A four-channel piezoelectric servo with controllable driving force

Abstract

The present invention discloses a four-channel piezoelectric servo with controllable driving force, which belongs to the field of piezoelectric actuators. The driving force between the stator and the rotor of the piezoelectric servo is changed by bending deformation of axially pre-compressed simply-supported bimorphs, thereby realizing independent actuation of four rudders. The present invention provides driving force through a frame structure composed of four rods with ceramic sheets attached as a stator, driving the rotor and the rudder surface to rotate. A piezoelectric bimorph is installed between the rotor and the base, and the pre-pressure and friction between the stator and the rotor are changed by deformation of the bimorph, thereby solving the problem that the four rudders must be actuated simultaneously when driven by the same stator, and realizing that the four rudders can be controlled separately. The present invention uses axially pre-compressed simply-supported bimorphs as a pre-pressure fine-tuning mechanism to change the driving force between the stator and the rotor, has a simple structure, is easy to implement, improves the electromechanical conversion efficiency, solves the problem that the piezoelectric actuator uses one stator and cannot realize multi-channel independent actuation, and realizes multi-channel independent actuation.

Description

Technical Field

[0001] The invention belongs to the field of piezoelectric actuators, and in particular relates to a four-channel piezoelectric servo with controllable driving force. Background Art

[0002] Various actuators designed and made of piezoelectric ceramics usually have many advantages such as fast response, high bandwidth, and good control accuracy, and these advantages are very consistent with the design requirements of servos. Therefore, more and more designers tend to apply piezoelectric ceramics to the integrated design of servos. Due to the flexibility and diversity of the design of piezoelectric actuators, researchers have proposed various piezoelectric servos. Although these servos are of various types, most of them are less mature, and due to the limitation of design size, most piezoelectric servos are difficult to achieve multi-channel individual control. The design of integrating multiple small piezoelectric actuators in the same servo can achieve multi-channel individual control, but due to the limitation of the size of the stator and rotor of the small actuator, this servo cannot produce a large enough output torque, so it is not suitable in many occasions. Summary of the invention

[0003] The present invention provides a four-channel piezoelectric servo with controllable driving force. The servo utilizes the bending of a piezoelectric bimorph to change the pre-stress between a stator and a rotor, so that the same stator provides different driving forces to multiple groups of rotors, thereby realizing the individual control of multiple channels.

[0004] To achieve the above objectives, the present invention adopts the following technical solutions:

[0005] A four-channel piezoelectric servo with controllable driving force, comprising: a stator part, a rotor part and a pre-pressure control part; the stator part comprises: a stator seat 2, a piezoelectric ceramic sheet 12, the main body of the stator seat 2 is surrounded by four rods, the middle part of the rod is a rectangular parallelepiped structure 2.3, the two ends of the rod are cylindrical structures 2.1, two adjacent rods are connected by a semicircular structure 2.2, the top of the outer circular surface of the semicircular structure 2.2 is provided with a spherical groove 2.2.1 for applying pre-pressure, and the inner circular surface of the semicircular structure is a friction driving surface 2.2.2; there are eight piezoelectric ceramic sheets 12, each two in a group, respectively adhered to the upper and lower surfaces of the rectangular parallelepiped structure of the stator seat 2;

[0006] The rotor part includes an output shaft 9, a bearing 10 and a rudder blade 8. The output shaft 9 is a columnar structure with thin ends and a thick middle part. The outer cylindrical surface of the thin columnar structure at both ends is the bearing inner ring mounting surface 9.2, and the outer cylindrical surface of the thick columnar structure in the middle is a friction contact surface 9.3, which is in close contact with the friction driving surface 2.2.2 of the stator seat 2. A square groove 9.1 is opened on the side surface of the end of the output shaft 9; two bearings 10 are divided into a group, and the inner rings are respectively mounted on the bearing inner ring mounting surface 9.2; one end of the rudder blade 8 is a square sheet structure, and the other end face is provided with a square connecting rod 8.1, and the size of the square connecting rod 8.1 is consistent with the size of the square groove 9.1;

