JP4572591B2 - Rotation drive - Google Patents

Description

  The present invention relates to a rotary drive device that can rotatably support a rotary load on a rotary shaft and simultaneously apply a rotary drive force to the load.

  Conventionally, a rotary drive device that directly drives a load without using a speed reducer, that is, a direct drive motor is known and widely used. The direct drive motor generally includes an output shaft to which a rotating load is directly fixed, a bearing that rotatably supports the output shaft, a motor that drives the output shaft, and a resolver for detecting the rotational position of the motor. Therefore, it is used for a work rotation holding part of a machine tool, a drive joint part of a robot, and the like.

  As this direct drive motor, for example, a motor having a structure described in Patent Document 1 (Japanese Utility Model Publication No. 5-4751) is known. This direct drive motor is exemplified as an inner rotor type motor having a support structure that suppresses variation in the gap between the motor stator and the motor rotor.

  In such a direct drive motor, a disk-shaped cover that protects the winding portion forming the motor stator has been used. This cover is formed using a metal material, and is attached to the housing on the motor fixing side so as to cover the side surface in the axial direction of the motor.

In addition, in order to protect a coil | winding part and a motor sensor part, the structure which covers an insulating member on a coil | winding part is shown by patent document 2 (Unexamined-Japanese-Patent No. 2003-79090). Patent Document 3 discloses a structure in which an insulating member is provided inside the motor bracket to shorten the axial length, and a structure in which a rib is provided in the bracket and the rib is inserted between the coils to improve heat dissipation. (Japanese Patent Laid-Open No. 2000-228843).
Japanese Utility Model Publication No. 5-4751 JP 2003-79090 A JP 2000-228843 A

  However, the conventional protection structure for the winding portion, that is, the structure in which the metal cover is provided, is disadvantageous for reducing the size and weight of the entire motor.

  Specifically, when a metal cover is attached, it is necessary to set a required spatial distance between the winding portion and the cover in order to maintain insulation from the winding portion of the motor. By setting this spatial distance, the axial length of the entire motor is increased accordingly. In addition, when an external force is applied to the cover, the thickness of the cover must be reduced to prevent the cover from squeezing or contacting the winding and damaging the winding. It is necessary to make it thick and robust, and since the specific gravity of metal is large, an increase in size and an increase in weight are inevitable. Therefore, the reduction in size and weight of the entire motor has not been sufficient.

  The present invention has been made in view of the above-described problems, and protects the winding portion of the motor from external force to surely prevent damage to the winding portion and maintain insulation between wires, thereby improving reliability. At the same time, the object is to reduce the size and weight of the entire motor.

  In order to achieve the above-mentioned object, a rotary drive device according to the present invention includes a cylindrical fixed-side housing formed inside with a hollow portion extending in the axial direction, and a radial direction perpendicular to the axial direction of the fixed-side housing. A motor stator provided on the surface of the motor, and an output shaft for transmitting rotation to the motor and directly fixing a rotational load, the motor being fixed to the stationary housing, and the motor stator And a motor rotor that is rotatably arranged by a bearing through a predetermined amount of gap around the radial direction and is rigidly connected to the output shaft. The mounting portion located at one end of the motor in the axial direction is made of a resin material having substantially the same size as the side surface of the motor in the axial direction and having an insulating property and flame retardancy. A substantially annular cover is provided coaxially with the motor.

  According to the present invention, since the resin cover is provided at one end portion in the axial direction of the motor, the winding portion of the motor is protected from external force to prevent damage to the winding portion and insulation between the wires. Maintenance can be performed reliably, reliability can be improved, and the entire motor can be reduced in size and weight.

  Hereinafter, an embodiment of a direct drive motor as a rotary drive device according to the present invention will be described with reference to the drawings. The direct drive motor may be an outer rotor type or an inner rotor type, but the outer rotor type will be described in the following embodiments.

