Piezoelectric APU stop device

Abstract

The application discloses a piezoelectric APU stop device and relates to the technical field of aircraft power devices.The device comprises a shell, which is sequentially provided with a piezoelectric module, an actuating block, a pressing disc, a moving disc and a pressure receiving disc from the bottom; the piezoelectric module is provided with lead wires of positive and negative electrodes, which are led out from corresponding holes; the actuating block is arranged on the end face of the piezoelectric module; the pressure receiving disc is fixed on the shell; coaxial pivots are arranged at the central positions of the end faces of the moving disc; one pivot penetrates the center of the pressing disc, and the other pivot penetrates the center of the pressure receiving disc and extends to the outside of the pressure receiving disc.The piezoelectric stop device utilizes the inverse piezoelectric effect of piezoelectric materials; after the piezoelectric module is electrified, deformation displacement and thrust are generated, braking torque is generated by pressing the brake disc, and the APU main shaft is stopped from rotating.

Description

Technical Field

[0001] This invention relates to the field of aircraft power plant technology, and specifically to a piezoelectric APU stop device. Background Technology

[0002] In aircraft propulsion systems, the APU (Auxiliary Power Unit) provides power, air, and hydraulic power, playing a crucial role in aircraft operation. However, currently, the APU rotor cannot autonomously stop in the air after startup and shutdown. Continuous high-speed rotor movement causes abnormal wear and failure of the terminal one-way clutch, leading to APU malfunction and affecting its lifespan. Therefore, a stopping device is needed to prevent interference with the APU's normal operation during APU operation and to provide a stopping torque to halt the APU's main shaft when the APU stops. A hydraulic APU stopper already exists, installed within the APU structure; however, its complex structure poses a risk of seal leakage. The hydraulic seal and return mechanism are structurally complex. Furthermore, this mechanism shares a hydraulic power source with the aircraft, making it susceptible to hydraulic pressure fluctuations during stopping. Additionally, its current weight hinders its widespread adoption in aircraft fleets. Summary of the Invention

[0003] To address the shortcomings of the aforementioned background technology, this invention provides a piezoelectric APU stop device. Primarily based on the piezoelectric stop, which utilizes the inverse piezoelectric effect of piezoelectric materials, the piezoelectric module generates deformation displacement and thrust after being energized, pressing the brake disc to generate braking torque and stopping the APU spindle from rotating. This piezoelectric APU stop device can solve the problems of large weight, complex structure, and susceptibility to sealing leaks in hydraulic APU stop devices.

[0004] The first objective of this invention is to provide a piezoelectric APU stop device, comprising: The housing is a cylindrical structure, and from the bottom up, the housing is sequentially provided with a piezoelectric module, an actuator block, a clamping plate, a moving plate, and a pressure plate. A shaft is provided at the bottom of the housing, and two holes are formed therein. The shaft and the housing are on the same axis. The piezoelectric module is a columnar structure of stacked piezoelectric ceramics with a through hole in the middle; the through hole of the piezoelectric module is matched with the shaft, and the bottom of the piezoelectric module is provided with leads for the positive and negative electrodes, which are led out from the corresponding holes; The actuator block is disposed on the end face of the piezoelectric module; The clamping plate is provided with multiple keyways at equal intervals around its circumference, and the inner wall of the housing is provided with multiple keys corresponding to the keyways; each keyway on the clamping plate passes through a key inside the housing; The pressure plate is fixed to the housing; Both sides of the moving plate are provided with a coaxial pivot at the center. One pivot passes through the center of the pressing plate, and the other pivot passes through the center of the bearing plate and extends to the outside of the bearing plate.

