Hollow rotating piezoelectric motor based on six-phase drive and its working method

Abstract

The present invention discloses a hollow rotary piezoelectric motor based on six-phase drive and its operating method. The motor comprises a rotor, a first bearing, a second bearing, a housing, a base, a stator, and a piezoelectric drive module. The stator comprises a fixed ring, three fixed seats, three connecting rods, and three drive feet. The piezoelectric drive module comprises six piezoelectric bimorphs. By controlling the timing and frequency of the six piezoelectric bimorphs, the present invention enables the rotor to achieve bidirectional, ultra-high-precision rotational motion, enabling high torque at low speeds and high-precision rotation at high speeds. The present invention has high reliability, high output torque, and high precision, and can be widely used in fields such as precision optics, aerospace, mechanical manufacturing, and medical equipment.

Description

Technical Field

[0001] The present invention relates to the field of piezoelectric precision drive technology, and in particular to a six-phase driven hollow rotary piezoelectric motor and a working method thereof. Background Art

[0002] The rotary ultrasonic motor is a drive based on the piezoelectric effect, ultrasonic vibration, and friction coupling. Due to its fast response speed, high precision, and large mass-torque ratio, it has extremely wide applications in fields such as mechanical manufacturing. However, the stator structure is often unable to pass through optical beams and precision robotic arms, which greatly limits the scope of application of rotary ultrasonic motors. Due to its unique hollow structure, the hollow ultrasonic motor can be used in fields that require hollow structures, such as precision optics and medical devices. However, the existing hollow rotary ultrasonic motor structure and drive signal are relatively complex, and the input voltage signal wave frequency range is limited, which poses a challenge to the simplified design of piezoelectric drive. Therefore, how to address the problems of the complex structure and complex drive signal of the existing hollow rotary ultrasonic motor, and how to achieve macro-micro drive fusion based on the simplified design of the hollow rotary ultrasonic motor structure while meeting the input voltage frequency from low to high and the stator in non-resonant mode and resonant mode has become a difficult problem that needs to be studied in the industry. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to address the defects involved in the background technology and provide a hollow rotating piezoelectric motor based on a six-phase drive mode and a working method thereof.

[0004] The present invention adopts the following technical solutions to solve the above technical problems:

[0005] A hollow rotary piezoelectric motor based on a six-phase drive, comprising a rotor, a first bearing, a second bearing, a housing, a base, a stator and a piezoelectric drive module;

[0006] The rotor is a hollow cylinder with two ends open. The first bearing is a deep groove ball bearing and the second bearing is a thrust bearing.

[0007] The housing is fixed to the base; the outer ring of the first bearing is fixedly connected to the housing, and the inner ring is coaxially fixedly connected to the outer wall of the rotor; the lower ring of the second bearing is fixedly connected to the base, and the upper ring is coaxially fixedly connected to the lower end of the bearing, so that the rotor can rotate freely relative to the base;

[0008] The stator comprises a fixing ring, three fixing seats, three connecting rods and three driving feet;

[0009] The fixing ring is a hollow cylinder with two ends open; the three fixing seats are evenly arranged on the outer wall of the fixing ring and are fixedly connected to the base, so that the fixing ring is located inside the rotor and is coaxial with the rotor;

[0010] The three connecting rods are evenly arranged circumferentially between the fixing ring and the rotor, with one end of each being fixedly connected to the outer wall of the fixing ring and the other end being fixedly connected to the three driving feet in a one-to-one correspondence; the three driving feet are all in contact with the inner wall of the rotor; the three fixing seats and the three connecting rods divide the fixing ring into six equal parts, and the first fixing seat is located between the first connecting rod and the second connecting rod;

[0011] Both sides of the three fixing seats and the three driving feet are provided with dovetail grooves;

[0012] The piezoelectric driving module includes six piezoelectric bimorphs, which are respectively arranged between the first driving foot and the first fixing seat, the first fixing seat and the second driving foot, the second driving foot and the second fixing seat, the second fixing seat and the third driving foot, the third driving foot and the third fixing seat, and the third fixing seat and the first driving foot; one end of the piezoelectric bimorph is against the dovetail groove on the corresponding driving foot, and the other end is against the dovetail groove on the corresponding fixing seat; the six piezoelectric bimorphs are simultaneously protruded inward or outward;

[0013] The six piezoelectric bimorphs are coplanar, and the plane where they are located is perpendicular to the rotation axis of the rotor;

[0014] The piezoelectric ceramic sheets on both sides of the six piezoelectric bimorphs are polarized along their thickness directions, with the polarization directions facing inward or outward at the same time.