  As shown in FIG. 1, the direct drive motor 1 includes a housing 11 including an inner housing 11 </ b> A and an outer housing 11 </ b> B both formed in a substantially cylindrical shape, and an electric motor installed in a thick portion of the cylindrical housing 11. A motor (hereinafter simply referred to as “motor”) 12 and a resolver 13, a bearing 14 that rotatably supports the outer housing 11 </ b> B on the inner housing 11 </ b> A, and a cover 15 that is positioned on an axial side surface of the monitor 12 are provided. In FIG. 1, symbol BR is a hollow portion.

  Here, for explanation, an orthogonal coordinate system in which the axial direction of the housing 11 is the Z-axis direction is set as illustrated. For this reason, the radial direction of the housing 11 is a direction along the XY plane.

  Since the direct drive motor 1 according to the present embodiment is formed in the outer rotor type as described above, the inner housing 11A functions as a stationary housing, and the outer housing 11B rotates with the drive of the motor 12, and rotates. It functions as an output shaft directly connected to the object L. Note that the positional relationship between the fixing and the rotation may be opposite (that is, the inner rotor type).

  Hereinafter, the configuration of the direct drive motor 1 will be described in detail. The outer housing 11B is formed to have a larger diameter than the inner housing 11A, and is arranged coaxially. For this reason, as shown in FIG. 1, a space portion having a predetermined size and shape is formed between the walls of the housings 11B and 11A, and the motor 12, the resolver 13, and the bearing 14 described above are formed in this space portion. Is arranged.

  Among these, the bearing 14 is a rolling bearing capable of applying both a radial load and an axial load, and is interposed between the outer housing 11B and the inner housing 11A in the middle of the axial direction (Z-axis direction). Thus, the outer housing 11B is rotatably supported from the inner housing 11A via the bearing 14.

  The motor 12 is fixedly installed on the outer housing 11B so as to face a motor stator 12A fixedly installed on an inner housing 11A as a fixed-side housing, with a predetermined amount of gap (motor gap) GP from the motor stator 12A. Motor rotor 12B.

  Specifically, as shown in FIG. 1, a motor stator 12A is fixedly installed on a motor stator mounting surface P2 formed at a predetermined position on the outer surface of the inner housing 11A and closer to one end side in the axial direction than the bearing 14. ing. A motor rotor mounting surface P3 is formed at a position on the inner surface of the outer housing 11B so as to face the step surface P2. The motor rotor 12B is fixedly installed on the motor rotor mounting surface P3.

  The motor stator is formed by laminating electromagnetic copper plates, and has an annular base, a core 12A made of teeth projecting radially from the base, and an insulator (bobbin) 12D made of an insulator on each tooth. And a wound winding coil 12C. The motor stator is provided by fitting the base portion of the core 12A on the stator mounting surface P2 of the inner housing 11A. On the other hand, the motor rotor 12B is formed by arranging a plurality of permanent magnets along the circumferential direction on the motor rotor mounting surface P3 of the outer housing 11B so that the inner peripheral surfaces are alternately different in polarity.

  The resolver 13 described above is disposed at the position of the end portion in the axial direction opposite to the motor 12 of both the housings 11A and 11B. The resolver 13 includes a resolver stator 13A installed in the inner housing 11A, and a resolver rotor 13B installed in the outer housing 11B that faces the resolver stator 13A via a predetermined amount of gap. The resolver 13 outputs a signal in response to the rotational position of the motor 12, that is, the motor rotor 12A.

  The rotary load L described above is fixed to the resolver side surface (surface in the XY direction) of the outer housing 11B via a bolt as a fastening means. In FIG. 1, reference numeral 16 denotes a screw hole into which the bolt is screwed, and a plurality of them are arranged in the circumferential direction. For this reason, when the motor rotor 12B rotates with respect to the motor stator 12A, the outer housing 11B supported by the bearing 14 and functioning as the output shaft also rotates, so that the rotary load L also rotates eventually. The resolver 14 is configured as shown in, for example, Japanese Patent Laid-Open No. 6-46552. Further, each of the housings 11A and 11B does not necessarily have to be an integrally molded product along the axial direction, and is divided at a predetermined position in the axial direction (Z-axis direction) and rigidly connected to each other. It may be.

  Note that the positional relationship between the stator and the rotor is opposite to that in FIG. 1 for the inner rotor type.