[0005] Preferably, when the APU is working, the APU shaft drives the pivot extending to the outside of the pressure plate to rotate, and drives the moving plate to rotate. At this time, the piezoelectric module does not supply power, and the pressure plate and the pressure plate are connected to the housing and do not move. When the APU stops working and the APU shaft needs to be stopped, power is supplied to the piezoelectric module through the leads of the positive and negative electrodes. Under the action of the electrodes, the piezoelectric module utilizes the polarization characteristics of ferroelectric materials to generate mechanical deformation after being energized, pushing the actuator block forward, causing the pressure plate to press against the rotating moving plate, and then against the bearing plate. A stopping torque is generated between the rotating moving plate and the stationary pressure plate and bearing plate, causing the APU shaft to stop.

[0006] Preferably, after the piezoelectric module is powered off, the stacked electric field and magnetism disappear, the piezoelectric module returns to its original state, and the actuator returns to its original position.

[0007] Preferably, both end faces of the moving disc are relatively convex conical surfaces, and the end faces of the pressing disc and the bearing disc corresponding to the convex conical surfaces are both inwardly concave conical surfaces.

[0008] Preferably, both the pressing plate and the bearing plate have a through hole in the center for the pivot to pass through; A cover plate is provided on the side of the pressure plate away from the moving plate, and the cover plate is fixed to the housing by bolts around its perimeter; threaded holes for bolts are provided on the side wall of the housing. The pressure plate and the cover plate are machined as one piece and do not rotate with the moving plate.

[0009] Preferably, the housing, piezoelectric module, actuator, clamping plate, moving plate, and bearing plate are all coaxial.

[0010] Preferably, the bottom of the piezoelectric module is adhered to the bottom of the housing by applying J88 adhesive; The bottom of the actuator is a ring, and there is a raised ring structure on the surface of the ring; The flat surface of the back of the actuator ring is coated with J88 adhesive, and the actuator is then attached to the piezoelectric module.

[0011] Preferably, the piezoelectric module is made of PZT; the actuator is made of 05Cr15Ni5Cu4Nb stainless steel. The material of the moving disc is 25Cr2MoVA.

[0012] The second objective of this invention is to provide a method for installing a piezoelectric APU stop device, comprising: First, install the piezoelectric module into the housing. The piezoelectric module has a hole in the middle that mates with the shaft at the bottom of the housing. The hole in the piezoelectric module should pass through the shaft at the bottom of the housing. The piezoelectric ceramic at the bottom of the piezoelectric module is equipped with positive and negative electrode leads. Before assembly, J88 adhesive is applied to the bottom and the module is attached to the bottom of the housing. During installation, the positive and negative wires are led out from the holes at the bottom of the housing. After installing the piezoelectric module, install the actuator. Apply J88 adhesive to the back surface of the actuator and attach it to the piezoelectric module. Then install the clamping plate. The keyway on the clamping plate should correspond one-to-one with the key inside the housing and pass through the key inside the housing. Then install the moving plate, whose pivot should pass through the pressure plate; Finally, install the pressure plate. The hole in the middle of the pressure plate passes through the pivot of the moving plate, and the pressure plate is fixed to the housing to ensure that the pressure plate does not rotate with the moving plate. The piezoelectric stop device for the APU is now assembled. Install the stop device onto the APU spindle.

[0013] This invention provides a piezoelectric APU stop device, which has the following advantages compared with existing hydraulic APU stop devices: This device is smaller and lighter. The piezoelectric APU stop device proposed in this invention abandons the traditional hydraulic transmission method and uses a lighter ceramic piezoelectric module to replace the original hydraulic sealing structure, spring return mechanism, and hydraulic cylinder. Compared with the previous metal mechanical structure, the stop is lighter and smaller, and the piezoelectric device does not require a return mechanism, reducing the metal return mechanism in the traditional hydraulic device, resulting in a 17% reduction in volume and a 40% reduction in weight.

