Patent Publication Number: US-2012024413-A1

Title: Three-way structure

Description:
CROSS REFERENCES TO RELATED APPLICATIONS 
     This application is a continuation in part of and claims priority from and benefit of China Application No. 201020274843.8, entitled “A THREE-WAY STRUCTURE,” filed on Jul. 27, 2010, which application is hereby incorporated by reference in its entirety. 
     TECHNICAL FIELD 
     The disclosure relates to a three-way structure for a variable frequency screw unit, particularly to a three-way structure that can effectively attenuate the exhaust noise of the variable frequency screw unit. 
     BACKGROUND 
     A three-way valve is generally used for conveying the flow of fluid, gas or other flowable substance, or for distributing single path flowable substance into multiple paths. For example, the refrigerant is distributed into two paths by a three-way valve in the chilling system of a variable frequency screw unit. 
       FIG. 1  illustrates the operating principle of a chilling system in a variable frequency screw unit. As shown in  FIG. 1 , the chilling system mainly includes a compressor  101 , a tee connection  102 , muffler  103 A and  103 B, oil separators  104 A and  104 B, a condenser  105 , a throttle valve  106  and an evaporator  107 . 
     In the variable frequency screw unit, the refrigerant gas with low temperature and low pressure is compressed into the gas with high temperature and high pressure by the compressor  101 , then distributed into two paths by means of the tee connection  102 , and subsequently transmitted to the oil separators  104 A and  104 B provided in the downstream via the muffler  103 A and  103 B which are used for reducing the pressure pulsation of the refrigerant and noise in the tubes respectively. The refrigerant with high temperature and high pressure is delivered to the condenser  105  via the oil separators  104 A and  104 B, so as to be condensed into liquid with high temperature and high pressure, and then throttled into liquid and vapor with low temperature and low pressure via the throttle valve  106 . The liquid with low temperature, low pressure is evaporated into gas with low temperature and low pressure by means of the evaporator  107 , and then delivered to the compressor  101 , so that a refrigeration cycle is completed in the entire chilling system. 
     The exhaust pipeline and the oil separators are the main downstream devices of the screw unit that radiate exhaust noise. The larger their diameters are, the lower rigidity their wall structure has, and thus the stronger the structural mode of vibration and noise generation becomes. The larger their diameters, the higher the noise radiation for the same excitation source. Furthermore, it will be more difficult to design an exhaust muffler located outside the compressor if the diameter of the exhaust pipeline becomes larger, particularly to design a muffler suitable for a variable frequency screw unit. Therefore, in order to avoid increasing the diameters of the exhaust pipeline and the oil separators, the exhaust fluid of the compressor is distributed by means of tee connection  102  to enable the exhaust pipeline and the oil separators to be configured with small diameters. Hence, a tee connection  102  is needed.  FIG. 2  is a section view of a tee connection in the prior art, wherein the port  201  is an inlet of the tee connection connected to the exhaust port of the compressor upstream, and the ports  202  and  203  are outlets of the tee connection connected to inlets of the mufflers downstream. 
     However, the design of the prior art structure makes the pipeline arrangement of the screw unit more difficult and additional pipeline connections need to be added between the tee connection and the mufflers, thereby increasing the noise radiation area and decreasing the efficiency of the muffler. 
     In view of this, it is necessary to solve the above problems and provide a structure that can both effectively utilize the exhaust muffler and simplify the pipeline arrangement of the unit. 
     SUMMARY 
     A series of simple descriptions are introduced in this section and will be further illustrated in detail in the mode of carrying out the intent of the disclosure. The contents of the disclosure are not intended to limit the critical features and the necessary technical features of the claimed technical solution, and are also not intended to restrict the protection scope of the claimed technical solution. 
     To solve the above technical problems, the disclosure discloses a three-way structure, including a straight tube ( 401 ) and a branch tube ( 402 ) perpendicular to and connected with the straight tube ( 401 ), characterized in that the inner surface of the straight tube ( 401 ) is provided with a hollow structure surrounding the straight tube. 
     In one embodiment, the diameters of ports ( 404 ,  405 ) of the straight tube ( 401 ) are smaller than that of the main body of the straight tube ( 401 ). 
     In a further embodiment, the hollow structure is provided symmetrically with respect to the branch tube ( 402 ). 
     In another embodiment, the hollow structure includes chambers ( 501 ,  502 ) mounted on both sides of the branch tube and are not connected with each other. 
