Hot start switch suitable for airborne fire extinguishing aerial bomb
By designing a hot-start switch that utilizes the flame temperature sensing element of the airborne fire extinguishing bomb's thermal bimetallic strip assembly, reliable activation of the fire extinguishing bomb is achieved. This solves the problem of low safety caused by the single environmental force in existing technologies, and improves the safety and reliability of the fire extinguishing bomb.
Patent Information
- Application Number
- CN202422928284.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-28
- Publication Date
- 2026-01-06
- Estimated Expiration
- 2034-11-28
AI Technical Summary
The environmental forces of existing airborne fire extinguishing bombs are relatively simple, resulting in low safety and the electrical fuses are prone to premature tripping, posing a safety hazard.
A thermal start switch suitable for airborne fire extinguishing bombs was designed. It uses a thermal bimetallic strip assembly to sense the flame temperature. By using the difference in thermal expansion coefficients between the active and passive metal strips, the active striking body is pushed to bring the positive electrode component into contact with the negative electrode component, thereby achieving reliable closure of the switch.
Ensuring reliable activation of fire extinguishing bombs in high-temperature environments improves safety and reliability, and avoids the safety hazards of premature activation of fire extinguishing bombs.
Smart Images
Figure CN223760263U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to a start switch, and more particularly to a hot start switch suitable for airborne fire extinguishing bombs, belonging to the field of forest fire extinguishing technology. Background Technology
[0002] Forest fires are difficult to control, spread freely and rapidly within forests, and are characterized by their suddenness, high frequency, wide affected area, great destructiveness, rapid spread, and difficulty in extinguishing. Once a forest fire occurs, it will cause serious damage to forests and the ecological environment, resulting in huge economic losses.
[0003] Forest fires are generally classified into three types based on their combustibles and location: surface fires, crown fires, and underground fires. Crown fires, burning within the tree canopy, exhibit completely different combustion characteristics from surface and underground fires. They are characterized by high temperatures, intense flames, rapid spread, and a tendency to trigger unusual fire behaviors. In my country, most tree canopies are approximately 20 to 40 meters high. Crown fires at this height can generate powerful convection columns, which develop rapidly during large fires. Due to buoyancy, these columns often carry large amounts of burning combustibles, which are then carried to unburned combustibles in front of the flames, causing flying embers. When multiple flying embers occur simultaneously, a fire explosion can occur. Once a fire explosion occurs, it can create a fire vortex, a high-speed rotating hot airflow with horizontal wind speeds exceeding 10 m / s. Among all types of forest fires, crown fires are the most destructive and difficult to extinguish, often becoming a major contributing factor to catastrophic forest fires. Existing firefighting equipment is unable to directly and effectively extinguish them.
[0004] Currently, a wide variety of airborne forest firefighting equipment has been developed, each with different functions. However, due to the limited environmental forces on bomb- or drone-borne equipment, safety mechanisms rely solely on gravity to disengage the electrical fuse. Furthermore, premature disengagement of the electrical fuse can lead to premature activation of the fire extinguishing bomb, posing a safety hazard to the airborne equipment. Therefore, the safety of these products cannot meet the usage requirements, necessitating the development of a device that disengages the electrical fuse using external environmental forces. This invention proposes a thermal start switch suitable for airborne fire extinguishing bombs. Utility Model Content
[0005] The purpose of this invention is to address the problem that existing airborne bombs or UAVs have limited environmental forces, leading to low safety. This invention proposes a thermal start switch suitable for airborne fire extinguishing bombs, which uses the hot airflow of the flame to activate the electrical safety switch of the fire extinguishing bomb, ensuring that the fire extinguishing bomb can be activated in real time after the safety is released.
[0006] The objective of this utility model is achieved through the following technical solution.
