JP2014107963A - Motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently dissipate heat within a space surrounded by a stator and a flywheel of a motor, in simple structure.SOLUTION: A motor comprises: a rotor 10 including a rotary shaft 12 and a magnet part 14; a stator 20 including a stator core 22 and a stator coil 24; and a flywheel 50 fixed to the rotary shaft. The stator 20 includes a protruding portion 27 which protrudes closer to the flywheel 50, and an inside space 80 is formed inside of the protruding portion 27. The flywheel 50 includes a plurality of through holes 58 provided at a plurality of positions which are disposed side by side in a rotating direction, respectively. Each of the through holes 58 penetrates the flywheel 50 in an axial direction so as to open the inside space 80 to an outside space 82 of the flywheel 50, and has such a shape as to form an air stream which passes through the through hole 58 with rotation of the flywheel 50.

Description

  The present invention relates to an electric motor used for, for example, a turning drive in a construction machine.

  Conventionally, as an electric motor used in a construction machine or the like, a rotor shaft, a rotor assembled to the rotor shaft, a stator that is arranged around the rotor and includes a coil for forming a magnetic field that rotates the rotor, What is provided with the stator frame which accommodates this stator is known. Further, in this type of electric motor, a disk-like flywheel may be fixed to the rotor shaft for speed control of the rotor shaft.

JP 2009-220771 A

  The flywheel needs to be accommodated in a limited space in the stator frame while being formed in a shape having a large outer diameter in order to secure a large moment of inertia. It is often arranged close to the axial direction. Such an arrangement causes a technical problem that heat tends to be accumulated in the vicinity of the stator.

  Specifically, the stator has a stator core disposed around the rotor shaft and a stator coil wound around the stator core in the axial direction, and a coil end that is an axial end portion of the stator coil is the stator core. Therefore, an inner space is formed inside the coil end in the radial direction. Further, when the flywheel is fixed to the rotor shaft at a position close to the coil end, the inner space is closed from the axial direction by the flywheel.

  Therefore, when a large current flows through the stator coil and the stator coil generates heat, the heat is generated in the inner space, that is, in the space surrounded by the coil end and the flywheel from both the radial direction and the axial direction. It becomes easy to hang up. In addition to the flywheel, it is practically difficult to attach an airflow forming fan in a limited space in the stator shaft in order to dissipate the heat.

  In view of such circumstances, the present invention is an electric motor including a stator and a flywheel, which can efficiently dissipate heat in a space surrounded by the stator and the flywheel with a simple structure. The purpose is to provide.

  An electric motor provided by the present invention includes a rotor having a rotating shaft and a magnet portion fixed on an outer peripheral surface thereof, a stator disposed around the magnet portion of the rotor, and rotating the rotor by electromagnetic force, and the stator A flywheel fixed to the rotary shaft so as to rotate integrally with the rotary shaft at a position adjacent to a direction parallel to the axial direction of the rotary shaft with respect to the axial direction of the magnet portion. The flywheel has a shape that has a protruding portion that protrudes closer to the flywheel side than an end surface that faces the flywheel, and forms an inner space inside the protruding portion. Are provided at a plurality of positions aligned in the rotational direction, and the flywheel is opened to open the inner space to the outer space outside in the axial direction across the flywheel. Having a plurality of through-holes through Le in the axial direction, and these through-holes, those having a shape that forms an airflow through said through-hole with the rotation of the flywheel.

  In this electric motor, since the inner space formed on the radially inner side of the protruding portion of the stator is further covered by the flywheel adjacent in the axial direction, the degree of opening of the inner space is reduced, but the flywheel rotates. By doing so, an airflow passing through a through hole provided in the flywheel is formed, whereby ventilation of the inner space is promoted, and thereby heat accumulation in the inner space is reduced. That is, in this electric motor, it is possible to reduce heat accumulation in the inner space with a rational and simple structure that uses the rotation of the flywheel itself arranged so as to cover the inner space.

