Patent Abstract:
A refrigerating machine for a refrigerating appliance, particularly a household refrigerating appliance, includes a compressor, a condenser, a multi-way valve for selectively directing the refrigerant flow through a refrigerant collector from an inlet to a first outlet of the same or through a bypass line while bypassing the first outlet and includes at least one first evaporator. A collecting sieve for intercepting contaminants within the refrigerant flow is placed between the inlet and the first outlet of the refrigerant collector.

Full Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]     This application is a continuation, under 35 U.S.C. § 120, of copending international application No. PCT/EP02/13816, filed Dec. 5, 2002, which designated the United States; this application also claims the priority, under 35 U.S.C. § 119, of German patent application No. 101 62 500.6, filed Dec. 19, 2001; the prior applications are herewith incorporated by reference in their entirety. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to a refrigerating machine, in which a refrigerant header is disposed on a high-pressure side of the refrigerant circuit and to a refrigerator, in particular, household refrigerator, which is equipped with such a refrigerating machine.  
         [0004]     Such a refrigerating machine with a compressor, a condenser, a directional valve for the selective guidance of the refrigerant stream through a refrigerant header from an inlet to a first outlet of the latter or through a secondary line, bypassing the first outlet, and at least one first evaporator are disclosed in European Patent EP 0 703 421 B1. In this known refrigerating machine, a 3/2-way solenoid valve is disposed between the condenser and a series connection of evaporators and makes it possible to supply refrigerant coming from the condenser selectively directly or through a refrigerant header to the evaporators. The refrigerant, which, coming from the condenser, flows through the solenoid valve, is partly gaseous and partly liquid. When it flows through the refrigerant header, the ratio of gaseous to liquid refrigerant corresponds in the latter to the ratio at the outlet of the condenser, and the entire refrigerant present in the refrigerating machine circulates through the evaporators. When the refrigerant is supplied directly from the directional valve to the evaporators, bypassing the refrigerant header, a lower temperature is established in the refrigerant header and leads to the condensation of the refrigerant in the latter. This is extracted from the refrigerant circuit that, thus, operates in an underfilling state. Whereas, when the flow passes through the refrigerant header, the liquid refrigerant is sufficient to cool the series of evaporators as far as the end, in this underfilled state an evaporator at the end of the series remains uncooled. Thus, depending on the state of the directional valve, there can be a changeover between the cooling of all the compartments in the refrigerator and the selective cooling of individual compartments.  
         [0005]     A drier cartridge disposed between the condenser and the inlet of the solenoid valve serves for absorbing from the liquid refrigerant a residual water content that occurs during the filling of the refrigerant circuit. Such a drier cartridge conventionally also contains a fine sieve that is provided for keeping in place a drier substance used in the cartridge, but which also serves for intercepting from the refrigerant stream dirt particles or flux residues that originate substantially from the assembly of the refrigerant circuit and that could otherwise reach the solenoid valve and disturb its functioning capacity.  
         [0006]     Although the drier cartridge, therefore, has an important function substantially only in an early phase of the service life of the refrigerating machine, its flow resistance impedes the circulation of the refrigerant during the entire service life of the machine.  
       SUMMARY OF THE INVENTION  
       [0007]     It is accordingly an object of the invention to provide a refrigerating machine with a pressure-side refrigerant header that overcomes the hereinafore-mentioned disadvantages of the heretofore-known devices of this general type and that improves upon the prior art to achieve effective protection of the solenoid valve against impurities, with as little contribution as possible of the drier cartridge to the overall flow resistance of the refrigerant circuit.  
         [0008]     With the foregoing and other objects in view, there is provided, in accordance with the invention, a refrigerating machine, including a compressor for compressing a refrigerant, a condenser, a refrigerant header having an inlet, a first outlet, and a secondary line bypassing the first outlet, a collecting sieve disposed between the inlet and the first outlet of the refrigerant header for intercepting impurities of a stream of the refrigerant, a directional valve selectively guiding the refrigerant stream through one of the refrigerant header from the inlet to the first outlet and the secondary line; and at least one first evaporator.  
