CN102055373B - Multi-rotor cylindrical high-torque ultrasonic motor - Google Patents

Abstract

A multi-rotor cylindrical high-torque ultrasonic motor in the field of ultrasonic application technology, comprising: a piezoelectric ceramic element, a stator, a rotor and a positioning mechanism, one or more rotors are vertically arranged on the positioning mechanism in turn and contact with the stator, and the positioning The mechanism, the rotor and the stator are coaxially arranged, the piezoelectric ceramic element is arranged outside the stator and the rotor is arranged inside the stator or the piezoelectric ceramic element is arranged inside the stator and the rotor is arranged outside the stator. The present invention utilizes the advantage that more piezoelectric ceramics can be attached to the slender cylindrical stator, increases the energy density of the stator vibration, and improves the output torque of the motor; at the same time, it utilizes the characteristic of the uniform angular velocity of the traveling wave propagation on the stator to make the stator drive The multi-rotors rotate synchronously to obtain a uniform output speed, which is conducive to the stable operation of the motor; the slender structure is also conducive to the application in narrow and long spaces.

Description

Multi-rotor Cylindrical High Torque Ultrasonic Motor

technical field

The invention relates to a device in the field of ultrasonic application technology, in particular to a multi-rotor cylindrical high-torque ultrasonic motor vibrating in-plane.

Background technique

Ultrasonic motors use the inverse piezoelectric effect of piezoelectric materials to convert electrical energy into vibration energy of the stator of the ultrasonic motor, and then convert the vibration energy into rotation or linear motion of moving parts through friction. It is generally mainly composed of a stator, a rotor (mover) and a pre-pressure mechanism. Compared with traditional electromagnetic motors, ultrasonic motors have many features and advantages, such as:

1. Compact structure, high energy density (torque/mass), easy to miniaturize.

2. Low speed and high torque, without gear reduction mechanism, can realize direct drive.

3. The motor responds quickly and can realize self-locking when power off.

4. Good position and speed control, high displacement resolution.

5. The ultrasonic motor converts energy through vibration and friction. During the conversion process, it does not generate a magnetic field, nor is it disturbed by an external magnetic field, and has a strong ability to resist electromagnetic interference.

6. Quiet and no noise. The ultrasonic motor works in the ultrasonic frequency band, and since it does not require gears and other reduction mechanisms, it can run quietly and without noise.

7. Flexible design and diverse structural forms.

Traveling wave ultrasonic motor is a common ultrasonic motor, because of its compact sheet-shaped structure, stable operation, and high power, it has been widely used. The working principle of the traveling wave ultrasonic motor is shown in Figure 1, which is mainly composed of an output shaft, a rotor, an end cover, a stator, a base, and a piezoelectric sheet. The piezoelectric sheet excites the traveling wave vibration propagating in the circumferential direction on the stator, and the vibration energy of the stator base is converted into the rotational motion of the rotor through friction between the stator and the rotor.

In order to obtain a larger output torque, people try to improve the structure of the wave-type ultrasonic motor, and propose a single-stator double-rotor structure. The schematic diagram of the structure is shown in Figure 2. composition. The traveling wave is excited on the stator by piezoelectric ceramics, and the rotor is driven by the positive and negative driving surfaces of the stator. Due to the good consistency of the vibration characteristics on both sides of the stator, the traveling-wave ultrasonic motor with a single-stator and double-rotor structure has good stability and a significant increase in torque.

In order to further increase the output torque, there is another attempt with double stators and single rotor, the schematic diagram of which is shown in Figure 3. It is mainly composed of stator, rotor, piezoelectric ceramic elements and friction materials. The upper and lower stators press the rotor at the same time, and the upper and lower stators are simultaneously excited to deform the upper and lower stators at the same time, and the two stators act together on the rotor. However, since the working frequency, rotational speed, and amplitude of the two stators are inconsistent, the loss is serious, the vibration efficiency is low, and the modal interference is serious, which is difficult to realize in engineering. The method of multiple motors in series also has the above-mentioned problems that cannot be overcome. The different stators have to be excited separately, and the excitation of the stators becomes difficult, and it is difficult to ensure synchronization. Therefore, the output torque is not linearly superimposed, but unstable, even more than a single motor. smaller.

