Collision interception type laminated fuze MEMS recoil safety mechanism with vertical elastic shaft arrangement

Abstract

The invention discloses a collision interception type laminated MEMS recoil safety mechanism arranged perpendicular to an elastic shaft, and belongs to the technical field of fuse safety and safety release. The mechanism sequentially comprises a top plate, an upper mass block layer, a middle layer, a lower mass block layer and a bottom plate from top to bottom, wherein the upper mass block layer and the lower mass block layer are respectively provided with an upper mass block and a lower mass block which are connected through a micro spring, the middle layer is provided with a channel for the upper mass block to pass through, and a rebound interval is reserved between the bottom plate and the lower mass block. According to the invention, insurance logic is realized by using different dynamic responses of the double mass blocks under a load: under a short pulse width drop load, the lower mass block touches the bottom and rebounds, and collides with the upper mass block which moves downwards, so that the upper mass block cannot reach the de-insurance displacement; under the long-pulse-width emission load, the lower mass block is pressed at the bottom due to continuous overload, and a movement channel is reserved for the upper mass block, so that the upper mass block moves downwards to complete de-insurance. The device is compact in structure, and is suitable for a vertical elastic shaft type MEMS (Micro Electro Mechanical System) installation device.

Description

Technical Field

[0001] This invention belongs to the field of fuse safety and deactivation technology, specifically relating to a MEMS (Micro-Electro-Mechanical Systems) recoil safety mechanism that is arranged vertically on the spring axis and uses the principle of dual-mass block collision interception to distinguish between service drop and launch payload. Background Technology

[0002] In the design of fuse release mechanisms, the primary function of the recoil safety mechanism is to sense the recoil overload during firing to release the safety, while simultaneously ensuring safety under accidental drop impacts during service phases (such as transportation and loading / unloading). Drop impact loads are typically characterized by high amplitude and short duration (short pulse width); while launch loads are typically characterized by moderate amplitude and long duration (long pulse width). Specifically, the launch load of small-caliber projectiles is typically 30,000g to 110,000g, with a pulse width of 3ms to 7ms; the launch load of medium and large-caliber projectiles is typically 1,000g to 30,000g, with a launch pulse width of 1.4ms to 8ms; and the service load is typically 5,000g to 20,000g, with a pulse width of 0.1ms to 0.3ms.

[0003] Existing MEMS recoil safety mechanisms employ either a parallel or perpendicular arrangement to the projectile axis. For small-caliber projectiles, the high impact load during firing allows a single-degree-of-freedom cantilever beam recoil safety mechanism with a perpendicular projectile axis to distinguish between service and firing loads, meeting the requirements for service safety and reliable deactivation. However, medium- and large-caliber projectiles experience relatively low firing loads. A single-degree-of-freedom cantilever beam recoil safety mechanism struggles to effectively distinguish between drop interference and firing loads based solely on amplitude differences, leading to potential malfunctions under drop conditions and compromising safety and reliability throughout the projectile's lifespan. Therefore, medium- and large-caliber projectiles have opted for recoil safety mechanisms such as Z-tooth, zigzag grooves, gating mechanisms, and dual-degree-of-freedom systems. However, because these recoil safety mechanisms are planar structures, they sense recoil loads in the direction parallel to the projectile axis, necessitating a parallel projectile axis arrangement. This increases the axial dimension and requires corners for detonation transmission, resulting in insufficient detonation transmission reliability. Therefore, a MEMS recoil safety mechanism with a perpendicular projectile axis arrangement and the ability to differentiate between these loads is urgently needed. Summary of the Invention

[0004] The purpose of this invention is to provide a MEMS recoil safety mechanism with a vertically arranged projectile axis. By utilizing the different dynamic responses of the two mass blocks under different pulse width loads, the lower mass block collides with the upper mass block after bottoming out and rebounding, thus intercepting the upper mass block. This achieves the distinction between launch load and drop load, solves the problem of insufficient safety of existing mechanisms in drop environments, and fills the gap in MEMS recoil safety mechanisms with a vertically arranged projectile axis suitable for medium and large caliber projectiles.

[0005] The technical solution to achieve the purpose of this invention is as follows:

[0006] A collision interception type stacked fuse MEMS recoil safety mechanism with a vertical spring axis arrangement is composed of a top plate, an upper mass block layer, an intermediate layer, a lower mass block layer and a bottom plate stacked in sequence.

[0007] The upper mass block layer includes an upper mass block layer frame and an upper spring mass block system suspended and fixed at the center of the upper mass block layer frame;

[0008] The intermediate layer is used to provide a motion space for the upper spring-mass system and the lower spring-mass system parallel to a single axis.

[0009] The lower mass block layer includes a lower mass block layer frame and a lower spring mass block system suspended and fixed at the center of the lower mass block layer frame;

[0010] The base plate is used to limit the entire mechanism and has space to limit the maximum travel of the lower spring mass block system.

