CN108667198B

CN108667198B - Cooling aid and coreless brushless motor

Info

Publication number: CN108667198B
Application number: CN201711239766.5A
Authority: CN
Inventors: 白木学; 大桃修一
Original assignee: M Link Co ltd
Current assignee: M Link Co ltd
Priority date: 2017-03-27
Filing date: 2017-11-30
Publication date: 2021-12-07
Anticipated expiration: 2037-11-30
Also published as: JP6579522B2; CN108667198A; JP2018164373A

Abstract

A coreless brushless motor which is fixed to an outer yoke by a cooling aid or by fitting the cooling aid, the cooling aid being constituted by a circular ring, and fitting a circumference near a bottom of the outer yoke fixed in the coreless brushless motor, the coreless brushless motor comprising: a rotor having a base, an inner yoke and an outer yoke, and a plurality of magnets; a stator fixed with a cylinder coil without an iron core is configured in a way of facing a rotor, a plurality of air inlet holes are formed at the bottom in a way of introducing external air into a space formed by the bottom and an inner yoke, a plurality of air outlet holes communicated with an air gap formed by the inner yoke and an outer yoke and communicated with the space penetrate through the periphery of the outer yoke close to the bottom in a belt shape, and a cooling auxiliary element is provided with a plurality of radial communicating openings aligned with the air outlet holes penetrating through the outer yoke.

Description

Cooling aid and coreless brushless motor

Technical Field

The present invention relates to a cooling aid for a brushless rotating electric machine including a stator having a coreless cylindrical coil, and a brushless rotating electric machine including a stator having a coreless cylindrical coil, to which the cooling aid is attached. More specifically, the present invention relates to a cooling aid for a brushless rotating electric machine including a rotor having a bottom portion, an inner cylindrical void forming body, an outer cylindrical void forming body, and a plurality of magnets, and a stator having a coreless cylindrical coil, to which the cooling aid is attached, the stator being disposed so as to face the rotor and having the coreless cylindrical coil fixed thereto.

Background

The motor and the generator are rotating electric machines having the same structure. A rotating electrical machine is illustrated by an electric motor that converts electrical energy into mechanical energy. The motor is a device that outputs electromagnetic force generated by interaction of a magnetic field and current. Although the classification method is various, the classification method is roughly classified into a DC motor having a brush, in which a magnet is used as a stator (stator) and a coil is used as a rotor (rotor), and a brushless motor, in which the coil is used as a stator (stator) and the magnet is used as a rotor (rotor), and electromagnetic force is output from the rotor to the outside. On the other hand, depending on the method of generating the magnetic field, the coil magnetic field type and the permanent magnet magnetic field type are classified into a coil having an iron core (having a core) and a coil having no iron core (having no core). From the above-described division, a brushless motor including a coreless cylindrical coil of a permanent magnetic field type is an object of the present invention.

Therefore, "a brushless rotating electrical machine including a stator having a coreless cylindrical coil" according to the present invention will be described below as a "coreless brushless motor".

In japanese patent laid-open nos. 2012 and 16218 (patent document 1) and 2012 and 30786 (patent document 2), in-wheel motors using coreless cylindrical coils that can be energized are described. First, patent document 1 does not describe cooling of heat generated when the motor is operated. This is not assumed either. On the other hand, patent document 2 discloses a structure in which a braking means fixed to the inner yoke is further provided in a space formed on the inner peripheral surface of the inner yoke of the rotor, and a vent hole is provided to open an end surface of a wheel fixed to the outer yoke to the stator, thereby allowing the space formed on the inner peripheral surface of the inner yoke to communicate with the outside air. Only the vent hole communicating with the outside air is provided, and it can be considered as a structure for releasing frictional heat generated by the brake unit to the outside. Both of these patent documents are techniques related to an in-wheel motor, which are not related to the coreless brushless motor of the present invention and its cooling method.

Japanese patent No. 2657192 (patent document 3) describes a linear dc brushless motor in which an air supply passage is provided through a fixed armature, and "a structure is provided in which air is directly blown from the air supply passage to the armature coil to cool the armature coil, and a stator yoke itself with respect to the yoke is also cooled". However, the air supply is not caused by the negative pressure generated around the rotor.

An outer rotor type in-wheel motor is described in japanese patent application laid-open No. 2006-246678 (patent document 4). In this motor, that is, in an SR motor including a stator-side 6-pole and rotor-side 4-pole salient-pole core attached to a hollow axle, a method of cooling a coil formed by winding a lead wire attached to the stator-side 6-pole in multiple layers is described. The cooling method is a method in which an inflow passage and an exhaust passage are provided on a hollow axle with a partition wall interposed therebetween, air is circulated over the surface of a coil, and then the air is exhausted to the outside of a stator, and the air merely wipes the exposed surface of a lead wire formed by winding a plurality of layers, and cannot cool stored heat inside the coil formed by winding the lead wire.