[0014] The stopping performance is more stable. The working stability of hydraulic APU stoppers is affected by two factors. First, hydraulic APU stoppers share the aircraft's hydraulic power source, and their working pressure is easily affected by disturbances, resulting in unstable performance. Second, hydraulic APU stoppers have a complex structure and small mechanical clearances, making hydraulic moving parts susceptible to contamination from hydraulic system contaminants and brake dust backflow, which can cause the APU to lose pressure or mechanically jam, losing its stopping function. Piezoelectric APU stoppers do not use a hydraulic structure and are not affected by pressure fluctuations in the hydraulic power source. Furthermore, they do not use hydraulic actuating parts, resulting in larger clearances that prevent jamming due to foreign matter trapped in the clearances or blockage of the hydraulic channels.

[0015] Higher operational reliability. The piezoelectric APU stop device proposed in this invention uses a piezoelectric module as its actuating component. Hundreds of piezoelectric plates within the module undergo mechanical displacement when energized, providing output stroke and clamping force. The failure of a single piezoelectric plate will not affect the overall output capability of the piezoelectric module, resulting in higher reliability. In contrast, with traditional hydraulic APU stop devices, damage to the spring or any other component will render the entire device inoperable.

[0016] Greater maintainability. The piezoelectric APU stop device proposed in this invention significantly simplifies the structure of the stop device. The actuating block, piezoelectric module, and housing are fixed by adhesive. Under the action of the piezoelectric module expanding when energized and contracting when de-energized, the actuating block extends and retracts, resulting in a simpler structure. The number of parts in the entire assembly is reduced from 24 to 10, significantly reducing disassembly and inspection time. At the same time, the piezoelectric module, as the main structure, adopts a modular design, simplifying field maintenance and enabling field-level repairs. This solves the problem of hydraulic structures requiring base-level repairs, greatly reducing maintenance cycles and significantly improving maintainability.

[0017] The device offers stable and safe operation with high control precision. Utilizing the polarization properties of ferroelectric materials, the piezoelectric braking device for aircraft wheels, as proposed in this invention, exhibits mechanical deformation upon energization and returns to its original position upon de-energization, ensuring stable operation. The piezoelectric module comprises multiple piezoelectric ceramic pieces, resulting in a stable and precise total actuation distance. Attached Figure Description

[0018] Figure 1 This is a two-dimensional cross-sectional view of the piezoelectric stop device of the APU; The components include: 1. Housing; 2. Piezoelectric module; 3. Actuator; 4. Pressure plate; 5. Moving plate; 6. Pressure plate; 7. Bolt; Figure 2 This is a 3D simulation view of the piezoelectric stop device of the APU; Figure 3 This is a 3D exploded view of the piezoelectric stop device of the APU; The components include: 1. Housing; 2. Piezoelectric module; 3. Actuator; 4. Pressure plate; 5. Moving plate; 6. Pressure plate; 7. Bolt; Figure 4 It is a 3D simulation view of the shell; Figure 5 This is a two-dimensional sectional view of the shell; Figure 6 It is a 3D simulation view of the actuator; Figure 7 This is a two-dimensional sectional view of the actuator block; Figure 8 It is a 3D simulation view of the pressure plate; Figure 9 This is a two-dimensional sectional view of the pressure plate; Figure 10 It is a 3D simulation view of the moving disk; Figure 11 This is a two-dimensional sectional view of the moving disk; Figure 12 This is a 3D simulation view of the pressure plate; Figure 13 It is a two-dimensional sectional view of the pressure plate. Detailed Implementation

[0019] To enable those skilled in the art to better understand and implement the technical solutions of the present invention, the present invention will be further described below in conjunction with specific embodiments and accompanying drawings. However, the embodiments described are not intended to limit the present invention.

[0020] The purpose of this invention is to provide a piezoelectric APU stop device for APU auxiliary power units. Compared with traditional hydraulic APU stop devices, it can reduce the weight of the APU stop device, avoid the instability of braking performance caused by hydraulic fluctuations, simplify the structure and improve working reliability, improve maintainability, shorten maintenance time, and avoid problems such as hydraulic seal leakage.

