Electrical contactor
By introducing a magnetic latch element into the contactor, the connection force between the movable contact and the fixed contact is enhanced by induced magnetic flux, the problem of disengagement of the movable contact during short circuit failure is solved, and the equipment safety and stability in the case of short circuit is achieved.
Patent Information
- Application Number
- CN202311776192.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-22
- Publication Date
- 2025-06-24
AI Technical Summary
In the case of a short circuit fault, the movable contact in the contactor may disengage from the fixed contact due to the Lorentz force, resulting in arc discharge and equipment damage.
By introducing the first and second magnetic latch elements into the contactor, the induced magnetic flux causes the magnetic latch elements to be magnetized and attracted to each other as current flows through the movable contacts, thereby enhancing the connecting force between the movable contacts and the fixed contacts.
During short circuit failures, the strong magnetic attraction between the magnetic latch elements can offset the Lorentz force, preventing the movable contact from the fixed contact, thereby avoiding arc discharge and equipment damage.
Smart Images
Figure CN120199647A_ABST
Abstract
Description
Technical Field
[0001] The present disclosure generally relates to the field of circuit protection devices, and more particularly, to an electrical contactor adapted to handle short-circuit current. Background Art
[0002] A contactor is an electrically controlled switch for switching electric power in a circuit, such as in an electric vehicle. In a typical configuration, a contactor includes a movable armature surrounded by an electromagnetic coil and a fixed iron core. The armature is attached to a conductive movable contact via a shaft. When the coil is energized, it generates an electromagnetic field around the iron core, attracting the armature, which in turn moves the movable contact into engagement with a pair of fixed contacts. The movable contact provides a conductive path between the fixed contacts and allows current to flow through the contactor (e.g., from an automotive battery to various electrical systems within the vehicle). When the coil is de-energized, the armature is allowed to move away from the iron core, which causes the movable contact to move away from the fixed contacts, thus breaking the electrical path between them. Therefore, the flow of current through the contactor is blocked.
[0003] When the coil of the contactor is energized, the generally flat surface of the movable contact moves into engagement with the corresponding generally flat surface of the fixed contact to allow current to flow therebetween. Although the mating surfaces of the movable contact and the fixed contact may appear very flat to the naked eye, they are actually non-uniform and irregular at the microscopic level. Thus, the movable contact and the fixed contact may engage each other only at a plurality of very small points (e.g., at microscopic peaks on the surfaces of the movable contact and the fixed contact). These small contact points act as bottlenecks through which current is transmitted between the surfaces, where the path of the current bends or deviates as the current "funnels" through the bottleneck. This deviation of the path of the current generates a magnetic flux, which generates a force acting on the current (commonly referred to as the Lorentz force), and this force tends to drive the movable contact and the fixed contact away from each other.
[0004] During normal operation of the electrical contactor, the Lorentz force is very weak and is not sufficient to separate the movable contact from the fixed contact. However, during a short-circuit fault condition, an abnormally large current flows through the fixed contact and the movable contact, thereby generating a significant Lorentz force, which may cause the movable contact to move out of engagement with the fixed contact. Since a large amount of current flows through the contactor during a short-circuit fault condition, the separation of the movable contact from the fixed contact generates a violent arc, which may cause catastrophic damage to the contactor and surrounding components.
[0005] One way to address the above problem is to increase the electromagnetic force generated by the coil of the contactor, thereby increasing the force with which the movable contact and the fixed contact remain engaged. However, this method requires a larger coil, thereby increasing the size and cost of the contactor.
[0006] In view of these and other considerations, the present improvement can be useful. SUMMARY OF THE INVENTION
[0007] The present Summary of the Invention is provided to introduce in a concise form selected concepts that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to assist in determining the scope of the claimed subject matter.
[0008] An electrical contactor according to an embodiment of the present disclosure may include a first fixed contact and a second fixed contact arranged in a spaced-apart manner, a movable contact positioned adjacent to the first fixed contact and the second fixed contact, the movable contact being disposed on a first end of a movable shaft that extends through an iron core and is connected to an armature at a second end, an electromagnetic coil around the iron core, a first magnetic latching element disposed on the movable shaft adjacent to the movable contact, and a second magnetic latching element disposed adjacent to the first fixed contact and the second fixed contact, wherein when the electromagnetic coil is energized, the electromagnetic coil generates a magnetic field around the iron core to generate an electromagnetic force that attracts the armature, thereby moving the movable shaft and causing the movable contact to engage with the first fixed contact and the second fixed contact to establish an electrical path therebetween, and wherein when current flows through the movable contact between the first fixed contact and the second fixed contact, the current induces magnetic fluxes in the first magnetic latching element and the second magnetic latching element, whereby the first magnetic latching element and the second magnetic latching element are magnetized and attracted to each other.
