JP3288206B2 - Rotating electric machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling structure for a bearing and a housing of a rotary electric machine, and more particularly to a cooling structure suitable for a self-cooling general-purpose induction motor of an external fan.

[0002]

2. Description of the Related Art As shown in FIG. 5, a rotary electric machine such as a general-purpose induction motor has a stator (stator) 1 composed of a stator core and a stator winding, and a substantially cylindrical housing. 4 and end brackets 6a and 6b are attached to both ends of the housing 4 by inlay (fitting), and usually fastened at three or four places on one side with bolts 10, and the rotor core and the cage A shaft (rotating shaft) 5 having a rotor (rotor) 2 composed of windings at a substantially central portion is inserted. Near both ends of the shaft 5, an end bracket 6a is inserted through a bearing 3 formed of a ball bearing. Conventionally, a structure in which the support is provided is common.

The rotating electric machine shown in FIG. 5 is an induction motor of an external fan fan self-cooling type. Therefore, at one end of the shaft 5, an external fan 8 for cooling is mounted.
An end cover 9 is provided so as to cover the outer fan 8, thereby generating a flow of cooling air as shown by a solid line A, and cooling fins (radiation fins) 4 a provided on the outer peripheral surface of the housing 4. The cooling air flows along the end bracket 6b, and reaches the surface of the end bracket 6b by a forced guide 7 provided so as to cover the end bracket 6b.

By the way, in such a rotating electric machine, loss occurs in the stator 1 and the rotor 2 during operation, and heat is generated from the stator 1 and the rotor 2. One type is transmitted from the stator 1 to the housing 4 as shown by a broken line a in the figure,
Further, after flowing into the cooling fins 4a, the heat is radiated by the cooling air generated by the outer fan 8 and the other is transmitted from the rotor 2 to the shaft 5 as shown by a broken line B in the drawing.
The cooling air flows through the bearing 3 to the end bracket 6a, passes from the outer fan 8 to the space between the cooling fins 4a on the outer peripheral surface of the housing 4, and is guided by the forced guide 7 to reach the outer surface of the end bracket 6a. The heat is radiated as shown by the arrow B.

In the induction motor shown in FIG. 5, a foot (leg member) for installing the motor is formed as a separate member from the housing 4, and the separately formed foot 4c is bolted to the housing 4 as shown in FIG. It is designed to be mounted with nuts.
At this time, as a method of attaching the foot 4c to the housing 4, for example, a method disclosed in German Patent Application Publication No. 2327525 is used.

More specifically, as shown in FIG. 3, the housing 4 is provided with two foot mounting ribs 4b substantially at right angles to each other, and the foot 4c is engaged between the ribs 4b. Then, bolts are inserted into the mounting holes provided in the feet 4c and the mounting holes provided in the ribs 4b so as to be fitted thereto, and the nuts 4d are fitted and tightened in the bolts, whereby the feet 4c are connected to the housing 4. It is attached to.

At this time, in this prior art, as shown in an enlarged view in FIG. 6, the rib 4b is brought into contact with both side surfaces of the nut 4d so that the nut holding seat 4
e is provided to prevent the nut 4d from idling when the bolt is tightened, so that the mounting operation can be easily performed.

[0008]

However, the prior art described above does not sufficiently consider the improvement of cooling efficiency, and has a problem in extending the life of a bearing of a rotating electric machine.
In other words, the bearing of the rotating electric machine uses grease for lubrication and rust prevention, so when the temperature of the bearing rises,
The grease inside the bearing deteriorates quickly, shortening the service life.
However, in the prior art, sufficient cooling of the bearing cannot be obtained, and the temperature of the bearing tends to be high, which causes a problem in extending the life of the bearing.

An object of the present invention is to provide a rotating electric machine capable of sufficiently suppressing a rise in temperature of a bearing and easily obtaining a long life.

[0010]

An object of the present invention is to provide a stator in which
A substantially cylindrical housing held at the periphery and this housing
Attached to both ends of the rotor to support the rotating shaft of the rotor.
Two end brackets with mounted bearings
And mounted almost radially on the outer peripheral surface of the housing
To the radiating fins
To allow cooling air to flow, take one end of the rotating shaft.
In a rotating electric machine having an attached external fan,
Mounting joint of the end bracket to the housing
Filler made of semi-fluid material is applied to the contact surface of
It is achieved as there. At this time, the filler is
It may be a silicon compound, as described above.
A filler material may be mixed in the filler.
Further, at this time, the housing is provided with a rib for attaching a leg member.
The mounting leg is secured to this rib with bolts and nuts.
The rib is attached to it and one of the radiating fins.
It has a nut press seat located between
The above nut is held by the seat,
The nut holder is for one of the above radiating fins.
Alternatively, a gap may be formed.