An outer rotor type magnet generator described in japanese patent No. 3494056 (patent document 5) is not a brushless motor including a coreless cylindrical coil of the present invention, and includes a stator formed by winding a coil formed by winding a plurality of layers of conductive wires around a ring-shaped stator core, and a rotor formed by an outer yoke supporting a permanent magnet on an inner circumferential surface of a cylindrical portion covering an outer circumference of the stator. In this motor, a ventilation opening is provided in a plate that supports a stator rotatably connected to a rotating shaft, and in order to cool a surface of a coil formed by winding a plurality of layers of conductive wires around a stator core and a permanent magnet, the plate is communicated with a ventilation opening provided in a bottom portion of a rotor, and the rotor is rotated so that air enters from the ventilation opening of the plate, is discharged from the ventilation opening of the rotor, and is further blown toward a cylindrical portion of the rotor to be cooled. However, in the outer rotor type magneto generator, it is not possible to perform thermal cooling inside a coil in which a plurality of layers of wires are wound. This is also not the coreless brushless motor of the present invention.

Japanese unexamined patent publication No. 5-22133 (patent document 6) describes a method of forcibly cooling the inside of an outer rotor type in-wheel motor for an electric vehicle, but the present invention is not a coreless brushless motor that introduces outside air by using negative pressure generated around a rotor.

Japanese patent No. 2831348 (patent document 7) describes an electromagnetic converter that supplies a cooling gas medium into a housing, and the supply of the cooling gas medium into the housing is forcibly supplied by a blower, which is not a coreless brushless motor of the present invention that introduces outside air by using negative pressure generated around a rotor.

Japanese patent No. 3704044 (patent document 8) describes a brushless motor using an energizable coreless cylindrical coil having a laminated structure of conductive metal sheets having a plurality of linear portions separated in a longitudinal direction, each linear portion of the conductive metal sheets being covered with an insulating layer, but no idea is known at all about a method and a cooling means for cooling the cylindrical coil and/or the plurality of exposed magnets arranged in a state of floating in an air gap.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open No. 2012 and 16218

Patent document 2: japanese laid-open patent publication No. 2012 and 30786

Patent document 3: japanese patent No. 2657192

Patent document 4: japanese laid-open patent publication No. 2006-246678

Patent document 5: japanese patent No. 3494056

Patent document 6: japanese Kokai publication Hei-5-22133

Patent document 7: japanese patent No. 2831348

Patent document 8: japanese patent No. 3704044

Disclosure of Invention

Technical problem

In the coreless brushless motor configured as described below, since a temperature rise inside the motor due to copper loss of the cylindrical coil and heat generation by eddy current generated in the conductor is recognized as a technical problem of reducing the efficiency η of such a coreless brushless motor, various proposals have been made so far, but the effects of these proposals are limited and the problem cannot be fundamentally solved. The inventor has developed a coreless brushless motor according to the present invention in order to solve such a problem. The coreless brushless motor is configured such that a rotor having a plurality of magnets attached so as to be exposed in an air gap is arranged so as to face a cylindrical coil having an iron-less core that can be energized and a stator to which one end face of the cylindrical coil is fixed, the air gap is formed by a bottom portion, an inner cylindrical air passage forming body, and an outer cylindrical air passage forming body, and the cylindrical coil is arranged, and a 2 nd air gap located inside the closed cylindrical coil and a 3 rd air gap located outside the cylindrical coil and in contact with an external gas are formed between an open end face of the rotor and the stator.

Technical scheme

The present invention is directed to a cooling aid and a coreless brushless motor in which the cooling aid is fitted and fixed to an outer cylindrical hollow passage forming body, the cooling aid being formed of a ring and fitted and fixed to a circumference of the outer cylindrical hollow passage forming body near a bottom portion of the coreless brushless motor, the coreless brushless motor including: a rotor having a bottom, an inner cylindrical void forming body, an outer cylindrical void forming body, and a plurality of magnets; the stator is provided with a plurality of air intake holes formed in the bottom portion so as to introduce outside air into a space formed by the bottom portion and the inner cylindrical air passage forming body, a plurality of air discharge holes communicating with an air gap formed by the inner cylindrical air passage forming body and the outer cylindrical air passage forming body and communicating with the space are penetratingly provided in a band shape on a circumference of the outer cylindrical air passage forming body near the bottom portion, and the cooling aid has a plurality of radial communication ports provided so as to be aligned with the air discharge holes penetratingly provided on the outer cylindrical air passage forming body.

The present invention has the following features. When the coreless cylindrical coil is energized, the rotor operates. Thereby, the permanent magnet field type coreless brushless motor is started, and a pressure difference is generated around the rotor due to the rotation of the rotor. External air is introduced from an air inlet hole at the bottom of the rotor according to the generated pressure difference into the 2 nd gap or space inside the cylindrical coil formed by the bottom and the inside cylindrical void forming body. Meanwhile, the external air is introduced from the 3 rd gap formed by the open end of the rotor and the stator to the outside of the cylindrical coil of the air gap.

However, if no air inlet hole is provided at the bottom of the rotor, how the outside air acts on the coreless brushless motor. The external gas is instantaneously introduced only from the 3 rd gap by the pressure difference generated around the rotor. However, since there is no outlet for discharging the introduced external air to the outside, it is conceivable that the pressure difference around the rotor disappears instantaneously to be balanced with the external air pressure. Therefore, no flow of outside air is generated inside the motor, and the inside is cooled only by a temperature difference from the outside air.