     In one embodiment, the hollow structure includes chambers ( 601 ,  602 ,  603 ), which are not connected at the sides near the port of the branch tube, and are connected at the sides far from the port of the branch tube. 
     In a further embodiment, the chambers ( 501 ,  502 ;  601 ,  602 ,  603 ) are filled with sound absorption material. 
     In another embodiment, the sound absorption material is glass fiber. 
     In one embodiment, the hollow structure is a flow channel ( 701 ) vertically below the branch tube, and the flow channel ( 701 ) is provided with an opening ( 702 ) near the port of the branch tube, and the flow channel ( 701 ) is connected with the interior of the three-way structure through the opening ( 702 ). 
     In a further embodiment, the flow channel ( 701 ) has an annular structure. 
     In another embodiment, the interior of the straight tube includes first components ( 803 A,  803 B;  904 A,  904 B;  1003 A,  1003 B;  1204 ) hermetically connected to the inner wall of the straight tube by connecting pieces ( 804 A,  804 B;  905 A,  905 B;  1004 A,  1004 B;  1205 ); and the cross sectional area of the first components ( 803 A,  803 B;  904 A,  904 B;  1003 A,  1003 B;  1204 ) is smaller than that of the straight tube. 
     In one embodiment, the first components ( 803 A,  803 B;  904 A,  904 B;  1003 A,  1003 B) have frame structures. 
     In a further embodiment, the first components ( 803 A,  803 B;  904 A,  904 B;  1003 A,  1003 B) have annular frame structures. 
     In another embodiment, the three-way structure further includes a second component ( 1104 ) formed of sound absorptive material, the second component ( 1104 ) having an outer contour corresponding to the inner wall of the straight tube and a facing plate ( 1105 ) with porous structure, wherein through holes along the axial direction of the straight tube are disposed in the interior of the second component ( 1104 ), and the facing plate ( 1104 ) is in contact with the through holes. 
     In one embodiment, the sound absorptive material is melamine foam or sound absorption material coated with mylar and fibrous protecting layer. 
     In a further embodiment, the facing plate ( 1104 ) has a bottomless cylinder shape. 
     In another embodiment, the percentage of opening area of the facing plate ( 1104 ) is no less than 30%. 
     In one embodiment, the three-way structure further includes a first component ( 1204 ) and a connecting piece ( 1205 ) connecting the first component ( 1204 ) with the inner wall of the straight tube. 
     The three-way structure of the disclosure can both attenuate the noise and simplify the pipeline arrangement of the unit. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       The following Figures of the disclosure are part of content of the disclosure and used for understanding the disclosure. The examples of the disclosure are shown in the Figures for illustrating the principle of the disclosure, in which: 
         FIG. 1  illustrates the operation principle of a chilling system in a variable frequency screw unit; 
         FIG. 2  is a section view of a tee connection in the prior art; 
         FIG. 3  is a schematic view of a chilling system having a three-way structure of noise attenuation according to the disclosure; 
         FIG. 4  is a perspective view of the three-way structure of noise attenuation according to the disclosure; 
         FIG. 5  is a section view of a first embodiment of a three-way structure of reactive noise attenuation according to the disclosure; 
         FIG. 6  is a section view of a second embodiment of the three-way structure of reactive noise attenuation according to the disclosure; 
         FIGS. 7A and 7B  are section views of a third embodiment of the three-way structure of reactive noise attenuation according to the disclosure; 
         FIG. 8  is a section view of a fourth embodiment of the three-way structure of reactive noise attenuation according to the disclosure; 
         FIG. 9  is a section view of a fifth embodiment of the three-way structure of reactive noise attenuation according to the disclosure; 
         FIG. 10  is a section view of a sixth embodiment of the three-way structure of reactive noise attenuation according to the disclosure; 
         FIG. 11A  is a section view of a first embodiment of a three-way structure of resistance noise attenuation according to the disclosure; 
         FIG. 11B  is an exploded schematic view of the three-way structure of absorptive noise attenuation shown in  FIG. 11A ; 
         FIG. 12  is a schematic view of a three-way structure of reactive &amp; absorptive noise attenuation according to the disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     In the following description, details are provided for better understanding the disclosure. However, it is apparent for those skilled in the art that the disclosure can be implemented without one or more of the details. In other embodiments, some technical features well known in the art are not described to avoid being confused with the disclosure. 
