A safety device based on shape memory alloys

Abstract

The application relates to a shape memory alloy-based safety device, which comprises a first terminal, a second terminal and a connecting piece fixed between the first terminal and the second terminal; the connecting piece comprises an insulating shell, an insulating bending plate and a shape memory alloy piece located in a cavity of the shell; the bending plate is used for limiting the shape memory alloy piece, so that circuit breaking is realized. The shape memory alloy-based safety device designed by the application can solve the problems that the existing one-time fuse has low conduction loss but cannot be reset, the reset type thermal protector has a relatively complex structure, the contact resistance is relatively high, and the thermal protector needs to maintain temperature or external force to keep the circuit breaking after being disconnected; the partial electronic protection scheme needs continuous power supply, has standby loss and additionally increases cost.

Description

Technical Field

[0001] This invention relates to the field of circuit protection technology, and more specifically to a safety device based on shape memory alloy. Background Technology

[0002] Existing circuit protection components, such as one-time fuses, resettable thermal protectors, and bimetallic circuit breakers, involve trade-offs in terms of size, resettlement capability, conduction loss, post-trigger state retention, and structural complexity: one-time fuses have low conduction loss but are not resettable; resettable thermal protectors have relatively complex structures, high contact resistance, and often require temperature maintenance or external force to maintain the open circuit after disconnection; some electronic protection schemes require continuous power supply, resulting in standby losses and additional costs.

[0003] Therefore, existing technologies have shortcomings and need to be improved and developed. Summary of the Invention

[0004] The present invention provides a safety device based on shape memory alloy to address the problems of existing technologies such as: one-time fuses having low conduction loss but being non-resettable; resettable thermal protectors having relatively complex structures, high contact resistance, and often requiring temperature maintenance or external force to maintain the open circuit after disconnection; and some electronic protection schemes requiring continuous power supply, resulting in standby losses and additional costs.

[0005] This invention provides a safety device based on shape memory alloy, comprising a first terminal, a second terminal, and a connector fixed between the first terminal and the second terminal; the connector includes an insulating shell and an insulating bent plate, the shell having a cavity, with a first opening and a second opening respectively at the two ends of the cavity facing the first terminal and the second terminal; the bent plate includes a first bent portion and a second bent portion, the upper surface of the shell near the first terminal having a slot adapted to the shape of the second bent portion, one end of the first bent portion being fixedly connected to the upper surface of the shell, and the other end of the first bent portion being connected to the second bent portion to enable... The second bending portion extends into the slot; a shape memory alloy sheet is arranged inside the cavity, one end of the shape memory alloy sheet is a fixed end, the fixed end extends out of the second opening and is fixedly connected to the second terminal, the other end of the shape memory alloy sheet is a free end and has two memory positions, when the shape memory alloy sheet is in the first memory position, the free end extends out of the first opening and contacts the second terminal, and the second bending portion contacts the upper surface of the shape memory alloy sheet; when the shape memory alloy sheet is in the second memory position, the free end is located inside the cavity, and the second bending portion is located between the first terminal and the shape memory alloy sheet.

[0006] Furthermore, the outer casing has two first inserts protruding outward at one end facing the first terminal, the first opening is located between the two first inserts, the first terminal has a first groove recessed inward corresponding to the position of each first insert, the first groove is adapted to the shape of the first insert, and a second groove is recessed inward between the two first grooves. When the shape memory alloy sheet is in the first memory position, the free end extends out of the first opening and is inserted into the second groove to contact the first terminal.

[0007] Furthermore, the outer casing has two second inserts protruding outward at one end facing the second terminal, the second opening is located between the two second inserts, the second terminal has a third groove recessed inward corresponding to the position of each second insert, the third groove is adapted to the shape of the second insert, a fourth groove is recessed inward between the two third grooves, and the fixed end of the shape memory alloy sheet extends out of the second opening and is fixed in the fourth groove to contact the second terminal.

[0008] Furthermore, a fifth groove is recessed between the second insert near the upper surface of the shape memory alloy sheet and the upper surface of the second terminal, and the first bent portion is fixedly connected to one end of the upper surface of the housing and fixed in the fifth groove.

[0009] Furthermore, the two sides sandwiched between the upper and lower surfaces of the housing and exposed outside the first and second terminals are defined as the first side and the second side, respectively. The first side and the second side are provided with observation ports on the side of the first side and the second side that are close to the first terminal. When the shape memory alloy sheet is in the second memory position, the observation ports are used to expose the second bending portion between the first terminal and the shape memory alloy sheet.