[0009] An electrical contactor according to another embodiment of the present disclosure may include an electrically insulating housing that includes a base and a cover removably secured to the top of the base. The electrical contactor may further include a first fixed contact and a second fixed contact disposed within the cover in a spaced-apart arrangement, a first terminal electrically connected to the first fixed contact and a second terminal electrically connected to the second fixed contact, wherein the first terminal and the second terminal extend through respective holes in the cover, a movable contact disposed within the cover and positioned adjacent to the first fixed contact and the second fixed contact, the movable contact being disposed on a first end of a movable shaft that extends through an iron core and is connected at a second end to an armature, wherein the iron core and the armature are disposed within the base, an electromagnetic coil disposed within the base and surrounding the iron core, a first magnetic latching element disposed on the movable shaft adjacent to the movable contact, and a second magnetic latching element disposed within the cover adjacent to the first fixed contact and the second fixed contact, wherein, when the electromagnetic coil is energized, the electromagnetic coil generates a magnetic field around the iron core to generate an electromagnetic force that attracts the armature, thereby moving the movable shaft and causing the movable contact to engage the first fixed contact and the second fixed contact to establish an electrical path therebetween, and wherein, when current flows through the movable contact between the first fixed contact and the second fixed contact, the current induces magnetic flux in the first magnetic latching element and the second magnetic latching element, whereby the first magnetic latching element and the second magnetic latching element are magnetized and attracted to each other. BRIEF DESCRIPTION OF THE DRAWINGS
[0010] Figure 1 is a cross-sectional view showing an electrical contactor in a de-energized state according to an exemplary embodiment of the present disclosure;
[0011] Figure 2 is showing Figure 1 the electrical contactor shown in
[0012] Figure 3 is showing Figure 1 a perspective view of the cover of the electrical contactor shown in
[0013] Figure 4A is showing Figure 1 a detailed perspective view of the movable contact and associated components of the electrical contactor shown in
[0014] Figure 4B is showing Figure 4A a detailed side view of the movable contact and associated components shown in DETAILED DESCRIPTION
[0015] Embodiments of an electrical contactor according to the present disclosure will now be described more fully with reference to the accompanying drawings, in which preferred embodiments of the present disclosure are shown. However, the electrical contactor of the present disclosure may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will convey certain exemplary aspects of the electrical contactor to those skilled in the art. In the drawings, like numbers always refer to like elements unless otherwise indicated.
[0016] Reference Figure 1 , a cross-sectional view of an electrical contactor 10 (hereinafter referred to as "contactor 10") illustrated in accordance with an exemplary embodiment of the present disclosure is shown. For convenience and clarity, terms such as "top", "bottom", "upper", "lower", "above", "below", "vertical", and "horizontal" may be used herein to describe the relative positions and orientations of the various components of contactor 10, all of which are relative to Figure 1 the geometry and orientation of contactor 10 as it appears in
[0017] Contactor 10 generally may include first and second fixed contacts 12a, 12b which are spaced apart from each other and located above a movable contact 14 disposed on a movable shaft 16. The shaft 16 may be configured to move in an axial direction so as to move the movable contact 14 into and out of engagement with the fixed contacts 12a, 12b, as further described below. The fixed contacts 12a, 12b may be adjacent to or electrically connected to respective first and second terminals 18a, 18b which may be used to connect contactor 10 within a circuit (e.g., between a power source and a load). A lower portion of the shaft 16 may extend through a cylindrical ferromagnetic core 20 and may terminate at its lower end in a cylindrical ferromagnetic armature 22. A return spring 24 may be disposed between the core 20 and the armature 22 and may bias the armature 22 downwardly, away from the core 20, as further described below. The return spring 24 may be, for example, a helical spring radially surrounding the shaft 16. An electromagnetic coil 25 may surround the core 20 and the armature 22 and may be connected to a power source (not shown).
[0018] An upper portion of the shaft 16 may include an annular retaining flange 26 projecting radially therefrom. An annular spring support washer 28 may be disposed on top of the retaining flange 26 and a retaining spring 30 may be disposed on top of the spring support washer 28. For example, the retaining spring 30 may be a helical spring radially surrounding the shaft 16. A first magnetic latch element 32 formed of a ferromagnetic material (e.g., low carbon steel) may be disposed on top of the retaining spring 30. As Figure 4A and Figure 4BAs best shown, the first magnetic latch element 32 can be generally U-shaped, having a base plate 34 and opposing side walls 36a, 36b extending vertically from opposing edges of the base plate 34. The shaft 16 can extend vertically through a hole in the base plate 34, and the movable contact 14 can be located on top of the base plate 34 between the side walls 36a, 36b, where the shaft 16 extends vertically through a hole in the movable contact 14. A C-clip 37 can be fastened to the shaft 16 at a location above the movable contact 14 (e.g., clamped into an annular groove 38 in the shaft 16) to prevent the movable contact 14 from being lifted off the shaft 16. The present disclosure is not limited to this aspect.