[0007] This utility model proposes a thermal start switch suitable for airborne fire extinguishing bombs, comprising: a thermal bimetallic strip assembly, a positive electrode component, a negative electrode component, a live impactor, a warhead, a warhead, an active metal strip, a passive metal strip, an electrical contact, a positive electrode plate, a positive electrode rod, an electrical contact head, a negative electrode plate, and a negative electrode rod.
[0008] The piston body adopts a stepped boss structure with stepped holes sequentially opened along the large end face of the piston body. The holes are named as first stepped hole, second stepped hole, third stepped hole, and fourth stepped hole according to their diameter from large to small. The first stepped hole is used to place the positive electrode component. Several small threaded holes are evenly distributed on the circular axial surface at a certain distance from the center of the bottom of the first stepped hole. These holes are used to fix the positive electrode component to the bottom of the first stepped hole with connecting screws. The second and third stepped holes are clearance holes. The fourth stepped hole is a threaded through hole used to fix it to the bimetallic strip assembly with connecting screws.
[0009] The projectile is a hollow frustum-shaped structure with an annular groove extending upwards from the top. The horizontal cap of the bimetallic strip assembly is embedded in the annular groove and riveted in place. Stepped holes are sequentially formed upwards from the bottom of the frustum, named as the first stepped hole, second stepped hole, and third stepped hole according to their diameter from largest to smallest. The first stepped hole has an internal thread for fixed connection with the external thread of the projectile head. The second and third stepped holes are clearance holes for the passage of the live part containing the positive electrode component.
[0010] The projectile body is a conical structure with a boss at the head. The boss has an external thread for fixed connection with the internal thread of the first stepped hole at the bottom of the projectile. Stepped holes are opened sequentially from the bottom of the projectile body upwards. They are named the first stepped hole, the second stepped hole, and the third stepped hole according to the hole diameter from large to small. The first stepped hole is a clearance hole. Several small threaded holes are evenly distributed on the circular axial surface at a certain distance from the center at the bottom of the second stepped hole. They are used to fix the negative electrode component to the bottom of the second stepped hole by connecting screws. The third stepped hole is a through hole.
[0011] The thermal bimetallic strip assembly is arc-shaped with a horizontal cap edge around its perimeter. The horizontal cap edge is embedded in the annular groove structure at the top of the projectile. The thermal bimetallic strip assembly includes an active metal strip and a passive metal strip arranged in layers. The top of the arc-shaped surfaces of the active and passive metal strips are provided with circular holes. Connecting screws are used to pass through the active metal strip, the passive metal strip, and the head of the firing body in sequence to connect the three. The active and passive metal strips have different coefficients of thermal expansion. When the temperature rises, the deformation of the active metal strip is greater than that of the passive metal strip. The thermal bimetallic strip assembly bends towards one side of the passive metal strip, pushing the firing body to move together with the positive electrode component, so that the contact of the positive electrode component contacts the contact of the negative electrode component, thereby achieving the closure of the thermal start switch.
[0012] The positive electrode plate is a non-metallic circular thin plate with a central hole. A ring of pads is arranged along the outer edge of the central hole. The contact body adopts a boss structure, with one end of a small cylinder passing through the central hole of the positive electrode plate. The stepped surface of the large cylinder is welded and fixed to the pad in the center of the positive electrode plate. A pad is arranged on the side at a certain distance from the center of the positive electrode plate for welding the positive electrode rod. The two pads are connected. The surface of the contact body is coated with a highly conductive coating to ensure reliable connection between the two stages when the switch is closed.
[0013] The negative electrode plate is a non-metallic circular thin plate with a central hole. A ring of pads is arranged around the outer edge of the central hole. The connector adopts a cylindrical structure with a hemispherical head and a boss at the bottom. The central hole of the negative electrode plate is used for the connector to pass through. The boss of the connector is welded and fixed to the central pad of the negative electrode plate. The negative electrode rod is welded to the boss of the connector. A small hole is made at a certain distance from the center of the negative electrode plate for the positive electrode rod to pass through. The surface of the connector is coated with a highly conductive coating to ensure reliable connection between the two electrodes when the switch is closed.
