A patch piezoelectric driving device for an electro-hydraulic servo valve and a working method thereof

Abstract

The application discloses a patch type piezoelectric driving device for an electro-hydraulic servo valve and a working method thereof, and the device comprises a piezoelectric driving assembly, a nozzle assembly and a base. The piezoelectric driving assembly is composed of a driving round rod, a driving disc, four groups of piezoelectric ceramic sheets and a sealing ring, and the four groups of piezoelectric ceramic sheets are uniformly distributed on the driving disc; the nozzle assembly comprises a nozzle and a sealing ring, and the nozzle is through-penetrated and communicated with a hole channel of the base. The driving assembly and the nozzle assembly are coaxially installed and fixed on the base. In working, a phase difference excitation signal is applied to the piezoelectric ceramic sheets, so that the end surface of the driving round rod generates a circumferential swing; by changing the excitation voltage amplitude, the effective flow area of a throttle port of the nozzle is controlled, and then the pressure difference on both sides of a valve core and the oil pressure of a working oil circuit are adjusted. The application has the advantages of fast response speed, high control precision, compact structure and the like, and is suitable for a high-precision electro-hydraulic servo control system.

Description

Technical Field

[0001] This invention relates to the fields of piezoelectric drive technology and electro-hydraulic servo systems, and particularly to a patch-type piezoelectric drive device for electro-hydraulic servo valves and its operating method. Background Technology

[0002] Electro-hydraulic servo valves are the core control components of electro-hydraulic servo systems. They are characterized by their small size, high control precision, fast response speed, and high reliability, and are widely used in aviation, aerospace, shipbuilding, precision equipment, and industrial control. The dynamic response capability and control precision of electro-hydraulic servo valves directly affect the working performance, stability, and service life of the entire servo system.

[0003] Currently, electro-hydraulic servo valves typically employ torque motors as the electro-mechanical conversion mechanism. Torque motors convert electrical control signals into angular mechanical motion, which then serves as the input signal to a hydraulic amplifier, driving the valve spool. However, torque motors are limited in frequency response and control accuracy due to factors such as electromagnetic inertia, mechanical inertia of moving parts, magnetic gap nonlinearity, and structural damping. Traditional electro-hydraulic servo valves generally have low bandwidth, making it difficult to meet the application requirements of high-frequency response, high precision, and rapid control scenarios.

[0004] Due to the electromagnetic inertia generated during the transient process of the inductive circuit, as well as the mechanical inertia caused by factors such as the mass and resistance of moving parts, the dynamic response capability of electromagnetic torque motors is limited. Their frequency response is typically no more than 100 Hz, and their response time is generally greater than 10 ms. Furthermore, the output driving force of electromagnetic torque motors is easily affected by changes in the magnetic gap position, resulting in the operating bandwidth of traditional electro-hydraulic servo valves typically being below 100 Hz, with a control accuracy of approximately 1%, making it difficult to meet the requirements of high-frequency response and high-precision electro-hydraulic servo control. In contrast, piezoelectric crystals and piezoelectric stacks offer advantages such as fast response speed, high displacement resolution, and high control accuracy. Their frequency response can exceed 50,000 Hz, and their response time is less than 0.1 ms, and they are widely used in nanoscale precision actuation. Therefore, if piezoelectric actuators are used to replace traditional torque motors as the electro-mechanical conversion mechanism of electro-hydraulic servo valves, the response speed, control accuracy, and dynamic performance of the electro-hydraulic servo valves can be effectively improved. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to address the problems of limited response speed, insufficient control accuracy, complex structure and difficulty in improving dynamic performance of electromagnetic torque motors in existing electro-hydraulic servo valves, and to provide a patch-type piezoelectric drive device for electro-hydraulic servo valves and its working method.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0007] A patch-type piezoelectric actuator for an electro-hydraulic servo valve comprises a stator assembly, a nozzle assembly, and a base. The nozzle assembly is symmetrically mounted on the base, and the stator assembly is coaxially mounted with the nozzle assembly. The pressure difference across the valve core is adjusted by changing the effective flow area of ​​the throttling orifice at the nozzle.

[0008] The stator assembly includes a stator disk, a stator rod, four sets of piezoelectric ceramic plates, and a sealing ring. The stator rod is coaxially arranged with the stator disk, and the four sets of piezoelectric ceramic plates are attached to the upper surface of the stator disk and evenly distributed along the circumference of the stator disk. The four sets of piezoelectric ceramic plates are symmetrically arranged, with the same included angle between adjacent sets of piezoelectric ceramic plates, and are used to excite the stator disk to generate working vibration under the action of an applied AC signal.

