Abstract:
Blower made up of at least two axially stacked, interlocking fans. Each fan is enclosed in a housing the axially opposite ends of which are flanged. Opposing flats on immediately neighboring flanges are formed with complementary twist-locking features. The twist-locking features are configured in such a way that when the fans are stacked, the opposing flats will not be in contact with each other unless the housings are twisted out of axial alignment to bring the opposing flats flush together, and such that with the opposing flats flush in contact, twisting the housings back into axial alignment locks them together.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention relates to a blower having a plurality of fans connected or engaged each other in a rotational axis direction. 
   2. Description of the Related Art 
   In order to improve a capacity of air flow and a static pressure generated by a fan without increasing its impeller&#39;s diameter, a blower called “a double fan” is widely used in which a plurality of axial fans are arranged along the rotational axis thereof. 
   In a conventional blower having a plurality of fan impellers, two or more impellers are encased in a single housing or each impeller is encased in each housing, and the housings are connected with each adjoining housing in rotational axis direction. Generally, a large amount of development cost is required to design a new blower including a design of its housing, therefore one way for realizing cost reduction is to connect or engage a plurality of existing axial fans or centrifugal fans in rotational axis direction, which meets a performance requested for the new blower. 
   There are two major ways to connect or engage two or more adjoining housings. One way is that flanges of the housings are fixedly coupled to each other by screws and the other is that elastic hooks formed on one housing are engaged with the recesses of the other housing. 
   In the case where the fans are fixedly connected by screws, however, special tool such as screwdriver or wrench may be required. This increases the number of steps for connecting the blowers as well as the number of parts of the blower, thereby the cost for producing the blower may increases because of its complex structure of the blower. 
   In connecting the adjoining fans by elastic hooks, on the other hand, since the elastic hooks can be formed at the same time as the housing is formed by a molding process, the cost for the housing with such elastic hooks may not increase. Also, the elastic hooks can be engaged very simply without increasing the number of steps for engaging. 
   However, when the connection by means of the elastic hooks is performed, there are two requirements contradicting each other. One requirement is for securing a sufficient elasticity caused by elastic deformation which may be required for completing the engaging step to make the two adjoining fans engage and the other requirement is for a sufficient engaging force. Specifically, in the case where the elasticity of the elastic hooks is increased to realize an easier engaging step, the engaging force decreases and the insufficient engaging force would be realized. On the other hand, in the case where the elasticity of the elastic hooks is decreased, the engaging force increases and the engaging step would not be accomplished, because the elastic hooks may be damaged or the housing may be warped. 
   BRIEF SUMMARY OF THE INVENTION 
   According to one aspect of the invention, there is provided a blower comprising two fans which are connected or engaged in a rotational axis direction. Each fan has a housing, at each area opposed upper or lower sides of adjoining two housing, the lower side of the upper housing and the upper side of the lower housing has flat housing portions. And two fans of the blower are held as the manner that two adjoining housings are located in parallel each other while being turned in a predetermined rotational angle around the rotational axis of the impeller, for making contact the flat housing portions of the opposed housings each other. On, near or in separate area from the flat housing portions, upper and lower housing engaging portions are formed, respectively. When decreasing the rotational angle from the predetermined rotational angle, the engaging portions come to be engaged each other, so that the two flat housing portions are fixedly contacting and not separated from each other in the rotational axis of the impeller. Further, upper and lower housing stoppers are formed on the opposed surfaces of the two adjoining housings. When the rotational angle is decreased and the rotational angle come to zero, the lower housing stopper comes into contact with the upper housing stopper. In this situation, the two adjoining housings have a continuous contour aligned with each other, having a contour shape such as single rectangular parallelepiped. As a result, the upper and lower housings are fixed with each other. This structure can be used also in a combination of a housing having a fan and a housing having a stationary vane built therein. Especially in the case where an axial fan is used, the cylindrical ends of each housing are open and have little space to form such engaging parts mentioned above, therefore it may be preferable that such engaging parts should be formed at flange portions which is formed at each of four corners in rectangular shape of the housing. 
