阅读说明：本技术 用于飞行器飞行控制致动和燃料控制系统的压电环形弯曲体伺服阀组件 (Piezoelectric toroidal flexure servovalve assembly for aircraft flight control actuation and fuel control system ) 是由 袁忠民 于 2020-04-02 设计创作，主要内容包括：压电环形弯曲体伺服阀组件通过移除现有技术伺服阀中使用的机械部件来减少机械磨损。该组件不使用转矩电机、挡板和反馈弹簧。以这种方式,不需要移动件,这减少了维护和成本。成对的压电环形弯曲体与成对的喷嘴相邻地安装。压电环形弯曲体通过在允许流动的打开位置和限制流动的关闭位置之间移动,从而独立地调节通过喷嘴的流体流。线性位置感测设备测量阀芯位置并将关于该阀芯位置的反馈提供给阀控制器。阀控制器允许滑阀移动直到阀位置达到命令位置并且滑阀上的力与跨滑阀的压力差平衡。H桥可操作以切换施加到负载上的压力差的极性。(The piezoelectric annular flexure servovalve assembly reduces mechanical wear by removing mechanical components used in prior art servovalves. The assembly does not use a torque motor, a damper and a feedback spring. In this way, no moving parts are required, which reduces maintenance and costs. Pairs of piezoelectric toroidal flexures are mounted adjacent to pairs of nozzles. The piezoelectric annular flexures independently regulate fluid flow through the nozzles by moving between an open position that permits flow and a closed position that restricts flow. The linear position sensing device measures the spool position and provides feedback to the valve controller regarding the spool position. The valve controller allows the spool valve to move until the valve position reaches the commanded position and the force on the spool valve balances the pressure differential across the spool valve. The H-bridge is operable to switch the polarity of the pressure differential applied to the load.)

1. A piezoelectric ring flexure servovalve assembly, said assembly comprising:

a valve housing defined by a passage operable to convey a fluid;

a pair of nozzles in fluid communication with the fluid, the nozzles terminating at a pair of orifices;

a pair of piezoelectric flexible members disposed adjacent a nozzle, the piezoelectric flexible members operable to flex to an open position away from the nozzle to enable the fluid to flow through the nozzle, the piezoelectric flexible members operable to return to a closed position toward the nozzle to at least partially restrict flow through the nozzle;

a spool valve operably connected to the piezoelectric bendable member, the spool valve being disposed in at least one spool position to regulate fluid flow through the passage, the piezoelectric bendable member controlling operation of the spool position;

a variable restrictor operably connected to the nozzle, the variable restrictor generating a pressure differential across the spool when the two curtain areas between the piezoelectric bendable member and the nozzle are not equal;

a linear position sensing device operatively connected to the spool valve, a linear positioning device determining a spool position of the spool valve, the linear positioning device providing feedback regarding the spool position;

a valve controller operatively connected to the linear position sensing device and the spool valve, the valve controller receiving feedback from the linear position sensing device, whereby based on the feedback, the valve controller transmits an electrical command signal commanding the spool valve to move until the spool position reaches a commanded position and a force on the spool valve balances a pressure differential across the spool valve; and

a piezoelectric driver generating a voltage proportional to the electrical command signal from the valve controller to control bending of the piezoelectric bendable member.

2. The assembly of claim 1, wherein the piezoelectric bendable members bend independently of each other to independently regulate flow through the nozzle.

3. The assembly of claim 1, wherein the variable flow restrictor is controlled by valve control software.

4. The assembly of claim 1, further comprising an H-bridge operable to switch the polarity of the pressure differential applied to the load.

5. The assembly of claim 4, wherein the H-bridge comprises four switches.

6. The assembly of claim 1, wherein the piezoelectric bendable member is non-metallic.

7. The assembly of claim 1, wherein the piezoelectric bendable member comprises a piezoelectric annular flexure.

8. The assembly of claim 7, wherein the piezoelectric bendable member comprises at least two piezoelectric annular flexures.

9. An assembly according to claim 1 wherein the piezoelectric bendable member comprises a single layer made of a layer of piezoelectric ceramic material pressed at a compression force of up to 1 MN.

