JP6900079B2

JP6900079B2 - Brushless motor

Info

Publication number: JP6900079B2
Application number: JP2020100621A
Authority: JP
Inventors: 土屋　昌久; 昌久土屋
Original assignee: Tokyo Parts Ind Co Ltd
Current assignee: Tokyo Parts Ind Co Ltd
Priority date: 2015-12-10
Filing date: 2020-06-10
Publication date: 2021-07-07
Anticipated expiration: 2035-12-10
Also published as: JP2020159556A

Description

本発明は含油軸受を用いたブラシレスモータに関する。 The present invention relates to a brushless motor using an oil-impregnated bearing.

プロジェクタ装置のカラーホイールやプリンタ装置のポリゴンミラー等を回転駆動させるスピンドルモータとして、アウターロータ型のブラシレスモータが用いられている。このようなモータでは高精度な回転性能が要求されており、軸受として従来は主に転がり軸受が用いられていたものの、回転騒音の問題や低コスト化の対応が困難であることから、近年、内部に潤滑油を含浸させた多孔質材料製の含油軸受が用いられるようになってきた。 An outer rotor type brushless motor is used as a spindle motor for rotationally driving a color wheel of a projector device, a polygon mirror of a printer device, and the like. Such motors are required to have high-precision rotational performance, and although rolling bearings have been mainly used as bearings in the past, it is difficult to deal with the problem of rotational noise and cost reduction in recent years. Oil-impregnated bearings made of porous materials impregnated with lubricating oil have come to be used.

上記のような含油軸受として、例えば特許文献１には、両端部に軸受部を有した圧粉成形焼結金属体からなるインナー部と、このインナー部を内周面側に同心状に圧入させるアウター部とからなり、アウター部はインナー部より低密度の圧粉焼結金属組織体からなる二重構造の軸受ユニットが記載されている。 As the oil-impregnated bearing as described above, for example, in Patent Document 1, an inner portion made of a dust-molded sintered metal body having bearing portions at both ends and the inner portion are concentrically press-fitted to the inner peripheral surface side. A double-structured bearing unit is described in which the outer portion is composed of an outer portion and the outer portion is composed of a dust-sintered metal structure having a lower density than the inner portion.

特許文献１に記載の含油軸受によれば、インナー部に比してアウター部の潤滑油保持量を増大させることができ、しかもアウター部より密度の高いインナー部の毛管力により良好な密度勾配が形成されてアウター部側からインナー部へと潤滑油が逐次吸引・移動しやすくなる結果、低振動で静粛性に優れ、しかも長寿命化された軸受ユニットが得られるとされている。 According to the oil-impregnated bearing described in Patent Document 1, the amount of lubricating oil retained in the outer portion can be increased as compared with the inner portion, and a good density gradient can be obtained due to the capillary force of the inner portion having a higher density than the outer portion. It is said that as a result of being formed and facilitating the sequential suction and movement of the lubricating oil from the outer portion side to the inner portion, a bearing unit having low vibration, excellent quietness, and a long life can be obtained.

また、特許文献２には、シャフトを回転自在に支持する軸受面となる内周面を有し潤滑剤を含む多孔質材料製の内側軸受と、空孔率が内側軸受よりも高く潤滑剤を含む多孔質材料製の外側軸受とで構成される二重構造の含油軸受を備え、内側軸受の外周面と外側軸受の内周面との間に、外部と連通し、内側軸受の外周面の一部と外側軸受の内周面の一部とによって形成される連通溝が形成された含油軸受機構が記載されている。 Further, Patent Document 2 describes an inner bearing made of a porous material having an inner peripheral surface as a bearing surface that rotatably supports the shaft and containing a lubricant, and a lubricant having a higher porosity than the inner bearing. A double-structured oil-impregnated bearing composed of an outer bearing made of a porous material including the inner bearing is provided. An oil-impregnated bearing mechanism in which a communication groove formed by a part and a part of the inner peripheral surface of the outer bearing is formed is described.

特許文献２に記載の含油軸受機構によれば、内側軸受の外周面と外側軸受の内周面との間に連通溝が形成され、内側軸受及び外側軸受から染み出した潤滑剤をこの連通溝において保持することができ、長寿命化された含油軸受機構が得られるとされている。 According to the oil-impregnated bearing mechanism described in Patent Document 2, a communication groove is formed between the outer peripheral surface of the inner bearing and the inner peripheral surface of the outer bearing, and the lubricant exuded from the inner bearing and the outer bearing is discharged from the communication groove. It is said that an oil-impregnated bearing mechanism that can be held in and has a long life can be obtained.

特開２００６−２９２１６１号公報Japanese Unexamined Patent Publication No. 2006-292161 特開２００９−８５３５５号公報JP-A-2009-85355

特許文献１や特許文献２に記載の二重構造の含油軸受では、アウター部（外側軸受）がインナー部（内側軸受）より低密度の場合には、インナー部をアウター部に圧入する際、インナー部の内径精度をそのまま維持できる可能性がある。
しかしながら、特許文献１や特許文献２に記載の二重構造の含油軸受を用いてモータを構成する際、二重構造の含油軸受をハウジング内に圧入すると、シャフトを直接支持するインナー部の内径精度を維持することが難しく、高精度な回転性能を実現することが難しいという問題がある。 In the double-structured oil-impregnated bearing described in Patent Document 1 and Patent Document 2, when the outer portion (outer bearing) has a lower density than the inner portion (inner bearing), the inner portion is press-fitted into the outer portion. There is a possibility that the inner diameter accuracy of the part can be maintained as it is.
However, when the motor is configured by using the double-structured oil-impregnated bearing described in Patent Document 1 and Patent Document 2, when the double-structured oil-impregnated bearing is press-fitted into the housing, the inner diameter accuracy of the inner portion that directly supports the shaft is accurate. There is a problem that it is difficult to maintain the bearing and it is difficult to realize high-precision rotation performance.

そこで、本発明の目的は、高精度な回転性能と長寿命化を実現できるブラシレスモータを提供しようとするものである。 Therefore, an object of the present invention is to provide a brushless motor capable of realizing highly accurate rotation performance and long life.

以下、上記の課題を解決するために為された本発明の態様を記載する。なお、以下に記載の各態様において採用される構成要素は、可能な限り任意な組み合わせで採用することができる。また、本発明の態様あるいは技術的特徴は以下に記載のものに限定されることなく、明細書全体および図面に記載されたもの、或いはそれらの記載から当業者が把握することの出来る発明思想に基づいて認識されるものである。 Hereinafter, aspects of the present invention made to solve the above problems will be described. The components adopted in each of the following aspects can be adopted in any combination as much as possible. Further, the aspects or technical features of the present invention are not limited to those described below, but are described in the entire specification and drawings, or invention ideas that can be grasped by those skilled in the art from those descriptions. It is recognized based on.

本発明の一実施態様は、
シャフトを有するロータと、オイルを媒介として前記シャフトの径方向を支持する筒状の軸受と、上端が開口し内部に前記軸受を支持する軸受ハウジングとを備えたブラシレスモータにおいて、
前記軸受は、多孔質含油材からなるインナー軸受と、該インナー軸受の外周面に装着された多孔質含油材からなるアウター軸受とを有し、
前記インナー軸受は、径方向内方に凸に形成された複数の軸受部を有し、
前記アウター軸受は、前記インナー軸受よりも含油率が大きく、
前記アウター軸受は、前記インナー軸受よりも軸方向に若干長く、かつ前記インナー軸受と前記アウター軸受の上端面は略面一となっており、
すべての前記軸受部の軸方向全体に亘って、前記軸受部と該軸受部の径方向外方に位置する前記軸受ハウジングとの間に間隙部が設けられている、
ことを特徴とする。 One embodiment of the present invention is
In a brushless motor including a rotor having a shaft, a tubular bearing that supports the shaft in the radial direction via oil, and a bearing housing that has an open upper end and supports the bearing inside.
The bearing has an inner bearing made of a porous oil-impregnated material and an outer bearing made of a porous oil-impregnated material mounted on the outer peripheral surface of the inner bearing.
The inner bearing has a plurality of bearing portions formed convex inward in the radial direction, and has a plurality of bearing portions.
The outer bearing has a higher oil content than the inner bearing.
The outer bearing, the slightly longer axially than the inner bearing, and an upper end surface of the said inner bearing outer bearing has a substantially flush,
A gap is provided between the bearing portion and the bearing housing located radially outward of the bearing portion over the entire axial direction of all the bearing portions.
It is characterized by that.

