a valve housing and a valve seat located within the valve housing, with the valve housing being mounted within the orifice formed in the compressor shell. The valve subassembly includes a valve member movable between an open position and a closed position. Moreover, the valve subassembly is configured to be inserted through the discharge fitting into the valve housing.
The pressure equalization passage may include a lateral passage arranged on the circumferential surface of the fixed spiral element.
In another aspect, the fixed spiral element may include an end plate and an outlet opening extending therethrough, and the pressure equalization passage may be in fluid communication with the outlet opening.
Further, the delivery valve arrangement may include a valve plate coupled to the fixed spiral element, and the pressure equalization passage may extend through the valve plate.
In one aspect, the pressure equalization passage includes a throughbore extending through the end plate of the fixed spiral element. A capillary sleeve may extend at least part-way through the throughbore. Furthermore, the capillary sleeve may project above an upper surface of the end plate.
In another aspect, the end plate of the fixed spiral element may include a protrusion on an upper surface and the pressure equalization passage may extend therethrough.
These and other objects, features and advantages of the present invention will become apparent in light of the drawings and detailed description of various embodiments provided below.
The compression stage 6 includes a fixed spiral element 9 and a movable spiral element 10, these two spiral elements having interpenetrating parts and defining compression pockets 12. A shaft 13 drives the movable spiral element 10 in an orbital movement. Movement of shaft 13 is provided by a motor 14. During the orbital movement of the spiral element 10, the compression pockets 12 define a volume that gradually decreases from the outside, where the fluid is admitted into the low-pressure compartment, towards the inside, the compressed fluids exiting at the centre of the compression stage 6 to the high-pressure compartment 5 through a central outlet opening 11 in the fixed scroll element 9.
The discharge check valve assembly 20 prevents return flow of fluid from the high pressure side of a refrigeration system into the high-pressure compartment 5 and into the compression pockets 12. High pressure in compartment 5 could cause detrimental reverse rotation of the movable scroll element 10 when the compressor stops.
In one embodiment shown in
The valve assembly 20 includes an annular valve seat 22, a valve body 23 having a stop surface 24, a valve member 25 biased towards the valve seat 22 by a biasing element or resilient valve spring 26 arranged between the valve member 25 and the valve body 23. The valve member 25 has an elongated guiding portion 27 slidingly movable within a central bore 28 of the valve body 23.
In
The valve housing 21 includes a first connecting portion 34, which is inserted in the orifice 8 formed in the upper cap 3 of the compressor shell 2. A welding portion 36 comprises a contact surface 37 abutting the outer surface of the upper cap 3. The valve housing 21 is fixed to the cap 3 by welding seam 38. A portion 39 of the housing 21 of increased diameter surrounds the valve member 25, the valve body 23 and the resilient spring 26, and delimits a valve chamber 40. A tubular end portion 41 of valve housing 21 includes on its inner surface a stop flange 42 for the valve body 23. The tubular end portion 41, acting as a discharge fitting 45, further accommodates a connecting tube 60 to provide fluid communication to the refrigeration system (not shown).
The valve body 23 includes a guiding portion 43 defining a central bore 28 and having a radial outer surface 44. The surface of the bore 28 serves as a sliding bearing for the guiding portion 27 of the valve member. The radial outer surface 44 is adapted to the inner diameter of spring 26. An axial end face 24 of the guiding portion serves as a stop surface for the base part 29 and limits the opening movement of the valve member 25. An annular fixation portion 46 having a flange 47 projecting in a radially outward direction and abutting stop flange 42 of the valve housing 21 determines the position of the valve body within housing 21. A plurality of leg members 48 connect the guiding portion 43 and the fixation portion 46 of the valve body, without overly disturbing the flow path of the discharge fluid.
The valve spring 26 is arranged between a surface 49 of the valve body 23 and the base part 29 of the valve member 25. In one aspect of the invention, the spring constant of the valve spring 26 is relatively weak, as the spring essentially only has to compensate for friction losses in the valve body to ensure that the check valve closes when the compressor is not operating. Spring 26 need not be limited to a spiral wound compression spring, as shown in
To minimize pressure losses in the discharge flow, the valve member 25 has in its central portion a conically shaped boss 51. Further, the interior shape of the valve housing 21 is adapted to the conical boss 51 to realize an undisturbed flow path for the discharge fluid within the valve chamber 40 with substantially constant flow cross section through the entire valve assembly.
Where the valve housing 21/discharge fittings 45 in
In
In all of the previously disclosed embodiments, the valve subassembly 35 including the valve member 25, the valve body 23 and the spring 26 is pre-assembled prior to mounting into the valve housing 21. For that purpose, a retaining element 55 (see
As the outer diameter of the valve member 25 and of the entire valve subassembly 35 is less than the inner diameter of the discharge fitting 45 and the inner diameter of the tubular end portion 41 of the housing, the valve subassembly 35 can be inserted into the housing from the side remote to the compressor shell 2 after the discharge fitting 45 has been affixed to the valve housing 21 or to the compressor shell 2. Thus, the valve subassembly 35 can be inserted through the discharge fitting 45 and into the valve housing 21 after finalized, on-site mounting of the compressor. This allows greater flexibility in ordering and installing compressors, in that identical compressors may be operated with or without the discharge check valve subassembly 35 or, alternatively, a compressor originally configured for operation with a discharge check valve assembly may be simply and easily reconfigured for use without a discharge check valve assembly, or vice versa.
In addition, in those embodiments wherein the valve subassembly 35 is not permanently affixed to the valve housing 21, the valve subassembly 35 may be removed from valve housing 21 through the discharge fitting 45 without requiring removal of the permanently attached discharge fitting. This is particularly useful in case of valve failure.
The insertion depth of the valve subassembly 35 is limited by the abutment of flange 47 of the valve body 23 on stop flange 42 of the housing. The valve body 23 may be secured to the housing by means of a press fit, adhesive, brazing or welding between valve body and housing, or other suitable connecting methods, including the use of mechanical fasteners.
During operation of the compressor 1, the high pressure of the discharge fluid from the compression stage will be exerted against the valve member 25 and thereby against the force of the valve spring 26. The high pressure causes the valve member to move towards an open position. When fully open, the valve member may abut the valve body stop surface 24.
When the compressor stops, the high pressure in the discharge line of the system will force the valve member to its closed position and prevent any refrigerant fluids from leaking back into the compressor shell. The valve assembly, according to the invention, also reduces the risk of undesirable reverse rotation of the orbiting scroll set 10 by preventing back flow of refrigerant fluid at high pressure into the compression pockets 12, when the compressor stops.
As shown in
In
In
The same effect of preventing blockage of the pressure equalizing and oil return passage is achieved by the embodiments of
Although the present invention has been described with respect to discharge check valve assemblies for scroll compressors, the claimed invention may be easily adapted for used with any pressurized vessel. Father, although this invention has been shown and described with respect to the detailed embodiments thereof, it will be understood by those skilled in the art that various changes in form and detail thereof may be made without departing from the spirit and scope of the invention.
This application is entitled to the benefit of and incorporates by reference essential subject matter disclosed in Provisional Patent Application Ser. No. 60/565,463 filed on Apr. 26, 2004.
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Number | Date | Country |
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10089277 | Apr 1998 | JP |
Number | Date | Country | |
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20050238518 A1 | Oct 2005 | US |
Number | Date | Country | |
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60565463 | Apr 2004 | US |