Miniaturization is also a development trend of ultrasonic motors. How to obtain a stable larger torque, especially in some places where the space is narrow and not suitable for the installation of a disc traveling wave motor, how to obtain a large torque becomes a difficult problem.

Contents of the invention

The present invention aims at the above-mentioned deficiencies existing in the prior art, and provides a multi-rotor cylindrical high-torque ultrasonic motor, which can increase the energy density of the stator vibration by utilizing the advantage that more piezoelectric ceramics can be attached to the slender cylindrical stator. The output torque of the motor is greatly improved; at the same time, the angular velocity of the traveling wave propagation on the stator is consistent, so that the stator drives the multi-rotor to rotate synchronously, and a uniform output speed is obtained, which is conducive to the stable operation of the motor; application. The novel high-torque motor proposed by the invention will help expand the application field of the ultrasonic motor.

The present invention is achieved through the following technical solutions. The present invention includes: a piezoelectric ceramic element, a stator, a rotor and a positioning mechanism, wherein: one or more rotors are arranged vertically on the positioning mechanism in turn and are in contact with the stator; the positioning mechanism, the rotor Both are arranged coaxially with the stator, the piezoelectric ceramic element is arranged outside the stator and the rotor is arranged inside the stator or the piezoelectric ceramic element is arranged inside the stator and the rotor is arranged outside the stator.

All rotors rotate synchronously at the same angular velocity;

The inner wall or outer wall of the stator is a center-symmetrical structure, and its cross-section is circular or polygonal. The stator is provided with several driving surfaces corresponding to the rotors to drive multiple coaxial rotors to rotate synchronously.

The rotor is a disc-shaped structure or a ring-shaped structure, wherein:

An elastic mechanism is provided between the disc-shaped rotors, the rotor matches the shape of the driving surface, and the elastic mechanism and the driving surface are respectively located on both sides of any rotor.

The elastic mechanism is a compression spring;

The rotor of the ring structure is an open ring, and the two ends of the open ring are provided with tension springs to realize the clamping of the rotor on the stator.

The positioning mechanism is a positioning shaft or a positioning cover. When the rotor is arranged inside the stator, the positioning mechanism is located inside the stator and the rotor is fixedly arranged on the positioning mechanism; when the rotor is arranged outside the stator, the positioning mechanism is located on the inside of the stator. both ends and in contact with the rotor.

When the section of the inner wall of the stator is circular, the piezoelectric ceramic element is arranged on the outer wall of the stator in the axial direction of the stator; when the section of the outer wall of the stator is circular, the piezoelectric ceramic element is arranged on the outer wall of the stator in the axial direction of the stator inner wall of the stator.

The piezoelectric ceramics are arranged on the stator in the axial direction of the stator, and can excite the vibration mode shown in Figure 5 on the stator, that is, the vibration of the particle on the stator is a two-dimensional vibration, and there is no vibration along the axial direction, that is, the stator The vibration trajectory of the upper particle is always in the plane perpendicular to the axis where it is located.

Features and effects of the present invention: the present invention increases the energy density of the stator vibration and improves the output torque of the motor; the stator drives the multi-rotors to rotate synchronously, and the motor works stably; the slender structure is also conducive to the application in narrow and long spaces. The novel high-torque motor proposed by the invention will help expand the application field of the ultrasonic motor, and has broad application prospects in biology, medical treatment, micro-machinery, national defense technology and the like.

Description of drawings

Figure 1 Structural schematic diagram of ordinary traveling wave ultrasonic motor

Wherein: 11 is an output shaft, 12 is a rotor, 13 is an end cover, 14 is a stator, 15 is a base, and 16 is a piezoelectric sheet.

Figure 2 Structural schematic diagram of single stator and double rotor traveling wave ultrasonic motor

Wherein: 21 is a rotor, 22 is a piezoelectric ceramic element, 23 is a friction material, and 24 is a stator.

Figure 3 Structural schematic diagram of double stator single rotor traveling wave ultrasonic motor

Wherein: 31 is a stator, 32 is a rotor, 33 is a ceramic element, and 34 is a friction material.

