Adjustable pre-tightening force traveling wave ultrasonic motor

Abstract

The application provides a kind of adjustable pre-tightening force traveling wave ultrasonic motor, which comprises a shell, a rotating shaft is connected in the center of the shell, the waist of the rotating shaft is connected with a rotor, the end face of the rotor is in contact with a stator tooth on the end face of a stator, piezoelectric ceramics are distributed along the circumference on the other end face of the stator, the stator is fixedly connected with the shell; the shell is connected with an end cover; a pre-tightening force screw is threadedly connected in the center of the end cover, the center of the pre-tightening force screw is rotatably connected with one end of the rotor, the other end of the rotor is rotatably connected with the center of the shell; an elastic member is further sleeved on the rotating shaft, one end of the elastic member is pressed on the pre-tightening force screw through a thrust bearing, and the other end of the elastic member presses the rotor tightly on the stator tooth on the end face of the stator. The pre-tightening force between the rotor and the stator of the ultrasonic motor can be adjusted by adjusting the tightening depth of the pre-tightening force screw.

Description

Technical Field

[0001] This invention belongs to the field of ultrasonic motor technology, and specifically relates to a traveling wave ultrasonic motor with adjustable preload. Background Technology

[0002] Ultrasonic motors are special motors used in actuation. Their stator and rotor structures generate rotational motion under the drive of friction. In order for the actuator to operate normally, a certain preload needs to be applied between the stator and rotor. Currently, the preload is basically applied by the deformation generated by the stator or rotor.

[0003] In practical engineering applications, the deformation preload displacement generated by the traveling wave ultrasonic motor structure itself is extremely limited. Generally, after long-term operation, the friction material of an ultrasonic motor will wear and thin, which will greatly reduce the preload effect between the stator and rotor, leading to a significant decrease in the motor's mechanical performance and a substantial reduction in its lifespan. In particular, the wear rate will surge in complex environments. This defect limits the widespread application of ultrasonic motors in other fields.

[0004] In common ultrasonic motors, the preload is applied during assembly using fixed shims or elastic elements in fixed positions. Existing patented solutions, such as the CN1299181A standing wave self-correcting ultrasonic motor, typically employ fixed-position elastic elements or other disc springs with radial grooves to apply the preload. However, disc springs are difficult to manufacture, have high process complexity, and their effectiveness is unsatisfactory, hindering their application due to various constraints. Therefore, when testing for poor piezoelectric ceramic excitation, it is necessary to disassemble and adjust the preload, significantly wasting product production time and making it difficult to establish effective assembly standards. Summary of the Invention

[0005] This invention provides a traveling wave ultrasonic motor with adjustable preload. The preload between the rotor and stator of the ultrasonic motor can be adjusted by regulating the tightening depth of the preload screw.

[0006] Technical Solution. A traveling wave ultrasonic motor with adjustable preload includes a housing, a rotating shaft rotatably connected to the center of the housing, a rotor connected to the waist of the rotating shaft, a rotor end face contacting stator teeth on the stator end face, piezoelectric ceramics distributed circumferentially on the other end face of the stator, and the stator fixedly connected to the housing; the housing is connected to an end cover; a preload screw is threadedly connected to the center of the end cover, the center of the preload screw is rotatably connected to one end of the rotor, and the other end of the rotor is rotatably connected to the center of the housing; an elastic element is also sleeved on the rotating shaft, one end of the elastic element abuts against the preload screw, and the other end presses the rotor against the stator teeth on the stator end face via a thrust bearing.

[0007] In the aforementioned adjustable preload traveling wave ultrasonic motor, a flange is provided on the waist of the shaft, and the waist flange is fixedly connected to the rotor disc surface by screws.

[0008] In the aforementioned adjustable preload traveling wave ultrasonic motor, the two ends of the rotating shaft are rotatably connected to the center of the outer shell and the center of the preload screw via bushing bearing A and bushing bearing B, respectively.

[0009] In the aforementioned adjustable preload traveling wave ultrasonic motor, limit flanges are provided at both ends of the rotating shaft near the bearings A and B of the bushing.

[0010] In the aforementioned adjustable preload traveling wave ultrasonic motor, flanges are provided at the opposite ends of the bushing bearings A and B.

[0011] In the aforementioned adjustable preload traveling wave ultrasonic motor, the piezoelectric ceramic is bonded to the stator.

[0012] In the aforementioned adjustable preload traveling wave ultrasonic motor, a slot is provided on the end face of the shaft.

[0013] In the aforementioned adjustable preload traveling wave ultrasonic motor, after the piezoelectric ceramic is subjected to sine and cosine excitation signals, the stator generates a bending vibration mode, which drives the rotor and shaft to move through friction.

[0014] Beneficial effects: 1. This invention allows for easier adjustment of the preload of the ultrasonic motor via the preload screw after product assembly, thereby achieving a better effect of stimulating rotor rotation.

[0015] 2. The present invention can increase the rotational life by setting a graphite bushing bearing as the rotating shaft structure.