10. The assembly of claim 1, wherein the piezoelectric bendable member comprises a plurality of layers made by casting very thin layers of piezoelectric ceramic material with thin layers of electrode material deposited thereon.

11. The assembly of claim 1, further comprising a piezoelectric driver.

12. The assembly of claim 11, wherein the piezoelectric driver generates an output voltage proportional to the electrical command signal to actuate the piezoelectric bendable member.

13. The assembly of claim 1, wherein the valve controller generates an electrical signal.

14. The assembly of claim 13 wherein the electrical signal generated by the valve controller commands the piezoelectric driver to actuate the piezoelectric bendable member to bend.

15. The assembly of claim 1, further comprising a control loop.

16. The assembly of claim 15, wherein the spool position is in a closed position control loop.

17. The assembly of claim 16 wherein the closed spool position control loop enables parameter degradation within the loop to be compensated for by the control loop.

Technical Field

The present invention relates generally to a piezoelectric toroidal flexure servovalve assembly for aircraft flight control actuation and fuel control systems. More importantly, the piezoelectric servo valve reduces mechanical wear by removing the prior art torque motor, flapper and feedback spring and replacing them with pairs of piezoelectric flexible members, so that the piezoelectric servo valve is substantially free of moving parts; wherein the assembly: replacing the electromagnetic torque motor and the resulting transducer effect with a pair of piezoelectric bendable members mounted directly adjacent to the pair of nozzles; independently regulating fluid flow through the nozzles; replacing the baffle with a piezoelectric bendable member; replacing a feedback spring that regulates the spool valve with a linear position sensing device that measures spool position and provides feedback to the valve controller regarding spool position, and a valve controller that allows the spool valve to move until the valve position reaches a commanded position and the force on the spool valve balances the pressure differential across the spool valve; and forming an H-bridge in which pairs of nozzles are variable flow restrictors controlled by valve control software, creating a pressure differential across the spool valve as the piezoelectric bendable member bends away from the nozzles.

Background

The following background information may present examples of certain aspects of the prior art (e.g., without limitation, methods, facts, or common sense) which, while intended to be helpful in further teaching the reader of additional aspects related to the prior art, should not be construed as limiting the invention or any embodiment thereof to any matter described or suggested therein or inferred therefrom.

Those skilled in the art will recognize that two-stage electro-hydraulic servo valves with mechanical feedback are widely used in aircraft flight control actuation and control of fuel control systems, and a lightweight and compact servo control valve almost anywhere would prove advantageous. It is also known that prior art servo valves utilize an electromagnetic torque motor supported on a flexible tube that provides a frictionless pivot and isolates the torque motor from the hydraulic fluid. The torque motor acts as an electrical to mechanical transducer and converts electrical signals to mechanical torque.

Prior art servo valves also utilize baffles driven by torque motors to differentially restrict flow from the paired nozzles. Further, prior art servo valves have a first stage hydraulic circuit forming an H-bridge, where the paired nozzles are variable restrictors that create a pressure differential across the spool valve when the flapper is off-center. The feedback spring allows the spool to move until the restoring force on the flapper balances the electromagnetic torque, whereupon the flapper is re-centered. The present invention reduces mechanical wear by removing the main mechanical parts from known prior art servo valves.

In general, the piezoelectric effect is the ability of certain materials to generate an electrical charge in response to an applied mechanical stress. The piezoelectric properties of quartz can be used as a frequency standard. Quartz clocks employ a crystal oscillator made of a quartz crystal that uses a combination of both positive and negative voltage to generate a series of regularly timed electrical pulses that are used to mark time.

Other proposals relate to valves for aircraft flight control actuation and fuel control systems. A problem with these systems is that they can cause significant wear in metal mechanical parts such as valves, springs and shutters. While the clamping devices cited above satisfy some of the needs of the marketplace, there remains a need for a piezoelectric toroidal flexure servovalve assembly for aircraft flight control actuation and fuel control systems.