[0015] As a further optimization solution of the hollow rotary piezoelectric motor based on six-phase drive of the present invention, the three driving feet are all made of flexible materials.

[0016] As a further optimization solution of the hollow rotary piezoelectric motor based on six-phase drive of the present invention, the outer sides of the three driving feet are provided with a friction layer made of ceramic material to improve friction performance and wear resistance.

[0017] The present invention also discloses a working method of the hollow rotating piezoelectric motor based on six-phase drive, comprising the following steps:

[0018] A) If the rotor needs to be driven in forward direction:

[0019] Voltage signal waves u1, u2, u3, u4, u5, and u6 with the same signal amplitude and frequency but different phases are input to the first to sixth piezoelectric bimorphs. The phases of the electrical signals u1, u2, u3, u4, u5, and u6 differ by 60 degrees in sequence. The two ends of the six piezoelectric bimorphs generate longitudinal tensile forces with different time phase differences, causing the three driving feet to produce positive elliptical motion. The running trajectories and driving directions of the driving surfaces of the three driving feet are completely consistent, with only a time phase difference. Under the coordinated action of the three driving feet, the rotor obtains continuous positive output torque.

[0020] B) If the rotor needs to be driven in the reverse direction:

[0021] Voltage signal waves u1, u2, u3, u4, u5, and u6 with the same signal amplitude and frequency but different phases are input to the first to sixth piezoelectric bimorphs. The electrical signals of u6, u5, u4, u3, u2, and u1 differ by 60° respectively. Longitudinal tensile forces with different time phase differences are generated at both ends of the six piezoelectric bimorphs, causing the three driving feet to produce opposite elliptical motions. The running trajectories and driving directions of the driving surfaces of the three driving feet are completely consistent, with only a time phase difference. Under the coordinated action of the three driving feet, the rotor obtains continuous output torque in the reverse direction.

[0022] Compared with the prior art, the present invention adopts the above technical solution and has the following technical effects:

[0023] 1. This invention adopts a unique hollow structure and, through the combination of three piezoelectric drive modules, streamlines the design of a six-phase drive hollow rotary piezoelectric motor structure. It is suitable for fields requiring hollow structures, such as precision optics and medical equipment.

[0024] 2. Since the present invention adopts a piezoelectric dual chip as the excitation source, the piezoelectric dual chip and the driving foot are non-fixedly matched and are embedded in the dovetail grooves of the driving foot and the positioning foot. Therefore, its response speed is fast and the accuracy is high, and its performance can be adjusted by changing the input frequency, voltage and driving mode.

[0025] 3. The present invention is provided with three groups of piezoelectric drive modules that cooperate with each other. By adjusting the amplitude and frequency of the input voltage, the ultrasonic motor can be switched between the resonant mode and the non-resonant mode, realizing macro-micro fusion drive. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a top view of the present invention;

[0027] Figure 2 is a cross-sectional view of the present invention;

[0028] Figure 3 It is a schematic structural diagram of the stator and the piezoelectric drive module in the present invention;

[0029] Figure 4 Schematic diagram of the six-phase drive signal when the rotor is driven to rotate in the forward direction;

[0030] Figure 5 Schematic diagram of the six-phase drive signal when driving the rotor to rotate in the reverse direction of the present invention;

[0031] Figure 6 This is a deformation displacement cloud diagram of the stator when the rotor is driven to rotate in the forward direction;

[0032] Figure 7 It is a deformation displacement cloud diagram of the stator when the rotor is driven to rotate in the reverse direction according to the present invention.

