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Linear compressorRelated Patent Categories: Pumps, Motor Driven, Electric Or Magnetic Motor, Reciprocating Rigid Pumping Member, Reciprocating Motor, Unitary Pump And Motor Working MemberLinear compressor description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20070041856, Linear compressor. Brief Patent Description - Full Patent Description - Patent Application Claims
[0001] The invention concerns a linear compressor with a piston reciprocating in a cylinder, a linear motor acting upon the piston and a resonance spring arrangement connected with the piston. [0002] The linear motor of such a linear compressor has a stator and an armature moving in relation to the stator and being connected with the piston. When the armature reciprocates, the piston reciprocates accordingly, thus increasing and reducing a compression chamber in the cylinder. A resonance spring arrangement is connected with the piston or with the armature, said arrangement being adapted to the operation frequency of the linear motor. The linear motor is then operated in the resonance frequency of the spring. [0003] With a piston operated by a rotation motor via a crankshaft, the position of the piston in the upper dead point can be determined accurately. With a linear motor this is not possible. By means of a design of the linear motor, it can be determined for each operation area, where the upper dead point of the piston approximately is, that is, the dead point at which the compression chamber in the cylinder has its smallest extension. As soon as the operation conditions change, for example the pressures in a refrigeration system, which is supplied by the linear compressor, there is a risk that the piston strikes the front side of the cylinder. As usually inlet and outlet valves are located here, such a stroke can cause substantial damage. If a security distance were used, the remaining dead space in the cylinder would be too large, which would reduce the efficiency. [0004] A linear compressor as mentioned in the introduction is known from U.S. Pat. No. 6,783,335 B2. The resonance spring is located on the side of the armature facing away from the piston. An anti-collision device is connected with the resonance spring, said device having an elastic element and a damping element. An excessive movement of the piston will cause the middle section of the resonance spring to strike the damping element, the impact being further damped by the elastic element, which deforms elastically for the damping. However, this does not provide the opportunity of a final setting of a defined end position for the piston. [0005] U.S. Pat. No. 6,056,519 shows a possible embodiment of a resonance spring arrangement. The resonance spring consists of a stack of several plate spring plates, each spring plate having several mutually interlocked spring arms, which are formed by slots in the plates. [0006] U.S. Pat. No. 6,755,627 B2 shows a further linear compressor with an anti-collision device, which is located at the piston side end of the armature, between the stator and the armature. Before reaching the upper dead point of the piston, the armature strikes a spring arm and moves it until the spring arm strikes an elastic damping element. The elastic damping element is still deformable to a certain extent, however, with increased resistance. This does not either provide setting of a defined end position of the piston. [0007] U.S. Pat. No. 6,779,984 B2 proposes a different method. Here a sensor is provided, which indicates the reaching of the upper dead point of the piston. The sensor then controls the electrical supply to the linear motor so that a striking of the piston on the front wall of the cylinder is prevented. Such a control, however, is relatively expensive. [0008] The invention is based on the task of reliably preventing a damaging of the compressor during operation. [0009] With a linear compressor as mentioned in the introduction, this task is solved in that the resonance spring arrangement has a fixed stop allocated to the upper dead point of the piston. [0010] The stop thus provides a well-defined and fixed stop position for the piston in the upper dead point. When the piston is in the upper dead point, the resonance spring arrangement bears on the stop and permits no further movement. A damping element, which could be deformed when reaching the stop, is not available and not necessary either. When the spring bears on the stop, it has already been deformed. The heavier the deformation, the larger the deformation resistance. The impact of the resonance spring arrangement on the stop thus occurs in the area of a lower speed, the impact being, in fact, damped already. [0011] Preferably, the cylinder and the stop are displaceable in relation to each other in the movement direction of the piston during the mounting of the linear compressor. This provides a simple manner of setting the dead space in the cylinder. An external force moves the piston so far that the resonance spring arrangement bears on the stop. The piston is thus in its "upper dead point", that is, in a position, in which the compression chamber in the cylinder shall have its smallest extension. In this position, the cylinder is now displaced so far in relation to the piston that the dead space has the desired minimum volume. In this position the cylinder is then fixed, for example connected with a fixture, which again is connected with the stator of the linear motor. [0012] Preferably, the