A low-cost explosion-proof delay fuse for a grenade

Abstract

The application discloses a low-cost explosion-proof delay fuse for a grenade, which comprises a body, a rotating shaft, a torsion spring, a safety pin, a fire isolation cup, an impact primer, a primer seat, a blunt flame delay detonator, a flap, a grip piece, a striker and a quick-release pin, and meets the requirement of explosion-proof safety. The striker is arranged in a straight line on the blunt flame delay detonator, and the impact primer is fixed on the flap in a spatially staggered and isolated state. The quick-release pin and the safety pin, which are manually released by different actions, serve as the redundant safety of the flap. Before throwing, the two safeties are manually released when the grip piece is gripped. After throwing, the grip piece falls off, the impact primer on the flap rotates around the rotating shaft under the action of the torsion spring, hits the striker and fires, high-temperature and high-pressure gas passes through the fire transmission hole on the striker, triggers the blunt flame delay detonator, and explodes the main charge in the grenade body after a predetermined delay. The application has a simple and compact structure, a short exposed grenade body and low cost.

Description

Technical Field

[0001] This invention pertains to fuze technology, specifically relating to a low-cost, explosion-proof time-delay fuze for hand grenades. Background Technology

[0002] Hand grenades and their fuses require manual operation; therefore, the safety design requirements for hand grenade fuses differ from the general "Fuse Safety Design Guidelines" (National Military Standard GJB373B-2019 and US Military Standard MIL-STD-1316F). Instead, they are governed by specific "Safety Design Guidelines for Manually Installed Weapons" (National Military Standard GJB3194-1998 and US Military Standard MIL-STD-1911). Aside from specific provisions regarding redundancy safety requirements, the two standards, namely the "Safety Design Guidelines for Manually Installed Weapons" and the "Fuse Safety Design Guidelines," are largely similar in content. However, according to the US military standards manual MIL-HDBK-145C, "Overview of Active Fuses," none of the 17 hand grenade fuse models listed meet the requirements of MIL-STD-1911, including the most basic explosion-proof safety requirements and redundancy safety requirements. In recent years, domestically produced products have been developed in accordance with the requirements of GJB3194-1998 "Safety Design Guidelines for Manually Deployed Weapons," which can meet the requirements for explosion-proof safety. However, some have failed to further meet the requirements for redundancy safety, and some have overly complex structures, making them inconvenient to operate and use, and also relatively expensive. In addition, the relatively long exposed part of the fuse makes it difficult to make the grenade uniform in shape, i.e., spherical or close to spherical. Therefore, when thrown from different directions (attitudes) or when the grenade flies in different attitudes in the air, the drag will be significantly different, resulting in a large dispersion of the impact point. It is difficult to meet the accuracy and precision requirements of the impact point when attacking or defending (see: Wang Yushi, Wu Boyong, Wen Quan, et al. Ballistic Characteristics Analysis of Handleless Grenade and Its Fuze Design. Journal of Projectiles, Rockets and Guidance, 2015, No. 5, pp. 57-60).

[0003] Chinese patent CN102466435A, "A Hand Grenade Fuze," the paper "Research on Electromechanical Hand Grenade Fuze" (Li Ning, Qi Xinglin, Cui Ping, et al., *Sichuan Ordnance Journal*, 2007, No. 5), the paper "Electronic Trigger Fuze for Hand Grenades Using Magnetoelectric Generators" (Sun Zhongsheng, Guo Junxian, Hao Yimin, et al., *Journal of Detection and Control*, 2010, No. 2), and the paper "Research and Design of Digital Hand Grenade Fuzes" (Zhou Ming'an, Guo Tiantian, Cheng Xiaodong, et al., *Sichuan Ordnance Journal*, 2014, No. 8) do not address the safety requirements (such as explosion-proof safety and redundant safety) and the specific technical structures for their implementation as stipulated in GJB3194-1998 *Safety Design Guidelines for Manually Deployed Weapons*. Chinese patents CN102278917A, "A Service Insurance Mechanism for a Hand Grenade Fuze," and CN102374831A, "An Insurance Mechanism for a Hand Grenade Fuze," only disclose the insurance mechanism for hand grenade fuses and do not involve the safety requirements stipulated in GJB3194-1998, "Safety Design Guidelines for Manually Deployed Weapons," such as explosion-proof safety and redundant insurance. Summary of the Invention

[0004] The purpose of this invention is to provide a simple, low-cost, and redundant safety delayed-action fuze for grenades. The exposed portion of the fuze is relatively short, which does not significantly affect the aerodynamic uniformity of the grenade, thereby helping to improve the throwing accuracy and precision during offensive and defensive operations.