[0011] The upper and lower spring mass systems are made of the same material and are coaxially aligned in the direction parallel to the spring axis. The upper spring mass system has a smaller mass than the lower spring mass system, the natural frequency of the lower spring mass system should be higher than that of the upper spring mass system, and the bottoming displacement of the lower spring mass system should be shorter than the displacement required for the upper spring mass system to reach the release position.

[0012] The significant advantages of this invention compared to existing technologies are:

[0013] (1) Unlike the parallel projectile axis design of traditional MEMS recoil safety mechanism, the present invention adopts a stacked design with a vertical projectile axis, which makes full use of the axial space of the projectile, significantly reduces the axial height of the safety release device, improves the reliability of the detonation transmission, and is suitable for medium and large caliber projectiles.

[0014] (2) The insurance logic is designed with the idea of ​​"collision interception". Unlike traditional mechanisms that rely solely on increasing damping or stiffness to resist impact, this invention uses the rapid response of the lower mass block to form a physical barrier under short load impacts such as drops, while automatically giving way to the channel in long pulse transmission environments. This achieves the distinction between service and transmission environments, and significantly improves safety under drop conditions.

[0015] (2) The overall structure is easy to mass-produce using MEMS precision metal laser processing technology, resulting in low processing costs and high product consistency and yield. Attached Figure Description

[0016] Figure 1 This is a schematic diagram (and exploded view) of the overall structure of the recoil safety mechanism of the MEMS safety release device of the present invention.

[0017] Figure 2 This is a front view of the mechanism of the present invention.

[0018] Figure 3 This is a schematic diagram illustrating the motion principle of the present invention during the service drop phase (high amplitude, short pulse width).

[0019] Figure 4 This is a schematic diagram illustrating the motion principle of the present invention during the normal transmission phase (low amplitude, long pulse width).

[0020] Figure 5 The figures show the displacement-time simulation curves of the upper mass block under two working conditions in this embodiment of the invention.

[0021] Figure 6 The figures show the displacement-time simulation curves of the lower mass block under two working conditions in this embodiment of the invention. Detailed Implementation

[0022] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0023] like Figure 1 As shown, this embodiment provides a MEMS recoil safety mechanism with a vertical spring shaft arrangement. The overall structure consists of a top plate 1, an upper mass block layer, a middle layer 3, a lower mass block layer, and a bottom plate 5 stacked from top to bottom.

[0024] The upper mass block layer is located below the top plate 1 and mainly consists of an upper mass block layer frame 2, an upper mass block 6, and upper springs 7. The upper mass block 6 is suspended and fixed at the center of the upper mass block layer frame 2 by upper springs 7 evenly distributed on both the left and right sides, allowing it to move along the Z-axis direction, which is perpendicular to the plate surface and parallel to the spring axis direction. Figure 2 It can be seen that the thickness of the upper mass block 6 is d1.

[0025] The intermediate layer 3 is located between the upper mass block layer and the lower mass block layer, and has space provided for the downward movement of the upper mass block 6. The thickness of the intermediate layer 3 is set to d2.

[0026] The lower mass block layer is located below the intermediate layer 3 and mainly consists of a lower mass block layer frame 4, lower springs 8, and a lower mass block 9. The lower mass block 9 is suspended and fixed at the center of the lower mass block layer frame 4 by lower springs 8 evenly distributed on both the left and right sides. The upper mass block 6 is made of the same material as the lower mass block 9 and is coaxially aligned in the Z-axis direction. The projected area of ​​the upper mass block 6 along the spring axis is slightly smaller than the area of ​​the lower mass block 9. The thickness of the lower mass block 9 is d3.

[0027] The base plate 5 is located at the bottom layer and is used to limit the movement of the entire mechanism. In the initial state, the upper end of the base plate 5 has a slot, and a gap d4 is reserved between it and the lower surface of the lower mass block 9 (see...). Figure 2 The spacing d4 defines the maximum downward travel of the lower mass block 9.

[0028] In this embodiment, the unlocking criterion of the mechanism is set as follows: the downward displacement of the upper mass block 6 reaches d1+d2. That is, the upper mass block 6 needs to pass through the thickness area of ​​the middle layer 3 and completely enter the thickness range of the layer where the lower mass block 9 is located before the subsequent unlocking action (such as unlocking the explosion-proof slider) can be triggered.

[0029] A dynamic mathematical model of the mechanism is established based on classical mechanics. The upper mass block 6 and the lower mass block 9 are regarded as a spring-mass-damping system. z1 and z2 are defined as the displacements of the upper mass block 6 and the lower mass block 9 along the Z-axis, respectively, with the downward direction being positive.

