Patent Publication Number: US-2019195225-A1

Title: Rotary blower

Description:
TECHNICAL FIELD 
     The present application generally relates to blowers and more particularly, but not exclusively, to rotary blowers. 
     BACKGROUND 
     Rotary blowers of various types, e.g., Roots blowers, remain an area of interest. Some existing systems have various shortcomings, drawbacks and disadvantages relative to certain applications. For example, in some rotary blowers, undesirable amounts of leakage between the rotors and/or between the housing and the rotors may occur. Accordingly, there remains a need for further contributions in this area of technology. 
     SUMMARY 
     A rotary blower includes a housing and a pair of meshed rotors. The meshed rotors are disposed in the housing. Each rotor has a plurality of lobes. Each lobe includes a lobe tip seal insert mounted thereon. The lobe tip seal insert is disposed at a tip of each lobe. Each lobe tip seal insert is constructed to seal against the housing and to prevent or reduce leakage between each lobe and the housing. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       The description herein makes reference to the accompanying drawings wherein like reference numerals refer to like parts throughout the several views, and wherein: 
         FIG. 1  schematically illustrates a cross-sectional view depicting some aspects of a non-limiting example of a rotary blower in accordance with an embodiment of the present invention. 
         FIG. 2  schematically illustrates a cross-sectional view depicting some aspects of a non-limiting example of the rotary blower of  FIG. 1  with the rotors at a first rotational position, which is the rotational position illustrated in  FIG. 1 . 
         FIG. 3  schematically illustrates a cross-sectional view depicting some aspects of a non-limiting example of the rotary blower of  FIG. 1 , from the perspective of  FIG. 2  but with the rotors at a second rotational position. 
         FIG. 4  schematically illustrates a cross-sectional view depicting some aspects of a non-limiting example of the rotary blower of  FIG. 1 , from the perspective of  FIG. 2  but with the rotors at a third rotational position. 
         FIG. 5  schematically illustrates a cross-sectional view depicting some aspects of a non-limiting example of a 3-lobed rotary blower in accordance with an embodiment of the present invention. 
         FIGS. 6A-6C  illustrate cross-sectional views depicting some aspects of non-limiting examples of lobe side seal inserts and a lobe tip seal insert in accordance with an embodiment of the present invention. 
         FIG. 7  depicts a cross-section illustrating some aspects of a non-limiting example of a lobe side seal insert in accordance with an embodiment of the present invention. 
         FIG. 8  depicts a cross-section illustrating some aspects of a non-limiting example of a lobe tip seal insert in accordance with an embodiment of the present invention. 
         FIG. 9  depicts a cross-section illustrating some aspects of a non-limiting example of a pusher weight in accordance with an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS 
     For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended. Any alterations and further modifications in the described embodiments, and any further applications of the principles of the invention as described herein are contemplated as would normally occur to one skilled in the art to which the invention relates. 
     Referring to  FIG. 1 , some aspects of a non-limiting example of a rotary blower  10  are illustrated in accordance with an embodiment of the present invention. In one form, rotary blower  10  is a Roots blower. In other embodiments, rotary blower  10  may take other forms. In one form, rotary blower  10  includes a pair of rotors, i.e., a driving rotor  12  in mesh with a driven rotor  14 . In one form, each of driving rotor  12  and driven rotor  14  are 2-lobed rotors. In other embodiments, driving rotor  12  and driven rotor  14  may be 3-lobed rotors, 4-lobed rotors, or rotors having any number of lobes. Driving rotor  12  and driven rotor  14  are supported by respective shafts  16 ,  18  and  20 ,  22 . Shafts  16 ,  18 ,  20  and  22  may be integral with rotors  12 ,  14 , or may be separate components affixed or mounted onto or into rotors  12 ,  14 . Shafts  16 ,  18 ,  20  and  22  are supported by respective bearings  24 ,  26 ,  28  and  30 . 