However, according to the present invention, the external air introduced into the 2 nd gap or the inner space of the cylindrical coil by the pressure difference generated around the rotor flows inside the cylindrical coil disposed in the air gap to cool the inner surface of the cylindrical coil. Further, the outside air introduced from the 3 rd gap to the outside of the cylindrical coil flows outside the cylindrical coil to cool the outer surface of the cylindrical coil. The introduced external air cools both surfaces of the plurality of magnets attached so as to be exposed to the air gap and the cylindrical coil disposed in the air gap, and after flowing through the air vent of the outer cylindrical air passage forming body of the rotor, the external air is discharged to the outside through the communication port of the cooling aid.

When the coreless brushless motor of the present invention is started, the air intake hole in the bottom of the rotor, the air discharge hole of the outer cylindrical cavity forming body, and the communication port of the cooling aid are interlocked to generate a pressure difference around the rotor, thereby introducing the external air from the air intake hole and the 3 rd gap, and the introduced external air flows through the air gap to be cooled, and then passes through the air discharge hole and is discharged to the outside through the communication port.

Of interest from a technical point of view is the role of the 3 rd void. When a coreless brushless motor comprising a rotor having an air intake hole in the bottom of the rotor but no air discharge hole in the outer cylindrical hollow passage forming body is operated, the 3 rd space operates as an air discharge hole. Specifically, the reason is that the outside air introduced from the air intake hole in the bottom of the rotor into the inside space or the 2 nd space of the inside cylindrical void forming body passes through the inside of the cylindrical coil arranged in the air gap by the pressure difference around the rotor, and is discharged from the 3 rd space via the outside of the cylindrical coil. However, if the air discharge hole communicating with the air gap is provided through the circumference of the outer cylindrical passage forming body near the bottom, the pressure difference around the rotor causes the outside air to be introduced from the air intake hole into the inner space or the 2 nd space of the inner cylindrical passage forming body, and also causes the outside air to be introduced into the air gap from the 3 rd space toward the air discharge hole. I.e. the 3 rd gap changes function in a way that works as an air intake.

As shown in fig. 1 and 2, a first aspect of the present invention is a cooling aid 700 comprising an annular ring fitted and fixed to an outer cylindrical void forming body 600 in a coreless brushless electric motor 1 and close to a connection portion connecting the outer cylindrical void forming body 600 and an inner cylindrical void forming body 500, the coreless brushless electric motor 10 comprising: a rotor 3 having a bottom portion 420, an inner cylindrical air passage forming body 500, an outer cylindrical air passage forming body 600 and a plurality of magnets, and a stator 2 to which a coreless cylindrical coil 200 capable of being energized is fixed, which is disposed so as to face the rotor 3, a plurality of intake holes 430 are formed in the bottom portion 420 so as to introduce external air into a space 540 formed by the bottom portion 420 and the inner cylindrical air passage forming body 500, a plurality of exhaust holes 660 communicating with an air gap 40 formed by the inner cylindrical air passage forming body 500 and the outer cylindrical air passage forming body 600 and communicating with the space 540 are provided in a band shape on the circumference of the outer cylindrical air passage forming body 600 near the bottom portion 620, and the cooling aid 700 has a plurality of radial communication ports 720 provided so as to align with the exhaust holes 660 of the outer cylindrical air passage forming body 600.

Preferably, the cooling aid 700 is formed of a ring including a resin ring, is detachably fitted and fixed to the outer cylindrical cavity formation member 600, and is formed with a communication port 720 corresponding to the exhaust hole 660 of the outer cylindrical cavity formation member 600, and the communication port 720 has at least an inner diameter Φ of the exhaust hole 660 and a length L.

As shown in fig. 1 and 2, the 2 nd embodiment of the present invention is a brushless rotating electrical machine 1 including a stator 2 having a coreless cylindrical coil 200, a rotor 3, which constitutes the brushless rotating electrical machine 1 including the stator 2 having the coreless cylindrical coil 200, having a bottom portion 420, an inner cylindrical air passage forming body 500, and an outer cylindrical air passage forming body 600, has a plurality of air intake holes 430 formed in the bottom portion 420 for introducing external air into a space 540 formed by the bottom portion 420 and the inner cylindrical air passage forming body 500, an air gap 40 is formed by the inner cylindrical air passage forming body 500 and the outer cylindrical air passage forming body 600, the inner cylindrical air passage forming body 500 and the outer cylindrical air passage forming body 600 are arranged in a state where the cylindrical coil 200 of the stator 2 supported by a rotating shaft 100 so as to be rotatable so as to face the rotor 3 fixed to the rotating shaft 100 is floated, and a plurality of magnets 4 are attached so as to be exposed to the air gap 40, a plurality of air discharge holes 660 communicating with the air gap 40 are penetratingly provided in a band shape on a circumference of the outer cylindrical passage forming body 600 close to the bottom 620 where the air gap 40 is closed, and the cooling aid 700 constituted by a ring provided with a plurality of radial communication ports 720 corresponding to the air discharge holes 660 is fitted and fixed to the outer cylindrical passage forming body 600 so that the communication ports 720 and the air discharge holes 660 are aligned.