   Additionally, in the upper and lower housing engaging portions said above, axial recesses and axial protrusions can be formed in opposed location to make the engagement of the two adjoining housing be fastened each other. In this way, the housings can be firmly fixed in a way that each of the two adjoining housings cannot be separated in the rotational axis of the impeller. 

   
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       FIG. 1  is perspective views showing a blower according to a first embodiment of the invention. 
       FIG. 2  is perspective views showing only the essential parts of the blower including the engaging portions of the fans according to the first embodiment of the invention. 
       FIG. 3  is plan views showing a blower according to the first embodiment of the invention. 
       FIG. 4  is perspective views showing a blower according to a second embodiment of the invention. 
       FIG. 5  is perspective views showing only the essential parts of the blower including the engaging portions of the fans according to the second embodiment of the invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   An embodiment of the invention is explained below with reference to the drawings. 
   In the description of an embodiment that follows, each of the four directions is indicated as viewed on the drawings unless otherwise specified, and not specifically limited in embodying the invention. Also, the uppercases suffixes A and B attached to the reference numerals in the description and drawings designate the component parts of the axial fans  10 A,  110 A,  10 B, respectively. The uppercase suffix C attached to the reference numerals in the drawings, on the other hand, designates the component parts of the stationary vane fans  11 C,  111 C. The component parts carrying no uppercase suffix designate common or independent parts having similar functions. 
   First Embodiment 
     FIG. 1  is perspective views showing a blower according to a first embodiment of the invention. Specifically,  FIG. 1C  designates an assembly completed by coupling two axial fans  10 A,  10 B, and  FIG. 1A ,  FIG. 1B  the states before being coupled.  FIG. 2  is enlarged views of the engaging portion of each fan constituting the essential parts of the blower according to the first embodiment of the invention.  FIG. 3  is top plan views of the blower shown in  FIG. 1 . 
   (1-1) Blower Configuration 
   Referring to  FIG. 1 , the blower  1  is configured of two axial fans  10 A,  10 B serially coupled to each other in the direction of the rotational axis. 
   The axial fans  10  each include a cylindrical peripheral wall  21  and an impeller  2  consisted by a plurality of blades  22  regularly arranged on the outer peripheral surface of the peripheral wall  21 . 
   Also, the axial fans  10  each include a housing  4  with a cylindrical portion  41  having a cylindrical inner peripheral surface  41   a  larger in diameter than the radial outer edge of the blades  22  and concentric with the rotational axis of the impeller  2 . 
   Further, an electric motor (not shown) to rotate the impeller  2  relatively to the housing  4  is held on the housing  4 . The electric motor is a DC brushless motor including a shaft fixed at the rotational center of the impeller  2 , a bearing for rotatably supporting the shaft, a bearing holder supporting the bearing on the housing  4 , a stator including a plurality of coils fixed on the outer periphery of the bearing holder, and a rotor magnet fitted on the inner peripheral surface of the cylindrical peripheral wall  21  of the impeller  2 . 
   The axial fans  10  can be used independently of each other. According to this embodiment, the lower axial fan  10 A arranged on the axially lower side is combined with the upper axial fan  10 B arranged on the axially upper side. 
   (1-2) Housing of Axial Fans 
   The ends of the cylindrical portion  41  of the axial fan  10 A are open in axial direction, and a plurality of flanges  42  are formed radially outward of at least the end of the cylindrical portion  41  in opposed relation to the axial fan  10 B. The flanges  42  are arranged in four directions at 90° intervals around the center axis of the cylindrical portion  41 . The edges of the flanges  42  are formed at 90° so that the flanges  42  as a whole substantially assume the shape of a square. The axial fans  10 A and  10 B, when arranged serially along the axis, have the flanges  42 A and  42 B aligned with each other in axial direction. 
   By forming the flanges  42 A,  42 B of the axial fans  10 A,  10 B in the same shape as shown in  FIG. 3 , the blower  1  can be shaped in the same planar form as the axial fans  10 A,  10 B. 
