JP2015133821A - Direct drive motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a direct drive (DD) motor capable of achieving flat structure while minimizing footprints.SOLUTION: The DD motor includes: a motor part 2 for applying rotational torque to an output shaft S; a bearing 4 for rotatably supporting the output shaft; a rotation detector (resolver) 6 for detecting a rotation state of the motor part; and a housing 8 for positioning and fixing the motor part, the bearing and the rotation detector so as to align them in an output shaft direction against a motor placing surface B. The motor part is comprised of a stator 2a of an always static state and a rotor 2b rotatably arranged oppositely to the stator. The housing includes a motor housing (housing inner) 8a on which the stator is fixed and a motor rotor (rotor flange) 8b on which the rotor is fixed and has a double approximately cylindrical structure in which the motor housing and the motor rotor are coaxially arranged on different diameters and the housing inner and the rotor flange are integrally formed without generating gaps in an extension direction of the cylinders.

Description

  The present invention relates to a direct drive motor used in a positioning device such as an index table, for example, and relates to a motor structure in which a motor rotor and a motor housing are integrated.

  A direct drive motor (hereinafter referred to as a DD motor) directly transmits a rotational force to a rotating body without interposing a transmission mechanism such as a gear, a belt, and a roller, and the rotating body is transmitted to the rotated body. This is an electric motor that employs a drive system that rotates in a direction (motor load direct drive system), and various types are conventionally known depending on the application of the mounted machine (see Patent Document 1).

Such a DD motor includes a motor unit, a bearing for rotatably supporting the motor unit, and a rotation detector (resolver) for detecting the rotation state of the motor unit. It is a columnar structure. In order to reduce the size of the positioning device such as the index table, it is desirable that the installation space of the DD motor is as small as possible (space saving). For this purpose, the DD motor has a flatter structure (higher than the motor installation surface). It is desirable that the structure has a reduced thickness.
For example, as in the DD motor disclosed in Patent Document 1, a motor configuration in which a motor unit is arranged outside the bearing allows the DD motor to have a flat structure, and has a height from the motor installation surface. Can be suppressed.
On the other hand, in such a configuration, the outer diameter of the entire DD motor is increased by the amount of the motor portion arranged outside the bearing, and the installation area (so-called footprint) with respect to the motor installation surface is enlarged. For this reason, depending on the device, there may be a case where the required DD motor installation area cannot be secured sufficiently (in some cases, it is necessary to narrow the footprint). There is also a possibility that the motor configuration in which the motor unit is arranged cannot sufficiently cope.

  Therefore, various measures for improving the motor configuration have been taken in order to suppress the expansion of the DD motor footprint, and one example is that the motor part, bearings, and rotation detector (resolver) are arranged in the axial direction. Arranged motor configurations are known. FIG. 3 illustrates one configuration of such a DD motor (outer rotor type). In the DD motor, a motor unit 52, a bearing 54, and a rotation detector (resolver) 56 are provided on the installation surface (the same figure). Are arranged in this order in the axial direction (upward in the figure). By setting it as such a motor structure, it can suppress that the outer diameter dimension of the whole DD motor is expanded, and can suppress the expansion of a footprint.

In such a DD motor, the motor unit 52 includes a motor core (core and winding) 52a that is a stator and a rotor 52b that is a rotor. The motor core 52a is a motor housing ( The rotor (permanent magnet) 52b is fixed to the inner peripheral portion of a motor rotor (hereinafter referred to as rotor flange) 74 disposed on the motor outer peripheral side. A bearing (in FIG. 3, a four-point contact ball bearing) 54 is interposed between the housing inner 72 and the rotor flange 74, and the rotor flange 74 and the rotor 52b are brought together by the rotational torque generated by the motor unit 52. The housing inner 72 and the motor core 52a rotate. Each of the housing inner 72 and the rotor flange 74 has a divided structure that is divided into two parts with respect to the axial direction (vertical direction in FIG. 3), and the inner ring 54a of the bearing 54 is pivoted by the two housing inners 72a and 72b. The bearings 54 (inner and outer rings 54a and 54b) are positioned with respect to the housing inner 72 and the rotor flange 74 by sandwiching the outer ring 54b from the direction and sandwiching the outer ring 54b from the axial direction by the two rotor flanges 74a and 74b. In this state, the two housing inners 72a and 72b are fastened with the screws 76, and the two rotor flanges 74a and 74b are fastened with the screws 78, whereby the bearings 54 (inner and outer rings 54a and 54b) are connected to the housing inner 72 and It is positioned and fixed with respect to the rotor flange 74.

