Piezoelectric type small-displacement brake actuating device for aviation brake airplane wheel

Abstract

The invention discloses a piezoelectric type small-displacement brake actuating device for an aviation brake airplane wheel, and belongs to the field of aviation brake airplane wheels. Comprising an actuating support, a multi-disc brake assembly and a supporting shell which are coaxially and sequentially arranged. Mounting grooves are distributed in the circumferential direction of the actuating support, and the actuating support is rigidly connected with the three piezoelectric actuating modules through high-strength bolts; the piezoelectric actuation module comprises an upper shell, a lower shell, two orthogonally arranged piezoelectric stacks and a rhombic displacement amplification mechanism; the rhombic displacement amplification mechanism is a rhombic flexible hinge with a double-T-shaped coupling structure; the multi-disc brake assembly comprises movable discs and static discs which are alternately stacked. The supporting shell is of a thin-wall cylinder structure, and one end of the supporting shell is provided with an anti-disengagement skirt edge expanding in the radial direction. Through the modular design of the three piezoelectric actuation modules, the actuation support and the supporting shell, rapid installation and maintenance are achieved, each module can be independently replaced, and the requirements of different machine types are met.

Description

Technical Field

[0001] The present invention belongs to the field of aircraft brake wheels, and in particular relates to a piezoelectric small-displacement brake actuating device for aircraft brake wheels. Background Art

[0002] The aircraft brake wheel is a core component for aircraft landing. It consists of a brake device and a wheel assembly, which are installed together on the aircraft's main landing gear shaft. The wheel assembly is mainly used to bear the weight of the aircraft and support the aircraft, while the brake device is mainly used for aircraft landing braking. The electric brake device is a brake actuator that uses the principle of electric actuation. It is mainly composed of a piezoelectric actuator, an actuator support, a brake housing, a heat storage assembly, etc. At present, full-electric brakes for aircraft wheels have been widely used in the aerospace field due to their advantages such as fast response speed and stable torque. The piezoelectric brake device utilizes the inverse piezoelectric effect when working. When the piezoelectric actuator is energized, the piezoelectric stack is polarized and mechanically deformed under the action of the electric field. The piezoelectric actuator generates displacement and thrust, which presses the brake disc to generate braking torque and stop the aircraft.

[0003] Currently, piezoelectric actuators used in aircraft brake wheels generally employ direct-drive piezoelectric actuators. This structure directly utilizes the inverse piezoelectric effect of piezoelectric ceramics to generate displacement, without any intermediate mechanical amplification. The piezoelectric stack is directly connected to the load, resulting in a compact structure that struggles to meet long travel requirements. Applying traditional direct-drive piezoelectric actuators to small wheels presents structural design challenges and weight constraints. Furthermore, direct-drive piezoelectric actuators have low output force and require high voltage drive under extreme operating conditions, posing the risk of compromising equipment reliability and potentially causing system interference.

[0004] Therefore, the present invention proposes a piezoelectric small-displacement brake actuating device suitable for aircraft wheels. Summary of the Invention

[0005] Technical issues to be solved:

[0006] In order to avoid the shortcomings of the existing technology, the present invention provides a piezoelectric small-displacement brake actuator for aircraft brake wheels. Through the modular design of three piezoelectric actuator modules + actuator support + support shell, rapid installation and maintenance can be achieved. Each module is independently replaceable to adapt to the requirements of different aircraft models; the pressure point actuator module of the device adopts a diamond displacement amplifier to replace the traditional lever or triangular amplification structure, provides deformation allowance through the semi-lunar grooves on the four sides of the diamond, and combines with the double T-head to achieve high-magnification displacement amplification.