[0007] The preload control unit comprises an upper pressure plate 1, a piezoelectric dual-chip 3, an elastic gasket 4, a lower base 5, a small ball 6, a bearing support 7, and an adjustment gasket 11; the lower base 5 is a square frame structure, and the upper end faces of the four sides of the square frame are provided with dual-chip mounting grooves 5.1, and the long sides of the dual-chip mounting grooves 5.1 are respectively provided with upper pressure plate connecting surfaces 5.3, and screw connecting holes 5.2 are provided on the upper pressure plate connecting surfaces 5.3, and the short sides of the dual-chip mounting grooves 5.1 are respectively provided with elastic gasket mounting surfaces 5.4; through holes 1.2 are provided on the inner side surfaces of both sides of the upper pressure plate 1, and a semicircular concave ball mounting hole 1.3 is provided on the inner side of the upper plate, and the upper pressure plate 1 is installed on the lower base 5, and the square connecting rod 8.1 on the end face of the rudder blade 8 passes through the side of the upper pressure plate 1 The through hole 1.2 is installed in the square groove 9.1 of the output shaft 9; the piezoelectric dual chip 3 is composed of a piezoelectric ceramic layer 3.1 and a substrate layer 3.2. The piezoelectric ceramic layer 3.1 is two layers, and the substrate layer 3.2 is located in the middle of the two piezoelectric ceramic layers 3.1. The piezoelectric dual chip 3 is pasted on the dual chip mounting groove 5.1 of the lower base 5; the bearing support 7 is installed between the piezoelectric dual chip 3 and the output shaft 9 to provide support for the bearing 10. The piezoelectric dual chip 3 deforms and pushes the bearing support 7 to change the pre-pressure and friction between the friction driving surface 2.2.2 and the friction contact surface 9.3, thereby making the driving force controllable; the small ball 6 is installed between the ball mounting hole 1.3 and the spherical groove 2.2.1 to apply pre-pressure between the stator part and the rotor part.

[0008] In the above-described structure, a threaded hole 1.1 is provided on the bottom surface 1.4 of the upper pressure plate, and the bottom surface 1.4 of the upper pressure plate is in contact with the upper pressure plate connecting surface 5.3. The upper pressure plate 1 is connected to the lower base plate 5 by screws, and an adjustment gasket 11 is placed on the connecting surface to adjust the size of the initial preload between the stator and the rotor as needed. The elastic gasket 4 is installed on the elastic gasket mounting surface 5.4 of the lower base 5 to apply axial preload to the piezoelectric dual chip 3, thereby increasing its electromechanical coupling efficiency; the bearing support 7 is installed between the piezoelectric dual chip 3 and the output shaft 9, and the piezoelectric dual chip is deformed to push the bearing support 7, thereby changing the preload and friction force between the friction drive surface 2.2.2 and the friction contact surface 9.3, thereby making the driving force controllable. Consider whether it is necessary to add friction material between the friction drive surface 2.2.2 and the friction contact surface 9.3 according to the actual working environment.

[0009] Beneficial effects: The present invention provides a four-channel piezoelectric servo with controllable driving force, which uses a piezoelectric ceramic stator to drive four groups of rudders to produce deflection, and fine-tunes the pre-pressure between the stator and rotor through four groups of piezoelectric bimorphs, so that the four groups of rudders can be actuated separately. Piezoelectric materials themselves have the characteristics of fast response. The present invention applies piezoelectric materials to the integrated design of the four-channel servo, which can achieve millisecond-level response, thereby enhancing the controllability of the entire servo system; the entire mechanism adopts a stator to drive multiple rotors. Compared with the servo system driven by multiple stators, the stator size of the single stator drive can be maximized, thereby increasing the output torque. The bending deformation of four piezoelectric bimorphs is used to fine-tune the pre-pressure between the stator and rotor, so that multiple groups of rudders can be actuated separately, solving the problem that multiple groups of rudders cannot be precisely controlled separately when driven by a traditional single stator. In addition, the servo involved in the present invention is also insensitive to magnetic fields and does not generate magnetic fields; has good speed and position control performance and high precision; has a high control bandwidth; has relatively small power consumption; the shape can be arbitrarily designed according to user requirements; and has the advantages of low vibration and noise and stable operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 is a schematic diagram of the deformation of a simply supported bimorph under axial precompression;

[0011] Figure 2 It is a schematic diagram of the overall structure of the present invention;

