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Linear compressorRelated Patent Categories: Pumps, Expansible Chamber Type, Valve Element Mounted In Fixed Chamber Wall Removable With Pumping MemberLinear compressor description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20080063549, Linear compressor. Brief Patent Description - Full Patent Description - Patent Application Claims
[0001] The present invention refers to a linear compressor, in particular intended for use in household-type or industrial-type refrigeration equipment. [0002] In the course of these last few years, owing to an increasingly felt need on the part of refrigeration equipment manufacturers to be able to rely upon the availability of compressors characterized by an ever increasing level of efficiency, there has been a gradual change in the type of compressors used, i.e. manufacturers have gradually moved over from the conventional reciprocating compressors driven by a rotary electric motor to reciprocating compressors of the linear kind, i.e. driven by a linear electric motor as generally consisting of a stator relative to which there is arranged slidably, with a linear reciprocating motion, generated by a magnetic field, a moving element on which there is mounted the piston of the compressor. [0003] Although clearly advantageous from a performance, efficiency and reliability point of view, linear compressors generally present some problems in connection with the ability to actually obtain such favourable characteristics thereof, and these problems may make these compressors rather complex to design and construct. In the first place, unlike conventional compressors, linear compressors do not have any mechanically, i.e. positively determined top and bottom dead centres, so that the need arises here for a special system to be provided to control the position of the piston inside the cylinder, in view of preventing the same pistons from detrimentally knocking against the cylinder head. Such control shall operate to a great accuracy extent in order to ensure that the top dead centre of the piston is situated at an extremely reduced distance from the cylinder head, generally in the order of 0.1 mm, so as to minimize the so-called clearance volume. Any greater distance, even by just a few tenths of a millimetre, would bring about a drastic drop in performance characteristics, so that the need arises here for quite expensive and sophisticated control provisions of an electronic type to be implemented to this purpose. [0004] Moreover, these linear compressors require that a return force proportionate to the displacement of the moving element be available in view of ensuring a correct displacement stroke of the piston, and the simplest method available to ensure this force lies in providing a mechanical spring duly connected to both the stationary base of the compressor and the moving element, such that the thereby obtained mechanical system is capable of working in the way of a forced resonant harmonic oscillator at line frequency; however, linear compressors equipped with a system of this kind generally experience a drastic deterioration in the overall performance characteristics thereof when departing from the resonance condition. [0005] It is to be further noticed that the value of the refrigeration capacity, i.e. cooling effect that can be obtained with linear compressors of the currently known kind cannot be varied to a significant extent, i.e. by a factor of approx. 2, without this implying a considerable performance loss; such variation in the refrigeration capacity may for instance be required in view of particular application-related needs, or even in view of saving energy by adapting the power output of the compressor to the actual refrigeration capacity needed by the refrigerator in a given period of operation thereof. In fact, as this has already been noted above, a variation in the piston stroke entrains a performance loss owing to the constraints deriving from the position of the dead centre relative to the cylinder head and the position of the middle oscillation point of the piston, even the latter being practically unmodifiable without a reduction in motor efficiency and, hence, compressor performance resulting therefrom. Neither a variation in the oscillation frequency of the piston is a feasible option, since it cannot be practiced without incurring a loss in compressor performance, owing to the constraint requiring that the resonance condition of the system be kept unaltered. [0006] It therefore is a main object of the present invention to do away with all of the aforementioned drawbacks of prior-art solutions by providing a linear compressor in which performance and efficiency characteristics are in no connection with, i.e. not tied to and anyway substantially unaffected by construction, design and operating requirements and variations thereof. [0007] A major purpose of the present invention within the above-indicated object thereof is to provide a linear compressor in which the possibility is given to obtain wide variations in the refrigeration power output thereof, without these variations determining a deterioration in the overall performance characteristics of the same compressor. [0008] Another major purpose of the present invention is to provide a linear compressor in which the positioning of the top dead centre of the piston relative to the cylinder head may allow for greater tolerances, without this impairing the general performance characteristics of the compressor, thereby allowing the systems used to control the position of the piston to be simplified and, hence, made far less expensive. [0009] A further major purpose of the present invention is to ensure the possibility for the refrigeration power output of the compressor to be modulated by varying the stroke of the piston, or the oscillation amplitude thereof relative to the midpoint, and the clearance or dead volume, while maintaining energy efficiency values unvaried at a high level. [0010] Another