JP2007295757A - Rotary electric machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce a defective fraction involved in mounting work while facilitating work related to the mounting of a ground terminal. <P>SOLUTION: A rotary electric machine is provided with a hollow cylindrical housing 14, a stator 16 fixed at the outer periphery of the housing 14, a bearing 18 fixed at the outer periphery of the housing 14, a rotor 20 arranged outside the stator 16 while being freely rotatably connected to the bearing 18, and a motor output shaft 22 connected to the rotor 20. A groove 32 having a nearly U-shaped cross-section is formed at the axial end of the housing 14. A tap hole 34 is formed at the axial end face 32a of the groove 32 along the axial direction. The ground terminal 38 is fixed to the tap hole 32 by fastening a tap screw 36. Grounding wiring 44 connected to the ground terminal 38 is led out to the outside of the housing 14 together with feeder wiring. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a rotating electrical machine, and more particularly to an improvement in the wiring structure of an abduction type rotating electrical machine in which a stator is located on the inner periphery and a rotor is located on the outer periphery.

  Conventionally, as a rotating electrical machine, for example, a stator fixed to the outer periphery of a hollow cylindrical housing, a bearing fixed to the outer periphery of the housing, a rotor rotatably connected to the bearing and disposed outside the stator, An external rotation type motor (motor) having an output shaft connected to a rotor, directly supporting a load without using a spindle, gears, etc., and applying a direct rotational driving force to the load is known. It is used for work rotation holding parts of machine tools, drive joints of robots, and the like. This type of abduction motor has a hollow hole structure that is as large as possible due to the characteristics of the device that directly drives the load, and wiring, piping, auxiliary shafts, etc. to the load are inserted into the hollow portion of the housing. It is required that the outer diameter of the device is as small as possible and the axial height thereof is low.

  That is, in order to increase the motor output as much as possible within a limited volume, it is necessary to make the outer periphery of the stator as large as possible, and conversely, make the inner periphery as small as possible. Furthermore, the outer diameter of the housing that does not directly contribute to the motor output needs to be as small as possible. For the same reason, it is necessary to make the wiring lead-out portion as small as possible.

  On the other hand, an external rotation type motor may be provided with a protective ground terminal for the purpose of improving safety. When the protective ground terminal is fixed inside the motor, it is desirable to use a bolt of M3 size or larger in order to satisfy the mechanical strength of the terminal and the prevention of screw loosening due to vibration. In this case, for example, a width of 5.5 mm or more is required as a space for fastening a terminal (crimp terminal) having a 3 mm hole and a M3 bolt inside the motor.

  Further, when the protective ground terminal is provided inside the motor, conventionally, as shown in FIG. 4, the flat end 72 is formed by cutting the axial end (outer cylindrical portion) of the housing 70 formed in a hollow cylindrical shape, A tapped hole 74 is formed in the plane 72 perpendicular to the axial direction, and a bolt 76 is fastened to the tapped hole 74 to fix the protective grounding terminal 78 to the flat surface 72 and connect to the protective grounding terminal 78 for grounding. A structure is adopted in which the wiring 80 is pulled out from the housing together with a power supply wiring (not shown).

Further, when fixing the protective ground terminal inside the motor, for example, the ground terminal is fixed to a bracket for closing the opening of the body case formed in a cylindrical shape, and the grounding wire connected to the ground terminal is connected to the main body. There has been proposed one that is drawn out together with a feeding wire from a cable drawing hole of the case (see Patent Document 1).
JP-A-6-315240

  In order to fix the protective grounding terminal 78 inside the motor, a tap hole 74 is formed in a plane 72 formed at the axial end of the housing 70 perpendicular to the axial direction, and a bolt 76 is fastened to the tap hole 74. In the structure in which the protective ground terminal 78 is fixed to the flat surface 72, when there is no need to form another hole in the flat surface 72 of the housing 70 other than the tap hole 74 for fixing the protective ground terminal 78, the tap hole 74. In order to form the workpiece, a setup time for setting the workpiece in the vertical direction is required. Moreover, there is a concern that the change in setup may cause a reduction in component accuracy.

  Further, in addition to the grounding wiring 80, there are motor windings, power supply wirings, and the like in the vicinity of the tap holes 74 formed in the plane 72. Therefore, tightening work with a tool (wrench) immediately above these wirings. Doing so may inadvertently damage motor windings and power supply wiring, leading to an increase in product defect rate. Moreover, since the tap hole 74 is formed in the plane 72 formed in the vertical direction, a space 82 for providing the protective ground terminal 78 must be provided along the axial direction of the housing 70, and the protective ground terminal 78. It is necessary to make the tap position (bolt position) for installing the motor higher than the coil end of the motor winding, which leads to an increase in the axial height (overall height) of the motor and hinders downsizing of the motor. It was.

  The present invention has been made in view of the above-described problems of the prior art, and an object thereof is to facilitate work related to attachment of a ground terminal and to reduce a defect rate associated with the attachment work.