[0016] 3. The present invention, by setting a multi-level flange structure on the rotating shaft, can prevent the rotating shaft from falling off when the internal connection of the product fails, thereby increasing reliability. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. The drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of a traveling wave ultrasonic motor with adjustable preload according to the present invention.

[0019] Figure 2 This is a schematic diagram of a cross-sectional view of a traveling wave ultrasonic motor with adjustable preload according to the present invention.

[0020] Figure 3This is a schematic diagram of a traveling wave ultrasonic motor stator and rotor assembly with adjustable preload according to the present invention.

[0021] Figure 4 This is a schematic diagram of a traveling wave ultrasonic motor preload assembly with adjustable preload according to the present invention.

[0022] Figure 5 This is a schematic diagram of a traveling wave ultrasonic motor shaft with adjustable preload according to the present invention.

[0023] Figure 6 This is a schematic diagram of an adjustable preload traveling wave ultrasonic motor preload screw according to the present invention. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] The features and illustrative embodiments of various aspects of the present invention will now be described in detail. Numerous specific details are set forth in the following detailed description to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention may be practiced without requiring some of these specific details. The following description of embodiments is merely intended to provide a better understanding of the invention by illustrating examples of the invention. The invention is by no means limited to any specific setups and methods set forth below, but covers any improvements, substitutions, and modifications to structures, methods, and devices without departing from the spirit of the invention. Well-known structures and techniques are not shown in the drawings and the following description to avoid unnecessarily obscuring the invention.

[0026] In the description of this invention, it should be noted that the directions or positional relationships indicated by terms such as "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer" are based on the directions or positional relationships shown in the accompanying drawings and are only for the convenience of describing and simplifying the invention, and should not be construed as limiting the invention. Furthermore, the use of ordinal numbers (e.g., "first and second," etc.) is for distinguishing objects and is not limited to this order, and should not be construed as indicating or implying relative importance.

[0027] 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, encompassing both direct connection and indirect connection via an intermediate medium. Those skilled in the art can understand the specific meaning of these terms in this invention based on the specific circumstances.

[0028] It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other, and the various embodiments can be referenced and cited in each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0029] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0030] Example 1. A traveling wave ultrasonic motor with adjustable preload, see [link to example]. Figures 1-6 It includes: housing 1, bushing bearing 12, piezoelectric ceramic 3, stator 4, rotor 5, rotating shaft 6, thrust bearing 7, preload assembly, end cover 9, and screws 12, wherein: The piezoelectric ceramic 3 is bonded to the stator 4; the rotor 5 is connected to the shaft 6 by screws; the shaft 6 is rotatably connected to the bearing bushings 2 and 8 through their shaft holes; the bearing bushing 2 is connected to the outer shell 1 through its shaft hole; the outer shell 1 is connected to the stator 4 by screws; the outer shell 1 is connected to the end cover 9 by screws; the end cover 9 is connected to the preload assembly by threads; the preload assembly includes a preload screw 10, a thrust bearing 7, and an elastic element 11; the preload screw 10 and the elastic element 11 are engaged by a U-shaped groove. Preferably, the traveling wave stator-rotor assembly is an ultrasonic motor that drives the rotor 5 and the shaft 6 to move by friction after the stator 4 generates a high-frequency elliptical motion in a bending vibration mode following the application of sine and cosine excitation signals to the specially arranged piezoelectric ceramics 3.

[0031] In the friction-transmitted rotation structure, sufficient contact between stator 4 and rotor 5 is required. At the same time, in order to output a larger torque, sufficient contact between stator 4 and rotor 5 is also required. When the friction factor is constant, the magnitude of the axial force needs to be changed to increase the rotational friction torque. The axial force needs to be adjusted to a suitable magnitude to stimulate a better rotational effect.

[0032] Preferably, the stator 4 is fixed to the housing 1 by screws 12, the rotor 5 is fixed to the shaft 6 by screws 12, the two ends of the shaft 6 are supported by bearing bushings 2 and 8, and the flanges at both ends of the shaft 6 prevent the shaft from coming off when the screws 12 fail. In addition, when the preload provided by the elastic element 11 is insufficient, appropriate preload can be provided by cooperating with the preload screw 10.

[0033] Preferably, the contact force between the stator 4 and the rotor 5 is pre-tightened by the elastic element 11, and the compression of the elastic element 11 is adjusted by the pre-tightening screw 10. Thrust bearings 7 are provided at both ends of the elastic element 11 to prevent the elastic element from affecting the pre-tightening effect as it rotates with the shaft.

