AU2021430176A1

AU2021430176A1 - Rotating electric machine and dump truck rotating electric machine system using same

Info

Publication number: AU2021430176A1
Application number: AU2021430176A
Authority: AU
Inventors: Katsuhiko Fujii; Daisuke Kori; Misato Sato; Shinji Sugimoto; Osamu Tsuchitani
Original assignee: Hitachi Industrial Products Ltd
Current assignee: Hitachi Industrial Products Ltd
Priority date: 2021-02-25
Filing date: 2021-10-15
Publication date: 2023-08-24
Anticipated expiration: 2041-10-15
Also published as: JP2022129702A; WO2022180922A1; JP7458339B2; AU2021430176B2

Abstract

This rotating electric machine is for reducing wear and deformation caused by the mechanical factors of a brush of an excitation-type rotating electric machine due to brush-type power supply, and for ensuring long-term soundness of the brush. The rotating electric machine comprises: a frame; first and second excitation-type rotating electric machines that are disposed in the frame, and that have different excitation currents; first and second brushes and slip rings that supply an electric current to the respective first and second excitation-type rotating electric machines; a shaft that is fastened to a rotor of each of the first and second excitation-type rotating electric machines, and that rotates together with the rotors; and a bearing that rotatably supports the shaft. The rotating electric machine is characterized in that: the first and second brushes are disposed between the bearing and the first excitation-type rotating electric machine; and the brush having the higher excitation current among the first and second brushes is disposed on the bearing side.

Description

DESCRIPTION TITLE OF INVENTION ROTATING ELECTRIC MACHINE AND DUMP TRUCK ROTATING ELECTRIC MACHINE SYSTEM USING SAME TECHNICAL FIELD OF THE INVENTION

[0001]

The present invention relates to a rotating electric

machine and a dump truck rotating electric machine system

using the same. More specifically, the present invention

relates to a rotating electric machine suitable for one in

which a plurality of excitation-type rotating electric

machines having different excitation currents are disposed

in a frame and to which a brush type is applied as a power

supplying device to each of the excitation-type rotating

electric machines, and to a dump truck rotating electric

machine system using the same.

BACKGROUND ART

[0002]

To reduce greenhouse effect gases, a railroad vehicle,

a construction vehicle, and the like have recently adopted

an electric driving type from a conventional type in which a

diesel engine is driven as a power source. In the case of the electric driving type, the power supply that supplies electric power is a diesel electric generator, which has low fuel consumption and also improves the system efficiency, as compared with the case of the driving by the diesel engine itself.

[00031

For the engine electric generator of the electric

driving type, an excitation-type rotating electric machine

is often adopted, and the excitation-type rotating electric

machine can be controlled by directly passing an excitation

current to the rotor, so that it can be operated at a power

factor of 1.0, and has a higher efficiency than an induction

rotating electric machine.

[0004]

However, the excitation-type rotating electric machine

requires a power supplying device for exciting the rotor.

There are two power supplying device types including: a

brush type using a brush and a slip ring; and an AC exciter

type that passes a DC to the stator side and that provides a

three-phase winding to the rotor, thereby enabling the

excitation current to be passed in non-contact manner. From

the viewpoint of the maintainability, the non-contact AC

exciter type is effective, but the brush type having a

simple configuration and at low cost is also adopted.

[00051

By the way, the excitation-type rotating electric

machine applied for supplying power supply for the railroad

vehicle, the construction vehicle, and the like has two

systems including a power supply for driving the vehicle

body (for traction) and an auxiliary power supply for other

accessories. Since the two systems are completely different

in application, they have specifications in which the

capacities and the electric characteristics of both are

completely different.

[00061

Thus, two excitation-type rotating electric machines

different in capacity and electric characteristics are

disposed in the excitation-type rotating electric machine

frame and two rotors are continuous on the same rotating

shaft, and when the brush type described above is applied,

it is required that the excitation current is supplied to

the two rotors. As a result, the number of brushes is also

twice as compared with the typical configuration having one

excitation-type rotating electric machine.

[00071

Also, in the brush type, there is a disadvantage that

wear and deformation are likely to be caused in the brush

itself, and failure due to the brush is also caused. As

result, a regular inspection and a brush replacing operation

are required, which results in poor maintainability, and further, in the case of the configuration having two excitation-type rotating electric machines, they also have different excitation currents, with the result that a difference is caused also in the brush wear amount or the like according to the operation patterns or the like of the excitation-type rotating electric machines, and thus, a difference is caused also in the failure risk.

[00081

Therefore, it is necessary to reduce the brush wear

amount, the deformation, and the failure risk in the brush

type in the configuration having two excitation-type

rotating electric machines.

[00091

From such a thing, a configuration that solves the

above disadvantage when the brush type is used as the power

supplying device of the configuration having two excitation

type rotating electric machines has been studied, and as the

related art document thereof, for example, Patent Document 1

is given.

[0010]

In Patent Document 1 described above, the

configuration has two electric generators, the respective

power supplying devices are of the brush type, one of the

electric generators is used for battery supply, and the

other electric generator is used to supply electric power to a driving electric motor. The excitation current of the electric generator for battery supply is current controlled so as to be smaller than the excitation current of the electric generator that supplies electric power to the electric motor.