[0021] See Figures 1-13 As shown, a piezoelectric APU stop device includes a housing 1, a piezoelectric module 2, an actuating block 3, a clamping plate 4, a moving plate 5, a bearing plate 6, and three bolts 7. The bolts are standard parts. A two-dimensional sectional view of the piezoelectric APU stop device is shown below. Figure 1 As shown, the 3D simulation view is as follows: Figure 2 As shown, the 3D exploded view is as follows Figure 3 As shown. The 3D simulation diagram of the shell is as follows. Figure 4 As shown, the sectional view of the shell is as follows Figure 5 As shown. The 3D simulation view of the actuator is as follows. Figure 6 As shown, the two-dimensional sectional view is as follows Figure 7 As shown in the figure. The 3D simulation diagram of the clamping plate is as follows. Figure 8 As shown, the two-dimensional sectional view is as follows Figure 9 As shown. The 3D simulation diagram of the moving disk is as follows. Figure 10 As shown, the two-dimensional sectional view is as follows Figure 11 As shown in the figure. The 3D simulation diagram of the pressure plate is as follows. Figure 12 As shown, the two-dimensional sectional view is as follows Figure 13 As shown.

[0022] The piezoelectric APU stop device includes a housing 1, and the housing 1 is provided with a piezoelectric module 2, an actuating block 3, a clamping plate 4, a moving plate 5 and a bearing plate 6 arranged sequentially from the bottom. The shell 1 is a cylindrical structure; a shaft 12 is provided at the bottom inside the shell 1, and two holes 11 are opened therein, and the shaft 12 is on the same axis as the shell 1; The piezoelectric module 2 is a columnar structure of stacked piezoelectric ceramics with a through hole in the middle; the through hole of the piezoelectric module 2 is matched with the shaft 12, and the bottom of the piezoelectric module 2 is provided with positive and negative electrode leads, which are led out from the corresponding holes 11; The actuator 3 is disposed on the end face of the piezoelectric module 2; The pressing plate 4 is provided with multiple keyways at equal intervals around its circumference, and the inner wall of the housing 1 is provided with multiple keys 13 corresponding to the keyways; each keyway on the pressing plate 4 passes through the key 13 inside the housing 1; The pressure plate 6 is fixed to the housing 1; Both sides of the moving plate 5 are provided with a coaxial pivot at the center of their respective end faces. One pivot passes through the center of the pressing plate 4, and the other pivot passes through the center of the bearing plate 6 and extends to the outside of the bearing plate 6.

[0023] The device provided by this invention, when the APU is working, drives the pivot extending to the outside of the pressure plate 6 to rotate, and drives the moving plate 5 to rotate. At this time, the piezoelectric module 2 is not powered, and the pressure plate 4 and the pressure plate 6 are connected to the housing 1 and do not move. After the APU stops working, when the APU shaft needs to be stopped, power is supplied to the piezoelectric module 2 through the leads of the positive and negative electrodes. Under the action of the electrodes, the piezoelectric module 2 utilizes the polarization characteristics of ferroelectric materials to generate mechanical deformation after being energized, pushing the actuator 3 forward. This causes the pressure plate 4 to press against the rotating moving plate 5, and then against the pressure plate 6. A stopping torque is generated between the rotating moving plate 5 and the stationary pressure plate 4 and pressure plate 6, stopping the APU shaft. After the piezoelectric module 2 is de-energized, the stacked electric field and magnetism disappear, the piezoelectric module 2 returns to its original state, and the actuator 3 returns to its original position.

[0024] In this embodiment, see Figure 4 and Figure 5 As shown, the housing 1 is made of 30CrMnSiA material, with a total length of 89mm, a lower diameter of Φ50mm and a length of 50.5mm, an upper diameter of Φ54mm and a length of 38.5mm, and a wall thickness of 2mm. The upper end of the housing has three annular bosses, each Φ10mm in diameter and 15mm high, arranged circumferentially at 120°. Each boss has a through hole at its center, concentric with the boss, and threaded with MJ 4×0.7 threads. The bosses can connect to the pressure plate to prevent rotation. The upper interior of the housing has five raised keys for circumferentially fixing the pressure plate. These keys are 19mm from the housing opening, with a length of 10mm, a width of 4mm, and a height of 2.5mm. The bottom center of the housing has a raised shaft with a diameter of Φ10mm and a height of 52mm, used for circumferentially fixing the piezoelectric module 2. There are two through holes at the bottom of the shell, each with a diameter of Φ6mm, 15mm from the center of the shell, and they are symmetrical at 180°.