Further, the rotation detector (resolver) 56 detects the rotation state with high resolution so as to position the rotor flange 74 and thus the output shaft 90 while rotating with high accuracy. In this case, in order to detect the commutation timing of the motor current in the motor unit 52, two types of rotation detectors (resolvers) 56, that is, an absolute resolver 56a and an incremental resolver 56b are mounted, and these resolvers 56a and 56b are arranged in the axial direction. They are arranged in a column in the vertical direction in FIG.
The absolute resolver 56a includes an annular stator and a rotor (resolver stator core 92a and resolver rotor core 94a) that are opposed to each other at a predetermined interval, and the resolver stator core 92a is concentric with the axis C. The resolver rotor core 94a is attached to the housing inner 72a (the housing inner on the upper side in the axial direction in FIG. 3), whereas the resolver rotor core 94a has a rotor flange so that its inner circumference is eccentric with respect to the axis C. It is attached to 74a (in the figure, the rotor flange on the upper side in the axial direction). Therefore, when the resolver rotor core 94a rotates along with the rotation of the rotor flange 74a, the distance between the resolver stator core 92a is continuously changed in the circumferential direction, and the reluctance between the two is continuously changed depending on the position of the resolver rotor core 94a. Changes. At this time, the absolute resolver 56a (the resolver stator core 92a and the resolver rotor core 94a) outputs a unipolar resolver signal in which the fundamental wave component of the reluctance change is one cycle for each rotation of the resolver rotor core 94a. That is, the absolute resolver 56a is configured as a so-called ABS type monopolar resolver.

On the other hand, the incremental resolver 56b includes a ring-shaped stator and a rotor (resolver stator core 92b and resolver rotor core 94b) that are opposed to each other with a predetermined interval therebetween, both of which are concentric with the axis C. The resolver stator core 92b is attached to the housing inner 72a (in FIG. 3, the axially upper housing inner), and the resolver rotor core 94b is attached to the rotor flange 74a (in the same figure, axially upper rotor flange). . In the incremental resolver 56b, a plurality of salient pole-like teeth are formed at equal intervals in the circumferential direction on the resolver rotor core 94b, and the fundamental wave component of the reluctance change is a multi-cycle with respect to one rotation of the resolver rotor core 94b. A multipolar resolver signal is output. That is, the incremental resolver 56b is configured as a so-called INC type multipolar resolver.
As described above, the resolver 56 has a plurality of configurations of ABS type (absolute resolver 56a) and INC type (incremental resolver 56b), so that the rotation of the rotor flange 74 (specifically, the rotor flange 74a) and the output shaft 90 can be performed. It is possible to measure the state (for example, rotation speed, rotation direction or rotation angle) with higher accuracy.

  Of the two divided bodies of the housing inner 72 and the rotor flange 74, a divided body to which the resolver 56 (absolute resolver 56a and incremental resolver 56b) is attached (in FIG. 3, the housing inner 72a positioned on the upper side in the axial direction) The rotor flange 74a) is made of a nonmagnetic member so as not to hinder the measurement accuracy of the rotational state by the resolver 56.

JP 2003-299299 A

  In the DD motor configured as described above, the housing inner 72 and the rotor flange 74 are both divided as described above, and the divided housing inners 72a and 72b and the rotor flanges 74a and 74b are provided. It is necessary to position and fix the bearing 54 (inner and outer rings 54a and 54b) with respect to the housing inner 72 and the rotor flange 74 by fastening with screws 76 and 78, respectively. Therefore, the dimensions of the housing inner 72 and the rotor flange 74 in the axial direction must be ensured, resulting in an increase in height from the motor installation surface. When the fastening force by the screws 76 and 78 is insufficient, the split surfaces (contact surfaces) of the housing inners 72a and 72b and the split surfaces (contact surfaces) of the rotor flanges 74a and 74b are relatively displaced. There is also a risk of it.