[0012] Figure 3 It is a schematic diagram of the structure of the stator part of the present invention;

[0013] Figure 4 It is a schematic diagram of the lower base structure of the present invention;

[0014] Figure 5 Schematic diagram of the rotor structure of the present invention;

[0015] Figure 6 It is a schematic diagram of the upper pressing plate portion of the present invention;

[0016] Figure 7 It is a schematic diagram of the driving mode of the present invention;

[0017] In the figure, 1 is an upper pressure plate, 1.1 is a threaded hole, 1.2 is a through hole, 1.3 is a ball mounting hole, 1.4 is the bottom surface of the upper pressure plate, 2 is a stator seat, 2.1 is a cylindrical structure, 2.2 is a semicircular structure, 2.2.1 is a spherical groove, 2.2.2 is a friction driving surface, 2.3 is a rectangular parallelepiped structure, 3 is a piezoelectric dual crystal, 3.1 is a piezoelectric ceramic layer, 3.2 is a substrate layer, 4 is an elastic gasket, 5 is a lower base, 5.1 is the dual crystal mounting groove, 5.2 is the screw connection hole, 5.3 is the upper pressure plate connection surface, 5.4 is the elastic gasket mounting surface, 6 is the small ball, 7 is the bearing support, 7.1 is the bearing outer ring mounting surface, 8 is the rudder, 8.1 is the square connecting rod, 9 is the output shaft, 9.1 is the square groove, 9.2 is the bearing inner ring mounting surface, 9.3 is the friction contact surface, 10 is the bearing, 11 is the adjustment gasket, and 12 is the piezoelectric ceramic sheet. DETAILED DESCRIPTION

[0018] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments:

[0019] like Figure 2 As shown, a four-channel piezoelectric servo with controllable driving force includes: a stator part, a rotor part and a pre-pressure control part; the stator part includes: a stator seat 2 and a piezoelectric ceramic sheet 12; Figure 3 As shown, the main body of the stator seat 2 is composed of four rod-like structures, the middle of the rod-like structure is a rectangular parallelepiped structure 2.3, the two ends of the rectangular parallelepiped structure are cylindrical structures 2.1, and every two rods are connected by a semicircular structure 2.2. The outer surface of the semicircular structure 2.2 is provided with a spherical groove 2.2.1 for applying pre-pressure, and the inner surface of the semicircular structure is a friction driving surface 2.2.2; there are eight piezoelectric ceramic sheets 12, each of which is a group of two and is respectively pasted on the upper and lower surfaces of the rectangular parallelepiped structure of the stator seat 2;

[0020] like Figure 5 As shown, the rotor part includes an output shaft 9, a bearing 10 and a rudder blade 8. The output shaft 9 is a columnar structure with thin ends and a thick middle part. The outer cylindrical surface in the middle is a friction contact surface 9.3, which is in close contact with the friction drive surface 2.2.2 of the stator seat 2. It can be considered whether it is necessary to add friction material between the friction drive surface 2.2.2 and the friction contact surface 9.3 according to the actual working environment; under the excitation of the piezoelectric ceramic plate 12, the stator seat 2 causes the friction drive surface 2.2.2 to move, and drives the friction contact surface 9.3 through friction force, so that the output shaft 9 generates circumferential motion. When the rod-shaped structure on the left side of the semicircular structure 2.2 generates bending vibration and the rod-shaped structure on the right side generates longitudinal vibration, the following will be generated: Figure 7The driving force shown in the figure limits the axial and radial displacement of the rotor through the bearing 10, and the output shaft will produce counterclockwise circumferential motion under the action of the driving force; when the rod-like structure on the left produces longitudinal vibration and the rod-like structure on the right produces bending vibration, the output shaft will produce clockwise circumferential motion under the action of the driving force; a square groove 9.1 is opened at the end of the output shaft 9; two bearings 10 are divided into a group, and the inner rings are respectively installed on the bearing inner ring mounting surface 9.2 of the output shaft 9, and the outer rings are installed on the bearing outer ring mounting surface 7.1 of the bearing support 7; a square connecting rod 8.1 is arranged on the end surface of the rudder blade 8, and the connecting rod 8.1 passes through the through hole 1.2 on the upper pressure plate 1 and is installed in the square groove 9.1 of the output shaft 9;