本発明の他の実施態様では、更なる特徴として、
「前記軸受部は、前記インナー軸受の上端部に設けられた上側軸受部と、前記インナー軸受の下端部に設けられた下側軸受部を有し、前記上側軸受部と該軸受部の径方向外方に位置する前記軸受ハウジングとの間に上部間隙部が設けられており、前記下側軸受部と該軸受部の径方向外方に位置する前記軸受ハウジングとの間に下部間隙部が設けられていること」、
「前記上側軸受部の軸方向全体に亘って、前記上側軸受部の径方向外方に位置する前記軸受ハウジングと前記アウター軸受との間に前記上部間隙部が設けられており、
前記下側軸受部の軸方向全体に亘って、前記下側軸受部と該下側軸受部の径方向外方に位置する前記アウター軸受との間に前記下部間隙部が設けられていること」、
「前記上側軸受部の軸方向全体に亘って、前記上側軸受部の径方向外方に位置する前記軸受ハウジングと前記アウター軸受との間に前記上部間隙部が設けられており、
前記下側軸受部の軸方向全体に亘って、前記下側軸受部の径方向外方に位置する前記軸受ハウジングと前記アウター軸受との間に前記下部間隙部が設けられていること」、

「前記インナー軸受の外周面と前記アウター軸受の内周面との間に、軸方向に連通する溝が設けられていること」、
「前記アウター軸受の外周面と前記軸受ハウジングの内周面との間に、軸方向に連通する溝が設けられていること」、
「前記シャフトの外表面には、前記インナー軸受から前記軸受ハウジングの開口側に突出した部分に環状溝が形成されていること」、
「前記軸受ハウジングの前記開口に環状の撥油部材が装着されており、前記撥油部材の下面は前記環状溝の上端よりも高い位置にあること」、
を含む。 In another embodiment of the invention, as a further feature,
"The bearing portion has an upper bearing portion provided at the upper end portion of the inner bearing and a lower bearing portion provided at the lower end portion of the inner bearing, and the upper bearing portion and the bearing portion in the radial direction. An upper gap is provided between the bearing housing located on the outside, and a lower gap is provided between the lower bearing and the bearing housing located radially outward of the bearing. What is being done ",
"The upper gap portion is provided between the bearing housing located radially outward of the upper bearing portion and the outer bearing over the entire axial direction of the upper bearing portion.
The lower gap portion is provided between the lower bearing portion and the outer bearing located radially outward of the lower bearing portion over the entire axial direction of the lower bearing portion. " ,
"The upper gap portion is provided between the bearing housing located radially outward of the upper bearing portion and the outer bearing over the entire axial direction of the upper bearing portion.
The lower gap portion is provided between the bearing housing located radially outward of the lower bearing portion and the outer bearing over the entire axial direction of the lower bearing portion. "

"A groove that communicates in the axial direction is provided between the outer peripheral surface of the inner bearing and the inner peripheral surface of the outer bearing."
"A groove that communicates in the axial direction is provided between the outer peripheral surface of the outer bearing and the inner peripheral surface of the bearing housing."
"On the outer surface of the shaft, an annular groove is formed in a portion protruding from the inner bearing toward the opening side of the bearing housing."
"An annular oil-repellent member is attached to the opening of the bearing housing, and the lower surface of the oil-repellent member is located higher than the upper end of the annular groove."
including.

本発明のブラシレスモータによれば、インナー軸受とアウター軸受からなる二重構造の軸受を用いて長寿命化を図りつつ、二重構造の軸受を軸受ハウジング内に支持固定させた際にインナー軸受の軸受部の内径精度を維持することができ、高精度な回転性能を得ることができる。 According to the brushless motor of the present invention, when a double-structured bearing composed of an inner bearing and an outer bearing is used to prolong the life of the double-structured bearing and the double-structured bearing is supported and fixed in the bearing housing, the inner bearing The inner diameter accuracy of the bearing portion can be maintained, and highly accurate rotational performance can be obtained.

本発明の第１の実施形態例に係るブラシレスモータの縦断面図である。It is a vertical sectional view of the brushless motor which concerns on 1st Embodiment of this invention. 本発明の第１の実施形態例に係るブラシレスモータの軸受ユニット（但し、撥油部材は省略）の上面図である。It is a top view of the bearing unit (however, the oil-repellent member is omitted) of the brushless motor which concerns on 1st Embodiment of this invention. 図２中のＡ−Ａ断面図である。FIG. 2 is a cross-sectional view taken along the line AA in FIG. 本発明の第２の実施形態例に係るブラシレスモータの軸受ユニット（但し、撥油部材は省略）の断面図である。It is sectional drawing of the bearing unit (however, the oil-repellent member is omitted) of the brushless motor which concerns on 2nd Embodiment of this invention. 本発明の第３の実施形態例に係るブラシレスモータの軸受ユニット（但し、撥油部材は省略）の断面図である。It is sectional drawing of the bearing unit (however, the oil-repellent member is omitted) of the brushless motor which concerns on 3rd Embodiment of this invention. 本発明の第４の実施形態例に係るブラシレスモータの軸受ユニット（但し、撥油部材は省略）の断面図である。It is sectional drawing of the bearing unit (however, the oil-repellent member is omitted) of the brushless motor which concerns on 4th Embodiment of this invention. 本発明の第５の実施形態例に係るブラシレスモータの軸受ユニット（但し、撥油部材は省略）の断面図である。It is sectional drawing of the bearing unit (however, the oil-repellent member is omitted) of the brushless motor which concerns on 5th Embodiment of this invention.

以下、本発明の実施形態例を、図面を参照して説明する。
なお、本明細書では、図１の上方向を「上側」と呼び、下方向を「下側」と呼ぶ。また、上下方向は、モータが実際の機器に組み込まれたときの位置関係や方向を示すものではない。また、シャフトの中心軸に平行な方向を「軸方向」と呼び、中心軸を中心とする半径方向を「径方向」と呼ぶ。 Hereinafter, examples of embodiments of the present invention will be described with reference to the drawings.
In the present specification, the upper direction of FIG. 1 is referred to as "upper side", and the lower direction is referred to as "lower side". Further, the vertical direction does not indicate the positional relationship or direction when the motor is incorporated in an actual device. Further, the direction parallel to the central axis of the shaft is referred to as "axial direction", and the radial direction centered on the central axis is referred to as "diameter direction".

（第１の実施形態例）
本発明の第１の実施形態例を、図１〜図３を用いて説明する。
本例のブラシレスモータは、主に、取付板１０と、ステータ２０と、ロータ３０と、軸受ユニット１４０で構成されている。 (Example of the first embodiment)
An example of the first embodiment of the present invention will be described with reference to FIGS. 1 to 3.
The brushless motor of this example is mainly composed of a mounting plate 10, a stator 20, a rotor 30, and a bearing unit 140.

取付板１０は、表面に印刷回路を形成したいわゆる鉄基板、あるいは鉄基板に印刷配線板を重ねた基板などが用いられ、中央部分には円筒状のバーリング部１１が下方を向くように形成されている。
この取付板１０には、後述の駆動用マグネット３３の下端と軸方向（図１の上下方向）で対向するようにホール素子（不図示）が設けられており、このホール素子によってロータ３０の回転を検出することができるようになっている。 As the mounting plate 10, a so-called iron substrate having a printed circuit formed on its surface, a substrate in which a printed wiring board is laminated on an iron substrate, or the like is used, and a cylindrical burring portion 11 is formed in a central portion so as to face downward. ing.
The mounting plate 10 is provided with a Hall element (not shown) so as to face the lower end of the drive magnet 33, which will be described later, in the axial direction (vertical direction in FIG. 1), and the Hall element rotates the rotor 30. Can be detected.

ステータ２０は、ステータコア２１、コアカバー２２及びコイル２３を備えている。
ステータコア２１は、中心に円形の開口を有し複数の突極が形成された板状コアの積層体からなり、その表面を絶縁性樹脂からなるコアカバー２２で被覆し、このコアカバー２２を介して各突極にコイル２３が巻かれている。 The stator 20 includes a stator core 21, a core cover 22, and a coil 23.
The stator core 21 is made of a laminated body of plate-shaped cores having a circular opening in the center and having a plurality of salient poles formed therein, and the surface thereof is covered with a core cover 22 made of an insulating resin, and the surface thereof is covered with a core cover 22 made of an insulating resin. A coil 23 is wound around each salient pole.

ロータ３０は、シャフト３１と、シャフト３１と一体に回転するロータケース３２と、ロータケース３２の内側に固定された駆動用マグネット３３を備えている。 The rotor 30 includes a shaft 31, a rotor case 32 that rotates integrally with the shaft 31, and a drive magnet 33 fixed inside the rotor case 32.

シャフト３１は、細長い略円柱状を成し、後述の軸受ユニット１４０によって回転自在に支持されている。
シャフト３１の下端近傍に位置する部分には被係止部３１ａが形成され、シャフト３１の中間よりやや上方に位置する部分には環状溝３１ｂが形成されている。この被係止部３１ａと環状溝３１ｂは、いずれもシャフト３１の外周に形成された環状の凹部で構成されている。 The shaft 31 has an elongated substantially cylindrical shape and is rotatably supported by a bearing unit 140 described later.
A locked portion 31a is formed in a portion located near the lower end of the shaft 31, and an annular groove 31b is formed in a portion located slightly above the middle of the shaft 31. Both the locked portion 31a and the annular groove 31b are formed of an annular recess formed on the outer periphery of the shaft 31.

ロータケース３２は、磁性を有する金属板から成り、シャフト３１と同軸で円筒状に形成された円筒部３２ａと、この円筒部３２ａの上面を覆う平板状の上面部３２ｂを有している。上面部３２ｂの中心には円筒状のバーリング部３２ｃが下方を向くように形成されており、このバーリング部３２ｃにシャフト３１の上部が圧入され固定されている。 The rotor case 32 is made of a magnetic metal plate and has a cylindrical portion 32a formed coaxially with the shaft 31 and a flat plate-shaped upper surface portion 32b that covers the upper surface of the cylindrical portion 32a. A cylindrical burring portion 32c is formed at the center of the upper surface portion 32b so as to face downward, and the upper portion of the shaft 31 is press-fitted and fixed to the burring portion 32c.

ロータケース３２の円筒部３２ａの内側には、ステータコア２１の突極と径方向（図１の左右方向）で対向するように円筒状の駆動用マグネット３３が取り付けられている。この駆動用マグネット３３は、周方向にＮ極とＳ極が交互に複数着磁されている。
また、バーリング部３２ｃの外周には、円筒状の吸引用マグネット３４が取り付けられている。 Inside the cylindrical portion 32a of the rotor case 32, a cylindrical driving magnet 33 is attached so as to face the salient pole of the stator core 21 in the radial direction (left-right direction in FIG. 1). The drive magnet 33 is magnetized with a plurality of N poles and S poles alternately in the circumferential direction.
A cylindrical suction magnet 34 is attached to the outer circumference of the burring portion 32c.

