Patent Publication Number: US-2021180581-A1

Title: Vacuum pump exhaust pipe muffler and refrigerator having same

Description:
This application claims the priority of Chinese patent application, the filing date of which is Dec. 11, 2017, the application number is 201711311262.X, and the title of invention is “vacuum pump exhaust pipe muffler and refrigerator having same”, the entire contents of which are incorporated herein by reference in its entirety. 
     TECHNICAL FIELD 
     The present invention relates to the technical field of noise reduction of refrigeration apparatus, and specifically to a muffler for reducing noise of a vacuum pump. 
     BACKGROUND 
     Freshness of food in a refrigerator is closely related to temperature, humidity and gas environment, wherein oxygen is an important factor causing spoilage, deterioration and bacteria multiplication of the food. A preservation period of the food may be significantly prolonged by pumping oxygen in the compartment to control a nitrogen-to-oxygen ratio of the refrigerator. 
     Oxygen may be pumped out from a specific space via a vacuum pump, and discharged outside the refrigerator. However, when gas, as a medium for conducting a sound, conducts noise in the refrigerator to an external space of the refrigerator during the discharge, thereby causing noise interference. 
     SUMMARY 
     An object of the present invention is to provide a muffler to solve the problem of noise output of a vacuum pump. 
     To achieve the object, the present invention provides a muffler comprising a hollow cavity enclosed by a first bottom surface, a second bottom surface and a side wall, the side wall connects the first bottom surface with the second bottom surface; an air inlet at one end of the muffler and an air outlet at the other end of the muffler; the cavity is divided into a plurality of chambers in an axial direction, the chambers comprise a first chamber adjacent to the first bottom surface, a second chamber adjacent to the second bottom surface and an intermediate chamber located between the first chamber and the second chamber, the air inlet is in gas communication with the intermediate chamber, the intermediate chamber is in gas communication with the second chamber, the first chamber is in gas communication with the second chamber, and the air outlet is in gas communication with the first chamber. 
     A further improvement as an embodiment of the present invention, at least part of the chambers has different volumes. 
     A further improvement as an embodiment of the present invention, the muffler further comprises a first duct, a second duct, a third duct and a fourth duct, the first duct is communicated with the air inlet and the intermediate chamber, the second duct is communicated with the intermediate chamber and the second cavity, the third duct is communicated with the first chamber and the second chamber, and the fourth duct is communicated with the first chamber and the air outlet. 
     A further improvement as an embodiment of the present invention, the first duct, the second duct, the third duct and the fourth duct are configured to be arranged in turn in an air path direction. 
     A further improvement as an embodiment of the present invention, there is at least one the intermediate chamber. 
     To achieve the object, the present invention provides a muffler comprising a housing, wherein the housing is enclosed to form a hollow cavity, an air inlet is arranged at a proximal end of the housing, an air outlet is arranged at a distal end of the housing, the cavity is divided into a plurality of chambers from the proximal end to the distal end, the chambers comprise a first chamber positioned relatively adjacent to the proximal end, a second chamber positioned relatively adjacent to the distal end and an intermediate chamber located between the first chamber and the second chamber, the air inlet is in gas communication with the intermediate chamber, the intermediate chamber is in gas communication with the second chamber, the first chamber is in gas communication with the second chamber, and the air outlet is in gas communication with the first chamber. 
     A further improvement as an embodiment of the present invention, at least part of the chambers has different volumes. 
     A further improvement as an embodiment of the present invention, the muffler further comprises a first duct, a second duct, a third duct and a fourth duct, the first duct is communicated with the air inlet and the intermediate chamber, the second duct is communicated with the intermediate chamber and the second cavity, the third duct is communicated with the first chamber and the second chamber, and the fourth duct is communicated with the first chamber and the air outlet. 
     A further improvement as an embodiment of the present invention, the first duct, the second duct, the third duct and the fourth duct are configured to be arranged in turn in an air path direction. 
     To achieve the project, the present invention provides a refrigerator comprising a sealed box receiving a vacuum pump, wherein the refrigerator further comprises the muffler as above, and the vacuum pump is connected with the muffler. 
