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Miniature rotary compressor, and methods related theretoRelated Patent Categories: Pumps, Motor Driven, Electric Or Magnetic Motor, Rotary Expansible Chamber PumpMiniature rotary compressor, and methods related thereto description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20060140791, Miniature rotary compressor, and methods related thereto. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS REFERENCE TO RELATED APPLICATION [0001] This is a non-provisional application claiming the benefit of and priority to provisional patent application Ser. No. 60/640,699 filed on Dec. 29, 2004, which is incorporated herein by reference. TECHNICAL FIELD [0002] The present invention relates generally to rotary compressors, and methods related thereto. Specifically, the present invention pertains to a rolling piston type miniature rotary compressor for use with primary refrigerants as the working fluid, as used in vapor compression systems. This miniature rotary compressor is especially useful in applications that require small and ultralight cooling systems, which can be battery-powered for portability and used in hot environments that are impractical for conventional air conditioning. BACKGROUND [0003] The emergence of new small-scale technologies has created an environment in which conventional space conditioning may be displaced. One area where such displacement may occur is in the thermal management of various electronic components, such as microprocessors, telecommunications, and guidance equipment. Other areas include man-portable systems for thermal protection of aviators, soldiers, emergency response teams, and hazardous materials handlers. The design of these systems place special requirements on cooling system components not previously encountered in stationary refrigeration systems. Due to the special service that these applications require, the compressor and refrigeration system must be ultra-light weight, highly compact, very durable, shock-resistant, and perform safely in different orientations. [0004] Several types of compressors are currently available for use in refrigeration systems. For home refrigerators and air conditioners, rolling piston compressors are commonly used. Rolling piston compressors are also referred to as fixed (or stationary) vane rotary compressors. In such a compressor, the vane does not rotate along with the rotor, but instead reciprocates in a slot enclosed by the stationary part of the compressor. The cylindrical part of the compressor that is mounted on the eccentric shaft is named a rolling piston because it appears to roll on the cylindrical surface of the cylinder wall. During the suction part of the cycle, refrigerant gas is drawn through an inlet port into the compression chamber, increasing the gas volume. During the suction process, the compression stroke takes place in a decreasing volume on the opposite side of the piston and vane. Therefore, gas is compressed due to the eccentric motion of the roller. Discharge flow is controlled via a discharge valve. [0005] While the small size (for a given capacity) of rolling piston compressors is advantageous, the leakage of refrigerant along surfaces of the cylinder wall is disadvantageous. Lubricating oil that is added to the compressor performs two functions essential to the proper functioning of the compressor's pump parts. The first function pertains to the lubrication of the moving parts themselves. The second function pertains to the sealing of all clearances between the moving parts, which minimizes direct gas leakage that can adversely affect the capacity and efficiency of the compressor. [0006] There is a need for a miniature scale rotary compressor suitable for mobile and portable applications, where grid or vehicle power may not be available. Until now, this scale has never before been attained or reduced to practice in a rotary compression device for high internal pressures. In following the scaling laws for compression devices, the miniaturization of such devices have inevitably encountered serious technical hurdles, most notably in the machining of parts and in specifying reasonable dimensional tolerances. During the process of designing a miniature rotary compressor, the dimensions and tolerances of compression elements, including rotating shaft, bearings, roller, vane, and cylinder, must be scaled and apportioned to the pressure and lower flow conditions. Dimensional tolerances and surface finishes are critical in the miniaturization process and have a direct effect on performance variation and repeatability of each compressor. Further, at some point in the process of reducing the size and scale of the compressor parts, it may not be possible to manufacture parts cost-effectively to the stringent dimensional tolerances necessary to match the compressor's performance at the larger scale, or to maintain the same efficiency of the larger scale system. The packaging of these parts within a small control volume also entails numerous technical challenges. [0007] In dynamic turbomachinery components, the size, rotational speed, and the pressure ratio across the machine are all related. Moreover, the design relationships for turbo-machines present a serious problem for a miniature system, as the compact size requires small radii, high reliability requires slow rotation speed, and high efficiency requires large pressure ratio. Thus, miniaturization cannot be easily accomplished while maintaining high efficiency. This problem can be alleviated to some extent through the use of multiple stages, but at the cost of complexity and size. The design of the miniature compressor is further complicated by the requirement of a low mass flow rate, corresponding to the low power required for the electrical motor drive unit. The low flow rate of the refrigerant increases the relative leakage flow rate through various gaps. [0008] The typical design rules that are applicable to conventional size components are not applicable to miniature sized components. Miniaturization produces a larger surface-to-volume ratio of compressor pump parts. In addition, refrigerant losses in a rotary compressor are directly related to the clearances of the machined parts, the surface area required for lubrication, and the lubricant used. Thus, the reduced size will result in a predictable loss of efficiency, unless the design is altered to counter those losses. Further, a