Motor

Abstract

The present invention provides a motor having: a shaft having one end and the other end; a stator; a rotor surrounded by the stator; and a housing having a bottom portion, the rotor having an annular cylindrical portion and an annular disk portion formed of a non-magnetic body connecting the annular cylindrical portion and the shaft, and the bottom portion of the housing having a portion on the annular cylindrical portion side and a portion on the shaft side in the radial direction of the shaft. A stator fixing portion is provided on a portion of a bottom portion of the housing on a side of the annular cylinder portion, the bottom portion of the housing extending in a direction intersecting a longitudinal direction of the shaft, and a disk portion formed of the non-magnetic body has an annular portion supporting the annular cylinder portion. A cylindrical portion of the rotor extending from an annular portion of the disk portion in a longitudinal direction of the shaft is formed of a magnetic body.

Description

[0001] This application is a divisional application of patent application No. 201911048057.8, filed on October 30, 2019, entitled "Electric Motor". Technical Field

[0002] This invention relates to a brushless motor that can be mounted on a suspended mobile body, such as a drone. Background Technology

[0003] The impact on the drone's body during landing can damage the bearings of the motors that drive the blades. Therefore, in cases of significant landing impact, the motors must be replaced each time, resulting in cumbersome replacement procedures and increased costs.

[0004] (Existing technical documents) (Patent Documents) Patent Document 1: Japanese Patent Application Publication No. 2018-117429 Summary of the Invention

[0005] (The problem the invention aims to solve) Therefore, the present invention was made in view of the above background research, and its purpose is to provide a motor that can suppress cumbersome operation and increased cost even when used in applications such as drones and other suspended mobile bodies that are prone to large impacts.

[0006] (Solutions for solving the problem) The above-mentioned problems are solved by the following invention. That is, the motor of the present invention has: a shaft; a replaceable component (Cartridge) having a plurality of bearings supporting the shaft and a sleeve surrounding the bearings; and a housing having a bottom for resisting external impact and a mounting portion disposed on the bottom, the bottom of the housing extending in a direction intersecting the length direction of the shaft, the replaceable component being detachably mounted relative to the mounting portion.

[0007] In the motor of the present invention, the replaceable component, together with the shaft, can be detachably mounted relative to the mounting portion.

[0008] Furthermore, in the motor of the present invention, the component forming the shaft may have a smaller specific gravity than the component forming the bearing, and the shaft may be hollow.

[0009] Furthermore, in the motor of the present invention, one end of the shaft on the bottom side may be located closer to the inside of the housing than the bottom.

[0010] In the motor of the present invention, the mounting portion may have a cylindrical portion for accommodating the replaceable component. In this case, in the length direction of the shaft, the cylindrical portion may have one end on the bottom side and another end on the opposite side of the bottom. The replaceable component may be fixed by the fixing member clamping the bottom.

[0011] Furthermore, in the motor of the present invention, at least a portion of the space between the replaceable component and the housing may contain an elastic member. In this case, preferably, the elastic member may be sandwiched between a portion of the replaceable component and a portion of the housing that are opposite each other in the longitudinal direction of the shaft, or the elastic member may be sandwiched between the replaceable component and the bottom or between the replaceable component and the fixing member in the longitudinal direction of the shaft.

[0012] In the motor of the present invention, a rotor may be detachably fixed to the shaft. In this case, the motor has a stator surrounded by the rotor, and the rotor has a disc portion detachably fixed to the shaft. Attached Figure Description

[0013] Figure 1 This is a cross-sectional view of an external rotor type motor according to an embodiment of the present invention.

[0014] Figure 2 This is a three-dimensional cross-sectional view of an electric motor as an example embodiment of the present invention.

[0015] Figure 3 From Figure 2 A three-dimensional cross-sectional view of the replaceable component is extracted separately.

[0016] Figure 4 It is an exploded view used to illustrate the state of the shell with replaceable parts installed.

[0017] Figure 5 From Figure 1 The cross-sectional view of the replaceable parts and shell is extracted separately.

[0018] Figure 6 It is an exploded diagram used to illustrate the state of a rotor mounted on a shaft.