  Specifically, it is preferable that the through hole has a shape inclined at least in the rotational circumferential direction of the flywheel with respect to the thickness direction of the flywheel. This tilt allows the air on one side of the flywheel to be forced through the through hole to the other side as the flywheel rotates, i.e., creating an airflow through the through hole. To.

  In the present invention, the direction of the airflow passing through the through hole is not limited, but more preferably, the through hole forms an airflow in a direction from the inner space toward the outer space as the flywheel rotates. It is good to have By forming such an air flow, it becomes possible to directly and effectively dissipate heat in the inner space to the outer space.

  In that case, the through-hole is inclined in the rotational circumferential direction of the flywheel with respect to the thickness direction of the flywheel, and in a direction opposite to the direction of rotation of the flywheel as the distance from the inner space increases. What is necessary is just to have the shape which inclines so that it may displace.

  Further, it is preferable that the flywheel has an outer diameter larger than an outer diameter of the stator, and each of the through holes is disposed in a region inside in a radial direction with respect to the inner diameter of the stator. The flywheel having such a structure can effectively promote the ventilation of the inner space through the plurality of through holes, and the radial distance of each through hole from the center of the flywheel is small. By being suppressed, a large moment of inertia can be maintained regardless of the presence of the through hole, and a high level can be secured for both the original speed control function and the airflow forming function.

  As described above, according to the present invention, an electric motor including a stator and a flywheel, which can efficiently dissipate heat in a space surrounded by the stator and the flywheel with a simple structure. Provided.

It is a section front view of the electric motor concerning an embodiment of the invention. It is a cross-sectional perspective view of the flywheel contained in the said electric motor, Comprising: It is a figure which shows the cross section along the diameter of the said flywheel. It is a cross-sectional perspective view of the flywheel, and shows a cross section along a tangential direction of a circle in which through holes of the flywheel are arranged. It is sectional drawing which shows the inclination-angle to the rotation circumferential direction of the said through-hole in the cross section shown in FIG. It is a graph which shows the relationship between the inclination-angle of the said through-hole, the mass flow rate of the air which flows through this through-hole, and an axial speed.

  Embodiments of the present invention will be described with reference to the drawings. Note that the electric motor according to this embodiment is a generator motor that is interposed between the engine 60 and the pump 70 of the construction machine and performs power generation and driving assistance. However, the electric motor according to the present invention is a target to be driven. And any use. For example, the present invention can also be applied to a turning electric motor for turning an upper turning body relative to a lower traveling body of a turning work machine, or an electric motor dedicated to a pump provided exclusively for driving a hydraulic pump. It is.

  The electric motor according to the embodiment shown in FIG. 1 includes a rotor 10, a stator 20, a stator frame 30, an end cover 40, and a flywheel 50.

  The rotor 10 is supported so as to be rotatable around a specific rotation center axis (a left-right axis in FIG. 1). The rotor 10 extends along the rotation center axis, and this rotation. And a magnet portion 14 provided around an intermediate portion of the shaft 12. The rotating shaft 12 and the magnet portion 14 are coupled together so as to rotate integrally.

  Both ends of the rotating shaft 12 are rotatably supported by the engine 60 and the pump 70. Specifically, one end of the rotary shaft 12 is connected to the engine shaft 62 of the engine 60 via the coupling 16, and the other end is connected to a pump frame 72 of the pump 70 with a bearing (not shown). And is connected to a pump shaft (not shown) in the pump frame 72 via a coupling. The rotating shaft 12 may be rotatably supported by the stator frame 30 or the end cover 40.

  The magnet part 14 includes a cylindrical iron core 15 and a plurality of unillustrated permanent magnets embedded in the iron core 15. The iron core 15 is formed by, for example, laminating a plurality of steel plates along the axial direction of the rotor 10, and the permanent magnets are embedded in the iron core 15 so as to be aligned in the circumferential direction of the rotor. That is, the rotor 10 according to this embodiment constitutes a so-called permanent magnet type synchronous motor, but the rotor according to the present invention is not limited to this. For example, a permanent magnet is disposed on the outer peripheral surface of an iron core (that is, a rotor that constitutes a surface magnet type synchronous motor) or a so-called cage rotor (that is, a rotor that is a dielectric motor). Thing).