DOCUMENT LIST PATENT DOCUMENT

[0011]

Document 1: JP 2009-274629

SUMMARY OF INVENTION TECHNICAL PROBLEM

[0012]

Patent Document 1 described above illustrates the

configuration of the interior of each of the electric

generators in addition to the system. In particular, Fig. 2

of Patent Document 1 illustrates the configuration in which

the two electric generators are disposed in the frame, the

two electric generators are continuous on the rotation shaft,

and brushes that are the power supplying devices of the

rotors are disposed at two positions, that is, one is

immediately close to the bearing that rotatably supports the

rotation shaft, and the other is near the center in the

axial direction of the rotor.

[0013]

Typically, examples of the factors of the wear and the

deformation of the brush include an electric factor and a

mechanical factor, and in the case of the configuration of

Patent Document 1 described above, it can be considered that

there is a high possibility that the wear and the

deformation of the brush disposed at the center in the axial

direction of the rotor are caused by the mechanical factor.

[0014]

Although described later, it can be considered that

the reason why the distortion of the rotor is the largest in

the position is because the position is farthest from the

rotation support at the bearing.

[0015]

In Fig. 2 of Patent Document 1, the position of the

brush is disposed near the center in the axial direction of

the rotor, so that the influence of the mechanical factor

due to the distortion of the rotor becomes large. In

addition, the configuration of Patent Document 1 is the

configuration in which a difference is provided between the

electric currents that excite the two rotors, but since it

is unclear where the brush to which the electric current is

passed is disposed, the configuration cannot be said to be

the configuration in which the influence of the electric

factor and the mechanical factor due to the current passing is most reduced.

[0016]

As a result, in the configuration described in Patent

Document 1, it should be said that there is a problem in

ensuring long-term soundness of the brush.

[0017]

The present invention has been made in view of the

above points, and an object of the present invention is to

provide a rotating electric machine capable of reducing wear

and deformation caused by the mechanical factors of a brush

of an excitation-type rotating electric machine due to

brush-type power supply, and capable of ensuring long-term

soundness of the brush. Another object of the present

invention is to provide a dump truck rotating electric

machine system using the rotating electric machine.

SOLUTION TO PROBLEM

[0018]

In order to achieve the above object, a rotating

electric machine of the present invention comprises a frame,

a plurality of excitation-type rotating electric machines

that are disposed in the frame and that have different

excitation currents with each other, a power supplying

device having at least a plurality of brushes that supply an

electric current to the respective excitation-type rotating electric machines having different excitation currents, a shaft that is fastened to each of rotors of the excitation type rotating electric machines having different excitation currents and that rotates together with the rotors, and a bearing that rotatably supports the shaft. The plurality of brushes that supply the electric current to the respective excitation-type rotating electric machines having different excitation currents are sequentially disposed from the bearing toward a center in an axial direction in a decreasing order of the excitation currents.

Alternatively, a rotating electric machine of the

present invention comprises a frame, first and second

excitation-type rotating electric machines that are disposed

in the frame and that have different excitation currents

with each other, first and second brushes and slip rings

that supply an electric current to the respective first and

second excitation-type rotating electric machines, a shaft

that is fastened to each of rotors of the first and second

excitation-type rotating electric machines and that rotates

together with the rotors, and a bearing that rotatably

supports the shaft. The first and second brushes are

disposed between the bearing and the first excitation-type

rotating electric machine, and a brush having the higher

excitation current of the first and second brushes is

disposed on the bearing side.

[0019]

Further, in order to achieve the above object, a dump

truck rotating electric machine system comprises a blower

for cooling a first excitation-type rotating electric

machine, a second excitation-type rotating electric machine,

an engine, a converter, and a driving rotating electric

machine. The engine is driven to cause the first and second

excitation-type rotating electric machines to generate

electric power, the electric power being supplied through

the converter. The first and second excitation-type

rotating electric machines are the rotating electric

machines having the above configuration.

ADVANTAGEOUS EFFECTS OF INVENTION

[0020]

According to the present invention, it is possible to

reduce wear and deformation caused by the mechanical factors

of a brush of an excitation-type rotating electric machine

due to brush-type power supply, and to ensure long-term

soundness of the brush.

BRIEF DESCRIPTION OF DRAWINGS

[0021]

Fig. 1 is an overall configuration diagram

illustrating a first embodiment of a rotating electric machine of the present invention;

Fig. 2 is a cross-sectional view illustrating a cross

section taken along line A-A' of Fig. 1 and illustrating one

of 8 poles;

Fig. 3 is a cross-sectional view illustrating a cross

section taken along line B-B' of Fig. 1 and illustrating one

of 10 poles;

Fig. 4 is an enlarged diagram illustrating the

vicinity of a power supplying device of Fig. 1;

Fig. 5 is a diagram for explaining a relationship

between the support point and the distortion in a rotor,

which is a mechanical factor;

Fig. 6 is a characteristic diagram for explaining the

relationship between the current density and the brush wear

amount, which is an electric factor;

Fig. 7 is a diagram illustrating a second embodiment

of the rotating electric machine of the present invention

and enlargedly illustrating the vicinity of the power

supplying device;

Fig. 8 is a diagram illustrating a third embodiment of

the rotating electric machine of the present invention and

enlargedly illustrating the vicinity of the power supplying

device;

Fig. 9A is a diagram for explaining the insulation

relationship between a rod and a zero-phase brush in the second embodiment of Fig. 7;

Fig. 9B is a diagram for explaining the insulation

relationship between the rod and the zero-phase brush in the

third embodiment of Fig. 8;

Fig. 10 is an overall configuration diagram

illustrating a fourth embodiment of the rotating electric

machine of the present invention;

