A frameless motor precision assembly structure of a double-ended self-centering rotor

Abstract

The application discloses a frameless motor precision assembling structure of a double-end self-centering rotor, and relates to the technical field of frameless motors. The frameless motor precision assembling structure comprises a shell, one end of which is an open end, and the other end of which is inwardly contracted to form a ring part, and an extension part is integrally formed on the inner wall of the middle part of the shell; a stator is detachably embedded into the inside of the shell; a rotor is rotatably arranged in the middle through hole of the stator, and an air gap exists between the rotor and the stator, and a second bearing is arranged between the rotor and the extension part; an end cover is detachably mounted on the open end of the shell; and a hollow shaft assembly axially penetrates the rotor, the end cover and the shell, and is used for providing end centering for the rotor, and the whole is stable and reliable in operation.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of frameless motor, and particularly relates to a frameless motor precision assembly structure of a double-end self-centering rotor. BACKGROUND

[0002] With the continuous improvement of the performance requirements of industrial automation and precision manufacturing field on the motor, the frameless motor is widely used in robot joints, numerical control machine tool spindles and aerospace servo mechanisms and other scenes due to its compact structure, fast dynamic response and other advantages. However, the traditional frameless motor still faces certain technical bottlenecks in high precision and complex working condition adaptability.

[0003] The traditional frameless motor mostly adopts a single-end bearing support structure (such as a bearing arranged at only one end of the rotor), and its dynamic stability is highly dependent on the assembly precision. When bearing radial load, the single-end constraint architecture is easy to cause the rotor axis to deviate due to thermal deformation, assembly error or centrifugal effect, and then may cause local magnetic resistance unevenness, resulting in decreased electromagnetic coupling efficiency and increased vibration noise.

[0004] In addition, the axial pre-tightening of the frameless motor mostly depends on the static mechanical structure, and the pre-tightening force cannot be dynamically adjusted according to the working condition. When encountering load mutation, the traditional passive pre-tightening structure is easy to cause pre-tightening failure due to instantaneous torque overload.

[0005] Therefore, it is necessary to provide a frameless motor precision assembly structure of a double-end self-centering rotor to solve the above problems. SUMMARY

[0006] To solve the above problems, the present application provides the following technical scheme: a frameless motor precision assembly structure of a double-end self-centering rotor, comprising: an outer shell, one end of which is an open end, and the other end is inwardly contracted to form a ring part, and an extension part is integrally formed on the inner wall of the middle part of the outer shell; a stator which is detachably embedded into the inside of the outer shell; a rotor which is rotatably arranged in the middle through hole of the stator, and there is an air gap between the rotor and the stator, and a second bearing is arranged between the rotor and the extension part; an end cover which is detachably mounted on the open end of the outer shell; a hollow shaft assembly which axially penetrates the rotor, end cover and outer shell, and is used for providing end centering for the rotor.

[0007] As preferred, the hollow shaft assembly comprises: a first hollow shaft installed in the middle through hole of the rotor by interference fit; a second hollow shaft rotationally connected with the ring part of the housing, and the second hollow shaft is coaxially distributed with the first hollow shaft; an axial pre-tightening assembly connected between the first hollow shaft and the second hollow shaft, for realizing synchronous rotation transmission of the first hollow shaft and the second hollow shaft; the first hollow shaft is provided with axial pre-tightening force through the axial pre-tightening assembly; when the first hollow shaft bears abnormal torque, the increased axial pre-tightening force is generated through the deformation of the axial pre-tightening assembly.

[0008] As preferred, a first bearing is further arranged between the outer wall of the first hollow shaft and the inner wall of the end cover.

[0009] As preferred, two limiting rings are formed at the end of the second hollow shaft away from the axial pre-tightening assembly, and the two limiting rings are axially limitedly matched with the inner wall and the outer wall of the ring part of the housing.

[0010] As preferred, an inertia disc is coaxially fixed to the outer part of the second hollow shaft by interference fit or key connection.

[0011] As preferred, the axial pre-tightening assembly comprises: a pre-tightening ring coaxially fixed to the end face of the first hollow shaft close to the second hollow shaft; a plurality of force heads uniformly distributed in the circumferential direction, each of the force heads is a hemispherical structure and protrudes from the end face of the pre-tightening ring close to the second hollow shaft; a base ring coaxially fixed to the end face of the second hollow shaft close to the first hollow shaft; a plurality of force grooves corresponding to the force heads are arranged in the circumferential direction, each of the force grooves is arranged in the end face of the base ring close to the pre-tightening ring.