     As compared with the prior art, a refrigerator vacuum pump muffler provided by the present invention realizes the attenuation of sound waves by the design with multiple cavities and cyclically-arranged ducts, reduces the sound energy, and prevents the noise of the vacuum pump and a box from being conducted outside the box. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic structural diagram of a sealed box according to an embodiment of the present invention; 
         FIG. 2  is a schematic diagram of components inside and outside a sealed box according to an embodiment of the present invention; 
         FIG. 3  is a top view of a sealed box according to an embodiment of the present invention; 
         FIG. 4  is an exploded schematic view of a sealed box according to an embodiment of the present invention; 
         FIG. 5  is a front view of a sealed box according to an embodiment of the present invention; 
         FIG. 6  is a top view of a seal in an embodiment of the present invention; 
         FIG. 7  is a schematic structural diagram of a seal in an embodiment of the present invention; 
         FIG. 8  is a top view of a lower sealing body in an embodiment of the present invention; 
         FIG. 9  is a schematic diagram of mounting an upper sealing body and a metal plate in an embodiment of the present invention; 
         FIG. 10  is a schematic structural diagram of a lower sealing body in an embodiment of the present invention; 
         FIG. 11  is an exploded view of  FIG. 10 ; 
         FIG. 12  is a perspective view of a muffler in an embodiment of the present invention; 
         FIG. 13  is a perspective view of a muffler in another embodiment of the present invention; 
         FIG. 14  is a schematic structural diagram of a vacuum pump and a muffler in a further embodiment of the present invention; 
         FIG. 15  is a schematic structural diagram of a muffler in a further embodiment of the present invention; 
         FIG. 16  is a perspective view of a muffler in a further embodiment of the present invention; 
         FIG. 17  is a schematic longitudinal sectional view of a muffler in a further embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     The present invention will be described in detail in conjunction with specific embodiments shown in the figures. However, these embodiments are not limited to the present invention. Variations in terms of structure, method or function made by those having ordinary skill in the art according to these embodiments are all comprised in the scope of the present invention. 
     Terms indicating positions and directions described in the present invention all take a vacuum pump as a reference. An end close to the vacuum pump is a proximal end, and an end away from the vacuum pump is a distal end. 
     Referring to  FIG. 1  through  FIG. 3 , in an embodiment of the present invention, a vacuum pump  100  is received in a sealed box  200 , and communicated with ambient air through an air inlet pipe  210  and an air outlet pipe  220 . A proximal end of the air inlet pipe  210  is communicated with an air intake line of the vacuum pump  100 , and a distal end is communicated with a fresh-keeping space in the refrigerator compartment (not shown); a proximal end of the air outlet pipe  220  is communicated with an air exhaust line of the vacuum pump  100 , and a distal end extends towards outside the sealed box  200 . The sealed box  200  blocks air communication between the vacuum pump  100  and an installation environment, and achieves an effect of sound insulation. The fresh-keeping space may be either an independent compartment or a closed or semi-closed space located in a portion of the refrigerator compartment. 
     The sealed box  200  comprises an upper sealing body  230  and a lower sealing body  240 . The upper sealing body  230  comprises a top wall and side walls which are integrally formed and jointly define a receiving cavity with a lower end opening. The lower sealing body  240  comprises a bottom wall and side walls which are integrally formed and jointly define a receiving cavity with an upper end opening. The opening of the upper sealing body  230  and the opening of the lower sealing body  240  match each other, and snap fit each other to form a receiving space of the vacuum pump  100 . 
     Preferably, the upper sealing body  230  and the lower sealing body  240  are made of plastic. 
     Referring to  FIG. 4 , a seal is provided between the upper sealing body  230  and the lower sealing body  240 . A first groove is formed at a lower edge of the side walls of the upper sealing body  230 , a second groove is formed at an upper edge of the side walls of the lower sealing body  240 , and the first groove matches with the second groove to form a mounting groove for a gasket ring  250 . In this way, the airtightness can be ensured after the upper sealing body  230  and the lower sealing body  240  are snap fitted, and sound can be prevented from being transmitted outside through a splicing gap of the sealed box  200 . The gasket ring  250  is ring-shaped and has a circular cross-section. The gasket ring  250  is made of an elastic material, and has a mounting tension amount 2-5% when embedded in the mounting groove. When the upper sealing body  230  and the lower sealing body  240  are snap-fitted, a pressure is applied to the gasket ring  250  to form a 20-30% compression amount, thereby ensuring the sealing effect. 
       FIG. 4  and  FIG. 5  show that a notch portion  251  is provided at where the upper sealing body  230  and the lower sealing body  240  are engaged, and allows a wire connected to the vacuum pump  100  to pass through. In order to ensure the sealing performance of the sealed box  200 , a snap-fittable sealing ring  253  is provided at the notch portion  251 . The sealing ring  253  is made of an elastic material and integrally formed with the gasket ring  250 . 