[0034] Example 2. A traveling wave ultrasonic motor with adjustable preload, see [link to example]. Figures 1-6 ,in: The stator and rotor assembly includes a piezoelectric ceramic 3, a stator 4, a rotor 5, a shaft 6, and ordinary screws 12; The piezoelectric ceramic 3 is connected to the stator 4 by adhesive bonding; The rotor 5 is connected to the shaft 6 by screws; The rotating shaft 6 is rotatably connected to the bearing bushings 2 and 8 through the shaft holes. The bearing bushing 2 is connected to the outer shell 1 through a shaft hole; The outer casing 1 and the stator 4 are connected by screws; The outer casing 1 and the end cap 9 are connected by screws; The end cap 9 is connected to the pre-tightening force assembly by a thread; The preload assembly includes a preload screw 10, a thrust bearing 7, and an elastic element 11; The preload screw 10 and the elastic element 11 are engaged by a U-shaped groove; The aforementioned stator and rotor assembly is a structure in which the stator 4 generates bending vibration modes after the piezoelectric ceramic 3 is subjected to sine and cosine excitation signals, and drives the rotor 5 and the shaft 6 to move through friction.

[0035] The aforementioned rotating shaft 6 adopts a three-stage flange structure. The middle flange has a threaded hole and is connected to the rotor 5 by screws. At the same time, the middle flange has a groove to accommodate the thrust bearing 7. The flanges of the lower flange of the rotating shaft 6 and the bearing sleeves 2 and 8 can prevent excessive slippage of the rotating shaft when the screws fall off. The upper flange of the rotating shaft 6 provides a constant mechanical preload generated by compression when the preload provided by the elastic element 11 is insufficient. The upper end of the rotating shaft 6 has a slot to indicate the position when the rotating shaft rotates. The lower end of the rotating shaft 6 has a boss to connect with other rotating shafts for output and transmission of rotation. The aforementioned rotating shaft 6 is connected to the bearing bushings 2 and 8 by a rotating fit through the shaft hole; the bearing bushings 2 and 8 are made of graphite composite material flanged bushings or alloy bushings with good lubrication, and the flange can reduce rotational friction.

[0036] A sealing gasket is provided at the connection between the aforementioned outer casing 1 and the end cap 9.

[0037] In the aforementioned preload assembly, the preload is provided by the elastic element 11. The elastic element 11 is a cylindrical helical compression spring or disc spring with its ends tightly ground flat. Thrust bearings 7 are provided at both ends of the elastic element 11, which then cooperate with the rotating shaft 6 and the preload screw 10.

[0038] In the aforementioned preload assembly, the preload screw 10 is connected to the end cap 9 via threads; the preload screw 10 engages with the elastic element 11 via a U-shaped groove to prevent the elastic element 11 from moving, and provides compression to the elastic element 11 by tightening. The aforementioned preload screw 10 has an external hexagonal shape or other polygonal shape on its end face for easy tightening.

[0039] The above detailed embodiments are a description of the present invention. It should not be considered that the specific embodiments of the present invention are limited to these descriptions. For those skilled in the art, several simple deductions and substitutions can be made without departing from the concept of the present invention, and all of these should be considered to fall within the protection scope of the present invention.

Claims

1. A traveling wave ultrasonic motor with adjustable preload, characterized in that, The device includes a housing (1), a rotating shaft (6) rotatably connected to the center of the housing (1), a rotor (5) connected to the waist of the rotating shaft (6), a stator tooth on the end face of the rotor (5) contacting the end face of the stator (4), piezoelectric ceramics (3) distributed circumferentially on the other end face of the stator (4), and the stator (4) fixedly connected to the housing (1); the housing (1) is connected to the end cover (9); a preload screw (10) is threadedly connected to the center of the end cover (9), the center of the preload screw (10) is rotatably connected to one end of the rotor (5), and the other end of the rotor (5) is rotatably connected to the center of the housing (1); an elastic element (11) is also fitted on the rotating shaft (6), one end of the elastic element (11) rests on the preload screw (10), and the other end presses the rotor (5) against the stator tooth on the end face of the stator (4) via a thrust bearing (7).

2. The adjustable preload traveling wave ultrasonic motor according to claim 1, characterized in that, A flange is provided at the waist of the shaft (6), and the waist flange is fixedly connected to the disc of the rotor (5) by screws (12).

3. The adjustable preload traveling wave ultrasonic motor according to claim 1, characterized in that, The two ends of the rotating shaft (6) are rotatably connected to the center of the outer shell (1) and the center of the preload screw (10) via the bushing bearing A (2) and bushing bearing B (8).

4. The adjustable preload traveling wave ultrasonic motor according to claim 3, characterized in that, Limiting flanges are provided at both ends of the rotating shaft (6) near the bearings A and B of the bushing.

5. The adjustable preload traveling wave ultrasonic motor according to claim 3, characterized in that, Both bearing sleeves A and B have flanges on their opposite ends.

6. The adjustable preload traveling wave ultrasonic motor according to claim 1, characterized in that, The piezoelectric ceramic (3) and the stator (4) are connected by adhesive bonding.

7. The adjustable preload traveling wave ultrasonic motor according to claim 1, characterized in that, A slot is provided on the end face of the rotating shaft (6).

8. The adjustable preload traveling wave ultrasonic motor according to claim 1, characterized in that, When the piezoelectric ceramic (3) is subjected to sine and cosine excitation signals, the stator (4) generates a bending vibration mode, which drives the rotor (5) and the shaft (6) to move through friction.

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