Overcurrent protector
By using a spirally wound flat heating wire and a bimetallic strip structure, the problem of achieving a low cut-off current threshold in a compact space for overcurrent protectors is solved, resulting in higher heat generation and heat transfer efficiency, and ensuring the safe protection of electrical equipment.
Patent Information
- Application Number
- CN202423200754.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-24
- Publication Date
- 2026-02-24
- Estimated Expiration
- 2034-12-24
AI Technical Summary
In the prior art, overcurrent protectors significantly increase in size when achieving low cut-off current thresholds, making it difficult to achieve even lower cut-off current thresholds within a compact space.
It adopts a spiral-wound flat heating wire and a bimetallic strip structure. The heating wire is spirally wound into a flat coil body, increasing its length and bringing it close to the bimetallic strip to improve the heat radiation area and heat transfer efficiency. Combined with the change of contact state between the moving contact and the stationary contact, a low cut-off current threshold is achieved.
While maintaining a compact size, a lower cut-off current threshold is achieved, improving heat generation and heat transfer efficiency and ensuring the safe protection of electrical equipment.
Smart Images
Figure CN223941765U_ABST
Abstract
Description
Technical Field
[0001] This application relates to an overcurrent protector. Background Technology
[0002] Overcurrent protectors are known in practice to cut off the circuit when the current to be protected electrical equipment is too high, preventing damage to the equipment. Overcurrent protectors are widely used in electric vehicles. With the rapid development of electric vehicle technology, some motors used in electric vehicles are becoming smaller and faster. In some applications of motors in electric vehicles, a low cutting current threshold is required for the overcurrent protector, for example, a cutting current threshold below 2A.
[0003] In practice, typical overcurrent protectors are known to have a tripping current threshold of 3-5A, and these protectors typically feature a flat, S-shaped heating wire. To achieve a significantly lower tripping current threshold with such an overcurrent protector, the size of the heating wire would need to be significantly increased, which would correspondingly lead to a significant increase in the overall size of the overcurrent protector. Utility Model Content
[0004] The objective of this application is to provide an overcurrent protector with a compact size.
[0005] The task is solved by an overcurrent protector, which includes a housing and further includes: a bimetallic strip housed in the housing; a moving contact disposed on the bimetallic strip; a stationary contact cooperating with the moving contact; and a heating wire configured to generate heat and radiate heat to the bimetallic strip when current flows through the heating wire; wherein the bimetallic strip actuates when a predetermined temperature threshold is exceeded, causing a change in the contact state between the moving contact and the stationary contact, and the heating wire is spirally wound into a flat coil having at least two turns, with one wide side of the coil facing the bimetallic strip.
[0006] Compared to existing technologies, the overcurrent protector according to this invention achieves a lower interruption current threshold while maintaining a compact overall size. Compared to the planar S-shaped bending heating wire of existing technologies, in this invention, on the one hand, the heating wire can have a significantly increased length, thus generating significantly more heat when energized; on the other hand, the heating wire can be placed closer to the bimetallic strip, and the heat radiation area from the heating wire to the bimetallic strip can also be significantly larger, resulting in significantly higher heat transfer efficiency from the heating wire to the bimetallic strip.
[0007] In some embodiments, the coil body has at least three turns, for example, the coil body has 4 to 20 turns, and optionally 5 to 15 turns.
[0008] In some embodiments, the ratio of the wide side dimension to the narrow side dimension of the coil body is ≥2, for example, 2~10, optionally 2~6 or 2.5~8, for example, 2~4.
[0009] In some embodiments, the wide side of the coil body facing the bimetallic strip extends parallel to the bimetallic strip in the initial state when the bimetallic strip is not in motion.
[0010] In some embodiments, the longitudinal axis of the coil body extends parallel to and / or orthogonal to the length direction of the bimetallic strip in the initial state when the bimetallic strip is not in motion.
[0011] In some embodiments, the coil body extends in a cylindrical surface, the cross-section of which includes two opposing straight sides, particularly parallel straight sides, and two opposing arcuate sides.
[0012] In some embodiments, the straight edge corresponds to the wide side of the coil body, and the arc-shaped edge corresponds to the narrow side of the coil body.
[0013] In some embodiments, the straight edge corresponds to the narrow side of the coil body, and the arc-shaped edge corresponds to the wide side of the coil body.
[0014] In some embodiments, the coil body extends in a cylindrical surface with an elliptical cross-section. Preferably, the ratio of the major axis to the minor axis of the ellipse is ≥3.
[0015] In some embodiments, the overcurrent protector is normally closed, with the moving contact in contact with the stationary contact in the initial state when the bimetallic strip is not activated, and the moving contact separating from the stationary contact when the bimetallic strip is activated.