[0010] Furthermore, the direction from the first side to the second side is defined as the measurement direction of the width. When the shape memory alloy sheet is in the second memory position, the width of the second bend is greater than the width of the shape memory alloy sheet.

[0011] Furthermore, both the first terminal and the second terminal are copper terminals with nickel-plated outer surfaces.

[0012] Furthermore, the shape memory alloy sheet is a nickel-titanium shape memory alloy sheet.

[0013] Furthermore, the outer shell is a ceramic shell.

[0014] Furthermore, the bending plate is one of silicone rubber bending plate and fluorosilicone rubber bending plate.

[0015] Beneficial effects:

[0016] As can be seen from the above technical solutions, the present invention provides a safety device based on shape memory alloy, which has the following beneficial effects:

[0017] 1. Low-loss conduction: The free end of the shape memory alloy sheet makes contact with the first terminal at the first memory position. Combined with the nickel-plated copper terminal, the contact resistance is reduced, the heat generation is reduced, and the circuit conduction is achieved in a low-loss mode.

[0018] 2. Low cost and high safety: The shape memory alloy sheet retracts into the cavity at the second memory position. The second bent portion of the insulating bending plate inserts between the first terminal and the shape memory alloy sheet, forming a barrier. Geometric constraints and material rigidity achieve the limiting and circuit breaking. Furthermore, because the second bent portion does not actively retract, it continues to block the contact between the shape memory alloy sheet and the first terminal. Even after cooling, the barrier between the first terminal and the shape memory alloy sheet remains intact, ensuring a continuous circuit break. This prevents the circuit from re-conducting in case of a fault, preventing damage to components from repeated disconnection and reconnection, thus improving safety and reducing the replacement costs of other components by protecting them. Moreover, after manual repair, the bending plate can be actively bent to return the shape memory alloy sheet to the first memory position, enabling reuse and further reducing costs.

[0019] 3. Simple structure and small size: The core consists of two terminals, an insulating shell, an insulating bending plate and a shape memory alloy sheet. It has fewer parts and occupies less space, which is conducive to miniaturization and mass production.

[0020] 4. Stable structure: The inserts on the outer shell side and the grooves of the terminals form a slot-type positioning interface, which facilitates the fixing of the connectors to the first and second terminals. This allows the shape memory alloy sheet to change from the first memory position to the second memory position within the cavity, and to return from the second memory position to the first memory position after maintenance without any changes to the other structures.

[0021] 5. Good visualization effect: The observation ports on the first and second sides allow the insertion of the second bend of the bending plate to be exposed when the device is disconnected, making it easy for maintenance personnel to confirm whether the device is in the power-off retention state without tools.

[0022] 6. Environmental durability: The ceramic shell has high temperature resistance, arc resistance and insulation properties; the silicone rubber or fluorosilicone rubber bending plate has high temperature resistance, insulation and resilience, and the expansion and contraction of the shape memory alloy sheet improves cycle stability.

[0023] 7. High adaptability: The overall structure is roughly composed of a first terminal and a second terminal with a connecting piece, similar to the structure of related fuse devices on the market. It can be adapted to the original circuit. Due to its small size, it can be adapted to high-precision electronic components and has a wide range of applications.

[0024] It should be understood that all combinations of the foregoing concepts and the additional concepts described in more detail below can be considered part of the inventive subject matter of this disclosure, provided that such concepts do not contradict each other.

[0025] The foregoing and other aspects, embodiments, and features of the teachings of the present invention will be more fully understood from the following description in conjunction with the accompanying drawings. Other additional aspects of the invention, such as features and / or beneficial effects of exemplary embodiments, will become apparent from the following description or may be learned through practice of specific embodiments according to the teachings of the present invention. Attached Figure Description

[0026] The accompanying drawings are not drawn to scale. In the drawings, each identical or nearly identical component shown in the various figures may be denoted by the same reference numeral. For clarity, not every component is labeled in each figure. Embodiments of various aspects of the invention will now be described by way of example and with reference to the accompanying drawings, wherein:

[0027] Figure 1 This is a schematic diagram of a safety device based on shape memory alloy in the circuit-connected state according to an embodiment of this application.

[0028] Figure 2 This is a cross-sectional view of a safety device based on shape memory alloy in the circuit-connected state according to an embodiment of this application.

[0029] Figure 3 This is a schematic diagram of a safety device based on shape memory alloy in the circuit-disconnected state according to an embodiment of this application.

[0030] Figure 4 This is a cross-sectional view of a safety device based on shape memory alloy in the circuit-disconnected state according to an embodiment of this application.

