CN107134946A - A kind of ultralow rotating speed travelling wave supersonic motor with curved surface stator tooth - Google Patents

Abstract

A kind of ultralow rotating speed travelling wave supersonic motor with curved surface stator tooth, it is related to a kind of ultrasound electric machine, the rotating speed continuously run with solving current ultrasound electric machine is difficult to be reduced to the ultralow range of speeds, and the problem of can not avoid the harmful effect brought by frequency modulation, phase modulation and amplitude modulation mode of speed regulation to stator vibrational state, it includes flexible shaft, top nut, lower nut, pedestal, shell, upper angular contact ball bearing, lower angular contact ball bearing, rotor and stator；Top nut and lower nut are screwed in the top and bottom of flexible shaft respectively, the end face of the stator is circumferentially machined with multiple stator tooths, space between two neighboring stator tooth is teeth groove, the upper surface of multiple stator tooths is linked as an annular surface, one layer of annular friction material with the curved face contact of stator tooth is equipped with the end face of the wheel rim of rotor, the other end of stator is equipped with ring-shaped piezo ceramic layer.The present invention is used for precision actuation.

Description

An ultra-low speed traveling wave ultrasonic motor with curved stator teeth

technical field

The invention relates to an ultrasonic motor, in particular to an ultra-low speed traveling wave ultrasonic motor with curved stator teeth, and belongs to the field of piezoelectric drive technology.

Background technique

Ultrasonic motor is a new type of drive that uses the inverse piezoelectric effect of piezoelectric materials to convert electrical energy into mechanical energy. Its stator is usually composed of piezoelectric ceramics and metal elastomers. Stator elasticity is achieved by applying an AC voltage of ultrasonic frequency to piezoelectric ceramics. The excitation of mechanical vibration of the same frequency in the body, and then the particles in the driving area of the stator form a motion trajectory with a driving effect, and the output of the macroscopic motion of the rotor is realized through the friction coupling between the stator and the rotor. Since the driving frequency of the ultrasonic motor is at the ultrasonic frequency, its speed range is generally tens to thousands of revolutions per minute. The speed of the ultrasonic motor can only be reduced to a few revolutions per minute through frequency modulation, phase modulation and amplitude modulation. , It is difficult to meet the requirements of low-speed 0.5r/min or lower driving speed occasions, therefore, the development of ultra-low speed ultrasonic motor has important application value.

The publication number is CN201742324U, and the publication date is February 09, 2011. The patent name is "Rotary Traveling Wave Ultrasonic Motor", which does not use a curved tooth structure, so it is difficult to apply to ultra-low speed conditions. The publication number is CN202111634U, and the publication date is January 11, 2012. The invention patent titled "Rotary Traveling Wave Ultrasonic Motor with Nut Adjusting Preload" has a section of thread processed on the output shaft. The rotor connected to the rotating shaft is tensioned towards the stator, and the preload between the stator and the rotor is controlled by controlling the movement distance of the pre-tightening nut on the center line of the rotating shaft along the direction of the stator. It is difficult to reduce the speed to the ultra-low speed range. The publication number is CN102904482A, and the publication date is January 30, 2013. The invention patent titled "A Method for Ultra-low Speed Control of Ultrasonic Motors" uses intermittent excitation to control the operation of ultrasonic motors at ultra-low speeds, and has good speed Control performance, the way to achieve ultra-low speed is intermittent drive instead of continuous drive, which cannot avoid the adverse effects of frequency modulation, phase modulation and amplitude modulation on the vibration state of the stator.

Contents of the invention

The invention provides an ultra-low speed traveling wave ultrasonic motor with curved stator teeth, in order to solve the problem that the continuous operation speed of the current ultrasonic motor is difficult to reduce to the ultra-low speed range, and it is unavoidable that the frequency modulation, phase modulation and amplitude modulation speed regulation methods will affect the stator The problem of adverse effects brought about by the vibration state.