[0012] As preferred, the force grooves comprise two symmetrical half grooves, and the half grooves are arc-shaped or wedge-shaped.

[0013] As preferred, the spherical hardness of the force head is HRC58-62, the groove bottom of the force groove is provided with a wear-resistant coating, and the wear-resistant coating is a diamond-like carbon film with a thickness of 2-5 μm.

[0014] As preferred, a plurality of weight-reducing threaded holes are arranged on the inertia disc, and a weight-increasing column is selectively threadedly connected in the weight-reducing threaded hole.

[0015] Compared with the prior art, the present application provides a frameless motor precision assembly structure of a double-end self-centering rotor, which has the following beneficial effects: the double-end constraint is formed by the first bearing between the first hollow shaft and the end cover and the second bearing between the rotor and the extension part, the eccentric risk of single-end support is eliminated, the uniform and stable air gap between the rotor and the stator is realized by combining with the high-precision fitting tolerance, and the electromagnetic coupling loss and vibration noise are reduced.

[0016] The axial pre-tightening assembly in the application converts abnormal torque into increased axial pre-tightening force, cooperates with the low-pass filtering effect of the inertia disc, and avoids the risk of out-of-step or unbalanced load of the traditional structure under impact working conditions.

[0017] The inertia disc in the application realizes adjustable rotational inertia through the weight increasing column, and combines the high rigidity characteristics of the double-end self-centering structure, so as to customize the system inertia for different load characteristics, and disperse impact energy by double-end support. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 It is a front view structural schematic diagram of a frameless motor precision assembly structure of a double-end self-centering rotor.

[0019] Figure 2 It is a three-dimensional structural schematic diagram of a frameless motor precision assembly structure of a double-end self-centering rotor.

[0020] Figure 3 It is a sectional view structural schematic diagram of a frameless motor precision assembly structure of a double-end self-centering rotor.

[0021] Figure 4 It is a three-dimensional structural schematic diagram of an axial pre-tightening assembly in a frameless motor precision assembly structure of a double-end self-centering rotor.

[0022] In the figure: 1, housing; 2, end cover; 3, stator; 4, rotor; 5, first bearing; 6, second bearing; 7, axial pre-tightening assembly; 8, first hollow shaft; 9, second hollow shaft; 91, limiting ring; 10, inertia disc; 11, extension; 12, attachment cover; 71, pre-tightening ring; 72, force applying head; 73, base ring; 74, force applying groove. DETAILED DESCRIPTION

[0023] The terms "first", "second", etc. in the specification and claims of the present application and in the above description of the drawings are used to distinguish similar objects, and do not necessarily have to be used to describe a specific order or sequence. It should be understood that the terms thus used can be interchanged under appropriate circumstances, and this is merely a distinguishing way adopted in the description of the embodiments of the present application for the objects with the same attributes in the description. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, so that the processes, methods, systems, products or equipment containing a series of units do not have to be limited to those units, but can include other units not clearly listed or inherent to these processes, methods, products or equipment.

[0024] Embodiment: Please refer to Figures 1-4In the embodiment of the present application, a frameless motor precision assembly structure of a double-end self-centering rotor is provided, comprising: a shell 1, one end of which is an open end, and the other end is inwardly contracted to form a ring part, an extension part 11 is integrally formed on the inner wall of the middle part of the shell 1; a stator 3 which is detachably embedded into the inside of the shell 1; a rotor 4 which is rotatably arranged in the middle through hole of the stator 3, and there is an air gap between the rotor 4 and the stator 3, and a second bearing 6 is arranged between the rotor 4 and the extension part 11; an end cover 2 which is detachably mounted on the open end of the shell 1, and an attachment cover 12 can also be arranged between the end cover 2 and the shell 1 to maintain the appearance; a hollow shaft assembly which axially penetrates the rotor 4, the end cover 2 and the shell 1, and is used to provide end centering for the rotor 4.

[0025] The stator 3 generates a rotating magnetic field after being energized, driving the rotor 4 to rotate in the middle through hole of the stator 3. A small air gap is maintained between the rotor 4 and the stator 3 to ensure the electromagnetic coupling efficiency. The second bearing 6 is arranged between the end part of the rotor 4 and the extension part 11 of the shell 1 to provide radial support for the rotor 4.