[0007] The technical solution of the present invention is: a piezoelectric small-displacement brake actuating device for aircraft brake wheels, comprising an actuating support, a multi-disc brake assembly and a supporting housing coaxially arranged in sequence;

[0008] The actuating support adopts a triangular topological configuration, with mounting slots distributed circumferentially and rigidly connected to the three piezoelectric actuating modules via high-strength bolts. The piezoelectric actuating module comprises an upper housing, a lower housing, two orthogonally arranged piezoelectric stacks, and a diamond-shaped displacement amplification mechanism. The diamond-shaped displacement amplification mechanism is a diamond-shaped flexible hinge with a double T-shaped coupling structure. The upper end of the hinge is embedded in the dovetail groove of the upper housing via a T-shaped tenon, and the lower end of the T-shaped tenon extends to the rectangular through-hole of the lower housing, forming an initial gap of 0.5 mm with the multi-disc brake assembly.

[0009] The multi-disc brake assembly comprises alternately stacked dynamic and static discs, wherein the inner edge of the static disc is provided with a keyway which engages with an axial convex key of the support housing;

[0010] The support shell is a thin-walled cylindrical structure, one end of which is provided with a radially extending anti-slip skirt.

[0011] A further technical solution of the present invention is that the rhombus-shaped flexible hinge has rhombus internal angles of 60° and 120°, respectively, and the long axis direction is orthogonal to the polarization direction of the piezoelectric stack; the wall thickness of the rhombus structure is 2.0 mm, and arc-shaped stress relief grooves are symmetrically provided on its four sides;

[0012] T-shaped tenons are provided on both sides of the rhombus short axis, the cross-sectional dimensions of the upper T-shaped tenon are 10mm×20mm, and the cross-sectional dimensions of the lower T-shaped tenon are 9mm×20mm.

[0013] A further technical solution of the present invention is that the curvature radius of the arc-shaped stress relief groove is 7 mm.

[0014] A further technical solution of the present invention is as follows: the upper shell is a rectangular thin plate part, with a trapezoidal protrusion in the middle of the long side, and a T-shaped dovetail groove is opened on the inner side of the trapezoidal protrusion for mounting the upper T-shaped tenon of the diamond-shaped displacement amplification mechanism; the lower shell is a rectangular parallelepiped with an open top, and a rectangular through hole is opened in the middle of the long side of the bottom, for passing the lower T-shaped tenon of the diamond-shaped displacement amplification mechanism;

[0015] The upper shell is sealed on the open end of the lower shell by 6 M4 fastening screws arranged circumferentially; ears are provided on both sides of the lower shell and fixed to the mounting groove of the actuating support by M4 screws.

[0016] A further technical solution of the present invention is: the material of the diamond displacement amplifier is titanium alloy TC11, and the materials of the upper shell and the lower shell are 05Cr15Ni5Cu4Nb.

[0017] A further technical solution of the present invention is that the piezoelectric stack is packaged from 40 piezoelectric ceramic sheets, the size of a single-layer ceramic sheet is 25mm×25mm×1mm, and the total outer dimensions are 25mm×25mm×40mm.

[0018] A further technical solution of the present invention is: the actuating support is provided with a φ50mm shaft hole along the central axis for interference fit with the landing gear shaft; a distributed strain monitoring hole is provided at the bottom of each mounting groove thereon, with a built-in fiber Bragg grating sensor to monitor local stress distribution in real time.

[0019] A further technical solution of the present invention is: the brake disc assembly includes 3 dynamic brake discs and 4 static brake discs, the outer edge of the dynamic brake disc is provided with 5 key slots, and the inner edge of the static brake disc is provided with 8 key slots, which cooperate with the convex keys of the support shell.

[0020] A further technical solution of the present invention is that the brake actuation device is equipped with a redundant fault-tolerant control system, and when a single piezoelectric actuation module fails, the system automatically switches to a dual-module collaborative working mode.

[0021] A braking method for a piezoelectric small-displacement brake actuator for an aircraft brake wheel, comprising the following specific steps:

[0022] The piezoelectric stacks of the three piezoelectric actuator modules are de-energized, and the diamond-shaped flexible hinge retracts under the action of the preload force, so that an initial gap of 0.5 mm is formed between the T-shaped tenon at the lower end and the multi-disc brake assembly;

[0023] After receiving the braking command, a voltage is applied to the target piezoelectric stack, causing the stack to expand axially. The expansion force drives the diamond-shaped flexible hinge to contract in the long axis direction and output an amplified displacement in the short axis direction.

