Abstract:
A refrigerant compressor that includes a compressor housing enclosing an outlet chamber and an outlet passage leading from the outlet chamber to an external high pressure connection, such that the pulsations in it are damped as much as possible. The refrigerant compressor includes a pulsation damping element inserted into the outlet passage of the compressor housing following the outlet chamber. The pulsation damping element has an inlet baffle which faces the outlet chamber and extends over a cross section of the outlet passage and, located opposite to the inlet baffle is an outlet baffle which extends over the cross section of the outlet passage. At least one reflection chamber is provided between the inlet baffle and the outlet baffle. The inlet baffle and the outlet baffle each have at least one passage which faces a reflection surface on the respectively other baffle.

Description:
This patent application claims the benefit of German applications No. 10 2005 024 765.2, filed May 23, 2005 and No. 10 2005 029 760.9, filed Jun. 20, 2005, the teachings and disclosure of which are hereby incorporated in their entirety by reference thereto. 
     BACKGROUND OF THE INVENTION 
     The invention relates to a refrigerant compressor, in particular, a displacement compressor, such as, for example, a piston compressor or scroll compressor, comprising a compressor housing with an outlet chamber enclosed by it and an outlet passage leading from the outlet chamber to an external high pressure connection. 
     Refrigerant compressors of this type are known from the state of the art. With these refrigerant compressors, particularly when they are piston compressors, pulsations propagate from the outlet chamber and into the adjoining pipe system and these lead, on the one hand, to undesired noises in the pipe system and, on the other hand, to mechanical stressing of the pipe system on account of the pressure peaks. 
     The object underlying the invention is, therefore, to improve a refrigerant compressor of the generic type in such a manner that the pulsations in it are damped to as great an extent as possible. 
     SUMMARY OF THE INVENTION 
     This object is accomplished in accordance with the invention, in a refrigerant compressor of the type described at the outset, in that a pulsation damping element is inserted into the outlet passage of the compressor housing following the outlet chamber, that the pulsation damping element has an inlet baffle which faces the outlet chamber and extends over a cross section of the outlet passage and, located opposite thereto, an outlet baffle which extends over the cross section of the outlet passage, that at least one reflection chamber is provided between the inlet baffle and the outlet baffle and that the inlet baffle and the outlet baffle each have at least one passage which faces a reflection surface on the respectively other baffle. 
     The advantage of the solution according to the invention is to be seen in the fact that the damping element may be inserted into the outlet passage in the cylinder head and, therefore, requires relatively little space, particularly due to the fact that the damping element has no independent, large damping chamber but rather interacts with the outlet chamber with respect to the volume required for damping. 
     The damping element according to the invention suppresses any coupling between the outlet chamber acting in a mechanical analogy as a spring for the pulsations and the amount of refrigerant in the pipe system effective as mass in a mechanical analogy and so, as a result, pulsations can be suppressed in an optimum manner. 
     A particularly favorable solution provides for the damping element to be designed such that stationary waves which extinguish one another at a higher harmonic of a basic frequency of the refrigerant compressor are formed in this damping element. The advantage of this solution is to be seen in the fact that the damping element can be of a space-saving design since it is merely configured such that the stationary waves which extinguish one another and are formed in the element are not of the basic frequency but rather of a higher harmonic of the basic frequency of the refrigerant compressor, wherein this is sufficient for the suppression of the pulsations since the pulsations in the pipe system do not occur with the basic frequency but rather with a higher harmonic of the basic frequency and so it is not necessary to configure the damping element such that stationary waves of the basic frequency which extinguish one another can be formed in the element which would result in the damping element needing to be designed with a very large volume. On the contrary, the configuration of the damping element is sufficient for stationary waves which extinguish one another at a higher harmonic of the basic frequency which should, however, include the higher harmonics of the basic frequency, at which the pulsations primarily occur. 
     It is even more advantageous when several stationary waves, which extinguish one another and which correspond to different higher harmonics of the basic frequency, are formed in the damping element. This solution therefore allows a so-called “wide-band decoupling” of the pipe system from the outlet chamber due to the provision of stationary waves which extinguish one another at several different harmonics of the basic frequency. 