Fig. 4 is a schematic diagram of the structure of the present invention.

Where: 41 is a piezoelectric ceramic element, 42 is a stator, 43 is a rotor, 44 is a positioning mechanism, 45 is an elastic mechanism, 46 is an output shaft and 47 is a driving surface of a stator.

Fig. 5 is the schematic diagram of embodiment 1 in-plane vibration mode shape;

Where: n=2 represents the second-order in-plane vibration mode, n=3 represents the third-order in-plane vibration mode, and n=4 represents the fourth-order in-plane vibration mode.

Figure 6 is a schematic diagram of the bonding method of piezoelectric ceramics in Embodiments 1 and 2 of multi-rotor high-torque cylindrical ultrasonic motors.

Among them: 61, 62, 63, 64, 65, 66, 67, and 68 are piezoelectric ceramic elements, 69 is a stator elastic body, and 610 is a trapezoidal boss inside the stator.

FIG. 7 is a schematic structural diagram of Embodiment 2.

Among them: 71 is a piezoelectric ceramic element, 72 is a groove stator, 73 is a rotor, 74 is a leaf spring, 75 is a compression spring, and 76 is a rotating shaft.

Fig. 8 is a schematic structural diagram of Embodiment 3 of a multi-rotor high-torque cylindrical ultrasonic motor.

Among them: 81 is the fixed end, 82 is the rotor, 83 is the upper boss of the stator, 84 is the stator, and 85 is the piezoelectric ceramic component.

Fig. 9 is a schematic diagram of the bonding method of piezoelectric ceramics in Embodiment 3 of the multi-rotor high-torque cylindrical ultrasonic motor.

Among them: 91, 92, 93, 94, 95, 96, 97, 98 piezoelectric ceramics, 99 is the rotor, 910 is the stator base.

Fig. 10 is a schematic diagram of the rotor structure of Example 3 of the multi-rotor high-torque cylindrical ultrasonic motor.

Detailed ways

The following is a detailed description of the embodiments of the present invention. This embodiment is implemented on the premise of the technical solution of the present invention, and detailed implementation methods and specific operating procedures are provided, but the protection scope of the present invention is not limited to the following implementation example.

As shown in FIG. 4 , this embodiment includes: a piezoelectric ceramic element 41 , a stator 42 , a rotor 43 and a positioning mechanism 44 . Wherein: one or more rotors 43 are vertically arranged on the positioning mechanism 44 in turn and contact with the stator 42, the positioning mechanism 44, the rotor 43 and the stator 42 are all coaxially arranged, the piezoelectric ceramic element 41 is arranged on the outside of the stator 42 and The rotor 43 is provided inside the stator 42 .

The inner wall of the stator 42 is circular, and the outer wall of the stator 42 is polygonal. The stator 42 is provided with several driving surfaces 47 corresponding to the rotors 43 to drive multiple coaxial rotors 43 to rotate synchronously.

The piezoelectric ceramic element 41 is a strip-shaped plate structure, polarized along the thickness direction, and the piezoelectric ceramic element 41 is arranged on the outer wall of the stator 42 in an axial manner of the stator 42;

The positioning mechanism 44 is a positioning shaft, the positioning mechanism 44 is located inside the stator 42 and the rotor 43 is fixedly arranged on the positioning shaft through a key and an elastic mechanism.

The rotor 43 is a disc-shaped structure, wherein:

An elastic mechanism 45 is provided between the disc-shaped rotors 43 , the rotor 43 matches the shape of the driving surface 47 and the elastic mechanism 45 and the driving surface 47 are respectively located on both sides of any rotor 43 .

Described elastic mechanism 45 is stage clip;

As shown in Figure 5, it is a schematic diagram of the second, third and fourth order in-plane vibration mode shapes of the stator. n=2 represents the mode shape of the second-order in-plane vibration mode. When two driving signals with the same frequency but with a phase difference of 90 degrees are applied to the piezoelectric ceramic element of the stator, two standing waves with a difference of 90 degrees in time and space will be excited on the stator at the same time, and the two standing waves are synthesized A traveling wave that rotates in the circumferential direction, so that the motion trajectories of the particles on the driving surface on the stator are all ellipses. It is the elliptical motion of the mass that causes the stator to rotate the rotor in contact with it. Since the rotational angular velocity of the traveling wave rotating along the circumferential direction on the stator is the same, even if the radii of multiple rotors are different, the angular velocity of the stator driving these rotors is still the same, which makes the output torque of multiple rotors superimposed effectively.

