Patent Publication Number: US-2021167658-A1

Title: All-weather motor

Description:
TECHNICAL FIELD 
     The present invention relates to an all-weather motor used in an exposed state in the outdoor as a driving source for, for example, an unmanned aerial vehicle (commonly-called a drone) or the like that is remotely controlled. 
     BACKGROUND ART 
     In general, a motor tends to be filled with heat inside a housing due to heat generation of coils when starting operation. As motor performance is deteriorated when the heat generation of the motor is increased, it is necessary to cool the inside of the motor. Accordingly, an open-type motor is proposed, in which a heat dissipation fan is provided on one end side of the motor housing so that an air flow is taken in from an air intake port provided on one end side into an internal space and hot air inside the motor is discharged from an air discharge port on the other end side of the motor housing to thereby improve heat dissipation properties (refer to PTL 1: JP-A-2017-17983). 
     In contrast to the above, in a case where a motor unit is assembled to a pump unit, a totally-enclosed motor is also proposed, in which the motor is housed in a motor cover and the motor cover is joined to a motor base to seal the motor (refer to PTL 2: JP-A-2009-290981). 
     CITATION LIST 
     Patent Literature 
     PTL 1: JP-A-2017-17983 
     PTL 2: JP-A-2009-290981 
     SUMMARY OF INVENTION 
     Technical Problem 
     For example, a motor used as a driving source for an unmanned aerial vehicle (commonly-called a drone) that is remotely controlled is used with a high output mainly in the outdoor in many cases. In a case where the motor is continuously used with the high output, heat generation inside the motor is high, and it is necessary to widely secure an opening of a motor case for enhancing heat dissipation properties. However, there is a danger of causing a motor lock in this structure as it is difficult to prevent invasion of foreign matter such as dust or sand and invasion of water from the outside. 
     When the totally-enclosed motor not having the opening in the motor case is adopted in response to the above, the invasion of foreign matter or water into the motor can be prevented, but it is difficult to obtain the high output because heat generation of the motor is not dissipated; therefore, there is a danger of deterioration in flying performance. 
     In view of the above, an all-weather motor capable of preventing deterioration of motor performance due to heat generation of the motor and having dust-proof and drip-proof functions preventing invasion of foreign matter and water into the motor is required. 
     Solution to Problem 
     A disclosure applied to some embodiments described below has been made for solving the above problems, and an object thereof is to provide a highly durable all-weather motor capable of preventing deterioration of motor performance by enhancing heat dissipation properties and capable of maintaining motor performance by enhancing dust-proof and drip-proof performance. 
     The disclosure applied to some embodiments described below includes at least following structures. 
     An all-weather motor includes an attachment base, a bearing housing integrally assembled to the attachment base, a stator having a stator core integrally assembled to the bearing housing and a rotor having a rotor magnet supported to face the stator core and supported by the bearing housing so as to rotate through bearings, in which the rotor includes a rotating case body covering an outer peripheral side of the stator and both end sides in an axial direction of the bearing housing, having intake openings on one end side in the axial direction and having discharge openings on the other end side in the axial direction, and a fin provided on the other end side in the axial direction inside the rotating case body, and the intake openings and the discharge openings are respectively covered with a filter material with a prescribed opening diameter. 
     According to the above structure, both ends in the axial direction and outer peripheral surfaces of the stator and rotor forming the motor are covered by the rotating case body; therefore, foreign matter and water do not enter the inside of the motor easily. Moreover, the intake openings and the discharge openings are covered with the filter material; therefore, dust-proof and drip-proof effects are high. 
     The rotating case body integrated with the rotor rotates when the motor is activated, and the fin provided inside the rotating case body rotates, thereby taking in air from the intake openings on one end side in the axial direction of the rotating case body, and sending hot air generated inside the motor to an outer side in a radial direction by the fin on the other end side in the axial direction to be discharged from the discharge openings. 
     According to the above, it is possible to provide the all-weather motor capable of preventing deterioration of motor performance by enhancing heat dissipation properties of the motor and capable of maintaining motor performance by enhancing dust-proof and drip-proof performance. 