[0005] The technical solution for achieving the purpose of this invention is a simple, low-cost, and redundantly safe grenade-type explosion-proof delayed fuse, comprising a body, an ignition and explosion-proof module, a safety module, and an insensitive flame delay detonator module. The structure and principle of the ignition and explosion-proof module and the safety module are basically the same as those of existing grenade-type delayed fuses (such as the American M201 series fuses), including a firing pin, a flap, a pivot, a torsion spring, a grip, a safety pin, and a safety ring. Therefore, the main actions before throwing, such as pulling out the safety pin and tightening the grip, remain unchanged, which helps users quickly and skillfully master the operation and usage requirements. The main difference is that the positions of the firing pin and the impact cap are interchanged spatially, thus increasing the explosion-proof function. The original sensitive impact delay detonator is replaced with an insensitive flame delay detonator, and an explosion-proof cup and a quick-release pin safety mechanism are added. The body needs to be adapted to the new structure, but the main structure is basically the same as that of existing grenade-type delayed fuses, and the height of the exposed part is shortened.

[0006] The main body is the primary structural component of the fuse, and it is threaded to connect with the projectile. With the axis of this thread as its axis of symmetry, the outer contour of the main body is essentially a body of revolution. Six through holes are provided along the axis from the top surface of the main body, numbered from top to bottom as the first, second, third, fourth, fifth, and sixth order holes. A first transverse hole is located on the main body, offset from the axis, near a position corresponding to half the depth of the first order hole, along the radial and axial perpendicular directions. A second transverse hole, parallel to the first transverse hole, is located on the main body, offset from the axis, outside the first transverse hole, near a position corresponding to half the depth of the third order hole. A third transverse hole, parallel to the first transverse hole, is located outside the first transverse hole and between the first and second transverse holes. A cantilever protrusion, parallel to the first transverse hole, is located on the outer edge of the main body on the opposite side symmetrical to the first transverse hole. The ignition and explosion-proof module is located within the first, third, and fourth order holes. The insensitive flame delay detonator is located within the sixth order hole, and a safety module is used to secure the ignition and explosion-proof module.

[0007] The first horizontal hole of the main body is used to install the shaft of the ignition and explosion-proof module, which is arranged around the first horizontal hole; the second horizontal hole of the main body is used to install the safety pin of the safety module of the ignition and explosion-proof module; the third horizontal hole is used to install the quick-release pin of the safety module of the ignition and explosion-proof module, which is mainly arranged around the second horizontal hole.

[0008] Compared to existing non-explosion-proof grenade delay fuses such as the American M201 series fuses, this is equivalent to dividing the original sensitive impact delay detonator into two parts used in series: the input end becomes a sensitive impact cap, and the delay and output ends are sealed and insensitive flame delay detonators; a quick-release pin is added to the upper end of the safety pin, which is a safety device that is manually released by pressing and pulling out; before throwing, the button at the end of the quick-release pin must be pressed to pull it out of the body and release this safety first; the so-called insensitive flame delay detonator means that the igniter, detonator, delay charge, and high explosive charge inside are all permissible in-line explosives with a sensitivity not higher than tertür.

[0009] Compared with the prior art, the significant advantages of the present invention are:

[0010] (1) It does not require changes to the existing fuse's external dimensions, mass, or interface dimensions with the warhead, and does not change the main operating procedures.

[0011] (2) Meet the relevant requirements of GJB3194-1998 "Safety Design Guidelines for Manually Deployed Weapons" regarding safety failure rate, explosion protection, in-line charge sensitivity, redundancy protection, ignition delay control, fault insurance design, human factors engineering, internal energy storage, compatibility, and fire insulation.

[0012] (3) The structure is compact and simple, the parts are easy to manufacture, and the cost is low.

