Rapid mechanical switch of flexible bistable mechanism driven by ultrasonic motor

Abstract

The invention discloses a rapid mechanical switch of a flexible bistable mechanism driven by an ultrasonic motor, which is characterized in that an active slide block is driven by the ultrasonic motor through a friction strip to do reciprocating rectilinear motion, and a moving contact and a static contact of the flexible bistable mechanism are driven to be in contact with and separated from each other. Wherein the ultrasonic motor has the advantages of being high in response speed, large in thrust and good in environmental adaptability, and the flexible bistable mechanism can spontaneously generate displacement without inputting displacement after limited displacement is input. The rapid and continuous force output of the ultrasonic motor enables the flexible bistable mechanism to generate larger displacement in a short time. According to the invention, through combination of the ultrasonic motor and the flexible bistable mechanism, the mechanical switch which is short in on-off time, simple in structure and good in environmental adaptability is realized.

Description

Technical Field

[0001] This invention relates to the field of mechanical switches, and in particular to a fast mechanical switch with an ultrasonic motor-driven flexible bistable mechanism that can be used in airborne medium-voltage DC system hybrid circuit breakers. Background Technology

[0002] Mechanical circuit breakers have low resistance in the on-state but long operating time and difficulty achieving zero current crossing under DC conditions. Solid-state circuit breakers have short operating time and reliable operation, but they incur significant losses, are difficult to withstand harsh environments, and may cause electromagnetic compatibility issues. Hybrid circuit breakers, combining the advantages of the first two types, have become a popular research area.

[0003] Mechanical switches in hybrid circuit breakers play a crucial role in providing low-loss conduction during fault-free conditions and rapidly establishing sufficient insulation levels during faults. Traditional mechanical switches are bulky, have long breaking times (tens of milliseconds), and complex structures, making them unsuitable for hybrid circuit breakers deployed in medium-voltage DC systems on aircraft. Therefore, developing a mechanical switch that offers fast breaking, simple structure, reliable operation, small size, and light weight is of great significance. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a mechanical switch with short switching time, simple structure, and good environmental adaptability.

[0005] To achieve the above objectives, the technical solution provided by this invention is: a rapid mechanical switch using an ultrasonic motor-driven flexible bistable mechanism, comprising: an ultrasonic motor and a flexible bistable mechanism, wherein the flexible bistable mechanism is connected to an active slider via an active component platform; the ultrasonic motor drives the active slider to reciprocate linearly via a friction strip, thereby causing the moving contact and disengagement of the moving contact and stationary contact of the flexible bistable mechanism; wherein the flexible bistable mechanism comprises four bistable beams arranged symmetrically in pairs, each bistable beam consisting of two flexible beams and one rigid element, and the beam constraint model is as follows:

[0006] Static modeling of the first flexible beam:

[0007]

[0008]

[0009] Where, k (l) mn (1) (l=0,1,2;m=1,2;n=1,2) and g (l) mn(1) (l=0,1,2;m=1,2;n=1,2) are the characteristic parameters of the first flexible beam. f1 is the normalized result of the tangential force F1 at the end of the first flexible beam; m1 is the normalized result of the torque M1 at the end of the first flexible beam; p1 is the normalized result of the axial force P1 at the end of the first flexible beam; t1 is the normalized result of the thickness T1 of the first flexible beam; δx1 is the displacement Δ in the X1 direction at the end of the first flexible beam. x1 The normalized result; δy1 is the Y1 direction Δ at the end of the first flexible beam. y1 The normalized result; α1 is the rotation angle at the end of the first flexible beam. The specific expression is:

[0010]

[0011] Where E1, I1, and L1 are the elastic modulus, moment of inertia, and length of the material used in the first flexible beam, respectively.