     It is preferable that air is taken in through the filter material in the axial direction from the intake openings provided on one end side in the axial direction of the rotating case body and is sent toward the outer side in the radial direction by the fin provided on an inner surface of the other end in the axial direction of the rotating case body to be discharged from the discharge openings through the filter material. 
     According to the above, when the motor is started, air is taken in from the intake openings of the rotating case body through the filter material to cool the stator core and the coil, and hot air is sent toward the outer side in the radial direction by rotation of the fin to be discharged from the discharge openings through the filter material; therefore, invasion of foreign matter and water can be prevented by the filter material while maintaining motor performance by enhancing heat dissipation properties. In particular, drip-proof performance can be enhanced due to existence of the filter material and discharge from the discharge openings. 
     It is preferable to use an opening diameter smaller than a clearance dimension between stator pole teeth and the rotor magnet as the opening diameter of the filter material. 
     According to the above, it is possible to prevent occurrence of the motor lock due to foreign matter such as dust being caught in the clearance between the stator pole teeth and the rotor magnet. 
     It is preferable that the filter material covering the intake openings is provided so as to be replaceable. 
     According to the above, maintenance work becomes easy as the filter material covering the intake openings easily gets dirty for removing dust or foreign matter at the time of taking in outdoor air and a filter function tends to be reduced. 
     It is preferable that air is taken in from the intake openings provided at a lower part in the axial direction of the rotating case body and is discharged from the discharge openings provided on the outer side in the radial direction at an upper part thereof in the axial direction. 
     According to the above, air is taken in from the intake openings provided at the lower part in the axial direction and is discharged from the discharge openings provided on the outer side in the radial direction at the upper part thereof in the axial direction; therefore, water does not enter any of openings easily and drip-proof performance can be enhanced. 
     A position where the intake openings are provided is preferably a lower end surface in the axial direction in consideration of drip-proof properties when the rotating case body is, for example, a bottomed cylindrical body. The intake openings are preferably provided on a lower surface in the axial direction when the rotating case body has curved surfaces not having an end surface. 
     Advantageous Effects of Invention 
     According to the above structures, it is possible to provide the highly durable all-weather motor capable of preventing deterioration of motor performance by enhancing heat dissipation properties and capable of maintaining motor performance by enhancing dust-proof and drip-proof performance. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a perspective exterior view of an all-weather motor used as a driving source for a flying object. 
         FIG. 2  is a vertical sectional view in an axial direction of the all-weather motor. 
         FIG. 3  is a perspective explanatory view of the vertical cross-sectional view in the axial direction of  FIG. 2  seen from intake opening side. 
         FIG. 4  is an exploded perspective view of the motor of  FIG. 1 . 
         FIG. 5  is a vertical cross-sectional view in the axial direction of an all-weather motor according to another example. 
         FIG. 6  is a perspective explanatory view of the vertical cross-sectional view in the axial direction of  FIG. 5  seen from intake opening side. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, an all-weather motor according to an embodiment will be explained with reference to the attached drawings of  FIG. 1  to  FIG. 6 . The embodiment will be explained by citing an all-weather motor  2  used as a driving source for an unmanned aerial vehicle (commonly-called a drone) as an example. The unmanned aerial vehicle (not shown) flies by transmitting an operation signal by a transmitter by remote control to rotate a propeller at high speed, which is rotated by driving of a plurality of motors supported in a vehicle body frame. A flight controller is provided in the vehicle body frame, which controls the motor driving by a transmission signal received through a receiver. 
     As shown in  FIG. 1 , a DC brushless motor is used for the all-weather motor  2 . As the DC brushless motor, an outer rotor motor in which the high output is expected is suitably used. A propeller  3  is integrally assembled to a rotor of the all-weather motor  2  as described later. Specifically, a pedestal plate  5  is fixed by plural screws  6  at a central part on an upper end surface of a rotating case body  4  forming the rotor. Tip end parts of the screws  6  are integrally assembled to the rotating case body  4  by screw fitting (see  FIG. 2 ). A shaft part  5   a  is provided to protrude on an upper surface of the pedestal plate  5 . The shaft part  5   a  is inserted into a shaft hole  3   a  (see  FIG. 2 ) of the propeller  3  to thereby assemble the propeller  3  onto the pedestal plate  5 . A stopper plate  7  is fixed so as to overlap with the propeller  3 . The stopper plate  7  overlaps with the propeller  3  while the shaft part  5   a  is inserted into a shaft hole  7   a  (see  FIG. 2 ) and is integrally fixed by screws  8 . 