Fig. 11 is a cross-sectional view illustrating a cross

section taken along line C-C' of Fig. 10 and illustrating

one of 10 poles;

Fig. 12 is a diagram illustrating a fifth embodiment

of the rotating electric machine of the present invention

and enlargedly illustrating the vicinity of the power

supplying device;

Fig. 13 is a diagram illustrating a sixth embodiment

of the rotating electric machine of the present invention

for explaining the axial direction width dimension

relationship between a slip ring and a brush;

Fig. 14 is a diagram illustrating a seventh embodiment

of the rotating electric machine of the present invention,

seeing the power supplying device from the axial direction;

Fig. 15 is a diagram illustrating an eighth embodiment

of the rotating electric machine of the present invention

and enlargedly illustrating the power supplying device; and

Fig. 16 is a configuration diagram of a ninth embodiment of the present invention illustrating a dump truck rotating electric machine system.

Description of Embodiments

[0022]

Hereinbelow, a rotating electric machine and a dump

truck rotating electric machine system using the same of the

present invention will be described based on illustrated

embodiments.

First Embodiment

[0023]

Fig. 1 illustrates the overall configuration of a

first embodiment of a rotating electric machine 100 of the

present invention, the rotating electric machine 100 being

mainly used by being connected to an engine. The rotating

electric machine 100 of the present embodiment is a rotating

electric machine having a rotation speed of several thousand

min-1 class, and is applied as a power supply for a large

dump truck.

[0024]

As illustrated in Fig. 1, a first excitation-type

rotating electric machine 2, a second excitation-type

rotating electric machine 3, a rotor 4 of the first

excitation-type rotating electric machine 2, a rotor 6 of the second excitation-type rotating electric machine 3, a stator 5 of the first excitation-type rotating electric machine 2, a stator 7 of the second excitation-type rotating electric machine 3, and a power supplying device 8 for passing an excitation current to each of the rotor 4 of the first excitation-type rotating electric machine 2 and the rotor 6 of the second excitation-type rotating electric machine 3 are disposed in a frame 1.

[0025]

A rotor coil end 39a and a stator coil end 39b are

protruded at the end portions in the axial direction of the

rotor 4 and the stator 5 of the first excitation-type

rotating electric machine 2, a rotor coil end 40a and a

stator coil end 40b are protruded at the end portions in the

axial direction of the rotor 6 and the stator 7 of the

second excitation-type rotating electric machine 3, and a

bearing 9 for the rotation of the rotor 4 of the first

excitation-type rotating electric machine 2 and the rotor 6

of the second excitation-type rotating electric machine 3 is

provided in the frame 1 so as to rotatably support a shaft

10 to which the rotor 4 and the rotor 6 are fitted.

[0026]

In Fig. 1, as described above, the side where the

bearing 9 for the connection with the engine is not present

is supported by the bearing (not illustrated) on the engine side (the right side of Fig. 1). Needless to say, there is no problem even when the bearings 9 are provided on both sides of the rotating electric machine 100 to thereby rotatably support the shaft 10.

[0027]

A flow inlet 11 into which a coolant is made to flow

is formed in the frame 1 of Fig. 1, and although described

later, a coolant 12 that enters the flow inlet 11 is sent by

a blower 301 (see Fig. 16) that is disposed separately from

the rotating electric machine 100. The coolant 12 flows in

the right direction of Fig. 1 from the flow inlet 11, and is

made to flow out to the atmosphere (release), as indicated

by the arrows.

[0028]

Fig. 2 is a cross-sectional view illustrating a cross

section taken along line A-A' of Fig. 1 and illustrating one

of 8 poles.

[0029]

As illustrated in Fig. 2, the first excitation-type

rotating electric machine 2 is schematically configured of,

as main components that configure the rotor 4 and the stator

5 of the first excitation-type rotating electric machine 2,

a rotor iron core 13, a stator iron core 14 that is disposed

to face the rotor iron core 13 with a predetermined gap 17

in the radial direction, a field coil 15 that is wound around the rotor iron core 13, stator coils 16 that are wound around the slots of the stator iron core 14, a pole shoe 18 that is disposed at the head portion of the rotor iron core 13, and stator wedges 19 that fix the stator coils

16 that are wound around the slots of the stator iron core

14.

[00301

The rotor iron core 13 and the pole shoe 18 of the

first excitation-type rotating electric machine 2 are

connected by a bolt or a dovetail structure, the fixing

portions of the stator 5 and the frame 1 are positioned with

a predetermined interval in the circumferential direction,

and a back surface duct 20 of the first excitation-type

rotating electric machine 2 for making flow the coolant 12

in the axial direction is provided in the frame 1 between

the fixing portions.

[0031]

Fig. 3 is a cross-sectional view illustrating a cross

section taken along line B-B' of Fig. 1 and illustrating one

of 10 poles.

[0032]

As illustrated in Fig. 3, the second excitation-type

rotating electric machine 3 is schematically configured of,

as main components that configure the rotor 6 and the stator

7 of the second excitation-type rotating electric machine 3, a rotor iron core 21, a stator iron core 22 that is disposed to face the rotor iron core 21 with a predetermined gap 25 in the radial direction, field coils 23 that are wound around the slots of the rotor iron core 21, stator coils 24 that are wound around the slots of the stator iron core 22, damper bars 26 that are provided at the head portion of the rotor iron core 21 between the portions of the field coils

23 in the circumferential direction, rotor wedges 27 that

fix the field coils 23 that are wound around the slots of

the rotor iron core 21, and stator wedges 28 that fix the

stator coils 24 that are wound around the slots of the

stator iron core 22.