Preferably, the cooling aid 700 includes a resin ring, and is detachably fitted and fixed to the outer cylindrical air passage forming body 600 of the brushless rotating electric machine 1 including the stator 2 including the coreless cylindrical coil 200, and the communication port 720 formed in the cooling aid 700 has at least the inner diameter Φ of the air discharge hole 660 and the length L so as to correspond to the air discharge hole 660 of the outer cylindrical air passage forming body 600.

As is apparent from the first and second aspects of the present invention, the brushless rotating electric machine 1 including the stator 2 including the coreless cylindrical coil 200 introduces the outside air 70 into the space 540 from the air inlet hole 430 by the pressure difference around the rotor 3 generated by the rotation of the rotor 3, the outside air 70 introduced into the space 540 is caused to flow inside the cylindrical coil 200 disposed in the air gap 40 by the pressure difference around the rotor 3, and the flowing outside air 70 cools the plurality of magnets 4 and the cylindrical coil 200 attached so as to be exposed to the air gap 40, and is discharged to the outside through the communication port 720 of the cooling aid 700 via the air discharge hole 660 of the outer cylindrical air passage forming body 600.

As shown in fig. 1 and 2, a brushless rotating electric machine 1 according to embodiment 3 of the present invention includes a stator 2 including a coreless cylindrical coil 200, and includes: a stator 2 having a coreless cylindrical coil 200 capable of being energized and a cover fixture 300 for fixing one end face 201 of the cylindrical coil 200 and rotatably connecting a drive shaft 100 to a center portion 310; a rotor 3 having: a cup fixture 40, the cup fixture 40 being disposed on the opposite side of the cover fixture 300 with the drive shaft 100 coupled and fixed to the center portion 410, and having a bottom portion 420, an inner cylindrical void formation body 500, and an outer cylindrical void formation body 600; and a plurality of magnets 4 disposed on the inner circumferential surface 610 of the outer cylindrical hollow passage forming body 600 and/or the outer circumferential surface 520 of the inner cylindrical hollow passage forming body 500,

the cup type stator 400 is disposed so that the air gap 40 of the 1 st gap is formed by the bottom part 420, the inner cylindrical passage forming member 500, and the outer cylindrical passage forming member 600, and the plurality of magnets 4 are exposed to the air gap 40, the other end surface 202 of the cylindrical coil 200 is disposed in a state where the cylindrical coil 200 floats up with the gap 42 left between the bottom part 420, the 2 nd gap 20 of the space inside the cylindrical coil 200 and the 3 rd gap 30 of the space outside the cylindrical coil 200 communicating with the outside air are provided between the open end surfaces 530 and 630 of the cup type stator 400 and the cover type stator 300,

the cup fixture 400 has the air intake hole 430 communicating with the 2 nd gap 20 in the bottom portion 420, and a plurality of air discharge holes 660 communicating with the air gap 40 are penetratingly provided in a band shape on a circumference of the outer cylindrical passage forming body 600 near the bottom portion 620, and the cooling aid 700 constituted by a circular ring provided with a plurality of radial communication ports 720 corresponding to the air discharge holes 660 is fitted and fixed to the outer cylindrical passage forming body 600 such that the communication ports 720 and the air discharge holes 660 are aligned, and the external air 70 introduced from the air intake hole 430 to the 2 nd gap 20 and the external air 80 introduced from the 3 rd gap 30 to the air gap 40 are circulated in the air gap 40 by a pressure difference around the rotor 3 generated by rotation of the rotor 3, and both faces of the plurality of magnets 4 arranged to be exposed to the air gap 40 and the cylindrical coil 200 arranged in the air gap 40 are cooled and pass through the air discharge holes 660 of the outer cylindrical passage 600, is discharged to the outside through the communication port 720 of the cooling aid 700.

Preferably, the cooling aid 700 is formed of a resin ring, and is detachably fitted and fixed to the outer cylindrical passage forming body 600 of the brushless rotating electric machine 1 including the stator 2 including the coreless cylindrical coil 200, and the communication port 720 formed in the cooling aid 700 has at least the inner diameter Φ of the exhaust hole 660 and the length L so as to correspond to the exhaust hole 660 of the outer cylindrical passage forming body 600.

Preferably, the coreless cylindrical coil 200 that can be energized and that constitutes the brushless rotating electric machine 1 including the stator 2 provided with the coreless cylindrical coil 200 has a cylindrical shape having a laminated structure composed of a plurality of conductive metal sheets, the conductive metal sheets have a plurality of linear portions separated in the longitudinal direction, and each linear portion of the conductive metal sheet is covered with an insulating layer.

As is apparent from the 3 rd aspect of the present invention, a brushless rotating electrical machine 1 including a stator 2 having a coreless cylindrical coil 200 introduces external air 70 from an air inlet hole 430 to a 2 nd gap 20 and introduces external air 80 from a 3 rd gap 30 to an air gap 40 by a pressure difference around a rotor 3 generated by rotation of the rotor 3, the external air 70 introduced to the 2 nd gap 20 is caused to flow inside the cylindrical coil 200 disposed in the air gap 40 by the pressure difference generated around the rotor 3, the external air 80 introduced to the air gap 40 is caused to flow outside the cylindrical coil 200, both faces of a plurality of magnets 4 disposed so as to be exposed to the air gap 40 and the cylindrical coil 200 disposed in a floating state in the air gap 40 are cooled by the flowing external air, and the flowing external air is caused to pass through an air outlet hole 660 of an outer cylindrical passage 600, is discharged to the outside through the communication port 720 of the cooling aid 700.