     Next, a structure of the all-weather motor  2  will be explained with reference to  FIG. 2 . 
     A structure of a stator  9  will be explained. An attachment base  10  is used when, for example, the DC blushless motor is fixed to the vehicle body frame (not shown) of the unmanned aerial vehicle. Screw holes  10   a  for fixing the motor onto an attachment surface of, for example, the vehicle body frame or the like by screws are drilled on the attachment base  10 . The attachment base  10  is provided with a through hole  10   b  at a central part for reducing the weight. One end part  11   a  of a cylindrical bearing housing  11  is integrally fixed by screws  11   b  in a state of overlapping with the attachment base  10  so as to stand. 
     A stator core  12  is integrally assembled to the bearing housing  11  by press-fitting, welding, screw-fitting or combinations thereof. As the stator core  12 , a lamination core formed by laminating and pressing electromagnetic steel sheets, an integral core formed by electrical discharge machining or laser-cutting of a metal plate, a core made of a sintered metal formed by firing metal powder and other types of cores may be adopted. 
     In the stator core  12 , a plurality of pole teeth  12   a  are provided to protrude radially from an annular core back part. Coils  13  are wound on respective pole teeth  12   a  with insulation coating or through insulators. 
     Next, a structure of a rotor  14  will be explained. 
     The rotating case body  4  forming the rotor  14  is supported by both-end outer peripheral parts in a longitudinal direction of the bearing housing  11  through a first bearing  15  and a second bearing  16  so as to rotate. The first bearing  15  and the second bearing  16  are fixed to the outer periphery of the bearing housing  11  by, for example, press-fitting, welding, clearance-fitting and the like. 
     The rotating case body  4  is integrally assembled so that a first case body  4   a  covering an outer peripheral side and one end part in an axial direction of the bearing housing  11  and a second case body  4   b  covering the outer peripheral side and the other end part in the axial direction of the bearing housing  11  sandwich an annular back yoke  4   c  covering an outer peripheral side of the stator core  12 . The first case body  4   a  and the back yoke  4   c  are fixed by adhesion, and the second case body  4   b  and the back yoke  4   c  are screw-fixed by fixing screws  19  (see  FIG. 1 ). 
     An aluminum material and so on are used for the first case body  4   a  and the second case body  4   b  for reducing weight. Magnetic materials (magnetic materials such as iron and SUS) are used for the back yoke  4   c  for forming a magnetic path. On an inner peripheral surface of the annular back yoke  4   c,  an annular rotor magnet  4   d  magnetized into N-poles and S-poles alternately in a circumferential direction is supported. The rotor magnet  4   d  is arranged to face teeth tips of the pole teeth  12   a  of the stator core  12 . 
     Intake openings  4   e  are provided at plural places on an end surface  4   a   1  in the axial direction of the first case body  4   a.  Air is taken in from the intake openings  4   e  in the axial direction to thereby cool the stator core  12  and the coils  13  (stator  9 ). A fin  17  is integrally assembled to an inner end surface  4   b   1  in the axial direction of the second case body  4   b  by screws  17   a.  The fin  17  is assembled so that a base plate  17   b  overlaps with the inner end surface  4   b   1  in the axial direction by screw-fitting. A plurality of slats  17   c  extended in a radial direction are formed to stand in the circumferential direction on the base plate  17   b.  On a side surface part of the second case body  4   b  facing tip end parts on an outer peripheral side of the slats  17   c,  discharge openings  4   f  are provided. When the fin  17  rotates, air taken in from the intake openings  4   e  in the axial direction is sent toward an outer side in the radial direction and discharged from the discharge openings  4   f.    