[0009] The nozzle assembly includes a nozzle and a sealing ring. The nozzle has a through-hole, forming an internal channel for the flow of working oil. A through-hole is provided between the sealing rings, communicating with the internal channel to form a flow path for the working oil. The nozzle end face is positioned opposite the stator rod end face, forming an adjustable flow orifice between them. The diameter of the stator rod end face matches the opening diameter of the nozzle end face, allowing the stator rod end face to engage with the nozzle opening to form a throttling structure. Each stator disc is bolted to the base, and a sealing ring inside the stator disc engages with the outer ring of the nozzle end face to achieve a seal between the stator disc and the nozzle end face.

[0010] The working method of the patch-type piezoelectric drive device of the present invention is as follows: AC excitation signals with phase differences of one-quarter of a cycle are applied to four sets of piezoelectric ceramic plates, causing the stator disk to generate circumferential bending working mode vibration, which in turn drives the stator rod to generate bending vibration in two mutually orthogonal transverse directions. The two orthogonal bending vibrations are one-quarter of a cycle apart in time, and their superposition causes the end of the stator rod to rotate and oscillate around its axis. By changing the excitation voltage amplitude, the offset of the stator rod end relative to the nozzle center can be changed, thereby changing the coverage area of ​​the stator rod end face to the nozzle, realizing the adjustment of the effective flow area of ​​the adjustable orifice, and thus changing the pressure difference across the servo valve core and the oil pressure in the working oil circuit.

[0011] Compared with the prior art, the present invention has the following beneficial effects:

[0012] This invention employs a patch-type piezoelectric drive device to replace the traditional torque motor. By adjusting the effective flow area of ​​the adjustable orifice at the nozzle, the pressure difference across the servo valve core is controlled. This piezoelectric drive structure has advantages such as simple and compact structure, short transmission chain, fast response speed, and high control precision, which helps to reduce the size and weight of the electro-hydraulic servo valve and improve the dynamic response capability and operational reliability of the system. Simultaneously, the device can continuously adjust the orifice area by adjusting the excitation voltage amplitude, providing flexible control and making it suitable for high-frequency response, high-precision electro-hydraulic servo control systems. Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 is a schematic diagram of the overall structure of the patch piezoelectric drive device.

[0015] Figure 2 is a cross-sectional view of the nozzle assembly and the stator assembly.

[0016] Figure 3 is a structural diagram of the nozzle assembly.

[0017] Figure 4 is a front view of the stator assembly.

[0018] Figure 5 is the main view of the stator assembly.

[0019] Figure 6 is a front view of the stator assembly.

[0020] Figure 7 is a front view of the nozzle assembly.

[0021] Figure 8 is a cross-sectional view of the nozzle assembly.

[0022] Figure 9 shows the curves of the electrical signals applied to the four sets of piezoelectric ceramic sheets over time.

[0023] Figure 10 is a schematic diagram of the four working modes.

[0024] Figure 11 shows the array configuration of the stator rods under different voltage amplitudes.

[0025] Figure 12 shows the location of the patch piezoelectric actuator in the entire electro-hydraulic servo valve.

[0026] Among them: 1. Stator assembly, 1.1. Stator disc, 1.2. Stator rod, 1.3. Piezoelectric ceramic sheet, 1.4. Sealing ring, 2. Nozzle assembly, 2.1. Nozzle, 2.2. Sealing ring, 3. Base. Detailed Implementation

[0027] The present invention will now be described in further detail with reference to the accompanying drawings.

[0028] As shown in Figure 1, the patch-type piezoelectric drive device of the present invention consists of a stator assembly (1), a nozzle assembly (2), and a base (3). The nozzle assembly (2) is installed inside the base (3), and the stator assembly (1) is installed on the base (3) and is coaxially opposite to the nozzle assembly (2) for adjusting the pressure difference on both sides of the valve core by changing the effective flow area at the nozzle orifice.

[0029] Figure 2 shows an assembly cross-sectional view along the plane containing the axes of the stator assembly (1) and the nozzle assembly (2). The stator assembly (1) and the nozzle assembly (2) are coaxially mounted, and their assembly relationship is shown in Figure 3. Figure 4 shows an installation cross-sectional view of the stator assembly (1) and the nozzle assembly (2). A sealing ring (1.4) is provided on the inner side of the stator disk (1.1). The sealing ring (1.4) cooperates with the outer ring of the nozzle (2.1) end to achieve a seal between the nozzle assembly (2) and the stator assembly (1). At the same time, the arrangement of the sealing ring (1.4) avoids the main working area of ​​the piezoelectric ceramic sheet (1.3) to reduce the influence of the sealing structure on the vibration of the stator disk (1.1) driven by the piezoelectric ceramic sheet (1.3). Figure 5 shows the structural form of the stator assembly (1). Four sets of piezoelectric ceramic sheets (1.3) are evenly distributed on the upper surface of the stator disk (1.1). The stator disk (1.1) is fixed to the base (3) by four bolts. Figure 6 is a front view of the stator assembly (1).

