Patent Publication Number: US-2021189686-A1

Title: Electric motor, rotary drive system, and hydraulic shovel

Description:
TECHNICAL FIELD 
     The present invention relates to an electric motor, a rotary drive system, and a hydraulic shovel. 
     Priority is claimed on Japanese Patent Application No. 2018-035842, filed on Feb. 28, 2018, the content of which is incorporated herein by reference. 
     BACKGROUND ART 
     PTL 1 discloses a hydraulic shovel provided with a rotary drive system swinging an upper swing body with respect to an undercarriage. The rotary drive system includes an electric motor and a speed reducer decelerating the rotation of the electric motor. The rotary drive system is provided with a brake for preventing inadvertent rotation in a stopped state. The brake includes a brake disk capable of rotating integrally with a rotary shaft and a brake piston pressing the brake disk. 
     Lubricating oil is supplied from the outside to the electric motor of the rotary drive system so that cooling capability is ensured for a rotor and a stator and lubricity is ensured for each sliding portion such as a bearing. The lubricating oil is supplied into the electric motor by a lubricating oil pump being driven. 
     CITATION LIST 
     Patent Literature 
     [PTL 1] Japanese Unexamined Patent Application, First Publication No. 2016-172965 
     DISCLOSURE OF INVENTION 
     Technical Problem 
     By the way, when the electric motor that is in a stopped state is started and the rotor rotates, lubricating oil is supplied into the electric motor by the lubricating oil pump being driven at the same time. However, there is a time difference between the driving of the lubricating oil pump and the lubricating oil reaching the sliding portion. In addition, viscosity of the lubricating oil is high at a low temperature in particular, and thus it takes time for the lubricating oil to reach the sliding portion. 
     The present invention has been made in view of such problems, and an object of the present invention is to provide an electric motor, a rotary drive system, and a hydraulic shovel allowing lubricating oil to be smoothly supplied to a sliding portion. 
     Solution to Problem 
     An electric motor according to an aspect of the present invention includes: a rotor including a rotary shaft that has an axis extending vertically and rotates around the axis and a rotor core fixed to an outer peripheral surface of the rotary shaft; a stator surrounding the rotor core from an outer peripheral side of the stator; a partition wall partitioning a first space where the rotor and the stator are disposed and lubricating oil is supplied from an outside; a storage portion configured to store the lubricating oil supplied into the first space; a drive unit discharging the lubricating oil inside the storage portion into the first space; and sliding portions into each of which the lubricating oil discharged from the inside of the storage portion is introduced. 
     According to the electric motor configured as described above, lubricity is ensured in the sliding portion by the lubricating oil supplied to the first space from the outside. In addition, the lubricating oil is introduced into the storage portion. As a result, lubricating oil is stored in the storage portion. 
     Additionally, in a case where it is difficult to supply lubricating oil from the outside to the first space, for example, the lubricating oil stored in the storage portion is discharged into the first space by the drive unit. The lubricating oil discharged in this manner lubricates the sliding portion by being introduced into the sliding portion. 
     Accordingly, it is possible to smoothly supply the lubricating oil discharged from the storage portion to the sliding portion even in a situation in which it is difficult to supply lubricating oil from the outside. 
     Advantageous Effects of Invention 
     According to the electric motor, the rotary drive system, and the hydraulic shovel of the above aspect, it is possible to smoothly supply lubricating oil to a sliding portion. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a side view of a hydraulic shovel including a rotary drive system according to a first embodiment of the present invention. 
         FIG. 2  is a plan view of the hydraulic shovel including the rotary drive system according to the first embodiment of the present invention. 
         FIG. 3  is a schematic diagram showing an outline of the rotary drive system according to the first embodiment of the present invention. 
         FIG. 4  is a longitudinal cross-sectional view of a rotary drive device in the rotary drive system according to the first embodiment of the present invention. 
         FIG. 5  is an enlarged view of the vicinity of a brake mechanism in  FIG. 4  and is a diagram showing a state where a brake piston is at a bottom dead center. 
         FIG. 6  is an enlarged view of the vicinity of the brake mechanism in  FIG. 4  and is a diagram showing a state where the brake piston is at a top dead center. 
         FIG. 7  is an enlarged view of a main portion of an electric motor of a rotary drive system according to a second embodiment of the present invention. 
     
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     First Embodiment 
     Hereinafter, a first embodiment of the present invention will be described in detail with reference to  FIGS. 1 to 6 . 
     &lt;Work Machine&gt; 
     As shown in  FIGS. 1 and 2 , a hydraulic shovel  200  as a work machine includes an undercarriage  210 , a swing circle  220 , and an upper swing body  230 . In the following description, the direction in which gravity acts in a state where the work machine is installed on a horizontal surface will be referred to as “vertical direction”. In addition, the front of the driver&#39;s seat in a cab  231  (described later) will be simply referred to as “front” and the rear of the driver&#39;s seat will be simply referred to as “rear”. 
     The undercarriage  210  includes a pair of left and right crawlers  211  and  211  and the hydraulic shovel  200  travels by the crawlers  211  and  211  being driven by a traveling hydraulic motor (not shown). 
     The swing circle  220  is a member interconnecting the undercarriage  210  and the upper swing body  230  and includes an outer race  221 , an inner race  222 , and a swing pinion  223 . The outer race  221  is supported by the undercarriage  210  and has an annular shape about a swing axis L extending so as to match the vertical direction. The inner race  222  is an annular member coaxial with the outer race  221  and is disposed inside the outer race  221 . The inner race  222  is supported so as to be rotatable relative to the outer race  221  around the swing axis L. The swing pinion  223  meshes with internal teeth of the inner race  222  and the inner race  222  rotates relative to the outer race  221  by the swing pinion  223  rotating. 
     The upper swing body  230  is disposed so as to be capable of swinging around the swing axis L with respect to the undercarriage  210  by being supported by the inner race  222 . The upper swing body  230  includes the cab  231 , a work equipment  232 , an engine  236  provided behind the cab  231  and the work equipment  232 , a generator motor  237 , a hydraulic pump  238 , an inverter  239 , a capacitor  240 , and a rotary drive system  1 . 
     The cab  231  is disposed on the front left side of the upper swing body  230  and is provided with the driver&#39;s seat for a worker. The work equipment  232  is provided so as to extend in front of the upper swing body  230  and includes a boom  233 , an arm  234 , and a bucket  235 . The work equipment  232  performs various works such as excavation by the boom  233 , the arm  234 , and the bucket  235  being respectively driven by hydraulic cylinders (not shown). 
     The shafts of the engine  236  and the generator motor  237  are spline-coupled. The generator motor  237  generates electric power by being driven by the engine  236 . The rotary shafts of the generator motor  237  and the hydraulic pump  238  are spline-coupled. The hydraulic pump  238  is driven by the engine  236 . Each of the hydraulic cylinders and the traveling hydraulic motor described above are driven by the hydraulic pressure that is generated by the hydraulic pump  238  being driven. 