[0019] Reference Figure 1 , the contactor 10 can further include a housing 40 formed of an electrically insulating material (e.g., plastic or composite material). The housing 40 can include a base 42 that houses the iron core 20, the armature 22, and the coil 25. The housing 40 can further include a cover 44 (also see Figure 3 ), which can be removably secured to the top of the base 42 and houses the first magnetic latch element 32, the movable contact 14, and the first and second fixed contacts 12a, 12b. The cover 44 can be covered by a protective housing 49. The shaft 16 can extend through the top 45 of the base 42 into the base 42 and the cover 44. The first and second terminals 18a, 18b can extend from the first and second fixed contacts 12a, 12b through corresponding holes in the cover 44 and the housing 49. As Figure 3 best shown in, a second magnetic latch element 46 can be disposed within a complementary cavity 48 formed in the top of the cover 44. The second magnetic latch element 46 can be a generally flat plate formed of a ferromagnetic material (e.g., low-carbon steel). For example, the second magnetic latch element 46 can be fixed within the cavity 48 using epoxy resin. The present disclosure is not limited to this aspect.
[0020] In Figure 1 , the contactor 10 is shown in a de-energized state, where the return spring 24 forces the armature 22 downward away from the iron core 20, which in turn pulls the movable contact 14 downward (via the shaft 16) away from the fixed contacts 12a, 12b. Accordingly, there is no electrical path between the fixed contacts 12a, 12b, and no current can flow between them.
[0021] Reference Figure 2, the contactor 10 is shown in the energized state, where current is supplied to the coil 25, for example, through an electronic control unit (ECU) of an automobile (not shown). When the coil 25 is energized in this way, the coil 25 generates a magnetic field around the iron core 20, thereby generating an electromagnetic force that attracts the armature 22. The electromagnetic force is sufficient to pull the armature 22 upward, thereby compressing the return spring 24, which in turn pushes the movable contact 14 upward (via the shaft 16) to engage with the fixed contacts 12a, 12b. Additionally, the holding spring 30 can be compressed between the spring support washer 28 and the first magnetic latch element 32, thereby applying an upward force on the movable contact 14 to keep the movable contact 14 firmly engaged with the fixed contacts 12a, 12b. Thus, the movable contact 14 provides a conductive bridge between the fixed contacts 12a, 12b, allowing current to flow therebetween.
[0022] Additionally, when the contactor 10 is energized as Figure 2 shown, the current flowing through the movable contact 14 can induce magnetic fluxes in the first and second magnetic latch elements 32, 46 (which have moved very close to each other), whereby the first and second magnetic latch elements 32, 46 are magnetized and attracted to each other. The magnetic attraction between the first and second magnetic latch elements 32, 46 can increase as the amount of current flowing through the contactor 10 increases. Thus, in the case of a short-circuit fault condition, where an abnormally large current (e.g., a current in the range of 6 kiloamperes to 8 kiloamperes) may flow through the contactor 10, the magnetic attraction between the first and second magnetic latch elements 32, 46 may be very strong (e.g., in the range of 20 newtons to 25 newtons). In particular, the magnetic attraction between the first and second magnetic latch elements 32, 46 can be stronger than the Lorentz force generated by the current, which would tend to drive the movable contact 14 and the fixed contacts 12a, 12b away from each other. The movable contact 14 thus remains firmly engaged with the fixed contacts 12a, 12b, preventing the catastrophic arc discharge that may occur if the movable contact 14 is driven away from the fixed contacts 12a, 12b (i.e., by the Lorentz force) during a short-circuit fault condition.
[0023] As used herein, an element or step recited in the singular and preceded by the word "a" or "an" should be understood as not excluding a plurality of elements or steps, unless such exclusion is explicitly recited. Additionally, a reference to "one embodiment" of the present disclosure is not to be construed as excluding the existence of additional embodiments that also include the recited features.
[0024] Although the present disclosure refers to certain embodiments, many modifications, variations and changes to the described embodiments may be made without departing from the scope and spirit of the present disclosure as defined in the appended claims. Accordingly, the present disclosure is not limited to the described embodiments, but has the full scope defined by the language of the appended claims and their equivalents.
Claims
1. An electrical contactor, comprising: A first fixed contact and a second fixed contact, which are arranged at intervals; A movable contact, which is positioned adjacent to the first fixed contact and the second fixed contact, the movable contact being provided at a first end of a movable shaft, the movable shaft extending through an iron core and being connected to an armature at a second end; An electromagnetic coil, which surrounds the iron core; A first magnetic latching element, which is provided on the movable shaft adjacent to the movable contact; And A second magnetic latching element, which is provided adjacent to the first fixed contact and the second fixed contact; Wherein, when the electromagnetic coil is energized, the electromagnetic coil generates a magnetic field around the iron core to generate an electromagnetic force that attracts the armature, thereby moving the movable shaft and causing the movable contact to engage with the first fixed contact and the second fixed contact to establish an electrical path therebetween; and Wherein, when current flows through the movable contact between the first fixed contact and the second fixed contact, the current induces magnetic fluxes in the first magnetic latching element and the second magnetic latching element, whereby the first magnetic latching element and the second magnetic latching element are magnetized and attract each other.