The term "inner cylindrical void formation body" and "outer cylindrical void formation body" are usually made of magnetic materials, and therefore the inner cylindrical void formation body is used as the inner yoke and the outer cylindrical void formation body is used as the outer yoke. A brushless rotating electric machine including a stator having a coreless cylindrical coil is abbreviated as a coreless brushless motor.

Drawings

Fig. 1 is a schematic view showing a coreless brushless motor according to an embodiment of the present invention.

Fig. 2 is a sectional view of a coreless brushless motor CPH50 to be tested used in a measurement experiment for evaluating a cooling effect.

Fig. 3 is a front view and a plan view of the cooling aid fitted and fixed to the outer yoke of the coreless brushless motor CPH50 shown in fig. 2.

Fig. 4 is a schematic diagram of a measurement experiment for evaluating the cooling effect by the coreless brushless motor CPH50 shown in fig. 2 and 3.

Fig. 5 is a graph showing the results of a measurement experiment for evaluating the cooling effect when CPH50 was driven at 48V.

Fig. 6 is a table of measurement data of the measurement experiment of fig. 5.

Fig. 7 is a graph of the results of other measurement experiments for evaluating the cooling effect in the case of driving CPH50 at 24V.

Fig. 8 is a table of measurement data of other measurement experiments of fig. 7.

Fig. 9 is a graph of the results of other measurement experiments for evaluating other cooling effects in the case of driving CPH50 at 36V.

FIG. 10 is a table of measurement data for another measurement experiment of FIG. 9.

FIG. 11 is a front view and a top view of a (reference) 2 nd cooling aid having a different shape than the cooling aid of FIG. 3.

Fig. 12 is a measurement data table of measurement experiments (at 48V, 24V, and 36V) for evaluating the cooling effect based on the coreless brushless motor CPH50 to be tested using the cooling aid of the 2 nd in fig. 11.

Description of the marks

1: brushless rotating electric machine including stator having coreless cylindrical coil

2: stator

3: rotor

4: magnet

10: brushless rotating electric machine or coreless brushless electric machine including stator having coreless cylindrical coil

20: no. 2 gap

30: no. 3 gap

40: air gap of No. 1 gap

41: inside clearance

42: intermediate space

43: outside clearance

70: external gas introduced into the 2 nd gap

80: external gas introduced from the 3 rd gap

100: drive shaft

200: cylindrical coil

201: end (fixed) face of cylindrical coil

202: the (open) end faces of the cylindrical coil

210: inner peripheral surface of cylindrical coil

220: outer peripheral surface of the cylindrical coil

300: cover type fixing piece

310: center part of cover type fixing member

400: cup-shaped fixing piece

410: center part of cup-shaped fixing member

420: bottom of cup-shaped fixing piece

430: air intake

431: air inlet filter

500: inner cylinder void forming body or inner yoke

530: open end face of inner cylindrical hollow passage forming body or inner yoke

540: inner space of inner cylindrical void forming body or inner yoke

600: outer cylinder clearance forming body or outer yoke

620: bottom of outer cylinder open passage forming body or outer yoke

630: open end face of outer cylindrical passage forming body or outer yoke

660: exhaust hole penetrating through bottom of outer cylinder hollow path forming body or outer yoke

700: cooling aid

720: communication port of cooling auxiliary member

800: generator

810: variable load

900: drive device

910: power meter

920: torque meter

930: torque sensor

Detailed Description

The generated torque T (N · m), which is one of the performances of the motor, is proportional to the intensity i (a) of the current flowing in the armature coil, and the output p (w) is represented by the product of the torque T (N · m) and the rotational angular velocity ω (rad/s). On the other hand, in terms of voltage drop, the product of the power supply voltage v (v) and the current i (a) flowing through the armature coil and the resistance R (Ω) of the armature coil is added to the back electromotive force E, which is the induced electromotive force₀And (V) matching the formula.

T＝Kt×I···(1)

P＝T×ω···(2)

V＝IR+E₀···(3)

As can be seen from the above equation, it is important to decrease the coil resistance value in order to increase the torque and the output.

Therefore, if the basic structure of the coreless brushless motor 1 of the present invention shown in fig. 1, which characterizes the present invention, is summarized, the first basic structure is characterized in that a cylindrical coil formed by a laminated structure of conductive metal sheets is used as a coil main body constituting the stator 2, which is capable of being energized. As described in patent document 8, for example, the cylindrical coil and the manufacturing method thereof have a cylindrical shape having a laminated structure of a plurality of conductive metal sheets having a plurality of linear portions separated in a longitudinal direction, each linear portion of the conductive metal sheet being covered with an insulating layer, and preferably having a certain rigidity of 5mm or less in thickness, which is formed of 2 layers or 4 layers.

