Motors and aircraft motors

Abstract

To provide a motor and an aircraft motor that can reduce manufacturing costs and have fewer restrictions on material selection. [Solution] The motor comprises a housing (3), a stator (22) arranged radially inside the housing (3), a rotor (21) arranged radially inside the stator (22) and rotating relative to the stator (22), an intervening member (6) inserted axially across the housing (3) and the stator (22) and opposing the circumferential shear force generated between the housing (3) and the stator (22), and a pressing member (7) fixed to the housing (3) and abutting against the stator (22) in the axial direction.

Description

[Technical Field]

[0001] The present invention relates to a motor and an aircraft motor. [Background technology]

[0002] Conventionally, shrink fitting or adhesive bonding has generally been used to fix the stator to the housing.

[0003] For example, in the rocket industry, robustness and thermal stability are required. Traditionally, shrink fitting has been widely used to secure motor stators used in the rocket industry as a means of withstanding strong vibration and impact environments and dissipating the heat generated by the motor itself. Shrink fitting is a technique in which one of the motor components (motor housing, motor stator, etc. (sometimes divided into a yoke and teeth)) is temporarily heated to a high temperature during the manufacturing process to expand the motor housing, and then other motor components (motor stator, etc.) are inserted into the motor housing, and then the housing is returned to room temperature, resulting in an interference that generates surface pressure and friction to secure the motor components.

[0004] However, shrink fitting and bonding have the drawback of being unreliable (in terms of heat resistance, oil resistance, impact resistance, etc.). To ensure reliability, shrink fitting may require auxiliary mechanical fastening, such as press-fitting the pins by performing machining (simultaneous machining of the housing and motor stator) after the shrink fitting is complete.

[0005] The manufacturing processes and man-hours required for these processes were a factor in ballooning product costs, so an alternative structure was sought to reduce costs. The lack of an alternative structure was one of the reasons why launch costs, which will be required in the future rocket market, could not be reduced (previously, shrink fitting was necessary because it was not possible to withstand strong vibrations and shocks and it was not possible to dissipate the heat generated by the motor, making it an essential technology for the success of rocket missions).

[0006] Furthermore, when the motor stator is divided into teeth and a yoke, the position of the teeth has traditionally been fixed by relying on adhesive strength, which also poses technical challenges (manufacturing variations, durability).

[0007] Furthermore, for example, when using in space, there are cases where it is desirable to use new materials such as CFRP to reduce weight, but materials that are weak to heat cannot be shrink fitted, so material selection is limited. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-306794 Summary of the Invention [Problem to be solved by the invention]

[0009] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a motor and an aircraft motor that can reduce manufacturing costs and have fewer restrictions on the selection of materials. [Means for solving the problem]

[0010] The motor of the present invention comprises a cylindrical housing, a stator arranged radially inside the housing, a rotor arranged radially inside the stator and rotating relative to the stator, an intervening member that is inserted axially to span the housing and the stator and resists circumferential shear forces that occur between the housing and the stator, and a pressing member that is fixed to the housing and abuts the stator directly or indirectly in the axial direction.

[0011] According to the present invention, the intervening member prevents the stator from shifting circumferentially relative to the housing, and the retaining member prevents the stator from shifting axially relative to the housing, so that the housing and stator can be firmly fixed together without using shrink fitting.

[0012] In addition, the motor of the present invention may be such that the housing has a housing side groove portion formed on its inner surface and extending in the axial direction, the stator has a stator side groove portion formed on its outer surface and extending in the axial direction, and the intervening member is a rod-shaped body that fits into the housing side groove portion and the stator side groove portion.

[0013] According to the above configuration, a general pin can be used as the interposing member.

[0014] In addition, the motor of the present invention may be configured so that the housing side groove portion is exposed on one end surface of the housing, the stator side groove portion is exposed on the end surface in the same direction as the housing, and the pressing member abuts directly or indirectly against the intervening member.

[0015] According to the above configuration, the grooves are exposed on the end faces of the housing and the stator during assembly of the motor, which facilitates the attachment of the interposing member. In addition, the retaining member prevents the interposing member itself from shifting in the axial direction.

