CN1667934A - Slotted Metal Square Pillar Piezoelectric Composite Ultrasonic Micromotor - Google Patents

Abstract

This invention relates to a metal square post piezoelectric compound supersonic micro-machine composed of a stator exciting vibration of supersonic sound, a rotor outputting moment or a runner and a pre-pressure unit pressing the rotor or the runner characterizing that said stator is mainly composed of a metal piezoelectric ceramic compound square post and matched blocks comprising a metal square post exciting vibration and piezoelectric ceramic plates, four slots are opened axially at the four edge angles of the post, said plates are adhered on the two or four side faces of the post polarized along the thickness direction, the surface of the plate connected with excited electrode is coated with outer electrodes for polarization and excitation.

Description

Slotted Metal Square Pillar Piezoelectric Composite Ultrasonic Micromotor

technical field

The invention belongs to the field of ultrasonic application, in particular to a structure design of a miniaturized ultrasonic motor.

Background technique

The piezoelectric ultrasonic motor is a driving mechanism made of a specific structure using the inverse piezoelectric effect of piezoelectric materials. It is generally composed of functional components such as a stator, a rotor, and a pre-pressure mechanism. It uses the inverse piezoelectric effect of piezoelectric ceramics to generate ultrasonic vibrations on the surface of the stator, and the friction between the stator and the rotor drives the rotor to move. Ultrasonic motors have the following advantages over ordinary electromagnetic motors:

1. Low speed, high torque, can directly drive the load without deceleration mechanism;

2. Small size, flexible structure, power volume ratio is 3-10 times that of electromagnetic motor;

3. Quick start and stop response, the response time is less than 1 millisecond;

4. No electromagnetic interference, nor electromagnetic interference;

5. With self-holding torque, no gear backlash, and precise positioning;

6. Quiet and noiseless operation.

Bending vibration mode ultrasonic motor is a kind of ultrasonic motor. Its structure is relatively simple compared with other ultrasonic motors. The stator is mainly composed of a piezoelectric ceramic element that excites vibration and a matching block. The transmission principle of the bending vibration modal ultrasonic motor is shown in Figure 1. The stator is in the vibration mode of circular shaking. There is a small gap between the stator 11 and the annular rotor 12. During transmission, the stator moves while bending and shaking the head. Therefore, the stator, There is tangential contact between the rotors, and the contact point moves on the outer circumference of the stator. In turn, the friction force between the stator and the rotor makes the rotor rotate in the opposite direction to the direction of movement of the contact point.

There are two excitation methods for the stator vibration of the common flexural vibration mode ultrasonic motor. The first one uses the d ₃₃ effect of piezoelectric ceramics to apply an electric field in the polarization direction to cause piezoelectric ceramics to deform along the polarization direction; the second One uses the d ₃₁ effect of piezoelectric ceramics to apply an electric field in the polarization direction to cause piezoelectric ceramics to deform vertically to the polarization direction. Figure 2 is a schematic diagram of the excitation mode and structure of the bending head ultrasonic motor using the d ₃₃ piezoelectric effect of piezoelectric ceramics. This kind of motor is relatively mature. It uses the d ₃₃ effect of piezoelectric ceramics to excite the bending vibration of the stator, thereby exciting The shaking head vibration of the stator. The polarization and excitation of the piezoelectric ceramics of the motor are shown in Figure 2(a). The piezoelectric ceramic elements used in the stator are 4 piezoelectric sheets, and the same piezoelectric sheet is divided into two halves with anti-phase polarization symmetrically in diameter. , the two piezoelectric sheets 211 passing the A-phase current and the two piezoelectric sheets 212 passing the B-phase current are vertically arranged in space, and the stator is composed of a Langevin sandwich structure. At the same time, the A-phase inputs the Sinωt signal, and the B-phase inputs the Cosωt signal. In this way, the bending vibration is excited by using a 90-degree phase difference in time and space; the structure of the bending vibration mode ultrasonic motor excited by the piezoelectric sheet is shown in Figure 2 (b), and the upper and lower matching blocks 226, 228 clamp four piezoelectric The ceramic sheet 227 forms the stator of the motor together, and the 225 placed on the stator is the rotor, and the spring 224 that applies preload is arranged in its hollow part, and the torque is output through the gear 223, and 222 is a polytetrafluoroethylene sleeve, which acts as a bearing, 221 For the washer, 229 is the main shaft.