[0030] As shown in Figures 7 and 8, the nozzle assembly (2) includes a nozzle (2.1) and a sealing ring (2.2). The nozzle (2.1) has an axial through-hole, forming an axial flow channel for the working oil. The outer surface of the nozzle (2.1) is provided with a sealing ring (2.2), and a radial through-hole communicating with the internal flow channel of the nozzle (2.1) is provided between adjacent sealing rings (2.2). Through this structure, the nozzle assembly (2) can cooperate with the channel in the base (3) to form a flow path for the working oil.

[0031] This invention excites the stator assembly (1) to generate compound bending vibration by applying electrical signals with phase differences to different piezoelectric ceramic sheets (1.3), causing the end of the stator rod (1.2) to oscillate around its axis. As shown in Figure 9, the four sets of piezoelectric ceramic sheets (1.3) are sequentially labeled P1, P2, P3, and P4 along the circumference of the stator disk (1.1). Excitation electrical signals of cos(ωt), sin(ωt), -cos(ωt), and -sin(ωt) are applied to P1, P2, P3, and P4, respectively, where the positive direction of the voltage is defined as the direction from the center of the stator disk (1.1) to the end of the stator rod (1.2). Under the above four-phase orthogonal excitation, the stator disk (1.1) generates circumferential bending vibration and transmits this vibration to the stator rod (1.2). The stator rod (1.2) generates bending vibrations in two mutually orthogonal transverse directions, and the two transverse bending vibrations are separated by a quarter of a period in time. After the two orthogonal bending vibrations are superimposed, the end of the stator rod (1.2) rotates and oscillates continuously with its axis as the center.

[0032] Figure 10 (a)- Figure 10 (d) shows the bending vibration state of the stator rod (1.2) at different times within one excitation cycle. Let the excitation period be T, and T = 2π / ω, where n is an integer.

[0033] like Figure 10 As shown in (a), when t=nT, the voltages of piezoelectric ceramic plates P1 and P3 are at the peak and trough respectively, while the voltages of piezoelectric ceramic plates P2 and P4 are both 0. At this time, the stator rod (1.2) bends and vibrates in the direction from P1 to P3.

[0034] like Figure 10 As shown in (b), when t=nT+T / 4, the voltages of piezoelectric ceramic plates P2 and P4 are at the peak and trough respectively, while the voltages of piezoelectric ceramic plates P1 and P3 are both 0. At this time, the stator rod (1.2) undergoes bending vibration along the direction from P2 to P4.

[0035] like Figure 10 As shown in (c), when t=nT+T / 2, the voltages of piezoelectric ceramic plates P3 and P1 are at the peak and trough respectively, while the voltages of piezoelectric ceramic plates P2 and P4 are both 0. At this time, the stator rod (1.2) bends and vibrates in the direction from P3 to P1.

[0036] like Figure 10As shown in (d), when t=nT+3T / 4, the voltages of piezoelectric ceramic plates P4 and P2 are at the peak and trough respectively, while the voltages of piezoelectric ceramic plates P1 and P3 are both 0. At this time, the stator rod (1.2) undergoes bending vibration along the direction from P4 to P2.

[0037] Therefore, throughout the entire excitation cycle, the end of the stator rod (1.2) bends sequentially along the directions P1—P3, P2—P4, P3—P1, and P4—P2, thus forming a continuous rotational oscillation around its axis. When the excitation voltage amplitude remains constant, the offset of the end of the stator rod (1.2) relative to the center of the nozzle (2.1) remains constant, and the covering area of ​​the stator rod (1.2) end face to the nozzle orifice remains constant. Therefore, the effective flow area of ​​the adjustable orifice is constant under this voltage amplitude, and the pressure difference across the valve core remains stable.