     The basic frequency is to be understood in conjunction with the present invention as the frequency which corresponds to the product of the rotational speed of the refrigerant compressor multiplied by the number of discharges of refrigerant per rotation into the respective outlet chamber. 
     In principle, the passage could be provided as an opening in the inlet baffle and in the respective outlet baffle. 
     A particularly favorable solution provides, however, for the at least one passage to be formed in each of the baffles as a piece of pipe reaching as far as the reflection chamber. 
     In this respect, this piece of pipe preferably faces the reflection surface provided on the respectively other baffle. 
     Such a passage has, in particular, an inner opening, at which a jump in cross section towards the reflection chamber in relation to the passage results, i.e., that each of the at least one passages opens into a reflection chamber between the inlet baffle and the outlet baffle with a jump in cross section. 
     As a result, the damping effect of the damping element may be optimized in a simple manner. 
     In this respect, the inner opening is arranged at a distance from the respectively other baffle. 
     In this respect, the inner opening is preferably located closer to the respectively other baffle than to the baffle having the respective passage. 
     It is provided, in particular, for the at least one piece of pipe of the one baffle to be arranged so as to overlap with the piece of pipe of the respectively other baffle with an inner end area. 
     In this respect, the pieces of pipe are preferably connected to one another in the region of the inner end areas. 
     With respect to the flow cross sections of the passages in the respective baffles, no further details have been given so far. It is particularly advantageous, for example, when the at least one passage in the one baffle has approximately the same flow cross section as the at least one passage in the other baffle. 
     One particularly advantageous embodiment of a refrigerant compressor according to the invention provides for the inlet baffle to have several passages. 
     When providing several passages, it would be conceivable, for example, to arrange these as desired in the inlet baffle. 
     In this respect, it is particularly advantageous when the several passages are arranged around a central axis of the damping element. 
     A particularly favorable solution from a constructional point of view provides for the several passages to be arranged around the central axis in a rotationally symmetric manner. 
     In addition, it is likewise advantageous when the outlet baffle has several passages. 
     It is favorable, in particular, when the several passages of the outlet baffle are arranged around the central axis of the damping element. 
     It is also particularly expedient with this solution when the several passages of the outlet baffle are arranged around the central axis in a rotationally symmetric manner. 
     An optimum solution with respect to the flow ratios provides for the sum of the flow cross sections of the at least one passage of the inlet baffle to amount to more than 25% of a flow cross section of the outlet passage. 
     It is even better when the sum of the flow cross sections of the at least one passage of the inlet baffle amounts to more than 40% of the flow cross sections of the outlet passage. 
     Furthermore, it is also favorable when the sum of the flow cross sections of the at least one passage of the outlet baffle amounts to more than 25% of the flow cross section of the outlet passage. 
     It is even better when the sum of the flow cross sections of the several passages of the outlet baffle amounts to more than 40% of the flow cross section of the outlet passage. 
     Within the scope of the solution according to the invention, it is, however, also conceivable to provide one or several intermediate baffles in addition to the inlet baffle and to the outlet baffle. 
     In order to be able to position the damping element in an optimum manner with the solution according to the invention, it is preferably provided for the damping element to be fixed in position via an outer mounting element. 
     It is particularly favorable when one of the baffles is provided with flange areas serving as mounting element and can, therefore, be inserted in the cylinder head at the same time as the mounting flange for the damping element. 
     Additional features and advantages of the solution according to the invention are the subject matter of the following description as well as the drawings illustrating one embodiment. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1 : shows an exploded illustration of part of a compressor housing in the area of a cylinder head; 
         FIG. 2 : shows a view of a cylinder head illustrated in  FIG. 1  from its underside; 
         FIG. 3 : shows a section along line  3 - 3  in  FIG. 2 ; 
         FIG. 4 : shows a perspective illustration of a damping element according to the invention; 
         FIG. 5 : shows a section along line  5 - 5  in  FIG. 4 ; and 
         FIG. 6  shows a section along line  6 - 6  in  FIG. 4 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A compressor housing  10  of a displacement compressor designed according to the invention as a piston compressor and partially illustrated in  FIG. 1  comprises a cylinder housing  12  with a valve plate  14 , on which a cylinder head  18  is arranged which is sealed with a gasket  16  and forms via the valve plate  14  an inlet chamber  22  and an outlet chamber  24  which are separated from one another by a dividing wall  26  in the cylinder head  18 . 