The main advantage of the bending vibration mode ultrasonic motor is that it is easy to realize miniaturization and industrialization. Rod-shaped oscillating head ultrasonic motors have been industrialized, but the diameters of the motors are generally relatively large; their applications in mobile phones, medical and aerospace fields are still limited.

Figure 3 shows the oscillating head type ultrasonic motor with a half-circle and half-square stator invented by Kenji Uchino et al. The diameter is only 1.6 mm. Piezoelectric ceramic sheets 32 and 33 polarized along the thickness direction are pasted on the two vertical sides of the metal cylinder 31 to form a stator, as shown in FIG. 3( a ). The piezoelectric ceramic excites the oscillating movement of the stator, and drives the rotor 34 to drive the output shaft 35 to rotate. 33 is a pre-pressure adjustment spring, as shown in Figure 3(b), the electrodes 31 and 32 are sequentially fed with sinωt and cosωt signals for excitation. The d ₃₁ piezoelectric effect of piezoelectric ceramics is used to excite bending vibration on the stator.

Based on the structure in FIG. 3 , when the other two sides of the metal body 45 , that is, the four sides are all pasted with piezoelectric ceramic sheets 41 , 42 , 43 , 44 , an actuator is formed, as shown in FIG. 4 . Adding the rotor system can constitute an oscillating head type ultrasonic motor, which can obtain a larger output torque/force than the oscillating head type ultrasonic motor with the structure shown in Figure 3.

Although the piezoelectric ceramic tube and metal composite tube string scheme is conducive to the miniaturization of the structure of the ultrasonic motor. However, when the structural size of the actuator or the motor is small, the bending amplitude of the vibrator is also small, which cannot be effectively driven. In order to increase the bending amplitude, the diameter of the metal body must be reduced, which also reduces the size of the chip ceramics and reduces the output torque/force.

Contents of the invention

In order to overcome the above-mentioned problems in the prior art, the utility model proposes a slotted metal square column piezoelectric plate composite ultrasonic micromotor, which utilizes the d ₃₁ effect of piezoelectric ceramics to excite the bending vibration mode of the stator. It has the advantages of reducing the stiffness of the stator and increasing the bending amplitude without reducing the size of the patch ceramics.

The slotted metal square column piezoelectric plate composite ultrasonic micro-motor proposed by the present invention is composed of a stator that excites ultrasonic vibration, a rotor or mover that outputs torque, and a pre-pressure mechanism that pressurizes the rotor or mover. It is characterized in that the The stator is mainly composed of a metal piezoelectric ceramic composite square column and a matching block composed of a metal square column that excites vibration and a piezoelectric ceramic sheet. There are four slots along the axial direction at the four corners of the metal square column. The piezoelectric ceramic sheet is bonded on two or four sides of the metal square column and polarized along the thickness direction. The surface of the piezoelectric ceramic sheet connected to the excitation electrode is coated with an external electrode for polarization and excitation.

The metal square pillar can be a hollow square pillar or a solid square pillar.

The grooves of the metal square pillars can be in any shape such as circular grooves, rectangular grooves, special-shaped grooves or right-angled grooves.

When the metal piezoelectric ceramic composite square column adopts 2 piezoelectric ceramic sheets, the 2 piezoelectric ceramic sheets are respectively bonded to the two adjacent sides of the metal square column, and the sinωt and cosωt excitation electrical signals are respectively added (can be used in the stator Two bending vibration modes perpendicular to each other are excited on the top, and the end and middle of the stator produce elliptical vibration).

