High-current dual-control delay miniature thermal protector
By using a parallel circuit design of conductive plate, heating wire and PTC thermistor, combined with the action mechanism of bimetallic strip, the problem of high current thermal protector failing to disconnect the circuit in time is solved, realizing effective protection of electrical appliances and persistent disconnection in fault conditions, thus improving the safety and reliability of the circuit.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- YANGZHOU BAOZHU ELECTRIC APPLIANCE CO LTD
- Filing Date
- 2025-04-09
- Publication Date
- 2026-06-02
AI Technical Summary
Existing high-current thermal protectors cannot disconnect the circuit in time when the electrical load current increases abnormally, leading to damage to the electrical appliances, and they are prone to reclosing before the fault is repaired.
The circuit design employs a parallel connection of a conductive plate, a heating wire, and a PTC thermistor, combined with the action mechanism of a bimetallic strip, to ensure rapid circuit disconnection when the current abnormally increases, and to maintain the disconnected state through the PTC thermistor to prevent automatic reset.
This technology enables timely circuit disconnection when current abnormally increases, protecting electrical appliances and preventing damage. It also prevents the thermal protector from closing again before the fault is repaired, thus improving the safety and reliability of the circuit.
Smart Images
Figure CN224318442U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of thermal protectors, specifically a high-current dual-control delay miniature thermal protector. Background Technology
[0002] Thermal protectors are commonly used protective components, and their performance directly affects the safety of the circuit. When thermal protectors are used for high current (such as current greater than or equal to 5A), the bimetallic strip and pins themselves have a large current-carrying capacity. Therefore, when designing thermal protectors, the bimetallic strip can only disconnect at a relatively high temperature. As a result, when the electrical load current in the circuit increases abnormally during use, the thermal protector cannot disconnect the circuit in time, which can easily cause damage to the electrical appliances. Summary of the Invention
[0003] To address the problems existing in the prior art, this utility model provides a high-current dual-control delay miniature thermal protector to solve the aforementioned technical problems.
[0004] To achieve the aforementioned objectives, this utility model provides the following technical solution:
[0005] A high-current dual-controlled delayed miniature thermal protector includes an insulating base, an insulating cover, a first pin, a second pin, and a bimetallic strip. A moving contact is provided on the bimetallic strip. The insulating cover is fixed to the insulating base and encloses it. The first pin and the second pin are embedded within the insulating base. The insulating base is characterized by having a conductive plate, a heating wire, and a PTC thermistor mounted on it. The conductive plate has a stationary contact that mates with the moving contact. One end of the heating wire is electrically connected to the conductive plate, and the other end is electrically connected to the second pin. One end of the PTC thermistor is electrically connected to the first pin, and the other end is electrically connected to the conductive plate.
[0006] Preferably, the insulating base is provided with a first hole, a second hole, and a third hole. The second hole is located in the middle of the insulating base, and the heating wire is fixed in the second hole. The first hole is located at the end of the second hole near the first pin, and the PTC thermistor is located in the first hole. The third hole is located at the end of the second hole away from the first pin. The conductive plate is arranged corresponding to the third hole, so that the stationary contact protrudes out of the third hole. A conductive sheet is provided inside the insulating cover, with one end of the conductive sheet abutting against the conductive plate and the other end abutting against the PTC thermistor.
[0007] Preferably, one end of the conductive sheet is provided with a first conductive protrusion, and the other end is provided with a second conductive protrusion. The first conductive protrusion abuts against the conductive plate, and the second conductive protrusion abuts against the PTC thermistor. The side of the conductive sheet facing away from the conductive protrusion abuts against the insulating cover. One end of the first pin, which is electrically connected to the PTC thermistor, extends to the side of the PTC thermistor facing away from the conductive sheet, and the PTC thermistor abuts against the first pin.
[0008] Preferably, the insulating base has a receiving groove on the side facing away from the conductive sheet for accommodating the bimetallic sheet, and the bimetallic sheet is fixed in the receiving groove.
[0009] Preferably, a pressure block is provided in the receiving groove at the position corresponding to the PTC thermistor, with one end of the pressure block abutting against the bimetallic sheet and the other end abutting against the insulating cover.
[0010] Preferably, the conductive plate is embedded within the insulating base.