     The above-described intake openings  4   e  and the discharge openings  4   f  are respectively covered with a filter material  18  (for example, mesh sheets made of nylon 66) having breathability and water repellency with a prescribed opening diameter (see  FIG. 3 ). The filter material  18  is fixed to inner peripheral surfaces of the first case body  4   a  and the second case body  4   b  by adhesion and the like. As the opening diameter (for example, a square hole with 77 μm in one side) of the filter material  18 , a diameter smaller than a clearance (for example, 160 μm) between the stator pole teeth  12   a  and the rotor magnet  4   d  is suitably used. According to the above, it is possible to prevent occurrence of the motor lock due to foreign matter such as dust being caught in the clearance between the stator pole teeth  12   a  and the rotor magnet  4   d,  and moreover, waterproof and drip-proof functions of the intake openings  4   e  and the discharge openings  4   f  can be also secured. 
     Though the filter material  18  covering the intake openings  4   e  may be fixed by adhesion and the like, it is desirable to be provided so as to be replaceable, for example, through a not-shown attachment. This facilitates maintenance work as the filter material  18  covering the intake openings  4   e  easily gets dirty for removing dust or foreign matter at the time of taking in outdoor air and a filter function tends to be reduced. The filter material  18  is not limited to the mesh sheet material but may be a porous sheet material such as sponge. Both a resin material and a metal material may be used as materials. 
     When the rotation case body  4  rotates together with the rotor  14 , air is taken in from the intake openings  4   e  in the axial direction through the water-repellent filter material  18  and sent toward the outer side in the radial direction by the fin  17  via the stator core  12  to be discharged through the discharge openings  4   f.    
     When the all-weather motor  2  is started, air taken in from the intake openings  4   e  of the rotation case body  4  through the filter material  18  cools the coils  13  of the stator core  12 , and then hot air is sent toward the outer side in the radial direction by the rotation of the fin  17  and is discharged from the discharge openings  4   f  through the filter material  18  as shown by arrows in  FIG. 2 . Accordingly, it is possible to prevent invasion of foreign mater and water by the filter material  18  while maintaining motor performance by enhancing heat dissipation properties. In particular, air is taken in from the intake openings  4   e  provided at a lower part in the axial direction and is discharged from the discharge openings  4   f  provided on the outer side in the radial direction at an upper part thereof in the axial direction in addition to the existence of the filter material  18 ; therefore, water does not enter any of the openings easily and the drip-proof properties can be enhanced. 
     As the stator  9  and the rotor  14  forming the all-weather motor  2  are covered with the rotating case body  4  at both ends in the axial direction and the outer peripheral surface according to the above structure, foreign matter does not enter the inside of the motor  2  easily. Furthermore, the intake opening  4   e  and the discharge openings  4   f  are covered with the filter material  18  and therefore dust-proof and drip-proof effects are high. 
     Moreover, when the all-weather motor  2  is activated, the rotating case body  4  integrated with the rotor  14  rotates and the fin  17  provided inside the rotation case body  4  rotates, thereby taking in air from the intake openings  4   e  on one end side in the axial direction of the rotating case body  4 , and sending hot air generated inside the motor to the outer side in the radial direction by the fin  17  on the other end side in the axial direction to be discharged from the discharge openings  4   f.    
     Accordingly, it is possible to provide the all-weather motor  2  capable of preventing deterioration of motor performance by enhancing heat dissipation properties of the motor and capable of maintaining motor performance by enhancing dust-proof and drip-proof performance. 
     An example of an assembly structure of the unmanned aerial vehicle including the above all-weather motor  2  will be explained with reference to  FIG. 3  and  FIG. 4 . The pedestal plate  5  is fixed to the second case body  4   b  of the rotating case body  4  by plural screws  6  (see  FIG. 3 ) in advance. The shaft part  5   a  provided in the pedestal plate  5  to protrude is inserted into the shaft hole  3   a  of the propeller  3  to thereby assemble the propeller  3  onto the pedestal plate  5 , and inserted into the shaft hole  7   a  so that the stopper plate  7  overlaps with the propeller  3  from above and integrally fixed by the screws  8 . The filter material  18  is adhered so as to cover the outer surface side of the intake openings  4   e  of the first case body  4   a  and the inner surface side of the discharge openings  4   f  of the second case body  4   b,  respectively (see  FIG. 4 ). 