Disclosure of Invention

Illustrative embodiments of the present disclosure generally relate to a piezoelectric toroidal flexure servovalve assembly for aircraft flight control actuation and fuel control systems. A piezoelectric annular flexure servovalve assembly is used to replace the prior art electromagnetic torque motor and the resulting transducer effect with a pair of piezoelectric flexure members mounted directly adjacent to a pair of nozzles.

The piezoelectric bendable member selectively allows and restricts flow through the nozzle. The piezoelectric bendable members are configured to independently regulate fluid flow through the nozzles. The piezoelectric bendable member also replaces the flapper found in prior art servo valves by performing substantially the same function.

In some embodiments, the assembly replaces the feedback spring that regulates the spool valve with a linear position sensing device. The linear position sensing device is configured to measure the spool position and provide feedback to the valve controller regarding the spool position. In addition, the assembly provides a valve controller that allows the spool valve to move until the valve position reaches the commanded position and the force on the spool valve balances the pressure differential across the spool valve.

The assembly is also configured with a different H-bridge than taught in the prior art. The disclosed H-bridge is operable such that the paired nozzles act as variable flow restrictors and are controlled by valve control software. When the piezoelectric bending element bends away from the nozzle, it creates a pressure differential across the spool valve.

In one possible embodiment, the piezoelectric ring flexure servovalve assembly provides various piezoelectric-based components that reduce the need for metallic, wear components from the prior art. The assembly may include a valve housing defined by a passage operable to convey a fluid.

The assembly also provides a pair of nozzles in fluid communication, the nozzles terminating at a pair of orifices.

The assembly also provides a pair of piezoelectric annular flexures disposed adjacent the nozzle, the piezoelectric annular flexures being operable to flex independently of one another to an open position away from the nozzle to enable fluid flow through the nozzle, the piezoelectric annular flexures being operable to return to a closed position toward the nozzle to at least partially restrict flow through the nozzle.

Further, the assembly may include a piezoelectric driver operable to actuate the piezoelectric toroidal flexure.

The assembly also provides a spool valve operatively connected to the piezoelectric toroidal flexure, the spool valve disposed at least one spool position to regulate fluid flow through the passage, the piezoelectric toroidal flexure controlling operation of the spool position.

The assembly may further comprise a variable flow restrictor operatively connected to the nozzle, the variable flow restrictor generating a pressure differential across the spool when the piezoelectric toroidal flexure is in the open position, the variable flow restrictor being controlled by the valve control software.

The assembly also provides a linear position sensing device operatively connected to the spool valve, the linear positioning device determining a spool position of the spool valve, the linear positioning device providing feedback regarding the spool position.

Further, the assembly may include a valve controller operatively connected to the linear position sensing device and the spool valve, the valve controller receiving feedback from the linear position sensing device, based on which the valve controller allows the spool valve to move until the spool position reaches the commanded position and the force on the spool valve balances the pressure differential across the spool valve.

The assembly also provides an H-bridge operable to switch the polarity of the pressure differential applied to the load, the H-bridge comprising four switches.

In another aspect, the piezoelectric bendable member is controlled to bend by an electrical signal generated by a valve controller operatively connected to the piezoelectric driver.

In another aspect, the piezoelectric bendable member is non-metallic.

In another aspect, the piezoelectric bendable member comprises a piezoelectric annular bender.

In another aspect, the piezoelectric bendable member comprises a single layer made of a layer of piezoelectric ceramic material pressed at a compaction force of up to 1MN, or a plurality of layers made by casting very thin layers of piezoelectric ceramic material on which thin layers of electrode material are deposited.

In another aspect, the piezoelectric driver actuates the piezoelectric bendable member.

In another aspect, the circuit is closed at the spool position such that parameter degradation within the circuit is compensated for by the control circuit.

It is an object of the present invention to minimize mechanical wear on the servo valve.

Another object is to provide a piezoelectric servo valve that does not use a torque motor, flapper, or feedback spring to reduce mechanical wear.

Another object is to provide pairs of piezoelectric bendable members located directly in front of and restricting flow through the servo valve nozzle.