The technical solution adopted by the present invention to solve the above problems is: an ultra-low speed traveling wave ultrasonic motor with curved stator teeth, which includes a flexible shaft, an upper nut, a lower nut, a base, a housing, an upper angular contact ball bearing, a lower angle contact ball bearings, rotor and stator;

The casing and the base are detachably connected, the upper angular contact ball bearing is installed on the base, the lower angular contact ball bearing is installed on the casing, the flexible shaft is installed on the upper angular contact ball bearing and the lower angular contact ball bearing, the upper angular contact ball bearing is connected with the A rotor and a stator are arranged between the lower angular contact ball bearings, the rotor is arranged adjacent to the casing and installed on a flexible shaft, the stator is installed on the base, and a flexible hinge structure is processed on the shaft section of the flexible shaft between the rotor and the stator ;

The upper nut and the lower nut are respectively screwed on the upper end and the lower end of the flexible shaft. One end surface of the stator is processed with a plurality of stator teeth along the circumferential direction. The space between two adjacent stator teeth is a tooth groove, and the plurality of stator teeth The upper surface of the upper surface of the rotor is connected to form a ring-shaped curved surface. After the ring-shaped curved surface is unfolded, it becomes a curved surface waveform. The amplitude of the curved surface waveform is 0.2-50 times the amplitude of the traveling wave waveform. A layer of ring-shaped friction material, and the other end surface of the stator is laid with a ring-shaped piezoelectric ceramic layer.

The beneficial effects of the present invention are: the present invention uses curved stator teeth to adjust the speed of the traveling wave ultrasonic motor, avoiding the adverse effects on the vibration state of the stator caused by frequency modulation, phase modulation and amplitude modulation, and is a practical The new speed regulation method of the wave ultrasonic motor can break through the adjustment limit of the existing ultrasonic motor speed, can greatly reduce the speed of the ultrasonic motor, and makes the ultrasonic motor have the performance of ultra-low speed operation, and the continuous operation speed of the ultrasonic motor of the present invention can be reduced When the ultra-low speed is below 0.5r/min, it can run continuously at ultra-low speed, and is suitable for occasions that require ultra-low speed drive. Due to the small size of the curved stator tooth structure, it will not have a great impact on the stator vibration shape. At the same time, the high-frequency drive characteristics of the ultrasonic motor can be used to ensure the operation stability of the ultrasonic motor and truly realize the ultra-low speed drive performance of the ultrasonic motor. .

Description of drawings

Fig. 1 is the overall structure schematic diagram of the present invention;

Fig. 2 is a schematic diagram of a curved stator structure;

Fig. 3 is a partial schematic diagram of a sinusoidal waveform after the stator is unfolded in an embodiment;

Fig. 4 is a schematic diagram showing the combination of a cosine waveform and a square wave after the stator is unfolded in another embodiment;

Fig. 5 is a superimposed schematic diagram of a cosine waveform and a square wave in which the curved surface waveform of the stator is unfolded in another embodiment;

Fig. 6 is a partial schematic diagram of micro-holes processed at the tooth root of the stator tooth in another embodiment;

Figure 7 is three waveform state diagrams when the time is zero;

Figure 8 is a schematic diagram of three waveform states under a quarter traveling wave period;

Fig. 9 is a schematic diagram of three waveform states under 1/2 traveling wave period;

Fig. 10 is a schematic diagram of three waveform states under a three-quarter traveling wave period.

detailed description

The technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and through specific implementation methods.

In conjunction with Figures 1-6, an ultra-low speed traveling wave ultrasonic motor with curved stator teeth includes a flexible shaft 1, an upper nut 2, a lower nut 6, a base 7, a housing 10, and an upper angular contact ball bearing 4 , lower angular contact ball bearing 11, rotor 5 and stator 9;

The housing 10 and the base 7 are detachably connected, the upper angular contact ball bearing 4 is installed on the base 7, the lower angular contact ball bearing 11 is installed on the housing 10, and the flexible shaft 1 is installed on the upper angular contact ball bearing 4 and the lower angular contact ball bearing 11, a rotor 5 and a stator 9 are arranged between the upper angular contact ball bearing 4 and the lower angular contact ball bearing 11, the rotor 5 is arranged adjacent to the housing 10 and installed on the flexible shaft 1, and the stator 9 is installed on the base 7, A flexible hinge structure is processed on the shaft section of the flexible shaft 1 located between the rotor 5 and the stator 9;