     In order to effectively utilize the exhaust muffler, maximize the attenuation of the exhaust noise and simplify the pipeline arrangement of the unit, the disclosure provides a tee connection with noise attenuation function (called a three-way structure of noise attenuation hereinbelow).  FIG. 3  is a schematic view of a system having a three-way structure of noise attenuation according to the disclosure. As shown in  FIG. 3 , the system mainly includes a compressor  301 , a three-way structure of noise elimination  302 , oil separators  303 A, and  303 B, a condenser  304 , a throttle valve  305  and an evaporator  306 . A muffler and a tee connection are integrated together by means of the three-way structure of noise attenuation according to the disclosure, so as to simplify the pipeline arrangement of the unit. 
       FIG. 4  is a perspective view of a three-way structure of noise attenuation according to the disclosure. As shown in  FIG. 4 , the three-way structure of noise attenuation includes a straight tube  401  and a branch tube  402  perpendicular to and connected with the straight tube  401 . When the three-way structure is applied to the system shown in  FIG. 3 , port  403  of the branch tube  402  is an inlet of the three-way structure of noise attenuation; ports  404  and  405  of the straight tube  401  are outlets of the three-way structure of noise attenuation. Preferably, the diameter of the port of the straight tube is smaller that of the main body of the straight tube  401 . In this way, an exhaust pipeline and oil separator with smaller diameter can be connected at the outlets, so that their wall structure has better rigidity, which can effectively attenuate the noise radiation. 
     Sound energy radiated by the muffler can be attenuated by means of alteration that change the impedance during transmission of the sound, such as altering the section of the tube or bypassing a resonator, so as to produce the reflecting and interaction of the sound energy, so that the noise is attenuated. Therefore, the three-way structure applying the above noise attenuation principle to achieve the noise attenuation function is called a three-way structure of reactive noise attenuation. In order to attenuate the noise radiation of the three-way structure itself, the inner surface of the straight tube is provided with a hollow structure surrounding the straight tube. In one embodiment, the hollow structure is provided symmetrically with respect to the branch tube, so as to interchangeably use two ports of the straight tube during the mounting of the three-way structure of noise attenuation. Additionally, the symmetrical design is also suitable for industrial manufacture. 
     The hollow structure can include chambers with a hermetic structure not in contact with the fluid in the three-way structure, and the chambers can be filled with sound absorption material to effectively attenuate the noise radiation. The hollow structure can define a flow channel when it is a structure in communication with the interior of the three-way structure. 
     The three-way structure of reactive noise attenuation according to the disclosure will be described in detail in conjunction with the following specific examples.  FIGS. 5 to 7  show several positions of the hollow structure according to some exemplary embodiments of the disclosure. 
     Example 1 
     As shown in  FIG. 5 , the inner surface of the straight tube is provided with a hollow structure surrounding the straight tube at both sides of the branch tube, i.e. chambers  501  and  502 , which are not in contact with the fluid in the three-way structure. The chambers  501  and  502  are not connected with each other, and are symmetrically disposed at both sides of the branch tube. The chambers  501  and  502  are filled with sound absorption material having good sound absorption characteristic. For example, the sound absorption material is glass fiber. 
     Example 2 
     As shown in  FIG. 6 , chambers  601  and  602  that are not in contact with the fluid in the three-way structure are not connected at the side near the port of the branch tube, but are connected at the side far from the branch tube via chamber  603 . The chambers  601  and  602  are symmetrically provided at both sides of the branch tube, and the chambers  601  and  602  are in communication with chamber  603  respectively. The chambers  601 ,  602  and  603  are filled with sound absorption material having good sound absorption characteristic. For example, the sound absorption material is glass fiber. 
     Example 3 
     As shown in  FIG. 7A , the inner surface of the straight tube is provided with a hollow structure surrounding the straight tube, i.e. a flow channel  701 . The flow channel  701  is vertically below the branch tube, and the flow channel  701  is provided with an opening  702  near the port of the branch tube, and the flow channel  701  is in communication with the interior of the entire three-way structure of noise attenuation via the opening  702 . As further shown, the flow channel  701  has an annular structure.  FIG. 7B  is a cross section view of the straight tube in the three-way structure of noise attenuation shown in  FIG. 7A . As compared with the embodiments shown in  FIGS. 5 and 6 , the flow channel  701  is in communication with the interior of the entire three-way structure of noise attenuation, thereby having the function of reducing the noise to some extent. 