Another object is to provide a highly reliable servo valve which is substantially free of mechanical failure. This is achieved by: the torque motor, flapper, and feedback spring are removed and the piezoelectric bendable member is used to make the servo valve first stage free of movement.

Another object is to provide a servo valve that is highly reliable and less prone to contamination of the fluid. This is achieved by: each nozzle is independently restricted so that the maximum cutting shear force of the slide valve can be obtained at any time and at any position.

Another object is to provide a highly reliable servo valve that is less prone to nozzle clogging. This is achieved by: each nozzle is independently restricted so that the nozzle size can be independently selected to meet maximum contaminant particle size requirements to prevent the nozzles from becoming clogged with contaminant particles.

Another object is to provide a low power loss servo valve to minimize the continuous flow losses through the nozzle. This is achieved by: each nozzle is independently restricted so that one of the nozzles is always closed at any given time, and both nozzles are closed or mostly closed when the valve is in the armed state. The amount of static flow through the nozzle is equal to the flow required to hold the slide valve in place.

Another object is to provide a servo valve with a very high bandwidth. This is achieved by: each nozzle is independently restricted so that the size of the fixed orifice can be determined based on the servo valve bandwidth requirements.

Another object is to provide a servo valve without zero offset and displacement. This is achieved by: the circuit is closed in the spool position so that parameter degradation in the circuit will be compensated by the control circuit.

Another object is to provide a servo valve which is relatively simple and compact in construction, easy to manufacture and which does not require adjustment. This is achieved by: the torque motor, flapper and feedback spring are removed and the piezoelectric flexure is used so that the servo valve structure becomes simpler and more compact, easier to manufacture and requires no adjustment.

It is another object to provide a servo valve that can operate and survive in high gravity and high vibration environments. This is achieved by: the torque motor, flapper, and feedback spring are removed and the piezoelectric bendable member is used to make the servo valve first stage free of movement.

Other systems, devices, methods, features and advantages will be, or will become, apparent to one with skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features and advantages be included within this description, be within the scope of the present disclosure, and be protected by the accompanying claims and drawings.

Drawings

The invention will now be described, by way of example, with reference to the accompanying drawings, in which:

FIG. 1 illustrates a schematic diagram of an exemplary piezoelectric annular flexure servovalve assembly for an aircraft flight control actuation and fuel control system showing paired piezoelectric flexures in a closed position in accordance with an embodiment of the present invention;

FIG. 2 illustrates a pair of exemplary piezoelectric bendable members according to an embodiment of the invention;

FIG. 3 illustrates a schematic diagram of a piezoelectric ring flexure servovalve assembly showing a first piezoelectric flexure member in a closed position and a second piezoelectric flexure member in an open position in accordance with an embodiment of the present invention;

FIG. 4 illustrates a schematic diagram of a piezoelectric ring flexure servovalve assembly showing a first piezoelectric flexure member in an open position and a second piezoelectric flexure member in a closed position in accordance with an embodiment of the present invention;

FIG. 5 illustrates a schematic diagram of a piezoelectric ring flexure servovalve assembly showing two piezoelectric flexure members both in an open position, in accordance with an embodiment of the present invention;

FIG. 6 shows a schematic view of a piezoelectric bendable member in a closed position according to an embodiment of the invention; and

FIG. 7 illustrates a schematic view of an exemplary spool valve according to an embodiment of the present invention.

Like reference numerals refer to like parts throughout the various views of the drawings.

Detailed Description

The following detailed description is merely exemplary in nature and is not intended to limit the described embodiments or the application and uses of the described embodiments. As used herein, the word "exemplary" or "illustrative" means "serving as an example, instance, or illustration. Any implementation described herein as "exemplary" or "illustrative" is not necessarily to be construed as preferred or advantageous over other implementations. All of the implementations described below are exemplary implementations provided to enable persons skilled in the art to make or use the embodiments of the present disclosure and are not intended to limit the scope of the present disclosure, which is defined by the claims. For purposes of the description herein, the terms "upper," "lower," "left," "rear," "right," "front," "vertical," "horizontal," and derivatives thereof shall relate to the invention as oriented in fig. 1. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary or the following detailed description. It is also to be understood that the specific devices and processes illustrated in the attached drawings, and described in the following specification are simply exemplary embodiments of the inventive concepts defined in the appended claims. Hence, specific dimensions and other physical characteristics relating to the embodiments disclosed herein are not to be considered as limiting, unless the claims expressly state otherwise.