[0012] Similarly, the second flexible beam is modeled statically:

[0013]

[0014] Where, k (l) mn (2) (l=0,1,2;m=1,2;n=1,2) and g (l) mn (2) (l=0,1,2;m=1,2;n=1,2) are the characteristic parameters of the second flexible beam. f2 is the normalized result of the tangential force F2 at the end of the second flexible beam; m2 is the normalized result of the torque M2 at the end of the second flexible beam; p2 is the normalized result of the axial force P2 at the end of the second flexible beam; t2 is the normalized result of the thickness T2 of the second flexible beam; δx2 is the displacement Δ in the X2 direction at the end of the second flexible beam. x2 The normalized result; δy1 is the Y2 direction Δ at the end of the second flexible beam. y2 The normalized result; α2 is the rotation angle at the end of the second flexible beam. The specific expression is:

[0015]

[0016] Where E2, I2, and L2 are the elastic modulus, moment of inertia, and length of the material used for the second flexible beam, respectively.

[0017] For the rigid element, force analysis yields:

[0018] P'1cosθ1-F'1sinθ1+P'2cos(θ2+Π)-F'2sin(θ2+Π)=0

[0019] P'1sinθ1+F'1cosθ1+P'2sin(θ2+Π)+F'2cos(θ2+Π)=0

[0020] -M'1-M'2+P'1sin(θ3-θ1+α)-F'1cos(θ3-θ1+α)=0

[0021] Where P'1 and P'2 represent the axial forces on the rigid segment, F'1 and F'2 represent the tangential forces on the rigid segment, M'1 and M'2 represent the moments on the rigid segment, θ1 represents the tilt angle of the first flexible beam relative to the X-axis of the global coordinate system XO1Y when it is not deformed, θ2 represents the tilt angle of the second flexible beam relative to the X-axis of the global coordinate system XO1Y when it is not deformed, θ3 represents the tilt angle of the rigid segment relative to the X-axis of the global coordinate system XO1Y when it is not rotated, and α represents the rotation angle of the rigid segment;

[0022] Meanwhile, the forces and moments at the ends of the aforementioned flexible beams satisfy the same conditions as those on the rigid elements:

[0023] F1 = -F'1

[0024] P1 = -P'1

[0025] M1 = -M'1

[0026] F2 = -F'2

[0027] P2 = -P'2

[0028] M2 = -M'2

[0029] Combining geometric equations:

[0030]

[0031] Where, Δ d For the displacement of the flexible bistable mechanism, L x L y These represent the span and height of a flexible bistable beam, respectively.

[0032] Stress analysis of the second flexible beam yields the following results:

[0033] F=P2sin(θ2+π)+F2cos(θ2+π)

[0034] F d =4F

[0035] Combining the above equations, we can obtain the external force F. d and displacement Δ d The relationship.

[0036] Optionally, the flexible bistable mechanism is connected to the moving contact via bolts and nuts, and the stationary contact is embedded from the side of the stationary contact base and fixed by bolts and nuts passing through the holes of both the stationary contact and the stationary contact.

[0037] Optionally, the stationary contact base and the housing with countersunk holes on the upper and lower sides are connected to the switch base by screws.

[0038] Optionally, a ceramic plate is installed on the ultrasonic motor. When the ceramic plate receives a sinusoidal voltage with a phase difference of 90° sent by the mechanical switch controller, it is excited to generate axial vibration, thereby exciting the symmetrical and antisymmetrical modes of driving the ultrasonic motor. The superposition of the two modes causes the driving foot of the ultrasonic motor to perform elliptical motion.

[0039] Optionally, the elliptical motion of the driving foot is transmitted to the active slider through the contact friction force with the friction strip, causing the active slider to drive the flexible bistable mechanism to move away from the stationary contact, thereby separating the moving contact connected to the flexible bistable mechanism from the stationary contact.

[0040] Optionally, the active component platform is mounted on the active slider by screws.

[0041] Optionally, the active component platform is fixed to a flexible bistable mechanism by screws.

[0042] Optionally, the friction strip is fixed to one side of the active component platform by epoxy resin adhesive.

[0043] The advantages of this invention over existing technologies are as follows: This mechanical switch uses an ultrasonic motor to drive an active slider in reciprocating linear motion via a friction strip, causing the moving contact and stationary contact of the flexible bistable mechanism to come into contact and disengage. The ultrasonic motor has advantages such as fast response speed, large thrust, and good environmental adaptability, while the flexible bistable mechanism can spontaneously generate displacement after a finite input displacement without further input; the rapid and continuous force output of the ultrasonic motor enables the flexible bistable mechanism to generate a larger displacement in a short time. Attached Figure Description

[0044] Figure 1 This is an overall schematic diagram of a rapid mechanical switch for an ultrasonic motor-driven flexible bistable mechanism provided in an embodiment of the present invention;

[0045] Figure 2 An exploded view of an assembly of a fast mechanical switch using an ultrasonic motor-driven flexible bistable mechanism, according to an embodiment of the present invention.