[0011]

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a rotating electric machine according to the present invention will be described in detail with reference to embodiments. FIG. 1 is an enlarged view of a connecting portion between a housing 4 and an end bracket 6a of a rotary electric machine according to an embodiment of the present invention. In this drawing, D denotes a contact at a connecting portion between the housing 4 and the end bracket 6a. FIG. Here, the unevenness existing there is exaggeratedly drawn.

Here, the rotating electric machine according to this embodiment is an induction motor of an external fan self-cooling type similarly to the rotating electric machine described with reference to FIG. 5, so that the bearing 3, the housing 4, the shaft 5, the end bracket 6a are provided. , The bolts 10 and the like are not particularly different from the rotating electric machine shown in FIG. 5 and have almost the same overall structure. However, in the embodiment of FIG. 1, before the assembly of the housing 4 and the end bracket 6a, The contact surfaces D of both the housing 4 and the bracket 6a
In addition, a filler made of a semi-fluid material having a good thermal conductivity is applied in advance.

Also in this embodiment, the housing 4 and the end bracket 6a are connected and fastened with the bolts 10 to assemble them. Is applied, after the housing 4 and the end bracket 6a are assembled, a filler is interposed between the contact surfaces D of the joint portion. As a result, as shown in the drawing, the contact surface D Even if there are irregularities, the filler is buried in the gaps due to the irregularities so that no void remains.

On the other hand, in the rotating electric machine according to this embodiment, that is, a self-cooling type rotating electric machine using an external fan, as is apparent from FIG. 5, the cooling air from the external fan 8 is guided to the cooling fins 4a to radiate heat. Is promoted, the amount of heat radiated from the housing 4 is considerably larger than the amount of heat radiated from the end bracket 6a. As a result, the housing 4 is sufficiently cooled and the end bracket 6a is cooled. Will be kept at a lower temperature.

As described above, when the temperature of the housing 4 is lower than the temperature of the end bracket 6a,
Since the heat of the end bracket 6a flows out to the housing 4, a rise in the temperature of the end bracket 6a can be suppressed. As a result, a rise in the temperature of the bearing 3 is also suppressed, and the deterioration of the bearing 3 is reduced. As a result, the life can be extended.

However, at this time, the housing 4,
The contact surface D between the end brackets 6a is inevitably uneven, as illustrated in an exaggerated manner in FIG. 1. As a result, there is a slight gap between the contact surfaces D. Since this gap is a layer of air, even if the gap is a small gap, the thermal resistance is considerably large, and therefore, heat transfer from the end bracket 6a to the housing 4 cannot be sufficiently obtained. And this is the reason why the temperature of the bearing 3 cannot be suppressed and the life is shortened in the above-described conventional technology.

Here, the contact surface D having such a gap is provided.
The thermal resistance between them decreases as the pressure at the contact surface and the thermal conductivity of the substance interposed between them increase, and as the surface roughness (the size of the irregularities) of the contact surface decreases, the contact resistance decreases. Good heat conduction between D is obtained. The thermal resistance between the contact surfaces can be generally expressed by the following equation.

1 / R = A · P + a · λf / (δ1 + δ2) R: thermal resistance between contact surfaces A, a: constant determined by physical property value P: contact surface pressure λf: thermal conductivity of intervening material on contact surface (δ1 + δ2): the sum of the maximum heights of the respective surface roughnesses. If the thermal conductivity λf of the contact surface intervening material is increased, the thermal resistance between the housing 4 and the end bracket 6a can be reduced under the same conditions. It can be seen that the heat conduction between them can be greatly improved.

At this time, if a grease-like substance having a high viscosity, that is, a filler made of a so-called semi-fluid material is used as the contact surface intervening substance, the thermal conductivity is much higher than that of air. Since it is large and semi-fluid and highly viscous, it can be reliably filled in narrow and fine gaps without leaving any voids.

Therefore, according to the embodiment described with reference to FIG. 1, since the filler is interposed in the contact surface D between the housing 4 and the end bracket 6a, the thermal resistance here is sufficiently reduced. As a result, the heat of the end bracket 6a begins to flow out to the housing 4, so that the temperature rise of the end bracket 6a and, consequently, the temperature rise of the bearing 3 are suppressed, and the deterioration of the bearing 3 is reduced, and the life is shortened. Can be extended.

Incidentally, in such a rotating electric machine, the temperature of the bearing 3 is often a bottleneck in the thermal design of the rotating electric machine. However, according to this embodiment, the temperature rise of the bearing 3 can be sufficiently suppressed, so that the thermal design is facilitated, and the rotary electric machine can be sufficiently reduced in size based on a rational design.

Next, in this embodiment, the housing 4
Before assembling the end bracket 6a and the housing 4
A filler made of a semi-fluid material having a good thermal conductivity to be applied in advance to both contact surfaces D of the end bracket 6a and the end bracket 6a will be described below.