     The cylinder head  18  is, in addition, provided with a short connection pipe  28  which is preferably arranged in a cover  30  of the cylinder head  18  and forms an outlet passage  32 , through which the compressed refrigerant can exit from the outlet chamber  24  and enter a pipe connection  34 . 
     The pipe connection  34  can be placed onto a connection surface  36  of the short connection pipe  28  and mounted on it. 
     In order to dampen pulsations in the flow of refrigerant exiting from the outlet chamber  24 , a damping element designated as a whole as  40 , which has, as illustrated in  FIGS. 1 to 6 , an inlet baffle  42  and an outlet baffle  44 , is inserted into the connection passage  32  in the short connection pipe  28  which is present in any case. 
     As a result, the use of the damping element  40  according to the invention does not lead to any increase in the space requirements in the compressor housing  10 . 
     The inlet baffle  42  comprises two passages  46   a  and  46   b  which are formed by pieces of pipe  48   a  and  48   b  which extend over a distance RE from entry openings  52   a  and  52   b  facing the outlet chamber  24  as far as first, inner openings  54   a  and  54   b  facing the outlet baffle  44 . 
     The two passages  46   a  and  46   b  are preferably arranged so as to be symmetric to a central axis  56  of the damping element  40 . Furthermore, the first, inner openings  54   a  and  54   b  are located at a distance AE from the outlet baffle  44  and each face a closed reflection surface  58   a  and  58   b  of the outlet baffle  44  formed by the outlet baffle  44  so that pulsation vibrations passing through the passages  46   a  and  46   b  first enter a chamber  50   a ,  50   b , which is limited by the outlet passage  32  and the outlet baffle  44 , with a jump in cross section at the first, inner openings  54   a ,  54   b  and then experience a reflection at the reflection surfaces  58   a  and  58   b  of the outlet baffle  44  and are thereby partially reflected back again through the passages  46   a  and  46   b  or are reflected into a chamber  60   a ,  60   b  which is located outside the pieces of pipe  48   a ,  48   b  and surrounds them and which is limited, on the one hand, by the outlet passage  32  of the short connection pipe  28  and, on the other hand, by the pieces of pipe  48   a  and  48   b  and by the inlet baffle  42  towards the outlet chamber  24 , namely by reflection surfaces  62   a  and  62   b  of the inlet baffle  42 . The reflection surfaces  58   a ,  58   b  and the reflection surfaces  62   a ,  62   b  have a distance BE from one another which is somewhat larger than RE plus AE. 
     Second, inner openings  64   a  and  64   b  of passages  66   a  and  66   b  arranged at a distance M from these reflection surfaces  62   a  and  62   b  are again associated with these reflection surfaces, located opposite them, so that a jump in cross section between the second, inner openings  64   a ,  64   b  and the reflection chambers  60   a ,  60   b  in relation to the passages  66   a ,  66   b  results, wherein the passages  66   a  and  66   b  are formed on the side of the outlet baffle  44 , namely by pieces of pipe  68   a  and  68   b  which extend from the outlet baffle  44  to the second, inner openings  64   a  and  64   b  and thereby proceed from outlet openings  70   a  and  70   b  in the outlet baffle  44  which are arranged at a distance RA from the inner openings  64   a ,  64   b , wherein the outlet openings  70   a  and  70   b  face the pipe connection  34  and so the compressed refrigerant exiting from them can flow away via the pipe connection  34 . 
     The passages  66   a  and  66   b  are also arranged symmetrically to the central axis  56  but offset through 90° in relation to the passages  46   a ,  46   b.    
     Furthermore, the second, inner openings  64  are arranged at a distance AA from the inlet baffle  42 . 