[0016] In some embodiments, the overcurrent protector is normally open, with the moving contact separated from the stationary contact in the initial state when the bimetallic strip is not activated, and the moving contact making contact with the stationary contact when the bimetallic strip is activated.
[0017] In some embodiments, the housing includes a can-like body and a cover that closes the opening of the can-like body.
[0018] In some embodiments, the bimetallic strip is fixed at one end to the inner bottom surface of the can-shaped body, and the bimetallic strip is electrically connected to a first electrical terminal.
[0019] In some embodiments, the heating wire and the stationary contact are disposed on the cover plate, and the heating wire is electrically connected to the second electrical terminal on one side and to the stationary contact on the other side.
[0020] In some embodiments, the can-shaped body and the first electrical terminal are integrally formed from a sheet metal, and the bimetallic strip is welded to the can-shaped body at one end. Preferably, the moving contact is located on the free end of the bimetallic strip.
[0021] In some embodiments, the cover plate includes a first cover plate component and a second cover plate component separate from the first cover plate component, wherein the first cover plate component and the second electrical terminal are integrally formed from a metal sheet, and a stationary contact is disposed on the second cover plate component.
[0022] In some embodiments, the heating wire is connected to the first cover member at a first end and to the second cover member at a second end.
[0023] In some embodiments, an insulating element is provided between the can body and the cover plate.
[0024] In some embodiments, the heating wire has a circular cross-section, or a square or rectangular cross-section, or a hexagonal cross-section.
[0025] In some embodiments, the overcurrent protector has a cutoff current threshold of less than 2A, for example, 1.2 to 1.8A.
[0026] The technical features mentioned above, those to be mentioned below, and those shown individually in the accompanying drawings can be combined arbitrarily, provided that the combined technical features are not contradictory. All feasible combinations of features are the technical content explicitly described herein. Any one of the multiple sub-features contained in the same statement can be applied independently, without necessarily being applied together with other sub-features. Attached Figure Description
[0027] The present invention will now be described in more detail with reference to the accompanying drawings and exemplary embodiments. A brief description of the drawings is as follows:
[0028] Figure 1 This is a perspective view of an overcurrent protector according to one embodiment of this application.
[0029] Figure 2 yes Figure 1 Another perspective view of the overcurrent protector.
[0030] Figure 3 yes Figure 1 Top view of the cover plate of the overcurrent protector.
[0031] Figure 4 yes Figure 1 A perspective view of the heating wire of an overcurrent protector. Detailed Implementation
[0032] Several exemplary embodiments will now be described more fully with reference to the accompanying drawings. It should be understood that elements not essential for understanding the invention may be omitted from the drawings for ease of illustration and understanding. In the drawings, the same reference numerals may denote the same parts or parts that function identically. Numerous specific details, such as examples of specific parts, devices, and methods, are set forth in the following description to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that not all of these specific details are necessarily required. The exemplary embodiments should not be construed as limiting.
[0033] Figure 1 and Figure 2 A perspective view of an overcurrent protector 10 according to one embodiment of this application is shown from different angles. To allow observation of the structure within the housing 1 of the overcurrent protector 10, the housing 1 is cut along the length X of the overcurrent protector 10. The housing 1 includes a can-shaped body 11 and a cover plate 12 that closes the opening of the can-shaped body 11. The can-shaped body 11 may have a generally cuboid shape. A bimetallic strip 2 is housed within the housing 1. Here, the can-shaped body 11 is integrally formed from a sheet metal and includes a first electrical terminal 7. The bimetallic strip 2 is welded at one end to the inner bottom surface of the can-shaped body 11 and thus electrically connected to the first electrical terminal 7. The bimetallic strip 2 extends along the length X of the overcurrent protector 10. A moving contact 4 is provided at its free end. Figure 3 As shown, the cover plate 12 may include a first cover plate component 13 and a second cover plate component 14 separated from the first cover plate component 13 by a gap. The first cover plate component 13 may be integrally formed from a sheet metal and includes a second electrical terminal 8. The first electrical terminal 7 and the second electrical terminal 8 may extend parallel to each other and be substantially aligned at their free ends. The first electrical terminal 7 and the second electrical terminal 8 are offset in the width direction Y and height direction Z of the overcurrent protector 10.
[0034] The heating wire 3 and the stationary contact 5 can be disposed on the cover plate 12. Specifically, the heating wire 3 can be connected at its first end to the first cover plate component 13, and thus electrically connected to the second electrical terminal 8; the heating wire 3 can be connected at its second end, opposite to the first end, to the second cover plate component 14, and thus electrically connected to the stationary contact 5, which is also disposed on the second cover plate component 14. For good electrical insulation performance, an insulating member 6 can be provided between the can body 11 and the cover plate 12.
