A frameless motor turntable with load isolation and taper surface self-centering docking

Abstract

This invention discloses a frameless motor turntable with load isolation and conical self-centering docking, relating to the field of high-precision servo drive technology. It includes: a turntable base on which a stator housing is fixed; a power input shaft system including a rotor shaft, a frameless motor, and a first shaft bearing pair, the frameless motor and the first shaft bearing pair being disposed between the rotor shaft and the stator housing; and a load output shaft system including a drive shaft and a second shaft bearing, the drive shaft being coaxially disposed within the turntable base, and the second shaft bearing being disposed between the drive shaft and the turntable base. The rotor shaft and drive shaft are coaxially connected, and their contact surfaces are mutually fitted convex and concave conical surfaces. The rotor shaft is a hollow structure with an annular axial vibration damping stress groove near the convex conical surface on its inner wall. This invention reduces the impact of external loads on the air gap of the frameless motor and the drive bearings through separate support of the load shaft system and drive shaft system, parallel anchoring of the base, and conical self-centering locking.

Description

Technical Field

[0001] This invention relates to the field of high-precision servo drive technology, and in particular to a frameless motor turntable with load isolation and conical self-centering docking. Background Technology

[0002] With the increasing demands for dynamic response speed and positioning accuracy in high-end equipment such as aerospace optoelectronic pods, airborne radar antenna mounts, high-precision gimbals, and semiconductor wafer transmission equipment, frameless torque motors have been widely used in precision turntable systems due to their small size, high torque density, and zero backlash. These turntables typically need to bear large inertial loads and withstand external disturbances such as wind loads, centrifugal forces, or gravitational torques during operation, thus placing high demands on the shaft bearing path, motor air gap stability, and assembly coaxiality.

[0003] Existing frameless motor turntables mostly employ a structure where the load spindle is directly connected to or highly coupled with the motor rotor. External loads are easily transmitted to the motor rotor or drive bearings via the drive shaft, causing a shift in the small electromagnetic air gap between the frameless motor's stator and rotor, thus affecting torque stability and service life. Even though some direct-drive turntables employ symmetrical support, conical positioning, or thermal deformation compensation structures, their focus is usually on motor mounting and positioning or thermal error control, making it difficult to simultaneously solve the problems of independent load unloading, coaxial positioning after locking the separate shaft system, and the release of parasitic stresses caused by multi-bearing static indeterminate stresses. Therefore, it is necessary to provide a frameless motor turntable with a clearly defined structural relationship, ease of manufacture, and the ability to reduce the impact of external loads on the motor air gap. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a frameless motor turntable with load isolation and conical self-centering docking, which solves the technical problems of external loads easily affecting the motor air gap, difficulty in ensuring the coaxiality of the split shaft system assembly, and the potential for parasitic stress in multi-bearing supports in existing frameless motor turntables.

[0005] To achieve the above objectives, the present invention is implemented using the following technical solution:

[0006] In a first aspect, the present invention provides a frameless motor turntable with load isolation and self-centering conical docking, comprising:

[0007] The turntable base has a stator housing fixed on its mounting surface;

[0008] The power input shaft system includes a rotor shaft, a frameless motor, and a first shaft bearing pair. The rotor shaft is coaxially disposed within the stator housing, and the frameless motor and the first shaft bearing pair are disposed between the rotor shaft and the stator housing.

[0009] The load output shaft system includes a drive shaft and a second shaft bearing. The drive shaft is coaxially disposed within the turntable base, and the second shaft bearing is disposed between the drive shaft and the turntable base.

[0010] The rotor shaft and the transmission shaft are coaxially connected, and the contact end faces of the rotor shaft and the transmission shaft are mutually fitted convex and concave conical surfaces; the rotor shaft is a hollow structure and the inner wall is provided with an annular axial vibration damping stress groove near the convex conical surface.

[0011] Optionally, the frameless motor includes a rotor and a stator that are configured to cooperate with each other, the rotor being fixed to the outer wall of the rotor shaft, and the stator being fixed to the inner wall of the stator housing.