     Referring to  FIG. 6  and  FIG. 7 , the sealing ring  253  is composed of two H-shaped members that are flexibly connected, and the H-shaped members can be snap-fitted to each other to form a mounted state that cooperates with the notch portion  251 . The H-shaped member has a first arm  2531  and a second arm  2532  parallel to each other, and a connecting portion  2533  connecting the first arm  2531  with the second arm  2532 . The first arm  2531  and the second arm  2532  can cooperate to clamp the side wall of the box body at the edge of the notch portion  251  therebetween to prevent the sealing ring  253  from falling off from the notch portion  251 . The connecting portion  2533  passes through the notch portion and connects the first arm  2531  with the second arm  2532 . The connecting portion  2533  has a recessed arc-shaped surface. When the H-shaped members are snap-fitted to each other, their arc-shaped surfaces together enclose to form a hollow cavity to allow the wire to pass therethrough. 
     In a case where a plurality of wires passes through the notch portion  251 , if the wires as a whole pass through the notch portion  251 , since the cross section of the wires is circular, a gap formed between the wires will reduce the sealing performance. In this case, the arc-shaped surface of the connecting portion  2533  may be wavy (not shown) to form a plurality of independent hollow cavities in the mounted state to better seal the wires with a circular cross-section. 
     Referring to  FIG. 8 , a plurality of metal plates  260  are disposed in the sealed box  200 , and the metal plates  260  are disposed between the vacuum pump  100  and the side walls of the sealed box  200 . Since the metal plates  260  have a high density, they can block transmission of sound therethrough and achieve an effect of sound insulation and noise reduction. 
     Preferably, the metal plate  260  is an aluminum plate, a steel plate, or a galvanized plate. 
     Referring to  FIG. 8  and  FIG. 9 , in an embodiment of the present invention, there are two metal plates  260  which are respectively attached to two opposite walls of the sealed box  200 . The lower sealing body  240  and the upper sealing body  230  are respectively provided with a limiting structure to secure the metal plates  260   a  and  260   b.    
       FIG. 8  shows that the bottom wall of the lower sealing body  240  is provided with a first rib  242  being parallel to a side wall  241  and spaced apart a distance d, and a second rib  244  being parallel to a side wall  243  and spaced apart a distance D, wherein the side wall  241  and the side wall  243  are opposed, d is the thickness of the metal plate  260   a , and D is the thickness of the metal plate  260   b . The spacing between the first rib  242  and the side wall  241  forms a limiting groove that limits the horizontal displacement of the metal plate  260   a , and the spacing between the second rib  244  and the side wall  243  forms a limiting groove that limits the horizontal displacement of the metal plate  260   b.    
     Referring to  FIG. 8  and  FIG. 10 , the lower sealing body  240  is further provided with a plurality of guide grooves  245 . The guide grooves  245  extend in a vertical direction and the extension direction is consistent with the insertion direction installing the metal plates  260 . The guide grooves  245  guide the metal plates  260  to be mounted to preset positions. 
       FIG. 9  shows that the upper sealing body  230  is provided with a plurality of resisting members  231 . When the upper sealing body  230  and the lower sealing body  240  are snap-fitted, the resisting member  231  against the top of the metal plate  260 . A stepped portion  2311  is provided at an end of the resisting member  231  which is in contact with the metal plate  260 . The stepped portion  2311  cooperates with the side walls of the upper sealing body  230  to form an inverted U-shaped space to accommodate the top of the metal plate  260 . The top surface of the stepped portion  2311  against the top surface of the metal plate  260  and limits the displacement of the metal plate  260  in the vertical direction. The sides of the stepped portion abut against the sides of the metal plate  260  and limit the displacement of the metal plate  260  in the horizontal direction. 
     The metal plate  260  is disposed close to the side wall of the sealed box  200 . The vibration of the vacuum pump  100  might cause resonance of the metal plate  260  to form new noise which is conducted externally through the walls of the sealed box  200 . The above limiting structures strictly limit the position of the metal plates  260  to avoid resonating and generating noise. 
     In an embodiment of the present invention, a notch portion  246  is disposed on one of the upper sealing body  230  and lower sealing body  240 , or on an engagement portion of the upper sealing body  230  and lower sealing body  240 , to allow an air pipe assembly to pass therethrough. 
       FIG. 10  and  FIG. 11  exemplarily show a case where the notch portion  246  is provided on the lower sealing body  240 . The notch portion  246  is provided on a side wall of the lower sealing body  240  close to the upper edge, and a groove is provided at peripheral edge of the notch portion  246  to receive a sealing unit  270  to ensure the airtightness of the sealed box  200 . The sealing unit  270  has an annular structure made of an elastic material. 
