Abstract:
Disclosed herewith is a compressor with mufflers. The compressor comprises a drive unit, a compression unit, at least a pair of exhaust mufflers, a coolant exhaust conduit, and a connecting conduit. The drive unit generates power. The compression unit sucks, compresses and exhausts coolant using power transmitted from the drive unit. The exhaust mufflers temporarily store coolant exhausted from the compressing unit. The coolant exhaust conduit is connected to one of the exhaust mufflers to guide the exhaust of coolant to the outside. The connecting conduit connects the exhaust mufflers to each other to cancel out noises during the recombination of divided coolant in one of the exhaust mufflers.

Description:
CLAIM OF PRIORITY  
         [0001]    This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. §119 from an application for Compressor with Discharge Muffler earlier filed in the Korean Industrial Office on Dec. 11, 2000 and there duly assigned Serial No. 75129/2000 by that Office.  
         BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    The present invention relates generally to compressors used for refrigerators or the like, and more particularly to a compressor that is provided with a plurality of exhaust mufflers to reduce pressure pulsation generated during the exhaust of coolant.  
           [0004]    2. Description of the Prior Art  
           [0005]    In general, a compressor is an apparatus, which is applied to the refrigeration cycle of a refrigerator or the like (in which coolant undergoes a compression process, a condensing process, an expansion process and an evaporation process, sequentially), and compresses low-temperature and low-pressure coolant into high-temperature and high-pressure coolant. Such a compressor may be classified into a linear compressor or reciprocating compressor according to its operating movement.  
           [0006]    A conventional reciprocating compressor is comprised of a sealed container for constituting the outside of the compressor, a drive unit mounted in the sealed container for generating power, and a compression unit for sucking, compressing and exhausting coolant using power generated by the drive unit.  
           [0007]    The drive unit is mounted in the upper portion of the interior of the sealed container. The drive unit is comprised of a stator, a rotor, and a rotating shaft having an eccentric portion at its lower end. The rotating shaft is forcibly inserted into the center portion of the rotor, thus being rotated, together with the rotor.  
           [0008]    The compression unit is disposed in the lower portion of the interior of the sealed container. The compression unit is comprised of a cylinder head provided with suction and exhaust chambers for guiding the suction and exhaust of coolant, a cylinder block assembled with the cylinder head at its front end and provided with a compression chamber, a piston reciprocated through the compression chamber, and a connecting rod connected to the piston through an eccentric shaft for converting rotating movement into linear movement.  
           [0009]    In addition, a suction muffler is situated just over the cylinder head to reduce noise generated during the inflow of coolant. A coolant suction conduit is connected to the suction muffler. Two exhaust mufflers are mounted at two positions under the cylinder block to be connected to the exhaust chamber so as to reduce pressure pulsation generated during the exhaust of high-pressure coolant. A coolant exhaust conduit is connected to one of the exhaust mufflers. One exhaust muffler connected to the coolant exhaust conduit is constructed in a space expansion type, while the other exhaust muffler not connected to the coolant exhaust conduit is constructed in a Helmholtz resonator type.  
           [0010]    When the conventional reciprocating compressor constructed as described above is powered on, the rotating shaft is rotated together with the rotor, and the piston connected to the eccentric portion through the connecting rod is reciprocated through the compression chamber. Accordingly, coolant passes through the suction muffler and the suction chamber of the cylinder head, and flows into and is compressed in the compression chamber. Continuously compressed coolant is exhausted to the exhaust chamber of the cylinder head and the exhaust muffler.  
           [0011]    Low-pressure coolant sucked by the movement of the piston toward the bottom dead center is compressed by the movement of the piston toward the top dead center, and compressed coolant is exhausted to the exhaust chamber of the cylinder head. A portion of compressed coolant is sent to the space expansion type exhaust muffler and the remaining portion is sent to the Helmholtz type exhaust muffler, so the pressure pulsation of coolant is reduced. In this case, owing to the pressure difference during the movement of the piston toward its bottom dead center, compressed coolant in the Helmholtz resonance type muffler passes through the exhaust chamber of the cylinder head, enters the space expansion type exhaust muffler, and thereafter is exhausted to the outside.  
           [0012]    However, in the conventional reciprocating compressor, compressed coolant in the Helmholtz resonance type exhaust muffler passes through the exhaust chamber of the cylinder bead and enters the space expansion type exhaust muffler, so the peak of pressure pulsation is changed during the recombination of coolant, resulting in the problem of creating a noise having a different frequency band.  
           [0013]    Additionally, many factors, such as the volume of the exhaust muffler affecting the natural frequency of the Helmholtz resonance type exhaust muffler and the length and sectional area of the coolant passage connecting the exhaust chamber and the exhaust muffler, should be taken into account so as to reduce a noise generated in the exhaust chamber of the cylinder head, thus making the adjustment of the factors difficult to achieve.  