2. The electrical contact according to claim 1, wherein The first magnetic latching element is U-shaped, having a bottom plate located below the movable contact and having first and second side walls extending from the bottom plate on opposite sides of the movable contact.
3. The electrical contactor according to claim 1, further comprising a housing formed of an electrically insulating material, the housing including: A base, which houses the iron core, the armature and the electromagnetic coil; And A cover, which is removably fixed to the top of the base, wherein the cover houses the first magnetic latching element, the movable contact, the first fixed contact and the second fixed contact.
4. The electrical contact according to claim 4, further comprising a first terminal electrically connected to the first fixed contact and a second terminal electrically connected to the second fixed contact, wherein, The first terminal and the second terminal extend through corresponding holes in the cover.
5. The electrical contact according to claim 4, wherein, The second magnetic latching element is provided in a cavity in the cover.
6. The electrical contactor according to claim 1, further comprising a return spring located between the iron core and the armature, the return spring biasing the armature away from the iron core.
7. The electrical contact according to claim 6, wherein, The return spring is a helical spring surrounding the movable shaft.
8. The electrical contact according to claim 6, wherein, When the electromagnetic coil is de-energized, the return spring pushes the armature away from the iron core, thereby moving the movable shaft and moving the movable contact out of engagement with the first fixed contact and the second fixed contact.
9. The electrical contactor according to claim 1, further comprising: A retaining flange, which extends radially from the movable shaft; A spring support washer, which is provided on top of the retaining flange; And A retaining spring, which is provided on top of the spring support washer; Wherein, the first magnetic latching element is provided on top of the retaining spring.
10. The electrical contactor according to claim 9, wherein, The retaining spring is a helical spring surrounding the movable shaft.
11. An electrical contactor, comprising: An electrically insulating housing, which includes: A base; and A cover, which is removably fixed to the top of the base; A first fixed contact and a second fixed contact, which are arranged in a spaced-apart manner within the cover; a first terminal electrically connected to the first fixed contact and a second terminal electrically connected to the second fixed contact, wherein the first terminal and the second terminal extend through respective holes in the cover; A movable contact, which is arranged within the cover and is positioned adjacent to the first fixed contact and the second fixed contact, the movable contact being provided at a first end of a movable shaft that extends through an iron core and is connected at a second end to an armature, wherein the iron core and the armature are arranged within the base; An electromagnetic coil, which is arranged within the base and surrounds the iron core; A first magnetic latching element, which is arranged on the movable shaft adjacent to the movable contact; and A second magnetic latching element, which is arranged within the cover adjacent to the first fixed contact and the second fixed contact; wherein when the electromagnetic coil is energized, the electromagnetic coil generates a magnetic field around the iron core to generate an electromagnetic force that attracts the armature, thereby moving the movable shaft and causing the movable contact to engage with the first fixed contact and the second fixed contact to establish an electrical path therebetween; and wherein when current flows through the movable contact between the first fixed contact and the second fixed contact, the current induces magnetic fluxes in the first magnetic latching element and the second magnetic latching element, whereby the first magnetic latching element and the second magnetic latching element are magnetized and attract each other.
12. The electrical contact according to claim 11, wherein, The first magnetic latching element is U-shaped, having a bottom plate located below the movable contact and having first and second side walls extending from the bottom plate on opposite sides of the movable contact.
13. The electrical contact according to claim 11, wherein, The second magnetic latching element is arranged within a cavity formed in the top of the cover.
14. The electrical contactor according to claim 11, further comprising a return spring located between the iron core and the armature, the return spring biasing the armature away from the iron core.
15. The electrical contact according to claim 14, wherein, The return spring is a helical spring surrounding the movable shaft.
16. The electrical contact according to claim 15, wherein, When the electromagnetic coil is de-energized, the return spring pushes the armature away from the iron core, thereby moving the movable shaft and moving the movable contact out of engagement with the first fixed contact and the second fixed contact.
17. The electrical contactor according to claim 11, further comprising: A retaining flange, which extends radially from the movable shaft; A spring support washer, which is arranged on top of the retaining flange; And A retaining spring, which is arranged on top of the spring support washer; wherein the first magnetic latching element is arranged on top of the retaining spring.
18. The electrical contact according to claim 17, wherein, The retaining spring is a helical spring surrounding the movable shaft.