[0033] In the figure, 1-housing, 2-rotor, 3-stator, 4-base, 5-first bearing, 6-second bearing, 7-fixing ring, 8-driving foot, 9-fixing seat, 10-connecting rod, 11-first piezoelectric bimorph. DETAILED DESCRIPTION

[0034] In order to enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention is further described in detail below with reference to the accompanying drawings:

[0035] The present invention can be implemented in many different forms and should not be considered to be limited to the embodiments described herein. On the contrary, these embodiments are provided to make this disclosure thorough and complete and will fully convey the scope of the invention to those skilled in the art. In the accompanying drawings, components are enlarged for clarity.

[0036] like Figure 1 、 Figure 2 As shown, the present invention discloses a hollow rotary piezoelectric motor based on six-phase drive, comprising a rotor, a first bearing, a second bearing, a housing, a base, a stator and a piezoelectric drive module;

[0037] The rotor is a hollow cylinder with two ends open. The first bearing is a deep groove ball bearing and the second bearing is a thrust bearing.

[0038] The housing is fixed to the base; the outer ring of the first bearing is fixedly connected to the housing, and the inner ring is coaxially fixedly connected to the outer wall of the rotor; the lower ring of the second bearing is fixedly connected to the base, and the upper ring is coaxially fixedly connected to the lower end of the bearing, so that the rotor can rotate freely relative to the base;

[0039] like Figure 3 As shown, the stator comprises a fixing ring, three fixing seats, three connecting rods and three driving feet;

[0040] The fixing ring is a hollow cylinder with two ends open; the three fixing seats are evenly arranged on the outer wall of the fixing ring and are fixedly connected to the base, so that the fixing ring is located inside the rotor and is coaxial with the rotor;

[0041] The three connecting rods are evenly arranged circumferentially between the fixing ring and the rotor, with one end of each being fixedly connected to the outer wall of the fixing ring and the other end being fixedly connected to the three driving feet in a one-to-one correspondence; the three driving feet are all in contact with the inner wall of the rotor; the three fixing seats and the three connecting rods divide the fixing ring into six equal parts, and the first fixing seat is located between the first connecting rod and the second connecting rod;

[0042] Both sides of the three fixing seats and the three driving feet are provided with dovetail grooves;

[0043] The piezoelectric driving module includes six piezoelectric bimorphs, which are respectively arranged between the first driving foot and the first fixing seat, the first fixing seat and the second driving foot, the second driving foot and the second fixing seat, the second fixing seat and the third driving foot, the third driving foot and the third fixing seat, and the third fixing seat and the first driving foot; one end of the piezoelectric bimorph is against the dovetail groove on the corresponding driving foot, and the other end is against the dovetail groove on the corresponding fixing seat; the six piezoelectric bimorphs are simultaneously protruded inward or outward;

[0044] The six piezoelectric bimorphs are coplanar, and the plane where they are located is perpendicular to the rotation axis of the rotor;

[0045] The piezoelectric ceramic sheets on both sides of the six piezoelectric bimorphs are polarized along their thickness directions, with the polarization directions facing inward or outward at the same time.

[0046] The three driving feet are all made of flexible materials; the outer sides of the three driving feet are all provided with friction layers made of ceramic materials to improve friction performance and wear resistance.

[0047] The present invention also discloses a working method of the hollow rotating piezoelectric motor based on six-phase drive, which is as follows:

[0048] A) If the rotor needs to be driven in forward direction:

[0049] like Figure 4 As shown, the voltage signal waves u1, u2, u3, u4, u5, and u6 with the same signal amplitude and frequency but different phases are input to the 1st to 6th piezoelectric bimorphs. The formula is expressed as follows:

[0050] u i =V i f i

[0051] The phases of the electrical signals of u1, u2, u3, u4, u5, and u6 differ by 60°, respectively, and are expressed as:

[0052]

[0053]

[0054]

[0055]

[0056]

[0057]

[0058] Applying a positive voltage to the piezoelectric bimorph can cause the piezoelectric bimorph to generate bending vibration, which causes the two ends of the piezoelectric bimorph to generate a longitudinal tensile force of a certain frequency. Figure 6 As shown, the phase difference between the voltage signal waves u1 and u2 of the piezoelectric bimorph at the left and right ends of the driving foot is The two ends of the piezoelectric bimorph generate longitudinal tensile forces with different time phase differences, causing the driving foot to produce positive elliptical motion. The elliptical motion causes the contact state between the driving surface of the driving foot and the rotor to be divided into four states according to the time sequence: disengagement, pre-contact, full contact, and pre-disengagement.