[0013] (4) After the insensitive detonator shell is thickened, reinforced and coated with heat insulation material, it can meet the requirements of insensitivity and low vulnerability.

[0014] (5) The impact ignition principle is adopted, which can ensure the safety of handling unexploded ordnance and explosives. Attached Figure Description

[0015] Figure 1 This is a sectional view (front view) along the structural symmetry plane of a low-cost, explosion-proof time-delay fuse for hand grenades according to the present invention.

[0016] Figure 2 This is a top view of a low-cost, explosion-proof time-delay fuse for hand grenades according to the present invention.

[0017] Figure 3 This is a cross-sectional view (left view) of a low-cost, explosion-proof time-delay fuse for hand grenades according to the present invention, with the safety pin and safety ring aligned with the central axis and perpendicular to the plane of symmetry before assembly.

[0018] Figure 4 This is a projection diagram of a low-cost, explosion-proof time-delay fuse for hand grenades according to the present invention, along a direction perpendicular to the plane of symmetry.

[0019] Figure 5 This is a right view of a low-cost, explosion-proof time-delay fuze for hand grenades according to the present invention before assembly of the grip, safety pin, safety ring, and quick-release pin.

[0020] Figure 6 This is a BB cross-sectional view of a low-cost, explosion-proof time-delay fuze for hand grenades according to the present invention. The BB section is parallel to the fuze axis.

[0021] Figure 7 This is an isometric drawing of a low-cost, explosion-proof time-delay fuse safety pin for a hand grenade, as described in this invention.

[0022] 1 is the main body, 2 is the rotating shaft, 3 is the torsion spring, 4 is the safety pin, 5 is the impact cap, 6 is the cap holder, 7 is the desensitized flame delay detonator, 8 is the flap, 9 is the grip, 10 is the firing pin, 11 is the quick-release pin, 12 is the safety ring, 13 is the flame shield, 71 is the reinforcing cap, 72 is the desensitized high explosive, 73 is the first desensitized ignition charge, 74 is the desensitized delay charge, 75 is the barrier plate, 76 is the second desensitized ignition charge, and 77 is the casing.

[0023] The materials used in these components are all commonly used materials, and their compatibility meets the compatibility requirements of GJB3194-1998 "Safety Design Guidelines for Manually Deployed Weapons". Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0025] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0026] Furthermore, in this invention, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly and specifically defined.

[0027] In this invention, unless otherwise explicitly specified and limited, the terms "connection," "fixing," etc., should be interpreted broadly. For example, "fixing" can mean a fixed connection, a detachable connection, or an integral part; "connection" can mean a mechanical connection or an electrical connection. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0028] Combination Figures 1 to 7 This invention discloses a low-cost, explosion-proof delayed-action fuze for hand grenades, comprising a body 1, an ignition and explosion-proof module, a safety module, and an insensitive flame delay detonator module. The structure and principle of the ignition and explosion-proof module and the safety module are essentially the same as those of existing delayed-action fuzes for hand grenades (such as the American M201 series fuzes), including a firing pin 10, a flap 8, a pivot 2, a torsion spring 3, a grip 9, a safety pin 4, and a safety ring 12. Therefore, the main pre-throw operations, such as pulling out the safety pin and gripping the grip 9, remain unchanged, which helps users quickly and skillfully master the operation and usage requirements. The main difference is that the positions of the firing pin 10 and the impact cap 5 are interchanged spatially, thus increasing the explosion-proof function. The original sensitive impact delay detonator is correspondingly replaced with an insensitive flame delay detonator. A flame shield 13 and a quick-release pin 11 safety mechanism are also added. The body 1 needs to be modified to adapt to the new structure, but its main structure is basically the same as that of existing delayed-action fuze bodies 1 for hand grenades, and the height of the exposed portion is shortened.