[0046] Figure 3 This is a structural diagram of a flexible bistable mechanism provided in an embodiment of the present invention;

[0047] Figure 4A force analysis diagram of a flexible bistable mechanism provided in an embodiment of the present invention;

[0048] Figure 5 This is a force-displacement image of a flexible bistable mechanism provided in an embodiment of the present invention;

[0049] In the figure, 1-ultrasonic motor; 2-limiting mechanism; 3-active slider; 4-active component platform; 5-flexible bistable mechanism; 6-guide rail; 7-moving contact; 8-stationary contact; 9-stationary contact base; 10-switch base; 11-shell; 12-friction strip; 13-first ceramic plate; 14-second ceramic plate. Detailed Implementation

[0050] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to specific embodiments.

[0051] Reference Figure 1 and Figure 2 This embodiment provides a fast mechanical switch with an ultrasonic motor driven flexible bistable mechanism, including an ultrasonic motor 1, a limiting mechanism 2, an active slider 3, an active component platform 4, a flexible bistable mechanism 5, a guide rail 6, a moving contact 7, a stationary contact 8, a stationary contact base 9, a switch base 10, a housing 11, a friction strip 12, a first ceramic plate 13, and a second ceramic plate 14.

[0052] Specifically, the ultrasonic motor 1 serves as the driving source. Through the contact friction between the driving foot of the ultrasonic motor 1 and the friction strip 12, the active slider 3 and the active component platform 4 on it are driven to reciprocate linearly along the guide rail 6, thereby driving the flexible bistable mechanism 5 and the moving contact 7 connected to the flexible bistable mechanism 5 to contact and separate from the stationary contact 8.

[0053] Furthermore, the stationary contact base 9 with ribs on the rear side and the housing 12 with countersunk holes on the upper and lower sides are both connected to the switch base 10 by screws. The moving contact 7 is connected to the flexible bistable mechanism 5 by bolts and nuts. The stationary contact 8 is embedded from the side of the stationary contact base 9 and is fixed by bolts and nuts passing through the holes of both the stationary contact 8 and the stationary contact 9. At the same time, the portion of the stationary contact 8 extending to both sides passes through the square holes on the side of the housing 12 for further fixation. The driving component platform 4 is mounted on the upper side of the driving slider 3 by screws. The upper side of the driving component platform 4 is fixed to the portion of the flexible bistable mechanism 5 extending to the upper side of the driving component platform 4 by screws. A friction strip 12 is connected to the left side of the driving component platform 4 by epoxy resin adhesive.

[0054] for Figure 1The device shown connects the stationary contact 8 to a medium-voltage DC system. When a fault occurs in the medium-voltage DC system, an action signal is sent to the mechanical switch controller. The mechanical switch controller sends a sinusoidal voltage with a 90° phase difference to the first ceramic plate 13 and the second ceramic plate 14, exciting them to vibrate axially. The axial vibration of the first ceramic plate 13 and the second ceramic plate 14 excites two modes of driving the ultrasonic motor 1: symmetrical and antisymmetrical. The superposition of the two modes causes the driving foot of the ultrasonic motor 1 to perform elliptical motion. The elliptical motion of the driving foot is transmitted to the active slider 3 through the contact friction force with the friction strip 12, causing the active slider 3 to drive the flexible bistable mechanism 5 to move away from the stationary contact 8, thereby separating the moving contact 7 connected to the flexible bistable mechanism 5 from the stationary contact 8. After the medium-voltage DC system fault is cleared, the mechanical switch controller sends a sinusoidal voltage with a -90° phase difference to the first ceramic plate 13 and the second ceramic plate 14, and the stationary contact 8 and the moving contact 9 close again.