[0014] Working principle
[0015] When a fire-extinguishing aerial bomb flies over a forest fire, especially a crown fire (where temperatures can reach 900℃-1500℃), the thermal start switch on the bomb's nose absorbs the heat flowing through the flames surrounding the bomb. This causes the temperature of the bimetallic strip assembly to rise rapidly. Utilizing the difference in thermal expansion coefficients between the active and passive metal strips, the active metal strip deforms more than the passive metal strip when the temperature rises. As a result, the bimetallic strip assembly bends towards the passive metal strip, pushing the active electrode to move along with the positive electrode component. This brings the contact point of the positive electrode component into contact with the contact head of the negative electrode component, thus closing the thermal start switch.
[0016] Beneficial effects
[0017] 1. The present invention provides a thermal start switch for airborne fire extinguishing bombs, which uses the temperature of crown fire, which can reach 900℃-1500℃, as an external environmental force to activate the switch.
[0018] 2. The present invention provides a thermal start switch suitable for airborne fire extinguishing bombs. The thermal bimetallic strip assembly, the positive electrode component, and the negative electrode component form a low-frequency "spring-mass-damping" structure. The head of the electrical contact adopts a hemispherical structure, which enables the thermal start switch to complete a reliable "point-to-surface" closure after sensing the temperature through the deformation of the thermal bimetallic strip assembly.
[0019] 3. The present invention provides a hot start switch suitable for airborne fire extinguishing bombs, which not only enables reliable switch closure but also has the advantages of light weight, simple structure, good safety, and high reliability. Attached Figure Description
[0020] Figure 1 This is a front view of the hot start switch for airborne fire extinguishing bombs according to this utility model;
[0021] Figure 2 This is a schematic diagram of the structure of the hot bimetallic strip assembly in the hot start switch of the airborne fire extinguishing bomb of this utility model;
[0022] Figure 3 This is a schematic diagram of the structure of the positive electrode component in the hot start switch of an airborne fire extinguishing bomb, which is applicable to this utility model.
[0023] Figure 4 This is a schematic diagram of the structure of the negative electrode component in the hot start switch of an airborne fire extinguishing bomb.
[0024] The numbers in the diagram are: 1-Thermal bimetallic strip assembly, 2-Positive electrode connection component, 3-Negative electrode connection component, 4-Active striking body, 5-Projectile head, 6-Projectile body, 7-Active metal strip, 8-Passive metal strip, 9-Electrifying body, 10-Positive electrode plate, 11-Positive electrode rod, 12-Electrifying head, 13-Negative electrode plate, 14-Negative electrode rod. Detailed Implementation
[0025] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.
[0026] Example
[0027] Combination Figures 1-4 The present invention proposes a thermal start switch suitable for airborne fire extinguishing bombs, comprising: a thermal bimetallic strip assembly 1, a positive electrode component 2, a negative electrode component 3, a live impactor 4, a warhead 5, a warhead 6, an active metal strip 7, a passive metal strip 8, an electrical contact 9, a positive electrode plate 10, a positive electrode rod 11, an electrical contact head 12, a negative electrode plate 13, and a negative electrode rod 14.
[0028] The piston body 4 adopts a stepped boss structure with stepped cross-section. Stepped holes are sequentially opened along the large end face of the piston body 4, and are named as first stepped hole, second stepped hole, third stepped hole and fourth stepped hole respectively according to the hole diameter from large to small. The first stepped hole is used to place the positive electrode component 2. Several small threaded holes are evenly distributed on the circular axial surface at a certain distance from the center of the bottom of the first stepped hole, which are used to fix the positive electrode component 2 to the bottom of the first stepped hole by connecting screws. The second and third stepped holes are clearance holes. The fourth stepped hole is a threaded through hole, which is used to fix it to the hot bimetallic strip assembly 1 by connecting screws.