[0025] See Figure 6and Figure 7 As shown, the bottom of the actuator block 3 is a ring, and there is a raised ring structure on the surface of the ring; the flat surface on the back of the ring of the actuator block 3 is coated with J88 adhesive, and the actuator block 3 is attached to the piezoelectric module 2.

[0026] To ensure stable rotation of the moving disc, both end faces of the moving disc 5 are relatively convex conical surfaces, while the end faces of the pressure plate 4 and the bearing plate 6, corresponding to the convex conical surfaces, are inwardly concave conical surfaces. A through hole for a pivot to pass through is provided in the center of both the pressure plate 4 and the bearing plate 6; this allows the pivots on both sides of the moving disc 5 to rotate at the corresponding through holes, thereby ensuring stable rotation of the moving disc.

[0027] The pressure plate 6 is provided with a cover plate on the side away from the moving plate 5, and the cover plate is fixed to the housing 1 by bolts 7 around its perimeter; the side wall of the housing 1 is provided with threaded holes for bolting the bolts 7; the pressure plate 6 and the cover plate are machined as one piece and do not rotate with the moving plate 5.

[0028] See Figure 8 and Figure 9 As shown, the clamping disc 4 is sintered from a clamping disc skeleton 4-1 and three powder metallurgy discs 4-2. The clamping disc skeleton is annular, made of 1Cr18Ni9 material, with dimensions of Φ48.5mm × Φ15mm × 2.5mm. Five keyways are evenly distributed around the circumference of the annulus, each 4.5mm wide and 1.5mm deep. These keyways need to mate with five raised keys on the shell. Three iron-based powder metallurgy discs are sintered onto the skeleton. Each powder metallurgy disc is fan-shaped, with an outer radius of R20mm, an inner radius of R8mm, and a trapezoidal thickness, with the trapezoidal angle forming a 30° angle with the vertical direction. A 3mm gap should be left between the three discs to prevent interference from thermal expansion of the powder metallurgy material after friction. The disc surface of the clamping disc should mate with the disc surface of the moving disc.

[0029] See Figure 11 and Figure 12 As shown, the moving disc 5 is made of 25Cr2MoVA. The moving disc is connected to the main shaft via a spline and rotates with the main shaft. The moving disc is a one-piece design. The outer diameter of the moving disc is Φ43mm, and the disc surface is trapezoidal (a raised conical surface), 4mm wide in the middle, with each side forming a 30° angle with the vertical direction. A hollow shaft is located in the middle, with an outer diameter of Φ14mm and an inner diameter of 7mm. Six rectangular grooves are cut on the shaft, each 2mm wide and 1mm deep. The two ends of the shaft have different lengths: the longer side is 24mm long, and the shorter side is 5mm long. The longer side passes through the pressure plate, and the shorter side passes through the clamping plate.

[0030] See Figure 12 and Figure 13As shown, the pressure plate 6 is sintered from a clamping plate frame 6-1 (cover plate) and three powder metallurgy discs 6-2. The clamping plate frame is a one-piece design, made of 1Cr18Ni9 material, with a bottom ring-shaped structure measuring Φ54mm×Φ15mm×2mm, and three Φ10mm annular bosses evenly distributed around its circumference. The bosses are arranged at 120° circumferences, with a through hole at the center of each boss, having a diameter of Φ4.5mm. Three iron-based powder metallurgy discs are sintered on the pressure plate. The powder metallurgy discs are fan-shaped, with an outer radius of R20mm, an inner radius of R8mm, and a trapezoidal shape in the thickness direction, with the trapezoidal angle forming a 30° angle with the vertical direction. A 3mm gap should be left between the three discs to prevent interference caused by thermal expansion of the powder metallurgy material after friction. The surface of the clamping plate should mate with the surface of the moving plate.