  Next, the cover 15 according to the feature of the present invention will be described in detail with reference to FIGS. The cover 15 is mounted between the inner housing 11A and the outer housing 11B, which are stationary housings, in order to protect the winding portion of the motor stator 12A of the motor 12.

(Cover shape)
First, the shape of the cover 15 will be described. As shown in FIGS. 2 and 3, the cover 15 is a disc member formed in a donut shape (annular shape) having an outer diameter portion and an inner diameter portion. As will be described later, the cover 15 is made of a plastic material having insulating properties and flame retardancy.

  The cover 15 is continuously molded along the radial direction from the inner peripheral portion 15A through the central portion 15B to the outer peripheral portion 15C. Therefore, in the mounted state (see FIGS. 1 and 4), the inner peripheral portion 15A is locked to the inner housing 11A, the central portion 15B extends in the direction of the XY plane, and the outer peripheral portion 15C is in the outer housing 11B. It is designed to face the peripheral surface through a minute gap. The central portion 15B is opposed to the winding portion of the rotor stator 12A via a gap having a predetermined minute interval. That is, the cover 15 has an annular area substantially equal to the radial side surfaces of the motor stator 12A, the motor gap GP, and the motor rotor 12B, and can cover these side surfaces.

  More specifically, a plurality of claw members 21 are integrally formed on the inner peripheral portion (end) 15A of the cover 15 along the circumferential direction as shown in FIGS. Each of the claw members 21 is partly separated from the cover 15 by forming cuts parallel to the axial direction at both ends thereof, and has an oblique claw shape having a predetermined length in the circumferential direction and protruding in the radial direction. This is a protrusion. For this reason, each claw member 21 can be bent with a predetermined elasticity along the radial direction of the cover 15. It becomes easy to bend by making a cut. As will be described later, each claw member 21 is attached to the inner housing 11A by press-fitting.

  The direction in which the protrusion of each claw member 21 is inclined is set so as to be easily deformed when press-fitted in the press-fitting direction ID (see FIG. 4). Accordingly, the inner peripheral portion 15A of the cover 15 can be smoothly press-fitted along the outer peripheral surface of the inner housing 11A.

  The claw members 21 may be provided at predetermined intervals along the entire circumference of the inner peripheral portion 15A, but may be a partial range in the circumferential direction as in the present embodiment.

  Further, as shown in FIG. 2, at least one rotation stopper 22 is integrally formed on the inner peripheral portion 15 </ b> A of the cover 15. The rotation stopper 22 is a minute member protruding in the radial direction from the end surface of the inner peripheral portion 15A.

  On the other hand, the central portion 15B of the cover 15 forms an annular portion having a certain thickness, as can be seen from FIG. On the motor side (back side) of the central portion 15 in the mounted state, as shown in FIG. 2, at least one concentric rib 23 and a plurality of radial ribs 24 extending radially at equal intervals in the radial direction. Are formed integrally with the cover portion. Since the strength of the cover 15 is reinforced by the ribs 23 and 24, warping and twisting of the entire cover can be prevented during molding.

  The central portion 15B is integrated with the outer peripheral portion 15C. The outer peripheral portion 15C is formed thicker than the central portion 15B in order to increase the strength. In addition, the outer peripheral portion 15C is formed integrally with the central portion 15B while being inclined to the motor 12 side in the mounted state, and this outer peripheral portion 15C enters the radial end surface of the coil end when mounted. Yes. The surface of the outer peripheral portion 15C forms an inclined surface of, for example, approximately 45 degrees with respect to the axial direction. Thereby, the position of the opposing surface of 15 C of outer peripheral parts and the outer housing 11B can be located more leftward in FIG. As a result, the outer housing 11B can be shortened in the axial direction accordingly, the rotating portion can be reduced in weight, and the outer shape can be improved.

  Further, an insulator abutting portion 26 is formed on the outer peripheral portion 15C on the motor side surface at the time of mounting (see FIG. 4) to abut against the insulator 25 of the winding portion of the motor stator 11A. .

  The outer peripheral surface of the outer peripheral portion 15C is opposed to the inner peripheral surface of the outer housing 11B through a minute gap. The diameter of the facing portion is also larger than that of the motor gap GP. This is to prevent dust from entering the motor gap GP when the facing portion has the same diameter as the motor gap GP.