[0038] Figure 11 shows the vibration state of the stator rod (1.2) under different voltage amplitudes. As the excitation voltage amplitude increases, at the same phase moment, the offset of the end of the stator rod (1.2) relative to the center of the nozzle (2.1) increases, the coverage area of ​​the stator rod (1.2) end face to the nozzle orifice section decreases, and the effective flow area of ​​the orifice at the nozzle (2.1) increases. Since the effective flow area of ​​the orifice in the electro-hydraulic servo valve directly affects the pressure difference on both sides of the valve core, and thus affects the oil pressure in the working oil circuit, the output oil pressure of the servo valve can be controlled by adjusting the excitation voltage amplitude.

[0039] The embodiments in this specification are described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other. For the device structure embodiments, there is a corresponding relationship with the working method embodiments; therefore, the relevant working process can be found in the description of the method embodiments. The above descriptions are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any equivalent substitutions, modifications, or improvements made by those skilled in the art within the scope of the technology disclosed in this invention, based on the technical solutions and concepts of the present invention, should be covered within the scope of protection of this invention. The scope of protection of this invention should be determined by the scope defined in the claims.

Claims

1. A patch piezoelectric drive device for an electro-hydraulic servo valve, comprising a piezoelectric drive assembly (1), a nozzle assembly (2), and a base (3); the nozzle assembly (2) is symmetrically mounted on the base (3), and the patch piezoelectric drive assembly (1) is mounted on one side of the nozzle assembly (2) and coaxially cooperates with the nozzle assembly (2) to adjust the effective throttling area at the nozzle assembly (2); Its features are, The piezoelectric drive assembly (1) includes a drive disk (1.1), a drive rod (1.2), four sets of piezoelectric ceramic sheets (1.3), and a sealing ring (1.4). The drive rod (1.2) is coaxially arranged with the drive disk (1.1), and the drive disk (1.1) is located on the upper end face of the drive rod (1.2). The four sets of piezoelectric ceramic sheets (1.3) are attached to the drive disk (1.1). The four sets of piezoelectric ceramic sheets (1.3) are evenly distributed along the circumference of the drive disk (1.1), and the included angle between two adjacent sets of piezoelectric ceramic sheets (1.3) is the same. The piezoelectric ceramic sheets are arranged in a centrally symmetrical layout so as to drive the drive disk (1.1) to generate bending vibration under the action of an applied AC signal. One end of the driving rod (1.2) is connected to the driving disk (1.1), and the other end is set toward the nozzle orifice of the nozzle assembly (2). When the four sets of piezoelectric ceramic sheets (1.3) are excited by the phase difference, the vibration of the driving disk (1.1) is transmitted to the driving rod (1.2), causing the end of the driving rod (1.2) to swing relative to the nozzle orifice of the nozzle assembly (2), thereby changing the covering area and effective flow area at the nozzle orifice. The nozzle assembly (2) includes a nozzle (2.1) and a sealing ring (2.2); the nozzle (2.1) is internally open, forming an internal channel for the flow of working oil; the nozzle (2.1) has a through hole between the sealing ring (2.2), which communicates with the internal channel of the nozzle (2.1) to form a flow path for the working oil; the end of the nozzle (2.1) is positioned opposite to the end face of the drive rod (1.2), forming an adjustable flow orifice between them; the effective flow area of ​​the adjustable flow orifice changes with the position of the end of the drive rod (1.2) relative to the end of the nozzle (2.1).

2. The patch-type piezoelectric drive device for an electro-hydraulic servo valve according to claim 1, characterized in that, The end face diameter of the driving rod (1.2) is equal to the inner diameter of the nozzle (2.1) opening, so that the end face of the driving rod (1.2) can match the nozzle (2.1) opening and form an adjustable flow hole structure.

3. The patch-type piezoelectric drive device for an electro-hydraulic servo valve according to claim 2, characterized in that, An initial gap is provided between the end face of the driving rod (1.2) and the opening of the nozzle (2.1), and the initial gap is used to form the initial flow area of ​​the adjustable flow orifice.

4. The patch-type piezoelectric drive device for an electro-hydraulic servo valve according to claim 1, characterized in that, The four sets of piezoelectric ceramic sheets (1.3) are evenly arranged at 90° intervals along the circumference of the drive disk (1.1), and the two sets of piezoelectric ceramic sheets (1.3) arranged opposite each other are symmetrical about the central axis of the drive disk (1.1).

5. The patch-type piezoelectric drive device for an electro-hydraulic servo valve according to claim 1, characterized in that, The drive discs (1.1) located on both sides are fixed to the base (3) by four bolts to ensure that the installation position between the piezoelectric drive assembly (1) and the nozzle assembly (2) is fixed.