[0059] The driving surface of the driving foot forms an elliptical motion with a circumference of x1. According to the friction coefficient of the contact surface and the size of the elliptical motion trajectory, the efficiency of driving the rotor's rotation is μ1. Each step of the elliptical motion is transmitted to the rotor friction surface with an effective step length of μ1x1, driving the rotor to rotate forward around the axis. After waiting for the preset time t1 seconds, the driving foot performs λ1 elliptical motions, and the effective step length of the rotor's forward rotation is λ1μ1x1.

[0060] The running trajectories and driving directions of the driving surfaces of the three driving feet are completely consistent, with only a phase difference in time. Under the coordinated action of the three driving feet, the rotor obtains continuous positive direction output torque.

[0061] B) If the rotor needs to be driven in the reverse direction:

[0062] like Figure 5 As shown, the voltage signal waves u1, u2, u3, u4, u5, and u6 with the same signal amplitude and frequency but different phases are input to the 1st to 6th piezoelectric bimorphs. The formula is expressed as follows:

[0063] u i =V i f i

[0064] The electrical signals of u6, u5, u4, u3, u2, and u1 differ by 60°, respectively, and are expressed as:

[0065]

[0066]

[0067]

[0068]

[0069]

[0070]

[0071] Applying a positive voltage to the piezoelectric bimorph can cause the piezoelectric bimorph to generate bending vibration, which causes the two ends of the piezoelectric bimorph to generate a longitudinal tensile force of a certain frequency. Figure 7 As shown, the phase difference between the voltage signal waves u1 and u2 of the piezoelectric bimorph at the left and right ends of the driving foot is The two ends of the piezoelectric bimorph generate longitudinal tensile forces with different time phase differences, causing the driving foot to produce reverse elliptical motion. The elliptical motion causes the contact state between the driving surface of the driving foot and the rotor to be divided into four states according to the time sequence: disengagement, pre-contact, full contact, and pre-disengagement.

[0072] The driving surface of the driving foot forms an elliptical motion with a circumference of x2. According to the friction coefficient of the contact surface and the size of the elliptical motion trajectory, the efficiency of driving the rotor's rotation is μ2. Each step of the elliptical motion is transmitted to the rotor friction surface with an effective step length of μ2x2, driving the rotor to rotate in the opposite direction around the axis. After waiting for the preset time t2 seconds, the driving foot performs λ2 elliptical motions, and the effective step length of the rotor's reverse rotation is λ2μ2x2.

[0073] The driving surfaces of the three driving feet have the same running trajectory and driving direction, with only a phase difference in time. Under the coordinated action of the three driving feet, the rotor obtains continuous reverse direction output torque.

[0074] By adjusting the voltage amplitude and frequency, the step length of each drive foot's elliptical motion and the time required to complete an elliptical motion can be changed, thereby varying the rotor's rotational speed. The voltage amplitude is adjusted within the permissible range without cracking the piezoelectric bimorph used; in experimental examples, the voltage amplitude is 0 to 500 Vpp. The voltage frequency can be adjusted from low to high frequencies; in experimental examples, the voltage frequency is 0 to 20 kHz, allowing the motor to operate in both non-resonant and resonant modes, achieving macro-micro fusion drive.

[0075] It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those skilled in the art in the art to which the present invention belongs. It should also be understood that terms such as those defined in common dictionaries should be understood to have meanings consistent with their meanings in the context of the prior art and, unless defined as such, will not be interpreted in an idealized or overly formal sense.