[0024] The control circuit drives three piezoelectric actuator modules, causing the T-shaped tenons at the lower ends of each diamond-shaped flexible hinge to press against the moving disk, generating an incremental braking torque.

[0025] The fiber Bragg grating sensor is used to monitor the strain of the brake components in real time, calculate the actual brake clearance, and dynamically adjust the driving voltage to ensure that the clearance deviation meets the real-time requirements.

[0026] After the driving voltage is removed, the piezoelectric stack elastically resets due to the disappearance of the inverse piezoelectric effect, and the diamond-shaped flexible hinge retracts to the initial gap position under the action of prestress.

[0027] Beneficial effects

[0028] The beneficial effects of the present invention are as follows: the piezoelectric small-displacement brake actuator structure of the present invention uses an amplifier to convert the output displacement and thrust of the piezoelectric stack and amplify the piezoelectric stack displacement, significantly improving the braking torque and shortening the braking reaction time, making it suitable for braking under extreme aircraft operating conditions. Furthermore, this structure has a small footprint and can further simplify the structure of traditional electric brake devices, reducing the required installation space and product weight. The specific effects are analyzed as follows:

[0029] 1. A diamond-shaped displacement amplifier significantly increases the piezoelectric stack's output thrust through single-stage displacement amplification. Dynamic voltage adjustment based on actual braking torque makes it suitable for emergency braking under extreme aircraft operating conditions.

[0030] 2. The combination of titanium alloy (TC11) and PZT piezoelectric ceramics reduces overall weight. The key and skirt structure of the supporting housing further reduce installation space, making it suitable for micro-wheels and meeting the stringent requirements of the aviation industry for compact layouts. The piezoelectric stack material is traditional lead-based piezoelectric ceramic (PZT), which has a high inverse piezoelectric coefficient and high electromechanical coupling efficiency. The amplifier is made of titanium alloy. The combination of these two materials utilizes the high stiffness of titanium alloy to convert the lateral displacement of the piezoelectric stack into axial output, increasing the amplification factor and meeting lightweight requirements while ensuring stiffness.

[0031] 3. Abandoning the traditional ball screw and gear transmission, relying on the self-resetting characteristics of piezoelectric materials when power is lost, the risk of jamming is completely eliminated. In the modular design, the structure of the electric brake device is simplified and integrated, making it easy to achieve modularization and generalization. The piezoelectric brake device proposed in the present invention can customize the brake thrust and the actuation distance of the piezoelectric actuator module by customizing the size and total thickness of the piezoelectric stack and the size of the amplifier. It can be selected and used according to the performance requirements of the product. It is suitable for the brake devices of large, medium and small aircraft, and the product has strong applicability. The three piezoelectric actuator modules work independently, and the redundancy is better than that of a centralized structure.

[0032] 4. The piezoelectric actuator module connects to the actuator support via a standardized interface (M4 screws), enabling quick assembly and disassembly and replacement. Maintenance requires no disassembly of the entire brake system; ground crew can easily replace the module during routine inspections. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 is an isometric view of a piezoelectric small-displacement brake actuator for an aircraft brake wheel according to an embodiment of the present invention;

[0034] Figure 2 is an axonometric diagram of a piezoelectric actuation module according to an embodiment of the present invention;

[0035] Figure 3 is a cross-sectional view of a piezoelectric actuation module according to an embodiment of the present invention;

[0036] Explanation of the accompanying drawings: 1. Bolt; 2. Piezoelectric actuation module, 21. Upper shell, 22. Piezoelectric stack, 23. Amplifier, 24. Lower shell; 3. Actuation support; 4. Brake disc assembly; 5. Support shell. DETAILED DESCRIPTION

[0037] The embodiments described below with reference to the accompanying drawings are exemplary and are intended to explain the present invention, but should not be construed as limiting the present invention.