[0019] Figure 7 This is a cross-sectional view of an internal rotor type motor according to a variation of the present invention. Detailed Implementation

[0020] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Figure 1 This is a cross-sectional view of the motor 1 according to an embodiment of the present invention. Figure 2 Viewed from an oblique angle and Figure 1A three-dimensional cross-sectional view of the same section. Additionally, in the description of this embodiment, when "above" or "below" is mentioned, it refers to... Figure 1 and Figure 2 The vertical relationship in the equation is not necessarily consistent with the vertical relationship in the direction of gravity.

[0021] The motor 1 comprises a stator 2, a rotor 3, a replaceable component 4, and a housing 5, forming an external rotor type brushless motor. The stator 2 includes teeth 23 extending outwards and coils 22 wound around the teeth 23. The rotor 3 includes magnets 31 on the outer diameter side of the stator 2 opposite to the teeth 23. The replaceable component 4 is equipped with a shaft 41 serving as a rotation axis, which is fixed at the center of the rotor 3. The housing 5 fixes and accommodates the stator 2. The rotor 3 is rotatable relative to the stator 2.

[0022] The stator 2, which is surrounded by the rotor 3, has a stator core 21 including teeth 23 and coils 22.

[0023] The stator core 21 is a laminate of silicon steel plates, etc., including an annular portion (core) 24 coaxially arranged with the shaft 41, and a plurality of teeth (pole portions) 23 formed in a radial manner extending from the annular portion 24 to the outer diameter side.

[0024] The coil 22 is wound around each of the plurality of teeth 23. The stator core 21 and the coil 22 are insulated by an insulator (not shown) formed of an insulator. Alternatively, instead of using an insulator, an insulating film can be coated on the surface of the stator core to achieve insulation from the coil.

[0025] The rotor 3 includes a magnet 31 and a rotor yoke 32. The rotor yoke 32 includes a cylindrical portion 33 at its outer edge and a disk portion 34 connecting the shaft 41 and the cylindrical portion 33. The cylindrical portion 33 extends from the outer edge of the disk portion 34 in a vertical direction (in... Figure 1 and Figure 2 The cylinder is upright (with the center facing downwards) and centered on the axis of shaft 41, and is in a state of surrounding the stator 2.

[0026] The rotor yoke (core) 32, formed of a magnetic material, functions to prevent leakage of the magnetic field within the rotor yoke 32. Furthermore, while the cylindrical portion 33 and the disc portion 34 of the rotor yoke 32 are formed of magnetic materials, they can also be formed of non-magnetic materials if there are no issues with their properties. For example, the cylindrical portion 33 and the disc portion 34 can be integrally formed of aluminum, or either the cylindrical portion 33 or the disc portion 34 can be formed of a magnetic material, while the other is formed of a non-magnetic material.

[0027] Magnet 31 is mounted on the inner circumferential surface of cylindrical portion 33 opposite to stator 2. Magnet 31 has a ring shape, and regions magnetized as N poles and regions magnetized as S poles are arranged alternately along the circumferential direction at a fixed period.

[0028] In this embodiment, the replaceable component 4 includes a shaft 41, two bearings 42 and 42', and a sleeve 43. Figure 2 Remove the replaceable part 4 separately and in Figure 3 The cross-sectional three-dimensional view is shown in the middle.

[0029] Shaft 41 is made of aluminum, for example, to achieve lightweighting, and as... Figure 1 As shown, it becomes a hollow state (more specifically, a cylindrical state).

[0030] On shaft 41, a stepped portion 41c is provided at approximately the center of the axial direction. The outer diameter of the upper side of the stepped portion 41c is smaller than the outer diameter of the lower side.

[0031] Two bearings 42 and 42' are installed side by side below the shaft 41 and spaced apart. In addition, in the following description, when referred to only as "bearing 42", unless otherwise specified, it refers to the common content of the two bearings 42 and 42' (including the outer ring 42a, inner ring 42b and bearing balls 42c that are the constituent components of bearing 42).

[0032] Bearing 42 is a so-called ball bearing, comprising outer rings 42a and 42a', inner rings 42b and 42b', and bearing balls 42c and 42c', which are sandwiched between the outer ring 42a and the inner ring 42b. The bearing balls 42c roll between the outer ring 42a and the inner ring 42b, thereby significantly reducing the rotational resistance of the inner ring 42b to the outer ring 42a. Bearing 42 is formed of a hard metal such as iron or a ceramic component for this function.