[0021] The pre-pressure control unit includes an upper pressure plate 1, a piezoelectric bimorph 3, an elastic gasket 4, a lower base 5, a small ball 6, a bearing support 7 and an adjustment gasket 11; Figure 4 As shown, the lower base 5 is a square frame structure, and the upper end is provided with a dual-chip mounting groove 5.1, a screw connection hole 5.2, an upper pressure plate connection surface 5.3 and an elastic gasket mounting surface 5.4; Figure 6 As shown, the upper pressure plate 1 is provided with a threaded hole 1.1 at the bottom, a through hole 1.2 at the side, and a semicircular concave surface, i.e., a ball mounting hole 1.3, at the inner side of the upper plate; the upper pressure plate 1 is installed on the lower base 5, the bottom surface 1.4 of the upper pressure plate contacts the upper pressure plate connecting surface 5.3 on the lower base 5, the upper pressure plate 1 is connected to the lower base plate 5 by screws, and an adjusting gasket 11 is placed on the connecting surface as needed to adjust the size of the initial preload between the stator and the rotor, the square connecting rod 8.1 at the end face of the rudder blade 8 passes through the through hole 1.2 on the side face of the upper pressure plate 1 and is installed in the square groove 9.1 of the output shaft 9; as shown Figure 1 As shown, the piezoelectric bimorph 3 is composed of a piezoelectric ceramic layer 3.1 and a substrate layer 3.2. The piezoelectric ceramic layer 3.1 is two layers, and the substrate layer 3.2 is located in the middle of the two piezoelectric ceramic layers 3.1. The piezoelectric bimorph 3 is installed on the bimorph installation groove 5.1 of the lower base 5, and the elastic gasket 4 is installed on the elastic gasket installation surface 5.4 of the lower base 5. An axial pre-pressure is applied to the piezoelectric bimorph 3 to increase its electromechanical conversion coefficient. When the piezoelectric bimorph 3 is energized, the piezoelectric bimorph 3 will generate the following Figure 1 The deformation shown changes the pressure between the friction drive surface 2.2.2 and the friction contact surface 9.3, thereby changing the rotation speed of the four channels and realizing the separate control of the four channels; the bearing support 7 is installed between the piezoelectric dual chip 3 and the output shaft 9 to provide support for the bearing 10; the small ball 6 is installed between the upper pressure plate 1 and the stator seat 2 to apply pre-pressure between the stator part and the rotor part.

[0022] When working, firstly, voltage is applied to the 4 groups (8 pieces) of piezoelectric ceramic sheets 12 on the stator seat 2. The stator seat 2 is a quadrilateral structure. By applying voltages with the same phase to each group of piezoelectric ceramic sheets 12 on the opposite sides, the corresponding rectangular parallelepiped structure 2.3 generates longitudinal vibration, and each group of piezoelectric ceramic sheets 12 on the other pair of sides is applied with a voltage with a certain phase difference to generate a bending vibration of the corresponding rectangular parallelepiped structure 2.3, thereby generating a driving force through the friction driving surface 2.2.2 inside the semicircular structure 2.2 to drive the four output shafts 9 to rotate. By adopting the same frequency but different phase power supply mode for the 8 pieces (4 groups) of piezoelectric ceramic sheets 12, the four rudder blades 8 can generate rotational motion in different directions. By applying different peak-to-peak voltages to the four piezoelectric bimorphs 3, the four piezoelectric bimorphs 3 can generate bending moments of different magnitudes, thereby generating thrusts of different magnitudes between the stator and rotor to change the magnitude of the pressure between the stator and rotor, and then changing the rotation speed of the output shaft 9, and realizing the individual control of the rotation speed of the four rudder blades 8.

[0023] The above are only preferred embodiments of the present invention, which will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be pointed out that for those skilled in the art, without departing from the concept of the present invention, several modifications and improvements made belong to the protection scope of the present invention.