  In addition, as described above, the DD motor is equipped with two types of rotation detectors (resolvers) 56, that is, an absolute resolver 56a and an incremental resolver 56b, both of which include a housing inner 72a and a rotor flange 74a. Are arranged in a column in the axial direction. Therefore, in order to attach these resolvers 56a and 56b, it is necessary to ensure the dimensions of the housing inner 72 and the rotor flange 74 in the axial direction, which further increases the height from the motor installation surface.

  As described above, in the configuration of the DD motor as shown in FIG. 3, there is a certain limit to the flat structure of the DD motor while suppressing the expansion of the footprint, and the expansion of the footprint and the flat structure of the DD motor are limited. Therefore, it is desired to realize a DD motor that can simultaneously reduce the space.

  The present invention has been made in order to solve such a problem, and an object of the present invention is to provide a DD motor (a motor rotor and motor housing integrated motor structure) that enables a flat structure while minimizing the footprint. It is to provide a DD motor.

In order to achieve such an object, a direct drive motor according to the present invention includes a motor unit that applies rotational torque to an output shaft, a bearing that rotatably supports the output shaft, A rotation detector for detecting a rotation state, and a housing for positioning and fixing the motor unit, the bearing, and the rotation detector so as to be aligned in the output shaft direction with respect to the motor installation surface are provided. In such a direct drive motor, the motor unit is composed of a stator that is always kept stationary, and a rotor that is rotatably arranged to face the stator, and the housing includes the stator. Has a motor housing to which the rotor is fixed and a motor rotor to which the rotor is fixed. The motor housing and the motor rotor have a double substantially cylindrical structure with different diameters arranged coaxially, and two pairs of rotation detection The stator and rotor are arranged in the radial direction, one is for absolute angle detection, the other is for relative angle detection, and both the motor housing and the motor rotor are relative to the extending direction of the cylinder. It is molded in one piece without any breaks.

  In this case, the bearing includes a pair of race rings arranged to face each other so as to be relatively rotatable, and a plurality of rolling elements incorporated so as to be able to roll between races formed on opposed surfaces of the race rings, One of the pair of track rings is fixed to the motor housing, and the other is fixed to the motor rotor. The motor housing is provided with a caulking portion on a cylindrical surface to which the one track ring is fixed. The motor rotor is provided with a caulking portion on a cylindrical surface to which the other race ring is fixed, and the pair of race rings are sandwiched between the caulking portion of the motor housing and the caulking portion of the motor rotor. In this state, the positioning and fixing may be performed with respect to the motor housing and the motor rotor.

  According to the DD motor according to the present invention, the motor rotor and motor housing integrated motor structure can minimize the footprint, and at the same time, the DD motor can have a flatter structure than before. The axial length can be kept small. As a result, it becomes possible to save the space of the DD motor as compared with the conventional case.

It is sectional drawing which shows the structure of the direct drive motor which concerns on one Embodiment of this invention. It is sectional drawing which shows the motor structure which positioned and fixed with respect to the housing (a housing inner and a rotor flange) in the state where the bearing was clamped by the caulking part. It is sectional drawing which shows the structure of the conventional direct drive motor.