[0033] Sleeve 43 is a cylindrical component, for example, made of plastic or metal. The outer circumferential surface of sleeve 43 is smooth, but the inner circumferential surface of sleeve 43 has a protrusion (small-diameter inner circumferential portion) 43a and a recess (large-diameter inner circumferential portion) 43b. The protrusion is located at the center of the inner circumferential surface and protrudes axially toward the central axis. The recesses (with large diameter inner circumferential portions) 43b located on both sides of the protrusion are recessed in the axial direction. Hereinafter, the protrusion will be referred to as the small-diameter portion, and the recesses as the large-diameter portion.

[0034] Furthermore, the sleeve 43 can be integrally formed using known methods in a shape having a small inner diameter portion 43a and a large inner diameter portion 43b. However, for example, the sleeve 43 can be formed from two or more components by inserting a small-diameter round tube into a large-diameter round tube. The inner diameter of the small-diameter round tube is the same as the inner diameter of the small inner diameter portion 43a, and the outer diameter of the small-diameter round tube is the same as the inner diameter of the large inner diameter portion 43b. The inner diameter of the large-diameter round tube is the same as the inner diameter of the large inner diameter portion 43b. As a result, the small-diameter round tube is located approximately at the center of the large-diameter round tube in the axial direction. In addition, the small-diameter round tube can also be formed using a different component than the large-diameter round tube, for example, an elastic component such as a helical spring can be used.

[0035] The shaft 41 has one end 41a on the bottom 51 side of the housing 5 (described later) and another end 41b on the opposite side. Two bearings 42 and 42' are located side by side near one end 41a of the shaft 41. The shaft 41 is fitted into and fixed with the inner rings 42b of the two bearings 42 and 42', and is supported by the two bearings 42 and 42'. Therefore, the shaft 41 is rotatably supported by the housing 5. In addition, a retaining ring 44 is installed on the shaft 41 at a position closer to one end 41a than the bearings 42 to limit the axial movement of the shaft 41. Figure 1 The upward movement (disengagement of shaft 41). Additionally, if a metal washer is used instead of retaining ring 44, the shaft 41 can be more securely prevented from detaching.

[0036] On the other hand, the outer rings 42a and 42a' of the two bearings 42 and 42' are respectively embedded in the two large inner diameter portions 43b of the sleeve 43 and are fixedly supported. Therefore, in the replaceable part 4, the shaft 41 is supported with free rotation relative to the sleeve 43.

[0037] The housing 5 has a generally flat bottom 51, a mounting portion 54, and a stator fixing portion 55. The replaceable part 4 is detachably mounted on the mounting portion 54, and the stator 2 is fixed to the stator fixing portion 55. A surface is formed on the bottom 51 to withstand external impacts. Furthermore, the bottom 51 extends in a direction intersecting the longitudinal direction (axial direction) of the shaft.

[0038] exist Figure 4 An exploded view illustrating the state is shown, under which the replaceable part 4 is mounted on the housing 5. Furthermore, from... Figure 1 The replaceable parts 4 and 5 can be extracted separately and placed in the middle. Figure 5 The figure is shown in cross-section.

[0039] The bottom 51 has a circular opening 51a around its periphery at the position where it intersects the longitudinal direction of the shaft 41 (the center of the bottom 51). Around this opening is a ring-shaped flat plate region (flat plate portion) 51b, and further a ring-shaped inclined region (inclined portion) 51c. This inclined region is connected to the outer edge and slopes upwards towards the outer periphery (towards the stator 2). Viewed through the opening 51a, the shaft 41 can be seen from below the motor 1.

[0040] A cylindrical portion 52 is provided at the bottom 51 to accommodate part or all of the replaceable component 4. In addition to an opening 51a, an annular protrusion 51d is formed on the inner side (center side) of the cylindrical portion 52. An annular elastic member 56a is attached to the upper surface (inner side of the shell 5) of the protrusion 51d.

[0041] The stator fixing portion 55 is a flat cylindrical shape extending from the bottom 51 toward the stator 2 (axially upward from the shaft 41). A stepped portion 55a is formed on the outer periphery of the stator fixing portion 55, and this stepped portion 55a is formed in the middle of the stator fixing portion 55 to reduce the thickness of the outer diameter of the stator fixing portion 55. The inner periphery of the annular portion 24 is fitted into this stepped portion 55a, and the stator 2 is fixed to the housing 5 by known methods such as bonding. The stator 2 is in a state of surrounding the replaceable component 4.