[0030] The system's set of differential equations of motion is shown below:

[0031]

[0032] In the formula, Let X be the acceleration, velocity, and displacement of the upper mass block relative to the base plate. Let m1 be the acceleration, velocity, and displacement of the lower mass block relative to the base plate, and m2 be the masses of the upper mass block 6 and the lower mass block 9, respectively; c1 and c2 are the damping coefficients of the spring-mass system, and in this embodiment, the damping ratio is taken as... , , k1 and k2 are the overall equivalent stiffness of the upper and lower springs, respectively; g(t) is the externally input acceleration load function.

[0033] In this embodiment, the external input load function g(t) is simulated as a half-sine wave pulse signal, and its mathematical expression is:

[0034]

[0035] In the formula, A is the peak acceleration of the pulse, T is the pulse duration (pulse width), t is the time history of the impact load, and t=0 is defined as the instant when the external pulse load g(t) begins to act.

[0036] The core of this invention lies in the collision interception mechanism. When the upper mass block 6 catches up with the lower mass block 9, or when the lower mass block 9 rebounds upwards and meets the upper mass block 6 (i.e., the geometric contact condition is met), the two mass blocks undergo a non-perfectly elastic collision. According to the law of conservation of momentum and the definition of the coefficient of restitution, the instantaneous velocity of the upper mass block 6 and the lower mass block 9 after the collision... and The calculation is as follows:

[0037]

[0038] In the formula, , The instantaneous velocities of the upper mass block 6 and the lower mass block 9 before their collision are respectively; e 12 The collision recovery coefficient between the two masses is set to 0.7 in this embodiment. This formula reflects the physical process under drop conditions where the rebounding lower mass 9 forces the upper mass 6 to decelerate or move in the opposite direction through momentum exchange. Let z2 = d4, solve for the bottoming time, substitute the bottoming time into the velocity function, and the calculated instantaneous velocity is the incident velocity.

[0039] Furthermore, when the current mass block 9 moves downward to its extreme position (displacement reaches d4) and collides with the base plate 5, its rebound speed... Determined by the following formula:

[0040]

[0041] In the formula, e1 represents the incident velocity of the lower mass block 9 before it hits the bottom, and e2 represents the collision recovery coefficient between the lower mass block and the base plate, which is set to 0.7 in this embodiment. This boundary condition determines the rebound capability of the lower mass block under short-pulse drop loads.

[0042] The stiffness-to-mass ratio (k1 / m1 and k2 / m2) of the two mass blocks determines their phase difference in the time domain response, while parameters (d1 to d4) define the collision boundary of the system. The natural frequency of the lower mass block should be higher than that of the upper mass block, and the bottoming displacement of the lower mass block should be shorter than the displacement required for the upper mass block to reach the release position. This allows for spatial interception using the phase difference in the time domain response. By solving this model, the transient displacement response under different load conditions can be obtained, yielding the minimum release threshold curve. The structural parameters can then be adjusted based on the minimum threshold curve and the load requirements.

[0043] In this embodiment, the geometric parameters of each layer are designed as follows (see Figure 2 The thickness of the upper mass block is d1 = 200 μm, the thickness of the middle layer is d2 = 200 μm, the thickness of the lower mass block is d3 = 200 μm, and the distance between the lower mass block and the base plate is d4 = 250 μm. Therefore, the theoretical solution-preserving displacement of the system is 400 μm (i.e., d1 + d2).

[0044] This invention utilizes the difference in dynamic response of two mass blocks under different pulse width loads and the collision mechanism to achieve the insurance function.

[0045] (1) Combining duty drop phase Figure 3 (Illustration of the principle of duty fall) Figure 5 and Figure 6The simulation curve (18000g / 0.1ms condition) illustrates the following: When encountering an unexpected drop during the service phase, the external load exhibits characteristics of high amplitude (e.g., 18000g) and short pulse width (e.g., 0.1ms). (Reference) Figure 6 The "lower mass displacement" curve shows that lower mass 9 responded rapidly, reaching a displacement of 250 μm (d4) at approximately 0.8 × 10e-4 s, and colliding with the base plate 5. Due to the extremely short pulse width, the external overload had already begun to decay at the time of the collision. After colliding with the base plate 5, lower mass 9 rebounded rapidly, and the displacement curve showed a distinct "V"-shaped rebound, rebounding to a height of approximately 170 μm at around 1.5 × 10e-4 s. Meanwhile, reference... Figure 5 The "upper mass block displacement" curve shows that upper mass block 6 moves downwards due to inertia. When the rebounding lower mass block 9 meets the downward-moving upper mass block 6 in the intermediate layer 3 region, a collision occurs. The kinetic energy of upper mass block 6 is dissipated in the collision, and its maximum downward displacement is approximately 368 μm. Since 368 μm < 400 μm (the release threshold), upper mass block 6 fails to reach the release displacement.