Hereinafter, a direct drive motor (hereinafter also referred to as a DD motor) according to an embodiment of the present invention will be described with reference to the accompanying drawings. The DD motor according to the present invention can be used in a positioning device such as an index table.
FIG. 1 shows a configuration of a DD motor according to an embodiment of the present invention. Such a DD motor includes a motor unit 2 that applies rotational torque to the output shaft S, a bearing 4 that rotatably supports the output shaft S, and a rotation detector that detects the rotational state of the motor unit 2 ( The resolver 6, the motor unit 2, the bearing 4, and the rotation detector (resolver) 6 are positioned and fixed so that they are aligned with the motor installation surface B in the output shaft S direction (vertical direction in FIG. 1). A housing 8 is provided. In FIG. 1, the motor unit 2, the bearing 4, and the rotation detector (resolver) 6 are arranged in tandem in the output shaft S direction (upward in the figure) in this order with respect to the motor installation surface B. Although the configuration of the motor is shown as an example, the arrangement order is not particularly limited as long as these are positioned and fixed so as to be aligned with the motor installation surface B in the direction of the output shaft S.
That is, in the present embodiment, the motor unit 2, the bearing 4, and the rotation detector (resolver) 6 are arranged in tandem in the output shaft S direction with respect to the motor installation surface B, thereby minimizing the footprint of the DD motor. It is suppressed to.
In the following description, the side on which the motor installation surface B is positioned with respect to the direction of the motor axis C (the vertical direction in FIG. 1) is the installation surface side (the lower side in FIG. 1), and the installation surface The side opposite to the side (the connection side of the output shaft S) is called the output shaft side (the upper side in the figure).

The motor unit 2 includes a stator (stator) 2a that is always kept stationary, and a rotor (rotor) 2b that is disposed to face the stator 2a so as to be rotatable.
The stator (stator) 2a is provided with an electromagnet (motor core) 22 in which a plurality of teeth rows (not shown) are formed and a plurality of magnetic poles projecting inwardly in a rake shape are provided at equal intervals in the circumferential direction. The tooth rows of adjacent magnetic poles are arranged with a phase shift by a predetermined pitch. Each electromagnet (motor core) 22 is fixed with a stator coil 28 formed by winding wire 24 around a bobbin 26 (for example, joining with an adhesive or fastening with a fastening member).
On the other hand, the rotor (rotor) 2b has a cylindrical shape whose inner diameter is larger than the outer diameter of the stator (stator) 2a (that is, a cylindrical structure that is slightly larger than the stator 2a). ing.
The stator (stator) 2a and the rotor (rotor) 2b are arranged such that the stator 2a is arranged on the inner side with respect to the motor axis C than the rotor 2b and the electromagnet 22 of the stator 2a. The teeth of the rotor 2b are positioned so as to face each other with a slight gap. That is, the motor unit 2 is configured as a so-called outer rotor type.

The housing 8 includes a motor housing (hereinafter referred to as a housing inner) 8a to which a stator (stator) 2a of the motor unit 2 is fixed, and a motor rotor (hereinafter referred to as a rotor flange) 8b to which a rotor (rotor) 2b is fixed. The motor housing (housing inner) 8a and the motor rotor (rotor flange) 8b have a substantially cylindrical structure with double diameters arranged concentrically.
The housing inner 8a and the rotor flange 8b are both formed integrally with the cylinder extending direction (vertical direction in FIG. 1) without any break. That is, each of the housing inner 8a and the rotor flange 8b is formed in a substantially cylindrical shape that is continuous over the entire circumference from the end on the installation surface side to the end on the output shaft side with respect to the motor shaft center C direction. For example, unlike the motor configuration (the housing inner 72 and the rotor flange 74) shown in FIG. 3, it is not a divided structure that is divided into two with respect to the extending direction of the cylinder.

In the housing inner 8a, a stator fixing portion 80a is formed over the entire circumference in the vicinity of the installation surface side (in the vicinity of the lower end in FIG. 1) with respect to the direction of the motor axis C of the outer peripheral surface. The stator 2a of the motor unit 2 is fixed to the child fixing unit 80a. Further, the rotor flange 8b faces the stator fixing portion 80a of the housing inner 8a in the vicinity of the installation surface side (in the vicinity of the lower end in FIG. 1) with respect to the direction of the motor axis C on the inner peripheral surface. A rotor fixing portion 80b is formed over the entire circumference, and the rotor 2b of the motor unit 2 is fixed to the rotor fixing portion 80b. The width of the stator fixing portion 80a of the housing inner 8a and the rotor fixing portion 80b of the rotor flange 8b with respect to the motor axis C direction, the depth with respect to the radial direction, and the like are as follows. The size of 2b and the stator 2a
What is necessary is just to set arbitrarily according to the magnitude | size of the gap between the electromagnet 22 of this, and the tooth | gear of the said rotor 2b. Further, the fixing of the stator 2a to the stator fixing portion 80a and the fixing of the rotor 2b to the rotor fixing portion 80b are, for example, various methods such as fitting by press-fitting, bonding by an adhesive, and fastening by a fastening member. Alternatively, these methods may be combined.