[0016] In addition, the motor of the present invention may be configured so that the stator is composed of a combination of a yoke and teeth that are separate members from the yoke, and the pressing member abuts directly or indirectly against the yoke and the teeth in the axial direction.

[0017] According to the above configuration, even if the stator is configured to be divided into a yoke and teeth, the retaining member prevents the stator from shifting in the axial direction.

[0018] Furthermore, the motor of the present invention is an aircraft motor using the motor described above, wherein the stator is arranged in a clearance fit or intermediate fit relationship with respect to the housing, the abutment between the stator and the pressing member is a flat-to-flat abutment, and a material that promotes heat transfer may be interposed between the stator and the pressing member or between the stator and the housing.

[0019] According to the above configuration, a material that promotes heat transfer (TIM) is interposed between the stator and the retaining member or between the stator and the housing, thereby enabling effective heat dissipation between the stator and the retaining member or between the stator and the housing. [Effects of the Invention]

[0020] According to the present invention, the interposition member prevents the stator from shifting circumferentially relative to the housing, and the pressing member prevents the stator from shifting axially relative to the housing, so the housing and the stator can be firmly fixed together without using shrink fitting, thereby reducing manufacturing costs and providing a motor and an aircraft motor with fewer restrictions on material selection. [Brief explanation of the drawings]

[0021] [Figure 1] FIG. 2 is a front view of the motor of the present invention. [Figure 2] FIG. 2 is a cross-sectional view taken along line II-II in FIG. [Figure 3] FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2. [Figure 4] 10 is a cross-sectional view of the main part showing another configuration of the housing and the pressing member. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0022] An embodiment of a motor and an aircraft motor according to the present invention will be described with reference to the drawings.

[0023] As shown in FIGS. 1 and 2, the motor (aircraft motor) 1 includes a housing 3 for housing a motor unit 2 (see FIG. 2) that generates power. The housing 3 may be made of various metal composite materials, such as aluminum, aluminum alloy, titanium alloy, or magnesium alloy, to reduce weight. To further reduce weight, the housing 3 may be made of carbon fiber composite (CFRP). By incorporating a material that ensures electromagnetic compatibility with the carbon fiber composite (CFRP), it is possible to reduce noise emitted to the outside of the motor 1. Furthermore, if the housing 3 is made of two components, one of the various metal composite materials and the carbon fiber composite (CFRP), the heat from the stator 22 is dissipated to the outside through the metal parts of the housing 3 other than the parts made of carbon fiber composite (CFRP), because CFRP is a material that does not easily release heat. In the following description, the direction along the axis X of the rotating shaft 5 described later in FIG. 2 is the axial direction, the direction perpendicular to the axial direction (the up-down direction in FIG. 2) is the radial direction, and the right side of the axial direction in FIG. 2 is the front side, and the left side of the axial direction is the rear side.

[0024] 2, the housing 3 includes a cylindrical main body 31 with one axial end open, and a wall 32 disposed at the other axial end of the main body 31 for mounting a bearing 4 that rotatably supports a rotary shaft 5 (described later). One axial end of the housing 3 is closed by a pressing member 7 (described later).

[0025] 2 and 3, motor 1 is configured as an inner rotor type in which rotor 21 (described later) is attached to the radially inner side of stator 22 (described later) so as to rotate integrally with rotating shaft 5 (described later) which is rotatably supported approximately at the center of housing 3. Motor 1 of the present invention is particularly useful in the field of rockets, but may also be used as an actuator for aircraft and automobiles, as a drive source for actuators such as robots, as a drive source for pumps and compressors, as a flywheel power storage device, or for other purposes.

[0026] As shown in Fig. 2, the motor unit 2 includes a rotor 21 fitted onto the rotary shaft 5 so as to be rotatable integrally with the housing 3 around the axis X, and a stator 22 disposed radially inside the housing 3. In other words, the stator 22 is positioned radially outside the rotor 21. The rotor 21 has a plurality of permanent magnets (not shown) arranged along the circumferential direction. In this embodiment, a permanent magnet rotor is used, but any type of rotor may be used, such as a wound rotor or a squirrel-cage rotor for an induction machine.