[0031] Explanation of icon numbers:

[0032] 1. First terminal; 2. Second terminal; 3. Housing; 4. Shape memory alloy sheet; 5. Bending plate. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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 some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention without creative effort are within the scope of protection of the present invention. Unless otherwise defined, the technical or scientific terms used herein should have the ordinary meaning understood by those skilled in the art to which this invention pertains.

[0034] The terms "first," "second," and similar words used in the specification and claims of this patent application do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, unless the context clearly indicates otherwise, the singular forms of "an," "a," or "the," etc., do not indicate a quantity limitation, but rather indicate the presence of at least one. Terms such as "comprising" or "including" indicate that the element or object preceding "comprising" encompasses the features, integrals, steps, operations, elements, and / or components listed following "comprising" or "including," and do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or sets thereof. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; these relative positional relationships may change accordingly when the absolute position of the described object changes.

[0035] Existing circuit protection components, such as one-time fuses, resettable thermal protectors, and bimetallic circuit breakers, involve trade-offs in terms of size, resettlement capability, conduction loss, post-trigger state retention, and structural complexity: one-time fuses have low conduction loss but are not resettable; resettable thermal protectors have relatively complex structures, high contact resistance, and often require temperature maintenance or external force to maintain the open circuit after disconnection; some electronic protection schemes require continuous power supply, resulting in standby losses and additional costs.

[0036] Therefore, embodiments of the present invention provide a safety device based on shape memory alloy, referring to... Figure 1 and Figure 3 It includes a first terminal 1, a second terminal 2, and a connector fixed between the first terminal 1 and the second terminal 2. The connector includes an insulating housing 3 and an insulating bent plate 5. The housing 3 has a cavity, and the two ends of the cavity facing the first terminal 1 and the second terminal 2 are respectively provided with a first opening and a second opening.

[0037] Reference Figure 1The bending plate 5 includes a first bending part and a second bending part. A slot adapted to the shape of the second bending part is provided on the upper surface of the housing 3 near the first terminal 1. One end of the first bending part is fixedly connected to the upper surface of the housing 3, and the other end of the first bending part is connected to the second bending part so that the second bending part extends into the slot.

[0038] Reference Figure 2 and Figure 4 A shape memory alloy sheet 4 is arranged inside the cavity. One end of the shape memory alloy sheet 4 is a fixed end, which extends out of the second opening and is fixedly connected to the second terminal 2. The other end of the shape memory alloy sheet 4 is a free end and has two memory positions. When the shape memory alloy sheet 4 is in the first memory position, the free end extends out of the first opening and contacts the second terminal 2, and the second bent part contacts the upper surface of the shape memory alloy sheet 4. When the shape memory alloy sheet 4 is in the second memory position, the free end is located inside the cavity, and the second bent part is located between the first terminal 1 and the shape memory alloy sheet 4.

[0039] An insulating shell 3 is provided between the two terminals, forming a cavity; an insulating bent plate 5 is provided on the shell 3, the first bent part of the bent plate 5 is fixed to the upper surface of the shell 3, and the second bent part extends into the slot on the upper surface; the fixed end of the shape memory alloy sheet 4 is electrically connected to the second terminal 2, and the free end has two memory positions: in the first memory position, the free end extends out of the first opening and contacts the first terminal 1, and when placed in the circuit for normal conduction, the first terminal 1 and the second terminal 2 are electrically connected with low resistance; in the second memory position, the free end retracts into the cavity, and the second bent part is located between the first terminal 1 and the shape memory alloy sheet 4. When an overcurrent protection resistor suddenly rises and cuts off the current, the insulating bent plate 5 achieves physical isolation and geometric locking, achieving passive power-off, and realizing the electrical connection between the first terminal 1 and the second terminal 2 is disconnected.

[0040] In some instances, refer to Figure 2 and Figure 4 The outer casing 3 has two first inserts protruding outward at one end facing the first terminal 1. The first opening is located between the two first inserts. The first terminal 1 has a first groove recessed inward corresponding to the position of each first insert. The first groove is adapted to the shape of the first insert. A second groove is recessed inward between the two first grooves. When the shape memory alloy sheet 4 is in the first memory position, the free end extends out of the first opening and is inserted into the second groove to contact the first terminal 1.

[0041] By designing the connection between the first terminal 1 and the housing 3, the contact method and contact area of ​​the free end of the shape memory alloy sheet 4 are restricted, shortening the current-carrying path, reducing contact resistance, and improving repeatability and vibration resistance. The second groove adapts to the shape of the shape memory alloy sheet 4 so that when the shape memory alloy sheet 4 contacts the first terminal 1, the outer surface of the shape memory alloy sheet 4 in contact with the first terminal 1 is completely fitted with the groove surface of the second groove. The first insert extends into the fourth groove and can be fixed by spot welding or riveting.