  The stator 20 includes a cylindrical stator core 22 disposed around the rotor 10 (in this embodiment, around the magnet portion 14), and a stator coil 24 supported by the stator core 22. The stator core 22 is formed, for example, by laminating a plurality of steel plates in the axial direction of the rotor 10. The stator coil 24 is constituted by a winding wound around the stator core 22, and forms a magnetic field that applies a rotational force to the magnet portion 14 of the rotor 10 by energization of the stator coil 24. The stator coil 24 includes a first projecting end portion 27 projecting from the stator core 22 toward the engine side end portion 12a along the axial direction of the rotor 10 (left side in FIG. 1), and the stator core 22. And a second projecting end portion 28 projecting on the opposite side (right side in FIG. 1) from the first end portion 27 along the axial direction of the rotor 10.

  The stator frame 30 opens in a direction (leftward in FIG. 1) parallel to the axial direction of the rotor 10 on the side opposite to the engine side end 12a of the rotor 10 (upper side in FIG. 1) and is inserted through the opening. The stator 20 is accommodated and the stator core 22 is held. Specifically, the stator frame 30 integrally includes a peripheral wall 32 and an end wall 34, and the stator core 22 is press-fitted inside the peripheral wall 32 or by a fastener such as a bolt. 22 is fixed in the stator frame 30. The end wall 34 is located on the side opposite to the opening of the stator frame 30 (right side in FIG. 1), and a through hole 36 that allows the rotation shaft 12 to pass therethrough is provided at the center thereof.

  The end cover 40 has a through hole 42 that allows the engine shaft 62 to pass therethrough at the center thereof, and an end of the stator frame 30 on the opening side (in FIG. 1) so as to close the opening of the stator frame 30. And is fixed to the outer wall of the casing 64 of the engine 60. That is, in this embodiment, the end cover 40 forms a casing of the electric motor together with the stator frame 30, and the entire casing is supported by the casing 64 of the engine 60.

  The flywheel 50 is fixed to the rotary shaft 12 for speed control. In this embodiment, the flywheel 50 is disposed at a position adjacent to the engine side with respect to the magnet portion 14 of the rotor 10, and the rotation The shaft 12 has a shape that is fixed around both the shafts 12 and 62 so as to straddle the engine-side end portion 12 a of the shaft 12 and the end portion of the engine shaft 62. Specifically, the flywheel 50 according to this embodiment has a substantially disk shape having an outer diameter larger than the outer diameter of the stator 20, and has a through hole 52 that accommodates the coupling 16 in the center. An engine-side boss portion 54 surrounding the end portion of the engine shaft 62 is provided on one side, that is, the engine side with the through hole 52 interposed therebetween, and the engine-side end portion 12a of the rotary shaft 12 is provided on the opposite side, that is, the rotor 10 side. It has a surrounding rotor-side boss portion 56. Therefore, between the outer peripheral surface of the rotor-side boss portion 56 and the inner surface of the first projecting end portion 27 of each stator coil 24 of the stator 20, the first projecting end portion 27 is located on the radially inner side. An inner space 80 is formed, and the flywheel 60 is disposed so as to cover the flywheel 50 from the outside in the axial direction (from the engine side in this embodiment).

  Further, as a feature of the electric motor, the flywheel 50 has a plurality of through holes 58 that penetrate the flywheel 50 in the thickness direction, that is, in a direction parallel to the axial direction of the rotary shaft 12. These through holes 58 are respectively provided at a plurality of positions aligned in the rotational direction of the flywheel 50, and the inner space is provided in the outer space 82 that is a space opposite to the inner space 80 with the flywheel 50 interposed therebetween. Open 80. Specifically, each through hole 58 according to this embodiment is provided at a position radially inward of the inner peripheral surface of the stator 20 and facing the device space 80.