軸受ユニット１４０は、ロータ３０を回転自在に支持するものであり、インナー軸受１４１と、アウター軸受１４２と、軸受ハウジング１４３と、スラスト板１４４と、抜止め部材１４５と、撥油部材１４６を備えている。 The bearing unit 140 rotatably supports the rotor 30, and includes an inner bearing 141, an outer bearing 142, a bearing housing 143, a thrust plate 144, a retaining member 145, and an oil repellent member 146. There is.

インナー軸受１４１は、オイルを媒介としてシャフト３１の径方向を回転自在に支持するラジアル軸受である。アウター軸受１４２は、インナー軸受１４１の外周面に圧入等によって装着され、インナー軸受１４１への補油機構として機能するように設けられている。
インナー軸受１４１とアウター軸受１４２は、いずれも筒状の焼結メタル等にオイル（潤滑油）が含浸された多孔質含油材からなり、アウター軸受１４２はインナー軸受１４１よりも含油率の大きいものが用いられている。
一例を挙げると、インナー軸受１４１として密度が約５．５〜６．６ｇ／ｃｍ^３のものを用いた場合の含油率は約２２〜２６ｖｏｌ％となり、アウター軸受１４２として密度が約４．１〜４．９ｇ／ｃｍ^３のものを用いた場合の含油率は約３８〜４８ｖｏｌ％となる。 The inner bearing 141 is a radial bearing that rotatably supports the shaft 31 in the radial direction with oil as a medium. The outer bearing 142 is mounted on the outer peripheral surface of the inner bearing 141 by press fitting or the like, and is provided so as to function as a refueling mechanism for the inner bearing 141.
The inner bearing 141 and the outer bearing 142 are both made of a porous oil-impregnated material in which a tubular sintered metal or the like is impregnated with oil (lubricating oil), and the outer bearing 142 has a higher oil content than the inner bearing 141. It is used.
As an example, when an inner bearing 141 having a density of about 5.5 to 6.6 g / cm ³ is used, the oil content is about 22 to 26 vol%, and the outer bearing 142 has a density of about 4.1 to 1. When 4.9 g / cm ³ is used, the oil content is about 38 to 48 vol%.

インナー軸受１４１は、中心孔の上下両端にそれぞれ径方向内方に凸に形成された上部軸受部１４１ａと下部軸受部１４１ｂを有している。上部軸受部１４１ａと下部軸受部１４１ｂの間は、これらよりも内径の大きい中逃げ部１４１ｃとなっている。
上部軸受部１４１ａと下部軸受部１４１ｂの内径はシャフト３１の外径よりも僅かに大きく、上部軸受部１４１ａと下部軸受部１４１ｂによってシャフト３１の径方向を回転自在に支持することができる。また、中逃げ部１４１ｃを設けたことにより、シャフト３１との摺動抵抗を減少させてモータが過熱するのを抑制することができる。 The inner bearing 141 has an upper bearing portion 141a and a lower bearing portion 141b formed convexly inward in the radial direction at both upper and lower ends of the central hole, respectively. Between the upper bearing portion 141a and the lower bearing portion 141b, there is a middle relief portion 141c having a larger inner diameter than these.
The inner diameters of the upper bearing portion 141a and the lower bearing portion 141b are slightly larger than the outer diameter of the shaft 31, and the upper bearing portion 141a and the lower bearing portion 141b can rotatably support the radial direction of the shaft 31. Further, by providing the center relief portion 141c, it is possible to reduce the sliding resistance with the shaft 31 and suppress the motor from overheating.

インナー軸受１４１の外形は、上部軸受部１４１ａから中逃げ部１４１ｃの大半に亘る領域については外径が一定の大径部１４１ｄとなっており、中逃げ部１４１ｃの下端近傍から下部軸受部１４１ｂの領域については大径部１４１ｄよりも外径の小さい縮径部１４１ｅとなっている。
大径部１４１ｄの外周面には、軸方向に沿って複数本の溝１４１ｆが周方向に等間隔に形成されており、本例では８本の溝１４１ｆが形成されている。 The outer shape of the inner bearing 141 is a large diameter portion 141d having a constant outer diameter in the region extending from the upper bearing portion 141a to most of the middle relief portion 141c, and the lower bearing portion 141b is formed from the vicinity of the lower end of the middle relief portion 141c. The region is a reduced diameter portion 141e having an outer diameter smaller than that of the large diameter portion 141d.
On the outer peripheral surface of the large diameter portion 141d, a plurality of grooves 141f are formed at equal intervals in the circumferential direction along the axial direction, and in this example, eight grooves 141f are formed.

アウター軸受１４２は、インナー軸受１４１よりも軸方向に若干長く、アウター軸受１４２とインナー軸受１４１の上端面は面一であるが、アウター軸受１４２はインナー軸受１４１よりも若干下方に突出している。 The outer bearing 142 is slightly longer in the axial direction than the inner bearing 141, and the upper end surfaces of the outer bearing 142 and the inner bearing 141 are flush with each other, but the outer bearing 142 projects slightly downward from the inner bearing 141.

アウター軸受１４２の内径は軸方向の全体に亘って一定である。このアウター軸受１４２の内径は、インナー軸受１４１を内側に装着して固定できるように、インナー軸受１４１の大径部１４１ｄの外径よりも僅かに小さく設計されている。
アウター軸受１４２の外形は、インナー軸受１４１の上部軸受部１４１ａから中逃げ部１４１ｃの上端近傍までの径方向外方に位置する領域については、外径の小さい縮径部１４２ａとなっており、縮径部１４２ａよりも下の領域は縮径部１４２ａより外径の大きい大径部１４２ｂとなっている。
アウター軸受１４２の大径部１４２ｂの外周面には、軸方向に沿って複数本の溝１４２ｃが周方向に等間隔に形成されており、本例では１２本の溝１４２ｃが形成されている。 The inner diameter of the outer bearing 142 is constant over the entire axial direction. The inner diameter of the outer bearing 142 is designed to be slightly smaller than the outer diameter of the large diameter portion 141d of the inner bearing 141 so that the inner bearing 141 can be mounted and fixed inside.
The outer shape of the outer bearing 142 is a reduced diameter portion 142a having a small outer diameter in the region located radially outward from the upper bearing portion 141a of the inner bearing 141 to the vicinity of the upper end of the middle relief portion 141c. The region below the diameter portion 142a is a large diameter portion 142b having a larger outer diameter than the reduced diameter portion 142a.
On the outer peripheral surface of the large diameter portion 142b of the outer bearing 142, a plurality of grooves 142c are formed at equal intervals in the circumferential direction along the axial direction, and in this example, 12 grooves 142c are formed.

軸受ハウジング１４３は、インナー軸受１４１とアウター軸受１４２を内部に保持して固定するものであり、筒部と底部を有し上端が開口した有底筒状を成し、筒部１４３ａの上端には径方向外方に突出した鍔１４３ａ１が形成されている。
この軸受ハウジング１４３は、金属材料の深絞り品や切削品などを用いることができ、本例では深絞り品を用いている。 The bearing housing 143 holds and fixes the inner bearing 141 and the outer bearing 142 inside, and has a bottomed tubular shape having a tubular portion and a bottom portion and an open upper end, and the upper end portion of the tubular portion 143a has a bottomed tubular shape. A bearing 143a1 protruding outward in the radial direction is formed.
As the bearing housing 143, a deep-drawn product or a cut product made of a metal material can be used, and in this example, a deep-drawn product is used.

軸受ハウジング１４３の筒部１４３ａの内径は概ね一定である。この筒部１４３ａの内径は、アウター軸受１４２を内側に装着して固定できるように、アウター軸受１４２の大径部１４２ｂの外径よりも僅かに小さく設計されている。
軸受ハウジング１４３の底部は２段底の構造を成しており、第１底部１４３ｂと、第１底部１４３ｂの中央部が凹んだ第２底部１４３ｃを有している。 The inner diameter of the tubular portion 143a of the bearing housing 143 is substantially constant. The inner diameter of the tubular portion 143a is designed to be slightly smaller than the outer diameter of the large diameter portion 142b of the outer bearing 142 so that the outer bearing 142 can be mounted and fixed inside.
The bottom portion of the bearing housing 143 has a two-stage bottom structure, and has a first bottom portion 143b and a second bottom portion 143c in which the central portion of the first bottom portion 143b is recessed.

軸受ハウジング１４３は、取付板１０のバーリング部１１に圧入等によって固定されている。ステータコア２１は、軸受ハウジング１４３の外周上部に嵌め込まれ、鍔１４３ａ１の下面に当接された状態で固定されている。 The bearing housing 143 is fixed to the burring portion 11 of the mounting plate 10 by press fitting or the like. The stator core 21 is fitted in the upper part of the outer circumference of the bearing housing 143 and is fixed in contact with the lower surface of the collar 143a1.

スラスト板１４４は、耐摩耗性の樹脂板等からなり、軸受ハウジング１４３の第２底部１４３ｃの上に配されてシャフト３１の下端を支持する。 The thrust plate 144 is made of a wear-resistant resin plate or the like, and is arranged on the second bottom portion 143c of the bearing housing 143 to support the lower end of the shaft 31.

抜止め部材１４５は、リング状のワッシャからなり、軸受ハウジング１４３の第１底部１４３ｂの上に配されている。この抜止め部材１４５は、外縁部がアウター軸受１４２と第１底部１４３ｂに挟まれ固定されている。
抜止め部材１４５の内径部は、シャフト３１の被係止部３１ａに挿入されている。これにより、シャフト３１は上方への移動を制限され、ロータ３０が軸受ユニット１４０から抜けるのを防止することができる。 The retaining member 145 is composed of a ring-shaped washer and is arranged on the first bottom portion 143b of the bearing housing 143. The outer edge portion of the retaining member 145 is sandwiched between the outer bearing 142 and the first bottom portion 143b and fixed.
The inner diameter portion of the retaining member 145 is inserted into the locked portion 31a of the shaft 31. As a result, the shaft 31 is restricted from moving upward, and the rotor 30 can be prevented from coming off the bearing unit 140.