[0042] The mounting portion 54 includes a cylindrical portion 52 extending from the bottom 51 toward the stator 2 (axially above the shaft 41) and an annular fixing member 53 separate from and independent of the cylindrical portion 52. The cylindrical portion 52 has one end on the side of the bottom 51 and another end on the opposite side of the bottom 51, and the fixing member 53 is provided at the other end of the cylindrical portion 52.

[0043] The fixing member 53 has a cylindrical portion (hereinafter referred to as the cylindrical portion) 53a and an annular portion (hereinafter referred to as the pressing piece portion) 53b that protrudes in a circular shape from one end of the cylindrical portion 53a toward the central axis. A spiral groove (not shown) is provided on the inner circumferential surface of the cylindrical portion 53a, which can be threadedly engaged with a threaded spiral groove (not shown) provided above the outer circumferential surface of the cylindrical portion 52.

[0044] Furthermore, an annular elastic member 56b is attached to the lower surface of the pressing plate portion 53b (the surface facing the bottom surface 51). The lower surface of the pressing plate portion 53b is opposite to the upper end of the sleeve 43. The elastic members 56a and 56b are formed of elastic materials, such as natural rubber, synthetic rubber, silicone rubber, elastomers, etc. In this embodiment, the elastic members 56a and 56b are objects formed of the same material and have the same shape, but they can also be formed of other materials, and their thickness, diameter, and other shapes can also be different.

[0045] The replaceable component 4 (sleeve 43) is mounted on the housing 5 by being received in the cylindrical portion 52. Furthermore, the replaceable component 4 (sleeve 43) is clamped between and fixed to the bottom 51 by threading the fixing member 53 onto the upper part (opposite end to the bottom 51) of the cylindrical portion 52. In other words, the replaceable component 4 is fixed by being clamped between the fixing member 53 and the bottom 51. As described above, the replaceable component 4, together with the shaft 41, is detachably mounted on the mounting portion 54.

[0046] At this time, along the length direction (axial direction) of the shaft 41, an elastic member 56a is sandwiched between the lower end of the sleeve 43 and the bottom 51 (protrusion 51d), and an elastic member 56b is sandwiched between the upper end of the sleeve 43 and the fixing member 53. The elastic members 56a and 56b can suppress the transmission of external impacts to the replaceable part 4.

[0047] With the replaceable part 4 installed in the housing 5, one end 41a of the shaft 41 is located further inside the housing 5 than the bottom 51. Figure 1 The position is on the upper side. That is, one end 41a of the shaft 41 is in a state of floating from the bottom 51. Therefore, it is possible to suppress, for example, impacts from below that are directly transmitted to the shaft 41.

[0048] On the shaft 41 of the replaceable part 4 mounted on the housing 5, between the other end 41b on the opposite side of the bottom 51 and the bearing 42', the rotor 3 is detachably fixed to the shaft 41. Figure 6 This is an exploded view illustrating the state in which the rotor 3 is mounted on shaft 41. Additionally, in Figure 6 The stator 2 and the shell 5 are omitted from the diagram.

[0049] If the shaft 41 is inserted into the hole (hereinafter referred to as shaft hole 35) on the central shaft of the rotor 3 from the other end 41b, the inner circumference of the shaft hole 35 abuts against the stepped portion 41c of the shaft 41. Next, the shaft 41 is inserted into the shaft hole 36a of the mounting member 36, and the threaded hole 37 of the rotor 3 and the threaded hole 36b of the mounting member 36 are fastened with screws at 4 points, thereby fixing the rotor 3 to the shaft 41. The rotor 3 or the mounting member 36 is fixed to the shaft 41 by a fixing method not shown to restrict movement in the direction of rotation, and the shaft 41 rotates together with the rotor 3.

[0050] The assembly described above is thus completed. Figure 1 , Figure 2 The motor 1 of this embodiment with the structure shown.

[0051] According to the motor of this embodiment, the replaceable part 4 can be pulled out from the mounting part 54 of the housing 5 simply by removing the rotor 3 from the shaft 41 and the fixing member 53 from the upper end of the cylindrical part 52. The installation of the replaceable part 4 is also as easy as described above. In other words, the replaceable part 4 can be easily installed and removed from the motor of this embodiment.