  In addition, since the outer peripheral part 15C and the outer housing 11B are comprised as mentioned above, the cover 15 is water from the surface (output shaft) located opposite to the surface (fixed surface) to which the motor 12 is attached. (Moisture) is prevented from entering.

(Cover material)
The above-described cover 15 is made of a plastic material. As the plastic material, it is desirable to use PBT (polybutylene terephthalate) or LCP (liquid crystal polymer) among thermoplastic plastics (crystalline thermoplastic plastics). The cover 15 is desirably formed as an injection molded product using such a plastic material. Since these resins are excellent in insulating properties, flame retardancy (heat resistance) and mechanical properties, they are widely used as motor insulating materials, and it is desirable to use them. Further, the cover 15 may be manufactured by machining instead of being manufactured as an injection molded product.

  Further, among thermoplastic plastics, so-called super engineering plastics excellent in temperature characteristics and mechanical characteristics can be used.

  There are mainly two types of gates provided in a mold for injection molding. One is a direct gate and the other is a submarine gate. In any case, since the cover 15 has a disk shape, an appropriate gate may be selected so as to prevent warping, bending, twisting and the like of the injection molded product. 3 and 4, reference numerals 27 and 28 denote a plurality of submarine gate positions that are protruding in the axial direction and direct gate positions that are formed at equal intervals on the entire circumference, respectively. The gate position is a position when the mold is filled with plastic resin.

(Fixing the cover)
The cover 15 formed as described above is fixed to the inner housing 11A on the fixed side using the claw member 21 formed integrally with the inner peripheral portion 15A.

  Specifically, as shown in FIG. 4, a minute recess is formed in the circumferential direction at the cover mounting position of the inner housing 11 </ b> A, thereby forming an annular groove 31. In addition, a notch (see reference numeral 40 in FIG. 6 described later) that engages with the rotation stopper 22 described above is formed at a predetermined position of the inner housing 11A.

  For this reason, the cover 15 is pushed in along the press-fitting direction ID so that the inner peripheral portion 15A of the cover 15 is fitted around the inner housing 11A. During the pushing, the plurality of claw members 21 of the inner peripheral portion 15A bend in the radial direction to allow such pushing. When each claw member 21 arrives at the annular groove 31, each bent claw member 21 extends in the radial direction and fits into the annular groove 31. Thereby, the cover 15 is locked and fixed to the inner housing 11A. At this time, the rotation stop 22 of the cover 15 is engaged with the notch 40 provided at the end of the inner housing 11, and the movement of the cover 15 in the circumferential direction is prohibited.

  On the other hand, when this fitting is completed, the insulator abutting portion 26 of the outer peripheral portion 15C of the cover 15 contacts the axial end surface of the coil end portion of the winding insulator 25 of the motor stator 12A. Thereby, the cover 15 is fixed at both ends of the inner peripheral portion 15A and the outer peripheral portion 15C, and the central portion 15B faces the winding portion of the motor stator 12A through a predetermined amount of gap. As a result, even when an external force is applied to the cover 15, the winding portion can be avoided from being pressed, and damage to the winding portion, insulation deterioration, and the like can be reliably prevented.

  Note that the abutting portion 26 of the outer peripheral portion 15C may abut against the axial end surface of the insulator 12D or the structure of the motor stator 12A.

  When the cover 15 is fixed, the plurality of claw members 21 are formed so as to be easily bent in the radial direction of the cover 15. Therefore, when the outer peripheral portion of the inner housing 11 </ b> A is fitted to the inner peripheral portion 15 </ b> A of the cover 15. Cover cracks can be prevented. On the other hand, since the shape of the claw member 21 is inclined as shown in FIG. 4, once it is attached, it cannot be easily removed.

  The annular groove 31 is concentric with the axial center of the motor 12. This annular groove 31 can be dealt with by lathe without milling.

(Variation related to fixing the cover)
The method for fixing the cover 15 is not limited to the above-described method, and may be performed as follows.