[0029] The projectile 5 is a hollow frustoconical structure with an annular groove structure opened upward from the top of the projectile 5. The horizontal cap edge of the hot bimetallic strip assembly 1 is embedded in the annular groove and riveted to fix it. Stepped holes are opened sequentially upward from the bottom of the frustum of the projectile 5, and are named the first stepped hole, the second stepped hole, and the third stepped hole according to the hole diameter from large to small. The first stepped hole is provided with an internal thread for fixed connection with the external thread of the head of the projectile body 6. The second stepped hole and the third stepped hole are clearance holes for the passage of the live striking body 4, which is equipped with the positive electrode component 2.
[0030] The projectile 6 is a conical structure with a boss at the head. The boss has an external thread for fixed connection with the internal thread of the first stepped hole at the bottom of the projectile 5. Stepped holes are opened sequentially from the bottom of the projectile 6 upwards. They are named the first stepped hole, the second stepped hole, and the third stepped hole according to the diameter from large to small. The first stepped hole is a clearance hole. Several small threaded holes are evenly distributed on the circular axial surface at a certain distance from the center at the bottom of the second stepped hole. They are used to fix the negative electrode component 3 to the bottom of the second stepped hole by connecting screws. The third stepped hole is a through hole.
[0031] The thermal bimetallic strip assembly 1 is arc-shaped with a horizontal cap edge around its perimeter. The horizontal cap edge is embedded in the annular groove structure at the top of the bullet head 5. The thermal bimetallic strip assembly 1 includes an active metal strip 7 and a passive metal strip 8 arranged in layers. The top of the arc-shaped surfaces of the active metal strip 7 and the passive metal strip 8 are provided with round holes. Connecting screws are used to pass through the active metal strip 7, the passive metal strip 8 and the head of the live striker 4 in sequence to connect the three. The active metal strip 7 and the passive metal strip 8 have different coefficients of thermal expansion. When the temperature rises, the deformation of the active metal strip 7 is greater than that of the passive metal strip 8. The thermal bimetallic strip assembly 1 bends towards the passive metal strip 8, pushing the live striker 4 to move together with the positive electrode component 2, so that the contact body 9 of the positive electrode component 2 contacts the contact head 12 of the negative electrode component 3, thereby realizing the closure of the thermal start switch.
[0032] The positive electrode plate 10 is a non-metallic circular thin plate with a central hole. A ring of pads is arranged along the outer edge of the central hole. The contact body 9 adopts a boss structure. One end of the small cylinder passes through the central hole of the positive electrode plate 10. The stepped surface of the large cylinder is welded and fixed to the pad at the center of the positive electrode plate 10. A pad is arranged laterally at a certain distance from the center of the positive electrode plate 10 for welding the positive electrode rod 11. The two pads are connected. The surface of the contact body 9 is coated with a highly conductive coating to ensure reliable connection between the two stages when the switch is closed.
[0033] The negative electrode plate 13 is a non-metallic circular thin plate with a central hole. A ring of pads is arranged around the outer edge of the central hole. The connector 12 adopts a cylindrical structure with a hemispherical head and a boss at the bottom. The central hole of the negative electrode plate 13 is used for the connector 12 to pass through. The boss of the connector 12 is welded and fixed to the central pad of the negative electrode plate 13. The negative electrode rod 14 is welded to the boss of the connector 12. A small hole is made at a certain distance from the center of the negative electrode plate 13 for the positive electrode rod 11 to pass through. The surface of the connector 12 is coated with a highly conductive coating to ensure reliable connection between the two electrodes when the switch is closed.
[0034] The hot start switch is installed at the head of the fire extinguishing projectile during use;
[0035] During assembly, a small amount of epoxy resin adhesive is applied between the connecting surfaces of the active metal sheet 7 and the passive metal sheet 8 to bond the active metal sheet 7 and the passive metal sheet 8 together. After curing for 24 hours, a thermo-bimetallic composite 1 is formed.