[0052] For example, in applications involving hovering mobile bodies such as drones, bearings, being precision components, are prone to damage upon landing due to significant impact. Previously, in cases of damage, the entire motor had to be replaced. However, in the motor according to this embodiment, the replaceable component 4 is detachably mounted on the mounting section 54. In this state, the shaft 41 is supported on the replaceable component 4. Therefore, by simply preparing the replaceable component 4, which supports the shaft 41, as a replacement part and replacing it, the damaged bearing can be restored, and the motor can be rebuilt. Thus, motor replacement can be completed simply and cost-effectively by replacing the replaceable component 4, significantly reducing cumbersome operations and costs.

[0053] When assembling a complete motor, the large number of parts and numerous factors affecting performance and tolerances easily lead to individual performance variations in each motor. Replacing the entire motor often necessitates readjustment of the drive, resulting in cumbersome operations and increased costs. However, by utilizing replaceable component 4, which has fewer parts and is easily manufactured with high precision and homogeneity, individual variations are less likely to occur. Therefore, in this embodiment where only replaceable component 4 needs to be replaced, not only is readjustment of the drive unnecessary before and after replacement, but it also offers the added value of extended motor lifespan, reduced mechanical load leading to performance improvements, and reduced vibration and noise caused by uneven rotation.

[0054] Furthermore, regarding the impact load on the outer peripheral surface of the motor that could cause bearing damage, compared to conventional structures where the bearing is directly mounted on the outer peripheral components, in the motor 1 of this embodiment, the bearing 42 is assembled via a sleeve 43. Therefore, the impact is difficult to be directly transmitted to the bearing 42, and the sleeve 43 is an independent component. Thus, in this embodiment, the strength against external impacts can be improved.

[0055] Furthermore, in the motor 1 of this embodiment, elastic members 56a and 56b are sandwiched between at least a portion of the replaceable part 4 and the housing 5. As described above, the replaceable part 4 and the housing 5 are formed with different components, therefore, by sandwiching the elastic members 56a and 56b as impact buffers between them, the bearing 42 can be protected.

[0056] In particular, when used for drone applications, landing is susceptible to axial impact loads. In this embodiment, an elastic member 56a is sandwiched between a portion of the replaceable part 4 (sleeve 43) and the bottom 51, and an elastic member 56b is sandwiched between a portion of the replaceable part 4 (sleeve 43) and the fixing member 53. In this state, when viewed axially along the shaft 41, i.e., in the longitudinal direction (axial direction) of the shaft 41, the replaceable part 4 and the housing 5 are opposite each other, thus further improving the impact resistance to axial impact loads.

[0057] Furthermore, in the motor 1 of this embodiment, an elastic member 56a is provided between the sleeve 43 and the bottom 51, and an elastic member 56b is provided between the sleeve 43 and the fixing member 53. However, the elastic member may be provided between the outer ring 42a and the bottom 51, or between the outer ring 42a and the fixing member 53, instead of the sleeve 43. Preferably, the elastic member is provided between the sleeve 43 and the outer ring 42a or the bottom 51, or between the sleeve 43 and the outer ring 42a or the fixing member 53. Furthermore, the elastic member can be provided in a manner that covers the entire replaceable part 4. In other words, as long as an elastic member is sandwiched between at least a portion of the replaceable part 4 and the housing 5, an improved impact resistance to external impacts can be expected.

[0058] Furthermore, in the motor according to this embodiment, one end 41a of the shaft 41 is located on the inner side of the housing 5, closer to the bottom 51. Figure 1 The shaft is positioned above the bottom 51 and floats up, thus suppressing the direct transmission of impacts from below to the shaft 41, thereby further improving its resistance to axial impact loads.

[0059] Furthermore, in the motor 1 of this embodiment, the shaft 41 can be observed from below the motor 1 through the opening in the region inside (central shaft side) of the cylindrical portion 52 of the bottom 51. However, in the case where there is no opening or the opening is narrow and the bottom is located opposite one end 41a of the shaft 41, the same effect as in this embodiment can be achieved as long as the bottom is separated from one end of the shaft. Such a state where the bottom is separated from one end of the shaft includes the concept described in this invention of "one end on the bottom side is located in a position closer to the inside of the shell than the bottom".

[0060] Furthermore, in the motor 1 of this embodiment, the shaft 41 is made of, for example, aluminum to achieve weight reduction, and its specific gravity is less than that of the component (iron) forming the bearing 42. By making the shaft 41 lighter, damage to the bearing 42 when subjected to external impact can be reduced.