     The stator  9  is integrally assembled to the bearing housing  11  screwed to the attachment base  10 . The first bearing  15  and the second bearing  16  are respectively assembled to both end parts in a longitudinal direction of the bearing housing  11 . The first case body  4   a  is supported so as to rotate with respect to the bearing housing  11  through the first bearing  15 , and the second case body  4   b  is supported so as to rotate with respect to the bearing housing  11  through the second bearing  16  (see  FIG. 3 ). 
     As shown in  FIG. 4 , the fin  17  is integrally assembled to the inner end surface  4   b   1  in the axial direction of the second case body  4   b  by screw-fitting using the screws  17   a.  The back yoke  4   c  supporting the rotor magnet  4   d  is assembled so as to be fitted to opening ends of the first case body  4   a  and the second case body  4   b,  respectively. Then, the first case body  4   a  and the back yoke  4   c  are fixed by adhesion, and the first case body  4   a  and the second case body  4   b  are integrally assembled through the back yoke  4   c  by screw-fitting the fixing screws  19  to an overlapped portion between the second case body  4   b  and the back yoke  4   c.    
     When the all-weather motor  2  is activated as shown in  FIG. 2 , the rotating case body  4  integrated with the rotor  14  rotates. At this time, the fin  17  inside the rotating case body  4  rotates, thereby taking in air in the axial direction from the intake openings  4   e  on one end side in the axial direction of the rotating case body  4 , and sending hot air generated inside the motor to the outer side in the radial direction by the fin  17  on the other end side in the axial direction to be discharged from the discharge opening  4   f.    
     Next, modification examples of the all-weather motor  2  are shown in  FIG. 5  and  FIG. 6 . The same numerals are given to the same members as those shown in  FIG. 1  to  FIG. 4  and explanation is invoked, and different structures will be mainly explained. The above-described all-weather motor  2  is used as the driving source for the unmanned aerial vehicle, which also can be used by arranging the first case body  4   a  and the second case body  4   b  of the rotating case body  4  upside down and, more specifically, by arranging the attachment base  10  and the propeller  3  upside down. 
     In  FIG. 5 , the intake openings  4   e  are provided at plural places on an end surface  4   b   2  in the axial direction of the second case body  4   b.  Air is taken in from the intake openings  4   e  in the axial direction to thereby cool the stator core  12  and the coils  13  (stator  9 ). The fin  17  is integrally assembled to an inner end surface  4   a   2  in the axial direction of the first case body  4   a  by the screws  17   a.  The fin  17  is assembled so that the base plate  17   b  overlaps with the inner end surface  4   a   2  in the axial direction by screw-fitting. A plurality of slats  17   c  extended in the radial direction are formed to stand in the circumferential direction on the base plate  17   b.    
     On a side surface part of the first case body  4   a  facing tip end parts on the outer peripheral side of the slats  17   c,  the discharge openings  4   f  are provided. When the fin  17  rotates, air taken in from the intake openings  4   e  in the axial direction is sent toward the circumferential direction and discharged from the discharge openings  4   f.    
     According to the above, it is possible to prevent occurrence of the motor lock due to foreign matter such as dust being caught in the clearance between the stator pole teeth  12   a  and the rotor magnet  4   d,  and moreover, waterproof and drip-proof functions of the intake openings  4   e  and the discharge openings  4   f  can be also secured. 
     An example of an assembly structure of the unmanned aerial vehicle including the above all-weather motor  2  will be explained with reference to  FIG. 6 . The pedestal plate  5  is fixed to the second case body  4   b  forming the rotating case body  4  by plural screws  6  in advance. The shaft part  5   a  provided in the pedestal plate  5  to protrude is inserted into the shaft hole  3   a  of the propeller  3  to thereby assemble the propeller  3  onto the pedestal plate  5 , and inserted into the shaft hole  7   a  so that the stopper plate  7  overlaps with the propeller  3  and integrally fixed by the screws  8 . The filter material  18  is adhered so as to cover the outer surface side of the intake openings  4   e  of the second case body  4   b  and the inner surface side of the discharge openings  4   f  of the first case body  4   a,  respectively. 