[0029] Body 1 is the main structural component of the fuse, and it is provided with threads for connecting to the projectile. With the thread axis as the axis of symmetry, the outer contour of the body 1 is basically a body of revolution. Six through holes are provided along the axis from the top surface of the body 1, namely, the first-order hole, second-order hole, third-order hole, fourth-order hole, fifth-order hole, and sixth-order hole from top to bottom. A first transverse hole is provided on the body 1 near the position corresponding to half the depth of the first-order hole, along the radial direction and perpendicular to the axis (i.e., perpendicular to the plane of the paper). A second transverse hole is provided on the body 1 near the position corresponding to half the depth of the third-order hole, off the axis and outside the first transverse hole. A third transverse hole is provided outside the first transverse hole, between the first and second transverse holes, parallel to the first transverse hole. A cantilever protrusion parallel to the first transverse hole is provided on the other side symmetrical to the first transverse hole, at the outer edge of the body 1. The ignition and explosion-proof module is located inside the first, third, and fourth-order holes. The insensitive flame delay detonator 7 is located inside the sixth-order hole, and a safety module is used to protect the ignition and explosion-proof module.

[0030] The first horizontal hole of the main body 1 houses the rotating shaft 2 of the ignition and explosion-proof module, which is arranged around the first horizontal hole. The second horizontal hole of the main body 1 houses the safety pin 4 of the safety module of the ignition and explosion-proof module, and the third horizontal hole houses the quick-release pin 11 of the safety module of the ignition and explosion-proof module, which is arranged around the second horizontal hole. The quick-release pin is a mature technology that has been applied in various fields such as machinery manufacturing, aviation, road transportation, and automatic control.

[0031] Compared with existing non-explosion-proof grenade delay fuses such as the American M201 series fuses, this is equivalent to dividing the original sensitive impact delay detonator into two parts used in series: the input end becomes a sensitive impact cap 5, and the delay and output ends are sealed and insensitive flame delay detonators; a quick-release pin 11 is added above the safety pin 4, which is a safety device that is manually released by pressing and pulling out; before throwing, the end of the quick-release pin 11 must be pressed and the body 1 pulled out to release this safety first; the so-called insensitive flame delay detonator 7 means that the igniter, detonator, delayer and high explosive filled in it are all permissible in-line explosives with a sensitivity not higher than tertür.

[0032] Furthermore, the ignition and explosion-proof module includes a rotating shaft 2, a torsion spring 3, a flash cap seat 6, an impact flash cap 5, a flap 8, a firing pin 10, and a fireproof container 13. The rotating shaft 2 is disposed in the first transverse hole of the main body 1. The torsion spring 3 is pre-torsed and sleeved on the rotating shaft 2, with one end of the torsion spring 3 pressing on the flap 8 and the other end fixed by the main body 1. The impact flash cap 5 is riveted to the flash cap seat 6. The flash cap seat 6 is riveted to the flap 8. The bottom end of the firing pin 10 is fixed in the fireproof container 13. The firing pin 10 and the fireproof container 13 are riveted to the stepped surface between the fourth and fifth stage holes. The firing pin 10 has four eccentric axial fire transmission holes evenly distributed on it, with the pin tip facing upwards. The 0.05mm thick copper fireproof container 13 normally isolates the impact flash cap 5, and when the impact flash cap 5 ignites, it will directly break through the fire transmission holes.

[0033] Furthermore, the safety module includes a grip 9, a safety pin 4, a safety ring 12, and a quick-release pin 11. The safety pin 4 and the safety ring 12 are flexibly combined together. The safety pin 4 passes through the reserved hole on the grip 9 and is inserted into the second transverse hole on the body 1 to fix the grip 9 to the body 1. The main body of the grip 9 is close to the outer wall of the projectile and blocks the flash cap seat 6 of the firing and explosion-proof module to put it in a safe state. The hook at the front end of the grip 9 is hooked to the cantilever protrusion of the body 1. The quick-release pin 11 passes through the reserved hole of the grip 9, is inserted into the third transverse hole, and passes out from the reserved hole of the grip 9 on the other side. Its self-locking structure can prevent it from falling off.

[0034] Furthermore, the safety pin 4 and quick-release pin 11 together form a redundant safety mechanism for the flap 8. Manually releasing the safety pin 4, i.e., pulling it out of the body 1 to release the grip 9 and flap 8, requires first rotating the safety pin 4 with a certain torque. Similarly, manually releasing the quick-release pin 11, i.e., pulling it out of the body 1 to release the grip 9 and flap 8, requires first pressing the center contact point of the quick-release pin 11, in the opposite direction to the pulling direction, with the contact point recessed into the end face of the quick-release pin. It is evident that these two sets of manually released safety mechanisms significantly reduce the possibility of operational errors.