     The generator motor  237 , the capacitor  240 , and the rotary drive system  1  are electrically interconnected via the inverter  239 . In addition, another electric power storage device such as a lithium-ion battery may be used instead of the capacitor  240 . 
     The rotary drive system  1  is disposed in a vertically disposed state where an axis O as a rotation center matches the vertical direction. The output of the rotary drive system  1  is transmitted to the swing pinion  223  meshing with the internal teeth of the inner race  222 . 
     The hydraulic shovel  200  drives the rotary drive system  1  with the electric power generated by the generator motor  237  or the electric power from the capacitor  240 . The drive force of the rotary drive system  1  is transmitted to the inner race  222  via the swing pinion  223 . As a result, the upper swing body  230  swings by the inner race  222  rotating relative to the outer race  221 . 
     When the swinging of the upper swing body  230  is decelerated, the rotary drive system  1  generates electric power as regenerative energy by functioning as a generator. This electric power is accumulated in the capacitor  240  via the inverter  239 . The electric power accumulated in the capacitor  240  is supplied to the generator motor  237  when the engine  236  is accelerated. The generator motor  237  assists the output of the engine  236  by the generator motor  237  being driven by the electric power of the capacitor. 
     &lt;Rotary Drive System&gt; 
     As shown in  FIG. 3 , the rotary drive system  1  includes a rotary drive device  10  and a lubricating oil circulation unit  150 . A speed reducer  60  is installed below an electric motor  20 . 
     &lt;Rotary Drive Device&gt; 
     As shown in  FIGS. 3 and 4 , the rotary drive device  10  includes the electric motor  20  and the speed reducer  60  provided integrally with the electric motor  20 . 
     &lt;Electric Motor&gt; 
     As shown in  FIGS. 3 and 4 , the electric motor  20  includes an electric motor casing  21 , a stator  30 , and a rotor  38 . 
     Further, the electric motor  20  includes a brake mechanism  120 . In the present embodiment, the brake mechanism  120  is accommodated in the speed reducer  60 . Accordingly, details of the brake mechanism  120  will be described in the description of the speed reducer  60 . 
     &lt;Electric Motor Casing&gt; 
     As shown in  FIG. 4 , the electric motor casing  21  is a member forming the outer shape of the electric motor  20 . The electric motor casing  21  includes an upper casing  22  and a lower casing  25 . 
     The upper casing  22  has a bottomed cylindrical shape having an upper cylindrical portion  23  that has a cylindrical shape and extends in the vertical direction (axis O direction) and an upper bottom portion  24  blocking the upper part of the upper cylindrical portion  23 . 
     The lower casing  25  has a bottomed cylindrical shape having a lower cylindrical portion  26  that has a cylindrical shape and extends in the vertical direction and a lower bottom portion  27  blocking the lower part of the lower cylindrical portion  26 . The lower bottom portion  27  is an example of the partition wall that vertically divides a first space R 1  and a second space R 2  (described later). 
     The lower bottom portion  27  serves as the bottom portion of the electric motor casing  21 . Specifically, as shown in  FIGS. 5 and 6 , the lower bottom portion  27  has a lower through hole  27   a  penetrating the lower bottom portion  27  about the axis O. The part that is around the lower through hole  27   a  on the surface of the lower bottom portion  27  facing upward is an annular first bottom surface  27   b  having a flat shape orthogonal to the axis O. A second bottom surface  27   c  formed one step higher than the first bottom surface  27   b  is formed on the outer peripheral side of the first bottom surface  27   b  of the lower bottom portion  27 . A plurality of the second bottom surfaces  27   c  may be divided in the circumferential direction. The first bottom surface  27   b  and the second bottom surface  27   c  are interconnected by a stepped portion  27   d  extending in the vertical direction. The outer peripheral side end portion of the second bottom surface  27   c  is connected to the inner peripheral surface of the lower cylindrical portion  26 . 
     The outer peripheral surface of the lower cylindrical portion  26  is fitted to the inner peripheral surface of the upper cylindrical portion  23  in such a manner that the lower cylindrical portion  26  is inserted into the upper cylindrical portion  23  from below. As a result, the lower cylindrical portion  26  and the upper cylindrical portion  23  are integrally fixed to each other. The space inside the electric motor casing  21  that is formed by the lower cylindrical portion  26  and the upper cylindrical portion  23  is the first space R 1 . 
     &lt;Communication Hole&gt; 
     Here, as shown in  FIGS. 5 and 6 , the electric motor casing  21  has a communication hole  50  allowing the first space R 1  in the electric motor casing  21  to communicate downward. 
     In the present embodiment, the communication hole  50  is formed so as to open to the first bottom surface  27   b  in the lower bottom portion  27  of the lower casing  25  and vertically penetrates the lower bottom portion  27 . A plurality of the communication holes  50  arc formed at intervals in the circumferential direction. 
     In addition, another communication hole may be formed at, for example, another part of the lower bottom portion  27 . Further, another communication hole vertically penetrating the lower cylindrical portion  26  may be formed. 
     &lt;Stator&gt; 
     As shown in  FIG. 4 , the stator  30  includes a stator core  31  and a coil  32 . 
     The stator core  31  is configured by a plurality of electromagnetic steel plates being stacked in the vertical direction and has a cylindrical shape about the axis O. The stator core  31  includes a yoke and a plurality of teeth formed at intervals in the circumferential direction of the yoke so as to protrude from the inner peripheral surface of the yoke. The stator core is fixed to the electric motor casing  21 . 
     A plurality of the coils  32  are provided so as to correspond to the respective teeth and wound around the respective teeth. As a result, the plurality of coils  32  are provided at intervals in the circumferential direction. The part of each coil  32  that protrudes upward from the stator core  31  is an upper coil end  32   a.  The part of each coil  32  that protrudes downward from the stator core  31  is a lower coil end  32   b.    
     &lt;Rotor&gt; 
     As shown in  FIG. 4 , the rotor  38  includes a rotary shaft  40 , a rotor core  42 , a lower end plate  45 , and an upper end plate  46 . 
     &lt;Rotary Shaft&gt; 
     The rotary shaft  40  is a rod-shaped member extending along the axis O. The rotary shaft  40  is disposed in the electric motor casing  21  so as to penetrate the inside of the stator  30  in the vertical direction. The upper end of the rotary shaft  40  protrudes above the upper bottom portion  24  in the upper casing  22 . In addition, the upper end of the rotary shaft  40  may be accommodated in the electric motor casing  21 . 
     The upper bottom portion  24  is provided with an upper seal  35  for sealing between the upper bottom portion  24  and the outer peripheral surface of the rotary shaft  40 . As a result, liquid tightness is ensured at the upper end inside the electric motor casing  21 . 