simple repackaging of a conventional design will not provide the optimum performance in the miniature scale. The miniature compressor must use a fresh and novel design that is optimized for and accommodate the smaller size and fabrication limitations associated with smaller sizes. [0009] Until recently, existing rotary compressors have been successfully downsized only to a limited degree. Such compressors have relatively large overall size and weight that render them unusable in the emerging areas defined above. The smallest commercially available rotary compressor is about 5 inches (in.) tall, 4 in. in diameter, and weighs more than 5 pounds. Moreover, the efficiency/performance of such a compressor declines as its dimensions and weight are reduced. SUMMARY OF THE INVENTION [0010] Various configurations for rolling piston rotary compressors for standard refrigerants exist at present. However, even the smallest of these known rolling piston rotary compressors are too bulky and/or non-mobile and/or do not provide sufficient cooling effect for applications that require small and ultralight portable compressors. [0011] In view of the above, there is a need for a compact, ultralight, miniature rolling piston rotary compressor for use with standard refrigerants. There is also a need for methods of manufacturing an ultralight, miniature rotary compressor. [0012] It is, therefore, an aspect of the present invention to provide a compact, ultralight, miniature rolling piston rotary compressor having a diameter of up to about 2.5 in., axial length of up to about 3.5 in., weight of up to about 1.7 pounds, and displacement of up to about 3.0 cc/revolution. [0013] It is another aspect of the present invention to provide an ultralight, miniature rolling piston rotary compressor that provides a higher power density and comparable efficiency as compared to state-of-the-art refrigerant-based rotary compressors. [0014] It is another aspect of the present invention to provide an ultralight, miniature rolling piston rotary compressor that is reliable, that can be used with a range of refrigerants and can be produced cost-effectively [0015] It is another aspect of the present invention to provide a miniature rolling piston rotary compressor suitable for portable refrigeration applications, such as personal cooling systems, small refrigerators and freezers, portable blood coolers, beverage coolers, etc. where size, weight, and other factors, such as efficiency, do not inhibit functionality, and for small stationary applications, such as cooling for microprocessors and other electronics components that generate substantial amounts of heat. [0016] It is also an aspect of the present invention to provide methods for manufacturing an ultralight, miniature rolling piston rotary compressor. [0017] The present invention pertains to an ultralight, miniature rolling piston rotary compressor comprising a compressor mechanism, a casing and a brushless DC motor. The miniature rotary compressor's mechanism is housed in a hermetically or semi-hermetically sealed casing. The compressor mechanism comprises a compression cylinder, a shaft having an eccentric part, top and bottom bearings to support the shaft, openings for communicating with lubricant oil, a roller, a vane, and inlet (also referred to as suction) and discharge ports. The compressor mechanism may further comprise an oil pump and an oil separator. The bottom portion of the casing acts as a lubricant oil reservoir. [0018] In one embodiment, a hermetically-sealed miniature rolling piston rotary compressor comprises three housing sections, the top cap, the casing, and the bottom cap, that are preferably joined by welding. In another embodiment, the compressor comprises three or more electrical feedthrough pins, wherein the three or more electrical feedthrough pins are incorporated via sealing with an insulating glass directly into the top cap. [0019] The miniature rotary compressor of the present invention is significantly smaller and lighter than state-of-the art rotary compressors, while providing comparable efficiency/performance. In one embodiment of the present invention, the miniature rolling piston rotary compressor has a diameter of about 2.2 in., axial length of about 2.7 in., and weight of about 1.4 pounds. In another embodiment, the displacement of the miniature rolling piston rotary compressor is 20 percent of the smallest state-of-the-art compressor's displacement. In another embodiment, the physical size volume of the miniature rolling piston rotary compressor is 7.5 percent of the smallest state-of-the-art compressor's size volume. In another embodiment, the oil pump of the miniature rolling piston rotary compressor pumps oil volume that is about 61 percent the oil volume of the state-of-the-art compressor, at comparable motor speeds. In another embodiment, the miniature rolling piston rotary compressor comprises an inlet hole having a diameter that is 76 percent that of the state-of-the-art compressor. In yet another embodiment, the miniature rolling piston rotary compressor comprises an upper flange bearing having a length that is 40 percent that of the state-of-the-art compressor, while the lower flange bearing length is 84 percent that of the state-of-the-art compressor. [0020] In one embodiment, a three-pin feed through for powering the motor drive is assembled and placed within the casing. In another embodiment, a thin-walled compressor casing is utilized while meeting the structural requirements of the ASME Pressure Vessel Code, and the hydrostatic test requirements of UL for hermetic compressors. In another embodiment, a support structure is utilized for the side-mounted outlet connection, which is used to keep the overall axial length to a minimum. In another embodiment, a muffler is incorporated in a way that oil loss is minimized while allowing for the smallest casing axial length and diameter to provide the desired cooling capacity and coefficient of performance. In another embodiment, the motor is fastened to the shaft without the use of heat shrinking. Continue reading about Miniature rotary compressor, and methods related thereto... Full patent description for Miniature rotary compressor, and methods related thereto Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Miniature rotary compressor, and methods related thereto patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. 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