撥油部材１４６は、中央に貫通口を有し、表面が撥油処理された円環状の金属板からなり、軸受ハウジング１４３の開口部の上端に圧入されている。撥油部材１４６の貫通口の直径はシャフト３１の外径よりも僅かに大きく、シャフト３１と撥油部材１４６との間に僅かな隙間が設けられている。
撥油部材１４６の下面とインナー軸受１４１及びアウター軸受１４２の上面との間には空間Ｓが形成され、シャフト３１の環状溝３１ｂは空間Ｓに位置している。
なお、本例では撥油部材１４６として磁性金属材料を用いており、この撥油部材１４６と対向配置される吸引用マグネット３４との間に作用する磁気吸引力によって、ロータ３０が回転中に浮上するのを防止している。 The oil-repellent member 146 has a through hole in the center, is made of an annular metal plate whose surface is oil-repellent treated, and is press-fitted into the upper end of the opening of the bearing housing 143. The diameter of the through hole of the oil-repellent member 146 is slightly larger than the outer diameter of the shaft 31, and a slight gap is provided between the shaft 31 and the oil-repellent member 146.
A space S is formed between the lower surface of the oil repellent member 146 and the upper surface of the inner bearing 141 and the outer bearing 142, and the annular groove 31b of the shaft 31 is located in the space S.
In this example, a magnetic metal material is used as the oil-repellent member 146, and the rotor 30 floats during rotation due to the magnetic attraction force acting between the oil-repellent member 146 and the suction magnet 34 arranged to face each other. It is prevented from doing.

以上説明した本例のブラシレスモータでは、インナー軸受１４１とこれよりも含油率が大きいアウター軸受１４２からなる二重構造の軸受を用いたことにより、アウター軸受１４２からインナー軸受１４１へ逐次補油されるため、モータの長寿命化を図ることができる。 In the brushless motor of this example described above, by using a double-structured bearing composed of an inner bearing 141 and an outer bearing 142 having a higher oil content than this, oil is sequentially replenished from the outer bearing 142 to the inner bearing 141. Therefore, the life of the motor can be extended.

また本例のブラシレスモータでは、軸受ハウジング１４３の筒部１４３ａの内径は一定であるものの、アウター軸受１４２の所定領域に外径の小さい縮径部１４２ａを設けている。これにより、上側軸受部１４１ａの軸方向全体に亘って、上側軸受部１４１ａの径方向外方に位置する軸受ハウジング１４３とアウター軸受１４２との間に上部間隙部１４７が形成されている。
さらに本例のブラシレスモータでは、アウター軸受１４２の内径は軸方向の全体に亘って一定であるものの、インナー軸受１４１の所定領域に外径の小さい縮径部１４１ｅを設けている。これにより、下側軸受部１４１ｂの軸方向全体に亘って、下側軸受部１４１ｂと該下側軸受部１４１ｂの径方向外方に位置するアウター軸受１４２との間に下部間隙部１４８が形成されている。
このように、本例のブラシレスモータでは、インナー軸受１４１のすべての軸受部（上部軸受部１４１ａと下部軸受部１４１ｂ）の軸方向全体に亘って、軸受部と軸受ハウジング１４３との間に全周に亘って間隙部（上部間隙部１４７と下部間隙部１４８）が設けられている。
このような構成によれば、インナー軸受１４１とアウター軸受１４２からなる二重構造の軸受を軸受ハウジング１４３内に圧入した際に、シャフト３１を直接支持するインナー軸受１４１の上部軸受部１４１ａと下部軸受部１４１ｂに径方向の大きな圧縮力が掛かるのを効果的に抑制できる。このため、上部軸受部１４１ａと下部軸受部１４１ｂの内径が収縮するのを抑制して、軸受部の内径精度を維持することができ、高精度な回転性能を得ることができる。 Further, in the brushless motor of this example, although the inner diameter of the tubular portion 143a of the bearing housing 143 is constant, a reduced diameter portion 142a having a small outer diameter is provided in a predetermined region of the outer bearing 142. As a result, an upper gap portion 147 is formed between the bearing housing 143 located radially outward of the upper bearing portion 141a and the outer bearing 142 over the entire axial direction of the upper bearing portion 141a.
Further, in the brushless motor of this example, although the inner diameter of the outer bearing 142 is constant over the entire axial direction, a reduced diameter portion 141e having a small outer diameter is provided in a predetermined region of the inner bearing 141. As a result, a lower gap portion 148 is formed between the lower bearing portion 141b and the outer bearing 142 located radially outward of the lower bearing portion 141b over the entire axial direction of the lower bearing portion 141b. ing.
As described above, in the brushless motor of this example, the entire circumference between the bearing portion and the bearing housing 143 over the entire axial direction of all the bearing portions (upper bearing portion 141a and lower bearing portion 141b) of the inner bearing 141. A gap portion (upper gap portion 147 and lower gap portion 148) is provided.
According to such a configuration, when a double-structured bearing composed of an inner bearing 141 and an outer bearing 142 is press-fitted into the bearing housing 143, the upper bearing portion 141a and the lower bearing of the inner bearing 141 that directly supports the shaft 31 are formed. It is possible to effectively suppress the application of a large radial compressive force to the portion 141b. Therefore, it is possible to suppress the shrinkage of the inner diameters of the upper bearing portion 141a and the lower bearing portion 141b, maintain the inner diameter accuracy of the bearing portion, and obtain highly accurate rotational performance.

また、本例のブラシレスモータでは、インナー軸受１４１の外周面とアウター軸受１４２の内周面との間に、軸方向に連通する溝１４１ｆを設けている。
このような構成によれば、インナー軸受１４１からその外周面に染み出したオイルと、アウター軸受１４２からその内周面に染み出したオイルを溝１４１ｆに保持することができ、モータのさらなる長寿命化を図ることができる。 Further, in the brushless motor of this example, a groove 141f communicating in the axial direction is provided between the outer peripheral surface of the inner bearing 141 and the inner peripheral surface of the outer bearing 142.
According to such a configuration, the oil exuded from the inner bearing 141 to the outer peripheral surface thereof and the oil exuded from the outer bearing 142 to the inner peripheral surface thereof can be held in the groove 141f, and the life of the motor is further extended. Can be achieved.

また、本例のブラシレスモータでは、アウター軸受１４２の外周面と軸受ハウジング１４３の内周面との間に、軸方向に連通する溝１４２ｃを設けている。
このような構成によれば、モータ駆動時の熱によってオイルが膨張した際、溝１４２ｃにオイルを保持でき、軸受外部へのオイル漏れを抑制することができる。 Further, in the brushless motor of this example, a groove 142c communicating in the axial direction is provided between the outer peripheral surface of the outer bearing 142 and the inner peripheral surface of the bearing housing 143.
According to such a configuration, when the oil expands due to the heat generated when the motor is driven, the oil can be retained in the groove 142c and the oil leakage to the outside of the bearing can be suppressed.

また、本例のブラシレスモータでは、シャフト３１の外表面には、インナー軸受１４１から軸受ハウジング１４３の開口側に突出した部分に環状溝３１ｂが形成されている。
このような構成によれば、シャフト３１の回転によってインナー軸受１４１の内周面に滲み出したオイルは、インナー軸受１４１の上端面を超えて環状溝３１ｂにある程度溜まると、シャフト３１の回転に伴う遠心力によって径方向外方に飛ばされるため、オイルをインナー軸受１４１とアウター軸受１４２に効果的に戻すことができる。 Further, in the brushless motor of this example, an annular groove 31b is formed on the outer surface of the shaft 31 at a portion protruding from the inner bearing 141 toward the opening side of the bearing housing 143.
According to such a configuration, when the oil exuded to the inner peripheral surface of the inner bearing 141 due to the rotation of the shaft 31 exceeds the upper end surface of the inner bearing 141 and accumulates to some extent in the annular groove 31b, it accompanies the rotation of the shaft 31. Since the oil is blown outward in the radial direction by the centrifugal force, the oil can be effectively returned to the inner bearing 141 and the outer bearing 142.

また、本例のブラシレスモータでは、軸受ハウジング１４３の開口部に環状の撥油部材１４６が装着されており、撥油部材１４６の下面は環状溝３１ｂの上端よりも高い位置にある。具体的には、撥油部材１４６の下面とインナー軸受１４１及びアウター軸受１４２の上面との間には空間Ｓが形成され、シャフト３１の環状溝３１ｂはこの空間Ｓに面している。
このような撥油部材１４６を設けることにより、特にモータを水平状態やこれに近い状態で用いる場合において、シャフト３１の回転に伴う遠心力によって径方向外方に飛ばされるオイルの量が多い場合であっても、軸受ユニット外部へのオイルの飛散を極めて効果的に抑制し、さらなるモータの長寿命化を図ることができる。 Further, in the brushless motor of this example, an annular oil-repellent member 146 is mounted on the opening of the bearing housing 143, and the lower surface of the oil-repellent member 146 is located higher than the upper end of the annular groove 31b. Specifically, a space S is formed between the lower surface of the oil-repellent member 146 and the upper surface of the inner bearing 141 and the outer bearing 142, and the annular groove 31b of the shaft 31 faces the space S.
By providing such an oil-repellent member 146, especially when the motor is used in a horizontal state or a state close to this, when the amount of oil blown outward in the radial direction by the centrifugal force accompanying the rotation of the shaft 31 is large. Even if there is, it is possible to extremely effectively suppress the scattering of oil to the outside of the bearing unit and further extend the life of the motor.