[0011] Preferably, the insulating base has an outwardly extending flange at one end near the first pin, and the opening end of the insulating cover contacts the flange.
[0012] Preferably, at room temperature, the resistance of the heating wire is much smaller than that of the PTC thermistor.
[0013] Preferably, at room temperature, the resistance of the PTC thermistor is 100-1000 times that of the heating wire.
[0014] Optionally, the PTC thermistor can be replaced with an NTC thermistor.
[0015] The high-current dual-control delay miniature thermal protector provided by this utility model, under normal use, allows current to flow through the first pin, bimetallic strip, moving contact, stationary contact, conductive plate, parallel circuit consisting of heating wire and PTC thermistor, and the second pin. The heating wire maintains the temperature inside the insulating cover. When the load current of the electrical appliance in the circuit increases abnormally, the heating wire generates more heat, rapidly heating up to the above-mentioned temperature, enabling the bimetallic strip to act more quickly. This allows the thermal protector to disconnect the circuit more promptly, effectively protecting the electrical appliance and preventing damage. When the bimetallic strip acts rapidly, causing the moving contact to disengage from the stationary contact, the thermal protector disconnects the circuit. Current then flows through the first pin, PTC thermistor, conductive plate, heating wire, and second pin. The PTC thermistor and heating wire maintain the temperature inside the insulating cover, preventing the bimetallic strip from automatically returning to its original state. Only when the circuit is manually disconnected can the bimetallic strip return to its original state, preventing damage to the electrical appliance caused by the thermal protector closing again without the operator noticing a circuit fault. Attached Figure Description
[0016] Figure 1 A schematic diagram of the overall structure of the high-current dual-control delay miniature thermal protector in the embodiment is shown.
[0017] Figure 2 An exploded view of the high-current dual-control delayed miniature thermal protector in the embodiment is shown;
[0018] Figure 3 A schematic diagram of the structure of the insulating base and its mounting components is shown;
[0019] Figure 4 It shows Figure 3 A schematic diagram of the structure in which the bimetallic strip and the pressure block are removed;
[0020] Figure 5 It shows Figure 3 A schematic diagram of the structure with the insulating base removed;
[0021] Marked in the attached diagram:
[0022] 10, 10-1, 10-2, 10-3, 10-4, 20, 20-1, 30, 40, 50, 50-1, 60, 70, 80, 90, 100, 101, 102, 103. Detailed Implementation
[0023] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.
[0024] For examples, please refer to Figures 1-5The high-current dual-control delay miniature thermal protector in this embodiment includes an insulating base 10, an insulating cover 20, a first pin 30, a second pin 40, and a bimetallic strip 50. A moving contact 50-1 is provided on the bimetallic strip. The insulating cover is fixed to the insulating base and covers it. The first pin and the second pin are embedded within the insulating base. A conductive plate 60, a heating wire 70, and a PTC thermistor 80 are mounted on the insulating base. A stationary contact 90 that cooperates with the moving contact is provided on the conductive plate. One end of the heating wire is electrically connected to the conductive plate, and the other end is electrically connected to the second pin. One end of the PTC thermistor is electrically connected to the first pin, and the other end is electrically connected to the conductive plate.
[0025] In normal operation, the current flows through the first pin, bimetallic strip, moving contact, stationary contact, conductive plate, parallel circuit consisting of heating wire and PTC thermistor, and the second pin of the aforementioned high-current dual-control delay miniature thermal protector. The heating wire maintains the temperature inside the insulating cover. When the load current of the electrical appliance in the circuit increases abnormally, the heating wire generates more heat, rapidly heating up to the aforementioned temperature. This allows the bimetallic strip to act more quickly, enabling the thermal protector to disconnect the circuit more promptly, effectively protecting the electrical appliance and preventing damage. When the bimetallic strip acts rapidly, causing the moving contact to disengage from the stationary contact, the thermal protector disconnects the circuit. The current then flows through the first pin, PTC thermistor, conductive plate, heating wire, and second pin. The PTC thermistor and heating wire maintain the temperature inside the insulating cover, preventing the bimetallic strip from automatically returning to its original state. Only when the circuit is manually disconnected can the bimetallic strip return to its original state, preventing damage to the electrical appliance caused by the thermal protector closing again without the operator noticing a circuit fault.