  Further, each through-hole 58 has a shape that forms an air flow from the inner space 80 toward the outer space 82 as the flywheel 50 rotates. Specifically, as shown in FIGS. 2 and 3, the through hole 58 according to this embodiment has a rectangular shape when viewed from the front, and a pair of inner holes facing each other in the rotational radial direction of the flywheel 50. A side surface 58a and a pair of inner side surfaces 58b facing each other in the rotational circumferential direction of the flywheel 50 are surrounded by the inner side surfaces 58b facing each other in the rotational circumferential direction, as shown in FIG. Is inclined at an angle θ. The direction of this inclination is opposite to the direction of rotation of the flywheel 50 as it moves away from the inner space 80 (i.e., toward the outer space 82) to form an air flow from the inner space 80 to the outer space 82. The both inner side surfaces 58b are set to be displaced in the direction, and the inclination angle θ is preferably set within a range of 45 ° to 80 °, and more preferably within a range of 55 ° to 70 °, for reasons described later.

  Next, the operation of this electric motor will be described.

  In the state shown in FIG. 1, when the stator coil 24 of the stator 20 is energized, a magnetic field for rotating the magnet portion 14 of the rotor 10 is formed, thereby having the magnet portion 14 and the rotating shaft 12 fixed thereto. The entire rotor 10 is rotationally driven around the central axis of the rotary shaft 12. Further, the flywheel 50 fixed to the rotary shaft 12 also rotates together with the rotary shaft 12, and the large moment of inertia of the flywheel 50 stabilizes the rotation of the rotor 10.

  On the other hand, the stator coil 24 generates heat when energized, and raises the temperature of the air in the vicinity thereof. Particularly, the inner space 80 formed inside the first projecting end portion 27 of the stator coil 24 is sandwiched from the magnet portion 14 of the rotor 10 and the flywheel 50 from the axial direction, that is, the stator coil. The heat generated by 24 is in a state where it is easy to accumulate. However, in this electric motor, as the flywheel 50 rotates, an air flow from the inner space 80 toward the outer space 82 is formed through the through holes 58, so that the heat in the inner space 80 is positively applied to the outer space. 82, thereby reducing the accumulation of heat in the inner space 80. That is, in this electric motor, it is possible to reduce the accumulation of heat in the inner space 82 with a rational and simple structure using the rotation of the flywheel 50 itself arranged so as to cover the inner space 80. is there.

  The direction of the inclination of each through hole 58 may be the opposite direction to the above, that is, the direction in which the through hole 58 is displaced in the same direction as the rotation direction of the flywheel 50 as the distance from the inner space 80 increases. In this case, an air flow from the outer space 82 to the inner space 80 is formed with the rotation of the flywheel 50, and the formation of such an air flow can also promote ventilation in the inner space 80. It is. Specifically, air is pushed into the inner space 80 from the outer space 82 through the through holes 58, so that the air in the inner space 80 is brought into contact with the flywheel 50 and the first projecting end portion 27 of the stator coil 24. Is pushed out radially through the gap, thereby forming a circulating flow that promotes the ventilation. However, the formation of the airflow from the inner space 80 toward the outer space 82 as described above makes it possible to dissipate the heat in the inner space 80 to the outer space 82 more directly and effectively.

  Further, each through hole 58 may be inclined in the rotational radial direction in addition to the rotational circumferential direction of the flywheel 50. For example, in the case where each through hole 58 of the flywheel 50 according to the embodiment has a rotational radial inclination that is displaced radially outward as the distance from the inner space 80 increases in addition to the rotational circumferential inclination. The air in the inner space 80 can be sent out so as to actively diffuse radially outward with respect to the outer space 82.

  In the present invention, the specific number, position, and shape of each through hole 58 are not limited. For example, the cross-sectional shape of each through hole 58 may be a shape other than a rectangle, such as a circle or other closed curve. Also in this case, if the central axis of the through hole 58 is inclined at least in the circumferential direction of the rotation, an airflow passing through the through hole 58 can be formed. Further, the through holes 58 do not necessarily have to be arranged on the same circle. For example, through holes having different distances from the center of the flywheel 50 may be mixed.