[0035] Furthermore, the insensitive delayed detonator includes a casing 77, and a reinforcing cap 71, an insensitive high explosive 72, a first insensitive ignition charge 73, an insensitive delayed charge 74, a barrier plate 75, and a second insensitive ignition charge 76, sequentially arranged within the casing 77 from the output end to the input end. The insensitive flame delayed detonator 7 is riveted downwards into a sixth-order hole. The insensitive agents in the insensitive delayed detonator have a sensitivity not exceeding that of tertrol, meeting the sensitivity limits for inline explosive charges in GJB3194-1998 "Safety Design Guidelines for Manually Deployed Weapons".

[0036] Furthermore, the positions of the firing pin 10 and the impact cap 5 are interchanged in terms of spatial layout. The firing pin 10 is aligned above the insensitive flame delay detonator 7, while the impact cap 5 is fixed on the flip plate 8, offset and away from the firing pin 10 and the insensitive flame delay detonator 7. Explosion-proof safety is achieved through the principle of spatial isolation. Even if the impact cap 5 accidentally ignites in the explosion-proof position, it will not trigger the insensitive flame delay detonator 7, which is offset and prevented from spreading by the flame shield. This ingeniously achieves the explosion-proof safety design.

[0037] The aforementioned insensitive high explosive 72 can be a mixed explosive such as DH-5, JO-9, or HNS. The aforementioned insensitive igniter can be a boron / potassium nitrate igniter. The aforementioned insensitive delay charge 74 can be a tungsten-based delay charge with diatomaceous earth and shellac as insensitive agents (when excluding the insensitive agent, the proportion is approximately 37.6% tungsten powder, 10.6% potassium perchlorate, and 51.8% barium chromate).

[0038] The innovation of this invention lies in the fact that, without changing the shape, weight, interface with the grenade, or the main operating steps, the positions of the firing pin and the impact cap in the original classic structure are interchanged. The original sensitive impact delay detonator is correspondingly replaced with a blunt-sensitive flame delay detonator 7, and a quick-release pin 11 is added next to the safety pin 4. This achieves the requirements of explosion-proof and redundant safety design, ensuring safety during storage, transportation, and use. The lack of increased exposed height helps to balance the mass and aerodynamic characteristics of the grenade, thus not affecting throwing accuracy. It inherits the impact ignition principle, ensuring the safety of handling unexploded ordnance. The structure is simple and the cost is low.

[0039] The main safety principle of the explosion-proof, low-cost time-delay fuze for hand grenades of this invention is as follows:

[0040] During service, the fuze is in its explosion-proof state, i.e., its factory-assembled state. The safety pin 4 and quick-release pin 11 redundantly protect the flap 8 and its impact cap 5 at a position offset from the insensitive flame delay detonator 7. The fuze meets the requirement of a safe failure rate of less than one in a million. The fuze will not accidentally detonate even under reliable shocks, vibrations, impacts, and drops. Even if the impact cap 5 accidentally ignites, it will not trigger the insensitive flame delay detonator 7 located in the sixth-order hole, thus preventing the explosive charge within the grenade warhead from igniting.

[0041] A fire shield 13 made of copper is added to the bottom of the firing pin 10. Normally, it isolates the flame generated by accidental ignition of the impact cap 5. When the impact cap 5 is aligned with the desensitized flame delay detonator 7 and ignites normally, it will directly break through the fire shield and trigger the desensitized flame delay detonator 7 through the axial ignition hole on the side of the firing pin 10.

[0042] The quick-release pin 11 and the safety pin 4 pass sequentially through the grip 9 and the body 1, constraining the grip 9 to the body 1. At this time, the grip 9 presses against the primer seat 6, the safety pin 4, and the quick-release pin 11, also preventing the flap 8 from flipping over. The ignition and explosion-proof mechanism of the fuze is in a safe and explosion-proof state. The safety ring 12 is normally flipped onto the protrusion on the side of the body 1, with a certain interference fit to generate elastic tension and prevent the user from accidentally removing the safety pin 4 due to reliable tactical actions, thus accidentally disengaging the safety. Under reliable operational impact environments such as vibration, shock, impact, and accidental drops, the fuze can still maintain the above state.