     Furthermore, in order to attenuate the exhaust noise, a first component is provided in the interior of the straight tube, the first component is hermetically connected with the inner wall of the straight tube through connecting pieces, and the cross section area of the first component is smaller than that of the straight tube. 
     The three-way structure of reactive noise attenuation according to the disclosure will be described in detail in conjunction with the following exemplary embodiments. The three-way structure of reactive noise attenuation shown in  FIGS. 8 to 10  is obtained by further adding additional components to the three-way structure of noise attenuation shown in  FIGS. 5 to 7 . 
     Example 4 
     As shown in  FIG. 8 , added components  803 A and  803 B are provided between the ports of the straight tube and the chambers  801 ,  802  in the interior of the straight tube. The components  803 A and  803 B are connected with the inner wall of the straight tube through connecting pieces  804 A and  804 B respectively, so that the fluid flows through the components  803 A and  803 B, thereby achieving the object of noise attenuation due to the change of the impedance as the fluid flows through the straight tube. As further shown, the components  803 A and  803 B are symmetrically provided at both sides of the branch tube. The components can be implemented as a frame structure, which can be polygon shape, annular shape and irregular shape etc. In one embodiment, the first components  803 A and  803 B have a frame structure with an annular shape. 
     Example 5 
     As shown in  FIG. 9 , added components  904 A and  904 B are provided between the ports of the straight tube and the chambers  901 ,  902 ,  903  in the interior of the straight tube. The components  904 A and  904 B are connected with the inner wall of the straight tube through connecting pieces  905 A and  905 B respectively, so that the fluid flows through the first components  904 A and  904 B, thereby achieving the object of noise attenuation as due to the change of the impedance as the fluid flows through the straight tube. As further shown, the components  904 A and  904 B are symmetrically provided at both sides of the branch tube. The shape and structure of the components  904 A and  904 B are similar to those shown in  FIG. 8 , and hence the details are omitted herein. 
     Example 6 
     As shown in  FIG. 10 , added components  1003 A and  1003 B are provided between the ports of the straight tube and the flow channel  1001  in the interior of the straight tube. The components  1003 A and  1003 B are connected with the inner wall of the straight tube through connecting pieces  1004 A and  1004 B respectively, so that the fluid flows through the first components  1003 A and  1003 B, thereby achieving the object of noise attenuation due to the change of the impedance as the fluid flows through the straight tube. As further shown, the components  1003 A and  1003 B are symmetrically provided at both sides of the branch tube. The shape and structure of the components  1003 A and  1003 B are similar to those shown in  FIG. 8 , and hence the details are omitted herein. 
       FIGS. 8 to 10  illustrate only three exemplary embodiments, and the three-way structure of noise attenuation according to the disclosure is not limited to the above three examples. The protection scope of the disclosure encompasses the cases where the added component is one or at least two. When there is a plurality of the added components, the added components in the same three-way structure of noise attenuation can be implemented to have different shapes and structures. Additionally, when there is a plurality of the added components, the added components can be disposed at the same side of the branch tube, or at both sides of the branch tube. When a plurality of added components are disposed at both sides of the branch tube, the disclosure encompasses the case where the added components are not symmetrical with respect to the branch tube. The added components can be formed integrally with the connecting pieces. 
     Optionally, in order to attenuate exhaust noise, a second component and a facing plate are provided in the interior of the straight tube. The second component is formed of sound absorption material and has outer contour corresponding to the inner wall of the straight tube; through holes are disposed along the axial direction of the straight tube in the interior of the second component; the facing plate has a porous structure and is in contact with the through holes. The noise attenuation principle of the above structure is that the sound absorption material absorbs the sound energy and converts it into heat energy or other forms of energy. Therefore, the three-way structure of noise attenuation having the above structure is called the three-way structure of absorptive noise attenuation. 
     Example 7 
     The three-way structure of absorptive noise attenuation according to the disclosure will be described in conjunction with the following exemplary embodiments. The three-way structure of absorptive noise attenuation shown in  FIGS. 11A and 11B  is obtained by further adding second components into the three-way structure of noise attenuation shown in  FIG. 6 .  FIG. 11A  is a section view of a three-way structure of absorptive noise attenuation according to the disclosure;  FIG. 11B  is an exploded schematic view of the three-way structure of absorptive noise attenuation according to the disclosure. 