[0061] Furthermore, in this embodiment, the shaft 41 is hollow (more preferably cylindrical), which further reduces damage. In addition, when using the same material as the bearing 42 or with the same specific gravity, as long as the shaft 41 is hollow, the shaft 41 can be made lighter, thereby reducing damage to the bearing 42 when subjected to external impact.

[0062] Furthermore, while the electrical mechanism in this embodiment is an external rotor type brushless motor, the present invention can also be applied to motors other than brushless motors. Moreover, the present invention can also be applied to internal rotor type motors. Figure 7 The diagram shows a modified example of an internal rotor type motor, illustrated by a cross-sectional view. Figure 7 In China, for the sake of Figure 1 The components shown in the embodiments have the same function, the same structure, and the same shape, and are labeled with the same meaning. Figure 1 (Implementation methods) use the same symbols, and their detailed descriptions are omitted.

[0063] like Figure 7 As shown, in the internal rotor type motor 101, a rotor 103 is disposed inside the stator 102. This rotor 103 has a rotor yoke 132, and annular magnets 131 are mounted on the outer circumferential surface of the rotor yoke 132. Furthermore, since the rotor yoke 132 is located inside the stator 102, the outer diameter of the cylindrical portion 133 is smaller than the outer diameter of the annular portion 124 of the stator 102, and the outer diameter of the disc portion 134 is also of a corresponding size.

[0064] The stator 102, which is configured to surround the rotor 3, includes: a stator core 121, which includes an annular portion (core) 124 coaxially arranged with the shaft 41 and a plurality of teeth (pole portions) 123 formed in such a way as to extend from the annular portion 124 toward the shaft 41 (center); and a coil 122 wound around each of the plurality of teeth 123.

[0065] In housing 105, the structure around the mounting portion 54 is the same as that of housing 5 in the embodiment, but housing 105 differs from housing 5. In housing 105, the stator fixing portion 155 is located at the outer edge of the inclined region 151c, and the stepped portion 155a is formed on the inner circumferential side of the stator fixing portion 155. The replaceable component 4 is detachably mounted on the mounting portion 54, and the stator 102 is fixed to the stator fixing portion 155. These differences in configuration result in different sizes and shapes of the flat plate region 151b and the inclined region 151c.

[0066] like Figure 7 As shown in the modified example, the configuration of the present invention can be applied to the internal rotor type motor 101 without any problems, and according to this modified example, the effect of easy installation and removal of the replaceable part 4 can be achieved, and the various other accompanying effects of the present invention described in the embodiments can also be achieved.

[0067] The preferred embodiments of the present invention have been described above, but the motor of the present invention is not limited to the configuration of the above embodiments. For example, in the above embodiments, the case of having two bearings 42, 42' is listed, but the number of bearings included in the replaceable parts may be three or more.

[0068] In the above embodiments, the replaceable component is described in one configuration. In this configuration, the replaceable component 4 includes a shaft 41. However, in this invention, the replaceable component may also be configured without a shaft but with multiple bearings and sleeves. Even in the configuration without a shaft, if the bearing needs to be replaced due to damage or other reasons, it can be easily replaced using the replaceable component.

[0069] Furthermore, by making the shaft and the replaceable parts separate entities, it is possible, for example, to replace only the replaceable part containing the damaged bearing and continue using the shaft in a usable state. If it is also desired to replace the shaft, simply prepare the replacement shaft in advance along with the replaceable parts, pre-press the bearing in, and then replace the replaceable part supporting the shaft.

[0070] Even if the replaceable part does not include the shaft, the bearing can be assembled into the sleeve with high precision, making it easy to manufacture with high precision and uniformity. Therefore, when only replaceable part 4 is replaced, not only is it possible to avoid readjusting the drive before and after replacement, but also to expect performance improvements such as longer motor life, reduced mechanical load, and reduced vibration and noise caused by uneven rotation.

[0071] Of course, from the perspective of work efficiency, in the configuration illustrated in the above embodiments, a single replaceable component is configured in the form of a shaft, and the entire replaceable component supporting the shaft can be easily replaced, so it is preferred.

[0072] Furthermore, in the above embodiments, examples are given of elastic members 56a and 56b being installed (attached) to the constituent members (protrusion 51d of bottom 51 and pressing piece 53b of fixing member 53) on the side of shell 5. However, the elastic members are not necessarily installed on the constituent members on the side of shell 5. They can be installed on the constituent members on the side of replaceable part 4 (e.g., sleeve 43), or they can be not installed at all, but simply become independent parts in the clamped state.