         SUMMARY OF THE INVENTION  
         [0014]    Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a compressor with mufflers, which is capable of considerably reducing the exhaust noises of coolant in such a way that noises created in the exhaust mufflers by pressure pulsation are cancelled out by destructive interference during the recombination of coolant by directly connecting the exhausting mufflers to one another.  
           [0015]    In order to accomplish the above object, the present invention provides a compressor, comprising: a drive unit for generating power; a compression unit for sucking, compressing and exhausting coolant by power transmitted from the drive unit; at least a pair of exhaust mufflers in which coolant exhausted from the compressing unit is temporarily stored; a coolant exhaust conduit connected to one of the exhaust mufflers to guide the exhaust of coolant to the outside; and a connecting conduit connecting the exhaust mufflers to each other to cancel out noises during the recombination of divided coolant in one of the exhaust mufflers.  
           [0016]    The connecting conduit is preferably constructed to have a length such that a first noise in a first exhaust muffler of the exhaust mufflers is allowed to be opposite in phase to a second noise in a second exhaust muffler after being transmitted to the second exhaust muffler.  
           [0017]    Under the conditions that the frequency bands of the noises generated in the exhaust mufflers are 350 to 600 Hz and the transmission speed of a noise in coolant is 161 m/s, the connecting conduit preferably has a length ranging from 13.4 to 23 cm.  
           [0018]    In addition, the present invention provides a compressor, comprising: a drive unit for generating power; a compression unit for sucking, compressing and exhausting coolant utilizing power transmitted from the drive unit; at least a pair of exhaust mufflers in which coolant exhausted from the compressing unit is temporarily stored; a coolant exhaust conduit connected to one of the exhaust mufflers to guide the exhaust of coolant to the outside; at least a pair of coolant passages each connecting the compression unit to each of the exhaust mufflers, the coolant passages having different lengths so that noises of coolant have opposite phases after the coolant passes through the coolant passages; and a connecting conduit connecting the exhaust mufflers to each other to cancel out the noises having opposite phases during the recombination of divided coolant in one of the exhaust mufflers. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0019]    The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:  
         [0020]    [0020]FIG. 1 is a partial cross-section showing a compressor with mufflers in accordance with an embodiment of the present invention;  
         [0021]    [0021]FIG. 2 is a cross-section taken along line II-II of FIG. 1;  
         [0022]    [0022]FIG. 3 is a cross-section taken along line III-III of FIG. 2;  
         [0023]    [0023]FIG. 4 is a diagram showing the operation of the compressor of the present invention in which the exhaust noises of coolant are reduced; and  
         [0024]    [0024]FIG. 5 is a bottom view showing another compressor with mufflers in accordance with another embodiment of the present invention. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0025]    Reference now should be made to the drawings, in which the same reference numerals are used throughout the different drawings to designate the same or similar components.  
         [0026]    A reciprocating compressor in accordance with the present invention is comprised of a sealed container  10  for containing oil in the lower portion of its interior, a drive unit  20  for generating power by the application of electricity, and a compression unit  30  for sucking, compressing and exhausting coolant using power generated by the drive unit  20 .  
         [0027]    The sealed container  10  constitutes the exterior of the reciprocating compressor, and is fabricated by airtightly attaching an upper container part  11  and the lower container part  12  to each other.  
         [0028]    The drive unit  20  is mounted in the upper portion of the interior of the sealed container  10 . The drive unit  20  is comprised of a stator  21  for generating a magnetic field by the application of electricity, a rotor  22  rotatably mounted in the stator  21 , and a rotating shaft  23  forcibly fitted into the rotor and provided with an eccentric portion at its lower end.  
         [0029]    The compression unit  30  is disposed in the lower portion of the interior of the sealed container  10 . The compression unit  30  is comprised of a cylinder block  31  provided with a compression chamber  31  a to suck, compress and exhaust coolant by the reciprocating movement of a piston  33 , a connecting rod  34  connecting the piston  33  and the eccentric portion  24 , a cylinder head  32  situated in front of the cylinder block  31  and provided with a sucking chamber  32   a  and the exhaust chamber  32   b . Reference numeral “ 25 ” designates a support bearing that is rested on the cylinder block  31  to support the rotation of the rotating shaft  23  and the rotor  22 . Reference numeral “ 40 ” designates a suction muffler that is situated over the cylinder head  32  to reduce noise generated by the inflow of coolant. A coolant suction conduit  13  is connected to the suction muffler  40  to guide coolant from the outside to the sealed container  10 .  