The bearing 4 includes a pair of race rings 4a and 4b arranged to face each other so as to be relatively rotatable, and a plurality of rolling elements 4c incorporated so as to be able to roll between races formed on opposing surfaces of the race rings 4a and 4b. It has. In FIG. 1, an inner raceway (hereinafter referred to as an inner race) 4a is disposed on the motor shaft C side of the pair of raceways 4a and 4b, and an outer raceway (same as the above) 4b is arranged concentrically with the inner ring 4a. It is preferable that one bearing 4 is capable of applying both an axial load and a moment load. In the present embodiment, as shown in FIG. 1, balls that are rolling elements 4 c are inner and outer rings. The bearing 4 is configured as a four-point contact ball bearing that comes into contact with the four raceways 4a and 4b at two points each in total. The bearing is not limited to such a four-point contact ball bearing as long as both an axial load and a moment load can be applied. For example, a three-point contact ball bearing or a deep groove ball It is also possible to assume a bearing or a cross roller bearing. However, in the case of a cross roller bearing, it is desirable to use a general inner ring or outer ring that does not have a split structure, and that has an integral structure with the inner and outer rings.

  The bearing 4 is interposed between the motor housing (housing inner) 8a and the motor rotor (rotor flange) 8b (substantially cylindrical facing space between the two), and includes a pair of race rings (inner and outer rings) 4a and 4b. One of them (in this embodiment, the inner ring 4a) is fixed to the housing inner 8a, and the other (the same, the outer ring 4b) is fixed to the rotor flange 8b.

An inner ring fixing portion 82a is formed over the entire circumference of the housing inner 8a in the vicinity of the output shaft side of the stator fixing portion 80a with respect to the motor axis C direction of the outer peripheral surface. On the installation surface side, a protruding portion 84a that protrudes in the diameter-enlarging direction is provided over the entire circumference.
The inner ring 4a of the bearing 4 has an end surface on the installation surface side (the lower end surface in FIG. 1) abutted against the projecting portion 84a, and the inner circumferential surface thereof abutted against the inner ring fixing portion 82a. It is fixed (for example, bonded and fixed with an adhesive) to the fixing portion 82a. The rotor flange 8b has an outer ring fixing portion 82b in the vicinity of the output shaft side of the rotor fixing portion 80b with respect to the direction of the motor axis C on the inner peripheral surface so as to face the inner ring fixing portion 82a of the housing inner 8a. Is formed over the entire circumference, and on the output shaft side of the outer ring fixing portion 82b, a projecting portion 84b that projects in the diameter-reducing direction is provided over the entire circumference. The outer ring 4b of the bearing 4 is fixed to the outer ring so that the end surface on the output shaft side (the upper end surface in FIG. 1) is brought into contact with the protruding portion 84b and the outer peripheral surface thereof is brought into contact with the outer ring fixing portion 82b. It is fixed to the part 82b (for example, bonded and fixed with an adhesive). That is, the bearing 4 is positioned and fixed with respect to the housing inner 8a and the rotor flange 8b while being sandwiched between the protruding portion 84a of the housing inner 8a and the protruding portion 84b of the rotor flange 8b. Here, in FIG. 1, as an example, a protrusion 84a is provided on the installation surface side of the inner ring fixing portion 82a of the housing inner 8a, and a protrusion 84b is provided on the output shaft side of the outer ring fixing portion 82b of the rotor flange 8b. The bearing 4 is sandwiched between the projecting portions 84a and 84b. For example, the projecting portion is provided on the output shaft side of the inner ring fixing portion 82a of the housing inner 8a, and the outer ring fixing portion 82b of the rotor flange 8b is installed on the installation surface side. It is good also as a structure which provides a protrusion part in this and pinches the bearing 4 by these protrusion parts.