[0026] In actual manufacturing, at room temperature, the resistance of the heating wire should ideally be much smaller than that of the PTC thermistor. Generally, the resistance of the PTC thermistor can be 100-1000 times, such as 300, 500 or 800 times, of the resistance of the heating wire.
[0027] In one embodiment, the insulating base is provided with a first hole 10-1, a second hole 10-2, and a third hole 10-3. The second hole is located in the middle of the insulating base, and the heating wire is fixed in the second hole. The first hole is located at the end of the second hole closer to the first pin, and the PTC thermistor is located in the first hole. The third hole is located at the end of the second hole away from the first pin. The conductive plate is provided corresponding to the third hole and can generally be embedded in the insulating base so that the stationary contact protrudes out of the third hole. A conductive sheet 100 is provided inside the insulating cover. One end of the conductive sheet abuts against the conductive plate, and the other end abuts against the PTC thermistor. One end of the conductive sheet is provided with a first conductive protrusion 101, and the other end is provided with a second conductive protrusion 102. The first conductive protrusion abuts against the conductive plate, and the second conductive protrusion abuts against the PTC thermistor.
[0028] The conductive sheet, with its side facing away from the conductive protrusion, rests against the insulating cover. One end of the first pin, electrically connected to the PTC thermistor, extends to the side of the PTC thermistor facing away from the conductive sheet, and the PTC thermistor rests against the first pin. The insulating base, with its side facing away from the conductive sheet, has a receiving groove 10-4 for accommodating the bimetallic strip, and the bimetallic strip is fixed within the receiving groove. A pressure block 103 is positioned within the receiving groove corresponding to the PTC thermistor, with one end of the pressure block resting against the bimetallic strip and the other end resting against the insulating cover. This design makes the thermal protector compact and better meets the requirements of miniature thermal protectors.
[0029] In actual production, the end of the insulating base near the first pin may also be provided with an outwardly extending flange 20-1, and the opening end of the insulating cover contacts the flange. During manufacturing, the contact position may also be sealed with glue.
[0030] In summary, the high-current dual-control delay miniature thermal protector of this application has at least the following advantages:
[0031] 1. Dual protection against overcurrent and overvoltage:
[0032] When the electrical load current in the circuit increases abnormally, the bimetallic strip will quickly disconnect; similarly, when the circuit voltage increases abnormally, the voltage applied to both ends of the heating wire will also increase, leading to an increase in the current passing through the heating wire, which will eventually cause the bimetallic strip to quickly disconnect.
[0033] 2. It has the function of delaying the re-closure of the moving and stationary contacts after the bimetallic strip disconnects them:
[0034] After the bimetallic strip disconnects the moving and stationary contacts, the PTC thermistor and heating wire maintain the temperature inside the insulating cover while heating, preventing the bimetallic strip from automatically returning to its original state.
[0035] 3. The structure is compact and better meets the requirements of miniature thermal protectors.
[0036] It should be noted that in the above embodiments, the PTC thermistor can also be replaced by an NTC thermistor. However, compared to an NTC thermistor, a PTC thermistor has a self-limiting temperature function (when the temperature reaches a certain value, the resistance of the PTC thermistor increases, causing the current to decrease, automatically limiting the heating power). After the moving and stationary contacts are disconnected, the current can be maintained at a stable value, preventing the heating wire from overheating and melting. Both PTC and NTC thermistors can use existing structures, such as thermistor ceramic resistors, which are well known to those skilled in the art and will not be elaborated upon here.
[0037] It should be noted that the terms "one embodiment," "embodiment," "exemplary embodiment," "some embodiments," etc., mentioned in the specification indicate that the described embodiment may include a specific feature, structure, or characteristic, but not every embodiment necessarily includes that specific feature, structure, or characteristic. Furthermore, such phrases do not necessarily refer to the same embodiment. Moreover, when a specific feature, structure, or characteristic is described in connection with an embodiment, implementing such a feature, structure, or characteristic in conjunction with other embodiments, whether explicitly described or not, is within the knowledge scope of those skilled in the art.