   Before combining the axial fans  10 A,  10 B, the rotational axis of the impeller is displaced by angle φ from the center axis of the impeller. Also, the angle is defined as zero in the case where the axial fan  10 A is rotated with the contour thereof into alignment with that of the axial fan  10 B, i.e. in the case where the axial fans  10 A,  10 B share the same planar form. 
   (1-3) Flanges 
   In  FIG. 2 , that surface of the flanges  42 A of the axial fan  10 A which is in contact with the flanges  42 B of the axial fan  10 B forms a flat housing portion  43 A perpendicular to the rotational axis of the impeller  2 A. In similar fashion, that surface of the flanges  42 B of the axial fan  10 B which is in contact with the flanges  42 A of the axial fan  10 A forms a flat housing proton  43 B perpendicular to the rotational axis of the impeller  2 B. The flat housing portion  43 A of the axial fan  10 A and the flat housing portion  43 B of the axial fan  10 B are in slidable contact with each other, and function as a housing engaging portion and a housing stopper, respectively. 
   Each flange  42 A has a protrusion  44 A providing the housing stopper on the flat housing portion  43 B side thereof in opposed relation to the flat housing portion  43 A. The protrusion  44 A is formed with a radial recess  46 A providing a housing engaging portion. Also, each flange  42 B is formed with a notch  45 B cut off from the flat housing portion  43 B providing a stopper corresponding to the protrusion  44 A. Further, the notch  45 B is formed with a radial protrusion  47 B providing an housing engaging portion in such a shape as to engage the radial recess  46 A closely. 
   The protrusion  44 A and the notch  45 B are so shaped as to complement each other. Once the flat housing portion  43 A and the flat housing portion  43 B are rotationally slid to reduce the angle φ around the rotational axis of the impeller to zero, therefore, the radial protrusions  47 B are fitted, under light pressure, into the radial recesses  46 A located at four points, respectively, so that each notch  45 B and the corresponding protrusion  44 A are fitted closely with each other. 
   More specifically, each protrusion  44 A is formed with the radial recess  46 A along the peripheral direction around the rotational axis. In the radial recess  46 A, the protrusion  44 A is cut off by one half of the height of the protruded portion from the flat housing portion  43 A, and the peripheral and inner ends thereof are open. The protrusion  44 A has the same height as the thickness of the flange  42 . Each notch  45 B is cut off in the same shape as the protrusion  44 A including the flat housing portion  43 B. Further, the radial protrusion  47 B in the shape corresponding to the radial recess  46 A is formed around the rotational axis inside the notch  45 B. The radial protrusion  47 B is one half as thick as the flange  42 B, and has the same radial thickness as the radial recess  46 A. The height and the radial thickness of the radial recess  46 A are equal to or slightly smaller than the thickness and the radial thickness, respectively, of the radial protrusion  47 B. 
   The engagement between the radial recess  46 A and the radial protrusion  47 B providing the engaging portions restricts the axial movement of the axial fans  10 A,  10 B. Also, the friction generated by the contact between the protrusion  44 A including the radial recess  46 A and the notch  45 B including the radial protrusion  47 B restricts the peripheral movement of the axial fans  10 A,  10 B. Further, the flat surface  44 Aa providing a lower flat stopper surface formed at right angles to the peripheral direction of the protrusion  44 A and the flat housing portion  43 A comes into contact with the flat surface  45 Ba providing an upper flat stopper surface formed at right angles to the peripheral direction of the notch  45 B and the flat housing portion  43 B, so that the axial fans  10 A,  10 B are peripherally set in position. 
   The steps of fitting the axial fans  10 A,  10 B are described below. 
   First, as shown in  FIGS. 1A and 3A , the flat housing portion  43 A of each flange  42 A of the axial fan  10 A and the corresponding flat housing portion  43 B of the flange  42 B of the axial fan  10 B are brought into contact with each other. Next, the axial fan  10 B is rotated counterclockwise, as taken in the plan view of  FIG. 3 , around the rotational axis of the impeller with respect to the axial fan  10 A. As a result of this process, the radial protrusion  47 B is fitted in the corresponding radial recess  46 A. Finally, the axial fan  10 B is rotationally slid until the flat surface  44 Aa and the flat surface  45 Ba come into contact with each other. As a result of this process, as shown in  FIGS. 1C and 3C , the flanges  42 A and  42 B come into alignment with each other thereby to complete the blower  1 . 