         [0009]     With the objects of the invention in view, there is also provided a refrigerating machine, including a compressor for compressing a refrigerant, a condenser fluidically connected to the compressor, a refrigerant header fluidically connected to the condenser, the header having an inlet, a first outlet, and a secondary line bypassing the first outlet, a collecting sieve disposed between the inlet and the first outlet of the refrigerant header for intercepting impurities of a stream of the refrigerant, a directional valve fluidically connected to the first outlet and to the secondary line and selectively guiding the refrigerant stream through one of the refrigerant header from the inlet to the first outlet, and the secondary line, and at least one first evaporator fluidically connected to the directional valve and to the compressor.  
         [0010]     With the objects of the invention in view, there is also provided a refrigerator having the refrigerating machine according to the invention.  
         [0011]     The collecting sieve provided according to the invention in the refrigerant header may have different affects, depending on the construction of the overall refrigerant circuit of the refrigerating machine. On one hand, when it has the necessary fineness, the collecting sieve in the refrigerant header makes it possible to dispense with a fine sieve for the interception of impurities in the drier and, thereby, to reduce the pressure drop in the refrigerant circuit; to intercept residual moisture and impurities that originate from the assembly of the refrigerant circuit, it is sufficient, in an initial operating phase, to lead the refrigerant through the refrigerant header until the impurities are intercepted completely in the latter and the moisture is intercepted completely in the drier.  
         [0012]     In accordance with another feature of the invention, preferably, the secondary line emanates from a second outlet disposed in the upper region of the refrigerant header, and the first outlet in the refrigerant header is disposed in a lower region of the latter. This makes it possible to separate, purely according to their weight, impurities in the refrigerant header that are to be sieved out, without the refrigerant having to pass across the collecting sieve: impurities that are denser than the refrigerant automatically sink in the refrigerant header and settle on the collecting sieve of the latter, even when the fed-in refrigerant leaves the header again through its second outlet, without passing across the collecting sieve.  
         [0013]     In accordance with a further feature of the invention, the drier precedes the refrigerant header in the refrigerant flow direction and the collecting sieve has a mesh size finer than the fine sieve.  
         [0014]     Preferably, nevertheless, a fine sieve is also provided on the drier, and the drier precedes the directional valve. As such, impurities having different particle sizes can be intercepted at two different sieves with an adapted mesh width, thus, reducing the pressure drop, as compared with the use of an individual sieve where the risk of clogging with particles of different size cannot be ruled out.  
         [0015]     In accordance with an added feature of the invention, the refrigerant header has a second outlet from which the secondary line extends, a lower region, and an upper region, the second outlet is disposed in the upper region of the refrigerant header, and the first outlet is disposed in the lower region of the refrigerant header.  
         [0016]     In accordance with an additional feature of the invention, refrigerant that flows from the inlet to the second outlet of the refrigerant header does not pass across the collecting sieve.  
         [0017]     In accordance with yet another feature of the invention, when the directional valve guides the refrigerant stream through the secondary line, refrigerant flowing from the inlet to the second outlet of the refrigerant header does not pass across the collecting sieve.  
         [0018]     In accordance with yet a further feature of the invention, when the directional valve guides the refrigerant stream through the secondary line, refrigerant flows only from the inlet to the second outlet.  
         [0019]     In accordance with a concomitant feature of the invention, there is provided at least one second evaporator following the first evaporator in a flow direction of the refrigerant; and  
         [0020]     the refrigerant header having a capacity dimensioned so that, in a filled state of the refrigerant header, a refrigerant quantity circulating through the secondary line is already evaporated when the refrigerant quantity reaches the second evaporator.  
         [0021]     Other features that are considered as characteristic for the invention are set forth in the appended claims.  
         [0022]     Although the invention is illustrated and described herein as embodied in a refrigerating machine with a pressure-side refrigerant header, it is, nevertheless, not intended to be limited to the details shown because various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.  