（第２の実施形態例）
本発明の第２の実施形態例に係るブラシレスモータは、軸受ユニットの構造だけが第１の実施形態例と異なる。
本例の軸受ユニット２４０を図４に示す。図４において、図１〜図３中の部材と同等の部材には同一の符号を付しており、重複する部分については説明を省略する。 (Example of the second embodiment)
The brushless motor according to the second embodiment of the present invention differs from the first embodiment only in the structure of the bearing unit.
The bearing unit 240 of this example is shown in FIG. In FIG. 4, members equivalent to the members in FIGS. 1 to 3 are designated by the same reference numerals, and the description of overlapping portions will be omitted.

本例のインナー軸受２４１は、先のインナー軸受１４１と同様、上部軸受部２４１ａと下部軸受部２４１ｂと中逃げ部２４１ｃを有している。
インナー軸受２４１の外形は、下部軸受部２４１ｂから中逃げ部２４１ｃの大半に亘る領域については外径が一定の大径部２４１ｄとなっており、中逃げ部２４１ｃの上端近傍から上部軸受部２４１ａの領域については大径部２４１ｄよりも外径の小さい縮径部２４１ｅとなっている。
大径部２４１ｄの外周面には、軸方向に沿って複数本の溝２４１ｆが周方向に等間隔に形成されている。 The inner bearing 241 of this example has an upper bearing portion 241a, a lower bearing portion 241b, and a middle relief portion 241c, similarly to the inner bearing 141 described above.
The outer shape of the inner bearing 241 is a large diameter portion 241d having a constant outer diameter in the region extending from the lower bearing portion 241b to most of the middle relief portion 241c. The region is a reduced diameter portion 241e having an outer diameter smaller than that of the large diameter portion 241d.
On the outer peripheral surface of the large diameter portion 241d, a plurality of grooves 241f are formed at equal intervals in the circumferential direction along the axial direction.

本例のアウター軸受２４２の内径は軸方向の全体に亘って一定である。このアウター軸受２４２の外形は、インナー軸受２４１の上部軸受部２４１ａから中逃げ部２４１ｃの下端近傍までの径方向外方に位置する領域については、外径の大きい大径部２４２ｂとなっており、大径部２４２ｂよりも下の領域は大径部２４２ｂよりも外径の小さい縮径部２４２ａとなっている。
アウター軸受２４２の大径部２４２ｂの外周面には、軸方向に沿って複数本の溝２４２ｃが周方向に等間隔に形成されている。 The inner diameter of the outer bearing 242 of this example is constant over the entire axial direction. The outer shape of the outer bearing 242 is a large diameter portion 242b having a large outer diameter in a region located radially outward from the upper bearing portion 241a of the inner bearing 241 to the vicinity of the lower end of the middle relief portion 241c. The region below the large diameter portion 242b is a reduced diameter portion 242a having a smaller outer diameter than the large diameter portion 242b.
On the outer peripheral surface of the large-diameter portion 242b of the outer bearing 242, a plurality of grooves 242c are formed at equal intervals in the circumferential direction along the axial direction.

以上の軸受ユニット２４０を用いた本例のブラシレスモータでは、アウター軸受２４２の内径は軸方向の全体に亘って一定であるものの、インナー軸受２４１の所定領域に外径の小さい縮径部２４１ｅを設けている。これにより、上側軸受部２４１ａの軸方向全体に亘って、上側軸受部２４１ａと該上側軸受部２４１ａの径方向外方に位置するアウター軸受２４２との間に上部間隙部２４７が形成されている。
また、本例のブラシレスモータでは、軸受ハウジング１４３の筒部１４３ａの内径は一定であるものの、アウター軸受２４２の所定領域に外径の小さい縮径部２４２ａを設けている。これにより、下側軸受部２４１ｂの軸方向全体に亘って、下側軸受部２４１ｂの径方向外方に位置する軸受ハウジング１４３とアウター軸受２４２との間に下部間隙部２４８が形成されている。
このように、本例のブラシレスモータでは、インナー軸受２４１のすべての軸受部（上部軸受部２４１ａと下部軸受部２４１ｂ）の軸方向全体に亘って、軸受部と軸受ハウジング１４３との間に全周に亘って間隙部（上部間隙部２４７と下部間隙部２４８）が設けられている。
このような構成によれば、インナー軸受２４１とアウター軸受２４２からなる二重構造の軸受を軸受ハウジング１４３内に圧入した際に、インナー軸受２４１の上部軸受部２４１ａと下部軸受部２４１ｂに径方向の大きな圧縮力が掛かるのを効果的に抑制できる。このため、上部軸受部２４１ａと下部軸受部２４１ｂの内径が収縮するのを抑制して、軸受部の内径精度を維持することができ、高精度な回転性能を得ることができる。 In the brushless motor of this example using the above bearing unit 240, although the inner diameter of the outer bearing 242 is constant over the entire axial direction, a reduced diameter portion 241e having a small outer diameter is provided in a predetermined region of the inner bearing 241. ing. As a result, an upper gap portion 247 is formed between the upper bearing portion 241a and the outer bearing 242 located radially outward of the upper bearing portion 241a over the entire axial direction of the upper bearing portion 241a.
Further, in the brushless motor of this example, although the inner diameter of the tubular portion 143a of the bearing housing 143 is constant, a reduced diameter portion 242a having a small outer diameter is provided in a predetermined region of the outer bearing 242. As a result, a lower gap portion 248 is formed between the bearing housing 143 and the outer bearing 242 located on the outer side in the radial direction of the lower bearing portion 241b over the entire axial direction of the lower bearing portion 241b.
As described above, in the brushless motor of this example, the entire circumference between the bearing portion and the bearing housing 143 over the entire axial direction of all the bearing portions (upper bearing portion 241a and lower bearing portion 241b) of the inner bearing 241. Gap portions (upper gap portion 247 and lower gap portion 248) are provided.
According to such a configuration, when a double-structured bearing composed of an inner bearing 241 and an outer bearing 242 is press-fitted into the bearing housing 143, the upper bearing portion 241a and the lower bearing portion 241b of the inner bearing 241 are radially aligned. It is possible to effectively suppress the application of a large compressive force. Therefore, it is possible to suppress the shrinkage of the inner diameters of the upper bearing portion 241a and the lower bearing portion 241b, maintain the inner diameter accuracy of the bearing portion, and obtain highly accurate rotational performance.

また、本例のブラシレスモータでは、アウター軸受２４２の下側領域に外径の小さい縮径部２４２ａを設けているため、二重構造の軸受を軸受ハウジング内に圧入するのが容易になり、モータ組立時の作業性を高めることができる。 Further, in the brushless motor of this example, since the reduced diameter portion 242a having a small outer diameter is provided in the lower region of the outer bearing 242, it becomes easy to press-fit the double-structured bearing into the bearing housing, and the motor. Workability during assembly can be improved.

（第３の実施形態例）
本発明の第３の実施形態例に係るブラシレスモータは、軸受ユニットの構造だけが第１の実施形態例と異なる。
本例の軸受ユニット３４０を図５に示す。図５において、図１〜図３中の部材と同等の部材には同一の符号を付しており、重複する部分については説明を省略する。 (Example of Third Embodiment)
The brushless motor according to the third embodiment of the present invention differs from the first embodiment only in the structure of the bearing unit.
The bearing unit 340 of this example is shown in FIG. In FIG. 5, members equivalent to the members in FIGS. 1 to 3 are designated by the same reference numerals, and the description of overlapping portions will be omitted.

本例のインナー軸受３４１は、先のインナー軸受１４１と同様、上部軸受部３４１ａと下部軸受部３４１ｂと中逃げ部３４１ｃを有している。このインナー軸受３４１の外径は、軸方向の全体に亘って一定である。
また、インナー軸受３４１の外周面には、軸方向に沿って複数本の溝３４１ｆが周方向に等間隔に形成されている。 The inner bearing 341 of this example has an upper bearing portion 341a, a lower bearing portion 341b, and a middle relief portion 341c, similarly to the inner bearing 141 described above. The outer diameter of the inner bearing 341 is constant over the entire axial direction.
Further, on the outer peripheral surface of the inner bearing 341, a plurality of grooves 341f are formed at equal intervals in the circumferential direction along the axial direction.

本例のアウター軸受２４２の内径は軸方向の全体に亘って一定である。このアウター軸受２４２の外形は、インナー軸受２４１の中逃げ部２４１ｃの上端近傍から下端近傍までの径方向外方に位置する領域については、外径の大きい大径部３４２ｂとなっており、それ以外の領域は大径部３４２ｂよりも外径の小さい縮径部３４２ａとなっている。
アウター軸受３４２の大径部３４２ｂの外周面には、軸方向に沿って複数本の溝３４２ｃが周方向に等間隔に形成されている。 The inner diameter of the outer bearing 242 of this example is constant over the entire axial direction. The outer shape of the outer bearing 242 is a large diameter portion 342b having a large outer diameter in the region located radially outward from the vicinity of the upper end to the vicinity of the lower end of the inner relief portion 241c of the inner bearing 241. The region of is a reduced diameter portion 342a having a smaller outer diameter than the large diameter portion 342b.
On the outer peripheral surface of the large-diameter portion 342b of the outer bearing 342, a plurality of grooves 342c are formed at equal intervals in the circumferential direction along the axial direction.