     As shown in  FIG. 11A , a second component  1104  is provided between the port of the straight tube and the chambers  1101 ,  1102 ,  1103 . The second component  1104  is formed of sound absorption material having high chemical stability with respect to the fluid and good sound absorption characteristics, such as melamine foam or sound absorption material coated with mylar and fibrous protecting layer and the like. The second component  1104  has an outer contour corresponding to the inner wall of the straight tube, and through passages are disposed along the axial direction of the straight tube in the interior of the second component, fluid flowing through via the passages. Additionally, in order to protect the second component  1104  from being damaged as a result of the scouring of the high speed fluid, a facing plate  1105  is mounted on the surface of the second component  1104  containing the through passages. The facing plate has a porous structure. 
     As further shown in  FIG. 11A , the through passages provided in the middle of the second component  1104  have a cylinder structure, and the facing plate  1105  has an open cylinder shape. Apertures are disposed throughout the cylinder (as shown in  FIG. 11B ); the facing plate  1105  is generally formed of steel. The facing plate ( 1105 ) has a percentage of opening area of no less than 30%, wherein the percentage of opening area is a ratio of the sum of area of the apertures in the facing plate to the overall area of the facing plate. 
     The above example only illustrates the three-way structure of noise attenuation obtained for example by further adding a second component to the three-way structure of noise attenuation shown in  FIG. 6 . The protection scope of the disclosure encompasses all the modifications made to the three-way structure with chambers according to the disclosure. 
     Additionally, the disclosure provides a three-way structure of compound noise attenuation, which combines the characteristics of the reactive noise attenuation and the absorptive noise attenuation. The three-way structure of compound noise attenuation includes a first component and a second component, wherein the first component is connected with the inner wall of the straight tube through connecting pieces, and the second component has a facing plate. The three-way structure of reactive &amp; absorptive noise attenuation combines the characteristics of the reactive noise attenuation and the absorptive noise attenuation, including both the first component and the second component, so that the three-way structure can be used for an extended frequency range of the noise to be attenuated. 
     Example 8 
       FIG. 12  is a schematic view of a three-way structure of reactive &amp; absorptive noise attenuation according to the disclosure. As shown in  FIG. 12 , a first component  1204  and a second component  1205 , such as a connecting piece, are provided in the area on each side of the chambers  1201 ,  1202 ,  1203  and the port of the straight tube. The first component  1204  is connected to the inner wall of the straight tube through the connecting piece  1205 , with an outer surface of a second component  1206  positioned adjacent to the inner surface of the straight tube, the second component having a facing plate  1207  that can be configured to be supported by the first component  1204  or second component  1104  ( FIG. 11A ). As further shown in  FIG. 12 , the first component  1204  and the second component  1206  are symmetrically disposed at both sides of the branch tube, so that the same efficiency of noise attenuation is obtained in various directions, and the three-way structure of noise attenuation has no directivity. 
     The above preferable embodiments are only illustrative, and the disclosure also encompasses the case where at least one first component and at least one second component are not symmetrically disposed at both sides of the branch tube. The asymmetry includes that at least one first component and at least one second component are disposed at both sides of the branch tube with asymmetrical positions and asymmetrical numbers. 
     Comparison of the sound transmission loss between the three-way structure of reactive, absorptive and reactive &amp; absorptive noise attenuation, and comparison of the sound transmission loss between the above preferable three-way structure of reactive noise attenuation with three different inner configurations is also made. For example, if the inlet and outlet of the three-way structure of noise attenuation are 5 inch (127 mm) and 3 inch (76.2 mm) diameter respectively, the noise attenuation characteristic of the three-way structure of reactive noise attenuation has a good performance in a specific frequency range. The noise attenuation frequency band of the three-way structure of reactive noise attenuation with three different inner configurations is mainly in 400-900 Hz. Compared with the three-way structure of reactive noise attenuation, the three-way structure of absorptive noise attenuation has a broader noise attenuation frequency band, and has a more smooth transmission loss curve, but has low noise attenuation characteristic in some frequency range. The three-way structure of reactive &amp; absorptive noise attenuation has the combined characters of both the reactive noise attenuation and the absorptive noise attenuation. 
     Although the disclosure has been described by means of the above examples, it should be understood that the above examples are only for the purpose of illustration and are not intended to limit the disclosure. Additionally, it should be understood by those skilled in the art that the disclosure is not limited to the above examples, numerous variations and moderations can be made according to the teaching of the disclosure, which all fall into the scope claimed by the disclosure. The protection scope is defined by the appended claim set and its equivalents.