     &lt;Rotor Core&gt; 
     The rotor core  42  has a cylindrical shape about the axis O and an inner peripheral surface  42   a  is externally fitted on the outer peripheral surface of the rotary shaft  40 . The rotor core  42  is configured by a plurality of electromagnetic steel plates being stacked in the vertical direction. In the rotor core  42 , a plurality of permanent magnets (not shown) are embedded at intervals in the circumferential direction. 
     &lt;Lower End Plate&gt; 
     The lower end plate  45  is fixed so as to be stacked on the rotor core  42  from below the rotor core  42 . 
     &lt;Upper End Plate&gt; 
     The upper end plate  46  is fixed so as to be stacked on the rotor core  42  from above the rotor core  42 . 
     &lt;Intra-rotor Flow Path F&gt; 
     The rotor  38  has an intra-rotor flow path F extending downward from the upper end of the rotary shaft  40  and passing between the rotary shaft  40  and the rotor core  42 , through the lower end plate  45 , through the rotor core  42 , and through the upper end plate  46 . The intra-rotor flow path F is open from the upper surface of the upper end plate  46  into the first space R 1 . 
     &lt;Upper Bearing&gt; 
     The upper bottom portion  24  is provided with an upper bearing  36  having an annular shape about the axis O. The rotary shaft  40  is vertically inserted through the upper bearing  36  and the upper portion of the rotary shaft  40  is supported by the upper bearing  36  so as to be rotatable around the axis O. 
     &lt;Lower Bearing (Sliding Portion)&gt; 
     As shown in  FIGS. 5 and 6 , the lower through hole  27   a  in the lower bottom portion  27  is provided with a lower bearing  37  having an annular shape about the axis O. The lower bearing  37  is an example of a sliding portion. The rotary shaft  40  is vertically inserted through the lower bearing  37  and the lower portion of the rotary shaft  40  is supported by the lower bearing  37  so as to be rotatable around the axis O. The upper surface of the lower bearing  37  has the same height as the first bottom surface  27   b.  Lubricating oil introduced into the lower bearing  37  passes through the lower bearing  37  and falls downward. 
     &lt;Speed Reducer&gt; 
     Next, the speed reducer  60  will be described with reference to  FIG. 4 . The speed reducer  60  includes a speed reducer casing  61 , an output shaft  70 , and a transmission unit  80 . 
     &lt;Speed Reducer Casing&gt; 
     The speed reducer casing  61  has a cylindrical shape extending along the axis O and open upward and downward. The upper end of the speed reducer casing  61  abuts the electric motor casing  21  from below. The upper opening of the speed reducer casing  61  is blocked by the lower casing  25  of the electric motor casing  21 . 
     &lt;Output Shaft&gt; 
     The output shaft  70  has a rod shape extending along the axis O. The rotation of the output shaft  70  becomes the output of the rotary drive system  1 . The upper portion of the output shaft  70  is disposed in the speed reducer casing  61  and the lower portion of the output shaft  70  protrudes downward from the speed reducer casing  61 . An output shaft bearing  71  supporting the output shaft  70  so as to be rotatable around the axis O is provided below the inner peripheral surface of the speed reducer casing  61 . The lower portion of the output shaft  70  that protrudes downward from the speed reducer casing  61  is connected to the swing pinion  223 . 
     A lower seal  72  sealing the annular space between the inner peripheral surface of the speed reducer casing  61  and the outer peripheral surface of the output shaft  70  is provided further below the output shaft bearing  71  on the inner peripheral surface of the speed reducer casing  61 . The space in the speed reducer casing  61  that is blocked from below by the lower seal  72  is the second space R 2 . The lower portion of the rotary shaft  40  that protrudes downward from the electric motor casing  21  is positioned above the second space R 2 . Lubricating oil is stored up to a predetermined height position in the second space R 2 . In other words, the second space R 2  functions as a lubricating oil storage tank. 
     &lt;Transmission Unit&gt; 
     The transmission unit  80  is provided in the second space R 2  in the speed reducer casing  61 . The transmission unit  80  has a role of reducing the rotational speed of the rotary shaft  40  and transmitting the reduced rotational speed to the output shaft  70 . 
     The transmission unit  80  includes multi-stage planetary gear mechanisms sequentially reducing the rotational speed from the rotary shaft  40  to the output shaft  70 . In the present embodiment, the three planetary gear mechanisms of a first stage planetary gear mechanism  90 , a second stage planetary gear mechanism  100 , and a third stage planetary gear mechanism  110  are provided as the plurality of planetary gear mechanisms. In the present embodiment, at least one of the planetary gear mechanisms is immersed in the lubricating oil. 
     The first stage planetary gear mechanism  90  is a planetary gear mechanism disposed at a first stage. The first stage planetary gear mechanism  90  includes a first stage transmission shaft  91 , a first stage planetary gear  92 , and a first stage carrier  93 . The first stage transmission shaft  91  is externally fitted from the lower end to the lower portion of the rotary shaft  40 . The first stage transmission shaft  91  is rotatable around the axis O integrally with the rotary shaft  40 . Outer gear teeth are formed at a part of the outer peripheral surface of the first stage transmission shaft  91 . 
     A plurality of the first stage planetary gears  92  are provided at intervals in the circumferential direction around the first stage transmission shaft  91  so as to mesh with the outer gear teeth of the first stage transmission shaft. The first stage planetary gear  92  meshes with first stage inner gear teeth  62   a  formed on the inner peripheral surface of the speed reducer casing  61 . 
     The first stage carrier  93  supports the first stage planetary gear  92  so as to be capable of rotating and revolving around the axis O of the first stage transmission shaft  91 . 
     The second stage planetary gear mechanism  100  and the third stage planetary gear mechanism  110  are similar in configuration to the first stage planetary gear  92 . 
     The second stage planetary gear mechanism  100  includes a second stage transmission shaft  101 , a second stage planetary gear  102 , and a second stage carrier  103 . The second stage transmission shaft  101  is provided below the first stage transmission shaft  91  so as to be rotatable around the axis O and is connected to the first stage carrier  93 . The second stage planetary gear  102  meshes with second stage inner gear teeth  62   b  formed on the inner peripheral surface of the speed reducer casing  61 . 
     The third stage planetary gear mechanism  110  includes a third stage transmission shaft  111 , a third stage planetary gear  112 , and a third stage carrier  113 . The third stage transmission shaft  111  is provided below the second stage transmission shaft  101  so as to be rotatable around the axis O and is connected to the second stage carrier  103 . The third stage planetary gear  112  meshes with third stage inner gear teeth  62   c  formed on the inner peripheral surface of the speed reducer casing  61 . The third stage carrier is connected to the output shaft  70 . 
     The rotation of the rotary shaft  40  is transmitted to the output shaft  70  after being decelerated a plurality of times by the multi-stage planetary gear mechanisms. 