[0055] In this embodiment, as Figure 3 As shown, the flexible bistable mechanism 5 comprises four bistable beams arranged symmetrically in pairs. Each bistable beam consists of two flexible beams and one rigid element. Due to the symmetry of the bistable beams, a single bistable beam can be analyzed individually, and its force analysis is as follows: Figure 4 As shown.

[0056] The beam constraint model of the flexible bistable mechanism is as follows:

[0057] Static modeling of the first flexible beam:

[0058]

[0059] Where, k (l) mn (1) (l=0,1,2;m=1,2;n=1,2) and g (l) mn (1) (l=0,1,2;m=1,2;n=1,2) are the characteristic parameters of the first flexible beam. f1 is the normalized result of the tangential force F1 at the end of the first flexible beam; m1 is the normalized result of the torque M1 at the end of the first flexible beam; p1 is the normalized result of the axial force P1 at the end of the first flexible beam; t1 is the normalized result of the thickness T1 of the first flexible beam; δx1 is the displacement Δ in the X1 direction at the end of the first flexible beam. x1 The normalized result; δy1 is the Y1 direction Δ at the end of the first flexible beam. y1 The normalized result; α1 is the rotation angle at the end of the first flexible beam. The specific expression is:

[0060]

[0061] Where E1, I1, and L1 are the elastic modulus, moment of inertia, and length of the material used in the first flexible beam, respectively.

[0062] Similarly, the second flexible beam is modeled statically:

[0063]

[0064] Where, k (l) mn (2) (l=0,1,2;m=1,2;n=1,2) and g (l) mn (2) (l=0,1,2;m=1,2;n=1,2) are the characteristic parameters of the second flexible beam. f2 is the normalized result of the tangential force F2 at the end of the second flexible beam; m2 is the normalized result of the torque M2 at the end of the second flexible beam; p2 is the normalized result of the axial force P2 at the end of the second flexible beam; t2 is the normalized result of the thickness T2 of the second flexible beam; δx2 is the displacement Δ in the X2 direction at the end of the second flexible beam. x2 The normalized result; δy1 is the Y2 direction Δ at the end of the second flexible beam. y2 The normalized result; α2 is the rotation angle at the end of the second flexible beam. The specific expression is:

[0065]

[0066] Where E2, I2, and L2 are the elastic modulus, moment of inertia, and length of the material used for the second flexible beam, respectively.

[0067] For the rigid element, force analysis yields:

[0068] P'1cosθ1-F'1sinθ1+P'2cos(θ2+Π)-F'2sin(θ2+Π)=0

[0069] P'1sinθ1+F'1cosθ1+P'2sin(θ2+Π)+F'2cos(θ2+Π)=0

[0070] -M'1-M'2+P'1sin(θ3-θ1+α)-F'1cos(θ3-θ1+α)=0

[0071] Where P'1 and P'2 represent the axial forces on the rigid segment, F'1 and F'2 represent the tangential forces on the rigid segment, M'1 and M'2 represent the moments on the rigid segment, θ1 represents the tilt angle of the first flexible beam relative to the X-axis of the global coordinate system XO1Y when it is not deformed, θ2 represents the tilt angle of the second flexible beam relative to the X-axis of the global coordinate system XO1Y when it is not deformed, θ3 represents the tilt angle of the rigid segment relative to the X-axis of the global coordinate system XO1Y when it is not rotated, and α represents the rotation angle of the rigid segment;

[0072] Meanwhile, the forces and moments at the ends of the aforementioned flexible beams satisfy the same conditions as those on the rigid elements:

[0073] F1 = -F'1

[0074] P1 = -P'1

[0075] M1 = -M'1

[0076] F2 = -F'2

[0077] P2 = -P'2

[0078] M2 = -M'2

[0079] Combining geometric equations:

[0080]

[0081] Where, Δ d For the displacement of the flexible bistable mechanism, L x L y These represent the span and height of a flexible bistable beam, respectively.

[0082] Stress analysis of the second flexible beam yields the following results:

[0083] F=P2sin(θ2+π)+F2cos(θ2+π)

[0084] F d =4F

[0085] Combining the above equations, we can obtain the external force F. d and displacement Δ d The relationship.