[00331

An axial duct 29 for making flow the coolant 12 in the

axial direction is provided on the inner diameter side of

the rotor iron core 21 of the second excitation-type

rotating electric machine 3, the fixing portions of the

stator 7 and the frame 1 are positioned with a predetermined

interval in the circumferential direction, and a back

surface duct 30 of the second excitation-type rotating

electric machine 3 for making flow the coolant 12 in the

axial direction is provided between the fixing portions.

[0034]

Therefore, the coolant 12 that flows from the flow

inlet formed in the frame 1 is made to flow in the order of the power supplying device 8 and the ventilation passage of the first excitation-type rotating electric machine 2 (the gap 17 and the back surface duct 20), and is then made to flow through the ventilation passage of the second excitation-type rotating electric machine 3 (the gap 25, the axial duct 29, and the back surface duct 20) to be discharged into the atmosphere.

[00351

As described in the background art, the rotating

electric machine 100 of the present embodiment has the

configuration having two excitation-type rotating electric

machines for the auxiliary power supply and the driving

power supply (hereinafter, referred to as a main power

supply). The power supply capacity has the relationship in

which the auxiliary power supply < the main power supply,

the auxiliary power supply is several hundred kVA, and the

main power supply is several thousand kVA. Since both of

the excitation-type rotating electric machines rotate at the

same rotation speed on the same shaft, the excitation-type

rotating electric machine having the larger capacity

increases also in the physical size, and likewise, the

excitation-type rotating electric machine having the larger

capacity increases also in the excitation current of the

rotor.

[00361

Considering this phenomenon, as is also apparent from

Fig. 1, the first excitation-type rotating electric machine

2 is the auxiliary power supply, and the second excitation

type rotating electric machine 3 is the main power supply.

The excitation current magnitude also has the relationship

in which the rotor 4 of the first excitation-type rotating

electric machine 2 < the rotor 6 of the second excitation

type rotating electric machine 3.

[0037]

Fig. 4 enlargedly illustrates the power supplying

device 8 for passing the excitation current to each of the

rotor 4 of the first excitation-type rotating electric

machine 2 and the rotor 6 of the second excitation-type

rotating electric machine 3.

[0038]

As illustrated in Fig. 4, the power supplying device 8

includes slip rings 31, brushes 32, brush holders 33, and a

rod 34.

[0039]

Although not illustrated, the exciting power supply

and the brush 32 are connected, and the excitation current

is supplied to each of the rotor 4 of the first excitation

type rotating electric machine 2 and the rotor 6 of the

second excitation-type rotating electric machine 3 by the

sliding contact between the brush 32 and the slip ring 31.

The brush 32 is stored in the brush holder 33, and the brush

holder 33 is fixed into the frame 1 by the rod 34. The rod

34 is usually subjected to an insulation process to prevent

the short-circuit between the brushes.

[0040]

As illustrated in Fig. 4, at the contact points for

the excitation current supply, two sets of first brushes 35a

and second brushes 35b are disposed such that each set has a

pair of the positive and the negative poles of the electric

current, and all the dimensions, shapes, or materials of the

first brush 35a are the same as those of the second brush

35b brush. The excitation current is supplied from the

second brush 35b to the rotor 6 of the second excitation

type rotating electric machine 3, or is supplied from the

first brush 35a to the rotor 4 of the first excitation-type

rotating electric machine 2.

[0041]

That is, the second brush 35b having the larger

excitation current (the current density of the brush is

higher) is disposed immediately close to the bearing 9, and

the first brush 35a having the smaller excitation current is

disposed on the center side in the axial direction.

[0042]

In such the disposition of the brushes 32, it can be

said that the disposition of the present embodiment is best from the relationship between the electric factor and the mechanical factor with respect to the brushes 32.

[0043]

Fig. 5 illustrates the relationship between the

support point and the distortion in the rotor, which is the

mechanical factor.

[0044]

As illustrated in Fig. 5, the rotor is distorted by

rotation, and the rotational member concentrates onto the

vicinity of the center in the axial direction from the

qualitative configuration of the excitation-type rotating

electric machine.

[0045]

That is, since the rotating deadweight concentrates

onto the vicinity of the center in the axial direction, the

distortion amount also becomes large. Even if it is

considered that the rotor has the uniform rotation diameter,

the distortion amount at the position farthest from the

rotation support (bearing) becomes large. Thus, as

illustrated in Fig. 5, the distortion at the center in the

axial direction is maximum, and the distortion amount

becomes smaller toward the rotation support (bearing).

[0046]

Considering thisphenomenon, it can be said that the

second brush 35b that is disposed on the center side in the axial direction illustrated in Fig. 4 has the largest influence due to the distortion of the rotor. By the distortion of the rotor, the second brush 35b experiences an action to be hit by the slip ring 31. By this action, the first brush 35a that is disposed on the center side in the axial direction is likely to cause wear and deformation. On the contrary, the second brush 35b that is disposed immediately close to the bearing 9 has the smaller influence.

[0047]

From this, since the influence of the mechanical

factor is different according to the disposing order of the

brushes 32, a difference is caused in the failure risk due

to the wear amounts and the deformation of the brushes 32.

[0048]

Fig. 6 illustrates the relationship between the

current density and the brush wear amount, which is the

electric factor.