In order to obtain a certain order of traveling wave vibration on the stator, it is necessary to design ceramic bonding and excitation methods. As shown in Figure 6, it is the excitation method of the second-order in-plane vibration traveling wave. Eight piezoelectric ceramic sheets are pasted on the outer prism surface of the stator. When pasting, if the polarization directions of the piezoelectric ceramic sheets 61, 63, 65, and 67 are the same as the normal direction of the pasting plane, and the polarization directions of the piezoelectric ceramic sheets 62, 64, 66, 68 are opposite to the normal direction of the pasting plane , then 61, 63, 65, 67 add the sinωt excitation signal, and 62, 64, 66, 68 add the Acosωt excitation signal. If all the piezoelectric sheets are pasted in the same direction, the piezoelectric ceramic sheets 61, 62, 63, 64, 65, 66, 67, 68 sequentially add excitation signals Asinωt, Acosωt, -Asinωt, -Acosωt, Asinωt, Acosωt, -Asinωt, -Acosωt.

When the second-order in-plane vibration traveling wave is used, the pasted sides of the piezoelectric ceramic component on the stator can be 6 sides or other values, which only correspond to different excitation methods. When 6 sides are used, if the polarization direction of the piezoelectric ceramic is the same as the normal direction of the pasting surface, the excitation signals Asinωt, Asin(ωt+2π/3), Asin(ωt+ 4π/3), Asinωt, Asin(ωt+2π/3), Asin(ωt+4π/3), at this time, a second-order in-plane traveling wave will be excited on the stator. If there is a piezoelectric ceramic among them according to the relationship between the polarization direction and the normal direction of the pasted surface, when it is pasted in the opposite way to the original, the corresponding excitation signal will also become the opposite signal.

When the third-order in-plane vibration traveling wave is used, the above-mentioned piezoelectric ceramic components on the stator can have 9 sides or 12 sides or other values, corresponding to different excitation methods. When 9 sides are used, if the piezoelectric ceramics are pasted in the same way that the polarization direction is the same as the normal direction of the pasting surface, the 9 piezoelectric ceramics are sequentially added with signals Asinωt, Asin(ωt+2π/3), Asin(ωt+4π /3), Asinωt, Asin(ωt+2π/3), Asin(ωt+4π/3), Asinωt, Asin(ωt+2π/3), Asin(ωt+4π/3), at this time, the The third-order in-plane traveling wave is excited above. When 12 sides are used, if the piezoelectric ceramics are pasted in the same way as the polarization direction and the normal direction of the pasting surface, the 12 piezoelectric ceramics are sequentially given signals Asinωt, Acosωt, -Asinωt, -Acosωt, Asinωt, Acosωt, -Asinωt, -Acosωt, Asinωt, Acosωt, -Asinωt, -Acosωt. At this time, a third-order in-plane traveling wave will be excited on the stator. Similarly, if the piezoelectric ceramics are pasted in the opposite way according to the relationship between the polarization direction and the normal direction of the paste surface, the corresponding excitation signal will also become the opposite signal. The excitation method of higher order modes is the same.

Example 2

As shown in Figure 7, in this embodiment: the multi-rotor ultrasonic motor with stepped stator inner surface contact includes 71 piezoelectric ceramic elements, 72 grooved stators, 73 rotors, 74 leaf springs, 75 compression springs, 76 shaft. There are grooves on the outer surface of the polygonal column of the cylindrical stator, and the piezoelectric ceramic elements are pasted in segments. The plane in the groove may or may not be bonded with piezoelectric ceramic elements. Although there are grooves on the outer surface of the polygonal column of the cylindrical stator, the piezoelectric ceramic elements are pasted in sections, but the ceramics pasted in sections are still considered as a group. Eight groups of piezoelectric ceramic sheets are pasted on the outer prism surface of the stator.