[0038] It should be readily understood that “on,” “above,” and “on top of” in this disclosure should be interpreted in the broadest manner, such that “on” means not only “directly on something” but also “on something” with an intermediate feature or layer therebetween, and that “above” or “on top of” means not only “on something” but also “on something” without an intermediate feature or layer therebetween (i.e., directly on something).
[0039] Furthermore, for ease of explanation, spatially relative terms such as "below," "below," "under," "above," and "above" may be used to describe the relationship of one element or feature relative to other elements or features as shown in the figures. Spatially relative terms are intended to encompass different orientations of the device in use or operation other than those shown in the figures. The device may have other orientations (rotated 90 degrees or in other orientations), and the spatially relative descriptive terms used herein may be interpreted accordingly.
[0040] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.
[0041] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.
Claims
1. A large-current double-control delay micro-thermal protector, comprising an insulating base (10), an insulating cover (20), a first pin (30), a second pin (40) and a bimetallic strip (50), a movable contact (50-1) is arranged on the bimetallic strip, the insulating cover is fixed on the insulating base to cover the insulating base, and the first pin and the second pin are embedded in the insulating base, characterized in that, The electrically conductive plate (60), the electric heating wire (70) and the PTC thermistor (80) are mounted on the insulating seat, and the static contact (90) is arranged on the electrically conductive plate and matched with the moving contact; One end of the electric heating wire is electrically connected with the electrically conductive plate, and the other end is electrically connected with the second pin; one end of the PTC thermistor is electrically connected with the first pin, and the other end is electrically connected with the electrically conductive plate.
2. The micro-thermal protector of claim 1, wherein, The first hole (10-1), the second hole (10-2) and the third hole (10-3) are arranged on the insulating seat, the second hole is located in the middle of the insulating seat, and the electric heating wire is fixed in the second hole; The first hole is located at one end of the second hole close to the first pin, and the PTC thermistor is located in the first hole; The third hole is located at one end of the second hole away from the first pin; the electrically conductive plate is arranged corresponding to the third hole, so that the static contact penetrates out of the third hole; The electrically conductive sheet (100) is arranged in the insulating cover, one end of the electrically conductive sheet abuts against the electrically conductive plate, and the other end abuts against the PTC thermistor.
3. The micro-thermal protector of claim 2, wherein the first and second resistors are connected in series to each other and to the first and second terminals, respectively. One end of the electrically conductive sheet is provided with a first electrically conductive protrusion (101), and the other end is provided with a second electrically conductive protrusion (102), the first electrically conductive protrusion abuts against the electrically conductive plate, and the second electrically conductive protrusion abuts against the PTC thermistor; The side of the electrically conductive sheet opposite to the electrically conductive protrusion abuts against the insulating cover; The end of the first pin electrically connected with the PTC thermistor extends to the side of the PTC thermistor opposite to the electrically conductive sheet, and the PTC thermistor abuts against the first pin.
4. The micro-thermal protector of claim 3, wherein the first and second resistors are connected in series to each other and to the first and second terminals, respectively. The side of the insulating seat opposite to the electrically conductive sheet is provided with a containing groove (10-4) for containing the bimetallic sheet, and the bimetallic sheet is fixed in the containing groove.
5. The micro-thermal protector of claim 4, wherein the first and second resistors are connected in series. The containing groove is provided with a pressing block (103) corresponding to the position of the PTC thermistor, one end of the pressing block abuts against the bimetallic sheet, and the other end abuts against the insulating cover.
6. The micro-thermal protector of claim 2, wherein the first and second resistors are connected in series. The electrically conductive plate is embedded in the insulating seat.
7. The micro-thermal protector of claim 1-5, wherein, The end of the insulating seat close to the first pin is provided with a flange (20-1) extending to the outside, and the opening end of the insulating cover is in contact with the flange.
8. The micro-thermal protector of claim 1-5, wherein, At normal temperature, the resistance value of the electric heating wire is much smaller than the resistance value of the PTC thermistor.
9. The micro-thermal protector of claim 8, wherein the first and second resistors are connected in series to each other and to the first and second terminals, respectively. At normal temperature, the resistance value of the PTC thermistor is 100-1000 times of the resistance value of the electric heating wire.
10. The micro-thermal protector of claim 1, wherein, The PTC thermistor is replaced by an NTC thermistor.