[0076] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A hollow rotating piezoelectric motor based on six-phase drive, characterized in that: It includes a rotor, a first bearing, a second bearing, a housing, a base, a stator and a piezoelectric drive module; The rotor is a hollow cylinder with two ends open. The first bearing is a deep groove ball bearing and the second bearing is a thrust bearing. The housing is fixed to the base; the outer ring of the first bearing is fixedly connected to the housing, and the inner ring is coaxially fixedly connected to the outer wall of the rotor; the lower ring of the second bearing is fixedly connected to the base, and the upper ring is coaxially fixedly connected to the lower end of the bearing, so that the rotor can rotate freely relative to the base; The stator comprises a fixing ring, three fixing seats, three connecting rods and three driving feet; The fixing ring is a hollow cylinder with two ends open; the three fixing seats are evenly arranged on the outer wall of the fixing ring and are fixedly connected to the base, so that the fixing ring is located inside the rotor and is coaxial with the rotor; The three connecting rods are evenly arranged circumferentially between the fixing ring and the rotor, with one end of each being fixedly connected to the outer wall of the fixing ring and the other end being fixedly connected to the three driving feet in a one-to-one correspondence; the three driving feet are all in contact with the inner wall of the rotor; the three fixing seats and the three connecting rods divide the fixing ring into six equal parts, and the first fixing seat is located between the first connecting rod and the second connecting rod; Both sides of the three fixing seats and the three driving feet are provided with dovetail grooves; The piezoelectric driving module includes six piezoelectric bimorphs, which are respectively arranged between the first driving foot and the first fixing seat, the first fixing seat and the second driving foot, the second driving foot and the second fixing seat, the second fixing seat and the third driving foot, the third driving foot and the third fixing seat, and the third fixing seat and the first driving foot; one end of the piezoelectric bimorph is against the dovetail groove on the corresponding driving foot, and the other end is against the dovetail groove on the corresponding fixing seat; the six piezoelectric bimorphs are simultaneously protruded inward or outward; The six piezoelectric bimorphs are coplanar, and the plane where they are located is perpendicular to the rotation axis of the rotor; The piezoelectric ceramic sheets on both sides of the six piezoelectric bimorphs are polarized along their thickness directions, with the polarization directions facing inward or outward at the same time.

2. The hollow rotating piezoelectric motor based on six-phase drive according to claim 1, characterized in that: The three driving feet are all made of flexible materials.

3. The hollow rotating piezoelectric motor based on six-phase drive according to claim 1, characterized in that: The outer sides of the three driving feet are all provided with friction layers made of ceramic material to improve friction performance and wear resistance.

4. The operating method of the hollow rotating piezoelectric motor based on six-phase drive according to claim 1, characterized in that: The following steps are involved: A) If the rotor needs to be driven in the forward direction: Voltage signal waves u1, u2, u3, u4, u5, and u6 with the same signal amplitude and frequency but different phases are input to the first to sixth piezoelectric bimorphs. The phases of the electrical signals u1, u2, u3, u4, u5, and u6 differ by 60 degrees in sequence. The two ends of the six piezoelectric bimorphs generate longitudinal tensile forces with different time phase differences, causing the three driving feet to produce positive elliptical motion. The running trajectories and driving directions of the driving surfaces of the three driving feet are completely consistent, with only a time phase difference. Under the coordinated action of the three driving feet, the rotor obtains continuous positive output torque. B) If the rotor needs to be driven in the reverse direction: Voltage signal waves u1, u2, u3, u4, u5, and u6 with the same signal amplitude and frequency but different phases are input to the first to sixth piezoelectric bimorphs. The electrical signals of u6, u5, u4, u3, u2, and u1 differ by 60° respectively. Longitudinal tensile forces with different time phase differences are generated at both ends of the six piezoelectric bimorphs, causing the three driving feet to produce opposite elliptical motions. The running trajectories and driving directions of the driving surfaces of the three driving feet are completely consistent, with only a time phase difference. Under the coordinated action of the three driving feet, the rotor obtains continuous output torque in the reverse direction.

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