[0038] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0039] In recent years, with the continuous development of ferroelectric materials and the continuous progress of piezoelectric actuation technology, amplified piezoelectric actuation modules have emerged as an energy-saving and efficient driving device. The mechanism-amplified piezoelectric actuation module uses the triangular displacement amplification principle to amplify the original displacement of piezoelectric ceramics through mechanical structures such as flexible hinges, levers or parallelogram mechanisms, which can achieve the effects of large magnification, small mechanism volume, and small additional displacement, and can solve the problems of small structural space and limited brake clearance of small and micro main engine wheels. Based on the problems of the prior art, the present invention provides a piezoelectric small-displacement brake actuation device for aircraft brake wheels, characterized in that it includes an actuation support, a multi-disc brake assembly and a support shell that are coaxially arranged in sequence;

[0040] The actuating support adopts a triangular topological configuration, with mounting slots distributed circumferentially and rigidly connected to the three piezoelectric actuating modules via high-strength bolts. The piezoelectric actuating module comprises an upper housing, a lower housing, two orthogonally arranged piezoelectric stacks, and a diamond-shaped displacement amplification mechanism. The diamond-shaped displacement amplification mechanism is a diamond-shaped flexible hinge with a double T-shaped coupling structure. The upper end of the hinge is embedded in the dovetail groove of the upper housing via a T-shaped tenon, and the lower end of the T-shaped tenon extends to the rectangular through-hole of the lower housing, forming an initial gap of 0.5 mm with the multi-disc brake assembly.

[0041] The multi-disc brake assembly comprises alternately stacked dynamic and static discs, wherein the inner edge of the static disc is provided with a keyway which engages with an axial convex key of the support housing;

[0042] The support shell is a thin-walled cylindrical structure, one end of which is provided with a radially extending anti-slip skirt.

[0043] The present invention provides a braking method for a piezoelectric small-displacement brake actuating device for an aircraft brake wheel, which is characterized by the following specific steps:

[0044] The piezoelectric stacks of the three piezoelectric actuator modules are de-energized, and the diamond-shaped flexible hinge retracts under the action of the preload force, so that an initial gap of 0.5 mm is formed between the T-shaped tenon at the lower end and the multi-disc brake assembly;

[0045] After receiving the braking command, a voltage is applied to the target piezoelectric stack, causing the stack to expand axially. The expansion force drives the diamond-shaped flexible hinge to contract in the long axis direction and output an amplified displacement in the short axis direction.

[0046] The control circuit drives three piezoelectric actuator modules, causing the T-shaped tenons at the lower ends of each diamond-shaped flexible hinge to press against the moving disk, generating an incremental braking torque.

[0047] The fiber Bragg grating sensor is used to monitor the strain of the brake components in real time, calculate the actual brake clearance, and dynamically adjust the driving voltage to ensure that the clearance deviation meets the real-time requirements.

[0048] After the driving voltage is removed, the piezoelectric stack elastically resets due to the disappearance of the inverse piezoelectric effect, and the diamond-shaped flexible hinge retracts to the initial gap position under the action of prestress.

[0049] This invention leverages the high amplification power of a diamond-shaped displacement amplifier, a modular design, and a titanium alloy + PZT material combination to achieve the core advantages of lightweight, high reliability, and fast response in the aviation braking field. Compared to existing technologies, its innovations focus on structural optimization and material innovation, addressing the drawbacks of traditional electric brake devices, such as bulk, susceptibility to jamming, and slow response. It demonstrates significant industry leadership and market potential.

[0050] The above technical solution is further described below with reference to the accompanying drawings:

[0051] In one embodiment, referring to Figure 1 As shown, this embodiment of a piezoelectric brake device for an aircraft brake wheel includes a novel structure piezoelectric brake device, which is composed of three piezoelectric actuation modules 2, an actuation support 3, a brake disc assembly 4, a support housing 5, and six bolts 1.