[0043] The fuse structure is completely open. Any one or more of the safety pin 4, safety ring 12, and quick-release pin 11 that are missing or incorrectly installed can be detected through visual inspection and parts counting, thus preventing misinstallation. The fuse structure is simple and robust. From the side of the handle, it is possible to observe whether the flap is in the assembled position, i.e., whether it is in a safe state of explosion-proof and safety protection; its function is equivalent to a working status indicator.

[0044] The insensitive flame delay detonator 7 adopts a closed input end and a closed output end structure, which avoids the potential ignition path of the fuse in the explosion-proof state and improves the explosion-proof safety.

[0045] The requirement for safe separation of the grenade from the thrower is achieved by the delay function of the detonator 7, which is a ... a delay function of the detonator 7, which is a delay function of the detonator 7.

[0046] The casing 77 is made of high-strength steel with a relatively thick wall. Therefore, while ensuring the reliable transition from combustion to detonation of the detonator 7 with its insensitive flame delay, it also possesses insensitivity characteristics, i.e., low vulnerability, enabling it to withstand extreme environments such as rapid heating, slow heating, gunfire, fragmentation impact, and jet shock. The casing 77 is coated internally and externally with certain heat-insulating and cushioning materials, which further contributes to achieving the aforementioned insensitivity and low vulnerability characteristics.

[0047] The fuse ignition employs an impact ignition principle where the firing pin 10 strikes the sensitive impact cap 5. This requires significant energy for ignition, and the sensitive impact cap 5 ignites through multiple hot spots, ensuring high reliability. Furthermore, in the event of a misfire, the firing pin 10 will not re-ignite the sensitive impact cap 5 under subsequent reliable impact conditions such as vibration, shock, impact, or accidental drop. Therefore, by inheriting the impact ignition principle instead of switching to a lower-energy needle-punch ignition principle, the original superior unexploded ordnance explosive handling characteristics are preserved.

[0048] If the thrown fuse fails to ignite, resulting in an unexploded ordnance, the fuse associated with the unexploded ordnance can be observed, provided one's own safety is ensured. If the grip 9 fails to detach and thus the flap 8 cannot be released, it can be placed into an explosion-proof container within the shortest possible timeframe (e.g., 2 seconds), allowing it to detach from the grip 9 during placement and release the flap 8, which will then detonate within the container at a set time. If the flap 8, along with its impact cap 5, has struck the firing pin 10, but the impact cap 5 has failed to ignite, the flap 8 can be reset, and the pre-prepared safety pin 4 and quick-release pin 11 can be inserted. The fuse will then be restored to its safe and explosion-proof state (it would be even better if the grip 9 could be retrieved or prepared in advance and reinstalled), allowing for subsequent safe disposal of explosives. If the impact cap 5 has ignited, but the insensitive delayed-action detonator 7 does not detonate, the fuse has entered an insulated state, ensuring the safety of subsequent explosive disposal.

[0049] The working process of the explosion-proof, low-cost time-delay fuse for hand grenades of the present invention is as follows:

[0050] Before use, press the button at the end of the quick-release pin 11. After its internal locking mechanism is disengaged, pull it off the body 1 and the grip 9. This releases the first safety mechanism of the fuse. Before throwing, after gripping the grip 9, pull the safety ring 12 along with its associated safety pin 4 off the grenade to release the second safety mechanism. The grenade is now ready to be thrown. From this point until throwing, the grip 9 should be held firmly and not released. Only release the grip 9 for a split second before the grenade is released. After being thrown, the grip 9 is pushed by the flap 8 and subjected to air resistance, and falls off in the air. The torsion spring 3 in the pre-torsion state rotates around the rotating shaft 2, driving the flap 8 to rotate the percussion cap seat 6 and the sensitive impact percussion cap 5 inside to strike the firing pin 10. This causes the sensitive impact percussion cap 5 to ignite. The high temperature and high pressure gas generated passes through the axial ignition hole on the side of the firing pin and then breaks through the flame shield 13, triggering the second insensitive ignition charge 76 in the insensitive flame delay detonator 7. The flame generated passes through the barrier and ignites the insensitive delay charge 74. The insensitive delay charge 74 burns for several seconds, and then, through the combustion and detonation effect of the first insensitive ignition charge 73, it finally detonates the insensitive high explosive charge 72. The insensitive delay detonator 7 completes its function and detonates the explosive charge inside the grenade.