[0012] Optionally, the first shaft bearing pair includes a first drive bearing and a second drive bearing symmetrically arranged on both sides of the frameless motor, used to constrain the radial runout and axial runout of the rotor shaft, so as to maintain the electromagnetic air gap between the rotor and stator of the frameless motor.

[0013] Optionally, the first drive bearing is positioned close to the convex conical surface, and the axial projection of the annular axial damping stress groove partially overlaps with the inner ring mounting position of the first drive bearing.

[0014] Optionally, the second shaft bearing is a single rigid high-load bearing, which is a crossed roller bearing or a double-row angular contact ball bearing.

[0015] Optionally, the output end face of the rotor shaft is a convex conical surface, and the input end face of the transmission shaft is a concave conical surface, wherein the semi-cone angle between the convex and concave conical surfaces is... Satisfy the constraints:

[0016]

[0017] In the formula, The coefficient of static friction between the materials in contact with the convex and concave conical surfaces. This is the incremental angle of the slight slip.

[0018] Optionally, the rotor shaft and its convex conical surface are integrally machined, and the drive shaft and its concave conical surface are integrally machined.

[0019] Optionally, the annular axial vibration damping stress groove is formed by locally thinning the wall thickness of the rotor shaft, and both sides of the annular axial vibration damping stress groove are arc-shaped transition surfaces.

[0020] Compared with the prior art, the beneficial effects achieved by the present invention are as follows:

[0021] The present invention provides a frameless motor turntable with load isolation and self-centering conical surface docking, which has the following technical features:

[0022] Load and error isolation: The stator housing and the second shaft bearing are fixed in parallel on the same turntable base. External radial loads and axial overturning moments are transmitted to the turntable base via the drive shaft and the second shaft bearing, reducing the possibility of such loads acting directly on the rotor shaft and drive bearings. This helps maintain the air gap stability of the frameless motor and reduce torque fluctuations.

[0023] Standardized datum and assembly accuracy: The load-bearing inner hole of the turntable base and the stator housing mounting surface can be machined and inspected around the same central axis, so that the load shaft system and the drive shaft system have a unified assembly datum.

[0024] Conical self-centering and stress relief: The first and second positioning cones generate radial centering under axial preload, which facilitates coaxial positioning when locking the split shaft system; the annular axial vibration damping stress groove provides limited elastic clearance for the docking interface, which helps to reduce parasitic stress under multi-bearing support conditions. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of a frameless motor turntable with load isolation and self-centering conical docking provided by an embodiment of the present invention;

[0026] Figure 2 This is a schematic diagram of the structure of the convex conical surface and the concave conical surface provided in the embodiment of the present invention;

[0027] The diagram is marked as follows:

[0028] 1. Turntable base; 11. Stator housing;

[0029] 2. Power input shaft system; 21. Rotor shaft; 22. Frameless motor; 23. First shaft bearing pair; 231. First drive bearing; 232. Second drive bearing; 24. Conical surface; 25. Annular axial vibration damping stress groove;

[0030] 3. Load output shaft system; 31. Drive shaft; 32. Second shaft bearing; 33. Concave conical surface. Detailed Implementation

[0031] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0032] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are used only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0033] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0034] Example 1

[0035] like Figure 1 and Figure 2 As shown, this embodiment of the invention provides a frameless motor turntable with load isolation and conical self-centering docking, including a turntable base 1, a power input shaft system 2, and a load output shaft system 3; the frameless motor turntable is integrally mounted on the turntable base 1, and the turntable base 1 serves as the common bearing reference and assembly reference for the power input shaft system 2 and the load output shaft system 3.

[0036] A stator housing 11 is fixed on the mounting surface of the turntable base 1. The turntable base 1 is hollow in the middle for subsequent installation of the second shaft bearing 32. The stator housing 11 and the second shaft bearing 32 are arranged coaxially. The stator housing 11 is an independent component and is locked to the mounting surface of the turntable base 1 by multiple base bolts. The outer ring of the second shaft bearing 32 is fixed inside the turntable base 1 by radial interference fit.