以上の軸受ユニット３４０を用いた本例のブラシレスモータでは、軸受ハウジング１４３の筒部１４３ａの内径は一定であるものの、アウター軸受３４２の所定領域に外径の小さい縮径部３４２ａを設けている。これにより、インナー軸受３４１のすべての軸受部（上部軸受部３４１ａと下部軸受部３４１ｂ）の軸方向全体に亘って、軸受部と軸受ハウジング１４３との間に全周に亘って間隙部（上部間隙部３４７と下部間隙部３４８）が設けられている。
このような構成によれば、インナー軸受３４１とアウター軸受３４２からなる二重構造の軸受を軸受ハウジング１４３内に圧入した際に、インナー軸受３４１の上部軸受部３４１ａと下部軸受部３４１ｂに径方向の大きな圧縮力が掛かるのを効果的に抑制できる。このため、上部軸受部３４１ａと下部軸受部３４１ｂの内径が収縮するのを抑制して、軸受部の内径精度を維持することができ、高精度な回転性能を得ることができる。 In the brushless motor of this example using the bearing unit 340 described above, although the inner diameter of the tubular portion 143a of the bearing housing 143 is constant, a reduced diameter portion 342a having a small outer diameter is provided in a predetermined region of the outer bearing 342. As a result, there is a gap (upper gap) over the entire axial direction between all the bearings (upper bearing 341a and lower bearing 341b) of the inner bearing 341 and between the bearing and the bearing housing 143. A portion 347 and a lower gap portion 348) are provided.
According to such a configuration, when a double-structured bearing composed of an inner bearing 341 and an outer bearing 342 is press-fitted into the bearing housing 143, the upper bearing portion 341a and the lower bearing portion 341b of the inner bearing 341 are radially aligned. It is possible to effectively suppress the application of a large compressive force. Therefore, it is possible to suppress the shrinkage of the inner diameters of the upper bearing portion 341a and the lower bearing portion 341b, maintain the inner diameter accuracy of the bearing portion, and obtain highly accurate rotational performance.

また、本例のブラシレスモータにおいても、アウター軸受３４２の下側領域に外径の小さい縮径部３４２ａを設けているため、二重構造の軸受を軸受ハウジング内に圧入するのが容易になり、モータ組立時の作業性を高めることができる。 Further, also in the brushless motor of this example, since the reduced diameter portion 342a having a small outer diameter is provided in the lower region of the outer bearing 342, it becomes easy to press-fit the double-structured bearing into the bearing housing. Workability during motor assembly can be improved.

（第４の実施形態例）
本発明の第４の実施形態例に係るブラシレスモータは、軸受ユニットの構造だけが第１の実施形態例と異なる。
本例の軸受ユニット４４０を図６に示す。図６において、図１〜図３中の部材と同等の部材には同一の符号を付しており、重複する部分については説明を省略する。 (Example of Fourth Embodiment)
The brushless motor according to the fourth embodiment of the present invention differs from the first embodiment only in the structure of the bearing unit.
The bearing unit 440 of this example is shown in FIG. In FIG. 6, members equivalent to the members in FIGS. 1 to 3 are designated by the same reference numerals, and the description of overlapping portions will be omitted.

本例のインナー軸受４４１は、先のインナー軸受１４１と同様、上部軸受部４４１ａと下部軸受部４４１ｂと中逃げ部４４１ｃを有している。
インナー軸受４４１の外形は、上部軸受部４４１ａから中逃げ部４４１ｃの大半に亘る領域については外径が一定の大径部４４１ｄとなっており、中逃げ部４４１ｃの下端近傍から下部軸受部４４１ｂの領域については大径部４４１ｄよりも外径の小さい縮径部４４１ｅとなっている。
大径部４４１ｄの外周面には、軸方向に沿って複数本の溝４４１ｆが周方向に等間隔に形成されている。 The inner bearing 441 of this example has an upper bearing portion 441a, a lower bearing portion 441b, and a middle relief portion 441c, similarly to the inner bearing 141 described above.
The outer shape of the inner bearing 441 is a large diameter portion 441d having a constant outer diameter in the region extending from the upper bearing portion 441a to most of the middle relief portion 441c, and the lower bearing portion 441b from the vicinity of the lower end of the middle relief portion 441c. The region is a reduced diameter portion 441e having an outer diameter smaller than that of the large diameter portion 441d.
On the outer peripheral surface of the large diameter portion 441d, a plurality of grooves 441f are formed at equal intervals in the circumferential direction along the axial direction.

本例のアウター軸受４４２の内径と外径は軸方向の全体に亘って一定である。このアウター軸受４４２の外周面には、軸方向に沿って複数本の溝４４２ｃが周方向に等間隔に形成されている。 The inner and outer diameters of the outer bearing 442 of this example are constant over the entire axial direction. On the outer peripheral surface of the outer bearing 442, a plurality of grooves 442c are formed at equal intervals in the circumferential direction along the axial direction.

本例の軸受ハウジング４４３では、筒部１４３ａの中ほどに段差部４４３ｄが設けられ、段差部４４３ｄよりも上方は内径の大きい大径部４４３ｅとなっており、段差部４４３ｄよりも下方は内径の小さい小径部４４３ｆとなっている。 In the bearing housing 443 of this example, a step portion 443d is provided in the middle of the tubular portion 143a, a large diameter portion 443e having a large inner diameter above the step portion 443d, and an inner diameter below the step portion 443d. It is a small diameter portion 443f.

以上の軸受ユニット４４０を用いた本例のブラシレスモータでは、アウター軸受４４２の外径は軸方向の全体に亘って一定であるものの、軸受ハウジング４４３の所定領域に外径の大きい大径部４４３ｅを設けている。これにより、上側軸受部４４１ａの軸方向全体に亘って、上側軸受部４４１ａと該上側軸受部４４１ａの径方向外方に位置する軸受ハウジング４４３との間に上部間隙部４４７が形成されている。
また、本例のブラシレスモータでは、アウター軸受４４２の内径は軸方向の全体に亘って一定であるものの、インナー軸受４４１の所定領域に外径の小さい縮径部４４１ｅを設けている。これにより、下側軸受部４４１ｂの軸方向全体に亘って、下側軸受部４４１ｂと該下側軸受部４４１ｂの径方向外方に位置するアウター軸受４４２との間に下部間隙部４４８が形成されている。
このように、本例のブラシレスモータでは、インナー軸受４４１のすべての軸受部（上部軸受部４４１ａと下部軸受部４４１ｂ）の軸方向全体に亘って、軸受部と軸受ハウジング４４３との間に全周に亘って間隙部（上部間隙部４４７と下部間隙部４４８）が設けられている。
このような構成によれば、インナー軸受４４１とアウター軸受４４２からなる二重構造の軸受を軸受ハウジング４４３内に圧入した際に、インナー軸受４４１の上部軸受部４４１ａと下部軸受部４４１ｂに径方向の大きな圧縮力が掛かるのを効果的に抑制できる。このため、上部軸受部４４１ａと下部軸受部４４１ｂの内径が収縮するのを抑制して、軸受部の内径精度を維持することができ、高精度な回転性能を得ることができる。 In the brushless motor of this example using the above bearing unit 440, although the outer diameter of the outer bearing 442 is constant over the entire axial direction, a large diameter portion 443e having a large outer diameter is provided in a predetermined region of the bearing housing 443. It is provided. As a result, an upper gap portion 447 is formed between the upper bearing portion 441a and the bearing housing 443 located radially outward of the upper bearing portion 441a over the entire axial direction of the upper bearing portion 441a.
Further, in the brushless motor of this example, although the inner diameter of the outer bearing 442 is constant over the entire axial direction, a reduced diameter portion 441e having a small outer diameter is provided in a predetermined region of the inner bearing 441. As a result, a lower gap portion 448 is formed between the lower bearing portion 441b and the outer bearing 442 located radially outward of the lower bearing portion 441b over the entire axial direction of the lower bearing portion 441b. ing.
As described above, in the brushless motor of this example, the entire circumference between the bearing portion and the bearing housing 443 over the entire axial direction of all the bearing portions (upper bearing portion 441a and lower bearing portion 441b) of the inner bearing 441. A gap portion (upper gap portion 447 and lower gap portion 448) is provided.
According to such a configuration, when a double-structured bearing composed of an inner bearing 441 and an outer bearing 442 is press-fitted into the bearing housing 443, it is radially connected to the upper bearing portion 441a and the lower bearing portion 441b of the inner bearing 441. It is possible to effectively suppress the application of a large compressive force. Therefore, it is possible to suppress the shrinkage of the inner diameters of the upper bearing portion 441a and the lower bearing portion 441b, maintain the inner diameter accuracy of the bearing portion, and obtain highly accurate rotational performance.

（第５の実施形態例）
本発明の第５の実施形態例に係るブラシレスモータは、軸受ユニットの構造だけが第１の実施形態例と異なる。
本例の軸受ユニット５４０を図７に示す。図７において、図１〜図３中の部材と同等の部材には同一の符号を付しており、重複する部分については説明を省略する。 (Example of Fifth Embodiment)
The brushless motor according to the fifth embodiment of the present invention differs from the first embodiment only in the structure of the bearing unit.
The bearing unit 540 of this example is shown in FIG. In FIG. 7, members equivalent to the members in FIGS. 1 to 3 are designated by the same reference numerals, and the description of overlapping portions will be omitted.

本例のインナー軸受５４１は、先のインナー軸受１４１と同様、上部軸受部５４１ａと下部軸受部５４１ｂと中逃げ部５４１ｃを有している。このインナー軸受５４１の外径は、軸方向の全体に亘って一定である。
また、インナー軸受５４１の外周面には、軸方向に沿って複数本の溝５４１ｆが周方向に等間隔に形成されている。 The inner bearing 541 of this example has an upper bearing portion 541a, a lower bearing portion 541b, and a middle relief portion 541c, similarly to the inner bearing 141 described above. The outer diameter of the inner bearing 541 is constant over the entire axial direction.
Further, on the outer peripheral surface of the inner bearing 541, a plurality of grooves 541f are formed at equal intervals in the circumferential direction along the axial direction.