[0027] 2 and 3, the stator 22 generates a magnetic force for rotating the rotor 21, and includes an annular yoke 221 that is clearance-fitted into the inner diameter side of the housing 3 (e.g., H7 / h7 in JIS fit symbols), a locking portion 222A that locks with a locked portion 221A of the yoke 221, a plurality of teeth 222 (nine in FIG. 3 ) that extend radially inward in the opposite direction to the locking portion 222A that extends radially outward, and coils 223 that are wound around each tooth 222. Because of the clearance fit, the outer diameter of the yoke 221 is smaller than the inner diameter of the housing 3. In this embodiment, the yoke 221 and the plurality of teeth 222 (nine in FIG. 3 ) are manufactured separately and then assembled, but the yoke 221 and the plurality of teeth 222 (nine in FIG. 3 ) may also be integrally formed.

[0028] A rod-shaped body (a cylindrical pin in this embodiment) 6 is fitted (press-fit) between the yoke 221 and the housing 3 as an intervening member to resist the circumferential shear force generated between the housing 3 and the stator 22 due to the rotation of the rotor 21 (JIS fitting symbol, for example, H7 / m6). A stator groove 221M extending axially over the entire outer circumferential surface of the yoke 221 is formed, and a housing groove 31M extending axially is formed on the inner circumferential surface of the main body 31 of the housing 3. The rod-shaped body 6 fits into these two grooves 221M, 31M. The stator groove 221M and the housing groove 31M have semicircular radial cross-sectional shapes and are configured to be approximately the same size. The inner diameter of the circle formed when the stator groove 221M and the housing groove 31M are joined (see FIG. 3) is set to be smaller than the outer diameter of the rod-shaped body 6. The axial length of the housing side groove portion 31M may be set according to the length of the rod-shaped body 6, as long as it is long enough to accommodate the rod-shaped body 6.

[0029] The housing groove 31M is exposed at the end face 31T on the open side (one side) of the main body 31 of the housing 3, and the stator groove 221M is exposed at the end face 221T of the yoke 221 facing the same direction as the housing 3. Therefore, when inserting the stator 22 into the housing 3 from the open side and loose-fitting it, the loose-fitting can be performed while visually checking from the open side that the stator groove 221M is aligned with the housing groove 31M. After loose-fitting, the yoke 221 can be fixed to the housing 3 by press-fitting the rod-shaped body 6. Furthermore, because the ends of the housing groove 31M and the stator groove 221M are exposed, it is easy to press-fit the rod-shaped body 6. The rod-shaped body 6 prevents the stator 22, including the yoke 221, from shifting circumferentially relative to the housing 3. Furthermore, since the housing groove 31M and the stator groove 221M can be formed in advance, machining is not required after fitting the stator 22 into the housing 3. Incidentally, when conventional shrink fitting is performed, the housing 3 and the stator 22 are deformed (thermal expansion / thermal contraction) due to the influence of temperature during shrink fitting. Therefore, if grooves for pin insertion are machined in the housing 3 and the stator 22 before shrink fitting, the grooves for pin insertion will be misaligned in the circumferential direction. Therefore, after shrink fitting, the housing 3 and the stator 22 need to be machined simultaneously, which is time-consuming.

[0030] As shown in Fig. 2, one axial end (front end) of the housing 3 is closed by a retaining member 7. This retaining member 7 includes an inner member 71 disposed axially inside and an outer member 72 disposed axially outside of the inner member 71. The retaining member 7 is a member that positions the stator 22 in the axial direction. This eliminates the need for shrink fitting as in the past. The axially inner side refers to the direction approaching the axial center, and the axially outer side refers to the direction away from the axial center.