     Driving rotor  12  and driven rotor  14  are disposed radially within a housing  32 , which cooperates with driving rotor  12  and driven rotor  14  to pump or compress a fluid, such as air. Driving rotor  12  and driven rotor  14  are disposed axially between head plates  34  and  36 . Housing  32  is coupled, e.g., bolted, to head plates  34  and  36 . Bearings  24 ,  26 ,  28  and  30  are mounted in and supported by head plates  34  and  36 . Bearings  24 ,  26 ,  28  and  30  transmit radial and thrust loads from rotors  12  and  14  to head plates  34  and  36 . In one form, bearings  24 ,  26 ,  28  and  30  are rolling element bearings. For example, in the depicted embodiment of  FIG. 1 , bearings  26  and  30  are ball thrust bearings, whereas bearings  24  and  28  are roller bearings. In other embodiments, one or more of bearings  24 ,  26 ,  28  and  30  may be one or more other types of bearings. 
     Driving rotor  12  is supplied with shaft power via a shaft power source, such as an electric motor (not shown). Driving rotor  12  is operative to supply mechanical power to driven rotor  14  via gears  38  and  40 . Gears  38  and  40  are mounted on respective shafts  16  and  20  of respective driving and driven rotors  12  and  14 , and are in mesh with each other. Gears  38  and  40  are operative to maintain a desired angular relationship between driving rotor  12  and driven rotor  14 , and to transmit rotational motion and power from driving rotor  12  to driven rotor  14 . In various embodiments, a plurality of seals (not shown) may be employed to prevent the leakage of oil and/or compressed gas/fluids into undesired portions of rotary blower  10 . End plate covers (not shown) may be employed to cover the bearings  24 ,  26 ,  28 ,  30  and gears  38 ,  40 . 
     Referring to  FIGS. 2-4 , in conjunction with  FIG. 1 , during operation of rotary blower  10 , an inlet gas stream to be pumped or compressed enters rotary blower  10  through an inlet  42 , and the inlet gas is trapped in chambers formed between lobes  44  and the blower body or housing  32 , and is forced out of rotary blower  10  at an outlet  46 . In conventional rotary blowers, three types of clearances are typically used in order to allow rotation of the rotors relative to the housing and relative to each other. Examples of such clearances that occur in conventional blowers are illustrated in  FIGS. 2-4 , which are exaggerated for purposes of illustration. In the depictions of  FIG. 1-4 , some aspects of the present invention, such as the lobe seal inserts  58 ,  60  illustrated in and described with respect to  FIG. 5-9  are not shown in order to illustrate the clearances. One such clearance is lateral clearance  48 , which is the clearance between the rotors  12 ,  14  (including lobes  44 ) and the head plates, e.g., such as head plates  34  and  36 . Another such clearance is diameter or diametral clearance  50 , which is the radial clearance between the rotor lobes and the housing, e.g., housing  32 . A third such clearance is the clearance between rotors, or between lobes, e.g., parallel lobes, such as 30° clearance  52 . These clearances are typically calculated in consideration of thermal effects, such as dilation or thermal expansion. In conventional rotary blowers, the blower may crash or seize or otherwise be damaged if the clearances are too small. The size of the clearances or amount of clearance impacts blower efficiency. For example, efficiency decreases with increasing clearance, e.g., due to leakage through the clearances. Embodiments of the present invention reduce or eliminate the diameter clearance and the clearance between rotors (lobes), e.g., the 30° clearance, via the use of lobe seal inserts (not shown in  FIG. 1-4 ). 
     Referring to  FIGS. 5-9 , some aspects of a non-limiting example of a 3-lobed rotary blower  10 A in accordance with an embodiment of the present invention is illustrated. Rotary blower  10 A includes meshed driving rotor  12 A and driven rotor  14 A. Each of driving rotor  12 A and driven rotor  14 A have three lobes  44 A. Each lobe  44 A has a tip  54  and two sides  56 . Each lobe  44 A includes a lobe tip seal insert  58  mounted thereon. Some aspects of a non-limiting example of lobe tip seal insert  58  are illustrated in  FIG. 5 ,  FIG. 6A  and  FIG. 8 . Each lobe  44 A also includes two lobe side seal inserts  60  mounted thereon, one lobe side seal insert  60  on each side  56 . Some aspects of a non-limiting example of lobe side seal insert  60  are illustrated in  FIG. 5 ,  FIG. 6B ,  FIG. 6C  and  FIG. 7 . In other embodiments, a greater amount of lobe tip seal inserts  58  and lobe side seal inserts  60  may be employed. Some embodiments may include only lobe tip seal insert(s)  58  or only lobe side seal insert(s)  60 . In one form, lobe tip seal inserts  58  and lobe side seal inserts  60  are flexible and compliant. In other embodiments, portions of lobe tip seal inserts  58  and lobe side seal inserts  60  may be rigid. 