[0035] In the current embodiment, the overcurrent protector 10 is normally closed, and in the initial state where the bimetallic strip 2 is not activated, the moving contact 4 is in contact with the stationary contact 5. Conversely, when the bimetallic strip 2 is activated, the moving contact 4 separates from the stationary contact 5.
[0036] In the current embodiment, the heating wire 3 is configured to generate heat and radiate heat to the bimetallic strip 2 when current flows through it. When a current exceeding a predetermined cutoff current threshold flows through the heating wire 3 (e.g., when a motor in an electric vehicle to be protected by the overcurrent protector 10 stalls), the heat generated by the heating wire 3 and received by the bimetallic strip 2 is sufficient to cause the bimetallic strip 2 to actuate when the temperature exceeds a predetermined threshold. Therefore, the moving contact 4 is driven by the bimetallic strip 2 to disengage from the stationary contact 5, and the excessive current flowing through the overcurrent protector 10 is cut off. Consequently, the electrical equipment to be protected (e.g., the motor in an electric vehicle) is protected from damage or even burnout.
[0037] Here, the heating wire 3 is spirally wound into a flat coil body. Generally, the coil body has at least two turns, with one wide side of the coil body facing the bimetallic strip 2. In particular, the coil body has at least three turns, for example, 4 to 20 turns, optionally 5 to 10 turns. In the current embodiment, as... Figure 4 As shown, the coil body has 6 turns. The coil body may have a wide-side dimension a and a narrow-side dimension b, as well as a thickness measured along the longitudinal axis L of the heating wire 3. Advantageously, the ratio of the wide-side dimension a to the narrow-side dimension b is ≥2, for example, 2 to 6, optionally 2 to 4. The thickness of the coil body can depend on the number of turns and the pitch between adjacent turns. In an alternative embodiment, the coil body may have a generally elliptical cross-section, with the major axis of the ellipse corresponding to the wide-side dimension a and the minor axis corresponding to the narrow-side dimension b; advantageously, the ratio of the major axis to the minor axis of the ellipse is ≥3.
[0038] like Figure 1 and Figure 2 As shown, the wide side of the coil body facing the bimetallic strip 2 can extend substantially parallel to the bimetallic strip 2 in its initial state when the bimetallic strip 2 is not activated. More precisely, the wide side of the coil body facing the bimetallic strip 2 can extend substantially parallel to the inner bottom surface of the can-shaped body 11. In the current embodiment, the longitudinal axis L of the coil body extends substantially parallel to the bimetallic strip 2 in its initial state when the bimetallic strip 2 is not activated, and is substantially orthogonal to the length direction of the bimetallic strip 2 (or the length direction X of the overcurrent protector 10). It is also possible that the longitudinal axis L of the coil body and the length direction X of the overcurrent protector 10 can form an angle other than 90°, for example, an angle of 60° to 80°. In the current embodiment, the coil body extends in a cylindrical surface, the cross-section of which includes two opposing, substantially parallel straight edges (wide sides) and two opposing curved edges (narrow sides).
[0039] In a variation, instead of a single coil body, the heating wire 3 may also comprise two coil bodies connected in series. These two coil bodies may be identical or different. These two coil bodies may be arranged sequentially to each other along the length X direction of the overcurrent protector 10.
[0040] In one variant, the overcurrent protector 10 can also be configured as a normally open type, wherein in the initial state when the bimetallic strip 2 is not activated, the moving contact 4 and the stationary contact 5 are separated from each other, and when the bimetallic strip 2 is activated, the moving contact 4 and the stationary contact 5 are in contact with each other.
[0041] In the current embodiment, the turns of the heating wire 3 are identically configured and aligned. In a variation, at least one turn of the heating wire 3 may be configured differently from the other turns, for example, having a different shape and / or different size. In another variation, the turns of the heating wire 3 are identically configured; however, at least one turn of the heating wire 3 may be offset from the other turns, for example, one turn of the heating wire 3 may protrude relative to the other turns.
[0042] It should be noted that the terminology used herein is for illustrative purposes only and is not intended to limit the disclosure. The singular forms “a” and “the one” as used herein should include the plural forms unless the context explicitly states otherwise. It is understood that the terms “comprising” and “including,” and other similar terms, when used in the application documents, specifically describe the presence of the stated operation, element, and / or component, without excluding the presence or addition of one or more other operations, elements, components, and / or combinations thereof. The term “and / or” as used herein includes all arbitrary combinations of one or more of the associated listed items. In the description of the drawings, similar reference numerals always denote similar elements.