     &lt;Brake Mechanism (Drive Unit)&gt; 
     Next, the brake mechanism  120  as an example of a drive unit will be described with reference to  FIGS. 5 and 6 . 
     The brake mechanism  120  is disposed above the first stage planetary gear mechanism  90  in the second space R 2  of the speed reducer casing  61 . 
     The brake mechanism  120  includes a disk support portion  121 , a brake disk  122 , a brake plate  123 , a brake piston (piston)  130 , a seal portion  160 , a brake spring (spring)  140 , and a movement mechanism  170 . 
     &lt;Disk Support Portion&gt; 
     The disk support portion  121  is a cylindrical member about the axis O. The lower end of the disk support portion  121  is integrally fixed over the circumferential direction to the upper portion of the first stage carrier  93  in the first stage planetary gear mechanism  90 . The lower portion of the rotary shaft  40  and a part of the first stage transmission shaft  91  are positioned on the inner peripheral side of the disk support portion  121 . 
     &lt;Brake Disk&gt; 
     The brake disk  122  is an annular member and a plurality of the brake disks  122  (two brake disks  122  in the present embodiment) are disposed at intervals in the vertical direction so as to overhang from the outer peripheral surface of the disk support portion  121 . The brake disk  122  has a plate shape and the vertical direction is the plate thickness direction of the plate shape. 
     The brake disk  122  of the present embodiment is provided on the lower portion of the rotary shaft  40  via the disk support portion  121  and the first stage planetary gear mechanism  90 . The brake disk  122  may be directly fixed so as to overhang radially outward from the lower portion of the rotary shaft  40 . The brake disk  122  rotates about the axis O together with the rotary shaft  40 . In the present embodiment, the brake disk  122  rotates at a rotational speed reduced by one step by the first stage planetary gear mechanism  90  with respect to the rotational speed of the rotary shaft  40 . 
     &lt;Brake Plate&gt; 
     The brake plate  123  is an annular member and a plurality of the brake plates  123  (three brake plates  123  in the present embodiment) are disposed at intervals in the vertical direction so as to overhang from the inner peripheral surface of the speed reducer casing  61 . The brake plate  123  has a plate shape and the vertical direction is the plate thickness direction of the plate shape. The brake plate  123  is provided so as to overhang from a first sliding contact inner peripheral surface  64   a  on the inner peripheral surface of the speed reducer casing  61 . The first sliding contact inner peripheral surface  64   a  has an inner peripheral cylindrical surface shape about the axis O. 
     The plurality of brake plates  123  and the plurality of brake disks  122  are alternately disposed in the order of the brake plates  123  and the brake disks  122  downward from above. The brake plate  123  and the brake disk  122  are capable of abutting each other in the vertical direction. The outer peripheral end of the brake disk  122  faces the first sliding contact inner peripheral surface  64   a  at an interval and from the radially inner side. The inner peripheral end of the brake plate  123  faces the outer peripheral surface of the disk support portion  121  at an interval and from the radially outer side. 
     &lt;Brake Piston&gt; 
     The brake piston  130  is an annular member about the axis O and is disposed between the upper surface of the brake disk  122  and a lower surface  21   a  of the electric motor casing  21  in the second space R 2 . In the present embodiment, the brake plate  123  is interposed between the brake piston  130  and the upper surface of the brake disk  122 . The brake piston  130  is disposed so as to be movable in the vertical direction, which is a direction of advancing and retreating with respect to the electric motor casing  21 . In other words, the brake piston  130  is capable of reciprocating in the vertical direction. 
     An upper surface  130   a  of the brake piston  130  faces the lower surface  21   a  of the electric motor casing  21  from below. The lower portion of the outer peripheral surface of the brake piston  130  is a first sliding contact outer peripheral surface  131  having a circular cross-sectional shape orthogonal to the axis O. The first sliding contact outer peripheral surface  131  of the brake piston  130  is slidable in the vertical direction with respect to the first sliding contact inner peripheral surface  64   a  of the speed reducer casing  61 . A first O-ring  131   a  is provided between the first sliding contact outer peripheral surface  131  and the first sliding contact inner peripheral surface  64   a.  In the present embodiment, the first O-ring  131   a  is accommodated in a groove portion formed in the first sliding contact outer peripheral surface  131 . The first O-ring  131   a  is slidable in the vertical direction with respect to the first sliding contact inner peripheral surface  64   a.    
     The upper portion of the outer peripheral surface of the brake piston  130  is a second sliding contact outer peripheral surface  132  having a circular cross-sectional shape orthogonal to the axis O. The second sliding contact outer peripheral surface  132  is larger in outer diameter than the first sliding contact outer peripheral surface  131 . The second sliding contact outer peripheral surface  132  of the brake piston  130  is slidable in the vertical direction with respect to a second sliding contact inner peripheral surface  64   b  of the speed reducer casing  61 . The second sliding contact inner peripheral surface  64   b  of the speed reducer casing  61  is larger in inner diameter than the first sliding contact inner peripheral surface  64   a.  A second O-ring  132   a  is provided between the second sliding contact outer peripheral surface  132  and the second sliding contact inner peripheral surface  64   b.  In the present embodiment, the second O-ring  132   a  is accommodated in a groove portion formed in the second sliding contact outer peripheral surface  132 . The second O-ring  132   a  is slidable in the vertical direction with respect to the second sliding contact inner peripheral surface  64   b.    
     The step portion in the brake piston  130  that is between the first sliding contact outer peripheral surface  131  and the second sliding contact outer peripheral surface  132  is a pressure receiving surface  133  forming a flat shape orthogonal to the axis O, facing downward, and forming an annular shape. 
     The step portion in the speed reducer casing  61  that is between the first sliding contact inner peripheral surface  64   a  and the second sliding contact inner peripheral surface  64   b  is a stepped surface  64   c  forming a flat shape orthogonal to the axis O, facing upward, and forming an annular shape. 
     The pressure receiving surface  133  and the stepped surface  64   c  face each other in the vertical direction and approach and separate from each other as the brake piston  130  moves in the vertical direction. The annular space between the pressure receiving surface  133  and the stepped surface  64   c  is a hydraulic pressure supply space R 4 . In the hydraulic pressure supply space R 4 , liquid tightness is ensured by the first O-ring  131   a  and the second O-ring  132   a.  The volume of the hydraulic pressure supply space R 4  changes as the brake piston  130  moves in the vertical direction. 
     The speed reducer casing  61  has a hydraulic pressure supply hole  61   a  interconnecting the stepped surface  64   c  and the outside of the speed reducer casing  61 . The hydraulic pressure supply space R 4  communicates with the outside via the hydraulic pressure supply hole  61   a.    
     On an annular lower surface  130   b  of the brake piston  130 , a plate abutting surface  134  having an annular shape about axis O is formed so as to protrude from the lower surface  130   b.  The plate abutting surface  134  faces the brake plate  123  from above over the entire circumferential direction. 