[0037] The power input shaft system 2 includes a rotor shaft 21, a frameless motor 22, and a first shaft bearing pair 23. The rotor shaft 21 is coaxially disposed within the stator housing 11, and the frameless motor 22 and the first shaft bearing pair 23 are disposed between the rotor shaft 21 and the stator housing 11. The frameless motor 22 includes a rotor and a stator that are mutually fitted together. The rotor is fixed to the outer wall of the rotor shaft 21, and the stator is fixed to the inner wall of the stator housing 11. The first shaft bearing pair 23 includes a first drive bearing 231 and a second drive bearing 232 symmetrically disposed on both sides of the frameless motor 22. The inner rings of the first drive bearing 231 and the second drive bearing 232 are fixed to the outer wall of the rotor shaft 21, and the outer rings are fixed to the inner wall of the stator housing 11, which are used to constrain the radial and axial runout of the rotor shaft 21 to maintain the electromagnetic air gap between the rotor and the stator of the frameless motor 22.

[0038] The load output shaft system 3 includes a drive shaft 31 and a second shaft bearing 32. The drive shaft 31 is coaxially mounted within the turntable base 1, and the second shaft bearing 32 is positioned between the drive shaft 31 and the turntable base 1. In this embodiment, the second shaft bearing 32 is a single rigid high-load bearing, which is either a high-rigidity crossed roller bearing or a double-row angular contact ball bearing capable of simultaneously bearing axial force, radial force, and overturning moment. The inner ring of the second shaft bearing 32 supports the drive shaft 31, so that the external radial load and axial overturning moment applied to the drive shaft 31 are transmitted to the turntable base 1 via the second shaft bearing 32.

[0039] The rotor shaft 21 and the transmission shaft 31 are coaxially connected, and the contact end faces of the rotor shaft 21 and the transmission shaft 31 are mutually fitted with a convex conical surface 24 and a concave conical surface 33; the convex conical surface 24 and the concave conical surface 33 are fitted and locked together to achieve power transmission and coaxial positioning in the state of separate support of the power input shaft system 2 and the load output shaft system 3; the rotor shaft 21 is a hollow structure and the inner wall is provided with an annular axial vibration damping stress groove 25 near the convex conical surface 24.

[0040] When an external load generates radial impact or axial overturning moment, the load is transmitted to the second shaft bearing 32 via the drive shaft 31, and then unloaded onto the turntable base 1 by the second shaft bearing 32. Since the drive shaft 31 and the rotor shaft 21 are separated from each other on the bearing support, the external load is not directly borne by the first drive bearing 231 and the second drive bearing 232, thereby reducing the impact of the external load on the air gap stability of the frameless motor 22.

[0041] Since the drive side and load side are supported separately, a mechanical self-centering docking mechanism is provided in this invention to achieve coaxial positioning after locking and docking. The output end face of the rotor shaft 21 is an integrally formed convex conical surface 24, and the input end of the transmission shaft 31 is an integrally formed concave conical surface 33. The semi-cone angles of the convex conical surface 24 and the concave conical surface 33 are... Satisfy the constraints:

[0042]

[0043] In the formula, The coefficient of static friction between the contacting materials of the convex conical surface 24 and the concave conical surface 33. This is the incremental angle of the slight slip. The angle is 1° to 3°. This angle relationship makes the half-cone angle of the conical pair slightly larger than the self-locking critical angle, which is beneficial for the sliding alignment when the bolt is tightened and facilitates disassembly and maintenance later.

[0044] During assembly, circumferentially distributed fastening bolts pass through the drive shaft 31 and are locked onto the rotor shaft 21. As the fastening bolts gradually apply an axial preload Fa, the convex conical surface 24 undergoes a slight axial slip along the concave conical surface 33. Due to the inclined guiding effect of the conical surface, this axial preload Fa is converted into a radial centering force Fr distributed around the axis of rotation on the contact surface.

[0045]

[0046] The radial centering force Fr causes the geometric center line of the drive shaft 31 to approach the rotation axis of the rotor shaft 21, thereby compensating for the radial deviation caused by the separation and assembly of the two shaft systems. After assembly, the two shaft systems are kept coaxially positioned by tapered surface fitting and axial fastening bolts.

[0047] Because the system includes a first drive bearing 231, a second drive bearing 232, and a second shaft bearing 32, multiple points of support may be formed after assembly and locking. To reduce the additional bearing load caused by minor machining errors or installation eccentricity of the turntable base 1, this invention introduces a parasitic stress relief structure.