  In order to achieve the above object, the present invention comprises a substantially hollow cylindrical housing, a stator fixed to the outer periphery of the housing, a bearing fixed to the outer periphery of the housing, and a bearing rotatably connected to the bearing. A rotor disposed outside the stator, and the housing is disposed concentrically with the rotor, and a groove having a substantially U-shaped cross section is formed at an axial end portion of the housing. An axial end surface is formed along the axial center of the housing, and an attachment hole is formed in the axial end surface of the groove along the axial direction. A grounding terminal is fixed to the attachment hole by fastening a fastening member. The rotating electrical machine is configured such that a grounding wire connected to the grounding terminal is drawn out from the housing together with a power feeding wire.

  According to the above-described means, when the grounding terminal mounting portion is processed in the housing, a groove is formed in the axial end portion of the housing, and thereafter, the mounting is performed on the axial end surface of the groove without changing the rotational axis direction of the blade. Since the hole is formed, for example, even when the rotary axis of the blade is processed by an inexpensive machine tool in one direction, after the groove is formed, the mounting hole can be tapped without changing the workpiece. It becomes possible. It is possible to reduce processing setup time and parts processing costs. Furthermore, when fastening a fastening member for fixing the grounding terminal to a mounting hole formed in the axial end surface of the groove of the housing, a tool for tightening the fastening member, for example, a wrench is operated along the axial direction of the housing. Therefore, when the fastening member is fastened, there is little risk of damaging the grounding wiring and the power feeding wiring, and it is possible to contribute to quality improvement as the defect rate decreases.

  When configuring the rotating electrical machine, at least one opening continuous with the axial end surface of the groove is formed adjacent to the axial end surface of the groove, or a part of the ground terminal is accommodated in the opening. Can be. In this case, the ground terminal can be prevented from jumping out from the outer periphery of the housing.

  According to the present invention, work related to ground terminal mounting can be facilitated, the defect rate associated with the mounting work can be reduced, and the processing setup time and parts processing costs can be reduced and the quality can be improved. Can do.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of an abduction motor showing one embodiment of the present invention. In FIG. 1, an outer rotation type electric motor 10 is a rotating electric machine, a boss member 12 formed in a substantially cylindrical shape, and a hollow cylindrical housing 14 arranged concentrically with the boss member 12 and fixed to the boss member 12. A stator 16 fixed to the outer periphery of the housing 14, a bearing 18 fixed to the outer periphery of the housing 14, a rotor 20 rotatably connected to the bearing 18 and disposed outside the stator 16, and a substantially cylindrical shape. And a motor output shaft 22 having an axial end connected to the rotor 20.

  The stator 16 includes a stator core 24 formed by laminating a plurality of steel plates into an annular shape, and a motor for forming a rotating magnetic field is formed on the plurality of teeth (not shown) formed on the stator core 24. Coils 26 are wound as windings.

  The rotor 20 arranged with a certain gap from the stator 16 is fixed to a rotor core (rotor yoke) 28 formed in a cylindrical shape using a magnetic material and to the inner peripheral side of the rotor core 28, and relative to each coil 26. A plurality of magnets 30 are provided so as to face each other.

  On the other hand, the housing 14 is arranged concentrically with the motor output shaft 22, and a groove 32 is formed in the axial end of the housing 14 by milling as shown in FIGS. 2 and 3. It is formed along the axial center of the housing 14 from 14a. A tap hole 34 as an attachment hole is formed in the axial end surface 32a of the groove 32 along the axial direction. A tap hole 34 and a tap screw (bolt) 36 are formed in the tap hole 34 and the axial end surface 32a. As a result, the ground terminal 38 is fixed.

  The groove 32 is U-shaped in cross section, and has a bottom surface on the axial center side of the housing 14 and an opening on the upper surface side, and extends from the axial end surface (motor mounting surface) 14a of the housing 14 to the axial center of the housing 14. It is formed along (along the axial direction). The diameter of the groove 32 is set to be equal to or larger than the diameter of the M3 tap screw (bolt) 36 in consideration of using the M3 tap screw (bolt) 36 as a fastening member fastened to the tap hole 34. .

  A plurality of openings 40 and 42 are formed in the axial end face 32a of the groove 32 so as to be adjacent to the axial end face 32a. The openings 40 and 42 are formed as flat surfaces exposed on the outer periphery of the housing 14, and at least one of the openings 40 and 42, for example, the opening 40 has a part of the ground terminal 38 and a ground terminal. A part of the grounding wiring 44 connected to 38 is accommodated.

  Further, in the outer rotation type electric motor 10 in this embodiment, a rotation sensor 46 is disposed on the outer peripheral side of the boss member 12 connected to the housing 14 as an outer rotor type brushless motor. The rotation sensor 46 is provided corresponding to, for example, the U, V, and W phases, and responds to a change in the magnetic poles of the resolver rotor 48 accompanying the rotation of the motor output shaft 22 and the rotor 20, and the motor output shaft 22 and the rotor 20. The rotation position of is detected.