本例のアウター軸受５４２の内径は軸方向の全体に亘って一定である。このアウター軸受５４２の外形は、インナー軸受５４１の上部軸受部５４１ａから中逃げ部５４１ｃの下端近傍までの径方向外方に位置する領域については、外径の大きい大径部５４２ｂとなっており、大径部５４２ｂよりも下の領域は大径部５４２ｂよりも外径の小さい縮径部５４２ａとなっている。
アウター軸受５４２の大径部５４２ｂの外周面には、軸方向に沿って複数本の溝５４２ｃが周方向に等間隔に形成されている。 The inner diameter of the outer bearing 542 of this example is constant over the entire axial direction. The outer shape of the outer bearing 542 is a large diameter portion 542b having a large outer diameter in a region located radially outward from the upper bearing portion 541a of the inner bearing 541 to the vicinity of the lower end of the middle relief portion 541c. The region below the large diameter portion 542b is a reduced diameter portion 542a having a smaller outer diameter than the large diameter portion 542b.
On the outer peripheral surface of the large-diameter portion 542b of the outer bearing 542, a plurality of grooves 542c are formed at equal intervals in the circumferential direction along the axial direction.

本例の軸受ハウジング４４３は、筒部１４３ａの中ほどに段差部４４３ｄが設けられ、段差部４４３ｄよりも上方は内径の大きい大径部４４３ｅとなっており、段差部４４３ｄよりも下方は内径の小さい小径部４４３ｆとなっている。 In the bearing housing 443 of this example, a step portion 443d is provided in the middle of the tubular portion 143a, a large diameter portion 443e having a large inner diameter above the step portion 443d, and an inner diameter below the step portion 443d. It is a small diameter portion 443f.

以上の軸受ユニット５４０を用いた本例のブラシレスモータでは、軸受ハウジング４４３の所定領域に外径の大きい大径部４４３ｅを設けているため、上側軸受部５４１ａの軸方向全体に亘って、上側軸受部５４１ａの径方向外方に位置するアウター軸受５４２と軸受ハウジング４４３との間に上部間隙部５４７が形成されている。
また、本例のブラシレスモータでは、インナー軸受５４１の外径とアウター軸受５４２の内径は軸方向の全体に亘って一定であるものの、アウター軸受５４２の所定領域に外径の小さい縮径部５４２ａを設けている。これにより、下側軸受部５４１ｂの軸方向全体に亘って、下側軸受部５４１ｂの径方向外方に位置するアウター軸受５４２と軸受ハウジング４４３との間に下部間隙部５４８が形成されている。
このように、本例のブラシレスモータでは、インナー軸受５４１のすべての軸受部（上部軸受部５４１ａと下部軸受部５４１ｂ）の軸方向全体に亘って、軸受部と軸受ハウジング４４３との間に全周に亘って間隙部（上部間隙部５４７と下部間隙部５４８）が設けられている。
このような構成によれば、インナー軸受５４１とアウター軸受５４２からなる二重構造の軸受を軸受ハウジング４４３内に圧入した際に、インナー軸受５４１の上部軸受部５４１ａと下部軸受部５４１ｂに径方向の大きな圧縮力が掛かるのを効果的に抑制できる。このため、上部軸受部５４１ａと下部軸受部５４１ｂの内径が収縮するのを抑制して、軸受部の内径精度を維持することができ、高精度な回転性能を得ることができる。 In the brushless motor of this example using the above bearing unit 540, since a large diameter portion 443e having a large outer diameter is provided in a predetermined region of the bearing housing 443, the upper bearing portion 541a is covered over the entire axial direction. An upper gap portion 547 is formed between the outer bearing 542 located on the outer side in the radial direction of the portion 541a and the bearing housing 443.
Further, in the brushless motor of this example, although the outer diameter of the inner bearing 541 and the inner diameter of the outer bearing 542 are constant over the entire axial direction, a reduced diameter portion 542a having a small outer diameter is provided in a predetermined region of the outer bearing 542. It is provided. As a result, a lower gap portion 548 is formed between the outer bearing 542 located outward in the radial direction of the lower bearing portion 541b and the bearing housing 443 over the entire axial direction of the lower bearing portion 541b.
As described above, in the brushless motor of this example, the entire circumference between the bearing portion and the bearing housing 443 over the entire axial direction of all the bearing portions (upper bearing portion 541a and lower bearing portion 541b) of the inner bearing 541. Gap portions (upper gap portion 547 and lower gap portion 548) are provided.
According to such a configuration, when a double-structured bearing composed of an inner bearing 541 and an outer bearing 542 is press-fitted into the bearing housing 443, it is radially connected to the upper bearing portion 541a and the lower bearing portion 541b of the inner bearing 541. It is possible to effectively suppress the application of a large compressive force. Therefore, it is possible to suppress the shrinkage of the inner diameters of the upper bearing portion 541a and the lower bearing portion 541b, maintain the inner diameter accuracy of the bearing portion, and obtain highly accurate rotational performance.

また、本例のブラシレスモータでは、アウター軸受５４２の下側領域に外径の小さい縮径部５４２ａを設けているため、二重構造の軸受を軸受ハウジング内に圧入するのが容易になり、モータ組立時の作業性を高めることができる。 Further, in the brushless motor of this example, since the reduced diameter portion 542a having a small outer diameter is provided in the lower region of the outer bearing 542, it becomes easy to press-fit the double-structured bearing into the bearing housing, and the motor. Workability during assembly can be improved.

以上、本発明の５つの実施形態例を説明したが、本発明はこれらの実施形態例に限定されるものではなく、本発明の趣旨を逸脱しない範囲で上記実施形態例を適宜に変形可能である。 Although the five embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and the above embodiments can be appropriately modified without departing from the spirit of the present invention. is there.

具体的には、軸受部の軸方向全体に亘って軸受部と軸受ハウジングとの間に間隙部が設けられる構造としては、実施形態例以外にも、例えば、上側軸受部の軸方向全体に亘って上側軸受部とアウター軸受との間に上側間隙部を設け、下側軸受部の軸方向全体に亘って下側軸受部とアウター軸受との間に下側間隙部を設けた構造を採ることもできる。 Specifically, as a structure in which a gap portion is provided between the bearing portion and the bearing housing over the entire axial direction of the bearing portion, for example, in addition to the embodiment, for example, over the entire axial direction of the upper bearing portion. A structure is adopted in which an upper gap is provided between the upper bearing and the outer bearing, and a lower gap is provided between the lower bearing and the outer bearing over the entire axial direction of the lower bearing. You can also.

また、実施形態例ではシャフトの被係止部に抜止め部材を係止させるロータ抜け止め構造を採用しているが、従来公知の任意の抜け止め構造を採用することもできる。 Further, in the embodiment, a rotor retaining structure for locking the retaining member to the locked portion of the shaft is adopted, but any conventionally known retaining structure can also be adopted.