     In one form, the material used to form lobe tip seal inserts  58  and lobe side seal inserts  60  is different than the material used to form the balance of rotors  12 A and  14 A. For example, the material used to form lobe tip seal inserts  58  and lobe side seal inserts  60  may be non-metallic, whereas the material used to form the balance of rotors  12 A and  14 A may be metallic in some embodiments. For instance, in some embodiments, lobe tip seal inserts  58  and lobe side seal inserts  60  may be formed from, for example, a polymeric or composite or other non-metallic material. In some embodiments, preferable materials used to make lobe tip seal inserts  58  and lobe side seal inserts  60  are capable of continuous use at temperatures up to 180° C.; supports sliding speeds up to 40 m/s, and have a relatively low coefficient of friction. The materials used to make lobe tip seal inserts  58  and lobe side seal inserts  60 , and the corresponding coefficients of friction, may vary with the needs of the particular application. 
     Each lobe tip seal insert  58  is disposed at tip  54  of each lobe  44 A. In one form, each lobe tip seal insert  58  is constructed and operative to seal against housing  32  and to prevent or reduce leakage between each lobe  44 A and housing  32 . In some embodiments, each lobe tip seal insert  58  is also constructed and operative to seal against portions of the opposite rotor, e.g., at a location  12 A 1 ,  14 A 1  between the lobes  44 A, and also at the base or bottom or radially inward portion  44 A 1  of the lobes  44 A, to prevent or reduce leakage between each lobe  44 A of one rotor and location  12 A 1 ,  14 A 1  of the other rotor, and between each lobe  44 A of one rotor and the base portions  44 A 1  of lobes  44 A on the other rotor. In some embodiments, each lobe tip seal insert  58  is constructed to contact housing  32  during the operation of blower  10 . In some embodiments, each lobe tip seal insert  58  is constructed to engage in sliding contact with housing  32  during rotation of the rotors, i.e., during operation of rotary blower  10 . 
     In a particular embodiment, each lobe tip seal insert  58  is constructed to have an interference fit  64  with housing  32 , e.g., as illustrated in  FIG. 6A , wherein a free surface boundary  66  of a free lobe tip seal insert  58  (e.g., the sealing surface boundary of a lobe tip seal insert  58  not compressed by housing  32  or an adjacent rotor) extends beyond the compressed surface boundary  68  of a lobe tip seal insert  58  in the interference condition. The interference condition occurs when lobe tip seal  58  on one lobe  44 A is compressed by interference with housing  32  or with an adjacent rotor at a location  12 A 1 ,  14 A 1  between lobes or at the base or bottom portion  44 A 1  of the meshing lobe  44 A. The compressed boundary  68  is the boundary of the installed lobe tip seal insert  58  after being compressed due to the interference fit with housing  32  or with an adjacent rotor, e.g., as depicted in  FIG. 6A , which illustrates the interference with housing  32 . In other embodiments, lobe tip seal inserts  58  may be constructed to reduce diameter clearance  50  ( FIG. 2 ) without contacting housing  32  under some or all operating conditions, or may be constructed to reduce diameter clearance  50  by contacting housing  32  with little or no interference, e.g., under some or all operating conditions. 