[0046] (2) Normal launch phase combined Figure 4 (Schematic diagram of normal launch principle) Figure 5 and Figure 6 The simulation curves (3000g / 6ms condition) illustrate the following: When the projectile is fired, the external load exhibits characteristics of low amplitude (e.g., 3000g) and long pulse width (e.g., 6ms). (Reference) Figure 6 The "lower mass displacement" curve shows that lower mass 9 bottoms out at approximately 1 × 10e-3 s (displacement 250 μm). Due to the long duration of the external overload (6 ms), lower mass 9 is "pressed" onto the base plate 5 by the continuous overload force, without significant rebound, thus allowing the upper mass 6 to move downwards. (Reference) Figure 5 The "upper mass block displacement" curve shows that the upper mass block 6 accelerated downwards under continuous overload and successfully passed through the intermediate layer 3. Within a time period of approximately 2.5 × 10e-3 s to 3.7 × 10e-3 s, the peak displacement of the upper mass block 6 reached approximately 440 μm. Since 440 μm > 400 μm (the release threshold), the upper mass block 6 successfully reached the release displacement, triggering subsequent release actions.

[0047] In summary, this embodiment, through a five-layer structural layout and spacing design, utilizes the rebound characteristics of the lower mass block under short pulses to implement "collision interception," which can effectively solve the problem of insufficient safety of MEMS security devices in drop environments.

[0048] It should be noted that one of the core innovations of this invention lies in using the "rapid rebound of the lower structure" to intercept the "downward movement of the upper structure," thereby achieving differentiation of loads with different pulse widths. Therefore, the scope of protection of this invention is not limited to the five-layer structure of "single-layer upper mass block + single-layer lower mass block" shown in the above embodiments.

[0049] Those skilled in the art should understand that, in order to adapt to the inherent frequencies of different ammunition spaces or regulation systems, both the upper mass block layer (defense execution end) and the lower mass block layer (interception end) can adopt a "multi-layered" or "arrayed" design. For example:

[0050] Regarding the extension of the release and protection execution end: the upper mass block 6 can be composed of two or more layers of mass blocks connected in series or in parallel in the Z-axis direction, with each layer separated by an intermediate layer or directly connected. In this case, these multiple layers of mass blocks together constitute the "release and protection execution component" described in this invention.

[0051] Regarding the expansion of the interception end: the lower mass block 9 can also consist of two or more layers of mass blocks (e.g., designed as a stacked structure with three, four, or even more mass blocks). By setting up multiple levels of lower mass blocks and utilizing multi-level collision to transfer momentum, the interception timing can be further delayed to adapt to different impact loads. In this case, these multiple layers of mass blocks together constitute the "interception component" described in this invention.

[0052] Any technical solution that uses at least one inertial component to generate a rebound motion and physically blocks or interferes with another inertial component along the motion path to distinguish between a drop and a launch load is a technical concept of this invention and falls within the protection scope of this invention.

Claims

1. A collision-interception type stacked fuze MEMS recoil safety mechanism with a vertically arranged spring shaft, characterized in that, It consists of a top plate, an upper mass block layer, an intermediate layer, a lower mass block layer, and a bottom plate stacked in sequence. The upper mass block layer includes an upper mass block layer frame and an upper spring mass block system suspended and fixed at the center of the upper mass block layer frame; The intermediate layer is used to provide a motion space for the upper spring-mass system and the lower spring-mass system parallel to a single axis. The lower mass block layer includes a lower mass block layer frame and a lower spring mass block system suspended and fixed at the center of the lower mass block layer frame; The base plate is used to limit the entire mechanism and has space to limit the maximum travel of the lower spring mass block system. The upper and lower spring mass systems are made of the same material and are coaxially aligned in the direction parallel to the spring axis. The upper spring mass system has a smaller mass than the lower spring mass system, the natural frequency of the lower spring mass system should be higher than that of the upper spring mass system, and the bottoming displacement of the lower spring mass system should be shorter than the displacement required for the upper spring mass system to reach the release position.

2. The collision interception type stacked fuze MEMS recoil safety mechanism with vertical spring axis arrangement according to claim 1, characterized in that, The upper spring mass block system includes an upper mass block and upper springs evenly distributed on the left and right sides of the upper mass block; the lower spring mass block system includes a lower mass block and lower springs evenly distributed on the left and right sides of the lower mass block; the projected area of ​​the upper mass block along the spring axis is slightly smaller than the area of ​​the lower mass block.

3. The collision interception type stacked fuze MEMS recoil safety mechanism with vertical spring axis arrangement according to claim 1, characterized in that, The thickness of the upper spring mass block system is d1, the thickness of the lower spring mass block system is d3, the distance between the lower mass block and the base plate is d4, and d4 < d1 + d2.

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