First, various compounds are used as the filler, and in any case, the filler has a higher thermal conductivity than air, so that a sufficient cooling effect can be obtained. Thus, among various compounds, for example, a silicon compound may be used. If a silicon compound is used, the viscosity is always maintained, so that there is no possibility of peeling off from the contact surface D, and a stable and high heat transfer property can be obtained over a long period of time.

Next, a filler further mixed with a filler may be used. This filler is used to increase its thermal conductivity, for example, by mixing it with a filler such as a compound, and is presenting a coarse powder composed of fine short fibrous bodies. Generally, a metal is used, for example, gold, silver, copper, aluminum, or the like. From the viewpoint of thermal conductivity, it is also possible to use a diamond filler.

By using the filler mixed with the filler, it is possible to obtain better heat transfer than the silicon compound, so that the temperature rise of the bearing 3 can be further suppressed. At this time, an adhesive may be used as a filler, and a filler may be mixed therein.

By the way, as is apparent from the above equation,
Since the thermal resistance at the contact surface decreases as the roughness of the contact surface decreases, if the roughness of the contact surface is reduced, the temperature rise of the bearing 3 can be further reduced.

That is, if the joint between the housing 4 and the end bracket 6a is precisely finished by polishing or the like and the surface roughness of the contact surface D between them is sufficiently reduced as shown in FIG. The gap existing between the contact surface D of the end bracket 6a and the end bracket 6a is further reduced, and the thermal resistance during this period can be sufficiently reduced. As a result, the temperature rise of the bearing 3 can be further suppressed.

Also, as is apparent from the above equation, the thermal resistance at the contact surface decreases and decreases as the contact surface pressure increases. Therefore, if the contact surface pressure is increased, the temperature of the bearing 3 will increase. Can be further reduced. That is, the number of bolts 10 used for joining the housing 4 and the end bracket 6a is not three or four as usual, but eight, for example, as shown in FIG. Are increased to eight places and the contact surface pressure between the end bracket 6a and the housing 4 is increased.
a, the thermal resistance between the housing 4 is reduced, and the heat radiation of the end bracket 6a is enhanced, and as a result, the temperature of the bearing 3 can be reduced.

Next, another embodiment of the present invention will be described. In the induction motor shown in FIG.
(Leg member) is made as a separate member from the housing 4, and as shown in the drawing, the separately formed foot 4c is attached to the housing 4 with bolts and nuts. Is the same.

Then, as described above, the housing 4
And two ribs 4 for attaching feet, which are substantially perpendicular to each other.
b, a foot 4c is engaged between these ribs 4b,
A bolt is inserted into a mounting hole provided in the foot 4c and a mounting hole provided in the rib 4b so as to be fitted thereto, and a nut 4d is fitted into the mounting hole and tightened, thereby obtaining the foot 4c.
Is attached to the housing 4. At this time, the rib 4b is provided with a nut holding seat 4e so as to abut on both side surfaces of the nut 4d, and the idling of the nut 4d when tightening the bolt is prevented. Thus, the mounting operation can be easily performed, and this is the same in the embodiment of the present invention.

At this time, in the conventional rotary electric machine, the height of the nut presser seat 4e is larger than the thickness of the nut 4d, as shown in FIG. 5 and FIG. , The cooling fins 4a on the upper side.

That is, in this case, the rib 4b on the mounting side of the foot 4c is made thick as shown in FIG.
(Thick), so the nut retainer 4e
Is straddled between the rib 4b and the cooling fin 4a.

Although not shown, the housing 4 having such a split foot structure often has a structure in which the position of the terminal box is rotated by 90 ° with respect to the load axis to mount the foot 4c. For this reason, the nut holding seats 4e are located at several places, and as shown by an arrow A in FIG.
Therefore, in the conventional rotary electric machine, the cooling of the end bracket 6a on the opposite side of the outer fan 8 (the end bracket opposite to the outer fan) is insufficient. .

Therefore, in the embodiment of the present invention, as shown in FIG. 4, the cooling fins 4a and the ribs 4 for attaching the split feet are provided to increase the cooling air on the surface of the end bracket 6a.
In order to remove the upper part of the nut presser seat 4e provided between the upper and lower cooling fins 4a so as to form a large gap between the upper part and the cooling fin 4a, for example, the nut 4d has a thickness less than the thickness of the nut 4d. I have.

As a result, according to the embodiment of FIG. 3, as shown by the arrow A, a part of the cooling air from the outer fan 8 is deflected by the nut holding seat 4e, while Is also circulated through the upper part of the nut retainer 4e, as also indicated by the arrow A, so that it is possible to partially suppress the ventilation obstruction to the cooling air, and as a result,
Cooling of the bracket 6a is promoted, temperature rise of the bearing 3 is suppressed, and a longer life can be obtained.