     In one form, each lobe  44 A includes a pusher weight  62 , e.g., a rod. In the depiction of  FIG. 5  and  FIG. 9 , pusher weight  62  is a rod having a circular cross section. In other embodiments, pusher weight  62  may have any suitable geometric configuration. Each pusher weight  62  is constructed and operative to impart a radially outward, centrifugal load on a corresponding lobe tip seal insert  58 , e.g., to aid in loading lobe tip seal insert  58  in a direction toward housing  32  and toward the lobe and rotor that the lobe  44 A is meshing with. The radially outward loading may, for example, aid in maintaining desired contact loading between lobe tip seal insert  58  and housing  32 , and between the lobe tip seal insert  58  and the lobe and rotor it is meshing with. Other embodiments may not employ a pusher weight. 
     In one form, each lobe  44 A includes a tip recess  70  disposed at the tip  54  of the lobe. Lobe tip seal insert  58  is mounted in tip recess  70 . Other embodiments may not include a tip recess. In one form, tip recess  70  includes a dovetail  72  for mating with a corresponding dovetail  74  on lobe tip seal insert  58  for retaining lobe tip seal insert  58  on lobe  44 A. In other embodiments, other geometric configurations and/or fasteners may be employed to retain lobe tip seal insert  58  onto lobe  44 A. 
     Each lobe side seal insert  60  is disposed at side  56  of the each lobe  44 A. In one form, each lobe side seal insert  60  of one rotor is constructed to seal against an adjacent lobe  44 A in mesh therewith of the other rotor, including against an adjacent lobe side seal insert  60 . Each lobe side seal insert  60  is constructed and operative to prevent or reduce leakage between adjacent lobes  44 A in mesh with each other, e.g., while the lobes are meshing. In some embodiments, each lobe side seal insert  60  is constructed to contact and seal against the adjacent lobe in mesh therewith (including contacting and sealing against the lobe side seal insert  60  on the adjacent lobe) during operation of blower  10 . In some embodiments, each lobe side seal insert  60  is constructed to engage in sliding contact with the adjacent lobe  44 A in mesh therewith (including sliding contact with an adjacent lobe side seal insert  60 ) during rotation of the rotors, i.e., during operation of rotary blower  10 . 
     In a particular embodiment, each lobe side seal insert  60  is constructed to have an interference fit  76  with the adjacent meshing lobe  44 A, e.g., as illustrated in  FIG. 6B , wherein a free surface boundary  78  of a free lobe side seal insert  60  (e.g., the sealing surface boundary of a lobe side seal insert  60  not compressed by an adjacent lobe  44 A, including the adjacent lobe side seal  60 ) extends beyond the compressed surface boundary  80  of a lobe side seal insert  60  in the interference condition. The interference condition occurs when lobe side seal insert  60  is compressed by interference with the adjacent meshing lobe  44 A, including the adjacent lobe side seal insert  60 , e.g., as depicted in  FIG. 6B . In other embodiments, lobe side seal inserts  60  may be constructed to reduce 30° clearance  52  ( FIGS. 3 and 4 ) without contacting the adjacent lobe  44 A in mesh therewith under some or all operating conditions, or may be constructed to reduce 30° clearance  52  by contacting the adjacent lobe  44 A in mesh therewith with little or no interference, e.g., under some or all operating conditions. The interference may be generated, for example, by constructing the sealing surface of lobe side seal inserts  60  to protrude beyond the surface of the balance of lobe  44 A by a desired distance  82 . 
     In one form, each lobe  44 A includes a side recess  84  disposed on each side  56  of the lobe. Lobe side seal insert  60  is mounted in side recess  84 . Other embodiments may not include a side recess. In one form, side recess  84  includes a dovetail  86  for mating with a corresponding dovetail  88  on lobe side seal insert  60  for retaining lobe side seal insert  60  on lobe  44 A. In other embodiments, other geometric configurations and/or fasteners may be employed to retain lobe side seal insert  60  onto lobe  44 A. 
     Embodiments of the present invention include a rotary blower, comprising: a housing; a pair of meshed rotors disposed in the housing, each rotor having a plurality of lobes; and each lobe including a lobe tip seal insert mounted thereon and disposed at a tip of the each lobe, each lobe tip seal insert being constructed to seal against the housing and to prevent or reduce leakage between each lobe and the housing. 