[0036] First, pass one end of the small cylindrical part of the power connector 9 through the center hole of the positive electrode plate 10, and then reliably weld the protruding surface of the power connector 9 onto the pad at the center of the positive electrode plate 10; then weld and fix the positive electrode guide rod 11 onto the transverse pad at a certain distance from the center of the positive electrode plate 10 to form the positive electrode component 2.
[0037] First, pass the end of the connector 12 with the hemispherical surface through the center hole of the negative electrode plate 13, and then reliably weld the boss surface of the connector 12 to the pad in the center of the negative electrode plate 13; then weld the negative electrode guide rod 14 to the boss of the connector 12 to form the negative electrode component 3.
[0038] First, assemble the bimetallic strip assembly 1 into the annular groove of the projectile 5, and use a tool to tighten the bimetallic strip assembly 1 into the annular groove at the head of the projectile 5. Then, use a special tool to assemble the piston 4 and the bimetallic strip assembly 1 into place, and use connecting screws coated with a small amount of epoxy resin to fix them. Use connecting screws coated with a small amount of epoxy resin to fix the positive electrode component 2 onto the first stepped hole of the piston 4. Connect the projectile 5, which contains the bimetallic strip assembly 1, the piston 4, and the positive electrode component 2, to the projectile body 6 through threads. Finally, after passing the positive electrode guide rod 11 on the positive electrode component 2 through the small hole of the negative electrode plate 13, use connecting screws coated with a small amount of epoxy resin to fix the negative electrode component 3 onto the second stepped hole at the bottom of the projectile body 6.
[0039] Working principle
[0040] When the fire extinguishing bomb flies over a forest fire, especially a crown fire (where the temperature can reach 900℃-1500℃), the thermal start switch at the head of the fire extinguishing bomb absorbs the heat flowing through the flames around the bomb. As a result, the temperature of the thermal bimetallic strip assembly 1 rises rapidly. Due to the difference in thermal expansion coefficients between the active metal strip 7 and the passive metal strip 8, the deformation of the active metal strip 7 is greater than that of the passive metal strip 8 when the temperature rises. As a result, the thermal bimetallic strip assembly 1 bends toward the passive metal strip 8, pushing the active body 4 to move together with the positive electrode component 2. This causes the contact body 9 of the positive electrode component 2 to contact the contact head 12 of the negative electrode component 3, thus closing the thermal start switch.
[0041] The above description is only a preferred embodiment of the present utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present utility model, and these improvements and modifications should also be considered within the protection scope of the present utility model.
Claims
1. A thermal start switch for use in an airborne fire-extinguishing projectile, comprising: The utility model relates to a thermal bimetallic piece assembly, a power connection positive pole part, a power connection negative pole part, a striker, a bullet head, a bullet body, a driving metal sheet, a passive metal sheet, a power connection body, a power connection positive pole plate, a positive pole guide rod, a power connection head, a power connection negative pole plate, a negative pole guide rod, and the utility model relates to a thermal bimetallic piece assembly, a power connection positive pole part, a power connection negative pole part, a striker, a bullet head, a bullet body, a driving metal sheet, a passive metal sheet, a power connection body, a power connection positive pole plate, a positive pole guide rod, a power connection head, a power connection negative pole plate, a negative pole guide rod. The striker adopts a convex platform structure with a stepped cross section, a stepped hole is sequentially formed on the upper end surface of the striker, and the stepped hole is sequentially named as a first stepped hole, a second stepped hole, a third stepped hole and a fourth stepped hole according to the hole diameter from large to small; the first stepped hole is used for placing the power connection positive pole part, a plurality of small screw holes are uniformly arranged on the bottom of the first stepped hole along the central circular surface, and the power connection positive pole part is fixed on the bottom of the first stepped hole through connecting screws; the second stepped hole and the third stepped hole are clearance holes; the fourth stepped hole is a threaded hole, and the thermal bimetallic piece assembly is fixed through connecting screws. The bullet head is a hollow frustoconical structure, a ring-shaped groove structure is formed on the top of the bullet head, the horizontal cap of the thermal bimetallic piece assembly is embedded in the