[0031] For example, there are 3 bolts 7 for fixing the cover plate, with bolt code GJB 3374 / 2-4×17 / HB0-9-A, which are mature standard parts.

[0032] The housing 1 is coaxial with the piezoelectric module 2, the actuator 3, the clamping plate 4, the moving plate 5, and the pressure plate 6.

[0033] The bottom of the piezoelectric module 2 is attached to the bottom of the housing 1 by applying J88 adhesive; The piezoelectric module 2 is a ring-shaped cylindrical structure made of PZT. It is a piezoelectric stack consisting of 50 individual piezoelectric ceramic sheets with a specification of Φ44mm×Φ10.5mm×1mm. The total outer dimensions of the piezoelectric stack are Φ44mm×Φ10.5mm×50mm.

[0034] The actuator block 3 is made of 05Cr15Ni5Cu4Nb stainless steel. The actuator block 3 is an integral design with a circular bottom, measuring Φ44mm×Φ10.5mm×5mm. There is a raised ring structure on the surface of the ring, which is used to transmit the pressure transmitted by the piezoelectric module, measuring Φ27mm×Φ32mm×5mm.

[0035] This invention provides a method for installing a piezoelectric APU stop device, comprising: First, install the piezoelectric module 2 into the housing 1. The piezoelectric module 2 has a hole in the middle that mates with the shaft at the bottom of the housing 1. The hole in the piezoelectric module 2 should pass through the shaft at the bottom of the housing 1. The piezoelectric ceramic at the bottom of the piezoelectric module 2 is equipped with positive and negative electrode leads. Before assembly, J88 adhesive is applied to the bottom and it is attached to the bottom of the housing 1. During installation, the positive and negative wires are led out from the holes at the bottom of the housing. After installing the piezoelectric module 2, install the actuator 3. Apply J88 adhesive to the back surface of the actuator 3 and stick the actuator 3 onto the piezoelectric module 2. Then install the clamping plate 4. The keyway on the clamping plate 4 should correspond one-to-one with the key 13 inside the housing 1 and pass through the key 13 inside the housing 1. Then install the moving plate 5, whose pivot should pass through the clamping plate 4; Finally, install the pressure plate 6. The hole in the middle of the pressure plate 6 passes through the pivot of the moving plate 5, and fix the pressure plate 6 to the housing to ensure that the pressure plate does not rotate with the moving plate. The piezoelectric stop device for APU is now assembled. Install the stop device onto the APU spindle.

[0036] For example, in the piezoelectric APU stop device, first install the piezoelectric module 2 into the housing 1. The piezoelectric module 2 is a columnar structure of stacked piezoelectric ceramics with a hole in the middle, which mates with the shaft at the bottom of the housing 1. The hole of the piezoelectric module 2 should pass through the shaft at the bottom of the housing 1. The piezoelectric ceramics at the bottom of the piezoelectric module 2 are equipped with positive and negative electrode leads. Before assembly, apply J88 adhesive to the bottom and stick it to the bottom of the housing. During installation, ensure that the positive and negative electrode leads of the piezoelectric module are led out from the hole at the bottom of the housing. After installing the piezoelectric module 2, install the actuating block 3. Before installing the actuating block 3, apply J88 adhesive to the flat surface on the back of the actuating block 3 and stick it to the piezoelectric module 2. Then install the pressure plate 4. The keyways on the pressure plate should correspond one-to-one with the keys inside the housing and pass through the keys inside the housing. Then install the moving plate, whose shaft should pass through the pressure plate. Finally, install the pressure plate. The hole in the center of the pressure plate passes through the shaft of the moving plate, and align the three holes on the pressure plate with the three holes on the housing. Connect them with bolt 7 to ensure the pressure plate does not rotate with the moving plate. The piezoelectric stop device for the APU is now assembled. Install the stop device onto the APU spindle.