     As shown in  FIG. 5 , in the brake piston  130 , the position where the plate abutting surface  134  abuts the brake plate  123  and the upper surface  130   a  is spaced downward from the lower surface  21   a  of the electric motor casing  21  is the bottom dead center of the reciprocating movement. 
     As shown in  FIG. 6 , in the brake piston  130 , the position where the plate abutting surface  134  is spaced upward from the brake plate  123  and the upper surface  130   a  abuts the lower surface  21   a  of the electric motor casing  21  is the top dead center of the reciprocating movement. 
     &lt;Storage Portion&gt; 
     The upper surface  130   a  of the brake piston  130  has a piston-side accommodation recessed portion  135  recessed downward from above. A plurality of the piston-side accommodation recessed portions  135  are disposed at intervals in the circumferential direction. The piston-side accommodation recessed portion  135  has a circular shape in a cross-sectional view orthogonal to the axis O. 
     The lower surface  21   a  of the electric motor casing  21  has a casing-side accommodation recessed portion  28  recessed upward from below. A plurality of the casing-side accommodation recessed portions  28  are disposed at intervals in the circumferential direction. The casing-side accommodation recessed portion  28  has a circular shape having the same inner diameter as the piston-side accommodation recessed portion  135  in a cross-sectional view orthogonal to the axis O. The casing-side accommodation recessed portion  28  is provided so as to correspond to the piston-side accommodation recessed portion  135 . In other words, each casing-side accommodation recessed portion  28  and each piston-side accommodation recessed portion  135  are provided at the same circumferential position so as to correspond to each other in a one-to-one relationship. The central axes of the corresponding casing-side accommodation recessed portion  28  and piston-side accommodation recessed portion  135  are coaxial. 
     A space defined by the casing-side accommodation recessed portion  28  and the piston-side accommodation recessed portion  135  is defined as a spring accommodation space R 3 . The spring accommodation space R 3  functions as a storage portion  180  in which lubricating oil is stored. The spring accommodation space R 3  communicates with the first space R 1  via a hole portion  29  formed in the lower bottom portion  27  of the electric motor casing  21 . The hole portion  29  penetrates the lower bottom portion  27  in the vertical direction. The opening on the upper side of the hole portion  29  is open to the second bottom surface  27   c  of the lower bottom portion  27 . As a result, the hole portion  29  is open toward the upper portion of the first space R 1 . 
     &lt;Seal Portion&gt; 
     An annular projecting portion  130   c  protruding annularly upward about the central axis O of the piston-side accommodation recessed portion  135  is formed around the piston-side accommodation recessed portion  135  in the upper surface  130   a  of the brake piston  130 . An annular recessed portion  27   e  recessed annularly upward about the central axis O of the casing-side accommodation recessed portion  28  is formed around the casing-side accommodation recessed portion  28  in the lower surface  21   a  of the electric motor casing  21 . 
     The outer peripheral surface of the annular projecting portion  130   c  and the inner peripheral surface of the annular recessed portion  27   e  have corresponding diameters. The outer peripheral surface of the annular projecting portion  130   c  is slidable in the vertical direction with respect to the inner peripheral surface of the annular recessed portion  27   e.  The upper end of the annular projecting portion  130   c  abuts the upper end of the annular recessed portion  27   e  when the brake piston  130  is positioned at the top dead center. 
     The seal portion  160  as an O-ring surrounding the spring accommodation space R 3  from the periphery is provided between the outer peripheral surface of the annular projecting portion  130   c  and the inner peripheral surface of the annular recessed portion  27   e.  In the present embodiment, the seal portion  160  is accommodated in the groove portion that is formed in the outer peripheral surface of the annular projecting portion  130   c.  The seal portion  160  abuts the inner peripheral surface of the annular recessed portion  27   e  regardless of whether the brake piston  130  is at the top dead center or the bottom dead center. As a result, the seal portion  160  liquid-tightly separates the spring accommodation space R 3  from the inside of the second space R 2 . 
     &lt;Brake Spring&gt; 
     The brake spring  140  is provided in the spring accommodation space R 3  and presses the brake piston  130  in a direction away from the electric motor casing  21 . 
     The brake spring  140  of the present embodiment is a coil spring and is disposed in a posture allowing expansion and contraction in the vertical direction in the spring accommodation space R 3 . The brake spring  140  is accommodated in a compressed state in the spring accommodation space R 3 . The upper end of the brake spring  140  abuts the bottom surface of the casing-side accommodation recessed portion  28  in the electric motor casing  21  and the lower end of the brake spring  140  abuts the bottom surface of the piston-side accommodation recessed portion  135  in the brake piston  130 . 
     In a state where no external force from the outside acts on the brake piston  130 , the brake piston  130  is at the bottom dead center position separated from the electric motor casing  21  by the pressing force of the brake spring  140  as shown in  FIG. 5 . The volume of the spring accommodation space R 3  is maximized at this time. 
     &lt;Movement Mechanism&gt; 
     The movement mechanism  170  moves the brake piston  130  upward so as to approach the electric motor casing  21  against the pressure of the brake spring  140 . The movement mechanism  170  includes a branch oil path  171 , an on-off valve  172 , and a controller  173 . 
     The branch oil path  171  is a flow path branching from a hydraulic circuit through which the hydraulic pressure generated by the hydraulic pump  238  discharging hydraulic oil flows. The branch oil path  171  is connected from the outside to the hydraulic pressure supply hole  61   a.    
     The branch oil path  171  is provided with the on-off valve  172 , which is a valve opening and closing the branch oil path  171 . The on-off valve  172  that is in a closed state prohibits hydraulic oil supply from the hydraulic circuit to the hydraulic pressure supply hole  61   a.  The on-off valve  172  that is in an open state allows hydraulic oil supply from the hydraulic circuit to the hydraulic pressure supply hole  61   a.    
     The controller  173  controls the opening and closing of the on-off valve  172 . 
     The controller  173  controls the on-off valve  172  such that the on-off valve  172  is opened by using, as an input, a lock release signal P that is output in response to a release operation of the swinging lock lever (lock lever) provided in the cab  231 . The on-off valve  172  is closed in a case where the swinging lock lever is in a lock state. The on-off valve  172  is opened only in a case where the swinging lock lever is in an unlock state. Accordingly, the hydraulic oil discharged by the hydraulic pump  238  is supplied to the hydraulic pressure supply hole  61   a  only in a case where a release operation of the swinging lock lever is performed and the swinging lock lever is in the unlock state. 
     The hydraulic oil introduced into the hydraulic pressure supply hole  61   a  reaches the hydraulic pressure supply space R 4 . Hydraulic pressure is generated by the hydraulic oil and an upward force resulting from the hydraulic pressure acts on the pressure receiving surface  133  of the brake piston  130  that defines the hydraulic pressure supply space R 4 . As a result, the brake piston  130  moves upward against the pressure of the brake spring  140 . The brake piston  130  moves to the top dead center by the hydraulic oil being supplied to the hydraulic pressure supply space R 4  as described above. The volume of the spring accommodation space R 3  is minimized at this time. 