[0043] The thickness of the elements in the accompanying drawings may be exaggerated for clarity. It is also understood that if an element is described as being on, coupled to, or connected to another element, then the element may be directly formed on, coupled to, or connected to the other element, or there may be one or more intermediate elements between them. Conversely, if the expressions "directly on," "directly coupled to," and "directly connected to" are used herein, it indicates that there is no intermediate element. Other terms used to describe relationships between elements should be interpreted similarly, such as "between" and "directly between," "attached" and "directly attached," "adjacent" and "directly adjacent," etc.
[0044] Terms such as “top,” “bottom,” “above,” “below,” “over,” “under,” etc., are used to describe the relationship of one element, layer, or region relative to another element, layer, or region, as shown in the accompanying drawings. It is understood that these terms should also encompass other orientations of the device in addition to those described in the accompanying drawings.
[0045] It is understood that although the terms "first," "second," etc., may be used herein to describe different elements, these elements should not be limited by these terms. These terms are merely used to distinguish one element from another. Therefore, a first element may be referred to as a second element without departing from the teachings of this inventive concept.
[0046] It can also be considered that all the exemplary embodiments disclosed herein can be arbitrarily combined with each other. Finally, it should be noted that the above embodiments are only used to understand the present invention and do not constitute a limitation on the protection scope of the present invention. For those skilled in the art, modifications can be made based on the above embodiments, and these modifications do not depart from the protection scope of the present invention.
Claims
1. An overcurrent protector, comprising a housing (1), characterized in that, The overcurrent protector further includes: a bimetallic strip (2) housed in a housing; a moving contact (4) disposed on the bimetallic strip; a stationary contact (5) cooperating with the moving contact; and a heating wire (3) configured to generate heat and radiate heat to the bimetallic strip when current flows through the heating wire; wherein the bimetallic strip actuates when a predetermined temperature threshold is exceeded, causing a change in the contact state between the moving contact and the stationary contact, and the heating wire (3) is spirally wound into a flat coil body, the coil body having at least two turns, and one wide side of the coil body facing the bimetallic strip (2).
2. The overcurrent protector according to claim 1, characterized in that, The coil body has at least three turns.
3. The overcurrent protector according to claim 2, characterized in that, The coil body has 4 to 20 turns.
4. The overcurrent protector according to any one of claims 1 to 3, characterized in that, The ratio of the wide side dimension (a) to the narrow side dimension (b) of the coil body is ≥2.
5. The overcurrent protector according to claim 4, characterized in that, The ratio of the wide side dimension (a) to the narrow side dimension (b) of the coil body is 2 to 6.
6. The overcurrent protector according to any one of claims 1 to 3, characterized in that, The wide side of the coil body facing the bimetallic strip (2) extends parallel to the bimetallic strip in the initial state when the bimetallic strip is not in motion.
7. The overcurrent protector according to any one of claims 1 to 3, characterized in that, The longitudinal axis (L) of the coil body extends parallel to the bimetallic strip and / or orthogonal to the length direction of the bimetallic strip in the initial state when the bimetallic strip (2) is not in motion.
8. The overcurrent protector according to any one of claims 1 to 3, characterized in that, The coil body extends in a cylindrical surface, the cross-section of which includes two opposing parallel straight sides and two opposing arcuate sides, the straight sides corresponding to the wide side of the coil body and the arcuate sides corresponding to the narrow side of the coil body.
9. The overcurrent protector according to any one of claims 1 to 3, characterized in that, The overcurrent protector is normally closed. In the initial state when the bimetallic strip (2) is not activated, the moving contact (4) is in contact with the stationary contact (5), and when the bimetallic strip is activated, the moving contact separates from the stationary contact.
10. The overcurrent protector according to any one of claims 1 to 3, characterized in that, The housing (1) includes a can-shaped body (11) and a cover plate (12) that closes the opening of the can-shaped body. The bimetallic strip (2) is fixed at one end to the inner bottom surface of the can-shaped body. The bimetallic strip is electrically connected to the first electrical terminal (7). The heating wire (3) and the stationary contact (5) are disposed on the cover plate. The heating wire is electrically connected to the second electrical terminal (8) on one side and to the stationary contact on the other side.
11. The overcurrent protector according to claim 10, characterized in that, The can-shaped body (11) and the first electrical terminal (7) are integrally made of metal sheet, and the bimetallic strip (2) is welded to the can-shaped body at one end, with the moving contact (4) disposed on the free end of the bimetallic strip.
12. The overcurrent protector according to claim 10, characterized in that, The cover plate includes a first cover plate component (13) and a second cover plate component (14) separate from the first cover plate component. The first cover plate component and the second electrical terminal are integrally made of metal sheet. The heating wire (3) is connected to the first cover plate component at the first end and to the second cover plate component at the second end. The stationary contact (5) is provided on the second cover plate component. An insulating element (6) is provided between the can body (11) and the cover plate (12).