以下に、この出願の優先基礎となる出願の出願当初の特許請求の範囲に記載した発明を付記する。
付記に記載した請求項の項番は、この出願の出願当初の特許請求の範囲のとおりである。
［原出願の出願当初の請求項１］シャフトを有するロータと、オイルを媒介として前記シャフトの径方向を支持する筒状の軸受と、上端が開口し内部に前記軸受を支持する軸受ハウジングとを備えたブラシレスモータにおいて、
前記軸受は、多孔質含油材からなるインナー軸受と、該インナー軸受の外周面に装着された多孔質含油材からなるアウター軸受とを有し、
前記インナー軸受は、径方向内方に凸に形成された軸受部を有し、
前記アウター軸受は、前記インナー軸受よりも含油率が大きく、
前記軸受部の軸方向全体に亘って、前記軸受部と該軸受部の径方向外方に位置する前記軸受ハウジングとの間に間隙部が設けられている、
ことを特徴とするブラシレスモータ。
［原出願の出願当初の請求項２］前記軸受部は、前記インナー軸受の上端部に設けられた上側軸受部と、前記インナー軸受の下端部に設けられた下側軸受部を有する、
ことを特徴とする請求項１に記載のブラシレスモータ。
［原出願の出願当初の請求項３］前記上側軸受部の軸方向全体に亘って、前記上側軸受部の径方向外方に位置する前記軸受ハウジングと前記アウター軸受との間に前記間隙部が設けられており、
前記下側軸受部の軸方向全体に亘って、前記下側軸受部と該下側軸受部の径方向外方に位置する前記アウター軸受との間に前記間隙部が設けられている、
ことを特徴とする請求項２に記載のブラシレスモータ。
［原出願の出願当初の請求項４］前記上側軸受部の軸方向全体に亘って、前記上側軸受部と該上側軸受部の径方向外方に位置する前記アウター軸受との間に前記間隙部が設けられており、
前記下側軸受部の軸方向全体に亘って、前記下側軸受部の径方向外方に位置する前記軸受ハウジングと前記アウター軸受との間に前記間隙部が設けられている、
ことを特徴とする請求項２に記載のブラシレスモータ。
［原出願の出願当初の請求項５］前記上側軸受部の軸方向全体に亘って、前記上側軸受部の径方向外方に位置する前記軸受ハウジングと前記アウター軸受との間に前記間隙部が設けられており、
前記下側軸受部の軸方向全体に亘って、前記下側軸受部の径方向外方に位置する前記軸受ハウジングと前記アウター軸受との間に前記間隙部が設けられている、
ことを特徴とする請求項２に記載のブラシレスモータ。
［原出願の出願当初の請求項６］前記上側軸受部の軸方向全体に亘って、前記上側軸受部と該上側軸受部の径方向外方に位置する前記アウター軸受との間に前記間隙部が設けられており、
前記下側軸受部の軸方向全体に亘って、前記下側軸受部と該下側軸受部の径方向外方に位置する前記アウター軸受との間に前記間隙部が設けられている、
ことを特徴とする請求項２に記載のブラシレスモータ。
［原出願の出願当初の請求項７］前記インナー軸受の外周面と前記アウター軸受の内周面との間に、軸方向に連通する溝が設けられている、
ことを特徴とする請求項１〜６のいずれか一項に記載のブラシレスモータ。
［原出願の出願当初の請求項８］前記アウター軸受の外周面と前記軸受ハウジングの内周面との間に、軸方向に連通する溝が設けられている、
ことを特徴とする請求項１〜７のいずれか一項に記載のブラシレスモータ。
［原出願の出願当初の請求項９］前記シャフトの外表面には、前記インナー軸受から前記軸受ハウジングの開口側に突出した部分に環状溝が形成されている、
ことを特徴とする請求項１〜８のいずれか一項に記載のブラシレスモータ。
［原出願の出願当初の請求項１０］前記軸受ハウジングの前記開口に環状の撥油部材が装着されており、前記撥油部材の下面は前記環状溝の上端よりも高い位置にある、
ことを特徴とする請求項９に記載のブラシレスモータ。 The inventions described in the scope of claims at the time of filing of the application that is the priority basis of this application are added below.
The item number of the claim described in the appendix is the scope of the claims at the time of filing of this application.
[Claim 1 at the time of filing the original application] A rotor having a shaft, a tubular bearing that supports the shaft in the radial direction via oil, and a bearing housing that has an open upper end and supports the bearing inside. In the equipped brushless motor
The bearing has an inner bearing made of a porous oil-impregnated material and an outer bearing made of a porous oil-impregnated material mounted on the outer peripheral surface of the inner bearing.
The inner bearing has a bearing portion formed so as to be convex inward in the radial direction.
The outer bearing has a higher oil content than the inner bearing.
A gap is provided between the bearing portion and the bearing housing located radially outward of the bearing portion over the entire axial direction of the bearing portion.
A brushless motor that features that.
[Claim 2 at the time of filing the original application] The bearing portion has an upper bearing portion provided at the upper end portion of the inner bearing and a lower bearing portion provided at the lower end portion of the inner bearing.
The brushless motor according to claim 1.
[Claim 3 at the time of filing the original application] The gap portion is formed between the bearing housing and the outer bearing located radially outward of the upper bearing portion over the entire axial direction of the upper bearing portion. It is provided,
The gap is provided between the lower bearing portion and the outer bearing located radially outward of the lower bearing portion over the entire axial direction of the lower bearing portion.
The brushless motor according to claim 2.
[Claim 4 at the time of filing the original application] The gap portion between the upper bearing portion and the outer bearing located radially outward of the upper bearing portion over the entire axial direction of the upper bearing portion. Is provided,
The gap is provided between the outer bearing and the bearing housing located radially outward of the lower bearing portion over the entire axial direction of the lower bearing portion.
The brushless motor according to claim 2.
[Claim 5 at the time of filing the original application] The gap portion is formed between the bearing housing and the outer bearing located radially outward of the upper bearing portion over the entire axial direction of the upper bearing portion. It is provided,
The gap is provided between the outer bearing and the bearing housing located radially outward of the lower bearing portion over the entire axial direction of the lower bearing portion.
The brushless motor according to claim 2.
[Claim 6 at the time of filing the original application] The gap portion between the upper bearing portion and the outer bearing located radially outward of the upper bearing portion over the entire axial direction of the upper bearing portion. Is provided,
The gap is provided between the lower bearing portion and the outer bearing located radially outward of the lower bearing portion over the entire axial direction of the lower bearing portion.
The brushless motor according to claim 2.
[Claim 7 at the time of filing the original application] A groove communicating in the axial direction is provided between the outer peripheral surface of the inner bearing and the inner peripheral surface of the outer bearing.
The brushless motor according to any one of claims 1 to 6, wherein the brushless motor.
[Claim 8 at the time of filing the original application] A groove communicating in the axial direction is provided between the outer peripheral surface of the outer bearing and the inner peripheral surface of the bearing housing.
The brushless motor according to any one of claims 1 to 7, wherein the brushless motor.
[Claim 9 at the time of filing the original application] An annular groove is formed on the outer surface of the shaft at a portion protruding from the inner bearing toward the opening side of the bearing housing.
The brushless motor according to any one of claims 1 to 8, wherein the brushless motor.
[Claim 10 at the time of filing the original application] An annular oil-repellent member is attached to the opening of the bearing housing, and the lower surface of the oil-repellent member is located higher than the upper end of the annular groove.
The brushless motor according to claim 9.

１０取付板
１１バーリング部
２０ステータ
２１ステータコア
２２コアカバー
２３コイル
３０ロータ
３１シャフト
３１ａ被係止部
３１ｂ環状溝
３２ロータケース
３２ａ円筒部
３２ｂ上面部
３２ｃバーリング部
３３駆動用マグネット
３４吸引用マグネット
１４０、２４０、３４０、４４０、５４０軸受ユニット
１４１、２４１、３４１、４４１、５４１インナー軸受
１４１ａ、２４１ａ、３４１ａ、４４１ａ、５４１ａ上部軸受部
１４１ｂ、２４１ｂ、３４１ｂ、４４１ｂ、５４１ｂ下部軸受部
１４１ｃ、２４１ｃ、３４１ｃ、４４１ｃ、５４１ｃ中逃げ部
１４１ｄ、２４１ｄ、４４１ｄ大径部
１４１ｅ、２４１ｅ、４４１ｅ縮径部
１４１ｆ、２４１ｆ、３４１ｆ、４４１ｆ、５４１ｆ溝
１４２、２４２、３４２、４４２、５４２アウター軸受
１４２ａ、２４２ａ、３４２ａ、５４２ａ縮径部
１４２ｂ、２４２ｂ、３４２ｂ、５４２ｂ大径部
１４２ｃ、２４２ｃ、３４２ｃ、４４２ｃ、５４２ｃ溝
１４３、４４３軸受ハウジング
１４３ａ筒部
１４３ａ１鍔
１４３ｂ第１底部
１４３ｃ第２底部
１４４スラスト板
１４５抜止め部材
１４６撥油部材
１４７、２４７、３４７、４４７、５４７上部間隙部
１４８、２４８、３４８、４４８、５４８下部間隙部
４４３ｄ段差部
４４３ｅ大径部
４４３ｆ小径部 10 Mounting plate 11 Burling part 20 Stator 21 Stator core 22 Core cover 23 Coil 30 Rotor 31 Shaft 31a Locked part 31b Circular groove 32 Rotor case 32a Cylindrical part 32b Top surface part 32c Burling part 33 Drive magnet 34 Suction magnet 140, 240 , 340, 440, 540 Bearing Units 141, 241, 341, 441, 541 Inner Bearings 141a, 241a, 341a, 441a, 541a Upper Bearings 141b, 241b, 341b, 441b, 541b Lower Bearings 141c, 241c, 341c, 441c , 541c Medium relief part 141d, 241d, 441d Large diameter part 141e, 241e, 441e Reduced diameter part 141f, 241f, 341f, 441f, 541f Groove 142, 242, 342, 442, 542 Outer bearing 142a, 242a, 342a, 542a Diameter 142b, 242b, 342b, 542b Large diameter 142c, 242c, 342c, 442c, 542c Groove 143, 443 Bearing housing 143a Cylinder 143a1 flange 143b 1st bottom 143c 2nd bottom 144 Thrust plate 145 Element
147, 247, 347, 447, 547 Upper gap 148, 248, 348, 448, 548 Lower gap 443d Step 443e Large diameter 443f Small diameter

Claims

In a brushless motor including a rotor having a shaft, a tubular bearing that supports the shaft in the radial direction via oil, and a bearing housing that has an open upper end and supports the bearing inside.
The bearing has an inner bearing made of a porous oil-impregnated material and an outer bearing made of a porous oil-impregnated material mounted on the outer peripheral surface of the inner bearing.
The inner bearing has a plurality of bearing portions formed convex inward in the radial direction, and has a plurality of bearing portions.
The outer bearing has a higher oil content than the inner bearing.
The outer bearing, the slightly longer axially than the inner bearing, and an upper end surface of the said inner bearing outer bearing has a substantially flush,
A gap is provided between the bearing portion and the bearing housing located radially outward of the bearing portion over the entire axial direction of all the bearing portions.
A brushless motor that features that.

The bearing portion has an upper bearing portion provided at the upper end portion of the inner bearing and a lower bearing portion provided at the lower end portion of the inner bearing, and the upper bearing portion and the bearing portion are outside the radial direction. An upper gap is provided between the bearing housing located on the side, and a lower gap is provided between the lower bearing and the bearing housing located radially outward of the bearing. ing,
The brushless motor according to claim 1.

The upper gap portion is provided between the bearing housing located radially outward of the upper bearing portion and the outer bearing over the entire axial direction of the upper bearing portion.
The lower gap portion is provided between the lower bearing portion and the outer bearing located radially outward of the lower bearing portion over the entire axial direction of the lower bearing portion.
The brushless motor according to claim 2.

The upper gap portion is provided between the bearing housing located radially outward of the upper bearing portion and the outer bearing over the entire axial direction of the upper bearing portion.
The lower gap portion is provided between the bearing housing located radially outward of the lower bearing portion and the outer bearing over the entire axial direction of the lower bearing portion.
The brushless motor according to claim 2.

A groove that communicates in the axial direction is provided between the outer peripheral surface of the inner bearing and the inner peripheral surface of the outer bearing.
The brushless motor according to any one of claims 1 to 4, wherein the brushless motor.

A groove that communicates in the axial direction is provided between the outer peripheral surface of the outer bearing and the inner peripheral surface of the bearing housing.
The brushless motor according to any one of claims 1 to 5, wherein the brushless motor.

An annular groove is formed on the outer surface of the shaft at a portion protruding from the inner bearing toward the opening side of the bearing housing.
The brushless motor according to any one of claims 1 to 6, wherein the brushless motor.

An annular oil-repellent member is attached to the opening of the bearing housing, and the lower surface of the oil-repellent member is located higher than the upper end of the annular groove.
The brushless motor according to claim 7.