     The air pipe assembly comprises an air inlet pipe  210 , an air outlet pipe  220  and a base plate that are integrally formed. The air inlet pipe  210  and the air outlet pipe  220  are disposed through the base plate, and an outer edge of the base plate matches the shape of the notch portion  246 . A groove is provided on the outer edge of the base plate to mate with a flange on the periphery of the notch portion  246 , the mating of the groove and the flange can clamp and secure the base plate to the notch portion, and the sealing unit  270  is embedded at a gap between the groove and the flange. 
     The space of the cavity for receiving the vacuum pump  100  is compact and does not facilitate the operation of connecting and passing the air pipe line. It is possible to, by setting the air pipe assembly as an embedded mounting structure, conveniently embed and secure the air pipe assembly in the notch portion  246  after the air pipe assembly is connected with the vacuum pump  100 , and then snap-fit the upper sealing body  230  and the lower sealing body  240  to complete the assembling. 
     The gas from the air outlet pipe  220  is exhausted to the outside of the refrigerator after being silenced. Referring to  FIG. 1  and  FIG. 12 , in an embodiment of the present invention, the vacuum pump  100  is connected to the muffler  300  through the air outlet pipe  220 . The muffler  300  comprises a housing. The housing is enclosed jointly by a first bottom surface  310  at a proximal end, a second bottom surface  320  at a distal end and a side wall  330  connecting the first bottom surface  310  with the second bottom surface  320  to form a cylindrical hollow cavity. The muffler  300  is provided at the proximal end with an air inlet  340  connected to the air outlet pipe  220 , and provided with an air outlet  350  at the distal end. The interior of the cavity is divided into several chambers in an axial direction, the axial direction is the direction from the air inlet  340  to the air outlet  350 , and at least part of the chambers has different volumes to correspondingly remove sounds at different frequency bands. Exemplarily, the volumes of respective chambers gradually decrease in the axial direction. 
     Preferably, there are three chambers, which are a first chamber  361 , an intermediate chamber  362  and a second chamber  363  in turn from the proximal end to the distal end. The first chamber  361  is adjacent to the first bottom surface  310 , the second chamber  363  is adjacent to the second bottom surface  320 , and the intermediate cavity  362  is located between the first chamber  361  and the second chamber  363 . A first duct  371  is communicated with the air inlet  340  and the intermediate chamber  362 , a second duct  372  is communicated with the intermediate chamber  362  and the second chamber  363 , a third duct  373  is communicated with the first chamber  361  and the second chamber  363 , and a fourth duct  374  is communicated with the first chamber  361  and the air outlet  350 . 
     There may be a plurality of intermediate chambers  362 . 
     The shape of the housing of the muffler is not limited to a cylindrical shape, and may be set to a rectangular parallelepiped shape or an irregular shape. 
     Sound waves from the vacuum pump  100  pass through the first duct  371 , the second duct  372 , the third duct  373  and the fourth duct  374  in turn along with the airflow, and are reflected and refracted in turn in the intermediate chamber  362 , the second chamber  363  and the first chamber  361  which have different volumes, and their energy is gradually dissipated. The muffling frequencies corresponding to the first chamber  361 , the intermediate chamber  362  and the second chamber  363  are a low frequency, a medium frequency and a high frequency. In addition, the first duct  371 , the second duct  372 , the third duct  373  and the fourth duct  374  are provided with narrow inner diameters, so that partial energy of the sound waves is converted into thermal energy and dissipated when the sound waves pass through the ducts. 
     The muffler is arranged in a way that the sound waves travel in a path as long as possible in the muffler to reduce the energy and are reflected and refracted in different chambers, and a better muffling effect is achieved with a smaller muffler axial distance. 
     Referring to  FIG. 13 , in a further embodiment of the present invention, the muffler  400  comprises a housing. The housing is enclosed jointly by a first bottom surface  410  at a proximal end, a second bottom surface  420  at a distal end, and a side wall  430  connecting the first bottom surface  410  with the second bottom surface  420  to form a cylindrical hollow cavity. A single chamber is formed in the cavity. The muffler  400  is provided with an air inlet  440  connected to the air outlet pipe  220  at the proximal end, and an air outlet  450  provided at the distal end. A first duct  471  is communicated with the air inlet  440  and the chamber, and a distal end of the first duct  471  is adjacent to the second bottom surface  420 . A second duct  472  is communicated with the chamber and the air outlet  450 , and a proximal end of the second duct  472  is adjacent to the first bottom surface  420 . 
     The sound waves are reflected and refracted in the chamber, and the energy is gradually dissipated. The length of the first duct  471  and the second duct  472  is a quarter of a wavelength of a target audio to specifically eliminate the sound of the target audio. Preferably, a frequency of the target audio is 1000 Hz. 