         [0030]    The exhaust mufflers  50 L and  50 R are provided under the cylinder block  31  so as to reduce pressure pulsation during the exhaust of compressed coolant through the exhaust chamber  32   b  of the cylinder head  32 . The detailed structure of the exhaust mufflers  50 L and  50 R will be described with reference to FIGS. 2 and 3.  
         [0031]    First of all, the exhaust mufflers  50 L and  50 R are symmetrically arranged under the cylinder block  31  at two positions, and secured to the cylinder block  31  by means of bolts. A damping space  51  is formed in the interior of each of the exhaust mufflers  50 L and  50 R.  
         [0032]    Coolant passages  52 L and  52 R are each formed in the cylinder block  31  to connect the exhaust chamber  32   b  (refer to FIG. 1) of the cylinder head  32  and each of the exhaust mufflers  50 L and  50 R. A coolant exhaust conduit  14  is connected to one of the exhaust mufflers  50 L and  50 R to exhaust coolant to the outside, that is, the refrigerating cycle (in this embodiment, as shown in FIG. 3, the coolant exhaust conduit  14  is connected to the right exhaust muffler  50 R).  
         [0033]    A connecting conduit  60  connects the exhaust mufflers  50 L and  50 R to each other so as to diminish noises by destructive interference during the recombination of the coolant. As a result, one end  61  of the connecting conduit  60  is connected to the left exhaust muffler  50 L and the other end  62  of the connecting conduit  60  is connected to the right exhaust muffler  50 R, so the two exhaust mufflers  50 L and  50 R communicate with each other by the connecting conduit  60 .  
         [0034]    In this case, the connecting conduit  60  should be constructed to have a length, which allows a noise in the left exhaust muffler  50 L to be opposite in phase to a noise in the right exhaust muffler  50 R.  
         [0035]    The determination of the length of the connecting conduit  60  will be described hereinafter.  
         [0036]    In order to allow the noise in the left exhaust muffler  50 L to be opposite in phase to the noise in the right exhaust muffler  50 R after passing through the connecting conduit  60 , the length of the connecting conduit  60  should satisfy the following equation:  
           L=λ/ 2  
         [0037]    where L is the length of the connecting conduit  60 , λ is c/f, c is the frequency of a noise, and f is the transmission speed of a noise in coolant.  
         [0038]    By way of example, under the conditions that the frequency “c” of the noises generated in the exhaust mufflers  50 L and  5 OR are 350 to 600 Hz and the transmission speed “f” of a noise in coolant R 134   a  generally applied to a refrigerator is 161 m/s (at 100° C.), the length L of the connecting conduit  60  is preferably 13.4 to 23 cm.  
         [0039]    As a result, after the noise in the left exhaust muffler  50 L is transmitted to the right exhaust muffler  50 R through the connecting conduit  60 , the phase of the noise from the left exhaust muffler  50 L becomes opposite to that of the noise in the right exhaust muffler  50 R. This causes the noise in the left exhaust muffler  50 L to cancel out the noise in the right exhaust muffler  50 R by destructive interference.  
         [0040]    In the reciprocating compressor, a noise having a certain frequency band can be easily eliminated by varying the length L of the connecting conduit  60 . Additionally, it is apparent that if the inner diameter of the connecting conduit  60  as well as the length L of the connecting conduit  60  is suitably adjusted, a noise having a certain frequency band can be easily eliminated.  
         [0041]    Hereinafter, the operation and effects of the reciprocating compressor of the present invention are described in detail.  
         [0042]    When the reciprocating compressor of the present invention is powered on, the rotor  22  is rotated with the rotating shaft  23  at a high speed. This rotating movement is converted into the linear movement of the piston  33  through the connecting rod  33 .  
         [0043]    Accordingly, the piston  33  is reciprocated through the compression chamber  31   a . When the piston  33  is moved toward its bottom dead center, or is at its suction stage, low-pressure coolant is sucked to the compression chamber  31   a  through the suction muffler  40  and the suction chamber  32   a ; whereas the piston  33  is moved toward its top dead center, or is at its exhaust stage, compressed coolant is exhausted to the exhaust chamber  32   b  and the damping spaces of the exhaust mufflers  50 L and  50 R and continues to be exhausted out of the sealed container  10  through the coolant exhaust conduit  14 . This operation is performed one time for a single revolution of the rotating shaft  23 .  
         [0044]    In the meantime, a portion of compressed coolant exhausted to the exhaust chamber  32   b  is sent to the left exhaust muffler  50 L through the left coolant passage  52 L and the remaining portion is sent to the right exhaust muffler  50 R through the right coolant passage  52 R, so pressure pulsation is reduced. In this state, coolant is exhausted to the outside through the coolant exhaust conduit  14 . The compressed coolant sent to the left exhaust muffler  50 L is exhausted to the right exhaust muffler  50 R through the connecting conduit  60 . During this process, the noises of the compressed coolant are cancelled out.  