     In the case of the embodiment described, the distances AE between the inner openings  54   a  and  54   b  as well as the reflection surfaces  58   a  and  58   b  as well as the distances AA between the inner openings  64   a  and  64   b  and the reflection surfaces  62   a  and  62   b  are less than the lengths of the pieces of pipe  48   a  and  48   b  as well as  68   a  and  68   b  and so the pieces of pipe  48   a  and  48   b  overlap one another with their inner end areas  72   a  and  72   b  as well as  74   a  and  74   b . The pieces of pipe  48   a  and  48   b  as well as  68   a  and  68   b  are, therefore, connected to one another in the area of their inner ends  72   a  and  b  as well as  74   a  and  b  and so the pieces of pipe  48   a  and  48   b  as well as  68   a  and  68   b  keep the inlet baffle  42  and the outlet baffle  44  positioned at a distance from one another. 
     Furthermore, the outlet baffle  44  of the solution according to the invention is, as illustrated, in particular, in  FIGS. 1 and 4 , provided with flange areas  80  so that the outlet baffle  44  can be placed on the connection surface  36  with a seal  82  located therebetween while the pipe connection  34  can be placed in a sealed manner on the flange area  80  with an additional seal  84  which is located on the side of the flange areas  80  located opposite the seal  82 . 
     As a result, the damping element  40  according to the invention can be mounted in the outlet passage  32  in a simple manner, wherein the pieces of pipe  68   a  and  68   b  as well as  48   a  and  48   b  extend into the outlet passage  32  proceeding from the outlet baffle  44 , which is connected in one piece to the flange area  80 , and, therefore, hold the inlet baffle  42  in position in the outlet passage  32  in a defined manner. The inlet baffle  42  has such a diameter that it extends essentially over the cross section of the outlet passage  32  and so compressed refrigerant can enter the damping element  40  only via the entry openings  52 . 
     The damping element  40  according to the present invention acts in a pulsation damping manner, as a result, since pulsation waves, which normally occur at frequencies which correspond to higher harmonics of the basic frequency, are damped in it by way of reflection. 
     The prerequisite for stationary waves which extinguish one another in the pieces of pipe  48   a  and  48   b  is that the length RE of the pieces of pipe  48   a  and  48   b  must correspond to half the wavelength λ/2 of a harmonic of the basic frequency since reflections occur each time at open ends as a result of the entry openings  52   a  and  52   b  as well as the inner openings  54   a  and  54   b.    
     The prerequisite for stationary waves which extinguish one another between the inner openings  54   a  and  54   b  and the reflection surfaces  58   a  and  58   b  is that the length AE must correspond to a quarter wavelength λ/4 of a higher harmonic of the basic frequency since reflections occur at the open end as a result of the inner openings  54   a  and  54  and reflections occur at the closed end as a result of the reflection surfaces  58   a  and  58   b.    
     The prerequisite for stationary waves which extinguish one another between the reflection surfaces  58   a  and  58   b  as well as  62   a  and  62   b  is that the distance BE must correspond to half the wavelength λ/2 of the higher harmonic of the basic frequency since a reflection is present between closed ends. 
     Finally, the prerequisite AA=λ/4 of the higher harmonic of the basic frequency results for stationary waves which extinguish one another from the distances AA between the reflection surfaces  62   a  and  62   b  as well as the inner ends  64   a  and  64   b.    
     In addition, stationary waves which extinguish one another also occur when RA=λ/2 of the higher harmonic of the basic frequency. 
     Consequently, the damping element  40  is in a position to dampen a number of higher harmonics of the basic frequency, wherein the distances RE, BE and RA are selected such that their double value corresponds to one of the lowest harmonics of the basic frequency which occurs during the pulsations and wherein the distances AE and AA are selected such that their quadruple value corresponds to one of the lowest harmonics of the basic frequency, at which the pulsations occur. 
     In addition, the outlet chamber  24 , on the one hand, and the subsequent pipe  34 , on the other hand, also act as a chamber for the pulsation damping and so the damping element  40  itself does not require any chamber with a large volume and, therefore, allows a compact construction of the cylinder head  18 , in which the damping element  40  can be integrated in a simple manner since it must, for its part, merely deflect and reflect pulsation waves. 
     In this respect, the volume of the outlet chamber  24  is preferably selected to be of such a size that this corresponds at least to double, even better at least triple a piston capacity per cylinder of the piston compressor in order to obtain as favorable a damping effect as possible.