     The stator  9  is integrally assembled to the bearing housing  11  screwed to the attachment base  10 . The first bearing  15  and the second bearing  16  are respectively assembled to both end parts in the longitudinal direction of the bearing housing  11 . The first case body  4   a  is supported so as to rotate with respect to the bearing housing  11  through the first bearing  15 , and the second case body  4   b  is supported so as to rotate with respect to the bearing housing  11  through the second bearing  16 . In this case, it is preferable to use a sealed bearing as the first bearing  15 , whereby invasion of water is prevented. 
     The fin  17  is integrally assembled to the inner end surface  4   a   2  of the first case body  4   a  by screw-fitting using the screws  17   a.  The back yoke  4   c  supporting the rotor magnet  4   d  is assembled so as to be fitted to opening ends of the first case body  4   a  and the second case body  4   b,  respectively. Then, the first case body  4   a  and the back yoke  4   c  are fixed by adhesion, and the first case body  4   a  and the second case body  4   b  are integrally assembled through the back yoke  4   c  by screw-fitting the fixing screws  19  (see  FIG. 1 ) to an overlapped portion between the second case body  4   b  and the back yoke  4   c.    
     When the all-weather motor  2  is activated as shown in  FIG. 5 , the rotating case body  4  integrated with the rotor  14  rotates. At this time, the fin  17  inside the rotating case body  4  rotates, thereby taking in air in the axial direction from the intake openings  4   e  on one end side in the axial direction of the rotating case body  4 , and sending hot air generated inside the motor  2  to the outer side in the radial direction by the fin  17  on the other end side in the axial direction to be discharged from the discharge opening  4   f.    
     Accordingly, it is possible to provide the all-weather motor  2  capable of preventing deterioration of motor performance by enhancing heat dissipation properties of the motor and capable of maintaining motor performance by enhancing dust-proof and drip-proof performance and preventing invasion of foreign matter. 
     The all-weather motor  2  shown in  FIG. 2  and the all-weather motor  2  shown in  FIG. 5  can be assembled to upper and lower parts of the vehicle body frame of the unmanned aerial vehicle so that the attachment bases  10  face each other. As rotation directions of the propellers  3  (all-weather motors  2 ) are opposite to each other in this case, the motors are driven to be forwardly/reversely rotated, and motor vibrations acting on the vehicle body frame are opposite directions and cancel each other out; therefore, vibrations can be reduced even when the thrust is doubled. In the case where the all-weather motors  2  shown in  FIG. 2  and  FIG. 5  are attached to upper and lower parts through the vehicle body frame, air is taken in to respective rotation case bodies  4  from the intake openings  4   e  at the lower parts in the axial direction and is discharged from the discharge openings  4   f  at the upper side parts in the axial direction; therefore, the motor performance can be maintained by enhancing the dust-proof and drip-proof performance and preventing invasion of foreign matter and water. 
     Though the DC brushless motor is used for the above-described all-weather motor  2 , other motors such as a DC brush motor may be used. 
     Moreover, the fin  17  fixed to the rotating case body  4  by screw-fitting may be integrally formed with the rotating case body  4  (the first case body  4   a  or the second case body  4   b ). 
     Moreover, the intake openings  4   e  are preferably provided on a lower end surface in the axial direction in consideration of drip-proof properties in the case where the rotating case body  4  has a bottomed cylindrical body as described above; however, it is desirable that the intake openings  4   e  are provided on a lower surface in the axial direction in a case where the rotating case body  4  has curved surfaces not having an end surface. 
     Moreover, as the filter material  18 , various types of materials and forms such as a porous material made of resin and a metal mesh material as far as water repellency, breathability and dust-proof properties can be secured. 
     The case where the all-weather motor  2  is used as the driving source for the unmanned aerial vehicle has been explained in the above embodiments. However, applications are not limited to the above, and the all-weather motor  2  may be adopted as driving sources for other applications used outdoors.