         [0045]    As shown in FIG. 4, a first noise “A” having a sine wave is created while compressed coolant is exhausted to the exhaust chamber  32   b  (refer to FIG. 1) of the cylinder head  32 , and  18  the first noise “A” of a certain frequency band created by pressure pulsation is transmitted to the left and right exhaust mufflers  50 L and  50 R while the compressed coolant is sent to the left and right exhaust mufflers  50 L and  50 R. In other words, while the compressed coolant is sent to the left and right exhaust mufflers  50 L and  50 R, the second and third noises “B” and “C”having the same frequency as that of the first noise are created.  
         [0046]    Thereafter, the compressed coolant sent to the right exhaust muffler  50 R is directly exhausted to the outside through the coolant exhaust conduit  14 ; while the compressed coolant sent to the left exhaust muffler  50 L is sent to the right exhaust muffler  50 R through the connecting conduit  60  and recombined with the compressed coolant remaining in the right exhaust muffler  50 R.  
         [0047]    While the noise “B” in the left exhaust muffler  50 L, together with the compressed coolant, is transmitted to the right muffler  50 R through the connecting conduit  60 , the noise “B” becomes a noise “D” that has a phase difference of 180° in comparison with the noise “C” in the right exhaust muffler  50 R.  
         [0048]    As a result, while the compressed coolant in the left exhaust muffler  50 L is recombined with the compressed coolant in the right exhaust muffler  50 R through the connecting conduit  60 , the noises are cancelled out by destructive interference. Consequently, the entire exhaust noise of the compressed coolant is considerably reduced.  
         [0049]    Meanwhile, although the noises are described as being canceled out by the adjustment of the length L of the connecting conduit  60 , the object of the present invention can be achieved by the adjustment of the lengths L 1  and L 2  of the coolant passages  52 L and  52 R that connect the exhaust chamber  32   b  (refer to FIG. 1) to the exhaust muffler  50 L and the exhaust chamber  32   b  (refer to FIG. 1) to the exhaust muffler  50 R, respectively.  
         [0050]    In more detail, in order to allow the phases of noises to be opposite after the compressed coolant is sent to the exhaust mufflers  50 L and  50 R through the coolant passages  52 L and  52 R, the length LI of the left coolant passage  52 L connecting the exhaust chamber  32   b  to the left exhaust muffler  50 L and the length L 2  of the right coolant passage  52 R connecting the exhaust chamber  32   b  to the right exhaust muffler  50 R are designed to be different from each other (in this embodiment, the length L 1  of the left coolant passage  52 L is designed to be longer than the length L 2  of the right coolant passage  52 R, that is, L 1 &gt;L 2 ).  
         [0051]    Accordingly, the noise generated during the exhaust of coolant from the exhaust chamber  32   b  of the cylinder head  32  is transmitted to the exhaust mufflers  50 L and  50 R through the coolant passages  52 L and  52 R of different lengths L 1  and L 2 , so the noises in the left and right mufflers have opposite phases.  
         [0052]    The compressed coolant sent to the left exhaust muffler  50 L is sent to the right exhaust muffler  50 R through the connecting conduit  60 , recombined with the coolant remaining in the right exhaust muffler  50 R, and discharged from the sealed container  10 , together with the coolant remaining in the right exhaust muffler  50 R. In this case, the noise in the left exhaust muffler  50 L, together with the compressed coolant, is transmitted to the right exhaust muffler  50 R through the connecting conduit  60 , so the noise transmitted from the left exhaust muffler  50 L and the noise in the right exhaust muffler  50 R are canceled out by destructive interference. Accordingly, the entire exhaust noises of the compressed coolant are considerably reduced.  
         [0053]    As described above, the present invention provides a compressor with exhaust mufflers in which a pair of exhaust mufflers is symmetrically arranged under its cylinder block, a coolant exhaust conduit is connected to one of the exhaust mufflers and the exhaust mufflers are connected by a connecting conduit to communicate with each other. In this case, the length of the connecting conduit is designed so as to allow the phase of the noise of coolant contained in one of the exhaust mufflers to be opposite to the phase of the noise of the coolant contained in the other exhaust muffler after the transmission of the noise of the former exhaust muffler. As a result, noises are cancelled out by destructive interference while the compressed coolant sent to a pair of exhaust mufflers are recombined with each other through the connecting conduit, so the entire noises of compressed coolant are considerably reduced. Additionally, a noise having any frequency band can be easily eliminated by varying the length of the connecting conduit.  
         [0054]    Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.