[0052] Reference Figure 2 and Figure 3 As shown, the piezoelectric actuation module 2 is a rectangular parallelepiped structure, consisting of an upper shell 21 , a lower shell 24 , two piezoelectric stacks 22 , and a diamond-shaped displacement amplifier 23 .

[0053] The upper shell 21 is a rectangular thin plate part with a trapezoidal protrusion in the middle. A T-shaped slot is opened on the inner side of the middle of the upper shell for installing the diamond displacement amplifier; two holes are opened on the back for installing screws to fasten the diamond displacement amplifier; one light hole is opened on each trapezoidal inclined surface for routing the cable of the piezoelectric actuation stack during assembly; rectangular slots are opened on the inner sides of both ends of the upper shell for accommodating the piezoelectric stack cable; the upper shell is provided with 6 ears, 2 on each side and 1 on each end, and each ear has a screw hole for connecting to the lower shell.

[0054] The lower shell 24 is a rectangular box body with an open upper end face and a rectangular hole on the lower bottom face for extending the diamond displacement amplifier; the upper end face of the box body is provided with 6 ears, 2 on each side and 1 on each end, each ear has a screw hole for connecting to the upper shell body; two ears are provided in the middle of both sides of the box body, and the ears have screw holes for fixing the piezoelectric actuation module to the actuation support.

[0055] The piezoelectric stack 22 is a rectangular parallelepiped structure, which is a piezoelectric stack composed of more than 40 piezoelectric ceramic sheets packaged together.

[0056] The diamond displacement amplifier 23 is a combination structure of a diamond with double T-heads, wherein the upper T-head is installed in the T-slot of the upper shell and has two screw holes for installing screws for fastening; the lower T-head has no screw holes and is used to move downward and extend to clamp the brake disc under the action of the piezoelectric stack; the left and right ends of the diamond structure are flat, and contact the plane of the piezoelectric stack after the lower shell is installed; there are semi-lunar grooves on the four sides of the diamond to leave space for structural deformation.

[0057] When assembling the piezoelectric actuation module 2, first place the piezoelectric stack into both ends of the groove of the lower shell, then press the upper T-shaped part of the diamond displacement amplifier into the T-slot of the upper shell, and then install a clamping screw on the upper shell to fix it. Then, align the upper shell with the diamond displacement amplifier with the mounting hole cover of the lower shell and cover it on the lower shell, and then fix it with 6 fastening screws.

[0058] The actuating support 3 is a triangular plate-shaped structure, in which a circular connecting hole is provided between the two corners for cooperating with the connecting rod of the landing gear; rectangular mounting grooves are provided on the three corners, and screw holes are provided on both sides of the grooves for installing the electric actuating module in the grooves; a circular hole is provided on the inner circle for connecting to the landing gear shaft; three groups of bolt holes are provided on the outer edge of the step around the circular hole for connecting to the support shell, and each group has two bolt holes.

[0059] The brake disc assembly 4 consists of 3 dynamic brake discs and 4 static brake discs. The inner and outer friction diameters of the dynamic brake disc and the static brake disc are the same. The dynamic brake disc has 5 key slots on the outer edge to meet the cooperation with the wheel assembly, and the static brake disc has 8 key slots on the inner edge to meet the cooperation with the support shell.

[0060] The support shell 5 is a cylindrical structure, divided into a large end and a small end. The small end cooperates with the actuating support and has six bolt mounting holes for installing the piezoelectric actuating module; the cylinder is provided with 8 convex keys for the installation of the static brake disc; the large end of the support shell is designed with a skirt structure to ensure that the brake disc will not fall out after being installed in the support shell.