[0073] Furthermore, while achieving the effects of the present invention based on detachable and replaceable parts, the replaceable parts and the housing may not be sandwiched with an elastic member, but it is of course preferable to sandwich an elastic member.

[0074] Furthermore, as for shell 5, the bottom 51 is described as having a flat region (flat region 51b), but the bottom of the shell can be entirely flat, or it can be non-flat and instead, for example, gently dome-shaped or formed only by sloping surfaces. Regardless of whether there is a flat region, as long as the whole has a surface that can constitute the bottom of the shell, that surface is included in the concept of "flat or substantially flat bottom".

[0075] Furthermore, in this embodiment, a case is described in which the sleeve 43 has a small inner diameter portion 43a and a large inner diameter portion 43b and the outer circumference diameters are the same. However, in this invention, the shape of the sleeve is not limited. As long as it is configured as a mounting part that can support the outer ring of multiple bearings and can be installed and removed from the housing, it can be used without any problems.

[0076] Furthermore, those skilled in the art can appropriately modify the motor of the present invention based on prior knowledge and understanding. Any modifications that result in a motor that retains the structure of the present invention are naturally included within the scope of this invention.

[0077] (Label Explanation) 1. 101 Motor; 2. 102 Stator; 21. 121 Stator core; 22. 122 Coil; 23. 123 Tooth section; 24. 124 Annular section; 3. 103 Rotor; 31. 131 Magnet; 32. 132 Rotor yoke; 33. 133 Cylindrical section; 34. 134 Disc section; 35 Shaft hole; 36 Mounting part; 36a Shaft hole; 4 Replaceable parts; 41 Shaft; 41a One end; 41b The other end; 41c Stepped section; 42. 42' Bearing; 42a. 42a' Outer ring; 42b. 42b' Inner ring; 42c. 42c' Bearing ball; 43 Sleeve; 43a Small inner diameter section; 43b Large inner diameter section; 44 Snap ring; 5. 105 Housing; 51. 151 Bottom; 51a Opening; 51b, 151b Flat plate area; 51c, 151c Inclined area; 51d Protrusion; 52 Cylindrical part; 53 Fixing member; 54 Mounting part; 55, 155 Stator fixing part; 55a, 155a Stepped part; 56a, 56b Elastic member.

Claims

1. An electric motor, comprising: a shaft having one end portion and another end portion; a stator; a rotor surrounded by the stator; and a housing having a bottom portion, the rotor having a ring-shaped cylindrical portion, a ring-shaped disc portion connecting the ring-shaped cylindrical portion and the shaft and formed of a non-magnetic material, the bottom portion of the housing having a portion on the ring-shaped cylindrical portion side and a portion on the shaft side in a radial direction of the shaft, the portion of the bottom portion of the housing on the ring-shaped cylindrical portion side being provided with a stator fixing portion, the bottom portion of the housing extending in a direction intersecting a length direction of the shaft, the stator being fixed to the stator fixing portion, the disc portion formed of the non-magnetic material having a ring-shaped portion supporting the ring-shaped cylindrical portion, and the cylindrical portion of the rotor extending from the ring-shaped portion of the disc portion toward the length direction of the shaft being formed of a magnetic material.

2. The electric motor according to claim 1, wherein a plurality of ball bearings having a portion supporting the one end portion side of the shaft and a cylindrical portion surrounding the plurality of ball bearings, the rotor being located between the another end portion of the shaft and the plurality of ball bearings and fixed to the portion of the shaft, an inner peripheral surface of the cylindrical portion having a plurality of recessed portions recessed in a radial direction of the shaft, the plurality of ball bearings being fixed to the plurality of recessed portions, the cylindrical portion being provided to the portion on the shaft side of the bottom portion of the housing, and a portion of the bottom portion of the housing between the cylindrical portion and the stator fixing portion.