The upper nut 2 and the lower nut 6 are respectively screwed on the upper end and the lower end of the flexible shaft 1, and one end surface of the stator 9 is processed with a plurality of stator teeth 9-1 along the circumferential direction, between two adjacent stator teeth 9-1 The space in the space is a tooth slot, and the upper surfaces of a plurality of stator teeth 9-1 are connected to form an annular curved surface. After the annular curved surface is unfolded, it becomes a curved surface waveform. The amplitude of the curved surface waveform is 0.2-50 times the amplitude of the traveling wave waveform. The wheel of the rotor 5 A layer of annular friction material 8 in contact with the curved surface of the stator teeth is laid on the end surface of the stator 9 , and an annular piezoelectric ceramic layer 13 is laid on the other end surface of the stator 9 .

The amplitude of the traveling wave is at the micron level, and the amplitude of the curved surface waveform of the stator teeth is also at the micron level. The curved stator tooth structure will not greatly change the mode shape of the stator, ensuring that the stator has good vibration characteristics. In addition, compared with the commonly used frequency modulation speed regulation method, the speed regulation method of this project does not affect the working frequency of the stator, and can make the stator work at the optimal driving frequency to realize the adjustment of the motor speed. Angular contact bearings are used to eliminate the clearance of the bearings, which improves the operation stability of the ultrasonic motor and enhances the load capacity of the motor. The flexible hinge structure can produce a certain deformation under the action of bending moment, can transmit torque, is free of assembly, and has no friction and wear. In order to ensure the firmness and stability of the upper angular contact ball bearing 4 and the lower angular contact ball bearing 11 , the upper end and the lower end of the flexible shaft 1 are respectively screwed with the upper retaining ring 3 and the lower retaining ring 12 .

Referring to Fig. 2, the cross section of a single stator tooth 9-1 is fan-shaped. In this way, the fan-shaped stator teeth ensure the matching with the overall structure of the stator, the widths of the stator teeth are almost the same, and the widths of adjacent tooth slots are almost the same. It is better to realize the adjustment of the motor speed.

According to different low-speed requirements, the output force of the friction interface is adjusted by superimposing different forms of curved surface waveforms and traveling wave waveforms, and then different speeds of ultrasonic motors are obtained. There are three types of curved surface waveforms:

Referring to FIG. 3 for illustration, the curved surface waveform is a sine waveform or a cosine waveform. This form is suitable for ultra-low speed working conditions.

Referring to FIG. 4, the curved surface waveform is a combination of a sine waveform and a square wave or a combination of a cosine waveform and a square wave. This form is suitable for working conditions with a slightly higher speed.

Referring to FIG. 5 for illustration, the curved surface waveform is a superposition of a cosine waveform and a square wave. This form is suitable for working conditions with a slightly higher speed and helps to improve the starting performance of the motor.

Referring to Fig. 6, in order to ensure the stability of the traveling wave, the root of the stator tooth 9-1 is processed with a microhole 9-2, and the diameter of the microhole 9-2 gradually decreases from the maximum amplitude to the minimum amplitude of the curved surface waveform. small. Microholes with different diameters are processed at the root of the stator tooth to adjust the position of the neutral layer of the stator and ensure that the traveling wave generated by the inverse piezoelectric effect of piezoelectric ceramics is not distorted.

Referring to Fig. 1, in order to improve the running stability of the motor, the flexible hinge structure is mainly composed of N circular arc grooves 1-1 processed radially on the flexible shaft 1, where N≥1. The flexible hinge structure is used to realize the self-adaptive adjustment of the contact between the rotor and the stator. The size of the flexible hinge is calculated according to the requirements of the given working conditions, which can avoid the uneven contact between the rotor and the stator due to the fixed ends of the flexible shaft. The contact of the rotor can be adaptively adjusted according to the contact situation, which increases the running stability of the motor.

Referring to Fig. 1, in order to improve the restartability of the motor and improve the use instructions of the motor, the annular friction material 8 adopts oil-containing friction material, and the oil-containing friction material includes the following in weight percentage:

Polymer matrix: 45%-80%;

Friction modifier: 10%-30%;

Carbon microtubes: 1%-30%;

The polymer matrix is any combination of polytetrafluoroethylene and polyphenylester, polyimide or bismaleimide;

The friction modifier is one or a combination of copper powder, nickel powder, copper oxide, molybdenum disulfide, graphite, nano-diamond powder, carbon fiber, glass fiber and rare earth powder.