As a feature of the second basic structure, it has the following structure: one end face of the cylindrical coil is closed by an inner peripheral face of a cover-type stator constituting the stator 2, and the other open end face of the cylindrical coil is inserted and arranged in a state of being floated in an air gap of a 1 st gap in which a magnetic field having an annular cross section is formed, by passing through a bottom portion of a cup-type stator constituting the rotor 3 and an outer yoke and an inner yoke made of a magnetic material to which a plurality of magnets (permanent magnets) 4 are attached.

More specifically, the cylindrical coil inserted and disposed in the air gap is floated in the air gap with a very small gap so that the inner circumferential surface and the outer circumferential surface thereof do not contact the inner circumferential surface of the outer yoke and the outer circumferential surface of the inner yoke of the rotor 3, and the other end surface thereof does not contact the bottom of the cup fixture constituting the rotor 3. In order to arrange the cylindrical coil in this manner, the stator 2 and the rotor 3 are arranged on the drive shaft.

As a feature of the third basic structure, it has the following structure: the stator 2, the cylindrical coil, and the rotor 3 form a 2 nd gap 20 of an inner space of the cylindrical coil and a 3 rd gap 30 of an outer space of the cylindrical coil which is in contact with an external gas. More specifically, the 2 nd gap 20 is formed between the open end surfaces of the outer yoke and the inner yoke integrated with the rotor 3, which are open, and the inner surface of the stator 2 facing the open end surfaces, on the inner peripheral surface of the cylindrical coil closed by the inner surface of the stator 2. Of course, the gap communicates with the air gap.

When the coreless brushless motor 1 of the present invention having a plurality of air intake holes formed in the bottom of the cup fixture constituting the rotor 3 is operated, the outside air is introduced from the air intake holes to the 2 nd gap by the pressure difference around the rotor 3 generated by the rotation of the rotor 3. Further, a 3 rd gap is formed between the air gap and the outside air at the outer peripheral surface of the cylindrical coil closed by the inner surface of the stator 2. Then, the 2 nd gap which becomes a closed space formed by the inner peripheral surface of the cylindrical coil and the inner surface of the stator 2 can communicate with the air gap, and communicate with only the 3 rd gap which becomes an open space formed by the outer peripheral surface of the cylindrical coil, the inner surface of the stator 2, and the open end surface of the outer yoke via the inner surface of the rotor 3.

When the coreless brushless motor 1 of the present invention is operated without the air vent hole communicating with the air gap in the outer yoke, the external air introduced from the air inlet hole to the 2 nd gap by the pressure difference around the rotor 3 passes through the inner peripheral surface of the cylindrical coil and is discharged from the 3 rd gap to the outside through the outer peripheral surface. That is, since the air intake hole provided at the bottom of the rotor 3 is an inlet of the outside air, the 3 rd gap becomes an outlet for the exhaust air.

However, in the coreless brushless motor 1 of the present invention, the air discharge hole communicating with the air gap is provided through the outer yoke, and the cooling aid having the communication port corresponding to the air discharge hole is fitted and fixed so that the communication port and the air discharge hole are aligned. Then, the outside air is introduced from the air intake hole to the 2 nd gap by the pressure difference around the rotor 3, and on the other hand, the 3 rd gap 30 functions to change from the air exhaust hole to the air intake hole, thereby additionally introducing the outside air from the 3 rd gap 30. These external air passes through the air gap and is discharged to the outside from the communication port via a plurality of exhaust holes provided through the outer yoke.

More specifically, the coreless brushless motor 1 of the present invention has a completely new feature that the higher the rotation speed of the rotor 3, that is, the larger the output P, the larger the pressure difference around the rotor 3 becomes, the larger the amount of the introduced external air increases, and the cooling effect improves. This results from the basic structure of the coreless brushless motor 1 of the present invention described above. That is, the coreless brushless motor according to the present invention is characterized by a structure that operates as follows: the coreless cylindrical coil, which has no increased iron loss when the rotation speed is increased, is inserted and arranged in a state of floating in a narrow air gap having a large magnetic flux density, and on the one hand, the inner peripheral surface of the cylindrical coil arranged in the air gap is cooled by the outside air introduced into the 2 nd air gap 20 of the closed space, and on the other hand, the outer peripheral surface of the cylindrical coil is cooled by the outside air introduced into the air gap from the 3 rd air gap by the negative pressure state formed at this time, and the outside air is discharged from the communication port to the outside through the plurality of exhaust holes of the outer yoke.

[ measurement experiment for evaluating Cooling Effect by communication opening ]

In order to evaluate the cooling effect when the usage area of the coreless brushless motor CPH50 under test of the present invention was set to 48V, the cooling effect of the outside air introduced from the plurality of air intake holes 430 and the 3 rd air gap 30 provided in the bottom part 420 constituting the rotor 3 by the pressure difference generated around the rotor 3 by operating the coreless brushless motor under test CPH50 was evaluated based on the following 3 types of forms.

[1] Comparative example a: the CPH50 not using the cooling aid 700 and not provided with the vent hole 660 is operated, that is, the 3 rd gap 30 functions as a vent hole.

[2] Comparative example B: the CPH50 not using the cooling aid 700 is operated in such a manner that the external air introduced from the air intake holes 430 and the external air introduced from the 3 rd gap 30 are discharged to the outside from the air discharge holes 660 of the outer yoke 600, which is a form in which the 3 rd gap 30 functions as an air intake hole.