  Further, the grounding wiring 44 is drawn out from the axial end portion of the housing 14 to the outside of the abduction motor 10 together with a power feeding wiring (not shown) for energizing the coil 26.

  Here, in the outer rotation type electric motor 10, the hollow hole diameter (inner diameter) of the housing 14 is φA, the outer diameter of the motor mounting surface 14 a among the outer diameters of the housing 14 is φB, and the outer diameter of the rotor 20 that is the motor outermost diameter. When the outer diameter is φC and the inner diameter of the bearing 18 is φD, φA = φD / (1.38 to 1.44), φB = φD ± 2, and φC−φB = contributing to the motor output. Motor portion, φB−φA = wiring space (wiring space for grounding wiring 44 and power supply wiring) is set.

  That is, the housing 14 has a hollow hole diameter φA that is 38% to 44% less than the inner ring of the bearing 18 and a motor mounting surface (outer diameter / bolt hole) 14b that has an inner ring inner diameter ± 2 mm of the bearing 18. ing. For this reason, the dimension of the radial direction of the housing 14 which does not contribute to a motor output can be made the smallest. As a result, the external rotation motor 10 can increase the hollow hole diameter φA of the housing 14 as much as possible, and the outer rotation motor in which the coil (coil winding portion) 26 of the stator 16 is effectively arranged as far as possible to the inner peripheral side of the housing 14. Type motor.

  According to the present embodiment, the rotation axis of the blade is only in one direction (a direction parallel to the axial direction of the housing 14). Therefore, when the grounding terminal mounting portion is formed by milling the housing 14, the shaft of the housing 14 is used. Since the tapping of the tapped hole 32a together with the groove 32 at the end portion in the direction only needs to be replaced with a blade, it is not necessary to replace the workpiece, and continuous machining can be performed, so the machining setup time and parts machining costs can be reduced. As well as improving the accuracy of parts (thinning). If milling is performed using a tool for machining the two openings 40 and 42 having a height in the axial direction equal to or less than the height of the openings 40 and 42, the openings 40 and 42 are also formed into the grooves 32. Along with the tap holes 32a, continuous machining is possible without changing the workpiece.

  Further, according to the present embodiment, when the tap screw (bolt) 36 for fixing the ground terminal 38 is fastened to the tap hole 34 formed in the axial end surface 32a of the groove 32 of the housing 14, the tap screw As a tool for tightening the (bolt) 36, for example, a wrench may be operated along the axial direction of the housing 14, so that there is a risk of damaging the ground wiring 44 and the power supply wiring when the tap screw (bolt) 36 is fastened. There are few, and it can contribute to the improvement of quality with the fall of a defective rate.

  Furthermore, according to the present embodiment, even when the ground terminal 38 is attached to the housing 14, the overall height of the motor can be further reduced, which can contribute to the downsizing of the abduction motor 10.

  Further, according to the present embodiment, since the openings 40 and 42 are provided, when the ground terminal 38 is attached, the opening 40 or 42 (40 in the present embodiment) is used to obtain a plane. As viewed (see FIG. 2), substantially the entire ground terminal 38 can be accommodated in the outer circumference of the housing 14, and the protrusion can be kept to a minimum.

  In the present embodiment, the openings 40 and 42 are provided so that the ground terminal 38 is accommodated in this portion to minimize the protruding portion. Only one of them may be provided. Furthermore, when allowing the ground terminal 38 to protrude, both the openings 40 and 42 may be omitted.

  Further, as the stator core 24, any one of a core in which the teeth and the back yoke are integrated, a die split core, a core in which the back yoke and the teeth are split, a skew laminated core, or a sintered core can be used. .

1 is a sectional view of an abduction motor showing one embodiment of the present invention. It is a top view of the housing used for an abduction motor. It is a front view of the housing used for an abduction motor. It is a top view of the housing used for the conventional electric motor. It is a front view of the housing used for the conventional electric motor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 External rotation type motor 12 Boss member 14 Housing 16 Stator 18 Bearing 20 Rotor 22 Motor output shaft 24 Stator core 26 Coil 28 Rotor core 30 Magnet 32 Groove 34 Tap hole 36 Tap screw 38 Grounding terminal 40, 42 Opening 44 Grounding wiring

Claims (3)

  A substantially hollow cylindrical housing, a stator fixed to the outer periphery of the housing, a bearing fixed to the outer periphery of the housing, a rotor rotatably connected to the bearing and disposed outside the stator; The housing is disposed concentrically with the rotor, and a groove having a substantially U-shaped cross section is formed at an axial end of the housing from the axial end surface of the housing along the axial center of the housing. A mounting hole is formed in the axial end surface of the groove along the axial direction. A grounding terminal is fixed to the mounting hole by fastening a fastening member, and a grounding wiring connected to the grounding terminal is provided. A rotating electrical machine drawn out of the housing together with power supply wiring.   2. The rotating electrical machine according to claim 1, wherein at least one opening that is continuous with the axial end surface of the groove is formed adjacent to the axial end surface of the groove.   The rotating electrical machine according to claim 2, wherein a part of the ground terminal is accommodated in the opening.

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