[0061] In one embodiment, the upper shell 21 is a rectangular thin plate part made of 05Cr15Ni5Cu4Nb. The plate is 3mm thick and 32mm wide. There is a local trapezoidal protrusion in the middle. The length of the protrusion section is 9mm. The angle between the protrusion surface and the plate surface is 45°. The outer dimensions of the upper shell 21 are 115mm×41mm×13mm. Below the trapezoidal protrusion in the middle of the thin plate is a straight horizontal groove with a size of 12mm×32mm×2mm. Below the straight horizontal groove is a straight vertical groove with a size of 5mm×32mm×2mm. The straight horizontal groove and the straight vertical groove form a T-slot, which is used to install a diamond displacement amplifier. There are two φ4mm holes on the back of the middle part of the plate for installing screws to fix the diamond displacement amplifier 23; there is a φ3mm light hole on each trapezoidal inclined surface for routing the cables of the piezoelectric actuation stack during assembly; there are I-shaped horizontal grooves on the inner side of both ends of the upper shell 21 with dimensions of 35mm×4mm×1mm for accommodating the piezoelectric stack cables; the outer end surface of the upper shell 21 is provided with 6 ears with an outer diameter of φ7mm and a φ4mm screw hole, 2 on each side and 1 at each end for connecting to the lower shell.

[0062] In one embodiment, the lower shell 24 is a rectangular box with lugs, made of 05Cr15Ni5Cu4Nb. The upper end of the box is open, and the bottom surface has a 17mm×25mm hole. The outer contour of the box is 108mm×32mm×27mm, and the overall wall thickness is 4mm. The lower shell is equipped with six small lugs with an outer diameter of φ7mm and a φ4mm screw hole. The lugs are 10mm thick, with two on each side and one at each end for connection to the upper shell. Two large lugs are located in the center of each side of the lower shell 24. The large lugs have an outer diameter of φ9mm, an M4 screw hole, and a thickness of 6mm.

[0063] In one embodiment, the piezoelectric stack 22 is a rectangular parallelepiped structure made of PZT, and is composed of 40 piezoelectric ceramic sheets with a size of 25mm×25mm×1mm. The total outer dimensions of the piezoelectric stack are 25mm×25mm×40mm.

[0064] In one embodiment, the diamond displacement amplifier 23 is a combination structure of a diamond with double T-shaped heads, and the material is TC11. The outer contour of the upper end T-shaped head is 10mm×20mm×2mm, and the outer contour of the straight vertical bar is 4mm×20mm×7mm. It is installed in the T-slot of the upper shell. The T-shaped head has two M4 screw holes for fastening with the upper shell; the outer contour of the lower end T-shaped head is 9mm×20mm×4mm, and the outer contour of the straight vertical bar is 6mm×20mm×5mm. It is used to move downward and extend to clamp the brake disc under the action of the piezoelectric stack; the diamond structure is 2mm thick, and the two internal angles are 60° and 120° respectively. The plane dimensions of the left and right ends of the diamond structure are 20mm×5mm. After the lower shell is installed, they are in contact with the plane of the piezoelectric stack; R7mm semicircular grooves are opened on the four sides of the diamond to leave space for structural deformation.

[0065] In one embodiment, when assembling the piezoelectric actuator module 2, the piezoelectric stack 22 is first placed into the two ends of the groove of the lower shell 24, and then the T-shaped part of the diamond displacement amplifier 23 is pressed into the T-slot of the upper shell, and fixed by installing a clamping screw on the upper shell 21. Finally, the upper shell with the diamond displacement amplifier 23 is aligned with the mounting hole cover of the lower shell and fixed on the lower shell with 6 M4 fastening screws.

[0066] In one embodiment, the actuating support 3 is a triangular plate-shaped structure, the material is 05Cr15Ni5Cu4Nb, the plate thickness is 10mm, the maximum outer edge diameter of the triangular vertex is φ240mm, the plate width at the vertex is 60mm, and a groove with a width of 32mm and a depth of 85mm is opened in the middle; a φ72mm boss is provided in the center of the actuating support, and a φ50mm shaft mounting hole is provided in the center of the boss for connection with the landing gear shaft; three groups of bolt holes are evenly distributed around the boss, with 2 M8 bolt holes in each group for connection with the support shell; the actuating support is provided with a connecting rod mounting hole, the outer edge of the connecting rod mounting hole is φ40mm, and a φ20mm through hole is provided for installation in conjunction with the connecting rod of the landing gear.