     In a refinement, each lobe tip seal insert is constructed to engage in sliding contact with the housing during rotation of the rotors. 
     In another refinement, the rotary blower further comprises a plurality of pusher weights, each pusher weight being constructed to impart a radially outward load on a corresponding lobe tip seal insert. 
     In yet another refinement, each lobe includes a tip recess formed at the tip of the lobe; wherein the lobe tip seal insert is mounted in the tip recess. 
     In still another refinement, each lobe tip seal insert on one rotor is constructed to contact and seal against the other rotor at a location between the lobes and at a base of the lobes. 
     In yet still another refinement, each lobe further includes a lobe side seal insert mounted thereon and disposed on a side of the each lobe, each lobe side seal insert on each lobe on one rotor being constructed to contact and seal against an adjacent lobe in mesh therewith of the other rotor and to prevent or reduce leakage between adjacent lobes in mesh with each other. 
     In a further refinement, each lobe side seal insert is constructed to engage in sliding contact with the adjacent lobe during rotation of the rotors. 
     In a yet further refinement, each lobe includes a side recess formed at the side of the lobe; and wherein the lobe side seal insert is mounted in the side recess. 
     In a still further refinement, each lobe side seal insert and each lobe tip seal insert is non-metallic. 
     Embodiments of the present invention include a rotary blower, comprising: a pair of meshed rotors, each rotor having a plurality of lobes; and each lobe including a lobe side seal insert mounted thereon and disposed on a side of the each lobe, each lobe side seal insert on each lobe on one rotor being constructed to seal against an adjacent lobe in mesh therewith of the other rotor and to prevent or reduce leakage between adjacent lobes in mesh with each other. 
     In a refinement, each lobe side seal insert is constructed to engage in sliding contact with the adjacent lobe during rotation of the rotors. 
     In another refinement, each lobe includes a side recess formed at the side of the lobe; and wherein the lobe side seal insert is mounted in the side recess. 
     In yet another refinement, the rotary blower further comprises a housing, wherein the pair of meshed rotors is disposed in the housing; and wherein each lobe further includes a lobe tip seal insert mounted thereon and disposed at a tip of the each lobe, each lobe tip seal insert being constructed to contact and seal against the housing and to prevent or reduce leakage between each lobe and the housing. 
     In still another refinement, each lobe tip seal insert is constructed to engage in sliding contact with the housing during rotation of the rotors. 
     In yet still another refinement, each lobe tip seal insert and each lobe side seal insert is non-metallic. 
     In a further refinement, each lobe includes a tip recess formed at the tip of the lobe; and wherein the lobe tip seal insert is mounted in the tip recess. 
     In a yet further refinement, each lobe tip seal insert on one rotor is constructed to contact and seal against the other rotor at a location between the lobes and at a base of the lobes. 
     In a still further refinement, the rotary blower further comprises a plurality of pusher weights, each pusher weight being constructed to impart a radially outward load on a corresponding lobe tip seal insert. 
     Embodiments of the present invention include a rotary blower, comprising: a housing; a pair of meshed rotors disposed in the housing, each rotor having a plurality of lobes; and means for contacting and sealing against the housing and to prevent or reduce leakage between each lobe and the housing. 
     In a refinement, the rotary blower further comprises means on each lobe for contacting and sealing against an adjacent lobe in mesh therewith and to prevent or reduce leakage between adjacent lobes in mesh with each other. 
     While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only the preferred embodiments have been shown and described and that all changes and modifications that come within the spirit of the inventions are desired to be protected. It should be understood that while the use of words such as preferable, preferably, preferred or more preferred utilized in the description above indicate that the feature so described may be more desirable, it nonetheless may not be necessary and embodiments lacking the same may be contemplated as within the scope of the invention, the scope being defined by the claims that follow. In reading the claims, it is intended that when words such as “a,” “an,” “at least one,” or “at least one portion” are used there is no intention to limit the claim to only one item unless specifically stated to the contrary in the claim. When the language “at least a portion” and/or “a portion” is used the item can include a portion and/or the entire item unless specifically stated to the contrary. 
     Unless specified or limited otherwise, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. Further, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings.