A cage-type integrated piezoelectric actuator with moving rotor and its control method

Abstract

The application discloses a cage type dynamic-rotor integrated piezoelectric actuator and a control method thereof. The actuator comprises three parts of a ring-shaped piezoelectric vibrator, a fixed holder and a circular arc slide rail. Two driving feet are symmetrically arranged on the outer side of the ring-shaped piezoelectric vibrator in the diametric direction, and two rotating shafts are arranged in the vertical direction. A plurality of piezoelectric ceramics are symmetrically attached to the grooves on the two sides of the circular ring. The working principle of the application is that two different vibrations are generated by the piezoelectric vibrator, and after coupling, an elliptical motion is output at the driving feet, and the rotation is driven through the reaction force of the friction. The application innovatively designs a stator-rotor integrated piezoelectric rotary actuator. The piezoelectric vibrator is not only a driving power source, but also a motion mechanism, so that the structure and function are integrated, an additional rotor and a fixing device are not needed, the overall structure of the actuator is simplified, and the weight of the actuator is reduced.

Description

Technical Field

[0001] This invention belongs to the field of piezoelectric drive, specifically relating to a cage-type integrated piezoelectric actuator and its control method. Background Technology

[0002] Piezoelectric rotary motors have been widely used in optical engineering and aerospace due to their high precision and large torque. However, existing piezoelectric rotary motors drive the rotor by bonding piezoelectric ceramics to the stator as a piezoelectric vibrator. The stator and rotor also require their own fixing devices, which makes the device structure complex. The contact area between the stator and rotor is small, resulting in low energy transfer efficiency. In addition, the rotor device occupies a certain volume, so the space utilization is low and the structure is not compact. Summary of the Invention

[0003] Purpose of the invention: To address the above-mentioned shortcomings, this invention provides a cage-type integrated piezoelectric actuator and its control method. The piezoelectric actuator features small size, light weight, large torque, high precision, and integrated stator and rotor.

[0004] Technical Solution: To solve the above problems, this invention employs a cage-type integrated piezoelectric actuator, comprising an annular piezoelectric vibrator, a fixed retainer, and an arc-shaped slide rail; the annular piezoelectric vibrator comprises an annular metal substrate and piezoelectric ceramics; the outer ring surface of the annular metal substrate is provided with a set of driving feet located at both ends of the diameter direction of the annular metal substrate and a set of rotating shafts whose axes of symmetry are perpendicular to the axes of symmetry of the driving feet, and the rotating shafts are symmetrical about the lines containing the two driving feet; and the piezoelectric ceramics include four first piezoelectric ceramics and four second piezoelectric ceramics, wherein two first piezoelectric ceramics are located on the upper surface of the annular metal substrate. Two first piezoelectric ceramics are located on one side of the axis of rotation, and two second piezoelectric ceramics are located on the lower surface of the annular metal substrate and on the other side of the axis of rotation. Two second piezoelectric ceramics are located on the lower surface of the annular metal substrate and on one side of the axis of rotation, and two second piezoelectric ceramics are located on the upper surface of the annular metal substrate and on the other side of the axis of rotation. The projections of one first piezoelectric ceramic and one second piezoelectric ceramic on the upper and lower surfaces of the annular metal substrate coincide. The piezoelectric ceramics located on the upper surface of the annular metal substrate have the same polarization direction, and the piezoelectric ceramics located on the lower surface of the annular metal substrate have the opposite polarization direction to the piezoelectric ceramics on the upper surface.

[0005] Furthermore, the main body of the retainer is shaped like a semi-circular arc, with through holes at both ends of the semi-circular arc whose centers are in the same diameter direction; ball bearings are installed in the through holes; and the ball bearings are connected to the rotating shaft.

[0006] Furthermore, the annular metal substrate has four fan-shaped slots on both its upper and lower surfaces, with each fan-shaped slot spaced 90° apart at its central angle. Piezoelectric ceramics are placed in the fan-shaped slots one by one. The four piezoelectric ceramics on the upper surface of the annular metal substrate are evenly distributed at equal intervals within the circumference, and the four piezoelectric ceramics on the lower surface of the annular metal substrate are also evenly distributed at equal intervals within the circumference.

[0007] Furthermore, the main body of the arc slide rail is an arc with an opening, and a rectangular protrusion is provided at the opening, which is connected to a tension spring.

[0008] Furthermore, the inner side of the arc section of the fixed retainer has a rectangular groove, and the outer side of the arc section of the arc slide rail also has a rectangular groove. The rectangular groove on the inner side of the fixed retainer and the rectangular groove on the outer side of the arc slide rail fit together.

[0009] Furthermore, the center of the arc of the circular slide rail is located on the straight line connecting the centers of the two ball bearings.

[0010] The control method for the piezoelectric actuator is as follows:

[0011] When the two sets of piezoelectric ceramics are excited by two sets of AC signals, the ring piezoelectric oscillator is simultaneously excited to produce two different vibration modes: an in-plane vibration mode with an even number of peaks and troughs, where both driving feet are simultaneously at a peak or trough; and an out-of-plane vibration mode with an odd number of peaks and troughs, where the two driving feet are respectively at a peak and a trough. When the two sets of piezoelectric ceramics are excited by AC signals with a 90-degree time phase difference, the out-of-plane and in-plane vibration modes of the ring piezoelectric oscillator are coupled. The two driving feet generate elliptical motion with the same rotation direction but a 180-degree phase difference. The frictional reaction force generated by the driving feet and the circular arc slide rail drives the ring piezoelectric oscillator to spin around its own axis. When the phase difference of the two applied AC signals is changed to -90 degrees, the ring piezoelectric oscillator moves in the opposite direction.

[0012] Beneficial effects: Compared with the prior art, the significant advantages of this invention are that it integrates the mover and rotor, reducing the structural complexity and overall size of the actuator; the integrated structural and functional design enables the piezoelectric vibrator to rotate around the axis, serving as both a drive source and a motion mechanism, thus improving the energy utilization rate of the actuator; the driven object can be installed in the cage for rotation, or it can be connected to the piezoelectric actuator shaft via a coupling to output work externally, thus broadening its application range. Attached Figure Description

[0013] Figure 1 A three-dimensional structural diagram of a cage-type integrated piezoelectric actuator;

[0014] Figure 2 Schematic diagram of a ring piezoelectric oscillator;

[0015] Figure 3 This is a schematic diagram of a ring-shaped metal substrate;

[0016] Figure 4 This is a schematic diagram showing the distribution location and polarization direction of piezoelectric ceramics;

[0017] Figure 5 This is a schematic diagram of the cage frame assembly;

[0018] Figure 6 Schematic diagram of a fixed retainer;

[0019] Figure 7 This is a schematic diagram of a circular arc slide rail;

[0020] Figure 8 A three-dimensional diagram of the fourth-order longitudinal vibration modes in the plane of a piezoelectric oscillator;

[0021] Figure 9 This is a planar diagram of the fourth-order longitudinal vibration modes in the plane of a piezoelectric oscillator.

[0022] Figure 10 Three-dimensional diagram of the out-of-plane fifth-order bending vibration modes of the piezoelectric oscillator;

[0023] Figure 11 This is a planar diagram of the out-of-plane fifth-order bending vibration modes of a piezoelectric oscillator.

[0024] Figure 12 This is a schematic diagram illustrating the working principle of a piezoelectric vibrator when it generates motion. Detailed Implementation

[0025] like Figure 1 As shown, a cage-type integrated piezoelectric actuator of this embodiment includes an annular piezoelectric vibrator 1, a fixed cage 2, and an arc-shaped slide rail 3. Figure 2 As shown, the annular piezoelectric vibrator 1 includes an annular metal substrate 4 and a piezoelectric ceramic 5. A set of driving feet 6 located at both ends of the diameter of the annular metal substrate 4 and a set of rotating shafts 7 with axes of symmetry perpendicular to the axes of symmetry of the driving feet 6 are provided on the outer annular surface of the annular metal substrate 4. The rotating shafts 7 are symmetrical about the lines containing the two driving feet 6. Figure 3 As shown, the annular metal substrate 4 has four fan-shaped slots 10 on both its upper and lower surfaces. Each fan-shaped slot 10 is spaced 90° apart by a central angle. The four piezoelectric ceramics 5 on the upper surface of the annular metal substrate 4 are evenly distributed at equal intervals within the circumference. The four piezoelectric ceramics 5 on the lower surface of the annular metal substrate 4 are also evenly distributed at equal intervals within the circumference.