[0042] In some instances, refer to Figure 2 and Figure 4 The outer casing 3 has two second inserts protruding from one end facing the second terminal 2. The second opening is located between the two second inserts. The second terminal 2 has a third groove recessed inward corresponding to the position of each second insert. The third groove is adapted to the shape of the second insert. A fourth groove is recessed inward between the two third grooves. The fixed end of the shape memory alloy sheet 4 extends out of the second opening and is fixed in the fourth groove to contact the second terminal 2.

[0043] By designing the connection method between the second terminal 2 and the outer shell 3, the fixed end of the shape memory alloy sheet 4 is stably fixed on the second terminal 2, ensuring a stable connection and guaranteeing circuit continuity. The second insert extends into the third groove, and the fixed end extends into the fourth groove, which can be fixed by spot welding or riveting.

[0044] In some instances, refer to Figure 2 and Figure 4 A fifth groove is recessed between the second insert near the upper surface of the shape memory alloy sheet 4 and the upper surface of the second terminal 2. The first bent part is fixedly connected to the upper surface of the outer shell 3 and fixed in the fifth groove at one end.

[0045] A fifth groove is formed between the second insert near the upper surface of the shape memory alloy sheet 4 and the upper surface of the second terminal 2. This groove is used to accommodate and position one end of the first bent portion, achieving rigid positioning of the bent plate 5 and improving the guiding accuracy and anti-skewness capability of the second bent portion during insertion or removal. The first bent portion can be fixed by spot welding or riveting, or by bonding with an insulating adhesive.

[0046] In some instances, see Figure 1 and... Figure 3 The two sides sandwiched between the upper and lower surfaces of the housing 3 and exposed outside the first terminal 1 and the second terminal 2 are defined as the first side and the second side. The first side and the second side are provided with observation ports on the side of the first terminal 1. When the shape memory alloy sheet 4 is in the second memory position, the observation ports are used to expose the second bend between the first terminal 1 and the shape memory alloy sheet 4.

[0047] By opening an observation port, maintenance personnel can accurately and quickly identify whether a circuit break has been completed without tools when performing maintenance, thus improving safety.

[0048] In some instances, the direction from the first side to the second side is defined as the measurement direction of the width. When the shape memory alloy sheet 4 is in the second memory position, the width of the second bend is greater than the width of the shape memory alloy sheet 4.

[0049] The width direction is defined as from the first side to the second side, and the width of the second bend is greater than the width of the shape memory alloy sheet 4. This ensures that the shape memory alloy sheet 4 is fully covered and isolated in the disconnected state, reducing the risk of arc crossing and mis-reset.

[0050] In some cases, both the first terminal 1 and the second terminal 2 are copper terminals with nickel-plated outer surfaces. Using nickel-plated copper terminals for the first terminal 1 and the second terminal 2 balances conductivity, corrosion resistance, and compatibility with crimping processes, while reducing contact resistance and aging rate.

[0051] In some cases, the shape memory alloy sheet 4 is a nickel-titanium shape memory alloy sheet. The nickel-titanium shape memory alloy sheet possesses stable reversible phase transitions and programmable shape memory. The drive stroke and restoring force can be designed according to temperature ranges, enabling the nickel-titanium shape memory alloy sheet to meet the requirements of the first and second memory positions. By using a nickel-titanium shape memory alloy sheet, compared to traditional fuses, the service life is improved, it can stably maintain a completely de-energized state, and its resistance is lower than that of traditional fuses when conducting, which is beneficial to the stable operation of the circuit.

[0052] In some cases, the outer casing 3 is a ceramic casing. In addition to ceramic casing, other insulating materials that meet the requirements of heat resistance, insulation and arc resistance can also be used for the outer casing 3 to achieve reliable protection in a small volume.

[0053] In some cases, the bending plate 5 is either a silicone rubber bending plate or a fluorosilicone rubber bending plate. The bending plate 5 is made of a material that is elastic, non-conductive, non-flammable, and does not easily melt at high temperatures. It provides electrical insulation to achieve a safety function, and its inherent flexibility, combined with the slot guide, provides insertion and buffer protection.