[3] Measurement example C of the present invention: in the case where the CPH50 is operated so that the outside air introduced from the intake hole 430 and the outside air introduced from the 3 rd gap 30 are discharged to the outside from the communication port 720 of the cooling aid 700 fitted and fixed to the outer yoke 600 through the exhaust hole 660 of the outer yoke 600, the 3 rd gap 30 functions as an intake hole, and the introduced outside air is discharged to the outside from the communication port 720 through the exhaust hole 660.

Fig. 2 shows a sectional view (a) and a front view (b) of a coreless brushless motor CPH50 to be tested. Although not shown, a sensor for measuring the temperature of the cylindrical coil is attached near the portion of the cylindrical coil exposed in the 3 rd gap.

To summarize the coreless brushless motor CPH50 to be tested, first, a cylindrical coil having a thickness of 1.85mm and an outer diameter of 32.2mm is inserted into the air gap 40 disposed in the 1 st air gap having a width of 6.25mm and a length of 42.55mm in the longitudinal direction. As shown in the sectional view (b), in the magnet 4, 6 neodymium magnets each having a rectangular parallelepiped shape with a thickness of 3.5mm were arranged on the inner peripheral surface of the outer yoke at intervals of 2.57mm in the circumferential direction.

Between the open end surfaces 530 and 630 of the outer yoke 600 and the inner yoke 500 integrated with the rotor 3 and the inner surface of the stator 2 facing the open end surfaces, a 2 nd gap 20 having a width of 2.5mm and a 3 rd gap 30 having a width of 1.5mm are formed. In addition, 24 air discharge holes 660 having a diameter of 3mm are formed through the band-shaped circumference of the outer yoke 600 near the connection portion connecting the outer yoke 600 and the inner yoke 500. When the form of CPH50 which does not have the vent holes 660 is supposed to be measured, the form is dealt with by bonding a resin tape to these vent holes 66 from the outer peripheral surface side of the outer yoke. Further, a gap between the inner peripheral surface of the cylindrical coil 200 and the outer peripheral surface of the inner yoke 500 was 0.5mm, and a gap between the outer peripheral surface of the cylindrical coil 200 and the inner peripheral surface of the neodymium magnet was 0.4 mm.

As shown in fig. 3, the cooling aid 700 fitted and fixed to the outer yoke 600 and including the resin ring has an inner diameter Φ of 46.4mm and an outer diameter Φ of 62mm, and 24 communication ports 720 corresponding to the exhaust holes 660 of the outer yoke 600 have a diameter of 3.5mm and a length of the radially extending communication ports of 7.8 mm. In addition, the 24 discharge holes 660 of the outer yoke 600 have a diameter of 3mm and a length of 3.15 mm. Therefore, when the length of the communication port 720 is added to the length of the exhaust hole 660, the length of the passage through which the outside air is exhausted is 10.95 mm. Thereby, the discharge pressure due to the centrifugal force becomes larger, and the cooling effect becomes higher.

FIG. 4 is a schematic diagram of an experimental setup. In this measurement experiment, a power meter (HIOKI 3336)910 is added between the motor drive apparatus 900 and the coreless brushless motor CPH50 to be measured, and measurement is performed, because the generator (m-link CP8048)800 is connected to the output shaft of the coreless brushless motor CPH50 to be measured via a torque sensor (UNIPULSE UTM II-5Nm)930 to which a torque meter (UNIPULSE TM301)920 is connected, the power generated by the generator 800 is consumed by an external variable resistor or the like such as a variable load (three-phase PWM driving power source: ICAN TEC BLD750)810 to generate a load torque and a rotation speed, and the output power derived from the load torque and the rotation speed and the input power to the coreless brushless motor CPH50 to be measured are related to the voltage, the current, and the power factor of the driving state supplied from the driving power source.

The communication port 720 is positioned to face the 24 air discharge holes 660 of the outer yoke 600 of the coreless brushless motor CPH50 to be tested, and the cooling aid 700 is fitted and fixed to the outer yoke 600 so as to be prevented from being biased. The measurement items were such that the upper limit (saturation temperature) of the temperature rise of the cylindrical coil 200 of CPH50 was set to 4 points of load torque, rotational speed, current, and input power of 117 ℃. FIG. 5 is a graph based on measured values showing the relationship between the respective load torques (T/Nm) and the rotational speeds (N/rpm) of CPH50 in comparative example 1, comparative example 2, comparative example B and measurement example C of the present invention in [3] under these conditions. Fig. 6 is a data table of these measured values.

The measurement sequence was as follows. The input power to the driving device 900 is initially set to 48V. The rotational speed of CPH50 is then arbitrarily set. Further, the load torque T/Nm is gradually increased in order while the load torque T/Nm is adjusted by the torque meter 920 by the variable resistance of the variable load 810 of the generator 800. Subsequently, the temperature of the cylinder coil 200 of the CPH50 was measured, and when the saturation temperature 117 ℃ was not reached, the load torque T/Nm was adjusted again. Finally, the load torque T/Nm at which the temperature of the cylinder coil 200 reached the saturation temperature of 117 ℃ was measured.