ring-shaped groove structure and is riveted and fixed, stepped holes are sequentially formed on the bottom of the bullet head, and the stepped holes are sequentially named as a first stepped hole, a second stepped hole and a third stepped hole according to the hole diameter from large to small; the first stepped hole is provided with internal threads and is used for fixed connection with external threads of the bullet body head; the second stepped hole and the third stepped hole are clearance holes and are used for the striker with the power connection positive pole part to pass through; The bullet body is a conical structure with a convex platform arranged on the head, the convex platform is provided with external threads and is used for fixed connection with internal threads of the first stepped hole at the bottom of the bullet head; stepped holes are sequentially formed on the bottom of the bullet body, and the stepped holes are sequentially named as a first stepped hole, a second stepped hole and a third stepped hole according to the hole diameter from large to small; the first stepped hole is a clearance hole, a plurality of small screw holes are uniformly arranged on the bottom of the second stepped hole along the central circular surface, and the power connection negative pole part is fixed on the bottom of the second stepped hole through connecting screws; the third stepped hole is a through hole; The thermal bimetallic piece assembly is arc-shaped, a horizontal cap is arranged on the periphery of the thermal bimetallic piece assembly, the horizontal cap is embedded in the ring-shaped groove structure on the top of the bullet head, the thermal bimetallic piece assembly comprises a driving metal sheet and a passive metal sheet arranged in layers, a circular hole is formed on the top of the arc-shaped surface of the driving metal sheet and the passive metal sheet, connecting screws are sequentially passed through the driving metal sheet, the passive metal sheet and the head of the striker to connect the three; the thermal expansion coefficients of the driving metal sheet and the passive metal sheet are different, when the temperature rises, the deformation of the driving metal sheet is greater than that of the passive metal sheet, the thermal bimetallic piece assembly bends to the side of the passive metal sheet, pushes the striker to move together with the power connection positive pole part, the power connection body of the power connection positive pole part contacts the power connection head of the power connection negative pole part, and the thermal starting switch is closed. The power connection positive plate is a non-metallic circular thin plate, the center of the power connection positive plate is provided with a center hole, a circle of welding pads are arranged along the outer edge of the center hole, the power connection body adopts a boss structure, a small cylinder passes through the center hole of the power connection positive plate at one end; the stepped surface of the large cylinder is welded and fixed on the welding pads in the center of the power connection positive plate; a welding pad is arranged laterally at a certain distance from the center of the power connection positive plate, which is used for welding the positive pole guide rod, and the two welding pads are communicated; the surface of the power connection body is plated with a strong conductive coating layer, which is used for reliable communication between the two levels when the switch is closed; The power connection negative plate is a non-metallic circular thin plate, the center of the power connection negative plate is provided with a center hole, a circle of welding pads are arranged along the outer edge of the center hole, the power connection head adopts a cylindrical structure with a hemispherical head, the bottom of the cylinder is provided with a boss, the center hole of the power connection negative plate is used for the power connection head to pass through; the boss of the power connection head is welded and fixed with the center welding pad of the power connection negative plate; the negative pole guide rod is welded on the boss of the power connection head; a small hole is arranged at a certain distance from the center of the power connection negative plate, which is used for the positive pole guide rod to pass through; the surface of the power connection head is plated with a strong conductive coating layer, which is used for reliable communication between the two levels when the switch is closed.
2. A thermal trigger switch for use in an airborne fire-extinguishing projectile as defined in claim 1, wherein: A small amount of epoxy resin glue is coated between the connecting surfaces of the active metal sheet and the passive metal sheet, the active metal sheet and the passive metal sheet are bonded together, and cured for 24 hours to form a thermal bimetallic sheet assembly.
3. A thermal trigger switch for use in an airborne fire-extinguishing projectile as defined in claim 1 or 2, characterized in that A small amount of epoxy resin glue is coated on the connecting screw.