[0031] The inner member 71 includes a flange portion 71A that protrudes radially inward and abuts against a rear end surface 8A of the bearing 8, which is the axially rearmost of the two bearings 8, 9 that rotatably support the rotary shaft 5; a cylindrical inner main body portion 71B that extends forward from the outer peripheral edge of the flange portion 71A and accommodates the bearing 8; and a rear cylindrical portion 71C that extends rearward from the outer peripheral edge of the inner main body portion 71B. Grooves 71M, 71N for accommodating waterproof O-rings 10, 11 are formed at two axial locations on the outer surface of the inner main body portion 71B. The rear O-ring 10 provides a seal between the inner surface 31A of the front end of the main body portion 31 of the housing 3 and the rear outer surface 71b of the inner main body portion 71B of the inner member 71, and the front O-ring 11 provides a seal between the inner surface 72a of a first cylindrical portion 72A (described later) of the outer member 72 and the front outer surface 71c of the inner main body portion 71B of the inner member 71. The inner peripheral edges of the two bearings 8 and 9 are fitted into an O-groove 5M formed on the outer surface of the front end of the rotary shaft 5.

[0032] The outer member 72 includes a first cylindrical portion 72A that covers the front side of the inner member 71 and is positioned opposite the front end surface 31B of the main body portion 31 of the housing 3, a first ring portion 72B that extends inward from the front end of the first cylindrical portion 72A, a second cylindrical portion 72C that extends forward from the inner end of the first ring portion 72B, and a second ring portion 72D that extends inward from the front end of the second cylindrical portion 72C. The first ring portion 72B, the second cylindrical portion 72C, and the second ring portion 72D accommodate a portion of the bearing 9 that is located axially frontward of the two bearings 8, 9.

[0033] A plurality of through holes 72K are formed at intervals in the circumferential direction on the outer peripheral edge of the outer member 72, and threaded holes 31N are formed in the front end of the main body 31 of the housing 3 to correspond to these through holes 72K (only one is shown in FIG. 2 ). When the outer member 72 is arranged to cover the front end of the inner member 71, the through holes 72K of the outer member 72 are aligned with the threaded holes 31N of the main body 31 of the housing 3, and six bolts 12 are threaded through the through holes 72K and into the threaded holes 31N, thereby fixing the outer member 72 to the housing 3. At this time, the inner member 71 indirectly contacts a front end surface 221T of the yoke 221 and a front end surface 6T of the rod-shaped body 6 via bearings 8 and 9 and presses them rearward via a TIM (time integral mechanism) described later. As a result, even though the stator 22 is configured to be divided into the yoke 221 and the teeth 222, the retaining member 7 prevents axial displacement of the stator 22. The abutment between stator 22 and retainer member 7 is flat-to-flat abutment. As described above, when stator 22 is divided into yoke 221 and teeth 222, shrink fitting can fix yoke 221, but the tightening force does not reach the teeth, resulting in an issue of not being able to fix them. In contrast, in the present invention, yoke 221 and teeth 222 can be firmly fixed by retainer member 7.

[0034] Heat dissipation can be improved by applying a thermal interface material (TIM) such as thermal compound, thermal grease, or thermally conductive sheet to gaps that are generated by loosely fitting the stator 22 into the housing 3, that is, to the inner surface 31C of the main body 31 of the housing 3 and the outer surface 221B of the yoke 221 of the stator 22, as well as to a contact portion 13 between the rear end surface of the yoke 221 of the stator 22 and the main body 31 of the housing 3, and a contact portion 14 between the yoke 221 of the stator 22 and the inner member 71. The TIM is a material that promotes heat transfer between the housing 3 and the stator 22 and between the stator 22 and the retainer member 7.

[0035] The heat dissipation paths are indicated by arrows in Figure 2. In Figure 2, heat transmitted to the yoke 221 is transferred from the outer surface 221B of the yoke 221 to the inner surface 31C of the main body 31 of the housing 3 via the TIM and dissipated. The heat transmitted to the yoke 221 is also transferred to the radially inner rear step 31D of the main body 31 of the housing 3 and the rear end surface 71d of the rear cylindrical portion 71C of the inner member 71 via the TIM and dissipated. The heat transmitted to the yoke 221 is also transferred to the main body 31 of the housing 3 via the rod-shaped body 6 and dissipated. Because many heat dissipation paths are formed in this way, heat dissipation efficiency can be improved. This motor is suitable for use in space, such as in motors used in rockets. The heat mass (heat capacity) of the entire motor 1 can also be increased.