  The inner peripheral dimension of the cover 15 is set smaller than the outer diameter of the inner housing 11A, and press-fitting and shrink-fitting (the plastic material as the resin material used in the present embodiment can withstand heating at about 100 ° C. Yes).

  In addition, the inner housing 11A is provided with two or more notches similar to the notch 40 described later, while the cover 15 is provided with protrusions shaped to fit in the notches corresponding to these notches. May be perforated and bolted to a screw hole provided in the notch of the inner housing 11A (ie, the motor stator 12A). As a result, the cover 15 can be fixed more firmly without increasing the thickness of the inner housing. Furthermore, you may press-fit the end surface of the cover 15 in the radial direction end surface of the insulator of a motor winding (coil). Furthermore, a rod-shaped portion having a larger diameter than the through hole formed at the same position as the through hole of the cover 15 may be press-fitted into the through hole of the motor stator 12A having the lamination structure of the motor 12. It is good also as a shape which fits the inner surface 27 which cross | intersects the abutting part 26 of the cover 15 with the radial direction edge part of insulator 12D. Thereby, the cover 15 can be fixed in a more stable state.

  Since the direct drive motor 1 according to the present embodiment is configured as described above, it can exhibit various functions and effects.

  First, as long as the winding of the motor stator 12A is not crushed, the distance from the winding to the cover 15 can be reduced to the minimum, and can be minimized. Thereby, the total height of the motor 1 can be reduced.

  In addition, unlike conventional metal covers, there is no risk of insulation being lost due to contact or the like, and the reliability as a direct drive motor is enhanced. Further, in the case of the resin cover, the specific gravity of the material is significantly reduced in comparison with the motor structure using the metal cover, so that the motor itself is reduced in weight and the dynamic characteristics of the motor are improved.

  Furthermore, regarding the strength, the resin cover can exhibit performance equal to or higher than that of the metal cover. That is, when compared with the same plate thickness, the metal cover is stronger than the plastic cover, but the metal cover requires a considerable space on the side surface of the coil end as described above. In the case of a resin cover, such a useless space is reduced, so that the thickness can be increased. Therefore, even when the cover 15 is formed of a plastic material, the necessary strength of the entire cover can be sufficiently secured. it can.

  The cover 15 also has a function of preventing foreign matter from entering the motor gap GP with respect to the winding protection. For this reason, it is desirable that the cover 15 has a shape that covers from the winding portion of the motor stator 12A to the motor gap GP.

  Furthermore, since the outer shape of the outer peripheral portion 15C of the cover 15 is formed on an inclined surface, the axial dimension of the rotor flange (that is, the outer housing 11B) can be shortened as compared with the conventional case. Thereby, the weight of the whole motor and a rotor inertia can also be reduced.

  Here, the effect of this embodiment is demonstrated in contrast with the conventional metal cover. When the metal cover is attached to the motor rotor, the metal plate rotates beside the coil end portion of the winding. If this metal cover can be in contact with the wiring material of the winding part, the possibility of motor failure is great. For this reason, in the case where the cover for protecting the winding is attached to the motor rotor portion, the distance between the winding portion and the cover needs to have a sufficient margin. For this reason, since it is necessary to set such a large distance, in the case of a metal cover, the height of the motor (the length in the axial direction) is increased, which is a major obstacle to downsizing. Also, attaching a metal cover to the motor rotor increases the rotational inertial force of the rotor, so that the motor dynamic characteristics (responsiveness) are not good. However, as in the present embodiment, the resin cover 15 is provided on the inner housing 11A (fixed housing), that is, the motor stator 12A side, so that the above-described obstruction factors for downsizing can be eliminated and downsizing can be achieved. In addition, the dynamic characteristics of the motor can be improved.

  Further, in the case of a metal cover, if this cover is displaced, insulation from the windings cannot be maintained, which may lead to motor failure. In order to prevent this, it is required to firmly fix the metal cover. Specifically, a screw tap is cut on the motor housing, the rotor flange, etc., and fixed with fastening means such as bolts and screws. It was. Further, in order to cut the tap for the cover, it was sometimes performed separately by milling. For example, a case where a plane perpendicular to the axial direction is formed separately from the mounting of the motor and the output end face. In other words, tapping, drilling, milling, and the like are necessary only for fixing the cover, and this has been a cause of increased manufacturing costs. However, according to the present embodiment, the resin cover 15 can be easily and surely held by the engagement between the claw member and the annular groove and the abutting structure of the insulator, and the manufacturing surface when the conventional metal cover is provided. Inconveniences from can also be avoided reliably.