resonance spring arrangement has at least one plate spring, which gradually comes to rest on the stop, when the piston moves in the direction of its upper dead point. Thus, a sudden impact of the resonance spring arrangement on the stop is avoided. On the contrary, the free spring length is reduced gradually with the movement of the piston towards its upper dead point, which causes that the rigidity of the resonance spring arrangement is accordingly increased. When the plate spring then rests completely on the stop, the piston has reached its upper dead point. When, during the pressure stroke of the compressor, the plate spring can successively roll on the stop, stop noises are reduced and the life of the plate spring is increased. Further, the shape, particularly the inclination, of the stop permits a very accurate setting of the characteristic of the resonance spring system. The same plate springs can also be used for different compressors. The spring properties can then be influenced via the stop. [0013] Preferably, the stop is located in a stop housing, whose extension is adapted to the cross-section of the linear motor. In other words, the stop housing has the same outer diameter as the linear motor, deviations in both directions being possible to a certain extent, as long as the stop housing does not collide with an enclosure, in which the linear motor is adapted. Then, the space provided by the enclosure can be used to its full extent, so that the resonance spring arrangement can be relatively large. [0014] Preferably, the plate spring has in the unloaded state a predetermined distance to the stop housing. Thus, the plate spring can initially move a distance before starting to rest on the stop. [0015] Preferably, the stop has a convex contact surface. Thus, the total width of the spring arms of the plate spring will not come to rest on the stop surface, but only a partial area, as the stop is arched. This may prevent a possible sticking of the plate spring, which might, for example, be caused by a lubrication oil film. Further, excessive tensions in the material of the plate spring are prevented, if the impact of the plate springs on the stop housing does not occur exactly parallel to the stop surface, but with an edge. This also makes it possible to keep the noises small. [0016] Preferably, the plate spring has at least one arched arm. Thus, a relatively long arm can be realised, that is, the length of the arm is not limited by the radius of the stop housing. [0017] It is preferred that the plate spring has several arched arms, which are located and mutually interlocked in the form of several spirals. This provides a simple manner of preventing a tilting moment on the armature or on the piston. The spring rigidity can be increased. A sufficient length is available for all arms. [0018] Preferably, the plate spring has an annular outer section, from which the arms extend radially inwards. The outer section can then be used for fixing the plate spring on the stop housing. The stop housing can, for example, have raised support faces, on which the plate spring bears on the housing. [0019] It is also advantageous, when the outer section has fixing openings, slots separating adjacent arms from each other extending into an area between the fixing openings. Then, also another share of the outer section can be utilised for the length of the spring arms. At the same time, screws can be guided through the fixing openings, which then retain the spring in a correct position in relation to the stop housing. A turning of the plate spring in relation to the spring housing is thus precluded. [0020] Preferably, the plate spring and the stop housing have an auxiliary positioning device, which ensures an allocation by angle of the plate spring and the stop housing in relation to each other. When the plate spring is made with several spiral-shaped arms, it is expedient to ensure that each arm faces a correspondingly spiral-shaped stop in the stop housing. The more accurate the allocation of stop and arm can be ensured, the more accurate is the control of the working behaviour of the linear motor. [0021] Preferably, a central area of the plate spring has an opening, through which is guided an element connected with the piston. Thus, the arms are connected with each other in the middle through the central area. The opening is a simple opportunity of connecting the spring with the piston or with the piston via the armature, respectively. [0022] Preferably, the stop is located on a side of the linear motor facing away from the cylinder. Here, sufficient space is available. Thus, the stop neither prevents the movement of the piston in the cylinder, nor will design measures be required to provide a space for the stop at the cylinder-side end of the linear motor. [0023] In the following, the invention is described on the basis of a preferred embodiment in connection with the drawings, showing: [0024] FIG. 1 a schematic longitudinal view through a linear compressor 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: Rotary compressor Next Patent Application: Linear compressor, particularly refrigerant compressor Industry Class: Pumps ### FreshPatents.com Support Thank you for viewing the Linear compressor patent info. IP-related news and info Results in 0.584 seconds Other interesting Feshpatents.com categories: Canon USA , Celera Genomics , Cephalon, Inc. , Cingular Wireless , Clorox , Colgate-Palmolive , Corning , Cymer , 174 |
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