The carbon microtube is an oil-containing carrier, which can precisely control the oil content of the friction material and improve its oil retention rate. The type of matrix material of the oil-containing material is not limited, and the friction material suitable for ultrasonic motors under different working conditions can be prepared; the friction material is also The operation of the ultrasonic motor is stable, the output torque is large, and the bonding of the stator and rotor after long-term storage is effectively avoided; the operation stability of the ultrasonic motor is improved, and the load capacity of the motor is enhanced. The friction coefficient is 0.07-0.18, and the wear rate is 1.0×10 ^-8 mm ³ /Nm-2×10 ^-8 mm ³ /Nm.

working mechanism

Taking the amplitude of the curved surface waveform of the stator tooth equal to the amplitude of the traveling wave as an example, the motion and force of the contact interface between the curved stator tooth and the rotor in one cycle are analyzed, as shown in Figure 7. W, W ₁ and W ₂ are the actual waveform of the stator surface, the traveling wave waveform and the curved surface waveform of the stator teeth, respectively. The surface waveform W ₂ of the stator tooth is fixed and does not change with time. The traveling wave waveform W ₁ passes along the positive direction of the x-axis with time. The actual waveform W of the stator surface is composed of the traveling wave waveform W ₁ and the stator tooth The surface waveform W ₂ is superimposed. The traveling wave waveform determines the motion of the stator tooth surface particles; the actual waveform determines the deformation shape of the stator tooth surface, and then determines the actual contact state between the stator and the rotor. Fig. 7 shows the states of the three waveforms at time t=0. The displacement unit of the ordinate is mm. At this time, the curved surface waveform of the stator tooth coincides with the traveling wave waveform, the actual waveform amplitude increases, the pressure in the contact area increases, and the actual contact area becomes smaller (meaning that the viscous area decreases), and the contact The frictional driving force of the interface increases. Figure 8 shows the states of the three waveforms when t=T/4, where T is the period of the traveling wave. At this time, the traveling wave waveform and the curved surface waveform of the stator teeth no longer overlap, and the actual waveform determines the contact between the stator and the rotor. In the actual contact area, there is a driving area and a counter-driving area, and the friction direction in the two areas is opposite. The range of the driving zone becomes smaller, and the frictional driving force of the contact interface becomes smaller. Figure 9 shows the states of the three waveforms when t=T/2. At this time, the traveling wave waveform and the curved surface waveform of the stator tooth cancel each other, and the actual waveform on the stator surface is a plane, and the friction driving force within one wavelength is 0 at this time. Figure 10 shows the state of the three waveforms when t=3T/4, which is similar to the state shown in Figure 8 .

It can be seen from the above analysis that by changing the annular surface structure of the stator teeth of the stator, the magnitude of the friction driving force can be controlled, and then the speed of the ultrasonic motor can be controlled. It is also possible to further reduce the speed of the motor by continuing to increase the amplitude of the curved surface waveform of the stator teeth, so that the stator generates friction in the opposite direction to the rotor in a certain period of time, and it is also possible to design two or more waveforms (such as cosine The superposition of waveform and square wave) adjusts the speed and torque of the motor. In the previous research, because the driving frequency of the ultrasonic motor is in the ultrasonic frequency band, its speed is relatively fast, and it is difficult to achieve the ultra-low speed requirement through the traditional frequency modulation, phase modulation and amplitude modulation speed regulation methods. The speed regulation through the stator surface tooth structure proposed in this project way to overcome this problem. Since the amplitude of the traveling wave is at the micron level, the amplitude of the curved surface waveform is also at the micron level. The curved stator tooth structure will not greatly change the mode shape of the stator, ensuring that the stator has good vibration characteristics. In addition, compared with the commonly used frequency modulation speed regulation method, the speed regulation method of the present invention does not affect the working frequency of the stator, and can make the stator work at the optimal driving frequency to realize the adjustment of the motor speed.