As described above, in the present embodiment, the inner ring 4a is bonded and fixed (adhered) to the inner ring fixing portion 82a of the housing inner 8a and the outer ring 4b is fixed to the outer ring fixing portion 82b of the rotor flange 8b by an adhesive. The rotational torque generated by the motor unit 2 can be directly transmitted to the output shaft S. Further, as described above, the housing inner 8a and the rotor flange 8b are both from the end on the installation surface side to the end on the output shaft side in the direction of the motor axis C (in FIG. 1, from the upper end to the lower end). For example, as shown in FIG. 3, the bearing 4 has a substantially cylindrical shape that is continuous over the entire circumference, such as a motor configuration (a configuration in which the housing inner 72 and the rotor flange 74 are both divided). When the (inner and outer rings 4a, 4b) are positioned and fixed with respect to the housing inner 8a and the rotor flange 8b, it is not necessary to fasten them with screws. Therefore, it is not necessary to secure the dimension for screw fastening in the direction of the motor axis C with respect to the housing inner 8a and the rotor flange 8b, and the height from the motor installation surface B of the DD motor is reduced accordingly. Can do. Furthermore, the relative displacement of components (for example, a split inner housing and a rotor flange) that can occur when the fastening force by screws is insufficient can be completely avoided.
The inner ring fixing part 82a of the housing inner 8a, the outer ring fixing part 82b of the rotor flange 8b, and the projecting parts 84a and 84b have a width dimension with respect to the motor axis C direction and a protruding height with respect to the radial direction. What is necessary is just to set arbitrarily according to the magnitude | size (bearing width) of 4a, 4b, the internal diameter dimension of the inner ring | wheel 4a, the outer diameter dimension of the outer ring | wheel 4b (bearing inner-outer diameter dimension), etc. Further, the inner ring 4a can be fixed to the inner ring fixing portion 82a and the outer ring 4b can be fixed to the outer ring fixing portion 82b by joining with an adhesive. Instead of or in addition to this, for example, fitting or fastening by press-fitting is performed. It can also be assumed to be performed by fastening with a member.

  Further, as shown in FIG. 2, a caulking portion 83a for preventing the inner ring 4a from falling off is provided on the cylindrical surface (inner ring fixing portion 82a) to which the inner ring 4a is fixed with respect to the housing inner 8a. A caulking portion 83b for preventing the outer ring 4b from falling off is provided on a cylindrical surface (outer ring fixing portion 82b) to which the outer ring 4b is fixed with respect to the rotor flange 8b, and the inner and outer rings 4a, 83b are formed by these caulking portions 83a and 83b. The bearing 4 may be positioned and fixed with respect to the housing inner 8a and the rotor flange 8b in a state where the 4b is sandwiched. Thus, the bearing 4 is held in the state in which the inner and outer rings 4a and 4b are clamped by the caulking parts 83a and 83b while the inner and outer rings 4a and 4b are sandwiched by the protrusions 84a and 84b of the housing inner 8a and the rotor flange 8b. It can be positioned and fixed to the flange 8b. For this reason, the bearing 4 can be positioned and fixed (fixed) more strongly with respect to the housing inner 8a and the rotor flange 8b, and even if a shocking external force is applied to the DD motor, the external force It is possible to sufficiently withstand the above and to prevent the bearing 4 from dropping (jumping out).