[0026] like Figure 4As shown, piezoelectric ceramics 5 are placed one-to-one in the fan-ring slots 10, and the piezoelectric ceramics 5 include four first piezoelectric ceramics 11 and four second piezoelectric ceramics 12. Two first piezoelectric ceramics 11 are located on the upper surface of the annular metal substrate 4 and on one side of the axis of the rotating shaft 7, and the other two first piezoelectric ceramics 11 are located on the lower surface of the annular metal substrate 4 and on the other side of the axis of the rotating shaft 7. Two second piezoelectric ceramics 12 are located on the lower surface of the annular metal substrate 4 and on one side of the axis of the rotating shaft 7, and the other two second piezoelectric ceramics 12 are located on the upper surface of the annular metal substrate 4 and on the other side of the axis of the rotating shaft 7. The projections of one first piezoelectric ceramic 11 and one second piezoelectric ceramic 12 on the upper and lower surfaces of the annular metal substrate 4 coincide. The piezoelectric ceramics 5 located on the upper surface of the annular metal substrate 4 have the same polarization direction, and the piezoelectric ceramics 5 located on the lower surface of the annular metal substrate 4 have the opposite polarization direction to the piezoelectric ceramics 5 located on the upper surface.

[0027] like Figure 6 As shown, the main body of the fixed retainer 2 is a semi-circular arc, and there are circular through holes at both ends of the semi-circular arc with the center in the same direction of the diameter of the semi-circular arc; a ball bearing 8 is installed in the through hole, and the ball bearing 8 is connected to the rotating shaft 7.

[0028] like Figure 7 As shown, the main body of the arc slide rail 3 is an arc with an opening. A rectangular protrusion is provided at the opening, and the protrusion is connected to the tension spring 9. By adjusting the length of the tension spring 9, the magnitude of the preload can be changed, so that the driving foot 6 of the piezoelectric vibrator abuts against the inner contour of the arc slide rail 3, thereby applying the preload.

[0029] like Figure 5 As shown, a rectangular groove is formed on the inner side of the arc section of the fixed retainer 2, and a rectangular groove is also formed on the outer side of the arc section of the arc slide rail 3. The rectangular groove on the inner side of the fixed retainer 2 and the rectangular groove on the outer side of the arc slide rail 3 fit together. Moreover, the center of the arc of the arc slide rail 3 is located on the straight line connecting the centers of the two ball bearings 8.

[0030] The control method for a squirrel-cage integrated piezoelectric actuator is as follows:

[0031] like Figures 8 to 11 As shown, when the two sets of piezoelectric ceramic sheets 5 are excited by two sets of AC signals, the ring piezoelectric oscillator 1 is simultaneously excited to produce two different vibration modes: an in-plane fourth-order longitudinal vibration mode with four peaks and troughs, and the two driving feet 6 are simultaneously at the peaks or troughs; and an out-of-plane fifth-order bending vibration mode with five peaks and troughs, and the two driving feet 6 are respectively at the peaks and troughs.

[0032] like Figure 12As shown, when two AC signals with a 90-degree time phase difference excite the two sets of piezoelectric ceramic sheets 5 respectively, the in-plane fourth-order longitudinal vibration mode and the out-of-plane fifth-order bending vibration mode of the ring piezoelectric oscillator 1 are coupled, and the two driving feet 6 generate elliptical motion with the same rotation direction but a phase difference of 180 degrees. The frictional reaction force generated by the driving feet 6 and the circular arc slide rail 3 drives the ring piezoelectric oscillator 1 to spin around its own axis. If the phase difference of the applied two-phase electrical signals is changed to -90 degrees, the ring piezoelectric oscillator 1 will move in the opposite direction.