The present invention has been disclosed above with preferred implementation examples, but it is not intended to limit the present invention. Any skilled person who is familiar with the profession can use the structure and technical content disclosed above to make some The changes or modifications are equivalent implementation cases with equivalent changes, but any simple modifications, equivalent changes and modifications made to the above implementation cases according to the technical essence of the present invention without departing from the content of the technical solutions of the present invention are still The scope of the technical solutions of the present invention.

Claims (8)

1. a kind of ultralow rotating speed travelling wave supersonic motor with curved surface stator tooth, it is characterised in that：It include flexible shaft (1), on Nut (2), lower nut (6), pedestal (7), shell (10), upper angular contact ball bearing (4), lower angular contact ball bearing (11), rotor And stator (9) (5)；

Shell (10) and pedestal (7) are detachably connected, and are provided with angular contact ball bearing (4), shell (10) and are pacified on pedestal (7) Equipped with lower angular contact ball bearing (11), flexible shaft (1) is arranged on upper angular contact ball bearing (4) and lower angular contact ball bearing (11) On, be disposed with rotor (5) and stator (9) between upper angular contact ball bearing (4) and lower angular contact ball bearing (11), rotor (5) with Shell (10) is disposed adjacent and on flexible shaft (1), stator (9) is installed on pedestal (7), positioned at rotor (5) and calmly Flexible hinge structure is machined with the shaft part of flexible shaft (1) between sub (9)；

It is characterized in that：Top nut (2) and lower nut (6) are screwed in the top and bottom of flexible shaft (1), the stator respectively (9) space that end face is circumferentially machined between multiple stator tooths (9-1), two neighboring stator tooth (9-1) is teeth groove, many The upper surface of individual stator tooth (9-1) is linked as an annular surface, waveform in curved surface, the amplitude of curved surface waveform after annular surface expansion For 0.2-50 times of traveling-wave waveform amplitude, one layer with the curved face contact of stator tooth is equipped with the end face of the wheel rim of rotor (5) Annular friction material (8), the other end of stator (9) is equipped with ring-shaped piezo ceramic layer (13).

2. a kind of ultralow rotating speed travelling wave supersonic motor with curved surface stator tooth according to claim 1, it is characterised in that：It is single The cross section of individual stator tooth (9-1) is sector.

3. a kind of ultralow rotating speed travelling wave supersonic motor with curved surface stator tooth according to claim 2, it is characterised in that：Institute Curved surface waveform is stated for sinusoidal waveform or cosine waveform.

4. a kind of ultralow rotating speed travelling wave supersonic motor with curved surface stator tooth according to claim 2, it is characterised in that：Institute It is sinusoidal waveform and square wave combination or the combination of cosine waveform and square wave to state curved surface waveform.

5. a kind of ultralow rotating speed travelling wave supersonic motor with curved surface stator tooth according to claim 2, it is characterised in that：Institute State superposition of the curved surface waveform for cosine waveform and square wave.

6. a kind of ultralow rotating speed travelling wave supersonic motor with curved surface stator tooth according to claim 3, it is characterised in that：It is fixed The root portion of sub- tooth (9-1) is machined with micropore (9-2), the aperture of micropore (9-2) from curved surface waveform maximum amplitude to most small size Value direction is gradually reduced.

7. a kind of ultralow rotating speed traveling-wave ultrasonic with curved surface stator tooth according to any one of claim 1 to 6 claim Motor, it is characterised in that：Main whole circle arc groove (1-1) structure of N bars radially processed by flexible shaft (1) of flexible hinge structure Into wherein N >=1.

8. a kind of ultralow rotating speed travelling wave supersonic motor with curved surface stator tooth according to claim 7, it is characterised in that：Ring Shape friction material (8) is oil-containing friction material, and the oil-containing friction material includes by weight percentage as follows：

Polymeric matrix：45%-80%；

Friction modifier：10%-30%；

Carbon micron tube：1%-30%；

Described polymeric matrix is polytetrafluoroethylene (PTFE) and polybenzoate, polyimides or double maleic amides combinations of any one；

Described friction modifier is copper powder, nickel powder, cupric oxide, molybdenum disulfide, graphite, nano-diamond powder, carbon fiber, glass One or more of combinations in fiber and rare earth powder.