In the above description of the embodiment of the present invention, only the cooling of the outer fan side end bracket 6a has been described. However, the same applies to the outer fan side end bracket 6b. The same configuration is applied to the joint portion of the fan-side end bracket 6b to suppress the temperature rise of the bearing 3 provided on the outer fan-side end bracket 6b, similarly to the bearing 3 on the side opposite to the outer fan-side end bracket 6a. And a longer life can be obtained.

[0038]

According to the present invention, the cooling of the end bracket can be improved and the temperature of the bearing can be improved with a simple structure in which a semi-fluid material is interposed at the portion where the housing of the rotating electric machine comes into contact with the end bracket. Since the rise is suppressed, it is possible to easily provide a small-sized and long-life rotating electric machine with almost no increase in cost.

According to the present invention, the pressing member of the foot mounting nut present in the cooling air passage is formed so as to have a gap between the pressing member and the radiation fin on the upper portion thereof. Since the cooling of the end bracket can be improved and the temperature rise of the bearing can be suppressed, a small-sized and long-life rotating electric machine can be easily provided with almost no increase in cost.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view illustrating an embodiment of a rotating electric machine according to the present invention.

FIG. 2 is a partial cross-sectional view for explaining an embodiment of the rotating electric machine according to the present invention.

FIG. 3 is a front view for explaining another embodiment of the rotating electric machine according to the present invention.

FIG. 4 is a partially enlarged view for explaining another embodiment of the rotating electric machine according to the present invention.

FIG. 5 is a side view of a partial cross section showing an example of the rotating electric machine.

FIG. 6 is a partially enlarged view for explaining a conventional example of a rotating electric machine.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Stator (stator) 2 Rotor (rotor) 3 Bearing (ball bearing) 4 Housing 4a Cooling fin 4b Rib for foot attachment 4c Splittable foot (installation leg member) 4d Nut for foot attachment 4e Nut holding seat 5 Shaft (rotating shaft) 6a End bracket on outer fan side 6b End bracket on outer fan 7 Bearing cooling air forced guide 8 External fan 9 End cover 10 Bolt for fastening end bracket and housing

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takeshi Omata 7-1-1 Higashi Narashino, Narashino City, Chiba Prefecture Hitachi, Ltd. Industrial Equipment Division (72) Inventor Takao Komura 7-1-1 Higashi Narashino, Narashino City, Chiba Prefecture No. Hitachi, Ltd.Industrial Equipment Division (72) Inventor Akihiro Sekine 7-1-1 Higashi Narashino, Narashino City, Chiba Prefecture Hitachi, Ltd.Industrial Equipment Division (72) Inventor Takashi Kotani 7-1 Higashi Narashino, Narashino City, Chiba Prefecture No. 1 Hitachi, Ltd. Industrial Equipment Division (72) Inventor Takuya Abe 7-1-1 Higashi Narashino, Narashino City, Chiba Prefecture Hitachi, Ltd. Chome 1-1 Hitachi Industrial Machinery Co., Ltd. Business Unit (72) Inventor Hironobu Tanaka 7-1-1, Higashi Narashino, Narashino City, Chiba Prefecture Hitachi, Ltd.Industrial Equipment Division (72) Inventor Kenji Takahashi 502, Kandachicho, Tsuchiura City, Ibaraki Prefecture Hitachi, Ltd. In-house (56) References JP-A-7-264809 (JP, A) JP-A-60-84827 (JP, U) JP-A-58-153558 (JP, U) JP-A-1-113564 (JP, U) (58) Field surveyed (Int.Cl. ⁷ , DB name) H02K 5/04-5/18 H02K 9/22

Claims (4)

(57) [Claims] 1. A substantially cylindrical housing holding a stator at an inner peripheral portion thereof, and two end brackets mounted on both ends of the housing and bearings for supporting a rotating shaft of a rotor, respectively. , Outer peripheral surface of the housing
Multiple radiation fins that are
To allow cooling air to flow through the radiating fins.
A rotating electric machine having an external fan attached to one end of the rotating shaft, wherein a filler made of a semi-fluid material is applied to a contact surface of the mounting joint of the end bracket with respect to the housing. A rotating electric machine characterized by: 2. The rotating electric machine according to claim 1, wherein the filler is a silicon compound. 3. The rotating electric machine according to claim 1, wherein a filler material is mixed in the filler. 4. The invention according to claim 1, wherein the housing has a rib for mounting a leg member,
A mounting leg member is attached to the mounting bolts and nuts, and the rib is positioned between the rib and one of the radiating fins.
The nut holder is provided with
And the nut is held, and the nut holding seat corresponds to one of the radiation fins .
A rotating electric machine, wherein a gap is formed.