[0054] In the embodiment of this application, a safety device based on shape memory alloy is provided. When the circuit is in normal power-on state, the current passing through it is normal. The current flows in through the first terminal 1, then through the contact between the first terminal 1 and the shape memory alloy sheet 4, then through the fixing point between the shape memory alloy sheet 4 and the second terminal 2, and finally into the subsequent circuit. When the current in the circuit suddenly increases to the point that it exceeds the current limit of the shape memory alloy sheet 4, the shape memory alloy sheet 4 begins to undergo a phase change. The shape memory alloy sheet 4 shortens rapidly and quickly detaches from the first terminal 1, causing the second bent part of the bending plate 5 to penetrate into the slot and block the connection between the first terminal 1 and the shape memory alloy sheet 4, thus breaking the circuit. At this time, the entire subsequent stage receives no current, thus protecting other undamaged circuits and components. At the same time, since there is no large current in the circuit after the shape memory alloy sheet 4 is de-energized, the shape memory alloy sheet 4 will self-recover. However, the circuit is not yet fully repaired and there will still be a large current. Therefore, the second bent part of the bending plate 5 always blocks the connection between the first terminal 1 and the shape memory alloy sheet 4 to maintain the open circuit state, making it easier for subsequent maintenance personnel to carry out repairs while protecting the circuit components and their own safety.

[0055] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Those skilled in the art can make various modifications and refinements without departing from the spirit and scope of the invention. Therefore, the scope of protection of the present invention shall be determined by the claims.

Claims

1. A safety device based on shape memory alloy, characterized in that, It includes a first terminal, a second terminal, and a connector fixed between the first terminal and the second terminal; The connector includes an insulating outer shell and an insulating bent plate. The outer shell has a cavity, and the cavity has a first opening and a second opening at its two ends facing the first terminal and the second terminal, respectively. The bending plate includes a first bending part and a second bending part. A slot adapted to the shape of the second bending part is provided on the upper surface of the housing near the first terminal. One end of the first bending part is fixedly connected to the upper surface of the housing, and the other end of the first bending part is connected to the second bending part so that the second bending part extends into the slot. A shape memory alloy sheet is arranged inside the cavity. One end of the shape memory alloy sheet is a fixed end, which extends out of the second opening and is fixedly connected to the second terminal. The other end of the shape memory alloy sheet is a free end with two memory positions. When the shape memory alloy sheet is in the first memory position, the free end extends out of the first opening and contacts the second terminal, and the second bent portion contacts the upper surface of the shape memory alloy sheet. When the shape memory alloy sheet is in the second memory position, the free end is located inside the cavity, and the second bent portion is located between the first terminal and the shape memory alloy sheet.

2. The safety device based on shape memory alloy according to claim 1, characterized in that, The outer casing has two first inserts protruding outward at one end facing the first terminal. The first opening is located between the two first inserts. The first terminal has a first groove recessed inward corresponding to the position of each first insert. The first groove is adapted to the shape of the first insert. A second groove is recessed inward between the two first grooves. When the shape memory alloy sheet is in the first memory position, the free end extends out of the first opening and is inserted into the second groove to contact the first terminal.

3. A safety device based on shape memory alloy according to claim 2, characterized in that, The outer casing has two second inserts protruding outward at one end facing the second terminal. The second opening is located between the two second inserts. The second terminal has a third groove recessed inward corresponding to the position of each second insert. The third groove is adapted to the shape of the second insert. A fourth groove is recessed inward between the two third grooves. The fixed end of the shape memory alloy sheet extends out of the second opening and is fixed in the fourth groove to contact the second terminal.

4. A safety device based on shape memory alloy according to claim 3, characterized in that, A fifth groove is recessed between the second insert near the upper surface of the shape memory alloy sheet and the upper surface of the second terminal, and the first bent portion is fixedly connected to one end of the upper surface of the outer shell and fixed in the fifth groove.

5. A safety device based on shape memory alloy according to claim 1, characterized in that, Two sides, namely the first side and the second side, are defined as sandwiched between the upper and lower surfaces of the housing and exposed outside the first and second terminals. Both the first side and the second side are provided with observation ports on the side near the first terminal. When the shape memory alloy sheet is in the second memory position, the observation ports are used to expose the second bend between the first terminal and the shape memory alloy sheet.

6. A safety device based on shape memory alloy according to claim 5, characterized in that, The direction from the first side to the second side is defined as the measurement direction of the width. When the shape memory alloy sheet is in the second memory position, the width of the second bend is greater than the width of the shape memory alloy sheet.

7. A safety device based on shape memory alloy according to claim 1, characterized in that, Both the first terminal and the second terminal are copper terminals with nickel-plated outer surfaces.

8. A safety device based on shape memory alloy according to claim 1, characterized in that, The shape memory alloy sheet is a nickel-titanium shape memory alloy sheet.

9. A safety device based on shape memory alloy according to claim 1, characterized in that, The outer shell is a ceramic shell.

10. A safety device based on shape memory alloy according to claim 1, characterized in that, The bending plate is one of silicone rubber bending plate or fluorosilicone rubber bending plate.

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