[ evaluation of measurement experiment ]

Line a in fig. 5 shows a case where 24 vent holes 660 provided in the outer yoke 600 are closed with a resin tape, that is, a measured value when the temperature of the cylindrical coil 200 constituting the CPH50 to be measured in [1] comparative example a is the saturation temperature 117 ℃. The left area of line a of fig. 5 is the normal operating area of the CPH50 under test. Therefore, in the right region of line a indicated by the solid line in fig. 5, the CPH50 to be measured cannot expect a normal operation in terms of performance due to heat generation of the cylindrical coil and/or heating of the magnet of the CPH 50.

One of the technical means for preventing such performance degradation is to add a cooling function by penetrating the air discharge hole 660 provided in the outer yoke 600 in communication with the air gap 40. This is the case of comparative example B [2], which is indicated by line B in FIG. 5. Specifically, the measured value was obtained when the temperature of the cylindrical coil 200 constituting the CPH50 to be measured in comparative example B was 117 ℃. The line B of fig. 5 shows that the load torque is increased in the entire rotation region compared to the line a of fig. 5, and the exhaust hole 660 expands the normal operation region of the CPH50 to confirm that the cooling effect is higher than that of the CPH50 without the exhaust hole 660.

Line C in fig. 5 is a measurement value when the temperature of cylindrical coil 200 constituting CPH50 to be measured in measurement example C of the present invention [3] in which cooling aid 700 having radial communication ports 720 corresponding to the 24 air discharge holes 660 provided in outer yoke 600 is fitted and fixed to outer yoke 600 is at saturation temperature 117 ℃. The cooling aid 700 shown in fig. 3 is fitted and fixed so that the communication ports 720 and the 24 air vent holes 660 are aligned, which is structurally different from the CPH50 to be tested of comparative example 2B. In this way, the length of the passage through which the outside air is discharged was 3.15mm, which is the length of the exhaust hole 660 corresponding to the thickness of the outer yoke, but was now 10.95mm, which is the length of the communication port 720 added by 7.8 mm. The flow rate of the discharged outside air was increased by increasing the centrifugal force in accordance with the extended length of the passage, and the amount of the outside air introduced from the air intake holes 430 and the 3 rd gap was increased, and as a result, it was confirmed that the cooling effect of the measured CPH50 of the measurement example C of the present invention [3] was further improved.

Fig. 7 and 8 are a graph and a measured value data table in the case where the input power to the driving device 900 is set to 24V. Fig. 9 and 10 are a graph and a measured value data table in the case where the input power to the drive device 900 is set to 36V. From the measurement values of [3] in the measurement example C of the present invention, in which the temperature of the cylindrical coil 200 constituting the CPH50 to be measured was 117 ℃, it was confirmed that the load torque was increased in the entire rotational region and the normal operation region of the CPH50 was expanded, as compared with the comparative examples [1] a and [2] B. From this, it was confirmed that the cooling effect was improved as the normal operation region of the CPH50 under test set to 24V, 36V, and 48V was enlarged as the rotation speed was higher.

For reference, FIG. 11 illustrates another shape of the cooling aid 700'. The difference from the cooling aid 700 of fig. 3 is in the length of the communication port 720. The communication port 720 'of the cooling aid 700' having another shape has a length of 3.8mm, which is equal to or less than 1/2 where the length of the communication port 720 is 7.8 mm. The centrifugal force decreases by the length-shortened portion of the passage through which the outside air is discharged, and the flow velocity of the discharged outside air also decreases. Therefore, the amount of the outside air introduced from the intake holes 430 and the 3 rd gap 30 also decreases, and as a result, as shown by the line D in fig. 5, 7, and 9, the measured value at the saturation temperature of 117 ℃ is shown on the left side of the line C.

In addition, the form of the measured CPH50 that closes the inlet vent 430 is not included in the present measurement experiment. In this case, it is self-evident that the introduced external air is insufficient, and therefore the cooling effect becomes low, and the measured value at the saturation temperature of 117 ℃ is located on the left side of the line a of fig. 5.

While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.

Claims

1. A cooling aid characterized by being a cooling aid for a rotating electrical machine,

the rotating electric machine includes:

a rotor having a bottom, an inner cylindrical void forming body, an outer cylindrical void forming body, and a magnet;

a stator that is disposed so as to face the rotor and to which a coreless cylindrical coil that can be energized is fixed;

a plurality of air intake holes formed in the bottom part, introducing external air into a space formed by the bottom part and the inner cylindrical void formation body; and

a plurality of exhaust holes which are arranged on the circumference of the outer cylinder empty passage forming body near the bottom in a strip-shaped penetrating way and communicated with an air gap, wherein the air gap is communicated with the space and is positioned between the inner cylinder empty passage forming body and the outer cylinder empty passage forming body,

the cooling aid is composed of a resin ring having a plurality of radial communication ports aligned with the exhaust holes and detachably fitted and fixed to the outer cylindrical hollow passage forming body,

the cooling aid is fitted and fixed to the outer cylindrical hollow passage forming body so that the communication port and the exhaust hole are aligned with each other.

2. A cooling assistance member according to claim 1, wherein an inner diameter of the communication port is equal to or larger than an inner diameter of the exhaust hole, and a length of the communication port is equal to or larger than a length of the exhaust hole.