[0086] The force-displacement relationship of the flexible bistable mechanism 5 is as follows: Figure 5 As shown. Combined with Figure 1The relationship between the fixed flexible bistable mechanism 5 and the fixed active platform 4, and the fixed active slider 3, indicates that when the ultrasonic motor 1 drives the active slider 3, active platform 4, flexible bistable mechanism 5, and moving contact 7 to produce a displacement pointing towards the stationary contact 8 through contact friction with friction strip 12, the input force required by the ultrasonic motor 1 is initially positive and then negative. That is, after reaching a certain displacement, the input force of the ultrasonic motor 1 and the flexible bistable mechanism 5 will simultaneously generate a force pointing towards the stationary contact 8, causing the moving contact 7 to move with a large acceleration. The force-displacement curve of the flexible bistable mechanism 5 describes the specific situation as follows: Under static equilibrium conditions, before the displacement of the flexible bistable mechanism 5 reaches x1, the larger the displacement, the greater the force required. When the displacement reaches x1, the required force reaches its maximum, which is called the first steady-state critical force. After the displacement of the flexible bistable mechanism 5 reaches x1, the force required to produce a larger displacement decreases until it drops to 0. When the displacement of the flexible bistable mechanism 5 continues to increase, the required input force becomes negative in order to satisfy the static equilibrium condition. That is, if the input force is removed, the flexible bistable mechanism 5 will automatically generate displacement until the required input force is positive again.

[0087] The aforementioned characteristics, combined with the advantages of the ultrasonic motor 1's fast response and large output force, enable a shorter contact and separation time between the moving contact 7 and the stationary contact 8.

[0088] As described above, the rapid mechanical switch provided in this embodiment, driven by the ultrasonic motor 1 via the friction strip 12, reciprocates linearly with the active slider 3, causing the moving contact 7 of the flexible bistable mechanism 5 to contact and disengage from the stationary contact 8. The flexible bistable mechanism 5 has the advantages of simple structure and light weight. Furthermore, after a certain displacement is input into the initial position (first stable state) of the flexible bistable mechanism 5, it will exhibit characteristics similar to negative stiffness within a certain range, meaning it can automatically reach the second stable state without further displacement input. These characteristics, combined with the rapid response and high thrust-to-weight ratio of the ultrasonic motor, enable a shorter operating time and lighter weight for the mechanical switch. The limiting mechanism 2 is used to limit the distance by which the active slider 3 separates the moving contact 7 from the stationary contact 8, preventing damage to the flexible bistable mechanism 5. This invention has a simple structure, rapid operation, and is suitable for environments with electromagnetic interference and weight sensitivity, and can be applied to fault current interruption in medium-voltage DC circuits.