     &lt;Lubricating Oil Circulation Unit&gt; 
     As shown in  FIG. 3 , the lubricating oil circulation unit  150  supplies lubricating oil into the first space R 1  in the electric motor casing  21  and re-supplies the lubricating oil collected from the inside of the second space R 2  in the speed reducer casing  61  into the first space R 1 . 
     The lubricating oil circulation unit  150  includes a lubricating oil flow path  151 , a lubricating oil pump  152 , a cooling unit  153 , and a strainer  154 . 
     The lubricating oil flow path  151  is a flow path formed by a flow path forming member such as piping provided outside the rotary drive device  10 . A first end of the lubricating oil flow path  151 , which is an upstream side end portion thereof, is connected to the second space R 2  in the speed reducer casing  61 . In the present embodiment, the first end of the lubricating oil flow path  151  is connected to the part in the second space R 2  that is between the output shaft bearing  71  and the lower seal  72 . 
     A second end of the lubricating oil flow path  151 , which is a downstream side end portion thereof, is connected to the opening of the intra-rotor flow path F at the upper end of the rotary shaft  40 . The second end of the lubricating oil flow path  151  is connected to the first space R 1  in the electric motor casing  21  via the intra-rotor flow path F. 
     The lubricating oil pump  152  is provided in the flow path of the lubricating oil flow path  151  and pumps lubricating oil from the first end toward the second end of the lubricating oil flow path  151 , that is, from the second space R 2  side toward the first space R 1  side. 
     The cooling unit  153  is provided at the part of the lubricating oil flow path  151  that is downstream of the lubricating oil pump  152 . The cooling unit  153  cools the lubricating oil that flows through the lubricating oil flow path  151  by heat exchange with the external atmosphere. 
     The strainer  154  is provided at the part of the lubricating oil flow path  151  that is upstream of the lubricating oil pump  152 . The strainer  154  has a filter removing dust and dirt from the lubricating oil that passes through the lubricating oil flow path  151 . It is preferable that the strainer  154  includes a magnetic filter removing, for example, iron powder generated from the gear teeth of the speed reducer  60 . 
     &lt;Action and Effect&gt; 
     When the engine  236  of the hydraulic shovel  200  is started, hydraulic pressure is generated by the hydraulic pump  238  being simultaneously driven. Then, by the swinging lock lever being released, the brake of the rotary shaft  40  of the rotary drive system is released and the rotary shaft becomes rotatable. 
     The brake piston  130  of the brake mechanism  120  is pressed downward by the brake spring  140 . As shown in  FIG. 5 , in a case where the swinging lock lever is in the lock state, the on-off valve  172  in the movement mechanism  170  of the brake mechanism  120  is closed and no hydraulic oil is supplied to the hydraulic pressure supply space R 4 . Accordingly, the brake piston  130  presses the brake disk  122  via the brake plate  123  in a state of being positioned at the bottom dead center. At this time, the rotary shaft  40  is in a non-rotatable brake state by the frictional force between the brake plate  123  and the brake disk  122 . 
     Then, the lock release signal P is input to the controller  173  of the movement mechanism  170  when a release operation for shifting the swinging lock lever from the lock state to the unlock state is performed. As a result, the controller  173  controls the on-off valve  172  from the closed state to the open state. By the on-off valve  172  being opened, hydraulic oil is supplied and hydraulic pressure is generated in the hydraulic pressure supply space R 4 . Then, the brake piston  130  that has received the hydraulic pressure on the pressure receiving surface  133  moves upward and is positioned at the top dead center. Accordingly, the pressing of the brake plate  123  and the brake disk  122  by the brake piston  130  is released and the rotary shaft  40  is put into a rotatable brake release state. 
     Then, the rotary drive system  1  is driven and the upper swing body  230  swings by the swinging lever in the cab  231  being operated. 
     In other words, when the swinging lever is operated, alternating current electric power is supplied to each coil  32  of the stator  30  of the electric motor  20  via the inverter  239  and the rotor  38  rotates with respect to the stator  30  by each permanent magnet following the rotating magnetic field that is generated by the coils  32 . The rotation of the rotary shaft  40  of the rotor  38  is decelerated via the transmission unit  80  in the speed reducer  60  and transmitted to the output shaft  70 . In the present embodiment, the deceleration is sequentially performed via the three-stage planetary gear mechanisms. The swinging operation of the upper swing body  230  is performed by the rotation of the output shaft  70 . 
     The electric motor  20  is driven with high torque when the upper swing body  230  swings. Accordingly, the temperatures of the rotor core  42  and the permanent magnet rise due to the iron loss in the rotor core  42  and the eddy current loss in the permanent magnet. At the same time, the temperature of the stator  30  rises due to the copper loss in the coil  32  and the iron loss in the stator core  31 . When the temperature of the stator  30  is high, the temperature of the rotor core  42  becomes higher due to the radiant heat of the stator  30 . Accordingly, cooling oil is supplied into the electric motor  20  by the lubricating oil circulation unit  150 . 
     When the swinging lever is operated, the lubricating oil pump  152  of the lubricating oil circulation unit  150  is driven together with the drive of the electric motor  20 . As a result, the lubricating oil stored by the second space R 2  being used as a tank is partially introduced into the intra-rotor flow path F of the electric motor  20  via the lubricating oil flow path  151 . The lubricating oil cools the rotor core  42  and the permanent magnets in the course of flowing through the intra-rotor flow path F. Then, the lubricating oil discharged from the rotor  38  to the first space R 1  in the electric motor casing  21  is sprayed radially outward by the centrifugal force resulting from the rotation of the rotor  38  and cools the coil  32  and the stator core  31 . 
     Subsequently, the lubricating oil that has fallen in the first space R 1  passes through the communication hole  50  penetrating the lower bottom portion  27  of the electric motor casing  21  or passes through the lower bearing  37 . Then, the lubricating oil is introduced into the second space R 2  in the speed reducer casing  61 . The lubricating oil passes through the lower bearing  37  and thus lubricity is ensured in the lower bearing  37 . 
     The lubricating oil introduced into the second space R 2  merges with the lubricating oil stored by the second space R 2  being used as a tank. In the second space R 2 , each planetary gear mechanism is lubricated by the lubricating oil falling from the electric motor casing  21  or by the stored lubricating oil. 
     In addition, the cooling mechanism of the electric motor  20  is not limited to the configuration described above and various configurations can be adopted. 