[0049]

As illustrated in Fig. 6, as the current density

becomes higher, the brush wear amount is non-linearly

increases, as indicated by A in the drawing. The wear due

to the mechanical factor when the above mechanical factor is

neglected becomes only the wear due to the sliding between

the brush 32 and the slip ring 31, and is represented by the

dotted line indicated by B in the drawing. It is known that for the influence on the wear amount with respect to the mechanical factor and the electric factor, the wear amount due to the electric factor is dominant.

[00501

From the relationship between the mechanical factor

and the electric factor described above, by disposing the

second brush 35b having the large excitation current

immediately close to the bearing 9, the risks of abnormal

wear and the deformation of the brush 32 can be reduced, so

that the long-term soundness of the brush 32 can be ensured.

[0051]

It should be noted that the present embodiment

described above has the configuration having two excitation

type rotating electric machines, but when a difference is

caused in the excitation current in the configuration having

a plurality of excitation-type rotating electric machines,

the brushes 32 should be disposed in the decreasing

excitation current order so as to be sequentially disposed

from the position immediately close to the bearing 9 toward

the center side in the axial direction.

[0052]

By making such the configuration of the present

embodiment, the wear and the deformation caused by the

mechanical factor of the brush of the excitation-type

rotating electric machine due to the brush-type power supply can be reduced, and the long-term soundness of the brush can be ensured.

Second Embodiment

[00531

Fig. 7 illustrates a second embodiment of the rotating

electric machine 100 of the present invention.

[0054]

The rotating electric machine 100 of the present

embodiment illustrated in Fig. 7 is an example in which a

zero-phase brush 36 is added to the power supplying device 8

illustrated in Fig. 4.

[00551

That is, as illustrated in Fig. 7, the zero-phase

brush 36 is disposed on the center side in the axial

direction with respect to the power supplying device 8, that

is, on the center side in the axial direction with respect

to the first brush 35a and the second brush 35b.

[00561

The zero-phase brush 36 is provided to electrically

discharge a shaft voltage, and when the electric current by

the shaft voltage is unlikely to be caused or is very small

with respect to the excitation current, the mechanical

factor is dominant for the wear factor of the brush 32, so

that the zero-phase brush 36 is disposed on the center side in the axial direction.

[0057]

Even with such the configuration of the present

embodiment, the same effect as the first embodiment is

obtained.

Third Embodiment

[0058]

Fig. 8 illustrates a third embodiment of the rotating

electric machine 100 of the present invention.

[0059]

Contrary to the second embodiment illustrated in Fig.

7, the rotating electric machine 100 of the present

embodiment illustrated in Fig. 8 is an example in which the

zero-phase brush 36 is disposed immediately close to the

bearing 9.

[0060]

That is, as illustrated in Fig. 8, the zero-phase

brush 36 is disposed on the bearing 9 side with respect to

the power supplying device 8, that is, on the bearing 9 side

with respect to the first brush 35a and the second brush 35b.

When the electric current by the shaft voltage is excessive

and is higher than the excitation current, the zero-phase

brush 36 is disposed immediately close to the bearing 9.

[0061]

Even with such the configuration of the present

embodiment, the same effect as the first embodiment is

obtained.

[0062]

In addition, as illustrated in each of Figs. 7 and 8,

the rotating electric machine of the present embodiment is

provided with an excitation wire connection section 41 for

connecting the slip ring 31, the field coil 15 of the first

excitation-type rotating electric machine 2, and the field

coil 23 of the second excitation-type rotating electric

machine 3 by a lead wire 42, but the excitation wire

connection section 41 has high voltage with respect to the

zero-phase brush 36, so that an insulation distance is

required to be ensured.

[0063]

When the suitable insulation distance cannot be

ensured by the configuration of the second embodiment

illustrated in Fig. 7, the rotating electric machine is made

to have the configuration illustrated in Fig. 8, so that the

distance between the zero-phase brush 36 and the excitation

wire connection section 41 can be long, and the insulation

distance can be ensured.

[0064]

Thus, the excitation wire connection section 41 is

provided at the end portion in the axial direction of the slip ring 31, and the zero-phase brush 36 is disposed at the end portion on the opposite side thereof, which is best in ensuring the insulation distance.

[00651

Further, when the zero-phase brush 36 is provided, as

illustrated in Figs. 9A and 9B, the rod 34 is not required

to be insulated at the portion where the zero-phase brush 36

is disposed. From this, the brush holder 33 that stores the

zero-phase brush 36, and the rod 34 are directly brought

into contact with each other, so that the wiring for the

zero-phase brush 36 is not required.

Fourth Embodiment

[00661

Figs. 10 and 11 illustrate a fourth embodiment of the

rotating electric machine 100 of the present invention.

[0067]

The rotating electric machine 100 of the present

embodiment illustrated in Figs. 10 and 11 is an example in

which ventilation ducts 37a, 37b are added to the second

excitation-type rotating electric machine 3.

[00681

As illustrated in the drawing, in the second

excitation-type rotating electric machine 3, a plurality of

ventilation ducts 37a, 37b have a predetermined interval in the circumferential direction and are extended in the radial direction to be radially disposed, and the coolant 12 flowing from the axial duct 29 is made to flow to the radial direction between the plurality of ventilation ducts 37a and

37b disposed in this way.