6. The patch-type piezoelectric drive device for an electro-hydraulic servo valve according to claim 1, characterized in that, The drive disc (1.1) is provided with a sealing ring (1.4). The inner diameter of the sealing ring (1.4) matches the outer diameter of the four sets of piezoelectric ceramic sheets (1.3) and matches the outer diameter of the nozzle (2.1) end, so as to achieve a sealing fit between the drive disc (1.1) and the nozzle (2.1) end.

7. The patch-type piezoelectric drive device for an electro-hydraulic servo valve according to claim 1, characterized in that, The nozzle (2.1) is provided with a through flow channel along its axial direction, and the side wall of the nozzle (2.1) is provided with a radial through hole communicating with the through flow channel. The radial through hole is located between the two sealing rings (2.2) of the nozzle assembly (2).

8. The patch-type piezoelectric drive device for an electro-hydraulic servo valve according to claim 1, characterized in that, The base (3) has three channels below it. The channels on the left and right sides are connected to the flow area of ​​the radial through hole on the side wall of the corresponding nozzle (2.1), and the channel in the middle is connected to the flow area of ​​the nozzle orifice of the corresponding nozzle assembly (2).

9. The patch-type piezoelectric drive device for an electro-hydraulic servo valve according to claim 1, characterized in that, The base (3) has four bolt holes on its upper part, which are used to fix the base (3) to the valve body of the electro-hydraulic servo valve.

10. The patch-type piezoelectric drive device for electro-hydraulic servo valve and its working method according to claim 1, characterized in that: 1) Four sets of piezoelectric ceramic sheets (1.3) are sequentially labeled P1, P2, P3, and P4 along the circumference of the driving disk (1.1), and excitation electrical signals of cos(ωt), sin(ωt), -cos(ωt), and -sin(ωt) are applied to the piezoelectric ceramic sheets P1, P2, P3, and P4 respectively; wherein, the positive direction of the voltage is defined as the direction from the center of the driving disk (1.1) to the head of the driving rod (1.2). Under the above four-phase orthogonal excitation, the driving disk (1.1) generates circumferential bending working mode vibration, and drives the driving rod (1.2) to generate bending vibration in two mutually orthogonal transverse directions; the two transverse bending vibrations are a quarter of a period apart in time, and after superposition, they cause the end of the driving rod (1.2) to rotate and swing around its axis; 2) Let the excitation period be T, and T = 2π / ω, where n is an integer. When t = nT, the voltages of piezoelectric ceramic plates P1 and P3 are at the peak and trough respectively. At this time, the voltages of piezoelectric ceramic plates P2 and P4 are both 0, driving the circular rod (1.2) to bend and vibrate in the direction from P1 to P3. When t=nT+T / 4, the voltages of piezoelectric ceramic plates P2 and P4 are at the peak and trough respectively. At this time, the voltages of piezoelectric ceramic plates P1 and P3 are both 0, driving the round rod (1.2) to bend and vibrate in the direction from P2 to P4. When t=nT+T / 2, the voltages of piezoelectric ceramic sheet P3 and piezoelectric ceramic sheet P1 are at the peak and trough respectively. At this time, the voltages of piezoelectric ceramic sheet P2 and piezoelectric ceramic sheet P4 are both 0, driving the round rod (1.2) to bend and vibrate in the direction from P3 to P1. When t=nT+3T / 4, the voltages of piezoelectric ceramic plates P4 and P2 are at the peak and trough respectively. At this time, the voltages of piezoelectric ceramic plates P1 and P3 are both 0, driving the round rod (1.2) to bend and vibrate in the direction from P4 to P2. Thus, within a complete excitation cycle, the end of the driving rod (1.2) bends sequentially along the directions of P1-P3, P2-P4, P3-P1 and P4-P2, forming a continuous rotational oscillation around its axis; 3) When the excitation voltage amplitude remains constant, the offset of the end of the driving rod (1.2) relative to the center of the nozzle (2.1) remains constant, and the covering area of ​​the end of the driving rod (1.2) on the nozzle cross section remains constant, so that the effective flow area of ​​the adjustable flow port remains constant under this voltage amplitude, and the pressure difference on both sides of the valve core remains stable. 4) As the excitation voltage amplitude increases, at the same phase moment, the offset of the end of the driving rod (1.2) relative to the center of the nozzle (2.1) gradually increases, the covering area of ​​the end of the driving rod (1.2) on the nozzle orifice gradually decreases, and the effective flow area of ​​the adjustable flow port at the nozzle (2.1) gradually increases; by changing the excitation voltage amplitude, the effective flow area of ​​the flow port can be controlled, thereby adjusting the pressure difference on both sides of the valve core and the oil pressure of the working oil circuit.

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