[0067] In one embodiment, the brake disc assembly 4 comprises three dynamic brake discs and four static brake discs. The dynamic and static brake discs have identical inner and outer friction diameters, with an inner diameter of φ114 mm and an outer diameter of φ206 mm. The dynamic brake discs have five keyways, 4.5 mm wide and 8 mm deep, on their outer edges to ensure proper fit within the wheel assembly. The static brake discs have eight keyways, 15 mm wide and 8 mm deep, on their inner edges to ensure proper fit within the support housing.

[0068] In one embodiment, the support shell 5 is a cylindrical structure, divided into a large end and a small end, the diameter of the large end is φ184mm, the diameter of the small end is φ142mm, and the small end is cooperated with the actuating support to have six M8 bolt mounting holes for installing the piezoelectric actuating module; the cylinder is provided with 8 convex keys with a width of 4mm for the installation of the static brake disc; the large end of the support shell is designed with a skirt structure to ensure that the brake disc will not fall out after being installed in the support shell.

[0069] In one embodiment, when installing the piezoelectric brake device, the three piezoelectric actuating modules are first assembled, and then respectively installed in the three installation slots of the actuating support, and screws are installed in the screw holes on both sides of the slot for tightening; the brake disc assembly is sequentially mounted on the support shell in the order of static brake disc-dynamic brake disc, and then the actuating support equipped with the piezoelectric actuating module is placed on the small end face of the support shell, and the six bolt holes are aligned and the bolts are installed to fix the actuating supports together to complete the installation of the piezoelectric brake device. After installation, the brake clearance between the pressure head of the piezoelectric actuating module and the brake disc is about 0.5 mm.

[0070] During operation, the brake system controls the piezoelectric actuator module to provide power. The ferroelectric material in the piezoelectric stack of the piezoelectric actuator module becomes polarized, generating an inverse piezoelectric effect. The piezoelectric stack undergoes mechanical deformation, providing linear displacement and thrust. The amplifier redirects and amplifies the displacement generated by the piezoelectric stack. The amplifier's pressure head moves downward, pressing against the brake disc to generate frictional torque, braking the wheel. When braking is complete, the piezoelectric actuator module is disconnected from power, the piezoelectric stack's electric field and polarity disappear, mechanical deformation is restored, and the piezoelectric actuator mechanism returns to its original position, driving the pressure head back, releasing the brake.

[0071] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and purpose of the present invention.

Claims

1. A piezoelectric small-displacement brake actuator for aircraft brake wheels, characterized by: It includes an actuating support, a multi-disc brake assembly and a supporting housing that are coaxially arranged in sequence; The actuating support adopts a triangular topological configuration, with mounting slots distributed circumferentially and rigidly connected to the three piezoelectric actuating modules via high-strength bolts. The piezoelectric actuating module comprises an upper housing, a lower housing, two orthogonally arranged piezoelectric stacks, and a diamond-shaped displacement amplification mechanism. The diamond-shaped displacement amplification mechanism is a diamond-shaped flexible hinge with a double T-shaped coupling structure. The upper end of the hinge is embedded in the dovetail groove of the upper housing via a T-shaped tenon, and the lower end of the T-shaped tenon extends to the rectangular through-hole of the lower housing, forming an initial gap of 0.5 mm with the multi-disc brake assembly. The multi-disc brake assembly comprises alternately stacked dynamic and static discs, wherein the inner edge of the static disc is provided with a keyway which engages with an axial convex key of the support housing; The support shell is a thin-walled cylindrical structure, one end of which is provided with a radially extending anti-slip skirt.

2. A piezoelectric small-displacement brake actuator for an aircraft brake wheel according to claim 1, characterized in that: The rhombus-shaped flexible hinge has rhombus internal angles of 60° and 120°, and its long axis is orthogonal to the polarization direction of the piezoelectric stack. The wall thickness of the rhombus structure is 2.0 mm, and arc-shaped stress relief grooves are symmetrically provided on its four sides. T-shaped tenons are provided on both sides of the rhombus short axis, the cross-sectional dimensions of the upper T-shaped tenon are 10mm×20mm, and the cross-sectional dimensions of the lower T-shaped tenon are 9mm×20mm.