Claims

1. A cage type moving-magnetic rotor integrated piezoelectric actuator characterized by comprising: The application relates to a ring-shaped piezoelectric vibrator (1), a fixed holder (2) and a circular arc sliding rail (3); the ring-shaped piezoelectric vibrator (1) comprises a ring-shaped metal base (4) and piezoelectric ceramics (5); a group of driving feet (6) located at the two ends of the ring-shaped metal base (4) in the diameter direction and a group of rotating shafts (7) perpendicular to the symmetric shafts of the driving feet (6) are arranged on the outer ring surface of the ring-shaped metal base (4), and the rotating shafts (7) are symmetrical about the straight line where the two driving feet (6) are located; the piezoelectric ceramics (5) comprise four first piezoelectric ceramics (11) and four second piezoelectric ceramics (12), wherein two first piezoelectric ceramics (11) are located on the upper surface of the ring-shaped metal base (4) and on one side of the axis of the rotating shaft (7), the other two first piezoelectric ceramics (11) are located on the lower surface of the ring-shaped metal base (4) and on the other side of the axis of the rotating shaft (7); two second piezoelectric ceramics (12) are located on the lower surface of the ring-shaped metal base (4) and on one side of the axis of the rotating shaft (7), and the other two second piezoelectric ceramics (12) are located on the upper surface of the ring-shaped metal base (4) and on the other side of the axis of the rotating shaft (7); the projection of one first piezoelectric ceramic (11) and one second piezoelectric ceramic (12) on the upper and lower surfaces of the ring-shaped metal base (4) is coincident; the piezoelectric ceramics (5) located on the upper surface of the ring-shaped metal base (4) have the same polarization direction, and the piezoelectric ceramics (5) located on the lower surface of the ring-shaped metal base (4) have the polarization direction opposite to that of the piezoelectric ceramics (5) on the upper surface.

2. The piezoelectric actuator according to claim 1, wherein The main body shape of the fixed holder (2) is a semicircular arc, two ends of the semicircular arc are provided with through holes with the same center in the diameter direction of the semicircular arc; ball bearings (8) are arranged in the through holes; the ball bearings (8) are connected with the rotating shafts (7).

3. The piezoelectric actuator according to claim 2, wherein The upper and lower surfaces of the ring-shaped metal base (4) are provided with four fan ring grooves (10), the positions of the fan ring grooves (10) are spaced by 90 degrees of central angle, and the piezoelectric ceramics (5) are placed in the fan ring grooves (10) one by one; the four piezoelectric ceramics (5) located on the upper surface of the ring-shaped metal base (4) are arranged equidistantly and uniformly in the circumferential range, and the four piezoelectric ceramics (5) located on the lower surface of the ring-shaped metal base (4) are also arranged equidistantly and uniformly in the circumferential range.

4. The piezoelectric actuator according to claim 3, wherein The main body shape of the circular arc sliding rail (3) is an open circular arc, a rectangular protrusion is arranged at the opening, and the protrusion is connected with a tension spring (9).

5. The piezoelectric actuator according to claim 4, wherein A rectangular groove is formed in the inner side of the middle segment of the circular arc of the fixed holder (2), a rectangular groove is also formed in the outer side of the middle segment of the circular arc of the circular arc sliding rail (3), and the rectangular groove in the inner side of the fixed holder (2) and the rectangular groove in the outer side of the circular arc sliding rail (3) are embedded with each other.

6. The piezoelectric actuator according to claim 5, wherein The center of the circular arc of the circular arc sliding rail (3) is located on the straight line where the centers of the two ball bearings (8) are connected.

7. A control method of the piezoelectric actuator according to any one of claims 1 to 6, characterized by, When the two groups of piezoelectric ceramics (5) are excited by two groups of AC signals respectively, the ring piezoelectric vibrator (1) is excited to two different vibration modes simultaneously, one is in-plane vibration mode: there are even number of wave peaks and wave troughs, and the two driving feet (6) are at the wave peak or wave trough at the same time; the other is out-of-plane vibration mode: there are odd number of wave peaks and wave troughs, and the two driving feet (6) are at the wave peak and wave trough respectively; when the two-phase AC signals with 90-degree time phase difference excite the above two groups of piezoelectric ceramics respectively, the in-plane vibration mode and the out-of-plane vibration mode of the ring piezoelectric vibrator (1) are coupled; the two driving feet (6) produce elliptical motion with the same rotation direction but with a phase difference of 180 degrees, and the driving feet (6) and the circular arc sliding rail (3) produce friction force reaction force to drive the ring piezoelectric vibrator (1) to make self-rotation around the driving ring piezoelectric vibrator (1) itself rotation shaft, when the phase difference of the above two-phase signals is changed to-90 degrees, the ring piezoelectric vibrator (1) moves reversely.

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