         [0023]     The construction and method of operation of the invention, however, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0024]      FIG. 1  is a perspective view of a household refrigerator with three temperature zones having a refrigerating machine according to the invention; and  
         [0025]      FIG. 2  is a block and schematic circuit diagram of a refrigerant circuit according to the invention and of the electronics provided for regulating the circuit. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0026]     Referring now to the figures of the drawings in detail and first, particularly to  FIG. 1  thereof, there is shown a household refrigerator  10  having a heat-insulating housing  11  and three doors  12 ,  13 ,  14  fastened thereto and pivotable about vertical axes of rotation. The doors  12 ,  13 ,  14  serve for the closing of compartments  17 ,  18 ,  19  that are disposed one above the other, are produced by two spaced-apart intermediate walls  15  and  16 , are separated thermally from one another by these and have different storage temperatures. From the compartments  17 ,  18 ,  19 , the upper compartment  17  closable by the door  12  is configured as a normal cooling compartment. The middle compartment  18  is separated from the upper compartment  17  by the intermediate wall  15 , is capable of being covered by the door  13 , and is configured as a cold storage compartment. The lower compartment  19 , separated thermally from the cold storage compartment  18  by the intermediate wall  16 , serves as a freezing compartment and can be closed by the door  14 . The compartment-specific storage temperature prevailing in the individual compartments  17 ,  18 ,  19  is generated and maintained by a single refrigerant circuit.  
         [0027]     As is evident from  FIG. 2 , to maintain the temperature of the individual compartments  17 ,  18 ,  19 , the refrigerant circuit  20  is equipped with three evaporators  21 ,  22 ,  23  that are disposed one behind the other in a series connection within the refrigerant circuit and are equipped with a different refrigerating capacity and of which the evaporator  21  having the highest refrigerating capacity is associated with the freezing compartment  19  and has an injection point for the refrigerant. The freezing compartment evaporator  21  is followed on the outlet side, in the refrigerant flow direction, by the evaporator  22  that serves for cooling the cold storage compartment  18  and that is followed by the evaporator  23  associated with the normal cooling compartment  17  and having the lowest refrigerating capacity. The evaporator  23  is connected on the outlet side to the suction side of a refrigerant compressor  24  that is followed on the pressure side, in the refrigerant flow direction, by a condenser  25  that is disposed, for example, on the rear side of the housing  11  that faces away from the doors  12 ,  13 ,  14 .  
         [0028]     The condenser  25  is followed on the outlet side by a drier cartridge  26 , in which hygroscopic material is prevented from escaping by a fine sieve  27 .  
         [0029]     The inlet of a refrigerant header  28  is connected to the outlet of the drier cartridge  26  through a pipeline. In the configuration described here, the refrigerant header  28  has a substantially cylindrical shape with a vertical longitudinal axis, similar to the drier cartridge  26 . The inlet for the refrigerant is located at an upper end  29  of the refrigerant header. The refrigerant header  28  has two outlets, a first outlet  30  that is located in the region of its lower end and that refrigerant fed into the header can reach only after passing through a collecting sieve  31  mounted in the refrigerant header, and a second outlet  32  that is located at the upper end  29  of the header  28  in the immediate vicinity of the inlet of the header  28  and from which a secondary line  33  extends to a first inlet of a solenoid valve  34 . A second inlet of the solenoid valve  34  is connected to the first outlet  30  of the refrigerant header  28 .  
         [0030]     The solenoid valve  34  can be changed over by evaluation and regulation electronics  35  between two states in which it connects either the first outlet  30  or the second outlet  32  of the refrigerant header  28  to the freezing compartment evaporator  21  through a throttle  36 .  
         [0031]     In a first switching state of the solenoid valve  34 , in which the first outlet  30  of the refrigerant header  28  is connected to the freezing compartment evaporator  21 , a mixture of gaseous and liquid refrigerant, the mixture originating from the condenser  25 , flows through the entire inner volume of the refrigerant header  28 . The ratio of liquid to gaseous refrigerant in the header  25  in this case corresponds virtually to that at the outlet of the condenser  25 . Under these conditions, the throughput of liquid refrigerant through the header  28  is such that still liquid refrigerant arrives at the evaporator  23  of the cooling compartment  18 , evaporates in the evaporator  23 , and, thus, cools the cooling compartment  18 .  
         [0032]     Particle-like impurities possibly entrained in the refrigerant stream are, in this case, intercepted either at the fine sieve  27  of the drier cartridge  26  or at the collecting sieve  31  of the refrigerant header  28 . Because the flow passes through the fine sieve  27  first, preferably, a larger mesh width is selected for the fine sieve  27  than for the collecting sieve  31  so that the impurities, separated into two fractions according to particle size, are, in each case, intercepted at one of the two sieves, without one of these being clogged to an extent such that this has an appreciable effect on the flow resistance of the refrigerant circuit.  