[00691

By providing the ventilation ducts 37a and 37b as

described above, the cooling performance of the rotor 6 and

the stator 7 of the second excitation-type rotating electric

machine 3 is improved, and at the same time, the rotor iron

core 21 of the second excitation-type rotating electric

machine 3 in the ventilation ducts 37a and 37b portions is

eliminated (for the forming of the axial duct 29, the rotor

iron core 21 in the ventilation ducts 37a and 37b portions

is eliminated), so that the deadweight near the center in

the axial direction described above is reduced, and the

distortion amount also becomes small, and thus, there is

also an effect of increasing the soundness of the brush 32.

[0070]

It should be noted that in the present embodiment, the

ventilation ducts 37a and 37b are provided in the second

excitation-type rotating electric machine 3, but the same

effect is obtained even when likewise, the ventilation ducts

37a and 37b are provided also in the first excitation-type

rotating electric machine 2.

[00711

Further, in the present embodiment, from the left of

the sheet surface, the power supplying device 8, the first

excitation-type rotating electric machine 2, and the second

excitation-type rotating electric machine 3 are disposed in

that order. As described above, from the capacity

relationship, the second excitation-type rotating electric

machine 3 has the largest physical size, and then, the

physical size decreases in the order of the first

excitation-type rotating electric machine 2 and the power

supplying device 8, so that the flow inlet 11 for the

coolant 12 is formed in the frame 1 on the upper left side

of each drawing.

[0072]

From the viewpoint of the cooling, in consideration of

the flow easiness of the coolant 12, the components are

sequentially disposed in the increasing physical size order

based on the flow inlet 11, so that the coolant 12 easily

flows. This is because since three components including the

first excitation-type rotating electric machine 2, the

second excitation-type rotating electric machine 3, and the

power supplying device 8 are disposed in the frame 1, as the

physical size of the component increases, the ventilation

passage area becomes smaller. In addition, by disposing the

flow inlet 11 in the frame 1 on the upper left side, the coolant 12 can be directly made to flow to the slip ring 31 of the power supplying device 8.

[0073]

In addition, since the electric current is usually

passed to the slip ring 31 and the brush 32, the slip ring

31 and the brush 32 generate heat. The component of the

brush 32 is an alloy of graphite and copper, and on the

other hand, the slip ring 31 is copper, so that also from

the difference in the heat conductivity, directly exposing

the slip ring 31 to the coolant 12 can perform the cooling

more effectively. In other words, it is effective to

provide the flow inlet 11 in the frame 1 at a position

against a position where the brush 32 and the brush holder

33 are disposed.

[0074]

It should be noted that as illustrated in the present

embodiment, the number of poles of the first excitation-type

rotating electric machine 2 is 8, the number of slots of the

stator 5 is 48, the number of poles of the second

excitation-type rotating electric machine 3 is 10, and the

number of slots of the stator 7 is 90, but even when the

number of poles or the number of slots is made different,

the same effect as the present embodiment is obtained.

[0075]

In addition, although also for the rotor shape, the rotor shape of the first excitation-type rotating electric machine 2 is salient and the rotor shape of the second excitation-type rotating electric machine 3 is cylindrical, there is no problem even when they are opposite in the rotor shape or both of them have the same rotor shape. Further, although the excitation current has been described by using the DC (a pair of positive and negative poles), the effect of the present embodiment is obtained even with the type in which a plurality of AC excitation currents are passed.

Fifth Embodiment

[0076]

Fig. 12 illustrates a fifth embodiment of the rotating

electric machine 100 of the present invention.

[0077]

In the rotating electric machine 100 of the present

embodiment illustrated in Fig. 12, the first brushes 35a and

the second brushes 35b in the power supplying device 8 are

disposed such that the slip rings 31 or the brush holders 33

have unequal intervals in the axial direction.

[0078]

That is, in the power supplying device 8 of the

present embodiment, when the interval in the axial direction

between the slip rings 31 (which may be the brush holders

33) of the second brushes 35b is W1, the interval in the axial direction between the slip rings 31 (which may be the brush holders 33) of the first brushes 35a is W2, and the interval in the axial direction between the slip rings 31

(which may be the brush holders 33) of the first brush 35a

and the second brush 35b is W3, the first brushes 35a and

the second brushes 35b are disposed so as to have the

relationship in which W1 > W2, W3 > W1.

[0079]

Typically, as described in the first embodiment, since

the second brush 35b has the larger excitation current than

the first brush 35a, the second brush 35b increases also in

the temperature. Thus, the cooling performance is required

to be high.

[0080]

Since the interval in the axial direction between the

slip rings 31 or the brush holders 33 of the brushes 32

having the larger excitation current is made larger

similarly to the present embodiment, the coolant 12 is

easily made to flow in the gap, and the cooling performance

can be improved. In addition, the fixed and adhered dust

caused by the wearing of the second brush 35b can also be

easily discharged by the coolant 12.

Sixth Embodiment

[0081]

Fig. 13 illustrates a sixth embodiment of the rotating

electric machine 100 of the present invention.

[0082]

In the rotating electric machine 100 of the present

embodiment illustrated in Fig. 13, the axial direction width

(Li) of the slip ring 31 is made larger than the axial

direction width (L2) of the brush 32.

[0083]

Since the axial direction width (Li) of the slip ring

31 is made larger than the axial direction width (L2) of the

brush 32, the contact between the slip ring 31 and the brush

32 can be ensured also with respect to displacement due to

the vibration in the axial direction or the like of the

brush 32 and the variation in assembling (for the axial

direction width (Li) of the slip ring 31 being larger than

the axial direction width (L2) of the brush 32, the contact

with the brush 32 is ensured).