[0089] The above description is merely a specific implementation measure of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations, substitutions, or heterogeneities that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A rapid mechanical switch using an ultrasonic motor-driven flexible bistable mechanism, characterized in that, include: An ultrasonic motor and a flexible bistable mechanism are used. The flexible bistable mechanism is connected to the active slider via an active component platform. The ultrasonic motor drives the active slider to reciprocate linearly via a friction strip, causing the moving and stationary contacts of the flexible bistable mechanism to contact and disengage. The flexible bistable mechanism comprises four bistable beams arranged symmetrically in pairs. Each bistable beam consists of two flexible beams and one rigid element. The beam constraint model is as follows: Static modeling of the first flexible beam: Where, k (l) mn (1) (l=0,1,2;m=1,2;n=1,2) and g (l) mn (1) (l=0,1,2;m=1,2;n=1,2) are the characteristic parameters of the first flexible beam. f1 is the normalized result of the tangential force F1 at the end of the first flexible beam; m1 is the normalized result of the torque M1 at the end of the first flexible beam; p1 is the normalized result of the axial force P1 at the end of the first flexible beam; t1 is the normalized result of the thickness T1 of the first flexible beam; δx1 is the displacement Δ in the X1 direction at the end of the first flexible beam. x1 The normalized result; δy1 is the Y1 direction Δ at the end of the first flexible beam. y1 The normalized result; α1 is the rotation angle at the end of the first flexible beam. The specific expression is: Where E1, I1, and L1 are the elastic modulus, moment of inertia, and length of the material used in the first flexible beam, respectively. Similarly, the second flexible beam is modeled statically: Where, k (l) mn (2) (l=0,1,2;m=1,2;n=1,2) and g (l) mn (2) (l=0,1,2;m=1,2;n=1,2) are the characteristic parameters of the second flexible beam. f2 is the normalized result of the tangential force F2 at the end of the second flexible beam; m2 is the normalized result of the torque M2 at the end of the second flexible beam; p2 is the normalized result of the axial force P2 at the end of the second flexible beam; t2 is the normalized result of the thickness T2 of the second flexible beam; δx2 is the displacement Δ in the X2 direction at the end of the second flexible beam. x2 The normalized result; δy1 is the Y2 direction Δ at the end of the second flexible beam. y2 The normalized result; α2 is the rotation angle at the end of the second flexible beam. The specific expression is: Where E2, I2, and L2 are the elastic modulus, moment of inertia, and length of the material used for the second flexible beam, respectively. For the rigid element, force analysis yields: P'1cosθ1-F'1sinθ1+P'2cos(θ2+Π)-F'2sin(θ2+Π)=0 P'1sinθ1+F'1cosθ1+P'2sin(θ2+Π)+F'2cos(θ2+Π)=0 -M'1-M'2+P'1sin(θ3-θ1+α)-F'1cos(θ3-θ1+α)=0 Where P,1 and P,2 represent the axial forces on the rigid segment, F,1 and F,2 represent the tangential forces on the rigid segment, M,1 and M,2 represent the moments on the rigid segment, θ1 represents the tilt angle of the first flexible beam relative to the X-axis of the global coordinate system XO1Y when it is not deformed, θ2 represents the tilt angle of the second flexible beam relative to the X-axis of the global coordinate system XO1Y when it is not deformed, θ3 represents the tilt angle of the rigid segment relative to the X-axis of the global coordinate system XO1Y when it is not rotated, and α represents the rotation angle of the rigid segment. Meanwhile, the forces and moments at the ends of the aforementioned flexible beams satisfy the same conditions as those on the rigid elements: F1 = -F'1 P1 = -P'1 M1 = -M'1 F2 = -F'2 P2 = -P'2 M2 = -M'2 Combining geometric equations: Where, Δ d For the displacement of the flexible bistable mechanism, L x L y These represent the span and height of a flexible bistable beam, respectively. Stress analysis of the second flexible beam yields the following results: F=P2sin(θ2+π)+F2cos(θ2+π) F d =4F Combining the above equations, we can obtain the external force F. d and displacement Δ d The relationship.

2. The fast mechanical switch according to claim 1, characterized in that: The flexible bistable mechanism is connected to the moving contact via bolts and nuts. The stationary contact is embedded from the side of the stationary contact base and is fixed by bolts and nuts passing through the holes of both the stationary contact and the stationary contact.

3. The fast mechanical switch according to claim 2, characterized in that: The stationary contact base and the outer casing with countersunk holes on the upper and lower sides are connected to the switch base by screws.

4. The fast mechanical switch according to claim 1, characterized in that: The ultrasonic motor is equipped with a ceramic plate. When the ceramic plate receives a sinusoidal voltage with a phase difference of 90° sent by the mechanical switch controller, it is excited to generate axial vibration, thereby exciting the ultrasonic motor to drive two modes, symmetric and antisymmetric. The superposition of the two modes causes the ultrasonic motor to drive the foot to perform elliptical motion.

5. The fast mechanical switch according to claim 4, characterized in that: The elliptical motion of the driving foot is transmitted to the active slider through the contact friction force with the friction strip, causing the active slider to drive the flexible bistable mechanism to move away from the stationary contact, thereby separating the moving contact connected to the flexible bistable mechanism from the stationary contact.

6. The fast mechanical switch according to claim 1, characterized in that: The active component platform is mounted on the active slider by screws.

7. The fast mechanical switch according to claim 1, characterized in that: The active component platform is fixed to a flexible bistable mechanism by screws.

8. The fast mechanical switch according to claim 1, characterized in that: The friction strip is fixed to one side of the active component platform by epoxy resin adhesive.

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