   The axial fans  10 A,  10 B are peripherally set in position by the contact between the flat surface  44 Aa of the protrusion  44 A and the flat surface  45 Ba of the notch  45 B and the resulting restriction of rotation of the axial fan  10 A with respect to the axial fan  10 B. 
   Incidentally, the radial protrusion  47 A may be formed on the protrusion  44 A. In such a case, however, the radial recess  46 B is formed in the notch  45 B. 
   (1-4) Miscellaneous 
   According to this embodiment, even after assembling the axial fan  10 A on the axial fan  10 B, the assembly can be disassembled by being rotationally slid in the opposite direction (clockwise) to the fitting direction. In other words, the axial fans  10 A,  10 B can be used independently of each other. As a result, the axial fans  10 A,  10 B each can be used as a standard axial fan, and without any design change, assembled into and used as the blower  1 . 
   Also, as shown in  FIG. 5 , an axial protrusion  47   a  that formed a tapered step may be formed in peripheral direction on each radial protrusion  47  in an axial recess  46   a  that formed a tapered accommodation portion of the radial recess  46  in peripheral direction to accommodate the step  47   a . This structure is conveniently used in the case where the axial fans  10 A,  10 B, once engaged with each other, are not required to be disassembled. 
   The axial fans  10 A,  10 B, if not required to be disassembled after mutual engagement and thus to be coupled more strongly, may be fixed with an adhesive. The use of an adhesive increases the fastening force on the one hand and can cut off the vibrations between the housings at the same time. 
   To fix the axial fans  10 A,  10 B with special strength, the welding or screwing or the pressure bonding or fitting with a separate material may be used instead of the adhesive. 
   Also, the axial fan  10 A and the axial fan  10 B may have different characteristics such as the air capacity, static pressure, axial thickness, diameter of the impeller  2  or the rotational speed of the impeller  2 . 
   Further, the blower  1  may be configured of three or more axial fans  10  arranged in axial direction. In the case where a number of axial fans  10  make up the blower  1 , the fixing structure with its fixing ease according to this embodiment further enhances the advantage of the invention that the workability is improved. 
   Further, the provision of the protrusion  44  on the flange  42  of one axial fan  10  in axial direction and the provision of the notch  45  on the flange  42  of the other axial fan  10  makes it possible to couple the axial fans  10  using a single type of the housing  4 . Thus, mass production is made possible for a reduced production cost. 
   Also, the axial fans  10  according to this embodiment are better arranged in such a manner that the impellers of axially adjacent axial fans  10  are rotated in opposite directions while blowing the air in the same axial direction. By doing so, both the static pressure and the air capacity of the blower  1  are improved. 
   As described above, in the blower  1  according to this embodiment, the flat housing portions  43 A,  43 B of the axial fans  10 A,  10 B are rotated in sliding contact with each other, and therefore the axial fans  10 A,  10 B can be coupled to each other with a simple operation. In addition, the axial fans  10 A,  10 B are coupled completely with each other by the engagement between the protrusion  44  and the notch  45  and the friction between the flat housing portions  43  in contact with each other. Thus, the stress acting on the protrusion  44  and the notch  45  is distributed and an excessive load is prevented from being imposed on the flanges  42 . As a result, the housing  4  is protected from damage or curving. Also, in view of the fact that the protrusion  44  and the notch  45 , as shown in FIG.  2 B, engage each other without being displaced outward or forming a gap, no air leaks from between the housings  4  to deteriorate the blowing characteristics. 
   Second Embodiment 
     FIG. 4  is perspective views showing a blower according to a second embodiment of the invention. 