When the metal piezoelectric ceramic composite square column adopts 4 piezoelectric ceramic sheets, the 4 piezoelectric ceramic sheets are respectively bonded to the four sides of the metal square column, so that the polarization directions of the relative piezoelectric ceramic sheets are opposite (relatively In the normal direction of the metal post paste surface), the four adjacent sides are sequentially applied with sinωt, cosωt, sinωt, cosωt excitation electrical signals (two mutually perpendicular bending vibration modes can be excited on the stator, and the ends of the stator and Elliptical vibrations are generated in the middle).

When the metal piezoelectric ceramic composite square column adopts 4 piezoelectric ceramic sheets, the 4 piezoelectric ceramic sheets are bonded to the four sides of the metal square column respectively, and the polarization directions of the relative piezoelectric ceramic sheets can also be made to be the same ( Relative to the normal direction of the paste surface of the metal column), add sinωt, cosωt, -sinωt, -cosωt excitation electrical signals to the four adjacent sides in sequence (two mutually perpendicular bending vibration modes can be excited on the stator, and the stator’s Elliptical vibrations are generated at both the end and the middle).

The piezoelectric ceramic sheets can be 4 pieces, which are bonded to the four sides of the metal square column. The polarization direction of a group of relative piezoelectric ceramic sheets is the same (relative to the normal direction of the surface of the metal column pasted), and the other group is relatively opposite. The polarization direction of the piezoelectric ceramic sheet is opposite. If the four adjacent sides are sequentially applied with sinωt, cosωt, -sinωt, and cosωt excitation electrical signals, the two cosωt signals are applied to the two ceramics with opposite polarization directions. Sequentially apply sinωt, cosωt, sinωt, -cosωt excitation electrical signals, then the two sinωt signals are added to the two pieces of ceramics with opposite polarization directions (two mutually perpendicular bending vibration modes are excited on the stator, and the ends of the stator and the middle part produce elliptical vibration).

When the above-mentioned sinωt (or -sinωt) excitation signal and cosωt (or -cosωt) excitation signal are exchanged, the vibration of the bending head is reversed, and the movement of the motor is reversed.

The purpose of applying the electric field in the present invention is to excite two bending vibrations with a spatial phase difference of 90 degrees on the stator, and the two bending vibrations of the stator are synthesized into the shaking head motion of the stator. At this time, the movement locus of the points on the surface of the stator used to drive the rotor is an ellipse, so that the rotor/mover can be driven to move.

Features and effects of the present invention:

The ultrasonic motor designed in the present invention has four grooves along the axis at the edges and corners of the metal square column, which can reduce the stiffness of the stator and increase the bending amplitude without reducing the size of the patch ceramics.

The invention has the advantages that piezoelectric ceramics are easy to polarize, the polarization process is simple, the excitation electric field can be guaranteed to be perpendicular to the polarization direction, and the efficiency is high.

The invention can make the size of the motor very small, and promote the miniaturization of the ultrasonic motor; it will have broad application prospects in the fields of biology, medical treatment, micro-machinery, national defense technology and the like.

Description of drawings

Figure 1 is a schematic diagram of the transmission principle of an ultrasonic motor generally using a bending vibration mode.

Fig. 2 is the schematic diagram of the existing bending head ultrasonic motor adopting the d ₃₃ piezoelectric effect of piezoelectric ceramics;

Among them: Figure 2(a) is the polarization and excitation of piezoelectric ceramics, and Figure 2(b) is a schematic diagram of the structure of the motor.

Fig. 3 is the structural schematic diagram of the existing d ₃₁ piezoelectric effect bending head ultrasonic motor using piezoelectric ceramics;

Among them: Figure 3(a) shows the polarization and partition of piezoelectric ceramics, and Figure 3(b) shows the structure of the motor;

FIG. 4 is a schematic diagram of the structure and excitation form of the stator of the micro-motor with four-sided piezoelectric ceramic sheets evolved from the structure in FIG. 3 .

Fig. 5 is a schematic diagram of the structure and excitation form of the stator of the micro-motor of the present invention.

Among them: Figure 5(a) is a metal square column with piezoelectric ceramic sheets on all four sides and its polarization and excitation methods,

Figure 5(b) shows the slotting method of the slotted metal square column.