[0051] The design and application of torsion spring 3 meet the requirements of GJB3194-1998 "Safety Design Guidelines for Manually Deployed Weapons" regarding the application of internal energy storage.

Claims

1. A low-cost, explosion-proof time-delay fuse for hand grenades, characterized in that: The device includes a main body (1), an ignition and explosion-proof module, a safety module, and an insensitive flame delay detonator (7). The main body (1) has six through holes along its axis on its top surface, numbered from top to bottom as the first, second, third, fourth, fifth, and sixth through holes. A first transverse hole is located on the main body (1) near the axis, corresponding to half the depth of the first through hole, along the radial and axial perpendicular directions. A second transverse hole is located on the main body (1) near the axis, outside the first transverse hole, corresponding to half the depth of the third through hole, parallel to the first transverse hole. A third transverse hole is located outside the first transverse hole, between the first and second transverse holes, parallel to the first transverse hole. A cantilever protrusion parallel to the first transverse hole is located on the outer edge of the main body (1), symmetrical to the first transverse hole. The ignition and explosion-proof module is located within the first, third, and fourth through holes. The insensitive flame delay detonator (7) is located within the sixth through hole, and the safety module is used to protect the ignition and explosion-proof module. The ignition and explosion-proof module includes a rotating shaft (2), a torsion spring (3), a flash cap seat (6), an impact flash cap (5), a flap (8), a firing pin (10), and a fireproof container (13); the rotating shaft (2) is located in the first transverse hole of the main body (1); the torsion spring (3) is pre-torsed and fitted onto the rotating shaft (2), with one end of the torsion spring (3) pressing against the flap (8) and the other end fixed by the main body (1); the impact flash cap (5) is riveted and fixed inside the flash cap seat (6). The spark cap holder (6) is fixed to the flap (8) by riveting; the bottom end of the striker (10) is fixed inside the fire shield (13); the striker (10) and the fire shield (13) are riveted to the step surface between the fourth and fifth holes; four eccentric axial fire transmission holes are evenly distributed on the striker (10), with the needle tip facing upward; the fire shield (13) normally isolates the impact spark cap (5), and when the impact spark cap (5) is ignited, it will be directly broken through the fire transmission hole; In terms of spatial layout, the positions of the firing pin (10) and the impact cap (5) are interchanged. The firing pin (10) is aligned above the insensitive flame delay detonator (7), and the impact cap (5) is fixed on the flap (8), offset and away from the firing pin (10) and the insensitive flame delay detonator (7).

2. The explosion-proof, low-cost time-delay fuze for hand grenades according to claim 1, characterized in that: The insensitive flame delay detonator (7) includes a tube shell (77), and a reinforcing cap (71), an insensitive high explosive (72), a first insensitive ignition charge (73), an insensitive delay charge (74), a barrier plate (75), and a second insensitive ignition charge (76) arranged sequentially in the tube shell (77) from the output end to the input end. The mouth of the insensitive flame delay detonator (7) is riveted downwards and placed in the sixth-order hole.

3. The explosion-proof, low-cost time-delay fuze for hand grenades according to claim 2, characterized in that: The safety module includes a grip (9), a safety pin (4), a safety ring (12), and a quick-release pin (11). The safety pin (4) and the safety ring (12) are flexibly combined together. The safety pin (4) passes through the reserved hole on the grip (9) and is inserted into the second transverse hole on the body (1) to fix the grip (9) on the body (1). The main body of the grip (9) is attached to the outer wall of the projectile and blocks the flash cap seat (6) of the firing and explosion-proof module to keep it in a safe state. The hook at the front end of the grip (9) is hooked to the cantilever protrusion of the body (1). The quick-release pin (11) passes through the reserved hole of the grip (9), is inserted into the third transverse hole, and passes out from the reserved hole of the grip (9) on the other side. Its self-locking structure can prevent it from falling off.

4. The explosion-proof, low-cost time-delay fuze for hand grenades according to claim 3, characterized in that: The safety pin (4) and the quick-release pin (11) together form a redundant safety for the flap (8).

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