The stator adopts the in-plane vibration mode shown in Fig. 5 as the working mode. The bonding and modal excitation method of the piezoelectric ceramics are the same as in the first embodiment.

Example 3:

As shown in FIG. 8 , in this embodiment: the outer wall of the stator 84 is circular, the inner wall of the stator 84 is polygonal, and the rotor 82 is arranged outside the stator 84 .

The positioning mechanism 4 is a positioning cover, and the positioning mechanism 4 is located at both ends of the stator 2 for supporting and fixing the stator.

The rotor 82 is an annular structure, and its structure description is shown in Figure 10, wherein: the rotor 101 of the annular structure is an open ring, and the two ends 102 of the open ring are provided with tension springs 103 In order to realize that the rotor 101 is fastened to the stator 84 .

The piezoelectric ceramic element 85 is a strip-shaped plate structure, and the piezoelectric ceramic element 85 is arranged on the inner wall of the stator 2 in the axial direction of the stator 84 .

The pasting of the piezoelectric ceramics and the excitation mode of the mode are the same as in the first embodiment.

Claims (7)

1. A multi-rotor cylindrical high-torque ultrasonic motor, comprising: piezoelectric ceramic element, stator, rotor and positioning mechanism, is characterized in that: one or more rotors are vertically arranged on the positioning mechanism successively and contact with the stator, The positioning mechanism, the rotor and the stator are coaxially arranged, the piezoelectric ceramic element is arranged outside the stator and the rotor is arranged inside the stator, or the piezoelectric ceramic element is arranged inside the stator and the rotor is arranged outside the stator; The rotor is a disc-shaped structure or a ring-shaped structure, wherein: an elastic mechanism is arranged between the rotors of the disc-shaped structure, the rotor matches the shape of the driving surface and the elastic mechanism and the driving surface are respectively located at any both sides of the rotor; When two driving signals with the same frequency but with a phase difference are applied to the piezoelectric ceramic element of the stator, two standing waves with the same phase difference in time and space will be simultaneously excited on the stator, and the two standing waves will be combined into one Traveling waves rotating along the circumferential direction, so that the motion trajectories of the particles on the driving surface on the stator are all ellipses, so that the stator drives the rotor in contact with it to rotate; since the traveling waves rotating along the circumferential direction on the stator have the same rotational angular velocity , so even if the radii of multiple rotors are different, the angular velocity driven by the stator to these rotors is still the same, so that the output torques of multiple rotors can be effectively superimposed. 2. The multi-rotor cylindrical high-torque ultrasonic motor according to claim 1, wherein all the rotors rotate synchronously at the same angular velocity. 3. The multi-rotor cylindrical high-torque ultrasonic motor according to claim 1 or 2, characterized in that, the inner wall or outer wall of the stator is a center-symmetrical structure, and its cross section is circular or polygonal, and the stator is provided with A plurality of driving surfaces corresponding to the rotors drives a plurality of coaxial rotors to rotate synchronously. 4. The multi-rotor cylindrical high-torque ultrasonic motor according to claim 1, wherein the elastic mechanism is a compression spring. 5. The multi-rotor cylindrical high-torque ultrasonic motor according to claim 1, characterized in that, the rotor of the annular structure is an open ring, and the two ends of the open ring are provided with extension springs In order to realize the clamping of the rotor on the stator. 6. The multi-rotor cylindrical high-torque ultrasonic motor according to claim 1, wherein the positioning mechanism is a positioning shaft or a positioning cover, and when the rotor is arranged inside the stator, the positioning mechanism is located inside the stator And the rotor is fixedly arranged on the positioning mechanism; when the rotor is arranged outside the stator, the positioning mechanism is located at both ends of the stator. 7. The multi-rotor cylindrical high-torque ultrasonic motor according to claim 1, wherein the specific position of the piezoelectric ceramic element is any one of the following two ways: 1) When the section of the inner wall of the stator is circular, the piezoelectric ceramic element is arranged on the outer wall of the stator in the axial direction of the stator; 2) When the section of the outer wall of the stator is circular, the piezoelectric ceramic element is arranged on the inner wall of the stator in the axial direction of the stator.

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