[0037] During installation, first assemble the piezoelectric module 2. Apply J88 adhesive to the last piezoelectric ceramic piece and bond the piezoelectric module 2 to the housing 1. During assembly, the positive and negative electrode wires should pass through the holes in the housing. Next, install the actuator block 3. Apply J88 adhesive to the annular bottom surface of the actuator block 3 and attach it to the piezoelectric ceramic. Install the clamping plate 4 into the housing 1, aligning the five keyways of the clamping plate 4 with the five keys on the housing 1. Install the moving plate 5, inserting the shorter side of the shaft into the hole of the clamping plate 4. Install the pressure plate 6. The hole in the pressure plate should pass through the moving plate 5, and the three annular steps of the pressure plate should correspond one-to-one with the annular steps of the housing. Finally, install and tighten the three bolts (GJB 3374 / 2-4×17 / HB 0-9-A). After the piezoelectric braking device is installed, insert the APU shaft into the piezoelectric stop device and connect the electrodes; it is then ready for use. When the APU is working, the spindle drives the moving disk 5 to rotate at high speed. At this time, the piezoelectric module 2 is not powered and does not work, and the clamping disk 4 and the bearing disk 6 are connected to the housing 1 and do not move. After the APU stops working, when the APU shaft needs to be stopped, power is supplied to the piezoelectric module 2. Under the action of the electrodes, the piezoelectric module 2 utilizes the polarization characteristics of ferroelectric materials to produce mechanical deformation after being energized. This pushes the actuator block 3 forward. The gap between the actuator block 3 and the clamping disk is about 0.5mm. The stroke of the piezoelectric actuator block is greater than this gap, causing the clamping disk 4 to press against the high-speed rotating moving disk, and then against the bearing disk 6. A stopping torque is generated between the rotating moving disk 1 and the stationary clamping disk 4 and bearing disk 6, stopping the APU shaft. After the piezoelectric module 2 is de-energized, the stacked electric field and magnetism disappear, the piezoelectric module 2 returns to its original state, and the actuator block 3 returns to its original position, releasing the brake.

[0038] This invention describes preferred embodiments and their effects. However, those skilled in the art, once they understand the basic inventive concept, can make other changes and modifications to these embodiments.

[0039] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A piezoelectric APU stop device, characterized in that, include: The shell (1) is a cylindrical structure. From the bottom, the shell (1) is provided with a piezoelectric module (2), an actuator (3), a clamping plate (4), a moving plate (5) and a pressure plate (6). The bottom of the housing (1) is provided with a shaft (12) and two holes (11) are provided. The shaft (12) and the housing (1) are on the same axis. The piezoelectric module (2) is a columnar structure of stacked piezoelectric ceramics with a through hole in the middle; the through hole of the piezoelectric module (2) is matched with the shaft (12), and the bottom of the piezoelectric module (2) is provided with leads for positive and negative electrodes, which are led out from the corresponding holes (11); The actuator (3) is disposed on the end face of the piezoelectric module (2); The clamping plate (4) is provided with multiple keyways at equal intervals around its circumference, and the inner wall of the housing (1) is provided with multiple keys (13) corresponding to the keyways; each keyway on the clamping plate (4) passes through the key (13) inside the housing (1). The pressure plate (6) is fixed to the housing (1); Both sides of the moving plate (5) are provided with a coaxial pivot at the center of the end face. One pivot passes through the center of the pressing plate (4), and the other pivot passes through the center of the bearing plate (6) and extends to the outside of the bearing plate (6).