  5 shows an overview of the direct drive motor 1 viewed from the axial direction.

  As shown in FIG. 1, the wiring cable 41 for the resolver 13 passes through a through hole that passes through the inner housing 11 </ b> A in the axial direction (Z-axis direction) via a notch provided at the resolver side end of the inner housing 11 </ b> A. Then, it is pulled out from the notch 40 of the inner housing 11A. The notch 40 engages with the rotation stop 22 of the cover 15 described above and prohibits rotation in the rotational direction. However, since the notch 40 is formed to be large, the gap 40 is used to apply the notch. The wiring cable 41 is pulled out. The wiring cable 43 with respect to the motor stator 12A is similarly pulled out. Thereby, wiring can be performed more easily.

In addition, this invention is not limited to the thing of embodiment mentioned above, It can implement with a various form further within the range of the summary as described in a claim.
For example, the resin cover may be fixed to the outer housing. In that case, a groove for fitting the resin cover may be provided on the inner peripheral surface of the outer housing, and an engaging claw provided on the outer peripheral surface of the resin cover may be engaged with the groove.

  Moreover, although the rotation drive device which an outer housing rotates is shown, it is applicable also to what an inner housing rotates.

  Further, the cover of the present invention can be applied to both the configuration in which the motor 12 is provided at the end portion on the rotational load mounting surface side and the configuration in which the cover of the present invention is provided. In this case, it is preferable to form an umbrella shape so that the cover does not serve as a water tray, and the outer peripheral surface protrudes outward from the outer peripheral surface of the outer housing.

It is an axial sectional view of a direct drive motor concerning one embodiment of the present invention. It is a perspective view which shows the back surface of the cover used by embodiment. It is a perspective view which shows the surface of the cover used by embodiment. It is a fragmentary sectional view of the radial direction which shows the fixed state of a cover. It is an external view which shows the end surface of the axial direction of the direct drive motor which concerns on FIG.

Explanation of symbols

1 Direct drive motor (rotary drive device)
11 Housing 11A Inner housing (fixed side housing)
11B Outer housing (output shaft)
12 Motor 12A Motor stator 12B Motor rotor 13 Resolver 14 Bearing 15 Cover (resin cover)
15A Inner peripheral part 15B Central part 15C Outer peripheral part 21 Claw member 22 Anti-rotation 23, 24 Rib 25 Insulator 26 Insulator pressing part 31 Annular groove 40 Notch part GP Motor gap L Rotating load

Claims (3)

A cylindrical fixed-side housing extending in the axial direction, a motor provided on a radial surface orthogonal to the axial direction of the fixed-side housing, and rotationally driven by the motor, and a rotational load is directly fixed. An output shaft,
A motor stator that is fixed to the stationary housing, and a motor rotor that is rotatably arranged by a bearing through a predetermined amount of gap around the radial direction of the motor stator and rigidly connected to the output shaft the rotary drive apparatus configured with bets,
The mounting portion located at one end of the motor in the axial direction is made of a resin material having substantially the same size as the side surface of the motor in the axial direction and having an insulating property and flame retardancy. A substantially annular cover is provided coaxially with the motor,
The cover is attached to one axial end portion of the fixed housing and the output shaft, and the cover has a minute surface and the same surface of the other axial end portion of the fixed housing and the output shaft. A rotation drive device characterized by being opposed in the radial direction through a gap . The cover is formed with a pawl that can be bent at a circumferential end on the radially inner side, and a latching portion that can be latched on the pawl on a circumferential surface on the radially outer side of the housing. The rotary drive device according to claim 1, wherein 3. The rotation according to claim 1, wherein an abutting portion that abuts against a structure portion excluding the winding portion of the stator is formed at a circumferential end portion of the cover on a radially outer side. Drive device.

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