   (2-1) Blower Configuration 
   The blower  101  according to this embodiment is configured of an axial fan  110  having a similar structure as the axial fan  10  according to the first embodiment and a stationary vane  111  having fixed blades  123  which are combined serially in the direction of the rotational axis. The stationary vane  111  includes a plurality of fixed blades  123  regularly arranged on the circumference and a housing  104  having a cylindrical portion  141  for fixing the outer peripheral ends of the fixed blades  123 . 
   With this configuration, the static pressure characteristic of the axial fan  110  can be improved. In addition, the use of a plurality of the axial fans  110  in combination can further improve the performance of the blower  101 . 
   (2-2) Housing 
   The housing  104 C of the stationary vane  111 C, like the housing  104 A of the axial fan  110 A, has a plurality of flanges  142 C. The flanges  142 C each have a similar shape to the flanges  142 A of the axial fan  110 A. In this way, the stationary vane  111 C and the axial fan  110 A are arranged serially along the direction of the rotational axis in such a manner that the flanges  142 A and  142 C align with each other. 
   (2-3) Flanges 
   The surface of the flanges  142 C of the stationary vane  111 C which is in contact with the flanges  142 A of the axial fan  110 A forms a flat housing portion  143 C perpendicular to the rotational axis. By doing so, the flat housing portions  143 A and  143 C are slidable with each other. 
   The flanges  142 C of the stationary vane  111 C each have a notch  145 C. The protrusion  144  and the notch  145  are so shaped as to complement each other. The protrusion  144  is formed with a radial recess  146  along the periphery around the rotational axis. Also, the notch  145  is formed with a radial protrusion  147  in the shape corresponding to the radial recess  146  around the rotational axis. 
   As an alternative, the protrusion  144  may be formed with the radial protrusion  147  and the notch  145  with the radial recess  146 . 
   The flat housing portion  143 C formed on each flange  142 C of the stationary vane  111 C and the flat housing portion  143 A formed on each flange  142 A of the axial fan  110 A are brought into contact with each other and rotated around the rotational axis. Then, the radial protrusion  147 A is inserted in the radial recess  146 C. 
   As an alternative, according to this embodiment, the notch  145 C may be formed on each flange  142 C of the stationary vane  111 C and the notch  144 A on each flange  142 A of the axial fan  110 A. As another alternative, the notch  145 C may be formed on each flange  142 C of the stationary vane  111 C, and the protrusion  144 C may be formed on the corresponding flange  142 C along the rotational axis. 
   (2-4) Miscellaneous 
   Also, the blower  101  may be configured of at least one axial fan  110  and at least one stationary vane  111 . In this case, the protrusion  144  and the notch  145  may be formed on each component made up of an assembly of several stationary vanes  111  and axial fans  110 . By doing so, the assembly time can be reduced. Also, in the case where the blower  101  includes a number of stationary vanes  111  and axial fans  110 , the use of the fixed structure according to this embodiment and the resulting fixing ease further improves the effects of the invention including the workability. 
   The axial fans  110  are preferably arranged in such a manner as to discharge the air in the same direction along the rotational axis of the impeller. The insertion of the stationary vane  111  between the two axial fans  110  improves the characteristics of both air capacity and static pressure. Also, the static pressure characteristic is improved more preferably by arranging the impellers of the adjacent axial fans  110 , with or without the stationary blade  111  therebetween, to rotate in opposite directions as viewed from the axially upper side. 
   Other Embodiments 
   Each of the embodiments described above represents one aspect of the invention, to which the invention is not limited, and the invention is modifiable within the scope thereof. The material of the housings  4 ,  104 , for example, may be any of various resin or a die-cast aluminum product. Also, the protrusions  44 ,  144  and the notches  45 ,  145  may take any arbitrary shape as required. 
   Further, the cylindrical portions  41 ,  141  are not required to have a completely cylindrical inner peripheral surface, but may have a venturi-shaped inner peripheral surface with the diameter changing in the direction along the rotational axis of the impeller, or a wide tapered opening. 
   Also, the rotational axis of the impeller and the center axis of the housing are not required to coincide with each other but may be displaced from each other.