FIG. 1 refers to a piezoelectric toroidal flexure servovalve assembly 100 for an aircraft flight control actuation and fuel control system. Piezoelectric annular flexure servovalve assembly 100, hereinafter "assembly 100," includes a valve housing 102 that provides a protective housing for the components of assembly 100. The housing 102 forms a structural framework for the servo valve. Suitable materials for the housing 102 may include, but are not limited to, steel, iron, metal alloys, and titanium.

As shown in FIG. 3, valve housing 102 forms a passage 104 for conveying a fluid. The fluid may include, but is not limited to, jet fuel, hydraulic oil, engine oil, and other aviation-related fluids known in the art. In some embodiments, pairs of nozzles 106a-b operate within valve housing 102. The nozzles 106a, 106b are in fluid communication with a fluid. The nozzles 106a-b deliver fluid to the appropriate outlet ports in a controlled manner.

In some embodiments, nozzles 106a-b terminate at pairs of orifices 108a-b that vent fluid out of valve housing 102 through passage 104 to hydrodynamic return port Pr. The nozzles 106a-b may have a circular shape with a profiled channel or may be protruding to produce a steady and strong flow velocity.

In some embodiments, the pair of ports 108a-b are connected to the same hydrodynamic supply inlet port Ps. The orifice may have a circular shape or may protrude to produce a stronger flow rate.

Turning now to FIG. 2, the assembly 100 provides pairs of piezoelectric bendable members 110a-b that exhibit a piezoelectric effect. One skilled in the art will recognize that the piezoelectric effect is the ability of certain materials to generate an electrical charge in response to an applied mechanical stress (a substance being squeezed or stretched). Conversely, mechanical deformation (contraction or expansion of a substance) occurs when an electric field is applied. The piezoelectric bendable members 110a-b are alternatives for the torque motors and baffles commonly used in the art. In essence, the bendable members 110a-b act as electrical to mechanical transducers, converting electrical signals into mechanical forces and displacements. It is noted, however, that the bendable members 110a-b perform a similar function of regulating flow through the nozzles 106 a-b.

The piezoelectric bendable members 110a-b are operable to bend to enable fluid flow through the nozzles 106 a-b. In one embodiment, the piezoelectric driver 122 actuates the piezoelectric bendable members 110a-b to bend in response to an electrical signal. The driver 122 is in operable contact with the valve controller 116. The piezoelectric bendable members 110a-b bend independently of each other. Thus, the piezoelectric bendable members 110a-b are configured to independently regulate fluid flow through the nozzles 106 a-b.

Referring to FIG. 6, the piezoelectric bendable members 110a-b are disposed adjacent to the nozzles 106a-b such that the piezoelectric bendable members 110a-b move between an open position 124 and a closed position 126 to regulate fluid flow through the nozzles 106 a-b. Thus, the piezoelectric bendable members 110a-b prevent fluid flow through the nozzles 106a-b (FIG. 3) due to the closed position 126. And the piezoelectric bendable members 110a-b enable controlled fluid flow through the nozzles 106a-b (fig. 5) due to the open, bent position 124.

In addition, the piezoelectric bendable members 110a-b move between the open position 124 and the closed position 126 independently of one another. Thus, as shown in fig. 3, the first piezoelectric bendable member 110a may be in the closed position 126 to restrict flow through the nozzle; while the second piezoelectric bendable member 110b may be in the open position 124 to allow flow through the nozzle.

Conversely, fig. 4 shows how the first piezoelectric bendable member 110a may be in the open position 124 to enable flow through the nozzle; and the second piezoelectric bendable member 110b may be in the closed position 124 to restrict flow through the nozzle. Thus, as shown in fig. 1-4, there are four position combinations for the two piezoelectric bendable members 110a, 110 b.