     The first duct  471  and the second duct  472  are provided with narrow inner diameters, so that partial energy of the sound waves is converted into thermal energy and dissipated when the sound waves pass through the ducts. 
     In the noise generated by the vacuum pump  100  and conducted via gas, the high-frequency noise cannot be heard by human ears, and the noise causing interference to the user is mainly low-frequency noise. The present embodiment may purposefully eliminate low-frequency noise and make the structure of the muffler simpler. 
     Referring to  FIG. 14  and  FIG. 15 , in a further embodiment of the present invention, the muffler  500  is disposed inside the sealed box  200 , and connects the exhaust line of the vacuum pump  100  and the air outlet pipe  220 . The muffler  500  comprises a housing, and the housing is enclosed to form a hollow cavity for refraction and reflection of sound waves. The hollow cavity comprises a cylindrical chamber  510  and a rectangular parallelepiped chamber  520 . One of bottom surfaces of the cylindrical chamber  510  is connected to one surface  521  of the rectangular parallelepiped chamber  520 . The cylindrical chamber  510  is communicated with the interior of the rectangular parallelepiped chamber  520 . 
     The diameter of the bottom surface of the cylindrical chamber  510  is less than or equal to a length of a side of a connecting surface  521  of the rectangular parallelepiped chamber  520 . 
     The cylinder chamber  510  of the muffler  500  is provided with an air inlet  540  and an air outlet  550 , and the air inlet  540  and the air outlet  550  are arranged at an angle so that the gas entering the hollow cavity reaches the outlet through reflected and refracted. During the process, the energy loses to achieve the muffling purpose. 
     Preferably, the air inlet  540  is disposed on the bottom surface  511  of the cylindrical chamber  510 , and the air outlet  550  is disposed on a side of the cylindrical chamber  510 . 
     The inner diameters of the air inlet  540  and the air outlet  550  are the same, so that the pressures at the two ports are balanced. 
     In the present embodiment, through the change of the shape of the hollow cavity, the sound waves are enabled to be reflected and refracted irregularly, and the energy is dissipated. 
     Referring to  FIG. 16  and  FIG. 17 , in a further embodiment of the present invention, a muffler  600  comprises a housing, and the housing is enclosed to form a hollow cavity. The muffler  600  is provided with an air inlet  640  at a proximal end and an air outlet  650  at a distal end. The air inlet  640  and the air outlet  650  are communicated by a duct  670  provided in the housing. The duct  670  and the housing form a sleeve structure. The duct  670  is filled with a medium to absorb the vibrational energy of the sound waves and weaken the sound intensity. Furthermore, the medium is silencer cotton. 
     A plurality of through holes  680  are defined on the side wall of the duct  670 , so that the duct  670  can implement communication with the cavity. The through holes  680  are distributed spaced apart in a circumferential direction of the sidewall of the duct  670 , that is, the duct  670  defines through holes in a plurality of directions. 
     Preferably, the housing is enclosed jointly by a first bottom surface  610  at a proximal end, a second bottom surface  620  at a distal end, and a side wall  630  connecting the first bottom surface  610  with the second bottom surface  620  to form a cylindrical hollow cavity. The first bottom surface  610  is provided with an air inlet  640 , and the second bottom surface  620  is provided with an air outlet  640 . 
     Preferably, a diameter of the through holes is less than 1 mm. 
     Preferably, the cavity enclosed by the housing is divided into several chambers arranged from the proximal end to the distal end. 
     The sound waves from the vacuum pump  100  enter the duct  670  from the air inlet  640 , and reach the air outlet  650  after being silenced by the medium. The sound waves at a specific frequency are attenuated and the sound intensity is weakened. During this process, partial sound waves, being diffracted by the through holes  680 , enter the cavity, and are further attenuated after being refracted and reflected in the cavity. 
     The muffler is arranged in a way that the sound intensity is reduced through multiple channels by combining medium sound reduction with cavity sound reduction and be employing small holes to implement sound wave diffraction. 
     It should be understood that although the description is described according to the embodiments, not every embodiment only comprises one independent technical solution, that such a description manner is only for the sake of clarity, that those skilled in the art should take the description as an integral part, and that the technical solutions in the embodiments may be suitably combined to form other embodiments understandable by those skilled in the art. 
     The detailed descriptions set forth above are merely specific illustrations of feasible embodiments of the present invention, and are not intended to limit the scope of protection of the present invention. All equivalent embodiments or modifications that do not depart from the art spirit of the present invention should fall within the scope of protection of the present invention.