3. The piezoelectric small-displacement brake actuator for aircraft brake wheels according to claim 2, characterized in that: The curvature radius of the arc-shaped stress release groove is 7 mm.

4. The piezoelectric small-displacement brake actuator for an aircraft brake wheel according to claim 1, characterized in that: The upper shell is a rectangular thin plate part with a trapezoidal protrusion in the middle of the long side and a T-shaped dovetail groove on the inner side of the trapezoidal protrusion for mounting the upper T-shaped tenon of the diamond-shaped displacement amplification mechanism; the lower shell is a rectangular parallelepiped with an open top and a rectangular through hole in the middle of the long side of the bottom for passing the lower T-shaped tenon of the diamond-shaped displacement amplification mechanism; The upper shell is sealed on the open end of the lower shell by 6 M4 fastening screws arranged circumferentially; ears are provided on both sides of the lower shell and fixed to the mounting groove of the actuating support by M4 screws.

5. The piezoelectric small-displacement brake actuator for aircraft brake wheels according to claim 4, characterized in that: The material of the diamond displacement amplifier is titanium alloy TC11, and the materials of the upper shell and the lower shell are 05Cr15Ni5Cu4Nb.

6. The piezoelectric small-displacement brake actuator for aircraft brake wheels according to claim 1, characterized in that: The piezoelectric stack is packaged from 40 piezoelectric ceramic sheets, the size of a single-layer ceramic sheet is 25 mm × 25 mm × 1 mm, and the total outer dimensions are 25 mm × 25 mm × 40 mm.

7. The piezoelectric small-displacement brake actuator for aircraft brake wheels according to claim 1, characterized in that: The actuating support has a φ50mm shaft hole along the central axis for interference fit with the landing gear shaft; the bottom of each mounting groove is provided with a distributed strain monitoring hole with a built-in fiber Bragg grating sensor to monitor the local stress distribution in real time.

8. The piezoelectric small-displacement brake actuator for aircraft brake wheels according to claim 1, characterized in that: The brake disc assembly includes 3 dynamic brake discs and 4 static brake discs. The outer edge of the dynamic brake disc is provided with 5 key slots, and the inner edge of the static brake disc is provided with 8 key slots, which cooperate with the convex keys of the support shell.

9. The piezoelectric small-displacement brake actuator for aircraft brake wheels according to claim 1, characterized in that: The brake actuation device is equipped with a redundant fault-tolerant control system. When a single piezoelectric actuation module fails, the system automatically switches to a dual-module collaborative working mode.

10. A braking method for a piezoelectric small-displacement brake actuator for an aircraft brake wheel according to any one of claims 1 to 9, characterized in that The specific steps are as follows: The piezoelectric stacks of the three piezoelectric actuator modules are de-energized, and the diamond-shaped flexible hinge retracts under the action of the preload force, so that an initial gap of 0.5 mm is formed between the T-shaped tenon at the lower end and the multi-disc brake assembly; After receiving the braking command, a voltage is applied to the target piezoelectric stack, causing the stack to expand axially. The expansion force drives the diamond-shaped flexible hinge to contract in the long axis direction and output an amplified displacement in the short axis direction. The control circuit drives three piezoelectric actuator modules, causing the T-shaped tenons at the lower ends of each diamond-shaped flexible hinge to press against the moving disk, generating an incremental braking torque. The fiber Bragg grating sensor is used to monitor the strain of the brake components in real time, calculate the actual brake clearance, and dynamically adjust the driving voltage to ensure that the clearance deviation meets the real-time requirements. After the driving voltage is removed, the piezoelectric stack elastically resets due to the disappearance of the inverse piezoelectric effect, and the diamond-shaped flexible hinge retracts to the initial gap position under the action of prestress.

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