[0048] A ring-shaped axial vibration damping stress groove 25 is excavated on the hollow inner wall of the rotor shaft 21. The ring-shaped axial vibration damping stress groove 25 is located on the hollow inner wall of the rotor shaft 21 near the mounting position of the first drive bearing 231; specifically, the axial projection of the ring-shaped axial vibration damping stress groove 25 partially overlaps with the inner ring mounting position of the first drive bearing 231. This ring-shaped axial vibration damping stress groove 25 forms an integrated flexible hinge structure by locally thinning the metal wall thickness; simultaneously, both sides of the ring-shaped axial vibration damping stress groove 25 adopt a large-radius chamfer design to eliminate stress concentration and improve fatigue life.

[0049] The technical advantages of this structure are as follows: the annular axial damping stress groove 25 maintains a continuous structure in the circumferential direction to preserve the torsional stiffness of the rotor shaft 21; at the same time, the locally thinned area allows the rotor shaft 21 to generate limited elastic clearance in the axial and radial directions. When there are slight misalignments between the three bearing supports, the annular axial damping stress groove 25 can absorb some of the parasitic stress caused by assembly deviations, thereby reducing the risk of bearing jamming and abnormal wear.

[0050] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A frameless motor turntable with load isolation and self-centering conical surface docking, characterized in that, include: The turntable base has a stator housing fixed on its mounting surface; The power input shaft system includes a rotor shaft, a frameless motor, and a first shaft bearing pair. The rotor shaft is coaxially disposed within the stator housing, and the frameless motor and the first shaft bearing pair are disposed between the rotor shaft and the stator housing. The load output shaft system includes a drive shaft and a second shaft bearing. The drive shaft is coaxially disposed within the turntable base, and the second shaft bearing is disposed between the drive shaft and the turntable base. The rotor shaft and the transmission shaft are coaxially connected, and the contact end faces of the rotor shaft and the transmission shaft are mutually fitted convex and concave conical surfaces; the rotor shaft is a hollow structure and the inner wall is provided with an annular axial vibration damping stress groove near the convex conical surface.

2. The frameless motor turntable with load isolation and conical self-centering docking as described in claim 1, characterized in that, The frameless motor includes a rotor and a stator that are arranged in a mutually cooperating manner. The rotor is fixed to the outer wall of the rotor shaft, and the stator is fixed to the inner wall of the stator housing.

3. The frameless motor turntable with load isolation and self-centering conical surface docking as described in claim 1, characterized in that, The first shaft bearing pair includes a first drive bearing and a second drive bearing symmetrically arranged on both sides of the frameless motor, used to constrain the radial runout and axial runout of the rotor shaft in order to maintain the electromagnetic air gap between the rotor and stator of the frameless motor.

4. The frameless motor turntable with load isolation and conical self-centering docking as described in claim 3, characterized in that, The first drive bearing is located close to the convex conical surface, and the axial projection of the annular axial damping stress groove overlaps with the inner ring mounting position of the first drive bearing.

5. The frameless motor turntable with load isolation and conical self-centering docking as described in claim 1, characterized in that, The second shaft bearing is a single rigid high-load bearing, which is either a crossed roller bearing or a double-row angular contact ball bearing.

6. The frameless motor turntable with load isolation and conical self-centering docking as described in claim 1, characterized in that, The output end face of the rotor shaft is a convex conical surface, and the input end face of the transmission shaft is a concave conical surface. The semi-cone angle between the convex and concave conical surfaces is... Satisfy the constraints: ； In the formula, The coefficient of static friction between the materials in contact with the convex and concave conical surfaces. This is the incremental angle of the slight slip.

7. The frameless motor turntable with load isolation and conical self-centering docking as described in claim 6, characterized in that, The rotor shaft and its convex conical surface are integrally machined, and the drive shaft and its concave conical surface are integrally machined.

8. The frameless motor turntable with load isolation and conical self-centering docking as described in claim 1, characterized in that, The annular axial vibration damping stress groove is formed by locally thinning the wall thickness of the rotor shaft, and both sides of the annular axial vibration damping stress groove are arc-shaped transition surfaces.

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