2. The piezoelectric APU stop device according to claim 1, characterized in that, When the APU is working, the APU shaft drives the pivot extending to the outside of the pressure plate (6) to rotate, and drives the moving plate (5) to rotate. At this time, the piezoelectric module (2) does not supply power, and the pressure plate (4) and the pressure plate (6) are connected to the housing (1) and do not move. When the APU stops working and the APU shaft needs to be stopped, power is supplied to the piezoelectric module (2) through the leads of the positive and negative electrodes. Under the action of the electrodes, the piezoelectric module (2) utilizes the polarization characteristics of ferroelectric materials to generate mechanical deformation after being energized, pushing the actuator (3) to move forward, so that the clamping plate (4) presses against the rotating moving plate (5), and then against the bearing plate (6). The rotating moving plate (5) and the stationary clamping plate (4) and bearing plate (6) generate a stopping torque, which stops the APU shaft.

3. The piezoelectric APU stop device according to claim 2, characterized in that, After the piezoelectric module (2) is de-energized, the stacked electric field and magnetism disappear, the piezoelectric module (2) returns to its original state, and the actuator (3) returns to its original position.

4. The piezoelectric APU stop device according to claim 1, characterized in that, Both sides of the moving plate (5) are relatively convex conical surfaces, and the end faces of the pressing plate (4) and the bearing plate (6) corresponding to the convex conical surfaces are inwardly concave conical surfaces.

5. The piezoelectric APU stop device according to claim 1, characterized in that, Both the pressing plate (4) and the bearing plate (6) have through holes in the center for the pivot to pass through; The pressure plate (6) is provided with a cover plate on the side away from the moving plate (5), and the cover plate is fixed to the housing (1) by bolts (7) around its perimeter; the side wall of the housing (1) is provided with threaded holes for bolts (7); The pressure plate (6) is machined as a whole with the cover plate and does not rotate with the moving plate (5).

6. The piezoelectric APU stop device according to claim 1, characterized in that, The housing (1) is coaxial with the piezoelectric module (2), the actuating block (3), the clamping plate (4), the moving plate (5), and the pressure plate (6).

7. The piezoelectric APU stop device according to claim 1, characterized in that, The bottom of the piezoelectric module (2) is attached to the bottom of the housing (1) by applying J88 adhesive; The bottom of the actuating block (3) is a ring, and there is a raised ring structure on the surface of the ring; The back surface of the actuating block (3) is coated with J88 adhesive, and the actuating block (3) is attached to the piezoelectric module (2).

8. The piezoelectric APU stop device according to claim 1, characterized in that, The piezoelectric module (2) is made of PZT; the actuator (3) is made of 05Cr15Ni5Cu4Nb stainless steel. The material of the moving disk (5) is 25Cr2MoVA.

9. A method for installing the piezoelectric APU stop device according to any one of claims 1 to 8, characterized in that, include: First, install the piezoelectric module (2) into the housing (1). The piezoelectric module (2) has a hole in the middle that mates with the shaft at the bottom of the housing (1). The hole in the piezoelectric module (2) should pass through the shaft at the bottom of the housing (1). The piezoelectric ceramic at the bottom of the piezoelectric module (2) is equipped with positive and negative electrode leads. Before assembly, the bottom is coated with J88 adhesive and glued to the bottom of the housing (1). During installation, the positive and negative wires are led out from the holes at the bottom of the housing. After installing the piezoelectric module (2), install the actuator (3). Apply J88 adhesive to the back surface of the actuator (3) and attach the actuator (3) to the piezoelectric module (2). Then install the clamping plate (4). The keyway on the clamping plate (4) should correspond one-to-one with the key (13) inside the housing (1) and pass through the key (13) inside the housing (1). Then install the moving plate (5), whose pivot should pass through the pressure plate (4); Finally, install the bearing plate (6). The hole in the middle of the bearing plate (6) passes through the pivot of the moving plate (5) and fixes the bearing plate (6) to the housing to ensure that the bearing plate does not rotate with the moving plate. The piezoelectric stop device for APU is now assembled. Install the stop device onto the APU spindle.

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