In one non-limiting embodiment, the piezoelectric bendable member 110a-b includes two piezoelectric annular flexures. In another possible embodiment, the piezoelectric bendable members 110a-b comprise a single layer made of a layer of piezoelectric ceramic material pressed at a pressing force of up to 1 MN. The piezoelectric flexures 110a-b may also be made of multiple layers fabricated by tape casting very thin layers of piezoelectric ceramic material on which thin layers of electrode material are deposited. Other piezoelectric materials and build compositions may also be used.

Looking again at fig. 1, the assembly 100 includes a spool valve 112. The spool valve 112 is disposed in at least one spool position to regulate fluid flow through the passage 104. In one embodiment, spool valve 112 is essentially a directional control valve. Spool valve 112 allows fluid to flow from one or more sources into different paths. Spool valve 112 includes a spool that is mechanically or electrically controlled within a post.

Thus, the assembly 100 does not rely on a feedback spring to control the spool valve 112. Rather, the assembly 100 utilizes a linear position sensing device 114 operatively connected to the spool valve 112. The linear position sensing device 114 is configured to measure the spool position and provide feedback regarding the spool position. In this manner, the spool position dictates the operation of the piezoelectric bendable members 110 a-b.

Further, a valve controller 116 is operatively connected to the linear position sensing device 114. The valve controller 116 receives feedback from the linear position sensing device 114 and processes it accordingly. The valve controller 116 allows the spool valve 112 to move until the spool position reaches the commanded position and the force on the spool valve 112 balances the pressure differential across the spool valve 112.

FIG. 7 shows a schematic view of an exemplary spool valve and H-bridge 118. In some embodiments, the H-bridge 118 may include four switches 120a-d operable to switch the polarity of the pressure differential applied to the load 112. For the H-bridge 118, it is a pair of nozzles 106a-b that act as variable flow restrictors controlled by valve control software.

In some embodiments, the variable flow restrictor creates a pressure differential across the spool 112 as the piezoelectric bendable members 110a-b bend away from the nozzle 106ab to the open position 124. The piezoelectric driver 122 generates a control voltage proportional to the electrical command signal from the valve controller 116 to control the bending of the piezoelectric bendable members 110a-b from their closed positions 126. Thus, fluid flow is less dependent on mechanical components, such as the torque motor, feedback springs, and baffles. A variable flow restrictor is operatively connected to the nozzle. When the two curtain areas are different between the piezoelectric flex member and the nozzle, the variable restrictor creates a pressure differential across the spool valve. The curtain area is defined as the area of the column surface of the jet from the nozzle to the piezoelectric bendable member. Curtain area equation: and pi x D x where D is the nozzle diameter and x is the distance between the nozzle and the piezoelectric bendable member.

In summary, the piezoelectric ring flexure servovalve assembly 100 reduces mechanical wear in aircraft flight control actuation and fuel control systems by removing mechanical components used in prior art servovalves. Pairs of piezoelectric toroidal flexures 110ab are mounted directly adjacent pairs of nozzles 106 a-b. The bendable members independently regulate fluid flow through the nozzles.

In addition, the linear position sensing device 114 measures the spool position and provides feedback to the valve controller regarding the spool position. The valve controller allows the spool valve to move until the valve position reaches the commanded position and the force on the spool valve balances the pressure differential across the spool valve.

In addition, the assembly provides an H-bridge 118 in which the nozzle is a variable flow restrictor controlled by valve control software that creates a pressure differential across the spool valve as the piezoelectric bendable member bends away from the nozzle. Thus, an advantage is that torque motors, dampers, feedback springs, or other moving parts for aircraft flight control actuation and fuel control systems are not used.

These and other advantages of the invention will be further understood and appreciated by those skilled in the art by reference to the following written description, claims and appended drawings.

Since many modifications, variations and changes in detail can be made to the described preferred embodiment of the invention, it is intended that all matter contained in the above description and shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense. Accordingly, the scope of the invention should be determined by the appended claims and their legal equivalents.