     Here, as described above, the lubricating oil pump  152  is started at the same time when the electric motor  20  is started. The lubricating oil that is supplied as a result ensures lubricity in the lower bearing  37 . However, in a case where the external atmosphere has a low temperature or the like, it takes time for the lubricating oil that has passed through the intra-rotor flow path F to reach the lower bearing  37  due to an increase in the viscosity of the lubricating oil. As a result of the situation in which it is difficult to supply lubricating oil to the lower bearing  37 , the rotary shaft  40  may rotate in a state where the lower bearing  37  is not lubricated. 
     Here, the spring accommodation space R 3  of the present embodiment is open toward the upper portion of the first space R 1 . Accordingly, when the rotary drive system  1  is operated and the lubricating oil pump  152  is driven, lubricating oil is introduced into the spring accommodation space R 3  via the hole portion  29 . In other words, the lubricating oil that flows down from the stator  30  and the rotor  38  is partially stored in the spring accommodation space R 3 . The spring accommodation space R 3  is filled with the lubricating oil even after the operation of the hydraulic shovel  200  is ended. 
     Then, when the operation of the hydraulic shovel  200  is started again and the release operation of the swinging lock lever is performed, hydraulic pressure is applied to the brake piston  130  and the brake piston  130  moves from the bottom dead center to the top dead center. As a result of this movement, the volume of the spring accommodation space R 3  defined by the brake piston  130  and the electric motor casing  21  decreases. As a result, the lubricating oil stored in the spring accommodation space R 3  is partially discharged into the first space R 1  via the hole portion  29 . By the lubricating oil discharged into the first space R 1  as described above being introduced into the lower bearing  37 , it is possible to lubricate the lower bearing  37  while the electric motor  20  and the lubricating oil pump  152  are driven. Accordingly, in a case where the electric motor  20  and the lubricating oil pump  152  are driven at the same time, it is possible to lubricate the lower bearing  37  in advance even in a case where lubricating oil supply to the lower bearing  37  is delayed. 
     As described above, according to the present embodiment, it is possible to discharge the lubricating oil stored in the spring accommodation space R 3  into the first space R 1  by input from the outside. The lubricating oil discharged in this manner is introduced into the lower bearing  37  and it is possible to lubricate the lower bearing  37  as a result. 
     Accordingly, it is possible to smoothly supply the lubricating oil discharged from the spring accommodation space R 3  to the lower bearing  37  as a sliding portion even in a situation in which it is difficult to supply lubricating oil from the outside. 
     The spring accommodation space R 3  is defined by the electric motor casing  21  and the brake piston  130  and used as the storage portion  180  in which lubricating oil is stored. Accordingly, it is possible to make compact the configuration of the mechanism itself that is capable of supplying lubricating oil to the first space R 1 . 
     In the present embodiment, the drive unit that is capable of discharging lubricating oil into the first space R 1  is configured by means of the brake mechanism  120  capable of braking the rotation of the rotary shaft  40  and releasing the braking. In other words, it is possible to realize a configuration in which both the brake mechanism  120  and a lubricating oil discharge mechanism are used together, and thus there is no need to provide separate mechanisms and it is possible to avoid an increase in device complexity. 
     The spring accommodation space R 3  is defined by the casing-side accommodation recessed portion  28  recessed from the lower surface  21   a  of the electric motor casing  21  and the piston-side accommodation recessed portion  135  recessed from the upper surface  130   a  of the brake piston  130 , and thus there is no need to separately provide a member for forming the spring accommodation space R 3 . In addition, the spring accommodation space R 3  is configured to be accommodated in the electric motor casing  21  and the brake piston  130 , and thus it is possible to make compact the entire device. 
     The spring accommodation space R 3  is isolated from the outside by the seal portion  160 , and thus it is possible to store reliably lubricating oil in the spring accommodation space R 3 . 
     In particular, in the present embodiment, the electric motor  20  and the speed reducer  60  has a unified lubrication system and the electric motor  20  is provided with no tank. Accordingly, the lower bearing  37  is not immersed in lubricating oil and the lubricity of the lower bearing  37  depends on the lubricating oil that is supplied from the outside and flows. In the present embodiment, it is possible to ensure the lubricity of the lower bearing  37  by the lubricating oil discharged from the spring accommodation space R 3  even in a case where it is difficult for the lubricating oil that is supplied from the outside to reach the lower bearing  37  under the situation described above. 
     In the present embodiment, the hydraulic pump  238  is driven by the rotation of the engine  236  and hydraulic pressure is generated as a result. Then, the brake of the rotary shaft  40  is released by the swinging lock lever being released and it is possible to discharge lubricating oil from the spring accommodation space R 3  to the first space R 1  at the same time. Accordingly, it is possible to reliably guide lubricating oil to the lower bearing  37  before the rotary shaft  40  rotates. 
     In addition, lubricating oil may be discharged from the spring accommodation space R 3  by a lock operation and unlock operation of the swinging lock lever during, for example, not only the operation of the hydraulic shovel  200  but also the start of the operation of the hydraulic shovel  200 . In this manner, lubricating oil is discharged vigorously, and thus it is possible to cool, for example, the lower coil end  32   b  of the stator positioned above the hole portion  29 . 
     Second Embodiment 
     Next, a rotary drive system  1 A according to a second embodiment of the present invention will be described with reference to  FIG. 7 . In the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals and detailed description thereof is omitted. 
     A storage portion  180 A of the rotary drive system IA of the second embodiment is provided in the first space R 1 . In other words, the storage portion  180 A is provided below the lower coil end  32   b  in the first space R 1 . The storage portion  180 A has a box shape with an upper opening and lubricating oil is introduced from above via the opening portion. 
     The rotary drive system  1 A of the second embodiment includes a drive unit  181  discharging the lubricating oil in the storage portion  180 A into the first space R 1  in response to input from the outside. The drive unit  181  has piping  182  having one end open to the storage portion  180 A and the other end open to the first space R 1 . The other end of the piping  182  is preferably open downward above, for example, the lower bearing  37  serving as a sliding portion. 
     The drive unit  181  includes the on-off valve  172  disposed in the pipeline of the piping  182 . The on-off valve  172  is configured to be opened and closed by the controller  173  similar to the controller  173  of the first embodiment. 
     When the rotary drive system  1 A is operated, lubricating oil falling from above is introduced into the storage portion  180 A via the opening. As a result, the lubricating oil is stored in the storage portion  180 A. 
     Then, the controller  173  opens the on-off valve  172  that is closed based on input from the outside as in the first embodiment. As a result, the lubricating oil in the storage portion  180 A is discharged into the first space R 1  via the piping. It is possible to lubricate the lower bearing  37  by the lubricating oil discharged in this manner. 
     Another Embodiment 
     Although the embodiments of the present invention have been described above, the present invention is not limited thereto and can be appropriately changed without departing from the technical idea of the present invention. 