         [0033]     In a second switching position of the solenoid valve  34 , the refrigerant flows through the refrigerant header  28  from its inlet to the second outlet  32 . The refrigerant can reach the second outlet  32 , without having to pass across the collecting sieve  31  for this purpose; solid impurities possibly entrained in the refrigerant stream sink in the refrigerant header  28  solely by virtue of their density in the refrigerant header  28 , which is high in comparison with the refrigerant, and settle on the collecting sieve  31 . That is to say, even in this state of the solenoid valve  34 , such impurities are filtered out, without the flow, nevertheless, having to pass through the collecting sieve  31  for this purpose.  
         [0034]     In the second switching position of the solenoid valve  34 , liquid refrigerant that collects on the bottom of the refrigerant header  28  is not sucked away; instead, it accumulates in the refrigerant header  28 , with the result that the quantity of refrigerant constantly circulating the refrigerant circuit is reduced. The volume of the refrigerant header  28  is fixed such that when the latter has reached a stationary filling state in the second position of the solenoid valve  34 , the refrigerant quantity circulating the refrigerant circuit is still just sufficient to supply the freezing compartment evaporator  21  and the evaporator  22  of the cold storage compartment with liquid refrigerant, but no longer the evaporator  23  of the normal cooling compartment that, therefore, remains uncooled in the second position of the solenoid valve  34 .  
         [0035]     Control signals that fix the position of the solenoid valve  34  are generated by the evaluation and regulation electronics  35 , not described in detail, which are connected to temperature sensors  37 ,  38  and to a fan  39 . The temperature sensors  37 ,  38  are, for example, NTC sensors that are disposed for detecting the air temperature in the normal cooling compartment  17  and the cold storage compartment  18 , respectively, and that deliver voltage signals representing the detected temperatures to the electronics  36  through lines  40 ,  41 .  
         [0036]     The fan  39  disposed in the cold storage compartment  18  can be switched on and off or its speed regulated by the electronics  35  through a further line  42 , in order, as required, to intensify by a more or less intensive air flow in the cold storage compartment the heat exchange between the latter and the evaporator assigned thereto and, thus, to cool the cold storage compartment  18  to an increased extent. This results in the following possibilities for operating the refrigerant circuit as a function of the temperatures detected by the sensors  17 ,  18 :  
         [0037]     a) operation of the compressor  24  in the first position of the solenoid valve  34 , cooling of all three evaporators  21 ,  22 ,  23 ;  
         [0038]     b) operation of the compressor  24  in the first position of the solenoid valve  34 , with the fan  39  switched on: cooling of all three compartments  17 ,  18 ,  19 , preference being given to the cold storage compartment  18 ;  
         [0039]     c) operation in the second position of the solenoid valve  34 , with the fan  39  switched off: cooling of the freezing compartment  19  and cold storage compartment  18 ; and  
         [0040]     d) operation in the second position of the solenoid valve  34 , with the fan  39  switched on: cooling of the freezing compartment  19  and cold storage compartment  18 , preference being given to the cold storage compartment  18 .  
         [0041]     These four operating modes make it possible to regulate the temperatures in the three compartments  17  to  19  largely independently of one another.  
         [0042]     Of course, as a modification of the example outlined above, the various evaporators  21 ,  22 ,  23  may also be connected in parallel, instead of in series, and be capable of being supplied selectively with refrigerant by different switching positions of the solenoid valve. It is also possible to use a one-piece evaporator board, various regions of which in each case assume the tasks of the evaporators  21 ,  22 ,  23 . In such a case, a subdivision of this evaporator board into portions corresponding to the evaporators  21 ,  22 ,  23  by physical divisions is not necessary; the limit between a region corresponding to the cold storage compartment evaporator  22  and a region corresponding to the normal cooling compartment evaporator  23  may arise simply from the capacity of the refrigerant header  28  and, consequently, from the position of the point on the unitary evaporator board at which the refrigerant is evaporated completely in the second position of the solenoid valve.

Technology Classification (CPC): 5