Fig. 6 is a schematic diagram of a structure of a double-ended shaft output motor according to Embodiment 1 of the present invention.

Fig. 7 is a schematic structural diagram of a second embodiment of the present invention - a single-ended shaft output motor.

Fig. 8 is a schematic diagram of a structure of a magnetic positioning motor according to Embodiment 3 of the present invention.

Fig. 9 is Embodiment 4 of the present invention - a structural schematic diagram of the waist and abdomen drive motor; wherein,

Figure 9(a) shows that the rotor is perpendicular to the stator, and the stator drives the rotor to rotate;

Figure 9(b) shows that the rotor is parallel to the stator, and the stator drives the rotor to rotate.

Fig. 10 is a schematic diagram of the fifth embodiment of the present invention - the structure of the end drive motor.

Detailed ways

The metal square column piezoelectric sheet composite ultrasonic micromotor of the present invention is described as follows in conjunction with the accompanying drawings and the embodiments of five kinds of motor structures respectively:

The metal square-column piezoelectric plate composite ultrasonic micro-motor proposed by the present invention consists of a stator that excites ultrasonic vibrations, a rotor (or mover) that outputs torque, and a pre-pressure mechanism that pressurizes the rotor (or mover). It is mainly composed of a piezoelectric ceramic component that excites vibration and a matching block; the piezoelectric ceramic component is a metal piezoelectric ceramic sheet composite square column composed of a metal square column with a piezoelectric ceramic element attached to the side. The structural form of the metal piezoelectric ceramic sheet composite square column is shown in Figure 5. Have four slots 52 along the axial direction at the 4 angular positions of the metal square pillar 515, and piezoelectric ceramic sheets 511, 512, 513, 514 are bonded on two or four sides of the metal square pillar (as shown in Fig. 5 ( As shown in a), it is polarized along the thickness direction, and the surface of the piezoelectric ceramic sheet connected to the excitation electrode is coated with an external electrode for polarization and excitation. The metal piezoelectric ceramic sheet composite square column can be a hollow square column or a solid square column.

The grooves formed by the above-mentioned metal square pillars can be circular grooves 521, rectangular grooves 522, special-shaped grooves 523 and right-angle grooves 524, etc., as shown in Figure 5(b). On the premise of ensuring the strength of the stator, the larger the size of the slot, the greater the flexibility of the stator and the greater the bending amplitude.

The metal piezoelectric ceramic sheet composite square column plus a matching block constitutes the stator.

Piezoelectric ceramics are polarized along the thickness direction. In the structure shown in Figure 5(a), under normal circumstances, the polarization directions of the opposite ceramic sheets (ceramic sheets 511 and 513 are opposite, and ceramic sheets 512 and 514 are opposite) should be opposite during installation, so as to reduce the design difficulty of the driving power supply , of course, can also be arbitrary;

For the stator structure shown in Figure 5(a), the way to apply the electric field is: add +sinωt excitation signal on the pole surface of ceramic sheet 511, and add cosωt excitation signal on the pole surface of ceramic sheet 512, if 513 and 511 are installed If the polarization direction is the same (relative to the normal direction of the metal post paste surface), then add the -sinωt excitation signal on the 513 polar surface. Add sinωt excitation signal on the surface. If the ceramic sheet 514 and the ceramic sheet 512 have the same polarization direction when they are installed, then add the -cosωt excitation signal on the polar surface of the ceramic sheet 514; Add a cosωt excitation signal on the pole surface of 514, and ground the metal post 515;

The sinωt (or -sinωt) excitation signal is exchanged with the cosωt (or -cosωt) excitation signal, then the vibration of the bending head is reversed, and the movement of the motor is reversed.

The purpose of applying an electric field is to excite two bending vibrations with a space phase difference of 90 degrees on the stator, and the two bending vibrations of the stator are synthesized into the shaking head motion of the stator. At this time, the trajectory of the points on the surface of the stator used to drive the rotor is an ellipse, so that the rotor can be driven to move.