     Although the lock release signal P output as the swinging lock lever is released is input to the controller  173  of the movement mechanism  170  in the embodiments, the present invention is not limited thereto. For example, a configuration in which lubricating oil in the storage portion  180  and  180 A is discharged into the first space R 1  by a signal output by a switch provided in the cab  231  may be adopted. In addition, a configuration in which lubricating oil is discharged into the first space R 1  in conjunction with the operation of an existing switch provided in the hydraulic shovel  200  may be adopted. 
     The configuration of the movement mechanism  170  is not limited to the first and second embodiments and another configuration may be adopted insofar as lubricating oil can be discharged into the first space R 1  in response to input from the outside. For example, a configuration in which lubricating oil can be discharged by an actuator being driven in response to a signal from the outside may be adopted. 
     Described in the first embodiment is an example in which the spring accommodation space R 3  as the storage portion  180  is defined by the casing-side accommodation recessed portion  28  of the electric motor casing  21  and the piston-side accommodation recessed portion  135  of the brake piston  130 . However, the present invention is not limited thereto and the spring accommodation space R 3  may be formed by a recessed portion formed in one of the electric motor casing  21  and the brake piston  130 . 
     The seal portion  160  sealing the spring accommodation space R 3  as the storage portion  180  is not limited to the configuration of the embodiment and another configuration may be adopted. Examples thereof include a seal portion such as an O-ring provided between the upper surface  130   a  of the brake piston  130  and the lower surface  21   a  of the electric motor casing  21 . 
     The lubricating oil storage portion  180  may be formed separately from the spring accommodation space R 3 . 
     The drive unit discharging lubricating oil may be configured by means of a simple piston that has no brake function instead of the brake piston  130 . 
     Although an example in which the lower bearing  37  is a sliding portion has been described in the embodiment, discharged lubricating oil may be guided to another sliding portion in another configuration. 
     In the embodiment, the on-off valve  172  is controlled from the closed state to the open state via the controller  173  when the swinging lock lever is released. However, the present invention is not limited thereto. For example, in another configuration, hydraulic oil may be supplied to the branch oil path  171  by the on-off valve  172  being directly opened from the closed state by the swinging lock lever being operated. In addition, the on-off valve  172  may be opened from the closed state in a case where various operation lever operations including the operation on the upper swing body  230  are performed. 
     Although an example in which the present invention is applied to the rotary drive system  1  and  1 A of the hydraulic shovel  200  as a work machine has been described in the embodiments, the present invention may be applied to the rotary drive system  1  and  1 A as a mechanism swinging or rotating a part of another work machine. 
     The present invention may be applied to an electric motor alone as well as the rotary drive system  1  and  1 A including the electric motor  20  and the speed reducer  60  and a configuration in which the electric motor  20  and a hydraulic motor driven by hydraulic pressure are combined may be applied. 
     INDUSTRIAL APPLICABILITY 
     According to the electric motor, the rotary drive system, and the hydraulic shovel of the above aspect, it is possible to smoothly supply lubricating oil to a sliding portion. 
     REFERENCE SIGNS LIST 
       1 : Rotary drive system 
       1 A: Rotary drive system 
       10 : Rotary drive device 
       20 : Electric motor 
       20 A: Electric motor 
       21 : Electric motor casing 
       21   a:  Lower surface 
       22 : Upper casing 
       23 : Upper cylindrical portion 
       24 : Upper bottom portion 
       24   a:  Upper through hole 
       25 : Lower casing 
       26 : Lower cylindrical portion 
       27 : Lower bottom portion (partition wall) 
       27   a:  Lower through hole 
       27   b:  First bottom surface 
       27   c:  Second bottom surface 
       27   d:  Stepped portion 
       27   e:  Annular recessed portion 
       28 : Casing-side accommodation recessed portion (recessed portion) 
       29 : Hole portion 
       30 : Stator 
       31 : Stator core 
       32 : Coil 
       32   a:  Upper coil end 
       32   b:  Lower coil end 
       35 : Upper seal 
       36 : Upper bearing 
       37 : Lower bearing (sliding portion) 
       38 : Rotor 
       40 : Rotary shaft 
       42 : Rotor core 
       45 : Lower end plate 
       46 : Upper end plate 
       50 : Communication hole 
       60 : Speed reducer 
       61 : Speed reducer casing 
       61   a:  Hydraulic pressure supply hole 
       62   a:  First stage inner gear teeth 
       62   b:  Second stage inner gear teeth 
       62   c:  Third stage inner gear teeth 
       64   a:  First sliding contact inner peripheral surface 
       64   b:  Second sliding contact inner peripheral surface 
       64   c:  Stepped surface 
       70 : Output shaft 
       71 : Output shaft bearing 
       72 : Lower seal 
       80 : Transmission unit 
       90 : First stage planetary gear mechanism 
       91 : First stage transmission shaft 
       92 : First stage planetary gear 
       93 : First stage carrier 
       100 : Second stage planetary gear mechanism 
       101 : Second stage transmission shaft 
       102 : Second stage planetary gear 
       103 : Second stage carrier 
       110 : Third stage planetary gear mechanism 
       111 : Third stage transmission shaft 
       112 : Third stage planetary gear 
       113 : Third stage carrier 
       120 : Brake mechanism (drive unit) 
       121 : Disk support portion 
       122 : Brake disk 
       123 : Brake plate 
       130 : Brake piston 
       130   a:  Upper surface 
       130   b:  Lower surface 
       130   c:  Annular projecting portion 
       131 : First sliding contact outer peripheral surface 
       131   a:  First O-ring 
       132 : Second sliding contact outer peripheral surface 
       132   a:  Second O-ring 
       133 : Pressure receiving surface 
       134 : Plate abutting surface 
       135 : Piston-side accommodation recessed portion (recessed portion) 
       140 : Brake spring 
       150 : Lubricating oil circulation unit 
       151 : Lubricating oil flow path 
       152 : Lubricating oil pump 
       153 : Cooling unit 
       154 : Strainer 
       160 : Seal portion 
       170 : Movement mechanism 
       171 : Branch oil path 
       172 : On-off valve 
       173 : Controller 
       180 : Storage portion 
       180 A: Storage portion 
       181 : Drive unit 
       182 : Piping 
       200 : Hydraulic shovel 
       211 : Crawler 
       210 : Undercarriage 
       220 : Swing circle 
       221 : Outer race 
       222 : Inner race 
       223 : Swing pinion 
       230 : Upper swing body 
       231 : Cab 
       232 : Work equipment 
       233 : Boom 
       234 : Arm 
       235 : Bucket 
       236 : Engine 
       237 : Generator motor 
       238 : Hydraulic pump 
       239 : Inverter 
       240 : Capacitor 
     L: Swing axis 
     O: Axis 
     S: Liquid surface 
     R 1 : First space 
     R 2 : Second space 
     R 3 : Spring accommodation space 
     R 4 : Hydraulic pressure supply space 
     F: Intra-rotor flow path 
     P: Lock release signal