Only one rotation detector (resolver) 6 is positioned and fixed to the housing 8 (housing inner 8a and rotor flange 8b). In other words, in the present embodiment, the rotation detector (resolver) 6 is not a configuration that requires two types of absolute resolver 56a and incremental resolver 56b, as in the motor configuration shown in FIG. It has become.
The rotation detector (resolver) 6 includes a resolver stator core 6a, which is a stator having an annular shape, and a resolver rotor core 6b, which is a rotor. The resolver rotor core 6b is a motor. Concentric with the axis C, the resolver stator core 6a is attached to the housing inner 8a, while the resolver rotor core 6b is attached to the rotor flange 8b. At that time, the resolver stator core 6a is mounted with a space provided between the resolver stator core 6a and the housing inner 8a via a nonmagnetic mounting member 60a, and the resolver rotor core 6b is connected to the rotor via the nonmagnetic mounting member 60b. It is attached with a space provided between the flange 8b.
Since the resolver rotor and the resolver stator are arranged concentrically with the rotation detector, there is an advantage that the axial length can be shortened.

  Thus, by attaching the resolver stator core 6a and the resolver rotor core 6b to the housing inner 8a and the rotor flange 8b via the nonmagnetic attachment members 60a and 60b, the motor unit 2 with respect to the resolver stator core 6a and the resolver rotor core 6b. Can prevent magnetic sneaking from.

  A resolver stator fixing portion 86a is formed over the entire circumference of the housing inner 8a in the vicinity of the output shaft side (in the vicinity of the upper end in FIG. 1) with respect to the motor shaft center C direction of the outer peripheral surface. An attachment member 60a is fixed to the stator fixing portion 86a. The resolver stator core 6a is positioned and fixed with respect to the resolver stator fixing portion 86a by being attached to an attachment member 60a fixed to the resolver stator fixing portion 86a. Further, the rotor flange 8b has a resolver rotor fixing portion 86b in the vicinity of the output shaft side of the protruding portion 84b with respect to the direction of the motor axis C on the inner peripheral surface so as to face the resolver stator fixing portion 86a of the housing inner 8a. Is formed over the entire circumference, and the attachment member 60b is fixed to the resolver rotor fixing portion 86b. The resolver rotor core 6b is positioned and fixed with respect to the resolver rotor fixing portion 86b by being attached to an attachment member 60b fixed to the resolver rotor fixing portion 86b.

Further, the resolver stator core 6a is positioned and fixed to the resolver stator fixing portion 86a via the mounting member 60a in the housing inner 8a, and the resolver stator core 6a (specifically, a stator pole 62 described later) and the radial direction. A groove portion 88a is formed by recessing the portion directly facing to the concave shape in the reduced diameter direction over the entire circumference. Thereby, in a state where the resolver stator core 6a is positioned and fixed to the resolver stator fixing portion 86a via the attachment member 60a, a space by the groove portion 88a can be provided between the resolver stator core 6a and the housing inner 8a.
On the other hand, in the rotor flange 8b, in a state where the resolver rotor core 6b is positioned and fixed to the resolver rotor fixing portion 86b via the attachment member 60b, the diameter of the portion facing the resolver rotor core 6b in the radial direction is expanded over the entire circumference. A groove 88b that is recessed in a direction is formed. Thereby, in a state where the resolver rotor core 6b is positioned and fixed to the resolver rotor fixing portion 86b via the mounting member 60b, a space by the groove portion 88b can be provided between the resolver rotor core 6b and the rotor flange 8b.
It should be noted that the resolver stator core 6a and resolver rotor core 6b of the resolver 6 have the width dimension in the motor axis C direction and the depth in the radial direction of the resolver stator fixing portion 86a of the housing inner 8a and the resolver rotor fixing portion 86b of the rotor flange 8b. The size of the mounting members 60a and 60b and the size of the gap between the teeth of the resolver stator core 6a and the poles of the resolver rotor core 6b may be arbitrarily set. Further, the fixing of the mounting member 60a to the resolver stator fixing portion 86a, the fixing of the mounting member 60b to the resolver rotor fixing portion 86b, and the mounting of the resolver stator core 6a and the resolver rotor core 6b to these mounting members 60a and 60b are, for example, by press fitting. What is necessary is just to perform by various methods, such as fitting, joining by an adhesive agent, and fastening by a fastening member, or combining these methods.