[0084]

In addition, since the surface area of the slip ring

31 itself becomes large, the heat transmission area of the

coolant 12 also becomes large, so that the cooling

performance can be improved.

Seventh Embodiment

[0085]

Fig. 14 illustrates a seventh embodiment of the

rotating electric machine 100 of the present invention.

[00861

In the first to third embodiments described above, the

first and second brushes 35a and 35b and the brush holder 33

are disposed at the same position in the circumferential

direction with respect to the rod 34 of the power supplying

device 8, and they are arranged in a row in the direction

seen from Fig. 14 (in the axial direction) (that is, the

first and second brushes 35a and 35b and the brush holder 33

are overlapped in the axial direction). However in the

present embodiment illustrated in Fig. 14, the first brush

35a and the second brush 35b are separated and are disposed

at different positions with each other in the

circumferential direction.

[0087]

This separates the deadweight added to one rod 34, so

that the vibration of the rod 34 itself is suppressed and

the reliability can be improved.

[00881

In addition, in the present embodiment, the ground

side is on the below side, and in the arrangement of the

brushes 32 and the brush holders 33, the second brush 35b is

disposed between the 3 o'clock and the 6 o'clock directions,

and the first brush 35a is disposed between the 6 o'clock and the 9 o'clock directions.

[00891

When windows for the regular inspection or the brush

replacement are provided in the frame 1 at the positions of

the 3 o'clock and the 9 o'clock of Fig. 14, the disposition

of the first brush 35a and the second brush 35b described

above allows the whole of the brush 32 and the brush holder

33 to be easily visibly confirmed during the maintenance, so

that the operativity of the replacement of the brush 32 is

also improved.

Eighth Embodiment

[00901

Fig. 15 illustrates an eighth embodiment of the

rotating electric machine 100 of the present invention.

[0091]

In the rotating electric machine 100 of the present

embodiment illustrated in Fig. 15, a plurality of grooves 38

are helically provided on the surface of the slip ring 31 in

which the first brush 35a and the second brush 35b are

brought into contact with each other (the outer

circumference surface).

[0092]

Like the present embodiment, the plurality of grooves

38 are helically provided on the surface of the slip ring 31 in which the first brush 35a and the second brush 35b are brought into contact with each other (the outer circumference surface), so that the electric current unbalance on the contact surface of the brush 32 can be made uniform. In addition, since the plurality of helical grooves 38 are provided on the contact surface of the slip ring 31 in which the first brush 35a and the second brush

35b are brought into contact with each other, the cooling

performance of the contact portion is also improved.

Ninth Embodiment

[00931

Fig. 16 illustrates, as a ninth embodiment of the

present invention, the rotating electric machine 100 of each

of the embodiments described above is applied to a dump

truck rotating electric machine system.

[0094]

As illustrated in Fig. 16, in the dump truck rotating

electric machine system of the embodiment, one of the

rotating electric machines 100 described in the first to

eighth embodiments is directly connected to an engine 200

through a coupling 50. The engine 200 is driven, so that

electric power is supplied from the rotating electric

machine 100 to power converters 201a and 201b. The power

converter 201a supplies the electric power to a driving rotating electric machine 300 of dump truck. On the other hand, the power converter 201b supplies the electric power for the auxiliary machine, such as the blower 301, making flow the coolant 12 for cooling the rotating electric machine 100.

[00951

By making such the configuration of the present

embodiment, the rotating electric machine 100 can reduce the

wear and the deformation caused by the mechanical factors of

the brush 32 of the first and second excitation-type

rotating electric machines 2 and 3 due to the brush-type

power supply, and can ensure the long-term soundness of the

brush, so that it is effective for the dump truck rotating

electric machine system.

[00961

It should be noted that the present invention is not

limited to the embodiments described above, and includes

various modification embodiments. For example, the

embodiments described above have been described in detail to

simply describe the present invention, and are not

necessarily required to include all the described

configurations. In addition, part of the configuration of

one embodiment can be replaced with the configurations of

other embodiments, and in addition, the configuration of the

one embodiment can also be added with the configurations of other embodiments. In addition, part of the configuration of each of the embodiments can be subjected to addition, deletion, and replacement with respect to other configurations.

LIST OF REFERENCE CHARACTERS

[0097]