  The outer diameter and specific cross-sectional shape of the flywheel 50 are not limited. For example, as shown in FIG. 1, it may not be provided across the rotating shaft 12 of the rotor 10 and the engine shaft 62 but may be fixed only to the rotating shaft 12 or smaller than the outer diameter of the stator 20. It may have an outer diameter. However, the flywheel 50 has an outer diameter larger than the outer diameter of the stator 20, and each through hole 58 is disposed in a region radially inward of the inner diameter of the stator 20. In addition to effectively promoting ventilation of the inner space 80 through the plurality of through holes 58, the radial distance of each through hole 58 from the center of the flywheel 50 while increasing the outer diameter thereof It is possible to hold a large moment of inertia regardless of the presence of the through hole 58 by keeping the value of the angle small. That is, the flywheel 50 satisfying such a condition can secure a high level for both the original speed control function and the airflow forming function.

  As described above, the formation of the airflow effective for cooling the electric motor is achieved by the inclination of the through holes 58 in the rotational circumferential direction. FIG. 5 shows the result of the calculation of the relationship between the inclination angle θ of the through hole 58 in the rotational circumferential direction, the mass flow rate of the air flowing through each through hole 58 and the axial velocity by simulation. The solid line in the figure indicates the mass flow rate, and the alternate long and short dash line indicates the axial velocity. The preconditions for the simulation are as follows.

Number of through holes 58: 30 Dimensions of each through hole 58 in the rotational circumferential direction: 20 mm
Dimensions in the radial direction of each through hole 58: 14 mm
Thickness of the flywheel 50 where each through hole 58 is formed: 12 mm
Distance from the center of the flywheel 50 to the center of each through hole 58: 120 mm
Number of revolutions of flywheel 50: 2000 rpm
As shown in FIG. 5, it is possible to obtain a large mass flow rate and an axial velocity in the range where the inclination angle θ of the through hole 58 is 45 ° or more and 80 ° or less, and this effect is particularly effective at 55 ° to 70 °. It becomes remarkable in the range.

DESCRIPTION OF SYMBOLS 10 Rotor 12 Rotating shaft 14 Magnet part 20 Stator 22 Stator core 24 Stator coil 27 1st protrusion end part 50 Flywheel 58 Through hole 58a Inner side surface 58b Inner side surface 60 Engine 62 Engine shaft 64 Casing 70 Pump 72 Pump frame 80 Inner space 82 Outer side space

Claims (5)

An electric motor,
A rotor having a rotating shaft and a magnet portion fixed on the outer peripheral surface thereof;
A stator disposed around the magnet portion of the rotor and rotating the rotor by electromagnetic force;
A flywheel fixed to the rotation shaft so as to rotate integrally with the rotation shaft at a position adjacent to the stator in a direction parallel to the axial direction of the rotation shaft;
The stator has a protruding portion that protrudes closer to the flywheel side than the end surface facing the flywheel among the axial end surfaces of the magnet portion, and an inner space is formed inside the protruding portion. Has a shape to form,
The flywheel is provided at a plurality of positions aligned in the rotation direction, and penetrates the flywheel in the axial direction so as to open the inner space to an outer space outside in the axial direction across the flywheel. An electric motor having a plurality of through holes and having a shape that forms an airflow passing through the through holes as the flywheel rotates.   2. The electric motor according to claim 1, wherein the through hole has a shape inclined at least in a rotational circumferential direction of the flywheel with respect to a thickness direction of the flywheel. 3.   The electric motor according to claim 1, wherein the through hole has a shape that forms an airflow in a direction from the inner space toward the outer space as the flywheel rotates.   4. The electric motor according to claim 3, wherein the through hole is inclined in a rotational circumferential direction of the flywheel with respect to a thickness direction of the flywheel, and the direction of rotation of the flywheel as the distance from the inner space increases. An electric motor having a shape that is inclined so as to be displaced in the opposite direction.   5. The electric motor according to claim 1, wherein the flywheel has an outer diameter larger than an outer diameter of the stator, and each of the through holes is radially inward of the inner diameter of the stator. An electric motor arranged in the area.

Images