[0026] In the embodiment, the hollow shaft assembly comprises: a first hollow shaft 8 which is installed in the middle through hole of the rotor 4 through interference fit; a second hollow shaft 9 which is rotatably connected with the ring part of the shell 1, and the second hollow shaft 9 and the first hollow shaft 8 are coaxially distributed; an axial pre-tightening assembly 7 which is connected between the first hollow shaft 8 and the second hollow shaft 9, and is used to realize synchronous rotation transmission of the first hollow shaft 8 and the second hollow shaft 9; the first hollow shaft 8 is provided with axial pre-tightening force through the axial pre-tightening assembly 7; when the first hollow shaft 8 bears abnormal torque, the axial pre-tightening force is increased through the deformation of the axial pre-tightening assembly 7.

[0027] The first hollow shaft 8 is rigidly connected with the rotor 4 through interference fit, ensuring that there is no relative rotation between the two.

[0028] In the embodiment, a first bearing 5 is further arranged between the outer wall of the first hollow shaft 8 and the inner wall of the end cover 2.

[0029] In the embodiment, two limit rings 91 which are spaced apart are formed on the end part of the second hollow shaft 9 away from the axial pre-tightening assembly 7, and the two limit rings 91 respectively form axial limiting cooperation with the inner wall and the outer wall of the ring part of the shell 1.

[0030] The two limit rings 91 on the end part of the second hollow shaft 9 respectively form axial limiting cooperation with the inner wall and the outer wall of the ring part of the shell 1, forming a "clamping type" limiting structure.

[0031] In addition, when the second hollow shaft 9 bears axial force, the inner limit ring 91 abuts against the inner wall of the ring part of the shell 1, and the outer limit ring 91 abuts against the outer wall of the ring part, forming a bidirectional mechanical stop, effectively eliminating the axial movement space.

[0032] The matching surface of the limit ring 91 and the ring part of the shell 1 is ensured to have a very small gap through precise machining (such as H7 / js6 matching tolerance), and the double-ring structure disperses the positioning error, so that the second hollow shaft 9 and the shell 1 maintain high concentricity, avoiding vibration or bearing eccentric wear caused by eccentricity.

[0033] In the embodiment, the outside of the second hollow shaft 9 is coaxially fixed with an inertia disc 10 through interference fit or key connection, and the inertia disc 10 is rigidly connected with the second hollow shaft 9 through interference fit or key connection, and the mass of the inertia disc 10 is concentrated outside the rotating radius, significantly increasing the rotational inertia of the system.

[0034] When the first hollow shaft 8 suddenly changes due to load, the inertia of the inertia disc 10 makes it maintain the original state, causing a transient speed difference between the second hollow shaft 9 and the first hollow shaft 8.

[0035] The speed difference drives the axial pre-tightening assembly 7 to deform, converting rotational kinetic energy into axial displacement, and further increasing the axial pre-tightening force on the first hollow shaft 8.

[0036] The rotational inertia of the inertia disc 10 forms a low-pass filtering effect, attenuating torque fluctuations when rotating at high speed, making the rotor 4 rotate more smoothly.

[0037] In the embodiment, the axial pre-tightening assembly 7 includes: a pre-tightening ring 71 coaxially fixed to the end face of the first hollow shaft 8 close to the second hollow shaft 9; a plurality of force heads 72 uniformly distributed in the circumferential direction, each of the force heads 72 being a hemispherical structure and protruding from the end face of the pre-tightening ring 71 close to the second hollow shaft 9; a base ring 73 coaxially fixed to the end face of the second hollow shaft 9 close to the first hollow shaft 8; and a plurality of force grooves 74 corresponding to the force heads 72 and opened in the circumferential direction, each of the force grooves 74 being opened in the end face of the base ring 73 close to the pre-tightening ring 71.

[0038] Further, the force grooves 74 include two symmetrical half grooves, and the half grooves are arc-shaped or wedge-shaped.

[0039] The pre-tightening ring 71 rotates synchronously with the first hollow shaft 8, and the hemispherical structure of the force head 72 is in contact with the force groove 74 of the base ring 73.

[0040] The arc-shaped / wedge-shaped structure of the force groove 74 transmits torque through surface contact, and when the first hollow shaft 8 suddenly changes due to load, the second hollow shaft 9 remains in the existing state due to the inertia of the inertia disc 10, causing the force head 72 to have a relative angular displacement with the force groove 74.

[0041] The arc-shaped or wedge-shaped half-groove converts the rotating motion into axial force: when the force head 72 slides along the slope, the normal reaction force increases, and the axial pre-tightening force is increased.