1: frame,

2: first excitation-type rotating electric machine,

3: second excitation-type rotating electric machine,

4: rotor of first excitation-type rotating electric

machine,

5: stator of first excitation-type rotating electric

machine,

6: rotor of second excitation-type rotating electric

machine,

7: stator of second excitation-type rotating electric

machine,

8: power supplying device,

9: bearing,

10: shaft,

11: flow inlet,

12: coolant,

13: rotor iron core of first excitation-type rotating

electric machine,

14: stator iron core of first excitation-type rotating

electric machine,

15: field coil of first excitation-type rotating

electric machine,

16: stator coil of first excitation-type rotating

electric machine,

17: gap of first excitation-type rotating electric

machine,

18: pole shoe,

19: stator wedge of first excitation-type rotating

electric machine,

20: back surface duct of first excitation-type

rotating electric machine,

21: rotor iron core of second excitation-type rotating

electric machine,

22: stator iron core of second excitation-type

rotating electric machine,

23: field coil of second excitation-type rotating

electric machine,

24: stator coil of second excitation-type rotating

electric machine,

25: gap of second excitation-type rotating electric

machine,

26: damper bar,

27: rotor wedge of second excitation-type rotating electric machine,

28: stator wedge of second excitation-type rotating

electric machine,

29: axial duct,

30: back surface duct of second excitation-type

rotating electric machine,

31: slip ring,

32: brush,

33: brush holder,

34: rod,

35a: first brush,

35b: second brush,

36: zero-phase brush,

37a, 37b: ventilation duct,

38: helical groove,

39a: rotor coil end of rotor of first excitation-type

rotating electric machine,

39b: stator coil end of stator of first excitation

type rotating electric machine,

40a: rotor coil end of rotor of second excitation-type

rotating electric machine,

40b: stator coil end of stator of second excitation

type rotating electric machine,

41: excitation wire connection section,

42: lead wire,

50: coupling,

100: rotating electric machine,

200: engine,

201a, 201b: power converter,

300: driving rotating electric machine of dump truck,

301: blower

Claims

WHAT IS CLAIMED IS:

1. A rotating electric machine comprising:

a frame;

a plurality of excitation-type rotating electric

machines that are disposed in the frame and that have

different excitation currents with each other;

a power supplying device having at least a plurality

of brushes that supply an electric current to the respective

excitation-type rotating electric machines having different

excitation currents;

a shaft that is fastened to each of rotors of the

excitation-type rotating electric machines having different

excitation currents and that rotates together with the

rotors; and

a bearing that rotatably supports the shaft,

wherein the plurality of brushes that supply the

electric current to the respective excitation-type rotating

electric machines having different excitation currents are

sequentially disposed from the bearing toward a center in an

axial direction in a decreasing order of the excitation

currents.

2. A rotating electric machine comprising:

a frame;

first and second excitation-type rotating electric machines that are disposed in the frame and that have different excitation currents with each other; first and second brushes and slip rings that supply an electric current to the respective first and second excitation-type rotating electric machines; a shaft that is fastened to each of rotors of the first and second excitation-type rotating electric machines and that rotates together with the rotors; and a bearing that rotatably supports the shaft, wherein the first and second brushes are disposed between the bearing and the first excitation-type rotating electric machine, and a brush having the higher excitation current of the first and second brushes is disposed on the bearing side.

3. The rotating electric machine according to claim 2,

wherein the first excitation-type rotating electric

machine is an auxiliary excitation-type rotating electric

machine, and the second excitation-type rotating electric

machine is a main excitation-type rotating electric machine,

and

wherein the first brush is for the auxiliary

excitation-type rotating electric machine, and the second

brush is for the main excitation-type rotating electric

machine.

4. The rotating electric machine according to claim 3,

wherein the auxiliary excitation-type rotating

electric machine, the main excitation-type rotating electric

machine, the first brush, and the second brush are disposed

on the shaft from the bearing in an order of the second

brush, the first brush, the auxiliary excitation-type

rotating electric machine, and the main excitation-type

rotating electric machine.

5. The rotating electric machine according to any one of

claims 2 to 4,

wherein the first and second brushes have a same shape,

a same dimension, and a same material with each other.

6. The rotating electric machine according to claim 4,

wherein a zero-phase brush that electrically

discharges a shaft voltage is disposed on the shaft on a

center side in the axial direction or a bearing side with

respect to the first and second brushes.

7. The rotating electric machine according to any one of

claims 2 to 6,

wherein the first and second excitation-type rotating

electric machines include an axial duct on an inner diameter side of a rotor iron core, the axial duct flowing a coolant in the axial direction, wherein the first and second excitation-type rotating electric machines include a plurality of ventilation ducts at a predetermined interval in a circumferential direction, the ventilation ducts extended in a radial direction to be radially disposed, and wherein the coolant that flows from the axial duct is made to flow in the radial direction between the plurality of ventilation ducts.

8. The rotating electric machine according to any one of

claims 2 to 7,

wherein the frame includes a flow inlet that guides a

coolant into an interior of the rotating electric machine,

and

wherein the flow inlet is provided at a position

facing a position where the first and second brushes and

brush holders that hold the first and second brushes are

disposed.

9. The rotating electric machine according to claim 8,

wherein the first and second brushes are disposed such

that the slip rings or the brush holders have unequal

intervals with each other in the axial direction.

10. The rotating electric machine according to claim 9,

wherein when an interval in the axial direction

between the slip rings or the brush holders of the second

brushes is W1, an interval in the axial direction between

the slip rings or the brush holders of the first brushes is

W2, and an interval in the axial direction between the slip

rings or the brush holders of the first brush and the second

brush is W3, the first and second brushes are disposed to

have a relationship of W1 > W2, W3 > W1.

11. The rotating electric machine according to any one of

claims 2 to 10,

wherein an axial direction width of the slip ring is

larger than an axial direction width of the first and second

brushes.

12. The rotating electric machine according to any one of

claims 2 to 11,

wherein the first brush and the second brush are

disposed at different positions with each other in a

circumferential direction.

13. The rotating electric machine according to any one of

claims 2 to 12, wherein a plurality of helical grooves are provided on a surface of the slip ring, the first and second brushes coming into contact with the surface.

14. A dump truck rotating electric machine system

comprising:

a blower for cooling a first excitation-type rotating

electric machine, a second excitation-type rotating electric

machine, an engine, a converter, and a driving rotating

electric machine,

wherein the engine is driven to cause the first and

second excitation-type rotating electric machines to

generate electric power, the electric power being supplied

through the converter,

wherein the first and second excitation-type rotating

electric machines are the rotating electric machine

according to any one of claims 2 to 13.