Various embodiments of the ultrasonic micromotor composed of the above metal piezoelectric ceramic sheet composite square column structure are described as follows:

Embodiment 1: A micro-motor with a double-ended shaft output structure

The structure of this embodiment is shown in Figure 6. Its main features are double-ended drive and shaft output, that is, the matching blocks 63 are pasted on both ends of the metal piezoelectric ceramic composite square column 64 to form the stator, and 66 is used to paste the stator 64 and the matching block. A thin layer of glue for block 63. The rotors 62 at both ends are connected together by a shaft 68 passing through the hollow stator, a spring 61 sleeved on the shaft 68 and a fastening nut 67 . Springs are used to provide preload between the stator and rotor. The stator drives the rotor 62 to rotate through the friction layer 65 . The torque is directly output by the rotor. In actual use, the outer edge of the rotor 62 can be processed into a gear, and the torque can be output through gear transmission.

Embodiment 2 is a micro-motor with a single-ended shaft output structure

This structure is shown in Figure 7, and its main feature is that a thin rod is integrally processed (or fixed) in the middle of the stator matching block 73 as the fixed shaft 77 of the motor. The shaft and the stator matching block can be the same metal piece. The metal piezoceramic sheet composite square column 74 and the matching block 73 are glued at 76, and together serve as the stator of the motor. The rotor 72 is sleeved on the fixed shaft 77 of the stator matching block 73 and a small spring 71 sleeved on the fixed shaft 77 provides a pre-pressure between the stator and the rotor. In this motor, the main function played by the shaft 77 is to locate the rotor 72 and the small pressure spring 71 . 78 is a sliding or rolling bearing. The torque is directly output by the rotor. In actual use, the outer edge of the rotor can be processed into a gear, and the torque can be output through gear transmission. 75 is the friction interface between the stator and the rotor.

Embodiment three is the micromotor of magnetic force positioning structure

This structure is shown in Figure 8, and its main feature is that the rotor is made of magnetic steel balls 81, the metal piezoelectric ceramic sheet composite square column 83 and the concave magnetic metal matching block 82 are bonded together with superglue to form a motor stator together. . The magnetic steel ball rotor is placed in the concave surface of the metal matching block 82 . In this way, the magnetic force between the rotor and the metal matching block 82 is used as the required preload for fixing the rotor and generating friction, and the torque is directly output by the rotor.

Embodiment four is the micro-motor of waist and abdomen driving structure

The structure is shown in Figure 9, and the main feature of Figure 9(a) is that the stator can drive the rotor whose axis is perpendicular to the axis of the stator to rotate. The motor matching block 913 pasted in the middle of the metal piezoceramic composite square column 912 is connected with the rotor 915 through a friction material 914, and the composite square column 912 is fixed by a fixing mechanism 911 at its flexural node. The rotor 915 is driven by the matching block 913 to move by using the motion of the middle part of the stator (waist and abdomen), which can constitute a linear motor, and can also continue to convert the motion into the rotary motion of the rotor shaft 916. The rotary motion of the rotor shaft 925 shown in FIG. 9( b ) can also be configured, that is, the stator can drive the rotor whose axis is parallel to the axis of the stator to perform rotary motion.

Embodiment 5 is a micromotor with an end drive structure

The structure is shown in Figure 10, and its main features are: the metal piezoelectric ceramic sheet composite square column 102 directly uses the matching block 103 at the end to drive the motion of the moving part 104, which can constitute a linear motor; it can also continue to convert the motion into a rotor Rotary movement of shaft 105 . The metal piezoceramic sheet composite square column 102 is fixed on the base 101 at the other end.