3. An electric motor, comprising: a shaft having one end portion and another end portion; a plurality of ball bearings having a portion supporting the one end portion side of the shaft and a cylindrical portion surrounding the plurality of ball bearings; a rotor located between the another end portion of the shaft and the plurality of ball bearings and fixed to the portion of the shaft; a stator; and a housing having a bottom portion, the bottom portion of the housing having a portion on the rotor side and a portion on the shaft side in a radial direction of the shaft, the rotor being surrounded by the stator, an inner peripheral surface of the cylindrical portion having a plurality of recessed portions recessed in a radial direction of the shaft, the plurality of ball bearings being fixed to the plurality of recessed portions, a stator fixing portion being provided to the portion on the rotor side of the bottom portion of the housing, the sleeve being provided to the portion on the shaft side of the bottom portion of the housing, a portion of the bottom portion of the housing between the cylindrical portion and the stator fixing portion extending in a direction intersecting a length direction of the shaft, the stator being fixed to the stator fixing portion, the rotor having a cylindrical portion, a disc portion connecting the cylindrical portion and the shaft and formed of a non-magnetic material, the disc portion having a ring-shaped outer edge, and the cylindrical portion of the rotor extending from the ring-shaped outer edge toward the length direction of the shaft being formed of a magnetic material.

4. The electric motor according to any one of claims 1 to 3, wherein a space is surrounded by the cylindrical portion, a portion of the bottom portion of the housing between the cylindrical portion and the stator fixing portion, and the disc portion of the non-magnetic material.

5. The electric motor according to any one of claims 1 to 4, wherein a mount fixed to the rotor is provided. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 6. A suspended mobile body having the electric motor according to any one of claims 1 to 5.

7. An electric motor having: a shaft having one end portion and another end portion; a plurality of bearings supporting a portion of the one end portion side of the shaft; a cylindrical portion surrounding the plurality of bearings; a rotor located between the other end portion of the shaft and the plurality of bearings and fixed to a portion of the shaft; a stator surrounded by the rotor; and a housing having a bottom portion, the rotor having a magnet, a cylindrical portion supporting the magnet, and a disc portion connecting the cylindrical portion and the shaft, the cylindrical portion of the rotor being formed of a magnetic material, an inner peripheral surface of the cylindrical portion having a plurality of recessed recesses in a radial direction of the shaft, the plurality of bearings being fixed to the plurality of recessed recesses, a portion of the bottom portion on the shaft side having the cylindrical portion in a length direction of the shaft, the cylindrical portion extending from the bottom portion in the length direction of the shaft, a portion of the bottom portion on the rotor side having a cylindrical stator fixing portion, the stator being fixed to the cylindrical stator fixing portion, the cylindrical stator fixing portion extending from the bottom portion in the length direction of the shaft, an outer peripheral surface of the cylindrical portion being located radially inward of an inner peripheral surface of the cylindrical stator fixing portion, and the bottom portion of the housing located between the cylindrical portion and the cylindrical stator fixing portion extending in a direction intersecting the length direction of the shaft.

8. The electric motor according to claim 7, wherein an end portion of the stator fixing portion on the bottom portion side of the housing forms a surface of the bottom portion of the housing facing the outside.

9. The electric motor according to claim 7 or 8, wherein an end portion of the cylindrical portion on the bottom portion side of the housing forms a surface of the bottom portion of the housing facing the outside.

10. The electric motor according to claim 7, wherein the outer peripheral surface of the cylindrical portion is located radially apart from the inner peripheral surface of the cylindrical stator fixing portion by a prescribed gap.

11. The electric motor according to claim 7, wherein the outer peripheral surface of the cylindrical portion is separated from the inner peripheral surface of the cylindrical stator fixing portion by a prescribed interval in the radial direction.

12. The electric motor according to claim 10 or 11, wherein an annular space is provided which is surrounded by the outer peripheral surface of the cylindrical portion and the inner peripheral surface of the cylindrical stator fixing portion.

13. The electric motor according to claim 7, wherein a stepped portion is formed in an outer peripheral surface of the stator fixing portion, and an inner peripheral portion of a ring portion of the stator is fitted in the stepped portion.

14. The electric motor according to claim 7, wherein a mounting portion having the cylindrical portion is included.

15. The electric motor according to claim 7, wherein a mounting member fixed to the rotor is provided.

16. The electric motor according to claim 7, wherein a specific gravity of a member forming the shaft is smaller than a specific gravity of a member forming the bearings.

17. The electric motor according to claim 7, wherein the shaft is hollow.

18. The electric motor according to claim 7, wherein ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ In both end portions of the shaft, one end portion on the bottom side is located at a position closer to the inside of the case than the bottom.

19. The electric machine of claim 7, having: a rotor detachably fixed to the shaft.

20. A floating mobile body having the electric machine of claim 7.

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