major purpose yet of the present invention is to provide a linear compressor that is significantly simplified in its construction, while at the same time ensuring an unvaried, or possibly even improved, efficiency, along with an improved flexibility in operation as compared to prior-art linear compressors. [0011] A last, although not less important purpose of the present invention is to provide a linear compressor which is low and competitive in costs and capable of being manufactured with the use of readily available machinery and techniques. [0012] According to the present invention, the above indicated aims and advantages, along with further ones that will become apparent from the description given below, are reached in a linear compressor incorporating the features and characteristics as recited in the appended claim 1. [0013] Further features and advantages of the linear compressor according to the present invention may be more readily understood from the description that is given below of a particular, although not sole embodiment, which is illustrated by way of non-limiting example with reference to the accompanying drawings, in which: [0014] FIG. 1 is a longitudinal sectional view of a linear compressor according to the present invention; [0015] FIG. 2 is a detail view of the sectional view of FIG. 1; [0016] FIG. 3 is a diagrammatical view of a schematical representation of the operating cycle of a linear compressor according to the present invention; [0017] FIG. 4 is a view, along a section plane at 90.degree. with respect to FIG. 1, of a linear compressor according to the present invention. [0018] With reference to the above cited and listed Figures, the linear compressor, as generally indicated at 1, comprises a stator body 2 that is substantially constituted by an outer yoke 3, around which there is wound a coil (not shown), and an inner yoke 4 facing the outer yoke 3 and spaced from the latter so as to define an air gap 5. [0019] The linear compressor further comprises a moving element 6 comprising a base plate 7, from which a pair of arms (not shown) extend in a manner known as such in the art, these arms being provided each with a magnet and being accommodated inside the air gap 5. The linear compressor also comprises a shaft 8, to the end portion of which there is firmly joined a piston 9, wherein the base plate 7 is firmly joined to a pan 10, which is in turn connected to a resonance spring 11. [0020] As largely known in the art, energizing the compressor with an alternating current supply gives rise to the generation of a magnetic flux that causes the moving element 6 to perform a reciprocating translatory motion relative to the stator body 2; via the shaft 8, this motion is then transmitted to the piston 9. [0021] The shaft 8 is accommodated slidably within a cylindrical guide body 12 that terminates with a flange 13, which is advantageously obtained integrally with said guide body 12, and against there abuts the liner 14 of a cylinder 15, inside which there is arranged slidably said piston 9. The flange 13 is provided with at least a suction port 16, controlled by suction valve means 17 such as a reed valve, in communication with the suction conduit comprising a conduit 18 connected to a reservoir 19 in which there is collected the gas being taken in, which then flows into the conduit 18 to eventually undergo compression. In an advantageous manner, the suction conduit is fitted between the flange 13 and the stator body 2, so that the inflow of the gas in the cylinder 15 takes place from the side at which the wall temperature is at its lowest. This contributes to reducing the extent to which the gas is heated up during the suction phase, thereby boosting compressor efficiency. [0022] The cylinder 15 is closed by a head 20; the stroke of the piston 9 inside the cylinder 15 is therefore limited, on a side, by the flange 13 and, on the opposite side, by the head 20. The latter is provided with at least an exhaust or delivery port 25 provided with exhaust or delivery valve means 30, e.g. a reed valve, for controlling said delivery port 25. [0023] Inside the cylinder 15, the piston 9 defines a first chamber 21, or a low-pressure chamber as this shall be better explained further on, and a second chamber 22, or a high-pressure chamber as this shall again be better explained further on, in which both of these chambers are variable-volume ones depending on the position of the piston 9 in the cylinder 15; the two chambers 21 and 22 are set in communication with each other via at least a through-aperture 23 provided in the piston 9 and controlled by communication valve means 24, such as a reed valve. [0024] Thanks to the thus obtained configuration, the piston 9 is capable to alternately compress the gas in either direction inside the cylinder 15, thereby generating two compression stages, in which the exhaust or delivery phase in the first low-pressure chamber 21 occurs at the same time as the suction phase in the second high-pressure chamber 22, through the communication aperture 23 and the communication valve means 24 provided in the piston 9. In other words, the compression cycle is split into two stages in phase opposition with respect to each other with a phase shift of 180.degree.. Continue reading about Linear compressor... Full patent description for Linear compressor Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Linear compressor 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. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Linear compressor or other areas of interest. ### Previous Patent Application: Integral filter and float for an electromagnetic pump Next Patent Application: Piston type compressor Industry Class: Pumps ### FreshPatents.com Support Thank you for viewing the Linear compressor patent info. IP-related news and info Results in 0.15253 seconds Other interesting Feshpatents.com categories: Novartis , Pfizer , Philips , Polaroid , Procter & Gamble , 174 |
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