Thus, the rotation detector (resolver) 6 is attached with the resolver stator core 6a provided with a space between the housing inner 8a via the attachment member 60a, and the resolver rotor core 6b via the attachment member 60b. A space is provided between the rotor flange 8b and the resolver stator core 6a and the resolver rotor core 6b are arranged to face each other with a slight gap. As a result, the resolver rotor core 6b can rotate with respect to the resolver stator core 6a that is always kept stationary.
The resolver stator core 6 a has a structure in which a plurality of stator poles 62 have an annular stratified iron core formed at equal intervals in the circumferential direction, and a resolver coil 64 is wound around each stator pole 62. On the other hand, the resolver rotor core 6b is composed of a hollow annular stratified iron core.

According to such a configuration, when the rotor flange 8b rotates together with the rotor (rotor) 2b with respect to the housing inner 8a and the stator (stator) 2a, the resolver rotor core 6b also rotates with this, and between the resolver stator core 6a. The reluctance of is continuously changed. By detecting the change in reluctance by the resolver stator core 6a, the position and angle of the resolver rotor core 6b (in other words, the rotor flange 8b and the output shaft S) can be detected.
Then, a resolver control circuit (not shown) converts the change in reluctance detected by the resolver stator core 6a into an electric signal (digital signal), and based on the electric signal, the position and angle of the resolver rotor core 6b per unit time. By calculating the fluctuation amount such as, the rotor flange 8b to which the resolver rotor core 6b is fixed, and the rotation state of the output shaft S connected to the rotor flange 8b (for example, the rotation speed, the rotation direction, or the rotation angle). Can be measured.

  In the present embodiment, the number of teeth of the resolver stator core 6a is matched with the number of pole pairs of the resolver rotor core 6b. This eliminates the need for an absolute resolver when detecting the commutation timing of the motor current, and mounts two types of rotation detectors (resolvers), an absolute resolver 56a and an incremental resolver 56b, as in the motor configuration shown in FIG. You don't have to. Therefore, it can be set as a single resolver structure, and suppression of the height from the motor installation surface B of a DD motor can be aimed at.

  As described above, according to the DD motor according to the present embodiment, the rotor housing 8b and the housing inner 8a have an integrated motor structure, so that the footprint can be minimized and the DD motor is conventionally used. Rather than a flat structure. As a result, it becomes possible to save the space of the DD motor as compared with the conventional case.

2 Motor part 2a Motor part stator 2b Motor part rotor 4 Bearing 6 Rotation detector (resolver)
8 Housing 8a Motor housing (housing inner)
8b Motor rotor (rotor flange)
B Motor installation surface S Output shaft

Claims (2)

A motor unit for applying rotational torque to the output shaft; a bearing for rotatably supporting the output shaft; a rotation detector for detecting a rotation state of the motor unit; and the motor unit, the bearing, and A direct drive motor having a housing for positioning and fixing the rotation detector so that the rotation detector is aligned with the motor installation surface in the output shaft direction;
The motor unit includes a stator that is always kept stationary, and a rotor that is rotatably disposed opposite the stator, and the housing is a motor housing to which the stator is fixed. And a motor rotor to which the rotor is fixed, and the motor housing and the motor rotor have a double substantially cylindrical structure with different diameters arranged coaxially,
The stator and rotor of two pairs of rotation detectors are arranged in a radial direction, one for absolute angle detection and the other for relative angle detection,
Both the motor housing and the motor rotor are formed integrally with the cylinder extending direction without a break. The bearing includes a pair of race rings arranged to face each other so as to be relatively rotatable, and a plurality of rolling elements incorporated so as to be able to roll between races formed on opposing surfaces of the race rings,
One of the pair of race rings is fixed to the motor housing, and the other is fixed to the motor rotor,
The motor housing is provided with a caulking portion on a cylindrical surface to which the one raceway ring is fixed,
The motor rotor is provided with a caulking portion on a cylindrical surface to which the other race ring is fixed,
2. The bearing is positioned and fixed with respect to the motor housing and the motor rotor in a state where the pair of race rings are held between the caulking portion of the motor housing and the caulking portion of the motor rotor. Direct drive motor described in 1.

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