[0042] In this embodiment, the spherical hardness of the force head 72 is HRC58-62, and the groove bottom of the force groove 74 is provided with a wear-resistant coating, which is a diamond-like carbon film with a thickness of 2-5 μm, thereby prolonging the service life.

[0043] In this embodiment, a plurality of weight-reducing threaded holes are formed in the inertia disc 10, and a weight-increasing column is selectively threadedly connected in the weight-reducing threaded hole.

[0044] The inertia disc 10 is lightweightly designed through the weight-reducing threaded hole, and the weight-reducing threaded hole can be circumferentially symmetrically distributed (e.g. 12 equal parts), thereby ensuring uniform mass distribution.

[0045] The weight-increasing column (e.g. tungsten steel or brass material) is selectively installed in the weight-reducing threaded hole, and the rotational inertia is adjusted by changing the mass. For example, the inertia is increased by adding the weight-increasing column, and the load mutation is buffered by using kinetic energy.

[0046] The above is only a preferred specific embodiment of the present application, but the protection scope of the present application is not limited to this. Any person skilled in the art can make equivalent replacement or change according to the technical solution and the inventive concept of the present application within the technical range disclosed by the present application, which should be covered in the protection scope of the present application.

Claims

1. A precision assembly structure for a frameless motor with a double-ended self-centering rotor, characterized in that, include: The outer shell (1) has an open end at one end and a ring-shaped part at the other end that tapers inward. The inner wall of the middle part of the outer shell (1) has an extension (11) integrally formed. The stator (3) is detachably embedded inside the housing (1); The rotor (4) is rotatably disposed in the middle through hole of the stator (3), and there is an air gap between the rotor (4) and the stator (3). A second bearing (6) is disposed between the rotor (4) and the extension (11). End cap (2), which is detachably mounted to the open end of the housing (1); A hollow shaft assembly, which axially extends through the rotor (4), end cap (2) and housing (1), is used to provide end centering for the rotor (4); The hollow shaft assembly includes: The first hollow shaft (8) is installed in the middle through hole of the rotor (4) by interference fit; The second hollow shaft (9) is rotatably connected to the ring portion of the outer shell (1), and the second hollow shaft (9) and the first hollow shaft (8) are coaxially distributed. An axial preload assembly (7) is connected between the first hollow shaft (8) and the second hollow shaft (9) to achieve synchronous rotational transmission between the first hollow shaft (8) and the second hollow shaft (9); the axial preload assembly (7) provides axial preload force to the first hollow shaft (8); when the first hollow shaft (8) is subjected to abnormal torque, the deformation of the axial preload assembly (7) generates an increased axial preload force. The second hollow shaft (9) has two spaced limiting rings (91) at the end away from the axial preload assembly (7), and the two limiting rings (91) respectively form an axial limiting fit with the inner wall and outer wall of the ring portion of the outer shell (1); The inertial disk (10) is coaxially fixed to the outside of the second hollow shaft (9) by interference fit or key connection. The axial preload assembly (7) includes: A pre-tightening ring (71) is coaxially fixed to the end face of the first hollow shaft (8) near the second hollow shaft (9); The force-applying heads (72) are evenly distributed in the circumference. Each of the force-applying heads (72) is a hemispherical structure and protrudes from the end face of the pre-tightening ring (71) near the second hollow shaft (9). The base ring (73) is coaxially fixed to the end face of the second hollow shaft (9) near the first hollow shaft (8); The force application groove (74) is opened in the circumferential direction corresponding to the force application head (72), and each of the force application grooves (74) is opened on the end face of the base ring (73) near the pre-tightening ring (71).

2. The frameless motor precision assembly structure with a double-ended self-centering rotor according to claim 1, characterized in that, A first bearing (5) is also provided between the outer wall of the first hollow shaft (8) and the inner wall of the end cap (2).

3. The frameless motor precision assembly structure with a double-ended self-centering rotor according to claim 1, characterized in that, The force-applying groove (74) includes two symmetrically arranged semi-grooves, which are arc-shaped or wedge-shaped.

4. The frameless motor precision assembly structure with a double-ended self-centering rotor according to claim 1, characterized in that, The spherical hardness of the force-applying head (72) is HRC58-62, and the bottom of the force-applying groove (74) is provided with a wear-resistant coating, which is a diamond-like carbon film with a thickness of 2μm-5μm.

5. The frameless motor precision assembly structure with a double-ended self-centering rotor according to claim 1, characterized in that, The inertial disk (10) has multiple weight-reducing threaded holes, and the weight-increasing column is selectively connected to the threaded holes.

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