Claims (10)

1. A composite ultrasonic micromotor with a slotted metal square column piezoelectric sheet, composed of a stator that excites ultrasonic vibrations, a rotor or mover that outputs torque, and a pre-pressure mechanism that pressurizes the rotor or mover. It is characterized in that the The stator is mainly composed of a metal piezoelectric ceramic composite square column and a matching block composed of a metal square column that excites vibration and a piezoelectric ceramic sheet. There are four slots along the axial direction at the four corners of the metal square column. The piezoelectric ceramic sheet is bonded on two or four sides of the metal square column and polarized along the thickness direction. The surface of the piezoelectric ceramic sheet connected to the excitation electrode is coated with an external electrode for polarization and excitation. 2. The slotted metal square pillar piezoelectric film composite ultrasonic micromotor according to claim 1, characterized in that the metal square pillar is a hollow square pillar or a solid square pillar. 3. The slotted metal square column piezoelectric film composite ultrasonic micromotor according to claim 1, characterized in that the slots opened by the metal square column are circular slots, rectangular slots, special-shaped slots or right-angle slots any of the shapes. 4. The composite ultrasonic micromotor with slotted metal square pillar piezoelectric sheet as claimed in claim 1, characterized in that two piezoelectric ceramic sheets are bonded to the two adjacent sides of the hollow metal square pillar, Add sinωt and cosωt excitation electrical signals respectively. 5. The composite ultrasonic micromotor with slotted metal square pillar piezoelectric sheet as claimed in claim 1, characterized in that four piezoelectric ceramic sheets are bonded to the four sides of the metal square pillar. When the polarization direction of the piezoelectric ceramic sheet is opposite, the four adjacent sides are sequentially applied with sinωt, cosωt, sinωt, cosωt excitation electric signal; when the opposite piezoelectric ceramic sheet has the same polarization direction, the four adjacent sides are sequentially applied with sinωt, cosωt, -sinωt, -cosωt excite electrical signals. 6. The composite ultrasonic micromotor with slotted metal square pillar piezoelectric sheet as claimed in claim 1, characterized in that four piezoelectric ceramic sheets are bonded to the four sides of the metal square pillar, and one group is opposite to each other. The polarization direction of the piezoelectric ceramic sheets is the same, and the polarization direction of the opposite piezoelectric ceramic sheet is opposite. When the four adjacent sides are sequentially applied with sinωt, cosωt, -sinωt, cosωt excitation electrical signals, the two cosωt signals Applied on two pieces of ceramics with opposite polarization directions, when sinωt, cosωt, sinωt, -cosωt excitation electrical signals are applied in sequence, two sinωt signals are added to two pieces of ceramics with opposite polarization directions. 7. The slotted metal square column piezoelectric plate composite ultrasonic micro-motor according to claim 1, 2, 3, 4, 5 or 6, characterized in that the rotor adopts magnetic steel balls, and the The stator is composed of metal piezoelectric ceramic sheet composite square column and a concave magnetic metal matching block combined on its end face. The magnetic steel ball rotor is placed in the concave surface of the metal matching block. The magnetic force between the rotor and the matching block is used for The preload required to fix the rotor and generate friction, and the torque is directly output by the rotor. 8. The slotted metal square column piezoelectric plate composite ultrasonic micromotor according to claim 1, 2, 3, 4, 5 or 6, characterized in that the two metal piezoelectric ceramic composite square columns The stator is formed by pasting matching blocks at the end, and the shaft passing through the hollow stator is also included. The pre-pressure mechanism adopts a spring. The spring on the shaft and the fastening nut are integrated with the stator; the torque is directly output by the rotor. 9. The slotted metal square column piezoelectric sheet composite ultrasonic micro-motor according to claim 1, 2, 3, 4, 5 or 6, characterized in that the matching block uses a thin rod in the middle as a The matching block of the fixed shaft of the motor, the pre-pressure mechanism adopts a spring sleeved on the fixed shaft, the rotor is sleeved on the fixed shaft of the matching block and a small spring provides the pre-pressure between the stator and the rotor; the torque is determined by The rotor is output directly. 10. The slotted metal square column piezoelectric plate composite ultrasonic micro-motor according to claim 1, 2, 3, 4, 5 or 6, characterized in that it also includes a fixing mechanism for fixing the stator, and the matching The block is pasted on the middle of the metal piezoelectric ceramic composite square column, and the matching block is connected with the rotor through a friction material layer, and the movement of the middle part of the stator is driven by the matching block to form a linear motor or converted into the rotational motion of the rotor shaft.

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