[0036] The present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the spirit of the present invention.

[0037] In the above embodiment, the interposing member is configured as a cylindrical rod-shaped body 6, but it may be a polygonal pillar-shaped body or a pillar-shaped body having an irregular cross-sectional shape. The number of interposing members is not limited to one, and any number of interposing members, two or more, may be provided. Note that the shapes of the housing groove portion 31M and the stator groove portion 221M will also be changed in accordance with the change in the shape of the interposing member.

[0038] Furthermore, in the above embodiment, the pressing member 7 is fixed to the housing 3 with the bolts 12, but as shown in Fig. 4, a female threaded portion 31G may be formed on the inner surface of the main body 31 of the housing 3, and a male threaded portion 7G that screws into this female threaded portion 31G may be formed on the outer surface of the pressing member 7. Furthermore, in Fig. 2, the pressing member 7 is made up of two members, an outer member 72 and an inner member 71, but it may also be made up of a single member.

[0039] In addition, in the above embodiment, the yoke 221 is clearance-fitted to the inner diameter side of the housing 3, but the yoke 221 may be intermediate-fitted to the inner diameter side of the housing 3. If no TIM is used, interference fit may be used. [Explanation of symbols]

[0040] 1...motor, 2...motor portion, 3...housing, 4...bearing, 5...rotating shaft, 5M...O groove, 6...rod-shaped body (intervening member, pin), 6T...end face, 7...holding member, 7G...male thread portion, 8, 9...bearing, 8A...rear end face, 10, 11...O-ring, 12...bolt, 13, 14...contact portion, 21...rotor, 22...stator, 31...main body portion, 31A...inner surface, 31B...front end face, 31C...inner surface, 31D...step portion, 31G...female thread portion, 31M...housing side groove portion, 31N...screw hole, 31T...end face, 3 2...wall portion, 71...inner member, 71A...flange portion, 71B...inner main body portion, 71C...rear cylindrical portion, 71M, 71N...groove, 71b...outer surface, 71c...outer surface, 71d...end surface, 72...outer member, 72A...first cylindrical portion, 72B...first ring portion, 72C...second cylindrical portion, 72D...second ring portion, 72K...through hole, 72a...inner surface, 221...yoke, 221A...locked portion, 221B...outer surface, 221M...stator side groove portion, 221T...end surface, 222...teeth, 222A...locking portion, 223...coil, X...axis line

Claims

1. A cylindrical housing; a stator disposed radially inside the housing; a rotor disposed radially inside the stator and rotating relative to the stator; an interposition member that is inserted in the axial direction to span the housing and the stator and that resists a circumferential shear force generated between the housing and the stator; a pressing member fixed to the housing and in direct or indirect contact with the stator in the axial direction; A motor comprising:

2. the housing includes a housing side groove formed on an inner circumferential surface thereof and extending in the axial direction; the stator includes a stator groove formed on an outer peripheral surface thereof and extending in an axial direction; The motor according to claim 1 , wherein the intervening member is a rod-shaped member that fits into the housing groove and the stator groove.

3. The housing side groove portion is exposed on one end surface of the housing, the stator groove portion is exposed on the end surface facing the housing, The motor according to claim 2 , wherein the pressing member directly or indirectly abuts against the interposing member.

4. The stator is configured by a combination of a yoke and teeth that are separate members from the yoke, 4. The motor according to claim 1, wherein the pressing member directly or indirectly contacts the yoke and the teeth in the axial direction.

5. An aircraft motor using the motor according to any one of claims 1 to 3, the stator is disposed in a clearance or intermediate fit relationship with the housing; the abutment between the stator and the pressing member is flat-surface abutment, An aircraft motor, wherein a material that promotes heat transfer is interposed between the stator and the pressing member or between the stator and the housing.

Images