Claims

1. A four-channel piezoelectric servo with controllable driving force, characterized in that: include: A stator part, a rotor part and a pre-pressure control part; the stator part comprises: a stator seat (2), a piezoelectric ceramic sheet (12); the main body of the stator seat (2) is surrounded by four rods, the middle part of the rod is a rectangular parallelepiped structure (2.3), the two ends of the rod are cylindrical structures (2.1), two adjacent rods are connected by a semicircular structure (2.2), the top of the outer circular surface of the semicircular structure (2.2) is provided with a spherical groove (2.2.1) for applying pre-pressure, and the inner circular surface of the semicircular structure is a friction driving surface (2.2.2); there are eight piezoelectric ceramic sheets (12), two in a group, and they are respectively adhered to the upper and lower surfaces of the rectangular parallelepiped structure of the stator seat (2); The rotor part comprises an output shaft (9), a bearing (10) and a rudder blade (8); the output shaft (9) is a columnar structure with thin ends and a thick middle part; the outer cylindrical surface of the columnar structure with thin ends is a bearing inner ring mounting surface (9.2); the outer cylindrical surface of the columnar structure with a thick middle part is a friction contact surface (9.3) which is in close contact with a friction driving surface (2.2.2) of a stator seat (2); a square groove (9.1) is provided on the side surface of the end of the output shaft (9); two bearings (10) are grouped together, and the inner rings are respectively mounted on the bearing inner ring mounting surfaces (9.2); one end of the rudder blade (8) is a square sheet structure, and the other end face is provided with a square connecting rod (8.1); the size of the square connecting rod (8.1) matches the size of the square groove (9.1); The preload control unit comprises an upper pressure plate (1), a piezoelectric dual chip (3), an elastic gasket (4), a lower base (5), a small ball (6), a bearing support (7), and an adjustment gasket (11); the lower base (5) is a square frame structure, and the upper end faces of the four sides of the square frame are provided with dual chip mounting grooves (5.1), the long sides of the dual chip mounting grooves (5.1) are respectively provided with upper pressure plate connecting surfaces (5.3), and the short sides of the dual chip mounting grooves (5.1) are respectively provided with elastic gasket mounting surfaces (5.4); through holes (1.2) are provided on the inner side surfaces of the two sides of the upper pressure plate (1), and a semicircular concave ball mounting hole (1.3) is provided on the inner side of the upper plate. The upper pressure plate (1) is installed On the lower base (5), a square connecting rod (8.1) on the end face of the rudder blade (8) passes through a through hole (1.2) on the side of the upper pressure plate (1) and is installed in a square groove (9.1) of the output shaft (9); the piezoelectric bimorph (3) is composed of a piezoelectric ceramic layer (3.1) and a substrate layer (3.2), the piezoelectric ceramic layer (3.1) is two layers, the substrate layer (3.2) is located in the middle of the two layers of piezoelectric ceramic layers (3.1), and the piezoelectric bimorph (3) is adhered to the bimorph installation groove (5.1) of the lower base (5); the bearing support (7) is installed between the piezoelectric bimorph (3) and the output shaft (9), and the small ball (6) is installed between the ball installation hole 1.3 and the spherical groove (2.2.1); The bearing support (7) is installed between the piezoelectric bimorph (3) and the output shaft (9). The piezoelectric bimorph (3) deforms to push the bearing support (7), thereby changing the pre-pressure and friction force between the friction driving surface (2.2.2) and the friction contact surface (9.3).

2. The four-channel piezoelectric servo with controllable driving force according to claim 1, characterized in that: The piezoelectric servo comprises a threaded hole (1.1) provided on the bottom surface (1.4) of an upper pressure plate, a screw connection hole (5.2) provided on the upper pressure plate connection surface (5.3), the upper pressure plate bottom surface (1.4) is in contact with the upper pressure plate connection surface (5.3), and the upper pressure plate (1) is connected to the lower base plate (5) by means of screws passing through the threaded hole (1.1) and the screw connection hole (5.2).

3. The four-channel piezoelectric servo with controllable driving force according to claim 2, characterized in that: Place an adjustment gasket (11) between the bottom surface (1.4) of the upper pressure plate and the connecting surface (5.3) of the upper pressure plate as required.

4. The four-channel piezoelectric servo with controllable driving force according to claim 1, characterized in that: The elastic gasket (4) is mounted on the elastic gasket mounting surface (5.4) of the lower base (5).

5. The four-channel piezoelectric servo with controllable driving force according to claim 1, characterized in that: Add friction material between the friction driving surface (2.2.2) and the friction contact surface (9.3) as required.

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